A 592652
DUPL
S
ts
RY

ARTES
1837
SCIENTIA
VERITAS
LIBRARY
OF THE
UNIVERSITY OF MICHIGAN
E PLUR
RIBUS.
ТГЕВОР
51.
· QUÆRIS-PENINSULAM-AMŒNAM `
CIRCUMSPICE
THE GIFT OF
Mrs. Henry B. Parsons
ELEMENTS
OF
3:27
MODERN CHEMISTRY.
BY ADOLPHE WURTZ,
MEMBER OF THE INSTITUTE, HONORARY DEAN AND
PROFESSOR OF
CHEMISTRY OF THE FACULTY OF MEDICINE OF PARIS, MEMBER
OF THE ACADEMY OF MEDICINE, ETC.
TRANSLATED AND EDITED, WITH THE APPROBATION OF THE AUTHOR,
FROM THE FOURTH FRENCH EDITION,
BY WM. H. GREENE, M.D.,
FORMERLY DEMONSTRATOR OF CHEMISTRY IN JEFFERSON MEDICAL
COLLEGE, PHILADELPHIA, MEMBER OF THE AMERICAN
PHILOSOPHICAL SOCIETY, OF THE CHEMICAL
SOCIETIES OF PARIS AND BERLIN, ETC.
WITH ONE HUNDRED AND THIRTY-TWO ILLUSTRATIONS.
PHILADELPHIA:
J. B. LIPPINCOTT & CO.
LONDON: 16 SOUTHAMPTON ST., COVENT GARDEN.
1879.
Copyright, 1879, by J. B. LIPPINCOTT & Co.
.
PREFACE TO THE AMERICAN EDITION.
THIS book is translated from the fourth French edition by
my pupil and friend, M. Greene, whose perfect familiarity with
the French language and thorough competence, at the same
time, in chemistry I have had occasion to appreciate. The
translation is, then, a faithful, or even improved, representation
of the original work, in which he will certainly have detected
and corrected some faults.
The French editions succeed each other rapidly, showing
that this little book responds to an educational need.
It has been the endeavor to keep it up with the current of
the latest discoveries, and in it to condense a considerable
number of exact and well-selected facts, without banishing the
theory which binds them together. Thus, the origin and foun-
dation of the atomic theory have been given, as far as possible,
in historical order. The notions concerning atomicity, so im-
portant for the appreciation of the structure of combinations
and for the interpretation of chemical reactions, are presented
in an elementary form.
The reader will remark that the history of the metalloids
is relatively more developed than the remainder of the book.
Indeed, this is the fundamental part of chemistry, and a fa-
miliar knowledge of it is indispensable to the fruitful study of
the metals and of organic chemistry. It is also the most at-
tractive portion for beginners, for it is the most easily under-
stood.
Immediately on entering the immense domain of organic
3
4
PREFACE TO THE AMERICAN EDITION.
chemistry, we find the facts overwhelmingly numerous and
complicated. Among all these facts a severe and careful
choice has been made, the historical importance and the theo-
retical and practical interest of the compounds described being
borne in mind. In this respect many additions have been
made to the third French edition. Thus, the question of
isomerism, upon which the theory of atomicity has thrown so
much light, has been treated in a more thorough manner.
The chapter on the aromatic compounds has been considerably
augmented.
The author hopes that these "Elementary Lessons" will be
well received by the new public to whom they are presented,
and that they will contribute to render attractive and diffuse
the knowledge of the science to which he has devoted his life.
ADOLPHE WURTZ.
PARIS, November 20, 1878.
TRANSLATOR'S PREFACE.
It is a privilege to be able to bring before the English-read-
ing public a work by one who has justly won the reputation of
being the most able thinker and perspicuous teacher of France.
M. Wurtz is the acknowledged leader of modern chemical
philosophy, and his labors have firmly established many of
the views which long remained unaccepted by the majority
of chemists, but which are now regarded as essential to the
science.
This book is therefore a brief but accurate embodiment of
modern chemical ideas, arranged in such a form that the most
difficult principles are acquired gradually in the course of the
descriptions.
Only such changes and additions have been made as would
necessarily accompany the change of scene in which the book
appears; among these are the few American mineral waters
mentioned, and other mineral resources of the United States,
naturally interesting and important to the American public.
WM. H. GREENE.
1*
ст
5
ELEMENTS OF MODERN CHEMISTRY.
INTRODUCTION.
THE material objects surrounding us present striking and
infinite differences. Sulphur is readily distinguished from
charcoal, rock-crystal from flint, iron from copper, water from
spirit of wine, and wood from ivory. It is known to all that
these bodies differ not only in form, density, and structure, but
also in their proper substance. They differ, too, in the changes
through which they pass under the same conditions. When
subjected to the action of heat they receive very differently the
impression of that force. They become heated more or less
quickly, and transmit the heat with greater or less rapidity
throughout their own substance. A short bar of iron cannot
be grasped in the hand by one extremity if the other be heated
to redness; under the same conditions a cylinder of charcoal
may be handled with impunity. Communicate sufficient heat to
water and it is converted into steam; remove heat from it, and
if the cooling be sufficient, it is frozen into ice. Spirit of wine
cannot be congealed by the most intense cold known. If a
magnet be placed among iron filings they attach themselves in
tufts around the two poles; on the contrary, copper filings are
indifferent to the magnetic attraction.
Rock-crystal is transparent to light; flint is opaque. These
two bodies are unalterable by fire. They may be heated to red-
ness in a furnace, but after the temperature has abated they
will be found with their original characters unchanged. It is
very different with the coal which we burn in our grates. This
body disappears during the combustion, and leaves only a quan-
tity of ashes. But it has not been destroyed, and its substance
is found in entirety in a certain gas produced by the combus-
tion. Like charcoal, sulphur is combustible, and is converted
by burning into a gas, the suffocating odor of which is well
known.
Neither sulphur nor charcoal undergo any alteration when
7
8
ELEMENTS OF MODERN CHEMISTRY.
exposed to damp air; it is not the same with iron. In a moist
atmosphere this metal experiences a striking and lasting change.
Its surface becomes covered with rust and is no longer iron.
In the forests, the leaves which fall and remain upon the
moist soil are slowly consumed and disappear in the course of
seasons.
All of these changes, these phenomena, take place daily be-
fore our eyes, and are familiar to all of us. On comparison,
striking differences are discovered between them: some are but
passing, and do not affect the proper nature of the body. They
are the results of forces which act at sensible distances, and
which leave the body in its primitive state as soon as their
action has ceased. A piece of soft iron is attracted by the
magnet before contact is established, and when under the mag-
netic influence, is capable of attracting other soft iron in its
turn: the action of the magnet has made the iron itself mag-
netic, but it immediately loses this property when the magnet
is withdrawn; and further, this momentary change in property
has brought about no alteration in the intimate nature of the
iron. It is found after the experiment in precisely the same
condition as before.
In the same manner, rock-crystal undergoes no change in its
specific identity by the passage of a ray of light. Withdraw
from the vapor of water the heat which has been communi-
cated to it, and the liquid water is recovered with all its prop-
erties. Restore to the ice the heat which was abstracted in its
formation, and water is regenerated as before. This is charac-
teristic of the changes produced by physical forces. Under
the influence of such forces, bodies experience modifications.
more or less profound, more or less lasting, but which never
affect their specific nature.
But the iron which rusts undergoes a complete and lasting
change in its properties and in its substance. The rust is no
longer iron, and vainly would it be sought to isolate the metal
by mechanical means, or to discover its presence by the aid of
the most powerful microscopes. The metal has disappeared as
such; it has undergone a complete transformation; it has be-
come another body. It has attracted one of the elements of
the air, oxygen, and has, moreover, fixed to itself the moisture
of the atmosphere. These latter bodies, which differ from iron
in substance, have intimately united with the metal itself, and
the result of this union, of this combination as it is called, is
INTRODUCTION.
9
a new body, rust or hydrated oxide of iron. In this case the
alteration is profound, the change is lasting; the specific nature
of the body is affected. This is characteristic of chemical
action.
In the same manner, when the charcoal and the sulphur are
burned in the air, they attract oxygen and combine with it,
forming two new bodies that are called carbonic and sul-
phurous acids.
These phenomena may be rendered more clear by simple and
well-known experiments.
Experiment 1.-A globe (Fig. 1) is filled with oxygen, a
gas which constitutes one of the elements of the atmosphere,
and which is eminently fitted to support combustion; into it is
plunged a morsel of charcoal lighted at one end; immediately
the coal glows with a brilliant light, the combination takes place
actively, and the charcoal is rapidly consumed. But presently
the light becomes paler, the combustion ceases, and the char-
coal is extinguished. The oxygen is now nearly or quite con-


FIG. 1.
FIG. 2.
sumed, and the globe is filled with another gas which is no
longer oxygen, although it contains that oxygen. It contains
also the matter of the charcoal which has disappeared, and
these two bodies have combined to form a new body, which is
carbonic acid. This latter will not support combustion, and
further, it extinguishes burning bodies. It is then a body
having entirely new properties, and is formed by a chemical
action.
Experiment 2.-Into another jar filled with oxygen (Fig. 2)
is plunged a spoon containing ignited sulphur. The combus-
A*
10
ELEMENTS OF MODERN CHEMISTRY.
tion takes place with a beautiful blue flame, and in burning in
the oxygen with so much energy, the sulphur unites with the
gas and forms with it a new body, which is called anhydrous
sulphurous acid. It is a suffocating gas, which extinguishes
flame. It reddens, and afterwards bleaches, a solution of blue
litmus poured into the jar. These are special properties which
do not belong to the oxygen at first contained in the jar. They
characterize a new body, the result of the combination of the
sulphur with the oxygen, and formed by chemical action.
Carbon, sulphur, and oxygen are simple bodies or elements.
They are so called because from neither of them can more than
one kind of matter be obtained. But when the charcoal in
burning unites with the oxygen, the carbonic acid which re-
sults from the union contains two kinds of matter,--carbon and
oxygen; and these two elements are united in such an intimate
manner that the body which contains both does not resemble
either carbon or oxygen: it is endowed with new properties
which do not in any manner recall those of the elements which
constitute it. In fact, it is a new substance, a compound body
formed by the combination of the matter of the charcoal with
the matter of the oxygen.
Considering the preceding facts, we may give to chemistry
the following definition: chemistry studies those intimate ac-
tions of bodies upon each other which modify their natures
and cause a complete and lasting change in their properties.
Iron may be reduced to a fine powder. This may be mixed
with sulphur itself reduced to powder, and if the mixture be
sufficiently intimate, it will present neither the lemon-yellow
color of sulphur nor the gray-black of finely-divided iron.
Nevertheless, a homogeneous substance cannot be formed in
this manner. If the powder be examined under the micro-
scope, the particles of iron may be recognized disseminated
among those of the sulphur, but not confounded with them.
By the aid of a magnet the iron may be separated. On the
other hand, if the mass be thrown into water, the particles of
iron will sink first to the bottom, while the lighter particles of
sulphur remain in suspension. Thus, after having triturated
the sulphur and iron together, not only can each substance be
recognized in the mass, but they can be again separated by
mechanical means. Here there has been no chemical action,
but simply a mixture. If, however, this mixture be heated,
the sulphur will first be seen to melt, and afterwards the
INTRODUCTION.
11
whole mass will blacken and enter into fusion if the tempera-
ture be sufficiently elevated. After cooling, it is perfectly ho-
mogeneous, and neither iron nor sulphur can be recognized.
Both have disappeared as such, and in their place is found a
substance having new properties; it is the sulphide of iron.
They have disappeared, but their substance is not lost; and
it may be proved by experiment that the weight of the sul-
phide of iron produced is exactly equal to the sum of the
weights of the iron and the sulphur. The ponderable matter
of the iron is then added to the ponderable matter of the sul-
phur, and has formed with it a union so intimate that there
results a new body, the smallest particles of which are per-
fectly similar to each other and to the entire mass.
ample and a thousand others that might be given prove that
when bodies combine there is neither loss nor creation of mat-
ter. The result of the combination, that is, the compound
body, contains the whole of the substance and nothing more
than the substance of the combining bodies. This is an essen-
tial characteristic of chemical combination.
This ex-
The force which presides over chemical combination is called
affinity. It is important that this force be distinguished from
another which is often opposed to it, and which is cohesion.
In order to reduce to powder a solid substance, such as
pyrites or sulphide of iron, it is necessary to overcome the
resistance opposed by the particles of the mass to their separa-
tion. This resistance is due to a special force, which brings
and maintains in relation to each other the homogeneous par-
ticles of the sulphide of iron, as indeed of all solid bodies.
This is cohesion. The particles which are bound together by
this force are not only those minute particles which are visible
to the naked eye or under the microscope, and of which the
most impalpable powder of a solid body is composed. Such
particles still present a magnitude that can be measured; they
must be considered as little masses, so to speak, indivisible by
the mechanical means at our command, but formed in reality
of particles still smaller. These smallest particles of a solid
body which are bound by cohesion are called molecules. They
are not in immediate contact with each other. In a perfectly
compact and homogeneous mass, such as sulphide of iron, the
molecules do not touch each other. Between them exist
spaces of considerable magnitude, compared to the real volume
of the molecule. This idea must not be confounded with po-
12
ELEMENTS OF MODERN CHEMISTRY.
rosity, which is caused by those accidental spaces which form
visible pores in solid bodies. These intermolecular spaces are
those which separate the molecules of a homogeneous and com-
pact solid body, and physicists have further been led to believe
that even in solid bodies the molecules are not perfectly immo-
bile, but that they execute vibratory movements in the spaces
which separate them, at the same time maintaining their own
relative positions.
If a solid body be heated, a part of the heat is employed in
raising the temperature, another part serves to increase the
distances which separate the molecules: the body expands in
becoming heated. But, as the distances between the molecules
increase by the action of the heat and the effect of the expan-
sion, the molecular attraction necessarily becomes more feeble.
Cohesion is thus somewhat diminished, and if the heat be
further increased, it may be so much diminished that the mole-
cules, which have thus far been maintained in definite rela-
tions, can move and glide freely over each other; the solid
body then enters into fusion: it becomes a liquid. The liquid
state is produced by a diminution of cohesion, and is charac-
terized by a greater mobility of the molecules.
But if the liquid body be still further heated, at a certain
point the additional heat may produce such a separation of the
molecules that, already freed from all mutual attraction, they
become completely independent of each other. This is char-
acteristic of the gaseous state.
It may be stated, then, that cohesion is considerable in solid
bodies, but slightly energetic in liquids, and null in gases, and
we have just seen that heat, by causing the changes of state of
a body, can overcome and even practically abolish this physical
force.
Chemical force or affinity is at the same time more intimate
and more powerful. It modifies the molecules themselves. It
brings heterogeneous substances into intimate relations, and
thus produces new molecules. A consideration of the examples
already cited may indicate more clearly the meaning of this
important proposition.
We have brought together sulphur and iron, and by their
reciprocal action and the aid of heat there has been formed a
new body.—sulphide of iron. We know that the smallest mass
of sulphur we can obtain is composed of a collection of per-
fectly homogeneous molecules, aggregated by cohesion. In each
INTRODUCTION.
13
of them but one kind of matter can be found. It is the same
with iron the particles of this metal are perfectly homoge-
neous. Sulphur and iron are simple bodies or elements.
:
Let us now consider the sulphide of iron which results from
their combination. This body also is formed of a collection of
molecules, bound together by cohesion and perfectly similar to
each other, but not homogeneous, for in each molecule we dis-
tinguish two kinds of matter,-sulphur and iron.
It cannot be admitted that these two substances are con-
founded in the molecule, or that the effect of the combination
of sulphur with iron is an interpenetration of the two bodies.
so intimate that they both disappear in what might be called a
homogeneous mixture. On the contrary, it is supposed that
the combination results from the juxtaposition of two infinitely
small masses, each of which possesses a real magnitude and a
constant weight.
These little masses that no force, chemical or physical, can
divide further, constitute the atoms. In each molecule of sul-
phide of iron there exist two of these masses,-one of sulphur
and one of iron; and the atom of sulphur and the atom of
iron are bound together, but not confounded, by chemical force.
And when sulphur combines with iron it is because the atoms
of the sulphur arrange themselves in juxtaposition with those
of the iron, and it is affinity which brings about the action.
When these atoms again separate, the sulphide of iron is said
to decompose. When it attracts the atoms of another body, it
is said to combine with that body.
If sulphide of iron remain for some time exposed to moist
air, its surface becomes covered with an efflorescence formed of
a saline matter. In this case it has attracted one of the ele-
ments of the air, oxygen, with which it has combined to form
green vitriol or sulphate of iron.
The molecules of oxygen, upon which cohesion has no hold,
the body being gaseous, are each formed of two atoms, but
these atoms are of the same kind; the molecules of sulphide
of iron, on the contrary, are each formed of two unlike atoms,-
one of sulphur and one of iron. These latter attract four atoms
of oxygen, which constitute two molecules of that gas, and
these group themselves around the atom of sulphur and the
atom of iron, forming with them one single molecule, more
complex than the primitive molecule of sulphide of iron, for
it contains in addition four atoms of oxygen.
2
14
ELEMENTS OF MODERN CHEMISTRY.
1 molecule
sulphide of iron.
1 molecule 1 molecule
oxygen.
and there results
S.
oxygen.
0
fixes
+
0
1 molecule
sulphate of iron.
S:
0
0
O
It is seen from what precedes that the words molecule and
atom are far from being synonyms. The chemical molecule
constitutes a whole of which the atoms form the parts, and
these atoms are held together by affinity. In the preceding
figure, this exchange of affinities between the atoms is indi-
cated by lines of union.
Chemical molecules have been well compared to edifices:
the atoms constitute the materials, and it is readily conceived
that such molecular edifices differ from each other according
to the nature, number, and arrangement of the atoms, that is,
the materials composing them.
An edifice may be enlarged by the addition of new parts: it
may be reduced in size or it may be entirely demolished. In
the same manner a chemical molecule may be increased by the
annexation of new atoms, or diminished by the separation of
some of those which it already contains. In the first case
there is combination, in the second, decomposition.
We may still further consider these phenomena of combina-
tion and decomposition.
Since the combination of two bodies results from the recip-
rocal action of their atoms, and has for effect a change in the
nature of the molecules, it is evident that it can only take
place when these atoms, and consequently the molecules, are
brought into intimate relations; or more precisely, when the
molecules of one of the bodies enter within the sphere of
action of the molecules of the other body. And this sphere
of action is very limited, for the affinity or elective attraction
of the atoms is only exercised at infinitely small distances.
INTRODUCTION.
15
It results that affinity is often retarded by cohesion, which
maintains the relations between the molecules of a solid body.
These two forces are frequently in opposition, and that the
first may attain the supremacy it is necessary that the other
shall yield. To make manifest or to increase the affinity be-
tween two bodies, it is then necessary to diminish their cohe-
sion. On this condition the molecules can enter within the
spheres of their reciprocal attraction, and the atoms of one
body can attract those of the other.
It has been seen from one of the experiments already cited
that in order to combine iron with sulphur it is necessary to
elevate the temperature. Now, the heat, by fusing the sul-
phur, diminishes its cohesion, and, giving its molecules freedom
of motion, puts them into more intimate contact with those of
the iron. Chemical action then commences.
Instead of heating the sulphur and iron to bring about
chemical action, it would be sufficient to moisten the mixture
with water. By the intervention of this liquid the particles
of sulphur and of iron are, as it were, cemented together and
thus brought into more intimate relations. For a stronger
reason can chemical action between two solids be facilitated by
dissolving them both in water and mixing the solutions. Dis-
solved, they themselves assume the liquid state and lose, in
great part, their cohesion. The ancients understood the in-
fluence of the liquid state upon reactions, and stated it with
exaggeration: Corpora non agunt nisi soluta.
Although the liquid state facilitates chemical reactions, it
does not follow that it always determines them. Frequently
liquids and even gases, after being mixed, must be heated
before they will react upon each other.
Experiment. In a glass tube (Fig. 3) two gases, oxygen
and hydrogen, are mixed in the proportion of one volume of
the first to two of the second. Although the mixture is per-
fectly homogeneous and very intimate, and although the cohe-
sion of the gaseous molecules is null, no action takes place.
But as soon as the mixture is heated by approaching a lighted
taper to the mouth of the tube, combination takes place ener-
getically. An explosion occurs and the two gases unite, form-
ing water. In this case the heat has determined combination
by increasing the intensity of the movements which animate
the molecules of each gas, and so bringing the molecules of the
one within the sphere of attraction of those of the other.
16
ELEMENTS OF MODERN CHEMISTRY.
1
The electric spark produces the same effect, and it probably
acts by the heat which it communicates to the mixture.


FIG. 3.
More rarely combination is brought about by the influence
of light.
If a small bottle be filled with a mixture of equal volumes
of hydrogen and chlorine gases, and then thrown into the air
so that it may be struck by the direct rays of the sun, the
combination of the two gases takes place instantly and with
explosion.
Such are some of the conditions which favor or determine
chemical combination. Let us now study the circumstances
which accompany these phenomena.
Experiment. If sulphur be strongly heated in a small glass
flask until it begins to boil, and some copper turnings be then
thrown into the flask, a brilliant incandescence takes place im-
mediately. It is produced by the combination of the two
bodies. Charcoal, sulphur, and phosphorus produce a brilliant
light when they are burned in oxygen. Their combination
with the gas takes place with evolution of luminous heat.
Whenever a combustible body of whatever nature burns in
the air, the heat and light are developed by the combination
of the body with oxygen, one of the elements of the air. In
general, all chemical combinations give rise to the production of
heat, more or less intense; in certain cases it is luminous, but
more often it is obscure; sometimes it is scarcely perceptible.
While heat acts as the determining cause of a great number
INTRODUCTION.
17
of combinations, and while it is the result of such combination,
it may play still another rôle in chemical reactions. In place
of favoring combination, it may act in the opposite manner,
separating atoms which are united by chemical attraction.
Mercury retains indefinitely its brilliant surface when ex-
posed to the air at ordinary temperatures, but at a temperature
near its boiling-point it slowly attracts the oxygen of the air,
and becomes covered with an orange-red powder, which is oxide
of mercury. In this case heat has assisted the formation of a
compound.
If, however, this red powder be heated in a small retort to a
temperature near redness, it is again resolved into mercury,
which appears in drops in the neck of the retort, and into
oxygen which may be collected.
In this case an intense heat breaks up the compound which
is formed at a temperature less elevated; it occasions a decom-
position.
Heat acts thus in a great number of cases. A body is said
to decompose when the elements composing it are separated
from each other.
The electric spark may occasion such separation when it is
passed through compound gases. If a series of electric dis-
charges be passed through ammonia gas, the latter is decom-
posed, that is, resolved into its two elements,-nitrogen and
hydrogen.
In like manner, the current of the voltaic pile decomposes
a great number of chemical compounds, the elements of which
separate and appear, each at its appropriate pole of the bat-
tery. The decomposing action exerted by the galvanic current
upon chemical compounds was discovered about the commence-
ment of the present century by Nicholson and Carlisle. These
physicists were the first to decompose water by the voltaic
current.
Lastly, light may decompose certain bodies, among which
are a great number of the compounds of silver. The art of
photography is founded upon the decomposing action of light
upon certain of these combinations.
There is a certain class of decompositions which it is impor-
tant to consider with attention. They are occasioned by the
intervention of more powerful affinities than those which main-
tain united the elements of a compound body.
If copper be heated in the air, it attracts oxygen and is con-
2*
18
ELEMENTS OF MODERN CHEMISTRY.
verted into a black powder, a compound of oxygen and copper,
which is called oxide of copper. The affinity which unites the
two bodies is considerable; it cannot be overcome by the ae-
tion of heat alone; at any ordinary temperature to which the
oxide so formed may be exposed, the atoms of copper still re-
main intimately associated with those of the oxygen. But if
this oxide be mixed with powdered charcoal and then heated,
a moment arrives when the affinity of the charcoal for the oxy-
gen is superior to that of the copper. The atoms of oxygen
then abandon the copper and combine with the charcoal, thus
forming a new compound, carbonic acid, which is disengaged
in the form of gas. Here there is at the same time decompo-
sition and combination. The molecules of oxide of copper are
decomposed; those of carbonic acid are formed.
Nothing is created in combinations; nothing is lost in de-
compositions. In the preceding experiment only copper re-
mains; the charcoal and oxygen have disappeared, but their
substance is not lost. All of the matter of the charcoal is

FIG. 4.
found combined with all of the matter of the oxygen in the
product of their combination, the carbonic acid, in such a
manner that the weight of the latter added to the weight of
the copper remaining, exactly represents the weight of the
oxide of copper and charcoal.
INTRODUCTION.
19
+
Experiment. Some oxide of mercury, of which we have
seen the decomposition by heat, may be placed in a tube
through which is passed a current of hydrochloric acid gas, a
gas composed of chlorine and hydrogen (Fig. 4). An ener-
getic reaction takes place. The orange-red powder is converted
into a white crystalline substance, and much heat is produced.
At the same time a small quantity of liquid condenses in the
bulb. This is water, and the white powder formed is mercuric
chloride, or corrosive sublimate, a compound of mercury and
chlorine. The hydrochloric acid has converted the mercuric
oxide into mercuric chloride. The mercury, at first combined
with oxygen, is now combined with chlorine. But what has
become of the oxygen? It has combined with the hydrogen
of the hydrochloric acid, forming water.
We have brought
into presence of each other two compound bodies:
Mercuric oxide,
Hydrochloric acid,
and from their reciprocal action two new compounds result:
Mercuric chloride,
Water or oxide of hydrogen.
This reaction has then occasioned an interchange of elements.
The mercury of the mercuric oxide has combined with the
chlorine of the hydrochloric acid, and the oxygen has left the
mercury and combined with the hydrogen, which was aban-
doned by the chlorine. The reaction has been as easy as
energetic, thanks to the intervention of two affinities, for the
affinity of chlorine for mercury has been aided by that of hy-
drogen for oxygen. Two molecules are decomposed, and two
new molecules are formed by an exchange which may be rep-
resented in the following manner :
Mercury
Hydrogen
BEFORE THE REACTION.
Oxygen
Chlorine
Mercuric oxide.
Hydrochloric acid.
DURING THE REACTION.

Mercury Oxygen
Hydrogen Chlorine
AFTER THE REACTION.
Mercury + Chlorine Mercuric chloride.
=
Hydrogen + Oxygen
=
Water.
20
ELEMENTS OF MODERN CHEMISTRY.
Such reactions, characterized by an interchange of elements,
are called double decompositions. They are the more usual
reactions in chemistry.
The examples cited have been demonstrated by experiments
easy to comprehend and to repeat, and are sufficient to give an
idea of chemical phenomena. We have seen how, on the con-
tact of two heterogeneous bodies, this elective attraction, which
is called affinity and which sets in motion the smallest particles
of bodies, comes into play to produce either combination or
decomposition; we have seen how this force modifies the
chemical molecules either by interposing other molecules, or
under the influence of physical forces, such as heat and elec-
tricity. The study of all these phenomena constitutes chem-
istry, the science of molecular changes; a science grand in
purpose and in magnitude, since it penetrates to the very
nature of the bodies surrounding us; a science unlimited in
its applications, since through it we learn to know and control
the powerful forces which are at work in the most intimate
structure of matter.
If we trace the acquired facts to the most obvious and most
certain conclusion, we must admit the diversity of matter.
There exists, indeed, a certain number of bodies, each of which,
when submitted to the various tests resulting from the applica-
tion of physical and chemical forces, furnishes but one and the
same substance, and it is impossible to obtain anything else
than this substance from the body. We maintain, then, until
proved to the contrary, that each of these bodies contains but
a single kind of matter, and they are called simple bodies or
elements. The chemical forces reside, as has been seen, in the
most remote particles, in the atoms of these bodies. In uniting
together, the elements form compound bodies, and it has al-
ready been stated that such combinations result from the juxta-
position of the atoms which attract each other. The idea of
atoms is an hypothesis, but the hypothesis is based upon nu-
merous and important facts, which it weaves together in the
most natural manner. It is more than an hypothesis: it is a
theory. Chemists have universally adopted it, for it has ren-
dered immense service to the science. Let us proceed, then,
to a consideration of the facts upon which it is based.
DEFINITE PROPORTIONS, EQUIVALENTS.
21
DEFINITE PROPORTIONS, EQUIVALENTS.
The proportions by weight according to which bodies combine are invaria-
ble for each combination-These proportions are the equivalents-Ex-
periments demonstrating this fact.
Experiment.-A test-glass (Fig. 5) contains a liquid which
is universally known as sulphuric acid. Although largely di-
luted with water, that is,

mixed with a large quan-
tity of that liquid, it still
manifests its presence by
energetic properties. It
has a very sour and cor-
rosive taste, a quality of
an acid. If a few drops
of blue litmus solution be
added to it the blue color
instantly changes to bright
red. Another glass contains
a solution of caustic potash
or potassium hydrate. This
FIG. 5.
substance possesses a strong, lye-like, alkaline taste, very easy
to distinguish from that of the acid. The color of the blue
litmus is not affected by this liquid, but if a few drops of the
litmus solution, previously reddened by an acid, be added, the
blue color is immediately restored. This caustic substance
has properties which are different from those of acids, and
which are called basic or alkaline properties. Potassium
hydrate is an alkali or powerful base.
If now the alkaline liquid, which has a blue color, be poured
drop by drop into the acid, which is red, and the mixture be
stirred with a glass rod, a moment arrives when the red color
of the acid liquid changes to blue. Exactly at this moment
we have a solution which has no action upon litmus; it will
not redden the blue solution, neither will it restore the blue
color to the red. This may be demonstrated by dipping into
it first a red and then a blue litmus-paper. Furthermore, this
liquid possesses neither the acid taste of the oil of vitriol nor
the alkaline taste of the caustic potash, but its taste is salty.
By their mixture and reciprocal action the sulphuric acid
and the potash have lost the energetic properties which they
22
ELEMENTS OF MODERN CHEMISTRY.
manifested in the free state. They are exactly saturated; they
are neutralized. That is, the liquid which now contains both,
or more properly the product of their reaction, is neither acid
nor alkaline; it is neutral, and its neutrality is manifested both
by its indifference to vegetable colors and by its effects on our
organs of sense. There is no excess, neither of sulphuric acid
nor of potash, but the two bodies have reacted exactly upon
each other and have both disappeared, and from their recipro-
cal action two new bodies result,—a salt called potassium sul-
phate, and water.
Whenever sulphuric acid is thus saturated by potash, there
arrives a moment when the whole of the acid is precisely neu-
tralized by the alkali, and when the two bodies are converted,
without residue of either one or the other, into potassium sul-
phate and water; and it is always easy to recognize the instant
at which this effect is produced by the action of the liquid upon
vegetable colors, such as solution of litmus, or syrup of violets.
The latter is reddened by an acid, changed to green by an
alkali, and assumes its natural violet tint when the neutral
point is reached. Now, it has been found that this last effect
is only produced when the acid and the alkali are mixed in
certain proportions, which remain invariable, whatever may be
the quantities which are mixed. In other words, it has been
found that the quantities of sulphuric acid and potash which
reciprocally neutralize each other and form potassium sulphate,
maintain a constant ratio to each other. It may be easily proved
that when the state of neutrality has been once attained, it is
immediately passed and disturbed by the least excess of either
acid or base that may be added to the liquid. This is made
evident by the immediate change in the color of the liquid to
either red or green.
Thus, in order to form sulphate of potassium with a given
quantity of sulphuric acid, it is necessary to add an invariable
quantity of potash; and if the quantity of sulphuric acid be
increased by a third, or in any proportion whatever, it is neces-
sary to increase by a third, or in the same proportion, the quan-
tity of potash.
Experiments of this kind have been made with other acids.
and other bases, and have introduced into the science the fun-
damental notion that these bodies react upon each other in
definite proportions to form salts, and that consequently the
composition of the latter bodies is perfectly fixed. A given
DEFINITE PROPORTIONS, EQUIVALENTS.
23
quantity of any acid whatever, invariably saturates a fixed
quantity of the same base. This, then, is the first point.
It may be added that similar researches made towards the
close of the last century have led to a not less important result,
namely, the respective quantities of several acids which satu-
rate a given weight of one base are exactly proportional to the
quantities of the same acids which saturate a given weight of
another base. The law which governs the composition of salts
was discovered towards the close of the last century by a Ger-
man chemist, Richter. We cannot now expose it in detail;
such development will be better placed and better understood
in that part of this work which treats of the formation of salts.
For the present it is sufficient to state that the law mentioned
is a consequence of the law of definite proportions, and that
the latter law is universal. It applies not only to the reaction
of acids upon bases, but is true for all chemical combinations.
It may be thus expressed:
The relative weights according to which bodies combine are
invariable for each combination.
There is one feature of the laws which control the composi-
tion by weight of bodies that it is important to comprehend well.
It may be best illustrated by experiment:
100 gr. of mercury are put into the presence of chlorine
gas, a body possessing very powerful affinities. In this man-
ner mercuric chloride or corrosive sublimate is formed, and it
is found that 35.5 gr. of chlorine are necessary to convert 100
gr. of mercury into this compound. These figures—100 and
35.5-express the invariable ratio in which these elements are
combined in corrosive sublimate. Here we have the definite
proportions.
Now let the 135.5 gr. of corrosive sublimate be dissolved in
water, and a plate of copper be placed in the solution; this
metal will displace the mercury, and combining with the 35.5
gr. of chlorine will form with it cupric chloride, which will
remain in solution, coloring the liquid green. The 100 gr. of
mercury are then precipitated, and it will be found that 31.75
gr. of copper have entered the solution and actually combined
with 35.5 gr. of chlorine.
Into this solution of cupric chloride a plate of zinc is now
plunged; all of the copper is precipitated in its turn, and 33
of zinc enter into combination with the 35.5 gr. of chlorine,
forming zinc chloride.
gr.
24
ELEMENTS OF MODERN CIIEMISTRY.
The 35.5 gr. of chlorine have now been combined success-
ively with
100 gr. of mercury,
31.75 gr. of copper,
33 gr. of zinc.
These numbers, which express the respective quantities of
mercury, copper, and zinc which combine with the same quan-
tity of chlorine, may be called the equivalents of these metals.
In fact, these quantities are equivalent to each other in relation
to the same quantity of chlorine, the experiment having shown
us that in order to displace 100 gr. of mercury combined with
35.5 gr. of chlorine it is necessary to employ 31.75 gr. of
copper or 33 gr. of zinc.
To continue, 100 gr. of mercury are combined with oxygen,
and it is found that this quantity of the metal requires 8 gr. of
oxygen to form the red powder called mercuric oxide.
But how much oxygen is necessary to form cupric oxide
with 31.75 gr. of copper? Remarkable as it seems, exactly
8 gr. are required, and 8 gr. are also requisite to form oxide
of zinc with 33 gr. of zinc.
100 gr. of mercury,
31.75 gr. of copper,
33 gr. of zinc,
which are equivalent compared to 35.5 gr. of chlorine, are then
also equivalent in relation to 8 gr. of oxygen.
Chlorine itself may be oxidized, and there exists a gaseous
compound of chlorine and oxygen which contains precisely 8
gr. of oxygen for 35.5 gr. of chlorine.
Thus, there are required
35.5
of chlorine to form chlorides with .
gr.
8 gr. of oxygen to oxidize
and also
•
•
100 gr. of mercury,
31.75 gr. of copper,
33 gr. of zinc,
8 gr. of oxygen to oxidize 35.5 gr. of chlorine.
In general, if
A, B, C,
combine with D,
combines with E,
A, B, C, combine also with E,
and further, D
the letters A, B, C, D, E, representing the weights of the dif
ferent elements which enter into combination, or the propor-
tions according to which the bodies combine among themselves.
MULTIPLE PROPORTIONS.
25
They are expressed by numbers that have been called combin-
ing weights or equivalents; these represent the ratio of weights
or the relative weights. They are indeed relative to a unit
which has served as a term of comparison, and which is the
equivalent of hydrogen. That is, the quantity of hydrogen
which combines with 35.5 of chlorine being 1, the equivalent
quantities of oxygen, zinc, copper, and mercury will be repre-
sented by the numbers 8-33-31.75-100.
These are the facts of experiment. Let 33 gr. of zinc be
treated with hydrochloric acid, the latter is immediately de-
composed; its chlorine combines with the zinc, forming chlo-
ride of zinc, and its hydrogen is disengaged. In this experi-
ment the hydrogen of the hydrochloric acid is simply displaced
by the zinc. Now, 33 gr. of this metal will displace exactly
1 gr. of hydrogen.
It is seen that the numbers which have been given do not
express absolute quantities, but merely the relative weights ac-
cording to which the bodies combine or replace each other in
compounds, these relative weights being compared to that of
hydrogen, which is taken as unity.
Such is the signification of the numbers.
100
31.75 33
35.5
8
1
of
of
of
of
of
of
mercury, copper, zinc, chlorine, oxygen, hydrogen.
which represent
the equivalents.
This being admitted, in order to determine the equivalent
of an element it is sufficient to find the quantity of that ele-
ment which combines either with 1 of hydrogen or with a
quantity of another element which is equivalent to 1 of hydro-
gen, for instance, 8 of oxygen.
The notion of equivalents can be understood from the pre-
ceding considerations; it appears as a consequence of the law
of definite proportions; it comprehends certain facts relative
to the laws of the composition of bodies, but it by no means
represents the full scope of these laws. The following devel-
opments add important features.
MULTIPLE PROPORTIONS.
Two bodies may combine in several proportions. Thus,
with oxygen, carbon forms two compounds, both of which are
gaseous. The less rich in oxygen is carbon monoxide; the
richer is carbon dioxide, or carbonic acid gas.
Dalton was the
B
3
26
ELEMENTS OF MODERN CHEMISTRY.
first to perceive that for the same quantity of carbon, carbonic
acid contains exactly twice as much oxygen as carbon monoxide.
He made analogous observations concerning the composition
of two compounds of carbon and hydrogen, the monocarbide
of hydrogen or marsh gas, and the dicarbide of hydrogen or
olefiant gas.
From these observations he deduced the law of
multiple proportions, which may be thus stated: when two
bodies, simple or compound, unite in several proportions to
form several compounds, the weight of one of these bodies
being considered as constant, the weights of the other vary
according to a simple ratio.
Thus, taking up one of the examples given above, carbon
unites with oxygen in two proportions:
Carbon monoxide contains 16 parts of oxygen to 12 parts
of carbon.
Carbon dioxide contains 32 parts of oxygen to 12 parts of
carbon. The numbers 16 and 32 are in the ratio of 1: 2.
Nitrogen forms five compounds with oxygen; if such quan-
tities of these compounds be taken as contain the same weight
of nitrogen, the weights of the oxygen will be proportional
to the numbers 1, 2, 3, 4, 5.
Nitrogen monoxide contains for 28 parts of nitrogen 16 parts of oxygen.
Nitrogen dioxide
28
Nitrogen trioxide
"
28
((
Nitrogen tetroxide
28
Nitrogen pentoxide
28
32
48
64
80
(C
،،
These numbers, 16, 32, 48, 64, 80, are multiples of the first
by the numbers 1, 2, 3, 4, 5.
Five compounds of manganese and oxygen are known, and
similar relations exist between the quantities of oxygen con-
tained in these compounds.
The first
contains 55 parts of manganese to 16 of oxygen.
The second
The third
55
66
24
55
6
(6
32
The fourth
The fifth
(C
55
48
55
(6
56
The numbers 16, 24, 32, 48, 56 are in the simple propor-
tion 1: 1.5 : 2 : 3 : 3.5.
Such is the law of multiple proportions discovered by
Dalton.
HYPOTHESIS OF ATOMS.
The brilliant researches of Dalton did not terminate with
the acquisition of facts, but sought to account for them by a
GAY-LUSSAC'S LAWS.-ATOMIC THEORY.
27
theoretical conception. Taking up the old idea of Lysippus
and the word of Epicurus, he supposed all ponderable matter
to be composed of indivisible particles which he called atoms.
He gave a precise meaning to the vague and ancient notion by
considering on one hand that the atoms of each kind of matter,
of each element, possess an invariable weight, and on the other
that combination between different kinds of matter results from
the juxtaposition of their atoms. Such is the atomic hypothe-
sis, the substance of which we have already indicated in treat-
ing of chemical phenomena in a general manner. It permits
a simple and rational interpretation of the laws of the compo-
sition of bodies, and establishes between these laws a firm bond
of theory.
Indeed, if the combination of bodies results from the juxta-
position of their atoms, the latter being considered as indivisi-
ble and possessing a constant weight for each element, it is
evident that combination can only take place in definite pro-
portions, for these proportions represent the invariable relations
between the weights of the atoms which are in juxtaposition.
If, on the other hand, one body may combine with another in
several proportions, such combination can only take place by
the juxtaposition of 1, 2, 3, 4, etc., atoms of one body with
one or more atoms of the other. It evidently results that the
weight of the latter body being constant, the weights of the
other in these various combinations must be multiples of cach
other.
An hypothesis which gives such a simple and precise ex-
planation of the facts relative to definite and multiple propor-
tions is surely worthy of attention. It acquires still further
import and becomes elevated to the rank of a theory when to
these facts are added others entirely different from the first,
but not less important.
GAY-LUSSAC'S LAWS.-ATOMIC THEORY.
Gases combine in simple volumetric proportions-Relations which exist
between the volumes of gases and their atomic and molecular weights—
Equal volumes of gases or vapors contain the same number of molecules
The molecular weights are equal to double the densities compared to
hydrogen.
Among these new facts it is convenient to first notice those
which were discovered by Gay-Lussac, from 1805 to 1808.
They relate to the volumes of gases which combine together.
28
ELEMENTS OF MODERN CHEMISTRY.
Experiment.-10 cubic centimetres of hydrogen and 5 cubic
centimetres of oxygen are introduced into a tube (Fig. 6), which
FIG. 6.
is inverted over the mer-
cury-trough. The gaseous
mixture occupies the up-
per portion of the tube,
which is an eudiometer.
Into the upper extremity
of this tube is hermeti-
cally cemented a small
iron wire with a little
ball at each extremity.
Another iron wire passes
through the wall of the
tube at a short distance
from the upper extremity,
in such a manner that the
interior extremity of this
second wire is opposite,
and at a short distance
from the lower ball of the
superior and vertical wire.
A little iron chain is at-
tached to the exterior end
of the horizontal wire, and

dips into the mercury of the trough. Things being thus
arranged, the inferior extremity of the eudiometer is closed
by an iron cap, and the charged plate of an electrophorus is
approached to the upper button. A spark instantly passes be-
tween the two buttons in the eudiometer, and a bright flash is
seen to fill the whole space occupied by the gaseous mixture.
The combination of the two gases has taken place with the
development of luminous heat. Water has been formed, and
is condensed in drops too small to be perceptible. If now the
eudiometer be opened, by removing the cap which closes it
under the mercury, the latter at once rises to the top of the
tube, and fills the whole of the space at first occupied by the
hydrogen and oxygen. These gases have then combined exactly
in the proportion of 10 volumes of the first to 5 of the second,
or more simply, in the proportion of 2 volumes to 1 volume.
If the eudiometer-tube be now surrounded by a wider glass
tube, and the latter be filled with oil heated to 120°, the heat
GAY-LUSSAC'S LAWS.-ATOMIC THEORY.
29
communicated to the eudiometer will be sufficient to convert
into steam the water which was condensed, and it may be
proved, all corrections being made, that the vapor occupies a
volume equal to exactly 10 cubic centimetres; that is, a volume
equal to that of the hydrogen employed.
From the facts thus established we draw the conclusion that
2 volumes of hydrogen exactly combine with 1 volume of
oxygen to form 2 volumes of vapor of water.
There is thus determined a simple ratio not only between
the volumes of hydrogen and oxygen which combine, but
further, between the volume of vapor of water formed and
the sum of the volumes of the composing gases. 3 volumes
of the latter are reduced to exactly 2 by the combination.
Analogous facts have been discovered for other gases, as
shown by the following examples:
2 volumes of nitrogen + 1 volume of oxygen 2 volumes of nitrogen
monoxide.
2 volumes of chlorine + 1 volume of oxygen = 2 volumes of chlorine
monoxidę.
In other cases the combination of two gases determines a
still greater contraction, and the initial volume is reduced one-
half.
Thus
1 volume of nitrogen + 3 volumes of hydrogen 2 volumes of ammonia
gas.
Finally, when two gases combine in equal volumes, their
combination usually takes place without contraction; in other
words, the volume of the gas produced is equal to the sum of
the volumes of the component gases.
From these collected facts we may draw the following general
conclusions:
1. There is a simple relation between the volumes of gases
which combine.
2. There is a simple relation between the sum of the volumes
of the combining gases and the volume of the gas resulting
from the combination.
These laws were first signalized by Gay-Lussac, whose name
is attached to them. Their importance is immense; they have
added a notable development to the atomic theory.
If the definite proportions by weight in which bodies com-
bine represent, according to Dalton, the relative weights of
their atoms, it is natural to conclude that the definite and
simple proportions by volume in which gases combine, accord-
3*
30
ELEMENTS OF MODERN CHEMISTRY.
ing to Gay-Lussac, represent the volumes occupied by the
atoms. Under the same volume gases would then contain
the same number of atoms. This was first proposed by Am-
père, who based his conclusion on the important consideration
that gases dilate and contract nearly equally when submitted
to the same variations of temperature and pressure. Within
certain limits the proposition is true; it applies to a large num-
ber of simple gases. But if equal volumes of these gases,
measured, let it be well understood, under the same conditions
of temperature and pressure, contain the same number of atoms,
it is evident that the weights of these equal volumes should
represent the weights of the atoms. In other words, the
atomic weights of the simple gases should be proportional to
their densities.
•
The densities of gases and vapors represent the weights of
these gases or vapors compared to the weight of an equal
volume of air. To determine the density, a certain volume of
the given gas is weighed, and this weight is divided by that of
an equal volume of air, under the same conditions of tempera-
ture and pressure.
The air is then the unit to which are com-
pared the densities of gaseous bodies. On comparing these
densities to that of hydrogen,' which we take as unity, we find
that the same numbers express almost exactly the densities and
the atomic weights, the unit to which the densities are com-
pared, that is, hydrogen, being the same as that to which are
compared the atomic weights. The figures in the following
table demonstrate this to be the case:

ELEMENTS.
Densities of
Gases or Vapors,
Air being Unity.
Densities,
Hydrogen being
Unity.
Atomic
Weights.
Hydrogen
Oxygen
0.0693
1
1
1.1056
15.9
16
Nitrogen
0.9714
14
14
•
Sulphur (density at 1000°)
2.22
32
32
Chlorine
2.44
35.2
35.5
•
Bromine
5.393
77.8
80
Iodine.
8.716
125.8
127
1 To do this it is sufficient to multiply the densities of the gases compared
1
to air by
= 14.44, which is the density of the air compared to hy-
0.0693
drogen as unity.
GAY-LUSSAC'S LAWS.-ATOMIC THEORY.
31
It is seen from this table that if the densities of gases be
compared to hydrogen as unity, just as the weights of their
atoms are compared to hydrogen as unity, the same figures, or
very nearly the same figures, express both the densities and
the atomic weights. We may add that, for all the elements
taken in the gaseous state, there has been determined between
the densities referred to hydrogen and the atomic weights, if
not equality, at least a simple ratio. These remarkable rela-
tions were pointed out by Gay-Lussac.
Equal volumes of the simple gases above enumerated con-
tain the same number of atoms. Two volumes of hydrogen,
then, contain twice as many atoms as one volume of oxygen;
and when these gases combine in the ratio of 2 volumes of the
first to 1 of the second, we must admit that each atom of oxy-
gen combines with 2 atoms of hydrogen. We say, then, that
water is composed of 2 atoms of hydrogen and 1 atom of oxy-
gen.
These three atoms so united constitute the smallest
quantity of water that can exist in the free state.
called a molecule of water.
This is
But what volume does this molecule occupy? The experi-
ment has shown us. We have seen that 2 volumes of hydro-
gen, in combining with 1 volume of oxygen, yield 2 volumes
of vapor of water. One molecule of water in the gaseous state,
then, occupies 2 volumes, if 1 atom of hydrogen occupy 1
volume, and if 1 atom of oxygen occupy 1 volume. It is
seen that the volumes represent the atoms, and the relative
weights of equal volumes, that is, the densities, represent the
weights of the atoms.
Let us now consider another compound gas,-ammonia,-
composed of hydrogen and nitrogen. A very simple experi-
ment will show in what proportion the atoms of these elements
are combined in this gas, and the volume occupied by the
compound compared with the volumes of its component gases.
Experiment.-100 volumes of ammonia gas are introduced
into a tube inverted upon the mercury-trough (Fig. 7), and
the walls of which are pierced at the upper end by two plati-
num wires, between the ends of which a small space is left.
To these wires are attached the extremities of the two con-
ducting wires of a Ruhmkorff coil, and the current is passed
so that a series of electric sparks traverses the ammonia between
the extremities of the wires in the tube. The gas is imme-
diately decomposed, and the level of the mercury in the tube
32
ELEMENTS OF MODERN CHEMISTRY.
is depressed. When the experiment has terminated it is found
that the volume of the gas has been doubled. Instead of 100
volumes, there are now 200, the gas being measured under the
same conditions of temperature and pressure as before. It is
found, by an analytical process that will be indicated further
on, that these 200 volumes of gas resulting from the decompo-

FIG. 7.
sition of 100 volumes of ammonia are composed of 150 vol-
umes of hydrogen and 50 volumes of nitrogen. These 150
volumes of hydrogen and 50 volumes of nitrogen are condensed
by their union into 100 volumes of ammonia. In other words,
3 volumes of hydrogen and 1 volume of nitrogen are combined
together in 2 volumes of ammonia. And as the volumes rep-
resent atoms, it follows that in ammonia gas 3 atoms of hydro-
gen are combined with 1 atom of nitrogen. But the quantity of
ammonia containing 1 atom of nitrogen and 3 atoms of hydro-
gen is the smallest quantity of ammonia that can exist. It is
a molecule of ammonia, and this molecule occupies 2 volumes,
if 1 atom of nitrogen or 1 atom of hydrogen occupy 1 volume.
Here, then, is another compound gas,-ammonia,—of which
the molecule occupies 2 volumes, like that of water. It is the
same with all the gases. All of the atoms which are combined
to constitute the molecule of a gas or vapor are so condensed
that the molecule occupies the same volume as the molecule of
vapor of water, or the molecule of ammonia.
We may state, then, with the Italian chemist, Avogadro,
that equal volumes of gases contain the same number of mole-
cules, and that each of these molecules occupies 2 volumes,
if 1 atom of hydrogen occupy 1 volume. It follows that
the weight of 2 volumes of a compound gas represents the
weight of its molecule, the weight of one volume of hydrogen
GAY-LUSSAC'S LAWS.-ATOMIC THEORY.
33
being 1. But the weight of 2 volumes of a gas or vapor is
nothing more than the double of its density compared to hy-
drogen; for the density is the weight of 1 volunie compared
with the weight of 1 volume of hydrogen. To find the weight
of the molecule (the weight of 2 volumes) of a gas or vapor,
it is then only necessary to multiply its density compared to
hydrogen (the weight of 1 volume) by 2.
4
1
The densities of gases and vapors are generally referred to
air as unity. To bring them to the hydrogen standard, they
are multiplied by the number expressing the relation of the
density of hydrogen to that of air, which is .09 14.44.
The product thus obtained expresses the density compared to
hydrogen, that is, the weight of 1 volume. To find the weight
of 2 volumes, or the molecular weight, it is then only necessary
to multiply the densities compared to air by twice the ratio of
the density of the air compared to hydrogen, that is, by the
constant factor,—
2 X
1
0.0693
2
0.0693
28.88.
It is seen that if the atomic weights of certain gases can be
deduced from a comparison of their densities, this same physi-
cal notion may also serve for the determination of the molecu-
lar weights of compound gases.
The numbers which represent double the densities of gases
or vapors compared to hydrogen, express also the molecular
weights of these gases or vapors, that is, the weight of all
the atoms in the molecule, the weight of one atom of hydrogen
being 1.
Considering the examples already given, we may deduce the
molecular weights of water and of ammonia from the densities
of steam and ammonia gas.
The density of vapor of water, determined by Gay-Lussac-
is 0.6235. To find the molecular weight of water, it is suffi-
cient to multiply this figure by 28.88. The product, 18, ex-
presses the weight of a molecule of water, which is indeed
composed of
2 atoms of hydrogen
1 atom of oxygen
1 molecule of water
·
2
16
18
Sir Humphry Davy found for the density of ammonia the
B*
34
ELEMENTS OF MODERN CHEMISTRY.
number 0.5901. This being multiplied by 28.88, the product,
17.04, should represent the weight of one molecule of am-
monia. Ammonia contains
3 atoms of hydrogen
1 atom of nitrogen.
1 molecule of ammonia
•
3
•
14
17
The discovery of the laws which govern the combination of
gases by volume has seconded in the most efficacious manner
the progress of the atomic theory.
In the first place, it has established a marked distinction be-
tween the old idea of equivalents and the modern one of atoms.
The equivalents represented merely the ponderable proportions
according to which bodies combine; the atomic weights repre-
sent the relative weights of the volumes of gases which com-
bine. The equivalent of hydrogen-unity-expressed merely
that hydrogen was the unit to which were referred the weights
of other bodies with which it entered into combination. The
atomic weight of hydrogen is the weight of one volume of
hydrogen, taken as unity, and to this unit are referred the
atomic weights of other bodies.
In the second place, the discovery of Gay-Lussac has shown
how the atomic weights of simple bodies and the molecular
weights of compound bodies can be determined from the den-
sities of gases and vapors.
However, this resource would be insufficient in very many
cases. It only applies to gaseous bodies, or such as can be
conveniently converted into vapor. Now, there are many sub-
stances with which this is impossible, and serious difficulties
would be encountered in the determination of the atomic
weights of certain elements were it not for another physical
law, discovered by two French physicists, Dulong and Petit.
It denotes the relations which exist between the specific heats
and the atomic weights.
LAW OF SPECIFIC HEATS.
It is known that in order to raise the temperatures of differ-
ent bodies through the same number of thermometric degrees
very different amounts of heat are required. Thus, one kilo-
gramme of water requires 30 times more heat than one kilo-
gramme of mercury to raise its temperature one degree, and
if the quantity of heat required to raise the temperature of
LAW OF SPECIFIC HEATS.
35
the
one kilogramme of water one degree be represented by 1,
quantity required to raise the same weight of mercury one
degree will be represented by 0.0333. This fraction ex-
presses the specific heat of mercury between 0 and 100°.
The specific heat of a solid or liquid body is then the amount
of heat required to raise the temperature of a certain weight of
the body one degree, the amount required to raise the tempera-
ture of an equal weight of water one degree being taken as
unity.
In 1820, Dulong and Petit discovered the remarkable fact
that if the figures which express the atomic weights of the
elements, liquid or solid, be multiplied by those which express
their specific heats, the product obtained is sensibly constant;
in other words, the specific heats of the elements are inversely
as their atomic weights. It results that if such quantities of
the elements be taken as represent their atomic weights, the
amount of heat required to raise the temperature of each one
degree will be sensibly the same. The law discovered by Du-
long and Petit may then be expressed,-the atoms of the solid
elements possess sensibly the same specific heats.
This law permits the deduction of the atomic weights from
the specific heats. Indeed, it is evident that if the product of
the specific heats by the atomic weights be a constant, that
may be called the atomic heat, dividing this product by the
specific heat should give the atomic weight. The product
which represents the atomic heat is 6.4, very nearly, as may be
seen from the following table:

NAMES OF THE SOLID ELEMENTS.
Specific Atomic
Heats. Weights.
Products of the
Specific Heats
by the Atomic
Weights.
Atomic Heats.
Sulphur, between 0 and 100°
0.2026
32
6.483
Selenium
0.0762
79.5
6.058
Tellurium
0.0474
129
6.115
Bromine, between -78 and ·20°
0.0843
80
6.744
Iodine, between 0 and 100°
0.0541
127
6.873
Phosphorus, between + 1 and 30°
0.1887
31
5.850
Arsenic
0.0814
75
6.105
Carbon, diamond, at 600°
0.46
12
5.52
Boron, crystallized, at 600°

0.5
11
5.5
Silicon, at 1000°
0.202
28
5.66
Potassium
0.1695
39.1
6.500
36
ELEMENTS OF MODERN CHEMISTRY.
TABLE.-Continued.

NAMES OF THE SOLID ELEMENTS.
Specific Atomic
Heats. Weights.
Products of the
Specific Heats
by the Atomic
Weights.
Atomic Heats.
Sodium, between -34 and + 70
0.2934
23
6.748
Lithium
Thallium
•
0.9408
7
6.586
•
0.03355
204
6.844
Magnesium
Aluminium
Manganese
•
0.2499
24
5.998
0.2143
27
5.786
0.1217
55
6.693
Iron
0.0110
56
6.116
Zinc
0.09555
65.2
6.230
Cadmium
•
0.05669
112
6.349
Cobalt.
0.1068
59
6.301
Nickel.
•
0.1089
59
6.424
Tungsten.
0.0334
184
6.146
Molybdenum
0.0722
96
6.931
Lead
0.0314
207
6.499
•
Bismuth
0.0308
210
6.468
Copper
•
0.09515
63.5
6.042
Antimony
0.05077
122
6.193
Tin.
0.05623
118
6.635
Mercury, between -77.5 and -14°
0.03247
200
6.494
Silver
0.05701
108
6.157
•
Gold
0.0324
197
6.383
Platinum
0.03293
197.5
6.503
Palladium
Osmium
0.0593
106.5
6.315
0.03063
199.2
6.101
Rhodium
Iridium
•
•
0.05803 104.4
0.058
0.03259
198
6.452
Carbon, silicon, and boron have long been regarded as ex-
ceptions to Dulong and Petit's law. Their specific heats had
been determined at comparatively low temperatures, and the
products of the numbers obtained by the atomic weights fell
much below 6.4. These exceptions have disappeared; the ex-
periments of M. Weber have shown that the specific heat of
carbon, silicon, and boron increases with the temperature, and
that for the first two elements it attains a limit, where it re-
mains sensibly constant. The figures given in the preceding
table for these three elements are those of M. Weber, and it is
seen that on multiplying them by the respective atomic weights
of carbon, silicon, and boron, values are obtained which are
sensibly near 6.4.
It will otherwise be remarked that there are sensible differ-
ISOMORPHISM.- -CHEMICAL NOMENCLATURE, ETC. 37
ences between the numbers expressing the atomic heats of the
various solid elements, showing that Dulong and Petit's law,
although true in its generality and striking in its enunciation,
is not free from certain perturbations which give to it the
character of an approximate law. It is the same with other
physical laws, Mariotte's law, for example.
ISOMORPHISM.
While considering the atomic theory and the determination
of the relative weights of the ultimate particles of bodies, we
cannot pass in silence a discovery which has had a great influ-
ence upon the development of that theory. It is due to E.
Mitscherlich, who, in 1819, made known the law of isomor-
phism. This law may be thus stated: there is such a relation
between the atomic constitutions of compound bodies belonging
to the same group and their crystalline form, that "the same
number of atoms combined in the same manner produce the
same crystalline form, the latter being independent of the
chemical nature of the atoms, and determined solely by
their number and arrangement." The importance of the
proposition as regards the atomic structure of bodies is self-
evident. We will reconsider it when treating of the general
characteristics of salts, but we may remark here that it has
been of great value in the determination of certain atomic
weights. Indeed, in some cases considerations of a chemical
nature cannot decide between two numbers for the atomic
weight of a given element. The choice is then determined by
the following considerations: such a value must be attributed
to the atomic weight that the isomorphous compounds formed
by the element and by another to which it is analogous, may
be represented by similar atomic formula.
CHEMICAL NOMENCLATURE AND NOTATION.
GENERAL CONSIDERATIONS.-Sixty-four substances are now
known which can be resolved into no simpler forms of matter,
and which are consequently considered as simple bodies or ele-
ments. By combining together, they form an innumerable mul-
titude of compound bodies containing two or more elements.
4
38
ELEMENTS OF MODERN CHEMISTRY.
In order to distinguish these bodies from cach other it is neces-
sary to give a name to each, for each constitutes a distinct sub-
stance.
The names of the simple bodies have been chosen at will,
and in some cases recall some peculiar property of the sub-
stances designated. It was formerly the same with compound
bodies; there was no definite rule for their nomenclature.
From this there resulted a great complication of words which
embarrassed the exposition of ideas, and often for the same sub-
stance there were a number of synonyms, of which the least
inconvenience was to uselessly fatigue the memory.
Hence
chemists have felt the necessity of a regular nomenclature,
applicable to compound bodies, and capable of indicating their
composition. Such is the principle of the chemical nomen-
clature suggested by Guyton de Morveau, and developed by
Lavoisier, Berthollet, and Foureroy. This nomenclature, with
some modifications, introduced by the progress of the science,
is still adopted.
Independently of this language, the rules of which will
presently be detailed, chemists have adopted a written nota-
tion which expresses in concise form the atomic constitution
of compounds. The name of cach element is represented by
a symbol, which also expresses one atom of the substance.
This symbol is the initial letter of the name of the element,
or the initial letter with another when the names of two ele-
ments begin with the same letter. Thus, H represents one
atom of hydrogen weighing 1; O represents one atom of
oxygen weighing 16. By combining these symbols together,
it is easy to represent in a precise manner the atomic compo-
sition of compound bodies. From such combinations result
chemical formulas, the use of which was introduced into the
science by Berzelius.
In the following table will be seen the names of the ele-
ments now known, together with their atomic weights, and the
symbols by which the atoms of the elements are represented in
the notation.
The greater number of the elements possess certain physi-
cal properties which characterize them as metals. They are
opaque, and possess a peculiar lustre, which does not disappear
under the burnisher. They are good conductors of heat and
electricity.
CHEMICAL NOMENCLATURE AND NOTATION.
39


NAMES OF THE ELE-
MENTS.
Symbols.
Atomic
Weights.
NAMES OF THE ELE-
MENTS.
Symbols.
Atomic
Weights.
Aluminium
Al
27.5
Antimony (stibi-
um).
Sb 122
Mercury (hydrar-
gyrum)
Molybdenum
Hg 200
Mo
96
Arsenic
As
75
Nickel
Ni
59
•
Barium
Ba
137
Bismuth
Bi
210
Boron .
Bo
11
Niobium
Nitrogen.
Osmium
Nb
94
N
14
Os
199.2
•
Bromine
Br
80
Oxygen
0
16
Cadmium
Cd
112
Palladium
Pd
106.6
•
Cæsium
Cs
133
Phosphorus.
P
31
Calcium
Ca
40
Platinum
Pt
197.5
•
Carbon
Cerium
Chlorine
Chromium
Cobalt
Copper
Didymium
Erbium
C
12
•
Potassium(kalium)
K
39.1
Ce
92
Rhodium.
Rh
104.4
CI
35.5
Rubidium
Rb
85.2
Cr
52.5
Ruthenium
Ru
104.4
Co
59
Selenium.
Se
79.5
•
Cu
63.5
Silicon
Si
28
•
Di
96
Silver (argentum)
Ag
108
Er
112.6
Sodium (natrium)
Na
23
Fluorine
FI
19
Strontium
Sr
87.5
•
Gallium
•
Ga
69.9
Sulphur
S
32
•
Glucinium
Gl
9.5
Tantalium
Ta
182
Gold (aurum)
Au
197
Tellurium
Te
128
Hydrogen
H
1
Thallium.
TI
204
•
Indium
In
113.4
Thorium.
Th
234
Iodine
I
127
Tin (stannum)
So
118
Iridium
Ir
198
Titanium
Ti
50
•
Iron (ferrum)
Fe
56
Tungsten (wolfra-
Lanthanium
La
92
mium
W
184
Lead (plumbum)
Pb
207
Uranium
Ur
120
Lithium
Li
7
Vanadium
V
51.37
•
•
Magnesium
•
Mg
24
Yttrium
I
89.6
Manganese
Mn
55
Zinc
Zn
65.2
•
Zirconium
Zr
90
erties.
Other elements, fewer in number, do not possess these prop-
They have been called the non-metallic bodies, some-
times the metalloids. They include the following:
HYDROGEN.
OXYGEN.
SULPHUR.
CIILORINE.
SELENIUM.
BROMINE.
TELLURIUM.
IODINE.
NITROGEN.
PHOSPHORUS.
ARSENIC.
ANTIMONY.
(BISMUTH?)
BORON.
SILICON.
CARBON.
FLUORINE.
From a theoretic stand-point this distinction presents but
40
ELEMENTS OF MODERN CHEMISTRY.
little value, for it is impossible to draw an exact line sepa-
rating the metals from the non-metallic bodies.
NOMENCLATURE OF COMPOUND BODIES.-The principle of
chemical nomenclature is to indicate the composition of com-
pound bodies by their names. Among such compounds the
most numerous and the most important are those containing
oxygen. They are binary or ternary; that is, the oxygen in
them is combined with one or two other elements.
Binary Oxygen Compounds.-We will first consider the
more simple oxidized bodies, those which result from the com-
bination of oxygen with but one other element, metallic or
non-metallic. These compounds are called oxides, and differ
as the element associated with the oxygen is metallic or non-
metallic. In combining with non-metallic elements, oxygen
generally forms compounds which are the anhydrides of acids,
that is, compounds capable of uniting with water to form
acids; with the metals it forms metallic oxides.
Experiments.-1. A small piece of phosphorus is placed in
a capsule floating on the surface of mercury. It is ignited
and the capsule covered with a bell-jar (Fig. 8). The phos-
phorus burns, giving off a thick smoke, which condenses in

FIG. 8.
white flakes on the sides of the bell-jar. This substance re-
sults from the combination of the phosphorus with the oxygen
of the air: it is phosphorus pentoxide, or phosphoric anhydride.
CHEMICAL NOMENCLATURE AND NOTATION.
41
2. If lead be heated in the air and maintained for some
time in a state of fusion, its brilliant surface becomes tarnished
and covered with grayish particles, which are finally converted
into a yellow powder. This body is formed by the combina-
tion of the lead with oxygen: it is plumbic oxide, or oxide of
lead.
But, as we have seen, such combination can take place in
different proportions. An atom of a body may unite with
1, 2, 3, or more atoms of oxygen, and the names of the com-
pounds so formed should indicate the degree of oxidation.
Sulphur forms two compounds with oxygen: one contains 2
atoms of oxygen to 1 atom of sulphur; the other, 3 atoms of
oxygen to 1 of sulphur. They are designated by the names
sulphurous oxide, or anhydride, and sulphuric oxide, or anhy-
dride.
The written notation represents them by the symbols
SO2 >
SO³,
which express their atomic compositions. The number of
atoms of any element is indicated by a small figure placed after
and a little above or below the symbol of that element.
The degree of oxidation is then expressed by the termina-
tion in ous or ic of the name of the other element, which
indicates the kind of oxide, ic denoting the superior oxide.
Mercury forms two compounds with oxygen. The first
contains 2 atoms of mercury for 1 of oxygen; the second, 1
atom of mercury to 1 of oxygen. They are designated by the
names and symbols as follows:
Mercurous oxide
Mercuric oxide.
Hg20.
HgO.
The names monoxide, sesquioxide, dioxide, etc., as will be
seen further on, are also employed.¹
A monoxide
A sesquioxide
A divxide
is a combination of 1 atom of metal with 1 atom of oxygen.
2 atoms
1 atom
3 atoms
2 (C
It is easy then to understand the signification of the follow-
ing names and symbols:
1 The prefixes proto, bi or deut, and ter have been, and are yet, frequently
employed instead of mono, di, and tri.
4*
42
ELEMENTS OF MODERN CHEMISTRY.
Manganese monoxide .
Manganese sesquioxide
Manganese dioxide
MnO.
Mu²0³.
MnO2.
The oxide most rich in oxygen is sometimes called the per-
oxide.
Oxygen Acids and Metallic Hydrates.-The oxygen com-
pounds that we have just considered may unite with the ele-
ments of water to form more complex compounds, which are
ternary, that is, they contain three elements. To the two ele-
ments of the oxide is then added a third, independently of the
oxygen of the water, that is, its hydrogen.
The oxygen acids usually result from the union of water
with the non-metallic oxides.
Experiment. Sulphur trioxide or sulphuric anhydride
occurs in white silky tufts. It is very volatile, and if a bottle
containing it be opened, its vapor comes in contact with the
moist air and forms thick white fumes. If a small quantity of
this substance be thrown into water, it immediately disappears
and combines with that liquid. So great is the energy of the
reaction that the heat disengaged gives rise to the production
of steam, which, being suddenly formed and condensed in the
midst of the cooler liquid mass, causes a peculiar noise, a sort of
hissing. When the sulphuric oxide is dissolved in the water,
the solution presents a very acid reaction. It contains sulphuric
acid, the compound long known under the name of oil of vitriol.
This reaction may be represented in the abbreviated lan-
guage of the notation, which expresses the atomic composition
of bodies with so much precision. The formula of sulphuric
anhydride or sulphur trioxide is
that of water is
ᏚᎤ ;
H2O.
Then if sulphuric acid result from the addition of all of the
elements of water to those of sulphuric trioxide, it should contain
SO³ + H2O H2SO¹.
This is a chemical equation, and it is seen that the two
terms of the first member express the atomic composition of
the reacting bodies, while the single term of the second mem-
ber gives the atomic composition of the product of the reac-
tion. Such an equation accounts for all of the atoms, and
CHEMICAL NOMENCLATURE AND NOTATION.
43
the sum of all of the atoms written in the first member must
exactly balance the sum of all those written in the second.
There is a compound known as nitric anhydride, or nitrogen
pentoxide. It results from the combination of nitrogen with
oxygen, and its atomic composition is represented by the
formula N2O5. In combining with water it forms nitric acid.
N2O5 +
Nitric anhydride.
(1 molecule.)
H2O
Water.
2(HNO³).
Nitric acid.
(2 molecules.)
These examples, which could be indefinitely multiplied, give
an idea of the constitution of the ternary oxygen acids. The
rules which have been already given for the nomenclature of
the oxides apply also to the nomenclature of the acids. We
have phosphorous acid and phosphoric acid. Hypo-phosphor-
ous acid is an acid of phosphorus containing still less oxygen
than phosphorous acid. (Hypo, literally, under.)
The metallic hydrates result from the combination of water
with the metallic oxides. It is well known that when quick-
lime is sprinkled with water it becomes heated, increases in
volume, cracks into pieces, and is finally converted into a white,
impalpable powder, which constitutes slaked lime,—a com-
pound of the lime with water. Lime is the oxide of a metal
called calcium. In combining with water it forms a ternary
compound of calcium, hydrogen, and oxygen; this is hydrate
of calcium, or, as it is commonly called, hydrate of lime.
CaO + HẢO
Calcium oxide.
(Lime.)
Water.
CaH2O².
Calcium hydrate.
The metal potassium, the radical of potash, forms with oxy-
gen a compound which contains two atoms of potassium com-
bined with one atom of oxygen. The composition of this body
is then represented by the formula K2O.
It combines with water with great energy, and forms with it
potassium hydrate or caustic potassa.
K2O + H2O
Potassium oxide.
Water.
2KOH.
Potassium hydrate.
(2 molecules.)
Oxygen Salts. The oxygen salts result from the action of
the oxygen acids upon the oxides or upon the metallic hydrates.
Experiment. The formation of a salt may be illustrated by
a modification of one of the experiments already described.
A quantity of dilute nitric acid is slightly reddened by a so-
44
ELEMENTS OF MODERN CHEMISTRY.
1
lution of blue litmus or syrup of violets. Some dilute solution
of caustic potassa is also treated with the same coloring matter;
the syrup of violets will assume a green color, or blue litmus
will remain unchanged.
The latter liquid, which is alkaline, is now added drop by
drop to the acid, until the red color disappears, giving place to
the violet color of the syrup of violets or the blue of the litmus.
The liquid is now neutral. It contains neither free nitric acid
nor free potassa. Both have disappeared as such; they are
reciprocally neutralized, the first having lost its acid taste, the
second its extreme caustic properties. They have produced a
body having a saline, cooling taste, and exerting no action upon
vegetable colors. It is a neutral salt which has been formed.
It is called potassium nitrate. It is the nitre or saltpetre of
the ancient chemists. It is not, however, the sole product of
the reaction. Water is formed at the same time, and if we
would comprehend the entire phenomenon, the reaction will be
expressed by the following equation:
HNO³ + KOH
Nitric acid.
KNO³ + H³O.
Potassium hydrate. Potassium nitrate. Water.
It is seen that the salt, potassium nitrate, is a ternary com-
pound, similar in constitution to nitric acid itself. On com-
paring the two formule,
HNO³ nitric acid,
KNO³ potassium nitrate,
it is seen that they only differ by the K in the second occupy-
ing the place held by the H in the first. It may then be said
that potassium nitrate represents in a manner nitric acid in
which the hydrogen has been replaced by an equivalent quan-
tity of potassium. This definition applies to the entire class
of compounds under consideration. A salt represents an acid
of which the hydrogen has been wholly or partially replaced
by an equivalent quantity of metal.
The acids constitute the salts of hydrogen: they are neu-
tralized when this hydrogen is replaced by a metal. The acid
or hydrogen salt differs from the metallic salt. From a theoretic
point of view, an acid is a compound of the same order as a
salt, and if these bodies are separated by such great differences
1 An infusion of common purple cabbage may be substituted for syrup
of violets.
CHEMICAL NOMENCLATURE AND NOTATION.
45
of properties, this is due to the nature of the base. What
a difference, indeed, between hydrogen gas and the metals!
We have studied the formation of asalt by the action of an acid,
nitric acid, upon a metallic hydrate, potassium hydrate. The
anhydrous oxides may also form salts by reacting with the acids.
Experiment.-Yellow oxide of lead, when digested with
dilute sulphuric acid, is converted into a white, insoluble pow-
der, which is lead sulphate. This is a salt, but it is not the only
product of the reaction, for water is formed at the same time.
H²SO + PbO PbSO¹ + H2O.
Water. -
Sulphuric acid. Lead oxide. Lead sulphate.
Lastly, among other modes of formation of salts, there is one
which is worthy of interest, and of which an idea may be ob-
tained from the following example.
Sulphur trioxide, or sulphuric anhydride, combines energetic-
ally with barium oxide or baryta, and from the union of all of
the elements of both compounds there results a salt,—barium
sulphate.
SO³ +
BaO
Sulphur trioxide. Barium oxide.
BaO,SO³ or BaSO¹.
Barium sulphate.
But, whether this salt be formed under these conditions, or
by the action of sulphuric acid, its composition only differs
from that of the latter acid by the substitution of Ba for H³.
H2SO sulphuric acid, hydrogen sulphate,
BaSO¹ barium sulphate.
The reactions which we have just studied, and which indicate
the principal methods of the formation of salts, are sufficient to
make clear the definition before given, that salts are derived from
acids by the substitution of a metal for hydrogen. The nomen-
clature defines and preserves these relations. To distinguish the
different salts of the same acid, the name of the metal is placed
first, and this is followed by the name of the acid, which is but
slightly changed,-ic is changed to ate, and ous to ite.
Thus Sulphuric acid.
Nitric acid
Perchloric acid
Sulphurous acid
Hyposulphurous acid
gives sulphates.
66
((
nitrates.
perchlorates.
sulphites.
hyposulphites.
These generic names follow the names of the metals which
enter into the composition of the salts, and which specify them,
as it were.
Thus, we have:
46
ELEMENTS OF MODERN CHEMISTRY.
Potassium sulphate, copper sulphate, lead sulphate, etc.;
Sodium sulphite ;
Potassium nitrate, barium nitrate, silver nitrate, etc.
But we know that a single metal may form several com-
pounds with oxygen. In reacting upon the same acid these
different oxides give rise to the formation of different salts.
Thus, two different sulphates of copper are obtained, as sul-
phuric acid is caused to react with cuprous oxide, or with
cupric oxide.
H³SO¹ + Cu2O
Sulphuric acid.
H2SO¹ +
Cuprous oxide.
CuO
Cupric oxide.
Cu2SO4 +
+ H2O.
Cuprous sulphate.
Water.
CuSO + H2O.
Cupric sulphate.
It is easy to distinguish these two salts from each other by
using the adjectives cuprous and cupric before the substantive
sulphate. Thus, we have mercurous and mercuric sulphates;
ferrous and ferric sulphates.
The preceding considerations will give an idea, sufficient for
the time being, of the constitution and the nomenclature of
salts. Their further exposition will be completed farther on.
Nomenclature of Non-Oxygenized Compounds.-The non-
metallic elements other than oxygen can combine among them-
selves or with the metals. Such compounds are designated by
the name of one of the elements followed by the abbreviated
name of the other terminating in ide. Thus, the compounds
of the metals with chlorine, bromine, iodine, sulphur, arsenic,
and carbon are called chlorides, bromides, iodides, sulphides,
arsenides, carbides. We thus have sodium chloride, potassium
bromide, lead iodide, zinc arsenide, iron carbide. The termi-
nation uret was formerly used in place of ide.
But a non-metallic body, such as chlorine or sulphur, can,
like oxygen, form several compounds with the same metal. In
these compounds 1 atom of metal may be united with 1 or 2
atoms of sulphur, or with 1, 3, or 5 atoms of chlorine, or again
with 2 or 4 atoms of chlorine. Such atomic composition is
expressed by the following names and symbols:
Iron monosulphide
Iron disulphide
Phosphorus trichloride
Phosphorus pentachloride
Tin dichloride
Tin tetrachloride
Antimony trichloride
Antimony pentachloride
FeS.
•
FeS2.
PCB.
PC15.
SnCP2.
•
SnCl4.
SbCB.
SbC15.
CHEMICAL NOMENCLATURE AND NOTATION.
47
The names thus express precisely the number of atoms of
the second element in combination with 1 atom of the first.
The compounds of chlorine, bromine, iodine, and several
other elements with hydrogen are acids; they readily exchange
their hydrogen for a metal, so forming compounds that are
analogous to the oxygen salts, and which constitute the haloid
salts of Berzelius.
Experiment. The compound of chlorine with hydrogen is
hydrochloric acid; it is a gas, and dissolves in water, forming
a fuming, strongly-acid liquid. When it is carefully poured
into a concentrated solution of caustic potassa there appears a
white precipitate, formed of little crystals and presenting the
appearance of a salt. This is potassium chloride. It is formed
according to the following reaction, and its formation is at-
tended by the production of heat :
HCI + KOH
Hydrochloric
acid.
Potassium
hydrate.
KCl + H2O.
Potassium
chloride.
Water.
The hydrogen compounds of bromine, iodine, fluorine, sul-
phur, etc., possess analogous properties. They are called
Hydrobromic acid
Hydriodic acid
Hydrofluoric acid
•
•
HBr.
HI.
IIFI.
II'S.
Sulphydric acid or sulphuretted hydrogen .
The chlorides may combine among themselves. It is the
same with the bromides, iodides, sulphides, etc. If a solution
of potassium chloride be poured into a concentrated solution
of platinic chloride, a yellow precipitate, constituting a com-
pound of the two chlorides, is formed. It is the double chlo-
ride of platinum and potassium, or potassium platino-chloride.
There exist, likewise, double sulphides formed by the union
of two simple sulphides. Such compounds constitute what are
called sulphur salts.
Alloys and Amalgams.-The compounds of the metals
with each other are called alloys. Amalgams are the alloys
of mercury, that is, the compounds of this liquid metal with.
another metal.
48
ELEMENTS OF MODERN CHEMISTRY.
HYDROGEN.
Density compared to air
0.0693.
Atomic weight (1 volume taken as unity) II 1.
This body was discovered in 1766 by Cavendish. It is one
of the elements of water, hence its name, which was given by
Lavoisier.
Experiments.-1. A small piece of sodium is passed under a
tube filled with mercury and inverted
on the mercury-trough; it rises to
the top of the jar, and some water
is then introduced (Fig. 9). As soon
as the water touches the sodium a
brisk disengagement of gas is ob-
served; this is hydrogen, produced by
the decomposition of the water, and
the reaction by which it is set at
liberty is expressed in the following
equation:

FIG. 9.
2H2O + Na² = 2NaOH + H².
Sodium Hydrogen.
hydrate.
Water. Sodium.
If the tube be now inverted and a lighted taper be rapidly
brought to the orifice, the gas will burn with a pale flame. A
piece of reddened litmus-paper plunged into the water con-
tained in the tube has its blue color at once restored, and
this change is produced by the sodium hydrate or caustic soda
dissolved in the water.
2. Some thin sheet-zinc cut into small pieces is introduced
into a rather large test-jar (Fig. 10), and some hydrochloric
acid is then poured upon it. A rapid effervescence imme-
diately takes place, and if a lighted taper be brought to the
mouth of the jar, the stream of hydrogen evolved takes fire.
This hydrogen is produced by the decomposition of the hydro-
chloric acid by the zinc, which is converted into chloride.
2HCI + Zn
+
Hydrochloric
acid.
(2 molecules.)
ZnCl2 + H².
Ilydrogen.
Zinc.
Zinc
chloride.
IIYDROGEN.
49
Preparation.-A reaction analogous to the preceding is
turned to advantage for the preparation of large quantities of
hydrogen.
Dilute
sulphuric acid is de-
composed by zinc.

A two-necked bot-
tle is about half filled
with water, and gran-
ulated zinc, or sheet-
zinc cut into small
pieces, is introduced;
sulphuric acid is then
added in small quan-
tities by the aid of
a funnel-tube which
dips under the surface
of the water (Fig.
11). The reaction at
once commences, and
hydrogen is disen-
gaged. When the
air at first contained
in the bottle has been
entirely expelled, the
gas may be collected
in jars or bottles filled
with water and in-
verted on the pneu-
matic trough.
FIG. 10.
In this reaction the zinc disappears and dissolves in the
liquid with evolution of heat, and it often happens, if the liquid
be sufficiently concentrated, that colorless crystals of zinc
sulphate are formed on cooling. This salt and hydrogen are
the sole products of the reaction of pure zinc upon sulphuric
acid largely diluted with water.
H2SO4 + Zn
Sulphuric acid.
Zinc.
ZnSO4 + H².
Zinc sulphate. Hydrogen.
Physical Properties.-Hydrogen is a colorless gas, and
when pure has neither taste nor odor. It is the lightest of all
known bodies, its density compared to air being 0.0693; that
is, if one volume of air weigh 1, one volume of hydrogen,
measured under the same conditions of temperature and pres-
C
5
50
ELEMENTS OF MODERN CHEMISTRY.
sure, weighs only 0.0693. Hydrogen is then 14.44 time
lighter than air. The weight of one litre of hydrogen at 0°

)
nmom\/
Fig. 11.
and under the normal pressure is 0.0895 gramme. Instead
of comparing the densities of gases and vapors to that of air,
it is preferable to compare them to that of hydrogen taken as
unity (page 30).
Hydrogen passes with great facility through vegetable and
animal membranes, and through porous substances that are im-
pervious to water. It cannot be kept in a glass vessel that
presents the least crack, for it would pass through much more
readily than air. This property is expressed by saying that hy-
drogen is very diffusible. According to Magnus, it is the only
gas gifted with an appreciable conductibility for heat; in this
respect it is related to the metals. From a consideration of its
physical properties and its combined chemical properties, Fara-
day long ago announced the metallic character of hydrogen.
This theoretic prediction has recently received a remarkable
confirmation. Hydrogen, which was long regarded as incoerci-
ble, has been liquefied and even solidified. Cailletet, of Paris,
obtained it in the form of a cloud by exposing it to a pressure
of 300 atmospheres at a temperature of -29° and then sud-
denly relieving the pressure. Raoul Pictet, of Geneva, hast
advanced still further. By an apparatus of incomparable.
power, he subjected it to a temperature of 140° under a
pressure of 650 atmospheres. Under these circumstances, hy-
drogen was liquefied, and was visible as a steel-blue, liquid jet
HYDROGEN.
51
at the moment of its projection from the tube in which it was
condensed. The cold produced by its passage from the liquid
to the gaseous state was so great that a portion of the liquid was
solidified, and fell to the ground in metallic grains, producing
a shrill sound as it struck the floor. Another portion of the
solidified hydrogen remained in the tube during several minutes.
Among the physical properties of hydrogen may be men-
tioned the remarkable faculty it possesses of passing through
plates of iron or platinum at high temperatures (H. Sainte-
Claire Deville and Troost). It is well known that it rapidly
passes through thin sheets of caoutchouc. According to
Graham, this property is related to that possessed by certain
solid bodies, and particularly metals, such as iron, platinum,
and palladium, of absorbing hydrogen gas. This chemist
designated the phenomenon by the name, occlusion of hydro-
gen by the metals. Palladium especially is distinguished by
the energy with which it absorbs hydrogen. It can condense
in its pores nine hundred times its own volume of the gas. A
palladium wire may be charged with hydrogen by arranging it in
a voltameter so that it constitutes the negative pole of a small
battery, the positive pole being a stout platinum wire. When
the current passes, the hydrogen set at liberty at the negative
pole (see page 71) is condensed in the palladium. This metal
undergoes at the same time a remarkable change. Its volume
augments and its density diminishes, but its metallic lustre
remains, as do also, to a certain degree, its tenacity and con-
ductibility for electricity; besides this it becomes magnetic.
There is thus formed a sort of alloy of palladium and hydro-
gen, containing about 20 volumes of palladium to 1 volume of
hydrogen reduced to the solid state. The density of this solid
hydrogen compared to that of water, according to the determi-
nations of Troost and Hautefeuille, is 0.62: it is a little greater
than that of lithium. Graham insisted upon the metallic char-
acter of hydrogen thus alloyed with palladium, and proposed
for it the name hydrogenium.
Chemical Properties.- Hydrogen is a combustible gas, and
the product of its combustion is water.
Experiments.-1. A lighted taper may be thrust into a rather
wide tube filled with hydrogen (Fig. 14). The gas takes fire
on contact with the flame, but the taper is extinguished in the
atmosphere of hydrogen. It may be relighted by withdrawing
it through the burning gas. The experiment shows at the
52
ELEMENTS OF MODERN CHEMISTRY.
same time that hydrogen is inflammable and that it is incapa-
ble of supporting combustion itself.
2. A gas-bottle, A (Fig. 12), is arranged for the preparation
of hydrogen, and water, zinc, and sulphuric acid are intro-

D
B
FIG. 12.
duced. The hydrogen evolved is made to traverse the tube
CB, which is filled with fragments of chloride of calcium; after
having been dried by this substance, which is very avid of
FIG. 13.
water, the gas escapes by the tube
a, the end of which is drawn out
to a point. The jet of gas is
lighted, and burns with a pale
flame. A bell-jar, D, is now
held over the burning jet, and
the sides of the glass soon be-
come covered with dew, the
drops of which unite and run
down to the edge of the jar. This
is water, and it is formed by the
combustion of the hydrogen; that
is, by its combination with the
oxygen of the air.
3. A jet of hydrogen may be
lighted by holding in it a tuft of
asbestos which has been dipped
in platinum black, that is, finely-divided platinum. The con-
densation of the hydrogen in the pores of the finely-divided
metal is so rapid that the platinum becomes heated to redness,
and then ignites the gas.

HYDROGEN.
53
4. A tube filled with hydrogen may be held in the vertical
position, bottom upwards, without the gas escaping rapidly by
the inferior opening. If the tube be inclined, the hydrogen
overflows and escapes upwards through the air. It may then
be received in a second tube held vertically above the first,
which is inclined more and inore (Fig. 13). The passage of
the gas into the upper tube can be demonstrated by approach-
ing to the latter a lighted taper, when the hydrogen will burn
with a faint explosion.
Before igniting or collecting hydrogen escaping from a gen-
erator, it should always be ascertained that the whole of the air
has been expelled, otherwise dangerous explosions may result.
5. The explosions may take place with the production of a
harmonious sound, if they are made to succeed each other



FIG. 14.
FIG. 15.
rapidly and at regular intervals. These conditions are realized
by burning a small jet of hydrogen in a somewhat large tube
(Fig. 15). The flame is drawn away from the jet by the draft
in the tube, but immediately recedes as the ascending hydro-
5*
54
ELEMENTS OF MODERN CHEMISTRY.
gen gas mixes with the air, at the same time producing a faint
explosion, and the rapid succession of these explosions produces
a musical tone.
The hydrogen condensed in palladium appears to have some
chemical properties different from those of gaseous hydrogen
(Graham). It combines in the dark and at ordinary tempera-
tures with iodine and chlorine; the direct union of ordinary
hydrogen with iodine is impossible, and with chlorine it takes
place at the common temperature only under the influence of
light. It seems, then, that hydrogen, when associated with
palladium, is more active than in the ordinary state.
OXYGEN.
Density compared to air.
Density compared to hydrogen
Atomic weight 0
1.1056.
16.
•
16.
Oxygen was discovered, in 1774, by Priestley, who obtained
а
FIG. 16.
or
it by heating red
precipitate
mercuric oxide.
Experiment.-
A tube, a (Fig.
16), contains a
concentrated so-
lution of the dis-
infecting powder
known as chlo-
ride of lime; a
small quantity
of the peroxide.
of cobalt, a com-
pound of oxygen
with the metal
cobalt, is then
introduced, and
the whole is gen-
tly heated. A
brisk efferves-
cence takes place,
and if a match


which has been just blown out and still presents a spark of fire
OXYGEN.
55
be thrust into the mouth of the tube, it is instantly relighted,
and burns with great brilliancy. This effect is due to a gas
which is being disengaged, and which, to use the expression of
Lavoisier, is eminently fitted to support combustion.
It is the gas to which that great chemist gave the name
oxygen. It is produced by a very simple reaction. Under
the influence of the peroxide of cobalt, the calcium hypochlorite
which is contained in the chloride of lime is converted into
calcium chloride and oxygen.
CaCl2O2
Oxygen.
CaCl2 + 02.
Calcium hypochlorite. Calcium chloride.
Preparation. Large quantities of oxygen may be prepared
by a process analogous to the preceding. When potassium
chlorate is heated, it is converted into potassium chloride, and
gives up all of its oxygen. To facilitate this decomposition, a
small quantity of manganese dioxide is mixed with the chlo-
rate. The part taken by the manganese dioxide is analogous
to that of the cobalt peroxide in the preceding reaction, and is
not thoroughly understood; it is most probable that it serves
to distribute the heat more regularly through the mass of
chlorate. If the temperature be sufficiently elevated, the de-
composition of the chlorate is complete, and takes place accord-
ing to the following equation:
KCIO³
Potassium chlorate.
KCI +
Potassium chloride.
03.
Oxygen.
The operation may be conducted in a glass retort, which
should be about one-third filled with the mixture of chlorate
and dioxide; to the beak of the retort is adapted a delivery-
tube, which dips under the surface of the water or mercury in
the trough (Fig. 17). The retort is then heated by an alco-
hol or gas lamp, and the chlorate melts and disengages its oxy-
gen with effervescence. Towards the close of the operation,
the heat is increased in order to decompose into potassium
chloride and oxygen any potassium perchlorate that may have
been formed by the union of a portion of the evolved oxygen
with some of the chlorate.
To make larger quantities of oxygen for filling the gas-
holders of laboratories, etc., a mixture of potassium chlorate
and manganese dioxide is heated in a sheet-iron or copper retort.
At a bright red heat manganese dioxide gives up a third
56
ELEMENTS OF MODERN CHEMISTRY.
of its oxygen, and is converted into the red oxide of manga-
nese.
3MnO
Manganese dioxide.
Mn O*
Red oxide of manganeso.
+
02.
Oxygen.
Oxygen can be cheaply manufactured on the large scale by
the process of Tessié du Mottay. This depends upon the for-
mation of sodium manganate by the action of air upon a heated

FIG. 17.
mixture of manganese dioxide and caustic soda, and the subse-
quent decomposition of this manganate at about 450° by a
current of steam, a decomposition which again sets at liberty
the oxygen absorbed by the manganese dioxide to form sodium
manganate. The operation is continuous.
Physical Properties.-Oxygen is a colorless, odorless, taste-
less gas; it is a little heavier than the air. If one volume of
hydrogen weighs 1, the same volume of oxygen, measured
under the same conditions of temperature and pressure, weighs
16. This is expressed by saying that the density of oxygen
compared to that of hydrogen is 16. A litre of oxygen weighs
1.437 gr. at 0° and under the normal pressure.
Until lately oxygen had been considered as a permanent gas.
By subjecting it to a pressure of 300 atmospheres and a tem-
perature of -29°, and then suddenly relieving the pressure,
Cailletet obtained it in the form of a cloud. Raoul Pictet
liquefied it by a pressure of 300 atmospheres and a temperature
OXYGEN.
57
of -140°. He attributes to liquid oxygen a density near that
of water,-about 0.9787.
Oxygen is but slightly soluble in water. A litre of water
dissolves 0.041 litre, or 41 cubic centimetres, at 0°; 0.032 litre
at 10°; 0.028 litre at 20°. The fractions 0.041, 0.032, 0.028,
represent the coefficients of solubility of oxygen in water at
the temperatures of 0°, 10°, and 200.
Chemical Properties.-Oxygen combines directly with most
of the other elements, and the union often takes place with
such energy that there results a great evolution of luminous
heat it gives rise to the phenomenon of combustion.
Experiments.—A cone of charcoal of which the point is red-
hot is plunged into a globe filled with oxygen (Fig. 18), and
immediately combustion takes place with great brilliancy. The
oxygen combines with the carbon, forming a colorless gas, which
is carbonic acid gas.
In like manner, sulphur and phosphorus burn in oxygen, the
first producing a colorless, irritating gas known as sulphurous


FIG. 18.
unio
FIG. 19.
acid gas, the second emitting thick fumes, which condense in
white flakes of phosphoric oxide.
A watch-spring may be drawn out into a spiral, and a small
piece of tinder attached to one end; after igniting the tinder,
the spiral is rapidly plunged into a bell-jar filled with oxygen,
and resting upon a plate containing a layer of water (Fig. 19).
The tinder burns energetically, and heats the end of the spiral
to redness; then the combustion of the iron itself commences,
and goes on with unparalleled brilliancy, and a production of
C*
58
ELEMENTS OF MODERN CHEMISTRY.
heat so intense that the oxide of iron formed melts and falls
in incandescent drops, which fuse themselves into the sur-
face of the plate, even after having traversed the layer of
water.
In the same manner, the combustion of the metal magnesium
may be effected in oxygen; it takes place with dazzling splen-
dor, and gives rise to the production of a white powder, which
is magnesia, or magnesium oxide.
The preceding experiments are examples of rapid combus-
tion. We have seen that solid substances, such as charcoal,
iron, and magnesium, become incandescent in combining with
oxygen: it is the phenomenon of fire. We have also seen that
vapors, like those of sulphur and phosphorus, become lumi-
nous in their combination with oxygen: this is the phenome-
non of flame.
But fire and flame are not necessary concomitants of the
union of bodies with oxygen. It is true that such union is
always accompanied by the production of heat; but often this
heat is not luminous; sometimes it is imperceptible to our
senses.
Thus iron, the combination of which with oxygen at a red
heat gives rise to such a brilliant combustion, may unite with
this gas at ordinary temperatures under the influence of
moisture. There is thus formed ferric hydrate, which consti-
tutes rust.
This oxidation of the iron, which takes place slowly, pro-
duces a feeble disengagement of heat, which is, however, imme-
diately dissipated. Such phenomena of oxidation are designated
by the name slow combustion.
The term combustion would then be synonymous with oxi-
dation did we not know, on the other hand, that all chemical
combination gives rise to the production of heat. If copper
be thrown into boiling sulphur, a vivid incandescence is pro-
duced, due to the union of the two bodies. Likewise antimony
and arsenic, when projected in fine powder into an atmosphere
of chlorine, unite with the latter body, producing a brilliant
combustion. It is seen that in these cases the production of
luminous heat indicates an energetic combination, but not an
oxidation.
Oxygen is one of the elements of the air; it is the cause
and the agent of all combustion, of all oxidation which takes
place in our atmosphere; and the oxygen fixes itself upon
OXYGEN.
59
burning bodies in such a manner that the product of the com-
bustion contains all of the matter of the combustible body and
all of the matter of the oxygen. This is one of the fundamental
truths of chemistry, and for its discovery not less than a cen-
tury and a half of work was required. The glory of the dis-
covery belongs to Lavoisier.
Ilis researches on combustion revealed to him the true
nature of the phenomena of respiration. The respiration of
animals is a slow combustion; it is the source of animal heat.
It gives rise to the formation of carbonic acid gas and water,
products of the complete oxidation through which must pass
those organic matters in the economy which no longer serve
the purposes of life, and all of which contain carbon and hy-
drogen.
The production of carbonic acid gas by the act of respira-
tion is easy to prove. It is only necessary to blow, by the aid
of a tube, the air contained in the lungs through clear lime-
water, which soon becomes milky from the formation of insolu-
ble carbonate of lime.
An annular jet of hydrogen through which a jet of oxygen
is forced constitutes what is known as the oxyhydrogen blow-
pipe, and is one of the most intense sources of heat known.
Platinum melts before it like wax, and iron and other combus-
tible metals burn brilliantly when introduced into its flame.
The flame of the oxyhydrogen blowpipe gives but little light,
but when it is projected upon a piece of lime, the latter becomes
heated to dazzling incandescence, constituting the Drummond
or calcium light.
OZONE, OR OXYGEN PEROXIDE.
002.
The repeated discharges of a good electric machine develop
a peculiar odor. This is due to the production of a body which
was discovered by Schönbein in 1840, and which he named
ozone (from ¿Zw, I smell).
Experiment. Some potassium permanganate is mixed with
barium dioxide in a mortar, the mixture transferred to a flask,
and moistened with sulphuric acid. The characteristic odor of
ozone immediately becomes perceptible, and a moistened paper,
impregnated with potassium iodide and starch and held in the
60
ELEMENTS OF MODERN CHEMISTRY.
neck of the flask, immediately assumes a blue color.¹ This effect
is caused by the ozone evolved.
This remarkable body is also formed under the following
circumstances.
1. By the passage of electric sparks through oxygen.—It is
sufficient to pass a series of electric sparks through oxygen
contained in a tube above a solu-
tion of iodide of potassium and
starch, in order to produce the
blue color caused by the ozone
(Fig. 20).
It has been noticed that the
largest quantity of ozone is pro-
duced when the passage of the
electricity through oxygen is ef-
fected, not by sparks, but by non-
luminous or obscure discharges
(Andrews and Tait, de Babo).
Dry and pure oxygen can be con-
verted into ozone in this manner.
But this conversion only takes
place partially, the ozone formed
remaining mixed with a large
excess of oxygen. A contraction
takes place at the moment the
oxygen is transformed into ozone.
These experiments prove that
ozone is condensed oxygen (Andrews and Tait, de Babo, Soret).
2. By the electrolysis of water.-When acidulated water
is decomposed by the battery current, the oxygen which is
disengaged at the positive pole contains small quantities of
ozone, and the proportion of the latter may be increased by
adding a considerable quantity of sulphuric or chromic acid to
the water.

FIG. 20.
3. During slow oxidation.-Some sticks of cleanly-scraped
1 Such a paper is called ozonoscopic. It is colored blue by the combina-
tion of the starch with the iodine set at liberty by the ozone. According
to Houzeau, it is preferable to use a delicate, wine-colored litmus-paper,
one-half of which is impregnated with potassium iodide. Ozone will change
the color of this half to blue, for, in decomposing the potassium iodide, it
forms potassium hydrate, and this restores the blue color to the litmus.
Under these conditions, the other half of the paper undergoes no change
in color, while it would be colored red by acid vapors, or blue by ammonia.
OZONE.
61
phosphorus are introduced into a bottle containing enough
water to just about half immerse them, and the whole is agi-
tated from time to time. In a short time the air in the bottle
will be charged with a small quantity of ozone.
According to Schönbein, who observed these facts, ozone is
produced during all slow combustions. Thus, when oil of tur-
pentine is exposed to the air under the influence of sunlight,
it is slowly oxidized, and in becoming resinified, it becomes at
the same time charged with a small quantity of ozone, which
dissolves in it.
4. By the decomposition of barium dioxide by sulphuric
acid. This decomposition gives rise to barium sulphate and
oxygen charged with a small quantity of ozone (Houzeau).
BaSO + H²0 + 0
H'SO+ Ba02
The barium dioxide is introduced in small portions into sul-
phuric acid contained in a flask, to the neck of which is fitted
a glass stopper pierced for the passage of the delivery-tube,
which is ground in (Fig. 21).

FIG. 21.
Properties of Ozone.-Ozone possesses an intense and pecu-
liar odor. At a temperature of 290° it is reconverted into
ordinary oxygen, the volume of which is greater than that
occupied by the ozone. It is then certainly condensed oxygen.
It has energetic oxidizing properties; it even oxidizes bodies
which possess only feeble affinities for oxygen. In the presence
of alkalies it combines with nitrogen, converting it into nitric
acid, which combines with the alkali.
It oxidizes silver at ordinary temperatures, converting it into
6
62
ELEMENTS OF MODERN CHEMISTRY.
the dioxide Ag²0". It instantly decomposes potassium iodide,
setting free the iodine. It is insoluble in water, but is entirely
soluble in oil of turpentine and oil of cinnamon, both of which
it slowly oxidizes. It oxidizes and destroys the greater number
of organic substances. In most of these oxidations only a third
part of the oxygen contained in ozone is active; the other two-
thirds become free in the form of ordinary oxygen, so that the
volume of the latter set free is exactly equal to that primitively
occupied by the ozone.
Hence it is concluded that 3 volumes of oxygen are con-
densed into 2 volumes by their conversion into ozone, and if
ordinary oxygen be the oxide of oxygen 00, ozone will be oxy-
gen peroxide 00' (Odling).
00 2 volumes of oxygen.
002 or
0—0
2 volumes of ozone.
This conclusion of Odling's concerning the nature of ozone,
has been verified by the determination of the density of this
body. Soret has established that when ozone diluted with oxy-
gen is absorbed by oil of turpentine or oil of cinnamon, there
is a diminution of volume sensibly double the increase of
volume noticed on subjecting the same gas to the action of
heat. He naturally concludes that the density of ozone is one
and a half times that of oxygen, or 1.658. These figures have
been confirmed by direct experiments upon the rapidity of
diffusion of ozone. It has been shown by the researches of
Graham that when diffusion between two gases takes place
through an opening, without the interposition of a diaphragm,
the rapidity of diffusion is inversely as the square roots of the
densities of the gases. Soret has demonstrated that the
rapidity of diffusion of ozone is notably greater than that of
chlorine, and very near but somewhat less than that of car-
bonic acid. It results that its density is less than that of
chlorine, and a little greater than that of carbonic acid, which
is 1.525; this confirms the density 1.658.
An important property of ozone is its reduction by hydrogen
dioxide, and the simultaneous decomposition of the latter com-
pound. The products are ordinary oxygen and water.
002 + H2O²
2(00) + H2O
Ozone. Hydrogen dioxide. Ordinary oxygen.
Water.
THE ATMOSPHERE.
63
ATMOSPHERIC AIR.
The air is a mixture of oxygen and nitrogen. It also con-
tains traces of carbonic acid gas and a variable proportion of
vapor of water.
Its composition was established by Lavoisier by an experi-
ment that has become celebrated. Having heated mercury in
a limited quantity of air to a temperature near its boiling-point
for several days, he observed the formation of a red powder, a
combination of the mercury with oxygen. On the termination
of the experiment, he found that the volume of the air had
diminished about one-sixth. He carefully collected the oxide
formed, introduced it into a small retort, and heated it to red-
ness. He thus obtained a gas "eminently qualified to support
combustion and respiration," and the volume of which was
sensibly equal to that of the gas that had disappeared. This
gas he named oxygen. He mixed it with the irrespirable resi-
due from the first experiment, which would not support com-
bustion, and so reconstituted atmospheric air. The composition
of the latter was thus established by analysis and synthesis.
This experiment was infinitely more instructive than that
undertaken by Scheele at about the same time. The great
Swedish chemist only absorbed the oxygen of the air by the
alkaline sulphides. The nitro-

gen remained as residue, but
the oxygen combined with the
sulphide could not be again.
separated.
However, neither one nor
the other of these methods
could give the exact propor-
tion according to which the
oxygen and nitrogen are mixed
in the atmosphere. This has
been deduced from the follow-
ing experiments.
FIG. 22.
Experiments.-1. Into a small bent tube closed at the
upper end, filled with mercury and inverted in a vessel of the
same metal, are passed 100 volumes of air (Fig. 22). A
small piece of phosphorus is then introduced and brought
into the upper limb, where it is heated by the aid of a spirit-
lamp. It takes fire, and in burning consumes all of the
64
ELEMENTS OF MODERN CHEMISTRY,
oxygen of the 100 volumes of air. The operation has termi-
nated when the flame of the phosphorus vapor has extended
down to the column of mercury. The residual gas is then
allowed to cool, and on being measured is found to be
reduced to 79 volumes. It is nitrogen.
2. The absorption of oxygen by phosphorus will take
place in the cold, if a long stick of this substance be in-
troduced into a determined volume of air contained in a
graduated tube. The experiment requires several hours,
and gives the same result as the preceding.
3. 100 volumes of air are measured into a graduated
tube on the mercury-trough. A concentrated solution
of potassium hydrate is introduced, and then some pyro-
gallic acid, a white, crystalline substance employed in
photography; the whole is then rapidly agitated, the
extremity of the tube being closed by the thumb.
The alkaline solution is immediately blackened by the
destruction of the pyrogallic acid. All of the oxygen is
rapidly absorbed, and when the tube is opened, under
the surface of the mercury, the 100 volumes of air are
found reduced to about 79 volumes.

FIG. 23.
FIG. 24.
4. There is another method capable of still greater precision
Fig. 23 represents a Bunsen's eudiometer; it is a stout glass
tube about 60 centimetres long and 2 centimetres in diameter.
Two platinum wires are hermetically scaled into the upper ex-
tremity through the whole thickness of the glass. Each ter-
THE ATMOSPHERE.
65
minates exteriorly in a small loop, and on the interior follows
the curve of the end nearly to the centre, so as to leave an
interval of about 1 centimetre between the extremities of the
two wires. The tube is graduated in millimetres, and the ca-
pacity of each division is known. It is filled with mercury and
inverted upon a small trough. 100 volumes of air and 100
volumes of hydrogen are then introduced. One of the plati-
num loops is then put into communication with an electrical
conductor, and the other with the earth, and a spark is passed
through the mixture (Fig. 24). A flash appears in the tube,
and all of the oxygen of the 100 volumes of air has combined
with hydrogen to form water. There thus results a vacuum,
which is filled by the mercury, and in place of 200 volumes of
gas introduced into the eudiometer, we find, all corrections being
made, only 137.21 volumes of a mixture of hydrogen and
nitrogen.
62.79 volumes have then disappeared to form water, and
this water contains all of the oxygen contained in 100 volumes
of air; as each volume of this oxygen must consume 2 vol-
umes of hydrogen, it follows that the 62.79 volumes which
have disappeared must have contained 20.93 volumes of
oxygen and 41.86 volumes of hydrogen.
Hence the 100 volumes of air introduced into the eudiom-
eter contained 20.93 volumes of oxygen and 79.07 volumes of
nitrogen.
Such is the composition of the air by volume. As nitrogen
is lighter than oxygen, these volumetric relations do not express
the composition of the air by weight. This was determined
very exactly by Dumas and Boussingault in the following
manner.
A globe, A (Fig. 25), having a capacity of 15 or 20 litres,
and fitted with a brass cap and stop-cock, R", by which it may
be connected with an air-pump, is joined to a hard glass tube,
BB', having a stop-cock at each end, R and R', and filled with
metallic copper. The air is exhausted from the globe and tube,
and the weight of each is then accurately determined.
The tube BB' is placed in a combustion-furnace, and by its
extremity B' is connected with the tubes K, I, H, G, F, È, D,
C. The tube with bulbs C contains a solution of caustic po-
tassa; the tubes D and E are filled with pumice-stone imprèg-
nated with caustic potassa, and the tubes F and G with frag-
ments of solid caustic potassa; the bulbs H contain sulphuric
6*
66
ELEMENTS OF MODERN CHEMISTRY.
acid, and the last tubes, I and K, are filled with fragments of
pumice-stone saturated with sulphuric acid. The potassa serves
R' B
B' R
H
R"
QPIN AMENA PITA I
FIG. 23.
to remove from the air
the small quantity of
carbonic acid gas which
it contains, and the sul-
phuric acid absorbs the
moisture.
The tube filled with
copper is now heated to
redness, its stop-cocks
being open, and the
stop-cock of the globe is
gradually opened. Air
immediately enters, but
it is first obliged to tra-
verse the series of tubes,
where it is deprived
of its carbonic acid
gas and vapor of water,
and also the tube filled
with incandescent cop-
per, which absorbs the
oxygen. It is then pure
nitrogen which enters
the globe. The experi-
ment has terminated
when the tension of the
gas in the globe is equal
to the exterior pressure,
that is, when no more
air enters.
The stop-
cock R" is now closed.
The tube and globe are
allowed to cool, and are
weighed separately.
The increase in weight
of the globe gives the
weight of the nitrogen
which has entered.

The increase in weight of the tube, which was first weighed
exhausted of air, gives the weight of the oxygen which has
THE ATMOSPHERE.
67
combined with the copper, plus the weight of the nitrogen
remaining in the tube at the close of the experiment. The
weight of this nitrogen is determined by exhausting the tube
and weighing a third time. The difference between the second
and third weighings indicates the weight of the nitrogen re-
maining in the tube at the end of the experiment, and this
weight added to that of the nitrogen contained in the globe
constitutes the total weight of nitrogen in the air analyzed.
The weight of the oxygen is given by the difference between
the third and first weighings of the tube.
By this method Dumas and Boussingault found that 100
parts of air contain by weight
Oxygen
Nitrogen
23.13
76.87
These two gases are simply mixed in the air; they do not
exist there in a state of combination; and the proportions of
the mixture are universally the same with very slight varia-
tions. At the summits of the highest mountains, at the centres
of the continents, and over the vast expanse of the seas, the
air has been shown to be nearly equally rich in oxygen. From
a comparison of a great number of analyses, Regnault has cs-
tablished that as a rule the percentage of oxygen only varies
from 20.9 to 21.0; air which has been collected on the open
sea and close to the surface of the water, has been found to
contain a somewhat smaller amount (20.6), a circumstance
which may be attributed to the dissolving action of the water.
Nitrogen and oxygen are by far the most abundant con-
stituents of the atmosphere; among the substances which are
contained in small proportion must be mentioned particularly
carbonic acid gas and vapor of water.
Carbonic Acid Gas and Vapor of Water.-If lime-water
be poured into a flat dish and exposed to the air, in a few
hours its surface will be found covered with a white pellicle
formed of little crystals of calcium carbonate.
This experiment demonstrates the presence of carbonic acid
gas in the atmosphere. The watery vapor may be condensed
by exposing to the air a glass vessel containing a mixture of ice
and salt. The sides of the vessel soon become covered with a
layer of frost, resulting from the solidification of the water which
has been condensed from the air by the cool surface of the glass.
The exact quantities of carbonic acid gas and vapor of water
68
ELEMENTS OF MODERN CHEMISTRY.
contained in the air may be determined by drawing the latter
through tubes containing sulphuric acid and caustic potassa.
The aspiration is obtained by means of a bottle or a tin vessel,
V (Fig. 26), filled with water. On opening the stop-cock r,
mm

B
D
E
F
V
MAIDEN
FIG. 26.
the water runs out, and air is drawn in through the tubes F
and E, filled with fragments of pumice-stone wetted with sul-
phuric acid, then through D and C, containing pumice-stone
impregnated with caustic potassa, and finally B, which is like
the first two. These tubes increase in weight from the absorp-
tion of vapor of water in the first two, and carbonic acid in
the others. The difference in weight of the tubes F and E
before and after the experiment gives the proportion of con-
densed water; the difference of D, C, and B gives the propor-
tion of carbonic acid gas. The volume of air is equal to that
of the water which has run out of the aspirator.
According to the experiments of Theodore de Saussure, the
quantity of carbonic acid gas contained in the air varies from
4 to 6 ten-thousandths. It is increased in inhabited places.
It is greater at night than during the day, a circumstance that
must be attributed to the influence of vegetation. It is dimin-
3
THE ATMOSPHERE.
69
ished after a rain, and is found in its minimum proportion
above the surface of large lakes.
The sources of this carbonic acid gas are various. In cer-
tain regions fissures in the earth disengage large volumes; vol-
canoes emit immense quantities; certain spring waters are
supersaturated, and disengage it in abundance when they reach
the surface of the earth. But the greater portion is produced
by the phenomena of combustion which take place on the
earth's surface; and among these phenomena must be included
respiration, which is a slow combustion.
Experiment. If by the aid of a glass tube, a (Fig. 27), air
from the lungs be blown through lime-water, the latter becomes
clouded, by the formation
of calcium carbonate. The
carbonic acid gas thus
fixed by the lime comes
from the respiration, which
is an abundant source of

that gas.
Does carbonic acid gas
accumulate indefinitely in
the atmosphere? No. Re-
jected and excreted by ani-
mals, it serves for the res-
piration of plants. The
green parts of vegetables.
possess the power of de-
composing this gas under
the influence of the sun's
light. The carbon is fixed,
and serves for the nu-
trition of the plant;
FIG. 27.
the oxygen is rejected, if not wholly, at
least in great part. This truth is one of the most important
achievements of the science of the last century. It is due to
the successive labors of Priestley, Bonnet, Ingenhouz, Senne-
bier, and Theodore de Saussure,
Independently of carbonic acid gas and vapor of water, air
contains other matters mixed with or suspended in it in very
small quantities. Among these must be mentioned:
1. Traces of ammonia, or rather of ammonium carbonate.
These substances are dissolved by rain-water, and play an
important part in vegetation.
70
ELEMENTS OF MODERN CHEMISTRY.
2. A trace of hydrogen carbide (Boussingault).
3. A small quantity of nitric acid in the form of ammonium
nitrate. It is supposed that nitric acid is formed in the air by
the direct union of the nitrogen and oxygen under the influ-
ence of atmospheric electricity. Schönbein asserts that the
air contains traces of ammonium nitrite :
(NH*)NO
4. A body which possesses the property of imparting a blue
color to papers saturated with starch and potassium iodide.
It is held, and not without reason, that this substance is ozone.
The phenomenon would also be caused by the presence of
traces of nitrous vapors or chlorine in the air; but Andrews
has shown that air contains a principle which decomposes po-
tassium iodide, and loses this property when it is brought to a
high temperature. This fact can be explained if the air con-
tain ozone, which is destroyed by heat; it cannot be explained
if it contain chlorine or nitrous vapors. Besides, the air con-
tains only very slight traces of ozone, which vary greatly;
often none is present. The relative proportion of ozone pres-
ent is approximately estimated by the greater or less intensity
of the blue color produced upon ozonoscopic paper.
5. Solid particles suspended in the air and carried to a dis-
tance by the winds. In perfectly calm air these corpuscles are
deposited, forming a dust of which the composition is very
variable. It contains various microscopic vegetable and animal
germs (Pasteur).
WATER.
Vapor density compared to air.
0.623.
Vapor density compared to hydrogen
Molecular weight H20
1
9.
18.2
Water is the product of the combination of hydrogen and
oxygen; its composition was established by Lavoisier in 1785.
1 The density of vapor of water compared to that of hydrogen is 9; that
is, if the weight of 1 volume of hydrogen be represented by 1, the weight
of 1 volume of vapor of water will be 9; in other words, vapor of water is
nine times more dense than hydrogen under the same conditions of tem-
perature and pressure.
2 The weight of the molecule or the molecular weight expresses the
weight of 2 volumes of vapor, if the weight of 1 volume of hydrogen be
represented by 1.
WATER.
71
The combination takes place exactly in the ratio of 2 volumes
of hydrogen to 1 volume of oxygen, as demonstrated by the
following experiments.
1. Analysis of Water by Electrolysis.-Water slightly acid-
ulated with sulphuric acid is introduced into the vessel C
(Fig. 28), through
the bottom of which
rise two platinum
wires. These wires
are hermetically
scaled in the walls
of the glass, and the
free exterior ex-
tremities are con-
nected with
poles of a galvanic
battery. The cur-
rent passing through
the acidulated liquid
decomposes

the
the
water,' and bubbles
FIG 28.
of gas are formed and rapidly rise from the two platinum wires
which constitute the poles. If two small tubes filled with
water be inverted over these wires, the gases may be collected,
aud it will be found that the gas disengaged at the negative
pole is sensibly double in volume that disengaged at the posi-
tive. The first is hydrogen, and the second oxygen, and the
proportion in which these gases are set free would be exactly
that of 2 to 1, were it not that a small quantity of oxygen re-
mains dissolved in the acid liquid, or, under certain condi-
tions, combines with a portion of the water surrounding the
negative pole to form a trace of hydrogen dioxide, as will be
mentioned farther on.
This experiment of the decomposition of water by the pile
was made for the first time, in 1801, by two English physi-
cists, Nicholson and Carlisle.
1 Under these conditions, it is really the sulphuric acid which is decom-
posed; II2S04 breaks up into II2, which is liberated at the negative pole,
and SO4, which separates at the positive pole, and is at once decomposed
into S03 and 0. The O is disengaged, and the S03 in the presence of the
water becomes again hydrated, reforming sulphuric acid. S0³ + 11²0 = -
HI²SO¹. The electrolytic action is thus confined to the sulphuric acid,
which alone is decomposed.
72
MODERN CHEMISTRY.
ELEMENTS OF MODER
2. Eudiometric Synthesis.-The composition of water can
be established by synthesis, that is, by the combination of the
two elements, hydrogen and oxygen. The experiment, which
is made in an eudiometer, has already been described (page 28).
It demonstrates that the two gases combine in the exact ratio
of 2 volumes of the first to 1 of the second, and that these
3 volumes of gas are condensed into 2 volumes of vapor of
water.
These experiments establish the volumetric composition of
water; its composition by weight can be deduced from them,
the densities of hydrogen and oxygen being known; for the
weighable matter of 2 volumes of hydrogen being added to the
weighable matter of 1 volume of oxygen, it is only necessary
to add twice the weight of 1 volume of hydrogen to the weight
of 1 volume of oxygen in order to determine the weight of 2
volumes of vapor of water. That is to say, the ratio by weight
in which hydrogen combines with oxygen to form water is that
of double the density of hydrogen (the weight of 2 volumes of
H) to the density of oxygen (the weight of 1 volume of O).
This ratio is
2 X 0.0693 0.1386 1
1.1056
1.1056 8
It may be deduced in a more simple manner by a com-
parison of the densities of hydrogen and oxygen. If 1 volume
of hydrogen weighs 1, 1 volume of oxygen weighs 16; the
weight of 2 volumes of hydrogen will then be 2, and it will be
seen that the two gases unite, by weight, in the ratio of
2 1
100
16 8
18 grammes of water then contain 16 grammes of oxygen
and 2 grammes of hydrogen. This composition, which can be
determined only in an approximative manner by a compari-
son of the densities, owing to the difficulties in the methods
of weighing gases, has been established in the most rigorous
manner by Dumas, in an experiment which has become classic,
and will now be described.
3. Synthesis of Water by the Gravimetric Method. In order
to determine the composition of water by synthesis it is suffi-
cient to combine an indeterminate quantity of hydrogen with
a precisely determined weight of oxygen, and to weigh exactly
the water formed. By subtracting from this latter weight that
WATER.
73
of the oxygen contained in the water, the weight of the hydro-
gen which has com-
bined with that oxy-

gen is obtained.
In order to thus
combine hydrogen
with oxygen, it is
convenient to make
the former gas react
upon an oxidized
body which will read-
ily yield its oxygen
to the combustible
gas. Cupric oxide, or
black oxide of cop-
per, CuO, first sug-
gested by Gay-Lus-
sac, and employed for
this purpose by Ber-
zelius and Dulong,
fulfils these condi-
tions. Although un-
decomposable by heat
alone, it is readily re-
duced by hydrogen
when heated in an at-
mosphere of that gas.
Dumas employed the
apparatus represent-
ed in Fig. 29.
Hydrogen is pre-
pared by the action
of dilute sulphuric
acid upon zinc, and
is purified by being
conducted through a
series of U tubes, the
first containing frag-
ments of glass wet
with a solution of lead
acetate, the second,
FIG. 29.
fragments of glass wet with a solution of silver sulphate, and
D
7
74
ELEMENTS OF MODERN CHEMISTRY.
the third, pumice-stone, impregnated with caustic potassa.
The lead acetate retains hydrogen sulphide; the silver sulphate
absorbs hydrogen arsenide, and the potassa absorbs any traces
of carbides of hydrogen.
The hydrogen thus purified is dried by passage through an-
other series of U tubes, the first containing calcium chloride,
and the others pumice-stone saturated with sulphuric acid. The
latter tubes are cooled by being surrounded with ice. The gas
is lastly passed through a smaller tube containing phosphoric
oxide. The weight of this tube must remain constant during
the whole of the experiment. It is called the witness-tube.
The pure and dry hydrogen now passes through a green
glass bulb, which contains pure cupric oxide. The weight of
this bulb, together with the oxide which it contains, is deter-
mined with care. The receiver B', as well as the U tubes
which terminate the apparatus, are also accurately weighed.
When the whole of the air contained in the apparatus has
been expelled by the hydrogen, the flask is heated and the
cupric oxide is reduced. Water is formed and is in great part
condensed in the liquid state in the receiver, but a portion of
the vapor remains uncondensed and is carried off by the excess
of hydrogen. This vapor is retained in the second series of
U tubes, which contain calcium chloride and pumice-stone satu-
rated with sulphuric acid. When the reduction has almost
terminated, the bulb is allowed to cool, the current of hydro-
gen being continued; this gas is finally displaced by a current
of air, and the weighings are then made.
The weight of the bulb has decreased by that of all of the
oxygen which has been taken from the oxide of copper by the
hydrogen, and which now exists in the water formed.
The weight of the receiver and the condensing apparatus con-
nected with it is increased by the weight of all the water formed.
By subtracting the weight of the oxygen from that of the
water we find the weight of the hydrogen.
By the aid of this rigorous method Dumas has found that
100 parts by weight of water contain
Hydrogen.
Oxygen
These numbers are in the exact ratio of
Hydrogen
Oxygen.
•
11.11
88.89
100.00
1
8
WATER.
75
Physical Properties.-Pure water has neither taste nor
odor. It is limpid and colorless. It occurs in three states in
nature; during the colds of winter it is solid. Ice, snow, frost,
sleet, and hail are the different forms which it assumes in this
state. The temperature at which ice melts is one of the stand-
ard points in the thermometric scale. To this temperature
corresponds the 0 of the centigrade scale, which is adopted in
this work.
Snow is composed of an agglomeration of little crystals;
these are hexagonal prisms, which often present the forms rep-
resented in Fig. 30.

1
Q
3
4
التا
5
•*****
FIG. 30.
At the moment of freezing, water expands, and its density
is then less than that which it possesses in the liquid state.
The density of ice is 0.93. Water contracts in volume from
0 to +4°, and presents its maximum density at the latter tem-
perature. Its density at this point is chosen as the unit of
comparison for the densities of solid and liquid bodies.
Water and even ice are continually emitting invisible vapors
which mix with the air, and are, as it were, dissolved in it.
This vaporization takes place more actively as the temperature
is raised.
The air is said to be saturated with vapor at any given tem-
perature when it refuses to take up any more vapor at that
temperature. Under these conditions, if the temperature be
lowered, a portion of the vapor is condensed in fine drops,
which remain suspended in the air in the form of mist or visi-
ble vapor. The point at which the moisture of the air is con-
densed is called the dew-point.
Water begins to boil when its vapor acquires sufficient ten-
sion to overcome the atmospheric pressure. This is the boil-
ing-point, and under a pressure of 0.760 metre corresponds to
100° of the centigrade scale.
76
ELEMENTS OF MODERN CHEMISTRY.
Chemical Properties. Water is partially decomposed by
the highest temperatures at our command. On pouring melted
platinum into an iron mortar containing water, Grove observed
a disengagement of bubbles composed of an explosive mixture
of oxygen and hydrogen. According to H. Sainte-Claire De-
ville, vapor of water undergoes a partial decomposition, which
he calls dissociation, when exposed to a temperature between
1100 and 1200°. In order to collect the gases resulting from
this decomposition it is necessary to separate them before they
have reached a part of the apparatus where a less elevated
temperature would permit their recombination. For this pur-
pose Deville directed a current of steam through a porous clay
tube, a (Fig. 31), surrounded by a tube of glazed porcelain, b,

ር
FIG. 31.
which was heated to whiteness in a powerful furnace. A cur
rent of carbonic acid gas was passed through the annular space
between the two tubes, by means of the tube c. The vapor of
water was decomposed by the heat into hydrogen and oxygen;
but these two gases separated from each other: the hydrogen,
being the more diffusible, passed in great part through the
porous tube, while the oxygen was delivered by the interior
tube, together with a small quantity of carbonic acid gas, which
entered by diffusion. The gases evolved by the two tubes were
collected in a small jar filled with a solution of caustic potassa
by which the carbonic acid gas was absorbed, and there re-
mained an explosive mixture of hydrogen and oxygen.
Water is decomposed by an electric current, as already seen.
WATER.
77
It is likewise decomposed by many of the elements, metallic
and non-metallic, which combine with one or the other of its
component elements. Thus, chlorine decomposes it at a red
heat, uniting with the hydrogen to form hydrochloric acid, and
setting free the oxygen; also under the influence of light at
ordinary temperatures. A number of the metals decompose
water, liberating the hydrogen.
Iron decomposes it at a red heat, taking up the oxygen and
setting free the hydrogen; potassium and sodium, as we have
seen in the case of the latter metal, produce the same effect at
ordinary temperatures.
Many compound bodies seize upon the elements of water,
and are decomposed by it. Such are the chlorides of phos-
phorus and antimony. In these reactions, which will be
studied farther on, the hydrogen of the decomposed water
unites with the chlorine, the oxygen with the other element.
We have already noticed the action of water upon the non-
metallic and metallic oxides. It combines with many of these
compounds, forming either acids or metallic hydrates.
Certain of these reactions are worthy of reconsideration. It
is especially important to fully appreciate the part played by
the water which enters into them.
When potassium oxide becomes hydrated to form caustic
potassa, the reaction takes place by a double decomposition,
which may be expressed by the following equation:
(1) K}
}
Potassium oxide.
H
H
+
H
}
K
O
H
}0 +
+ }
10
Water.
K
Potassium hydrate. Potassium hydrate.
It will be seen that both the potassium oxide and the water
are converted into potassium hydrate by the exchange of an
atom of potassium for an atom of hydrogen. Potassium hydrate
is, as it were, derived from water by the substitution of an atom
of potassium for an atom of hydrogen. This substitution takes
place directly when water is decomposed by potassium.
2H2O + K² 2KOH + H2
(2)
The potassium hydrate in its turn may lose the remaining
atom of hydrogen; if it be heated with potassium, this hydro-
gen is displaced, and potassium oxide is formed.
(3) 2KOH + K2
Potassium hydrate. Potassium.
2K20
+ H2
Potassium oxide.
Hydrogen.
7*
78
ELEMENTS OF MODERN CHEMISTRY.
It will be seen from what precedes that, starting with water,
we may form potassium hydrate (2), potassium oxide (3), and
this again may be converted into potassium hydrate (1). The
three compounds are then closely related. Each contains 1
atom of oxygen combined with 2 atoms of another body, hy-
drogen or potassium, and the relation is clearly expressed in
the following formulæ :
H}
O
Water.
K
O
H
K
K
}
Potassium hydrate. Potassium oxide.
If hypochlorous oxide, Cl2O, be poured into water, it is in-
stantly dissolved and converted into hypochlorous acid. The
reaction is expressed in the following equation:
Cl
H
+
0
H
Hypochlorous oxide.
Water.
H
Cl
}0 +
Cl
H
}
0
Hypochlorous acid.
Hypochlorous acid.
Both the hypochlorous oxide and the water are converted
into hypochlorous acid by the exchange of an atom of hydro-
gen for an atom of chlorine, so that the hypochlorous acid
may be said to represent water in which 1 atom of chlorine is
substituted for an atom of hydrogen.
Thus, by their atomic constitution both potassium hydrate
and hypochlorous acid are closely related to water. But on
comparing them together they are found to differ widely in
their properties, both from each other and from water itself.
How could it be otherwise with bodies containing elements as
unlike as potassium and chlorine? Indeed, the distance which
separates potassium hydrate and hypochlorous acid is not
greater than that which separates potassium and chlorine.
Thus, a difference of elements may imply a marked difference of
properties between bodies which otherwise present a similar con-
stitution, and which may be said to belong to the same type.
Water is one of these types. Its constitution serves as a
sort of model for that of a multitude of compounds. It will be
sufficient to reconsider the examples already cited, and we may
say that water, potassium hydrate, potassium oxide, hypochlo-
rous acid, and hypochlorous oxide belong to the water type.
CI
CI
}0
Hypochlorous
oxide.
TYPE.
Cl
0
H
H}O
Water.
Hypochlorous
acid.
K
H
} o
Potassium
hydrate.
K
Ko
} 0
Potassium
oxide.
WATER.
79
The preceding considerations give but a limited idea, but
one sufficient for the present, of the rôle played by water in
chemical phenomena. This role is one of great importance,
for water takes part in an immense number of reactions, either
by its decomposition, its formation, or its combination.
Water presents still another mode of action. It dissolves
very many bodies, and this solvent action is exerted upon
gases, liquids, and solids.
Solvent Properties of Water.-When a gas dissolves in
water, it changes its state, it becomes itself liquid, and in lique-
fying it evolves heat. In the same manner a solid body be-
comes liquid by the act of solution, but in order to become
liquid it must absorb heat. Consequently, the solution of a
gas in water takes place with a production of heat; that of a
solid body takes place with a lowering of temperature, or, to
use a common expression, a production of cold.
But sometimes this physical phenomenon of the solution of
a solid body in water, that is, its liquefaction and diffusion in
the liquid, is complicated by a chemical action.
Experiment. If water be poured upon fused and powdered
calcium chloride, the salt is instantly dissolved with a produc-
tion of heat. This heat is the evidence of a chemical com-
bination, and the water has indeed combined with the calcium
chloride; if now the solution be sufficiently evaporated, it will
deposit fine transparent crystals of hydrated calcium chloride.
The water contained in these crystals, and which is necessary
for their formation, is what is called water of crystallization.
It is contained in definite proportions, and is retained in the
crystals by affinity. For this reason the combination of water
with calcium chloride is accompanied by a production of heat.
If these crystals of calcium chloride be dissolved in water,
they disappear, and the temperature of the liquid is depressed.
The physical phenomenon of the solution of a solid body in
water can thus be separated from the chemical phenomenon
of its combination with that liquid.
Natural State of Water.-Water is not met with in a pure
state in nature. Whether it has rested upon or has flowed over
the surface of the soil, whether it has fallen in the form of rain,
mist, or dew, or whether it has just issued from its subterranean
passages, it always contains various matters in solution.
It takes up the gases from the atmosphere, and also certain
bodies which it there finds suspended or in vapor. On the
80
ELEMENTS OF MODERN CHEMISTRY.
surface or in the bosom of the earth it dissolves the soluble
substances which it encounters. Hence the composition of
natural water presents great variations, according to the origin
of the water and the localities where it has collected, or the
soils through which it has travelled. In general, meteoric
waters, that is, those which result from the condensation of
the aqueous vapor diffused through the atmosphere, arc more
pure than those which have collected upon the earth's surface.
The latter present in their physical and chemical properties, in
their composition, and in their action upon the animal econ-
omy, such differences that they are classified in several groups.
Soft or potable waters are distinguished from hard waters.
The first are such as hold only small quantities of foreign mat-
ters in solution, and are essentially fit for domestic use. The
second are too highly charged with saline matters, and princi-
pally the salts of calcium, to be fit for such purposes. Good
potable water should be cool, limpid, without odor, should have
a faint but agreeable taste, which should be neither insipid,
saline, nor sweet, and should cook and soften vegetables and
dissolve soap.
The purest water is not necessarily the best.
Thus distilled water, rain-water, and that coming from the
melting of ice and snow, although more pure, are less salubrious
than good spring or river water.
Good potable water should be aerated, that is, it should hold
in solution the gases contained in the atmosphere: oxygen,
nitrogen, and carbonic acid. Rain-water takes from the atmos-
phere a proportion of oxygen, and especially of carbonic acid
gas, much greater than that in which these gases are contained
in the air. This must be so, for Dalton has shown that the
solvent action of water upon a gaseous mixture is measured for
each gas by the product of its coefficient of solubility and the
figure expressing the proportion of that gas in the mixture.
These gases are driven out of water by boiling.
The following figures give the proportions of the atmospheric
gases expelled by boiling from a litre of water from the Seine,
in the month of January, and also the proportions contained in
a litre of rain-water (Peligot):
Carbonic acid gas
Nitrogen
Oxygen
•
Water of the Seine.
•
Rain-Water.
22.6 cubic centimetres.
•
21.4
0.5 c. c.
15.1
1.77
64.47
10.1
7.4
33.76
54.1
23.0
100.00
WATER.
81
It is seen that the running water contains a larger amount
of all of the gases than rain-water, and a notably larger pro-
portion of carbonic acid.
Solid Matters dissolved in Water.-Soft waters generally
contain a small proportion of fixed matters, among which are
certain salts of calcium and magnesium, certain alkaline salts,
silica, and organic matters.
The calcium salts are the carbonate and sulphate, and some-
times traces of the chloride, nitrate, and phosphate.
Calcium carbonate, or carbonate of lime, is almost insoluble
in pure water, but dissolves readily in water charged with
carbonic acid gas; in such solutions it exists as dicarbonate.
When water thus charged with calcium dicarbonate is boiled,
that salt is decomposed, carbonic acid gas is disengaged, and
neutral calcium carbonate is precipitated.
precipitated. When the propor-
tion of calcium dicarbonate contained in spring-water is large,
it may happen that as the water loses carbonic acid gas the
calcium carbonate is deposited at ordinary temperatures. This
effect is favored by the tumultuous movements to which spring-
water is subjected either in flowing over an inclined bed or in
conducting-pipes. The carbonate then forms a crystalline de-
posit, which incrusts the interior walls of the pipes and, in
general, whatever objects may be plunged into such waters,
which for this reason are called incrusting or petrifying
waters.
The presence of small quantities of calcium dicarbonate in
drinking-water may be considered as a good condition, from a
hygienic stand-point, for the system needs calcareous salts for
the development and nutrition of the bony structures.
Calcium sulphate, or sulphate of lime, exists in solution in
many waters, especially in spring and well waters. When the
proportion does not exceed fifteen or twenty centigrammes per
litre, such water may be used without inconvenience for do-
mestic purposes. Water largely charged with calcium sulphate
is called selenitous water; it does not become clouded on ebul-
lition. Like all other strongly calcareous water, it does not dis-
solve soap without first forming a flocculent precipitate. Salts
of barium produce with such water an abundant white precipi-
tate of barium sulphate, which is insoluble in nitric acid. Such
water is unfit for economic purposes.
In general, the proportion of calcareous salts in potable water
should not exceed five or six decigrammes per litre; water
D*
82
ELEMENTS OF MODERN CHEMISTRY.
containing more than this is difficult to digest, and is called
hard water.
Mineral or Medicinal Waters.-These are waters that by
virtue of their temperature or chemical constituents exercise
a special action upon the animal economy, and consequently
have a therapeutic value.
They are cold or warm. They are called warm when their
temperature at the moment of emergence is above 12 or 15°.
Of course their temperatures vary greatly, covering the whole
thermometric scale from 25 to 100°. There are numerous hot
springs in California, Colorado, and Virginia. The tempera-
ture of the Grand Geyser in Iceland is even above 100° in the
depths of the tube from which it issues. According to their
chemical constituents, mineral waters are classified in a number
of characteristic groups, distinguished either by the predomi-
nance of certain constituents, or by the presence of principles
particularly active. These groups are as follows:
Acidulous or gaseous waters, characterized by the presence
of free carbonic acid.
Alkaline waters, characterized by the presence of a greater or
less proportion of sodium dicarbonate, or of an alkaline silicate.
Chalybeate waters, holding a salt of iron in solution.
Saline waters, or those containing certain neutral salts.
Sulphur waters, characterized by the presence of hydrogen
sulphide or other soluble sulphide.
On arriving at the surface of the earth, certain of these
mineral waters undergo a change in chemical constitution.
Such are the sulphur waters which absorb oxygen, as will be
noticed presently. Those containing free carbonic acid lose a
part of their gas, and it often happens that some of the car-
bonates held in solution by an excess of carbonic acid become
insoluble, and are deposited after the escape of that excess.
This is the principal cause of the deposits which form in the
basins and conducting-pipes of many mineral waters. These
deposits vary greatly in composition; sometimes they are floc-
culent or pulverulent, and collect in the form of mud; some-
times they form hard concretions or scales. Calcium and
magnesium carbonates, ferric hydrate, alumina, and silica are
the most ordinary constituents of such deposits. Besides these,
arsenic, various metallic oxides, and materials which it would
be difficult to detect in the water itself, are sometimes concen-
trated, as it were, in these deposits. Thus, arsenic is detected
WATER.
83
much more readily in the ochrey deposits around a ferruginous
spring than in the water of the spring itself.
ACIDULOUS OR GASEOUS WATERS.-Free carbonic acid is
the characteristic and predominant element of these waters; it
is dissolved in the depths of the earth under a pressure much
greater than that of the atmosphere; hence a certain portion
of the gas is disengaged as soon as the water emerges from the
soil, giving rise to a greater or less effervescence. Gascous
waters are cold; their taste is piquant at the moment of emer-
gence, but often becomes saline or even alkaline after the dis-
engagement of the greater part of the carbonic acid gas. Nat-
ural gaseous waters never consist of a solution of carbonic
acid in pure water; they always contain a small quantity of
saline matters, principally traces of sodic, calcic, and magnesic
carbonates, and even traces of chlorides and sulphates. Such
is the composition of the celebrated Seltzer water and of Soultz-
matt water. The water of certain of the Saratoga springs
approximates in composition to Seltzer water.
ALKALINE WATERS.-These waters possess an alkaline re-
action, either immediately on their emergence or after the loss
of their free carbonic acid. This reaction may be due to an
alkaline silicate, but is generally referable to an alkaline car-
bonate. Sodium acid carbonate, NaHCO³, commonly called
bicarbonate of soda, exists in nearly all waters of this class,
together with an excess of carbonic acid. Vichy water con-
tains about 5 grammes of this salt per litre.
CHALYBEATE WATERS.-Nearly all waters contain traces
of iron in solution; chalybeate waters are such as contain
sufficient of that metal to give them an astringent taste and
special therapeutic properties. The iron may exist in three
conditions:
1. As ferrous carbonate held in solution by carbonic acid.
2. As ferrous crenate. Berzelius gave the names crenic
and apocrenic acids to two bodies which are related to peculiar
acids existing in the soil or humus, and which are known as
ulmic, humic, and geic acids. Ferrous crenate is soluble in
water; its constitution is not known.
3. As ferrous sulphate.
Consequently, chalybeate waters may be carbonated, cre-
nated, and sulphated.
The ferrous salts are never contained in these waters in large
proportions. Many ferruginous waters of undoubted efficacy
84
ELEMENTS OF MODERN CHEMISTRY.
do not contain more than 4 or 5 centigrammes per litre.
When exposed to the air they lose the greater part of their
carbonic acid, and ferrous carbonate is deposited, but this loses
its carbonic acid and is converted into brown ferric hydrate.
Such is the manner of formation and the nature of the ochrey
deposits always noticeable around ferruginous springs.
Chalybeate waters are widely diffused. Those of Spa and
Pyrmont, Belgium (carbonated), Bussang in the Vosges, and
Forges (crenated), and Passy, at Paris, are well known. Cele-
brated springs of this class exist at Bedford, Pennsylvania;
others are widely diffused throughout the United States.
SALINE WATERS.-This class includes a great number of
waters charged with various neutral salts, among which are the
chlorides, bromides, and iodides. The salts of sodium, mag-
nesium, and calcium are those more usually met with in these
waters. According to the predominating or peculiarly active
principle present, they are classified as chlorinated, sulphated,
and bromo-iodated waters. The Saratoga springs yield an
acidulo-saline water.
Chlorinated Saline Waters.-The chlorides generally found
in mineral waters are those of sodium, magnesium, and cal-
cium; the former is much the more abundant, and constitutes
one of the most common constituents of mineral waters. It
communicates to them a pure salty taste, free from bitterness.
A great number of saline springs serve for the extraction of
sodium chloride. After the evaporation of the water and the
deposition of the salt, a mother-liquor remains in which various
less abundant salts are concentrated, principally the alkaline
bromides and iodides.
Sea-water is a chlorinated water. It is well known that it
contains a notable proportion of sodium chloride (2.5 to 2.7
per cent.). The common salt is accompanied by the chlorides
of magnesium and potassium, and by a considerable quantity
of magnesium sulphate (0.6 to 0.7 per cent.).
The Dead Sea and the Great Salt Lake of Utah are the
most concentrated saline sources known. The water of the
latter contains 20 per cent. of sodium chloride.
Sulphated Saline Waters.-These are characterized by so-
dium, magnesium, or calcium sulphate. The springs of Carls-
bad, in Bohemia, contain a large proportion of sodium sulphate,
together with sodium bicarbonate and sodium chloride.
The purgative waters of Epsom, England, contain magne-
HYDROGEN DIOXIDE.
85
sium sulphate. The waters of Sedlitz, Saidschütz, and Pullna,
in Bohemia, contain magnesium sulphate and sodium sulphate.
Their taste is bitter. The Avon Spring, New York, is of this
class.
Bromo-iodated Waters.-Many mineral waters contain small
quantities of bromides and iodides, independently of the chlo-
rides which generally exist in much larger proportions. The
water of the Dead Sea, so rich in magnesium and sodium
chlorides, contain 0.43 per cent. of magnesium bromide. The
Iodine Spring at Saratoga contains a notable proportion of
alkaline iodides.
SULPHUR WATERS.-By this name are designated those
waters containing a soluble sulphide or sulphuretted hydro-
gen. They are either natural sulphur waters or accidental
sulphur waters. The first contain sodium sulphide; they are
generally warm, and contain but little solid matter. They all
disengage nitrogen on their emergence from the soil. They
contain a nitrogenized organic matter (baregine), and some-
times deposit a gelatinous precipitate (glairine).
Celebrated springs exist in the Pyrenees and at Bagnères-
de-Luchon. The sulphur springs of Sharon and Avon, in New
York, and the Red and White Sulphur Springs of Virginia
are well known.
Accidental sulphur waters are those which are formed upon
the spot by the reduction of sulphates, and particularly calcium-
sulphate, contained in the waters. This reduction is accom-
plished by the action of organic matters which impregnate the
soil, and of which the combustible elements, carbon and hydro-
gen, remove the oxygen of the sulphates. It is thus that the
sulphur water of Enghien is formed at the gates of Paris.
HYDROGEN DIOXIDE.
H202
This remarkable compound was discovered by Thenard in
1818. It is formed by the action of barium dioxide upon di-
lute hydrochloric acid. Barium dioxide, powdered and made
into a fine paste with water, is introduced by small portions.
into cold and dilute hydrochloric acid. It dissolves without
disengagement of gas, yielding barium chloride and hydrogen
dioxide.
BaO2 + 2HCI
BaCl2 + H202
Barium dioxide. Hydrochloric acid. Barium chloride. Hydrogen dioxide.
8
86
ELEMENTS OF MODERN CHEMISTRY.
The barium chloride is converted into sulphate, which pre-
cipitates, by the cautious addition of dilute sulphuric acid, and
at the same time hydrochloric acid is regenerated, so that an
additional quantity of barium dioxide may be added, and the
operation is several times repeated.
BaCl2 + H2SO¹
BaSO4 + 2HCI
Sulphuric acid. Barium sulphate.
The barium chloride finally remaining in solution is exactly
precipitated by a solution of silver sulphate, and the hydrogen
dioxide poured off and evaporated in vacuo.
Pure hydrogen dioxide is a syrupy, colorless, odorless liquid,
having a density of 1.452. It is very unstable, and readily
gives up half of its oxygen, being converted into water. This
decomposition takes place with a brisk effervescence when the
dioxide is heated towards 100°; it is also produced by con-
tact with a great number of bodies, some of which are them-
selves unaltered, some oxidized, and others even reduced.
Hence hydrogen dioxide enters into three classes of reactions.
1. If hydrogen dioxide, or more simply, water charged with
hydrogen dioxide, be poured into a test-tube containing man-
ganese dioxide, the hydrogen dioxide is instantly reduced with
effervescence into water and oxygen. The manganese dioxide
remains unchanged. Finely divided platinum, gold, silver, and
carbon act in the same manner.
2. Hydrogen dioxide energetically oxidizes arsenic and sele-
nium into arsenic and selenic acids. It converts lead sulphide
into sulphate.
PbS4H20²
Lead sulphide.
PbSO + 4H²O
Lead sulphate.
3. Potassium permanganate, KMnO¹, is a salt very rich in
oxygen; it dissolves in water, forming a solution having an
intense purple color. If hydrogen dioxide be added to it, it is
immediately reduced and decolorized. The oxygen from the
decomposition of the hydrogen dioxide is in this case added to
that from the reduction of the permanganate, and both are dis-
engaged in the free state.
If hydrogen dioxide be added to a solution of potassium di-
chromate, the latter assumes a deep blue color, but this rapidly
disappears, giving place to a green tint. At the same time an
evolution of oxygen takes place. In this case the reaction is
complex a portion of the hydrogen dioxide oxidizes the
HYDROGEN DIOXIDE.
87
chromic acid for an instant into blue perchromic acid, but the
latter is instantly reduced, with disengagement of oxygen, by
another portion of the hydrogen dioxide, which at the same
time loses half of its oxygen.
The oxygen gas liberated comes then at the same time from
the perchromic acid and the hydrogen dioxide, both of which
are supersaturated with oxygen, and which mutually reduce
each other. The perchromic acid formed may be removed.
from the action of the excess of hydrogen dioxide by imme-
diately agitating the liquid with ether: the latter dissolves the
acid and assumes a dark-blue color.
These experiments of reduction are of great interest, and
permit of but one explanation. The fact of the reciprocal
reduction of two bodies each supersaturated with oxygen can
only be explained by admitting that the oxygen of one body
possesses an affinity for that of the other, and that the oxygen
which is set free is formed by the union of two atoms, one from
the hydrogen dioxide, the other from the perchromic or per-
manganic acid. These two atoms unite to form a molecule of
oxygen 00. This would represent oxygen in the free state,
and occupy two volumes. It would be a true combination, and
we here encounter for the first time the important notion that
the atoms of certain elements are not isolated when in the free
state, but combined in pairs, each pair being held together by
chemical force. Free oxygen would then be oxygen oxide, a
combination of two atoms of oxygen, both together forming
a molecule, and occupying two volumes like the molecule of
water.
1 molecule of water
1 molecule of oxygen
H-Q-H=2 volumes.
0=0 2 volumes.
While the molecular structure of free oxygen or oxygen
oxide corresponds in a measure to that of hydrogen oxide or
water, there exists a peroxide of oxygen which corresponds in
a measure to hydrogen peroxide; it is ozone.
Hydrogen dioxide.
Oxygen dioxide (ozone).
H-0-0-H
88
ELEMENTS OF MODERN CHEMISTRY.
SULPHUR
Vapor density compared to air
Vapor density compared to hydrogen
Atomic weight S
2.22
32.
32.
Sulphur has been known from the greatest antiquity. In
certain volcanic countries it is found on the surface of the earth
in the native state. Sicily and Iceland contain large deposits
in the neighborhood of extinct volcanoes (solfatares). In order
to separate it from the earthy matters which accompany it, it
is subjected in Sicily to distillation in earthen pots (Fig. 32).

ENDEL
પાક
អា
A
BAN
獎
​FIG. 32.
These are arranged in two rows in furnaces, and communicate
by lateral tubulures with other pots which are placed outside
of the furnace, and in which the sulphur vapor is condensed.
Crude sulphur is thus obtained; it is still mixed with foreign
matters, from which it is separated by a new distillation. This
operation, which is called refining, is conducted in an apparatus
represented in Fig. 33.
A horizontal cast-iron cylinder, A, receives the melted sul-
phur from the vessel C, which is heated by the waste gases
from the furnace, and which serves as a reservoir. The sulphur
vapor enters a large masonry chamber, B, the floor of which is
SULPHUR.
89
slightly inclined in order that the condensed liquid sulphur may
flow towards a tap, H, which can be opened as is necessary. A
damper, R, that can be regulated by an articulated wire, per-
mits the closing and opening of the mouth of the cylinder.
The vault of the chamber is provided with a safety-valve, K,
which allows of the escape of the expanded air.
At the commencement of the operation, when the walls of
the chamber are cold, the sulphur condenses in the form of a
fine powder, which is known as flowers of sulphur. But when
the walls of the chamber become heated above the melting-
point of sulphur, the vapor condenses into a liquid, and on
opening the tap at H, it is drawn off into a vessel, E, from
which it is distributed into slightly conical or cylindrical moulds,
where it solidifies: Roll sulphur is thus obtained.

D
EFFETETLE
R
K
B
H
E-
FIG. 33.
Physical Properties. Sulphur is a lemon-yellow solid. It
is tasteless, odorless, and brittle; it is a non-conductor of heat
and electricity. A stick of sulphur pressed in the hand or
plunged into warm water produces a crackling sound, and
finally breaks into pieces; this is due to the unequal expan-
sion from the circumference to the centre of the non-conduct-
8%
90
ELEMENTS OF MODERN CHEMISTRY.
ing mass of sulphur, the crystalline particles of which are but
slightly held together by cohesion.
The density of sulphur is about 2.03. At 111.5° it melts
into a brownish-yellow, transparent liquid. If this liquid be
allowed to cool slowly until a crust forms upon the surface,
and the crust be pierced and the part still remaining liquid be
decanted, after removing the crust the interior of the vessel is
found covered with long, transparent, flexible needles of a
brownish-yellow color. These crystals are oblique-rhombic
prisms having a density of 1.98. This is not the only crystal-
line form assumed by sulphur. If a solution of sulphur in
carbon disulphide be allowed to evaporate spontaneously,
right-rhombic octahedral crystals are deposited having a den-
sity of 2.05. This form is also that of native crystallized
sulphur.
Sulphur crystallizes, then, in two distinct forms belonging
to two distinct crystalline systems. It is dimorphous. It is a
curious fact that the prisms formed by way of fusion do not
long retain their transparence and their flexibility. When aban-
doned for some time to ordinary temperatures, they become
opaque and brittle.
They are then found to be traversed
by a multitude of planes of cleavage, which are the faces of
microscopic octahedra similar to those obtained by way of
solution.
Reciprocally, the transparent octahedral crystals become
opaque when maintained for some time at a temperature of
111°; they are then transformed into a multitude of little
crystals of prismatic sulphur. It is seen that the two crystal-
line modifications of sulphur can be transformed into each
other. It is a curious instance of dimorphism.
Sulphur melted in a sealed tube will remain liquid for a
long time at temperatures below its ordinary point of solidifi-
cation; it is then said to be in a state of superfusion. When
it finally solidifies, it crystallizes in voluminous octahedra
having the form of crystallized native sulphur (Schützen-
berger).
There are other and amorphous modifications of sulphur.
Experiment.-If sulphur be melted in a flask, and the tem-
perature be gradually raised above its point of fusion, it as-
sumes a thick consistence and a dark color. At 220° it has a
brown-red color and is very thick. If while in this state it be
poured into cold water, it is converted into a soft, transparent,
SULPHUR.
91
brownish-yellow, and elastic mass. It has lost all crystalline
appearance; it has become amorphous, and is now soft sulphur.
When abandoned to itself for several days, it hardens, becomes
opaque, and reassumes the properties of ordinary sulphur.
This change takes place immediately if the soft sulphur be
heated to 90 or 95°; is then accompanied by a sensible disen-
gagement of heat (Regnault).
There are two modifications of soft sulphur. If it be treated
with carbon disulphide, a part of it is dissolved, and a residue
remains. The soluble part constitutes soluble soft sulphur;
the residue is insoluble soft sulphur (Ch. Sainte-Claire Deville).
In recently-sublimed flowers of sulphur the sulphur exists in
the amorphous condition.
Sulphur boils at 440°; its vapor is red. At 500° it has a
density of 6.654 (Dumas). Towards 1000° its density is only
about one-third as great. According to H. Deville and Troost,
the vapor density of sulphur, determined at 860° and reduced
by calculation to 0°, is 2.22. Compared to hydrogen, this
density is equal to 32, which is the normal density of sulphur
vapor, and gives its atomic weight. If 1 volume of hydrogen
weighs 1, 1 volume of sulphur vapor weighs 32; the latter
figure is therefore the atomic weight of sulphur.
But at a temperature a little above its point of ebullition
the vapor density of sulphur is 6.6, or three times greater than
at 860; this is accounted for by the fact that the sulphur
does not assume the true gaseous state below a temperature of
860°.
Sulphur is insoluble in water, but very slightly soluble in
alcohol, a little more soluble in ether and benzine. Its best
solvent is carbon disulphide.
Chemical Properties.-Sulphur possesses energetic affini-
ties. It combines directly with a great number of the other
elements. It is well known that it is combustible, burning
with a blue flame. Its combustion in air or oxygen produces
sulphurous oxide.
Sulphur combines directly with chlorine, bromine, iodine,
phosphorus, arsenic, and carbon, and with very many of the
metals. Iron and copper burn in the vapor of sulphur. The
sulphides thus formed generally possess the atomic constitution
of the corresponding oxides. Thus, the compound of sulphur
and carbon, carbon disulphide, is analogous to carbonic acid
gas. This analogy is maintained between a great number of
92
ELEMENTS OF MODERN CHEMISTRY.
oxygen and sulphur compounds, as will be seen by the follow-
ing examples:
H2O water.
H2S hydrogen sulphide.
KOH potassium hydrate.
KSH potassium sulphydrate.
CO2 carbon dioxide.
CS2 carbon disulphide.
K20 potassium monoxide.
K2S potassium monosulphide.
Bao barium monoxide.
BaS barium monosulphide.
K2CO3 potassium carbonate.
K2CS3 potassium sulphocarbonate.
SULPHYDRIC ACID, OR HYDROGEN SULPHIDE.
Density compared to air
Density compared to hydrogen.
Molecular weight H2S
•
1.192
17.
34.
This gas, known also as sulphuretted hydrogen, was discov-
ered by Meyer and Rouelle, and studied by Scheele, in 1777,
and by Berthollet.
Preparation. Hydrogen sulphide may be prepared by

B
FIG. 34.
gently heating antimony trisulphide in a flask with hydrochlo-
ric acid (Fig. 34). The gas is first passed through a wash-
HYDROGEN SULPHIDE.
93
bottle, B, containing a little water, and may then be collected
over the pneumatic trough.
The reaction which takes place is expressed by the following
equation:
Sb2S3 + 6HCI
2SbCl³ + 3H2S
Antimony trisulphide. Hydrochloric acid. Antimony trichloride.
The gas is generally prepared in the laboratory by the
reaction of dilute sulphuric acid with ferrous sulphide. The
operation requires no heat, and the reaction is as follows:
FeS + H2SO4
Ferrous sulphide. Sulphuric acid.
FeSO¹ + H2S
Ferrous sulphate.
As hydrogen sulphide is largely used in the laboratory, the
apparatus represented in Fig. 35 is convenient for its ready
production. It is composed of two large bottles, of which the

FIG. 35.
lower apertures are connected by a large caoutchouc tube. In
one of these bottles is placed a layer of broken glass or coke,
which is not attacked by sulphuric acid; upon this is placed
the ferrous sulphide in fragments. The neck of this bottle is
closed by a cork, through which passes a glass tube bearing a
stop-cock. The second bottle is nearly filled with dilute sul-
phuric acid. The stop-cock of the first bottle being opened,
the sulphuric acid enters until it attains the same level in both
bottles, and as soon as it reaches the ferrous sulphide the reac-
tion commences and hydrogen sulphide is disengaged. If the
94
ELEMENTS OF MODERN CHEMISTRY.
stop-cock be closed, the continued evolution of gas drives the
liquid back into the second bottle, until the disengagement of
gas ceases, which takes place as soon as the sulphuric acid no
longer touches the ferrous sulphide. The first bottle then
serves as a reservoir of hydrogen sulphide, containing the gas
under a pressure greater than that of the atmosphere, and
which can be increased by elevating the second bottle. In
order to obtain a current of the gas, it is sufficient to open the
stop-cock, and the flow can be regulated at will.
Physical Properties.-Hydrogen sulphide is a colorless gas.
It has a penetrating odor of putrid eggs. Under a pressure of
17 atmospheres, it condenses to a transparent, strongly refract-
ing liquid, having a density of about 0.91. At -85.5° this
liquid solidifies to a white crystalline mass (Faraday). Hydro-
gen sulphide is soluble in water. At 0°, one volume of water
dissolves 4.37 volumes; at 10°, 3.58 volumes; and at 20°,
2.90 volumes.
Composition.-2 volumes of hydrogen sulphide contain 2
volumes of hydrogen and 1 volume of sulphur vapor.
If a given volume of this gas be introduced into a bent tube
over mercury (Fig. 22), and a morsel of tin be then introduced
and heated for about twenty minutes, the hydrogen sulphide is
decomposed; the sulphur combines with the tin, and the hy-
drogen is set free. After cooling, the latter gas occupies a
volume exactly equal to that of the hydrogen sulphide at first
contained.
If, then, from the vapor density of hydrogen sulphide
we subtract the density of hydrogen
we find the number
•
which represents half the density of sulphur vapor.
17
1
16
It is hence concluded that one volume of hydrogen sulphide
contains half a volume of sulphur vapor to one volume of hy-
drogen.
It is also seen that hydrogen sulphide has exactly the same
chemical constitution as vapor of water.
H20= 2 volumes or one molecule of vapor of water.
H'S 2 volumes or one molecule of hydrogen sulphide.
The analogy between sulphur and oxygen is here manifested
in a striking manner. One atom of each of these elements,
requires two atoms of hydrogen. This is expressed by saying
that both oxygen and sulphur are diatomic elements.
HYDROGEN SULPHIDE.
95
Chemical Properties.-Hydrogen sulphide is combustible,
burning with a bluish flame. The products of its complete
combustion are water and sulphurous oxide. When mixed
with one and a half times its volume of oxygen, it explodes on
the application of a flame or the passage of an electric spark.
SO2 + H2O
H2S + 03
Two volumes. Three volumes. Two volumes. Two volumes.
When the supply of oxygen is insufficient, the combustion
is incomplete and sulphur is deposited.
In the presence of water, this oxidation takes place at ordi-
nary temperatures, occasioning a deposit of sulphur. In the
presence of moisture and porous matters it goes further, sul-
phuric acid being formed.
Hydrogen sulphide has a feeble acid reaction; it changes
blue litmus to a wine-red color. When it reacts with potassium
hydrate, water and potassium sulphydrate are formed.
H
H
}
K
S +
O
H
K
H
S +
H
H
}
Hydrogen sulphide. Potassium hydrate. Potassium sulphydrate.
Chlorine, bromine, and iodine decompose hydrogen sulphide,
combining with its hydrogen. When these bodies are dry, the
action is energetic, and the sulphur combines with the excess
of the element employed. If water be present, the sulphur
is set at liberty.
Bodies rich in oxygen readily decompose hydrogen sulphide.
Experiments.-1. If a few drops of the strongest nitric acid
be poured into a jar filled with hydrogen sulphide, the gas is
instantly inflamed. The nitric acid gives up oxygen, water is
formed, sulphur is set free, and abundant red fumes appear at
the same time.
2. If four volumes of hydrogen sulphide be mixed with two
volumes of sulphurous oxide over the mercury-trough, a deposit
of sulphur is at once formed.
2H2S + SO2
Hydrogen sulphide.
(4 volumes.)
2H2O + 3S
Sulphurous oxide. Water.
(2 volumes.)
Sulphur.
Hydrogen sulphide decomposes a great number of metallic
solutions, forming insoluble sulphides, which are precipitated.
Experiments.-1. If a solution of hydrogen sulphide be
added to a solution of blue vitriol or cupric sulphate, a brown
96
ELEMENTS OF MODERN CHEMISTRY.
precipitate of cupric sulphide is formed. The reaction is
expressed by the following equation :
CuSO4 + H2S
Cupric sulphate.
CuS+
H2SO⭑
Cupric sulphide. Sulphuric acid.
2. By an analogous reaction, a solution of plumbic acetate,
or a paper impregnated with that salt, is at once blackened by
the presence of hydrogen sulphide.
Hydrogen sulphide acts as a poison if inhaled in large
quantities or for any length of time.
HYDROGEN PERSULPHIDE.
This compound, discovered by Thenard, is analogous to hy-
drogen dioxide. It is prepared by pouring, drop by drop, a
solution of calcium disulphide into dilute hydrochloric acid.
CaS2 + 2HCl
CaCl2 + H2S2
Calcium disulphide. Hydrochloric acid. Calcium chloride. Hydrogen disulphide.
Hydrogen disulphide is formed and collects at the bottom
of the vessel in the form of a yellowish oil, having a disa-
greeable, irritating odor. Towards 60 or 70° it decomposes
rapidly into hydrogen sulphide and sulphur.
H2S2 H'S + S
This decomposition takes place slowly at ordinary tempera-
tures.
Hofmann attributes to this body the formula H2S³. He has
obtained a compound of this sulphide with an alkaloid, strych-
nine, the analysis of which has led him to conclude that there
are three atoms of sulphur in a molecule of the persulphide of
hydrogen.
OXYGEN ACIDS OF SULPHUR.
1. Sulphur forms three compounds with oxygen:
Sulphurous oxide SO
Sulphuric oxide SO³
Persulphuric oxide SO
sulphurous anhydride or
sulphur dioxide.
sulphuric anhydride or
sulphur trioxide.
recently discovered by
Berthelot.
SULPHUROUS OXIDE.
97
2. By combining with a molecule of water, these oxides are
converted into the corresponding acids.
SO2 + H2O=H'SO' sulphurous acid.
SO³ + H2OH'SO' sulphuric acid.
·
3. There are two other important acids of sulphur, hypo-
sulphurous and hyposulphuric acids. The former may be con-
sidered as sulpho-sulphuric acid, that is, sulphuric acid in
which 1 atom of oxygen is replaced by an atom of sulphur.
H2SO¹ sulphuric acid.
H2(SO³)S sulpho-sulphuric or hyposulphurous acid.
Hyposulphuric acid may be considered as resulting from the
addition of sulphurous oxide to sulphuric acid.
SO² + H2SO₁ = H2S2O6 hyposulphuric acid.
4. These are not the only known sulphur acids.
Hyposulphuric acid, which is called also dithionic acid, is
the first of a series of acids, each of which contains 2 atoms of
hydrogen and 6 atoms of oxygen, the number of sulphur atoms
regularly increasing. This series is called the thionic series.
The following is the nomenclature and composition of the
acids:
H2S2O dithionic, hyposulphuric acid.
H2SO trithionic acid.
H2S4O6 tetrathionic acid.
H2S50° pentathionic acid.
5. Schützenberger has recently made known a new sulphur
acid, which he has named hydrosulphurous acid, and which is
formed by the action of zinc upon sulphurous acid, as will be
described farther on. The composition of this acid is repre-
sented by the formula
H2SO².
There is an interesting relation between this acid and sul-
phurous and sulphuric acids.
H'SO2 hydrosulphurous acid.
H'SO³ sulphurous acid (not yet isolated).
H2SO¹ sulphuric acid.
SULPHUROUS OXIDE.
Density compared to air
Density compared to hydrogen
Molecular weight S02
2.234
32.
64.
F
9
98
ELEMENTS OF MODERN CHEMISTRY.
Sulphurous oxide or sulphurous acid gas may be prepared
by decomposing sulphuric acid with copper. The metal in
small clippings and the acid are introduced into a flask fitted

FIG. 36.
with a delivery-tube (Fig. 36); heat is applied and the gas
collected over the mercury-trough. The reaction which takes
place is expressed by the following equation:
Cu + 2H2SO4
CuSO¹ + 2H²O + SO²
Copper. Sulphuric acid. Cupric sulphate.
A solution of sulphurous acid in water is often needed in
the laboratory. It may be conveniently prepared by reducing
sulphuric acid by charcoal; the products of the reaction are
water, and sulphurous and carbonic acid gases.
2H2SO¹ + C
Sulphuric acid.
2H2O + 2SO² + CO2
Carbon dioxide.
The mixed gas is passed through a series of bottles contain-
ing water, which dissolves the sulphurous oxide, but takes up
only an insignificant quantity of the carbon dioxide.
Physical Properties.-Sulphur dioxide is a colorless gas
having a pungent, suffocating odor. It is readily liquefied by
being led into a vessel surrounded by a mixture of ice and salt.
It condenses at ordinary temperatures, under a pressure of
about two atmospheres. The liquid has a density of 1.45; it
boils at -10°, and produces great cold by its evaporation; on
this account it is used for the manufacture of ice, and in other
cases where intense cold is required. -73° may be obtained
SULPIIUROUS OXIDE.
99
by the evaporation of liquid sulphurous acid aided by double-
acting pumps (Raoul Pictet).
Water at 0° dissolves 79.9 times its volume of sulphurous
oxide, and only 39.4 volumes at 20°.
Experiments.-1. If a small quantity of mercury contained
in a porcelain capsule be covered with a deep layer of liquid
sulphurous oxide, and the evaporation of the latter be favored
by directing a rapid current of air over its surface, the mercury
is frozen into a solid button.
2. When liquid sulphurous acid is poured into not too great
a quantity of water, a part of it is dissolved, but the excess
absorbs heat from the mass of liquid, volatilizes suddenly, and
the water is frozen.
Chemical Properties.-Sulphurous oxide is not decom-
posed by heat. It is incombustible, and extinguishes burning
bodies.
If a
Its most striking property is its affinity for oxygen.
mixture of two volumes of sulphurous oxide and one volume
of oxygen be passed through a tube containing slightly heated
spongy platinum, the two gases combine, forming sulphuric
oxide (Kuhlmann).
A solution of sulphurous oxide in water slowly absorbs oxy-
gen, and is converted into sulphuric acid. It
It may be admitted
that the aqueous solution contains the veritable sulphurous acid.
H2SO3 + 0
Sulphurous acid.
H2SO
Sulphuric acid.
Sulphurous acid reduces a great number of oxidized bodies.
At ordinary temperatures it takes the oxygen from iodic acid,
setting free the iodine; but the latter disappears on the addi-
tion of an excess of sulphurous acid, sulphuric and hydriodic
acids being formed.
H2SO3 + H2O + I²
H2SO¹ + 2HI
It decolorizes the purple solution of potassium permanganate,
forming manganese sulphate and potassium sulphate. It con-
verts arsenic acid into arsenious acid. It combines directly
with lead dioxide, forming lead sulphate.
PbO2 + SO²
Lead dioxide.
PbSO¹
Lead sulphate.
Chlorine will unite directly with sulphurous oxide. If a
mixture of equal volumes of chlorine and sulphurous oxide be
100
ELEMENTS OF MODERN CHEMISTRY.
exposed to sunlight, the two gases combine, forming a liquid
having a suffocating odor. It is sulphuryl chloride. Its den-
sity is 1.66, and its boiling-point is 77°. It may be regarded
as sulphur trioxide in which one atom of oxygen is replaced
by two atoms of chlorine.
SO³ = (SO²)"O sulphuryl oxide or sulphuric oxide.
SO2C12
(SO2)"Cl sulphuryl chloride.
In these reactions in which the sulphurous oxide combines
directly with either one atom of oxygen or two atoms of chlorine,
it plays the part of an element; it is a compound radical, and
this radical is diatomic, because it unites with two atoms of the
monatomic element chlorine, or with one atom of the diatomic
element oxygen, which is equivalent to two atoms of chlorine.
In the formulæ given, the diatomicity is expressed by the
accents ".
Sulphurous acid bleaches various vegetable and animal mat-
ters. A bouquet of violets or a rose is bleached in a few minutes
by a solution of sulphurous oxide.
Sulphurous oxide is employed in the arts to bleach wool.
HYDRO-SULPHUROUS ACID.
H2SO²
While sulphurous acid reduces a number of bodies, it is in
its turn reduced by the action of zinc upon its aqueous solution.
A yellow liquid is thus obtained which energetically bleaches
indigo and litmus solutions (Schönbein). Schützenberger has
shown that the liquid gifted with these properties contains the
zinc salt of a new acid, which he has named hydrosulphurous.
This acid is formed by the combination of hydrogen with sul-
phurous oxide. The reaction is expressed by the following
equations:
H2SO3 + Zn
Sulphurous acid.
Zinc.
SO2 + H2
Sulphurous oxide.
ZnSO³ + H2
Zinc sulphite.
H2SO2
Hydrosulphurous acid.
When this liquid is treated with very dilute sulphuric acid,
it gives a liquor of a dark orange-yellow color, having ener-
getic bleaching powers. It then contains hydrosulphurous
acid. It soon becomes clouded and deposits sulphur. This
SULPHUR TRIOXIDE, OR SULPHURIC OXIDE.
101
acid is not stable, but its acid sodium salt is more so; the latter
has the composition NaHSO". It readily absorbs oxygen from
the air, being converted into sodium acid sulphite.
NaHSO² +- O
NaHSO³
This oxidation is also brought about by the presence of cer-
tain metallic salts, such as those of copper, mercury, and lead.
In this case the metal is reduced and precipitated, and the
hydrosulphite is decomposed, yielding sulphurous oxide.
NaHSO² + CuSO¹
NaHSO¹ + SO² + Cu
Sodium hydrosulphite. Cupric sulphate. Sodium acid sulphate.
Sodium acid hydrosulphite may be obtained by the electro-
lysis of a solution of sodium acid sulphite. In this case the
hydrogen, which would otherwise be disengaged at the negative
pole, accomplishes the reduction.
NaHSO³ + H² = NaHSO² + H²O
SULPHUR TRIOXIDE, OR SULPHURIC OXIDE.
(SULPHURIC ANHYDRIDE.)
Vapor density compared to hydrogen
Molecular weight S03
•
40.
80.
Sulphur trioxide is formed by the union of oxygen with sul-
phurous oxide in the presence of finely-divided platinum.
It is prepared by gently heating fuming sulphuric acid in a
retort; vapors are given off which, when condensed in a re-
ceiver surrounded by a freezing mixture, solidify into a white
mass, having a fibrous appearance and a silky lustre.
Sulphur trioxide boils at a temperature between 30 and 35°.
At ordinary temperatures it produces white fumes in the air
by condensing the atmospheric moisture. Its most striking
property is its affinity for water; when thrown into that liquid,
it becomes hydrated with such energy that a portion of the
water is suddenly vaporized, and a hissing noise is produced
similar to that heard on plunging a red-hot iron into water.
Sulphuric acid is formed by the reaction.
SO³ + H2O
H2SO
9***
102
ELEMENTS OF MODERN CHEMISTRY.
SULPHURIC ACID.
Molecular weight H2SO4
98.
This acid, which has been known for centuries, was formerly
obtained by the distillation of ferrous sulphate. Large quan-
tities of it are now consumed in the arts, and it is manufac-
tured in extensive apparatus known as leaden chambers. Sul-
phurous oxide is conducted into these chambers, where it
meets with nitric acid, by which it is oxidized.
SO² + 2HNO³
Nitric acid.
H2SO4 + 2NO2
Nitrogen peroxide.
The products of the first reaction are sulphuric acid and
nitrogen peroxide (red vapors); but the latter is decomposed
by steam, which is injected into the chamber; nitric acid is
regenerated and nitrogen dioxide is formed.
3NO² + H2O
Nitrogen peroxide.
2HNO3 + NO
Nitrogen dioxide.
But the nitrogen dioxide is not lost; it combines with the
oxygen of the air contained in the chamber, and is reconverted
into nitrogen peroxide.
NO+0= NO²
The latter is again decomposed into nitric acid and nitrogen
dioxide by the action of water, and the sulphurous oxide which
continually arrives in the chamber always encounters nitric
acid, by which it is converted into sulphuric acid. It is a
continuous operation, which theoretically leaves no residue,
and permits of the conversion of an indefinite amount of sul-
phurous oxide into sulphuric acid.
It is really the oxygen of the air, continually absorbed and
given up by the nitrogen dioxide, which effects the oxidation
of the sulphurous oxide; the nitric acid is the direct agent,
and the nitrogen dioxide is intermediate, for it is the vehicle
for the transfer of the oxygen.
Fig. 37 represents a section of a series of leaden chambers
for the manufacture of sulphuric acid.
Sulphur is burned in two furnaces, AA, and the heat gen-
erated is employed to boil the water contained in the boilers
SULPHURIC ACID.
103

FIG. 37.
IL
104
ELEMENTS OF MODERN CHEMISTRY.
above the flame, the steam being distributed to the chambers
by the pipes c d. The sulphurous oxide, together with a
great excess of air, passes through the pipes BB into a leaden
drum, C. A thin layer of sulphuric acid charged with nitrous
products trickles over the inclined shelves in the drum. The
gases pass first into the chamber C, then into D, where they
meet with nitric acid, which falls in thin layers over a double
cascade, EE, in such a manner as to present a large surface for
the action of the sulphurous oxide. The sulphuric acid which
is formed in this chamber is charged with nitrous products; it
is therefore allowed to flow by the inclined tube F into the
chamber C, where it encounters an excess of sulphurous oxide,
and which is called the denitrifier. The sulphurous oxide, the
excess of air, and the nitrogen peroxide pass from D into the
large chamber HH, into which steam is projected by several
jets. Here the larger portion of the sulphuric acid is pro-
duced, and the reaction is completed in another chamber.
the engraving the last two chambers are not fully represented.
The gases from the last chamber enter a refrigerator, in which
the condensation takes place; they are lastly conducted into a
leaden column, R, filled with coke which is kept saturated
with sulphuric acid by a thin stream from the reservoir O.
This acid completely absorbs the nitrogen dioxide, and descends.
by the tube ba into the reservoir i, situated near the furnace.
As soon as this reservoir is full, the stop-cock r is closed, and
' is opened; the pressure of the steam then forces the acid
up into the reservoir g, which feeds the first drum. The gas
which escapes from the last column, which is known as Gay-
Lussac's column, consists of nitrogen charged with an insig-
nificant quantity of nitrous products.
In
The acid which is drawn from the chambers is not suffi-
ciently concentrated, having a density of only about 1.5. It
is first evaporated in leaden vessels until it becomes strong
enough to act upon the lead, and the concentration is then fin-
ished in large platinum retorts. The excess of water is thus
driven out. The concentrated acid possesses a density of
1.842.
In many manufactories pyrites is burned instead of sulphur.
Sulphurous oxide is produced, and a residue of ferric oxide.
remains.
Purification of Sulphuric Acid.-The sulphuric acid of
commerce contains impurities. It holds in solution a small
SULPHURIC ACID.
105
quantity of lead sulphate, formed in the evaporating basins; it
is often charged with nitrous products, and sometimes with ar-
senic acid, when the sulphurous oxide employed in its prepa-
ration has been obtained by the combustion of arsenical pyrites.
It may be freed from these impurities by distillation. The
nitrous products are first disengaged, and are found in the first
portions of the distillate, which must be rejected. Pure sul-
phuric acid then passes; the lead sulphate and arsenic acid
remain in the retort with the last portions of the acid, which
must not be distilled.
The operation may be conducted in a glass retort connected
with a cooled receiver. The retort should be heated laterally
by an annular flame so that explosive evolution of vapor may
be avoided, and it is well to introduce some platinum wires with
the acid, and to cover the retort with a sheet-iron hood.
Constitution of Sulphuric Acid. Since oxygen combines
directly with sulphurous oxide to form sulphuric oxide, the
latter may be regarded as sulphuryl oxide, SÕ²O.
Sulphuric acid is the hydrate of this oxide.
SO³ + H2O H2SO4
The following experiment indicates the relations which exist
between the elements composing this hydrate.
If sulphuryl chloride be poured into water, it disappears,
sulphuric acid and hydrochloric acid being formed.
SO2
{
Cl
HOH
Cl
+
SO2
HOH
(OH
2
OH + 2HCI
Sulphuryl
chloride.
2 molecules
of water.
Sulphuric
acid.
2 molecules
hydrochloric acid.
Sulphuric acid is thus formed by the decomposition of 2
molecules of water, of which 2 atoms of hydrogen have been
removed by 2 atoms of chlorine, and replaced by the group
SO². It may then be truly said that sulphuric acid is derived
from two molecules of water by the substitution of the diatomic
radical (SO²)" for two monatomic atoms of hydrogen.
H.OH
H.OH
(SO²)"
SOH
гон
2 molecules of water.
Sulphuric acid.
If the composition of sulphuric acid be compared to that
of sulphuryl chloride, from which it may be formed, it will be
E*
106
ELEMENTS OF MODERN CHEMISTRY,
seen that both compounds contain the same nucleus or radical
SO³, and that instead of the two atoms of chlorine of the
chloride, the acid contains two groups OH. The group OH
is a residue, as it were, which represents a molecule of water
minus one atom of hydrogen, and which is called hydroxyl.
It is a monatomic group, and sulphuric acid is formed by the
saturation of the affinity of the diatomic radical sulphuryl by
two monatomic groups hydroxyl, which replace the two atoms
of chlorine of sulphuryl chloride. Williamson has described
an intermediate compound in which the radical sulphuryl is
combined with one atom of chlorine and one OH group.
SO2
{
CI
Cl
SO OH
{
La
SCI
SO2
{
JOH
OH
Sulphuryl chloride. Sulphuryl chlorohydrate.
Sulphuric acid.
The sulphur in sulphuric acid is hexatomic.
HO-S-OH
Physical Properties.-Sulphuric acid is a colorless oily
liquid; its density at 12° is 1.842 (Marignac). Its boiling-point
is 325°, and it solidifies at -34°. If it be crystallized several
times at a low temperature, and the part remaining liquid be
decanted off each time, the melting-point is gradually raised to
+10.5°, where it remains stationary. According to Marignac,
the acid which solidifies and fuses at +10.5° constitutes the
true monohydrated acid, H2SO¹. At a temperature about 40°
it emits some fumes, and between this point and 290° it disen-
gages a small quantity of vapor of sulphuric oxide. At 290°
it begins to boil, but its boiling-point soon rises to 338°, where
it remains. Such are, according to Marignac, the properties of
monohydrated sulphuric acid. According to this chemist, the
acid purified by simple distillation, and boiling at 325°, still
contains a small amount of water.
Chemical Properties.-When exposed to a red heat, sul-
phuric acid decomposes into sulphurous oxide, oxygen and
water.
H2SO¹ SO² + 0 + H2O
Many bodies having an affinity for oxygen reduce sulphuric
SULPHURIC ACID.
107
acid by the aid of heat. Thus sulphur effects the reduction,
being at the same time oxidized to sulphurous oxide.
2H2SO4 + S 3S0² + 2H2O
We have already studied the action of charcoal and copper
upon sulphuric acid when boiled with that liquid, and we have
seen that zinc and iron decompose the dilute acid with evolu-
tion of hydrogen and formation of a sulphate.
When four
Sulphuric acid has a strong affinity for water.
parts of sulphuric acid are quickly mixed with one part of
water, the temperature rises to above 100°. If the experiment
be made with large quantities, it is not without danger, and re-
quires prudence lest part of the acid be projected from the vessel.
Experiments. If four parts of sulphuric acid be quickly
added to one part of snow, the latter is immediately liquefied
and a notable elevation of temperature takes place; for the
energy of the combination of the sulphuric acid with the water
is so great that the heat produced by the union is greater than
that consumed in the liquefaction of the ice.
But if four parts of snow be mixed with one part of sul-
phuric acid, the result is the reverse; there is a lowering of
temperature.
The affinity of sulphuric acid for water is manifested in a
number of reactions. In the following it is sufficiently power-
ful to cause the formation of the water it requires :
If a morsel of sugar be moistened with sulphuric acid, it
becomes blackened and carbonized in a few minutes. The sugar
contains no water already formed, but independently of carbon
it contains hydrogen and oxygen in the proportions necessary
to form water, so that the latter compound is produced by the
influence of the sulphuric acid, and a carbonaceous matter
remains.
This water which is absorbed by sulphuric acid with so much
energy, combines with the acid in a manner analogous to that
in which water of crystallization combines with certain salts.
Indeed, if sulphuric acid to which 18.3 per cent. of water has
been added be exposed to a temperature of 0°, large prismatic
crystals are formed, which remain solid even at a temperature
of +7° or +8°. The composition of these crystals is ex-
pressed by the formula H2SO¹,H2O. They constitute a dihy-
drated acid, for they result from the union of two molecules
of water with one molecule of sulphuric oxide.
108
ELEMENTS OF MODERN CHEMISTRY.
Sulphuric acid is a dibasic acid; that is, it contains two atoms
of hydrogen that are replaceable by an equivalent quantity of
metal. This substitution takes place when the acid is treated
with a hydrate, such as potassium hydrate, or with an oxide,
such as lead oxide.
H²SO* + 2KOH
Potassium hydrate.
H2SO4 + PbO
K²SO¹ + 2H2O
Potassium sulphate.
PbSO + H2O
Lead oxide. Lead sulphate.
When saturated with potassium hydrate, the sulphuric acid
is converted into potassium sulphate, and, in the salt, two atoms
of potassium replace the two atoms of hydrogen of the acid.
In the case of the lead oxide, on the contrary, the reaction,
which is only a double decomposition, takes place so that a
single atom of lead replaces the two atoms of hydrogen. The
metal lead is then said to be diatomic; that is, one atom of
lead is capable of replacing two atoms of a monatomic element
such as hydrogen, and one atom of lead is equivalent to two
atoms of potassium.
Sulphuric acid may be detected by the following reactions,
which are also applicable to the soluble sulphates.
In solutions containing sulphuric acid or a sulphate, barium
salts produce a white pulverulent precipitate, which is insolu-
ble in either cold or hot nitric acid; this precipitate is barium
sulphate. When mixed with an excess of charcoal and heated
to whiteness, it is converted into barium sulphide.
BaSO¹ + 40
Barium sulphate.
4CO
BaS
Carbon monoxide. Barium sulphide.
The sulphide of barium disengages hydrogen sulphide when
it is moistened with hydrochloric acid; this gas may be recog-
nized by its odor and by its blackening a paper impregnated
with lead acetate.
FUMING SULPHURIC ACID.
Fuming sulphuric acid, or Nordhausen sulphuric acid, as it
was formerly called, can be regarded as a combination of sul-
phuric acid and sulphuric oxide.
OH
SO2<
H2SO¹ + SO³ H2S2O7
O
SO²<
OH
HYPOSULPHUROUS ACID.
109
It is a light-brown, oily liquid. At 0° it solidifies into a leafy
mass. It gives off white fumes in the air. When heated, it
decomposes into sulphuric oxide and sulphuric acid. It is ob-
tained in the arts by the distillation of ferrous sulphate that has
been previously transformed into ferric subsulphate by roasting.
This subsulphate is calcined in stoneware retorts; it gives
off sulphuric oxide when it is perfectly dry, but as it is difficult
to entirely free it from water of crystallization, the vapor of
sulphuric oxide is mixed with that of sulphuric acid, and the
mixed vapors are condensed in cooled receivers. The residue
of the distillation is ferric oxide, Fe²O³.
HYPOSULPHUROUS OR SULPHO-SULPHURIC
ACID.
H2S (SO³)
This acid is not known in the free state. When sodium
hyposulphite is treated with dilute sulphuric acid, the hypo-
sulphurous acid set free is at once decomposed into sulphurous
acid and sulphur.
Na2S2O3 + H2SO¹
Sodium hyposulphite.
Na2SO4 + H2SO³ + S
Sodium sulphate.
Sodium hyposulphite is formed when sulphur is boiled with
a solution of sodium sulphite.
Na2SO3+ S
Sodium sulphite.
Na2S (SO³)
Sodium hyposulphite.
It is a very soluble salt, forming voluminous crystals.
HYPOSULPHURIC ACID.
H2S206
If fuming sulphuric acid represent a combination of sul-
phuric acid and sulphuric oxide, hyposulphuric acid can be
regarded as resulting from the union of sulphuric acid with
sulphurous oxide.
SO³.H SO' fuming sulphuric acid.
SOH SO hyposulphuric acid.
Preparation.-Hyposulphuric acid is prepared by passing
sulphurous oxide into water in which manganese dioxide is sus-
pended.
2SO² + MnO2
MnS206
Manganese dioxide. Manganese hyposulphate.
10
110
ELEMENTS OF MODERN CHEMISTRY.
Manganese hyposulphate is thus formed, and this is con-
verted into barium hyposulphate by a double decomposition
with barium sulphide. The liquid is separated from the man-
ganese sulphide by filtration, and exactly decomposed with
dilute sulphuric acid. Barium sulphate is precipitated, and the
hyposulphuric acid remains in solution. The liquid is then
concentrated in vacuo.
Properties. Hyposulphuric acid is a very acid, syrupy
liquid, having a density of 1.347. It is not stable; when
boiled it decomposes into sulphuric acid and sulphurous oxide.
PERSULPHURIC OXIDE.
S207
This body has been very recently discovered by Berthelot,
who obtained it in the pure state by the action of silent elec-
tric discharges of high tension upon a mixture of equal vol-
umes of sulphurous oxide and oxygen, both perfectly dry.
Persulphuric oxide is formed, and there remains a residue of
oxygen.
S201
4 vol. sulphurous oxide.
04
+
4 vol. oxygen.
S207 +
Persulphuric oxide.
Oxygen.
When pure it is solid at ordinary temperatures, crystallizing
sometimes in grains, sometimes in thin and flexible transparent
needles. Sometimes it remains liquid.
It is not stable, and decomposes spontaneously in about two
weeks. When heated, it decomposes rapidly into sulphuric
oxide and oxygen.
S207
Persulphuric oxide.
2SO3
Sulphuric oxide.
+
Water dissolves it with production of dense fumes and a
brisk effervescence due to the disengagement of oxygen. The
liquid then contains sulphuric acid. At the same time a small
quantity of persulphuric acid, H2S2O8, or HSO*, is formed,
which soon decomposes into sulphuric acid and oxygen.
This persulphuric acid, which is very unstable, would be
analogous to permanganic acid; its formation is expressed by
the following equation:
S²07 + H2O
2HSO¹
SELENIUM AND TELLURIUM.
111
According to Berthelot, persulphuric acid is formed by the
electrolysis of concentrated solutions of sulphuric acid. It
would also be formed by the careful addition of a solution
of hydrogen dioxide to sulphuric acid slightly diluted with
water.
2H²SO¹ + 0 = H²0 + 2HSO¹
It is by no means certain that the formula HSO¹ represents
the composition of a molecule of persulphuric acid. It is pos-
sible that this formula must be doubled as indicated above.
At present this point cannot be decided.
SELENIUM AND TELLURIUM.
These two rare elements present a great analogy to sulphur.
Selenium was discovered by Berzelius in certain Swedish
pyrites. Like sulphur, selenium has two allotropic forms, one
crystalline, the other vitreous and amorphous. The crystalline
variety begins to melt above 217°, but liquefies only at 250°
(Regnault); after rapid cooling it solidifies into a dark-brown
mass. Its density is 4.8 when crystallized, and 4.3 when vit-
reous. When heated in the air to a temperature above its
melting-point it takes fire and burns with a blue flame, being
converted into selenious oxide, SeO². When sulphurous acid
is added to a solution of selenious oxide the latter is reduced,
sulphuric acid is formed, and the selenium is precipitated in
the form of brown-red flakes. Its compound with hydrogen
is a colorless gas having a fetid and irritating odor.
Tellurium is still more rare than selenium; it occurs com-
bined with gold and other metals in certain minerals of Tran-
sylvania and Hungary, and also in the Rocky Mountain gold
region in the United States. It has the external appearance
and the lustre of a metal. Its color is silvery-white; its den-
sity 6.25.
It melts at about 500°, and can be volatilized at a
white heat in a current of hydrogen. It has a great tendency
to crystallize. When heated in the air it burns with a green-
ish-blue flame, forming tellurious oxide, TeO'. Its compound
with hydrogen is a gas having an odor analogous to that of
hydrogen sulphide.
The following table shows the analogy between the principal
compounds of sulphur, selenium, and tellurium:
112
ELEMENTS OF MODERN CHEMISTRY.
H2S
H2Se
H2Te
Hydrogen sulphide.
Hydrogen selenide.
Hydrogen telluride.
SeO²
TeO2
Tellurious oxide.
TeO3
SO2
Sulphurous oxide.
SO³
Sulphuric oxide.
[H2SO³]
Sulphurous acid.
H2SO¹
Sulphuric acid.
Selenious oxide.
[SeO³]
Selenic oxide.
H2SeO3
Selenious acid.
H²SeO¹
Selenic acid.
Telluric oxide.
H2TeО³
Tellurious acid.
H2TeO¹
Telluric acid.
CHLORINE.
Density compared to air
Density compared to hydrogen
Atomic weight Cl .
2.44
35.5
35.5
Chlorine was discovered by Scheele in 1774, and was first
recognized as an element by Gay-Lussac and Thenard in 1809,
and by Sir Humphry Davy in 1810.
Preparation. One part of manganese dioxide in coarse.
powder and six parts of common hydrochloric acid are intro-

FIG. 38.
duced into a flask fitted with a safety-tube and delivery-tube
(Fig. 38). The reaction begins in the cold; chlorine gas is
CHLORINE.
113
As soon as
disengaged, and may be collected over salt water.
the disengagement of gas diminishes, it may be re-established
by the application of a gentle heat.
It is more convenient to collect the gas by dry displacement,
and it may be obtained pure and dry by being conducted
through a wash-bottle containing a small quantity of water, and
a tube containing calcium chloride, as represented in the figure.
It is then passed, by means of a tube bent at a right angle,
into a dry jar. The chlorine being heavier than the air, col-
lects at the bottom of the jar and gradually drives out the air,
and the uniform greenish color of the whole of the gas in the
jar indicates when the latter is completely filled.
If it be desired to prepare a solution of chlorine in water,
the gas may be passed through a series of Wolff's bottles con-

FIG. 39.
taining water, the contents of the first bottle being rejected,
serving merely to wash the gas (Fig. 39).
The reaction which takes place in the preparation of chlo-
rine is a double decomposition between the manganese dioxide
and the hydrochloric acid. Water and manganese chloride
are formed, and chlorine is set free.
MnO2
+ 4HC1 2H2O + MnCl² + `Cl²
Manganese dioxide. Hydrochloric acid.
Manganese chloride.
Physical Properties.-Chlorine is a greenish-yellow gas
10*
114
ELEMENTS OF MODERN CHEMISTRY.
having a strong and suffocating odor. A litre of this gas
weighs 3.16 gr. It may be liquefied at 15° by a pressure of
four atmospheres. A small quantity of the liquid may easily
be prepared in the following manner:
The
Some crystals of chlorine hydrate are introduced into a tube
of thick glass closed at one end and bent in the middle; the
other end is then hermetically
sealed at the blast-lamp.
branch containing the crystals is
then heated in a water-bath, while
the other branch is cooled in a
freezing mixture (Fig. 40). The
hydrate of chlorine breaks up
into water and chlorine, and the
greater part of the latter is disen-
gaged, and condenses by its own
pressure into a deep-yellow liquid,
which collects in the cooler limb
of the tube (Faraday).

FIG. 40.
Chemical Properties.-One volume of water at 8° dissolves
3 volumes of chlorine; at 17°, 2.42 volumes. The saturated
solution has a yellow color. When it is exposed to a tempera-
ture of 0°, it deposits crystals containing 27.7 per cent. of
chlorine, and 72.3 per cent. of water, and constituting a hydrate
of chlorine corresponding to the formula Cl² + 10H2O (Fara-
day).
Chlorine possesses powerful affinities. It unites directly
with the greater number of the other elements, and the com-
bination frequently takes place with such energy that luminous
heat is produced.
Experiments. If powdered antimony or arsenic be sprinkled
into a jar containing dry chlorine, each particle of the black
powder burns with a bright spark as soon as it enters the atmos-
phere of chlorine, producing thick, white fumes of antimony
or arsenic chloride as the case may be.
If a morsel of phosphorus, contained in a deflagrating spoon,
be plunged into a jar of chlorine, the phosphorus melts and
inflames spontaneously, and the sides of the jar become covered
with a yellow, crystalline deposit of phosphorus pentachloride,
PC15.
But the affinity of chlorine is most strikingly manifested by
its action on hydrogen and hydrogen compounds.
CHLORINE.
115
When a lighted taper is applied to a mixture of equal vol-
umes of chlorine and hydrogen, the two gases unite instantly
and explosively. Such a mixture will also explode violently
on being exposed to direct sunlight; the rays of the sun may
even be replaced by the flame of magnesium or that of carbon
disulphide.
So great is the affinity of chlorine for hydrogen that it de-
composes all hydrogen compounds, except hydrochloric and
hydrofluoric acids. When it is dissolved in water, it slowly
decomposes that liquid under the influence of sunlight, com-
bining with the hydrogen and setting the oxygen at liberty.
If a tube filled with an aqueous solution of chlorine be
inverted over the pneumatic trough and exposed to direct sun-
light, small bubbles of gas will be seen to rise through the liquid
and collect at the top of the tube. This is the oxygen result-
ing from the decomposition of the water.
At a red heat, the vapor of water is rapidly decomposed by
chlorine; hydrogen sulphide gives up its hydrogen to chlorine
at ordinary temperatures.
All organic substances contain hydrogen; they are therefore
generally modified, and often destroyed by the action of chlorine.
Coloring matters of organic origin are bleached.
Experiment. If a solution of chlorine be added to a solu-
tion of litmus, sulphate of indigo, or ink, the intense colors
peculiar to these substances disappear, giving place to a pale
yellow or brown tint. This effect is due to the more or less
profound decomposition which these coloring matters undergo
by reason of the removal of a certain portion of their hydro-
gen in the form of hydrochloric acid.
This bleaching property of chlorine is of great service in the
arts.
A wax taper will burn in chlorine gas with a red, smoky
flame. The hydrogen of the wax combines with the chlorine,
while the carbon is set free as smoke. A piece of paper satu-
rated with oil of turpentine takes fire spontaneously when
introduced into a jar of chlorine, producing a dense cloud of
smoke; the turpentine contains only carbon and hydrogen the
latter is attacked by the chlorine, the former being set free.
Chlorine is also an efficacious disinfectant. It decomposes
hydrogen sulphide. It destroys odorous matters of organic
origin, the effluvia resulting from putrid fermentation, and
the miasms which are sometimes diffused in the air. It
116
ELEMENTS OF MODERN CHEMISTRY.
is employed to disinfect privys, etc., and to purify the air in
certain epidemics.
The bleaching properties and disinfecting properties of
chlorine are due to the same cause, its powerful affinity for
hydrogen.
HYDROCHLORIC ACID.
Density compared to air.
Density compared to hydrogen
Molecular weight HCI
1.247
18.
36.5
Hydrochloric acid exists among the gaseous products disen-
gaged by volcanoes.

R
Før henna 10% soAT
donne, a mu, Halbert
い
​FIG. 41.
Preparation. Fragments of fused common salt are intro-
duced into a flask fitted with a safety-tube and delivery-tube,
like that for the preparation of chlorine, and concentrated sul-
phuric acid is added. Hydrochloric acid gas is disengaged, and
HYDROCHLORIC ACID.
117
may be collected over mercury. Sodium acid sulphate remains
in the retort.
H2SO4 + NaCl
NaHSO4 + HCl
Sodium chloride. Sodium acid sulphate.
In the arts, the operation is conducted in cast-iron cylinders
or furnaces (Fig. 41), at a high temperature. Under these
conditions, one molecule of sulphuric acid acts upon two mole-
cules of sodium chloride, yielding sodium neutral sulphate,
and two molecules of hydrochloric acid.
H2SO4 +
+ 2NaCl
Na2SO4 + 2HCl
Sodium sulphate.
The hydrochloric acid gas evolved is passed into stoneware
bottles, C, C, C', containing water. It is thus dissolved,
and the solution obtained constitutes the muriatic acid of com-
merce.
A solution of hydrochloric acid may be prepared in the
laboratory by passing the gas through water contained in a
series of Wolff bottles surrounded by cold water, the contents
of the first bottle being rejected (Fig. 42).

FIG. 42.
Composition of Hydrochloric Acid.-The composition of
this gas may be deduced from the following experiments :
118
ELEMENTS OF MODERN CHEMISTRY.
B
A
1. A bottle, B (Fig. 43), the neck of which is adapted by
grinding with emery to the flask A, is filled with dry chlorine;
A, which has exactly the same capacity as
the bottle, is filled with dry hydrogen; the
two vessels are then fitted together, and by
means of the ground joint are hermetically
sealed. The apparatus is now abandoned
for a time to diffuse light, and as the two
gases slowly mix they combine. The union
is completed by exposing the apparatus to
direct sunlight. When the tint of the
chlorine has entirely disappeared, the two
vessels are separated under the surface of
mercury, and it is found that no change in
volume has taken place. The chlorine and
hydrogen have both disappeared to form
hydrochloric acid, which occupies precisely
the same volume as the two primitive gases. Consequently 2
volumes of hydrochloric gas contain 1 volume of chlorine and
1 volume of hydrogen; and if the weight of one volume of
hydrogen (unity) be added to that of one volume of chlorine
(its density compared to hydrogen as unity), the sum will be
the weight of two volumes of hydrochloric acid, and will also
represent the weight of the molecule.

FIG. 43.
Weight of 1 volume of hydrogen
Weight of 1 volume of chlorine
Densities com-
pared to H.
1
•
•
35.5
Weight of 2 volumes of hydrochloric acid 36.5
Densities com-
pared to Air.
0.0693
2.44
2.5093
2. Two volumes of hydrochloric acid gas are passed into a
bent tube over mercury (Fig. 44), and a small piece of sodium
FIG. 44.
is passed up into the bulb and
heated by the flame of a spirit-
lamp. The sodium combines
with the chlorine setting the
hydrogen at liberty, and after
the experiment one volume of
hydrogen remains in the tube.
This second experiment con-
firms the first, both proving
that hydrogen and chlorine.
unite in equal volumes, and
without condensation, to form

IIYDROCHLORIC ACID.
119
hydrochloric acid. One volume of hydrochloric acid contains
half a volume of hydrogen and half a volume of chlorine, but
we cannot admit that the atoms of these elements are divided
into two in the formation of hydrochloric acid; such a sup-
position would be contrary to all ideas of atoms, which repre-
sent the smallest particles of an element that can exist in a
compound. It is more natural to conclude that two vol-
umes of chlorine and two volumes of hydrogen react together
in the formation of hydrochloric acid. Two volumes of
chlorine contain two atoms, constituting one molecule of chlo-
rine. In the same manner two volumes of hydrogen contain
two atoms, constituting one molecule of hydrogen.
Cl Cl
2 volumes or 1 molecule of
chlorine CICI.
=
H
H
2 volumes or 1 molecule of
hydrogen HH.
It is these molecules which are separated into two when
chlorine combines with hydrogen: they exchange their atoms,
and from the exchange, which is a double decomposition, there
result two molecules of hydrochloric acid, which occupy pre-
cisely the same volume as the two molecules of the simple gases.
a+
Cl
H H
2 vols. of chlorine + 2 vols. of hydrogen
H Cl + H Cl
2 vols. of hydro- + 2 vols, of hydro-
chloric acid
chloric acid.
We encounter here again the notion that certain elements in
the free state are composed of molecules, each of which con-
tains two atoms of the same kind. The force which unites
them is not different from affinity. It is affinity which unites
chlorine to chlorine in the molecule of that element; hydrogen
to hydrogen in the molecule of free hydrogen (Gerhardt).
When, however, these two molecules are brought together, the
affinity of chlorine for hydrogen preponderates, and brings about
an exchange, a double decomposition.
Physical Properties.-IIydrochloric acid is a colorless gas
having a pungent odor. It forms thick white fumes in the air
by condensing the atmospheric moisture. It may be liquefied
by a pressure of 40 atmospheres.
It is one of the most soluble of gases in water.
If a jar
filled with this gas and inverted on a plate containing mercury
120
ELEMENTS OF MODERN CHEMISTRY.
The
so that the mouth is sealed, be depressed in the pneumatic
trough, and the plate be then quickly removed, the water im-
mediately rushes into the jar as it would into a vacuum.
shock of the column of water is sometimes sufficient to break
the jar.
One volume of water at 0° dissolves 500 volumes of hydro-
chloric acid; at ordinary temperatures, about 480 volumes.
The water becomes heated and increases in volume. The cold
saturated solution has a density of 1.21 and contains 42.4
per cent. by weight of the dry gas. It is a colorless liquid,
giving off white fumes. When it is heated, it loses a large
quantity of the gas which it holds in solution, but the whole
of the gas is not disengaged, and when the temperature reaches
110° the liquid distils without further loss of gas. A dilute
hydrochloric acid is thus obtained, having a uniform density of
1.10 (Bineau).
Chemical Properties.-Hydrochloric acid is an energetic
acid; it strongly reddens litmus-paper. It is not decomposable
by heat, but is partly decomposed by a series of electric sparks.
All of the metals which decompose water also decompose hy-
drochloric acid with the liberation of hydrogen and the for-
mation of a chloride. Such metals are sodium, zinc, iron,
aluminium, tin, etc.
Hydrochloric acid decomposes the metallic oxides and hy-
drates with the formation of water and a chloride.
If hydrochloric acid be added in small quantities to a con-
centrated solution of potassium hydrate, the liquid becomes
heated and deposits potassium chloride as a crystalline powder.
HCI + KOH
KCI +
Potassium hydrate. Potassium chloride.
H2O
Hydrochloric acid is then a true acid although it contains no
oxygen, for it contains an atom of hydrogen that is replaceable
by an atom of metal. In its action upon potassium hydrate it
resembles nitric acid, for this acid also contains one atom of
hydrogen, which is replaceable by an atom of metal.
HNO3 + KOH
Nitric acid.
KNO3 + II20
Potassium nitrate.
It is seen that the acids are compounds containing a strongly
electro-negative atom or group of atoms, united with hydrogen,
which hydrogen can be replaced by a metal. In nitric acid,
H(NO3), the group NO³ plays the part taken by chlorine in
OXYGEN COMPOUNDS OF CHLORINE.
121
hydrochloric acid; like the chlorine, it renders the hydrogen
replaceable by a metal.
The action of hydrochloric acid upon the metallic oxides is
analogous to that which it exerts upon the hydrates.
If a current of hydrochloric acid be passed over mercuric
oxide contained in a tube (Fig. 45), the oxide becomes heated,

FONDERIEM
FIG. 45.
and is converted into a white powder which is mercuric chlo-
ride; at the same time water is formed and condenses in the
bulb.
HgO + 2HCI
HgCl2 + H2O
Mercuric oxide.
Mercuric chloride.
OXYGEN COMPOUNDS OF CHLORINE.
With oxygen, chlorine forms compounds which may be an-
hydrous or hydrated; the latter are acids.
The oxides are:
Hypochlorous oxide
Chlorous oxide.
Chlorine peroxide.
The acids are:
Hypochlorous acid
Chlorous acid
Chloric acid.
Perchloric acid.
•
C120
C1203
C1204
HCIO
HC102
HC103
HCIO¹
F
11
122
ELEMENTS OF MODERN CHEMISTRY.
HYPOCHLOROUS OXIDE AND ACID.
Hypochlorous oxide is prepared by passing a current of dry
chlorine over mercuric oxide contained in a tube surrounded
by cold water, and may be condensed in a long-necked matrass
placed in a freezing mixture (Fig. 46).
HgO + 2C12
HgCl² + CIO
Mercuric oxide.
Mercuric chloride.

FIG. 46.
The oxide condenses as a brown-red liquid, boiling at 20°.
Above that temperature it is a reddish-yellow vapor, having a
density of 2.977, or, compared to hydrogen as unity, 43.5.
Two volumes of this vapor contain two volumes of chlorine
and one volume of oxygen, a composition represented by the
formula C120.
Hypochlorous oxide is a dangerous body, and cannot be kept
for more than a few hours without spontaneous decomposition;
its vapor frequently explodes.
In combining with the elements of water, hypochlorous oxide
forms hypochlorous acid, the solution of which is almost color-
less.
A} 0 +
H
H
}}
H
0
Cl
}0
+ }0
CI
H
CHLOROUS OXIDE.
123
Preparation of Hypochlorous Acid.-1. A solution of
hypochlorous acid may be prepared by agitating mercuric
oxide with water in jars filled with chlorine gas. The water
will then contain hypochlorous acid and mercuric chloride, and
there remains a brown powder, which is mercury oxychloride
(Balard).
2. A current of chlorine is passed through water holding
recently-precipitated calcium carbonate in suspension. The
latter disappears, carbonic acid gas is disengaged, and the
water becomes charged with calcium chloride and hypochlorous
acid. The mixture is distilled, and the acid which passes with
the water is condensed in a cooled receiver (Wiliamson).
CaCO³ + 2C1² + H²O CO² + CaCl2 + 2HCIO
Calcium Hypochlorous
chloride.
acid.
Calcium
carbonate.
Carbon
dioxide.
Properties of Hypochlorous Acid.-Concentrated hypo-
chlorous acid is a dark-yellow liquid, having the peculiar smell
of chlorinated lime or bleaching-powder. It is very caustic,
and rapidly destroys the skin; its bleaching power is very en-
ergetic, double that of the chlorine it contains. Hydrochloric
acid decomposes it into chlorine and water.
HClO + HCl Cl2 + H2O
CHLOROUS OXIDE.
C1203
Chlorous oxide is formed when potassium chlorate is decom-
posed by dilute nitric acid in the presence of a body capable
of uniting with oxygen, such as arsenious oxide. At a gentle
heat a greenish gas is disengaged which does not liquefy at a
temperature of -20°. This gas is not stable; above 57° it
decomposes with explosion into chlorine and oxygen.
It dissolves in water, forming a dark golden-yellow solution
containing chlorous acid, a body quite unstable itself.
C1203 + H2O
Chlorous oxide.
2HCIO2
Chlorous acid.
124
ELEMENTS OF MODERN CHEMISTRY.
CHLORINE PEROXIDE.
FIG. 47.
3KCIO³ + 2H2SO¹
Potassium
chlorate.
C1204
This compound, which was
discovered by Sir Humphry
Davy, is prepared by the ac-
tion of concentrated sulphuric
acid upon fused potassium
chlorate. The salt is finely
pulverized and added in small
quantities to sulphuric acid
cooled to -10°. The pasty
mass is then introduced into
a small test-tube fitted with a
delivery-tube (Fig. 47), and
is gently heated in a water-
bath; the gas disengaged is
collected in dry jars by down-
ward displacement.
KCIO¹ + 2KHSO¹ + H²O + Cl²O¹

Potassium
perchlorate.
Potassium acid
sulphate.
Chlorine peroxide is a yellow gas having a sweetish aromatic
odor. At -20° it condenses to an orange-red liquid. Its den-
sity in the gaseous state is 33.75 (hydrogen being unity). This
density is anomalous, and indicates that at the instant the liquid
C12O* assumes the gaseous state it is dissociated into two more
simple molecules, CIO² + CIO², which occupy four volumes.
C12 04 is resolved into Cl 02 + CI 02
The density of gaseous chlorine peroxide is then only half
that required by the formula Cl2O¹.
If one volume of hydrogen weighs
one volume of C1204 ought to weigh
But it weighs only
1,
67.5.
33.75,
which proves that Cl²O¹ in the gaseous state occupies four
volumes instead of two.
These four volumes contain, 2 volumes of Cl, weighing 2 × 35.5
4 volumes of 0, weighing 16 × 4
71
61
135
135
Weight of one volume, or density, compared to II
33.75
4
CHLORIC ACID-PERCHLORIC ACID.
125
Chlorine peroxide is a dangerous body; it sometimes de-
composes spontaneously with violent explosions.
It is soluble in water, and the solution may be prepared by
heating on a water-bath a mixture of equal parts of oxalic acid
and potassium chlorate. Carbonic acid and chlorine peroxide
gases are disengaged, and may be passed into water.
Chlorine peroxide is absorbed by alkaline solutions with the
formation of a chlorate and a chlorite.
2KOH + Cl2O t
Potassium hydrate.
KC103
+
KC1O2 + H2O
Potassium chlorate. Potassium chlorite.
CHLORIC ACID.
HCI03
This acid is formed by the spontaneous decomposition of
solutions of hypochlorous and chlorous acids and chlorine per-
oxide.
It may be prepared by treating barium chlorate with dilute
sulphuric acid. Barium sulphate precipitates, and is removed
by filtration, and the solution of chloric acid is concentrated by
evaporation in vacuo.
Chloric acid is a syrupy liquid, ordinarily of a yellow color;
it is not very stable; at a temperature of 40° it commences to
decompose, and at a higher temperature it is resolved into per-
chloric acid, chlorine, oxygen, and water. It has extremely
energetic oxidizing properties; when concentrated, it at once
inflames sulphur, phosphorus, alcohol, and paper. It oxidizes
sulphurous and phosphorous acids and hydrogen sulphide.
With hydrochloric acid it forms water and chlorine.
HC10³ + 5HCI 3H20 + 301²
PERCHLORIC ACID.
HCIO
This is the most rich in oxygen of all the chlorine acids,
and it is a curious circumstance that it is also the most stable.
It may be prepared by distilling potassium perchlorate with
concentrated sulphuric acid. Roscoe obtains it by distilling
chloric acid, which is prepared by decomposing a solution of
potassium chlorate by hydrofluosilicic acid. The insoluble po-
11*
126
ELEMENTS OF MODERN CHEMISTRY.
tassium fluosilicate is separated by filtration, the filtered liquid
is concentrated until white fumes appear, and then the distil-
lation is commenced. The product must be rectified after
being freed from the chlorine which is formed at the same
time.
The perchloric acid thus obtained is a heavy, oily, colorless
liquid, resembling concentrated sulphuric acid. It still con-
tains water, which may be removed by distillation with four
times its weight of concentrated sulphuric acid. . At about
100° dense vapors pass and condense into a very mobile, yellow
liquid; this is the perchloric acid HCIO; the temperature
then rises, and at 200° a liquid passes which solidifies to a
crystalline mass on cooling. These crystals are a hydrate,
HCIO + H2O.
The pure or normal perchloric acid has a density of 1.782
at 15.5°. When brought into contact with water, it combines
with that liquid, producing a hissing noise. Its oxidizing
powers are so energetic that it explodes on contact with paper,
wood, or charcoal. It may be mixed with alcohol, but with
ether it explodes. It cannot be distilled. The hydrate
HCIO* + H2O melts between 50 and 51°.
CHLORIDES OF SULPHUR.
When a current of dry chlorine is passed over sulphur heated
in a retort, a liquid condenses in the receiver which fumes in
the air, has a yellow color, and an irritating, fetid odor. This
is sulphurous chloride, SC. In order that this compound
may be formed, the sulphur must be maintained in excess, and
the operation must be stopped before it has all disappeared.
The product is purified by rectification, that part being collected
which passes at 139°.
When chlorine is passed for several hours through the
chloride of sulphur just described, the yellow color of the
latter changes to deep red. The liquid obtained is mobile,
fumes in the air, and continually disengages chlorine. It can-
not be distilled without decomposition. The product which
passes is at first red, but afterwards assumes a lighter color, and
when the temperature reaches 139° there remains in the retort
only sulphurous chloride, S'CI.
The red liquid has a composition which corresponds to the
formula SC. It is called perchloride of sulphur. Carius
BROMINE.
127
regards it as a mixture of the chloride S'C12 with a tetra-
chloride SCI, corresponding to sulphurous oxide.
SO² sulphur dioxide.
SCI sulphur tetrachloride.
This tetrachloride has been recently isolated by Michaelis,
but it can only exist at a low temperature; it decomposes into
chlorine and sulphurous chloride, S'Cl2, as soon as it is removed
from the freezing mixture where it has been condensed.
The chlorides of sulphur are employed in vulcanizing
caoutchouc.
BROMINE.
Vapor density compared to air
•
5.393
Vapor density compared to hydrogen 77.9 (nearly 80)
Atomic weight Br
80.
Bromium was discovered by Balard in 1826.
Preparation. It is obtained by decomposing potassium
bromide by manganese dioxide and sulphuric acid. Potassium
sulphate and manganese sulphate are formed, and the bromine
is liberated.
2KBr+ MnO² + 2H2SO¹
Potassium Manganeso
bromide. dioxide.
K²SO*+ MnSO¹ + 2H²O+ Br²
Potassium Manganese
sulphate.
sulphate.
The operation is conducted in a tubulated retort, heated on
a sand-bath, and the bromine is condensed in a cooled receiver
fitted to the retort by the aid of an adapter.
The potassium bromide may be replaced by magnesium
bromide, which exists in the mother-liquors of salt-springs.
In this case magnesium sulphate is formed. The mother-
liquors of the soda varech from which the iodine has been ex-
tracted are also employed for the preparation of bromine.
Properties.-Bromine is a dark-red liquid, which solidifies.
at -7.3°. Its density at 15° is 2.99. It boils at 63°, and at
ordinary temperatures gives off red, irritating vapors, for its
vapor tension is considerable even in the cold. It stains the
skin yellow, and immediately corrodes the tissues. It dissolves
in about 33 times its weight of water at 15°, forming an orange-
red solution. At a low temperature it combines with water,
forming a crystalline hydrate, Br² + 10H2O, analogous to that
formed by chlorine.
128
ELEMENTS OF MODERN CHEMISTRY.
Bromine dissolves in carbon disulphide, in chloroform, and in
ether.
Experiment.-A small quantity of solution of potassium
bromide is introduced into a long tube, closed at one end, and
the tube is then nearly filled with chlorine-water; when the two
solutions are mixed, the liquor assumes an orange-red color
from the liberation of the bromine. The tube is now filled up
with ether and agitated briskly, the open end being closed with
the finger. The ether passes through the aqueous solution
and dissolves out all of the bromine, assuming at the same time
a dark-red color.
The affinity of bromine for hydrogen is powerful, but not as
energetic as that of chlorine. Like chlorine, it has remarkable
bleaching properties.
HYDROBROMIC ACID.
Density compared to air
•
Density compared to hydrogen
Molecular weight HBr
2.73
40.5
81.
Preparation. This gas is prepared by the action of water
upon phosphorus tribromide.
PBr3
H³
+ }
03
H³
3
H³
P₁} 0 +
-} o
3HBr
Phosphorus tribromide. 3 molecules water. Phosphorous acid.
The operation may be conveniently conducted in a doubly-
curved tube (Fig. 48). Into the long branch CD fragments of
phosphorus are introduced, carefully separated from each other
by moistened broken glass. The bromine is introduced into
the bend A. The shorter end is then corked, a delivery-tube
adapted to the end D, and the bromine is gently heated until it
boils. The vapor comes into contact with the phosphorus and
forms phosphorus tribromide, but this is at once decomposed
by the water into phosphorous acid and hydrobromic acid.
The latter may be collected in jars over the mercury-trough.
Amorphous phosphorus may be advantageously employed in
this operation, and the process conducted as directed for hydri-
odic acid (Personne).
Properties. Hydrobromic acid is a colorless gas, producing
dense white fumes in the air. A litre of this gas weighs 3.547
grammes. It liquefies at -73°, and may be solidified at a
lower temperature. It is formed by the union of equal volumes
OXYGEN ACIDS OF BROMINE.
129
of bromine vapor and hydrogen without condensation, so that
its composition corresponds to that of hydrochloric acid. It
is
very soluble in water; its concentrated solution fumes in the
air, and is very corrosive.
Chlorine decomposes hydrobromic acid, setting free the
bromine.

A
a
D
FIG. 48.
OXYGEN ACIDS OF BROMINE.
There are known three bromine oxygen acids:
Hypobromous acid, HBrO.
Bromic acid, HBrO³.
Perbromic acid, HBrO¹.
They correspond to hypochlorous, chloric, and perchloric
acids.
Hypobromous Acid, HBrO.-When mercuric oxide is
agitated with an aqueous solution of bromine, a yellowish
liquid is obtained which contains hypobromous acid, and can
be distilled in vacuo. W. Dancer has obtained this acid by the
action of bromine upon silver oxide suspended in water.
2Br² + Ag²0 + H²0
Silver oxide.
2AgBr 2HBrO
Silver bromide.
+
In this process it is necessary to operate rapidly and avoid
F*
130
ELEMENTS OF MODERN CHEMISTRY.
the contact of an excess of silver oxide with the hypobromous
acid, as the latter would be destroyed by the oxide with evolu-
tion of oxygen.
2HBrO + Ag²0 = 2AgBr + H²0 + 0²
#
The solution of hypobromous acid has a yellow color and
bleaching properties analogous to those of hypochlorous acid.
Bromic Acid, HBrO³.-Potassium bromide and potassium
bromate are formed by the action of bromine upon a concen-
trated solution of potassium hydrate. This reaction is similar
to that of chlorine upon potassa.
Kämmerer recommends the preparation of bromic acid by
the action of chlorine upon bromine in presence of water.
5C1² + Br² + 6H²O 10HCl + 2HBrO³
The hydrochloric acid is driven out by evaporation, and
bromic acid remains in the form of a liquid that cannot be con-
centrated to a syrupy consistence without partial decomposition.
Perbromic Acid, HBrO.-Kämmerer has obtained this
acid by decomposing perchloric acid with bromine chlorine is
disengaged. After concentration on a water-bath, the per-
bromic acid remains as a colorless oily liquid. It is relatively
stable, as are the corresponding chlorine and iodine acids. Like
them, it resists the reducing action of sulphurous acid and
hydrogen sulphide.
IODINE.
Vapor density compared to air
8.716
•
127.
Vapor density compared to hydrogen 125.1 (nearly 127)
Atomic weight I
Iodine was discovered by Courtois in 1811, and was studied
by Gay-Lussac in 1813 and 1814.
Natural State.-Iodine is widely disseminated in nature.
It is found in the mineral kingdom combined with various
metals, such as potassium, sodium, calcium, magnesium, silver,
mercury. The alkaline iodides exist in small quantity in sea-
water, in a great number of salt-springs, and in certain rock-
salts. The sodium nitrate found native in Chili contains traces
of sodium iodate, and the mother-liquors from which the nitrate
has been deposited contain enough iodate to be profitably
employed for the preparation of iodine. The ashes of certain
IODINE.
131
sea-plants, such as the algae and fuci, are the most abundant
sources of iodine.
Preparation. The ashes of sea-weeds, called kelp, are ex-
hausted with water and the solution concentrated. Various
salts, such as sodium and potassium sulphates and chlorides
and sodium carbonate, are deposited, and the potassium iodide,
which is contained in smaller quantity than these salts, remains
in the mother-liquor.
A regulated current of chlorine is passed into this solution
as long as it continues to set free iodine, which is deposited as
a pulverulent, black precipitate. An excess of chlorine must
be avoided, as this would redissolve a portion of the iodine,
forming iodine chloride.
Another process consists in mixing the mother-liquor with
ordinary nitric acid and gently heating the mixture. The alka-
line iodide is decomposed by the acid, a nitrate is formed, red
vapors are disengaged, and iodine is set free.
4HNO3 + 2KI
Nitric
acid.
Potassium
iodide.
2KNO³ + 2NO² + 2H2O + Ľ²
Potassium
nitrate.
Nitrogen
peroxide.
The precipitated iodine is collected, drained, and after drying
is sublimed in stoneware vessels.
The same process that has been described for the manufacture
of bromine from potassium bromide may also be applied for the
extraction of iodine. It consists in treating the iodide with
manganese dioxide and sulphuric acid.
Properties of Iodine. The iodine obtained by sublimation
occurs as scales or crystalline plates, having a brilliant, dark
bluish-gray surface, and a density of 4.948 at 17°. It may be
obtained crystallized in rhombic octahedra by exposing to the
air a solution of hydriodic acid.
Iodine melts at 107°. It boils at about 175°, but volatilizes
sensibly at ordinary temperatures. Its vapor has an intense
rich violet color. A litre of this vapor weighs 11.32 grammes.
Iodine is but very slightly soluble in water; one part of
iodine requires 7000 parts of water for its solution, but com-
municates a light-brown color to the whole of that liquid.
Alcohol and ether dissolve iodine freely, forming dark-brown
solutions. Carbon disulphide, benzine, and chloroform also
dissolve it, assuming a beautiful violet color.
Experiment.--If a few drops of chlorine-water be added to
a very dilute solution of potassium iodide, the chlorine will
132
ELEMENTS OF MODERN CHEMISTRY.
combine with the potassium, displacing the iodine, which will
color the liquid brown; if now the solution be agitated with a
small quantity of chloroform, the latter will take up all of the
iodine, assuming a violet color.
Iodine strikes an intense blue color with starch. The reac-
tion is very delicate and permits the detection of the smallest
trace of free iodine.
Experiment.-If a few drops of a solution of potassium.
iodide be added to a solution of starch, no coloration takes
place, because the iodine is in combination; but if a drop or
two of chlorine-water be added, the iodine will be set free, and
combining with the starch will at once produce the character-
istic blue color. An excess of chlorine will again destroy the
color.
HYDRIODIC ACID.
Density compared to air
Density compared to hydrogen
Molecular weight HI
4.443
64.1
128.
Preparation.-Hydriodic acid is prepared by the action of
iodine upon phosphorus in presence of water; phosphorus
triiodide is first formed, and this is decomposed into phos-
phorous acid and hydriodic acid.
PI³ +
Phosphorus
triiodide.
H³)
}
303
3 molecules
of water.
P
3
}00
H³)
0³ + 3HI
Phosphorous
acid.
Amorphous phosphorus in powder is introduced into a glass-
stoppered retort the neck of which is soldered to the delivery-
tube (Fig. 49), and covered with a layer of water; the iodine
is then added, and on the application of a gentle heat a regular
current of hydriodic acid is obtained. The gas may be col-
lected, like chlorine, by downward displacement in dry jars.
Properties. Hydriodic acid is a colorless gas producing
white fumes in the air. It may be condensed to a yellow
liquid by strong pressure or intense cold, and can even be solid-
ified. Dry oxygen decomposes it at a high temperature, water
being formed and the iodine being set at liberty.
If a lighted taper be applied to a mixture of hydriodic acid
and oxygen, the violet vapor of the iodine set free is instantly
apparent.
This decomposition of hydriodic acid by oxygen takes place
at ordinary temperatures in the presence of water. A solution
HYDRIODIC ACID.
133
of hydriodic acid exposed to the air rapidly becomes brown,
and after a time deposits crystals of iodine.
Solution of hydriodic acid is prepared by passing the gas into
water cooled to 0°. It may also be made by passing a current
of hydrogen sulphide through water holding iodine in suspen-
sion; hydriodic acid is formed, and sulphur is precipitated.
H2S+ I² 2HI+S
The saturated solution of hydriodic acid has a density of
1.7, and fumes in the air. When freshly prepared, it is color-

2
FIG. 49.
less; when heated, it loses part of its gas, and finally distils
unaltered at 126°. The saturated solution contains 57.7 per
cent. of the dry acid.
Chlorine and bromine at once decompose hydriodic acid,
combining with the hydrogen and setting free the iodine. The
experiment may be made by pouring a few drops of bromine.
into a jar filled with hydriodic acid gas, when the appearance
of a violet vapor immediately indicates the liberation of iodine.
Potassium, zinc, iron, mercury, and silver decompose hydri-
odic acid, but with unequal energies, setting free the hydrogen.
12
134
ELEMENTS OF MODERN CHEMISTRY.
Sulphuric acid also decomposes it, and is itself reduced to sul
phurous oxide.
H2SO4 + 2HI 2H2O + SO2 + I²
Nitric acid is still more readily reduced by hydriodic acid.
2HNO3 +
+ 2HI
2H2O + 2N02 + I²
Nitric acid.
Nitrogen peroxide.
IODINE OXIDES AND OXYGEN ACIDS.
Among the compounds of iodine and oxygen, iodic and peri-
odic oxides are the only ones known with certainty. The ex-
istence of the other oxides, although possible and even probable,
has not been fully demonstrated. These compounds would form
the following series:
Hypoiodous oxide
Iodous oxide
+
Iodine peroxide
Iodic oxide
Periodic oxide
•
120
1203
1204
1205
•
1207
In combining with water, these oxides form acids; it is only
necessary to describe here iodic and periodic acids.
120³ + H2O
2HIO³,2 molecules iodic acid.
120² + H2O = 2HIO',2 molecules periodic acid.
H²O
IODIC ACID.
IO2(OH)
HIO3
Iodic acid is formed when iodine is submitted to the action
of energetic oxidizing agents, such as concentrated nitric acid
or a mixture of nitric acid and potassium chlorate. It is also
formed by the action of an excess of chlorine on iodine in
presence of water.
I² + 5C1² + 6H²O 10HCl + 2HIO³
Preparation. Iodic acid may be conveniently prepared by
heating iodine and potassium chlorate with dilute nitric acid.
The oxygen of the chlorate oxidizes the iodine to iodic acid,
and on adding barium nitrate to the liquid, barium iodate is
precipitated. The latter salt is decomposed by sulphuric acid;
iodic acid is set free in the solution, and barium sulphate is
precipitated; the filtered solution is concentrated by evapora-
tion in vacuo.
Properties.-Iodic acid is solid, and crystallizes in hex-
agonal tables. When heated to 170° it loses water and is
PERIODIC ACID.
135
converted into iodic oxide, and at a red heat the latter is
decomposed into iodine and oxygen.
It is seen that iodic acid is much more stable than its ana-
logue, chloric acid; nevertheless it is easily reduced by bodies
avid of oxygen.
If sulphurous acid be added to a solution of iodic acid, a
precipitate of iodine is formed instantly, but an excess of sul-
phurous acid redissolves the precipitate, part of the water being
decomposed and hydriodic and sulphuric acids being formed.
Iodic acid is also decomposed by hydriodic acid. If a solu-
tion of iodic acid be poured into a solution of starch, no color-
ation appears, but the characteristic blue color is at once
developed on adding a drop of hydriodic acid.
HIO³ + 5HI
3H20 + 31²
PERIODIC ACID.
This acid has been obtained from disodic periodate, a salt
which is precipitated when a current of chlorine is passed
through a solution of sodium iodate mixed with sodium hydrate.
NaIO3 + 3NaOH + Cl²
Sodium iodate. Sodium hydrate.
I05
{
Na²
{H¨‚H³O + 2NaCl
Disodic periodate. Sodium chloride.
The crystalline precipitate is dissolved in nitric acid, and
lead nitrate is added to the solution; lead periodate is precipi-
tated, and this salt is exactly decomposed by sulphuric acid;
the liquid is filtered to separate the lead sulphate, and evapo-
rated at a gentle heat. The periodic acid crystallizes out in
colorless, deliquescent, rhombic prisms, fusible at 130°. These
crystals contain H³IO + H2O. At 160° they lose water and
are converted into a white mass of periodic oxide.
2(H³10.H2O) I'О' + 5H20
Between 180 and 190° periodic oxide abandons oxygen,
is converted into iodic oxide, 1205.
Periodic acid forms several varieties of salts.
There is a diargontic periodate, IOS {A,HO
IO2<
(OAg)*
OH
H'
and
+ H2O, corresponding to the disodic salt before
mentioned; but there is also a silver periodate, AgIO*, to
which corresponds an acid, HIO, having a composition analo-
gous to that of perchloric acid, but which has not yet been
obtained.
136
ELEMENTS OF MODERN CHEMISTRY.
Analogy between Chlorine, Bromine, and Iodine. Chlo-
rine, bromine, and iodine present a striking analogy in their
chemical properties, and this analogy is seen in all of their
compounds. They combine with hydrogen, atom for atom,
forming the acids
HCI
HBr
HI
and it is seen that the atoms of chlorine, bromine, and iodine
are equivalent to each other and to an atom of hydrogen; each
of these elements is monatomic.
Their affinities for hydrogen are far from being equal; in this
respect chlorine is more powerful than bromine, and bromine
than iodine. The contrary has been noticed regarding their
affinities for oxygen, for the oxygen acids of iodine are more
stable than those of chlorine.
The analogy between these three elements is followed out
in the constitution of their oxides and acids, and in their com-
binations with the metals. The chlorides, iodides, and bro-
mides possess in general the same constitution, and it is to be
remarked that the greater part of these binary compounds are
soluble in water and are crystallizable like salts, of which they
otherwise present the characters. Hence the name halogen
bodies, which was applied by Berzelius to this group of elements,
to indicate that they form salts in combining with the metals.
FLUORINE.
Fl 19.
This is a body belonging to the same group just considered,
and having a chemical energy much superior to that of chlorine.
It exists in the common mineral fluor spar, which is a combina-
tion of fluorine and calcium. But fluorine has never been
isolated; it attacks all vessels, and it would be necessary to
have apparatus and vessels cut from fluor spar in order to con-
tain it. There is a compound of fluorine and hydrogen.
HYDROFLUORIC ACID.
Molecular weight HF1.
20
This compound is prepared by decomposing powdered cal-
cium fluoride with sulphuric acid.
CaFl² + H²SO¹
Calcium fluoride.
CaSO¹+
2HFI
Calcium sulphate.
HYDROFLUORIC ACID.
137
The operation is conducted in a leaden retort, to which is
adapted a receiver of the same metal surrounded by a freezing
mixture (Fig. 50).

The
hydrofluoric
acid condenses as
a very acid liquid,
which fumes strong-
ly in the air. Its
density is 1.06. In
this state it still re-
tains water; but
Fremy obtained it
anhydrous by de-
composing dry hy-
drofluoride of fluor-
ide of potassium,
KF1,HF1, by heat
FIG. 50.
in a platinum retort. This salt breaks up into potassium fluor-
ide, which remains, and hydrofluoric acid, which is disengaged
and must be condensed in a platinum receiver cooled to −20°.
Pure and anhydrous hydrofluoric acid is liquid at ordinary tem-
peratures; it is very mobile, and boils at 19.4° (Gore). It is
extremely corrosive, and manipulations with it should be con-
ducted with great care. Its affinity for water is so great that
each drop of the acid let fall into that liquid produces a hissing
noise, as would a red-hot iron. The solution is employed for
etching upon glass, for hydrofluoric acid attacks and corrodes
that substance. This effect is due to the action of the acid
upon the silica of the glass, which it converts into either sili-
con fluoride or hydrofluosilicic acid, as will be seen farther on.

FIG. 51.
A design may readily be engraved on glass by covering the
glass with a thin coating of wax, through which the design is
12*
138
ELEMENTS OF MODERN CHEMISTRY.
traced with a sharp point; the glass is then placed over a leaden
capsule containing a mixture of powdered calcium fluoride, and
sulphuric acid (Fig. 51), which is gently heated by a spirit-lamp.
Hydrofluoric acid vapor is disengaged and attacks the glass
wherever it is not protected by the wax. When the wax is re-
moved, the design is found to be permanently etched on the glass.
A dilute solution of hydrofluoric acid or a bath of hydro-
fluoride of potassium fluoride may be employed instead of the
vapor in the former experiment, but in this case the etched
portions are transparent and not opaque as when produced by
the vapor; they may be rendered opaque by adding a salt, such
as potassium or ammonium sulphate, to the bath.
NITROGEN.
Density compared to air.
Density compared to hydrogen
Atomic weight N
0.9714
14.1
14.
Nitrogen is one of the elements of the air, and it was from
air that it was first obtained in a pure state by Lavoisier and
Scheele, in 1777. To obtain nitrogen from the atmosphere it
is only necessary to remove the other element, oxygen.
Preparation. A flat piece of cork, B (Fig. 52), floating in
the pneumatic-trough, supports a small capsule containing a
FIG. 52.
fragment of phos-
phorus. The latter
is inflamed, and the
capsule immediately
covered with a bell-
jar. The heat pro-
duced by the com-
bustion at first ex-
pands the air and
drives out a portion,
but in a few minutes
the water rises in
the jar, taking the
place of the oxygen
which has been con-
sumed. When the

phosphorus is extinguished, the experiment has terminated.
The water gradually dissolves the white smoke of phosphoric
oxide which fills the jar, and there remains a colorless, irre-
AMMONIA.
139
spirable gas that will not support combustion. This gas is
nitrogen, still mixed with traces of oxygen and carbonic acid gas.
Pure nitrogen may be obtained by passing a current of air,
previously freed from moisture and carbon dioxide, through a
porcelain tube containing incandescent copper. The copper
absorbs the oxygen, and pure nitrogen passes out at the end
of the tube and may be collected over the pneumatic trough.
Pure nitrogen may also be obtained by heating ammonium
nitrite in a glass retort; heat decomposes this salt into nitrogen
and water.
(NH4)NO²
Ammonium nitrite.
2H2O + N2
Properties.-Nitrogen is a colorless gas, somewhat lighter
than the air. A litre of this gas weighs 1.257 grammes.
It
extinguishes burning bodies, and is not combustible itself; it
produces no precipitate in lime-water. Water dissolves only
of its volume of nitrogen at 0°. Animals are quickly suffo-
cated in an atmosphere of pure nitrogen, but the gas does not
exert a poisonous influence upon the economy.
50
The affinities of nitrogen are not energetic. It combines
directly with only a very small number of elements, among
which may be mentioned carbon, silicon, boron, and titanium.
Under the influence of a series of electric discharges it will
unite with oxygen, forming nitrogen peroxide; with hydrogen,
forming ammonia.
ΑΜΜΟΝΙΑ.
Density compared to air
Density compared to hydrogen
Molecular weight NH³
0.596
8.60
17.
Ammonia was discovered by Priestley, studied by Scheele,
and analyzed by Bertholet in 1785.
Preparation.-Equal weights of quick-lime and sal am-
moniac, both in powder, are rapidly mixed in a mortar, and
the mixture introduced into a glass flask, which is then filled
up with fragments of quick-lime. A cork and delivery-tube
are adapted to the flask, which is then gently heated and the
gas disengaged collected over mercury.
The calcium oxide or lime decomposes the ammonium
chloride (sal ammoniac), with the formation of calcium
chloride, ammonia gas, and water; the latter is absorbed by
the fragments of lime which fill up the flask.
2NH*C1 + CaO 2NH³ + CaCl2 + H2O
Ammonium chloride. Calcium oxide. Ammonia.
Calcium chloride.
140
ELEMENTS OF MODERN CHEMISTRY.
A solution of ammonia in water may be prepared by passing
the gas through a series of Wolff's bottles, about half filled with
water, excepting the first, which should only contain a small
quantity destined to wash the gas.
Physical Properties.-Ammonia is a colorless gas, having
a powerful and pungent odor, which excites tears. Its taste is
burning and caustic. It may be liquefied by a temperature of
-40°, or at 10° under a pressure of 63 atmospheres. Fara-
day's method of liquefying it is as follows: ammonia is passed
over dry silver chloride, by which it is absorbed. The silver
chloride, saturated with ammonia, is introduced into a bent
tube (Fig. 53), the empty limb of which is then sealed at the


FIG. 53.
FIG. 54.
blow-pipe. The end containing the chloride is now heated in
a water-bath, while the empty end is cooled in a freezing mix-
ture (Fig. 54). The animonia is driven out from the silver
chloride, and condenses into a transparent liquid in the cooler
branch. Faraday succeeded in solidifying ammonia by subject-
ing this liquid to rapid evaporation. In the solid state it is a
white, crystalline, transparent substance, fusible at -75°, and
having only a feeble odor. According to Bunsen, liquid ammo-
nia boils at -35° under a pressure of 0.7493 metre; its density
is 0.76.
Ammonia gas is very soluble in water, which dissolves 1000
times its volume at 0°, and about 740 times its volume at
15°. The rapid absorption of ammonia by water may be strik-
ingly shown by the following experiment. A bottle, A (Fig. 55),
is filled with ammonia gas, and fitted with a cork, through
which passes a tube drawn out at both extremities, and the
outer end of which is sealed. If this end be plunged under
water and the point be broken off, the water at once rises into
AMMONIA.
141
the bottle, forming a fountain, and the vessel becomes filled
with water in a very short time.
The aqueous solution of ammonia possesses the odor of the
gas; it is caustic, and

Its
was formerly called vol-
atile alkali and spirits
of hartshorn. It is
largely used in the arts
and as a reagent.
density is 0.855. When
heated, it loses ammonia
gas, the whole of which
may be driven out by
boiling.
Composition of Am-
monia.-200 volumes
of ammonia gas are in-
troduced into an eudi-
ometer, and electric
sparks are passed
through the gas for
some time by means of
a Ruhmkorff coil (Fig.
FIG. 55.
56). When the experiment has terminated, the volume of
gas will be found to have doubled. 200 volumes of oxygen
are added to the 400 volumes of gas thus obtained, and a spark
is passed; an explosion takes place, and after making the

FIG. 56.
necessary corrections for temperature and pressure, the 600
volumes of gas are found to be reduced to 150 volumes; 450
volumes have thus disappeared to form water.
142
ELEMENTS OF MODERN CHEMISTRY.
These 450 volumes must have contained
300 volumes of hydrogen,
150 volumes of oxygen.
Consequently the 200 volumes of ammonia gas, which were
decomposed by the spark into 400 volumes, must have been
formed by the union of
300 volumes of hydrogen,
100 volumes of nitrogen.
The latter gas remains in the eudiometer, together with the
50 volumes of oxygen that were employed in excess.
From this analysis it is seen that two volumes of ammonia
contain three volumes of hydrogen and one volume of nitrogen,
a composition which is expressed by the formula NH³.
Chemical Properties.-Ammonia gas is decomposed by a
high temperature, as by a series of electric sparks. The experi-
ment may be made by passing the gas through a porcelain tube

FIG. 57.
filled with fragments of broken porcelain and heated to white-
ness, and collecting the gas resulting from the decomposition in
vessels filled with water (Fig. 57). This gas is found to be a
mixture of three volumes of hydrogen and one volume of
nitrogen.
The decomposition takes place more readily if iron, copper,
or platinum wires be introduced into the porcelain tube. The
AMMONIA.
143
latter metal is not altered, but the iron and copper become
brittle and retain a few per cent. of nitrogen. The decompo-
sition of the ammonia seems here to be favored by the forma-
tion of metallic nitrides, unstable compounds which are almost
entirely decomposed by the prolonged action of the heat.
Ammonia gas will not burn in the air, but a mixture of four
volumes of ammonia and three volumes of oxygen will explode
on the application of a flame.
2NH³ + 0³
3H2O + N²
Ammonia will burn in an atmosphere of oxygen. A jet of
ammonia escaping

through a tube drawn
out to a point may be
ignited on the instant
that it is plunged into
a jar of oxygen, and
will continue to burn
with a yellowish flame
until the oxygen
is
consumed (Fig. 58).
Independently of
this rapid combus-
tion, ammonia may
undergo a slow com-
bustion under the fol-
lowing conditions:
FIG. 58.
The vessel A (Fig. 59) contains a solution of ammonia,
above which is suspended a spiral of platinum wire. The solu-
tion is gently heated, and a rapid current of oxygen gas is
forced through it. The mixed ammonia and oxygen gases
come in contact with the platinum spiral and combine together,
their union developing so much heat that the spiral is heated
to redness. The vessel sometimes becomes filled with white
fumes of ammonium nitrite. The nitrous acid is produced by
the slow oxidation of the ammonia. If a mixture of oxygen
and ammonia gases he passed through a heated tube contain-
ing spongy platinum, nitric acid and water will be formed
and disengaged in vapor.
Action of Chlorine and Iodine upon Ammonia.—Chlorine
instantly decomposes ammonia, combining with its hydrogen.
If a drawn-out tube through which a jet of ammonia is escaping
144
ELEMENTS OF MODERN CHEMISTRY.
be plunged into a bottle filled with dry chlorine (Fig. 60), the
ammonia takes fire immediately, and white vapors of ammo-
nium chloride are formed.
4NH³ + Cl³
3NH4Cl + N
If a long tube closed at one end be almost entirely filled
with saturated chlorine water and then filled up with a solu-
السور
FIG. 59.
A
tion of ammonia, and quickly
inverted on the pneumatic
trough, the lighter solution of
ammonia will rise through the
chlorine-water and will be de-
composed according to the pre-
ceding equation. Ammonium
chloride will remain in solution,
while the nitrogen will collect
at the top of the tube.
Nitrogen Chloride. Under
other conditions the nitrogen
may combine with the chlorine,
forming a very explosive and
dangerous compound, nitrogen
chloride.
This experiment may be made.
as follows: A small jar of chlo-
rine is inverted in a saucer con-
taining a solution of ammonium chloride. The ammonia of
this salt is slowly decomposed by the chlorine, with the for-
mation of hydrochloric acid and
nitrogen chloride.


FIG. 60.
This
As the chlorine is absorbed, the
level of the liquid in the jar rises
and a drop of a yellow liquid soon
collects on the surface. A light tap
on the vessel causes it to sink through
the solution into the saucer.
oily body is nitrogen chloride. The
jar may now be removed and a small
piece of phosphorus thrown into the
saucer, and pushed from a distance
towards the drop of nitrogen chloride
by the aid of a long wooden rod.
AMMONIA.
145
As soon as the two substances come into contact, the nitrogen
chloride explodes and the saucer is broken into pieces.
The formula NCI³ has been attributed to this body.
Nitrogen Iodide.-There is another explosive compound
analogous to nitrogen chloride, but containing iodine. It is
obtained as a black powder by treating powdered iodine with
ammonia; when dry it explodes with great violence on the
lightest touch, and sometimes spontaneously. Bunsen has
attributed to it the formula N²H³Ï³.
According to Stahlschmidt, the composition of nitrogen
iodide corresponds to the formula NI³, when this body is pre-
pared by the action of an alcoholic solution of iodine upon
aqueous ammonia; but if both bodies be in alcoholic solution,
an iodide is obtained having the formula NHI².
If this be correct, these bodies present very simple relations
with ammonia.
H
CI
I
I
N
H
N CI
NI
NI
H
Cl
I
(H
Ammonia. Nitrogen chloride.
Trichlorammonia.
Triiodammonia. Diiodammonia.
Nitrogen iodides.
The substitution of the chlorine or iodine for hydrogen takes
place atom for atom.
Action of Potassium upon Ammonia.-When potassium
is heated in an atmosphere of ammonia, the brilliant surface
of the metal becomes covered with a greenish-black liquid,
and at the same time hydrogen is disengaged. The metal
entirely disappears little by little, and, on cooling, the liquid
solidifies to an olive-green mass. This substance represents
ammonia in which one atom of hydrogen has been replaced
by an atom of potassium.
H
HN
H
K
Ammonia. HN Potassium amide.
H
When it is treated with water, ammonia is regenerated and
potassium hydrate is formed.
KNH2 + H2O
Potassium amide.
+
KOH +
Potassium hydrate.
NH³
Ammonium Amalgam.-If liquid amalgam of potassium
or sodium and mercury be treated with a saturated solution of
ammonium chloride, the amalgam increases in volume, assumes
a buttery consistence, and is converted into a soft, light mass
G
13
146
ELEMENTS OF MODERN CHEMISTRY.
having the metallic lustre of mercury. It will retain the
impression of the finger and will float upon water; but it
gradually decomposes, losing hydrogen and ammonia, and only
mercury remains. This unstable body is called ammonium
amalgam. In it the mercury is combined with a group, NH¹,
which contains all of the hydrogen of the ammonium chloride,
the chlorine of which has combined with the potassium.
NH³.HCI
Ammonium chloride.
CI
NH¹
Radical ammonium.
It has recently been found that the ammonium amalgam is
very compressible, and that its diminution in volume under
pressure sensibly follows Mariotte's law. It has hence been
concluded that the ammonium does not exist in combination
with the mercury, and that the increased volume of the latter
is due simply to an absorption of gas. It is difficult to admit
this, for the compressibility of the ammonium amalgam proves
only that the compound has no stability, and begins to decom-
pose almost immediately on its formation. The disengaged
gases, which are in the exact proportion NH3+H, may be
retained by the pasty amalgam remaining: they could not be
absorbed by the liquid mercury.
Ammonium Theory. The reaction which has just been
described is of great importance, and directly supports the
ammonium theory suggested by Ampère. According to this
theory, the ammoniacal salts are analogous in constitution to
ordinary salts, from which they differ only by the substitution
of a compound radical, ammonium, for a simple radical. The
following formulæ explain this proposition:
NH³.HCI
NH.HNO3
NH3.HS
(NH3)2.H'S
(NH¹)Cl analogous to
Ammonium chloride.
(NH¹) NO³ analogous to
Ammonium nitrate,
NH4
H
KC
S analogous to S
Ammonium sulphydrate.
Potassium chloride.
KNO³
Potassium nitrate.
K
H
K
Κ
S
KS
}
Potassium sulphide.
Potassium sulphydrate.
NHS analogous to
Ammonium sulphide.
AMMONIUM CHLORIDE.
NHẠC
This salt was formerly obtained from Egypt, where it was
made by subliming the soot produced by the combustion of
AMMONIUM SULPHYDRATE AND AMMONIUM SULPHIDE. 147
camel's dung. It is now prepared in large quantities from gas-
liquor, or the water condensed in the manufacture and purifi-
cation of illuminating gas from coal. This liquor is heated
with lime, ammonia is disengaged and is conducted into hydro-
chloric acid. Ammonium chloride is obtained by simply
evaporating the solution. It is purified by sublimation in
stoneware pots which are heated in a furnace out of which the
upper parts of the pots project. There the volatilized chloride
condenses, and the sublimed product is known in commerce as
sal ammoniac, or muriate of ammonia.
It generally occurs as white or grayish, compact masses,
having a crystalline fibrous structure. Its taste is sharp and
salty. It dissolves in two and a half parts of cold, and in its
own weight of boiling water. It is deposited from a satu-
rated solution in small octahedra, grouped together in needles,
and presenting a fern-leaf-like appearance. At a high tem-
perature it volatilizes without melting and sublimes without
decomposition.
Ammonium chloride is formed by the union of equal vol-
umes of hydrochloric acid and ammonia gases.
AMMONIUM SULPHYDRATE AND AMMONIUM
SULPHIDE.
Hydrogen sulphide and ammonia gases unite in the cold
in two different proportions, forming two compounds, ammo-
nium sulphydrate and ammonium sulphide.
H2S +
Hyrogen sulphide.
(2 vol.)
H2S
Hydrogen sulphide.
(2 vol.)
+
NH³
Ammonia.
(2 vol.)
2NH³
Ammonia.
(4 vol.)
S
NH¹
Н HS
Ammonium sulphydrate.
NH"}
S
Ammonium sulphide.
These compounds are definite, but are decomposed into their
elements by heat. Horstmann and Salet have shown that hy-
drogen sulphide and ammonia gases may be mixed in all pro-
portions without contraction in volume taking place, provided
the temperature be maintained above 60°.
Ammonium sulphydrate is generally obtained in solution by
saturating aqueous ammonia with hydrogen sulphide. This
solution is colorless, but acquires a yellow color on exposure to
148
ELEMENTS OF MODERN CHEMISTRY.
the air. When a quantity of ammonia is added to it equal to
that which it already contains, ammonium sulphide, (NH)'S,
is formed, which corresponds to potassium sulphide, K³S.
Ammonium sulphide is largely employed in the laboratory
as a reagent for the detection of certain metals.
If ammonium sulphide be added to a solution of ferrous
sulphate, a double decomposition takes place; ammonium sul-
phate is formed and remains in solution, while ferrous sulphide
forms a black precipitate.
FeSO¹ + (NH*)S
Ferrous sulphate.
FeS + (NH4)2SO4
Ferrous sulphide. Ammonium sulphate.
The salts of zinc, manganese, cobalt, and nickel are likewise
precipitated as sulphides by ammonium sulphide.
The salts of aluminium and chromium are precipitated as
hydrates, hydrogen sulphide being disengaged.
The preceding salts are not precipitated by hydrogen sul-
phide (the zinc salts are not precipitated if they be acid), but
the latter reagent precipitates in the form of sulphides the salts
of lead, bismuth, copper, cadmium, mercury, silver, antimony,
tin, gold, and platinum. The sulphides of the latter four
metals dissolve in an excess of ammonium sulphide.
The sulphides of arsenic, tin, antimony, gold, and platinum
all form compounds with ammonium sulphide, in which the
latter plays the part of a base.
AMMONIUM NITRATE.
(NH4) NO3
Ammonium nitrate is prepared by saturating nitric acid
with ammonia. It crystallizes in large, transparent, fusible
prisms, which are very soluble in water and produce a notable
depression of temperature in the act of solution, extending
even to -15°. At 300° ammonium nitrate is decomposed
into nitrogen monoxide and water. It is used for the prepa-
ration of nitrogen monoxide, much used as an anesthetic.
AMMONIUM CARBONATE.
When dry carbon dioxide and ammonia gases are mixed in
the proportion of 2 volumes of the first to 4 volumes of the
second, they condense, forming a white powder, which is am-
AMMONIUM SULPHATE-HYDROXYLAMINE.
149
monium carbamate, a compound which was formerly called
anhydrous carbonate of ammonia.
CO² + 2NH³
CO
NH2
ONH¹
Ammonium carbamate.
The ammonium carbonate of commerce is generally consid-
ered as a sesquicarbonate. It contains 2[CO²(NH)²] + CO² +
2H2O. It is obtained by heating a mixture of equal parts of
ammonium sulphate and chalk in a subliming apparatus.
Ammonia and water are disengaged, and the sesquicarbonate
of ammonium sublimes.
Recently sublimed ammonium sesquicarbonate is transparent
and crystalline. It has a strong ammoniacal odor and a sharp
caustic taste. When exposed to the air it gradually loses
ammonia and is converted into ammonium acid carbonate.
Ammonium Acid Carbonate. This salt, which is com-
monly known as bicarbonate of ammonia, may be obtained by
passing a current of carbonic acid gas into aqueous ammonia,
to saturation. The acid salt is deposited in right rhombic
prisms. The neutral carbonate of ammonium is not known.
These salts present the following relations to the hypothetical
carbonic acid:
OH
COOH
Carbonic acid.
(Hypothetical.)
co<
ONH¹
OH
ONH+
CO
Co<
ONH
Ammonium acid
Ammonium
carbonate.
carbonate.
AMMONIUM SULPHATE.
(NH4)2SO4
This salt is obtained in the arts by passing the ammonia
that is disengaged when gas-liquor is heated with lime into
dilute sulphuric acid. It crystallizes in right rhombic prisms.
It is colorless and has a sharp taste. It dissolves in two
parts of cold, and in its own weight of boiling, water. It is
insoluble in alcohol.
HYDROXYLAMINE.
NH2(OH)
This remarkable compound was discovered by Lossen. It
is formed when ethyl nitrate is reduced by tin and hydrochlo-
ric acid. It is also a product of the action of dilute nitric acid-
upon tin, and that of hydrochloric acid and tin upon ammo-
nium nitrate.
13*
150
ELEMENTS OF MODERN CHEMISTRY.
Finally, Lossen has prepared it synthetically by passing a
current of nitrogen dioxide over tin moistened with hydro-
chloric acid, which determines a disengagement of hydrogen.
2NO + 3H2
2[NH²(OH)]
In the first reactions the nitric acid is reduced by the hy-
drogen resulting from the action of a dilute acid upon tin, and
which is then, just as it is set free, in what is called the nascent
state.
HNO³ + 3H² = 2H2O + NH².OH
Nitric acid.
The hydroxylamine thus formed remains in the liquid com-
bined with an excess of acid. It possesses the properties of an
energetic base. It forms definite salts with the acids, and can
be regarded as ammonia, in which the group OH (hydroxyl)
has been substituted for one atom of hydrogen.
H
NH
H
OH
NH
H
Hydroxylamine.
Ammonia.
Thus far it has not been isolated; when a solution of potas-
sium hydrate is added to a concentrated solution of a salt of
hydroxylamine, nitrogen is disengaged and ammonia is formed.
3(NH2.OH) N² + NH³ + 3H20
Lossen has obtained an aqueous solution of hydroxylamine
by decomposing a dilute solution of hydroxylamine sulphate
with the exact quantity of baryta-water sufficient to precipitate
the sulphuric acid.
Hydroxylamine possesses reducing properties; it precipi-
tates copper and mercury in the metallic state from solutions
of their salts.
OXYGEN COMPOUNDS OF NITROGEN.
Five compounds of nitrogen and oxygen are known.
Nitrogen monoxide, or nitrous
oxide
Nitrogen dioxide.
Nitrogen trioxide
ATOMIC
COMPOSITION.
VOLUMETRIC COMPOSITION.
N20
NO
2 vol. N and 1 v. O condensed in 2 v.
1 vol. N and 1 v. 0
===
N203
Nitrogen tetroxide, or nitrogen
peroxide.
•
Nitrogen pentoxide, or nitric
anhydride
2 v.
2 vol. N and 3 v. O condensed in 2 v.
N204 2 vol. N and 4 v. O condensed in 2 v.
N205 2 vol. N and 5 v. O condensed in 2 v.
NITROGEN MONOXIDE.
151
Nitrogen trioxide and nitrogen pentoxide combine with
water, forming nitrous and nitric acids.
2HNO²
N203 +
II20
Nitrogen trioxide.
N205 +
H2O
Nitrogen pentoxide.
Nitrous acid.
2HNO³
Nitric acid.
NITROGEN MONOXIDE.
Density compared to air
•
Density compared to hydrogen
Molecular weight N20
1.527
22.
41.
This gas, known also as protoxide of nitrogen, nitrous oxide,
and laughing-gas, was discovered by Priestley in 1776.
Preparation. It is obtained by gently heating ammonium
nitrate in a glass retort. The salt melts, and then decomposes

FIG. 61.
with effervescence into water and nitrogen monoxide, which
may be collected over water (Fig. 61).
(NH)NO³ N2O + 2H2O
Properties.-Nitrogen monoxide is colorless and odorless,
but possesses a sweetish taste. It is not permanent, and may
be liquefied by strong pressure. It is liquefied on a consider-
able scale at present, that it may be transported in small bulk
for the use of dentists. For this purpose it is compressed in
strong iron reservoirs.
A remarkable experiment can be performed as follows: A
quantity of liquid nitrogen monoxide is poured into a test-tube
fixed by a cork in the neck of a bottle; a portion of it
instantly volatilizes, producing intense cold. If now a little
mercury be poured into the tube, it will sink through the
liquid monoxide and immediately be solidified. A small piece
152
ELEMENTS OF MODERN CHEMISTRY.
of incandescent charcoal let fall into the tube will float upon
the surface of the monoxide, and burn with great brilliancy,
FIG. 62.
notwithstanding the intense cold
by which it is surrounded, as evi-
denced by the freezing of the
mercury (Fig. 62).
Water dissolves about its own
volume of nitrogen monoxide at
ordinary temperatures.
A taper which has been extin-
guished, but still bears a spark
of fire, is relighted, and burns
brilliantly when plunged into a
jar of nitrous oxide (Fig. 63).
In the same manner, the combustion of sulphur and phos-

FIG. 63.
phorus is effected with great
energy in an atmosphere of
this gas.
Equal volumes of nitrous
oxide and hydrogen form a
mixture which explodes on
the passage of an electric
spark or on the application
of flame.

N2O + H² =
2
2
H2O + N²
2
2
volumes. volumes. volumes. volumes.
Respiration is a slow com-
bustion and may be sustained
for a few seconds by nitrogen
monoxide. Such inhalation
does not suffocate but it dis-
turbs the functions of the
nervous system, producing
anæsthesia, and for this pur-
pose nitrous oxide is now largely employed by surgeons and
dentists. The insensibility is frequently preceded by a stage.
of intoxication, hence the name laughing-gas, which was given
by Davy.
It must be added that these exhilarating effects have not
been observed in recent experiments upon perfectly pure nitro-
gen monoxide.
NITROGEN DIOXIDE, OR NITRIC OXIDE.
153
NITROGEN DIOXIDE, OR NITRIC OXIDE.
Density compared to air
Density compared to hydrogen.
Molecular weight NO
1.039
15.
30.
Preparation. This gas was discovered in 1772 by Hales;
it is prepared by decomposing cold, dilute nitric acid by metallic
copper.
3Cu + 8HNO³
Copper. Nitric acid.
3Cu(NO³)² + 4H2O + 2NO
Cupric nitrate.
The copper and water are introduced into a gas-bottle, and
ordinary nitric acid is added by means of a funnel-tube; the
copper is immediately attacked and dissolved, forming cupric
nitrate (Fig. 64), and at the same time nitric oxide gas is dis-
engaged. This gas absorbs oxygen from the air and is con-

FIG. 64.
verted into red vapors, which are at first apparent in the gas-
bottle, but as the evolution of nitric oxide continues, the gas
in the flask gradually becomes colorless, and may then be col-
lected in jars over water.
Properties. Nitric oxide is a colorless gas. It has recently
been liquefied by Cailletet. It is decomposable by heat, but
less easily than the monoxide. It is scarcely soluble in water,
which only takes up a twentieth of its volume. Its most charac-
teristic property is the energy with which it absorbs half its
volume of oxygen, passing into the state of nitrogen peroxide
or red vapors.
G*
154
ELEMENTS OF MODERN CHEMISTRY.
If a jar filled with nitric oxide be opened to the air, the red
vapors appear at once.
2NO + 0²
N2O4
Nitric oxide supports the combustion of certain substances.
Phosphorus burns in it brilliantly, but the gas does not, like
oxygen and nitrogen monoxide, relight a taper still presenting
a spark.
Hydrogen decomposes nitric oxide at a temperature but
slightly elevated, forming water and nitrogen.
NO + H2 N+ H2O
The mixture of the two gases in equal volumes takes fire on
the application of flame.
If a few drops of carbon disulphide be poured into a jar of
nitric oxide, the vapor of the volatile liquid is at once diffused
throughout the gas, and on the approach of a lighted taper a
brilliant flash of light is produced, the sulphur and carbon being
burned by the oxygen of the nitric oxide.
The light produced by this combustion determines at once,
and like the solar light, the combination of chlorine and hydro-
gen.
When a mixture of nitric oxide with an excess of hydrogen
is passed through a heated tube containing platinum sponge,
water and ammonia are formed.
NO + 5H H2O + NH3
Under other circumstances hydroxylamine may be produced.
A solution of ferrous sulphate absorbs nitric oxide with
avidity, assuming a dark-brown color; this is a characteristic
property, by which nitric oxide may be recognized.
NITROGEN TRIOXIDE.
N203
This compound is formed when a mixture of nitric oxide
with a large excess of oxygen is subjected to intense cold. It
is also formed, together with nitric acid, when nitrogen perox-
ide is treated with a small quantity of cold water.
2N²O¹ + H2O
Nitrogen peroxide.
2HNO3 + N2O³
Nitric acid.
It is a blue liquid, which boils at a low temperature.
NITROGEN PEROXIDE.
155
NITROGEN PEROXIDE.
NO² or N2O4
Preparation. When well dried lead nitrate is heated to
redness it is decomposed into lead oxide and nitrogen peroxide,
which may be condensed in a well-cooled receiver.
Pb(NO3)2
Lead uitrate.
РЬО
Lead oxide.
+ 0 + N²O¹
The first portions of nitrogen peroxide that are condensed
generally retain a trace of moisture, and present a green color;
if the receiver be then changed, there collects a yellow liquid
which solidifies to a crystalline mass at —10°.
Properties.-Nitrogen peroxide is a mobile liquid, almost
colorless at very low temperatures; at 0° it has a somewhat
darker color, and at 15° it is orange-brown. It boils at 22°,
and its vapor is red. Near the point of ebullition its volu-
metric composition corresponds to the formula N2O*; that is,
two volumes of nitrogen and four volumes of oxygen are con-
densed into two volumes of N'O, and occupy the same space
as two atoms (one molecule) of hydrogen.
But at a higher temperature this vapor is dissociated; that
is, it is gradually decomposed in such a manner as to occupy
double its primitive volume. The two atoms of nitrogen and
four atoms of oxygen which constitute two volumes of N'O¹
at a low temperature, occupy four volumes at about 70°.
NO2
NO2
NO2 NO2
Red vapors at 20°.
Red vapors at 70°.
The vapor of nitrogen peroxide is very corrosive, and dan-
gerous to inhale.
A small quantity of cold water decomposes nitrogen perox
ide into nitrogen trioxide and nitric acid; a larger quantity of
water causes the formation of nitrous and nitric acids.
N²O¹ + H2O
HNO² + HNO³
Nitrous acid.
Nitric acid.
1
156
ELEMENTS OF MODERN CHEMISTRY.
When a mixture of nitrogen peroxide and hydrogen is passed
over heated platinum sponge, water and ammonia are formed.
Nitryl Chloride and Bromide.-Like nitric oxide, which
may be called nitrosyl, nitrogen peroxide may play the part of
a radical. There exists a chloride and also a bromide of nitro-
gen peroxide or nitryl.
NO CI
Nitryl chloride.
NO2Br
Nitryl bromide.
The latter compound is formed, together with other products,
when bromine acts upon nitrogen peroxide at a very low tem-
perature. The chloride of nitryl has recently been obtained.
by the reaction of phosphorus oxychloride upon silver nitrate.
POCP+
Phosphorus
oxychloride.
3AgNO3
Ag³PO +
3(NO²CI)
Nitryl chloride.
Silver nitrate. Silver phosphate.
Nitryl chloride is a light-yellow liquid, boiling at +5° and
solidifying at
31°.
In contact with water, it forms nitryl hydrate (nitric acid),
and hydrochloric acid.
NO²CI + H2O HCl + HNO³
In this reaction, the nitric acid is formed at the expense of
the water, of which one atom of hydrogen is removed by the
chlorine and replaced by the radical nitryl. Hence nitric acid
and water may be said to belong to the same type:
HOH
Water.
(NO2)OH
Nitric acid.
It is seen that in nitric acid the group NO2 replaces one
atom of hydrogen in water, this group is therefore monatomic.
But the atom of hydrogen in nitric acid may also be replaced
by another nitryl group, and the result is an oxide of nitryl,
the anhydride of nitric acid, or nitrogen pentoxide. The fol-
lowing formulæ will illustrate the relations between these com-
pounds and water which is their type:
}0
H
HS
Water.
NO2
0
H
Nitric acid.
(Nitryl hydrate)
NO2
NO2
}0
Nitrogen pentoxide.
(Nitryl oxide.)
NITROGEN PENTOXIDE-NITRIC ACID.
157
NITROGEN PENTOXIDE.
(NITRIC ANHYDRIDE.)
N205
This compound was obtained by H. Sainte-Claire Deville by
the action of chlorine upon dry silver nitrate heated to between
58 and 60°.
2AgNO3 + Cl2
Silver nitrate.
N2O5 + 2AgCl + 0
Nitrogen pentoxide. Silver chloride.
It may also be obtained by passing the vapor of nitryl chlo-
ride over silver nitrate heated to 70°.
AgO.NO² + NO CI
Silver nitrate.
Nitryl chloride.
AgCl + (NO²) O.
Nitrogen pentoxide.
Also, as shown by Berthelot, by the action of phosphorus
pentoxide upon concentrated nitric acid.
2HNO3 H2O N2O5
Nitrogen pentoxide is solid and crystallizes in right-rhombic
prisms. It melts at 29.5°, and boils between 48 and 50°. It
is very unstable and explodes spontaneously even when it is
preserved at a low temperature.
NITRIC ACID.
HNO3
The atmosphere frequently contains a trace of nitric acid
vapor or other compounds of nitrogen and oxygen, and small
quantities of ammonium nitrate and nitrite may be detected in
rain-water. After passing a current of air for a long time
through a solution of potassium carbonate, the liquid is found
to contain potassium nitrate (Cloez). It may be admitted that
the compounds of nitrogen and oxygen are formed directly by
the action of electricity upon the elements of the air.
The nitrates of potassium, sodium, magnesium, and calcium
are met with in certain soils, often in abundance. They are
formed wherever nitrogenized organic matters decompose in
contact with the air and in presence of porous matters and
alkaline bases. Under these circumstances, the ammonia re-
sulting from the decomposition is oxidized to nitric acid.
The experiments of Cloez have shown that the elements of
14
158
ELEMENTS OF MODERN CHEMISTRY.
the air may unite directly, forming nitrates in the soil, wherever
alkaline bases and oxidizable matters are present.
Preparation. Nitric acid is obtained by decomposing an
alkaline nitrate with sulphuric acid. In the laboratory, the
operation may be conducted in a glass retort, the neck of which
passes, without cork, into a cooled receiver. 98 parts of con-
centrated sulphuric acid and 85 parts of sodium nitrate are
employed. On the application of heat, nitric acid is vola-
tilized, mixed at the commencement of the operation with red
vapors. The acid condenses in the receiver as a yellow liquid,
fuming in the air. Sodium acid sulphate remains in the retort.
H2SO¹ +
+
NaNO3
Na
H
}
SO +
+ HNO³
Sodium nitrate. Sodium acid sulphate.
In the arts, the sodium nitrate is decomposed with a less
concentrated sulphuric acid, the decomposition of the nitric
acid during the operation being thus avoided. The operation
is conducted in cast-iron retorts, A (Fig. 65), the lateral tubes
of which, B, are adapted to stoneware tubes communicating

Plano redko «YNGUNAN
Pq
B
D
FIG. 65.
with a series of stoneware bottles, D, where the acid con-
denses. The temperature is elevated towards the close of the
operation, and sodium neutral sulphate is formed.
H2SO4 + 2NaNO³ = Na²SO¹ + 2HNO³
NITRIC ACID.
159
Properties. When perfectly pure, nitric acid is colorless,
but it rapidly becomes yellow under the influence of light,
undergoing a partial decomposition. When exposed to the
air, it gives off abundant white fumes. Its density is 1.52; it
solidifies at --49°, and boils at 86°.
When its vapor is passed through a red-hot porcelain tube,
it is decomposed into nitrogen peroxide, oxygen, and water.
2HNO3 H2O + N²O¹ + 0
The mixture of nitric acid with water produces an elevation
of temperature. The dilute acid, formed by mixing 42.8 parts
of water and 100 parts of the concentrated acid, is a colorless
liquid, boiling constantly at 123°; yet it cannot be considered
as a definite compound (Roscoe).
Nitric acid readily gives up a portion of its oxygen to bodies
having an affinity for that clement. It energetically oxidizes
sulphur, phosphorus, arsenic, iodine, silicon, carbon, and most
of the metals.
If nitric acid be poured upon red-hot charcoal, the combus-
tion is vividly intensified by the decomposition of the nitric
acid, and red fumes appear at the same time.
Copper decomposes nitric acid with an abundant disengage-
ment of nitric oxide, which is converted into nitrogen peroxide
by contact with the air.
Certain metals attack the dilute acid more readily than the
concentrated; iron is one of these metals.
If dilute nitric acid be poured upon clean iron wire, chemi-
cal action at once takes place, and there is an abundant evolu-
tion of red vapor; but if the same wire be plunged into the
concentrated acid, no action is manifested; and further, if the
strong acid be poured off and replaced by dilute acid, the latter
undergoes no decomposition; the iron has become passive by
becoming covered with a thin layer of gas. But if its surface
be touched with a copper wire, chemical action is at once re-
established between the iron and the nitric acid.
The action of tin upon nitric acid is worthy of notice. Tor-
rents of red vapor are disengaged, and the metal is converted
into a white powder, which is stannic acid. In this reaction
small quantities of ammonia and hydroxylamine are formed at
the expense of the elements of the nitric acid, and remain
combined with the excess of acid.
The conversion of nitric acid into ammonia may be more
160
ELEMENTS OF MODERN CHEMISTRY.
complete. If zinc be introduced into very dilute nitric acid,
the metal dissolves slowly and without disengagement of gas;
the liquid is then found to contain zinc nitrate and ammo-
nium nitrate. The nascent hydrogen set free from a portion
of the nitric acid by the zinc reduces another portion of the
acid, forming water and ammonia.
Zn + 2HNO³
Zinc.
2HNO + 4H
Zn(NO3)2 + H2
Zinc nitrate.
3H 0+ (NH)NO³
Ammonium nitrate.
Nitrogen dioxide decomposes nitric acid. When a current
of this gas is passed through nitric acid, the latter becomes
colored, according to its concentration, brown, yellow, or bluish-
green.
Under these circumstances the acid is reduced, and
either nitrogen peroxide or nitrous acid is formed and remains
dissolved in the liquid, the former communicating a brown,
the second a blue or green color.
Nitric acid is one of the most important acids; it is largely
used as a reagent. It is employed in the manufacture of sul-
phuric acid, and also to oxidize certain organic matters, such
as starch and sugar, which it converts into oxalic acid.
Nitro-hydrochloric Acid.-A mixture of nitric and hydro-
chloric acids is called nitro-hydrochloric or nitro-muriatic acid,
or aqua regiæ. This liquid dissolves gold and platinum, and
it owes this property to the chlorine, which is set at liberty by
the mutual action of the two acids.
2HCI + 2HNO³
2H2O + N2O4 + Cl²
When the mixture is left to itself it gradually assumes a
yellow color, undergoing a partial decomposition, as indicated
by the above formula; but this decomposition is limited, and
only complete in the presence of a metal capable of absorbing
the chlorine.
But the reaction between hydrochloric and nitric acids gives
rise to the formation of other products, noticed by Gay-Lussac
and Baudrimont; these are ternary compounds of oxygen, ni-
trogen, and chlorine. One is a red vapor, condensing at -7°
to an orange-red liquid. Its composition is probably expressed
by the formula NOCI².
It may be regarded as nitrogen peroxide in which one atom
of oxygen is replaced by an equivalent quantity, that is, two
atoms, of chlorine.
PHOSPHORUS.
161
The other is a gas which does not liquefy at very low tem-
peratures; it is nitrosyl chloride, NO.Cl. By reacting with
water it forms hydrochloric and nitrous acids.
NO.C1 + H2O = HCl + NO.OH
It will be noticed that nitrosyl chloride bears the same rela-
tion to nitrous acid that nitryl chloride bears to nitric acid.
The following formula will illustrate the constitution of these
bodies:
NO.CI
Nitrosyl chloride.
NO2.CI
Nitryl chloride.
NO
H
}
Nitrous acid.
NO2
H
}
NO
0
0
NO
Nitrogen trioxide.
0
}
Nitric acid.
NO2
NO2
O
Nitrogen pentoxide.
PHOSPHORUS
Vapor density compared to air
Vapor density compared to hydrogen
Atomic weight P
4.32
61.1
31.
Brandt, an alchemist of Hamburg, while attempting to ex-
tract the philosopher's stone from urine, discovered phosphorus
in 1669. But urine contains only a small quantity of phos-
phates and can yield but traces of phosphorus, so that this
body only became generally known to chemists after Gahn
demonstrated its existence in bones, and Scheele discovered the
process for its extraction.
The process of the latter chemist is still in use; it consists
in treating bone-ash with dilute sulphuric acid, by which means
the tricalcium phosphate of the bones is converted into mono-
calcium phosphate, ordinarily called acid phosphate of lime.
Ca³(PO¹)² + 2H²SO*
Tricalcium
phosphate.
CaH¹(PO)² + 2CaSO¹
Calcium acid
phosphate.
Calcium
sulphate.
The latter phosphate being soluble is separated from the
calcium sulphate by filtration, and the solution is evaporated
and mixed with powdered charcoal. The mixture is dried and
gradually heated to redness in cast-iron vessels. By this means
the calcium acid phosphate is converted into calcium meta-
phosphate by the expulsion of two molecules of water.
2H2O + Ca(PO³)²
CaH (PO)2
Calcium acid phosphate.
Calcium metaphosphate.
14*
162
ELEMENTS OF MODERN CHEMISTRY.
The latter is strongly heated with charcoal in clay retorts
(Fig. 66), and is decomposed, yielding carbon monoxide and
phosphorus which distils over, and leaving a residue of calcium
pyrophosphate.
2Ca(PO³)² + 5C Ca²P²0 + 5CO + P²
Calcium
metaphosphate.
Carbon
Calcium
pyrophosphate. monoxide.
The phosphorus condenses in the water in the receiver A,
in which the neck of the retort C is engaged.

EEB
FIG. 66.
As it is impossible to expel all of the water from the calcium
acid phosphate, this water is decomposed by the charcoal, hy-
drogen and carbon monoxide being formed, together with a
small quantity of phosphoretted hydrogen.
100 kilogrammes of bone yield between 8 and 9 kilo-
grammes of phosphorus. The latter is purified by enclosing
it in a chamois-skin sack, and strongly compressing it under
water at 50°; the phosphorus passes through the leather and
collects under the water. It is moulded into sticks by being
drawn up into slightly conical glass tubes, which are then
plunged into cold water. The phosphorus solidifies and is
easily drawn from the tubes.
Physical Properties. Recently-fused phosphorus is trans-
parent, colorless, or having a pale-yellow tint, flexible, and soft
PHOSPHORUS.
163
き
​enough to be easily scratched by the nail. One-tenth per cent.
of sulphur renders it hard and brittle. It has a well-marked
odor, slightly resembling that of garlic. Its density at 10° is
1.83. It melts at 44° and boils at 290°; its vapor is colorless
and has a density of 4.32 compared to air, or 61.1 compared
to hydrogen.
If one volume of hydrogen weighs 1, one volume of vapor
of phosphorus weighs 61.1, and this number should represent
the weight of one atom of phosphorus; now it represents the
weight of two atoms, and the vapor of phosphorus presents
the singular anomaly that it contains in the same volume
twice as many atoms as the simple gases, such as hydrogen
or nitrogen. If one volume of hydrogen contain one atom,
one volume of phosphorus vapor contains two, and heat cannot
dissociate these two atoms in such a manner that they may
occupy two volumes instead of one. The vapor of arsenic
presents the same anomaly.
H
1 volume of
hydrogen.
N
1 volume of
nitrogen.
P2
1 volume of
phosphorus vapor.
As2
1 volume uf
arsenic vapor.
Phosphorus volatilizes below its boiling-point and even below
its melting-point. At ordinary temperatures it emits vapors in
a vacuum and even in the air. It is luminous in the dark,
from which property it derives its name, which signifies light-
bearer. The cause of this phenomenon is still obscure, but is
generally attributed to the slow oxidation which phosphorus
undergoes in the air.
When a stick of transparent phosphorus is kept under water,
it gradually becomes opaque and covered with a yellowish-white
pulverulent powder, while the central parts retain their trans-
parence. This white phosphorus is still pure, but the surface.
of the stick has divided into a multitude of little particles which
present a crystalline appearance. Some of them become de-
tached and remain suspended in the water, giving to the latter
the property of being luminous in the dark.
Phosphorus is rapidly dissolved by carbon disulphide and is
deposited in rhombic dodecahedra on the slow evaporation of
the solution.
There is an amorphous variety of phosphorus which differs
so much from ordinary phosphorus that it presents the prop-
164
ELEMENTS OF MODERN CHEMISTRY.
erties of an entirely different substance. It has a dark brown-
red color, and is not luminous in the dark. It is insoluble in
carbon disulphide; it does not melt and take fire like ordi-
nary phosphorus when heated to 50°. It is amorphous, and
presents a conchoidal fracture. Its density is 2.14. Ordinary
phosphorus is one of the most dangerous poisons, but this red
body exerts no action upon the economy. At 260° amor-
phous phosphorus melts, is converted into ordinary phospho-
rus, and presents the properties of the latter substance on
cooling.
Amorphous phosphorus results from a physical change
brought about by the action of light or heat on the ordinary
variety. If a stick of phosphorus be exposed to direct sun-
light, its surface assumes a red color; or if it be maintained
for a long time at a temperature of 240°, it is entirely con-
verted into the amorphous variety.
This transformation is also accomplished by the influence of
certain chemical agents. If a small stick of ordinary phos-
phorus be introduced into a test-tube and a very minute por-
tion of iodine be allowed to fall upon it, the iodine unites with
the phosphorus with the production of light and heat. A trace
of phosphorus iodide is formed, and the remainder of the phos-
phorus is converted into a hard, black mass, which yields a red
powder; this is amorphous phosphorus (E. Kopp, Brodie).
Thus prepared, this body volatilizes like arsenic, without
melting, and can be distilled without alteration, condensing in
a black mass, which contains only traces of iodine.
Chemical Properties.-Ordinary phosphorus possesses a
strong affinity for oxygen. When exposed to the air it slowly
oxidizes, and the slow combustion, aided by the moisture of the
air, produces a mixture of phosphorous and phosphoric acids.
Schönbein has shown that the slow oxidation of phosphorus
is accompanied by the formation of small quantities of ozone
and hydrogen dioxide, and he asserts that animonium nitrite is
formed at the same time.
When heated in the air to a temperature of 60°, phosphorus
takes fire and burns, producing a bright light and white vapors
of phosphorus pentoxide. In pure oxygen the combustion is
accomplished with great brilliancy.
Phosphorus may be burned under warm water by passing a
current of oxygen through the melted element by means of a
tube drawn out to a point (Fig. 67); each bubble of oxygen
HYDROGEN PHOSPHIDE.
165
which comes in contact with the phosphorus produces a bright
flash.
Phosphorus takes fire spontaneously in an atmosphere of dry
chlorine, phosphorus pentachloride being produced.
Uses of Phosphorus.-This body is principally employed in
the manufacture of matches. The inflammable tips of friction-
matches contain either ordinary or amorphous phosphorus. In
the first case, the phosphorus is mixed with inert substances,
such as sand or ochre, held together by strong glue; in the

FIG. 67.
second case, the ignition of the amorphous phosphorus, which
is but slightly combustible, is determined by potassium chlorate,
to which is also added antimony sulphide. All of these sub-
stances are made into a paste, into which the ends of the
matches are dipped. Sometimes the match-sticks are tipped
with a paste composed of potassium chlorate and antimony
sulphide, a mixture which only takes fire by friction upon a
prepared surface, composed generally of amorphous phosphorus
and antimony sulphide. All of these mixtures are held to-
gether by strong glue.
HYDROGEN PHOSPHIDE.
Density compared to air
Density compared to hydrogen
Molecular weight PH³
•
1.134
17.
34.
This gas was discovered by Gengembre in 1783.
When phosphorus is heated with a solution of caustic potassa,
there is a gas disengaged, which inflames spontaneously on con-
tact with the air; this is hydrogen phosphide. It is formed
according to the following equation:
3KOH + 4P + 3H20
Potassium hydrate.
3KH2PO² + PH³
Potassium hypophosphite.
166
ELEMENTS OF MODERN CHEMISTRY.
Preparation.—1. Hydrogen phosphide may be prepared by
heating phosphorus with a strong solution of potassium hydrate,
or with thick milk of lime, with which the flask (Fig. 68)

FIG. 68.
should be almost entirely filled. The gas is conducted under
the surface of water, and as each bubble arrives in contact with
the air it takes fire spontaneously, producing a bright flash and
a wreath of white smoke, which enlarges as it rises in the air.
2. The same spontaneously inflammable gas is evolved when
calcium phosphide is thrown into water (Fig. 69). The phos-
phide of calcium is prepared by passing vapor of phosphorus
over fragments of incandescent lime; it instantly decomposes
water with formation of calcium hypophosphite and sponta-
neously inflammable hydrogen phosphide.
However, when calcium phosphide is treated with hydro-
chloric acid, hydrogen phosphide is produced, which does not
take fire without the application of heat (Fig. 70).
In this case, the gas is formed by double decomposition
between the hydrochloric acid and the calcium phosphide; the
calcium combines with the chlorine, forming calcium chloride,
and the hydrogen of the acid combines with the phosphorus.
3. In the same manner, when phosphorous acid is strongly
heated in a small retort, it evolves a hydrogen phosphide which
is not spontaneously inflammable.
4H³PO³
Phosphorous acid.
PH³ +
3H³PO¹
Phosphoric acid.
COMPOUNDS OF PHOSPHORUS AND CIILORINE.
167
Properties. The gas thus obtained is colorless, and pos-
sesses a garlicky odor. It is but slightly soluble in water, but
is soluble in alcohol and in ether. When it is pure it does not
take fire in the air at a temperature below 100°, and then
burns with a very luminous white flame. According to Paul
Thenard, the spontaneous inflammability of the hydrogen phos-
phide prepared by the methods first mentioned is due to the


FIG. 69.
FIG. 70.
presence of another phosphide, PH; this is a very volatile
liquid, extremely inflammable, and the least trace of its vapor
in hydrogen phosphide gas communicates to the latter the
property of spontaneous inflammability.
Hydrogen phosphide is absorbed by a solution of cupric
sulphate, with the formation of black phosphide of copper.
The composition of hydrogen phosphide, PH³, recalls that
of ammonia, NH³, and the analogy between the two gases is
further revealed by the property common to both of uniting
with hydriodic acid. There is a compound of hydrogen phos-
phide with hydriodic acid, a well-defined, solid body, crystal-
lizing in brilliant cubes.
PHI³.III or PHI phosphonium iodide.
The existence of a solid phosphide of hydrogen has been
demonstrated, and the formula PH attributed to it.
COMPOUNDS OF PHOSPHORUS AND CHLORINE.
There are two chlorides of phosphorus :
Phosphorus trichloride
Phosphorus pentachloride
PC13
PC15
168
ELEMENTS OF MODERN CHEMISTRY.
There are, besides,
Phosphorus oxychloride
Phosphorus sulphochloride
POCIS
PSC13
PHOSPHORUS TRICHLORIDE.
PC13
When a current of dry chlorine is passed over phosphorus
heated in a small tubulated retort, a liquid compound of chlo-
rine and phosphorus is formed and may be condensed in a
cooled receiver. This is phosphorus trichloride. It is a
fuming, colorless liquid, having a density of 1.45 and boiling
at 74°.
If it be poured into water, it at first sinks to the bottom,
and then rapidly disappears, evolving white fumes of hydro-
chloric acid, and forming phosphorous acid, which remains in
solution.
PCP³ + 3H20 H3PO3 + 3HСІ
PHOSPHORUS PENTACHLORIDE.
PC15
In contact with an excess of chlorine, phosphorus trichloride
absorbs two more atoms of that gas, and condenses into a yellow
crystalline solid, phosphorus pentachloride.
This body is volatile, and sublimes without fusion when
heated, even below 100°. When heated under pressure, it
melts at 148° and boils at a slightly higher temperature. Its
vapor density, taken at 336° and reduced to 0°, is equal to
3.656. This density should be double, supposing that the
molecule PC15 occupies two volumes. The anomaly, however,
is only apparent, for there are good reasons for believing that
at the temperature 336° the vapor of phosphorus pentachloride
no longer exists, and that the compound is decomposed or dis-
sociated into a mixture of phosphorus trichloride and chlorine,
a mixture which would give four volumes of vapor for one
molecule of PC15.
>
PC15
{
S PC13
2 volumes.
C12
2 volumes.
4 volumes.
Indeed, when the vapor density of phosphorus pentachloride
is taken by diffusing it in the vapor of the protochloride, which
PHOSPHORUS OXYCHLORIDE.
169
prevents the dissociation before mentioned, a figure is found
which corresponds very nearly with the theoretic density 7.21
(A. Wurtz).
Phosphorus pentachloride decomposes water with energy,
forming hydrochloric and phosphoric acids.
PC¹³ + 4H²0 = H³PO¹ + 5HCl
When only a small quantity of water is present, hydrochloric
acid is disengaged, by the exchange of two atoms of chlorine
for one atom of oxygen, and a colorless liquid is formed which
is called phosphorus oxychloride. When heated in a current
of hydrogen sulphide, phosphorus pentachloride is converted
into the sulphochloride, a colorless liquid boiling at 126°.
POCI³
2HCl +
PSCF3
PC15+ H2O = 2HCl +
PC15+ H2S
PHOSPHORUS OXYCHLORIDE.
POCI3
This body is readily obtained by exposing phosphorus penta-
chloride to moist air until it becomes liquid, and subsequently
distilling the liquid (A. Wurtz). It is formed in a great num-
ber of reactions when phosphorus pentachloride is heated with
hydrated acids, such as oxalic acid, boric acid, etc., or with
oxides, such as phosphoric oxide. In these cases, one atom of
oxygen from the oxidized body is exchanged for two atoms of
chlorine from the pentachloride (Gerhardt).
Phosphorus oxychloride is a colorless liquid, boiling at 110°.
When poured into water, it sinks and is at once decomposed,
hydrochloric and phosphoric acids being formed.
H³
POCK +
03
H³ (
3
PO
H³
3
}
0³ + 3HCI
Phosphorus oxychloride. 3 molecules water. Phosphoric acid.
COMPOUNDS OF PHOSPHORUS WITH BROMINE
AND IODINE.
Two bromides of phosphorus are known:
Phosphorus tribromide, PBr, a colorless liquid.
Phosphorus pentabromide, PBr, a yellow, crystalline mass.
To the trichloride and tribromide of phosphorus there cor-
responds a triiodide, concerning which but little is known.
H
15
170
ELEMENTS OF MODERN CHEMISTRY.
The best defined and most important combination of phos-
phorus with iodine is the compound PI.
Phosphorus Iodide, P2I.-This body is obtained by dis-
solving 26 parts of dry phosphorus in 30 or 40 times its weight
of carbon disulphide, and gradually adding to the solution 203.4
parts of iodine. The liquor, at first reddish-yellow, becomes
orange-yellow; it is distilled on the water-bath to drive out a
part of the carbon disulphide, and on cooling it deposits a
bright-red, crystalline mass. This is the iodide P²I.
It crystallizes in long, brilliant, flattened needles, which are
flexible, and melt at 100°. On contact with water it is decom-
posed, forming phosphorous and hydriodic acids, and at the
same time depositing a yellow, flocculent precipitate rich in
phosphorus (Corenwinder).
COMPOUNDS OF PHOSPHORUS AND OXYGEN.
Phosphorus combines with oxygen, forming two oxides:
Phosphorus trioxide, or phosphorous oxide
Phosphorus pentoxide, or phosphoric oxide
P203
P205
Each of these oxides can combine with three molecules of
water, phosphorous and phosphoric acids being thus formed.
P²O³ + 3H20
2H PO³
2H PO
P205 + 3H20
Besides these two acids there is another containing less oxy-
gen; it is hypophosphorous acid, whose corresponding oxide is
unknown. These three acids form a series containing for three
atoms of hydrogen and one atom of phosphorus regularly-in-
creasing quantities of oxygen; they may be said to constitute
different degrees of oxidation of hydrogen phosphide.
PH³ hydrogen phosphide.
PH³O (missing).
PH3O2 hypophosphorous acid.
PHO³ phosphorous acid.
PHO¹ phosphoric acid.
Constitution of the Oxygen Acids of Phosphorus.—Phos-
phorous and phosphoric acids are related, the first to phos-
phorus trichloride, the second to phosphorus oxychloride. In
HYPOPHOSPHOROUS ACID.
171
fact, they are derived from these compounds by the action of
water.
P""Cl3 phosphorus trichloride.
P(OH)3 phosphorous acid (phosphorus trihydrate).
(PO)""Cl³ phosphorus oxychloride (phosphoryl trichloride).
(PO)""(OH)³ phosphoric acid (phosphoryl trihydrate).
To phosphorus pentachloride, PC15, would correspond a pen-
tahydrate, P(OH)5, which is unknown. Phosphoric acid would
be derived from the latter by the loss of a molecule of water.
P(OH)5 =H2O+ (PO)(OH)3
It is seen that in phosphorous acid, as in the trichloride, phos-
phorus is regarded as playing the part of a triatomic element,
while it is pentatomic in the pentachloride.
In hypophosphorous acid, it must be admitted that one atom
of hydrogen is united directly to the triatomic phosphorus, and
its constitution is expressed by the formula
PSH
OH
HYPOPHOSPHOROUS ACID.
H³PO2
When phosphorus is boiled with milk of lime or with a con-
centrated solution of baryta, a soluble hypophosphite is pro-
duced, and on treating the solution of barium hypophosphite
with sulphuric acid, a precipitate of barium sulphate and a
solution of hypophosphorous acid are obtained; they may be
separated by filtration. When sufficiently concentrated, the
liquor leaves a colorless and very acid syrupy residue, which
constitutes hypophosphorous acid.
This acid is decomposed at a high temperature, yielding
phosphoric acid and hydrogen phosphide. It is gifted with
energetic reducing properties: it instantly decomposes the salts
of mercury and silver, setting free the metal. An excess of
hypophosphorous acid added to a solution of cupric sulphate
precipitates, by the aid of a gentle heat, hydride of copper,
Cu H, which is decomposed at 100° into copper and hydrogen
(A. Wurtz).
172
ELEMENTS OF MODERN CHEMISTRY,
Hypophosphorous acid contains three atoms of hydrogen,
only one of which is capable of being replaced by an equiva-
lent quantity of a metal. The composition of the hypophos-
phites is consequently expressed by the following general
formula:
R'H2PO2
in which R' represents a monatomic metal, such as potassium,
capable of replacing hydrogen atom for atom.
PHOSPHOROUS ACID.
H3PO³
Preparation.-Phosphorous acid results from the action of
water upon phosphorus trichloride, as already seen.
It may
be obtained in a state of purity by evaporating the acid liquor
resulting from this reaction, and heating the syrupy residue
in a platinum capsule until the odor of hydrogen phosphide.
is perceptible. On cooling, the acid solidifies to a crystalline
mass.
Properties. These crystals absorb moisture when exposed
to the air, and are resolved into an intensely acid liquid; they
melt at a gentle heat, and are decomposed by a high tempera-
ture into hydrogen phosphide and phosphoric acid.
Like hypophosphorous acid, phosphorous acid possesses re-
ducing properties.
Its boiling aqueous solution reduces the salts of mercury,
silver, and gold, and this reduction is favored by the presence
of ammonia. It converts arsenic acid into arsenious acid.
Chlorine, bromine, and iodine convert it into phosphoric acid
in presence of water.
H³PO³ + H2O + Cl² 2HCl + H³PO*
Phosphorous acid contains three atoms of hydrogen, two of
which are replaceable by an equivalent quantity of a metal.
It is hence called a dibasic acid.
The composition of the neutral hypophosphites is expressed
by the general formula
R2 HPO³,
in which R' represents a monatomic metal like potassium or
sodium.
PHOSPHORIC OXIDE-PHOSPHORIC ACID.
173
PHOSPHORIC OXIDE, OR PHOSPHORUS
PENTOXIDE.
(PHOSPHORIC ANHYDRIDE.)
P205
This compound may be obtained by burning phosphorus in
a large globe filled with dry air. A dense white smoke is pro-
duced, and condenses upon the walls of the vessel in flakes like
snow. This body is the anhydride of phosphoric acid. When
exposed to the air, it absorbs moisture and is converted into
metaphosphoric acid.
P²О5 + H2O = 2HPO³
When thrown into water it dissolves with a hissing noise,
such as is produced by a red-hot iron.
Phosphoric acid volatilizes at a dull-red heat; it is undecom-
posable by heat. It yields the oxychloride when distilled with
phosphorus pentachloride.
P205 + 3PC15
5POC13
It also yields phosphorus oxychloride when distilled with
dry common salt (Lautemann).
PHOSPHORIC ACID.
(ORTHOPHOSPHORIC ACID.)
H3PO4
Preparation.-1. This acid may be prepared by boiling
phosphorus with nitric acid. On account of the violence of
the reaction the operation is difficult to regulate, and even
dangerous when ordinary phosphorus is employed, but it
succeeds very well with powdered amorphous phosphorus.
This is heated with tolerably concentrated nitric acid in a
retort, fitted with a receiver, and, when the whole of the phos-
phorus has disappeared, a little nitric acid is added to the
contents of the retort, and the liquid is concentrated in a
platinum capsule. When the last portions of nitric acid have
been driven out, a small quantity of water is added, and the
syrupy liquid is placed in a bell-jar over a dish containing
concentrated sulphuric acid. At the end of some time, the
15*
174
ELEMENTS OF MODERN CHEMISTRY.
phosphoric acid is deposited in the form of hard, transparent,
prismatic crystals.
2. A current of chlorine may be passed through warm water
under which is a layer of melted phosphorus. Phosphoric
acid and hydrochloric acid are formed.
PC15 + 4H²0
H³PO+5HCI
As soon as all of the phosphorus has disappeared the solution
is evaporated, and the hydrochloric acid is driven out by
heating the residue to 200°. The residue is dissolved in water
and forms a solution which will deposit the acid in crystals
when concentrated as indicated above.
Properties. When exposed to the air, these crystals attract
moisture and deliquesce. Their solution is very acid. It does
not coagulate white of egg, and it produces no cloud in a solu-
tion of barium chloride, but it forms a white precipitate of
ammonio-magnesium phosphate in a solution of magnesium
sulphate on the addition of ammonia. With silver nitrate to
which ammonia has been added, it gives a yellow precipitate
of trisilver phosphate, Ag³PO. Orthophosphoric acid contains
three atoms of hydrogen, each of which is replaceable by an
equivalent quantity of metal.
PYROPHOSPHORIC ACID.
H&P207
When orthophosphoric acid is heated for a long time to
213° it loses water and is converted into a new acid, which is
called pyrophosphoric. Two molecules of phosphoric acid lose
one molecule of water, and then unite to form a single mole-
cule of pyrophosphoric acid.
OH
PO OH
OH
OH
H2O +
OH
PO OH
O
PO-OH
H¹P2O7
PO OH
OH
OH
The residue constitutes an opaque, semi-crystalline mass,
composed almost entirely of pyrophosphoric acid.
METAPHOSPHORIC ACID.
175
Its aqueous solution forms a white precipitate of silver
pyrophosphate in solutions of silver nitrate.
H¹PO + 4AgNO
Ag¹PO + 4HNO
When heated with water, pyrophosphoric acid again com-
bines with one molecule of that liquid, and is converted into
phosphoric acid by a reaction the inverse of that by which it
is formed.
METAPHOSPHORIC ACID.
HPO3
Preparation. When phosphoric acid is heated to redness
in a platinum crucible, a hard, transparent, vitreous mass is
obtained on cooling; this is metaphosphoric acid.
It is formed by the abstraction of one molecule of water
from phosphoric acid.
H³PO H2O HPO3
It may also be obtained directly from calcium acid phos-
phate, the preparation of which from bone-ash has already been
described. A slight excess of dilute sulphuric acid is added
to the concentrated solution of this salt, and the insoluble cal-
cium sulphate formed is separated by filtration. Since, how-
ever, the calcium sulphate is not entirely insoluble in water,
the solution is concentrated, and alcohol added, which com-
pletely precipitates the sulphate. The liquid is again filtered,
the alcohol driven off by evaporation, and the residue heated
to a temperature near redness to remove the excess of sulphuric
acid.
On cooling, a vitreous mass of metaphosphoric acid is ob-
tained.
An aqueous solution of metaphosphoric acid instantly pro-
duces a precipitate of silver metaphosphate in a solution of
silver nitrate.
HPO³ + AgNO3 AgPO3 + HNO3
A few drops of the acid solution added to white of egg sus-
pended in water produces an abundant white precipitate.
The same metaphosphoric acid is formed when phosphoric
oxide is thrown into a large quantity of cold water, or when it
is allowed to deliquesce in the air. Under these circumstances,
176
ELEMENTS OF MODERN CHEMISTRY.
one molecule of phosphoric oxide combines with only one
molecule of water.
P²О³ + H²O 2HPO³
The preceding considerations establish the existence of three
phosphoric acids, which differ both in composition and proper-
ties. To these three acids correspond three salts of silver, and
it will be seen that the latter differ from the acids only by
containing silver instead of hydrogen, a substitution which
takes place atom for atom.
ACIDS.
H3PO4 phosphoric acid (orthophos-
phoric).
H+P207 pyrophosphoric acid.
HP03 metaphosphoric acid.
SILVER SALTS.
Ag3PO trisilver phosphate (ortho-
phosphate).
Ag P20 silver pyrophosphate.
AgPO3 silver metaphosphate.
It may be added that, independently of the acids and salts
of which the composition and nomenclature have just been
considered, others have been described, the most interesting
of which are related to the metaphosphates, of which they con-
stitute polymeric modifications. That is, two, three, four, or
more molecules of metaphosphoric acid are condensed in a
single molecule, forming more complicated acids.
COMPOUNDS OF PHOSPHORUS AND SULPHUR.
When phosphorus is heated with dry sulphur, or when a
mixture of the two bodies is melted under water, they combine
with a vivid combustion which is sometimes accompanied by
dangerous explosions. The action is less violent with amor-
phous phosphorus. According to the proportions of these
bodies which are brought into contact, several combinations of
phosphorus and sulphur may be obtained, among which the
trisulphide, PS3, and the pentasulphide, P2S5, correspond to
phosphorous and phosphoric oxides. The pentasulphide may
be obtained in pale yellow crystals.
ARSENIC.
Vapor density compared to air
•
Vapor density compared to hydrogen
Atomic weight As.
10.37
150.
75.
Arsenic was discovered by A. Schroeder in 1694.
Natural State and Extraction.-There exists in nature a
ARSENIC.
177
common and abundant mineral which contains iron, sulphur,
and arsenic, and which is called mispickel; it is a sulphar-
senide of iron. When it is strongly heated, the arsenic is
volatilized and a residue of iron sulphide remains.
FeSAs
FeS + As
Mispickel. Iron sulphide.
The operation is conducted on the large scale in earthenware
cylinders placed horizontally in a furnace. The arsenic sublimes
into sheet-iron pipes fitted to the open extremity of the cylin-
ders which extend beyond the furnace. The volatilization of
the arsenic is facilitated by the addition of a certain quantity
of metallic iron.
The arsenic of commerce may be purified by distilling it with
charcoal in a stoneware retort.
Properties. Recently-sublimed arsenic presents the appear-
ance of a steel-gray, crystalline mass, having a metallic lustre.
Its crystalline form is an acute rhombohedron. Its density is
about 5.7.
Arsenic volatilizes without melting at a temperature below
dull redness. Its vapor is colorless. When it is heated under
strong pressure it melts to a transparent liquid. On exposure
to the air it loses its lustre and assumes a black-gray color; in
this case its surface becomes covered with a thin layer of a
brown-black pulverulent substance, regarded by some chemists.
as a suboxide of arsenic.

Arsenic oxidizes when it is
heated in the air or in oxygen.
If a small quantity of arsenic
be thrown upon a red-hot coal,
white vapors are produced, and
an alliaceous odor is percep-
tible.
A fragment of arsenic may
be strongly heated in the hori-
zontal branch of a tube con-
taining oxygen (Fig. 71); the
metal takes fire and burns with
FIG. 71.
bluish flame, producing white vapors of arsenious oxide.
If arsenic be preserved from the air under a layer of water,
in which it is insoluble, it oxidizes slowly, in such a manner as
to form a small quantity of arsenious acid, which dissolves in
H*
178
ELEMENTS OF MODERN CHEMISTRY.
the water. This property explains the efficacy of powdered
arsenic (commercial cobalt) for poisoning flies.
If powdered arsenic be sprinkled into dry chlorine, each
particle burns with a bright flash. The combustion indicates
the energy of the combination. The arsenic unites with the
chlorine, being converted into the trichloride AsCl³. It also
combines directly with bromine, with iodine, and with sulphur.
HYDROGEN ARSENIDE, OR ARSENIURETTED
HYDROGEN.
Density compared to hydrogen
Molecular weight AsH³.
39.
78.
Preparation. This gas may be prepared by the action of
hydrochloric acid upon zinc arsenide.
Zn³As² + 6HCl
Zinc arsenide.
2AsH³ + 3ZnCl2
Zinc chloride.
It is a gas which must be handled with great prudence, as it
is extremely poisonous.
Properties. Hydrogen arsenide is colorless; its odor is
penetrating and garlicky. At a red heat it is decomposed
into arsenic and hydrogen. On the application of flame, it
burns in the air with a bluish light, producing fumes of
arsenious oxide. If the supply of air be insufficient, arsenic
is deposited. With one and a half times its volume of oxygen,
hydrogen arsenide forms an explosive mixture, the products of
the combination being water and arsenious oxide.
2AsH³ + 06 As¹0³ + 3H20
Chlorine decomposes hydrogen arsenide with a production
of light and the formation of hydrochloric acid. If an excess
of chlorine be present arsenic trichloride is formed, but if the
experiment be made in the presence of water, it is arsenious
oxide which is formed.
2A$H³ + 6C¹² + 3H²O
As²0³ + 12HCI
Water dissolves about one-fifth of its volume of hydrogen
arsenide. When this gas is agitated with a solution of cupric
sulphate, it disappears entirely if the gas be pure, and leaves
a residue of hydrogen should that gas have been present in
the free state in the mixture (Dumas).
3CuSO4 + 2AsH³
Cupric sulphate.
Cu³As² + 3H2SO¹
Copper arsenide.
ARSENIC CHLORIDE.- -ARSENIOUS OXIDE.
179
ARSENIC CHLORIDE.
AsC13
Preparation.-1. A current of dry chlorine may be passed
over powdered arsenic contained in a retort, the neck of which
fitted to a cooled receiver. The chloride formed condenses
as a yellow liquid, containing an excess of chlorine, from which
it may be freed by distillation over powdered arsenic (Dumas).
2. A mixture of 40 grammes of arsenious oxide and 400
grammes of sulphuric acid is gently heated in a tubulated
retort, and fragments of fused sodium chloride are gradually
added; arsenic chloride distils over and condenses in the
receiver.
3H2SO4 + 6NaCl + As²O³
Sodium chloride.
3Na²SO¹ + 2AsCl³ + 3H²0
Sodium sulphate.
Properties.—Arsenic chloride is a colorless, oily, and very
dense liquid. It boils at 134°. Its density at 0° is 2.05. It
gives off white fumes in the air, and is very poisonous.
An excess of water instantly decomposes it into hydrochloric
acid and arsenious oxide, which, being but slightly soluble, is
precipitated.
2AsC¹³ + 3H2O As²0³ + 6HCI
ARSENIOUS OXIDE.
As203
Preparation. This dangerous poison is obtained in the
arts by roasting arseniferous minerals, particularly mispickel.
Roasting is an operation which consists in heating a mineral
in contact with air, by which the oxidizable elements present
are oxidized. When arseniferous minerals are roasted, arsen-
ious oxide is formed among other products, and volatilizes, and
is condensed either in wide horizontal chimneys or in a large
building divided into numerous communicating compartments,
through which the vapor is led consecutively. It is collected
in the form of a powder, and is resublimed in cast-iron pots
surmounted by sheet-iron cylinders, in which it condenses.
Properties. Recently-sublimed arsenious oxide occurs as
vitreous masses; but it soon loses its transparency and becomes
milk-white, presenting the appearance of porcelain. When a
large piece of the opaque oxide is broken, the interior is usually
found to be still transparent and vitreous.
180
ELEMENTS OF MODERN CHEMISTRY.
Arsenious oxide then exists in two forms: the vitreous
variety is amorphous; the opaque is crystalline. The former
variety changes into the latter by a molecular transformation
which takes place in the midst of the amorphous vitreous mass.
Arsenious oxide crystallizes in regular octahedra or in tetra-
hedra; sometimes, but more rarely, in right-rhombic prisms.
It is dimorphous.
It dissolves slowly in cold water, in which it is but slightly
soluble, and in this respect there is a curious difference between
the opaque and the vitreous varieties. The latter is three times
more soluble than the former; while one part of the vitreous
oxide dissolves in 25 parts of water at 13°, one part of the
opaque variety requires 80 parts of water for its solution at the
same temperature.
The aqueous solution of arsenious oxide feebly reddens blue
litmus. It is almost tasteless. It may be regarded as contain-
ing normal arsenious acid, H'AsO³, corresponding to normal
phosphorous acid, H³PO³; but this hydrate cannot be separated
from the solution. On evaporation, the oxide As¹0³ is always
deposited.
2H³AsO³ = As²0³ + 3H²0
The aqueous solution of arsenious oxide, neutralized with
ammonia, gives a green precipitate with solution of cupric sul-
phate; this is copper arsenite, or Scheele's green. With silver
nitrate it gives a canary-yellow precipitate of silver arsenite.
Arsenious oxide is more soluble in hydrochloric acid than in
water. If a slip of clean copper be introduced into this solu-
tion, it becomes covered with a steel-gray or black coating of
arsenic.
Reinsch's test for arsenic consists in boiling the suspected
substance with dilute hydrochloric acid and bright metallic
copper. The arsenic is deposited upon the copper, and by
carefully heating the latter in a small tube the arsenic vola-
tilizes and is converted into arsenious oxide, which condenses
in the crystalline form, easily recognizable by aid of a micro-
scope.
By the action of zinc the solution of As2O³ in hydrochloric
acid disengages hydrogen arsenide; the zine displaces the hy-
drogen of the hydrochloric acid, and, by the action of this
nascent hydrogen upon the arsenious oxide, water and hydro-
gen arsenide are formed.
As²0³ + 6H² = 3H2O + 2AsH³
ARSENIOUS OXIDE.
181
Marsh's Apparatus.-The reducing action of nascent hy-
drogen upon arsenious oxide is used for the detection of this
substance by the aid of Marsh's apparatus.
This consists of an apparatus for the generation of hydrogen
(Fig. 72); it contains pure zinc and dilute sulphuric acid, and the
hydrogen burns at the

drawn-out jet with an
almost colorless flame.
If, however, a few
drops of a solution of
arsenious oxide be in-
troduced by the fun-
nel-tube, the character
of the flame is at once
changed; it becomes
bluish, elongated, and
diffuses a white smoke,
and if a white porce-
lain surface be de-
pressed into it, large
spots of a brownish
color are produced.
These are composed
1194
FIG. 72.
of arsenic, which is set free in the interior of the flame by
the decomposition of the hydrogen arsenide by the heat.

B
FIG. 73.
Fig. 73 represents a more perfect form of Marsh's appa-
ratus. The hydrogen, mixed with the hydrogen arsenide, first
16
182
ELEMENTS OF MODERN CHEMISTRY.
traverses a tube, B, filled with cotton, designed to arrest the
small drops of liquid which may be carried with the gas; it
then passes through a narrow tube wrapped with metallic foil
and heated to redness in a tube-furnace. The hydrogen arsen-
ide is decomposed into hydrogen and arsenic, and the latter is
deposited as a brilliant black mirror in the cooler portion of
the tube.
Marsh's apparatus permits the detection of the least trace
of arsenious or arsenic acid in a liquid. It is of great value
in medico-legal researches, as arsenious oxide is a common and
dangerous poison.
ARSENIC ACID
H³ASO¹
Preparation. When arsenious oxide is heated with nitric
acid having a specific gravity of 1.35, red vapors are disen-
gaged and the oxide is oxidized into arsenic acid, which may
be obtained as a syrupy liquid by sufficient concentration.
When left for a long time in a cool place it deposits colorless
crystals, which constitute a hydrate 2H³AsO + H²O (E.
Kopp). These crystals are very deliquescent, and dissolve in
water with the production of cold. They melt at 100°, losing
their water of crystallization, and there remains a mass com-
posed of fine needles, which constitute the normal acid
H³AsO¹.
When heated for some time to a temperature between 140
and 180°, this acid loses water, and is converted into pyro-
arsenic acid, H⭑As²07.
2H³AsO¹
H2O =
H+As2O7
Between 200 and 206° another quantity of water is driven
out, and on cooling there remains a pasty, pearly mass, which
is metarsenic acid, HAsO³.
H³ASO¹
H2O =
HASO³
It will be noticed that in their modes of formation and in
their constitution, arsenic, pyro-arsenic and metarsenic acids are
analogous to the corresponding acids of phosphorus.
When metarsenic acid is heated to dull redness, it loses all
of its hydrogen in the form of water, and is converted into
arsenic oxide, As205.
2HASO³
H2O As205
COMPOUNDS OF SULPHUR AND ARSENIC.
183
At this temperature the oxide melts, and at a bright-red
heat it is decomposed into arsenious oxide and oxygen.
As205 As²0³ +02
When exposed to the air it absorbs moisture, but very slowly,
and even when treated with water it requires a certain time for
solution.
Ordinary arsenic acid, which may be called ortharsenic, is
very soluble in water; its solution strongly reddens blue litmus
and possesses a very acid taste. It is reduced by nascent hydro-
gen, like the solution of arsenious oxide. When neutralized
with ammonia, it forms a bluish-white precipitate with solution
of cupric sulphate, and a brick-red precipitate with silver
nitrate. Hydrogen sulphide produces no immediate precipitate.
A solution of sulphurous acid reduces arsenic acid to arse-
nious oxide, and then on the addition of hydrogen sulphide, a
yellow precipitate of arsenic sulphide, As S³, is formed.
COMPOUNDS OF SULPHUR AND ARSENIC.
Three sulphides of arsenic are known:
Arsenic disulphide, or realgar.
Arsenic trisulphide, or orpiment
Arsenic pentasulphide
•
A s2S2
A s2S3
As2S5
Arsenic Disulphide, As S.-This body occurs in nature in
the form of transparent red crystals, which belong to the type
of the oblique rhombic prism.
It is obtained as a red mass having a conchoidal fracture by
melting 75 parts of arsenic with 32 parts of sulphur. It is
fusible, and may be crystallized by slow cooling. When strongly
heated in closed vessels, it boils and distils without alteration,
but when heated in the air, it burns into arsenious and sulphur-
ous oxides. The alkaline sulphides and ammonium sulphide.
dissolve realgar, leaving a brown powder which has been con-
sidered as a subsulphide of arsenic. Boiling solution of potas-
sium hydrate also dissolves realgar, forming a mixture of
potassium arsenite and sulpharsenite; the latter is a soluble
compound of arsenic trisulphide and potassium sulphide; a
brown powder remains undissolved.
Arsenic Trisulphide, or Orpiment, As2S3.-When a solu-
tion of arsenious oxide is submitted to the action of hydrogen
184
ELEMENTS OF MODERN CHEMISTRY.
sulphide, the liquid assumes a yellow color without the forma-
tion of any precipitate, but if a drop of hydrochloric acid be
added, a yellow, flocculent precipitate of arsenic trisulphide is
formed at once.
As²О³ + 3H2S = As²S³ + 3H2O
The composition of arsenic trisulphide corresponds to that
of arsenious oxide, and is the same as that of the orpiment
found in nature.
It may also be obtained by fusing together arsenic and sul-
phur in the proper proportions, or even arsenious oxide and
sulphur; in the latter case, sulphurous oxide is disengaged,
and arsenic trisulphide sublimes. Thus prepared, orpiment
occurs as crystalline masses of a yellow color, bordering upon
orange, and a pearly aspect. Its density is 3.459. It is fusible
and volatile.
Arsenic trisulphide obtained by precipitation is insoluble in
cold water, and but slightly soluble in boiling water, but it is
very soluble in ammonia. By continued boiling with water, it
yields hydrogen sulphide and arsenious acid (de Clermont
and Frommel). It is also dissolved by solutions of the alka-
line sulphides with the formation of sulpharsenites, compounds.
of two sulphides, in which the alkaline sulphide plays the part
of a base and the arsenic trisulphide the part of an acid.
Orpiment also dissolves in solutions of the caustic alkalies with
the formation of an arsenite and a sulpharsenite.
Arsenic Pentasulphide, As S.-By the prolonged action
of hydrogen sulphide upon a solution of arsenic acid, a pale-
yellow precipitate is obtained, which is arsenic pentasulphide.
2H³AsO+5H'S As2S58H20
It corresponds to arsenic oxide.
As205
Arsenic oxide.
As2S5
Arsenic sulphide.
The alkaline sulphides dissolve it with the formation of
sulpharsenates. Among the latter there is one having the
composition K³AsS4, and which corresponds to the arsenate
K³ASO. It is formed by the following reaction:
As2S5+3K2S = 2(K³AsS')
The existence of arsenic pentasulphide has recently been
questioned, the precipitated body seeming to be a mixture of
trisulphide and sulphur (de Clermont and Frommel).
ANTIMONY.
185
ANTIMONY.
Sb
122
Antimony is generally classed with the metals. It indeed
possesses the lustre of a metal, and it conducts heat and elec-
tricity; but in a true chemical classification these physical
properties cannot overbalance the most striking chemical anal-
ogies. By its affinities, and by the nature and constitution of
its compounds, antimony must find a place by the side of
arsenic, which must itself be classed with phosphorus and
nitrogen.
Metallurgy of Antimony.-The most common ore of anti-
mony, which is a sulphide, was known to the ancients. The
metal is extracted from it by a very simple process. The sul-
phide is first separated by fusion from the earthy materials,
called gangue, with which it is associated; it is then roasted
or heated in contact with air. The sulphur is in great part
expelled in the form of sulphurous oxide gas, and the antimony
is converted into oxide, which still contains some undecom-
posed sulphide. The whole is then pulverized, and the pow-
der mixed with pulverized charcoal impregnated with sodium
hydrate. This mixture is calcined in crucibles, and the anti-
mony oxide and a portion of the sulphide is reduced by the
charcoal; sodium sulphide is also formed, and this dissolves a
portion of the antimony sulphide, forming a flux which floats
upon the molten antimony; after cooling, the latter is found
at the bottom of the crucible as a button, easy to separate from
the scoriæ.
By another process the antimony sulphide is fused with
metallic iron. Iron sulphide and antimony are formed, and
the latter collects at the bottom by reason of its greater
density.
Perfectly pure antimony is prepared in the laboratory by
reducing antimonous or antimonic oxide by charcoal.
Properties. Antimony is a brilliant white metal, having a
slightly bluish lustre; it is brittle, and has a laminated frac-
ture. Its density is 6.715. It melts at about 450°, and
sensibly vaporizes at a white heat.
Antimony may be crystallized by allowing large masses of
the fused metal to cool slowly, and decanting the liquid por-
tion. Small acute rhombohedra may be obtained in this
manner.
16*
186
ELEMENTS OF MODERN CHEMISTRY.
When heated in contact with air, antimony is converted
into antimonous oxide, Sb2O³.
If a fragment of antimony be introduced into a cavity
scraped in a piece of charcoal, and the flame of a blow-pipe be
directed upon it, it melts, becomes red-hot, and gives off white
fumes. If now the molten globule be allowed to fall, it
breaks up into a multitude of smaller globules on striking the
floor, and each particle rebounds into the air as a brilliant
spark, leaving behind it a train of smoke.
Powdered antimony projected into dry chlorine unites with
that element, producing a brilliant combustion.
HYDROGEN ANTIMONIDE.
There is a compound of hydrogen and antimony which has
not yet been obtained in the pure state, but which, according
to all probability, is the body SbH. Like its analogue, hy-
drogen arsenide, it is decomposed by heat; it can also be pre-
pared in Marsh's apparatus by the action of nascent hydrogen
upon a solution containing antimony, and when decomposed
by heat it forms metallic rings and mirrors, which it is of im-
portance to distinguish from those formed by arsenic. The
following differences are sufficient for this purpose:
The antimony rings are not displaced when heated in a
current of hydrogen; the arsenic rings are volatilized, and
condense in a cooler portion of the tube.
The spots and rings of antimony are not dissolved by a solu-
tion of sodium hypochlorite (Labarraque's solution), which at
once dissolves those of arsenic.
The antimony spots are readily dissolved by a drop of nitric
acid, and the liquid leaves on evaporation a white, residue,
which is not colored by the addition of a drop of silver nitrate
solution. Under the same circumstances, the arsenical spots
leave a white residue, which assumes a brick-red color when
moistened with a solution of silver nitrate, owing to the for-
mation of silver arsenate.
COMPOUNDS OF ANTIMONY AND CHLORINE.
Two chlorides of antimony are known :
Antimony trichloride.
Antimony pentachloride.
SbC13
SbC15
Antimony Trichloride, SbCl³.-This compound, formerly
COMPOUNDS OF OXYGEN AND ANTIMONY.
187
known as butter of antimony, is formed by the action of hy-
drochloric acid upon antimony sulphide. It is generally pre-
pared in the laboratory from the residue from the preparation
of hydrogen sulphide. This acid liquid is distilled in a retort
provided with a receiver, which is changed as soon as the anti-
mony chloride which distils over begins to crystallize in the
neck of the retort.
This chloride is solid, transparent, and colorless. It melts
at 73.2°, and boils at 230°. It dissolves in water charged
with hydrochloric acid, forming a colorless solution, but when
this liquid is diluted with water there is formed an abundant
white precipitate, long known as powder of Algaroth. It is
an oxychloride of which the composition does not appear con-
stant. There is one which contains SbOCl, and which can be
regarded as antimony trichloride, in which two atoms of chlo-
rine have been replaced by one atom of oxygen.
It is formed by a double decomposition, according to the
following reaction:
SbCl³ + H2O 2HCl + SbOCI
Antimony Pentachloride, SbC.-This is formed by the
action of an excess of chlorine upon antimony or upon the
trichloride. It is a yellow liquid, giving off white fumes in the
air. It is volatile, but cannot be distilled without undergoing
a partial decomposition into chlorine and antimony trichloride.
When exposed to the air, it absorbs moisture and is converted
into a crystalline mass, which is a hydrate of the pentachloride.
When treated with a large excess of water, it is decomposed
with production of heat, and formation of pyrantimonic and
hydrochloric acids.
COMPOUNDS OF OXYGEN AND ANTIMONY.
Two oxides of antimony are known, corresponding to those
of phosphorus and arsenic:
Antimonous oxide.
Antimonic oxide
Sb203
Sb205
Normal antimonic acid, H³SbO*, corresponding to phosphoric
and arsenic acids, is not known in the free state, but a derivative
of this acid exists and may be regarded as antimony antimonate.
Its composition is Sb2O*, and it is derived from antimonic acid
188
ELEMENTS OF MODERN CHEMISTRY.
by the substitution of an atom of antimony for three atoms of
hydrogen.
H3Sb04 antimonic acid.
SbSb0+ antimony antimonate.
There is a pyrantimonic and also a metantimonic acid,
analogous to the corresponding phosphorus acids :
H+Sb207 pyrantimonic acid.
HSb03 metantimonic acid.
ANTIMONOUS OXIDE.
SL203
This is obtained by oxidizing the metal in the air. The
operation may be conducted in two crucibles placed one above
the other, an opening being pierced in the upper one for the
access of air. They are heated to redness in a furnace, and on
cooling, the antimony is found to be partially converted into
brilliant needles that the ancients called silver flowers of anti-
mony. The crystals are right rhombic prisms, mixed with
regular octahedra, for antimonous oxide crystallizes in two
forms, presenting the same character of dimorphism as arsenious
oxide. The two compounds are hence said to be isodimorphous.
When solution of sodium hydrate, or better, sodium carbon-
ate, is poured into solution of antimony trichloride, a white
precipitate of antimonous hydrate is formed, and, in the latter
case, carbonic acid gas is disengaged.
SLC³ +
Sodium chloride.
3NaOH
H³SbO³ + 3NaCl
Sodium hydrate. Antimonous hydrate.
This hydrate readily parts with a molecule of water, being
converted into another hydrate, HSbO².
H³SbO³ H2O
HSbO2
ANTIMONY ANTIMONATE.
Sb204
This compound is formed when antimonous oxide is heated
for a long time in the air, oxygen being absorbed, or when
antimonic oxide is strongly calcined, oxygen being then disen-
gaged.
It is a white, infusible powder, undecomposable by heat and
insoluble in water.
ANTIMONIC OXIDE AND ACIDS.
189
ANTIMONIC OXIDE AND ACIDS.
When powdered antimony is heated with concentrated nitric
acid, a white powder is obtained, which is metantimonic acid.
It contains one atom of hydrogen capable of being replaced by
an equivalent quantity of metal, and thus corresponds to meta-
phosphoric acid.
HPO3
HSbO3
KSBO³
Metaphosphoric acid. Metantimonic acid. Potassium metantimonate.
When it is heated to dull redness, it loses water and is con-
verted into antimonic oxide.
2HSbO3 H2O = Sb2O5
If antimony pentachloride be poured into an excess of
water, a white precipitate of pyrantimonic acid is formed.
It is the analogue of pyrophosphoric acid, and, like the latter,
contains four atoms of hydrogen.
H&P²O
Pyrophosphoric acid.
H¹Sb2O
K+Sb2O
Pyrantimonic acid. Potassium pyrantimonate.
According to Fremy, potassium pyrantimonate may be
obtained by heating metantimonic acid or potassium metanti-
monate with potassium hydrate, in a silver crucible.
2KSbO³ + 2KOH
Potassium
metantimonate.
Potassium
hydrate.
K¹Sb²O² + H²O
Potassium
pyrantimonate.
The metantimonate may be extracted by water, in which it
is soluble, from the white mass, called by the ancients dia-
phoretic antimony, which is obtained by deflagrating in a red-
hot crucible a mixture of 2 parts of nitre (potassium nitrate)
and 1 part of powdered antimony. Cold water first dissolves
potassium nitrate from this mass, and then potassium metanti-
monate. The solution of the latter salt produces with hydro-
chloric acid a white precipitate of metantimonic acid.
SULPHIDES OF ANTIMONY.
Two sulphides of antimony are known:
Antimony trisulphide, or antimonous sulphide
Antimony pentasulphide, or antimonic sulphide
Sb2S3
Sb2S5
Antimonous Sulphide, Sb S3-This compound, ordinarily
called sulphide of antimony, occurs both in the crystalline
190
ELEMENTS OF MODERN CHEMISTRY.
form and amorphous. Crystallized, it exists in nature and is
the mineral commonly known as stibium. It is separated from
its gangue by fusion, and is thus obtained in gray masses com-
posed of brilliant needles having a metallic lustre.
Amorphous, it constitutes the orange-colored precipitate
formed by the action of hydrogen sulphide upon a solution of
antimony chloride. This precipitate is insoluble in ammonia,
but dissolves in ammonium sulphide and in the alkaline sul-
phides.
Antimony trisulphide is reduced by hydrogen at a high
temperature; hydrogen sulphide is formed, and metallic anti-
mony remains.
When heated in the air, antimony sulphide is oxidized with
formation of sulphurous oxide and antimonous oxide. The
incompletely roasted residue melts at a red heat, and on cool-
ing assumes the form of a brown vitreous mass called glass
of antimony. It is an impure oxysulphide which appears to
SbS
contain the compound Sb2S2O =
SbS
0.
Antimony Pentasulphide, Sb'S5.-When finely-pulverized
antimony trisulphide is digested with sulphur and a solution
of sodium hydrate, or a mixture of sulphur, sodium carbonate,
and lime, the antimony sulphide gradually dissolves in the
liquid, combining both with sulphur and with the sodium sul-
phide formed. The product of the reaction is a sulphantimo-
nate of sodium, which is deposited in fine crystals from the
concentrated liquid.
Sb2S5 + 3Na'S
Sodium sulphide.
2Na³SbS¹
Sodium sulphantimonate.
The crystals of this compound contain 9 molecules of water
of crystallization. It corresponds to the sulpharsenate already
mentioned, and to trisodium phosphate, Na³PO¹.
It is soluble in water, and on the addition of hydrochloric
acid to its solution, hydrogen sulphide is disengaged and anti-
mony pentasulphide is precipitated.
2Na³SbS* + 6HCl 6NaCl + Sb²S³ + 3H²S
General Considerations upon the Elements of the Nitro-
gen Group.-Nitrogen, phosphorus, arsenic, and antimony,
and bismuth might be added, form a group of elements allied
by the most striking analogics. This is made manifest by the
BORON.
191
atomic composition of their compounds, as will be seen in the
following synopsis:
HYDROGEN COMPOUNDS.
NH³
PH³
AsH³
3
SbH³
Ammonia. Hydrogen phosphide. Hydrogen arsenide. Hydrogen antimonide.
CHLORINE COMPOUNDS.
NCI 3
Nitrogen
trichloride.
PC13
Phosphorus
trichloride.
AsCl3
Arsenic
trichloride.
PC15
Phosphorus pentachloride.
OXYGEN COMPOUNDS.
SbCl³
Antimony
trichloride.
SbC15
Antimony pentachloride.
N203
P203
As²03
Sb2O3
Nitrogen trioxide.
Phosphorous oxide.
Arsenious oxide.
Antimonous oxide.
N205
P2O5
As205
Sb2O5
Nitrogen pentoxide. Phosphoric oxide.
Arsenic oxide.
Antimonic oxide.
H³PO3
Phosphorous acid.
3
H³AsO³
Arsenious acid.
HNO2
Nitrous acid.
H³PO
Phosphoric acid.
H³ AsO¹
Arsenic acid.
H¹P207
H+As2O¹
H3SbO³
Antimonous acid.
HSbO2
Antimonyl hydrate.
H+Sb2O7
HNO3
Pyrophosphoric acid. Pyro-arsenic acid. Pyro-antimonic acid.
HPO³
HASO³
3
Nitric acid. Metaphosphoric acid. Metarsenic acid.
HSbO³
Metantimonic acid.
If the analogy between nitrogen and phosphorus were com-
plete, there should be an orthonitric acid, H³NO¹
HNO3 +
H2O, corresponding to ordinary or orthophosphoric acid. This
acid is not known as a definite hydrate, but compounds exist
which are derived from it. Thus, bismuth subnitrate, BiNO*,
can be regarded as a salt of orthonitric acid, in which three
atoms of hydrogen are replaced by one atom of triatomic
bismuth.
BORON.
Bo
11
Boron is the radical of boric acid. It exists in the amor-
phous state and crystallized. It was discovered by Gay-Lussac
and Thenard in 1808.
192
ELEMENTS OF MODERN CHEMISTRY.
Preparation. 1. Amorphous Boron.-Boric oxide is re-
duced by sodium at a red heat, and the cooled mass is treated
with dilute hydrochloric acid. The sodium borate which is
formed is thus dissolved, and a residue consisting of amorphous
boron is obtained as a dark powder.
2B0203
Boric oxide.
+ 3Na²
Sodium.
2Na³ Bo0³ + Bo²
Sodium borate.
2. Crystallized Boron.-Boric oxide is fused with alumin-
ium; a part of this metal reduces the boric oxide and becomes
oxidized, while another part dissolves the boron set free, and
again deposits it in the crystalline form on cooling (H. Sainte-
Claire Deville).
Al² + Bo²0³ Al2O3 + Bo²
Its
Amorphous
Properties. Amorphous boron is a dark-brown powder, or
brown bordering upon green. It is infusible. Heated to 300°
in the air, it burns, being converted into boric oxide.
combustion in pure oxygen is very brilliant.
boron possesses a singular affinity for nitrogen. At a red heat
it absorbs this gas, forming a nitride of boron, BoN. When
heated to dull redness in an atmosphere of nitrogen dioxide, it
burns into a mixture of boric oxide and boron nitride (Wöhler
and Deville).
Crystallized boron occurs as square octahedra (Sella). In
this form it is almost as hard as the diamond, and will scratch
rubies. The color of the crystals varies from yellow to deep
garnet-red; sometimes they appear black. Their density is
2.63.
Crystallized boron energetically resists oxidation, both when
it is heated in oxygen and when it is subjected to the action of
fused potassium nitrate. At a bright-red heat it reacts upon
potassium acid sulphate, sodium hydrate, and sodium carbonate.
It burns in chlorine at a red heat.
BORON CHLORIDE.
BOC13
Preparation. This body, which was discovered by Berze-
lius, is prepared by Wöhler and Deville by heating perfectly
dry, amorphous boron in a current of chlorine gas, and passing
the vapor of boron chloride formed into a receiver surrounded
by a mixture of ice and salt.
BORON FLUORIDE.-BORIC ACID.
193
Properties. In a state of purity, boron chloride is a color-
less, mobile, and highly-refractive liquid, boiling at 17°. It
fumes in the air, and is readily decomposed by water into boric
and hydrochloric acids.
BoCl³ + 3H20= 3HCl + Bo(OH)3
BORON FLUORIDE.
BoF13
Density compared to air
•
2.31
34.
Density compared to hydrogen
Preparation.-Boron fluoride was discovered by Gay-Lussac
and Thenard in 1810. It is prepared by heating in a glass
retort an intimate mixture of one part of boric oxide and two
parts of powdered calcium fluoride with twelve parts of sul-
phuric acid. The gas disengaged is collected over mercury.
3CaFl² + Bo²0³ + 3H³SO¹ 3CaSO¹ + 3H²0 + 2B0Fl³
Calcium sulphate.
Calcium
fluoride.
Boric oxide.
Properties.-Boron fluoride is a colorless gas, having a suf-
focating odor. It produces abundant fumes in the air, and is
very soluble in water, which dissolves about 800 times its
volume of this gas. Its affinity for water is so great that it
carbonizes paper and analogous organic substances, from which
it removes the elements of water.
The solution of boron fluoride in water is accompanied by a
chemical reaction; when the aqueous solution of this gas, satu-
rated at the ordinary temperature, is cooled to 0°, crystals of
boric acid are deposited, and a very acid liquid is obtained,
known as hydrofluoboric acid; its composition is expressed by
the formula:
BOFIH
BoFl³. HFl
BORIC ACID.
H³BOO³
Preparation.-Boric acid was discovered by Homberg in
1702. It is found in the free state in the craters of certain
volcanoes, and exists in solution in the lagoni of Monte-
Rotondo, in Tuscany. These are muddy little lakes, through
which arise the gaseous emanations from the fissures of a vol-
canic soil. The gases (suffioni) contain sensible traces of boric
I
17
194
ELEMENTS OF MODERN CHEMISTRY.
acid, which is dissolved by the water of the lagoni. On evap-
oration, this water furnishes the crude boric acid.
Large quantities of borax (sodium borate) are obtained from
Borax Lake and from Lake Clear, about two hundred and fifty
miles north of San Francisco, California. The crude borax is
extracted from a muddy deposit, which is obtained from the
bottom of the lakes by dredging.
In the laboratory, boric acid is prepared by decomposing a
boiling saturated solution of borax or sodium borate with dilute
sulphuric acid. The latter is added in small portions until
the liquid strongly reddens litmus-paper; the solution is then
allowed to cool, and the boric acid separates in the crystalline
form.
Properties. Pure boric acid crystallizes in pearly scales,
somewhat greasy to the touch. It dissolves in 25 parts of
water at 18°, and is much more soluble in boiling water. The
solution is feebly acid, and changes blue litmus solution to a
wine color. Boric acid dissolves in alcohol, and the solution.
burns with a green flame.
When boric acid is heated in a platinum crucible to a tem-
perature near redness, it loses all of its water, melts, and solidi-
fies to a transparent glass on cooling. This is boric oxide.
2H³B00³ — Bo²0³ + 3H²0
At a red heat this body dissolves a great number of solid sub-
stances, particularly the metallic oxides; it then yields variously
colored glasses on cooling.
Boric oxide is not decomposed by charcoal at a red heat, but
if a current of chlorine be passed over an intimate mixture of
boric oxide and charcoal, heated to bright redness in a porce-
lain tube, boron chloride and carbon monoxide are formed
(Dumas).
Bo²0³ + 3C + 3C1² = 2B0C¹³ + 3CO
SILICON.
Si = 28
Like boron, silicon exists amorphous and in the crystalline
form. It was discovered by Berzelius in 1825.
Preparation. 1. Amorphous Silicon.-Well-dried sodium
SILICON.
195
fluosilicate is heated with half its weight of metallic sodium:
sodium fluoride is formed and silicon is set free.
Na²Fl².SiFl¹ + 2Na²
Sodium fluosilicate.
6NaFl+Si
Sodium fluoride.
On cooling, the mass is exhausted, first with cold, and after-
wards with hot, water; a brown powder of amorphous silicon
remains.
2. Crystallized Silicon.-Deville and Caron obtained crys-
tallized silicon by projecting a mixture of 3 parts of potassium
and silicon double fluoride, 4 parts of zinc, and 1 part of
sodium into a red-hot crucible. Fluoride of sodium is formed,
and the silicon set free dissolves in the zinc and separates in
the crystalline form on cooling; it is isolated from the zinc
by dissolving the button in hydrochloric acid; the silicon
remains in the form of brilliant laminæ or needles. These
crystals are of a dark steel-gray color, and possess a metallic
lustre; they are composed of chaplets of regular octahedra.
Properties.-Amorphous silicon is a brown powder, more
dense than water, in which it is insoluble, and producing dark
stains on the fingers. When heated in the air. it takes fire and
burns with a bright light into silicic oxide, SiO².
Crystallized silicon has a density of 2.49. It may be heated
to redness in oxygen without taking fire, but when it is calcined
with potassium carbonate the latter is decomposed with a vivid
emission of light, potassium silicate being formed and carbon
being set free. Crystallized silicon resists the oxidizing action
of both potassium nitrate and potassium chlorate, but it dis-
solves slowly in a boiling solution of potassium hydrate, hydro-
gen being disengaged and potassium silicate being formed. It
burns when heated to redness in an atmosphere of chlorine,
silicon chloride being formed.
HYDROGEN SILICIDE.
Probable formula SiH4
Preparation. This compound was discovered by Wöhler
and Buff in 1857. Magnesium silicide* is introduced into a
two-necked bottle, which is then entirely filled with water that
* Wöhler prepares this silicide by fusing in a crucible a mixture of 40
parts of magnesium chloride, 35 parts of silicon and sodium double fluor-
ide, and 10 parts of sodium chloride, these salts being previously mixed
with 10 parts of sodium in minute fragments.
196
ELEMENTS OF MODERN CHEMISTRY.
has been recently boiled. One of the necks of the bottle is
fitted with a funnel-tube which passes to the bottom of the
bottle, while to the other is adapted a delivery-tube leading to
the pneumatic trough; this tube also should be completely filled
with water so that there is not a single bubble of air in the
whole apparatus. Concentrated hydrochloric acid is then
introduced by the funnel-tube, and immediately reacts with
the magnesium silicide, forming magnesium chloride, which
dissolves, and hydrogen silicide, which is disengaged and must
be collected in jars filled with recently boiled water.
Properties. The gas thus obtained is not pure hydrogen
silicide; it contains an excess of hydrogen. It is colorless and
insoluble in water from which the air has been expelled.
Water containing air in solution oxidizes it.
If bubbles of the gas be allowed to escape through the water
of the trough, each bubble takes fire on coming to the surface,
burning with a bright light and a little explosion, and producing
a white smoke of silicic oxide. This smoke forms rings like
those produced by hydrogen phosphide under the same circum-
stances, but often colored brown by a portion of silicon set free.
The incomplete combustion of hydrogen silicide is accompa-
nied by a brown deposit of amorphous silicon. At a red heat,
hydrogen silicide is decomposed into hydrogen and silicon.
SILICON CHLORIDE.
SiCl4
This compound is formed when silicon is heated to dull
redness in a current of chlorine, or when a current of the
latter gas
is passed over an incandescent mixture of charcoal
and silica.
SiO² + C² 1 C14
Silicic oxide.
SiCl + 2CO
Carbon monoxide.
Preparation.-Precipitated silica, lamp-black, and oil are
intimately mixed into a stiff paste. This paste is made into
little balls, which are put into a crucible, the cover of which is
then luted on, and the whole is heated to redness in a furnace.
When cool, the balls are introduced into a porcelain tube or a
clay retort (Fig. 74), which is then heated to bright redness,
while a current of carefully-dried chlorine is passed through.
The silicon chloride and the carbon monoxide formed are
SILICON FLUORIDE.
197
passed through two U tubes surrounded by a mixture of ice
and salt. The silicon chloride is thus condensed.
Properties. Silicon chloride is a volatile, colorless liquid,
of an irritating odor. It fumes in the air. Its density is 1.52,
and it boils at 59°.
It is instantly decomposed by water, silicic and hydrochloric
acids being formed. A part of the silicic acid is precipitated.

FIG. 74.
in the form of a jelly, while another part remains in solution.
The latter is perhaps a hydrate corresponding to the chloride.
SiC¹¹ + 4H²0 = 4HCl + Si(OH)*
There exists a tetrabromide of silicon, SiBr¹, and a tetra-
iodide, SiI+, both corresponding to the chloride which has just
been described.
Friedel has recently discovered an iodide, Si I, remarkable
as belonging to an entirely new series.
SILICON FLUORIDE.
SiFl
Density compared to air
•
Density compared to hydrogen
3.6
52.
Preparation. An intimate mixture of silicious sand and
17*
198
ELEMENTS OF MODERN CHEMISTRY.
finely-powdered calcium fluoride, or fluor spar, is introduced.
into a glass flask (Fig. 75), and a sufficient quantity of sul-
phuric acid is added to reduce the whole to a creamy consistence.
A gentle heat is applied, and the gas disengaged may be col-
lected over mercury.
2CaFl² + 2H2SO4 + SiO2
Calcium fluoride.
2CaSO¹ + SiFl¹ + 2H2O
Silicic oxide. Calcium sulphate.

FIG. 75.
Properties.-Silicon fluoride is a colorless, suffocating gas,
producing white fumes when allowed to escape into the air. It
may be liquefied by a low temperature and a strong pressure.
On contact with water it is decomposed, silicic hydrate separat-
ing in gelatinous flakes, and hydrofluosilicic acid being formed.
3SiFl¹ + 3H2O 2(H2F12.SiF) + H2SiO³
Hydrofluosilicic acid.
Hydrofluosilicic Acid.-A saturated, aqueous solution of
this acid is a highly acid liquid, fuming in the air, and evapo-
rating slowly at 40° from a platinum-dish without leaving any
residue.
It is prepared by passing gaseous silicon fluoride into water
under which is a layer of mercury. The delivery-tube must
dip beneath the surface of the mercury, so that the silicon flu-
oride can only come in contact with the water after passing
through the metal; otherwise the delivery-tube would become.
obstructed by the deposit of gelatinous silica.
Hydrofluosilicic acid is employed as a reagent in the labora-
tory. It precipitates the salts of potassium and sodium, form-
ing insoluble fluosilicates, R2F12.SIFI.
SILICIC OXIDE AND ACIDS.
199
SILICIC OXIDE AND ACIDS.
(SILICA.)
Native State.-Silicic oxide is widely diffused in nature.
It occurs crystallized, as the different varieties of quartz; amor-
phous, as agate, chalcedony, cornelian, flint, etc.; granulated, it
is found in sandstones and the sand produced by their disaggre-
gation; in this case it is often mixed with variable quantities
of alumina and oxide of iron.
Rock-crystal is pure silicic oxide. It occurs as six-sided
prisms, terminated by pyramids of six faces (Fig. 76).
As hydrate, silica exists in various minerals, such
as opal and hydrophane. It is also found in the
form of pulverulent deposits and in solution in
many running waters, in large proportion in the
hot waters of the geysers in Iceland.

FIG. 76.
Properties. Quartz is infusible at the highest
furnace heats, but undergoes a viscous fusion when
introduced into the flame of the oxyhydrogen blow-
pipe. Neither carbon nor potassium is capable of
reducing it, even at the highest temperatures. It
is not attacked by acids, with the exception of hydrofluoric
acid. Boiling alkaline solutions scarcely affect it, but the amor-
phous varieties of silica, such as flint, as well as opal and the
other hydrates, dissolve more readily in boiling solutions of the
alkaline hydrates.
All of the varieties of silica, when heated to redness with
the alkalies or alkaline carbonates, combine with the bases,
forming silicates which enter into fusion at a high temperature
and solidify to a vitreous mass on cooling. Potassium silicate,
or soluble glass, is a transparent mass, soluble in water. When
hydrochloric acid is added to this solution, potassium chloride
is formed and silicic acid is precipitated as a gelatinous mass,
which is not insoluble in water. An aqueous solution of silicic
acid may be obtained.
If hydrochloric acid be added to a dilute solution of potas-
sium silicate, the liquid remains transparent although it contains
silicic acid. It may be poured into a dialyser, composed of a
piece of parchment-paper stretched over a wooden or glass ring,
and floated on the surface of pure water contained in another
vessel. The potassium chloride gradually passes through the
200
ELEMENTS OF MODERN CHEMISTRY.
membrane, as would any crystallizable body, and the silicic
acid remains alone dissolved in the water in the dialyser, as
all other amorphous bodies which are soluble in water would
do. Graham gave the name dialysis to this separation of crys-
tallizable bodies, which he named crystalloids, from uncrystal-
lizable bodies, which he named colloids, by means of certain
membranes. The former bodies pass through the membranes,
which are, however, impermeable to the colloids.
The silicic acid which remains in solution probably consti-
tutes normal silicic acid, H⭑SiO* SiO² + 2H2O.
This hydrate is not known in the pure state. Ebelmen has
described a hydrate, H2SiO³, which may be considered as the
first hydrate of silicic oxide.
H¹SiO¹
H+SiO¹
H2O H2SiO3
2H2O
SiO2
There are other silicic hydrates having more complex com-
positions.
Uses.-Silica is largely employed in all of its various forms.
Crystallized quartz, or rock crystal, is used for the manufacture
of ornaments, spectacle-glasses, and lenses. Chalcedony, onyx,
and opal are sought for by the lapidary and engraver. Agate,
which is very hard, is used for the manufacture of mortars, etc.
Sandstones serve for building purposes and for grindstones;
sand, for mortars and the manufacture of glass and pottery.
CARBON.
C = 12
Natural State and Varieties.-The carbon of chemists is
pure charcoal. This substance is known to all; black, friable,
light, absolutely fixed, inalterable by the air at ordinary tem-
peratures, but combustible when heated in the air, it results
from the calcination of organic matters, and particularly wood,
in closed vessels. But carbon by no means always reveals
these same properties. It occurs in nature under forms so
different that it is impossible to apply a general description to
all of its known varieties. What could be more different, as
far as physical properties are concerned, from the soot deposited
by a smoky flame, or the light, porous, and opaque charcoal,
than the hard, dense, and transparent substance found in nature
CARBON.
201
in the form of diamond?
Nevertheless, these bodies are com-
posed of one and the same substance, carbon; alike, they all
burn in oxygen at a high temperature, producing carbonic acid
gas.
Among the various forms which carbon assumes, and which
constitute one of the most curious examples of dimorphism, the
following may be described:
Diamond. This is the hardest of all bodies; it scratches all
others, and can only be trimmed by grinding with its own dust.
It is found crystallized in the form of the regular octahe-
dron and the modifications thereof, among which must be men-

A
B
C
D
FIG. 77.
tioned the polyhedra of twenty-four and forty-eight faces. The
faces are generally convexly curved (Fig. 77).
The density of the diamond is between 3.50 and 3.55. It is
a bad conductor of heat and electricity; it strongly refracts and
disperses light. From this latter fact Newton first divined its
combustible nature, which was proved, in 1694, by the Floren-
tine academicians of del Cimento, who burned a diamond in the
focus of a concave mirror. Lavoisier and Davy repeated this
celebrated experiment. Exposed to the high temperature of
the voltaic are between two carbon poles in a vacuum, the dia-
mond swells up, blackens, and is converted into a substance
analogous to coke (Jacquelain).
Graphite, or Plumbago.-This is a crystalline variety of
carbon, which is found in primitive rocks in brilliant steel-gray
foliated masses. It sometimes occurs in hexagonal laminæ.
It can be scratched with the finger-nail, and leaves a black
trace when drawn over paper. Its density is 2.2, and it con-
ducts heat and electricity. It burns only at very high tem-
peratures; ordinarily, it contains from one to two per cent. of
foreign matters.
I*
202
ELEMENTS OF MODERN CHEMISTRY.
It has been obtained artificially. Melted iron possesses the
property of dissolving carbon at a very high temperature, and
again depositing it on cooling in the form of hexagonal scales
of graphite.
Plumbago is used for the manufacture of lead-pencils and
crucibles, and is called black lead.
There are other natural varieties of carbon, but they are
far from presenting the same degree of purity as diamond or
graphite. They are:
Anthracite, a hard and compact variety of carbon containing
from 8 to 10 per cent. of earthy matters.
Bituminous coal, a brilliant, black variety, strongly impreg-
nated with bituminous and earthy matters.
It has been pro-
duced by the slow decomposition of vegetable matters buried
in the earth in the early geological ages. This origin is indi-
cated by the impressions of leaves, stems, and fruits, which are
evident in certain specimens of this coal. It contains only
from 75 to 88 per cent. of carbon. When it is calcined in
closed vessels, it disengages combustible gases and products
which may be condensed in the liquid form and then separate
into two layers. One is aqueous and ammoniacal, while the
other is composed of tar. The residue of the distillation of
bituminous coal is coke. The interior walls of the cast-iron
vessels in which coal is distilled become covered with a com-
pact layer of a gray, dense, hard and sonorous carbon, which
is a good conductor of heat and electricity. This is the carbon
of gas-retorts, and is produced by the igneous decomposition.
of hydrocarbons rich in carbon, which are disengaged during
the calcination of the coal.
Fat coals are those which burn with a long flame, softening
in burning; dry coals burn with a short flame which produces
less heat than the preceding.
Lignite is a combustible mineral containing less carbon, and
more impure than bituminous coal; it is found in the lower
tertiary formations. Natural jet, which is employed for the
manufacture of ornaments, is a variety of lignite.
Among the artificial carbons, independently of coke, may
be mentioned wood charcoal, lamp-black, and animal char-
coal.
Wood Charcoal.-When wood is calcined in closed vessels
it leaves a residue which is ordinary charcoal. It is prepared
on the large scale by two processes, carbonization in stacks,
CARBON.
203
which is carried on in the forests, and distillation in closed
vessels. Charcoal is amorphous, brittle, and sonorous, a bad
conductor of heat and electricity. Its density does not exceed
1.57. The lighter varieties are the more combustible. Its
combustion leaves a residue of one or two per cent. of cinders,
formed principally of mineral salts, among which the most
abundant are the carbonates of calcium and potassium.

E
FEE
C
FIG. 78.
Lamp-black is produced by the incomplete combustion of
organic substances rich in carbon.
burned, a dense smoke is produced
When rosin or tallow is
which is composed of par-
204
ELEMENTS OF MODERN CHEMISTRY.
ticles of carbon that have escaped combustion. In the arts,
lamp-black is procured by burning rosin in cast-iron pots, C
(Fig. 78), heated by a fire, F. The vapors given off are ig-
nited, and the smoke is conducted into a chamber, A, the walls
of which are hung with canvas. On this the lamp-black is de-
posited, and is detached by lowering the cone B, which acts as
a scraper. Lamp-black is not pure carbon. It contains tarry
and oily matters, from which it may be freed by calcination in
a covered crucible. It is used for the manufacture of printing-
inks.
Animal charcoal is produced by calcining animal matters,
such as blood, the débris of skin, horn, bone, etc., in closed
vessels. Bone-black or ivory-black contains the calcareous
salts, calcium phosphate and carbonate, which form the base.
of the osseous tissue. The carbon is consequently disseminated
through a porous mass. These salts may be extracted by
treating the bone-black with dilute hydrochloric acid, by which
they are dissolved. The residue, washed with water and dried,
is known as washed or purified animal charcoal.
Absorbent Properties of Charcoal.-The amorphous and
porous varieties of carbon, of which several forms have been
described, possess the property of absorbing and retaining in
their pores, gases, liquid and solid bodies. It is to this absorp-
tive faculty that are due the decolorizing and disinfecting
properties of charcoal, which are made use of to a large extent
in the arts.
If a piece of incandescent charcoal be plunged into mercury
that it may cool out of contact with the air, and then be intro-
duced into a small jar filled with ammonia or hydrochloric acid
over the mercury-trough, the gas is at once absorbed and the
mercury rises in the jar.
The following table, by Th. de Saussure, indicates the quan-
tities of several gases which are absorbed by one volume of
charcoal :
1 volume of charcoal absorbs 90 volumes of ammonia.
66
"C
66
((
66
(
(6
if
85
65
55
40
35
9.42
(6
9.25
7.50
1.75
(6
hydrochloric acid.
sulphurous oxide.
hydrogen sulphide.
nitrogen monoxide.
carbon dioxide.
carbon monoxide.
oxygen.
"nitrogen.
hydrogen.
CARBON.
205
Charcoal increases in weight when exposed to the air, for
it absorbs and condenses the atmospheric moisture. When
plunged into water charged with a small quantity of hydrogen
sulphide, it absorbs that gas and removes the odor of the water.
The disinfecting properties of charcoal are thus easily explained.
It is well known that charcoal will remove the unpleasant odor
of corrupted waters, of meats slightly spoiled, and in general
of organic matters in a state of putrefaction. A layer of char-
coal between two layers of sand is an excellent filter for the
clarification of drinking waters.
The decolorizing properties of charcoal are another mani-
festation of this general faculty of absorption, which is pos-
sessed in the highest degree by animal charcoal. If litmus
solution or red wine be agitated with a sufficient quantity of
animal charcoal and subsequently filtered, the liquids pass
through colorless.

FIG. 79.
This property of animal charcoal is largely applied in the
arts, particularly for decolorizing sugars and syrups.
Chemical Properties.- Carbon is distinguished by its
powerful affinity for oxygen, an affinity which is not, however,
18
206
ELEMENTS OF MODERN CHEMISTRY.
exercised except at high temperatures. It only combines with
oxygen at a red heat, and remains incandescent as long as com-
bination goes on, the heat produced by the combination being
sufficient to maintain the incandescence. In pure oxygen it
burns with a brilliant light. The product of the combustion
is carbonic acid gas.
By the aid of heat, carbon decomposes a great number of
oxygenized compounds, removing and combining with the
whole or a part of their oxygen. This decomposition takes
place at comparatively low temperatures when the oxygenized
body does not strongly retain its oxygen; in this case, carbon
dioxide is formed, and the reduction of cupric oxide by char-
coal furnishes an example. In the contrary case, the reduction,
that is, the decomposition of the oxidized body, requires a very
high temperature; carbon monoxide is then formed. The re-
duction of zinc oxide by charcoal is an example.
If an incandescent charcoal be rapidly plunged under a bell-
jar filled with water on the pneumatic trough, bubbles of gas
arise and collect in the jar (Fig. 79). They are formed of a
mixture of hydrogen, carbon monoxide, and a small quantity
of carbon dioxide. These gases are produced by the decom-
position of the water by the charcoal, which was red-hot at the
moment of contact with the liquid.
C + H2O = H² + CO carbon monoxide.
Carbon combines directly with sulphur at a high tempera-
ture, forming carbon disulphide.
COMPOUNDS OF CARBON AND OXYGEN.
Two compounds of carbon and oxygen are known :
Carbon monoxide
Carbon dioxide, or carbonic acid gas
CO
CO2
The latter body, which has long been known as carbonic
acid, is the oxide corresponding to the true carbonic acid,
which would be
CO + H2O = HCO
CO² + =
This normal carbonic acid is as yet unknown: it is doubtless
too unstable to exist in the free state. However, its existence
CARBON MONOXIDE.
207
may be admitted, for a corresponding compound is known in
sulphocarbonic acid H²CS".
CARBON MONOXIDE.
Density compared to air.
Density compared to hydrogen
Molecular weight CO.
0.967
14.
28.
Preparation.-1. An intimate mixture of zinc oxide and
charcoal may be calcined in a clay retort.
ZnO + C
CO + Zn
2. A convenient method of preparing carbon monoxide con-
sists in heating oxalic acid with an excess of sulphuric acid in
a glass flask. The oxalic acid loses the elements of water,
which it yields to the sulphuric acid, and breaks up into carbon
dioxide and carbon monoxide.
C2H2O*
со + CO² + H2O
Oxalic acid. Carbon monoxide. Carbon dioxide.

B
FIG. 80.
The mixture of the two gases is passed through a wash-bottle,
B (Fig. 80), containing a solution of potassium hydrate, by
208
ELEMENTS OF MODERN CHEMISTRY.
which the carbon dioxide is absorbed, potassium carbonate being
formed. Carbon monoxide alone passes through, and may be
collected over water.
Properties.-Carbon monoxide is a colorless, odorless gas.
It is neutral, and does not trouble lime-water, which distin-
guishes it from carbon dioxide. It extinguishes burning bodies,
but is combustible itself, burning in the air with a blue flame,
and forming carbon dioxide. It is not only unfit for respira-
tion, but is very poisonous.
Composition.-If two volumes of carbon monoxide be
mixed with one volume of oxygen in an eudiometer, and a
spark be passed, complete combustion takes place, and the
three volumes of the primitive mixture are reduced to two
volumes of carbon dioxide. This can be verified by passing
into the eudiometer a solution of potassium hydrate, which will
completely absorb the new gas.
It hence follows that two volumes of carbon monoxide con-
tain the same quantity of carbon as two volumes of carbon
dioxide. Knowing from other circumstances that two volumes
of carbon dioxide contain two volumes of oxygen, it follows
that two volumes of carbon monoxide contain one volume of
oxygen. Its composition is then expressed by the formula
CO 2 volumes.
Carbon monoxide undergoes dissociation at a very high tem-
perature. By operating under special conditions, H. Sainte-
Claire Deville has succeeded in resolving it into carbon and
oxygen.
It is almost insoluble in water, but is absorbed by a solution
of cuprous chloride in hydrochloric acid (Doyère and F. Le
Blanc). Advantage is taken of this property in volumetric
analysis to separate carbon monoxide from certain other gases.
When heated for a long time to 100°, in sealed tubes with
potassium hydrate, it combines with the alkali, forming potas-
sium formate (Berthelot).
CO + KOH
KCHO2
Potassium hydrate. Potassium formate.
It is a beautiful synthesis of formic acid, so named because it
exists in ants.
Action of Chlorine upon Carbon Monoxide. Under the
influence of sunlight, carbon monoxide combines directly with
chlorine, forming a gas which is known as chloro-carbonic oxide,
CARBON DIOXIDE.
209
or carbonyl chloride.
It was formerly called phosgene gas.
One volume of carbon monoxide combines with one volume of
chlorine to form one volume of carbonyl chloride, so that the
density of the latter is equal to the sum of the densities of
carbon monoxide and chlorine.
Compared to Hydrogen. Compared to Air.
Density of carbon monoxide.
Density of chlorine.
•
14.
35.5
Density of carbonyl chloride 49.5
•
0.967
2.44
3.407
At ordinary temperatures, carbonyl chloride is a colorless
gas, having a suffocating odor that provokes tears. At a low
temperature, it condenses to a colorless liquid, boiling at 8.2°
(Emmerling and Lengyel). It is instantly decomposed by water,
with the formation of carbon dioxide and hydrochloric acid.
COCI² + H2O = 2HC CO²
Its mode of formation, its composition, and its properties
indicate its relations to carbon dioxide.
2 volumes CO absorb 2 volumes of chlorine to form 2 volumes CO.C12
2 volumes CO absorb 1 volume of oxygen to form 2 volumes CO.0
It is seen that carbon monoxide plays to a certain extent the
part of a radical; it combines directly with oxygen or with
chlorine to form either oxide or chloride of carbonyl. It
is seen also that carbonyl chloride represents carbon dioxide in
which one atom of oxygen is replaced by two atoms of chlorine.
CARBON DIOXIDE.
Density compared to air
Density compared to hydrogen
Molecular weight CO2.
1.529
22.
44.
This gas was discovered by Black in 1648, and its composi-
tion was recognized by Lavoisier in 1776. It is one of the
constituents of the atmosphere, and is the product of a great
number of reactions which take place on the earth's surface,
such as the combustion of carbon and organic matters, respira-
tion, and the phenomena of putrefaction and fermentation. It
issues from the soil of volcanic countries.
18*
212
ELEMENTS OF MODERN CHEMISTRY.
a centesimal relation which is expressed more simply by the
numbers
Carbon.
Oxygen
12
32
44
12 being the weight of one atom of carbon, and 32 the weight
of two atoms of oxygen.
Physical Properties.-Carbon dioxide is colorless; it has a
feeble, somewhat pungent odor. A litre of this gas at 0°, and
under the pressure of 760 millimetres, weighs 1.966 grammes.

碟
​7
WASANY
B
FIG. 83.
It is not permanent. Faraday succeeded in liquefying it at
a temperature of 0°, under a pressure of 36 atmospheres. The
apparatus which is now used for its liquefaction is represented.
in Fig. 83. It is composed of two reservoirs, A and B, com-
CARBON DIOXIDE.
213
municating by the metallic tube i, furnished with a stop-cock
at each end. The cylinders are made of heavy cast-iron, and
are further strengthened by forged iron bands forced over
their circumference. Each cylinder is movable on a horizon-
tal axis, h. B is the generator; into it are introduced 1800
grammes of sodium dicarbonate, and a cylindrical copper tube,
D, containing 1000 grammes of ordinary sulphuric acid. The
cylinder is then closed by a strong screw plug, and a few oscil-
lating movements are given to it in order that the sulphuric
acid may gradually run out upon the sodium dicarbonate.
Carbon dioxide is disengaged and is liquefied by its own press-
ure as it accumulates in the apparatus. By the effect of the
chemical action the temperature is raised to 30 or 40°, and,
communication being established between the two cylinders,
the carbon dioxide distils rapidly into the receiver, the tem-
perature of which is about 15°.
A
The operation is repeated several times, that one or two kilo-
grammes of the liquid may accumulate in the receiver.
tube passes to the bottom of this vessel, and on opening the
stop-cock which closes the superior extremity of this tube, a
jet of the liquid is thrown out with
force; it is received tangently in a
metallic box, A, A' (Fig. 84), having
very thin sides. In this a portion
of the oxide solidifies by reason of
the great depression of temperature
produced by the change of another
portion into the gaseous state.
A
glittering-white, flaky mass collects
in the receiver, having the appear-
ance of snow. This is solid carbon
dioxide. It is a bad conductor of
heat and electricity, and can be ex-
posed to the air for a few minutes
before it disappears. In reassuming the gaseous form, it pro-
duces an intense cold. If it be mixed with ether, the mixture,
which is less porous and a better conductor of heat, can produce
a lowering of temperature as great as —90°. By pouring it
upon mercury, large masses of that metal may be frozen.


FIG. 84.
Drion and Loir have recently succeeded in collecting and
maintaining carbon dioxide in the liquid state. It is colorless
and mobile; has a density of 0.72 at +27°, and 0.98 at —8°.
214
ELEMENTS OF MODERN CHEMISTRY.
This considerable difference between the densities is due to the
enormous dilatation which the liquid undergoes between these
limits of temperature. Indeed, ten volumes of liquid carbon
dioxide at 0° occupy fourteen volumes at 30°. The coefficient
of dilatation of the liquid is then superior to that of the gas.
Carbon dioxide is incombustible, and extinguishes burning
bodies.
If carbon dioxide be poured from one vessel into another
containing a lighted candle, it falls upon the flame like water,
extinguishing it at once (Fig. 85).

\\\//
FIG. 85.
Lime-water poured into a jar
of carbon dioxide becomes clouded,
owing to the formation of insolu-
ble calcium carbonate.
These experiments permit the
easy recognition of carbon dioxide
from carbon monoxide.
Carbon dioxide dissolves in its
own volume of water at 15° under
the normal pressure. If the press-
ure be increased, the solubility of
the gas is increased in the same
proportion. Thus, under a press-
ure of ten atmospheres one litre
of water will dissolve ten litres of
carbon dioxide; but it must be remembered that under a press-
ure of ten atmospheres these ten litres are reduced to one litre.
Thus, one litre of water, which dissolves one litre of carbon
dioxide at the ordinary pressure, dissolves also one litre under
a pressure of ten atmospheres, and it may be said that water
always dissolves its own volume of carbon dioxide, whatever
may be the pressure. Water saturated with carbon dioxide
under strong pressure, disengages a portion of the gas as soon
as the pressure is removed. Such water is universally known
and consumed in large quantities under the name of gaseous
water or soda water.
The solution of carbon dioxide exercises a much more ener-
getic solvent action upon certain substances than pure water.
It dissolves calcium carbonate, forming a soluble dicarbonate;
it is even capable of dissolving calcium phosphate, transform-
ing it into acid phosphate, which is soluble.
Carbon dioxide is more soluble in alcohol than in water.
CARBON DISULPHIDE.
215
It is undecomposable by heat alone, but may be decomposed
or reduced at high temperatures by contact with bodies avid
of oxygen. Such substances are hydrogen and carbon. With
the latter body the reduction takes place at a red heat, giving
rise to the formation of carbon monoxide, the volume of which
is double that of the carbon dioxide employed.
CO2 + C
Carbon dioxide (2 vols.).
2CO
Carbon monoxide (4 vols.).
CARBON DISULPHIDE.
CS2
This body is prepared by passing sulphur vapor over incan-
descent charcoal. In the arts, the operation is conducted in
cylindrical, cast-iron vessels, filled with charcoal and heated to
redness, into which sulphur is introduced. The carbon disul-
phide distils, and is condensed in a suitable cooling apparatus.
Carbon disulphide is a colorless, very mobile, and highly-re-
fracting liquid. Its odor is strong and unpleasant. Its density
at 15° is 1.271, and it boils at 46°. It is very inflammable, and
burns with a blue flame, producing sulphurous oxide and carbon
dioxide.
CS² + 06 2SO² + CO²
Its vapor, mixed with oxygen, explodes on the application
of flame.
Carbon disulphide corresponds in composition to carbon
dioxide.
CO2 carbon dioxide.
CS2 carbon disulphide.
It is also analogous to the latter body in its chemical func-
tions. While carbon dioxide combines with metallic oxides,
forming carbonates, carbon disulphide combines with metallic
sulphides, forming sulphocarbonates.
CO² +
Na2O
Na2CO3 corresponding to H2CO3
Sodium oxide. Sodium carbonate.
CS² + Na2S
Carbonic acid
(hypothetical).
Na CSS corresponding to H2CS
Sodium sulphide. Sodium sulphocarbonate.
Sulphocarbonic acid.
Sodium carbonate and sulphocarbonate possess the same con-
stitution. By the action of strong acids they should give anal-
ogous products: the one, carbonic acid, H2CO3; the other,
216
ELEMENTS OF MODERN CHEMISTRY.
sulphocarbonic acid, H2CS³. The latter body is indeed formed
under such circumstances, but normal carbonic acid, if it exist,
possesses no stability, and at once decomposes into carbon diox-
ide and water.
CO + HO
H2CO³ =
Carbon disulphide is employed in the arts in the manufac-
ture of vulcanized caoutchouc, and as a solvent for caoutchouc
in the fabrication of goods impermeable to water by the deposit
of a thin layer of that substance. It is also employed as a
solvent for, and in the extraction of, fats and oils.
CARBON OXYSULPHIDE.
Density compared to air.
Density compared to hydrogen
Molecular weight CSO
2.1046
•
30.4
60.
This body was discovered by de Than in 1867. It is inter-
mediate between carbon dioxide and carbon disulphide.
COO carbon dioxide.
CSO carbon oxysulphide.
CSS carbon disulphide.
Preparation. It is prepared by decomposing potassium sul-
phocyanide by dilute sulphuric acid. Potassium sulphate and
hydrosulphocyanic acid are formed, and, in the presence of an
excess of sulphuric acid and water, the latter decomposes into
ammonia and the gas carbon oxysulphide which may be collected
over mercury; the ammonia remains combined with the sul-
phuric acid in the form of sulphate.
CSNH + H2O
Hydrosulphocyanic acid
NH3 + CSO
Carbon oxysulphide.
Properties. Carbon oxysulphide is a colorless gas, having
an odor like that of carbon disulphide, but also recalling that
of hydrogen sulphide.
On contact with an incandescent body, even a match pre-
senting a spark of fire, it takes fire, burning with a blue flame,
and depositing sulphur if the supply of air be insufficient.
With one and a half times its volume of oxygen it constitutes
an explosive mixture.
2 volumes of carbon oxysulphide
3 volumes of oxygen
2 volumes of carbon dioxide
2 volumes of sulphur dioxide.
CSO mixed with
03 yield
CO2 and
•
SO2
COMPOUNDS OF CARBON AND HYDROGEN.
217
Water dissolves about its own volume of carbon oxysulphide,
but the solution decomposes in a few hours, with the formation
of hydrogen sulphide and carbon dioxide.
CSO + H2O = CO² + H²S
Carbon oxysulphide is absorbed completely, but more slowly
than carbon dioxide, by solutions of the alkaline hydrates; by
a reaction analogous to the preceding, a sulphide and a carbonate
are formed.
COMPOUNDS OF CARBON AND HYDROGEN.
These compounds are numerous and important. Carbon
unites with hydrogen in different proportions, and the atoms of
carbon and hydrogen may accumulate in considerable numbers
in the molecules of their compounds. These combinations are
called hydrocarbons or carbides of hydrogen. Hydrogen mono-
carbide, or marsh gas, contains only one atom of carbon com-
bined with four atoms of hydrogen; its molecule is therefore
represented by the formula CH4. In olefiant gas, or ethylene,
two atoms of carbon are united with four atoms of hydrogen;
in the volatile liquid known as benzine or benzol, which is ob-
tained in large quantities from coal-tar, six atoms of carbon are
combined with six atoms of hydrogen. Lastly, the molecule
of oil of turpentine contains ten atoms of carbon and sixteen
of hydrogen.
Hence these substances give us the following formulæ :
CH¹ methane, or marsh gas.
4
C²H¹ ethylene, or olefiant gas.
C6H6 benzine.
C10H16 turpentine.
These examples, which might be indefinitely multiplied, show:
1st. That the atoms of carbon unite in various proportions with
the atoms of hydrogen to constitute the molecules of the hydro-
carbons. 2d. That they accumulate in greater or less numbers
to form molecules more and more complex, that is, containing
an increasing number of atoms of carbon and hydrogen.
All of these bodies must be considered among the organic
compounds; indeed, the latter are nothing more than the com-
pounds of carbon, and carbon monoxide and dioxide may also
be properly considered as the most simple organic combinations.
K
19
218
ELEMENTS OF MODERN CHEMISTRY.
Hence if the most strictly rigorous method were adhered to,
the description of the compounds of carbon and oxygen would
be followed by that of all the other compounds of this element,
that is, of all the organic compounds. However, for the pur-
poses of study it is advantageous to treat the latter bodies
separately, and they will be so considered in this work. The
following experiments will expose some of the general proper-
ties of the hydrocarbons which have been mentioned :
1. If a lighted taper be applied to a jar of methane, which
is also called marsh gas, because it is disengaged from the muddy
bottoms of marshes, the gas takes fire and burns with a lumi-
nous flame.
2. If the same experiment be repeated with ethylene gas,
which contains for the same proportion of hydrogen twice as
much carbon as marsh gas, a still more luminous flame results.
3. It is well known that benzine and turpentine take fire
when lighted, and burn with bright flames; but it is also known
that their flames are smoky.

FIG. 86.
The hydrocarbons are then
combustible; and how could
they be otherwise, since they
contain only two combustible
elements, carbon and hydro-
gen? The products of the
combustion are water and
carbon dioxide, and the forma-
tion of the latter gas may be
proved by agitating the con-
tents of the jars in which the
combustion has taken place
with lime-water; the latter
immediately becomes milky
by the precipitation of calcium
carbonate.
This combustion is more or
less complete; when the gas or
vapor which burns contains a
large amount of combustible elements, the oxygen of the air
may not be present in sufficient quantity to burn them all, that
is, to oxidize them completely. Under these conditions it is
the hydrogen which is burned by preference, and the carbon
partly escapes combustion.
STRUCTURE OF FLAME.
219
A flame is a gas or vapor in combustion. This combustion
is an oxidation, and it is the oxygen of the air which is the
agent. In order that it may take place, it is generally neces-
sary that the combustible gas shall be brought to a high tem-
perature; but once commenced, the combustion continues of
itself, because the heat disengaged by
the oxidation is sufficient to maintain the
phenomenon. But if a flame be suddenly
cooled, the combustion is at once arrested.
A flame may be cooled by depressing
into it a piece of fine wire gauze.
The
incandescent gases cannot pass through
the meshes of the gauze without being
cooled by contact with the metal, which
is a good conductor of heat. For this
reason, no combustion takes place above
the gauze (Fig. 86).
If a piece of wire gauze be held over
an escaping jet of gas, the latter may be
ignited above the gauze, and will burn
without the combustion being propagated
to the gas below; the gauze acts as a
screen, separating the jet into two portions,
the lower cold and invisible, the upper in
combustion and luminous.
Sir Humphry Davy made a happy ap-
plication of these facts in the construction
of the miner's safety-lamp. This is an
ordinary lamp surrounded by a cylinder
of wire gauze (Fig. 87).
Such a lamp gives less light than one
not protected by an envelope, but it re-
moves the danger of explosions of fire-
damp, for when an explosive mixture is
formed in the galleries of a mine, the gas

FIG. 87.
may penetrate to the interior of the lamp and take fire there,
but the flame cannot pass through the cooling envelope of wire
gauze. The safety-lamps are now constructed with the lower
part of the cylinder of glass, so that there is no diminution in
the amount of light given.
As the oxidation of combustible elements is the source of
heat, it is evident that the different parts of a flame cannot be
220
ELEMENTS OF MODERN CHEMISTRY.
uniformly hot, for the oxygen of the surrounding air cannot
equally attain all portions. The exterior borders are the most
intensely heated; they are surrounded by air, and constitute
the seat of combustion. From them the heat
From them the heat is radiated not
FIG. 88.
only externally, but also to the interior of the
flame, where it produces interesting phenomena.
These may be studied by analyzing a flame,
that is, considering separately the different parts
of which it is composed. If the flame of a can-
dle be examined, it will be found to present three
distinct layers, or cones (Fig. 88).
1. A dark central part, a, which surrounds
the wick. This is known as the obscure cone,
or cone of generation; its temperature is not
high.
2. A luminous part, bb', surrounding the ob-
scure cone. This is the centre from which the
light is emitted. It is known as the luminous
cone, or cone of decomposition.
3. An exterior envelope, cc', thin, and pro-
ducing but little light, yellow towards the sum-
mit, e, and bluish towards the base, dd. It is the
cone of complete combustion, and its temperature
is the highest.
It is easy to account for these phenomena.
The material of the candle is melted by the heat
of the flame, the liquid is drawn up into the
wick by capillarity, and arrives at the incan-
descent summit. There it is decomposed, producing gases and
vapors rich in carbon and hydrogen, and which rise around the
wick, forming an irregular cone. The gaseous products consti-
tuting this cone do not present the same composition through-
out. They have been analyzed by H. Sainte-Claire Deville,
by the aid of very ingenious processes.
The obscure cone is formed of gaseous products holding in
suspension finely-divided carbon, which has not yet arrived at
incandescence.
These products become heated on reaching the more central
portions of the flame. Then the carbon, which is set free by
the decomposition of gases rich in carbon, is brought to bright
incandescence, but it is completely burned only when it reaches
the exterior envelope, where the oxygen is in excess. A simple

STRUCTURE OF FLAME.
221
experiment will demonstrate that the most luminous portion
of the flame holds in suspension finely-divided and incandes-
cent carbon. If a porcelain saucer be depressed into this
portion, the carbon will be deposited on the vessel in the form
of soot.
It is this solid and incandescent carbon which causes the
luminosity of the flame. The flame of hydrogen, which con-
tains only gaseous products, is pale. In the calcium or Drum-
mond light it produces great brilliancy because a solid body,
lime, is heated to bright incandescence. When the carbon
suspended in a flame is in excess in proportion to the supply
of oxygen, it is incompletely burned, and is carried into the
air. The flame then smokes.
At the base of the cone, carbon monoxide and methane, the
first products of the decomposition of the candle, burn on con-
tact with the air at dd' with a bluish flame.
According to recent experiments, the density of a burning
gas is not without influence upon the lustre of the flame. The
flame of hydrogen is luminous when that gas is burned under
strong pressure (Frankland).
Illuminating gas is a mixture of hydrogen with various gas-
eous hydrocarbons and a small proportion of carbon monoxide.
It is manufactured by the destructive dis-
tillation of bituminous coal. The aqueous
products containing ammonia, and the
tarry matters formed during the distilla-
tion are condensed, and the gas is purified
by washing with water and passage over
slaked lime to remove sulphur and other
impurities.

KAIR
Illuminating gas forms an explosive
mixture with air, but if the mixture be
burned as it is formed, the resulting flame.
will be almost colorless and will deposit
no soot, the whole of the carbon coming
in contact with sufficient oxygen for its
complete combustion. These conditions
are fulfilled in the Bunsen burner (Fig.
89). In this burner, the force of the
escaping gas-jet draws in air through holes
site the jet in a wider tube, at the end of which the mixture is
burned.
GAS
FIG. 89.
immediately oppo-
19**
222
ELEMENTS OF MODERN CHEMISTRY.
GENERAL NOTIONS UPON THE METALLOIDS.
THEORY OF ATOMICITY.
From a consideration of the facts acquired in the study of
the elements known as metalloids, we may deduce certain gen-
eral consequences, and while looking back on the field over
which we have passed, we may at the same time fix certain
landmarks for the remainder of our course.
The elements which we have studied are not alike in their
aptitude to enter into combination, nor in the general characters
of their compounds. In this respect, analogies and differ-
ences have been established between them, and these have
become the basis of a rational classification. Following the
example of Dumas, we have arranged these elements in groups
or families, uniting in the same group those which are related
by their chemical functions. For this reason boron has been
separated from silicon and carbon, since it differs from them
so far as concerns the composition of their compounds. The
groups thus formed are as follows:
HYDROGEN.
OXYGEN.
SULPHUR.
FLUORINE.
SELENIUM.
CHLORINE.
TELLURIUM.
BROMINE.
NITROGEN.
PHOSPHORUS.
ARSENIC.
ANTIMONY.
BORON.
SILICON.
CARBON.
IODINE.
In order to account for the chemical functions of all these
bodies, that is, for the parts which they play in their combina-
tions, we must first consider their hydrogen compounds. They
constitute the following series:
HH
Hydrogen.
H2O
Water.
HCI
Hydrochloric
acid.
H2S
Hydrogen
sulphide.
H³N
Ammonia.
H³P
Hydrogen
H'Si
Hydrogen silicide.
H&C
Hydrogen
phosphide.
carbide.
HBr
Hydrobromic
acid.
HI
H2Se
H'As
Hydrogen
Hydrogen arsenide.
selenide.
H2Te
H3Sb
Hydriodic acid.
HFI
Hydrofluoric acid.
Hydrogen Hydrogen antimonide.
telluride.
THEORY OF ATOMICITY.
223
It is seen that the preceding groups are characterized by the
composition of their hydrogen compounds. While the bodies
of the first group combine with hydrogen atom for atom, those
of the second group require two atoms of hydrogen, those of
the third three, and those of the fourth four, to form hydrogen
compounds. Hence we may draw the conclusion that the atoms
of these metalloids are far from being equivalent in their power
of combination with hydrogen.
The atoms of chlorine, bromine, and iodine are equivalent
to each other in this respect, for each requires but one atom
of hydrogen.
The atoms of oxygen, sulphur, etc., are equivalent to each
other, for each combines with two atoms of hydrogen.
The atoms of nitrogen, phosphorus, arsenic, and antimony
are equivalent to each other, for each of them unites with three
atoms of hydrogen.
Lastly, the atoms of carbon and silicon are equivalent, for
each can unite with four atoms of hydrogen.
But, on the other hand, it is evident that the atoms of chlo-
rine, oxygen, nitrogen and carbon are not equivalent to each
other, as regards their power of combination with hydrogen,
since each of them unites with a different number of atoms of
that body.
In this respect it may be said that
1 atom of chlorine is equivalent to 1 atom of hydrogen.
1 atom of oxygen
1 atom of nitrogen
1 atom of carbon
(6
2 atoms
3 atoms
4 atoms
65
It is evident that the capacity of combination which resides
in the atoms of simple bodies and by which they attract the
atoms of hydrogen, is unequal. Leaving aside its intensity,
this force is exerted in different degrees, for it determines the
union of 1 atom of chlorine, oxygen, nitrogen, or carbon, with
1, 2, 3, or 4 atoms of hydrogen.
This number of hydrogen atoms is the measure of the degree
of force which resides in the atoms, of the capacity of combi-
nation which they possess for each other.
Hence we conclude that
The atoms of chlorine and its associates are monatomic or univalent.
The atoms of oxygen
The atoms of nitrogen
The atoms of carbon
diatomic or bivalent.
triatomic or trivalent.
tetratomic or quadrivalent.
224
ELEMENTS OF MODERN CHEMISTRY.
The capacity of combination which resides in the atoms, and
which is exerted in such different manners according to the
nature of the atoms, is called atomicity. Atomicity is the
relative equivalence of the atoms; it is simple or multiple, and
if we consider it in its first degree, we may say that the atoms
of chlorine and the atoms of hydrogen are so constituted that
a single atom of one attracts a single atom of the other. When
they combine, they exchange in some manner a unit of satura-
tion, and in the combination of chlorine and hydrogen two of
these units of force are neutralized; two units of saturation or
two atomicities are exchanged: the atoms of chlorine and of
hydrogen are univalent.
The force which resides in an atom of oxygen is more com-
plex. It attracts two atoms of hydrogen, and represents the
second degree of capacity of combination, and we may say that
in each atom of oxygen reside two atomicities, which are satis-
fied and exchanged when this atom combines with two atoms of
hydrogen. Hence, four atomicitics are satisfied by the com-
bination.
Following the same reasoning, we consider that a triple capa-
city of combination is active in an atom of nitrogen when this
atom unites with three atoms of hydrogen; and that six atom-
icities are satisfied by the combination.
Lastly, tetratomic carbon is provided with four atomicities,
which are satisfied by the four atomicities which reside in four
atoms of hydrogen.
If this neutralization or exchange of two units of saturation
be represented by a hyphen, we will have the following formula:
H-CI
Hydrochloric acid.
H-O-H
Water.
H
N
H H
Ammonia.
H
H-C-H
H
Hydrogen monocarbide.
It is seen that in the formula for water, ammonia and hydro-
gen monocarbide, the polyatomic elements, oxygen, nitrogen
and carbon, constitute, as it were, the nuclei around which the
other atoms are symmetrically grouped.
A great many other bodies present the same constitutions as
the preceding; it is evident that a given element in any com-
pound may be replaced by another element having the same
atomicity, without disturbing the equilibrium of the atomicities.
THEORY OF ATOMICITY.
225
Indeed, if we suppose the chlorine, oxygen, nitrogen, and
carbon to be replaced by elements of corresponding atomicities,
we will have the series of hydrogen compounds already con-
sidered. All of the bodies which are classed together in the
series belong to the same type. Each contains an equal num-
ber of atomicities for the same number of atoms.
According to the principle of substitution announced above,
it is evident that the hydrogen in each of the hydrogen com-
pounds under consideration may be replaced by another mon-
atomic element, and the compounds thus formed will still belong
to the primitive types.
So considered, a great number of compounds possess the
same constitution, that is, the same molecular structure,-
as hydrochloric acid, water, ammonia, and methane or hydro-
gen monocarbide. Such are those arranged in vertical columns
in the following table:
TYPE HCI
Cl-Cl
Free chlorine.
TYPE H20
H-O-H
TYPE NH3
K
TYPE H4
Cl
Water.
-Z
N
CI-C-CI
H H
Cl
Potassium amide.
Carbon tetrachloride.
K-CI
Potassium chloride. Hypochlorous oxide.
Cl-O-CI
Cl
Cl
|
Р
Cl-Si-Cl
Cl
Cl Cl
Phosphorus trichloride. Silicon tetrachloride,
K-I
H-O-K
Cl
Potassium iodide.
Potassium hydrate.
Sb
Ag-O-Ag
Cl Cl
H
H-Si-H
H
Ag-I
Silver iodide.
Silver oxide. Antimony trichloride. Hydrogen silicide.
All of these bodies belong to the respective types HCI, H2O,
NH³, CH, the first three of which were established by Ger-
hardt, and have their existence explained by the atomicity of
the elements; that is, by the varying equivalence of their atoms,
measured, in the present examples, by the number of hydrogen
atoms with which they combine.
One atom of oxygen is equivalent to two atoms of hydrogen
K*
226
ELEMENTS OF MODERN CHEMISTRY.
or two atoms of chlorine. Hence, in the preceding combina-
tions, two atoms of chlorine may be replaced by one atom of
oxygen without changing the equilibrium of the atomicities.
Thus, the oxides SiO2, CO², correspond to the chlorides SiCl*,
CCI, and belong to the same type. The four atomicities of
an atom of silicon or carbon are saturated by the four atomici-
ties of two atoms of oxygen.
The trichlorides of phosphorus and antimony, PCI³ and SbCl³,
which will be found in the preceding table, require an impor-
tant remark. They are not saturated with chlorine, and each
may combine with two more atoms of that element, producing
the compounds PC and SbC15.
Thus, while phosphorus exhausts its power of combination
with hydrogen in uniting with three atoms of that element in
PH³, its capacity of combination with chlorine is only exhausted
when it has combined with five atoms; while it plays the part
of a triatomic element in hydrogen phosphide, it is pentatomic.
in phosphorus pentachloride.
From these facts it follows that it is often difficult to meas-
ure in an absolute manner the capacity of combination which
resides in an atom; for that capacity varies according to the
nature of the elements upon which it is exerted. Affinity is
an elective force. A given element does not attract all of the
other elements with equal facility; it selects certain ones by
preference, and neglects the others. With one, it may form
but a single compound; with another, it may form several.
Nitrogen forms with hydrogen but one combination, ammo-
nia, NH³, which cannot fix any more atoms of hydrogen. Sat-
urated with hydrogen in ammonia, nitrogen manifests in con-
tact with that element but three atomicities. But let ammonia
be brought in contact with a body other than hydrogen, hydro-
chloric acid, for example, and it will combine with it, forming
ammonia hydrochloride, or ammonium chloride. If its ca-
pacity of combination is exhausted for hydrogen, HH, it is
not exhausted for hydrogen combined with chlorine, HCl.
Thus, an atom of nitrogen possesses other affinities than those
which it manifests for hydrogen in ammonia. While nitrogen
is triatomic in ammonia because it is united with three mon-
atomic atoms, it behaves as a pentatomic element in ammonium
chloride.
The parts which polyatomic elements play in their compounds
may be expressed by accents marking the number of atomici-
THEORY OF ATOMICITY.
227
ties or the quantivalence of the element, as shown in the
following formula:
O"H" N""'H³ N°H⭑Cl PC13
Water. Ammonia. Ammonium Phosphorus
chloride. trichloride.
PVC'15 ClivO"2
Phosphorus
pentachloride. dioxide.
Carbon
In these compounds, as has been remarked before, the poly-
atomic elements form, as it were, the nuclei around which the
other elements are grouped. This is an important idea, since
it leads to the determination of the constitution of the mole-
cules, that is, the arrangement of their atoms. The considera-
tions just presented concerning the functions of the elements
in compounds alone permit the resolution of this question;
they alone lead to the discovery of the relations existing be-
tween the atoms in their combinations, and to the determina-
tion of their relative positions, in a word, to the revelation of
the molecular structure.
The following developments will demonstrate this fact.
We will reconsider certain of the combinations above men-
tioned, which have been taken as types.
In water, an atom of diatomic oxygen fixes two atoms of
hydrogen. One atom of oxygen can fix two atoms of any
monatomic element, forming compounds belonging to the same
type as water; but it cannot at the same time fix a monatomic
element and a diatomic element. In other words, an atom of
hydrogen in water may be replaced by an atom of chlorine,
bromine, iodine, or potassium, but not by an atom of oxygen;
and if a second atom of the latter element be joined to the
oxygen of water, it will be seen that there remains a free affin-
ity which may be satisfied by hydrogen. Hydrogen dioxide
would result.
H-O"-H
Water.
H-O"-0″-H
Hydrogen dioxide.
Hence, we draw the conclusion that in hydrogen peroxide,
the two atoms of oxygen are combined with each other, and
that in uniting together each atom loses one atomicity, the two
others being satisfied by hydrogen.
The same considerations are applicable to the compounds of
chlorine and oxygen.
Hypochlorous acid may be regarded as composed of an atom
of chlorine united to the group hydroxyl.
CI-O"-H CI(OH)'
Hypochlorous acid.
228
ELEMENTS OF MODERN CHEMISTRY.
In this compound the chlorine exchanges one unit of satu-
ration with the oxygen of the group OH, just as it exchanges
one with hydrogen in hydrochloric acid: it is monatomic or
univalent. In chloric acid it is combined with two atoms of
oxygen and one group, OH. It exchanges 4 atomicities with
oxygen, and one with the group OH :
CIVO"2(OH)
Chloric acid.
Chlorine thus manifests 5 atomicities in chloric acid; but it
has 7 in perchloric acid.
Clvii O³(OH)'
Perchloric acid.
Without dwelling on these considerations, we will take one
more example.
In hydrogen phosphide, one atom of phosphorus is combined
with three atoms of hydrogen; it manifests but three atomici-
ties, and these could not neutralize those which reside in three
atoms of oxygen, since the latter possess six atomicities. If,
then, three atoms of diatomic oxygen were united with one
atom of triatomic phosphorus, it is clear that three affinities
would remain free, one in each of the three atoms of oxygen.
In phosphorous acid, these three affinities of the oxygen atoms
are satisfied by three atoms of hydrogen. We may suppose
that in the molecule of this compound, the phosphorus is the
nucleus around which are grouped three atoms of oxygen, each
of which is joined also to one atom of hydrogen.
This atomic grouping is indicated in the following formula:
H
P
H H
Hydrogen phosphide.
OH
I
Р
HO OH
Phosphorous acid.
This hydrogen, combined with the oxygen in all of the oxy-
gen acids, plays invariably the same part: it saturates the one
atomicity which remains free in one atom of oxygen. The
oxygen thus combined with an atom of hydrogen, has lost one
of its atomicities by the fact of this combination; it still retains
one in the group OH, which represents, as it were, water less
one atom of hydrogen.
HOH — H = (OH)'
THEORY OF ATOMICITY.
229
This group is named hydroxyl, and it is evident that,
although it cannot exist by itself, it may play the part of a
monatomic element, for it retains one free atomicity. It may
then replace a monatomic element, such as hydrogen or chlo-
rine. Indeed, it plays an important part in the constitution of
acids.
If we consider the examples which have already been dis-
cussed, we will notice that it is this hydroxyl which, by com-
bining with an element or group of elements capable of forming
acids, confers upon them the characters of acids. So consid-
ered, hypochlorous acid is formed by the union of hydroxyl
with an atom of chlorine.
CI(OH)'
Hypochlorous acid.
Sulphuric acid is formed by the union of two hydroxyl groups
with sulphurous oxide, and represents in a manner sulphuryl
chloride in which the two atoms of chlorine are replaced by
two hydroxyl groups.
Cl
so² { a
Sulphuryl chloride.
SO2
S (OH)
(OH)
Sulphuric acid.
Phosphorous acid is formed by the union of three hydroxyl
groups with one atom of phosphorus.
CI
P CI
( CI
Phosphorus trichloride.
(OH)
P''' ' · (OH)'
(OH)'
Phosphorous acid.
Lastly, phosphoric acid results from the union of three hy-
droxyl groups with one atom of phosphorus already combined
with one atom of oxygen (phosphoryl).
CI
O'P Cl
CI
Phosphoryl trichloride.
{
(OH)
O"P" (OH)'
(OH)'
Phosphoric acid.
Such, according to the theory of atomicity, are the relations
existing between the atoms of certain acids; such, in other words,
is the constitution of these acids. It would be easy to extend
these considerations to other bodies, but the examples we have
chosen are sufficient to indicate the importance of the idea of
atomicity, when it is applied to the discovery and definition of
20
230
ELEMENTS OF MODERN CHEMISTRY.
the part played by each element in a given compound. By
supposing the capacities of combination of chlorine, oxygen,
sulphur, and phosphorus to be known, we have been able to
follow these bodies in their most important combinations, we
have seen how they attract and group around themselves other
elements. We have thus been able to penetrate the atomic
structure of the molecules, and have built up as it were the
molecular edifice. It must be remembered, however, that the
preceding formulæ do not in any manner represent the real
positions of the atoms in space. Their sole object is to indi-
cate the points of attachment of the affinities, and consequently
the mutual relations between the atoms.
METALS.
THE metals are elements which are good conductors of heat
and electricity, and are endowed with a peculiar lustre, which
is called the metallic lustre. This definition, it will be ob-
served, is founded upon certain physical characters rather than
upon chemical properties. It is unsatisfactory and wanting in
exactness, for it is applicable to bodies which are properly con-
sidered as metalloids. Such is antimony, which has already
been described, and bismuth, which should be placed beside
antimony. Indeed, the distinction between the metals and
metalloids is not so well marked that a line which shall sepa-
rate these two classes of simple bodies may be sharply drawn.
Physical Properties of the Metals.-These will be found
in the table on page 232, but the indications there given may
be completed by certain other developments.
The metals are opaque, but their opacity is not absolute.
A sheet of gold-leaf pressed out between two plates of glass
allows the passage of a green light.
Gold possesses a brilliant lustre and a yellow color, but it
loses this lustre when it is reduced to a minute powder. When,
however, this powder is rubbed with a hard body, when, for
example, it is triturated in an agate mortar, or passed under
the burnisher, it acquires a certain degree of cohesion, and
again assumes its lustre.
It is thus with all the metals. They lose their metallic lustre
when finely divided and reassume it on burnishing.
The yellow color of gold is not its true color; the rays which
reach the eye are the result of but one reflection, but if light
be successively reflected from ten surfaces of gold, the metal
will appear of a bright-red color. Under the same circum-
stances, copper will appear scarlet, zinc indigo, iron violet, and
silver pure yellow (B. Prevost).
Most of the metals may be crystallized. Bismuth is the
most striking example. If a few kilogrammes of pure bismuth
be fused, and the liquid mass be allowed to cool slowly, the
231
232
ELEMENTS OF MODERN CHEMISTRY.

DENSITY.
FUSING POINTS.
(Centigrade.)
CONDUCTI-
BILITY
for HEAT.
TENACITY EX-
PRESSED IN THE
NUMBER OF KILO-
GRAMMES NECES-
SARY TO BREAK A
WIRE 2 MILLIME-
TRES IN DIAM-
ETER.
HARDNESS.
Order of
SPECIFIC HEATS.
MALLEA-
Order of
DUCTILITY.
BILITY.
Platinum
Osmium
Gold (cast)
Mercury {
Palladiuni
{
S rolled.
cast
•
23.00 Mercury
390 Silver
1000 Potassium 0.1691 Gold.
21.15 Potassium
•
•
+6205 Copper
736 Iron
0.1138 Silver.
Gold.
Silver.
Iron
249.659 Manganese
Copper 137.399 Chromium
}scratch glass.
21.40 Sodium
95°6 Gold
532 Nickel
0.1086 Aluminium. Platinum.
Platinum 124.690
•
19.35 |Tin
2290 Zinc
193 Cobalt
•
•
0.1070 Copper.
Aluminium. Silver
85.062 Nickel
•
•
Lead (cast)
Silver (cast)
Bismuth (cast)
9.82
sol. at -420 14.40
liq. at 0° 13.59 Lead
11.80
11.33 Zinc
10.57 Antimony.
Aluminium,
Bismuth
2640 |Tin
145 Zinc
•
0.0955|Tin.
Iron.
Gold
68.216 Cobalt
3350 Iron
•
119 Copper
0.0951 Platinum.
Nickel.
Zinc
49.790 Iron
•
•
scratched by
glass.
Cadmium
•
360° Lead
410 Platinum
4500 Bismuth
85 Palladium 0.0593 Lead.
Copper.
Nickel
47.676 Antimony
•
Nickel
8.82
about
7500
•
84 Cadmium 0.0562 Zinc.
0.0562|Iron.
18 Tin
Silver
Antimony 0.0508
Zinc.
Tin
15.740 Zinc
Tin.
Lead
9.555
0.0570 Nickel.
Lead.
Palladium
Platinum
Copper (cast)
8.79
Silver (high
Mercury 0.0333
Cadmium
8.60
red)
10000
Gold
0.0324
•
Cobalt (cast)
7.79 Copper.
11000
Platinum 0.0324
Copper
Gold.
scratched by
Silver
carbonate of lime.
Bismuth
Iron
{
S malleable
7.79 Gold, about
12500
Lead
0.0314
cast
7.25
cast.
12500
Tin (cast).
Manganese
7.20
Chromium
7.29 Iron soft (white
7.01 Nickel and co-
heat) 15000
Zinc (cast)
6.86
balt, about. 1600°
Antimony
6.71
Platinum, about 2000°
Aluminium
2.56 |Iridium, about 25000
Sodium
Potassium
0.97
•
0.855
Lithium
0.59
Cadmium
Tin
Lead, scratched by the nail.
Potassium soft at ordinary
Sodium S temperatures.
Mercury, liquid at ordinary tem-
peratures.


GENERAL PROPERTIES OF METALS.
233
metal will solidify first next to the walls of the vessel and on
the surface, where it is most cooled. If, in a little while, the
crust which covers the still liquid metal be pierced, and the
latter be poured out, the whole of the interior of the vessel
will be found covered with magnificent crystals, arranged in
hopper-like pyramids, and presenting brilliant, rainbow-like
colors.
Other metals, such as copper, lead, antimony, tin, silver, and
gold, may be crystallized under certain conditions. Some of
the metals are found crystallized in nature.
Those metals which may be beaten or rolled into thin laminæ
are said to be malleable. AA (Fig. 90) represent two steel
B
B

ונ
A
A
Ta
FIG. 90.
rollers capable of moving on their axes in opposite directions.
A plate of metal engaged between them will be drawn in, and
the rolled sheet will pass out on the other side with a uniform
thickness equal to the distance between the two rollers. By
diminishing this distance more and more by means of the
screws BB, the sheet may gradually be reduced in thickness.
Metals which may be drawn out into wires are said to be
ductile. The wire-drawing machine is represented in Fig.
91. It consists of a steel plate, ff, firmly fixed in the up-
rights CC, which are themselves solidly attached to a bench.
The plate is pierced with a series of holes regularly decreasing
in diameter. The wire is drawn from the bobbin A, through
the holes and around the cylinder B, which is moved by power.
That a metal may be drawn into fine wires, it is necessary
that it shall offer a certain resistance to rupture. This is called
the tenacity of the metal. It is measured by suspending weights
20*
234
ELEMENTS OF MODERN CHEMISTRY.
at the extremities of wires of the same diameter. Iron is the
most tenacious of metals.
All of the metals are fusible. Some of them are volatile
and may be distilled; among the latter are mercury, potassium,
sodium, zinc, and cadmium. All of the metals are insoluble.
Chemical Properties of the Metals. The metals combine
with each other and with the metalloids, the energy with which
these combinations take place being very variable. In general,

A
B
C
FIG. 91.
the metals having the strongest affinities are those known as the
alkaline metals, because they are obtained from the alkalies.
Such are potassium and sodium.
All of the metals combine directly with chlorine. The chlo-
rides thus formed do not all possess the same composition; they
contain for one atom of metal a varying number of chlorine
atoms.
A similar remark applies to the oxides and sulphides formed
by the union of oxygen and sulphur with the metals. The
power of combination of the latter with chlorine, sulphur, oxy-
gen, etc., is far from being the same. In other words, the atoms
of the metals combine unequally with the atoms of chlorine,
oxygen, etc.; hence it follows that the atomic composition of
the bodies thus formed is different. If the metals be compared
together in this respect, analogies and differences will be estab-
lished between them, which become the basis for a rational
classification. Those metals which form compounds having
EXTRACTION OF METALS.
235
analogous atomic constitutions are put into the same group.
Such principles as these have guided us in the classification of
the metalloids, and we will apply them to the metals as soon as
we have acquired a general knowledge of their compounds.
Thenard founded a classification of the metals, not upon their
power of combination considered in a general manner, but upon
the variable energy of their affinities for oxygen. He measured
this affinity:
1. By the facility with which the metals attract free oxygen
at various temperatures.
2. By the difficulty with which the oxides, once formed,
abandon their oxygen.
3. By the greater or less energy with which the metals de-
compose water.
Following these principles, Thenard divided the metals into six
classes. It cannot be denied that this classification presents many
practical advantages, but, on the other hand, in a great num-
ber of cases it does not recognize the best established analogies.
Natural State and Extraction of the Metals.-Certain
metals are found in nature free from all combination. It is
thus that gold, silver, copper, bismuth, etc., are met with in
the native state.
More often the metals are found combined with oxygen, sul-
phur, or other metalloids. The natural sulphides are numerous
and abundant: those of silver, copper, mercury, lead, and zinc
constitute the minerals from which these metals are ordinarily
extracted.
Iron and tin are obtained from their oxides, which are found
in nature.
The metals are often found in saline combinations, in the form
of chlorides, carbonates, sulphates, phosphates, and silicates.
We can only indicate here in a very general manner the
methods by the aid of which the metals are extracted from
their combinations.
If a metal is to be obtained from its oxide, the latter is
reduced by charcoal at a high temperature.
If the ore be a sulphide, it is first roasted, that is, heated in
contact with the air. The oxygen of the air then acts upon
the sulphur, which is disengaged in the form of sulphurous
oxide, and upon the metal, which remains in the form of oxide;
the latter is afterwards reduced by charcoal.
The metals are sometimes obtained from their chlorides by
236
ELEMENTS OF MODERN CHEMISTRY.
*
heating the latter with sodium, which combines with the chlo-
rine, forming sodium chloride.
ALLOYS.
The combinations of the metals with each other are called
alloys; amalgams are the alloys formed by mercury. These
combinations take place with the production of heat.
If a small quantity of mercury be heated in a crucible or a
capsule, and a morsel of sodium be thrown into it, the latter
dissolves instantly with a hissing noise, which indicates the
disengagement of heat.
By employing the proper proportions of mercury and so-
dium, the alloy may be obtained in crystals possessing a definite
composition.
Crystalline combinations of zinc and antimony are known.
The most interesting, Sb2Zn³, contains two atoms of antimony
for three atoms of zinc.
It is necessary to state that more generally the alloys do not
present the characters of definite compounds. The metals seem
to alloy each other in all proportions, forming mixtures which
are more or less homogeneous; but this is only in appearance,
and it must be admitted that one or more compounds exist in
such a mixture, remaining dissolved in each other, or mixed
with the excess of one of the metals. Such a mixture would
form a sensibly homogeneous mass, especially when the molten
mixture had been suddenly cooled. But if the cooling be slow,
it may happen that the less fusible definite compounds separate
from the mixture in the crystalline form, leaving the more
fusible compounds which still remain liquid. Such a separa-
tion often takes place in large masses of melted alloys which
are allowed to cool slowly. The process is called liquation,
and it may be readily conceived that the alloys so cooled are
far from homogeneous in composition after their solidification.
Reciprocally, when a mass composed of a mixture of metals
and alloys is slowly heated, the more fusible assume the liquid
state first, and separate from the others.
This difference between the fusing-points of the various defi-
nite compounds which may exist in an alloy is taken advantage
of in the arts for their separation.
Alloys are always more fusible than the most fusible of their
component metals.
ALLOYS.
237
There is an alloy which is fusible between 66 and 71°; it is
formed of
Cadmium
Tin
Lead
Bismuth
•
1 to 2 parts.
2 parts.
4 parts.
7 to 8 parts.
This is known as Wood's alloy. The fusible metal of Arcet
is composed of
Bismuth
Lead
Tin
8 parts.
5 parts.
3 parts.
It melts at 94.5°. The following table gives the composition
of the principal alloys:
Gold coin
•
Gold jewelry.
Silver coin
Silver plate
Silver jewelry .
Bronze medals
Gun-metal. .
Bell-metal
•
Speculum-metal
Aluminium bronze
Red brass
White brass
German silver
Type-metal
Britannia-metal
Copper
Silver
Copper
Silver
·
Copper
Silver
Copper
Copper
Tin
Zinc
Copper
Tin
Copper
Tin
Copper
Tin
Copper
Aluminium
•
•
•
•
Copper
Zinc
Copper
Zinc
Copper
Zinc
Nickel
Lead.
Antimony
Tin
Antimony
Bismuth
Copper
Gold
{ Copper
Gold
900
100
750-920
250-80
900
100
950
50
800
200
•
93.5-95
•
6-4
. 0.5-1
100
10
78
22
67
33
90-95
10-5
•
90
10
65
35
50
25
+
•
25
80
20
100
•
•
8
1
4
•
Tin
92
Hard pewter
Lead
8
•
Soft pewter
(Tin
82
•
Lead
18
•
Tin
66
Plumbers' solder.
Lead
33
238
ELEMENTS OF MODERN CHEMISTRY.
METALLIC OXIDES AND HYDRATES.
Formation of Metallic Oxides.—The metals absorb oxygen
with very unequal energy. Many of them become oxidized
when exposed to the air at temperatures more or less elevated.
In this respect it is important to distinguish the action of dry
air from that of moist air.
Potassium is the only metal that absorbs dry oxygen at ordi-
nary temperatures. All of the other metals, with the excep-
tion of silver, gold, and platinum, only become oxidized in the
air at very high temperatures. Melted lead absorbs oxygen.
Mercury becomes oxidized at about 350°; copper at a dull-red
heat.
The combination often takes place with the production of
luminous heat. Iron burns in oxygen, but it is necessary that
the metal be first heated to bright redness that the combustion
may take place.
However, the finely-divided iron that is obtained by reducing
oxide of iron in a current of hydrogen at a comparatively low
temperature, will take fire when exposed to the air at ordi-
nary temperatures. It is pyrophoric, and the fine state of
division of the metal favors the oxidation. If the powder be
projected into the air, each particle takes fire and burns with a
bright flash.
A bright sheet of iron will indefinitely preserve its brilliant
surface in dry air, but if a drop of water be placed upon it, or
if it be exposed to the action of a moist atmosphere, rust makes
its appearance in a short time. This rust is ferric hydrate,
for the metal has at the same time absorbed oxygen and
water.
It is generally admitted that it is the oxygen of the air dis-
solved in the water that first fixes upon the metal, and that
the combination is favored by the presence of carbon dioxide.
However it may be, the spot of rust once formed constitutes a
Voltaic couple with the iron itself, and the current so estab-
lished decomposes the water. The oxidation then proceeds.
rapidly, the oxygen of the decomposed water combining with
the metal.
It is possible that hydrogen dioxide may play a part in oxi-
dations; it may be formed as a secondary product during the
METALLIC OXIDES AND HYDRATES.
239
decomposition of the water, and fix directly upon the metals,
converting them into hydrates (Weltzien).
Fe² + 3H2O²
Iron.
Hydrogen dioxide.
Fe2O6H6
Ferric hydrate.
Mg + H202
Magnesium.
MgO²H²
Magnesium hydrate.
Indeed, the oxidation of metals in moist air always produces
hydrates and not oxides.
Composition and Classification of the Oxides.-It has
already been remarked that the metals differ as to the number
of oxygen atoms with which they combine; besides this, the
same metal may form several compounds with oxygen; differ-
ent degrees of oxidation. Hence the oxides present different
compositions, and the differences are important, since they exer-
cise a marked influence upon the properties of the compounds.
1. Certain oxides present the same atomic constitution as
water. Two atoms of metal are combined with one atom of
oxygen.
K20 potassium oxide.
Na20 sodium oxide.
Li20 lithium oxide.
T120 thallium oxide.
Ag20 silver oxide.
2. One atom of certain metals can combine with one atom
of oxygen; the oxides of the gencral formula MO result.
BaO barium oxide.
SrO strontium oxide.
CaO calcium oxide.
MgO magnesium oxide.
MnO manganous oxide.
FeO ferrous oxide.
ZnO zinc oxide.
PbO lead oxide.
CuO cupric oxide.
HgO mercuric oxide.
SnO stannous oxide.
The metallic oxides containing but one atom of oxygen are
generally energetic bases; that is, they react energetically with
the acids, forming salts. They are sometimes called basic oxides.
3. The sesquioxides are those which contain two atoms of
metal and three atoms of oxygen. Such is antimony oxide,
that has already been studied; the oxides of bismuth, gold, etc.,
present an analogous composition.
240
ELEMENTS OF MODERN CHEMISTRY.
Sb2O3 antimony sesquioxide.
B1203 bismuth sesquioxide.
Au203 gold sesquioxide.
Fe203 ferric oxide.
Mn203 manganic oxide.
C1203 chromic oxide.
A1203 aluminium oxide.
4. A large number of oxides contain two atoms of oxygen.
Ba02 barium dioxide.
Sr02 strontium dioxide.
MnO2 manganese dioxide.
Pb02 lead dioxide.
SnO2 stannic oxide.
The first four dioxides are incapable of uniting with acids to
form corresponding salts. Dumas called them singular oxides.
When manganese dioxide is heated with sulphuric acid, oxygen
is disengaged, and manganous sulphate is formed, which corre-
sponds not to the dioxide, but to manganous oxide.
H2SO4 + MnO2
MnSO4 + H²0 + 0
Sulphuric acid. Manganese dioxide. Manganous sulphate.
Under the same circumstances, the other singular oxides act
in the same manner.
As to stannic oxide, it is the anhydride of a metallic acid.
SnO2 + H2O
H2SnO³
Stannic acid.
5. The oxides which contain three atoms of oxygen possess
acid characters still more marked than stannic oxide.~ Man-
ganese trioxide, MnO³, is known. Ferric and chromic anhy-
drides present the same composition.
MnO3 manganese trioxide, or manganic anhydride.
Cro³ chromium trioxide, or chromic anhydride.
Fe03 iron trioxide, or ferric anhydride.
6. There is a class of oxides still more complex than the
preceding; they can be regarded as formed by the union of
two oxides, and they have been named saline oxides. Such are
Manganoso-manganic oxide Mn304
manganese.
Diplumboso-plumbic oxide Pb304
Mn2O3 + Mn0, or red oxide of
Pb0² + 2Pb0, or red oxide of lead.
The first contains one molecule of a sesquioxide, combined
with one molecule of a monoxide; the second, one molecule of a
dioxide and two molecules of a monoxide.
METALLIC OXIDES.
241
Chemical Properties of the Oxides.-Some of the oxides
are fixed, that is, undecomposable by heat; others lose the
whole or a part of their oxygen at temperatures more or less
elevated. The oxides of the noble metals, such as silver, gold,
and platinum, are decomposed by heat alone into metal and
oxygen. We have seen that mercuric oxide is decomposed by
a dull-red heat. Many of the oxides that contain two or three
atoms of oxygen lose a part of the latter element when heated
to redness. Such are the dioxides of manganese, lead, and
barium.
The oxides containing but one atom of oxygen are among
the most stable. Some of them absorb oxygen when they are
heated in contact with air, forming higher oxides. Among
these are manganous, ferrous, plumbous, and stannous oxides.
Hydrogen reduces the greater number of the oxides at tem-
peratures more or less elevated; water is formed, and the metal
is set at liberty.
If a current of dry hydrogen be passed over ferric oxide
heated in a glass bulb (Fig. 92), the oxide is reduced, and a

FIG. 92.
black powder is obtained which is finely divided and pyropho-
ric iron. Vapor of water escapes at the same time by the
drawn-out point of the bulb.
Fe²0³
+ 3H2
3H2O + 2Fe
Ferric oxide.
Iron.
L
21
242
ELEMENTS OF MODERN CHEMISTRY.
The ferric oxide may be replaced by cupric oxide, CuO. If
this oxide be heated in a current of hydrogen, it is reduced,
and the action is so energetic that it gives rise to the produc-
tion of luminous heat.
Carbon reduces the greater number of the oxides with for-
mation of either carbon dioxide or monoxide. It is even more
energetic in its action than hydrogen, for it decomposes oxides
which are irreducible by the latter element, such as those of
potassium and sodium. The oxides of calcium, barium, stron-
tium, magnesium, and aluminium are irreducible by carbon.
The other oxides require for reduction a temperature more or
less elevated, according to the force with which they retain
their oxygen. If the reduction be difficult, a high temperature
is required, and carbon monoxide is formed; otherwise carbon
dioxide is the product.
A small quantity of cupric oxide may be reduced by char-

FIG. 93.
coal by heating the mixture in a glass tube by the aid of a
spirit-lamp (Fig. 93). Carbon dioxide is disengaged.
2CuO + C
Cupric oxide.
2Cu + CO²
Copper.
But to reduce zinc oxide by charcoal, the mixture must be
METALLIC OXIDES.
243
heated to bright redness in a clay or iron retort, and in this
case carbon monoxide is evolved.
ZnO + C Zn + CO
Zinc oxide.
Zinc.
Chlorine decomposes nearly all of the oxides at a high tem-
perature. It drives out the oxygen and combines with the
metal, forming a chloride. Some of the oxides are irreducible
by carbon, and resist also the action of chlorine. Such an
oxide is aluminium oxide, or alumina. But if these oxides
be submitted to the simultaneous action of chlorine and carbon
at a high temperature, they are converted into chlorides, and
carbon monoxide is disengaged.
An intimate mixture of alumina and charcoal may be intro-
duced into a porcelain tube, BB (Fig. 94), which is heated to

~TEDADL
B
FIG. 94.
bright redness, and a current of dry chlorine then passed
through. In this case, carbon monoxide is disengaged, while
aluminium chloride is formed and volatilizes and may be con-
densed in a cooled receiver.
Sulphur decomposes all of the oxides except alumina and its
analogues. The reaction takes place at a high temperature,
and gives rise to the formation of a sulphide and sulphurous
oxide, or a sulphide and a sulphate if the latter be not decom-
posable by heat.
244
ELEMENTS OF MODERN CHEMISTRY.
If sulphur be heated with cupric oxide, cupric sulphide is
formed and sulphurous oxide is evolved.
2CuO+ 3S = 2CuS +
Cupric oxide.
+ SO²
Cupric sulphide.
However, if calcium oxide (lime) or lead oxide, PbO, be
heated with sulphur, a sulphate and a sulphide are formed.
4CaO + 2S²
Calcium oxide.
3CaS+ CaSO*
Calcium sulphide. Calcium sulphate.
Action of Water upon the Oxides-Metallic Hydrates
and Acids. If some fragments of barium oxide (baryta) be
sprinkled with cold water, an energetic reaction immediately
takes place. The water unites with the metallic oxide with so
much energy that the heat disengaged is sufficient to convert
a portion of the water into vapor. The barium oxide is con-
verted into hydrate.
BaO + HO
Barium oxide.
Ba(OH)2
Barium hydrate.
In the same manner, the oxides of potassium and sodium
energetically absorb the elements of water, being converted
into hydrates.
K²O + H2O
Potassium oxide.
2KOH
Potassium hydrate.
The hydrates of potassium and sodium are soluble in water
and their solutions are caustic, changing tincture of violet to
a green color and restoring the blue color to reddened litmus
solution. These hydrates constitute the alkalies.
The hydrates of barium, strontium, and calcium are likewise
soluble in water to a certain extent, and their solutions are also
somewhat caustic.
Other hydrates are insoluble; they may be obtained by double
decomposition by precipitating the corresponding salts with an
alkali.
If a solution of potassium hydrate be poured into a solution
of cupric sulphate, a light-blue precipitate of cupric hydrate is
formed.
CuSO4 +
Cupric sulphate.
2КОН
K2SO¹ +
Cu(OH)2
Cupric hydrate.
Potassium hydrate. Potassium sulphate.
But if this precipitate be heated, even in the liquid in
which it was formed, it changes brown, and is converted into
oxide by losing its water.
Cu(OH)2 H2O = CuO
—
SULPHIDES.
245
A great number of metallic hydrates undergo the same
decomposition when they are heated.
There are true metallic acids which contain the elements of
an oxide plus the elements of water.
Such are
H2CrO¹
Cro³ + H2O
Chromic acid. Chromium trioxide.
H2MnO¹
MnO3 + H2O
Mangauic acid. Manganese trioxide.
As far as their constitution is concerned, these metallic acids
may be compared to sulphuric acid.
3
H2SO¹ SO³ + H2O
They also resemble sulphuric acid in their chemical func-
tions; each contains two atoms of basic hydrogen, that is, two
atoms of hydrogen which are replaceable by a metal.
SULPHIDES.
Sulphur has a great tendency to unite with the metals, and
the union often takes place with a vivid evolution of heat.
Copper-turnings and iron-filings burn in the vapor of sulphur.
The phenomena which favor or determine, and those which
accompany this combination, have already been indicated, and
we have seen that the presence of a small quantity of water
favors chemical union in a mixture of sulphur and iron-filings.
Certain metals, such as aluminium, zinc, and gold, resist the
action of sulphur even at high temperatures.
In composition the sulphides are analogous to the oxides.
The more important of the transformations which they may
undergo are the following:
Oxygen decomposes all of the sulphides at a temperature
more or less elevated.
Finely-divided potassium sulphide, obtained by calcining the
sulphate with an excess of charcoal, is a black powder, but it
becomes incandescent on contact with oxygen, and if thrown
into the air it produces a shower of sparks. It is known as
Gay-Lussac's pyrophorus. Its fine state of division favors the
absorption of oxygen, and the latter converts it into sulphate.
K2S+0¹
Potassium sulphide.
K2SO¹
Potassium sulphate.
Dry oxygen acts in the same manner upon all the sulphides
21*
246
ELEMENTS OF MODERN CHEMISTRY.
when the corresponding sulphates are stable at high tempera-
tures. In the contrary case, sulphurous oxide is formed, and
a residue of oxide or even of metal is obtained, if the oxide be
decomposable by heat.
If zinc sulphide be roasted, it is converted into zinc oxide,
and sulphurous oxide is evolved; but if sulphide of mercury
be heated in a current of air, metallic mercury is obtained.
HgS + 0²
Mercuric sulphide.
Hg + SO2
Mercury.
Moist oxygen acts upon the sulphides more readily than the
It unites with them at ordinary temperatures, form-
dry gas.
ing sulphates.
FeS + 0¹
Sulphide of iron.
FeSO
Ferrous sulphate.
Chlorine attacks all of the sulphides. forming metallic chlo-
rides and sulphur chloride, if the dry method be employed, or
with deposition of sulphur if the reaction take place in presence
of water.
Water dissolves the alkaline sulphides as well as those of cal-
cium, barium, and strontium; the sulphides of the other metals
are insoluble in water.
Hydrogen sulphide combines with certain sulphides, convert-
ing them into sulphydrates. The analogy will be noticed be-
tween this reaction and that of water upon the oxides.
K'S + H2S
Potassium sulphide.
K²O + H2O
Potassium oxide.
2KSH
Potassium sulphydrate.
2KOH
Potassium hydrate.
CHLORIDES.
Chlorine, bromine, and iodine form with the metals com-
pounds which possess the appearance and certain properties of
salts. Indeed, common salt, or sodium chloride, has given the
name to the entire class of saline compounds. Hence Berze-
lius named chlorine, bromine, and iodine the halogen bodies,
and called their combinations with the metals the haloid salts.
Thus he admitted the relation between these compounds and
the true salts, while at the same time distinguishing them by a
particular name, for while they resemble the salts in their prop-
erties, they differ from them in composition. This subject will
be more fully considered farther on.
CHLORIDES.
247
Composition.-All of the metals, with the exception of plat-
inum, combine directly with free chlorine, but all do not com-
bine with it in the same atomic proportions, and often the same
metal forms several distinct combinations with this element.
Hence the differences in the composition of the chlorides.
They are formed by the union of an atom of metal with one,
two, three, four, five, or six atoms of chlorine.
KCI CaCl2 SbC13
SnCl4
Tin
MoC16
SbC15
Antimony
Antimony Molybdenum
trichloride. tetrachloride. pentachloride. hexachloride.
Potassium Calcium
chloride. chloride.
NaCl FeCl2
BiC13
Sodium
chloride.
AgCl ZnCl2
Ferrous
chloride.
Bismuth
trichloride.
TiCl¹
Titanium
tetrachloride.
Au Cl³
PtCl
Platinum
Silver
Zinc
chloride. chloride.
Gold
trichloride.
tetrachloride.
To these chlorides must be added those which are formed
by the union of two atoms of metal with two or six atoms of
chlorine.
Cu2Cl2
Cuprous chloride.
Ho²C12
Mercurous chloride.
Al²CI
Aluminium chloride.
Cr2 C16
Chromic chloride.
Fe²C16
Ferric chloride.
Cuprous chloride and mercurous chloride contain for the
same quantity of chlorine twice as much metal as cupric chlo-
ride, CuCl², and mercuric chloride, HgCl².
In the first, two atoms of copper or mercury are combined
together to fix two atoms of chlorine, and these two atoms of
metal remain thus associated in all the cuprous and mercurous
compounds. It is the same in the chloride of aluminium, and
in chromic and ferric chlorides. Each of them contains two
atoms of metal intimately associated, and combined as a whole
with six atoms of chlorine.
The same metal may form several combinations with chlorine.
Thallium combines with one or three atoms of chlorine.
Tin and platinum combine with two or four atoms of chlorine.
Antimony combines with three or five atoms of chlorine.
Physical Properties of the Chlorides.-Most of the chlo-
rides are solid and possess the aspect, color, and physical prop-
crties of the salts of the same metal. Nearly all are crystalline
and soluble in water. Only the chloride of silver, mercurous
248
ELEMENTS OF MODERN CHEMISTRY.
and cuprous chlorides are insoluble; plumbic chloride and thal-
lous chloride are but slightly soluble in water.
Certain metallic chlorides are liquid at ordinary tempera-
tures. Such are the tetrachlorides of tin and titanium. Some,
like the chlorides of zinc and bismuth, are solid, but fusible at
low temperatures. These latter were formerly designated as
metallic butters.
Most of the chlorides are fusible at high temperatures, and
many of them are volatile and can be distilled without altera-
tion. It is thus with the liquid chlorides, with the chlorides
of zinc, bismuth, mercury, etc.
Chemical Properties. As a rule, the chlorides are very
stable. Only the chlorides of certain of the precious metals,
as those of gold and platinum, are entirely decomposed by a
high temperature. Some of the higher chlorides lose chlorine
when calcined, and are converted into lower chlorides. Thus,
cupric chloride is converted into cuprous chloride when heated
out of contact with air.
A great number of the chlorides are reduced when they are
heated in a current of hydrogen. In this case, hydrochloric
acid is disengaged, and the metal remains. Thus, hydrogen
removes the chlorine from the chlorides of silver and iron.
These decompositions are determined by the powerful affinity
of chlorine for hydrogen.
The action of the metals upon the chlorides gives rise to
interesting phenomena which are worthy of study.
If corrosive sublimate, which is mercuric chloride, be mixed
with powdered tin and the mixture be heated in a small glass
retort provided with a receiver, a liquid will soon collect in the
latter which diffuses thick vapors in the air. It is the tetra-
chloride of tin, called by the ancient chemists "fuming liquor
of Libavius." It is formed by the decomposition of the mer-
curic chloride, which gives its chlorine to the tin, metallic
mercury being at the same time set free.
Bismuth decomposes mercuric chloride in the same manner
when the two substances are heated together. These experi-
ments are conducted in the dry way. They may be modified
by operating in the presence of water, in which we have re-
marked that most of the chlorides are soluble; it is thus with
mercuric chloride.
If a plate of copper be plunged into a solution of this body,
it at once becomes covered with a layer of metallic mercury.
CHLORIDES.
249
That metal is displaced from its combination by the copper,
which combines with the chlorine: cupric chloride is formed,
and after the lapse of some time, the liquid will contain only
that compound. It becomes green, and if a plate of zinc be
plunged into it, the copper will be precipitated in its turn, and
the zinc will combine with the chlorine and enter the solution;
the liquid then contains zinc chloride.
Thus, the metals reciprocally displace each other from their
solutions, according to the energy of their affinities. In this
case it is the possession of the chlorine for which they antago-
nize each other, the stronger driving out the weaker. It must
be remarked that in this respect the chlorides behave in the
same manner as the oxygen salts.
This analogy is continued in innumerable reactions. Solu-
tions of the chlorides enter into double decompositions like
solutions of the true salts. If potassium hydrate be added to
a solution of either cupric sulphate or cupric chloride, in each
case a light-blue precipitate of cupric hydrate is obtained.
CuSO + 2KOH
K²SO + Cu(OH)2
Cupric sulphate. Potassium hydrate. Potassium sulphate. Cupric hydrate.
CuCl2 + 2KOH
Cupric chloride.
2KC
Potassium chloride.
Cu(OH)2
But cupric chloride resembles the sulphate in still another
property. When perfectly pure it is yellowish. If it be moist-
ened with water, it becomes heated and assumes a green color.
It has combined with water, and will dissolve if enough of that
liquid be added. A green liquor is thus obtained, which de-
posits, by spontaneous evaporation, magnificent green prisms.
These crystals are hydrated cupric chloride. They contain
water of crystallization, and can only exist on that condition.
It is the same with the crystals of cupric sulphate.
Thus, certain chlorides are capable of taking water of crys-
tallization like the true salts.
We may complete the analogy by one more characteristic.
1. If a solution of aluminium sulphate be added to a con-
centrated solution of potassium sulphate, and the mixture be
agitated, an abundant crystalline deposit is obtained. This is
a double salt,-potassium and aluminium sulphate, or alum.
2. If a solution of platinic chloride be added to a concen-
trated solution of potassium chloride, a yellow precipitate is
L*
250
ELEMENTS OF MODERN CHEMISTRY.
formed at once. It is the double chloride of potassium and
platinum, which contains all of the elements of two molecules
of potassium chloride and one molecule of platinic chloride.
This example shows that the chlorides can combine together,
forming double chlorides, just as the true salts may combine
together to form double salts.
SALTS.
Definition. The salts are formed by the substitution of
metal for the hydrogen of the acids, and they result from the
action of the acids upon the metallic oxides or hydrates. The
name acid applies to two classes of compounds: the first are
formed by the union of hydrogen with a strongly electro-nega-
tive element, such as chlorine or bromine; these are the hy-
dracids. Such are hydrochloric acid, HCl, and hydrobromic
acid, HBr.
The acids of the other class are more complicated, contain-
ing hydrogen united with a strongly electro-negative oxidized
group, that is, a group of atoms formed by oxygen and another
element; these are the oxacids. Such are nitric acid, HNO³,
and sulphuric acid, H2SO¹.
These two classes of acids behave in the same manner in
contact with bases, that is, with metallic oxides or hydrates.
1. If hydrochloric acid be gradually added to a concentrated
solution of potassium hydrate, the liquid becomes heated,
and, as it is neutralized by the acid, a white crystalline de-
posit separates and augments on cooling: it is potassium
chloride.
2. If sulphuric acid diluted with its volume of water be
cautiously and gradually added to a concentrated solution of
potassium hydrate, the liquid becomes heated, and, as it is
neutralized by the acid, a white crystalline deposit separates
and increases on cooling: it is potassium sulphate.
The analogy between the two reactions is marked. In each
casc a powerful base, potassium hydrate, has been neutralized
by an energetic acid; the reaction has been accompanied by
the production of heat, and has given rise to the formation
of a saline matter which has been deposited. The part of the
reaction which is invisible is the formation of water. This
formation of water, which always accompanies the generation
SALTS.
251
of a salt in the ordinary manners, is expressed in the following
equations:
KOH + HC
Potassium hydrate.
2KOH + H2SO¹
KCI
+ H2O
Potassium chloride.
K2SO
Potassium sulphate.
+ 2H2O
These reactions, it will be seen, consist in an interchange of
elements, a double decomposition. The hydrogen of the acid
is exchanged for the metal of the potassium hydrate and by
the exchange the potassium hydrate is converted into water,
while the acid, that is, the salt of hydrogen, is converted into a
salt of potassium. All hydrogen compounds capable of thus
exchanging their hydrogen for an equivalent quantity of metal,
fill the functions of acids, and these acids become salts when
their hydrogen is thus replaced by a metal. It may then be
seen what an important part hydrogen plays in the formation
of salts. From whence comes this property, this capacity for
such exchanges, and of replacement by metals? Without
doubt from the element or group with which the hydrogen is
united in the acids; and in this respect chlorine and sulphur
play the same parts in hydrochloric and sulphydric acids that
the oxidized groups play in nitric, sulphuric, and phosphoric
acids.
HCI
Hydrochloric acid.
H(NO3)
Nitric acid.
H(CIO)
Chloric acid.
H2S
Sulphydric acid.
H2(SO)
Sulphurous acid.
H²(SO¹)
Sulphuric acid.
H³ PO³)
Phosphorous acid.
H³(PO¹)
Phosphoric acid.
This property is characterized by saying that the elements or
groups, to which the hydrogen is united, are strongly electro-
negative, or acid, in opposition to the hydrogen, which is
strongly electro-positive, or basic.
When such an acid reacts upon an oxide, or upon a hydrate,
an interchange of elements takes place, and a salt and water
are formed; the latter is a constant product necessary to the
reaction. Other examples may be added to those already given.
If a current of hydrogen sulphide be passed into a solution
of potassium hydrate until no more is absorbed, potassium
sulphydrate and water are formed.
H2S + KOH
KSH + H2O
Potassium sulphydrate.
252
ELEMENTS OF MODERN CHEMISTRY.
If an excess of dilute sulphuric acid be poured into a solu-
tion of potassium hydrate, potassium acid sulphate and water
are formed.
H2SO4 + KOH
KHSO¹ + H2O
Potassium acid sulphate.
Lastly, if cupric oxide be heated with dilute sulphuric acid,
it dissolves, coloring the liquid blue. Cupric sulphate and
water are formed.
H2SO⭑
H2SO4 +
+ CuO
CuSO4 + H2O
Cupric oxide. Cupric sulphate.
Neutral, Acid, and Basic Salts. If the salts result from
the substitution of the metals for the basic hydrogen of acids,
it is evident that their composition must be related to that of
the acids from which they are derived. We know that the
latter contain one, two, or three atoms of hydrogen, capable of
being replaced by an equivalent quantity of metal: they are
monobasic, dibasic, and tribasic. It is evident that the salts
must present analogous differences in their composition, accord-
ing as they are derived from a monobasic, a dibasic, or a tribasic
acid.
A salt is neutral when the basic hydrogen has been entirely
replaced by an equivalent quantity of metal. But the substi
tution may be only partial, for when an acid contains two atoms
of basic hydrogen, only one of these atoms may be replaced by
one atom of metal; there will then remain in the salt thus
formed one atom of basic hydrogen.
When an acid contains three atoms of basic hydrogen, it
may happen that only one is replaced by one atom of metal;
there will then remain in the salt two atoms of basic hydrogen;
or it may be that two atoms of hydrogen are replaced by an
equivalent quantity of metal, and there will then remain in the
salt a single atom of basic hydrogen.
Whenever basic hydrogen thus remains in a salt, the satura-
tion of the acid is said to be incomplete. The salt formed
ordinarily retains the characters of an acid; it is an acid salt.
The following table indicates the possible cases of complete
or incomplete saturation which may be presented by a mono-
basic, a dibasic, and a tribasic acid:
HNO3
Nitric acid.
H2SO¹
Sulphuric acid.
H3PO4
Phosphoric acid.
SALTS.
253
KNO³
K
H} SO
Potassium nitrate.
Potassium acid sulphate.
K2SO4
Potassium sulphate.
K)
H & PO
Monopotassium phosphate.
K2
HPO
Dipotassium phosphate.
K³PO¹
Tripotassium phosphate.
Certain neutral salts possess the property of combining with
the hydrates or the oxides. The compounds so formed contain
all of the elements of the neutral salt, plus those of the hydrate
or oxide; they are called basic salts. Thus, the oxides of
lead and copper may combine with the various salts of lead and
copper, forming basic salts of those metals.
Richter's Laws.-Towards the close of the last century
fruitful investigation was made into the phenomena of neu-
tralization or saturation of acids by bases. We know that a
given weight of acid requires for its neutralization a fixed and
absolutely invariable quantity of a given base. Thus, for the
conversion of 1000 grammes of sulphuric acid into neutral
potassium salt, a quantity of potassium hydrate corresponding
to 961 grammes of potassium oxide, K'O, is required. To
saturate these 1000 grammes of sulphuric acid, it is necessary
to take weights of the oxides which are invariable for each one
separately, but which vary among themselves.
Thus, 1000 grammes of concentrated sulphuric acid are neu-
tralized by the following quantities of the oxides named :
Potassium oxide
Sodium oxide
961 grammes.
Barium oxide
Calcium oxide
Zinc oxide
Cupric oxide
•
Mercuric oxide.
Silver oxide
•
632
1561
"C
571
66
866
(6
811
(
2204
"
2367
Again, to neutralize 1000 grammes of the most concentrated
nitric acid, the following quantities of the same oxides are
required:
Potassium oxide
747 grammes.
492
Sodium oxide
Barium oxide
•
Calcium oxide
Zinc oxide
Cupric oxide
Mercuric oxide
Silver oxide
•
•
•
•
1214
(C
444
651
(C
631
(C
•
1714
1841
(C
22
254
ELEMENTS OF MODERN CHEMISTRY.
Richter was the first to remark that these latter quantities
are precisely in the same ratio to each other as the quantities
of oxides which neutralize 1000 grammes of sulphuric acid.
Thus,
961
747
632
492
961
717
1561
1214
961
747
etc.
571
444
In other words, the quantities of oxides which neutralize a
given weight of one acid are proportional to the quantities of
the same oxides which neutralize the same weight of another
acid. This law of the composition of salts was discovered,
towards the close of the last century, by Richter, a chemist of
Berlin. Berzelius quoted another German chemist, Wenzel,
as the author of this law of proportion, and his error has
appeared in all of the treatises on chemistry during the last
fifty years.
Richter also studied the phenomenon of the precipitation of
metallic solutions by the metals. It is known that when a
piece of iron is plunged into a solution of cupric sulphate, the
iron dissolves, displacing a certain quantity of copper, without
other change. Since the new salt formed, ferrous sulphate, ex-
ists in the solution in the same conditions of neutrality as the
cupric sulphate, the quantities of metal which thus displace
each other are equivalent. As neither oxygen nor acid is set
at liberty, it must be admitted that the respective quantities of
the metals, in the salts successively formed, are united to the
same quantity of oxygen. It has even been supposed that in
the salts which, like the sulphates, contain four atoms of oxygen,
the metal is in intimate relation with one of these atoms, which
is precisely sufficient to constitute the metal in the state of
monoxide.
CuSO*
FeSO¹
CuO,SO³
FeO,SO³
If this were so, it is evident that when cupric sulphate is
decomposed by iron, the quantity of metal which enters into
solution would combine or enter into relations with precisely the
quantity of oxygen abandoned by the copper. This quantity of
oxygen being constant, the quantities of the metals which com-
SALTS.
255
bine successively with it, differ, but are equivalent to each
other, and it is evident that the oxides thus formed would be
more rich in oxygen as the weight of metal which enters into
solution is less considerable; in other words, the richness of all
these oxides in oxygen is inversely proportional to the weights.
of the metals which successively become dissolved; it was in
this form that Richter announced the second law of the com-
position of salts. It will be seen that this law is implied in
the first, and that both are but particular cases and natural con-
sequences of the theory of equivalents, as it is understood at
present and as it has already been explained (page 23).
General Properties of Salts.-The salts present very differ-
ent colors. Those which are formed by an acid possessing a
color are themselves colored; such are the chromates, manga-
nates, and permanganates.
Most of the colored oxides form salts presenting various
colors.
Ferrous salts are bluish-green.
Ferric salts are yellow or yellowish-brown.
Manganese salts are rose-colored.
Chromium salts are dark green.
Nickel salts are green.
Cobalt salts are currant-red or blue.
Cupric salts are blue or green.
Gold salts are yellow.
It is to be remarked that these various colors are only devel-
oped, as a rule, when the salts are hydrated, that is, combined
with water of crystallization. The taste of the salts depends
upon their solubility; it is wanting altogether or but slightly
marked in the insoluble salts; more or less pronounced and
very diverse in the soluble salts. The salts of magnesium are
bitter; the aluminium salts are astringent; those of iron astrin-
gent, with a metallic after-taste; the salts of lead are at the
same time sweet and astringent; the salts of copper, antimony,
and mercury have an acrid metallic taste, which is nauseous,
and is called styptic.
The salts generally present regular forms, more frequently
occurring in crystals. Some of them are obtained as amor-
phous precipitates, but in nature even these may assume the
crystalline state.
Isomorphism.-Certain salts which possess similar atomic
compositions crystallize in identical or nearly identical forms;
they are called isomorphous. It is thus with the double sul-
256
ELEMENTS OF MODERN CHEMISTRY.
phates, which are called alums, and of which ordinary alum
or aluminium and potassium sulphate is the type. These alums
are formed by the union of a sulphate, R2(SO4)3, with a sul-
phate, M²SO, and they all contain 24 molecules of water of
crystallization.
Thus, ordinary alum,
Al²(SO¹)³.K²SO* + 24H2O
Aluminium and potassium double sulphate.
is isomorphous with chrome alum and iron alum.
Cr²(SO¹)³.K²SO¹ + 24H²O
Chromium and potassium double sulphate.
Fe²(SO¹)³.K*SO* + 24H²O
Iron and potassium double sulphate.
All of these alums crystallize in regular octahedra. Further,
a solution containing two alums, for example, aluminium and
potassium sulphate and aluminium and ammonium sulphate,
deposits on concentration crystals in which the two salts are
mixed. Such is the character of isomorphous bodies; crystal-
lizing in the same form, they may mix together and replace
each other in all proportions in the same crystal. Many exam-
ples of isomorphism will be cited in the course of this work.
It will now be sufficient to add that this idea of isomorphism
has rendered valuable service to chemical theory by permitting
the grouping together of bodies similar both in crystalline form
and atomic constitution, and by furnishing in such cases useful
indications for the determination of the atomic weights. It is
evident that when two similar combinations, two sulphates, for
example, are recognized to be isomorphous, it is necessary to
represent their constitutions by analogous formulæ, and the
latter can only be possible under the condition that the atomic
weights of the metals contained in these sulphates have known
values.
Action of Water upon the Salts.--If water be poured upon
and agitated with powdered chalk, a white, cloudy liquid is
obtained. The chalk is suspended in the water without being
dissolved; it is simply held up in the form of minute particles,
and if the liquid be allowed to stand, the precipitate is de-
posited, and clear water again appears above the deposit.
However, if saltpetre, or potassium nitrate, be agitated with
water, a colorless, transparent liquid is obtained. The saltpetre
is dissolved in the water; it has disappeared as a solid body.
SALTS.
257
It is melted by the water, as is commonly said, and is uniformly
diffused through the liquid. It has itself become liquid, and
this is the phenomenon of solution. It is accompanied by a
production of cold, that is, an absorption of heat; for in assum-
ing the liquid state and becoming diffused throughout the water,
the saltpetre must absorb heat.
If the introduction of powdered nitre into the solution be
continued, the solid still disappears, but a time arrives when
the salt introduced ceases to dissolve; for water at a given tem-
perature can only dissolve a fixed quantity of a salt, and when
this limit is attained, the solvent force of the water upon the salt-
petre is exhausted. The water is then said to be saturated with
the salt, and any excess of the latter remains in the solid state.
But if now the solution be heated, this excess is in its turn
dissolved, for the solubility augments with the temperature,
and as the latter is elevated, a larger quantity of the salt is dis-
solved. When the liquid begins to boil, the temperature and
the solubility of the salt have reached their extreme limit.
If the boiling saturated solution be allowed to cool, it depos-
its a large portion of the salt in the form of crystals. In this
manner voluminous, colorless, and transparent prisms are ob-
tained which fill the vessel, and which are surrounded by a
solution of saltpetre, saturated at the temperature to which the
liquid has been cooled. This liquid is called the mother-liquor
of the crystals. It is thus that soluble salts are crystallized by
cooling their hot saturated solutions.
Generally the same facts are observed for other soluble salts.
Their solubility increases with the temperature; there are,
however, some exceptions to this rule. Sodium chloride is
not more soluble in hot than in cold water, and gypsum, or
calcium sulphate, is sensibly more soluble in cold than in hot
water; for, while 500 parts of boiling water are requisite to
dissolve one part of gypsum, only 460 parts of cold water are
necessary to dissolve the same quantity. The maximum solu-
bility of sodium sulphate is between 32 and 33°.
Crystals of nitre may be obtained by another process. We
may expose the cold saturated solution to the air at the ordi-
nary temperature, or, better still, place it in a bell-jar over a
vessel containing sulphuric acid. The water of the solution
slowly disappears, and, as it is dissipated in vapor, a portion of
the dissolved salt separates in the solid form. The crystals thus
formed by spontaneous evaporation are generally very regular.
22*
258
ELEMENTS OF MODERN CHEMISTRY.
But water exerts another and a different action upon the
salts.
Perfectly dry cupric sulphate, CuSO4, is a white powder.
If water be poured upon it, it becomes blue and dissolves, com-
municating to the liquid a blue color and notably raising its
temperature. On evaporation, this liquid deposits crystals of
blue vitriol, and if these be compared with the dry white pow-
der with which we started, they will be found to differ from it
by the water they contain. We have employed the anhydrous
salt, and have hydrated it. In fact, the sulphate, CuSO¹, has
absorbed five molecules of water, with which it has combined,
and this combination, like all others, has taken place with the
production of heat. The water which is thus absorbed by cer-
tain salts, and which combines with them in definite propor-
tions, is necessary to the formation of their crystals; it is called
water of crystallization.
It is not necessary to the constitution of the salts them-
selves; they can exist without it, and generally lose it when
they are heated to a temperature more or less elevated, without
undergoing any other decomposition. Certain salts abandon
their water of crystallization with such facility that they give
it up to the surrounding air when the latter is not saturated
with moisture. They then become opaque and lose their
forms, for crystals cease to exist when their water of crystalli-
zation is disengaged. These salts become covered with a dry
powder in the air and are called efflorescent salts.
It is seen by the example just cited that the phenomenon
of solution of salts in water, which depends upon a physical
action, upon a change of state, is often complicated with a true
combination of the salt with water, that is, a chemical action
which disengages heat. The latter is generally more energetic
than the physical action, and the difference between the two
effects is then manifested by an elevation of temperature.
But the physical phenomenon is produced alone when the
salt which dissolves is incapable of combining with water of
crystallization. A depression of temperature is then observed,
as we have seen in the case of nitre, the crystals of which are
anhydrous; but another example will more clearly illustrate
this important phenomenon.
If water be poured upon recently fused and powdered calcium
chloride, the salt dissolves with production of heat. It changes
not only its state but its composition; it combines energetically
SALTS.
259
with the water, and this combination produces more heat than
is absorbed by the change of state. Hence there is an eleva-
tion of temperature.
If calcium chloride, combined with its water of crystalliza-
tion, be rapidly mixed with snow, the salt is so soluble in water
that it causes the snow to melt at the same time that it becomes
liquid itself. Here there is no combination, no chemical action,
and no heat is disengaged. It is a double physical phenome-
non,-fusion of the snow and fusion of the calcium chloride,
and neither of these bodies can undergo a change of state with-
out absorbing heat. Hence there is a depression of tempera-
ture which may reach —40°.
ture.
A mixture of snow and calcium chloride is a freezing mix-
A mixture of equal parts of common salt and broken
ice or snow is frequently used for the production of cold.
The phenomenon of the solution of salts in water presents
none of the characteristics of a chemical action; it does not
take place in definite proportions.
In fact, a soluble salt requires for its complete solution a
quantity of water, which is always the same for a certain weight
of the salt at a given temperature; but there exists no atomic
relation between this quantity of water and the weight of the
salt which is dissolved.
Further, although the solubility of a salt presents for each
temperature a maximum limit, that is, although a given weight
of a salt requires for its solution a quantity of water which
invariable and which cannot be diminished, when the solution
has been accomplished an indefinite quantity of water may be
added, and the liquid will still remain perfectly homogeneous.
Supersaturation.-We have seen that a saturated solution.
of a salt at a given temperature generally deposits a part of
that salt on cooling. This is not always the case; it sometimes
happens, if the cooling take place under certain conditions, that
a portion of the salt, which the difference in temperature should
reduce to the solid state, still remains in solution. The solu-
tion is then said to be supersaturated. Sodium sulphate and
alum have a great tendency to form such solutions.
A hot, saturated solution of sodium sulphate is contained in
the tube A (Fig. 95). It is heated to boiling, so that the vapor
escapes by the drawn-out extremity. By the aid of a blow-
pipe, the tube is then sealed at C, before the vapor can con-
dense, and is then allowed to cool. A vacuum is formed above
260
ELEMENTS OF MODERN CHEMISTRY.
the solution, for the air has been driven out by the vapor. The
cold liquid remains limpid; it deposits no crystals. But the
instant the drawn-out point of the tube is broken off, the air
enters and crystallization at once commences at the surface and

A
FIG. 95.
proceeds throughout the entire mass, which becomes solid; at
the same time an elevation of temperature may be observed.
100 grammes of water and 200 grammes of crystallized so-
dium sulphate may be heated to ebullition in a narrow-necked
flask, and as soon as vapor begins to issue from the mouth, the
latter may be covered with a watch-glass and the whole allowed
to cool tranquilly. The salt remains dissolved, and the solution.
contained in the flask is supersaturated; but as soon as the
watch-glass is removed the liquid becomes à solid mass of crys-
tals (Loewel).
In the first experiment it is the sudden entry of the air
which determines the crystallization; in the second, it is the
free access of air, and it may be admitted that in each case the
air acts by the corpuscles which it holds in suspension, and
which, falling into the solution, determine the crystallization.
Indeed, Loewel has shown that air which has been filtered
SALTS.
261
through cotton-wool has lost the property of causing supersat-
urated solutions to crystallize.
But what is the nature of these particles which by falling
upon the surface of supersaturated solutions occasion crystalli-
zation? The researches of Gernez have thrown great light upon
this question. According to him, they are saline particles simi-
lar to the salt dissolved. The sodium sulphate is deposited in
the preceding experiments because the entry of the air has
allowed an imperceptible particle of sodium sulphate to fall
upon the surface of the liquid, and around this particle the
crystallization begins immediately and is propagated through-
out the entire mass of the supersaturated liquid. The air then
contains a trace of sodium sulphate, as it contains a trace of
common salt and of carbonate and sulphate of calcium. These
particles are suspended in the air in a state of extreme division,
and are carried from great distances by the winds.
A boiling saturated solution of sodium hyposulphite may be.
allowed to cool in a carefully-corked flask. When cold, it is so
concentrated that it possesses an oily consistency. The flask
may be carefully uncorked and the surface of the liquid touched
with a rod to the end of which a small particle of sodium hy-
posulphite has been made to adhere. Crystallization at once
commences at the spot where the rod touches the liquid, and
in a few seconds the whole mass becomes solid. There is at
the same time a notable disengagement of heat (Gernez).
The crystallization will also take place if a particle of sodium
sulphate be allowed to fall into the solution, for the latter salt
possesses the same crystalline form as sodium hyposulphite, and
an analogous constitution.
Ebullition of Saline Solutions.-Aqueous solutions of the
salts generally possess a boiling-point higher than that of water.
Thus, a saturated solution of common salt boils at 108.4°; a
saturated solution of potassium nitrate boils at 115.9°; and a
saturated solution of calcium chloride boils only at 179.5°.
Action of Heat upon the Salts.-The hydrated salts lose
their water when they are heated. Ordinarily, a temperature
of 100° is sufficient to expel the water of crystallization. Cer-
tain salts melt in this water before losing it; they are so soluble
in hot water that they dissolve in the water which at a lower tem-
perature constitutes them in the crystalline state. This is called
aqueous fusion. A great number of anhydrous salts melt when
they are exposed to intense heat; this is called igneous fusion.
262
ELEMENTS OF MODERN CHEMISTRY.
Heat exerts a decomposing action upon many salts. Upon
this point it is difficult to give general laws. It can only be
said that the stability of a salt depends upon three conditions,
namely, the fixedness of the corresponding acid, the stability
of the corresponding oxide, and the energy of the affinity with
which the two react together to form the salt.
Thus the salts of acids decomposable by heat are themselves
decomposed at an elevated temperature. It is thus with the
chlorates, the perchlorates, and the nitrates. Among the sul-
phates, some are decomposable, others are fixed. The latter are
those of potassium, sodium, barium, strontium, calcium, mag-
nesium, lead, etc. The corresponding oxides of potassium,
sodium, barium, etc., are fixed bases, and possess a powerful
affinity for sulphuric acid. Hence their sulphates are stable.
Most of the carbonates are decomposable by heat; indeed,
the affinity of carbonic acid for the bases is as a rule feeble.
It is exceptionally strong for the alkaline bases; hence the alka-
line carbonates and barium carbonate resist the action of heat.
Action of Electricity upon the Salts. When an electric
Kadamay Jaza 1 sti
FIG. 96.
+
current traverses the aque-
ous solution of a salt, the
latter is decomposed. The
metal separates at the neg-
ative pole, and the other
element of the salt at the
positive pole. This other
element may be an elec-
tro-negative element, such
as chlorine, or an oxidized
group, that is, a group of
atoms, one or more of
which is oxygen.
The electrolysis of a
salt may be effected as
follows: An U tube (Fig.
96) contains a solution of
cupric chloride. In cach
branch a plate of platinum
dips into the liquid, and
these plates, connected by
of a battery, constitute
As soon as the current

conducting wires with the two poles
the positive and negative electrodes.
SALTS.
263
passes, the electro-positive element of the salt, the copper, is
deposited upon the electro-negative electrode, and the chlorine,
which is electro-negative, is disengaged at the positive electrode.
A part of this chlorine combines with the platinum electrode
by a secondary reaction, forming platinum chloride, but the
principal action, that is, the decomposition of cupric chloride
by electrolysis, is represented by the following equation:
Cu Cl2
Cupric chloride.
+
Cu + C12
Copper. Chlorine.
If the cupric chloride be replaced by cupric sulphate, the
current will decompose this salt into copper, which deposits
upon the negative electrode, and into SO, which possesses no
stability, and consequently breaks up at the positive electrode.
into SO³, which combines with the water to form sulphuric
acid, and O, which is disengaged at the positive electrode.
>
The decomposition of the SO is a secondary action. The
principal action accomplished by the work of the current is
expressed by the following equation:
CuSO
Cupric sulphate.
+
Cu + SO
Copper.
Oxidized group.
The secondary reactions are as follows:
SO4 SO³ +0
SO³ + H2O H2SO4
The experiment may be repeated upon potassium sulphate,
and a solution of this salt colored by the syrup of violets is in-
troduced in the U tube. As soon as the current passes, bub-
bles of gas are seen to arise from each electrode. Free oxygen
appears at the positive electrode, as in the preceding case, and
at the same time the liquid filling this branch of the tube as-
sumes a red color. This is the evidence of the presence of
sulphuric acid formed at the positive electrode.
The gas disengaged at the negative electrode is hydrogen,
which is produced by a secondary action of the water upon the
potassium which is removed from the salt at the negative pole.
Potassium hydrate is thus formed, and the syrup of violets
in this branch of the tube is colored green. The principal ac-
tion accomplished by the current is expressed, as in the pre-
ceding cases, by the equation
K +
K2SO
Potassium sulphate. Potassium.
SO+
Oxidized group.
264
ELEMENTS OF MODERN CHEMISTRY.
The metal, which is electro-positive, is carried to the nega-
tive pole; the oxidized group to the positive pole. But the
two elements thus separated have provoked or undergone sec-
ondary actions independent of the work of the current. The
potassium has decomposed the water, the oxidized group has
been broken up, as explained in the preceding case.
It will be understood from these reactions that all of the
salts, whatever may be their nature, undergo the same kind of
decomposition when submitted to the action of an electric cur-
rent. They are separated into two elements. The one is elec-
tro-positive, and is liberated at the negative pole; this is always
the metal. The other is electro-negative and goes to the posi-
tive pole, whether it be a simple body, such as chlorine, or an
oxidized group, such as SO. It will also be seen that such
groups occupy in the oxidized salts the same position held by
chlorine in the chlorides. Such is the principal action, that is,
the decomposition, accomplished by the action of the electric
current, a decomposition which is called electrolysis.
Action of the Metals upon the Salts.-The metals may
displace each other in their saline solutions.
If a plate of copper be plunged into a solution of silver
nitrate, the copper enters into solution in the form of cupric
nitrate, displacing and precipitating the silver.
Cu + 2AgNO3
Silver nitrate.
Cu(NO3)2 + Ag²
Cupric nitrate.
If a piece of iron be introduced into a solution of cupric
sulphate, the iron instantly becomes covered with a layer of
metallic copper, precipitated by a portion of the iron which
enters the solution.
Fe + CuSO4
Cupric sulphate.
Cu + FeSO¹
Ferrous sulphate.
If a strip of zinc around which some brass wires have been
twisted be suspended in a dilute solution of plumbic acetate,
the zinc will slowly displace the lead, which will be deposited
in brilliant scales upon the brass wires. The latter gradually
assume the appearance of fern-leaves, and the experiment
constitutes the formation of the lead-tree.
Richter, of Berlin, was the first to remark (1792) that the
metals displace each other in their saline solutions without the
neutrality of the latter being disturbed. When a neutral salt
is precipitated by a metal, a new neutral salt results. The
BERTHOLLET'S LAWS.
265
ferrous sulphate formed by the action of iron upon cupric sul-
phate is neutral like the latter.
It may be further stated that in this respect the chlorides
behave like the oxygen salts. Iron displaces copper from cu-
pric chloride as from the sulphate. In the first case it com-
bines with Cl², in the second with SO¹, and in this circumstance
again the latter group acts in the same manner as chlorine.
CuCl2 +
Fe
Cupric chlorido.
+
FeCl2 + Cu
Cu(SO) Fe
Cupric sulphate.
Ferrous chloride.
Fe(SO¹)
+ Cu
Ferrous sulphate.
The following table indicates the order in which the metals
precipitate saline solutions:
SALTS OF WHICH THE METALS ARE PRECIPITATED BY
CERTAIN METALS.
•
Salts of tin
Salts of antimony
Salts of bismuth
Salts of lead
Salts of copper
Salts of mercury
•
Salts of silver
•
Salts of platinum
Salts of gold.
❤
•
reduced by iron, zinc,
and all the preceding
metals
reduced by iron, zinc,
manganese,
cobalt,
and all the preceding
metals
reduced by iron and zinc.
BERTHOLLET'S LAWS.
To conclude this general study of the salts, it only remains
to indicate the actions exerted upon them by the acids and the
bases, and the reciprocal actions of the salts themselves. These
facts have been established and discussed principally by Ber-
thollet, who demonstrated the influence of physical conditions,
such as insolubility and volatility, upon the direction of chem-
ical decompositions.
Action of Acids upon the Salts.—When an acid, that is, a
salt of hydrogen, is added to a metallic salt, the former tends.
to exchange elements with the latter, in such a manner as to
form a new salt and a new acid.
If sulphuric acid be added to powdered potassium nitrate,
M
23
266
ELEMENTS OF MODERN CHEMISTRY.
the latter partially dissolves without the aid of heat, and
potassium acid sulphate and nitric acid are formed.
KNO³ + H2SO¹
Potassium nitrate. Sulphuric acid.
HNO3 + KHSO¹
Nitric acid. Potassium acid sulphate.
But this reaction is by no means complete. Powerful as
are its affinities, the sulphuric acid cannot decompose the whole
of the potassium nitrate unaided by heat; a portion of the latter
salt remains unaltered in presence of the excess of sulphuric
acid, so that the resulting thick and fuming liquid really con-
tains two acids and two salts, namely:
Sulphuric acid.
Nitric acid.
Potassium acid sulphate.
Potassium nitrate.
The reaction takes place as if two acids were in presence of
a single base. There is a conflict between the acids, and they
tend to divide the base, which is potassium, in such a manner
that each acid may saturate a portion.
Hence the decomposition of potassium nitrate is not com-
plete, and it is arrested as soon as the nitric acid set free can
dispute with the sulphuric acid the possession of the base.
There is then established a state of equilibrium between the
two acids, both remaining in presence of the two salts.
But this equilibrium is unstable and may be deranged by
various circumstances.
If the acid mixture be heated, abundant white vapors are
disengaged. It is the nitric acid which volatilizes. But the
sulphuric acid becomes thus preponderant in the liquid and
decomposes another portion of potassium nitrate, and, if the
volatilization of the nitric acid set free be not arrested by the
removal of the heat, it is evident that nothing can prevent the
complete decomposition of the potassium nitrate by the sul-
phuric acid. The nitric acid, which by its presence alone
prevented this total decomposition, is rendered powerless.
Such is the influence of volatility or the gaseous state upon
the progress of decompositions; it is manifested in the highest
degree in acids more volatile than nitric acid, such as carbonic
and sulphurous acids. We have already seen that the carbon-
ates and sulphites are easily and entirely decomposed by the
energetic acids.
While the volatility of acids favors the decomposition of
their salts, insolubility may play an analogous part.
BERTHOLLET'S LAWS.
267
If hydrochloric acid be added to a solution of potassium sili-
cate, a gelatinous precipitate of silicic acid is at once produced,
and at the same time potassium chloride is formed. The de-
composition is complete, for the silicic acid is insoluble.
If sulphuric acid be poured into a solution of barium nitrate,
a precipitate of barium sulphate is immediately formed, while
at the same time nitric acid is set free.
Ba(NO3)2
Barium nitrate.
+ H2SO4
Sulphuric acid.
2HNO3 + BaSO4
Nitric acid. Barium sulphate.
In this case also the decomposition is complete, for the ba-
rium sulphate is insoluble.
In these two reactions, the division of the base between the
two acids cannot take place, since one of the products is imme-
diately removed from the sphere of action by its insolubility.
In the first case, it is the newly-formed acid which is precipi-
tated; in the second, it is the newly-formed salt which is de-
posited in the insoluble state.
Influence of Mass.-One other circumstance can influence
the extent of these decompositions: it is the relative masses of
the bodies which are in presence of each other.
In the first experiment, it was supposed that an amount of
sulphuric acid had been added to potassium nitrate sufficient to
produce the double decomposition. If a large excess had been
employed, it is evident that it would have become preponderant
in the mixture, and that it would have displaced a more con-
siderable portion of nitric acid.
The influence of mass is manifested in the case of very feeble.
acids, and permits them to displace stronger acids. If a small
quantity of tricalcic phosphate be introduced into water charged
with carbonic acid, the latter, compensating by its mass for its
deficiency in energy, will remove from the phosphate a portion
of its base. Calcium dicarbonate and calcium acid phosphate
are formed, both of which are soluble.
Such, according to Berthollet, is the influence of insolubility
and volatility upon the phenomena of double decomposition;
such, on the other hand, is the influence of mass.
The same
conditions intervene, and in the same manner, in the reactions
which we are about to study.
Action of Bases upon the Salts. We will here consider
only the action of the soluble bases, that is, the alkaline hy-
drates.
268
ELEMENTS OF MODERN CHEMISTRY.
If a solution of potassium hydrate be poured into a solu-
tion of sodium sulphate, no apparent change takes place; but,
according to the principle which has just been announced, it is
probable that the potassium hydrate has liberated a portion
of sodium hydrate.
+ 2KOH
K2SO4 +
Na2SO¹
2NaOH
Sodium sulphate. Potassium hydrate. Potassium sulphate. Sodium hydrate.
But this decomposition cannot be complete, and the liquid
must contain four bodies, namely:
Sodium sulphate.
Potassium sulphate.
Sodium hydrate.
Potassium hydrate.
If potassium hydrate be added to a solution of cupric sul-
phate, a light-blue precipitate of cupric hydrate is obtained.
In this case the decomposition is complete, owing to the insol-
ubility of the cupric hydrate which cannot dispute with the
potassium hydrate the possession of the acid.
K2SO¹ +
CuSO + 2KOH
Cu(OH)2
Cupric sulphate. Potassium hydrate. Potassium sulphate. Cupric hydrate.
If a solution of barium hydrate be poured into a solution of
potassium sulphate, a precipitate of barium sulphate is pro-
duced, and potassium hydrate remains in solution. In this
case again, the decomposition is complete, by reason of the in-
solubility of the barium sulphate. The potassium cannot di-
vide the acid with the barium, for the latter escapes with all
of it in the form of insoluble sulphate.
K2SO¹ + Ba(OH)2
BaSO4 + 2KOH
Potassium sulphate. Barium hydrate. Barium sulphate. Potassium hydrate.
Action of the Salts upon each other. The action of salts
upon each other is what would naturally follow from the prin-
ciples exposed in treating of the action of acids upon salts.
Indeed, the latter possess the same constitution as the acids,
and in their reactions upon salts should give rise to phenomena
of the same order. These are exchanges of elements, double
decompositions, which take place and are more or less complete,
according to the physical conditions of the bodies which are
produced, and also according to the relative masses of the re-
acting bodies.
In the first place, we must consider the reciprocal actions of
the soluble salts.
BERTHOLLET'S LAWS.
269
If a solution of cupric sulphate be treated with a solution
of sodium chloride, no precipitate is formed, but the blue color
of the liquid is changed to green. This color is that of cupric
chloride, and it may be supposed that the latter salt is formed
by the reciprocal action of the sodium chloride and cupric
sulphate.
+ 2NaCl
CuSO
Na2SO + Cu Cl2
Cupric sulphate. Sodium chloride. Sodium sulphate. Cupric chloride.
But this interchange of elements between the cupric sulphate
and the sodium chloride is arrested before the decomposition
of the two salts is complete. A part of each remains unaltered
in the presence of the other and of the two new salts which
are formed. Consequently, the green liquor obtained in this
experiment contains four salts, namely:
Cupric sulphate.
Sodium chloride.
Sodium sulphate.
Cupric chloride.
The respective proportions in which these salts exist in the
mixture depend upon several circumstances. Malaguti has
shown that in cases of this kind it is the energy of the affinity
of the acids for the bases which governs the decomposition.
The most energetic acid tends to combine with the most power-
ful base, and the proportion of the salt thus formed predomi-
nates in the mixture. Thus there is set up, as it were, between
the elements in presence a sort of conflict, in which the stronger
are victorious, while the weaker are not altogether annihilated.
The result is a state of equilibrium which is only disturbed in
case one of the products is by reason of its insolubility removed
from the sphere of action of the other. The latter condition
is realized in the following experiments.
When barium chloride is added to the blue solution of cupric
sulphate, a precipitate of barium sulphate is immediately formed,
and cupric chloride remains in solution, coloring the liquid
green.
CuSO+ BaCl2
BaSO+ CuCl²
Cupric sulphate. Barium chloride. Barium sulphate. Cupric chloride.
In this case the decomposition is complete, owing to the in-
solubility of the barium sulphate. That salt is removed by
cohesion from the sphere of action of the compounds which
remain in solution. The portions first formed, and thus with-
23*
270
ELEMENTS OF MODERN CHEMISTRY.
drawn, are replaced by others, and the reaction once commenced
is finished in the same manner, so that the whole of the cupric
sulphate is converted into barium sulphate.
A concentrated solution of common salt produces no precipi-
tate in a concentrated solution of magnesium sulphate. How-
ever, we must admit that there is an interchange of elements,
and that the liquid contains four salts, namely:
Magnesium sulphate.
Sodium chloride.
Sodium sulphate.
Magnesium chloride.
If this solution be exposed to an intense cold, it deposits
crystals of sodium sulphate, while magnesium chloride remains
in solution (Balard). Of the four salts which are in presence
of each other, the sodium sulphate is the least soluble; it is
therefore deposited, and the double decomposition continues
in the same manner until the greater part of the magnesium
sulphate has been decomposed.
The subject could be further developed by other examples.
Those which have been given are sufficient to expose the true
principle of double decomposition.
We may add that if the operations be conducted in the dry
way and at a high temperature, the volatility of the products
which may be formed exerts an influence upon the reactions
analogous to that which has been established for insolubility.
If an intimate mixture of mercuric sulphate and sodium
chloride be heated in a glass matrass, a sublimate of mercuric
chloride is formed.
HgSO +2NaCl
Na2SO4 + HgCl2
Mercuric sulphate. Sodium chloride. Sodium sulphate. Mercuric chloride.
Action of Soluble Salts upon Insoluble Salts.-The study
of double decomposition may be concluded by a summary ex-
position of the action of soluble salts upon insoluble salts. It
is analogous to that which has just been studied, that is, it is
characterized by a tendency to an interchange of elements. A
single example will be sufficient.
If a solution of sodium carbonate be boiled for a long time
with barium sulphate, it is found that the latter salt has under-
gone a partial decomposition. It is partially converted into
barium carbonate, insoluble like the sulphate, and the liquid
becomes charged with a certain quantity of sodium sulphate.
BaSO³ + Na2CO3
Na2SO + BaCO*
Barium sulphate. Sodium carbonate.
Sodium sulphate.
Barium carbonate.
NITRATES.
271
This decomposition is more complete as the proportion of
sodium carbonate which reacts upon the barium sulphate is
increased. Here, as in some of the preceding experiments, the
influence exerted by the greater mass is very appreciable.
This study may be aptly terminated by summary indications.
upon the composition and properties of the more important
classes of salts, which are the nitrates, sulphates, and carbonates.
NITRATES.
Composition.-Nitric acid containing HNO3, the nitrates
contain the group NO³ combined with a metal which replaces
the hydrogen of the acid. Consequently they contain one or
more groups, NO3, according to the nature of the metal which
has neutralized the nitric acid.
1. KOH +
Potassium hydrate.
HNO3
Nitric acid.
PbO + 2HNO³
Plumbic oxide.
2.
Bi
3.
}
H³
3
0³ 3HNO³
Bismuthic hydrate.
Thus,
KNO3
Potassium nitrate.
+ H2O
Pb(NO3)2 + H2O
Plumbic nitrate.
Bi(NO3)3 + 3H20
Bismuth trinitrate.
With these few examples, we may
conclude:
1. That potassium, which unites with one atom of chlorine
to form potassium chloride, KCl, unites also with one group,
NO³, to form potassium nitrate.
2. That lead, which unites with two atoms of chlorine to
form plumbic chloride, PbCl², unites also with two groups,
NO", to form plumbic nitrate.
3. That bismuth, which unites with three atoms of chlorine
to form bismuth trichloride, BiCP, unites also with three groups,
NO³, to form bismuth trinitrate.
In the chloride K'Cl potassium is monatomic.
In the chloride Pb"C12 lead is diatomic.
In the chloride Bi'C13 bismuth is triatomic.
In the nitrates, these three metals play the same parts as in
the chlorides; and we may say, in a general manner, that the
metallic nitrates contain a metal united with as many times
NO³ as the metal possesses atomicities.
In K'(NO3) monatomic potassium is united with N03
In Pb(NO3)2 diatomic lead is united to 2N03
In Bi'''(NO3)3 triatomic bismuth is united to 3N03
Such is the law of the composition of the nitrates.
272
ELEMENTS OF MODERN CHEMISTRY.
Properties. All of the nitrates are soluble in water. Some
of them are deposited from their solutions in the form of hy-
drated crystals. Such is cupric nitrate, which crystallizes with
six molecules of water at a low temperature.
Others separate in anhydrous crystals. Such are the nitrates
of potassium, sodium, silver, barium, and lead.
All of the nitrates are decomposable by heat, and the pro-
ducts of the decomposition vary with the nature of the nitrate
and with the temperature. Thus, potassium nitrate is first
converted into nitrite, and this is finally decomposed into
nitrogen, oxygen, and potassium oxide. The nitrates of barium
and lead yield nitrogen peroxide, oxygen, and a residue of
oxide. Silver nitrate yields nitrogen peroxide, oxygen, and a
residue of metal.
N²O¹
2AgNO3 = N2O + 0 + Ag
All of the nitrates liberate oxygen when they are heated;
rich in oxygen, they constitute an abundant source of that
element, and they are also easily reduced by bodies possessing
a strong affinity for it.
Sulphur, charcoal, phosphorus, and certain metals are ener-
getically oxidized when heated with the nitrates.
If sulphur be heated with potassium nitrate, potassium
sulphate is formed, and sulphurous oxide and nitrogen are
disengaged.
2KNO³ + S²
Potassium nitrate.
+ SO² + N²
K²SO* + SO²
Potassium sulphate.
When powdered potassium nitrate is thrown upon burning
charcoal, the salt melts and increases the combustion of the
charcoal, producing a vivid deflagration. Potassium carbonate
is formed and carbon dioxide and nitrogen are disengaged.
4KNO³ + 5C
Potassium nitrate.
2K2C0³ + 300² + 2N²
Potassium carbonate.
Distinctive Characters. All of the nitrates deflagrate when
thrown upon incandescent charcoal.
With concentrated sulphuric acid they evolve white vapors of
nitric acid in the cold, and more abundantly when the reaction
is aided by heat. When mixed with copper-filings and treated
with concentrated sulphuric acid, they disengage red vapors.
When the solution of a nitrate is mixed with its own volume
of concentrated sulphuric acid, and a crystal of ferrous sulphate
is introduced into the liquid, the crystal very soon assumes a
SULPHATES.
273
brown color which is communicated to the liquid. In this
very delicate reaction the nitric acid is reduced by the ferrous
sulphate to nitrogen dioxide, which colors the excess of ferrous
sulphate brown (page 154).
The solution of a nitrate, when treated with sulphuric acid,
will decolorize solution of sulphate of indigo when the liquid
is heated to boiling.
SULPHATES.
Composition.-Sulphuric acid, H2SO', contains two atoms
of hydrogen capable of being replaced by a metal. When both
are replaced by an equivalent quantity of metal, a neutral sul-
phate is formed. An acid sulphate is formed when a single
one of these atoms of hydrogen is replaced by a single atom of
metal. The hydrogen of the acid is removed by the oxygen
of the metallic oxide or hydrate which more or less completely
saturates the sulphuric acid. Several cases may be presented.
1. K'OH + H2SO¹
2.
3.
Potassium hydrate.
2K'OH + H2SO
Pb"O + H2SO
Plumbic oxide.
H
K'}
SO¹
Potassium acid sulphate.
+ H2O
K'²SOŁ + 2H2O
Potassium sulphate.
Pb"SO + H2O
Plumbic sulphate.
H2SO¹
SO¹
4. (Al²)O3 +
H2SO¹
vi
(Al) SO+ 3H20
H2SO¹
SO¹
Aluminium oxide.
3 molecules.
Aluminium sulphate.
These examples show that all of the sulphates contain the
group SO, which in sulphuric acid is united with two atoms
of hydrogen. This group is diatomic; it is necessary, then,
that in the sulphates it shall be united with a quantity of metal
equivalent to two atoms of hydrogen.
1. In the acid sulphates it is united with an atom of hydro-
R'
gen and an atom of a monatomic metal, H SO¹.
2. It is united with two atoms of a monatomic metal in the
neutral sulphates R'²SO*.
3. With one atom of a diatomic metal in the neutral sul-
phates M"SO¹.
These cases are very simple. It is not so, however, with
M*
274
ELEMENTS OF MODERN CHEMISTRY.
the fourth, in which we consider the saturation of sulphuric
acid by an oxide R'O³, such as ferric oxide or aluminic oxide.
Each of the three atoms of oxygen of the oxide R20³ removes
H' from a molecule of H2SO, and it results that the metal
which was combined with 30", combines with 3(SO¹)". The
two atoms of metal which are substituted for 3H2 in three mol-
ecules of H³SO¹ are then equivalent to 6 atoms of hydrogen.
They are hexatomic, as is marked by the index vi
Properties. The sulphates are nearly all soluble in water.
Those of barium, strontium, and lead are insoluble. The sul-
phates of calcium and silver, and mercurous sulphate are but
slightly soluble.
The alkaline sulphates, and those of calcium, barium, stron-
tium, magnesium, and lead, are undecomposable by heat. The
others are decomposed at a high temperature. A residue of
oxide generally remains, while sulphurous oxide and oxygen
are disengaged. The sulphates of zinc and copper are thus
decomposed at a high red heat.
CuSO
Cupric sulphate.
SO² + 0 + CuO
Cupric oxide.
In case the oxide is reducible by heat, the residue consists
of metal.
HgSO¹
Hg + SO² + 0²
Mercuric sulphate. Mercury.
3
The sulphates R2(SO4)³ are decomposed at a comparatively
low temperature, disengaging vapor of sulphur trioxide and
leaving a residue of sesquioxide.
Fe² SO¹³
1
Ferric sulphate.
Fe²0³ + 3SO³
Ferric oxide. Sulphuric oxide.
The sulphates are easily reduced by bodies avid of oxygen,
such as charcoal.
If an intimate mixture of potassium sulphate with an excess
of charcoal be heated to bright redness, and allowed to cool out
of contact with the air, a black powder is obtained, which pro-
duces a shower of sparks when projected into the air. It is
the pyrophorous of Gay-Lussac. It owes its spontaneous in-
flammability on contact with the air to finely-divided potassium
sulphide which it contains, and which attracts oxygen with great
avidity. The sulphide is formed according to the following
reaction:
K²SO¹ + 40
Potassium sulphate.
4C0 + K2S
Potassium sulphide.
CARBONATES.
275
In the same manner barium sulphate and calcium sulphate
are converted into sulphides by the action of charcoal at a high
temperature.
The other sulphates are also reduced under the same circum-
stances, but the products vary; carbon dioxide or carbon mon-
oxide and sulphurous oxide are disengaged, and the residue
consists of either oxide or metal.
Distinctive Characters.-When treated by sulphuric acid,
the sulphates do not evolve any gas. They do not deflagrate
when thrown upon burning charcoal. Their solutions give a
white precipitate of barium sulphate with barium nitrate, which
is insoluble in nitric acid. When this precipitate is washed,
dried, and calcined with an excess of charcoal, it leaves a resi-
due of barium sulphide, and when this is moistened with hy-
drochloric acid, it evolves hydrogen sulphide, which is easily
recognized by its odor.
CARBONATES.
Composition.-Carbonic acid is dibasic, like sulphuric acid.
It is not known in the state of hydrate, and the carbonates are
formed by the direct union of carbon dioxide with the metallic
oxides or hydrates.
When freshly-burnt lime is exposed to the air, it attracts at
the same time the moisture and the carbonic acid gas of the air,
and is converted into carbonate.
CO + CaO
CaCO3
Calcium oxide. Calcium carbonate.
The carbonates then contain the group CO³ combined with
a metal. In carbonic acid, this group would be united with two
atoms of hydrogen. The composition of the more simple car-
bonates is expressed by the following formula:
H2CO3 carbonic acid (unknown).
R' CO3 acid carbonates (dicarbonates).
H
R/2CO3 neutral carbonates.
M'CO³ neutral carbonates.
In these formulæ, R' represents a monatomic metal, such as
potassium, which is equivalent to one atom of hydrogen. M"
represents a diatomic metal, such as calcium, which is equiva-
lent to two atoms of hydrogen.
Properties. Only the alkaline carbonates are soluble in pure
276
ELEMENTS OF MODERN CHEMISTRY.
water. The others are insoluble, but they dissolve in water
charged with carbonic acid.
The soluble carbonates possess an alkaline reaction. It is
the same with the acid carbonates of the alkaline metals, which
are ordinarily called bicarbonates, such as potassium dicarbonate
KHCO3.
All of the carbonates except the alkaline carbonates are de-
composable by heat. In this decomposition carbon dioxide is
disengaged, and there remains a residue of oxide, or of metal
in case the oxide be reducible by heat. Thus, the carbonates
of magnesium, calcium, zinc, lead, and copper leave a residue
of oxide after calcination; silver carbonate leaves a residue of
metal.
Barium carbonate is but slowly decomposed at a white heat;
its decomposition is facilitated by heating it in a current of
steam.
Bodies avid of oxygen act upon the carbonates as upon the
oxides; the metal is reduced if the base be reducible. Char-
coal acts in this manner upon the carbonates.
If cupric carbonate be heated with charcoal, carbon dioxide
is disengaged, and metallic copper remains.
2CuCO³ + C = 3C0² + 2Cu
Cupric carbonate.
Copper.
In this experiment carbon dioxide is disengaged, for cupric
oxide is easily reducible by charcoal. It is not the same with
potassium oxide; hence potassium carbonate is only reduced
by charcoal at a very high temperature with disengagement
of carbon monoxide.
K2CO32C3C0+ K²
2
When barium carbonate is heated with charcoal, carbon
monoxide is disengaged in the same manner, but there remains
a residue of barium oxide, for the latter is irreducible by char-
coal.
BaCO3 + C
2CO + BaO
Phosphorus decomposes all of the carbonates.
A small piece of phosphorus may be placed at the bottom
of a small test-tube, and the latter then nearly filled with well-
dried sodium carbonate. The part of the tube containing the
carbonate being heated to redness, the phosphorus may be
heated so that its vapor will pass over the incandescent car-
CLASSIFICATION OF THE METALS.
277
bonate. The latter will be decomposed with the formation of
sodium phosphate and a deposition of carbon. After cooling,
the contents of the tube will be black.
The experiment may be repeated upon calcium carbonate.
The phosphorus is placed in a small crucible, which is then
introduced into a larger one. The calcium carbonate (chalk)
is then placed upon the lid of the smaller crucible, which is
pierced with holes. The arrangement is heated upon a double
grate, so that when the chalk has been brought to incandes-
cence, the vapor of phosphorus may be caused to pass through
it by placing some hot coals upon the lower grate. The chalk
is rapidly decomposed, carbon monoxide is disengaged, and a
mixture of calcium phosphate and phosphide is formed. This
mixture serves for the preparation of hydrogen phosphide.
Distinctive Characters. When treated with sulphuric acid,
the carbonates disengage a colorless, incombustible gas, which
extinguishes burning bodies and produces a milkiness when
agitated with lime-water.
CLASSIFICATION OF THE METALS.
In the preceding pages we have studied the composition and
the general properties of metallic compounds. This study has
revealed the fact that the metals possess very different aptitudes
to form compounds, and various capacities of combination, which
are manifested by the greater or less number of other atoms
which the atoms of these metals can attract.
In this respect,
the differences existing between the metals are analogous to
those which we have already remarked between the metalloids.
On comparing the metals among themselves, some are discov-
ered which resemble each other in the general structure of the
compounds which they are capable of forming, and such can
naturally be classed in the same group. On this plan the
metals are divided into several families analogous to those first
proposed by Dumas for the metalloids, and it will be seen that
the general composition of the metallic compounds furnishes
the elements for a natural classification of the metals. While
this principle is excellent, its application is attended with some
difficulties which chemistry has not yet been able to solve.
Consequently, this chapter must be limited to summary indi-
cations upon the subject.
Some of the metals are incapable of combining with more
24
278
ELEMENTS OF MODERN CHEMISTRY.
than a single atom of chlorine, bromine, or iodine. The com-
pounds thus formed correspond in their atomic constitution to
hydrochloric, hydriodic, and hydrobromic acids. On comparing
potassium chloride or silver chloride to hydrochloric acid, it
will be seen that an atom of potassium or an atom of silver
occupies in them the place occupied by the hydrogen of the
acid. The atoms of potassium and of silver are therefore
equivalent to the atoms of hydrogen as far as their capacity
of combination is concerned. The other alkaline metals, such
as sodium and lithium, are similar and belong to the same group.
Their chlorides, bromides, and iodides, which are arranged in the
following table, present analogous compositions:

MONATOMIC METALS.
MONATOMIC MONATOMIC
CHLORIDES. BROMIDES.
MONATOMIC
Iodides.
II'CI
I'Br
HI
Potassium K'
KCI
KBr
ΚΙ
Sodium Na'
NaCl
NaBr
NaI
Lithium Li'
LiCl
LiBr
Lil
•
Silver Ag'.
AgCl
AgBr
AgI
These metals form oxides whose atomic constitutions corre-
spond to that of water, each containing two atoms of metal for
one of oxygen. Their sulphides correspond to hydrogen sul-
phide, containing two atoms of metal for one of sulphur. With
the oxides and sulphides we may group the hydrates and
sulphydrates, which possess analogous atomic constitutions.
OXIDES.
K20
Na20
Ag20
TYPE H2O.
HYDRATES.
KOH
NaOH
TYPE H2S.
MONOSULPHIDES. SULPHYDRATES.
K2S
Na2S
KSH
NaSII
Ag2S
The same analogy is continued between the salts of these
metals, as will be seen from the nitrates and sulphates which
we take as examples.
NITRIC ACID, HNO3.
SULPHURIC ACID, H2SO4.
NITRATES.
KNO3
NaNO3
AgNO3
SULPHATES.
ACID SULPHATES.
K2SO4
Na2SO4
KIISO¹
NaHSO4
Ag2SO4
CLASSIFICATION OF THE METALS.
279
It is seen that in all of these compounds the metals under
consideration replace hydrogen atom for atom; each of them
possesses the same capacity of combination as that gas. They
are said to be monatomic.
Certain other metals manifest a double capacity of combina-
tion; one atom of any of these is capable of replacing two
atoms of hydrogen, consequently it can combine with two
atoms of chlorine, bromine, or iodine, or with one atom of
oxygen or sulphur. In the chlorides of these metals, the two
atomicities of the metal are satisfied by the two atomicities of
two atoms of chlorine. In their oxides, the two atomicities
of the metal are satisfied by the two atomicities or bonds of
affinity which reside in one atom of oxygen. These metals are
then diatomic. They are quite numerous and can be divided
into several groups, one of the most natural of which com-
prises barium, strontium, calcium, and lead. The following
table shows the constitution of the principal compounds of
these metals:
DIATOMIC METALS. CHLORIDES.
OXIDES.
NITRATES. SULPHATES.
21ICI
H20
2HNO3
H2SO4
Barium Ba"
BaCl2
BaO
Ba(NO3)2 BaSO
Strontium Sr".
SrCl2
Sro
Sr(NO3)2
SrS04
Calcium Ca"
Ca C12
CaO
Ca(NO3)2
CaSO¹
Lead Pb"
PbC12
РЬО
Pb(NO3)2 PbS04
The metals of this group combine with oxygen in two pro-
portions, forming not only the monoxides, RO, but also the
dioxides, RO2. They thus form two oxides, while they are
capable of forming but one chloride, RCP. Thus, barium
forms a monoxide, BaO, a dioxide, BaO2, and a dichloride,
BaCl2; but no tetrachloride of barium is known, and it is not
probable that barium can act as a tetratomic element. How is
it, then, that in the dioxide this metal can combine with two
atoms of oxygen, while it cannot combine with four atoms of
chlorine, which are equivalent to two atoms of oxygen? In
other words, what is the atomicity of barium in the dioxide
which would seem to correspond to a tetrachloride? It is
280
ELEMENTS OF MODERN CHEMISTRY.
undoubtedly diatomic in the dioxide as it is in the monoxide,
and the constitution of barium dioxide is analogous to that of
hydrogen dioxide, which has already been indicated. The
two atoms of oxygen mutually satisfy two of their atomicities
by combining together, and they retain two which are neutral-
ized in combining with the diatomic atom of barium. Thus,
in barium monoxide one atom of oxygen is joined to one atom
of barium by both of its atomicities; in the dioxide two atoms
of oxygen are united to one atom of barium, each by one atom-
icity. If we represent the saturation of two atomicities by a
straight line, as has before been explained, we will have the
following formulæ :
Ba=0
Barium monoxide.
Ba
0-0
Barium dioxide.
In this manner, theory enables us to fix the relations existing
between the atoms in a given body.
The comparison may be continued between the other diatomic
metals. Magnesium, the radical of magnesia, somewhat resem-
bles calcium in its relations, and forms, as it were, the centre
of a group including magnesium, zinc, cobalt, and nickel, and
which is called the magnesium group. Manganese and iron, on
one hand, and copper, on the other, seem to join this group by
certain of their characteristics. In their most stable and gen-
erally their most important compounds, these metals act as
diatomic elements. All form the dichlorides RC1 and the
oxides RO. But in other compounds, manganese and iron
seem removed from the metals of this group, and resemble
chromium and aluminium. Copper, which resembles magne-
sium in the series of cupric compounds, approaches mercury
in the cuprous series.
Bismuth, which might be classed with antimony, and gold
are triatomic in their most important combinations. They
form the chlorides BiCl³ and AuC¹³.
A certain number of the metals may be grouped together as
tetratomic, since they manifest four atomicities in their principal
combinations. They are tin, titanium, and zirconium. They
form the chlorides RCI and the oxides RO². In stannic chlo-
ride, SnCl4, the tin is saturated with chlorine, of which it
cannot combine with more than four atoms; it is tetratomic
in this saturated compound. But it may combine with only
CLASSIFICATION OF THE METALS.
281
two atoms of chlorine, thus forming the chloride SnCl2,
which is not saturated, for it can still fix two more atoms
of chlorine. Tin only manifests two atomicities in the
dichloride.
In the same manner, ferrous chloride, FeCl2, can absorb
chlorine, becoming ferric chloride. The latter contains two
atoms of iron and six of chlorine. These two atoms of iron
exist in all the ferric compounds; together they manifest six
atomicities, for in ferric chloride they are united with six atoms
of chlorine. They constitute a hexatomic couple.
COMPOUNDS.
CHLORIDES.
OXIDES.
SULPHATES.
Ferric
Fe2C16
Fe203
Fe2(SO4)3
Manganic
Mn2C16
Mn203
Mn2(SO4)3
Chromic
Cr2C16
Cr203
Cr²(SO4)3
Aluminic
A12C16
A1203
Al2(SO4)3
The following table gives a résumé of the constitution of the
principal metallic combinations. The metals there chosen as
examples have different atomicities. The hexatomic couple,
consisting of two atoms of iron, may for convenience be called
ferricum.


METALS.
CHLORIDES. OXIDES. NITRATES. SULPHATES.
Monatomic metal-Potassium K'
KCI
Diatomic metal-Barium Ba".
BaCl2
K20 KN03
BaO Ba(NO3)2 BaSO¹
K2SO4
Triatomic metal-Bismuth Bi"
B:C13
Tetratomic metal-Tin Sniv
SnCl4
Bi203 Bi(NO3)3 Bi2(SO4)3
Sn02
•
Fe203 Fe2(NO3,6 Fe2(SO4)3
Hexatomic group-Ferricum (Fe2)vi Fe2C16
Such are the principles furnished by the theory of atomicity
for a rational classification of the metals.
24*
282
ELEMENTS OF MODERN CHEMISTRY.
POTASSIUM.
K = 39.1.
Potassium was discovered by Sir Humphry Davy in 1807.
It ordinarily occurs in commerce in gray, globular masses,
readily yielding to the pressure of the nail. It has a dull,
tarnished appearance, but when freshly cut it exposes a brilliant
surface. It is the metallic radical of potash.
If a fragment of this metal be thrown into water, it at once
takes fire and rushes about on the surface of the liquid, burn-
ing with a violet flame. Finally, it disappears with a little
explosion.
This brilliant phenomenon is due to the energy with which.
potassium decomposes water.
2H²0 + K² = 2KOH + H²
The hydrogen which is disengaged is inflamed by the incan-
descent metal. The potassium hydrate formed ultimately dis-
solves in the water, but its temperature being very high at the
moment of its solution, and its combination with the water
also producing heat, there results a sudden formation of steam,
which gives rise to the little explosion.
Preparation and Properties.-Potassium is prepared by
decomposing potassium carbonate by carbon at a high tempera-
ture.
K2CO3 + 20
Potassium carbonate.
3C0 + K²
Carbon monoxide.
The mixture is heated to whiteness in an iron retort and the
vapors are passed into a copper receiver. The potassium dis-
tils and condenses in globules or irregular masses, still contain-
ing charcoal and a black substance. It is purified by redistilla-
tion in an iron retort, and is condensed in a copper receiver
filled with naphtha. The manufacture of potassium is a dan-
gerous operation. It is accompanied by the formation of
various accessory products, among which is a black substance
which sometimes explodes spontaneously on contact with the
air.
Potassium melts at 62.5° (Bunsen). It boils at a red heat,
and its vapor is green. When exposed to the air, it rapidly
absorbs oxygen and at the same time decomposes the atmos-
pheric moisture. It inflames at a temperature but slightly
elevated and becomes converted into oxide.
POTASSIUM OXIDES.-POTASSIUM HYDRATE. 283
POTASSIUM OXIDES.
Potassium monoxide, K'O, is formed when thin pieces of
the metal are abandoned to the action of dry air, or when
potassium hydrate is heated with potassium.
2KOH + K²
2K²0 + H²
It is a grayish-white substance which unites with water with
extreme violence, forming potassium hydrate.
K2O + H2O 2KOH
A tetroxide of potassium, K'O¹, is formed when potassium
is heated in an excess of oxygen, but it is little known.
POTASSIUM HYDRATE, OR CAUSTIC POTASSA.
KOH
This important compound is prepared by boiling 1 part of
potassium carbonate with 12 parts of water, and gradually add-
ing milk of lime to the boiling liquid. The lime combines
with the carbonic acid forming an insoluble carbonate, while
the potassa remains in solution.
K²CO³ + Ca(OH)²
CaCO³ + 2КОН
Calcium hydrate. Calcium carbonate.
When the decomposition is finished the liquid is allowed to
settle, and the clear solution decanted and rapidly evaporated.

FIG. 97.
The residue is melted in a silver dish and poured out upon flat
stone slabs or cast in cylindrical metallic moulds (Fig. 97).
This product is known as potash by lime. It is impure.
By treating it with alcohol, which dissolves only the potassium
284
ELEMENTS OF MODERN CHEMISTRY.
hydrate, it may be purified from lime, and the salts of potas-
sium it may contain, and especially the carbonate, which is
formed by the absorption of carbonic acid gas from the air
during the evaporation. The clear alcoholic solution is decanted,
and after the alcohol has been expelled by distillation, the resi-
due is evaporated to dryness and fused in a silver dish. It is
known as potash by alcohol.
Recently-fused potassium hydrate occurs as opaque, white
fragments having a short fibrous fracture and a density of 2.1.
It melts at a red heat and volatilizes at whiteness; it is not
decomposed by heat. When exposed to the air, it absorbs moist-
ure and carbonic acid gas, and deliquesces. It is very soluble
in water, and produces heat in dissolving. A hydrate, KOH
+ 2H2O, is deposited from its hot and very concentrated solu-
tion in acute rhombohedra.
Potassium hydrate is decomposed by iron at a white heat:
oxide of iron is formed, and hydrogen and potassium vapor are
disengaged. Gay-Lussac and Thenard founded a process for
the preparation of potassium on this decomposition. Until then
the metal had only been obtained in small quantities by Davy
by the electrolysis of potassium hydrate.
Potassium hydrate is very caustic. It softens and destroys
the skin, and for this purpose is employed in surgery as a caustic.
It manifests the properties of an alkali in the highest degree;
these are its solubility in water, its power to neutralize the
acids and decompose a great number of metallic solutions, and
its corrosive action on the tissues. This alkalinity may be shown
by the energy with which the most feeble solutions of potassa
restore the blue color to reddened litmus, and change to green
the tincture of violets.
SULPHIDES OF POTASSIUM.
Potassium will burn in vapor of sulphur. It unites with
the latter body in five different proportions, forming the sul-
phides K'S, K2S2, K2S³, K2S4, and K2S5.
Potassium monosulphide is formed when potassium sulphate
is heated to redness in a current of hydrogen, or in a brasqued¹
and covered crucible with charcoal.
1 A brasqued crucible is a clay crucible into which powdered charcoal
moistened with gum-water has been strongly pressed, and afterwards cal-
cined. The substance to be reduced is placed in a cavity hollowed out in
the charcoal,
POTASSIUM CHLORIDE.—POTASSIUM IODIDE. 285
K2SO4 + 4C
Potassium sulphate.
4C0+ K2S
Potassium monosulphide.
A reddish, deliquescent, and caustic mass is thus obtained.
When a mixture of sulphur and potassium carbonate is fused,
carbon dioxide is disengaged, and a brown mass is obtained on
cooling, which is known as liver of sulphur. It is a mixture
of potassium polysulphide with undecomposed carbonate and
potassium sulphate or hyposulphite, according to the tempera-
ture and the proportions of sulphur which have been employed.
With an excess of sulphur, potassium pentasulphide is obtained.
Liver of sulphur dissolves in water with a brown-yellow color.
Potassium pentasulphide and hyposulphite are also formed
when potassium hydrate is boiled with an excess of flowers of
sulphur. The filtered solution is brown. When treated with
hydrochloric acid, it evolves hydrogen sulphide, and finely-
divided, yellowish, pulverulent sulphur is deposited.
K2S5 + 2HCI
2KCl + H2S + S¹
POTASSIUM CHLORIDE.
KCI
This salt is found crystallized in cubes in the neighborhood
of certain fissures of Vesuvius, and in thin layers in the saline
deposits at Stassfurth, Prussia, and in other localities. At
Stassfurth there is found a double chloride of potassium and
magnesium, KCl,MgCl2 + 6H2O. When this double salt is
dissolved in hot water, the greater part of the potassium
chloride is deposited on cooling while the magnesium chloride
remains in solution.
Potassium chloride crystallizes in cubes, but it sometimes
separates in octahedra from solutions containing free potassa.
It is unaltered by the air. Its taste is analogous to that of
sodium chloride; it is more soluble in water than the latter,
and produces a greater depression of temperature in dissolving.
1 part of chloride of potassium dissolves in 3 parts of water
at 17.5°. 100 parts of water at 0° dissolve 29.23 parts of
potassium chloride and 0.2738 additional for each degree of
temperature.
POTASSIUM IODIDE.
ΚΙ
This compound is quite important on account of its use in
medicine. It is obtained by adding powdered iodine to solution
286
ELEMENTS OF MODERN CHEMISTRY.
of potassium hydrate until the latter is completely neutralized.
Potassium iodide and iodate are formed, the latter being pre-
cipitated. The whole is evaporated to dryness, and the residue
heated to redness, by which the iodate is converted into iodide.
The mass is redissolved in boiling water and the solution con-
centrated; fine cubical crystals of potassium iodide are obtained
on cooling.
These crystals are opaque and anhydrous. They melt at a
red heat without decomposition; their taste is salty and some-
what bitter. 100 parts of water at 18° dissolve 143 parts of
potassium iodide.
A solution of potassium iodide dissolves iodine abundantly,
assuming a dark-brown color.
If nitric acid be added to a solution of potassium iodide,
iodine is at once deposited and red vapors are disengaged if
the solution be concentrated (page 131).
C
This decomposition of potassium iodide takes place even in
very dilute solutions. It may serve for the detection of the
smallest trace of this salt if a solution of starch be previously
added to the liquid; in this case a blue color will be produced.
Potassium bromide is prepared by a process similar to that
which yields potassium iodide. It crystallizes in cubes which
are soluble in about 1.5 parts of cold water.
POTASSIUM NITRATE.
KNO3
This important salt, long known as nitre and saltpetre, im-
pregnates the soil and sometimes effloresces upon its surface in
certain regions of India, Egypt, Persia, Hungary, and Spain.
In the United States, it is found in many localities, generally
in caverns in limestone rock, called saltpetre caves. It is
obtained by lixiviating the earthy matters containing it and
evaporating the solution.
It is less abundant in northern climates. It is formed
wherever nitrogenized organic substances decompose in pres-
ence of potassa. Thus, it exists in small quantities in the soil
of cellars, in moist walls, and in the débris of demolitions.
In these cases it is mixed with a certain quantity of sodium
nitrate and a large excess of calcium and magnesium nitrates.
Formerly such materials were lixiviated to obtain the nitrates,
all of which were then converted into potassium nitrate. Nitre
is also manufactured artificially by exposing to the air mixtures
POTASSIUM NITRATE.
287
of animal matters with wood-ashes and lime which are fre-
quently moistened with stale urine or stable-drainings. How-
ever, a great part of the potassium nitrate employed in the
arts is now obtained from the natural sodium nitrate of Peru.
Two processes are employed.
One consists in adding the sodium nitrate to a concentrated
boiling solution of potassium carbonate: sodium carbonate
being less soluble than the latter, is precipitated and continues
to deposit during the concentration; it is removed, and the
potassium nitrate, which is very soluble in hot water, crystal-
lizes out on cooling.
The second process consists in decomposing the sodium nitrate
with potassium chloride. The saturated and boiling mixture
of the two solutions deposits sodium chloride, which is sepa-
rated, and the potassium nitrate crystallizes on cooling.
Properties. This salt crystallizes from its aqueous solution
in long, six-sided prisms, terminated by six-sided pyramids. Gen-
erally these crystals are grooved or striated. They belong to the
right rhombic system. Their taste is cooling and slightly bitter.
Potassium nitrate melts at about 350°; at a higher tem-
perature it disengages oxygen and is converted into potassium
nitrite, KNO2, which is in its turn decomposed at a red heat,
leaving a mixture of oxide and peroxide of potassium.
Potassium nitrate is very soluble in hot water: 100 parts of
water at 0° dissolve only 13.32 parts of the salt, but at 18° they
dissolve 29 parts; at 97°, 236 parts; and at 100°, 246 parts.
The facility with which potassium nitrate parts with its oxy-
gen, of which it contains nearly half its weight, renders it an
energetic oxidizer of many bodies.
If a small quantity of pulverized saltpetre be thrown upon
glowing coals, the salt melts and decomposes, increasing the
combustion at the point of contact with the fuel: it is said to
deflagrate upon hot coals. The nitrate becomes converted into
carbonate.
Gunpowder is an intimate mixture of saltpetre, charcoal,
and sulphur. As is well known, the combustion of this sub-
stance is instantaneous, and gives rise to the sudden formation.
of gaseous products. The decomposition may be expressed
generally by stating that the charcoal combines with the oxy-
gen of the nitre to form carbon dioxide and carbon monoxide;
the nitrogen is liberated, and the sulphur combines with the
potassium forming potassium sulphide. As the mixture con-
288
ELEMENTS OF MODERN CHEMISTRY.
tains all of the oxygen necessary for its own combustion, the
latter can be effected in a limited and closed space. It can
readily be understood that the explosive energy of the powder
is due to a sudden evolution of gas occupying many times the
volume of the powder, and of which the volume is still further
augmented by the high temperature.
POTASSIUM SULPHATE.
K2SO⭑
This salt is obtained as a by-product in various industrial
operations. It deposits from the mother-liquors of the soda
from sea-weed when these are exposed to low temperatures. It
may be made by saturating with potassium carbonate the potas-
sium acid sulphate which is formed in the preparation of nitric
acid by the decomposition of potassium nitrate with sulphuric
acid, a process which is now but little employed.
It crystallizes in four-sided prisms or in double, six-sided
pyramids belonging to the orthorhombic system. These crys-
tals are hard, anhydrous, unaltered by the air, and melt at a
red heat without decomposition. They are but slightly soluble
in water and insoluble in absolute alcohol. 100 parts of water
at 0° dissolve 8.36 parts, and 0.1741 part for each additional
degree of heat.
POTASSIUM ACID SULPHATE.
K } So
H
This salt may be obtained by fusing 13 parts of the neutral
sulphate with 8 parts of concentrated sulphuric acid. The
saline mass is dissolved in boiling water, and the solution when
properly concentrated deposits rhombic octahedra or tabular
crystals belonging to the orthorhombic system.
Potassium acid sulphate is much more soluble in water than
the neutral salt; its solution is acid. When strongly heated,
it first gives up water and then sulphuric oxide, leaving a resi-
due of neutral sulphate.
POTASSIUM CHLORATE.
KC103
This salt is formed, together with potassium chloride, by the
action of chlorine upon a concentrated solution of potassium
hydrate or carbonate:
6Cl + 6KOH
KCIO³ + 5KCl + 3H20
POTASSIUM PERCHLORATE.
289
It is less soluble than the chloride, and is consequently de-
posited in great part as the solution becomes saturated with
chlorine. It is purified by several recrystallizations.
In the arts, it is obtained by the action of chlorine upon a
mixture of lime, potassium chloride, and water, heated in closed
vessels. Chlorate and chloride of calcium are formed, and in
presence of the potassium chloride, a double decomposition takes
place, potassium chlorate and calcium chloride, which is very
soluble, being formed. The liquid is filtered hot, and the potas-
sium chlorate crystallizes out on cooling.
KC +
3CaO + 3C1²
Calcium oxide.
KC10³ + 3CaCl²
Calcium chloride.
Potassium chlorate crystallizes in colorless, rhomboidal tables.
When very thin they present an iridescent reflection. It melts
at 400°, and at a higher temperature is decomposed into oxygen
and chloride and perchlorate of potassium, the latter of which
is also decomposed when the temperature is raised still further.
2KCIO³ KC KCIO¹ + O²
KCIO¹ KCl + 0
Potassium chlorate deflagrates when thrown upon hot coals;
when mixed with sulphur, it explodes by friction or percussion;
the detonation becomes dangerous if the sulphur be replaced
by phosphorus.
It is not very soluble in cold water.
100 parts of water at
0° dissolve 3.3 parts, and at 24°, 8.44 parts. It is much more
soluble in boiling water.
POTASSIUM PERCHLORATE.
KCIO+
This salt is formed by the action of either heat or sulphuric
acid upon potassium chlorate (page 124). It is but slightly
soluble in water, requiring 65 parts at 15° for its solution. It
crystallizes in anhydrous and transparent right rhombic prisms.
Above 400° it decomposes into potassium chloride and oxygen.
POTASSIUM CARBONATES.
Potassium Neutral Carbonate, K CO-This carbonate.
is found in commerce under the simple name potash, and is
known according to its source as Russian or American potash.
N
25
290
ELEMENTS OF MODERN CHEMISTRY.
It is obtained by lixiviating wood ashes; that is, exhausting
them with water, evaporating the solution to dryness, and cal-
cining the residue in the air. The potash thus obtained is
impure carbonate mixed with other salts of potassium, princi-
pally the chloride and sulphate, and small quantities of silicate.
It contains from 60 to 80 per cent. of carbonate.
Potassium carbonate is now manufactured from the native
chloride, Stassfurth salt, by a process similar to that which will
be described for the manufacture of sodium carbonate from
common salt.
Pure potassium carbonate may be prepared by calcining potas-
sium acid tartrate, or cream of tartar, at a red heat. A black
mass is thus obtained from which water dissolves pure potas-
sium carbonate, and the solution is evaporated to dryness.
Neutral potassium carbonate is very soluble in water, and
absorbs moisture from the air. 1 part of the anhydrous salt
dissolves in 1.05 parts of water at 3°, and in 0.49 parts at 70°
(Osann). The solution has a decided alkaline reaction.
very concentrated hot solution deposits rhombic octahedra
containing K2CO3 + 2H2O on cooling.
A
Potassium Acid Carbonate, KHCO³.-When a current of
carbonic acid gas is passed into a concentrated solution of potas-
sium neutral carbonate, the gas is absorbed, and crystals of
potassium acid carbonate, ordinarily known as bicarbonate of
potassa, are formed.
It represents carbonic acid in which a single atom of hydro-
gen is replaced by an atom of potassium.
II2CO3 carbonic acid (hypothetical).
CO2 + H2O
CO2 + KHO
H
CO2 + K20
CO³ potassium acid carbonate.
K2CO3 potassium carbonate.
Potassium acid carbonate readily crystallizes in oblique rhom-
bic prisms. It is much less soluble in water than the neutral
carbonate, and its solution disengages carbonic acid gas on
boiling. Its reaction is alkaline.
Characters of Potassium Salts.-The salts of potassium
communicate a violet tint to flame. Their solutions are not
precipitated either by hydrogen sulphide, ammonium sulphide,
or sodium carbonate.
Perchloric acid occasions a white precipitate of potassium
perchlorate.
SODIUM.
291
Platinum tetrachloride produces a yellow, crystalline precipi-
tate of platinum and potassium double chloride, 2KCl. PtCl
Hydrofluosilicic acid forms a white, gelatinous precipitate
consisting of potassium fluosilicate.
SODIUM.
Na 23
Sodium was discovered by Sir Humphry Davy in 1807. It
is made by decomposing sodium carbonate with charcoal, a
certain proportion of chalk being added to render the mixture
infusible. The operation is conducted in large cast-iron cylin-

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FIG. 98.
ders covered with a refractory luting to enable them to resist
the high temperature required to effect the decomposition.
The vapor passes into a flattened receiver in which the sodium
condenses, and from which it runs into appropriate vessels
(Fig. 98).
292
ELEMENTS OF MODERN CHEMISTRY.
ན
This metal is soft at the ordinary temperature. It has a
silvery lustre, melts at 90.6°, and distils at a red heat. It is
not as avid of oxygen as potassium; it can be melted in the
air without taking fire. When thrown upon water, it melts
and runs around on the surface, producing a hissing noise.
The water is decomposed with disengagement of hydrogen and
the formation of sodium hydrate. The reaction is analogous
to that of potassium upon water, but is less energetic; fre-
quently, however, it terminates by an explosion.
If sodium be thrown upon hot water, or water which has
been thickened with gum or starch, so that the consistence
of the liquid may prevent the globule from moving rapidly,
the latter becomes sufficiently heated to ignite the hydrogen
evolved, which then burns with a yellow flame.
The compounds of sodium are widely diffused in nature, and
generally present great analogies with the corresponding potas-
sium compounds.
OXIDES AND HYDRATE OF SODIUM.
Two oxides of sodium are known, a monoxide, Na2O, and a
dioxide, Na2O².
Sodium hydrate, NaOH, is frequently employed in the lab-
oratory and in the arts under the name caustic soda. It is
prepared by decomposing a rather dilute, boiling solution of so-
dium carbonate by milk of lime, in the manner described for
the preparation of potassium hydrate (page 283). It occurs
as a white solid, which attracts moisture and carbonic acid
from the air, and finally 'becomes transformed into a dry mass
of carbonate. Sodium hydrate is freely soluble in water, and is
very caustic. It is known in commerce as concentrated lye.
SODIUM SULPHIDE AND SULPHYDRATE.
Sodium sulphile, Na'S, is prepared by the following pro-
cess: A concentrated solution of sodium hydrate is divided
into two equal parts; one part is then saturated with hydrogen
sulphide, sodium sulphydrate being formed.
NaOH
+ H2S
Sodium hydrate.
NaSH + H2O
Sodium sulphydrate.
SODIUM CHLORIDE.
293
To this sulphydrate the other portion of sodium hydrate is
added, and the solution is concentrated out of contact with the
air. Hydrated crystals of sodium sulphide are deposited.
NaSH+ NaOH = H2O + Na2S
These crystals are rectangular prisms terminated by four-
faced points. When pure, they are colorless; they are very
soluble in water.
SODIUM CHLORIDE.
NaCl
This body is common salt, or sea-salt.
It is widely diffused
in nature. It is found in the solid state, as rock-salt, in large
deposits in many countries.
Sea-water contains a large proportion of sodium chloride,
and this salt also exists in a number of mineral waters, of
which it forms the most abundant constituent.
In France, the greater portion of the salt delivered to com-
merce is obtained by the evaporation of sea-water in the salt-
marshes near the ocean, and the salt-basins along the Mediter-
ranean. These are extensive basins into which the water is
led from the sea, and where it forms a shallow layer, which is
continually swept by the summer winds. It thus becomes con-
centrated, and the concentration is favored by the water being
continually kept in motion from one basin to another, until it
arrives in the areas where the salt is deposited. The mother-
liquors, from which the sodium chloride is separated, and which
are still saturated with that salt, contain, in addition, magne-
sium sulphate and salts of potassium. By cooling them to a
low temperature sodium sulphate is obtained, being formed by
a double decomposition between the sodium chloride and the
magnesium sulphate. The new mother-liquor then deposits,
first, potassium and magnesium double sulphate, and after-
wards, magnesium and potassium double chloride (Balard). It
was in the latter of these liquors that Balard discovered bro-
mine in 1826.
Sodium chloride is also obtained by the evaporation of the
waters of salt springs. The operation is conducted in large
sheet-iron boilers; the salt crystallizes from the hot liquid, and
a double sulphate of calcium and sodium, which is but slightly
soluble, deposits in the basins in the course of time.
25*
294
ELEMENTS OF MODERN CHEMISTRY.
Sodium chloride crystallizes from its aqueous solution in
cubes. The crystals are generally small, and a great number
of them frequently become agglomer-
ated in symmetrical hopper-like masses
(Fig. 99). These crystals are anhy-
drous, but contain a small quantity of
interposed water; when heated they
decrepitate, because this water is vola-
tilized and suddenly separates the crys-
tals. Rock-salt is sometimes found in
transparent cubes, sometimes in octahedra and intermediate
forms. Sodium chloride fuses at a red heat and solidifies to a
crystalline mass on cooling. It volatilizes at a white heat. It
very soluble in water, and its solubility does not increase with
the temperature. According to Gay-Lussac,

is
FIG. 99.
1 part of common salt dissolves in 2.78 parts of water at 14°
(C
2.7
2.48
60°
109.7°
The saturated solution boils at 109.7°; its density at 8° is
1.205. Sodium chloride is insoluble in absolute alcohol.
SODIUM SULPHATE.
Na2SO4
This salt is obtained in the arts by decomposing common salt
with sulphuric acid (page 117).
This operation, which constitutes the first step in the manu-
facture of sodium carbonate, is conducted in a reverberatory
furnace, connected with a suitable apparatus for the condensa-
tion of the hydrochloric acid which is disengaged. Sodium
acid sulphate is first formed, and at a higher temperature this
reacts upon another molecule of sodium chloride.
SO¹
Naso + NaCl
}}
H
Sodium acid sulphate.
Na2SO4 + HCl
Sodium sulphate.
Sodium sulphate is now extensively produced by subjecting
the mother-liquors from the manufacture of salt from sea-water
to intense cold.
It crystallizes from water in four-sided, oblique rhombic
prisms, containing 10 molecules of water of crystallization;
SODIUM CARBONATE.
295
these crystals effloresce in the air. They possess a bitter, salty,
and disagreeable taste. They are very soluble in water, and
the temperature of their maximum solubility is 33°. Accord-
ing to Gay-Lussac,
100 parts of water at 0° dissolve 12 parts of sodium sulphate.
18°
((
25°
(C
48
100
""
(C
33°
(6
50°
(6
332.6
263
66
(6
When the solution saturated at 33° is heated, it deposits an-
hydrous sodium sulphate in orthorhombic octahedra, analogous
to the anhydrous sodium sulphate found in nature (thenardite).
Sodium Acid Sulphate, Ni} SO-This salt may be ob-
tained by dissolving in water the requisite proportions of so-
dium neutral sulphate and sulphuric acid. On cooling the
saturated solution, oblique rhombic prisms are obtained, which,
according to Mitscherlich, contain two molecules of water of
crystallization. These crystals are very soluble in water, and
have an acid taste. Alcohol decomposes them into sulphuric
acid, which dissolves, and neutral sulphate, which precipitates.
SODIUM CARBONATE.
Na2CO3
This important salt, known also as soda and sal-soda, is
manufactured on an immense scale in the arts. It is used in
the manufacture of soap and glass, for washing, and many other
purposes. It was formerly obtained from the ashes of fuci,
algæ, and other sea-plants which furnished Alicant soda. It
is now most generally prepared from sodium chloride, and the
process, which is due to Le Blanc, consists of three distinct
operations: 1st, the transformation of the sodium chloride
into sulphate by sulphuric acid; 2d, the conversion of the sul-
phate into carbonate by calcination with a mixture of chalk
and coal; 3d, lixiviation of the calcined mass and evaporation
of the solution. Only the latter two operations need be de-
scribed here: they are conducted in reverberatory furnaces,
of which the doubly-arched roofs are licked by the flame of
the combustible (Fig. 100).
296
ELEMENTS OF MODERN CHEMISTRY.
A mixture of 1000 parts of sodium sulphate, 1040 parts of
chalk, and 580 parts of coal, is first introduced into compart-
ment B of the furnace, where it is dried. It is then transferred
to compartment A, where the temperature is very elevated,
and where the sodium sulphate is reduced to sulphide by the

FIG. 100.
coal. The sodium sulphide and chalk react upon each other,
forming sodium carbonate and calcium sulphide (Kolb).
The results of the reaction may be expressed by the follow-
ing equation:
Na2SO + CaCO3 + C4 Na2CO3 + CaS+4CO.
There are, however, certain secondary reactions which take
place at the same time; thus, a certain quantity of sodium
oxide is formed by the action of the coal upon the carbonate.
Na2CO3 + C = 2CO + Na2O
When the incandescent mass has become pasty, it is removed
from the furnace, reduced to powder, and thoroughly lixiviated.
The water dissolves the sodium carbonate, and leaves the in-
soluble calcium sulphide, which remains mixed with the lime
produced by the decomposition of the excess of chalk employed
(Gossage, Scheurer-Kestner). The solutions are concentrated
in the boiler D, heated by the waste heat from the soda fur-
nace. Finally, they are drawn off into the compartment C,
where they are evaporated to dryness. The sal-soda of com-
merce is thus obtained. When the properly-concentrated solu-
tion is allowed to cool, the crystallized soda of commerce is
deposited.
Another process, proposed by Schlosing and Rolland, is also
used for the fabrication of sodium carbonate.
SODIUM CARBONATE.
297
It depends upon the double decomposition which takes place
between ammonium acid carbonate and sodium chloride in
concentrated aqueous solution.
NaCl + (NH*)HCO3 = NH*Cl + NaHCO3
+
The sodium acid carbonate, which is but slightly soluble, is
precipitated; it is collected and converted into the neutral car-
bonate by the action of heat.
2NaHCO³ Na2CO3 + CO2 + H2O
It thus loses half of its carbonic acid, which is utilized for
the preparation of a new quantity of ammonium acid carbonate.
The other portion of the carbonic acid necessary for this oper-
ation is produced by the calcination of lime-stone (calcium car-
bonate), which at the same time yields the lime necessary for
the liberation of the ammonia contained in the mother-liquor
in the form of ammonium chloride.
A considerable quantity of sodium chloride is also manufac-
tured from cryolite, which is a double fluoride of sodium and
aluminium, and of which large deposits exist in Greenland.
The mineral is calcined with lime, calcium fluoride and alumi-
nate of soda being formed.
Al2F16,6NaF1 + 6CaO
Cryolite.
6CaFl² + Aľ²О³,3Na²O
Calcium fluoride.
Aluminate of soda.
The latter compound is dissolved out by water and decom-
posed by carbonic acid gas, aluminium oxide being precipitated
and sodium carbonate remaining in solution.
Sodium carbonate crystallizes in oblique rhombic prisms,
containing 10 molecules of water of crystallization. When
heated, they fuse in this water of crystallization, which they
then abandon; they also lose it by efflorescence when exposed
to the air.
Sodium carbonate is very soluble in water, and the solution
has a strongly alkaline reaction. According to Poggiale,
100 parts of water at 0° dissolve 7.08 parts of sodium carbonate.
66
10°
(C 20°
25°
(C
16.06
25.93
((
30.83
(6
(" 30°
35.90
"(
" 104.6°
48.5
The saturated solution boils at 104.6°. Sodium carbonate
is insoluble in alcohol.
N*
298
ELEMENTS OF MODERN CHEMISTRY.
Sodium Acid Carbonate, NaHCO³.-When carbonic acid
gas is passed into a solution of sodium carbonate or over
crystals of that salt, the gas is absorbed and sodium acid car-
bonate, commonly called bicarbonate of soda, is formed. This
salt crystallizes in oblique, four-sided prisms, shortened into the
form of tables. Its taste is salty and slightly alkaline. It is
less soluble in water than the neutral carbonate. It restores
the blue color to reddened litmus; its solution does not pre-
cipitate that of magnesium sulphate. When boiled, it loses
carbonic acid, neutral carbonate being formed.
PHOSPHATES OF SODIUM.
There are three phosphates of sodium derived from ordinary
or otho-phosphoric acid.
Na
Na
HPO4 H PO + 2H2O Na › PO4 + 12H²O
H
H
Phosphoric
acid.
H
Monosodium
II
Disodium phosphate.
Na
NaPO4 + 12H20
Na
phosphate.
Trisodium phosphate.
Monosodium phosphate is acid, the disodium is neutral, and
the trisodium has an alkaline reaction. Disodium phosphate, or,
as it is frequently called, common or neutral phosphate of soda,
is the most important. It is prepared by neutralizing the cal-
cium acid phosphate, obtained by digesting bone-dust with dilute
sulphuric acid and filtering, with sodium carbonate. Tricalcium
phosphate is precipitated, and disodium phosphate remains in
solution. By evaporation of the filtered liquid, the salt may
be obtained in voluminous, transparent, oblique rhombic prisms,
containing 12 molecules of water of crystallization.
SODIUM BORATE, OR BORAX.
Na2B0407
This salt corresponds to a boric acid containing 2B0203 +
H❜O H2Bo¹O". It results from the action of one molecule
of sodium oxide upon two molecules of boric oxide.
2(Bo20³)+ Na2O= Na Bo¹07
It crystallizes with either 10 or 5 molecules of water.
Borax was formerly obtained from Asia, where it exists in
solution in the waters of certain lakes. By the evaporation
LITHIUM.
299
of these waters a product known as tinkal was obtained; this
is natural borax; it crystallizes in oblique rhombic prisms.
Borax is found in abundance in certain lakes in California.
A great part of the borax of commerce is obtained by satu-
rating the boric acid of Tuscany with sodium carbonate, and
causing the solution to crystallize below 56°. If the boiling
solution be very concentrated, it deposits between 79 and 56°
crystals which are octahedral and contain only 5 molecules
of water of crystallization. The two varieties of borax, the
prismatic and the octahedral, differ then in their proportions
of water of crystallization.
When borax is heated, it melts in its own water, swells up
and becomes dry, and then undergoes igneous fusion. Melted
borax dissolves a great number of oxides and forms with them
variously-colored glasses on cooling. It dissolves in 12 parts
of cold and 2 parts of boiling water; the solution has a faint
alkaline reaction.
Characters of Sodium Salts.-Sodium salts are not pre-
cipitated from their solutions by either hydrogen sulphide,
ammonium sulphide, sodium carbonate, or platinic chloride.
Hydrofluosilicic acid forms with them a white precipitate. A
solution of potassium antimonate produces a white precipitate
of sodium antimonate (Fremy).
Sodium salts impart a yellow color to flames.
A small quantity of alcohol may be ignited in a saucer and
will burn with an almost colorless flame, but the introduction
of a small quantity of sodium hydrate, chloride, or any other
sodium compound, at once colors the flame bright yellow.
This character is very sensitive, and the smallest trace of
sodium may thus be recognized by introducing a platinum wire,
dipped into the substance to be tested, into the colorless flame
of the blow-pipe or of a Bunsen burner.
LITHIUM,
Li 7
In 1817, Arfvedson, a Swedish chemist, discovered a new
alkali, lithia, which is the hydrate of lithium, LiOH, analogous
to potassium hydrate, KOH. To this hydrate corresponds an
oxide, Li'O, and a chloride, LiCl. Bunsen was the first to ob-
tain the metal lithium, which he prepared by electrolysis of the
300
ELEMENTS OF MODERN CHEMISTRY.
fused chloride. It is a silvery-white metal, but its surface rap-
idly tarnishes in the air. It is the lightest of the solid ele-
ments, its density being between 0.578 and 0.589. It melts at
180°. It is less oxidizable than either sodium or potassium.
When heated above its point of fusion in the air or in oxygen,
it burns with a brilliant white flame. It decomposes water at
ordinary temperatures, but without melting like sodium.
The salts of lithium are soluble in water, but the carbonate
and phosphate only slightly so.
There exists also a double
phosphate of sodium and lithium, which is but slightly soluble.
The salts of lithium communicate a red color to the flame of
alcohol or of the Bunsen burner.
The compounds of lithium are generally prepared from the
native silicate known as lepidolite.
CÆSIUM AND RUBIDIUM.
SPECTRUM ANALYSIS.
Cæsium and rubidium are two alkaline metals discovered
by Kirchhoff and Bunsen in 1860-61, by the aid of a new
method of analysis. This method consists in the examination
of spectra; hence the name spectrum analysis.
The solar spectrum formed upon a screen which intercepts a
beam of solar light refracted by passage through a prism, con-
sists of a series of colored bands. The different simple rays
of which white light is composed are unequally refracted by
the prism, and separate from each other on their emergence.
The violet rays, which are farthest turned from their primitive
direction, form the most deviated extremity of the spectrum.
The red rays, which are the least refracted, form the least de-
viated extremity. The visible spectrum of solar light presents.
not only a succession of variously-colored bands; when it is
closely examined by the aid of magnifying instruments, it is
found that the succession is not continuous, but that the lumi-
nous bands are traversed by dark lines. These lines, which
were discovered by Wollaston and studied by Fraunhofer, are
very numerous, and are irregularly distributed throughout the
spectrum, from the red to the violet, but each one of them
occupies a definite position, and for the principal lines that
position has been determined by exact measurements. Fraun-
CÆSIUM AND RUBIDIUM.
301
hofer designated them by the letters A, B, C, D, E, F, G, H.
The D line is the most distinct of all its place is in the yel-
low. Other lights, the stars, for example, give similar discon-
tinuous spectra. On the contrary, an incandescent platinum.
wire, or any other luminous source which contains no volatile
matter, gives a continuous spectrum.
Very interesting facts are observed when the sources of light
are flames into which the vapors of volatile substances, par-
ticularly the metallic salts, are introduced. The spectra of such
flames are formed exclusively of brilliant lines (see plate).
If a platinum wire which has been dipped into a solution
of sodium chloride be introduced into the colorless flame of
a Bunsen burner, the flame will assume a yellow color, and will
give a visible spectrum, but one which is very incomplete,
since it consists of a single yellow line. It has been found
that this line exactly coincides with the dark line D, existing in
the yellow of the solar spectrum. This line characterizes
sodium in all of its compounds: it is the spectrum of sodium.
In the same manner, a flame into which a compound of potas-
sium, lithium, barium, calcium, or other volatile metal is intro-
duced, will give for each metal a particular spectrum formed of
variously-colored lines. Each is perfectly characterized by the
number, color, and position of the lines. Barium gives the most
numerous and the widest lines; other metals give more compli-
cated spectra.
That of iron is composed of 70 brilliant lines.
Kirchhoff and Bunsen, who discovered these facts, made a
happy application of them to analysis. To detect the presence
of a metal in a compound or even in a mixture, a small portion
of the substance is introduced into a colorless gas flame, and
the spectrum then given by the flame is observed by the aid of
an instrument called a spectroscope.
3,000.00 0
The method is so sensitive that
1 of a milligramme
of sodium chloride will render the yellow sodium line distinctly
visible. The discovery of two new metals, cæsium and rubi-
dium, crowned the brilliant researches of Kirchhoff and Bunsen.
Since then, three other new metals have been discovered by
the aid of spectrum analysis: thallium, which gives a green
line, indium, which gives an indigo-blue line, and gallium,
which gives two violet lines very close together. Thallium was
discovered by Crookes and Lamy, indium by Reich and Richter,
and gallium, the discovery of which was most remarkable of
all, by Lecoq de Boisbaudran.
26
302
ELEMENTS OF MODERN CHEMISTRY.
THALLIUM.
The beautiful green line given by this metal was first ob-
served by William Crookes, who regarded it as characteristic
of a new element. The honor of having isolated the latter
and establishing its true character belongs to Lamy.
Thallium is a heavy metal which resembles lead in certain
of its properties. It melts at 200°; its density is 11.9. It
forms an oxide, TIO; a crystallizable hydrate, TIOH, which
is soluble in water and also caustic; a monochloride, TICI, and
a moniodide, TII. These compounds relate it to the alkaline
metals, but others, which include an oxide, Tl2O3, and a trichlo-
ride, TICI³, separate it from that class, Its principal com-
pounds have been studied by Lamy and Willm.
BARIUM
Ba 137
Bunsen obtained barium by the electrolysis of fused barium
chloride; this metal is very avid of oxygen, and tarnishes
rapidly. It decomposes cold water.
Barium Oxide, or Baryta, BaO.-Barium oxide is obtained
by calcining barium nitrate. Its nature was first recognized
in 1808, by Davy, who decomposed it by the voltaic current.
It is a gray, porous substance, which unites energetically with
water, producing a hissing noise and a great disengagement of
steam, due to the elevation of temperature. The product of
the reaction is a white hydrate, ordinarily known as caustic
baryta.
BaO + HO
+
Barium oxide.
Ba(OH)2
Barium hydrate.
Barium hydrate is soluble in two parts of boiling water, and
on cooling is in great part deposited in large tabular crystals,
containing 8 molecules of water. The solution of barium hy-
drate in water is called baryta water.
Barium Dioxide, BaO2.-When dry oxygen is passed over
barium oxide heated to dull redness, the gas is absorbed and a
dioxide, BaO², is formed. It is a gray, porous mass, some-
times greenish. It loses one atom of oxygen at a bright-red
heat. When brought in contact with water, it combines with
BARIUM SALTS.
303
the latter quietly and without disengagement of heat, forming
a pulverulent hydrate.
When treated with sulphuric acid, barium dioxide disen-
gages oxygen mixed with ozone. When its hydrate is intro-
duced into hydrochloric acid, hydrogen dioxide is formed.
Barium Sulphide, BaS.-This is obtained by reducing
barium sulphate with charcoal.
BaSO¹ + C+
Barium sulphate.
BaS + 400
Barium sulphide.
The sulphate is reduced to fine powder, and is mixed with a
certain quantity of flour or rosin. The mixture is then made
into a paste with linseed oil, and shaped into little balls. These
are calcined at a bright-red heat in a covered crucible, and a
porous, gray mass is thus obtained which, when treated with
boiling water, yields a solution which deposits hexagonal tables
after filtration and cooling. These crystals do not present a
very constant composition: it is a mixture of sulphide, sulphy-
drate, and hydrate of barium. Their solution has a light-yel-
low color.
BARIUM SALTS.
Barium Chloride, BaCl2 + 2H2O.-This salt is obtained
by saturating the solution of barium sulphide with hydrochloric
acid. Hydrogen sulphide is disengaged; the solution is boiled,
filtered, and evaporated to crystallization. Barium chloride.
separates in quadrangular tables belonging to the type of the
right rhombic prism. These crystals are inalterable in the air.
100 parts of water at 18° dissolve 43.5 parts of barium chlo-
ride, and 78 parts at 105.5°, the temperature of ebullition of
the saturated solution (Gay-Lussac). Absolute alcohol dis-
solves of its weight of barium chloride.
40
Barium Nitrate, Ba(NO3)2.—Barium nitrate is prepared
by decomposing barium sulphide or carbonate with dilute nitric
acid, and filtering and evaporating the solution.
One
It crystallizes in regular octahedra, or in cubo-octahedra.
The crystals are transparent and unaltered in the air.
part of this salt requires for its solution 20 parts of water at
0.12°; 5 parts of water at 15°; 2.8 parts at 106°, the tem-
perature of ebullition (Gay-Lussac). When heated to redness,
barium nitrate gives off oxygen, nitrogen, and red vapors,
leaving a residue of oxide, BaO.
304
ELEMENTS OF MODERN CHEMISTRY.
Barium Sulphate, BaSO*.-This salt is found abundantly
in nature as heavy spar, and sometimes occurs in right rhom-
bic crystals. It is entirely insoluble in water and acids, with
the exception of concentrated sulphuric acid. It is precipi-
tated as a finely-divided, amorphous powder when sulphuric
acid or a soluble sulphate is added to a solution, even very di-
lute, of a salt of barium.
Barium Carbonate, BaCO³.-Barium carbonate constitutes
an amorphous, white powder, which is obtained by double de-
composition on adding solution of sodium carbonate to a solu-
tion of barium sulphide. Natural barium carbonate is an
abundant mineral, and is found crystallized in right rhombic
prisms; it is called witherite.
Characters of Barium Salts.-Barium salts are precipi-
tated neither by hydrogen sulphide nor by ammonium sulphide.
Sodium carbonate produces in them a white precipitate. Even
when very dilute, the barium salts produce a white precipitate
with sulphuric acid, which is insoluble in either cold or boiling
nitric acid.
STRONTIUM.
Sr 87.5
The compounds of this metal present great analogies to those
of barium.
Strontium was discovered by Davy in 1808, but the metal
was isolated by Bunsen and Matthiessen by the aid of a process
similar to that which serves for the preparation of barium.
Matthiessen describes it as a yellow metal, having a density of
2.50-2.58, harder than lead, and decomposing cold water.
Strontium forms two oxides, a monoxide, SrO, and a dioxide,
SrO2.
Strontium chloride, SrCl, crystallizes in deliquescent needles
which contain three molecules of water of crystallization. It
is very soluble in water and slightly soluble in alcohol; the
alcoholic solution burns with a red flame.
Strontium nitrate, Sr(NO³)², which is prepared like barium
nitrate, is deposited from its hot aqueous solution in anhydrous.
octahedra, and crystallizes at low temperatures in oblique rhom-
bic tables containing 5 molecules of water of crystallization
(Laurent).
The carbonate of strontium, SrCO³ (strontianite), and the
CALCIUM.
305
sulphate, SrSO (celestine), are found native. These two salts
are insoluble in water, and are deposited as white precipitates
on adding a soluble carbonate or sulphate to the solution of a
strontium salt. Strontium sulphate is less insoluble, however,
than barium sulphate.
CALCIUM.
Ca 40
Lime, which is universally known, is the oxide of a metal
called calcium. According to Liès-Bodard and Jobin, calcium
may be obtained by decomposing calcium iodide with sodium
in an iron crucible. Matthiessen obtained it by decomposing
fused calcium chloride by the voltaic current.
Calcium has a yellow color when freshly filed, but it tarnishes
rapidly in moist air and becomes covered with a grayish layer
of hydrate. When heated upon platinum-foil, it takes fire and
burns with a dazzling flame. It decomposes water at ordinary
temperatures.
OXIDE AND HYDRATE OF CALCIUM.
Lime, or calcium oxide, CaO, is obtained by calcining the
carbonate in peculiar furnaces, which are called lime-kilns. It
occurs as large, compact, and hard grayish masses, which con-
stitute quick-lime.
It is infusible, even at the highest temperatures. When
exposed to the air, it attracts moisture and carbonic acid, aug-
ments in volume, and is finally converted into a white powder,
a mixture of calcium hydrate and carbonate. When lime is
sprinkled with water, it absorbs the liquid without giving rise
to any particular phenomenon; but in a little while, the pieces
saturated with water become hot, give off steam, and then they
split and increase in volume. If enough water be used, the
quick-lime will be converted into a white powder, which is
called slaked lime; it is calcium hydrate.
2
CaO + HO = CaOH? Ca(OH)2
When slaked lime is suspended in water, a white, creamy
liquid is obtained that is called milk of lime. If this be fil-
tered or allowed to settle, the clear, limpid liquid resulting will
have an alkaline reaction, for it contains a small quantity of
26*
306
ELEMENTS OF MODERN CHEMISTRY.
calcium hydrate in solution: it is lime-water. Calcium hydrate
is more soluble in cold than in hot water.
Employment of Lime in Constructions.-Lime is largely
employed for building purposes in both ordinary and submarine
constructions. The limestone which is used for the preparation
of lime is rarely pure, and consequently the product of its cal-
cination presents different qualities, according to the propor-
tions of foreign matters which remain in the lime, and which
consist of a small quantity of magnesia, oxide of iron, and
especially clay. Fut limes are those produced by the calcina-
tion of almost pure limestones; they develop much heat, and
swell up very much on slaking. Such lime forms an unctuous
and binding paste with water, and forms ordinary mortar when
mixed with sand. Impure limestones yield lean lime, contain-
ing magnesia, oxide of iron, and clay. It is gray, and develops
but little heat and increases but slightly in volume on slaking.
The calcination of limestone containing from 10 to 30 per cent.
of clay produces hydraulic lime. Such lime sets under water,
that is, the mortar solidifies after a few days, and becomes very
hard, even when immersed in water. On account of this curious
property it is used in submarine constructions. Such lime is
yellow; slaking it produces but little heat, and scarcely any in-
crease in volume. The hydraulic mortar formed by its mix-
ture with sand will harden under water. Mortars possessing
this property may also be prepared by mixing lime with baked
argillaceous materials, such as powdered tiles, pottery, bricks,
etc. Certain argillaceous rocks of volcanic origin, the pozzolana
so abundant near Vesuvius, for example, yield an excellent.
hydraulic lime when mixed with fat lime.
Cement is a variety of lime resulting from the calcination of
limestones containing from 40 to 50 per cent. of slate. When
mixed with water, such cement sets in a few minutes in a solid
mass like plaster. Vicat has shown that the different varieties
of hydraulic lime and cement can be prepared by properly
calcining carbonate of lime, or chalk, with various proportions
of clay. According to him, ordinary mortar sets because the
lime gradually absorbs carbonic acid gas from the air, forming
'a carbonate which hardens and binds together the grains of
sand. The hardening of hydraulic lime and mortar is due to
another cause the clay which they contain in the anhydrous
state tends to become hydrated and to form a double silicate of
calcium and aluminium, or a silicate and aluminate of calcium,
CALCIUM CHLORIDE-CALCIUM NITRATE.
307
insoluble compounds, which become very coherent on contact
with water.
CALCIUM CHLORIDE.
CaCl2
This salt is prepared by dissolving white marble or chalk in
hydrochloric acid. When the solution is concentrated it deposits
large, six-sided prisms, containing 6 molecules of water of crys-
tallization. They are very deliquescent and produce a depres-
sion of temperature when they are dissolved in water.
If they
be mixed with their own weight of snow or powdered ice, a
cold of -45° may be produced.
When they are heated, they melt in their water of crystalliza-
tion, of which they lose 4 molecules at 200°, and the remainder
at a red heat; at the latter point the mass enters into igneous
fusion. On cooling, the fused calcium chloride solidifies to a
white, crystalline mass, in which form it is ordinarily employed
for the desiccation of gases.
Calcium chloride dissolves readily in alcohol.
CALCIUM NITRATE.
Ca(NO3)2+4H2O
This salt is formed naturally in the neighborhood of dwell-
ings, in the soils of cellars, and in damp walls. It is contained
in what are known as saltpetre materials; it exists in certain
spring and well waters. It may be made by saturating nitric
acid with calcium carbonate. It is very soluble in water and
in alcohol. It crystallizes with difficulty in six-sided, oblique
rhombic prisms, which contain 4 molecules of water of crys-
tallization: they are deliquescent.
CALCIUM CARBONATE.
(CARBONATE OF LIME.)
CaCO3
Calcium carbonate is found in great abundance in nature,
and under different forms. It exists crystallized as Iceland
spar and aragonite; the former crystallizes in colorless, trans-
parent, and doubly refracting rhombohedra; the latter in right
rectangular prisms.
308
ELEMENTS OF MODERN CHEMISTRY.
Marble, the various limestones, and chalk, constitute other
varieties of natural calcium carbonate. Pure water dissolves
but feeble traces of this salt; water charged with carbonic
acid dissolves a larger quantity, converting it into dicarbonate.
It is in this state that it is contained in hard waters.
Calcium carbonate may be prepared by double decomposition
between solutions of sodium carbonate and calcium chloride.
When heated to bright redness, it is completely decomposed
into lime and carbonic anhydride.
CALCIUM SULPHATE.
CuSO4
This salt exists in two states in nature: anhydrous, it con-
stitutes the anhydrite of mineralogists; combined with two
molecules of water of crystallization, it forms gypsum or plas-
ter stone. Gypsum sometimes occurs in lance-head-shaped
crystals, grouped together; they are divisible into thin, trans-
parent layers, easily scratched by the finger-nail. Certain
varieties of gypsum constitute alabaster. All the forms of
hydrated calcium sulphate contain 21 per cent. of water.
When heated to 80° in the air, or to 115° in closed vessels,
the sulphate, CaSO¹ + 2H²O, abandons its water of crystalli-
zation and is converted into the anhydrous sulphate. Between
120 and 130°, this dehydration is rapid and complete. It is
operated on the large scale in plaster furnaces. In this state
calcium sulphate will readily recombine with its water of
crystallization. If the plaster be calcined at too high a tem-
perature it will not again become hydrated.
If powdered plaster of Paris be mixed with enough water
to form a creamy liquid, it may be poured into a mould, and
in a few minutes will harden to a compact mass, completely
filling every cavity of the mould. In becoming hydrated, the
particles of calcium sulphate assume the crystalline form and
increase in volume. These properties render plaster of Paris
valuable in building operations.
1000
It is also employed to a large extent in agriculture.
Calcium sulphate is but slightly soluble in water.
parts of boiling water dissolve a little more than 2 parts of
the salt; at 35° they dissolve 2.64 parts; at 20°, 2.05 parts.
CALCIUM HYPOCHLORITE.
309
CALCIUM HYPOCHLORITE.
Ca(CIO)2
Calcium hypochlorite exists in a product largely employed
in the arts under the name of chloride of lime, and which is
obtained by exposing well-hydrated lime to the action of chlo-
rine; it is a mixture of calcium chloride and calcium hypo-
chlorite.
4Cl + 2CaO
CaCl2 + Ca(ClO)²
Calcium chloride. Calcium hypochlorite.
The operation is conducted by passing a current of chlorine
over slaked lime placed in thin layers upon shelves arranged
in the walls of masonry chambers. The chlorine is made in
earthenware vessels, A (Fig. 101), heated in a water-bath; it

ས
GNETSMANGLERS
A
&
D
FIG. 101.
is washed in the jars D, and then conducted into the upper
part of the chamber by the tube G. In order to insure the
preservation of the chloride of lime, an excess of lime is always
left in it.
310
ELEMENTS OF MODERN CHEMISTRY.
Chloride of lime is a powerful bleaching agent; it owes this
property to the calcium hypochlorite which it contains, and
which is decomposed by the action of acids.
If hydrochloric acid be added to a solution of chloride of
lime, chlorine gas is at once disengaged with effervescence.
The reaction may be conceived to take place in two phases.
The hydrochloric acid acts upon the hypochlorite, forming
hypochlorous acid.
2
2HCI + Ca(CIO)²
CaCl2 +
2HCIO
Calcium hypochlorite. Calcium chloride. Hypochlorous acid.
The hypochlorous acid thus set free then reacts with the
calcium chloride, forming calcium hydrate and chlorine.
CaCl2 + 2HC10 Ca(OH)2 + 2012
The calcium hydrate is in the presence of an excess of hy-
drochloric acid, by which it is reconverted into calcium chlo-
ride. The latter salt is thus continually decomposed and
re-formed.
Chloride of lime is also decomposed by less energetic acids,
even by carbonic acid gas.
When a solution of chloride of lime is boiled, the hypochlo-
rite which it contains is converted into chlorate and chloride.
3 Ca(CIO)²
Ca(ClO3)2 + 2CaCl2
Calcium hypochlorite. Calcium chlorate.
pre-
Characters of Calcium Salts.-Calcium salts are not pre-
cipitated either by hydrogen sulphide or ammonium sulphide.
Sodium carbonate forms in them a white gelatinous precipitate.
Sulphuric acid and the soluble sulphates produce a white
cipitate, if the calcium solutions be concentrated or only mod-
erately dilute. Oxalic acid, or better, ammonium oxalate,
produces a white precipitate of calcium oxalate, even in the
most dilute solutions of calcium salts.
MAGNESIUM.
Mg
28
Magnesium was discovered by Bussy. Matthiessen obtained.
it by decomposing fused magnesium chloride by electricity.
Preparation.-Deville and Caron recommend the following
process for the preparation of considerable quantities of mag-
MAGNESIUM OXIDE-MAGNESIUM CHLORIDE. 311
nesium. A mixture of 600 grammes of anhydrous magnesium
chloride, 100 grammes of sodium chloride, 100 grammes of
calcium fluoride, and 100 grammes of sodium cut into small
pieces is heated to redness in a covered crucible. The magne-
sium chloride is reduced by the sodium, and the magnesium
set free collects in little globules disseminated in the fused
mass, which must be stirred with an iron rod. These little
globules are removed from the scoria when cold, introduced
into a charcoal boat, and heated to bright redness in a current
of hydrogen. The magnesium volatilizes and condenses far-
ther on in the tube; it may then be fused with a flux consisting
of magnesium chloride, sodium chloride, and calcium fluoride.
The metal collects at the bottom of the crucible.
Properties.-Magnesium has a density of 1.74 or 1.75. It
fuses at 500°. It decomposes water at ordinary temperatures.
but slowly. It may readily be rolled into ribbon or drawn into
wire. The wire is grayish and not very brilliant. The end
of a bundle of these wires may be heated in an alcohol lamp
until they take fire, and the whole may then be plunged into a
jar of oxygen. They burn with an incomparable splendor that
the eye cannot support; at the same time the jar becomes filled
with a white smoke, which condenses into a white powder, the
product of the combustion; it is magnesia, the oxide of mag-
nesium.
MAGNESIUM OXIDE, OR MAGNESIA.
MgO
This body is obtained by calcining white magnesia, or mag-
nesium hydrocarbonate. It is a white, infusible, light, and
insipid powder. It does not dissolve in water, but combines
with that liquid forming a hydrate, Mg(OH)2 MgO.H³0.
This hydrate slowly restores the blue color to reddened litmus-
paper.
Magnesium hydrate is precipitated when a solution of caustic
potassa is added to the solution of a magnesium salt.
Calcined magnesia is frequently employed in medicine.
MAGNESIUM CHLORIDE.
MgCl2
This salt is known in the anhydrous state and crystallized.
Anhydrous magnesium chloride is prepared by dissolving the
312
ELEMENTS OF MODERN CHEMISTRY.
carbonate in hydrochloric acid, adding ammonium chloride to
the solution and evaporating to dryness. A double chloride of
magnesium and ammonium is thus obtained which may be per-
fectly dried; the dry mass is introduced into a clay crucible and
heated; the ammonium chloride volatilizes, while the magne-
sium chloride remains, and solidifies on cooling to a colorless,
pearly mass.
It is very soluble in water, and when properly concentrated,
the solution deposits deliquescent, prismatic crystals containing
six molecules of water of crystallization. These crystals can-
not be dehydrated, nor can their solution be evaporated to
dryness, without decomposing the chloride by the action of the
water; under these circumstances the magnesium chloride is
converted into hydrochloric acid and magnesia.
MgCl2 + H2O = 2HCl + MgO
MAGNESIUM CARBONATE.
MgCO3
The anhydrous carbonate MgCO3 (giobertite, magnesite) is
found native, crystallized in rhombohedra, similar to those of
calcium carbonate. Considerable deposits are also found of a
double carbonate of magnesium and calcium, known as dolomite.
When a boiling solution of magnesium sulphate is precipi-
tated by an excess of sodium carbonate, carbonic acid gas is
disengaged, and a precipitate is formed containing at the same.
time magnesium carbonate and magnesium hydrate (magnesium
hydrocarbonate).
When this is dried, it constitutes the white magnesia of the
pharmacies.
MAGNESIUM SULPHATE.
MgSO4 + 7H2O
This salt exists in solution in sea-water and in certain purga-
tive mineral waters, such as those of Sedlitz, in Bohemia, and
Epsom, in England. Hence the names Sedlitz salt and Epsom
salt, formerly given to this body.
At Stassfurth, it is found crystallized with one molecule of
water (kieserite) and mixed with the anhydrous sulphate.
It is deposited from the mother-liquors of salt-marshes when
they are evaporated at the natural summer heat (Balard).
When it separates at ordinary temperatures from an aqueous
ALUMINIUM.
313
solution that has been tolerably concentrated by heat, it crystal-
lizes in transparent and colorless right rhombic prisms. At
0°, it crystallizes with 12 molecules of water; at 30°, with 6
molecules.
Its taste is disagreeable, at the same time salty and bitter.
When magnesium sulphate crystallized with 7 molecules of
water is heated, it first melts in its water of crystallization, of
which it loses 6 molecules. At 1322, it still retains one mole-
cule, which it loses only at 210°.
It is very soluble in water; 100 parts of water at 0° dis-
solve 25.76 parts of the anhydrous sulphate, and 0.47816
part for every additional degree (Gay-Lussac).
Magnesium sulphate forms a double sulphate with potassium
sulphate, K2SO¹.MgSO¹ + 6H2O.
Characters of Magnesium Salts. They are precipitated
by neither hydrogen sulphide nor ammonium sulphide. Sodium
carbonate produces a white, flocculent precipitate. Potassium
hydrate and ammonia form white precipitates, but ammonia
will not precipitate magnesia from an acid solution or from one
containing ammonium chloride. Sodium phosphate and ammonia
together produce a granular precipitate of ammonio-magnesium
phosphate.
ALUMINIUM.
Al 27 5
This metal long remained a chemical curiosity, and has only
become common within a few years. It was discovered in
1827 by Wöhler, and in 1854, H. Saint-Claire Deville succeeded
in producing it on the large scale. It is obtained by decom-
posing aluminium and sodium double chloride by sodium.
Al²C16,2NaCl + 3Na 8NaCl + Al²
In the arts, a mixture of sodium, aluminium and sodium
double chloride, and cryolite, is projected into a reverberatory
furnace heated to bright redness. The cryolite acts as a flux:
it is a double fluoride of sodium and aluminium, found native
in Greenland.
Aluminium is a white metal, and has a somewhat bluish
lustre when polished. It is ductile, malleable, very sonorous,
and a good conductor of heat and electricity. It is as light as
glass and porcelain, its density being only 2.56,
O
27
314
ELEMENTS OF MODERN CHEMISTRY,
Aluminium is unaltered by the air, even by moist air. When
heated in thin sheets in a current of oxygen, it burns and is
converted into alumina. Nitric and sulphuric acids scarcely
attack it. Hydrochloric acid dissolves it rapidly, disengaging
hydrogen. It is immediately attacked by boiling solutions of
potassium or sodium hydrates; hydrogen is disengaged and
alkaline aluminates are formed.
ALUMINIUM OXIDE, OR ALUMINA.
A1203
Corundum, a very hard precious stone, consists of anhydrous
alumina. It is named orientul ruby when it has a red color;
sapphire when it is blue, and oriental topaz when it has a
yellow tint. Emery is a sort of opaque corundum; it is gran-
ular and colored by a small quantity of oxide of iron.
When ammonium carbonate is added to a solution of alum,
carbon dioxide is evolved, and a gelatinous precipitate of hy-
drated alumina is formed.
The precipitate dissolves readily in caustic potassa. When
heated, it loses water and is converted into anhydrous alumina ;
the latter is undecomposable by heat; it fuses only in the flame
of the oxyhydrogen blow-pipe. Gaudin has succeeded in pro-
ducing fine precious stones that cannot be cut by the file, and
at least as hard as rock-crystal, by melting Limoge emerald
(anhydrous alumina) with various substances, such as sand,
kaolin, talc, and lime, which are added as fluxes.
Alumina cannot be reduced by charcoal at the highest tem-
peratures; it can only be reduced by the joint action of char-
coal and chlorine; aluminium chloride is then formed.
ALUMINIUM CHLORIDE.
A12C16
When a current of chlorine is passed over an incandescent
mixture of alumina and charcoal, aluminium chloride and
carbon monoxide are formed (Oersted).
Al²0³ + 3C + C1º = 3CO + Al²C16
Aluminium chloride thus formed is a white, crystalline sub-
stance, sometimes having a light-yellow color. It is fusible, and
ALUMINIUM SULPHATE-ALUM.
315
volatilizes in the air at a temperature little above 100°. When
exposed to the air it gives off white fumes and attracts moist-
It dissolves in water with production of heat.
ure.
A solution of aluminium chloride may be obtained by dis-
solving gelatinous alumina in hydrochloric acid. When this
solution is evaporated, it decomposes as soon as it attains a
certain degree of concentration, disengaging hydrochloric acid,
and leaving alumina.
Aluminium chloride readily combines with sodium chloride,
forming a double chloride, Al C16.2NaCl, fusible towards 200°.
ALUMINIUM SULPHATE.
Al²(SO4)3 + 18H²0
This is obtained in the arts by decomposing non-ferruginous
clays with sulphuric acid. It crystallizes with difficulty in
needles and in thin, pearly scales. In this state it contains 18
molecules of water of crystallization. It dissolves in 2 parts
of cold water. When heated, it first loses its water, and at a
higher temperature it gives off sulphuric anhydride, leaving a
residue of alumina.
Al2(SO4)3SO³ + Al2O3
It is seen that aluminium sulphate represents 3 molecules
of sulphuric acid, in which the 6 atoms of hydrogen have been
replaced by the hexatomic couple Al².
H2SO¹
SO⭑
{
SO+
H2SO¹ + AFO³ 3H³O + (Al²) SO
H2SO¹
ALUMINIUM AND POTASSIUM DOUBLE SUL-
PHATE, OR ALUM.
Al2(SO4)³. K2SO4 + 24H²O
If a concentrated solution of aluminium sulphate be added
to a concentrated solution of potassium sulphate, and the mix-
ture be stirred with a glass rod, a crystalline deposit soon forms
from the union of the two salts to form a double sulphate
which is alum.
This salt is not very soluble in cold water, but dissolves
abundantly in boiling water, and is deposited on cooling in
316
ELEMENTS OF MODERN CHEMISTRY.
voluminous, transparent octahedra. When heated, these crys-
tals melt in their water of crystallization (24 molecules), and
in losing this water, the melted mass swells up considerably.
Alum may be obtained crystallized in cubes, and it is prepared
in this form in the neighborhood of Civita-Vecchia by working
a mineral which contains the elements of alum with a large
excess of alumina. The mineral is known as aluminite, and the
cubical alum is called Roman alum.
This cubical variety may be prepared in the laboratory by
adding a small quantity of potassium carbonate to a hot solu-
tion of ordinary alum, so that the precipitate first formed will
be redissolved on agitating the liquid. On cooling, cubical
crystals are deposited which are ordinarily opaque. These are
formed under the influence of a small quantity of basic sul-
phate (aluminium sulphate combined with an excess of alu-
mina) contained in the liquid, and which probably enters into
the constitution of the crystals. With this slight difference,
octahedral alum and cubical alum present the same composi-
tion, which is expressed by the formula Al(SO)³.K²SO¹ +
24H2O.
Ammonia alum is obtained by adding ammonium sulphate
to solution of aluminium sulphate. It possesses a constitution
analogous to that of ordinary alum, with which it is isomor-
phous. It contains
3
Al²(SO¹³.(NH4)2SO4 + 24H2O
It is often substituted in the arts for potassium alum, being
cheaper than the latter.
When strongly calcined, it leaves a residue of pure alumina.
Other alums are known in which iron, manganese, and chro-
mium play the part taken by aluminium in ordinary alum.
These alums are all isomorphous (Mitscherlich). By the ac-
tion of sulphuric acid on the sesquioxides of the above metals,
sulphates are formed analogous to aluminium sulphate, and of
which the composition is expressed by the general formula
(R²)i(SO¹)³. With the sulphates M²SÕ¹, they form alums, all
of which crystallize in regular octahedra, and which can be
mixed in one and the same crystal without the form of the
latter being affected by the mixture.
The following are the most important of these compounds:
Manganese alum
•
Iron alum
Chromium alum
•
Mn²(SO4)3. K2SO4 + 24H²0
Fe2(SO4)3.K2SO4 + 24H2O
Cr²(SO4)3.K2SO4 + 24H2O
ALUM.
317
It is seen that each of these presents an atomic composition
similar to that of ordinary alum.
The aluminium compounds are widely disseminated in nature.
Feldspar is a double silicate of aluminium and potassium. The
latter metal is replaced by sodium in albite, and by calcium in
labradorite.
Many other minerals contain aluminium silicate combined
with alkaline or earthy silicates: such are granite, idiocrase,
mica, etc. The zeolites are silicates of aluminium containing
water of crystallization.
Clay is a hydrated silicate of aluminium; it results from the
disintegration of feldspar by the action of water and air, the
alkaline silicate being gradually dissolved and eliminated. The
purest clay is kaolin, or porcelain clay; it contains alumina,
silica, and water in the proportions indicated by the formula
2SiO², A¹²O³,2H20.
Plastic clays are those which form a binding paste when
mixed with water, and acquire great hardness after being
baked, without fusing. They are used for the manufacture of
pottery, refractory fire-bricks, and crucibles. Fuller's earth is
a clay which forms with water a paste that is but slightly adhe-
rent; it is employed in scouring and fulling cloth.
Marls are intimate mixtures of clay and chalk; they are
employed in agriculture.
Pottery. Clay is the basis of all pottery. Other matters,
such as sand, powdered feldspar or quartz, etc., are generally
added, for while they diminish the plasticity of the clay, they
also diminish its shrinkage on baking. Pottery is classified as
semivitrified pottery, such as porcelain and stoneware; porous
pottery, such as faïence and bisque; and common pottery or
terra-cotta.
Porcelains.-These are manufactured from kaolin, to which
sand is added to prevent shrinkage, and feldspar, which causes
the ware to undergo a partial fusion, and renders it translucent.
These materials are finely pulverized, mixed with water, and
the paste is kneaded for a long time in order to render it homo-
geneous. Pieces fashioned in this paste are submitted to a pre-
liminary baking, which gives them a certain degree of coherence.
The porous porcelain thus obtained must be coated with a var-
nish which will melt and spread upon its surface: this glaze is
27*
318
ELEMENTS OF MODERN CHEMISTRY.
formed of a mixture of quartz and kaolin reduced to an impal-
pable powder; the latter is suspended in water, into which the
pieces are dipped. They are then subjected to a second baking
in ovens where the temperature is sufficiently elevated to fuse
the glaze and partially vitrify the paste.
Ceramic Stonewares.-These are manufactured from the
same materials as porcelain, but less pure; they are therefore
slightly colored. They are baked at a high temperature, and
are glazed by throwing common salt upon the incandescent
objects in the furnace; hydrochloric acid is disengaged, and a
double silicate of aluminium and sodium is formed, which fuses
and spreads upon the surface of the ware.
Faïences are made from plastic clay mixed with quartz re-
duced to an impalpable powder. Articles formed of this paste
are submitted to a preliminary baking, and are then coated with
a fusible glaze, composed of quartz, potassium carbonate, and
oxide of lead. A second baking causes the pieces to become
covered with an impermeable, vitreous layer of silicate of lead
and potassium. This glaze is transparent; for ordinary ware
it is rendered opaque by the addition of oxide of tin. It is
a true enamel.
Common pottery, which serves for culinary purposes, is made
from ferruginous clay, mixed with sand and marl. The glazing
is composed of a double silicate of aluminium and lead.
IRON.
Fe(Ferrum)
56
Natural State and Metallurgy.-Iron is the most impor-
tant of the metals. Its preparation and working are difficult,
therefore it was not the first metal used by civilized man. The
bronze age preceded the iron age, and those who first employed
the latter metal probably extracted it from the masses which
fall from time to time upon the surface of the earth, and are
known as meteorites. Their principal constituent is metallic
iron, which is alloyed with nickel, cobalt, and chromium.
Iron is employed in three principal forms: soft or malleable
iron, cast iron, and steel. Soft iron is almost pure iron; cast
iron is a combination of iron with carbon and silicon; steel
also contains carbon, but in smaller proportion than cast iron.
The principal ores of iron are the magnetic, or black oxide,
IRON.
319
Fe³O¹, red hematite, Fe2O³, and spathic iron or ferrous carbon-
ate, FeCO³. The various hydrates of the sesquioxide (olitic
iron, brown hematite, etc.) and ferrous carbonate mixed with
clay (bog-iron ore), are more abundant than the preceding, but
are not as rich and are less valuable.
All of these minerals are oxidized. If the ore contain sul-
phur, that element is first driven out by roasting. The metal-
lurgy of iron then consists in reducing the oxide with carbon,
and separating the reduced iron from the earthy matter, which
is generally silicious. Two methods are employed for this
purpose. The first consists in heating the rich ores with
charcoal alone; part of the oxide of iron then combines with
the gangue, forming a very fusible slag (double silicate of
aluminium and iron). This is the Catalan method. The
other consists in mixing the ore with coal and calcium carbon-
ate; the gangue then com-
bines with the lime, forming
a double silicate of lime and
aluminium, which fuses only
at a very high temperature.
Under these conditions the
iron unites with a portion
of the carbon, forming cast
iron. This is the blast-fur-
nace method.
Cutalan Method.-This is
only applicable to very rich
ores and in countries where
combustibles are expensive,
as in Spain, the Pyrenees,
and in Corsica.

EFET
FIG. 102.
SOUNDSER
Fig. 102 represents a sec-
tion of a Catalan furnace; it
is a trough-shaped masonry
furnace with a hearth. The
materials are placed in two
piles, side by side, upon a layer of well-ignited charcoal; one pile
consists of charcoal and is next the tuyère; the other is the
ore, equal to half the quantity of charcoal, and is placed oppo-
site. The combustion is sustained by the blast from a tuyère,
D, which reaches the border of the hearth. The carbon
dioxide here formed is converted into carbon monoxide by the
320
ELEMENTS OF MODERN CHEMISTRY.
mass of incandescent charcoal, and the latter gas reduces the
ore, again passing into the state of dioxide. Metallic iron is
thus formed, and at the same time a portion of the ferric
oxide is reduced to ferrous oxide, and combines with the
gangue, forming a double, alumino-ferrous silicate, which is very
fusible and constitutes the slag. The reduced iron collects in
the bottom of the hearth in the form of a spongy mass, which
is agglutinated and forged under the hammer.

ཡ་ན་ག་ག་ག་ག་ག་ག་ ་ ་
-
•
三
​મ
איוו!!
་་་་་་
མི་མཚན་མི་ ་བ་མ་འ་དངས་
---
FIG. 103.
Blast-furnace Process.-All iron ores may be treated by this
method. They are crushed and introduced with alternate
layers of limestone and coal into the blast-furnace (Fig. 103).
The latter has the form of two cones, the bases of which are
IRON.
321
joined together. It is closed at the bottom, and hot air is in-
jected through tuyères to sustain the combustion. It is open at
the top, where it is continually charged with fresh materials, as
the incandescent mass sinks in the furnace and the molten mate-
rials are drawn off below. The latter first collect in
The latter first collect in a cavity
placed below the vent of the tuyère, and separate on this
hearth into metal, which sinks to the bottom, and slag, which
floats and flows over the edge. When the crucible is full of
molten metal, the latter is run off into channels made in sand
upon the floor of the casting-room. In these rough moulds it
solidifies in bars having a semicircular section, which are called
pigs.
The reactions which take place in the blast-furnace are of
great interest. At the lower part, where the temperature is
the highest, carbon dioxide is produced by the combustion of
the coal; farther up, in the widest portion, this gas is reduced
to carbon monoxide by the incandescent coal; still higher,
where the furnace begins again to contract, and where the
temperature is dull red, the carbon monoxide reduces the oxide
of iron, and a spongy mass of metallic iron is there formed.
In descending, this iron unites with part of the carbon, and
at the same time the silica of the gangue combines with the
lime, forming a silicate which fuses and constitutes the slag.
A small quantity of silica is reduced in the hottest part of
the furnace, and the silicon formed combines with the cast iron.
Cast iron is converted into soft iron by refining; this opera-
tion consists in removing from the cast iron the greater part
of its carbon. For this purpose it is melted in contact with
the air; the carbon, silicon, and a small proportion of iron are
oxidized, forming a basic silicate, of which the excess of oxide
is finally reduced by the carbon of the cast iron. The latter
thus becomes less fusible, and is converted into a spongy mass
of soft iron. Several of these masses are united and the scoria
expressed from them by the blows of a steam-hammer. Or the
metal is melted on the hearth of a reverberatory furnace under
a layer of ferruginous scoriæ and scales of oxide of iron; the
oxygen of these materials burns the carbon out of the cast iron,
the whole mass being vigorously stirred. The latter operation
is called puddling.
Preparation of Pure Iron.-Pure iron may be obtained by
reducing ferric oxide by hydrogen at a temperature near red-
ness, or by passing hydrogen over anhydrous ferrous chloride
0*
322
ELEMENTS OF MODERN CHEMISTRY.
contained in an incandescent porcelain tube. Hydrochloric
acid is formed and evolved, and the iron remains as a gray,
spongy mass, having a metallic lustre where it has been in
contact with the porcelain (Peligot).
Properties of Soft Iron.-Forged, or bar iron, is not chem-
ically pure. It contains a small quantity of carbon, and traces
of silicon, sulphur, and phosphorus, and even nitrogen. The
purest soft iron is that used for the teeth of carding-machines.
and for piano-strings.
The density of forged iron varies from 7.4 to 7.9. It is
very tenacious, ductile, and malleable. When rolled out, it is
called sheet iron. Tin plate is sheet iron covered with a layer
of tin. Galvanized iron is coated with a surface of zinc.
Iron melts only at the highest heats of a wind-furnace.
When softened by a white heat, it may be soldered to itself, or
welded, a very important property for the working of the metal.
Iron is attracted by the magnet; it is magnetic; but it is
not, like steel, capable of retaining magnetism when removed
from the magnetic influence.
It is not altered by dry air at ordinary temperatures, but at
a red heat it absorbs oxygen and is converted into scales of
black oxide of iron.
Iron may be obtained as an impalpable powder by reducing
finely-divided ferric oxide by a current of hydrogen at as low a
temperature as possible. In this state it takes fire when ex-
posed to the air at ordinary temperatures: it is pyrophoric.
Iron rapidly becomes oxidized in moist air; it becomes cov-
ered with a layer of rust, which is ferric hydrate. It is con-
sidered that the oxidation of iron moistened with water is first
set up by the oxygen dissolved in the water; it continues
with greater energy as soon as a light coat of ferric hydrate
has been formed on the metal. The hydrate forms a voltaic
couple with the iron itself, by which the water is decomposed;
part of the hydrogen displaced by the iron combines with the
nitrogen of the air, forming ammonia; indeed, rust always
contains a small proportion of ammonia.
Iron decomposes water at a red heat, setting free the hydro-
gen. It dissolves readily in hydrochloric acid, liberating impure
and fetid hydrogen. Its oxidation by nitric acid is attended
by curious phenomena.
If dilute nitric acid be poured upon iron tacks, the metal is
at once attacked with an abundant disengagement of red vapors.
IRON.
323
On the other hand, the same metal is not attacked by very
concentrated nitric acid (monohydrated), and after having been
exposed to the strong acid, the tacks may be put into dilute acid,
and the latter will then be found to have no effect.
By the action of the concentrated acid, the iron becomes
passive; its surface is covered with a thin layer of gas which
protects it. But if it be touched at any point with a copper
wire while in the dilute acid, chemical action will instantly be
re-established.
Cast Iron and Steel. The properties and appearance of cast
iron differ with the proportions of carbon and silicon which it
contains. The iron does not form definite compounds with
these bodies; they seem to be dissolved by the cast iron when
it is liquid. When cast iron containing much carbon is quickly
cooled, it becomes hard, brittle, whiter than soft iron, and seems
homogeneous. This is white iron. When slowly cooled, a large
proportion of the carbon is deposited as laminæ of graphite,
and the less homogeneous iron then possesses a certain degree
of malleability: it is gray iron.
Some cast irons contain traces of sulphur and phosphorus;
they remain white even after very slow cooling. Others are
lamellar and glittering; they contain manganese and are rich
in carbon.
The proportion of carbon contained in cast iron varies from
2 to 5.5 per cent. Steel contains less carbon, from 0.7 to 2
per cent. The quantities of carbon contained in steel and even
in cast iron render it difficult to suppose that these products
are veritable carbides of iron.
Steel may be obtained by a partial decarbonization of cast
iron. Manganiferous iron is especially applicable for this prep-
aration. It is submitted to a partial refining, being maintained
in the liquid state for some hours under a layer of scoriæ rich
in oxide of iron. A part of the carbon is burned out by the
oxygen of this oxide: natural steel is thus obtained.
Soft iron may be converted into steel. The operation is con-
ducted in cases of refractory fire-clay, into which bars of iron,
and charcoal-powder, mixed with a small quantity of ashes and
common salt, are introduced in alternate layers. The bars being
thus isolated in a bed of charcoal, the cases are closed and
heated to redness in a furnace. The incandescent metal absorbs
carbon, and at the termination of the operation is found con-
verted into steel by cementation.
324
ELEMENTS OF MODERN CHEMISTRY.
The most homogeneous and most valuable steel is cast steel.
It is obtained by fusing crude steel in crucibles in a wind-fur-
nace.
Bessemer has introduced an important improvement in the
manufacture of steel. His process, which bears his name, con-
sists in adding variable quantities of a properly-constituted cast
iron to molten and perfectly refined soft iron.
In this process, the iron to be converted into steel is decar-
bonized by a current of air which is forced through the molten
FIG. 104.
metal by strong press-
ure. The operation is
conducted in an appa-
ratus represented in
Fig. 104, which is
called the converter. It
has an ovoid form, is
constructed of strong
plate iron, and is well-
lined with refractory
fire-bricks. It is ar-
ranged on trunnions, so
that an oscillating move-
ment may be given to it.
The air arrives under
pressure by the tuyères
which open into the bot-
tom of the converter.
The latter is first filled
with incandescent coke,

which is brought into active combustion by the blast. When
the interior of the converter is heated to whiteness, the coke
is emptied out and replaced by the molten cast iron, the con-
verter being inclined to prevent the entrance of the metal into
the tuyères. The blast is then again turned on, and the com-
pressed air bubbling through the molten metal burns out all
of the carbon. A flame of great brilliancy rushes from the
orifice of the apparatus, and the aspect of this flame indicates
precisely the progress of the operation and its termination.
At this moment the apparatus is inclined, the blast arrested,
and a sufficient quantity of melted cast iron or spiegeleisen, a
crystalline cast iron rich in carbon, is added to the now refined
iron to convert the whole into steel; about 7 per cent. of spie-
OXIDES OF IRON.
325
geleisen is required. The steel is then run out into suitable
moulds.
The valuable qualities of steel are well known. It is suscep-
tible of a high polish; it is ductile and malleable like iron, and
can also be forged. At the temperature at which malleable
iron becomes soft, steel melts. It becomes hard and brittle
when it is suddenly cooled after having been heated to redness.
This operation, which is called tempering, develops new quali-
ties in the steel,-elasticity and hardness. It assumes these
properties in different degrees, according to the rapidity of the
cooling, and the difference between the temperature to which
it has been heated and that to which it is cooled. The greater
this difference, and the more rapid the cooling, the harder will
the steel become. After a slow cooling, it is soft and mallea-
ble like iron.
When tempered steel is heated, and allowed to cool slowly,
it partly or entirely loses its hardness. It loses it entirely if
it be heated to the temperature to which it was exposed before
tempering. Its temper is drawn incompletely, that is, it re-
tains a certain amount of hardness and elasticity, if it be re-
heated to inferior temperatures. The qualities which it will
assume after cooling may be predicted from the various tints
developed on its surface during the heating. Each of these
tints corresponds to a determined temperature.
Straw-yellow corresponds to 220°
Brown
Light blue
Indigo-blue
Sea-green
255°
(6
285-290°
((
295°
331°
OXIDES OF IRON.
Three oxides of iron are known:
Ferrous oxide
•
Ferric oxide.
Ferroso-ferric oxide
•
FeO
Fe203
Fe³04
Fremy has also discovered the existence of a ferric acid, of
which the composition is not certainly established.
Ferrous Oxide, FeO.-Debray has obtained this oxide by
partially reducing ferric oxide. The latter is heated in a cur-
rent of gas formed of equal volumes of carbon monoxide and
carbon dioxide. A black powder remains, which is ferrous
oxide.
Fe²0³ + CO
2FeO + CO²
28
326
ELEMENTS OF MODERN CHEMISTRY.
Ferric Oxide, Fe2O³.—This is found anhydrous in nature
in red hematite and specular iron. It may be prepared by
calcining ferrous sulphate, or green vitriol. This salt first
loses its water, and then at a red heat decomposes into sul-
phuric anhydride, sulphurous oxide, and ferric oxide.
2FeSO* SO³ + SO² + Fe²0³
A red powder is thus obtained, which is known as colcothar,
or jeweller's rouge.
This oxide is amorphous, while red hematite is crystallized in
acute rhombohedra. H. Deville has succeeded in converting
the amorphous oxide into the crystallized by heating the former
to redness in a very slow current of hydrochloric acid.
Rust is ferric hydrate, a combination of ferric oxide with
water, and ordinarily presents the composition
2Fe²0³ + 3H2O
Such a hydrate is also encountered in nature as brown
hematite. Another natural hydrate, containing Fe2O3 + H2O,
is known under the name of goethite.
Ammonia or potassium hydrate will at once produce a volu-
minous and flocculent, rust-colored precipitate in a solution of
ferric chloride. This precipitate constitutes a ferric hydrate.
But if an excess of tartaric acid be added to the solution of
a ferric salt, the liquid may be saturated with potassium hy
drate and will still remain clear, no precipitate of ferric hydrate
being formed.
Advantage is taken of this property in analysis for the sepa-
ration of ferric oxide from other oxides which tartaric acid does
not retain in solution in an alkaline liquid.
If a solution of ferric acetate be poured into a dialyser
(page 199), and the water in the exterior vessel be frequently
changed, the salt will finally be entirely decomposed. Acetic
acid will pass through the membrane, while ferric hydrate will
remain dissolved in the water in the dialyser (Graham).
Ferroso-ferric Oxide, Fe³O'.-This compound, also called
magnetic oxide of iron, constitutes the black scales which form
upon the surface of iron when it is heated to redness in the
air; it may be regarded as a compound of ferrous and ferric
oxides. FeO + Fe²0³ = Fe³O¹.
SULPHIDES OF IRON-CHLORIDES OF IRON.
327
SULPHIDES OF IRON.
Several sulphides of iron are known.
The disulphide, or pyrites, FeS2, a largely-diffused mineral,
is the most important of these sulphides. It occurs in two
distinct forms:
Yellow pyrites, which crystallizes in cubes. It occurs as
brilliant cubes, or dodecahedra, having a yellow color and a
metallic lustre.
White pyrites, which forms rhombic prisms, variously modi-
fied, and presents a dull, greenish-yellow color. This variety
is much more alterable than the other, and possesses a great
tendency to attract oxygen from the air and become converted
into sulphate. When heated in closed vessels, pyrites loses a
part of its sulphur.
A combination of monosulphide and sesquisulphide of iron
is encountered in nature; it crystallizes in regular hexagonal
prisms and is called magnetic pyrites.
Monosulphide of Iron, FeS, is found in small quantity in
many meteorites. It is ordinarily obtained by heating to red-
ness in a covered crucible a mixture of three parts of iron-
filings and two parts of sulphur. When the mixture has
fused, it is poured out and solidifies to a brittle, blackish mass,
having a metallic reflection. In this state, it is used for the
preparation of hydrogen sulphide.
CHLORIDES OF IRON.
Ferrous Chloride, FeCl2, is obtained anhydrous by the action
of dry hydrochloric acid gas upon metallic iron. It forms white
pearly scales. When iron is treated with aqueous hydrochloric
acid, it dissolves, and hydrogen is disengaged. The green,
filtered liquid deposits, when sufficiently concentrated, bluish-
green, oblique rhombic prisms. This is hydrated ferrous chlo-
ride, FeCl2 + 4H2O.
Ferric Chloride, Fe²Cl, is formed when a current of chlorine
is passed over iron-turnings heated in a glass or poreclain tube.
The two bodies combine with incandescence, and if the chlorine
be in excess, ferric chloride will be obtained as a brilliant black,
crystalline sublimate.
328
ELEMENTS OF MODERN CHEMISTRY.
This body is very soluble in water and forms a yellow-brown
solution. The latter may be obtained by dissolving ferric oxide,
such as powdered hematite, in hot hydrochloric acid, or by
passing chlorine into a solution of ferrous chloride. Ferric
chloride is also soluble in alcohol.
FERROUS SULPHATE.
FeSO+7H2O
This salt has long been known under the names green
vitriol and copperas. It is obtained by exposing iron pyrites
to the air, or roasting that mineral at a moderate heat. It is
generally prepared by dissolving iron in dilute sulphuric acid,
and it is a residue from the preparation of hydrogen sulphide
by means of iron sulphide and dilute sulphuric acid.
It crystallizes in oblique rhombic prisms, containing 7 mol-
ecules of water of crystallization. When exposed to the air,
these crystals effloresce slightly, and at the same time their
surface becomes yellow from absorption of oxygen and the
formation of ferric subsulphate.
2FeSO¹ +0 Fe²O(SO¹)² Fe2O3.2SO3
When heated, they lose their water, of which six molecules
are disengaged at 114°, and the seventh only at 300°. At a
higher temperature the salt decomposes into sulphurous oxide,
and a ferric subsulphate different from the preceding.
2FeSO SO² + (Fe²O²)SO
The crystals of ferrous sulphate are freely soluble in water.
100 parts of the salt dissolve in 164 parts of water at 10°, and
in 30 parts of boiling water. The green solution absorbs oxy-
gen from the air, becomes troubled, and deposits yellow ferric
subsulphate.
Other hydrates of ferrous sulphate are known. According
to Mitscherlich, a saturated boiling solution of the salt deposits
at 80° crystals containing four molecules of water. According
to Marignac, when a solution of ferrous sulphate containing
free sulphuric acid is evaporated in a vacuum, crystals are first
deposited which contain 7 molecules of water, then a sulphato
FeSO4 + 5H2O, and finally, FeSO4H2O.
The sulphate FeSO¹ + 5H2O, is isomorphous with crystal-
lized cupric sulphate (blue vitriol), and like it crystallizes in
dissymetric prisms.
FERRIC SULPHATE-FERROUS CARBONATE.
329
FERRIC SULPHATE.
Fe2(SO4)3
This salt is obtained by heating ferrous sulphate with nitric
and sulphuric acids; the brown solution is evaporated, and the
residue well dried.
2FeSO+H2SO + 0 = H2O + Fe2(SO4)3
Ferric sulphate is a slightly-yellowish, white mass, which
dissolves completely, but very slowly, in water. The solution
is yellow-brown, and has an acid reaction.
When concentrated by evaporation, it deposits a deliquescent,
yellowish, crystalline mass, which constitutes hydrated ferric
sulphate.
There are several ferric subsulphates; those which have
been mentioned above result from the action of one molecule
of ferric oxide upon one or two molecules of sulphuric acid,
the neutral sulphate resulting from the action of one molecule
of ferric oxide upon three molecules of sulphuric acid.
H'SO+Fe2O3 H2O + (Fe²0²)"SO'
Ferric monosulphate.
H2SO¹
H2SO4
+Fe2O32H2O+ (Fe2O)iv
{
J SO +
SO*
Ferric disulphate.
H2SO¹
SO+
H2SO4 + Fe²0³ 3H2O +
H2SO¹
(Fe²) SO+
SO¹
Ferric trisulphate (normal sulphate).
FERROUS CARBONATE.
FeCO³
Spathic iron ore, which crystallizes in rhombohedra, is fer-
rous carbonate. When a solution of sodium carbonate is added
to a solution of ferrous sulphate, a greenish-white precipitate
is obtained, which rapidly becomes colored in the air, absorb-
ing oxygen and losing carbonic acid. When recently precipi-
tated, it dissolves in a large excess of carbonic acid.
Characters of Ferrous Salts.-The solutions of these salts
are green; they are not precipitated by hydrogen sulphide, but
ammonium sulphide forms a black precipitate of ferrous sul-
28*
330
ELEMENTS OF MODERN CHEMISTRY.
phide. Potassium hydrate or ammonia produces a greenish-
white precipitate of ferrous hydrate, insoluble in an excess of
the reagent, and rapidly becoming colored in the air. Potas-
sium ferrocyanide (yellow prussiate of potash) forms with fer-
rous salts a light-blue precipitate. Potassium ferricyanide (red
prussiate) forms a dark-blue precipitate. Solution of gall-nuts
does not color ferrous salts.
Characters of Ferric Salts.-Hydrogen sulphide produces.
a precipitate of sulphur, reducing the salts to the ferrous state.
Ammonium sulphide precipitates them black. Potassium hy-
drate and ammonia form red-brown precipitates of ferric hy-
drate, insoluble in an excess of the reagent. Potassium ferro-
cyanide forms a dark-blue precipitate which is Prussian blue.
Potassium ferricyanide produces a dark-brown color without
precipitation. Potassium sulphocyanate gives a blood-red color.
Solution of gall-nuts forms a bluish-black precipitate which
constitutes ink.
ZINC.
Zn 65.2
-
Treatment of Zinc Ores.-The zinc ores which are worked
are calamine and blende. Calamine is carbonate of zinc, often
mixed with silicate; it contains also oxide of iron. Blende is
sulphide of zinc; it frequently contains a small quantity of
ferrous sulphide, which gives it a brown color, more or less
intense.
Zinc ores are abundant in England, Silesia, Belgium, and
throughout the United States. They are generally accom-
panied by other minerals; thus, blende is often mixed with
pyrites and galena (lead sulphide). The ore is then first sub-
mitted to an ingenious system of washing, by which the various
sulphides separate from each other by reason of their different
densities.
In order to extract the zinc from blende separated by this
method, or from calamine, the minerals are first roasted. By
the action of heat calamine loses carbonic acid gas and water,
and the blende disengages sulphurous oxide and is converted
into zinc oxide. Thus converted into oxide, and rendered more
friable by the heat, the zinc ores are pulverized and calcined
with charcoal. Carbon monoxide is disengaged, and the zinc
set at liberty volatilizes, and is condensed in suitable recipients.
ZINC.
331
The operation is conducted in cylinders of refractory clay, a
number of which are arranged in a furnace, and their open
extremities connected with conical recipients of galvanized iron
(Fig. 105). In Silesia, these cylindrical retorts are replaced by
muffles, which are heated in a furnace and communicate with
recipients placed outside (Fig. 106).

"
1
W
M
offyi
44 14
ANAMA AAAAYYNU
WERWENTY
VAFNANGANANESSAN
ANAMGAYAES
111
IN
FIG. 105.
FIG. 106.
In England, the reduction of the roasted ore is accomplished
in crucibles, through the bottoms of which pass vertical tubes
which terminate in a reservoir below the furnace. The zinc
vapors first rise and then descend by
the tube, and as they condense, the
melted metal flows into the recipient.
The operation is called distillation per
descensum (Fig. 107).
The zine of commerce is not always
pure, especially when it occurs in
masses; it contains small quantities of
iron, copper, lead, cadmium, carbon,
and arsenic. Sheet zine is generally
less impure. Zine may be purified
by melting it several times with small
quantities of nitre.

FIG. 107.
Properties.-Zine has a bluish-
white color; its density varies from 6.86 to 7.2, according as
332
ELEMENTS OF MODERN CHEMISTRY.
it has been melted or rolled; its fracture is laminated and bril-
liant. Commercial zinc is brittle at ordinary temperatures; it
becomes malleable at a few degrees above 0°, but when heated
to 200° it again becomes brittle. It melts at 410°, and distils
at about 1000° (H. Deville and Troost). Its surface soon
tarnishes in moist air, but the oxidation is only superficial.
It is due to the formation of a hydrocarbonate of zinc, which
covers the metal with an impermeable surface and protects it
from further oxidation.
When heated to redness in contact with the air, zinc vola-
tilizes and burns with a greenish flame, being converted into
oxide, which rises as smoke and falls in very light, white flakes,
formerly called flowers of zinc or philosopher's wool.
Zinc dissolves with evolution of hydrogen in hydrochloric
and sulphuric acids, and in boiling solutions of potassium and
sodium hydrates. When perfectly pure, it is dissolved with
difficulty by dilute sulphuric acid at ordinary temperatures, and
the easy solubility of the metal of commerce must be attrib-
uted to the presence of small quantities of foreign metals. The
latter being electro-negative in contact with zinc, form voltaic
couples, in which the zinc is the more oxidizable metal.
Galvanized iron is iron covered with a thin layer of zinc; it
is prepared by plunging carefully-cleaned iron objects into a
bath of molten zinc.
Brass is an alloy of copper and zinc, obtained by melting the
two metals together in crucibles.
ZINC OXIDE.
ZnO
This oxide is prepared in the arts by heating zinc in large
muffles; the product is separated from traces of metallic zinc
by suspending it in water and rapidly decanting the white
liquid. The zinc sinks to the bottom of the vessel before the
lighter white powder has time to deposit; the latter is therefore
carried by the water into a second vessel, where it is allowed
to settle. The process is called elutriation.
Oxide of zinc is white; it is irreducible by heat and is insolu-
ble in water. A hydrate of this oxide is precipitated when an
alkali is added to the solution of a zinc salt.
ZnSO4 + 2KOH
K2SO4 + Zn(OH)²
Zinc sulphate.
Zinc hydrate.
ZINC SULPHIDE-ZINC CHLORIDE.
333
An excess of alkali will redissolve the precipitate.
Zinc oxide is largely used in the arts as a substitute for
white lead as a pigment.
ZINC SULPHIDE.
ZnS
It
The blende which occurs in nature is sulphide of zinc.
crystallizes generally in regular octahedra, sometimes in double
pyramids of six faces (Friedel).
On adding an alkaline sulphide to a neutral solution of a
zinc salt a white precipitate is obtained, which is hydrated zinc
sulphide.
When moderately heated in contact with the air, zinc sul-
phide absorbs four atoms of oxygen and is converted into sul-
phate. At a very high temperature it is converted into oxide,
with formation of sulphurous oxide.
ZINC CHLORIDE.
ZnCl2
Zinc
Zinc reduced to thin sheets will burn in chlorine.
chloride is prepared in the laboratory by dissolving zine in
hydrochloric acid. The aqueous solution, evaporated to a
syrupy consistence, deposits a hydrated chloride, ZnCl2 + H2O,
crystallizing in deliquescent octahedra. This salt loses its
water when strongly heated, and melts at about 250°. On
cooling, a solid white mass is obtained, which is the anhydrous
chloride; in this state it is very avid of water and deliquesces
when exposed to the air. It volatilizes without decomposition.
at a red heat. It is very soluble in water, and dissolves also
in alcohol.
ZINC SULPHATE.
ZnSO4 +7H2O
This salt was formerly known as white vitriol. It is ob-
tained by moderately roasting blende. The latter being often
mixed with pyrites, zine sulphate and ferrous sulphate are
formed, and when the product of the roasting is lixiviated a
solution of the two salts is obtained. The solution is evapo-
334
ELEMENTS OF MODERN CHEMISTRY.
rated, and the dry residue moderately calcined. The ferrous
sulphate decomposes, yielding sulphuric acid, which distils, and
ferric oxide, which remains mixed with the zinc sulphate. The
residue being exhausted with water, the zinc sulphate dissolves
and is deposited in crystals on the cooling of the concentrated
solution.
The salt may be prepared in the laboratory by dissolving
zinc in dilute sulphuric acid: it is the residue in the prepara-
tion of hydrogen.
Sulphate of zinc crystallizes with 7 molecules of water. In
this state it occurs as right rhombic prisms, isomorphous with
magnesium sulphate.
When heated, it melts in its water of crystallization, of
which it loses 6 molecules; the seventh it abandons only at
238°.
At a high red heat it is decomposed into zinc oxide, sul-
phurous oxide, and oxygen.
Zinc sulphate is very soluble in water, of which 100 parts
dissolve 48.36 parts of the anhydrous salt at 10°, and 95.6
parts at 100°. The solution has a styptic taste.
Zinc sulphate forms crystallizable double salts with the alka-
line sulphates; thus, there is a double sulphate of zinc and
potassium, containing
ZnSO¹.K2SO4 + 6H2O
Characters of Zinc Salts.-The zinc salts are colorless
unless the corresponding acid be colored. Their neutral solu-
tions are partially decomposed by hydrogen sulphide, which
precipitates white sulphide of zine; the addition of a mineral
acid prevents the precipitation; the zinc salts of organic acids,
such as the acetate and lactate, are completely decomposed by
hydrogen sulphide.
Ammonium sulphide produces a white precipitate of sul-
phide; this reaction is characteristic.
Potassium and sodium hydrates, and also ammonia, form
white precipitates, soluble in an excess of the reagent.
Potassium ferrocyanide gives a white precipitate.
GALLIUM.
335
GALLIUM.
Ga 69.9
This metal was discovered in 1876 by Lecoq de Boisbaudran.
It is contained in small quantity in certain blendes. One of
the richest, found in Westphalia, contains only one sixty-thou-
sandth of its weight.
In order to extract the gallium, the ore is roasted, and the
product dissolved in sulphuric acid. An acid liquor is thus
obtained, containing principally sulphate of zinc, with sulphates.
of iron, aluminium, indium, etc., and a trace of gallium sul-
phate.
The following reactions are employed by Lecoq de Bois-
baudran and Jungfleisch for the separation of the gallium :
1. When the liquid is neutralized, the ferric oxide, alumina,
and gallium oxide, which is a sesquioxide, are precipitated.
The precipitate is redissolved in sulphuric acid, and the same
operation repeated after converting the ferric oxide into ferrous
oxide, which remains dissolved in the neutral liquid.
means the greater part of the iron is removed.
By this
2. Gallium oxide dissolves, like alumina and zinc oxide, in
an excess of potassium hydrate; when this solution is saturated
with hydrogen sulphide, the zinc is precipitated as sulphide,
while the gallium and aluminium remain in solution. The
greater part of the zinc is thus separated.
3. When water is added to a boiling solution of gallium
sulphate, the latter is precipitated as subsulphate, while alumi-
nium sulphate remains in solution.
4. Gallium oxide dissolves in an excess of ammonia; alumina
does not.
5. Gallium separates in the metallic state when a voltaic
current is passed through an alkaline solution of gallium oxide.
Physical Properties.-Gallium has a metallic lustre recalling
that of nickel. It readily crystallizes in forms derived from a
right rhombic octahedron, generally in magnificent laminæ. Its
density is 5.96. It melts at 29.5°, and has a tendency to re-
main in a state of superfusion. It is not volatile.
This collection of properties gives to gallium a special place
among the metals. It is one of the most remarkable of recent
discoveries.
Chemical Properties.—These are but little known at present.
336
ELEMENTS OF MODERN CHEMISTRY.
Gallium is oxidized but little, if at all, when heated in the air
or in oxygen. It forms a sesquioxide, Ga'O³, which resembles
alumina in that it forms alums. Gallium alum was obtained
by Lecoq de Boisbaudran.
Gallium combines directly with chlorine, forming a solid,
crystalline, and very volatile chloride.
INDIUM.
In 113.4
This metal was discovered in 1863 by Reich and Richter
in the zinc blendes of Freiberg (Saxony). It appears to exist
in the majority of zinc blendes, and accompanies the zinc which
is extracted from those minerals. It is ordinarily obtained.
from metallic zinc, which, however, contains only very small
quantities of it. Commercial zinc (that of Freiberg is prefer-
able) is digested in a quantity of dilute sulphuric acid insuffi-
cient to dissolve all of the metal; after several weeks, a spongy
mass remains, which contains an excess of zinc and, indepen-
dently of other metals, a small quantity of indium. This is
the residue from which indium is obtained by processes which
need not be here described.
Indium is a brilliant metal, possessing almost the lustre of
silver. It is soft and ductile. It melts at 176°, and is vola-
tile, but less so than zinc and cadmium. It approaches these
metals in its general chemical properties, but is more electro-
negative, both of the latter metals precipitating it from its
solutions.
Indium is characterized by several spectroscopic lines, among
which are a very brilliant blue and a less marked violet line.
Winkler has indicated two other less distinct blue lines.
Two oxides of indium have been described, a sesquioxide,
In2O3, and a suboxide. The first is obtained by caleining the
nitrate; it is yellow. When heated to 300° in a current of
hydrogen, it is partially reduced, yielding a black suboxide.
Indium chloride, In'Cl, is formed when indium is heated
in a current of chlorine. It is a snow-white, volatile solid.
CADMIUM.
337
CADMIUM.
Ca - 112
Natural State and Extraction.-Cadmium is generally
found associated with zinc, either as oxide in calamine, or as
sulphide in zinc blende. As it is more volatile than zinc, it
becomes concentrated in the first products of distillation.
It is found especially, in the state of oxide, in the brown
powder called cadmies, which condenses during the first hours
of the distillation in the sheet-iron receivers adapted to the re-
torts (Fig. 105). When mixed with powdered charcoal and
calcined, this powder yields an alloy of zinc and cadmium
which distils.
The cadmium is extracted by dissolving the alloy in dilute
sulphuric acid and passing a current of hydrogen sulphide
through the acid liquid. The cadmium is precipitated as a
yellow sulphide. This sulphide is dissolved in hydrochloric
acid and the solution of cadmium chloride precipitated by am-
monium carbonate. The cadmium carbonate thus obtained is
calcined, and so converted into oxide, which is mixed with
one-tenth its weight of powdered charcoal and heated in a clay
retort. The cadmium distils.
Properties. Pure cadmium has a white lustre, but soon
tarnishes in the air. Its density is 8.60-8.69. It melts at
320° (Person), and boils at 860° (H. Deville and Troost). It
may be obtained crystallized in octahedra.
It dissolves in dilute sulphuric and hydrochloric acids with
evolution of hydrogen.
Cadmium Oxide, CdO.—The oxide of cadmium may be ob-
tained by calcining either the carbonate or nitrate.
It has a
yellowish-brown color, or a brown more or less deep. It is re-
duced at high temperatures by carbon and by hydrogen, its
reduction taking place more readily than that of zinc oxide.
Cadmium Sulphide, CdS.-This sulphide occurs in nature
in the form of bright yellow, hexagonal prisms, terminated by
six-sided pyramids.
It may be prepared in the laboratory by precipitating a solu-
tion of a cadmium salt by hydrogen sulphide or a soluble sul-
phide. An amorphous precipitate of a fine yellow color is thus
obtained. In this form it is employed in oil painting.
Cadmium Iodide, Cul.-This salt is prepared by digesting
P
29
338
ELEMENTS OF MODERN CHEMISTRY.
It
finely-divided cadmium with iodine in presence of water.
crystallizes from its aqueous solution in transparent and color-
less, hexagonal prisms having a brilliant lustre. It is soluble
in water and alcohol.
Cadmium Sulphate, CdSO + 4H2O.-Cadmium sulphate
is obtained by dissolving the metal, or its oxide or carbonate, in
dilute sulphuric acid. The neutral and concentrated solution
deposits the salt in beautiful, right rectangular prisms. These
crystals are efflorescent.
COBALT.
Co= 59
Cobalt was discovered by Brandt in 1753. It is found prin-
cipally in the state of arsenide, CoAs, and as sulph-arsenide,
CoASS (gray cobalt). Its ores are worked principally for the
production of a dark-blue, vitreous mass, a combination of
cobalt silicate and potassium silicate, known as smalt or azure
blue.
The metal is prepared in the laboratory by calcining its oxa-
late in a covered crucible.
CoC2O4
Cobalt oxalate.
Co + 2CO²
Carbon dioxide.
It may be obtained as a metallic button by heating the pul-
verulent metal in a lime crucible in a wind-furnace. The lime
crucible is placed in another crucible of refractory clay, and
the space between the two is filled up with fragments of quick-
lime (H. Sainte-Clairc Deville).
Pure cobalt is silvery-white. It is very malleable; its den-
sity is 8.6, and it is magnetic. At ordinary temperatures it is
unaffected by the air, but at a red heat it is converted into
oxide.
Oxides of Cobalt.-A monoxide, CoO, and a sesquioxide,
Co²O³, are known, and several intermediate oxides.
The monoxide may be obtained by calcining cobalt carbonate
in close vessels. It is a greenish-gray or olive-green powder,
which is reduced by hydrogen, charcoal, and carbon monoxide
at a red heat.
When heated with borax before the blow-pipe, it dissolves,
forming a blue glass. It is used for giving a blue color to
glass and porcelain.
COBALT.
339
When an excess of potassium hydrate is added to the solu-
tion of a salt of cobalt, a rose-red precipitate of cobalt hydrate,
Co(OH)2, is formed.
Cobalt sesquioxide, Co20³, is prepared by passing a current
of chlorine through water, holding in suspension the rose-
colored hydrate above mentioned.
2000 + H2O + Cl2 = Co²O³ + 2HCl
The sesquioxide is deposited as a black powder, which may
be dried by carefully heating it.
Cobalt Chloride, CoCl2.-When pulverulent cobalt is heated
in a current of chlorine, it takes fire and is converted into a
chloride, which sublimes in blue scales. A solution of this
chloride may be obtained by dissolving either monoxide or car-
bonate of cobalt in hydrochloric acid. The neutral solution is
currant-red, and on evaporation deposits hydrated crystals of
the same color. But when it is concentrated, after having
added hydrochloric or sulphuric acid, it becomes blue. This
change of color, due to the formation of anhydrous chloride
even in the midst of the hot liquid, has caused the employ-
ment of cobalt chloride as a sympathetic ink. Characters
traced with the dilute solution, which is rose-colored, are invisi-
ble on white paper, and appear blue only when the paper is
warmed, again becoming invisible on cooling, by the absorption
of atmospheric moisture.
Cobalt Sulphate, CoSO +7H2O.-This salt is found in
nature, crystallized in oblique rhombic prisms. It may be ob-
tained by dissolving the oxide or carbonate in dilute sulphuric
acid and concentrating the red solution. At ordinary temper-
atures, the latter deposits red crystals, isomorphous with ferrous
sulphate. Between 20 and 30°, it yields right rhombic prisms,
containing 6 molecules of water, and isomorphous with magne-
sium sulphate.
Characters of Cobalt Salts.-The cobaltous salts are the
more important. Their solutions are rose or currant-red, but
when concentrated and hot they become blue, especially when
an excess of acid is present. Hydrogen sulphide does not pre-
cipitate solutions of cobalt salts. Ammonium sulphide forms
a black precipitate. Potassium hydrate gives a blue precipitate
of a basic salt, which, in presence of an excess of potassa, is
converted into hydrate of cobalt, having a dirty rose color.
340
ELEMENTS OF MODERN CHEMISTRY.
Ammonia forms a blue precipitate, soluble in an excess of
the reagent.
When heated with borax in the blow-pipe flame, the salts of
cobalt yield beads of a pure blue color.
NICKEL
Ni 59
This metal was discovered by Cronstedt in 1751.
Natural State and Extraction.-Nickel is found as arsen-
ide, NiAs², in kupfernickel or nickeline. In the preparation of
smalt from the ores of cobalt, which always contain nickel, the
latter metal combines with the arsenic and a certain proportion
of sulphur, forming a metallic-looking mass known as speiss.
In the arts, nickel is extracted from kupfernickel or from
speiss. In the laboratory it is prepared by reducing the oxide
in a brasqued crucible, or by calcining the oxalate out of con-
tact with the air. When heated to whiteness in a lime cruci-
ble the nickel melts to a metallic button.
Properties. Pure nickel is grayish-white. It is malleable,
ductile, and very tenacious. Its density is 8.279, and may be
increased to 8.666 by hammering. Next to manganese, it is
the hardest of the metals. It is less fusible than iron and more
fusible than manganese. It is magnetic at ordinary tempera-
tures, but loses this property at about 250°. It is unaltered by
the air at ordinary temperatures, but absorbs oxygen at a red
heat. It dissolves slowly in dilute sulphuric and hydrochloric
acids, rapidly in nitric acid. In contact with concentrated nitric
acid it becomes passive like iron.
Nickel is used in the arts, in the manufacture of an alloy
known as German silver, which contains 50 per cent. of copper,
25 of nickel, and 25 of zinc.
Nickel may be deposited as a brilliant metallic layer by the
electrolysis of a solution of nickel and ammonium double sul-
phate (A. C. and E. Becquerel). Adams made an application
of this property to the nickel-plating of various objects by
electro-metallurgy, and the process is now largely employed.
Oxides of Nickel.-A monoxide, NiO, and a sesquioxide,
Ni20³, are known.
The anhydrous monoxide is an ash-gray powder. It is
obtained by strongly calcining the nitrate or carbonate. On
NICKEL.
341
adding potassium hydrate to a nickel salt, an apple-green pre-
cipitate of nickel hydrate, Ni(OH)2, is formed.
Nickel sesquioxide may be obtained by moderately calcining
the nitrate. It is black. When chlorine gas is passed into
water holding nickel hydrate in suspension, a dark-brown pow-
der is obtained, which is a hydrate of the sesquioxide. This
hydrate may also be made by precipitating a nickel salt with
potassium hydrate mixed with an alkaline hypochlorite.
When strongly calcined, nickel sesquioxide abandons part of
its oxygen and is changed into monoxide. Treated with hydro-
chloric acid, it yields nickel chloride, and chlorine is disengaged.
Ni20³ + 6HCI 2NiCl2 + 3H2O + Cl²
Nickel Chloride, NiCl2.-This salt may be obtained anhy-
drous by the action of chlorine on nickel-filings; it is volatile
at a dull-red heat, and sublimes in golden-yellow scales. The
hydrated chloride is formed by the action of boiling water on
the anhydrous salt, or by the action of hydrochloric acid on the
oxide or carbonate. Its solution is green, and after proper
concentration deposits beautiful green crystals which contain
NiCl2 + 9H2O.
Nickel Sulphate, NiSO +7H2O.—The sulphate is depos-
ited in fine, emerald-green, orthorhombic prisms, isomorphous
with magnesium sulphate, when its solution is allowed to evap-
orate spontaneously below 15°. There is another hydrate con-
taining 6H2O, which is dimorphous. When deposited between
20 and 30°, it crystallizes in square octahedra, but when its
solution is made to crystallize between 60 and 70°, right rhom-
bic prisms are obtained, isomorphous with the corresponding
sulphates of magnesium, zinc, and cobalt.
Nickel sulphate dissolves in 3 times its weight of water at 10°.
Characters of Nickel Salts.-The nickel salts when hy-
drated or in solution have a fine emerald-green color. When
anhydrous they are yellow.
Hydrogen sulphide does not precipitate them from acid solu-
tions. Ammonium sulphide throws down a black precipitate.
Potassium hydrate and potassium carbonate form apple-green
precipitates.
In neutral solutions, ammonia gives a green precipitate of
nickel hydrate, which dissolves in an excess of ammonia, form-
ing a blue solution.
29*
342
ELEMENTS OF MODERN CHEMISTRY.
MANGANESE.
Mn 55
This metal has been obtained as a coherent, very hard mass,
by reduction of either manganous carbonate or red oxide of
manganese with charcoal or sugar in a lime crucible at the
highest heat of a wind-furnace (H. Deville).
It is whitish-gray, and almost as infusible as platinum. Its
density is 7.2. Its powder decomposes warm water.
MANGANESE OXIDES.
Manganese forms six compounds with oxygen:
Manganous oxide.
Manganoso-manganic oxide
Manganic oxide
•
Manganese dioxide
Manganic anhydride
Permanganic anhydride
MnO
Mn30
Mn203
MnO2
Mn 03
Mn207
Manganous oxide is formed when manganous carbonate is
strongly heated in a current of hydrogen. Carbon dioxide is
evolved, and a green powder, which is manganous oxide, re-
mains. It takes fire on contact with an incandescent body, and
is converted into a brownish-red powder, which is red oxide of
manganese.
3 MnO + O
Mn³O
The latter body is also formed by the calcination of the diox-
ide. It is analogous to the magnetic oxide of iron, and con-
stitutes the mineral 'known as hausmannite.
Manganic oxide, Mn2O3, occurs in nature in the crystallized
state as braunite. It is isomorphous with alumina and ferric
oxide.
MANGANESE DIOXIDE.
(BINOXIDE OR PEROXIDE OF MANGANESE.)
MnO2
This important body is found abundantly in nature; it con-
stitutes the mineral pyrolusite. It may be obtained pure and
anhydrous by exposing a concentrated solution of manganous
nitrate to heat and gradually raising the temperature to 155°.
MANGANIC ACID.
343
Nitrous vapors are evolved, and a brilliant brown-black mass is
obtained, which is the dioxide.
Mn(NO³)²= MnO² + 2NO²
It loses one-third of its oxygen when heated to redness, and
is converted into the red oxide. When heated with concen-
trated sulphuric acid, it loses half of its oxygen, manganous
sulphate being formed,
MnO2 + H2SO¹
MnSO4 + H2O ÷ 0
With hydrochloric acid it yields water, chlorine, and manga-
nous chloride.
A hydrate of manganese dioxide is formed when an excess
of chlorine is directed into water holding in suspension man-
ganous hydrate or carbonate. This hydrate is a dark-brown
powder.
Manganese dioxide is largely employed for the preparation
of oxygen and chlorine. It is used to decolorize glass black-
ened by carbonaceous matters or rendered green by a trace of
iron.
MANGANIC ACID.
When manganese dioxide is heated with potassium hydrate
in a silver crucible, and the calcined mass is exhausted with
water, the latter dissolves out potassium manganate. A dark-
green liquor is thus obtained which, when evaporated in vacuo,
deposits a crystalline mass. These crystals may be drained on
a porous porcelain plate, and green needles of potassium man-
ganate, KMnO¹, remain. The salt is isomorphous with the
sulphate K2SO¹.
When the green solution is boiled, it becomes red and deposits
brown flakes of hydrated manganese dioxide: the red liquor is
a solution of potassium permanganate, this salt being formed at
the expense of the manganate, which breaks up into hydrated
dioxide, potassium hydrate, and permanganate.
3K²MnO¹ + 3110 = K²Mn2O + MnO².H2O + 4KOH
Potassium Hydrated manganese
permanganate.
Potassium
manganate.
dioxide.
An analogous decomposition takes place when an acid is
added to the green solution of manganate; a manganous salt
and permanganic acid are formed, and the latter colors the
liquid red.
344
ELEMENTS OF MODERN CHEMISTRY.
PERMANGANIC ACID.
Potassium permanganate, K'Mn208, is an important salt. It
may be prepared by introducing into an iron crucible 5 parts
of caustic potassa with a small quantity of water, then a mix-
ture of 3 parts of potassium chlorate and 4 parts of finely-
powdered manganese dioxide. The mixture is heated and
continually stirred, until the mass becomes dry and the tem-
perature has reached dull redness. After cooling, the product
is pulverized and introduced into 200 parts of boiling water.
When the liquid has assumed a purple color, it is allowed to
stand, decanted, and after neutralization by nitric acid, is
evaporated at a gentle heat. On cooling, it deposits crystals
that may be dried on a porous tile.
Potassium permanganate crystallizes in almost black needles,
having a metallic reflection. It dissolves in 15 or 16 parts of
cold water, and its solution has a magnificent, intense purple
color.
If solution of sulphurous acid be added to potassium per-
manganate solution, the latter is instantly decolorized, and the
liquid contains only potassium sulphate and manganese sulphate.
If a drop of the solution of potassium permanganate be
placed upon a sheet of paper, it loses its color and a brown
stain of hydrated manganese dioxide is produced.
These experiments indicate the oxidizing properties of the
permanganate. In the first, sulphurous acid was oxidized; in
the second, it was paper, of which the carbon and hydrogen
removed the oxygen from the permanganate, which was thus
reduced to dioxide.
MANGANOUS SULPHATE.
MnSO4 +7H2O
This salt may be prepared by dissolving manganous carbon-
ate in sulphuric acid. The properly concentrated rose-colored
solution deposits, between 0 and 6°, oblique rhombic prisms,
isomorphous with green vitriol and containing 7 molecules of
water.
Between 7 and 20°, manganous sulphate crystallizes with 5
MANGANOUS CARBONATE.
345
molecules of water, like cupric sulphate, with which it is then
isomorphous.
Between 20 and 30°, it is deposited in oblique rhombic
prisms, according to Marignac, which contain only molecules
of water.
All of these crystals are rose-colored, and their color is
deeper as they contain more water of crystallization. They are
very soluble in water.
MANGANOUS CARBONATE.
Mn CO3
The residues from the preparation of chlorine may be used
for making this salt. They are evaporated, without filtering,
in a porcelain capsule, with frequent stirring, and the dry
residue is calcined with an excess of manganese dioxide. The
ferric chloride which was mixed with the manganous chloride
is decomposed or volatilized during this operation. Ferric
oxide remains, mixed with the excess of manganese dioxide
and the manganous chloride, which resists the heat. The latter
is extracted by exhausting the mass with boiling water. A
rose-colored solution is thus obtained which often contains a
small quantity of cobalt chloride. The latter is precipitated.
as sulphide by adding little by little a solution of sodium sul-
phide. As soon as the precipitate, which is at first blackish,
begins to assume a flesh tint, the liquid is filtered and precipi-
tated by sodium carbonate.
Manganese carbonate constitutes a white powder with a pale
rose tint. When heated in contact with air, it gives up car-
bonic acid gas and is converted into red oxide of manganese.
Characters of Manganese Salts.-The salts of manganese
are colorless or have a light rose color. Their solutions are
not precipitated by hydrogen sulphide. Ammonium sulphide
gives a flesh-colored precipitate; sodium carbonate, a dirty
white. Potassium hydrate produces a dirty white precipitate
of manganous hydrate, which rapidly becomes brown by ab-
sorbing oxygen from the air.
When heated in the blow-pipe flame with a small quantity
of potassium hydrate or nitrate, the salts of manganese give a
bead which dissolves in water with a green color (manganate).
p*
346
ELEMENTS OF MODERN CHEMISTRY.
CHROMIUM.
Cr
52.5
Chromium was discovered in 1797, by Vauquelin, in a min-
eral formerly known as red lead of Siberia, and which is
chromate of lead. It forms one of the elements of chrome
iron, a combination of chromium oxide with ferrous oxide,
Cr²O³. FeO, which corresponds to magnetic oxide of iron,
Fe2O3.FeO.
H. Deville isolated the metal by calcining chromium oxide
with charcoal and linseed oil in crucibles of lime and charcoal.
Thus prepared, chromium forms grayish-white, metallic grains,
which are brittle, as hard as corundum, and have a density of
5.9.
This metal does not oxidize in the air at ordinary tempera-
tures. At a red heat, it is converted into the oxide Cr2O³.
When thrown into potassium chlorate in a state of fusion, it
burns with a dazzling white flame, a chromate being formed.
It burns in the same manner in chlorine gas, being transformed
into a violet chloride. It dissolves in hydrochloric acid, disen-
gaging hydrogen.
COMPOUNDS OF CHROMIUM AND OXYGEN.
There are two well-defined compounds of chromium and
oxygen, the green oxide of chromium, Cr2O3, and chromic
anhydride, Cro³
Chromium Oxide, Cr2O3, is a green powder; it may be
obtained by calcining mercurous chromate.
2Hg2CrO4Hg + 05 + Cr20³
Another process consists in heating in a crucible a mixture
of 2 parts of potassium dichromate with a little more than 1
part of flowers of sulphur. After cooling, the mass is treated
with water, which dissolves out potassium sulphate and leaves
chromium oxide.
Fremy obtained it in small crystals by passing chlorine gas
over potassium chromate heated to redness, and exhausting the
cooled mass with water.
Chromium oxide is undecomposable by heat, and melts only
at the temperature of the forge. It forms several different
CHROMIC ANHYDRIDE-CHROMATES.
347
hydrates. When ammonia is added to the green solution of
chromic chloride, a green, flaky precipitate of chromic hydrate
is formed; it is soluble in acids and in potassium hydrate.
Chromic Anhydride, CrO³, is prepared by gradually adding
to a cold saturated solution of potassium dichromate 1½ times
its volume of sulphuric acid. The chromic anhydride, ordina-
rily called chromic acid, set free separates in needle-shaped
crystals of a dark-red color, which should be drained and re-
crystallized in a small quantity of warm water.
It is deliquescent; its aqueous solution has a dark yellow-
brown color. It is an energetic oxidizing agent. Hydrochlo-
ric acid converts it into chromic chloride, with evolution of
chlorine.
2CrO3 + 12HCI
Cr²C16 + 6H2O + 3C1²
If a concentrated solution of sulphurous acid be added to a
solution of chromic acid, the liquid immediately becomes green
from the formation of chromic sulphate.
Chromates. The most important chromates are those of
potassium and lead.
Potassium neutral chromate, K2CrO, crystallizes in lemon-
yellow, right rhombie prisms, isomorphous with potassium sul-
phate. It is very soluble in water, to which it communicates
an intense yellow color. So great is its coloring property, that
one part of chromate will sensibly color 40,000 parts of water.
Potassium dichromate, K²Cr2O7, is prepared by heating to
redness 2 parts of chrome iron with 1 part of nitre. The mass
is exhausted with water, which dissolves out potassium neutral
chromate; acetic acid is added to this solution, precipitating
the silica, which is derived from the crucible and remains in
the solution as silicate, and removing one-half of the potassium
from the chromate, thus converting it into the dichromate.
The latter crystallizes out on evaporation.
Potassium dichromate is a beautiful salt of an orange-red
color. It crystallizes in quadrangular tables derived from a
dissymetric prism.
It dissolves in 8 or 10 parts of cold water and in a much
less quantity of boiling water.
A strong heat decomposes it into neutral chromate, chromium
oxide and oxygen.
2K²Cr²O² = 2K²CrOª + Cr²O³ + 0³
348
ELEMENTS OF MODERN CHEMISTRY.
When heated with sulphuric acid, it loses oxygen and is
converted into chromic sulphate and potassium sulphate.
K2Cr2O7+ 4H SO' Cr²(SO) + K2SO4 + 4H2O +0
K²SO* 0³
The residue when exhausted with water yields a green solu-
tion, which deposits on evaporation beautiful octahedral crystals
of a violet-black color, constituting chrome alum.
Cr²(SO¹)³.K SO' + 24H2O
Sulphurous acid reduces potassium dichromate in the cold,
also yielding chrome alum if sulphuric acid be added.
K2Cr2O + 3S0² + H2SO¹ Cr²(SO¹)³.K²SO¹ + H2O
The constitution of potassium dichromate is represented by
the formula
KOCrO2
KOCrO2
COMPOUNDS OF CHROMIUM AND CHLORINE.
Several combinations of chromium and chlorine are known.
The most important is the violet chloride, Cr²C16, correspond-
ing to aluminium chloride and ferric chloride. It is prepared
by passing chlorine gas over an intimate and perfectly dry
mixture of chromium oxide and charcoal, heated to redness in
a porcelain tube; carbon monoxide is disengaged, and chromic
chloride sublimes into the cooler portion of the tube in brilliant
peach-blossom-colored scales.
These crystals are almost insoluble in cold water, and dis-
solve but slowly in boiling water. Hydrogen reduces them at a
red heat, with formation of hydrochloric acid, and a chloride,
Cr2 Cl*, which crystallizes in white scales (Peligot).
Cr²Cl® + H2 2HCl + Cr²Cl⭑
If a small quantity of the chloride Cr²Cl, be added to hot
water, holding in suspension the violet chloride, Cr²Cl, the
latter will be instantly dissolved, forming a green solution.
Chlorochromic anhydride, CrO'Cl", is obtained by heating a
previously fused mixture of common salt and potassium di-
chromate with sulphuric acid; abundant red vapors are disen-
BISMUTH.
349
gaged, and condense to a blood-red liquid. This body boils.
at 116.8°. Its density at 25° is 1.920 (Thorpe). On contact
with water it decomposes into hydrochloric acid and chromic
anhydride.
CrO2Cl2 + H2O = CrO³ + 2HCl
BISMUTH.
Bi 210
Extraction. This metal is found native in a quartzy gangue.
It is extracted by simply heating the mineral in cast or sheet
iron tubes, which are arranged in an inclined position in a fur-
nace. The bismuth melts and runs out at an opening in the
lower end of the tubes.
The bismuth of commerce is never pure; it contains traces
of other metals, nearly always of arsenic and sometimes of
sulphur. It is purified by pulverizing it, mixing it with
its weight of potassium nitrate, and heating the mixture to
redness in a clay crucible. The foreign metals more oxidiza-
ble than the bismuth are thus converted into oxides, the ar-
senic into arsenate of potassium, and the sulphur into potassium
sulphate. This treatment may be repeated a second time if
necessary.
Properties.-Bismuth is a whitish-gray metal, having a yel-
low lustre. Its fracture is crystalline and laminated. Its den-
sity is 9.83, and it melts at 264°. On cooling, it crystallizes
in rhombohedra, of which the surfaces become covered with a
thin film of oxide, causing a beautiful iridescent play of colors
like that on a soap-bubble.
Bismuth increases in volume on solidifying. It volatilizes at
a white heat. It is unaltered by the air at ordinary tempera-
tures, but at a red heat it absorbs oxygen and burns, forming
bismuth oxide. Its best solvent is nitric acid, which converts
it into nitrate.
The various compounds of bismuth present great analogy to
those of antimony, next to which this metal might be placed
in the group including nitrogen, phosphorus, arsenic, antimony,
and bismuth.
30
350
ELEMENTS OF MODERN CHEMISTRY.
This analogy is shown in the following synoptic table :
Bi205
BiCl³
SbCl³
Bismuth trichloride.
Antimony trichloride.
Bi203
Sb2O3
Bismuth trioxide.
Antimony trioxide.
Sb2O5
Antimonic anhydride.
Sb2O+
Antimony antimonate.
Sb2S3
Antimony trisulphide.
Bismuthic anhydride.
Bi20¹
Bismuth bismuthate.
Bi2S3
Bismuth trisulphide.
Otherwise, bismuth is related to the metals proper, not only
by its properties, but by the facility with which it forms defi-
nite salts. It is triatomic in its more important combinations,
the oxide, chloride, and nitrate.
BISMUTH TRIOXIDE.
Bi203
This body is obtained by decomposing the nitrate by heat.
It is a straw-yellow powder, fusible at a red heat, and yielding
on cooling a dark-yellow, vitreous mass. It attacks clay cruci-
bles even more rapidly than litharge.
A hydrated oxide of bismuth is formed when the nitrate or
subnitrate is treated with potassium hydrate or ammonia. It
is a white powder, insoluble in an excess of alkali, and when
boiled with potassa, is converted into the crystalline anhydrous
oxide.
BISMUTH TRICHLORIDE.
BiC13
Finely-divided bismuth will burn in chlorine, being con-
verted into chloride. The latter is prepared by directing a
current of chlorine upon melted bismuth contained in a retort.
The chloride distils and solidifies in the receiver to a fusible,
crystalline, and deliquescent mass, formerly known as butter
of bismuth. A crystallized, hydrated chloride of bismuth may
also be obtained by evaporating a solution of bismuth in nitro-
hydrochloric acid.
Bismuth chloride dissolves in water charged with hydro-
chloric acid, but is decomposed when treated with pure water;
BISMUTH NITRATE.
351
in the latter case an oxychloride is formed and precipitated as
a fine, white powder, hydrochloric acid being at the same time
formed.
2BiCl³ + 2H2O = 2BiOCI + 4HCl
Bismuth oxychloride is known as pearl-white. It contains
BiOCI.
BISMUTH NITRATE.
Bi(NO3)3
Bismuth dissolves readily in nitric acid, and the concentrated
solution deposits large, four-sided prisms, which are colorless
and deliquescent. They contain Bi(NO3)3 + 3H2O. They
are very soluble in water acidulated with nitric acid, but if this
solution be poured into a large excess of water, a pulverulent,
white precipitate is formed, and increases in volume if very
dilute ammonia be gradually added to the liquid in order to
partly neutralize the free acid.
This precipitate is much employed in medicine under the
name of subnitrate of bismuth. Its composition is generally
expressed by the formula BiNO + H³O = (BiO)'NO³ +
H²Ô
H2O.
It may be regarded as bismuthyl nitrate, that is, nitric
acid, HNO³, in which the monobasic atom of hydrogen is re-
placed by the monatomic group BiO. Or it may be considered
as a derivative of orthonitric acid, H³NO*, corresponding to
orthophosphoric acid, H³PO¹ (page 191).
Boiling water removes still more nitric acid from this sub-
nitrate, leaving a residue, which is used as a cosmetic, known as
blanc de fard.
Characters of Solutions of Bismuth.-When mixed with
a large quantity of water, bismuth solutions give white pre-
cipitates of sub-salts. Hydrogen sulphide, and the soluble.
sulphides form a brown precipitate of bismuth sulphide, insolu-
ble in an excess of ammonium sulphide. The alkaline hydrates
and carbonates give white precipitates, insoluble in an excess
of the reagent.
Bismuth solutions are not precipitated by either sulphuric
or hydrochloric acid.
When heated with sodium carbonate in the reducing flame of
the blow-pipe, compounds of bismuth yield a metallic globule,
very brittle after cooling.
352
ELEMENTS OF MODERN CHEMISTRY.
TIN.
Sn (Stannum) = 118
Natural State and Extraction.-The only mineral of tin
which is worked is the dioxide (cassiterite). It is found in
veins in the oldest formations, or disseminated in sand produced
by their disaggregation. The principal tin mines are in India,
in Malacca and the island of Banca, in Wales and in Saxony.
Tin ore generally occurs mixed with various other minerals,
such as sulphide and sulph-arsenide of iron, sulphides of copper
and tin, etc. It is crushed and washed in order to remove
light, earthy matters, and then roasted. The sulphides and
sulph-arsenides are thus oxidized and disintegrated, and the
D
product is submitted to a sec-
ond washing which removes
the lighter oxides, leaving the
cassiterite. The latter is then
heated with charcoal in а
cupola-furnace, represented in
Fig. 108; it is a sort of pris-
matic furnace, having a hearth
at the bottom where the melted
metal collects. Air is blown
in through the tuyère D. Car-
bon monoxide is formed, and
this reduces the stannic oxide;
the tin collects on the hearth,
from which it is drawn into
the basin I, where it is stirred
with rods of green wood. The
steam and gases produced by
the carbonization of the wood, agitate the melted mass and bring
to the surface the foreign matter or dross, which is removed.
The tin is then run into moulds.

FIG. 108.
Thus obtained, tin generally contains small quantities of
copper, iron, lead, antimony, and arsenic. It is purified by
slowly heating it on the hearth of a reverberatory furnace;
the pure tin melts first and runs out of the furnace, while the
less fusible alloys remain upon the hearth. This method of
purification is called liquation.
Properties. Pure tin is a white metal, resembling silver in
TIN.
353
its color and lustre. It melts at 228°, and crystallizes when
slowly cooled. Crystals of tin, belonging to the type of the
right square prism, may also be obtained by galvanic precipi-
tation of the metal. Their density is 7.178. That of the
fused and slowly-cooled metal is 7.373 (H. Deville).
Tin is ductile and malleable. When a bar of tin is bent,
it produces a peculiar noise called the cry of tin.
The metal is unaltered by the air, but when fused, rapidly
becomes covered with a grayish pellicle of oxide. Tin dis-
solves in concentrated hydrochloric acid, disengaging hydrogen.
The action is rapid when heat is applied.
If ordinary nitric acid be poured upon granulated tin, an
energetic action takes place immediately. The tin is converted
into a white powder of dioxide, and torrents of red vapors are
evolved.
Very dilute nitric acid attacks tin almost without disengage-
ment of gas.
After some time the liquid will be found to con-
tain a small quantity of tin nitrate and ammonium nitrate.
The ammonia is formed by the simultaneous reduction of water
and nitric acid by the tin.
HNO3 + HẢO = 2O + NH3
+
When tin is heated with a concentrated solution of either
potassium or sodium hydrate, hydrogen is disengaged, and an
alkaline stannate is formed.
Uses of Tin.-Tin enters into the composition of bronzes;
it is made into dishes and covers, and the thin foil in which
various substances, such as chocolate and tobacco, are enveloped.
Tinning of kitchen vessels consists in covering them with a
thin coating of tin. This protects the copper or iron from the
action of the acids which enter into the composition of various
articles of food. The objects to be tinned are first well cleaned
by rubbing them with sand, and are then dipped into melted
tin. After separating the excess of metal, they are polished
by rubbing with cloths dipped in sal ammoniac.
Tin-plate is sheet-iron covered with a thin layer of tin. The
iron is first dipped into dilute sulphuric acid to remove the
oxide; it is then rubbed with sand, and afterwards plunged
successively into a bath of melted tallow and a bath of tin covered
with tallow. On contact with the iron, the tin enters into com-
bination, forming a true alloy, which becomes covered with a
coating of pure tin.
30*
354
ELEMENTS OF MODERN CHEMISTRY.
When the surface of tin-plate is washed with a mixture of
hydrochloric and nitric acids, the superficial coat of tin is dis-
solved, and the crystallized alloy of tin and iron is exposed.
This is called crystallized tin-plate.
COMPOUNDS OF TIN AND OXYGEN.
Tin forms two compounds with oxygen, stannous oxide, SnO,
and stannic oxide, SnO2. The first is of but little importance.
It is obtained by precipitating a solution of stannous chloride
by potassium hydrate, and boiling the precipitate, by which the
white, stannous hydrate first formed is converted into a black
crystalline powder of stannous oxide. When this substance is
heated to 250°, it decrepitates, increases in volume, and becomes
converted into an olive-brown powder, which is a dimorphous
modification of the black oxide.
STANNIC OXIDE.
SnO2
This body is found in nature in the form of beautiful, hard,
transparent crystals of a yellowish-brown color, belonging to
the type of the square prism.
The white powder obtained when the metal is treated with
nitric acid is a stannic hydrate, which plays the part of an acid,
and was named by Fremy metastannic acid. He attributes to
it the composition 5(H*SnO¹). It would be a polymere of
normal stannic acid.
Sn
H*
04
(OH)'Sniv
When heated to 100°, this hydrate loses half of its water;
at a red heat, it loses the remainder and is converted into stannic
oxide.
►
When ammonia is added to an aqueous solution of stannic
chloride, a white, gelatinous precipitate is formed, constituting
a hydrate.
H2SnO³ =
Sniv)
03
H2
This is the stannic acid of Fremy. It dissolves readily in
hydrochloric acid, and the solution behaves as would an aqueous
solution of stannic chloride.
H'SnO³ + 4HCl
SnCl4 + 3H2O
SULPHIDES OF TIN-STANNOUS CHLORIDE.
355
It reacts with the bases, forming stannates of which the
general composition is expressed by the formula:
R2SnO³
Sn
R2
}
03
When heated to 140°, or even when dried for a long time
in a vacuum, it becomes insoluble in acids.
SULPHIDES OF TIN.
Two sulphides of tin are known: a monosulphide, SnS, and
a disulphide, SnS2. The first is obtained by heating tin-filings
with flowers of sulphur: the product still contains an excess
of tin, and it is necessary to again heat it with a fresh quantity
of sulphur. It is a crystalline, lead-colored mass.
Tin disulphide or stannic sulphide is prepared by first making
an amalgam of 12 parts of tin and 6 parts of mercury; this is
pulverized and the powder is mixed with 7 parts of flowers of
sulphur and 6 parts of sal-ammoniac. The mixture is intro-
duced into a matrass of green glass and gradually heated to
dull redness on a sand-bath. Sulphur, sal-ammoniac, sulphide
of mercury, and stannous sulphide are condensed in the upper
part of the matrass, of which the interior becomes covered with
a yellow crystalline mass of stannic sulphide. The presence
of sal-ammoniac and mercury, which volatilize in this opera-
tion, prevents an elevation of temperature, which would decom-
pose the stannic sulphide. The latter is carried with their
vapors, and condenses in brilliant, gold-like scales, which are
greasy to the touch. This body is known as mosaic gold. It
is decomposed by a red heat into stannous sulphide and sul-
phur. It is used for coating the cushions of electric machines.
STANNOUS CHLORIDE.
SnCl2
This compound may be prepared anhydrous by heating tin
in hydrochloric acid gas. Hydrogen is evolved, and a white
or grayish mass remains, which has a greasy appearance, and
is almost transparent. It fuses at 250°. This is stannous
chloride.
When tin is dissolved in hot, concentrated hydrochloric acid
and the limpid solution is evaporated and allowed to cool,
beautiful transparent crystals are obtained, which contain
356
ELEMENTS OF MODERN CHEMISTRY.
SnCl² + 2H2O. This is known in commerce as tin salt or tin
crystals.
The crystals of stannous chloride dissolve in a small quan-
tity of water, forming a limpid liquid, but when treated with
a large quantity of water, they yield a cloudy liquid, which
holds in suspension a small quantity of white oxychloride.
The atmospheric oxygen dissolved in the water takes part in
this decomposition of stannous chloride, from which it removes
part of the metal, a corresponding quantity of stannic chloride
(tetrachloride) being formed.
Stannous chloride reduces many oxygenized and chlorinated
compounds. It decomposes the salts of silver and mercury,
setting free the metal. It instantly decolorizes the purple
solution of potassium permanganate.
If a solution of stannous chloride be added to a solution of
corrosive sublimate (mercuric chloride), a white precipitate of
calomel (mercurous chloride) is instantly formed. By adding
an excess of stannous chloride, all of the chlorine may be re-
moved from the mercuric chloride, and a gray precipitate of
metallic mercury will be formed.
Stannous chloride is employed as a mordant in dyeing.
STANNIC CHLORIDE (TETRACHLORIDE OF TIN).
SnCl4
If thin tin-foil be thrown into a jar of chlorine gas, the
metal will take fire, and in presence of an excess of chlorine
will be converted into anhydrous stannic chloride. This is
liquid, and gives off white fumes in the air. It was formerly
known as fuming liquor of Libavius.
It is prepared by passing dry chlorine upon tin contained in
a small retort. The anhydrous chloride condenses in the re-
cipient in the form of a yellow liquid. It may be decolorized
by rectification with a small quantity of mercury, which removes
the excess of chlorine.
A
Tin tetrachloride boils at 120°. Its density is 2.28.
small quantity of water added to it is absorbed with a hissing
noise, and the formation of a crystalline deposit of a hydrate,
SnCl4 + 5H2O.
These crystals may also be obtained by dissolving tin in aqua
regia and evaporating the solution, or, again, by passing chlo-
LEAD.
357
rine into a solution of stannous chloride and concentrating the
solution.
The crystals of hydrated stannic chloride dissolve in water,
forming a clear solution.
Characters of Stannous Solutions.-Brown precipitates
are formed by both hydrogen sulphide and ammonium sulphide;
the precipitate dissolves in an excess of the latter reagent.
Potassium hydrate forms a white precipitate, soluble in an
excess of potassa; ammonia yields a white precipitate, insoluble
in excess.
An excess of stannous chloride produces a gray precipitate
of metallic mercury in a solution of mercuric chloride.
Chloride of gold gives a purple precipitate (purple of Cas-
sius) in dilute stannous solutions.
Characters of Stannic Solutions.-Hydrogen sulphide and
ammonium sulphide form yellow precipitates, soluble in a large
excess of the latter reagent. Potassa, soda, and ammonia,
all form white precipitates, disappearing in an excess of the
reagent.
Chloride of gold does not precipitate stannic solutions.
A sheet of iron or zinc will precipitate the tin from either
stannous or stannic solutions in gray scales, which assume the
metallic lustre when burnished.
LEAD.
Pb(Plumbum)
207
Treatment of Lead Ores.-The minerals of lead which are
worked are the carbonate, and especially the sulphide, known as
galena.
The extraction of the metal from the carbonate is simple:
it is heated with charcoal in a cupola-furnace, and the reduced
lead collects on the hearth.
Two methods are employed for the reduction of galena.
One consists in melting the ore with iron (granulated cast iron).
Sulphide of iron is formed, and both it and the reduced lead
enter into fusion and separate from each other by virtue of
their different densities, the lead being much the heavier.
This is the reduction method. It is employed for impure ores
having a silicious gangue.
By the other process, known as the reaction method, the
358
ELEMENTS OF MODERN CHEMISTRY.
galena is first roasted, by which the sulphide is partially trans-
formed into oxide and sulphate; the openings of the furnace
are now closed and the temperature is clevated. The excess
of sulphide then reacts upon the oxide and upon the sulphate;
sulphurous acid gas is disengaged, and metallic lead is formed.
This is called work-lead.
PbS+ 2PbO
PbS+ PbSO¹
3Pb + SO²
2Pb + 2S02
The operation is conducted in a reverberatory furnace repre-
sented in Fig. 109. The ore is spread in thin layers on the

A
师
​D
D
D
E
ད་ང་ ་་་་་་། ་་་ ་
FIG. 109.
hearth E, and heated to dull redness; the fire is at A, and the
air enters by the openings D. These are closed when it is
judged by the aspect of the mass that the roasting is suffi-
ciently advanced. The heat is then increased.
Independently of the portion of lead sulphide which reacts
upon the oxide and sulphate, there is always an excess, which
melts when the heat is increased, and separates in the form of
lead matt. This is subjected to another operation by the same
process of reaction, and furnishes a harder lead than that first
obtained; it contains a small quantity of copper, and is known
as slag lead.
In some works, charcoal-powder is added at a certain stage
of the roasting, to remove the oxygen from the oxide and sul-
phate formed.
LEAD.
359
Treatment of Argentiferous Lead. The lead produced by
these methods, and especially the work-lead, often contains a
small proportion of silver. In order to separate the latter
metal, the lead is submitted directly to cupellation, or is first
refined by way of crystallization before the cupellation.
The object of refining by crystallization is the formation of
an alloy of lead and silver, richer in silver than the work-lead.
The argentiferous lead is melted and allowed to cool slowly;
nearly pure lead separates in the form of crystals, which are
deposited at the bottom of the molten metal. These are re-
moved by a ladle as fast as they are formed; the richer alloy

EF EFFLEE
IWAS
FIG. 110.
of lead and silver remains liquid. The crystals of lead still
contain a little silver, and are submitted to another fusion; lead
again crystallizes out on cooling, and a small quantity of an
alloy still rich in silver is obtained. The same operation re-
peated a third time determines the separation of pure lead.
The alloys of lead and silver thus obtained are themselves sub-
mitted to several successive fusions and crystallizations, and a
still richer alloy results.
·
The alloy thus concentrated is cupelled. The operation con-
sists in melting the lead in a reverberatory furnace (Fig. 110),
。
360
ELEMENTS OF MODERN CHEMISTRY.
of which the hearth has a hemispherical form, and is called
the cupel. The vault of the furnace is formed by a sheet-iron
cover, G, which can be raised and lowered at will. When the
lead is melted, a strong blast of air is blown upon its surface
through the tuyères tt; the lead is thus converted into oxide,
which melts and, driven by the current of air, flows from the
cupel through a notch cut in its edge down to the level of the
molten metal, and which is gradually deepened as that level
becomes lowered. The silver, which is not oxidizable, becomes
concentrated in the cupel as the lead is eliminated; and when
the last portions of the latter metal become oxidized, the sur-
face of the silver is covered with only a thin layer of fused
litharge, which breaks up suddenly and displays the brilliant.
surface of the metal. This phenomenon, called brightening,
indicates the termination of the operation.
The oxide of lead formed first in the cupellation of work-
lead is called abstrich. It is black, and still contains a little
silver, as well as copper and antimony (Berthier). The oxide
which flows out after the abstrich is litharge.
Properties of Lead.-Lead is a bluish-white metal, having
a certain degree of lustre when its surface is freshly cut. It
is the softest and least tenacious of all the common metals. It
can easily be cut with a knife and scratched by the finger-nail.
It may readily be reduced to thin sheets, but is not easily drawn
into wire. Its density is 11.363 (H. Deville). It melts be-
tween 326 and 334°, and volatilizes at a white heat. It may
sometimes be obtained crystallized in regular octahedra by
allowing a large quantity of molten lead to cool slowly, and
decanting the still liquid portion.
The brilliant surface of lead tarnishes in the air. When
melted, it rapidly absorbs oxygen and becomes covered with a
pellicle of oxide, which is transformed by the prolonged action
of heat into a yellow powder, known as massicot.
On contact with acrated water, lead absorbs oxygen and car-
bon dioxide, and becomes covered with a thin layer of carbon-
This fact explains the presence of traces of lead in rain-
water which has been collected from lead gutters, or kept in
leaden reservoirs.
ate.
The presence of small quantities of sulphates and chlorides
in water prevents this oxidation of lead, so that the metal can
be used without danger for the distribution of most spring and
river waters.
LEAD MONOXIDE.
361
Lead is rapidly dissolved by concentrated and boiling hydro-
chloric acid. Dilute sulphuric acid does not attack it; the
boiling concentrated acid converts it into sulphate with evolu-
tion of sulphurous acid gas. Nitric acid attacks and dissolves
it at ordinary temperatures, disengaging red vapors and forming
lead nitrate.
Lead and its compounds are poisonous. Its effects on the
economy are especially manifested after the long-continued
absorption of very small quantities of the metal, of which the
accumulation in the system is made evident by various symp-
toms; the best known is lead colic or painter's colic. Plumbers,
glaziers of pottery, painters, color-grinders, and the workmen
employed in the manufacture of minium, or red lead, white
lead, etc., are exposed to this chronic poisoning. The soluble
sulphates are antidotes for acute cases of poisoning, and potas-
sium iodide causes the elimination of lead from the system in
chronic cases.
Uses of Lead. This metal is used for the manufacture of
shot, and pipes for the distribution of water and gas. When
reduced to sheets it is made into gutters, the coverings of roofs,
linings for troughs and reservoirs. Sheet-iron dipped into a
bath of melted lead retains a coating of that metal, and is called
leaded iron. Lead enters into the composition of type-metal,
plumber's solder, pewter, etc.
LEAD MONOXIDE,
Pbo
Massicot and litharge, of which the formation has been in-
dicated, constitute the monoxide of lead.
Massicot is a yellow, amorphous powder. Litharge occurs in
reddish-yellow, crystalline scales. It is rendered crystalline by
the fusion and cooling through which it passes. It is sometimes
met with in the form of rhombic octahedra (Mitscherlich).
Oxide of lead melts at a red heat; when fused it absorbs
oxygen, which it again gives up on solidifying (F. Le Blanc).
It cannot be melted in an earthen crucible without attacking
and sometimes piercing the latter, owing to the formation of a
very fusible silicate of lead.
Lead monoxide is easily reduced by hydrogen, charcoal, and
carbon monoxide.
It is very slightly soluble in water, and possesses a sufficiently
31
362
ELEMENTS OF MODERN CHEMISTRY.
marked alkaline reaction to restore the blue color to feebly
reddened litmus-paper.
When potassium hydrate or ammonia is added to a solution
of a salt of lead, a white precipitate, which is a hydrate of lead,
is formed. This hydrate dissolves in an excess of potassium
hydrate; it is also soluble in lime-water, and these solutions
are precipitated black by hydrogen sulphide.
Litharge is used for the manufacture of lead acetate and
white lead. It gives to linseed oil drying properties. It enters
into the composition of various plasters, and different coloring
matters (Cassel's yellow).
LEAD DIOXIDE.
PbO2
This body is made by treating minium, or intermediate oxide
of lead, with dilute nitric acid. A brown powder remains and
must be washed with boiling water. This is dioxide of lead;
it is insoluble in water; it is readily decomposed by heat, losing
half of its oxygen and being converted into monoxide. It is
an energetic oxidizing agent. When it is briskly triturated
with a small quantity of sulphur, the latter is inflamed.
If lead dioxide be introduced into a test-tube filled with sul-
phurous acid gas, the latter is immediately absorbed with for-
mation of lead sulphate.
SO² + PbO² = PbSO¹
Hydrochloric acid poured upon lead dioxide determines the
formation of lead chloride and the disengagement of chlorine.
PbO2 + 4HCI PbCl² + Cl2 + 2H2O
Lead dioxide unites with the alkalies forming veritable salts.
Fremy has described a plumbate of potassium, K²PbO³ +
3H20, which crystallizes in cubes, and which is formed when
dioxide of lead is gently heated with a very concentrated solu-
tion of potassium hydrate in a silver crucible.
PLUMBOSO-PLUMBIC OXIDE (RED LEAD)
This oxide is prepared by heating massicot in furnaces to a
temperature that should not exceed 300°. Under these con-
ditions, the monoxide absorbs oxygen from the air, and is con-
LEAD SULPHIDE.
363
verted into a beautiful red powder known as minium or red lead.
The product obtained by heating lead carbonate or white lead
in contact with the air is called orange minium.
Minium is a combination of monoxide and dioxide of lead;
its composition is variable, according to the length of time it
is roasted. It ordinarily corresponds to the formula
Pb³02PbO.PbO2 (Jacquelain)
Sometimes it contains less oxygen, having the composition
Pb¹O5 3PbO.PbO2 (Mulder)
Red crystals of the latter composition have been found in
the fissures of a minium furnace.
Minium has a scarlet-red color, which becomes much darker
on heating. It gives up oxygen at a red heat, being reduced
to monoxide. If red lead be sprinkled with nitric acid, the
color disappears, giving place to a brown. The nitric acid
removes the monoxide, forming nitrate, and leaves the brown
dioxide.
Minium is used to color sealing-wax and wall-papers. It is
employed in the manufacture of flint glass, which owes its fusi-
bility, its perfect transparency and its refractive power, to sili-
cate of lead. When mixed with stannic oxide, minium serves
as an enamel for crockery-ware.
A mixture of red lead and white lead with a small quantity
of oil is employed as a luting for steam-pipes, and as a cement.
LEAD SULPHIDE.
PbS
Galena or sulphide of lead occurs in nature in beautiful
cubical crystals of a bluish-gray color and a metallic lustre; its
density is 7.58. It melts at a red heat. When heated in con-
tact with air, it is converted into oxide and sulphate, and by the
reaction of an excess of sulphide upon these compounds me-
tallic lead is produced. Hot fuming nitric acid converts lead
sulphide into sulphate. Concentrated and boiling hydrochloric
acid transforms it into chloride with evolution of hydrogen
sulphide.
Galena is used for glazing common pottery. A broth of
powdered galena and cow's dung mixed with water is applied
to the surface of the previously well-dried vessels.
364
ELEMENTS OF MODERN CHEMISTRY.
This sort of pottery is generally baked at a temperature not
very high, so that the sulphide of lead, the oxidation of which
is prevented by the cow's dung, melts and spreads over the sur-
face, forming a varnish of a dark color when cold. Neverthe-
less, a small quantity of oxide is always formed by the oxidation
of the galena: when the baking takes place at a higher temper-
ature, this oxide forms a fusible silicate, which covers the
pottery. This glazing often has a green color, due to the
presence of oxide of copper, and is attacked by vinegar and
other acids, which dissolve the oxides of lead and copper.
Hence the danger in the use of ware so glazed for culinary
purposes.
LEAD CHLORIDE.
PbCl2
This body may be obtained as a white, crystalline powder by
heating litharge with hydrochloric acid. It is deposited as a
dense, white precipitate when hydrochloric acid is added to a
concentrated solution of acetate or nitrate of lead. It is not
very soluble in water; 135 parts of water at 12.5°, or 33 parts
of boiling water being required to dissolve one part of lead
chloride. It may be obtained crystallized in long needles by
allowing its saturated boiling solution to cool. Lead chloride
melts below a red heat, and on cooling solidifies to a semi-trans-
parent mass, known by the ancient chemists as horn-lead.
Mineral yellow, Turner's yellow, and Cassel's yellow, em-
ployed in painting, are oxychlorides of lead, combinations of
lead oxide and chloride in variable proportions.
LEAD IODIDE.
PbI2
When a solution of potassium iodide is added to a solution
of lead acetate, a beautiful yellow precipitate of lead iodide is
formed.
This body melts to a red-brown liquid at a high temperature.
It requires for solution 1235 parts of cold, or 194 parts of
boiling water. On the cooling of its saturated, boiling solution,
it is deposited in golden-yellow, hexagonal scales having a mag-
nificent lustre.
LEAD NITRATE-LEAD SULPHATE.
365
LEAD NITRATE.
Pb(NO3)2
This body is prepared by dissolving litharge in dilute nitric
acid. It crystallizes from its hot, saturated solution in anhy-
drous, white, regular octahedra. These crystals decrepitate.
when they are heated; they dissolve in 7½ times their weight
of cold water, and in a much less quantity of boiling water.
At a red heat this salt is decomposed into nitrogen peroxide,
oxygen, and lead monoxide. It forms various basic compounds
with lead monoxide.
When one molecule of the nitrate is boiled with one molecule
of the monoxide, and the filtered solution is allowed to cool,
a crystalline deposit is obtained, which is a dibasic nitrate,
Pb(ÑO³)² + Pb+ H2O (Pelouze). This salt can be consid
ered as derived from orthonitric acid, H³NO* HNO3 +
H2O. Indeed
Pb(NO3)2 + PbO + H2O = 2
Pb
}
NO¹
H
This basic nitrate of lead corresponds to the basic nitrate of
bismuth (page 351).
Bi""NO¹
Bismuth subnitrate.
Pb"? NO
H
Lead subnitrate.
When a solution of nitrate of lead is boiled with thin sheet-
lead, the latter is dissolved, and the liquid assumes a yellow
color. Under these conditions soluble basic nitrites of lead are
formed. On cooling the filtered liquid deposits yellow crystals.
having a variable composition. By a prolonged boiling a tetra-
basic nitrite, Pb(NO²)² + 3PbO + H2O, is obtained. The so-
lution of the latter, decomposed by carbon dioxide, gives the
neutral nitrite Pb(NO²)² + H2O, crystallizing in long, yellow
prisms (Peligot) or in yellow plates (Chevreul).
LEAD SULPHATE.
PbS04
This salt is found crystallized in nature. It can be prepared
by double decomposition by precipitating the solution of any
soluble lead salt, such as the nitrate or acetate, with sulphuric
acid or solution of a sulphate. It is a white powder, insoluble
in water.
31*
366
ELEMENTS OF MODERN CHEMISTRY.
At a high temperature, lead sulphate melts without decom-
position. Charcoal reduces it, transforming it into sulphide,
metal, or oxide, according to the proportions employed.
Quickly heated with an excess of charcoal, it yields sulphide.
PbSO¹ + C² = 2CO² + PbS
By diminishing the proportion of charcoal, a residue of
metal, or even of oxide, may be obtained.
PbSO+ + C
2PbSO¹ + C
CO² + SO² + Pb
CO² + 280² + 2PbO
Iron and zinc, in contact with lead sulphate suspended in
water, cause the separation of metallic lead.
LEAD CARBONATE.
РЬСО3
Crystallized lead carbonate is found in nature. The salt
may be obtained artificially, as an amorphous white powder, by
precipitating a soluble lead salt by an excess of an alkaline
carbonate.
A hydrated, and sometimes basic, carbonate of lead is known
as ceruse or white lead. Its composition varies.
PbCO3 + H2O and 2PbCO³ + Pb(OH)²
D
These are much used in oil painting. White lead is pre-
pared by several methods, the oldest of which is called the
Dutch process. It consists in exposing sheets of lead to an
atmosphere charged with acetic acid
vapor and rich in carbonic acid gas.
The leaden sheets are introduced
A into glazed earthen pots, A (Fig.
111), containing a small quantity of
vinegar. The lead rests upon short
projecting arms, B, below which is
placed the crude vinegar. The
pots are covered by a disk of lead,
D, which incompletely closes them.
They are then arranged in rows in
large chambers; a row of pots is
placed on a bed of spent tan or horse-manure; these are cov-
ered with planks, upon which more spent tan or horse-manure
is placed, and then another layer of pots, and so on. The fer-

FIG. 111.
LEAD CHROMATE.
367
mentation of the tan or manure raises the temperature to 30
or 40°, and produces carbonic acid gas. On the other hand,
the oxygen of the air intervenes, causing the lead to be
attacked by the acetic acid, so that basic acetate of lead is
formed upon the surface of the metal; but this salt is con-
tinually decomposed by the carbonic acid gas, so that the lead
gradually becomes covered with a layer of carbonate.
Thenard suggested another process by which litharge is dis-
solved in a solution of lead acetate, and a current of carbon
dioxide passed through the solution of subacetate so formed.
Lead carbonate is precipitated and neutral acetate regenerated;
the latter is then again transformed into basic acetate. The
product so obtained is known as Clichy white lead.
LEAD CHROMATE.
PbCrO
This salt exists crystallized in nature, constituting the red
lead of Siberia. It is prepared by double decomposition
between solutions of potassium chromate and lead acetate; a
yellow precipitate is thus obtained, and is employed in painting
under the name chrome yellow.
Lead chromate melts at a red heat; at a white heat it loses
4 per cent. of oxygen. It is easily reduced by charcoal and
hydrogen. Insoluble in water, it dissolves readily in solutions
of potassium hydrate.
Characters of Lead Salts.-The soluble lead salts have a
sweetish taste. Black precipitates are formed in their solutions
by both hydrogen sulphide and ammonium sulphide.
Potassa and soda yield white precipitates, soluble in a large
excess of the reagent. Ammonia gives a white precipitate,
insoluble in excess.
Sulphuric acid forms a white precipitate even in the most.
dilute solutions of lead. Hydrochloric acid forms a white
precipitate of lead chloride, but this precipitate is not produced
in dilute solutions.
Potassium chromate throws down a yellow precipitate, soluble
in potassium hydrate.
When heated with sodium carbonate upon a piece of charcoal
in the reducing flame of the blow-pipe, the lead salts yield a
metallic globule which when cold can readily be flattened out
by hammering.
368
ELEMENTS OF MODERN CHEMISTRY.
COPPER.
Cu(Cuprum)
= 63.5
Natural State.-Copper is found in the native state, some-
times crystallized in regular octahedra, sometimes in masses.
It is also found as cuprous oxide, Cu²O, cupric oxide, CuO, and
cupric carbonate, CuCO³; but its most abundant minerals are
cuprous sulphide, Cu'S (Chalkosine), and a double sulphide.
of copper and iron, Cu'S. Fe S3, designated as copper pyrites.
Under the name gray copper are also worked various minerals
containing cuprous sulphide combined with the sulphides of
antimony and arsenic, and in which the copper is sometimes
replaced by iron, zinc, silver, and mercury.
Treatment of Copper Ores.-Copper is easily extracted
from cuprous oxide and cupric carbonate.
These ores are
melted with charcoal in suitable furnaces, and the metal is at
once obtained. Copper pyrites, which is often mixed with
cuprous sulphide, requires a more complicated treatment. The
iron and sulphur must be eliminated, and for this reason the
ore is subjected to an incomplete roasting. This operation is
conducted in a reverberatory furnace (Fig. 112). The flame

BU BUFET, SILL
ي للسلك الشد من
utu
VULL
13
Cathe
C
FIG. 112.
ལ་འ་ མམ་
ミミミカ
​The
of the fire sweeps the arched vault of the furnace vv.
opening of the chimney is at C, and the ore is fed in from iron
troughs placed above the furnace.
COPPER.
369
The first roasting drives out part of the sulphur, and the
sulphides of iron and copper are partially converted into oxides
and sulphates. An excess of sulphide remains, and the im-
perfectly-roasted ore is fused in presence of silicious materials.
The scoriæ formed in roasting the matt (see farther on) are
generally added, and sometimes fluor spar, to render the slag
more fusible. This operation is conducted either in cupola-fur-
naces or in reverberatory furnaces of peculiar construction. In
presence of the unattacked sulphide of iron, the cupric oxide
formed during the roasting is converted into cupric sulphide, and
oxide of iron is formed. The latter unites with the silica, as
does also the oxide produced by the roasting, both being reduced
to ferrous oxide by the reducing gases of the fire. Ferrous sili-
cate is thus formed, and constitutes a very fusible slag, below
which accumulates the sulphide of copper containing much less
sulphide of iron than the original pyrites. This product is the
matt.
The sulphur, which was thus far necessary to expel the iron,
must now be removed, and the matt is broken up and repeat-
edly roasted, by which the remainder of the iron is oxidized and
nearly all of the sulphur expelled. The mineral is now again
melted with silicious materials and the scoria produced in re-
fining black copper, and rich in cupric oxide, are added. Ferrous
silicate separates as a slag, and a metallic mass containing from
90 to 94 per cent. of copper, still alloyed with iron, lead,
arsenic, sulphur, etc., is obtained. This product constitutes
black copper.
Refining of Black Copper.-The impure metal is melted in
a reverberatory furnace; the oxygen of the air transforms the
copper into oxide, and the latter is gradually reduced by the.
foreign metals and the sulphur still contained in the mass of
copper; these oxides separate in the form of scoriæ and slags,
which are removed. The liquid copper collects in a cylin-
drical cavity in the furnace, where it is solidified by throwing
cold water upon the surface of the molten metal; it is then
removed in the form of disks, and is called rosette copper.
The copper thus obtained is brittle, owing that property to the
cupric oxide with which it is still impregnated. It is finally
melted under a layer of charcoal, and stirred with poles of green.
wood.
Red, ductile copper is thus obtained.
At Mansfeld, in Prussia, a copper pyrites is worked which
Q*
370
ELEMENTS OF MODERN CHEMISTRY.
is disseminated in little crystals in an argillaceous schist impreg-
nated with bitumen. After a series of roastings and smeltings,
a black copper is obtained, rich enough in silver to permit of
the advantageous extraction of that metal.
For this purpose
the method called liquation is employed. The argentiferous
copper is melted with lead, and the liquid alloy is allowed to
cool slowly. Copper solidifies first, alloyed with a small quan-
tity of lead, while the remainder of the lead, retaining nearly
all of the silver, remains liquid. By another process the alloy
of lead and argentiferous copper is made into disks, D (Fig. 113),
and these are reheated very slowly.
As soon as the temperature is suf-
ficiently high, the lead melts and
runs out, carrying with it all of the
silver. The copper remains al-
loyed with a small quantity of lead.
It is refined by melting it in a cu-
pola-furnace under the blast of a
tuyère. The lead and iron and
part of the copper are oxidized,
and the oxides are removed as scoriæ. Pure copper remains
and is converted into rosette. The argentiferous lead is sub-
mitted to cupellation, as already described.

THELL
FIG. 113.
րերը կին
Cement copper is copper precipitated from a solution of
cupric sulphate by metallic iron. It is very pure.
Properties of Copper. This metal has a characteristic red
color that is universally known. When rubbed with the hand
it exhales a peculiar, disagreeable odor. By fusion it crystal-
lizes in cubes, but it may be deposited by electrolysis in reg-
ular octahedra. It melts towards 1100°, and may be volatilized
by the heat of the oxy-hydrogen blow-pipe.
Its density varies from 8.85 to 8.95. It is very malleable,
ductile, and tenacious.
In dry air it is unaltered at ordinary temperatures, but it
absorbs oxygen in presence of moisture and carbonic acid gas.
Green spots are then formed upon the surface of the metal,
constituting a hydrocarbonate of copper; this is the product
ordinarily called verdigris.
At a high temperature copper absorbs oxygen with avidity,
being converted into black, cupric oxide if the oxygen be in
excess; but in the contrary case, red, cuprous oxide is formed.
The oxidation is favored by division of the metal.
CUPROUS OXIDE.
371
If some pulverulent copper, produced by the decomposition
of copper acetate, be thrown upon a moderately hot tile and an
incandescent coal be approached so as to heat one point, a black
spot instantly forms there and rapidly extends throughout the
mass, showing the progress of the oxidation.
In presence of acids or ammonia, copper rapidly absorbs.
oxygen at ordinary temperatures.
If some ammonia and copper-turnings be shaken up with air
in a glass-stoppered bottle, the ammoniacal liquid becomes blue;
if now the bottle be turned upside-down and opened under
water, the latter will rise in the bottle, replacing the oxygen
which was absorbed. The blue liquid contains in solution am-
moniacal oxide of copper and nitrite of copper (Schönbein,
Peligot).
This liquid is capable of dissolving cotton and lint, which
are almost pure cellulose (Schweizer).
When heated with concentrated sulphuric acid, copper is
converted into sulphate with disengagement of sulphurous
acid gas. Nitric acid, even dilute, dissolves it readily, forming
cupric nitrate and evolving nitrogen dioxide. Boiling hydro-
chloric acid attacks it slowly, disengaging hydrogen and forming
cuprous chloride.
Uses of Copper.-Copper is much employed for the con-
struction of boilers, alembies, stills and worms, and for kitchen
utensils. Sheet-copper is used for coating the bottoms of ships
and sometimes for roofing houses. This metal enters into the
composition of the more important alloys, brass (copper and
zinc), bronze (copper and tin), German silver (copper, zinc, and
nickel).
CUPROUS OXIDE.
Cu2O
This oxide is found in nature, sometimes in vitreous masses,
sometimes in beautiful, red, regular octahedra.
It is ordinarily prepared in the wet way by boiling a solution
of acetate of copper with glucose; a bright-red, crystalline pow-
der is precipitated, which is anhydrous cuprous oxide. When
heated in contact with air, it absorbs oxygen and is converted
into cupric oxide.
When potassium hydrate is added to a solution of cuprous
chloride, a yellow precipitate of cuprous hydrate is thrown
down. Cuprous oxide is used to communicate a red color to glass.
372
ELEMENTS OF MODERN CHEMISTRY.
CUPRIC OXIDE.
CuO
Two processes are used for the preparation of this important
body: calcination of copper in the air; calcination of cupric
nitrate. The first method furnishes a granular, compact, black
oxide; the second, a fine, deep-black powder.
Cupric oxide is easily reduced by both hydrogen and char-
coal, with formation of either water or carbon dioxide.
With water it forms a hydrate, Cu(OH)² = CuO.H2O, which
precipitates as a thick, light-blue magma, when potassium hy-
drate is added to a cupric solution. This hydrate is converted
into brown, anhydrous oxide by boiling with water. Cupric
oxide is largely used in the laboratory in the analysis of or-
ganic substances. It is used in the arts to color glass, to which
it imparts a green color.
SULPHIDES OF COPPER.
Copper forms two sulphides, corresponding to the oxides.
Cuprous sulphide, Cu'S, occurs in nature in fusible, steel-gray
crystals, which may be scratched with a knife.
Cupric sulphide CuS, is formed in the wet way when a
solution of a copper salt is precipitated by hydrogen sulphide.
When strongly calcined, it loses sulphur and is reduced to
cuprous sulphide.
If copper filings or turnings be thrown into a flask containing
boiling sulphur, a brilliant incandescence takes place from the
union of the two elements.
CHLORIDES OF COPPER.
Cuprous chloride, Cu Cl, is prepared by boiling copper-
turnings in hydrochloric acid and adding small quantities of
nitric acid from time to time. The nitro-muriatic acid formed
converts the copper into cupric chloride, which is reduced by
the excess of copper present. A brown liquid is thus obtained
which, by continued boiling, becomes almost colorless. On
adding water to this liquid, a white, crystalline precipitate of
cuprous chloride is deposited. It is insoluble in water, but dis-
solves in aqueous ammonia, forming a liquid which remains
colorless when kept in closed vessels in presence of an excess
CUPRIC SULPHATE.
373
of copper, but becomes blue on exposure to the air, from which
it absorbs oxygen.
Carbon monoxide is perfectly absorbed by a solution of
cuprous chloride in hydrochloric acid or in ammonia.
Cupric chloride, CuCl, is obtained by dissolving cupric oxide
in hydrochloric acid or in aqua regia. A green solution is
formed, which, after concentration, deposits beautiful rhombic
prisms of a bluish-green color, containing 2 molecules of water
of crystallization.
CUPRIC SULPHATE.
CuSO4 + 5H²O
Preparation. This salt is commonly called blue vitriol. It
is a product of many industrial operations, such as roasting
sulphurous copper ores, and the decomposition by copper of
the silver sulphate resulting from the refining of gold,-that
is, the treatment of silver coin containing gold with sulphuric
acid.
Cupric sulphate produced by roasting copper ore contains
more or less ferrous sulphate. The two salts crystallize together
in oblique rhombic prisms, containing 7 molecules of water of
crystallization. The mixture is called Salzburg vitriol.
Instead of copper pyrites, artificial cupric sulphide may be
oxidized. Old copper plates are moistened and sprinkled with
flowers of sulphur; they are then heated in a furnace, and the
sulphide of copper first formed is converted into sulphate hy
the oxygen of the air drawn into the furnace. The still hot
plates are plunged into water, which dissolves the layer of cupric
sulphate, and the same operation is repeated until all of the
metal is transformed into sulphate.
The simplest process consists in boiling copper turnings and
clippings with sulphuric acid: sulphurous acid gas is disen-
gaged, and cupric sulphate formed. In the arts, the operation
is conducted in wooden tanks lined with lead and heated by
steam.
Properties. Cupric sulphate crystallizes in parallelopipedons
belonging to the type of the dissymetric prism. These crystals
have a fine blue color, and contain 5 molecules of water. When
exposed to dry air they effloresce superficially: heated to 100°,
they lose molecules of water, disengaging the fifth only at
243°. The anhydrous salt is white. At a high heat, cupric
32
374
ELEMENTS OF MODERN CHEMISTRY.
sulphate is decomposed into cupric oxide, sulphurous oxide,
and oxygen.
Cupric sulphate dissolves in 4 parts of cold, and in 2 parts
of boiling water, and the concentrated solution has a pure blue
color. It is insoluble in alcohol.
When an excess of ammonia is added to a solution of cupric
sulphate, a beautiful, dark-blue liquid is obtained. It contains
ammoniacal cupric sulphate, CuSÔ¹ + 4NH³ + H2O, which
separates in dark-blue crystals when alcohol is added to the
aqueous solution.
There are several basic sulphates of copper representing
compounds of cupric sulphate and cupric hydrate. One of
them is obtained as a green powder when a solution of cupric
sulphate is digested with cupric hydrate. The bluish precipi-
tates obtained by incompletely precipitating solutions of cupric
sulphate with potassium hydrate are basic sulphates.
Uses.-Cupric sulphate is employed as a caustic applicable
to diseases of the eye. In the arts, it is used in the prepara-
tion of blue ashes, a mixture of calcium sulphate and cupric
hydrate, made by decomposing cupric sulphate with milk of
lime.
It is much used in dyeing, particularly in dyeing black on
wool and cotton. Its solution is used for steeping wheat.
Large quantities of sulphate of copper are employed for elec-
trotyping.
CARBONATES OF COPPER.
When cold solutions of sodium carbonate and cupric sul-
phate are mixed, a bluish-green precipitate is obtained, and at
the same time carbonic acid gas is disengaged. The precipi-
tate becomes green when washed with warm water. It is
known as mineral green, and can be regarded as a combina-
tion of one molecule of cupric carbonate with one molecule of
cupric hydrate. It contains
CuCO + Cu(OH)2
A similar compound exists in nature, constituting malachite.
This mineral occurs in green masses. When cut and polished,
it presents veins of various tints, and is fashioned into orna-
mental objects, such as vases, cups, etc.
Azurite or mountain blue, which crystallizes in beautiful,
CARBONATES OF COPPER.
375
blue, oblique rhombic prisms, can be regarded as a compound
of two molecules of cupric carbonate with one of the hydrate.
2CuCO³+ Cu(OH)2
Debray has reproduced azurite artificially by leaving calcium
carbonate for a long time in contact with cupric nitrate in
sealed tubes.
ALLOYS OF COPPER.
Brass is an alloy of copper and zinc, ordinarily containing
zinc and copper. It often contains a small proportion of tin
and even of lead.
Bronze is an alloy of copper and tin (see table of alloys, page
237). While brass is malleable and ductile, bronze is brittle
when it has been slowly cooled, but it becomes malleable after
tempering, that is, when it is heated to redness and then
plunged into cold water.
German silver contains 25 per cent. of zinc, 25 of nickel,
and 50 of copper.
Characters of Copper Salts.-These salts are blue or green.
Their solutions are precipitated brown by hydrogen sulphide
and ammonium sulphide; an excess of the latter reagent will
not dissolve the precipitate.
Potassium hydrate forms a dense, light-blue precipitate, in-
soluble in excess. Ammonia first forms a pale-blue precipitate,
which is then dissolved by an excess of the reagent with a rich
sky-blue color.
Potassium ferrocyanide gives a chestnut-brown precipitate
even in very dilute cupric solutions.
An apple-green precipitate of cupric arsenite (Scheele's
green) is formed when potassium arsenite is added to cupric
sulphate.
A bright piece of iron plunged into a cupric solution in-
stantly becomes covered with a deposit of metallic copper.
MERCURY.
Hg (Hydrargyrum)
= 200
Natural State and Extraction.-Mercury occurs native,
and especially combined with sulphur, mercuric sulphide or
natural cinnabar being its principal ore. It is found in differ-
376
ELEMENTS OF MODERN CHEMISTRY.
ent localities in Europe and America, principally at Almaden,
Spain; Idria, in Illyria; San José, in California.
The treatment of the ore is very simple. The sulphide is
roasted in a current of air in furnaces of peculiar construction :
the sulphur is oxidized, and passes off as sulphur dioxide, the
mercury being set free. The metal volatilizes and is led, to-
gether with the gases from the combustion, either into con-
densation-chambers, or through long rows of little cylindrical
vessels, where the mercury condenses.
Fig. 114 represents the furnaces employed at Almaden,
with the fireplace, and the body, AB, charged with ore.
The

10
d
d
FIG. 114.
mercury-vapor passes by o, and condenses in a series of aludels
entering one in the other, and arranged upon two inclined planes,
ab, bc.
The condensed metal runs into a channel, b, from
which it is conducted into a reservoir. The sulphurous acid
gas, still charged with vapor of mercury, passes into a chamber,
C, descending to the floor, where it is cooled by contact with a
trough filled with water, d. In this chamber the condensation
of the mercury-vapor is completed.
Fig. 115 represents the several-storied furnaces aa, bb, cc,
and the condensation-chambers CC, used at Idria.
Cinnabar may also be reduced by iron or by lime.
The metal thus extracted is purified by filtration through
ticking-cloth or chamois-skin. It is ordinarily transported in
forged iron bottles.
The mercury of commerce is nearly always alloyed with small
quantities of other metals, such as lead, tin, copper, and bis-
MERCURY.
377
muth. In this state its surface is not as brilliant as when pure,
it does not run as readily, and the drops are drawn out to a
point. They are said to form tails. It may be purified by dis-
tillation, an operation which requires certain precautions, and
which is ordinarily effected in the iron bottles which serve for
the transportation of the metal.
It may also be purified by digesting it for several days with
one-thirtieth its weight of commercial nitric acid diluted with
its own weight of water; the aqueous liquid is then decanted
and the mercury washed, first with warm water acidulated with
nitric acid, then with pure water, after which it can be dried.
In this operation, the nitric acid removes the foreign metals,
more oxidizable than the mercury, which displace the latter
metal from its solution in the nitric acid.

FIG. 115.
Properties. Mercury is liquid, but solidifies at -10°. The
Properties.—Mercury
solid metal at this low temperature is malleable, and has a
density of 14.4. The density of liquid mercury is 13.595. It
boils at 350° of an air thermometer. Its vapor is colorless,
and has a density of 6.976.
It is unaltered by contact with the air at ordinary tempera-
tures, but at 300° it slowly absorbs oxygen, and its surface
becomes covered with a red powder, which is mercuric oxide,
called by the ancients red precipitate.
Mercury combines with chlorine, bromine, and iodine at ordi-
nary temperatures, and with sulphur by the aid of a gentle heat.
32*
378
ELEMENTS OF MODERN CHEMISTRY.
Hydrochloric acid does not attack it. Dilute nitric acid dis-
solves it in the cold, forming mercurous nitrate. Hot nitric
acid dissolves it, forming mercuric nitrate and evolving red
vapors.
OXIDES OF MERCURY.
Two oxides of mercury are known, mercurous oxide, Hg2O,
and mercuric oxide, HgÓ.
The first is prepared by digesting mercurous chloride (calo-
mel) with potassium hydrate; a black powder is obtained which
very unstable. By the action of light, or by a temperature
above 100°, it decomposes into mercuric oxide and mercury.
is
Mercuric Oxide, HgO, can be obtained by either the dry or
wet method. The first consists in decomposing mercuric nitrate
by heat; the salt is gradually heated in a flask on a sand-
bath until red vapors cease to be disengaged.
The oxide thus prepared is an orange-red, granular, and
crystalline powder.
Mercuric oxide is prepared in the wet way by decomposing
a solution of mercuric chloride by potassium hydrate. A
yellow precipitate of anhydrous mercuric oxide is obtained.
When mercuric oxide is heated, it assumes a dark-red color
and decomposes, if the temperature be above 400°, into oxygen
and mercury. It yields its oxygen to many bodies, such as
charcoal, sulphur, and phosphorus, which it oxidizes energet-
ically. When heated with sulphur, it produces an explosion.
In these reactions the finely-divided yellow oxide is more active
than the red oxide.
MERCURIC SULPHIDE.
HgS
This is the cinnabar generally found in nature in compact
masses, sometimes in transparent, red, hexagonal prisms or
rhombohedra. It is manufactured by directly combining sul-
phur and mercury. The combination takes place when the
bodies are triturated together in the cold, in the proportion of
100 parts of mercury and 18 parts of sulphur. A black mass
is thus obtained which is sublimed in iron vessels.
Cinnabar prepared by sublimation occurs in dark-red masses,
having a fibrous and crystalline structure. Its density is 8.124.
At a high temperature, it volatilizes without melting. When
MERCUROUS CHLORIDE.
379
heated in the air, it burns with a blue flame, yielding sulphur-
ous acid gas and metallic mercury. It is decomposed by hydro-
gen, charcoal, and most of the metals. Boiling sulphuric acid
decomposes it with formation of sulphurous acid gas and sul-
phate of mercury. Nitric acid scarcely attacks it, even when
boiling.
Vermillion is a finely-divided mercuric sulphide having a
rich scarlet color. It is prepared by triturating for several
hours in a mortar, 300 parts of mercury and 114 parts of
flowers of sulphur, and adding to the black sulphide thus ob-
tained 75 parts of potassa and 100 parts of water. The mixture
is maintained at a temperature of about 45°, being continually
triturated with a pestle. As soon as the powder has acquired
a fine scarlet color, it is rapidly washed with hot water and
dried. It is employed in painting and also to color sealing-
wax.
MERCUROUS CHLORIDE, OR CALOMEL.
Hg2C12
Mercurous chloride is largely used in medicine under the
name calomel or mild chloride of mercury.
Preparation. An intimate mixture of mercurous sulphate
and sodium chloride is heated in a capacious glass matrass on
a sand-bath. The mercurous chloride, formed by double decom-
position, sublimes.
Hg2SO4 + 2NaCl
Hg²Cl² + Na2SO¹
When
It is thus obtained in compact, crystalline masses.
it is strongly heated and its vapor passed into large stoneware
vessels filled with steam, it condenses in an impalpable powder,
in which form it is used by preference in medicine.
Calomel may also be prepared in the wet way by adding
hydrochloric acid, or a solution of sodium chloride, to a solu-
tion of mercurous nitrate. A white, curdy precipitate is
obtained which is washed and dried.
Properties. Prepared in the dry way calomel occurs as
dense, fibrous, crystalline and slightly transparent masses, one
side of which is smooth, the other presenting the sharp points
of the crystals. When exposed to light, it becomes yellow and
even gray in time, being partially decomposed. Its density is
380
ELEMENTS OF MODERN CHEMISTRY.
7.17. The density of its vapor is 8.35.
8.35. It melts and vola-
tilizes at the same temperature. When slowly sublimed, it
crystallizes in square prisms. It is insoluble in water.
A solution of potassium iodide agitated with calomel con-
verts it into a green powder of mercurous iodide. If an excess
of potassium iodide be employed, the green powder disappears
and is replaced by a gray precipitate of metallic mercury, the
mercurous iodide at first formed being decomposed into mercury
and mercuric iodide, which dissolves in the potassium iodide.
An analogous reaction takes place with the alkaline chlorides
by the aid of heat, the mercurous chloride breaking up into
mercuric chloride which dissolves, and metallic mercury which
is deposited.
MERCURIC CHLORIDE, OR CORROSIVE SUBLI-
MATE.
HgCl2
Preparation. This body is obtained by double decomposi-
tion, by heating a mixture of mercuric sulphate and sodium
chloride on a sand-bath. The mercuric chloride condenses in
the upper part of the matrasses which are imbedded up to the
neck in the sand.
HgSO2NaCl Na'SO + HgCl2
Towards the close of the operation the heat is increased in
order to agglomerate the sublimate by a partial fusion.
Another process consists in passing chlorine into heated
mercury; the combination takes place with the production of
luminous heat.
Properties. Mercuric chloride prepared by the dry method
occurs in compact, white, crystalline and friable masses, having
a density of 6.5. It is an energetic poison. It melts at about
265°, and boils towards 295°. The density of its vapor is
9.42. By sublimation it may be obtained crystallized in rec-
tangular octahedra.
It is soluble in 19 parts of cold water, also in alcohol and ether.
It is deposited from its hot, saturated, aqueous solution in
long prisms, belonging to the type of the right rhombic prism.
The crystals are anhydrous.
The aqueous solution of mercuric chloride produces a white
precipitate in a solution of albumen of white of egg. This
MERCUROUS IODIDE-MERCURIC IODIDE.
381
precipitate is a combination of mercuric chloride and albumen.
Albumen is thus the antidote to corrosive sublimate.
When a slight excess of ammonia is added to a solution of
corrosive sublimate, a white deposit is formed, known as white
precipitate, of which the composition is expressed by the
formula IIgH'NCI.
HgCl2 + 2NH³ = NH'Cl + HgH³NCI
It may be regarded as the chloride of mercury-ammonium,
that is, ammonium chloride in which 2 atoms of hydrogen are
replaced by one atom of the diatomic metal mercury.
Ho"
HgH¹NCI H
H
=
NCI
Corrosive sublimate forms crystallizable double combinations
with the alkaline chlorides and with ammonium chloride.
MERCUROUS IODIDE.
Hg212
This compound is ordinarily prepared by directly combining
mercury and iodine. 100 parts of mercury and 63.5 parts of
iodine are triturated with a small quantity of alcohol, until the
whole is converted into a green powder, which is then washed
with boiling alcohol and dried.
It may also be prepared by double decomposition by precipi-
tating a solution of mercurous nitrate with potassium iodide,
or by the reaction of the latter body upon calomel.
Mercurous iodide is not a stable compound. It is decom-
posed by light. Heat breaks it up into mercury and mercuric
iodide, and the same decomposition is effected by potassium
iodide and the alkaline chlorides.
MERCURIC IODIDE.
HgI2
Mercuric iodide is prepared by pouring a solution of 100
parts of potassium iodide into a solution of 80 parts of corro-
sive sublimate. A beautiful scarlet-red precipitate of mercuric
iodide is thrown down.
It is necessary that the bodies be employed in the propor-
382
ELEMENTS OF MODERN CHEMISTRY.
tions indicated; an excess of potassium iodide would dissolve
the mercuric iodide first precipitated.
Mercuric iodide is almost insoluble in water; it is slightly
soluble in boiling alcohol, which deposits it on cooling in small
red octahedral crystals.
If mercuric iodide be heated in a small glass retort, it melts
to a dark-yellow liquid which solidifies on cooling to a yellow
mass. At a higher temperature the liquid boils and its vapor
condenses in a dark-yellow liquid which solidifies to a yellow
mass; at the same time, right rhombic prisms of a yellow color
sublime. If these be rubbed with a glass rod or other hard
body they instantly become red, first at the point of contact,
then throughout the entire mass.
These two forms of mercuric iodide constitute one of the
most curious examples of dimorphism.
Mercuric iodide forms a combination with potassium iodide
which is soluble in water. A solution of this iodo-hydrargyrate
of potassium is not precipitated by potassium hydrate, but the
liquid rendered alkaline by the latter reagent is a very sensi-
tive test for ammonia ( Nessler's test), with which it gives a pre-
cipitate or a brown cloud more or less intense, according to the
quantity of ammonia present.
NITRATES OF MERCURY.
Neutral mercurous nitrate (Hg²)"(NO³)² + 2H2O, is ob-
tained by the action of an excess of cold, dilute nitric acid upon
metallic mercury. After some time, short colorless prisms are
formed in the liquid, constituting the neutral salt. The latter
is readily soluble in water charged with nitric acid.
When mercury is attacked by an excess of boiling nitric
acid and the solution is evaporated, voluminous crystals of a
basic mercuric nitrate separate, Hg(NO3)2.HgO + 2H2O.
The syrupy liquid from which these crystals are deposited,
contains neutral mercuric nitrate.
Hg(NO3)2 + 8H2O
This salt is deposited in large, colorless, rhombic tables when
the syrupy solution is cooled to -15°.
A large quantity of cold water decomposes this nitrate into
nitric acid which dissolves, and a basic salt, Hg(NO3)2.2HgO
+ H2O, forming a yellow powder.
SULPHATES OF MERCURY.
383
SULPHATES OF MERCURY.
There is a mercurous sulphate, (Hg²)"SO¹, and a mercuric
sulphate, Hg"SO¹.
The first is obtained by heating equal parts of mercury and
sulphuric acid, arresting the operation when two-thirds of the
mercury are converted into a white, crystalline powder. Mer-
curous sulphate is but slightly soluble in cold water.
To prepare mercuric sulphate, 1 part of mercury and 1½
parts of sulphuric acid are heated to complete desiccation on a
sand-bath.
Hg + 2H2SO = 2H2O + HgSO¹ + SO²
It is well to add a small quantity of nitric acid before drying.
Mercuric sulphate is an anhydrous, white powder. It decom-
poses at a red heat into metallic mercury, sulphurous acid gas,
and oxygen. Charcoal reduces it readily, equal volumes of
carbon dioxide and sulphur dioxide being disengaged.
Mercuric sulphate is slightly soluble in water: a large quan-
tity of cold water converts it into a yellow, basic salt, HgSO¹.
2HgO, known as turpeth mineral.
Characters of Mercurous Salts.-Their solutions are pre-
cipitated black by hydrogen sulphide, and also by potassium
hydrate and ammonia. Hydrochloric acid gives a white pre-
cipitate which is blackened by ammonia. Potassium iodide
forms a green precipitate of mercurous iodide, converted by
an excess of the reagent into mercuric iodide which dissolves,
and gray metallic mercury.
Characters of Mercuric Salts.-Solutions of mercuric salts
are precipitated black by an excess of hydrogen sulphide, and
by ammonium sulphide.
Potassium hydrate forms a yellow precipitate, insoluble in
excess.
Ammonia yields a white precipitate in solutions of corrosive
sublimate.
Hydrochloric acid does not precipitate the mercuric salts.
Iron, zine, and copper precipitate metallic mercury from
both mercurous and mercuric solutions. A slip of copper
dipped into such solutions becomes covered with a gray coating
which acquires brilliancy by rubbing.
Heated with lime in a glass tube, all of the mercury com-
pounds yield metallic mercury which sublimes in small globules,
384
ELEMENTS OF MODERN CHEMISTRY.
easy to recognize under the microscope, and which can be char-
acterized by the addition of iodine, the vapor of which converts
the metallic globules into yellow or red mercuric iodide.
SILVER.
Ag(Argentum) = 108
Natural State.-Silver is found native and in combination
in many minerals. Among these are the sulphide, the sulph-
antimonides and sulpharsenides, the antimonide, chloride, bro-
mide, iodide, selenide, telluride, and lastly an amalgam of
silver. It is found in small proportions in many galenas and
copper pyrites.
Treatment of Silver Ores.-The silver is extracted from
galena by first reducing the lead, and then submitting the
argentiferous lead obtained to cupellation (page 359).
Silver ores free from lead are treated by a peculiar process
called amalgamation, since it is based upon the employment
of metallic mercury which dissolves silver; the amalgam of
silver formed is decomposed by heat.
Several processes are employed for the chlorination and
amalgamation of silver.
Freiberg Amalgamation Process.-The Freiberg silver ore
is poor, containing only two or three thousandths of silver in
田
​'היד
the form of sulphide, disseminated
through iron and copper pyrites.
The ore is pulverized, mixed with
one-tenth its weight of common
salt, and roasted in a reverberatory
furnace. The sulphides are oxi-
dized, with disengagement of sul-
phurous acid gas and formation of
sulphates. The latter react upon the
sodium chloride, forming sodium
sulphate and metallic chlorides: all
of the silver is thus converted into
chloride. The product of the roast-
ing is reduced to powder, washed,
and introduced, together with water and scrap-iron, into amal-
gamation barrels, which are rotated by water-power (Fig. 116).
When the mixture has become homogeneous, mercury is added

FIG. 116.
و
SILVER.
385
and dissolves the silver set free by the action of the iron upon
the silver chloride; it also dissolves a small quantity of copper
formed by the reduction of cuprous chloride present. After
the barrels have been rotated for some hours, the amalgam is
collected and compressed in canvas bags, through which the
excess of mercury, alloyed with a very small quantity of
foreign metals, passes, while a pasty
amalgam of silver and copper remains
in the bags. This amalgam is put into
iron cups, bb (Fig. 117), set upon an
iron rod on a tripod base, a, standing in
a vessel of water. The whole is cov-
ered with a bell-shaped iron hood which
dips into the water, and the upper part
of which is surrounded by burning
coals. The mercury volatilizes and
condenses in the cold water, and an
alloy of silver and copper, containing
about 28 per cent. of the latter metal,
as well as small quantities of lead,
antimony, etc., remains in the cups.

پرست
FIG. 117.
It is purified either by cupellation or by refining.
Cupellation consists in melting the impure silver with lead,
as has been already described. In refining, the silver is melted
in a hemispherical iron vessel lined with a thick layer of marl
and wood ashes. It is a porous cupel, which absorbs the oxides
formed by the action of the air upon the lead and copper
alloyed with the silver; the latter remains in the cupel at the
close of the operation in a pure state.
Mexican Amalgamation Process.-American silver ore con-
sists of sulpharsenide and sulphantimonide of silver, mixed with
silver chloride and native silver, the whole being disseminated
in silica, calcium carbonate, and ferric oxide. In Mexico, the
following primitive process is still used. The finely-pulverized
ore is mixed with two per cent. of common salt and thrown
into circular areas paved with flag-stones, where it is rendered
homogeneous by being trodden for several hours by mules.
About one per cent. of copper pyrites which has been roasted
in the air and contains cupric sulphate is then added. The
latter salt reacts with the sodium chloride, forming sodium sul-
phate and cupric chloride, which latter decomposes the silver
sulphide, forming silver chloride and cupric sulphide. Mer-
R
33
386
ELEMENTS OF MODERN CHEMISTRY.
cury is then added and reduces the silver chloride, with for-
mation of chloride of mercury and metallic silver. During the
whole time the mass is continually trodden by the mules, and
the mercury comes in contact with the disseminated silver: the
amalgam formed solidifies in about a fortnight. A second and
finally a third addition of mercury is then made until 7 or 8
parts of that metal have been employed for one part of silver
to be extracted. After a few months, the operation is termi-
nated, and the mass is washed with large quantities of water to
remove the earthy and salty matters. The amalgam remains,
and is heated in order to extract the silver.
American Process.-The above method of extraction is too
slow to be employed for the vast quantities of silver ore that
are mined on the Pacific Slope. The ore is there crushed and
roasted with sodium chloride and a small proportion of cupric
sulphate, in furnaces of a peculiar construction. By this means
all of the silver is converted into chloride. The mass is made
into a pulp with water and agitated with mercury in large tanks
or vats. The silver chloride is reduced as before, and the
amalgam obtained is first squeezed out and afterwards heated
in iron retorts to expel the mercury.
Properties.-Silver is the whitest and most brilliant of all
the ordinary metals. Next to gold, it is the most malleable
and the most ductile. Its density is 10.5.
It melts towards 1000°, and when fused has the curious
property of dissolving oxygen, of which it absorbs 22 times its
volume. On solidifying, it again disengages the gas; this phe-
nomenon, which occasionally causes the projection of portions
of silver, is called spitting. Silver volatilizes at the high tem-
perature of the oxyhydrogen blow-pipe.
It is unaltered by the air. It absorbs ozone, being converted
into the dioxide Ag2O2. It combines with hydrogen dioxide,
forming argentous and argentic hydrates (Weltzien).
It decomposes concentrated solution of hydriodic acid, dis-
engaging hydrogen and forming silver iodide (Deville). Hy-
drochloric acid only attacks it superficially. Hydrogen sulphide
blackens it, forming a pellicle of silver sulphide. Its best sol-
vent is nitric acid which attacks it in the cold, yielding silver
nitrate and disengaging red vapors.
The alkalies have no action upon silver; for this reason, silver
vessels are used for fusing potassium hydrate and concentrating
its solution.
SILVER SULPHIDE-SILVER CHLORIDE.
387
SILVER OXIDE.
Ag20
The only important oxide of silver is the monoxide, which
is precipitated in the anhydrous state when potassium hydrate,
free from chloride, is added to a solution of silver nitrate.
It forms an olive-brown, flocculent deposit which yields a
brown powder on drying.
Silver oxide is readily decomposed by heat into silver and
oxygen. It is reduced by hydrogen at a temperature below
100°. When recently precipitated, it is slightly soluble in
water. It is an energetic base, perfectly neutralizing the acids,
and displacing cupric oxide from the cupric salts.
When oxide of silver is digested with ammonia it is con-
verted into a very explosive, black powder, known as fulmi-
nating silver. Its composition is not yet well known.
SILVER SULPHIDE.
Ag2S
To the oxide of silver corresponds the sulphide Ag²S, which
occurs native, crystallized in regular octahedra, ordinarily mod-
ified by facettes. It is soft and can be scratched by the finger-
nail. Silver and sulphur also combine readily by the aid of
heat.
SILVER CHLORIDE.
AgCl
This body is found native and is known to mineralogists as
horn-silver. It is sometimes found crystallized in cubes and
octahedra. It is formed directly when silver is heated in chlo-
rine gas, and is prepared by double decomposition by adding
hydrochloric acid or a solution of sodium chloride to solution
of nitrate of silver. A white, curdy precipitate is thus obtained,
which assumes a violet tint when exposed to the action of light.
The change of color is due to partial decomposition.
Silver chloride melts at about 260°, and solidifies on cooling
to a gray, horn-like mass that can be cut with a knife.
If recently precipitated and moist silver chloride be placed
upon a sheet of zinc, in a short time a dark color will appear
on the borders of the chloride, and the whole of that body will
388
ELEMENTS OF MODERN CHEMISTRY.
soon be converted into a dark-gray powder of finely-divided
silver. Zinc chloride is at the same time formed.
This reaction takes place much more rapidly if the silver
chloride be moistened with hydrochloric acid. In this case
the reduction is effected by nascent hydrogen produced by the
action of the hydrochloric acid on the zinc.
When silver chloride is fused with the alkaline hydrates or
carbonates, it is reduced to metallic silver: oxygen is disen-
gaged, and an alkaline chloride is formed.
Recently-precipitated silver chloride dissolves readily in aque-
ous ammonia. When dry, it absorbs ammonia gas abundantly,
and Faraday employed this compound for the preparation of
liquid ammonia.
Silver chloride dissolves also in solutions of the alkaline
hyposulphites.
SILVER IODIDE.
AgI
Silver iodide is obtained as a yellow precipitate by adding
potassium iodide to a solution of silver nitrate. It blackens
on exposure to light. It is but very slightly soluble in ammo-
nia, a property which distinguishes it from silver chloride.
SILVER NITRATE.
AgNO3
This salt is prepared by dissolving silver in nitric acid. If
the metal be pure, a colorless solution is obtained which after
concentration and cooling deposits large, colorless tables of an-
hydrous silver nitrate. If silver coin be employed, the solution
will be blue, containing, independently of silver nitrate, cupric
nitrate. The latter may be removed by evaporating the residue
to dryness and carefully heating it, so that the salt may remain
fused for some time. The cupric nitrate is decomposed, while
the silver nitrate remains mixed with cupric oxide, from which
it may be freed by solution and filtration.
Fused silver nitrate constitutes lunar caustic.
This salt dissolves in its own weight of cold, and in half its
weight of boiling water. The solution is neutral to test-paper.
When exposed to the air, it blackens, as do also the crystals
and the fused salt, by reason of a partial reduction due to the
organic matters suspended in the air.
ASSAYING OF SILVER.
389
It blackens the skin from a similar cause.
Hydrogen slowly reduces the solution of silver nitrate with
deposition of metallic silver (Beketoff).
Characters of Silver Salts.-Solutions of the silver salts
are precipitated black by hydrogen sulphide and by ammonium.
sulphide.
Potassium hydrate forms an olive-green precipitate of silver
oxide, insoluble in excess. Ammonia does not precipitate them.
Hydrochloric acid and the soluble chlorides form a white
precipitate of silver chloride, insoluble in either cold or boiling
nitric acid, but soluble in ammonia.
Potassium iodide gives a yellow precipitate, almost insoluble
in ammonia.
Silvering. This operation consists in covering the common
metals or glass with a coating of silver more or less thick.
The metals are silvered by either amalgamation or galvanic
deposition. In the latter and preferable operation, a solution
of the double cyanide of silver and potassium is generally used.
Mirrors and glass articles in general are silvered by the re-
duction of a silver salt by aldehyde, glucose, or tartaric acid.
The following receipt is given by Liebig: a solution of 10
grammes of silver nitrate is supersaturated with ammonia and
rendered strongly alkaline by caustic soda. The volume of
the liquid should be 1450 c.c. Another solution is prepared
by dissolving 1 part of milk sugar in 10 parts of water.
latter solution is mixed with its own volume of the first solu-
tion, and the glass to be silvered is washed with alcohol and
immersed in the liquid. The reduction of the silver salt begins
immediately, and does not require the aid of heat.
The
The experiment may easily be made in a glass flask, the
interior of which will be uniformly silvered.
Assaying of Silver.-This name is applied to the methods
which serve for the analysis of alloys of silver and copper, such
as coin, medals, silverware, and jewelry. The assay may be
conducted by the dry way or by the wet way.
The dry assay consists in the operation called cupellation
(Fig. 118). A certain quantity of metallic lead is melted in
a cupel of bone-ash in a reverberatory furnace, and a weighed
quantity of the alloy of silver and copper, carefully wrapped
in a small piece of paper, is placed upon the fused metal. The
silver dissolves in the melted lead, and a ternary alloy is thus
obtained which is exposed to the action of air at a red heat.
33*
390
ELEMENTS OF MODERN CHEMISTRY.
Under these conditions, the lead and copper become oxidized d;
the oxide of lead fuses, and the melted litharge, which should
be in great excess in proportion to the oxide of copper, dis-
solves the latter, and with it is absorbed by the porous cupel.
The phenomenon of brightening (page 360) indicates the ter-
mination of the process.

FIG. 118.
The wet assay, invented by Gay-Lussac, consists in adding
to a solution in nitric acid of a known weight of the alloy of
silver and copper, a titered solution of sodium chloride, that
is, a solution containing an exactly known weight of salt in one
litre of water. This solution is cautiously added until it no
longer precipitates silver chloride, and the quantity of silver
present is calculated by the volume of the titered solution that
has been required to completely precipitate the silver in the
form of chloride. As the latter readily deposits from a liquid
that is carefully agitated, it is easy to catch the termination
of the operation, that is, the precise moment when all of the
silver is precipitated and the addition of the titered liquid
must be arrested.
GOLD.
391
Process. Two titered solutions are used to precipitate the
silver: 1st, a normal solution, containing 0.5417 gramme of
sodium chloride per decilitre, a quantity sufficient to precipitate.
one gramme of silver; 2d, a decinormal solution, that is, one
containing the same quantity of sodium chloride per litre, so
that 1 c.c. of this liquid will precipitate one milligramme
of silver. To analyze an alloy of silver, a coin, for example,
such a quantity is weighed as would contain one gramme of
silver, if the proportion of silver were a little less than the
extreme limit allowed. If the alloy ought to contain 900
thousandths of pure silver, with a tolerance of 2 thousandths,
it would be rejected should it contain only 897 thousandths.
We suppose, however, that the latter is its quality, and
weigh a quantity of the alloy which would then contain one
gramme of pure silver, that is, 1.1148 grammes. This alloy
is dissolved in nitric acid, and one decilitre of the normal solu-
tion is added. All of the silver should not be precipitated, for
the standard of the alloy should be above 897. This is deter-
mined by adding to the clarified liquid one or more cubic cen-
timetres of the decinormal solution, until the liquid ceases to
be troubled by a fresh addition. As each cubic centimetre of
this solution corresponds to one milligramme of silver, we must
add to the gramme of silver at first precipitated as many
milligrammes as we have added cubic centimetres of the deci-
normal solution, the last cubic centimetre added counting for
only half a milligramme. Knowing the quantity of pure silver
contained in 1.1148 grammes of the alloy analyzed, the
standard of the latter is determined by a simple calculation.
GOLD.
Au(Aurum) 197
Natural State.-Gold is one of the most anciently known
metals. It is generally found in the native state, either in
streaks or veins, or in sand. It ordinarily occurs in scales or
rounded grains disseminated in alluvial sands, or in the rocks
whose disintegration produces such sands. It is well known
that gold-dust is suspended in the waters of certain rivers.
Gold is sometimes found combined with silver, lead, copper,
and tellurium.
392
ELEMENTS OF MODERN CHEMISTRY.
Extraction.-Gold is extracted from auriferous sand by
washings, which remove the particles lighter than the gold.
These washings are conducted in wooden troughs (cradles), or
on inclined tables, the gold sinking to the bottom of the cradles
or remaining on the tables. When it is in particles too minute
to be separated mechanically from the sand, which still remains
in small quantity, the whole is agitated with mercury; the gold
dissolves. The amalgam thus obtained is compressed in a
chamois-skin, which allows the passage of the excess of mer-
cury. When the solid residue is distilled the gold remains.
Auriferous quartz rocks are crushed to powder, which is then
subjected to washings. Mercury is sometimes employed to ex-
tract the gold from the pulverized rock. The following process
has been employed for some years in California and Australia.
The crushed rock, with mercury, water, and two cast-iron balls,
is introduced into basins, to which a rotating motion is given
(Fig. 119). By the friction of the balls it is soon reduced to

FIG. 119.
an impalpable powder, which remains suspended in the water,
and is carried out with the latter through openings in the upper
part of the basins, while the gold amalgamates with the mer-
cury.
Native gold, as well as that extracted from different minerals,
is nearly always alloyed with silver. The two metals are sep-
arated by the wet way, by attacking the alloy with either nitric
or sulphuric acid. Nitrate or sulphate of silver is formed, the
latter being soluble in hot water. The gold remains in a pul-
verulent state. It is to be remarked that the alloy of gold and
silver must be rich in silver in order that this process, called
refining, can be applied. Hence it is sometimes necessary to
OXIDES OF GOLD-CHLORIDES OF GOLD.
393
increase the proportion of silver by melting the alloy with that
metal.
An alloy of gold and silver rich in gold may also be treated
with aqua regia. Both metals are converted into chlorides;
that of silver is insoluble, while that of gold dissolves. When
ferrous sulphate is added to the yellow solution of chloride of
gold, a precipitate of metallic gold is obtained, the chlorine
acting upon the iron of the ferrous sulphate which is thus
transformed into ferric salt.
Properties of Gold.-Pure gold has a beautiful yellow color.
In thin leaves it is translucent, allowing the passage of a green-
ish light. Its density is 19.5. It is quite soft, and is the most
malleable and most ductile of the metals.
It melts at 1200°, and volatilizes at a higher temperature.
Its vapor is green.
It is unaltered by the air at all temperatures. Sulphuric,
hydrochloric, nitric, and phosphoric acids have no action on it
either in the cold or when aided by heat. It is dissolved by
nitro-hydrochloric acid.
Some gold leaf may be boiled with hydrochloric acid in a
test-tube; the gold will resist the action of the acid, and will
retain its lustre. Some more gold leaf may be boiled with pure
nitric acid in another tube, and again the metal will not be
attacked. But on mixing the two liquids, the gold will be dis-
solved with disengagement of red vapors. Gold trichloride will
be formed, and will color the liquid yellow.
OXIDES OF GOLD.
There are two compounds of gold and oxygen, a monoxide,
Au2O, and a trioxide, Au20³. The latter forms compounds
with the bases. When magnesia is added to solution of auric
chloride, an insoluble yellow precipitate of magnesium aurate
is formed; when this is decomposed by nitric acid it leaves auric
hydrate. This hydrate is yellow; it easily parts with its water,
and is converted into a brown-black powder of auric oxide.
The latter is not stable, being decomposed by light and by a
temperature of about 250°.
CHLORIDES OF GOLD.
Aurous chloride, AuCl, is obtained as an insoluble yellow
powder by heating auric chloride to 230°.
R*
394
ELEMENTS OF MODERN CHEMISTRY.
}
Auric chloride or trichloride of gold, AuCl³, is prepared by
dissolving the metal in aqua regia. After concentration the
liquid solidifies, on cooling, to a dark-red, crystalline and deli-
quescent mass.
The solution of auric chloride is yellowish-brown when con-
centrated, pure yellow when dilute. It is decomposed by light.
It colors the skin violet, and is reduced by a great number of
bodies. Phosphorus, and hypophosphorous, phosphorous and
sulphurous acids precipitate from it metallic gold. It is the
same with most of the metals, which combine with the chlorine,
setting free the gold. A brown precipitate of metallic gold is
immediately obtained on adding a solution of ferrous sulphate
to a solution of auric chloride. Auric chloride dissolves in
ether, which removes it from its aqueous solution when the
two liquids are agitated together.
If a solution of auric chloride be added to a mixture of
stannous and stannic chlorides in solution, a flocculent precipi-
tate of a purple color, more or less pure according to the con-
centration of the solutions and the proportions of the mixture,
will be formed. It is purple of Cassius, a compound employed
in painting on glass and porcelain. It contains tin, gold, oxy-
gen, and hydrogen, but its constitution is not well known.
Auric chloride forms crystalline compounds with the alkaline
chlorides. When a mixture of chloride of gold and sodium
chloride is evaporated until a pellicle forms on its surface, yellow
crystals containing NaCl. AuCI+ 2H2O, are formed on cooling.
Gilding. Several processes are used for gilding metals, such
as silver and copper. The objects may be gilded by amalga-
mation, by dipping, or by galvanic deposition.
Gilding by Amalgamation.-Gold readily alloys with mer-
cury, and the amalgam is used for gilding objects of silver and
copper. The pieces are heated to destroy greasy matters, and
are then cleaned by dipping them into dilute sulphuric acid,
after which they are washed and dried with saw-dust. They
are then rubbed with a brush of brass wires dipped into a solu-
tion of mercurous nitrate, and then with a brush impregnated
with an amalgam of one part of gold and eight parts of mer-
cury. They are afterwards heated to volatilize the mercury,
an operation dangerous to the health of the workmen, and which
should be conducted in a furnace having a good draught. The
pieces thus gilded are dull; they become lustrous after suitable
washings and polishings.
PLATINUM.
395
Gilding by Dipping.-Copper objects may be covered with
a thin film of gold by dipping them into a boiling solution of
carbonate and phosphate of sodium to which auric chloride
has been added.
Electro-Gilding.-The copper objects, previously heated and
cleaned by dilute sulphuric acid, are plunged for a few seconds
into dilute nitric acid and then wiped dry. They are then
connected with the negative pole of a battery and dipped into
a bath composed of 1 part of cyanide of gold, 10 parts of potas-
sium cyanide, and 100 parts of water. A plate of gold plunged
into the same bath constitutes the positive pole. When the
current passes, the objects become covered with a uniform and
adherent coating of gold. As the metal is precipitated from
the solution, it is replaced by an equivalent quantity from that
which constitutes the positive pole, and which dissolves. The
bath thus retains a constant composition. The same process
is applicable to clectro-silvering.
Assaying of Gold Alloys.-Gold is assayed by cupellation.
The alloy is first melted with silver, so that the quantity of the
latter metal present may be at least triple that of the gold.
This alloy is submitted to cupellation, an operation which
presents no difficulty, for gold rich in silver does not spit.
The button is hammered out to a thin sheet, reheated and
formed into a little cornet, which is introduced into a small
flask and heated with nitric acid of 22° Baumé. After several
minutes' boiling the greater part of the silver is dissolved; the
liquid is then decanted and replaced by more concentrated nitric
acid. All of the silver dissolves and the gold remains in the
form of a but slightly coherent cornet. It is washed, heated to
redness in a crucible to give it coherence, and finally weighed.
PLATINUM.
Pt 197.5
Natural State and Treatment of Platinum Ores.-Plat-
inum is found native, generally in alluvial sands. Its principal
deposits are in the Ural Mountains, Brazil, and New Granada.
The platinum ore, extracted from the sand by washing, contains,
independently of 73 to 86 per cent. of platinum, various other
metals, such as iridium, palladium, rhodium, osmium, ruthenium,
gold, iron, and copper; an alloy of osmium and iridium, and
396
ELEMENTS OF MODERN CHEMISTRY.
various minerals, such as titaniferous iron, chrome iron, pyrites,
etc. The ore is well washed to remove the sand, and treated
with dilute aqua regia which dissolves the gold, iron, and cop-
per; it is then heated with concentrated hydrochloric acid and
nitric acid is gradually added. The aqua regia dissolves the
platinum and certain of its accompanying metals, leaving the
osmium and iridium. The solution is neutralized with sodium
carbonate and treated with a solution of cyanide of mercury,
which precipitates palladium cyanide. A solution of ammo-
nium chloride is added to the filtered liquid, and forms an
abundant precipitate of ammonium and platinum double chlo-
ride, which is generally mixed with a small quantity of ammo-
nium and iridium double chloride. This precipitate is calcined
at a dull-red heat, and leaves a dull-gray, spongy residue. It
is spongy platinum. It contains a small quantity of iridium.
To give coherence to this sponge and convert it into a mal-
leable and ductile metal, it is reduced to powder in a wooden
mortar and triturated with enough water to convert it into a
perfectly homogeneous paste. This paste is introduced into a
slightly-conical cylinder of brass or iron, and compressed first.
with a wooden piston, then by a steel rod. The compression
is finished by the aid of a hydraulic press, and the slightly-
conical cylinders so formed are heated to whiteness and forged
under the hammer, as iron is forged.
H. Sainte-Claire Deville and Debray have recently extracted
the metal by simple fusion of the ore. The fusion is effected
in a lenticular cavity cut in two large masses of quick-lime,
placed one above the other. A current of illuminating gas is
directed into this furnace, and the combustion is supported by
a continual supply of oxygen.
Properties of Platinum.-Platinum has a grayish-white
lustre. It melts only at the highest attainable temperatures.
The density of the cast metal is 21.1; that of the forged metal
21.5. It softens at a white heat, and can then be forged and
welded like iron.
The experiments of H. Deville and Troost have shown that a
red-hot platinum tube allows hydrogen to pass through its pores.
Platinum has the curious property of condensing gases on its
surface, and this property is the cause of certain chemical phe-
nomena that were formerly attributed to mere contact of the
metal.
If a morsel of platinum-sponge be introduced into a small
CHLORIDES OF PLATINUM.
397
jar filled with an explosive mixture of oxygen and hydrogen,
the gases will combine instantly, with explosion.
This property is most highly developed in platinum-black,
for in this form the metal exists in an extreme state of
division. It may be prepared by reducing a solution of
platinic chloride by zine; or platinum dichloride may be boiled
with potassium hydrate, and alcohol or a solution of sugar
gradually added to the liquid, which must be continually
stirred. The platinum is precipitated as a black powder.
Platinum is unaltered by the air. It is not attacked by
either nitric, hydrochloric, or sulphuric acids, even boiling. It
dissolves in aqua regia. The alkaline hydrates attack it at high
temperatures on contact with the air. It is the same with the
alkaline nitrates.
There are two oxides of platinum, a monoxide, PtO, and a
dioxide, PtO.
CHLORIDES OF PLATINUM.
These are the more important compounds of platinum.
There are two, a dichloride, PtCl², and a tetrachloride, PtCl*.
Platinum dichloride is obtained by cautiously heating the
tetrachloride to 200°. Chlorine is disengaged, and after cool-
ing, the residue is exhausted with boiling water, which leaves
an olive-green powder, constituting the dichloride. When
ammonia is added to a solution of platinum dichloride in
hydrochloric acid, a green, crystalline powder separates after
some time.
It is called green salt of Magnus, and contains
PtCl² + 2NH³
It may be regarded as the dichloride of platinoso-diammonium.
Pt"
H²
N2.C12
H2
H²
It is derived from two molecules of ammonium chloride by
the substitution of an atom of diatomic platinum for two atoms
of hydrogen.
Platinum tetrachloride, or platinic chloride, PtCl, is
formed when platinum is dissolved in aqua regia. A red-
brown solution is obtained, which, after concentration and cool-
ing, deposits red-brown needles of hydrated platinic chloride.
34
398
ELEMENTS OF MODERN CHEMISTRY.
The crystals lose their water when heated, and are converted
into a dark, red-brown mass, which constitutes the anhydrous
chloride PtCl. This body absorbs moisture when exposed to
the air. It is very soluble in water, alcohol, and ether.
If a solution of ammonium chloride be added to a solution
of platinic chloride, a yellow, crystalline precipitate of plati-
num and ammonium double chloride is immediately formed.
This body is but little soluble in cold water, but more soluble
in boiling water, from which it is deposited in microscopic,
regular octahedra. It is almost insoluble in alcohol. It contains
PtC14.2NH CI
A yellow, crystalline precipitate of double chloride of plati-
num and potassium is obtained, in the same manner, on adding
a solution of platinic chloride to a solution of a potassium salt,
if the liquids be not too dilute.
PtCl¹.2K Cl
ORGANIC CHEMISTRY.
GENERAL IDEAS UPON THE CONSTITUTION
OF ORGANIC COMPOUNDS.
ORGANIC CHEMISTRY studies the history of the compounds
of carbon. The most simple of these are the gases carbon
monoxide and carbon dioxide; each contains but a single atom
of carbon. In this respect they resemble the inflammable gas
which is disengaged from the mud of marshes; it contains one
atom of carbon combined with four atoms of hydrogen.
The gas hydrogen dicarbide or ethylene, which has already
been mentioned, contains two atoms of carbon united with four
atoms of hydrogen. A great number of compounds are known
which contain only carbon and hydrogen, and they are called
hydrocarbons or carburetted hydrogens. The atoms of carbon
are aggregated in them, together with the atoms of hydrogen.
Other elements are often added to the preceding, forming
molecules more or less complex. The carbon atoms form as it
were the framework, and the carbon compounds possess pecu-
liar properties precisely on account of the easy facility with
which the atoms of carbon accumulate in one and the same
molecule, and link themselves in some manner one to another.
The following developments will give some idea of the mode
of generation and the structure of organic molecules.
The most Simple Organic Compounds.-Their Composi-
tion proves Carbon to be a Tetratomic Element.—The most
simple of the hydrocarbons is marsh gas.
When this gas is submitted to the action of chlorine, one or
more atoms of hydrogen may be removed from it; they com-
bine with the chlorine and are disengaged in the form of hy-
drochloric acid gas. The curious fact, first noticed by Dumas,
is then observed, that each atom of hydrogen which is removed
is replaced by an atom of chlorine. This substitution gives
399
400
ELEMENTS OF MODERN CHEMISTRY.
rise to a series of chlorinated compounds, which present the
most simple relations with marsh gas. The latter contains only
carbon and hydrogen. The chlorine compounds derived from
it by substitution, form with it the following series:
CH¹
marsh gas, or methane.
CH³C monochloromethane (methyl chloride).
CH2Cl2 dichloromethane (methylene chloride).
CHCB3 trichloromethane (chloroform).
CCI tetrachloromethane (carbon tetrachloride).
In each of these compounds a single atom of carbon is united
with four monatomic atoms. We have seen that the atoms of
chlorine and hydrogen are equivalent as regards their power
of combination. In the preceding compounds, the sum of the
atoms of hydrogen and chlorine which are combined with one
atom of carbon is invariably four, and this number cannot be
exceeded. But two atoms of a monatomic element may be re-
placed by one atom of a diatomic element. One atom of car-
bon, which unites with four atoms of hydrogen or chlorine,
may unite with two atoms of oxygen to form carbon dioxide
CO"2
and this compound is saturated like those preceding, for one
atom of oxygen is equivalent to two atoms of hydrogen or
chlorine. In carbon monoxide, CO", the affinity of carbon
not satisfied; hence this gas will unite directly with an atom
of oxygen to form carbon dioxide, or with two atoms of chlo-
rine to form chloro-carbonic gas.
CO" Cl²
In ammonia, one atom of nitrogen is combined with three
atoms of hydrogen; nitrogen is triatomic; hence it may replace
three atoms of hydrogen. A body is known which represents
marsh gas, in which three atoms of hydrogen are replaced by
one atom of nitrogen. This is the dangerous poison known as
prussic or hydrocyanic acid, and the composition of which is
represented by the formula
CN"H
In all of the compounds which have just been mentioned a
single atom of carbon is invariably united to a number of ele-
ments of which the united atomicities is always four, and never
more nor less than that number. It is then reasonable to
conclude that in them carbon plays the part of a tetratomic
INTRODUCTION TO ORGANIC CHEMISTRY.
401
element. This important fact, first exposed by Kekulé, can be
clearly understood if we represent the preceding atomic formulæ
in a graphic manner, that is, by symbols so arranged as to show
the reciprocal relations of the atoms and their mutual satura-
tion. In these formulæ a saturated atomicity is indicated by
a line of union, two atomicities by two lines, etc.
H
H-C-H
H
H
H-C-CI
H
Marsh gas.
Monochloro-
methane.
H
CI-α-CI
CI
CI-C-CI
Trichloromethane.
(Chloroform.)
Carbon
tetrachloride.
Cl
CI-C-O
H-C-N
O=C=O
Carbon dioxide.
Chlorocarbonic gas. Hydrocyanic acid.
There exists a very volatile, ethereal liquid, which represents
marsh gas, in which one atom of hydrogen is replaced by iodine.
It is the body known as methyl iodide, CH³I.
If this body be heated for a long time in a sealed tube with
a solution of potassium hydrate, potassium iodide will be grad-
ually formed, and the solution will contain a volatile, spirituous
liquid which can casily be separated by distillation, for it boils
at 66°. It is the same body which constitutes the most vola-
tile of the liquids which are formed in the destructive distilla-
tion of wood; it is called wood spirit, and its chemical name is
methylic alcohol.
The reaction by which it is formed is very simple. The
iodine of the methyl iodide combines with the potassium; but
when this iodine is removed, the carbon remains united to but
three atoms of hydrogen. It is no longer saturated, and it
therefore combines with the oxygen and hydrogen which were
united with the potassium in the potassium hydrate.
CH³I + KOH
CH³.OH+KI
It will be seen that the atom of oxygen alone does not com-
bine with the group CH", which is called methyl. It is accom-
panied by an atom of hydrogen, with which it remains united
in the new compound which is called methyl hydrate or
methylic alcohol. As has been said, this oxygen replaces the
iodine in the iodide of methyl, but as it possesses two atomici-
ties, and the carbon already united with H³ has only one free
atomicity, the atom of oxygen can only fix upon the carbon by
34*
402
ELEMENTS OF MODERN CHEMISTRY.
one of its atomicities; the other remains saturated by the atom of
hydrogen. The latter is then drawn into the combination, and is
united, not to the carbon, but to the oxygen. The reaction takes
place as if the atom of iodine were replaced by the group hy-
droxyl (OH) which is monatomic. Hence the relations between
the atoms in methyl hydrate are represented by the formula.
H
H-C-(OH)'
H
If we compare the constitution of the three bodies CH³Cl,
CH³I, CH³(OH), we notice that they contain a common ele-
ment, namely, the group CH³, which is united to chlorine, to
iodine, or to hydroxyl. Besides this, experiment has shown
us that methyl iodide can be transformed into hydrate. The
group methyl hence presents a certain stability and can pass
from one combination to another. This is expressed by saying
that it is a radical.
If methyl iodide be heated with an aqueous solution of
ammonia, among the products formed will be found the hydri-
odide of a base which represents ammonia in which one atom
of hydrogen is replaced by the group methyl. Potassium
hydrate sets this base at liberty. At ordinary temperatures
and pressures, it constitutes a gas, very soluble in water and
possessing a strong ammoniacal odor. It is methylamine. The
reaction by which it is formed is as follows: the iodine with-
draws one atom of hydrogen from the ammonia, which atom
of hydrogen is replaced by the group CH³.
CH*I + NH* = CH*(NH).HI
Methylamine hydriodide.
In methylamine then, the fourth atomicity of the carbon
atom is saturated by nitrogen, but as this element is triatomic
it brings into the combination two atoms of hydrogen which
saturate its two other atomicities. It may then be said that
in methylamine the fourth atomicity of carbon is saturated by
the group NH2. This is expressed in the following formula.
H
H-C-N-H²
H
H--(NH3)
H
H
H
Methylamine.
INTRODUCTION TO ORGANIC CHEMISTRY.
403
Generation of Hydrocarbons containing Several Atoms
of Carbon. The preceding compounds contain but a single.
atom of carbon, but starting with one of these compounds we
may produce more complicated organic molecules containing
several carbon atoms.
If methyl iodide be heated with sodium in sealed tubes,
sodium iodide is formed, and a gas, a hydrocarbon, is confined
under great pressure in the tubes. This gas escapes, and may
be collected, when the drawn-out points of the tubes are opened
in the blow-pipe flame. It is dimethyl, and has been formed
according to the following reaction:
2CH³I + Na2
Methyl iodide.
C²H+ 2NaI
Dimethyl, or ethane.
Two molecules of methyl iodide have entered into the reac-
tion, and the whole of the carbon of these two molecules is
found in one molecule of the hydrocarbon, C'Hº (CH3)2,
which results.
On losing their iodine the two methyl groups combine to-
gether. One of the carbon atoms attracts the other, exchanging
with it the fourth atomicity set free by the loss of the iodine.
Hence the iodine of one of the molecules of methyl iodide has
been replaced by the carbon of the other, which fixes upon the
group CH' by a single one of its atomicities, and at the same
time brings into the combination the three atoms of hydrogen
which saturate the other three atomicities. This is expressed
in the following formulæ :
H
H-C-H
1
H
H
H-C-I
H
H H
1
H-C-C-H
H H
Methane (methyl hydride). Methyl iodide. Dimethyl (ethyl hydride or ethane).
The mode of generation of this new hydrocarbon, which
contains two atoms of carbon, is worthy of consideration. It
results from the substitution of a methyl group for one atom of
hydrogen in methyl hydride. One atom of carbon, accompa-
nied by three atoms of hydrogen, fixes upon another atom of
carbon of which it completes the saturation. By this exchange
of atomicities each of the carbon atoms retains only three affin-
itics which are satisfied by three atoms of hydrogen. The
two methyl groups, CH3 + CH³ C2H6, are then united by
their carbon atoms, and are held together by the affinity of
404
ELEMENTS OF MODERN CHEMISTRY.
carbon for carbon. In methyl hydrate the group hydroxyl is
bound to the group CH3 by the affinity of carbon for oxygen.
In methylamine, the group NH' is united to the group CH" by
the affinity of carbon for nitrogen. In dimethyl, it is carbon
which is united to carbon. This has before been expressed by
saying that the atoms of this element possess a faculty to accu-
mulate in one and the same molecule.
It is in this curious property that must be sought the reason
for the existence of those innumerable compounds, more or less
rich in atoms of carbon, which constitute the immense field of
organic chemistry.
But it is important to study by new examples this mode of
formation of organic compounds.
Dimethyl, which we have seen is produced by the action of
sodium upon methyl iodide, is also known as ethyl hydride. If
one of its atoms of hydrogen be replaced by an atom of chlo-
rine, ethyl chloride, C'HCl, is obtained. Ethyl iodide, C²H³I,
represents ethyl hydride, in which one atom of hydrogen has
been replaced by iodine.
If a mixture of methyl iodide and ethyl iodide be heated
with sodium, among the products of the reaction will be found
a gas containing C3H8; it is the methylide of ethyl, resulting
from the combination of methyl, CH, with the group ethyl,
C2H5. It represents ethyl iodide in which the atom of iodine
has been replaced by a methyl group, the carbon of the latter
group being fixed by one of its atonicities to one of the carbon
atoms of the group C2H5.
In the same manner, by heating a mixture of propyl iodide,
C³H'I, and methyl iodide with sodium, we may add to the
propyl group, CH', a new atom of carbon escorted by its three
atoms of hydrogen.
HH
H-C-C-I
H H
Ethyl iodide.
HHH
H-C-C-C-H
HHH
HHHH
H-C-C-C-C-H, etc.
|
HHHH
Methyl-ethyl (propane). Methyl-propyl (butane).
Nothing prevents the continuation of these additions of car-
bon to incomplete hydrocarbons, that is, to the residues of the
subtraction of iodine from the saturated iodides, of which the
following are the names and formulæ :
CH³I
Methyl iodide.
C2H5I
Ethyl iodide. Propyl iodide.
CHI
C4H9I
Butyl iodide.
CH¹¹I, etc.
Amyl iodide.
INTRODUCTION TO ORGANIC CHEMISTRY.
405
The following hydrocarbons would then be formed succes-
sively:
CH3-CH3 C2H5-CH3 CH-CH3 C4H9-CH3 C5H"-CH³, etc.
Methyl-methyl Methyl-ethyl Methyl-propyl Methyl-butyl Methyl-amyl
(Hexane).
(Ethane).
(Propane).
(Butane).
(Pentane).
In all of these cases, the atoms of carbon united together
form, as it were, a continued chain, and the atoms of hydrogen
are grouped around them as satellites.
Homologous Bodies.-Very simple relations exist between
the hydrocarbons of which we have just studied the mode of
formation. They form a series of which each member differs
from the preceding by the addition of CH2. These relations
will appear clearly if the formulæ already given be replaced
by the crude formulæ :
4
CH methane.
C2H6 ethane.
C3H8 propane.
C4H10 butane.
C5H12 pentane.
This group of hydrocarbons constitutes what is called the
homologous series of marsh gas, or the series C"H2n+2.
Many other scries are known, the terms of which are related
to each other in the same manner, and the bodies which form
part of them may present the greatest differences in composition.
Sometimes they contain only carbon and hydrogen. Again,
they may contain oxygen or nitrogen in addition to these ele-
ments; in this case the former elements are united to carbon by
one or more of their atomicities, as has already been indicated.
In any organic body whatever, if an atom of hydrogen united
with carbon be replaced by a methyl group, CH³, the superior
homologue of that body is obtained, that is, the compound which
differs from the original body by the addition of CH². There
is a great resemblance in physical and chemical properties
between such homologues.
Some of these homologous series will be indicated farther on.
Immediate Principles and Chemical Species.-The four
elements, carbon, hydrogen, oxygen, and nitrogen, are the more
ordinary elements of organic compounds. Those which are
found in nature in the organs of plants and animals, and which
have been called by Chevreul immediate principles, contain
no others, excepting sulphur, which exists in certain of them.
406
ELEMENTS OF MODERN CHEMISTRY.
But nearly all of the other elements can be introduced artificially
into organic compounds; it is thus with bromine, iodine, phos-
phorus, arsenic, boron, silicon, and a great number of the metals.
In uniting with carbon, in different manners and in various
proportions, these elements form an innumerable multitude of
compounds, each of which has a fixed composition and definite
properties. These bodies constitute the chemical species, so to
say. When submitted to the action of reagents, all may be
modified in a thousand manners, and transformed into each
other. Sometimes their composition is simplified, one or more
carbon atoms being removed from the chain. Sometimes it is
complicated by the addition of new atoms of carbon.
All of these bodies contain carbon, and are distinguished
from each other:
1. By the number of carbon atoms contained in the molecule.
2. By the nature and arrangement of the other atoms com-
bined with the carbon.
3. By the arrangement of all of the atoms in the molecule.
The facts relative to the atomic composition of organic com-
pounds are obtained by elementary analysis and by the deter-
mination of the molecular weight.
ELEMENTARY ANALYSIS.
The object of elementary analysis is the determination of
the nature and proportion of the elements contained in any
given organic body. We can give here but a summary descrip-
tion of the processes employed, considering only those which
have for object the determination of carbon, hydrogen, and ni-
trogen. These, together, with oxygen, are the more ordinary
elements of organic combinations.
In a substance containing carbon, hydrogen, and oxygen,
the first two elements are determined directly in the same
operation; the oxygen is determined by difference. When,
in addition to the former elements, the body contains nitrogen,
the determination of this requires a separate operation.
Determination of Carbon and Hydrogen.-To determine
the proportion of carbon and hydrogen contained in 100 parts
of any given organic substance, the carbon is converted into car-
bon dioxide, which is collected and weighed, and the hydrogen
into water, which is condensed and weighed. These operations
are conducted according to the processes indicated by Liebig.
ELEMENTARY ANALYSIS.
407
For this end, the organic matter, previously dried with care, is
burned with an excess of cupric oxide. The operation is exe-
cuted in a combustion-tube of hard glass, which is wrapped with
a spiral of metallic foil to prevent it from bending and swell-
ing under the influence of the heat. Well-dried cupric oxide
is introduced into the tube, then an intimate mixture of the
substance to be analyzed with a large excess of the same oxide,
and the remainder of the tube is filled with pure cupric oxide.
The tube is then placed in a combustion furnace, and its
open extremity is put in communication with (1) an U tube, jg
(Fig. 120), containing fragments of calcium chloride in the first
branch, and pumice-stone impregnated with sulphuric acid in
the second; (2) a tube with five bulbs, h, called Liebig's potash
bulbs, containing a concentrated solution of potassium hydrate,
and followed by a small U tube, i, containing pumice-stone im-
pregnated with potassium hydrate in the first branch, and frag-
ments of potassium hydrate in the second. These different
tubes have first been accurately weighed. When the appa-
ratus is arranged, the combustion-tube is slowly heated, com-
mencing at the extremity B, and gradually extending the heat
so that each part of the tube is successively heated to redness.
The water formed by the combustion is collected in the first
U tube, the carbon dioxide is absorbed by the potassium hy-
drate in the bulbs. When the operation is terminated, the
drawn-out point of the combustion-tube is broken, and con-
nected by means of a caoutchouc tube with a gasometer con-
taining oxygen. An excess of the latter gas is then passed
through the combustion-tube, in order to drive out the traces
of carbon dioxide and aqueous vapor which it contains at the
end of the combustion. It is then only necessary to weigh the
water tube and the carbon dioxide tubes. The increase in
weight which is found indicates, on one hand, the quantity of
water, and on the other the quantity of carbon dioxide, pro-
duced by the combustion of the organic matter.
The compo-
sition of water and of carbon dioxide being known, it is easy
to deduce from the weight of these two bodies the quantities
of hydrogen and carbon contained in the analyzed substance,
and consequently the proportion of these two elements con-
tained in 100 parts of that substance.
Fig. 120 represents the operation towards its close: the
combustion-tube is in the gas-furnace, B, and communicates,
on the right with the tubes g, h, i, destined to receive the pro-
408
ELEMENTS OF MODERN CHEMISTRY.

-THIN BAJET
FIG. 120.
B
ELEMENTARY ANALYSIS.
409
ducts of the combustion, on the left with two large U tubes,
the first of which is filled with pumice-stone impregnated with
potassium hydrate to absorb traces of carbon dioxide, the
second with pumice-stone saturated with sulphuric acid to
absorb moisture. Through these tubes is passed the oxygen,
at the close of the operation, to expel the last portions of carbon
dioxide and vapor of water.
When the substance contains carbon, hydrogen, and oxygen,
the proportion of oxygen is the difference between the total
percentage of carbon and hydrogen found and 100.

B
FIG. 121.
Determination of Nitrogen.-Nitrogen may be determined
by two processes. The first consists in burning a given weight
of the nitrogenized substance with an excess of cupric oxide.
The carbon of the substance is converted into carbon dioxide;
the hydrogen is converted into water; the nitrogen is disen-
gaged. The gases, nitrogen and carbon dioxide, are received
in a graduated jar standing on the mercury-trough and con-
taining potassium hydrate. The carbon dioxide is absorbed,
the nitrogen remains. At the close of the operation, the last
traces of nitrogen are expelled by a current of carbon dioxide.
The volume of nitrogen is then measured, and its weight de-
duced from its volume (Dumas).
The second process (Fig. 121) consists in decomposing the
nitrogenized organic matter with an alkali at a high tempera-
S
35
410
ELEMENTS OF MODERN CHEMISTRY.
ture. By this means all of the nitrogen is converted into
ammonia. The substance is intimately mixed with soda lime,
that is, lime impregnated with caustic soda. The mixture is
heated to redness in a tube of hard glass, and the ammonia is
received in a tube with three bulbs containing dilute hydro-
chloric acid. Ammonium chloride is formed; when the opera-
tion is terminated, the liquid containing the salt is mixed with
a solution of platinic chloride. It is then evaporated and
exhausted with alcohol, which leaves the platinum and ammo-
nium double chloride, 2(NHCl) + PtCl. The latter is col-
lected upon a tared filter, then washed and dried. From its
weight is calculated that of the nitrogen contained in the
organic substance (Will and Varrentrapp).
The ammonia disengaged may also be received in 10 cubic
centimetres of a normal solution of sulphuric acid, that is, an
acid liquor containing a known quantity of sulphuric acid in
a determined volume.
The strength of this acid is determined by neutralizing 10
c.c. of it with a dilute alkaline solution of known strength and
noting the volume of the latter required. The same operation
is repeated with the 10 c.c. of which the acid has been par-
tially neutralized by the ammonia. The quantity of ammonia
corresponds to the difference between the volumes of the alka-
line liquid employed in these two operations, and can easily be
calculated by simple proportion (Peligot).
Determination of the Molecular Weight of Organic Sub-
stances.—Elementary analysis permits the determination of
the centesimal composition of organic substances. This is
indispensable, but it is insufficient for the establishment of
their atomic composition, that is, the number of atoms of car-
bon, hydrogen, oxygen, and nitrogen which are contained in a
single molecule of a given organic compound. But if the
weight of the molecule be known (hydrogen being taken as
unity), it is easy to deduce the atomic composition from the
figures given by elementary analysis, as will be seen by the
following example. By elementary analysis it is found that
100 parts of acetic acid contain
Carbon.
Hydrogen.
Oxygen
•
40.
6.67
53.33
100.00
On the other hand, methods which will be described have
ELEMENTARY ANALYSIS.
411
shown that the molecular weight of acetic acid is 60; that is to
say, the total weight of the atoms of carbon, hydrogen, and
oxygen contained in a molecule of acetic acid, is 60.
Hence by the following proportions:
If 100 parts acetic acid contain 40
66
"
((
64
of carbon,
60 parts contain x.
y.
66
2.
4; z =
32.
6.67 of hydrogen,
53.33 of oxygen
From which, x = 24; y
www.com
Hence 24 represents the weight of the atoms of C contained in a molecule
of acetic acid.
4 represents the weight of the atoms of II contained in a molecule of acetic
acid.
32 represents the weight of the atoms of O contained in a molecule of acetic
acid.
By dividing these numbers by the weights of the respective
atoms, the number of atoms of C, H, and O contained in a
molecule of acetic acid is readily determined.
24 + 12
2 atoms of carbon.
4 ÷
1
4
(6
32 ÷ 16
2
hydrogen.
oxygen.
Hence the formula of acetic acid is C²H¹O².
After the analysis of an organic substance has been made, it
is only necessary to determine its molecular weight in order to
establish its atomic composition. Several processes are em-
ployed for this determination, of which the most sure is the
determination of the vapor density.
We know that if one atom of hydrogen occupy one volume,
the molecules of organic substances occupy two volumes. To
find the weights of these molecules it is then sufficient to deter-
mine their vapor densities compared to hydrogen; that is, to
find the weight of one volume of their vapors, that of one
volume of H being taken as unity. The number found mul-
tiplied by 2 gives the weight of two volumes, that is, the weight
of the molecule.
Hence a simple determination of the vapor density is suf-
ficient for the establishment of the molecular weight. Ordi-
narily these vapor densities are given as compared with air
taken as unity. To bring them to the hydrogen scale it is
then only necessary to multiply them by 14.44, which is the
exact relation of the density of air to that of hydrogen. Thus
the vapor density of acetic acid, determined at 295°, has been
found equal to 2.083 (Cahours). This number multiplied by
14.44 gives for the density compared to hydrogen 30.08. The
412
ELEMENTS OF MODERN CHEMISTRY.
latter number expresses the weight of one volume of acetic
acid vapor, the weight of one volume of hydrogen being con-
sidered as 1. The weight of two volumes of this vapor, that
is, the weight of the molecule, will then be 2 X 30.08 =
60.16, a number very nearly approaching 60, the theoretical
molecular weight.
The method just described can only be applied to substances
which can be volatilized without decomposition. For other
bodies another method must be adopted. The latter consists
in forming with the organic body definite combinations, the
atomic composition of which may be known. We will again
consider acetic acid. Salts may be formed with this acid, and
we know that these salts contain one atom of metal. We may
then analyze silver acetate. 100 parts of that salt contain
64.67 parts of silver. This fact being known, it is easy to deter-
mine the molecular weight of silver acetate. Since the latter
contains one atom of silver, we can conclude, if 64.67 parts of
silver are contained in 100 parts of silver acetate, 108 parts
of silver, that is, one atom, are contained in x parts of silver
acetate; whence x=167. This number represents the molec-
ular weight of silver acetate. That of acetic acid may be de-
duced by substituting the atomic weight of hydrogen for that
of silver, which gives for the molecular weight of acetic acid 60.
Analogous operations and reasoning permit the determina-
tion of the molecular weights of bodies playing the part of
bases. They are combined with an acid, the molecular weight
of which is known, and the composition of the combination
furnishes the data for the calculation of the molecular weight
of the base. This method can be applied in a large number
of analogous cases, and presents a great generality.
ISOMERISM, METAMERISM, POLYMERISM.
Elementary analysis demonstrates that many bodies which
differ in their physical and chemical properties, possess exactly
the same centesimal composition. Such bodies are said to
be isomeric. Two kinds of isomerism exist. Sometimes the
isomeric bodies contain the same number of similar atoms in
molecules of the same size, and differ only by the arrange-
ment of these atoms; sometimes they contain similar atoms
united in the same proportion, but not in the same number, in
molecules of unequal magnitude.
ISOMERISM, METAMERISM, POLYMERISM.
413
In both cases the centesimal composition is the same, for it
depends only on the relative number of the atoms.
The first kind of isomerism constitutes metamerism; the
second, polymerism. Acetic acid and methyl formate are an
example of two metameric bodies. Each contains 2 atoms of
carbon, 4 of hydrogen, and 2 of oxygen; their molecules are
equal in size, but different in atomic structure. The latter fact
may be expressed by the following formula:
C2H30.OH acetic acid
CH³O.OCH methyl formate
The first expresses that acetic acid contains a group of atoms,
C'H³O, acetyl, which is united with hydroxyl, OH; the second,
that methyl formate contains a group, CHO, formyl, which is
united with oxymethyl, CH³O. The difference in the atomic
arrangement becomes evident, if the preceding formula be
developed in the graphic manner.
O-H
C=O
0-CH3
C=O
CH³
Acetic acid.
H
Methyl formate.
By adopting the theory of atomicity, chemists have been.
enabled to discover the atomic structure of a great number of
combinations, as we have seen in the case of acetic acid and
methyl formate. Such considerations are of great importance
for the interpretation of isomerism, and we will have frequent
occasion to refer to the subject in the course of this work.
Acetic acid and glucose or grape-sugar present an example
of polymerism. Both contain the atoms of carbon, hydrogen,
and oxygen, united together in the same proportions, but the
'molecule of the second contains three times as many of each
as that of the first.
3 X C²H+02
C2II402 acetic acid.
C6H12O6 glucose.
Among the more important and better known cases of po-
lymerism, may be mentioned the numerous hydrocarbons which
present the centesimal composition of ethylene or olefiant gas,
and which differ from it by the regularly increasing number of
their atoms of carbon and hydrogen. These bodies form the
following homologous series:
35*
414
ELEMENTS OF MODERN CHEMISTRY.
C2H+
ethylene.
C3H6
propylene.
C4H8
butylene.
C51110
anylene.
C6H12
hexylenc.
C7H14
heptylene.
C8H16
octylene, etc.
It will be seen that butylene contains twice as many carbon
and hydrogen atoms as ethylene, hexylene contains three times
as many, etc.
FUNCTIONS OF ORGANIC COMPOUNDS.
In the study of mineral chemistry it has been seen that
bodies present great differences in properties, according to their
composition. Some are simple and apt to enter into combina-
tion; others are compound and indifferent; the first are more
or less energetic in their affinities, the others saturated and
satisfied. In one case, we have examined either more or less
powerful acids or bases, some of which are hydrated, as potassa
and soda, others anhydrous, as the oxides of lead and silver.
In the other case, we have studied the salts resulting from the
union of the former bodies.
In organic chemistry we again encounter various kinds of
bodies which have different functions, according to their com-
position.
It may be said, in a general manner, that the properties of
compound bodies depend upon the nature of the atoms and
their arrangement in the molecule. In treating of isomerism,
the influence of the latter condition has been indicated; that
of the former is still more powerful.
Water and potassium hydrate are both constituted, and in
an analogous manner, of three elementary atoms.
Each con-
tains one atom of oxygen united to two monatomic atoms.
HOH
Water.
KOH
Potassium hydrate.
But what a difference in their properties! But may not
this be expected when it is considered that one contains the
energetic metal potassium, in the place occupied in the other
by the light gas hydrogen? Is the difference between potassa
and water greater than that between potassium and hydrogen?
MONATOMIC COMPOUNDS.
415
And if for the two atoms of hydrogen we substitute two atoms
of chlorine, is it not to be expected that hypochlorous oxide.
Cl-O-CI
the molecule of which is similar in structure to that of water,
shall differ from the latter in its properties as much as chlo-
rine differs from hydrogen? It is thus that the nature of the
elements contained in compound bodies is the dominant condi-
tion in the manifestation of their properties.
The following considerations are of a nature to demonstrate
the truth of this proposition inasmuch as concerns organic
compounds:
MONATOMIC COMPOUNDS.
Saturated Hydrocarbons.-The hydrocarbons belonging
to the series of marsh gas are all saturated. Consider, for
example, CH; all of the atomicities of two atoms of carbon
are satisfied by the union of the latter together and with six
atoms of hydrogen.
H H
H-C-C-H
HH
Ethane, or ethyl hydride.
It is the same with all of its homologues; the hydrides of
propyl, butyl, amyl, etc., are all saturated hydrocarbons, as will
be seen by developing the formula of any one of them, pentane,
for example:
HHHHH
1
H-C-C-C-C-C-H
1
} 1
HHHHH
Pentane, or amyl hydride.
All of these bodies are incapable of fixing other elements
by direct addition, but they may be modified by substitution,
that is, one or several of their atoms of hydrogen may be
replaced by other elements.
Monatomic Chlorides, Bromides, and Iodides. By the
reaction of bromine upon any of the hydrocarbons, we may
416
ELEMENTS OF MODERN CHEMISTRY.
obtain compounds containing an atom of bromine in the place
of an atom of hydrogen.
C2H6 +
+ Br²
Ethane.
C²H³Br + HBr
Ethyl bromide.
A saturated and indifferent hydrocarbon is thus converted
into a bromide.
The corresponding chloride and iodide exist, possessing the
same constitution as the primitive hydrocarbon, and forming
with it the following series:
C2H6
ethane.
C2H5Cl ethyl chloride.
C2H5Br ethyl bromide.
C2H5 ethyl iodide.
To the other hydrocarbons correspond chlorides, bromides,
and iodides analogous to the preceding.
groups are known:
CH¹ methane.
CH3C methyl chloride.
CH³Br methyl bromide.
CH³I methyl iodide.
C5H12
Thus, the following
pentane.
C5¹¹C amyl chloride.
C5H¹¹Br amyl bromide.
C5H1I amyl iodide.
All of these bodies may be made to undergo the most varied
transformations. They may be attacked by a number of re-
agents, to which they present a hold, as it were, since the chlo-
rine, bromine, and iodine which they contain are gifted with.
powerful affinities.
The residues resulting from the subtraction of the chlorine,
bromine, or iodine then enter into other combinations. It will
be remarked that these residues represent the saturated hydro-
carbons from which one atom of hydrogen has been removed.
,
CH3
C2H5
CH³Br
C2H5Br
C5H11 C5H¹¹Br
Br, or CH¹
H
Br, or C2H6
H
Br, or C5H12
H
The atoms of carbon contained in these residues, CH³, C2H5,
and CH", are no longer entirely saturated, since Cl, Br, I, or
H has been removed, elements which saturated one atomicity.
Therefore, these residues are capable of entering other com-
binations, but as they possess only one free atomicity, they can
only saturate one when they combine. This is expressed by
saying that they play the part of monatomic radicals. The
chlorides, bromides, and iodides from which they are derived
are themselves monatomic.
MONATOMIC COMPOUNDS.
417
Alcohols. The neutral organic hydrates corresponding to
the preceding chlorides, bromides, and iodides, are called
alcohols.
If ethyl iodide be heated for a sufficiently long time with
potassium hydrate, potassium iodide will be formed, and the
alkaline liquid will contain alcohol which may be separated.
This body is ethyl hydrate and is formed according to the
following reaction:
C2H5I + KOH
Ethyl iodide.
KI CH5.OH
Ethyl hydrate.
Analo-
It is formed, as is seen, by double decomposition. The
potassium having removed the iodine from the ethyl iodide,
the monatomic residue C2H5 combines with the monatomic
residue OH. Alcohol is then the hydrate which corresponds
to the iodide, CHI, and to the hydrocarbon, C²Hº.
gous hydrates correspond to the other hydrocarbons of the
same series; they constitute the series of monatomic alcohols,
and may be defined as derived from the saturated hydrocarbons
by the substitution of the group hydroxyl for one atom of
hydrogen. The alcohols now known are numerous; the follow-
ing are some of them:
CH3.OH methyl hydrate, or methylic alcohol.
C2115.OH ethyl hydrate, or ethylic alcohol.
CH7.OH propyl hydrate, or propylic alcohol.
C4H9.OH butyl hydrate, or butylic alcohol.
C5H1.OH amyl hydrate, or amylic alcohol.
C6H13.OH hexyl hydrate, or hexylic alcohol.
CH15.OH heptyl hydrate, or heptylic alcohol.
C8H17.OH octyl hydrate, or octylic alcohol.
Each member of this series differs from that which follows
by -CH². All are allied by analogous properties. These two
conditions characterize homologous bodies. The alcohols of
which the general formula is CnH2n+¹OH, form one of the most
important series of homologues.
If one of these alcohols be heated with hydrochloric, hydro-
bromic, or hydriodic acid, water will be formed and the alcohol
will be converted into a monatomic chloride, bromide, or iodide.
In this reaction the hydroxyl, OH, is replaced by chlorine,
bromine, or iodine.
C²H³.OH + HCl
Ethyl hydrate.
H2O + C²H³Cl
Ethyl chloride.
The bodies thus formed are the monatomic chlorides, bro-
S*
418
ELEMENTS OF MODERN CHEMISTRY.
mides, or iodides before considered. These experiments expose
the relations which exist between the latter compounds and the
corresponding hydrates, which are the alcohols.
Monobasic Acids.—Acetic acid, which exists in vinegar, is
a derivative of alcohol, of which it is one of the products of
oxidation. It is formed under many conditions, one of which
is the oxidation of alcohol vapor on contact with platinum
black and the air.
C2H5.OH
+ 0²
Alcohol.
C2H3O.OH + H2O
Acetic acid.
In this reaction an atom of oxygen removes two atoms of
hydrogen to form water, and the place of these two atoms of
hydrogen is filled by another atom of oxygen.
The group
ethyl, C'H³, thus becomes the group acetyl, C²H³O, and if
alcohol be the hydrate of ethyl, acetic acid is the hydrate of
acetyl. We can account for this reaction by developing the
formulæ of alcohol and acetic acid according to the principles
before explained.
H H
11
H-C-C-OH + 0²
1 1
H H
Alcohol.
но
||
H-C-C-OH + H2O
H
Acetic acid.
In alcohol, the second carbon atom is combined with two
atoms of hydrogen and with one group hydroxyl, while in
acetic acid it is combined with an atom of oxygen and a group
hydroxyl.
Acetic acid contains two atoms of carbon united together,
and combined, the one with H³, the second with O and OH.
It is thus formed of a group CH³ united to a group CO-OH
CO H. There exist many other acids analogous to acetic
acid, and derived, like it, by oxidation of the monatomic alco-
hols of the series CnH2n+¹OH. All of these acids contain
a hydrocarbon group analogous to methyl, combined with the
group CO¹H = CO-OH. The hydrogen of the latter group
can be readily replaced by an equivalent quantity of metal.
This hydrogen is said to be strongly basic, and all of the organic
acids which contain a single group, CO'H, united to a hydro-
carbon group, are monobasic like acetic acid. The homologues
of the latter form the following series :
MONATOMIC COMPOUNDS.
419
C H2 02
C2 H4 02
C3 116 02
C4 118 02
H -CO2H formic acid.
C H³ -CO2H acetic acid.
C2H5 -CO2H propionic acid.
C3117-CO2H butyric acid.
C+H9 -CO²II valeric acid.
C5II-CO2H caproic acid.
C6H13-CO2H enanthic acid.
C7H15-CO2H caprylic acid.
C5 II1902
C6 II1202
C7 H1402
CS H1602
C9 H1802
C8H17-CO2 pelargonic acid.
C10 H2002
C9H119-CO2H capric acid, etc.
The first series of formulæ indicates simply the nature and
number of atoms contained in the acids of the series CnH2O.
They are empirical formulæ. The second series gives certain
indications upon the relations existing between these atoms.
They are rational formulæ, and when developed so as to ex-
press the relations between all of the atoms, they become
constitutional formulæ.
Compound Ethers. The compound ethers are combina-
tions which represent acids of which the hydrogen has been
replaced by an alcoholic group.
If one of the alcohols of the preceding series, ordinary alco-
hol, for example, be heated for a long time with acetic acid,
water will be formed, and a volatile, neutral liquid possessing an
agreeable odor may be separated from the product; this sub-
stance is ethyl acetate, or acetic ether. It is formed according
to the following reaction:
C²H³.OH + C²H³0.OH
Alcohol.
Acetic acid.
C²H³O¿C²H³O) + H³O
Ethyl acetate.
On comparing this compound with alcohol, we find that it
is formed by substitution of the group C'H³O, the existence of
which is admitted in acetic acid, and which is called acetyl,
for one atom of hydrogen in alcohol; and this atom of hydro-
gen which is replaceable by acetyl is that which is united to the
oxygen in alcohol,-that which forms a part of the hydroxyl
group. The other atoms of hydrogen, those which constitute
part of the group C'H³, cannot be replaced by acetyl.
All of the acids can form with alcohol, and indeed with all
of the alcohols, compounds analogous to ethyl acetate, and
these combinations are called compound ethers. The property
possessed by the alcohols of etherifying acids is general and
characteristic of this class of compounds. Alcohols which
require for etherification but a single molecule of an acid anal-
420
ELEMENTS OF MODERN CHEMISTRY.
ogous to acetic acid are called monatomic. Many exist which
are not included in the preceding series.
Aldehydes. Acetic acid is not the only product of the
oxidation of alcohol. There is another compound interme-
diate between these two; it results from the action of a single
atom of oxygen upon the molecule of alcohol, which thus loses
two atoms of hydrogen without other change. The new com-
pound is aldehyde.
C²H°O + 0 H2O + C²H¹O
Alcohol.
Aldehyde.
It is a very volatile liquid having a great tendency to become
oxidized and converted into acetic acid. It forms crystalline
combinations with the alkaline acid-sulphites. To the other
alcohols of the series CnH2n+20, and other acids of the series
CnH2O2, correspond compounds analogous to aldehyde by their
composition and by their properties. They form the following
series:
aldehyde or acetaldehyde.
propionic aldehyde.
C2H4O
C3H6O
C4H8O
butyric aldehyde.
C5H100
valeric aldehyde, etc.
Acetones. When calcium acetate is submitted to dry distil-
lation a neutral, volatile liquid is obtained, having a peculiar
aromatic odor, and known by the name acetone.
S C²H³O²
C2H3O2
Ca" { CH³O²
Calcium acetate.
C³HO + CaCO³
Acetone.
Calcium carbonate,
To the other acids of the acetic acid scries correspond bodies
analogous to acetone, and forming with it a homologous series.
These acetones are related by properties and composition to the
aldehydes. Like the latter, they form crystalline combinations
with the alkaline acid-sulphites. It may be considered that
while aldehyde is the hydride of acetyl, acetone is the methyl-
ide of acetyl, and that in general the acetones are derived by
the substitution of an alcoholic group, analogous to methyl, for
an atom of hydrogen in the aldehydes considered as hydrides.
CH3_CO_H
Aldehyde (acetyl hydride).
CH3-CO-CH
Acetone (acetyl methylide).
Hence, acetone contains two methyl groups united to a group,
CO (carbonyl). Its mode of formation justifies this conclusion,
MONATOMIC COMPOUNDS.
421
as shown in the following equation, in which the constitutional
formula of acetic acid is employed :
CaCO3 + CH3-CO-CH
CH3–CO.O
CH3_CO.O
Ca
Calcium acetate.
Calcium carbonate.
Acetone.
3
Chlorides of Acid Radicals. In the preceding compounds
we have admitted the existence of a group, C'H³O — CH³-CO,
existing in combination with OH in acetic acid, C'H³O.OH,
with hydrogen in aldehyde, CHO.H, and with methyl in ace-
tone, C²H³Õ.CH³. A compound is known in which this same
group is united with chlorine. Acetyl chloride, C'H³O.Cl, is
a monatomic chloride, like ethyl chloride, CH5Cl, from which
it is distinguished by the strongly electro-negative nature of
its radical.
If acetyl chloride be poured into water, it disappears in a
short time with development of heat and the formation of acetic
and hydrochloric acids.
C²H³O.Cl + H³O
Acetyl chloride.
C²H³O.OH + HCl
Acetic acid.
To acetyl chloride correspond other chlorides which contain
radicals of acids analogous to acetic acid. When they are
treated with water they yield hydrochloric acid and the acids
corresponding to their radicals.
Amides.
CH5O.Cl
Propionyl chloride.
CH'O.Cl
Butyryl chloride.
C'H'O.Cl
Benzoyl chloride.
C³H O.OH
Propionic acid.
C⭑H'O.OH
Butyric acid.
C'H5O.OH
Benzoic acid.
If acetyl chloride be treated with ammonia, am-
monium chloride will be formed, together with a solid, neutral,
nitrogenized body called acetamide.
C2H5O.CI + 2NH³
Acetyl chloride.
NH*C1 + CHO.NH
Acetamide.
There are many other compounds similar to acetamide, and
known by the name amides. They are formed by the action
of ammonia upon organic chlorides analogous to acetyl chloride.
They are also formed by the action of heat upon the ammo-
niacal salts of the monobasic acids. The latter compounds
then lose one molecule of water, and are converted into amides.
CH9O.ON H+ CHO.NH + HO
+
Ammonium valerate.
Valeramide.
36
422
ELEMENTS OF MODERN CHEMISTRY.
Acetamide may be regarded as ammonia in which an atom
of hydrogen has been replaced by the radical acetyl.
H
NH
S
C2H3O
NH
H
H
Acetamide.
C5H⁹O
NH
H
Valeramide.
Ammonia.
Compound Ammonias, or Amines. If ethyl iodide bet
heated with ammonia, one of the products of the reaction will
be the hydriodide of a base derived from ammonia by the sub-
stitution of an ethyl group for an atom of hydrogen.
C²H³I +
Ethyl iodide.
+ NH³
( C²H³)NH².HI
Ethylamine hydriodide.
In this reaction, other ethylated bases are formed, independ-
ently of ethylamine, among which must be mentioned diethyl-
amine and triethylamine. All present the most striking anal-
ogy to ammonia. They may be regarded as ammonia in which
one, two, or three atoms of hydrogen have been replaced by
one, two, or three ethyl groups.
H
HN
H
C2H5
H N
H
Ethylamine.
C²H³
C2H5 N
H
Diethylamine.
C2H5
CH³ N
C2H5
Triethylamine.
Ammonia.
The
The other alcoholic groups, CnH2n+1, can in the same man-
ncr replace one or more atoms of hydrogen in ammonia.
results are bases having constitutions analogous to those of the
ethyl bases. They are called amines, or compound ammonias.
It is necessary that the signification of the formulæ above
given and those that are to follow shall be clearly understood.
They are examples of typical notation, and indicate the rela-
tions of the compounds with the type ammonia.
N'" SH
H
The brace joining the three hydrogen atoms signifies that
the whole three are united to a single atom of triatomic nitro-
gen, with which each exchanges one atomicity; this may be
expressed by writing the formula for ammonia thus:
H
N"--H
H
MONATOMIC COMPOUNDS.
423
What, then, takes place when one or more atoms of hydro-
gen are replaced by a group like ethyl? The latter exchanges
one atomicity with the nitrogen atom, precisely as the hydro-
gen atom did, and combines with the nitrogen by one of the
atoms of carbon of the group ethyl, CH3-CH", which requires
the satisfaction of one atomicity.
This is clearly expressed in the following graphic formulæ :
H
N-CH2-CH³
H
N-CH2-CH³
CH2-CH³
3
Ethylamine.
Diethylamine.
However, such formulæ would be too cumbrous for ordinary
use, and our formulæ must be more condensed.
C2H5
N H
H
C2H5
C2H5
H
Diethylamine.
N(C²H³¸³
3
Triethylamine.
Ethylamine.
Phosphines. Arsines. Stibines.-There exist several se-
ries of combinations belonging to the same type as the com-
pound ammonias, but in which the nitrogen is replaced by
phosphorus, arsenic, or antimony. These compounds are de-
rived from the hydrogen compounds of phosphorus, arsenic,
and antimony by the substitution of one or more alcoholic
groups for one or more atoms of hydrogen.
H
HP
H
Hydrogen phosphide. Ethylphosphine. Diethylphosphine.
C2H5
C2H5 P
C2H5
Triethylphosphine.
C2H5
H P
H
C2H5
C2H5 P
H
H
HAs
H
CH³
CH3
CH3
H As
H
Hydrogen arsenide. Methylarsine.
CH As
Cl
Dimethylarsine
chloride.
CH As
CH³
Trimethylarsine.
H
H Sb
H
Hydrogen antimonide.
C2H5
C2H5 Sb
C2H5
Triethylstibine.
Organo-metallic Compounds.-Ethyl and its congeneric
compounds, methyl, amyl, etc., can enter into combination not
only with nitrogen, phosphorus, arsenic, etc., of which they
saturate one or more atomicities, but with a large number of
424
ELEMENTS OF MODERN CHEMISTRY.
metals.
Thus, zinc, which is diatomic, can combine with two
ethyl groups to form zinc ethyl.
Zn
{
C2H5
C2H5
Mercury, also diatomic, can unite with one or two ethyl or
methyl groups, etc. In the second case, the new combination
is saturated; in the first, it is monatomic, (Hg"CH³)', and re-
quires for saturation an atom of a monatomic element, or a
monatomic group, iodine, for example.
C2H5
Hg" { CH³
ᏟᎻ
Mercur-ethyl.
S C2H5
Ι
Hg" {I
Mercur-monethyl iodide.
Bismuth, which is triatomic, can fix three ethyl groups.
C2H5
Bi""
C2H5
C2H5
Bismuth-ethyl.
Stanno-tetrethyl is formed by the union of four ethyl groups
with one atom of tetratomic tin.
C2H5
C2H5
Sniv
C2H5
C2H5
If the four atomicities of tin be not all satisfied, non-satu-
rated compounds may be formed.
Sn"
Į
C2H5
C2H³
Stanno-diethyl.
C2H5
-Sniv C2H5 or -Sniv-C2H5
C2H5
Stanno-triethyl.
C2H5
C2H5
Stanno-diethyl is known in the free state, but stanno-triethyl
doubles its molecule as soon as it is set at liberty, combining
with itself, as it can combine with iodine.
ISniv (C2H5,3
Stanno-triethyl iodide.
3
(C2H³ ³Sniv-Sniv(C2H5) Sn²(C2H5).
Sesquistannethyl.
Non-saturated compounds are apt to combine with other
elements or radicals. Stanno-tetrethyl, which is saturated, does
not possess this faculty.
The bodies just mentioned belong to the class of organo-
metallic compounds. Their study is of great importance in
the history of the atomicity of the metals, that is, their power
of saturation. The theoretical considerations concerning them
have been discussed by Frankland, Baeyer, and Cahours.
MONATOMIC RADICALS.
425
Monatomic Radicals. From the preceding summary may
be understood the position occupied in organic chemistry by
certain groups containing carbon, groups that are distinguished
as monatomic because they can manifest but a single atomicity.
Only a single monatomic atom or group is wanting that all of
the carbon atoms contained in these groups may be entirely
saturated. These groups of atoms or radicals cannot exist in
the state of liberty, but they can pass from one compound to
another, replacing a single atom of hydrogen or other mon-
atomic element, and consequently playing the part of that ele-
ment in the new combination. This is expressed by saying
that these groups act as monatomic radicals.
To indicate the constitution of the combinations containing
such groups, and especially the metamorphoses that they may
undergo by exchanging these radicals by double decomposition,
it is convenient to distinguish the latter by unique expressions,
occupying a place in the formula distinct from that of the
other elements. The composition of all of the bodies which
have just been reviewed may be represented by very simple.
formulæ, by comparing them to hydrogen compounds, such as
free hydrogen, or hydrochloric acid, water, and ammonia. The
notation then assumes a typical form, exceedingly clear for the
interpretation of the majority of reactions.
The following are the typical formulæ for the combinations
that have been considered:
TYPE HH.
(C²H³)CI
Ethyl chloride.
(C²H³O)Cl
Acetyl chloride.
(C2H³O)H
Aldehyde.
(C²H³O)(CH³)
Acetone.
TYPE}
0.
H
TYPE HN.
H
(C2H5
(C2H³)
}} 0
H
Ethyl hydrate.
(C² H³)
(C²H³)
}
O
Ethyl oxide.
(C²H³O) }
} 0
H
Acetic acid.
(CH*O)}
(CH) J
Ethyl acetate.
HN
H
Ethylamine.
(C²H³)
(C²H³) N
H
Diethylamine.
(C2H5)
(C2H5) N
(C2H³)
Triethylamine.
(C² H³O)
HN
H
Acetamide.
36*
426
ELEMENTS OF MODERN CHEMISTRY.
POLYATOMIC COMPOUNDS.
If chlorine and olefiant gas, or ethylene, be mixed in equal
volumes, both gases disappear and are converted into an oily
substance, which was formerly called Dutch liquid. This body
results from the combination of a molecule of ethylene with a
molecule (two atoms) of chlorine. It is ethylene chloride.
C²H¹ + Cl²
Ethylene.
C2H+C12
Ethylene chloride.
If the constitution of ethylene gas, C2H4, be compared with
that of the saturated hydrocarbon ethane, CH, which like the
former contains two atoms of carbon, it will be noticed that it
contains two atoms of hydrogen less.
C2H6 - H2 C²H¹
In ethylene the six atomicities of the pair of carbon atoms
are not saturated. Hence that gas can absorb directly two
atoms of chlorine, bromine, or iodine to form a saturated com-
pound.
H H
H-C-C-H
H H
-C-C-
1
1
H H
Ethane.
H H
Ethylene.
H H
Cl-C-C-CI
H H
Ethylene chloride.
It is a diatomic radical, and it can exist in the free state
because until other atoms are presented to satisfy the atom-
icities of the two atoms of carbon, those two atoms are bound
together by a double affinity. Thus, HC-CH². One of
these bonds is loosed when the ethylene manifests its affinities
and enters directly into combination, because the affinity of
carbon for chlorine or such an element is greatcr than its
affinity for carbon Ethylene is the first of a numerous class.
The following bodies form with it the homologous series CnH2":
C2H4 ethylene.
C3116 propylene.
C4H8 butylene.
C51110 amylene.
C6H12 hexylene.
C7H14 heptylene.
C81116 octylene.
C9H18 nonylene.
C10H120 decylene, etc.
POLYATOMIC COMPOUNDS.
427
All of these bodies are able to fix directly two atoms of
chlorine or bromine. When they enter into combination, they
take the place of two atoms of hydrogen. They can pass by
double decomposition from one compound to another, and their
combinations may undergo various metamorphoses analogous
to those already indicated.
Diatomic Alcohols or Glycols.-The glycols are compounds.
in which the two atomicities of the diatomic radicals are saturated
by two hydroxyl groups. The two atoms of bromine in ethy-
lene bromide, CH Br", may be replaced by two hydroxyl groups
(OH), and the resulting combination is ethylene dihydrate.
Br
C²H¹<
-Br
OH
CH<OH
The two atoms of hydrogen united to the oxygen in the
hydroxyl groups in glycol may both be replaced by acid radi-
cals analogous to acetyl, just as the single atom of hydrogen in
the single hydroxyl group of a monatomic alcohol may be
replaced by an acid radical. This is characteristic of a diatomic
alcohol.
To ethylene dihydrate, or ordinary glycol, correspond the
hydrates of the other hydrocarbons homologous with ethylene.
The following glycols are known :
C²H± {
OH glycol.
он
C³II6 OH propylglycol.
он
OII
C4118
{ butylglycol.
OH
JOH
он
C5H10OH amylglycol.
он
(OH
OH
C6II12 hexylglycol, etc.
Around each of these bodies are grouped a great number of
derivatives, among which we can only consider the ethers, acids,
and compound ammonias.
Ethers of the Glycols. The ethers of the glycols result
from the substitution of alcoholic or acid radicals for the hydro-
gen of the groups OH.
OH. One or both of these hydrogens may
be thus replaced, and the following examples will illustrate the
constitution of the compounds so formed:
C²II+ OH
O.C2H5
Monethylic glycol.
O.C2H5
C² H+ {O.C2H5
Diethylic glycol.
O.C2H3O
C2H+
| OH
Glycol monacetate.
·C2II+
[ O.C2H30
{
O.C2H3O
Glycol diacetate.
428
ELEMENTS OF MODERN CHEMISTRY.
Diatomic and Dibasic Acids.-Diatomic acids result from
the oxidation of the glycols. Their formation and constitu-
tion may be understood by developing the formulæ of the
hydrocarbons which constitute the radicals of these glycols.
Ordinary glycol may yield two acids by oxidation, the first
resulting from the substitution of an atom of oxygen for two
atoms of hydrogen, the second from the substitution of two
atoms of oxygen for four atoms of hydrogen. The following
formulæ express the constitution and derivation of these com-
pounds:
CH2
CH2
CH2 Br
CH2.OH
CH2.OH
CHⓇBr
CH2OH CO.OH
Glycollic acid.
CO.OH
CO.OH
Oxalic acid.
Ethylene. Ethylene bromide. Glycol.
Glycollic and oxalic acids, which are produced by the oxida-
tion of glycol, are both diatomic because they are both derived
from a diatomic alcohol; but the first is monobasic because it
contains but a single atom of hydrogen that can be replaced by
a metal. The second is dibasic, for it contains two atoms of
hydrogen that are replaceable by an equivalent quantity of metal.
This basic hydrogen is that which forms part of the group
CO*H. Oxalic acid is composed simply of two groups -CO³H ;
it is dibasic. Glycollic acid contains but one, and it is conse-
quently monobasic. The hydrogen united to the oxygen in
the group -CH2.OH is called alcoholic hydrogen; it may be
replaced by an acid radical, but it cannot be easily replaced by
a metal. All bodies containing a group CH2.OH are alcohols,
and all bodies containing a group CO.OH are acids. The
alcohols and acids are thus defined by their constitution. Gly-
collic acid is at the same time an alcohol and an acid, for it
contains both a group CH2.OH and a group CO.OH.
There exists a series of acids homologous with glycollic acid,
and another series homologous with oxalic acid. Both series
appertain to the superior diatomic alcohols.
Diatomic Ammonias or Diamines.-Compounds exist
which hold the same relation to the diatomic alcohols as ethyl-
amine and its homologues to the monatomic alcohols. Such
a compound is ethylene-diamine. Its relations with ethylene
chloride and glycol are expressed by the following formula:
Cl
C² H+ Cl
Ethylene chloride.
OH
C2H+
OH
Glycol.
C2H+
NH2
NH2
Ethylene-diamine.
CYANOGEN.
429
Alcohols of Higher Atomicity. There are alcohols of
higher atomicity; glycerin, for example, is a triatomic alco-
hol. It contains a radical, CH", which is triatomic since it is
derived from the saturated hydrocarbon CH³, by the subtrac-
tion of three atoms of hydrogen. Erythrite is a tetratomic
alcohol; it contains the tetratomic radical C'H' -- C¹H¹º —H¹.
Lastly, the sweet, sugar-like substance derived from manna
and known as mannite is a hexatomic alcohol. There are
numerous similar substances which are alcohols of higher
atomicity. The following formulæ express the composition
and the functions of these polyatomic alcohols:
C3H5OH
JOH
OH
OH
C4H6iv
OH
C6H8Ti(OH)
6
OH
OH
Erythrite.
Mannite.
Glycerin.
Around these bodies are grouped the numerous correspond-
ing derivatives, ethers, acids, etc.
It will be seen by the preceding considerations that the neu-
tral hydrates, called alcohols, are highly important in them-
selves and on account of the derivatives which attach to them.
Hence the elements of a natural classification of organic com-
pounds are deduced.
COMPOUNDS OF CYANOGEN.
Gay-Lussac gave the name cyanogen to the radical of prussic
or hydrocyanic acid, which was discovered by Scheele in 1782.
This radical is composed of one atom of carbon and one atom of
nitrogen. In hydrocyanic acid it is united with hydrogen; in
the cyanides it is combined with the metals.
H(CN)
Hydrocyanic acid.
K(CN)
Potassium cyanide.
Hg"(CN)2
Mercury cyanide.
The preceding compounds may be compared with the corre-
sponding chlorides:
HCI
Hydrochloric acid.
KCI
Potassium chloride.
HgCl2
Mercuric chloride.
It is somewhat remarkable that potassium cyanide is iso-
morphous with potassium chloride.
In the preceding compounds, cyanogen, which is composed of
an atom of carbon and an atom of nitrogen, plays a part anal-
ogous to that of chlorine. It is a monatomic radical; nitrogen,
430
ELEMENTS OF MODERN CHEMISTRY.
which is triatomic, can saturate only three of the four atomici-
ties which reside in an atom of carbon. Hence there remains
one free atomicity, and cyanogen can act as a monatomic radi-
cal, −C=N.
CYANOGEN.
(CN)² = Cy²
Preparation. Mercury cyanide is heated in a small retort
fitted with a delivery-tube. The mercury volatilizes, and a gas
is disengaged which may be collected over mercury.
There
remains in the retort a solid brown mass which possesses the
same composition as cyanogen, and is known as paracyanogen.
Hg(CN)² = (CN)2+ Hg.
Composition and Properties.-Cyanogen is a colorless gas,
possessing a strong odor of bitter almonds. It may be easily
liquefied by a pressure of 4 atmospheres or a temperature of
-25° Its density is 1.8064 compared to air, or 26 compared
to hydrogen. This is free cyanogen.
It has separated from the mercury, which is condensed in
little drops in the dome of the retort.
The atom of mercury
was combined with two groups (CN), which unite together
when they separate from the mercury, and remain combined
together in the gas which is disengaged. The latter contains
CN combined with CN. Its formula is:
NC-CN
(CN)² -- Cy²
2 volumes of this gas contain two atoms of carbon and two
atoms of nitrogen.
This composition may be demonstrated by eudiometric analy-
sis.
2 volumes of cyanogen and 4 volumes of oxygen are intro-
duced into a mercury eudiometer. On the passage of an electric
spark there is a flash of blue light, and the volume of the gas
is not changed. If a solution of potassium hydrate be now
passed into the eudiometer, the six volumes of gas will be
reduced to two.
4 volumes of CO2 are formed;
2 volumes of N remain.
2 volumes of cyanogen then contain the carbon contained in 2002, that
is, C², and N².
This is expressed by saying that the formula of cyanogen, C²N² —- Cy²,
corresponds to 2 volumes.
HYDROCYANIC ACID.
431
On contact with flame, cyanogen takes fire and burns in the
air with a purple flame, yielding carbon dioxide and nitrogen.
Water dissolves four and one-half times its volume of cyan-
ogen. When this solution is left to itself it deposits brown
flakes. It then contains in solution urea, ammonium carbonate,
ammonium cyanide, and ammonium oxalate.
C2N2 + H2O (NH')CO
Cyanogen.
C2N2 + H2O
Ammonium oxalate.
HCN +
CO
N
H
Cyanogen.
Hydrocyanic acid.
Cyanic acid.
CO
HN + HO
CO
+ NH³
Ammonia.
Cyanic acid.
The ammonia formed by the latter reaction combines with
the cyanic acid to form ammonium cyanate, which becomes
converted into urea, as will be seen shortly.
It is a curious fact that in the presence of a small quantity
of aldehyde, the decomposition of an aqueous solution of
cyanogen yields, almost entirely, but one product,-oxamide.
C²N² + 2H2O
NH2
C²O²
NH2
Oxamide.
If a fragment of potassium be heated in cyanogen gas, a
brilliant flash of light takes place; in combining with cyanogen
potassium becomes incandescent. Potassium cyanide is formed.
(CN)² + K² = 2KCN
In this reaction, cyanogen combines directly with a metal.
It acts as a simple element, such as chlorine.
Paracyanogen, which has been mentioned before, is a poly-
meride of cyanogen. When it is quickly heated to redness, it
is entirely transformed into cyanogen gas.
HYDROCYANIC ACID.
(PRUSSIC ACID.)
HCN HCy
Preparation.-Gay-Lussac prepared hydrocyanic acid by
heating mercury cyanide with hydrochloric acid.
An easier process consists in decomposing prussiate of potash
(potassium ferrocyanide) with sulphuric acid. 8 parts of the
432
ELEMENTS OF MODERN CHEMISTRY.
salt in fine powder are heated in a retort with 9 parts of sul-
phuric acid, previously diluted with 14 parts of water.
The neck of the retort is inclined upwards, so that the aque-
ous vapors are condensed and run back into the retort, while
the vapor of prussic acid, which is very volatile, is dried by
passage through a tube containing calcium chloride, and con-
densed in a receiver placed in a freezing mixture of ice and
salt.
Properties. This acid is a colorless, limpid, and very vol-
atile liquid, having a penetrating odor resembling that of bitter
almonds. Its density at 7° is 0.7058. It boils at 26.5°, and
solidifies to a crystalline mass at —15°.
It scarcely reddens blue litmus-paper. On contact with an
incandescent body, it takes fire and burns with a white flame
lightly tinted with violet.
It does not keep long in the pure state. It becomes brown,
and is finally converted into a solid, brown mass.
It dissolves in water in all proportions. A solution contain-
ing 2 per cent. is used in medicine.
When hydrocyanic acid is mixed with its own volume of
concentrated hydrochloric acid, the mixture gets hot and soon
deposits abundant crystals of ammonium chloride. The solu-
tion contains formic acid.
HCN + 2H2O
Hydrocyanic acid.
CH’O + NH3
Formic acid.
In reactions with the hydracids, hydrocyanic acid can function
like a compound ammonia, N(CH)" (formonitrile). It unites
with elevation of temperature with hydrochloric, hydrobromic,
and hydriodic acids to form compounds, such as N(CH)".
HCl and N(CH)"".HI, that may be compared to the ammo-
nium salts. In these crystalline compounds, the anhydrous.
bases can displace the hydrocyanic acid, as they displace am-
monia in the ammoniacal salts; thus,
N(CH)HCl + NH* = NH*Cl + HƠN
Cupric oxide displaces hydrocyanic acid in the same manner
in the hydrobromide of formonitrile.
The oxidized organic acids unite only with difficulty with
hydrocyanic acid, and at an elevated temperature (Arm.
Gautier).
Hydrocyanic acid is one of the most rapid and most danger-
ous of poisons. A single drop placed upon the eye of a rabbit
METALLIC CYANIDES.
433
is sufficient to kill the animal in a few instants, and after vio-
lent convulsions.
Hydrocyanic acid may be detected by the following tests:
1. It gives a white precipitate of silver cyanide with silver
nitrate, and this precipitate does not darken on exposure to
light. When properly dried and heated, silver cyanide disen-
gages cyanogen.
2. If a drop of hydrocyanic acid be added to a mixed solu-
tion of ferrous and ferric sulphates, and an excess of potassium
hydrate be added, a thick, dark-colored precipitate is formed.
If this be treated with an excess of hydrochloric acid, the fer-
rous and ferric oxides precipitated will be dissolved, and Prus-
sian blue will remain, strongly coloring the liquid.
METALLIC CYANIDES.
We will only consider the two more important metallic cya-
nides, those of potassium and mercury.
Potassium Cyanide, KCy KCN.-This compound is
prepared by heating well-dried potassium ferrocyanide to red-
ness in stoneware retorts. After cooling, the black mass is
exhausted with alcohol; this solvent leaves a black deposit,
consisting of charcoal and iron, and the solution evaporated in
vacuo deposits the potassium cyanide as a white, crystalline
mass.
This body crystallizes in cubes. It has a caustic taste and
an after-taste of bitter almonds. It is very poisonous. It is
quite soluble in water and alcohol. When its aqueous solution
is boiled, it disengages ammonia, and is converted into potas-
sium formate. This reaction takes place slowly in the cold,
and is analogous to that which has before been described.
When potassium cyanide is heated with sulphur, it is con-
verted into potassium sulphocyanate. Iodine dissolves abun-
dantly in a solution of potassium cyanide; potassium iodide is
formed, and cyanogen iodide is deposited in crystals.
Solution of potassium cyanide dissolves the insoluble cya-
nides of zinc, silver, etc., forming double cyanides.
Mercury Cyanide, HgCy Hg(CN). This compound
is prepared by dissolving finely-powdered mercuric oxide in an
aqueous solution of hydrocyanic acid until the odor of the lat-
ter has entirely disappeared, being careful to avoid an excess
of the oxide. After concentration and cooling, colorless, anhy-
T
37
434
ELEMENTS OF MODERN CHEMISTRY.
drous prisms are obtained, which are unaltered by air and light.
This is mercury cyanide. It is very poisonous.
It possesses a nauseous metallic taste, and dissolves in 8
parts of cold water.
It is decomposed by heat into mercury and cyanogen; para-
cyanogen is formed at the same time. The solution of mer-
cury cyanide dissolves mercuric oxide, and forms with it a
compound more soluble than the cyanide, crystallizing in color-
less scales.
If a solution of potassium iodide be added to a solution of
mercuric cyanide, a compound of the two substances is imme-
diately precipitated in beautiful pearly scales (Cailliot).
FERROCYANIDES.
By this name are designated compounds containing cyanogen
and iron intimately combined together and forming a complex
radical capable of passing from one compound to another by
double decomposition. This radical, which is called ferrocy-
anogen, contains one atom of diatomic iron combined with six
cyanogen groups, CN. As each of the latter represents one
atomicity, it is evident that the group (Cy-Fejiv, in which
but two atomicities are saturated between the Fe and 20y,
must be tetratomic. Hence ferrocyanogen can combine with
four atoms of a monatomic metal such as potassium. The im-
portant compound known as potassium ferrocyanide, or yellow
prussiate of potash, has such a composition.
Potassium Ferrocyanide, K'CyºFe + 3H20.—This salt is
obtained by calcining animal matters, such as blood, horn, the
débris of skin, leather, etc., in closed iron vessels with potassium
carbonate. The calcined mass, which contains potassium cy-
anide, is exhausted with boiling water, and ferrous sulphate is
added to the solution, which is then evaporated to crystalliza-
tion; or the solution is boiled with metallic iron, which dissolves
with evolution of hydrogen. The iron may also be added to
the mixture of animal matter and potassium carbonate before
calcination; after cooling, the mass is pulverized and exhausted
with boiling water. The solution contains ferrocyanide.
When sufficiently concentrated, it deposits the salt in yellow
crystals, which are derived from a square octahedron. They
are unaltered by the air, but lose 12.8 per cent. of water at
100°. The anhydrous salt is white.
POTASSIUM FERRICYANIDE.
435
Potassium ferrocyanide dissolves in 2 parts of boiling, and
in 4 parts of cold water. It is insoluble in alcohol. When
heated with bodies rich in oxygen, such as manganese dioxide,
it is converted into potassium cyanate, the iron itself being
oxidized to peroxide. It is not poisonous.
When fused with sulphur, it is converted into potassium.
sulphocyanate.
When heated with concentrated sulphuric acid, it yields pure
carbon monoxide, and a residue consisting of sulphates of iron,
potassium, and ammonium.
Potassium ferrocyanide precipitates many metallic solutions.
The following are some of these precipitates:
white.
Zinc ferrocyanide
Copper ferrocyanide
Lead ferrocyanide
Silver ferrocyanide
Zn²Cy6Fe,
Cu²Cy6Fe,
Ph2Cy6Fe,
Ag+CyFe,
mahogany color.
white.
white.
Potassium ferrocyanide forms a bluish-white precipitate with .
ferrous salts. This precipitate contains:
Fe"
Cy°Fe
Cy Fe { K²
K2
It is identical with the bluish-white deposit which is formed when
potassium ferrocyanide is heated with dilute sulphuric acid.
Prussian Blue, (Fe²)2(CyFe).-This is the dark-blue pre-
cipitate obtained when a solution of potassium ferrocyanide is
poured into a ferric salt.
- 12KCI +
2Fe2C16+ 3K+CyFe
Ferric chloride. Potassium ferrocyanide.
+
Fe¹(Cy‘Fe)³
Ferric ferrocyanide.
(Prussian blue.)
The Prussian blue of commerce ordinarily occurs in cubical
fragments, having a fine blue color and a coppery reflection.
When calcined in contact with the air, it leaves a residue
of peroxide of iron. It is insoluble in water, alcohol, and in
the weaker acids. Oxalic acid dissolves it, and the solution is
employed as a blue ink.
POTASSIUM FERRICYANIDE.
(RED PRUSSIATE OF POTASII.)
K(Cy6Fe)2
This beautiful salt, discovered by Leopold Gmelin, is formed
when a current of chlorine is passed into a solution of potassium
ferrocyanide. Potassium chloride and potassium ferricyanide
are formed, and the latter gives to the liquid a deep green-brown
436
ELEMENTS OF MODERN CHEMISTRY.
color. On evaporation it deposits the new salt, which is puri-
fied by a second crystallization. Potassium chloride remains
in the mother-liquor.
2K¹(Cy°Fe) + C1²
Potassium ferrocyanide.
2KCl + K(CyFe)"
Potassium ferricyanide.
Potassium ferricyanide forms magnificent clinorhombic prisms
of a ruby-red color. These crystals are anhydrous. They con-
tain K Cy12Fe. It is considered that they contain a hexad
radical, Cy¹Fe², formed by the union of two ferrocyanogen
radicals (FeCy-CyFe)vi ferricyanogen.
Potassium ferricyanide dissolves in 3.8 parts of cold water,
and in a less quantity of boiling water. The solution has a
dark yellow-brown color. It does not precipitate the ferric
salts. In solutions of the ferrous salts it gives a blue precip-
itate analogous to Prussian blue, and which is called Turnbull's
blue.
K(CyFe) + 3FeSO¹
Potassium
, ferricyanide.
Ferrous sulphate.
3K SO+ Fe³(Cy Fe)2
Potassium
sulphate.
NITROFERROCYANIDES.
Ferrous ferricyanide.
(Turnbull's blue.)
These salts, which were discovered by Playfair, are formed
by the action of nitric acid upon certain alkaline ferrocyanides.
The best known is sodium nitroferrocyanide, or, as it is ordi-
narily called, sodium nitroprusside.
It is prepared by oxidizing potassium ferrocyanide with dilute
nitric acid. After filtration and evaporation, crystals of potas-
sium nitrate and a deposit of oxamide are obtained. The
mother-liquor is saturated with sodium carbonate, and on
evaporation yields sodium nitroprusside, which may be purified
by recrystallization.
Sodium nitroferrocyanide crystallizes in large right rhombic
prisms of a ruby-red color. Its composition is represented by
the formula Na²Cy³(NO)Fe + 2H²Ô. Its aqueous solution
has a red-brown color, and gives a very intense but evanescent
purple color with solutions of the alkaline sulphides.
CHLORIDES OF CYANOGEN.
There are two chlorides of cyanogen known, a chloride,
CyCl, which is liquid below 15.5°, and a solid chloride, Cy³CP³.
These two chlorides present a curious instance of polymerism.
CHLORIDES OF CYANOGEN.
437
Liquid Cyanogen Chloride, CyCl CNCI. This com-
pound is prepared by passing chlorine gas over mercury cy-
anide, or better, into an aqueous solution of hydrocyanic acid,
which is maintained at 0°. Hydrochloric acid and cyanogen
chloride are formed.
HCN + Cl2 CNCI + HCI
When the solution is saturated with chlorine, it is gently
heated, and the cyanogen chloride which is disengaged is
passed through a tube containing calcium chloride, and con-
densed in a well-cooled receiver.
When properly purified, cyanogen chloride is a colorless
liquid, having a penetrating odor, which is very irritating to
the eyes. It boils at 15.5° and solidifies at
It boils at 15.5° and solidifies at -5 or -6°. When
pure, it can be preserved without alteration, but if it contain a
trace of chlorine, it soon becomes converted into the solid
chloride.
Solid Cyanogen Chloride, Cy³CP CN³CP.-This body
results from the polymeric transformation which the liquid
chloride undergoes spontaneously under certain circumstances.
It can also be obtained by exposing hydrocyanic acid to the
action of chlorine in direct sunlight.
It crystallizes in brilliant, yellow needles or plates. It melts
at 140° and boils at 190°. It has a peculiar, irritating odor.
Boiling water immediately decomposes it into hydrochloric and
cyanuric acids.
C3N3C13 + 3H20
Cyanogen chloride.
3
(CO) N³ + 3HC1
H3N3+3HC1
H³
Cyanuric acid.
Cyanogen Bromide and Iodide.-The bromide and iodide
of cyanogen correspond in constitution to the liquid chloride.
They are obtained by the action of bromine or iodine upon
mercury cyanide. These elements decompose mercury cyanide
with formation of bromide or iodide of mercury, the excess
of bromine or iodine combining with the cyanogen to form
cyanogen bromide or iodide.
Cyanogen bromide, CNBr, is solid and crystallizes in bril-
liant cubes. It melts at 4° and vaporizes at 15°.
Cyanogen iodide, CNI, sublimes spontaneously in beautiful
colorless needles when a mixture of iodine and mercury cya-
37*
438
ELEMENTS OF MODERN CHEMISTRY.
nide is placed in the bottom of a flask. Mercuric iodide is
formed. Cyanogen iodide has a penetrating odor; it is very
volatile and, like the chloride and bromide, is very poisonous.
COMPOUNDS OF CARBON MONOXIDE.
Carbon monoxide plays the part of a diatomic radical. It is
capable of uniting with one atom of oxygen to form carbonic acid
gas, or with two atoms of chlorine to form chlorocarbonic gas.
It can also unite with two residues, NH2, which are mon-
atomic since they represent ammonia less one atom of hydro-
gen; lastly, it may unite with NH, which is diatomic since it
represents ammonia minus two atoms of hydrogen. The com-
pounds thus formed have the following constitutions:
CO.0
carbon dioxide.
co<l chlorocarbonic gas.
NH2
CO
urea.
NH2
CO(NH)" cyanic acid.
The last two compounds can be considered as derived from
the ammonia type.
Cyanic acid is derived from one molecule of ammonia by
the substitution of the diatomic radical CO, which is called
carbonyl, for two atoms of hydrogen.
H
N
H
H
N
{
CO"
H cyanic acid.
Urea is derived from two molecules of ammonia by the sub-
stitution of the radical carbonyl for two atoms of hydrogen.
H2
N2 H2
H2
CO"
N2
{
H2 urea.
H2
Urea is then carbonic diamide; or more simply, carbamide.
CYANIC ACID.
CONH
Liebig and Wöhler obtained this acid by the dry distillation
of cyanuric acid. One molecule of the latter, which is poly-
meric with cyanic acid, then breaks up into three molecules of
the latter body.
C30³N³H3
Cyanuric acid.
3CONH
Cyanic acid.
CYANIC ACID.
439
The latter acid condenses at a few degrees below 0° to a color-
less liquid having a strong and irritating odor. It is very
unstable. As soon as it is removed from the freezing mixture
in which it is condensed, and its temperature rises to a few
degrees above 0°, it produces a crackling noise and little ex-
plosions, and is converted by a molecular transformation into
an amorphous white mass called cyamelide. The latter body
is also formed at the same time as cyanic acid by the dry distil-
lation of cyanuric acid.
Potassium Cyanate, KCON.-This salt is prepared by
heating to dull redness in a flat sheet-iron dish an intimate
mixture of 2 parts of potassium ferrocyanide and 1 part of
manganese dioxide, both in fine powder and perfectly dry.
The mixture must be continually stirred; it blackens and
enters into semi-fusion; after cooling, it is reduced to powder
and exhausted with hot alcohol of 80 per cent. On cooling,
the filtered alcoholic solution deposits potassium cyanate in
laminated, transparent crystals which are anhydrous. This salt
is very soluble in water and but slightly soluble in cold concen-
trated alcohol. If hydrochloric acid be added to an aqueous so-
lution of potassium cyanate, carbonic acid gas is disengaged with
brisk effervescence. The liquid contains ammonium chloride.
CONH + HẢO = CO + NH
There is a compound isomeric with potassium cyanate; it is
formed by the action of cyanogen chloride upon potassium
hydrate (Bannow).
CN.CI+ 2KOH KCl + H2O + KCNO
Cyanogen chloride.
Potassium cyanate.
The hydrate corresponding to this potassium salt would be
the true cyanic acid, of which the ethers were discovered by
Cloüz. The compound actually known by the name cyanic acid
does not merit that name. It is not a compound of cyanogen,
but a combination of oxide of carbon; it is carbimide. It should
be called isocyanic acid. The following formulæ will explain.
this curious isomerism:
H-O-CEN
Cyanic acid.
K-O-CEN
Potassium cyanate (Bannow).
C2H5-O-CEN
Ethyl cyanate
(Cloëz).
H-N=C=O
Isocyanic acid.
K-N=C=O
Potassium isocyanate (ordinary cyanate).
C²H³-N=C=0
Ethyl isocyanate.
(Cyanic ether of Wurtz.)
440
ELEMENTS OF MODERN CHEMISTRY.
Ammonium Cyanate.-This is formed when vapor of cyanic
acid is passed into a flask containing ammonia gas. It is a solid,
white mass, very soluble in water. When its aqueous solution
is treated with hydrochloric acid, it disengages carbon dioxide.
like the solution of potassium cyanate. If its aqueous solution
be boiled, or even left to itself for several days, ammonium
cyanate becomes transformed into urea.
(NH)CON
Ammonium cyanate.
UREA.
CH+N20
NH2
CO<
NH2
Urea.
This body, noticed by Rouelle in 1773, is the most abundant
of the solid constituents of urine, from which it was extracted
by Foureroy and Vauquelin in 1799. Wöhler was the first to
obtain urea artificially by combining cyanic acid and ammonia.
CONH + NH3 = CH*NO
This discovery was the first instance of the synthesis of an
organic body.
Urea is also formed by the action of chlorocarbonic gas upon
ammonia (Natanson).
Cl
CO
+ 2NH³
-NH2
CO<
NH2 + 2HCI
Also by the action of ammonia on ethyl carbonate.
O.C2H5
CO<O.C2H5 + 2NHI³ CO
Ethyl carbonate.
NH2
NH2
+ 2(C²H³.OH)
Urea.
Alcohol.
These reactions show clearly that urea is the amide corre-
sponding to carbonic acid, that is, carbonic diamide. Indeed,
it represents neutral ammonium carbonate, less two molecules
of water.
co<
O.NH⭑
2H2O
0.NH*
NH2
co<
NH2
Preparation.-1. Urea may be obtained from urine by the
following process. The urine is evaporated to a syrupy consist.
UREA.
441
ence on a water-bath. It is allowed to cool, and an excess of
cold nitric acid is added; a mass of crystals are formed, which
ordinarily have a brown color. They are drained, washed with
a little ice-water, redissolved in hot water, and animal charcoal
which has been washed with hydrochloric acid is added. The
whole is heated on a water-bath for a few minutes and then
filtered. Colorless crystals of urea nitrate are obtained on
cooling.
They are suspended in water, and a concentrated solution
of potassium carbonate is added little by little, until all effer-
vescence ceases. Carbon dioxide is disengaged, and potassium
nitrate is formed, while the urea is set free. The liquor is
evaporated to dryness on the water-bath, and the residue ex-
hausted with absolute alcohol, which dissolves the urea, while
the potassium nitrate remains. The alcoholic solution is con-
centrated, and urea crystallizes out.
2. Potassium cyanate is prepared by heating 28 parts of
well-dried potassium ferrocyanide with 14 parts of manganese
dioxide, as has been already indicated. The cooled mass is
coarsely powdered, and exhausted with cold water, which dis-
solves the potassium cyanate. 20 parts of ammonium sulphate
are added to the filtered liquid, which is then evaporated to
dryness on a water-bath. The residue is exhausted with boil-
ing alcohol, which dissolves the urea and leaves potassium sul-
phate.
In this operation the potassium cyanate and ammonium sul-
phate undergo double decomposition, with formation of potas-
sium sulphate, and ammonium cyanate which is transformed
into urea.
Properties.-Urea separates from its aqueous solution in
long, flattened, and striated prisms. It sometimes deposits
from its alcoholic solution in square prisms.
The crystals are colorless and possess a cooling taste. They
dissolve in their own weight of water at 15°, and in 5 parts
of cold alcohol of specific gravity 0.816. They are but slightly
soluble in ether.
If a solution of urea be added to a concentrated solution of
chloride of lime, there is an abundant disengagement of gas,
which is a mixture of nitrogen and carbon dioxide. The urea
is entirely destroyed.
T*
CH N2O+ H2O+3C12 CO² + N²+6HCI
=
442
ELEMENTS OF MODERN CHEMISTRY.
An aqueous solution of chlorine produces the same decom-
position.
Nitrous anhydride instantly destroys urea, with formation of
water, carbon dioxide, and nitrogen.
CHNO + NO3 CO² + 2H2O + 2N²
When an aqueous solution of urea is heated to 140° in a
sealed tube, it absorbs the elements of water, and is converted
into ammonia and carbon dioxide.
CH*NO + HO = CO + 2NH3
This conversion of urea into carbonate of ammonia takes
place spontaneously in stale urine, under the influence of a
peculiar ferment (Van Tieghem).
Action of Heat on Urea.-Cyanuric Acid.-Urea fuses
at 120°. When it is rapidly heated to a higher temperature,
it disengages ammonia and leaves a white residue, which is
cyanuric acid. This body is tri-cyanic acid:
V
(CO)=NH
CON3H3
(CO)=NH
(CO)=NH
I
It results from the combination of three molecules of cyanic
acid, which are condensed into one, and held together by the
nitrogen which each contains. This is indicated by the lines
of union in the formula. Indeed, the three atoms of nitrogen
are arranged in a sort of ring, so that each of them has an
atomicity saturated by its neighbor.
N
N-N
Cyanuric acid is but slightly soluble in cold water. It sepa-
rates from its boiling aqueous solution in small, colorless crys-
tals, containing two molecules of water of crystallization.
By dry distillation, it is converted into cyanic acid.
Compounds of Urea with Acids. If nitric acid be added
to a concentrated solution of urea, the liquor assumes the form
of a white, crystalline, laminated mass, composed of crystals
of urea nitrate, CH*N2O.HNO³.
COMPOUND UREAS.
443
These crystals are soluble in water and alcohol. They
strongly redden litmus solution. They decompose at 140°,
disengaging a large quantity of gas.
The hydrochloride of urea, CH*N2O.HCl, and the oxalate,
(CH*N2O)³C2H2O+, are known. The latter salt precipitates in
small, colorless, granular crystals when a concentrated solution.
of oxalic acid is added to a concentrated solution of urea.
Compounds of Urea with Oxides and with Salts.-There
are several compounds of urea with mercuric oxide. They
are formed either by the direct action of mercuric oxide upon
urea, which dissolves that oxide, or by the reaction of mercuric
chloride or nitrate upon urea, which is precipitated by both of
these salts. A solution of urea converts recently-precipitated
silver oxide into a gray powder, which is a compound of urea
and oxide of silver. Among the compounds of urea with the
various salts, that which it forms with sodium chloride is the
most important. It crystallizes in colorless, oblique rhombic
prisms, containing CH NO.NaCl + H2O.
COMPOUND UREAS.
The compounds which are derived from urea by the substi-
tution of various alcoholic radicals for hydrogen are called
compound ureas. They are obtained either by the action of
cyanic acid upon the compound ammonias, or by treating the
cyanic ethers with ammonia or with the compound ammonias
(Ad. Wurtz).
CONH + N
NH(CH)
C2H5
H2
CO
NH2
Cyanic acid.
Ethylamine.
Ethylurea.
CON(CH) + NH3
CO<
.NH(CH)
NH2
Ethyl cyanato.
Ethylurea.
The following is the nomenclature and composition of some
of the principal compound ureas:
CH+N20 urea.
CI13(CH3) N2O methylurea.
CH3(C2H5) N20 ethylurea.
CH2(C2H5)2N20 diethylurea.
CH(C2H5)3N20 triethylurea.
CH3(C5H11) N20 amylurea.
CH3(C6115) N20 phenylurea.
CII²(C6H³)²N2O diphenylurea.
444
ELEMENTS OF MODERN CHEMISTRY.
POTASSIUM SULPHOCYANATE.
KCSN
This salt, which is sometimes called potassium sulphocyanide,
corresponds to the cyanate, in which the oxygen is replaced by
sulphur.
It is prepared by heating a mixture of two parts of potas-
sium ferrocyanide and one part of sublimed sulphur to redness
in a crucible or luted matrass. After cooling, the mass is
dissolved in water, the solution filtered, and potassium carbon-
ate added to the liquor as long as a precipitate of ferrous car-
bonate is formed. The solution is again filtered, evaporated to
dryness, the residue exhausted with alcohol, and the alcoholic
solution allowed to evaporate spontaneously.
Potassium sulphocyanate crystallizes in long striated prisms
resembling potassium nitrate, or in needles terminated by four-
faced points. It is deliquescent and very soluble in water and
alcohol.
Solution of potassium sulphocyanate produces an intense
blood-red color with the ferric salts, due to the formation of
ferric sulphocyanate.
Ammonium Sulphocyanate, NH+CSN.-This body corre-
sponds to ammonium cyanate. It occurs in the water from the
purification of coal-gas. When heated to 170°, it is converted
NH2
into sulpho-urea, CS<NH², fusible at 140° (Reynolds).
The sulphocyanates present an isomerism exactly like that
which has been mentioned for the cyanates.
MONATOMIC ALCOHOLS AND THEIR
DERIVATIVES.
These compounds form part of the great class of alcohols.
They are neutral hydrates, derived from hydrocarbons by the
substitution of the radical hydroxyl OH for an atom of hydro-
gen. Among these bodies, the more important are those which
belong to the same series, as ordinary alcohol, or ethyl hydrate,
which has been indicated on page 417. Wood-spirit, or methyl
hydrate, is the simplest term of the series. While studying its
combinations, in 1835, Dumas and Peligot were the first to call
attention to the function "alcohol."
METHANE.
445
METHYL COMPOUNDS.
In these compounds, we admit the existence of a radical,
CH³, to which the name methyl is given. Wood-spirit is its
hydrate; marsh gas, or methane, its hydride. To this hydride
correspond a chloride, a bromide, and an iodide. Chloroform
is dichloro-methylchloride, or trichloromethane. Around methyl
hydrate are grouped the salts of methyl or methylic ethers, re-
sulting from the action of the acids upon that body, and which
are to methyl hydrate as the potassium salts are to potassium hy-
drate. They are the compound methyl ethers. The following
formulæ indicate the relations which exist between these bodies:
CH³H
Methane, or methyl hydride.
CH³CI
Methyl chloride.
CHC13
CH3
0
H
Methyl hydrate.
CH³
0
CH3
Methyl oxide.
C'H O
0
ん
​CH3
Methyl acetate.
Chloroform.
These compounds will be but briefly described.
METHANE.
(MARSH GAS.)
CH+
The inflammable gas which is disengaged from the mud of
marshes is impure methane. The same gas is frequently
evolved in the galleries of coal mines, and constitutes the
fire-damp of miners. It is produced artificially by the action
of an excess of alkali upon acetic acid (Persoz, Dumas).
Preparation. Methane is most conveniently prepared in
the pure state by strongly heating in a glass flask or retort a
mixture of 1 part of sodium acetate, 1 part of potassium hy-
drate, and 1 parts of lime; the lime is added to prevent the
action of the potassium hydrate upon the glass. The gas may
be collected over water.
NaC²H³O² + NaOH
Sodium acetate.
CH+ Na2CO3
Methane.
Properties.-Methane is a colorless, odorless gas. Its den-
38
446
ELEMENTS OF MODERN CHEMISTRY.
sity is 0.559; it is but slightly soluble in water, somewhat more
so in alcohol. It burns in the air with a yellow flame less lumi-
nous than that of ethylene, or clefiant gas.
A mixture of me-
thane and oxygen explodes violently on the application of flame
or the passage of an electric spark.
If two volumes of methane and four volumes of oxygen be
introduced into an eudiometer and the spark be passed, a bright
flash is visible. After the combustion, the mercury rises in the
tube, and it is found that the volume of gas is reduced to one-
third of the primitive volume (to 2 volumes); if a solution of
potassium hydrate be introduced, the whole of the remaining
gas will be absorbed. 2 volumes of methane produce in burning
2 volumes of carbon dioxide, and require 4 volumes of oxygen.
This experiment permits the determination of the composition
of methane.
2 volumes of carbon dioxide contain 2 volumes of oxygen
combined with 1 volume (1 atom) of carbon; consequently two
volumes of marsh gas contain one atom of carbon.
The other two volumes of oxygen consumed have combined
with four volumes of hydrogen, which are likewise contained in
two volumes of methane.
Consequently two volumes of methane contain 1 atom of
carbon and 4 atoms of hydrogen.
A mixture of chlorine and methane explodes when exposed to
direct sunlight. In diffused daylight, the action is less violent,
especially if an inert gas, such as carbon dioxide, be added.
In this case, methyl chloride is formed, and in presence of an
excess of chlorine, chloroform, and finally carbon tetrachloride.
CH¹ + Cl² HC CH³Cl methyl chloride.
3HCl + CHCl3 chloroform.
4HCICCI¹ carbon tetrachloride.
CH¹ + 3C1²
CH¹ + 4C12
It is seen that in these reactions the chlorine is substituted
for hydrogen, atom for atom.
Inversely, when chloroform or carbon tetrachloride is sub-
mitted to the action of nascent hydrogen, an inverse substitu-
tion may be effected, and these chlorine compounds may be
converted into methane. This may be accomplished by putting
them in contact with sodium amalgam and water. The latter
is decomposed by the sodium, and constitutes a source of hy-
drogen (Melsens).
CHCP³ + 3H2
3HCI + CH¹
METHYL HYDRATE-METHYL OXIDE.
447
METHYL HYDRATE, OR METHYL ALCOHOL.
(WOOD-SPIRIT.)
CH¹O CH3-OH
The products of the dry distillation of wood contain about
one per cent. of a spirituous liquid, which was discovered in
1812 by Taylor, and named wood-spirit. It is separated by
several distillations and rectifications over lime; for, being more
volatile than the other products, it passes over first.
When pure, it is a mobile, colorless liquid, having an alco-
holic odor. It boils at 66.5°. Its density at 0° is 0.8142
(Dumas and Peligot).
It is inflammable and burns with an almost colorless flame.
It is miscible with water, alcohol, and ether in all proportions.
It dissolves caustic baryta and forms with it a definite combi-
nation. It forms a crystalline compound with calcium chloride
containing CaCl2 + 4CH¹O.
Potassium and sodium react energetically upon methyl hy-
drate; the metal dissolves with disengagement of hydrogen and
formation of potassium or sodium methylate.
CH3-OH
Methyl hydrate.
CH³-OK
Potassium methylate.
If methyl alcohol be placed under a bell-jar containing also
some watch-glasses filled with platinum black, so that the vapor
of the wood-spirit mixed with air may come in contact with
the finely-divided metal, it is found that the liquid soon becomes
strongly acid. By the slow oxidation of the wood-spirit under
these conditions, formic acid is produced (Dumas and Peligot).
CHO-OH + H3O
CH³-OH + 0²
Methyl hydrate.
Formic acid.
METHYL OXIDE.
(CH3)20
When methyl alcohol is heated with twice its weight of
concentrated sulphuric acid, a colorless gas is disengaged, which
is methyl oxide.
(CH3)2O + H2O
2CH³.OH
Methyl hydrate.
Methyl oxide.
448
ELEMENTS OF MODERN CHEMISTRY.
This gas is formed by the dehydration of methyl alcohol
and the linking together of two methyl groups by an atom of
oxygen. It is methylic ether. It holds the same relation to
methyl hydrate that ordinary ether does to ethyl hydrate.
It is colorless, very soluble in alcohol and ether, and quite
soluble in water. It liquefies at a very low temperature.
(—36°).
CHLORIDE, BROMIDE, AND IODIDE OF METHYL.
These compounds may be regarded as marsh gas in which
one atom of hydrogen is replaced by an atom of chlorine, bro-
mine, or iodine.
They are formed by the action of hydrochloric, hydrobromic,
and hydriodic acids upon methyl alcohol.
CH³.OH + HCl CH³CI + H2O
They may be considered as derived from the hydracids by
the substitution of the group methyl for the atom of hydrogen.
HCI
Hydrochloric acid.
(CH³)CI
Methyl chloride.
Methyl chloride is a colorless gas, having an agreeable odor.
When exposed to intense cold, it condenses to a liquid which
boils at -22°. When heated for a considerable time with
a concentrated solution of potassium hydrate, it is converted
into methyl alcohol.
Methyl bromide, CH'Br, is a colorless liquid, boiling at
13°.
Methyl iodide, CHI, boils at 43°; its density at 0° is 2.1992.
It is made by gradually adding iodine to a mixture of methyl
alcohol and amorphous phosphorus, and distilling. The dis-
tilled liquid is mixed with water, which precipitates the iodide;
the dense liquid is separated, dried with calcium chloride, and
distilled.
CHLOROFORM.
CHC13
This important substance was discovered in 1831 by Soubei-
ran and Liebig. It is made by distilling either alcohol or wood-
spirit with a mixture of chloride of lime and calcium hydrate.
The distilled liquid separates in two layers, of which the lower
METHYL CYANIDE.
449
is impure chloroform. It is separated, washed first with water
and then with a solution of potassium carbonate, and rectified
over calcium chloride.
Chloroform is a colorless, very mobile liquid, having an
agreeable, ethereal odor. Its density is 1.48, and it boils at
60.8°. It does not take fire on contact with flame.
It is but slightly soluble in water, but dissolves readily in
alcohol and ether. It dissolves sulphur, phosphorus, fats,
resins, a great number of the alkaloids, and in general, organic
matters rich in carbon.
By the prolonged action of chlorine, it is converted into
carbon tetrachloride, CCI, a colorless liquid boiling at 77°.
A boiling alcoholic solution of potassium hydrate converts it
into formate and chloride.
CHC¹³ + 4KOH = 2H2O + 3KCl + KCHO²
Chloroform.
Potassium formate.
When chloroform is boiled with an alcoholic solution of
ethylate of sodium, sodium chloride is formed, together with
an ethereal compound, CH(OC'H)3, in which 3 oxethyl groups,
OC'H³, replace the 3 chlorine atoms of chloroform (Kay).
5
CHCP³+3NaO.C'H 3NaCl + CH(OCH)3³
Chloroform. Sodium ethylate.
Kay's ether.
Chloroform, heated to 180° with aqueous or alcoholic ammo-
nia, yields ammonium cyanide and sal-ammoniac. This re-
action takes place at 100°, in presence of potassium hydrate.
NH CN +3NH CI
CHCI³ + 5NH³
Chloroform acts in a remarkable manner upon the phenols
in presence of an alkali such as soda or potassa, forming aro-
matic aldehydes. This reaction, discovered by Reimer, will be
described farther on (see Phenol).
Chloroform is much employed in surgery as an anæsthetic.
The inhalation of its vapor produces insensibility and loss of
muscular action.
METHYL CYANIDE.
C2H3N CH³Cy
This body may be obtained by distilling a mixture of potas-
sium methylsulphate and potassium cyanide, or by distilling
acetamide with phosphoric anhydride, which removes one mol-
ecule of water from the former body.
*
38*
450
ELEMENTS OF MODERN CHEMISTRY.
C2H3O.NH2
Acetamide.
H2O
C2H³N
Methyl cyanide, or
acetonitrile.
The product obtained in the latter operation is called ace-
tonitrile.
Methyl cyanide is a colorless liquid, having a disagreeable
odor; it boils at 77°. A boiling solution of potassium hydrate
decomposes it into ammonia and potassium acetate.
CH³-CN + 2H2O = CH³-CO.OH + NH³
Methyl cyanide.
Acetic acid.
Gautier has discovered an isomeride of methyl cyanide,
methyl carbylamine. This body is formed, together with
methyl cyanide, when a mixture of potassium methylsulphate
and potassium cyanide is distilled. Under the influence of alka-
lies, it decomposes into formic acid and methylamine.
KCHO² + CH2}
C"
CH3
}
} N +
KOH + H2O
Methyl carbylamine.
Potassium formate.
HN
Methylamine.
METHYL NITRATE.
CH³. NO3
This substance, which represents nitric acid in which the
basic hydrogen is replaced by methyl, is an example of a com-
pound methyl ether.
It is prepared by introducing into a retort 50 grammes of
powdered potassium nitrate, and adding a mixture of 100
grammes of sulphuric acid and 50 grammes of wood-spirit.
The reaction begins in the cold, but must be finished by dis-
tilling on a water-bath. The liquid condensed in the receiver
is washed with water, and rectified several times over a mix-
ture of massicot and calcium chloride.
It is a colorless, neutral liquid; density, 1.182; boiling-point,
66°. Its vapor explodes violently when heated above 150°.
Methyl nitrate dissolves in ammonia, producing ammonium
nitrate and methylamine.
CH³.NO³+2NH NH.NO + CH³(NH2)
METHYL NITRITE AND NITROMETHANE.
These two compounds present a remarkable instance of
isomerism in very simple combinations.
The first, CH O.NO, which represents nitrous acid, HNO3,
METHYL NITRITE AND NITROMETHANE.
451
in which the hydrogen is replaced by methyl, is obtained when
methyl alcohol is heated with nitric acid in presence of copper.
It is a liquid boiling at about -12°.
The second, called also nitrocarbol, represents methane, in
which an atom of hydrogen is replaced by the group (NO²)'.
CH⭑
Methane.
CH³ (NO)
Nitromethane.
It is obtained by the action of potassium nitrite upon potas-
sium monochloracetate (Kolbe).
CHI2C1.CO²K + KNO2 + H2O
Potassium mono-
chloracetate.
Potassium
nitrite.
KC + CH3(NO2) + KHCO3
Nitromethane.
It is also produced by the action of silver nitrite on methyl
iodide (V. Meyer).
It
Nitromethane is a liquid boiling between 101 and 102°.
has an acid character, and one of its hydrogen atoms may be
replaced by sodium.
Nitromethane is clearly distinguished from methyl nitrite by
the following property: nascent hydrogen transforms nitrome-
thane into methylamine, a reaction which does not take place
with its isomeride.
CH³(NO2) + 3H2
Nitromethane.
CH³.NH² + 2H2O
Methylamine.
METHYLNITROLIC ACID.
NO2
CH²N²O³ = CH«N.OH
This remarkable combination has been obtained by V. Meyer
by the action of nitrous acid upon nitromethane.
CH³(NO²) + NO.OH
CH
NO2
"N-OH + H2O
It is seen that in this compound two atoms of hydrogen of
the methyl group CH³, are removed by an atom of oxygen of
the nitrous acid, and replaced by the residue (N.OH).
Methylnitrolic acid is prepared by dissolving 5 grammes of
nitromethane in water, and adding first a dilute solution of
potassium nitrite cooled to 0°, then dilute sulphuric acid also
cooled to 0°, and finally dilute solution of potassium hydrate
as long as the red color persists. At this moment, sulphuric
acid is again added until the liquid is decolorized; the solution
is then saturated with calcium carbonate, and agitated with
ether, which dissolves the methylnitrolic acid.
452
ELEMENTS OF MODERN CHEMISTRY.
After the evaporation of the ether, the acid remains as large,
transparent, colorless prisms, fusible at 54°, but decomposing
at the same time into formic acid and nitrogen. Dilute sul-
phuric acid decomposes methylnitrolic acid into formic acid and
nitrogen monoxide.
CH2N203
CH2O2
+
Formic acid.
N20
Nitrogen monoxide.
The crystals decompose spontaneously in a few days.
FULMINATES OF MERCURY AND SILVER.
Among the important compounds related to the more simple
organic combinations are those explosive salts known as fulmi-
nates of mercury and silver.
They are obtained by dissolving mercury or silver in nitric
acid and adding alcohol to the still hot solution. In a few
minutes a brisk effervescence takes place, and fulminate of
mercury or of silver is deposited as a white, crystalline precip-
itate. When dry, these bodies explode violently by either heat
or percussion. Fulminate of mercury is the basis of percus-
sion-caps.
The composition of these salts is interesting; fulminate of
mercury contains a monatomic group, (NO2), a cyanogen group,
(CN), and an atom of mercury, all three being united to an
atom of carbon, of which the four atomicitics are thus perfectly
satisfied.
Fulminate of silver has an analogous composition, but con-
tains two atoms of silver.
The fulminates may thus be grouped with organic compounds
containing one atom of carbon, especially with the cyanide of
methyl (Kekulé). The following are some of these com-
pounds:
CHH HH
CHHH Cy
C(NO2) H H H
C(NO2) H H Na
C(NO2) H H Cl
C(NO2) C1 CI CI
C(NO2) (NO2) (NO2)H
C(NO2)4
C(NO2) Ag Ag Cy
C(NO2) Hg"
methane.
methyl cyanide.
nitromethane.
sodium-nitromethane.
chloro-nitromethane.
trichloro-nitromethane (chloropicrin).
nitroform.
tetranitromethane.
fulminate of silver.
Cy
fulminate of mercury.
CACODYL.
453
CACODYL, OR DIMETHYLARSINE.
As²(CH3)4
This interesting compound has long been known in an im-
pure state. In 1760, Cadet, demonstrator of chemistry at the
Jardin-du-Roi, distilled a mixture of potassium acetate and
white arsenic (arsenious oxide). He collected in the receiver
an oily liquid, having an extremely offensive odor, and pro-
ducing dense white fumes in the air. Hence the name fuming
liquor of Cadet.
Bunsen's investigation into the chemistry of this body and
its combinations has become classic. According to his re-
searches, the fuming liquor of Cadet is a mixture of two bodies,
one of which, containing only carbon, hydrogen, and arsenic,
plays the part of a radical: it is cacodyl; the other body is the
oxide of this radical.
To obtain cacodyl in the pure state, the crude product is
treated with hydrochloric acid, which converts the oxide of
cacodyl into chloride.
As²(CH)0 + 2HCl
Dimethylarsine oxide.
2As(CH)2Cl + H2O
Dimethylarsine chloride.
This chloride, separated by distillation, and treated with zinc
at 100° in sealed tubes, furnishes free cacodyl.
The latter is a dense liquid boiling at 170°, and having a
penetrating arsenical odor. It is very poisonous. It produces
dense white fumes in the air, even taking fire spontaneously.
Its vapor density is 7.101.
According to this vapor density, free cacodyl should be rep-
resented by the formula As²(CH3) = (CH3) As-As(CH³)².
Arsenic being either triatomic or pentatomic it is seen that
cacodyl is not saturated; hence it can directly fix chlorine,
oxygen, etc., yielding two series of compounds. Thus, one
molecule of cacodyl, As Me¹, can fix 1 or 3 molecules of chlo-
rine, forming the two chlorides:
As² Met + C13 2AsMc2Cl
As²Met + 3C12 2AsMe2C13
To the two chlorides correspond the bromides, iodides, oxides,
sulphates, etc.
The oxides are
Cacodyl oxide [As(CH3)2]20
Cacodylic acid As(CH3)20.0H
3
454
ELEMENTS OF MODERN CHEMISTRY.
Independently of the cacodyl compounds, other combinations
of arsenic and methyl are known, the methylarsines and the
compounds of methylarsonium.
These bodies form two series, which were discovered and
studied by Baeyer, and which belong to the type AsX³ and
AsX³. The compounds of the first kind are not saturated, and
can combine with Cl2, or the equivalent of Cl², passing into the
state of the saturated compounds of the series AsX³.
Series AsX3
As(CH3)3
Trimethylarsine.
As(CH3)2Cl
Dimethylarsine monochloride.
As(CH³) C12
Monomethylarsine dichloride.
AsC13
Arsenic trichloride.
Series AsX5
As(CH³) 4Cl
Tetramethylarsonium chloride.
As(CH3)3C12
Trimethylarsine dichloride.
As(CH3)2C13
Dimethylarsine trichloride.
As(CH³) Cl
Monomethylarsine tetrachloride.
[AsC15]
It is worthy of remark that the trichloride of arsenic is
incapable of fixing Cl, and passing into the state of penta-
chloride.
These compounds need not be described. It may only be
mentioned that trimethylarsine, As(CH3)3, is formed, together
with cacodyl, by the action of methyl iodide on sodium arsenide.
It is a liquid boiling below 100°.
ETHYL COMBINATIONS.
The monatomic residue (C2H5)'
C'² He
H, which is the
radical of ordinary alcohol, is called ethyl. Numerous com-
pounds are known into which the radical enters.
When combined with hydrogen, it forms a gas, C2H6, which
is ethyl hydride or ethane. The chloride, bromide, iodide, and
cyanide of ethyl were formerly designated as simple ethers.
C2H5C1
C2H5 Br
C2H5I
C3H5.CN
ethyl chloride.
ethyl bromide.
ethyl iodide.
ethyl cyanide.
Ordinary alcohol is the hydrate, ether is the oxide of ethyl.
C2H5-OH
ethyl hydrate (alcohol).
C2H5-0-C2H5
(C2H5)2O ethyl oxide (ether).
ETHYL HYDRATE.
455
The neutral compound ethers are derived from the corre-
sponding acids by the substitution of the radical C2H5 for their
basic hydrogen.
C2H30-OH
Acetic acid.
C202
{
он
он
Oxalic acid.
он
PO OH
OH
Phosphoric acid.
C2H30-0C2H5
Ethyl acetate.
O.C2H5
C202 {0.C2H5
Ethyl oxalate.
0.C2H5
PO O.C2H5
{
O.C2H5
Phosphoric ether (triethyl phosphate).
Ethyl exists in the most diverse combinations.
It can re-
place the hydrogen of ammonia, forming ethylated bases. It
can unite with the metalloids and metals.
Free Ethyl, or Butane, CH¹.-When it is sought to obtain
free ethyl by heating ethyl iodide to 150° with zinc in sealed
tubes, the radical combines with itself, its molecule being doubled
(Frankland).
2C2H³I + Zn = ZnI² + (C²H³)²
A gas is thus formed which liquefies at +1°. It was
formerly named free ethyl, but is the hydride of butyl, or
butane. Indeed, it is incapable of regenerating ethyl compounds
containing the simple radical (C2H5). When treated with bro-
mine, it yields hydrobromic acid and a bromide C'H Br", which,
according to Carius, is identical with butylene bromide.
Ethyl Hydride, or Ethane, CH=CH-CH³.-Frank-
land obtained this gas by treating zinc-ethyl with water.
2C²H® + Zn(OH)²
Zinc hydrate.
Zn(CH 2 + 2H2O
Zinc ethyl.
Ethane.
It is a colorless gas, burning with a slightly blue, luminous
flame. When treated with chlorine, it yields ethyl chloride
and hydrochloric acid.
ETHYL HYDRATE, OR ALCOHOL.
C2H6O CH³-CH2.OH
Alcohol is the product of the fermentation of solutions which
contain glucose, or a substance capable of transformation into
glucose.
It may be formed synthetically in various manners:
1. By passing ethylene gas into sulphuric acid (Hennel and
456
ELEMENTS OF MODERN CHEMISTRY.
Faraday) and boiling the ethylsulphuric acid so formed (Ber-
thelot).
C2H5
H
}
Ethylene.
CH5
C2H⭑
+ H2SO4
SO¹
H
Ethylsulphuric acid.
SO¹ + H2O =
C2H5OH + H2SO¹
Alcohol.
Ethylsulphuric acid.
2. By heating ethylene gas with hydriodic acid and decom-
posing the ethyl iodide so formed with potassium hydrate (Ber-
thelot).
C²H✩ + HI
C2H5I
C²H³I + KOH = C²H³.OH + KI
3. By bringing aldehyde in contact with sodium amalgam in
presence of water. The nascent hydrogen formed in this case
fixes upon the aldehyde, converting it into alcohol (A. Wurtz).
C²H¹O + H²
Aldehyde.
C2H6O
Alcohol.
Preparation and Purification of Alcohol.-Alcohol is
manufactured by distilling fermented liquors, such as wine,
fermented juice of beet-roots, and the product obtained from
the fermentation of malt, which is saccharified barley, corn, or
other grain. The apparatus now used for this operation has
reached such a degree of perfection that alcohol of 95 per cent.
may be obtained immediately by one distillation.
Absolutely pure alcohol is obtained by rectifying the alcohol
of commerce over substances avid of water, such as anhydrous
potassium carbonate, quick-lime, or caustic baryta. The last
portions of water are removed, and absolute alcohol obtained
by redistilling the rectified alcohol with caustic baryta. Or
some sodium may be dissolved in the alcohol, which may then
be rectified on a water-bath.
Properties. Alcohol is a colorless, mobile liquid, having an
agreeable, spirituous odor. Density at 0°, 0.8095. Boiling-
point, 78.4° at the normal pressure.
Alcohol mixes with water and ether in all proportions. Its
mixture with water takes place with elevation of temperature
and contraction of volume. The maximum contraction takes
place when the two bodies are mixed in the proportion of one
molecule of alcohol (53.94 parts) to three molecules of water
(49.84 parts).
ETHYL HYDRATE.
457
It dis-
Alcohol absorbs moisture when exposed to the air.
solves many gases, liquids, and solids. Tinctures are solutions.
of various medicinal substances in alcohol.
Among the simple bodies which are soluble in alcohol may
be mentioned iodine. Potassium and sodium hydrates dissolve
in it readily, and it is the same with most of the mineral acids.
Many of the chlorides are soluble in alcohol; such are those of
calcium, strontium, zinc, and cadmium, ferric, cupric, mercuric,
and auric chlorides.
Alcohol dissolves the natural alkaloids, the essential oils,
resins, and fatty bodics, the latter, however, less readily than
ether.
Decompositions. When vapor of alcohol is passed through
a red-hot porcelain tube, it is decomposed into water, carbon
monoxide, hydrogen, methane, and ethylene. Besides this,
carbon is deposited in the porcelain tube, and a small quantity
of naphthaline is produced (Th. de Saussure), as well as
benzol and phenol (Berthelot). The principal products of
the decomposition of alcohol at a dull-red heat are methane,
hydrogen, and carbon monoxide.
+H
CHO = CO + CH* + H
On the application of a burning body, alcohol takes fire
and burns with a slightly luminous, bluish flame. On contact
with platinum black, alcohol vapor mixed with air undergoes a
slow combustion, which produces successively aldehyde and
acetic acid.
C²Hº0 + 0 = C²H¹O + H2O
Alcohol.
C²H¹OO
Aldehyde.
Aldehyde.
C²H¹O²
Acetic Acid.
Acetic ether and a small quantity of a volatile, neutral body,
called acetal, are at the same time formed as accessory products
(Stas).
The lamp without flame of Döbereiner depends upon the
slow combustion of alcohol. The wick of an ordinary spirit-
lamp is surmounted by a spiral of platinum wire, so that when
the lamp is lighted the spiral is heated to incandescence. If
then the flame be extinguished, by covering it for an instant
with a test-tube, the alcohol vapor continues to rise with the
air around the still hot spiral, and undergoes a slow combustion.
But the latter develops heat, and the spiral rapidly becomes
U
39
458
ELEMENTS OF MODERN CHEMISTRY.
heated to incandescence, and if the current of air be regulated
by a small glass chimney, the experiment may continue as long
as the wick emits vapor of alcohol in sufficient quantity.
Bodies rich in oxygen oxidize alcohol at ordinary tempera-
tures; such are chloric and chromic acids. If a little alcohol
be poured upon some chromic acid placed upon a brick, the
liquid is immediately inflamed and the chromic acid reduced
to chromium oxide.
Chlorine attacks alcohol with great energy, the final product
of the reaction being a body which has received the name
chloral (Liebig, Dumas).
If a small piece of potassium or sodium be thrown into pure
alcohol, the metal soon melts, and then dissolves with disen-
gagement of hydrogen. The product of the reaction is a crys-
talline, solid matter which is ethylate of potassium or sodium,
that is, a body derived from alcohol by the substitution of an
atom of an alkaline metal for an atom of hydrogen.
C2H5
H
Alcohol.
0
C2H5
K
Potassium ethylate.
C2H5
0
Na
Sodium ethylate.
Uses of Alcohol.-Alcohol is used as a combustible in spirit-
lamps. In the arts, it is employed in the manufacture of ether,
chloroform, eau de cologne, and many other products. It is
largely used in the laboratory, and in pharmacy, as a solvent;
it serves for the preservation of anatomical specimens. In
France and England, alcohol employed for certain industrial
uses is exempted from part of the tax, when it has previously
been mixed with about one-tenth of wood-spirit and a few
per cent. of mineral oils and resin. Such a mixture is unfit
for the manufacture of brandy and liquors, but its usefulness
as a solvent is in many cases unimpaired.
Alcohol exists in fermented liquors, such as wine, cider, and
beer. It is contained in much larger quantities in brandics,
whiskeys, and spirits. These are products of the distillation of
various alcoholic liquids. They are more or less rich in alco-
hol. Brandy is prepared by the distillation of wine, cider, or
the products of fermentation of cherry-juice (cherry-brandy),
sugar-cane (rum), bect-root molasses (beet-brandy). Whiskey
is distilled from fermented starchy materials, such as corn, rye,
potatoes, etc., the starch being first saccharified. The richness
of these materials in alcohol is indicated by the degrees of an
ETHYL OXIDE.
459
alcoholometer. The following table gives the strength of some
of these liquors.
PERCENTAGE OF
ALCOHOL.
Weak brandy
Proof spirits
Strong brandy
Ordinary alcohol
CARTIER'S AREOMETER.
BY VOLUME.
16°
37.9
19°
50.1
22°
59.2
33°
85.1
95.
41.2°
100.
Rectified alcohol (strongest commercial) 40°
Absolute alcohol
ETHYL OXIDE, OR ETHER.
(C2H5) 20
CH3-CH2-O-CH2-CH3
If ethyl iodide be added to an alcoholic solution of ethylate
of sodium and a gentle heat be applied, a deposit of sodium
iodide is formed and vapors are disengaged which may be con-
densed in a cooled receiver into an ethereal liquid.
oxide of ethyl.
C2H5
C2H5I +
Ethyl iodide.
Na
Sodium ethylate.
NaI +
C2H5
C2H5
Ethyl oxide.
It is
If, in the preceding experiment, the ethyl iodide be replaced
by methyl iodide, an extremely volatile liquid will be formed,
which is the double oxide of methyl and ethyl.
CH³I +
Methyl iodide.
C2115
Na
C2H5
0
NaI +
CH3
Oxide of methyl and ethyl.
These classic experiments, due to Williamson, show that
the oxide of ethyl contains two ethyl groups. It may be
regarded as alcohol in which the hydrogen atom of the group
hydroxyl is replaced by ethyl.
H-O-H
Water.
C2H5-O-H
Alcohol.
C2H5-0-C2H5
Ethyl oxide.
Preparation.-Ether is prepared in the arts by the action.
of sulphuric acid on alcohol. A mixture of 9 parts of con-
centrated sulphuric acid and 5 parts of alcohol of 90 per cent.
is heated in a flask, A (Fig. 122), and a small, continuous
stream of alcohol is allowed to flow into this mixture through
the funnel-tube a. The temperature of the liquid, indicated by
the thermometer t, should not exceed 140 or 145°. The vapor
disengaged is condensed in a Liebig's condenser, B, through
which a stream of cold water flows continually. Under these
460
ELEMENTS OF MODERN CHEMISTRY.
conditions, a mixture of ether and water collects in the re-
ceiver D, together with a little alcohol, and towards the close
of the operation, a small quantity of sulphurous acid gas is
disengaged. The product is purified by washing with milk of
lime, and then with pure water, after which it is rectified over
calcium chloride on a water-bath. Fig. 122 represents the
apparatus used for public demonstration; in the arts, the opera-
tion is conducted on a large scale in apparatus of an analogous
construction.

D
ملابنات
ALQUERA A KA KA
B
A
FIG. 122.
Theory of Etherification. The transformation of alcohol
into ether is a true dehydration, brought about by the sul
phuric acid.
2(C²H³.OH) = (C²H³)²O + H2O
Williamson clearly proved that it is effected in two distinct
phases; in the first, ethylsulphuric acid and water are formed.
C2H6.
H
+
H
H
C2H5
SOL
SO4 + H2O
Alcohol.
Sulphuric acid.
H
Ethylsulphuric acid.
ETHYL OXIDE.
461
In the second, another molecule of alcohol reacts with the
ethylsulphuric acid; ether is formed and sulphuric acid is
regenerated.
C2H5
SO4 +
H
Ethylsulphuric acid.
C2H5
C2H5
H
0 +
S04
H
C2H5
H
Alcohol.
Ether. Sulphuric acid.
Hence the ether and water collected in the receiver are pro-
ducts of two distinct phases of the reaction. Ethylsulphuric
acid is continually formed and as continually decomposed,
regenerating sulphuric acid ready to act upon new por-
tions of alcohol. However, although the operation is con-
tinuous, it cannot go on indefinitely, for the mixture blackens
after a time and becomes unfit to etherify new quantities of
alcohol.
Properties of Ether.-Ether is a colorless, very mobile
liquid; its taste is at first burning, then cooling; its odor is suave
and agreeable, and is called ethereal. Density at 0°, 0.7366.
Boiling-point under the normal pressure, 34.5°.
It is but slightly miscible with water, on the surface of which
it forms a separate layer. 9 parts of water dissolve 1 part of
ether; 36 parts of ether dissolve 1 part of water. Ether dis-
solves in all proportions in alcohol and in methyl alcohol.
It slightly dissolves sulphur and phosphorus, and notable
quantities of bromine, iodine, ferric, mercuric, and auric chlo-
rides, and many organic bodies, such as the oils, fats, resins,
alkaloids, etc.
It is very inflammable and burns with a quite luminous
flame. Its vapor explodes violently when mixed with air or
oxygen and ignited.
If a heated spiral of platinum wire be suspended in a glass
jar containing a little ether, in such a manner that the lower
extremity of the wire is but a little distance from the surface
of the liquid, the wire will soon become brightly incandescent
and will ignite the ether.
This effect is due to the ether vapor, which, coming in con-
tact with the platinum, and being mixed with air, undergoes a
slow combustion. Heat is thus developed, and the wire be-
comes incandescent.
Chlorine acts on ether with extreme energy. If the action
be moderated, various products of substitution are obtained,
among which the following have been well studied:
39*
462
ELEMENTS OF MODERN CHEMISTRY.
C2H4C1
Monochlorether
0
C2H5
liquid boiling at 98-99º.
C2H3C12
Dichlorether
0
C2H5
liquid boiling at 140-147°.
C2H3C12
Tetrachlorether
0
C2H3C12
liquid, density 1.5.
C2C15
Perchlorether
0
C2C15
colorless crystals, fusible at 69°.
The last is a solid body, crystallizing in octahedra. By the
action of heat it is decomposed into carbon sesquichloride and
perchloraldehyde (Malaguti).
C2C15.
C2C15
Perchlorether.
C2C16
+
C2C140
Carbon sesquichloride. Perchloraldehyde.
When two parts of bromine are added to one part of ether,
and the mixture is cooled, a garnet-colored liquid separates
and soon crystallizes. It is a compound of bromine and ether,
(C2H5)2O.Br², which crystallizes in thin, red plates, fusible at
22°; it is easily decomposed (Schützenberger).
SULPHYDRATE AND SULPHIDE OF ETHYL.
Two bodies are known which are intimately related, as re-
gards their constitutions, with alcohol and ether. They are
the sulphydrate and the sulphide of ethyl. The first, formerly
known as mercaptan, represents alcohol containing an atom of
sulphur instead of an atom of oxygen; the second represents
ether in which the oxygen atom is replaced by sulphur.
C2H5.OH
Ethyl hydrate.
C2H5.SH
Ethyl sulphydrate.
(C2H5) 20
Ethyl oxide.
(C2H5)2S
Ethyl sulphide.
Ethyl sulphydrate is obtained by distilling a concentrated
aqueous solution of potassium sulphydrate with a solution of
potassium ethylsulphate.
It may also be prepared by passing vapor of ethyl chloride
into an alcoholic solution of potassium sulphydrate. The liquid
is distilled as soon as it is saturated with ethyl chloride, and
water is added to the distillate. Ethyl sulphydrate separates.
KCl + C²H³.SH
Ethyl sulphydrate.
KSH
Potassium sulphydrate.
+ C2H5Cl
Ethyl chloride.
ETHYL CHLORIDE.
463
Ethyl sulphydrate is a transparent, colorless liquid, very mo-
bile, and having a fetid odor. Density at 21°, 0.835. Boil-
ing-point, 36.2° (Liebig).
It reacts energetically with mercuric oxide, forming water
and a white, crystalline body which represents ethyl sulphy-
drate in which the hydrogen is replaced by mercury. Hence
the name mercaptan (mercurium captans), given to the sulphy-
drate of ethyl by Zeise. This mercuric compound is insoluble
in water; it contains (C'H'S)'Hg".
Ethyl sulphide is obtained, like the sulphydrate, by double
decomposition. Vapor of ethyl chloride is passed into an alco-
holic solution of potassium monosulphide.
K2S +
Potassium sulphide.
2C2H5Cl
Ethyl chloride.
2KCl + (C2H5) S
Ethyl sulphide.
Ethyl sulphide is a colorless liquid, having a garlicky odor.
It boils at 75°. It is insoluble in water.
ETHYL CHLORIDE.
C2H5C1
This body is prepared by saturating alcohol with hydrochloric
acid gas and distilling on a water-bath. Ethyl chloride is dis-
engaged, and should be passed first through a wash-bottle and
then through a tube containing calcium chloride, after which it
may be condensed in a receiver placed in a freezing mixture.
Below 11° ethyl chloride is a mobile, colorless liquid, having
a penetrating and agreeable odor. It boils at 11°; it is inflam-
mable, and burns with a flame tinged with green.
If some solution of silver nitrate be agitated in a jar con-
taining vapor of ethyl chloride, no precipitate will be formed;
but if the agitation be continued after the vapor has been
ignited, an abundant precipitate of silver chloride will be
formed, owing to decomposition of the silver nitrate by the hy-
drochloric acid produced by combustion of the ethyl chloride.
Ethyl chloride produces a precipitate of silver chloride when
passed into an alcoholic solution of silver nitrate.
Chlorinated Derivatives of Ethyl Chloride. When ethyl
chloride is submitted to the action of chlorine, various com-
pounds are successively formed by the substitution of chlorine
for hydrogen, atom for atom. The following is the nomencla-
464
ELEMENTS OF MODERN CHEMIETRY.
ture and composition of these chlorinated compounds, which
were discovered by V. Regnault.
C2H5CI ethyl chloride.
C2H4C12 dichlorethane (ethylidine chloride)-boils at 57.5°.
C2H3C13 trichlorethane-boils at 75°.
C2H2C14 tetrachlorethane-boils at 127.5°.
C2HC15 pentachlorethane-boils at 158°.
C2C16 hexachlorethane (sesquichloride of carbon).
It will be noticed that the second of these compounds is
isomeric with ethylene chloride, or Dutch liquid, of which the
description will be found farther on. It may be obtained by
treating aldehyde with phosphorus pentachloride.
CH3-CHO + PC CH³-CHCI² + POCI³
Aldehyde.
Dichlorethane.
Phosphorus oxychloride.
This mode of formation indicates its constitution, which is
expressed by the formula
CH³
CHC12
To distinguish it from its isomeride ethylene chloride,
CH2Cl
CH²CI
it is named dichlorethane or ethylidene chloride.
In the sesquichloride of carbon, C2C16, the hydrogen atoms
are all replaced by chlorine. Carbon sesquichloride is a crys-
stalline solid, melting at 162°, and boiling at 182° (Faraday).
ETHYL IODIDE.
C2H5I
This important compound is prepared by the action of alco-
hol on iodine in presence of amorphous phosphorus. Phos-
phorus iodide is formed, and reacts upon the alcohol, yielding
ethyl iodide and an acid of phosphorus. The former distils
into the receiver, together with the alcohol which escapes the
reaction. Water is added, and the lower layer of liquid
separated, dried with calcium chloride, and rectified on a water-
bath.
Ethyl iodide is a colorless liquid, but becomes brown when
long kept, especially when exposed to light. Density at 0°,
1.9753. Boiling-point, 72.2°.
ETHYL CYANIDE.
465
It can exchange its iodine by double decomposition, as can
potassium iodide. If ethyl iodide be added to an alcoholic
solution of silver nitrate, a yellow precipitate of silver iodide
is at once formed, while ethyl nitrate remains in solution.
C²H³I+
AgNO³
+
AgI (C2H5) NO
(C²H³)NO³
+
Ethyl iodide.
Silver nitrate.
Ethyl nitrate.
ETHYL CYANIDE.
C3H5N CH3-CH2-CN
This compound is formed when ammonium propionate is
distilled with phosphoric anhydride.
(NH*)C3HO
C³H³N + 2H²0
Ammonium propionate. Ethyl cyanide.
From this mode of formation, ethyl cyanide is sometimes
called propionitrile. The same body exists in the product of
the distillation of a mixture of potassium cyanide and potassium
ethylsulphate.
KCN+
C2H5
K
SOL
Potassium
K
Potassium
Κ
K>Sot
$0$ +
C2H5.CN
Potassium
Ethyl cyanide.
cyanide. ethylsulphate.
sulphate.
But this product, which is liquid and has a variable boiling-
point, contains, independently of the true cyanide of ethyl, an
isomeride of that body, whose existence was foreseen by Meyer
and discovered by Gautier in the product of the action of
ethyl iodide on silver cyanide.
Ethyl cyanide is a colorless liquid having a penetrating and
pleasant odor. It boils at 96.7°
When it is boiled with potassium hydrate, potassium propio-
nate is formed and ammonia is disengaged (Dumas, Malaguti,
and Le Blanc).
C³H³N + KOH + H²0 KCHO + NH3
Ethyl cyanide.
Potassium propionate.
When ethyl cyanide is brought into contact with dilute sul-
phuric acid and zinc, it fixes 4 atoms of hydrogen and is
converted into propylamine (Mendius).
C³H³N + H*
Ethyl cyanide,
C3H9N
Propylamine.
Ethylcarbylamine.-This name was given by Gautier to the
isomeride of ethyl cyanide already mentioned. It is a color-
less liquid, having a very penetrating and intensely offensive
U*
466
ELEMENTS OF MODERN CHEMISTRY.
odor. It boils at 79°. With potassium hydrate it yields po-
tassium formate and ethylamine.
C2H5
C"
C2H5 N + KOH + H2O
H-N
+ KCH02
H
Ethylcarbylamine.
Ethylamine.
Potassium
formate.
ETHYL NITRITE, OR NITROUS ETHER.
C2H5.0-NO
This compound is obtained by the action of nitric acid on
alcohol. The reaction is very violent, and abundant red vapors
are evolved. After passing through a wash-bottle, they are
conducted into a well-cooled receiver, where the ethyl nitrite
condenses.
It is a yellowish, very volatile liquid, whose odor recalls that
of apples. It boils at 18°. It is but slightly soluble in
water. Hot water immediately decomposes it into alcohol and
nitrous acid, the latter being itself decomposed into nitric acid
and nitrogen dioxide.
NITRETHANE AND ITS DERIVATIVES.
C2H5-NO2
This isomeride of ethyl nitrite represents ethane, CH, in
which one atom of hydrogen is replaced by the group (NO2).
It is the superior homologue of nitromethane.
It is obtained, together with a certain quantity of ethyl
nitrite, when ethyl iodide is treated with silver nitrite.
C²H³I+ AgNO²
Ethyl iodide.
Silver nitrite.
C2H5(NO2) + AgI
Nitrethane.
It is a liquid having a peculiar, ethereal odor and boiling at
113-114°. Density at 13°, 1.0582 (V. Meyer).
With nascent hydrogen, it furnishes pure ethylamine.
C²H³(NO²) + 3H2 = C²H³(NH2) + 2H2O
All of the homologues of nitrethane thus yield the corre-
sponding amines. It is a general character of the nitro com-
pounds, and one which is not possessed by their isomerides,
the nitrous ethers. In constitution and properties, nitrethane
ETHYL NITRATE.
467
approaches nitrobenzol, as will be seen by the following com-
parison of their formula:
C²H³. H
Ethane.
C2H5(NO2)
Nitrethane.
C6H5.H
Benzol.
C6H5(NO2)
Nitrobenzol.
C2H5(NH2)
Ethylamine.
CH(NH)
Phenylamine (aniline).
The presence of the group (NO2) confers acid properties
upon nitrethane. Its sodium compound, CH*<
NO2
Na
is formed
either by the action of an alcoholic solution of sodium hydrate
on nitrethane, or by the direct action of sodium on the same
body; in the latter case hydrogen is disengaged. Sodium-
nitrethane is very explosive (V. Meyer and Stuber).
When it is sought to prepare potassium-nitrethane by the
action of alcoholic potassium hydrate on nitrethane, the latter
body is decomposed, yielding, among other products, potassium
nitrite. Now, the latter salt exerts a remarkable action on ni-
trethane, giving rise to a new body of complex composition,
potassium ethylnitrolate.
Ethylnitrolic acid may be obtained by a process analogous to
that which has been described for the preparation of methyl-
nitrolic acid. Ethylnitrolic acid contains
CII
C-N.OH
NO2
It crystallizes in light-yellow, transparent prisms, possessing
a feeble bluish fluorescence and a very sweet taste. It decom-
poses without violence at 81-82° into nitrogen, nitrous vapors,
and acetic acid. When boiled with dilute sulphuric acid, it
decomposes into acetic acid and nitrogen monoxide.
CH*O + NO
C2H+N2O3
Ethylnitrolic acid.
Acetic acid.
ETHYL NITRATE, OR NITRIC ETHER.
(C2H5) NO3
This is obtained by the action of nitric acid upon alcohol in
presence of a small quantity of urca. The latter body prevents
the reduction of the nitric acid to nitrous acid. Nitric ether
468
ELEMENTS OF MODERN CHEMISTRY.
condenses in the receiver. It is washed with water, dehydrated
with calcium chloride, and rectified. It is a liquid, having an
agreeable, ethereal odor. It boils at 86°. Density at 0°, 1.1322.
Potassium hydrate decomposes it, like all compound ethers,
forming potassium nitrate and alcohol.
(C²H³)NO³ + KOH
CH.OII + KNO³
It dissolves in ammonia, especially if the latter be warm,
yielding ammonium nitrate and ethylamine. The reaction is
analogous to that of ammonia upon methyl nitrate.
ETHYL CYANATE.
C2H5-N=CO
This compound is prepared by distilling on an oil-bath a
mixture of 2 parts of potassium ethylsulphate and 1 part of
recently-prepared and well-dried potassium cyanate. The pro-
duct which condenses in the receiver is rectified on a water-
bath (Wurtz). Ethyl cyanate is a colorless liquid, having a
very irritating odor. It boils at 60°. Potassium hydrate de-
composes it into carbonic acid gas and ethylamine. It com-
bines with ammonia, developing heat and producing ethylurea
(page 443).
The bodies which have until now been known as cyanic acid
and ethyl cyanate, are only isomerides of the oxygen com-
pounds of cyanogen. They should be named isocyanic acid
and isocyanate of ethyl. The true cyanic ether, (C2H5.O)CN,
or rather a polymeride of that body, has been obtained by
Cloëz. It is formed by the action of cyanogen chloride on
ethylate of sodium.
CNCI + Na.OC2H5
Cyanogen chloride.
Sodium ethylate.
CN.OC2H5 + NaCl
Ethyl cyanate,
Potassium hydrate decomposes the true ethyl cyanate, like
all other compound ethers, into alcohol and the corresponding
potassium salt (cyanate).
ETHYLSULPHURIC, OR SULPHOVINIC ACID.
C2H5
} So+
H
C2H5O
SO2
но
This body is an example of an acid ether. It results from
the substitution of a single ethyl group for one atom of hydro-
gen in sulphuric acid, which is dibasic.
ETHYL CARBONATE.
469
H
H
}}
SO*
C2H5
H>SO¹
It is formed by the action of sulphuric acid upon alcohol.
The mixture of the two bodies becomes hot, and if after cool-
ing the liquid be diluted and saturated with barium carbonate,
an abundant precipitate of barium sulphate will be formed, and
a soluble salt of barium, the ethylsulphate, will remain in solu-
tion. A solution of ethylsulphuric acid may be obtained by
exactly decomposing this salt with dilute sulphuric acid.
By boiling, ethylsulphuric acid is decomposed into sulphuric
acid and alcohol.
C2H5)
H}so +H}
H
C2H5
0 =
H
}
+
H
}
} so.
The ethylsulphates are beautiful salts; they are crystalliz-
able and soluble in water.
C2H5
Ethyl Sulphate.-C SO
CH³ }
C2H5.O
CH.O SO². This
body, which represents sulphuric acid in which the two atoms
of hydrogen are replaced by two ethyl groups, is formed when
vapor of sulphuric anhydride is passed into ether cooled in a
freezing mixture (Wetherill).
(C²H³)²O + SO³ = (CH3)2SO
It is an oily liquid having an acrid taste. Its density is
1.120. It cannot be distilled.
ETHYL CARBONATE.
C2H5
C2H5 CO3
}
C2H5.0
C2H5.0
CO
to 130°. The
A brown mass
The ethyl car-
Ettling obtained this compound by introducing potassium or
sodium little by little into ethyl oxalate heated
metal dissolves, disengaging carbon monoxide.
is obtained, which must be distilled with water.
bonate which passes over is dehydrated with calcium chloride
and distilled.
It may also be obtained by double decomposition by heating
ethyl iodide with silver carbonate.
Ethyl carbonate is a colorless liquid, having a pleasant, ethe-
real odor; its density at 0° is 0.9998, and it boils at 125°.
40
470
ELEMENTS OF MODERN CHEMISTRY.
In the cold, ammonia converts it into ethyl carbamate, or
urethane.
C2H5.0
C2H5.0
>CO
NH3
+
NH2.
C2H5.0
CO
+
C2H5.OH
Ethyl carbonate.
Ethyl carbamate.
It yields urea and alcohol when heated to 100° with am-
monia.
C2H5.0
C2115.0
Ethyl carbonate.
CO + 2NH3
=
CO <NH2
NH2
+ 2C2H5.0H
Urea.
ETHYL CHLOROCARBONATE.
CI
C2H5O
CO
Dumas obtained this ether by passing chlorocarbonic gas
into alcohol. Water is added to the product of the reaction,
and the insoluble liquid is separated, dried, and distilled.
CI
CI
CO + C2H5.OH
Chlorocarbonic gas.
It is a liquid having a pungent,
94°. Hot water decomposes it.
ethyl carbamate, or urethane.
HCI +
CI
Co
C21150 co
Ethyl chlorocarbonate.
ethereal odor. It boils at
Ammonia converts it into
CI
NH2
CO + 2NII3
NH4CI +
CO
C2H5.0
C2I150
SERIES OF SATURATED HYDROCARBONS.
C2H2n+2
For
To methane and ethane, which have already been described,
are related numerous hydrocarbons belonging to the same
series, CnH2n+2. They are called saturated because no hydro-
carbons are known in which the number of hydrogen atoms
exceeds that indicated by the preceding formula. Again, the
hydrocarbons in question can fix directly no other atoms.
example, in order that chlorine can enter into one of their
molecules, hydrogen must first be removed, and this displace-
ment is known to take place, atom for atom, according to the
law of substitution. Thus, if chlorine be made to act upon
the hydrocarbon CH¹ (hexane), the compounds CH¹³Cl,
CH¹²Ñ¹², CH¹¹Cl³, may be obtained successively. Let us con-
sider the first of these compounds, CHCl. The Cl may be
replaced by the group OH, and the chloride is thus converted
14
SATURATED HYDROCARBONS.
471
into an alcohol. For this purpose the chloride is caused to
react with a silver salt, the acetate, for example, and hexyl
acetate is formed by double decomposition.
C6H13CI+ AgC2H3O2
Hexlyl chloride.
Silver acetate.
C6H13.C2H3O2 + AgCl
Hexyl acetate.
Boiling potassium hydrate will transform this ether into
hexyl hydrate.
C6H13. C²H³O² + + KOH
Hexyl acetate.
KC²H³O² + CH¹³.OH
Potassium acetate.
Hexyl hydrate.
This series of reactions permits of the successive transforma-
tion of any hydrocarbon of the saturated series into a chloride,
an acetate, and a hydrate, and the latter is the alcohol corre-
sponding to the hydrocarbon. The following is the series of
saturated hydrocarbons:
CH4
methane.
C2H6 ethane.
C3H8 propane.
C4H10 butanes.
C5H12 pentanes.
C6H14 hexanes.
CH16 heptanes.
C8H18 octanes.
C9H20 nonanes.
C1022 decanes, etc.
All of these hydrocarbons, after the fourth of the series, up
to the term C6H3, have been obtained from petroleum and
the products of distillation of bitumen and peat. Towards
the close of the distillation, when the temperature passes above
300°, the products which distil condense to a solid mass on
cooling. When properly purified, this solid forms a colorless,
translucent mass, which has received the name paraffin. It
is probably a mixture of several hydrocarbons of the series
CnH2n+2. Its point of fusion varies between 45 and 65°.
All of the compounds belonging to this series cannot be
described here, but we may briefly consider their constitution.
The third member of the series, propane, CH8, has the con-
stitution indicated by the formula CH³-CH2-CH³. It is a gas
which liquefies at -17°.
Its superior homologue, butane, CH10, has the constitution
CH³-CH2-CH2-CH³, and can be obtained by the action of
zinc or sodium on ethyl iodide.
2CHI+Na² = 2NaI + C4H10
It is a colorless gas, condensable at +1°. But we have
472
ELEMENTS OF MODERN CHEMISTRY.
here a remarkable instance of isomerism. There is another
butane, isomeric with the preceding, and having the consti-
tution expressed by the formula CH³-CH<
CH³
CH³.
It is tri-
methyl-methane, CH(CH3)3, while normal butane is dimethyl-
ethane, CH (CH3)2, or propyl-methane, CH(CH). The sig-
nification of these words and formulæ is evident. Trimethyl-
methane is methane, CH¹, in which three atoms of hydrogen
are replaced by three methyl groups. The difference in the
atomic grouping is attended by a difference in properties.
Trimethyl-methane is a gas which condenses only at -17°.
The succeeding terms of the series present isomerisms of
the same kind, but much more numerous as their molecular
complication is greater. They need not be described here, since
the same general principles apply to all.
SERIES OF ALCOHOLS.
Ethyl alcohol, of which the more important compounds.
have been briefly described, is not the only product of the fer-
mentation of saccharine liquids. Other alcohols are formed in
small quantity in this reaction, which is conducted on an exten-
sive scale in the arts. Among these alcohols of fermentation
are the following:
Propyl alcohol, or propyl hydrate, C3H7.OH
Butyl alcohol, or butyl hydrate,
Amyl alcohol, or amyl hydrate,
Hexyl alcohol, or hexyl hydrate,
C$119.OH
C5H11.OH
C6H13.OH
Heptyl alcohol, or heptyl hydrate, C7II15.OH
To each of these alcohols correspond numerous ethereal com-
pounds in which the groups propyl, CH', butyl, CH³, amyl,
CH", etc., are substituted for the hydrogen of the hydracids
and oxacids. To each of these alcohols correspond also an
aldehyde and an acid, just as ordinary aldehyde and acetic acid
correspond to ordinary alcohol or ethyl hydrate.
CII3
CH2.OH
CH3
CH3
сно
1
Alcohol.
CH2-CH3
CH2.OH
Aldehyde.
CO.OH
Acetic acid.
CH2-CH3
CH2-CH3
сно
CO.OH
Propyl alcohol.
C3H7
Propyl aldehyde.
C3H7
CH2OH
Butyl alcohol.
сно
Propionic acid.
C3H7
CO.OH
Butyric aldehyde.
Butyric acid.
SERIES OF ALCOHOLS.
473
All of these alcohols contain a group CH2.OH united to a
group or radical, CH+. When they are converted by oxi-
dation into aldehydes and acids, the group CH2.OH is trans-
formed into a group CHO, characteristic of the aldehydes, or
a group CO.OH, characteristic of the acids. These alcohols
are said to be primary. Beginning with butyl alcohol, the
primary alcohols may have several isomeric modifications, as
will be seen shortly. Independently of the primary alcohols,
there are others, isomeric with the preceding, but distinguished
from them by the fact that they do not yield corresponding
aldehydes and acids when oxidized. These iso-alcohols are
divided into secondary, which contain the group CH.OH, and
tertiary, which contain the group C.OH (Kolbe). Without
entering into the details of this subject, we may cite two
examples:
1. By the action of nascent hydrogen upon acetone, Friedel
obtained isopropyl alcohol.
CII3
co + H
CII3
сн.он
CH3
Acetone.
CH3
Isopropyl alcohol.
By oxidation of this iso-alcohol, which is a secondary alcohol
(containing the group CH.OH), acetone is again reproduced.
CH3
CH3
сн.он + о
Сиз
=
H20 + ćo
CH3
2. Boutlerow discovered an isomeride of butyl alcohol, and
named it tertiary butyl alcohol; its constitution is expressed by
the formula
CH3
CHS-C.OH
сиз
This alcohol contains, as is seen, the group C.OH. It yields
neither aldehyde nor acid by oxidation.
In the primary alcohols, the OH is united to a C which is
combined with only one other carbon atom; in the secondary
alcohols, to a C united to two other carbon atoms; while in the
tertiary alcohols, the C to which the hydroxyl is attached is
joined to three other atoms of carbon.
40*
474
ELEMENTS OF MODERN CHEMISTRY.
Propyl Alcohol, C³HO CH³-CH2-CH2.OH.-This was
discovered by Chancel in the oily liquid remaining after the dis-
tillation of brandy. It is a spirituous liquid, boiling at 98°.
Its iodide, C³H'I, boils at 104.5° (I. Pierre and Puchot).
The isopropyl alcohol of Friedel is formed under the circum-
stances just indicated. Its constitution is expressed by the
formula
CH³-CH.OH-CH³
It boils at 86°. When propylene gas is heated with hydri-
bodic acid, isopropyl iodide, CH'I, is obtained, boiling at 92°.
6
C³H + HI
Propylene.
CHI
Isopropyl iodide.
Silva has described numerous derivatives of isopropyl alco-
hol.
Butyl Alcohols, C4H10O.-The constitution of the butyl
alcohol of fermentation, which is a primary alcohol, is expressed
by the formula CH³>CH-CH².OH. It is isobutyl alcohol.
CH3
In 1852, Wurtz obtained it from the fusel-oil from the rec-
tification of beet-root alcohol. It is a colorless liquid, having
a penetrating odor analogous to that of amyl alcohol, but more
spirituous. It dissolves in 10.5 times its volume of water. It
boils at 109°, and yields on oxidation an acid isomeric with
butyric acid and called isobutyric.
It may be regarded as ordinary alcohol in which two atoms
of hydrogen are replaced by two methyl groups.
CH3
CH2.OH
Alcohol.
CH(CH3)2
CH2.OH
Isobutyl alcohol.
Lieben discovered normal butyl alcohol, isomeric with the
alcohol of fermentation, and which yields butyric aldehyde and
butyric acid by oxidation. He obtained this alcohol by the
action of sodium amalgam in presence of water on butyral
(butyric aldehyde).
C3H7
CHO
Butyral.
+ H2
C3H7
CH2.0п
Normal butyl alcohol.
De Luynes obtained another isomeride of butyl alcohol by
the reduction of erythrite (page 565). This alcohol is second-
ary, having the constitution CH³-CH2-CH(OH)-CH³. It
SERIES OF ALCOHOLS.
475
boils at 116.9° (Lieben). The corresponding iodide, CH³-
CH2-CHI-CH³, boils at 118°. It is formed by the following
reaction :
CH¹00+ 7HI
CHO*
Erythrite.
C4H9I + 4H³0 + 31²
Secondary butyl iodide.
The tertiary butyl alcohol discovered by Boutlerow has re-
ceived the name trimethylcarbinol, on account of its constitu-
tion, which has already been indicated. It is a well-crystallized
compound, melting between 20 and 25°.
In conclusion, four alcohols are known having the composi-
tion C'H¹O, and presenting a remarkable instance of isomer-
ism. Their constitutions are again indicated in the following
formulæ :
CH3
CH3
сна-с.он
CH3
CH³-CH
CH3
C
сна
CH2.OH
сн.он
I
сиз
CH3
Primary isobutyl
Secondary butyl
Tertiary butyl
alcohol.
(Wurtz.)
сна
сна
CH2.OH
Normal primary
butyl alcohol.
(Lieben.)
alcohol (fermentation).
alcohol.
(De Luynes.)
Amyl Alcohol of Fermentation.-CHO-
(Boutlerow.)
CH³
CH³>CH-
CH2-CH2.OH. This is the most abundant constituent of
fusel-oil from beet-root and potatoes, as well as of that from
the mare of grapes, from whiskey, etc. These products are
only the residues of the distillation of alcohol from various
sources.
Amyl alcohol is a colorless liquid, having a rather unpleasant
odor. It boils at 132°. Its density at 15° is 0.8184. It is
nearly insoluble in water. It turns the plane of polarization
to the left. There is, nevertheless, an amyl alcohol which has
no action upon polarized light, and which Pasteur has named
inactive amyl alcohol. The latter boils at 130°. It is iso-
meric with the amyl alcohól of fermentation, from which it
differs in physical properties, but presents the same composi-
tion and the same chemical properties. It is a case of physical
isomerism.
When submitted to the action of zinc chloride, amyl alcohol
is converted into amylene and polymerides of that body (di-
amylene, C¹ºH20, triamylene, C¹5H30).
C5H120
Amyl alcohol.
C³H¹º + H2O
Amylene.
476
ELEMENTS OF MODERN CHEMISTRY.
By oxidation, amyl alcohol yields valeric aldehyde and val-
eric acid.
C³H¹²0 + 0 = H³0 +
C5H10O
C³H¹²0 +0² H2O +
Valeral, or valeric aldehyde.
C5H1002
Valeric acid.
The numerous amylic ethers cannot be described here.
Amyl oxide, (CH)O, is a colorless liquid, having a suave
odor, and boiling at 176° (Williamson).
Amyl chloride, CH"Cl, is a colorless liquid of an aromatic
odor, boiling at 102°.
Amyl iodide, CHI, is a colorless liquid, which becomes.
brown when exposed to the light. Density at 0°, 1.4676.
Boiling-point, 147°.
Isomerides of Amyl Alcohol.-At least five alcohols are
known having the composition of amyl alcohol. Independ-
ently of the normal alcohol CH³-CÙ²-CH²-CH²-CH².OH
(boiling-point, 137°), which Lieben obtained by the action of
nascent hydrogen on valeral (valeric aldehyde), and the alco-
hol of fermentation which has just been described, and which
may be called isopropyl-ethyl alcohol,
CH³
CII3
CH-CH2-CH2.OH
=
CII2(C3H7)i
CII2.0
there are three others having the composition CH2O. The
most important is the compound which is generally called hy-
drate of amylene, because it breaks up very readily into water
and amylene. It is a tertiary alcohol of the form
CH3
CH3
C.OH-CH2-CH3
Its corresponding iodide is formed by direct union of hydri-
odic acid and the amylene prepared by the action of zinc
chloride upon amyl alcohol of fermentation (A. Wurtz).
CH* + HI = CH¹¹I
This iodide boils at 129°. By treating it with water and
silver oxide, Wurtz obtained the alcohol which he named
hydrate of amylene. The latter liquid boils at 105°. It is
decomposed by heat alone into amylene and water, according
to the equation before given. The other isomerides of amyl
alcohol need not be described.
SERIES OF ALCOHOLS.
477
Hexyl and Heptyl Alcohols.-Faget announced that the
residues from the distillation of fusel-oil from fermented grape-
juice contained a small quantity of hexyl (CH¹¹O) and heptyl
(C'H¹O) alcohols, but such alcohols have not been refound
in that product.
Normal hexyl alcohol has been obtained from the volatile
oil of the seeds of Heracleum giganteum, an oil which contains
butyrate of hexyl, CH13.CHO². The normal alcohol boils.
at 157-158°.
Normal heptyl alcohol, C'HO, has been prepared by the
action of nascent hydrogen on oenanthic aldehyde C'H¹O.
It boils at 175-177°, and has an aromatic odor.
Octyl Alcohols, CH¹8O.—Normal octyl alcohol may be ex-
tracted from the seeds of Heracleum spondylium and Hera-
cleum giganteum, in which octyl acetate, CH¹.C²H³O², exists.
This ether is separated and decomposed by boiling potassium
hydrate. Its boiling-point is between 190 and 192°.
Bouis discovered secondary octyl alcohol. By boiling one.
of the acids produced by the saponification of castor-oil, rici-
nolic acid, with potassium hydrate, Bouis decomposed it into
sebacic acid and a new secondary alcohol. This is octyl alco-
hol, CH¹80, a colorless liquid having a pleasant, aromatic odor,
and boiling at 178°. The following equation explains its
formation:
C18H3403 + 2KOH
Ricinolic acid.
K²C¹ºH¹60 + C³H¹³O + H²
Potassium sebate. Octyl hydrate.
Cetyl Alcohol.-The concrete portion of an oil which fills
the cranial sinuses of the sperm-whale is called spermaceti.
When properly purified it occurs in beautiful pearly plates,
fusible at 49°. It is a compound ether of which the nature
was recognized by Chevreul in 1823. By submitting it to the
action of potassium hydrate, that chemist decomposed it into
palmitic acid and a new alcohol which he called ethal, to denote
its relations with alcohol and ether. It is now called cetyl
alcohol, or cetyl hydrate.
C16H1310
C16H33
+ KOH
Cetyl palmitate.
C16H33.OH + KC16H3102
Cetyl hydrato. Potassium palmitate.
It belongs to the same homologous scries as the preceding
alcohols.
Alcohols from Wax.-The most complex alcohols of the
series under consideration were obtained from wax by Brodie.
478
ELEMENTS OF MODERN CHEMISTRY.
Ordinary beeswax is a mixture of a fatty acid, C²7H5¹O², called
cerotic acid (cerin), and a compound ether, the palmitate of
myricyl (myricin). The two bodies are separated by alcohol,
which readily dissolves the first, but in which the second is but
slightly soluble. By boiling the palmitate of myricyl with
potassium hydrate, it breaks up into palmitic acid and hydrate
of myricyl, or myricyl alcohol, C¹³0H62O.
130
Chinese wax is a compound ether; it is cerotate of ceryl, and
may be decomposed by caustic potassa into cerotic acid and
ceryl hydrate, or ceryl alcohol, C7H56O. The hydrates of cetyl
and ceryl are solid bodies.
ALLYL ALCOHOL.
C3H5.OH =CH2-CH-CH2.OH
All of the alcohols thus far considered belong to the series
CnH2n+20. There are other monatomic alcohols which belong
to different series, that is, in which there are different relations
between the number of hydrogen atoms and the number of
carbon atoms. Among these other alcohols, the most impor-
tant is allyl alcohol, or hydrate of allyl, so named because it is
closely related to the essential oil of garlic, which is allyl sul-
phide. Another natural oil, that of mustard, is sulphocyanate
of allyl.
C3H5.OH
Allyl hydrate.
(CH)2S
Allyl sulphide.
C3H5.CNS
Allyl sulphocyanate.
Hofmann and Cahours prepared allyl hydrate and a great.
number of its derivatives artificially by the aid of allyl iodide,
CH³I, which is formed when glycerin is acted upon by iodide
of phosphorus, PI (Berthelot and de Luca). This iodide,
whose relations to allyl alcohol are the same as those of ethyl
iodide to ordinary alcohol, is a colorless liquid, having a slightly
pungent, garlicky odor, and boiling at 101°.
When heated with mercury and concentrated hydrochloric
acid, it yields pure propylene gas (Berthelot).
6
2CHI+ 2HCl + 4Hg = 2C³II + Hg²I² + Hg²Cl²
Allyl iodide.
Propylene.
Tollens and Henninger discovered a very simple process for
the preparation of allyl alcohol. It consists in heating formis
acid, or oxalic acid, from which the former acid is produced,
with glycerin to 220°. The allyl alcohol which distils is
COMPOUND AMMONIAS.
479
washed with a concentrated solution of potassium carbonate,
and rectified over lime. In this reaction, a monoformine of
glycerin is first produced, and this decomposes at 220° into
carbon dioxide, water, and allyl alcohol.
0.CHO
C3H5 OH
ΟΗ
Monoformine of glycerin.
CO2 + H20 + C3H5.OH
Allyl alcohol.
It will be seen that the reaction is really a reduction.
Allyl alcohol is a colorless liquid, boiling at 97°, and having
a pungent, alcoholic odor. It dissolves in all proportions of
water. Density at 13°, 0.86.
Allyl alcohol is an unsaturated compound; it can fix directly
two atoms of hydrogen, chlorine, or bromine, or one molecule
of hydrobromic acid, etc.
Acrolein, a volatile liquid that is formed in the distillation
of fatty bodies, is the aldehyde of allyl alcohol. Acrylic acid
is the corresponding acid.
COMPOUND AMMONIAS, OR AMINES.
Wurtz gave these names to the basic combinations resulting
from the substitution of alcoholic radicals, such as methyl,
ethyl, etc., for the hydrogen of ammonia. This substitution
may be more or less complete; 1, 2, or 3 atoms of hydrogen
may be replaced by as many alcoholic groups. Hence there
are various classes of amines; they are designated by the names
primary, secondary, and tertiary.
PRIMARY AMINES.
SECONDARY AMINES. TERTIARY AMINES.
CH3
CIN
H
Dimethylamine.
H
HN
H
Ammonia.
CH3
IIN
II
Methylamine.
€22115
IN
Ethylamine.
C2115
C2115 N
II
Diethylamine.
CII3
CH3 N
CH3
Trimethylamine.
C2115
CIEN
C2H5
Triethylamine.
Lastly, bases are known which are the most energetic of
all, and may be considered as derived from the hypothetical
hydrate of ammonium by the substitution of alcoholic radicals
for 4 atoms of hydrogen.
480
ELEMENTS OF MODERN CHEMISTRY.
H
H
N.OH
H
H
C2H5
C2H5
N.OH
C2H5
C2H5
Ammonium hydrate.
Hydrate of tetrethylammonium.
The latter ammoniated bases, as well as the secondary and
tertiary amines, were discovered by Hofmann.
In the amines, nitrogen acts as a triatomic element or tri-
valent; but it may assume two other atomicities. In sal-
ammoniac, it is pentatomic, and it may play precisely the same
part in the amines.
H
N
H H
Ammonia.
C2H5
N
Cl
(OH)'
H II (C2H5)' (C2H5)'
N
N
H H
Ammonium
(C2H5)' (C2115)'
chloride.
C2H5 C2H5
Triethylamine.
Tetrethylammonium
hydrate.
Related to the amines are various organic combinations
which have the same constitution, but in which the nitrogen
is replaced by an analogous element, such as phosphorus,
arsenic, or antimony. A great number of these bodies have
been discovered, of which the more important are
C2H5
C2H5 P
C2H5
Triethylphosphine.
C2H5
C2H5 As!!!
C2H5
Triethylarsine.
C2H5
C2H5 Sb
C2H5
Triethylstibine.
The nitrogenized bases that have just been considered belong
either to the type NX3 or to the type NX5. A new class of
compounds has recently been discovered, belonging to the type
N2X+.
It is evident that the group NX² (amidogen) cannot exist
in the free state. If it could be isolated, it would probably
combine with itself, forming a double molecule
N2H4=
NH2
NH2
Fischer has made known several substituted derivatives of
this body, N2H+, which he names hydrazine. He has described
ethylhydrazine, NH-NH (CH³). It is a base soluble in
water, and having an ammoniacal odor; its hydrochloride con-
tains N'H³(C2H5). 2HCl.
3
The compound ammonias cannot all be described here; we
need only consider the more important.
METHYLAMINE.
481
METHYLAMINE.
CH5N
CH3
HN
H
This body may be prepared by boiling together potassium
hydrate and methyl cyanate or cyanurate, and passing the
vapors which are disengaged into dilute hydrochloric acid;
methylamine hydrochloride is thus formed.
CO
CH37
CH3
N+ 2KOH
===
Methyl cyanate.
K2CO3 + HN
H
Methylamine.
The solution is evaporated to dryness, and the residue fused
and allowed to cool; it is then mixed with double its weight
of powdered quick-lime, and the mixture gently heated. The
methylamine disengaged may be collected over mercury.
It is a colorless gas, which condenses to a light liquid at a
temperature a few degrees below 0°. It is inflammable, and
burns with a pale flame. Its odor is strongly ammoniacal and,
at the same time, recalls that of the sea. It is the most solu-
ble of all gases.
1 volume of water at 12.5° absorbs 1153
volumes of methylamine. The aqueous solution possesses the
odor of the gas, a caustic taste, and a strong, alkaline reaction.
Like ammonia, it precipitates the oxides from solutions of the
metallic salts.
If a solution of methylamine be added to a solution of cupric
sulphate, a light-blue precipitate is first formed, but disappears.
if an excess of methylamine be added, yielding a beautiful blue
solution.
Methylamine Hydrochloride, CH N.HCl, differs from am-
monium chloride by its solubility in boiling alcohol, from which
it is deposited on cooling in large, colorless, deliquescent plates.
With platinic chloride it forms a yellow precipitate, soluble in
boiling water, from which it crystallizes in golden-yellow scales.
It is a chloroplatinate, (CH³N.HCl)².PtCl¹.
DIMETHYLAMINE, TRIMETHYLAMINE, TETRA-
METHYLAMMONIUM HYDRATE.
These compounds were discovered by Hofmann.
Dimethylamine, (CH3)2NII, is a combustible gas which lique-
fies at 8°.
▼
41
482
ELEMENTS OF MODERN CHEMISTRY.
Trimethylamine, (CH3)3N, exists ready formed in the Cheno-
podium vulvaria, in the flowers of Crataegus oxyacantha, in
herring-brine, in cod-liver oil, and in coal-gas tar. Vincent
extracts large quatities of it from the residues of the distilla-
tion of fermented beet-juice.
At ordinary temperatures it is a gas; it liquefies at 9°. It is
very soluble in water and in alcohol. It has a strong, ammoniacal
odor, and an intense, alkaline reaction. It unites directly with
methyl iodide, forming the iodide of tetramethylammonium.
(CH3)3N + CH*I = (CH3)NI
This iodide possesses all the appearances of a salt. It is
soluble in water, and the solution treated with silver oxide yields
silver iodide and tetramethylammonium hydrate.
2(CH³)*NI + Ag²0 + H³0 = 2AgI + 2(CH³)¹N.OH
The latter body is very soluble in water, and the solution is
caustic. When submitted to dry distillation, it decomposes into
trimethylamine and methyl alcohol.
(CH³)¹N.OH = CH³.OH + (CH³)³N
ETHYLAMINE.
C2H'N
C2H5
HN
H
Ethylamine is prepared by a process analogous to that which
yields methylamine; cyanate or cyanurate of ethyl is decom-
posed with boiling potassium hydrate, and the vapors are con-
densed in very dilute hydrochloric acid. The dry ethylamine.
hydrochloride is then treated with quick-lime (A. Wurtz).
Another process has been indicated by Hofmann. It consists
in causing ammonia to react upon the bromide or iodide of
ethyl.
H
C2H5Br + H N
H
C2H5
HN.HBr
H
Ethylamine hydrobromide.
Ethylamine is a light, mobile, colorless liquid; it boils at
18.7°. Its odor is strong and exactly resembles that of am-
monia.
Ethylamine is inflammable. It mixes with water, alcohol,
and ether in all proportions. Its aqueous solution is caustic,
and precipitates most of the metallic salts like solution of am-
ETHYLPHOSPHINES.
483
monia, and, like the latter, redissolves cupric hydrate, forming
a blue liquid.
Ethylamine Hydrochloride, CH'N.HCI.-This salt crys-
tallizes in large, deliquescent plates, soluble in absolute alcohol.
Its aqueous solution yields with platinic chloride a precipitate
composed of yellow scales, soluble in boiling water, and consti-
tuting a chloro-platinate, (C'H'N.HCI). PtC.
DIETHYLAMINE, TRIETHYLAMINE, TETRETHYL-
AMMONIUM HYDRATE.
C2H5
Diethylamine, C2H5N, was obtained by Hofmann by heat-
H
ing ethylamine with ethylbromide, and decomposing the die-
thylamine hydrobromide formed by an alkali.
C2H5
HN + C2H5Br
H
Ethylamine.
C2H5
C2115 › N.HBr
II
Diethylamine hydrobromide.
The free base is a liquid having an ammoniacal odor and
boiling at 57.5°
Triethylamine may be formed by the action of ethyl bro-
mide on diethylamine; triethylamine hydrobromide is formed,
C2H5
C2H5N.HBr, from which alkalies cause the disengagement
C2H5
of triethylamine, a colorless liquid, boiling at 91°; its odor
is ammoniacal and its reaction strongly alkaline.
Tetrethylammonium Hydrate.-When a mixture of ethyl
iodide and triethylamine is heated on a water-bath, the two
bodies combine, forming the compound which Hofmann has
named tetrethylammonium iodide.
C2H³I
Ethyl iodide.
+
(C2H³) N
Triethylamine.
(C2H5) ¹N.I
Tetrethylammonium iodide.
When this is treated with silver oxide and water, it yields
silver iodide and tetrethylammonium hydrate, (CH) N.ÕH, a
powerful base, which is crystallizable and soluble in water. Its
energy is comparable to that of potassium hydrate.
ETHYLPHOSPHINES.
Primary, secondary, and tertiary ethylphosphines are known,
as well as the compounds of tetrethylphosphonium.
484
ELEMENTS OF MODERN CHEMISTRY.
C2H5
H
Р
H
C2H5
C2H5 P!!!
H
C2H5
C2H5
C2H5
V
C2H5 P!!!
P-
C2H5
C2H5
C2H5
Ethylphosphine. Diethylphosphine. Triethylphosphine. Tetrethylphosphonium.
(Primary.)
(Secondary.)
(Tertiary.)
The first two have been recently discovered by Hofmann. The
third is due to an admirable research of Hofmann and Cahours,
who obtained it by the action of phosphorus trichloride on zinc
ethyl.
2PC1³ + 3[Zn(CH)"]
Zinc ethyl.
2[P(C²H³)³]
Triethylphosphine.
+ 3ZnCl2
The operation must be conducted out of contact with the
air, and the zinc ethyl must be diluted with anhydrous ether.
Monethylphosphine and diethylphosphine are produced when
ethyl iodide is made to react upon phosphonium iodide, PH*I,
hydriodide of hydrogen phosphide (page 167), in presence of
an excess of zinc oxide.
2C2H5 + 2PII¹I + ZnO 2[(C2H5) H2P.HI] + ZnI² + H2O
2C2H51 + PHI + ZnO (C2H5)2HP.HI + ZnI² + H20
As both reactions are accomplished simultaneously, both
phosphines are obtained at the same time. They are separated
by the action of water upon the two hydriodides which are
formed. That of monethylphosphine is decomposed by water,
while that of diethylphosphine is only decomposed by the alka-
lies. It is sufficient then to add water to the product of the
reaction in order to set free the monethylphosphine; when
the latter has been completely expelled by heat, potassium hy-
drate added to the residue will cause the disengagement of the
diethylphosphine. These operations should be conducted in a
current of hydrogen.
Monethylphosphine, (CH) H'P.-This is a colorless liquid,
lighter than water, in which it is insoluble, and boiling at 25°.
It has a most disagrecable odor. It takes fire on contact with
chlorine or nitric acid. Its hydriodide crystallizes in beautiful,
white, quadrangular tables.
Diethylphosphine, (C²H³)2HP.-A colorless liquid, lighter
than water, and boiling at 85°. It is very avid of oxygen, and
sometimes takes fire spontaneously on contact with the air.
Triethylphosphine, (CH) P.-This is a colorless liquid,
boiling at 127.5°. Density at 15°, 0.812. It combines di-
rectly with oxygen, forming triethylphosphine oxide, (C2H5)³PO.
The latter is a crystalline solid, very soluble in water and in
alcohol. It distils at 240°.
PRODUCTS OF OXIDATION OF ETHYLPHOSPHINES. 485
When treated with ethyl iodide, triethylphosphine yields
tetrethylphosphonium iodide, (C2H5) PI, a compound which
may be obtained in beautiful crystals. When this iodide is
acted upon by moist silver oxide, it furnishes the corresponding
hydrate, which is an energetic base.
2[(C²H³)¹PI] + Ag²0 + H2O = 2AgI + 2[(C²H³)¹P.OH]
Tetrethylphosphonium
iodide.
Tetrethylphosphonium
hydrate.
PRODUCTS OF OXIDATION OF ETHYLPHOS-
PHINES.
When the ethylphosphines are treated with fuming nitric
acid under suitable conditions, they act in a characteristic man-
ner. Monethylphosphine is transformed into a dibasic acid,
monethylphosphinic; diethylphosphine yields a monobasic acid,
diethylphosphinic. Triethylphosphine yields an indifferent
oxide, which has already been mentioned. Now, if it be remem-
bered that under the same circumstances hydrogen phosphide
furnishes phosphoric acid, it will be seen that the preceding
oxidation compounds may be regarded as phosphoric acid, in
which 1, 2, or 3 groups OH are replaced by as many ethyl
groups.
H
PII
H
Hydrogen phosphide.
C2H5
PH
H
Monethylphosphine.
C2115
{
ΟΙ
PO OI
OII
Phosphoric acid.
C2115
РО ОН
{
OH
Monethylphosphinic acid.
##
P C2H5
H
Diethylphosphine.
C2H5
P C2115
C2I15
Triethylphosphine.
PO
{
C2115
C2H5
ΟΙ
Diethylphosphinic acid.
C2H5
PO C2H5
C2H5
Triethylphosphine oxide.
The compounds of arsenic and ethyl are entirely analogous
to the phosphines; they have already been alluded to. Besides
these, there are ethylic combinations corresponding to cacodyl
and its derivatives.
41*
486
ELEMENTS OF MODERN CHEMISTRY.
ORGANO-METALLIC COMPOUNDS.
ZINC-ETHYL.
Zn''(C2H5)2
One of the more important of the compounds formed by the
union of the metals with alcoholic radicals is zinc-ethyl, dis-
covered by Frankland.
It is prepared by heating ethyl iodide with zinc-turnings
and a small quantity of sodium on a water-bath. Zinc iodide
and zinc-ethyl are formed. When the reaction is terminated,
the product is distilled and that portion collected which passes
above 115°.
Zinc-ethyl is a colorless, mobile, and highly-refractive liquid.
It has a peculiar, penetrating, and very disagreeable odor. It
boils at 118°. It takes fire spontaneously on contact with the
air, burning with a green flame, and producing white fumes
of zinc oxide.
If water be added to a small quantity of zinc-ethyl contained
in a tube, a brisk effervescence at once takes place, and a white
deposit is formed. The gas is ethane, and the deposit is zinc
hydrate.
Zn(C2H5)² + 2H2O = Zn(OH)2+2C2H6
Zinc-ethyl will enter into double decompositions.
By the action of phosphorus trichloride on this body, Hof-
mann and Cahours obtained triethylphosphine and zinc chloride.
There is a zinc-methyl, Zn(CH), corresponding to zinc-
ethyl.
MERCUR-METHYL AND MERCUR-ETHYL.
These compounds were obtained by Frankland and Duppa,
by the action of methyl and ethyl iodides on sodium amalgam
(sodium 1, mercury 500), in presence of a small quantity of
acetic ether.
Mercur-ethyl is a colorless, inflammable liquid, insoluble in
water. Density, 2.44. Boiling-point, 158-160°. It is one
of the most dangerous bodies known. The inhalation of its
vapor for any length of time, even in small quantity, will
produce fatal poisoning.
STANNETHYLS.
487
Chlorine, bromine, and iodine instantly decompose mercur-
ethyl with formation of a compound of mercur-monethyl.
C2H5
Hg { CH®
(C²H³ + I²
Mercur-ethyl.
C²H³I + Hg{ ( C2H5
I
Ethyl iodide. Mercur-monethyl iodide.
STANNETHYLS.
The discovery of the numerous compounds of tin and ethyl
is due to Löwig. Their history has been completed by Frank-
land, Cahours, and Riche.
As the nomenclature and constitution of the stannethyls
have already been indicated (page 424), we need only consider
a few of these interesting compounds.
Stannodiethyl, Sn(CH).-The iodide of this compound
is obtained when ethyl iodide is heated with tin-filings to about
180°. This iodide, Sn(CH³)'I', purified by crystallization in
alcohol, furnishes free stannodiethyl when its solution is treated
with zinc, which removes the iodine.
Stannodiethyl is an oily, yellow liquid, which does not vola-
tilize without decomposition.
When heated to 150° it begins
to boil, but the greater part of it is decomposed into stanno-
tetrethyl and tin.
2[Sn(C²H³)²] = Sn(CH³) + Sn
The iodide of stannodiethyl crystallizes in pale yellow needles.
In its solution, the alkalies precipitate the oxide Sn(C²H³)20,
which forms an amorphous, white precipitate, insoluble in water
and alcohol, but soluble in the alkalies and acids with which it
forms salts.
Stannotriethyl or Sesquistannethyl, Sn²(C2H5)=(C²H³)³
Sn-Sn(C²H³)³.—This is formed, together with the preceding
compound, by the reaction of ethyl iodide on an alloy of tin and
sodium. It is separated by fractional distillation; it boils between
265 and 270°. It plays the part of a radical and combines
directly with oxygen. The oxide contains Sn²(C2H5)O =
[Sn(CH³)³]O. It combines with the elements of water, form-
ing a hydrate, Sn(CH3)3.OH, crystallizable in prisms. These
crystals are fusible at 44°. The oxide distils at 272°. It
reacts with the acids to form crystallizable salts.
[Sn(CH³)³]2O + 2HNO3 = 2[Sn(CH).NO³] + H2O
Stannotriethyl oxide.
Stannotriethyl uitrate.
488
ELEMENTS OF MODERN CHEMISTRY.
The iodide, Sn(CH) I, is a liquid having a mustard-like
odor, and distilling without decomposition towards 235-238°.
Density at 15°, 1.833.
Stannotetrethyl, Sn(C²H³).—Colorless liquid, almost odor-
less, and boiling at 181°. Density, 1.187. It is formed by
the action of zinc ethyl on stannodiethyl iodide.
Sn(C²H³)²I² + Zn(C²H³)²
Stannnodiethyl iodide.
Zinc-ethyl.
2
Sn(C2H5) + ZnI²
Stannotetrethyl.
It is a saturated compound, and does not enter into combi-
nation, but by the action of energetic reagents it yields com-
pounds of stannodiethyl or stannotriethyl. Thus, with iodine,
the following reaction takes place :
Sn(C²H³)+ + I² = Sn(C²H³)³I + C²H³I
VOLATILE FATTY ACIDS DERIVED
FROM THE ALCOHOLS.
Modes of Formation and Constitution.-These acids result
from the oxidation of the alcohols of which the principal com-
pounds have been described. They are formed in a great num-
ber of reactions, and many of them exist already formed in
nature, either in the free state or in combination in neutral
fatty compounds, that is, the oils and fats.
Their composition is expressed by the general formula CnH2n
O²; they contain one more atom of oxygen and two atoms of
hydrogen less than their corresponding alcohols.
Their principal modes of formation are as follows:
1. By oxidation of an alcohol:
CH*O + O
+
Methyl alcohol.
CH2O2 + H2O
Formic acid.
2. By oxidation of an aldehyde:
C²H¹O +0
Aldehyde.
C2H4O2
Acetic acid.
3. By the decomposition of an organic cyanide with boiling
potassium hydrate:
CH
ON
+ KOH + H2O
Methyl cyanide.
CH³
COOK + NH
Potassium acetate.
3
VOLATILE FATTY ACIDS.
489
The acetic acid is formed in this last reaction, by the union
of the carbon of the cyanogen group with the oxygen of both
the potassium hydrate and the water, the hydrogen of these
two bodies combining with the nitrogen of the cyanogen to
form ammonia. It may then be admitted that acetic acid con-
tains a radical carbonyl, CO, united on the one hand with a
methyl group (that of the methyl cyanide), and on the other
with a hydroxyl group, OH.
The other acids of the series possess an analogous constitu-
tion.
CH3
со.он
Acetic acid.
C2H5
со.он
Propionic acid.
C3H7
CO.OH
C4H9
CO.OH etc.
Butyric acid.
Valeric acid.
4. A method of synthesis, discovered by Wanklyn, furnishes
a direct support to this theory of the constitution of the fatty
acids. That chemist realized the synthesis of acetic and pro-
pionic acids by passing a current of carbonic acid gas over
sodium-methyl and sodium-ethyl, organo-metallic compounds
which result from the action of sodium upon zinc-methyl and
zinc-ethyl.
NaCH³ + CO.0
Sodium-methyl.
NaC2H5 + CO.O
Sodium-ethyl.
CH3
co.oNa ૧.
Sodium acetate.
C2H5
I
CO.ONa
Sodium propionate.
General Properties.-1. The volatile fatty acids of the series.
CnH2O² are monobasic; each contains one atom of hydrogen
which may be replaced by an equivalent quantity of a metal.
2. When submitted to dry distillation, many of their salts
yield an acetone and a carbonate.
CH3
CH3-CO.O
CH3–CO.O
Ca"
co
+ CaCO3
Сиз
Calcium acetate.
Acetone. Calcium carbonate.
3. The same reaction may produce an aldehyde and a hydro-
carbon of the series CH² (Chancel).
2n
(C³H™-C0.0)²Ca
Calcium butyrate.
C3H7
сно
Butyral, or butyric
aldehyde.
+ C3H6 +
CaCO3
Propylene.
V*
490
ELEMENTS OF MODERN CHEMISTRY.
4. When a mixture of a salt of a fatty acid and a formate
is subjected to dry distillation, the principal product of the
reaction is an aldehyde (Piria).
CH3-CO.OK +
H-CO.OK
Potassium acetate.
Potassium formate.
CH3
+
K2CO3
сно
Aldehyde.
5. The fatty acids are converted into chlorides by the action
of phosphorus pentachloride, or oxychloride (Gerhardt).
C2H30.0K
Potassium acetate.
+ PC15
C21130.CI + POCI3 + KCI
Acetyl chloride. Phosphorus
oxychloride.
6. By the action of these chlorides upon the salts of the
fatty acids, the anhydrides of the acids are formed (Gerhardt).
C2H3O
K
}
0 + C2H3.OCI
Potassium acetate. Acetyl chloride.
KCI
+
C2H30
0
C2H3O
Acetic anhydride.
7. When subjected to the action of phosphoric anhydride,
the ammonium salts of these acids lose 2H2O and are con-
verted into nitriles or cyanogen ethers (Dumas, Malaguti and
Le Blanc, Frankland and Kolbe).
CH3
60.0(NH4)
Ammonium acetate.
CH3
2H20
+
CN
Acetonitrile.
(Methyl cyanide.)
FORMIC ACID.
CH202
This acid, which was discovered by S. Fischer in 1760, in
red ants, is formed in a great number of reactions, particularly
in the oxidation of methyl alcohol, in the decomposition of
hydrocyanic acid by acids or alkalies, in the distillation of oxalic
acid, and in the oxidation of many organic matters, such as
starch, sugar, etc. Berthelot achieved its direct synthesis by
heating carbon monoxide for a long time to 100° in sealed
flasks containing a concentrated solution of potassium hydrate.
CO + KOH
HCO.OK
Potassium formate.
Preparation.-Starch, manganese dioxide, and dilute sul-
phuric acid may be boiled together in a capacious retort, and
the acid liquid which condenses in the receiver saturated with
lead carbonate. Lead formate is thus obtained, and is purified
FORMIC ACID.
491
by crystallization. To obtain formic acid, the salt is heated in
a current of dry hydrogen sulphide. Formic acid distils
(Döbereiner).
Another and better process consists in heating to 100° equal
parts of oxalic acid and glycerin. Under these conditions,
the oxalic acid breaks up into carbonic acid gas, and formic acid
which distils. The liquid is saturated with lead carbonate, and
the preparation concluded as before (Berthelot).
Properties. Formic acid is a colorless liquid, having a
pungent odor and a very acid taste. It boils at 99°, and solid-
ifies to a crystalline mass at 8.5°. It mixes with water in all
proportions.
If an excess of sulphuric acid be added to a small quantity
of formic acid contained in a test-tube, and a gentle heat be
applied, a regular disengagement of gas will take place; it may
be ignited at the mouth of the tube, and will burn with a blue
flame.
It is carbon monoxide, and is formed according to the fol-
lowing equation:
CH*O = CO +HẢO
If formic acid be added to a solution of silver nitrate, and
the liquid be heated, it will soon become clouded; silver will
be precipitated as a gray powder, and carbon dioxide will be
disengaged.
The formic acid becomes oxidized in reducing the silver
nitrate,
CHO + 0 = CO2 + H*O
Chlorine determines an analogous decomposition.
CH20² + Cľ² CO² + 2HCI
Formates. Formic acid is an energetic acid, perfectly neu-
tralizing the bases. It is monobasic; one of its hydrogen
atoms can be replaced by an equivalent quantity of metal. The
formates are soluble; the most characteristic are cupric for-
mate, Cu(CHO²)2+4H2O, which crystallizes in magnificent,
oblique rhombic prisms, and lead formate, Pb(CHO²)², which
forms long, colorless needles, slightly soluble in cold water.
Ammonium formate, which is obtained by saturating formic
acid with ammonia, crystallizes in prisms which are very solu-
ble in water. When quickly heated to about 200°, it breaks
up into hydrocyanic acid (formonitrile) and water (Pelouze).
(NH*)CHO = 2HO + CNH
492
ELEMENTS OF MODERN CHEMISTRY.
FORMIC ALDEHYDE.
CH2O = H-CHO
Hofmann has recently obtained this body by the slow com-
bustion of methyl alcohol, brought about by a spiral of platinum
wire.
CH*O+0 = HẢO + CH’O
It is also formed in the distillation of barium and calcium
formates. It is not known in the pure state.
It has a great
tendency to become polymerized, forming a solid compound,
which Boutlerow has named trioxymethylene, and which prob-
ably contains CH6O³.
ACETIC COMBINATIONS.
It may be admitted that these compounds contain the mon-
atomic radical acetyl (CHO) = (CH³-CO)', which may be
regarded as oxidized ethyl.
CH3
CH³
(C2H30)' -co
-CO
(C²H³)' =_ĊH²
Ethyl.
Acetyl.
Aldehyde is the hydride of this
radical; acetic acid is its
Besides these, there are
hydrate, and acetone its methylide.
known the oxide and chloride of acetyl, an acetyl ammonia,
which is acetamide, etc.
The following formulæ indicate the relations between all of
these bodies:
C2H3O.H
Acetyl hydride (aldehyde).
C2H3O.CI
Acetyl chloride.
C2H3O.CH³
Acetyl methylide (acetone).
C2H3.OH
Acetyl hydrate (acetic acid).
(C2H30)20
Acetyl oxide (acetic anhydride).
ACETIC ACID.
C2H402
C2H3O
II N
}
H
Acetamide.
Acetic acid is the acid of vinegar. It is the product of the
oxidation of alcohol. It is formed in a number of other reac-
tions, among which we may mention the oxidation of aldehyde,
ACETIC ACID.
493
the decomposition of methyl cyanide by potassium hydrate, the
action of carbon dioxide on sodium-methyl, and the dry distil-
lation of a great number of organic substances, such as wood,
starch, gum, sugar, etc.
Preparation. The large quantities of acetic acid employed
in the arts are obtained by the destructive distillation of wood.
The operation is conducted in large iron cylinders, heated
directly by a fire (Fig. 123). The products of the distillation

m
m
m
m
FIG. 123.
consist of liquids and gases. The liquids are condensed in a
large worm, tt, cooled by a continual circulation of cold water
through surrounding pipes mm; the gases are conducted back
to the fire-grate by the pipe h. The condensed product consists
of an aqueous portion and of tar. The greater part of the
latter is separated by a new distillation; the first portions
which pass contain wood-spirit, after which acetic acid distils.
The acid liquid is neutralized by lime, and the calcium ace-
tate formed is converted into sodium acetate by adding a solu-
tion of sodium sulphate. The liquid, separated by filtration
from the calcium sulphate, yields on evaporation sodium ace-
tate, still colored brown by tarry matters. The latter are
destroyed by frying the salt, that is, by heating it for some
time to 250°, a temperature which carbonizes the tar but does
not affect the sodium acetate. The mass is then exhausted
with water, the solution filtered, concentrated, and crystallized.
Crystals of pure sodium acetate are thus obtained, a salt which
was formerly called pyrolignite of soda. Acetic acid is pre-
42
494
ELEMENTS OF MODERN CHEMISTRY.
pared by drying this salt and distilling it with its weight of
concentrated sulphuric acid.
Or the dry salt may be decomposed by an exact quantity of
sulphuric acid. The acetic acid which separates from the
sodium sulphate may then be decanted, and cooled in a freez-
ing mixture. The portion remaining liquid is separated and
the solid mass constitutes pure acetic acid.
Vinegar. Vinegar is the product of the acid fermentation
of wine and other alcoholic liquids. The following process is
largely employed for the conversion of wine into vinegar. It
is the Orleans process. A small quantity of warm vinegar is
first introduced into large vats, which have already been used
for the operation and are impregnated with the peculiar fer-
ment formed; quantities of wine are then added at intervals
of several days, the vats being maintained at a temperature
between 24 and 27°. In a fortnight, the acetification is com-
plete, and a portion of the vinegar is withdrawn and replaced
by a new quantity of wine which also becomes converted into
vinegar. The process is thus continuous. Under these cir-
cumstances, the alcohol is converted into acetic acid by the
influence of a peculiar ferment that is called mother of vinegar.
t
shavings.
FIG. 124.
It is a vegetable product,
a mycoderm ( Mycoderma
aceti), which appears on
the surface of the liquid,
where it absorbs oxygen
from the air and subse-
quently cedes it to the
alcohol (Pasteur). Its
action may be compared
to that of platinum black.
By another process, a
mixture of weak alcohol,
water, and albuminoid
matter (the juice of pota-
toes, beets, etc.), contain-
ing the elements neces-
sary for the production of
the ferment, is allowed to
trickle over beech-wood

The latter, which have been previously steeped in
strong vinegar, are contained in a large cask, A (Fig. 124),
ACETATES.
495
ལ、།
where they rest upon a double bottom perforated with holes.
Tubes, tt, pass through the upper portion, maintaining a current
of air which enters at the lower portion of the cask. Under
these conditions, the liquid, which spreads over the shavings
and exposes a considerable surface to the air, becomes oxidized
with such energy that the temperature soon rises to 30°; a
second passage of the liquid through the casks completes the
acetification.
Properties of Acetic Acid.-Acetic acid is solid below 17°,
and crystallizes in large plates. It boils at 118°. Its density
at 0° is 1.0801. Its odor is pungent and acid. It is very.
corrosive. It mixes with water and alcohol in all proportions,
and when it is added to water there is a contraction in volume.
The maximum contraction, and consequently the maximum
density of aqueous acetic acid, corresponds to a mixture con-
taining C'H'O2 + H2O.
Vapor of acetic acid passed through an incandescent porce-
lain tube yields gases and deposits carbon, at the same time
forming small quantities of acetone, benzol, phenol, and naph-
thaline (Berthelot).
Phosphorus pentachloride converts acetic acid into acetyl
chloride, with formation of hydrochloric acid and phosphorus
oxychloride.
C2H3O.OH PC15
Acetic acid.
C2H3O.Cl + HCl + POCK³
Acetyl chloride.
If a mixture of small quantities of potassium acetate and
arsenious oxide be heated in a test-tube, dense white vapors
having an intense and disagreeable odor of garlic will be dis-
engaged.
This experiment permits the detection of minute traces of
acetic acid; if the latter exist in the free state in the liquid,
its potassium compound must first be formed. The white
vapor disengaged is due to a body formerly known as fuming
liquor of Cadet (see page 453).
ACETATES.
The more important neutral acetates have the composition
R'(C²H³O²) or "R" (C'H³O²)², according as the metal which
replaces the basic hydrogen of the acetic acid is univalent or
bivalent. There are many basic acetates.
Potassium Acetate, KC2H3O2.-This is prepared by satu-
496
ELEMENTS OF MODERN CHEMISTRY.
rating acetic acid with potassium carbonate and evaporating to
dryness. It is thus obtained in crystalline, very deliquescent
laminæ. It melts at 292°, and is very soluble in water.
Sodium Acetate, NaC H³O² + 3H20.—This salt is obtained
on a large scale in the arts in the manufacture of acetic acid.
It was formerly called pyrolignite of soda. It crystallizes in
large, oblique rhombic prisms, which are very soluble in water,
and effloresce in dry air.
Acetates of Lead.-Neutral lead acetate, Pb(C2H³O²)² +
3H 0, known also as sugar of lead, is made by neutralizing
acetic acid with litharge. It crystallizes in transparent, efflor-
escent, oblique rhombic prisms, having a sweet and astringent
taste. It dissolves in half its weight of cold water, and in 8
parts of alcohol. It melts in its water of crystallization at
75.5°.
The neutral solution of lead acetate dissolves oxide of lead,
forming different basic salts, according to the proportion of
oxide dissolved. The more important of these are a dibasic
acetate, Pb(C²H³O²)² + PыO + 4H2O, and a tribasic acetate,
Pb(C²H³O²)² + 2PbO + nH2O. These two salts are gener-
ally formed simultaneously when a solution of lead acetate is
boiled with litharge. The solution thus obtained is used in
medicine as Goulard's solution. If a few drops of it be added
to ordinary river or well water, a cloud is produced, owing to
the formation of lead sulphate and carbonate.
If carbonic acid gas be passed into a solution of the sub-
acetate of lead, a deposit of lead carbonate is formed. In this
reaction, which serves for the preparation of white lead by the
Clichy method, the excess of lead is removed from the subace-
tate by the carbonic acid, neutral acetate being formed and
remaining in solution.
Acetates of Copper.-The neutral acetate Cu(C'H³O²)² +
H'O, is prepared by double decomposition by mixing hot solu-
tions of sodium acetate and cupric sulphate. The cupric acetate
is deposited on cooling in beautiful, oblique rhombic prisms
of a deep bluish-green color. They dissolve in 5 times their
weight of boiling water. The dilute aqueous solution is de-
composed by boiling, a tribasic acetate being formed, while
acetic acid is set free.
When cupric acetate is heated, it first loses its water of crys-
tallization, and decomposes when the temperature reaches 240
or 250°, disengaging acetic acid, acetone, and carbon dioxide.
ETHYL ACETATE.
497
The residue is finely-divided copper. The product of the dis-
tillation is a blue liquid, which, when rectified, yields colorless
acetic acid mixed with a small quantity of acetone.
It was
formerly called radical vinegar.
The name verdigris is applied to a basic acetate of copper
consisting mostly of a dibasic acetate, Cu(C'H³O²)² + CuÔ +
CH2O. Verdigris is prepared by exposing to the air copper
sheets piled up in layers with the pulp of grapes. In a few
weeks the metal becomes covered with bluish crusts of verdi-
gris, which are scraped off and delivered to commerce in the
form of light-blue balls. The alcohol, formed by the fermenta-
tion of the sugar contained in the grape-pulp, becomes oxidized
by the air and is converted into acetic acid, and under the in-
fluence of the latter, the copper itself absorbs oxygen. Water
and copper basic acetate are thus formed.
Silver Acetate, AgC2H3O2.-This salt, which is but slightly
soluble in water, is precipitated when concentrated solutions
of sodium acetate and silver nitrate are mixed. It is deposited
from boiling water in brilliant, pearly, flexible plates, which
darken on exposure to light.
Ammonium Acetate, (NH)CHO-When acetic acid is
saturated by a current of ammonia gas, this salt is obtained as
a deliquescent, crystalline mass. It is very soluble in water
and in alcohol. When heated, it first loses ammonia, then
acetic acid, and acetamide finally distils.
NH+.C2H3O2
Ammonium acetate.
H2O + C²H³O.NH²
Acetamide.
It is used in medicine under the name spirit of Mindererus.
This is generally an impure solution of ammonium acetate,
charged with empyreumatic matters.
When distilled with phosphoric anhydride, ammonium ace-
tate yields methyl cyanide, or acetonitrile.
NH*.CH3O3 = C²H³N + 2H2O
ETHYL ACETATE.
C2H5.C2H3O2
This acetate, ordinarily known as acetic ether, is prepared
by distilling a mixture of alcohol, sulphuric acid, and potassium
or sodium acetate. The ethyl acetate passes over, together
with a certain quantity of alcohol which escapes the reaction.
42*
498
ELEMENTS OF MODERN CHEMISTRY.
It is purified by agitation with a solution of calcium chloride,
and the ether which floats is decanted, dried over calcium
chloride, and rectified on the water-bath.
It is a colorless liquid having a very agreeable, ethereal odor.
It boils at 77°. Density at 0°, 0.9105. It is but slightly
soluble in water, but dissolves in all proportions in alcohol and
ether. Like all compound ethers, it is readily decomposed by
potassium hydrate.
C²H³.C²H³O² + KOH
Ammonia converts it into acetamide and alcohol.
C³H³O.OC²H³ + NH³
KC²H³O² + C2H5.OH
C²H³.OH +、C²H³O.NH²
Ethyl acetate undergoes a remarkable reaction with sodium.
The metal dissolves in the ether, forming sodium ethylate and
the compound CH*NaO³.
3
5
2[C²H³O.OCH³] + Na² = NaO.C²H³ + CH³NaO³ + H²
The body CII NaO" is the sodium compound of acetyl-acetic
ether, CH¹ºO³ C²H²(C²H³O)O-OC'H³, which is derived
from acetic ether, C'H³O-OC"H³, by the substitution of an
acetyl group, CHO, for one atom of hydrogen in the radical
acetyl. The free acetyl-acetic ether may be obtained by the
action of hydrochloric acid upon the sodic compound C H³ÑaO³.
It is a colorless liquid having an agreeable odor, and boiling at
182°. Density at 5°, 1.03.
SUBSTITUTION PRODUCTS OF ACETIC ACID.
Three chlorinated acids are known which are derived from
acetic acid by substitution:
Monochloracetic acid
Dichloracetic acid
•
Trichloracetic acid
C2II3C102
C2112C1202
C21C1302
Monochloracetic acid is formed when a current of chlorine
is passed into acetic acid heated to 100°, and containing a small
quantity of iodine. As soon as chlorine begins to be disen-
gaged at the extremity of the apparatus, the operation is arrested
and the liquid distilled. That portion is collected which passes.
between 185 and 187°.
Monochloracetic acid is solid, and crystallizes in deliquescent,
rhomboidal tables or in prisms. It boils between 185 and 187.8°.
ACETIC ANHYDRIDE.
499
It is very corrosive. It is converted into glycollic acid when
heated with an excess of potassium hydrate.
KC'H CIO² + + KOH
Potassium
monochloracetate.
KC H (OH)O + KCl
Potassium glycollate.
Ammonia converts it into acetamic or amidacetic acid C2H2
(NH²)O.OH (glycocol) (Cahours).
CH CI
CO.OH
+ NH3
CH2.NH2
HCI +
CO.OH
Glycocol.
Monochloracetic acid.
Trichloracetic acid, C'HCPO, a very important compound.
in the history of the science, was discovered by Dumas in 1840.
It was then one of the most remarkable examples of a body
formed by substitution, and a comparison of its properties with
those of acetic acid led Dumas to announce the first idea of
chemical types.
It is obtained by exposing acetic acid to the action of a large
excess of chlorine in direct sunlight.
Trichloracetic acid is solid. It forms transparent and deli-
quescent, rhombohedral crystals, fusible at 52.3°, and boiling
between 195 and 200°.
Its aqueous solution regenerates acetic acid by the action of
sodium amalgam, an interesting reaction, since it furnished one
of the first examples of inverse substitution (Melsens), as the
replacement of chlorine by hydrogen is called. Water and
sodium amalgam constitute a slow source of hydrogen.
When boiled with potassium hydrate, trichloracetic acid fur-
nishes potassium carbonate and chloroform.
C'HCPO² = CHCP + CO²
ACETIC ANHYDRIDE.
(C2H30) 20
This important body, discovered by Gerhardt in 1852, is
prepared by the action of one part of phosphorus oxychloride
on three parts of dry sodium acetate. In this operation, acetyl
chloride is first formed, and this reacts upon an excess of so-
dium acetate, producing sodium chloride and acetyl acetate, or
acetic anhydride.
C²H³O.Cl +
Acetyl chloride.
C2H3O
Na} 0 =
Sodium acetate.
C2H3O
NaCl +
0
C2H3O
Acetic anhydride.
500
ELEMENTS OF MODERN CHEMISTRY.
Acetic anhydride is a colorless, mobile liquid, having a strong
odor of acetic acid. It boils at 138°. When thrown into
water, it first sinks to the bottom, and then, absorbing one mol-
ecule of water, is converted into acetic acid, which dissolves.
ALDEHYDE, OR HYDRIDE OF ACETYL.
C2H4O
This body was discovered by Döbereiner in 1821; its com-
position and principal properties were studied by Liebig.
Preparation.-Aldehyde is prepared by oxidizing alcohol by
heating it with manganese dioxide and dilute sulphuric acid,
or better, with potassium dichromate and sulphuric acid. The
vapors disengaged are condensed in a well-cooled receiver. The
distilled liquid is rectified over calcium chloride, only the more
volatile portion being collected. This is mixed with twice
its volume of ether, and the ethereal solution saturated with
ammonia gas. Crystals are deposited which constitute a com-
bination of aldehyde with ammonia, and the aldehyde is ob-
tained from them by adding a quantity of sulphuric acid exactly
sufficient to form ammonium sulphate with the ammonia; a
gentle heat is applied, and the aldehyde vapor is passed through
a tube filled with calcium chloride, and finally condensed in a
well-cooled receiver (Liebig).
Properties. Aldehyde is a colorless, very mobile liquid,
having a penetrating and somewhat suffocating odor. It boils
at 21°. It mixes in all proportions with water, alcohol, and
ether.
It combines with ammonia, forming aldehyde-ammonia, or
acetylide of ammonium (Liebig).
C2H4O.NH³
C2H3O.NH¹
It unites with the alkaline acid-sulphites, forming crystal-
lizable combinations.
It is very apt to become oxidized, being transformed into
acetic acid.
C²H¹O + 0 = C²H¹O²
If some aldehyde and a few drops of ammonia be added to
a solution of silver nitrate, and a gentle heat be applied, the
liquid soon becomes clouded, and the sides of the vessel con-
taining it are covered with a brilliant deposit of metallic silver.
ALDEHYDE.
501
By the action of sodium amalgam and water, aldehyde fixes
two atoms of hydrogen, and is converted into alcohol (A.
Wurtz).
C²H¹O + H² = C²H‘O
When hydrochloric gas is passed into a mixture of aldehyde
and absolute alcohol, monochlorether is formed.
C2H4O + C2H5.OH + HCI H20 +
C2H4CI
C2H5.
Monochlorether.
Chlorine converts aldehyde into acetyl chloride and other
products (A. Wurtz).
C²H³O.H + CI²
C²H³O.C) + HCl
When treated with phosphorus pentachloride, aldehyde ex-
changes its atom of oxygen for two atoms of chlorine, and is
transformed into monochlorethyl chloride, CH4Cl² (ethylidene
chloride).
CH3
сно
+ PC15
CH3
CHCI2
+ РОСІЗ
Aldehyde.
Ethylidene chloride.
Aldehyde has a great tendency to become converted into
polymeric modifications. Among these are paraldehyde, which
is liquid, and metaldehyde, which is solid (Liebig).
Dry hydrochloric acid gas converts aldehyde into ethylidene
oxychloride (an isomeride of dichlorether), eliminating water.
CH®CFO + H2O
Ethylidene oxychloride.
2C²H¹O + 2HCl
By the action of hydrochloric acid diluted with twice its
volume of water, aldehyde doubles its molecule and is converted
into a thick, colorless, neutral body, boiling at 95° in a vacuum;
it is soluble in water and reduces ammoniacal silver nitrate.
This body is aldol, C'HO² (A. Wurtz).
When heated with ordinary hydrochloric acid, aldehyde gives
crotonic aldehyde (Kekulé).
2C2H+O
Aldehyde.
H²O + C¹H®O
Crotonic aldehyde.
The same transformation takes place when aldehyde is heated
to 100° with a small quantity of zinc chloride and a trace of
water.
502
ELEMENTS OF MODERN CHEMISTRY.
ACETYL CHLORIDE.
C2H3O.CI
CH3
Coci
This body was obtained by Gerhardt in 1852, by treating
sodium acetate with pentachloride, or oxychloride of phos-
phorus.
NaC2H3O2 + PC15
Sodium acetate.
C2H³OCI+NaCl + POCI³
Acetyl chloride.
Phosphorus oxychloride.
It is also formed by the action of chlorine on aldehyde.
It is a colorless, mobile liquid, having a pungent odor. It
boils at 55°.
If it be poured into water, it sinks to the bottom, but rapidly
decomposes into hydrochloric and acetic acids.
C²H³O.Cl + H2O HCl + C²H³0.0H
It undergoes a similar decomposition with alcohol, forming
ethyl acetate and hydrochloric acid.
C²H³O.CI + C²H³.OH HCI + C²H³.C²H³O².
With ammonia, it forms acetamide and ammonium chloride.
C²H³O.Cl + 2NH³ NH¹Cl + C²H³O.NH²
It reacts with acetates, forming acetic anhydride.
TRICHLORACETYL HYDRIDE, OR TRICHLORAL-
DEHYDE.
(CHLORAL.)
C2C13HO
CC13
CHO
This important body was discovered by Liebig and Dumas.
It is formed by the prolonged action of chlorine on alcohol.
It is a colorless, mobile liquid, having a peculiar, penetrating
odor. It boils at 94.4° (Dumas).
Gerhardt regarded it as aldehyde in which the three atoms
of hydrogen of the radical are replaced by three atoms of
chlorine.
C2H3O.H
Aldehyde.
(Acetyl hydride.)
C2C1³O.H
Chloral.
(Trichloracetyl hydride.)
Its reactions resemble those of aldehyde. It forms crystal-
lizable compounds with the disulphites. Its ammoniacal solu-
ACETONE.
503
*
tion reduces silver nitrate. These facts seem to indicate that
chloral contains the group CHO, which is characteristic of the
aldehydes; its constitution is then expressed by the formula
CC13
сно
It regenerates aldehyde by the action of nascent hydrogen
(Personne).
The alkaline hydrates decompose it into chloroform and a
formate (Dumas).
CHCFO + KOH
Chloral.
KCHO² + CHCP³.
Potassium formate.
Nitric acid converts it into trichloracetic acid, in the same
manner that aldehyde is converted into acetic acid.
+ H2O =
CC13
C²HCP³O + O C2HCPO²
CH(OH)2
Chloral forms a crystallizable compound with water, C'HC¹³O
› called chloral hydrate. The latter
melts åt 57°, and boils at 98° (Personne), being at the same
time decomposed into anhydrous chloral and water. It is very
soluble in water.
In contact with concentrated sulphuric acid, chloral is
rapidly converted into a white, solid substance which is insol-
uble in water; it has the same composition as ordinary chloral,
and is called insoluble chloral.
Chloral also combines with alcohol, forming alcoholate of
chloral (Personne).
Chloral hydrate has for some time been successfully employed
in medicine as an anodyne and hypnotic.
ACETONE.
C3H60
Acetone is the methylide of acetyl, C'H³O.CH³, and since
acetyl itself is carbonyl (carbon monoxide) methylide, CH³-CO,
acetone can be regarded as carbonyl dimethylide, CH³-CO-CH³.
co" {C
CI
Carbonyl chloride.
S CH3
CO"
CH3
{
Carbonyl dimethylide (acetone).
Indeed, the synthesis of acetone has been made both by treat-
504
ELEMENTS OF MODERN CHEMISTRY.
ing acetyl chloride with zinc methyl (Pebal and Freund), and
by treating sodium methyl with chlorocarbonic gas (carbonyl
chloride).
Zn(CH3)2+2(C²H³O.CI)
Zinc methyl.
=
Acetyl chloride.
Cl
Cl
2(CH³.Na) + CO {
Sodium methyl. Carbonyl chloride.
2(C²H³O.CH³) + ZnCl2
Acetone.
CH3
2NaCl + COCH³
Acetone.
3
Preparation.-Acetone is prepared by distilling dry calcium
acetate in a clay retort. The vapors given off are condensed
in a well-cooled receiver, and the liquid obtained is distilled on
a water-bath with an excess of calcium chloride.
Ca(C2H3O2) CHO+ CaCO³
=
Properties.-Acetone is a colorless liquid, having a slightly
empyreumatic, ethereal odor. It boils at 56°. It dissolves in
all proportions in water, alcohol, ether, and wood-spirit.
Like aldehyde, it forms crystallizable combinations with the
alkaline acid-sulphites.
In presence of nascent hydrogen, produced by sodium amal-
gam and water, it fixes H2 and is converted into isopropyl
alcohol (Friedel).
CH³
CH3
CO + H2
I
CH.OH
CH3
Isopropyl alcohol,
CH3
Acetone.
It is seen by this method of formation that isopropyl alcohol
contains a group CHOH, united to two methyl groups; it is a
secondary alcohol (page 473).
Isopropyl alcohol is not the only product of the action of
nascent hydrogen on acetone. The reaction gives rise to a
product of condensation resulting from the addition of H² to
two molecules of acetone. This has received the name pina-
cone.
2C³H®O + H²
C6H1402
Pinacone.
It is a tertiary glycol (see page 522). It constitutes a color-
less, crystallizable mass, fusible between 35 and 38°, and boil-
ing at 171-172°. By the action of dilute and hot sulphuric
or hydrochloric acid, it loses one molecule of water and is con-
ACETAMIDE.
505
verted into a neutral liquid, boiling at 106°. This is pinaco-
lin, CH¹²O.
When acetone is added in small portions to phosphorus
pentachloride, a very energetic reaction takes place and two
chlorides are formed. One of them, CH C12 (methylchlor-
acetol), boils at 70°. The other, C³H5Cl (monochloropropy-
lene), boils at 23° (Friedel).
C3H6O + PC15
CHCl
CHCI POCI³
C'H CHCI
Hot, concentrated sulphuric acid removes the elements of
water from acetone and converts it into a hydrocarbon, which
has received the name mesitylene (Kane).
3C³H60 — 3H²O C9H12
Acetone.
ACETAMIDE.
C2H3O.NH2
Mesitylene.
This amide may be obtained by heating ethyl acetate to 100°
in sealed tubes with aqueous ammonia. Alcohol and acetamide
are formed according to the equation
C²H³.C²H³O + NH³ C²H³O.NH² + C²H³.OH
When the resulting liquid is evaporated in a vacuum, the
acetamide remains. It may be purified by distillation, collecting
that which passes above 200°.
Acetamide is also formed by the action of ammonia on acetyl
chloride; one of the readiest methods of preparing it consists
in simply distilling ammonium acetate.
It is a solid, crystallizable body, soluble in water in all pro-
portions. Its odor resembles that of mice. Boiling potassium
hydrate reacts with it, forming potassium acetate and ammonia.
Phosphoric anhydride removes from it the elements of water,
converting it into acetonitrile or methyl cyanide.
C'H³O.NH2 C²H³N + H2O
ACIDS OF THE SERIES CnH2O2
Formic and acetic acids, of which the principal compounds
have just been described, are the first terms of a very extensive
homologous series. It is the series of volatile fatty acids, so
named because it includes a great number of compounds which
W
43
506
ELEMENTS OF MODERN CHEMISTRY.
*
were at first obtained from the natural fatty bodies, and which
are the fatty acids proper. Among the bodies congeneric with
acetic acid, those of which the molecules are less complicated
are liquid at ordinary temperatures; the others are solid. The
following table gives the nomenclature, composition, and prin-
cipal physical properties of these acids:
NAMES OF ACIDS.
Formic acid
CRUDE
RATIONAL
MELTING- BOILING-
FORMULE.
FORMULÆ.
POINTS.
POINTS.
CH202
H-CO.OH
1°
99°
Acetic acid
·
C²11+02
CH³-CO.OH
17°
118°
Propionic acid
C3H6O2
C2115-CO.OH
-21°
140.7°
Butyric acid
C+H8O2
C3H7-CO.OII
0°
163°
Valeric acid (isovaleric)
C5111002
C+Hº_CO.OH
175°
Caproic acid (isocaproic)
C6H12(2
C5H-CO.OH
5°
199.7°
Enanthylic acid
•
C7H1402
C6II13-CO.OH
212°
Caprylic acid
C8111602
C71115-CO.OH
14°
236°
Pelargonic acid
C9H1802
C8H17-CO.OH
18°(?) 260°
Capric acid.
Lauric acid.
Myristic acid
Palmitic acid
Margaric acid
Stearic acid.
Arachnic acid
C10H 2002
C9H19-CO.OH
27.2°
C12112402
(11H23-CO.OH
43.6°
•
•
('1411280)2
C131127-CO.OII
53.8°
CIGH3202
•
C151131-CO.OII 62°
C17H3402
•
C16H33-CO.OH 60°
C18113602
C171135-CO.011
69.2°
C'20114002
C19H39-CO.OII 75°
Benic acid
C22H4102
C21H43-CO.OI 96°
Cerotic acid
•
('27][5402
C26H53-CO.OH
78°
Melissic acid
C30116002
C291159-CO.01
SS°
We have already noticed the existence of numerous isomeric
alcohols, and in their study the principles of isomerism have
been explained. Such isomerides exist also in the series of
acids, and are caused by the different atomic structure of the
radicals, CnH2n+1, which figure in the preceding formula. We
will consider two examples. 1. When normal butyl alcohol,
CH³-CH2-CH²-CH2.OH, is oxidized, normal butyric acid, or
the butyric acid of fermentation, is obtained, CH³-CH2-CH²–
CO.OH. The acid obtained by oxidation of the butyl alcohol
of fermentation is different from this, and the difference is
caused by the difference in structure of the radicals (C³H')'.
Isobutyric acid, derived from the alcohol of fermentation,
CH³
whose constitution is >CH-CH2.OH, contains
CH³
CH-CO.OH.
CH³
CH3
The acid is derived from the alcohol by the substitution of
O for H² in the group (CH2.OH)'.
2. As we have already seen, the constitution of amyl alcohol
of fermentation is expressed by the formula
PROPIONIC ACID.
507
CH³>CH-CH2-CH².OH.
3
CH³
The valeric acid produced by its oxidation is then
CH>CH-CH_COOH
CH3
But normal valeric acid is also known, and contains
CH³-CH2-CH2-CH2-CO.OH
It results from the oxidation of normal amyl alcohol
CH³-CH2-CH2-CH2-CH².OH
Another interesting isomeride of valeric acid is trimethyl-
acetic acid, which was discovered by Boutlerow.
If we compare the three isomeric acids, C³H¹O², with acetic
acid itself, we will find that their isomeric relations can be ex-
pressed in a very simple manner, by saying that normal valeric
acid is propylacetic acid, the acid derived from the alcohol of
fermentation is isopropylacetic acid, and lastly, that Boutlerow's
acid is trimethylacetic acid.
CH3
CH2(C3H7)
CII3
CHI³
CO.I
Acetic acid.
со он
Propylacetic acid.
CO.OH
CH²(CH<
он
Isopropylacetic acid. Trimethylacetic acid.
C(CH3)3
со.он
We cannot dwell further on the subject; that which pre-
cedes is sufficient to elucidate the isomerism of acids of the
series CnH2O)².
Propionic Acid, C3H6O2.-This acid is formed by the action
of potassium hydrate on ethyl cyanide. It is also a product of
fermentation; thus, it has been obtained by allowing a solution
of sugar, mixed with chalk and cheese, to ferment during a
year. It is also formed in small quantity in the distillation of
wood.
Wanklyn made its synthesis by passing carbon dioxide over
sodium ethyl.
CO.O + C²H³Na
C²H³-CO.ONa
Sodium propionate.
Propionic acid may also be formed, though with difficulty,
by the direct combination of carbon monoxide and ethylate of
sodium.
CO + C²H³.ONa
C2H³-CO.ONa
508
ELEMENTS OF MODERN CHEMISTRY.
Properties. It is a colorless, mobile liquid, having an odor
like that of acetic acid. It solidifies at -21°, and boils at
140.7°. Density at 21°, 0.996. It is miscible with water in
all proportions. Calcium chloride separates it from its aqueous
solution.
There are a great number of substitution products directly
related to propionic acid. Among these are the chlorine, bro-
mine, and iodine derivatives, and the amides. Two of these
derivatives are known of each particular species, presenting
curious isomeric relations. The following examples will serve
as illustrations:
CH3
CH3
CH2CI
CH3
CH2
CHCI
сна
созн
CO2H
CO₂H
CH(NH2)
CO2H
1
Propionic
a-Chloropro-
B-Chloropro-
acid.
pionic acid.
pionic acid.
a-Amidopropi-
onic acid.
CH2(NH2)
сиг
CO2H
B-Amidopropi-
onic acid.
Only the iodo-derivatives will be described here, and farther
on we will mention the amides.
a-iodopropionic acid, C³H'IO', is prepared by the action of
concentrated hydriodic acid or phosphorus iodide on lactic
acid.
C³H6O³ + HI = C³H³IO² + H²O
Lactic acid.
It is a thick, oily body, almost insoluble in water.
B-iodopropionic acid is formed by the action of concentrated
hydriodic acid or phosphorus iodide and water on glyceric
acid.
C³H 03HI CHIO² + 2H2O +1²
Glyceric acid.
It is also formed by the direct combination of hydriodic acid
and acrylic acid, CH'O".
It is a solid, occurring in crystalline laminæ, fusible at 82°.
It is very soluble in boiling water. When heated to 180°
with hydriodic acid, it is converted into propionic acid.
C³H³IO² + HI = I² + C³H®O²
Normal Butyric Acid, CHO².-This acid was discovered
by Chevreul in butter, where it exists in combination with
glycerin in butyrin. Pelouze and Gélis have shown that it
is formed in abundance when a solution of sugar, glucose, or
even starch is abandoned for several weeks with the addition
BUTYRIC ACIDS.
509
of chalk and old cheese. In about ten days a mass of calcium
lactate is formed, but this soon disappears, gases being at the
same time disengaged. The mass again becomes liquid, and
the solution contains calcium butyrate. This is converted into
sodium butyrate, which is finally decomposed by sulphuric
acid; the butyric acid separates in the form of an oily liquid,
which is decanted and distilled.
Properties. Butyric acid is a colorless liquid, having a
pungent and disagreeable odor which recalls that of rancid
butter. It is quite soluble in water. Density at 14°, 0.958.
Boiling-point, 163°.
2
It perfectly neutralizes the bases, forming butyrates. These
salts, which are mostly soluble in water, have a fatty aspect.
Calcium butyrate, Ca(C'H'O²), is more soluble in cold water
than in hot water, so that its cold saturated solution becomes
a solid mass when heated to 70°.
Butyrone. When calcium butyrate is subjected to dry dis-
tillation, it yields, as principal product, butyrone, one of the
homologues of acetone (Chancel).
Ca(C¹H7O²)²
2
Calcium butyrate.
C'H¹¹O + CaCO³
Butyrone.
Butyrone is a colorless liquid, lighter than water, and having
a peculiar, ethereal odor. It boils at 144°.
Butyral. The principal product of the distillation of a mix-
ture of butyrate and formate of calcium is butyral, or butyric
aldehyde, C¹H³O.
Ca(C*HO*)? + Ca(CHO)?
2CaCO³ + 2C¹H®O
This important reaction, discovered by Piria, permits of the
conversion of butyric acid into its aldehyde; it can also be ap-
plied to the transformation of other acids into aldehydes.
Butyral, which was discovered by Chancel, is a liquid, boil-
ing at about 70°. Like aldehyde, it forms a crystallizable
compound with ammonia, and it unites with the alkaline acid-
sulphites as do the other aldehydes and the acetones.
İsobutyric Acid.-An acid isomeric with butyric acid is
known, and is designated as isobutyric acid (Morkownikof).
It is formed by the oxidation of butyl alcohol of fermenta-
tion, and exists naturally in the fruit of the Ceratonia siliqua
(carob locust, St. John's bread). It is also obtained by decom-
posing isopropyl cyanide with potassium hydrate.
(C³H¹)'CN + 2H2O = NH³ + (C³H¹)'-CO²H
43*
510
ELEMENTS OF MODERN CHEMISTRY.
It is a liquid having a disagreeable odor, like that of the
acid of fermentation. Density at 20°, 0.9503. It boils at
154°.
Valeric Acid, CH¹ºO². This acid was discovered by Chev-
reul, who first obtained it from dolphin oil (phocenic acid.) It
may be prepared by distillation of valerian root with water;
hence its name. It exists also in the root of angelica, in the
Athamanta oreoselinum and in the fruit and bark of the Vibur-
num opulus. The same acid is formed when amyl alcohol is
oxidized by a mixture of potassium dichromate and sulphuric
acid.
CH¹²0 +0² · H2O + CH¹00²
It is also formed when potassium hydrate is boiled with iso-
butyl cyanide, by a reaction similar to that which has already
been indicated for the formation of isobutyric acid.
Valeric acid is a colorless liquid, having a pungent, disagree-
able odor. Density at 0°, 0.947. It boils at 175°. It dissolves
in 30 parts of water, from which it is precipitated by the addi-
tion of neutral salts. Its ammonium salt is used in medicine.
Normal valeric acid, which has already been mentioned (page
507), is a colorless liquid, smelling like butyric acid. It boils
at 184-185°, and its density at 0° is 0.9577.
Trimethylacetic acid is formed when potassium hydrate is
boiled with the cyanide derived from trimethylcarbinol.
(CH3)3C-CN + 2H2O = (CH³)³C-CO.OH + NH³
It is a crystalline mass, fusible at 35°, and boiling at 163.8°.
It dissolves in 40 parts of water at 20°.
Caproic Acids. There are several isomeric acids having the
composition C6H12O². One of them was discovered in butter
by Chevreul. Normal caproic acid is formed by the oxidation
of normal hexyl alcohol, and in the decomposition of normal
amyl cyanide by boiling potassium hydrate. It is an oily liquid,
having but a faint odor; its density at 0° is 0.945, and it boils
at 205°. Leucine, CH1NO, an important nitrogenized body
which exists in the animal economy, is an amide, CH¹(NH²)O²,
of normal caproic acid.
The caproic acid mentioned on page 506 is an isomeride of
the preceding acid. It is obtained by decomposing, by potas-
sium hydrate, amyl cyanide derived from the alcohol of fer-
mentation.
FATTY ACIDS.
511
Our limited space will not permit of a description of all of
the acids of this series; we can only briefly consider the last
members.
Palmitic Acid, C6H2O2.-This exists in palm-oil in com-
bination with glycerin. It is prepared on a large scale in
England by distilling palm-oil by means of superheated steam,
which decomposes the oil into fatty acid and glycerin. The
fatty acids solidify on cooling. The mass is expressed to re-
move the liquid oleic acid with which it is impregnated, and so
obtained in dry, white cakes, which are used for the manufac-
ture of candles.
Margaric Acid, CH3O.-According to Chevreul, this acid
exists in all solid fats. To separate it from stearic acid, which
always accompanies it, Chevreul recommends the following
process: olive-oil is saponified with litharge and water, and the
lead-plaster or soap thus obtained is allowed to cool; after
separating it from the water which holds the glycerin in solu-
tion, it is pulverized and exhausted with ether, which dissolves
the lead oleate and leaves the margarate. The two salts being
composed by hydrochloric acid, furnish respectively oleic and
margaric acids.
Margaric acid crystallizes in white scales, fusible at 60°.
Heintz considers that the margaric acid obtained from many
fats is a mixture of palmitic and stearic acids.
36
Stearic Acid, CHO", was obtained from tallow by Chev-
reul. It is a solid, melting at 69.2°. After cooling, the fused
acid becomes a laminated, white mass. It is insoluble in
water, but dissolves in alcohol and ether. The alcoholic solu-
tion deposits it in small pearly scales, which are not greasy to
the touch. Stearic acid is used for the manufacture of stearin
candles.
The alkaline stearates are soluble in water. If a large excess
of water be added to the solution of a neutral stearate, à crystal-
line precipitate is formed which, according to Chevreul, is an
acid stearate. On this reaction he has founded a method for
the preparation of stearic acid.
The stearates of calcium, barium, and lead are insoluble in
water, and can be obtained by double decomposition.
Cerotic and Melissic Acids. These acids have been ob-
tained from wax by Brodie (page 480).
512
ELEMENTS OF MODERN CHEMISTRY.
OLEIC ACID AND ITS HOMOLOGUES.
34
2n-2
Oleic acid, which has just been mentioned and which Chev-
reul obtained from olein, is the principal constituent of a great
number of oils and fats; it does not belong to the series of
volatile fatty acids. Its formula, C18H30°, shows that it differs
from stearic acid by containing two atoms of hydrogen less
than the latter acid. It belongs to the series CH²n-²Ò².
Pure oleic acid is an oily liquid which solidified to a crys-
talline mass at 4°. Its alcoholic solution deposits it, when
cooled, in small needles, fusible at 14°. The peroxide of nitro-
gen converts oleic acid into a solid, crystallizable, isomeric modi-
fication of the same acid, named by Brodie elaidic acid.
Acrylic Acid, CHO².-This is the first term of the series
CnH2n-20². It receives its name from the fact that it results
from the oxidation of acrolein, or acrylic aldehyde, CHO,
which is formed in the destructive distillation of neutral fatty
substances and glycerin and its compounds; it is a product of
the dehydration of glycerin.
C3H8O3
Glycerin.
C³H¹O + 2H2O
Acrolein.
Acrolein reduces silver oxide, like the other aldehydes,
being converted into acrylic acid. This acid is liquid, and boils
above 100°. Nascent hydrogen converts it into propionic acid.
C³H¹O² + H2 C3H6O2
Crotonic Aldehyde and Acid.-These two bodies are homo-
logues of acrylic aldehyde and acid.
C3H40 acrylic aldehyde.
C4H6O crotonic aldehyde.
C3I1402 acrylic acid.
CII602 crotonic acid.
Crotonic aldehyde is one of the numerous transformation
products of ordinary aldehyde. When the latter body is sub-
jected to the action of certain salts, it loses the elements of
water and is converted into a body which Lieben called acral-
dehyde, but which is no other than crotonic aldehyde.
2C2H¹O C¹HO + H2O
This aldehyde is a liquid having a very irritating odor and
an acrid taste. It boils at 103°.
When submitted to the action of oxidizing agents, such as
POLYATOMIC COMPOUNDS-ETHYLENE.
513
silver oxide in presence of water, it is converted into crotonic
acid.
C‘H®O + 0 = C¹H®O²
Three isomeric modifications of this acid are known. One
is liquid, the others are solid.
POLYATOMIC COMPOUNDS.
After the description of the comparatively simple compounds
which are naturally grouped with the monatomic alcohols, we
proceed to the more complex compounds constituting the poly-
atomic alcohols and their derivatives. The latter alcohols are
neutral hydrates, capable of reacting with the acids to form neu-
tral combinations analogous to the compound ethers. Those
better known are related to the saturated hydrocarbons, from
which they are derived by the substitution of several hydroxyl
groups for as many atoms of hydrogen.
C2H6
Ethane.
C2H4(OH)2
Ethylene dihydrate
(glycol).
C3H8
Propane.
C3H5(OH)3
Glyceryl tri-
hydrate (glycerin).
C6H14
CHII10
Butane.
Hexane.
C+H(OH)+
C6HS(OH)6
Erythrite.
Munnite.
By oxidation of these polyatomic alcohols, polyatomic acids
are produced which bear the same relation to the former that
acetic acid bears to ordinary alcohol.
It will be noticed that the radicals of these alcohols are un-
saturated hydrocarbons, that is, they contain less hydrogen than
the saturated hydrocarbons, CnH2n+2. Of these radicals, only
those can exist in a free state which contain an even number
of atoms of hydrogen. We will briefly consider the more
important of them.
ETHYLENE.
C²H¹ = CH2=CH²
This gas, formerly known as olefiant gas or heavy carbu-
retted hydrogen, is formed in a great number of reactions. It
is produced, together with other hydrocarbons, when substances
rich in carbon and hydrogen, such as fats and resins, are de-
composed by dry distillation, that is, by the destructive action
of heat.
W**
514
ELEMENTS OF MODERN CHEMISTRY.
Preparation. It is obtained in the laboratory by dehydrat-
ing alcohol by a large excess of sulphuric acid. Ordinarily, a
mixture of one part of alcohol and 4 parts of concentrated sul-
phuric acid is heated in a flask containing almost enough sand
to absorb the entire liquid. The gas disengaged is passed
through a wash-bottle containing potassium hydrate, and may
then be collected over water.
Towards the close of the operation the liquid blackens, and
much sulphurous and carbonic acid gases are disengaged.
These are absorbed by the potassa in the wash-bottle.
The following equation expresses the reaction by which
ethylene is formed:
C2H6O C²H¹ + H2O
Composition and Properties.-Ethylene is a colorless gas,
having a feeble, ethereal odor. Its density is 0.9784 compared
to air, or 14 compared to hydrogen.
Its composition may be deduced from the following experi-
ment:
2 volumes of ethylene (2 cubic centimetres, for example)
and 6 volumes of oxygen are introduced into an cudiometer
over mercury. After the passage of the spark, the 8 volumes
will be found to be reduced to 4 volumes, all of which will be
entirely absorbed if a solution of potassium hydrate be passed
into the tube. The 4 volumes are therefore carbon dioxide.
4 volumes of carbon dioxide represent 2C02.
2 volumes of ethylene therefore contain C².
4 volumes of carbon dioxide contain but 4 of the 6 volumes of oxygen
employed; the other two have therefore been used in the formation of
water and have burned 4 volumes of hydrogen.
2 volumes of ethylene then contain 4 volumes of hydrogen.
Eudiometric analysis therefore indicates the composition of
ethylene to be
C2H + 2 volumes.
This gas is inflammable and burns in the air with a brill-
iant flame. When mixed with three volumes of oxygen and
ignited, it produces a violent explosion.
It is slowly absorbed by concentrated sulphuric acid, ethyl-
sulphuric acid being formed. When ethylene is heated with
hydriodic acid, the two bodies combine directly to form ethyl
iodide.
If one volume of ethylene and two volumes of chlorine be
ETHYLENE.
515
rapidly mixed in a tall jar, and a lighted match be applied, the
mixture takes fire and burns with a red flame extending to the
bottom of the jar, which becomes covered with a black deposit
of carbon.
C²II+ + 201²
4HCl + C²
If equal volumes of ethylene and chlorine be mixed and ex-
posed to diffused light on the pneumatic trough, the water will
soon rise in the jar, and the two gases will disappear. At the
same time, oily drops will appear on the sides of the jar and
upon the surface of the liquid. The body so formed is a liquid
insoluble in water, and results from the direct combination of
ethylene and chlorine. It was formerly called Dutch liquid,
or Dutch oil (hence the old name olefiant gas); it is now called
ethylene chloride. Its composition is expressed by the formula
C2H+Cl². It boils at 82.5°.
If a small quantity of bromine be poured into a large flask
filled with ethylene, and manipulated so that the bromine may
form a thin layer on the sides of the flask, an elevation of tem-
perature will be observed, and the liquid will rapidly become
colorless. The bromine has combined with the ethylene to
form a colorless liquid, ethylene bromide, boiling at 131°.
Ethylene iodide, CH'I', may be obtained by introducing
iodine into large jars filled with ethylene, and exposing to dif
fused light during several days. The iodine is little by little.
converted into a solid, white body, which may be purified by
crystallization in alcohol; it is ethylene iodide.
Chloro-Derivatives of Ethylene and Ethylene Chloride.-
If ethylene chloride be heated with an alcoholic solution of
potassium hydrate, a brisk reaction soon takes place. A gas
is disengaged and may be collected over water; on contact
with a lighted taper, it burns with a flame tinged with green.
This gas is chlorethylene. It is formed according to the fol-
lowing equation:
C²H¹CI² + KOH
H2O + KCl + C²H³Cl
Like ethylene itself, chlorethylene will combine directly with
two atoms of chlorine, forming chlorethylene chloride, CH³Cl.
Cl², which may also be obtained by the action of chlorine on
ethylene chloride.
Chlorethylene chloride is decomposed by alcoholic potassa,
like ethylene chloride. Water, potassium chloride, and dichlor-
ethylene are formed.
516
ELEMENTS OF MODERN CHEMISTRY.
C2H3C13+ KOH = H2O + KCl + C²H²C¹²
Chlorethylene chloride.
Dichlorethylene.
In its turn, dichlorethylene can fix two atoms of chlorine,
forming dichlorethylene chloride.
These reactions have permitted the preparation of two
classes of chloro-compounds,-one derived from ethylene chlo-
ride, the other from ethylene itself.
DENSITIES.
BOILING-POINTS.
C2H4C13 ethylene chloride.
1.256 at 12°
82.5°
C2H3C13 chlorethylene chloride.
1.422 at 17°
115°
C2H2C14 dichlorethylene chloride.
1.576 at 19°
1370
C2C16
C2HC15 trichlorethylene chloride.
carbon sesquichloride.
158°
182°
C2H4
C2H3C
ethylene.
chlorethylene.
C2H2C12 dichlorethylene.
C2HC13 trichlorethylene.
C2C1+ tetrachlorethylenc.
-18 to -15°
1.250 at 14°
35 to 40°
2.619 at 20°
87 to 88°
116.7°
Regnault, who carefully studied these bodies, has shown
that the terms of the first series are isomeric with the chloro-
derivatives of ethyl chloride, with the exception of the last
two, which are the same in both series.
That we may more thoroughly understand this isomerism,
we will consider ethylene chloride, C'H C12, and its isomeride
dichlorethane, called also ethylidene chloride. In the first,
two atoms of chlorine are united, each to a different atom of
carbon; in the second, both are united to the same carbon
atom.
CH2C1
CHECI
Ethylene chloride.
CHC12
CHI³
Ethylidene chloride.
Tetrachlorethylene was discovered by Faraday in 1821. It
is formed by the action of alcoholic potassium hydrate on tri-
chlorethylene chloride.
C2HC15
C2C1¹ + HCl
It is also formed by the action of a red heat on carbon
sesquichloride.
C¹²C16
C²CI¹ + C¹²
It is a very mobile liquid, which does not solidify at -18°.
It absorbs chlorine under the influence of direct sunlight, being
transformed into carbon sesquichloride, CC.
HOMOLOGOUS SERIES, CH².
517
HOMOLOGOUS SERIES, CnH2n
Ethylene is the first member of a rich series of homologues,
of which we will summarily describe a few of the others. It
is, however, important to remark that since ethylene is (CH²)²,
it would seem that the constitution of the superior hydrocar-
bons of the series should be expressed by the formula (CH2)".
Thus far none of these normal hydrocarbons have been isolated.
For example, normal propylene, CH2-CH2-CH2, is unknown.
The compound CH, which will shortly be described, is an
isomeride of normal propylene, and its constitution is expressed
by the formula CH³-CH=CH². It absorbs chlorine directly,
forming the chloride.
CH3-CHCI-CH²CI
Above the fourth member of this series, butylene, the
number of isomerides increases rapidly. Thus, the butylene
derived by dehydration from butyl alcohol of fermentation is
CH3
CH3
C=CII²
It is formed according to the following reaction:
CH3.
CII³
CH-CH2.OH H20
←
CH3
CH³
C=CH2
Independently of this butylene, there are two others, the
formation and principal properties of which will be indicated
farther on.
Their constitutions are expressed by the formulæ
CH3-CH=CH-CH3
CH3-CH2-CH=CH²
The isomeric relations of these three butylenes may be repre-
sented in a very simple manner if we consider them to be
derived from ethylene, HC-CH', the hydrogen of which is
partly replaced by methyl or ethyl. The following compounds
are thus obtained:
Dimethylethylene a
Dimethylethylene ẞ (normal)
Ethylethylene
(CH3)2C=CH2, boils at -6°.
(CH³) HC=CH(CH3), boils at +3°.
(C²H³)HC=CH2, boils at —5°.
10
The fifth member of the series, amylene or pentene, CH¹º,
presents still more numerous isomerides, but they can all be
explained by the principles already exposed: they may be re-
44
518
ELEMENTS OF MODERN CHEMISTRY.
garded as derivatives of ethylene by the substitution of a pro-
pylic or isopropylic group for one atom of hydrogen, or by the
substitution of an ethyl group and a methyl group for two
atoms of hydrogen, or lastly, by the substitution of three methyl
groups for three atoms of hydrogen.
Propylene, C³Hº.—To prepare this gas in a pure state Ber-
thelot and de Luca heat allyl iodide with mercury and concen-
trated hydrochloric acid.
6
2C³H³I + 4Hg + 2HCl =H2Cl2 + HgI² + 2CH
Propylene is a colorless gas, having a feeble, alliaceous odor.
It is rapidly absorbed by sulphuric acid, with formation of
isopropylsulphuric acid (Berthelot).
C3H6 + H2SO4
(C³ H7)'>SO±
H
It unites directly with hydriodic acid, forming an iodide
which is isomeric with propyl iodide.
C³H+HI (C³H')'I
Propylene unites directly with chlorine and bromine, forming
propylene chloride, CHCl², and propylene bromide, CHºBr².
The latter is a colorless liquid, boiling at 145°.
The propylene just described is not normal propylene, (CH²)³.
Its constitution and that of its bromide are expressed by the
formulæ
CH3-CH=CH2
Propylene.
CH3-CHBr_CHBr
Propylene bromide.
Normal propylene is not known, but the corresponding bro-
mide exists. It has been obtained by heating allyl bromide,
C³H'Br, with hydrobromic acid.
CH2=CH-CH²Br + HBr
Allyl bromide.
CH2Br-CH2-CH2Br
Normal propylene bromide.
The latter bromide is a colorless liquid, boiling at 165°.
BUTYLENES, C4H8.
1. Dimethylethylene a, (CH3)2C-CH2.- This body is
formed when isobutyl alcohol is dehydrated by zinc chloride,
or by the action of alcoholic potassium hydrate on butyl iodide,
CHI. It boils at -6°. It unites directly with hydriodic acid,
forming tertiary butyl iodide, (CH³)'CI-CH³, and combines
AMYLENES.
519
with bromine, forming the bromide (CH3)2CBr-CH Br, which
boils at 149°.
2. Dimethylethylene ß, (normal or symetric) (CH³)HC=
CH(CH³). Is formed by the action of alcoholic potassa on
secondary butyl iodide, CH³-CH2-CHI-CH³. Boils at +3°
and solidifies to a crystalline mass at 0°. Unites with HI,
regenerating secondary butyl iodide, and with bromine, forming
the bromide (CH³)HBrC-CH Br(CH³), which boils at 159°.
De Luynes obtained secondary butyl iodide by reducing
erythrite with a large excess of hydriodic acid (page 565).
3. Ethylethylene (ethyl-vinyl), (C²H³)HC-CH².—Is ob-
tained by the action of sodium on a mixture of ethyl iodide
and bromethylene.
C2H5 + BrHC-CH² + Na² NaI + NaBr + (C2H5)IIC=CH2
Boiling-point, -5°. It unites with HI, forming secondary
butyl iodide, and with bromine, forming the bromide CH-
CH2-CHBr-CH Br, boiling at 166°.
AMYLENES, OR PENTENES, CH10.
Several isomeric hydrocarbons are known of the composition.
CH10. They exist in unequal proportions in the product of
the reaction of zinc chloride on amyl alcohol, a product gener-
ally designated as amylene. It is prepared by heating amyl
alcohol with zinc chloride, and passing the vapors which are
given off into a well-cooled receiver. The product is rectified,
that portion being retained which passes below 40°. It is a
mixture of isomeric amylenes, whose boiling-points vary from
22 to 40°, and which result from the dehydration of amyl
alcohol.
We need only describe two of these isomeric hydrocarbons:
trimethylethylene, which constitutes the greater portion of the
mixture, and isopropylethylene.
Trimethylethylene or ordinary amylene may be obtained in
a pure state by dehydrating tertiary amyl alcohol (the hydrate
of amylene of Wurtz), which may be accomplished by simply
heating it.
(CH3)2=C(OH)-CH2-CH³
Tertiary amyl alcohol.
W
H20
(CH3)2C=CH(CH³)
Trimethylethylene.
It boils at 36°, and unites directly with hydriodic acid, form-
ing tertiary amyl iodide, (CH3)2CI-CH2-CH³, which boils at
129°.
520
ELEMENTS OF MODERN CHEMISTRY.
When bromine is poured into cooled amylene, the addition
of each drop produces a hissing noise, indicating a violent reac-
tion, and the product is a liquid amylene bromide, boiling be-
tween 170 and 180°. If the operation be performed upon crude
amylene, a mixture of several bromides will result. Trimethyl-
ethylene yields a bromide containing (CH³)²=CBr-CH Br-CH³.
Isopropylethylene is formed by the action of alcoholic potas-
sium hydrate on amyl iodide (Flavitzky).
CH3
CH3
CH-CH2-CH12[ HI
Amyl iodide.
=
CII³CII-CH=CH²
CIB
Isopropylethylene.
This body also exists in small quantity in the mixture of
hydrocarbons formed by the action of zinc chloride on amyl
alcohol. Boiling-point, 25°. It unites with hydriodic acid,
forming a secondary iodide, (CH3)2-CH-CHI-CH", which boils
at 137-139°. It combines with bromine, forming the bromide
(CH³)²=CH-CHBr-CH'Br, which boils between 180 and 190°.
Polymerides of Amylene.-By the action of zinc chloride
on amyl alcohol, there are formed, independently of amylene,
other hydrocarbons, among which are the polymeric modifica-
tions known as diamylene, CH20; triamylene, Cl5H0; tetra-
mylene, C20H (Balard, Bauer). These bodies are formed by
the union of one, two, three, or four molecules of amylene.
40
30
HYDROCARBONS OF THE SERIES C¹H²n—².
Among the more simple hydrocarbons is one which was dis-
covered by E. Davy, and which Berthelot has recently suc-
ceeded in preparing by various processes. It is acetylene, and
is the first member of a series which includes, among others,
the following hydrocarbons:
Acetylene C2H2 (E. Davy, Berthelot).
Allylene C3H4 (Sawitsch).
Crotonylene CII (E. Caventou).
Valerylene C³H³ (Reboul).
Acetylene, CH²=CH-CH.-This gas is produced by the
incomplete combustion of many organic substances rich in car-
bon (Berthelot).
If a few drops of ether be poured upon the surface of an
ammoniacal solution of cuprous chloride contained in a nar-
row jar, and its vapor be ignited, a brownish-red deposit of
acetylenide of copper will be formed and may be observed on
DIATOMIC ALCOHOLS.
521
flowing the liquid around on the sides of the jar. This reac-
tion is characteristic of acetylene.
This gas may be formed by the direct union of carbon and
hydrogen, as discovered by Berthelot, when the electric arc is
passed between carbon points in a vessel containing pure hydro-
gen. At the high temperature of the arc, the hydrogen com-
bines directly with the carbon, forming acetylene.
It is also formed when monobromethylene is heated with
amylate of sodium (the sodium compound of amyl alcohol)
(Sawitsch).
C²H³Br + C³H¹.ONa
CH? + CH"OH + NaBr
Monobrom- Amylate of sodium. Acetylene.
ethylene.
Amyl alcohol.
Acetylene is a colorless gas, having a peculiar and disagree-
able odor. It is quite soluble in water. It burns with a bright
but smoky flame. It forms two compounds with bromine, a
dibromide, C'H Br, and a tetrabromide, CH Br.
DIATOMIC ALCOHOLS, OR GLYCOLS.
The name glycols was given by Wurtz to the dihydrates of
the series of hydrocarbons, CnH2n. If ordinary alcohol be
ethyl hydrate, ordinary glycol is ethylene dihydrate.
C2H5.OH
Ethyl hydrate.
C²H⭑(OH)2
Ethylene dihydrate.
While alcohol reacts with a single molecule of a monobasic
acid to form a neutral ether, glycol can react with either one
or two molecules of a monobasic acid, thus forming two ethers.
In other words, while the monatomic alcohols contain but one
atom of hydrogen which is replaceable by a single radical of a
monobasic acid, glycol contains in the two groups OH two such
atoms of hydrogen, capable of being replaced by 2 radicals of
a monobasic acid, or one radical of a dibasic acid.
}
O
C2I15
C2H30
Ethyl acetate.
( C² II *)'
(C²II³O)2]
02
Ethylene diacetate.
02
(C2H+)"'
(C+II402)''
Ethylene succinate.
The glycols yield diatomic acids by oxidation.
There are isomeric glycols, or isoglycols, corresponding to
the isoalcohols which have already been defined (page 473).
41*
522
ELEMENTS OF MODERN CHEMISTRY.
Six glycols are now known, belonging to the series CnH2n+20².
Ethylene glycol, or glycol
DENSITY AT 0°. COILING-POINTS.
C2H6O2
1.125
C³H8Q2
1.051
197.5°
188-189°
•
C+II1002
1.048
183-184°
C5H1202
•
•
0.987
1770
C6II1402
0.9667
207°
C8H1602
Propylene glycol, or propylglycol.
Butylene glycol, or butylglycol
Amylene glycol, or amylglycol
Hexylene glycol, or hexylglycol
Octylene glycol, or octylglycol (Ph.
de Clermont)
•
It is to be remarked that all of the members of the above
series are not, strictly speaking, homologous.
The structure of the latter glycols is different from that
of ethylene glycol; they are isoglycols. The propylglycol
discovered by Wurtz is of this number. Normal propylglycol
has recently been discovered by Géromont, and obtained in a
pure state by Reboul.
The isomerism of the glycols, like that of the alcohols, is
due to the constitutions of their molecules, which can contain,
like the molecules of the alcohols, the following groups:
The primary group -CII2.0II
The secondary group =CII.OH
The tertiary group
= C.OH
Thus, ethylene glycol is primary, since it contains two groups,
CH2.OH.
The amylglycol derived from trimethylethylene is at the
same time secondary and tertiary.
Pinacone, which has already been mentioned (page 504), is
a tertiary glycol; it contains two groups (C.OH).
CH2.OH
CH2.OH
Glycol.
CH3
CH3
C.OH
CH3-CH.OH
Amylglycol.
CH3.
C.OH
CH3.
CH3.
C.OH
CH3
Pinacone.
(Tertiary.)
(Secondary and tertiary.)
Among the mixed glycols, that is, those containing at the
same time two different alcoholic groups, is ordinary propyl-
glycol, which is primary and secondary.
CH2.OH
CH2
CH2.OH
Normal propylglycol.
(Primary).
CH3
CH.OH
CH2.OH
Ordinary propylglycol.
(Primary and secondary).
GLYCOL.
523
GLYCOL, OR ETHYLENE DIHYDRATE.
C2H6O2 C²H¹(OH)2
Wurtz first obtained glycol by causing either iodide or bro-
mide of ethylene to react with silver acetate
C2H+12 +
Ag.C2H302
Ag.C2H302
Silver acetate.
C2H3O2
(C²H¹)'' { C2H302 + 2AgI
Ethylene diacetate.
and saponifying the resulting ethylene diacetate by potassium
hydrate.
C2H30.0
C2H30.0
} (C2H4)"' + 2KOH
=
2(C²H³0.0K) + (C²H³)'' {
Potassium acetate.
Ethylene diacetate.
Glycol.
он
он
Atkinson has shown that the silver acetate may be advan-
tageously replaced by an alcoholic solution of potassium ace-
tate. Bromide of ethylene reacts with the latter salt, forming
potassium bromide, which is almost insoluble in alcohol, and
ethylene acetate which is afterwards decomposed by caustic
potassa or caustic baryta.
Another process has been recently proposed by Hüfner and
Zöller. 188 grammes of ethylene bromide, 138 grammes of
potassium carbonate and 1 litre of water are introduced into a
large flask connected with a reversed condenser, and the mix-
ture is boiled until all of the ethylene bromide has disappeared.
The aqueous liquid is then concentrated on a water-bath, and
alcohol is added to precipitate the potassium bromide; the
alcoholic liquid is then distilled. Alcohol and water first pass,
and when the temperature rises above 150°, the liquid which
condenses is nearly pure glycol.
Properties.-Glycol is a somewhat syrupy, colorless, and
odorless liquid, having a sweet taste. It mixes with water and
alcohol in all proportions, but is scarcely soluble in ether.
boils at 197.5°, and distils without alteration.
Its analogy to alcohol, from which it differs by containing
one more atom of oxygen, is demonstrated by the following
experiments:
1. If platinum black be moistened with glycol and then
rapidly plunged into a jar of oxygen, a brilliant incandes-
cence is manifested immediately, due to the energetic absorp-
tion of oxygen.
524
ELEMENTS OF MODERN CHEMISTRY.
With dilute glycol, the oxidation is slower, and glycollic acid
is formed.
CH2.OH
CH2.OH +
Glycol.
02
CH2.0II
co.011 + 1120
Glycolic acid.
2. If glycol be heated with ordinary nitric acid, torrents of
red vapor are disengaged, and the liquid deposits crystals of
oxalic acid on cooling.
CH2.OH
CO.OH
CH².OH + 202
=
Glycol.
CO.OH + 2H2O
Oxalic acid.
3. When glycol is heated with potassium hydrate to 250°,
pure hydrogen is disengaged and potassium oxalate is formed.
C²H6O² + 2KOH
Glycol.
C²O¹K² + 4H²
Potassium oxalate.
These experiments establish between glycol and glycollie and
oxalic acids, relations analogous to those which exist between
alcohol and acetic acid.
Ethylene Chlorhydrate, or Ethylenic Chlorhydrin.-
When hydrochloric acid gas is passed into glycol, a neutral
compound is formed which constitutes the monochlorhydrin
of glycol, or ethylene chlorhydrate.
"
C2H+
OH
ΟΗ
HCI
+
Glycol.
OH
C2114
CI
Ethylene chlorhydrate.
+ H2O
This compound is intermediate between glycol and ethylene
chloride, which is the dichlorhydrin of glycol.
он
C2I14
он
Glycol.
он
C2H4
CI
Monochlorhydrin of
glycol.
CI
C2I14
CI
Dichlorhydrin of glycol
(ethylene chloride).
Ethylene chlorhydrate is also formed by the direct union of
ethylene gas and hypochlorous acid (Carius).
CH* + HClO = CH5C1O
It is a colorless liquid, having a density of 1.24 at 8°. It
boils at 130-131°.
Ethylene bromhydrate, or ethylenic bromhydrin, is formed
under circumstances analogous to those which furnish the
chlorhydrate. It is a thick, colorless liquid, boiling at 147°.
ETHYLENE OXIDE.
525
O.NO²
-он
is
Ethylene Nitrates.-By the reaction of ethylene brom-
hydrate on silver nitrate, at ordinary temperatures or by the
aid of gentle heat, ethylene mononitrate, C'H'<
obtained as a colorless or slightly yellow liquid, which is sol-
uble in water. Density at 11°, 1.31.
O.NO2
Ethylene dinitrate, C²H*<O.NO² is formed by the action
of ethylene bromide on an alcoholic solution of silver nitrate.
It is a mobile, colorless liquid, insoluble in water. Density at
8°, 1.4837. It explodes by percussion (Henry).
Ethylene Acetates.-When glycol is heated with acetic
acid, it is converted into acetic ethers.
он
C2H4
он
+ C2H30.0H
C2H+
O.C2H30
он
+
H20
Acetic acid.
OH
C2H4.
OH
+ 2(C2H³0.0H)
Ethylene monacetate.
O.C2H30
C2H4O.C²H³0
+ 2H20
Acetic acid.
Ethylene diacetate.
Ethylene monacetate, or monacetic glycol, is a liquid mis-
cible with water and alcohol, and boiling at 182°.
Ethylene diacetate, or diacetic glycol, can be prepared by the
reaction of ethylene iodide on silver acetate. It is a colorless
liquid, soluble in 7 parts of water; it boils at 186°.
It is thus seen that two neutral ethereal compounds can be
formed by the action of one and the same monobasic acid on
glycol, while the monatomic alcohols would furnish but a single
compound ether under the same circumstances.
ETHYLENE OXIDE.
C2H4O
CH2
2
If an excess of potassium hydrate be added to ethylene
chlorhydrate contained in a test-tube, and a gentle heat be
applied, a brisk effervescence will take place, due to a dis-
engagement of vapor which may be ignited at the mouth of
the tube.
At a low temperature, this vapor condenses to a colorless.
liquid, which is ethylene oxide.
C2H CIO
C2H¹O
Ethylene chlorhydrate. Ethylene oxide.
+ HCI
526
ELEMENTS OF MODERN CHEMISTRY.
Ethylene oxide has the composition of glycol, less the ele-
ments of one molecule of water.
C2H4O C2H6O2 H2O
However, it cannot be obtained by direct dehydration of
glycol, for when that body is distilled with zinc chloride,
among other products, aldehyde, which is isomeric with ethyl-
ene oxide, is obtained.
Greene has obtained ethylene oxide by double decomposi-
tion, by heating ethylene bromide with anhydrous sodium
oxide.
C²H¹Br² + Na³O
C2H4O2Na Br
Properties. Ethylene oxide boils at 13.5°. It dissolves
in all proportions in water, alcohol, and ether. Under the
influence of sodium amalgam and water, it fixes hydrogen
directly, being transformed into alcohol.
C²H¹O + H²: C2H6O
It combines directly with water at 100°, regenerating glycol.
C²H¹O + H2O = C2H6O2
It possesses basic properties.
If equal volumes of hydrochloric gas and vapor of ethylene
oxide be mixed over the mercury-trough (the mercury should
be slightly warmed) the two gases will disappear; they combine
to form a liquid which is ethylene chlorhydrate.
C²H¹O + HCl = C²H³CIO
If liquid ethylene oxide be added to a cooled solution of
magnesium chloride, an abundant precipitate of magnesium
hydrate will be formed in the course of a day, and the liquid
will contain ethylene chlorhydrate. Oxide of ethylene precipi-
tates magnesia as would a powerful base (A. Wurtz).
If a fragment of zinc chloride be allowed to fall into ethylene
oxide, the latter soon undergoes a curious, polymeric change,
and becomes solid (A. Wurtz).
Bases Derived from Ethylene Oxide.-Oxide of ethylene
combines with ammonia, yielding a series of bases, the hydrox-
ethylenamines, which are formed by the direct union of one,
two, or three inolecules of ethylene oxide with one molecule of
ammonia.
C2H4.OH
HN
H
C2H4.OH
C2H4.OHN
H
Hydroxethylenamine. Dihydroxethylenamine.
C2I14.0II
C2H4OHN
C2H4.OH
Trihydroxethylenamine.
ETHYLENE-DIAMINES.
527
These bases are also formed by the action of ammonia on
ethylene chlorhydrate.
C2H4.OH
C2H4
CI
OH
+ NH3
HN + HCI
H
When ethylene chlorhydrate is treated with trimethylamine,
the bodies combine, forming a chloride.
N(CH3)3 + C2H
OH
CI
C2H4.OH
(CH3)3)
N.CI
When this chloride is treated with water and silver oxide,
it is converted into a hydrate.
C2H4.OH
(CH3)3) N.OH
This hydrate is neurine, an energetic natural base which
exists in the bile (choline) and which is also a product of the
decomposition of a complex substance, lecithine, which exists.
in the brain, in the nerves, and in the yolk of eggs.
ETHYLENE-DIAMINES.
These bases result from the substitution of one, two, or three
ethylene groups, (C'H')", each for two atoms of hydrogen in
two molecules of ammonia.
They are formed by the reaction of an alcoholic solution of
ammonia on ethylene bromide at ordinary temperatures.
C2H4Br2 + 2NH3
C2H+(NH2)2.2 HBr
Ethylene-diamine
hydrobromide.
CH2-NH2
N2
{
(
(C²H¹)''
H2 is a liquid base,
Ethylene-diamine, CH²-NH² =№²
H2
boiling at 123°. By the prolonged action of an excess of
ethylene bromide, it is converted successively into diethylene-
diamine and triethylene-diamine.
(C2H4)"
N2 H2
H2
((C² H + ) !!
N² (C²II)''
H2
((C2H+)!!
N² (C²II)''
(C2H4)"
Triethylene-diamine.
Ethylene-diamine. Diethylene-diamine.
Diethylene-diamine boils at 170°, and triethylene-diamine at
210°. They are liquids. The ethlylene-diamines are diacid,
that is, they combine with two molecules of a monatomic acid,
such as hydrochloric or hydrobromic acid (Hofmann).
528
ELEMENTS OF MODERN CHEMISTRY.
ISETHIONIC ACID.
C2H6SO+
OH
C2H4
SO2.OH
This acid, which has long been known, attaches to the ethy-
lene derivatives. Oxide of ethylene unites directly with sodium
acid-sulphite (bisulphite), forming sodium isethionate.
C2H+.O + NaS03
H
C2H4
он
SO3 Na
Sodium isethionate.
The same salt is formed when ethylene chlorhydrate is heated
with neutral sodium sulphite.
C2H4.
OH
CI
+ Na2SO3
C2H4.
OH
SO³Na
+ NaCl
Isethionic acid may also be obtained by passing the vapor of
sulphuric anhydride into cold absolute alcohol or ether; the
liquid is then mixed with four times its volume of water, and
boiled for several hours, after which it is neutralized with
barium carbonate. The filtered liquid contains barium isethi-
onate, which, when exactly decomposed by sulphuric acid, fur-
nishes isethionic acid.
Isethionic acid is a sour liquid which cannot be entirely
deprived of water without decomposition.
Its salts are very
stable. It is isomeric with ethylsulphuric acid. Phosphorus
pentachloride transforms it into a chloride.
ΟΙΙ
C2H+ SO2.0K
Potassium isethionate.
+ 2PC15 C2114
་
Cl
SO2.CI + IICI + KCl + 2POCI
Chlorethylsulphurous
chloride.
The latter body is a liquid, boiling at 120°; it is decomposed
by the action of water at 100°, into chlorethylsulphurous acid
and hydrochloric acid.
Cl
Cl
C2H+ SO2.Cl
+ H20
C2H+ SO2.OH +
HCI
Chlorethylsulphurous acid.
TAURINE.
C'H'NSO³
This important acid, whose existence in the bile was dis-
covered by Gmelin in 1824, is related to isethionic acid; it is
amido-isethionic acid, that is, it is derived from the latter acid
PROPYLGLYCOLS-GLYCERIN.
529
by the substitution of a group NH² for a group OH. It may
be obtained by synthesis by the action of ammonia on chlor-
ethylsulphurous acid or on silver chlorethylsulphite. The fol-
lowing formulæ indicate the relations between isethionic and
chlorethylsulphurous acids and taurine:
C2H4
OH
SO2.OH
Isethiouic acid.
CI
C2H+
SO2.OH
Chlorethylsulphurous acid.
NH2
C²H⭑<S02.OH
Taurine.
Taurine crystallizes in large, brilliant, oblique rhombic prisms,
very soluble in boiling water and but slightly soluble in cold
water. When the crystals are heated they melt, and decompose
at an elevated temperature.
Strecker has obtained an isomeride of taurine by heating
ammonium isethionate.
C2H4
OH
-SO3(NH*)
C2H4<
Ammonium isethionate.
он
502.NH2
Isethionamide.
+ H20
PROPYLGLYCOLS.
C³H6(OH)2
Normal propylglycol (page 522) has been obtained from
normal propylene bromide (page 518). This bromide is mixed
with acetic acid and heated with silver acetate: propylene di-
acetate is formed, C³H (C²H³O²)², and separated by distillation,
after which it is decomposed by a quantity of dry potassium
hydrate just sufficient to remove its acetic acid.
Normal propylglycol is a colorless, syrupy liquid, boiling at
216, and having a density of 1.0652 at 0°. It is miscible
with water and alcohol in all proportions. When oxidized, it
yields hydracrylic acid (Géromont, Reboul).
Ordinary propylglycol is prepared from ordinary propylene
bromide by the same process indicated above. It is a thick,
colorless liquid, having a density of 1.051 at 0°. It boils at
188-189°. When diluted with water and mixed with plati-
num black, it absorbs oxygen, and is converted into lactic acid
(A. Wurtz)
GLYCERIN.
C3H803
C3H5(OH)3
Glycerin was discovered by Scheele in 1799, and studied by
Chevreul, Pelouze, and especially by Berthelot, who demon-
strated its character of a triatomic alcohol.
X
45
530
ELEMENTS OF MODERN CHEMISTRY.
Pelouze and Gélis realized the first artificial formation of a
fatty body by passing hydrochloric acid gas into a mixture of
butyric acid and glycerin: butyrin was thus produced.
Preparation. Glycerin is an accessory product in the man-
ufacture of lead plaster. When the preparation of that sub-
stance is terminated, the water is decanted from the lead soap
which separates, and hydrogen sulphide is passed through the
liquid in order to precipitate as sulphide any traces of lead that
may be dissolved.
It is then filtered and evaporated on a
water-bath. The glycerin remains as a colorless, syrupy liquid.
It is obtained in large quantities in the arts as an accessory
product in the manufacture of stearin candles.
Properties.-Glycerin is a colorless liquid, having a syrupy
consistence and a sweet taste. Its denstity at 15° is 1.28. It
dissolves in all proportions in water and alcohol, but is almost
insoluble in ether. When quickly heated, it distils between
275 and 280°; and it may be readily distilled in a vacuum.
Pure glycerin is crystallizable, and solidifies below 0°, but
solid glycerin melts only at 7 or 8° (Gladstone).
When subjected to the action of dilute nitric acid, glycerin
is converted into a triatomic acid, which is called glyceric acid
(Debus, Socoloff).
C³H³0³ + 0² = H²0 + C³H®O¹
Glyceric acid.
Glycerin.
When glycerin is poured drop by drop into a mixture of
concentrated nitric and sulphuric acids, cooled in a vessel of
cold water, oily drops of trinitroglycerin, CH (O–NO²)³, are
precipitated. It is a yellowish oil, which explodes with great
violence by percussion, by heat, or sometimes even sponta-
neously.
On account of this property, nitroglycerin is employed as an
explosive; but it is generally incorporated with inert matter,
such as finely-divided silica. Such mixtures are called dyna-
mites.
When heated with phosphorus iodide, P'I*, glycerin is con-
verted into allyl iodide (Berthelot and de Luca) (page 478).
ETHERS OF GLYCERIN.
Glycerin, CH(OH)³, which contains three groups OH, can
form three classes of ethers by the substitution of one, two, or
three monobasic acid radicals for as many atoms of hydrogen
ETHERS OF GLYCERIN.
531
in these hydroxyl groups. If acetic acid be heated with
glycerin, according to the proportions of the mixture, three
different acetic ethers of glycerin may be obtained, ethers which
Berthelot has designated as acetins.
он
O.C2H30
C2H30.OH + C3H5OH
H2O + C³H5OH
он
Acetic acid. Glycerin.
он
Monacetin.
он
O.C2H30
2(C2H30.OH) + C3H5OH
2H2O + C3H50.C²H³0
он
он
Diacetin.
он
O.C2H30
3(C2H30.0H) + C3H5OH
3H2O + C3H50.C2H30
он
O.C2H3O
Triacetin.
In the same manner, by the action of the hydracids upon
glycerin, neutral combinations are formed, analogous to the
chlorides of the radicals CnH2n+¹, as well as to the dichlo-
ride of ethylene and to ethylene chlorhydrate. These com-
pounds are formed by the substitution of one, two, or three
atoms of chlorine or bromine for as many hydroxyl groups in
glycerin.
{
Cl
OH
Monochlorhydrin.
OH
C3H5OH + HCI
CH5OH + H2O
он
он
C3H5OH + 2HCI
он
(OH
{
CI
C3115 CI+ 2H2O
OH
Dichlorhydrin.
Monochlorhydrin is a thick, colorless liquid, soluble in water
and alcohol, and sensibly soluble in ether. It boils at 227°.
Dichlorhydrin is a neutral, oily liquid, having a pronounced,
ethereal odor. It dissolves in ether. Its density is 1.137, and
it boils at 178°.
When dichlorhydrin is treated with a concentrated solution
of potassium hydrate, the elements of hydrochloric acid are
removed and a body is obtained which Berthelot has named
epichlorhydrin.
C3H5C12(OH) — IICI C3H5CIO
CH2C1
Dichlorhydrin.
CH
CH²
Epichlorhydrin.
532
ELEMENTS OF MODERN CHEMISTRY.
Epichlorhydrin is a mobile liquid, heavier than water, and
having an agreeable, ethereal odor. Its taste is at first sweet,
afterwards sharp and burning. It boils at 118-119°. It is
soluble in all proportions in alcohol and ether, but not in water.
It combines directly with hydrochloric acid, regenerating
dichlorhydrin. When heated for a long time with water, it
combines with one molecule of that liquid, forming monochlor-
hydrin.
C³H³CIO + H²0 = C³H³Cl(OH)²
When dichlorhydrin is heated with phosphorus pentachlo-
ride, the last hydroxyl group is removed, being replaced by
chlorine; trichlorhydrin is thus obtained.
Cl
C³ H³ Cl + PC15
он
Dichlorhydrin.
Cl
C3H5
CI + POC1³ + HCI
CI
Trichlorhydrin.
Berthelot has obtained a great number of glycerin ethers by
directly heating glycerin with acids. When the reaction
terminated (it is often very slow), he saturates the excess of
acid with calcium hydrate, and extracts the neutral fatty body,
that is, the ether of glycerin, with ether.
NATURAL FATTY BODIES.
The fats encountered in nature are glycerides, that is, ethers
of glycerin. The memorable researches of Chevreul have
shown that when these fats are methodically treated with
different solvents, various immediate principles are separated,
of which the most common are stearin, margarin, and olein.
They are the tristearic, trimargaric, and trioleic ethers of
glycerin.
C3H5
{
O.C18H350
O.C18H350
0.01811350
Stearin.
C3I15
{
O.C17H330
O.C17H330
0.017H330
Margarin.
O.C18H330
C8115
O.C18H330
O.C18H330
Olein.
When these glycerin ethers are subjected to the action of
alkalies, lime, or oxide of lead, in presence of boiling water,
they are decomposed, absorbing at the same time the elements
of water: glycerin and the acid are set free, and the latter
combines with the base forming a soap (see page 534). Thus,
when stearin is boiled with milk of lime, calcium stearate and
glycerin are formed. When olein is heated with water and
litharge, it yields lead oleate and glycerin.
Most of the natural fats are mixtures of these principles
NATURAL FATTY BODIES.
533
in various proportions, and to the number we may add tri-
palmitin.
Stearin, margarin, and palmitin are solids, olein is liquid.
In the fats, the solid principles predominate; the oils contain
a larger proportion of olein.
Stearin is extracted from tallow. That substance is dissolved
in boiling ether and made to crystallize. The crystals are
pressed, and the operation is repeated with them many times
until a substance is obtained which crystallizes in brilliant little
scales, fusible at 66.5°. They are but slightly soluble in alco-
hol and in cold ether, but freely soluble in boiling ether.
Pulmitin has been extracted, by the aid of boiling alcohol,
from palm-oil which has previously been submitted to heavy
pressure between sheets of porous paper. It melts at 60°
(Heintz).
Olein is the predominating principle of olive-oil and almond-
oil, from which it is difficult to obtain it in a pure state. Ber-
thelot has prepared triolein artificially by heating glycerin to
a temperature between 200 and 240° with an excess of oleic
acid. The mass thus obtained is treated with lime and ether;
the latter dissolves the triolein and leaves calcium oleate.
The ethereal solution is decolorized with animal charcoal and
mixed with eight times its volume of alcohol, which precip-
itates the triolein. When dried in a vacuum, triolein is an oil
which solidifies at 10°. Its density
Its density is between 0.90 and 0.92.
It is insoluble in water, and very slightly soluble in alcohol.
In contact with mercuric nitrate or with peroxide of nitrogen
(red vapors), olein is converted into a crystalline, solid, fatty
body, fusible at 32°, to which Boudet has given the name
elaidin.
Fat Oils and Drying Oils.-The oils of olives, sweet
almonds, rape-seed, beech-nuts, etc., acquire an acrid taste and
a disagreeable odor when they are long exposed to the air, but
they do not solidify. They are called fat, or non-siccative
oils.
Olive-oil is the type of this class. It is extracted by press-
ure from crushed olives, and has a greenish-yellow color; its
taste is sweet and agreeable; it is odorless. At a temperature
a few degrees above 0°, it becomes a solid mass. When agitated
with mercurous nitrate, it becomes solid, the olein which it
contains being transformed into elaidin. It becomes rancid by
exposure to the air.
45*
534
ELEMENTS OF MODERN CHEMISTRY.
When other oils, such as linseed, walnut, hemp-seed, poppy
and castor oils are exposed to the air, they thicken and finally
are converted into somewhat elastic, yellow, transparent masses,
species of soft varnishes. They are, therefore, called drying
oils, and are employed in the preparation of paints and varnishes.
The changes which oils undergo on contact with the air are
caused by an absorption of oxygen, and are accompanied by a
disengagement of more or less carbon dioxide. Every one is
familiar with the uses of the natural fatty bodies in the arts
and in domestic economy. Among the industrial applications,
we can only mention the employment of tallow and palm-oil in
the manufacture of candles, and certain other oils in the fabri-
cation of soaps.
Stearin Candles.-To convert tallow into stearin candles, it
is saponified by lime, that is, it is first converted into a lime
soap, which is then decomposed by sulphuric acid. The latter
acid causes the fatty acids to separate, and they solidify on
cooling. They are strongly compressed, first between warm,
and finally between hot plates, so that the oleic acid is ex-
pressed, while the fatty acids proper remain. This process,
which was invented by de Milly and Motard in 1829, consists,
as may be seen, in entirely saponifying the tallow by lime. In
1854, de Milly modified it by considerably reducing the amount.
of lime, and consequently the proportion of sulphuric acid
required. But it is then necessary to operate at higher tem-
peratures by the aid of superheated steam. The operation is
conducted in closed vessels, and with 2.5 parts of lime, 100
parts of tallow may be saponified at a temperature of 170 or
180°.
Palm-oil may be converted into candles by a still more
simple process, which consists in subjecting it to the action
of superheated steam at 300°. It is thus directly decom-
posed into fatty acids and glycerin, for the vapor of water,
at the high temperature employed, acts precisely as would an
alkali.
Soaps. In the south of Europe, and principally at Mar-
seilles, oils of inferior quality are used for the manufacture of
soap, and the oils of sesame and earth-nut have been employed
for this purpose for some years. These oils are saponified by
boiling them in large boilers with a weak solution of caustic
soda. The oil thus becomes pasty, the excess of oil making an
emulsion with the solution of soap which is first formed.
SOAP.
535
More concentrated soda lye containing common salt is then
added, and the saponification is finished by boiling; the soap,
which is insoluble in the concentrated lye, comes to the surface
of the liquid, and the lye is then drawn off. When the soap
is well made, the paste hardens on cooling; it has a bluish-gray
color, due to a ferruginous soap mixed with sulphide of iron.
The iron and sulphur are derived from the materials employed,
crude caustic soda containing a small quantity of iron. If this
paste be heated with about one-twelfth its weight of water, or
a very weak solution of caustic soda, it melts, and if the mass
be allowed to stand undisturbed, it will separate into two por-
tions, the lower and strongly-colored layer containing the more
dense ferruginous soap; the upper layer constitutes white soap.
When the latter is completely clarified by the deposit of the
ferruginous soap, it is drawn off into large moulds, where it solid-
ifies. White is thus obtained. If, on the contrary, mar-
bled soap be desired, the paste is frequently agitated during the
cooling. The colored part, that is, the ferruginous soap, thus be-
comes diffused throughout the whole mass, forming bluish veins.
soap
For some years, large quantities of soap have been prepared
by combining with caustic soda the oleic acid obtained as an
accessory product in the manufacture of stearin candles.
Soft soaps have potassa for their base. They are manufac-
tured from various oils, such as hemp, poppy, and linseed oils,
which are saponified by caustic potassa lye.
Saponification.—It will have been noticed that all of these
industrial operations have for their object the decomposition.
of neutral fats into fatty acids, either free or combined with
a base. This decomposition has received the name saponifi-
cation. It may be effected by the action of water and heat
alone, by the action of a base, or by the action of a powerful
acid, such as sulphuric acid (sulphuric saponification). In the
latter case, the acid acts upon the glycerin, forming a sulpho-
glyceric acid. Whatever process be employed to effect this
decomposition, the presence of water is always necessary, for
the elements of that liquid combine directly with the fatty
body which is decomposed, as Chevreul has very well shown.
In this respect, the decomposition of palmitin by superheated
steam may serve as a type for all reactions of this class.
O.C16H1310
C3H5 O.C16H310 + 31I20
O.C16H310
Palmitin.
OII
CH5OH +
3C16H310.0H
Glycerin.
Palmitic acid.
он
536
ELEMENTS OF MODERN CHEMISTRY.
POLYATOMIC AND POLYBASIC ACIDS.
These acids are related to the polyatomic alcohols, just as
the acids containing two atoms of oxygen, and which we have
already studied, are related to the monatomic alcohols.
The polyatomic acids are classed in several series, among
which we must consider in a special manner those which in-
clude glycollic and oxalic acids. As we have already scen,
these two acids are products of the direct oxidation of glycol.
Their homologues are related to the superior glycols.
GLYCOLS.
CH2.OH
CH2.OH
Glycol.
CH2.OH
ACIDS, CnH2n(3.
CH2.OH
со.он
Glycollic acid.
CH2.OH
ACIDS, CпII2n_204.
CO.OH
со.он
Oxalic acid.
CO.OH
CH2
CH2
CH²
CH2.OH
CO.OH
CO.OH
Normal propylglycol.
Hydracrylic acid.
Malonic acid.
CH3
CH3
сп.он
сн.он
CII2.OH
со.он
Isopropylglycol. Lactic acid of fermentation.
CII2.0II
CH2
CO.OII
CH2
CH²
CH2
CH2.OH
Normal butylglycol.
со.он
Succinic acid.
The first of the above series is that of glycol and the supe-
rior glycols. Among the latter, the true homologues of glycol
would be those which differ from the latter by nCH2, and of
which the formulae would consequently be analogous to that
of normal propylglycol. Ordinary propylglycol, which yields
lactic acid by oxidation, is an isomeride of normal propylglycol.
The second series is that of glycollic acid and its homologues.
They are derived from the corresponding glycols by the sub-
stitution of O for H2 in one group, CH2.OH They conse-
quently contain but one carboxyl group, CO.OH; they are
monobasic, for the hydrogen atom of the last group can be
replaced by a metal. It will also be noticed that they are at
the same time acids and alcohols,-acids by virtue of the carb-
oxyl, CO.OH, primary alcohols by virtue of the group CH2.OH,
or secondary alcohols by virtue of the group CH.OH.
GLYCOLLIC ACID.
537
The third series is that of oxalic acid and its homologues.
They are derived from the glycols by substitution of O2 for
2H2 in two groups, CH2.OH. They consequently contain two
carboxyl groups, CO.OH, and they are dibasic because the
H of each of these groups may be replaced by an equivalent
quantity of metal.
:
Between glycollic and oxalic acids there exists a remarkable
acid, because it is at the same time a monobasic acid and an
aldehyde it is glyoxylic acid. It contains C2H2O³, one more
atom of oxygen than oxalic aldehyde, which is called glyoxal,
CH2O2, and two atoms of hydrogen less than glycolic acid.
These relations of composition will be clearly seen from the fol-
lowing formula:
CH2.OH
CO.OH
Glycollic acid.
сно
CO.OH
Glyoxylic acid.
CHO
I
CHO
Glyoxal.
CO.OH
со.он
Oxalic acid.
Of all the acids which make up these series, we can only
consider glycollic and lactic acids, which are members of the
first, and oxalic and succinic acids, which belong to the second.
Besides these, we will briefly describe the intermediate com-
pounds, glyoxylic acid and glyoxal.
GLYCOLLIC ACID.
C2H+03: CH2(OH)-CO. H
This acid is formed by the oxidation of glycol. Strecker
and Socoloff discovered it in the product of the reaction of
nitrous anhydride upon glycocol, or sugar of gelatine (see page
545).
R. Hoffmann and Kekulé have shown that it is produced by
the action of an excess of potassium hydrate on monochlor-
acetic acid.
KC²H²CO² + KOH
Potassium monochloracetate.
KC KC²H³O³
Potassium glycollate.
When pure, this acid forms deliquescent crystals, which are
very soluble in water. It dissolves also in alcohol and in ether.
It has a strong acid reaction. When heated, it loses the ele-
ments of water, and is converted into glycollide, or glycollic
anhydride, CH²O², or C*H*O*.
C2H+O³
Glycollic acid.
H2O
C2H2O2
Glycollide.
**
538
ELEMENTS OF MODERN CHEMISTRY.
GLYOXYLIC ACID AND GLYOXAL.
Glyoxylic acid is formed by the action of dilute nitric acid
on alcohol. It may be prepared by pouring into a tall jar,
by means of a funnel-tube, alcohol of 80 per cent., water, and
fuming nitric acid, successively, so that the layers may not mix
at once. The whole is then left for about a week at a temp-
erature of 20°, so that the three layers may gradually mix by
diffusion. Gases are disengaged, and the product contains nitric
acid, glyoxylic and glycollic acids, several ethers and aldehydes,
and notably glyoxal. The liquid is distributed in flat plates
and evaporated to a syrupy consistence on a water-bath. The
residue is exhausted with water, neutralized with chalk, and fil-
tered. Alcohol is added to the filtered liquid, and precipitates
glyoxylate and glycollate of calcium. The alcoholic mother-
liquor contains glyoxal. The precipitate of calcium salts is
collected on a filter, pressed, and dissolved in boiling water.
The solution being allowed to evaporate spontaneously, the cal-
cium glyoxylate, which is least soluble, is deposited first. Gly-
oxylic acid may be isolated by decomposing an aqueous solution
of calcium glyoxylate by oxalic acid.
Glyoxylic acid is a syrupy and very acid liquid. Its consti-
tution shows it to be at the same time an acid and an aldehyde,
and this double function is expressed by the formula
CHO.
CO.OH
Its solution reduces ammoniacal silver nitrate. When heated
with sulphuric acid it disengages carbon monoxide.
C2H2O3 2CO + H2O
Nascent hydrogen converts it into glycollic acid.
C²H²O³ + H² = C2H4O3
Glyoxal. This body is formed at the same time as the pro-
ducts above mentioned, by the action of weak nitric acid on
alcohol. It is prepared from the alcoholic solution which sepa-
rates from the calcium glycollate and glyoxylate. To this is
added a concentrated solution of sodium acid-sulphite, which
forms a crystalline combination with the glyoxal. This com-
bination deposits and is collected, purified by recrystallization
in water, and barium chloride is added to its aqueous solution.
A sulphite of glyoxal-barium is formed by double decomposi-
tion, and deposits in crystalline crusts. To its solution in boil-
LACTIC AND PARALACTIC ACIDS.
539
ing water sulphuric acid is added in quantity exactly sufficient
to precipitate the barium as sulphate. The filtered liquid will
contain sulphurous acid and glyoxal, and the latter alone will
remain after evaporation on a water-bath.
Glyoxal is a deliquescent, amorphous solid, slightly colored,
and very soluble in water and alcohol. Its aqueous solution
energetically reduces ammonio-nitrate of silver. It combines
with the acid-sulphites, like the other aldehydes. Glyoxal is
the aldehyde corresponding to oxalic acid.
CHO
спо
Glyoxal.
CO.OII
CO.OH
Oxalic acid.
LACTIC AND PARALACTIC ACIDS.
С³H60³ = CH³-CH(OH)-CO.OH
C3H603
Formation and Constitution.-Lactic acid was discovered
by Scheele in sour milk. Berzelius discovered the existence in
various liquids of the animal economy of an acid which was at
first believed to be identical with that which results from the
acid fermentation of milk. Later, an acid identical with the
latter was found in various vegetable juices, and was recog-
nized to be the product of a peculiar fermentation of glucose,
called the lactic fermentation. It was also discovered that
the lactic acid of fermentation is not identical with that which
exists in the animal liquids, especially that liquid which im-
pregnates the muscular fibres. The latter acid is called para-
lactic acid. The nature of its isomerism with lactic acid has
been recently discovered by Wislicenus. It is a case of phys-
ical isomerism; paralactic acid is optically active, and this
physical peculiarity carries in its train slight modifications in
chemical properties; these variations will be indicated when
treating of the lactates.
Independently of the acids which have just been mentioned,
there is another which was at first named ethylene-lactic acid,
and which results from the oxidation of normal propylglycol;
its constitution is expressed by the formula
CH2.01
сна
со.он
It is hydracrylic acid; it is also formed when ẞ-iodopropi-
onic acid is treated with water and silver oxide.
Its character-
540
ELEMENTS OF MODERN CHEMISTRY.
istic property is its easy decomposition into water and acrylic
acid, hence the name hydracrylic (Wislicenus).
Its isomeride, lactic acid of fermentation, is formed by the
oxidation of ordinary propylglycol (A. Wurtz). This fact
determines its constitution, which can also be deduced from
a very interesting mode of formation discovered by Strecker.
When a mixture of aldehyde, hydrocyanic acid, and hydro-
chloric acid is allowed to stand for some time, ammonium chlo-
ride and lactic acid are formed.
CH3
CII3
CHO
+ CNH + HCl + 2H2O
Aldehyde. Hydrocyanic
acid.
==
NH4Cl + CH.OH
CO.OH
Lactic acid.
The isomerism of lactic and hydracrylic acids may be readily
understood by the aid of the following formula:
CH2.OH
CH2
CH3
1
CH.OH
со.он
Hydracrylic acid.
CO.OH
Lactic acid.
Both acids are monobasic; each contains the group CO.OH,
which is characteristic of organic acids.
The third oxygen
atom exists in alcoholic hydroxyl, either in the primary group
CH2.OH, or in the secondary group CH.OH.
The preceding formulæ show that lactic acid has a mixed
function; it is at the same time an alcohol and an acid. This
made evident in all of its compounds, and it will be sufficient
to mention that one molecule of lactic acid in its function as
an acid, can react with and etherify another molecule in its
function of an alcohol, the hydroxyl of the group CO.OH
forming a molecule of water with the hydrogen of the alco-
holic hydroxyl in the second molecule of the acid.
dilactic acid, lactic anhydride, and lactide which are formed by
the more or less complete dehydration of two molecules of
lactic acid, are veritable dilactic ethers. This point has been
developed by Grimaux.
The
Preparation of Lactic Acid.-A mixture of 3 kilo-
grammes of glucose dissolved in 13 litres of water, 4 kilo-
grammes of sour milk, 100 grammes of old cheese, and 1.5
kilogrammes of pulverized chalk, is exposed to a temperature
of 30 or 35°. At the end of a week, the whole solidifies to
PARALACTIC ACID.
541
a mass of calcium lactate. The salt is purified by crystal-
lization, and is exactly decomposed by dilute sulphuric acid.
The calcium sulphate is separated by filtration, and the acid
liquid is boiled and saturated with hydrocarbonate of zinc;
It is then filtered and allowed to cool. The zinc lactate crys-
tallizes, and its solution being decomposed by hydrogen sul-
phide, zinc sulphide and lactic acid are obtained. The latter is
separated by filtration and its solution concentrated on a water-
bath.
Properties. Lactic acid is a colorless, syrupy liquid, having
a decided acid taste. When heated, it begins to lose water at
130°, and is converted, little by little, into a yellow, amorphous
mass, insoluble in water, but soluble in alcohol and ether. This
body is dilactic acid, CH¹005.
2C3H6O³ CH¹º05+ H2O
At 230°, it disengages a small quantity of carbon monoxide
and carbon dioxide, and a product distils which often solidifies
on cooling. It is lactide, or dilactic anhydride, and is derived
directly from dilactic acid.
C6H1005
Dilactic acid.
CH*O* + HO
+
Lactide.
Lactide has been represented by the more simple formula
CH+O², but L. Henry has shown by a determination of vapor
density that the double formula represents the true constitution
of this body. Grimaux had already arrived at the same con-
clusion from theoretical considerations.
Lactide occurs in colorless crystals, soluble in water and
alcohol. It possesses the property of combining directly with
the elements of water, lactic acid being reformed; it also com-
bines with ammonia, forming lactamide.
Paralactic Acid. This is the lactic acid which may be
extracted from meat. It is also called sarcolactic acid. It may
be prepared from commercial extract of meat; this is dissolved
in 4 parts of water, and the solution precipitated by 8 parts
of 90 per cent. alcohol. The alcoholic solution is decanted,
and the residue, which is insoluble in alcohol, is exhausted with
2 parts of lukewarm water, the solution again being precip-
itated by alcohol. The alcoholic solutions are united and dis-
tilled on a water-bath. The residue is rendered strongly acid
by sulphurous acid, and agitated with ether which dissolves the
46
542
ELEMENTS OF MODERN CHEMISTRY.
paralactic acid set free. The ethereal solution is evaporated,
and the acid is converted into the salt of zinc, which is subse-
quently decomposed by hydrogen sulphide, as has been indicated
for the preparation of ordinary lactic acid. Paralactic acid is
syrupy like its isomeride. It turns the plane of polarized light
to the right (Wislicenus). When heated, it becomes dehy-
drated, yielding lactide.
According to Wislicenus, extract of meat contains still an-
other paralactic acid, isomeric with the preceding, but optically
inactive.
Lactates and Paralactates.-Lactic acid is a monobasic
acid; the neutral lactates contain R'CHO³, or M"(C³H³O³)².
The most characteristic is zinc lactate, Zn(CH5O3)2 + 3H2O,
which is but slightly soluble in cold water, and separates from
its boiling solution in brilliant needles or laminæ.
Zinc paralactate crystallizes with two molecules of water,
and is much more soluble than the ordinary lactate.
Calcium lactate, Ca(C³HO3)2 + 5H2O, crystallizes in
rounded masses, formed of little needles grouped around a
common centre. Like all the lactates, it is very soluble in
water and alcohol. Its isomeride, calcium paralactate, is
deposited from boiling water with 4 molecules of water of
crystallization. According to Wislicenus, this salt contains
2[Ca(C³H³O³)²] + 9H²O.
Ferrous lactate, Fe(CHO)2, prepared by double decompo-
sition of calcium lactate and ferrous sulphate, forms greenish,
crystalline crusts, soluble in water. It is employed in medicine.
Lactamide, CH'NO².—When an alcoholic solution of lac-
tide is treated with ammonia and the liquid is evaporated,
crystals are obtained which are soluble in water and alcohol.
They constitute lactamide.
CHO + 2NH3
20³H'NO²
Potassium hydrate decomposes lactamide into lactic acid and
ammonia.
Lactamide represents ammonium lactate less the elements
of water.
CH3
сн.он
C0.0(NH4)
Ammonium lactate.
CH3
II20
сн.он
CO.NH2
Lactamide.
HYDRACRYLIC ACID.
543
HYDRACRYLIC ACID.
(ETHYLENELACTIC, OR ETHENELACTIC ACID.)
C3H6O3 = CH2(OH)-CH2-CO.OH
This acid is formed by the oxidation of normal propylglycol.
It is also formed by the action of water and silver oxide on
B-iodopropionic acid.
CH'I-CH2-CO'H + AgОH*
B-Iodopropionic acid.
CH2.OH-CH2-CO.OH + AgI
Hydracrylic acid.
The silver salt formed in the latter reaction is converted into
the zinc salt, and the latter is decomposed by hydrogen sul-
phide.
Hydracrylic acid is syrupy.
into acrylic acid and water.
When heated, it breaks up
C3H6O3 C³H¹0² + H2O
When heated with hydriodic acid, it is again converted into
B-iodopropionic acid. Its sodium salt, NaC HO³, deposits from
alcohol in crystals fusible at 142-143°. Between 180 and 200°,
it loses water, and is partly converted into sodium acrylate.
Zinc hydracrylate, Zn(CH5O3)2 + H2O, is characteristic.
It forms large, very brilliant crystals, soluble in about one part
of water.
C3H604
GLYCERIC ACID.
CH²(OH)-CH(OH)—CO.OH
This acid is obtained by oxidizing glycerin with nitric acid,
or by treating it with bromine and water. It is also formed
by the spontaneous decomposition of nitroglycerin.
It is prepared by introducing into a tall jar one part of nitric
acid of specific gravity 1.5, and 1 part of glycerin diluted with
its own volume of water. Care is taken that the two liquids may
not mix, and the whole is left to itself for five or six days. The
two bodies gradually mingle and react upon each other.
liquid is evaporated on a water-bath, and the residue is boiled
with well-washed hydrate of lead suspended in water, after
which the solution of lead-salt is filtered hot. Crystals of lead
Instead of Ag20 + H20.
The
544
ELEMENTS OF MODERN CHEMISTRY.
glycerate separate on cooling; they are purified, and their
aqueous solution when decomposed by hydrogen sulphide, fur-
nishes glyceric acid.
Properties. Glyceric acid is a thick, light-yellow syrup,
soluble in water and alcohol. Its reaction is acid; it is mono-
basic. Hydriodic acid, by the aid of heat, converts it into
B-iodopropionic acid. Its relations with glycerin may be seen
in the following formula:
CH2.OH
сн.он
CH2.OH
Glycerin.
CO.OH
сн.он
CH2 OH
Glyceric acid.
Closely related to glycollic and lactic acids are two important
nitrogenized bodies, glycocol and alanine. They form part of
a series which includes among other bodies leucine, a nitro-
genized compound which plays a part in the animal economy.
When a current of nitrous anhydride is passed into solutions
of glycocol, alanine, and leucine, nitrogen is disengaged, and
these bodies are converted into glycollic, lactic, and leucic acids.
We then have the following series:
C²H¹O³
Glycollic acid.
C3H6O³
Lactic acid.
C6H1203
Leucic acid.
GLYCOCOL.
C²H³NO²
Glycocol.
C³H'NO²
Alanine.
C6H13 NO²
Leucine,
C2H5NO = CH2(NH2)-CO OH
This body is related to glycollic acid. It was discovered by
Braconnot, who obtained it by boiling gelatin with dilute sul-
phuric acid for a long time, saturating the solution with barium
carbonate and evaporating the filtered liquid. Hence the name
sugar of gelatin or glycocol.
Cahours obtained it by the action of ammonia on mono-
chloracetic acid.
CO.OH
+ 2NH3
NH4Cl +
Cн²CI
Monochloracetic acid.
It is therefore amidacetic or acetamic acid.
CO.OH
CHI2.NH2
Glycocol.
ALANINE.
545
It is a solid body, crystallizing in oblique rhombic prisms,
fusible at 170°. Its taste is sweet. It is soluble in water,
slightly soluble in alcohol, insoluble in ether. Its solution has
a feeble acid reaction. Indeed, glycocol can react with the
bases, forming compounds; when it is digested for several hours
at a temperature between 80 and 104° with silver oxide, the
latter is dissolved, and the compound C'H+AgNO² is formed.
On the other hand, glycocol will combine with the acids; there
is a crystallizable nitrate of glycocol.
When nitrous anhydride is passed into a solution of glycocol,
the latter is converted into glycollic acid, nitrogen being at the
same time disengaged.
2C²H³NO² + N²O³ = 2C²H¹O³ + H²O + 2N²
Glycocol.
Glycollic acid.
ALANINE.
C3H7N02
CH3-CH(NH2)CO.OH
Strecker made the synthesis of alanine by passing hydro-
chloric acid gas into a mixture of aldehyde-ammonia and hydro-
cyanic acid.
C²H¹O + CNH + H2O =
C³H NO²
The brown liquid resulting from this reaction is evaporated.
Alanine crystallizes in hard needles, grouped in stars or tufts.
It is soluble in water, only slightly soluble in alcohol, insoluble
in ether. The aqueous solution is neutral, and is converted
by nitrous anhydride into lactic acid, with evolution of nitrogen.
2C³H¹NO² + N²O³
Alanine.
2C³H®O³ + H³0 + 2N²
Lactic acid.
Alanine may be sublimed by cautiously heating it. By dry
distillation, it breaks up into carbon dioxide and ethylamine.
C³H'NO² CO + CH.NH
2
It is isomeric with lactamide and with an acid amide which
is obtained by the action of ammonia on ẞ-iodopropionic acid.
The following formulæ account for these isomerides:
CH3
сн.он
CO.NII2
Lactumide.
CH2.NH2
CH2
B-amidopropionic acid.
CH3
CHÍNH
CO.OH
Alanine.
46*
546
ELEMENTS OF MODERN CHEMISTRY.
B-amidopropionic acid, which is formed in the reaction just
indicated, crystallizes in transparent and colorless oblique.
rhombic prisms. It is very soluble in water and but slightly
soluble in alcohol. When cautiously heated to 170°, it partly
sublimes in needles.
LEUCINE.
C6H13NO2
This body was discovered by Proust, in 1818, in old cheese.
It seems to be identical with a substance obtained from cadav-
eric fat, and named by Foureroy aposepedine. It is a product
of the putrefaction of animal matters. It is also formed when
horn, gelatinous tissues, or albuminous matters are boiled with
dilute sulphuric acid, or fused with potassium hydrate. In
these reactions, tyrosine, and sometimes glycocol, is formed at
the same time.
Leucine exists already formed in the economy. It is met
with in the tissues of the liver, spleen, lungs, pancreas, and
in the salivary glands, etc. Limpricht has formed it artifi-
cially, by a process analogous to that employed by Strecker for
the synthesis of alanine.
Preparation. The best process for the preparation of leu-
cine, consists in boiling for twenty-four hours 2 parts of horn-
shavings with 5 parts of sulphuric acid and 13 parts of water,
care being taken to replace the water as it evaporates. The
liquid is neutralized with milk of lime, the calcium sulphate
separated by filtration, and a small quantity of lime that re-
mains in solution is precipitated by oxalic acid. The filtered solu-
tion, left to itself, first deposits tyrosine, and the leucine remains
in the mother-liquor, from which it separates in crystals on spon-
taneous evaporation. It is finally crystallized from weak alcohol.
Properties.-Leucine crystallizes in white plates. It dis-
solves in 27 parts of cold water and much more abundantly in
boiling water. It melts at 170°, and decomposes at a higher
temperature into carbon dioxide and amylamine.
13
C6H¹³NO² COCH" NH²
When nitrous anhydride is passed into a solution of leucine,
it is converted into a homologue of lactic acid, leucic acid
(Strecker).
13
2C6H¹³NO² + N²O³
2C6H¹²O³ + H2O + 2N²
Leucic acid.
OXALIC ACID.
547
OXALIC ACID.
C2H2O+
CO(OH)-CO(OH)
Natural State and Modes of Formation.-This important
acid exists in many vegetables. Wiegleb and Scheele extracted
it from salt of sorrel, which is an acid oxalate of potassium.
The process of Scheele has become classic. It consists in
precipitating a solution of salt of sorrel with acetate of lead,
and decomposing the precipitated lead oxalate by hydrogen
sulphide. The great Swedish chemist demonstrated the iden-
tity of the acid thus formed and that which Bergman had
anteriorly obtained by treating sugar with nitric acid.
Oxalic acid is met with in the animal economy. Urine often
deposits little crystals of calcium oxalate, which salt is some-
times deposited in the bladder and there forms rough concre-
tions known as mulberry calculi.
Oxalic acid is formed by the action of nitric acid or fused
potassium hydrate on a great number of organic matters.
Cyanogen yields oxalic acid by its decomposition in contact.
with water (page 431).
We have already studied the relations which exist between
oxalic acid and glycol (page 524).
Drechsel has recently made a beautiful synthesis of oxalic
acid. By passing carbon dioxide upon sodium disseminated in
very dry quartz sand and heated to 350°, he obtained sodium
oxalate.
200² + Na²
Na2C2O*
Sodium oxalate.
Preparation.-Oxalic acid is prepared in the arts by two
processes. One consists in the oxidation of molasses of an
inferior quality by nitric acid. The operation gives rise to an
abundant disengagement of nitrous vapors and carbon dioxide.
It is conducted in leaden boilers that are not attacked in pres-
ence of a great excess of oxidizable organic matter.
Another process consists in the reaction of potassium hy-
drate on saw-dust at a high temperature. The mass is ex-
hausted with water which dissolves out potassium oxalate, and
the solution is treated with milk of lime. Calcium oxalate
precipitated and potassium hydrate is reformed. The precip-
itated calcium oxalate is decomposed by sulphuric acid, calcium
sulphate, which is almost insoluble, being formed, and oxalic
548
ELEMENTS OF MODERN CHEMISTRY.
acid remaining in solution in the water. When the latter is
sufficiently concentrated, the acid is deposited in crystals. The
potassium hydrate which remains in the first solution is evapo-
rated, and serves for new operations.
Properties.-Oxalic acid crystallizes from its aqueous solu-
tion in large, transparent prisms, containing 2 molecules of
water. When exposed to the air, these crystals effloresce, and
they completely lose their water at 100° or in a dry vacuum.
One part of oxalic acid dissolves in 15.5 parts of water at 10°.
It is also very soluble in alcohol.
It melts in its water of crystallization at 98°; at 132° it
begins to disengage gases, and between 155 and 160° it breaks
up into water, carbon monoxide, carbon dioxide, and formie
acid.
C2H2O+
C2H2O+
CO² + CH20²
CO² + CO + H2O
At the same time, a portion of the dry acid escapes decompo-
sition and sublimes.
When oxalic acid is heated with sulphuric acid, it is de-
composed into carbon monoxide, carbon dioxide, and water,
according to the equation given above.
:
Certain chlorides are reduced by ebullition with a solution
of oxalic acid hydrochloric acid is formed, and carbon dioxide
is disengaged. Under these circumstances, auric chloride de-
posits metallic gold; mercuric chloride is reduced to mercurous
chloride.
Oxalic acid is a violent poison. In doses of 8, 12, to 20
grammes, it produces poisonous effects which may prove fatal.
It acts upon the heart, retarding its movements, and upon
nerve centres, of which it rapidly depresses the functions.
the
If a solution of oxalic acid, or better, ammonium oxalate,
be added to a solution of calcium chloride, a white precipitate
of calcium oxalate is formed. This precipitate is formed even
in very dilute solutions. If a small quantity of silver oxalate
be heated in a small test-tube, the salt decomposes suddenly
with a slight explosion, leaving a gray powder of metallic
silver, part of which is violently projected from the tube.
Ag2C2O4 200² + Ag²
Silver oxalate.
These reactions characterize oxalic acid.
Oxalates. Oxalic acid is dibasic. Its two atoms of hydro-
OXAMIDE.
549
gen may be replaced by two atoms of a univalent metal, or by
one atom of a bivalent. Acid oxalates and neutral oxalates
are known.
Potassium Acid Oxalate, KHCO + H2O.—This salt con-
stitutes the greater part of the salt of sorrel of commerce. It
is extracted from the juice of various kinds of Rumex and
Oxalis, the juice of which is clarified with clay and then
evaporated to crystallization. It is but slightly soluble in
water.
If a concentrated solution of oxalic acid be agitated with a
solution of potassium neutral oxalate, a precipitate of potassium
acid oxalate will be formed.
If a concentrated solution of oxalic acid be agitated with
a solution of potassium acid oxalate, a white precipitate of
potassium quadroxalate, a combination of the acid salt and
oxalic acid, will be deposited. It contains C2H2O* + KHC²O¹
+ 2H2O.
Neutral Potassium Oxalate, K2C2O4 + H2O, is obtained
by neutralizing a solution of the acid salt with potassium car-
bonate and evaporating. It crystallizes in oblique rhombic
prisms, very soluble in water.
Ammonium Oxalate, (NH4)2C2O4 + H2O, which is fre-
quently used as a reagent, is prepared by neutralizing oxalic
acid with ammonia. The concentrated solution deposits color-
less crystals belonging to the type of the right rhombic prism.
There is also an acid oxalate of ammonia, (NH) HC²O¹.
Ethyl Oxalate, or Oxalic Ether, (CH)2CO-This ether
may be prepared by distilling a mixture of 1 part of potassium
acid oxalate, 1 part of alcohol, and 2 parts of concentrated
sulphuric acid. The addition of water to the distilled liquid
causes the separation of an oily layer which sinks and is de-
canted. It is washed with a solution of an alkaline carbonate,
and distilled, only that portion being retained which passes
above 180°. Oxalic ether is a colorless liquid, heavier than
water, and having an aromatic odor. It boils at 186°.
OXAMIDE.
C202(NH2)2
If solution of ammonia be added to ethyl oxalate, the latter
immediately solidifies to a white mass formed of a crystalline
powder. This is oxamide.
550
ELEMENTS OF MODERN CHEMISTRY.
C2H5.0
C2H5.0
C202 + 2NH3
C202 NII2
NH2
+ 2(C2H5.OH)
Ethyl oxalate.
Oxamide.
Oxamide is also formed by the dry distillation of ammonium
oxalate.
NH+.0
NH+.0
C202 C202
NII2
NII2
+ 2H2O
The latter reaction, studied in 1830 by Dumas, led to the
discovery of the amides.
Oxamide is a white, crystalline powder, very slightly soluble
in cold water, insoluble in alcohol, somewhat soluble in boiling
water, from which it is deposited on cooling. Like all of the
amides, it is decomposed by boiling potassium hydrate, am-
monia being disengaged and potassium oxalate formed.
Oxamic Acid. This body is formed when ammonium acid
oxalate is heated to between 220 and 238° (Balard).
NHAO
HO
C202
C202.
NH2
он
Oxamic acid.
+ H20
Ammonium acid oxalate.
It is a yellowish, grainy powder which boiling water again
converts into ammonium acid oxalate by the direct addition of
one molecule of water.
The following formulæ express clearly the relations existing
between oxalic acid, oxamic acid, and oxamide:
C202
OH
OH
Oxalic acid.
C202<
NH2
OH
Oxamic acid.
NH2
C202
NII2
Oxamido.
SUCCINIC ACID.
C411604 CO.OH-CH2-CH2-CO.OH
This acid, which was first obtained by the distillation of
amber, is one of the products of oxidation by nitric acid of the
complex fatty acids, such as palmitic and stearic acids. It is
also formed by the fermentation of calcium malate and by the
reduction of malic and tartaric acids by hydriodic acid.
Maxwell Simpson obtained it synthetically by decomposing
ethylene dicyanide with potassium hydrate.
CH2-CN
CH2-CO.OH
+ 4H20
CII2-CN
1
+ 2NH3
Ethylene dicyanide.
CH2-CO.OH
Succinic acid.
In this reaction the nitrogen of each cyanogen group unites
SUCCINIC ACID.
551
with H³, and is replaced by O'H=2(H2O) — H². Succinic.
acid then contains two groups CO2H, combined with ethylene.
It is dibasic.
Preparation.-Succinic acid may be prepared either by the
dry distillation of amber and purifying the solid product of
this distillation, or by exposing for some time calcium malate
mixed with a small quantity of white cheese to a temperature
of 30 or 40°. By a sort of fermentation the malate is then
converted into succinate, and the calcium succinate, being de-
composed by dilute sulphuric acid, yields calcium sulphate,
which is separated by filtration, and a solution of succinic acid
which crystallizes after concentration.
Properties. Succinic acid forms large, colorless crystals, un-
altered by the air, and fusible at 180°. At 235° it boils and
breaks up into succinic anhydride and water.
C4H6O+
Succinic acid.
C*H*O3 + HẢO
Succinic anhydride.
It is quite soluble in water, less so in alcohol, and almost in-
soluble in ether.
When subjected to dry distillation, it loses one molecule of
water, and is converted into succinic anhydride, C*H*O³, which
forms a white, crystalline mass. The latter body is converted
by phosphorus pentachloride into succinyl chloride, C'H'O'CP.
CII2-CO
CH2-CO
CH₂-COO
Succinic anhydride.
CH2-COCI
+ PC15
POCI3 +
CH²_COCI
Succinyl chloride.
Kekulé has obtained monobromo-succinic and dibromo-suc-
cinic acids by heating moistened succinic acid with bromine in
sealed tubes.
Monobromo-succinic acid is converted into malic acid when
treated with water and silver oxide.
CO2H
C² H³ Br<CO² II
Monobromo-succinic acid.
+ AgOH
CO2H
C²H³ (OH) CO²H
Malic acid.
+ AgBr
Under the same circumstances, dibromo-succinic acid is con-
verted into tartaric acid.
CO2H
C²H² Br² <CO² II
+ 2AgOH
CO2H
C² H²(OH)² <CO²II
+ 2AgBr
Dibromo-succinic acid.
Tartaric acid.
These reactions, which were discovered by Kekulé, establish
very close relations between succinic, malic, and tartaric acids.
552
ELEMENTS OF MODERN CHEMISTRY.
C4H604 succinic acid.
C4H605 malic acid.
C4H606 tartaric acid.
The following formulæ express the constitutions of these
acids:
CH2-CO.OH
CH2-CO.OH
succinic acid.
CH(OH)-CO.OH
malic acid.
CH²_CO.OH
CH(OH)-CO.OH
CH(OH)-CO.OH
tartaric acid.
Malic acid is oxysuccinic acid, and tartaric acid is dioxysuc-
cinic acid. By reducing agents, the latter acids can be con-
verted into succinic acid. When either of them is heated with
a large excess of hydriodic acid, water is formed, iodine is de-
posited, and the liquid will be found to contain succinic acid
(Schmitt and Dessaignes).
C¹H6О5
MALIC ACID.
CO.OH-CH2-CH(OH)-CO.OH
This acid, which exists in a number of vegetables, was ex-
tracted by Scheele from apple-juice. It is generally prepared
from the berries of the mountain-ash, gathered before their
complete maturity; they are strongly pressed, and the juice is
boiled, filtered, and neutralized with milk of lime at the ordi-
nary temperature. Calcium malate is deposited, and this is
converted into the acid malate by dissolving it in boiling water
acidulated with nitric acid. The calcium acid malate may be
readily purified by crystallization, after which it is converted
into malate of lead by double decomposition with lead acetate.
The lead salt is suspended in pure water and decomposed by
hydrogen sulphide; the solution of malic acid is then filtered
and evaporated (Liebig).
Properties.-Malic acid crystallizes in little needles grouped
in rounded grains. These deliquesce when exposed to the air.
The aqueous solution of malic acid has a marked acid taste.
When long kept, it becomes filled with vegetations. It de-
viates the plane of polarization to the left. However, there is
an inactive malic acid which has no effect on polarized light
ASPARAGIN.
553
(Pasteur). Solution of malic acid does not produce a cloud in
lime-water, neither in the cold, nor on boiling.
When malic acid is heated, it begins to lose water at 130°,
and between 150 and 200° is converted into two acids which
are isomeric with each other, and are known as maleic and
fumaric acids.
C4H605
Malic acid.
C*H*O*
+
H2O
Maleic and fumaric acids.
By the action of potassium hydrate at about 150°, malic
acid is decomposed into oxalic and acetic acids.
CH°05 + H2O
Malic acid.
C²H²O¹ +
+ C²H¹O² + H²
Oxalic acid.
Acetic acid.
ASPARAGIN AND ASPARTIC ACID.
Succinic and malic acids present simple and remarkable rela-
tions with two nitrogenized bodies which have long been known;
they are asparagin and aspartic acids.
The latter body is amidosuccinic acid, and bears the same
relations to succinic acid that glycocol (amido-acetic acid) bears
to acetic acid. On the other hand, its relations to malic acid
are analogous to those of glycocol to glycollic acid.
CH³
со.он
CH2.OH
CO.OH
Glycollic acid.
CH2.NH2
CO.OH
Glycocol.
Acetic acid.
CII2-CO.OH
CH2-CO.OH
Succinic acid.
CO(OH)-CO.OH
CH2-CO.OH
Malic acid.
CH(NH2)-C0.0H
CH2-CO.OH
Aspartic or amidosuccinic acid.
Asparagin is the monamide of aspartic or amidosuccinic acid ;
it is isomeric with the diamide of malic acid.
CHI(NH2)–CO.NI
¿II²_CO.OII
Asparagin.
CH.OH-CO.NH
CH2-CO.NII2
Malamide.
Asparagin, CH N2O3.-This body exists naturally in aspa-
ragus, black salsify, the roots of marsh-mallow, licorice wood,
and in the buds of cereals, peas, vetches, and beans before they
flower. To extract it from these vegetables, they are expressed
while fresh, and the juice is clarified and concentrated. The
asparagin is deposited in colorless crystals. It is only slightly
soluble in cold water and alcohol, but is more soluble in hot
water. It forms combinations with both bases and acids.
Y
47
554
ELEMENTS OF MODERN CHEMISTRY.
When boiled with these agents, it loses ammonia and is con-
verted into aspartic acid.
C¹H³N²O³ + H2O
Asparagin.
NH³
C⭑H'NO*
Aspartic acid.
Aspartic Acid, C'H'NO', forms rhombic crystals, slightly
soluble in cold, and more soluble in hot water. Like glycocol,
aspartic acid can form compounds with both acids and bases.
C4H606
TARTARIC ACID.
CO.OH-CH(OH)-CH(OH)-CO.OH
This important acid was discovered by Scheele in the tartar,
or argol, which is deposited in casks in which wine is kept.
It is prepared from purified tartar, called cream of tartar, which
is acid tartrate of potassium.
Preparation. The salt is dissolved in boiling water, and
chalk is added until all effervescence, due to the disengage-
ment of carbon dioxide, ceases. Insoluble calcium tartrate is
deposited, and potassium neutral tartrate remains in solution.
The calcium tartrate is collected on a filter, and the filtrate is
precipitated by calcium chloride. A new portion of insoluble
calcium tartrate is thus obtained, and is washed and united with
the first portion. This salt is then suspended in water and
exactly decomposed by dilute sulphuric acid; calcium sulphate
is precipitated, and separated by filtration, and the filtered.
liquid, when sufficiently concentrated and allowed to evaporate
n a warm place, deposits crystals of tartaric acid.
in
Properties. Tartaric acid crystallizes in large, oblique rhom-
bic prisms, which often present hemihedral facettes. They are
unaltered by the air, and dissolve in about half their weight
of cold water and still more abundantly in boiling water.
They dissolve also in alcohol, but not in ether.
The aqueous solution of tartaric acid turns the plane of
polarization to the right. It forms white precipitates in lime-
water and baryta-water, but an excess of the acid redissolves
these precipitates.
If an excess of tartaric acid be added to a solution of cupric
sulphate, the liquid may be saturated with potassium hydrate,
but no precipitation of cupric hydrate will take place. The
liquid will remain transparent and will assume a beautiful
dark-blue color; it is called cupro-potassic solution. In the
TARTARIC ACID.
555
same manner, ferric chloride, to which tartaric acid has been
added, is not precipitated by an excess of potassium hydrate.
When tartaric acid is fused with potassium hydrate, it is
decomposed into acetic and oxalic acids.
CHO C²H¹O² + C²H²O¹
Action of Heat on Tartaric Acid.—1. Tartaric acid fuses
between 170 and 180°, and when the action of the heat is not
prolonged, it is converted into an isomeric acid, called meta-
tartaric.
2. If the acid be maintained for some time in fusion, it
loses water and is converted into ditartaric acid.
2C4H6O6
C8H10011+ H2O
Ditartaric acid.
3. When 15 or 20 grammes of tartaric acid are suddenly
heated over a naked fire for four or five minutes, the mass
swells up and a deliquescent, yellow, spongy mass is obtained,
which constitutes what is called tartaric anhydride.
C+H6O6 C4H4O5+ H2O
Tartaric anhydride.
When heated for some time to 150° in a hot-air oven, tar-
taric anhydride becomes insoluble.
4. When tartaric acid is distilled by heating it gradually in
a retort to 300°, it is transformed into two pyrogenous acids,
pyruvic and pyrotartaric acids.
C4H606 = C³H+O3 + CO2 + H2O
2C+H6O6
Pyruvic acid.
CH*O* + 3CO2 + 2HẢO
Pyrotartaric acid.
It is seen that these acids, produced by the action of heat
on a complex organic acid, differ from the latter only by the
clements of water and carbon dioxide. Such is the law of
pyrogenous acids established by Pelouze.
When tartaric acid is heated to 170°, in sealed tubes, with
water, it undergoes a remarkable modification: it is converted
into paratartaric acid and inactive tartaric acid; the latter is so
named because it is without action on polarized light, and
cannot be broken up, as can paratartaric acid, into a dextrogy-
rate and a levogyrate acid (Jungfleisch).
Action of Nitric Acid upon Tartaric Acid.-Very con-
centrated nitric acid converts tartaric acid into nitrotartaric
556
ELEMENTS OF MODERN CHEMISTRY.
acid, C'H¹(NO²)²06 (Dessaignes). This body may be obtained
in crystals, but it is not stable. Its aqueous solution decom-
poses between 40 and 50°, with a brisk effervescence of carbon
dioxide, and formation of oxalic acid. When the decompo-
sition takes place below 36°, a peculiar, crystallizable acid is
formed, which Dessaignes has named tartronic acid. Its com-
position corresponds to the formula CHO CH²O³(OH)".
TARTRATES.
Tartaric acid is dibasic; it contains two hydrogen atoms
which are replaceable by an equivalent quantity of metal.
Neutral tartrates and acid tartrates are known.
H
C+H+06
H
Tartaric acid.
H
M'} C+H+06
}
Acid tartrates.
M'
M'
C+H+06, or R"C+II+Q6
Neutral tartrates.
Neutral tartrates are known in which one atom of metal is
replaced by a monatomic oxidized group, such as (SbO)',
(FeO)', (BOO)'.
K
H
}
CH*06 }
K
(Sb0)'
C+II+06
K
(Fe0)'
C4II406
K
(BOO)'
C4П406
Potassium
Tartar-emetic.
Ferro-potassium tartrate.
acid tartrate.
Boro-potassium
tartrate.
Potassium Acid Tartrate, or Cream of Tartar, KHC¹H¹O,
is prepared from the crude tartar of wine-casks by subjecting
that product to several crystallizations in boiling water. It
crystallizes in right rhombic prisms, very slightly soluble in
water. If a concentrated solution of tartaric acid be added
to a saturated solution of potassium chloride, a precipitate of
potassium acid-tartrate will be formed on agitating the liquid.
Potassium Neutral Tartrate, K2CH'O.-This salt is pre-
pared by neutralizing a boiling solution of cream of tartar
with potassium carbonate. The evaporated solution deposits.
on cooling oblique rhombic prisms, very soluble in water.
K
Na
Potassium and Sodium Tartrate, NC+II+06 + 411²0.—This
salt, which is much used in medicine, was discovered in 1672
by Seignette, a pharmacist of Rochelle; hence it is often called
Rochelle salt, or Seignette's salt. It is prepared by neutralizing
a boiling solution of cream of tartar with sodium carbonate, and
evaporating the solution. On cooling, the double tartrate is
deposited in large, beautiful crystals, eight-sided right rhombic
prisms.
ANTIMONIO-POTASSIUM TARTRATE.
557
ANTIMONIO-POTASSIUM TARTRATE, OR TARTAR-
EMETIC.
(SbO)/
К K} C+H+O6
This salt is prepared by boiling cream of tartar with water
and oxide of antimony, which dissolves abundantly in the
liquid. After filtration and cooling, the salt is deposited in
crystals which are purified by a second crystallization.
Tartar-emetic crystallizes in rhombic octahedra, and the crys-
tals, which contain one molecule of water of crystallization for
two molecules of salt, effloresce in dry air.
Its taste is astringent and nauseating. It dissolves in 14.5
parts of cold water and in about two parts of boiling water.
It is insoluble in alcohol.
When heated to 200° it loses the elements of water and is
converted into a double tartrate of antimony and potassium, in
which the trivalent antimony replaces 3 atoms of hydrogen in
the tartaric acid.
C*H*(SbO)'KO
C¹H²Sь"HKO° + H³O
When heated to redness in a small, covered crucible, tartar-
emetic leaves an alloy of potassium and antimony, disseminated
in a mass of charcoal. When this mass is exposed to moist
air, it suddenly takes fire and explodes, projecting brilliant
sparks.
The following are the characteristics of a solution of tartar-
emetic:
Hydrogen sulphide forms an orange precipitate of antimony
sulphide.
A few drops of hydrochloric acid cause the appearance of
a white precipitate of antimony oxychloride, which disappears
in an excess of acid.
Potassium hydrate produces a white precipitate of antimony
oxide, which redissolves in an excess of alkali.
A plate of tin immersed in a solution of emetic precipitates
metallic antimony as a black deposit.
Tartar-emetic is a much employed medicine. In large doses,
or smaller ones frequently repeated, it is an energetic poison.
Ferro-Potassium Tartrate.-This salt is prepared by dis-
solving ferric hydrate in cream of tartar, and evaporating the
47*
558
ELEMENTS OF MODERN CHEMISTRY.
solution. It forms brown, amorphous scales, very soluble in
water. It is used in medicine.
Boro-potassium Tartrate is formed when boric acid is dis-
solved in a boiling solution of cream of tartar. It is an amor-
phous salt, very soluble in water.
PARATARTARIC ACID.
C8H12012+ 2H2O
This acid, which is isomeric with tartaric acid, exists in cer-
tain tartars. It was discovered in 1822 by Kestner, and has
been studied by Berzelius and by Pasteur.
It crystallizes in transparent, dissymetric prisms, which efflo-
resce in the air, losing their water of crystallization. It dis-
solves in 5.7 parts of water at 15°. Its solution does not
change the plane of polarized light, but Pasteur has succeeded
in separating it into two other acids, both of which are optically
active. One of them turns the plane of polarization to the
right, and is ordinary tartaric acid; the other deflects it to the
left, and is levo-tartaric acid. These two acids, which are iso-
meric with each other, reproduce paratartaric acid when they
are mixed in equivalent proportions. It is somewhat remark-
able that the mixture of their solutions is attended by a
development of heat (Pasteur).
The solution of paratartaric acid precipitates solutions of
sulphate, nitrate, and chloride of calcium, a character which
tartaric acid does not possess.
Independently of dextro-tartaric acid, levo-tartaric acid, and
paratartaric acid, there is a fourth isomeride, which is inactive
tartaric acid. It exerts no action on polarized light, and cannot
be separated into two active acids (Pasteur).
Jungfleisch has shown that these various modifications of tar-
taric acid may be produced at will by the action of a tempera-
ture of about 170° on a solution of ordinary tartaric acid.
CITRIC ACID.
C6H8O7
This acid, discovered by Scheele in 1784, is largely diffused
throughout the vegetable kingdom. It exists in lemons, oranges,
limes, currants, raspberries, cherries, etc.
It may be advantageously prepared from lemon-juice, which
URIC ACID.
559
is allowed to stand until it begins to ferment, and is then filtered,
and saturated with chalk while boiling. The precipitate of
calcium citrate is washed with boiling water, and decomposed
by a slight excess of dilute sulphuric acid. The liquid sepa-
rated from the calcium sulphate yields crystals of citric acid
after concentration.
This acid forms large, colorless crystals, derived from a right
rhombic prism. It dissolves in three-fourths its weight of
cold and half its weight of boiling water.
When heated, it melts. At 175° it disengages water, and
is transformed into a pyrogenous acid, which is identical with
the aconitic acid that may be extracted from aconite.
C6H8O7
C6H6O6
Aconitic acid.
H2O
If the heat be increased, carbon dioxide is disengaged, inde-
pendently of some accessory products, and oily streaks appear
in the neck of the retort, and solidify to a crystalline mass.
This product is itaconic acid. A portion of the distilled
product remains liquid; it is the anhydride of a third pyroge-
nous acid, isomeric with the preceding, and called citraconic
acid.
C6H6O6
Aconitic acid.
C5H6O¹
CHO* + CO
Itaconic and
Citraconic acids.
C5H+O3 + H2O
Citraconic acid. Citraconic anhydride.
Fused potassium hydrate converts citric acid into oxalic and
acetic acids.
CH³O + H2O = C²H²O¹ + 2C²H¹O²
The solution of citric acid has an acid reaction and a very
sour taste. It does not precipitate lime-water in the cold, but
the solution becomes clouded after boiling.
Citric acid is tribasic.
Magnesium citrate, which is soluble, is employed in medi-
cine; it is a purgative, having a sweetish taste. Ferric citrate
also is used in medicine.
URIC ACID.
C5H4N403
This body is related to the complex organic acids which
have just been studied. Among the numerous products de-
560
ELEMENTS OF MODERN CHEMISTRY.
rived from its oxidation, we may mention oxalic acid, C²O²-
OH
OH
OH'
and an acid, CO³<OH' which has been called mesoxalic.
Uric acid itself seems to be related, according to Baeyer, to
tartronic acid,—one of the products of the transformation of
tartaric acid (page 556).
Uric acid was discovered by Scheele, and its numerous meta-
morphoses were the subject of a classic research by Liebig and
Wöhler, and have been more recently studied by Baeyer and
other chemists.
Preparation.-Uric acid may be extracted from the excre-
ments of serpents, from guano, and from certain urinary cal-
culi, which are almost entirely composed of it. These sub-
stances are reduced to a fine powder, boiled with potassium
carbonate and lime, and the solution filtered. The colored
solution of potassium urate is mixed with a solution of ammo-
nium chloride, which produces a white precipitate of ammonium
urate. This salt is well washed, and treated with hydrochloric
acid, which sets free uric acid.
Uric acid may be obtained from guano by boiling that sub-
stance with an aqueous solution of borax (borax 1, water 120).
The boiling solution is filtered, and after cooling is precipitated
by hydrochloric acid.
Properties. Pure uric acid is a light, white powder, which
has a crystalline aspect under the microscope. When slowly
separated from dilute solutions, it sometimes forms larger crys-
tals, containing 2 molecules of water of crystallization. It is
often deposited from urine in small rhomboidal tables of a
brownish-yellow color.
Uric acid is insoluble in alcohol and in ether. It requires
15,000 parts of cold water, or 1800 parts of boiling water,
for its solution. It dissolves in solutions of the alkalies, form-
ing neutral urates containing two atoms of the alkaline metal.
It is therefore a dibasic acid. When carbonic acid gas is
passed into a solution of a neutral urate, an acid urate, which
is almost insoluble, is precipitated.
Hydrochloric acid forms a thick, white, gelatinous precip-
itate of uric acid when added to the solution of a urate.
When uric acid is heated to 160 or 170° with an excess of
hydriodic acid, it absorbs water, and is decomposed into glyco-
col, carbonic acid gas, and ammonia (Strecker).
METAMORPHOSES OF URIC ACID.
561
C5H+N¹O³ + 5H20
Uric acid.
C²H³NO² + 3C0² + 3NH³
Glycocol.
If a small quantity of uric acid be gently heated with nitric
acid in a porcelain capsule, it is dissolved with a disengagement
of red vapors, and the solution, evaporated at a gentle heat,
leaves a residue which assumes a purple color on the addition
of a drop of ammonia.
This test is characteristic of uric acid, and permits the de-
tection of the least traces of that substance. The purple body
formed is called murexide.
METAMORPHOSES OF URIC ACID.
Alloxan, C¹H²N2O*.-This body is one of the products of
the oxidation of uric acid by nitric acid; urea is formed at the
same time.
CH+N+O3 + H2O + 0 CHỈN*O* + CH*NO
Uric acid.
Alloxan.
Urea.
It may be prepared by introducing uric acid, in successive
small quantities, into nitric acid of a density of 1.41–1.42, as
long as it dissolves producing red vapors. The alloxan finally
separates in a mass of delicate needles; in about twenty-four
hours they are drained and dissolved in water at 60 or 65°.
On cooling, the alloxan separates in voluminous crystals con-
taining 4 molecules of water of crystallization. They efflo-
resce in dry air.
When crystallized from a hot solution, alloxan forms rhombic
octahedra, containing but a single molecule of water.
It is very soluble in water, and the solution is acid. By the
action of alkalies, baryta-water for example, alloxan is con-
verted into alloxanic acid, which is formed by the direct com-
bination of the elements of one molecule of water with alloxan.
C¹H²N²O¹ + H³O = C'H*N2O5
Alloxan.
Alloxanic acid.
The alloxanates are decomposed by boiling into mesoxalic
acid and urea.
C*H*N2O5 + H2O
Alloxanic acid.
Mesoxalic acid, C³O³(OH)²
C305H2 + CH'N2O
Urea.
Mesoxalic acid.
CO.OH-CO-CO.OH, is a
dibasic acid. According to Baeyer, its diatomic radical, mes-
Y*
562
ELEMENTS OF MODERN CHEMISTRY.
oxalyl, exists in alloxan itself, which is mesoxalylurea, that
is, urea in which two atoms of hydrogen are replaced by the
diatomic radical (C³O³)".
(CO)"
H2 N2
H2
Urea.
(CO)"
(C303) N2
H2
Mesoxalylurea
(alloxan).
Parabanic Acid, C³H²N²O³.—This body is formed by the
action of an excess of nitric acid on alloxan, which thus gives
up the elements of carbon dioxide.
CH?NO* + 0
Alloxan.
CO² + C³H2N2O³
Parabanic acid.
Parabanic acid forms thin, transparent prisms, which are
very soluble in water. By boiling with acids, it is transformed
into oxalic acid and urea. Baeyer regards it as oxalylurea.
(CO)"
(C202)'' N2
H2
When parabanic acid is heated with ammonia, ammonium
oxalurate is formed, and separates in fine needles. In this
case the parabanic acid is converted into oxaluric acid by
directly combining with the elements of water.
C³H2N2O3 + H2O
Parabanic acid.
C3H4N2O*
Oxaluric acid.
It is seen that oxaluric acid is related to parabanic acid, as
alloxanic acid is to alloxan.
Alloxantin, CH'N'O'.-This body is produced by the re-
duction of alloxan. When a current of hydrogen sulphide is
passed through a cold solution of alloxan, sulphur separates,
and a crystalline precipitate of alloxantin soon forms.
2C¹H²N²O¹ + H2S =
Alloxan.
CH+NO+ H2O + S
Alloxantin.
Alloxantin is also formed directly, at the same time as
alloxan, by the action of weak nitric acid on uric acid. It
crystallizes in small, colorless prisms containing 3 molecules
of water of crystallization. It is but slightly soluble in cold
water. Nitric acid converts it into alloxan, and reducing agents
transform it into dialuric acid.
Dialuric Acid, C'H'N'O', is the product of the prolonged
METAMORPHOSES OF URIC ACID.
563
action of hydrogen sulphide on a hot solution of alloxan or
alloxantin.
CH²N²O¹ + H2S
Alloxan.
C*H*N²O* + S
Dialuric acid.
It is also formed by the action of sodium amalgam on the
same solutions.
It crystallizes in long needles, quite soluble in water; these
crystals assume a red color in the air, and are gradually trans-
formed into alloxantin.
When a solution of alloxan is added to a solution of dialuric
acid, alloxantin is formed.
C*H*N²O* + C¹H²N²O¹
Dialuric acid.
Alloxan.
C®H*N¹O² + H2O
Alloxantiu.
Baeyer regards dialuric acid as tartronyl-urea, that is, urea
in which two atoms of hydrogen are replaced by the diatomic
radical of tartronic acid, CHO³ (OH)² = CO.OH-CH(OH)-
CO.OH.
(CO)"
H2N2
H2
Urea.
(CO)"
(C3H203)'' N2
H2
Dialuric acid
(tartronyl-urea).
Purpuric Acid and Murexide.-Scheele had already ob-
served murexide, which Prout studied and described as pur-
purate of ammonia. It is, indeed, the ammonium salt of a
nitrogenized acid, CH³N³O°, for which it is convenient to pre-
serve the name purpuric acid (Beilstein).
Murexide is formed by the action of ammonia on dry allox-
antin heated to 100°, or again, when ammonia or ammonium
carbonate is added to a hot solution of alloxantin or alloxan.
CH⭑N'O' + 2NH³
Alloxantin.
CH*(NH4)NO + HẢO
Murexide (ammonium purpurate).
Murexide crystallizes in quadrangular prisms, or in tables
which are green by reflected and red by transmitted light.
These crystals, which contain one molecule of water, present
the magnificent metallic reflections shown by the wings of can-
tharides. They dissolve in water with a rich purple color.
Allantoin, C*H*N‘O³.—This body was discovered in 1800,
by Vauquelin and Buniva, in the allantoic liquid of the cow,
that is, the urine of the foetal calf. It occurs also in the urine
of young calves. In 1836, Liebig and Wöhler obtained it by
oxidizing uric acid with lead dioxide. Gorup-Besanez has
observed its formation in the action of ozone upon uric acid.
564
ELEMENTS OF MODERN CHEMISTRY.
Grimaux has recently made the synthesis of allantoin by
heating one part of glyoxylic acid with two parts of urea, for
eight or ten hours.
C2H2O2(CH'N'O) = CH°N¹O³ + 2H2O
Glyoxylic acid.
Urea.
Allantoiu.
From this remarkable synthesis, it appears that allantoin is
derived from two molecules of urea; it is the diureide of gly-
oxylic acid.
Allantoin may be prepared by boiling uric acid with water,
and adding lead dioxide, in small quantities, as long as that
oxide continues to be converted into a white powder, which is
lead carbonate. The filtered liquid, freed from lead by hydro-
gen sulphide, yields crystals of allantoin on evaporation.
CH¹N¹³ + H2O + 0 C*H°N*O* + CO
Uric acid.
Allantoin.
Allantoin crystallizes in brilliant, colorless prisms. It dis-
solves in 30 parts of boiling water and in 160 parts of cold
water; it is also soluble in alcohol, but is insoluble in ether.
It forms crystallizable compounds with certain metallic oxides.
We cannot further continue the study of the numerous de-
rivatives of uric acid. This study has already thrown great
light upon the constitution of the acid, which Baeyer regards
as derived from tartronic diamide, that is, the diamide corre-
sponding to tartronic acid.
C3H203
J OH
{
он
Tartronic acid.
C3H203
{
J NH2
NH2
Tartronic diamide.
C³11203 NH.CN
S NH.CN
Tartronic dicyanamide
(uric acid).
Grimaux has recently made the synthesis of alloxan; all
of the members of the uric series can thus be obtained synthet-
ically, excepting uric acid itself.
ALCOHOLS OF HIGHER ATOMICITY.
One tetratomic alcohol is known with certainty. It is ery-
thrite, of which de Luynes recognized the true nature.
Glucose, which Berthelot regarded as a hexatomic alcohol,
seems to fill a mixed function: it is at the same time an alde-
hyde and a pentatomic alcohol.
ERYTHRITE.
565
The best characterized hexatomic alcohol is mannite, a sweet,
crystallizable substance, which is extracted from manna. Glu-
cose is related to manna, from which it differs only by two
atoms of hydrogen. The constitution of mannite may be ex-
pressed by the following formula:
C6H1406 CH8vi(OH)6
It results from the experiments of Linnemann that various
saccharine matters, possessing the composition CH12O6, fix H2
directly under the influence of sodium amalgam and water, and
are converted into mannite. The latter body is characterized
as a hexatomic alcohol by the property which it possesses of
forming neutral compounds with 6 molecules of a monobasic
acid, such as acetic acid. In other words, this body contains
6 hydroxyl groups, or six atoms of hydrogen capable of being
replaced by 6 monobasic acid radicals.
ERYTHRITE.
C+1I100+ = C+H°(OH)*
This beautiful body was discovered in 1849 by Stenhouse,
who found it among the decomposition products of erythric
acid or erythrin, a substance contained in certain lichens. In
1852, Lamy obtained from an algæ, the Protococcus vulgaris,
a substance which he first named phycite, but which he after-
wards recognized to be identical with erythrite.
Preparation. De Luynes first extracts erythrin from a
lichen, the Rocella Montagnei, and decomposes it, while still
moist, by slaked lime in closed vessels at a temperature of
150°. Under these conditions, erythrin is decomposed into
carbonic acid which is at once taken up by the lime, orein, and
erythrite, which are separated by crystallization, the orcin being.
deposited first. The erythrite is purified by washing it with
ether, which removes a trace of orcin.
Properties. Erythrite crystallizes in right square prisms.
The crystals are hard, have a feeble, sweet taste, and are very
soluble in water, soluble in boiling absolute alcohol, and insol-
uble in ether. They melt at 130°. Erythrite reacts with the
acids, forming neutral bodies analogous to the ethers (Berthelot).
When heated with a concentrated solution of hydriodic acid,
it is converted into secondary butyl iodide (de Luynes).
C¹H³I + 4H²0 + 31²
C*H*O* + THI
Erythrite.
Secondary butyl iodide.
48
566
ELEMENTS OF MODERN CHEMISTRY.
MANNITE.
C6H1406
C6H8(OH)6
This body, discovered by Prout in 1806, exists in a great
number of vegetables. It is the most abundant constituent of
manna, a substance which flows from several species of ash,
either naturally or from incisions. It is prepared by dis-
solving manna in distilled water, in which the white of an egg
has previously been beaten up. The solution is boiled several
minutes and then filtered through a woollen cloth and allowed
to cool. The liquid then solidifies to a mass of crystals which
are purified by recrystallization after treatment with animal
charcoal.
Mannite forms large, right rhombic prisms. Its taste is
sweet, and it is soluble in water and alcohol.
When heated with a concentrated solution of hydriodic acid,
it is reduced to a secondary hexyl iodide.
CH¹¹О6 + 11HI
Mannite.
C6H¹³I+6H2O + 512
B-secondary hexyl iodide.
Berthelot has described a secondary hexa-stearic mannite,
containing CH8( C18H35 O²)6.
•
But, by the action of many acids upon mannite, compounds
are obtained which are not ethers of mannite, strictly speak-
ing, but of an anhydride of that body, to which Berthelot has
give the name mannitan.
C6H1406
Mannite.
C6H12O5
H2O
Mannitan.
Mannitan is isomeric with two sweet substances, quercite, or
the sugar of the glands, which was discovered in the glands by
Braconnot, and pinite, which has been extracted by Berthelot
from the resin of the California pine.
Dulcite, CH4O6, which has been obtained from Madagascar
manna, exists in certain plants, such as the Melampyrum
nemorosum, the Scrophularia nodosa, the Rhinanthus crista-
galli, and the Euonymus europæus. It forms large, oblique
rhombic prisms, and is less soluble in water than mannite; it
is but slightly soluble in alcohol. It melts at 188.5°. It dis-
solves in the hydracids without producing heat. Like its
SUGARS AND STARCHES.
567
isomeride, manna, it is reduced by hydriodic acid to a second-
ary hexyl iodide (G. Bouchardat).
Sorbite, CH4O6, recently obtained by J. Boussingault from
the fermented juice of the mountain-ash, is another isomeride
of mannite.
SUGARS AND STARCHES.
Among the more widely distributed products of the vege-
table kingdom must be included the various kinds of sugar,
starch, the gums, and the matter of young vegetable cells, or
cellulose.
These compounds contain carbon, hydrogen, and oxygen in
such proportions that the oxygen is present in exactly sufficient
quantity to form water with the hydrogen. Their composition
is then expressed by the general formula Cm (H2O)". If all of
the oxygen and hydrogen were removed in the form of water,
only carbon would remain. Hence the name hydrates of car-
bon, often applied to this class of bodies.
Some of them contain 6, and the others 12 atoms of carbon,
and they can be arranged in three different classes, of which
the types are glucose, saccharose, and starch.
Glucose, or grape-sugar, contains C6H12O6.
Saccharose, or cane-sugar, contains C12H22O¹¹.
{
Among the important sugars of this type, we may mention
lactose, or milk-sugar.
Starch, or amylaceous matter, has a composition expressed
by the formula C6H10O5. Its most important isomerides are
dextrin, inulin, the gums, and cellulose.
All of these bodies have the power of rotating the plane of
polarized light, either to the right or to the left.
They react with several molecules of an acid, forming neu-
tral compounds, a property which characterizes them as poly-
atomic alcohols (Berthelot).
GLUCOSE.
C6H12O6
This important body, which forms the solid and crystalliza-
ble part of honey, exists in a great number of dried fruits, on
the surface of which it forms a well-known white efflorescence.
568
ELEMENTS OF MODERN CHEMISTRY.
It is also found in the urine in the disease known as diabetes.
It may be made artificially by the action of dilute sulphuric
acid on starch (Kirchhoff), or on cellulose (Braconnot).
Preparation. Glucose is prepared in the arts by the fol-
lowing process:
6000 litres of water and 42 kilogrammes of sulphuric acid
are introduced into a large wooden trough, and the liquid is
heated by jets of superheated steam. When it is in full ebul-
lition, 2000 kilogrammes of starch suspended in 2000 litres
of warm water are allowed to run in gradually, and in thirty
or forty minutes the saccharification is complete. The sul-
phuric acid is then saturated with pulverized chalk, the insol-
uble calcium sulphate is separated, and the liquid concentrated
in boilers heated by steam until it marks 40 or 41° Baumé.
It is then allowed to crystallize, and solidifies to an opaque,
yellowish, crystalline mass, which is glucose.
The sulphuric acid has recently been replaced by hydrochlo-
ric acid, which produces a whiter product. The small quantity
of calcium chloride formed does not prevent the crystallization
of the glucose.
Properties. This body crystallizes in small, white, rounded
masses, agglomerated like cauliflowers. The crystals contain
one molecule of water of crystallization (CHO+ H2O).
They remain unchanged in the air. They melt when heated
on a water-bath, and lose their water at 100'. Anhydrous
glucose melts at 144°.
Glucose dissolves in a little more than its own weight of
water at 17°. It is three times less soluble than cane-sugar,
and in solutions of equal concentration it is three times less
It is much less soluble in alcohol than in water.
The solution of glucose rotates the plane of polarization to
the right ([] D 56.4°).
sweet.
When glucose is heated to 170°, it loses the elements of
water and is converted into a colorless mass, not very sweet,
which has received the name glucosan.
C6H12O6
Glucose.
10.
C6H1005
+ H2O
Glucosan.
Glucose forms true compounds with the bases. There is a
glucosate of calcium, C6H¹ºCa″O + H2O. It is precipitated
when alcohol is added to a solution of calcium hydrate in glu-
cose.
GLUCOSE.
569
These compounds are not stable.
If potassium hydrate be added to a solution of glucose and
the liquid be heated, it first becomes yellow, and then rapidly
assumes a deep-brown color. The same color is produced when
glucose is heated with calcium or barium hydrate.
According to Peligot, there are formed under these circum-
stances two acids, which he named glucic and melassic acids.
Ordinary or cane-sugar does not produce this reaction, and can
thus be distinguished from glucose.
Glucose reduces various metallic solutions. If a solution of
cupric sulphate be poured into a solution of glucose, and potas-
sium hydrate be added, no precipitate is formed, but the liquid
acquires a dark-blue color. On heating it, a yellowish precip-
itate of cuprous hydrate is formed.
This reaction, which was discovered by Troemmer, is very
sensitive, and can be used for the detection of the smallest
quantities of glucose. In making the test, a cupro-alkaline
solution is employed, made by dissolving cupric tartrate in
potassium hydrate (Barreswill's solution), or by adding sodium
and potassium tartrate and caustic soda to a solution of cupric
sulphate (Fehling's solution).
When a solution of glucose is heated with bismuth nitrate
and an excess of potassium hydrate, a black precipitate of
reduced metallic bismuth is formed.
When a solution of common salt is added to a solution of
glucose and the liquid is allowed to evaporate spontaneously,
crystals are deposited which constitute a definite compound
of the two bodies. They contain 2(NaCl + 2C6H12O6) +
3H20.
Glucose forms combinations with the acids, like mannite, and
these combinations represent glucose in which a certain num-
ber of hydrogen atoms are replaced by acid radicals. Ber-
thelot had regarded glucose as a hexatomic alcohol, containing
6 hydroxyl groups, but Colley has shown that it is a penta-
tomic alcohol. He has described a compound produced by the
action of acetyl chloride on glucose, and which he names aceto-
chlorhydrose. It contains
C6HTO { (C²H³O²) +
On account of the reducing properties of glucose, it may
be considered that the oxygen atom of the group CH'O forms
48*
570
ELEMENTS OF MODERN CHEMISTRY,
part of an aldehyde group CHO. Hence glucose is at the
same time an aldehyde and a pentatomic alcohol, and its
constitution would be represented by the formula CH2.OH-
CH.OH-CH.OH-CH.OH-CH.OH-CHO.
The following fact supports this view. When chlorine gas
is passed into a solution of glucose, the latter is converted into
an acid, gluconic acid, C6H12O7, which only differs from glucose
by containing one more atom of oxygen. This acid corre-
sponds to gluconic aldehyde, and the following formulæ indi-
cate the relations existing between the bodies just mentioned:
CH2.OH
(CH.OH)+
сно
Glucose.
CH2.CI
(CH.OC²H³0)
сно
Acetochlorhydrose.
CH2.OH
(CH.OH)+
CO.OH
Gluconic acid.
LEVULOSE, OR UNCRYSTALLIZABLE FRUIT-
SUGAR.
C6H12O6
Independently of the glucose which effloresces on their
surface after desiccation, many fruits contain another sugar,
incapable of crystallization, and which strongly deviates the
plane of polarization to the left. It is levulose.
Levulose exists in inverted sugar (page 574). Many sweet
fruits contain inverted sugar; among them are grapes, cherries,
figs, gooseberries, etc.
It may be extracted from inverted sugar (a mixture of equal
proportions of glucose and levulose). Dubrunfaut recommends
the following process: 10 grammes of inverted sugar, 6 grammes
of slaked lime, and 100 grammes of water are intimately mixed.
The mass, which is at first liquid, becomes pasty on agitation,
and then contains a solution of calcium glucosate and solid cal-
cium levulosate. It is strongly pressed in a cloth and the
compound of levulose and lime is decomposed by oxalic acid.
The levulose remains in solution, and after evaporation forms
an uncrystallizable syrup which is much sweeter than a solu-
|tion of glucose.
Levulose is directly fermentable. When heated to 170°, it
loses the elements of water and is converted into levulosan.
C6H12O6 C6H1005+ H2O
Levulosan.
SACCHAROSE.
571
Other sugars are known which may be classed with glucose.
Such are the following:
1. Sorbin, CHO", a substance which crystallizes in large,
transparent rhombohedra; has been obtained from the berries
of the mountain-ash by Pelouze.
2. Inosite, CH¹²О6 + H²О, a sugary matter extracted by
Scherer in 1850 from the muscles, and which has since been
found in the lungs, kidneys, spleen, and liver (Cloëtta). In-
osite is identical with a substance that Vohl extracted from
green beans, and to which he gave the name phaseomannite.
Inosite forms large, rhombic tables, or transparent, colorless
prisms, having a sweet taste. The crystals effloresce in the air.
They are soluble in water, but insoluble in absolute alcohol and
in ether. The aqueous solution is optically inactive; it is not
converted into glucose by the action of dilute acids; it does
not reduce cupro-potassic solutions, nor will it ferment under
the influence of yeast.
SACCHAROSE, OR CANE-SUGAR.
C12H22O11
Extraction.-Ordinary sugar, which is universally diffused in
the vegetable kingdom, is extracted principally from sugar-cane,
sugar-maple, and beet-root. Fresh sugar-cane contains about
eighteen per cent. of sugar: beet-root contains only about ten
per cent. (Peligot).
Certain sweet fruits contain cane-sugar, independently of
inverted sugar.
According to Buignet, such are apricots,
peaches, pine-apples, lemons, plums, and raspberries.
We can only briefly indicate the processes which are em-
ployed for the extraction of sugar from beet-root.
The roots are washed, and reduced to pulp in a machine
provided with a cylinder armed with teeth and having a rapid
rotary motion. This pulp is then strongly pressed in woollen
sacks by means of a hydraulic press, and the juice is imme-
diately transferred to large boilers having double bottoms and
heated by steam, and milk of lime is added.
This operation, which is called defecation, is intended not
only to separate certain substances which form insoluble com-
pounds with the lime, but to prevent the juice from becoming
altered by reason of its acidity. As the sugar itself dissolves
a large quantity of lime, the latter must be got rid of. A cur-
572
ELEMENTS OF MODERN CHEMISTRY.
rent of carbon dioxide is consequently passed into the solution,
and decomposes the saccharate of calcium. Another process
of déchaulage, recently devised, depends on the employment.
of ammonium phosphate. Insoluble calcium phosphate is
formed, and the ammonia is disengaged on account of the high
temperature at which the operation is conducted. By this
process the neutralization is more perfect.
The liquid is then heated to about 95°, and filtered through
a layer of animal charcoal in grains; it is then concentrated in
evaporating-pans heated by steam. When the syrup marks
25° Baumé, it is again filtered through animal charcoal, and
the concentration is finished in pans heated by steam, and in
which a vacuum is maintained during the evaporation. The
cooking of the syrup is thus carried on at a temperature not
above 75 or 80°, and these conditions assure a fine quality of
product and a good yield by preventing as much as possible
the transformation of the sugar into uncrystallizable sugar.
When the syrup marks 42 or 43°, it is run into cooling-
pans, where it is continually stirred until the sugar is depos-
ited in small crystals. These are distributed in moulds, which
consist of terra-cotta cones having a hole in the summit, which
for the time is closed. These cones are placed in an oven
heated to 25°, where the crystallization takes place; when the
syrup has solidified, the holes in the cones are opened and the
thick and colored mother-liquor is allowed to drain out; it con-
stitutes molasses. The loaves of sugar, drained and dried, are
delivered to commerce as crude or brown sugar.
For some years an apparatus has been used for draining
and bleaching of crude sugars, which consists of a cylindrical
cage having perforated metallic walls. It is put into rapid
motion on its axis, and the molasses is expelled through the
perforated walls by centrifugal force. The apparatus is called
the centrifugal drier.
5
Refining of Crude Sugar. The crude sugar is crushed,
sifted, and dissolved in about 30 per cent. its weight of water,
the operation being conducted in a boiler heated by steam.
per cent. of animal charcoal is then thrown into the hot solu-
tion, and, after stirring, per cent. of beef's blood is added.
The latter coagulates in the liquid and envelops all of the sus-
pended particles, uniting them in a scum which is easily re-
moved. When the liquid becomes clear, it is drawn off and
filtered. It is then passed through grained animal charcoal,
SACCHAROSE.
573
which completely decolorizes it. It is concentrated in vacuum-
pans, from which it is drawn into a large copper vessel having
a double bottom. It is continually stirred until crystallization
commences, after which it is run into moulds, which are then
placed in rooms heated to 20°. After the crystallization is
completed, the syrup remaining liquid is allowed to drain out.
At the termination of the draining, a creamy mixture of
white clay and water is poured on the surface of the sugar in
each mould, and the water of this broth slowly penetrates the
mass of sugar, liquefies the syrup which remains between the
crystals, and carries it to the lower part of the mass.
The clay,
having lost its water, contracts, dries up, and remains
decolorized sugar as a dry cake. It is removed, and a syrup
of white sugar is run into the whitened and porous loaf and
fills up all of the spaces when it solidifies in the oven.
upon the
This operation, the object of which is the decolorizing of
the sugar-loaves, is called claying. The clay broth may be
replaced by syrup of white sugar, an operation which is called
decoloring.
The sugar solidified in the moulds is a compact, crystalline,
white mass, composed of little grains. It may be obtained in
voluminous crystals by concentrating the syrup until it marks
37° Baumé, and then exposing it for some days to a tempera-
ture of 30° in copper vessels, across which threads are stretched.
The sugar is deposited on the threads in large crystals known
as rock-candy.
Properties of Sugar.-Sugar crystallizes in large, oblique
rhombic prisms, having hemihedral facettes. The crystals are
hard, anhydrous, and unalterable in the air. It dissolves in
one-third its weight of cold water; the solution is thick, and is
known as simple syrup. Sugar is insoluble in ether and in
cold absolute alcohol. Boiling absolute alcohol dissolves a little
more than one per cent.; ordinary alcohol will take up more.
The aqueous solution of sugar deviates the plane of polari-
zation to the right, ([a]D= +67°).
At 160°, sugar melts to a thick, transparent liquid, which
solidifies to an amorphous, vitreous mass on cooling.
When maintained for a long time at a temperature of 160
or 161°, it breaks up into glucose and levulosan (Gélis).
C12H22O11
Saccharose.
C6H12O6 +
Glucose.
C6H1005
Levulosan,
Between 190 and 200° it loses the elements of water and is
574
ELEMENTS OF MODERN CHEMISTRY.
converted into a bitter, brown, amorphous mass, which is desig-
nated as caramel.
Inverted Sugar.-By the action of dilute acids, sugar is
converted, slowly in the cold and rapidly on boiling, into a
mixture, in equal proportions, of two isomeric sugars which
have opposite rotatory powers: they are glucose and levulose.
The mixture is called inverted sugar.
C12H22O11
Saccharose.
+ H2O
C6H12O6 + CH¹²O6
Glucose.
Levulose.
The same transformation is effected by the soluble matter
of yeast (Berthelot), and also, according to Buignet, by the
action of the peculiar ferments which exist in most fruits.
Sugar only ferments after having first undergone this trans-
formation into inverted sugar by the action of the ferment.
Nitric acid converts sugar into saccharic acid, CH¹ºOº, and
oxalic acid.
Concentrated sulphuric acid carbonizes it.
Saccharose resists the action of alkalies better than glucose.
It forms with them and with the bases in general, definite com-
binations known as saccharates.
If a mixture of sugar and slaked lime be triturated with
water and the whole be thrown upon a filter, the liquid which
passes through will be colorless and strongly alkaline. When
it is heated to ebullition, it changes into a solid mass which
again becomes liquid on cooling. It is a solution of saccharate
of calcium.
An analogous experiment may be made with a concentrated
boiling solution of barium hydrate.
When sugar
is heated to 150 or 160° with barium hydrate,
it yields lactic acid. When fused with potassium hydrate, it
disengages hydrogen, and carbonate, oxalate, formate, acetate,
and propionate of potassium are formed.
Sugar forms a combination with sodium chloride, consisting
of deliquescent crystals which contain C2H2O.NaCl.
LACTOSE, OR MILK-SUGAR.
C12H22O11 + H2O
This sugar exists in solution in the milk of mammals, and is
extracted from the whey which remains after the manufacture
of cheese. It is only necessary to evaporate this liquid to
crystallization.
MALTOSE.
575
Milk-sugar occurs in commerce in cylindrical masses, formed
of an agglomeration of crystals around a little stick which.
serves as a nucleus. The crystals are colorless, hard, and creak
when crushed by the teeth. They are right rhombic prisms,
terminated by octahedral points. They contain one molecule
of water of crystallization which they lose at about 140°.
They dissolve in 6 parts of cold, and in 2 parts of boiling
water. The solution turns the plane of polarization to the
right.
When heated with nitric acid, lactose yields certain acids,
among which is one which is but slightly soluble in water, and
which is called mucic acid. It contains CH¹008, and is iso-
meric with saccharic acid, which is also produced by the oxi-
dation of lactose by nitric acid. Liebig found tartaric acid
among the products of this oxidation, and a small quantity of
paratartaric acid has also been observed to be formed (Carlet).
Lastly, oxalic acid is also produced.
When boiled with dilute sulphuric acid, milk-sugar is con-
verted into glucose and another sugar isomeric with glucose,
and to which the name galactose has been given. Galactose
will undergo the alcoholic fermentation under the influence of
yeast. It is crystallizable, and occurs in microscopic crystals
united together in tufts.
Milk-sugar reduces cupro-alkaline solutions.
When exposed to the air at summer heat, a solution of lac-
tose in presence of an alkaline salt or calcium carbonate soon
undergoes the lactic fermentation (page 577).
MALTOSE.
C12H22O11 + H2O
This name is given to the crystallizable sugar produced by
the action of diastase on starch. It may be prepared by digest-
ing starch paste at 60° with a solution of diastase. The solu-
tion is precipitated by alcohol, filtered, the alcoholic liquid
evaporated to a syrupy consistence, more alcohol added, and
the solution set aside to crystallize in a bell-jar over sulphuric
acid.
Maltose forms a crystalline mass, composed of hard, white
needles. It loses its water of crystallization at 100°. Its solu-
tion turns the plane of polarization to the right, [a]D=+
576
ELEMENTS OF MODERN CHEMISTRY.
149.5°. It reduces cupro-potassic solutions, and when boiled
with dilute acids is converted into glucose.
FERMENTATION.
If yeast be introduced into a tolerably concentrated solution
of glucose, and the liquid be exposed to a temperature between
20 and 30°, bubbles of an incombustible gas will soon be dis-
engaged, and this gas will produce a cloud in lime-water. It
is carbon dioxide.
After the disengagement of gas has ceased, a small quantity
of alcohol may be obtained by distilling the liquid.
In this experiment, the glucose disappears; it is broken up
into alcohol and carbon dioxide. The decomposition is effected
by yeast, and is called fermentation. The sugar is the fer-
mentable substance; the yeast is the ferment.
The ferment is an organized matter which develops and mul-
tiplies at the expense of the glucose. The latter, is directly at-
tacked by this being which lives at its expense, and undergoes a
complete decomposition, of which carbon dioxide and alcohol
are the principal products. The ferment plays an active part,
which was first suspected by Cagniard-Latour and Schwann,
and demonstrated by Pasteur.
Alcoholic Fermentation.-The decomposition of glucose.
under the influence of yeast constitutes the alcoholic fermenta-
tion.
It is expressed in the following equation:
C16H12O6
Glucose.
2C2H6O + 200²
Alcohol.
It is shown by the experiments of Pasteur, that only 94 per
cent. of the quantity of glucose decomposed undergoes the
change indicated by the above formula. The remaining 6 per
cent. are employed: 1, in the formation of small quantities of
succinic acid and glycerin; 2, in the development of new yeast.
cells.
1
100
Yeast is composed of a mass of cells or ovoid corpuscles,
having a diameter of of a millimetre, and arranged in
clusters (Fig. 125). Their walls are an elastic membrane,
and their contents are liquid or granular. They contain cellu-
lose, albuminoid matter, and mineral salts. When they are
FERMENTATION.
577
introduced into a substance which contains the materials neces-
sary for their development, they multiply rapidly. Pasteur has
made decisive experiments on this point. He planted some
yeast cells in a solution of sugar to which he had added a small
quantity of an ammoniacal salt and some phosphates. The solu-
tion of sugar fermented, and the ferment developed by budding,
the new cells absorbing the
ammonia and the phosphates.
They obtained from the sugar
the matter necessary to form
cellulose, and from the ammo-
nia the nitrogen required for
the elaboration of the albumi-
noid matters. However, these
artificial conditions are
are not
those which are best adapted
for the propagation of the cells.
The latter increase with ex-
treme energy in liquids which
contain, besides the yeast, glu-
cose, and a small quantity of
albuminoid matter ready formed.

FIG. 125.
Lactic Fermentation. This fermentation, of which the
conditions have already been indicated (page 540), is accom-
plished by the action of a peculiar ferment of vegetable char-
acter. It is formed of small round or elongated cells, very
short, and isolated, or in masses. They are much smaller than
yeast cells, and constitute the lactic yeast of Pasteur. It only
acts upon glucose or lactose in a neutral or alkaline liquid.
Hence the necessity of adding sodium carbonate or chalk to
the liquid. The reaction consists of a splitting of the glucose
molecule.
C6H12O6
Glucose.
203H603
Lactic acid.
Butyric Fermentation. This consists in the transformation
of calcium lactate into butyrate,-a transformation that is ac-
companied by a disengagement of hydrogen. According to
Pasteur, this fermentation is caused by infusoria, and the ani-
malculæ live and are developed in situations where they are
deprived of free oxygen. Such is the energy of their respira-
tory functions that free oxygen kills them (Pasteur). They
.
Ꮓ
49
578
ELEMENTS OF MODERN CHEMISTRY.
respire by decomposing oxidized bodies and assimilating the
oxygen.
We have already considered the acetic fermentation. We
may add that by the action of a peculiar ferment, glucose is
converted into mannite and a gummy matter, very soluble in
water, and which gives a viscous consistence to the fermented
liquid. This is called the viscous fermentation.
FERMENTED BEVERAGES.-The foregoing summary indi-
cations regarding fermentation may be completed by some
general notions upon the fermented beverages, particularly
wine and beer.
Wine. It is universally known that wine is the product of
the fermentation of grape-juice. This juice contains in solu-
tion inverted sugar, a small trace of gummy matters, vegetable
albumen, a trace of fatty matters, coloring matters, free tar-
taric and malic acids, and various tartrates, principally potas-
sium acid-tartrate, or cream of tartar.
The clarified wine which results from the fermentation of
this juice contains, independently of water, various products,
some of which existed in the juice, and others which are the
results of the transformation through which it has passed.
Among the first are the mineral and vegetable salts of the juice
(in smaller proportion, because they are partly deposited with
the lees), the gummy matter, a small quantity of fatty and
albuminoid substances, the coloring matters, free tartaric and
malic acids, and the tannin derived from the grape-stems and
from the skins and seeds. Among the substances which result
from the fermentation are:
1. Alcohol, which is the principal product.
2. Carbonic acid gas; it is well known that it exists abun-
dantly in champagnes.
3. Small quantities of aldehyde and acetic acid produced by
oxidation of the alcohol. The acetic acid reacts upon the
alcohol contained in the wine, forming acetic ether.
4. Glycerin and succinic acid, in small quantities (Pasteur).
5. Traces of compound ethers, which contribute to the bouquet
of the wine. Besides acetic ether, traces of a compound ether
called œnanthic ether have been found in wine; it appears to
be pelargonic ether, CH¹O²(C2H5). Berthelot states the exist-
ence of but slightly volatile acid ethers (malic, tartaric) in wine.
The following table indicates the quantities by volume of
pure alcohol contained in 100 volumes of various wines:
FERMENTATION.
579
Madeira
Port
Roussillon .
Hermitage (white)
Malaga
Saint-Georges
Sauterne (white)
Cyprus
Lunel
•
•
•
Graves
Frontignan
Champagne
Rhine
20.48
20.22
16.67
•
16.03
•
•
15.87
15.00
15.00
15.00
•
14.27
12.30
11.76
11.60
11.11
11.00
7.5 to 8
7.66
7.66
7.83
Strongest Bordeaux
Lightest
Red Bourgogne
Red Mâcon
Red Chablis
•
Beer.-Beer is a fermented beverage, made from a wort of
germinated barley, and ordinarily rendered aromatic by hops.
Like all other cereals, barley contains a considerable proportion
of starch. During the germination, this starch is partially con-
verted into maltose by the action of a nitrogenized matter,
which is formed in the sprouting grains, and which is called
diastase. In order to saccharify the barley, it is then first
necessary to cause it to germinate, and for this purpose it is
moistened with water, and kept for some time at
a temperature of 14 or 15°; the object of this
operation, called malting, is the development of
the diastase necessary for the saccharification
of the starchy matter. When the sprout has
acquired about the same length as the grain
(Fig. 126), the germination is arrested by ex-
posing the malt to the action of a temperature
of about 50°. The dry malt is then reduced
to a coarse powder, placed in a large vat, and
brewed for about three hours with water heated
to 50 or 60°. In this operation, the diastase of the malt con-
verts the starch into dextrin and maltose, which dissolve, to-
gether with the other soluble principles of the grain.

FIG. 126.
The sweet wort thus obtained is heated with hops, which
yield to it their essential aromatic oil. It is then properly
cooled and allowed to ferment in deep vats, into which a cer-
tain quantity of yeast produced in a previous operation is in-
troduced at the same time. The alcoholic fermentation soon
begins and goes on with great activity during a few days. As
580
ELEMENTS OF MODERN CHEMISTRY.
soon as it has ceased, the liquid can be delivered for consump-
tion. The quality of beer is better when the fermentation
takes place at a low temperature.
Beer contains much water, free carbonic acid gas, alcohol (2
to 5 per cent.), variable quantities of saccharine matters, dex-
trin, nitrogenized matters, extractive, bitter, and coloring mat-
ters, essential oil, and various salts.
STARCH.
C6H1005
Starch is universally diffused throughout the vegetable king-
dom. It is especially abundant in the seeds of leguminous
plants and cereals, and in the potato.
Extraction. To extract starch from potatoes, they are re-
duced to pulp by means of a rasp, and the pulp is placed in a
sieve and washed by a stream of water. The water carries
with it the fine granules of starch, while the torn cells of the
potato remain in the sieve. The starch gradually deposits
from the water, and collects in the bottom of the vessel, where
it settles, forming a cake from which the supernatent water
may be separated by decantation.
Starch may be extracted from wheat by making a paste of
flour and kneeding it in a sieve under a jet of water: the starch
granules are carried with the water, and a soft, gray, elastic
mass remains in the sieve, constituting the nitrogenized matter
of the flour, or gluten.
Another process, almost abandoned at present on account of
its offensiveness, consists in allowing the coarsely-ground grain.
to putrefy. Putrefaction destroys the gluten, while the starch
resists decomposition.
Physical Properties.-Starch is a white powder, formed of
granules which present an organic structure. Their size and
shape are variable (Fig. 127), their diameter being from 2 to 185
thousandths of a millimetre. Those of potato starch are larger
than those of starch from grain. These granules are made up
of concentric layers, which are more dense as they are nearer
the surface. It is easy to make this structure apparent by
causing the granules to undergo a partial disintegration by the
action of hot water. Thy swell up, burst open, and separate
into thin layers, as shown in Fig. 128.
STARCH.
581
Chemical Properties.-Starch is insoluble in water, alcohol,
and ether. Contact with water heated to 60 or 70° causes
to swell up considerably, without dissolving. A semi-trans-
parent, gelatinous mass results, which is known as starch paste.
When starch is boiled with a large quantity of water and the
whole is thrown on a filter, the liquid which passes is slightly
turbid, and constitutes what is known as solution of starch.
It contains in suspension flakes of amylaceous matter small
enough to pass through the filter. It also contains a small
quantity of soluble starch (see farther on).
If a few drops of iodine be added to solution of starch, a
deep-blue color is at once produced. This blue color disappears
when the liquid is heated to 90°, and reappears on cooling. If
a few drops of a neutral solution of calcium chloride be added
to the liquid, dark-blue flakes are precipitated, constituting
what is called iodide of starch. It is starch dyed by iodine.


FIG. 127.
FIG. 128.
Metamorphoses of Starch-Dextrin.-When long heated
to 100° starch is converted into soluble starch, which yields a
blue color with iodine (Maschke).
Between 160 and 200° it is converted into a body which is
very soluble in water, and the solution of which is not colored
by iodine. This solution strongly turns the plane of polariza-
tion to the right; hence the name dextrin given to this body,
which is regarded as isomeric with starch, (CHO)". A very
concentrated solution of dextrin has the appearance of a solu-
tion of gum. It is used as a mucilage for labels, and for the
preparation of immovable surgical dressings.
Alcohol added to a solution of dextrin precipitates the latter
substance in the form of flakes. Subacetate of lead does not
49*
582
ELEMENTS OF MODERN CHEMISTRY.
precipitate dextrin, a character which permits the latter body
to be distinguished from gum arabic.
When starch is boiled with water containing a few per cent.
of sulphuric acid, it is first converted into dextrin, then into
glucose. It is generally considered that the dextrin is formed
by a simple molecular transformation of the elements of the
starch, and that the glucose is then produced by the simple.
fixation of one molecule of water.
C6H1005+ H2O
Starch.
C6H12O6
Glucose.
According to Musculus, this is not the case; but soluble
starch is the result of a metameric transformation of starch,
and subsequently is converted into dextrin and glucose by a
true decomposition.
C18H30O15 + H2O
Starch.
C12H20O10 C6H12O6
Dextrin.
Glucose.
By the prolonged action of the acid, the dextrin itself is
converted into glucose.
The transformation of starch into dextrin and saccharine
matter (maltose) takes place easily under the influence of a
peculiar ferment which is developed in grain during germina-
tion, and to which the name diastase has been given.
may be obtained by precipitating aqueous extract of malt by
alcohol.
It
If starch be triturated with one and a half times its weight
of concentrated sulphuric acid, avoiding an elevation of tem-
perature, and the mixture be left to itself for half an hour and
alcohol then added, a substance is precipitated which is soluble
in water and assumes a rich blue tint by the action of iodine.
It is soluble starch (Béchamp).
Starch dissolves abundantly in monohydrated nitric acid,
and water precipitates from this solution a white substance,
which, after washing and drying, constitutes xyloidin. It is
mononitro-starch, and results from the substitution of a group
NO², for one atom of hydrogen in starch.
C6H1005
Starch.
+HNO3
H2O+CH°(NO2)O
Xyloidin.
Xyloidin burns with deflagration when heated to 180°.
INULIN-GLYCOGEN-GUMS.
583
INULIN.
C6H1005
This body also is largely diffused throughout the vegetable
kingdom. It exists in the roots of the elecampane (Inula
helenium), chicory, and Spanish chamomile, in the bulbs of
colchicum, the tubers of the dahlia, in the Jerusalem arti-
choke, etc. It may be extracted from the tubers of the dahlia
by reducing them to a pulp and washing the latter in a sieve
under a stream of water. The milky liquid which passes
through deposits the inulin, which consists of granules analo-
gous to those of starch. It swells in cold water, in which it
is very slightly soluble. It is very soluble in boiling water,
which again deposits it in a pulverulent form on cooling. The
aqueous solution turns the plane of polarization to the left.
It is not colored blue by iodine, which communicates to it a
fugitive, yellow-brown tint.
By long boiling with water, or by the action of dilute acids,
inulin is converted into levulose.
GLYCOGEN.
C6H1005
This body, isomeric with cellulose and starch, exists in the
animal economy. Claude Bernard discovered it in the liver,
and afterwards in the placenta. It exists also in many organs
during the foetal life. Nearly pure glycogen may be obtained
by adding a large quantity of crystallizable acetic acid to a cold
and concentrated decoction of liver. It is also precipitated
when alcohol is added to an aqueous decoction of liver. In a
pure state, it is a white, amorphous powder. When dried in
the air, it has the composition C6H12O6 (E. Pelouze). At 100°
it loses one molecule of water.
With water it forms an opalescent liquid. Alcohol and
ether do not dissolve it. Boiling with dilute acids converts it
into glucose. Iodine communicates to it a violet or brown-red
color.
GUMS.
By the names gums and mucilages are understood certain
substances existing everywhere in the vegetable kingdom, and
which dissolve or swell up in water, giving a mucilaginous
584
ELEMENTS OF MODERN CHEMISTRY.
consistence to the liquid. The gums proper are distinguished
from the mucilaginous substances, which are not really soluble.
Both furnish mucic and oxalic acids when treated with nitric
acid. Gum furnishes at the same time a small quantity of
tartaric acid.
Gum Arabic.-Gum arabic is identical with Senegal gum.
It flows naturally from different species of acacia. It dissolves
abundantly in cold water and is precipitated from its solution
by alcohol. Fremy considers that it is composed essentially of
the calcium and potassium salts of an acid which he designates
as gummic acid (arabin).
When dried at 100°, the latter body has the composition
indicated by the formula C12H22O1. It is very soluble in
water, and its solution rotates the plane of polarization to the
left.
When heated to 120-150°, it becomes insoluble in water
and is converted into metagummic acid. According to Fremy,
the gum of cherry- and plum-trees is a mixture of gummates,
which are soluble in cold water, and insoluble metagummates.
The metagummates are insoluble in water, but when boiled
with that liquid are transformed into soluble gummates.
Subacetate of lead forms an abundant white precipitate in
solutions of gum arabic.
When gum arabic is boiled with dilute sulphuric acid, it is
converted into a mixture of two saccharine substances; one is
uncrystallizable, the other crystallizes in large, colorless rhombic
prisms, having a sweet taste, and fusible at 160°. It is called
arabinose. It reduces the cupro-potassic solution and is not
fermentable. It is isomeric with glucose.
Gum Tragacanth.-This gum flows from the Astragalus of
the Levant and of Persia. Bassora gum is derived from a spe-
cies of cactus. Both contain a mucilaginous matter insoluble in
water, but which swells up in that liquid, forming a transparent
jelly. This matter is bassorin. With nitric acid, it yields much
mucic acid. When boiled with dilute sulphuric acid, it is readily
converted into crystallizable glucose.
CELLULOSE.
C6H10O5
This name is given to the matter which forms the walls of
young vegetable cells, and which is deposited, mixed with other
CELLULOSE.
585
The
matters, in the older cells, particularly in ligneous fibre.
pith of the elder and of Eschynomene paludosa, cotton, old
linen, and paper are almost pure cellulose.
In ligneous fibres, in wood, the cellulose is permeated by
various foreign substances, among which Payen has distin-
guished the incrusting matter which thickens the tissues and
gives them rigidity. Among the others are nitrogenous mat-
ters, resins, various coloring matters, etc. With these organic
substances in the ligneous fibres, are united the mineral ele-
ments which are found more or less modified in the ashes.
Old linen and cotton serve for the preparation of pure
cellulose. Such materials are boiled with a weak solution of
potassium hydrate, washed, and successively exhausted with a
solution of chlorine, acetic acid, alcohol, ether, and water, and
dried at 100°. The insoluble product which remains after this
treatment is considered as pure cellulose.
Properties. Cellulose is a diaphanous, white solid, of a
density of 1.25 to 1.45. It is insoluble in water, alcohol,
ether, and the dilute acids and alkalies. It dissolves in the
cupro-ammoniacal liquid which is obtained by dissolving cupric
hydrate or carbonate in a small quantity of concentrated am-
monia, or better, by dissolving metallic copper in ammonia in
contact with the air (Schweizer).
When submitted to dry distillation, cellulose leaves a residue
of carbon and yields numerous gaseous and liquid products.
The gas obtained by the distillation of wood is used for illu-
minating purposes in some localities. The liquid product
ordinarily separates into two layers, one of which is aqueous
and contains acetic acid, wood-spirit, acetone, etc.; the other is
insoluble in water and constitutes wood-tar.
When cellulose, charpie for example, is sprinkled with con-
centrated sulphuric acid and the mass is rapidly triturated, a
viscous mass, having but little color, is obtained; it contains,
independently of a compound of sulphuric acid and cellulose
(sulpho-ligneous acid), substances which result from the dis-
integration of the cellulose. Accordingly, as the action of the
acid is more or less prolonged, a substance is obtained which is
insoluble in water and colored blue by iodine and consequently
analogous to starch, or a soluble matter analogous to dextrin
(Béchamp). When water is added to this viscous mass and
the whole is submitted to a prolonged ebullition, fermentable
glucose is formed (Braconnot).
Z*
586
ELEMENTS OF MODERN CHEMISTRY.
C6H1005+
Cellulose.
H2O
C6H12O6
Glucose.
When paper is dipped into a cold mixture of sulphuric acid
with half its volume of water, and is then carefully washed and
dried, a semi-transparent matter is obtained which has a certain
rigidity, and is similar to parchment in aspect (Figuier and
Poumarède, Hofmann). It is called vegetable parchment.
A cold solution of chloride of zinc converts cellulose into an
amyloid matter which is colored blue by iodine; if heat be
applied, the whole is dissolved and glucose is formed.
When charpie is heated with a concentrated solution of cal-
cium hypochlorite (chloride of lime), a very violent reaction
takes place, and torrents of carbon dioxide are evolved.
Gun-Cotton.When carded cotton is immersed for half a
minute in monohydrated nitric acid, and then rapidly washed
in a large quantity of water and allowed to dry in the air, a
substance is obtained which possesses all the exterior appear-
ances of cotton, but is very inflammable and burns suddenly
without residue. It is gun-cotton, or pyroxylin, which was
discovered by Schönbein in 1847.
In its preparation, the monohydrated nitric acid may be
advantageously replaced by a mixture of one volume of fuming
nitric acid and three volumes of sulphuric acid. Pyroxylin.
seems to be a mixture of dinitrocellulose and trinitrocellulose.
C6H1005
Cellulose.
CH(NO2)205
Dinitrocellulose.
C6H7(NO2)305
Trinitrocellulose.
Gun-cotton looks like cotton, but is more harsh to the touch
and sometimes has a light yellowish tint. It burns with a
sudden flash, leaving no residue, and produces a great volume.
of gaseous products consisting of carbon monoxide, carbon
dioxide, nitrogen dioxide, etc., and vapor of water. Gun-cotton
is insoluble in water, alcohol, ether, chloroform, and the cupro-
ammoniacal solution. It is more or less soluble in a mixture
of alcohol and ether, and the solution is employed in surgery
and photography under the name collodion. When pyroxylin is
heated with a concentrated solution of ferrous chloride, nitrogen
dioxide is disengaged, and cellulose is regenerated (Béchamp).
GLUCOSIDES.
The glucosides are complex compounds, which break up
under various conditions, fixing the elements of water and
GLUCOSIDES.
587
yielding glucose and other bodies, just as the compound ethers,
in fixing the elements of water, are decomposed into alcohols
and acids.
This definition seems to relate the glucosides to the com-
pound ethers, a relation with seems legitimate, since it has
been shown by the experiments of Berthelot that glucose has
the function of a polyatomic alcohol.
Various immediate principles of vegetable origin can be
classed as glucosides. We may mention particularly the fol-
lowing:
GLUCOSIDES.
Amygdalin.
Salicin
Populin
Phloridzin
Arbutin
•
Convolvulin .
Jalappin .
Esculin
Fraxin
Daphnin.
Quinovin.
Tannin
•
FORMULAS.
C20 H27 NO11
C13H1807
C20 H2208
C21H24010
C12 II1607
C31 H50016
C34 H56016
C21H24013
C27 H30017
C31 H34019
C30 II 4808
C271122017
bitter almonds.
ORIGIN.
willow and poplar bark.
bark and leaves of the aspen.
bark and roots of fruit-trees.
leaves of the Arctostaphylos uva ursi.
jalap-root.
bark of India chestnut.
bark of the ash.
Daphne alpina, Daphne mezereum.
bark of China nova.
oak-bark, nut-galls, etc.
Among all of these bodies, we will only consider amygdalin,
salicin, populin, phloridzin, and tannin, or tannic acid.
Amygdalin, CH"NO".-This body is extracted from the
cake of bitter almonds, and it deposits from its alcoholic solu-
tion in crystals containing two molecules of water. Its aqueous
solution allows it to crystallize in quite large crystals contain-
ing three molecules of water.
Amygdalin is very soluble in water and in boiling alcohol.
Its aqueous solution rotates the plane of polarization to the
left.
By the action of dilute acids amygdalin is decomposed into
hydrocyanic acid, benzoyl hydride, or benzoic aldehyde (oil of
bitter almonds), and glucose.
C20 H7NO¹¹ + 2H²0 = CHO + CHN + 2CH2O
Amygdalin.
Benzoic
aldehyde.
Hydrocyanic
acid.
+
Glucose.
The same decomposition takes place by the action of water
and a peculiar ferment which is contained in both bitter and
sweet almonds, and which is called emulsin, or synaptase. It
is a nitrogenized matter, soluble in water, and only acts on
amygdalin in presence of water. It is well known, indeed, that
588
ELEMENTS OF MODERN CHEMISTRY.
bitter almonds only develop the odor of prussic acid when
moistened with water.
18
Salicin, C¹³H¹807.—Salicin exists already formed in the bark
of the willow and poplar. Wöhler discovered its existence in
castoreum. It may be prepared by exhausting willow-bark
with boiling water, concentrating the liquid and digesting it
with litharge. The solution is then filtered and evaporated to
a syrupy consistence; the salicin deposits in a few days.
It occurs in small scales, or brilliant needles, soluble in water
and alcohol and insoluble in ether. Its aqueous solution turns
the plane of polarization to the left.
Salicin dissolves in sulphuric acid, forming a red liquid.
By the action of a solution of emulsin (the nitrogenous mat-
ter of almonds), it breaks up into a neutral body called salige-
nin, and glucose.
C¹³H¹807 + H2O
Salicin.
C'H³O² + CH¹²O
Saligenin.
Glucose.
Dilute sulphuric and hydrochloric acids decompose it by
the aid of heat into saliretin and glucose. These bodies will
be described farther on.
When salicin is fused with potassium hydrate, hydrogen is
disengaged, and salicylic and oxalic acids are formed.
By the action of a mixture of potassium dichromate and
sulphuric acid, salicin yields carbon dioxide, formic acid, and
an oxidized oil, which is the hydride of salicyl or salicylic alde-
hyde, C'HO² (Piria).
Populin, C20 H2208 + 2H2O.—Braconnot discovered this sub-
stance in the bark and leaves of the aspen (Populus tremula).
To extract it, those substances are exhausted with boiling water,
the decoction is precipitated by subacetate of lead, filtered, and
the filtrate evaporated to a syrupy consistence. On cooling,
the populin is deposited as a crystalline precipitate. When
properly purified, it occurs in very fine, silky, colorless needles.
Its taste is sweet; it is but slightly soluble in water, more
soluble in alcohol. By the action of dilute acids, it is decom-
posed into benzoic acid, saliretin, and glucose; the latter two
products result from the decomposition of salicin, so that popu-
lin appears to be a combination of benzoic acid and salicin.
C20H2208+ H2O
Populin.
C'HO² + C13H1807
Benzoic acid.
Salicin.
Phloridzin, C2H24O10+ 2H2O.-This substance exists in
GLUCOSIDES.
589
the bark of apple, pear, plum, and cherry trees, and principally
in the roots of fruit-trees. It may be extracted by boiling the
roots with water, decanting the boiling solution, concentrating
it, and allowing it to stand in a cool place. The phloridzin
deposits on cooling, and may be purified by recrystallization
after decolorizing it with animal charcoal.
When pure, it forms colorless, silky needles, having a bitter
taste, and an after-taste which is sweet. It is scarcely soluble
in cold water, but dissolves abundantly in boiling water and
in alcohol. The alcoholic solution turns the plane of polariza-
tion to the left.
Dilute sulphuric and hydrochloric acids decompose it into
phloretin and glucose.
C21H24O10+ H2O
Phloridzin.
C¹³H¹405 + C6H12O6
Phloretin.
Glucose.
Phloretin is a white substance which crystallizes in little
scales, slightly soluble in water and very soluble in alcohol.
When phloretin is heated with potassium hydrate, it breaks up
into phloretic acid and phloroglucin.
C¹³¹О5 + H³0 =
Phloretin.
C9H10O3 + C‘HĜO³
Phloroglucin.
Phloretic acid.
་
Phloroglucin forms large crystals having a sweet taste.
Tannin, or Tannic Acid, CHO".-The names tannins
and tannic acids are applied to certain slightly acid compounds
which are largely diffused in the vegetable kingdom, and which
have two important properties: they precipitate solutions of
gelatin and albuminous matters, and produce a bluish or
greenish-black color with the ferric salts. The most important
of these compounds, the tannin of oak bark, or quercitannic
acid, is a glucoside. By the action of dilute acids it is decom-
posed into gallic acid and glucose (Strecker).
Tannin exists in oak bark, in sumac, and in large quantities
in nut-galls, which are excrescences developed by the sting of
an insect on the leaves and branches of the Quercus infectoria.
It is prepared by introducing coarsely-powdered nut-galls into
a percolator, and exhausting them with ordinary commercial
ether. The ethereal solution which passes through is collected
in a flask, and in the course of a day separates into two or
sometimes three layers. The lower layer is a very concen-
trated, aqueous solution of tannin. It is separated and dried
50
590
ELEMENTS OF MODERN CHEMISTRY.
The tannin remains as a light, bulky mass,
in a hot-air oven.
having a yellowish color.
Tannin is a colorless, amorphous solid, having a very astrin-
gent taste.
It is very soluble in water, less soluble in alcohol,
insoluble in pure ether.
It melts when heated, and between 210 and 215° it dis-
engages carbon dioxide and yields pyrogallol, CHO³, which
volatilizes. A black residue remains (metagallic acid).
On contact with the air, the aqueous solution of tannic acid
absorbs oxygen, disengages carbon dioxide, and deposits gallic
acid. This transformation takes place more rapidly when oak
tannin is boiled with dilute sulphuric or hydrochloric acid.
C27H22O¹7 + 4H²O 3C'H605 + C6H12O6
Tannin.
Gallic acid.
Glucose.
The researches of H. Schiff seem to show that tannin, prop-
erly speaking, is not a glucoside but is digallic acid, C¹¹¹ºÒ³,
that is, an acid derived from two molecules of gallic acid by the
subtraction of one molecule of water. By fixing the elements
of water, a molecule of tannin would form two molecules of
gallic acid.
C¹¹H¹009 +- H2O
Digallic acid.
2C7H605
Gallic acid.
A solution of tannic acid produces with ferric salts a bluish-
black precipitate, which constitutes ink. Tannin does not color
ferrous salts, but the mixture soon blackens on exposure to the
air by absorbing oxygen.
Tannin is employed in medicine as an astringent. Nut-galls,
which are very rich in tannin, are used for the manufacture of
ink. A good ink may be prepared by the following receipt:
One kilogramme of powdered nut-galls is exhausted with 14 litres
of water; the solution is filtered, and a solution of 500 grammes
of gum arabic is first added, then a solution of 500 grammes of
ferrous sulphate (green vitriol). The mixture is well stirred up,
and then exposed to the air until it has acquired a fine black color.
AROMATIC COMPOUNDS.
The compounds which we have studied thus far are rich in
atoms of hydrogen. Most of them are saturated or derived
from saturated compounds. The hydrocarbons of the series
CnH2n+2, the alcohols CnH2n+2O, the fatty acids CnH2O2, are
AROMATIC COMPOUNDS.
591
of these classes of compounds the most rich in hydrogen that
are known; they belong to what is called the futty series. But
there are other compounds which possess, like the preceding,
the characters of hydrocarbons, alcohols, and acids, in which
the relation between the atoms of carbon and of hydrogen is not
the same.
The atoms of the latter element decrease in num-
ber in proportion to those of the former. These relations may
be understood by a glance at the following formulæ :
C10H22 decane.
C10H20 decylene.
C10H18 menthene.
C10H16 turpentine.
C10H14 cymene.
C10H8 naphthalene.
C10H220 decyl hydrate.
C10H1200 mint camphor.
C10H180 Borneo camphor.
C10H160 ordinary camphor.
C10H140 thymol.
C10H120 cuminic aldehyde.
A large number of these unsaturated compounds belong
or are related to those aromatic substances which are called
essences or essential oils. Hence the name aromatic com-
pounds, which has been given to all of these bodies containing
but little hydrogen.
The most interesting of the hydrocarbons of the aromatic
series is benzol, which is now obtained in large quantities from
coal-tar. It is as important by reason of the applications which
it has received in the arts as on account of the theoretical con-
siderations which attach to it. Kekulé has made it the centre
of the aromatic series which would include, in a limited sense,
only the derivatives of benzol. In a word, the latter body is
the nucleus of all the aromatic compounds.
Kekulé's theory considers that the 6 atoms of carbon of
benzol form a closed chain, each being bound to its neighbors,
on one side by one, and on the other by two bonds of saturation.
One atom of hydrogen is attached to each of these carbon atoms.
H
H-C C-H
H-C C-H
C'
H
Benzol.*
* In this formula, the connecting lines indicate the saturation of the
atomicities; the double lines indicate the exchange of two atomicities
between two neighboring atoms of carbon.
592
ELEMENTS OF MODERN CHEMISTRY.
Very numerous and very different aromatic compounds are
derived by the substitution of different elements or groups for
the hydrogen atoms in the molecule of benzol, that molecule
forming, so to speak, the nucleus of all the aromatic com-
pounds.
1. If one atom of hydrogen be replaced by chlorine or bro-
mine, monochlorobenzol or monobromobenzol will result, these
compounds being also called chloride and bromide of phenyl.
C6H6
Benzol.
C6H5Cl
Monochlorobenzol.
C6H³Br
Mohobromobenzol.
2. If one atom of hydrogen be replaced by the group hy-
droxyl (OH), phenol, or phenyl hydrate, is formed. The sub-
stitution of two hydroxyl groups for two atoms of hydrogen
produces the oxyphenols; that of three groups OH for three
atoms of hydrogen produces phloroglucin (page 618).
C6H6
C6H5.OH
Benzol.
Phenol.
C6H4
OH
он
Oxyphenol and
its isomerides.
он
C6H3 он
он
Phloroglucin and
its isomerides.
3. The substitution of one or more groups (NO²)' for one
or more atoms of hydrogen gives rise to the nitro-derivatives.
C6H6
Benzol.
C6H5-N02
Nitrobenzol.
NO2
C6H4
NO2
Dinitrobenzol.
4. The substitution of the group (NH2) for one atom of
hydrogen produces phenylamine, or aniline; that of two groups
NH' for two atoms of hydrogen yields phenylene-diamine.
C6H6
Benzol.
C6H5_NH2
Phenylamine (aniline).
C6H4
NII2
NH2
Phenylene-diamine
and its isomerides.
5. If one or more atoms of hydrogen in benzol be replaced
by as many methyl groups, CH³, the superior homologues of
benzol are obtained.
benzol.
C6H6
C6H6
C7H8
C6115-CH3
toluol (methylbenzol).
CH3
C8H10
C6H4
CH3
xylol and isomerides (dimethylbenzols).
CH3
C9H12
C6H3
CH³ mesitylene and isomerides (trimethylbenzols).
CH3
C12 II18- C(CH3)6 hexamethylbenzol.
One ethyl group can replace one atom of hydrogen in ben-
AROMATIC COMPOUNDS.
593
zol, and ethylbenzol, which is isomeric with dimethylbenzol,
would result.
C6H5-C2H5
Ethylbenzol.
CH3
C6H4
CH³
Dimethylbenzol.
There are many instances of such isomerism, and they re-
ceive the same interpretation.
One atom of hydrogen in benzol may be replaced by a propyl
group, CH, and propyl benzol, which is isomeric with trimethyl-
benzol, is the result.
One atom of hydrogen may be replaced by an ethyl group
and another by a methyl group, and the new compound would
be ethyl-methylbenzol, isomeric with propylbenzol and with tri-
methylbenzol.
C6H5-C3H7
Propylbenzol (cumene).
C6H4.
C2H5
CH3
Ethyl-methylbenzol.
CH3
C6H3
-CH3
CH3
Trimethylbenzol.
These alcoholic radicals which are thus substituted for the
hydrogen of benzol, constitute, according to the expression of
Kekulé, lateral chains, which are grafted, so to speak, on the
benzol nucleus or principal chain.
CO2H,
6. The aromatic acids, properly speaking, result from the
substitution of one or more carboxyl groups, CO.OH
for one or more hydrogen atoms in the benzol nucleus.
C6H6
C6H5-CO2H
C6H4.
Benzol. Benzoic acid.
CO2H
CO2H
Phthalic acid
and isomerides.
C6H3(CO2H)3
Trimesic acid
and isomerides.
C6(CO2H)6
Mellic acid,
7. In the homologues of benzol, the substitution of Cl, Br,
OH, NH², CO³H, etc., for hydrogen, may take place either in
the benzol nucleus or in the lateral chain: isomeric compounds
are thus formed.
a. By substitution of one atom of chlorine for an atom of
hydrogen in toluol, two isomeric compounds, C'H'Cl, may be
obtained. In one, the chlorine will be attached to the lateral
chain; in the other, it will be attached to the benzol nucleus,
as is the group CH³ itself.
C6H5-CH³
Toluol.
C6H5-CH2CI
Benzyl chloride.
C&H + CH3
Chlorotoluol.
b. The phenols result from the substitution of OH for an
atom of hydrogen in the nucleus. If this substitution take
place in a lateral chain, an aromatic alcohol, isomeric with the
corresponding phenol, is obtained.
50*
594
ELEMENTS OF MODERN CHEMISTRY.
C6H5-CH3
Toluol.
C6H5-CII2(OH)
Benzylic alcohol.
OH
C6H4.
CH3
Cresol.
c. The substitution of a carboxyl group, CO'H, for an atom
of hydrogen in the benzol nucleus of toluol, CH5-CH³, pro-
duces the aromatic acids, toluic acid, and its isomerides; if,
however, the carboxyl replace a hydrogen atom in the lateral
chain, CH³, alpha-toluic acid, isomeric with the preceding acids,
results.
C6H5-CH3
Toluol.
C6H4
CH3
CO2H
Toluic acids.
C6I15-CH2-CO2H
a-toluic acid.
d. When two groups OH are substituted for two atoms of
hydrogen in the principal chain, oxyphenols are formed.
CH³
C6H3--OH
OH
Orcin.
e. The substitution of the group NH2 for one atom of hydro-
gen in the principal chain, on the one hand, and in the lateral
chain, on the other, produces isomeric alkaloids.
C6H5-CH(NH2)
Benzylamine.
C6II4
NH2
CH³
Toluidine.
8. This is not all; the lateral chains may be grafted at dif-
ferent points of the benzol nucleus by substitution for the dif-
ferent hydrogen atoms. Their positions and their relative dis-
tances from each other are the causes of numerous isomerisms.
It is important to understand the principle of this isomer-
ism. Let us consider the most simple case, that in which
two atoms of hydrogen are replaced by two other monatomic
atoms or monatomic groups. Such compounds are the di-
substituted derivatives of benzol, and experiment has shown.
that there are three di-substituted derivatives of each kind.
Thus there are three hydrocarbons containing two groups
CH³, each substituted for one atom of hydrogen in benzol;
three phenols, each containing two groups OH; three acids,
each containing one group CO H, and one group OH, substi-
tuted each for one atom of hydrogen, and three acids, each
containing two carboxyl groups substituted for two atoms of
hydrogen. Indeed, this substitution may take place in three
different ways.
The six carbon atoms forming a closed chain
and a hydrogen atom being attached to each carbon, the re-
AROMATIC COMPOUNDS.
595
META-DERIVATIVES.
placement of two atoms of hydrogen may affect two adjoin-
ing atoms of carbon, or two atoms of carbon separated by a
third atom of carbon which still retains its H, or lastly, two
carbon atoms which are separated by two other carbon atoms,
each of which still retains its H. The relative positions of the
groups being different in each case, it results that the molecules
present different structures and are consequently isomeric. The
following examples will explain this kind of isomerism.
Ortho-derivatives are those in which the hydrogen of two
adjacent carbon atoms is replaced; meta-derivatives are those
in which the two carbon atoms affected are separated by a third;
para-derivatives are those in which the two carbon atoms are
separated by two others.
CH3
HC
HC
11
=
C
Ć
C-CH3
I
CH
он
он
CO2H
را
HC
C-OH HC C-CO2H
HC
Hó
не сн
IT
C-CO²H
HỒ CH
не сн
CH
C
H
C
Orthoxylol.
H
Orthodiphenol
(pyrocatechin).
H
H
Orthoxybenzoic
acid
(salicylic).
Orthophthalic
acid
(phthalic).
IIC
IIC
"
11
CH3
Ć
CH
||
C-CH3
он
C
"
HC
CH
OH
HC
CH
CO2H
"
HC
CH
с-сон
HC Ć-OH | HC -CO2H | HCC-CO2H
нс сон
C
H
H
Metaxylol.
Metadiphenol
(resorcin).
H
Metoxybenzoic
acid
(oxybenzoic).
H
Metaphthalic acid
(isophthalic).
CH³
"1
IIC CH
не он
HĆ
CH
сиз
"1
он
Ć
HC CH
HC CH
C
он
Paraxylol.
Paradiphenol
(hydroquinone).
را
он
HC CH
HC
но
HỒ CH
но
C
CO2H
CO2H
Paroxybenzoic
acid.
11
C
CH
JI
CH
созн
Paraphthalic acid
(teraphthalic).
*
596
ELEMENTS OF MODERN CHEMISTRY.
These indications will suffice to illustrate the class of isomer-
ides under consideration. With the tri-substituted derivatives
of benzol, theory foresees and experiment has demonstrated the
existence of still more numerous isomerides, but we cannot
dwell on them here.
Two very important hydrocarbons are now considered as
directly related to benzol. They are naphthalene, CH, and
anthracene, C14H10.
Naphthalene is formed by the union of two benzol nuclei,
two atoms of carbon being common to each nucleus (Erlen-
meyer).
Anthracene results from the union of two benzol nuclei by
the intermediation of two carbon atoms, which are themselves
combined together, each by one atomicity, and each of which
is combined with one atom of hydrogen (Graebe).
These ideas are indicated in the following graphic formula,
which express the reciprocal relations between the atoms of
carbon and hydrogen, but not their real positions in space. The
latter might be better indicated by a polyhedral form.
C
H
H H
C
C
HC
CH
Ho C
CH
HỒ CH
HỒ Ở CH
H
C H C
H
CH
HC `C-C-C
HC C-C-C он
空​營​營
​H
Benzol.
H H
Naphthalene.
C H
H
H
Anthracene.
We must with these brief indications conclude the considera-
tion of the principles of Kekulé's theory, which includes very
many compounds. These are the aromatic compounds in the
strict sense of the word. Before undertaking their study, we
will briefly describe oil of turpentine and some of the bodies
allied to it.
OIL OF TURPENTINE AND ITS ISOMERIDES.
A large number of hydrocarbons are known having the com-
position C10H16. Some are the natural products which consti-
tute the whole or part of the numerous essential oils. Others
are the products of art.
Among the first are the oils of turpentine, lemon, orange,
bergamot, orange-flower, juniper, savin, lavender, cubebs, co-
paiba, elemi, pepper, cloves, etc.
TURPENTINE.
597
These oils are liquids; some of them are mixed with oxy-
genized solid bodies which are deposited in time, and which
were formerly designated as stearoptenes.
They are obtained by distilling the vegetable products which
contain them with water, for, although the boiling-points of
these oils are between 150 and 200°, they distil readily with
aqueous vapor, and collect in the form of a layer on the sur-
face of the condensed water.
The more ordinary process consists in passing a current of
steam through the plants or aromatic vegetables. For this
purpose they are placed on a diaphragm, M (Fig. 129), which


TH
Ꭲ"
M
FIG. 129.
is fixed above the bottom of an ordinary still. The head of
the still is then adjusted, connection is made with a condenser,
and a current of steam is passed in by the tube TT'T", which
penetrates into the still. The steam carries with it the essen-
tial oil, which diffuses in it by virtue of
the high tension of the vapor of these oils at
100°. The mixed vapors rise into the head
of the still and condense in the condensing
worm. The condensed water, generally
clouded by little drops of the essential oil,
is received in a vessel of peculiar form,
which is called a Florentine receiver. It is
shaped like an ordinary flask (Fig. 130),
having at its bottom a tube which curves
upwards, in the form of a swan's neck, and
the
upper part of which is but little below
the mouth of the flask. As the condensed water and oil collect
in this ingenious apparatus, the oil separates and floats on the
water; as the distillation continues, the liquid rises not only in

FIG. 130.
598
ELEMENTS OF MODERN CHEMISTRY.
the flask, but in the lateral tube, until the water, which is
always in large excess, reaches the level of the curved neck
and flows off alone, the lighter oil accumulating in the flask.
Among the essential oils whose composition is represented
by the formula C10H16, the most important is oil of turpentine,
which is obtained by distilling the turpentine of commerce with
water. Turpentine is a mixture of resin and essential oil, and
flows from incisions cut in the trunks of trees of the genera
Pinus, Abies, Picea, Larix.
When this resinous substance is distilled with water, the oil
passes over and the resin remains; the latter is called colo-
phany, or rosin.
Turpentine.-Bordeaux turpentine, which comes from the
Pinus maritima (Pinus Pinaster), yields, by distillation with
water, an essential oil which boils at 156°, and turns the plane
of polarization to the left. Density at 0°, 0.877.
Australine, or English oil of turpentine, which comes from
the Pinus Australis, has the same boiling-point as the preced-
ing, but turns the plane of polarization to the right. Density
at 16°, 0.864 (Berthelot). American oil of turpentine, derived
from Pinus palustris, is also dextrogyrate.
Metamorphoses of Oil of Turpentine.-1. When exposed
to the air, oil of turpentine gradually absorbs oxygen, becomes
yellow and partly resinified. This slow oxidation is due to the
production of ozone, with which the oil becomes charged; it
then possesses oxidizing properties (page 61).
2. Concentrated nitric acid oxidizes oil of turpentine with
such energy that the mixture sometimes takes fire. When
boiled with dilute nitric acid, it forms teraphthalic acid,
one of the isomerides of phthalic acid (Cailliot).
ᏟᎻ
C6H⭑<
CO2H
CO2H'
3. When a mixture of alcohol, nitric acid, and oil of turpentine
is left to itself for some time, the latter substance fixes the ele-
ments of three molecules of water and is converted into a crys-
tallized solid body, C10H2002 + H2O, called terpin.
20
32
4. When oil of turpentine is mixed with its weight of
concentrated sulphuric acid, and the mixture is agitated, it is
converted into an isomeric hydrocarbon, terebene, which boils
at 156°, and a polymeric hydrocarbon, C20H2, which boils
between 310 and 313° (H. Deville). By reason of the re-
ducing action which the oil of turpentine exerts on the sul-
phuric acid, and which produces sulphurous oxide and water,
TURPENTINE.
599
two atoms of hydrogen are removed from the molecule C10H16,
and, independently of terebene, a certain quantity of cymene,
C10H14, is formed (Riban).
2
14
C¹0H16+ SO¹H² C¹¹ºH¹¹ + SO² + 2H²O
5. The hydracids combine with oil of turpentine. Three com-
pounds of turpentine and hydrochloric acid are known. A solid
hydrochloride, CH16.HCl, is deposited from cooled oil of tur-
pentine by the action of gaseous hydrochloric acid, and is called
artificial camphor. It is levogyrate, or dextrogyrate, accord-
ingly as it has been prepared from turpentine or australine.
The crystals are deposited from a very acid, colorless liquid, con-
taining a liquid combination of turpentine and hydrochloric acid.
When oil of turpentine is left for a month in contact with
very concentrated hydrochloric acid, a dihydrochloride is
formed, CH16.2HCl. It is a solid body, and is identical or
isomeric with the artificial camphor of oil of lemon, obtained
by passing hydrochloric acid gas into oil of lemon.
6. Antimony trichloride transforms oil of turpentine into a
solid polymeride, tetraturpentine.
Terebene. Terebene, which has already been mentioned,
boils at 156°, like its isomeride, oil of turpentine, from which
it differs by being optically inactive; it forms no crystalline
hydrate corresponding to terpin, and it never yields a dihy-
drochloride. Like turpentine, it forms a crystalline monohy-
drochloride when subjected to the action of hydrochloric acid
gas (Riban).
Camphenes. When dextro- or levo-artificial camphor is
heated to between 200 and 220° with sodium stearate, HCI
is removed, and the camphor is transformed into a solid, crys-
tallizable hydrocarbon, fusible at 146°, and boiling at 160°.
It is camphene, and is optically active in the same direction as
the hydrochloride, from which it is derived.
The sodium stearate here acts as a feeble alkali; when it is
replaced by sodium benzoate, inactive camphene is set at lib-
erty. The camphenes yield only monohydrochlorides by the
action of hydrochloric acid gas (Berthelot).
The hydrochlorides of turpentine, terebene, and camphene
are isomeric; the first is almost undecomposable by water at
100°, the second loses all of its hydrochloric acid by the action
of boiling water, and it is the same with the third, which, how-
ever, regenerates solid camphene (Riban).
600
ELEMENTS OF MODERN CHEMISTRY.
Isoturpentine.-When oil of turpentine is heated to 300°,
it is transformed into a new isomeride, which is active and
levogyrate it is isoturpentine, and boils towards 176°. Den-
sity at 0°, 0.859. At the same time as isoturpentine, meta-
turpentine is formed, C20H32, boiling at 360°.
Terpilene. This is another isomeride of oil of turpentine,
and boils at the same temperature. It is obtained by removing
all of the hydrochloric acid from the dihydrochloride, C¹ºH16.
2HCl, by the action of either sodium (Berthelot) or aniline
(Lauth and Oppenheim).
It is characterized by the fact that it yields a dihydrochlo-
ride with great ease by the action of gaseous hydrochloric acid,
and does not form a monohydrochloride.
Citrene, C¹ºH16.-This hydrocarbon is contained in oil of
lemon, together with an oxygenized body. It is a colorless.
liquid, having an agreeable odor. It boils at 173-174°. Den-
sity at 15°, 0.85.
Citrene unites readily with hydrochloric acid, producing a
crystalline dihydrochloride of citrene, C10H16.2HCl, fusible at
14°.
ORDINARY CAMPHOR, OR LAUREL CAMPHOR.
(10H160)
Camphor exists in all of the organs of the Laurus camphora,
a tree of China, Japan, and the islands of the Bay of Sundy.
When the wood is chipped and distilled with water, the cam-
phor volatilizes and condenses in rice-straw, with which the
heads of the stills in which the operation is conducted are filled.
The product thus obtained in the form of small crystals is re-
fined by sublimation in glass vessels heated on a sand-bath.
A camphor identical with laurel camphor is deposited from
the oil of Matricaria parthenium when the latter is cooled.
It is matricaria camphor.
Camphor forms a semi-transparent, crystalline mass. Its
odor is strong and aromatic; its taste, bitter and burning. It
melts at 175°, and boils and distils without alteration at 204°.
Its density at 0° is 1.0. At ordinary temperatures, the ten-
sion of its vapor is so great that it sublimes spontaneously in
the vessels in which it is kept.
Camphor is almost insoluble in water; when thrown in
CAMPHOR.
601
small fragments on the surface of that liquid, it executes gyra-
tory movements. It dissolves in alcohol and ether, and the al-
coholic solution rotates the plane of polarization to the right.
Camphor is inflammable, and burns with a smoky flame.
The following are its principal reactions:
1. When heated with phosphoric anhydride, or with chloride
of zinc, it loses the elements of water and is converted into a
hydrocarbon called cymene.
14
C¹ºH¹60 = H2O + C¹ºH¹¹
Camphor.
Cymene.
2. Camphor appears to be an aldehyde. Although it does
not fix hydrogen directly, it can nevertheless be converted into
a compound, CH18O, which is borneol, or Borneo camphor.
This is accomplished by the action of sodium, which replaces
the hydrogen of a portion of the camphor, forming a sodium-
camphor, while the displaced hydrogen is fixed upon another
portion of camphor (Baubigny).
According to this reaction, corroborated by the inverse re-
action, which will be indicated farther on, the same relations
seem to exist between borneol and camphor as between alco-
hol and aldehyde.
C²H¹O
Aldehyde.
CHO
Camphor.
C2H6O
Alcohol.
C10H180
Borneol.
3. When camphor is heated for a long time with an alcoholic
solution of potassium hydrate, it is decomposed into an acid
and an alcohol, which is borneol (Berthelot).
2C10H160 + KOH
Camphor.
C10H15KO² + C10H180
Potassium camphate.
Borneol.
4. When vapor of camphor is passed over soda-lime, heated
to about 300°, the sodium salt of campholic acid is obtained
(Delalande).
110
CHO + NaOH
Camphor.
C¹¹0H17NaO2
Sodium campholate.
5. When camphor is subjected to the action of aqueous
hypochlorous acid, it is converted into monochloro-camphor,
CiH15CIO, which constitutes a colorless, crystalline mass,
slightly soluble in water, freely soluble in alcohol and ether,
and fusible at 95°.
2A
51
602
ELEMENTS OF MODERN CHEMISTIY.
6. By the action of bromine on camphor at 100 or 120°,
monobromo - camphor, C¹ºHBrO, and dibromo - camphor,
C10H14Br²O, are formed. These bodies crystallize in colorless
prisms. The first fuses at 76°, the second, at 114°.
A bromide of camphor, CHOBr2, is also known; it is
formed by the action of bromine on a solution of camphor in
chloroform. It is a crystalline body which decomposes spon-
taneously, especially by the action of light, losing hydrobromic
acid and being converted into monobromo-camphor.
7. Camphor absorbs hydrochloric acid gas, forming an oil
which is instantly decomposed by water, regenerating camphor.
Cold nitric acid dissolves it, forming an oily liquid which is de-
composed by water, camphor being precipitated.
8. When camphor is boiled with nitric acid, it is oxidized
and converted into camphoric acid.
CH160 + 03
Camphor.
C10H160*
Camphoric acid.
BORNEOL, OR BORNEO CAMPHOR.
C10H180
This camphor is extracted from the Dryobalanops aromatica,
a tree which grows in the Sundy Islands. Berthelot has ob-
tained it by the action of an alcoholic solution of potassa on
ordinary camphor. It occurs in small, colorless, transparent,
and friable crystals. Its odor recalls at the same time that of
camphor and that of pepper. Its taste is burning. It melts
at 198°, and boils at 212°. It turns the plane of polarization
to the right. It is insoluble in water, but dissolves readily in
alcohol and in ether. When treated with cold, fuming nitric acid,
it loses H², and is converted into ordinary camphor, C¹ºH¹6O.
BENZOL.
C6H6
This important body was discovered in 1825 by Faraday.
Mitscherlich obtained it by heating benzoic acid with an excess
of lime.
C7H6O2
CO² + C6H6
Benzoic acid,
Benzol.
It is now obtained in large quantities from coal-tar by dis-
tilling the latter body. The more volatile products contain the
BENZOL.
603
benzol, which is purified by fractional distillation. That which
passes below 85° is principally benzol, and the latter crystal-
lizes out when the liquid which passes between 80 and 85° is
cooled to —5°. . The crystals are collected and separated by
expression from the product remaining liquid. They constitute
pure benzol.*
Berthelot has recently made the direct synthesis
of benzol by exposing acetylene to a temperature near redness.
3C2H2
C6H6
Acetylene.
Benzol.
Benzol is a colorless, strongly refracting liquid. At 0°, it
solidifies to crystals which melt at 5.5°. It boils at 80.5°.
It is insoluble in water, but dissolves in alcohol and ether. It
is inflammable, and burns with a bright, smoky flame.
When long agitated with fuming, or even ordinary sulphuric
acid, it dissolves, forming phenylsulphurous acid.
CH® + H²SO¹
H2O + C'H³.SO³H
Phenylsulphurous acid.
When heated to 275 or 280° for twenty-four hours with 80
to 100 parts of concentrated hydriodic acid, benzol is converted
into hexane, CH¹, iodine being set free.
Action of Chlorine and Bromine on Benzol.-In sun-
light, benzol can absorb directly six atoms of chlorine, forming
benzol hexachloride, CH C1, crystallizable in brilliant plates.
Another product of the action of chlorine on benzol is mono-
chlorobenzol, CH5Cl, a liquid, boiling between 135 and 137°.
An excess of bromine in sunlight converts benzol into a solid
bromide, CH Brº.
Monobromobenzol, CH³Br, may be made by mixing benzol
and bromine in the proportion of one molecule of the first to
two atoms of the second, and leaving the mixture to itself for
a week at the ordinary temperature. It is then washed, first
with water then with potassa, and distilled. Monobromobenzol
boils at 152-154°. When heated with sodium, it yields to the
C6H5
10
latter its bromine, and a hydrocarbon C¹¹0=C6ITS called
diphenyl, is obtained.
Dibromobenzol, CH Br², is readily formed by the action of
an excess of bromine on benzol. It crystallizes in beautiful
prisms, fusible at 89°. It boils at 219°.
Benzol must not be confounded with the benzine derived from petro-
leum, which is a saturated hydrocarbon.
604
ELEMENTS OF MODERN CHEMISTRY.
Nitrobenzol, C6H5(NO2).-If benzol be poured in small
portions into monohydrated nitric acid, and water be added to
the mixture, an oily, yellow liquid separates, constituting nitro-
benzol.
H²O
C6H6 + HNO3 = H2O + CH5(NO2)
It is benzol in which one hydrogen atom is replaced by the
group (NO²)'.
Nitrobenzol is a yellowish liquid, having a strong odor of
bitter almonds. It boils at 205°, and solidifies at 3°. It is
employed in perfumery under the name essence of Mirbane.
By the action of reducing agents, such as hydrogen sulphide,
ammonium sulphide, tin and hydrochloric acid, or iron-filings
and acetic acid, nitrobenzol is converted into aniline or phenyl-
amine.
C6H5(NO²) +
+ 3H2
Nitrobenzol.
2HO + CH(NH3)
Aniline.
When long heated with very concentrated nitric acid, nitro-
benzol is transformed into metadinitrobenzol, CH*(NO2), which
forms long, right rhombic prisms, fusible at 118°.
Azoxybenzol, Azobenzol, Hydrazobenzol.-There are other
products of the reduction of nitrobenzol, independently of
aniline. When nitrobenzol is acted upon by alcoholic potas-
sium hydrate, or by sodium amalgam in presence of water, the
reduction is less complete, and it is converted successively into
azoxybenzol and azobenzol (Zinin).
C6H5-N
2C6H5-N02 + 3H2
Nitrobenzol.
3H20
+
C6H5-N
Azoxybenzol.
C6H5-N
2C6H5-NO² + 4H²
=
4H20
+
C6H5-N
Nitrobenzol.
Azobenzol.
Azoxybenzol forms long, yellow prisms, fusible at 36°, very
soluble in alcohol and ether.
Azobenzol forms large, red crystals, fusible at 66.5°. It
boils without decomposition at 293°. It is insoluble in water,
but dissolves in alcohol and ether.
In the presence of reducing agents, such as hydrogen sul-
phide, ammonium sulphide, or sodium amalgam and water,
both of the preceding bodies fix hydrogen and are converted
into hydrazobenzol.
CYANOBENZOL-PHENOL.
605
C6H5-N
C6H5-N
Azobenzol.
C6H5_NH
+ H2
C6H5_NII
Hydrazobenzol.
When
The latter body crystallizes in tables, fusible at 131°, almost
insoluble in water but soluble in alcohol and ether.
submitted to dry distillation, it breaks up into azobenzol and
aniline.
2C12H¹2N2
Hydrazobenzol.
C¹²H¹0N2 + 2C6H5NH2
Azobenzol.
Aniline.
CYANOBENZOL.
(PHENYL CYANIDE, BENZONITRILE.)
C6H5.CN
This body is formed in various reactions, particularly in the
destructive distillation of hippuric acid, and by the dehydration
of benzamide by phosphoric anhydride.
CH_CO.NH
Benzamide.
H2O
C6H5-CN
Benzonitrile.
It is a colorless oil, which boils at 191°. When heated with
the alkalies, it yields benzoic acid and ammonia.
C6H5-CN+ 2H2O
Benzonitrile.
CH-COH + NH3
Benzoic acid.
PHENOL, OR PHENYL HYDRATE.
C6H5.OH
This body bears the same relation to benzol that wood-spirit
does to marsh gas.
CH¹
Methane.
C6H6
Benzol.
CH3.OH
Methyl hydrate.
C6H5.OH
Phenol.
It was discovered in coal-tar by Runge, who named it car-
bolic acid. Laurent demonstrated that it plays the part of an
alcohol. Indeed, it presents points of resemblance with the
monatomic alcohols, but it differs from them by its acid char-
acter, on account of which it is sometimes called phenic acid.
Preparation. Large quantities of phenol are obtained from
coal-tar, from which it is separated by distillation. That part
which passes between 150 and 200° is collected apart and
51*
606
ELEMENTS OF MODERN CHEMISTRY.
mixed with a saturated solution of potassium or sodium hy-
drate to which solid potassa or soda is added. A crystalline
phenate of potassium or sodium is formed; it is dissolved in
boiling water, the insoluble oil which floats is separated, and
the alkaline solution is neutralized with hydrochloric acid.
The phenol separates; it is washed with a small quantity of
water, dehydrated with calcium chloride, and rectified. The
distilled product is cooled to -10°, and the crystals which are
deposited are allowed to drain out of contact with the air.
Phenol may be made artificially from benzol by a process
which is applicable to the preparation of all the phenols. It
consists in treating benzol with fuming or even ordinary
sulphuric acid. Phenylsulphurous acid is formed; this is
diluted with water to separate the excess of hydrocarbon, and
the solution is neutralized with chalk; calcium phenylsulphite,
which is soluble, and sulphate, which is insoluble, are formed.
The calcium phenylsulphite is converted into sodium phenyl-
sulphite by double decomposition with sodium carbonate, and
after evaporation and desiccation, the sodium phenylsulphite is
fused in a silver crucible with an excess of potassium hydrate.
The mass is exhausted with water, and the alkaline solution is
decomposed by hydrochloric acid. The phenol separates and
is dried and purified by distillation (Dusart, Wurtz, Kekulé).
The decomposition of sodium or potassium phenylsulphite
is expressed in the following equation:
C6H5.SO³K + KOH
Potassium phenylsulphite.
C6H5OH + K2SO³
Potassium sulphite.
Phenol.
There is another very simple synthesis of phenol. In pres-
ence of aluminium chloride, benzol absorbs oxygen directly and
phenol is formed.
C6H6 + 0 = C6H6O
This reaction is one of the most unexpected and most in-
teresting applications of a general method of synthesis discov-
ered by Friedel and Crafts (see page 619).
Properties of Phenol.-Phenol is a solid, crystallizing in
long, colorless needles, fusible at 35°. It has a peculiar, char-
acteristic odor, and an acrid, burning taste. It boils at 186°.
It is slightly soluble in water, but dissolves readily in concen-
trated acetic acid. It possesses antiseptic properties.
Although phenol is neutral to litmus-paper, it forms definite
combinations with the alkalies. When it is mixed with a very
TRINITROPHENOL.
607
:
concentrated solution of potassium hydrate, a crystalline mass
is obtained which constitutes potassium phenate, CH³.OK.
Phosphorus perchloride converts it into phenyl chloride,
identical with monochlorobenzol.
CH³.OH + PC1³
Phenol.
CH³C + POC³ + HCl
Phenyl chloride.
The following remarkable reaction of phenol was first noticed
by Reimer and Tiemann. When it is heated with chloroform
and an excess of sodium hydrate, in the proportion of one
molecule each of phenol and chloroform and four molecules of
alkali, it is converted into salicylic aldehyde (salicyl hydride).
CH³.ONa+3NaOH + CHC¹³=C*H³O³Na+3NaCl + 2H²O
Sodium salicylite.
Sodium
phenate.
The compound C'H³O'Na is the sodium compound of sali-
cylic aldehyde, into which it is converted by hydrochloric acid.
TRINITROPHENOL.
(PICRIC ACID.)
C6H2(NO2)3.OH
When phenol is boiled with concentrated nitric acid, it is
converted into trinitrophenol.
C6H5OH + 3HNO3 = 3H20+ CH2(NO2)3.OH
CH³.OH
This body has long been known, and is generally called picric
acid. It deposits from boiling water in lemon-yellow, crystal-
line plates, only slightly soluble in cold water. Its taste is very
bitter. With the bases it forms crystallizable salts, which deto-
nate with violence when heated.
Potassium picrate, CH²(NO2)3.OK, crystallizes in long, yel-
low needles, soluble in 14 parts of boiling water and in 250
parts at 15°. It explodes violently when heated.
Picramic Acid. When a current of hydrogen sulphide is
passed through an alcoholic solution of pieric acid saturated
with ammonia, sulphur separates and the picric acid is con-
verted into pieramic acid (A. Girard).
CII²(NO²)³.OH + 3H²S = 2H2O + S³ + C¤H²(NO²)²(NH²)OH
Picric acid.
Picramic acid.
The hydrogen sulphide partially reduces the picric acid, and
one of the three groups (NO2) is thus converted into a group
608
ELEMENTS OF MODERN CHEMISTRY.
(NH2). Picramic acid is dinitro-amido-phenol, that is, phenol
in which two atoms of hydrogen are replaced by two groups
(NO²), and a third atom of hydrogen by the group NH".
When acetic acid is added to a hot aqueous solution of the
ammonium salt of picramic acid, the picramic acid is deposited
in fine red needles.
AURIN (ROSOLIC ACIDS).
When 1 part of phenol is heated with 1 part of oxalic
acid and 2 parts of sulphuric acid, it is converted into a color-
ing-matter, which was first described under the name rosolic
acid, or coralline-yellow. The same body or analogous bodies
may be obtained by means of the rosanilines (see farther on).
Indeed, it has been recognized that there are several homolo-
gous bodies having the properties and the constitution of roso-
lic acid.
Rosolic acid made from pure phenol contains C¹⁹H¹¹O³, and
is called aurin (Dale and Schorlemmer). It occurs in very
brilliant, red, anorthic prisms having a blue or green reflection.
It corresponds to a rosaniline, CH"(NH2)" (pararosaniline).
To ordinary rosaniline and its superior homologue, chrysoto-
luidine (see farther on), correspond two other rosolic acids, supe-
rior homologues of aurin. The following formulæ indicate the
relations which exist between these bodies:
C19H¹¹ (OH)3
Aurin.
C120 H13(OH)3
Rosolic acid.
C19 H¹¹(NH2)3
Inferior homologue of rosaniline.
CH1(NH)*
3
Ordinary rosaniline.
Aurin is used in dyeing. When it is heated to 180° with
an alcoholic solution of ammonia, it is converted into a bright-
red coloring matter, noticed by Persoz, and employed in dyeing
under the name coralline-red.
ANILINE, OR PHENYLAMINE.
C6H7N CH5.NH2
Aniline was discovered by Unverdorben among the products
of the distillation of indigo, and was extracted from coal-tar by
Runge. It is now prepared artificially by a process discovered
by Zinin. This process consists in converting benzol into ni-
ANILIDES.
609
trobenzol, and subjecting the latter to the action of reducing
agents (see nitrobenzol).
Iron and acetic acid are advantageously used to accomplish
this reduction (Béchamp).
Aniline is a colorless, mobile, highly-refracting liquid, having
a peculiar, unpleasant smell, and an acrid, burning taste. It
is a little heavier than water. It boils at 184.8°. When ex-
posed to the air, it becomes brown and is eventually resinified.
Aniline is almost insoluble in water, but mixes in all pro-
portions with alcohol, ether, and the fatty and volatile oils.
It does not restore the blue color to reddened litmus-paper,
but nevertheless possesses the character of an alkaloid, for it
forms well-defined salts with the acids.
Reactions.-1. If a nitrate and sulphuric acid be added to
aniline, a red color is produced.
2. If a few drops of aniline be poured into an excess of sul-
phuric acid, and a small quantity of potassium dichromate be
added, a magnificent blue color is developed, which changes to
violet on the addition of water.
3. A solution of calcium hypochlorite (chloride of lime)
added to aniline produces a beautiful violet tint.
4. When a solution of an aniline salt is heated with cupric
chlorate, an intense black color is developed (Ch. Lauth).
These reactions are applied in the arts in the preparation of
coloring matters of incomparable richness. The most impor-
tant of these matters is rosaniline, or fuchsine, which will be
described farther on.
Salts of Aniline. These are obtained by saturating aniline
by the acids.
Aniline hydrochloride, CH'N.HCl, forms colorless needles,
which are fusible, and can be distilled without alteration; they
are very soluble in water and in alcohol. Platinic chloride pre-
cipitates from the solution fine yellow needles of a chloro-plati-
nate, (CH'N.HCl)2PtCH.
Aniline oxalate, (C'H¹N)²C²H²O*, crystallizes from water in
hard, thick prisms. When heated, it loses the elements of
water, and is converted into oxanilide.
ANILIDES.
By the action of heat, the aniline salts lose the elements of
water, and form compounds analogous to the amides, and which
2A*
610
ELEMENTS OF MODERN CHEMISTRY.
Gerhardt named anilides. When aniline oxalate is heated, it
is converted into oxanilide, which is no other than oxamide
in which two atoms of hydrogen are replaced by two phenyl
groups, (C6H5).
C202
H2 N2
H2
Oxamide.
C2H30
HN
H
Acetamide.
C202
(C6H5)2 N2
H2
Phenyl oxamide (oxanilide).
C2H3O
C6H5 N
H
Phenylacetamide (acetanilide.)
DIAZOBENZOL COMPOUNDS.
Nitrous acid exerts an energetic action upon aniline and the
analogous bases; it is indicated here because it presents a great
generality and gives rise to remarkable bodies, which are called
diazo-compounds.
When a current of nitrous gas is passed into a saturated so-
lution of an aniline salt, such as the nitrate, crystals of diazo-
benzol nitrate are deposited.
CH'N.HNO3 +
Aniline nitrate.
+ HNO²
2H2O + C°H³N².NO³
Diazobenzol nitrate.
This body is formed by the substitution of one atom of nitro-
gen for three atoms of hydrogen in aniline nitrate.
C6H5-NH2.HNO3 aniline nitrate.
C6H5-N=N-(NO³) diazobenzol nitrate.
It forms long, colorless prisms, very soluble in water, slightly
soluble in alcohol, and insoluble in ether. It explodes violently
by heat or by percussion. This salt and its congeners present
two remarkable reactions. When heated with water, they dis-
engage nitrogen, and are converted into phenols.
C6H5N².NO³ + H2O CH³.OH + N² + HNO³
When they are boiled with absolute alcohol, they are reduced
to hydrocarbons, nitrogen being disengaged and the alcohol
being transformed into aldehyde.
CH³N².HSO¹ + C²H³O = C²H¹O + CHε + N² + H²SO¹
Diazobenzol sulphate.
Aldehyde. Benzol.
When aniline is added to an aqueous solution of diazobenzol
ROSANILINE.
611
nitrate, a diazo-compound is obtained which is more complex
than the preceding and is called diazoamidobenzol.
CH*N(NO3) + NH*.CH = CH –N_NH.CH +HNO
Diazobenzol nitrate.
Aniline.
Diazoamidobenzol.
The same body is formed when a current of nitrogen tri-
oxide is passed into a cooled alcoholic solution of aniline. It
forms brilliant, golden-yellow scales, fusible at 91°. It ex-
plodes at a higher temperature.
ROSANILINE AND ITS DERIVATIVES.
C20H19N3
This magnificent red coloring matter is obtained by heating
aniline to 150 or 160° with arsenic acid, which acts in this case
as an oxidizing agent. The solid product of the reaction is
dissolved in water, and the filtered solution is treated with solu-
tion of sodium hydrate; the rosaniline which was combined
with arsenic acid is precipitated. It is then dissolved in acetic
or hydrochloric acid, and the salt so formed is crystallized.
It separates in magnificent crystals which present a green re-
flection, like the scales of cantharides, and dissolve in alcohol
with a rich purple color.
The rosaniline formed in this reaction results from the oxida-
tion of the aniline, and toluidine (see farther on), which always
exists in commercial aniline.
CHỒN + 2CH°N + O*
Aniline.
Toluidine.
C20H19N3 + 3H20
Rosaniline.
In the preparation of rosaniline, arsenic acid, the use of
which is dangerous, has been replaced by another oxidizing
agent, which is nitrobenzol. The latter acts by virtue of the
group NO2, which it contains (J. Persoz). This improvement
has been introduced in France by Coupier, and in Germany by
Meister, Lucius, Brüning.
Properties of Rosaniline. The methods of preparation
just indicated furnish the salts of rosaniline, such as the hydro-
chloride, which is the rich coloring matter known as fuchsine.
The free base is obtained by treating a hot, saturated solution
of the hydrochloride with an excess of soda. The rosaniline
separates as an almost colorless, crystalline precipitate. It is a
triacid base which requires three molecules of hydrochloric
612
ELEMENTS OF MODERN CHEMISTRY.
acid for its saturation. It is curious that free rosaniline is
colorless and occurs in small crystals.
120
The monohydrochloride of rosaniline, CH9N3. HCl (fuch-
sine), forms dark-colored, rhombic tables, having a splendid
green reflection. It is but slightly soluble in water, but dis-
solves readily in alcohol, forming an intense purple solution.
The trihydrochloride, C20HN3.3HCl, forms yellow-brown
needles which lose hydrochloric acid when heated or when dis-
solved in water.
Rosaniline and its salts present two important reactions:
1. When a salt of rosaniline is treated with reducing agents,
such as nascent hydrogen (zinc and hydrochloric acid), the
base fixes two atoms of hydrogen and is converted into leu-
caniline, C20H²¹N³, a white powder slightly soluble in water.
211
2. By the action of nitrogen trioxide, rosaniline is converted
into a diazo-derivative which yields rosolic acid when boiled
with water (pages 608 and 610).
Constitution of Rosaniline.-According to Hofmann, the
formula C20H19N³ represents the composition of rosaniline. It
is exact, but it has been recognized that the products known
under the name fuchsine contain several isomerides (Rosen-
stiehl), and it is known, besides, that there are several homo-
logues of rosaniline. Without dwelling on the subject, we may
mention the following bodies:
C191117N3 pararosaniline (Fischer).
C20H19N3 rosaniline.
C21121N3 chrysotoluidine.
There exist also corresponding leucanilines containing two
more atoms of hydrogen.
Hofmann has attributed to the rosaniline C20H19N3 the con-
stitution expressed by the formula
(CH)"
2(CH)" N³
H³
According to him, it is a triamine, containing at the same
time a diatomic group phenylene, CH, and two diatomic
groups C'H.
Recent researches tend to modify this view. E. and O.
Fischer consider that this rosaniline is a triamine, C20II13
(NH2), derived from a hydrocarbon C20H16, and that para-
ROSANILINE.
613
rosaniline is a triamine, C¹H¹¹(NH2)³, derived from a hydro-
carbon, C¹¹H¹. By subjecting the corresponding leucanilines
to the action of nitrous anhydride, and reducing the diazo-
compounds thus formed by alcohol, these chemists obtained
the hydrocarbons C20H18 and C9H16, which were again con-
verted into leucanilines, and then, by oxidation of the latter,
into rosanilines.
We may add that the hydrocarbon C9H16, which is solid
and fusible at 93°, is triphenylmethane, that is, marsh-gas, in
which three atoms of hydrogen are replaced by three phenyl
groups.
CH⭑
Methane.
CH(CH3)3
Triphenylmethane.
Coloring Matters derived from Rosaniline.-When rosan-
iline is heated with ethyl iodide, three atoms of hydrogen are
replaced by three ethyl groups, and this triethyl-rosaniline
yields with the acids a magnificent violet color, known as Hof-
mann's violet.
Triphenyl-rosaniline, in which three atoms of hydrogen are
replaced by three phenyl groups, C'H³, is formed when rosani-
line is heated with an excess of aniline. This reaction, in
which ammonia is disengaged, was discovered by Girard and
de Laire.
C20H19N3+3C6H5.NH²
Rosaniline.
Aniline.
16
C¹²ºH¹º(CH³)³N³ + 3NH³
Triphenyl-rosaniline.
The hydrochloride of triphenyl-rosaniline is of a magnificent
blue color, and is known as Lyons blue (Ch. Girard and de
Laire). The following formulæ show the interesting relations
which exist between rosaniline and its ethyl and phenyl deriv-
atives:
C20H 19N3
Rosaniline.
C20H16 (C2H5)³N³
Triethyl-rosaniline.
(Base of Hofmann's violet.)
C20H16 (C6H5)³N³
Triphenyl-rosaniline.
(Base of Lyons blue.)
We may mention among the derivatives of rosaniline, Paris
violet and the aniline greens, particularly the beautiful color-
ing matter known as night-green, because it retains its rich
green tint in artificial light.
Paris violet, which has been for some years manufactured
by Poirrier, is a splendid color, produced by the oxidation of
methylaniline or dimethylaniline.
52
614
ELEMENTS OF MODERN CHEMISTRY.
C6H5
CH3N
H
C6H5
Methylaniline.
CH³N
CH3
Dimethylaniline.
Ch. Lauth realizes this oxidation, or rather dehydrogena-
tion, by heating methylaniline with cupric chloride. The
reaction is complex, and, according to Hofmann and Martius,
gives rise to trimethyl-rosaniline.
When heated with methyl chloride, the base of Paris violet
fixes two molecules of that compound, forming a combination
of trimethyl-rosaniline and methyl chloride. This combination
constitutes night-green.
C20 H16(CH3)3N³. (CH³CI)
Dichloromethylate of trimethyl-rosaniline
(night-green).
DIPHENYLAMINE.
C12H11N
C6H5
C6H5N
H
This body is derived from ammonia by the substitution of
two phenyl groups for two atoms of hydrogen. It is formed
in various reactions, of which the most interesting was discov-
ered by Girard and de Laire. It consists in heating aniline
hydrochloride to 256° with aniline. Ammonia is disengaged,
and diphenylamine hydrochloride is formed.
C6H5
C6H5
C6H5
HN.HCI +
II N
H
C6H5 N.HCl + NII3
H
H
Free diphenylamine forms crystals fusible at 54°. It boils.
at 310°. It is insoluble in water, but dissolves in alcohol,
ether, benzol, and petroleum. Its odor recalls that of oil of
rose.
When heated with a mixture of oxalic and sulphuric acids,
it yields a splendid blue color, soluble in water, and known as
diphenylamine blue (Girard and de Laire).
OXYPHENOLS.
C6H6O2
Three isomeric bodies having the composition CHO²
4
OH
CV6 H+ OH
are known; they are derived from benzol by the
substitution of two hydroxyl groups for two atoms of hydro-
RESORCIN.
615
gen.
These three bodies are oxyphenol, or pyrocatechin, resor-
cin, and hydroquinone.
tem.
Pyrocatechin. This body is so named because it was first
obtained by the destructive distillation of caoutchouc. It is
also produced by the distillation of gum kino and various tan-
nins which produce a green color with ferric salts. Pyroca-
techin is a solid body, very soluble in water and alcohol, very
slightly soluble in ether; it crystallizes from its aqueous solu-
tion in rectangular prisms, belonging to the orthorhombic sys-
It melts at 111.8°, and sublimes below that temperature
in brilliant, colorless plates. It boils between 240 and 245°.
Its odor is strong and excites sneezing. It has the character
of an acid, like phenol itself. It dissolves in the alkalies and
in the alkaline carbonates. When exposed to the air, these
solutions become colored, first green, then brown and black.
An aqueous solution of pyrocatechin produces a deep-green
color with ferric chloride, which changes to dark-red on the
addition of an alkali.
Resorcin. This body, which is the homologue of orcin,
CH8O2, is formed when certain gums, such as galbanum,
asafœtida, gum ammoniac, sagapenum, etc., are fused with
potassium hydrate (Hlasiwetz and Barth). It is extracted
from the fused mass by dissolving the latter in water, super-
saturating with sulphuric acid, filtering, and agitating the fil-
tered solution with ether, which dissolves the resorcin. After
having driven off the ether on a water-bath, a residue is ob-
tained which is distilled: the resorcin sublimes and condenses
in radiated crystals.
Oppenheim and Vogt obtained resorcin by fusing chloro-
phenylsulphurous acid with potassium hydrate. The former
body is obtained when chlorobenzol is treated with sulphuric
acid.
C6H5C1
Chlorobenzol.
+ H2SO4
H20
+
SOзH
C6 H+ Cl
Chlorophenyl-
sulphurous acid,
C6H4
SO³K
Cl
+ 2KOH
KCl + K2SO3 + C©H+ {
OHI
Potassium chlorophenyl-
он
Resorcin.
sulphite.
Resorcin forms colorless, prismatic or tabular crystals. It
melts at 110°, and boils at 271°. It is very soluble in water,
alcohol, and ether.
616
ELEMENTS OF MODERN CHEMISTRY.
QUINONE AND HYDROQUINONE.
Quinone, CH¹O'.-This remarkable body, discovered by
Woskresensky, is a product of the oxidation of quinic acid,
which exists in cinchona bark. It may be obtained by dis-
tilling that acid with a mixture of manganese dioxide and
sulphuric acid. The mass swells up and disengages vapors of
quinone, which condense in the receiver in brilliant, golden-
yellow needles. They are pressed between folds of filter-paper
and purified by resublimation.
Quinone crystallizes in long, brilliant, transparent needles of
a golden-yellow color. It is very soluble in cold water, and
more soluble in alcohol and ether. It melts at 115.7° to a
yellow liquid, which at 115.2° solidifies to a crystalline mass.
It sublimes at ordinary temperatures, emitting pungent vapors
which excite tears.
Chlorine converts it into a trichloro-derivative, CHCP³O²,
crystallizable in small, yellow prisms, fusible at 164-166°.
When treated with a mixture of potassium chlorate and
hydrochloric acid, quinone is converted into tetrachloroquinone,
CCl¹O², better known as chloraline. This name was given by
Erdmann, who first obtained this body by the action of chlorine
on indigo, of which the Portuguese name is anil. The same
body is formed by the action of a mixture of potassium chlorate
and hydrochloric acid on a great number of aromatic com-
pounds, such as phenol, picric acid, salicylic acid, salicin, isatine,
etc. Tetrachloroquinone forms pale-yellow scales, having a
pearly, metallic lustre. When gently heated, it sublimes with-
out fusing, and leaves no residue. It is insoluble in water and
almost insoluble in cold alcohol, but dissolves in boiling alcohol
and separates on cooling in golden-yellow scales.
CHO².-
Hydroquinone, C6H6O2. This body is formed by the action
of reducing agents, such as nascent hydrogen, hydriodic acid,
or sulphurous acid, on quinone.
C6H4O2 + H2²
C6H6O2
Wöhler, who discovered it, found it also among the products.
of the dry distillation of quinic acid.
Hydroquinone crystallizes in beautiful, transparent, and col-
orless, right rhombic prisms. It has no odor; its taste is
sweetish. It dissolves in 17 parts of water at 15°, and is very
QUINONE AND HYDROQUINONE.
617
soluble in alcohol and ether. It melts at 177.5°, and solidifies
at 165°. When gently heated, it sublimes in brilliant plates,
like those of sublimed benzoic acid. It partially decomposes
when abruptly heated. When its vapor is passed through a
tube heated to dull redness, it breaks up into quinone and
hydrogen. Various oxidizing agents, such as chlorine, ferric
chloride, nitric acid, silver nitrate, and potassium dichromate,
transform it into a substance which deposits in magnificent
green needles, having a metallic reflection. It is quinhydrone
or green hydroquinone, CHO', a combination of quinone and
hydroquinone.
Constitution of Quinone and Hydroquinone.-According
to Graebe, these bodies are allied to benzol, from which the first
is derived by the substitution of two atoms of oxygen for two
atoms of hydrogen; but as the two atoms of oxygen represent
four atomicities, of which two only are employed in replacing
H² in benzol, the other two serve to bind together the two
atoms of oxygen. The couple (O′-0″)″ can indeed play the
part of a diatomic group. In the formation of hydroquinone,
these atoms of oxygen separate from each other and cach fixes
one atom of hydrogen, so that two hydroxyl groups are formed
and substituted each for one atom of hydrogen in benzol. The
following formulæ express these relations:
C6H6
Benzol.
C6H+
Quinone.
<<< !
8
он
C6H*<OH
Hydroquinone.
This view is generally adopted, but it is not established with
certainty. It may be that each atom of oxygen is united by
both of its atomicities to a carbon atom. In this case it would
be necessary to admit that the constitution of the benzol nucleus
is modified, in that the double bond uniting two carbon atoms
would be resolved into one.
H
H
H
HC
"1
CH
HC
〃
HỒ CH
HC
C-O
[{
HC
or
C=0
C-O
H
C
11
но
:0
C
H
C
II
Benzol.
II
Quinone.
Quinone.
(?)
Bodies anologous to quinone and hydroquinone have been
obtained from naphthalene and anthracene.
52*
618
ELEMENTS OF MODERN CHEMISTRY.
PHLOROGLUCIN.
C6H6O3 = C6H³(OH)³
Phloroglucin and its isomeride pyrogallol are trioxyphenols,
and represent benzol in which three atoms of hydrogen are
replaced by three hydroxyl groups. The relations between
phloroglucin, oxyphenol, and phenol, are the same as those
between glycerin, propylglycol, and propyl alcohol.
C3H7.OH
Propyl alcohol.
C6H5.0H
Phenol.
OH
C3H6
{
16OH
он
он
C3H5OH
он
Propylglycol.
Glycerin.
он
C6H4
{
он
C6H3OH
он
он
Oxyphenol.
Phloroglucin.
Phloroglucin was discovered by Hlasiwetz, who obtained it
by heating phloretin (page 589) with a very concentrated solu-
tion of potassa. It is also formed in many other reactions,
especially when gum-kino, gamboge, and dragon's-blood are
fused with potassium hydrate.
Phloroglucin crystallizes in hard, rhombic prisms, having a
very sweet taste. It is quite soluble in water, alcohol, and
ether. Its aqueous solution is neutral. Its ethereal solution,
evaporated upon a microscope slide, deposits prisms in tangled,
tree-like forms which are very characteristic.
The crystals deposited from ether are anhydrous, while those
formed in water contain two molecules of water of crystalliza-
tion, which they lose at 100°. The dry crystals melt at 220°.
TOLUOL AND ITS DERIVATIVES.
Toluol is a homologue of benzol. It was discovered in 1837
by Pelletier and Walter; H. Deville has obtained it by distil-
ling balsam of Tolu; hence its name. It exists in coal-tar,
and may be separated from that body, like benzol, by fractional
distillation. Its density at 0° is 0.882. It boils at 111°. It
is methyl-phenyl, or methyl benzol, and has been obtained by
synthesis by heating a mixture of methyl iodide and monobro-
mobenzol with sodium (Fittig and Tollens).
C6H5Br + CH³I + 2Na
Monobromobenzol.
NaI + NaBr + CH–CH3
Methyl-phenyl.
TOLUOL.
619
A method of synthesis of toluol, which by the generality of
its applications is one of the most fecund in chemistry, is due
to Friedel and Crafts. It consists in the reaction of methyl
chloride on benzol in presence of aluminium chloride. Toluol is
formed, and hydrochloric acid is disengaged. It is probable that
the aluminium chloride first acts on the benzol, disengaging
hydrochloric acid and forming a phenyl derivative of aluminium
chloride, which derivative is continually formed and continually
decomposed by the methyl chloride. The cycle of reactions
would then be represented by the following two equations:
C6H6+A12C16 AP²C (CH³) + HCl
Al²C (CH) + CH³CI = CH³(CH³) + Al²C16
We
e may add that the toluol thus formed may react with an
excess of methyl chloride, forming hydrochloric acid and dime-
thyl benzol (xylol), which in its turn may react upon an excess
of methyl chloride. It is thus seen that the methylation of
benzol does not stop with the first substitution compound, and
that the nature of the products formed depends upon the pro-
portions of the bodies which react. Friedel and Crafts have
thus succeeded in introducing six methyl groups into benzol,
and have made the synthesis of hexamethylbenzol.
CH+6CH³Cl = 6HCl + C(CH3) 6
Hexamethylbenzol.
When toluol is boiled with dilute nitric acid, or with a solu-
tion of chromic acid, it is transformed into benzoic acid.
Substitution Products of Toluol.-These compounds are
numerous, and present various isomerisms, of which we will
consider the principles.
When chlorine acts upon toluol,
C6H5
"
CH³
one or more atoms
of hydrogen may be removed and replaced by as many atoms
of chlorine. The most simple of the products thus formed is
the compound C'H'Cl, which results from the substitution of
one atom of chlorine for one atom of hydrogen in toluol, C'H.
But this substitution may take place in the benzol nucleus
CH³, or in the lateral chain CH³, and two isomeric bodies are
thus formed, monochlorotoluol and benzyl chloride.
C6H⭑CI
CH3
Monochlorotoluols.
C6H5
CH2CI
Benzyl chloride.
620
ELEMENTS OF MODERN CHEMISTRY.
CH³
Monochlorotoluol, C©H*<Cl is a di-substituted derivative
>
of benzol; it may consequently exist in three isomeric modifi-
cations, as has already been explained (page 594).
It is thus seen that there are four different bodies derived
from toluol by the substitution of one atom of chlorine for one
of hydrogen, namely, benzyl chloride and three monochloro-
toluols.
The following table includes a number of toluol derivatives :
C6 H+CI
CH*(NHỎ) CH*(OH)
сиз
CH3
сиз
Monochlo-
Toluidine.
Cresol.
rotoluol.
C6H5
C6H5
C6H5
C6H5
CH¹(OH)
CH¹(OH)
сно
CO.OH
Salicyl
hydride.
C6H5
Salicylic acid.
CH2C1
CH2(NH2) CH2OH
сно
CO.OH
Benzyl
Benzyla-
Benzyl
chloride.
mine.
alcohol.
Benzyl
aldehyde.
Benzoic acid.
Among these compounds, those placed in the same vertical
line present isomerisms easily understood from the formulæ,
which express their constitutions and show the atomic group-
ings.
Those bodies in the first horizontal series constitute di-sub-
stituted compounds of benzol.
C6H4 NH2
CH3
Toluidines.
C6H4OH
Cresols.
CH3
CHO
C6H
он
Salicyl hydride.
C6H4
он
Salicylic acid.
CO.OH
Hence they may exist in three different isomeric modifica-
tions, and consequently there are four isomerides of each of
these derivatives of toluol, excepting salicylic acid, just as for
monochlorotoluol.
Chloro-Derivatives of Toluol.-Benzyl chloride, CH5-
CH'Cl, is formed when chlorine is passed into boiling toluol.
It is a colorless liquid, having an irritating odor, and boiling
at 176°.
The monochlorotoluols are formed by the action of chlorine
on cold toluol. Ortho- and metachlorotoluol are liquids, boil-
ing between 156 and 157° Parachlorotoluol boils at 160.5°,
and below 0° solidifies to a mass which melts at 6.5°.
Nitrotoluols.-Monohydrated nitric acid attacks toluol and
converts it into nitrotoluol, C'H'(NO²), and dinitrotoluols,
according to the duration of the reaction. There are three
nitrotoluols, CH*<NO²
CHCH
CRESOLS ORCIN.
621
Orthonitrotoluol, a yellow liquid, boiling between 222 and
223°.
Metanitrotoluol, crystals, fusible at 16°. Boils at 230-231°.
Paranitrotoluol, almost colorless prisms, fusible at 54°, and
boiling at 236°.
Dinitrotoluol, CH³(NO2)2CH³, is formed when toluol is
treated with a mixture of nitric and sulphuric acids. Long
needles, almost colorless, fusible at 70.50. An isomeride is
known, fusible at 60°.
CRESOLS.
C7H8O
There are three cresols, two solid and one liquid. They
may be formed artificially by treating toluol with sulphuric acid,
according to the process indicated on page 606; but in this
reaction several isomeric sulphoconjugated acids are formed,
and when decomposed by potassium hydrate, they yield differ-
ent cresols.
The liquid cresol discovered by Fairlie, and extracted from
wood-tar by Duclos, is a colorless liquid, having an odor like
that of phenol. It boils at 189-190°. It appears to be a
mixture.
Orthocresol is a crystalline mass, fusible at 31°, and boiling
at 185-186°.
Metacresol is liquid.
Paracresol forms colorless prisms, fusible at 34.5°. It boils
at 201° (A. Wurtz).
ORCIN.
C7H802
This body is an oxycresol. It was discovered by Robiquet
in 1829, and is obtained, at the same time as erythrite, by
decomposing erythrin by slaked lime at 150°.
The orcin is deposited first in beautiful crystals from the
solution which contains both substances, and it is purified by
recrystallization. It forms colorless, hexagonal prisms, con-
taining one molecule of water of crystallization. It melts at
58°, losing its water, and the anhydrous orcin boils at 290°.
The crystals of orcin become rose-colored in the air. When
ammonia is added to their aqueous solution and the liquid is
622
ELEMENTS OF MODERN CHEMISTRY.
exposed to the air, it absorbs oxygen and assumes first a violet
color and afterwards a brown. A nitrogenized body is formed
which is known as orcein, and constitutes the coloring principle
of the orchil of commerce.
The synthesis of orcin has been made by the action of fused
potassium hydrate on the sulphoconjugated acid of mono-
chlorotoluol (cresyl chloride, CH+CI.CH). The chlorine and
the group, SO H, of this compound are thus replaced by two
groups OH (Vogt and Henninger).
Cl
C6H³ SO³ K + 2KOH
CH3
Potassium chlorocresyl-
=
OH
SO³K² + KCI + C6H³ OH
CH3
Orcin.
sulphite.
TOLUIDINES.
C7H9N
=
C6H4(NH2)-CH3
Paratoluidine.-Solid toluidine, which is paratoluidine, was
discovered by Hofmann and Muspratt in 1848. They obtained
it by the reduction of paranitrotoluol by ammonium sulphy-
drate. This reduction may also be accomplished by iron and
acetic acid, or by tin and hydrochloric acid.
C'H'(NO) + 3H2 C'H'(NH) + 2H2O
Nitrotoluol.
Toluidine.
An interesting method of formation of paratoluidine was dis-
covered by Hofmann and Martius. When methylaniline hydro-
chloride is heated to 350° under pressure, paratoluidine hydro-
chloride is formed. The methyl group which is united to the
nitrogen of the former base is then transposed and exchanged
for an atom of hydrogen of the phenyl group.
N
C6H5
CH3
C6H4-CII³
N
-H
H
Toluidine.
H
Methylaniline.
Paratoluidine is a solid heavier than water.
It crystallizes
from its dilute alcoholic solution in large plates. It melts at
45°, and boils at 198°. It is almost insoluble in water, but
very soluble in alcohol and in ether.
Toluidine exists nearly always in commercial aniline. It is
important and necessary for the preparation of certain aniline.
colors.
Orthotoluidine was discovered by Rosenstiehl in commercial
BENZYL ALCOHOL.
623
toluidine, which is a mixture of para- and orthotoluidine. It is
formed by the reduction of orthonitrotoluol by nascent hy-
drogen. It is liquid and does not solidify at -20°. It boils
at 199.5°.
Metatoluidine-A colorless liquid, boiling at 197°. Density
at 25°, 0.998.
BENZYL ALCOHOL.
C7H8O C6H5-CH2.OH
Cannizzaro obtained this body by heating oil of bitter
almonds with an alcoholic solution of potassium hydrate.
2C'HO + KOH
Benzyl aldehyde.
KC'H³O² + C'HO
Potassium benzoate. Benzyl alcohol.
Toluol may be converted into benzyl alcohol. It is boiled
in a current of chlorine, and benzyl chloride is thus formed,
C'H'CI.* This chloride may be transformed into benzyl
alcohol by heating it with potassium acetate and decomposing
the benzyl acetate so formed by potassa.
CHCI +
Benzyl chloride.
C'H.C2H3O2
Benzyl acetate.
KCH³O²
+ KOH
C2H3O2.C'H + KCl
Benzyl acetate.
KC2H302
+
C'H'.OH
Benzyl alcohol.
Benzyl alcohol, or benzyl hydrate, is a colorless, oily liquid,
having a faint but agreeable odor. It boils at 207°. Density
at 0°, 1.0628.
When heated with nitric acid, it is converted into benzyl
aldehyde (oil of bitter almonds).
C'H³O + O H2O + C'HO
Chromic acid oxidizes it to benzoic acid.
C'H³O +02 HO + CHO
The relations between benzyl alcohol, benzyl aldehyde, and
benzoic acid are the same as those between alcohol, aldehyde,
and acetic acid.
CH3-CH2.OH alcohol.
CH3-CHO aldehyde.
CH3-CO2H acetic acid.
C6115-CH2.OH benzyl alcohol.
C6H5_CHO
C6H5-CO2H
benzyl aldehyde.
benzoic acid.
When chlorine is passed into cold toluol, benzyl chloride is not formed,
but monochlorotoluol (page 620).
624
ELEMENTS OF MODERN CHEMISTRY.
Benzyl Compounds.-Benzyl chloride, C'H'CI CH5-
CH2Cl, is formed, as has already been remarked, when chlorine
is passed into boiling toluol. It is also formed by the action
of hydrochloric acid on benzyl alcohol by the aid of heat. It
is a colorless liquid having an irritating odor. It boils at
176°.
Benzylamine, CH-CH'.NH.-This body is formed by the
action of nascent hydrogen on benzonitrile (phenyl cyanide),
which thus fixes four atoms of hydrogen. It is also formed
in small quantity, together with dibenzylamine and tribenzyl-
amine, when benzyl chloride is heated with alcoholic ammonia.
It is a limpid liquid, boiling at 185°, and miscible with water,
alcohol, and ether. Density, 0.99 at 14°.
Tribenzylamine, (CH5.CH²)N.—This is formed in abun-
dance by the action of a hot alcoholic solution of ammonia on
benzyl chloride. It crystallizes in beautiful, colorless needles.
or plates, fusible at 91°. It is insoluble in water, slightly
soluble in cold alcohol, very soluble in hot alcohol and in ether.
BENZYL ALDEHYDE.
CH6O =
-
CH5_CHO
This body, also called benzoyl hydride, exists in the essential
oil of bitter almonds, mixed with hydrocyanic acid, both sub-
stances being formed by the action of emulsin and water on
amygdalin (page 587).
Benzyl aldehyde is a colorless, strongly-refracting liquid, hav-
ing a pleasant odor and a pungent, aromatic taste. It boils at
179.5°.
When its vapor is passed through a porcelain tube filled with
pumice-stone and heated to redness, benzyl aldehyde breaks up
into benzol and carbon monoxide.
C'HO CO + C6H6
When exposed to air and light, it absorbs oxygen, and is con-
verted into benzoic acid.
C'HεO +0
C'II6O²
Benzoic acid.
Nascent hydrogen, produced by the action of water on
BENZOYL CHLORIDE.
625
sodium amalgam, transforms benzyl aldehyde into benzyl alco-
hol (Friedel).
C'HO + H² C'H'.OH.
Chlorine and bromine convert it into chloride and bromide
of benzoyl; hence the name benzoyl hydride.
C'HO.H + Cl²
Benzyl aldehyde.
HCI + C'H³O.Cl
Benzoyl chloride.
When crude oil of bitter almonds containing hydrocyanic
acid is mixed with alcoholic potassium hydrate, or when the
pure oil is mixed with an alcoholic solution of potassium cya-
nide, the benzyl aldehyde is polymerized and converted into a
solid body, which is benzoin, C¹¹¹²02. The latter body crystal-
lizes in brilliant, colorless prisms, fusible at 133-134°. It is
but slightly soluble in water and cold alcohol, very soluble in
boiling alcohol.
Benzoyl Chloride, CH-COCI.-This body is also formed
by the action of phosphorus pentachloride on benzoic acid or a
dry benzoate. It is a colorless, highly-refractive liquid, having
a peculiar, irritating odor. It boils at 190°. Water decom-
poses it into benzoic and hydrochloric acids.
C'H³O.Cl + H2O CH3O.OH + HC
Ammonia converts it into benzamide.
C'H³.OCI + NH³ C'H³O.NH² + HCl
Benzamide.
Benzoyl chloride may exchange its chlorine for other ele-
ments. When it is distilled with potassium iodide, potassium
chloride and benzoyl iodide are formed. Liebig and Wöhler,
who discovered these important reactions, prepared in the
same manner, by double decomposition, benzoyl sulphide and
benzoyl cyanide. These experiments are celebrated; they
were the starting-point of the benzoyl theory, which marked
an important progress in the development of the theory of
radicals. The following formulæ indicate the principal benzoyl
combinations:
C7H50.H benzoyl hydride (oil of bitter almonds).
C7H50.Cl benzoyl chloride.
C7H50.I benzoyl iodide.
(C7H50)2S benzoyl sulphide.
CH50.0II benzoyl hydrate (benzoic acid).
C7H50.NH2 benzamide.
2B
53
626
ELEMENTS OF MODERN CHEMISTRY.
BENZOIC ACID.
C7H6O2
C6H5-CO2H
Preparation. This acid may be obtained from gum benzoin.
That resin is placed in a flat dish over the top of which a sheet
of tissue-paper, or light filter-paper is glued (Fig. 131). This
diaphragm forms the base of a paper cone which is then placed
over the dish, which is moderately heated on a sand-bath for
several hours. At the
end of that time, the
whole is allowed to
cool, and the benzoic
acid is found in light,
brilliant, crystalline

FIG. 131.
flakes on the sides of
the cone, and on the
diaphragm.
The benzoin resin
may also be powdered
and digested with milk
of lime for twenty-
four hours; it is then
heated to ebullition
and filtered. Hydro-
chloric acid precipi-
tates benzoic acid from the filtered liquid, which contains cal-
cium benzoate.
In Germany, large quantities of benzoic acid are prepared
by boiling the urine of horses and cows with hydrochloric acid.
The hippuric acid which these urines contain is thus decom-
posed into benzoic acid and glycocol. The benzoic acid crys-
tallizes on cooling, and is purified by sublimation.
Properties.-Benzoic acid crystallizes in needles, or in thin,
brilliant plates. It has an aromatic odor, and a slightly acid
It melts at 121°, and boils at 250°.
taste.
It dissolves in 607 parts of water at 0°, and in about 12
parts of boiling water. When boiled with a quantity of water
insufficient to dissolve it, it melts. It volatilizes with the vapor
of water. It dissolves readily in alcohol and in ether. When its
vapor is passed over red-hot pumice-stone, contained in a porce-
lain tube, it is decomposed into carbonic anhydride and benzol.
HIPPURIC ACID.
627
CH6O2 CO + CH
When heated with phosphorus pentachloride, it yields ben-
zoyl chloride.
CHO.OH + PC1
POC¹³ + HCl + C'H³O.Cl
Benzamide, CH5-CO.NH².--This body is formed by the
action of ammonia gas on benzoyl chloride.
C6H5CO.Cl + 2NH³
NH*C + CH_CO.NH
2
It is also formed by the action of ammonia on ethyl benzoate.
CH3–CO.OC?H + NH* = CH.OH + CH–CO.NH
Ethyl benzoate.
5
Alcohol.
Benzamide.
2
It occurs in brilliant, colorless, oblique rhombic crystals,
fusible at 128°, and can be sublimed without decomposition.
It is soluble in hot water and in alcohol.
Benzoic Acetone, Benzophenone, or Diphenyl-ketone,
C13 H10O C6H5-CO-CH³. This body is formed, together
with benzol, in the destructive distillation of calcium benzoate
(Chancel).
Ca(CH³-CO²)2
Calcium benzoate.
CaCO3 +
(C6H5)2CO
Diphenyl-ketone.
It forms large, colorless, or slightly yellow, right rhombic
prisms, fusible at 48-49°, and boils at 295°. It is insoluble
in water, but very soluble in alcohol.
Friedel and Crafts obtained it by treating benzol with chloro-
carbonic gas in presence of aluminium chloride.
2C'H® + COCI² =2HCl + (CH)CO
HIPPURIC ACID.
C9H9N03
CH2.NH(C7H50)
CO.OH
One of the most important of the benzoic derivatives is hip-
puric acid. Its relations with the benzoic series are manifested
by its decomposition by hydrochloric acid into benzoic acid and
glycocol.
C9H9NO³
Hippuric acid.
+ H2O
CHO²
C2H5NO2 +
Glycocol.
Benzoic acid.
Rouelle, Foureroy, and Vauquelin discovered this acid in
the urine of the horse, but confounded it with benzoic acid.
628
ELEMENTS OF MODERN CHEMISTRY.
Its true nature was recognized by Liebig in 1830. Dessaignes
has made its synthesis by the reaction of benzoyl chloride on
the zinc compound of glycocol.
C²H³NO² + C'H³O.Cl
Glycocol.
Benzoyl chloride.
C²H¹(C'H³O)NO² + HCl
Hippuric acid.
Hippuric acid is obtained from the urine of horses and cows
by mixing the urine with 2 or 3 times its volume of concen-
trated hydrochloric acid. The hippuric acid separates in col-
ored crystals.
When properly purified, it crystallizes in long, colorless
prisms, but slightly soluble in cold water, very soluble in boil-
ing water and in alcohol. When heated in a retort, it decom-
poses and yields a sublimate of benzoic acid. At the same
time a certain quantity of an oily body having a disagreeable
odor distils: it is phenyl cyanide, or benzonitrile, CN.C®H³.
SALICYL ALDEHYDE, OR SALICYL HYDRIDE.
CH*(OH).CHO
C7H6O2
This compound, which is isomeric with benzoic acid, exists
naturally in the essential oil of the meadow-sweet (Spiræa ul-
maria). Piria obtained it by oxidizing salicin by potassium
dichromate and sulphuric acid (page 588).
It is a colorless, highly refracting liquid, and boils at 196.5°.
Its density at 13.5° is 1.173. Its odor is pleasant and its
taste burning. It is quite soluble in water, and dissolves in
alcohol and ether in all proportions. It has an acid reaction.
It produces a violet color with ferric chloride. Oxidizing
agents convert it into salicylic acid.
C'HO² + 0 CHO³
By the action of fused potassium hydrate, it is likewise
transformed into salicylic acid, with disengagement of hydrogen.
2
C'HO² + KOH
Salicyl aldehyde.
KC'H³O³ + H²
Potassium salicylate.
In presence of sodium amalgam and water, it fixes H² and
is converted into saligenin (Reincke and Beilstein).
C'H6O2 + H2
Salicyl aldehyde.
C'H8O2
Saligenin.
SALICYLIC ACID.
629
The latter body is also formed, according to Piria, by the
decomposition of salicin by ferments and acids (page 588). It
crystallizes in tables having a pearly lustre, or in small, brilliant
needles.
SALICYLIC ACID.
CH6O3 C6H¹(OH).CO²H
Formation and Preparation.-This body was discovered
by Piria, who obtained it, in 1839, by fusing salicyl aldehyde
with potassium hydrate.
C'HO² + KOH KC7H50³ ò
Oil of meadow-sweet contains it naturally, together with
salicyl aldehyde. The essential oil of Gaultheria procumbens
(winter-green) is methyl salicylate (Cahours), that is, sali-
cylic acid, in which the atom of basic hydrogen is replaced by
methyl.
Salicylic acid is ordinarily prepared by boiling oil of winter-
green with caustic potassa as long as methyl alcohol is dis-
engaged. Potassium salicylate is formed, and is afterwards
decomposed by an excess of hydrochloric acid. The salicylic
acid separates, and is purified by recrystallization from boiling
water.
Kolbe and Lautemann formed salicylic acid by synthesis by
passing carbon dioxide into phenol in which sodium was dis-
solved. Sodium salicylate is thus formed.
CH*OH + CO.O
Phenol.
C6H⭑(OH)
со.он
Salicylic acid.
Kolbe has recently improved this process. Indeed, salicylic
acid is formed by simply passing dry carbon dioxide over
sodium phenate at a temperature of 180°. The temperature
is finally raised to 250°, and the product of the reaction, freed
from an excess of phenol by distillation, constitutes sodium-
salicylate of sodium.
2C6H5.ONa + CO²
Sodium phenate.
CH³.OH + CHONA
( CO²Na
Phenol.
Sodium-salicylate of sodium.
The mass is exhausted with water, and the solution is treated
with hydrochloric acid, which sets free the salicylic acid.
53*
630
ELEMENTS OF MODERN CHEMISTRY.
This process permits of the rapid and economical manu-
facture of large quantities of salicylic acid.
Properties. Salicylic acid crystallizes from its alcoholic
solution in large, quadrilateral prisms, and from its aqueous
solution in long needles. It melts at 156°. When mixed with
pumice-stone and rapidly distilled, it breaks up into carbon
dioxide and phenol.
C'H6O3 CO + CHO
It is very soluble in alcohol and ether, and in boiling water,
but cold water scarcely dissolves it. Its aqueous solution pro-
duces a deep violet color with the ferric salts.
When salicylic acid is treated with nitric acid, it is converted
into two isomeric nitrogenized acids; both are nitrosalicylic
acids, C'H (NO)O".
a-nitrosalicylic acid crystallizes in long, colorless needles,
which are anhydrous and melt at 228°; they are very slightly
soluble in cold water. It produces a blood-red color with ferric
chloride.
B-nitrosalicylic acid crystallizes in long, colorless needles,
containing one molecule of water of crystallization. When
heated, it loses this water and melts at 144-145°. It is slightly
soluble in cold water. Its solution also produces a blood-red
color with ferric chloride. This acid is also formed when
indigo is long boiled with nitric acid. It was formerly called
indigotic acid.
Salicylic acid possesses antiseptic properties like phenol,
without presenting the same inconveniences as the latter as
regards odor and causticity.
Methyl Salicylate, C'H³(CH³)O³.—Cahours first recognized
the oil of Gaultheria, known as essence of winter-green, to be
methyl salicylate. When purified, this body forms a colorless
oil, having a pleasant odor. It boils at 223.7°. Its density at
0° is 1.1969. Like the phenols, it has the characters of a
weak acid. When a concentrated solution of potassium hy-
drate is added to methyl salicylate, a precipitate of potassium
gaultherate is formed. Cahours discovered the existence of an
isomeride of methyl salicylate. It is methylsalicylic acid. The
following formulæ indicate the constitutions of these bodies :
C6H4.OK COH+.OCH³ C6H4.OCI13
со осна
C6H4.OH
CO.OF
Salicylic acid.
C6H4.OH
со осна
Methyl
salicylate.
Potassium
gaultherate
со.он
Methylsalicylic
acid.
CO
Methyl
methylsalicylate.
OXYBENZOIC AND PAROXYBENZOIC ACIDS.
631
OXYBENZOIC AND PAROXYBENZOIC ACIDS.
These two acids are isomeric with salicylic acid.
Oxybenzoic Acid is formed under various circumstances;
especially when metachloro-benzoic acid, a chloro-derivative
of benzoic acid, is heated with potassium hydrate.
C'H CIO²+2KOH = C'H°(OK)0² + KCl + H2O
It is an anhydrous, crystalline powder, consisting of small,
square tables. Sometimes it is in mammillated crystals. It melts
at 200°, and can be distilled without alteration. It is only
slightly soluble in cold water, but dissolves more readily in boil-
ing water.
Paroxybenzoic Acid is formed under rather remarkable cir-
cumstances. We have already seen that in presence of sodium,
phenol fixes carbon dioxide, forming sodium salicylate. If the so-
dium be replaced by potassium, the same reaction produces potas-
sium paroxybenzoate. The same salt is formed when potassium
phenate is heated to 210 or 220° in a current of carbon dioxide.
Paroxybenzoic acid crystallizes in transparent, oblique rhom-
bic prisms, containing one molecule of water of crystallization.
When anhydrous, it melts at 110°. It is much more soluble
in water and alcohol than salicylic acid. Its aqueous solution
does not produce a violet color with ferric chloride.
Anisic Compounds. When the oils of anise, of fennel, or
of tarragon are heated with nitric acid, they are converted into
a colorless oil, having a spicy odor, and boiling at 248°. This
is anisic aldehyde, CHO". By a more complete oxidation,
this aldehyde is converted in anisic acid, C8H8O³. Anisic alde-
hyde and acid present very simple relations of composition with
paroxybenzoic acid.
Anisic aldehyde is methylparoxybenzoic aldehyde, and anisic
acid is methylparoxybenzoic acid.
C6II4
он
CO.OH
C6H4.
OCH³
CO.OH
Paroxybenzoic acid.
Methylparoxybenzoic,
or anisic acid.
OCH3
CH*CHO
Methylparoxybenzoic,
or anisic aldehyde.
TYROSINE.
C9H11NO3
This body seems to be related to the preceding compounds.
It may be regarded as amidopropionic acid in which one atom
632
ELEMENTS OF MODERN CHEMISTRY.
of hydrogen is replaced by the group C'H.OH (paroxyphenyl)
as it exists in paroxybenzoic acid.
C2H5
CO2H
C2H+(NH2)
CO²H
C2H3(C6H4.OH) (NH2)
CO2H
Propionic acid. Amidopropionic acid.
Oxyphenyl-amidopropionic
acid (tyrosine).
Tyrosine is the product of the decomposition of many nitro-
genized matters in the animal economy. It may be prepared
by boiling for sixteen hours 1 part of horn shavings with 2
parts of sulphuric acid diluted with 4 times its volume of water.
The liquid is then neutralized with milk of lime, filtered, the
filtrate evaporated to half its volume, acidified with sulphuric
acid, and treated with an excess of lead carbonate.
The solution, which contains the tyrosine as lead salt, is de-
composed by hydrogen sulphide, filtered, and evaporated. The
tyrosine crystallizes out, and may be purified by several crystal-
lizations. The mother-liquors contain leucine.
Tyrosine crystallizes in long, colorless needles, often united
in tufts. It is but slightly soluble in water and in cold alcohol,
more soluble in hot alcohol, and insoluble in ether. It forms
definite compounds with both acids and bases. When fused
with potassium hydrate, it breaks up into paroxybenzoic and
acetic acids, and ammonia.
Tyrosine may be recognized by the following reaction.
When its aqueous solution is boiled with a solution of mer-
curic nitrate, as neutral as possible, a voluminous yellow precip-
itate is formed, which assumes a deep copper-red color by
boiling with nitric acid containing a small quantity of nitrous
acid.
GALLIC ACID.
C7H605 = C6H2(OH)3 ~ CO.OH
This acid is closely related to salicylic acid. It is dioxysali
cylic acid, and Lautemann obtained it by treating di-iodosali-
cylic acid with alkalies.
C'H¹I²0³ + 2KOH
Di-iodosalicylic acid.
2KI + C'H‘(OH)²O³
Gallic acid.
We have already seen that gallic acid is a product of the
decomposition of tannic acid. It is prepared by exposing
coarsely-powdered and moistened nut-galls to the air, renewing
the water as it evaporates. At the end of two or three months
INDIGO.
633
a black liquid is separated from the mass by strong pressure,
and the solid residue is exhausted with boiling water. Gallic
acid crystallizes out on the cooling of the filtered liquid. It is
purified by several crystallizations in boiling water.
Gallic acid forms long, silky needles, which contain one
molecule of water of crystallization. It has no odor; its taste
is astringent and slightly acid. When heated to 100°, it loses
carbon dioxide and is converted into a body which sublimes
in brilliant white lamina. This is pyrogallol, or pyrogallic
acid, and is employed in photography.
C'HO
Gallic acid.
CO² + CH³ (OH)³
Pyrogallol.
Gallic acid dissolves in 100 parts of cold water, and in 3
parts of boiling water. It is very soluble in alcohol, less soluble
in ether. Its solution gradually absorbs oxygen when exposed
to the air, and at the same time becomes colored and disengages
carbon dioxide.
If a recently boiled solution of gallic acid be passed up into
a tube filled with mercury and containing no air, and some
recently boiled baryta-water be then added, a white precipitate
is formed which at once changes to blue, if a few bubbles of
oxygen be introduced. The change of color is the indication
of an oxidation of the gallic acid, favored in this case by the
presence of the alkali.
INDIGO.
C8H5NO
Indigo is obtained from different species of the genus Indi-
gofera. The pastel, or woad (Isutis tinctoria), also furnishes a
coloring matter identical with indigo.
In India, indigo is prepared by macerating the stems and
leaves of the indigofera, collected at the time of flowering, with
water, in vats where they are allowed to ferment. In 12 or
15 hours the liquid is drawn off into other vats, where it is
agitated so as to bring it in contact with the air, an opera-
tion which occasions the formation of a blue precipitate. The
brown liquor is then drawn off, and the deposit is boiled in
copper vessels; it is then pressed between cloths and cut into
cubical pieces and dried. In this form the indigo is delivered
to commerce.
Indigo is not contained ready formed in the plants which
2B*
634
ELEMENTS OF MODERN CHEMISTRY.
serve for its manufacture. Schunck has shown that these plants
contain a substance analogous to the glucosides, indican, which
is decomposed by fermentation into indigo and indoglucin.
C26H³¹NO¹7 + 2H2O
Indican.
CH³NO + 3CH¹ºOº
Indigo.
Indican has been found in human urine.
Indoglucin.
The indigo of commerce contains from 50 to 90 per cent. of
coloring matter. It generally occurs in irregular masses, some-
times cubical, of which the shade varies from violet-blue to
blackish-blue. The most esteemed varieties present a brilliant
coppery reflection.
Pure indigo is called indigotine. It may be obtained by
heating the indigo of commerce in a current of hydrogen, or
by subliming it in small quantities between two watch-glasses
(Chevreul). It then forms right rhombic prisms having four
or six faces. Indigotine is insoluble in water, in cold alcohol,
and in ether. Boiling alcohol and oil of turpentine dissolve it
to a slight extent.
Concentrated, or better, fuming sulphuric acid dissolves in-
digo at 50 or 60°, forming a beautiful blue solution, which
contains two acids, sulphindigotic acid, CH'NO.SO³H, and
sulphopurpuric acid, C¹H³N³Ó³.SO³H. The solution of indigo
in sulphuric acid is used in dyeing; it is prepared by dissolving
indigo in a hot mixture of fuming and ordinary sulphuric acids.
The blue solution thus obtained is known as sulphate of indigo,
Saxon blue, or composition blue.
Boiling dilute nitric acid converts indigo into isatin. The
concentrated acid converts it first into nitrosalicylic acid, C'H³
(NO)O³, and then into picric acid.
When heated with potassium hydrate, indigo is converted
into anthranilic acid, CH(NH2O2, or into salicylic acid,
which is formed at the expense of the anthranilic acid.
C'H' (NH2)² + KOH
Anthranilic acid.
KCHO3 + NH3
Potassium salicylate.
When indigo is distilled with potassium hydrate, aniline
passes over, being formed at the expense of the anthranilic acid
first formed.
C'H'NO²
Anthranilic acid.
CO + CHỒN
Aniline.
White Indigo, C16H12N2O2.-This body, which was discov-
ered by Chevreul in 1812, results from the action of nascent
ISATIN.
635
hydrogen on indigo. It is produced when the latter substance
is submitted to the action of alkaline solutions in presence of
reducing matters, such as sulphurous or phosphorous acid,
hydrogen sulphide, iron, zinc, or ferrous or stannous hydrate.
2CH'NO + H² C¹¹6H¹²N2O2
White indigo is ordinarily prepared by introducing a mix-
ture of indigo, ferrous sulphate, slaked lime, and water into a
vessel, which should be entirely filled with the mixture and
then hermetically sealed and allowed to stand for two days. A
clear, alkaline solution is thus obtained, which is decanted, and
supersaturated with hydrochloric acid, out of contact with the
air. A deposit of white indigo is formed, and must be collected
on a filter, rapidly washed with boiled water, and dried in a
vacuum..
The body thus obtained has a dirty-white color, and is with-
out either taste or smell. It is insoluble in water, but dissolves
with a yellow color in alcohol, ether, and alkaline solutions.
On contact with air it absorbs oxygen, and is converted into
blue indigo. Nitric acid rapidly brings about this transformation.
Uses. Indigo is largely used in dyeing. The principle of
its application depends on the conversion of the blue indigo into
white indigo by reducing agents. The reduced white indigo
is soluble in alkaline solutions and in this form is fixed on the
fabrics, after which it is reconverted into blue indigo by ex-
posure to the air. The mixture just indicated for the prepara-
tion of white indigo (ferrous sulphate, indigo, lime, and water)
is most frequently employed. It constitutes what is known as
the vitriol vat.
Schützenberger and de Lalande have recently described a
process of dyeing with indigo, based on the employment of
sodium hydrosulphite.
ISATIN.
C8H5NO2
This body was discovered by Erdmann and Laurent in 1841.
It is a product of the oxidation of indigo by dilute nitric acid.
CH NO + 0 C8H NO²
Pure isatin crystallizes sometimes in large, dark, gold-
colored prisms, sometimes in small, reddish-yellow prisms
having a brilliant lustre. It is only slightly soluble in cold
water and in ether, but more soluble in boiling water, and very
636
ELEMENTS OF MODERN CHEMISTRY.
soluble in alcohol.
aniline.
When distilled with potassa, it yields.
CH³NO² + 4KOH 2K2CO3 + CH'N + H2
Isatin.
Aniline.
By the action of chlorine, isatin yields substitution pro-
ducts. These latter break up, like isatin itself, by the action
of potassium hydrate, yielding chloranilines (Hofmann).
C8H+CINO² + 4KOH
Monochlorisatin.
2K²CO³ + C6H6CIN + H2
Monochloraniline.
Products of the Reduction of Isatin.-To isatin are re-
lated certain products of its reduction, which are interesting
and which have been studied by Knop and Baeyer. They are
Dioxindol
Oxindol
Indol
C8H7N02
C8H7NO
C8117N
The first two are formed successively by the action of sodium
amalgam on an aqueous solution of isatin.
CH5NO² + H²
Isatin.
C8H7NO2
Dioxindol.
CH'NO² + H²
CH'NO + H2O
Dioxindol.
Oxindol.
By reducing oxindol by zine powder with the aid of heat,
Baeyer obtained indol.
CH'NO + Zn
Oxindol.
CH'N + ZnO
Indol.
Indol is a crystallizable solid, fusible at 52°. It volatilizes
with the vapor of water. Its odor recalls that of naphty-
lamine. It dissolves readily in boiling water, and in alcohol
and ether. It has basic properties.
Baeyer has recently obtained isatin and indigo by synthesis.
By heating phenyl-acetic acid with nitric acid, and reducing
the nitro-compound so formed, oxindol is obtained.
CH2
co
C6H4
CH*<NH>C0
This is converted into nitroso-oxindol, CH+.
NH
CH(NO)—co, and
CH(NH2)
co.
By oxidizing the
CO
NH
co. When isa-
this by reduction yields C6H4NH
latter compound, isatin is obtained, C6H
tin is heated with phosphorus pentachloride, hydrochloric acid
is disengaged, and a chloro-compound is formed, CH⭑<
and this by reduction yields indigo, CH< >CH
CH.
CO
N
CO
N
CCI,
PHTHALIC ACID.
637
XYLOLS AND DERIVATIVES.
C8H10 = C6H¹(CH3)2
That portion of coal-tar which boils between 136 and 139°
contains a mixture of isomeric hydrocarbons, which is desig-
CH³
nated as xylol or xylene. It is dimethylbenzol, CH*
CH<CIT
CH³
and can exist in three different isomeric modifications, like all
of the di-substituted derivatives of benzol.
Metaxylol, which boils at 137°, predominates in the mixture.
of xylols which is obtained from coal-tar. When oxidized by
chomic acid, it is converted into isophthalic acid, CH¹( CO*H)².
Orthoxylol is a colorless liquid, boiling at 140-141°. Nitric
acid oxidizes it to orthotoluic acid.
Paraxylol is solid, and crystallizes in oblique rhombie prisms,
fusible at 15°. It boils at 136-137°. Dilute nitric acid con-
verts it into paratoluic acid. Chromic acid oxidizes it to ter-
aphthalic acid.
There are very many derivatives allied to these isomeric
xylols. One or more atoms of hydrogen may be replaced,
either in the benzol nucleus or in the methyl chains, by chlo-
rine, bromine, or by groups such as OH, NO, NH, etc. The
methyl chains may be oxidized by boiling the xylols with nitric
or chromic acid, as indicated above. In this case the group
CH³ is replaced by the carboxyl group CO.OH, and the hy-
drocarbons, C'H¹(CH³)², are converted into either toluic acids
or phthalic acids, of each of which there are three isomerides.
CIB
C6II+
CH13
Xylols.
CH³
C6II+
CO.OH
Toluic acids.
CO.OH
C6II+
CO.OH
Phthalic acids.
We cannot describe all of these bodies here, but must limit
ourselves to a brief description of phthalic acid and its isomer-
ides.
PHTHALIC ACID.
C8H6O+ C'H (CO.OH)²
Ordinary, or Orthophthalic Acid.-Laurent obtained this
acid by boiling naphthalene for a long time with nitric acid. It
crystallizes in brilliant scales, or in short, thick prisms, which
are but slightly soluble in cold water, very soluble in hot water,
alcohol, and ether. It melts at 213°, and loses the elements
of water at a higher temperature, being converted into phthalie
anhydride.
54
638
ELEMENTS OF MODERN CHEMISTRY.
C6 H+
CO.OH
CO.OH
Phthalic acid.
CO
H2O + C6H4.
CO
Phthalic anhydride.
Phthalic anhydride crystallizes in long, brilliant prisms, fusi-
ble at 127-128°. It boils at 277°. It possesses a remarkable
property, which was discovered by A. Baeyer, and which is now
applied practically in the arts. When heated with the phenols,
it combines with them directly with elimination of the elements
of water, and compounds are obtained which are designated as
phthaleins.
Thus, when phthalic anhydride is heated with ordinary
phenol, two molecules of phenol combine with one molecule
of phthalic anhydride, with elimination of one molecule of
water, and the phthalein of phenol is obtained.
C6H5.0II
C6H4
CO
CO
0 +
C6 [15.OH
Phthalic anhydride.
2 mol. phenol.
CO-COI14.OH
CO-CII.OH
C6H4
Phthalein of phenol.
+ H2O
When resorcin is heated with phthalic anhydride, two mol-
ecules of water are eliminated, and a body is obtained to which
Baeyer has given the name fluorescein.
C6H+<
CO
+
C6114(OH)2
C6II¹(OH)2
Phthalic anhydride.
CO-C6H3.0II
C6II+
0 + 21120
CO-CH³.OH
Fluorescein.
2 mol. resorcin.
Fluorescein forms orange-red, crystalline grains, insoluble in
cold water, and but slightly soluble in boiling water. It dis-
solves readily in solutions of the alkalies and alkaline carbonates.
Its dilute solutions are yellow, and have a magnificent green
fluorescence. Hence the name fluorescein.
Tetrabromo-fluorescein, CH® Br¹O³, is employed in dyeing
under the name eosin. It communicates to silk a beautiful
rose-red tint.
Teraphthalic Acid (paraphthalic).-Cailliot obtained this
body by submitting oil of turpentine to a long ebullition with
dilute nitric acid. The same acid is formed by the oxidation
of paraxylol and its derivatives by potassium dichromate and
sulphuric acid. It is a white powder, almost insoluble in water,
alcohol, and ether. It sublimes without melting and without
decomposition.
Isophthalic Acid (metaphthalic) is formed by the oxidation
of metaxylol. Long, thin, colorless crystals, slightly soluble in
water, soluble in alcohol, and fusible above 300°. ` It may be
sublimed without decomposition.
NAPHTHALENE.
639*
NAPHTHALENE.
C10H8
This important compound was discovered by Garden in 1820,
in coal-tar. Its composition was determined by Faraday, and
its properties and transformations were principally studied by
Laurent,
It is a frequent product of the dry distillation of organic
matters, and is formed in abundance when these matters, or
the products of their decomposition, are heated to high tem-
peratures. Thus it is formed in large quantities when tar is
passed through red-hot tubes.
Naphthalene is extracted from coal-tar, and is purified by
crystallization in alcohol, or by sublimation.
Properties.-Naphthalene occurs in rhombic tables when it
has been sublimed, and is deposited in prisms from its ethereal
solution. It melts at 79.2°, and boils at 218°. It is inflam-
mable, and burns with a very smoky flame. It is insoluble in
water, slightly soluble in cold alcohol, freely soluble in boiling
alcohol, and very soluble in ether.
Nitric acid attacks naphthalene, forming nitro-derivatives,
among which is nitro-naphthalene, CH(NO2), which crystal-
lizes in sulphur-yellow, rhombic prisms, fusible at 43°. By
long boiling with nitric acid, naphthalene is converted into
phthalic acid, nitrophthalic acid, and oxalic acid.
Chlorine acts on naphthalene in two ways: it combines di-
rectly, forming chlorides of naphthalene, and produces numerous
substitution products which generally combine with an excess
of chlorine.
Bromine yields only substitution compounds with naphtha-
lene.
Among all these products, we may mention the following:
C10H8C12 naphthalene dichloride. C10117C monochloronaphthalene.
C10118C14 naphthalene tetrachloride. C¹º116C12 dichloronaphthalene.
C10HC12C14 dichloronaphthalene tetra- C10H5C13 trichloronaphthalene.
chloride.
C10CISCI2 perchloronaphthalene di- C10C18 perchloronaphthalene.
chloride.
Concentrated sulphuric acid dissolves naphthalene, forming
two acids:
Naphtylsulphurous acid,
Naphtyldisulphurous acid, C¹016
C10 H7.SO³II
J SO³H
\ SOPII
640
ELEMENTS OF MODERN CHEMISTRY.
The formation of the first of these acids is expressed in the
following equation :
C10H8+ SO¹H²
2
Naphthalene.
H2O + C¹ºH7.SO³H
Naphtylsulphurous acid.
NAPHTOL.
C10H7. ОН
This body is formed artificially by treating naphthalene with
sulphuric acid, and fusing the naphtylsulphurous acid so ob-
tained with potassium hydrate (see page 606).
C¹º H.SO³K + KOH K²SO³ + C¹¹ºH'.OH
Potassium naphtylsulphite.
Naphtol.
It forms silky needles or laminæ, soluble in alcohol, ether,
and benzol, almost insoluble in cold water, slightly soluble in
boiling water. It melts at 94°. Its aqueous solution produces
a violet color with chloride of lime.
An isomeride of naphtol is known, ẞ-naphtol, fusible at 122°.
NAPHTYLAMINE.
C10H9N
C10 H7.NH2
Zinin obtained this base in 1842 by reducing nitronaphtha-
lene by ammonium sulphydrate, which may be advantageously
replaced by iron and acetic acid.
CH'(NO) + 3H²
Nitronaphthalene.
2H2O + C¹ºH7(NH2)
Naphtylamine.
It forms fine, colorless needles. It sublimes at a gentle heat,
melts at 50°, and boils without alteration at 300°. It has a
fetid odor. Its reaction is not alkaline, although it perfectly
neutralizes the acids, with which it forms well-defined and
crystallizable salts. When exposed to the air, the salts of
naphtylamine acquire a violet color, probably due to an absorp-
tion of oxygen.
ANTHRACENE AND PHENANTHRENE.
C14H10
Anthracene, which is solid, exists in the less volatile pro-
ducts of the distillation of coal-tar. It is obtained from the
last products of this operation. The mass, which has a buttery
consistence, is squeezed in a filter-press, and the residue is sub-
ALIZARIN.
641
mitted to repeated distillations; it is finally purified by com-
pression and several crystallizations in benzol.
Anthracene may be formed artificially by several processes,
especially by passing the vapor of toluol and various derivatives
of that body through a tube heated to bright redness. Under
these conditions, two molecules of toluol lose six atoms of hy-
drogen, and are converted into anthracene.
C6H5-CH3
C6H5-CH3
2 mol. toluol.
3H2
C6H4-CH
C6H4 CH
Anthracene.
In the pure state, anthracene forms rhombic tables, derived
from an oblique rhombic prism. The crystals are colorless,
and present a magnificent blue fluorescence (Fritzsche). They
melt at 213°, and distil without alteration at about 360°.
By the action of oxidizing agents, such as chromic acid, an-
thracene is converted into a solid body, which crystallizes in
beautiful yellow needles, fusible at 273°, and which can be
sublimed without alteration. It is anthraquinone, CH³O², a
body which bears the same relations to anthracene as quinone
to benzol.
C6H6
Benzol.
CH⭑O2
Quinone.
C14H10
Anthracene.
C¹4H8O2
Anthraquinone.
By treating anthraquinone with bromine, Graebe and Lieber-
mann converted it into dibromanthraquinone, CHºBr³Ó³, a
solid body, which crystallizes in yellow needles.
Phenanthrene. Besides anthracene, there is another hydro-
carbon of the same composition, which exists in coal-tar, and
may also be formed artificially. It is called phenanthrene, and
forms colorless scales, having a bluish fluorescence. It melts
at 100°, and boils at 340°. It is soluble in 50 parts of alco-
hol at 13°; very soluble in hot alcohol, and in ether and
benzol.
ALIZARIN.
C14H804
C¹4H6(OH)202
Natural State and Synthesis.-Alizarin is the name applied
to the coloring matter of madder which Robiquet was the first
to extract in a pure state. Graebe and Liebermann have re-
cently made its synthesis by heating dibromanthraquinone to
200° with potassium hydrate.
54*
642
ELEMENTS OF MODERN CHEMISTRY.
C4H6Br2O+ 2KOH= 2KBr + CH(OH)202
Dibromanthraquinone.
Alizarin.
This reaction, slightly modified, has become within a few
years the base of an important industry.
Alizarin does not exist ready formed in the madder plant.
The latter contains a glucoside to which Robiquet has given
the name ruberythric acid, and which is decomposed by the
action of acids into alizarin and glucose.
C26H28014+ 2H2O
Ruberythric acid.
C¹¹H8O + 2C6H12O6
Alizarin.
Glucose.
Preparation. Alizarin may be extracted from madder by
boiling the latter with a solution of alum. The filtered liquid,
left to itself for some days, deposits impure alizarin as a brown-
red precipitate, and holds in solution another coloring matter
which is called purpurin.
The precipitated alizarin is purified by washing with dilute
hydrochloric acid, and crystallization in alcohol. The product
thus obtained is exhausted with a boiling solution of alum,
which removes the purpurin, and is finally dissolved in ether,
which deposits it in crystals.
To prepare artificial alizarin from anthracene, that hydro-
carbon is first transformed into anthraquinone, and the latter
body is treated with sulphuric acid to convert it into disulpho-
anthraquinonic acid, which is then heated with an excess of
potassium hydrate.
C¹¹H6 (SO³K)2O2 + 2KOH
Potassium
disulphoanthraquinonate.
6
C¹¹¹H°(OH)²O² + 2K²SO³
Alizarin.
The alkaline mass is dissolved in water, precipitated by hy-
drochloric acid, and the precipitate purified by crystallization
in alcohol and finally by sublimation.
The artificial product is delivered to commerce in the form
of a paste, but the reaction by which it is formed produces, at
the same time, isomerides which remain mixed with the aliza-
rin, properly so called. Eight isomeric compounds are known
having the composition CHO. One of them, purpuroxan-
thin, is contained in small quantity in madder.
Properties of Alizarin-Alizarin forms long, brilliant,
orange-yellow prisms. It is scarcely soluble in cold water, but
dissolves somewhat better in boiling water, and is soluble in
alcohol, ether, and carbon-disulphide. Between 215 and 225°,
it sublimes in long, orange-yellow needles. It dissolves in sul-
PURPURIN-NATURAL ALKALOIDS.
6-43
phuric acid with a blood-red color, and water precipitates it
without alteration from this solution. Boiling dilute nitric
acid converts it into oxalic and phthalic acids. When alizarin
is heated to redness with zinc powder, it is reduced to anthra-
cene (Graebe and Liebermann).
Alizarin forms combinations with the bases; it dissolves in
ammonia, with a purple color, and in the caustic alkalies, yield-
ing purple solutions which have a blue reflection.
Uses.-Alizarin produces a red color on fabrics that are mor-
danted with alumina, and a violet on those which are mor-
danted with ferric oxide. It is the coloring principle of madder
and of the commercial product known as garancin. The latter
product is obtained by heating powdered madder with sulphu-
ric acid to 100°, and exhausting the mass with water. The
residue is garancin.
PURPURIN.
C14H5(OH)302
This name is given to another coloring matter which may
be
extracted from madder, and which has already been mentioned.
It appears to exist in the plant as a glucoside. It dissolves
readily in alcohol and ether, with a red color.
It crystallizes from weak alcohol in orange-colored needles,
which contain one molecule of water of crystallization. From
concentrated alcohol, it deposits in red, anhydrous needles.
When heated, it melts and sublimes in red needles.
Purpurin is an oxyalizarin, or a trioxyanthraquinone, C¹H5
(OH)³O²: indeed, it may be obtained by treating a solution of
alizarin in concentrated sulphuric acid with an oxidizing agent,
such as manganese dioxide (de Lalande). Inversely, the reduc-
tion of purpurin reproduces alizarin (Rosenstiehl). It under-
goes a complete reduction, and is converted into anthracene,
when heated with zinc-dust.
Independently of the purpurin just described, there are three
other compounds isomeric with it.
NATURAL ALKALOIDS.
The alkaloids are nitrogenized substances capable of uniting
with the acids, like ammonia, and forming with them definite
combinations which constitute true salts. A large number
644
ELEMENTS OF MODERN CHEMISTRY.
of these compounds can be formed artificially, and are derived
directly from ammonia by the substitution of organic radicals
for the hydrogen of that body. They are the compound, or
substituted ammonias, and their constitutions are perfectly
known. This is not, however, the case with the natural alka-
loids, which have been discovered in many plants and vege-
table products, and which often constitute the active principles
to which these products owe their medicinal virtues. By anal-
ogy, it may be inferred that these bodies also are derived from
ammonia, like the compound ammonias.
In 1806, the basic nature of one of the crystallizable princi-
ples of opium was discovered by Sertürner, but his discovery
was unnoticed until 1817, when he published it in a treatise
on morphine. Among the more important discoveries in this
class of compounds must be mentioned those of strychine,
brucine, and especially quinine, discoveries which are due to
Pelletier and Caventou (1820).
All of the alkaloids contain nitrogen. They are divided into
two classes, the first of which includes the liquid and volatile
bases, and the second the solids. The latter generally contain
oxygen, the former do not. The alkaloids possess one charac-
teristic property which indicates their analogy with ammonia.
With platinic chloride their hydrochlorides form double salts,
which are sometimes insoluble in water, sometimes soluble and
crystallizable.
If a solution of platinic chloride be poured into a solution
of quinine hydrochloride, a yellow precipitate is at once formed;
it is a combination of platinic chloride and quinine hydrochlo-
ride, and is sometimes called quinine chloroplatinate, or platino-
chloride.
CONINE.
C8H15N
This is a liquid and volatile alkaloid which is extracted from
the hemlock (Conium maculatum). The seeds of this tree are
crushed and distilled with sodium hydrate. The alkaline liquid
which collects in the receiver is neutralized by dilute sulphu-
ric acid, evaporated to a syrupy consistence, and the residue
exhausted with a mixture of alcohol and ether, which dissolves
the conine sulphate, and leaves ammonium sulphate. The alco-
hol and ether are driven out by evaporation; a concentrated
NICOTINE.
645
solution of sodium hydrate is added to the conine sulphate, and
the liquid is distilled. The conine passes with a certain quan-
tity of water, on which it floats. It is separated, dried over
some fragments of calcium chloride, and rectified in a vacuum.
Conine is a limpid, oleaginous liquid, having a penetrating
and nauseating odor, recalling that of hemlock. It boils at
168°. It is slightly soluble in water, more so in cold than
in hot water, so that a cold, saturated solution becomes clouded
when heated. It is very soluble in alcohol and in ether. It
has a strongly alkaline reaction, immediately restoring the blue
color to reddened litmus-paper. It precipitates many metallic
oxides from solutions of their salts. On contact with the air
it becomes brown and resinified.
Conine is often mixed with methylconine, a compound de-
rived from conine by the substitution of a methyl group for
an atom of hydrogen (Planta and Kekulé).
Wertheim has obtained from the flowers and seeds of the
hemlock a solid alkaloid, which he has named conhydrine,
CH¹NO, and which contains the elements of conine plus a
molecule of water.
Hugo Schiff has recently made the synthesis of an isomeride.
of conine, which he calls paraconine.
NICOTINE.
C10N 1402
This alkaloid exists in tobacco. It may be obtained by ex-
hausting tobacco with boiling water and evaporating the liquid
to a syrupy consistence on a water-bath; the still hot extract
is then mixed with twice its volume of alcohol, allowed to settle,
and the alcoholic liquid separated from the thick lower layer,
which contains much calcium malate. The alcohol is distilled
off, and the residue exhausted with strong alcohol, of which
the greater part is then driven off by evaporation. Potassium
hydrate is added to the alcoholic extract, which is then agitated
with ether, which dissolves the nicotine set free. A few grammes
of oxalic acid added to the ethereal solution causes the separa-
tion of a syrupy deposit which contains oxalate of nicotine.
This salt is decomposed by potassa, and the nicotine set free is
dissolved out by ether. After the ether has been expelled on
a water-bath, the nicotine is distilled in a current of hydrogen,
that part being retained which passes above 180° (Schlocsing).
646
ELEMENTS OF MODERN CHEMISTRY.
Properties. Nicotine is a colorless liquid, having an offen-
sive, penetrating odor. It rotates the plane of polarization to
the left. It boils between 240 and 250°, not, however, with-
out undergoing partial decomposition. Above 146°, it begins
to distil slowly, and at 100° it emits white vapors; at ordinary
temperatures it gives off so much vapor that a rod wet with
hydrochloric acid will be enveloped in white fumes if held a
little distance above the nicotine.
Nicotine dissolves in all proportions in water, alcohol, and
ether. It has a strongly alkaline reaction, and perfectly neu-
tralizes the acids, and precipitates the metallic oxides from
solutions of their salts. It is one of the most violent poisons
known.
ALKALOIDS OF OPIUM.
Opium is the thickened juice of the capsules of the white
poppy (Papaver somniferum). It is obtained by making in-
cisions in these capsules from the base to the summit. A milky
juice exudes, and in the course of a day thickens and solidifies
in tears. These are removed, pressed together, and fashioned
into variously-formed masses.
Opium contains a number of alkaloids combined with several
acids. Among the latter are a syrupy acid, to which Ander-
son gave the name thebolactic acid, but which has recently
been recognized to be identical with lactic acid (Buchanan),
and meconic acid, of which the composition is expressed by
the formula C'H'O'. The latter is one of the more important
constituents of opium; it possesses the characteristic property
of producing a blood-red color with ferric salts. Opium con-
tains also a gummy matter, soluble in water, and a brown, in-
soluble, resinous matter, which remains in the mass when
opium is exhausted with water. The aqueous solution of opium
has a brown color. The following alkaloids have been obtained
from opium:
Morphine C7H19 NO3
Codeine
C18 H21 NO3
Thebaine
C19 H21 NO3
Papaverine C21 H21 NO4
Narcotine C22H23N07
Narceine C23 H29 NO9
Besides these, Merck has described another alkaloid of opium
under the name porphyroxine; but, according to Hesse, this
MORPHINE.
647
body is a mixture of several bases, to which he has given the
names meconidine, laudanine, codamine, and lanthopine.
Opium sometimes contains an alkaloid which is designated
as pseudomorphine, and which is oxymorphine, CHNO¹.
Independently of these alkaloids, a neutral, crystallizable
substance has been extracted from opium, and called meconine,
C10H100. Of all these bodies, we will only consider morphine,
codeine, and narcotine.
MORPHINE.
C17H19NO3 + H2O
Preparation.-1. Opium is cut into slices and exhausted
with water. The solution is evaporated to a syrupy consistence
and the still hot extract is mixed with an excess of pulverized
sodium carbonate. After the lapse of twenty-four hours, the
precipitate is collected and exhausted with dilute acetic acid,
which dissolves the morphine and leaves the narcotine. The
liquid is filtered, decolorized by animal charcoal, and super-
saturated with ammonia. The morphine is precipitated, and
is purified by crystallization in alcohol (Merck).
2. One kilogramme of opium is exhausted with cold water;
100 grammes of pure lime are added to the liquid, which is
then evaporated to a syrupy consistence at a temperature of 65
or 75°. After cooling, the mass is exhausted with 3 litres of
water which leaves the meconate of calcium; the latter is
separated by filtration. The liquid is then evaporated to one-
fourth its volume, and while it is still hot, 50 grammes of
calcium chloride dissolved in 100 grammes of water and 8
grammes of hydrochloric acid are added.
This mixture is left to itself for about two weeks, when it
will be found to have set in a mass of crystals which are bathed
in a colored mother-liquor. The deposit is pressed in a cloth,
dissolved in boiling water, with addition of animal charcoal,
and the solution filtered. On cooling, a mass of crystals is
formed, consisting of a mixture of morphine hydrochloride and
codeine hydrochloride. These are pressed, dissolved in water,
and ammonia is added, which precipitates the greater portion of
the morphine, while the codeine remains in solution. The
deposit is collected on a filter and redissolved in boiling alcohol,
from which the morphine crystallizes on cooling (Robertson
and Gregory).
648
ELEMENTS OF MODERN CHEMISTRY.
Properties.-Morphine crystallizes in small, colorless, right
rhombic prisms, having a bitter taste. It is insoluble in ether,
in chloroform, and in benzol. The alcoholic solution rotates
the plane of polarization to the left. The crystals contain one
molecule of water which they lose at 100°. Morphine dis-
solves easily in a solution of potassium hydrate; it is very
slightly soluble in ammonia; almost insoluble in water.
Tests.-1. If a few drops of a solution of iodic acid be added
to an alcoholic solution of morphine, the liquid immediately
assumes a brown or yellow color, due to the liberation of iodine.
Iodic acid exerts an oxidizing action on morphine.
2. If a small quantity of morphine in powder be added to a
solution of ferric chloride, a blue color is produced.
3. Nitric acid produces an orange-red color with morphine.
The last two reactions are characteristic.
When morphine is heated to 200° with potassium hydrate,
it disengages methylamine.
Morphine Hydrochloride.-This salt, of which the prepara-
tion has already been indicated, crystallizes in silky needles,
soluble in 1 part of boiling and 16 or 20 parts of cold water;
it is very soluble in alcohol. The crystals contain C¹7H¹ºNO³.
HCl + 3H²0.
Platinic chloride forms a yellow precipitate of a double chlo-
ride in an aqueous solution of morphine hydrochloride.
(C¹HNO³.HCl)2.PtCl
Hydrochloride of morphine is much used in medicine.
When its solution is heated to 60° with silver nitrite, the
base is oxidized and converted into oxymorphine, CH¹NO.
When morphine is heated to about 140° with concentrated
hydrochloric acid, it is transformed into a new base, apomor-
phine, CH"NO", derived from morphine by the removal of
one molecule of water (Matthiessen). This base possesses
special therapeutic properties. When administered by hypo-
dermic injection or swallowed, it acts as an emetic.
CODEINE.
C18H21 NO3 + H2O
Codeine is methylmorphine. It is obtained from the am-
moniacal mother-liquor from which the morphine is deposited,
in the preparation of the latter body by the process of Robert-
NARCOTINE.
649
son and Gregory. For this purpose, the mother-liquor is con-
centrated and caustic potassa is added, which precipitates the
codeine. It is collected, dissolved in hydrochloric acid, the
solution decolorized with animal charcoal, and the codeine again
precipitated by potassa. Lastly, the precipitate is dissolved in
ordinary ether, which deposits the codeine in voluminous crys-
tals by spontaneous evaporation.
These crystals are right rhombic prisms, and contain one
molecule of water. Anhydrous ether deposits codeine in anhy-
drous rectangular octahedra.
Codeine dissolves in 89 parts of water at 15°, and is more
soluble in boiling water. Alcohol and ether dissolve it readily,
and the alcoholic solution rotates the plane of polarization to
the left.
If bromine-water be poured upon codeine in fine powder,
the latter dissolves, and is converted into hydrobromide of
monobromo-codeine. By the continued addition of bromine-
water, a yellow precipitate is formed, consisting of hydrobro-
mide of tribromo-codeine, that is, codeine in which three atoms
of hydrogen are replaced by three atoms of bromine.
NARCOTINE.
C22H 23 NO
Narcotine may be extracted from the residue of opium which
has been exhausted by water. This is treated with hydrochloric
acid, filtered, and the filtrate precipitated by sodium carbon-
ate. The precipitate is dissolved in alcohol, and the alcoholic
solution decolorized by animal charcoal. The narcotine crys-
tallizes out on cooling.
It forms brilliant, colorless prisms, belonging to the system
of the right rhombic prism. It melts at 70°. It is insoluble in
cold water, and requires for its solution about 60 parts of cold
absolute alcohol, or 12 parts of boiling absolute alcohol. It is
soluble in ether, a character which distinguishes it from mor-
phine. Its alcoholic and ethereal solutions have a bitter taste,
and turn the plane of polarization to the left.
If a few crystals of narcotine in a watch-glass be moistened
with sulphuric acid containing a trace of nitric acid, an intense
blood-red color is produced.
By the action of certain oxidizing agents, narcotine is de-
2c
55
650
ELEMENTS OF MODERN CHEMISTRY.
composed into a new alkaloid, cotarnine, and an acid which is
called opianic acid (Wöhler).
23
C²²H²³NO
Narcotine.
+ 0
C¹ºH¹º05 + C¹²H¹³NO
Opianic acid.
Cotarnine.
Cotarnine crystallizes in colorless, silky needles, grouped in
stars.
When subjected to the action of hydriodic acid, narcotine
loses successively three methyl groups, and yields hydriodides
of three new bases. One of them contains C¹⁹H¹NO', and has
been designated as nornarcotine or normal narcotine. It is
formed according to the equation
C²²H³NO + 3HI
Narcotine.
C¹⁹H¹NO + 3CH³I
Nornarcotine.
Methyl iodide.
Hence narcotine itself represents trimethyl-nornarcotine,
C19H¹(CH3)3NO' (Matthiessen and Foster).
The intermediate terms between narcotine and nornarcotine
are also known,
ALKALOIDS OF CINCHONA.
The different cinchona barks owe their febrifuge virtues to
several alkaloids, of which the more important, quinine and cin-
chonine, were discovered by Pelletier and Caventou in 1820.
Since then, quinidine and cinchonidine have been isolated, the
first isomeric with quinine, the second with cinchonine. All
of these are crystallizable alkaloids. When their sulphates are
heated with sulphuric acid, they are converted into two new
isomerides, quinicine and cinchonicine. The latter are not crys-
tallizable.
Hence the following six alkaloids are known :
Cinchonine, cinchonidine, cinchonicine
Quinine, quinidine, quinicine.
C201124N20
C20 H24N202
These alkaloids are by no means distributed in the same
manner in the numerous species and varieties of cinchona bark,
and these barks are not equally rich in alkaloids. The follow-
ing summary gives some indications of this difference :
1 KILOGRAMME OF BARK YIELDS :
Yellow bark (Cinchona Calisaya)
Red bark (Cinchona succirubra)
Loxa (Cinchona condami-
nea)
Huanuco (Cinchona nitida)
Pale bark
CINCHONINE
SULPHATE.
QUININE SULPHATE.
30-32 grammes.
20-25
6-8 grammes.
8
C
8
6
6
12
QUININE.
651
In the cinchonas, these alkaloids are combined with a well-
defined, crystallizable acid, whose composition is expressed by
the formula C'H12O6. It is quinic acid.
This acid is obtained from the calcium quinate which is de-
posited in a few days, when the liquid separated from the quino-
calcium precipitate is concentrated and allowed to stand (see
farther on).
This calcium quinate is purified by several crystallizations,
and its solution decomposed by oxalic acid. The quinic acid
remains in the solution, and separates in crystals when the
liquid is properly concentrated.
Quinic acid crystallizes in beautiful, transparent, oblique
rhombic prisms. It is very soluble in water, and but slightly
soluble in absolute alcohol. It melts at 161.5°, losing at the
same time the elements of water.
Its aqueous solution rotates the plane of polarization to the
left.
Its composition corresponds to the formula CH12O6. When
distilled with a mixture of sulphuric acid and manganese diox-
ide, it yields quinone, CH¹O³.
A substance is also found in cinchona bark which is called
quinotannic acid. It belongs to the tannin group, and is a
glucoside. Hlasiwetz states that it can be decomposed into
glucose and cinchonine red, a substance noticed by Pelletier and
Caventou as produced during the preparation of quinine.
QUININE.
C20 H24N202
When ammonia is added to a solution of sulphate of quinine,
a white precipitate of quinine is obtained, which, when left to
itself and moistened with water from time to time, becomes
crystalline by combining with one molecule of water.
Quinine is very bitter. It dissolves in 2266 parts of cold,
and in 760 parts of boiling water; in 1.33 parts of cold alco-
hol, and 22.6 parts of ether (J. Regnauld). It is also soluble
in chloroform. Its alcoholic solution turns the plane of polar-
ization to the left. When water at 32° is added to the hot
alcoholic solution until a cloud begins to form, resinous quinine
is deposited, and also colorless, prismatic crystals containing
three molecules of water.
Quinine Sulphate, 2(C¹²ºH²N²O²).SO¹II² + SII³O.—Prep-
652
ELEMENTS OF MODERN CHEMISTRY.
ration. This salt, which is extensively used in medicine, is
prepared by boiling yellow bark (Cinchona Culisaya) or red
bark (Cinchona succirubra) with water acidulated with sul-
phuric or hydrochloric acid. A slight excess of milk of lime
is then added in small quantities to the decoction, and precip-
itates not only the quinine and cinchonine, but all of the color-
ing matter (cinchonine red), which forms an insoluble com-
pound with the lime. The quinic acid remains in solution as
calcium quinate. The quino-calcium deposit contains also the
excess of lime, and calcium sulphate, in case sulphuric acid
has been employed. It is collected on a cloth, allowed to drain,
pressed, and dried. It is then exhausted with boiling alcohol,
which dissolves out the alkaloids.
The alcoholic solution, concentrated by distillation, deposits
the cinchonine in crystals, in case the bark employed be rich
in that alkaloid. The mother-liquor retains the quinine. It
is neutralized by sulphuric acid, and the alcohol distilled off.
The quinine sulphate crystallizes in a mass on cooling, and is
purified by redissolving it in boiling water and adding animal
charcoal.
It has been proposed to replace the alcohol, in the extrac-
tion of the quino-calcium deposit, by certain fixed or volatile
oils, which dissolve quinine. For this purpose, petroleum and
the heavy oils produced by the distillation of tar, and which are
abundant in commerce, may be used with advantage. After
having dissolved the alkaloids in these oils, the solutions are
agitated with dilute sulphuric acid, which removes from them
the quinine and cinchonine. Sulphates are thus obtained which
may be crystallized.
Properties. Quinine sulphate occurs in long, thin, light
needles, which are somewhat flexible. It requires for its solu-
tion 740 parts of water at 13°, or about 30 parts of boiling
water. The solution restores the blue color to reddened litmus-
paper. It turns the plane of polarization to the left (Bouchar-
dat). When crystallized in alcohol, quinine sulphate contains
only two molecules of water.
If some quinine sulphate be suspended in cold water, and a
few drops of sulphuric acid be added, the sulphate dissolves.
and the liquid acquires a blue fluorescence.
21
In this case, quinine sulphate, which is a basic salt, is con-
verted into a salt, C2H2 N2O2.SO'H', which has an acid reac-
tion, and is called quinine acid sulphate. This salt crystallizes
CINCHONINE.
653
with 7 molecules of water. A still more acid sulphate is known,
C²ºH²¹N²O². (SÒ¹H²)² + 7H²O.
If an excess of chlorine-water be added to a solution of
quinine sulphate, and the liquid be supersaturated with ammo-
nia, a beautiful green color will be produced.
This reaction is characteristic of quinine.
When tincture of iodine is added to a solution of quinine
sulphate in hot acetic acid, in a few hours the liquid deposits.
large, thin plates. It is iodoquinine sulphate, C20H¹N²O²I².
SO H²+5HO (Herapath).
2
24
These crystals appear green by reflected light, and are almost
colorless by transmitted light. When two of them are crossed,
the portions which are superposed almost entirely intercept the
passage of light. In this respect, iodoquinine sulphate acts
as a polarizer, like tourmaline.
Uses. Quinine sulphate is a valuable remedy. It is prin-
cipally employed as a febrifuge, and generally in the treatment.
of diseases of an intermittent type. It is successfully admin-
istered in other diseases, especially in acute articular rheuma-
tism, gout, certain neuralgias, etc.
CINCHONINE.
C20H24N2O
Cinchonine is obtained as an accessory product in the manu-
facture of quinine. It deposits from its alcoholic solution in
brilliant, colorless, quadrilateral prisms. It is insoluble in
water, but soluble in alcohol and chloroform. It is almost
insoluble in ether, a property which distinguishes it from qui-
nine. Its alcoholic solution turns the plane of polarization to
the right.
Cinchonine has a bitter taste. It melts at 170°, and when
cautiously heated in the bottom of a closed tube, it partly sub-
limes in very light, delicate crystals. When treated with a
dilute solution of potassium permanganate, it forms various
substitution products, and a new base remains, less oxidizable
than cinchonine. It is hydrocinchonine. Caventou and Willm
consider that this base is contained, in the state of mixture, in
commercial cinchonine.
By oxidizing cinchonine with nitric acid, Weidel has ob-
tained a series of acids, one of which contains nine atoms of
carbon; it is quinolic acid, CºH®N²O*, while two others contain
55*
654
ELEMENTS OF MODERN CHEMISTRY.
14
each eleven atoms. Lastly, the fourth of these acids, cinchonic
acid, has the composition (H4NO. When distilled, it yields
a non-nitrogenized acid, C¹ºH¹O³, pyrocinchonic acid, which is
an isomeride of opianic acid.
10
STRYCHNINE AND BRUCINE.
Pelletier and Caventou discovered these two alkaloids in
various vegetable products derived from plants belonging to the
genus Strychnos, such as nux vomica (seeds of the Strychnos
Nux vomica), false angustura bark, which comes from the same
Strychnos, Saint Ignatius bean (seeds of the Strychnos Ignatiï),
etc. These alkaloids, to which igasurine has recently been
added (Desnoix), appear to be combined in the Strychnos with
an acid but little known, which Pelletier and Caventou called
igasuric acid.
Strychnine, C2H22N2O2.-Preparation.-Strychnine is ex-
tracted from nux vomica by a process analogous to that which
serves for the preparation of quinine. The crude strychnine
which deposits in crystals from its alcoholic solution is always
mixed with brucine. The two alkaloids are separated by con-
verting them into nitrates, which are made to crystallize; the
strychnine nitrate, less soluble than that of brucine, deposits.
in needles, and the concentrated solution afterwards deposits
voluminous crystals of brucine nitrate. To isolate the alka-
loids, the corresponding nitrates are precipitated by ammonia,
and the alkaloid dissolved in boiling alcohol, which deposits it
in crystals on cooling.
Properties. Strychnine crystallizes in rectangular octa-
hedra, sometimes in quadrilateral prisms terminated by four-
sided pyramids. It is colorless and odorless, but extremely
bitter. It is insoluble in water and in ether, and scarcely
soluble in absolute alcohol. It dissolves readily in ordinary
alcohol, in chloroform, and in the volatile oils. Its alcoholic
solution turns the plane of polarization to the left.
Strychnine is one of the most active poisons known; even
in very small doses it produces violent tetanic spasms.
Brucine, C2H26N²O + 4H²O.-Brucine, separated from
strychnine by the process above indicated, crystallizes by slow
evaporation of its solution in weak alcohol in oblique rhombic
prisms, which are often quite large. These crystals, which
contain four molecules of water, rapidly effloresce in the air.
COCAINE-ACONITINE.
655
Brucine is almost insoluble in water, but dissolves readily in
alcohol and very slightly in ether. The alcoholic solution ro-
tates the plane of polarization to the left.
If brucine be moistened with nitric acid, it immediately
assumes a blood-red color and, by the aid of a gentle heat,
disengages carbon dioxide and vapors which contain methyl
nitrite (Strecker).
COCAINE.
C17H21 NO4
Cocaine was obtained by Niemann from coca leaves (Ery-
throxylon Coca). It has been studied by Wöhler and Lassen.
Preparation.-Coca leaves are exhausted several times with
water at a temperature between 60 and 80°, and the solu-
tion is precipitated by lead acetate, and filtered; the filtered.
solution is freed from excess of lead acetate by addition of
sodium sulphate and then, after a new filtration, the solution
is evaporated. Sodium carbonate is then added until it pro-
duces a faint alkaline reaction; the liquid is lastly agitated
with ether, which takes up the cocaine and leaves it on evapo-
ration.
Properties. Cocaine crystallizes in oblique rhombic prisms
of four or six sides, which are colorless and odorless, and fuse
at 98°. It is but slightly soluble in cold water, more soluble in
alcohol, very soluble in ether. Its taste is bitter, its reaction
slightly alkaline. When heated with hydrochloric acid, it ab-
sorbs two molecules of water and decomposes into methyl alco-
hol, benzoic acid, and a crystallizable base, ecgonine, CH¹³NO³
+ H2O.
21
C¹H²¹NO + 2H²O
C⁹H¹³NO³ + CH¹O + C'HĜO²
ACONITINE.
C27 H 40N010
It
The Aconitum Napellus contains, independently of aconitic
acid, a base which was extracted by Geiger and Hesse.
occurs as a white powder, or as colorless, tabular crystals, only
slightly soluble in water, very soluble in alcohol. Its taste is
acrid and bitter. It is a violent poison. Its nitrate crystal-
tizes readily.
656
ELEMENTS OF MODERN CHEMISTRY.
ATROPINE.
C17H 23 NO3
This alkaloid, which is largely used in the treatment of dis-
eases of the eyes, was discovered in 1833 by Geiger and Hesse,
and by Mein, in the belladonna, or deadly nightshade (Atropa
Belladonna). Planta has shown the identity of atropine and
daturine, which has been obtained from the thorn-apple
(Datura Stramonium).
Preparation.-Belladonna-root is reduced to powder and
digested several days with alcohol. The solution is filtered,
slaked lime, in quantity equal to one-twentieth of the weight of
root employed, is added, the solution again filtered, and rendered
slightly acid with sulphuric acid. It is again filtered, and 3 of
the alcohol distilled off. The residue is concentrated at a gentle
heat, and a concentrated solution of potassium carbonate is added
until the liquid, now neutral, begins to be clouded. After a few
hours, the precipitate is separated by filtration, and potassium
carbonate is added to the filtrate as long as impure atropine is
precipitated. The next day, the deposit is collected on a filter,
pressed, dried, and exhausted with 96 per cent. alcohol. The
solution is decolorized with animal charcoal, the liquid diluted
with five or six times its volume of water and put in a cool,
dark place. The atropine is deposited in 12 or 24 hours in
crystalline needles.
Properties. Atropine crystallizes in delicate needles, fusi-
ble at 90°. It dissolves in 300 parts of cold water, and in
almost all proportions of alcohol. It is less soluble in ether.
At 140° it volatilizes, but the greater part of it is decomposed.
In burning, atropine diffuses the odor of benzoic acid. When
it is treated with potassium dichromate and sulphuric acid,
benzyl aldehyde distils and benzoic acid is formed (Pfeiffer).
Atropine is a virulent poison. A solution of sulphate of
atropine is used in medicine. A single drop, even of a very
dilute solution of this salt, produces dilatation of the pupil.
THEOBROMINE.
C7H8N402
Theobromine exists in the beans of the cacao (Theobroma
Cacao). To prepare it, the crushed cacao beans are exhausted
CAFFEINE-ALBUMINOID MATTERS.
657
with water, and the aqueous extract is precipitated by lead ace-
tate. The precipitate is separated by filtration, and the filtrate.
is freed from an excess of lead by hydrogen sulphide; it is then
again filtered, and evaporated to dryness. The residue is dis-
solved in absolute alcohol and the solution concentrated; the
theobromine separates as a crystalline powder, having a bitter
taste, slightly soluble in alcohol and ether. It may be sublimed.
It is soluble in ammonia.
CAFFEINE, OR THEINE.
C8H10N+O2 + H2O
Caffeine was extracted from coffee in 1821 by Pelletier and
Caventou, and by Robiquet and Runge. Liebig, Pfaff, and
Wöhler determined its composition. It exists in coffee, tea,
Paraguay tea (leaf of the Ilex Paraguaiensis), and guarana
(seeds of the Paullinia Sorbilis). The latter product contains
5 per cent. Caffeine is methyl-theobromine.
•
Preparation.-Caffeine, or theine, is generally obtained
from tea. Powdered tea is exhausted several times with cold
alcohol, and the tincture is precipitated by subacetate of lead,
filtered, and a current of hydrogen sulphide passed through
the filtrate to precipitate the excess of lead. The filtered liquid
is then evaporated to one-fourth its volume, neutralized by po-
tassium hydrate, and allowed to crystallize (Herzog).
}
Properties.-Caffeine forms long, silky needles, which are
light and colorless. It loses its water of crystallization at 100°,
melts at 178°, and sublimes without alteration at a higher tem-
perature. It is only slightly soluble in cold water, but dissolves
readily in boiling water, and in alcohol. It is but slightly soluble
in ether. It forms definite combinations with the acids. When
boiled with concentrated potassa, it disengages methylamine.
When caffeine is boiled for a few minutes with fuming nitric
acid, the yellow liquid evaporated to dryness, and the residue
moistened with ammonia, a purple color is produced, analogous
to that of murexide.
ALBUMINOID MATTERS.
The albuminoid matters are complex organic substances, con-
taining carbon, hydrogen, oxygen, and nitrogen, which are often
associated with a small proportion of sulphur. By their com-
20*
658
ELEMENTS OF MODERN CHEMISTRY.
position and properties they are allied to the coagulable matter
which exists in white of egg and in the serum of blood, and
which is called albumen.
The epidermic productions and the insoluble substances
which are converted into gelatin or chondrin by boiling, differ
from albumen and its allied compounds by their composition.
They contain less carbon and more nitrogen. For this reason
the neutral nitrogenized matters of the economy are divided
into two comprehensive classes, albuminoid substances proper,
and those substances which resemble in composition the insol-
uble matter which forms the cartilage of bones, and which
yield gelatin by the action of boiling water.
The more important of the albuminoid bodies are as follows:
Albumen
Fibrin
Casein
•
Globulin
Syntonin
·
•
Myosin
Vitellin
Hemoglobin
•
A nitrogenized matter, coagulable by heat, and exist-
ing in many liquids of the animal economy, particu-
larly in white of egg and the serum of blood.
A nitrogenized matter, which deposits in the solid state
during the coagulation of blood.
A nitrogenized matter, existing in milk, and considered
identical with albuminate of sodium.
An albuminoid substance that can be obtained from
the red blood-corpuscles.
An albuminoid substance, resulting from the action of
very dilute hydrochloric acid on muscular fibres.
An albuminoid body contained in muscular fibres.
The albuminoid matter of yolk of egg.
A crystallizable substance contained in red blood-cor-
puscles.
Among the cartilaginous and gelatinous substances are the
following:
Ossein, or collagene, which forms the cartilage of bones, and yields gelatin
when boiled with water.
Chondrogin, which constitutes the cartilage of the short ribs, and which
yields chondrin when boiled with water.
Keratin, or horny structure.
Elastin, the constituent of elastic tissue.
Fibroin, a product peculiar to silk-worms, etc.
The substances belonging to these two groups possess the
following elementary composition :
·
Carbon
Hydrogen
Nitrogen
Oxygen.
Sulphur
•
FIRST Group.
53.5
6.9
SECOND group.
50.0
6.6
15.6
16.8
26.1 to 23.1
1 to 1.6
0.5 to 3.5
23 to 22.4
100.0
100.0
ALBUMINOID MATTERS.
659
Of most of the albuminoid substances, two modifications
are known, one soluble and the other insoluble. Thus heat,
acids, and alcohol convert soluble albumen into insoluble albu-
men, and the latter appears to have the same, or very nearly
the same composition after coagulation as before.
The insoluble albuminoid bodies, such as coagulated albu-
men, cooked albumen, fibrin, and casein, dissolve by the aid of
a gentle heat in potassium hydrate, to which they yield a
portion of their sulphur. The alkaline liquid, supersatu-
rated with acetic acid, precipitates the dissolved matter in
flakes.
Concentrated and boiling solutions of the alkalies decompose
all albuminoid substances, the principal products of the decom-
position being carbon dioxide, formic acid, glycocol, and its
homologue leucine, CHNO, as well, as a nitrogenized sub-
stance known as tyrosine and containing CH"NO³. The other
decomposition products will be indicated when treating of
albumen.
Leucine and tyrosine are also formed when albuminoid sub-
stances are long boiled with dilute sulphuric acid. At the same
time, aspartic acid, and glutamic acid, C'H'NO', which is the
acid amide of normal pyrotartaric acid, is formed.
C3H6.
CO2H
CO2H
Pyrotartaric acid.
CO'H
CH(NH)<COH
Glutamic acid.
Concentrated hydrochloric acid dissolves the insoluble albumi-
noid bodies, and the solution assumes a violet color, especially
on contact with the air (Caventou).
When brought into contact with water containing one or
two thousandths of hydrochloric acid, insoluble albuminoid mat-
ters swell up and are finally converted into a transparent jelly,
which partially dissolves in water.
By the action of energetic oxidizing agents, such as chromic
acid, or manganese dioxide and sulphuric acid, albuminoid
bodies produce various products of oxidation and decomposi-
tion, among which we may note particularly: (1), the volatile
acids of the series, CnH2O2, from formic acid to caproic acid
inclusive; (2), the corresponding aldehydes; (3), the nitriles
(hydrocyanic ethers), propionitrile (ethyl cyanide), and valero-
nitrile (butyl cyanide); (4), benzoic acid and benzyl alde-
hyde.
660
ELEMENTS OF MODERN CHEMISTRY.
ALBUMEN.
Two modifications of albumen are known: one is soluble,
the other insoluble.
Soluble albumen exists in solution in white of egg, and in
other liquids of the animal economy. The coagulable prin-
ciple of the serum of blood is a liquid very analogous to the
albumen of white of egg; some chemists have called it serin.
When a filtered solution of white of egg is evaporated at a
low temperature or in a vacuum, the soluble albumen at length
dries to a transparent, yellowish mass, having a gummy appear-
ance. In this state it is not pure; it remains combined with
a trace of alkali and mixed with a small quantity of salts.
When treated with water, it again dissolves.
When it is per-
fectly dry, it may be heated to even 100° without losing all of
its water. The greater part, if not all, of the salts which exist
in white of egg with the albumen may be removed by dialysis
(Graham).
When a solution of white of egg or of the serum of blood
is heated, the liquid begins to be clouded at 70°, and coagulates
at about 73°, sometimes in flakes, sometimes in a white mass,
according to the concentration of the solution; heat converts
albumen into the insoluble variety.
When white of egg is diluted with eight or nine times its
volume of water and the carbonic acid gas which is dissolved
or combined with the albumen is carefully expelled at a low
temperature, a solution is obtained which is not coagulable by
heat. The lost property may, however, be restored by passing
carbon dioxide through the liquid.
It is generally considered that there is no difference of com-
position between soluble and insoluble albumen. However,
Schützenberger finds that the difference is sensible. If strong
alcohol be added to a solution of albumen, a white coagulum is
formed, which becomes insoluble in water by the prolonged
action of alcohol.
Action of Acids on Albumen.-Sulphuric, hydrochloric, and
nitric acids precipitate albumen in thick flakes, which retain a
certain quantity of acid; the latter may be removed by pro-
longed washings with water.
The action of nitric acid upon albumen is often used for the
detection of that substance in pathological urine. A still more
ALBUMEN.
661
sensitive reagent is metaposphoric acid, which precipitates the
smallest traces of albumen contained in a solution.
Ordinary phosphoric acid, acetic acid, and lactic acid, do not
precipitate solutions of albumen.
Action of Alkalies on Albumen.-When white of egg is
beaten up with a few drops of a very concentrated solution of
potassium hydrate, it sets in a few minutes in a soft, trans-
parent, semi-solid mass, from which the excess of potassa may
be removed by washing with cold water. The residue is albu-
minate of potassa, from which all of the excess of potassa may
be removed by prolonged washings. This gelatinous albumi-
nate of potassa dissolves in boiling water. Acetic acid precip-
itates the albumen from the solution.
When potassa is added to a solution of albumen, albuminate
of potassa is formed in the same manner; acetic acid precip-
itates the albumen, which it renders insoluble, but the alkaline
solution is not troubled by boiling. If a few drops of lead
acetate be added to the liquid, the oxide of lead formed will
remain dissolved in the excess of alkali. The liquid then
blackens on boiling, for the sulphur contained in the albumen
acts on the lead, forming lead sulphide.
Insoluble albumen dissolves in the alkalies and alkaline car-
bonates, forming albuminates.
Albumen combines with calcium hydrate, as with potassa;
a mixture of white of egg and slaked lime constitutes a very
hard cement.
By subjecting albumen and its analogues to the action of
an aqueous solution of barium hydrate at a temperature of 140
or 150°, Schützenberger observed that these bodies decompose,
by hydration, into ammonia, carbon dioxide, oxalic, sulphurous,
and acetic acids (the latter three bodies in very small propor-
tion), and into other products, which are mostly crystalliza-
ble. These products are tyrosine and the acid amides of the
fatty series CH2n+1NO", from amidobutyric acid, CH' (NH²)O²,
to amid-œnanthic acid, C'H (NH²)O², inclusive. With these
products are others which are also crystallizable, but contain
less hydrogen; lastly, more highly oxidized amides are formed
in the same reaction, such as malamic, diamidocitric, aspartic,
and glutamic acids.
13
From these results, it may be inferred that albumen and its
analogues contain the elements of urca, tyrosine, acid amides
of the fatty series, and more oxidized amides analogous to as-
56
662
ELEMENTS OF MODERN CHEMISTRY.
partic acid, all of these bodies being combined together, with
elimination of water. The presence of a certain proportion of
a dextriniform body in the products of the decomposition of
albumen permits the supposition that the complex molecule of
the latter body contains also an amide of cellulose or an amy-
laceous body.
Action of the Salts on Albumen.-Many salts precipitate
solutions of albumen. Acetate and subacetate of lead form
dense precipitates of albuminate of lead. Cupric sulphate pro-
duces a blue precipitate. Corrosive sublimate yields a white
precipitate, even in very dilute solutions of albumen. The in-
solubility of this precipitate explains the use of albumen as an
antidote to corrosive sublimate.
Solutions of albumen are not precipitated by solutions of
sodium chloride or sodium sulphate, but when acetic acid is
added to the nrixture, a precipitate forms. Reciprocally, a solu-
tion of albumen to which acetic acid has been added is pre-
cipitated by solutions of sodium chloride and sodium sulphate
(Panum).
When incinerated, both soluble and insoluble albumen leave
a residue of calcium phosphate from which it is almost impos-
sible to free the albumen.
FIBRIN.
When recently-drawn blood is left to itself, it coagulates.
spontaneously in a few minutes, and soon separates into a yel-
low liquid called the serum, and a red coagulum, which is the
clot. The clot contains the red corpuscles, imprisoned in an
insoluble albuminoid matter. This matter is fibrin, and it is
now considered to be formed during the coagulation at the ex-
pense of two soluble substances, both of which exist in solution
in the liquid portion of blood, which is called plasma. One of
these substances is called fibrinogen, the other is the fibrino-
plastic matter or paraglobulin. These two bodies have been
isolated: when they are mixed in presence of water and a
certain proportion of sodium chloride, the whole dissolves at
first and the liquid soon coagulates spontaneously; the coagu-
lum is fibrin (Hoppe-Seyler).
However this may be, fibrin may be obtained in fibrous
masses by beating fresh blood. The latter does not coagulate.
in this case, but the coagulable constituent attaches itself in
MYOSIN.
663
red flakes to the rods with which the blood is agitated. By
washing these flakes in running water, they are freed from the
adhering red corpuscles, and obtained in white or grayish clas-
tic masses of a fibrous appearance. This substance is entirely
insoluble in pure water, but dissolves in slightly alkaline solu-
tions, and even, by the aid of a gentle heat, in solutions of
certain salts which have an alkaline reaction. It decomposes
hydrogen dioxide into oxygen and water.
When left to itself during the heat of summer, it putrefies
very rapidly, and is converted into a blackish liquid, which
contains albumen. Leucine, and butyric and valeric acids are
formed at the same time.
When treated with concentrated hydrochloric acid, fibrin
dissolves, forming a blue solution. When still moist fibrin is
introduced into water containing one or two thousandths of
concentrated hydrochloric acid, it swells and becomes trans-
parent, forming a jelly. After some time it dissolves in the
liquid, although with difficulty, and the solution then contains
a substance which appears to be identical with syntonin (see
farther on).
When fibrin, swollen by hydrochloric acid, is digested at
about 40° with gastric juice, or with the ferment called pepsin,
which may be obtained from that liquid, the fibrin entirely dis-
solves and is converted into a soluble and dialyzable body called
peptone. This body is formed during the digestion of albu-
minoid matters.
Under certain circumstances sodium chloride dissolves fibrin.
When such a solution is dialyzed, the salt passes into the cxte-
rior liquid, and there remains in the dialyzer a limpid solution
having all the characters of a solution of albumen from egg
(A. Gautier).
MYOSIN.
Kühne has designated by this name the albuminoid matter
which exists in solution in the sheaths of the muscular fibres
(sarcolemma), and which has the property of coagulating spon-
taneously after death, thus producing cadaveric rigidity.
Myosin is insoluble in water as well as in a saturated solu-
tion of common salt, but it dissolves in a solution containing
ten per cent. of salt. It may be extracted from the muscles
by the following process: the flesh is chopped up, and decolor-
ized by washing with water; it is then triturated with pul-
664
ELEMENTS OF MODERN CHEMISTRY.
verized common salt, and enough water is added to produce a
10 per cent. solution of salt. After digestion for a few hours
in the cold, the liquid is filtered and brought into contact with
rock salt; as the latter dissolves, it precipitates the myosin in
flakes.
Recently-precipitated myosin dissolves in a ten per cent.
solution of salt, but it loses this property by desiccation. Very
dilute hydrochloric acid dissolves it, and soon transforms it
into syntonin.
SYNTONIN.
This substance may be extracted from muscular tissue. The
latter is hashed, washed with water, and suspended in a large
quantity of water containing one-thousandth of hydrochloric
acid. The particles of meat swell and dissolve abundantly in
the liquid, which is then pressed through a cloth, filtered, ana
exactly neutralized with sodium carbonate. The syntonin is
precipitated in gelatinous, colorless flakes, which collect and
dry upon the filter in elastic films.
Syntonin dissolves in water slightly acidulated with hydro-
chloric acid. It also dissolves in lime-water, and in a one per
cent. solution of sodium carbonate.
HEMOGLOBIN.
be
This name is given to the crystalline matter which may
extracted from red blood-corpuscles, and which was first called
hematocrystalline.
Preparation.-Clotted blood is broken up and triturated
with its own volume of water until it is entirely reduced. It
is then passed through a cloth, and the liquid is frozen, or
agitated with small quantities of ether until the corpuscles are
dissolved. The thawed liquid, or that which has been treated
with ether, deposits a coagulum which imprisons all of the
unbroken corpuscles. The liquid is filtered, rendered slightly
acid by acetic acid, and alcohol is added as long as the pre-
cipitate first formed continues to dissolve. When cooled to 0°
for several hours, the red liquid sets in a mass of crystals;
these are collected on a filter, pressed, and washed with dilute
alcohol and water, both at 0°. They are purified by dissolving
them in water at 40° and evaporating the solution in a vacuum,
or by adding alcohol and cooling the liquid to 0°.
HEMOGLOBIN.
665
Composition. Hemoglobin so prepared has about the same
composition as albuminoid bodies, but contains a little iron.
According to Hoppe-Seyler, its composition is
Carbon.
Hydrogen.
Nitrogen
Oxygen
Iron
•
•
54.18
7.2
16.2
21.5
0.42
0.7
Sulphur
Properties. Hemoglobin forms crystals which differ accord-
ing to the blood from which they have been obtained. They
generally belong to the type

of the right rhombic prism.
Those from human blood pre-
sent, under the microscope, the
forms indicated in Fig. 132.
They are red, and doubly re-
fracting. They contain water
of crystallization.
They dissolve in water, and
more readily in slightly alkaline
solutions.
The red solution of hemo-
globin (oxyhemoglobin) hast
an important optical property.
When light which has trav-
ersed a dilute solution of hemo-
globin is decomposed by a
FIG. 132.
prisin, the spectrum so formed shows two black bands (absorp-
tion bands) between Fraunhofer's lines D and E (Stokes).
The crystals of hemoglobin contain oxygen which is weakly
combined, and which may be removed by exposing the crys-
tals in a vacuum (Hoppe-Seyler). Oxygenated hemoglobin is
known as oxyhemoglobin, and hemoglobin deprived of oxygen
reabsorbs that gas when brought into contact with it. It is
curious that carbon monoxide will expel the oxygen from hemo-
globin, at the same time replacing it (Cl. Bernard). The com-
bination of hemoglobin and carbon monoxide is soluble in
water.
The solution of oxyhemoglobin yields its oxygen to certain
reducing agents, such as hydrogen sulphide. Reduced hemo-
globin gives an absorption spectrum containing one single band,
56*
666
ELEMENTS OF MODERN CHEMISTRY.
situated in a position between the two absorption-bands of oxy-
hemoglobin.
Hemoglobin decomposes hydrogen dioxide. It is very un-
stable, and if the crystals be dried at a temperature above 100°
they rapidly become altered. The aqueous solution decom-
poses spontaneously in a few hours at 15°, or temperatures
above that point. The acids, even the weak ones, favor this
decomposition, which is manifested by a change of color, the
fine red tint of the hemoglobin being replaced by a brown. In
these cases, hemoglobin decomposes into an albuminoid matter
(globulin), and a ferruginous pigment called hematin. At the
same time, small quantities of fatty acids are set free (Hoppe-
Seyler).
Hematin. This substance has received different names.
Lecanu, who first studied it, named it hematosin. When prop-
erly purified, it forms a blackish-blue, amorphous powder, which
is quite stable, since it resists a temperature of 180°. It con-
tains carbon, hydrogen, nitrogen, oxygen, and iron.
incinerated, it leaves 12.8 per cent. of oxide of iron.
When
It is insoluble in water, alcohol, ether, and chloroform. It
dissolves in the alkalies, in ammonia, and in the acids, and is
readily soluble in ammoniacal alcohol and in alcohol containing
hydrochloric acid. These solutions are reddish-brown. With
hydrochloric acid, hematin forms a compound which crystallizes
in rhomboidal lamina; the crystals are characteristic and may
be recognized by means of the microscope (hydrochloride of
hematin).
Hematoidin. This body is doubtless a product of the
decomposition of hemoglobin. Virchow found it in orange-
colored crystals in the remains of old hemorrhages of the brain.
It is also found in blood which has been exposed to air, and in
extravasated blood in the Graefian follicles. It may easily be
obtained from the yellow bodies contained in the ovaries of the
cow, by triturating them with glass, and digesting for a few
days with chloroform. After evaporation of the yellow chloro-
form solution, the residue is treated with ether to dissolve out
the fat.
Hematoidin crystallizes in small, orange-red, transparent
prisms. It is insoluble in water and alcohol, slightly soluble
in ether; it is soluble in chloroform, which it colors golden-
yellow. It presents certain analogies with bilirubin (page
673).
GLOBULIN-CASEIN-GELATIN.
667
GLOBULIN.
Berzelius gave this name to the coagulable albuminoid sub-
stance which may be obtained from red blood-corpuscles, and
which is now believed to be a product of the decomposition of
hemoglobin. This, or an analogous substance, exists in the
crystalline lens. It may be obtained by boiling the crystalline
lens of the ox with water and filtering the liquid. A solution
of globulin is thus obtained. It much resembles albumen in
its properties. When heated, it becomes clouded at 73°, but
coagulates completely only at 93°. It is not precipitated by
either acetic acid or by the alkalies, but when its acid or
alkaline solution is neutralized, a precipitate is formed.
A
solution of globulin is precipitated by a current of carbon di-
oxide.
CASEIN.
When an acid is added to milk, a thick precipitate is at once
formed; it is produced by the casein. The lactic acid which
forms in milk by the fermentation of the milk-sugar, produces
the same precipitation. The milk is then said to curdle. The
precipitate consists of an albuminoid matter called casein,
which is considered to be identical with coagulated albumen.
Casein dissolves in alkaline liquids and even in certain alka-
line salts, such as carbonate and phosphate of sodium. It
exists in this state in milk, which is alkaline when fresh.
When this solution of alkaline albuminate, to which the name
soluble casein has been given, is evaporated, it becomes covered
with a pellicle. Acetic acid precipitates it in flakes, combining
with the alkali. It is also coagulated by the gastric juice,
which is acid, and which contains a ferment known as pepsin.
This ferment exists in rennet which is prepared from the
fourth stomach of the calf, and which serves to coagulate
skimmed milk in the preparation of cheese. Indeed, casein,
more or less altered by putrefaction, is the basis of the different
kinds of cheese.
GELATIN.
The bones contain a cartilaginous substance, which may be
isolated by dissolving out the mineral salts, which consist of
calcium carbonate and phosphate, with hydrochloric acid.
668
ELEMENTS OF MODERN CHEMISTRY.
There remains a semi-transparent, elastic substance, which re-
tains the form of the bone. This substance, which has been
called ossein, or collagene, is insoluble in cold water, but by
prolonged boiling, or more rapidly by digestion with water
heated to a few degrees above 100°, it dissolves and forms a
solution, which sets in a transparent jelly on cooling. The
body formed by this transformation dissolves slightly in cold
water, and abundantly in boiling water, and the hot solution
forms a jelly on cooling. Hence the name gelatin.
Other tissues of the animal economy may be converted into
gelatin by boiling with water. It is so with the cellular tissue,
the skin, the scales, and swimming-bladder of fishes. The
swimming-bladder of the sturgeon, known in commerce as fish-
glue, furnishes very pure gelatin by boiling with water.
The substances which may be converted into gelatin possess
very nearly the same composition as gelatin itself; hence no-
thing precise is known concerning the nature of the change
produced in them by the action of boiling water.
Dry gelatin occurs in transparent sheets, which are sonorous,
and of which the color varies from yellowish to brown, accord-
ing to their thickness and purity.
The aqueous solution is precipitated in white flakes by alco-
hol. The acids do not precipitate it, with the exception of
tannic acid, with which it forms a thick coagulum, a combina-
tion of tannin and gelatin. This action of tannin on gelatinous
matters is applied in the manufacture of leather, which is ob-
tained by leaving fresh or green skins, previously swelled by
soaking in water, in contact with tan, that is, coarsely-ground
oak-bark, which is well known to contain tannin.
When chlorine-water is added to a solution of gelatin, a
white cloud is formed which an excess of chlorine converts
into a white, flocculent precipitate.
Solutions of gelatin are precipitated by platinic chloride
and by corrosive sublimate, but not by alum or the salts of lead,
copper, silver, etc. When boiled with dilute sulphuric acid,
gelatin is converted into leucine and a substance to which
Braconnot gave the name sugar of gelatin, and which is gly-
cocol.
Chondrin.—When the cartilages of the short ribs are boiled
for a very long time with water, they dissolve, forming a liquid
which sets in a jelly on cooling. This gelatinous matter is
chondrin. It is distinguished from gelatin by the property of
RESPIRATION.
669
its aqueous solution to form precipitates with all the acids, and
with a great number of metallic salts. Alum formas in it an
abundant, flocculent precipitate.
matters.
The substances which have just been summarily described,
and others which form the liquids an dtissues of the animal
economy, undergo various transformations in the organism.
They are derived from the vegetable kingdom, which alone can
elaborate such complex matters. They pass with the aliments
into the animal organisms, which assimilate them, and this work
of assimilation does not profoundly modify the nitrogenized
But once fixed in the tissues, they do not remain
there indefinitely, for there is a continual change and renewal
of the whole economy. They become unfitted for the require-
ments of life, and disappear in their turn, eliminated by that
continual oxidation which makes of the body a permanent
hearth of slow combustion. A notable portion of the oxygen
which enters the lungs at each inhalation penetrates into the
blood, and is converted in the capillary system and the intrica-
cies of the tissues into carbon dioxide. This gas, which returns
to the lungs with the venous blood, is exhaled at each exhala-
tion. Expired air contains 4 to 5 per cent. of carbon dioxide.
The carbon dioxide eliminates the greater portion of the
carbon contained in the organic bodies burned during the phe-
nomenon of respiration. The hydrogen of these bodies is
eliminated in the form of water. But what becomes of their
nitrogen? In man, and a great number of the higher animals,
it is eliminated in the urea contained in the urine. Such are
the principal features of this grand function of respiration, the
source of heat in all animals.
But how is this slow oxidation which constitutes the object
of respiration, as first shown by Lavoisier, accomplished? Are
the organic matters ready to be oxidized and consumed at once,
or does the oxidation take place in successive phases, so that
there are a certain number of intermediate terms between the
complex products which must disappear and the final products
of their oxidation? All facts lead to the adoption of the latter
conclusion. Indeed, there are found in the tissues and liquids
of the economy a great number of bodies having compositions
more or less complex, and which are the products, and, as it
670
ELEMENTS OF MODERN CHEMISTRY.
·
were, the testimony of a successive simplification,—of disas-
similation, as it is called.
But it must not be supposed that all of the reactions which
take place in the economy are phenomena of oxidation. Be-
fore being definitely oxidized and rejected from the body, the
ingested organic matters and those which form our humors and
tissues, may undergo various transformations and sometimes
molecular complications. In this respect, Dr. Ure's celebrated
experiment is well known: having taken benzoic acid, he found
hippuric acid in his urine. Analysis has shown the presence.
in the animal economy of a multitude of more or less complex
organic compounds, nitrogenized and non-nitrogenized, having
definite compositions, and which are the products of varied
reactions. Such reactions take place in the blood and in the
tissues, principally in glandular organs, such as the liver. As
it would be impossible to consider all of these products of dis-
assimilation, we can only briefly notice the more important.
LECITHINE.
C42H84N PO9
Gobley has given this name to a phosphorized fatty matter,
before noticed in the brain by Vauquelin. It exists in the
brain and in the nerves. There is a closely allied body, recently
described by Liebreich, under the name protagon.
Gobley extracted lecithine from yolk of egg. That substance
is exhausted with a mixture of alcohol and ether, and an alco-
holic solution of cadmium chloride is added to the solution
obtained; a white, flocculent precipitate is formed, and is puri-
fied by washing with alcohol and ether. This precipitate is a
compound of cadmium chloride and hydrochloride of lecithine.
It is suspended in ether and decomposed by hydrogen sulphide:
cadmium sulphide is precipitated and hydrochloride of lecithine.
remains in solution, and may be obtained on evaporation in a
wax-like mass. When the alcoholic solution of this hydro-
chloride is decomposed by silver oxide, the lecithine is set free,
and remains, after evaporation, in the form of a homogeneous,
translucent mass. Lecithine may also be precipitated by pla-
tinic chloride instead of cadmium chloride (Strecker).
Lecithine and all of its compounds are very alterable. It
decomposes rapidly when the alcoholic solution of its hydro-
chloride is boiled with baryta-water; oleate and palmitate of
CHOLESTERIN.
671
barium are precipitated, phosphoglycerate of barium is formed,
and an organic base called neurine remains in solution (Lieb-
reich).
Strecker represents this interesting decomposition by the
equation
C42H84N PO9 + 3H20
Lecithine.
C3H9P06 + C5H15NO2 + C18H3402 + C16[[3202
Phospho-
glyceric acid.
Neurine.
Oleic
acid.
Palmitic
acid.
Neurine is an oxygenized base of which the constitution is
known. It is the hydrate of trimethyl-hydroxethylene-ammo-
nium (page 527).
(C2H+.OH)'
(CH3)3
N.OH
The chloride of this ammoniated base is formed by synthesis
by the action of ethylene chlorohydrate on trimethylamine (A.
Wurtz).
C2H+ SOH
CI + (CH3)³N
(C2H+.OH)} NCI
Trimethyl-hydroxethylene-
ammonium chloride.
Neurine is identical with a base which Strecker obtained
from the bile and designated as choline.
CHOLESTERIN.
C26H440
This body is largely diffused in the organism. It exists in
the bile, and is the principal constituent of most biliary cal-
culi. It is found also in small quantity in the serum of blood,
in the brain, in yolk of egg, pus, the liquid of hydrocele, etc.
Its solubility in alcohol and especially in ether, and the
facility with which it crystallizes from its solutions, permits.
its easy isolation. Cholesterin ordinarily deposits in thin and
brilliant, rhombic plates. It melts at 145°, and can be sub-
limed, out of contact with air, at 360°.
It forms neutral compounds with acids, analogous to the
ethers; it seems to be a monatomic alcohol.
The principal organic constituents of the bile are two com-
plex acids, both nitrogenized, and one of which contains sul-
phur. These are glycocholic and taurocholic acids. They are
672
ELEMENTS OF MODERN CHEMISTRY.
not contained in the bile of all animals, and are generally ex-
tracted from that of the ox. They enter into the composition
of human bile, which contains in addition coloring matters
of which the most important is bilirubin. We will briefly
describe these bodies.
GLYCOCHOLIC ACID.
C26 H 43 NO6
This body exists in the bile in the form of sodium glycocho-
late, which salt may be obtained in crystals from ox's bile.
The latter is decolorized by animal charcoal, filtered, the
liquid evaporated, and the residue perfectly dried and dissolved
in absolute alcohol; the solution is introduced into a flask, and
ether is cautiously added so that the two liquids may not mix,
but form two layers. The latter gradually mingle and the
sodium glycocholate deposits in crystals (Plattner).
When dilute sulphuric acid is added to a solution of this
salt, a cloud is formed, and glycocholic acid is soon deposited
in fine needles.
This acid is only slightly soluble in water and ether, but dis-
solves in alcohol. It is dextrogyrate (Hoppe-Seyler). By the
action of hydrochloric acid, it is decomposed into cholalic acid
and glycocol (Strecker).
C26 H43NO6 + H2O
Glycocholic acid.
C24H1005+
Cholalic acid.
C²H³NO²
Glycocol.
Cholalic Acid exists in the amorphous state and crystallized.
It deposits from its ethereal solution in four-sided prisms,
beveled at the ends, and containing two molecules of water of
crystallization. By boiling with acids, it is converted into a
resinous body which Berzelius called dyslysin.
C24H4005
C24H3603 + 2H2O
Dyslysin.
TAUROCHOLIC ACID.
C26 H 45 NSO7
The sodium salt of this acid remains dissolved in the ethe-
real solution from which sodium glycocholate has deposited.
It has not yet been obtained crystallized. It is dextrogyrate.
When boiled with dilute acids, or with alkalies, it breaks up
into cholalic acid and taurine (Strecker).
BILIRUBIN-BILIVERDIN.
673
C26H45NSO + H2O
Taurocholic acid.
C²+H¹005 + C²H¹NSO³
Cholalic acid.
Taurine.
Taurine, which was discovered by Leopold Gmelin, has
already been described (page 528).
BILIRUBIN.
C16H18N203
This substance exists in human bile and in biliary calculi.
It may be extracted from the latter, which contain it as calcu-
lary pigment. They are crushed, and exhausted, first with
ether, which removes the cholesterin, then with boiling water,
and finally with chloroform. The coloring matter remains in
the residue as a calcareous combination; this is decomposed
by adding hydrochloric acid, evaporating to dryness, and ex-
hausting the dried residue with chloroform. After evaporation,
the chloroform solution leaves a residue which contains, inde-
pendently of bilirubin, three other biliary pigments which we
will only mention: biliprasin, bilifuscin, and bilihumin. Alco-
hol dissolves the bilifuscin from this residue, and the new
residue is exhausted with chloroform, which takes up the bili-
rubin, which alcohol precipitates in orange-colored flakes from
the chloroform solution.
Bilirubin is obtained in small, dark-red crystals by evapora-
tion of its solution in chloroform. It is insoluble in water, and
very slightly soluble in ether and alcohol, but dissolves in chlo-
roform, benzol, and carbon disulphide. It is very soluble in
the alkalies, forming an orange-red solution, which becomes
pure yellow on addition of water, and from which hydrochloric
acid precipitates bilirubin. The ammoniacal solution of bili-
rubin gives precipitates with calcium chloride, barium chloride,
and lead acetate.
BILIVERDIN.
C16H18N204
When a solution of bilirubin in sodium hydrate is agitated
with air, it absorbs oxygen and becomes green. Hydrochloric
acid precipitates biliverdin from the solution.
It is a bright green powder, insoluble in water, ether, and
chloroform, but soluble in alcohol. It contains one more atom
of oxygen than bilirubin.
2D
57
674
ELEMENTS OF MODERN CHEMISTRY.
We
e may add that other coloring matters have also been
derived from bile. They are bilifuscin, C6H20N2O4, biliprasin,
C6H22N2O", and bilihumin.
CREATINE.
C4H9N3O2 + H2O
This body was discovered by Chevreul in meat broth. It
exists ready formed in the muscles, and passes into the extract
of meat. It may be prepared by treating the solution of this
extract with basic acetate of lead, filtering, freeing the filtrate
from excess of lead by hydrogen sulphide, and evaporating the
solution at a gentle heat until it crystallizes. The crystals are
separated from the mother-liquor, and alcohol added to the
latter precipitates a fresh quantity of creatine (Neubauer.)
Creatine crystallizes in brilliant, colorless, oblique rhombic
prisms, containing one molecule of water, which they lose at
100°, becoming opaque.
By the action of acids or by long boiling with water, crea-
tine is converted into creatinine.
C4H9N³O²
Creatine.
C'H'N³O + H2O
Creatinine.
When creatine is boiled with baryta-water, it is converted
into sarcosine, ammonia being disengaged and barium carbon-
ate precipitated at the same time. It is generally considered
that the ammonia and carbon dioxide are produced in this case
at the expense of urea, which is formed directly by the decom-
position of creatine.
CH³N³O² + H2O
Creatine.
C¹³H¹NO² + CH¹N²O
Sarcosine.
Urea.
Sarcosine is methylglycocol. It is isomeric with lactamide
and alanine. It may be obtained artificially by treating mono-
chloracetic acid with methylamine (Volhard.)
C2H2C1O.OH + CH3.NH2 C2II20<NH(CH3)
Monochloracetic acid. Methylamine.
OH
Sarcosine.
+
HCI
Volhard has made the synthesis of creatine by the action of
cyanamide on sarcosine. Cyanamide, CN.NH2, represents am-
monium cyanate less the elements of water.
CN²H² + C³H'NO²
Cyanamide.
Sarcosine.
C4H9N³O²
Creatine.
CREATININE.
675
CREATININE.
C4H7N30
This body exists in muscular tissue independently of creatine.
It may be precipitated from the mother-liquor from which the
latter body has deposited, by adding an alcoholic solution of
zinc chloride, which forms a crystalline combination with the
creatinine.
Creatinine crystallizes in oblique rhombic prisms. It is much
more soluble in alcohol than creatine. It has basic properties,
and forms a crystallizable compound with hydrochloric acid.
Creatine and creatinine have been found not only in the
muscles, but in small quantities in the brain, blood, and urine.
Among the products of disassimilation we may also mention :
Leucine, CHNO2, which belongs to the homologous series
of glycocol, and is found in many organs, especially in the
pancreas, the salivary glands, the spleen, and the liver (page
546).
Tyrosine, CH"NO", a body crystallizing in fine needles
may be obtained from the pancreas and the spleen (page 631).
It is known also that leucine and tyrosine may be obtained
directly by the action of alkalies upon complex nitrogenized
matters (page 661).
Hippuric acid, C'HºNO³, the origin of which has already
been indicated (page 627).
Uric acid, CH¹N*O", which exists in small quantity in
human urine, and which constitutes a large proportion of the
urine of birds and reptiles (page 559).
Allantoin, CH NO³, a product of the oxidation of uric acid,
which Vauquelin and Buniva formerly extracted from the am-
niotic liquor of the cow, and which has also been found in the
urine of young calves (page 563).
Various other products are related to uric acid. They are:
Xanthine, CH'N'O", a yellow matter, which Proust discov-
ered in certain rare calculi (xanthic calculi), and which has
also been found in small quantity in the muscles, pancreas, liver,
and urine.
57*
676
ELEMENTS OF MODERN CHEMISTRY.
Hypoxanthine or sarcine, CH*N*O, a white, amorphous sub-
stance which Scherer obtained from the spleen, and of which
Strecker has noticed the existence in muscular tissue. Hypo-
xanthine forms a crystallizable combination with hydrochloric
acid. It presents interesting relations of composition with xan-
thine and uric acid.
Uric acid
Xanthine
Hypoxanthine
•
C5H N403
C5H+N+02
C5 H4N40
When hypoxanthine is boiled with nitric acid, it is converted
into a nitrogenized body. By the action of reducing agents,
such as ferrous sulphate, this nitrogenized body is converted
into guanine, CH³Ñ³O. The latter body was first obtained
from guano. It has been found in the tissue of the pancreas.
MEASURES OF WEIGHT.
1 Milligramme
1 Centigramme
1 Decigramme
1 Gramme
1 Decagramme
1 Hectogramme
1 Kilogramme
1 Grain
=
1 Oz. Troy
GRAINS.
OUNCES TROY
480 GRAINS.
POUNDS
AVOIRDUPOIS.
0.01543
0.000032
0.0000022
0.15432
0.000321
0.0000220
1.54323
0.003215
0.0002204
15.43234
0.032150
0.0022046
154.32349
0.321507
0.0220462
1543.23488
3.215072
0.2204621
15432.34880
32.150726
2.2046212
1 Lb. Avoirdupois
0.064799 grammes.
31.103496
0.453495 kilogrammes.
1 Cubic Centimetre of water weighs 1 gramme.
To convert Centigrade degrees into Fahrenheit degrees, multiply by 9 and
divide by 5; add 32°.
To convert Fahrenheit degrees into Centigrade degrees, subtract 32°, then
multiply by 5 and divide by 9.
1 Metre
1 Centimetre
39.370708 inches.
0.39370 (C
1 Millimetre
0.03937
1 Inch
2.539954 centimetres.
57*
677
INDEX.
Acetamide, 505.
Acetates, 495.
Acetic anhydride, 499.
Acetone, 503.
Acetones, 420.
Acetonitrile, 449.
Acetyl chloride, 502.
Acetylene, 520.
Acid, 42.
acetic, 492.
aconitic, 559.
acrylic, 512.
alloxanic, 561.
amidacetic, 544.
B-amidopropionic, 546.
anisic, 631.
anthranilic, 634.
antimonic, 189.
arsenic, 182.
Acid, elaidic, 512.
ethylnitrolic, 467.
ethylphosphinic, 485.
ethylsulphuric, 468.
formic, 490.
fumaric, 553.
gallic, 632.
gluconic, 570.
glutamic, 659.
glyceric, 543.
glycocholic, 672.
glycollie, 537.
glyoxylic, 538.
hippuric, 627.
hydracrylic, 543.
hydriodic, 132.
hydrobromic, 128.
hydrochloric, 116.
hydrocyanic, 431.
hydrofluoric, 136.
arsenious, 179.
aspartic, 554.
benzoic, 626.
boric, 193.
bromic, 130.
butyric, 508.
campholic, 601.
camphoric, 602.
caproic, 510.
carbonic, 206, 209.
cerotic, 511.
chlorethylsulphurous, 528.
chloric, 125.
chlorous, 123.
cholalic, 672.
chromic, 347.
cinchonic, 654.
citraconic, 559.
citric, 558.
crotonic, 512.
cyanic, 438.
cyanuric, 442.
hydrofluosilicic, 198.
hydrosulphurous, 100.
hypobromous, 129.
hypochlorous, 122.
hypophosphorous, 171.
hyposulphuric, 109.
hyposulphurous, 109.
iodic, 134.
iodopropionic, 508.
isethionic, 528.
. isobutyric, 509.
isophthalic, 638.
itaconic, 559.
lactic, 539.
leucic, 546.
maleic, 553.
malic, 552.
malonic, 536.
manganic, 343.
margaric, 511.
meconic, 646.
dialuric, 562.
dibromosuccinic, 551.
digallic, 590.
mellic, 593.
mesoxalic, 561.
metaphosphoric, 175.
679
680
ELEMENTS OF MODERN CHEMISTRY.
Acid, methylnitrolic, 451.
monobromosuccinic, 551.
monochloracetic, 498.
nitric, 157.
nitrohydrochloric, 160.
oleic, 512.
opianic, 650.
oxalic, 547.
oxamic, 550.
oxybenzoic, 631.
palmitic, 511.
parabanic, 562.
paralactic, 539. 541.
paratartaric, 558.
paroxybenzoic, 631.
pentathionic, 97.
perbromic, 130.
perchloric, 125.
perchromic, 87.
periodic, 135.
permanganic, 344.
persulphuric, 110.
phosphoric, 173.
phosphorous, 172.
phthalic, 637.
picramic, 607.
pierie, 607.
propionic, 507.
purpuric, 563.
pyrogallic, 633.
pyrophosphoric, 174.
pyrotartaric, 555.
pyruvic, 555.
quinic, 651.
quinolic, 653.
ruberythric, 642.
salicylic, 629.
silicic, 199.
Acid, valerie, 510.
Acids, diatomic, 428.
fatty, 488, 505.
monatomic, 418.
polyatomic, 536.
Aconitine, 655.
Acrolein, 512.
Affinity, 11.
Air, 63.
Alanine, 545.
Albumen, 660.
Albuminoid matters, 657.
Alcohol radicals, 425.
Alcohol, allyl, 478.
amyl, 175.
benzyl, 623.
butyl, 474.
cetyl, 477.
ethyl, 455.
heptyl, 477.
hexyl, 477.
methyl, 447.
octyl, 477.
propyl, 474.
Alcohols, diatomic, 427, 521.
monatomic, 417, 444, 472.
polyatomic, 429, 564.
primary, secondary, tertiary,
472.
Aldehyde, acetic, 505.
anisic, 631.
benzoic, 624.
butyric, 509.
crotonic, 512.
formic, 492.
salicylic, 628.
Aldehydes, 420.
Aldol, 501.
stannic, 354.
stearic, 511.
succinic, 550.
sulphocarbonic, 215.
sulphosulphuric, 109.
sulphuric, 102.
66
fuming, 108.
sulphurous, 97.
tannic, 589.
tartaric, 554.
tartronic, 556.
taurocholic, 672.
terephthalic, 638.
tetrathionic, 97.
trichloracetic, 499.
trithionic, 97.
uric, 559, 675.
Alizarin, 611.
Alkaloids, 643.
Allantoin, 563.
Alloxan, 561.
Alloxantin, 562.
Alloys, 236.
Allyl alcohol, 478.
bromide, 518.
iodide, 478.
sulphide, 478.
sulphocyanate, 478.
Alum, 315.
Aluminium, 313.
chloride, 314.
oxide, 314.
silicates, 317.
sulphate, 315.
INDEX.
681
Amalgams, 236.
Amides, 421.
Amines, 422, 479.
Ammonia, 139.
action of Cl and I, 143.
action of potassium, 145.
Ammonium amalgam, 145.
carbonate, 148.
chloride, 146.
cyanate, 440.
formate, 491.
nitrate, 148.
oxalate, 549.
sulphate, 149.
sulphide, 147.
sulphocyanate, 444.
sulphydrate, 147.
theory of, 146.
Amygdalin, 587.
Amyl alcohols, 475.
chloride, 476.
iodide, 476.
oxide, 476.
Amylenes, 519.
bromides, 520.
Anilides, 609.
Aniline, 608.
colors, 613.
salts, 608.
Anisic compounds, 631.
Anthracene, 640.
Anthracite, 202.
Anthraquinone, 641.
Antimonio-potassium tartrate, 557.
Antimony, 185.
antimonate, 188.
oxide, 188.
pentachloride, 187.
pentasulphide, 190.
pentoxide, 189.
trichloride, 186.
trisulphide, 189.
Apomorphine, 648.
Aromatic compounds, 590.
Arsenic, 176.
chloride, 179.
disulphide, 183.
pentasulphide, 184.
pentoxide, 182.
trioxide, 179.
trisulphide, 183.
Arsines, 423.
Asparagin, 553.
Atomic heats, 34.
Atomic theory, 27.
Atomicity, theory of, 222.
Atropine, 656.
Aurin, 608.
Australine, 598.
Azobenzol, 604.
Azoxybenzol, 604
Barium, 302.
carbonate, 304.
chloride, 303.
dioxide, 302.
nitrate, 303.
oxide, 302.
sulphate, 304.
sulphide, 303.
tests, 304.
Beer, 579.
Benzamide, 627.
Benzol, 602.
monobromo-, 603.
monochloro-, 603.
Benzoyl hydride, 624.
chloride, 625.
Benzyl alcohol, 623.
aldehyde, 624.
chloride, 620.
Benzylamine, 624.
Berthollet's laws, 265.
Bilirubin, 673.
Biliverdin, 673.
Bismuth, 349.
chloride, 350.
nitrate, 351.
oxide, 350.
tests, 351.
Bituminous coal, 202.
Borncol, 602.
Boron, 191.
chloride, 192.
fluoride, 193.
oxide, 193.
Boro-potassium tartrate, 558.
Bromine, 127.
Brucine, 654.
Bunsen burner, 221.
Butane, 455.
Butyl alcohols, 474.
Butylenes, 518.
Butyral, 509.
Butyrone, 509.
Cacodyl, 453.
Cadmium, 337.
iodide, 337.
oxide, 337.
2D*
682
ELEMENTS OF MODERN CHEMISTRY.
Cadmium, sulphate, 338.
sulphide, 337.
Cæsium, 300.
Caffeine, 657.
Calcium, 305.
carbonate, 307.
chloride, 307.
Cobalt, oxides, 338.
sulphate, 339.
tests, 339.
Cocaine, 655.
Codeine, 648.
Combination, laws of, 23-27.
Combustion, 58.
hydrate, 305.
Conine, 644.
hypochlorite, 309.
Copper, 368.
lactate, 542.
acctates, 496.
nitrate, 307.
alloys, 375.
oxide, 305.
sulphate, 308.
tests, 310.
Camphenes, 599.
Camphor, 600.
artificial, 599.
Carbamide, 440.
Carbon, 200.
dioxide, 209.
disulphide, 215.
estimation of, 406.
monoxide, 207.
compounds of, 438.
oxysulphide, 216.
tetrachoride, 419.
sesquichloride, 516.
Carbonates, 275.
Carbonyl chloride, 208.
Carbylamines, 450, 465.
carbonates, 374.
chlorides, 372.
oxides, 371.
sulphates, 373.
sulphides, 372.
tests, 375.
Cotarnine, 650.
Creatine, 674.
Creatinine, 675.
Cresols, 621.
Cupellation, 359, 389.
Cyanobenzol, 605.
Cyanogen, 430.
bromide, 437.
chlorides, 436.
iodide, 437.
Cymene, 599.
Dextrin, 581.
Diamines, 428.
Casein, 667.
Cellulose, 584.
Charcoal, 202.
absorbent properties of, 204.
Chloral, 502.
Chlorides, 246.
monatomic, 415.
of acid radicals, 421.
Chlorine, 112.
and Br and I, analogies, 136.
peroxide, 124.
Chloroform, 448.
Diamond, 201.
Diazoamidobenzol, 612.
Diazobenzol compounds, 610.
Dichlorhydrin, 531.
Dimethylarsine, 453.
Dioxindol, 636.
Ductility, 233.
Diphenylamine, 614.
Diphenylketone, 627.
Dulcite, 566.
Elementary analysis, 406.
Chlorotoluols, 620.
Chlorous anhydride, 123.
Cholesterin, 671.
Chondrin, 668.
Chromates, 347.
Chromium, 346.
chlorides, 348.
oxides, 346.
Cinchona bark, 650.
Cinchonine, 653.
Citrine, 600.
Cobalt, 338.
chloride, 339.
Elements, table of, 39.
Emulsin, 587.
Epichlorhydrin, 531.
Erythrite, 565.
Ethane, 455.
Ether, 459.
acetylacetic, 498.
Kay's, 449.
Ethers compound, 419.
simple, 454.
Ethyl acetate, 497.
carbamate, 470.
INDEX.
683
Ethyl carbonate, 469.
carbylamine, 465.
chloride, 463.
chlorocarbonate, 470.
cyanate, 468.
cyanide, 465.
hydrate, 455.
iodide, 464.
nitrate, 167.
nitrite, 466.
oxalate, 549.
oxide, 459.
sulphate, 469.
sulphide, 463.
sulphydrate, 462.
Ethylamines, 482.
Ethylene, 513.
acetates, 525.
bromide, 515.
chlorhydrate, 524.
chloride, 515.
chloro-derivatives, 515.
diamines, 527.
hydrate, 523.
iodide, 515.
nitrates, 525.
oxide, 525.
bases from, 526.
Ethylhydrazine, 480.
Ethylidene chloride, 501, 516.
Ethylphosphines, 483.
Fats, natural, 532.
Fermentation, 576.
Ferric chloride, 327.
oxide, 326.
sulphate, 329.
Ferro-potassium tartrato, 557.
Ferrous chloride, 327.
lactate, 542.
oxide, 325.
sulphate, 328.
Fibrin, 662.
Flame, 218.
Fluorescein, 638.
Fluorine, 136.
Formates, 491.
Formonitrile, 432.
Formulæ, constitutional, empirical,
rational, 419.
Fulminates, 452.
Functions, organic, 414.
Gelatin, 667.
Gilding, 394.
Globulin, 667.
Glucosan, 568.
Glucose, 567.
Glucosides, 586.
Glycerin, 529.
ethers of, 530.
Glycocol, 544.
Glycogen, 583.
Glycol, 523.
ethers of, 427.
Glycols, 427, 521.
Glyoxal, 538.
Gold, 391.
assay, 395.
chlorides, 393.
oxides, 393.
Graphite, 201.
Guanine, 676.
Gum arabic, 584.
tragacanth, 584.
Gums, 583.
Gun-cotton, 586.
Hematin, 666.
Hemoglobin, 664.
Hexamethylbenzol, 619.
Homologous bodies, 405.
Hydrazine, 480.
Hydrazobenzol, 604.
Hydrocarbons, CnH2n+2, 415, 470.
Call²n, 517.
CuII2n-2, 520.
IIydrogen, 48.
absorption by palladium, 51.
antimonide, 186.
arsenide, 178.
dioxide, 85.
estimation of, 406.
persulphide, 96.
phosphide, 165.
silicide, 195.
sulphide, 92.
Hydroquinone, 616.
Ilydroxylamine, 149.
Hypochlorous anhydride, 122.
Hypoxanthine, 676.
Indigo, 633.
white, 634.
Indium, 336.
Indol, 636.
Inosite, 571.
Gallium, 335.
Gay-Lussac's law, 27.
Inulin, 583.
68+
ELEMENTS OF MODERN CHEMISTRY.
Iodine, 130.
oxides, 134.
Iron, 318.
carbonate, 329.
cast, 323.
chlorides, 327.
lactate, 542.
oxides, 325.
soft, 322.
sulphates, 328.
sulphides, 327.
tests, 330.
Isatin, 635.
Isomerism, 412.
Isomorphism, 37, 255.
Isopropyl iodide, 474.
Isoturpentine, 600.
Kay's ether, 449.
Lactamide, 542.
Lactates, 542.
Lactose, 574.
Lamp-black, 203.
Lead, 357.
acetates, 496.
carbonate, 366.
chloride, 364.
chromate, 367.
dioxide, 362.
iodide, 364.
monoxide, 361.
nitrate, 365.
red oxide, 362.
sulphate, 365.
sulphide, 363.
tests, 367.
Lecithine, 670.
Leucanilines, 612.
Leucine, 546, 675.
Levulosan, 570.
Levulose, 570.
Lignite, 202.
Lime, 305.
Lithium, 299.
Magnesium, 310.
carbonate, 312.
citrate, 559.
chloride, 311.
oxide, 311.
sulphate, 312.
tests, 313.
Malleability, 233.
Maltose, 575.
Manganese, 342.
carbonate, 345.
dioxide, 342.
oxides, 342.
sulphate, 344.
tests, 345.
Mannitan, 566.
Mannite, 566.
Marsh's apparatus, 181.
Marsh gas, 445.
Matches, 165.
Mercur-ethyl, 486.
Mercuric chloride, 380.
iodide, 381.
Mercur-methyl, 486.
Mercurous chloride, 379.
iodide, 381.
Mercury, 375.
cyanide, 433.
fulminate, 452.
nitrates, 382.
oxides, 378.
sulphates, 383.
sulphide, 378.
tests, 383.
Mesitylene, 505,
Metaldehyde, 501.
Metallic carbonates, 275.
chlorides, 246.
hydrates, 244.
nitrates, 271.
oxides, 238.
sulphates, 273.
sulphides, 245.
Metals, classification of, 277.
general properties of, 231.
Metamerism, 412.
Methane, 445.
Methylamines, 481.
Methylbenzol, 618.
Methyl bromide, 448.
chloride, 448.
compounds, 445.
cyanide, 449.
hydrate, 447.
iodide, 448.
nitrate, 450.
nitrite, 450.
oxide, 447.
salicylate, 630.
Mineral waters, 82.
Minium, 362.
Molecular weights, determination
of, 410.
Monobromobenzol, 603.
INDEX.
685
Monochlorobenzol, 603.
Monochlorhydrin, 531.
Morphine, 647.
Murexide, 563.
Myosin, 663.
Naphthalene, 639.
Naphthol, 640.
Naphthylamine, 640.
Narceine, 646.
Narcotine, 649.
Neurine, 527, 671.
Nickel, 340.
chloride, 341.
oxides, 340.
sulphate, 341.
tests, 341.
Nicotine, 645.
Palmitine, 533.
Papaverine, 646.
Paraconine, 645.
Paraldehyde, 501.
Persulphuric oxide, 110.
Phenanthrene, 641.
Phenol, 605.
Phloretin, 589.
Phloridzin, 588.
Phloroglucin, 589, 618.
Phosphines, 423.
Phosphoric anhydride, 173.
Phosphorus, 161.
bromide, 169.
iodide, 170.
oxychloride, 169.
pentachloride, 168.
pentoxide, 173.
sulphides, 176.
sulphochloride, 159.
trichloride, 168.
Nitrates, 271.
Nitrethane, 466.
Nitric anhydride, 157.
Nitrobenzol, 604.
Pinacolin, 505.
Nitroferrocyanides, 436.
Pinacone, 522.
Nitrogen, 138.
Platinum, 395.
chloride, 144.
chlorides, 397.
dioxide, 153.
estimation of, 406.
group, gen. considerations, 190.
iodide, 145.
monoxide, 151.
Plumbago, 201.
Polymerism, 412.
Populin, 588.
Potassamide, 145.
pentoxide, 157.
peroxide, 155.
trioxide, 154.
Nitroglycerin, 530.
Nitromethane, 450.
Nitrosyl chloride, 161.
Nitrotoluols, 620.
Nitryl, chloride and bromide, 156.
Nomenclature, 37.
Notation, 37.
Nornarcotine, 650.
Oils, essential, 596.
Olcin, 533.
fatty and drying, 533.
Opium, 646.
Orcin, 486, 621.
Organo-metallic compounds, 423.
Orpiment, 183.
Oxalates, 548.
Oxamide, 549.
Oxindol, 636.
Oxygen, 54.
Ozone, 59.
Oxyphenols, 614.
Potassium, 282.
acetate, 495.
acid-sulphate, 288.
bromide, 286.
carbonates, 289.
chlorate, 288.
chloride, 285.
chromate, 347.
cyanate, 439.
cyanide, 433.
dichromate, 317.
ferricyanide, 435.
ferrocyanide, 434.
hydrate, 283.
iodide, 285.
methylate, 447.
nitrate, 286.
oxalates, 549.
oxides, 283.
perchlorate, 289.
permanganate, 344.
sulphate, 288.
sulphides, 284.
sulphocyanate, 444.
tartrates, 556.
tests, 290.
58
686
ELEMENTS OF MODERN CHEMISTRY.
Pottery, 317.
Propionitrile, 465.
Propyl alcohols, 474.
glycols, 529.
iodide, 474.
Propylene, 518.
Prussian blue, 435.
Pseudomorphine, 617.
Purpurin, 643.
Pyrocatechin, 615.
Pyrogallol, 618.
Quinine, 651.
Quinone, 616.
Radicals, monatomic, 425.
polyatomic, 426.
Realgar, 183.
Resorcin, 615.
Respiration, 669.
Richter's laws, 253.
Rochelle salt, 556.
Rosaniline, 611.
Rubidium, 300.
Saccharose, 571.
Safety-lamp, 219.
Salicin, 588.
Salicyl hydride, 628.
Saligenin, 588, 628.
Salts, 43, 250.
action of acids, 265.
bases, 267.
electricity, 262.
heat, 261.
metals, 264.
salts, 268, 270.
water, 256.
neutral, acid, and basic, 252.
Saponification, 535.
Sarcine, 676.
Sarcosine, 674.
Selenium, 111.
Silica, 199.
Silicon, 194.
chloride, 196.
fluoride, 197.
oxide, 199.
Silver, 384.
acetate, 497.
assay, 389.
chloride, 387.
fulminate, 452.
fulminating, 387.
iodide, 388.
Silver, nitrate, 388.
oxide, 387.
sulphide, 387.
tests, 389.
Silvering, 389.
Soap, 534.
Sodium, 291.
acetate, 496.
acid-carbonate, 298.
acid-sulphate, 295.
borate, 298.
carbonate, 295.
chloride, 293.
hydrate, 292.
hydrosulphite, 100.
hyposulphite, 109.
nitroferrocyanide, 436.
oxides, 292.
phosphates, 298.
sulphate, 294.
sulphide, 292.
tests, 299.
Scrbin, 571.
Sorbite, 567.
Specific heat, 34.
Spectrum analysis, 300.
Stannethyls, 487.
Starch, 580.
Stearin, 533.
Stearin candles, 534.
Steel, 323.
Stibines, 423.
Strontium, 304.
Strychnine, 654.
Succinic anhydride, 551.
Succinyl chloride, 551.
Sugar, cane, 571.
grape, 567.
inverted, 574.
milk, 574.
Sugars, 567.
Sulphates, 273.
Sulphur, 88.
chlorides, 126.
soft, 90.
Sulphuric anhydride, 101.
Sulphurous anhydride, 97.
Sulphuryl chloride, 100, 106.
Supersaturation, 259.
Syntonin, 664.
Tannin, 589.
Tartar-emetic, 557.
Tartrates, 556.
Taurine, 528.
INDEX.
687
Tellurium, 111.
Torebene, 599.
Terpilene, 600.
Terpin, 598.
Tetrachlorethylene, 516.
Tetramethylammonium, 482.
Tetrethylammonium, 483.
Thallium, 302.
Thebaine, 646.
Theine, 657.
Theobromine, 656.
Tin, 352.
dichloride, 355.
oxides, 354.
sulphides, 355.
tests, 357.
tetrachloride, 356.
Toluidines, 622.
Urethane, 470.
Verdigris, 497.
Vermillion, 379.
Vinegar, 494.
Water, 70.
analysis, 71.
mineral, 82.
natural state, 79.
synthesis, 72.
Wax, 477.
Wine, 578.
Wood-spirit, 417.
Xanthine, 675.
Xyloidin, 582.
Xylols, 037.
Toluol, 618.
Tribenzylamine, 624.
Yeast, 576.
Trichlorhydrin, 532.
Triethylamine, 483.
Zinc, 330.
Trimethylamine, 482.
Trimethylcarbinol, 475.
Trinitrophenol, 607.
Turpentine, 596, 598.
Tyrosine, 631.
Urea, 440.
Ureas, compound, 443.
chloride, 333.
hydracrylate, 543.
lactate, 542.
oxide, 332.
sulphate, 333.
sulphide, 333.
tests, 334.
Zinc-ethyl, 486.
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A MAGNIFICENT WORK.
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