MANUAL OF CHEMICAL ANALYSIS AS APPLIED TO THE EXAMINATION OF MEDICINAL CHEMICALS. A GUIDE FOR THE DETERAIINA TION OF THEIR IDENTITY AND QUALITY, AND FOR THE DETECTION OF IMPURITIES AND ADULTERATIONS. FOR THE USE OF PI-IARMACEUTISTS, PHYSICIANS, DRUGGISTS, AND MANUFACTURING CHEMISTS, AND OF PHARMACEUTICAL AND MEDICAL STUDENTS. BY FREDERICK;. HOFFMANN, PH. D., PHARMACEUTIST IN NEW YORK. NEW YORK: D. APPLETON AND COMPANY, 549 & 551 BROADWAY. 1873. 'ENTEIED, according to Act of Congress, in the year 1872, by FREDERICK IIOFFMANN, In the Office of the Librarian of Congress, at Washington. PRE FACE. ALTHOUGH the preparation of most medicinal chemicals has passed away from the laboratory of the pharmaceutist, and is successfully conducted on a commercial scale in manufacturing establishments, yet the responsibility for the identity and quality of medicines, and of the substances used in their preparation, rests properly and legally with those who prepare, compound, and dispense them. It is therefore the duty of the pharmaceutist and the dispensing practitioner of medicine, as also, to a considerable extent,. of the druggist and the manufacturing chemist, to examine the medicinal chemicals of commerce as to their identity, quality, and purity. In the exercise of this duty, they have frequent occasion to resort for information to references now widely scattered through chemical, pharmaceutical, and medical manuals and journals; since our literature, although of vast and increasing extent, and crystallizing more and more into distinct branches, is still wanting in a special guide for ready reference in the application of chemical analysis to such examinations. In the present volume I have endeavored to supply this want, in a manner and to an extent which, it is hoped, will confine the work- within the precise limits of requirement, without detracting from its general scope and its practical usefulness. iv PREFACE. Since chemical tests and examinations bear upon and involve the methods of systematic chemical analysis, and as these cannot be described in each particular instance, I have deemed it expedient to preface the volume with a few notes on operations and reagents, and on a few important general tests, and to present a brief outline of a simple course of qualitative analysis for the systematic and progressive recognition of such substances as are met with in the medicinal chemicals. A brief guide has also been added, for the volumetric estimation of those compounds to which this mode of examination is especially applicable. Upon these preliminaries is based the subsequent description of the physical and chemical properties and relations of the medicinal chemicals and their preparations, and of the methods employed for establishing their identity, and for ascertaining their quality and purity. It has been compiled with special reference to the fifth decennial edition of the United States Ptlarmacopceia, to the latest British Pharmacopoeia, and to the Pharmacopcea Germanica of 1872. It has been brought within the briefest possible compass, with the view to furnish a concise and trustworthy guide, combining easy execution, simple apparatus, and economy of time, with the greatest attainable accuracy. A glance at the table of contents will at once give an idea of the arrangement of the subject-matter, and of the scope as well as the limitations of the work. Chemical notation, although the most precise and definite, and at the same time the most comprehensive, method of expressing the constitution of compounds, has been omitted, for want of unanimity and absolute certainty in this particular point of chemical philosophy. The weights used are, with the exception of the volumetric tests and examinations, those of the troy scale, and the word "'parts " means invariably parts by this weight, unless where volume-parts are expressly stated. Temperatures are denoted, PREFACE. V in accordance with general adoption, by degrees of the centigrade scale. Comparative tables of the two scales, and of the troy and metric weights, are given at the end of the volume. In preparing this compendium, I have consulted, and at times made free use of, a number of standard works, and periodicals of the kindred literature. I have, however, felt compelled, not without hesitation, to omit the introduction of references, which would have required much space, and would have greatly increased the size of the volume, without affording a corresponding advantage. Though well aware of the shortcomings and imperfections of the work, I nevertheless venture to hope that it will meet with kind consideration, and will prove both serviceable and stimulating in a province not yet duly appreciated or deservedly cultivated. This hope is the stronger, as the work appears at a time when the rapid advance of both sciences and arts, the drift of public sentiment, and the consequently increasing obligations of the pharmaceutist and the physician, all tend toward higher qualifications, and necessitate also, among other attainments, a more extended exercise of knowledge and skill in chemical and microscopical investigation. I trust, moreover, to the candor of critics, who, while it is easy to detect faults in a volume of this nature and scope, in which perfection would scarcely be attainable even under more favorable circumstances, can at the same time appreciate the difficulties of a work that has been written in a pursuit and position which exclude, almost wholly, the quiet reflection and undisturbed study requisite for the prosecution of scientific or literary labor. In conclusion, I desire to express my obligations and thanks to Prof. D. S. Martin, of Rutgers Female College, for his kind assistance in the revision of the proofs. NEW YORK, February, 18'73. CONTENTS. PART FIRST: PAGE OPERATIONS AND REAGENTS,.............................. 15 REAGENTS,........................................... 20 COURSE OF QUALITATIVE ANALYSIS,.................... 34 Preliminary Examination,.............................. 35 Solution................................................... 37 Examination for Bases,................... 38 Examination for Acids,............................ 44 Table of the Deportment of the Compounds of the Common Metals with some of the General Reagents,..................... 49 VOLUMETRIC ANALYSIS,................................... 50 ]Estimation of Alkalies, 56 Estimation of Acids,........................................ 60 Estimation of Iodides and Bromides,................ 62 Estimation of Arsenites and Hyposulphites.................... 63 Estimation of Iodine and Chlorine,............................ 63 PART SECOND. MEDICINAL CHEMICALS AND THEIR PREPARATIONS. Acetum,...................................................... 67 Acidum Aceticun,...................................... 69 " Arseniosum,........................................... 73 " Benzoicum,............ 75 " Boracicum,............................................ 78 " Carbolicum,............................................ 78 " Chromicum,................ 80 " Citricum,.......................... 80 " Gallicum,.................................... 82 " Hydrochloricum,.................................. 83 8 CONTENTS. PAGE Acidum Hydrocyanicum dilutum,............................... 88 " Lacticum,.............................................. 90 " Nitricum,............................................ 91 " Oxalicum,............................................. 95 " Phosphoricum........................................ 96 " Succinicum,.......................................... 102 " Sulphuricum.......................................... 104 Tannicum,........................................... 109 " Tartaricum,............................................ 110 " Valerianicum,......................................... 111 Aconitia,..................................................... 113 /ther,...................................................... 114.Ether Aceticus............................................ 116 Alcohol,...................................................... 118 Alcohol Amylicum,............................................ 122 Alumen,...................................................... 122 Aluminii Sulphas.............................................. 124 Amnmonii Benzoas,.......................................... 124 " Bromidum,........................................... 125 Carbonas,................... 126 " Chloridum,........................................... 127 " lodidum,............................................ 128 " Nitras,.............................................. 129 Phosphas,........................................... 130 " Valerianas,...... 131 Antimonii et Potassii Tartras,.................................... 131 " Oxidum..134 " Oxidurni........................................... 1 4 " Oxy-suIphuretum,.................................... 135 " Sulphuretuin nigrum.......................... 138 " " aurantiacum,............................. 140 Aqua Ammonie,............................................... 142 " Amygdalarum amararum................................. 146 " Chlori,.................................................. 147 " Destillata,............................................... 149 Argenti Nitras............................................... 150 " Oxidumn,........................... 154 " Arsenici Iodidum,...................................... 154 Atropia................................................... 155 Atropive Sulphas,.............................................. 155 Barii Chloridum,............................................... 156 Bismuthi et Ammonii Citras,................................... 157 " Subcarbonas,........................................ 158 " Subnitras,............................................ 159 " Valerianas,.......................................... 164 Bromum,.................................... 165 CONTENTS. 9 PAGE Cadmii Sulphas,............................................... 167 Calcii Carbonas praecipitata,....................................... 167 H" Hypophosphis............................................. 168 " Phosphas prwecipitata,.................................... 169 Calx Chlorinata,................................. 170 Carbonei Sulphuretum,......................................... 173 Cerii Oxalas,.................................................. 174 Chlorali Hydras,............................................ 175 Chloroformum,........................................ 178 Cinchoniwe Sulphas............................................ 181 Codeia,............. 182 Coffeia....................................................... 183 Colchicia,..................................................... 184 Conia,....... 185 Creasotum,.................................................... 186 Cupri Acetas................................................ 188 " Oxidum,........................ 189 " Sulphas............................................... 191 CupruIn Ammoniatum,......................... 193 Digitalinum............................. 194 Emetia....................... 195 Ferri Arsenias,................................................ 196 " Carbonas saccharata,..................................... 197 Chloridum,............................................. 198 " Citras,......... 200 et Ammnonii Chloridurn,............................... 201 (" " L" Citras,....................................... 201 ~" "'~ " Sulphas...................................... 202 " " " Tartras,..................................... 203 et Potassii Tartras,....................................... 204 " Quiniae Citras,......................................... 204 Ferrocyanidum,....................................... 206 " Hypophosphis............................................ 207 " lodidum,................................................ 208 Lactas,.................................................. 209 Oxidum Hydratum....................................... 210 " Magneticum,...211 " Phosphas,.. 212 Phosphas,.............................................. 212 ValePyrophosphas,........................................... 213 et Amnraonii Citras,......................... 214 " Subearbonas,....................... 214 " Sulphas,......................... 215 " Valerianas,......................... 217 Ferrum,............................................. 218 Glycerinum.................................................... 221 10 CONTENTS. PAGE iydrargyri Chloridum corrosivum............................... 225 " " mite,.................................... 226 " Cyanidunm,......................................... 228 " Iodidum rubrum,................................... 229 " " viride...................................... 231 ": Oxiduin flavum,..................................... 232'"' rubrm.. 232 Subitras,..................................... 235 " Sulphas fiava....................................... 236 " Sulphuretum rubrum,............................... 236 Hydrargyrum,................................................ 238 Ammoniatum,..................................... 240 Iodoformum,.................................................. 242 Iodum,.................... 243 Liquor Ammonii Acetatis...................................... 245 " Antimonii Chloridi,..................................... 246 Calcis,................... 247 i Ferri Acetatis,.......................................... 247 " " Nitratis,.......................................... 248 " " Snuiphatis......................................... 249 ": Hydrargyri Nitratis..................................... 250 " Plumbi Subacetatis,....................................... 251 Potassm............................................... 252 " Potassii Arsenitis,....................................... 254 Sode,.................................................. 254 Lithii Carbonas,.............................................. 256 Citras,.................................................. 257 Magnesia...................................................... 258 Magnesii Carbonas............................................ 259 " Snuiphas,............................................. 260 Manganesii Oxidum nigrum, 262 " Suiphas,........................................ 264 Morphia...................................................... 266 Morphie Acetas................................................ 271 IHydrochloras......................................... 271 " SuIp ulphas, 272 Nicotia,....................................................... 273 Oleum Amygdalarum amararum,.............................. 274 " Sinapis.................................................. 277 Plumbi Acetas,................................................ 278 Carbonas,............................................. 279 Iodidum,............................................... 281 " Nitras................................................. 282 " Oxidum,............................................ 282 " rubrum,....... 284 CONTENTS. 11 PAGE Potassii Acetas,................................................ 285'" Bicarbonas,............ 286 Bihromas,...287 i Bitartras,.............................................. 288 " Bromidum............................................ 290'" Carbonas cruda,........................................ 292 " " depurata,..................................... 294 " pura....................................... 295 " Chloras,.............. 297 " Hydras,............................................... 298 " cruda,......................................... 299 " Ferrocyanidum,........................................ 301 " lodidum,.............................................. 302 " Nitras,......... 306 " Permanganas,......................................... 307 " et Sodii Tartras,...................................... 308 " Sulphas,.............................................. 309 " Sulphuretum,............................................ 310 i" Tartras,................................................ 311 Quinia,....................................................... 312 Quiniae iydrochloras,..................................... 319 " Sulphas,.............................................. 320 " Tannas,................................................ 324 " Valerianas,............................................ 325 Quinoidinum,.................................. 326 Santoninum,................................................. 328 Sodii Acetas,................................................... 329 " Arsenias,...330 " Biboras,................................................. 331 " Bicarbonas,.............................................. 332 " Carbonas,............ 334 " Chloridum,............................................. 335 "' Hydras,............................................... 337 " Hypophosphis,.............. 339 " Hyposulphis............................................ 339 " Iodidum,.............................................. 341'" Nitras,................................................... 343 " Phosphas, i........ 345 i" Pyrophosphas,........................................... 346 " Sulphas................................................ 347 " Sulphis,................................................ 350 Spiritus ~Etheris nitrosi.................................. 351 Strychnia,................................................... 354 Strychnima Nitras,............................................. 357 " Sulphas,.......................................... 358 CONTENTS. PAGE Sulphur prmcipitatum,.......................................... 359 Sulphur sublimatum,............................ 361 Sulphuris Iodidum,............................................ 363 Veratria,..................................................... 364 Zinci Acetas,.............................................. 365 " Chloridum,............................................... 366 " Oxidum.................................................. 368 " Sulphas,................................................. 370' Valerianas,.................................... 372 Table of Elementary Bodies, with their Atomic Symbols and Weights,............................................... 377 Table for converting Degrees of the Centigrade Thermometer into Degrees of Fahrenheit's Scale....... 378 Table for converting Troy-weights into Metric Weights,........v... 380 Table for converting Metric Weights into Troy-weights,.. 381 INDEX,.......................................................38 PART FIRST. OPERATIONS AIND REAGENTS, INCLUDING A BRIEF OUTLINE OF A SYSTEMATIC COURSE OF CHEMICAL ANALYSIS, AND OF VOLUMETRIC ESTIMATION. OPERATIONS ANDT REAGENTS. OPERA TI ONS. THE operations in simple tests and chemical examinations must be supposed to be familiar to the pharmaceutist, the druggist, the pharmaceutical manufacturer, and the physician; the description of them, therefore, can properly be left to the manuals of analytical and pharmaceutical chemistry, and may be confined in this volume to a few practical hints in relation to some of the principal operations. Solutions.-The common solvent, water, has to be used distilled, and this fact is to be understood throughout this work; neither rain-water nor spring-water, however pure it may appear to be, can be used indiscriminately as a solvent or for edulcoration in chemical investigations. Solutions for testing are best prepared in test-tubes, or in small flaskss or beaker-glasses. Increase of the surfaces of contact by comminution, agitation, and increase of temperature, as is well known, aid and accelerate the process of solution, as well as of chemical reaction; and one or both of these auxiliaries may be employed, unless the nature of the substance or the effect of heat upon it is such as to exclude their application. Precipitation.-The formation of an insoluble body from a solution can be effected either by a change or modification of the solvent, or by the production of one or more new bodies, insoluble in the solvent. An instance of the first case is an 16 MANUAL OF CHEMICAL ANALYSIS. aqueous solution of barium chloride, which will be precipitated by the addition of concentrated hydrochloric acid, or a solution of calcium sulphate, which will be precipitated by alcohol; in both these instances the solvent power of the menstruum is lessened and solution may be reestablislied by the addition of a sufficient quantity of water. Instances of the second case of precipitation are a solution of calcium hydrate, precipitated by sodium carbonate, and a solution of magnesium sulphate. precipitated by barium hydrate. Precipitation is resorted to as the most important mode of detecting and discriminating bodies by their physical and chemical properties. The term " turbidity " designates the formation of a precipitate so insignificant in quantity, or so finely divided, or so light in weight, that the suspended particles only impair the transparency of the fluid, and require a certain amount of time to subside in the form of a precipitate. In the course of analytical investigation, each precipitation must be complete; to insurethis, the reagent must be added gradually, allowing the precipitate to subside after each addition, until no further precipitate is produced. In almost all cases separation of precipitates is aided by the application of gentle heat.;aS 111 The separation of the supernatant menstruum from a precipitate is effected either by filtration and subsequent washing of the precipitate upon the filter by means of a washing-bottle (Fig. 1), or, where the precipitate speedily and com((/:~"1 \\ pletely subsides, by decantation. As a rule, funnels and filters must be small, and proportionate to the amount of the __________ precipitate and the fienstruum; filters _llR!imAimmimiiwiir, should be cut so as not to project over FIG. I. the rim of the funnel, and it is also advisable to moisten the filter upon the funnel with distilled water, by means of the washing-bottle, previous to passing the fluid through it. Decantation is effected either by pouring off the supernatant clear part of OPERATIONS. 17 the fluid by simply inclining the vessel and allowing the fluid to flow down a glass rod (Fig. 2), or by drawing it off by means of a small glass siphon or a pipette (Fig. 3). FIG. 2. In either mode of separation the precipitate, in most instances, must be thoroughly freed from the menstruum by washing with water, either on the filter or by decantation. In all cases and operations of chemical examination, a reasonable economy with the sub- 0IlI stance and the solutions is advisable, so as to leave enough of the former for unseen contingencies and for confirmatory tests, as well as to repeat or verify any and all results of the examination. All tests and reactions are, therefore, performed on as 1IG. 8. small a scale as is reasonable and appropriate in the particular case; and all operations shoald proceed accordingly, and with constant observance of the princiDles and processes whereon they depend. 2 18 MANUAL OF CHEMICAL ANALYSIS. REA CGENTS. THE methods of chemical analysis and investigation consist in bringing the substances under examination into contact with other bodies of known properties, and observing the resulting phenomena. These phenomena consist in alterations, either in state of aggregation, form, or color, resulting from some chemical change. All bodies which are employed for this purpose are called reagents, and the ensuing phenomena reactions. It is obvious, therefore, that a sufficient knowledge of theoretical chemistry in its details, and especially a familiarity with the deportment, properties, and relations of the common compounds and reagents, are indispensable to the pursuit of chemical tests and examinations. Upon such knowledge depend the conception and comprehension of the conditions necessary for the formation of new compounds, and for the manifestation of the various reactions, as well as the correct inference from the observations and results of all investigations; and without it they will remain unavailing and uncertain. No special and definite rules can be assigned for the application of reagents in each instance, with respect to their proportion and quantity. These must depend upon the quantity and nature of the substance under examination and its solution, as well as upon the nature of the reagent, the strength of its solution, and the processes taking place in each particular reaction. Knowledge and reflection, as well as a ready comprehension of the object and aim of each test, of its issues, and of the possible incidents, and a correct inference from all phenomena, must decide at large, as well as in detail, not only what reagents should be employed, but also the amount and the conditions in each particular instance. A common error, and an obstacle to the less skilled, is the use of an excess of reagents. There are reagents which in many cases admit a free application without disadvantage to the correctness of the result-as, for instance, hydrosulphuric acid, solution of calcium hydrate, etc.; but the majority of reagents need to be applied in common tests only by a few drops of their solutions-as, for instance, baric, ferric, cupric, and argentic solutions, etc. On the other hand, there are not unfrequently REAGENTS. 19 errors arising from an insufficient amount in the application of reagents, especially with dilute solutions, or in those cases in which the complete elimination of a substance by precipitation is required for the subsequent examination for other bodies: for instance, hydrosulphuric acid, applied in a limited quantity, pro. duces a white precipitate with solutions of mercuric salts; applied in excess, it gives a black precipitate. There are other instances where an excess of the solution under consideration, as well as of the reagent, may redissolve, and consequently destroy, the precipitate whereon the reaction is based. In operations of chemical analysis it must always be borne in mind and well understood that, in the processes and phenomena taking place between the reagents and the substances acted upon, as in all chemical changes and reactions, certain laws and definite limits exist between cause and effect, and that the ability of correctly applying knowledge, judgment, and skill, and of drawing the right inference from necessary as well as from casual reactions and phenomena, must rule and guide the methods and operations of the investigator, and carry them beyond mere conjecture and empiricism. It is beyond the scope of this work to describe the mode of preparing the reagents, their use and application, and their deportment with the common compounds. For such information, reference must be had to the text-books of applied and analytical chemistry. From a practical point of view, only the usual strength of the solution of the reagents, as best suited for the common tests and examinations, and the mode of preparing a few of the rarer or special reagents, or of such as are not included among the medicinal chemicals considered in this volume, have been stated. It hardly needs to be mentioned that all reagents must consist purely of their essential constituents, and must contain nc admixture of any other substance; it must, therefore, be an invariable rule to test the purity of the reagents before they are employed. The reagents and their solutions must be preserved according to their nature; of those whose solutions are liable to altemation or decomposition, only small quantities must be kept, and always in tightly-closed glass-stoppered bottles. REA GENT S. Concentrated Sulphuric Acid.-Spec. grav., 1.843; containing about 78.36 per cent. anhydrous sulphuric acid. Strong Sulphuric Acid.-Spec. grav., 1.68; containing about 62.04 per cent. anhydrous sulphuric acid. Obtained by carefully mixing, in a flask or beaker, 1 part of water with 3 parts of concentrated sulphuric acid (Fig. 4). In diluting concentrated sulphuric acid with water, the acid should invariablv and gradually be added to the water, and in vessels which are either placed in cold water, or which are not liable to crack from the heat evolved. Diluted Sulphuric Acid. - Spec. grav., 1.113-1.117; containing about 13.50 per cent. of anhydrous sulphuric acid. Obtained by mixing 1 part of concentrated sulphuric acid FIG. 4. with 5 parts of water. Sulphurous Acid —An aqueous solution of sulphurous-acid gas, saturated at 15 C., containing about 37 times its volume of gas. Concentrated Hydrochloric Acid.-Spec. grav., 1.16; containing about 32 per cent. of anhydrous acid. Diluted Hydrochloric Acid. — Spec. grav., 1.038; contain REAGENTS. 21 ing about 8 per cent. of anhydrous acid. Obtained by mixing 4 parts of water with 1 part of concentrated hydrochloric acid. Concentrated Nitric Acid.-Spec. grav., 1.42; containing 60 per cent. of anhydrous acid. When concentrated acids are applied in small tests only by the drop, as, for instance, in testing alkaloids, etc., they are taken from the bottle by dipping a glass rod into the acid and allowing the drop or drops to fall upon the substance to be acted upon, or better by means of a kind of pipette consisting of a thin, strong | glass tube, adjusted at one end to a small caoutchouc bulb, and contracted at the other extremity to B a capillary end. The fluid is drawn into the tube, and delivered again by gentle pressure of the bulb FIG. 5 (Fig. 5). Diluted Nitric Acid.-Spec. grav., 1.068; containing 10 per cent. of anhydrous acid. Obtained by mixing 4 parts of water with 1 part of concentrated nitric acid. Oxalic Acid.-Solution of 1 part of crystallized oxalic acid in 12 parts of water. Acetic Acid.-Spec. grav., 1.047. Diluted Acetic Acid.-Obtained by mixing 4 parts of water with 1 part of acetic acid. Tartaric Acid.-Solution of 1 part of crystallized tartaric acid in 5 parts of water. Tannic Acid.-Solution of 1 part of tannic acid in a mixture consisting of 8 parts of water and 2 parts of alcohol. Indigo-Sulphuric Acid.-Solution of indigo in sulphuric acid. Five grains of finely-powdered indigo are digested in 2 drachms of concentrated sulphuric acid, in a corked test-tube, for 2 hours; subsequently, 4 ounces of strong sulphuric acid are added, and, after subsiding, the clear liquid is decanted, and carefully added to 2 ounces of water. 22 MANUAL OF CHEMICAL ANALYSIS. Indigo Sulphate.-Solution of 1 part commercial indigo carmine in 15 parts of water. Aniline Sulphate. Solution of a drops of aniline in 1 ounce of diluted sulphuric acid. Sulphuric-Acid Mucilage of Starch.-Half a drachm of starch, mixed with 1 ounce of cold water, is stirred into 3 ounces of boiling water; then half a drachm of diluted sulphuric acid, and, when cool, 5 drops of benzol are added. Mucilage of Starch.-20 grains of starch, mixed with 1 ounce of cold water, are stirred into 3 ounces of boiling water, and the boiling is continued for a few minutes; when cool, the clear liquid is allowed to stand for 12 hours, is then decanted, and a few drops of benzol are added; or it is saturated with sodium chloride, when it may be kept a long time without decomposition. Hydrosulphuric-Acid Gas (Sulphuretted Hlydrogen).-Obtained by the action of diluted sulphuric acid upon ferrous sulphide. Among the several convenient forms of apparatus for the continuous preparation of the gas and to keep it ready for use, the one represented in Fig. o ~e 6 is preferable. It consists of _ three glass bulbs, the two lower ones being a single piece, and the upper one, prolonged by a - tube reaching to the bottom of FIG. 6. the lower, being ground airtight into the neck of the second. Through the tubulure of the middle bulb the ferrous sulphide is inftroduced, and the tubulure then closed by a cork containing a wide glass tube * Obtained by precipitation of a diluted solution of indigo in Nordhausen oil of vitriol by a concentrated solution of pure potassium carbonate in excess; the deepblue precipitate is collected upon a filter, washed with some water until the filtrate'ceases to effervesce with concentrated acids, and is then dried. The obtained sulphindigotic potassium is soluble, with a deep-blue color, in 140 parts of water. REAGENTS. 23 provided with a stop-cock, or with a rubber tube, closed by a Mohr's wire clamp (see p. 56). The acid is poured in through the safety-tube, runs into the bottom globe, and rises to overflow the ferrous sulphide in the middle one. When the air has been allowed to escape through the delivery-tube, and this is closed, the pressure of the accumulating hydrogen sulphide forces the liquid from the second bulb down into the lower, and thence into the upper bulb, thus stopping the action, and preserving a volume of the gas ready for use. When no such apparatus is at hand, hydrosulphuric-acid gas may be generated, in small FIG. 7. tests, from a little flask or a test-tube (Fig. 7), taking care that none of the contents of the flask pass through the delivery-tube into the liquid under examination. Hydrosulphuric Acid.-A solution of hydrosulphuric- acid gas (sulphuretted hydrogen) in water, saturated at 15~ C., or FIG. 8. at a lower temperature, containing about four times its volume of the gas. The gas is likewise obtained by the action of diluted sulphuric acid upon ferrous sulphide, and is washed in water, contained in a small flask or cylinder (Fig. 8), before passing it into water for absorption. 24 MANUAL OF CHEMICAL ANALYSIS. In order to preserve the hydrosulphuric acid, it is advisable to fill the freshly-prepared saturated solution immediately into 2- or 4-ounce vials, and to place them, tightly corked, in an inverted position, in a jar filled with water. When, in the course of a test, a solution has to be acted upon for some time by hydrosulphuric acid, a test-tube or flask may be employed, of such size as nearly to be filled by the liquid. It may then be tightly stoppered, allowing sufficient escape of air before corking, if it has to be warmed. Chlorine Water.-A saturated aqueous solution of chlorine, containing about 0.4 per cent. by weight of gas. For analytical use, this solution is best preserved in 1-ounce vials, tightly corked and sealed, in a cool place. Iodine Water.-Add 1 drop of tincture of iodine to 3 fluidounces of water. Potassium Hydrate.-Solution of 1 part of fused potassium hydrate in 3 parts of water, containing 25 per cent. of potassium hydrate. Liquor Potassae, U. S. P.-Containing 5.8 per cent. of potassium hydrate. Potassium Carbonate.-Solution of 1 part of pure potassiun carbonate in 3 parts of water. Potassium Bicarbonate.-Solution of 1 part of potassium bicarbonate in 10 parts of water. Potassium Acetate.-Solntion of 1 part of potassium acetate in 5 parts of water. Potassium Iodate.-Fourteen grains each of iodine and of potassium chlorate are moistened with a little water, and triturated to a fine powder; a little more water, acidulated with 5 drops of concentrated nitric acid, is then added, and the whole digested in a flask at a gentle heat, until discolored; the heat is then increased to boiling, and the contents are subsequently transferred to a porcelain capsule, and evaporated to complete dryness at 1000 C. The residue is dissolved in 5 ounces of water, and filtered. Potassium Permanganate.-Solution of 1 grain of potassium permanganate in 5 ounces of water. Potassium Bichromate.-Solution of 1 part of potassium biehromate in 10 parts of water. REAGENTS. 20 Potassium Antimoniate.-A cold-saturated, aqueous solution of potassium antimoniate. Potassium Cyanide. Potassium Ferrocyanide.-Solution of 1 part of potassium ferrocyanide in 12 parts of water. Potassium Ferri Cyanide.-Solution of 1 part of potassium ferri cyanide in 20 parts of water. Potassium Sulphocyanide.-Obtained by boiling, in a flask, for 15 minutes, 1 drachm of fused potassium cyanide and 1 drachm of sublimed and washed sulphur in 6 drachims of water; then the liquid is filtered, and so -much water added as to make the quantity 6 fluid drachins. Potassium Iodide.-Solution of 1 part of potassium iodide in 10 parts of water. Commercial potassium iodide generally contains traces of potassium iodate, and this should be eliminated by dissolving the salt in boiling alcohol, to saturation, filtering the hot solution, and, when cool, collecting and drying the separated salt. Iodinized Potassium Iodide. — Eight grains of potassiuln iodide and 2 grains of iodine, dissolved in 2 ounces of water. Potassium Mercuric Iodide.-A solution of 11 grains of imercuric iodide and 8 grains of potassium iodide in 10 dracllms of water. Potassium Mercuric Iodide with Potassium Hydrate (Nessler's test). —A solution obtained by gradually adding mercuric iodide, mixed in a test-tube with some water, to a warm solution of 20 grains of potassium iodide in 1 drachm of water, until the mercuric iodide ceases to be dissolved (about 20 grains will be required); when cooled, 1 drachm of water is added, and, after allowing the solution to stand for 24 hours, it is filtered, the filter washed with a few drops of water, and 5 drachmns of Liquor Potassii, U. S. P., added. Sodium Hydrate (Liquor Sodii, U. S. P.).-Spec. grav., 1.071; containing 5.7 per cent. of sodium hydrate. Sodium Carbonate.-Dehydrated by exsiccation. Sodium Carbonate.-Solution of 1 part of crystallized sodium carbonate in 10 parts of water. Sodium Bicarbonate.-Saturated aqueous solution of sodium bicarbonate. 26 MANUAL OF CHEMICAL ANALYSIS. Sodium Bitartrate.-Saturated aqueous solution of sodium bitartrate. Sodium Acetate.-Solution of 1 part of crystallized sodium acetate in 5 parts of water. Sodium Phosphate.-Solution of 1 part of crystallized sodium phosphate in 5 parts of water. Sodium Hyposulphite.-Solution of 1 part of crystallized sodium hyposuiphite in 10 parts of water. Ammonium Hydrate (Aqua Ammoniae fortior).-A nearly saturated aqueous solution of ammonium hydrate. Spec. grav., 0.900; containing about 26 per cent. of the gas by weight. Aqua Ammoniae, U. S. P.-Spec. grav., 0.960; containing 10 per cent. of arnmonium hydrate. Ammonium Sulphydrate.-A solution of ammonium sulphydrate in water containing some ammonium hydrate; it is obtained by saturating, at 15~ C. or a lower temperature, 4 parts of Aqua Ammonite fortior, U. S. P., with hydrosulphuric acid gas, and by subsequent addition of 1 part of aqua ammonioe. It is best preserved in 1-ounce vials, tightly corked, and in a cool place. This solution, being concentrated, has to be employed, in the common test, only in small quantities, mostly by drops. When hydrosulphuric acid gas is at hand, ammonium sulphydrate may, in many of its applications, be produced by saturating the liquid under examination with the gas, and by subsequent addition of ammonium hydrate; or, in ammoniated solutions, if dilution does not interfere with the reaction, by addition of hydrosulphuric acid. Ammonium Carbonate.-Solution of 1 part of crystallized ammoniumn sesqui carbonate in 8 parts of water and 2 parts of. aqua ammonime. Ammonium Chloride. —Solution of 1 part of crystallized ammonium chloride in 10 parts of water. Ammoniated Magaesium Sulphate.-Solution of 2 parts of magnesium sulphate, 1 part of ammonium chloride, and 1 part of aqua armmonise, in 8 parts of water. Ammonium Oxalate.-Solution of 1 part of crystallized ammonium oxalate in 20 parts of water. Calcium Hydrate (Lime-water).-Saturated aqueous solution of calcium hydrate. REAGENTS. 27 Calcium Chloride.-1 part of precipitated calcium carbonate is shaken with 8 parts of water, and so much concentrated hydrochloric acid added as nearly to dissolve the carbonate; the solution is then filtered, and 2 parts of water are added. Calcium Sulphate.-Saturated aqueous solution of calcium sulphate, containing about 0.2 per cent. of the salt. Barium Hydrate. —Saturated aqueous solution of barium hydrate, containing about 5 per cent. of the salt. Barium Nitrate.-Solution of I part of crystallized barium nitrate in 16 parts of water. Barium Chloride.-Solution of 1 part of crystallized barium chloride in 16 parts of water. Nlagnesium Sulphate.-Solution of 1 part of crystallized magnesium sulphate in 10 parts of water. Ferrous Sulphate.-Solution of 1 part of ferrous sulphate, obtained by precipitation with alcohol, in 4 parts of water. Ferrous sulphate is best obtained by pouring an aqueous solution of freshly-prepared crystallized ferrous sulphate, saturated at the boiling-point, into strong alcohol, collecting the precipitate upon a filter, washing with a little alcohol, drying by pressing between filtering-paper, and by immediately filling the humid salt into small warm vials, which are corked and sealed while warm. The absence of ferric sulphate may be ascertained by testing the solution with potassium ferro-cyanide. No blue turbidity, or only a very slight one, should occur. Ferric Sulphate, obtained by diluting 1 part of Liquor Ferri Persulphatis, U. S. P., with 3 parts of water. Ferric Chloride, obtained by diluting 1 part of Liquor Ferri Perchloridi, U. S. P., with 3 parts of water. Ferri dinitrosulphide, obtained by adding, drop by drop, a solution of ferric chloride or sulphate, with constant stirring, to a mixture consisting of equal parts of strong solutions of potassium nitrate and ammonium sulphydrate, heating the liquid to boiling for a few minutes, and filtering while hot from the sulphur. The deep-colored liquid deposits, on cooling, black, needle-shaped rhombic prisms of ferri dinitrosulphide; these are dissolved 1 part in 10 parts of water, to give the required solution. Cobaltous Nitrate.-Solution of 1 part of cobaltous nitrate in 10 parts of water. 28 MANUAL OF CHEMICAL ANALYSIS. Stannous Chloride.-Saturated solution of real and pure tinfoil in concentrated hydrochloric acid, with subsequent addition of a little concentrated hydrochloric acid. Plumbic Acetate.-Solution of 1 part of crystallized plumbic acetate in 10 parts of water. Plumbic Nitrate. —Solution of 1 part of crystallized plumbic nitrate in 10 parts of water. Cupric Sulphate.-Solutioh of 1 part of crystallized cupric sulphate in 10 parts of water. Fehling's Solution. —4 drachms (17.33 grammes) of pure crystallized cupric sulphate are dissolved in 2 ounces of water; 21 ounces and 2 scruples (86.25 grammres) of pure crystallized potassium and sodium tartrate are dissolved in 5 ounces of water, and 2- ounces (70 grammes) of Liquor Sodoe of 1.3 spec. grav. are added. Then the cupric solution is gradually added to the latter one, and the liquid passed through a filter, and so much water added as to make the whole measure 16 fluidounces (500 cubic centimetres). Mercuric Chloride. —Solution of 1 part of crystallized mercuric chloride in 20 parts of water. Argentic Nitrate.-Solution of 1 part of crystallized argentic nitrate in 20 parts of water. Platinic Chloride.-Solution of 1 part of platinic chloride in 20 parts of water. Nascent Hydrogen is a very delicate means of detecting arsenic; this test depends upon the production of hydrogen arsenide, whenever arsenic is present in any soluble form, in a solution in which hydrogen is being evolved by the action of zinc upon hydrochloric or sulphuric acid. There are two methods of the application of this test; the one long known as Marsh's test, and preeminently adapted for forensic and quantitative detection and estimation of arsenic, the other of recent device, and preferable-for the ready and prompt qualitative detection of arsenic. A complete but simple form of apparatus for Ararsh's test is represented in Fig. 9; it consists of a generating-flask a, of about 4 to 6 ounces' capacity, provided by means of a twice-perforated cork, or rubber stopper, with a funnel-tube and a delivery-tube, which last is connected by rubber corks with a wider glass tube, REAGENTS. 29 c, loosely filled with fragments of calcium-chloride; to the opposite end of this drying-tube is attached a long piece of narrow tubing of hard German glass, d, drawn out into a capillary end. and bent up so as to form a vertical jet. FIG. 9. The test consists in introducing into the flask a pure granular zinc or magnesium, and a little water; when the apparatus is tightly fitted, hydrochloric or sulphuric acid is added through the funnel-tube. It is necessary in each case first to ascertain the purity of these substances. After the evolution of gas has continued long enough to expel the atmospheric air, the reduction-tube, d, is heated to redness for about ten minutes, the escaping gas is lighted, and a piece of white porcelain held in the flame. If no dark deposit takes place, either in the tube or on the porcelain, the liquid to be tested may then be added through the funnel-tube, and the operation continued in the manner described. If arsenic-spots are obtained in the tube, a number of them may be produced by heating the tube in at least two places, at distances of about three inches, or if an approximately quantita 30 MANUAL OF CHEMICAL ANALYSIS. tive estimation of the arsenic is desired, all the arsenic may be obtained by the employment of a longer reduction-tube and several flames. The obtained arsenic mirrors may be examined for identification or quantitatively determined by subsequently cutting off the tube with a file. flager's test, requiring a simpler apparatus and less time, depends upon the action of hydrogen arsenide upon soluble argentic salts, forming black argentic arsenide, and consists in evolving hydrogen in a long test-tube, and allowing the escaping gas to pass through a cover of white bibulous paper moistened with solution of argentic nitrate, or closing the tube loosely with a cork, into the lower end of which a strip of stiff white blotting-paper paper, moistened with the argentic nitric solution, has been fastened. Since, however, the presence of the lower oxy-acids of sulphur and selenium give rise to the formation of hydrosulphuric acid, which also blackens argentic salts, this test has invariably to be preceded by a test for the absence of such acids, for which purpose plumbic acetate is employed, which is not decomposed by hydrogen arsenide. A mixture of 1 part of concentrated hydrochloric acid with 2 parts of water, or, when sulphuric acid is employed, a mixture of 1 part of concentrated sulphuric acid with 4 to 5 parts of water, is introduced into a long test-tube (Fig. 10), taking care that it fills only about one-tenth of the capacity of the tube, and that the upper parts of the interior of the tube remain dry; a few pieces of pure zinc are then placed in the acid, and a small bunch of cotton, moistened with a solution of plumbic acetate, is inserted into the orifice of the tube, which is then allowed to stand for half an hour; if, after that time, the cotton remains colorless, the reagents are free from lower oxy-acids of sulphur and selenium, which are liable to form hydrosulphuric acid, and to impair the correctness of the test. The operation may then be repeated with the addition of the liquid to be tested, and with the precaution to ascertain, notwithstanding the purity of the reagents, the absence of hydrosulphuric acid, by the simultaneous exposure of argentic nitrate and plulnbic acetate to the escaping gas; this is done REAGENTS. 31 by employing the cotton moistened with solution of plumbic acetate and pressing it a little into the tube; the opening is then loosely tied with white blotting-paper, and this moistened with one drop of solution of argentic nitrate; or a few fragments of cork are placed upon the cotton, and a little gunFIG. 10. cotton moistened with solution of argentic nitrate is placed above. Instead of cotton and paper cover, a cork may be em. p]oyed, provided with two small strips of stiff; white blottingpaper, which are moistened immediately before the operation is instituted, the one with solution of argentic nitrate, the 32 MANUAL OF CHEMICAL ANALYSIS. other with solution of plumbic acetate; the cork is then loosely fitted into the test-tube, and this allowed to stand for half an hour. If arsenic be present, the paper cover, or strip, or the guncotton, containing the argentic solution, will become black; the strip moistened with plumbic acetate must remain white. As an additional evidence that the'brown or black reaction is argentic arsenide, the paper or cotton containing the dark reaction may be immersed in an aqueous solution of potassiumn cyanide (1 to 8) in a test-tube, and this gently warmed, by dipping it in water of 50~ C.; the dark spots of argentic arsenide will become a little lighter, but will not disappear, while spots of argentic sulphide disappear at once, and spots of argentic phosphide or antimonide are dissolved gradually. Ether.-Spec. grav., 0.728. Absolute Alcohol.-Spec. grav., 0.793. Chloroform.-Spec. grav., 1.480. Carbon Bisulphide.-Spec. grav., 1.272. Benzol. —Spec. grav., 0.680 to 0.700. Albumen.-The white of one chicken-egg is agitated with 3 ounces of water, and is then filtered through clean tow, previously moistened with water. Gelatin.-Solution of 10 grains of ichthyocolla, in shreds, in each ounce of water, obtained by digestion and subsequent filtration through moistened clean tow. Neutral Litmus-Solution is prepared by digesting, for 24 hours, 1 part of powdered commercial litmus in about 10 parts of water; the solution is then filtered, and the filter washed with 4 parts of water. The filtrate obtained is divided into two equal parts; to one of them very dilute phosphoric acid is added, drop by drop, with constant stirring, until the liquid turns faintly red. The red liquid is then -added to the blue portion, 2 parts of alcohol are added, and the whole kept in small, well-corked bottles. Blue Litmus-Paper is prepared by drawing unsized white paper (Swedish filtering-paper) through the above neutral liquid. Red Litmus-Paper is prepared by drawing unsized white REAGENTS. 33 paper (Swedish filtering-paper) through the acidulated reddened part of the litmnus-solution, as obtained and described above, in the preparation of neutral litmus-solution. The paper obtained is dried in warm air, and, for ready use, is cut into strips of about - of an inch wide and 4 inches long, and preserved enclosed in paraffin-paper, or in tightlycorked bottles. In reactions of neutralization, where carbonic-acid gas is evolved, this substance acts on litmus, and may impair the correctness of the test; in such operations it is therefore better, if admissible, to operate on warm solutions, in order quickly to expel the carbonic-acid gas; if heat be incompatible, turmericpaper may be used instead of litmus-paper. Turmeric-Solution, obtained by digestion of 1 part of powdered rhizomas of turmeric in a mixture of 4 parts of alcohol and 3 parts of water. After one or two days, the liquid is filtered off and preserved. Turmeric-Paper is prepared from this tincture by steeping in it white unsized paper (Swedish filtering-paper). The paper need not be preserved from the action of the atmosphere, since it remains unchanged by carbonic acid. Alkanet-Paper is prepared like litmus-paper, by saturating unsized paper with a solution of the alkanet-red. This is obtained by extracting dry alkanet-root with ether; the filtered solution is ready for use. The blue paper may be obtained from the red one by dipping it into an aqueous solution of sodium carbonate (1.500). A neutral paper, answering for the alkaline as well as the acid test, may be prepared by dividing the ethereal solution of alkanet-red into two equal parts; to one is added, drop by drop, an aqueous solution of sodium carbonate, until the red is just changed to a distinct blue tint; then both liquids are mixed and used for the preparation of the paper. 3 BR I E F COURSE OF QUALITATIVE CHEMICAL ANALYSIS. CHEMICAL tests and examinations must be founded upon a thorough knowledge of the nature and relations of the reagents, and of their deportment with the common compounds, and also upon a certain fixed order and methodical system in their application. These attainments, and the necessary skill, experience, and judgment, are requisite for every one who enters upon testing and investigation with a chance or claim of accuracy or certainty. The following brief outline of a simple progressive course of qualitative chemical analysis depends, first, upon the successive elimination of groups of elementary compounds which possess certain common chemical properties, and, finally, upon the recognition of each member of such groups; it mnay therefore serve as a guide whenever, in the course of investigation, recourse is to be had to such a systematic method of analysis. For obvious reasons, only those elementary bodies and their compounds have been taken into consideration which are met with in the examination of medicinal chemicals and their preparations. For any more comprehensive or elaborate information, the standard works of analytical chemistry should be consulted. -When the object of the examination is only to establish the presence or absence of some particular substance, the charac QUALITATIVE CHEMICAL ANALYSIS. 35 teristic reagent may be employed at once; but, if a qualitative analysis is required, the substance, if a solid body, may be subjected first to a preliminary examination in the dry way, by which means approximate information as to its composition may be obtained; after this, it is dissolved, and examined. The course of qualitative analysis, therefore, consists of three parts: I. Preliminary examination in the dry way. II. Solution, or conversion into the liquid form. III. Analysis of the solution. I. PRELIMINARY EXAMINATION. This consists in an accurate observation of the physical properties of the substance, its form, color, hardness, gravity, and odor, and of its deportment at a high temperature, either alone, or in contact with some chemical compound which produces decomposition. 1. THE SUBSTANCE IS HEATED IN A DRY NARROW TUBE (Fig. 11). (a) Organic compounds carbonize and blacken, evolving empyreumatic, inflammable gases. (b) The substance remains unaltered; indicating absence of organic matter, of salts containing water of crystallization, and of volatile compounds. (c) The substance fuses, expelling aqueous vapors, which condense in the cooler parts of the tube; indicating salts with water of crystallization (these will generally re-solidify after the expulsion of the water), or decomposable hydrates, which often give off their water without fusing. (d) Gases or fjumes are evolved: smell of iodine from iodine compounds; smell of sulphurous acid from decomposition of sulphates; smell of nitric oxides from the nitrates; smell of ammonia from ammonium salts, from cyanides, or from nitrogenous organic compounds, in which latter case carbonization takes place, and either cyanogen or empyreumatic fumes escape with the ammonia. (e) Sublimates are formed by volatile substances, as sulphur, 36 MANUAL OF CHEMICAL ANALYSIS. and compounds of ammonium, mercury, arsenic, and antimony. In this case the sublimate is removed to the bottom of the test-tube, and, together with the substance, is covered with a Fta. 11. few small pieces of charcoal, and again heated; mercury and arsenic form metallic sublimates, the latter with the characterFIG. 12. istic garlic odor, the former without. In another tube part of the substance is heated, and the sublimate is moistened with solution of potassium hydrate; mercurous chloride turns QUALITATIVE CHEMICAL ANALYSIS. 37 black; mercuric chloride, red; and ammonium salts evolve the odor of ammonia. 2. THE SUBSTANCE IS MIXED WITH DRIED SODIUM CARBONATE, AND HEATED ON CHARCOAL IN THE REDUCING FLAME OF THE BLOW-PIPE (Fig. 12). (a) Fusion and absorption into the coal indicate alkalies. (b) An irifusible white residue, either at once or after previous fusion in the water of crystallization, indicates compounds of calcium, barium, strontium, magnesium, aluminium, zinc, or tin. (c) A reduction to the metallic state takes place, without formation of a peripheric incrustation upon the charcoal. Compounds of tin, silver, and copper, give malleable shining scales. Compounds of iron, manganese, cobalt, and nickel, are reduced to a gray infusible powder; all visible upon cutting the fuse from the coal, and triturating and levigating it in an agate mortar. (d) Reduction with incrustation: Antimony compounds give a brittle metallic globule and a white incrustation; bismuth, a brittle globule and a brown-yellow incrustation; lead, a malleable globule and a yellow incrustation; zinc and cadmiumn are not reduced, but give, the former a white incrustation, not volatile in the oxidizing flame, the latter a brown-red incrustation. (e) Arsenic compounds give the smell of garlic. (f) Borates and aluminates swell up. (g) Sulphur compounds give an alkaline sulphide, which, when moistened, leaves a black stain upon a clean silver plate. II. SOLUTION OF SOLID BODIES. After having ascertained, by the preliminary examination, to what class of bodies the substance under consideration belongs, it has then to be brought into the liquid form-in other words, to be dissolved. The usual solvents which are employed are water, hydrochloric and nitric acids, and aqua regia. The finely-powdered substance is first boiled with from 12 to 20 times its weight of distilled water, in order to ascertain its complete or partial solubility, or its insolubility therein. If it 38 -MANUAL OF CHEMICAL ANALYSIS. be not completely dissolved, the portion insoluble in water is collected upon a filter, and is then treated successively with dilute and concentrated hydrochloric acid; by this process carbonates evolve carbonic-acid gas, with effervescence; peroxides, chromates, and chlorates, evolve chlorine; cyanides give hydrocyanic acid; many -sulphides, hydrosulphuric acid; sulphites and hyposulphites, sulphurons acid. If hydrochloric acid does not completely dissolve the substance, it generally effects the separation of one or more of its constituents; for this reason the solution should be separated from the residue and examined apart. The residue may consist of compounds undecomposable by hydrochloric acid, which existed in the original substance; or of insoluble compounds formed by the decomposition of the 6riginal substance by hydrochloric acid. Thus sulphur is separated from polysulphides, and pulverulent or gelatinous silica fromn silicates; or, if lead, silver, or subsalts of mercury be present, insoluble chlorides of these metals will be formed. In this latter case, argentic chloride may be distinguished by its solubility in aqua ammnoni, a and imercurous chloride by its reduction to black mercurous oxide. If the substance is not completely soluble in hydrochloric acid, the insoluble residue is treated successively with nitric acid and aqua regia, which either act as mere solvents or exert an oxidizing action. When a finely-powdered substance is not dissolved by successive treatment with either of these solvents. it must be rerndered soluble by other means, in order that its constituents may be determined. This is generally accomplished by fusion with 3 to 4 parts by weight of alkaline carbonates, in the case of the sulphates of barium, strontium, calcium, and lead, and also of silica and silicates, or by fusion with potassium bisulphate in the case of alumina or aluminates. III. QUALITATIVE ANALYSIS OF SOLUTIONS. 1. EXAMINATION FOR BASES. The most important groups of bodies are the simple compounds of the so-called metallic elements, which contain generally but one base and one acid, or one metallic and one QUALITATIVE CHEMICAL ANALYSIS. 39 non-metallic element. The elimination of the former depends upon the different solubility of their sulphides, and, upon this fact, they are divided into three groups, which afterward are successively discriminated; by this proceeding, the detection of each individual member of such group is considerably facilitated. Group I.-3fetals whose sulphides are insoluble in water or diluted acids. They are all precipitated from their acid solutions by hydrosulphuric acid. They are divided into two subdivisions: (A) Metals whose sulphides are sulpho-acids, forming with sulpho-bases (ammonium, potassium, and sodium sulphides) soluble sulpho-salts. These are: arsenic, antimony, tin, and gold. (B) Metals whose sulphides do not possess acid properties, not combining with, and therefore insoluble in, alkaline sulphides. These are: lead, silver, mercury, bismuth, copper, and cadmium. (Sulphide of mercury is soluble in potassium or sodium sulphide, and sulphide of copper is somewhat soluble in ammoniurn sulphydrate.) Group II. —2fetals whose sulphides form soluble sulphoscalts, which consequently are not precipitated by hydrosulphuric acid from neutral or acid solutions, but partly fiom alkaline solutions; which, however, are completely precipitated by ammonium sulphydrate from neutral as well as from alkaline solutions. These are, again, subdivided into two groups: (A) Metals which are precipitated as sulphides: iron, manganese, zinc, nickel, and cobalt. (B) Metals which are precipitated as oxy-hydrates: aluminium and chromium. Group III. —lfetals whose sulphides and hydrcates are soluble in water; and which, therefore, are not precipitated by hydrosullphuric acid nor by ammonium sulpllydrate from any solution. This group includes the so-called alkalTne and alkaline-earthy metals. They are subdivided according to their deportment with ammonium carbonate in the presence of ammonium chloride. (A) Metals which are precipitated by ammonium carbonate, their normal carbonates being insoluble in water or in ammonium chloride; these are: calcium, barium, and strontium. 40 MANUAL OF CHEMICAL ANALYSIS. (B) Metals which are not precipitated by ammonium carbonate; these are: magnesium, potassium, sodium, and ammonium. Mlagnesiurn carbonate is insoluble in water, but soluble in ammonium chloride; the carbonates of the alkaline metals are soluble in water. If a solution is supposed to contain several or all of these metals, it' is obvious that, by the successive application of these general reagents, we shall separate,jfirst, by hydrochloric acid, those metals whose chlorides are insoluble in water or in dilute acids; secondly, by hydrosulphuric acid, those metals whose sulphides are insoluble in diluted acids; thirdly, by ammonium sulphydrate, those remaining metals whose sulphides or hydrates are insoluble in neutral or alkaline liquids; and, finally, by ammonium carbonate, those metals whose carbonates are insoluble: so that at last only the alkaline metals are left in solution. Hereupon the following course and method of investigation may be employed, with the observation of the following rules: The precipitation by each general reagent must be complete. To insure this, the reagent must be added gradually, allowing the precipitate to subside between each addition, until no further precipitate is produced. In the case of hydrosulphuric acid, the precipitation is complete when the solution, after agitation, still smells strongly of the gas. Each group, when precipitated, must be thoroughly freed, by washing with water, from all members of the subsequent groups, which may be contained in the solution. After the precipitation of each group, it is advisable to ascertain the presence or absence of any members of the succeeding groups, by evaporating on platinum-foil a few drops of the filtrate; if, after ignition, there is no distinctly visible residue, non-volatile substances need not be looked for further. It is obvious that, if complete precipitation and thorough washingo be neglected, metals belonging to one group are liable to be found among those of another group; and, consequently, as the analysis pro. ceeds, reactions will be obtained which will be a source of perplexity and errors. QUALITATIVE CHEMICAL ANALYSIS. 41 To part of the solution of the substance under examination, acidulated with hydrochloric or nitric acid, add hydroseuphutic acid: Precipitate No. 1. Yellow precipitate: arsenic, tin, and cadmium. Orange precipitate: antimony. Brown precipitate: gold and subsalts of tin. Black precipitate: mercury, lead, bismuth, silver, and copper. Filter, preserve the filtrate, and mark it No. 1. Wash precipitate No. 1 on a filter, and treat with ammonium sulphydrate; filter, and preserve the residue, marked No. 1, on the filter. The filtered solution of sulphides is now over-saturated with hydrochloric acid: the ensuing precipitate may contain the sulphides of arsenic, antimony, tin, and gold; it is washed and treated with solution of ammonium carbonate, which dissolves arsenic; from this filtered solution the arsenic may be re-precipitated by hydrochloric acid, and may be identified as arsenic by the metallic mirror, and by the garlic-like odor when heated with charcoal in a glass tube. Those sulphides which are not soluble in ammoniurn carbonate are distinguished by their deportment when heated on charcoal in the blowpipe-flame; antimony oxidizes in the oxidizing part of the flame, giving white fumines and an incrustation of antimonic oxide; sulphide of tin, not being volatile, remains on the charcoal, and gives, when fused with potassium cyanide, malleable metallic globules of tin. An examination for gold is only required when the solution of' the original substance had a yellow color; in this case the solution is tested with ammonium chloride, and then heated with ferrous sulphate; gold is reduced and precipitated as a fine brown powder. Residue No. 1 is treated on its filter with warm nitric acid; sulphide of mercury remains undissolved; it is dissolved in aqua regia, and recognized by reduction with -stannous chloride. Part of the nitric-acid solution of the sulphides is tested with sulphuric acid for lead; if this be present, it must be completely precipitated from the solution before testing the same with hydrochloric acid for silver, and this metal, if pres 42 MANUAL OF CHEMICAL ANALYSIS. ent, must also be completely precipitated; the filtered solution is next over-saturated with ammonium hydrate; an ensuing blue color indicates copper, and a white precipitate, bismuth:; in the latter case the precipitate is collected upon a filter and dissolved in a few drops of strong nitric acid, which solution, when dropped into an excess of water, will give rise to the formation of white turbid clouds. Finally, the solution filtered from the bismuth is treated with ammonium carbonate; cadmium, if present, is precipitated, and may be confirmed by the formation of brown circular incrustations on the charcoal, when the precipitate is heated with exsiccated sodium carbonate in the reducing flame. Filtrate No. 1, when an examination upon fixed constituents, by evaporation and heating upon platinum-foil, has an affirmative result, is over-saturated with ammortnizm hydrate, and an excess of ammonium suXphydracte is added. Precipitate No. 2. Black precipitate: iron, cobalt, and nickel. Flesh-colored precipitate: manganese. Bluish-green precipitate: chromium. White precipitate: aluminium and zinc. Filter, preserve the filtrate, and mark it No. 2. Wash the precipitate on the filter, and dissolve in hydrochloric acid. Only the sulphides of nickel and cobalt remain undissolved; they are dissolved upon the filter with warm nitric acid; the ensuing solution is slightly over-saturated with ammonium hydrate, and subsequently treated with potassium hydrate: nickel is precipitated as green oxyhydrate; the solution filtered from the nickel is tested with hydrosulphuric acid; a black precipitate of cobalt sulphide is identified as such by fusing it before the blowpipe with a borax-bead, to which it imparts a blue color. The hydrochloric-acid solution of precipitate No. 2, containing the metals of the second group, is boiled, after the addition of concentrated nitric acid, until the evolution and odor of hydrosulphuric acid cease, when it is filtered and over-saturated with ammonium hydrate: the ensuing precipitate may contain QUALITATIVE CHEMICAL ANALYSIS. 43 the hydrates of iron, aluminium, and chromium. They aie collected upon a filter, and the filtrate is marked No. 3. In order to discriminate them, the precipitate is treated with a solution of potassium hydrate: aluminium and chromium oxides dissolve; the liquid is diluted with a little water, filteredl and heated to boiling; chromium hydrate is re-precipitated, the solution is then filtered, and boiled with ammoniumr chloride: aluminiume hydrate is precipitated. The residue from the precipitate remaining undissolved in potassium hydrate is dissolved in a little hydrochloric acid, and recognized as iron by precipitation with potassium ferrocyanide. -Filtrate No. 3 is boiled with potassium hydrate: an ensuing precipitate, first white, and gradually turning brown, indicates manganese, which may also be recognized by the green fuse, when a part of this precipitate is fused with a mixture of sodium carbonate and potassium nitrate on platinum-foil. The solution, filtered from the precipitate, gives, on the addition of hydrosulphuric acid, a white precipitate of zinc sulphide, if that metal be present. _iltrcate 2o. 2, when evaporation upon platinum-foil indicates fixed constituents, is over-saturated with hydrochloric acid, and is heated until the odor of hydrosulphuric acid nearly or entirely ceases; when cold, it is filtered, slightly over-saturated with ammonium hydrate, and completely precipitatecd by ammonium carbonate. The carbonates of calcium, barium, and strontium, are thrown down. The precipitate is dissolved in hydrochloric acid, and the resulting solution is tested by agitation with a saturated solution of calcium sulphate: if a white precipitate be formed immediately, tlhe presence of barium is shown; if it be formed after a while, strontium is indicated. If both these alkaline earth-metals be present, the solution is completely precipitated by sulphuric acid; the filtered solution is then neutralized with ammonium hydrate, and tested with ammonium oxalate; an ensuing white precipitate indicates calcium. If the solution filtered from the earthy carbonates shows fixed constituents upon evaporation on platinum-fobil, part of it is examined with sodium phosphate: all ensuing white precipitate of magnesium and ammonium phosphate indicates 44 MANUAL OF CHEMICAL ANALYSIS. magnesium. If this metal be present, the solution is exactly neutralized with hydrochloric acid, and is then agitated with barium hydrate, so that the magnesium may be completely precipitated as hydrate; the excess of barium is completely removed from the filtrate by sulphuric acid; the filtrate is then evaporated to dryness, the residue moistened with hydrochloric acid, and heated to redness; it is then examined upon platinum-wire in an alcohol-flame; sodium imparts a yellow, potassium a red, color to the flame; for verification, the rest of the residue may be dissolved in a few drops of water, and tested with platinum chloride; a yellow crystalline precipitate of potassium platinic chloride will be formed, if potassium be present. Amnmonium is always sought for in a separate portion of the original substance or solution, by heating with a concentrated solution of potassium or sodium hydrate: any ammonium compound evolves the characteristic odor of ammonia. II. EXAMINATION FOR ACIDS. The examination for the bases is followed by that for the acids and for chlorine, iodine, and bromine. The preliminary examination, as well as the nature of the substance and the bases found therein, will give information, in most cases, as to what acids cannot be contained in the substance, and what acids may be present therein or should especially be looked for. Thus the acids of arsenic, and chromic, carbonic, and hydrosulphuric acids, have already been indicated. With soluble substances containing earthy and metallic bases, the presence of carbonic, phosphoric, boric, and oxalic acids, is excluded; soluble substances, containing silver, lead, and mercurous compounds, exclude chlorine; soluble substances, containing lead, barium, strontium, and imercurous salts, exclude sulphuric acid. In the examination for acids, a neutral solution is frequently required, and generally ammoniumn hydrate is used for neutralization; but, as most of the heavy metals, as well as some alkaline earthy salts, are precipitated when their solutions are neutralized by ammonium hydrate, it is often necessary to QUALITATIVE CHEMICAL ANALYSIS. 45 remove from the solution all metals, except those of the alkalies, before proceeding to search for acids. When this is not necessary, it is frequently requisite, according to the nature of the substance and its chemical relations, to substitute, instead of hydrochloric acid and its salts, nitric acid and the corresponding nitrates. The general reagents employed in the examination for acids are barium chloride or nitrate, calcium chloride, argentic nitrate, ammonium and magnesium sulphate, ferric chloride, and indigo-solution. By these reagents the common acids are divided into certain groups: 1. Acids which are precipitated by barium nitrate:-a,from acidulated solutions: sulphuric acid; —b, from neutral solutions (the precipitate being soluble in acids): sulphurous, phosphorous, carbonic, silicic, oxalic, chromic, boric, tartaric, citric, and arsenic acids. 2. Acids which are precipitated by calciumr chloride:-a, from neutral solutions only: phosphoric, arsenic, boric, carbonic, sulphurous, tartaric, citric acids, and ferrocyanides;- b, from neutral or acetic-acid solutions: sulphuric and oxalic acids. 3. Acids which are precipitated by magnesium sulphate, in presence of ammonium hydrate and ammonium chloride: phosphoric, arsenic, and tartaric acids. 4. Acids which are recognized by ferric chloride:-a, are precipitated: ferrocyanides, phosphoric, arsenic, tannic acids (from a neutral or acetic-acid solution), boric, benzoic, and succinic acids (from neutral solutions only);-b, those w]hich give only a colored reaction (in acid solutions): ferricyanides (brown); —in neutral solutions only: acetic acid, sulphurous acid (red), and gallic acid (black). 5. Acids which are precipitated by argentic nitrate:-a, from neutral solutions (precipitate being soluble in dilute nitric acid): phosphoric, pyro- and metaphosphoric, arsenious, arsenic, chromic, oxalic, boric, tartaric, citric, sulphurous, and formic acids;-b, from acid solutions also (the precipitate being insoluble in dilute nitric acid): hydrochloric, hydrobromic. hydroiodic, hydrocyanic, iodic, hydrosulphuric acids, and ferro- and ferricyanides. 46 MANUAL OF CHEMICAL ANALYSIS. 6. Acids which decolorize indigo solution: free chlorine and bromine, and their oxygen acids, when free; free nitric acid, if not too dilute, and alkaline sulphides. On the addition of sulphuric or hydrochloric acids, and heating, indigo-solution is also discolored, by all chlorates, bromates, iodates, and nitrates, and, on addition of Ihydrochloric acid and heating, besides all the foregoing acids, also by chromates, permanganates, and all peroxides. Hereupon the following mode of investigation for the most common acids is based: Add to a part of the solution barium chloride, or, if silver, lead, or mercurous salts are present, barium nitrate; an ensuing precipitate, insoluble on the addition of hydrochloric or nitric acid, indicates sulphuric acid; if the precipitate be partly or entirely dissolved, the acids of arsenic, or phosphoric, boric, chronic, oxalic, or tartaric acid, may be present: in this case part of the original solution is over-saturated with amlmonium hydrate, and is tested with ammoniated magnesium sulphate, and warmed; the occurrence of a white crystalline precipitate indicates phosphoric or arsenic acid; the latter one has already been indicated in the preliminary examination, and its presence may be confirmed, by fusing part of the original substance, or the residue of the evaporated solution, on charcoal with potassium cyanide. If arsenic acid is found to be present in the solution, it has to be removed by reduction with sulphurous acid and by subsequent precipitation with hydrosulphuric acid. Then phosphoric acid may be recognized in the filtrate by the addition of ammoniated magnesium sulphate, and by redissolving the resulting precipitate in nitric acid and re-precipitation by argentic nitrate, which, when phosphoric acid is present, will give a yellow precipitate.:Boric acid is detected in the substance by its property of imparting a green color to the alcohol-flame, and by its reaction with turmeric-paper. When the solution of the original substance was yellow or red, and the precipitate with barium was also yellow, chromic acid may be present; in this case, the chromic acid has to be reduced to chromium oxide by alcohol QUALITATIVE CHEMICAL ANALYSIS. 47 and hydrochloric acid, and may then be recognized, as stated in the examination for bases (page 43). Tartaric and citric acids have'been already indicated in the preliminary examination. Oxalic acid is detected in neutral solutions by calcium sulphate, the white calcium oxalate being insoluble in acetic acid. Part of the solution, prepared or acidulated with nitrie acid, is precipitated with argentic nitrate; an ensuing precipitate, insoluble in nitric acid, would indicate hydrochloric or hydrocyanic acids, iodine, bromine, and ferro- and ferricyanFIG. 13. ides. Hydrocyanic acid, besides being already indicated in the preliminary examination, may be detected by its reaction with ferrous and ferric salts. If the silver precipitate be yellowish, and insoluble in ammonium hydrate, it indicates iodine: in this case the original substance, on being heated in strong sulphuric acid, emits the vapor and odor of iodine. If the precipitate be curdy, and soluble in ammonium hydrate, it indicates, if no cyanogen compounds be present, hydrochloric acid: if this be the case, the cyanogen has to be destroyed by fising the substance with a mixture of sodium carbonate and nitrate; the residue is extracted with water, and the 48:MANUAL OF CHEMICAL ANALYSIS. filtered solution, acidulated with nitric acid, is then tested with argentic nitrate. Nitric and chloric acids have already been detected in the course of the preliminary examination. The former may also be recognized by mixing the solution in a test-tube with an equal bulk of concentrated solution of ferrous sulphate, and pouring the mixture carefully upon concentrated sulphuric acid, so that the fluids do not mix (Fig. 13).. If nitric acid be present, the line of contact between the two fluids will show a dark redbrown coloration. Chloric acid will be detected by the evolution of chlorine, when the original substance is warmed in strong sulphuric acid. This brief outline of a systematic course of analysis is necessarily open to modification in its details; such will be designated in many cases by the results of the preliminary examination. As has already been stated, the search for the acids is especially more or less dependent upon the results of the previous examination, and the substances found. Complex substances, and those which resist the common solvents, have to be dealt with by special processes in order to transform their constituents into soluble compounds, as stated on page 38, or by methods better adapted to their nature. Thus, insoluble compounds of the heavy metals may be decomposed by digestion with amnmonium sulphydrate; sulpllates of strontium and calcium, by digestion with sodium carbonate; in both cases, the filtrate contains the acid, together with an excess of the decomposing agent, while the metal is found in the residue. Insoluble salts of organic acids are decomposed by boiling with an alkaline carbonate: iron salts containing volatile organic acids, by digestion with ammonium hydrate; in both cases, the filtrate contains an alkaline salt of the acid. Sulphides, and all the lower oxygen acids of-sulphur, yield sulphuric acid when digested with nitric acid, or any corresponding oxidizing agent. QUALITATIVE CHEMICAL ANALYSIS. 49 TAB LE OF THE DEPORTMENT OF THE COMPOUNDS OF THE COMMON METALS WITH SOME OF THE GENERAL REAGENTS. Oxides precipitated by HYDROSULPHURIC ACID from Acid Solutions: Alkaline Solutions: a8 Sulphides: as Sulphides: as Oyhydratm: As Sb Sn Au Pt Hg Bi Fe Mn Co Ni Zn. Al1 r. Ag Cu Pb Cd. Sulphides soluble in Nitric Acid: Aqua Regia: Ammonmium Suiphydrate: PbS BiS CuS AgS HgS CoS NiS. AsS SbS SnS CdS FeS MnS ZnS. AuS PtS. Oxides precipitated by Hydrochloric Acid: Sulphuric Acid: Ammonvium Hydrate: Pb Ag Pb Hg2O Fe Co Ni Mn Hg20. Sb203 SnO2 Zn Al Cr. Ba Ca. Ammonium Carbonate: Water: Ba St Ca. Bi Cu20 Hg20 SnO Sb203. Oxides soluble in Potassium Hydrate: Ammonium HTydrate: Pb Sb203 Sn 02 Zn Al Cr. Ag Cd Cu Zn Co Ni. Re-precipitated by boiling: Zn Cr. 4 VOLJUMETRIC AKALYSIS. THE quantitative estimation of a number of medicinal chemicals and their preparations has been much simplified in practice by the volumetric method of chemical examination, which is based upon the fact that chemical substances combine in definite and equivalent proportions, and consists in noting the volume of a test-solution of known strength, required to produce by chemical reaction a certain visible effect when added to a known quantity of the substance under examination. On obtaining this effect, the quantity of the reagent being ascertained, and that of the substance being already known, an accurate estimate may readily be made by equation and simple calculation. By the aid of this simple and rapid mode of examination, the proportion of the constituents of chemical compounds and their preparations may be at once quantitatively estimated. In the following part of this volume, in treating of all those chemicals and preparations in which quantitative determination of the principal constituents is required,-and to which the volumetric mode of examination is best suited, either alone or as a confirmatory test, reference has been made to these pages, in which is stated the quantity of the volumetric test-solution requisite to produce, with a definite weight of the substance under examination, corresponding to its molecular weight, the exact reaction indicative of its officinal strength. VOLUMETRIC ANALYSIS. 51 Volumetric deterlminations are principally based, either upon Saturation, in which the quantity of a base or an acid is measured by the quantity of acid or base which is necessary to convert it into a neutral salt; or, upon Oxidation and Redluction, in which the quantity of the substance to be determined is found by the quantity of chlorine, iodine, or oxygen, to which it is equivalent as an oxidant, or which it requires to pass from a lower to a higher stage of oxidation; or, upon Precipitation, in which case the quantity of the subAli FIG. 15. stance to be determined is derived from that of the reagent required to separate it in an insoluble state. The quantities of the substances to be assayed volumetrically are submitted to examination by weight, gen'erally coincident with their molecular weight, and are expressed either in 52 MANUAL OF CHEMICAL ANALYSIS. grains, or, as is now generally preferred, in grammes; * those of the test-solutions by mieasure in cubic centimetres.t FIG. 16. FIG. 1T. * One gramme is equal to 15.4340 grains of Troy-weight. Although in this work, as pieviously mentioned, the time-honored apothecary's weight has been employed, for all statements of quantities by weight, as still being in general use in pharmaceutical practice in the United'States, Great Britain, and its colonies, yet the metric system of weights and measures has been preferred for volumetric analysis for the above reason, and because the instruments for volumetric analysis are generally constructed with metric divisions. It is obvious, however, that grain weights and corresponding proportions of measures can readily be employed instead of metric units. f A cubic centimetre (Fig. 14) is the volume occupied by one gramme of distilled water at its point of greatest density, 4~ C.; metric measurements, however, are uniformlv taken at 15~.55 C. (60~ F.). FIG. 14. VOLUMETRIC ANALYSIS. 53 The apparatus required for volumetric analysis consists, besides the common utensils, as beakers, funnels, porcelain-capsules, crucibles, stirring-rods, balances, etc., of one or several FIG. 19. GAY LussAC'S BURETTE. FWo. 18. litre-flasks for the preparation of the test-solutions (Fig. 15); these, when filled to a mark on the neck, have mostly a capacity of 1,000 cubic centimetres (1 litre) of distilled water; 54 MANUAL OF CHEMICAL ANALYSIS. some cylindrical, graduated litre-jars (Figs. 16 and 17), divided into 100 or 1,000 centimetre-parts, and used for the preparation of test-solutions as well as for the admixture of parts of a litre; and one or several graduated tubes for the delivery and measureFIG. 20. FIG. 21. 4 GEISLERIS BURETTE. MoiHR's BURETTE, ment of the test-solutions; pipettes and burettes. The former are provided either. with a single mark upon the narrow neck, or are graduated into a number of cubic centimetres or parts thereof. In using pipettes, they are filled by sucking and then VOLUMETRIC ANALYSIS. 55 closed above with the forefinger of the right hand (Fig. 18); the delivery is effected by a more or less gentle displacement of the finger. Burettes are preferable for delivery, and measurement, and are now most generally employed; they hold to a certain nlark 100 or less cubic centimetres, and are divided into a corresponding number of equal parts. I There are three kinds of burettes in luse, which differIII mainly in their construction for delivery: Gay Lussac's I burette, Geisler's burette, and Afohr's burette. I1111111,11111 tf these, Mohr's burette i is now in general use; it I consists of a graduated glass tube, of about half an inch inside width, and about 30 inches in length; to its contracted lower extremity is fitted (Fig. 22) a small piece of caoutchouc tube; into the other end of which a small piece of narrow glass tube, about 1 inch long, is tightly inserted. A strong wire clamp (Fig. 23) closes the rubber tube so that the fluid can only pass through, either in a stream or drop by drop, when the knobs of the FIG. 22. clamp are pressed. Since the correctness of the test depends upon the accurate reading of the height of the test-solution in the burette, a small hollow glass flobat is employed for this purpose (Fig. 24); it is of such a width that it can move freely in the tube without undue friction, and of such a weight that it sinks to more than half its length into the test-liquid. A line is scratched 56 - MANUAL OF CHEMICAL ANALYSIS. around the centre of the float, serving to mark the height of the fluid in the burette. Burettes are conveniently kept for ready use on a revolving stative (Fig. 25). The tests are made by first filling the burette with the testsolution to exactly such height that the mark on the float is coincident with the 0 on the scale of the tube. The solution or mixture to be tested is placed in a beaker-glass under the burette (Fig. 21), and then so much of the test-solution is gradually and carefully delivered into the beaker, with genFIG. 23. ___ tle stirring with a glass rod, as to accomplish the reaction indicative of the completion of __ the operation. A smaller number of cubic centimetres of 17 the test-solution thani 100, and a corresponding amount of substance to be tested, may be employed in any case, and the calculation FIG. 24. made accordingly. In this case smaller and more convenient burettes, holding only 50 c. c., may be employed. ANALYSIS BY SATURATION. ESTI M ATION OF ALKALI E S. Test-Solution of Oxalic Acid. Sixty-three grammes of pure crystallized oxalic acid are dissolved in water; the solution is filtered into a litre-flask, and the filter washed with water until the exact volume of 1 litre, at about 16~ C., is obtained. One hundred cubic centimetres of this solution contain one VOLUMETRIC ANALYSIS. 57 twentieth of the molecular weight, in grammes, of oxalic acid, and are, therefore, capable of neutralizing one-twentieth of the Fw. 25. molecular weig ht in grammes of bivalent bases, or salts containing 2 atoms of univalent metals, or one-tenth of the molectaining 2 atomns of univalent metals, or one-tenth of the toolee 58 MANUAL OF CHEMICAL ANALYSIS. ular weight in graimmes of salts containing one atom of univalent bases. This test solution is applied for the estimation of the alkaline hydrates, carbonates, acetates, tartrates, citrates, and borates: 100 cubic centirnetres of the solution will exactly neutralize, if of officinal strength: 5.61 grammes of. Potassii Hydras (2 oz. aq.). 4.00 " Sodii Hydras (2 oz. aq.). 96.00 " Liquor Potasss, spec. grayv., 1.065. 6.54 " Aqua Ammonia fortior, U. S. P., sppc. grav., 0.900 (2 oz. aq.). T7.00 Aqua Ammonike, U. S. P., spec. grav., 0.960 (1 oz. aq.). 6.91 " Potassii Carbonas pura (2 oz. aq.). 8.30 " Potassii Carbonas depurata (2 oz. aq.). 14.30 " Sodii Carbonas crystallisata (2 oz. aq.). 5.90 " Alnmonii Carbonas (2 oz. aq.). 10.01 i" Potassii Bicarbonus crystallisata (3 oz. aq.). 8.40'" Sodii Bicarbonas (4 oz. aq.). 19.10;" Sodii Biboras (3 oz. aq.). 11.30 "' Potassii Tartras (3 oz. aq.). 18.80 " Potassii Bitartras (3 oz. aq.). 14.10'" Potassii et Sodii Tartras (3 oz. aq.). 13.60 " Sodii Acetas crystallisata (3 oz. aq.). 11.60'" Potassii Acetas (2 oz. aq.). Tile operation is conducted by weighing the above quantity of the substance, or the preparation to be estimated, placing it in a beaker, and, when required, diluting or dissolving it in the quantity of water stated in parentheses for each member of the above list. The tartrates and acetates have first to be completely reduced to carbonates, by ignition in a small covered porcelain crucible. When the solution is ready for the test, one or a few drops of litmus-solution are added, so as to impart to it a distinct bluish tint; then the bealer is placed under the burette containing the test-solution (Fig. 26), and, with constant gentle stirring with a small glass rod, the test-solution is delivered into the beaker, first in a stream, and, when approaching the point of saturation, drop by drop, until the blue assumes a violet hue; the solutions of carbonates have to be heated before approaching saturation, in order to expel the VOLUMETRIC ANALYSIS. 59 carbonic-acid gas from the solution as nearly as possible, and thereby to lessen its reaction upon litmus. These operations require care and skill in every point, so as to avoid the slightest loss of either of the liquids, and a consequent error in the result. When saturation is indicated by the violet-reddish color of the liquid, the process is complete, and the volume of test-acid employed is read off. The number of cubic centilnetres employed, less than 100, indicates at once the percentage of impurities or of want of strength. A On the other hand each _ cubic centimetre of the test-so- - lution employed corresponds 2 to one milligramme-molecule of hydrate or one-half milli- FIG. 26 gramme-molecule of carbonate, i. e.: 1 cubic centimetre corresponds to 0.056 gramme Potassii Hydras, 1 t;" " 0.069 6" Potassii Carbonas, 1 (:" " 0.040 " Sodii Hydras, I " " 0.053 " Sodii Carhonas (anhydrous), and a simple equation gives the amount of alkaline hydrate or carbonate present. By operating on 100 times the half-milligramme-molecule, i. e., 6.9 grammes of potassium carbonate or 5.3 grammes of sodium carbonate, all calculation is dispensed with; for, as this amount, if present, would require 100 cubic centimetres of oxalic-acid test-solution for its saturation, the 60 MANUAL OF CHEMICAL ANALYSIS. number of cubic centimetres actually required, at once indicates the percentage of alkaline carbonate. When, in estimating alkaline carbonates, the amount of carbonic acid, namely, the percentage of real carbonate, has to be determined, the following mode is simple and accurate: Two small, light glass flasks with twice-perforated rubbercorks, are connected with a twice-bent tube c (Fig. 27); the flask A is provided with the tube a reaching to the bottom of the flask, and closed at its outer end with a globule of soft wax; that d I ____c__ 11 of B is provided with the short tube d. Fifty grains of the carbonate under examination are weighed, and introduced into the A~- flask A, together with a little wad:: D mter; the flask B is half filled with concentrated sulphuric acid; the __ _ _ _ M-Adz apparatus is then tightly fitted, and weighed. A small quantity of air is now sucked out of flask B Fw,,. 27. by means of the tube d, whereby the air in A is likewise rarefied. On allowing the air to return, a quantity of the sulphuric acid ascends to the tube c, and flows over into flask A, causing a disengagement of carbonic-acid gas, which escapes through the tube d, after having been dried by passing through the acid in B. This operation is repeated until the whole of the carbonate is decomposed, and the process is terminated by opening the wax stopper, and drawing some air through the apparatus by sucking on tube d. The apparatus is then reweighed, and the difference of the two weighings expresses the quantity of carbonic acid in the 50 grains of carbonate under examination. ESTIMATION OF ACIDS. Test-Solution of Sodium HITydrate. One hundred cubic centimetres of the test-solution of oxalic acid are placed in a beaker with a little neutral litmus-solution, the measure rinsed out, and the washings poured into the beak VOLUMETRIC ANALYSIS. 61 er. Then a strong solution of sodium hydrate is allowed to flow into the oxalic-acid solution until exact neutralization ensues; the quantity of the soda-solution is noted, and, to every similar quantity of the whole bulk of the sodium-hydrate solution, water is added until the whole measures 100 volume-parts. It, for instance, 93 cubic centimetres of soda-solution have neutralized the 100 cubic centimetres of acid, then, 7 cubic centimetres of water must be added to 93 cubic centimetres of the soda-solution, or 70 to 930 to make a litre. Simple proportion will show to what extent any other quantity is to be diluted. One hundred cubic centimetres of this test-solution of sodium hydrate contain one-tenth of the molecular weight (= 4) of sodium hydrate taken in grammnes, and will neutralize an equal quantity of an acid. This test-solution is employed for the estimation of the following medicinal acids: One hundred cubic centimetres of the solution will neutralize, if of officinal strength: 16.70 grammes of Acidurn aceticum, U. S. P., spec. grav., 1.047. 140.58 " Acidum aceticum dilutum, U. S. P., 1.006. 7.00 " Acidurn citricum. 11.48 " Acidumr hydrochloricum, U. S. P., Spec. gray., 1.160. 47.77 " Acidum hydrochloricum dilutum, U. S. P., Spec. gray., 1.038. 9.00 " Acidum nitricum, U. S. P., Spec. gray., 1.420. 54.33 " Acidurn nitricum dilutum, U. S. P., Spec. grav., 1.068. 5.06 " Acidum sulphuricum, U. S. P., Spec. grav., 1.843. 37.18 " Acidum sulphuricum dilutum, U. S. P., spec. grav., 1.082. 7.50 " Acidum tartaricum. The concentrated acids are to be diluted withg four or five times their volume of water, and the solid ones to be dissolved in about eight times their weight of water before being tested. To indicate saturation, and the consequent termination of the test, litmus-solution is used, as before; and the mode of operation is similar to that described on page 58. The number of 62 ~ ~MANUAL OF CHEMICAL ANALYSIS. cubic centimetres employed for saturation, less than 100, indicates at once the percentage of impurities or want of strength. ANALYSIS BY PRECIPITATION. ESTIMATION OF ACIDULOUS RADICALS PRECIPITATED BY ARGENTIC NITRATE. Test-Solittion of Argentie Nitrate. Seventeen grammes of pure crystallized argentic nitrate are dissolved in water; the solution is filtered into a litre-flask, and the filter washed with so much water as to make up the exact volume of one litre. One hundred cubic centimetres of this solution contain one one-hundredth of the molecular weight, in grammes, of argentic nitrate, and will decompose an equivalent quantity of a salt of any base which yields silver compounds insoluble in water. This test-solution is employed for the estimation of the following officinal preparations, and 100 cubic centimetres of it will require, for complete decomposition of the argentic nitrate: 27.00 grammes of Acid.um hydrocyanicum dilutum, U. S. P. 1.19 " Potassii Bromidum. 1.66 " Potassii Iodidum. 1.50 " Sodii Iodidum. In testing hydrocyanic acid, it is, before delivering the testsolution into'it, slightly over-saturated with a solution of potassium hydrate. The test-solution is then added, until, after constant stirring, a slight permanent turbidity remains. The quantity of argentic nitrate employed represents exactly half the amount of hydrocyanic acid present, and has therefore to be doubled in order to indicate the correct percentage. The bromides and iodides are dissolved in one ounce of water, and the test-solution is added until, after agitation of the liquid and subsidence of the precipitate, a drop of the testsolution ceases to cause further precipitation. The quantity of argentic nitrate employed represents an equivalent amount of the bromide or iodide. VOLUMETRIC ANALYSIS. 63 ANALYSIS BY OXIDATION. Test-Solzution of Iodine. 12.7 grammes of pure iodine, and 18 grammes of potassium iodide, are dissolved in about 12 ounces of water; the solution is filtered into a litre-flask, and the filter washed with so much water as to make up the volume of one litre. One hundred cubic centimetres of this solution contain one one-hundredth of the atomic weight of free iodine in grammes, and, if water be present, will cause the oxidation of one two-hundredth of the molecular weight of arsenious acid in grammes, or one four-hundredth of the molecular weight of common white arsenic in grammes, arsenic acid being produced. One hundred cubic centimetres of this test-solution require for oxidation of the following officinal preparations: 0.495 grammes of Acidum Arseniosum. 68.30'" Liquor Potassii Arsenitis, U. S. P. 2.48 " Sodii Hyposulphis. The arsenious acid is dissolved, together with about 2 grammles of sodium bicarbonate, in 2 ounces of boiling water; when cool, a little mucilage of starch is added, and the testsolution delivered into the arsenious solution until a permanent blue coloration ensues. The Liquor Potassii arsenitis is boiled, after adding about 1~ grammes of sodirum bicarbonate, and, when cool, is tested in like manner. The Sodium hyposulphite is dissolved in 2 ounces of water, and a little mucilage of starch added. ANALYSIS BY DEOXIDATION. Yest-Solution of Sodiumy HI]yp2osu4up/ite. Thirty gramrnmes of sodium hyposulphite are dissolved in nearly one litre of water; the solution is allowed to flow from a burette into a beaker containing exactly 100 cubic centimetres of the volumetric solution of iodine, until the brown color of the iodine just ceases-or, if a little mucilage of starch be added, until the blue iodide of starch is decolorized. The 64: MANUAL OF CHEMICAL ANALYSIS. number of cubic centimetres of the solution required is noted, and so much water is added to the bulk of the solution, that 2.48 grammes of sodium hyposulphite are contained in every 100 cubic centimetres. This test-solution contains one one-hundredth of the molecular weight of sodium hyposulphite in grammes, and will indicate the presence of one one-hundredth of the atomic weight of iodine in grammes, in any quantity of a liquid containing free iodine, or iodine liberated by an equivalent quantity of free chlorine. 100 cubic centimetres of this solution require for exact deoxidation: 1.27 grammes of Iodinum. 5.42 fluid-drachms of Tinctura Iodini, U. S. P. 54-58 grammes of Aqua Chlorini. 1.17 " Calx Chlorinata. The iodine is dissolved in about 3 ounces of water, together with 1.5 grammes of potassium iodide; the test-solution is added until the brown color just disappears; or the solution is blued with a trace of mucilage of starch, and the test-solution added until the blue color disappears. The chlorine-water is mixed with'an equal bulk of water in which about 1~ grammes of potassium iodide have been dissolved. Mucilage of starch is also employed to indicate the termination of the test. The chlorinated lime is mixed with about 3 ounces of water, in which 31 grammes of potassium iodide have been dissolved; the mixture is subsequently acidulated with dilute hydrochloric acid, and a little mucilage of starch is added before delivering the test-solution into it, which is done until the blue color just ceases. PART SECOND. THE MEDICINAL CHEMICALS AND THEIR PREPARATIONS, THEIR PHYSICAL AND CHEMICAL CHARACTERISTICS, WITH DIRECTIONS FOR THE EXAMINATION OF THEIR QUALITY AND PURITY. THE MEDICINAL CHEMICALS AND THEIR PREPARATIONS. ACETUX. Vinegar. VINEGAR contains, on the average, from 4T to 6 per cent. of mono-hydrated acetic acid; when of this strength, one fluidounce requires for saturation not less than 35 grains of crystallized potassium bicarbonate; and 50 cubic centimetres of the volumetric test-solution of sodium hydrate will saturate 70.29 grammes of vinegar, corresponding to 5 per cent. of anhydrous acetic acid. Examination: MXineral acids are indicated when about half an ounce of the vinegar is thoroughly mixed and boiled for five minutes with half a grain of starch; when cool, one drop of solution of iodinized potassium iodide is added; if any free mineral acid be present, it acts on the starch, transforming it into glucose, and consequently prevents the formation of blue iodine-starch. Sulphuric and hydrochloric acids. A crude mode of detecting the presence of sulphuric acid in vinegar consists inl evaporating, by a gentle heat, a small portion of it after the addition of a few grains of cane-sugar, in a porcelain capsule, to the consistence of a thick syrup; this will become almost black, if free sulphuric acid be present. Since the water and the materials used for the preparation of vinegar generally contain traces of sulphates and chlorides, 68 MANUAL OF CHEMICAL ANALYSIS. most vinegar yields a slight turbidity with barium and argentic nitrates. In order to ascertain the presence of either of these acids in a free state, about half an ounce of the vinegar is distilled from a small flask, the recipient being cooled in ice-water FIG. 28. (Fig. 28); when about one drachm of distillate has been obtained, this is preserved for examination for aldehyde; another receiver is applied, and the distillation continued until almost the entire fluid has distilled over and the scanty residue commences to become dry and dark. The distillate is then acidulated with a few drops of nitric acid, and tested with barium nitrate for sulphuric acid, and with argentic nitrate for hydrochloric acid. The presence of sulphuric acid may also be detected, or verified, by reducing about one ounce of the vinegar by evaporation, in a porcelain capsule, upon a water-bath, to the consistence of a thick syrup, which, when cool, is thoroughly mixed with about half a fluidounce of strong alcohol, and allowed to stand in a corked test-tube, with occasional agitation, for about an hour; the filtrate is then mixed with about half an ounce of distilled water, is acidulated with a few drops of diluted nitric acid, and tested with a few drops of solution of barium nitrate; an ensuing white precipitate, not disappearing on dilution with water, proves the presence of sulphuric acid. Sulphutrous acids and sulphites may be detected by a green ACIDA. 69 ish coloration of the vinegar, when about two drachms of it are warmed with one drop of solution of potassium bichromate. Nitric acid may be detected by adding one drop of neutral indigo solution to about half an ounce of the vinegar in a testtube, and warming the mixture by dipping the tube into hot water; a discoloration of the bluish or bluish-greenish tint of the liquid will indicate free nitric acid; when the color remains, one or two drops of concentrated sulphuric acid are added while warn; if discoloration takes place now, nitrates are-indicated..Wetallic impurities are detected by saturating the vinegar with hydrosulphuric-acid gas, and allowing the fluid to stand for a few hours; an ensuing white turbidity would indicate tin or sulphurous acid; a dark one lead and copper, which may be discriminated by collecting and washing the precipitate, obtained by a repetition of the test on a larger scale, upon a filter, and dissolving it in nitric acid; the solution is examined in two portions, the one by over-saturation with ammonium hydrate, the other by addition of one or two drops of diluted sulphuric acid; a blue coloration in the first instance indicates colper, a white precipitate, in the second one, lead. Aldehyde may be detected in the first portion of the distillate obtained and preserved in the second test; it must be void of alcoholic odor or taste, and must not become yellow or brown, when mixed and warmed with an equal bulk of strong solution of potassium hydrate; such coloration would indicate aldehyde. Acrid vegetable substances are detected by saturating a portion of the vinegar with magnesium carbonate, and by subsequent evaporation of the filtrate, at a gentle heat, to about onethird of its volume. Acrid vegetable substances may then be recognized by their odor and taste. ACIDUM ACETICUM. Acetic Acid. Acetic-acid hydrate, or monohydrated acetic acid, contains one molecule (15 per cent.) of water, and forms, below 15~ C., large, colorless, transparent crystals (glacial acetic acid), which, TO BIBMANUAL OF CHEMICAL ANALYSIS. above 16 to 180 0., fuse to a thin, colorless liquid of a pungent odor and strong acid reaction, having a spec. grav. of 1.063; it boils at 120~ Cf., yielding very pungent and acid inflammable vapors. Acetic acid hydrate is miscible in all proportions with water, alcohol, and ether, and dissolves albumen, fibrin, camphor, and many resins, gum-resins, and essential oils; diluted with water, it forms the commercial and medicinal acetic acids, which maintain the character of acetic acid as long as the admixture of water does not exceed 18 to 19 per cent., beyond which dilution the acid loses more or less the character of a strong acid, and its solvent properties for the abovementioned substances. Acetic acid is recognized, either free or combined, by yieldding a deep-red color with solutions of ferric salts, and, when not too much diluted, by the odor of acetic ether, when heated with a mixture of equal parts of alcohol and concentrated sulphuric acid. Two strengths of acetic acid are officinal: Acidum Aceticum of the spec. grav. of 1.047 (1.044 British Pharmac., 1.064 Pharm. German.), and Acidum Aceticum dilutum of the spec. grav. of 1.006 (1.040 Pharmac. German.). The strong acid of 1.047 spec. gray. contains 28 per cent. of anhydrous, or 36 per cent. of monohydrated, acetic acid, and 100 parts of it require 60 parts of crystallized potassium carbonate for saturation; the diluted acid of 1.006 spec. grav. contains 3.63 per cent. of anhydrous acid, and 100 parts of it saturate 7.6 parts of crystallized potassium bicarbonate. The strength of aqueous acetic acid cannot be correctly inferred from its specific gravity, since its density is increased to a certain extent by contraction, the spec. grav. of 1.0735 being the maximum density, below which it again decreases; for instance: a mixture of one molecule of monohydrated acetic acid with three molecules of water has the same specific gravity as a mixture of one molecule of the acid with nine molecules of water, namely, 1.0686. The strength of acetic acid may be determined by observing the exact quantity of crystallized potassium bicarbonate required to saturate a known weight of the acid, and by subsequent equation; or by treating a known weight of the acid with an excess of barium carbonate, and by ACID A. calculating its strength from the amount of carbonate decomposed, which is ascertained by deducting the weight of the remaining undissolved carbonate from the total amount used, and by dividing the remainder by 1.933; the quotient indicates at once thle quantity of monohydrated acetic acid contained in that quantity of the acid. The readiest mode of ascertaining the strength of acetic acid, is the volumetric estimation with test-solution of sodium hydrate (page 60). Sixty parts by weight (the molecular weight) of anhydrous acetic acid require for exact saturation 40 parts (the molecular weight) of sodium hydrate; since 1,000 cubic centimetres of the test-solution contain 40 grammes of sodium hydrate, these saturate exactly 60 grammes of anhydrous acetic acid. Upon this equation the calculation for the strength of acetic acid may be based: for instance, an acid, of which 182.0 grammes saturate 1,000 cubic centimetres of test-solution, contains 33 per cent. of anhydrous acid; an acid, however, of which the same quantity is saturated by 930 cubic centimetres of the test-solution, contains, therefore, only 30.7 per cent. of anhydrous acid. In order to secure accurate results in the volumetric estimation of acetic acid, alkanet-tincture is preferably used as the indicator of saturation, since the alkaline acetates, though neutral in combination, have an alkaline reaction on litmus. Examination: Empyreuma betrays itself by its odor; small traces, however, may be recognized by neutrllizing a little of the acid with Liquor Potassoe, and by tingeing it subsequently faintly with potassium permanganate, and by gently heating it. Sz2phuric and hydrochloric acid may be detected by testing separate portions of the diluted acid with barium nitrate for the former, and with argentic nitrate for the latter. Sulphurous acid is indicated by a greenish coloration, when a little of the acid is heated with a few drops of solution of potassium bichromate; it may also be recognized when a mixture of about one drachm of the acid with two drachms of diluted hydrochloric acid and two drachms of water, is poured upon a little pure granular zinc in a large test-tube, and the mouth of the tube is at once loosely closed with a bunch of 72 MANUAL OF CHEMICAL ANALYSIS. cotton moistened with solution of plumbic acetate (Fig. 29); if sulphurous acid be present, the plumbic solution will become dark, or black. Nitric acid may be detected by discoloration when a little of the acid is tinged slightly blue with one drop, or part of a drop, of neutral indigo-solution and heated. EIG. 29. Metallic imnutrities are detected by mixing the acid with about two or three times its bulk of hydrosulphuric acid, or, when diluted acid is under examination, by saturating it with hydrosulphuric-acid gas, and allowing the liquid to stand ACIDA. 73 in a corked test-tube in a warm place for several hours; an ensuing white precipitate would indicate tin or zinc (if no sulphurous acid be present, which also causes a white turbidity with the reagent), a black one lead or copper; in the latter case, the precipitate may be collected and washed upon a filter, and then dissolved in a few drops of warm, strong nitric acid, and then diluted with a few drops of water; this solution is tested in two separate portions, the one by over-saturation with almonium hydrate, the other with one drop of dilute solution of sodium sulphate; a blue coloration in the first test would indicate cop. per, and a white precipitate, in the second one, lead. ACIDUX ARSENIOSUM. ACIDUM ARSENICOSUM. ARSENICU3I ALBUM. Arsenious Acid. White Arsenic. Arsenious acid occurs in two polymeric crystalline forms, and in the amorphous state; the latter one being the commercial white arsenic. When freshly prepared, it forms heavy, transparent, glassy cakes, with smooth conchoidal fracture, and has a spec. grav. of 3.738; this becomes gradually opaque and porcelain-like by passing into the crystalline state, which change proceeds from the surface toward the inside; at the same time its density is slightly diminished (3.689), and its solubility in water increased. In consequence of the sinultaneous occurrence of the amorphous and the crystalline modifications, and the difference in their solubilityv, the statements of the solubility of arsenious acid in water are slightly at variance. The amorphous glassy, and the commercial powdered, acid is soluble in 10 to 12 parts of boiling, and 30 parts of cold, water; it is almost insoluble in alcohol and insoluble in ether, but freely soluble in the alkaline hydrates and in -warm diluted acids, especially in hydrochloric and tartaric acids, from which latter solutions it deposits, on cooling, in small transparent octahedial crystals. Arsenious acid volatilizes at about 218~ C. without fusion, forming a colorless, inodorous vapor which solidifies, on cool MANUAL OF CHEMICAL ANALYSIS. ing, in small transparent and brilliant octahedrons; but when heated, in contact with reducing-agents, such as potassium cyanide, organic substances, and carbon, the acid is reduced to metallic arsenic, which sublimes and deposits in a brilliant metallic crust when the reduction is carried on in a glass tube (Fig. 30), emitting, at the same'time, a peculiar and characteristic odor, somewhat similar to garlic. FIa. 30. The aqueous solution of arsenious acid has a feeble acid reaction on litmus; it yields a white precipitate with lime-water, a yellow one with hydrosulphuric acid, soluble in aqua ammoniae; argentic nitrate and cupric sulphate produce only a turbidity in solutions of arsenious acid; upon the addition of an alkali, however, a yellow precipitate is formed with the former reagent, and a brilliant green one with the latter, both precipitates being soluble. in excess of ammonia, and the argentic one also in nitric acid. Solution of arsenious acid, when mixedwith either hydrochloric or sulphuric acid, and the mixture allowed to act on metallic zinc or magnesium, gives rise to the formation of hydrogen arsenide simultaneously with the formation of hydrogen sulphide, which has an alliaceous odor, and burns with a bluishwhite flame, depositing a brilliant black spot on cold surfaces held in the jet (M[arsh's test). When solution of arsenious ACIDA. 7 acid is mixed with an excess of concentrated hydrochloric acid, and a piece of bright copper-foil immersed and boiled, it deposits the reduced arsenic upon the copper, coating it with a darkgray metallic film (Reinsch's test); when the same test is made, taking tin-foil (real), or stannous chloride, instead of copper, the tin becomes equally coated with arsenic, and, at the same time, a voluminous brown deposit is formed (BettendorJ's test). Examination of Powdered White Arsenic: Jineral admixtures are recognized and left behind when a little of the white arsenic is either volatilized at a red heat, or dissolved in an excess of boiling liquor potassse or hydrochloric acid. When an insoluble residue is left from either of these solutions, it is washed, and, when dry, is mixed and fiused in a porcelain crucible with four times its weight of a mixture of equal parts of exsiccated carbonates of sodium and potassium; the obtained fused mass is triturated and boiled with a sufficient quantity of water, and the filtered solution tested with barium nitrate for sulphates (calcium and barium sulphates). The residue on the filter is washed and treated with warm diluted hydrochloric acid. and the filtrate subsequently tested with sodiumn sulphate for barizum, and, in another portion, nearly neutralized with aqua ammonim, with ammonium oxalate for calcium. One hundred grains of arsenious acid, when dissolved in boiling diluted hydrochloric acid, yield, upon complete precipitation with hydrosulphuric acid, a precipitate of arsenious sulphide, which, when collected upon a tared filter, washed, and dried, should weigh 124 grains. ACIDUM BENZOICUX. ACIDUM BENZOICUMI SUBLIIATUM. FLORES BENZOES. Benzoic Acid. Colorless, soft, feathery needles, of a silky lustre, inodorous when cold and pure, but of a faint smell when gently warmed. The agreeable aromatic odor of the officinal benzoic acid is due 76 BMANUAL OF CHEMICAL ANALYSIS. to traces of essential oil. When derived from solutions, benzoic acid forms colorless, pearly needles or laminae of six-sided prisms. When warmed, the acid begins to volatilize below 100~ C.; melts at 121~ C., forming a colorless liquid, which, on cooling, solidifies; at 1450 C. it evaporates freely, and at near 2i0O C. it boils, without decomposition, emitting an acrid, irritating vapor, which readily inflames, burning away without residue. Benzoic acid is soluble in about 200 parts of cold, and 25 parts of boiling, water, in 10 parts of' glycerin, and freely in alcohol, ether, oil of turpentine, and many essential and fatty oils, and also in solutions of the alkaline hydrates. Concentrated nitric and sulphuric acids dissolve benzoic acid more or less without decomposition; on addition of water it is precipitated unaltered. A concentrated solution of benzoic acid in aqua ammonite, in which the ammonium hydrate is nearly neutralized, gives, on addition of a few drops of solution of a ferric salt, a copious reddish-yellow precipitate of ferric benzoate, which, on addition of hydrochloric acid, disappears, while the benzoic acid is precipitated, redissolving on addition of ether or alcohol. Examination: Hipypuric acid, as is well known, is resolved by the action of hydrochloric acid, and other agents, into benzoic acid and glycocine, and much benzoic acid is obtained from this source. Such acid, however, differs in some of its chemical properties from the benzoic acid derived from the benzoic resin, especially in the degree of solubility of its salts in water and alcohol, and in its deportment with potassium permanganate; this difference extends very likely also to their physiological and therapeutical action, and the acid derived from hippuric acid cannot yet be considered as admissible for medicinal use. Itippuric acid may be distinguished from, or recognized in, benzoic acid, by heating in a test-tube a mixture of about 20 grains of the acid with 50 grains of dry potassium hydrate, and about 50 drops of water; if hippuric acid is present, it will be indicated by a faint odor of ammonia, and by white vapors with a glass rod moistened with acetic acid and held over the orifice of the test-tube, as well as by blackening a strip of un ACIDA. 77 sized paper moistened with solution of mercurous nitrate, and held in the mouth of the test-tube. Hippuric acid, and the benzoic acid derived therefrom, may be distinguished from, or recognized in, true benzoic acid by agitating about 5 grains of the acid with 4 fluid-drachms of water, in a test-tube, and by adding so much solution of potassium permanganate as to tinge the mixture deep violet; it is then heated to from 500 to 60() C., by dipping the tube into water of that temperature; the violet color will remain for at least five minutes with true benzoic acid, while it will become distinctly red within that time with hippuric acid, or benzoic acid derived therefrom. An additional test may be made by tingeing a solution of 5 grains of the acid, in 3 fluid-drachms of liquor potasse, deep violet with solution of potassium.permanganate, and by boiling this solution for a few minutes; the solution of true benzoic acid becomes green; that of hippuric-benzoic acid, yellow, or even colorless, with the separation of brown manganic oxide. Cinnarnomic acid may be detected by the odor of oil of bitter alnonds, when a mixture of the acid with potassium bichromnate and strong sulphuric acid, or of a concentrated aqueous solution of the acid, is heated with potassium permanganate. Sugar is indicated by the odor of caramel, and by intumescence, when a few grains of the acid are gradually heated in an iron spoon. Mineral substances, not readily volatilizable or soluble in alcohol, may at once be detected by a residue left on volatilization, as well as upon solution of the acid in alcohol. If any fixed residue is left, it may be dissolved in warm water acidulated with nitric acid, and tested with barium nitrate for sulphates, and with argentic nitrate for chlorides and phosphates. Boric accid may be recognized by the green coloration of the flame of burning alcohol, previously saturated with the acid. 78 MANUAL OF CHEMICAL ANALYSIS. ACIDUX BORACICUM. ACIDUM BORICUM. Boracic Acid. Boric Acid. Colorless, translucent, pearly, six-sided scales, somewhat unctuous to the touch. They contain 3 molecules (42.16 per cent.) of water, two of which are water of crystallization; when heated upon platinum-foil, the latter is readily evaporated, while the other molecule does not part unless heated to redness, when the anhydrous acid melts, forming a glassy, transparent fuse, which is a solvent for most metallic oxides, and which solidifies to a fissured glass on cooling. Boracic acid is soluble in 26 parts of cold, and in 3 parts of boiling, water, which solution has but little taste and feebly affects blue litmus-paper, while it renders turmeric-paper reddish brown, quite different from the color produced by alkalies, and becoming more distinct after drying. The acid is also soluble in alcohol, and the solution burns witli a green-edged flame. Examination: About 10 grains of the crystals of boric acid are added to 1 drachm of water in a test-tube, and heated; a clear and complete solution must take place, and, when part of the hot solution is dropped into alcohol, no turbidity or precipitate must ensue; otherwise the presence of admixtures insoluble or less soluble in water or alcohol is indicated. C]hlorides and sulphcates are detected in the aqueous solution acidulated with nitric acid, by argentic nitrate and barium nitrate respectively. ACIDUM CARBOLICUM. ACIDUM PHENYLICUM. Carbolic Acid, or Phenylic Acid. Phenol. Phenic Alcohol. Pure carbolic acid forms, at temperatures below 410 C., rhomboidal needles or crystalline masses consisting of such; when not quite pure, they become frequently more or less red ACIDA. 79 dish; at temperatures above 41~ C., pure carbolic acid forms an oily, colorless liquid, which boils at about 1820 C.; its spec. grav. is 1.060 to 1.065; it absorbs moisture on exposure to the air, and gradually deliquesces; it dissolves about one-tenth of its weight of water, and then remains liquid far below its melting-point. Pure carbolic acid dissolves to some extent in water,* and is freely miscible with alcohol, ether, chloroform, glycerin, acetic acid, and the volatile and fatty oils; its aqueous solution does not react upon test-paper, coagulates albumen and collodion, and assumes a violet-blue color upon the addition of a few drops of a dilute solution of neutral ferric chloride. Carbolic acid is miscible with concentrated sulphuric acid, with a slight evolution of heat, without apparent change; it yields a more or less violent reaction with concentrated nitric acid, and with chlorine and bromine; it is also soluble in the alkaline hydrates, and combines with them, and with other salifiable bases, forming neutral salts, which, however, maintain the alkaline reaction, and are decomposed by all acids. The pure commercial carbolic acid contains mostly a slight quantity of cresol, and perhaps of other homologous aromatic alcohols, which do not modify the principal properties of pure phenol, except that they lower its melting-point, and apparently decrease its solubility in water, which may also be influenced with pure phenol by a slight quantity of water. Examination: The quality of carbolic acid is sufficiently recognized by the above characteristics, by its odor, and by its appearance; in order to detect admixtures, the fused acid may be tested by mixing it with twice its volume of liquor potasse, and warming the mixture by immersing the test-tube in boiling water; a complete solution should take place, which, when cold, should remain limpid, and not separate any oily liquid upon dilution with three times its bulk of water. * The United States Pharmacopoeia states that carbolic acid is soluble in from 20 to 33 parts of water, the purest being the most soluble. The Pharmacopoea Germanica states the proportion of solubility as 1 part of the acid to from 50 to 60 parts of water. 80 MANUAL OF CHEMICAL ANALYSIS. ACIDUMI CHROMICUIIf. Chromic Acid. Brilliant crimson-red acicular crystals or crystalline masses, of an acid, metallic taste; very deliquescent, and therefore frequently of a humid appearance. At a heat between 1800 and 190~ C., they melt into a reddish-brown liquid, which, on cooling, forms a red, opaque, and brittle mass. Chromic acid is freely soluble in water and alcohol, forming orange-yellow solutions. It is a powerful oxidizing agent, and decomposes organic matters. When its aqueous solution is heated, after the addition of a few drops of hydrochloric acid and a few drops of alcohol, the orange-red color of the liquid becomes yellowish green, with the evolution of ethereal vapors. When dissolved in an aqueous solution of sulphurous acid, it forms immediately a green solution. Examination: Sulp4huric acid may be detected by boiling a diluted solution of the acid, to which a few drops of hydrochloric acid and a little alcohol have been added, until the liquid appears green. Part of it is then tested with barium nitrate; an ensuing white precipitate would indicate sulphuric acid. Potas8ium bichromate may be detected in the rest of the green solution, by evaporating it, in a porcelain capsule, nearly to dryness, and by subsequent solution of the residue in a few drops of water; the filtered solution is tested with sodium bitartrate; an ensuing white crystalline precipitate would indicate potassium. ACIDUM CITRICUX. Citric Acid. Colorless rhomboidal prisms with dihedral summits, permanent in the air, but slightly efilorescent in a dry and warmn atmosphere, and becoming moist in a damp one. Exposed to a strong heat, the acid fuses, and is wholly dissipated, with the evolution of empyreumatic vapors. ACIDA. 81 Citric acid dissolves in three-fourths of its weight of cold, and in half its weight of boiling, water, and is also soluble in alcohol, forming sour solutions of an acid reaction; the aqueous solution, when exposed to the air, is subject to gradual and spontaneous change; it forms no precipitate with potassium salts (except the tartrates), and, when sparingly added to limewater, so that the alkaline reaction still remains prevalent, it does not render it turbid (distinction from oxalic, tartaric, and racemic acids); when, however, the liquid is warmed and agitated, it becomes turbid, but transparent again upon cooling. Sixty grains of citric acid neutralize 70.41 grains of potassium carbonate, 85.71 grains of potassium bicarbonate, 120.24 grains of crystallized sodium carbonate, 72 grains of sodium bicarbonate, and 40.92 grains of magnesium carbonate. Voblumetric Estimation, see page 61. Examination: In order to obtain an average sample of the crystallized acid for examination, it is advisable to grind several ounces of the crystals, and to make from a small portion of the powder two solutions: an aqueous one, in the proportion of 1 part of the acid to 4 parts of water; and an alcoholic one, in the proportion of 1 part of acid to 6 parts of alcohol. Both the solutions should be complete and clear. Tartaric acid is detected as a granular white precipitate, when 2 fluid-parts of the aqueous solution and 1 fluid-part of the alcoholic solution are mixed together and agitated with 1 fluid-part of a strong solution of potassium acetate. When many samples of the crystallized acid hav6 to be examined, the following method is also applicable: A large glass pane is placed upon ultramarine-blue or darkbrown paper on an horizontal table or board; a solution of potassium hydrate in diluted alcohol (15 grains of dry potassium hydrate in 6 drachms of distilled water and 2 drachns of strong alcohol) is then spread over the pane as thick as will remain stationary upon it; a number of crystals and fragments thereof are now placed a little apart from each other, the crystals of each sample separate. Instead of a glass pane, small plates may be employed. Agitation being carefully avoided, 6 82 MANUAL OF CHEMICAL ANALYSIS. the citric-acid crystals, after several minutes' action of the alkaline solution, appear clearer and more transparent; if crystals of tartaric acid be present, they will be recognized by their cloudy and white appearance; after two or three hours, the crystals of citric acid are nearly or quite dissolved, and in their stead is frequently left a small, delicate, dust-like spot (due to traces of calcium salts); if crystals of tartaric acid be present, they will appear whitish, covered with a coat of small transparent acicular crystals, and surrounded by a deposit of small overlapping groups of similar crystals, or a thin, though broad, crystalline film (all crystals of potassium bitartrate). iietallic imrpurities may be detected in the aqueous solution, by a dark coloration or turbidity with hydrosulphuric acid; if it be so considerable as to form a deposit, this is collected and washed upon a filter, and then dissolved in a few drops of warm nitric acid; the obtained solution is divided into two portions, one of which is examined by over-saturation with aqua ammnoniae for copper, which will be indicated by a blue coloration, and the other with one drop of diluted sulphuric acid forilead. Sulphlates may be detected in the diluted aqueous solution, to which a few drops of diluted nitric acid have been added, by a white precipitate with barium nitrate. ACIDUM GALLICUlM. Gallic Acid. Small acicular prisms or silky needles, or a crystalline powder, nearly colorless, or of a pale fawn-color. They contain 2 molecules (9.5 per cent.), of water of crystallization, which pass off at about 1000 C.; at about 215~ C., the acid is resolved, without fusing, into carbonic acid and pyrogallic acid, which latter sublimes in small crystalline plates; when exposed to a strong heat, with free access of air, gallic acid burns away without residue. Gallic acid is soluble in 100 parts of cold, and in 3 parts of boiling, water; it is also soluble in cold, and freely in boiling, alcohol, but less soluble in ether and glycerin. The aqueous ACIDA. 83 solution has an acidulous and astringent taste and an acid reaction, and is liable to spontaneous decomposition on exposure to the air; it gives no precipitate with solutions of ferrous salts, if free from ferric salt, but it gives a bluish-black precipitate with solutions of ferric salts, the color of which disappears when the liquid is heated, from the deoxidation of the ferric to ferrous salt, at the expense of the gallic acid. A solution of gallic acid, when dropped into lime-water, produces a white turbidity, which soon becomes blue, and passes through a greenish or violet tint to a purple color. The solution forms no precipitate with argentic nitrate, but reduces it to metallic silver, gradually at common temperature, at once when heated. Solutions of the alkaline hydrates, as well as concentrated sulphuric and nitric acid, when poured upon dry gallic acid, dissolve it, with a deep-red color. Examination: Tannic acid may be detected by a white precipitate, when the solution of the acid is added to a dilute solution of gelatin. Sugar and dextrin remain behind upon solution of the acid in strong alcohol. Resinous admixtures will remain behind and separate on cooling, floating on the surface when a few grains of the acid are dissolved in boiling water. ACIDUM HYDROCHLORICUM. ACIDUM MURIATICUM. Muriatic Acid. Hydrochloric Acid. Concentrated hydrochloric acid is a colorlessfuming liquid, of a pungent and suffocating odor and corrosive taste; its spec. gravity depends upon the quantity of hydrogen chloride held in solution, and varies in the strong acid between 1.160 and 1.120, corresponding to 32 and 242 per cent. of the anhydrous hydrochloric acid. The crude commercial acid has generally a spec. grav. of from 1.160 to 1.180, containing 32 to 35 per 84 MANUAL OF CHEMICAL ANALYSIS. cent. of the gas and various impurities, which impart a yellowish color to the acid. Hydrochloric acid may further be recognized by the evolution of chlorine gas when heated in a test-tube with black manganic dioxide, and, when diluted, by a white curdy precipitate with argentic salts, which is insoluble in acids, but soluble in ammonium hydrate and in potassium cyanide, and which becomes black on exposure to the solar light. Volumetric Estimation, see page 61. Examination: Fixed impurities are recognized by a residue, upon evaporation of the acid in a platinum spoon or watch-glass. Sulphueric acid may be detected in the acid, after dilution with at least five times its volume of water, by a white precipitate when tested with a few drops of barium chloride. Sulplturous acid may be detected in the filtrate of the preceding test, after the sulphuric acid, if such be present, has been completely eliminated, by mixing with it a little chlorinewater; an ensuing white turbidity would indicate sulphurous acid.* This may also be recognized or confirmed when a little of the hydrochloric acid, diluted with 4 or 5 parts of water, is poured upon pure granular zinc in a small flask (Fig. 31), and the evolved gas allowed to pass into a diluted solution of plumbic acetate in a test-tube; an ensuing black precipitate in the solution would indicate sulphurous acid; or the test may be made in a large test-tube, and the solution of plumbic acetate exposed _: to the escaping gas by closing the mouth of FIG. 81. the tube with a bunch of cotton, moistened with the solution (Fig. 29; page 72). Chlorine may be detected by the occurrence of a blue coloration, when the acid, diluted with about fiTe times its bulk of water, is mixed with a few drops of solution of potassium iodide (free of iodate) and a little mucilage of starch. Iodine and Bromine. —About eight volumes of the acid are C* hlorine and sulphurous acids, when in contact with water, form hydrochloric and sulphuric acids; therefore the presence of either one of these impurities in hydrochloric acid excludes the other one. ACIDA. 85 agitated in a test-tube with one volume of chloroform; after subsidence, the stratum of chloroform will appear red when iodine, and yellowish when bromine, is present. If the chloroform, however, remains colorless, a few drops of chlorine-water are added; when, after agitation and subsequent subsiding, the chloroform still remains colorless, the absence of hydrobromic and of hydroiodic acids is also proved. lMetals are detected in the acid, diluted with at least four times its bulk of water, when tested with hydrosulphuric acid: a white turbidity would indicate sulphurous acid or ferric chloride, a yellow one, arsenious chloride, and a dark one, metals (copper, lead, or tin); in order to distinguish the latter, the precipitate is collected upon a filter, washed, and then treated with a little warm ammonium sulphydrate; the filtrate is oversaturated with a few drops of hydrochloric acid; a brown precipitate indicates tin. The precipitate upon the filter, insoluble in ammoniumn sulphydrat,e, is washed, and dissolved in a few drops of warm nitric acid; part of this solution is oversaturated with ammoniun hydrate; a blue coloration indicates copper; another portion is diluted and tested with one or two drops of diluted sulphuric acid; a white precipitate indicates lead. Arsenic.-The presence of arsenious or arsenic chlorides may be shown by adding about 25 drops of concentrated solution of stannous chloride to about three fluid-drachms of the concentrated acid, and then adding, drop by drop, about one fluid-drachm of concentrated sulphuric acid; the mixture becomes hot, but remains clear and colorless; if, however, traces of arsenic are contained in the acid, it becomes more or less turbid, and deposits a brown precipitate. Another test is to introduce a mixture of one fluid-drachm of the acid, with four drachms of water wherein about three grains of cupric sulphate have been dissolved, into a long testtube (Fig. 32), taking care that the liquid fills only about onetenth of the tube, and that the upper interior surfaces of the tube remain dry; a few pieces of pure zinc are then added, and a small bunch of gun-cotton moistened with solution of argentic nitrate, or a cork provided with a strip of strong white blotting-paper moistened with the argentic solu 86 MANUAL OF CHEMICAL ANALYSIS. tion, is inserted into the orifice of the tube, which is then allowed to stand, protected from the solar light, for half an hour. _/'l FIG. 82, A dark coloration of the solution of argentic nitrate, not disappearing when immersed in a warm dilute solution of potassium cyanide, confirms the presence of arsenic. ACIDA. 87 T A B L E OF THE QUANTITY BY WEIGHT OF HYDROCHLORIC-ACID GAS CONTAINED IN 100 PARTS BY WEIGHT OF AQUEOUS HYDROCHLORIC ACID AT DIFFERENT DENSITIES. TEMPERATUIE 16~ C. _. Da. t.-'-~ O o I 0' 0 c 00 1.2013 41 1.1551 31.25 1.1056 21.5 1.0573 11.75 1.2002 40.75 1.1539 31 1.1044 21.25 1.0561 11.5 1.1991 40.5 1.1526 30.75 1.1031 21 1.0549 11.25 1.1980 40.25 1.1513 30.5 1.1019 20.75 1.0537 11 1.1969 40 1.1501 30.25 1.1007 20.5 1.0524 10.75 1.1958 39.75 1.1488 30 1.0994 20.25 1.0512 10.5 1.1947 39.5 1.1475 29.75 1.0982 20 1.0500 10.25 1.1936 39.25 1.1462 29.5 1.0969 19.75 1.0488 10 1.1925 39 1.1450 29.25 1.0957 19.5 1.0475 9.75 1.1913 38.75 1.1437 29 1.0945 19.25 1.0463 9.5 1.1902 38.5 1.1424 28.75. 1.0932 19 1.0451 9.25 1.1890 38.25 1.1412 28.5 1.0920 18.75 1.0439 9 1.1878 38 1.1399 28.25 1.0907 18.5 1.0427 8.75 1.1867 37.75 1.1386 28 1.0895 18.25 1.0414 8.5 1.1855 37.5 1.1373 27.75 1.0883 18 1.0402 8.25 1.1844 37.25 1.1361 27.5 1.0870 17.75 1.0390 8 1.1833 37 1.1348 27.25 1.0858 17.5 1.0378 7.75 1.1821 36.75 1.1335 27 1.0845 17.25 1.0366 7.5 1.181!0- 36.5 1.1323 26.75 1.0833 17 1.0353 7.25 1.1798 36.25 1.1310 26.5 1.0821 16.75 1.0341 7 1.1787 36 1.1297 26.25 1.0807 16.5 1.0329 6.75 1.1775 35.75 1.1284 26 1.0795 16.25 1.0317 6.5 1.1763 35.5 1.1272 25.75 1.0783 16 1.0305 6.25 1.1752 35.25 1.1259 25.5 1.0770 15.75 1.0292 6 1.1739 35 1.1246 25.25 1.0758 15.5 1.0280 5.75 1.1727 34.75 1.1234 25 1.0746 15.25 1.0268 5.5 1.1714 34.5 1.1221 24.75 1.0733 15 1.0256 5.25 1.1702 34.25 1.1208 24.5 1.0721 14.75 1.0244 5 1.1689 34 1.1196 24.25 1.0709 14.5 1.0231 4.75 1.1677 33.75 1.1183 24 1.0696 14.25 1.0219 4.5 1.1664 33.5 1.1170 23.75 1.0684 14 1.0207 4.25 1.1652 33.25 1.1157 23.5 1.0672 13.75 1.0195 4 1.1639 33 1.1145 23.25 1.0659 13.5 1.0170 3.5 1.1627 32.75 1.1132 23 1.0647 13.25 1.0146 3 1.1614 32.5 1.1119 22.75 1.0635 13 1.0122 2.5 1.1602 32.25 1.1107 22.5 1.0622 12.75 1.0097 2 1.1589 32 1.1094 22.25 1.0610 12.5 1.0073 1.5 1.1577 31.75 1.1081 22 1.0598 12.25 -1.0048 1 1.1564 31.5 1.1069 21.75 1.0585 12 1.0024 0.5 The density of the aqueous acid being decreased by an increase of temperature, and increased by a decrease of temperature, the consequent change of the specific gravity amounts for each degree of the centigrade thermometer in either directionFor acids of a specific gravity of 1.1789 to those of 1.13886 to about 0.0005 14" " " & 1.13885 " 1.0982 0.0004 L4" " " 1.0932 " 1.0635 " 0.0003 For itstance: An acid of a specific gravity of 1.1284 at 16' C. containing 25 per cent. of hydrochloric-acid gas will have at 18.5' C. a specific gravity of (1.1234-0.004 x 2.5=) 1.1224, and at 13.5~ C,. a specific gravity of (1.1234+0.004 x 2.5=) L1244. 88 MANUAL OF CHEMICAL ANALYSIS. ACIDUI BHYDROCYANICUX -DILUTUM. ACIDUM HYDROCYANATUM. Diluted Hydrocyanic Acid. Pure hydrocyanic acid is a thin, colorless, and exceedingly volatile and unstable liquid. Its odor is very powerful and characteristic, resembling that of peach-blossoms or oil of bitter almonds. It mixes with water and alcohol in all proportions. The officinal acid is a highly-dilute aqueous solution, containing only about two per cent. of anhydrous acid. It imparts a faint evanescent color to litmus, and forms a white precipitate with argentic nitrate, soluble in potassium cyanate, as well as in nitric acid, but less soluble in ammonium hydrate. Upon addition of ferric chloride to the dilute acid, and subsequent slight over-saturation with potassium hydrate, the liquid will acquire a blue color, and deposit a slight dark-blue precipitate after the addition of hydrochloric acid in excess. If a solution of mercurous nitrate is added, drop by drop, to the officinal hydrocyanic acid, a gray precipitate of metallic mercury is formed at once. Examination: Hydrochloric and phosphoric acids may be detected by shaking some of the acid with a little powdered sodium biborate; then the whole, without filtering, is evaporated in a porcelain capsule, at a gentle heat, to dryness; the residue is dissolved in dilute nitric acid, and part of the filtered solution is examined with argentic nitrate for Aydrochloric acid, which is indicated by a white precipitate. To another part of the solution ammonium molybdate is added, and heated to boiling; an ensuing yellowish precipitate indicates phosphoric acid. Forvmic acid, if present, will be detected by its property of reducing red oxide of mercury to gray metallic mercury, when a little of the acid is warmed and agitated with a few grains of the oxide. Stlphuric acid is detected by the formation of a white precipitate upon addition of a few drops of barium nitrate to the acid. ACIDA. 89 Estimation of the strength of hydrocyanie acid. There are two simple modes of ascertaining the quantity of anhydrous acid contained in hydrocyanic acid. The one depends upon the fact that one part of anhydrous hydrocyanic acid forms 5 parts of argentic cyanide; that, accordingly, 100 parts of the officinal acid should yield 10 parts of argentic cyanide. The second mode is the volumetric one, and depends upon the property of argentic cyanide to form a soluble compound with alkaline cyanides. When, therefore, the officinal hydrocyanic acid is converted into sodium or potassium cyanide by addition of sodium or potassium hydrate, no permanent precipitate will appear, upon the addition of nitrate of silver, until more than sufficient cyanide of silver is produced to form the soluble compound. 1. One hundred grains of - the acid are completely pre-: - cipitated by a solution of ar- _'- - - gentic nitrate. Then two fil- F1. 83. ters of exactly the same size and paper are cut; through the one the liquid is. filtered, the precipitate washed, and then both the empty filter and the one containing the argentic cyanide are dried, at a heat not exceeding 100~ C. When the weight of the latter filter remains constant, both filters are weighed, the empty one serving as a counterpoise of the one containing the precipitate; the excess of weight of the latter is argentic cyanide, of which10 grains represent 2.015 per cent. anhydrous hydrocyanic acid. 10.5 " " 2.10'" " " G 11 "6 2.20 " " 6 90 MANUAL OF CHEMICAL ANALYSIS. II. Twenty-seven grammes of the diluted hydrocyanic acid are converted into sodium cyanide, by adding solution of sodium hydrate until, after stirring, litmus-paper shows that the liquid has a slightly alkaline reaction. The test-solution of argentic nitrate is then allowed to flow in gradually (Fig. 33), until, after agitation, a slight permanent turbidity remains. When this occurs, the quantity of argentic nitrate added represents exactly half the amount of hydrocyanic acid present in the diluted acid, and the quantity of acid indicated denotes, therefore, when doubled, the correct percentage. For volumetric estimation, see also page 62. ACIDUM LACTICUM. Lactic Acid. A limpid, odorless, syrupy liquid, colorless, or of a pale-yellowish tint, of a sour taste, and of from 1.21 to 1.24 spec. grav. (containing 75 per cent. of hydrated lactic acid). It is miscible, in all proportions, with water, glycerin, alcohol, and ether, and also, without being colored, with concentrated sulphuric acid. Lactic acid dissolves zinc and iron, with effervescence, and cannot be distilled without undergoing partial decomposition. Heated upon platinum-foil, it emits inflammable vapors, which burn with a bright flame, and leaves a charred residue, which is completely dissipated at red heat. When heated with solution of potassium permanganate, lactic acid emits the odor of alcdehyde. One drachm of lactic acid requires for saturation not less than fifty grains of potassium bicarbonate. Examination: Gum, Ma]nnite, and Glucose.-A few drops of the acid are diluted with water in a test-tube, and slightly over-saturated with sodium carbonate; to the clear liquid are added a few drops of Fehling's solution, and the whole is gently warmed; a blue coagulation, upon the addition of the cupric solution before warming, would indicate the presence of gum; a brick-colored precipitate, after heating, indicates glucose. ACIDA. 91 The presence of gum and mannite may also be recognized by the occurrence of a turbidity upon dropping the acid into a mixture of equal parts of alcohol and ether. Glycerin may be detected by mixing, in a porcelain capsule, about 20 drops of the acid with 10 grains of oxide of zinc, previously triturated with a little water; the whole is then evaporated, upon a water-bath, to dryness; the residue is treated with strong alcohol, and the obtained alcoholic solution is evaporated upon a watch-glass; a neutral, syrupy, sweet residue would indicate glycerin. Organic Acids.-Two drops of the lactic acid are added in a test-tube to so much lime-water that the alkaline reaction remains prevalent; if a turbidity takes place at once, oxalic, tartaric, or phosphoric acid is indicated; if the turbidity does not ensue before the liquid is heated to boiling, citric acid is indicated. Acetic and butyric acids are recognized by their respective odors when the acid is gently heated in a porcelain capsule. Su lphuric, hydrochloric, and phosphoric acids may be detected in the diluted aqueous solution of the acid by testing it, in separate portions, with barium chloride for the former, and with argentic nitrate for the two latter. Acid calciumnphosphates would be indicated by a white turbidity of the dilute solution of the acid when tested with ammonium oxalate. fetals are detected in the acid, when neutralized with aqua ammonioe, and then tested with hydrosulphuric acid; a white turbidity would indicate zinc, a brown or black precipitate, copper or lead. ACIDUX NITRICUl. Nitric Acid. Nitric acid, in its most concentrated form, is a colorless, fuming, corrosive liquid, having the spec. grav. of 1.517 at 15.5~ C., and boiling at 84.50 C.; it consists of 54 parts (93 per cent.) of nitrogen pentoxide and 9 parts of water. 92 MANUAL OF CHEMICAL ANALYSIS. The crude commercial nitric acid is of two strengths: the so-called double acid has a spec. grav. of 1.36, containing about 50 per cent. of nitrogen pentoxide; and the single acid, of 1.22 spec. grav., containing about 30 per cent, of nitrogen pentoxide. The officinal nitric acid has the spec. grav. of 1.420, and contains about 60 per cent. of nitrogen pentoxide, corresponding to about 70 per cent. of monohydrated nitric acid. The Acidum nitricum dilutum, of 1.068 spec. gravity, contains 11.66 per cent. of monohydrated acid. Nitric acid is readily decomposed, and is a powerful oxidizing agent, acting violently upon most of the metals, and upon organic compounds, converting many non-nitrogenous vegetable substances into explosive bodies. From its tendency to decompose, nitric acid has frequently a yellowish color from nitrous and nitric oxides, held in solution, which, upon dilution of the acid with water, or upon heating, cause a further decomiposition and consequent disengagement of nitric peroxide. Nitric acid may. also be recognized by its property of dissolving copper-turnings to a blue solution, with the evolution of colorless nitric-oxide gas, which, however, at once unites with atmospheric oxygen, forming red fumes of nitric peroxide; by the ready decoloration of diluted solution of indigo; by its coloring pine-wood bright yellow; and by deep red or brown compounds with ferrous salts. The salts of nitric acid are remarkable for being all soluble in water. The characteristic reaction of nitric acid with ferrous salts extends also to the nitrates, when previously acted upon by strong sulphuric acid. The test is performed either by placing a crystal of ferrous sulphate in the liquid under examination, mixed with concentrated sulphuric acid, or by mixing the liquid with a concentrated solution of ferrous sulphate, and pouring this mixture carefully upon concentrated sulphuric acid in a test-tube, or by pouring it into a conical cylinder and placing concentrated sulphuric acid below it by means of a pipette (Fig. 34), so as to form in either case two supernatant layers. If a large quantity of nitric acid is present, the surfaces of the crystal, or the line of contact between the liquids, become ACIDA. 93 black; if but a small quantity is present, they become reddishbrown or purple. Volumetric.Estimation, see page 61. Examination: lydrochloric acid may be detected in the acid diluted with about five times its volume of water, by the formation of a white precipitate, when tested with argentic nitrate. StulpPAuriC acid is detected in the diluted acid by a white precipitate, when the diluted acid is tested with barium nitrate. Nitrous and Ayponitric acids are detected in the diluted acid, by one or two drops of a very dilute (1:1000) solution of potassium permanganate: their presence is indicated by decoloration. Iodine and Iodic Acid.- FIG. 34. About one drachm of the acid (the most concentrated acid has to be diluted with an equal volume of water) is shaken in a test-tube with about one-half its bulk of chloroform, which, after subsiding, will appear yellowish or reddish, if free iodine be contained in the acid; when it remains colorless, a little hydrosulphuric acid is added, drop by drop, with gentle agitation; if a coloration of the chloroform takes place now, iodic acid is indicated. A confirmatory test is, to mix the acid, after dilution, if strong acid is under examination, with a few drops of mucilage of starch; a bluish coloration will take place after a while, when iodine is present; if no reaction occurs, a few drops of solution of sulphurous acid may be added, drop byS drop, when the blue color will appear, if iodic acid be present.,.Metals may be detected by mixing the diluted acid with an equal bulk of hydrosulphuric acid, and by subsequent over-saturation with aqua ammonia. 94 MANUAL OF CHEMICAL ANALYSIS. T A BLE OF THE QUANTITY BY WEIGHT OF ANHYDROUS AND OF MONOHYDRATED NITRIC ACID CONTAINED IN 100 PARTS BY WEIGHT OF AQUEOUS NITRIC ACID AT DIFFERENT DENSITIES. (TEMPERATURE 17.5~ C.) Specific Percent. Percent. of Specific Percent. Percent. of Specific Percent. Percent. of Gravity. of NO. N05+H20 Gravity, of N0. N05 + H20 Gravity. of N5. N05 + H20 1.523 85 99.16 1.414 58.5 68.25 1.232 32 37.33 1.521 84.5 98.58 1.412 58 67.66 1.228 31.5 36.75 1.519 84 98.00 1.409 57.5 67.08 1.224 31 36.16 1.517 83.5 97.41 1.406 57 66.50 1.220 30.5 35.58 1.516 83 96.83 1.403 56.5 65.91 1.217 30 35.00 1.514 82.5 96.24 1.400 56 65.33 1.213 29.5 34.41 1.512 82 95.66 1.397 55.5 64.75 1.209 29 33.83 1.510 81.5 95.08 1.394 55 64.16 1.205 28.5 33.25 1.508 81 94.50 1.392 54.5 63.58 1.201 28 32.66 1.506 80.5 93.91 1.389 54 63.00 1.198 27.5 32.08 1.504 80 93.33 1.386 53.5 62.41 1.194 27 31.50 1.502 79.5 92.74 1.383 53 61.83 1.190 26.5 30.91 1.500 79 92.16 1.380 52.5 61.25 1.186 26 30.33 1.498 78.5 91.58 1.377 52 60.66 1.182 25.5 29.74 1.496 78 91.00 1.374 51.5 60.08 1.178 25 29.16 1.494 77.5 90.41 1.371 51 59.50 1.174 24.5 28.58 1.492 77 89.83 1.368 50.5 58.91 1.170 24 28.00 1.490 76.5 89.24 1.364 50 58.833 1.167 23.5 27.41 1.488 76 88.66 1.361 49.5 57.75 1.163 23 26.83 1.486 75.5 88.08 1.358 49 57.16 1.159 22.5 26.25 1.484 75 87.50 1.355 48.5 56.58 1.155 22 25.66 1.482 74.5 86.91 1.352 48 56.00 1.151 21.5 25.08 1.480 74 86.33 1.349 47.5 55.41 1.147 21 24.49 1.478 73.5 85.74 1.345 47 54.83 1.143 20.5 23.91 1.476 73 85.16 1.342 46.5 54.25 1.140 20 23.33 1.474 72.5 84.58 1.338 46 53.66 1.136 19.5 22.74 1.472 72 84.00 1.334 45.5 53.08 1.132 19 22.16 1.470 71.5 83.41 1.330 45 52.50 1.129 18.5 21.58 1.469 71 82.83 1.327 44.5 51.91 1.125 18 21.00 1.467 70.5 82.24 1.323 44 51.33 1.122 17.5 20.41 1.465 70 81.66 1.319 43.5 50.75 1.118 17 19.83 1.462 69.5 81.08 1.315 43 50.16 1.114 16.5 19.25 1.460 69 80.50 1.312 42.5 49.58 1.111 16 18.66 1.458 68.5 79.91 1.308 42 49.00 1.107 15.5 18.08 1.456 68 79.33 1.304 41.5 48.41 1.10.4 15 17.50 1.454 67.5 78.75 1.301 41 47.83 1.100 14.5 16.91 1.451 67 78.16 1.297 40.5 47.25 1.096 14 16.33 1.449 66.5 77.58 1.294 40 46.66 1.092 13.5 15.74 1.447 66 77.00 1.290 39.5 46:08 1.089 13 15.16 1.444 65.5 76.41 1.287 39 45.50 -1.086 12.5 14.58 1.442 65 75.83 1.283 38.5 44.91 1.082 12 14.00 1.440 64.5 75.25 1.279 38 44.33 1.078 11.5 13.41 1.438 64 74.66 1.275 37.5 43.75 1.075 11 12.83 1.436 63.5 74.08 1.271 37 43.16 1.071 10.5 12.25 1.434 63 73.50 1.267 36.5 42.58 1.068 10 11.66 1.432 62.5 72.91 1.263 36 42.00 1.064 9.5 11.07 1.430 62 72.33 1.259 35.5 41.41 1.060 9 10.50 1.428 61.5 71.75 1.255 35 40.83 1.056 8.5 9.91 1.426 61 71.16 1.251 34.5 40.25 1.053 8 9.33 1.424 60.5 70.58 1.247 34 39.66 1.050 7.5 8.84 1.422 60 70.00 1.243 33.5 39.08 1.045 7 8.16 1.419 59.5 69.41 1.239 33 38.50 1.038 6 7.00 1.417 59 68.83 1.236 32.5 37.91 1.032 5 5.83 ACIDA. 95 With the decrease and increase of temperature, the density of nitric acid suffers a corresponding increase or decrease, amounting for each degree of the centigrade thermometer in either directionFor acids of a specific gravity of 1.492 to those of 1.476 to 0.00213 in the average. "s s" "1 I.4T2 " 1.456 " 0.002 1.454 " 1.434 " 0.00186 1.430 " 1.412 "0.0011 " " 1.406 " 1.383 " 0.00155 " " " 1.377 " 1.352 " 0.00141 " " 1.845 " 1.315 " 0.00128 1.308 "f 1.279 "0.00114 t" " " 1.271 " 1.239 " 0.001 " " 1.232 " 1.201 " 0.00085 " " " 1.194 " 1.163'0.00071 " " " " " 1155 " 1.125 "0.0005 "'; For instance: An acid of 1.178 spec. grav. at 17.5~ C. containing 25 per cent. of anhydrous, or 29.16 per cent. of monohydrated, nitric acid will have, at 20~ C., a spec. grav. of (1.178-0.00072x2.5=) 1.762, and at 15~ C. a spec. grav. of (1.178+0.00072 x 2.5=)1.1798. ACIDUI OXALICU1M. Oxalic Acid. Colorless, transparent, oblique-rhombic prisms, containing 2 molecules (28 per cent.) of water of crystallization, which they lose in a dry and'varm air, the crystals crumbling down to a soft white powder of anhydrous oxalic acid, which may be sublimed, in a great measure, without decomposition. Heated upon platinum-foil, the crystals first fuse, with slight crepitation, and finally are completely dissipated, emitting inflammable fumes. Oxalic acid is soluble in 8 parts of cold water, and in its own weight, or less, of boiling water; it is also soluble in 7 parts of glycerin, and in about 4 parts of alcohol, but sparingly in ether and chloroform. Its solution has a very sour taste, and a strong acid reaction; it forms with the alkaline metals soluble, with all other bases, for the most part, insoluble, salts, which, however, are soluble in dilute acids. When a cold saturated aqueous solution of oxalic acid is dropped into strong alcohol, it should not produce a turbidity; when dropped into lime-water, a copious white precipitate 96 MANUAL OF CHEMICAL ANALYSIS. must ensue at once, which remains unchanged upon addition of acetic acid, as well as of ammonium chloride, but which is readily dissolved by hydrochloric and nitric acids. Added to a solution of calcium sulphate, a precipitate is also produced after a while. When heated with concentrated sulphuric acid, oxalic acid is resolved into water and equal volumes of carbonic oxide and carbonic acid, without being charred. Examination: Binoxalates and qtadroxalates of potassium (sorrel and lemon salts) are detected by heating about half a drachm of the oxalic acid in a platinum or porcelain capsule, to redness, and until no more fumes are emitted; a white fused residue, turning red litmus-paper blue, and effervescing with a few drops of hydrochloric acid, would indicate potassium or traces of calcium. Crude commercial acid mostly leaves a very small trace of residue, too insignificant, however, to impair the quality of the acid, or render it unfit for its common technical applications. Tartaric, citric, and racemic acids. and their salts, as accidental admixtures in oxalic acid, may be detected by gently heating, in a test-tube, some of the crystals in strong sulphuric acid. The crystals, as well as the acid, must not become darkcolored or blackened, otherwise the presence of the one or other of such admixtures is indicated. ACIDUIYI PTHOSPHORICUM. Phosphoric Acid. Glacial, monobasic, or metaphosphoric acid forms colorless, transparent, glass-like, fusible masses, deliqltescent, and slowly but freely soluble in water and in alcohol, yielding colorless, inodorous acid solutions. The fused acid consists of 142 parts of metaphosphoric acid and 18 parts of water, containing, therefore, 11.2 per cent. of water. Its aqueous solution produces white monobasic precipitates with albumen and with sol. uble salts of silver, barium, and calcium. When its solution is ACIDA. 97 heated for some time, the m9nobasic acid is converted into the tri-basic acid, which is contained in the medicinal acidurn phosphoricurn dilutuin. This process is accelerated by the addition of a little nitric acid to the boiling solution of the monobasic acid. Acidumn phosphoricurm diluttum forms a colorless, inodorous, acid fluid of 1.056 spec. grav., containing 7.2 per cent. of anhydrous tri-basic phosphoric acid, 100 grains of which saturate 23.4 grains of crystallized potassium bicarbonate, without precipitation. This acid does not coagulate albumen nor precipitate barium chloride; when neutralized with sodium carbonate, it yields a light-yellow precipitate with argentic nitrate, soluble in nitric acid and in ammonium hydrate. It produces, in dilute solution of ammoniated magnesium sulphate, a white crystalline precipitate of ammonio-magnesium phosphate, which, when collected and washed upon a filter, becomes yellow upon being moistened with dilute solution of argentic nitrate. Examination of Glacial Phosphoric Acid: Ammoniuzm may be detected by heating a few fragments of the fused acid in a strong solution of potassium hydrate in a test-tube; the odor of ammonium hydrate and the formation of white fumes, when a glass rod, moistened with acetic acid. is held over the orifice of the tube, will indicate ammonium. For further examination, about two drachms of the glacial acid are dissolved in six fluid-drachms of water, in a small porcelain capsule; when dissolved, 20 drops of concentrated nitric acid are added, and the fluid boiled until reduced to about half its original bulk; then so much water is added as to make the fluid measure one ounce. I iagnesiumn and aluminiuznz are detected in a small portion of this acid, after dilution with water, by the formation of a white precipitate upon over-saturation with strong ammonium hydrate; if this is soluble in acetic acid, magnesium is indicated; if it is insoluble or only partly soluble, aluminium is also indicated, and may be confirmed by heating a little of it on platinum wire before the blow-pipe; the colorless bead will assume a blue color, after-being moistened with solution of cobaltous nitrate, and reheated, when aluminium is present. Calcizum and Silicic Acid. —Another part of the above solu 98 MANUAL OF CHEMICAL ANALYSIS. tion of the acid is mixed with about four times its volume of absolute alcohol; if a precipitate is formed, it is collected upon a filter, and, after the alcoholic liquid has passed through the filter, is treated with liquor potassme; if a residue remains on the filter, the presence of calcium is indicated; if the precipitate, however, be partly or entirely dissolved, the solution is oversaturated with hydrochloric acid and evaporated to dryness at a gentle heat; the residue is dissolved in water acidulated with sulphuric acid; if a white turbid solution results, silicic acid is indicated. lfetals.-The rest of the solution of the acid may be examined for metals in the same mode as described under acidum phosphoricurm dilutum. Examination of Acidum Phosphoricuan Dilutum: Monobasic phosphoric acid may be detected by the formation of a gelatinous white precipitate when tested with solution of albumen. Phosphorozs acid is indicated, if no arsenious acid be present, by decoloration when a little of the acid is heated in a test-tube, with one or two drops of potassium permanganate. It may also be detected in the diluted acid by adding a few drops of solution of mercuric chloride, and gently warming the liquid; an ensuing white turbidity would confirm the presence of phospliorous acid. Hycdrochloric acid is detected by a white precipitate with argentic nitrate in the diluted acid, to which previously have been added a few drops of concentrated nitric acid. N~itric acid is indicated by decoloration when a little of the acid is gently heated with one drop of indigo-solution. Its presence may be confirmed by mixing with the acid nearly an equal bulk of concentrated solution of ferrous sulphate, and by placing this mixture upon concentrated sulphuric acid, with the precaution that the two fluids do not mix (Fig. 35); a redbrown coloration upon the line of contact between the two fluids will confirm the presence of nitric acid. Sulphueric acid is detected in the diluted acid, to which a few drops of nitric acid have been added, by a white precipitate with barium nitrate. Nietals are detected by saturating the diluted acid with hy ACIDA. 99 drosulphuric-acid gas, and allowing the liquid to stand for 12 hours in a corked test-tube or flask; the occurrence of a coloration or precipitate will indicate metals; a light-yellow floccuFIG. 85. lent one, arsenic; a brown or black one, copper, lead, or tin. They may be discriminated by the methods described on page 41. Arsenious as well as arsenic acids may be detected in phosphoric acid by the two following equally accurate methods: 1. A mixture of about two drachms of the officinal phosphoric acid with two drachins of concentrated pure hydrochloric acid and about 20 drops of concentrated solution of stannous chloride, is heated in a test-tube; the mixture, at first white and turbid, becomes transparent and clear; a brown coloration or turbidity will indicate arsenic. 2. Three fluid-drachms of the phosphoric acid are warmed in a test-tube; then one drop of solution of potassium permanganate is added; if decoloration takes place, the solution is added drop by drop until decoloration of the reagent ceases; one fluid-drachm of concentrated sulphuric acid (previo'uslyr tested for arsenic) is added, and the mixture placed in a long 100 MANUAL OF CHEMICAL ANALYSIS. test-tube (Fig. 36), care. being taken that the interior upper parts of the tube remain dry; a few pieces of pure zinc are'I.: F IG. -' 36 FIG. 86. then added, and the test conducted in the mode described on page 30. A dark coloration of the solution bf argentic nitrate will confirm the presence of arsenic, ACIDA. 101 TAB:LE OF THE QUANTITY BY WEIGHT OF ANHYDROUS AND OF TRI-HYDRATED PHOSPHORIC ACID CONTAINED IN 100 PARTS BY WEIGHT OF AQUEOUS PHOSPHORIC ACID AT DIFFERENT DENSITIES. TEMPERATURE 1T.5~ C. Specific Percent. Percent. of Specific Percent. Percent. of Specific Percent. Percent. of Gravity. of PO5. PO +31120 Gravity. of P06. PO +3H20 Gravity. of PO5. P0 + 3H20 1.809 68 93.67 1.462 46 63.37 1.208 24 33.06 1.800 67.5 92.99 1.455 45.5 62.68 1.203 23.5 32.37 1.792 67 92.30 1.448 45 61.99 1.198 23 31.68 1.783 66.5 91.61 1.441 44.5 61.30 1.193 22.5 30.99 1.775 66 90.92 1.435 4: 60.61 1.188 22 30.31 1.766 65.5 90.23 1.428 43.5 59.92 1.183 21.5 29.62 1.758 65 89.54 1.422 43 59.23 1.178 21 28.93 1.750 64.5 88.85 1.415 42.5 58.55 1.174 20.5 28.24 1.741 64 88.16 1.409 42 57.86 1.169 20 27.55 1.733 63.5 87.48 1.402 41.5 57.17 1.164 19.5 26.86 1.725 63 86.79 1.396 41 56.48 1.159 19 26.17 1.717 62.5 86.10 1.389 40.5 55.79 1.155 18.5 25.48 1.709 62 85.41 1.383 40 55.10 1.150 18 24.80 1.701 61.5 84.72 1.377 39.5 54.41 1 1.145 17.5 24.11 1.693 61 84.03 1.371 39 53.72 1.140 17 23.42 1.685 60.5 83.34 1.365 38.5 53.04 1.135 16.5 22.73 1.677 60 82.65 1.359 38 52.35 1.130 16 22.04 1.669 59.5 81.97 1.354 37.5 51.66 1.126 15.5 21.35 1.661 59 81.28 1.348 37 50.97 1.122 15 20.66 1.653 58.5 80.59 1.342 36.5 50.28 1.118 14.5 19.97 1.645 58 79.90 1.336 36 49.59 1.113 14 19.28 1.637 57.5 79.21 1.330 35.5 48.90 1.109 13.5 18.60. 1.629 57 78.52 1.325 35 48.21 1.104 13 17.91 1.621 56.5 77.83 1.319 34.5 47.52 1.100 12.5 17.22 1.613 56 77.14 1.314 34 46.84 1.096 12 16.53 1.605 55.5 76.45 1.308 33.5 46.15 1.091 11.5 15.84 1.597 55 75.77 1.303 33' 45.46 1.087 11 15.15 1.589 54.5 75.08 1.298 32.5 44.77 1.083 10.5 14.46 1.581 54 74.39 1.292 32 44.08 1.079 10 13.77 1.574 53.5 73.70 1.287 31.5 43.39 - 1.074 9.5 13.09 1.566 53 73.01 1.281 31 42.70 1.070 9 12.40 1.559 52.5 72.32 1.276 30.5 42.01 1.066 8.5 11.71 1.551 52 71.63 1.271 30 41.33 1.062 8 11.02 1.543 51.5 70.94 1.265 29.5 40.64 1/.058 7.5 10.33 1.536 51 70.26 1.260 29 39.95 1.053 7 9.64 1.528 50.5 69.57 1.255 28.5 39.26 1.049 - 6.5 8.95 1.521 50 68.88 1.249 28 38.57 1.045 6 8.26 1.513 49.5 68.19 1.244 27.5 37.88 1.041 5.5 7.57 1.505 49 67.50 1.239 -27 37.19 1.037 5 6.89 1.4-98 48.5 66.81 1.233 26.5 36.50 1.033 4.5 6.20 1.491. 48 66.12 1.228 26 35.82 1.029 4 5.51 1.484 47.5 65.43 1.223 25.5 35.13 1.025 3.5 4.82 1.476 47 64.75 1.218 25 34.44 1.021 3 4.13 1.469 46.5 64.0.6 1.213 24.5 33.75 1.017 2.5 3.44 102 MANUAL OF CHEMICAL ANALYSIS. With the decrease or increase of temperature, the density of phosphoric acid suffers a corresponding increase or decrease, amounting for each degree of the centigrade thermometer in either directionFor acids of a specific gravity of 1.809 to those of 1.618 to about 0.001. 1.597 " 1.462 " 0.00082. 1 " ".448 " 1.336 " 0.00068. " 1.325 " 1.228 " 0.00052. 1.218 " 1.122 " 0.0004. 1.113 1.079 " 0.00035. For instance: An acid of 1.130 spec. grav. at 17.5~ C., containing 16 per cent. of anhydrous or 22.04 per cent. of tri-hydrated phosphoric acid, will have, at 20~ C., a spec. grav. of (1.130-0.0004 x 2.5=) 1.129, and at 150 C., a spec. grav. of (1.130+0.0004 x 2.5=) 1.131. ACIDUT SUCCINICUM. Succinic Acid. Colorless, oblique-rhombic prisms, without odor when pure, and with a more or less strong odor when the acid is obtained from amber by sublimation, and is only imperfectly freed from the empyreumatic oils. When heated upon platinum-foil, it fuses at 180~ C., and emits irritating fumes, leaving a charred residue, which, however, is entirely dissipated upon heating to red heat. Pure succinic acid dissolves in from 25 to 28 parts of cold, and about three parts of boiling, water, in 15 parts of cold, and in 1i part of boiling, alcohol; it is but' sparingly soluble in ether and in oil of turpentine (distinction from benzoic acid); its aqueous solution yields, when neutralized with aqua ammonise, a copious reddish-brown precipitate with diluted solutions of ferric salts, which is re-dissolved upon addition of hydrochloric acid. Examination: Fixed Admixtures.-If a residue remains when the acid is heated and dissipated upon platinum-foil, about two drachms of it are completely incinerated in a porcelain crucible; the residue, when cold, is tested with moist turmeric as well as with red, litmus-paper; it is then divided into three parts; one of ACIDA. 103 which is mixed with a little strong alcohol, and this ignited; a green color of the flame, especially toward the termination of the ignition, indicates boracic acid; another portion of tlhe residue is moistened with one drop of concentrated hydrochloric acid; effervescence would indicate potassium bitartrate, or other tartrates, citrates, or oxalates; the third portion is dissolved in a few drops of water and one drop of nitric acid, and tested with barium nitrate; a white precipitate would indicate potassium sul-phate or bislphate. Ammonin, salts are detected by the odor of ammonia and by white fumes when a glass rod, moistened with acetic acid, is held in the test-tube, when the acid is heated in solution of potassium hydrate..Metallic imn}prities may be detected in the concentrated solution of the acid, by the admixture of an equal volume of hydrosulphuric acid. Organic acids and salts may be detected by agitating four grains of the succinic acid in two drachms of hot water; a complete solution must take place, and continue after cooling; when a white precipitate separates on cooling, it is collected upon a filter, washed with a few drops of cold water, and, when perfectly dry, treated with a few drops of warm oil of turpentine, wherein it will dissolve, if it is benzoic acid. A portion of the aqueous solution of the acid is then dropped into strong alcohol; an ensuing turbidity would indicate mineral salts; another part of the solution is dropped into lime-water, taking care that this, with its alkaline reaction, remains prevalent; the formation of a white turbidity would indicate oxalic or tartaric acids, or their salts; if a turbidity is not formed until after warming the liquid, citric acid or citrates would be indicated; a little solution of ammonium chloride is added and agitated: oxalate will remain unaltered, tartrate or citrate will partly or entirely dissolve. The followingr may serve as a general test for the purity of succinic acid: Ten grains of the acid are dissolved in 3 fluiddrachms of strong or absolute alcohol; the solution is aided by dipping the test-tube in hot water; when cold, it is divided into two parts, one of which is mixed with an equal bulk of chloroform, the other with an equal bulk of aqua ammonie; 104 MANUAL OF CHEMICAL ANALYSIS. a complete solution must take place in the first test, and a clear mixture in the second, otherwise one or more of the above-mentioned adulterations are present. When a crude acid, containing empyreumatic substances, has to be examined, it is first agitated and washed with a little ether, and is then dissolved in boiling water, and the solution, when cold, passed through a filter previously moistened with water. ACIDUM SULPHURICUM. Sulphuric Acid. A dense, colorless, inodorous, highly-corrosive liquid, of a spec. grav. of from 1.843 to 1.850, containing from 18 to 20 per cent. of water, and 96.8 per cent. of monohydrated sulphuric icid. At this density one fluidounce of the acid weighs a small fraction over 14 drachms. It has a strong attraction for water, absorbing it from the atmosphere, and withdrawing it or its elements from organic compounds immersed in, or inxed with, the acid; sulphuric acid, therefore, when in contact with organic substances, or with air containing dust, gradually loses its colorless appearance, and becomes more or less brown, and rapidly chars and destroys most organic substances. Sulphuric acid is miscible with water, glycerin, alcohol, chloroform, carbon bisulphide, and other solvents, with evolution of heat, and produces, with most organic liquids, a more or less vehement decomposition; in its relations to other compounds, it maintains the character of one of the strongest acids, its affinity for bases being so powerful as to withdraw them from most of their compounds, forming sul)hates, which, with the exception of those of barium, strontium, lead, and calcium, are soluble in water. By the same powerful affinity, sulphuric acid decomposes water, and deprives it of its oxygen, when in contact with water and certain metals (iroh, zinc, tin, magnesium), or part of the acid itself is decomposed by the abstraction of oxygen, with the forma ACIDA. 105 tion of metallic oxides and of sulphates, when concentrated sulphuric acid acts upon some metals (copper, mercury, silver). A piece of pine-wood, dipped into concentrated sulphuric acid, will become black, and when a piece of loaf-sugar is placed in a little of the acid, in a test-tube, and gently heated, the acid will become black, and emit the odor of sulphurous acid; when one drop of the acid is mixed with a test-tubeful of water, this will let fall a white precipitate upon the addition of a few drops of barium chloride. Volumetric Estimnal;ioz, see page 61. FIG. 37. FIG. 38. Examination: Fixed imnpurities are recognized by a residue after complete evaporation of a few drops of the acid upon platinum-tbil. Lead is indicated by a white turbidity taking place upon the careful admixture of one part of the acid with about four or five times its volume of alcohol (Fig. 37). Another method of readily recognizing the presence of lead -in sulphuric acid is, to fill a small conical cylinder about half with concentrated hydrochloric acid, and then to place below the acid, by means of a pipette, a nearly equal volume of the sulphuric acid, with care that the fluids do not mix (Fig. 38); an ensuing white turbidity at the junction of the two fluids would confirm the presence of lead. 106 MANUAL OF CHEMICAL ANALYSIS. The presence of lead and other metallic impurities may be also detected by nearly neutralizing the acid, diluted with two or three times its bulk of water, with aqua ammonioe or liquor potassm, and by adding, while yet warm, an equal volume of.o. FIG. 89. hydrosulphuric acid, and allowing the liquid to stand for several hours; a precipitate would indicate lead or other metals, which, when required, may he further examined by the methods described in the course of analytical investigation (page 41). ACIDA. 1 07 Arsenic may be detected by either of the two following methods: 1. About half a fluidounce of a mixture of equal parts, by volume, of the concentrated sulphuric acid and water is, when cool, heated in a test-tube, and a solution of potassium permanganate added drop by drop, until lecoloration ceases; then about 20 grains of sodium chloride, and subsequently 20 drops of concentrated solution of stannous chloride, are added, and the mixture heated. An ensuing brown turbidity would indicate arsenic. 2. To about one fluid-drachm of the sulphuric acid are added one or two drops of solution of potassium permanganate, or, if decoloration takes place, enough to make this cease. The acid is then added to 4 parts, by volume, of water, and introduced into a long test-tube, of which it should fill not more than about one-tenth, and whose interior above the fluid should remain dry (Fig. 39); a few pieces of pure zinc are then added, and the test performed in the mode described on page 30. 8ulphlurous acid and oxides of nitrogen are indicated by decoloration upon the addition of one drop of sulphuric-acid indigo-solution, and gentle warming, as also by decoloration of solution of potassium permanganate. A special test for nitrogen oxides consists in dissolving two or three drops of pure anilin in about one drachmn of diluted sulphuric acid, and in adding gradually, with gentle stirring with a glass rod, about twice the volume of the concentrated sulplhuric acid (Fig. 37). Nitrogen oxides, if present, cause rose-colored lines in the track of the glass rod. 108 MANUAL OF CHEMICAL ANALYSIS. T OF A YDROUS AND OF MONO-YDRATED OF THE QUANTITY BY WEIGHT OF ANHYDPROUS AND OF MONO-HlYDRITED SULPHURIC ACID CONTAINED IN 100 PARTS BY WEIGHT OF AQUEOUS SULPHURIC ACIDS AT DIFFERENT DENSITIES. TEMPEPRATURE 17.5' C. Speciflc Percent. Specific Percent. Specific Percent. o0 Gravity. of SO3. V + Gravity. of SO3. ~ + Gravity. of SO,. ~ + 1.841 81.6 100 1.559 53.8 66 1.235 26.1 32 1.840 80.8 99 1.547 53.0 65 1.257 25.3 31 1.839 80.0 98 1.536 52.2 64 1.219 24.5 30 1.838 79.2 97 1.525 51.4 63 1.211 23.6 29 1.837 78.3 96 1.514 50.6 62 1.202 22.8 28 1.835 77.5 95 1.503 49.8 61 1.194 22.0 27 1.833 76.7 94 1.493 49.0 60 1.186 21.2 26 1.830 75.9 93 1.482 48.1 59 1.178 20.4 25 1.826 75.1 92 1.471 47.3 58 1.170 19.6 24'1.821 74.3 91 1.461 46.5 57 1.163 18.7 23 1.815 73.4 90 1.450 45.7 56 1.155 17.9 22 1.808 72.6 89 1.440 44.9 55 1.147 17.1 21 1.800 71.8 88 1.430 44.0 54 1.140 16.3 20 1.791 71.0 87 1.420 43.2 53 1.132 15.5 19 1.782 70.1 86 1.411 42.4 52 1.125 14.7 18 1.774 69.4 85 1.401 41.6 51 1.117 13.8 17 1.765 68.5 84 1.392 40.8 50 1.110 13.0 16 1.755 67.7 83 1.382 40.0 49 1.103 12.2 15 1.744 66.9 82 1.373 39.2 48 1.095 11.4 14 1.733 66.1 81 1.364 38.3 47 1.088 10.6 13 1.722 65.3 80 1.354 37.5 46 1.081 9.8 12 1.711 64.4 79 1.345 36.7 45 1.074 9.0 11 1.699 63.6 78 1.336 35.9 44 1.067 8.1 10 1.688 62.8 77 1.328 35.1 43 1.060 7.3 9 1.676 62.0 76 1.319 34.3 -42 1.053 6.5 8 1.665 61.2 75 1.310 33.4 41 1.046 5.7 7 1.653 60.4 74 1.302 32.6 40 1.039 4.9 6 1.641 59.6. 73 1.293 31.8 39 1.032 4.1'5 1.629 58.7 72 1.285 31.0 38 1.025 3.2 4 1.617 57.9 71 1.276 30.2 37 1.019 2.4 3 1.605 57.1 70 1.268 29.4 36 1.012 1.6 2 1.593 56.3 69 1.260 28.5 35 1.006 0.8 1 1.582 55.5 68 1.251 27.7 34 1.003 0.4 0.5 1.570 54.7 67 1.243 26.9 33 0.0000 0 0 With the decrease and increase of temperature, the density of sulphuric acid suffers a corresponding increase or decrease, amounting for each degree of the centigrade thermometer in either directionFor acids of a specific gravity of 1.841 to those of 1.782 to about 0.0014. 4t" " " 4 1.774 " 1.665 " 0.0012. 64" " " 1.653 " 1.302 " 0.001. L4" " " 1.293 " 1.219 " 0.000T5. " " " 1.211 " 1.140 " 0.00045. " " " 1.182 " 1.067 " 0.0004T. ACIDA. 109 ACIDUM TANNICUM. Tannic Acid. Tannin. Amorphous, friable, porous, and inodorous masses, or thin shining seales, of a pale greenish-yellow color, and feeble, mild odors (mostly combined with a faint odor of ether); when heated upon platinum-foil, tannic acid fuses, swells up, and burns awav without residue. Tannic acid is soluble in about two parts of water, in three parts of glycerin, and in less than its own weight of diluted alcohol; but it is less soluble in strong alcohol. only sparingly in ether, and insoluble in the fixed and volatile oils: its aqueous solution reddens litmus-paper, and has an astringent taste without bitterness; it becomes turbid when boiled, and gradually dark-colored and mouldy, when exposed to the air; it suffers precipitation by the alkaline salts, and by the mineral acids, and forms soluble compounds with the alkaline hydrates, sparingly soluble ones with the earthy oxides, and more or less insoluble ones with most of the metallic oxides; its solution coagulates solutions of gluten, albumen, and starch (distinction from gallic acid), and affords white precipitates, soluble in acetic acid, with the alkaloids; it renders no reaction with ferrous salts, if completely free from ferric salts, but it gives a bluish-black precipitate with the latter, which is soluble in oxalic and mineral acids. When solution of tannic acid is dropped into lime-water, it produces a white turbidity, which soon becomes gray and dingy green, and passes through various shades to a dark purple-brown color. Examination: The absence of admixtures of iesinous suzstasances, of dextrin, and of sugar, may be ascertained by the property of the acid to yield a clear or almost clear solution with about four or five parts of warm water, which should remain so when tested in two portions, the one by addition of twice its volume of strong alcohol, the other by dilution with water; if any such adulterations be present, they may be separated and recognized by making two solutions of the acid, one in strong alcohol * The color and odor are due to traces of a greenish resin. 110 MANUAL OF CHEMICAL ANALYSIS. when sugar and dextrin will remain behind, and another one in boiling water, when resinous substances will be expelled on cooling. ACIDUM TARTARICUM. Tartaric Acid. Colorless, transparent crystals, which have the form of an oblique rhombic prism, more or less modified; they are permanent in the air; but when heated, they fuse, become black, and are decomposed and charred, with the evolution of inflammable vapors of a peculiar odor, and are finally wholly dissipated without residue. Tartaric acid is soluble in an equal weight of cold, and half its weight of boiling, water, and in three parts of alcohol, forming solutions of a strongly acid taste and reaction, which, when dropped into solutions of neutral potassium salts, give rise to the formation of a white granular precipitate, at once in concentrated solutions, and after a time in diluted ones. This reaction, however, does not take place in solutions containing free mineral acids or acid salts thereof. When solution of tartaric acid is dropped into lime-water, so that the alkaline reaction remains prevalent, a white turbidity occurs (distinction from citric acid) which, disappears again upon addition of solution of ammonium chloride (distinction from racemic acid), and also upon addition of acetic acid (distinction fromn oxalic acid); solution of calcium sulphate remains unchanged upon addition of tartaric acid (additional distinction from oxalic and racemic acids). Crystals of tartaric acid, when immersed in concentrated sulphuric acid, dissolve gradually without coloration, unless warmed, when they become black. One drachm of tartaric acid requires, for saturation, 65.70 grains of potassium carbonate, 79.98 grains of crystallized potassium bicarbonate, 114.39 grains of crystallized sodium carbonate, 67.20 grains of sodium bicarbonate, and 38.19 grains of magnesium carbonate. Volumetric Estimation, see page 61. ACIDA. 111 Examination: Salts.-An admixture of salts is recognized by an addition of an equal volume of alcohol to a cold saturated aqueous solution of the acid, or by dissolving the powdered acid in 6 parts of strong alcohol; a complete solution must take place and remain in either case. Szulphates may be detected in the diluted solution, by a white turbidity with barium nitrate. Oxalates may be detected in the concentrated aqueous solution of the acid, by a white precipitate when tested with solution of calcium sulphate. Calcium salts may be detected in the diluted solution, neutralized with aqua amnmonie, by a white precipitate with ammonium oxalate. _Metallic impurities (copper or lead) are detected when a saturated aqueous solution of the acid is mixed with about twice its bulk of hydrosulphuric acid. ACIDUM VALERIANICUM. Vcalerianic Acid. Pure valerianic acid forms a thin, colorless, or nearly colorless liquid, having the persistent odor of valerian-root and a pungent, acid taste; it reddens litmus, bleaches the skin, and burns with a bright, smoky light. In contact with water, it absorbs about 20 per cent. of its weight without losing its oily consistence, and is itself soluble in about 26 parts of water; it is mliscible with aqua ammoniae, alcohol, and ether, in all proportions. Its spec. grav. is from 0.935 to 0.940, and it boils at 175~ C. The commercial acid is generally trihydrated, having a density of' 0.950, and the boiling-point at 1650 C. Examination: Fatly Acids.-Twenty grains of the acid are weighed in a tared flask, and water, of a temperature of from 12~ to 15~ C., is carefully added, with constant agitation, until the acid is just dissolved. The bottle is weighed again, and the quantity of 112 MANUAL OF CHEMICAL ANALYSIS. water required for solution must be not less than 26 times the weight of the acid; in this instance, not less than one ounce and two scruples. If the acid dissolves in less water, it is not pure, containing admixtures (alcohol, acetic acid, and but yric acid), which by their greater solubility increase that of the valerianic acid. On the other hand, the quantity of water required for solution must not exceed thirty times (10 drachms) the weight of the valerianic acid, in which case it would contain less soluble or insoluble admixtures (caproic and similar monatomic acids, valerie aldehyde, etc.). If the preceding test leaves doubt as to the purity of the acid, or if a more conclusive examination be required, one drachm of the acid is weighed in a beakerglass, and mixed with two draehms.....!X a of hot water; then from a burette, or a graduated pipette (Fig. 40), a solution of potassium carbonate, of 1.33 spee. grav. (containing 33- per cent. of anhydrous carbonate), is added drop by drop, until the acid is exactly neutralized. The quantity by weight of the solution of potassium carbonate used must very little, if at all, exceed twice the quantity of the acid; if a greater quantity be required, the presence of bntyric, acetic, and similar homologous acids, is evident. When, in this test, oily F~I. 40. drops are separated upon the surface of the liqjuid, the admixture of some neutral oily compound is indicated. Acetic acid may be detected, by adding to the liquid obtained in the preceding test half as much hydrochloric acid, of 1.124 spec. grav. (containing 25 per cent. of anhydrous acid), as was required of the potassium-carbonate solution for saturation; after agitation, the liquid is transferred upon a small glass funnel, provided with a stop-cock. After the separation ACONITIA. 113 of the supernatant fatty acid, the lower aqueous layer is drawn off through the stop-cock. A part of this solution is carefully neutralized, in a test-tube, with diluted aqua amnmoniae, and a tfew drops of a solution of ferric perchloride are then added; a reddish-brown precipitate will ensue, which, upon agitation, acquires a resinous appearance; the supernatant liquid must appear colorless; a reddish color would indicate acetic acid..Mineral acids may be detected in the aqueous solution of the valerianic acid by adding a few drops of nitric acid, and by subsequently testing portions of it with barium nitrate for sulphuric acid, and with argentic nitrate for hydrochloric. ACONITIA. ACONITIN UM. Aconitia. Aconitine. White, amorphous, pulverulert grains, or a white or yellowish-white powder, or colorless rhombic or six-sided prisms, fusing, when heated upon platinum-foil, at about 80~ C., without loss of weight; at about 120~ C. it becomes brown, and, at a higher temperature, burns away without a residue. Aconitia is but sparingly soluble in cold water; with hot water it becomes soft and resin-like, and dissolves gradually,: in the proportion of one part of aconitia to 50 parts of hot water; upon cooling, most of the aconitia separates again. The aqueous solution has a persistent bitter and acrid taste, and a feeble alkaline reaction; upon addition of concentrated sulphuric acid, the solution remains unchanged, or becomes slightly yellow; but, when heated by immersing the test-tube in boiling water, it turns purple, and, upon the addition of potassium bichromate, green. Alcohol, ether, chloroform, carbon bisulphide, benzol, and diluted acids, dissolve aconitia freely; its solution in water, acidulated with hydrochloric or sulphuric acids, yields a white precipitate with solutions of tannic acid, of phosphoric acid, of potassio-mercuric iodide, and of the alkaline hydrates and 8 114 MANUAL OF CHEMICAL ANALYSIS. carbonates, a brown one with solution of iodinized potassium iodide. Aconitia dissolves in concentrated nitric acid without change; with concentrated sulphuric acid, it forms a coherent mass, which dissolves upon agitation, with a yellowish-brown color, gradually changing to purple or brown. It is also dissolved by phosphoric acid; this solution becomes purple upon evaporation on a porcelain capsule, in a water-bath. A kind of aconitia is occasionally met with in commerce which differs from that above described in its chemical and therapeutical properties, and which is evidently derived from one or more non-officinal species of Aconitum; it is readily recognized by its slighter solubility in chloroform, requiring about 230 parts for solution, while the officinal aconitia dissolves in 2~ parts of chloroform. JETHER. Ether. Ethyliec Ether. Ethyl Oxide. A colorless, light, and limpid liquid, of a characteristic fragrant odor, very volatile and inflammable; it does not redden litmus, but becomes slightly acid by the absorption of oxygen and the formation of acetic acid, from contact with the air in imperfectly-stoppered bottles. When pure, its spec. grav., at 15.5~ C., is about 0.720. The United States Pharmacopoeia provides two strengths of ether, one of the spec. grav. of 0.750, at 15.5~ C., containing about 70 per cent., and tether fortior, of a spec. grav. not exceeding 0.728 at 15.50 C., and containing abQut 90 per cent. of ethylic ether. Ether is miscible, in all proportions, with alcohol, carbon bisulphide, chloroform, and benzol; pure ether dissolves about two per cent. of water, increasing thereby its density from 0.720 to 0.723, at 15.5~ C. Water, on the other hand, dissolves nearly 10 per cent. of ether. From its solution in ether, the water can wholly be removed again by anhydrous potassium carbon ~ETHER. 115 ate, provided that the ether be pure and free from alcohol. When completely free from alcohol and water, ether has no action on dry tannic acid, which deliquesces to a thick, syrupy fluid in aether fortior. Ether dissolves sulphur and phosphorus sparingly, but bromine, iodine, gun-cotton, caoutchouc, essential oils, and most of the fatty and resinous substances, freely; it is also a solvent for a number of alkaloids, and for some metallic salts, e. g., mercuric, auric, platinic, and ferric chlorides, etc. Examination: Alcohol and Water.-Shaken with an equal bulk of water, in a small graduated cylinder (Fig. 41), officinal ether should not lose more than from one-fifth to one-fourth, and sether fortior not more than from one-tenth to one-eighth, of its volume; otherwise an excess of one or other of the above is contained in the ether, which fact will also be indicated by a greater density of the ether than that above stated. A still more accurate result of this test is obtained when pure glycerine is employed ifistead of water. Acids.-Blue neutral litmus-paper, when immersed in both strata in the cylinder, should remain unaltered, as also when a small quantity of the ether is evaporated in a porcelain capsule until reduced to a few drops, and then tested with litmus-paper; a slight acid reaction would indicate acetic acid, and, in crude ether, possibly sulphurous or sulphuric acid; the acid reaction o may also be caused by traces of ethyl sulphate; traces of this and other ethylic or amylic ethers or alcohols are also indicated when about half an ounce of the ether is evaporated from a flat porcelain capsule by causing the fluid to flow to and fro; when the ether is evaporated, the FIG. 41. surfaces of the capsule should be covered with a deposit of moisture, without taste or smell; and without any oily appearance. 116 MANUAL OF CHEMICAL ANALYSIS. TA 13 LE OF THE QUANTITY BY WEIGHT OF PURE ETHIYLIC ETHER CONTAINEDr TI 100 PARTS BY WEIGHT OF ETHER AT DIFFERENT DENSITIES. TEMPERATURE 11.5' C. Specific; Specific: Specific g Specific P Gravity. Gravity. Gravity. Gravity. avity.;Li P_ PPo 0.7185 100 0.7310 87 0.7456 74 0.7614 61 0.7198 99. 0.7320 86 0.7468 73 0.7627 60 0.7206 98 0.7331 85 0.7480 72 0.7640 59 0.7215 97 0.7342 84 0.7492 71 0.7653 58 0.7224 96 0.7353 83 0.7504 70 0.7666 57 0.7233 95 0.7364 82 0.7516 69 0.7680 56 0.7242 94 0.7375' 81 0.7528 68 0.7693 55 0.7251 93 0.7386 80 0.7540 67 0.7707 54 0.7260 92 0.7397 79 0.7552 66 0.7721 53 0.7270 91 0.7408 78 0.7564 65 0.7735 52 0.7280 90 0.7420 77 0.7576 64 0.7750 51 0.7290 89 0.7432 76 0.7588 63 0.7764 50 0.7300 88 0.7444 75 0.7601 62 0.7778 49 With the decrease and increase of temperature, the density of ether suffers a corresponding increase or decrease, amounting for each degree of the centigrade thermometer in either directionFor ether of a specific gravity of 0.7198 to that of 0.7331, about 0.0013. 0.7342 " 0.504, " 0.0011. 0.7516 " 0.7621, " 0.0009. 0.7640 " 0.764, " 0.0008. For instance. An ether of 0.7206 spec. grav. at 17.50~., containing 98 per cent. ethyl oxide, will have, at 20~ C., a spec. grav. of (0.7206-0.0013 x2.5=) 0.7173, and, at 15~ C., a spec. grav. of (0.7206+0.0013 x2.5=) 0.7239..ETIER ACETICUS. Acetic Ether. Ethyl Acetate. A colorless, light, limpid liquid, of an agreeable, ethereal, and fruity odor and taste; very volatile and combustible. When pure, its spec. grav. is 0.900 to 0.904 at 150 C., and its AETHER. 117 boiling-point at 74 to 76~ C. Acetic ether is miscible in all proportions with ether, alcohol, chloroform, carbon bisulphide, and benzol; it is miscible with water, and soluble therein, ill approximately the same proportion as ether. It absorbs oxygen from the air, especially if it contains some water, forming acetic acid; both the water and the acid can be removed from the ether by shaking it with exsiccated potassium carbonate, which will become more or less liquefied when these fluids are present. Examination: Alcohol.-When shaken with an equal volume of water in a graduated glass cylinder (Fig. 41, page 115), the ether, after subsiding, should not have decreased in bulk more than onetenth to one-eighth; when pure glycerine is employed instead of water, the volume of both liquids should remain almost unaltered. Alcohol and water are also indicated by a greater density, and consequently a lower specific gravity of the ether. Acids. —Neutral litmus-paper, when immersed in both strata in the cylinder, should remain unaltered, as also in the remainder of a little of the ether when evaporated in a porcelain capsule. Estimation of the ethyl acetate contained in acetic ether. Fifty grains of pure crystallized barium hydrate are introduced into a 2-ounce vial, with so much water as to leave room for 20 grains of the ether; the vial is then corked and weighed, and 20 grains of acetic ether are added. The flask is then tightly closed, and allowed to stand in a warm place or in tepid water, agitating it occasionally for several hours, until the ethereal odor of the liquid has entirely ceased. The contents of the flask are then emptied into a beaker or flask, the flask being rinsed with a little water to avoid loss. Carbonic-acid gas is now passed into the liquid until this has an acid reaction; it is then warmed, the turbid liquid transferred to a filter, and the precipitate washed by means of a washing-bottle. The entire filtrate is completely precipitated with diluted sulphuric acid; the ensuing precipitate is collected upon a moistened tared filter, washed, dried, and weighed. The weight of the precipitate, divided by 1.32, gives, as a quotient, the quantity of ethyl acetate contained in 20 grains of the acetic ether, which result, multiplied by five, gives the percentage. 118 MANUAL OF CHEMICAL ANALYSIS. ALCOHOL. SPIRITUS RECTIFICATUS. Ethyl Alcohol. Alcohol absolutum, Spiritus alcoholisatus. Spec. grav., 0.795. 100 per cent. of real alcohol by volume. Alcohol fortius, Spiritus rectificatissimus. Spec. grav., 0.817. 95 per cent. of real alcohol by volume. Alcohol rectificatum, Spiritus rectificatus. Spec. grav., 0.835. 90 per cent., by volume, of real alcohol. Alcohol dilutum, Spiritus tenuinor. Spec. gray., 0.941. 46 per cent. of real alcohol by volume. A colorless, limpid, neutral liquid, inflammable, and burning with a blue flame, without smoke; its spec. grav. is 0.795 at 150 C.; its boiling-point at 78.4~ C.; it is miscible in all proportions with most liquid bodies, except the fatty oils, and, next to water, is the most extensive and important solvent; it combines with some salts, forming alcoholates. Anhydrous alcohol has a great attraction for water, absorbing its vapor from the atmosphere, and abstracting the moisture from organic substances immersed in it. In the act of dilution, a contraction of volume and an increase of the temperature of the mixture take place. When 55 volumes of absolute alcohol are mixed with 45 volumes of water, the mixture, after cooling, will occupy only 96.2 volumes, having therefore suffered a contraction of 3.8 per cent.: and, vice versa, an expansion'of volume takes place when diluted alcohol is mixed with water: e. g., when 100 volumes of alcohol, of a spec. grav. of 0.966, containing 28 per cent., by volume, of real alcohol, are mixed with 50 volumes of water, 153 volumes will be obtained. The percentage of real alcohol in its aqueous dilutions call be determined approximately, but accurately enough for any practical purpose, by ascertaining its specific gravity at a known temperature. The specific gravity -of any sample of alcohol established will, by the aid of the following table, at once indicate the percentage of real alcohol: ALCOHOL. 119 TA BLE OF THE QUANTITY OF REAL ALCOHOL CONTAINED IN 100 PARTS OF AQUEOUS ALCOHOL BY WEIGHT AND BY VOLUME AT DIFFERENT DENSITIES. TEMPERATURE 15~ C. Specific 100 Volumes 100 Parts by Specific 100 Volumes 100 Parts by Gravity. contain: Weight contain: Gravity. contain: Weight contain: Alcohol. Water. Alcohol. Alcohol. Water. Alcohol. 0.7951 100 0.00 100.00 0.9348 50 53.72 42.53 0.8000 99 1.28 98.38 0.9366 49 54.70 41.59 0.8046 98 2.54 96.83 0.9385 48 55.68 40.66 0.8089 97 3.77 95.35 0.9403 47 56.66 39.74 0.8130 96 4.97 93.89 0.9421 46 57.64 38.82 0.8169 95 6.16 92.45 0.9439 45 58.61 37.90 0.8206 94 7.32 91.08 0.9456 44 59.54 37.00 0.8242 93 8.48 89.72 0.9473 43 60.58 36.09 0.8277 92 9.62 88.37 0.9490 42 61.50 35.18 0.8311 91 10.76 87.04 0.9506 41 62.46 34.30 0.8344 90 11.88 85.74 0.9522 40 63.42 33.40 0.8377 89 13.01 84.47 0.9538 39 64.37 32.52 0.8409 88 14.12 83.22 0.9553 38 65.32 31.63 0.8440 87 15.23 81.96 0.9568 37 66.26 30.75 0.8470 86 16.32 80.72 0.9582 36 67.20 29.88 0.8500 85 17.42 79.51 0.9595 35 68.12 29.01 0.8530 84 18.52 78.29 0.9607 34 69.04 28.14 0.8559 83 19.61 77.09 0.9620 33 69.96 27.27 0.8588 82 20.68 75.91 0.9633 32 70.89 26.41 0.8616 81 21.76 74.75 0.9645 31 71.80 25.56 0.8644 80 22.82 73.59 0.9657 30 72.72 24.70 0.8671 79 23.90 72.43 0.9668 29 73.62 23.85 0.8698 78 24.96 71.30 0.9679 28 74.53 23.00 0.8725 77 26.03 70.16 0.9690 27 75.43 22.16 0.8752 76 27.09 69.04 0.9700 26 76.33 21.31 0.8778 75 28.15 67.93 0.9711 25 77.23 20.47 0.8804 74 29.20 66.82 0.9721 24 78.13 19.63 0.8830 73 30.26 65.72 0.9731 23 79.09 18.79 0.8855 72 31.30 64.64 0.9741 22 79.92 17.96 0.8880 71 32.35 63.58 0.9751 21 80.81 17.12 0.8905 70 33.39 62.50 0.9761 20 81.71 16.29 0.8930 69 34.44 61.43 0.9771 19 82.60 15.46 0.8954 68 35.47 60.38 0.9781 18 83.50 14.63 0.8978 67 36.51 59.33 0.9791 17 84.39 13.80 0.9002 66 37.54 58.29 0.9801 16 85.29 12.98 0.9026 65 38.58 57.25 0.9812 15 86.19 12.15 0.9049 64 39.60 56.23 0.9822 14 87.09 11.33 0.9072 63 40.63 55.21 0.9833 13 88.00 10.51 0.9095 62 41.65 54.20 0.9844 12 88.90 9.69 0.9117 61 42.67 53.19 0.9855 11 89.80 8.87 0.9139 60 43.68 52.20 0.9867 10 90.72 8.06 0.9161 59 44.70 51.20 0.9878 9 91.62 7.24 0.9183 58 45.72 50.21 0.9890 8 92.54 6.43 0.9205 57 46.73 49.24 0.9902 7 93.45 5.62 0.9226 56 47.73 48.26 0.9915 6 94.38 4.81 0.9247 55 48.74 47.29 0.9928 5 95.30 4.00 0.9267 54 49.74 46.33 0.9942 4 96.24 3.20 0.9288 53 50.74 45.37 0.9956 3 97.17 2.40 0.9308 52 51.74 44.41 0.9970 2 98.11 1.60 0.9328 51 52.73 43.47 0.9985 1 99.05 0.80...~~~~ 120 MANUAL OF CHEMICAL ANALYSIS. Since, however, the temperature exercises a considerable expanding and contracting influence upon alcohol and its dilution with water, it is necessary to ascertain, simultaneously with the specific gravity, also the temperature of the sample; for this reason, the areomneters (Alcoholometers) constructed for measuring the density of alcohol are provided with a thermometer, and differences in the temperature of the alcohol under estimation may readily be corrected by calculation based upon this rule: The number of degrees of temperature of the alcohol above or below 15~ must be multiplied by four-tenths; the product is then to be added to the percentage of the real alcohol indicated by the specific gravity, when the sample was cooler than 15~ C., and subtracted, when it was warmer. If, e. g., the spec. grav. of a sample is found to be 0.860, at a temperature of 50~., its percentage of real alcohol would be, according to the above table, 81 per cent., by volume; since, however, the alcohol was weighed at a temperature 10~ lower than the standard temperature of the above table, its density was accordingly greater. Therefore, in order to correct this difference, 10 has to be multiplied by four-tenths; the product (= 4) must be added to the percentage of alcohol (81) inferred from the spec. grav., and the sum (= 85) expresses the real quantity of alcohol in 100 parts by volume. Examination: Fusel-oil (a mixture of ethyl and amyl alcohols, containing traces of propylic, butylic, and other alcohols) and aldehyde may be detected by mixing about half an ounce of the alcohol with an equal volume of pure ether, and by subsequently adding an amount of water equal to the volume of the mixture; the whole is shaken, and, when subsidence has taken place, the ethereal layer is decanted and evaporated at the common, or at a slightly-raised, temperature. After the evaporation of the ether, the remainder will give the characteristic odor of fusel oil, or of any flavors indicative of a previous employment of the alcohol for the extractidn of vegetable substances. 72lethyl Alcool. —Among the several methods for the detection of methylic alcohol as an admixture in ethyl alcohol, the following is least open to objection: Thirty grains of powdered potassium bichromate are dissolved, in a little flask, in half an ounce of water; 25 drops of concentrated sulphuric acid, and ALCOHOL. 12t subsequently 40 drops of the alcohol under examination, are added, and the flask closed with a cork provided with a delivery-tube, leading into a large test-tube, cooled in ice-water (Fig. 42). After allowing the mnixture to stand for about a quarter of an hour, the flask is gently warmed until about half a fluidounce of distillate is obtained; the distillate is then slightly over-saturated with a little crystallized sodium carbonate, and evaporated to the bulk of about one-quarter of an ounce; when cool, it is filtered into a small test-tube, and then slightly overS I. _ _ _ _ _!!__'_ _!_ _l_ _ Iiil ill l, l'l it Iti _ FIG. 42. saturated with a few drops of acetic acid; 20 drops of solution of argentic nitrate (1:20) are then added, and the mixture gently heated for a few minutes. If the liquid merely darkens a little, but continues quite translucent, the alcohol is free from methylic alcohol; but, if a dark-brown or black precipitate of reduced silver separates, and the test-tube, after being rinsed and filled with water, shows upon its interior a brilliant metallie resplendence, which, when seen against white paper, appears brown by transmitted light, the alcohol is imethylated. 122 MANUAL OF CHEMICAL ANALYSIS. ALCOHOL ADYLICUX. Amylic Alcohol. Fusel-Oil. A colorless or pale-yellow, mobile, oily liquid, of a strong, offensive odor, and acrid, burning taste; its spec. grayv. is 0.818 and its boiling-point between 132~ and 133~ C.; it solidifies at about -22~ C. When dropped upon water, it floats upon the surface like an oil. Fusel-oil requires about 40 parts of water for solution; it is miscible, in all proportions, with alcohol, ether, carbon bisulphide, chloroform, and essential and fatty oils; it dissolves iodine, sulphur, phosphorus, camphor, and resins. Three parts of amylic alcohol mixed with two parts of concentrated sulphuric acid, form a purple mixture, firom which the alcohol separates unaltered upon dilution with water; when the mixture, however, has been allowed to stand for several hours, amyl-sulphuric acid is formel, which is soluble in water. When a mixture of amylic alcohol with strong sulphuric acid is heated with a fragment of potassium bichromate, the odor of valerianic acid is evolved. Amylic alcohol does not take fire by contact with a flame, and, when dropped on paper, does not leave a permanent greasy stain. ALUXEN. ALUMINII ET POTASSII SULPHAS. ALUMINII ET AMMONII SULPHAS. Alum. Colorless, transparent, octahedral crystals, which often exhibit the faces of a cube, permanent in the air; when exposed to heat, they undergo aqueous fusion at about 100~ C., and, at a stronger heat, lose their water of crystallization, and swell up to a white porous mass, which, when moistened with a few drops of solution of cobaltous nitrate and reheated, assumes a blue color. Alum is soluble in 25.3 parts of water at 0~ C., and in about 15 parts of cold, and in its own weight of boiling, water; it is ALUMINIUM. 123 also soluble in glycerin, but insoluble in alcohol, ether, and chloroform. Its solution has a sweetish, astringent taste, reddens litmus-paper, and gives a bulky white precipitate with the alkaline hydrates, of which that with potassium or sodium hydrate is soluble in an excess of the reagent, but it is reprecipitated by ammonium chloride; the alkaline carbonates and phosphates, and solutions of barium salts, also throw down white precipitates. Most commercial alum is a mixture of ammonium and potassium alum, the former being substituted, to a greater or less extent, for the latter; since their properties are almost the same, this admixture is of little consequence in the common uses of alum. Potassium alum consists, in 100 parts, of 18.39 parts of potassium sulphate, 36.14 parts of aluminium sulphate, and 45.47 parts of water of crystallization; while ammonium alumt contains, in 100 parts, 14.58 of ammonium sulphate, 37.83 of aluminium sulphate, and 47.59 of water of crystallization. The presence of ammonium alum is recognized by the odor of ammonia, and by its reaction upon moistened red testpaper, and with a glass rod moistened with acetic acid, when a little of the powdered alum is heated in liquor potassse. Examination: Iron is recognized in the solution of alum, after the addition of a few drops of sulphuric acid, by a blue coloration when tested with potassium ferrocyanide: most crude alum contains traces of ferric salts; their quantity, however, should not be so considerable as to produce a purple coloration of a solution of the alum upon the addition of a few drops of solution of tannic acid. Other metallic impurities may be detected in the solution, after addition of a little tartaric acid and subsequent over-saturation with liquor potassse, by ammonium sulphydrate; a dark coloration or precipitate indicates metallic impuiities; a white precipitate, not disappearing upon addition of potassium hydrate, would show zinc. If required, the nature of such precipitate may be determined by the method described on pageb 41 to 43. 124 MANUAL OF CHEMICAL ANALYSIS. ALUMINII SULPHAS. ALUMINIUM SULPHURICUM. Aluminium Sulphate. A white crystalline powder, or small pearly plates, of a soursweet and astringent taste, permanent in the air; when exposed to heat the salt fuses, loses at first the water of crystallization, and, at a strong heat, the sulphuric acid also, leaving behind aluminium oxide (alumina or argilla), which, when moistened with solution of cobaltous nitrate and reheated, assumes a blue color. Aluminium sulphate is soluble in twice its weight of cold water, forming a clear solution, of an acid reaction and astringent taste, which affords a bulky white precipitate with the alkaline hydrates, of which that with the fixed hydrates is soluble in an excess of the precipitant (evidence of the absence of magnesium), but'is precipitated again upon addition of ammonium chloride. The alkaline solution should yield no reaction upon the addition of a few drops of ammonium sulphydrate; the occurrence of a brown or vellowish-red precipitate would indicate ferric and manganic salts, and of a white one, zinc. AXIONII B3ENZOAS. AMMONIUM B ENZOICU M. Benzoate of Ammonium. Ammonium Benzoate. Small, colorless, shining, thin, four-sided, tabular crystals, deliquescent in the air, and having a feeble odor of benzoic acid, and a saline, somewhat balsamic, and bitterish taste. When heated, the salt sublimes without residue. It is soluble in water, glycerin, and alcohol; its aqueous solution, if not too dilute, emits the odor of ammonia when heated with potassium hydrate, and gives a white precipitate of benzoic acid upon addition of hydrochloric acid, and a copious, pale, reddish-yellow precipitate with ferric salts. The diluted solution of ammonium benzoate must remain clear when mixed with lime-water (evidence of the absence of ammonium oxalate). AMMONIUM. 125 AMIVLONII BROXIDUX. AMMONIUM BROMATUM. Bromide of Ammonium. Ammonium Bromide. Colorless, transparent, anhydrous crystals, or a granular salt, which, by the action of the atmospheric oxygen, gradually becomes yellow; entirely volatile by heat, and subliming unchanged. Ammonium bromide is soluble in 1~1 part of cold water, in about 15 parts of alcohol, and but sparingly in ether. Its solution has a saline, pungent taste, is neutral, and, when dropped into a dilute solution of argentic nitrate, acidulated with a few drops of nitric acid, gives a white, curdy precipitate, soluble upon addition of aqua ammonite; when dropped into a very dilute solution of mercuric chloride, no reaction takes place (distinction from alkaline iodides). When the aqueous solution is mixed with a little mucilage of starch, and afterward with a little chlorine-water, a yellowish coloration takes place, which will transfer its color to chloroform, ether, or carbon bisulphide, when added and agitated with the solution. A blue tint upon the addition of the chlorine-water, and a violet or reddish coloration of the chloroform, would indicate iodides. Heated with potassium hydrate, it emits the odor of ammonia. Examination: Amnmoniumn bromale is detected in the aqueous solution by an ensuing red coloration upon the addition of concentrated hydrochloric acid. Arnmonium chloride, as an admixture, may approximately be ascertained bycompletely precipitating a solution of 10 grains of the dry crystallized salt in one ounce of water, acidulated with nitric acid, by a solution of argentic nitrate; the precipitate is collected upon a moist double filter, both being of equal size, is washed, dried, and, when completely dry, weighed, the one filter serving to counterpoise the other one, which contains the precipitate; if the salt was pure ammonium bromide, the obtained argentic bromide must weigh 19.15'grains; if it contained alkaline chloride, the weight will be greater in proportion to the quantity of the latter. 126 MANUAL OF CHEMICAL ANALYSIS. AMDIONII CARBONAS. AMMONIUM CARBONICUM. Carbonate of Ammonium. Ammonium Sesqui-carbonate. Colorless, hard, translucent, crystalline masses, of a strong ammoniacal odor, completely volatile, without fusion, when heated; exposed to the air, the salt decomposes rapidly, giving off water and ammnoniunl hydrate, and is converted into a white, opaque, pulverulent mass of ammonium bicarbonate, which requires eight parts of cold water for solution, while the sesqui-carbonate dissolves in four parts of water. Ammonium sesqui-carbonate is soluble in about five parts of glycerin; it is but sparingly soluble in alcohol, and dissolves in acids with effervescence; one drachm of the salt requires for saturation 71.16 grains of citric, and 76.26 grains of tartaric, acid. Volumetric Estimation, see page 58. Examination: Ammonium bicarbonate is already indicated by the change of the hard crystalline state of the salt into the soft one; it is further recognized by agitating one drachmn of the triturated salt with from five to six drachms of cold water; in this case, pure sesqui-carbonate renders a clear solution, while the bicarbonate will not dissolve until two or three more drachms of water have been added. Ammonrium sulgphate is detected in the aqueous solution, over-saturated with nitric acid, by a white precipitate with barium nitrate. A.nmmonium chloride and hyposulphite are recognized in the aqueous solution, over-saturated with acetic acid, by testing it with argentic nitrate; a white precipitate, insoluble in diluted nitric acid, will indicate chloride; a white turbidity, which gradually turns black, indicates hyposulphite. Zletcas are detected in the aqueous solution, over-saturated with nitric acid, by hydrosulphuric acid. AMMONIUM. 127 AdCMONII CHLORIDUM. AMMONII MURIAS. AMMONIUM CHLORATUM. SAL AMMONIACUM. Ammonium Chloride. A colorless anhydrous salt, either in translucent, crystalline masses, of a tough fibrous texture, or in small cubic or octahedral crystals, or a granular white powder. When heated, the salt volatilizes without fusion or decomposition, and condenses, upon cooling, in thick white fumes; it yields a white and soft streak when scratched with a knife; and remains white, and evolves the odor of ammonia, when moistened with liquor potassae. Ammonium chloride is soluble in three parts of cold, and in its own weight of boiling, water, and in about six parts of glycerin, but only sparingly in alcohol, and not at all in ether or chloroform; its aqueous solution has a sharp, saline taste, reddens blue litmus-paper, emits the odor of ammonia when heated with liquor potassm, and forms a copious, curdy, white precipitate with argentic nitrate. Examination: Sulphates are detected in the diluted solution by a white precipitate, when tested with barium nitrate. Fixed impurities are indicated by a residue left after complete volatilization of the ammonium chloride, upon platinumfoil or in a porcelain crucible..Metallic impurities may be detected in the aqueous solution by a coloration or precipitate when tested with hydrosulphuric acid, and by subsequent addition of aqua amInonim; if a precipitate be formed with the first reagent, it is collected upon a filter, after several hours' digestion, and the filtrate is then rendered alkaline with ammonium hydrate; if a second precipitate be then formed, it is also collected. The first precipitate may contain tin, copper, and zinc; the second one, iron and manganese; if required, they may be discriminated by the methods described on pages 41 to 43. Iron may also be recognized at once by a blue coloration, when the solution of the salt is acidulated with hydrochloric acid, and tested with potassium ferrocyanide. 128 MANUAL OF CHEMICAL ANALYSIS. AMIIONII IODIDUM. AMMONIUM IODATUM. Iodide of Ammonium. Ammonium Iodide. A white; granular, crystalline salt, which, when exposed to the air, becomes yellowish or reddish brown, from oxidation and consequent liberation of a minute quantity of iodine. When heated, it is completely volatilized with the evolution of purple vapors. Ammonium iodide is very soluble in water, and freely soluble in alcohol (distinction from ammonium and potassium bromides, which are less soluble in alcohol); its solution has a pungent, saline taste, and emits the odor of ammonia when heated with liquor potasse; it yields a red precipitate with mercuric bichloride, and a yello:wish-white one with argentic nitrate, which latter precipitate remains unchanged upon the addition of dilute nitric acid and of aqua ammonioe; the solution assumes a blue color upon the addition of mucilage of starch and a little chlorine-water. Examination: An admixture of alkaline iodides, bromides, or chlorides, is approximately recognized, when a concentrated aqueous solution of the salt is dropped into strong alcohol; the liquid must remain clear; the separation of a white crystalline powder would indicate such an admixture. Chiorides and bromindes are detected by completely precipitating the solution of the salt with argentic nitrate, and by subsequent addition of aqua ammonia; the filtrate is then oversaturated with nitric acid; a slight turbidity may take place; a white precipitate would indicate chlorides and bromides. In this case, and in order to distinguish argentic chloride or bromide, the precipitate is collected and washed-upon a filter, and is then rinsed through the pierced filter into a test-tube; the supernatant water is decanted as far as practicable, and good chlorine-water is poured upon and agitated with the silver salt. This will remain unchanged if it consists of argentic chloride, but, if it contains argentic bromide, the chlorine-water assumes a yellowish or reddish color, which will also be absorbed by chloroform, when agitated with the liquid. AMMONIUM. 129 Sul.phate may be detected in the diluted solution, acidulated with tartaric acid, by a white precipitate upon the addition of a few drops of barium nitrate. AMXIONII NITRAS. AMMONIUM NITRICU-I. Nitrate of Ammonium. Ammonium Nitrate. Long, flexible needles, or a fibrous crystalline mass, when obtained by crystallization above 40~ C.,:and large six-sided prisms, terminated by six-sided pyramids, when crystallized at a temperature below 38~ C.; they contain four molecules of water of crystallization, which evaporates slowly at common temperatures. Exposed to the air, ammonium nitrate deliquesces slightly, loses ammonium hydrate, and becomes acid; it fuses at 108~ C., commences boiling at 180~ C., and between 2100 and 240~ C. it is resolved and entirely volatilized into watery vapor and nitrous-oxide gas. When heated rapidly, ammonium hydrate, nitric oxide, and ammonium nitrite, are also formed; when thrown upon a red-hot surface, it burns with a slight noise and a pale-yellow flame; in contact with heated combustible matter, it deflagrates, like all nitrates. Ammonium nitrate dissolves in about half its weight of cold water, producing considerable depression of temperature; it is also soluble in twice its weight of alcohol, so that its concentrated aqueous solution remains perfectly limpid upon addition of strong alcohol. Its aqueous solution emits the odor of ammonium hydrate, when heated with liquor potassoe; and when mixed with a few drops of a solution of ferrous sulphate, and carefully poured upon concentrated sulphuric acid,-it affords a dark zone at the junction of the liquids, characteristic of the oxides of nitrogen. Examination: Ammonium chloride and sulphate may be detected by white precipitates, when the dilute aqueous solution of the salt is acidulated with nitric acid and tested in separate portions, with 9 130 MANUAL OF CHEMICAL ANALYSIS. argentic nitrate for the former salt, and with barium nitrate for the latter. AMMONII PHOSPHAS. AMMONIUM PHOSPHORICUM. Phosphate of Ammonium. Tri-basic Ammonium Phosphate. Transparent, colorless prisms, efflorescent in the air; when heated upon platinum-foil, ammonium hydrate, and subsequently thick, white vapors of phosphoric acid, are evolved, and the salt is wholly dissipated at a red heat. When treated with liquor potassoe, ammonium hydrate is given off. Ammonium phosphate is readily and freely soluble in water, but insoluble in alcohol; its solution is slightly alkaline, but, when the salt has been exposed to the air or is old, the solution is neutral, or even acid, from the loss of ammonium hydrate; this reaction, with the formation of an acidulous ammonium phosphate, takes place when the alkaline solution of the salt is boiled. With solution of argentic nitrate, the diluted solution of ammonium phosphate gives a yellow precipitate, soluble upon addition of ammonium hydrate, as well as of nitric acid. It must give no reaction with ammonium sulphydrate, and, after acidulation with diluted hydrochloric acid, none with hydrosulphuric acid or with barium chloride. A precipitate with the first two reagents would indicate metals, a white precipitate with the latter reagent, insoluble in diluted nitric acid, would indicate sulphate. If a solution of twenty grains of ammonium phosphate is completely precipitated with solution of ammoniated magnesium sulphate, and the precipitate collected and washed upon a filter with diluted aqua ammonia, dried, and subsequently heated to redness in a tared porcelain crucible, the residue obtained must weigh 16.8 grains. ANTIMONIUM. 131 AMMONII VALERIANAS. AMMONIUM VALERIANICUM. Falerianate of Ammonium. Ammonium Valerianate. Colorless, transparent, quadrangular plates, or a white, translucent, crystalline mass, with the odor of valerianic acid. When heated, the salt melts and emits vapors of the odor of ammonium hydrate and of valerianic acid; at a stronger heat it becomes black, with the evolution of pungent, inflammable vapors, and is at last wholly dissipated. It is decomposed, and emits the odor of ammonium hydrate, when heated in liquor potassse. Ammonium valerianate is deliquescent in moist air, and is freely soluble in water, glycerin, and alcohol; its aqueous solution, if not very dilute, separates, upon super-saturation with acids, an oily layer of valerianic acid. The underlying aqueous liquid, when nearly saturated with aqua amlnonioe, must not become red upon the addition of one drop of dilute solution of ferric chloride, for in this case acetic acid (admixture of potassium or sodium acetate) would be indicated, which may also be recognized by a fixed residue upon complete dissipation of the salt upon platinum-foil, which residue will effervesce when moistened with one drop of concentrated hydrochloric acid. AN.TIMONII ET POTASSII TARTRAS. ANTIMONIUM TARTARATUM. ANTIMONIUM ET POTASSIUM TARTARICUM. TARTARUS STIBIATUS. Tartar Emetic. Pota Qsio-antimonious Tartrate. Colorless, transparent, triangular-faced crystals, or a white powder. The crystals contain one molecule (2.7 per cent.) of water of crystallization; they effloresce slightly when exposed to the air, and lose their water of crystallization completely at 1100 C., becoming white and opaque; when heated, they decrepitate and blacken; when powdered and heated in a dry 132 MANUAL OF CHEMICAL ANALYSIS. test-tube, tartar emetic emits sour empyreumatic vapors, and leaves a charred residue which, when cool, turns moist turmericpaper brown; when the residue is placed upon charcoal and heated before the blow-pipe, white fumes are evolved, coating the coal, and brittle globules of antimony are formed. Tartar emetic dissolves in about 15 parts of cold, and 2 to I2I parts of boiling, water; it is almost insoluble in alcohol. Its solution has a nauseous metallic taste, a slightly acid reaction upon blue litmus-paper, and gradually decomposes if not containing a small addition of alcohol; it is decomposed both by acids (except acetic, tartaric, and citric acids) and by alkaline hydrates; an excess of the latter redissolves the precipitate; it is also precipitated by all soluble carbonates, but not by bicarbonates. Hydrosulphuric acid produces an orange-red coloration in concentrated solutions of tartar emetic, and gradually a precipitate of the same color; in very dilute solutions, only a coloration takes place; but, upon warming, or upon the addition of an acid, or when the tartar emetic is contaminated with potassium bitartrate, a turbidity ensues immediately. Solution of tartar emetic reduces a solution of mercuric chloride to mercurous chloride, gradually at common temperatures, and quickly at elevated ones. Examination: Arsenic is indicated by the garlic-like odor when about 10 grains of the powdered tartar emetic are charred in an iron spoon, or in a porcelain crucible, and subsequently heated to redness. If the result of this test be doubtful, or confirmatory evidence be required, about 10 grains of the finely-powdered tartar emetic are dissolved in a test-tube in about three fluiddrachms of concentrated hydrochloric acid, to which from 30 to 50 drops of water have been added; then a few pieces of tinfoil (real tin), or, if this be not at hand, about 25 drops of concentrated solution of stannous chloride, are added to the solution, and this heated to boiling; the liquid must remain clear and colorless on cooling; a brown turbidity or precipitate would indicate arsenwc. Chlorides and sulphates may be detected in the aqueous solution of tartar emetic, to which a little tartaric acid has ANTIMONIUM. 133 been added, by testing it in separate portions, with argentic nitrate for the former, and barium nitrate for the latter. A white precipitate in either instance would indicate the respective impurity. Potass8ium Bitcartrate.-Ain admixture of this salt may be approximately recognized by the difference of the solubility of tartar emetic (1.15) and of cream of tartar (1.184) in cold water; when, therefore, one part of the tartar emetic is agitated with 16 to 18 parts of warm water (27 grains of the former in one ounce of the latter), a complete solution must take place, and remain unchanged after cooling. If cream of tartar be present, it will separate in small crystals. The absence of any admixture of potassium bitartrate or other salts may be established either by completely precipitating an aqueous solution of 20 grains of tartar emetic with hybdrosulphuric-acid gas, whereby a precipitate is obtained which, when collected, washed, and completely dried upon a tared filter, must weigh 9.91'grains; or by volumetric estimation of a solution of one gramme of tartar emetic in 30 grammes of water, to which have been added 5 grammes of a saturated solution of potassium bicarbonate, and subsequently a little mucilage of starch. To this solution, test-solution =i of iodine is added from a bu- i- By rette (Fig. 43), with constant FIG. 43. gentle agitation of the liquid, until this just acquires a fixed blue tint. The quantity of iodine required, multiplied by 1.315, gives as product the quan 134 MANUAL OF CHEMICAL ANALYSIS. tity of potassio-antimonious tartrate contained in one gramme of the tartar emetic. If the tartar emetic was pure, 60 centimetres of the test-solution must have been required for the reaction. ANTIMONII OXIDUI. ANTIMONIUM SEU STIBIUM OXYDATUM. Oxide of Antimony. Antimonious Oxide. A grayish-white or pale-buff powder, when obtained by precipitation; or small, colorless, transparent, brilliant needles, when obtained by sublimation (Flores Antimonii). When heated, antimonious oxide becomes yellow, and fuses at a dullred heat, forming a yellowish liquid, which solidifies, on cooling, into a crystalline mass of a pearl color; at a stronger heat, it volatilizes in white vapors; when mixed and hleated with exsiccated sodium carbonate on charcoal before the blow-pipe, antimonious oxide is reduced, forming globules of metallic antimony which are brittle when cold. Antimonious oxide is insoluble in water and in aqua ammoniee, sparingly soluble in nitric and in acetic acid, but readily soluble in warm hydrochloric acid, in warm liquor potassce or sodoe, and in solutions of tartaric acid, and the alkaline tartrates. Its acid solutions afford an orange-red precipitate with hydrosulphuric acid; its solutions in the fixed alkaline hydrates are not acted upon by this reagent (distinction from alkaline solutions of salts of lead and zinc), but, with argentic nitrate, a black precipitate is formed, insoluble upon addition of ammonium hydrate. Examination: Antimronic oxide would be indicated by a turbidity on dissolving the oxide in warm hydrochloric acid. Antimonious oxy-chiloride (Algaroth's Powder) is indicated by a white precipitate, when a diluted solution of the oxide in an excess of tartaric acid is tested with argentic nitrate; its presence may be confirmed by digesting a little of the oxide for ANTIMONIUM. 135 about one hour with a dilute solution of sodium carbonate, and by testing the subsequent filtrate, after over-saturation with nitric acid, with argentic nitrate. Arsenic is recognized by the garlic-like odor, when a little of the oxide is mixed and subsequently fused and reduced upon charcoal before the blow-pipe. Its presence may be confirmed by dissolving about 10 grains of the oxide in about 3 fluiddrachms of concentrated hydrochloric acid, and by heating the solution either with a small piece of real tin-foil, or with about 20 drops of a concentrated solution of stannous chloride. A brown turbidity would indicate arsenic. ANTIMONII OXY-SULPHURETUM. ANTIMONIUM OXY-SULPHURATUM. STIBIUM SULPHURATUM RUBEUM. Mineral Kermes. Sulphurated Antimony. Antimonious Oxy-sul2phide. An insipid powder of a dark brick-red color, becoming gradually lighter by the action of air and light. It is a mixture of antimonious sulphide with a small and variable amount of antimonious oxide, the former appearing under the microscope in amorphous globules, or laininte, and the latter in small, colorless crystals, or fragments of such.. When heated upon charcoal before the blow-pipe, mineral kermes fuses and burns away, with the evolution of white fumes, and the odor of sulphurous acid; heated with the addition of a little dried sodium carbonate, brittle globules of antimony are obtained. Antimnonious oxy-sulphide is insoluble in water and alcohol, but readily and wholly soluble in hydrochloric acid, which solution, after the hydrosulphuric acid has been completely expelled by heat, gives a white precipitate when dropped into water, which, however, is redissolved upon the addition of tartaric acid; this solution yields an orange-red precipitate with hydrosulphuric acid. Antimonious oxy-sulphide is only slightly soluble in ammonium hydrate, but warm liquor potassoe dissolves the greater part of it, leaving behind the antimonious oxide, which may be 136 MANUAL OF CHEMICAL ANALYSIS. washed in water and dissolved in solution of tartaric acid. If these solvents are employed in the reversed order, the oxide may be extracted first, leaving behind the sulphide, now completely soluble in liquor potassae. Examination: About half a drachm of kermes is agitated with about two drachms of water; the filtrate must not affect either blue or red litmus-paper, nor leave a residue when evaporated upon platinum-foil (though, when potassium carbonate has been employed instead of sodium carbonate in the preparation of the kermnes, the solution generally contains traces of potassium salt, and leaves a small fixed residue). Antirrmoniozs Oxide.-The remaining kermes of the preceding test is rinsed, with a little tepid water, through the pierced filter into a test-tube; about 10 grains of tartaric acid are added, and the mixture agitated for a few minutes; it is then filtered, and hydrosulphuric acid added to the filtrate. The ensuing turbidity will be in proportion to the quantity of antimonious oxide contained in the kerines. Arsenic may be detected by dissolving about 10 grains of the kermes in about 3 fluid-drachlns of hot hydrochloric acid; the solution is boiled until the odor of hydrosulphuric acid entirely ceases, and is then filtered; one fluid-drachm of hydrochloric acid and a piece of tin-foil (real), or about 25 drops of a concentrated solution of stannous chloride, are now added, and the mixture heated; it must remain clear, as a brown turbidity would indicate the presence of arsenic. The following confirmatory test may also be employed: HIalf a drachm of the antimonious oxy-sulphide and six fluiddrachms of hydrochloric acid of 1.12 to 1.15 spec. grav. are introduced into a small flask, which is provided, by means of a twice-perforated cork, with a funnel-tube reaching nearly to the bottom of the flask, and with a long delivery-tube, the end of which dips into a little hydrochloric acid in a long test-tube cooled in ice-water (Fig. 44). Heat is applied to the flask until gentle boiling ensues, and this is continued until nearly half of the liquid has distilled-over, the orifice of the delivery-tube being constantly kept below the level of the acid. If arsenic be present, a yellow deposit within the delivery-tube above the ANTIMONIUM. 137 recipient, and a turbidity of the hydrochloric acid and distillate in the receiving-tube, will occur, which latter appears at first white, but gradually, when allowed to stand in the corked test-tube, becomes a yellow, flocculent precipitate. FIG. 44. If the precipitate be considerable, it should be collected upon a filter, washed with a few drops of water, dried, and transferred, with a little potassium cyanide, into a dry reduction-tube; when the humidity is expelled by a gentle heat, stronger heat is applied to produce the arsenic mirror. Admixtures offerric or ferrous oxides are readily detected by an infusible brown residue when the mineral kermes is fused upon charcoal before the blow-pipe; and in the solution of the kermes in hydrochloric acid, if; when diluted and filtered, it yields a deep-blue turbidity upon the addition of potassium ferrocyanide. Admixtures of powdered silicates (brick-stone, etc.) remain unfused before the blow-pipe, and undissolved in hydrochloric acid. 138 MANUAL OF CHEMICAL ANALYSIS. ANTIXONII SULPHURETUX NIGRUXI. ANTIMONIUM SULPHIURATUM NIGRUM. STIBIUM SULPHURATUM CRUDUM. Native Sulphide of Antimony. Tri-sulphide of Antimony. Antimonious Sulphide. Heavy fused masses which, when broken, present a striated crystalline texture, and a lead-gray metallic brilliancy; when pulverized, they form a; dark iron-gray powder. Spec. grav. about 4.6. When heated upon charcoal before the blow-pipe, b)lack antimonious sulphide fuses and burns, emitting thick white fumes and the odor of sulphurous acid; when mixed with some dried sodium carbonate and potassium cyanide, and heated in the same way, metallic globules are obtained, which are brittle when cooled. Black antimonious sulphide, when reduced to a fine powder, is soluble in concentrated boiling hydrochloric, nitric, and sulphuric acids, and in a strong boiling solution of potassium hydrate. The solution in hydrochloric acid, when dropped into water, produces a copious white turbidity, which turns orange-red -upon addition of hydrosulphuric acid (a brown or black color of the precipitate would indicate the presence of lead or other metals). The native antimonious sulphide generally contains sulphides of iron, lead, copper, and arsenic; and there are also found, especially in the commercial black powder, silicates and mineral admixtures. Examination: Arsenic may be detected by dissolving about 15 grains of the black antimonious sulphide in 3 fluid-drachms of boiling concentrated hydrochloric acid; when the hvdrosulphuric acid is expelled by continued boiling, the solution is filtered into a test-tube, and the filtrate, after the addition of 1 fluid-drachm of concentrated hydrochloric acid and about 20 drops of a concentrated solution of stannous chloride, is heated to boiling; a brown turbidity would indicate arsenic. Arsenic and Lead.-Another test for arsenic may be combined with that for lead. Half a drachm of the black antimo ANTIMONIUM. 139 nious sulphide is treated with 6 drachms of hydrochloric acid in exactly the same mode as described on page 136, the operation, as well as the process, being the same. If the sulphide contains any arsenic, a yellow deposit will be formed in the delivery-tube, and the hydrochloric acid of the receiver will show a turbidity, which is at first white, but becomes gradually a yellow flocculent precipitate. If the sulphide contains lead, this will be indicated in the remainder in the flask, by the formation of small white needles after cooling, which will increase in quantity upon the addition of a dilute solution of tartaric acid. They may be collected upon a filter, washed with cold diluted hydrochloric acid, and subsequently dissolved upon the filter in boiling water; the obtained filtrate is, if necessary, refiltered until clear, and is then tested for lead in separate portions, by sulphuric acid, by potassium iodide, and by hydrosulphuric acid. Jfetals may be detected in black antimonious sulphide by dissolving a little of it in boiling nitric acid; the solution is diluted with about four times its bulk of water, is filtered until clear, and is then tested in separate portions with one drop of sulphuric acid for lead, with potassiurn ferrocyanide for iron, and by over-saturation with ammonium hydrate for cop.per; in the latter test the liquid has to be filtered, if necessary, and the filtrate will have a bluish appearance, if copper is present. Admixtures of black manganic peroxide, of pyrites, and of other crude minerals, are recognized by dissolving the black powder in boiling hydrochloric acid; the first-named gives rise to the evolution of chlorine, the latter remain mostly undissolved. The artificially-prepared black antirnonious sulphide contains frequently more or less metallic antimony, which may be recognized by its insolubility in warm hydrochloric acid, remaining behind in minute brilliant iron-gray particles, which, however, dissolve upon the addition of potassium chlorate. 140 MANUAL OF CHEMICAL ANALYSIS. ANTIMONII SULPHURETUM AURANTIACUM. ANTIMONIUM SULPHURATUM. ANTIMONIUM SEU STIBIUM SULPHURATUM AURANTIACUM. SULPHUR AURATUM ANTIMONII. Golden Sulphur. Penta-sulphide of Antimony. Antimonic Sulphide. A fine orange-red powder,* nearly odorless and tasteless, becoming gradually paler colored by the action of air and light; when heated in a dry test-tube, it gives off sulphur, leaving behind black antimonious sulphide; when heated upon charcoal before the blow-pipe, it burns away with a pale, bluish flame, emitting the odor of sulphurous acid, and causing a white incrustation of the coal. Antimonic sulphide is insoluble in water and alcohol, and in diluted mineral acids. When treated with ten to fifteen times its weight of warm concentrated hydrochloric acid, it dissolves for the most part with effervescent evolution of hydrosulphuric acid, leaving behind a scanty residue of red-colored sulphur; the solution, when deprived of the hydrosulphuric acid by heat, produces, when dropped into water, a white turbidity, disappearing upon the addition of tartaric acid, which solution is precipitated orange-red by ammonium sulphydrate. Antimonic sulphide is completely soluble in potassium hydrate; triturated with a little water, and added to solutions of ammonium hydrate or alkaline carbonates and digested for some time, it is nearly or completely dissolved; if a small residue is left, it will dissolve in solution of tartaric acid. Examination: Half a drachm of the antimonic sulphide is triturated with one ounce of tepid water and agitated for about ten minutes; after subsidence, the supernatant water should not act upon neutral litmus-paper, nor leave a residue upon evaporation, nor, when acidulated with a few drops of nitric acid, yield a white turbidity, either with barium or with argentic nitrate. Antimonious oxide may be detected in the sulphide left in the preceding test, by adding a few grains of tartaric acid and agitating the mixture for a few minutes; the subsequent filtrate * The color is the brighter and lighter, the more dilute the solution was from which it is precipitated, and the darker, the more concentrated it was. ANTIMONIUM. 141 is then tested with hydrosulphuric acid; the occurrence of an orange-red turbidity or precipitate would indicate antimonious oxide. Antimonious Sulphide.-A small portion of the golden sulphur, treated with solution of tartaric acid, and left in the flask or test-tube, is washed, and then repeatedly treated with ammoniam hydrate; complete solution must ensue, as a brown remainder would indicate antimonious sulphide. Arsenic may be detected by triturating about 10 grains of the antimonic' sulphide and 10 grains of sodium bicarbonate with half a fluidounce of water; the mixture is macerated in a FIG. 45. corked flask for about half an hour, with occasional agitation, is then filtered, and the filtrate over-saturated with hydrochloric acid; a lemon-yellow precipitate, occurring at once or after a short time, would indicate arsenic. Another test for arsenic is to dissolve 10 grains of the antimonic sulphide in about 3 fluid-drachms of concentrated hydrochloric acid, diluted with 30 drops of water; the solution is heated until the hydrosulphuric acid is completely expelled; it is then filtered, and the filtrate, after the addition of 1 fluiddrachm of hydrochloric acid, and about ten drops of concentrated solution of stannous chloride, is heated to boiling; an ensuing brown turbidity would indicate arsenic. 142 MANUAL OF CHEMICAL ANALYSIS. If a confirmatory test is required, some of the antimonic sulphide may be mixed and agitated for a few minutes with a cold saturated solution of crystallized ammonium carbonate; the subsequent filtrate is evaporated to dryness in a porcelain capsule; the residue is scraped off by means of a pestle and a little powdered magnesite or pumice-stone; after the addition of a little potassium cyanide, the powder is once more warmed, and, when dry, is introduced into a warm reductiontube, and heated to redness to produce the arsenic mirror (Fig. 45). Admixtures of ferric oxides and of silicates are indicated by their insolubility in potassium hydrate, as well as by their stability at a red heat upon charcoal. Iron is recognized in the diluted and filtered hydrochloric-acid solution, by a blue turbidity with potassium ferrocyanide. AQUA AIMMONIE. LIQUOR AMMONILE. AQUA SEU LIQUOR AMMONII CAUSTICI. Solution of Ammonia. Solution of Ammonium Hydrate. Aqua ammonice is an aqueous solution of the gaseous hydrogen nitride called ammonia; this gas is soluble in water to an extraordinary degree, one volume of water at 0~ C. absorbing 1149, and, at 15~ C., 783 volumes of the gas; the quantity of ammonium hydrate contained in the commercial and officinal solutions varies from 32 to 10 per cent. by weight of gas, the latter strength corresponding with a spec. grav. of 0.958 —0.960 at 15~ C., being the average strength of the aqua ammonice of the majority of the pharmacopoeias. The United States and the British pharmacopceias include also an almost-saturated solution, Aqua Ammonise fortior, the former of 0.900 spec. grav., containing 29 per cent., the latter of 0.891 spec. grav., containing 32.5 per cent. of the gas. This gas is also soluble in alcohol, which solution is officinal as Spiritus Ammonie, or Spiritus Armlmonii caustici Dzondii, AQUAE. 143 generally of a strength containing 10 to 12 per cent. of the gas. These solutions have the properties of the gaseous ammonium hydrate, its pungent odor, sharp burning taste, and caustic action upon animal membranes; they have strong alkaline reactions, and form white fumes when brought into contact with the vapors of chlorine or acids, however diluted with atmospheric air they may be. Solution of ammonium hydrate is miscible with water, glycerin, and alcohol, and is saturated by all acids; it decomposes and precipitates most of the earthy and metallic oxides from their compounds; several of these precipitates are redissolved in an excess of the precipitant. It also precipitates most of the alkaloids. The purity of commercial aqua ammonie depends upon the mode of preparation, the materials employed, and the water aised for the absorption of the gas. For medicinal use, distilled water ought to be employed, while this precaution is not required for solutions used in the arts and trades. The strength of solutions of ammonia may be determined by ascertaining their specific gravity; this method, however, is reliable and accurate only when the water contains ammonium hydrate alone, and is free from other, and especially from fixed, substances, which would increase the density of the solution. For Volumetric Estimation, see page 58. Examination: Fixed substances are recognized by remaining behind upon evaporation of a little of the aqua ammonia upon platinum-foil or a watch-glass. Ammonium carbonate is detected by mixing equal volumes of aqua ammonie and lime-water; a turbidity would indicate carbonate. Empyreuma, if not recognized by the odor, will be brought out distinctly by over-saturating in a beaker with diluted nitric acid a mixture of equal parts of aqua ammonioe and water. Calcium hydrate is detected by testing the aqua ammonim with ammonium oxalate. Chloride, Cyanide, and Sul4phate.-About two ounces of aqua ammonia are slightly over-saturated with nitric acid, and the solution evaporated to dryness. The residue is dissolved in 144 MANUAL OF CHEMICAL ANALYSIS. a little water; small portions of this solution are tested severally with argentic nitrate for chloride and cyanide, and with barium nitrate for sulphate; when a precipitate has been formed with argentic nitrate, its nature may be ascertained by slightly over-saturating a little of the aqua ammonia with hydrochloric acid, and then testing it with a few drops of solution of ferric chloride; a greenish-blue coloration or blue precipitate would indicate the presence of cyanide; if such reaction does not occur, the silver precipitate, if insoluble in diluted nitric acid, consists of argentic chloride. iMetals are detected in aqua ammo/nie, neutralized with nitric acid, by hydrosulphuric acid, and by subsequent addition of the same aqua ammonive. A dark reaction in either instance would indicate metals. The ammonia-strength of impure aqua ammonite, or of crude ammoniacal liquors (free of other alkaline hydrates or carbonates), may be estimated by the following simple method: One hundred cubic centimetres of oxalic acid test-solution (page 56) are poured into / of| a beaker, and reddened with a few drops of litmus-solution. Then the ammoniacal liquor is added from a burette (Fig. 46), until the red color commences to pass into a violet one. The number of cubic l centimetres required for neutralization is then read off, and is used as divisor of'1'i the number 170; the quotient indicates at once the percentage of ammonia contained in the ammoniacal liquor. For instance, if 40 cubic centimetres of the latter have been used, it contains 4.25 per cent.; if 29 cubic centimetres, it contains 5.86 per cent.; if 17 cubic centimetres, it FIa. 46. contains 10 per cent. of ammonia. AQUAS. 145 T A 1B Is E OF THE QUANTITY BY WEIGHT OF AMMONIA CONTAINED IN 100 PARTS BY WEIGHT OF AQUA AMMONIE AT DIFFERENT DENSITIES. TEMPERATURE 14~ C. 0e o Ci i C;P Specific ~ 0 Specific 2 Specific ~. Specific o. f1ravity. t Gravity. C i Gravity. 2 Gravity. l 5 0.8907 33.0 0.9116 24.6 0.9373 16.2 0.9677 7.8 0.8911 32.8 0.9122 24.4 0.9380 16.0 0.9685 7.6 0.8916 32.6 0.9127 24.2 0.9386 15.8 0.9693 7.4 0.8920 32.4 0.9133 24.0 0.9393 15.6 0.9701 7.2 O.8925 32.2 0.9139 23.8 0.9400 15.4 0.9709 7.0 0.8929 32.0 0.9145 23.6 0.9407 15.2 0.9717 6.8 0.8934 31.8 0.9150 23.4 0.9414 15.0 0.9725 6.6 0.8938 31.6 0.9156 23.2 0.9420 14.8 0.9733 6.4 0.8943 31.4 0.9162 23.0 0.9427 14.6 0.9741.6.2 0.8948 31.2 0.9168 22.8 0.9434 14.4 0.9749 6.0 0-8953 31.0 0.9174 22.6 0.9441 14.2 0.9757 5.8 0.8957 30.8 0.9180 22.4 0.9449 14.0 0.9765 5.6 0.8962 30.6 0.9185 22.2 0.9456 13.8 0.9773 5.4 0.8967 30.4 0.9191 22.0 0.9463 13.6 0.9781 5.2 0.8971 30.2 0.9197 21.8 0.9470 13.4 0.9790 5.0 0.8976 30.0 0.9203 21.6 0.9477 13.2 0.9799 4.8 0.8981 29.8 0.9209 21.4 0.9484 13.0 0.9807 4.6 0.8986 29.6 0.9215 21.2 0.9491 12.8 0.9815 4.4 0.8991 29.4 0.9221 21.0 0.9498 12.6 0.9823 4.2 0.8996 29.2 0.9227 20.8 0.9505 12.4 0.9831 4.0 0.9001 29.0 0.9233 20.6 0.9512 12.2 0.9839 3.8 0.9006 28.8 0.9239 20.4' 0.9520 12.0 0.9847 3.6 0.9011 28.6 0.9245 20.2 0.9527 11.8 0.9855 3.4 0.9016 28.4 0.9251 20.0 0.9534 11.6 0.9863 3.2 0.9021 28.2 0.9257 19.8 0.9542 11.4 0.9873 3.0 0.9026 28.0 0.9264 19.6 0.9549 11.2 0.9882 2.8 0.9031 27.8 0.9271 19.4 0.9556 11.0 0.9890 2.6 0.9036 27.6 0.9277 19.2 0.9563 10.8 0.9899 2.4 0.9041 27.4 0.9283 19.0 0.9571 10.6 0.9907 2.2 0.9047 27.2 0.9289 18.8 0.9578 10.4 0.9915 2.0 0.9052 27.0 0.9296 18.6 0.9586 10.2 0.9924 1.8 0.9057 26.8 0.9302 18.4 0.9593 10.0 0.9932 1.6 0.9063 26.6 0.9308 18.2 0.9601 9.8 0.9941 1.4 0.9068 26.4 0.9314 18.0 0.9608 9.6 0.9950 1.2 0.9073 26.2 0.9321 17.8 0.9616 9.4 0,9959 1.0 0.9078 26.0 0.9327 17.6 0.9623 9.2 0.9967 0.8 0.9083 25.8 0.9333 17.4 0.9631 9.0 0.9975 0.6 0.9089 25.6 0.9340 17.2 0.9639 8.8 0.9983 0.4 0.9094 25.4 0.9347 17.0 0.9647 8.6 0.9991 0.2 0.9100 25.2 0.9353 16.8 0.9654 8.4 0.9106 25.0 0.9360 16.6 0.9662 8.2 0.9111 24.8 0.9366 16.4 0.9670 8.0 10 146 MANUAL OF CHEMICAL ANALYSIS. With the decrease and increase of temperature, the density of aqua ammoniie suffers a corresponding increase or decrease, amounting for each degree of the centigrade thermometer in either directionFor aqua ammoniav of a specific gravity of 0.9001 to that of 0.9221 to about 0.00055. 44 " " " " 0.9251 " 0.9414 " 0.0004. 4" " " " 0.9520 " 0.9670 " 0.0003. " " " " 0.9709't 0.9831 " 0.0002. For instance: An aqua ammonii of 0.9593 spec. grav., at 14~ C., containing 10 per cent. of ammonia, will have, at 180 C., a spec. grav. of (0.9593-0.0003 x4=) 0.9581, and, at 12~ 0., a spec. grav. of (0.9593+,0.0003 + 2=) 0.9599. AQUA AXIYGDALARUM AILARARUMo Bitter-Almond Water. Bitter-almond water, when prepared from the essential oil of bitter almonds, is a clear, when derived by distillation from bitter almonds, mostly a turbid, colorless liquid, with the odor of oil of bitter almonds, which odor must not disappear after the elimination of the hydrocyanic acid by argentic nitrate. It should be of such strength, that 1,000 parts contain one part of anhydrous hydrocyanic acid, which is associated in the water with benzoic aldehyde. Ferrous salts render no reaction with bitter-almond water; but a slight blue precipitate will take place when, after the addition of the reagent, first a few drops of liquor potassae are added, and subsequently a slight excess of diluted hydrochloric acid. Argentic nitrate and mercurous nitrate produce but a slight turbidity in bitter-almond water; but, when a few drops of aqua ammoniea have been added previously, and the liquid is then over-saturated with diluted nitric acid, argentic nitrate will yield a white, and mercurous nitrate, upon warming, a dark-gray precipitate. The quantity of hydrocyanic acid in bitter-almond water may be determined by weighing 1,000 grains of the water into a vial, and adding and agitating it with a solution of 8 grains of argentic nitrate in 60 grains of water and 30 grains of aqu AQUAE. 147 ammonim; 2 drachms of diluted nitric acid are then added, and the whole is gently warmed by immersing the flask in hot water. The precipitate of argentic cyanide is collected upon a tared and moist filter, washed, and dried, and should weigh not less than 5 grains, indicating one part by weight of anhydrous hydrocyanic acid in 1,000 parts of the water. AQUA CHLORI. AQUA CHLORINII. LIQUOR CHLORI. chlorine - Trater. A saturated solution of chlorine gas in distilled water, containing about twice its bulk, and 0.4 per cent. by weight, of the gas. Chlorine-water has the pale, greenish-yellow color, the irritating and suffocating odor, and the chemical properties, of the gas. When cooled to near the freezing-point, it forms yellow crystalline plates of chlorine hydrate, which dissolve again upon increase of the temperature. When heated, it loses the chlorine by evaporation; when exposed to sunlight, it is gradually changed, with the participation of the elements of water, into hydrochloric acid and free oxygen. Chlorine-water destroys instantaneously the color of dilute indigo-solution, and all vegetable colors. By the strong affinity of chlorine for all the elements except oxygen, nitrogen, and carbon, and for many compound radicals, it is a powerful chemical agent, and, especially by its property of abstracting or displacing hydrogen, bromine, and iodine, from almost all their combinations by equivalent substitution, a most energetic oxidizer. Examination: Itydrochloric acid, and consequently decomposition, is indicated when blue litmus-paper, upon being immersed in chlorinewater, is reddened before it is bleached; such decomposition may further be ascertained by filling a one-oulice vial, in which a few globules of mercury have been placed, with the chllorinewater, and agitating the corked bottle until the odor of clllo 148 MANUAL OF CHEMICAL ANALYSIS. rine has entirely disappeared. The water should now leave blue litmus-paper unchanged, and should form no precipitate with argentic nitrate, although all chlorine-water, however freshly prepared, will yield a slight turbidity with the latter reagent. Loss of the strong odor of the gas, an acid reaction upon litmus, and the formation of a white precipitate with argentic nitrate, would indicate a degree of decomposition which renders the chlorine-water unfit for use. Miinzeral salts, as an evidence of the employment of springwater for the absorption of the gas instead of distilled water, may be ascertained by the fixed residue remaining upon evaporation of a little of the water on platinum-foil, or on a watchglass; as well as by testing it, after addition of a little aqua ammonite, with oxalic acid; a white precipitate would prove the presence of calcium salts, and would be indicative of springwater. Estimation of the strength of chlorine-water. I. Approximate estimation: 1. One hundred parts by weight of chlorine-water are agitated with a solution of 3 parts of crystallized or granulated ferrous sulphate (free from peroxide) in 10 parts of water acidulated with hydrochloric acid. When, now, a few drops of diluted test-solution of potassium permangainate are added, no discharge of its color should take place. 2. One fluidounce of chlorine-water is mixed with a solution of 10 grains of ferrous sulphate (fiee from peroxide) in 2 drachms of water. This mixture must yield no blue precipitate upon the addition of potassium ferricyanide. II. Quantitative volumetric estimation: One ounce by weight of chlorine-water is mixed with a solution of 10 grains of potassium iodide in 2 drachms of water; to this is added from a burette (Fig. 47), a test-solution of sodium hyposulphite, containing 10 weight-parts of the reagent in 100 volume-parts of the solution, until the brown color has just disappeared. The number of volume-units required, divided by seventy, gives as quotient the quantity by weight of the chlorine contained in one ounce of the solution. For volumetric estimation, with the standard test-solution of sodium hyposulphite, see page 64. AQUAE. 149 AQUA DESTILLATA. Distilled Water. Distilled water must not leave a fixed residue upon evaporation. When reduced by evaporation to one-fourth or one-sixth of its volume, and then tested in separate portions with lime-water for carbonates, with argentic nitrate and a few drops of nitric acid for chlorides, with barium nitrate for snlpphates, with ammonium oxalate for calciuzm, and with hydrosulphuric acid and by subsequent acidulation with hydrochloric acid for metals, it must in no instance yield any reaction. Ammonium salts may be detected by a white turbidity, occurring after fifteen to thirty minutes, when one drop of a strong solution of potassium carbonate, and subsequently = 3 or 4 drops of solution of mercuric chloride, are added to about one ounce of the -- - - water. FIG. 47. Nitrous acid may be detected by mixing in a beaker a little sulphuric-acid mucilage of starch and one drop of a solution of potassium iodide; the mixture must remain colorless; the water under examination is then added, stirring it with a glass rod; if the liquid assumes a bluish tint, traces of nitrous acid are indicated. NNitric acid may be detected by reducing about 2 ounces of the water by evaporation to about 2 drachms; to these are added, in a test-tube, a few drops of solution of aniline sulphate, 150 MANUAL OF CHEMICAL ANALYSIS. and, afterward, about 10 drops concentrated sulphuric acid; the liquid is slowly stirred with a glass rod; if nitric acid be present, rose-colored lines will appear after a while, and the whole liquid also will gradually assume this tint. Organic substances may be recognized in the water, if it is free from nitrous acid, by warming to near 600 C. about six ounces of it in a beaker placed upon white paper; then a few drops of sulphuric acid, and subsequently a very dilute solution of potassium permanganate (1:1000), are added drop by drop. If the water is entirely free from organic substances, it should assume and retain, upon the addition of the first drop of the solution, a slight rose-colored hue, which increases in intensity progressively with the number of drops added. If the water, however, contains organic substances, the coloration received from the first drop will either not appear at all, or will soon disappear. If decoloration takes place, an approximate estimate of the quantity of organic substances contained in the water may be had from the number of drops which it is necessary to use before this effect ceases, and the permanent color begins to appear. This same decoloration is also produced when the water contains certain inorganic substances, as nitrous, sulphurous, or hydrosulphuric acid, ferrous and other sub-salts, and other readily-oxidized substances. ARG]ENTI NITRAS. ARGENTUM NITRICUM. Nitrate of Silver. Argentic Nitrate. Anhydrous, colorless, transparent, rhombic plates, or, when fused and cast into moulds, thin, white, transparent, cylindrical sticks (lunar caustic). Permanent in the air, but decomposed by the combined action of organic substances and solar light. Argentic nitrate fuses at 219-220~ C.; at about 3200 C. it is decomposed; when fused upon charcoal before the blow ARGENTUM. 151 pipe, it deflagrates, emitting yellow vapors and sparks, while a reticular coating of metallic silver remains behind. Argentic nitrate is soluble in an equal weight of cold, and in half that quantity of boiling, water; it is also soluble in alcohol, but only sparingly in ether and chloroform; its strong aqueous solution, therefore, when dropped into alcohol, suffers no precipitation; it is, however, precipitated by a solution of ferrous sulphate acidulated with nitric acid. When the supernatant liquid is decanted from the precipitate and placed upon strong sulphuric acid (Fig. 48), it yields the dark-brown reacFIG. 48. tion of the nitrogen oxides on the line of contact between the two fluids. The aqueous solution of argentic nitrate must be clear; a white turbidity would indicate argentic chloride or nitrite; a bluish color, cupric nitrate; a grayish-black turbidity in the solution of the fused salt, a partial reduction by'an excess of heat in the fusion, or cupric chloride or oxide. The solution gives a white, curdy precipitate with hlydrochloric acid and with soluble chlorides, a black one with hydrosulphuric acid, a brown one with the alkaline hydrates, a white one with the carbonates and oxalates, and a yellow one with tri-basic phlosphoric acid and its soluble salts. 152 MANUAL OF CHEMICAL ANALYSIS. Argentic nitrate consists, in 100 parts, of 68.23 parts of argentic oxide (containing 63.53 parts of silver), and 31.77 parts of nitric acid; it yields, when completely precipitated by hydrochloric acid or chlorides, 84.39 parts of dry argentic chloride. Examination: Potassiuum nitrate is used to adulterate both the fused and the crystallized argentic nitrate; sodium nitrate cannot well be employed for such adulteration, on account of its hygroscopic character; argentic nitrate fuses with either of these alkaline nitrates in all proportions, and such a mixture in the proportion of one part of argentic nitrate and 2 parts of potassium nitrate is officinal in some pharmacopoeias. Such admixture is indicated in the fused silver salt, by an alteration of its appearance, which is less translucent, whiter, and without the distinct radiate crystalline structure of pure argentic nitrate. Among the methods of detecting such an adulteration, the following are the readiest and most practicable ones: 1. A concentrated aqueous solution of argentic nitrate is dropped into ten times its bulk of strong alcohol; if' potassium nitrate be present, it will separate after a while in small, white granules, as it is far less soluble in alcohol. Sodium nitrate cannot be detected by this test, since it is more soluble in alcohol. 2. A small quantity of a dilute solution of argentic nitrate is completely precipitated with diluted hydrochloric acid; the liquid is then warmed, and must, when filtered, leave no fixed residue upon evaporation; such a residue would indicate alkaline nitrates or other impurities. 3. A number of larger and smaller crystals are mixed and broken in a mortar; a small portion of the coarse powder, or fused argentic nitrate, if this is to be tested, is fused and completely reduced on charcoal before the blow-pipe (Fig. 49); a slight reticular metallic coating will remain behind, and some alkaline carbonate, if potassium or sodium nitrates were present; they will be recognized by the alkaline reaction, when moist, red litmus-paper is pressed upon the spot of the coal where the fiusion took place. Argentie chloride is indicated, as stated, by a white turbid ARGENTUM. 153 ity of the solution of argentic nitrate; its identity may be ascertained by its dissolving upon the addition of ammonium hydrate, but remaining insoluble in nitric acid. Copper and iron may be detected by completely precipitating the aqueous solution of the salt with hydrochloric acid, and by subsequent approximate neutralization of the filtrate with aqua ammonioe; this solution is then tested with a few drops of a solution of potassium ferrocyanide; a red precipitate would indicate copper, a blue one, iron; copper may also be detected, or its presence confirmed, by dissolving about 5 grains of the argentic nitrate in 10 drops of water, and by FIG. 49. dropping this solution into a small test-tube containing about half a drachm of aqua ammoniue; an ensuing blue coloration would indicate copper; a white turbidity, lead or zinc. Nitrous acid, traces of which are frequently met with in the fused argentic nitrate, causing slight turbidity upon solution, may be detected by completely precipitating the solution with potassium chloride. The filtrate is then tested with a few drops of sulphuric-acid mucilage of starch, to which previously has been added one drop of solution of potassium iodide; if nitrous acid, free or combined, be present, a blue coloration takes place. 154 MANUAL OF CHEMICAL ANALYSIS. ARGENTI OXIDUX. ARGENTUM OXYDATUM. Oxide of Silver. Argentic Oxide. An olive-brown, odorless powder, becoming black when heated, and decomposed at a red heat, leaving behind spongy metallic silver; it is also gradually reduced by the solar light. Argentic oxide is sparingly soluble in water, but freely dissolved in ammonium hydrate as well as in boiling nitric acid; it is insoluble in the fixed alkaline hydrates. Its aqueous solution has an alkaline reaction and a metallic taste, and is rendered turbid by a small quantity of carbonic acid, but becomes clear again by an excess of it. The purity of argentic oxide is ascertained by its solubility in aqua ammonias, and also in hot nitric acid, without effervescence, and by the fact that this solution, when completely precipitated with hydrochloric acid, gives a filtrate which leaves no residue upon evaporation, and yields no reaction with hydrosulphuric acid and subsequent over-saturation with aqua ammonie. ARSENICI IODIDUI. ARSENICUM IODATUM. Iodide of Arsenic. Arsenious Iodide. An orange-red or purple, crystalline solid, fused and volatilized by heat; it is soluble in 31 parts of water, and also in glycerin, alcohol, ether, and carbon bisulphide; its aqueous solution is yellow, and gradually and partly decomposes into arsenious and hydriodic acids; it forms a yellow precipitate with hydrosulphuric acid, and emits violet vapors of iodine when heated with nitric acid. ATROPIA. 155 ATROPIA. ATROPINUM. Atropia. Atropine. Colorless, silky, acicular crystals, or a yellowish-white crystalline powder, without odor, and of a bitter and acrid taste. Heated upon platinum-foil, atropia fuses at about 90~ C.; at 140~ C. it is partly volatilized and decomposed, swelling and emitting white fumes which burn with a white flame, leaving some coal, which is wholly dissipated at a red heat. Atropia is soluble in about 300 parts of cold, and in a less amount of boiling; water, in 2~ parts of cold alcohol, in about 35 parts of ether, and freely in amylic alcohol and in chloroform. The aqueous solution has an alkaline reaction, and powqrfully dilates the pupil of the eye. Atropia dissolves in concentrated nitric acid, imparting to it a yellowish color, and in concentrated sulphuric acid, without color (sometimes a transient purple tint appears), but the latter solution becomes yellow. after some time; it remains, however, unchanged upon addition of nitric acid, but gradually assumes a green color' upon addition of potassium bichromate. When some peroxide of manganese is added to the solution of atropia in strong sulphuric acid, the odor of oil of bitter almonds is evolved, and afterward that of benzoic acid. The aqueous solution of atropia must remain clear upon addition of a few drops of solution of sodium carbonate; a white turbidity would indicate a contamination with belladonnia. This is also indicated in atropia by its lesser solubility in water and a greater solubility in ether. ATROPIME SULPHAS. ATROPINUM SULPHURICUM. Sulphate of Atropia or Atropine. Atropia Sulphate. A colorless, slightly-crystalline powder, which fuses when heated upon platinum-foil, assumes a transient red coloration, 156 MANUAL OF CHEMICAL ANALYSIS. and is finally wholly dissipated by heat. It gives the same reactions as atropia with concentrated niti'ic and sulphuric acids, and, in the latter solution, with peroxide of manganese. Atropia sulphate is freely soluble in water and alcohol, but insoluble in ether and chloroform. Its aqueous solution is neutral, gives a white precipitate with solutions of barium salts, and also dilates the pupil of the eye. A solution of one grain of atropia sulphate in half an ounce of water must remain unchanged when a portion of it is tested with solution of sodium carbonate; a white turbidity would indkcate a contamination with belladonnia; another portion of it may be heated with a few drops of Fehling's solution; the occurrence of a reddish-brown deposit would indicate the presence of glucoside. BARII CHLORIDUM. BARYUM CHLORATUM. BARYTA MURIATICA. Chloride of Barium. Barium Chloride. Colorless and transparent, flat, four-sided plates, containing two molecules (six per cent.) of water of crystallization; they are permanent in the air, but lose their water at 100~ C., leaving the anhydrous salt as a white mass, which, when heated, fuses without decomposition, and imparts a yeilowish-green color to the flame. Barium chloride is soluble in about 21 parts of cold, and 1part of boiling, water, and but sparingly in alcohol; it is less soluble in diluted hydrochloric and nitric acids, and is therefore partly precipitated from its aqueous solution, if not very dilute, upon the addition of concentrated hydrochloric or nitric acids; the salt is, however, redissolved ujpon dilution with water. The aqueous solution has a bitter, nauseous, saline taste, does not act upon litmus-paper, and yields copious white precipitates with sulphuric acid and sulphates, and with argentic nitrate, insoluble in diluted nitric acid, but the last one soluble in ammonium hydrate; it forms precipitates also with phosphoric acids and the phosphates, and with the BISMUTHUM. 1s7 alkaline carbonates; they are soluble in hydrochloric and nitric acids. Examination: Alumrina may be detected, in the dilute aqueous solution, by a white turbidity with aqua ammoniae; a bluish coloration of the liquid would indicate copper. Metals will be detected by a dark precipitate, or, if only traces of iron are present, by a dark-greenish coloration, upon addition of ammonium sulphydrate to the aqueous solution; if a precipitate be formed, it is collected upon a filter, and dissolved in a few drops of nitric acid, and the solution over-saturated with aqua anmonioe; a blue coloration would confirm the presence of copper; a brown precipitate, that of iron. Calciutm, jpotassium, and sodium chlorides, are detected, in the aqueous solution, by completely precipitating the same with diluted sulphuric acid, and by subsequent examination of the filtrate in separate portions; calciumv is recognized by a white precipitate when one of these portions is slightly oversaturated with aqua ammonite, and tested with ammonium oxalate. Potassium and sodium cahloricdes will be indicated by a fixed residue upon complete evaporation of another part of the filtrate; they may be distinguished by dissolving the residue in a few drops of water, and testing the solution with potassium antimoniate; a white turbidity would indicate sodium salt. Strontiumr chloride is detected by agitating some of the powdered salt with an equal weight of strong alcohol, and by igniting the filtrate; the presence of strontium will be indicated by a red color of the flame, especially apparent toward the end of the combustion. BISMUTHI ET AMMONII CITRAS% BISMUTHUM ET AMMONIUM CITRICUM. Citrate of Bismuth and Ammonium. Bismuth and Ammonium Citrate. White, glossy, translucent scales, of a slightly acidulous and somewhat metallic taste. When heated upon charcoal, before the blow-pipe, they yield a black fuse, with a yellow coating 158 MANUAL OF CHEMICAL ANALYSIS. of the coal; when heated in a dry test-tube, they are charred, with the evolution of moisture and of ammoniacal and empyreunatic vapors; and, at a red heat, a black fuse remains, which, upon cooling, acquires a lemlon- yellow color on the surfaces, and which is readily soludle in warm concentrated nitric acid; this solution, when dropped into a quantity of water, produces a white turbidity. Heated with liquor potasse, it emits the odor of ammonia. Citrate of bismuth and ammonium is readily soluble in water, sparingly so in alcohol, and insoluble in ether and chloroform. By exposure to the air, it loses its transparency, and becomes gradually more or less insoluble; it becomes, however, soluble again upon addition of a little ammonium hydrate. Its aqueous solution reddens blue litmus-paper slightly, gives white precipitates with dilute hydrochloric acid (soluble ill an excess of the acid), with potassium hydrate, and with the alkaline carbonates, the latter precipitate being insoluble in an excess of the precipitants; it is not acted upon by ammonium hydrate; with potassium bichromate, it forms a.yellow precipitate, soluble in dilute nitric acid, and, with hiydrosulphuric acid, a brownish-black precipitate, insoluble in dilute acids or alkaline hydrates. BISMUTHI SUBCARBONAS. BISMUTHUM CARBONICUM. Carbonate, Subcarbonate, or Oxy-Carbonate of Bismuth. Bismuthous Carbonate. A white or yellowish-white, odorless, and tasteless powder, which is blackened when in contact with gaseous or aqueous hydrosulphuric acid. When exposed to heat,-it gives off moisture and carbonic acid (amounting to 9 per cent.), while yellow bismuthous oxide remains behind; when heated with exsiccated sodium carbonate, on charcoal before the blow-pipe, it yields metallic globules of bismuth and an incrustation on the coal, which is orange when hot and yellow when cold. Bismuthous carbonate is insoluble in water, but slightly sol BISMUTHUM. 159 uble in water saturated with carbonic acid; it is readily soluble, with effervescence, in acids, forming solutions which, when nearly neutralized by the bismuthous oxide, produce white precipitates of basic salts when poured into a quantity of water. Examination: Nitrate may be detected, in a solution of the carbonate in acetic acid, by imparting to it a faint bluish tinge; upon adding one or two drops of neutral indigo-solution, and warming, the blue color will disappear, if any nitrate be present. Ammoniuzm salts may be detected by the odor of ammonia, and by white fumes from a glass rod moistened with acetic acid, and held in the orifice of the test-.tube, when the bismuthous carbonate is heated with liquor potasse. The examination for other admixtures or impurities is the same as described with bismuthous nitrate, on pages 160-163. B3ISMUTHI SUBNITRAS. BISMUTHUM SUBNITRICUM. BISMUTHUM ALBUM. Subnitrate.r Oxy-Nitrate of Bismuth. Basic Bismuthous Nitrate. A heavy, white powder, in minute crystalline scales; it reddens moistened blue litmus-paper, and becomes black in contact with hydrosulphuric acid. When heated in a dry testtube, it first emits moisture, and afterward reddish-yellow, acid vapors, leaving a residue which is readily soluble in warm nitric or hydrochloric acid, forming a solution which, when poured into a quantity of water, produces a white precipitate; when heated to redness, a straw-yellow powder of bismuthous oxide (amounting to eighty per cent.-of the bisnmuthous nitrate) remains, which is fusible at a high temperature; when heated will exsiccated sodium carbonate, on charcoal before the blow-pipe, brittle globules of bismuth are obtained, and the charcoal becomes covered with a slight incrustation, which is orange when hot and yellow when cold. Bismuthous nitrate is nearly insoluble in water; upon a 160 MANUAL OF CHEMICAL ANALYSIS. continued digestion, however, it suffers an alteration in its composition, whereby its solubility in water is increased; it is readily soluble in nitric and hydrochloric acids, and these solutions, when poured into a large amount of water, form white precipitates of basic bismuthous salts. Bismuthous nitrate is but sparingly soluble in potassium and sodium hydrates, and but little more so in ammonium hydrate. Examination: Ccarbonates and insoluble admixtizres are detected, the former by effervescence in the cold, the latter by remaining behind, when about 10 grains of the bismuthous nitrate are mixed and dissolved, with the aid of heat, in about three flnid-drachms of a mixture-consisting of equal parts of concentrated nitric acid and water. Chloridcles and sulphates may be detected, in the solution obtained in the preceding test, diluted with an equal bulk of water, and filtered if necessary, by tes~ting it in two separate portions, with a few drops of solution of argentic nitrate for chlorides, and with a few drops of barium nitrate for sulphates. The test for chlorides and sulphates may also be made by adding about 10 grains of the bismuthous flitrate to about three drachms of a boiling, diluted solution of sodium carbonate; after a few minutes' boiling, the mixed fluid, when nearly cool, is filtered, and tho filtrate over-saturated with nitfic acid, and then tested, in separate portions, with argentic nitrate for chlorides and with barium nitrate for sulphates. Salts of Calcium, cliagnesium, ancl Zinc.-About three fluid-drachms of a mixture of equal parts of concentrated hydrochloric acid and water are heated, and so much of the bismuthous nitrate as will be dissolved is added, little by little; about 20 drops of concentrated hydrochloric acid, and subsequently six drachms of water, are then added, and,'fter a while, the solution is filtered; the filtrate is now repeatedly saturated, and completely precipitated, with hydrosulphuricacid gas, and again filtered; the filtrati is then warmed, and slightly over-saturated with sodium carbonate; an ensuing white precipitate would indicate salts of calcium, magnesium, or zinc; if it be comparatively considerable, and sufficient in amount to ascertain its nature, it is collected and washed upon BISMUTtUIM. 161 a filter, and afterward agitated with aqua ammoniae; if a residue remains, it is likewise collected and washed upon a filter, and the filtrate tested with hydrosulphuric acid; a white precipitate indicates zinc salts; the residue upon the filter is dissolved in a few drops of diluted hydrochloric acid, and the solution neutralized by a few drops of aqua ammonite, and then divided into two portions, one of which is tested with ammonium oxalate, for calcium salts, the other with sodium phosphate, for magnesium salts. Calcium phosphates may be detected, in the bismuthous nitrate, by adding to a solution of one part of it, in a sufficient quantity of a mixture of equal parts of nitric acid and water, two parts of citric acid dissolved in a little water, and then adding an excess of aqua ammonioe; the occurrence of a white, bulky precipitate, either at once or after a while, will indicate calcium phosphates. The presence or absence of earthy admixtures in bismuthous nitrate may also be ascertained, by boiling about 10 grains of it, for 10 minutes, in about two fluid-drachms of acetic acid; the liquid is then filtered, and completely precipitated with hydrosulphuric acid; the filtrate must leave no fixed residue upon evaporation; if any such residue remains, earthy oxides are present. 3Metallic Impurities: Lead.-Two dracllms of a mixture consisting of equal volumes of concentrated nitric acid and water are heated, and so much of the bismuthous nitrate is added, in small portions, as will be dissolved; the solution is then decanted, and diluted with four times its volume of water; after about a quarter of an hour, the liquid is filtered, if necessary, and a portion of it tested with one or two drops of concentrated sulphuric acid; if a white precipitate, indicating the presence of lead, occurs, the larger part of the liquid, or the whole of it, is precipitated with sulphuric acid; the precipitate is washed with water by careful decantation, and then agitated for 10 minutes with tepid liquor potassse; the liquid is then passed through a moist filter, and the filtrate mixed with an equal volume of hydrosulphuric acid; a black precipitate will confirm the presence of lead. Copper salts are detected, in the diluted nitric-acid solution 11 162 MANUAL OF CHEMICAL ANALYSIS. of the bismuthous nitrate, by a reddish-brown precipitate with potassium ferrocyanide. Arsenic may surely enough be recognized by its characteristic odor, when a mixture of five grains of the bismuthous nitrate with 10 grains of powdered potassium bitartrate is incinerated, either in an iron spoon or in a small cavity upon charcoal, before the blow-pipe (Fig. 50). FIG. 50. As an additional or confirmatory evidence of the absence or presence of arsenic, either of the two following tests may be applied: About 20 grains of the bismuthous nitrate are added to about two fluid-drachms of concentrated sulphuric acid, in a test-tube or in a small flask, and the mixture boiled; the tube or flask is held, as much as practicable, in an inclined position, so as to allow the nitric and nitrous acid vapors to escape; when the evolution of such vapors ceases, two fluid-drachms of concentrated hydrochloric acid are added, and the mixture is allowed to cool, and may serve, in two separate portions, for the two following tests: 1. One portion of the mixture is added to about an equal volume of concentrated hydrochloric acid, and a piece of tinfoil (real tin), or about 20 drops of concentrated solution of stannous chloride, are added, and heat applied; a brown turbidity of the mixture, either at once or after a while, and a grayish-brown precipitate after subsiding, would indicate arsenic. 2. The other portion of the sulphuric-acid mixture is carefully added to five times its volume of a mixture of equal parts of hydrochloric acid and water, and the mixture carefully BISMUTHUM. 163 poured upon granulated zinc, in a long test-tube, only onetenth of which should be filled by the liquid, taking care that the upper interior walls of the tube do not get wet; a bunch of cotton, moistened with solution of plumbic acetate, is then introduced into the orifice of the tube, and this loosely closed, either by paper moistened with one drop of solution of argentic nitrate, or by a cork provided with two strips of paper, saturated with solutions of plumbic acetate and of argentic nitrate respectively (Fig. 51). The test is then conducted as described on page 30. 164 MANUAL OF CHEMICAL ANALYSIS. A dark coloration of the argentic-nitrate solution would in.dicate arsenic. BISMUTHII VALERIANAS. BISMUTHUM VALERIANICUM. Basic Valerianate of Bismuth. Bismuthous Valerianate. A white, crystalline powder, with the strong odor of valerianic acid. When gradually heated in a porcelain crucible, it emits the odor of valerianic and butyric acids, and becomes black; upon continued heating, bismruthous oxide is left behind, appearing brownish-yellow while hot and straw-yellow on cooling; when heated with exsiccated sodium carbonate, it affords the same reaction as the bismuthous carbonate and nitrate (pages 158, 159). Bismuthous valerianate is insoluble in water, but soluble in hydrochloric and nitric acids, separating an oily layer of valerianic acid, and forming solutions which produce white precipitates with a quantity of water. Twenty grains of bismuthous valerianate, placed in a small tared porcelain crucible, and moistened with a few drops of concentrated nitric acid, yield, when completely incinerated at a red heat, 16 grains of straw-yellow bismuthous oxide. Examination: The solution of bismuthous valerianate in acids, for tests, must be allowed to stand in a cool place for one or several hours, so that the valerianic acid may separate and collect upon the surface, and remain behind upon the paper when the solution is passed through a moist double filter..Bismuthous nitrate or carbonates may be detected by dissolving a few grains of the valerian ate in concentrated hydrochloric acid; effervescence indicates carbonates, and, in this case, a solution of 10 grains of the salt, in a sufficient quantity of concentrated hydrochloric acid, is completely precipitated with hydrosulplhuric acid, and the filtrate slightly over-saturated with sodium carbonate; a white precipitate would indi BROMUM. 165 cate salts of calcium, magnesium, or zinc; they may be discriminated by the same method as-described on page 160. Another part of the solution of the valerianate in hydrochloric acid is diluted with about four times its volume of water, and is faintly tinted with one drop of solution of indigo, and is gently warmed; if decoloration takes place, nitrate is indicated. The examination of bismuthous valerianate, i. e., of its solutions in nitric or hydrochloric acid, for chlorides and sulpAhates, for calcium phophciate and salts of cacium, magnesium, and zinc, and for metallic impurities, is performed in the same way as with the corresponding solutions of bismuthous nitrate, described on pages 160-163. BRO1UM. BROMINI U M. Bromine. A heavy, dark-red, very volatile liquid, of an intense and suffocating odor, somewhat resembling that of chlorine; its spec. grav. is 2.95 to 3.00. Bromine solidifies at -7~ C., forming, at temperatures below that, a dark lead-gray, brittle, crystalline mass, of a semi-metallic lustre; from -6~ to 63~ C., it is liquid, and volatile at common temperature; at 63~ it boils, forming yellowish-red vapors. Bromine is soluble in 32 parts of water, yielding an orangeyellow solution, which has the odor of bromine, bleaches vegetable colors and solution of indigo, and colors starch orangeyellow, and which, when cooled down to 0~ C., forms small yellow scales of solid hydrate; the aqueous. solution of bromine is deprived of its bromine and of its color when agitated with ether, chloroform, or carbon bisulphide; these ethereal solutions, however, are themselves decolorized when agitated with potassium hydrate; but either of them, with the exception of carbon bisulphide, will form a new solution of the bromine, and consequently regain the color, upon the addition of an excess of any mineral acid. 166 MANUAL OF CHEMICAL ANALYSIS. Bromine is freely soluble in alcohol, chloroform, benzol, carbon bisulphide, and the alkaline hydrates, and is miscible with ether in all proportions. In its chemical relations, it resembles chlorine, having a powerful affinity for hydrogen, though not quite so strong, and hence it acts with energy on many organic compounds, abstracting hydrogen with equivalent substitution. Examination: Chlorine may be detected by shaking a little of the bromine with three times its volume of water; the liquid is then poured into a conical glass, and the supernatant aqueous solution decanted into a test-tube, and shaken with an equal volume of ether; the lower or aqueous layer is then transferred, by means of a pipette, to another test-tube, and boiled until the ether, dissolved, is volatilized; it is then, after the addition of a few drops of diluted nitric acid, completely precipitated with argentic nitrate; the precipitate is washed, by repeated decantation, and subsequently dissolved, by the aid of heat, in a solution of ammonium sesqui-carbonate. After cooling, the filtered solution is reduced by evaporation' to a small volume, and finally over-saturated with nitric acid, when argentic chloride is separated, if the bromine is contaminated with chlorine.* This test may be made at once quantitatively, by performing it with a known weight of bromine, and by collecting, drying, and weighing the precipitate of argentic chloride, and calculating the amount of chlorine contained in the quantity of the latter, on the basis of the fact that argentic chloride contains 24.13 per cent. of chlorine. Iodine is indicated by a purple coloration of carbon bisulphide, when this is shaken with a solution of the bromine in a strong solution of sodium hydrate, which has been over-saturated with fuming nitric acid previous to the addition of the carbon bisulphide. * This test depends upon the solubility of chloro-bromine in water, and the deportment of ether, which decomposes the chloro-bromine, abstracting the bromine from the aqueous solution, and leaving the chlorine as hydrochloric acid in the wa. ter, and finally upon the solubility of argentic chloride in ammonium sesqui-carbonate. CALCIUM. 167 CADMII SULPHIAS. CADMIUM SULPHURICUM. Sulphate of Cadmium. Cadmium Sulphate. Colorless, transparent, oblique prisms, containing three molecules of water of crystallization; they are efflorescent in the air, and freely soluble in water, but insoluble in alcohol. The solution has an astringent, acidulous, and slightly austere taste; it yields a white precipitate with aqua ammonike, soluble in an excess of the reagent; on subsequent addition of hydrosulphuric acid, a yellow precipitate is formed, which is soluble in strong, warm hydrochloric and nitric acids, but insoluble in diluted acids and in the alkaline hydrates (distinction from arsenious sulphide); it gives a white precipitate with the alkaline carbonates, insoluble in an excess of the precipitant. The absence of other metallic oxides may be ascertained by completely precipitating the aqueous solution of the cadmium sulphate with hydrosulphuric acid, and by subsequent complete evaporation of the filtrate; if a residue remains, admixtures of other salts are indicated. In such case, the residue should be dissolved in diluted hydrochloric or nitric acid, and examined for metallic, earthy, and alkaline oxides by the systematic method of analysis as described on pages 41-44. CALCII CARBONAS PROECIPITATA. CALCIUM CARBONICUM PRECIPITATUM. CALCARIA CARBONICA PRECIPITATA. Precipitated Calcium Carbonate. A white, light powder, consisting, when magnified, of minute rhombohedral crystals; it does not change moistened turmeric-paper, but turns it brown after having been exposed to a red heat before the blow-pipe. 168 MANUAL OF CHEMICAL ANALYSIS. Calcium carbonate is almost insoluble in water, but somewhat soluble if the water is saturated with carbonic-acid gas; the solution reddens litmus, but changes the yellow color of turmeric-paper to brown; by boiling or exposure to the air, the carbonic acid is evolved, and the calcium carbonate deposited. It is readily soluble, with effervescence, in dilute hydrochloric, nitric, and acetic acids. The acid solution is precipitated by oxalic acid, but not by a solution of calcium sulphate (distinction from barium and strontium carbonates), nor by ammonium hydrate (distinction from alumininuni carbonate), nor by potassium hydrate (distinction from magnesium carbonate). Nor must the solution yield any reaction with hydrosulphuric acid, and subsequent over-saturation with aqua ammoniae (free from carbonate). Examination: An insufficient washing in the manufacture, or a fraudulent or accidental admixture of calcium sulphate, may be detected by agitating some of the carbonate with water, and by testing the filtrate, acidulated with one or two drops of nitric acid, in separate portions, with argentic. nitrate for chloride, and with barium nitrate for sulphate. The crude kinds of calcium carbonate —chalk, prepared oyster-shells, and others derived from animal organisms-contain more or less of other bases (magnesium, iron, potassium, sodium, etc.) and acids (phosphoric, silicic, and sulphuric), and always, also, traces of organic substances; they do not render a complete solution in dilute acetic or hydrochloric acid, and the filtered solution usually gives a slight coloration or turbidity with hydrosulphuric acid, and a precipitate when over-saturated with aqua ammonise, indicating phosphates. CALCII HYPOPHOSPHIS. CALCIUM HYPOPHOSPHOROSUM. CALCIS HYPOPHOSPHIS. Hypophosphite of Lime. Calcium Hypo]phosphite. Small, colorless, transparent, six-sided prisms, or a white crystalline powder, of a pearly lustre; heated in a dry test CALCIUM. 169 tube, the salt deflagrates, emitting inflammable phosphorus vapors, and leaving a residue, which appears, after cooling, slightly reddish, being calcium pyrophosphate, with a little red phosphorus. Calcium hypophosphite dissolves in six parts of cold water, but is insoluble in alcohol (distinction from sodium hypophosphite); the aqueous solution has a slightly bitter taste, and, when greatly diluted with water, suffers no change upon the addition of diluted sulphuric acid, nor with solutions of barium and calcium chlorides, nor of plumbic acetate (distinction from soluble phosphates and phosphites); it forms, however, white precipitates with the soluble carbonates, with oxalic acid and oxalates, and with argentic nitrate, which latter precipitate soon becomes black. CALCII PHOSPHAS PR2ECIPITATA..CALCIS PHOSPHAS. CALCIUM PHOSPHORICUM. CALCARIA PHOSPHORICA. Precipitated Phosphate of Lime. Tri-basic Calcium Phosphate. A light, white, inodorous, and tasteless powder, emitting vapor of water when heated in a dry test-tube, but otherwise remaining unaltered; it fuses, without decomposition, at an intense heat. When the powder is moistened with diluted solution of argentic nitrate, it assumes a straw-yellow color. Calcium phosphate is insoluble in water, but a little soluble in water saturated with carbonic acid; it dissolves, to some extent, in acetic acid, and quite readily in diluted hydrochloric and nitric acids; the latter solution remains clear, when an excess of sodium acetate is added, and gives a copious white precipitate on the subsequent addition of oxalic acid. Examination: Ccrbonates are indicated by effervescence when a little of the calcium phosphate is first thoroughly mixed with a little water, and concentrated nitric acid added afterward. Slyhakates are detected in the diluted nitric-acid solution by a white precipitate with a few drops of barium nitrate. 170 MANUAL OF CHEMICAL ANALYSIS. Ivron and metallic salts are detected by adding hydrosulphuric acid to the nitric-acid solution, and by subsequent over-saturation with ammonium hydrate. The ensuing precipitate with the latter reagent must be perfectly white; a brown color would indicate iron; a dark one, other metals besides. CALX CHLORINATA. CALX CHLORATA. CALCARIA CHLORATA. CALCIUM HYPOCHLOROSUM. CALCARIA HYPOCHLOROSA. Chlorinated Lime. Bleaching-Powder. Calcium H.ypochlorite. A dull-white powder, with a feeble odor of chlorine, being a mixture mainly of calcium hypochlorite, hydrate, and chloride. Exposed to heat, it gives off oxygen and chlorine, and is finally converted into calcium hydrate or oxide and calcium chlorate and chloride. Mixed with ten or more parts of water, its soluble constituents enter into solution, leaving behind calcium hydrate, and the insoluble impurities of the lime employed, in the manufacture of bleaching-powder; the filtered solution is colorless, and of an acrid, nauseous taste, changes red litmus for a moment into blue, and decolorizes it almost at once, and completely; it emits the odor of chlorine with acids, and forms a white precipitate with sulphuric and oxalic acids. Chlorinated lime, exposed to the carbonic acid and moisture of the air, to acids, or to acid salts, evolves hypochlorous acid, which, when free, readily breaks up into water, chlorine, and chloric acid; the latter is also soon resolved into oxygen, water, chlorine, and perchloric acid; a deliquescent residue, consisting of calcium hydrate, carbonate; and chloride, is left of the chlorinated lime. Upon this decomposition-depends the energetic chemical action of chlorinated lime as an oxidizing agent, which, therefore, is proportionate to the percentage of calcium hypochlorite, or, in other Words, of the available chlorine. In order to estimate this, and to determine the value of commnercial bleaching-powder, several methods of testing are employed, among which the following two are simple and reliable: CALCIUM. 171 1. Seventy-eight grains of ferrous sul[1! l liphate (free of ferric oxide) are dissolved in about two ounces of water, previously boiled, and the solution is acidulated with a few drops of hydrochloric acid; it will require about 10 grains of chlorine to transform the ferrous oxide, contained in that quantity of the salt, into ferric oxide. ] lluln1e llllFifty grains of the chlorinated lime to be examined are next rubbed up with a little tepid water, and the whole transferred into a burette (Fig..52) divided into 1100 degrees, which is then filled up to 0 IIili {!] with' water, washing the mortar; after which, the contents are mixed by agitating the burette. Each degree of the mixture, therefore, contains half a grain of chlorinated lime. This liquid is allowed llllM{|ll to flow, little by little, into the ferrous solution in a beaker, with constant stirring with a glass rod, until the ferrous oxide is oxidized, which may be recognized upon a porcelain dish, or a plate of glass placed upon white paper, and provided with a number of drops of a dilute, fireshly-prepared solution of potassium fer~-~ ricyanide; the oxidation is accomplished as soon as a part of a drop of the liquid under examination, when brought in contact with one of the drops of the ferricyanide solution on the plate, ceases to cause a deep-blue coloration. The number of degrees of the solution of chlorinated lime employed is then read off: since 78 grains of ferrous sulphate require for oxidation 10 grains of chlorine, the quantity of the latter in 50 grains of the chlorinated lime may easily be calculated; thus, suppose 56 such degrees have been used for oxidation; then 172 MANUAL OF CHEMICAL ANALYSIS. Measures. Grains of Chlorine. Measures. Grains of Chlorine. 56 10 = 100 17.67 Each degree containing only half a grain of chlorinated lime, this, therefore, contains 35.34 per cent. of available chlorine. 2. 1.17 grammes of the chlorinated lime are mixed with about 6 ounces of water, to which 3.5 grammles of potassium iodide, 60 drops of concentrated hydrochlomixture the testsolution of sodim.u hyposulphite (page 63) is added, firom a burette (Fig. 53), until the appearance of a bluish tint of the mixture indicates the terminasltion of the test. If If the sample =_________ contains 30 per cent. of obtainable Ftr. 5(.3 chlorine, 100 cubic centinetres of the test-solution will be required. For instance, as 248 units (in this instance, centigrammes) of sodium hyposulphite indicate the presence of 355 units (centigrammes) of chlorine, 2.48 grammes of the former, the quantity contained in 100 cubic centimetres of the test-solution, indicate 0.355 grammes of chlorine. CARBONEUM. 173 If 100 cubic centimetres of the test-solution have been used, therefore, 0.355 grammes of chlorine is obtainable from 1.17 grammes of the chlorinated lime; and if 1.17 yield 0.355 of chlorine, 100 grammes will yield 30.35 grammes. Samples of the best commercial bleaching-powder contain, on an average, about 35 to 36 per cent. of available chlorine. CARBONEI SULPHURETUM. CARBONEUM SULPHURATUM. ALCOHOL SULPHURIS. Bisulphuret of Carbon. Carbon Bisulphide. A transparent, colorless, very volatile liquid, of great refractive and dispersive power, of a pungent, somewhat aromatic taste, and a peculiar odor, which, when pure, slightly resembles that of chloroform. Its spec. grav. is 1.27 at 15~ C., and it boils at 46.5~ C.; it burns with a blue flame, yieldinlg, as the products of combustion, carbonic and sulphurous acids; its vapor, mixed with atmospheric air, forms an explosive gas. Carbon bisulphide is not miscible with water, and sinks in it; when agitated with iodine-water, it absorbs the minute quantity of iodine dissolved in the water, and acquires a faintpurple color. Carbon bisulphide is remarkable and important on account of its extensive solvent powers; it is miscible, in all proportions, with absolute alcohol (the solubility decreasing with - the decrease of strength of the aleohol), with ether, chloroform, benzol, essential and fatty o oils; it dissolves readily and freely, among other substances, sulphur, phosphorus, bromine, iodine, iodoform, camphor, caoutchouc, gutta-percha, resins, wax, paraffin, stearin, chloral hydrate, and those alkaloids which are soluble in ether and alcohol. FIG.54. Examination: The odor of carbon bisulphide must not be repulsive, nor 174 MANUAL OF CHEMICAL ANALYSIS. fetid; it should not cause a dark turbidity or precipitate in a solution of plumbic acetate, when agitated with it, nor change the color of moist litmus-paper. An admixture of ethyl or methyl alcohol may readily be detected by the lesser density of the liquid, by its impaired property of dissolving fatty oils, and by its losing in volume when shaken, in a graduated measure, with an equal volume of water or glycerin (Fig. 54). CERII OXALAS. CERIUM OXALATUM. Oxalate of Cerium. Cerium Oxalate. A white, granular powder, without odor or taste, insoluble in water, glycerin, alcohol, ether, or chloroform, but soluble in sulphuric and hydrochloric acids. Exposed to heat, the salt is decomposed, and leaves, at a red heat, a reddish-yellow or brown residue of oxide, which is soluble without effervescence in boiling hydrochloric acid; this solution gives, with a saturated solution of potassium sulphate, a crystalline precipitate of cereo-potassium sulphate. Cerium oxalate dissolves in boiling liquor potassae, which solution, when filtered and neutralized with acetic acid, gives, with solution of calcium chloride, a white precipitate of calcium oxalate, insoluble in acetic acid, but soluble in hydrochloric acid. Examination: Earthy carbonates are indicated by effervescence of the salt with hydrochloric acid. Earthy oxalates are indicated by effervescence of the residue of the salt when reduced, at a red heat, vith hydrochloric acid. Altminium salts may be detected by boiling the oxalate of cerium with a strong solution of potassium hydrate, filtering, and adding an excess of solution of ammonium chloride, when a white, flocculent precipitate of aluminium hydrate will be formed, if such be present. CHLORALUM. 175 CHLORALI HYDRAS. CHLORALUM HYDRATUM CRYSTALLISATUM. Hydrate of Chloral. Chloral Hydrate. Colorless, semi-transparent, crystalline plates, or crystals, of a peculiar ethereal odor and pungent taste. Exposed in a dry test-tube to a gentle heat, by dipping the tube into hot water, chloral hydrate fuises at about 58~ C., and solidifies again when cooled down to 15~ C.; at about 950 C., it boils, and is partly resolved into chloral and water, which, however, combine again, and form a crystalline deposit in the cooler parts of the tube; at a higher temperature, it is wholly volatilized without combustion. Chloral hydrate is soluble in about half its weight of cold water, and freely in both alcohol and ether, but only sparingly soluble in cold chloroform, in carbon bisulphide, or in oil of turpentine. Its aqueous solution is neutral, and gives no reaction, when slightly acidulated with diluted nitric acid, with diluted solution of argentic nitrate, nor upon subsequent addition of aqua ammoni-,e; but, upon heating this mixture, decomposition takes place with effervescence, and with the formation of argentic chloride and metallic silver, the latter coating the walls of the tube. When the aqueous solution is acidulated with diluted sulphuric acid, and faintly tinged with a few drops of solution of potassium permanganate, no decoloration should take place within a few hours. Concentrated sulphuric,; nitric, and hydrochloric acids dissolve chloral hydrate with decomposition, but without color, and without the evolution of colored vapors. Solutions of the alkaline hydrates decompose it, when heated, into soluble formiates and chloroform. Ammonium sulphydrate dissolves chloral hydrate, with the evolution of heat, forming a turbid, reddish-brown liquid; the same reagent produces, in concentrated as well as in diluted solutions of chloral hydrate, a yellow coloration, which becomes dark brown, forming, with the separation -of sulphur, a reddish-brown compound, gradually when cold, immediately upon warming. 176 MANUAL OF CHEMICAL ANALYSIS. Examination: Decomposition of chloral hydrate is indicated by the issue of vapors, and by a pungent odor upon opening the vial, by the reddening of moistened blue litmus-paper, when immersed in it, and by the formation of white fumes when a glass rod, moistened with acetic acid, is held over the monuth of the vessel. It is further indicated, in the aqueous solution of chloral hydrate, acidulated with a few drops of diluted nitric acid, by a white precipitate with argentic nitrate, and in another portion, acidulated with sulphuric acid, by decoloration of solution of potassium permanganate. Cldoral aicoJholate is distinguished from the hydrate by the property of being readily and freely soluble in cold chloroform, in carbon bisulphide, or in oil of turpentine, but less soluble in cold water than is the hydrate, and by its yielding a reddishbrown or brown solution with warm concentrated sulphuric acid, and by the evolution of red nitrous vapors with concentrated nitric acid. An admixture of the alcoholate with the hydrate may be detdcted by dissolving about half a drachm of the sample in two drachmls of water; 10 drops of liquor potasse are added. and the liquid warmed to about 50~ C., by dipping the tube into water of that temperature; then, one or more drops of solution of iodinized potassium iodide are added, so as to impart to the liquid, after gentle agitation, a yellowish-brown color; it is subsequently carefully decolorized by a few drops of liquor potasse; an ensuing slight turbidity will disappear upon gentle agitation, if the cllloral hydrate be pure; but it will remain, and small yellow crystals, of iodoform (Fig. 55), altllough somewhat soluble in solutions of chloral hydrate, will subside, and be recognized under the microscopei, f ehloral alcoholate be present. The following method of approxiFIG. 55. mate estimation of the purity of chloral hydrate depends upon the volumetric determination of the quantity of chloroform produced by the decomposition of a known quantity of chloral hydrate: CHLORALUM. 177 Five hundred grains of the sample are dissolved in about one ounce of water, and the solution poured into a graduated cylinder, divided into 1,000 grain-measures (Fig. 56); the vessel wherein the solution is effected is rinsed with so much water as to make up) the solution to 700 grain-measures; 300 grainmeasures of aqua ammonio, of 0.891 spec. grav., are then added, so that the whole measures 1,000 grains. The cylinder is then closed, agitated, and immersed in tepid water, of about 50~ C., for half an' hour, the stopper being tightly fitted as soon as the expansion of the liquid, caused by the warmth, allows it; it is then set aside for 12 hours, when the fluid will have separated into two layers, a lower one of chloroform and an upper, more or less red -colored, ammoniacal aqueous solution of ammonium formniate. If the sample was pure h y- L drate, the chloroform sholll1d measure not less than 235 __ grains, equal to 351.7 grains by weight, and 70.3 per cent.' FIG. 56. of the chloral hydrate employed; if it was chloral alcoholate, the chloroform will measure about 200 grains, equal to 299 grains by weight, and to 59.8 per cent. of the chloral alcoholate. An admixture of the alcoholate with the chlorate will therefore be indicated, proportionately, by the decrease of the quantity of chloroform, ranging, in the above test, between 235 and 200 grain-measures by volumle, and 351.7 and 299 grains by weight. 12 178 MANUAL OF CHEMICAL ANALYSIS. CHLOROF 0RMUl. CHLOROFORMIUM. Chloroform. A dense, colorless, volatile, and limpid liquid, of an agreeable, ethereal, aromatic odor and sweetish taste; it does not act upon litmus, and is not readily inflammable, but, when a wick is saturated with chloroform, and ignited, it burns with a greenish flame, emitting pungent vapors which contain hydrochloric acid. It is very volatile at common temperatures, producing, by rapid evaporation, great cold, and leaving neither a residue, nor a film of moisture, nor any unpleasant odor, when wholly evaporated by the warmth of the hand, by causing the chloroform to flow to and fro, in a porcelain capsule. It boils at 610 to 620 C. Chloroform sinks in water, being but slightly soluble, one part requiring about 100 parts of water for solution. The spec. grav. of pure chloroform is about 1.50, at 15.5~ C.; in this state of purity, it is liable to decomposition by the combined action of atmospheric oxygen and of solar light; it is, however, protected against this deterioration by a slight percentage of ethylic alcohol, which is therefore retained in the preparation of medicinal chloroform, to the amount of two or three per cent., whereby its density is decreased to a spec. grav. of from 1.496 to 1.480. Chloroform is miscible, in all proportions, with absolute alcohol, with ether, benzol, carbon bisulphide, and essential and fatty oils, and is an extensive solvent for resins, caoutchouc, gutta-percha, camphor, paraffin, chloral hydrate, etc.; it also dissolves iodine, bromine, and, more or less completely, most vegetable alkaloids, which latter it almost completely withdraws from their aqueous, alkaline solutions. Chloroform is not miscible with glycerin, and is insoluble in the concentrated mineral acids; when-shaken with them, even at an elevated temperature, it undergoes no perceptible change; nor is it acted upon by the alkaline hydrates, iodides, or bromides, nor by argentic nitrate. Examination of Commercial Impure, and of Purified Chloroform: As a yreliminary test for the indication of a partial decomposition of chloroform, a test-tube may be rinsed with aqua CHLOROFORMUM. 179 ammonime, and, subsequently, one or two drops of the chloroform may be allowed to fall to the bottom of the tube; the appearance of white fumes would indicate such decomposition. In another test-tube, equal volumes of the chloroform and of water, the latter slightly blued with neutral litmus-solution, are shaken; a decoloration or a red appearance of the water, after subsiding, would likewise show decomposition. The result of these tests should also be negative, if the chloroform has been previously exposed, in a white glass bottle, to direct sunlight, for about 10 hours. Chlorine and Hydrochloric Acid.-Two volumes of chloroform are shaken in a graduated cylinder (Fig. 57) with one volume of water. A perceptible diminution of the volume of the chloroform, after subsiding, would indicate an objectionable percentaage of alcohol. The supernatant water must neither appear turbid, nor redden blue litmus-paper, nor render a precipitate when tested with dilute solution of argentic nitrate. An acid reaction upon litmus, and the occurrence of a precipitate with the latter reagent,' would indicate chlorine and hydr ochloric acid. Chlorine may also be detected by adding the chloroform, drop by drop, to a solution of potassium iodide (free from iodate) in a testtube. When agitated, the chloroform, after subsiding, will appear FIo. 5T. rose-colored, and the aqueous solution yellow, if even traces of chlorine be contained in the chloroform; when this is the case, and the addition of chloroform, in drops, is continued, each drop, falling through the laqueous solution, will assume a slight purplish tint. Ethene Chloride (Dutch Liquid).-A little fused potassium hydrate is dissolved, in a dry test-tube, in some absolute alco 180 MANUAL OF CHEMICAL ANALYSIS. hol; when the solution has subsided, the clear part is decanted into a dry test-tube, and a little chloroform added. No reaction will take place in the clear fluid, unless the chloroform contains Dutch liquid, in which case an elevation of temperature will appear perceptible by a small thermometer immersed in the liquid; a slight evolution of gas from' the liquid will also occur, and a crystalline precipitate of potassium chloride. Alcohol.-Since medicinal chloroform, as stated above, contains about two or three per cent. of alcohol, an examination for al admixture of alcohol by one of the following sensitive tests would obviously be a contradictio in adjecto. The specific gravity, the volumetric test in the preceding examination, and the property of chloroform to form a perfectly clear and transparent mixture with sweet oil of almonds, which it will not do if it contains more than five or six per cent. of alcohol, afford a sufficient evidence of the quality of chloroform in this respect. A chloroform which has a spec. grav. of less than 1.48, at 15.50 C., and which renders oil of almonds turbid, and causes a perceptible rise of temperature when suddenly shaken, in a dry test-tube, with an equal volume of concentrated sulphuric acid, cannot be considered as being of officinal strength. ests for the Detection of Alcohol in Chloroform. 1. Strong sulphuric acid, to which a little potassium bichromate has been added, when shaken with an equal bulk of chloroform, will turn green, if the latter contains alcohol. 2. Two volumes of chloroform and one volume of concentrated sulphuric acid are mixed in a bottle closed with a glass stopper; after repeated agitation, the bottle is set aside for a few hours; the liquid is then carefully diluted with about an equal bulk of water, the supernatant aqueous liquid is decanted into a beaker, and so much of a mixture of pure barium carbonate in water is added, with constant stirring with a glass rod, as completely to neutralize the acid, so that, after gentle warming, the cooled liquid does not change blue litmnus-paper; it is then passed through a moist filter, and the filtrate tested with diluted sulphuric acid. If the chloroform contained traces of alcohol, this would have given rise to the formation of ethyl CINCHONIA. 181 sulphuric acid (sulphovinic acid), and subsequently to soluble barium ethyl-sulphate, contained in the filtered solution, and which is precipitated by sulphuric acid as barium sulphate. Consequently, the occurrence of a white precipitate will be evidence of the presence of alco3. A mixture of two volumes of the chloroform with five volumes of water is warmed, in a test-tube, to about from 300 FIG. 58. to 400 C.; after violent agitation for a few minutes, the liquid is passed through a moist filter, and to the filtrate is added a little solution of iodinized potassium iodide; liquor potassue is then gradually added, until the color of the liquid disappears. After 12 hours' standing in a conical glass, a crystallinle deposit of iodoform (Fig. 58) will have taken place, if alcohol be present; the crystals may be recognized under the microscope, when the deposit is carefully removed, by.means of a small pipette (Fig. 59), from the lowest point of the conical glass, and FIG59. transferred to a glass slip. CINCHONI2E SULPHAS. CINCHONINUM SEU CINCHONIUM SULPHURICUM. Sulphate of Cinchonia or Cinchonine. Cinchonia Sulphate. Colorless, shining, oblique prisms, with dihedral summits, permanent in the air; when gently heated, in a dry test-tube, two molecules of water of crystallization are expelled, and, 182. MANUAL OF CHEMICAL ANALYSIS. upon a stronger heat, the salt fuses to a red, resinoid mass, becomes charred, and is finally completely dissipated. Cinchonia sulphate dissolves in about 56 parts of cold, and in much less boiling water, in seven parts of alcohol and in 35 parts of chloroform, and scarcely at all in ether (distinction from quinia sulphate), but it is readily soluble in dilute acids. Its aqueous solution has a very bitter taste, and exhibits no fluorescence; it is precipitated by solutions of tannic acid, potassio-mercuric iodide, potassium bicarbonate (distinction from morphia and strychnia), of barium and calcium chlorides, and of ammonium hydrate; the precipitate with the latter reagent is not dissolved by ether, when added and agitated with it; nor does aqua ammoniae cause a green reaction, when added to the solution of cinchonia sulphate in chlorine-water (distinct.ion from quinia). When concentrated sulphuric acid is poured upon cinchonia sulphate, in a dry test-tube, it dissolves it without color (distinction from salicin and brucia), and the subsequent addition of one drop of a solution of potassium bichromate produces a green coloration (distinction from strychnia). It is also dissolved without color by strong nitric acid (distinction from morphia). CODE IA. CODEINUM. codeia. Codeine. Colorless, transparent, rectangular octahedrons, which fuse at a temperature below the boiling-point of water, and, when heated upon platinum-foil, burn away without a fixed residue. Codeia is soluble in 80 parts of cold, and in 17 parts of boiling, water, and freely in acidulated water and diluted acids, and in alcohol, ether, and chloroform. When heated with less water than required for solution, or when dropped into boiling water, it sinks to the bottom, and melts. The aqueous solu COFFEIA. 183 tion of codeia has an alkaline reaction and a very bitter taste, remains unchanged upon the addition of aqua ammonie or liquor potassse, and forms precipitates with tannic acid, with iodinized potassium iodide, and with potassio-mercuric iodide. When a small portion of a cold, saturated, aqueous solution of codeia, in a test-tube, is saturated with one or two drops of diluted sulphuric acid, and warmed, it becomes turbid upon the addition of one or a few drops of liquor potassse, but is rendered transparent again upon dilution with water. Solution of codeia gives no blue reaction with ferric salts, nor does it reduce iodic acid upon addition of an iodate, nor does it suffer any coloration upon the gradual addition of concentrated sulphuric acid, and subsequent addition of a trace of potassium bichromate. Concentrated sulphuric or nitric acid dissolves codeia without coloration, and the solution in the former acid acquires a bluish tint upon the addition of one drop, or part of a drop, of a solution of a ferric salt. These characteristics of codeia are sufficient to ascertain its identity and purity. Fraudulent admixtures, like sugarcandy and crystallized salts, are at once indicated by their ready solubility in cold water, and by their insolubility in alco1hol and ether, and the latter also by a fixed residue upon incineration on platinum-foil. COFfEIA. C OFFEINUM. Coffeia. Coffeine. Theine. Guaranine. White, slender, silky needles, which contain one molecule (8.4 per cent.) of water of crystallization, and which fuse at a gentle heat, and sublime in feathery needles. When added to concentrated sulphuric acid, in a dry test-tube, coffeia dissolves, forming a colorless solution, which turns yellow upon the addition of one drop of a solution of potassium bichromate. Concentrated nitric acid oxidizes coffeia rapidly, forming com 184 MANUAL OF CHEMICAL ANALYSIS. pounds which assume a purple color when moistened with, or exposed to the vapors of, ammonia. When coffeia is added to chlorine-water, in a small porcelain capsule, and evaporated to dryness, a purple residue is left, which becomes yellow upon further heating, and red again, when moistened with, or exposed to the vapors of, ammonia. Coffeia dissolves in about 100 parts of cold, and 10 parts or less of boiling, water; the warm saturated solution separates, on cooling, most of the alkaloid; addition of dilute acids increases its solubility in water. It is freely soluble in chloroform, in 160 parts of absolute alcohol, and in about 300 parts of ether. Its aqueous solution has a bitter taste, and remains unaltered, and does not assume a purple color when it is exposed to the air, after the addition of a little aqua ammonias (distinction from phlorizin). COLCHICIA. COLCHICINUM. Colchicia. Colchicine. An amorphous, yellowish-white powder; when heated upon platinum-foil, it melts and burns away, with intumescence. Added to concentrated sulphuric acid, in a dry test-tube, it agglomerates, and, upon agitation, dissolves, with an orangeyellowish color, which soon turns yellowish-brown, but not violet (distinction from veratria); strong nitric acid, or sulphuric acid to which has been added a little nitric acid, colors it deep violet, which color passes into indigo-blue, and quickly becomes, next, olive-green, and then yellow. Colchicia is freely soluble in water (additional distinction from veratria), alcohol, and chloroform, and less so in ether. Its aqueous solution has a very bitter but not an acrid taste, becomes turbid with chlorine-water, and assumes, on subsequent addition of aqua ammonim, a yellowish-red color. CONIA. 185 CONIA. CONIINUM. Conia. Conine. A colorless, transparent, oily-looking, volatile fluid, becoming brown and darker upon exposure to warmth and air; it has a strong, penetrating odor, resembling that of a combination of the odors of tobacco and mice; its taste is acrid, somewhat like that of oil of tobacco. When dropped upon paper, conia produces, like an essential oil, only a transient stain, which by a gentle warmth entirely disappears. It burns with a bright, smoky flame. The spec. grav. of conia is from 0.88 to 0.89; when dropped upon water, it floats (distinction from nicotia). Conia combines with one-fourth of its weight of water, forming a hydrate; it is but sparingly soluble in water, one part requiring about 100 parts of cold water; the solution has an alkaline reaction, becomes turbid when warmed, turns brown when exposed to the air, and gradually deposits a brown resinous mass; it forms white precipitates with tannic acid and with potassium mercuric iodide. Conia dissolves readily in water acidulated with hydrochloric acid, and is miscible with alcohol, ether, chloroform, carbon bisulphide, and fixed and volatile oils. Conia produces white fumes with the vapors of nitric, hydrochloric, and acetic acids; when dropped into strong sulphuric acid, it dissolves without color; upon addition of one drop of a solution of potassium bichromate, a reddish-brown color ensues, which, however, quickly turns to an olive-green. Concentrated. nitric acid turns conia deep purple, and an excess of the acid produces a vehement reaction, with the evolution of nitrous acid. The alkaline hydrates do not act upon conia. Examination: The admixture of volatile or fixed oils, or of ammoniuim hydrate (which may also have resulted from gradual decomnposition), may be detected by mixing one drop of conia with 10 drops of water, upon a watch-glass or in a test-tube, and by subsequent addition of one drop of strong hydrochloric acid; 186 MANUAL OF CHEMICAL ANALYSIS. the conia should readily and wholly dissolve to a clear homogeneous solution; any turbidity or oily appearance would indicate such an admixture. It; now, about half a drop of solution of platinum chloride is added, a yellow precipitate will take place if ammonium hydrate be present. CREASOTUM. CREOSOTUM. KREOSOTUM. Ureasote. Wood-Tar Creasote. A distinction has to be made with commercial creasote between the creasote obtained from wood-tar and that derived from coal-tar; the latter is principally a mixture of impure phenol, cresol, and similar homologous alcohols, or only an impure carbolic acid, and exhibits the properties and reactions of carbolic acid (see page 78). Wood-tar creasote is a colorless, somewhat oily liquid, of a peculiar, persistent odor, resembling that of smoked meat, and of a caustic, pungent taste; it does not crystallize, nor become solid, when its temperature is lowered down to -27~ C. (distinction from coal-tar creasote); it boils at about 200~ C. Wood-tar creasote is heavier than water, and less readily dissolved therein than carbolic acid, requiring about 80 parts of cold, and 24 parts of boiling, water for solution; its solubility, specific gravity, and boiling-point, however, all vary, since creasote is not an homogeneous substance. It is miscible with alcohol, ether, chloroform, benzol, and carbon bisulphide, with anhydrous glycerin, and with fatty and essential oils; it dissolves resins, camphor, and fats, and is soluble in acetic acid; it coagulates albumen, but not collodion, mixes with concentrated sulphuric and nitric acids with decomposition, and with liquor potasse without decomposition, but is not miscible with aqua ammonie. A slip of pine-wood immersed in wood-tar creasote, and afterward in hydrochloric acid, acquires a greenish color, on CREASOTUM. 187 exposure for a short time to the air. Creasote is a powerful refractor of light; when exposed to the air and light, it does not decompose, but absorbs moisture, and becomes in time yellowish or reddish. It is combustible, and burns with a sooty flame. Examination: The admixture of volatile or Jixed oils and oily impurities may be detected when about one drachm of the creasote is agitated with three drachms of strong acetic acid; a clear solution must take place; a remaining oily layer or oily appearance would indicate such admixtures. The distinctions between wood-tar creasote and coal-tar creasote, or wood-tar creasote with an admixture of the latter, are the following: Wood-tar creasote remains liquid when cooled in a mixture of broken ice and common salt; coal-tar creasote and carbolic acid either solidify or deposit crystals at such temperatures. Wood-tar creasote, when mixed and shaken with collodion, produces a clear liquid; carbolic acid and coal-tar creasote form a kind of jelly. The aqueous solution of wood-tar creasote forms, with a few drops of neutral solution of ferric chloride or sulphate, a yellowish or yellowish-green turbidity; the solution of coal-tar creasote gives, with the same reagent, a blue or bluish-violet coloration. The same reagent, with an alcoholic solution of wood-tar creasote, gives a green coloration, and with that of coal-tar creasote, a brown one. Wood-tar creasote is not miscible with aqua ammonise fortior, while coal-tar creasote and carbolic acid are. Wood-tar creasote may also be distinguished from carbolic acid, or from coal-tar creasote containing it, by the following comparative tests: Nine drops of each sample of the creasote or Qarbolic acid to be tested are placed separately in as many small test-tubes as there are samples; to each tube is then added one drop of liquor ferric chloride, of a spec. grav. of 1.35; creasote will yield a colorless, carbolic acid a yellowish, mixture; five drops of strong alcohol are then added; creasote forms a green solution, carbolic acid a brown one; and when, finally, 60 188 MANUAL OF CHEMICAL ANALYSIS. drops of water are added, the creasote solution becomes turbid, and of a dingy-brownish color, and separates drops of creasote; while that of carbolic acid turns a beautiful blue and remains transparent, or if, at first, a few oily drops are separated, they will redissolve on agitation. CUPRI ACETAS. CUPRUM ACETICUM. Acetate of Copper. Cupric Acetate. Transparent, dark-green, rhomboidal prisms, slightly efflorescent on the surface, and emitting the odor of acetic acid when triturated or warmed with strong nitric or sulphuric acid. Cupric acetate dissolves in 14 parts of cold, and in 5 parts of boiling, water, and is also soluble in alcohol, especially when acidulated with acetic acid; its solutions have a bluish-green color, a nauseous, styptic taste, and assume, when much diluted with water, an azure-blue color upon addition of aqua ammoniae or solution of ammonium carbonate, remaining clear upon the subsequent addition of liquor potassse. The absence of iron and other impurities may be sufficiently ascertained by heating and precipitating the aqueous solution of cupric acetate with an excess of liquor sodse; when cool, the liquid is filtered; the filtrate must render no reaction with hydrosulphuric acid. On the other hand, the aqueous solution of the salt, when acidulated with hydrochloric acid, and completely precipitated with hydrosulphuric acid, must yield a filtrate which leaves no residue upon-evaporation upon platinum-foil, and does not become turbid with sodium carbonate. Cupri Subacetas.-Aerugo or verdigris is a mixture of several basic cupric acetates with various impurities; it occurs in masses of a pale-green or bluish color, and burns away when heated upon charcoal before the blow-pipe, leaving behind me CUPRUM. 189 tallic copper. When heated in a test-tube, with concentrated sulphuric acid, it emits acetic-acid vapors. Water resolves verdigris into a soluble acetate and an insoluble basic acetate; it is soluble in diluted acetic, hydrochloric, nitric, and sulphuric acids, and in an excess of solutions of ammonium hydrate or sesqui-carbonate; the insoluble remainder consists mainly of impurities, among which calcium carbonate (crude chalk) is recognized by effervescence of the verdigris with acids. For further examination, part of the solution in acid is completely precipitated with hydrosulphuric acid; the obtained filtrate must leave no residue upon evaporation, nor afford a precipitate when over-saturated with sodium carbonate; a residue and a brown precipitate would indicate iron, and also earthy admixtures. CUPRI OXIDUM. CUPRUM OXYDATUM. Blace Oxide of Copper. Cupric Oxide. A dense, black powder, when prepared by ignition of cupric nitrate, or a less dense, bluish-black, soft powder, when obtained by precipitation. It remains unaltered when heated to redness, is insoluble in water and alcohol, but slightly soluble in saliva and in the gastric juice, and readily soluble in acids; its solutions have a blue or greenish-blue color, and they assume, when so much diluted as to appear almost colorless, an azure-blue color upon addition of aqua ammonite, and a red color with potassium ferrocyanide. Examination: Cujpric nitrate and nitrite are recognized, in the oxide, by the evolution of acid nitrous vapors, when heated, in a test-tube, either dry, or with concentrated sulphuric acid; if they are not distinctly recognized by the odor, they are by their action upon moist blue litmus-paper, when held in the orifice of the tube..Metallic Imrpurities.-About 20 grains of the cupric oxide are dissolved in three drachms of warm concentrated hydro 190 MANUAL OF CHEMICAL ANALYSIS. chloric acid. A small portion of this solution is warmed in a test-tube, and completely precipitated with an excess of hydrosulphuric acid; the filtrate is over-saturated with sodium carbonate, and allowed to stand for several hours; all ensuing precipitate would indicate metallic (ferric) or earthy oxides. FIG. 60, The remaining greater portion of the hydrochlorlicacid solution may be tested for arsenic by placing it upon granulated zinc, in a large test-tube, which is then closed with a bunch of cotton, moistened with solution of plumbic acetate, and with a paper cover or a cork, provided with a strip of paper moistened with CUPRuM. 191 solution of argentic nitrate (Fig. 60). The test is then conducted as described on pages 30 to 32. A dark colora.tion of the argentic-nitrate solution would indicate arsenic. CUPRI SULPHAS. CUPRUM SULPHURICUM. SulPhate of Copper. Cupric Sulphate. Large, transparent, oblique, rhomboidal prisms of a deepblue color, containing five molecules (36.08 per cent.) of water of crystallization; they are slightly efflorescent in the air, and lose, when heated, four molecules of water at 100~ C., the fifth one being retained until a red heat, when decomposition takes place, with the evolution of sulphurous acid and of oxygen, leaving behind black oxide of copper. Cupric sulphate is soluble in four parts of cold, and in less than its own weight of boiling, water, but insoluble in alcohol; its solution has an acid reaction, a strong metallic, styptic taste, and, when diluted with so much water as to make it appear almost colorless, reassumes a blue color upon addition of aqua ammonihe; it gives a white precipitate with barium chloride, a reddish-brown one with potassium ferrocyanide, and a green one with arsenious and arsenic acids, and subsequent neutralization with liquor potassoe or sodae. Examination: Ferrous sulphate is recognized by dissolving the sulphate in diluted aqua ammoniae, or, in solutions, by adding an excess of aqua ammonite; the ferrous hydrate is precipitated along with the cupric hydrate, without being redissolved in an excess of the reagent. Traces of iron may be detected by mixing an aqueous solution of the salt with twice its volume of chlorine-water, and by the subsequent addition of aqua ammoniae; the precipitate, formed by the first addition of the ammonium hydrate, will be dissolved by a sufficient addition of the reagent, yielding a complete violet-blue solution. This is then filtered, and. when all 192 MANUAL OF CHEMICAL ANALYSIS. the liquid has passed through the filter, the latter is washed with a little dilute aqua ammoniae; a brown coating, remaining upon the filter,, would indicate traces of iron salts. 1Magnesium, Zinc, Potassium, and Sodium Sulphates.About one drachlm of the cupric sulphate, taken from a number of triturated crystals, is dissolved in two ounces of hot water, the solution is acidulated with a few drops of diluted hydrochloric acid, and, while warm, completely precipitated with hydrosulphuric-acid gas; after a few hours, it is filtered, and the filtrate evaporated to dryness; if any residue remains, it is dissolved in a little water, and divided into two portions, one of which is tested with ammonium sulphydrate, the other with a few drops of aqua ammonia and of solution of sodium phosphate; a white precipitate with the first reagent would indicate zinc, with the second one, magnesiteum. If neither of these be present, the residue can only be an allcaline sulphate. Estimation of Commercial Crude Cupric Sulphate: The following is a simple and ready mode of ascertaining the percentage of cupric sulphate contained in crude blue vitriol, some inferior kinds of which are largely crystallized together with ferrous sulphate: One hundred grains of the salt, taken from a portion of the mixed and triturated crystals, are dissolved, in a small tared beaker-glass, in about one ounce and a half of water; when necessary, the solution is filtered, and the filter washed with one or two dracllms of water; the filtrate is returned to the beaker, is acidulated with about one fluid-drachlm of concentrated hydrochloric acid, and then a piece of a thin zinc rod, about one inch long, is suspended in the solution by a very thin platinmn-wire (Fig. 61); the beaker is then allowed to stand perfectly quiet for 24 hours. -g7 After that timne, the copper will have precipitated as a bright,,-~i~-;iiiini~iamn spongy mass, around the zinc FIG. 61. rod. In order to ascertain if the precipitation has been complete, a few drops of the solution are taken by a glass rod or a pipette, and dropped into a little aqua ammoniae, or into a little hydro CUPRUM. 193 sulphuric acid acidulated with a few drops of hydrochloric acid; they will produce a blue coloration in the first instance, and a black turbidity with the second reagent, if any copper is left in solution. The copper is then carefully and completely removed from the zinc rod by means of a camel's-hair brush, and, if necessary, the apparatus is allowed, after the addition of a little diluted hydrochloric acid, to stand for 24 hours more; then, when the copper is completely abstracted from the solution, it is brushed down into the liquid, and washed from the zinc by means of a washing-bottle; the zinc is now removed, a little diluted hydrochloric acid added, and the copper allbwed to deposit; when this has taken place, the supernatant liquid is carefully removed by decantation, or by means of a pipette, and water is added and removed in the same manner as soon as the copper has subsided; this washing is repeated several times, until the water ceases to redden blue litmus-paper. Then the beaker with the copper is completely dried, and is finally weighed. The weight gives the quantity of metallic copper, and, multiplied by 3.933, the corresponding quantity of crystallized cupric sulphate, contained in 100 grains of the blue vitriol. CUPRUM AM1MlONIATUM. CUPRUM SULPHURICUM AMMONIATUM. Ammwonio-Sulphate of Copper. Ammoniated Cupric Sulphate. A deep azure-blue, crystalline powder, of an ammoniacal odor; exposed to the air, it loses gradually ammonium hydrate, and assumes a greenish appearance; this same decomposition takes place rapidly upon heating, and leaves behind basic cupric sulphate. Ammoniated cupric sulphate is soluble in one and a half part of cold water; incomplete solubility indicates partial decomposition. When the solution is diluted largely with water, it becomes turbid, and separates basic cupric sulphate, which, 13 194 MANUAL OF CHEMICAL ANALYSIS. however, is redissolved upon the addition of aqua ammonia or of acids. DIGITALINUM. Digitalin. Commercial digitalin varies somewhat in its physical properties, in consequence of different modes of preparation and different grades of purity. German digitalin, which is mostly used in tile United States, forms yellowish-white or yellowish-brown porous scales or powder, inodorous, and of an intensely bitter taste; heated upon platinum-foil, it burns off slowly, Fwith intumescence. It is soluble in water, forming a turbid, neutral liquid, which foams upon agitation; it is also soluble in alcohol, partly so in chloroform, and insolublle in ether. Its aqueous solution, when slightly acidulated with hydrochloric acid, becomes first turbid, and a flocculent white precipitate soon ensues, especially upon gentle warming. When the liquid, after several hours, is filtered off, and over-saturated with sodium carbonate, it turns blue upon the addition of one drop of dilute solution of cupric sulphate, and, when set aside, in a warm place, deposits, after a while, red cuprous oxide. When about two drops of the aqueous solution of digitalin are mixed, in a test-tube, with four or five drops of strong hydrochloric or sulphuric acid, the liquid remains at first clear, but, when immersed in boiling water, it turns successively yellow, yellowish green, and then yellowish brown, and a precipitate is formed, which, upon addition of water to the liquid, appears white, with a slightly greenish tint; the supernatant liquid shows the same color. After some time, this tint disappears, and the precipitate as well as the liquid becomes colorless. When the same test is performed with a dilute solution of sugar and with hydrochloric acid, a similar reaction takes place, but without the formation of any precipitate. I)igitain prepared by the _process of Iomnzolle and Quevenne forms either a yellowish-white powder or a white, porous, mam EMETIA. 195 millated mass, or small scales, almost insoluble in cold and warm water and in ether, but readily soluble in alcohol and in acids; it is also soluble in chloroform. If not already purified by solution in chloroform, and subsequent evaporation, as it now occurs in commerce, this digitalin, when treated with chlorofo)rm, leaves an insoluble residue behind, and the solution yields, upon evaporation, the crystallizable digitalin.* Its so]ution in hydrochloric acid is of a faint-yellowish color, but soon changes to green; upon dilution with water, it is decolorized, and digitalin separates in a resinous state. Its solution in nitric acid is at first colorless, but becomes yellow and remains so after subsequent dilution with water. Sulphuric acid dissolves it with a green color, disappearing upon dilution with water. Moistened with sulphuric acid and afterward exposed to the vapor of bromine, it assumes a violet color. EMETIA. E ME TIN U M. Emetine. Emetia. A whitish or yellowish-white, inodorous powder; heated upon platinum-foil, it melts, and burns off without residue; it is sparingly soluble in cold water and in ether, more soluble in boiling water, and freely in alcohol, chloroform, and diluted acids. The latter solutions have a slightly yellowish color and a bitter taste, and form white precipitates with tannic and gallic acids, with potassio-mercuric iodide, and with solutions of potassium, carbonate, bicarbonate, and hydrate, the precipitate with the latter reagent being soluble in an excess of the precipitant. The solution of emetia, in water acid-llated with * Recently a mode of preparing this glucoside has been devised whereby it is obtained from its solution in chloroform in fine, colorless, shining needles, intensely bitter, and, as is claimed, of a far greater physiological action; it gives an intense emerald-green coloration with hydrochloric acid, is almost insoluble in benzol and in pure ether, only sparingly soluble in water, soluble in 12 parts of alcohol, and abundantly soluble in chloroform. 1,96 MANUAL OF CHEMICAL ANALYSIS. hydrochloric acid, remains colorless upon the addition of diluted solution of ferric chloride (distinction from morphia); nor does it render any reaction with concentrated sulphuric acid, either alone or after the addition of a little potassium bichromate; concentrated nitric acid colors the solution yellowish, and, upon warming, yellowish red. FERRI ARSENIAS. FERRUM ARSENICUM. Arseniate of Iron. Ferrous-Ferric Arseniacte. When freshly prepared, an amorphous white powder, which quickly becomes green or greenish blue; when heated in a dry test-tube, it emits water-vapors, and, afterward, a crystalline sublimate of arsenious acid, leaving behind a dark residue, FIG. 62. which evolves the odor of arsenic when heated upon charcoal before the blowpipe, and gives rise to the formation of an arsenic-mirror, when heated with a little potassium cyanide, in a narrow tube (Fig. 62). Arseniate of iron is insoluble in water, but readily soluble FERRUM. -197 in warm- hydrochloric acid, forming a yellow solution, which, when highly diluted, gives a blue reaction with both potassium ferrocyanide and ferricyanide; when the solution is mixed with several times its bulk of hydrosulphuric acid, and set aside in a corked vial, in a warm place, first a white turbidity (sulphur) appears, and, after some time, a yellow precipitate. Ferrous-ferric arseniate, when boiled in a solution of sodium carbonate, yields a filtrate which, when exactly neutralized with nitric acid, gives a brick-red precipitate with argentic nitrate, and a white one with ammoniated magnesium sulphate. Examination: About one drachm of the powder is shaken with a little tepid water, and the filtrate is tested by evaporation on platinum-foil, as well as with barium chloride; neither should a fixed residue remain, nor a white precipitate be formed, as thereby an insufficient washing of the ferrous-ferric arseniate would be indicated. FERRI CARBONAS SACCHARATA. FERRUM CARBONICUM SACCHARATUM. Saccharated Carbonate of Iron, or Ferrous Carbonate. A greenish-gray powder, permanent in the air, having a sweet, feebly-chalybeate taste. Heated in a dry test-tube, it is charred, with the evolution of the vapors and odor of burning caramel. When shaken with cold water, this dissolves the sugar, and a little of the ferrous carbonate, which may be precipitated, for the most part, as ferrous hydrate, by boiling the solution; the powder is wholly and readily soluble, with effervescence, in hydrochloric acid, forming a yellow sqlution which gives, with reagents, the reactions of ferrous salts. A saccharated carbonate of iron which has a reddish color, and affords no brisk effervescence with acids, should be rejected. Examination: Sulphates may be detected by shaking a little of the pow 198 MANUAL OF CHEMICAL ANALYSIS. der with warm water, in a test-tube, and by testing the filtrate, acidulated with a few drops of diluted nitric acid, with barium nitrate; a white precipitate would indicate sulphate, left from insufficient washing in the preparation. Copper and Zinc.-The remainder upon the filter of the preceding test is digested in a test-tube, with a little solution of ammoniumn sesqui-carbonate, for about one hour. The liquid is then filtered; a bluish color of the filtrate would indicate the presence of copper, and the formation of a white precipitate, upon the addition of a few drops of ammonium sulphydrate, that of zinc. FERRI CHLORIDUX. FERRI PERCHLORIDUM. FERRUM SESQUI-CHLORATUM. Sesqui- Chloride of Iron. Perchloride of Iron. Ferric Chloride. Orange-yellow, crystalline masses, or, when obtained in the dry way, fragments having a radiate, crystalline structure, and brown color, with a metallic lustre, the former containing 12 molecules (40 per cent.), the latter, 5 molecules (22 per cent.), of water. Ferric chloride is deliquescent; when heated in a retort, it fuses at a gentle heat, giving off water; upon stronger heat, much of the chloride is decomposed, yielding ferric oxide and hydrochloric acid; part of the chloride sublimes, and condenses in the form of small, brilliant, red needles of anhydrous ferric chloride, which is very deliquescent. Ferric chloride is freely soluble in water, alcohol, and glycerin, and also, but less readily, in ether and chloroform. A strong aqueous solution, of a spec. grav. of 1.355, forms the officinal Liquor ferri chloridi. This, as well as the solution of the salt, has an acid and strongly styptic taste, and an acid reaction on test-paper; when diluted with water, they give a blue precipitate with potassium ferrocyanide, a white one with argentic nitrate, and a bulky reddish-brown one with the alkaline hydrates. FERRUXM. 199 Examination: Ferric chloride must yield a complete and clear solution in water and in alcohol; if a reddish, insoluble residue remains behind, the chloride has undergone partial decomposition. Iherrous chloride is detected, in the greatly diluted solution, by the formation of a blue precipitate with potassium ferricyanide. tFixed Impurities, other Jlietallic Chlorides, and Nitric and Sulphuric Acids.-About 20 grains of the ferric chloride, or one drachlm of the officinal liquor ferri chloridi, are dissolved in, or mixed witl, about one ounce of water. To this solution, about half an ounce of aqua ammonime is added, or so much as completely to precipitate the iron, which may be ascertained by allowing a drop of the liquid to fall upon a glass pane, on which several drops of a solution of potassium ferrocyanide have been placed. The precipitation is accomplished when the blue reaction with this reagent ceases. The liquid is then warmed to near boiling, is subsequently filtered, and evaporated to about one-fourth of its volume. It is then tested; in separate portions, for flxed imtpurities, by evaporation, and heating to redness, upon platinum-foil; for metallic impurities (copper and zinc), by mixing a portion of the solution with an equal volume of hydrosulphuric acid; for nitric acid, by mixing another part with an equal volume of diluted sulphuric acid, and by testing it, in two portions, with solution of indigo and solution of potassium permanganate; a decoloration of the faintly-colored solutions, upon gently warming, would indicate nitric acid; for sulph/uric acid, by testing another part of the solution, acidulated with a few drops of hydrochloric acid, with barium chloride. The presence of nitric acid may be confirmed by mixing a portion of the solution, or of the diluted liquor ferri chloridi, with a strong solution of ferrous sulphate, and by subsequent addition of concentrated sulphuric acid, in single drops; they will cause a dark coloration, if oxides of nitrogen be present. 200 MANUAL OF CHEMICAL ANALYSIS. FERRI CITRAS. FERRUM CITRICUM. Citrate of Iron. Ferric Citrate. Thin, transparent scales, of a garnet-red color, permanent in the air; when heated on platinum-foil, they are charred without fusing, and without the evolution of an ammoniacal odor (distinction from ammonio-ferric citrate); when coinpletely incinerated, red ferric oxide is left, which, when cool, should have no alkaline reaction upon moist turmeric or litmus paper (distinction from potassio-ferric tartrate). Ferric citrate is slowly soluble in cold, and readily in hot, water, and insoluble in alcohol; its aqueous solution has a yellow color, a mild chalybeate taste, and a neutral reaction; it is not precipitated by ammonium hydrate, and causes a deepblue turbidity when dropped into water to which a few drops of hydrochloric acid and solution of potassium ferrocyanide have been added. Examination: Ferric tartrate may be detected by completely precipitating a solution of ferric citrate with liquor potassoe, and by testing the colorless filtrate by slightly over-saturating a portion of it with acetic acid; when the solution is very dilute, it is first reduced by evaporation, and, when cold, tested with a few drops of concentrated alcoholic solution of potassium acetate; a white granular precipitate, taking. place at once or after some time, would indicate tartrate. Another portion of the filtrate is precipitated with calcium chloride, and filtered; the filtrate, when heated to boiling, should yield a white, granular precipitate of calcium citrate, which redissolves on cooling, being a confirmatory evidence of the identity of a citrate.. FERRUM. 201 FERRI ET AMMONII CHLORIDUM. AMMONIUM CHLORATUM FERRATUM. AMMONIUM MURIATICUM MARTIATUM. Ammonio- Chloride of Iron. Arnmonio-Ferric Chloride. An orange-yellow, crystalline powder, somewhat deliquescent, readily soluble in water or glycerin, and to some extent in alcohol, forming a yellow, transparent solution, which gives a copious rust-brown precipitate with alkaline hydrates, and, when very dilute, a deep-blue one with potassium ferrocyanide, and a white, curdy one with argentic nitrate. Examination: One part of the salt should render a complete and transparent solution with five parts of water; a reddish-brown insoluble residue would indicate decomposition of the ferric chloride by exposure to a too strong heat while drying the salt. Zinc and Copper.-The diluted aqueous solution is tested with potassium ferricyanide for ferrous chloride, and, when found free from it, is completely precipitated with ammonium hydrate; the filtrate is then tested with ammonium sulphydrate, which will cause a white turbidity, if zinc be present, and a brownish-black one, if copper. FERRI ET AMXONII CITRAS. FERRUM ET AMMONIUM CITRICUM. FERRUM CITRICUM AMMONIATUM. Citrate of Iron and Ammonium. Ammonio-Ferric Citrate. Thin, transparent, garnet-red scales, of a slightly-sweetish and astringent taste; they evolve, when heated, water and ammonia, and, when completely incinerated upon platinumfoil, leave behind not less than 27 per cent. of ferric oxide, which should not change the color of moist red litmus-paper (evidence of the absence of potassio-ferric salts). Heated with liquor potassoe, it evolves ammonia (distinction from ferric citrate), and deposits ferric hydrate. 202 MANUAL OF CIIEMICAL ANALYSIS. Anmmonio-ferric citrate is readily soluble in water, glycerin, and diluted alcohol, but not in strong alcohol or ether; its solution is neutral or has a slightly alkaline reaction, remains unaltered with aqua ammonie, and with solution of potassium ferrocyanide, but produces a deep-blue turbidity in very dilute solutions of the latter reagent, upon addition of mineral acids. Examination: Arnmonio-ferric tartlrce may be recognized, as asi incidental or fraudulent admixture or substitution, by completely precipitating a not too dilute aqueous solution of the salt with potassium hydrate; the liquid is heated nearly to boiling, and, when cool, filtered; one portion of the colorless filtrate is examined by slight over-saturation with acetic acid, and by subsequent addition of a little alcoholic solution of potassium acetate, and by allowing the liquid to stand for some hours; the formation of a white, crystalline deposit would indicate tartrate. Another portion of the filtrate is precipitated with calcium chloride, filtered, and the filtrate heated to boiling. A white precipitate of calcium citrate, disappearing again on cooling, will bear evidence of the identity of a citrate. FERRI ET AXMONII SUrLPHAS. FERRUM ET AMMONIUM SULPHURICUM. FERRUM SULPHURICUIM OXYDATUM AMMONIATUM. Sulphate of Iron and Ammonium. Iron Alum. Ammonio-Ferric Sulphate. Pale-violet, octahedral crystals, containing 24 molecules (44.8 per cent.) of water of crystallization;.effervescent in the air. Exposed to heat, they undergo aqueous fusion, lose the water of crystallization, swell up, and leave a pale-brown residue. When the crystals are heated with liquor potassoe, the odor of ammonia is strongly evolved. Ammonio-ferric sulphate is soluble in four parts of cold, and in less than its weight of boiling, water; it is less soluble FERRUM. 203 in glycerin, and insoluble in alcohol, ether, and chloroform. Its aqueous solution has a slightly acid reaction, a sour, astringent taste, and gives a blue precipitate with potassium ferrocyanide, a brown one with the alkaline hydrates, and a white one, insoluble in acids, with barium nitrate. When the solution of ammonio-ferric sulphate is completely precipitated with liquor potassae, the filtrate, when over-saturated with hydrochloric acid, should not render a white precipitate of alumina upon the subsequent addition of an excess of ammonium sesqui-earbonate. PERRI ET AMMONII TARTRAS. FERRUM ET AMMONIUM TARTARICUM. FERRUM TARTARICUM AMMONIATUM. Tartrate of Iron and Amnmonium. Ammonio-Ferric Tartrate. Transparent, deep-red scales, of a sweet taste, and of a rustbrown color when reduced to powder; when heated in a testtube, the salt emits vapors of water and ammonia, and, when exposed to red heat, upon platinum-foil, it is incinerated, leaving behind 29 per cent. of red ferric oxide. Heated with potassium hydrate, it evolves the odor of ammonia. Ammonio-ferric tartrate is slowly but freely soluble in water and in glycerin, but insoluble in alcohol and ether; its solution is neutral or slightly alkaline, and, when cold, is not precipitated by the alkaline hydrates or carbonates, but is so upon boiling it with either of these reagents. Its solution is not rendered blue by potassium ferrocyanide, unless acidulated. When completely precipitated by potassium hydirate, the filtrate, if not too dilute, gradually yields, after over-saturation with acetic acid, a white, crystalline deposit of potassium bitartrate. Another part of the filtrate may serve for examination for metallic impurities, by acidulating it with hydrochloric acid, and by subsequent addition of hydrosulphuric acid; a dark turbidity would indicate other metals (copper); if re 204 MANUAL OF CHEMICAL ANALYSIS. quired, the nature of the precipitate of the sulphides may be ascertained, and the metals contained therein recognized, by the method described on page 41. PERRI ET POTASSII TARTRAS. FERRUM ET POTASSIUM TARTARICUM. Tartrate of Iron and Potassium. Potassio-Ferric Tartrate. Transparent, ruby-red scales, of a sweetish and slightly astringent taste; when heated, they emit at first the odor of burning tartaric acid, and leave, upon incineration at a red heat, a residue which, when cold, blues moist red litmus-paper, and effervesces when moistened with a drop of hydrochloric acid. Potassio-ferric tartrate is freely soluble in water and in glycerin, but scarcely in alcohol; its solution is neutral or slightly alkaline, and gives, at common temperatures, no precipitate with alkaline hydrates or carbonates, nor with potassium ferrocyanide; but, upon boiling, the former, if they are added in sufficient quantity, cause a complete precipitation of the ferric oxide, and the latter gives a blue precipitate upon acidulation of the solution with mineral acids. When the filtered solution, from the precipitation with alkaline hydrate, is slightly oversaturated with acetic acid, it gives, on cooling, if not too dilute, a crystalline deposit of potassium bitartrate. FERRI ET QUINIUE CITRAS. FERRUM ET CHININUM CITRICUMo Citrate of Iron and Quinia or Quinine. Quinia Ferric Citrate. Thin, transparent scales, varying in their color from a yellowish-brown, with a tint of green, to a reddish-brown, according to the thickness of the scales. When heated, they burn FERRUM. 205 away with white fumes, and leave, upon incineration, a residue of ferric oxide, which should not change moistened red litmuspaper (evidence of the absence of alkaline citrates). Quinia ferric citrate is slowly but freely soluble in cold, and readily in hot, water, but insoluble in alcohol and ether; its solution is neutral or slightly acid, and has a bitter, mild, chalybeate taste; it gives a white precipitate of quinia with aqua ammoniae, at common temperature, and the solution assumes a deeper color; but no ferric oxide is thrown down; when the precipitate is collected upon a filter, washed with a few drops of cold water, and then dissolved in a little chlorinewater, the solution will turn emerald-green upon the addition of a few drops of aqua ammonie (evidence of the presence of quinia, and distinction from cinchonia). Solution of quinia ferric citrate gives a brown precipitate with liquor potassme or sodhe, and with aqua ammonie, when heated; a blue one with solution of potassium ferrocyanide, when acidulated with a mineral acid, and a grayish-black one with tannic acid. Examination: The absence or admixture of cheaper scaled ferric salts may be ascertained: 1. By the bitter taste, while the other scaled ferric salts have a more or less sweetish taste. 2. By the formation of a white precipitate with aqua ammonite, in the cold, while the ferric citrates and tartrates yield, with the same reagent, a brown precipitate, and the alkaline ferric salts yield no precipitate at all at common temperature. 3. By giving no odor of ammonia, nor white fumes with a glass rod, moistened with acetic acid, when heated in a testtube with liquor potassoe. Any admixture of ammonio-ferric salt would be recognized by this test. In order approximately to determine the purity of quinia ferric citrate, 50 grains of the sample are dissolved in one ounce of water, and treated with a slight excess of aqua ammonie, in the cold; the ensuing white precipitate is, after standing about half an hour, collected upon a tared filter, is washed with a few drops of very cold water, containing a slight addition of aqua ammonie, and is dried at a temperature not exceeding 80~ C.; it should weigh eight grains, and should be soluble in 206 MANUAL OF CHEMICAL ANALYSIS. six fluid-drachms of warm ether, and this solution, when set aside for 24 hours, in a corked test-tube, should not separate any crystalline deposit of the less soluble associated alkaloids of quinia (quinidia, cinchonia, and cinchonidia). PERRI PERROCYANIDUT. FERRUM FERROCYANATUM. Ferrocyanide of Iron. Prussian Blue. Ferri-Ferrocyanide. A deep-blue, tasteless powder, or hard, brittle, blue masses, showing, on the freshly-fractured surfaces, a beautiful bronzed lustre, which disappears when they are powdered. When heated, it emits colorless, inflammable vapors, and the odor of ammonia and hydrocyanic acid; exposed to a high temperature in a closed vessel, it gives off water, ammonium cyanide, and ammonium carbonate, and carbide of iron is left behind. Ferri-ferrocyanide is insoluble in water, glycerin, and alcohol, and in diluted acids, with the exception of oxalic acid, which dissolves it, with a deep-blue color. Concentrated sulphuric acid dissolves it without decomposition, forming a paste, from which the ferri-ferrocyanide may be re-precipitated by dilution with water. Concentrated hydrochloric acid decomposes it, with the formation of ferric chloride and the evolution of hydro-ferrocyanic acid. It is also decomposed by concentrated nitric acid. Alkaline hydrates and carbonates decompose it, dissolving alkaline ferrocyanide, and leaving rust-brown ferric hydrate behind. Commercial Prussian blue is not invariably pure ferri-ferrocyanide, but generally contains aluminium and potassium salts, and frequently some uncombined ferric hydrate. These impurities may be detected by boiling the triturated Prussian blue with dilute hydrochloric. acid, and precipitating the filtrate with ammonium hydrate, when alumlinium hydrate and ferric hydrate are precipitated, while pure ferri-ferrocyanide, treated in this manner, yields no precipitate. If the precipitate has to FERRUM. 207 be examined for aluminium salts, it is collected upon a filter, washed, and treated with warm liquor potassoe; a few drops of this filtrate, allowed to fall into a solution of ammonium chloride, will indicate aluminium salts by a white precipitate. Examination: Mltnera7l Admixtures.-About half a drachm of the ferriferrocyanide is heated, in a porcelain crucible, to redness; when cool, the residue is dissolved in concentrated lydrochloric acid, and should render a complete and clear solution, with slight effervescence; a residue would indicate fixed mineral admixtures (calcium or barium sulphates). _Metals. —To the solution obtained in the preceding test, a little potassium chlorate is added, and the solution boiled until the odor of chlorine ceases; it is then diluted, filtered, and tho filtrate divided into two portions; these are heated, and the one is precipitated with liquor potassm, the other with aqua ammoniion; after a while, they are filtered, and each of the alkaline filtrates is tested with ammonium sulpblydrate; a black precipitate, in the potassium-solution, would indicate lead; a brownish-black precipitate and a blue coloration, in the ammoniacal liquid, copper; a white turbidity; in either of the liquids, shows zinc to be present. Earthy Carbonates. —The ammoniacal liquid of the preceding test, regardless of the result of the test, is filtered, and tested with sodium carbonate; an ensuing white precipitate would indicate carbonates of lime, barium, or mnagnesia. PERRI HYPOPHOSPHIS. FERRUM HYPOPHOSPHOROSUM. fypophosphite of Iron. Ferric Hypophosphite. A yellowish-white, odorless powder; when heated, in a dry test-tube, it gives off inflammable phosphorous vapors, with considerable intumescence, leaving behind ferric pyrophosphate. Since hypophosphorous acid is very prone to absorb 208 MANUAL OF CHEMICAL ANALYSIS. oxygen, the salt is readily decomposed by all oxidizing agents. Ferric hypophosphite is insoluble in cold water, but soluble in diluted hydrochloric acid, forming a yellow solution, which, when greatly diluted, gives a blue precipitate with potassium ferrocyanide; it is readily soluble in solutions of ferric sulphate and of sodium hypophosphite. FERRI IODIDUX. FERRUM IODATUM. Ferrous Iodide. Opaque plates or masses, of an iron-gray color, metallic lustre, and crystalline fracture. When heated in a dry testtube, ferrous iodide fuses, and emits violet iodine vapors, finally leaving behind ferric oxide. Ferrous iodide is very deliquescent; it is soluble in its own weight of water, and also in alcohol and glycerin, forming yellowish-green solutions, with a styptic taste; its aqueous solution gives a copious blue precipitate with potassium ferricyanide, and acquires a blue color upon addition of a little mucilage of starch, and, afterward, of a minute quantity of chlorine-water. Ferrous iodide and its solutions rapidly oxidize, the latter forming a rust-brown sediment, the former becoming less soluble in water, and yielding a brown solution, one drop of which, when added to a few drops of chloroform, and subsequently shaken with some water, colors the chloroform light carmine-red, which is not the case when the ferrous iodide is fresh, and not yet partly oxidized. Ferrous iodide is decomposed by, and therefore incompatible with, acids, the alkaline hydrates and carbonates, and those metallic salts which form insoluble iodides. The oxidation of ferrous iodide is greatly obviated by its mixture with sugar. Upon this fact, the preparation of FERRI IODIDUM SACCHARATUM and of SYRUPus FERRI IODIDI are based; both share the chemical properties and reactions of the ferrous FERRUM. 209 iodide. The syrup may be preserved without decomposition, when kept in a sunny place, in small, well-corked vials, containing a piece of clean, bright iron wire, or when a few grains of tartaric or citric acid are added for each ounce, and the whole kept in simall, well-corked vials. PERRI LACTAS. FERRUM LACTICU3I. Lactate of Iron. F'errous Lactate. Greenish-white, crystalline crusts or grains, or a greenishwhite powder; * when heated, the salt froths up, with the evolution of white, acid, inflammable fumes, and becomes black, and, when completely incinerated, ferric oxide is left behind, which, when cold, should not act upon moist red litmus-paper (evidence of the absence of alkaline salts). Ferrous lactate is soluble in about 48 parts of cold, and 12 parts of boiling. water, and almost insoluble in alcohol; its aqueous solution is more or less turbid and of a yellowish-green color, and has a mild, sweetish, chalybeate taste; when filtered and diluted, it gives a rust-brown precipitate with the alkaline hydrates, and a blue one with potassium ferrocyanide, and yields a white, granular deposit of mucic acid, on cooling, when boiled for fifteen minutes with nitric acid; plumbic acetate should cause, in a solution of ferrous lactate, only an opalescence (evidence of the absence of sulphuric, hydrochloric, tartaric, citric, and pomic acids). X The ferrous lactate of the German manufacturers and shops occurs as a yellowish or grayish-green powder, and is obtained by the following process, which is least subject to the formation of peroxide: An alcoholic solution of socdium lactate is exactly decomposed by a concentrated aqueous solution of ferrous chloride. Allowed to stand for 24 hours, in a filled and closely-stoppered bottle, in a cool place, the ferrous lactate separates in a thick, crystalline crust, which, after the menstruum has been removed, is broken by a wooden spatula, and then transferred to a cloth wvashed with a little alcohol, and afterward subjected to a moderate pressure, under a small screw-press. The resulting salt cake is broken, and dried at a gentle warmth, and finally triturated. 14 210 MANUAL OF CHEMICAL ANALYSIS. Examination: Mineral Im~purities.-About half a drachm of the ferrous lactate is completely incinerated in a porcelain crucible, or upon an iron spoon; the remainder is extracted with boiling water; the filtrate must neither act upon test-paper, nor leave any residue upon evaporation on platinum-foil. The insoluble residue is then agitated with a little warm diluted acetic acid, the liquid filtered, and a little chlorine-water added; it is then precipitated with aqua ammonioe, and afterward filtered. The filtrate is examined with a few drops of a solution of sodium phosphate; a white turbidity would indicate magnesium salts. Gummi, Dextr;in, Sugar of 3ilk.-About 20 grains of the ferrous lactate are dissolved in one ounce of warm water, and subsequently precipitated by an excess of liquor sodre; after warming and shaking, the precipitate is filtered. off, and a few drops of a solution of cupric sulphate are added to one portion of the filtrate; the ensuing turbidity must completely redissolve on agitation; a remaining white coagulation would indicate gummzi; if this be the case, the solution is filtered, and heated to near boiling; an ensuing red precipitate would indicate sugar of milk. An excess of concentrated sulphuric acid is added to the rest of the first alkaline filtrate. and the whole evaporated almost to dryness, upon a porcelain capsule, at a temperature not exceeding 100~ C. A black, more or less charred, residue would confirm the presence of either gummi or sugar, or both. PERRI OXIDUlI HYDRATUM. FERRI PEROXIDUM HYDRATUM. FERRUM OXYDATUM RUBRUM. CROCUS MARTIS ADSTRINGENS. Hydrated Oxide of Iron. Peroxyhydrate of Iron. Ferric Hydrate. A reddish-brown, tasteless powder, destitute of grittiness; when heated in a dry test-tube, it emits moisture, but no acid vapors; it is slowly but wholly soluble, without effervescence, in warm hydrochloric acid diluted with half its volume of wa FERRUM. 211 ter, forming a yellow solution, which, when diluted with water, gives only a white turbidity with hydrosulphuric acid, and a blue precipitate with potassium ferrocyanide, but no reaction with ferricyanide; when completely precipitated by alkaline hydrates, the filtrate should be colorless, and should render no reaction either with ammonium sulphydrate or with sodium carbonate (evidence of the absence of zinc, magnesium, and calcium). Examination: Alkal'ine sulvphates may be detected by agitating the ferric hydrate with a little warm water, and acidulating the filtrate with one drop of hydrochloric acid, and testing it with barium chloride. CoPyper may be detected by a blue coloration of solution of ammonium sesqui-carbonate, when agitated with the ferric hydrate, and subsequently filtered; its presence may be confirmed or recognized, when the result of the preceding test is uncertain, by over-saturating the filtrate with acetic acid, and testing it with potassium ferrocyanide; a reddish-brown precipitate would indicate or confirm copper. PFERRI OXIDUM XAGNETICUYX. FERRI OXIDUM NIGRUM. FERRUM OXYDULATO-OXYDATUM. ATHIOPS MARTIALIS. Black Magnetic Oxide of Iron. Ferro-Ferric Hydrate. A brownish-black or black powder, destitute of taste, and attracted by the magnet; heated in the air, it giws off water, absorbs oxygen, and forms red ferric oxide. It dissolves readily and completely, without effervescence, upon warming, in a mixture of equal parts of water and hydrochloric acid, forming a yellowish solution which gives a blue precipitate with both potassium ferrocyanide and ferricyanide, and a white turbidity with hydrosulphuric acid. 212 MANUAL OF CHEMICAL ANALYSIS. Examination: Alkaline Stlphactes or Ch/orides.-About one drachm of the f'erro-ferric hydrate is shaken with about four drachms of warm water; the filtrate, when evaporated upon platinum-foil, must leave no fixed residue, nor yield, when acidulated with a few drops of'acetic acid, any white precipitate with barium chloride or with argentic nitrate. Jfetals. —The remaining ferro-ferric hydrate from the preceding test is boiled in a flask with some dilute liquor potassue; when cold, the mixture is filtered, and is subsequently saturated with hydrosulphuric-acid gas, or else some sodium-sulphide solution is added: an ensuing black precipitate would indicate lead, a white one, zince; if no reaction takes place, the liquid is over-saturated with hydrochloric acid; a slight white turbidity (sulphur) xwill occur; a yellow precipitate would indicate arsenic, an orange one, antimony. The remaining ferro-ferric hydrate, left behind from its treatment with liquor potassue, is washed, and then digested for some hours with a little strong aqua ammonioe; when filtered, the filtrate will have a bluish tint, and give a dark turbidity upon the addition of a few drops of ammonium sulphydrate, if coppper be present. FERRI PHOSPHAS. FERRUM PHIOSPHORICUM. FERRUM OXYDULATO-OXYDATUM PHOSPHORICUM. Phosphate of Iron. Ferrous-Ferric Phosphate. A fine, amorphous powder, of a slate-blue color when cold, and grayish green when hot; heated in a dry test-tube, it gives off water, and leaves a black residue; it is insoluble in water, but soluble in the mineral acids, forming yellow solutions, which, when highly diluted, yield a blue precipitate with both potassium ferricyanide and ferrocyanide, and a white turbidity of sulphur with hydrosulphuric acid. When ferrousferric phosphate is boiled in a solution of' sodium carbonate, and filtered, a filtrate is obtained which, when neutralized with acetic acid, gives a yellow precipitate with argentic nitrate, FERRUM. 213 and a white one with ammoniated solution of magnesium sulphate. Examination: Sodium sulphate, left from insufficient washing, may hbe detected, when a little of the powder is shaken with some hot water, and the filtrate tested with barium chloride..etal&.-A strong solution of the powder in hydrochloric acid is mixed with a comparatively large volume of hydrosulphuric acid, and set aside for at few hours, in a closed flask, in a warm place; a slight white turbidity (sulphur) will occur; a dark one would indicate copper, a yellow one, arsentic, which FIG. 63. latter can be confirmed by the odor when a little of the salt is heated upon charcoal, before the blow-pipe, or by the formation of a metallic mirror, in a narrow tube, upon heating the dried precipitate with potassium cyanide (Fig. 63). FERRI PYROPHOSPHAS. FERRUM PYROPHOSPHORICUM. Bi-basic Phosphate of Iron. Ferric Pyrophosphate. A white, tasteless powder; when heated in a dry test-tube, it loses moisture, but remains white, and decreases in volume. 214 MANUAL OF CHEMICAL ANALYSIS. It is insoluble in water, but soluble in hydrochloric acid, and in solutions of sodium pyrophosphate and of alkaline citrates. When boiled with a solution of sodium carbonate, ferric pyrophosphate assumes a reddish-brown color, and yields a filtrate of the same tint, but which becomes almost decolorized upon slight over-saturation with acetic acid, and which gives a dense, white precipitate with argentic nitrate (distinction from ferric phosphate, which gives a yellow precipitate, and from ferric metaphosphate, which gives a white gelatinous one). FERRI PYROPHOSPHAS ET AMMONII CITRAS. FERRUM PYROPHOSPHORICUM CUM AMiMONIO CITRICO. Pyrophosphate of Iron with Citrate of Ammoniumn. Ammoniated Pyrophosphate of Iron. Pyrophosphate of Iron in Scales. Thin, apple-green, transparent scales, of a mild, acidulous, and saline taste: freely soluble in water or glycerin, but insoluble in alcohol; by exposure to the air, the scales lose their transparency and solubility in water; the latter, however, may I)e restored by the addition of aqua ammoniae. The solution is not precipitated either by acids or by ammonium hydrate, but gives a yellowish-white precipitate, with the evolution of ammonia, when boiled with liquor potassoe, and a dense white precipitate, when acidulated with acetic acid, and tested with argentic nitrate. Potassium ferrocyanide, when added to the dilute solution of the salt, occasions a pale-blue color, but produces no precipitate. FERRI SUBCARBONAS. FERRUM HYDRICUM. FERRUM OXYDATUM FUSCUM. FERRUM SUBCARBONICUM. CROCUS MARTIS APERITIVUS. Carbonate of Iron. A fine, amorphous, reddish-brown powder, without odor or taste; when heated in a dry test-tube, it emits watery vapors, FERRUM. 215 which condense in the cooler parts of the tube, and which, when tested with blue litmus-paper, should not alter its color. Carbonate of iron is insoluble in water, but readily and freely soluble, with slight effervescence, in warm, diluted hydrochloric acid, forming a yellow solution, a few drops of which, when added to water, impart to this the property of yielding a blue precipitate with both potassium ferrocyanide and ferricyanide. The solution therefore affords, with reagents, the reactions of both ferrous and ferric salts. Examination: Ferri Subcarbonas is distinguished from Ferri Oxidum Hydratum by its reddish-brown color, by its readier solubility in hydrochloric acid, by effervescence with acids, and by its reaction with potassium ferricyanide. &Sodium or Ammoniumr Sulphate.-About 10 grains of the powder are agitated, in a test-tube, with about two drachms of warm water; the filtrate should leave no residue upon evaporation on platinum-foil, nor should it render a white turbidity with barium nitrate. Aetals. —The undissolved ferric hydrate remaining upon the filter, in the preceding test, is digested with solution of ammoniumn sesqui-carbonate for one or two hours; the subsequent filtrate, when tested with a few drops of ammonium sulphydrate, would show copper by a bluish tint of the liquid, and zinc by a white precipitate. FERRI SULPHAS. FERRUM SULPHURICUM. Sulphate of Iron. Ferrous Sulphate. Transparent, oblique-rhombic prisms, of a pale bluish-green color and salty, styptic taste, or, whebn obtained by precipitation, by means of alcohol, a pale-green, crystalline powder (Ferri Sulphas granulatC). The crystals are efflorescent in the air, and absorb oxygen; when heated, they undergo aqueous 216 MANUAL OF CHEMICAL ANALYSIS. fusion; they contain seven molecules (45.56 per cent.) of water of crystallization, six-sevenths of which they lose at a moderate heat, leaving a greenish or grayish white powder (FI'erri SOlphas exsiccata). At a red heat, the seventh molecule of water, and also the acid, is expelled, leaving behind red, anhydrous, ferric oxide (Caput Jlortzum). One hundred parts of water, at 10~ C., dissolve 61 parts, at 25~ C., 103 parts, and, at 1000 C., 280 parts, of crystallized ferrous sulphate; it is insoluble in alcohol; its aqueous solution has a slight acid reaction, readily absorbs oxygen, and becomes. turbid by the formation of an insoluble basic ferric sulphate, while a neutral ferric sulphate remains in solution, with the undecomposed ferrous sulphate. The solution of ferrous sulphate, when greatly diluted, gives a white precipitate with barium chloride, a blue one with potassium ferricyanide, and, when not yet oxidized, a white one with the ferrocyanide; it renders no precipitate with hydrosulphuric acid. Examination: fPetals.-About one drachmn of the crystals is dissolved in about two drachms of boiling water, acidulated with a few drops of sulphuric acid; the solution is then added to about 1ounce of hydrosulphuric acid, in a stoppered 2-ounce vial, and shaken; after several hours, only a white turbidity (sulphur) should have been formed; a dark turbidity would indicate copper, and perhaps other metals. The liquid is then filtered, and evaporated, in a porcelain capsule, until all odor ceases; when this is the case, about half a drachm of concentrated sulphuric acid and 20 drops of concentrated nitric acid are added, and the whole evaporated nearly to dryness. The residue is dissolved in water, and aqua ammonim added with constant stirring, until the ensuing precipitate ceases to be redissolved; then from four to five drachms of Liquor Ammonii Acetici are added, the whole heated to boiling, and filtered while hot. An excess of aqua ammonia is then added to the colorless filtrate, and, if any more precipitation occurs, it is once more filtered, and subsequently tested with ammonium sulphydrate; an ensuing white turbidity would indicate zinc, a reddish-white one, ~manyganese. Finally, the liquid, after having been filtered, if such reactions have occurred, is tested with ammonium phos FERRUM. 217 phate; a crystalline, white precipitate, occurring after some time, would indicate mnagnesia. Crude commercial sulphate of iron is generally considerably contaminated with metallic and earthy salts, and not fit fbr medicinal use; it contains, besides, the sulphates of zinc, aluminium, and magnesium, and generally so much sulphate of copper as to deposit a metallic cupreous film upon a bright blade of an iron knife or spatula, when immersed for some hours in the aqueous solution, acidulated with a few drops of sulphuric acid. FERRI VALERIANAS. FERRUM VALERIANICUM. falerianate of Iron. Ferric Valerianate. A dark, tile-red, amorphous powder, or thin, reddish scales, having the faint odor and taste of valerianic acid. When heated in a porcelain capsule, the salt melts, emits inflammable vapors, and, when incinerated, leaves behind ferric oxide, which should not color moistened turmeric-paper brown, nor dissolve in warm dilute acetic acid. Ferric valerianate is soluble in alcohol (distinction from citrate and tartrate of iron), but insoluble in water; boiling water decomposes it, extracting the valerianic acid, and leaving the ferric hydrate behind; the filtrate is colorless, reddens litmus-paper, and gives no reaction with ammonium hydrate and subsequent addition of hydrosulphuric acid. Acids decompose ferric valerianate, forming soluble ferric salts, and setting free the valerianic acid. Examination: Admixtures of ferric tartrate or citrate, impregnated with oil of valerian, may readily be recognized by their solubility in water and insolubility in strong alcohol; the latter dissolves' only the oil of valerian, if such be present, readily recognized by its odor, when a portion of the alcohol is evaporated upon the warm hand. 218 MANUAL OF CHEMICAL ANALYSIS. Iron. The source of the medicinal preparations of iron is the refined malleable wrought-iron, of which the piano-forte wire is among the best commercial varieties. When iron filings or turnings are employed instead of wire, care has to be taken that they are not derived from crude cast or pig iron, that they are free from rust, and that they are not contaminated with copper or brass filings from the workshops. Cast or pig iron may be recognized by the evolution of gas of a noxious odor, and by a considerable black residue, when the filings or turnings are dissolved, in a test-tube, in a mixture of equal parts of concentrated hydrochloric acid and water. An admixture of copper or brass filings may be recognized, with approximlate certainty, by close inspection, with a magnifying-glass, and by chemical tests, as hereafter described. In the preparation of solutions of iron, which are subsequently filtered, filings of cast-iron are not exactly objectionable; iron filings or turnings, however, which may contain, or are liable to contain, copper or brass filings, ought not to be employed for medicinal preparations, since copper is dissolved by acids, notwithstanding an excess of iron. FERRUTM PULVERATUM.-A fine, gray powder, of a dull, metallic appearance; when heated to redness, it oxidizes, forming a reddish powder, and increasing in weight, if the powder employed was pure and dry. Iron powder dissolves in a mixture of equal parts of hydrochloric acid and water, evolving impure hydrogen gas, of a faint odor, and leaving only a small insoluble black residue; the filtered solution has a light-green color, and affords, when greatly diluted with water, a deepblue turbidity with potassium ferricyanide, and almost white precipitates with the alkaline hydrates and carbonates, which, however, rapidly oxidize, and become green, and ultimately brown. FERRUM REDUCTUM.-Iron powder, obtained by reduction of ferric oxide or oxy-hydrate by hydrogen, at a strong heat, forms a very fine, black powder, which reoxidizes when heated FERRUM. 219 to redness, and which is readily and wholly soluble in warm diluted hydrochloric acid, with the evolution of pure hydrogen gas, forming a solution which has the same properties and deportment with reagents as that of powdered iron. If the solution takes place without a copious evolution of gas, and has, when filtered, a yellowish appearance instead of a light-green one, the powder was more or less oxidized, or even so miuch so as to consist almost wholly of a mixture of ferrous and ferric oxides. Examination of Iron: Sulphur may be recognized by the black coloration of a solution of plumbic acetate, when a little of the iron is dissolved in a mixture of equal parts of hydrochloric acid and water, either in a test-tube, loosely closed with a bunch of cotton moistenedwith solution of plumbic acetate (Fig. 29, page 72), or in a small flask (Fig. 64), whence the evolved gas is passed through a solution of plumbic acetate in a test-tube. If the plumFIG. 64. bic solution in either case becomes black, sulphur is indicated. Sulphur, phosphorus, and arsenic, may be detected, in iron powder, filings, turnings, or wire, by submitting about 100 FIG. 65. 220 MANUAL OF CHEMICAL ANALYSIS. grains of the iron, in a generating-flask, a (Fig. 65), to the action of about one ounce, or a little more, of a mixture of equal parts of concentrated hydrochloric acid and water, and by passing the evolved gas through a dilute solution of cadnium sulphate in c, and through a dilute solution of argentic nitrate, contained in d. The acid is, little by little, added to the iron, through the fiunnel-tube b, so that the evolution of the gas and its passage through the fluids are slow. The solution in c is prepared by adding to an aqueous solution of cadriiuin sulphate (1:100) so much of ammonium hydrate as is required to redissolve the precipitate, formed upon the first addition of the alkaline hydrate. The occurrence of a yellow precipitate in the cadmium solution would indicate sulzphr, and of a black one in the argentic solution, arsenic or phosphorus. In order to distinguish either arsenic or phosphorus, or both, in the iron, the blackened argentic solution is warmed, and completely precipitated with hydrochloric acid; when cool, it is filtered and the filtrate mixed with an equal volume of hydrosulphuric acid, and allowed to stand, in a corked vial, for several hours; an ensuing yellow precipitate would indicate arsenic; the liquid is then filtered, and boiled in a porcelain capsule, until it becomes odorless; it is then over-saturated with aqua ammoniae, filtered, and tested with solution of ammoniated magnesium sulphate; a white precipitate would be indicative of the presence of phosphorus in the iron. Mzetallic Impurities.-Zinc may be detected in the solution obtained in the generating-flask of the preceding test, by filtering it, and by evaporation of the filtrate to dryness, after the addition of a little nitric acid; the residue is extracted by boiling it with liquor potassse, and the filtered liquid, when cool, is tested with sodium sulphide; a white precipitate would indicate zinc. Copper and lead may be detected in the iron, by treating it with warm diluted nitric acid, and by testing part of this solution with a few drops of a solution of sodium sulphate for lead, and by evaporating another part of the solution to dryness, and subsequently digesting the residue with an excess of aqua ammonike; a blue coloration of the filtrate would indicate copper. GLYCERINUM. 221 GLYCERINUM. GLYCERINA. Glycerin. Triatomic Propenyl Alcohol. A colorless and odorless, thick, viscid, neutral liquid, of an intensely sweet taste; when anhydrous, its spec. grav. is 1.267; that of commercial glycerin, containing from 10 to 4 per cent. of water, is from 1.22 to 1.25. Glycerin is not volatile at common temperatures, but distils unchanged, with water-vapor, under pressure; it boils at 290~ C., and decomposes at a temperature a little above its boiling-point. Exposed to a strong heat, on platinum-foil or in a porcelain capsule, it emits white, irritating, inflammable vapors, which burn with a blue flame, leaving, finally, a black residue, which, however, is completely dissipated at a red heat. Glycerin is miscible, in all proportions, with water, aqua ammonite, liquor potassoe, alcohol, and ether diluted with alcohol, but not with pure ether, chlorofornm, carbon bisulphide, or benzol; it mixes with concentrated sulphuric acid without change, but suffers decomposition with concentrated nitric and hydrochloric acids. Glycerin possesses extensive powers as a solvent; it dissolves most substances which are soluble in water, although in a less degree, but is a better solvent for bromine, iodine, and carbolic acid. It does not mix with fatty oils, and dissolves essential oils only to a limited extent. Examination: A fatty or empyreumatic odor of glycerin is recognized by the smell, especially upon gently warming.a little of the sample on a watch-glass or porcelain capsule. Sugar, glucose, and mucilages, are indicated by a more or less brown coloration of the glycerin, when mixed with twice its bulk of concentrated sulphuric acid, or when mixed and heated with a strong solution of potassium hydrate. Glucose may be detected by the occurrence of a brick-red precipitate, when a mixture of equal volumes of the glycerin and of liquor potassam, with two or three drops of solution of cupric sulphate, is heated in a test-tube. 222 MANUAL OF CHEMICAL ANALYSIS. Sugar is detected by the same reaction, when the glycerin is boiled for a few minutes with an equal volume of very ditute solution of tartaric acid, and the hot mixture tested with Fehling's cupric solution. MJilucilages of gum, dextrin, or glue, are indicated by the formation of a white turbidity, gelatinous, or flocculent, when one volume of the glycerin is mixed with four volumes of alcohol. iMetallic salts are detected by agitating one volume of the glycerin with three volumes of hydrosulphuric acid; any impairing of the colorlessness or transparency of the mixture would indicate metallic impurities; they may be distinguished, as to what group of metals they belong to, by dividing the liquid into two portions, and adding to the one a little hydrochloric acid, and to the other aqua ammonite. Copper, lead, and tin, will be indicated by the first test; iron, zinc, and aluminiuzn, by the second. If a precipitate appears in either case, and the nature of the impurity has to be ascertained, the test must be repeated on a larger scale, and the metallic impurity be determined in the mode described on pages 41 to 44. Calcizum salts may be detected in the diluted glycerin, by a white turbidity when tested with ammonium oxalate. Acids and their Salts.-When diluted with twice its volume of'water, the solution must leave litmus-paper unchanged; it is then examined in four separate portions: for hydrochlotic acid and chlorides, by acidulating with nitric acid, and testing with argentic nitrate; for sulphuric acid and sulphates, by testing the second portion, also acidulated with nitric acid, with barium nitrate; for oxalic acid, by testing the third portion, acidulated with acetic acid, with calcium acetate; and for nitric acid and nitrates, by adding to the fourth portion a little acetic acid and one drop of neutral indigo-solution, and then warming the mixture by dipping the test-tube into hot water; a decoloration of the bluish or bluish-green tint of the liquid will indicate free nitric acid; when the color remains unaltered, a few drops of concentrated sulphuric acid are added to the mixture while still warm; if decoloration takes place now (and the glycerin is free from chlorides and chlorates), nitrates are indicated. GLYCERINUM. 223 Another very sensitive test for nitric acid and nitrates, combining the test for chlorine, is to mix, in a test-tube, about one fluid-drachm of sulphuric-acid mucilage of starch with a few drops of solution of potassium iodide (free from iodate), and then to add about one fluid-drachm of glycerin; when mixed together with a glass rod, the liquid must remain colorless; a blue color would indicate chlorine; when the mixture remains colorless, a thin rod of bright zinc is immersed in the centre of the fluid, with care not to agitate the test-tube; if traces of nitric acid or nitrates be present, a bluish coloration, issuing from the zinc, will appear. Formiic acid may be detected by the formation of a black deposit, when a mixture of the glycerine with an equal volume of diluted aqua amronite and a little solution of argentic nitrate is allowed to stand in a corked test-tube, protected from the light, for 24 hours. Butyric acid, and analogous fatty acids, may be recognized by the odor of ethyl butyrate (similar to that of artificial essence of pine-apple), when a mixture of two volumes of glycerin with one volume of a mixture of equal parts, by volume, of strong alcohol and concentrated sulphuric acid, is gently warmed by dipping the flask or test-tube into boiling water. FIG. 66. Ammonium salts, occasioned by the neutralization of an originally slightly acidulous glycerin with aqua aimmoniae, may 224 MANUAL OF CHEMICAL ANALYSIS. be detected by heating the glycerin in a large test-tube, half filled with it, and provided, by means of a rubber cork, with a delivery-tube reaching to the bottom of a receiving test-tube which contains a little water, and is cooled in ice-water (Fig. 66); the generating tube or flask, containing the glycerin, is immersed, for about half an hour, in a boiling concentrated solution of culinary salt; after that time, the contents of the recipient are tested with red litmus-paper, which should not be altered thereby, and are then divided into two separate portions; a few grains of dry potassium hydrate are dissolved in the one portion; upon heating it, ammonia will be recognized by the odor, and by white vapors when a glass rod moistened with acetic acid is held at the orifice'of the tube; to the other portion, a few drops of liquor potassse and, subsequently, one or two drops of solution of potassiomercuric iodide are added; a yellowish-brown precipitate or coloration would afford an additional indication of ammnoniuln salts. T A BLE OF THE QUANTITY BY WEIGHT OF WATER CONTAINED IN 100 PARTS BY WEIGHT OF GLYCERIN AT DIFFERENT DENSITIES. TEMPERATURE 1T.5~ C. Specific 2 Specific r. Specific Specific Specific Gravity. Gravity. Gravity. Gravit. 1.267 0 1.224 13 1.185 26 1.147 39 1.264 1 1.221 14 1.182 27 1.145 40 1.260 2 1.218 15 1.179 28 1.142 41 1.257 3 1.215 16 1.176 29 1.139 42 1.254 4 1.912 17 1.173 30 1.136 43 1.250 5 1.209 18 1.170 31 1.134 441 1.247 6 1.206 19 1.167 32 1.131 4e 1.244 7 1.203 20 1.164 33 1.128 45 1.240 8 1.200 21 1.161 34 i 1.126 47 1.237 9 1.197 22 1.159 35 1.123 48 1.234 10 1.194 23 1.156 36 1.120 49 1.231 11 1.191 24 1.153 37 1.118 50 1.228 12 1.188 25 1.150 38 HYDRARGYRUM. 225 HYDRARGYRI CIHLORIDUM CORROSIVUIM. HYDRARGYRI PERCHLORIDUM. HYDRARGYRUM BICHLORATUM. HYDRARGYRUM CORROSIVUM SUBLIMATUM. Corrosive Sublimate. Perchloride or Bichloride of HMercury. Mereuric Chloride. Colorless, translucent, heavy, crystalline masses, when obtained by sublimation, or small, prismatic crystals, when obtained by crystallization, of a spec. grav. of 5.43; they are permanent in the air, give a dull, white streak when scratched with a knife, are slightly volatile at common temperatures, fuse at 265~ C., and volatilize wholly at 295~ C., forming dense, white vapors, which, on cooling, solidify in small, shining needles. Mercuric chloride is soluble in water, requiring, at 0~ C., 16 parts, at 20~ C., 131 parts, at 80~ C., 4 parts of cold, and 21 parts of boiling, water for solution; it is less soluble in glycerin, 100 parts of which dissolve about 7 parts of the salt; it is freely soluble in alcohol anld ether, requiring 2~ parts of cold, and 1- part of boiling alcohol, and 3 parts of ether. The aqueous solution reddens blue litmus-paper, and has an acrid, styptic taste. In the aqueous solution of mercuric chloride, the fixed alkaline and earthy hydrates and alkaline carbonates produce, when added in small quantity, a reddish-brown precipitate; when added in excess, a yellow one; ammonium hydrate gives a white one; argentic nitrate, a curdy white one; iodides, when added in small quantity, a yellowish, and in larger quantity, a vermilion-red one, soluble in an excess of the precipitant; stannous chloride, when added in small quantity, a white, and when added in excess, a gray precipitate.- When hydrosulphuric acid is gradually added to a solution of mercuric chloride, the precipitation takes place according to the proportions of the reagent and the chloride, in progressive variation of color from white to yellow, orange, reddish brown, and black; an excess of the reagent produces at once a complete black precipitation. When the aqueous solution of mercuric chloride is rubbed upon bright copper, it coats the latter-with a brilliant metallic film. It forms white, insoluble or sparingly 15 226 MANUAL OF CHEMICAL ANALYSIS. soluble compounds with many organic substances, as albumen, fibrin, gluten, etc. Mercuric chloride is soluble, without decomposition, in nitric, hydrochloric, and sulphuric acids, and crystallizes from the solutions on cooling, if they were saturated while hot. HYDRARGYRI CHLORIDUMI ITE. HYDRARGYRI SUBCHLORIDUM. HYDRARGYRUM CHLORATUM MITE. MERCURIUS DULCIS. Calomel. Sub- or Proto-Chloride of Mercury. lercurous Chloride. Mercurous chloride varies in the minuteness of its particles, and accordingly in its appearance and in the energy of its physiological action. When obtained by sublimation, it forms ponderous, yellowish-white masses or cakes, of a fibrous, crystalline fracture, yielding a lemon-yellow streak when scratched with a knife, and having a specific gravity of 7.176. When reduced to a FIG. 6T. FIG. 68. FIG. 69.._ 250 diam. 250 diam. 250 diam. MERCUROUS CHLORIDE: By Ritration. By Cndensation. By Preipitation. fine powder by trituration and levigation, it has a dullwhite appearance with a yellowish tint; it becomes slightly yellowish when triturated with strong pressure in a porcelain mortar, and consists, when seen under the microscope, of comparatively large, transparent, crystalline fragments (Fig. 67). HYDRARGYRUM. 227 Prepared by sublimation and by condensation of the vapor by a current of air or steam, mercurous chloride (Hydrargyri Chloridum Mhite vapore paratum) forms a perfectly white and less ponderous powder, consisting of smaller laminar particles, when seen under the microscope (Fig. 68). Prepared by precipitation, mercurous chloride forms a fine, snow-white powder, consisting of minute, amorphous * particles (Fig. 69), which are not transparent. With regard to therapeutical action, mercurous chloride, obtained by sublimation and subsequent trituration and levigation, and consisting of the largest particles, has the mildest effect; next to this comes the calomel obtained by sublimation and condensation by air or steam; t that obtained by precipitation, and having the minutest division of its particles, has the most powerful physiological action. Mercurous chloride, when heated in a dry test-tube, is slowly but completely volatilized with a faint noise and without fusion. It is insoluble in the common solvents, but soluble to some extent in saliva, in the pancreatic juice, in albumen, and animal secretions. When agitated with hot water, with alcohol, or with dilute acetic, hydrochloric, or nitric acids, it is not acted upon by any of them. When boiled for some time with water, it suffers slow decomposition into metallic mercury and mercuric chloride. The alkaline hydrates and carbonates, and the hydrates of the alkaline earths, reduce mercurous chloride to black oxide. Concentrated boiling hydrochloric and sulphuric acid decompose the salt; the former producing metallic mercury and mercuric chloride, the latter mercuric sulphate and chloride. Warm concentrated nitric acid also dissolves it gradually, with the evolution of nitric-oxide vapors, forming a solution of mercuric chloride and nitrate, which solutions blacken bright copper when dropped upon it, and coat it brilliantly when rubbed upon it. Mercurous chloride is also soluble in chlorine-water without acquiring a transient or permanent yellovw color (distinction from mercurous bromide). * When obtained by precipitating a solution of mercuric chloride with sulphurous-acid gas, the resulting mercurous chloride is of a crystalline structure. ~ No other kinds of mercurous chloride can as yet be considered officinal, and no others should be dispensed for internal use, unless ordered or prescribed as "Calomel via humida paratum," or " Calomel precipitatione paratum." 228 MANUAL OF CHEMICAL ANALYSIS. Examination: When heated in a narrow test-tube, mercurous chloride must completely sublime, without previous fusion and without emitting ammoniacal odors or yellow nitrous vapors. XMercutric chloride may be detected by triturating some of the calonmel with diluted alcohol, and shaking the mixture in a test-tube, and by subsequent filtration through a moist double filter; the filtrate must impart no stain to bright copper, nor yield any reaction with hydrosulphuric acid or with argentic nitrate. Amrnmono-mercuric C(hloride.-The mercurous chloride of the preceding test, remaining upon the filter, is rinsed with diluted acetic acid through the broken filter into a test-tube, and the mixture is agitated for a few minutes and filtered. The filtrate is then tested in separate portions with hydrosulphuric acid and argentic nitrate; a black turbidity in the first instance, and a white one in the second, would indicate ammronio-mercuric chloride. IYDRARGYRI CYANIDUM. HYDRARGYRUM CYANATUM. Cyanide of Meircury. Mercuric Cyanide. Small, colorless, anhydrous, prismatic crystals, transparent when freshly prepared, but soon assuming a white and opaque appearance; when perfectly dry, they become black when exposed to heat in a dry tube, and emit vapors of mercury and a colorless inflammable gas (cyanogen), which burns, when ignited, with a purple flame; a black residue of paracyanogen, intermingled with globules of mercury, is left behind; when the salt is humid, traces of hydrocyanic acid, of carbonic acid, and of ammonia, are also formed -and evolved. Mercuric cyanide is soluble in eight parts of water and about twenty parts of alcohol; its aqueous solution evolves hydrocyanic acid upon the addition of hydrochloric acid, and gives a black precipitate with hydrosulphuric acid, but is not precipi HYDRARGYRUM. 229 tated by the alkaline hydrates and carbonates, nor by argentic nitrate, nor by albumen; stannous chloride, containing free hydrochloric acid, precipitates metallic mercury with the evolution of hydrocyanic acid. The solution of mercuric cyanide affords no mercuric stain upon bright copper. unless acidulated with hydrochloric acid. Examination: Basic oxy-mercuric cyanide is indicated by an alkaline reaction of the solution upon turmeric-paper. ilercuric chloride and other soluble mercuric salts may be detected in the solution, by the occurrence of a transient turbidity upon the gradual addition of single drops of solution of potassium iodide. HYDRARGYRI IODIDUM RUBRU]. HYDRARGYRUM BIIODATUM RUBRUM. Biniodide of Mereury. Mercuric Iodide. A heavy, crystalline powder, or small, brilliant, octahedral crystals, of a vermilion color, becoming yellow when gently heated; when heated in a dry tube (Fig. 70), mercuric iodide fuses to a yellowish-brown liquid, and sublimes into yellow rhombic scales,. which pass into the red modification of octahedral crystals, slowly on cooling, and at once by concussion. Mercuric iodide is nearly insoluble in cold, and only sparingly soluble in boiling, water; it is soluble in 130 parts of cold, and 15 parts of boiling. alcohol, less soluble in ether, and very little in glycerin and in oils. Concentrated acids, and the solutions of the alkaline hydrates, decompose it; it is freely soluble in aqueous solutions of potassium and sodium hydrates, of potassium iodide and cyanide, of mercuric chloride, and of sodium chloride and sodium hyposulphite; the latter solution deposits upon heating, if the solvent is not in excess, red mercurie sulphide. All its solutions form a black precipitate with an excess of hydrosulphuric acid, either at once, or upon the addition of an acid. 230 MAN'UAL OF CHEMICAL ANALYSIS. Mercuric iodide is partly decomposed when shaken with chlorine-water; the obtained filtrate, when rubbed upon bright FG. 70. copper, coats it with a brilliant metallic film, and, when shaken with a little chloroform, imparts to it a purple color. Examination: Jliercuric sulphide, red oxide of lead, or other fraudulent admixtures, will remain undissolved upon solution of the powder, either in solution of potassium iodide, or in 20 to 25 parts of boiling alcohol. If a residue is left, it is washed with water and subsequently treated with warm nitric acid, and filtered; the filtrate is slightly diluted, and tested with a few drops of diluted sulphuric aci(d; an ensuing white precipitate indicates lead. If a red residue remains, insoluble in nitric acid, it is tested by heating it upon platinum-foil tD redness; if it is wholly volatile, mercuric s8ulphide is recognized, and, if a residue remains, fJited admnixtures are indicated. HYDRARGYRU. 231 HYDRARGYRI XODIDUMR VIRIDE, HYDRARGYRUM IODATUM FLAVUM. Green Iodide of Mercury. Protoiodide of Mercury. Aercurous Iodide. A heavy, dirty-greenish yellow powder, which suffers grad. ual decomposition, and becomes brownish on exposure to light, heat, and air. When heated in a dry tube (Fig. 70, page 230), it becomes brownish red, fuses, and is completely volatilized, yielding a sublimate of minute yellow and scarlet crystals of mercuric iodide, intermixed with metallic mercury. Mercurous iodide is not quite insoluble in water, but insoluble in alcohol and in ether; it is decomposed by concentrated acids, by the alkaline hydrates, and also by boiling solutions of chlorides, bromides, and iodides, which convert it into mercuric iodide and metallic mercury. When mercurous iodide is agitated in a little water to which a few drops of ammonium sulphydrate have been added, and the subsequent filtrate is mixed with one drop of liquor ferri perchloridi and then agitated with a little chloroform, the latter will acquire a yellow or reddish color, which will appear still more distinct upon the subsequent addition of a little water. Examination: X.lercutic iodide may be detected- when about 10 grains of the green powder are rubbed with about 2 drachms of alcohol; the filtrate should yield no black precipitate, when added to about one ounce of hydrosulphuric acid; such a reaction would indicate biniodide. Fixed impurities will remain behind upon complete volatilization of the mercurous iodide in a dry tube; such would be very likely to originate from either the mercury or the iodine, and, if required, their nature may be determined by the methods as described on pages 238-240 and 243, 244. 232 MANUAL OF CHEMICAL ANALYSIS. IHYDRARGYRI OXIDUlt FLAVUX. HYDRARGYRUM OXYDATUM VIA HUMIDA PARATUM. Yellow Oxide of Mfercury. Precipitated Mercuric Oxide. A heavy, orange-yellow powder, without crystalline structure when seen under the microscope; it assumes a red color on being heated; it is more readily acted upon by reagents than the coairser red oxide; the latter remains unchanged when agitated with a warm solution of oxalic acid, while the yellow oxide combines with the oxalic acid, forming white mercuric oxalate; when agitated with a hot alcoholic solution of mercuric chloride, the yellow oxide becomes at once black (oxychloride), while the red oxide remains unchanged for some time. The chemical reactions of the precipitated yellow mercuric oxide, and its deportment with reagents, correspond with those of the red oxide. HYDRARGYRI OXIDUM RUBRUT. IHYDRARGYRUM OXYDATUM RUBRUM. Red Oxide of Mfercury. Mercuric Oxide. Heavy, coherent masses, consisting of bright, brick-red, crystalline scales, which, when finely pulverized, form a dull orange-red powder, of a specific gravity of 11.30; when heated in a dry tube, red mercuric oxide assumes a dark-brown appearance, but regains its original colo.r on cooling; at a heat a little above the boiling point of mercury (360~ C.), it is resolved into its constituents, and is entirely volatilized below red heat. Mercuric oxide is slightly soluble in water, so that, when agitated with boiling water, the filtrate yields a faint reaction with hydrosulphuric acid; it is insoluble in pure glycerin, in alcohol, ether, and chloroform, somewhat soluble in saliva and in albuminous animal secretions, and entirely soluble in strong and in somewhat diluted acids. The fixed alkaline and earthy hy HYDRARGYRUM. 233 drates and alkaline carbonates produce in solutions of mercuric oxide and its salts, when added in small quantity, a reddish brown, when added in excess, a yellow precipitate; ammonium hydrate, a white one; iodides (provided that the solution does not contain a large excess of acid), when added in a small quantity, a yellowish, and in a larger quantity, a vermilion-red one, soluble.in an excess of the precipitant; stannous chloride, when added in a small quantity, gives a white, and, in an excess, a gray precipitate. When hydrosulphuric acid is gradually added to the solution, a precipitate is formed which appears, according to the proportion of the reagent, successively white, yellow, orange, reddish-brown, and finally, with an excess of the precipitant, black. Examination: Xiercmric nitrate is indicated by disengagement of red nitrous vapors, when the oxide is heated in a dry test-tube. As FIG. 71. a confirmatory test, one drachm of the oxide may be agitated for a few minutes with about 2 drachms of boiling water wherein 10 grains of sodium carbonate have been dissolved; the mixture is then filtered, the filtrate nearly neutralized by a few drops of sulphuric acid, and evaporated to about half its, bulk; this is tested in two portions for nitric acid; the one by tingeing 234 MANUAL OF CHEMICAL ANALYSIS. it faintly blue with sulphuric acid solution of indigo, and subsequent gentle heating; the other by mixing it with a little concentrated solution of ferrous sulphate, and by placing the liquid carefully upon concentrated sulphuric acid (Fig. 71); a adecoloration in the first test, and the occurrence of a darkbrown color upon the line of junction between the two liquids in the second, would confirm the presence of oxyacids of nitrogen. Adrmixtures.-About 20 grains of the oxide are dissolved in about one drachm of strong nitric acid diluted with an equal volume of water; with the aid of heat, a complete solution must take place; if the oxide be very old, a slight residue of reduced mercury might remain, which, when separated and heated in a porcelain capsule, should wholly volatilize. If a red or brown residue is left from the solution, an admixture of mineral substances (brick-powder, mercuric sulphide, or red FIG. 72. oxide of lead) would be indicated. If the nature of such a residue has to be ascertained, a somewhat larger quantity may be obtained, which, when washed and dried, may be heated in a reducing-tube (Fig. 72); vermilion volatilizes, forming a fine: HYDRARGYRUM. 235 red sublimate; red oxide of lead fuses, and exhibits, when cooled, a yellow vitrified appearance, and dissolves, when boiled in concentrated nitric acid diluted with an equal bulk of water, leaving behind silicious mineral substances, if such be present. HYDRARGYRI SUBNITRAS. HYDRARGYRU M NITRICUM OXYDULATUM. Sulbnitrate of ercury. Mercurous Nitrate. Colorless, transparent rhombic or prismatic crystals,@ which, when gradually heated in a dry tube, emit yellow nitrous vapors, become yellow, then red, and are finally resolved into metallic mercury; the crystals become grayish black when moistened with lime-water. Mercurous nitrate is soluble in water with partial decomposition, and with the separation of a yellowish basic salt; it is, however, entirely soluble in water acidulated with nitric acid, forming a colorless solution, which, when rubbed on bright copper, coats it with a white, metallic film, and, when greatly diluted, yields a white precipitate with hydrochloric acid, and a black one with aqua ammonie or lime-water. Liqu6or Hydrargyri Nitrici Oxydculati of the Pharmacopcea Germanica is a solution of this salt, containing 10 per cent. of mercurous nitrate. Examination: if/ercuric nitrate may be detected by complete precipitation of the solution with diluted hydrochloric acid, and by testing the filtrate in separate portions with hydrosulphuric acid and with stannous chloride, and warming; a black precipitate with the first reagent, and a gray one with the second, would indicate mercuric nitrate. * According to the proportion between the mercury and the nitric acid employed in the preparation, there are a normal and a basic mercurous nitrate, which correspond in their chemical and therapeutical properties, except that, when rubbed with a little sodium chloride, the normal salt remains white, while the basic salt gives a grayish-green mixture. 236 MANUAL OF CHEMICAL ANALYSIS. HYDRARGYRI SULPHAS FLAVA. HYDRARGYRUM SULPHURICUM FLAVUM. TURPETHUM MINERALE. Yellow Subsulphate of Xereury. Basic Mercuric Sulphate. A heavy, lemon-yellow powder, of a crystalline structure when seen under the microscope; when heated in a dry tube, it assumes a reddish-brown hue, but regains its original color on cooling; at a higher temperature it volatilizes without fusion, yielding a white sublimate (mercuric sulphate) intermingled with gray metallic mercury; it is decomposed and entirely volatilized at a red heat, evolving vapors of mercury and of sulphurous acid. Basic mercuric sulphate is almost insoluble in cold, and sparingly soluble in hot, water, but soluble in diluted hydrochloric and nitric acids, forming colorless solutions, which, when diluted, give a white precipitate with barium salts, and which otherwise, in their deportment with reagents, resemble the solutions of mercuric chloride and oxide (pages 225 and 233). HYDRARGYRI SULPHURETUM RUBRUJ. HYDRARGYRUM SULPHURATUM RUBRUM. CINNABARIS. Cinnabar. Vermilion. Red Sul2phide of Mercury. 2iercuric Sulphide. Heavy masses, or cakes, of a specific gravity of 8.1, and of a dull blackish-red color and a brilliant crystalline texture, yielding a red streak when scratched with a knife, and a magnificent scarlet powder, which becomes black when moistened with an ammoniacal solution of argentic nitrate. When-heated in a porcelain capsule, or upon charcoal, cinnabar assumes an almost black color, but turns red again after cooling; at a strong heat, it is wholly dissipated, burning with a bluish flame, and emitting the odor of sulphurous acid; heated in a reducingtube or in close vessels, it sublimes below red heat without decomposition. IYDRARGYRUM. 237 Mlercuric sulphide is insoluble in the common solvents, nor is it acted upon by concentrated acids or by alkaline hydrates, at common temperatures; a mixture of concentrated nitric and hydrochloric acid dissolves it gradually, forming a colorless solution which, when diluted with water, gives a white precipitate with barium chloride, coats metallic copper with a film of mercury, and corresponds in its deportment with reagents to solutions of mercuric salts (pages 225 and 233). Examination: Oxides of Lead and Irorn.-About 20 grains of the cinnabar are agitated with about two fluid-drachms of. concentrated nitric acid; the scarlet color must remain unaltered, as change to a darker tint would indicate red oxide of lead; the mixture is then gently heated by immersing the test-tube in hot water, and is subsequently diluted with twice its volume of water, and filtered; the filtrate should be colorless; a yellowish appearance would indicate red basic plimbic chromate, or mercuric chromate (chromic cinnabar); it is then tested in separate portions:with hydrosulphuric acid, with sulphuric acid, and with potassimn iodide, for lead; another portion is tested with potassium ferrocyanide for ferric oxide; if this be present, the yellowish color of the nitric acid, agitated with the cinnabar, may be due only to iron. Chromates may be detected or confirmed by the occurrence of red irritating fumes of chloro-chromic acid, when about ten grains of the cinnabar are carefully mixed and heated in a testtube with a few small fragments of dry sodium chloride and a few drops of concentrated sulphuric acid. ilercuric Iodide, Realgar, and Antimonic Cinnabar.About 30 grains of the cinnabar are agitated with two fluiddrachms of warm liquor potassae; the filtrate should be colorless, should cause neither a coloration nor a turbidity when dropped into chlorine-water, and should yield a white precipitate when dropped into a dilute solution of plumbie acetate. A yellow or reddish coloration of the chlorine-water would indicate mercuric iodide, and a yellow precipitate with plumbic acetate, red arsenic sulphide (Realgar), or antimonic oxy-sulphide (Antimonic Cinnabar). If either of the latter two be indicated, the alkaline filtrate will give, upon supersaturation with hydro 238 MANUAL OF CHEMICAL ANALYSIS. chloric acid, a yellow precipitate when the first compound is present, and an orange-red one with the second. HYDRARGYRUM. Mercury. Quicksilver. A silver-white and brilliantly-lustrous metal, of a specific gravity of 13.596 at 15.5~ C.; liquid at common temperatures, and easily divisible into spherical globules; it solidifies when cooled to — 39.5 C., forming at and below that temperature a soft and malleable metal of a specific gravity of 14.4 at -40~ C.; it boils at 350~ C., forming a transparent, colorless vapor; it is, however, volatile to a perceptible extent at all temperatures above 20~ C.; when pure, it is unalterable at common temperatures, and remains bright and brilliant. Mercury is insoluble in the common solvents, in concentrated hydrochloric acid, and at common temperatures also in sulphuric acid; but it is dissolved by the latter when boiled with it, and is readily dissolved without residue by nitric acid, forming a solution, which contains mercuric nitrate when heat is applied and an excess of concentrated acid, and mercurous nitrate when the metal is in excess or is acted upon by cold and diluted nitric acid. Examination: Mercury amalgamates with many metals, and, to a certain extent, without change of its appearance and properties; the most common of such metallic impurities are lead and tin, and occasionally zinc and bismuth; their presence in the commercial metal is indicated by a dull, tarnished appearance, and a black, powdery coating of the surfaces of the metal, and of the inside of the vessels containing it, and byy'lead-gray streaks upon white paper when a few globules of the metal are allowed to roll over it. Such contamination may be ascertained by agitating for a few minutes a little of the mercury, in a strong one-ounce bottle, with a mixture of one drachm of Liquor Ferri Persulphatis (free from ferrous salt) and one drachm of water; after sub HYDRARGYRUM. 239 siding, tile aqueous liquid is poured into a test-tube, diluted with an equal volume of water, and tested with a few drops of potassium ferri cyanide; a blue turbidity will indicate the above-mentioned metallic impurities. When their nature has to be determined, the following method is practicable and simple: about one ounce of the metal, including as much of the powdery coating on the surfaces of the metal and the bottle as can be collected, is heated and volatilized in a small porcelain crucible, in a place where the vapors are readily removed by draft; if a non-volatile residue remains, it is heated to redness. A small part of the residue is then heated in a test-tube with a few drops of concentrated hydrochloric acid; the solution is decanted from the in-. soluble residue, and one drop of solution of auric chloride is added; an ensuing gray or g~fayish-purple turbidity would indicate tin. The rest of the residue in the crucible is treated with warm concentrated nitric acid; if only a partial solution takes place, FIG. T-3. and at the same time a white precipitate is formed, this may be oxide of tin or antimony; in order to distinguish them, the precipitate is separated from the acid solution, washed with a little water, and subsequently heated upon charcoal before the blow-pipe; stannolus oxide remains unchanged, while tetroxide of antimony volatilizes in white fumes, forming a white concentric incrustration on the coal (Fig. 73). The nitric-acid solution is diluted with an equal bulk of water, and part of it is tested with solution of sodium sulphate; 240 MANUAL OF CHEMICAL ANALYSIS. a white precipitate would indicate lead; another part is poured into a large beaker full of water; a white opalescence or turbidity of the water indicates bismut/h. If lead be present, the rest of the nitric-acid solution is saturated and completely precipitated with hydrosulphuric-acid gas, and allowed to stand in a corked test-tube for some hours; it is then filtered and over-saturated with aqua ammonie; a white precipitate would indicate zinc. If the precipitate is not quite white, and the lead has been completely removed, it might be due to traces of iron, of' which metal, however, mercury can only contain traces, since it does not amalgamate with it. HYDRARGYRUM AXIMONIATUM. IHYDRARGYRUM AMIDATO-BICHLORATUM. HYDRARGYRUM AMMONIATUM BICHLORATUM. HYDRARGYRUM PR2ECIPITATUM ALBUM. White Precipitate. Ammoniated'Aercury. Ammonio-mercuric Chloride. White, pulverulent, friable masses, or an opaque white powder, which, when heated, is entirely volatile without fusion'; it becomes black when moistened with hydrosulphuric acid, gray when boiled with solution of stannous chloride, and pale yellow, with the evolution of ammonia, when heated with liquor potasso. Ammonio-mercuric chloride is insoluble in the common solvents, but is gradually decomposed by boiling with water,'forming a yellow precipitate; it is readily and wholly soluble without effervescence in warm hydrochloric, nitric, and acetic acids, forming colorless solutions, which yield a white precipitate with liquor potasse and with argentic nitrate, a black one with an excess of hydrosulphuric acid, and a red one with potassium iodide, and which produce a black stain upon bright, metallic copper, coating it, when rubbed thereon, with a brilliant metallic film. Examination: X2Mercuric chloride is detected by agitating about 10 grains of the powder with about two drachms of diluted alcohol; the HYDRARGYRUM. 241 filtrate is mixed with about half an ounce of hydrosulphuric acid; a black precipitate indicates mercuric chloride. IMercurous chloride may be detected by a black coloration of the powder, when it is triturated with lime-water, or by dissolving about 10 grains of' the powder in warm diluted nitric acid; if an insoluble residue remains, it is washed by decantation, and, when the water ceases to act on blue litmus-paper, the residue is agitated with limewater; if mercurous chloride, it will become black. Plumbic Carbonate and Chloride, and Calciumn Carbonate. -Carbonates are indicated by effervescence of the powder with acids, and plumbic chloride by its insolubility in diluted nitric acid; if a residue remains, it is washed, and boiled in strong acetic acid, and the liquid tested with one or two drops of sulphuric acid for lead; which may further be confirmed by agitating the powder with warm acetic acid, and testing the filtrate in two separate portions, with sodium sulphate and with potassium iodide, drop by drop, which both form precipitates with compounds of lead, the former a white, insoluble one, the latter a yellow one, soluble in an excess of the reagent. These and all other non-volatile admixtures are also indicated by remaining behind when a few grains of the ammoniated mercury are heated and volatilized, in a narrow, dry testtube. Diammonio-mercuric chloride, or fusible white precipitate, will be indicated in this test by a partial or complete fusion of the powder, previous to its volatilization, provided that the ammonio-mercuric chloride be free from any fixed fusible admixture. Zinc and magnesium oxides may be detected, in the solution of the powder in nitric or acetic acid, by complete precipitation with hydrosulphuric acid, and by subsequent over-saturation of the filtrate with ammonium hydrate; a white precipitate will indicate either of these oxides; if the nature of the precipitate has to be determined, it is collected and washed upon a filter, and examined by the method described on page 43. Starch.-An admixture of starch is detected by the microscope, and also by a blue coloration, when about five grains of the powder are triturated, and subsequently heated to boiling,: 16 242 MANUAL OF CHEMICAL ANALYSIS. with about two drachms of water, and then tested with one drop of iodinized potassium iodide. IODOFORMUlMr. IODOFORMIUM. lodoform. Teriodide of Formyl. Methenyl Iodide. Small, lemon-yellow, friable, six-sided scales, of a pearly lustre, a peculiar, penetrating, and persistent odor, and a sweetish taste, and with a somewhat unctuous feel to the touch. Iodoform has a spec. grav. of 2.0, is volatile at common temperatures, and when heated in a dry tube, by immersing it in boiling water, sublimes at about 95~ C., solidifying in small scales; it fuses at about 1150 C., and is decomposed at 120~ C., forming violet vapors, and being resolved into iodine and hydclroiodic acid, with a residue of carbon, which burns away at a stronger heat. lodoform is almost insoluble -in water, glycerin, diluted acids, and aqueous solutions of the alkaline and earthy hydrates, but is soluble in 80 parts of cold, and 12 parts of boiling, alcohol, in 20 parts of ether, and readily in chloroform, in carbon bisulphide, and in the fixed and volatile oils. The concentrated mineral acids, when cold, have no action on iodoform; when heated, it remains unchanged with hydrochloric acid, gives a reddish-brown solution with nitric acid, remaining limpid and brown on dilution with water; it is freely dissolved, with a violet color, by hot sulphuric acid; upon dilution, however, the color disappears, and the iodoform is separated again in small yellow scales. It is not acted upon by the aqueous solutions of the alkaline hydrates, but their alcoholic solutions dissolve and decompose it, forming alkaline iodide and formiate. IODUM. 243 IODUI. IODINUM. IODINIUM. Iodine. Heavy, brilliant, crystalline plates or scales, of an opaque bluish-black appearance and imperfect metallic lustre, and of a peculiar odor, resembling faintly that of chlorine. Its specific gravity is 4.948; it melts at 107~ C., and boils at 175~ C.; it is, however, slowly volatile at common temperatures. When heated in a dry tube (Fig. 74), iodine melts and rises in deep violet vapors, which condense in the cooler parts of the tube to small, brilliant crystals. Fro. 74. Iodine is but sparingly soluble in water, requiring 5,524 parts of it at 120 C., and imparting to it a faint yellowish tinge. It is more soluble in glycerin, 100 parts of which' dissolve a little more than 1- part of iodine. It is also soluble to some extent in the aqueous solutions of certain salts, as for instance of ammonium chloride and nitrate. Aqueous solutions of hydriodic acid and of the alkaline iodides and bromides, dissolve iodine freely, as do also alcohol and ether, with a reddish-brown color, benzol and chloroform with a violet-red, and carbon bi 244 MANUAL OF CHEMICAL ANALYSIS. sulphide with a rich purple. An aqueous solution of sodium hyposulphite dissolves iodine at first without color, and afterward with a brownish-red tint. Chloroform and carbon bisulphide, when shaken with an aqueous solution of iodine, deprive it of most of the iodine, and assume, when the fluids have separated, a more or less red color, while the aqueous solution appears almost colorless. Iodine forms with starch a deep-blue compound, which offers a very delicate test for iodine in-all solutions and in bodies which contain it in the free state. Examination: Moisture is indicated in iodine by its adhering to the surface of the bottles, and by a sticky coherence of the scales. Fixed and insoluble admixtures (graphite, coal, carburet of iron, metallic oxides or sulphides) are detected by remaining behind upon the volatilization of a little of the iodine in a testtube, or upon solution of it in alcohol or in an aqueous solution of sodium hyposulphite. If the nature of such admixtures has to be determined, the residue is collected and washed upon a filter, and afterward treated with warm hydrochloric acid FIG. 75. diluted with an equal bulk of water, which dissolves metallic oxides, and to some extent the sulphides, with the evolution of hydrosulphuric acid. The obtained solution may further be examined for metals, as described in the systematic course of analysis (pages 41-43). The insoluble residue left from the LIQUORES. 245 solution in hydrochloric acid is levigated (Fig. 75), whereby graphite and carburet of iron may be separated and distinguished from heavier mineral substances. Cyanogen iodide may be detected by triturating about 30 grains of the iodine with about 2 drachms of tepid water, and by subsequent agitation of the mixture for a few minutes; it is then filtered and washed with a few drops of water, and to the filtrate is added drop by drop so much of an aqueous solution of sulphurous acid as to decolorize it; then a few drops of solution of ferrous sulphate, and subsequently of liquor potassm, are added, and the turbid liquid is then slightly oversaturated with diluted hydrochloric acid; if a blue precipitate takes place now, either at once or gradually, and, upon warming, cyanogen iodide is indicated. The volumetric estimation of iodine has already been described on page 64. LIQUOR AXMONII ACETATIS. LIQUOR AMMONII ACETICI. Solution of Ammonium Acetate. A clear, colorless liquid, without empyreumatic odor, and of a mild, saline taste; it contains about six per cent. of neutral ammonium acetate, and has a spec. grav. of from 1.012 to 1.015 (1.028-1.032, Pharm. German.); it is wholly volatile upon evaporation, and emits the odor of ammonia when heated with potassium hydrate, and that of acetic acid when heated with sulphuric acid; it assumes a red color upon the addition of a trace of ferric chloride. Examination: lJetallic impurities may be detected by mixing the solution with an equal bulk of hydrosulphuric acid, and then over-saturating it, first with acetic acid, and subsequently with aqua amnmonive. Sulphates and chlorides may be detected by a white turbidity, when the liquid is acidulated with acetic acid and tested, in separate portions, with barium nitrate for the former salts, and with argentic nitrate for the latter. 246 MANUAL OF CHEMICAL ANALYSIS. LIQUOR ANTIMONII CHLORIDI. LIQUOR STIBII CHLORATI. BUTYRUM ANTIMONII CHLORIDI, Solution of Trichloride of Antimony or of Antimonious Chloride. A dense, transparent, colorless or pale-yellow liquid, of 1.470 spec. grav. (1.36, Pharmacopcea Germanica). Dropped into water, it gives a white, bulky precipitate (antimonious chloride with antimonious oxide-Al-garoth's Powder), which is redissolved upon addition of potassium hydrate or tartaric acid. The solution with potassium hydrate remains unchanged, or gives only a slight turbidity, with hydrosu]phuric acid, and yields a black precipitate with argentic nitrate, while the solution with tartaric acid gives a copious orange-red precipitate with hydrosulphuric acid, and a white one with argentic nitrate. Examination: About 40 drops of the liquor antimonii chloridi are added to a solution of half a drachm of tartaric acid in half an ounce of water; this solution may serve for the following tests: Antimnonic chloride is detected by a yellow coloration of the solution upon the addition of a few drops of potassium iodide. -lead and capper are detected in the solution, the former by a white precipitate with dilute solution of sodium sulphate, the latter by a bluish coloration with aqua ammonite in excess. Arsenic may be detected by heating, in a test-tube, about two drachms of a mixture consisting of equal volumes of the liquor antirnonii chloridi and concentrated hydrochloric acid, with a strip of tin-foil (real tin) or with about 20 drops of concentrated solution of stannous chloride; a brown precipitate would indicate arsenic, which may further be identified by collecting the precipitate by decantation, and by subsequent washing with a little solution of tartaric acid; it is then dried, and may be examined by heating part of it with exsiccated sodium carbonate, upon charcoal, before the blow-pipe (Fig. 73, p. 239), as well as by heating another portion of it, with a little potassium cyanide, in a reduction-tube (Fig. 63, p. 213); arsenic will be recognized by its smell in the first test, and by a metallic mirror in the second. LIQUORES. 247 LIQUOR CALCIS. AQUA CALCIS. AQUA CALCARITE. Lime- Water. Solution of Calcium Hydrate. A saturated solution of calcium hydrate, containing nearly one grain of the hydrate, or nearly three-quarters of a grain of calcium oxide, in each ounce of water. Lime-water has an alkaline reaction upon test-paper, and absorbs carbonic acid from the air, forming on its surface a pellicle consisting of minute plates of calcium hydrocarbonate; its alkaline reaction disappears when an excess of carbonic-acid gas has been passed through it, and the excess has been expelled afterward by boiling. Lime-water affords no precipitate with sulphuric acid (distinction from solutions of barium or strontiumn hydrate), but it forms white precipitates with carbonic, boracic, phosphoric, arsenious and arsenic, oxalic, and tartaric acids and their salts, and precipitates the solutions of those salts whose metallic oxides or hydrates are insoluble in water. The quality of lime-water is best ascertained by its property, when warmed in a test-tube, of separating nearly half the quantity of calcium hydrate in minute hexagonal prisms; upon cooling, the crystals redissolve, and the water becomes perfectly clear again. LIQUOR FERRI ACETATIS. LIQUOR FERRI ACETICI.* Solution of Ferric Acetate. A transparent, dark, reddish-brown liquid, of from 1.134 to 1.138 spec. gravy.; it has a faint odor of acetic acid, which api Liquor Ferri acetici, of the Pharmacopcea Germanica, is prepared by complete precipitation of 10 parts of solution of ferric sulphate, of 1.31 spec. grav., with eight parts of aqua ammoniae, of 0.960 spec. grav., both greatly diluted with water; the precipitate is collected, and washed upon a flannel or felt filter, and, when the water has dropped off, is subjected to a gentle pressure; the soft, humid mass of ferric hydrate is then transferred into a flask, and dissolved in six parts of diluted acetic acid, of 1.040 spec. gray. 248 MANUAL OF. CHEMICAL ANALYSIS. pears, however, strongly upon warming; this may also be recognized by the formation of white vapors, when a glass rod, moistened with aqua ammoniae, is brought near the liquid; it produces a deep-blue precipitate, when a few drops are allowed to fall into a mixture of several ounces of water with a few drops of hydrochloric acid and of solution of potassium ferrocyanide. Examination: About one fluid-drachm of the liquid is diluted with two drachms of water, and completely precipitated with aqua ammonie; the filtrate must be wholly volatile when a few drops of it are evaporated in a porcelain cqpsule; a viscid residue, which becomes charred, at a stronger heat, with the evolution of vapors having the odor of caramel, would indicate sugar or fruit-acids, which, when present in considerable quantities, prevent the complete precipitation of the ferric solution by ammonium hydrate. A bluish tint of the filtrate would indicate copper, which, with other metallic impurities, may further be ascertained by mixing it with hydrosulphuric acid, and subsequently over-saturating with acetic acid. LIQUOR FERRI NITRATIS. LIQUOR FERRI NITRICI. LIQUOR FERRI PERNITRATIS. ~Solution of Pernitrate of Iron. Solution of Ferric Nitrate. A pale-yellow liquid, of a spec. grav. between 1.060 and 1.070, and of a chalybeate, astringent, acid taste. Added to water, it gives a deep-blue precipitate with potassium ferrocyanide, but none with potassium ferricyanide,-and yields a reddish-brown precipitate with aqua ammonie; when a few drops of a concentrated solution of ferrous sulphate are added to a little of the solution of ferric nitrate, and the mixture is carefully transferred upon concentrated sulphuric acid (Fig. 71, p. 233), a dark zone, indicating nitric acid, will ensue upon the line of contact between the two liquids. LIQUORES. 249 One fluidounce of the liquid, completely precipitated by aqua ammonie, yields a reddish-brown precipitate of ferric hydrate, which, when washed, dried, and ignited, weighs between 8 and 10 grains. Examination: Metals.-In the ammoniated filtrate of the'preceding quantitative test, or in the liquor ferri nitrici, when completely precipitated at common temperature, by aqua ammonioe, and filtered, copper will be indicated by a blue color of the liquid, and zinc by a white turbidity upon the addition of a few drops of ammonium sulphide. Chloride and sulphate may be detected, in'the diluted solution, by white precipitates when tested with argentic and with barium nitrates. LIQUOR FERRI SULPHATIS. LIQUOR FERRI SULPHURICI OXYDATI. Solution of Ferric Sulphate. The U. S. Pharmacopoeia has two solutions of ferric sulphate, Liquor Ferri subsulphatis, having a spec. grav. of 1.552, and iiquor Ferri tersulphatis, having a spec. grav. of 1.320. Both are solutions of ferric sulphate, the former one being less acid, and containing some basic ferric sulphate, and usually some nitrate. The -Liguor Ferri pers6ulphatis of the British Pharmacopceia has the spec. grav. of 1.441, and that of the Pharmacopcea Germanica a spec. grav. of 1.319. They all are transparent, red or reddish-brown liquids, without odor, of an astringent, metallic taste, and miscible in all proportions, with water, alcohol, and glycerin. A few drops of either of them, added to water, form a mixture in which potassium ferricyanide produces no reaction, but ferrocyanide gives a dark-blue precipitate, aqua ammonie a bulky, reddishbrown one, and barium chloride a white one. Examination: Copper and Zinc.-About two drachms of the liquor ferri are diluted with about two ounces of water, and completely 250 MANUAL OF CHEMICAL ANALYSIS. precipitated with aqua ammonihe; the whole is heated, and subsequently filtered; the filtrate will appear bluish, if copper be present, and should be entirely volatile upon platinum-foil; a fixed residue would indicate alkaline, earthy, or motallic inmp9urities. Part of the filtrate is mixed with an equal volume of hydrosulphuric acid; an ensuing wvhite precipitate would indicate zinc, and a dark one, insoluble upon over-saturation with hydrochloric acid, copper. Nitric acid and nitrates nmay be detected in a portion of the filtrate of the preceding test, by over-saturating it with concentrated sulphuric acid, and by subsequently adding one drop of a solution of potassium permanganate, or indigo solution, and gently warming. A decoloration will indicate nitric acid and nitrates. LIIQUOR HYDRARGYRI NITRATIS. LIQUOR HYDRARGYRI NITRICI OXYDATI. Solution of Pernitrate of Mercury. Solution of ilercuric Nitrate. A dense, transparent, nearly colorless, acid liquid, of a spec. grav. of 2.165, when prepared according to the U. S. Pharmacopoeia, and of 2.246, when prepared according to the British Pharmacopoeia. When a few drops of it are evaporated at a gentle heat, upon platinum-foil, they leave a white residue, which, upon increased heat, becomes successively yellow, red, brown, and is finally wholly dissipated. The solution remains limpid on the addition of water or of diluted hydrochloric acid (evidence of the absence of subnitrate); it gives a dull yellow precipitate with an excess of the fixed alkaline and earthy hydrates, a white one with ammonium hydrate, and a black one with an excess of hydrosulphuric-acid; it deposits a brilliant metallic coating on bright copper, and shares, in its deportment with reagents, the general characteristics of mercuric salts, as described under mercuric chloride and oxide (pages 225 and 233). It causes a crystal of ferrous sulphate, dropped into it, as well as the liquid around the salt, to assume a deep-brown color. LIQUORES. 251 When diluted with about ten times its bulk of water, it should not give a turbidity when tested, in separate portions, with a few drops of solutions of argentic and of barium nitrates. LIQUOR PLUMBI SUBACETATIS. LIQUOR PLUMBI SUBACETICI. ACETUM PLUMBICUM. Solution of Subacetate of Lead. Solution of Triplumbic Acetate. A dense, clear, colorless liquid, of 1.267 spec. grav. (1.2351.240 Pharmacopcea Germanica), having an alkaline reaction and a sweet, astringent taste, and becoming turbid by absorption of atmospheric carbonic acid, and by dilution with water containing carbonates, sulphates, or carbonic acid. It is precipitated, whether diluted with water or not, by the alkaline and alkaline-earthy hydrates and carbonates, by sulphuric, hydrochloric, oxalic, tannic, and other acids and their salts, and bv almost all neutral salts; it forms white, opaque, insoluble compounds with vegetable gums, mucilages, and extracts, and with vegetable and albuminous substances. Liquor plumbi subacetatis gives a yellow precipitate with potassium iodide, and a black one with hydrosulphuric acid; it forms an opaque, white jelly when mixed with mucilage of gum; it may be recognized as containing an acetate, by evolving the odor of acetic acid, when heated with a few drops of sulphuric acid. Traces of copper are indicated by a faint greenish color of the liquid, and may be further recognized by a bluish coloration of the filtrate, when a little of the liquor plumbi subacetatis is mixed with an excess of aqua ammoni 252 MANUAL OF CHEMICAL ANALYSIS. LIQUOR POTASSME. LIQUOR POTASSII HYDRICI. LIQUOR KALI CAUSTICI. Solution of Potassa. Solution of Potassium Hydrate. A colorless, limpid liquid, without odor, and of an acrid, caustic taste and a soapy feel when rubbed between the fingers; it has a destructive action on vegetable and animal substances, and is a powerful solvent for many organic and mineral compounds; it abs6rbs carbonic acid from the air; its spec. grav. is 1.065, and it contains 5.80 per cent. of potassium hydrate.* Examination: Carbonate is indicated by effervescence or by the formation of gas-bubbles, when an equal volume of acetic acid is added to the liquor potassue, or it may also be detected by the formation of a white precipitate when a little of the liquor potassm is mixed with an equal bulk of water, and is then added to limewater. Potassium chloride, sulphide, and hyposulphite, may be detected by dropping a little of the liquor potassae into diluted solution of argentic nitrate; a grayish-brown precipitate will take place, completely soluble upon addition of nitric acid in excess; if the precipitate does not wholly dissolve, and leaves behind a white residue, chloride is indicated; when the residue is black, sullphide or hyposulphite. Sulphate, Silicate, and Alumi2,na.-A little of the liquor potassme is slightly over-saturated with diluted nitric acid; part of the solution is tested with barium nitrate for sulphate; another part may also be tested with argentic nitrate for chloride; the rest of the solution is evaporated, in a porcelain capsule, to dryness; the remaining salt must yield a limpid solution with water; a white turbidity would indicate silicate; the solution, when necessary, is filtered, and-then tested with a few drops of ammoniurn chloride and aqua ammoniae for alumina, which, when present, will cause a white precipitate. Calcium salts may be detected, in the diluted liquor potas* Liquor Kali caustici, of the Pharmacopoea Germanica, has a spec. grav. of from 1.330 to 1.334, and contains 33.3 per cent. of potassium hydrate, or from 28 to 29 per cent. of potassium oxide. LIQUORES. 253 se, by a white precipitate with ammonium oxalate, or with sodium carbonate..Metallic impurities are indicated by a dark coloration or turbidity when the liquor potassie is mixed with twice its volume of hydrosulphuric acid, and subsequently over-saturated with acetic acid. For TVolumetric Estimation, see page 58. T A BLE OF THE QUANTITY BY WEIGHT OF POTASSIUM OXIDE CONTAINED IN 100 PARTS BY WEIGHT OF SOLUTION (LIQUOR POTASS1E) AT DIFFERENT DENSITIES. Temperature, 17.50 0. Specific Specific Specific Specific Gravity. Gravity. _ Gravity. Gravity. ~ 1.576 45 1.414 34 1.269 23 1.135 12 1.568 44.5 1.407 33.5 1.263 22.5 1.129 11.5 1.560 44 1.400 33 1.257 22 1.123 11 1.553 43.5 1.393 32.5 1.250 21.5 1.117 10.5 1.545 43 I1.386 32 1.244 21 1.111 10 1.537 42.5 1.379 31.5 1.238 20.5 1.105 9.5 1.530 42 1.372 31 1.231 20 1.099 9 1.522 41.5 1.365 30.5 1.225 19.5 1.094 8.5 1.514 41 1.358 30 1.219 19 1.088 8 1.507 40.5 1.352 29.5 1.213 18.5 1.082 7.5 1.500 40 1.345 29 1.207 18 1.076 7 1.492 39.5 1.339 28.5 1.201 17.5 1.070 6.5 1.484 39 1.332 28 1.195 17 1.065 6 1.477 38.5 1.326 27.5 1.189 16.5 1.059 5.5 1.470 38 1.320 27 1.183 16 1.054 5 1.463 37.5 1.313 26.5 1.177 15.5 1.048 4.5 1.456 37 1.307 26 1.171 15 1.042 4 1.449 36.5 1.301 25.5 1.165 14.5 1.037 3.5 1.442 36 1.294 25 1.159 14 1.031 3 1.435 35.5 1.288 24.5 1.153 13.5 1.026 2.5 1.428 35 1.282 24 1.147 13 1.021 2 1.421 34.5 1.275 23.5 1.141 12.5 1.015 1.5 With the decrease and increase of temperature, the density of the solution suffers a corresponding increase or decrease, alnounting, for each degree of the centigrade thermometer, in either directionFor solution of a specific gravity of 1.576 to that of 1.500, to about 0.00055. " " " " 1.484'" 1.358 " 0.0005. " " " " 1.345 " 1.281 " 0.0004.,",,. 1.'219 " 1.111 " 0.00033. 254 MANUAL OF. CHEMICAL ANALYSIS. LIQUOR POTASSII ARSENITIS. LIQUOR POTASSII ARSENICOSI. LIQUOR KALI ARSENICOSI. Solution of Potassium Arsenite. Fowler's Solution. The solution of potassium arsenite -has a slight alkaline reaction; it gives, with nitrate of silver, a bright-yellow precipitate, soluble in aqua ammonioe; this solution, when gently warmed for some time, by immersing the test-tube in hot water, suffers a reduction of the silver salt, and deposits the metal, as a brilliant coating, upon the walls of the test-tube. Hydrosulphuric acid produces no immediate precipitate in the solution of potassium arsenite, but, upon the addition of hydrochloric acid, there at once appears a lemon-yellow precipitate, soluble in ammonium hydrate or carbonate. A quantitative estimation of the arsenious acid contained in liquor potassii arsenitis may be made, by completely precipitating, with hydrosulphuric acid, 10 drachins of the solution, diluted with an equal volume of water, and acidulated with hydrochloric acid; the precipitate is collected and washed upon a tared filter, and, when completely dried, is weighed. The weight of the arsenious sulphide, divided by 1.242, gives the quantity of arsenious acid contained in 10 drachms of the solution, which should be five grains. The quantitative estimation may also be made by the volumetric test: 68.30 grammes of the solution of potassium arsenite, neutralized with about 25 grains of sodium bicarbonate, and diluted with an equal bulk of water to which a little mucilage of starch has been added, will require 100 cubic centimetres of the test-solution of iodine (page 63). LIQUOR SODSE. LIQUOR SODII HYDRICI. LIQUOR NATRI CAUSTICI. Solution of Soda. Solution of Sodium Hydrate. A colorless, limpid liquid, of an acrid, caustic taste, a soapy feel, and a strong alkaline reaction; it has a destructive and LIQUORES. 255 solvent action on vegetable and animal matters, absorbs carbonic acid from the atmosphere, has a spec. grav. of 1.07i, and contains 5.7 per cent. of sodium hydrate.* Examination: Sodium carbonate is indicated by effervescence, or by the formation of gas-bubbles, when the liquid is mixed with concentrated hydrochloric acid; it may also be detected by the formation of a white precipitate upon mixing a little of the liquid with twice its volume of lime-water. Sodium sulphate and chloride are indicated by white precipitates, when the diluted liquid is slightly over-saturated with diluted nitric acid, and tested with barium nitrate for sulphate, and with argentic nitrate for chloride. Calcium sal9ts may be detected by a white precipitate, when the diluted liquid is tested with solution of sodium carbonate. Potassium hydrate may be recognized by a white, granular precipitate, on dropping the liquid into' a strong solution of tartaric acid, allowing the latter to remain in excess. TA B.. E OF THE QUANTITY BY WEIGHT' OF SODIUM OXIDE CONTAINED IN 100 PARTS BY WEIGHT OF SOLUTION (LIQUOR SODAE) AT DIFFERENT DENSITIES. TEMPERATURE 1[.5~ C. Specific ~c Specific Specific Specific (Gravity. Gr lavity. Gravity. Gravity. 1.500 35 1.389 27.5 1.281 20 1.174 12.5 1.492 34.5 1.382 27 1.274 19.5 1.167 12 1.485 34 1.375 26.5 1.266 19 1.160 11.5 1.477 33.5 1.367 26 1.259 18.5 1.153 11 1.470 33 1.360 25.5 1.252 18 1.146 10.5 1.463 32.5 1.353 25 1.245 17.5 1.139 10 1.455 32 1.345 24.5 1.238 17 1.132 9.5 1.448 31.5 1.338 24 1.231 16.5 1.125 9 1.440.1 1.331 23.5 1.224 16 1.118 8.5 1.433 30.5 1.324 23 1.217 15.5 1.111 8 1.426 30 1.317 22.5 1.210 15 1.104 7.5 1.418 29.5 1.309 22 1.203 14.5 1.097 7 1.411 29 1.302 21.5 1.195 14 1.090 6.5 1.404 28.5 1.295 21 1.188 13.5 1.083 6 1.396 28 1.288 20.5 1.181 13 1.076 5.5 * Liquor Natri caustici of the Pharmacopca Germanica has a spec. grav. of from 1.330 to 1.334, and contains from 30 to 31 per cent. of sodium hydrate, or about 23.5 per cent. of sodium oxide. 256 MANUAL OF CHEMICAL ANALYSIS. With the decrease and increase of temperature, the density of the solution suffers a corresponding increase or decrease, amounting, for each degree of the centigrade thermometer, in either directionFor solution of a specific gravity of 1.500 to that of 1.853, to about 0.00045. "4 "i "4 "6 1.345 " 1.210 " 0.0004. "6 fi " 1.203 " 1.076 " 0.00033. LITHEI CARBONAS. LITHIUM CARBONICUM. Carbonate of Lithium. Lithium Carbonate. An odorless, white, granular powder, fusible at a high temperature; when heated in an alcohol-flame, upon the looped end of platinum wire, previously moistened with hydrochloric acid, it imparts a crimson color to the flame. Lithium carbonate is but sparingly soluble in water or alcohol, requiring about 108 parts of the former, at 16~ C.,for solution; it is readily dissolved, with effervescence, by diluted acids; its solution in diluted hydrochloric acid, when evaporated to dryness, leaves a residue which is readily and completely soluble in a few drops of a mixture of equal parts of alcohol and ether (distinction from potassium and sodium chlorides). When this latter solution is poured into a small porcelain capsule, and ignited, it burns with a red flame; the residue left in the capsule after the ignition is then dissolved in a few drops of water, and added to a very dilute solution of sodium phosphate, to which one drop of solution of ammonium chloride has been added; a white, crystalline precipitate of lithium phosphate, readily soluble in hydrochloric acid, will appear. Examination: One'grain of the lithium carbonate is placed in a small testtube, and two drachms of cold water, exactly weighed, are gradually added to the carbonate, with frequent agitation, closely observing the point when complete solution of the salt takes place; it must not occur until nearly the whole of the water is added; otherwise an admixture of alkaline or other salts is LITHIUM. 257 indicated; in this case, the presence of the former may be ascertained by the above-described method, depending upon the solubility of lithium chloride in a mixture of alcohol and ether. Calciqtum salts may be detected in the aqueous solution of the lithium carbonate, previously neutralized with hydrochloric acid, by a white turbidity with ammonium oxalate. lliagnesium and aluminzum, may be detected in the solnition, neutralized with hydrochloric acid, by testing it, in two separate portions, with lime-water and with sodium carbonate; a white turbidity would indicate the presence of compounds of either of these elements. iJetallic impurities are detected, in the aqueous solution, by hydrosulphuric acid, and subsequent acidulation with hydrochloric acid. LITHII CITRAS. LITHIUM CITRICUM. Citrate of Lithium. Lithium Citrate. A white, amorphous, deliquescent powder, soluble in 25 parts of water, and also soluble in alcohol. Heated in a porcelain capsule, it blackens, evolves inflammable vapors, and leaves a white residue, which, when dissolved in a little alcohol, with one or two drops of hydrochloric acid, and ignited, imparts a crimson color to the flame. When the aqueous solution of lithium citrate is completely precipitated with calcium chloride, the filtrate, when heated, will become turbid, and when filtered after cooling, and the filtrate reheated to boiling, it becomes turbid again (evidence of the presence of citric acid). Ten grains of lithium citrfate, heated for about 15 minutes, in a tared porcelain crucible, at a low red heat, with free access of air, leave 5.3 grains of a white residue of lithium carbonate. Examination: Potassium salts are detected in the concentrated solution of the citrate, by a white, crystalline precipitate, upon the ad17 25 8 MANUAL OF CHEMICAL ANALYSIS. dition of a few drops of concentrated solution of sodium bitartrate. Sodizur salts are detected in the solution, by a white precipitate when tested with potassium antimoniate. The presence of potassium and soditmn salts may also he ascertained by dissolving, in one or two drops of diluted hydrochloric acid, the residue of lithium carbonate obtained by incineration of the citrate; this solution is evaporated to dryness, and is subsequently dissolved in a few drops of a mixture of equal parts of alcohol and ether; a complete solution should take place, as an insoluble residue would indicate potassium or sodium chlorides. Idetallic impurities may be detected, in the solution, by hbyvdrosulphuric acid. MAGNESIA. MAGNESIA USTA. MAGNESII OXIDUM. MAGNESIUM OXYDATUM. Mfagnesia. Ccalcined Magnesia. 3lagnesium Oxide. A white, inodorous, bulky, more or less light powder, of a slightly alkaline taste, and an alkaline reaction upon moist blue litmus-paper; when exposed to heat, it suffers no change whatever. Magnesia is almost insoluble in water, but unites readily with one equivalent of water, at once when mixed with it, or slowly on exposure to the atmosphere, forming a hydrate which is soluble in about 5,000 parts of cold, and 36,000 parts of boiling, water, and which attracts carbonic acid from the air. When triturated with water, magnesia must dissolve without effervescence, upon the addition of sulphuric acid (evidence of the absence of carbonate), and must form a clear solution (evidence of the absence of calcium, barium, and strontium oxides); this solution may be divided into two portions, one of which is mixed with an equal volume of hydrosulphuric acid, and is subsequently slightly over-saturated with aqua ammonia; a dark coloration or turbidity, either before or after the addition of the ammonium hydrate, would indicate metallic MAGNESIUM. 259 impurities, and a white precipitate, on the addition of the aqua ammoni a, zinc oxide; the filtrate is tested with ammonium oxalate for calciut6m. The second portion of the solution in sulphuric acid is over-saturated with aqua ammoniae, and tested with sodium phosphate, which will produce a copious, white, crystalline precipitate of ammonio-magnesium phosphate. Magnesia is liable to contain the impurities of the magnesium carbonate from which it has been obtained, and may be examined for them, if they have not been ascertained by the preceding tests for identity and purity, by the methods described on page 260. IAGNESII CARBONAS. MAGNESIA CARBONICA. MAGNESIA ALBA. Carbonate of Magnesium. Magnesium Carbonate. White, bulky, pulverulent masses, commonly in square cakes, or a light, white powder, smooth to the touch, and nearIv insoluble in water, but soluble with effervescence in dilute acids, yielding limpid, colorless solutions; these, after the addition of' a little solution of ammonium chloride, are not precipitated upon slight over-saturation with ammonium hydrate, and render a copious white precipitate of ammonio-magnesium phosphate, upon the addition of sodium phosphate. Magnesium carbonate is decomposed at a red heat, and also by all acids, and by the fixed alkaline hydrates. One drachm of magnesium carbonate requires for saturation 7.93 grains of citric, and 94.23 grains of tartaric, acid; 100 parts of it, when calcined at a red heat, leave 40 to 43 parts of magnesium oxide. Examination: About 20 grains of the powdered magnesium carbonate are mixed and agitated with about one ounce of warm water; the filtrate is tested with turmeric-paper, and, if this becomes brown, alkaline carbonates are indicated; when a few drops of the filtrate are evaporated upon platinum-foil, only a very 260 MANUAL OF CHEMICAL ANALYSIS. slight residue should remain. The magnesium carbonate left on the filter is rinsed into a flask, by means of a washing-bottle; the mixture is warmed, and sulphuric acid added, drop by drop, until solution is effected; a remaining slight turbidity would indicate traces of silicic acid. The solution is filtered, if necessary, and saturated with hydrosulphuric-acid gas, and is then rendered alkaline by the addition of a strong solution of ammonium carbonate; an ensuing greenish turbidity would indicate salts of iron; a light reddish one, salts of manganese; a white one, not disappearing upon the addition of aqua ammoniae, salts of aluminiuwm or zinc (the incidental presence of phosphates would also give a white precipitate). In order to distinguish them, tile precipitate is washed, and subsequently dissolved in a few drops of liquor potassm, and the solution diluted, and tested with ammonium chloride, which precipitates aluminium hydrate, while zinc remains in solution, and may be recognized by reprecipitation with hydrosulphuric acid. The ammoniacal filtrate is then tested with a few drops of ammonium oxalate; a white precipitate, insoluble upon the addition of ammonium chloride, would indicate salts of calciubm. Chlorides and sulphates may be detected, in the diluted solution of the magnesium carbonate in diluted sulphuric acid, by testing the same in separate portions, with barium nitrate for sulphates, and with argentic nitrate for chloride. MAGNESII SULPHAS. MAGNESIA SULPHURICA. Epsom Salt. Sulphate of iagnesium. Magnesium Sulphate. Colorless, transparent, rhombic prisms, but usually met with in commerce as small, acicular needles; they contain seven molecules (51.22 per cent.) of water of crystallization, six of which pass off at 120~ C.; the last molecule is not expelled below 220~ C.; the crystals do not effloresce at common tem MAGNESIUM. 261 peratures and in ordinary atmospheric humidity, but they do so slowly in warm, dry air. When heated, they undergo aqueous fusion, give out their water of crystallization, and at a red heat undergo igneous fusion, with partial decomposition. Magnesium sulphate dissolves in three parts of cold, and in one part of boiling, water, but is insoluble in alcohol; its aqueous solution has a nauseous, bitter taste, and a neutral reaction on test-paper; it is decomposed, and gives white precipitates, with the fixed alkaline hydrates and carbonates, and also with the earthy hydrates and their soluble salts; ammonium hydrate and carbonate do not at once cause a precipitate in dilute solutions of magnesium sulphate, or, if so, only an incomplete one, since ammonium salts, when present or formed in aciduIous solutions, hinder or retain this reaction; but, on addition of phosphoric acid or solutions of tri-basic phosphates, a complete precipitation takes place, which precipitate, however, is soluble in dilute acids. The crystals of magnesium sulphate are isomorphous with those of zinc sulphate, and cannot be distinguished from them by the eye; it is easy, however, to discriminate between them, not only by the difference in taste, but also by the action of a few drops of ammonium sulphydrate on their aqueous solutions; that of magnesium sulphate, in this case, remains unchanged, while solution of zinc sulphate yields a white precipitate. Examination: 3Metals may be detected by the occurrence of a turbidity, when the concentrated solution of magnesium sulphate is mixed with twice its bulk of hydrosulphuric acid, and when subsequently a few drops of ammonium sulphydrate are added; a white precipitate with the latter reagent would indicate zinc; when a dark precipitate is formed, copper and iron are indicated, and may be confirmed in the slightly-acidulated solution of the salt, the former by a reddish-brown precipitate, the latter by a blue one, with potassium ferrocyanide. Alkaline sntlphJates may be detected by boiling, in a porcelain capsule, to about half its original bulk, a solution of about 20 grains of the magnesium sulphate in three ounces of water, with one drachm of barium carbonate; ammonium sulphate will be recognized during the ebullition by the odor of ammo 262 MANUAL OF CHEMICAL ANALYSIS. nia, and by white fumes when a glass rod, moistened with acetic acid, is held over the hot liquid; sodium sulphate will be indicated by the alkaline reaction of the filtrate with litmus and turmeric papers. UCalcium salts may be detected, in the diluted solution of the salt, by a white turbidity with ammonium oxalate. One hundred grains of magnesium sulphate, dissolved in boiling water, and completely precipitated by a boiling solution of sodium carbonate, yield a precipitate which, when washed and dried, weighs 34 grains, and when calcined at a red heat, 16.26 grains. A guantitative estimation of magnesium suzlplate may be afforded, by making a solution of 100 grains of the salt in water to which subsequently have been added a little solution of ammonium chloride and some aqua ammoniae, and completely precipitating it with sodium phosphate; the mixture is allowed to stand for 10 or 12 hours, when the precipitate is collected upon a filter, washed with very dilute aqua almmoniae, and, when dry, completely incinerated in a porcelain crucible. The weight of the residue, divided by 2.775, shows the percentage of magnesium oxide; and when the number thus obtained is multiplied by 2.216, the product represents the percentage of crystallized magnesium sulphate in the salt under examination. MANG.ANESII OXIDUM NIGRUX. MANGANUM HYPEROXYDATUM. MANGANESIUM OXYDATUM NATIVUM. Black Oxide of Manganese. Pyrolusite. kfanganese Dioxide. Heavy, compact masses, of a dull-black or brownish-black, earthy appearance, or masses of acicular or rhombic crystals of a black, metallic lustre, and, if pure pyrolusite, of a spec. gravy. of 4.9. In commerce, it occurs usually ground, as a coarse, dull, black powder, consisting of manganese dioxide, sesqui-oxide, and monoxide, and is contaminated with the gangue (quartz, felspar, barytes, limestone, etc.), which frequently amount to 40 or 50 per cent. MANGANESIUM. 263 Manganese dioxide is infusible and unalterable by heat, except that it loses oxygen; it does not combine with acids, but is decomposed by. them; it is insoluble in water. When a particle of it is heated to redness upon platinum-foil, with a few grains of potassium hydrate and nitrate or chlorate, it yields a dark-green fuse, which dissolves in water, with a green color, changing to purple when the solution is boiled. When heated in a test-tube, with hydrochloric. acid, chlorine-gas is evolved, and a brown solution obtained, which, when filtered, and saturated with aqua ammonite, gives a flesh-colored precipitate with hydrosulphuric acid; the color of this precipitate is, however, frequently rendered darker, or even brownish black, by the presence of oxides of iron and other metals. Since the value of pyrolusite, for its application in the arts and trades, depends less upon the nature of its impurities than upon the percentage of real manganese dioxide, an examination of the mineral is invariably required before its application, and is mainly directed to the determination of the amount of dioxide. Among the several methods of conducting the assay, the two following are simple and accurate, the one being an approximate, the other a quantitative one: 1. Ten grains of the finely-powdered black manganese dioxide are added, in a small flask, to a solution of 40 grains of granular ferrous sulphate in two drachms of water, and, when mixed by gentle agitation, one fluid-drachm of concentrated hydrochloric acid is added, and the mixture allowed to stand in a warm place, with occasional gentle agitation, for several hours; a few drops of diluted hydrochloric acid are then added, and the mixture heated to boiling, and, after a while, filtered; the filtrate is diluted, and tested with potassium ferricyanide; if it gives no blue precipitate, the test bears evidence that the pyrolusite contains at least 60 per cent. of real manganese dioxide; if a blue precipitate takes place, the peroxide is wanting in that strength in proportion to the amount of the precipitate. 2. Fifty grains of the black oxide of manganese, in a fine powder, are carefully introduced into the flask A (Fig. 76) of the little apparatus described on page 60, into which previously have been poured 100 grains of concentrated hydrochloric acid 264 MANUAL OF CHEMICAL ANALYSIS. and about half an ounce of water; 50 grains of pure, crystallized oxalic acid are then added, the cork carrying the tubes is fitted, and the whole apparatus quickly weighed or counterpoised; ___________ | the flask B is charged with a little concentrated sulphuric acid, through which the evolved carbonic-acid gas has to pass, and A which absorbs and retains the moisture; gentle heat is applied n~~a~~-~-~ ii Bto the flask A, as long as a brisk evolution of gas takes place; the process is completed when this acFIG.76. tion and the passage of gas-bubbles through the sulphuric acid both cease, and the black color of the mixture has changed to a more or less brown one;* the residual gas is then driven off, by momentary ebullition, and the apparatus weighed. Every two molecules of carbonic acid evolved correspond to one molecule of manganese dioxide decomposed; the molecular weight of the latter (87) being so nearly equal to twice that of carbonic acid (44), that the loss of weight suffered by the apparatus may be taken to represent the quantity of real manganese dioxide in 50 grains of the sample; and it has only to be doubled in order to express the percentage. MANGANESII SULPHAS. MANGANUM SULPHURICUM. Sulphate of Manganese. Manganous Sulphate. Colorless or pale rose-colored prismatic crystals, occurring in three different forms, with different quantities of water of crystallization: (1.) Oblique-rhombic prisms (isomnorphous with ferrous sulphate), containing seven molecules of water of crystallization, and obtained when crystallized at a temperature MANGANESIUM. 265 below 6~ C.; (2.) Rhomboidal prisms (isomorphous with cupric sulphate), containing five molecules of water of crystallization, obtained when crystallized at a temperature between 70 and 20~ C.; and (3.) Right-rhombic prisms (isomorphous with magnesium sulphate), containing four molecules of water of crystallization, and obtained when crystallized between 20~ and 30~ C. The latter salt is the one commonly met with. The crystals are permanent in the air, though slightly efflorescent In air that is dry and warm; they are soluble in nearly their own weight of cold water, but insoluble in alcohol; the aqueous solution is neutral and colorless, or has, when concentrated, a faint rose-color; its taste is astringent, and it affords, with the alkaline hydrates and carbonates, white precipitates, of which those with the hydrates gradually become yellow, and finally dark brown, by oxidation; ammoniurn sulphydrate produces a flesh-colored precipitate soluble in acids; hydrosulphuric acid throws down the same precipitate, but not before the addition of an alkaline hydrate or carbonate; tannic acid or tincture of nutgall will not act upon the solution; potassium ferrocyanide and barium nitrate produce white precipitates, and potassium ferricyanide a brown one. When a fragment of a crystal of manganous sulphate is heated with one or two drops of liquor potassme, upon platinum-foil, it yields a bluish-green fuse. Examination: Ferrous and cbuprie sulphates are detected, in the diluted solution, acidulated with hydrochloric acid, the former by a blue precipitate with potassium ferrocyanide, the latter by a black one with hydrosulphuric acid. Jfagnesiumr and alkaline sul2phates may be detected by completely precipitating the dilute solution of the salt with ammonium sulphydrate, and by testing part of the filtrate with sodium phosphate; a white, crystalline precipitate will indicate magnesium sulphate; if no reaction has taken place, another portion of the filtrate is evaporated in a porcelain capsule, and the residue heated to redness upon platinum-foil; a fixed remainder would indicatepotassium and sodi~um salts. 266 MANUAL OF CHEMICAL ANALYSIS. MORPHIA. MORPHIUM. MORPHINUM. Moriphia. Morphine. Small, brilliant, prismatic crystals, transparent and colorless, or a white, crystalline powder. Heated in a dry testtube, morphia loses its transparency and its water, and fuses to a yellow mass, which becomes white and crystalline on cooling; heated on platinum-foil, it burns away, leaving a carbonaceous residue which is wholly dissipated at a red heat. Strong sulphuric acid dissolves morphia without coloration; the solution becomes green on the addition of one drop of solution of potassium bichromate, or purple with one drop of nitric acid. Concentrated nitric acid, diluted with an equal volume of water, dissolves morphia, with a yellow color, which, after a while, or at once upon heating, becomes purple; this yellow solution in dilute nitric acid remains unchanged upon the addition of a few drops of stannous chloride (distinction from brucia, which yields a violet coloration). When a few particles of imorphia are added to a little diluted neutral liquor ferri chloridi or sulphatis, a deep-blue color is produced. This reaction takes place also in solutions of morphia, if they are not too dilute. Morphia is but sparingly soluble in cold, but a little more in boiling, water, forming a solution of a bitter taste and a faint alkaline reaction; it is almost insoluble in ether (distinction from narcotia and codeia), in benzol, and in amvlic alcohol, somewhat soluble in chloroform, and quite so in about 90 parts of cold, or 30 parts of boiling, alcohol; it dissolves freely in dilute acids, in the fixed alkaline hydrates, and in limewater, but is almost insoluble in ammonium hydrate. Dilute solutions of morphia in acidulated water are not precipitated by liquor potassEe or sodae, when added in excess (distinction from narcotia), ltor by potassium bicarbonate (distinction from the cinchona alkaloids), nor by tannic acid; they discharge the color of solution of potassium permanganate quickly, and decompose potassium iodate at once, liberating iodine, which may be extracted by agitating the solution with a little chloroform or carbon bisulphide, which, on subsiding, acquires MORPHIA. 267 a scarlet color, while the aqueous solution remains brown. The acidulated solution of morphia affords a white precipitate with potassio-mercuric iodide, and a brown one with iodinized potassium iodide. The ready solubility of morphia in liquor potassoe and soda-, and its reducing action upon iodic acid and potassium permanganate, distinguish it from almost all other vegetable alkaloids. Examination: Narcotia is indicated by a white, crystalline residue, left upon evaporating, on a watch-glass, a little pure ether agitated with a few grains of the morphia. ilineral impurities or admixtures may be detected by a fixed residue, upon complete incineration of a little of the morphia on platinum-foil, as well as by their insolubility, when about three grains of the motphia are dissolved in two fluiddrachms of boiling alcohol. Estimation of the Morphia Strength of Opium: Since the therapeutical and commercial value of opium mainly depends upon the quantity of morpllia, an examination of opium is invariably required, before its introduction into the market or its application for the manufacture of the opium alkaloids, or for medication. Among the various methods for the estimation of the morphia strength of opium, the following are simple in execution, require comparatively little time, and render approximately correct results. Stajples's Process.-One hundred grains of the powdered and dried opium are exhausted upon a filter with some warm, pure benzol, until the drops of the benzol pass through colorless. The opium is subsequently dried upon the filter until the odor of benzol has entirely disappeared, and the powder has acquired a dry appearance; it is then triturated, and rinsed into a flask with so much water as to measure 10 fluid-drachms; the mixture is macerated, with occasional agitation, for 12 hours, and is then poured upon a moistened filter, and tepid water allowed to percolate through the opium, until the washings are quite or nearly colorless. The aqueous solution is then evaporated in a beaker, upon the water-bath, at a moderate heat, to about half a fluidounce, and this is mixed with an equal bulk of alco 268 MANUAL OF CHEMICAL ANALYSIS. hol of a spec. grav. of 0.835, filtered through a small filter, and the latter washed with a little dilute alcohol. Then, onehalf of a mixture, consisting of 60 drops of aqua ammoniea and two fluid-drachms of alcohol, is added, with agitation, and the mixture allowed to stand, in a closed flask, for six hours, when the remainder of the ammonia is added, and the mixture permitted to rest again for 24 hours. The crystalline deposit in the flask being detached from its sides, the entire contents are gradually poured upon a small tared filter, and the crude, crystalline morphia washed with a few drops of cold water, and dried at a temperature not exceeding 80~ C., when the morphia is exhausted on the same filter, with a little warm pure ether, and dried again at the same temperature, until, upon repeated weighings, the weight remains unaltered. The weight indicates the percentage of morphia in the opium. Ifager-Jacobsen's Process.-Six and a half grammnes (100.321 grains) of the powdered and dried opium are triturated with three grammes (46.302 grains) of dry calcium hydrate, and so much water as to form a soft mass; this is rinsed into a tared flask of about 100 cubic centimetres (31 ounces) capacity, with so much water that the whole weighs 74- grammes (2 ounces and 3 drachms). The flask is then loosely corked, and digested, on a water-bath, with occasional agitation, for about one hour. After cooling, the flask is replaced upon the balance, and the amount of the evaporated water is exactly restored; the liquid is then passed through a small moist filter. The filtrate is collected in a test-tube, of about one inch in width and from six to seven inches in length, upon which there has been previously made a mark indicating the volume of 50 cubic centimetres (the bulk of 13 drachms of distilled water, at about 160 C.). This volume is generally obtained from the filter; in case it be a little more, the funnel is withdrawn when the filtrate reaches the mark. A mixture- of eight drops of benzol and three cubic centimetres (46k fluid-grains) of ether is then added, and the test-tube corked and agitated; which process is continued after the subsequent addition of 42 grammes (70 grains) of powdered ammoniumn chloride, until this is dissolved. The mixture is allowed to stand for three or four hours; the crystalline deposit in the test-tube is then de MORPHIA. 269 tached, if necessary, and the whole gradually transferred to a small tared and moistened filter; the crystalline mass is washed with a few drops of water, and then dried, at a temperature not exceeding 80~ C., and is subsequently washed upon the same filter with a little chloroform. Finally the filter is completely dried, at a temperature not exceeding 80~ C., and weighed. The weight of the precipitate indicates the percentage of morphia in the opium. Schneider's Process. —Ten grammes (154.340 grains) of the powdered and dried opium are exhausted with a mixture of 150 grammes (4 ounces, 61 drachms) of water, and 20 grammes (5 drachms, 9 grains) of pure hydrochloric acid; the residue, after extraction, washing, and drying, should not exceed 4.5 grammes (1 drachm, 91 grains) in weight; to the acid fluid, 20 grammes (5 drachms, 9 grains) of common salt are added, and the liquid, after standing for 24 hours, is passed through a filter, and this and the deposit of narcotia washed with a little dilute solution of common salt; aqua ammoniae is then added to the filtrate in a slight excess, and the whole allowed to stand for 24 hours more; the crystalline deposit is then collected, redissolved in diluted acetic acid, and precipitated with diluted aqua ammonie; the precipitate is collected upon a moist tared filter, washed with a little cold water, dried at a heat not exceeding 80~ C., and weighed; its weight should be not less than one gramme (15.434 grains), corresponding to 10 per cent. of morphia. Estimation of the Morphia Strength of Tincture of Opium: When tincture of opiun has to be examined for the quantity of morphia it contains, this may be ascertained by either of the two following methods: I. Twenty-one and one-third fluid-drachms (representing 100 grains of opium) of the Tinctura Opii (each fluidounce of which, when prepared according to the U. S. Pharmacopoeia, represents 37.5 grains of opium) are evaporated in a porcelain capsule or a beaker, on a water-bath, at a moderate temperature, to about one-third of the original volume; then, after standing in a cool place for twenty-four hours, the liquid is decanted from the resinous deposit, and the latter washed with 270 MANUAL OF CHEMICAL ANALYSIS. altogether about 4 fluid-drachms of cold water. The entire liquid is then reduced to about one fluidounce, by evaporation at a moderate temperature, and, when cold, is passed through a small moist filter, the capsule or beaker being washed, by means of a washing-bottle, with about one drachim of water. To the filtrate is then added an equal volume of alcohol of a spec. grav. of 0.835, and, subsequently, one-half of a mixture consisting of 60 drops of aqua ammonioe and two fluid-drachms of alcohol. The operation is then continued in the same mode as described under Staples's morphiometric process on page 267. II. Twenty-one and one-third fluid-drachms (representing 100 grains of opium) of the Tinctura Opii are diluted, in a beaker, with about nine ounces of' tepid water, and then cornpletely precipitated with a strong solution of plumbic acetate; the mixture is allowed to stand in a warm place for two hours; it is then filtered, and the precipitate washed upon the filter with tepid water, until this ceases to redden blue litmus-paper. The filtrate is next saturated with hydrosulphuric-acid gas, and allowed to -stand for one hour, when it is filtered and washed again. Then so much of a solution of potassium bicarbonate (free from carbonate) is added to the filtrate as to render it slightly alkaline; it is then filtered, and the precipitate washed with a little carbonic-acid water; the filtrate is then over-satnrated with acetic acid, and evaporated in a tared porcelain capsule, on a water-bath, to about three ounces by weight; when nearly cold, it is completely precipitated with a solution of one part of potassium carbonate in two parts of water, and is then allowed to stand for 24 hours, when the crystalline deposit is collected upon a small tared filter, and washed with a few drops of cold water, or until this ceases to change the color of red litmus-paper at once. The precipitate is dried on the filter at a temperature not exceeding 80~ C., and is then exhausted on the filter with a little warm, pure ether, and subsequently dried again at the same temperature. In both tests the precipitate, when completely dry, should weigh at least 10 grains, indicating the employment of an opium containing 10 per cent. of morphia, and a morphia strength of the tincture amounting to 3.75 grains in each fluidounce. MORPHIA. 271 MIORPHIAE ACETAS. MORPHIUM SEU MORPHINUhI ACETICUM. Acetate of Morphia or Morphine. Aforphia Acetate. A white or nearly white powder, with a feeble odor of acetic acid, and permanent in the air; when heated upon platinum-foil, it fuses, and is Wholly dissipated at a red heat. It remains colorless when moistened with concentrated sulphuric acid, and dissolves in concentrated nitric acid, with a scarlet color. Morphia acetate is soluble in about 24 parts of cold water, acidulated with a few drops of acetic acid, and freely soluble in boiling water, and in diluted acids; it is little soluble in cold, but more so in warm, alcohol, but almost insoluble in ether. Its aqueous solution has a very bitter taste and a slightly acid reaction; it is rendered turbid by tannic acid, but becomes transparent again upon the addition of diluted sulphuric acid (evidence of the absence of narcotia); it is not permanently precipitated by potassium hydrate, when added in a slight excess (distinction from most alkaloids), nor by potassium bicarbonate (further distinction from narcotia and from the cinchona alkaloids), and assumes a greenish-blue coloration with dilute solution of ferric chloride. MORPHIi HYDROCHLORAS. MORPHIUJI SEU MORPHINUM HYDROCHLORICUM. MORPHIlE MURIAS. Hydrochlorate of Alorphia or Morphine. AiorphicT Hydrochloride. Colorless, transparent, flexible, acicular crystals, of a silky lustre, or a crystalline powder, containing 14 per cent. of water of crystallization, which evaporates at a moderate temperature. Heated upon platinum-foil, morphia hydrochloride fuses, and, at a higher temperature, burns away without residue. Miorphia hydrochloride is soluble in 20 parts of cold, and in 272 MANUAL OF CHEMICAL ANALYSIS. nearly its own weight of boiling, water, and in 60 parts of cold, and 10 parts of boiling, alcohol. Its aqueous solution is neutral, has a bitter taste, and assumes a yellowish-red coloration upon the addition of strong nitric acid, with gentle heating, and a bluish one with dilute solution of ferric chloride; it renders no-permanent turbidity with dilute liquor potassae in a slight excess, but is precipitated by ammonium hydrate. When acidulated with hydrochloric acid, the solution yields no precipitate with tannic acid, nor with potassium bicarbonate (distinction from narcotia and from the cinchona alkaloids). With argentic nitrate, the aqueous solution of morphia hydrochloride gives a white, curdy precipitate, insoluble in nitric acid, but soluble in aqua ammoniie, which solution, when heated in a test-tube, separates metallic silver. When a little dry morphia hydrochloride is added to a mixture of two parts of concentrated sulphuric acid and one part of water, in a small test-tube, no change of color of the liquid takes place, either at common temperatures, or when gently warmed by immersing the test-tube in hot water (evidence of the absence of salicin and other bitter substances); when this liquid is divided into two portions, and one drop of strong nitric acid is added to the one part, a red coloration occurs, and on adding a trace of potassium bichromate to the other part, only a slight yellowish-green coloration takes place. Morphia hydrochloride dissolves in chlorine-water, with a yellowish color, which becomes brown upon addition of aqua amnmonioe (distinction from quinia, which yields an emeraldgreen coloration). 0TORPHIIE SULPHIAS. MORPHIUM SEU MORPHINUM SULPHURICUM. Sulphate of Morphia or Morphine. Morphia Sulphate. Colorless, transparent, fasciculate, feathery crystals, permanent in the air; they contain about 14 per cent. of water, of which 12 per cent., water of crystallization, are given off at NICOTIA. 273 1007 C. When heated upon platinum-foil, morphia sulphate fuses, and burns away without residue. Morphia sulphate is soluble in twice its weight of cold, and less than its own weight of boiling, water (distinction from quinia sulphate); it is less soluble in alcohol, and almost insoluble in ether and in chloroform. Its aqueous solution is neutral and very bitter; it gives no permanent precipitate with potassium hydrate when added in a slight excess, nor with potassium bicarbonate (distinction from the cinchona alkaloids), but a white one with ammonium hydrate or carbonate. It gives a bluish reaction with ferric chloride, and a white precipitate, insoluble in acids, with barium chloride. Morphia sulphate dissolves in strong sulphuric acid without coloration, even when gently warmed by dipping the test-tube in warm water (evidence of the absence of salicin and other bitter glucosides); it dissolves in concentrated nitric acid with a yellowish-red coloration (distinction from quinia). When dissolved in a little chlorine-water, morphia sulphate yields a greenish-yellow solution, which becomes dark-brown upon addition of aqua ammonim (further distinction from quinia, which yields an emerald-green reaction). NICOTIA. NICOTINUM. Nicotine. Nicotia. A colorless or nearly colorless, oily, and volatile liquid, of 1.027 spec. grav., with a pungent odor, resembling that of tobacco, and an acrid, burning taste. By exposure to the air, it becomes gradually brown and thick; when heated, it volatilizes, forming irritating vapors, which, when ignited, burn with a bright flame. When dropped into concentrated sulphuric acid, it dissolves, with a red color, and, when one drop of solution of potassium bichromate is added, the solution becomes brown, and subsequently green. Nicotia produces white fumes with hydrochloric and acetic acids, precisely like ammo18 274 MANUAL OF CHEMICAL ANALYSIS. nium hydrate; when dropped into concentrated hydrochloric acid, and heated, it dissolves with a deep-violet color, and likewise in nitric acid, with an orange-yellow color. Nicotia sinks when dropped into water (distinction from conia, which floats); it is miscible with water, alcohol, ether, carbon bisulphide, and chloroform, and with most fixed and essential oils; its solutions have an alkaline reaction, and an acrid, burning taste; they are precipitated by solutions of tannic acid and of potassio-mercuric iodide; the alcoholic solution should yield no turbidity with diluted sulphuric acid (evidence of the absence of ammonium hydrate). The aqueous solution of nicotia, when applied to the eye, causes the pupil alternately to dilate (mydriasis) and to contract (stenocoriasis). OLEUX AXYGDALARUII AMARARUX. Oil of Bitter Almonds. A thin, colorless, or golden-yellow liquid, of great refractive power, and of the odor of bitter almonds, when triturated with water. Exposed to the air, it greedily absorbs oxygen, with the formation of crystals of benzoic acid; its spec. grav. is from 1.04 to 1.06; its boiling-point, 180~ C. MWhen dropped into water, oil of bitter almonds sinks, but dissolves upon shaking, unless too much oil has been used. When a few drops of liquor potassae are added to its aqueous solution, and afterward one or two drops of ferrous chloride or sulphate, and finally, after agitation, a slight excess of hydrochloric acid, there will appear a blue coloration, and, after a while, a blue precipitate. Oil of bitter almonds is miscible, in all proportions, with alcohol, ether, chloroform, carbon bisulphide, and essential and fatty oils; it is also soluble in concentrated nitric acid, without color, and without the evolution of nitrous fumes; it forms a thick, crimson liquid with concentrated sulphuric acid. Among the several compounds of which oil of bitter almonds consists, it contains from 3 to 14 per cent. of hydrocyanic OLEA. 275 acid, partly free and partly combined; the crude oil derived by distillation, without further rectification, generally is the richest in acid. Estimation of the Available Quantity of Hydrocyanic Acid in Oil of Bitter Almonds: 1. Fifty grains of the oil are mixed with half an ounce of strong alcohol in a small flask; then four ounces of water are added, and 50 drops of liquor potassse, or so much as to render the liquid strongly alkaline. Volumetric test-solution of argentic nitrate is then delivered into this liquid (Fig. 77), with constant stirring, until the ensuing precipitate ceases to be redissolvedl, and therefore a slight permanent turbidity occurs. The quantity of argentic nitrate employed represents exactly half the amount of hydrocyanic acid, and has, therefore, to be multiplied by four, to obtain the percentage. 2. Another method consists in dissolving 50 grains of the oil in half a fluidounce of alcohlol, in a small flask, and adding about four ounces of water; to this solution is then added a solution of 30 grains of argentic nitrate in four A= __ = fluid-drachms of aqua ammo- FIG. 7T. nice; the mixture is then gently warmed to about 50~ C., and, after repeated agitation, an excess of nitric acid is added, and the whole gently warmed by immersing the flask in hot water. The precipitate of argentic cyanide is collected upon a tared and moist filter, washed until the washings cease to redden blue litmus-paper, and then dried and weighed. The number of grains of the weight of the 276 MANUAL OF CHEMICAL ANALYSIS. dry argentic cyanide being divided by five, the quotient, multiplied by two, gives the percentage of anhydrous hydrocyanic acid contained in the oil. Examination: Alcohol may be detected in oil of bitter almonds by agitating it with three times its volume of concentrated nitric acid, and subsequently warming the mixture by dipping the testtube into hot water. No reaction takes place with pure oil; but, if it has anll admixture of more than three per cent. of alcohol, effervescence will occur, with disengagement of yellowish nitrous vapors. Chloroform, as well as alcohol, call be detected by submitting about two drachms of the oil to distillation from a waterbath, cooling the receiving test-tube in ice-water (Fig. 78). The boiling-point of the oil being at 1800 C., only admixtures volatile at or below the boiling-point of water will distil, with FIG. 78. but small traces of the constituents of the oil. The obtained distillate is mixed with a little iodine-water; if chloroform be present, and no alcohol, it will absorb the iodine, and separate, with a rose-color. The colorless, aqueous liquid is decanted, and then warmed by dipping the test-tube in warm water; one drop of solution of iodinized potassium iodide is added, and then one drop of liquor potasae, or so many as nearly to decolorize the liquid. If alcohol be present, minute yellow crystals OLEA. 277 of iodoform will be produced (Fig. 79), which, after subsiding, in a conical glass, may be recognized by the examination of the sediment under the microscope. Nitrobenzol may be detected by dissolving 15 grains of fused potassium hydrate in about two fluid-drachms of alcohol; the solution may be aided by dipping the test-tube into hot water; when it is complete, from 15 to 20 drops of the oil are added, and the heating continued for a minute; if FIG. 79. the oil be pure, the mixture will remain colorless or nearly so, and will form, on cooling, a white, crystalline deposit of potassium benzoate; if it is contaminated with nitrobenzol, the liquid will assume a dark-brown color. Or the oil may be tested by agitating about one drachmi of it with half a drachm of fused potassium hydrate. If nitrobenzol is present, the yellow color of the oil will give place to a red tint, which passes into green, if much nitrobenzol is present; the green color disappears after about twelve hours and returns to the red tint. Essential Oils. —Adulteration with cheaper essential oils, as well as with nitrobenzol, may be detected by the property of oil of bitter almonds to dissolve in a concentrated aqueous solution of sodium bisulphite when added drop by drop and agitated; whereas such admixtures remain undissolved, floating upon the aqueous solution after dilution with a little tepid water. OLEUM SINAPIS. Volatile Oil of Mustard. A colorless or pale-yellow liquid, of a most penetrating, pungent odor, and of 1.01 to 1.015 spec. grav.; when dropped into water, it sinks slowly, and dissolves in about 50 parts of it, which solution forms a black precipitate, when heated with a few drops of solution of argentic nitrate. 278 MANUAL OF CHEMICAL ANALYSIS. Mustard oil is miscible with alcohol, ether, chloroform, carbon bisulphide, and benzol, and with fatty and essential oils; it suffers decomposition with concentrated nitric acid, with the evolution of nitrous vapors, and the formation of a resinous residue. When dropped into concentrated sulphuric acid, mustard oil dissolves, without color, and without the evolution of heat, and when mixed with concentrated sulphuric acid, in the proportion of one part of oil to three parts of acid, taking care that the mixture is kept cool, sulphurous acid is evolved, and, after 12 hours, a colorless or but slightly brown, thick liquid or crystalline mass is formed, devoid of the odor of mustard oil. Examination: Admixtures of essential oils, cazrbon bisulphide, nitrobenzol, and alcohol, are indicated by becoming warm and dark-colored when about five or sit drops of the oil are added to about 50 or 60 drops of concentrated sulphuric acid, in a dry test-tube. Admixtures of alcohol, benzol, and other hydrocarbons, are also indicated when two or three drops of the oil are allowed to fall into a test-tube, filled about one-third with cold distilled water; they should sink slowly to the bottom, remaining clear and transparent, until, after gently inclining the tube two or three timaes, they become opalescent. When contaminated with only a few per cent. of the above adulterations, the drops lose their transparency, and become opalescent, as soon as they fall into the water. PLUMBI ACETAS. PLUMBUM ACETICUM. Acetate of Lead. Sugar of Lead. Plumbio Acetate. Colorless, transparent, brilliant prisms or plates, or, as generally met with, heavy, compact crystalline masses, somewhat resembling loaf-sugar, having an acetous odor and a sweet, astringent taste; they contain three molecules (14.21 per cent.) of water of crystallization, and effloresce slowly and absorb car PLUMBUM. 279 bonic acid when exposed to the air; they become black when in contact with gaseous or dissolved hydrosulphuric acid. When gently heated, plumbic acetate fuses at 75.5~ C., loses water and acetic acid, and is decomposed at a higher temperature, leaving a black residue, which is reduced, at a red heat, to plumbic oxide or to metallic lead. Plumbic acetate is soluble in about two parts of cold, and in half its weight of boiling, water, and in eight parts of alcohol, but insoluble in ether and in chloroform; its solution in water has generally a slightly turbid appearance froml traces of plumbic carbonate, which, however, disappears upon the addition of acetic acid; the aqueous solution has a feeble acid reaction, forms white precipitates with the alkaline hydrates (soluble in excess of potassium and sodium hydrates), with the alkaline carbonates, and with sulphates and chlorides, a yellow one with iodides, and a black one with hydrosulphuric acid and with sulphides. When completely precipitated by sodium chloride, the colorless filtrate will assume a deep-red tint with a few drops of solution of ferric chloride. Examination: Calcium and barium acetates may be detected, in a solution of 20 grains of the plumbic acetate in one ounce of warm water, by precipitating it with 20 drops of concentrated hydrochloric acid; the filtrate is completely precipitated with hydrosulphuric acid, is filtered, and then over-saturated with sodium carbonate, and gently warmed; a white turbidity would indicate calcium or barium salts. Copper is indicated by a blue coloration' of the solution of plumbic acetate, when precipitated with aqua ammonike. PLJUMBI CARBONAS. PLUMBI SUBCARBONAS. PLUMBUM CARBONICUM. CERUSSA. Carbonate or Subcarbonate of Lead. White Lead. Basic Plumbie Carbonate. A heavy, white, opaque powder, or friable lumps, which are blackened by hydrosulphuric acid. Heated upon charcoal, 280 MANUAL OF CHEMICAL ANALYSIS. before the blow-pipe, plumbic carbonate turns yellow, fuses, and is finally reduced to soft, malleable metallic globules. It is insoluble in pure water, but somewhat soluble in water containing much carbonic acid or alkaline bicarbonates; it is wholly dissolved, with effervescence, in diluted acetic and nitric acids, rendering colorless solutions, of a sweet, astringent taste; these solutions yield white precipitates with dilute sulphuric and hydrochloric acids, and with soluble sulphates and chlorides; they also give a white precipitate with liquor potasse or sodae, soluble in an excess of the precipitant, a yellow one with potassium iodide, and a black one with hydrosulphuric acid. Examination: Admixtures of barium, calcium, and plumbic szulphates, remain behind, upon solution of the white lead in dilute nitric acid. Their quantity may be ascertained by dissolving 100 grains of the sample in a sufficient quantity of warm diluted nitric acid, and by collecting and washing the insoluble residue upon a tared filter; when.completely dry, the weight indicates the percentage of such admixtures. If the nature of the admixture has to be ascertained, the residue is transferred to a flask, and is digested, for some days, with occasional agitation, with a solutiOn of ammonium sesquicarbonate; if plumbic sulphate be present, it is decomposed, and plumbic carbonate formed; as an evidence of the presence of the former, part of the supernatant liquid may be acidulated with nitric acid, and tested with barium nitrate for sulphuric acid. Admixtures of calcium carbonate or phosphate, barium carbonate, and oxide of zinc, are more or less soluble in nitric acid. In order to detect and to distinguish them, the nitricacid solution of the sample is freely diluted with water, and is subsequently saturated and completely precipitated with hydrosulphuric-acid gas; it is then filtered, and warmed, to expel the excess of gas, and a small portion of the solution is oversaturated with sodium' carbonate; an ensuing white precipitate will confirm the above admixtures; in order to ascertain their nature, the rest of the solution is nearly neutralized with a few drops of liquor sodme and then tested, in separate portions, with solution of calcium sulphate for barium, with oxalic PLUMBUM. 281 acid, after previous addition of a little sodium acetate, for calcium, and by addition first of sodium acetate and subsequently of ammnonium sulphydrate, for zinc. PLUMBI IODIDUM. PLUMIBUM IODATUM. Iodide of Lead. Plumbic Iodide. A bright-yellow, heavy, inodorous powder, when obtained by precipitation, or shining, golden-yellow, flexible scales, when crystallized; when heated in a dry test-tube, plumbie iodide turns red, and fuses to a thick reddish-brown liquid, which congeals, on cooling, to a yellow mass; at a stronger heat, it is decomposed, with the evolution of violet vapors; and when heated with exsiccated sodium carbonate, on charcoal, before the blow-pipe, it is entirely reduced to metallic globules. Plumbic iodide is soluble in about 1,250 parts of cold, and 194 parts of boiling, water, and also, to a slight extent, in alcohol; a hot saturated aqueous solution, on cooling, deposits the salt in brilliant yellow scales; it is readily soluble in acetic acid, in liquor potassoe or sodre, in concentrated solutions of the alkaline or earthy iodides, in warm solution of ammonium chloride, and in solution of sodium hyposulphite, from all which solutions hydrosulphuric acid precipitates black plumbic sulphide. When shaken in chlorine-water, plumbic iodide suffers partial decomposition, and yields a filtrate from which chloroform or carbon bisulphide will extract iodine, with a red color. When boiled with solutions of alkaline or earthy carbonates, it is decomposed, forming iodides and plumbic carbonate. When boiled with granular or powdered iron or zinc, plumbic iodide is likewise decomposed, forming soluble iron or zinc iodide and metallic lead. 282 MANUAL OF CHEMICAL ANALYSIS. PLUMBI NITRAS. PLUMBUM NITRICUM. Nitrate of Lead. Plumbic Nitrate. Colorless, transparent or opaque, anhydrous, octahedral crystals, permanent in the air. Heated in a dry test-tube, the crystals deflagrate, emit yellow nitrous vapors, and leave a residue of plumbic monoxide. Plumbic nitrate is soluble in 971 parts of cold water, but less soluble in alcohol. Its aqueous solution is neutral, has a sweet, astringent taste, and gives a white precipitate with sulphuric or hydrochloric acid, and with solutions of sulphates or chlorides, a yellow one with potassium iodide, and a black one with hydrosulphuric acid. When triturated with concentrated sulphuric acid, and heated, the salt evolves red nitrous fumes. Examination: Barium nitrate may be detected in the filtrate from the aqueous solution of the salt, after complete precipitation with hydrosulphuric acid, by over-saturating it with sodium carbonate; a white precipitate would indicate barium. Copper may be detected, in the aqueous solution of the salt, by completely precipitating it with sodium sulphate, and by testing the filtrate with an excess of ammonium hydrate, when copper will be indicated by a bluish color of the liquid. PLUIJMBI OXIDUM. PLUMBUM OXYDATUM FUSCUM. LITHARGYRUfM. Oxide of Lead. Litharge. Plumbic Monoxide. Small scales or heavy masses, of a brick-red color and a foliaceous fracture, or a heavy powder of the same color, devoid of taste and odor. It fuses at a red heat, and, when heated upon charcoal, is reduced to the metallic state. Plumbic monoxide is but sparingly soluble in water, imparting thereto a feeble alkaline reaction; it is soluble in PLUMBUM. 283 warm solutions of the fixed alkaline hydrates, and in diluted nitric and acetic acids, without effervescence or residue; it slowly absorbs carbonic acid from the atmosphere, and contains the more carbonate the longer it has been exposed to the air; from this cause, when very old, it becomes more or less effervescent with acids. The nitric-acid solution of plumbic monoxide yields white precipitates with dilute sulphuric and hydrochloric acids, with solutions of sulphates and chlorides, and with the alkaline hydrates, which latter, ammonium hydrate excepted, redissolve the precipitate, when added in excess; it gives a black one with hydrosulphuric acid, and, when neutral, a yellow one with potassium iodide. Examination: Plzumbic carbonate and red oxide are detected, when a small quantity of the litharge is triturated with a little water, and the mixture is added, drop by drop, to concentrated nitric acid, in a test-tube; carbonate is recognized by effervescence; red oxide by a brown residue, insoluble in an excess of acid, with gentle warming, but soluble upon the addition of a little oxalic acid or sugar; if this residue, however, does not dissolve, an adulteration with powdered silicates, crude ferric oxide, etc., is indicated. Silicates are also indicated by a white turbidity or a flocculent precipitate, occurring in the solution after the addition of the oxalic acid, in the preceding test. Oxides of zinc and alkaline earths may be detected by mixing the nitric-acid solution with three times its volume of hydrosulphuric acid, or so much as completely to precipitate the lead; the filtrate is evaporated to half its volume, and one portion of it is over-saturated with sodium carbonate; an ensuing white precipitate would indicate oxides of zinc, calcium, or barium; the other part is neutralized with liquor sode, and tested, in separate portions, with sodium acetate, and subsequent addition of hydrosulphuric acid, for zinc; with ammonium oxalate for calcium, and with calcium sulphate for barium. Copper and Sulphates.-About 30 grains of the powdered litharge are digested, for one hour, with occasional agitation, in about half an ounce of a mixture consisting of equal parts of aqua ammoniva and dilute solution of ammonium sesqui-car 284 MANUAL OF CHEMICAL ANALYSIS. bonate; a bluish tint, in the obtained filtrate, would indicate copper, and a white precipitate, when slightly over-saturated with diluted nitric acid, and subsequently tested with barium nitrate, would show sulphate. Mfetallie ]-ead.-About 20 grains of the litharge are digested in a test-tuble, with occasional agitation, for half an hour, with a solution of plumbic nitrate; a few drops of the decanted liquid are then introduced into a little water, to which previously have been added a few drops of sulphuric-acid mucilage of starch, and a few drops of solution of potassium iodide. If the sample contains even traces of metallic lead, this gives rise to the formation of plumbic nitrite, which will decompose the potassium iodide, with the liberation of iodine, which at once produeces a blue color with the starch. PLUNBI OXIDUIMl RUBRUM. PLUMBUM OXYDATUM RUBRUM. MINIUM. Red Oxide of Lead. Afinimun. Triplumbic Tetroxide. Plumbic Plumbate. A heavy, orange-red powder, which becomes dark when heated, but regains its original color on cooling. Heated upon charcoal, before the blow-pipe, it fuses, and is reduced to metallic globules. Warm diluted nitric or acetic acid will dissolve red oxide of lead only partially, leaving a brown residue, which is soluble, however, upon the addition of a little oxalic acid or sugar. A slight remaining turbidity, of a whitish aspect, is due to silicic acid, with which red oxide of lead is generally more or less contaminated; any insoluble red or brown residue, however, would indicate impurities. The impurities and admixtures which red oxide of lead is liable to contain, and the methods of detecting them, are the same as mentioned and described under litharge, on the preceding page. POTASSIUM. 285 POTASSII ACETAS. POTASSIUM SEU KALIUM ACETICUM. Acetate of Potassium. Potassium Acetate. A snow-white, very deliquescent salt, of a foliaceous or fibrous satiny appearance, unctuous to the touch, and of a warm, pungent, saline taste; it fuses at about 280 C., and is decomposed at a higher temperature, leaving behind a mixture of carbon and potassium carbonate. Potassium acetate is soluble in its own weight of cold water, in 4 parts of alcohol, and in 3 parts of glycerin; its dilute aqueous solution assumes a deep red color with one or two drops of solution of ferric chloride, and renders a white granular precipitate with solution of sodium bitartrate or of tartaric acid. Potassium acetate disengages the vapor of acetic acid with concentrated sulphuric acid, and the vapor of acetic ether when heated with a mixture consisting of equal parts of alcohol and sulphuric acid. Examination: JMetals are detected in the aqueous solution by a dark coloration or precipitate with hydrosulphuric acid; if such reaction takes place, the solution of the salt may be acidulated with a few drops of hydrochloric acid, and tested with potassium ferrocyanide; copper will be indicated by a reddish coloration, iron by a blue one. lCartrates, sulphates, and chlorides, are indicated by the occurrence of a turbidity when a concentrated aqueous solution of the salt is dropped into strong or absolute alcohol; the latter two are also recognized in the diluted solution, acidulated with nitric acid, by white precipitates when tested in separate portions with argentic nitrate and barium nitrate respectively. For Volumetric Estinmation, see page 58. 286 MANUAL OF CHEMICAL ANALYSIS. POTASSII BICARBONAS. POTASSIUM SEU KALIUM BICARBONICUM. Bicarbonate of Potassium. Potassium Bicarbonate. Transparent, colorless crystals, having the form of i rregular eight-sided prisms with two-sided summits; they are permanent in the air, but, when exposed to a red heat, they lose 30.7 per cent. of their weight, comprising half their quantity of carbonic acid and the whole (6 molecules, or 9 per cent.) of their water, and return to the state of carbonate. Potassium bicarbonate dissolves in 4 to 5 parts of cold water, forming a slightly alkaline solution which effervesces with acids and evolves carbonic-acid gas when heated to boiling; it gives a white granular precipitate with excess of tartaric acid, but no precipitate with magnesium sulphate unless when heated. It is almost insoluble in alcohol. One drachm of potassium bicarbonate requires for exact saturation 42 grains of citric, or 45 grains of tartaric, acid. For Volumetric Estimation, see page 58. Examination: Carbonate may be detected in the cold aqueous solution by means of magnesium sulphate, and in another portion by mercuric chloride; a white precipitate with the first reagent, solu-'ble upon addition of ammonium chloride, and a brick-red one with the second, would indicate carbonate. Other irAnpurities.-The aqueous solution is slightly oversaturated with diluted nitric acid; a white turbidity, occurring immediately or after a while, would indicate silicates; the solution, if necessary, is filtered, and tested in separate portions with argentic nitrate for chloride, and with barium nitrate for sulph/ate; a white turbidity with argentic nitrate, gradually turning dark, would indicate potassium hyposulphite; in this case, as a confirmatory test, 10 grains of tho potassium bicarbonate may be dissolved in one drachm of water, and the solution slightly over-saturated with acetic acid; then a few drops of mucilage of starch, and subsequently of solution of iodinized potassium iodide, are added drop by drop; the first drops of the latter reagent should at once produce the blue reaction, POTASSIUM. 287 which will not take place immediately if potassium hyposulphite be present in the salt. -letals are detected by testing two portions of the solution of potassium bicarbonate, one of which is over-saturated by means of acetic acid, with hydrosulphuric acid: a dark reaction in either instance would indicate the presence of metallic impurities; if hyposulphite be present, a white turbidity will take place in the acid solution. POTASSII BICHROXDAS. POTASSIUM SEU KALIUM BICHROMICUM. KALIUM CHROMICUM RUBRUM. Bichromate of Potassium. Potassium Bichromate. Large, transparent, orange-red, four-sided, tabular crystals, anhydrous and permanent in the air; exposed to heat, they fuse below redness, and are decomposed at a red heat with the evolution of oxygen, leaving a residue consisting of green chromic oxide and yellow potassium chromate; these may be separated by dissolving the latter in water. Potassium bichromate is soluble in 10 parts of cold, and in 21 parts of boiling, water, yielding an intensely orange-yellow solution, with a cooling, bitter taste, and an acid reaction; the solution becomes lemon-yellow with the alkaline hydrates and carbonates, and green or almost colorless, with the formation of a brown precipitate, when heated with reducing agents; it forms insoluble colored bichromates and chromates with the solutions of most metallic salts. When heated with concentrated hydrochloric or sulphuric acid and a little alcohol, a vehement reduction takes place, and the liquid acquires a deep green color. A concentrated solution of the salt gives a white, granular precipitate with a concentrated solution of sodium bitartrate. Examination: Sulphate may be detected by heating to boiling a mixture 288 MANUAL OF CHEMICAL ANALYSIS. of the aqueous solution with an equal volume of concentrated hydrochloric acid and a few drops of alcohol; when subsequently diluted with water and tested with barium chloride, a white precipitate will ensue if sulphate be present. Chloride may be detected when the aqueous solution of the salt is mixed with about one-third of its volume of concentrated sulphuric acid, and when afterward a little alcohol is added; the mixture will become green, with spontaneous ebullition; it is then heated, and subsequently diluted with water, and tested with argentic nitrate for chloride. POTASSII BITARTRAS. POTASSIUM SEU KALIUM BITARTARICUM. TARTARUS DEPURATUS. CREMOR TARTARI. Bitartrate of Potassium. Cream of Tartar. Potassium Bitartrate. White, semitransparent, hard, prismatic crystals, or aggregated groups of crystals, or a white, gritty powder, permanent in the air, and having a spec. grav. of 1.97, a sour taste and an acid reaction. When exposed to heat, in a porcelain crucible, potassium bitartrate is decomposed, with the evolution of empyreumatic, inflammable vapors, leaving a black residue of carbon and pure potassium carbonate; this residue, when dissolved in a little water, gives a filtrate which effervesces with acids, and forms a white, granular precipitate with an excess of tartaric acid. Potassium bitartrate is soluble in from 18 to 20 parts of boiling water, in about 200 parts of water of 15~ C., and in 250 parts of water of 10~ C.; it is insoluble in alcohol, but dissolves wholly in hydrochloric acid, in dilute solutions of the alkaline hydrates and carbonates, of boracic acid, and of sodium biborate. Examination: Insoluble admixtures (like terra alba, and similar crude adulterations) are indicated by a residue left when small sam POTASSIUM. 289 ples of the powder are dissolved separately in warm, diluted liquor potassae, and in dilute hydrochloric acid. Sulphates and chlorides are detected by agitating about one drachm of the salt in one ounce of warm water, and by testing portions of the clear liquid, when cool, and after the addition of a few drops of nitric acid, with barium nitrate for sulphates, and with argentic nitrate for chlorides. Alumn?.-An adulteration of powdered cream of tartar with alum is at once indicated by a greater solubility of the salt in water, by its intumescence upon incineration, and by the incomplete solubility of the fused residue in water, as also by the odor of ammoinia, and the production of white fumes from a glass rod, moistened with acetic acid, when the powder is heated in liquor potasse, and by the formation of a white precipitate, when a few drops of this alkaline solution are allowed to fall into a dilute solution of ammonium chloride. letals may be detected in the rest of the solution of the preceding test, by hydrosulphuric acid. Calcieum and iron salts are detected when about 10 grains of the salt are dissolved in one ounce of aqua ammonite, by testing the solution, in two portions, with oxalic acid and with ammonium sulphydrate; a white precipitate with the former will indicate salts of calcium, and a dark coloration or turbidity with the latter reagent, iron. The presence of calcium salts in potassium bitartrate, if it be free from aluminium salts, may be confirmed by dissolving five grains of the potassium bitartrate, with five grains of crystallized sodium carbonate, in about four drachms of boiling water; a complete and clear solution must take place, as a remaining white turbidity would prove the presence of calcium salts. Iron salts may be confirmed, in a hydrochloric-acid solution of the salt, by a blue reaction with potassium ferro-cyanide. For V'olumetric Estimation, see page 58. 19 290 MANUAL OF CHEMICAL ANALYSIS. POTASSII BROMIDUM. POTASSIUM SEU KALIUM BROMATUM. Bromide of Potassium. Potassium Bromide. Anhydrous, colorless, semitransparent, cubical crystals, sometimes elongated into prisms, or flattened to plates, permna nent in the air, and of a spec. grav. of 2.415; when exposed to heat, they decrepitate, and fuse at a little below a red heat, without decomposition. When a few grains are triturated and subsequently heated, in a dry tube, with a little potassium bisulphate, yellowish-red vapors of bromine are evolved. Potassium bromide is soluble in about three parts of cold, and in its own weight of boiling, water, but only sparingly in alcohol; its aqueous solution has a strong saline taste, is neutral, and, when dropped into a very dilute solution of argentic nitrate, causes a yellowish-white curdy precipitate, which is insoluble upon addition of nitric acid, but soluble in an excess of ammonium hydrate (distinction from. argentic iodide); when dropped into a very dilute solution of mercuric chloride, no reaction takes place (additional distinction from potassium iodide); it gives a white, granular precipitate with a saturated solution of sodium bitartrate. Potassium bromide and its solution may also be distinguished from the iodide by adding to the:solution a little mucilage of starch, and subsequently a few drops of chlorinewater; the solution of bromide becomes light yellow; that of iodide will at once assume a deep-blue color. Examination: JMoisture which may be contained in the crystals, as well as in the granular form of the salt, is recognized, and may be determined, by the loss of weight when the salt is dried at about 80~ C. Potassium carbonate is detected by a white turbidity occurring upon the addition of a little of the concentrated solution of the salt to lime-water. Sulphates may be detected, in the aqueous solution, acidulated with a few drops of diluted nitric acid, by a white precipitate with barium nitrate. POTASSIUM. 291 Potassium 6romate is detected by a red color ensuing upon the addition of concentrated hydrochloric acid to the aqueous solution of the salt. Potas.sium and sodium chlorides are distinguished from potassium bromide, and may be recognized by adding some chlorine-water to the aqueous solution of the salt; if this is bromide, the mixture assumes at once a yellow color, which, however, will be caused to disappear from the aqueous solution, and be completely taken up, by chloroform, ether, or carbon bisulphide, when agitated with the solution. None of these reactions will take place with potassium or sodium chloride. If an admixture of potassium chloride, or other salts, be suspected, the purity of the sample may be ascertained by preparing a solution of 10 grains of the dry, crystallized salt in one ounce of water, acidulated with a few drops of diluted nitric acid, and completely precipitating it with a solution of argentic nitrate; the precipitate is collected upon a moist double filter, both being of the same paper and the same size, is washed, dried, and, when completely dry, weighed, the one filter serving to counterpoise the other one, which contains the precipitate. If the salt was pure potassium bromide, the obtained argentic bromide should weigh 15.77 grains; if it contained potassium or sodium chloride, the weight will be greater in proportion to the amount of those admixtures, since their molecular weights are higher; 10 grains of potassium chloride, for instance, would give 19.21 grains of argentic chloride. The same test may also be used to indicate the purity of the bromide, by ascertaining the quantity of,argentic nitrate required to precipitate completely a certain weight of potassium bromide, 10 grains of which require 14.3 grains of argentic nitrate for precipitation. An additional and sensible mode, of detecting an admixture of chlorides is the following: One drachm of the potassium bromide is triturated with one drachlm of potassium bichromate, the powder is introduced into a small flaslk, and six fluiddrachms of concentrated sulphuric acid are added. The mixture is then submitted to distillation at a gentle heat; the delivery-tube leads into about one fluidounce of aqua ammonia fortior, contained in a test-tube which is kept cool in ice-water 292 MANUAL OF CHEMICAL ANALYSIS. (Fig. 80). Bromine distils over, and is dissolved by the ammonium hydrate without color; but, if chlorides are present, chloro-bromic acid is produced, distils over, and forms yellow FIG. 80. ammonium chromate, which imparts a yellowish color to the aqua ammonite, and indicates the presence of chlorides. For Volumetric Estimation, see page 62. POTASSII CARBBONAS CRIUDA. POTASSIUM SEU KALIUM CARBONICUM CRUDUM. C'ude Carbonate of Potassium. PearlasTh. White masses, or a coarse granular powder intermingled with smaller lumps, somewhat deliquescent, and of a burning, alkaline taste. Water extracts from pearlfash the potassium carbonate and hydrate, and the soluble impurities, the greater part of the impurities remaining behind (sulphates, chlorides, silicates, phosphates, and carbonates of potassium, sodium, calcium, and aluminium); the filtered solution effervesces with acids, and renders a white, granular precipitate with an excess of tartaric acid. POTASSIUM. 293 The examination of pearlash consists ~f~ l-51 1l ~in the determination of the quantity of soluble alkaline carbonate and hydrate, or the available potassium oxide. Approximate Estimation: Il ||1114i'l | Three and a half drachms of commer-'t' l1!cial pearlash, when successively exhausted with from'four to six ounces of warm water, render a solution which must neutralize at least two drachms of sulphuric![l l'l!l acid of 1.843 spec. grav. Volumetric Estimation: Five grammes (77.170 grains) of' the pearlash are completely exhausted with two or three fluidounces of tepid water; the solution is collected in a beaker-glass, is colored blue with a few drops of neutral l I!ll',')l litmus-solution, and heated to near boilIfllllll; ing; then oxalic-acid test-solution (page hllt li!la 56) is carefully added from a burette (Fig. hI Illll l!81), with constant stirring, until the blue tint begins to appear violet; the liquid is heated once more to boiling, and, if necessary, test-solution is once more added, drop by drop, until the violet tint appears again distinctly. The number of cubic centimetres of the test-solution used, FIG. 81. when multiplied by 0.472, gives at once the percentage of potassium oxide contained in the pearlash. When the quantity of carbonate has to be determined, this may be done by testing 50 or 100 grains of the pearlash by the method described on page 60. 294 MANUAL OF CHEMICAL ANALYSIS. POTASSII CARBONAS DEPURATA. POTASSIUM SEU KALIUM CARBONICUM DEPURATUM. Puzrifed Oarbonate of Potassium. Purified Pearlash. A coarse, granular, white, salt-powder, permanent in dry, deliquescent in moist air; heated in a flame, it communicates to it a violet color. Purified pearlash is soluble in nearly an equal weight of water, forming a strong alkaline solution which frequently appears slightly turbid, and deposits gradually a flocculent or gelatinous sediment of silicic acid; it is soluble in alcohol; its aqueous solution is decomposed by acids with effervescence; it gives a white precipitate with argentic nitrate, and also with magnesium sulphate, and a white granular one with an excess of tartaric acid. Purified pearlash contains about 80 per cent. of potassium carbonate, and not more than 15 to 18 per cent. of water. For Volumetric Estimation, see page 58. Examination: Potassium hydrate is indicated in the solution of the salt, by a grayish or brownish precipitate, instead of a white one, with argentic nitrate; it may be approximately estimated by agitating 100 grains of the dried salt with about half a fluidounce of absolute alcohol; the mixture is then filtered, the residue upon the filter washed with one fluid-drachm of alcohol, and the entire filtrate evaporated to complete dryness in a tared porcelain capsule; the weight of the residue indicates the percentage of potassium hydrate. As an evidence of the absence of carbonate in the residue, one drop of acetic acid may be allowed to fall upon it; effervescence would indicate carbonate. Foreign Salts.-100 grains of the purified potassium carbonate are dissolved in two drachms of water in a test-tube; the solution should be complete and limpid, or nearly so; it is diluted with an equal volume of water, filtered, and over-saturated with hydrochloric acid; a gelatinous precipitate after a time would indicate silicic acid; the liquid is then filtered, and part of the filtrate over-saturated with aqua ammonim; POTASSIUM. 295 a white turbidity would indicate aluminicum salts; the other part of the filtrate is tested with barium chloride for sulp hate. ChUloride and phosphate may be detected in the diluted solution of the salt, over-saturated with nitric acid, by testing it ill two portions, with argentic nitrate for chloride, and by over-saturation with aqua ammonihe, and subsequent addition of ammoniated magnesium sulphate, for phosphate. Sulphite and hyposulphite are detected in the filtered solution of the salt, slightly over-saturated with acetic acid, by adding a, few drops of mucilage of starch, and subsequently two or three drops of diluted solution of iodinized potassium iodide; the first drop of the latter solution should produce a blue reaction at once, which will not occur before the addition of several drops if the above impurities are contained in the salt. Sodium carbonate may be detected by a white, crystalline precipitate, occurring at once or after some time, when a hot diluted solution of the potassium carbonate is nearly neutralized with acetic acid, and subsequently tested with potassium antimoniate. Jietallic impurities are detected in the filtered solution of the salt, by dividing it into two parts, one of which is oversaturated with hydrochloric acid; both are then mixed with twice their volume of hydrosulphuric acid; any immediate reaction in either of the fluids would indicate metals. POTASSII CARBONAS PURA. POTASSIUM SEU KALIUM CARBONICUM PURUM. Pure Carbonate of Potassium. Salt of Tartar. Potassium Carbonate. A white, deliquescent, granular powder, wholly soluble in an equal weight of water, forming a limpid alkaline liquid, which effervesces with acids, and gives a white, crystalline precipitate with an excess of tartaric acid. When exposed to a red heat, dry potassium carbonate loses about 16 per cent. of 296 MANUAL OF CHEMICAL ANALYSIS. its weight. One drachm of the dry carbonate requires for saturation 55.88 grains of citric, and 54.78 grains of tartaric acid. For Volumetric Estimation, see page 58. Examination: Bicarbonrate. -3 drachms of tile carbonate are dissolved in 4 fluid-drachins of water, aided by dipping the test-tube in hot water; the solution should be clear and complete, and remain so after cooling; the separation of a crystalline deposit would indicate potassium bicarbonate. Purified pearlas. —P art of the obtained solution is slightly over-saturated with diluted nitric acid, and allowed to stand in a corked test-tube for several hours; an ensuing gelatinous precipitate would indicate silicic acid; the solution, after filtering, if necessary, is then tested in separate portions, with argentic nitrate for chloricde, and with barium nitrate for sulphate, which impurities would indicate the admixture or substitution of purified pearlash. ]etcas. —Part of the solution is tested with hydrosulphuric FIG. 82. acid in two test-tubes, the one after over-saturation with diluted nitric acid. An ensuing dark coloration or precipitate in either of the fluids would indicate metals. POTASSIUM. 297 Potassium nitrate.-The remainder of the concentrated solution of the salt is over-saturated with diluted sulphuric acid; the clear solution is decanted after a while, and divided into two parts, one of which is mixed with a little ferrous sulphate and then transferred, by means of a pipette, upon concentrated sulphuric acid in a test-tube (Fig. 82); an ensuing purple or brown coloration, at the junction of the two strata of the liquids, would indicate nitrate; the other part is tinged a faint blue with sulphuric-acid solution of indigo, and heated; decoloration would confirm the presence of nitrate. POTASSII CHLORAS. POTASSIUM SEU KALIUM CHLORICUM. Chlorate of Potassium. Potassium Chlo'rate. Colorless, transparent, rhomboidal plates, of a pearly lustre, anhydrous, and permanent in the air, and of a spec. grav. of 2.35; when thrown upon burning charcoal they deflagrate, as they also do more or less violently when triturated or heated with readily-combustible substances, as sulphur, carbon, phosphorus, etc. Potassium chlorate fuses at 334~ C., and afterward gives off oxygen, until at 352~ C. it has parted with the whole of it (39.2 per cent. by weight), leaving behind potassium chloride (60.8 per cent.). When a little sulphuric acid is dropped on the crystals of the chlorate, they become first yellow and then orange-red. Potassium chlorate dissolves in 16.7 parts of water at 15~ C., in about 21 parts of boiling water, and in 120 parts of alcohol of 0.835 spec. grav. Its saturated aqueous solution has a cooling, saline, slightly acerb taste, and, whew mixed with concentrated hydrochloric acid, produces a deep greenish-yellow coloration, with the evolution of chlorine gas. When a few drops of a concentrated solution of potassium chlorate, and subsequently a little concentrated sulphuric acid, are added to a little of a dilute solution of anilin sulphate, upon a watchglass, the mixture assumes a brilliant deep-violet color. With 298 MANUAL OF CHEMICAL ANALYSIS. solution of tartaric acid, the concentrated solution of potassium chlorate gives a white granular precipitate. Examination: Potassium Nitrate.-A little of the powdered salt is heated in a porcelain crucible to a full red heat; the residue, when cool, is dissolved in a few drops of water, and the solution tested with turmeric-paper; a brown discoloration of the paper would indicate an admixture of potassium nitrate. As a confirmatory test, a few drops of the solution of the residue may be added to a solution of mercuric chloride; an ensuing red precipitate will confirm the presence of nitrate. Potadssim chloride and sulphate are detected in the aqueous solution, acidulated with a few drops of diluted nitric acid, by the occurrence of a white precipitate, in the case of the former with argentic nitrate, of the latter with barium nitrate. Most commercial potassium chlorate occasions a slight turbidity with argentic nitrate. POTASSII IHYDRAS. POTASSA. POTASSIUM SEU KALIUM HYDRICUM PURUM. KALIUM CAUSTICUM. Pure Caustic Potash. Potassa. Potassium Hydrate. A white, opaque, granular powder, containing, when completely dry, 23 per cent. of water, or, when fused, white, semitransparent plates or cylindrical sticks, of a fibrous fracture, containing 16 per cent. of water of hydration; exposed to the air, the salt absorbs water and carbonic acid, and gradually deliquesces. It imparts a red color to the flame. Potassium hydrate dissolves in less than its own weight of water, and also in alcohol, with the evolution of heat, and is slightly soluble in ether; its solution has a soapy feel, a burning, corrosive taste, and a strong alkaline reaction; it gives a grayish-brown precipitate with argentic nitrate, soluble in ammonium hydrate, and precipitates from their solutions most POTASSIUM. 299 metallic oxides, several of which are redissolved in an excess of the potassium hydrate; it decomposes ammonium salts with the evolution of ammonia. For Volumetric Estimation, see page 58. Examination: Potassium hydrate must render a clear and complete solution when about 10 grains of it are dissolved in one ounce of alcohol; a residue would indicate foreign salts. Carbonate may be detected when portions of a concentrated aqueous solution of the hydrate are dropped severally into acetic acid and into lime-water; effervescence with the acid, and a white turbidity with the lime-water, would indicate carbonate. Nitrate is indicated by the disappearance of the blue color, on heating a little of the' aqueous solution which has been mixed with an excess of diluted sulphuric acid, and tinted blue with one drop of sulphuric-acid indigo-solution. Chloride and s3ulphate are detected in the diluted solution, over-saturated with dilute nitric acid, by testing it in separate portions, with argentic nitrate for chloride, and with barium nitrate for sulphate. Aluminirum salts and phosphoric acid may be detected in the diluted solution, by means of aqua ammonie, and after filtering, if a precipitate be formed, by subsequent addition of ammoniated magnesium sulphate; a white, gelatinous precipitate with the ammonium hydiate would indicate aluminium salts, and a white, crystalline one with the latter reagent, occurring at once or after several hours, phosphoric acid. Jletals are detected by a dark coloration or turbidity of the solution, when mixed with an excess of hydrosulphuric acid, and subsequently over-saturated with an acid. POTASSII HYDRAS CRUDA. POTASSIUM SEU KALIUMI HYDRICUM CRUDUM. crude Potash. Fused, heavy, compact masses, of a stony appearance, fracture, and hardness, of a soapy feel, burning, corrosive taste, and 300 MANTUAL OF CHEMICAL ANALYSIS. a destructive action on vegetable and animal matters; its color is mostly greenish or brownish gray; it is deliquescent, and rapidly absorbs water and carbonic acid. Heated to redness, it fuses, but remains unchanged; at a very high heat it is volatile. Crude potash dissolves, for the most part, in water and in alcohol, with evolution of heat, leaving a more or less considerable residue of impurities; the decanted solution gives a grayish-brown precipitate with argentic nitrate, soluble upon addition of aqua ammonioe. The insoluble impurities of crude potash consist chiefly of carbonates, sulphates, silicates, chlorides, and ferric and manganic oxides. Examination: In order to ascertain the nature of the impurities, one ounce of the crude potash is triturated and dissolved in two ounces of tepid water, and the whole is allowed to subside in a conical glass measure; two ounces of the clear solution are then mixed with four ounces of strong alcohol, and the mixture allowed to stand for several hours; the solution is then decanted friom the precipitate, as far as practicable, and the latter dissolved in hot water; when cool, this solution is filtered, and the insoluble residue washed with a little water, and preserved upon the filter for further examination. The obtained aqueous solution may be examined as follows: Carbonate and silicate are recognized, on dropping a little of the-solution into a test-tube containing a mixture of equal parts-of water and concentrated nitric acid; the former will be indicated by effervescence, the latter by a white, gelatinous turbidity, ensuing at once-or after some hours. Sulphate and chloride may be detected, in separate portions of the solution, by over-saturating it with nitric acid, and subsequently testing with barium nitrate for sulphate, and with argentic nitrate for chloride. Sulphite and hyposulphite are indicated by the occurrence of an insoluble residue, when a portion of the solution is precipitated with argentic nitrate, and the precipitate is redissolved by ammonium hydrate. Nitrate is detected, in a portion of the solution, after the POTASSIUM. 301 addition of an excess of sulphuric acid and one drop of sulphuric-acid solution of indigo; the blue tint will disappear upon warming, if nitrate be present. Phosphate may be detected by a white, crystalline precipitate, when the solution is mixed with an equal volume of aqua ammonime, and subsequently tested with magnesium sulphate. l.fetallic impurities are recognized by a dark coloration or precipitate, when both the alcoholic solution and the aqueous solution of the residue from the alcoholic one are tested separately with hydrosulphuric acid, and subsequently by over-saturation with hydrochloric acid. The residue left behind from the solution in alcohol, and preserved upon the filter, is washed with a few drops of alcohol, and then dissolved upon the filter in so much diluted hydrochloric acid as to render a neutral solution; this is tested, in separate portions, with ammonium oxalate for ccalcizn, and with barium chloride and a few drops of hydrochloric acid for sulphacte. POTASSII FERROCYANIDUM. POTASSIUM SEU KALIUM FERROCYANATUM. Ferrocyanide of Potassium. Yellow Prussiate of Potassium, Potasszum Ferrocyanide. Large, transparent, yellow, tabular crystals, derived from an octahedron with a square base; they cleave with facility in a direction parallel to the base of the octahedron, have a peculiar toughness and flexibility, contain three molecules (12.76 per cent.) of water of crystallization, and are permanent in the air. When moderately heated, they give off their water of crystallization, and are converted into a white powder, which is decomposed at a red heat, leaving a residue consisting of potassium cyanide, ferric oxide, and carbon. Potassium ferrocyanide is soluble in four parts of cold, and two parts of boiling, water, and insoluble in alcohol; its solution has a mild saline taste, gives a white, granular precipitate with a saturated solution of sodium bitartrate, and, when di 302 MANUAL OF CHEMICAL ANALYSIS. luted, a blue one with ferric, a brick-red one with cupric, and a white one with ferrous and with plumbic salts; it is not acted upon by hydrosulphuric acid, by tannic acid, nor by the alkaline hydrates and carbonates. Examination: Foreign salts are indicated when the potassium ferrocyanide does not yield a complete and clear solution with four parts of water. Carbonate is indicated by effervescence of the concentrated solution upon the admixture of acetic acid, or upon placing fragments of a crystal in diluted sulphuric acid. Sulphate is detected, in the diluted solution, acidulated with nitric acid, by a white turbidity with barium nitrate. C(loride may be detected, when a mixture of 10 grains of the exsiccated salt with 30 grains of fused and powdered ammoniumn nitrate (free of chloride) is gradually introduced into a red-hot iron spoon, and heated to near redness; when cool, the whole is dissolved in water, and the filtered solution over-saturated with nitric acid, and tested with argentie nitrate, which will indicate chloride by a white precipitate. POTASSII IODIDUM. POTASSIUM SEU KALIUM IODATUM. Iodide of Potassium. Potassiurn Iodide. Colorless, anhydrous, semitransparent or opaque crystals, cubical or sometimes elongated in form, permanent in dry, but slightly deliquescent in moist, air, and having a spec. grav. of 2.9. When exposed to heat, potassium iodide decrepitates, and fuses below a red heat; on cooling, it solidifies into a crystalline, pearly mass, without loss of weight, except humidity; at a full red heat, it is slowly volatilized, without decomposition. When a few grains of the salt are heated in concentrated sulphluric acid, or, in a dry test-tube, with a little potassiuml bisulphate, violet-colored vapors of iodine are evolved; and when POTASSIUM. 303 a few grains are dissolved in a little chlorine-water, and this shaken with half its volume of chloroform or carbon bisulphide, these will acquire a purple or violet color. Potassium iodide dissolves in two-thirds of its weight of cold water, in 6- parts of alcohol, of 0.835 spec. grayv., and in 40 parts of absolute alcohol, forming solutions of an acrid, saline taste, and feeble alkaline reaction; the aqueous solution gives, with an excess of tartaric acid, a white, granular precipitate; with argentic nitrate, a yellowish one, which is insoluble in diluted nitric acid, and almost insoluble in ammonium hydrate, but becomes white with the latter; and a vermilion-red precipitate with mercuric chloride, soluble in an excess of either the solution or the reagent; it gives a violet-blue color with a little mucilage of starch, upon subsequent addition of a few drops of chlorine-water (distinction from potassium bromide and chloride), and a white, crystalline precipitate with a saturated solution of sodium bitartrate. Examination: lWater, which may be contained as interstitial moisture in the crystals, is recognized, and may be quantitatively determined, by the loss of weight upon drying a known weight of the triturated salt at about 80~ C. Impurities and Admigxtures.-In order to obtain for examination an average representation of the iodide, several ounces of smaller and larger crystals are selected from the bulk of the salt, and triturated to a granular powder, part of which may serve for the following tests: One drachm of it is dissolved in one fluid-drachim of water; the solution formed imust be clear and complete, and remain so after the addition of 1~ fluidounce of strong or absolute alcohol; an ensuing turbidity or crystalline deposit would indicate foreign salts (carbonate, sulphate, iodate, nitrate); if this precipitate is considerable, it may be collected upon a filter, washed with a few drops of alcohol, and then dissolved in a few drops of warm water; the obtained solution may be tested for carbonate with turmnericpaper, or by allowing one or two drops of it to fall into concentrated hydrochloric acid; a brown coloration of the paper, and effervescence with the acid, will indicate the presence of carbonate; the rest of the solution is acidulated with a few 304: MANUAL OF CHEMICAL ANALYSIS. drops of hydrochloric acid, and tested for sul)7phate with one drop of barium chloride, and subsequently, for nitrate, by tingeing it faintly with sulphuric-acid indigo-solution, anld heating. Another method of ascertaining the presence of foreign salts in potassium iodide, without determining their nature, consists in adding a solution of mercuric chloride to the solution of the iodide, the salts'being taken in the proportion of four equivalents of potassium iodide to one equivalent of mercuric chloride; five grains of tile former are dissolved in three ounces of water in a beaker-glass; a solution of two grains of the latter salt in two ounces of water is then gradually added, with constant stirring, to the solution of the iodide; if this be pure, its excess is just sufficient to redissolve all the mercuric iodide formed; if impure, a deficiency of iodide will give rise to the appearance of a permanent precipitate of mercuric iodide before the whole of the mercuric solution is added, and this result will take place the earlier, the less iodide and the more impurities are contained in the salt. Potassiultm iodacte may be detected in the aqueous solution of the salt, by adding a few drops of mucilage of starch, and then a few drops of a concentrated solution of tartaric acid, insufficient to cause a precipitate; if iodate be contained in the salt, a violet coloration of the liquid will occur at once. Or the aqueous solution, mixed with a few drops of concentrated solution of tartaric acid, may be shaken with some chloroform, which will assume a red color when iodate is present. Iodate may also be recognized in potassium iodide by dropping a crystal of tartaric acid into a strong solution of the iodide in previously boiled, distilled water, and allowing it to remain at rest for several minutes; if iodate be present, the crystal will be enveloped after that time in a yellowish-white zone. Carbonate may be detected by a white turbidity when the aqueous solution of the potassium iodide is mixed with twice its volume of lime-water. Sulphate may be detected in the diluted solution of the iodide, previously acidulated with hydrochloric acid, by a white precipitate with barium chloride. XNitrate may be detected in the aqueous solution, if the salt POTASSIUM. 305 be free from iodate, by adding a little sulphuric-acid mucilage of starch, and by immersing in the liquid a thin piece or rod of bright zinc; if any nitrate be present, the liquid will gradually become blue, the coloration issuing from the zinc. C(hioride and bromide are detected by carefully precipitating, with argentic nitrate, a warm, diluted, aqueous solution of the salt; a slight excess of aqua ammonim is then added, and, after agitation, the mixture is filtered, and the filtrate over-saturated with nitric acid; since ammonium hydrate dissolves only traces of argentic iodide, the transparency of the liquid must be not at all, or only slightly, impaired; a white turbidity, subsiding to a precipitate, would indicate bromide or chloride.* In order to distinguish these, the precipitate is collected upon a filter and washed with a little water, until this ceases to redden blue litmus-paper; the filter is then pierced by a glass rod, and the precipitate rinsed into a test-tube; after subsidence, the water is, as far as possible, decanted, and chlorine water added and agitated with the precipitate; since chlorine decomposes argentic bromide, dissolving the disengaged bromine with a yellow color, bromide will be recognized by a more or less deep yellow coloring of the fluid, while argentic chloride remains unchanged and without any action on chlorine-water. When chloroform or ether is then added to the fluid and agitated, it will absorb the bromine and the yellow color from the water. A confirmatory test for the recognition of bromicle is, to add to a solution of tile salt an excess of solution of cupric sulphate, and subsequently so much of a saturated solution of sulphurous acid as to impart its strong odor to the mixture; the whole is gently warmed, filtered, and heated to boiling, in order to expel the sulphurous acid; when cold, it is re-filtered if necessary, and the filtrate shaken with half its volume of chloroform, which, after subsidence has taken place;will appear yellow if bromide is contained in the salt. * When a comparatively large quantity of potassium iodate is contained in the iodide, argentic iodate is also formed in this test, and gives rise, upon the addition of the nitric acid, to the formation of a white, granular precipitate, which, however, is quite different in appearance from the curdy one of the argentic chloride or bromide. 20 306 MANUAL OF CHEMICAL ANALYSIS. A quantitative estimation of the purity of potassium iodide may be made by completely precipitating with argentic nitrate a warm solution of 10 grains of the salt in about one ounce of' water; after cooling and subsidence, the supernatant menstruum is carefully decanted, so as to avoid any loss of the precipitate; one fluid-drachm of aqua ammonie, diluted with two drachms of water, is then added to the precipitate, and, after agitation for a few minutes, this latter is collected upon a tared, moist filter, is washed with a little water, and dried at a temperature not exceeding 80~ C. If the potassium iodide was pure, 14.1 grains of argentic iodide should be obtained. For Volumetric Estimation, see page 62. POTASSII NIT2RAS. POTASSIUM SEU KALIUM NITRICUM. Nitrate of Potassium. Salpetre..Nitre. Potassium Nitrate. Long, striated, six-sided, prismatic crystals, with dihedral summits, colorless and transparent, and of a spec. grav. of 2.0; or a white, granular powder, permanent in the air. When thrown upon burning coals, it deflagrates with bright scintillations, leaving an alkaline, residue, which, when heated upon the looped end of a platinum wire, imparts a red color to the flame; exposed to heat, it fuses below redness. Potassium nitrate is soluble in water. 100 parts of which dissolve, at 00 C., 13.3 parts, at 18~ C., 29 parts, and at 97~ C., 236 parts of the salt; it is far less soluble in glycerin, and almost insoluble in alcohol; its aqueous solution is neutral, has a cooling, saline taste, and forms a white, granular precipitate with concentrated solution of sodium bitartrate; a few drops of it mixed with a solution of ferrous sulphate, and carefully placed upon concentrated sulplhuric acid (Fig. 82, page 296), give rise to the formation of a dark coloration upon the line of contact between the two fluids. POTASSIUM. 307 Examination: Chloride and sulphlate are detected in the diluted solution of the salt by white precipitates when acidulated with nitric acid, and tested in two separate portions, with argentic nitrate for chloride, and with barium nitrate for sulphate. CEhlorate is indicated by a yellow coloration, and the evolution of chlorine, when a concentrated solution of the potassium nitrate is mixed and gently warmed with an equal volume of concentrated hydrochloric acid. (Calcium and magnesium salts are detected by a white turbidity when the diluted solution is warmed with dilute solution of sodium carbonate; they may be distinguished by adding a little aqua ammonia to the dilute solution of the salt, and testing it, in separate portions, with ammonium oxalate for calcium, and with sodium phosphate for magnesium. Sodium nitrate may be detected by a white, crystalline precipitate, occurring either at once or after several hours, when a concentrated cold solution of the salt is tested with a few drops of solution of potassium antimoniate, and then allowed to stand for six hours. If potassium nitrate contains even a few per cent. of sodium nitrate, it will have a moist appearance, arising from the deliquescent character of the latter salt. POTASSII PERXANGANAS. POTASSIUM SEU KALIUM PERMANGANICUM SEU HYPERMANGANICUM. Permanganate of Potassium. Potassium Permanganate. Slender, prismatic, dark purple crystals, of a metallic lustre, and permanent in the air; they decrepitate when thrown upon burning coals, or when suddenly heated, and detonate with a flame when triturated with equal parts of sulphur, and heated to 1770 C. Potassium permanganate is soluble in 16 parts of cold, and 2 parts of boiling, water, forming a deep purple solution, which, when highly diluted, is lilac-colored; it is insoluble in alcohol 308 MANUAL OF CHEMICAL ANALYSIS. and in chloroform; its solution has a sweet, astringent taste, is neutral, and becomes yellowish brown when mixed and heated with alcohol. Since permanganic acid is readily reduced, the solution of the salt is decomposed and decolorized by most organic substances, and by inorganic reducing agents-e. g., sulphurous, hydrosulphuric, and oxalic acids, and all metallic subsalts. Potassium permanganate is, therefore, a powerful oxidizer, causing more or less violent reactions with many substances, and the combustion of inflammable bodies. POTASSII ET SODII TARTRAS. POTASSIUM ET SODIUM TARTARICUM. NATRIO-KALIUMI TARTARICUM. SODIUM TARTARATUM. TARTARUS NATRONATUS. Rochelle Salt. Seignette Salt. Potassium and Sodium Tartrate. Large, colorless,, transparent, prismnatic crystals, the faces of which are unequally developed, containing eight molecules (29.86 per cent.) of water of crystallization, and being slightly efflorescent. The salt occurs in commerce generally ground, as a snow-white powder. When heated in a porcelain capsule, it undergoes aqueous fusion, the water evaporates, and the salt is decomposed, with the evolution of inflammable vapors and the odor of caramel, while a black residue is left, which consists of a mixture of potassium and sodium carbonates with carbon, and which colors turmeric-paper brown, and imparts a yellow color to the flame when heated upon the looped end of a platinum wire. Potassium and sodium tartrate is insoluble in alcohol, but soluble in 2 to 21 parts of cold, and in less than its own weight of boiling, water; the solution is neutral, las a mild, cooling, saline taste, and forms a white, granular precipitate with acids and with solutions of acidulous salts. For Volumetric Estimation, see page 58. Examination: Two drachms of the salt are dissolved in six-drachms of warm water; the solution should be clear and complete, and remain POTASSIUM. 309 so after cooling; it should not act upon litmus-paper, nor effervesce upon addition of hydrochloric acid (evidence of the absence of sodium carbonate or bicarbonate). CLlorides and sulphates may be detected by a white precipitate when the diluted solution of the salt, acidulated with nitric acid, is tested in two separate portions, with argentic nitrate for the former, and with barium nitrate for the latter: In case the solution separates granular potassium bitartrate upon the addition of the acid, sufficient hot water is added to redissolve the precipitate before adding the reagent. Calcium salts are detected in the diluted solution, by means of ammonium oxalate. lfetallic impurities are detected in the concentrated solution b)y hydrosulphuric acid, and subsequent addition of a little aqua ammonim. Crystallized potassium and sodium tartrate, being in appearance somewhat similar to crystallized borax and alum, and therefore liable to incidental mistake, may readily be distinguished from either of these substances, in addition to its physical characters, by its taste, by its neutral reaction-alum being sour, borax alkaline, and by the black alkaline fuse upon incineration, while both borax and alum swell up to a porous mass, and yield a white or colorless fuse. POTASSII SULPHAS. POTASSIUM SEU KALIUM SULPHIURICUM. Sulphate of Potassium. Potassium Sulphate. Hard, colorless, transparent, short, six-sided prisms, terminated by six-sided pyramids, or a white, granular powder, anhydrous, and permanent in the air, and having a spec. grav. of 2.66; when heated, the crystals decrepitate strongly; the'salt imparts a purple color to the flame. Potassium sulphate is soluble in about 12 parts of cold, and 4 parts of boiling, water, but insoluble in alcohol; the solution lhas a saline bitter taste, is neutral, and forms white precipitates 310 MANUAL OF CHEMICAL ANALYSIS. with tartaric acid or sodium bitartrate, and with solutions of salts of calcium, barium, or lead. Examination: Metallic imrpurities are detected in the warm aqueous solution, by a dark coloration or turbidity, with an excess of hydrosulphuric acid. and subsequent acidulation with hydrochloric acid. Potassium ferrocyanide should cause neither a blue (iron) nor a reddish (copper) reaction in the slightly acidulated solution. Sodium sulphalte is indicated by a greater degree of solubility in cold water than that above stated; one drachm of the powdered salt, when dissolved in one fluidounce of boiling water, must, on cooling, give a crystalline deposit; otherwise sodium sulphate, or the admixture of more soluble salts, is indicated; in this case the diluted solution may be acidulated with nitric acid, and tested by means of argentic nitrate for chloride. POTASSII SULPHURETUMX. POTASSII SULPHIDUM. POTASSIUM SEU KALIUM SULPHURATUM. HEPAR SULPHURIS. Sulphuret of Potassium. Potassium Sulphide. Solid, fused fragments, of a yellowish-brown color, when freshly prepared or recently broken; on exposure to the air they assume a greenish appearance, and finally become of a dirty white, in consequence of gradual decomposition by the action of atmospheric moisture and oxygen, the sulphides being successively converted, with the evolution of hydrogen sulphide, into hyposulphite, sulphite, and tltimately sulphate. When moistened with acids, potassium sulphide evolves hydrogen sulphide. Potassium sulphide, which is usually a variable mixture of higher potassium sulphides with hyposulphite, sulphite, and sulphate, and with undecomposed carbonate, dissolves in 3 to 4 parts of water, and also in alcohol, leaving behind in the POTASSIUM. 311 latter case the oxygen salts; these solutions have an orangeyellow color, a nauseous, alkaline, bitter taste, and the odor of hydrogulphuric acid, which is abundantly evolved, with the separation of sulphur, upon the addition of acids; they.precipitate metallic sulphides from the solutions of most of the metallic salts. POTASSII TARTRAS. POTASSIUM SEU KALIUM TARTARICUM. Tartrate of Potassium. Potassium Tartrate. Colorless, semi-transparent, irregular, six-sided prisms, with dihedral summits, or a. white, granular powder, slightly deliquescent. When heated in a dry test-tube, potassium tartrate melts, swells up, and is decomposed with the evolution of empyreumatic vapors, leaving behind a mixture of carbon and potassium carbonate, which effervesces with acids, and imparts a red color to the flame. Potassium tartrate is soluble in a little less than its own weight of cold, and in half its weight of boiling, water, yielding a neutral solution, of a mild saline taste; it is but sparingly soluble in alcohol; its aqueous solution is decomposed by most acids and acidulous salts, forming, if not too dilute, a white, granular deposit of bitartrate. For Vol7umetric Estimation, see page 58. Examination: Potassium and Sodium Tartrate.-One drachm of the salt is shaken with 1l~ drachm of cold water; a clear and complete solution must take place, an incomplete solution may indicate an admixture of Rochelle salts. This may be ascertained by reducing about one drachm of the potassium tartrate, by ignition in a porcelain crucible, to carbonate, and then testing the filtered solution of the residue by mixing it with an equal volume of solution of potassium antimoniate, the occurrence of a white, crystalline deposit, at once or after several hours' stand 312 MANUAL OF CHEMICAL ANALYSIS. ing, would prove an adulteration with potassium and sodium tartrate. Bicarbonate, carbonate, and bitartrate, are recognized in the solution of the salt, the two former by a white precipitate with calcium chloride in the cold, and by an alkaline reaction upon turmeric-paper; the last by an acid reaction upon blue litmuspaper. Sulp2hate and chloride may be detected in the dilute solution of the salt, when it is slightly acidulated with diluted nitric acid, and then tested, in separate portions, with argentic nitrate for chloride, and with barium nitrate for sulphate. MJ'etallic izmpur'ties are recognized by mixing a concentrated solution of the salt with two or three times its volume of hydrosulphuric acid, and by subsequent acidulation with acetic acid. Should a white, granular deposit of potassium bitartrate occur, the liquid is diluted with boiling water, or is warmed so as to redissolve the precipitate. Any reaction with the hydrosulphuric acid, before or after acidulation, would indicate metallic impurities. QUINIA. CHININUM. CHINIUM. Quinine. Quinia. A white, granular powder, or small, needle-like crystals, containing 14.28 per cent. of water of crystallization; permanent in the air; when heated, quinia fuses at about 196~ C., and upon cooling solidifies into a resin-like mass, yellow, translucent, and friable; at a higher temperature it is wholly dissipated. Quinia dissolves in about 1,200 parts of cold, and 250 parts of boiling, water, and in about 2 parts of boiling alcohol, and in 60 parts of ether; * it is also soluble in chloroform, and in benzol; its solutions have a bitter taste, and a feeble alkaline * The solubility of quinia in ether differs according to the form of the alkaloid: it, requires about 60 parts when in the crystallized state, but only about half that quantity when it is amorphous; for instance, when one grain of quinia sulphate QUINIA. 313 reaction, and neutralize acids. Quinia is freely soluble in diluted acids; these solutions exhibit an azure-blue fluorescence, caused by a change of the refrangibility of the invisible chemical rays. Concentrated sulphuric and nitric acids dissolve quinia without color. Solutions of qtinia and its salts are precipitated by the alkaline hydrates, carbonates, and bicarbonates, by calcium hydrate, by tannic and picric acid, by potassium ferrocyanide, and by potassio-mercuric iodide. The precipitates with calcium, potassium, sodiumn, and amml-onium hydrates, are redissolved by a great excess of the precipitant. Solutions of quinia and its salts render an emerald-green solution when dissolved in, or mixed with, chlorine-water, and afterward with an excess of aqua ammonie; the green color passes into purple upon the subsequent addition of potassium ferrocyanide; this characteristic reaction is most strikingly exhibited when, to the solution of quinia in cl)lorine-water, the solution of potassium ferrocyanide is first added, and subsequently the aqua ammonia. When a solution of quinia or its salts in acidulated water is precipitated with ammonium hydrate, and the turbid mixture is then divided into three portions in as many test-tubes, and these shaken severally with a little ether, chloroform, and benzol, the precipitate will be dissolved, and the liquids subside into two clear, colorless strata in each test-tube. Estimation of the Alkaloids in Cinchona-Barks: The therapeutical value of the cinchona-barks is due to the alkaloids contained in the bark, and of which the principal ones are quifnia, quinidia, cinchonia, and cinchonidia. The estiTmation of the commercial value, therefore, depends upon the determination of the quantity of these alkaloids, and in particular of the first one, in a known weight of the bark; and, from among the numerous methods employed for this purpose, the following ones are simple and expeditious: is dissolved in about 15 drops of acidulated water, and subsequently precipitated with aqua ammonie, 10 grains of ether suffice to redissolve the alkaloid; while at least 35 grains of ether will be required for solution, when the precipitate is allowed to stand for 24 hours, and become crystalline, previous to the addition of the ether. 314 MANUAL OF CHEMICAL ANALYSIS. I. From a large number of pieces of the bark, small fragments are cut and reduced to a fine powder, so as to represent as nearly as possible the average of the bark to be examined; 10 drachms of the powder are mixed with an equal bulk of coarsely-powdered quartz or glass, and the mixture introduced into a comparatively narrow glass percolator, whose lower end is drawn into a point, and loosely closed with some cotton; the powder is covered with a layer of glass or quartz, and, when the percolator is placed in a perpendicular position, water, acidulated with about one per cent. of concentrated sulphuric acid, is introduced until it has penetrated the column and commences to drop out, then the upper orifice is corked, and the whole allowed to stand for several hours, when the cork is removed, and the percolation with the acidulated water is continued, until a few drops of the menstruum, received in a test-tube, cease to have a bitter taste, or to become turbid on addition of aqua ammlonise. When this point is reached, and the bark completely exhausted, the entire liquid is poured into a porcelain dish, and three drachms of powdered, calcined marble are added, and the mixture evaporated to dryness on a water-bath. The dry residue is triturated, and introduced into a flask, and repeatedly and completely extracted with strong alcohol. The filtered alcoholic solution is evaporated in a small, tared beakerglass at a gentle heat, and, when dry, the beaker is allowed to stand for several hours at a temperature-near 80~ C.; it is finally weighed. and, when the tare is subtracted, the difference answers approximately to the quantity of cinchona alkaloids contained in the 10 drachms of the bark. When a quantitative determination of the quinia, quinidia, and cinchonia is desired, the alkaloids contained in the beaker are exhausted with ether, which dissolves the two former, and leaves the latter behind. The ethereal solution is then mixed with a little alcohol, acidulated with hydrochloric acid, and completely precipitated with platinic chloride; the ensuing precipitate of quinia- and quinidia-platinic chloride is collected upon a double filter, both of the same paper and size, is washed with alcohol, dried at 80~ C., and then weighed; the second filter serving as the tare of the one containing the precipitate. The weight of the platinic precipitate is divided by QUINIA. 315 2.274, and the quotient gives the quantity of quinia and quinidia contained in 10 drachms of the cinchona-bark. The residue remaining undissolved in ether is dissolved in some alcohol, one drop of hydrochloric acid is added, and it is then completely precipitated with platinic chloride; the precipitate of cinchonia-platinic chloride is washed upon a double filter with'alcohol, is dried at 80~ C., and weighed as the preceding one. The weight is divided by 2.34, the quotient gives. the quantity of the cinchonia contained in 10 drachms of the cinchona-bark.' The platinum may be recovered by igniting the precipitates in an open crucible of platinum or porcelain. II. The British Pharmacopoeia gives the following process for the estimation of the quiniia in cinchona-barks: " Boil 100 grains of the bark, reduced to a fine powder, for a quarter of an hour in a fluidounce of distilled water, acidulated with 10 drops of hydrochloric acid, and allow it to maccerate for 24 hours. Transfer the whole to a small percolator, and, after the fluid has ceased to drop, add at intervals about an ounce and a half of similarly acidulated water, or until the fluid which passes through is free from color. Add to the percolated fluid, solution of plumbic subacetate, until nearly the whole of the coloring-matter has been removed, taking care that the fluid remains acid in reaction. Filter, and wash with a little distilled water. To the filtrate add about 35 grains of potassium hydrate, or as much as will cause the precipitate, which is at first formed, to be nearly redissolved, and afterward 6 fluid-drachms of ether. Then shake briskly, and, having removed the ether, repeat the process twice with 3 fluiddrachms of ether, or until a drop of the ether employed leaves, on evaporation, scarcely any perceptible residue. Lastly, evaporate the mixed ethereal solutions in a capsule. The residue, which consists of nearly pure quinia, when dry, should weigh not less than two grains (2 per cent.), and should be readily soluble in diluted sulphuric acid." III. Another method * is the following: * This method, suggested by P. Carles, in 1869, differs from similar ones mainly by the employment of chloroform for exhaustion, instead of ethylic or amylic alcohol, of ether, or of benzol, and by the separation of the quinia sulphate from a solu 316 MANUAL OF CHEMICAL ANALYSIS. One thousand grains of a good average sample of the powdered and dried bark are intimately mixed with from 300 to 4:00 grains of slacked lime, mixed with about. 1,750 grains of water, and the pasty mixture of the bark and lime dried at a gentle heat; the cakes thus formed are reduced to a coarse powder, and pressed into a small percolator, with stop-cock and glass stopper; chloroform is then gradually poured on the contents until they are moistened throughout; stop-cock and glass stopper being closed, the whole is allowed to stand for 12 hours, when the bark is completely exhausted by successive slow percolation with chloroform. About 7,000 grains of chloroform will be required for the exhaustion of the bark, which may be ascertained by evaporating a few drops of the last percolate upon a watch-glass, and by dissolving the residue with a few drops of chlorine-water and one drop of diluted hydrochloric acid, and by adding the solution to a little aqua amrnmoniae in a small test-tube. The bark is exhausted when the occurrence of a greenish coloration with this test ceases. When this is the case, the chloroform is displaced by water poured upon the percolator, and, as soon as chloroform ceases to drop off, the entire percolate is evaporated upon a water-bath, until a dry residue is left. If desired to save the chloroform, especially when the test is performed on a larger scale, it may be distilled off in a smallretort with a Liebig cooler, from a water-bath: the distillation should not, however, be carried on to dryness, but the remainder of the fluid is to be evaporated to dryness in a porcelain capsule. The residue consists of the alkaloids mixed with about their own weight of resinous and such other matters of the bark as are soluble in chloroform; it is treated several times with so much cold diluted sulphuric acid (1 part concentrated acid to 10 parts of water) as is required for solution of the alkaloids; about 500 to 600 fluid-grains of the diluted acid will be sufficient. The solution is passed through a small filter, previously moistened, and this is washed with a little cold water; the colorless filtrate is heated in a flask to near boiling, and, when tion of ammonium sulphate, wherein it is said to be insoluble. It has the advantage of being simple in operation, and of occasioning the least loss, and giving the fullest yield of quinia, with an almost complete exclusion of cinchonia. QUINIA. 317 hot, so much aqua ainmonioe is added as nearly to neutralize the acid solution. This is then allowed to cool slowly. As quinia sulphate is insoluble in solution of ammoniumn sulphate, all the quinia sulphate will deposit in a crystalline crust, together, probably, with a part of the quinidia sulphate; the menstruum is then poured off into another beaker, and the crystalline mass broken and washed with a few drops of cold water, either in the beaker or upon a tared filter, after which it is dried at about 80~ C. If the mother-liquor is found to be very acid, it has to be neutralized with aqua ammonia, and once more allowed to stand and cool for crystallization; if this has taken place, the crystals are collected upon a tared filter, washed with cold water, and also dried. The entire yield of dried crystals is then weighed, and the number of grains, after having added 11 per cent. to make up *for the water of crystallization, contained in quinia sulphate, and lost on drying, when divided by 10, gives at once the percentage of quinia sulphate obtainable from the cincholla-bark. IV. An adequate and perhaps the most reliable method for the estimation of the value of conmmercial cinchona-bark, designed for the manufacture of Quinie Sulphas, is the preparation of quinia sulphate on a small scale by the process of the U. S. Pharmacopceia: Twelve ounces of the bark, in coarse powder, are thoroughly mixed with 4 pints of water and half an ounce of hydrochloric acid of 1.160 spec. grav.; the mixture is allowed to macerate for twelve hours, and is then gently boiled in a porcelain capsule for about one hour; it is then strained through muslin, and the residue is boiled twice successively, with half of a mixture consisting of 3 pints of water and 3 drachms of hydrochloric acid, and strained; the powder is finally submitted in the muslin to a gentle pressure, and this is repeated again after it has been moistened with about 6 ounces of boiling water. The obtained liquids are mixed in a porcelain capsule, and heated; now, while hot, a mixture of 10 drachms of lime, previously slacked with 8 ounces of water, is gradually added, with constant stirring with a glass rod, until the solution of the lime, and the corresponding formation of a precipitate of quinia, cease, or 318 MANUAL OF CHEMICAL ANALYSIS. until the liquid turns turmeric-paper brown. The precipitate is collected upon a filter, and washed with distilled water, until this ceases to cause a turbidity, when a few drops are allowed to fall into a solution of argentic nitrate, acidulated with nitric acid; the precipitate is then dried, and, when detached from the filter, reduced to a fine powder, which is successively exhausted with decreasing quantities of boiling alcohol, separating the alcohol from the precipitate by decantation, which operation is repeated until the alcohol is no longer rendered bitter. The obtained alcoholic solutions are mixed, and are concentrated to a syrupy consistence, either by evaporation or by distillation; the remainder is then transferred and rinsed into a flask, with 12 ounces of boiling water; it is then heated to boiling, and so much diluted sulphuric acid is added as just completely to dissolve the quinia. Then half an ounce of common animal charcoal is added, or so much as to leave the liquid of a faintly acid reaction upon blue litmus-paper; after a few minutes' gentle stirring, the mixture is filtered while hot, and the residue washed on the filter with a little boiling water; the entire filtrate is then set aside to crystallize. The crystals are separated from the liquid, which is allowed to dlop off as much as possible, and they are then dried in a porcelain capsule, covered with bibulous paper, at a heat not exceeding 50~ C., taking care to avoid the efflorescence of the dry crystals. The remaining liquid is evaporated at a boiling heat to nearly two-thirds of its volume, and is then allowed to crystallize again. These crystals are separated and dried as before. The mother-water may be made to yield an additional quantity of quinia sulphate by precipitating the quinia with aqua ammonihe, and treating the precipitated alkaloid as before with proportionate quantities of distilled water, sulphuric acid, and animal charcoal. The entire yield of quinia sulphate, when dry, represents the available quantity of the salt obtained from 12 ounces of the bark, which number has to be multiplied by 8.33 in order to express the percentage value of the bark in quinia sulphate. QUINIA. 319 QUINIUE HYDROCHLORAS. QUINLE MURIAS. CHININUM SEU CHINIUM HYDROCHLORICUM SEU HYDROCHLORATUM. Hydrochlorate of Quinia or Quinine. Quinia Hydrochloride. White, silky needles, or a crystalline powder; when exposed to heat, the salt fuses, and finally burns away without residue. Quinia hydrochloride is soluble in about 20 parts of cold water, in from two to three parts of alcohol, and only slightly in ether; but it is freely soluble in acidulated water, and in diluted as well as in concentrated acids, without change of color; its solutions are neutral, have a bitter taste, and yield an emerald-green coloration with chlorine-water, on subsequent addition of an excess of aqua ammonia; the green becomes purple with potassium ferrocyanide; the aqueous solution, acidulated with nitric acid, yields a white, curdy precipitate with argentic nitrate, soluble in an excess of ammonium hydrate, and a white precipitate with aqua ammonioe, which, however, is dissolved by ether, alcohol, chloroform, or benzol, when added and agitated with the liquid. The examination of quinia hydrochloride for quality and purity is the same as that of quinia sulphate, as described on pages 321-324. In reference to the mode of its preparation, its aqueous solution needs, moreover, to be examined for contamination with quinia sulphate and with barium chloride, by acidulation with nitric acid, and subsequent testing in separate portions with baritim nitrate for the former, and with diluted sulphuric acid for the latter. Either of these impurities, of course, excludes the presence of the other one, without impairing the solubility of the salt. In the application of the chemico-microscopic test (page 323), the concentrated aqueous solution of the quinia hydrochloride may be added to the solution of potassium sulphocyanide without the addition of acid. 320 MANUAL OF CHEMICAL ANALYSIS. QUININE SULPHAS. CHININUM SEU CHINIUM SULPHURICUM. Sulphate of Quinia or Quinine. Quinia Sulphate. Fine, silky, slightly flexible, snow-white needles, interlaced among one another, or grouped in small, starlike tufts; the crystals contain seven molecules of water of crystallization, five of which (about 11 per cent. by weight) evaporate, with a slight efflorescence of the salt, when exposed to a warm and dry air; the remaining two molecules separate at about 116~ C., the fusing-point of quinia sulphate, when it still retains one molecule of water of constitution; at a stronger heat, the fused salt assumes a deep red color, and finally, when heated in the open air, burns slowly and wholly away. Quinia sulphate is but sparingly soluble in cold water, one part requiring 790 parts of cold, and 33 parts of boiling, water; it dissolves in 60 parts of alcohol, and is also soluble in benzol, but only sparingly in ether and in chloroform. Dilute as well as strong acids will dissolve it freely, forming colorless, bitter solutions, which, when diluted, exhibit a blue fluorescence. Solutions of quinia sulphate are precipitated by the alkaline hydrates, carbonates, and bicarbonates, by lime-water, by tannic and picric acids, by potassium ferrocyanide, and by potassio-mrercuric iodide. The precipitates with calcium hydrate and With the alkaline hydrates are soluble in an abundance of the precipitant. Like all quinia salts, quinia sulphate renders.an emeraldgreen reaction when dissolved in, or when its solution is mixed with, chlorine-water, and afterward with an excess of aqua ammonise; the green color passes into purple upon the subsequent addition of a few drops of solution of potassium ferrocyanide, which reaction is especially striking when, to the solution of the quinia sulphate in water, the solution of potassium ferrocyanide is first added, and subsequently the aqua ammoniue. One hundred grains of quinia sulphate, dissolved in water acidulated with hydrochloric acid, yield, upon complete precipi QUINIA. 321 tation with barium chloride, a precipitate of barium sulphate, which, when collected, washed, and dried upon a filter, and completely incinerated by ignition, should weigh 26.6 grains. Examination:.Mineral admixtures are detected by a residue left after igniting a little of the salt upon platinum-foil, or after dissolving about five grains of the salt in four drachms of boiling alcohol. Ammonziwtm salts are recognized by the odor of ammonia, and by the formation of white vapors fiom a glass rod moistened with acetic acid, when held in the orifice of the small test-tube, wherein a few grains of the quinia sulphate are heated with strong solution of potassium hydrate. (Chlorides and hydrochiorides may be recognized in the dilute solution of the salt in water, acidulated with nitric acid, by a white, curdy precipitate with argentic nitrate. Stearic acid may be detected in the above-described alcoholic solution, by adding an equal volume of water; the liquid becomes turbid, but, on warming it gently, by dipping the testtube in hot water, it becomes transparent again; the appearance of an oily layer on the surface would indicate the above fatty acid. SaliciLn, sugar, and mannite, may be detected in the solution of the preceding test, if free from fatty substances, by mixing it, in a porcelain capsule, with about five grains of barium carbonate, and evaporating the whole to dryness with constant stirring; the residue is triturated with a little water, and transferred upon a moist filter; the obtained filtrate is evaporated at a gentle heat, upon a watch-glass, and must leave no residue, or only a very small one; if a residue remains, it is divided, and placed upon two IG. 8. watch-glasses, with one drop of water upon each, and is again dried up at a gentle heat; then, upon the one glass, a small drop of concentrated sulphuric acid 21 322 MANUAL OF CHEMICAL ANALYSIS. is allowed to fall from a glass rod or from a small pipette (Fig. 83); a red color will be produced if salicin is present, a black one if sugar; mannite remains unchanged, and may be detected on the second watch-glass, by a few drops of' alcohol, which dissolve the mannite, and leave it behind in small, acicular crystals upon spontaneous evaporation. Since quinia sulphate dissolves without apparent change in strong sulphuric acid, even when gently warmed, this test may be directly applied for the detection of admixtures of sugar, mannite, or fatty acids, which will produce a black coloration; a red coloration might be indicative of the presence of salicin, but, since many other compounds produce a similar reaction, the following additional test may be employed for salicin: Four grains of the quinia sulphate are dissolved, in a testtube, in one drachm of water and four drops of concentrated hydrochloric acid; the solution is boiled for a few minutes, when, if salicin be present, a white turbidity caused by the formation of saliretin will take place. Cinchonia, Cindhonidia, and Q uinidia.-These associate alkaloids of quinia are distinguished from the latter, and from each other, by the difference in their solubility in aqua ammoniae and in ether. When freshly precipitated, quinidia requires for re-solution from 10 to 11 times as much aqua ammonime as an equal quantity of quinia; cinchonidia from 12 to 13 times as much; while cinchonia is not dissolved by a much larger proportion than is required by either of the other alkaloids, and, though, when mixed, in a very small proportion, with quinia, it is dissolved at first, it afterward separates on standing. With regard to their solubility in ether, the alkaloids differ as follows: Thirty grains of quinia sulphate, when precipitated with sodium carbonate, yield about 22 grains of alkaloid, which, if all quinia, would require for solution about four fluidounces of ether; if all quinidia, about six fluidounces; if all cinchonidia, about 10 fluidounces; and, if all cinchonia, about 40 fluidounces of ether. Hereupon the three following tests are based: 1. Thirty and two-thirds grains (two grammes) of tile quinia sulphate are mixed and agitated with five fluid-drachms (20 QUINIA. 323 cubic centimetres) of distilled water, at a temperature below 15~ C., and the mixture allowed to stand for half an hour, at a temperature not exceeding 15~ C.; it is then filtered, and 1I fluid-drachm (five cubic centimetres) of the filtrate are placed in a long, narrow test-tube, and 1- fluid-drachm (seven cubic centimetres) of aqua ammonite added, taking care that the two fluids do not mix; the tube is then closed, with the finger or a cork, and gently reversed, without undue agitation, when the liquid should, after a while, become clear and transparent. Otherwise an unusual quantity of the above alkaloids is indicated. 2. Ten grains of the quinia sulphate are agitated, in a narrow test-tube, with a mixture consisting of one drachm by weight of pure ether and 10 drops of aqua ammonim, and are then allowed to rest; the liquid should, after a while, form two separate, colorless, and transparent layers, without any white or crystalline matter floating at the line of contact between the two strata; such an appearance would also indicate the presence of the above associate alkaloids of quinia. 3. Ten grains of the quinia sulphate are dissolved, in a test-tube, in one fluid-drachm of distilled water, and 10 drops or less of diluted sulphuric acid; then 2~ fluid-drachms of ether, 3 drops of alcohol, and 40 drops of a solution of potassium hydrate (1 part to 12 parts of water) are added; the testtube is corked, agitated, and allowed to stand for 12 hours. When pure, the two fluid strata, and the line of their contact, will be clear and transparent; but, if even traces of cinchonia and cinchonidia are present, they will be seen floating as a white cloud at the line of separation between the two strata; when einchonidia is the only impurity, it will appear at the line of contact as an oily-like stratum, consisting, when magnified, of minute amorphous particles, while cinchonia appears crystalline. Another and ready method of.distinguishing the three principal associate alkaloids, in quinia sulphate, is Stodcdard's chemtico-microscopic test. Five grains of the quinia sulphate are dissolved in two drachms of distilled water, acidulated with four drops of diluted sulphuric acid; of this solution, one small drop is placed upon the glass slip, and about half a drop of so 324 MANUAL OF CHEMICAL ANALYSIS. lution of potassium sulphocyanide is put by its side; both are then covered with one piece of thin glass, which will cause the drops to touch. At the line of junction, an immediate precipitation takes place, and the crystals of the different alkaloids may be recognized, under the microscope, at a magnifying FIG. 84. FrIG. 85. FIG. 86. 400 diam. 400 diam. 400 diam. Quinia Quinidia Cinchonia Sulphocyanide. Sulphocyanide. Sulphocyanide. power of about 60 diameters. The particles arrange themselves into groups, quinia salt forming long, slender needles (Fig. 84), quinidia, radiate crystalline needles (Fig. 85), and cinchonia, comparatively large prisms (Fig. 86). QUINIME TANNAS. CHININUM SEU CHINIUM TANNICUM. Tannate of Quinia or Quinine. Quinia Tannate. A yellowish-white, amorphous powder, Whichl, when heated, becomes brown, fuses, and is wholly dissipated; it is only sparingly soluble in cold water, requiring 4M3 parts of it, but dissolves in 21 parts of boiling water; addition of acids increases the solubility to some extent; it is also soluble in alcohol; its aqueous solution has an astringent, bitter taste, and a feebly acid reaction; it is precipitated by metallic salts, and becomes black upon the addition of a few drops of solution of ferric chloride. When 10 grains of quinia tannate are mixed with QUINIA. 325 10 grains of zinc oxide and a little water, and the mixture allowed to stand for several hours, in a warm place, then agitated with about two fluid-drachms of alcohol, and after a while filtered, and the filtrate evaporated to dryness, at a gentle heat, in a beaker-glass, a residue is obtained, which, when dissolved in a little chlorine-water, forms a solution which renders the characteristic emerald-green reactions of quinia with aqua ammonite, passing to purple upon addition of potassium ferrocyanide. Examination: Admixtures of tannic or gallic acid, s6ugar, mannite, or dextrinm, may be recognized by their ready solubility in cold water in comparison with that of quinia tannate. Starch is detected by a blue color, when one drop of iodinized solution of potassium iodide is added to a little of the quinia tannate shaken with some boiling water. QUINIME VALERIANAS. CHININUM SEU' CHINIUM VALERIANICUM. Valerianate of Quinia or Quinine. Quiniac Valerianate. Colorless, rhomboidal plates, of a pearly lustre and a faint odor of valerianic acid, permanent in the air; they fuse at a low temperature, and are entirely dissipated at a stronger heat, emitting white, inflammable vapors. Quinia valerianate is soluble in six parts of cold, and' one part of boiling, alcohol, in 110 parts of cold, and 40 parts of boiling, water, but only sparingly in ether; diluted acids dissolve it freely, and strong sulphuric acid does so without color, if heat is not applied; it is also soluble in chlorine-water, forming a solution which renders the emerald-green reaction of quinia with ammonium hydrate. Examination: Stearic acid, sugar, and salicin, are detected by agitating some of the quinia valerianate with strong sulphuric acid, in a 326 MANUAL OF CHEMICAL ANALYSIS. test-tube; a black coloration would indicate one or both of the two former; a red one, salicin. In the case of a black reaction, a special test for salicin has to be made; a little of the valerianate is agitated with cold water, the filtrate is then evaporated at a gentle heat, to a small bulk, and this is strongly acidulated with a few drops of concentrated hydrochloric acid, and heated; a white turbidity, taking place after a while, would indicate salicin. Quinia hydrochloride and sulspate may be detected, in the filtered aqueous solution of the salt, acidulated with a few drops of nitric acid, by testing portions of it with argentic nitrate for the former, and with barium nitrate for the latter. They will be indicated by a white precipitate with the respective reagent. Zinc VFalerianate or.Acetate.-The absence of these or any other mineral salts, not readily volatilizable, may be ascertained by exposing the salt to a red heat, upon platinumn-foil, whereby the organic matter is completely dissipated, leaving metallic oxides or carbonates behind, if any be present; if a residue remains which appears straw-yellow while hot and white when cold, it may be examined for zinc oxide by scraping it off carefully, and dissolving it, in a test-tube, in a few drops of diluted nitric acid; the solution is then mixed with twice its bulk of hydrosulphuric acid; if a precipitate is formed, it is collected upon a filter, and examined for the first group of metallic oxides by the method described on pages 39 and 41; the filtrate is over-saturated with ammonium hydrate; a white precipitate, soluble in liquor potassee, would confirm the presence of zino oxide. QUINOIDINUM. CHINOIDINUM. Quinoidine. A brittle, resin-like mass, of a deep brown color, a glassy, -conchoidal fracture, and a peculiar aromatic odor; it be QUINOIDINUM. 327 comes soft and tough at a moderate temperature, and melts like a resin when warmed; it is almost insoluble in water, and only partly soluble in chloroform and in glycerin, but freely soluble in diluted acids, in alcohol, and in ether. forming dark brown solutions, of an aromatic, bitter taste and odor; the alcoholic and ethereal solutions are precipitated by water, and the acid aqueous solution becomes green when first mixed with sufficient chlorine-water to decolorize it, and subsequently with an excess of aqua ammoniam. Examination: Gu-m-Resins.-About 10 grains of the triturated quinoidine are agitated, in a large test-tube, with half an ounce of water; the mixture is then heated to boiling, with constant agitation; when cool, the water must be nearly colorless, and remain so when about 10 grains of dry potassium hydrate are dissolved in the decanted water, and the whole heated; if a brown coloration takes place, in either of these tests, gum-resins (aloes) or other soluble admixtures (liquorice, glucose, dextrin, etc.) are indicated. Resins may be detected in the quinoidine remaining undissolved in the preceding test, by dissolving it, with the aid of heat, in about two drachms of diluted sulphuric acid; a complete or almost complete solution must take place, otherwise an admixture of resins, insoluble in diluted acids, is indicated. As a confirmatory test for gum-resins, liquorice, glucose, etc., a few drops of the obtained solution may be allowed to fall into alcohol; they must form a clear solution; an ensuing turbidity would establish the presence of such admixtures. Copper may be sought for, in the sulphuric-acid solution of the preceding test, by diluting it with twice its volume of water, and immersing in it, for several hours, a perfectly clean and bright iron spatula or the blade of a knife; if any copper be present, the iron will receive a slight coat of metallic copper. izfneral admixtures are indicated by a residue upon complete exhaustion of the quinoidine with alcohol, and upon incineration. 328 MANUAL OF CHEMICAL ANALYSIS. SANTONINUM. Santonin. Small, flat, rhombic prisms, transparent, without odor or color, and of a slightly bitter taste; they fuse at 1700 C., and assume, on cooling, the form of a crystalline mass; at a stronger heat, they volatilize in dense, white, irritating, inflammable vapors, which condense unaltered on cooling, forming a white crystalline sublimate; at a red heat, with free access of air, they burn away without residue. Santonin is permanent in the air, and assumes a straw-yellow color, apparently without decomposition, when exposed to the solar light. When moistened with concentrated sulphuric acid, in a dry test-tube, it remains unchanged and colorless for a while (evidence of the absence of salicin, which at once becomes scarlet red); the mixture does not assume a bluish color upon tile addition of a little powdered potassium bichromate (evidence of the absence of strychnia *), nor is it acted upon by concentrated nitric acid. Santonin is almost insoluble in cold as well as in acidulated water, and also in dilute acids; the filtered liquid has only a feebly bitter taste, and renders no precipitate with tannic acid, nor with trinitrophenol (picric acid), either before or after the addition of a little solution of sodium acetate (further evidence of the absence of salicin, and of cinchonia, and other bitter alkaloids). Boiling water dissolves L-ahth part of santonin. It is, however, readily soluble in diluted solutions of the alkaline hydrates, and in water containing them, but is reprecipitated by acids and acidulous salts. Santonin is also soluble in 43 parts of cold, and 3 parts of boiling, alcohol, in 75 parts of cold, and 2 parts of boiling, ether, in 3 parts of chloroform (distinction iromr cinchonia, which is almost insoluble in chloroform), and * Santonin and strychnia have some similarity in their appearance, and this fact has repeatedly been the cause of incidental mistakes and sad accidents. They may, however, at once be distinguished, besides their difference in taste, by the solubility of strychnia in diluted acids, by its insolubility in ether and in liquor potassme, and by its reaction with concentrated sulphuric acid, in which it dissolves without color, but produces, upon addition of a minute crystal of potassium bichromate, a bluishviolet tinge, which successively changes to violet, to red, and finally to yellow. SODIUM. 329 more or less freely in benzol, and in essential and fatty oils. The alcoholic solution burns with a pale yellow flame (evidence of the absence of an adulteration with boracic acid), and becomles transiently carmine-red upon the addition of concentrated solution of potassium hydrate. All the solutions of santonin have a bitter taste and a neutral reaction on test-papers, although it acts as an acid, forming crystallizable and soluble salts with the alkalies. SODII ACETAS. SODIUM SEU NATRIUM ACETICUM. Acetate of Sodium. Sodium Acetate. Large, colorless, transparent, striated oblique - rhombic prisms, containing three molecules (39.49 per cent.) of water of crystallization, which gradually evaporate upon exposure to a dry, warm air, leaving the anhydrous salt as a white powder. When heated, in a dry test-tube, the crystals undergo aqueous fusion at 288~ C., and, upon continued heating, they give out their water of crystallization, and are decomposed, with the evolution of empyreurnatic, inflammable fumes, leaving a black residue of carbon and sodium carbonate, which imparts to the flame a yellow color, blues moistened red litmus-paper, and effervesces with acids. Sodium acetate is soluble in from two to three parts of cold, and in less than its own weight of boiling, water; it is also soluble to some extent in alcohol; its aqueous solution is neutral or nearly so, has a cooling, saline taste, is not precipitated when dropped into strong alcohol, nor when mixed with a diluted solution of sodium carbonate, or with a concentrated soIntion of sodium bitartrate; it assumes a red color upon the addition of a few drops of solution of a ferric salt, evolves the vapor of acetic acid, when warmed with concentrated sulphuric acid, and that of acetic ether, when heated with a mixture of' alcohol and sulphuric acid. For Volumetric Estimation, see page 58. 330 MANUAL OF CHEMICAL ANALYSIS. Examination: Sodiuzm chloride and sulvphate are detected, in the solution of sodium acetate, acidulated with a few drops of diluted nitric acid, by testing it, in separate portions, with argentic nitrate and barium nitrate; a white precipitate with the first reagent would indicate chloride, and with the second one, suljhate. ietallic impurities are detected by mixing a concentrated solution of the salt with an equal volume of hydrosulphuric acid, and by subsequent addition of a little aqua ammonia. SODII ARSENIAS. SODIUM SEU NATRIUM ARSENICUM. Arseniate of Sodium. Sodium Arseniate. Colorless, transparent, prismatic crystals, containing 14 molecules (40.38 per cent.) of water of crystallization, 10 of which are slowly given off at common temperatures, and in dry air, leaving a white powder still containing four molecules of water; these, however, are driven out at 148~ C., when the salt fuses. Sodium arseniate dissolves in about three parts of cold water, forming an alkaline solution, of a mild, feebly saline taste, which gives white precipitates with barium and calcium salts, and with magnesium and zinc sulphates, and a brick-red one with argentic nitrate, all of which are soluble in nitric acid; it suffers no alteration by hydrosulphuric acid, either in its alkaline solution or when this is acidulated with acids; the latter mixture, however, becomes turbid upon warming, separating white sulphur first, and yellow arsenic disulphide afterward. Fused upon charcoal, before the blow-pipe, sodium arseniate gives the garlic-like odor of arsenic, and imparts a yellow color to the flame; heated, in a narrow tube, with a little potassium cyanide, it forms a metallic mirror. SODIUM. 331 SODII BIBORAS. BORAX. SODIUM SEU NATRIUM BIBORICUM. Biborate of Sodium. Borax. Sodium Biborate. Colorless, transparent, hard, six-sided prisms, containing 10 molecules (30.82 per cent.) of water of crystallization, ordinarily permanent, but slightly efflorescent in dry and warm air; when heated, they undergo aqueous fusion, give off the water, swell up, and form a white porous mass, which fuses at a red heat into a glass, which is a powerful solvent for the metallic oxides, forming colored fluxes. When powdered borax is mixed in a porcelain capsule with diluted sulphuric acid and subsequently with alcohol, and the mixture ignited, the alcohol burns with a greenish flame. Sodium biborate is soluble in 12 to 15 parts of cold, and two parts of boiling, water, and, with the aid of heat, in its own weight of glycerin, but insoluble in alcohol; its aqueous solution has an alkaline, sweetish taste, and an alkaline reaction upon litmus and especially upon turmeric paper; it forms precipitates of insoluble or sparingly soluble borates with the solutions of most earthy and metallic salts, and acts upon salts of gold, silver, mercury, and others, all-nost like potassium hydrate, precipitating their hydrates. When added to mucilage of gum-arabic or Iceland-moss, or to other similar vegetable mucilages, solution of sodium biborate thickens them considerably, unless they contain an addition of grape or cane sugar. For Volumetric Estimation, see page 58. Examination: One drachm of the powdered borax, when dissolved in two ounces of warm water, should yield a complete and clear solution, remaining so after cooling; this solution may serve for the following tests: Sodium carbonate is indicated by effervescence, or the rise of gas-bubbles, when a portion of the solution is added to concentrated hydrochloric acid. Alum is indicated by a white precipitate with solution of sodium carbonate. 332 MANUAL OF CHEMICAL ANALYSIS. Chloride and sulphate may be detected in the solution, after dilution with three times its volume of water and acidulation with diluted nitric acid, by the formation of white precipitates when tested, in separate portions, with argentic nitrate for chloride, and with barium nitrate for sulphate. Phosphate may be detected by a white granular precipitate, when the solution is mixed with nearly an equal volume of solution of ammoniated magnesium sulphate. In order to ascertain the absence of arsenic acids, which would render the same reaction, the precipitate may be collected, washed, and dried, and then tested by heating a portion of it, mixed with a little exsiccated sodium carbonate, upon charcoal, and another portion, with a little potassium cyanide, in a narrow glass tube; a garlic-like odor in the first test, and a metallic mirror in the second, would indicate an incidental contamination with an arsenite or arsenate. Metallic impurities are detected by mixing the solution of the salt with an equal volume of hydrosulphuric acid, and by subsequent acidulation with diluted hydrochloric acid. SODII BICARBONAS. SODIUM SEU NATRIUM BICARBONICUM. Bicarbonate of Sodium. Sodium Bicarbonate. White, opaque masses, made up of aggregations of small, oblique, four-sided plates or irregular scales, of a white appear - ance, in consequence of a slight efflorescence of the surfaces of the crystals, or a snow-white powder. The salt contains two molecules (10.65 per cent.) of water of crystallization, and is permanent in the air. Exposed to a strong heat, sodium bicarbonate loses the water of crystallization and one molecule of carbonic acid, amounting together to 36.8 per cent. by weight, and anhydrous sodium carbonate remains behind. Sodium bicarbonate is soluble in 13 to 14 parts of water at 15.50 C., and in 10 parts at 240 C., forming a solution of a mild, SODIUM. 333 alkaline taste and reaction; when heated, effervescence takes place, and at the boiling-point of the solution the salt is converted into sodium carbonate and sesquicarbonate. Solution of sodium bicarbonate affords no precipitate upon the admixture of a concentrated solution of sodium bitartrate or of tartaric acid. One drachm of crystallized sodium bicarbonate saturates 49.98 grains of citric acid, and 53.55 grains of tartaric acid. For VoIumetric Estimation, see page 58. Examination: Sodiurm mono-carbonate may be recognized in the solution of the salt by a white precipitate, when tested with magnesium sulphate. A confirmatory test is to mix a solution of 4- grains (0.3 gramnme) of mercuric chloride in 11 drachm of water, with a solution of half a drachm (2.0 grammes) of the sodium bicarbonate in I ounce of cold water, and to allow the mixture to stand for about three minutes, when only a slight white turbidity should have occurred; a reddish-brown deposit would confirmn the presence of mono-carbonate. Sodiuzn, chloride and sulphate are detected in the solution of the salt, when over-saturated with diluted nitric acid, by testing it in separate portions, with argentic nitrate for chloride, and with barium nitrate for sulphate. If a precipitate is formed with the argentic nitrate, which gradually turns gray or grayish black, the presence of sodium hyposu12phite is also indicated. fMetals.-About ten grains of the powdered sodium bicarbonate are dissolved in about one ounce of hydrosulphulic acid, and, when solution has taken place, this is over-saturated with diluted nitric acid; a dark turbidity, occurring either before or after acidulation, would indicate metallic impurities; these, if considerable in amount, may be obtained as a precipitate from a larger quantity of the salt, and the nature of the metals determined by the methods described on pages 41 and 42. The occurrence of a slight white turbidity, upon the addition of the acid, would be due to the presence of traces of sodium hyposulphite. 334 MANUAL OF CHEMICAL ANALYSIS. SODII CARBONAS. SODIUM SEU NATRIUM CARBONICUM. Carbonate of Sodium. Sodium Carbonate. Large, colorless, transparent, oblique-rhombic prisms, containing 10 molecules (62.85 per cent.) of water of crystallization; they effloresce in dry air, lose their water, and crumble to a white powder; when exposed to heat, they undergo aqueous fusion, and, after the evaporation of the water, the anhydrous salt fuses at a red heat without undergoing further change. Crystallized sodium carbonate dissolves in two parts of cold, and in less than half its weight of boiling, water; or in other words, 100 parts of water dissolve, at 14~ C., 60.4 parts, at 360 C., 833 parts, and at 104~ C. (the boiling-point of the saturated solution), 445 parts, of crystallized sodium carbonate.* The salt is insoluble in alcohol. Its aqueous solution has a strong alkaline taste and reaction; dropped into solution of tartaric acid, it produces no precipitation; it effervesces with acids and acidulous salts, and decomposes the soluble salts of the earthy and heavy metals, forming, with most of them, insoluble or sparingly soluble carbonates or hydrates. One drachm of crystallized sodium carbonates saturates 29.34 grains of citric, and 31.47 grains of tartaric, acid. For Volumetric Estimation, see page 58. Examination: Sodium Chloride, Sulphate, and Ifyposuphite.-A solution of the sodium carbonate is over-saturated with diluted nitric acid, and is subsequently tested in separate portions, with barium nitrate for sulphate, and with argentic nitrate for chloride; if the latter reagent causes a white precipitate which soon turns more or less gray or grayish black, it would also indicate the presence of sodium hyposulphite. * Sodium carbonate, with ten molecules of water of crystallization, is altered in its solution, at near the boiling-point, into a salt with only one molecule of water of crystallization, which is less soluble, and gives rise to the anomaly in the solubility of sodium carbonate. A similar instance is met with in sodium sulphate and several other salts. SODIUM. 335 Arsenic.-About one ounce of the crystallized salt is dissolved in 4 ounces of water, the solution is slightly over-saturated with concentrated hydrochloric acid, is filtered, and then is warmed to about 60 to 70~ C.; while still warm, hydrosulphuric-acid gas is allowed to pass into the solution until it is nearly cooled, the flask is then corked, and allowed to stand for 12 hours, when a flocculent yellow precipitate would indicate the presence of arseniate. As a confirmatory test, about 10 grains of the powdered salt are dissolved in half a fluidounce of concentrated hydrochloric acid, and then 20 drops of concentrated solution of stannous chloride and subsequently about one fluid-drachm of concentrated sulphuric acid are added, and the whole, if necessary, is heated nearly to boiling. The formation of a brown turbidity would verify the presence of arsenic. SODII CHLORIDUMo SODIUM SEU NATRIUM CHLORATUM. Chloride of Sodium. Common Salt. Sodium Chloride. Anhydrous, colorless, transparent, cubical crystals, often agglomerated into hollow, quadrangular pyramids, or a white, granular powder, having a spec. grav. of 2.15; permanent in the air, but slightly deliquescent when containing traces of magnesium and calcium chlorides. When exposed to heat, sodium chloride decrepitates, from the presence of interstitial moisture, melts at a red heat, and volatilizes with partial decomposition at a high temperature. It imparts a yellow color to the flame, and evolves vapors of hydrochloric acid, when heated with strong sulphuric acid. Sodium chloride is almost equally soluble in water at all temperatures: 100 parts of water dissolve at 0~ C. 35.52 parts, at 14~ C. 35.87 parts, at 25~ C. 36.13 parts, at 40~ C. 36.64 parts, at 80~ C. 38.22'parts, at 100~ C. 39.61 parts, and at 1100 C., the boiling-point of the saturated solution, 40.35 parts, of 336 MANUAL OF CHEMICAL ANALYSIS. the salt; it is also soluble in glycerin, but not perceptibly soluble in absolute alcohol, in ether, or in chloroform, but its solubility in alcohol increases with the quantity of water contained therein. Its aqueous solution is neutral, and remains colorless upon the addition of chlorine-water (distinction from the alkaline bromides); it forms white precipitates with the solutions of those metallic salts whose chlorides are quite or almost insoluble in water-for instance, with the salts of silver, bismuth, and lead, and with the subsalts of mercury. Examination: lMagnesium and calciyum chlorides are detected in the solution of sodium chloride by a white turbidity taking place upon the addition of a diluted solution of sodium carbonate. They may be distinguished by completely precipitating a warm dilute solution of sodium chloride, after the addition of a few drops of aqua ammonie, with ammonium oxalate; if this causes a precipitate, it eliminates only the calcium without acting upon the magnesium salt; after a while the liquid is passed through a filter, and the filtrate tested, with a few drops of sodium phosphate, for magnesium salts, which, when present, will give rise to the formation of a white precipitate, soluble upon the addition of acetic acid. Alkaline and earthy sul2hates are recognized in tile dilute solution, acidulated with hydrochloric acid, by a white precipitate with barium chloride. lfetallic impurities may be detected by the occurrence of a dark coloration or precipitate, when the solution of the salt is mixed with an equal volume of hydrosulphuric acid, and subsequently over-saturated with aqua ammonia. Iodides and Bromides.-A glass tube of about 20 inches in length, and one-half to three-fourths of an inch wide, which is drawn out at its lower end into a narrow aperture, is filled to about 16 inches with the powdered salt, and this percolated with about 4 ounces of alcohol, of a spec. g/iav. between 0.834 and 0.864, and the obtained percolate evaporated to dryness at a gentle heat. The residue thus obtained is dissolved in a little water, the solution slightly acidulated with diluted sulphuric acid, and a little mucilage of starch is first added, and subsequently a little chlorine.water, drop by drop, and with SODIUM. 337 gentle stirring with a glass rod. The presence of even minute traces of iodine will cause a bluish coloration of the fluid; when iodine alone is present, the blue color will gradually become purple, and decrease, until it finally disappears; but, when bromine is also present, the blue color will not turn purple, but brownish, then orange, and finally yellow. Nitrate.-To a little strong sulphuric acid is added part of a drop of sulphuric-acid solution of indigo, so as to communicate to the acid a bluish tint. An equal volume of concentrated solution of the salt is then added, keeping the mixture cool; if nitrate be present, the blue tint will disappear. A confirmatory and still more sensitive test is to dip a bright ___, -zinc rod into a test-tube, or to suspend it in a small beaker (Fig. 87) containing a little diluted sulphuric-acid mucilage of FIG. 8T. starch, to which one drop of solution of pure potassium iodide, and subsequently twice the bulk of the liquid of a solution of the salt, has been added; if nitrate be present, a bluish coloration of the liquid will issue from the zinc. _Moistqure.-When the quantity of water in sodium chloride has to be estimated, 10 scruples of the salt are weighed into a tared, dry beaker, or porcelain dish; this is covered with bibulous paper, and allowed to stand in a warm, dry place, at nearly 100~ C., for several days, or until no more loss of weight takes place; the whole is then weighed, and the loss of weight, multiplied by 10, indicates the percentage of moisture contained in the salt. SODII HYDRAS. SODA. SODIUM SEU NATRIUM HYDRICUM. NATRIUM CAUSTICUM. Soda. Sodium HTydrate. Hard, white, fusible masses, in flat, tabular fragments or sticks, of a fibrous fracture, or a coarse, white powder; very 22 838 MANUAL OF CHEMICAL ANALYSIS. deliquescent, but solidifying again after a time, in consequence of the absorption of carbonic-acid gas, and the formation of sodium carbonate. Heated upon the looped end of a platinum wire, it imparts a yellow color to the flame. Sodium hydrate is very soluble in water, with the evolution of heat; it is also freely soluble in alcohol; its solutions are highly alkaline and caustic, and act destructively upon animal tissues. Dropped into a diluted solution of plumbic acetate, it causes a white turbidity, which disappears again upon continued addition of the caustic solution, without leaving a black residue (evidence of the absence of sodium sulphide). When the concentrated aqueous solution is dropped into strong alcohol, no precipitate should take place, as its appearance would indicate the presence of sodium carbonate, sulphate, chloride, or other salts, less soluble in alcohol. Sodium hydrate may readily be distinguished from potassium hydrate, by dropping concentrated solutions of the salts into solution of tartaric acid, taking care that the acidity of the solution remains prevalent; sodium hydrate will yield no precipitate unless containing potassium hydrate to a considerable extent, while potassium hydrate forms a white, granular precipitate. For Volumetric Estimation, see page 58. Examination: Sodium, carbonate may be detected in the hydrate by effervescence, or by the formation of gas-bubbles, when a small piece of the hydrate is thrown into acetic acid, and by the occurrence of a white turbidity upon the admixture of an equal volume of lime-water with the aqueous solution of the salt. Chloride and sulphate are detected in the diluted solution, when over-saturated with diluted nitric acid, and tested in separate portions, with argentic nitrate for the former, and with barium nitrate for the latter. Silicic acid and aluminium salts may be detected by oversaturating the dilute solution of sodium hydrate with an excess of diluted nitric acid, and subsequently evaporating to dryness; the residue is dissolved in warm water, and should be wholly soluble; an insoluble residue would indicate silicic acid; the solution is filtered, and the filtrate tested with aqua ammonioe; SODIUM. 339 the formation of a white, gelatinous precipitate would indicate aluminium salts. SODII HYPOPHOSPHIS. SODIUM SEU NATRIUM HYPOPHOSPHOROSUM. Hypophosphite of Sodium. Sodium Hypophosphite. Small, colorless, transparent, rectangular tables, of a pearly lustre, or a white, granular powder, which, when heated in a dry test-tube, will first give off moisture, and subsequently phosphoretted hydrogen, burning with a bright light; a residue of sodium pyrophosphate, reddened by traces of red amorphous phosphorus, is left behind. Sodium hypophosphite is deliquescent if not dry, or in a moist atmosphere; it is readily soluble in water, and in absolute alcohol (distinction from calcium hypophosphite), but insoluble in pure ether; its aqueous solution has a slightly alkaline reaction, and is gradually oxidized on exposure, especially when warm; it affords, when much diluted, no reaction with diluted sulphuric acid, or with calcium chloride (distinction from soluble phosphates and phosphites), nor does it render a precipitate with oxalic acid (further evidence of the absence of calcium -salts); it acts as a powerful reducing agent, and forms a white precipitate with argentic nitrate, which quickly turns brown, and is converted into metallic silver. SODIn HYPOSULPHIS. SODIUM SEU NATRIUM HYPOSULPHUROSUM SEU SUBSULPHUROSUM, Hyposulphite of Sodium. Sodium flyposulphite. Sodium Dithionate. Large, colorless, transparent, right-rhombic, striated prisms, containing five molecules (41.7 per cent.) of water of crystalli 340 MANUAL OF CHEMICAL ANALYSIS. zation; permanent at ordinary temperatures, but efflorescent in dry and warm air; when exposed to heat, the crystals undergo aqueous fusion, and then dry up again into a white mass, which, when the heat is increased, are decomposed, with the evolution of vapors of sulphurous acid and sulphur, which take fire, and burn away, leaving behind a residue of neutral sodium sulphate, containing a little sulphide. Sodium hyposulphite is soluble in 1. part of cold water, but insoluble in alcohol; its solution has a cooling and afterward a bitter taste, and a feebly alkaline reaction; on exposure to the air, it is gradually decomposed, the hyposulphite being converted into sulphur and sodium sulphite, which latter salt, on the exposure of the solution to the air, is further decomposed into sulphur and sodium sulphate; when dropped into diluted hydrochloric, nitric, or sulphuric acid, solution of sodium hyposulphite gradually becomes turbid, sulphur being precipitated, and sulphurous acid disengaged. With solution of barium chloride, a concentrated solution of sodium hyposnlphite forms a white precipitate, which dissolves, however, upon sufficient dilution with water (evidence of the absence of sodium sulphate); when dropped into dilute solution of argentic nitrate, a white precipitate is formed, which soon turns yellow, and finally black; when, however, on the other hand, the argentic solution is dropped into the solution of sodium hyposulphite, the ensuing white precipitate of argentic hyposulphite is redissolved upon agitation, and the solution remains clear as long as sodium hyposulphite is in excess. When iodine, either alone or dissolved in alcohol, is added to solution of sodium hyposulphite, it is immediately decolorized, sodium iodide and tetrathionate being formed; this process takes place in the proportion, approximately, of one part (127) of iodine to two parts (248) of crystallized sodium hyposulphite; a solution in these proportions dissolves iodine readily, with a brown color, but it is decolorized again upon the restoration of those proportions by the addition of sodium hyposulphite. Solution of sodium hyposulphite is a solvent for several otherwise insoluble compounds, as argentic oxide, argentic iodide, SODIUM. 341 bromide, and chloride, plumbic iodide, plumbic and calcium. snlphates, etc. For Volumetric Estimation, see page 63. Examination: Sodium sulphate is detected by the occurrence of a white precipitate, when the dilute solution of the salt is tested with barium nitrate. Sodium carbonate is indicated by effervescence when a concentrated solution of the salt is dropped into diluted acetic or hydrochloric acid. SODIM IODIDUM. SODIUM SEU NATRIUM IODATUM. Iodide of Sodium. Sodium Iodide. A white, granular, deliquescent powder, or colorless, striated, oblique-rhombic prisms, with four molecules of water of crystallization, when crystallized at temperatures below 30~ C., and anhydrous cubes when obtained at temperatures above that point. When exposed to heat, sodium iodide fuses, and is volatilized at a higher temperature, giving off part of its iodine; it is decomposed at a strong heat; when a few grains of the salt are heated in a test-tube, either in concentrated sulphuric acid, or with a little potassium bisulphate, violet-colored vapors of iodine are evolved; when a few grains are dissolved in chlorine-water, the latter assumes a brown color, and, when shaken with some chloroform or carbon bisulphide, and subsequently with a little water added, imparts a fine purple color to the chloroform or carbon bisulphide. Sodium iodide is freely soluble in water, in glycerin, and in alcohol; 100 parts of water, at 14~ C., dissolve 173 parts of the salt; the solution has an acrid, saline taste, and a feeble, alkaline reaction; it gives no precipitate with tartaric acid, with sodium bitartrate, or with sodium carbonate, but forms a yellowish one with argentic nitrate, insoluble in diluted nitric acid, and but very sparingly soluble in ammonium hydrate, 342 MANUAL OF CHEMICAL ANALYSIS. and a vermilion-red one with mercuric chloride, soluble in excess of either reagent. Examination: Impurities and admixtures, less soluble in alcohol, are indicated by a white turbidity or granular deposit, when a saturated aqueous solution of the salt is dropped into an excess of alcohol fortius. Potassium salts are indicated by a white, crystalline precipitate in the concentrated aqueous solution, when added to a strong solution of sodium bitartrate. Chloride and bromide may be detected by completely precipitating a warm aqueous solution of the salt, acidulated with a few drops of nitric acid, with argentic nitrate; the precipitate is separated from the menstruum, as much as practicable, by decantation, is washed, and then agitated with a little dilute aqua ammonie; the liquid is then filtered, and the filtrate oversaturated with nitric acid; an opalescence of the liquid will take place; a precipitate would indicate chloride or bromide. If a precipitate be formed, it may be collected upon a filter, washed, FIG. 88. and subsequently removed into a test-tube, by piercing the filter, and rinsing the precipitate into the tube by means of a washing-bottle; after subsiding, the supernatant water is drawn off, SODIUM. 343 and the precipitate agitated with chlorine-water; if argentic chloride, it remains unchanged; if bromide, the chlorine-water will assume a yellowish or reddish color, which, on agitation with chloroform, will be transferred to the latter. Carbonate may be detected, in the aqueous solution, by a white turbidity when mixed with twice or thrice its volume of lime-water. Sodium ntitrate may be detected, when 10 grains of the sodium iodide and 12 grains of argentic sulphate are triturated together, with a little water; the mixture is then transferred to a small, tared, moist filter, and the filtrate mixed with an equal volume of concentrated solution of ferrous sulphate, and subsequently placed upon concentrated sulphuric acid (Fig. 88); a dark coloration of the line of junction of the two liquids would indicate nitrate. The precipitate upon the filter is washed with tepid water, until this, when allowed to drop into dilute hydrochloric acid, ceases to produce a turbidity; the precipitate is then washed with a little greatly-diluted aqua ammonite, and subsequently dried at a temperature not exceeding 90~ C.; it must weigh not less than 15 grains, if the sodium iodide employed was pure. For Volumetric Estimation, see page 62. SODII NITRAS. SODIUM SEU NATRIUM NITRICUM. Nitrate of Sodium. Chili Salpetre. Sodium Nitrate. Anhydrous, colorless, transparent, obtuse - rhombohedral crystals, slightly deliquescent, and generally of a mlfoist appearance; when thrown upon burning coals, the salt deflagrates with an orange-yellow flame. Sodium nitrate is freely soluble in water, but only sparingly in alcohol; the aqueous solution, saturated at 18.5~ C., contains 46.81 per cent., and saturated at its boiling-point (121~ C.), nearly 70 per cent., of the salt; the solution is neutral, has 344 MANUAL OF CHEMICAL ANALYSIS. a sharp, cooling, saline taste, and is not acted upon, when diluted, by reagents. Its concentrated solution may readily be distinguished from that of potassium nitrate by not being acted upon by a solution of sodium bitartrate, which gives a white, granular precipitate with potassium nitrate. Examination: Salts of the earthy oxides are detected in the solution of sodium nitrate, by a white turbidity, upon the addition of solution of sodium carbonate. Chlorides and sulphates are detected in the diluted solution, after acidulation with diluted nitric acid, by white precipitates when tested, in separate portions, with argentic nitrate -for chloride, and with barium nitrate for sulphate. _Metals are detected by a dark coloration or precipitate, when the concentrated solution of the salt is mixed with an equal volume of hydrosulphuric acid. Sodium Iodide and Iodate.-About two drachms of the salt are dissolved in one ounce of water, and the solution is equally divided into two test-tubes, to one of which a little sulphuricacid mucilage of starch is added; an ensuing blue coloration would indicate either sodium iodide and iodate or sodium io~dide and nitrite. When no blue reaction takes place, to the second part of the solution is also added a little sulphuric-acid mucilage of starch, and it is divided into two portions, and tested severally with one drop of solution of potassium nitrite, in the one, and in the other by adding, drop by drop, a little hydrosulphuric acid. An ensuing blue reaction, in the first instance, would indicate the presence of sodium iodide; a reddish, purple, or violet coloration, in the second one, sodium iodate. Another test for iodide and iodate is to add, to a concentrated aqueous solution of the sodium nitrate, some chlorinewater, and to agitate the mixture afterward with carbon bisulphide; the latter, when it has subsided, is separated by means of a pipette, and agitated with a little powdered zinc and a few drops of diluted sulphuric acid; a purple coloration of the carbon bisulphide, either at once or upon the latter treatment, would confirm the presence of iodine compounds. SODIUM. 345 SODII PHOSPHAS. SODIUM SEU NATRIUM PHOSPHORICUM. Phosphate of Sodium. Tri-basic Sodium Phosphate. Colorless, transparent, oblique-rhombic prisms, terminated by four converging planes, containing 24 molecules (60.10 per cent.) of water of crystallization; they are readily efflorescent, losing, when exposed to the air at common temperatures, 10 molecules (22.25 per cent.) of water, and becoming opaque; when heated to near 100~ C., the rest of the water of crystallization evaporates. When exposed to a strong heat, sodium phosphate first undergoes aqueous fusion, and afterward melts at a red heat into a limpid glass of sodium pyrophosphate, which becomes opaque on cooling. Sodium phosphate dissolves in 6 parts of cold, and in 2 parts of boiling, water, but is insoluble in alcohol. Its solution has a cooling, saline taste, a faintly alkaline reaction, affords no effervescence upon addition of an acid, and gives, with solution of completely neutral (fused) argentic nitrate,: a bright-yellow precipitate, soluble in both ammoniuml hydrate and nitric acid; the amnmoniacal solution remains unchanged, when the testtube, wherein it is contained, is immersed in boiling water (distinction from the similar argentic arsenite, whose ammoniacal solution deposits metallic silver upon the walls of the test-tube upon warming). With solution of ammoniated magnesium sulphate, sodium phosphate gives a white precipitate, insoluble in an excess of the salt as well as of the reagent. Examination: Sodiizm carbonate is detected by effervescence, upon the addition of hydrochloric acid to the concentrated solution of the salt. S2dlphates and chlorides are detected in the diluted solution, strongly acidulated with nitric acid, when tested in separate portions, with barium nitrate for sulphate, and with argentic nitrate for chloride. iletallic Impurities.-About half an ounce of the salt is dissolved in one ounce of boiling water, and the solution added to about 3 ounces of hydrosulphuric acid in a flask; about one 346 MANUAL OF CHEMICAL ANALYSIS. drachm of diluted hydrochloric acid is added, and the flask corked and allowed to stand in a warm place for about 12 hours. A yellow precipitate would indicate arsenic, a dark one metallic impurities. As a confirmatory test, or if the presence of other metals requires. a special test for arsenic, 20 grains of the sodium phosphate are dissolved in about one drachml of boiling water in a wide test-tube; half a fluidounce of pure, concentrated hydrochloric acid is then added, and a strip or roll of bright copperfoil completely immersed in the fluid; the tube is then dipped into boiling water, and allowed to stand therein for half an hour. The copper must remain bright; a grayish or grayishblack coating of the copper would be evidence of the presence of arsenic. SODII PYROPHOSPIrAS. SODIUM SEU NATRIUM PYROPHOSPHORICUM. Pyrophosphate of Sodium. Sodium Pyro- or Tetraphosphate. Colorless, transparent, brilliant, rhomboidal plates, or a white granular powder, containing ten molecules of water of crystallization, permanent in the air; when exposed to heat, the salt gives off its water of crystallization, fuses, and, on cooling, concretes to a crystalline semi-transparent mass. Sodium pyrophosphate dissolves in ten parts of cold water, forming a slightly alkaline solution, which renders a white precipitate and a neutral menstruum with argentic nitrate, and a white granular precipitate with ammoniated magnesium sulpliate, insoluble in an excess of either the reagent or the salt. When solution of sodium pyrophosphate is boiled for some time, the salt returns to the state of the tri-basic phosphate, and regains the properties, and renders the reactions, of tri-basic sodium phosphate (page 345). Examination: Carbonate is detected in the solution of the salt, by effervescence upon the addition of a little concentrated nitric acid. SODIUM. 347 Sulphate and chloricde may be detected in the diluted solution, after acidulation with nitric acid, by white precipitates when tested in separate portions, with barium nitrate for the former, and with argentic nitrate for the latter. iMetallic impurities are detected by mixing the concentrated solution of the salt with an equal volume of hydrosullphuric acid, and subsequently acidulating with diluted nitric acid. SODII SULPHAS. SODIUM SEU NATRIUM SULPHURICUM. Sulphate of Sodium. Glauber's Salt. Sodium Sulphate. Colorless, transparent, six-sided, striated, oblique prisms, containing ten molecules (56 per cent.) of water of crystallization, efflorescent, and gradually losing water and crumbling to a white powder. Exposed to heat, the crystals undergo first aqueous, and subsequently igneous, fusion. Sodium sulphate is very soluble in water; 100 parts of water at 0~ C. dissolve 12 parts, at 18~ C. 48 parts, at 25~ C. 100 parts, and at 33~ C. 322.6 parts, of the crystallized salt; above that temperature the salt passes into the anhydrous state, in which it is less soluble, and the solution then separates salt upon an increase of heat (see foot-note on page 334). The solution has a salty and feebly bitter taste, is neutral, remains unaltered with sodium carbonate as well as with sodium bitartrate, and gives a granular white precipitate with lime-water, and a copious white one with solutions of both barium and lead salts, which latter precipitates are insoluble in diluted acids. Fifty grains of crystallized sodium sulphate, dissolved in two ounces of water acidulated with hydrochloric acid, give, when completely precipitated with barium chloride, a precipitate which, when collected upon a tared filter, washed, and dried, should weigh 72.2 grains. Examination: A solution of one part of the crystallized salt in four parts 348 MANUAL OF CHEMICAL ANALYSIS. of water, tested with blue and with red litmus-paper, must not change the color of either. Chloride may be detected in the diluted solution, acidulated with nitric acid, by a white turbidity or precipitate with argentic nitrate. Ammonium sulphate may be recognized by the odor as well as by the rise of white vapors, when a little of the triturated salt is heated in a strong solution of potassium hydrate and a glass rod, moistened with acetic acid, is held in the orifice of the test-tube. Mlagnesiumn and calcium salts are detected in the solution by a white precipitate with sodium carbonate; a reddish or brownish appearance of the precipitate would indicate metallic impurities (iron and manganese); the presence of manganese salts may be confirmed by a brown precipitate upon the addition of' solution of chlorinated lime to the solution of the sodium sulphate, that of iron by a blue turbidity, when the solution of the salt is acidulated with hydrochloric acid and tested with potassium ferrocyanide. ietals may further be detected in the diluted solution by introducing ammonium sulphydrate, and allowing the mixture to stand for a few hours; a white turbidity would indicate zinc, and a brownish-black one, copper; a greenish-black one would confirm the presence of iron, and a pale-reddish one, that of manganese. If a test for arsenic is required, about 30 grains of the crystallized sodium sulphate are dissolved in one drachmn of warm water in a wide test-tube; half a fluidounce of concentrated hydrochloric acid is added, and a strip or roll of bright copperfoil completely immersed in the fluid; the tube is then dipped into boiling water and allowed to stand in the water for half an hour. The copper must remain bright; a grayish-black coating would indicate arsenic. Sulphite and hyposulphite may be detected in a solution of one part of the salt in three parts of water, by mixing it with one-third of its volume of concentrated hydrochloric acid, and heating it gently with a few grains of granular zinc; the presence of either of the above salts will give rise to the formation of hydrosulphuric acid, which may be recognized by placing a SODIUM. 349 small bunch of cotton, moistened with solution of plumbic acetate, in the orifice of the tube, or by closing it with bibulous paper moistened with the plumbic solution (Fig. 89). FIG. 89. A black coloration of the solution would show the presence of either or both the above salts. 350 MANUAL OF CHEMICAL ANALYSIS. SODII SULPHIS. SODIUM SEU NATRIUM SULPHUROSUM. Sulphite of Sodium. Sodium Sulphite. Colorless, opaque, prismatic crystals, containing seven molecules (50 per cent.) of water of crystallization; on exposure to the air they effloresce somewhat, and the salt is gradually converted into sulphate, emitting a feeble odor of sulphurous acid. This liability to decomposition is retarded, and the salt made more permanent, by exsiccating it at a gentle heat, when it undergoes aqueous fusion, loses its water of crystallization, and becomes white. It is this form in which sodium sulphite is now frequently met with. When this salt is exposed to a strong red heat, it fuses to a dirty yellowish mass, consisting of sodium sulphate and sulphide, which may be separated by extracting the cold residue with strong alcohol, which dissolves the sulphide, but not the sulphate. Crystallized sodium sulphite is soluble in 4 parts of cold, and in less than its own weight of boiling, water, but only,paringly in alcohol; its aqueous solution has a feeble alkaline reaction, and becomes turbid upon heating, but limpid again on cooling; on exposure of the solution to the air, the sulphite is gradually converted into sulphate with the separation of sulphur, as it is also by treatment with oxidizing agents, snch as chlorine, hypochlorous acid, nitrous acid, etc. When acidulated, solution of sodium sulphite acts as a powerful reducing agent; it emits sulphurous acid upon the addition of strong acids, slowly when cold, freely on warming, and with the separation of sulphur; when this test is performed with hydrochloric or sulphuric acid, and with the addition of a little zinc, hydrosulphuric acid is evolved. With barium chloride or nitrate, solution of sodium sulphite forms white precipitates, soluble in diluted hydrochloric acid. Examination: Sodium scul2pate may be detected in the diluted solution of the salt, by precipitating it with barium chloride, and by decantation of the supernatant menstruum after subsiding; the precipitate is once or twice washed with a little cold water, and SPIRITUS. 351. then treated with diluted hydrochloric acid, wherein it should be wholly soluble; an insoluble residue will indicate the presence of sulphate. SPIRITUS IETHERIS NITROSI. SPIRITUS NITROSO-2ATHEREUS. SPIRITUS NITRI DULCIS. Sweet Spirit of Nitre. Spirit of _Nitrous Ether. Alcoholic Solution of Ethyl Nitrite. A colorless, or pale-yellow, volatile liquid, of a fragrant, ethereal odor, and sharp, aromatic, sweetish taste; its spec. grav. is 0.837 U. S. Pharm., 0.845 Brit. Pharm., and 0.8400.850 Pharm. Germ., and it should contain between 4 and 5 per cent. of ethyl nitrite. It is inflammable, reddens blue litmus-paper not at all or only faintly, and assumes a dark cilor upon the addition of a few drops of a solution of ferrous chloride. Spirit of nitrous ether is miscible with water, alcohol, chloroform, ether, carbon bisulphide, benzol, and essential and fatty oils. A portion of the spirit, in a test-tube half filled with it, plunged into water heated to 63~ C., and held there until it has acquired that temperature, will boil distinctly on the addition of a few small pieces of glass. Examination: Aldehyde is indicated by a brown coloration of the spirit when agitated in a test-tube with a few fragments of fused potassium hydrate. Acids. —Spirit of nitrous ether containing so much of free acid as to have a perceptible sour taste and an acid reaction upon blue litmus-paper, and to cause the rise of gas-bubbles from a few crystals of potassium bicarbonate when dropped into it, cannot be considered admissible for medicinal use. Ethyt chloride may be detected by burning away a small quantity of the spirit upon a little water in a porcelain capsule, and by subsequently testing the water, after acidulation with a few drops of nitric acid, with a few drops of solution of argentic nitrate; the occurrence of a white turbidity would indicate the presence of ethyl chloride. 352 MANUAL OF CHEMICAL ANALYSIS. Jfethylic Alcohol.- About one ounce of the spirit is shaken with 30 to 40 grains of anhydrous (exsiccated) potassium carbonate; after subsiding, the supernatant spirit is decanted; about half a fluidounce of this dehydrated spirit is introduced into a small flask, or a test-tube of a proper size (Fig. 90), 21 FIG. 90. drachms of anhydrous calcium chloride in powder are added, and, after thoroughly mixing, the flask is connected with a condenser, and is then placed in a water-bath for distillation; this distillation is continued until one and a half fluid-dracinm of distillate have been obtained. The test-tube is then removed from -the water-bath, and, when cool, one drachm of water is added, and the distillation once more resumed until a little more than half a fluid drachm of distillate is obtained. The latter distillate is mixed with half an ounce of water, wherein 30 grains of potassium bichromate and 30 drops of concentrated sulphuric acid have been dissolved. After having allowed the mixture to stand for a quarter of an hour, it also is submitted to distillation, until half an ounce of distillate is obtained; to this 30 grains of crystallized sodium carbonate are added, in a porcelain capsule, and the whole evaporated to half its bulk; it is then slightly over-saturated with acetic acid, filtered into a testtube, and a solution of one grain of argentic nitrate in half a drachn of water acidulated with two drops of diluted acetic SPIRITUS. 353 acid added, and the whole gently boiled for about two minutes. If the spirit is free from methylic alcohol, the solution darkens, and often assumes transiently a purplish tinge, but continues quite transparent, and the test-tube, after being rinsed out and filled with water, appears clean. But, if the spirit contains even traces of methylic alcohol, the liquid becomes at first brown, then almost black and opaque, and a film of silver is deposited on the tube, which appears brown by transmitted light. When only 3 to 4 per cent. of methylic alcohol are present, the film is sufficiently thick to form a brilliant metallic mirror. Estimationr qf the'Quantity of Ethyl Nitrite.-One hundred grains of the spirit of nitrous ether are macerated in a little corked flask for 12 hours, with occasional agitation, with 12 to 15 grains of fused potassium hydrate; the ethereal odor will then have disappeared, and the liquid is poured into a beaker, diluted with an equal bulk of water, and left in a warm place until the odor of alcohol has also disappeared. The remaining solution is. then slightly acidulated with diluted sulphuric acid, and tested by delivering into it test solution of potassium permanganate, containing a certain and known quantity of the permanganate.... in each centimetre, or volume- _ ~ __ unit, drop by. drop, and with constant stirring, until the color of the permanganate ceases to be discharged (Fig. 91). FIG. 91. The number of grains and parts of grains of potassium permanoanate required for the test is readily calculated from the volume of- the solution 23 354 MANUAL OF CHEMICAL ANALYSIS. used; and this number, multiplied by 1.18, indicates at once the percentage of ethyl nitrite contained in the spirit. STRYCtHNIA. STRYCIININUM. STRYCHNIUM. Strychnia. Strychnine. Small, brilliant, octahedral crystals, colorless and transparent, or a white, crystalline powder, permanent in the air. Heated upon platinum-foil, strychnia melts, and spreads over the foil like melted resin; it partly volatilizes without decomposition; most of it, however, is decomposed, leaving a charred residue, which, at a stronger heat, is wholly dissipated (evidence of the absence of fixed admixtures). Strvchnia is almost insoluble in. cold water, in absolute alcohol, and in ether, and only sparingly soluble in boiling water, but it dissolves freely in boiling alcohol, in chloroform, and in strong and dilute acids, as also, to some extent, in alcohol containing water; 100 parts of such alcohol, cold, of a spec. grav. of from 0.890 to 0.880, dissolve five parts: of strychnia. The alcoholic solution has a feeble alkaline reaction upon test-paper, and an intensely bitter taste. One grain of strychnia requires for solution about 7 ounces i of boiling, and 16 ounces of cold, water; and these solutions, even when greatly diluted, preserve the intensely bitter taste of strychnia. When a few drops of cold con centrated nitric acid are added, by;G.92. means of a glass rod or a small pipette (Fig. 92), to a little strychnia, or its salts, on a watchglass, it dissolves without any color, or with only a pale STRYCHNIA. 355 greenish or yellow tint (distinction from brucia and morphia, and their salts, which give intensely red solutions). Strong sulphuric acid also dissolves strychnia and its salts without color (distinction from brucia, veratria, and salicin, which yield red or purple reactions); but, when a minute fragment of a crystal, or one drop of a solution of potassium bichromate or permanganate is added, the solution assumes atonce a deep-violet or blue color, which successively changes from violet to red, and finally to green or- yellow. This characteristic reaction* may also be performed upon a porcelain plate, or a glass-pane placed upon white paper, by allowing four drops of concentrated sulphuric acid to fall on the plate, two upon about half a grain of strychrfia each, the third upon a small fragment of potassium bichromate, and the fourth upon a small fragment' of a crystal of potassium permanganate; the drops with the two reagents are then drawn by a glass rod, each to one of thle colorless drops containing the strychnia; the intense coloration will occur at once. When a cold, saturated alcoholic solution of strychnia is mixed with about an equal volume of an alcoholic solution of ammonium sulphydrate, and the mixture is allowed to stand for 12 hours, long, brilliant, orange-red needles are fbrmed, which are insoluble in water, alcohol, ether, and carbon bisulphide, but which are decolorized and decomposed when treated with concentrated sulphuric acid, with the formation of strechnia sulphate, and of an oily compound, which, in contact with water, is resolved into sulphur and hydrosulphuric acid. Strychnia only is known to render this reaction. When a-bout two grains of strychnia are agitated with five fluid-drachms of warm water, they will not wholly dissolve, but will do so at once upon the addition of a few drops of diluted sulphuric acid; this solution, when tested in separate portions, will yield precipitates with tannic acid, with potassio-mercuric iodide, and with iodinized potassium iodide; it will remain unaltered with potassium bicarbonate (distinction fromn the cinchona alkaloids), but it will yield a white precipitate with the * Only aniline and its salts are known to render, with the same reagent, a similar reaction, which, however, is less of a violet, and more of a blue tint throughout, and which does not appear immediately. 356 MANUAL OF CHEMICAL ANALYSIS. alkaline hydrates, insoluble in an excess of the precipitant (further distinction from morphia), and also insoluble when agitated with ether, but soluble in chloroform. Examination: Incidental or fraudulent admixtures of other alkaloids are recognized by the above-described characteristics and reactions of strychnia. Brucia and salicin are indicated by a red coloration with either concentrated nitric or sulphuric acid. Brucia may also be recognized by its ready solubility in absolute alcohol (wherein strychnia is almost insoluble), and by the reaction of its solution in strong nitric acid with stannous chloride or sodium hyposulphite. While pure strychnia renders a pale-green or yellowish solution with strong nitric acid, this will appear more or less red, if brucia be present, and will assume, upon the addition of solution of stannous chloride or of sodium hyposulphite, a deep violet color, which will not disappear upon dilution with water; if the latter reagent has been employed, a white turbidity from the separation of sulphur will occur after a while. Santonin is known by its insolubility in dilute acids, and by its property of becoming lemon-yellow when the sample, covered with a sheet of thin white paper, is exposed to solar light for one or two days. Cinchona alkaloids may be detected by a white precipitate, when a solution of two grains of the strychnia in two drachms of water and three drops of diluted sulphuric acid is tested with solution of potassium bicarbonate. Cincondia may also be recognized by its insolubility in chloroform, remaining behind when a little powdered strychnia is exhausted with that solvent; its identity may then be ascer. rained by its properties, described on page 182. STRYCHNIA. 357 STRYCHNIE NITRAS. STRYCHNINUM SEU STRYCHNIUM NITRICUM. Nitrate of Strychnia or Strychnine. Strychnia Nitrate. Colorless, transparent, flexible needles of a silky lustre; when heated upon platinum-foil, they become slightly yellow, melt, and are finally wholly dissipated (evidence of the absence of fixed admixtures). Strychnia nitrate is soluble in 60 parts of cold, and in three parts of boiling, water; it is also soluble in dilute alcohol and in chloroform, but only sparingly in strong alcohol, and almost insoluble in absolute alcohol, and in ether. Its solutions are neutral, and have an intensely bitter taste. Strychnia nitrate answers to all the reactions of strychnia, and may be recognized by the characteristic coloration with strong sulphuric acid and potassium bichromate or permanganate, as described on page 355. The evidence of being a nitrate may readily be obtained by decolorization, when its solution is faintly blued with sulphuric-acid indigo-solution, and heated, or by dissolving a few grains of the salt, and an equal quantity.'A FiG. 93. of ferrous sulphate, in a little diluted sulphuric acid, and placing the colorless solution upon concentrated sulphuric acid (Fig. 358 MANUAL OF CHEMICAL ANALYSIS. 93); a dark-brown coloration will take place at the junction of the two liquids. The methods for testing the purity of strychnia nitrate are the same as described with strychnia, on pages 355, 356. It needs only to be added that the salt should not emit ammoniacal odors, when heated with liquor potassse, nor cause the rise of white vapors, when a glass rod, moistened with acetic acid, is held over the orifice of the test-tube. STRYCHNIME SULPHAS. STRYCHININUM SEU STRYCHNIUM SULPHURICUM. Sulphate of Strychnic or Strychnine. Strychnia Sulphate. Fine, colorless, and transparent prismatic crystals, containing seven molecules (nearly 14 per cent.) of water of crystallization; slightly efflorescent on exposure to the air; when heated, they melt, and lose the water of crystallization; at a strong heat, they burn away without residue (evidence of the absence of fixed admixtures).,Strychnia sulphate is soluble in 42 parts of cold, and in about two parts of boiling, water; it also dissolves, in nearly the same proportions, in dilute alcohol, but only sparingly in strong alcohol, and is almost insoluble in absolute alcolol and in ether. Its solutions are intensely bitter; their deportment with reagents answers to that of stlmychnia, and they also render the characteristic reaction with sulphuric acid and potassiumn bichromate or permanganate; the evidence of being a sulphate may be obtained by the white precipitate which barium nitrate yields with a solution of strychnia sulphate in dilute nitric acid. When heated with liquor potassse, the salt should not emit ammlloniacal odors, nor should it cause the rise of white vapors when a glass rod, moistened with acetic acid, is held over the orifice of the test-tube. The purity of the salt may be ascertained by the same tests as described with pure strychnia, on pages 355, 356. SULPHUR. 359 SULPHUR PRIECIPITATUIMY. LAC SULPHURIS. Precipitated Sulphur. A fine, slightly coherent powder, of a pale yellowish or grayish color, without taste or smell, and free from grittiness, consisting, when seen under the microscope, of minute, opaque globules, without any admixture of crystalline matter. When thrown upon burning coal, or heated in an open vessel, precipitated sulphur'first emits a little hydrosulphuric-acid gas, then fuses and burns wholly away at a stronger heat. Precipitated sulphur is insoluble in the common solvents, but is dissolved readily and wholly in carbon bisulphide, and in strong, boiling solutions of potassium and sodium hydrates, and also more or less in benzol, in hot oil of turpentine, and other essential and fatty oils. Examination: Fixel acdmixtures are indicated by a white ash left behind upon complete dissipation of about 10 grains of the sulphur in an open porcelain crucible. Calciumr SWudpiate.-About one drachm of the sulphur is triturated with about 6 fluid-drachms of tepid water, and the mixture agitated for a few minutes until cold, when it is filtered; the filtrate must not act upon test-paper, as an acid reaction would indicate long exposure to the air; nor must it leave any residue upon evaporation upon a watch-glass, which would indicate either insufficient washing, or an admixture of a soluble fixed compound; a white precipitate of the filtrate, when tested with amlonium oxalate in one portion, and with a few drops of nitric acid and barium nitrate in another portion, would indicate calcium sulphate. Earthy Carbonates or Pho2p9hates. - When. the sulphur leaves a residue on incineration, or on solution in carbon bisulphide, about 20 grains of the sulphur are digested for several hours, with occasional agitation, with about 3 fluid-drachms of a mixture consisting of equal parts of concentrated hydrochloric acid and water; effervescence upon the addition of the acid would indicate the presence of carbonates. The mixture is 360 MANUAL OF CHEMICAL ANALYSIS. then filtered, and one portion of the filtrate over-saturated with sodium carbonate; an ensuing white precipitate would indicate the presence of the above admixtures; the other portion is tested with ammonium molybdenate, a yellow coloration of the liquid, and after a while a yellow crystalline deposit, would indicate phosphates (if the sulphur be free trom arsenic). Any admixture, except powdered resin or p2itch, which are recognized by a sooty flame when ignited, and by their solubility in strong alcohol or ether, may be quantitatively determined by remaining behind upon solution of a known quantity of the sulphur in carbon bisulphide, or, when calcium sulphate is the only admixture, by complete incineration of a weighed quantity of the sulphur in a tared porcelain crucible; the weight of the remaining anhydrous calcium sulphate, with onefourth thereof added to make up for the loss of the water of crystallization, gives the amount of crystalline calcium sulphate present in the quantity of sulphur under examination. Arsenic may be detected by triturating and digesting about 30 grains of the sulphur with half an ounce of solution of ammonium sesqui-carbonate, or aqua ammonime, in a corked testtube, for about one hour, with occasional agitation; the liquid is then passed through a filter, and a portion of the filtrate overFIG. 94. saturated with hydrochloric acid; the formation of a yellow precipitate would indicate arsenic; the rest of the filtrate is SULPHUR. 361 evaporated to dryness in a small porcelain capsule; if a residue remains, it is scraped off by triturating it with a few grains of powdered mragnesite, or purnice-stone; a few grains of potassium cyanide are added, and the mixture gently warmed so as to expel moisture; it is then introduced into a reduction-tube and heated (Fig. 94); whereupon, the formation of a metallic mirror and the evolution of a garlic-like odor would further indicate arsenic. An admixture of starch may be recognized by examination of the precipitated sulphur under the microscope, or by boiling about 10 grains of it with 2 fluid-drachms of water, and testing the liquid with one drop of iodinized potassium iodide. The occurrence of a blue coloration would show such an adulteration. SULPHUR SUBLIMATUX. FLORES SULPHURIS. Sublimed Sulphur. A gritty, yellow, tasteless, and odorless powder, consisting, when seen under the microscope, of a mixture of minute, smooth globules, and of rhombic-octahedral crystals. When heated in a dry tube, sulphur fuses at about 112~ C., forming an amber-colored fluid, which, when heated to 240~ C., becomes more and more thick and tenacious, until, beyond 260~ C., it becomes thin and liquid again, and boils at 4200 C., volatilizing in colorless vapors, which condense on cooling; when heated with free access of air, sulphur takes fire at about 270~ C., and slowly bulns away with a pale-blue flame, forming sulphurousacid gas. Sublimed sulphur is insoluble in water, and ahnost insoluble in alcohol and in ether; it dissolves to some extent in chloroform, and for the most part in carbon bisulphide,* in benzol, * Both the amorphous (spec. grav. 1.95) and the prismatic (spec. grav. 1.982, fusing-point 120~ C.) modifications of sulphur are almost insoluble in carbon bisulphide, while the octahedral form (spec. grav. 2.045, fusing-point 115~ C.) is readily soluble therein. Both the former varieties pass into the octahedral form, 362 MANUAL OF CHEMICAL ANALYSIS. and in warm or boiling essential and fatty oils; it is wholly soluble in warm liquor potassoe or sodoe. Commercial sublimed sulphur has generally an acid reaction upon moist test-paper, and contains traces of oxygen acids of sulphur, occasionally also of selenium, and frequently of sulphides of arsenic, all which impurities have to be eliminated from such sulphur as is intended for medicinal use (SUL-PHUR LOTUM, SULPHUR DEPURATUIVI); this is done by digesting the crude sublimed sulphur for a few days with very dilute aqua ammonie, or with a solution of amrmonium sesqui-carbonate, and by subsequent thorough washing with water, and drying. Examination: Washed sulphur should not redden moist blue litmus-paper, nor affect the color of water which has been slightly blued with litmus-tincture, when agitated with a little of the sulphur. Warml water, when rubbed with the sulphur in a mortar, should render a filtrate which leaves no residue on evaporation on platinum-foil or on a watch-glass. Minieral and fixecd acldmixtres are recognized by remaining behind, either upon complete dissipation of the sulplhur in a porcelain crucible, or upon solution of about 20 grains of the sulphur in a strong boiling solution of potassium or sodium hydrate. Ar.senic may be detected by digesting the sublimed sulphur for several hours, with about four times its weillht of a dilute solution of ammonium sesqui-carbonate. This dissolves only the arsenic sulphides; they may be recognized by a yellow precipitate, either at once or after a while, when a portion of the filtrate is over-saturated with hyldrochloric acid, and by a yellow residue upon evaporation of the filtrate on a water-bath, and also by the formation of a metallic mirror when this residue is heated in a dry reducing-tube with potassium cyanide (Fig. 94, page 360). Selenuzu,7n may be detected by heating to boiling a mixture slowly at ordinary temperatures, and more rapidly at higher ones. Therefore, the older sublimed sulphur is, the more soluble it is in carbon bisulphide. There are, however, minor varieties of both the amorphous and the crystalline modifications of sulphur, which appear to differ in their deportment with solvents, and thereby also to alter the solubility of sublimed sulphur in carbon bisulphide. SULPHUR. 363 consisting of about one drachm of the sulphur, and a solution of half a drachm of potassium cyanide in one ounce of water; when cool, this mixture is filtered, and the filtrate over saturated with concentrated hydrochloric acid-taking care not to inhale the vapors of the evolved hydrocyanic'acid; the solution is allowed to stand in a corked vial for about 24 hours. A reddish turbidity or deposit would indicate selenium. If the sulphur contains arsenic sulphides, they will give rise to the simultaneous formation of a yellow precipitate, which, however, will appear more or less reddish in hue when selenium is contained in the sulphur. SULPHURIS IODIDUM. SULPHUR IODIDUM. SULPHUR IODATUM. Iodide of Sulphur. Sulphur Iodide. Grayish-black, flat plates, or fragments of plates, of a radiated, crystalline fracture, and the odor of iodine. Sulphur iodide is an unstable compound, and is readily decomposed; on exposure to the air, iodine evaporates gradually; it is also decomposed by boiling water, and, when heated in the air, the iodine passes off in vapor, and is wholly expelled, leaving behlind sulphur, which burns away at a strong heat with a pale blue flame. Sulphur iodide is insoluble in water, but this takes up a trace of iodine; it is soluble in about 60 parts of glycerin; alcohol, as well as strong solutions of potassium iodide, or of potassium hydrate, deprives it completely of the iodine, leaving the sulphur behind; in this way, sulphur iodide may be examined by exhausting 50 grains of it with alcohol; only 10 grains of sulphur should remain behind, and, when this is divided into two portions, one of them should burn away at a strong heat, with the odor of sulphurous acid, and the other must be completely soluble in carbon bisulphide. 364 MANUAL OF CHEMICAL ANALYSIS. VERATRIA. VERATRINUM. VERATRIUM. Veratria. Veractrine. A white or grayish-white coherent powder, or minute, efflorescent prismatic crystals, without smell, but exciting violent sneezing when admitted into the nostrils. Heated upon platinum-foil, veratria fuses into a yellow liquid, which, on cooling, solidifies to a transparent yellowish mass; at a stronger heat, it is-charred, and burns wholly away. Veratria is soluble in three parts of cold alcohol, and freely in acids, in ether, and in chloroform, less so in amylic alcohol, and only sparingly in cold, as well as in boiling, water, but readily upon the addition of acids. The solution in diluted acids has a persistent acrid, though not bitter, taste, causing a sensation of tingling, with numbness of the tongue. It has an alkaline reaction, and gives a white precipitate with'tannic acid and with potassio-mercuric iodide, a brown one with iodinized solution of potassium iodide, and a white one with the alkaline hydrates, insoluble in an excess of the precipitant, but soluble in alcohol, ether, and chloroform; when concentrated sulphuric acid is added to the solution of veratria, so that heat is evolved, it assumes a purple coloration; concentrated hydrochloric acid produces the same color, though less intense, and not without heating the mixture. Concentrated sulphuric acid dissolves veratria, with a yellow color, which successively becomes orange, purple, and deep red or violet; gentle heat accelerates this reaction; concentrated hydrochloric acid dissolves veratria without color; the solution becomes purple, however, upon heating. Concentrated nitric acid does not effect any coloration with veratria; nor does concentrated sulphuric acid, when diluted with one-third its bulk of water, produce any coloration, unless heated. Examination: Minteral or other inrsoluble admixtures may be readily detected by their insolubility in chloroform and in alcohol. Bruzcia remains behind upon solution in ether;* it may * The solubility of commercial veratria in ether varies, some kinds being less readily soluble, and the crystalline more so than the amorphous. ZINCUM. 365 also be confirmed or recognized by dissolving a little of the veratria in some concentrated nitric acid, diluted with an equal part of water; veratria yields a colorless solution, whichll, however, will appear red when brucia is present; the red solution gives way to a yellow color upon heating the test-tube by dipping it in boiling water; this yellow, however, will turn deep violet upon the addition of a few grains of stannous chloride or sodium hyposulphite. NonQ of these color-reactions will take place with pure veratria. ZINCI ACETAS. ZINCUM ACETICUM. Acetate of Zinc. Zinc Acetate. Colorless, translucent plates, or lamellar, rhombic prisms, of a pearly, unctuous lustre, flexible, and with a faint odor of acetic acid, which is freely evolved when the crystals are treated with sulphuric acid; they contain three molecules (22.88 per cent.) of water of crystallization, and are ordinarily permanent in the air, but efflorescent in air that is dry and warm. When heated upon charcoal, before the blow-pipe, zinc acetate undergoes aqueous fusion, solidifies again, after the evaporation of the water of crystallization, and emits vapors of acetic acid, and the products of the decomposition of the latter; finally zinc oxide is left behind, yellow while hot, white when cold. When this residue is moistened with one drop of solution of cobaltous nitrate, and heated to redness, it will appear green, after cooling. Zinc acetate dissolves in 3 parts of cold, and in 1-1 part of boiling, water, and in 30 parts of cold, and about 3 parts of boiling, alcohol; the aqueous solution has an astringent, inetallic taste, and a slightly acid reaction, and gives only a white turbidity or an incomplete precipitation with lhydrosulphuric acid, but a complete one with ammonium sulphydrate; it forms white precipitates with the alkaline hydrates and carbonates, of which those with the hydrates, and with ammonium carbon 366 MANUAL OF CHEMICAL ANALYSIS ate, are redissolved by an excess of the precipitant, but these solutions are precipitated again, by boiling, if not too concentrated. Solution of zinc acetate acquires a red color, upon the addition of a few drops of dilute solution of a ferric salt. Examination: ]ifetallic and earthy im7purities are indicated by a precipitate, when the aqueous solution, after acidulation with acetic acid, is mixed with an equal volume of hydrosulphuric acid, and allowed to stand for a few hours, and by a not quite white precipitate when this liquid is afterward slightly over-saturated with ammonium hydrate. [fagnesiumv salts may also be recognized, in the solution of zinc acetate, by mixing the latter with so much ammnonium sesqui-carbonate as is required to redissolve the precipitate formed at first; one or two drops of phosphoric acid are then added, and will cause a white precipitate, if magnesia be present. Alkaline salts may be recognized by a strong alkaline reaction, when about 10 grains of the salt are completely reduced upon charcoal, before the blow-pipe, and the residue tested with moist blue litmus-paper. ZINCI CHLORIDUM. ZINCUM CHLORATUM. ZINCUM MURIATICUEM. Chloride of Zinc. Zinc Chloride. A colorless, coherent, granular powder, or colorless, opaque, fused rods or fragments of tablets, very deliquescent and caustic. When heated upon charcoal or platinum-foil, zinc chloride fuses at about 225~ C., and volatilizes, emitting thick, white vapors, and leaving behind a slight coating, yellow when hot, white when cold. Zinc chloride is soluble in water, glycerin, alcohol, and ether, giving more or less turbid, and slightly acid, solutions, ZINCUM. 367 which, however, become clear upon the addition of hydrochloric acid; the aqueous solution is precipitated by the alkaline hydrates and carbonates, forming white precipitates, which, with the exception of those with potassium or sodium carbonate, are soluble in an excess of the precipitant; these last solutions may be reprecipitated either by hydrosulphuric acid or by boiling. The solution of zinc chloride, acidulated with nitric acid, yields, when diluted with water, a curdy white precipitate with argentic nitrate, soluble in aqua ammoniae, and it occasions white precipitates with liquids containing albumen or gluten. Examination: Scalts.-About 10 grains of the zinc chloride are dissolved in 10 drops of water and two drops of concentrated hydrocllloric acid; part of this solution is dropped into strong alcohol; an ensuing turbidity, or the separation of a granular salt, would indicate the admixture of salts insoluble or less soluble in alcohol. aaclccitnm chloride may be detected in the rest of the solution obtained in the preceding test, by precipitating it with ammonium sesqui-carbonate, and by subsequently redissolving the precipitate by the addition of an excess of the reagent; an incomplete solution would indicate calcium chloride. Suliphate may be recognized by a white precipitate in the diluted solution, acidulated with hydrochloric acid, on testing with barium chloride. ifragneszium and manganese chlorides may be detected, in the ammoniacal solution of the preceding test, after filtering, if necessary, by testing it with a few drops of solution of sodium phosphate; the occurrence of a turbidity, not disappearing upon the addition of solution of ammonium sesqui-carbonate, would indicate magnesium salts, if the precipitate is white, and manganese salts, if it has a pale reddish color, Ammoniutn chloride (ammonio-zinc chloride) may be detected by an amnmoniacal odor, and by white vapors when a glass rod, moistened with acetic acid, is held in the orifice of the test-tube, wherein a few grains of the salt are heated with a strong solution of potassium hydrate. Mletallic impunrities are detected by mixing a strong solu 368 MANUAL OF CHEMICAL ANALYSIS. tion of the salt, rendered limpid by a few drops of hydrochloric acid, with twice its volume of hydrosulphuric acid; a white turbidity will occur, which must disappear upon further acidulation with hydrochloric acid, and warming; a colored precipitate would indicate metallic impurities (lead, copper, or cadmium). If a yellow precipitate takes place, drsenic is indicated, The presence of this substance may be confirmed by the occurrence of a brown precipitate, when a solution of about 10 grains of the zinc chloride in half an ounce of concentrated hydrochloric acid is heated to boiling with about 20 drops of concentrated solution of stannous chloride. ZINCI OXIDUX. ZINCUM OXYDATUM. FLORES ZINCI. Oxide of Zinc. Zinc Oxide. A white powder, soft and loose, inodorous and tasteless, remaining white when mixed with hydrosulphuric acid. When heated in a dry tube or a porcelain crucible, it neither fuses nor volatilizes, but assumes a lemon-yellow color, which disappears again on cooling; when the oxide is subsequently heated in a lixture of equal parts of acetic acid and water, it dissolves wholly and without effervescence. When moistened with one drop of solution of cobaltous nitrate, and heated in the flame of the blow-pipe, zinc oxide assumes a green color. Zinc oxide is insoluble in water, glycerin, and alcohol, but soluble in diluted acids, forming colorless solutions, which, when acid, are not acted upon by hydrosulphuric acid or ammoniumn sulphydrate; when neutral, they are only incompletely precipitated by the former reagent, but completely by the latter; when alkaline, they are wholly precipitated by both reagents. The solutions of zinc oxide form white precipitates with the alkaline hydrates and carbonates, of which those with the former, and with ammonium carbonate, are soluble in an ex ZINCUM. 369 cess of the precipitant, but they are reprecipitated from these solutions, if not too concentrated, by boiling. Zinc oxide is, therefore, soluble in concentrated solutions of the alkaline hydrates (when free from carbonates), and of ammonium carbonate. Zinc oxide absorbs carbonic acid slowly from the atmosphere. Examination: Sulphates and Chlorides. —About one drachm of the zinc oxide is agitated for a few minutes with about one ounce of boiling water, and subsequently filtered; a few drops of the filtrate, evaporated upon platinum-foil, should l]eave no residue; nor should the filtrate, after the addition of a few drops of nitric acid, give any reaction with barium nitrate or with argentic nitrate. Carbonates and Salts of Aluminium, and Alkaline Earthy Sullphates and Phosphates.-The oxide left on the filter in the preceding test is dissolved, with the aid of heat, in about half a fluidounce of acetic acid diluted with an equal volume of water; effervescence would indicate carbonates, and an insoluble residue, aluminium salts or calcium or barium snlphates (zinc oxide prepared in the dry way generally leaves a small gray residue, consisting of minute particles of metallic zinc, readily soluble in hydrochloric or nitric acid); the solution is filtered, if necessary, and is then slowly over-saturated with aqua ammoniae; the ensuing white turbidity must disappear upon the addition of an excess of the reagent; a remaining turbidity would indicate earthy phosphates. Calcium and iXagnesium.-The ammoniacal solution of the preceding -test is filtered, if necessary, and is tested in separate portions with ammonium oxalate for calcium, and with a few drops of diluted phosphoric acid for magnesium; a white turbidity, not disappearing upon addition of aqua ammnoniae, will indicate calcium with the first and magnesium with the latter reagent. Arsenic and Cadmium.-The rest of the ammoniacal solution is mixed with twice its volume of hydrosulphuric acid; a white precipitate should occur, which disappears upon oversaturation with hydrochloric acid and gentle warming; a slight 24 37-0 MANUAL OF CHEMICAL ANALYSIS. remaining precipitate, yellow or pale brown, would indicate arsenic or cadmium. If such a reaction takes place, so much of the precipitate may be obtained as to collect it upon a small filter; it is washed with a little hydrosulphuric acid, and subsequently with water, and is then treated upon the filter with a few drops of a warm strong solution of ammonium. sesqui-Qarboilate; arsenic sulphide is dissolved, and may be reprecipitated in the solution by over-saturating it with hydrochloric acid diluted with some hydrosulphuric acid. Cadmium sulphide remains undissolved upon the filter, and may, be recognized by a red-brown coating of the coal, when heated with a little exsiccated sodium carbonate upon charcoal before the blow-pipe (Fig. 95). FIG. 95. As a confirmatory test for arsenic, or to detect a minute quantity of it, about 10 grains of the oxide may be dissolved in half an ounce of concentrated hydrochloric acid, and, after the addition of 20 drops of concentrated solution of stannous chloride, heated to boiling; a brown turbidity would confirm the presence of arsenic. ZINCI SULPfAS. ZINCUM SULPHURICUM. Sulphate of Zinc. White Vitriol. Zinc Sulphate. Colorless, transparent rhombic prisms, containing 7 molecules (43.89 per cent.) of water of crystallization, of which 6 ZINCUM. 371 molecules evaporate at common temperature in dry air, with efflorescence of the salt, while the remaining one does not separate below 220~ C. When heated, zinc sulphate undergoes aqueous fusion, and becomes solid again after the evaporation of the water; at a stronger heat, it is. decomposed, sulphurous acid and oxygen being evolved, and zinc oxide remaining behind; when this is moistened with one drop of solution of cobaltous nitrate, and heated again to redness, it assumes a green color (magnesium'sulphate, when similarly treated, gives a reddish coloration, alum a blue one). Zinc sulphate is readily soluble in water, 100 parts of which dissolve at 10~ C. 138 parts, at 20~ C. 161.5 parts, and at 1000 C. 653.5 parts, of the crystallized salt; it is soluble in about three parts of glycerin, and in an excess of the solutions of the alkaline hydrates, but it is little soluble in strong, and not at all in absolute, alcohol; the aqueous solution reddens blue litmus-paper and has a metallic styptic taste, remains colorless with solution of tannic acid, and gives, a copious white precipitate with highly diluted solution of barium chloride. Its deportment with reagents is the same as described on page 368. Examination: Metallic Impur'ities.-A concentrated solution of zinc sulphate is slightly acidulated with a few drops of diluted sulphuric acid, and added to about three times its volume of hydrosulphuric acid; no turbidity or coloration should take place; aqua ammonim is then added in a slight excess, and must produce a perfectly white precipitate; or otherwise metallic impurities (copper, lead, cadmium, iron, arsenic) are indicated. The same test may serve to distinguish at once magnesium sulphate from zinc sulphate; these substances, being isomorphous and of a similar appearance, are liable to -be taken one for the other; solution of magnesium sulplhate is not acted upon by hydrosulpburic acid, nor by amnmonium sulphydrate. Alkaline and Earthy Suplpates.-A solution of 20 grains of zinc sulphate in about 3 drachms of water is mixed with a solution of 30 grains of crystallized plumbic acetate in half an ounce of water; after repeated agitation, the mixture is fil 372 MANUAL OF JCHEMICAL ANALYSIS. tered, and tthe filtrate completely precipitated with hydrosulphuric acid; this mixture is also filtered, and the filtrate must leave no residue upon evaporation on platinum-foil; if any such remains, the presence of alkaline or earthy sulphates is indicated. JMagnesium and aluminium sulpyhates are indicated by a white insoluble residue, when the solution of the salt is precipitated by ammonium hydrate, and the precipitate redissolved in an excess of the precipitant. ZINCI VALERIANAS. ZINCUM VALERIANICUM. Valerianate of Zinc. Zinc Valerianate. Anhydrous, white, pearly lamellar crystals,* somewhat unctuous to the touch, and with a feeble odor of valerianic acid. When heated, they fuse at 140~ 0., and decompose at a higher temperature, with the evolution of white, inflammable vapors, finally leaving behind zinc oxide (about 30 per cent.), which, when moistened with a drop of a solution of cobaltous nitrate, and reheated to redness, becomes green. Zinc valerianate dissolves in 90 parts of cold, and 40 parts of boiling, water, and in 60 parts of cold, and 17 parts of boiling, alcohol, of a spec. grav. of 0.835; it is also soluble in glycerin, and in an excess of aqua ammonioe,.but only sparingly in ether or chloroform. Its solutions redden blue litmus-paper, and become turbid upon warming, but clear again on cooling; it is also readily soluble in diluted acids, but with decomposition, and consequent turbidity from the elimination of the valerianic acid, which gradually collects as an oily stratum upon * Sometimes a hydrated zinc valerianate is met with, obtained by mixing equivalent quantities of valerianic-acid hydrate and freshly-precipitated zinc carbonate, with a small amount of water, so as to form a paste, and by subsequent exsiccation at a gentle heat; it forms a whitish powder, and has the same properties and reactions as the crystallized anhydrous salt, except that it contains 44 per cent. of water, and is more soluble in water, glycerin, and alcohol; from its solution, the anhydrous salt crystallizes. ZINCUM. 373 the aqueous solution; an addition of aqua ammonioa at first increases the turbidity, but, when added in excess, fobrms a clear solution. The deportment of solutions of zinc valerianate with reagents, after the elimination of the acid by hydrochloric or sulphuric acids, is the same as described on page 368. Examination: Zinc acetate may be detected by agitating a little of the triturated zinc valerianate, in a test-tube, with about two drachms of cold water, and adding to the filtrate one or two drops of ferric chloride; the liquid, if necessary, is filtered again, and must appear almost colorless; a reddish tint would indicate. acetic acid. Tcartaric and Oxalic Acids, and ilagnesizum and Calciumn. -The undissolved valerianate of the preceding test is rinsed through the broken filter into a test-tube, and is agitated with a sufficient quantity of aqua ammonim; a complete solution must take place, which may be tested, in separate portions, with solution of calcium chloride for oxalic and tartaric acids, and with solution of sodium phosphate for calcium and magnesium FIG. 96. salts; a white precipitate, in either case, will indicate one or other of the above admixtures. Boracic acid may be detected by triturating a little of the salt with a few drops of alcohol, and by igniting and burning 374 MANUAL OF CHEMICAL ANALYSIS. the mixture, with stirring: a green coloration of the flame, especially toward the termination of the ignition, would indicate boracic acid. Butyric Acid.-About one drachm of the salt is triturated, and added, in a small flask, to a mixture consisting of 100 grains of concentrated sulphuric acid and 100 grains of water; the mixture is submitted to distillation at a gentle heat (Fig. 96), until about half a drachm of distillate is obtained; this is agitated with a little concentrated solution of cupric acetate, which should not immediately affect the transparency of the liquid, but it forms, after a while, oily drops of anhydrous cupric valerianatej which, after from 5 to 20 minutes, pass into a greenish-blue crystalline deposit of hydrated cupric valerianate. If. however, the salt consists mainly or wholly of butyrate, the transparency of the liquid would at once be impaired by tile formation of a crystalline precipitate. TABLES AND INDEX. TABLES. 377 T ABLE I OF ELEMENTARY BODIES, WITH THEIR ATOMIC SYMBOLS AND'WEIGHTS. Atomic Atomic NAME. NAME. Symbol. Weight. Symbol. Weight. Hydrogen (Standard unity), H 1 Lead, Pb 207 Aluminium, Al 27.4 Lithium, Li 7 Antimony, Sb 122 Magnesium, Mg 24 Arsenic, As 75 Manganese, Mn 55 Barium, Ba 137 Mercury, Hg 200 Bismuth, Bi 210 Molybdenum, Mo 96 Boron, Bo 11 Nickel, Ni 58.8 Bromine, Br 80 Nitrogen, N 14 Cadmium, Cd 112 Oxygen, 0 16 Calcium, Ca 40 Phosphorus, P 31 Carbon, C 12 Platinum,. Pt 197.4 Cerium, Ce 92 Potassium, K 39.1 Chlorine, C1 35.5 Selenium, Se 79.4 Chromium, Cr 52.2 Silicon, Si 28 Cobalt, Co 58.8 Pilver, Ag 108 Copper, Cu 63.4 Sodium, Na 23 Fluorine, F [ 9 Strontium, Sr 87.6 Gold, Au 197 Sulphur, S 32 Iodine, I 127 Tin, Sn 118 Iron, Fe 56 Zinc, Zn 65.2 378 TABLES. T ABL II E FOR CONVERTING DEGREES OF THE CENTIGRADE THERMOMETER INTO DEGREES OF FAHRENHEIT'S SCALE. Cent. Fahr. Cent. Fahr. Cent. Fahr. Cent. Fahr. -40 -40.0 +1 +33.8 +42 +107.6 + 83 +181.4 -39 — 38.2 2 35.6 43 109.4 84 183.2 — 38 — 36.4 3 37.4 44 111.2 85 185.0 - 37 -34.6 4 39.2 45 113.0 86 186.8 - 36 -32.8 5 41.0 46 114.8 87 188.6 -35 -31.0 6 42.8 47 116.6 88 190.4 -34 -29.2 7 44.6 48 118.4 89 192.2 - 33 -27.4 8 46.4 49 120.2 90 194.0 -32 -25.6 9 48.2 50 122.0 91 195.8 - 31 -23.8 10 50.0 51 123.8 92 197.6 -30 -22.0 11 51.8 52 125.6 93 199.4 -29 -20.2 12 53.6 53 127.4 94 201.2 28 -18.4 13 55.4 54 129.2 95 203.0 -27 -16.6 14 57.2 55 131.0 96 204.8 - 26 -14.8 15 59.0 56 132.8 97 206.6 -25 -13.0 16 60.8 57 134.6 98 208.4 -24 - 11.2 17 62.6 58 136.4 99 210.2 -23 - 9.4 18 64.4 59 138.2 100 212.0 22 - 7.6 19 66.2 60 140.0 101 213.8 - 21 - 5.8 20 68.0.61 141.8 102 215.6 -20 - 4.0 21 69.8 62 143.6 103 217.4 — 19 - 2.2 22 71.6 63 145.4 104 219.2 - 18 0.4 23 73.4 64 147.2 105 221.0 17 + 1.4 24 75.2 65 149.0 106 222.8 - 16 3.2 25 77.0 66 150.8 107 224.6 15 5.0 26 78.8 67 152.6 108 226.4 -14 6.8 27 80.6 68 154.4 109 228.2 13 8.6 28 82.4 69 156.2 110 230.0 12 10.4 29 84.2 70 158.0 111 231.8 - 11 12.2 30 86.0 71 159.8 112 233.6 10 14.0 31 87.8 72 161.6 113 235.4 - 9 15.8 32 89.6 73 163.4 114 237.2 -8 17.6 33 91.4 74 165.1 115 239.0 - 7 19.4 34 93.2 75 167.0 116 240.8 6 21.2 35 95.0 76 168.8 117 242.6 - 5 23.0 36 96.8 77 170.6 118 244.4 4 24.8 37 98.6 78 172.4 119 246.2 - 3 26.6 38 100.4 79 174.2 120 248.0 2 28.4 39 102.2 80 176.0 121 249.8 - 1 30.2 40 104.0 81 177.8 122 251.6 - 0 32.0 41 105.8 82 179.6 123 253.4 TABLES. 379 Cent. Fahr. Cent. Fahr. Cent. Fahr. Cent. Fahr. +124 +255.2 +176 - 348.8 +228 +442.4 +280 +536.0 125 257.0 177 350.6 229 444.2 281 537.8 126 258.8 178 352.4 230 446.0 282 539.6 127 260.6 179 354.2 231 447.8 283 541.4 128 262.4 180 356.0 232 449.6 284 543.2 129 264.2 181 357.8 233 451.4 285 545.0 130 266.0 182 359.6 234 453.2 286 546.8 131 267.8 183 361.4 235 455.0 287 548.6 132 269.6 184 363.2 236 456.8 288 550.4 133 271.4 185 365.0 237 458.6 289 552.2 134 273.2 186 366.8 238 460.4 290 554.0 135 275.0 187 368.6 239 462.2 291 555.8 136 276.8 188 370.4 240 464.0 292 557.6 137 278.6 189 372.2 241 465.8 293 559.4 138 280.4 190 374.0 242 467.6 294 561.2 139 282.2 191 375.8 243 469.4 295 563.0 140 284.0 192 377.6 244 471.2 296 564.8 141 285.8 193 379.4 245 473.0 297 566.6 142 287.6- 194 381.2 246 474.8 298 568.4 143 289.4 195 383.0 247 476.6 299 570.2 144 291.2 196 384.8 248 478.4 300 572.0 145 293.0 197 386.6 249 480.2 301 573.8 146 294.8 198 388.4 250 482.0 302 575.6 147 296.6 199 390.2 251 483.8 303 577.4 148 298.4 200 392.0 252 485.6 304 579.2 149 300.2 201 393.8 253 487.4 305 581.0 150 302.0 202 395.6 254 489.2 306 582.8 151 303.8 203 397.4 255 491.0 307 584.6 152 305.6 204 399.2 256 492.8 308 586.4 153 307.4 205 401.0 257 494.6 309 588.2 154 309.2 206 402.8 258 496.4 310 590.0 155 311.0 207 404.6 259 498.2 311 591.8 156 312.8 208 406.4 260 500.0 312 593.6 157 314.6 209 408.2 261 501.8 313 595.4 158 316.4 210 410.0 262 503.6 314 597.2 159 318.2 211 411.8 263 505.4 315 599.0 160 320.0 212 413.6 264 507.2 316 600.8 161 321.8 213 415.4 265 509.0 317 602.6 162 323.6 214 417.2 266 510.8 318 604.4 163 325.4 215 419.0 267 512.6 319 606.2 164 327.2 216 420.8 268 514.4 320 608.0 165 329.0 217 422.6 269 516.2 330 626.0 166 330.8 218 424.4 270 518.0 340 644.0 167 332.6 219 426.2 271 519.8 350 662.0 168 334.4 220 428.0 272 521.6 360 680.0 169 336.2 221 429.8 273 523.4 370 698.0 170 338.0 222 431.6 274 525.2 380 716.0 171 339.8 223 433.4 275 527.0 390 734.0 172 341.6 224 435.2 276 528.8 400 752.0 173 343.4 225 437.0 277 530.6 410 770.0 174 345.2 226 438.8 278 532.4 420 788.0 175 347.0 227 440.6 279 534.2 430 806.0 380 TABLES. TA BLE FOR CONVERTING TROY-WEIGHTS INTO METRIC WEIGHTS. Grammes. Grammes.'i Grammes. Grammes. 1 0.0648 30 1.9438 59 3.8228 88 5.7017 2 0.1295 31 2.0085 60 3.8875 89 5.7664 3 0.1943 32 2.0733 61 3.9523 90 5.8312 4 0.2591 33 2.1381 62 4.0171 91 5.8960 5 0.3239 34 2.2030 63 4.0819 92 5.9609 6 0.3887 35 2.2678 64 4.1467 93 6.0257 7 0.4535 36 2.3325 65 4.2114 94 6.0904 8 0.5183 37 2.3973 66 4.2762 95 6.1552 9 0.5831 38 2.4620 67 4.3410 96 6.2200 10 0.6479 39 2.5269 68 4.4059 97 6.2849 11 0.7128 40 2.5917 69 4.4707 98 6.3497 12 0.7775 41 2.6564 70 4.5354 99 6.4144 13 0.8422 42 2.7212 71 4.6002 100 6.4791 14 0.9070 43 2.7860 72 4.6650 120 7.7750 15 0.9719 44 2.8509 73 4.7299 150 9.7186 16 1.0367 45 2.9157 74 4.7947 180 11.6625 17 1.1014 46 2.9804 75 4.8593 200 12.9583 18 1.1662 47 3.0452 76 4.9241 240 15.5500 19 1.2310 48 3.1100 77 4.9890 300 19.4375 20 1.2959 49 3.1749 78 5.0538 360 23.3250 21 1.3607 50 3.2395 79 5.1185 400 25.9168 22 1.4254 51 3.3043 80 5.1833 480 31.1003 23 1.4902 52 3.3691 81 5.2481 500 32.3960 24 1.5550 53 3.4340 82 5.3130 600 38.8751 25 1.6198 54 3.4988 83 5.3778 700 45.3543 26 1.6845 55 3.5636 84 5.4425 800 51.8335 27 1.7493 56 3.6284 85 5.5073 900 58.3128 28 1.8141 57 3.6931 86 5.5721 960 62.2003 29 1.8790 58 3.7580 87 5.6370 1000 64.7920 TABLES. 381 TAB ILE FOR CONVERTING METRIC WEIGHTS INTO TROY-WEIGHTS. EXACT APPROXIMATE EXACT APPROXIMATE EQUIVALENTS IN EQUIVALENTS IN EQUIVALENTS TROY-WEIGHTS. EQUIVALENTS TROY-WEIGHTS. IN. IN GRAINS. 3 GAINS. - 0.01 0.1543 - _ - - 12.0 185.208 3 - 50.02 0.3086 - _ _ 1 13.0 200.642 -3 1 0.03 0.4630 _- - - 1 14.0 216.076 _ 3 1 16 0.04 0.6173 - - - 15.0 231.510 - 3 2 110.05 0.7717 - - - 3 16.0 246.944 - 4 - 6 0.06 0.9260 - - - 91 17.0 262.378 - 4 1 20.07 1.0803 - - - 1 18.0 277.812 - 4 1 170.08 1.2347 - - - 14 19.0 293.246 - 4 2 131 0.09 1.3890 - - - 11 20.0 308.680 - 5 - 0.1 1.543 - - - 12 21.0 324.114 - 5 1 4aw 0.2 3.086 - - - 3 22.0 339.548 - 5 1 190.3 4.630 - - - 41 23.0 354.982 - 5 2 15 0.4 6.173 - - - 61 24.0 370.416 - 6 - 102 0.5 7.717 - -_ 74 25.0 385.850 - 6 1 54 0.6 9.260 - - - 9 11 26.0 401.284 - 6 2 1lT 0.7 10.803 - - - 103 27.0 416.718 - 6 2 16 70.8 12.347 - - - 12~ 28.0 432.152 - 7 - 121 0.9 13.890 - - 14 29.0 447.586 - 7 1 7 1.0 15.434 - - - 15- 30.0 463.020 - 7 2 3 2.0 30.868 - - 1 1.0-4 31.0 478.454 - 7 2 183.0 46.302 - - 2 6 32.0 493.888 1 - 1314.0 61.736 - 1 - 1 3 40.0 617.360 1 2 - 175.0 77.170 - 1 - 17 45.0 694.530 1 3 1 10o 6.0 92.604 - 1 1 112 50.0 771.701 14 2 11'7.0 108.038 - 1 2 8 60.0 926.041 1 7 1 - 8.0 123.472 - 2 - 3[ 70.0 1080.381 2 2 - 40 9.0 138.906 - 2 - 18-1 80.0 1234.721 2 4 1 1410.0 154.340 - 2 1 144 90.0 1389.062 2 7 - 9 11.0 169.774 - 2 2 94 100.0 1543.402 3 1 2 3T4 IN D EX. (The Latin names are in Italics.) A. Acids, volumetric estimation of.... 61 Acidumr, aceticum................ 69 Acetate of ammonium, solution of.. 245 arsenicosurni................. 73 copper..................... 188 benzoicum.................. 75 iron, solution of............. 247 boracicurn................... 78 lead.................. 2'78 boricum.... 78 morphia................ 271 carbolicum.................. 78 potassium.................. 285 chromicunz.................. 80 sodium........ 329 citricum.................... 80 zinc....................... 365 cqallicum.................... 82 Acetic acid.............. 69 hydrochloricum.............. 83 ether......... 116 hydrocyanicurn............... 88 Aceturnm........................ 67 ydroqqantum.............. 88 plumbicum.............. 251 lacticum.................... 90 Acid, acetic..................... 69 muriaticum................ 83 arsenious................... 73 nitricurn.................. 91 benzoic..................... 75 oxalicumrn.................... 95 boracic................... 78 phenylicum.................. 78 boric..................... 78 phlosphoricum. 9........ 96 carbolic.................... 78 succinicum.................. 102 chromic................... 80 sulphuricum............... 104 citric....................... 80 tannicum................... 109 gallic...................... 82 tartaricurn................ 110 hippuric..................... 76 valerianicu?................ 111 hydrochloric................ 83 Aconitia....................... 113 hydrocyanic................. 88 Aconitinum..................... 113 hydrosulphuric (as reagent).... 22 Aerugo........................ 188 indigo-sulphuric (as reagent)... 21 Aeter..................... 114 lactic.......... 90 aceticus............ 116 muriatic.................... 83 Aethiops nmartialis................ 211 nitric...................... 91 Albumen (as reagent)............. 32 oxalic...................... 95 Alcohol......................... 118 phenylic................... 78 amylic..................... 122 phosphoric................. 96 ethylic..................... 118 succinic.................. 102 phenic...................... 78 sulphuric................... 104 Alcohol amrnylicum................ 122 tannic................... 109 sulphuris................... 173 tartaric...................... 110 Algaroth's powder............... 246 valerianic................ 111 Alkalies, volumetric estimation of.. 58 384 INDEX. Alkaline carbonates, estimation of.. 60:Antimoniate of potassium (as reAlkanet-paper.................. 33 agent)..................... 25 Almonds, oil of bitter............. 274 Antimonic sulphide.............. 140 water of bitter.......... 146 Antimonii et potassii tartras....... 131 Alum................. 122 chloridi, liquor............... 246 iron.................... 202 oxidum.................... 134 Alumen..................... 122 oxy-sulphuretum.............. 136 Aluminii et Ammonii sulphas...... 122 sulphuretum aurantiacum..... 140 et Potassii sulphas........... 122 sulphuretum nigrum........ 138 sulphas.... 124 Antimonious chloride, solution of... 246 Aluminium sulphate............. 124 oxide...................... 134 Aluminium sulphuricum.......... 124 oxy-chloride.............. 246 Amido-chloride of mercury........ 240 oxy-sulphide................ 135 Ammonia, solution of............. 142 sulphide................... 138 Ammoniated cupric sulphate...... 193 Antimonium et potassium tartaricum 131 ferric chloride.............. 201 oxydatum................... 134 magnesium sulphate (as reagent) 26 oxy xsulphuratum..... 135 mercury............... 240 su/phuratum aurantiacum..... 140 pyrophosphate of iron........ 214 sulphuratum nigrum........ 138 Ammonii acetatis, liquor.......... 245 tartaratum........... 131 benzoas..................... 124 Antimony, butter of.............. 246 bromidum................. 125 chloride of.................. 246 carbonas................... 126 oxide of................... 134 chloridum................... 127 oxy-chloride of.............. 246 iodidum... 128 oxy-sulphide of.............. 135 murias.................... 127 pentasulphide of............ 140 nitras................... 129 sulphide of.................. 138 phosphas.................... 130 trisulphide of...... 138 valerialas.................. 131 Aqua ammonice...... 142 Ammonio-chloride of iron......... 201 amygdalarum amararum. 146 -cupric sulphate.......... 193 calcis................... 247 -ferric chloride.............. 201 chlori...................... 147 -ferric citrate.............. 201 chlorinii................... 147 -ferric sulphate............. 202 destillata................... 149 -ferric tartrate.............. 203 Argenti nitras.................. 150 -mercuric chloride........... 240 oxidum................... 154 Ammonium acetate, solution of.... 245 Argentic nitrate................. 150 benzoate.................. 124 volumetric test-solution of.... 62 bromide................... 125 oxide..................... 154 carbonate................. 126 Arseiniate of iron................. 196 chloride............. 127 sodium.................. 330 hydrate, solution of.......... 142 Arsenic, white.................. 73 iodide.................. 128 test for, Bettendorf's......... 75 nitrate.................... 129 Hager's............. 30 oxalate (as reagent).......... 26 2Marsh's............ 28, 74 phosphate................. 130 Reinsch's.............75 sesqui-carbonate.......... 126 Arsenici iodidum........ 154 sulphydrate (as reagent)...... 26 Arsenicum album................ 73 valerianate............. 131 iodatum................... 154 Amnmonium benzoicum............ 124 Arsenious acid.................. 73 bromatum................. 125 iodide. 154 carbonicum.................. 126 Arsenite of potassium, solution of.. 254 chloratum................. 127 Atomic weights of elementary bodies 377 chloratumferratum........ 201 Atropia....................... 155 iodatum................. 128 Atropice sulphas............. 155 muriaticum................. 127 Atropinum..................... 155 muriaticum martiatum........ 201 suliphuricum.,............... 155 anitricum................. 129 phosphoricum............. 10 B. valeriavicum............... 131 Barii chloridum................ 156 Amylic alcohol............. 122 Barium chloride................ 156 Aniline sulphate (as reagent)...... 22 hydrate (as reagent).......... 27 INDEX. 385 Barium nitrate (as reagent)...... 27 Calcaria phosphorica............. 169 Baryla muriatica................ 156 Calcii carbonas praecipita......... 167 Baryumz chloratum......... 156 lhypophosphis............... 168 Belnzoate of ammonium........... 124 pl/osphas praecqi)itata......... 169 Benzoic acid................... 75 Calcined magnesia............... 258 Bibasic phosphate of iron....... 213 Calcis carbonas praecipitaeta....... 167 Biborate of sodium.............. 331 hypophosphis............ 168 Bicarbonate of potassium......... 286 liquor.......... 247 sodium.............. 332 phosphas praecipitata......... 169 Bichloride of mercury............ 225 Calcium carbonate........... 167 Bichromate of potassium.......... 287 hydrate, solution of......... 247 Biniodide of mercury............. 229 hypochlorite.............. 170 Bismuth and ammonium, citrate of. 157 hypophosphite........... 168 carbonate of................ 158 phosphate.................. 169 nitrate of............. 159 Calcium carbonicumn.............. 167 valerianate of........... 164 hypochlorosum............... 170 Bismut/hi et ammoii citras........ 157 pophosphoosum.......... 168 carbonas.................... 158 phosphoricum................ 169 subnitras......... 159 Calomel.............. 226 valerianas................... 164 Calx chlorata.............. 170 Bismuthous carbonate............ 158 chlorinata.................. 170 nitrate..................... 159 Carbolic acid................ 78 valerianate............. 164 Carbon bisulphide...... 173 Bismuthum album.............. 159 bisulphuret, of.............. 173 et anmmonium citricurn........ 157 Carbonate of ammonium......... 126 carbonzicum.................. 158 bismuth.................... 158 subnitricum................. 159 calcium.............. 167 valerianicum................. 164 iron........................ 214 Bisulphide of carbon............. 173 iron, saccharated.......... 197 Bisulphuret of carbon............ 173 lead....................... 279 Bitartrate of potassium........... 288 lithium.............. 256 sodium (as reagent)........... 26 magnesium................. 259 Bitter almonds, oil of............. 274 potassium, crude.......... 292 water of................... 146 potassium, purified.......... 294 Black oxide of copper............ 189 potassium, pure.............. 295 ironii................ 211 sodium..................... 334 manganese............ 262 cairbonei sulphurelum e........... 173 Bleaching-powder............... 170 Carboneurn sulhuratum......... 173 Blue, Prussian............... 206 Centimetre................ 52 vitriol......... 191 Cerii oxalas..................... 174 Boracic acid................... 78 Cerium oxalate............. 174 Boric acid.............. 78 Cerium oxalatum........ 174 Borax................ 331 Cerussa.................. 279 Bromide of ammonium..... 125 Chalk, precipitated.............. 167 potassium............. 290 Chili saltpetre................... 343 Bromides, distinction from chlorides Clhinoidinum................... 326 and iodides.............. 125, 291 Chininum...................... 312 Bromine....................... 165 hydriochloratum............. 319 Brominium.................... 165 hydrochloricurn....o... 319 Bromum............... 165 sulphuricum................ 320 Burettes..................... 55 tanicum..324 Butter of antimony............ 246 valerianicumn............. 325 Butyram anlironii............... 246 Chloral alcoholate........... 176 hydrate..................... 175 C. Chlorali hyderas................. 175 Cadmii sulphas............. 167 Chloralum hydratum crystallisalum. 175 Cadmium sulphate............... 167 Chlorate of potassium.......... 297 Cadmium sulphuricum............ 167 Chloride of ammonium.......... 127 Calcar-ia carbonica praecipitataa.... 167 antimony..............246 chlorata.................... 170 barium.................... 156 hypochlorosa................. 170 iron..................... 98 25 386 INDEX. Chloride of sodium............... 335 Digitalinum.................... 194 zinc..................... 366 Dinitrosnilphide of iron (as reagent).. 27 Chlorides, distinction from bromides Distilled water................... 149 and iodides,...........-. 305, 342 in tests........... 15 Chlorinated lime................. 170 Dithionate of sodium............. 339 Chlorine water................... 147 Chloroform.........1.......... 178 E. Chlor*of*ori1*um............... 178 Elementary bodies, with their atomic Chromic acid.................... 80 symbols and weights......... 377 Cinchona-bark, estimation of...... 313 Emetia............... 195 Cinchonia sulphate............ 81Emetinurn..................... 195 Cinchoniac sulphas............... 181 E.............. E.inmbar...................... 195 Citrate of bisnluth and ammonium... 157 ethylic........... 114 iron 200 nitrous...........it..... 351 iron ad ammonium......... 201 Ethyl acetate.................... 116 iron and quinia.......... 204 nitrite.... 351 lithium................... 25 oide.......... 114 Citric acid..............ty.. 80114 aEtylic ether................... 114 Codeiaty..................... 182 Codeinunzu.... 182 SZF Coffeia....................... 183 CQoeinzUm... 8.................183 Fehling's soltion (as reagent)..... 28 Colchicia... 184 Frri aettis, liuor.......... 247 ColcehicinumEn.....184 nias.................. 196 Common salt.............. 335 carons 214 Conia........................ 185 carbonas saccharata.......... 197 Conziinum.................. 185 chloriduom....... 198 Copper, aetate of................. 188 cits.200 ammonio-sulphate of......... 193 et antloniei chloridum......... 201 blackr oxide of......... 189 et anonii ci..as. 201 subacetate of..............t188 et ammonii su1phas.... 202. sulphate of.............. 191 et amonzo.ii tas................ 203 Corrosive sublimate............. 225 etpotassii tartras......... 201 Cream of tartar............... 288 et quiniae citras............. 204 Creasote.................... 186 ferroc2eanidurn........... 206 Coeasofum...................... 186 hlypophospis.. 207 Creta precipitate................ 167 lactas.................... 209 Crocus martis cstringes.210 oxim.................. 210 Crocus martis aperitivus.......... 214 oxidum magneticum..... 211 Cubic centimetre................ 52 oxidum niarum.............. 211 Cbopri acetas................... 188 perchloridum............ 198 oxidm................... 189 pcrnitlratis, liqor...................... 248 subapetas.................. 188 per oxiduam ihydratum......... 210. sblakoidh os f.............. 191 phospihas............. 212 Cupric acetate............... 188 pyropaosphnas........... 213 oxide................. 1. 189 ptirop,iospias et eanmo.ii citras. 214 subacetate................. 88 suberbo neis....... 214 sulphate............. 191 suzbsuzlphtisliuor........... 249 C'eUprum aceticum....... 188 sulsphas............... 215 amreoniatu r.............. 193 su8ph1Alis, liqu................. 249 oxydatuc1.......... 189 tersulphatis, liquor....... 249 srtlpa utricut................. 191 aleriaas..eia............... 217 sulphuriC, m amoniatum......... 193 Ferric acetate, solution of........ 241 Cyanide of mercurys...........,228 chloride ma..e.i........ 198 citrate..................... 200 D. dinitrosulphide (as reagent).... 271 Decantation.............. 16 hydr1ates.................... 210 Digitalin................... 194 hypophosphito................ 207 INDEX. 387 Ferric nitrate, solution of.......... 248 G. oxide....................... 214 Gallic acid.82 pernitrate, solutiou of........ 248 Gelatin (as reagent)............... 32 pyrophosphate..............213 Glacial acetic acid................ 69 sulphate, solution of..... 249 phosphoric acid.............. 96 valerianatef.................. 217 Glauber's salt................... 347 Ferricyanideof potassium(asreagent) 25 Glycerin............ 221 Ferri-ferrocyanide. 206 Glycerinum...........221 Ferrocyanide of potassium......... 01 Golden sulphur.......... 140 Ferrous carbonate............... 214 Gramme.. 52 carbonate, saccharated.. 197 uaranine. 183 ferric arseniate.............. 196 ferric hydrate............... 211 ferric phosphate.......... 212 iodide....................... 208' Hepar sulphuris................. 310 iodide, saccharated........... 208 Hippuric acid................... 76 lactate..................... 209 Hydrargyri bicloridum........... 225 sulphate.................... 215 chloridum corrosivun......... 225 sulphate (as reagent).......... 27 cloridumn mite.............. 226 Ferrumr......................... 218 cyanidum.....,,,.......... 228 arsenicum................... 196 iodidum rubrum............. 229 carlbonicum saccharatum...... 197 iodidul viride............... 231 citricurm.....................200 nitratis, liquor............... 250 citricum anmmoniatzum........ 201 oxidunm favum............... 232 et ammonium chloratumn...... 201 oxidumr rubrum............ 232 et ammonium citricumn........ 201 perchloriclum............... 225 et ammonium sulpthuricum..... 202 sbchloridm...... 226 et ammoniumn tartaricuzn...... 203 subnitras................ 235 et chininzum citricum....... 204 sulphas flava............. 236 etpotassiumz tartaricum... 204 sulphuretum rtbrum. 236 ferrocyanatum............... 206 lydrargylr'u................... 238 hydricum................... 214 amidato-bichloratum......... 240,iypophosphlorosum.. 207 ammoniatuni. 240 iodatum.................... 208 ammoniaturn bichloratum. 240 iodatum saccharatum......208 bichloratum................. 225 lacticum.................... 209 cldoratum mite............... 226 oxydatumn fuscum........ 214 corrosivum saubli tnztz........ 225 oxydatum rubrum............ 210 cyanattn................... 228 oxyclulato-oxgd dlum........... 211 iodatum flavum.............. 231 oxydulato - oxydatum plhosphori- iodatum rubrum.............. 229 cum...................... 212 nitricum oxydulatumn.......... 235 plhosphoricum................ 212 oxyJlatum rubrumt....... 232 pulveratum.................. 218 oxldatum via hurnida paaturnm. 232 pyrophospho ricum............ 213 praecipitateum album.......... 240 pyrophosphoricum cuzn amzmfoonio sulphuratum rubr:m.......... 236 citrico.................... 214 sulphuricum flavum.......... 236 redactumn.............. 218 Hydrate of ammonium, solution of.. 142 reductum.................. 218 (as reagent).................. 26 sesqui-chloratum.......... 198 of barium (as reagent)........ 27 subcarbolicum............... 214 calcium, solution of........... 247 sulphuricum................. 215 chloral..................... 175 sulphuricum oxydatum ammo- oxide of iron................ 210 niatum................... 202 potassium................... 298 tartaricurn ammoniatum....... 203 sodium..................... 337 valerianicaum........... 217 Hydrochloric acid.............. 83 Flores antimonii......... 134 Hydrochlorate of morphia......... 271 benzoes...................... 75 quinia...................... 319 sulphuris................... 361 Hydrochloride of nmorphia......... 271 zinci....................... 368 quinia................... 319 Fowler's solution................. 254 Hydrocyanic acid............... 88 Fusel-oill.12................. 122 Hydrogen, nascent (as reagent).... 28 388 INDEX. Hydrogen, sulphuretted (as reagent). 22 Iron, potassio-tartrate of.......... 204 Hydrosulphuric acid (as reagent)... 22 powder............. 218 Hypochlorite of calcium......... 170 pyrophosphate of........... 213 lime........... 7.... 10 pyrophosphate of, with citrate Hypophosphite of calcium......... 168 of ammonium.............. 214 iron...................... 207 and quinia, citrate of......... 204 lime....................... 168 saccharated carbonate of..... 197 sodium.................. 339 sesqui-chloride of............ 198 Hyposulphite of sodium........... 339 subcarbonate of............. 214 sulphate of................ 215 I. tersulphate of, solution of..... 249 Indigo sulphate, solution of (as re- valerianate of............... 217 agent)..,.............. 22 sulphuric acid (as reagent)..... 21 K. Iodate of potassium (as reagent.... 24 Kalium aceticum............... 285 Iodide of ammonium.............. 128 bicarbonicum.. 286 marsenicu, rd................... 1 bichromicumn................ 287 ironi....................... 2084 ldon.................. 28..... 281 bicartaricum................. 288 mleadii, nc...........t n... 281 biromatum................... 290 mercury, reen.............231 carbonicum udum.......... 292 sodiuryr............... 341 mercury, red................ 229 6arbonicum depur........ potassium. t.................. 29 causticum... 298 sulphur..................... 363 chloricum............. 297 Iodides, distinction from bromides. cro m rurum... 287.,,, ferroc.ana2um...... sr........ 301 distinction from chlorides ferroanatum volumetric test-solution of..... 63 nitricum................... 306 water (as reagent).2.4 e c..... 24 Iodinized potassium iodide (as re- sup m.............. 310 agent)oi.................... 25 L ic i 9 sulphuricum................. 309 Iodinutmr........................ 243 tataoifu..............196i f.... 311 Iodoform................... 24 e s minerale.......... 13 citdofornum..................... 242 K[reosotum...................... 18 6 Jodumo.................. 2....... 243 Iron......................... 218 Iron, acetate of, solution of........ 247 alum....................... 202 Lac sulphuris................... 359 ammonio-chloride of.......... 201 Lactate of iron.................. 209 ammonio-citrate of.......... 201 Lactic acid..90................ 90 ammonio-sulphate of.......... 202 Lead, acetate of................. 278 ammonio-tartrate of.......... 203 carbonate of................ 279 arseniate of................. 196 iodide of.................. 281 carbonate of................ 214 nitrate of................., 282 chloride of................. 198 oxide of................... 282 citrate of.................. 200 red oxide of................ 4 284 ferrocyanide of.............. 206 subacetate of, solution of.......251 hydrated oxide of............ 210 subcarbonate of............. 279 hypophosphite of........... 2 sugar of278 iodide of.......... 208 white........... 279 iodide of, saccharated......... 208 Lime, carbonate of.............. 167 lactate of.................. 209 chlorinated................ 170 magnetic oxide of............ 211 hypophosphite of........... 168 nitrate of, solution of......... 248 phosphate of................169 perchloride of.............. 198 water..................... 247 peroxyhydrate of............ 210 Liquor ammonie................. 142 pernitrate of, solution of...... 248 ammonii acetalis............. 245 persulphate of, solution of..... 249 ammonii caustici............. 142 phosphate of................ 212 antimnonii chloridi....... 246 IN'DEX. 389 Liquor calcis...... 247 Mercuric sulphate........2....... 236 chlori...................... 147 sulphide.................. 236 ferri acetatis................ 247 Mercurius dulcis................ 226 ferri chloridi................ 198 Mercurous chloride.............. 226 ferri nitratis............... 248 iodide..................... 231 ferr i pernitratis............. 248 nitrate.................... 235 Jerri persulphatis........... 249 Mercury.......... 238 ferri subsulphatis............ 249 ammoniated................ 240 ferri-tersulphtis........... 249 ammonio-chloride of......... 240 hydrarqyri nitratis........... 250 biniodide of................ 229 hydrargyri nitrici oxydulati.... 235 cyanide of.............. 228 hydrargyri nitrici oxydati.... 250 oxide of............. 232 kalii arsenicosi.............. 254 perchloride of............... 225 kalii caustici................ 252 pernitrate of, solution of.. 250.hatrii caustici............... 254 protoiodide of......... 231 pulmbi subacetatis........ 251 subchloride of............... 226 potasse..................... 252 subnitrate of................ 235 potassii arsenitis............. 254 sulphate of.............. 236 potassii hydratis............ 252 sulphide of................. 236 sodoe....................... 254 Methenyl iodide............... 242 sodii hydratis................ 254 Mineral kermes................. 135 stibii chlorati............. 246 Minium........................ 284 Litharge............. 282 Morphia.................. 266 Lithargy.rum........ 282 acetate.271 Lithii carbonas.................. 256 estimation of, in opium....... 267 citras................. 257 estimation in tincture of opium. 269 Lithium carbonicum........... 256 hydrochlorate.............. 271 citricum.................... 257 hydrochloride........... 271 Litmus-paper............. 32 sulphate......... 272 solution... 32 Morphice acetas................. 271 Litre-flasks and jars............... 53 hydroc/loras................ 271 Lunar caustic.................. 150 murias.................... 271 suMphas................... 272 Morphinum 266 aceticum.......... 271 Magnesia....................... 258 hydrochloricum.............. 271 calcined................... 258 sulphuricnum................ 272 Magnesia alba................... 259 Mucilage of starch (as reagent)..... 22 carbonica.................. 259 Muriatic acid.................. 83 sulphuria................... 260 Mustard-oil.. 277 ucsta i................... 258.Magnesii carbonas................ 259 N oxidmt................... 258 sulphas..................... 260 Natrio-kalium tartaricum.......... 308 Magnesium carbonate............. 259 Natrium aceticum............... 329 oxide..................... 258 arsenicum.................. 330 sulphate................... 260 biboricum................... 331 Magnetic oxide of iron........... 211 bicarbonicum............... 332 Manganese, black oxide of........ 262 carbonicum................. 334 dioxide of.................. 262 causticum.................. 337 sulphate of................. 264 chloratumn.............. 335 Manganesii oxidum nigrum........ 262 hydricum................... 37 sulphas.................. 264 hiypophosphorosumn........... 339 Manganous sulphate.............. 264 hyposulphurosum............ 339 Mfanganunm hyperoxydatuwm....... 262 iodatum................... 341 sulphuricum................. 264 nitricum................... 343 Mercuric chloride................ 225 phosphoricum............ 345 cyanide..................... 228 pyrophosphoricum........... 346 iodide..................... 229 subsulvphurosum............. 339 nitrate, solution of........... 250 sulphuricum................. 347 oxide.................. 232 sulphurosum............... 350 390 INDEX. Nessler's reagent.......... 25 Pipette........................ 54 Nicotia..................... 273 Platinic chloride (as reagent)...... 28 Nicotinum..................... 2173 P'umbi acetas.................... 278 Nitrate of ammonium............. 129 carbonas................... 279 bismuth.............. 159 iodidum................... 281 iron, solution of............ 248 nitras............. 282 lead........................ 282 oxidurn..................... 282 mercury............... 235, 250 oxidurn rubrlm.. 284 potassium............. 306 subacetas, liquor............ 251 silver............... 150 subearboneas............ 279 sodium.................... 343 Plumbic acetate.................. 278 strychnia.................. 357 carbonate....,.... 279 Nitre................... 306 iodide.281 sweet spirit of.............. 351 monoxi.de......... 282 Nitric acid................... 91 nitrate..................... 282 Nitrite, ethyl................ 351 plumbate.................. 284 subearbonate................ 279 0. subacetate, solution of........ 251 Plumbum aceticum............... 278 Oil of bitter almonds............. 274 P a eicum 278 carbonicun.................. 279 mustard.................... 277............... iodaium.................... 281 Oleum amygdalarum am rarum.... 274 niticum.281..... 82 sinapis..................... 277 um282 Opium, estimate of morphia strength 267 oxydctun fuscm.282 I n ~ ~b rubrum............ 284 Oxalate of cerium... 174 Potash crude........ 1 95 Potash, crude............ 299 volumetric test-solution of.... 56 pure caustic................. 298 Oxide of antimony............... 134 Potessa. 298 oass liquor. 52 copper.................... 189 It ~id~~~~copper ~.11 Potassii acetas................... 285 iron...... 210, 211, 214 bicarbonas.................. 286 lead................... 282, 284 bichro magnesium................. 258 28 manganese, black....... 262 bromdum. 288 bromidum.......... 290 mercury.................... 232 silver............ 154 carbonas cruda............ 292 zinc......., 368 carbonas depurata............ 294 Oxy-carbonate of bismuth.... 158 r..... 29 -chloride of antimony......... 246..................... -nitrate of bismuth........... 159 ferrocyaniz........... 301 -sulphide of antimony........ 135 ydrs cc.....299 kydras pcrea................ 298 iodiduma.................. 302 iodidum 302 itras...................... 306 Pearlash........................ 292 pelrmangeanas............... 307 purified..................... 294 et sodii tartras.............. 308 Pentasulphide of antimony........ 140 sulplas................... 309 Perchloride of iron............... 198 sulphuretum......... 310 mercury......................225 sulphidum................. 310 Permanganate of potassium....... 307 tartras...................... 311 Pernitrate of iron, solution of...... 248 Potassio-antimonious tartrate...... 131 mercury, solution of.......... 250 -ferric tartrate............. 204 Peroxyhydrate of iron............ 210 -mercuric iodide (as reagent).. 25 Persulphate of iron, solution of.... 249 Potassium acetat....... 285 Phenic alcohol................. 78 antimoniate (as reagent). 25 Phenic acid................... 78 arsenite, solution of.......... 254 Phenrol......................... bicarbonate........... 286 Phosphate of ammonium.......... 130 bichromate................. 287 calcium..................... 169 bitartrate................... 288 iron........................ 212 bromide..................... 290 lime.................... 169 carbonate, crude............ 292 sodium..................... 345 carbonate, purified.......... 294 Phosphoric acid................. 96 carbonate, pure............. 295 INDEX. 391 Potassium chlorate............... 297 Sal ammoniacurn............... 127 ferricyanide (as reagent)...... 25 Saltpetre.............. 306 ferrocyanide.................. 301 Chili............... 343 hydrate..................... 298 Salt, common.................... 335 iodate (as reagent)........... 24 of tartar............... 295 iodide...................... 302 Santonin........................ 328 nitrate.............. 306 Santoninum..................... 328 permanganate........... 307 Seignette salt............ 308 prussiate.............. 301 Ses.qui-carbonate of ammonium.... 126 and sodium tartrate.......... 308 chloride of iron.............. 198 sulphate................ 309 Silver, nitrate of................. 150 sulphide.............. 310 oxide of.................... 154 sulphuret..... 310 Sinapis, oleum............. 277 sulphocyanide (as reagent).... 25 Soda......................... 337 tartrate.............. 311 Sodc liquor.................... 254 Precipitation............. 15 Sodii acetas...................... 329 Precipitated carbonate of lime...... 167 arsenias............. 330 oxide of mercury...... 232 biboras................ 331 phosphate of lime. ].. 169 bicarbonas.................. 332 sulphur.................... 359 carbonas........... 334 Protochloride of mercury.......... 226 chloridum................... 335 Protoiodide of mercury........... 231 hydras...................... 337 Prussian blue............... 206 hyp opihosphis........ 339 Prussiate of potassium............ 301 hyposlplhis............. 339 Pyrolusite................... 262 iodidurm.............. 341 Pyrophosphate of iron.......... 213 nitras....... 343 in scales..... 214 plhosphas..... 345 of iron with citrate of ammo- pyrophosphas............ 346 nium..................... 214 sulplhas... 347 of sodium............. 346 szuphis.................... 350 Sodium acetate............. 329 -Q arseniate.............. 330 Quicksilver...... 238 biborate............ 331 Quinia................ 312 bicarbonate............ 332 ferrie citrate............ 204 bitartrate (as reagent),....... 26 hydrochlorate........ 319 carbonate.................. 334 hydrochloride........ 319 chloride...... 35 sulphate.............. 320 dithionate....... 339 tannate............. 324 hydrate............... 337 valerianate...... 325 volumetric test-solution of. 60 Quinicea hydrochdloras............ 319 hypophosphite............... 339 murias.................... 319 hyposulphite........... 339 suiph/as.................... 320 volumetric test-solution of. 63 tannas.............. 324 iodide............ 341 valerianas................. 325 nitrate............... 343 Quinine............,......... 312 phosphate............. 345 Quinoidine......... 326 and potassium tartrate........ 308 Quinoidinum................ 326 pyrophosphate...... 4..... 346 subsulphite................. 339 R. sulphate................. 347 Reactions............... 18 sulphite............ 350 Reagents. 18, 20 tetraphosphate.... 346 Red iodide of mercury............ 229 Sodium tartaratumin........... 308 oxide of lead........ 284 Solution........ 15, 37 oxide of mercury........... 232 alcoholic, of ethyl nitrite..... 351 precipitate........, 232 alcoholic, of ammonia......... 142 sulphide of mercury.......... 236 ammonium acetate........... 245 Rochelle salt................... 308 ammonium hydrate.. 142 antimonious chloride......... 246 S. calcium hydrate......... 247 Saccharated carbonate of iron...... 197 chlorine.................... 147 iodide of iron............... 208 ferric acetate............... 247 392 INDEX. Solution, ferric chloride........... 198 Sulphite of sodium............... 350 ferric nitrate................ 248 Sulphocyanide of potassium (as referric sulphate.................249 agent)..................... 25 mercuric nitrate............. 250 Sulphur, flowers of............... 361 mercurous nitrate............ 235 golden..... 140 potassium arsenite........... 254 iodide of.................. 363 potassium hydrate........... 252 precipitated.................. 359 sodium hydrate............. 254 sublimed..... 361 triplumbic acetate............ 251 Sulphur auratumn antimonii....... 140 Spirit of nitrous ether............ 351 depuratum.................. 362 Spirilus oetheris nitrosi............ 351 iodatum.................. 363 ammohice.................. 142 lotum...................... 362 nitri (lulcis.................. 351 prcecipitatum..... 359 nitroso-tethereus............... 351 sublimatum.................. 361!~ectifcatus................... 118 Sulphurated antimony............ 135 Stannous chloride (as reagent)..... 28 Sulphuretted hydrogen...... 22 Stibii chlorati, liquor............. 246 Sulphuret of potassium........... 310 Stibium oxyduLtumn................ 134 Sulphuric acid................ 104 suiphuratum aurantiacum..... 140 acid mucilage of starch (as resulphuratum nigrum.......... 138 gent).................... 22 sulphuratum rubeum.....1.... 135 Sulphuris iodidum................ 363 Strychnia........................ 354 Sulphydrate of ammonium (as renitrate...................... 357 agent)....................... 26 sulphate................... 358 Sweet spirit of nitre............. 351 Stryclhnic nitras................. 357 Syrupus ferri iodidi.............. 203 sulphas..................... 358 Strychlinum nitricum............. 357 T. sulphuricuom................. 358 Tannate of quinia................ 324 Subacetate of copper............. 188 Tannic acid..................... 109 lead, solution of............. 251 Tartar, cream of................. 288 Subcarbonate of bismuth.......... 158 emetic..................... 131 iron........................ 214 Tartaric acid.................... 110 lead........................ 279 Tartarated antimony.......... 131 Subehloride of mercury........... 226 Tartarus depuzratus............... 288 Sublimed sulphur.......... 361 satronatats............. 308 Subnitrate of bismuth............ 159 stibiatus.............. 131 mercury................. 235 Tartrate of iron and ammonium.... 203 Subsulphate of iron, solution of.... 249 of iron and potassium......... 204 mercury.................... 236 of potassium................ 311 Subsulphite of sodium............ 339 of potitssium and antimony.... 131 Succinic acid.................. 102 of potassium and sodium...... 308 Sugar of lead.................... 278 Tersulphate of iron, solution of.... 249 Sulphate of aluminium........... 124 Test-papers...................... 32 atropia................... 155 Test-solutions, volumetric, of..... 62 cadmium................ 167 argentic nitrate.............. 62 cinchonia.................. 181 iodine..................... 63 copper..................... 191 oxalic acid.................. 56 iron........................ 215 sodium hydrate.............. 60 iron and ammonium.......... 202 sodium hyposulphite.......... 63 magnesium................. 260 Theine......................... 183 manganese........... 264 Thermometric scales, conversion of mercury.................... 236 degrees of................ 378 niorphia.................... 272 Tincture of opium, estimation of potassium.................. 309 morphia strength of........... 269 quinia....................... 320 Tribasic ammonium phosphate..... 130 sodium.................... 347 calcium phosphate........... 169 strychnia.................. 358 sodium phosphate........... 345 zinc........................ 370 Triplumbic acetate, solution of.... 251 Sulphide of antimony............. 138 tetroxide.................... 284 mercury.................... 236 Trisulphide of antimony........... 138 potassium.................. 310 Troy-weight..................... 52 INDEX. 393 Turbidity....................... 16 Weights, conversion of metric into Turmeric paper................. 33 troy.......................... 381 solution.............. 33 White arsenic................... 73 Trpehum mineral.............. 236 lead............... 279 precipitate.................. 240 V. vitriol. 370 Wood-tar creasote......... 186 Valerianate of ammonium........ 131 bismuth.................. 164 Y. quinia..................... 325 Yellow iodide of mercury...... 231 ~~~zinc. ~~ ~~ ~~ 3'72 oxide of mercury............ 232 Valerianic acid............. 111 prussiate of potassium....... 301 VeratriU nZ........................ 364 Veratria.......................... 364 subsulphate of mercury....... 236 Veratrinum..................... 364 Verdigris.................... 188 Z. Vermilion.............. 236 Zinc acetate..................... 365 Vinegar........................ 67 chloride.................... 366 Vitriol, blue..................... 191 oxide....................... 368 white........... 370 sulphate................. 370 Volumetric test-solutions. (See Test- valerianate................. 372 solutions.) Zinci acetas..................... 365 cTloridum................. 366 W. ~ oxidum.................... 368 Washing-bottle.................. 16 sulphas.................... 370 Water, chlorine........................... 147 valerians 372 Water, chlorine.. 14'7 valerianas................... 372 distilled............... 149 Zincum Aceticm................. 365 distilled, in tests............ 15 chloratum.............. 366 lime............ 247 muritzicum.............. 366 of bitter almonds.......... 146 oxydatum................... 368 Weights, atomic.............. 377 sulpbhuricum............... 370 conversion of troy into metric. 380 valerianicum.............. 372 THE END. TIEH WORKS OF PROF. JOHN TYNDALL, LL.D., F.R.S. Heat as a Mode of Motion. One vol., I2mo. Cloth, $2.00. "My aim has been to rise to the level of these questions from a basis so elementary, that a person possessing any imaginative faculty and power of'concentration might accompany me."-rom A uthor's Preface. On Sound. 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