||§§||| HI ■111 Ssilsisfe' • ALBERT R. MANN LIBRARY New York State Colleges of ., . , , Agriculture and Home Economics •AT Cornell University Cornell University Library RJ 216.M51 Milk analysis «£ W^-SKEfiffif 3 1924 003 706 235 Cornell University Library The original of this book is in the Cornell University Library. There are no known copyright restrictions in the United States on the use of the text. http://www.archive.org/details/cu31924003706235 MILK ANALYSIS INFANT FEEDING. A PRACTICAL TREATISE Oft THE EXAMINATION OF HUMAN AND COWS' MILK, CREAM, CONDENSED MILK, ETC., DIRECTIONS AS TO THE DIET OF YOUNG INFANTS. BY ARTHUR V. MEIGS, M.D., PHYSICIAN TO THE PENNSYLVANIA HOSPITAL AND TO THE CHILDREN'S HOSPITAL; FELLOW OF THE COLLEGE OF PHYSICIANS OF PHILADELPHIA, ETC. PHILADELPHIA: P. BLAKISTON, SON & CO. No. 1012 Walnut Street. 1885. Copyright, 1885, by P. Blakiston, Son & Co. TO THE MEMORY OF DR. JOHN FORSYTH MEIGS, WHO HAD VAST EXPERIENCE IN THE ARTIFICIAL FEEDING OF INFANTS, AND WHO WAS ENDOWED WITH A RARE FACILITY FOR THEIR SUCCESSFUL TREATMENT; BY WHOSE ADVICE THIS WORK WAS UNDERTAKEN, AND TO WHOSE ENCOURAGEMENT ALONE IS DUE ITS COMPLETION, THIS BOOK IS AFFECTIONATELY DEDICATED, BY HIS SON, THE AUTHOR. PREFACE. Much that is contained in the following pages has already been published in the form of papers read before the Philadelphia County Medical So- ciety and the College of Physicians of Philadelphia, and will be found in the transactions of these socie- ties ; but the subject has seemed to the author one of such great importance, and the diversity of opinions upon it expressed by different writers so great, that this little work is published with the hope that it may somewhat aid in placing the matter upon a more settled basis. If only some uniformity of opinion could be arrived at in regard to the much-vexed question of the composition of human milk, it would be a great step in advance toward the attainment of some positive conclusion in regard to the artificial feeding of infants. The author, after long and careful study of the matter, is convinced that human milk contains a very much less quantity of casein than is commonly attributed to it, and puts forth his reasons, and a detail of the methods by which the conclusions v VI PREFACE. were attained, in the hope that in time they may- be decided to be correct and be accepted. Even, however, if the subject-matter of the work only ex- cites controversy, and in the course of time comes to be disproved and other positive and correct con- clusions with regard to the composition of human milk can be attained, and thence some improve- ment . in the methods of infant feeding made, the author will be satisfied that the work expended has not been in vain. TABLE OF CONTENTS. PAGE Dedication iii Preface v Introduction 9 CHAPTER I. — Method of Analysis 13 CHAPTER II. — Statement of Results and Compari- son of Human and Cows' Milk 26 CHAPTER III. — Proof that Human Milk contains only about One Per Cent, of Casein 38 CHAPTER IV. — Observations upon Methods of Analy- sis Heretofore Pursued 49 CHAPTER V. — Artificial Feeding of Infants 61 CHAPTER VI.— Conclusion 87 Bibliography 97 Index 99 VII INFANT FEEDING AND MILK ANALYSIS. INTRODUCTION. That it is desirable, from a utilitarian as well as from a moral point of view, that as large a number of the children born into the world as possible should live, is strongly evidenced by a contrast of the history of the Jews with that of any other peo- ple. Their fertility and increase, often under the most adverse circumstances, is one of the wonders of history ; and they are the only people whose laws have always taught and enjoined that one of the first duties is the care of all children born. The Greeks and Romans, with their boasted civilization, — which it is now so much the fashion to admire — ordered by law, the destruction* of all deformed and feeble infants, and even, at times, of the healthy ones, to prevent too rapid an increase of the popu- lation ; and it was only toward the end of the third, and even in the fourth century of the Christian era, that the teachings of Christianity began to effect the revocation of the then existing barbarous cus- * Histoire des En/ants Abandonnis, par Ernest Semichon. Paris, 1880. 2 9 IO INFANT FEEDING AND MILK ANALYSIS. toms with regard to infanticide. During all this time, and for many centuries before, the law and custom of the Jews enjoined the greatest care and tenderness for all children, even the sickly and deformed. That this custom did not entail any de- generation of the race, from feeble and deformed individuals reproducing their species, the event has proved ; for, while other nations have made laws ordering the destruction of all feeble or deformed infants, to prevent such a contingency, these peoples have died out and disappeared from the face of the earth, or have relapsed into barbarism, or again, like the Chinese, who are noted for their careless- ness about the crime of infanticide, have remained for centuries, fossil-like, without either advancing or retrograding. During all this time, the Jews, who have pursued an opposite course, and have always manifested the greatest tenderness for their infants, although scattered over the face of the earth, have increased constantly in numbers and power, and have certainly undergone no degeneration in either their physical or mental attributes. The historian Gibbon, in his memoirs of his life and writings, says, "the death of a new-born child before that of its parents may seem an unnatural, but it is strictly a probable event; since of any given number the greater part are extinguished be- fore their ninth year, before they possess the facul- ties of the mind or body. Without accusing the profuse waste or imperfect workmanship of Nature, I shall only observe, that this unfavorable chance was INTRODUCTION. I I multiplied against my infant existence. So feeble was my constitution, so precarious my life, that, in the baptism of my brothers, my father's prudence successively repeated my Christian name of Edward, that, in case of the departure of the eldest son, this patronymic appellation might be still perpetuated in the family." Then, after recounting how his life was a constant battle with disease until he was six- teen years of age, he tells that he believes he owed its preservation to the constant care and watchful solicitude of his aunt, and says, " I have never pos- sessed or abused the insolence of health ; but since that time few persons have been more exempt from real or imaginary ills." Gibbon's five brothers and sister all died in infancy, but he, whose life at first seemed the most precarious of all, lived to write the history of the Roman Empire. Yet, if this man had been born during the days of which he wrote so well, he would have been slain in early infancy, or exposed upon a public highway, as too feeble a specimen of humanity to be allowed even a chance of life ! That many infants might be saved who now die, is shown by an examination of the mortality records of civilized nations. It is then seen that the rela- tive number of deaths among the very young is enormously in excess of that in later life ; and this will, of course, always be so, for even in vegetable as well as in animal life the younger individuals are much more delicate, and during the early por- tion of their lives surrounded with many pitfalls in 12 INFANT FEEDING AND MILK ANALYSIS. the shape of disease and accident. Still, when it is considered what an enormous proportion of the deaths of infants under two years of age is from nutritional disorders, it becomes evident that many of them must be avoidable. The total number of deaths * recorded and tabu- lated as occurring in the United States, during the census year of 1880 is 756,893 ; of these 175,266 were of children under one year of age, and 302,806 were under five years of age. Thus nearly one- half of the total number of deaths was of children under five years of age, and nearly a quarter of the total number was under one year of age. During the year 1883, more than one-quarter of the total number of deaths that took place in the city of Philadelphia was of children under one year of age {Public Ledger, Jan. 1, 1884). These few figures seem to offer an abundant justification for such a book as this, for surely there is a crying need for the dissemination of knowledge which may lessen the mortality among young in- fants. * Medical News, Nov. 25, 1882. Mortality Statistics of the United States. CHAPTER I. METHOD OF ANALYSIS. It is unnecessary to elaborately discuss the use- fulness of milk analysis, for it goes without saying that anything which adds to the sum of our exact knowledge must be useful, even if it does not bear any visible fruit in immediate practical gain. It is, however, by the acquisition of a more precise under- standing of the composition of human milk alone, that we can hope for any improvement of our pres- ent methods of artificially feeding infants. Ad- vancement in this matter might be possible by two methods only ; first, by direct experiment upon in- fants, and second, by the acquisition of a precise understanding of the composition of human milk, which would enable us to compound a food more nearly resembling it than anything of which we have previously had knowledge. That our efforts in this direction have been thus far singularly unsuccessful does not admit of doubt, for it is universally con- ceded that the chances of life of an infant who has to be hand-fed from birth, are very much less than if he could be nursed by his mother or a wet-nurse. It is melancholy to think how many children die, year after year, simply because those who are most anxious for them to live do not know what to give them to eat ; yet such is the fact. During all the 13 14 INFANT FEEDING AND MILK ANALYSIS. years that have passed, experiment upon experiment has been made in all quarters of the world, and yet, to-day, the opinions upon the subject are as numer- ous, and as radically at variance, as they have been in the past. Experiment, then, it would seem, is not to lead us to the desired goal, and our only hope is that by carefully studying the composition of human milk, and seeking to imitate it, can we do anything to save the hundreds of thousands of infants who are, year after year, sacrificed to our want of knowledge. Analysis is also useful in that it enables us to detect any fraud that may be attempted by adulter- ating cows' milk which is offered for sale. That it is difficult to analyze milk correctly is proved by the fact that, although many have at- tempted it, the greatest variety of results has been arrived at, and the methods suggested have been as various as the results attained. As the only kinds of milk generally used in this country are cows' milk and that of the woman, these alone will be considered here. The analyses of cows' milk quot- ed by different authors are sufficiently nearly par- allel, to render it likely that an approximately exact knowledge of its composition has already been deter- mined ; the analyses of human milk, however, are so widely at variance as to leave much to be de- sired in that field. The conclusions of the various investigators of this latter portion of the subject, are so different as to render it certain that many of them have hit wide of the mark. METHOD OF ANALYSIS. 1 5 Perceiving this uncertainty, the author, having made many analyses and experiments endeavoring to arrive at a definite conclusion upon the subject, ventures to lay his conclusions before the profession. The method found most satisfactory — and it may be applied to cows' as well as human milk — is the following: — 15 c.c. of milk must be ob- tained ; of this 5 c.c. are discharged from a pipette into a small platinum dish, and at once the weight taken and noted. This dish is then placed in a water-bath, and the water kept at the boiling-point until the milk is completely dried, and ceases to lose weight. This, as Mr. Wanklyn points out, takes about three hours, when 5 c.c. of milk are used. (The most convenient water-bath is a deep skillet, and in this is placed a disk of copper, with holes in it, of such a size as to hold the platinum dishes to be used, the whole being floated upon copper air-chambers soldered to the under side of the disk. This apparatus may be left for hours in the bath without any watching, and yet the platinum dishes are constantly im- mersed in the boiling water.) As soon as the weight becomes constant, it must be noted, and the con- tents are then incinerated, best over a blast-flame, and the weight again noted. (In incinerating, the heat used must at first be moderate, and then grad- ually increased.) This gives, by the difference in weight before and after drying, the water lost ; by subtracting the weight of the dish from the total weight after drying, the total solids ; by subtracting 1 6 INFANT FEEDING AND MILK ANALYSIS. the weight of the dish from the total weight after incinerating, the ash is ascertained ; and, finally, by the difference in weight after drying and after incineration, the weight of solids not ash is ascer- tained. This last weight, however, does not enter into the final calculation, and is of no value except as a check to correct possible errors. At the same time that the first 5 c.c. are weighed, 10 c.c. must be weighed in another dish, care be- ing taken, of course, that the weight is exactly twice that of the 5 c.c. This is poured into a high, narrow bottle (the ordinary 100 c.c. graduated bottle answers the purpose), and 20 c.c. of distilled water added, this being used to wash all the milk from the vessel in which it was weighed into the bottle. To this are now added 20 c.c. of ether. The bottle must then be tightly stoppered and agitated violently for five minutes ; 20 c.c. of alco- hol are then added, and it is agitated for five min- utes more. If it is then set down for a few min- utes, the contents will be found to have separated into two layers ; on top will be found ether, con- taining fat in solution, and below will be a mixture of part of the ether, the alcohol, and the water, containing coagulated casein in suspension and the sugar in solution. The ethereal solution, which is on top, is then drawn off with a pipette, as nearly as can be done without disturbing the lower layer ; 5 c.c. of ether are poured on to mix with what fat is left, and this drawn off. Ether should be poured on and drawn off five times, 5 c.c. being used each METHOD OF ANALYSIS. 1 7 time, so as to remove all the fat. The ethereal solution of fat is now dried over warm water, and finally, for a few minutes, over boiling water ; the resulting weight — that of the dish being deducted — is, of course, the weight of the fat. There is now left in the bottle the sugar and casein, with the salts. The contents are carefully washed into a large platinum dish, and dried over the water-bath. The dried residue is treated with boiling water, and the dish and contents placed aside to settle. The undissolved casein soon settles to the bottom, and the clear solution of sugar is poured off. The solution of sugar is now again dried, and the same process repeated, the sediment being added to that which was obtained before. This must be done four or five times, until it is found that when boil- ing water is poured upon the dried sugar it dis- solves completely, no flocculi of casein being seen in the solution. The casein residue is then, after being dried, treated once or twice with boiling water, to wash out any sugar that may have been left in it, care being taken that none of the solid casein is poured off with the matter dissolved. This sugar is added to that formerly obtained, and the two substances are then ready for the final drying, which must be done over the water-bath, and con- tinued until they cease to lose weight sensibly. The two residues are then incinerated over the blast- flame, and the loss in the burning gives the weights of the casein and sugar. In calculating results, it is easiest to bring the 1 8 INFANT FEEDING AND MILK ANALYSIS. amount of each constituent up to what is contained in ioo c.c. This is done by multiplying the amounts of water and ash by twenty, as they are arrived at by the use of 5 c.c, and those of fat, casein, and sugar by ten, as they are arrived at by the use of 10 c.c. of milk. The sum of the amounts of the different constituents will be found to be, from one hundred and one, to one hundred and three. A use of the simple rule of three enables one easily from this to calculate the quantities in parts of one hun- dred. A comparison of the sum arrived at as above, with the weight of the original 5 c.c. of milk, multi- plied by twenty, to "obtain the weight of 100 c.c. of milk shows the error ; there being necessarily a slight loss, or sometimes an excess, owing to imperfect dry- ing of the sugar or casein in the second part of the process. The error is always very slight, if proper care has been exercised in the manipulations. Any analysis in which it amounts to as much as one-half of one per cent., particularly if there is excess and not loss, should be at once thrown out, for excess can only occur from carelessness. In an analysis carefully car- ried out by this process the usual error is from one- to two-tenths of one per cent., and any error larger than this is due to carelessness in manipulation. A very common source of error is imperfect drying of the sugar residue in the second part of the analysis, and great care and patience must consequently be exercised during this part of the process. The sugar residue must be kept constantly in the water-bath, METHOD OF ANALYSIS. 1 9 and the water in a state of active ebullition until the weight becomes absolutely constant, and this usually takes from twenty to twenty-four hours. In ana- lyzing human milk by this process, there is about seven-tenths of a gram of sugar to be dried, and, consequently, the drying takes much longer than if cows' milk is analyzed, when only about five-tenths of a gram are dealt with. For the reason that sugar is so difficult to dry perfectly, the water-bath apparatus described has been found invaluable, as by its use the dish of sugar can be kept immersed to an even depth in the boiling water as long as desired, for, as evaporation takes place and the water sinks lower and lower in the vessel, the dish, which is floated upon its surface, sinks too, whereas with the ordinary water-baths, as soon as the water evaporates a little, the platinum dish is left by the water and is merely exposed to the heat of the steam, which, in a vessel with a loose cover, does not amount to anything like ioo° C. In the second por- tion of the analysis, after the fat has been removed by means of the ether and alcohol, care should be taken, when the remaining casein and sugar with salts, are put in the platinum dish to be dried, pre- vious to the treatment with boiling water for their separation, that the drying is thorough. It is not necessary to continue the drying until the weight becomes absolutely constant, but the dish should be kept in the water-bath for at least three or four hours, as it will be found that the separation of the two elements is much easier, if the drying has been 20 INFANT FEEDING AND MILK ANALYSIS. continued a good many hours. Long drying ren- ders the casein almost absolutely insoluble; it becomes a hard, yellowish, horny mass, which will not dissolve even in a strong solution of caustic soda. The effect produced in different specimens of human milk, when the ether and alcohol have been added and the liquid agitated as described, is by no means uniform. There is always, after the bottle has been set aside for a few minutes, the clear ethe- real solution of fat on top, and this may be more or less yellowish in hue. It may be said here that the color of neither human nor cows' milk is a test of its richness in fat, for it is often found that a very pale milk will contain a large amount of pale fat, while, on the contrary, an unusually yellow milk may not contain more than the average amount. In the lower stratum of liquid, however, the effect is variable, sometimes quite heavy coagula, much like those produced when cows' milk is subjected to the process, are at once seen, which settle to the bottom in a thick, white, cheesy-looking mass, leaving a slightly colored fluid above, with perhaps a few minute curds sticking to the sides of the glass vessel and at the top of the lower stratum of liquid. Again, the coagulation takes place in the form of a very fine net-work, which can be distinctly seen through the sides of the glass, and which either remains sus- pended or sinks to the bottom only very slowly. Sometimes, when the net-work appearance is very marked and no heavy coagula at all have been pro- METHOD OF ANALYSIS. 21 duced, the solid portion remains permanently evenly- distributed through the fluid, from the lower part of the ethereal solution, where the meshes can be dis- tinctly seen, if the fluid is set in gentle motion, to the bottom of the bottle. Even after days, there may be no disposition to the formation of a sedi- ment. The effect produced reminds one strongly of the appearance of a dishful of fine soap-bubbles, except, of course, that the meshes of the net-work in milk are infinitely smaller, and are permanent, and filled with a liquid instead of air, as in the case of the soap-bubbles. Why this difference in the coagu- lability exists, when milk is exposed, under the same circumstances, to the action of fixed quantities of the same reagents, cannot at present be explained. The same difference in the coagulation has been noticed in examining by the same process the artificial food presently to be described. It isnot due wholly to the amount of the coagulable element (casein), for it has often been found that a specimen which showed the fine net-work coagulation contained an average quan- tity of the coagulable element when the analysis was, later, finished. At present, as already observed, no satisfactory explanation of this phenomenon is at hand, but it does not seem unlikely that it is due, in some way, to the degree of alkalinity of the milk ex- amined. The method suggested possesses many advan- tages ; the water and ash are determined by the old processes ; the mode of separating the fat, however, is a new one, and is susceptible of rapid application, 22 INFANT FEEDING AND MILK ANALYSIS. and is more exact than the old way of extracting it with ether from the solid residue. The amount of fat in any given sample of milk can be determined in at most from half an hour to an hour. The idea of separating the fat by means of ether and alcohol was suggested by the perusal of an article by Ed. J. Hallock {American Journal of Pharmacy, Octo- ber 1, 1874). The use of the reagents in the pro- portions suggested by him, however, fails to effect the purpose, as any one can see who will try the process ; for the oil-globules are set free instead of being dissolved in ether, as happens when the pro- portions recommended are used, and they only par- tially rise to the top, many becoming entangled in the meshes of the coagulated casein and remaining thus distributed through the fluid. The method proposed also extracts the fat more perfectly than that used by chemists generally, of extracting it with ether from the dried residue. This has been proved by actual experiment, two samples of the same milk being taken, when the fat was extracted from the dried residue of 10 c.c. of milk, 270 milli- grammes only were obtained, whereas the ether- alcohol method gave 305 milligrammes. This dif- ference is large enough to be a matter of great importance whqre such small quantities are used, as is usually the case in milk analysis. The separation of the casein and sugar by simply dissolving the sugar in water and allowing the casein, which the drying has rendered insoluble, to go to the bottom as a sediment, and then pouring off the METHOD OF ANALYSIS. 23 clear solution, may seem a return to old and crude methods. Filters, however, are very objectionable in dealing with casein ; first, because they allow considerable portions to pass through them, and, second, because the filter often becomes so clogged with the fine particles that the sugar solution can no longer pass through, or passes so slowly that the substances are lessened in quantity by decom- position before the filtration process is completed. Filters, therefore, should be discarded as unfit for use in milk analysis. This subject, however, will be more fully discussed in a future chapter. The reason why five cubic centimetres are weighed out for the first portion of the analysis and ten for the second, instead of taking five and then ten grams, is because it affords an easy Way of man- aging the error which must always occur to a greater or less extent in every chemical analysis. When the amount of each of the elements has been deter- mined and the sum added up, it will usually be found that there has been a small loss (the error will sometimes be a slight amount in excess, owing to imperfect drying), and this may be disregarded, the sum being, by the simple rule of proportion, reduced to parts of one hundred. The amount of error may then be easily stated with each analysis ; and yet the analysis looks much better, and is much more easily managed, if it is thus made to appear exact. This seems, too, a perfectly fair method of statement of results, if the error is given in each case. The fol- lowing explains the method of calculation. After 24 INFANT FEEDING AND MILK ANALYSIS. finishing an analysis, the following weights were obtained : — Water . • 91-54 89.0380 + ' r 89.038 Fat . . . 2.48 reduced by 2.4122 -ji 2.412 Casein . .75 rule of pro- ■= 7294 + ► = - .729 Sugar . . 7.92 portion 7-7035 + 7.704 Ash . . .12 .1167+ J , -ii7 102.81 100.000 The weight of the 10 c.c. of milk used in the second portion of this analysis was 10.286 grams, which would make the weight of 100 c.c. = 102.86 grams ; the loss, therefore, was .05 gram. This multiplied by 100 and divided by 102.86, the origi- nal weight, to get the percentage, gives .048, which shows the error in the analysis to be a loss of forty- eight thousandths of one per cent. In cream analysis the method is invaluable, as it offers a means of checking, partially at any rate, any error, which may arise from imperfection in the dry- ing, which is the difficult part in analyses carried out by the old method; of extracting the fat with ether from the dried residue. Wanklyn {Milk Analysis, by J. Alfred Wanklyn) speaks of the " great diffi- culty of cream analysis," and says "there- is far more difficulty in drying a cream residue than in drying a milk residue," and further says that the whole experimental error, if there is any, " falls on the determination of the solids not fat, and that any imperfection in the analysis tends to enlarge the solids not fat." In analyzing cream, the same method should be followed as has already been suggested for the METHOD OF ANALYSIS. 25 analysis of milk, with three exceptions ; in the first portion of the analysis only one, or, at most, two grams of cream should be taken, instead of five cubic centimetres, as in milk analysis ; in the second portion, only five grams should be used, instead of ten cubic centimetres, as in milk analysis ; and, third, after the fat has been extracted, by agitation with ether and alcohol, the drying of what remains (the casein, sugar, and salts) should be continued until the weight becomes constant. This weight is, of course, that of solids not fat, and, when added to that of the fat which has already been extracted, should tally with the weight of the total solids . obtained by drying in the first portion of the analy- sis. In case these two weights should not tally, the probable explanation is, that in the first portion, the water has not been completely evaporated, for it is very difficult, or almost impossible, if the cream examined is very rich in fat, to obtain a correct weight of the total solids by simple drying in the water-bath. If condensed milk is to be analyzed, the method should be carried out in the same manner as has already been described, except that in the first part of the analysis only half a gram should be used, and some alcohol mixed with the condensed milk, after the quantity has been weighed, as this seems to facilitate the drying. In the second portion, two grams should be taken instead of ten, as directed when fresh milk is to be analyzed. 3 CHAPTER II. STATEMENT OF RESULTS OF ANALYSIS AND COMPARI- SON OF HUMAN AND COWS' MILK. Analyses of human milk, carried out as advised in the previous chapter, seem to show that it never contains the amount of casein commonly supposed, and that in other respects, also, its composition is different from the idea commonly held. Instead of containing two to four per cent, of casein, as is generally supposed, it contains only one per cent. While containing, however, a much smaller amount of casein than cows' milk, there is a larger quantity of sugar and less inorganic matter. The difference between the relative amounts of water and fat is not very great, there being nearly equal quantities of fat and a slightly greater amount of water in human milk ; but the difference is very slight, amounting only to one or two per cent. This may be seen by examining Table VIII, page JJ, in which different analyses are placed in parallel columns for compari- son, and it shows human milk to be very different from what it is ordinarily supposed to be, and from cows' milk. The analyses of Vernois and Bec- querel, which are widely known and much quoted, and of Simon, are almost identical with what cows' milk is now known to be, and therefore they can- not be correct. These analyses are accepted as 26 RESULTS OF ANALYSIS AND COMPARISON. 2J standard by such well-known authorities as Car- penter, Kirke, Marshall, Edward Smith, Kehrer, and Gorup-Besanez. It is curious how all previous ex- perimenters and writers upon milk agree that human milk contains less casein than does cows' ; and yet, when the actual question of the relative composition is arrived at, the mean of Vernois and Becquerel is used as the standard, although their estimate of the quantity of casein is quite as large as the amount granted to be contained in cows' milk. The observation of the author, therefore, that human milk never contains more than about one per cent, of casein, is an original one ; for, although Henri and Chevallier, and other investigators, long ago arrived at nearly the same analytical results, yet none of them ever enunciated the belief that human milk contains always the small amount of casein, and never three or four per cent., as com- monly supposed, thereby denying the correctness of the analyses commonly accepted as standard. Much has been written of later years, and many experiments have been made, to prove the difference in chemical composition between the casein of cows' and of human milk. Kehrer made an ingenious experiment, separating the coagulum of milk from the serum by forcing the serum through a porous cell by means of an air-pump, and endeavored therefrom to prove that the difference between hu- man and cows' milk lies principally in a difference in the composition and chemical reactions of the 28 INFANT FEEDING AND MILK ANALYSIS. two kinds of casein. At the same time, he says the two serums are alike in their reactions, and makes no mention of the great difference in the amounts of casein. Biedert has written a valuable and much quoted article to prove that the caseins of the two milks are essentially, and in their nature, unlike. Both Kehrer and Biedert fail, however, to emphasize the great and cardinal difference — that there is only one-third the quantity of casein in human that there is in cows' milk. Casein is, in its nature, akin to al- bumen, and the different effects produced when albu- minous urines containing different quantities of albumen are boiled and treated with nitric acid are commonly known and understood. If the amount of albumen is small, the coagulation takes place in the form of a mere opalescence of the fluid; the coagula are individually so small that they cannot be seen ; whereas, if the amount of albumen be large, the coagulation takes place in heavy white flakes, which are individually easily visible to the naked" eye. There is no reason why a parallel explanation of the different coagulability of the two milks should not hold good — that the one contains much less coagulable matter than the other, rather than that some far-away difference should be sought for in the chemical composition of the casein. While it is true that the great and cardinal difference between human and cows' milk is in the relative proportions of casein contained, it cannot be denied, that there is strong reason to believe that a difference exists (it is impossible, in the present RESULTS OF ANALYSIS AND COMPARISON. 29 state of our knowledge, to know how great Or how little, and of what importance it may be) between the two sorts of casein ; still, this has been given an undue weight, and the great difference in relative quantity, lost sight of. Whatever may finally be proved as to the parallelism or difference of the two sorts of casein, it is indisputable that the casein, which is the coagulable element, is the indigestible portion of cows' milk when used as an article of food for the human infant. The most important end to be sought for as a result of analysis is to acquire a correct and exact idea of the average composition of the substance analyzed. Therefore, it is necessary to have, before drawing deductions with regard to human milk, or comparing it intelligently with the milk of the lower animals, a scientifically correct understanding of its general average composition. This can only be had by analyzing the milk of a large number of women, under different circumstances and obtained at all sorts of times ; for it is a well-known fact that in cows, the first milk drawn from the animal is much poorer in fat than that which comes last in the milking, or, as it is commonly called, the " strip- pings." Why this should be so does not seem ever to have been satisfactorily explained, but that it is a fact, and that it holds good with regard to women as well as cows, is beyond dispute. This consti- tutes one among the various difficulties in obtain- ing a correct mean of the general composition. The process of analysis which has been recommended, 30 INFANT FEEDING AND MILK ANALYSIS. also, is such a tedious one, taking four to six days to complete a full proximate analysis, that the time required to finish a large number would necessarily be very great. It was suggested that the same or even a more accurate result would be attained by taking equal quantities of the milk of many women and mixing them together, and then analyzing. By this process a correct idea of the average composi- tion would be acquired, and only one error intro- duced ; whereas, if separate analyses were made, and then an average taken, there would, of course, be the same number of errors introduced as there were analyses made ! Gerber has recommended that in analyzing human milk the woman should be made to pass two or three hours without nursing her child, and then to draw as much as can be obtained into a vessel, and this, after careful mixing, used for analytic purposes. He says that from thirty to two hundred cubic centi- metres will usually be obtained, and that both breasts should be drawn. This may be good advice, but it is difficult to follow, for in many women but little milk can be obtained, either by the use of a breast-pump or by milking it out with the finger and thumb, even when the child evidently has no difficulty in obtain- ing an abundant supply so soon as it is put to the breast ; and besides, but few women, except paupers, will submit to have their whole supply taken from them, for there is then nothing left for the infant, and it will have to wait several hours, crying, until a fresh accumulation can take place. The milk, therefore, RESULTS OF ANALYSIS AND COMPARISON. 31 which was used in making the analyses in the accom- panying table (Table III) was obtained at all sorts of times, and no attempt was made to draw the TABLE I. MILK OF TWENTY-SEVEN WHITE WOMEN IN ALMSHOUSE, OBTAINED MARCH 23, 1882. Mother's Child's Number of Age Age Children Reaction. (Years). (Months). Woman had had. 29 23 3 I Alkaline. 3 2 23 5 2 22 5 I 19 3 2 18 9 I 18 3 I 22 2 . I 25 12 3 27 6^ 1 23 6 1 33 4 6 ' 22 S 1 - 25 1 1 24 17 1 23 1 2 22 16 1 24 3 [ 30 6 1 33 1 1 37 2 7 18 14 1 34 21 2 2 5 16 1 37 2 12 38 4 1 23 20 1 whole supply of milk from the breasts of any one of the women. Where single analyses were made, the usual rule followed was to tell the woman to put 32 INFANT FEEDING AND MILK ANALYSIS. her child to the breast for a minute or two to get the milk started, and then to draw into a clean bottle about twenty or twenty-five cubic centimetres. This gave neither the first milk, which is poor in fat, nor the rich " strippings," which come last. When the mixed milk of several women was used, as in the case of that obtained from the Philadelphia Hospital, it was taken simply by going into the ward and making each woman give five cubic centimetres of milk, and then thoroughly mixing the whole TABLE II. MILK OF ETGHT NEGRO WOMEN, OBTAINED MARCH 23, 1882. Mother's Age (Years). Child's Age (Months). Number of Children Woman had had. Reaction. 20 5 I Alkaline. 21 12 I ' 43 28 18 11 24 18 2 2 t 21 2 2 ' 22 3 3 t 22 13 2 (c together. In this way, some of the women had just nursed their children, some had allowed an hour or two to pass since the child had been to the breast, and others were midway between two nursings. This method would seem, as the women were taken in all possible stages, to give as fair an average as can be obtained of the usual composition. Table I shows the ages of the women, the ages of the infants, the number of children the women had had, and the RESULTS OF ANALYSIS AND COMPARISON. 33 reaction of the milk, in an analysis of the milk of twenty-seven women in the Philadelphia Hospital, and Table II shows the same thing in the anal- ysis made of the milk of eight negro women ob- tained from the same source. These specimens were kindly furnished by Dr. Fairfield, the resident physician, and were obtained by the permission of Dr. John M. Keating, the visiting physician in charge at the time. It will be noticed that in every instance (see Table III) in which the reaction was taken with test-paper the milk was alkaline except one, and that was neutral. It is a fact, and one not generally known, that fresh human milk will almost always turn litmus- red paper back to blue again, and cows' milk almost as universally turns litmus-blue paper red. When the milk of the twenty-seven women was obtained at the hospital, Dr. Fairfield got also that of another woman, who was suffering with syphilis, and found it to be markedly acid, and, therefore, it was thrown out as not being a fair sample of healthy milk. If it be desired to analyze cows' milk, the same process, already so fully described, should be used, and the result will show a larger proportion of in- organic matter (ash), less sugar, and a much greater amount of casein, while the quantities of fat and water will not be found to differ very materially from those existing in human milk. The details of the analysis of cows' milk by this process are much less trying, and it takes less time than when human milk is analyzed ; for, as the casein is in 34 INFANT FEEDING AND MILK ANALYSIS. W pa O H Average from Milk of the 43 Women. co COM3 i>. h- vOQO tJ-O O *: *i °. "t w . 00 No. 10. Lower Class, aet. 28 Years, 2d Child, set. 2 Mos. 00 oi i>. CO .215 per cent, loss. No. 9. Lower Class, -aet. 26 Years. 3d Child, aet. 20 Mos. . 00 8 .078 per cent, loss. No. 8. Lower Class. Alkaline. 0\mM TJ-00 OO H l^M M OO ro r- CO .078 per cent, loss. No. 7. 8 Negro Women in Alms- house. See Table II. aw h 000 CT\ tt" I*- 0\ Os co c\ ^ q CO 6 .157 per cent, loss. No. 6. 27 White Women in Alms- house. See Table I. CO 0\00 r-»co COCO ""> 1 C\ °. ^ 9 "1" °. CO 6 .166 per cent, loss. No. S . Ameri- can, Better Class. Alkaline. >o 00 co\© r— O O\00 ON "-« 00 8 No. 4. Ameri- can, Better Class, aet. 30 Years. Child 10 Mos. h iriN onoo O "tf-oo \o ON oonoo ro o\ " rC CO 8 8 14 No. 3. Scotch Woman, Lower Class, aet. 36 Years. Child 10 Mos. Neutral. q rt- r>. i>. im 00 .04S per cent, loss. No. 2. Ameri- can, Lower Class, aet, 25 Years. Child 6 Mos. Alkaline. lONOOOO N O\Q0 co<£) 1 ^DvO 0>lr1H r^. to " tC * 00 ci j-i u i-. QJ O No. 1. Irish Woman, Lower Class, set. 30 Years. Child, 15 Mos. Alkaline. >o 00 VO O r^.'O oi to w CO 2 " 14. ..II. 782 Sugar 4.I40 4.308 ' ' 4. ..12.470 " 15. ..18.519 Ash ■457 •475 ' ' 5-I7-I29 ' 6. ..16.024 " 16. ..21. 465 Total.... 100.000 100.000 ' ' 7. ..13.825 ' 8. ..14.950 Average percentage from the 17 esti- mates. .109 .039 per '< ' 9. ..18.082 per cent. cent, in ' ' 10. ..16.502 16.398 loss. excess. ' * 11. ..12.159 Table VI shows the results of two full proximate analyses of ordinary cream, and the percentage of fat in seventeen specimens of cream, such as is sold in the city, taken at random from different milk and cream venders. The cream amounts in the full proximate analyses are included in the sev- enteen fat percentages, being Nos. 3 and 4. CHAPTER III. PROOF THAT HUMAN MILK CONTAINS ONLY ABOUT ONE PER CENT. OF CASEIN. / Although many chemists have made analyses of human milk, and a great variety of divergent re- sults have been attained by different methods, there has, as yet, been no proof offered of the correct- ness of any of them. This constitutes an important missing link in any attempt to place the question of the composition of milk upon a settled basis ; and if a method of analysis is ever devised that will give results which shall be universally accepted, and stand the test of time, the accuracy and correct- ness of the method must be susceptible of proof — simple, scientific, and incontrovertible proof. To prove the correctness of the analyses already given, will be the object of this chapter. No one disputes that in ether, chemists have a perfect solvent for fat, which, when properly applied in milk analysis, extracts it all. The fat, when sep- arated, can be seen, and the eye tells positively that it is fat. With regard to the water, it is equally certain that by the evaporation process its amount can be accurately estimated. This statement is made with the knowledge that there may be with the water some slight traces of other fluids — alcohol, for in- 38 AMOUNT OF CASEIN IN HUMAN MILK. 39 stance, and, perhaps other volatile liquids; but these must be in such minute quantity that they need not be taken into consideration ; and, for the present, the liquid portion of milk may be spoken of as the water. It is equally certain that in inciner- ation, properly performed, there exists an easy and correct method of determining the amount of inor- ganic matter. In the future, of course, there may be perfected some way of estimating the salts in milk, by extracting from the liquid milk, or from the solid residue left after evaporation ; and this may show them to exist in larger quantity than the pres- ent method of incineration leads to believe ; but the possible error introduced in this way must be very small, and does not invalidate the general facts stated. That the existing estimates of the water, fat, and inorganic matter are correct, is further proved by the fact that there is no difference of opinion in regard to their amounts. Examination of the analyses of different chemists shows an almost exact uniformity of conclusion with regard to the relative quantities of the above-mentioned substances. When the estimates of the casein and sugar, how- ever, are considered, the widest divergence of view is discovered in the conclusions as to the amounts existing in human milk. In regard to cows* milk, chemists all arrive at nearly uniform conclusions. The casein in human milk is estimated by Dolan and Wood, in one of their analyses, at 7.005 per cent. ; Vernois and x Becquerel give it as 3.924 per 40 INFANT FEEDING AND MILK ANALYSIS. m <: "lin^uSa'jj q\ CTv CO 4 CO CO '3UU3A3n£) q ro vO CO 00 •usAbj M 00 00 o q 'S3l3J^[ vo t-. ^ o q •*■ ro 00 ■^P!X CO **• CO N in. vq CO 4 oo •IUU13J3 CO OO CO 1-1 CO 4 lO vq •3jaAo(j 00 CO 00 '-^PI-^H/T o CO OO ■u3[pre H M CO CO 4 ■P°°M. PUB UB[0{J IJ-J t-H o « O On q\ OO •J3IflKA3tQ pUB UU3f£ M O N O CO •uouiig CO N - o "« s 1 E rf ej O >v ■2 3 * 5. » 2 "ft • 3 3 ?! £ p.-S 2 tJ ft *- J 3 ft 3 _a> „ Tl JU •W W « O e Vw -J* "^ -O o J? o $3 [fl a, pi •3 S C3 o H O 5" - « t- a 8 0) Id o 3 c < * r AMOUNT OF CASEIN IN HUMAN MILK. 41 cent, and Henri and Chevallier as 1.52 per cent., while the original analyses already quoted seem to show that there is about 1 per cent. Now, the fact is a striking one, that if, in any of these analyses, the sugar and casein amounts be added together, the sums are found to be in each instance nearly the same. Table VII shows this to be the case. The table also shows that in each instance where the casein amount is large, the sugar is small, and vice versa — that where the casein amount is small, that of sugar is large. It has been already said that, as regards the anal- ysis of human milk, all observers are agreed as to the proportions of the water, fat, and ash ; it is now further evident, from the table, that all agree as to •the quantities of casein and sugar taken collectively, and that only when the separation of the two is attempted does there exist any difference of opin- ion. The separation of the casein from the sugar, therefore, is the difficult part of milk analysis, for in regard to this alone is there any difference of opinion. In this portion of milk analysis, then, is reached the stumbling-block, and it alone requires any explanation, for the rest is univer- sally conceded, and cannot therefore but be con- sidered as already placed upon a scientifically exact basis. There are but two possible explanations of the different results arrived at by various investigators ; one, that human milk is as variable a substance in regard to the amounts of casein and sugar contained 4 42 INFANT FEEDING AND MILK ANALYSIS. as the different analyses would lead to believe ; and the other, that the methods of the majority of chem- ists have been faulty and their conclusions incorrect. That the second of these two explanations is the correct one, does not admit of doubt. Wanklyn says that cows' milk is a substance exhibiting great uniformity of composition, and what he says of cows' milk is also probably true of human milk. There is no reason to expect that it would vary so much in regard to the proportions of casein and sugar, when cows' milk exhibits such uniformity of composition in these respects. It may, by analogy, be fairly argued that human milk is very unlikely to be so variable as published analyses would seem to show. The proof of this, however, lies in show- ing, by examination of a large number of speci- mens, that human milk always contains a large amount of sugar (say seven per cent.) and therefore by exclusion, it cannot contain the great amount of casein it is usually credited with, for all observers agree as to the sum of the amounts of the two sub- stances. The existence of this large amount of sugar in hu- man milk, it was attempted to demonstrate by exper- imenting as to how much could be obtained in the crystalline form from any fixed quantity, and then, by applying the same process to cows' milk, to find out whether an equal or, as should be the case if the already published original analyses are correct, only a less quantity of sugar will take the crystal- line form. AMOUNT OF CASEIN IN HUMAN MILK. 43 An experiment was made as follows : 10 c.c. of human milk, which had already, by the process described, been found to contain 7.224 per cent, of sugar was, as usual, agitated with ether and alcohol, and the fat removed. After the removal of the fat the remaining portion was carefully washed into a dish, and in the water-bath, at a temperature of 70 to 8o° C, evaporated until only about 10 c.c. of fluid remained ; upon this was poured a mixture of 25 c.c. of water with 25 c.c. of alcohol, and the whole allowed to stand over night. By morning a precipitate had formed and settled to the bottom of the vessel ; this was thrown upon a filter and washed with a mixture of equal parts of boiling alcohol and water. The filtrate was again reduced in the water-bath, at a temperature of jo° to 8o° C, to about 10 c.c, and then 75 c.c. of absolute alcohol added. This caused again the formation of a slight precipitate, which was allowed to thoroughly settle to the bottom, when the perfectly clear fluid above was poured off into a dish, care being taken that none of the precipitate passed over with the clear fluid. This liquid was allowed to evaporate, with- out heat, in an open dish of known weight, and there remained, finally, only crystalline milk-sugar, with a very minute amount of the inorganic ma- terial. The IO c.c. of milk thus treated yielded 659 milligrammes of sugar dry at 100° C. This milk had been previously ascertained to contain 738 milligrammes of sugar to each 10 c.c, whi^ph made its percentage of sugar 7.224, as already stated. 44 INFANT FEEDING AND MILK ANALYSIS. That all the sugar which existed in the 10 c.c. of milk was not obtained (nor was such a thing at- tempted), is proved by the fact that if a concentrated solution of milk-sugar in water is treated with an excess of alcohol, the precipitation of a considerable quantity of sugar takes place ; and this occurs in proportion as the original sugar solution is concen- trated, and the amount of alcohol added large. This fact, which is easily demonstrated by making a solution of crystalline milk-sugar in water and then treating with alcohol, of course occurred in the above-described process, some of the sugar falling with the casein when alcohol was added, as was done twice ; and, therefore, the clear fluid poured off from the precipitate did not contain all the sugar, but some remained behind in the solid form with the casein. The figures given are sufficiently nearly parallel to prove the point, for, by the method of crystal- lization described, it was not expected that all the sugar present would be obtained. The effort was made merely to obtain it pure, and in sufficient quantity to prove that the sugar existed in the milk in the large quantity shown by the analysis, and therefore necessarily, by exclusion, the existence of only the small amount of casein. The demon- stration thus obtained seems incontrovertible, for when the existence of the large amount of sugar is shown, it follows as a necessary corollary that there can be only the small amount of casein. As a means of further proving that the sugar ob- AMOUNT OF CASEIN IN HUMAN MILK. 45 tained by crystallization, as described, was entirely free from any traces of casein, it was tested by Mr. J. K. Hecker, the apothecary of the Pennsylvania Hospital, by the Nessler test described by Wank- lyn and Chapman {Water Analysis, by J. Alfred Wanklyn and Ernest Theopron Chapman, London, 1876, p. 25), This test decomposes the casein and forms ammonia from the nitrogen. When the crys- talline sugar was subjected to its action, it showed it to be practically free from casein. Cows' milk, when subjected to the same process of precipitation of the casein by alcohol, after the removal of the fat, yielded only about four or five per cent, of crystalline sugar. The manipulations were not carried out with the same exactitude as when human milk was examined, for there is no dispute as to the amount of sugar in cows' milk ; the ex- periment was therefore made merely to afford con- firmatory evidence of what was shown by that upon the human milk. For if only a little more than four per cent, of sugar existed in /human milk, as is claimed by Vernois and Becquerel, and others, and this being the quantity universally conceded to exist in cows' milk, then, both being subjected to the action of the same reagents, the same amount only of crystalline sugar should be yielded. This, however, was not the case. One of the strongest proofs of the correctness of the estimates of fat in milk is afforded by the fact that after it has been separated, it can be seen, and 46 INFANT FEEDING AND MILK ANALYSIS. the eye tells that it is fat. When sugar is crystal- lized, can be seen and felt, and examined with the microscope or a magnifying-glass ; the characteristic- ally shaped crystals of milk-sugar are seen, and the fact that it is sugar, and nothing else, becomes self- evident. To test still further the accuracy of the method described, a specimen of human milk was analyzed and found to contain the different proximate con- stituents in about the usual quantities. There were then separated from a further portion of the milk, taken at the same time and under exactly parallel circumstances, fresh portions of the casein and sugar, which were given to Mr. Hecker to test their purity — the sugar to be subjected to the Nessler test, to discover if it contained any casein, and the casein to be subjected to the action of Fehling's test, to find whether or not it was free from all traces of sugar. The casein entirely failed to produce any effect upon the copper solution, thus showing that it was free from sugar, while, if a small portion of the sugar was added to the solution, the charac- teristic reduction of the copper at once took place, When the sugar was subjected to the Nessler test, .05 gram being introduced into the retort when the decomposing materials were ready, it almost entirely failed to react, showing no more change than would be accounted for by the distilled water which had been used to prepare the reagents. This distilled water must have contained traces of organic matter, AMOUNT OF CASEIN IN HUMAN MILK. 47 for when it was subjected to the test it showed slight traces of ammonia. The test is so delicate, that it is only by the greatest care and nicety in preparing the materials that they can be had per- fectly free from all nitrogenized materials. The conclusion was that the sugars — both that prepared by the ordinary process advised for analytic pur- poses, and that obtained by crystallization — were, practically speaking, free from casein. One of the strongest corroborative evidences of the correctness of the low estimate of the casein in human milk is that when cream, milk, water, lime- water, and milk-sugar are mixed together in pro- portions presently to be described, the resulting mixture is, in its appearance, taste, and reactions, strikingly like human milk ; much more so than any of the other mixtures recommended as infant foods. This mixture is known to contain fat, casein, milk- sugar, and water in the same proportions as the analyses of the author seem to show that they exist in human milk, for it is fair to assume as known quantities the proportions of the various constit- uents in cows' milk and cream, and these being known, it' is easy, by arithmetical process, to con- struct a mixture which shall contain the various constituents in any desired amounts. That this mixture should react, when subjected to the same process of analysis that has been recommended for human milk in an almost exactly similar manner, is certainly very striking, and tends, at least, to show that the liquids are nearly identical. 48 INFANT FEEDING AND MILK ANALYSIS. If, then, it has been shown that human milk contains approximately 87.1 per cent, of water, 4.2 per cent, of fat, 7.4 per cent, of sugar, and 0.1 per cent, of inorganic matter, the proof that it contains, not three or four per cent, of casein, as is commonly taught, but only about one per cent., is complete. CHAPTER IV. OBSERVATIONS UPON METHODS OF ANALYSIS HERE- TOFORE PURSUED. The best known analyses of human milk are those of Vernois and Becquerel, and their results have been accepted as standard by most writers upon physiology and foods. A full account of their methods and results is contained in the Traite de Chimie Pathologique, par Becquerel et Rodier, Paris, 1854, at page 393. The original article will be found in the Ann. d'hyg., p. 257. In attempting a criticism of the methods pursued, that of Vernois and Becquerel will first be discussed, as their mean has been so widely quoted and is the result of eighty-nine analyses of human milk made by them. In pursuing their method, the milk to be analyzed was divided into two equal portions ; from the first they estimated, in the usual manner, the amount of water by evaporation, the total solids by the residue left, the fat by extracting with ether from the dried residue, and the inorganic matter (ash) by inciner- ation ; so far, therefore, their results coincide accu- rately with those of almost all other authorities. When, however, the second portion of the analysis — the separation of the casein and sugar — is reached, they direct that thirty grams of milk be taken and curdled by heating to the boiling-point, after adding 49 50 INFANT FEEDING AND MILK ANALYSIS. one or two drops of rennet and a few drops of acetic acid. This is filtered, and the clear filtrate, they say, constitutes the serum, which consists of the sugar, extractive matters, and soluble salts. The amount of sugar in this serum was then estimated by means of the "polarimetre."* This gives, they say, the exact quantity of sugar contained in the thirty grams. If this process is carried out, it is found that the milk does curdle, to be sure, but the coagulum, which contains much the larger part of the fat (none of which has been previously removed) as well as the casein, is of such a consistency that the moment it is thrown upon a filter it seems to fill all the pores of the paper, and nearly twenty-four hours are required to complete the filtration process. This, of course, makes it quite impossible to wash the residue left upon the filter, for if the attempt is made to pass any water through the mass of coag- ulum upon the paper, twenty-four hours more would be required, and during that time fermenta- tion would have occurred to such an extent as to entirely vitiate the results acquired. Fermentation is very apt to have begun, even when no attempt at washing is made, before the liquid has all drained through the paper, and must, to some slight extent, therefore, vitiate the accuracy of the results. Hav- * " Pour conn&itre la quantity de sucre, on soumet le s£rum au polarimetre, et en etudiant le degr£ de deviation du rayon polarise et recherchant sur une table constitute d' avance, sa deviation, on a la quantity exacte du sucre de lait contenue dans iooo grammes de scrum du lait." OBSERVATIONS UPON PREVIOUS ANALYSES. 5 I ing by these processes obtained the weights of the sugar, fat, etc., that of the casein is estimated by difference. The fallacy of this process is, that during the long time which is required to effect the separation of the coagulum from the matters remaining in solu- tion, by passing the latter through a filter- paper, a considerable portion of sugar crystallizes upon the paper, more is entangled in the coagulum, which, as has already been said, it is impossible to wash ; and thus the serum which is finally obtained, does not contain all the sugar, quite a large portion of which has remained with the casein upon the filter, and is, therefore, classed with it as casein. Further, the expediency of estimating by difference any element in making an analysis of an organic substance is very doubtful, as being likely to lead to error. If by any means it can be effected, each element should be individually separated, so that it may be seen and felt, and the fact of its being the substance supposed, thoroughly established by testing. The use of so large an amount of milk as thirty grams for evaporation and estimation of the total solids and water is also inadvisable. Simon* opens his article upon milk by saying, " Perfectly fresh milk has always a decidedly alkaline reaction, and it retains this property for a longer or shorter time : the milk of women retains its alkaline reaction longer than that of cows, etc." That this is not * Animal Chemistry, etc., by Dr. J. Franz Simon. Sydenham Society Translation. 52 INFANT FEEDING AND MILK ANALYSIS. true of cows' milk, the author has proved by testing with litmus paper the milk of about thirty healthy cows, one evening, at a locally famous dairy farm. The milk was drawn directly into a vessel from the teat and immediately tested, and in almost every instance it distinctly reddened the test-paper. In one or two cases only the color of the paper remained unchanged, and further testing with turmeric paper yielded also negative results, showing that the milk was neutral . in reaction ; but in no single instance was there the slightest evidence of alkalinity. Simon estimates the water and total solids, as usual, by evaporation, and then extracts the fat from the dried residue with boiling ether. The remaining portion is pulverized and digested with a little boiling water, and the solution evapo- rated at a gentle temperature to the consistence of a thin syrup, when it is treated with ten or twelve times its volume of alcohol of 0.85 per cent., which precipitates the casein, and with it, as he justly observes, some of the sugar. This manipulation is repeated once or oftener, and, finally, the casein dried. Simon himself was not well satisfied with the results thus obtained, for he says : " This analy- sis of milk does not yield, as Berzelius justly observes, any very accurate results, etc." The fallacy of this method is caused by the fact that milk-sugar is entirely insoluble in absolute alco- hol, and only can be dissolved in alcohol as it becomes dilute, and further, because, as Simon him- self says, if a concentrated solution of milk-sugar OBSERVATIONS UPON PREVIOUS ANALYSES. 5 3 in water is treated with alcohol, a precipitation of the sugar is caused. This fact renders it impossible to know, if the method of Simon is pursued, when all the sugar is removed from the precipitated casein. The original article of Chevallier and O. Henri has not been accessible to the author, but an account of their method and results is given by Simon.* They precipitated the casein with acetic acid and estimated the sugar by evaporation of the fluid portion, and then by incineration determined its amount, the loss in burning being set down as the amount of sugar. Simon does not say how the separation of the fluid portion from the precipitate was effected, but it must probably have been by filtration; and this, if true, would account for the fact that their estimate of casein is slightly too high. If fluid milk is curdled with acetic acfd, and then an attempt made to filter off the fluid portion, it will be found, as has already been said, that the coagu- lum, which consists almost wholly of fat and casein, is of such a consistence that when it is put upon a filter-paper it soon stops the pores of the paper, so that filtration takes place only very slowly. As evaporation goes on to a considerable degree, the portion of the filter-paper above the liquid is by capillary attraction kept constantly soaked with the solution of sugar, and gradually a good deal of sugar is left upon the upper portion of the paper, * Loc. cit. 54 INFANT FEEDING AND MILK ANALYSIS. and some also is entangled in the coagulum. All this sugar is, in the final calculation, classed with the casein. The error, however, thus introduced is small when compared with that of other methods, and consequently the analysis of Chevallier and Henri is more nearly correct than any heretofore published. Their analysis is the one which has been accepted by Lethby* as his standard of the composition of human milk. It is with great hesitation that a criticism Of the process of analysis of Wanklynf is approached. The method suggested by him is the best, and offers more nearly accurate results than any other as yet published, and has, so far as the analysis of cows' milk is concerned, been a great step in advance in the effort to arrive at an exact knowledge of the composition of milk. That almost all chemical processes are'susceptible of improvement is, however, a fact that is indisputable, and that suggested by the author, although it is believed to be an advance upon the old methods, will, in its turn also, doubtless be cast aside for some other one still more easy, rapid, and accurate. Wanklyn, in his treatise, con- fines himself to the consideration of cows' milk, but the fault that may be found with it as a means for the examination of cows' milk also holds good when it is applied to human milk. His method of extracting the fat from the dried residue with ether is the same as has been pursued by others, and it * On Food, etc., by H. Lethby. London, 1870. f Milk Analysis, by J. Alfred Wanklyn. OBSERVATIONS UPON PREVIOUS ANALYSES. 5 5 gives, if carefully carried out, fairly accurate results, but is much more tedious and troublesome than the method suggested by the author ; besides which, if the fat is extracted from the liquid milk and the remainder then dried, it renders much more easy the subsequent separation of the casein and sugar, and there is less risk of loss, as the amount of necessary handling is much reduced. Wanklyn says of the separation of the casein and sugar, that it should be effected "by extracting with strong alcohol, and ultimately adding a little boiling water, so as in effect to extract with very weak hot alcohol, the milk-sugar, and the soluble part of the ash, i. e., the chlorides, will pass into solution." The sugar is estimated by evaporating to dryness and then incin- erating, the los's in burning being the weight of the sugar. The separation of the solution from the undissolved casein is effected by filtration. This method is open to criticism, for two reasons. First, because milk-sugar is almost totally insoluble in strong alcohol, and therefore alcohol is perfectly useless in dissolving out the sugar from the residue, unless it is used because its presence is supposed to prevent the casein going into solution with the sugar ; for the sugar is dissolved, not by alcohol but by the water with which it is diluted. It will be found, also, that if it is attempted to dissolve milk- sugar in a liquid containing any but a very small amount of alcohol, the solution will take place only very slowly ; and this might easily be anticipated, when it is recollected that alcohol will cause milk- 5 6 INFANT FEEDING AND MILK ANALYSIS. sugar to precipitate when it is mixed with a watery solution of the sugar. This being so, the attempt to separate the casein and sugar with dilute alcohol is very likely to cause error by some of the sugar remaining behind undissolved with the casein. Second, as the final separation of the solution from the solid residue is directed to be effected by filtra- -tion, the sources of error already mentioned in connection with the observations upon the method of Chevallier and Henri are liable to be fallen into ; and further, all paper filters will allow quite a con- siderable portion of the casein which has coagulated in fine particles to pass through. This observation is confirmed by one recently made by Dr. F. P. Henry,* that if blood was thrown upon an ordinary filter- paper, even when a very small quantity was used, about one-third of the red corpuscles passed through and were found in the filtrate. This was estab- lished by a careful use of the haemacytometer, the number of corpuscles being counted both before and after filtration, when it was found that one-third of the number originally present had passed through the paper. If filter-paper will allow blood corpuscles to pass through its meshes, it surely cannot be depended upon to prevent the passage of the finer particles of coagulated casein. The possible error involved in following the method of Wanklyn is, after all however, very small, and infinitely less than that introduced by * Archives of Medicine, October, 1882. A Contribution to the Study of Ansemia. OBSERVATIONS UPON PREVIOUS ANALYSES. 57 most other analysts, and it amounts merely to causing a slightly too large estimate of the casein at the expense of the sugar. Many analysts of milk have estimated the amount of sugar by the copper test, using Fehling's solu- tion. The results obtained in this way by different investigators are so various that it is impossible they can all be correct, and a large part of the divergent conclusions attained must be set down to error. It would be absurd at this day to attempt to cast any doubt upon the value of the copper test, both as a means of qualitative and quantitative esti- mation of sugar ; but when it is introduced into new fields, and there is no means of correcting the re- sults acquired, it alone having to be depended upon to decide the amount of one constituent, and another which is in intimate admixture or solution being estimated by difference, the results should be scru- tinized with great care and only accepted with ex- treme caution. When, however, different analyses of human milk are examined, the estimates of the sugar and casein — for, as has already (pp. 39-41) been so carefully shown, it is upon the amounts of these two elements alone that any difference of opinion exists — arrived at even by the same author in differ- ent analyses, are so widely apart that, if the truth of Wanklyn's observation as to the uniformity of com- position of cows' milk applies at all to human milk, all cannot be correct. Dolan and Wood* give thir- * The Practitioner for February, March, April, and May, 1882. Article upon Human Milk. 5 5 8 INFANT FEEDING AND MILK ANALYSIS. teen original analyses of human milk, and in one they set down the amount of casein at 7.005 per cent, and that of sugar 1.921 per cent, in another the casein is 3.603 per cent, and sugar '4.507 per cent. In these analyses the sugar amount is taken by the use of the copper test, and then the casein esti- mated by difference. If the estimates are correct, and milk is really so variable a substance as they would seem to prove, analysis, as a means of under- standing its composition and of helping toward a conclusion as to how best to artificially feed infants, had better be abandoned ; for it will be quite impos- sible ever to make a food like a substance, different specimens of which are more unlike than the milks even of any two of the lower animals are represented to be. The copper test is so delicate, and such various directions are given as to the exact manner for using it, that, as such different estimates of the amount of sugar in a substance which all the other facts would seem to show to be very uniform in com- position, it is fair to conclude that the explanation of the difference is caused by error. It is certainly a very difficult thing, when dealing with unknown quantities of milk-sugar (lactose), to convert it all into glucose, as must first be done, and then by the Fehling's solution to arrive at an exact knowledge of the amount in the solution examined ; so difficult is it, that many supposed competent chemists have been led into serious error in the attempt, and have published results which will not bear the test of OBSERVATIONS UPON PREVIOUS ANALYSES. 59 searching examination. Therefore, if an exact com- prehension of the composition of human milk is to be attained, the first step must be to throw out all analyses in which the sugar was estimated by the copper test and the casein thence by difference. The copper test seems to give reliable and fairly exact results when known quantities of sugar are dealt with, as is the case in examining cows' milk, for so many analyses have been already made that it is known beforehand very nearly how much sugar will be found. There have been lately published two papers by Dr. Albert R. Leeds,* giving the results of a large number of analyses made by the Gerber Ritthausen's method. The results attained by Dr. Leeds have been fully discussed, and an attempt to show their fallaciousness made, by the author in a paper read before the College of Physicians, which will appear in the Transactions of the College of Physicians of Philadelphia, 3d Series, Vol. VIII. It is not neces- sary to go fully into the subject here, for the process is like many of the older ones, except that sulphate of copper and caustic potash are used to precipitate the casein in the form of an albuminate of copper. Enough has now been said about the previous methods of analysis to show that there is certainly good ground for questioning their accuracy, if it has not been shown that they are all to a greater or less degree inexact ; and the effort has been made * Transactions of the College of Physicians of Philadelphia, 3d Series, Vols, VI and VII, 1883 and 1884- 60 INFANT FEEDING AND MILK ANALYSIS. to prove that the method suggested by the author is exact, or, at any rate, more nearly so than any hith- erto published. Unless, then, it can be shown that the reasoning in the previous chapter does not con- stitute proof, the statements made with regard to the amounts of casein and sugar which exist in human milk have been demonstrated. Nothing, therefore, will be said about the various other methods of analysis, for they are but modifications of those which have already been criticised. CHAPTER V. ARTIFICIAL FEEDING OF INFANTS. In the endeavor to find a food which shall be the best for infants who have to be hand-fed, there are two considerations, either of which might be selected as a basis from which to start. In the first place, the desired goal might be attained by making trial of all sorts of foods, and these being put to the test of experience, the good would be retained and the bad gradually weeded out, until, at last, perhaps the most suitable would be found and slowly in- troduced. On the other hand, the desired end might be attained by trying to produce a food which should be, as nearly as possible, like what nature has provided for the infant. Many trials have been made in the past by both these methods, but to the second one justice has never been done ; for, if the conclusions already detailed are correct, a proper understanding of the composition of hu- man milk, from which to start, has been wanting. A clear understanding being now had of its prox- imate constituents, and the proportions in which they exist, it is possible more intelligently to set about finding how the same elements may be had, and mixed together to make an artificial food like human milk. Cows' milk is almost universally the basis of the foods used, in this country at least. 61 62 INFANT FEEDING AND MILK ANALYSIS. The artificial food which will presently be recom- mended is the outcome of a study of the subject from both of the stand-points suggested, and its advantages are demonstrable. Upon theoretical grounds, it is what a food for infants should be ; for analysis of human milk and cows' milk has shown what their composition is, and in the artifi- cial food the elements have been introduced in the same proportions as they exist in human milk. Experience has for many years past been tending in the direction of proving such a food to be what is needed ; for, while almost innumerable manufac- tured infant foods of every variety have been intro- duced, and have often, for a time, been thought all that could be desired, they have all, one after another, fallen into disuse and been forgotten ; but the use of cows' milk continues to hold its own, and in civilized countries is employed ten times more than all the manufactured foods together. The question however, remains, of how to use it, and the various methods suggested have been almost as numerous as the physicians who have advised them. For a long time the great majority of writers upon infant diseases and diet have recom- mended that cows' milk should be diluted before giving it to young infants ; and this, they agree, is because it contains too much casein, which causes a curd that only infants of the strongest digestion can with safety assimilate. Although it is true that the majority of authori- ties advise that cows' milk should be diluted, still, ARTIFICIAL FEEDING OF INFANTS. 63 there have always been those who used it undiluted. Parrot* says, " in my opinion, it is always best to give the milk pure." Jacobi f disapproves of the use of cream in any form, saying : " It is almost certain that we give too much fat ; it is scarcely ever probable that there is too little. Therefore, the addition of cream is rep- rehensible, no matter in what shape." He states (page no) that human milk contains less fat than cows' milk, but does not say upon what analyses he bases this conclusion. He seems to found his ob- jection to the use of cream upon the fact that Wegscheider found that the " fats are not completely absorbed ; one part leaves the intestine in a saponi- fied condition ; a second part, as free, fatty acid ; a third, as fat in an unchanged condition. " Where no food is given but mother's milk, which contains fat in proportionately smaller quan- tities than cows' milk, and finely suspended and easily absorbed, a good deal of fat is eliminated." It seems scarcely wise, upon such purely theoret- ical grounds, to condemn the use of cream, particu- larly when the experience of many physicians has been that they were able to feed successfully upon cream, or cream mixtures, children they were unable to manage in any other way. Surely, Dr. * Clinique des Nowveau-Nes, V Athrepsie, par J. Parrot. Paris, 1877, page 437. f Hygiene and Public Health, edited by Albert H. Buck. New York, 1879, Vol. !> P- II2 - 64 INFANT FEEDING AND MILK ANALYSIS. Jacobi would not condemn the use of human milk because fat may be found in the stools ! The weight of testimony that cows' milk contains much more casein than human milk, is so great that it is astonishing how almost universally the analyses of human milk of Vernois and Becquerel, and of those who have arrived at like conclusions, have been accepted and given credence, in despite of the fact that the evidence of the senses of every one who has examined into the matter is diametrically opposed to such an acceptance. Although, as already said, the weight of authority has long been in favor of the use of diluted milk, still, there have always been those who recommended it to be used pure. Of later years more and more has been said and written upon the advantages to be derived from the use of cream, or diluted cream. Dr. J. Forsyth Meigs, who was a well-known authority upon the complaints of children, used with great success a mixture of equal parts of milk, cream, lime-water, and a weak arrowroot-water, with a little sugar. Cream mixed with whey, to increase the sugar and lessen the amount of casein, has been recommended. Biedert (Virchow's Archiv, Band 60, 1874) has written an article, and concludes that the best food is cream and water, one part^ to four, with 1 5 grams of milk-sugar to the half litre of the mixture, the strength of this to be gradually increased. Biedert made many experiments comparing the relative coagulability of human and cows' milk, and again the digestibility of the coagulum ; as can therefore ARTIFICIAL FEEDING OF INFANTS. 65 be presupposed, his experiments turned mainly upon the two kinds of casein and their differences. He concludes that " there are two important points in which human and cows' milk are unlike : first, in the different amounts of casein contained ; and second, in the absolute chemical difference of the two sorts of casein. The first of these consider- ations would be of little importance, however, if the analyses which place the average of casein in human milk at 4 per cent, are correct ; its importance, on the other hand, would be very great if it usually contains — as I, in. agreement with Vierordt's view, believe — only from 2 to 2^ per cent. I think many further analyses are necessary to establish absolutely this point. Even if this view is accepted, however, dilution of cows' milk with equal or more parts of water is not sufficient to remove the differences. It is well known that such a dilution does not remove all the disadvantages which arise in the use of cows' milk, and my clinical experience has taught me that even dilution with two parts of water does not attain the desired end ; and the explanation of this positive irremovable difference is to be found in the impor- tant chemical differences which exist, the casein of cows' milk coagulating so much more easily, and the coagulum being so much more firm than is the case with the casein of human milk ; and, on the other hand, the coagulum being so much more difficult of solution or digestion. " Until we succeed in actually making the casein of cows' milk identical with that of human milk, it 66 INFANT FEEDING AND MILK ANALYSIS. will be necessary to give infants only so much of it as they can digest (no matter how great the neces- sary dilution may be), and to make up to them with carbo-hydrates (fat and milk-sugar) the lack of albuminates in the food." He further says : " After numerous experiments, I have come to the conclu- sion that the amount of cow casein which an infant's food should contain is i per cent. The fat and sugar in cows' milk appear to be as easily digested, and in no wise different from those contained in human milk. If, therefore, one-eighth of a litre of sweet cream (which, according to Hoppe, contains 9^ per cent, of fat, 3 per cent, of sugar, and 4 per cent, of casein) is diluted with three-eighths of a litre of water, which has been previously boiled, and milk- sugar is added in the proportion of 1 5 grams to the half litre, the desired cream mixture is produced, and contains 1 per cent, of casein, 2.4 per cent, of fat, and 3.6 per cent, of milk-sugar, which will be found, under all circumstances, to be well borne, and is a sufficiently nourishing food." The greatest part of Biedert's admirable article consists of a detail of experiments made of treating cows' and human milk, and the caseins obtained from both sorts, with a variety of reagents, and observing the different relative effects produced. His conclusion is that " the pure casein of human milk is, in both its physical and chemical nature, different from that of cows' milk." The casein of cows' milk, when iso- lated, has always an acid reaction, while, on the contrary, that obtained from human milk is always ARTIFICIAL FEEDING OF INFANTS. 67 alkaline. If human casein is treated in a certain way with acid, there is produced an " acid modifica- tion of human casein," which has many points of resemblance with ordinary cow casein ; on the other hand, by treating cow casein with alkali, a substance is produced which shows, with many reagents, iden- tically the same changes that are, by like treatment, produced in human milk. After careful examina- tion of these two substances, however, Biedert con- cludes that " cow casein treated with alkali is, in many respects, much more like human casein than the original cow casein ; yet it always shows unmis- takable differences." Although he makes a strong case, and there are many reasons in favor of accept- ing his conclusions, yet, in the present state of knowledge of casein, the difference cannot be con- sidered as absolutely demonstrated. There are objections to such a belief: it has been already shown that human milk contains only one- third the amount of casein that exists in cows' milk ; and there is a further important difference, which Biedert also appreciates, that human milk is always alkaline, while, on the contrary, cows' milk is acid. A coagulum, therefore, produced in a solution which is relatively so concentrated as is the case in cows' milk, and further, in a fluid which is acid in reaction, is a very much denser and larger one than can be had from the relatively weak solution in human milk ; and it is quite possible, therefore, that the difference may be owing to the different degrees of concentration, and the difference of the fluid media 68 INFANT -FEEDING AND MILK ANALYSIS. in which the casein is held ; it cannot, therefore, yet be conceded that Biedert has absolutely demon- strated that the two caseins are chemically and physically different, although he has brought many strong arguments to bear. It is impossible to decide with certainty about casein in all its relations, while as yet it is not even known whether it is a simple or compound substance. Its solubility or insolubility after it has once been precipitated, depends, in great part, upon how the original coagulation was effected, and whether or not it was thoroughly dried. If casein is once thoroughly dried for a good many hours at ioo° C, it becomes absolutely insoluble in water, and will not dissolve even in a strong solution of caustic soda. Lehman {Physiological Chemistry, Cavendish Society Translation, Vol. I, p. 378) says : " I believe that the jelly-like coagula of women's milk are more dependent on the alkaline state of the fluid than on any peculiarity in the casein ; at all events, I have found that women's milk, when acid, yields a much thicker coagulum than when alkaline, and cows' milk, when alkaline, a much looser coagulum than when acid — facts of the highest interest and value in relation to dietetics." Whatever may finally be decided about casein — whether those of cows' and human milk are as different as Biedert believes he has proved, or whether they are nearly alike, the difference being merely that the quantities are not the same and the containing fluid media different — what most con- ARTIFICIAL FEEDING OF INFANTS. 69 cerns the subject in hand is the relatively small quantity that exists in human milk; for it shows conclusively that in a food for infants, the amount of casein in cows' milk must, by some means, be reduced to equal the amount in human milk. The correct conclusion of Biedert, that not more than one per cent, of cow casein should be present in a food for infants, is the more surprising as he arrives at the opinion from a totally different reason from the true one, that human milk contains only one per cent. Although Biedert's conclusions are very instruc- tive, as he arrives at them from clinical experience, and surprisingly correct in many respects, he goes astray in assuming an incorrect standard of the aver- age composition of cream. The estimate of Hoppe, which he assumes to be correct, places the amount of casein too high; for, as may be seen by a refer- ence to Tables IV and VI, cows' milk and cream do not contain more casein than sugar. The usual estimates rate the casein too high, at the expense of the sugar. This being the case, and Biedert reck- oning the composition of his cream mixture from an incorrect standard, and not from any analysis, either of the cream or the mixture itself, as should have been done, places his fat amount too low, as only a very poor cream is as weak in fat as his standard rates it. A mixture made as he directs, is far weaker in sugar than human milk, and there- fore, although perhaps proper for temporary use in cases of indigestion, cannot be accepted as a stand- ard of what an infant food should be ; and it entirely JO INFANT FEEDING AND MILK ANALYSIS. fails to accomplish what he says should be done — make up to the infant by an excess of carbo-hydrates the lack of albuminates which exists in the food — for it only contains about half as much sugar as exists in human milk. In a later work than that which has already been so extensively quoted by Biedert,* he states that the differences between the coagula produced by rennet in cows' and woman's milk are as follows : " first, the different percentages of casein ; second, the different menstrua, especially in regard to the amount of free alkali ; third, in the absolute chemical differ- ences between the two sorts of casein." He finds fault with the statement that human milk contains only abput one per cent, of casein, and the sugges- tion that in this, the great difference in the amounts of casein, lies the most important differ- ence between human and cows' milk, and not in any chemical difference between the two kinds of casein, which is not even as yet positively proved, although Dr. Biedert thinks it has been. Biedert is in error when he says the Nessler's reagent will not act upon unaltered casein, but will act only after it has been converted into ammonia. He reiter- ates his former statement that the best food for new- born infants is his cream mixture with milk-sugar (cream, 125 grams; water, which has been boiled, 375, and milk-sugar, 15). * Untersuchungen uber die Ckemischen Unterschiede der Men- schen und Kuhmilch, von Dr. Ph. Biedert, Stuttgart, 1884. pages 2, 48, 60, and 61. ARTIFICIAL FEEDING OF INFANTS. 7 1 All these facts show that the tendency has been constantly toward the truth, and that physicians have been learning empirically for what reasons cows' milk has failed as an infant food, and how the diffi- culties which its use entailed were to be overcome. The use of cream has been advised ; cream and whey ; diluted milk ; diluted milk with milk-sugar ; cream, milk, lime-water, and arrowroot-water ; and finally comes Biedert's cream mixture, and he arrives more nearly at the true solution of the difficulty than any of the others, but still falls wide of the mark, from want of a precise knowledge of the composi- tion of human milk, and of cows' milk and cream. Investigators have thus, year by year and step by step, been approaching the desired goal, and it needed but a touch for light to be let in upon the whole subject. Many hours and much careful and patient labor have been expended upon investiga- tions in this field, and no single worker could have done his part without having before him the results of the labors of his predecessors to guide him a long way in the field, and give him easily the knowledge which would enable him, after much toil and trou- ble, to advance one little step more toward what was previously unknown. Thus, no individual in- vestigator, no matter how important the advance in knowledge he may have made, should assume too large a share of credit ; for it can be but a very small part of the great whole, and would be value- less but for the rest, into which it fits, and completes that which would otherwise be useless. 72 INFANT FEEDING AND MILK ANALYSIS. The necessary data being now at hand, it is com- paratively easy to construct a food which shall at least be more nearly what is needed than any pre- vious one. In making such a food there are two matters to be considered : the proximate constituents must be in the same relative proportions as they are found in human milk, and they must be in a medium which shall be, as human milk is, alkaline. This latter end is easily accomplished by the use of a due amount of lime-water, and is justified by the fact that it is a matter of experience, and almost universally acknowledged as true, that it is a most useful adjunct, rendering cows' milk more easy of digestion by the human stomach. The quantity of lime-water to be used should be one-fourth of the total by measure. This may seem to many per- sons an excessive quantity, but when it is under- stood that if made as ordinarily directed, by agitating water with lime and then filtering, it contains only a very minute amount of lime, it becomes plain that the use of lime-water means the administration of a great deal of water and very little solid matter. That the use of lime-water (alkali) in an infant food makes a difference in its behavior with some reagents is shown by the following experiments. A food was made in the proportions which will presently be given, and 10 c.c. of it agitated with ether and alcohol, as directed in Chapter I, for the extraction of the fat ; it was found that the coagu- lation took place in the form of a fine net-work, which remained permanently distributed through ARTIFICIAL FEEDING OF INFANTS. 73 the lower stratum of the liquid, no sediment form- ing at the bottom. When an exactly similar mix- ture was made, except that the lime-water was re- placed with water, leaving the fluid acid, and this agitated with ether and alcohol, thick, heavy curds formed, which at once sank to the bottom. Again, when two mixtures — one with and the other with- out lime-water — were treated with ten drops of acetic acid, the one without lime-water showed much larger, heavier coagula than that which con- tained lime-water. These experiments show with certainty that the addition of lime-water does alter the coagulability of the casein when experimented with, whatever may take place in the stomach ; and Lehmann's opinion has been already quoted, that the acidity or alkalinity of milk makes a difference in the formation of the coagulum. Whatever may be the value of these artificial experiments, the great reason for the use of lime-water is that the expe- rience of man has found it good, and that is suffi- cient reason for its use in the present state of knowl- edge. It is quite possible that in the future some- thing better may be found, phosphate of lime, per- haps, for it is the salt which exists in milk in larger quantity ■ than any other; but further and exhaustive study of the inorganic constituents of both human and cows' milk will be required to place this matter upon an exact scientific basis. It is very desirable that further study of the salts of milk should be prosecuted, and it is much to be hoped that in the near future exhaustive analyses 6 74 INFANT FEEDING AND MILK ANALYSIS. will be made. The amount of inorganic matter in cows' milk is so much greater than that in human milk that, as there is at present no means of remov- ing it without altering or destroying the other com- ponent parts, no infant food can be made exactly like human milk in respect to the amount of salts contained. So far as bringing the other proximate constitu- ents to like proportions with those in human milk, the first step must be to so dilute with water as to get the desired quantity of casein ; the fat and sugar can be increased by the use of the necessary quanti- ties of cream and commercial milk-sugar. Taking the averages of cream and good city milk as already given (see table), it will be found by calculation that if there be mixed together 10 c.c. of cream, 5 c.c. of milk, 10 c.c. of lime-water, and 15 c.c. of water, with 2.2 grams of milk-sugar, the desired mixture is had. That this is the case was not trusted to mere calculation, but an analysis of the mixture was made, both to verify the calculation and to observe how the mixture behaved when subjected to the analytic processes, whether it in its reactions more closely resembled cows' milk, with which it was made, or human milk. Table VIII shows the results obtained by such analyses. The easiest way to prepare and use the food is as follows : There must be obtained from a reliable druggist packages of pure milk-sugar containing seventeen and three-quarters (17^) drachms each. The contents of one package is to be dissolved in a ARTIFICIAL FEEDING OF INFANTS. 75 pint of water, and it is best to have a bottle which will contain just one pint, as there is then no need for further measuring. The contents of one of the sugar packages is put into the bottle, and when filled with water the sugar soon dissolves, and it is ready for use. The dry sugar keeps indefinitely, but after it is once dissolved it sours if kept more than a day or two in warm weather ; it is understood, therefore, that the sugar-water must be kept in a cool place, and if it should at any time become sour, which is easily discovered if it is smelled and tasted, it should be thrown out, and after the bottle has been carefully washed with boiling water, the contents of a fresh package dissolved. A milkman must be found who will serve good milk and cream, fresh every day. By good milk is meant ordinary milk, such as is easily procured in most cities, and not rich Jersey milk ; and in the same way the cream should be such as is ordinarily used in tea and coffee, and not the very rich cream of fancy cattle. The reason that ordinary milk and cream are recom- mended is because they are within the reach of almost every one, and not because they are any better than the rich milk of high-bred stock. If Jersey milk was to be used, it would be necessary to analyze specimens, and then make the necessary calculations as to how to dilute it to obtain the desired relative proportions of the proximate prin- ciples. When the child is to be fed, the nurse should mix together two (2) tablespoonfuls of cream, one (1) of milk, two (2) of lime-water, and three (3) 76 INFANT FEEDING AND MILK ANALYSIS. of the sugar-water, and then, as soon as the mixture has been warmed, it may be poured into the bottle, and the food is ready for use. If the infant is healthy, this quantity will not satisfy it after the first few weeks, and then double the quantity must be prepared for each feeding. Twice as many table- spoonfuls of each of the ingredients must be mixed together, making sixteen tablespopnfuls (about half a pint) in all. This food should not be given any stronger until the child is eight or nine months old, at least ; but if the infant is a healthy one, it may take as much of it as it wants, but always of the same strength. A robust infant will often take three pints, or even more, in each twenty-four hours. It is an easy matter for any one to learn how to make lime- water ; and it is advisable to have it made at home, for a great deal is used, and if it is made at home much trouble and expense are saved. Table VIII shows the proportions in which the various proximate constituents exist in different kinds of milk, and of cream, and of foods. With regard to the amount of food taken by a healthy infant there has been much disagreement, and the same is the case with the question of the propriety of increasing, from week to week, the strength of any artificial food given to infants. Most authorities have advised that the artificial foods should be increased in concentration until finally, if cows' milk was used, it should be given pure. The propriety of this procedure during the earlier ARTIFICIAL FEEDING OF INFANTS. 77 O t^ N O O *n \0 t>. « cq « ii-ioo O **} ►* t-^oo t-« \d o\ to ^ '** O00 CiO m^^O O r-- wi ^- « C\ *-* ro « t-*\c to •■tf-Qo VO N idO\mCO w i-h ih « ro ^h m\o t^oo 0\ o N MTf u-ivO *-» g| si «fe :; „g3°S 'g-S-M' ' 5 ^ ■■as = s=s h OVO00 »n O *-» ^ O t-^ CT\ tJ-00 fO **■ r*. CT\vO O "") io q oo n n « in tN «-H O (^ PO 1O00 fO i>. d cf» d -! W M IT) •■fed 0-gEB"* as 2 --I sights < (J O — *S U in O m N os w O r- O W tN O ""» P- o cs Q « t^-vo ■* CT\ ■* >°P S 9 o « a" e J £•§ la S g = §g»*g!jS vOOO ^-O O ii N O ■<*• ■■* [> rt 3 S « s a s 4J V fi fl O o *c a is 0) o T) a o CJ a > (A StT 1. CO ^ | n * v w ^ a . a. m js -a € s "55 > e o c c a .- in O ^ C 43 38 QUANTITIES of cows' milk to be given 80 Quantity of food to be taken 76 RAPIDITY of method of determining fat, etc 22 Reaction of human milk 33 Results of analysis, calculation of 17, 2 4 Rich milk, not always yellow 20 SEMICHON, Ernest 9 Simon 26 Simon's method s 1 Solubility of casein 68 Statement of error in analysis 18, 23 24 Strippings 29 Sugar, amount in human milk large 4 2 of milk, insoluble in alcohol 55 separation of * 7 TABLE 1 3* II 32 III - 34 IV 36 V 36 VI 37 VII 40 VIII -. 77 Time required to estimate fat, water, and total solids 22 required to make analysis 22, 30 102 INDEX. u V PAGE NIFORMITY of composition of cows* milk 42 ERNOIS and Becquerel 26, 39 Vernois and Becquerel's method 49 WANKLYN 24 and Chapman, water analysis 45 Wanklyn's method 54 Wanklyn, uniformity of composition of cows' milk 42 Water analysis, Wanklyn and Chapman 45 Water-bath, description of. 15 use of. 19 CATALOGUE No. 7, MAY, 1886. A CATALOGUE OF BOOKS FOR STUDENTS; INCLUDING A FULL LIST OF The ? Quiz-Comfiends? , MANUALS, Text-Books and Students' Aids, PUBLISHED BY P. BLAKISTON, SON & CO. Medical Booksellers, Importers and Publishers. LARGE STOCK OF ALL STUDENTS' BOOKS, AT THE LOWEST PRICES. No. 1012 WALNUT STREET, PHILADELPHIA. *»*For sale by all Booksellers, or any book will be sent by mail, postpaid, upon receipt of price. Catalogues of books on all branches of Medicine, Dentistry, Pharmacy, etc., supplied upon application. ? QUIZ-COMPENDS? A NEW SERIES OF COMPENDS FOR STUDENTS. For Use in the Quiz Class and when Preparing for Examinations. Price of Each, Bound in Cloth, $1.00 Interleaved, $1.25. Based on the most popular text-books, and on the lec- tures of prominent professors, they form a most complete set of manuals, containing information nowhere else collected in such a condensed, practical shape. The authors have had large experience as quiz-masters and attaches of colleges, with exceptional opportunities for noting the most recent advances and methods. The arrangement of the subjects, illustrations, types, etc., are all of the most improved form, and the size of the books is such that they may be easily carried in the pocket. They are constantly revised, so as to include the latest and best teachings, and can be used by students of any college. No. 1. ANATOMY. (Illustrated.) THIRD REVISED EDITION. I A Compend of Human Anatomy. By Samuel O. L. Potter, m.a., m.d., U. S. Army. With 63 Illustrations. " The work is reliable and complete, and just what the student needs in reviewing the subject for his examinations. " — The Physi- cian and Surgeon's Investigator, Buffalo, N. Y. " The arrangement is well calculated to facilitate accurate memo- rizing, and the illustrations are clear and good." — North Carolina Medical Journal. Nos. 2 and 3. PRACTICE. NEW REVISED EDITIONS. A Compend of the Practice of Medicine, especially adapted to the use of Students. By Dan'l E. Hughes, M.D., Demonstrator of Clinical Medicine in Jefferson Medical College, Philadelphia. Second Edition. En- larged and thoroughly Revised. In two parts. Part I. — Continued, Eruptive, and Periodical Fevers, Diseases of the Mouth, Stomach, Intestines, Peritoneum, Biliary Passages, Liver, Kidneys, Intestinal Parasites, etc., and General Diseases. Part II. — Diseases of the Respiratory System, Circu- latory System and Blood, Nervous System, etc. Price of each Book, Cloth, $1.00. Interleaved for Notes, $1.25. THE ? QUIZ-COMPENDS ?. *#* These little books can be regarded as a full set of notes upon the Practice of Medicine, containing the Synonyms, Definitions, Causes, Symptoms, Prognosis, Diagnosis, Treatment, etc., of each disease, and includ- ing a number of new prescriptions. They have been compiled from the lectures of prominent Professors, and reference has been made to the latest writings of Pro- fessors Flint, Da Costa, Bartholow, Roberts, etc. " It is brief and concise, and at the same time possesses an accu- racy not generally found in compends." — Jas. M. French, M.D., Ass't to ike Prof, of Practice, Medical College of Ohio, Cincinnati. ** The book seems very concise, yet very comprehensive. . . . An unusually superior book." — Dr. K. T. Bruen, Demonstrator of Clinical Medicine, University of Pennsylvania. " I have used it considerably in connection with my branches in the Quiz-class of the University of La." — % H. Bemiss. " Dr. Hughes has prepared a very useful little book, and I shall take pleasure in advising my class to use it." — Dr. George W Hall, Prof, of Practice, St. Louis College of Phys. and Surgeons' No. 4. PHYSIOLOO-Y. Illustrated. THIRD REVISED EDITION. A Compend of Human Physiology, adapted to the use of Students. By Albert P. Brubaker, m.d., De- monstrator of Physiology in Jefferson Medical College, Philadelphia. Third Ed. Enlarged and Revised. '* Dr. Brubaker deserves the hearty thanks of medical students for his Compend of Physiology. He has arranged the fundamental and practical principles of the science in a peculiarly inviting and accessible manner. I have already introduced the work to my class." — Maurice N. Miller, M.D., Instructor in Histology, for- merly Demonstrator of Physiology, University City of New York. " * Quiz-Compend ' No. 4 is fully up to the high standard estab- lished Dy its predecessors of the same series." — Medical Bulletin, Philadelphia. " I can recommend it as a valuable aid to the student." — C. N. Ellin-wood, M.D., Professor of Physiology, Cooper Medical Col- lege, San Francisco. " This is a well written litde book." — London Lancet. No. 5. OBSTETRICS. Second Ed. A Compend of Obstetrics. For Physicians and Students. By Henry G. Landis, m.d., Professor of Obstetrics and Diseases of Women, in Starling Medical College, Columbus. New Revised Ed. New Illustrations. " We have no doubt that many students will find in it a most valuable aid in preparing for examination." — The American jfour- nal of Obstetrics. " It is complete, accurate and scientific. The very best book of its kind I have seen." — J. S. Knox, M.V., Lecturer on Obstetrics, Rush Medical College, Chicago. Price of each Book, Cloth, $1.00. Interleaved for Notes $1.26. THE ? QUIZ-COMPENDS ?. " I have been teaching in this department for many years, and am free to say that this will be the best assistant I ever had. It is ac- curate and comprehensive, but brief and pointed." — Prof. P. D. Yost, St. Louis. No. 6. MATERIA MEDIOA. Revised Ed. A Compend on Materia Medica and Therapeutics, with especial reference to the Physiological Actions of Drugs. For the use of Medical, Dental, and Pharma- ceutical Students and Practitioners. Based on the New Revision (Sixth) of the U. S. Pharmacopoeia, and in- cluding many unofficinal remedies. By Samuel O. L. Potter, m.a., m.d., U. S. Army. " I have examined the little volume carefully, and find it just such a book as I require in my private Quiz, and shall certainly re- commend it to my classes. Your Compends are all popular here in Washington." — John E. Brackett, M.D., Professor of Materia Medica and Therapeutics, Howard Medical College, Washington. " Part of a series of small but valuable text-books. . . . while the work is, owing to its therapeutic contents, more useful to the medical student, the pharmaceutical student may derive much use- ful information from it."— N. Y. Pharmaceutical Record. No. 7. CHEMISTRY. Revised Ed. A Compend of Chemistry. By G. Mason Ward, m.d., Demonstrator of Chemistry in Jefferson Medical Col- lege, Philadelphia. Including Table of Elements and various Analytical Tables. " Brief, but excellent. ... It will doubtless prove an admirable aid to the student, by fixing these facts in his memory. It is worthy the study of both medical and pharmaceutical students in this branch." — Pharmaceutical Record, New York. No. 8. VISCERAL ANATOMY. SECOND EDITION. ILLUSTRATED. A Compend of Visceral Anatomy. By Samuel O. L. Potter, m.A., m.d., U. S. Army. With 40 Illustrations. *#* This is the only Compend that contains full descriptions of the viscera, and will, together with No. i of this series, form the only complete Compend of Anatomy published. " This work is very happily arranged, very thorough in practical details, and will no doubt prove universally popular with medical students." — Medical Herald. " I believe it will prove of great usefulness to the busy teacher or student; short, concise helps are always welcome." — Dr. P. N. Hall, Demonstrator of Anatomy, College of Physicians and Sur- geons, Chicago. " It is a very concise and convenient help to the memory, and quite accurate. ' — Prof. L. B. How, Medical Department, Dart- mouth College. Price of Each Book, Cloth, $1.00. Interleaved for Notes, $1.26. THE ? QUIZ-COMPENDS ?. No. 9. SURGERY. Second Edition. ILLUSTRATED. A Compend of Surgery; including Fractures, Wounds, Dislocations, Sprains, Amputations and other opera- tions, Inflammation, Suppuration, Ulcers, Syphilis, Tumors, Shock, etc. Diseases of the Spine, Ear, Eye, Bladder, Testicles, Anus, and other Surgical Diseases. By Orville Horwitz, a.m., m.d., with 62 Illustra- tions. Second Edition. Enlarged and Revised. *** This compend has been prepared with great care, from the standard authorities on Surgery and from notes taken by the author during attendance on lectures by prominent professors. The rapid sale of the first edition allowed the addition of much valuable matter, besides a thorough revision of the whole book. No. 10. ORGANIC CHEMISTRY. A Compend of Organic Chemistry, including Medical Chemistry, Urine Analysis, and the Analysis of Water and Food, etc. By Henry Leffmann, m.d., Pro- fessor of Clinical Chemistry and Hygiene in the Phila- delphia Polyclinic ; Professor of Chemistry, Penn- sylvania College of Dental Surgery ; Member of the N. Y. Medico-Legal Society. Cloth. $1.00. Interleaved, for the addition of Notes, $1.25. " Compact, substantial and exact; well suited as a remembrancer to students." — Pacific Medical and Surgical Journal. " This neat, handy and exceedingly useful volume is a valuable aid to the student." — Pharmaceutical Record. " It contains, in compact form, the most of modern organic and medical chemistry essential to the student of medicine, and will be of great value in bringing this subject within his grasp." — C. C. Howard, Prof, of Chemistry, Starling Medical College, Colum- bus, Ohio. " It has the decided merit of being written in a clear and under- standable language." — Dr. J. Sickels, Instructor in Chemistry, University Medical College, New York. No. 11. PHARMACY. A Compend of Pharmacy. Based upon " Remington's Text-Book of Pharmacy." By F. E. Stewart, m.d., ph. G., Quiz Master in Chemistry and Theoretical Pharmacy, Philadelphia College of Pharmacy; De- monstrator and Lecturer in Pharmacology, Medico- Chirurgical College ; Member of the American Phar- maceutical Association, etc. J&&- The ? Quiz Compends ? are adapted to students of any college, because they are based upon the text-books in use through- out the country. They contain the latest and best information, in such a shape that it can be easily memorized. Price of Each Book, Cloth, $1.00 ; Interleaved for Notes $1.25. 6 STUDENTS' TEXT-BOOKS AND MANUALS. ANATOMY. Holden's Anatomy. A manual of Dissection of the Human Body. Fifth Edition. Enlarged, with Marginal References and over 200 Illustrations. Octavo. Cloth, 5.00; Leather, 6.00 Bound in Oilcloth, for the Dissecting Room, $4.50. " No student of Anatomy can take up this book without being pleased and instructed. Its Diagrams are original, striking and suggestive, giving more at a glance than pages of text description. * * * The text matches the illustrations in directness of prac- tical application and clearness of detail.'* — New York Medical Record. Holden's Human Osteology. Comprising a Description of the Bones, with Colored Delineations of the Attachments of the Muscles. The General and Microscopical Structure of Bone and its Development. With Lithographic Plates and Numerous Illus- trations. Sixth Edition. 8vo. Cloth, 6.00 Heath's Practical Anatomy. Sixth London Edition. 24 Col- ored Plates, and nearly 300 other Illustrations. Cloth, 5.00 CHEMISTRY. Bartley's Medical Chemistry. A text-book prepared specially for Medical, Pharmaceutical and Dental Students. With 40 Illustrations, Plate of Absorption Spectra and Glossary of Chemi- cal Terms. Cloth, 2.50 *#* This book has been written especially for students and phy- sicians. It is practical and concise, dealing only with those parts of chemistry pertaining to medicine ; no time being wasted in long descriptions of substances and theories of interest only to the advanced chemical student. Bloxam's Chemistry, Inorganic and Organic, with Experiments. Fifth Edition, nearly 300 Illustrations. Cloth, 3.75 ; Leather, 4.75 Muter's Practical and Analytical Chemistry. 8vo. Cloth, 2.50 Richter's Inorganic Chemistry. A text-book for Students. Second American, from Fourth German Edition. Translated by Prof. Edgar F. Smith, ph.d. 89 Wood Engravings and Colored Plate of Spectra. Just Ready. Cloth, 2.00 Richter's Organic Chemistry, or Chemistry of the Carbon Compounds. Translated by Prof. Edgar F. Smith, ph.d. Illustrated. Just Ready. Cloth, 3.00 Trimble. Practical and Analytical Chemistry. A Course in Chemical Analysis, by Henry Trimble, Prof, of Analytical Chem- istry in the Phila. College of Pharmacy. Illus. 8vo. Cloth, 1.50 Wolff's Applied Medical Chemistry. By Lawrence Wolff, m.d., Demonstrator of Chemistry in Jefferson Medical College, Philadelphia. Just Ready. Cloth, 1.50 JW See pages 2 to j for list of ? Quiz-Compends ? STUDENTS' TEXT-BOOKS AND MANUALS. 7 CHILDREN. Goodhart and Starr. The Diseases of Children. A Manual for Students and Physicians. By J. F. Goodhart, m.d., Physi- cian to the Evelina Hospital for Children ; Assistant Physician to Guy's Hospital, London. American Edition, Revised and Edited by Louis Starr, m.d., Clinical Professor of Diseases of Children in the Hospital of the University of Pennsylvania; Physician to the Children's Hospital, Philadelphia. Containing many new Prescriptions, a List of over 50 Formulae, conforming to the U. S. Pharmacopoeia, and Directions for making Artificial Human Milk, for the Artificial Digestion of Milk, etc. Just Ready. Demi-Octavo, 738 Pages. Cloth, 3.00; Leather, 4.00 The New York Medical Record says : — " As it is said of some men, so it might be said of some books, that they are 'born to greatness.* This new volume has, we believe, a mission, particu- larly in the hands of the younger members of the profession. In these days oi prolixity in medical literature, it is refreshing to meet with an author who knows both what to say, and when he has said it. The work of Dr. GoodharC (admirably conformed, by Dr. Starr, to meet American requirements) is the nearest approach to clinical teaching, without the actual presence of clinical material, that we have yet seen. The details of management so gratefully read by the young practiticner are fully elucidated. Altogether, the book is one of as great practical working value as we have seen for many months." Day. On Children. A Practical and Systematic Treatise. Second Edition. 8vo. 752 pages. Cloth, 3.00; Leather, 4.00 Meigs and Pepper. The Diseases of Children. Seventh Edition. 8vo. Cloth, 6.00; Leather, 7.00 Starr. Diseases of the Digestive Organs in Infancy and Childhood. By Louis Starr, m.d., Prof, of Diseases of Children, Hospital of the University of Pennsylvania. Illus. Cloth, 2.50 DENTISTRY. Flagg's Plastics and Plastic Filling. 2d Ed. Cloth, 4.00 Gorgas. Dental Medicine. A Manual of Materia Medica and Therapeutics, by Professor F. J. S. Gorgas, m.d., d.d.s., Pro- fessor of the Principles and Practice of Dental Science, in Den- tal Department, University of Maryland. 8vo. Second Edition. Revised and Enlarged. Cloth, 3.25 Harris' Principles and Practice of Dentistry. Including Anatomy, Physiology, Pathology, Therapeutics, Dental Surgery and Mechanism. Eleventh Edition. Revised and enlarged by Professor Gorgas. 744 Illustrations. Cloth, 6.50 ; Leather, 7.50 Richardson's Mechanical Dentistry. Third Edition. 185 Illustrations. 8vo. Cloth, 4.00; Leather, 4 75 Stocken's Dental Materia Medica. Third Edition. Cloth, 2.50 .63=- See pages 2 to 5 for list 0/ ? Quiz- Commends ? 8 STUDENTS' TEXT-BOOKS AND MANUALS. Dentistry : — Continued. Tomes' Dental Anatomy, Human and Comparative. Sec- ond Edition, jgi Illustrations. Cloth, 4.25 Tomes' Dental Surgery. New Revised Edition. Preparing. Taft's Operative Dentistry. A Text-book for Dental Students and Practitioners. Fourth Edition. Over 100 Illustrations. Cloth, 4.25 ; Leather, 5,00 \ DICTIONARIES. Cleaveland's Pocket Medical Lexicon. Thirty-first Edition. Giving correct Pronunciation and Definition of. Terms used in Medicine and the Collateral Sciences. Very small pocket size, red edges. Cloth, .75 ; pocket-book style, 1.00 Longlcy's Pocket Dictionary. The Student's Medical Lexicon, giving Definition and Pronunciation of all Terms used in Medi- cine, with an Appendix giving Poisons and Their Antidotes, Abbreviations used in Prescriptions, Metric Scale of Doses, etc. 24mo. Cloth, 1. 00; pocket-book style, 1.25 Harris' Dictionary of Medical Terminology and Dental Surgery By Prof, Gorgas. Fourth Edition. Cloth, 6.50 ; Leather, 7.50 EYE. Arlt, Diseases of the Eye. Including those of the Conjunc- tiva, Cornea, Sclerotic, Iris and Ciliary Body. By Professor Fred. Ritter von Arlt. Translated by Dr. Lyman Ware. Illus- trated. 8vo. Cloth, z.50 Higgins. Ophthalmic Practice. A Handbook for Students and Practitioners. i6mo. Cloth, .50 Macnamara. On Diseases of the Eye. Fourth Edition, revised, with Marginal References, numerous Colored Plates and Diagrams, Wood Cuts and Test Types. Cloth, 4.00 HYGIENE. Parke's Practical Hygiene. Sixth Edition, enlarged. Illus- trated. 8vo. Cloth, 3.00 Wilson's Handbook of Hygiene and Sanitary Science. Fifth Edition. Revised and Illustrated. Cloth, 2.75 MATERIA MEDICA AND THERAPEUTICS. Biddle's Materia Medica. Tenth Edition. For the use of Students and Physicians. By the late Prof. John B. Biddle, m.d., Professor of Materia Medica in Jefferson Medical College, Phila- delphia. The Tenth Edition, thoroughly revised, and in many parts rewritten, by his son, Clement Biddle, m.d., Past Assistant Surgeon, U. S. Navy, assisted by Henry Morris, m.d., Demon- strator of Obstetrics in Jefferson Medical College. 8vo., illus- trated. Just Ready. Cloth, 4.00 ; Leather, 4.75 fl®~ Seepages 2 to 5 for list of FQuiss-Compendsf STUDENTS' TEXT-BOOKS AND MANUALS. 9 Biddle's Materia Medico, and Therapeutics ; — Continued. " The larger works usually recommended as text-books in our medical schools are too voluminous for convenient use. This work will be found to contain in a condensed form all that is most valuable, and will supply students with a reliable guide." — Chicago Med. Jl, MerreU's Digest of Materia Medica. 8vo. Half Calf, 4.00 Roberts' Compend of Materia Medica and Pharmacy. By the author of " Roberts' Practice." Cloth, 2.00 "It contains an immense amount of matter." — The National Druggist. Headland's Action of Medicines. 9th Ed. 8vo. Cloth, 3.00 Waring. Therapeutics. A Practical Manual. Fourth Edition, revised and enlarged. In Press. MEDICAL JURISPRUDENCE. Reese. A Text-book of Medical Jurisprudence and Toxi- cology. By John J. Reese, m.d., Professor of Medical Juris- prudence and Toxicology in the Medical and Law Departments of the University of Pennsylvania ; Vice-President of the Med- ical Jurisprudence Society of Philadelphia ; Physician to St. Joseph's Hospital ; Corresponding Member of The New York Medico-legal Society. Demi-Octavo. Cloth, 4.00; Leather, 5.00 " Professor Reese is so well known as a skilled medical jurist, that his authorship of any work virtually guarantees the thorough- ness and practical character of the latter. And such is the case in the book before us. * * * * We might call these the essentials for the study of medical jurisprudence. The subject is skeletonized, condensed, and made thoroughly up to the wants of the general medical practitioner, and the requirements of prosecuting and de- fending attorneys. If any section deserves more distinction than any other, as to intrinsic excellence, it is that on toxicology. This part of the book comprises the best outline of the subject in a given space that can be found anywhere. As a whole, the wDrk is everything it promises, and more, and considering its size, con- densation, and practical character, it is by far the most useful one for ready reference, that we have met with. It is well printed and neatly bound." — New York Medical Record. Abercrombie's Students' Guide to Medical Jurisprudence. 12010. Cloth, 2.50 Mann's Manual of Psychological Medicine, and Allied Ner- vous Diseases. Their Diagnosis, Pathology and Treatment, and their Medico-Legal Aspects. Illustrated. 8vo. Cloth, 5.00; Leather, 6.00 Woodman and Tidy's Medical Jurisprudence and Toxi- cology. Chromo-Lithographic Plates and 116 Wood engravings. Cloth, 7.50 ; Leather, 8.50 J8&~ See pages 2 to 5 for list of ? Quiz-Compends? 10 STUDENTS' TEXT-BOOKS AND MANUALS. MISCELLANEOUS. Beale. Slight Ailments. Their Nature and Treatment. Illus- trated. 8vo. Paper cover, .75; Cloth, 1.25 Dulles. Surgical and other Emergencies. Illustrated. Sec- ond Edition. 121110. Cloth, .75 Fothergill. Diseases of the Heart and Their Treatment. Second Edition. 8vo. Cloth, 3.50 Tanner. Memoranda of Poisons. Their Antidotes and Tests. Fifth Edition, wmo. Cloth, .75 Allingham . Diseases of the Rectum . Fourth Edition. Illus- trated. 8vo. Paper covers, .75; Cloth, 1.25 OBSTETRICS AND GYNAECOLOGY. Byford. The Diseases of Women. By W. H. Byford, a.m., m.d., Professor of Gynaecology in Rush Medical College; of Obstetrics in the Woman's Medical College ; and Surgeon to the Woman's Hospital, Chicago. Third Edition. Over 160 Illus- trations. Octavo. Cloth, 5.00 ; Leather, 6.00 "The treatise is as complete a one as the present state of our science will admit of being written. We commend it to the diligent study of every practitioner and student, as a work calculated to in- culcate sound principles and lead to enlightened practice." — New York Medical Record. Cazeaux and Tarnier. Obstetrics ; the Theory and Practice of; including the Diseases of Pregnancy and Parturition, Ob- stetrical Operations, etc. By P. Cazeaux, Member of the Impe- rial Academy of Medicine, etc. Revised, with additions, by S. Tamier, Prof, of Obstetrics and Diseases of Women and Children in the Faculty of Medicine, of Paris. A New Ameri- can, from the Eighth French and First Italian Editions. Edited and enlarged by Robert J. Hess, m.d., Physician to the North- ern Dispensary, Philadelphia; Member of the College of Physi- cians of Philadelphia, etc. 1100 pages, 4to, with 12 Full-page Lithographic plates, 5 of which are Colored, and over 175 Wood Engravings. Sold by subscription only. Full information and Four-page Circular upon application to the publishers. Galabin's Midwifery. A New Manual for Students. By A. Lewis Galabin, m.d., f.k.c.p., Obstetric Physician to Guy's Hospital London, and Professor of Obstetrics in the same Insti- tution. 227 Illustrations Cloth, 3.00; Leather, 3.50 Rigby's Obstetric Memoranda. By Alfred Meadows, m.d. 4th Edition. Cloth, .50 $$* See pages 2 to 5 for list of ? Quiz- Commends f STUDENTS' TEXT-BOOKS AND MANUALS. It Obstetrics and Gynecology: — Continued. Meadows' Manual of Midwifery. Including the Signs and Symptoms of Pregnancy, Obstetric Operations, Diseases of the Puerperal State, etc. 145 Illustrations. 494 pages. Cloth, 2.00 Swayne's Obstetric Aphorisms. For the use of Students commencing Midwifery Practice. 8th Ed. izmo. Cloth, 1.25 PATHOLOGY AND HISTOLOGY. Rindfieisch's General Pathology. For Students and Physi- cians. By Prof. Edward Rindfleisch, of Wurzburg. Trans- lated by Wm. H. Mercur, m.d., of Pittsburg, Pa., Edited by James Tyson, m.d., Professor of Pathology and Morbid Anatomy in the University of Pennsylvania. 12R10. Cloth, 2.00 Gilliam's Essentials of Pathology. A Handbook foi Students. 47 Illustrations. i2mo. Cloth, 2.00 *#*The object of this book is to unfold to the beginner the funda- mentals of pathology in a plain, practical way, and by bringing them within easy comprehension to increase his interest in the study of thesubject. Though it will not altogether supplant larger works, it will be found to impart clear-cut conceptions of the generally accepted doctrines of the day, and to prevent confusion in the mind of the student. Gibbes 1 Practical Histology and Pathology. Third Edition. Enlarged. i2mo. Cloth, 1.75 PHYSICAL DIAGNOSIS. Bruen's Physical Diagnosis of the Heart and Lungs. By Dr. Edward T. Bruen, Assistant Professor of Clinical Medicine in the University of Pennsylvania. Second Edition, revised. With new Illustrations. i2mo. Cloth, 1.50 *#* The subject is treated in a plain, practical manner, avoiding questions of historical or theoretical interest, and without laying special claim to originality of matter, the author has made a book that presents to the student the somewhat difficult points of Physi- cal Diagnosis clearly and distinctly , PHYSIOLOGY. Yeo's Physiology. The most Popular Students' Book. By Gerald F. Yeo, m.d., f.r.c.s., Professor of Physiology in King's College, London. Small Octavo. 750 pages. Over 300 carefully printed Illustrations. With a Full Glossary and Index. Cloth, 4.00 ; Leather, 5,00 " The work will take a high rank among the smaller text-books of Physiology."— -Prof. H. P. Boivditch, Harvard Med. School, Boston. " The brief examination I have given it was so favorable that I placed it in the list of text-books recommended in the circular of the University Medical College." — Prof. Lewis A. Stimpson, M. D. t 37 East 33d Street , New York. 4E5 3 - See pages 3 to 5 for list 0/ f Quiz- Compends ? 12 STUDENTS' TEXT-BOOKS AND MANUALS. Physiology ; — Continued. Kirke's Physiology, nth Ed. Illus. Cloth, 4.00 ; Leather, 5.00 Landoi s ' Human Physiology. Including Histology and Micro- scopical Anatomy. 2 volumes. Cloth, 10.00 " So great are the advantages offered by Prof. Landois' Text- book, from the exhaustive and eminently practical manner in which the subject is treated, that, notwithstanding it is one of the largest works on Physiology, it has yet passed through four large editions in the same number of years. Dr. Stirling's annotations have materially added to the value of the work. . . . Admirably adapted for the practitioner. . . . With this Text-book at his command, no student could fail in his examination.*' — Lancet. Sanderson's Physiological Laboratory. Being Practical Ex- ercises for the Student. 350 Illustrations. 8vo. Cloth, 5.00 Tyson's Cell Doctrine. Its History and Present State. Illus- trated. Second Edition. Cloth, 2.00 PRACTICE. Roberts' Practice. Fifth American Edition. A Handbook of the Theory and Practice of Medicine. By Frederick T. Roberts, m.d. ; m.r.c.p., Professor of Clinical Medicine and Therapeutics in University College Hospital, London. Fifth Edition. Octavo. Cloth, 5.00; Leather, 6.06 *#* This new edition has been subjected to a careful revision. Many chapters have been rewritten. Important additions have been made throughout, and new illustrations introduced. Recom- mended as a Text-book at University of Pennsylvania, Long Island College Hospital, Yale and Harvard Colleges, Bishop's College, Montreal, University of Michigan, and over twenty other Medical Schools. " I have become thoroughly convinced of its great value, and have cordially recommended it to my class in Yale College." — Prof. David P. Smith. " I have examined it with some care, and think it a good book and shall take pleasure in mentioning it among the works which may properly be put in the hands of students." — A. B, Palmer, Pro/, of the Practice of Medicine, University of Michigan. " A clear, yet concise, scientific and practical work. It is a capi- tal compendiun of the classified knowledge of the subject." — Prof. % Adams Allen, Rush Medical College, Chicago. " It is unsurpassed by any work that has fallen into our hands, as a compendium for students preparing for examination. It is thoroughly practical, and fully up to the times." — The Clinic. Aitken's Practice of Medicine. Seventh Edition. 196 Illus- trations. 2 vols. Cloth, 12.00; Leather, 14.00 Fagge's Principles and Practice of Medicine. A Complete Text-book. 2 vols. Now Ready. Tanner's Index of Diseases, and Their Treatment. Cloth, 3.00 " This work has won for itself a reputation. ... It is, in truth, what its Title indicates. "—N. Y. Medical Record. ■6&~ See pages 2 to j for list of ? Quiz-Compends ? STUDENTS' TEXT-BOOKS AND MANUALS. 13 PRESCRIPTION BOOKS. Wythe's Dose and Symptom Book. Containing the Doses and Uses of all the principal Articles of the Materia Medica, etc. Sixteenth edition. 32mo. Cloth, i.oo; Pocket-book style, 1.25 Pereira's Physician's Prescription Book. Containing Lists of Terms, Phrases, Contractions, and Abbreviations used in Prescriptions, Explanatory Notes, Grammatical Construction of Prescriptions, etc., etc. By Professor Jonathan Pereira, m.d. Sixteenth Edition. 32mo. Cloth, 1.00; Pocket-book style, 1.25 SKIN DISEASES. Van Harlingen on Skin Diseases. A Handbook of the Dis- eases of the Skin, their Diagnosis and Treatment. By Arthur Van Harlingen, m.d., Prof, of Diseases of the Skin in the Phila- delphia Polyclinic; Consulting Physician to the Dispensary for Skin Diseases, etc. With colored plates. i2mo. Cloth, 1.75 ***This is a complete epitome of skin diseases, arranged in alphabetical order, giving the diagnosis and treatment in a concise, practical way. Many prescriptions are given that have never been published in any text-book, and an article incorporated on Diet. The plates do not represent one or two cases, but are composed of a number of figures, accurately colored, showing the appearance of various lesions, and will be found to give great aid in diagnosing. " This new handbook is essentially a small encyclopaedia. * * * We heartily commend it for its brevity, clearness and evidently careful preparation." — Philadelphia Medical Times. " This is an excellent little book, in which, for ease of reference, the more common diseases of the skin are arranged in alphabetical order, while many good prescriptions are given, together with clear and sensible directions as to their proper application." — Boston Medical and Surgical Journal. Bulkley. The Skin in Health and Disease. By L. Duncan Bulkley, Physician to theN. Y. Hospital. Illus. Cloth, .50 SURGERY. Heath's Minor Surgery, and Bandaging. New Edition. With many Illustrations. In Press. Mears' Practical Surgery. Second Edition. Enlarged. 490 Illustrations. Cloth, £3.75 ; Leather, $4.75 Pye's Surgical Handicraft. A Manual of Surgical Manipula- tions, Minor Surgery, Bandaging, Dressing, etc., etc. With special chapters on Aural Surgery, Extraction of Teeth, Anaes- thetics, etc. 208 Illustrations. 8vo. Cloth, 5.00 Watson on Amputation of the Extremities, and their Compli- cations. 2 colored plates and 250 wood cuts. 8vo. Cloth, 5.50 4®- See flages 2 to sfor list of ? Quiz-Compends ? 14 STUDENTS' TEXT-BOOKS AND MANUALS. THROAT. Mackenzie on the Throat and Nose. By Morell Mackenzie, m.d., Senior Physician to the Hospital for Diseases of the Chest and Throat; Lecturer on Diseases of the Throat at the London Hospital, etc. Vol. I. Including the Pharynx, Larynx, Trachea, etc., with Formulae and 112 Illustrations. Vol. II. Diseases of the Oesophagus, Nose and Naso-Pharynx, with Formulae and 93 Illustrations. The two volumes. Cloth, 6.00; Leather, 7.50 Vol. II, separately, Cloth, 3.00; Leather, 4.00 " It is both practical and learned ; abundantly and well illustrated ; its descriptions of disease are graphic and the diagnosis the best we have anywhere seen." — Philadelphia Medical Times. Cohen. The Throat and Voice. Illustrated. Cloth, .50 James. Sore Throat. Its Nature, Varieties and Treatment. i2tno. Illustrated. Paper cover, .75; Cloth, 1.25 URINE AND URINARY ORGANS. Acton. The Reproductive Organs. In Childhood, Youth, Adult Life and Old Age. Sixth Edition. Cloth, 2.00 Beale. Urinary and Renal Diseases and Calculous Disorders. Hints on Diagnosis and Treatment. i2mo. Cloth, 1.75 Ralfe. Kidney Diseases and Urinary Derangements. 42 Illus- trations. i2mo. 572 pages, y-ust Ready. Cloth, 2.75 Legg. On the Urine. A Practical Guide. 6th Ed. Cloth, .75 Marshall and Smith. On the Urine. The Chemical Analysis of the Urine. By John Marshall, m.d., Chemical Laboratory, University of Pennsylvania, and Prof. E. F. Smith, ph.d. With Colored Plates. Cloth, 1.00 Thompson. Diseases of the Urinary Organs. Seventh Edition. Illustrated. Cloth, 1.25 Tyson. On the Urine. A Practical Guide to the Examination of Urine. By James Tyson, m.d., Professor of Pathology and Morbid Anatomy, University of Penn'a. With Colored Plates and Wood Engravings. 5th Ed. Enlarged. 12010. Cloth, 1.50 VENEREAL DISEASES. Hill and Cooper. Student's Manual of Venereal Diseases. Fourth Edition. 121110, Cloth, i.co Durkee. On Gonorrhoea and Syphilis. Illus. Cloth, 3. So ^®* See pages 2 to S/or list of ? Quiz- Compends ? Richter's Chemistries. AUTHORIZED TRANSLATIONS. By EDGAR F. SMITH, M.A., Ph.D., Prof, of Chemistry in Wittenberg College, Springfield, Ohio ; formerly in the Laboratories of the University of Pennsylva- nia and Muhlenburg College; Member of the Chemical Societies of Berlin and Paris ; of the Academy of Natural Sciences of Philadelphia t etc., etc. EACH VOLUME SOLD SEPARATELY. INORGANIC CHEMISTRY. Second American, from the Fourth German Edition; thoroughly revised and in many parts rewritten. With 89 Illustrations and Colored Plate of Spectra. Cloth, $2,00 THE CHEMISTRY OF THE CARBON COM- POUNDS, or Organic Chemistry. First Ameri- can, from Fourth German Edition. Illustrated. Cloth, #3.00 The success attending the publication of the first edi- tion of Richter's Inorganic Chemistry encourages the translator and publishers to believe that the companion volume will have an equally warm reception. Professor Richter's methods of arrangement and teaching have proved their superiority, abroad, by the very large sale of his books all over the Continent, translations having been made in Germany, Russia, Holland and Italy. From Phof. B. Silliman, Yale College, New Haven, Conn. " It is decidedly a good book, and in some respects the best manual we have.'* From John Marshall, m.d., nat. sc. d. (Tubingen), Demonstra- tor of Chemistry in the University of Pennsylvania, Medical Department. " The work is of undoubted value. The theory of chemistry, which is generally the bugbear of students, is, in this book, very clearly explained, and the explanations are so well distributed through the book that students are brought easily from the simplest to the most difficult problems. "That part descriptive of the elements and their compounds is full, and all that could be desired in a text-book, while the cuts, with which the work is profusely illustrated, are an excellent aid to the student. Altogether, it is one of our best modern works on chemistry." Yeo's Physiology. A MANUAL FOR STUDENTS. By GERALD F. YEO, M.D., F.R.C.S., Professor of Physiology in King's College, London. WITH OVER 300 CAREFULLY PRINTED ILLUSTRA- TIONS AND A GLOSSARY. Small Octavo. Cloth, $4.00; Leather, $5.00. RECOMMENDATIONS. " After a careful examination of this manual of Physiology, I can truthfully s*ay that it is a most valuable addition to the list of text- books upon this subject. That it should and will receive a welcome from both students and teachers there can be no doubt; for, in addi- tion to the familiar but well presented facts of most text-books, it contains all the more important facts of physiological science which have been established in the last few years. The author presents his subject in a manner that is clear, concise and logical. Each section has had a careful revision, and reveals the author's famili- arity with the scope and tendencies of modern physiology. It will prove an interesting and instructive book to those commencing the study of this subject." — A. P. Brubaker, m.d., Demonstrator of Physiology at Jefferson Medical College, Philadelphia. •'The writer has endeavored to * avoid theories which have not borne the test of time, and such details of methods as are unnecessary for junior students.' His experience as a teacher and as an ex- aminer has led him to lay stress on the points which are hard to grasp and are commonly misunderstood, and he has directed atten- tion more to those subjects which have a practical medical or surgi- cal application than to those relating to abstract physiological subjects. * * * We have pleasure in recommending this book, as a most excellent manual, being what it pretends to be— relementary, and yet containing all that is really cf importance to the student of medicine. It is difficult to devise an original method of treating such a well worn subject as physiology, but the present volume undoubtedly has originality in its method. We think the author treats his subject in the best manner possible when he combines microscopical anatomy intimately with the discussion of strict phy- siology.'* — The Medical Times and Gazette. ■■■ . •:■■ ■