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IN offering to the British public the present translation of the latest work of Baron Liebig, I may be permitted to say, that I feel highly honoured in being intrusted with the duty of conveying to my countrymen a knowledge of one of the most interesting and valuable investigations which has yet been made in Animal Chemistry. The researches into the nature of the soluble constituents of muscle or flesh, which constitute the chief part of the present work, are preceded by considerations on the true Method of Research in Animal Chemistry, which are worthy of the most earnest attention on the part of those who intend to devote themselves to investigations in this most important and at the same time most difficult department of science. A careful study of this section will convince the reader that much more might have been done of late years in Physio- logical Chemistry, but for the wrong direction unfortunately given to recent researches, and will 140 VI EDITORS PREFACE. powerfully contribute to direct into the right channel the energies of those rising chemists to whom Britain must look to sustain her scientific reputation in the present age of rapidly advancing discovery in the most recondite parts of Organic Chemistry and of Physiology. The physiologist will also find in this introductory section, the most convincing reasons to show that, henceforth, it is indispensable that Anatomy, struc- tural Physiology, and Chemistry should unite their forces with a view to the solution of the great ques- tions which it is the common object of these sciences to solve. With regard to the chemical researches contained in the present work, it is most emphatically to be stated, that they constitute only the first steps in an almost new career ; that they are very far from exhausting even the single subject here investigated, namely, the nature of the soluble constituents of the muscles; and that, consequently, they are chiefly valuable as indicating the true path at present to be pursued by chemists. It would be contrary to the principles as well as to the wishes of their author, if physiologists were to regard them as completed, or as in any one point exhausting the subject ; and how many more subjects does the animal organism present, which must remain obscure and impe- EDITOR'S PREFACE. vn netrable till they shall be studied on principles analogous to those which have guided the author ? Nevertheless, these researches have already thrown much light on many important but obscure questions ; and independently of the interest which, in a purely chemical view, they must always have for the chemist, they will be found, by the physiolo- gist and the medical man, both interesting and valuable in a very high degree. In connection with previous researches, they serve to demonstrate, that the more we know of the processes going on in the organism, the more do we find these to involve strictly chemical changes, and to be capable of a chemical interpretation. It would indeed appear as if every change in the organism were attended by a' definite chemical or physical action ; and although we shall probably never succeed in unveiling the nature of the pecu- liar influence, called vitality, under which these changes occur, yet the present as well as previous investigations render it certain that we have still a great deal more to discover concerning the share taken by chemical action in the vital processes. I cannot omit to direct the attention of physio- logists to the proofs, contained in the following pages, of the truth of the principle, that every property, however apparently trifling or minute, Viii EDITOR S PREFACE. possessed by any constituent of the organism, even by such as occur only in very small proportion, has its destined use and function; and, consequently that every constant difference, whether of composi- tion, of form, or of quality, in the different tissues and fluids, must likewise correspond to a difference of function, in which, as a general rule, it cannot be replaced, nor its absence compensated for, by any other substance, however analogous in most of its properties. A striking example of this truth will be found in the facts concerning the great preponderance of phosphate of potash and chloride of potassium in the juice of flesh, while in the blood and lymph which circulate through the muscles, it is phosphate of soda and chloride of sodium which prevail. Another will be found in the fact that the juice of flesh is always strongly acid, while the blood and lymph are decidedly alkaline ; and a third is seen in the abundant supply of lactic acid in the juice of flesh, while it cannot be detected in the urine. But perhaps the most interesting observation, next to the discovery of kreatine as a constant ingredient of flesh, of kreatinine, a powerful base, in the juice of flesh, and of both in urine, is the demonstration, complete, as it appears to me, of the true function of the phosphate of soda in the blood. EDITORS PREFACE. IX This function, that of absorbing carbonic acid and giving it out in the lungs, is here shown to depend entirely on the minute chemical characters of the salt in question ; and we now see how it happens that phosphate of soda is essential to the blood, and cannot be replaced by phosphate of potash, a salt, which, although in many points analogous, differs entirely from phosphate of soda, in its ten- dency to acquire an acid instead of an alkaline reaction, and in its relation to carbonic acid. In this way, the beautiful researches of Graham on the phosphates are now finding their application, in the minutest point, to physiology. The same remark applies to the action of common salt on phosphate of potash, which satisfactorily accounts for the presence of phosphate of soda in the blood of animals whose food contains only phosphate of potash, but which either find common salt in their food, or obtain it as an addition. Surely such facts as these must convince all men of the value of the most minute study of the chemical properties of all the substances which occur in the organism, however these properties may at first appear trifling or unimportant ; and of the utter impossibility of making progress in Physiology without the aid of Chemistry. I would also direct attention to the evidence here given of the fact, that the parietes of X EDITORS PREFACE. the different systems of vessels, as well as the mem- branes and cells, must possess, in the living body, a power of selection, or, in other words, different degrees of permeability, in reference to the various substances which penetrate them by endosmose. To this subject the investigations of the Author have been more particularly directed, since the termination of the present work ; and results of great interest and value have been already obtained. The medical man will find in these Researches a prospect of many and great improvements in practice, whether as regards dietetics, or the ac- tion of acids, alkalies, and salts on the digestive and respiratory processes ; and with respect to both, it is to Chemistry that he must look for as- sistance in his efforts to advance. Lastly, the present work contains some most valuable prac- tical applications of the chemical discoveries therein detailed, to an art which immediately concerns the whole of mankind ; namely, the culinary art. The subjects of the preparation of meat for food by boiling, roasting, and stewing ; the true nature and proper mode of preparation of soup, as well as of the extract of flesh or genuine portable soup ; and, finally, the changes produced in meat, not only by the above processes, but by salting, and the conditions necessary in each case to insure EDITOR S PREFACE. XI the digestibility and nutritive qualities of the flesh or soup, are here, for the first time, investigated on scientific principles; and in all these points, Che- mistry is found to be the means of throwing light on that which was obscure, and of improving our practice by the application of rational principles. In conclusion I would remark, that the apparent simplicity of the results, and even of the processes described, gives a very inadequate idea of the laborious and difficult nature of the investigation. Having myself repeated several of these processes, I have been enabled to perceive, that, unless Baron Liebig had devoted to the subject his whole en- ergies for a long time, and unless, moreover, he had operated on a scale so large as few experi- menters would have ventured on, the whole subject would have remained as obscure as ever. Not the least valuable lesson to be derived from this work is the absolute necessity of experimenting on a very large scale, if we would obtain satisfactory or trustworthy results. WILLIAM GREGORY. UNIVERSITT OF EDINBURGH, 31st May, 1847. AUTHOR'S PREFACE. THE preparation of a new edition of my Animal Chemistry rendered it desirable, and even necessary, to subject to an experimental inquiry and criticism the chemical observations made, up to that period, in this department of the science. I was thus induced to engage in a series of researches, which have led me farther than I at first anticipated. The questions as to the nature of the organic acid diffused through the muscular system, and that of the other sub- stances contained in that system, appeared to me so important for the right understanding and explana- tion of the vital processes, that I did not feel justi- fied in proceeding with the revisal of my work until these questions had been, at least to a certain extent, experimentally answered. The present little work contains the analytical details of my investigation on these subjects, which, in accordance with the plan of the Animal Che- mistry, could not be introduced into that work. AUTHOR S PREFACE. As my experiments include the changes which flesh undergoes in its preparation for food, I trust that not only physiologists and chemists, but also the lovers of a rational system of diet, will find in the following pages many observations worthy of their attention. DR. JUSTUS LIEBIG. GIESSEN, 1st June, 1847. CONTENTS. SECTION I. On the methods of investigation to be pursued in Animal Chemistry ... ... ... ... * page 1 Want of connection between Chemistry and Physiology ... 4 Animal tissues and compounds act as ferments ... ... 7 The changes going on in the body are little known ... 10 The results of ultimate analysis of animal substances have been unsatisfactory ... ... ... ... ... ib. Necessity for control to ultimate analysis ... ... 12 Erroneous methods of control adopted ... ... ... 13 Mulder's theory of Proteine ... ... ... ... 15 It is not tenable ... 16 Theories are never absolutely true, but only true for the period ... ... ... ... ... ... ... 18 Fallacious conclusions drawn from the analysis of fibrine, albumen, &c. ... .. ... ... ... ... 19 Identity of composition not necessary ... ... ... 21 Erroneous views deduced from the Proteine theory ... ib. Proteine does not exist ... ... ... ... ... 25 There is much to be done in regard to the constitution of fibrine, albumen, &c. ... ... ... ... ... 27 SECTION II. Acid reaction of the juice of flesh ... ... ... 28 Observations of Berzelius on the juice of flesh ... ... ib. The presence of lactic acid in it doubtful 31 Kreatine discovered by Chevreul, in 1835 32 His account of it , 33 XVI CONTENTS. Berzelius on kreatine ... ... ... ... 34 Wohler and Schlossberger on kreatine 35 Investigation of the juice of flesh ... 37 Extraction of the soluble constituents of flesh 38 It is necessary to use large quantities ... ... ... 39 Game and fowl yield most kreatine ... ... ... 41 The liquid always acid, even when mixed with blood ... ib> Separation of the phosphoric acid ... ... 4 2 Modification of the process for fish ... 44 Kreatine crystallises ... ! vi l . ; ... ... ... ib. Its amount in different kinds of flesh ... ... ... 45 It occurs in all the higher animals... ... ... ... 46 Kreatine 47 Analysis of kreatine ... ... ... ... ... 48 Properties of kreatine ... ... ... ^.. ... 51 Action of acids and bases on it ... ... ... ... 52 Kreatinine, its preparation ... ... ... ... 53 Its properties ... ... ... ... ... ... 55 It is a powerful base ... ... ... ... ... 56 Its composition ... ... ... ... ... ... 57 Its relation to kreatine ... ... ... ... ... 58 Analysis of kreatinine ... ... ... ... ... 59 Kreatine and kreatinine in urine ... ... ... ... 60 Pettenkofer's compound ... ... ... ... ... ib. Improved method of preparing it ... ... ... ... 61 It consists of kreatinine and kreatine f< ^:, 7; ,^,, ... 64 Kreatinine alone is found in putrid urine ... ;.-. ^^ *^ Salts of kreatinine ... ... ... ., ... ... 66 Sarcosine, its preparation ... ...-,* ..-*> ... .. 68 Its properties ,,i?f-: 69 Its analysis ... ... ... ... ... ... 70 Salts of sarcosine ... ... ... ... ... ib. Its formula ... ... 74 Its relation to kreatine 75 It is isomeric with lactamide and with urethane 76 Inosinic acid, its preparation ... *?$&'?* 77 Its analysis -' .vr 79 Its formula "'"?&+' ... > 80 Inosinates ib. CONTENTS. XV11 Probable constitution of the acid ... ... ... ... 84 Kreatinine exists ready formed in flesh ... ... 85 Lactic acid, as a" constituent of flesh ... ... 88 Method of extracting it ... ... ... ... ... ib. Modification of the process for fish ... ... ... 90 Analysis of lactates from flesh and fish ... ... ... 91 Inorganic constituents of the juice of flesh ... ... 93 Large amount of inorganic salts in flesh ... ... ... ib. Large proportion of soluble phosphates ... ... ... 94 The ashes of flesh contain no carbonates, only phosphates and chlorides ... ... ... ... ... ... 95 The different modifications of phosphates are present in these ashes ... ... ... ... ... ... ib. Characters of the phosphates ... ... ... ... ib. In certain kinds of flesh, the whole alkalies are not sufficient to form tribasic phosphates ... ... ... .. 98 In fowl, they are not sufficient even to form bibasic phos- phates ... ... ... ... ... ... ... ib. Equilibrium between the free lactic and phosphoric acids in the juice of flesh... ... ... ... ... ... 99 The ashes of flesh always alkaline ... ... ... 100 Importance of these facts in explaining the vital processes ib. Lactic acid cannot be detected in normal urine, whether it be acid or alkaline ... ... ... ... ... 101 It is therefore consumed in the respiratory process, and in this form sugar, starch, &c. are employed in respiration 103 The blood and lymph are always alkaline, the juice of muscle always acid ... ... ... ... ... 104 These conditions may give rise to electrical currents ... ib. The juice of flesh contains phosphate of potash and chloride of potassium ... ... ... ... ... ... ib. While blood and lymph contain phosphate of soda and chloride of sodium ... ... ... 105 Relative proportions of soda and potash in the juice of flesh and in blood ... ... ... ... ... ... ib* The juice of flesh, if it could be obtained free from blood and lymph, would perhaps contain no soda 107 The permeability of the vessels for the different fluids must be different ib. b XV111 CONTENTS. Morbid accumulation of free acid destroys the bones ... 108 Importance of chloride of sodium as a part of the food of animals ... ... ... ... ... ib. Inland plants contain only salts of potash 109 Maritime and even sea plants contain much more potash than soda ... ... ... ... ... ... ib. Mutual action of phosphate of potash and chloride of sodium ... ... ... ... ... ... ... 110 It produces phosphate of soda ... ... ... ... Ill Phosphate of soda is indispensable to the blood ... ... 112 Its importance in respiration ... ... ... ... ib. Relation of blood to carbonic acid gas ... ... ... ib. Its absorbent power is not owing to the presence of carbon- ate of soda 113 Experiments to prove this ... ... ... ... ... 114 Remarkable properties of phosphate of soda, to which the blood owes its power of absorbing and giving off carbonic acid 117 The study of the influence of salts, acids, and alkalies on respiration and digestion will lead to valuable results in medicine ... ... ... ... ... ... ... 1 20 Relative proportions of lime and magnesia in the juice of flesh ib. SECTION III. General results . r 122 Practical applications to cookery ... ... ... ... ib. Action of cold water on flesh ... ... ... ... 123 Stock contains the soluble constituents of flesh ... ... ib. Nature of soup ib. Albumen in flesh ... ... ... ... ... ... 125 It is the cause of tenderness ... ... ... ... ib. Action of hot water on flesh 126 Best method of boiling meat ... ... ... ... ib. Temperature required ... ... ... ... ... ib. Underdone meat ... ... ... ... ... ... 127 Poultry sooner done than beef or mutton ... ... ib. CONTENTS. XIX Use of a covering of lard in roasting ... ... ... 127 Best method of boiling meat to obtain soup from it ... 128 The bouilli is neither nutritious nor digestible without the soup ... ... ... ... ... ... ... ib. Gelatine not the source of the strength or flavour of soup ib. Amount of gelatine dissolved by boiling water ... ... 129 Amount of matter dissolved by cold water ... ... 130 Poultry contains much soluble matter ... ... ... 131 The nutritious and sapid ingredients of soup exist in it ready formed ... ... ... ... ... ... ib. Best mode of preparing soup ... ... ... ... ib. Influence of the colour of soup on our judgment of its taste 132 Extract of meat, or true portable soup ... ... ... ib. The portable soup of commerce is nearly pure gelatine ... ib. Beef yields 1- 32nd of extract 133 Extract of meat recommended as a restorative for wounded persons ... ... ... ..: ... ... ... ib. Characters of true and false extract ... ... ... ib. Extract of meat will be useful in ships, fortresses, &c., where much salt meat is consumed ... ... ... 134 Salting of meat ... ... ... ... ... ... ib. The brine contains the soluble ingredients ... ... ib. Salt meat is therefore deficient in nutritive qualities ... 135 Causes of this ... ... ... ... ... ... ib. Effects produced by salt, containing chlorides of calcium and magnesium ... ... ... ... ... ... 135 Meat salted with such salt may be less unwholesome ... ib. Flesh compared with ther animal food 137 The soluble constituents of muscles must be essential to their functions ... ... ... ... ... ... /#. Lactic acid exists in the gastric juice ... ... ... 138 The digestive process, in a chemical point of view, now cleared up ... ... ... ... ... ... /. The gastric juice resembles the juice of flesh .. ... ib. Soup or extract of flesh suggested as a remedy for dyspepsia, and for convalescents 139 Origin of hydrochloric and other volatile acids in the gastric juice ;# t XX CONTENTS. CONCLUSION. These researches are only the commencement of what must be an extensive series ... ... ... ... ... 139 Various substances distinguishable in the muscular sub- stance ... ... ... ... ... ... ... 140 True province of chemical analysis ... ... ... ib. Kreatine and kreatinine, occurring both in muscle and in urine, must serve some purpose in the organism, not yet ascertained ... ... ... ... ... ... 141 There is a gelatinous substance, not gelatine, in the cold infusion of flesh, not yet studied ... ... ... ib. Also a body resembling caseine, not yet examined ... ib. Also, two new nitrogenised acids not yet investigated . . . ib. The juice of flesh appears to contain neither urea nor uric acid "''~r.'f l ... 142 But on one occasion the author obtained a trace of a sub- stance resembling uric acid ib. RESEARCHES CHEMISTRY OF FOOD, SECTION I. INTRODUCTORY, On the Methods of Investigation in Animal Chemistry. IF we consider with some attention the facts chemists have not which have been ascertained in Animal Chemistry, devoted we shall be surprised to find how few among them giestoAni- there are, on which conclusions can be securely mistry and based. The cause of this appears to me to be, that hitherto but a very small number, comparatively, of professional chemists have occupied themselves with the cultivation of this department of the science, or have selected it as the object of profound and thorough investigation. The important researches which Berzelius began forty years ago, as well as those of L. Gmelin, Braconnot, and Chevreul, have not been imitated or followed up in the same spirit which animated these men. No chemist has yet appeared who' has chosen, in Animal Physiology, as De Saussure did in Vegetable Physiology, the first B Z METHODS OF INVESTIGATION and most important questions as the problem of his life. Hence it comes, that in Animal Chemistry, Animal which is a frontier district, belonging entirely nei- Chemistry J has been in ther to Chemistry nor to Physiology, as commonly of adven- happens on the frontiers of thinly-peopled countries, adventurers of all kinds roam about ; and it is on the observations made, and the tales related by these adventurers, during their occasional expedi- tions or excursions, that the greater part of our knowledge of this district rests. But how few of them have attained so accurate a knowledge, even of the small tract over which they have passed, that those who follow them run no risk of losing their way ! It is one thing to travel through a country, and another, very different, to establish a home therein. Conse- Since none of those philosophers who are called this. to possess this country, and who should draw from its fertile soil useful fruits, in the form of prolific points of view, and imperishable truths, takes the trouble to follow the devious path of these adven- turers, and to test the accuracy of their statements, they are induced, either to reject all these tales as vague and unfounded, or to regard them as actual truths. If one experimenter, for example, has found, in this or in that quarter, nothing which seemed worthy of his attention, they conclude that there is nothing whatever to be found there ; and if another proclaims the rich treasures of a different district, they act as if they were already in posses- IN ANIMAL CHEMISTRY. 3 sion of these ; they build bridges over rivers, and drive mills with their waterfalls ; but these are bridges over which no one passes, and mills that yield us no flour. For centuries past, men have endeavoured to dis- Exploded cover methods of cure, or a knowledge of morbid medical , conditions, by the aid of the imagination, in the so- called systems of medicine ; as if it were possible, or even wise and judicious, to expect a true insight into these things, or to look for intellectual illu- mination and progress from the most hazardous of all games of chance. In modern times this method has been abandoned The che- as entirely unproductive ; but, on the other hand, direct mte- . ! . T restinPhy- men commit an error not less grave, inasmuch as, sioiogy and instead of acquiring by their own researches the knowledge necessary for the solution of their diffi- culties, they leave this duty to others, who, fully occupied with the cultivation of their own branch of science, have neither interest in the questions to be solved, nor inclination for the task. From the chemical analysis of blood, of urine, or of a morbid product, they expect an aid which these analyses can never afford, as long as the results of the che- mist are not brought into the true connection with the conditions which they are to explain, or with the causes which have produced these conditions. All the new facts daily ascertained by the chemist Pathoio- gists neg- are regarded by pathologists as being exactly those lect pure which are of no direct use to them, because they B2 METHODS OF INVESTIGATION Erroneous views in re- gard to the nature of the connec- tion be- tween me- dicine and chemistry. Want of mutual connection between chemistry and physi- ology, have no clear idea of that which they require ; be- cause they are unable to connect with these chemi- cal discoveries any question to be solved, or to draw from them any conclusion. What an inconceivable delusion, what a confusion of ideas must exist, when a physician thinks, that from the complex results of an analysis of the blood, he can draw a conclusion as to the nature and the cause of a disease, and can found on this a method of treatment, when we have not yet advanced so far in physiology as to bring into relation with the digestive process one of the simplest chemical facts, namely, the absence of alkaline phosphates in the urine of the herbivora ! What pathologist has ever yet attempted to fix and define the notion of bad or spoiled food, in its full signification, by means of a logical comparison with good and wholesome food ? and yet the former are regarded as the proximate causes of diseased conditions. I readily admit, that for such an investigation chemical knowledge is indispensable ; but the investigation itself has no value in reference to chemistry, and constitutes no object of research for the chemist, as such. From this state of things, which depends on the want of connection between the labours of chemists and those of physiologists, it has happened, that Animal Chemistry, during the last ten years, has gained little more than a more accurate knowledge of those compounds which the animal organism applies to no further purpose in its economy ; and IN ANIMAL CHEMISTRY. i> that, at the present time, it seems as if all the won- derful properties which it exhibits were produced only by means of albumen, fibrine, gelatine, some cerebral or nervous matter, and a little bile. It is has greatly universally felt, that we are as far from a true ani- an imaiche- mal chemistry as the anatomy of the last century E was from the physiology of the present day. In- deed the animal chemistry of our time cannot be compared to modern anatomy, since microscopic researches have established the existence of struc- tures which had entirely escaped the earlier investi- gators ; of structures, as is now known, on which alone the function of those formerly observed depends. We know that the aliments of all plants are pre- Varied re- cisely the same ; but what a multitude of forms do ge tation these assume in the organisms of different plants ! The same soil on which we grow grain, beet-root, or potatoes, yields also tobacco and poppies. In grain and potatoes we have starch, in beet-root, sugar, in all three, a certain amount of compounds containing sulphur and nitrogen ; in the poppy, a fat oil and a series of organic bases, containing nitrogen, but not sulphur, which are not found in other families of plants ; in tobacco, a volatile oil, containing nitrogen, possessed of basic or alkaline properties. These substances, so different in composition, are all derived from the same compounds, which nature supplies as food to all plants. It is certain that the 6 METHODS OF INVESTIGATION must de- pend on differences of organ- isation in plants. The varied secretions of the ani- mal body must de- pend on similar causes ; not yet studied. differences in the nature and composition of these products can only be determined by variations in the organisation of the plants which produce them ; for they are the visible signs of existing peculiar agencies, and chemistry, which has succeeded in detecting so great a variety in these compounds, belonging only to certain vegetable families, has thus, in her department, surpassed vegetable ana- tomy. But the case is entirely reversed, when we compare the progress of animal anatomy with that of animal chemistry. The chemical relations which must correspond to the different structures and tis- sues are altogether unexamined ; and yet we cannot suppose otherwise than that the nature of each secretion must stand in a definite relation of de- pendence, in reference to its composition and its chemical properties, with those of the substance from which it is formed, or with those of the parts which are concerned in its formation. If we suppose, that it is from the blood that all the constituents of the animal body are formed, this can only take place in virtue of certain forces, which belong, not to the blood, but to the organs in which the component parts of the blood are employed to produce them. The direction and position, the peculiar arrangement of the elements of the consti- tuents of the blood in the process of nutrition, are changed according to these seats of peculiar direc- tion in the force acting in the body, which have the same relation to the blood as the different vegetable IN ANIMAL CHEMISTRY. 7 families have to the analogous substances which they receive as food from the air and the soil. There is, probably, no fact more firmly established, Agency of decompos- as to its chemical signification, than this, that the ing animal chief constituents of the animal body, albumen, pounds, fibrine, the gelatinous tissues, and caseous matter, when their elements are in a state of motion, that is, of separation, exert on all substances which serve as food for men and animals, a defined action, the visible sign of which is a chemical alteration of the substance brought in contact with them. That the elements of sugar, of sugar of milk, of Transform- starch, &c., in contact with the sulphurised and pending on nitrogenised constituents of the body, or with the sem-eof analogous compounds which occur in plants, when these are in a state of decomposition, are subjected to a new arrangement, and that new products are formed from them, most of which cannot be pro- duced by chemical affinities, this is a fact, independ- ent of all theory. Chemical affinities exert an in- fluence on the nature of the new products, but do Agency of not determine their formation. The cause of this compared is obvious. When an organic substance is decom- ordinary posed by a chemically active body, we can, in most cases, predict the nature and the properties of the new products formed by its action. If the active chemical agent be an acid, all, or a part of, the ele- ments of the organic body combine to form a base, or to form water ; if it be a base, they unite to form an acid, that is, a compound, the properties of which 8 METHODS OF INVESTIGATION are opposed to those of the acting body, and by which, therefore, its affinity is neutralised. In the processes* called fermentation and putrefaction, the mode of arrangement of the elements of organic compounds is of a totally different kind ; because here it is not a foreign chemical attraction, but an- other cause, which determines the new arrangement. Now we know, with absolute certainty, that the The trans- products which may be generated from fermentes- formation caused by a cible substances vary, as the state of the ferment or ferment va- ries with exciter varies. 1 he same caserne, the same mem- the fer- brane, which determine the transposition of the ele- ments of sugar so as to form lactic acid, cause, in another state, the same elements to divide them- selves into carbonic acid and alcohol, or into butyric acid, carbonic acid, and hydrogen gas. These prin- No one can fail to perceive the significance of ciples are concerned these facts, in respect to the understanding and the in the vital processes, explanation of many of the vital processes. If a change in the position and arrangement of the ele- mentary molecules of animal compounds can exert, out of the body, a decided influence on a number of organic substances, when brought in contact with them ; if these substances are thus decomposed, and new compounds formed of their elements ; and if we consider, that among these compounds, namely, such as are susceptible of fermentation, are included all those matters which constitute the food of man and of animals, it cannot be doubted, that the same cause plays a most important part in the vital pro- IN ANIMAL CHEMISTRY. 9 cess ; that it has a great share in the alterations which nutritious matters suffer when they are con- verted into fat, into blood, or into the constituents of organised tissues. We kftow, indeed, that in all parts of the living animal body a change takes place ; that portions of living tissues are separated ; that their constituents, Fibrine, Albumen, Gelatine, or whatever they may be called, give rise to new compounds ; that their elements combine to form new products ; and in the present state of our know- ledge we must suppose that, by means of this very action, at all points where it occurs, according to its direction and force, a parallel, or corresponding, change is effected in the nature and composition of all the constituents of the blood or of the food which come into contact with them ; and that, con- The change . f matter is sequently, the change or matter is itself a chief a chief cause of the transformations which the constituents transform- of the food undergo, and also a condition of the thefood. process of nutrition. We must further admit, that with every modification produced by a cause of dis- ease in the process of transformation of an organ, of a gland, or of one of their constituents, the action of this organ on the blood conveyed to it, or on the nature of .the resulting secretion, must, in like man- The change ner, be changed; that the effect of a number of influenced remedies depends on the share which they take in andbyTe 38 the change of matter ; and that such remedies exert an influence on the quality of the blood or of the food, chiefly in this way, that they alter the direc- 10 METHODS OF INVESTIGATION tion and force of the action taking place in the organ, which action they may accelerate, retard, or arrest. Relation of The intermediate members of the almost infinite se- acid,'&c. to ries of compounds which must connect Urea and Uric very littk acid with the constituents of the food, are, with the exception of a few products derived from the bile, almost entirely unknown to us ; and yet each indi- vidual member of this series, considered by itself, inasmuch as it subserves certain vital purposes, must be of the utmost importance in regard to the expla- nation of the vital processes, or of the action of remedies. - The chief constituent of bile is a crystal- lisable compound ; and no physiologist now denies, that it is indispensable for the process of digestion. Thear- Were we to discover in the organism certain founcTin 11 8 arrangements by which a permanent electrical cur- Lust have rent must be determined at all points, could any one the^taT t0 doubt that such a current must take a share in the processes. v j^ p rocesses ? Q r if ft we re proved, that from the constituents of the food of all animals, among other compounds, organic bases are formed, which in their chemical nature resemble caffeine or qui- nine, or any other organic base ; if such compounds could be detected everywhere, in all parts, or only in certain parts, of the organism, should we not have advanced a step nearer to the explanation of the action of caffeine or of quinine ? About ten years since, the ultimate analysis of organic bodies furnished physiology with a result IN ANIMAL CHEMISTRY. 11 highly important, in order to the easy understand- Erroneous ,,-..,. .... T , deductions ing of the digestive or nutritive process, by demon- from the strating, that fibrine, albumen, and caseine have the idffiy in same composition. Misled by this result, many che- mists thought that the chief problem to be solved bumen, and by chemistry was to ascertain, by ultimate analysis, c the composition, in 100 parts, of all the constituents of the body; and thus many were induced to act on each of these constituents, without a more mi- nute study of its chemical relations and its proper- ties, with alcohol, ether, and acids ; and with the aid of the known resources of organic analysis, to determine the percentage of carbon, nitrogen, hy- drogen, and oxygen. They believed that they had thus, by means of these numerical results, done a real service to physiology, although the only addi- tion thus made to the natne of the substance ana- lysed was an empty formula, of the accuracy of which there was no evidence whatever. Now that NO P ro- . gress has we have been for ten years in possession of these been made ., , by the aid formulae, every one must perceive that we have of mere made no real progress. The cause of this is obvious to all who know the true value of ultimate analysis. Ultimate analysis is a means of acquiring know- ledge, but is not itself that knowledge. Even sup- posing, what no one will seriously maintain with regard to the constituents of the animal body, that analysis had made us acquainted with the exact pro- portions in which their elements are united toge- ther, yet this knowledge gives us not the least in- 12 METHODS OF INVESTIGATION The mode of arrange- ment of the elements is the essen- tial point. Ultimate analysis is not suffi- cient. It must be accom- panied by the study of products of decomposi- tion. formation as to the arrangement of these elements, or the way in which they group themselves, under the influence of chemical agencies. Now it is the knowledge of both these things together which alone can lead us to definite views as to the part which these compounds play in the vital processes, or the changes to which they are subjected up to the pe- riod of their expulsion from the body ; and this is essentially the problem which Chemistry has to solve in reference to the vital process. Ultimate analysis, by itself, has this peculiarity, that in the case of very complex substances it can- not secure the chemist against errors, because there is no other control for the accuracy of the analysis than the analysis itself; and because the errors are equal at different times, and escape notice when we cannot change the methods of determining the indi- vidual elements. Now there is as yet no means of determining the weight of carbon otherwise than in the form of carbonic acid, or that of hydrogen other- wise than in the form of water. The only way to attain an accurate expression for the composition of those substances, which, like the constituents of the animal body, contain a very large number of elementary molecules in the complex atom of the compound, is to endeavour to resolve it into two or more less complex compounds, and to compare the composition and the amount of these products with those of the body from which they have been derived. IN ANIMAL CHEMISTRY. 13 In this respect, the history of Salicine offers the Example from the most striking instance, and may serve to convince history of every one how little can be attained in questions of ^ this kind by means of ultimate analysis alone. Five of the most accurate and conscientious chemists endeavoured, with all the dexterity which they are known to possess, to fix the relative proportion of the elements in salicine (a body of a far less com- plex nature than animal substances), but without the slightest success, until a method, discovered by Piria, of resolving salicine into two other com- pounds, at once, and without further exertion, re- moved the difficulty. For each compound there is but one correct formula, but there are innumerable formulae which approach the truth ; and it can only occur by the rarest chance that a chemist succeeds in discovering the true formula of a compound from the results of its ultimate analysis. But the con- fidence which we repose in the dexterity of a che- mist can never furnish a foundation for theoretical views ; and it has not yet been the lot of any analyst to stand free from error in this respect. Those chemists who have enriched the science with the greatest number of true formulae, have only attain- ed this success by means of their own erroneous formulae. The method just pointed out for attaining an ac- Erroneous curate formula has not, however, escaped the notice of those who regard ultimate analysis as the last and highest object of a chemical investigation ; but 14 METHODS OF INVESTIGATION the utterly fallacious application of this method has misled them into far greater errors and inaccuracies. Fallacious They believed, for example, in studying a sub- stance, that they had fulfilled all the requisite con- ditions when they had succeeded in representing its decomposition in the form of an equation, with- out caring whether the formulae which made up the equation represented actual substances, or existed merely in their imagination. The following example will serve to place in a clear light what is here intended. illustration When we dissolve uric acid in diluted nitric acid, from the , . . , , action of carbonic acid and nitrogen gases are given off in equal volumes, and we obtain an acid solution, which, if neutralised by baryta, leaves, on evapora- tion, a mass soluble in alcohol, with the exception of the nitrate of baryta. The products of the de- composition of uric acid by nitric acid, are, there- fore, carbonic acid, nitrogen, and the above-men- tioned residue soluble in alcohol. Now it is evident, that if we ascertain the weight of the uric acid and that of the residue, the composition of the latter, and the proportions by weight of the carbonic acid and nitrogen disengaged, the decomposition may now be expressed in a perfectly correct equation, on one side of which we have the formulae of a certain quantity of nitric acid and water, and on the other, the formulae of the product, soluble in alcohol, of carbonic acid, and of nitrogen. We should thus have performed a series of laborious analytical ope- IN ANIMAL CHEMISTRY. 15 rations, but no investigation of the slightest scien- tific value ; for every one knows that the product soluble in alcohol consists of at least five different substances, the relative quantity of which varies with the temperature and the concentration of the acid. If we had mixed the solution of this product with a salt of lead, we should have obtained one precipi- tate ; with subacetate of lead, a second ; and by subsequently adding ammonia, a third ; which, after we had ascertained their composition, would have enabled us to insert in the equation, instead of the formula of the original product, two or three new formulae. The equation would still have continued accurate, but it would have contained merely ima- ginary values, and not the formulae of real sub- stances, existing independently of the numbers. If we compare with this example the investiga- Example tion of the products which albumen, fibrine, and proteme caseine yield, when acted on by strong alkalies, we pounds. shall immediately perceive, that the equations em- ployed in books and treatises to represent the changes which occur, as well as the formulae of the products assumed in these equations, have been obtained entirely by this fallacious method, and that these statements are utterly worthless for our purpose. Mulder, in his " Versuch einer physiologische Mulder's Chemie," Part IV. p. 321, says : " When white of equ& egg, or any other proteine compound, is boiled with potash, entire decomposition takes place. The pro- 16 METHODS OF INVESTIGATION represent- ducts of this reaction are certainly not derived from ing the de- cpmposi- the proteine alone, but still some of them must be tion of pro- teine by regarded as constituents of that substance. These alkalies, are: c. H. N. O. 2 eq. Leucine 24 48 4 8 2 Protide* 26 36 4 8 2 Erythroprotide 26 32 4 10 4 Ammonia 24 8 2 Carbonic Acid 2 4 1 , Formic Acid .. 22 3 2 eq. Proteine + 9 eq. water = 80 142 20 33 " A glance at this equation is sufficient to show, that the agreement is as complete as possible. On one side we have the elements of proteine and of water, on the other, six products of decomposition ; the sum of the elements being exactly equal on both sides ; and yet a repetition of the experiment on which the equation is founded, teaches us that the is quite whole explanation is utterly fallacious. For the fallacious. chief product of this decomposition is a compound (possibly more than one compound) not precipitable by salts of lead ; there is produced no formic acid, but oxalic acid, as well as valerianic and butyric acids ; and in the case of fibrine, caseine, and the albumen of the serum of blood, there is formed a crystallisable body, Tyrosine (I give this name* to * Erythroprotide is that product which is precipitated by neu- tral acetate of lead ; protide that which is thrown down by sub- acetate of lead. IN ANIMAL CHEMISTRY. 17 the substance described by me in the " Annalen der Chemie und Pharmacie," vol. Ivii. p. 127), in all, therefore, five members, which are wanting in the equation. Moreover, according to the above equa- tion, 100 parts of white of egg should yield 30 parts of leucine, whereas, in reality, we can obtain hardly 2 per cent, of that compound. Such explanations as the above are founded on an imperfect notions of imperfect conception of the true object of a chemi- the true . . province of cal investigation ; and when the same author, in chemical order to support his view, that the iron in the co- louring matter of the blood exists in that compound as metallic iron (which amounts to the same thing as saying, for example, that sugar contains carbon in the form of diamond), asserts, that by leaving the red matter of the blood in contact with oil of vitriol, and then adding water, he obtained hydrogen gas ; or when he states, in order to have a source, peculiar to himself, of the nitrogen in plants, that, according to his experiments, certain constituents of peat and brown coal possess the property of condensing the nitrogen of the air, and converting it into ammonia, or some similar compound of nitrogen, these state- ments are so many irrefragable proofs that he enter- tains erroneous views as to the true object of scien- tific researches. Without possessing the gift of pro- phecy, we may safely predict that we shall have, in a few years, in place of the formulae which he has given for animal compounds, and which he regards as for ever established, entirely different formulae. c 18 METHODS OF INVESTIGATION It will fare with these analyses as with those which he has made of vegetable mucilage, of pectine, of glycocoll (sugar of gelatine), and other substances, for the accuracy of which the dexterity of the che- mist is for a time regarded as a guarantee, but which cease to be considered accurate, when the sub- stances analysed become the subject of more exact investigation. Erroneous When such fallacious principles and methods of theories im- ..... . -, , ,1 pedepro- investigation are accompanied by erroneous theo- retical views, which, while they refuse admission to the most convincing evidence of the truth, are de- fended with a violence and obstinacy proportioned to the feebleness of these views, the field of research becomes a stage on which the most selfish passions are brought into action ; but, under such circum- stances, progress is out of the question. A theoreti- A theoretical view in natural science is never only true absolutely true, it is only true for the period during riod. e which it prevails ; it is the nearest and most exact expression of the knowledge and the observations of that period. In proportion as our knowledge is extended and changed, this expression of it is also extended and changed, and it ceases to be true for a later period, inasmuch as a number of newly acquired facts can no longer be included in it. But the case is very different with the so-called proteine The theory theory, wliich cannot be regarded as one of the of proteine never ex- theoretical views just mentioned, since, being sup- pressed the knowledge ported by observations both erroneous in themselves IN ANIMAL CHEMISTRY. 19 and misinterpreted as to their significance, it had no of a given foundation in itself, and was never regarded, by those intimately acquainted with its chemical ground- work, as an expression of the knowledge of a given period. In the " Annalen der Chemie und Pharmacie " Defects of (vol. Iviii. pp. 129 et seq.), Laskowski has already fully developed the analytical evidence which bears against this theory, and we may here direct atten- tion to the defects of the theoretical notions on which it rests, or, more properly, does not rest. The results of the ultimate analysis of fibrine, Supposed albumen, and caseine attracted, ten years ago, the composi- attention due to them ; since they seemed to prove brine, aibu that these three bodies had the same composition, the notions entertained concerning the process of digestion and nutrition acquired a great degree of simplicity ; these results contributed to demonstrate the value of chemical composition as an element in the discussion of physiological questions. But this result, derived from ultimate analysis, had two disadvantages. The first was, that we were disposed to believe that identity of composition in the sulphurised and nitrogenised constituents of food and those of the blood was indispensable for the un- derstanding and explanation of the digestive pro- cess. But, theoretically, this identity of composi- tion is not indispensable ; it only facilitated the tritive pro~- investigation. When a chemical attraction causes c the formation of a compound, it is, in regard to the c2 20 m METHODS OF INVESTIGATION chemically active, or attracting, body, quite indiffe- rent whether the atoms which it attracts form a group, bound together by their mutual attractions, or are simply arranged near each other, without being combined. To produce the compound, it is only necessary that the attractive force should be more powerful than the forces which oppose its manifes- tation, that is, the formation of the new compound. If the attractive force preponderates, the attracted elements enter into the new combination, and this, whether they have been previously arranged in one, two, or three compound molecules or groups ; and the result is exactly the same as if the attracting body had combined with one group of combined atoms. Example. Hydrocyanic acid, for example, mixes in every proportion with water, just as many liquids do, which may be mixed without forming a chemical combi- nation ; but when the atoms of water and of hydro- cyanic acid are in a certain degree of proximity, and we add hydrochloric acid to the mixture, the mixture acts as if it were a compound of ammonia with formic acid. The hydrochloric acid is con- verted into sal ammoniac, while the remaining ele- ments unite to produce formic acid. Here the nitrogen of the hydrocyanic acid and the hydrogen of the water, two elements, belonging to two en- tirely distinct compounds, act, in reference to the hydrochloric acid, as if they were combined to form the compound atom which we call ammonia. * INT ANIMAL CHEMISTRY. 21 In like manner, the formation of the blood con- stituents would have equally admitted of explana- tion, and would have been equally well explained, even had the food contained, instead of one sulphur- ised and nitrogenised constituent, two or three com- pounds, in one of which was found the sulphur, in the second the nitrogen, and in the third the carbon required to make up the sum of the elements. Under the influence of this idea of the necessity Fibrine dif- P.,.., , ., .. / i f ers i n com- or identity in the chemical composition of the con- position stituents of the blood and those of the food, Mulder me^and"" was first led to assume, in fibrine, the same relative c proportion of atoms of nitrogen and carbon as in albumen and caseiiie, in spite of the analyses of Gay Lussac and Thenard, of Michaelis, of Vogel, and of Fellenberg, all of which indicated a larger propor- tion of nitrogen in fibrine; and his example, or rather, the influence of his authority, reacted on several of those who followed him, who were so far misled as to reject as inaccurate the greater number of their own accurate analyses, and to give the pre- ference to those which were defective. The second, and far more serious disadvantage, Erroneous , i . (. . , , , . . . . . views de- Was the erroneous view or the chemical constitution duced from of the three animal substances just named, which chemists believed themselves justified in deducing tlty * from the identity of their composition in 100 parts. The question, in what way the elements of fibrine, HOW are albumen, and caseine are arranged, is one of the menu of 22 METHODS OF INVESTIGATION these com- most interesting and important in Animal Chemis- pounds ar- ranged? try. These three bodies contained (at that time this was still believed in the case of fibrine) an equal amount of carbon, nitrogen, hydrogen, and oxygen, while there was great difference in their physical properties. But we had been long familiar with groups of compounds, which, with a perfect . identity of composition, exhibit the most marked differences in their properties ; this supposed iden- tity of composition was not, therefore, surprising. In all isomeric substances, more exact research had demonstrated, that their elements were differently arranged, and that, consequently, their chemical constitution was to the full as different as were their physical properties. Although their composition in 100 parts was the same, yet their atomic weight, or the products of their decomposition, or their density in the state of vapour, was different ; the variation in their chemical constitution corresponded to that of their physical properties. Butisomer- What, now, according to these previous observa- ism was not f supposed to tions, was the cause of the great dissimilarity in furnish the explanation the properties of the above-mentioned animal sub- stances ? If their elements were differently ar- ranged, or the products of their decomposition or transformation different, this formed, of course, no obstacle to the probable conversion of one into the other, of caseine or fibrine into albumen, or of albu- men into caseine and fibrine, since the study of isomeric substances had taught us, that in many IN ANIMAL CHEMISTRY. 23 cases, even where the difference of chemical consti- tution was very great, such transformations of one into another actually occur. All this was left unex- plored. The chemist who first entered in this field AH these substances of research, which promised so abundant a harvest, were sup- assumed, on the strength of the most defective ex- contain a periments, that in these three substances the four above-named elements were combined, exactly in the same way in all, to form a group, which group constituted a distinct substance, capable of being isolated, to which the name of proteins was given, called pro- Assuming the chemical constitution of this group as the same in all three bodies, what was now the origin of so great a difference in properties as they presented ? The cause of this difference was sought for in a fifth element, or in a second group. It was found, namely, that all these animal sub- combined f. 7 7 ., with various stances contain a certain amount of sulphur ; it was proportions assumed, that some of them contained also a certain and pLt- amount of phosphorus ; and the variation in their p properties was ascribed to the presence of this sul- phur, or sulphur and phosphorus. (The existence although of phosphorus, as an essential element of these sub- no 7shown , , -, . to contain stances, has not, however, been in any way esta- blished.) In this way an organic radical, or a body analogous to organic radicals, was created ; a body formed by the combination of twelve hundred ele- mentary atoms, a group of twelve hundred atoms, the physical character of which was determined by the addition of one or more atoms of sulphur, or of 24 METHODS OF INVESTIGATION sulphur and phosphorus. To support this view, a property .was imagined, which a compound of sul- phur could not possibly exhibit. The sulphur, which in these compounds caused such striking dif- ferences, was as loosely combined with the proteine, as we find it in a mixture of iron filings or sawdust with sulphur. It was supposed, that when these substances are acted on by an alkali, the sulphur was detached from the proteine, just as easily as if it had not been combined with it; it dissolved in the form of sulphuret of potassium and hyposulphite of potash ; the proteine was thus set free, and dis- solved also in the excess of alkali ; and when this f/ Zr alkaline liquid was neutralised by an acid, the fun- damental constituent of these animal substances, the proteine, was obtained in the form of a gelatinous Supposed precipitate. The idea of the sulphuret, or of the proteine, sulpho-phosphuret, of proteine, led at once to a series of oxides of proteine, to a multitude of ima- ginary substances, to which was now ascribed, as of old to phlogiston in chemical processes, the function of determining and effecting all the changes which occur in the vital process. Let us now see to what truths this supposition has led, and how it explains the differences in the properties of the animal substances. In the latest work of Mulder above quoted (p. 316), the consti- Composi- tution of the proteine compounds is represented as tion of ani- _ ., mal sub- lOllOWS : IN ANIMAL CHEMISTRY. Zi) Crystalline humour contains for 15 eq. Proteine 1 eq. Sulphur stances ac- Caseine ,,10 1 , cording to Vegetable gelatine ,, 10 Albumen of eggs ,, 10 Fibrine ,, 10 Albumen of blood ,, 10 2 Mulder. & 1 eq. Phosphorus 1 1 We have now reached the ultimate object of this theory; and the question, What insight has it af- forded ? is answered by a glance at the above table. The albumen of the blood, the properties of which Albumen of coincide so closely with those of the albumen of to differ eggs, chemically as well as physically, contains twice me of U as much sulphur. Here, similarity of properties eggs> accompanies a difference in composition ; and from this we can draw no other conclusion than this, that the sulphur, the amount of which varies, has no influence on these properties. But what is the cause of the great difference while fi. brine has between the properties of fibrine and those of the the same albumen of eggs ? Is it sulphur or phosphorus ? No. tion as ai- These substances contain (according to Mulder) the eggs? ' same quantities ofproteine, sulphur, and phosphorus. Such is the progress which Animal Chemistry has Such views . . constitute made in eleven years in regard to the chemical no real pro- constitution of the blood constituents ; we know as 8 much of it now, as we did forty years since ; not to mention that the assumption of the presence of phosphorus in albumen and fibrine, an assumption resting on the most frivolous experiments, renders the explanation of the transformation of the caseine of milk into blood utterly impossible. Any one who will take the trouble to prepare Sulphur exists in 26 METHODS OF INVESTIGATION two forms the so-called proteine according to the directions of in animal substances; Mulder, must immediately perceive that sulphur is contained in fibrine, albumen, and caseine in two distinct forms of combination. in the form If we suppose these bodies to consist of several groups of atoms, of which groups two contain sul- phur, the action of alkalies on them points out that the sulphur in one of these compounds exhibits the same relations as the sulphur in cystine ; the sul- phur of this compound combines with potassium, while it is replaced by the oxygen of the potash ; but the other compound of sulphur remains un- andintau- changed, and its sulphur exhibits the relations of rine. that contained in taurine. We observe, moreover, that the former (the more easily decomposed) of these sulphur compounds preponderates in the albu- men of the blood ; the latter in caseine. Any one who reads the note which I published thirteen months ago in the " Annalen der Chemie und Pharmacie " (vol. Ivii. p. 133), on these ques- tions, will admit, that it was impossible to use greater forbearance in pointing out to the author of the proteine theory the error into which he had fallen than I then did, while I afforded him the oppor- tunity of repeating his experiments. The result, however, was the publication of his recent pam- phlet, a work which I shall not further notice, pre- ferring to leave the facts, as now ascertained and generally admitted, to speak for themselves. Results of It now appears, as the result of the more accurate recent re- IN ANIMAL CHEMISTRY. 27 investigations of Laskowski, Ruling, Verdeil, Wai- searches. Larger ther, and Fleitmann, that the amount of sulphur amount of sulphur present in the blood constituents is three times, in present. many cases four times, as great as the apparently well established analyses of the author of the pro- teine theory had indicated. It further appears, that Proteine cannot be a body, destitute of sulphur, and having the compo- obtained by sition of proteine, is not obtained by the methods methods. given by Mulder ; that fibrine differs in composition from albumen ; that the albumen of eggs contains not less, but more sulphur than the albumen of the blood, which sufficiently explains the disengagement of sulphuretted hydrogen in the experiments made with the former on artificial digestion. The study Products of the decom- of the products, which caseine yields when acted on position of by concentrated hydrochloric acid, of which, as Bopp latine, and has found, Tyrosine and Leucine constitute the constu chief part, and the accurate determination of the products which the blood constituents, caseine, and gelatine, yield when oxidised, among which the most remarkable are oil of bitter almonds, butyric acid, aldehyde, butyric aldehyde, valerianic acid, valeronitrile, and valeracetonitrile, have opened up a new and fertile field of research into, numberless relations of the food to the digestive process, and into the action of remedies in morbid conditions ; discoveries of the most wonderful kind, which no one could have even imagined a few years ago ; and the investigation which I now proceed to describe, will, I trust, contribute to excite the hopes of che- 28 ACID REACTION OF mists and of physiologists, and encourage them to direct their efforts, more than they have hitherto done, towards this department of science. Acid reac- tion of the juices of SECTION II. On the Constituents of the Juices of Flesh. It has lonsf been known that the flesh of newly- killed animals reddens blue litmus paper, while nothing certain is known as to the nature of the free acid which causes this reddening. Berzelius, in his detailed investigation of the juice of flesh, observes on this subject as follows :* When the liquid " (obtained by pressure from the muscular substance) " out of which the albumen " and the colouring matter have been coagulated, " is evaporated after filtration, it leaves a yellowish " brown extract, of which alcohol takes up the half or " more with a yellow colour. After the evaporation " of this solution there is left an extract-like mass, " mixed with crystals of common salt, which has a " strong acid reaction, and notwithstanding leaves " on incineration an ash containing an alkaline car- " bonate, thus proving that the mass contained an " organic acid, partly free, partly combined with " alkali. If the alcoholic solution be mixed with a " solution of tartaric acid in alcohol, potash, soda, " and lime are deposited in the form of tartrates, and * Handbuch, vol. ix. p. 573. THE JUICES OF FLESH. 29 " there remains in the alcoholic solution, along with " tartaric and hydrochloric acids, a combustible acid " dissolved. The solution is digested with finely- " divided carbonate of lead, till lead is detected in " the liquid ; it is then evaporated, the lead preci- " pitated by sulphuretted hydrogen, the acid liquid " boiled with animal charcoal and evaporated. It " leaves a colourless, very acid syrup, possessing all " the characters of lactic acid, but still retaining a " portion of extractive matter mixed with it." This is essentially the amount of all that is known in regard to the nature of the free acid present in the muscles. In his researches on urine and on milk, Berze- lius, by employing a similar process, obtained also strongly acid extractive substances, the properties and chemical relations of which he explained by the presence of lactic acid. Whether these statements can at the present time is lactic acid pre- be regarded as proofs of the existence of lactic acid, sent? that is, of the acid now called by that name, will be best seen from the opinions which Berzelius enter- tained concerning the nature of lactic acid, both at the time when his researches were made (1807), and subsequently (1823 and 1828). On the occasion of his report on Daniell's lampic Earlier and later views acid, Berzelius observes,* ;; These researches render of Berzelius " it very probable that the lactic acid, which occurs nature of ,. IT. T -i i i T " so frequently in the animal kingdom, and which I * Jahresbericht, Jahrgang ii. p. 72. 30 LACTIC ACID, TILL LATELY, " have endeavoured to prove in a former work to " be different from acetic acid, is likewise nothing in 1807, " more than a similar combination of acetic acid 1823, " with a peculiar animal substance, which accompa- " nies it in its salts, is the cause of the differ- " ences between these salts and the acetates, and " moreover prevents the volatilisation of the acid, " as long as the foreign matter is not destroyed. " A further inducement to adopt this opinion is " derived from the circumstance, that concentrated " lactic acid, when neutralised with caustic ammonia " and heated, yields distinctly vapours of acetate of " ammonia, becoming acid at the same time." 1828, In the seventh yearly volume of his Jahresbe- richt, Berzelius again observes, in considering Tie- demann and Gmelin's important researches on digestion, on the occasion of their mentioning acetate of potash as an ingredient of saliva (p. 200), " They " (Tiedemann and Gmelin) " assume, on the " authority of Fourcroy and Vauquelin, as well as of " their own experiments, and, as they say, of mine " also, that lactic acid is only acetic acid, rendered im- " pure by the presence of an animal matter. I have " certainly made experiments with the purpose of " resolving lactic acid into acetic acid and a foreign " substance ; but I am not aware that I have ever " succeeded in doing so ; and as long as we cannot " obtain acetic acid from it without destructive " distillation, or as long as lactic acid cannot be " formed from acetic acid and an animal substance, VERY IMPERFECTLY KNOWN. 31 " so long it is best to retain the name of lactic acid ; " for if lactic acid be a chemical compound of acetic " acid with an animal substance, which enters into " the composition of the salts, and deprives the acetic " acid of its volatility, it would be as inaccurate to " call these salts acetates, as to call the sulphovi- " nates or nitroleucates sulphates or nitrates." In his last investigation on this subject,* Berze- and 1832. lius describes some experiments, from which it might be concluded that lactic acid contains no acetic acid, and he terminates his researches with the following words : " Future investigations must be chiefly " directed to ascertain, whether that which has been " called lactic acid be a mixture of two acids, which " resemble each other, but yet yield different salts." From these passages it is evident, that, at the The true time when chemists began to reckon lactic acid lactic acid among the ingredients of the fluid of the muscles, taUecToT" the properties of the acid now known by that name were almost entirely unknown : so much so that the acid discovered by Braconnot, which is formed in rice-water and in the juice of beet-root, was consi- dered as a peculiar acid, till L. Gmelin proved it to be identical with the acid of sour milk, and C. Mitscherlich described his method of obtaining lactic acid from sour milk in a state of purity. It is plain that the assumption of the existence of The former evidence of lactic acid in the animal body, founded, forty years the pre - senceoflac- ago, on grounds so uncertain and variable, could no tic acid in the body is * Annalen der Pharmacie, vol. i. p. 1. 1832. 32 THE ACID OF THE GASTRIC JUICE. no longer longer be admitted in our day, more particularly as no chemist, after Berzelius, has occupied himself with a more exact study of the subject, or has attempted to prove that the acid of the muscles is identical with that of sour milk. This identity, or indeed the presence of a non-nitrogenised organic acid as an ingredient of the living body, was ren- dered still more doubtful and improbable, when the especially accurate investigation of urine, in which lactic as it has been shown acid was said to be present, had proved the absence not to exist . . in urine. OI it in that fluid. What is the I regarded the determination of the nature of acid of the gastric the acid diffused through the chief mass of the body, as the more important, that this alone could give us an explanation of the nature and origin of the acid which takes a share in the digestive pro- cess. The acid of the gastric juice is not formed during digestion from the ingredients of the food, which in themselves are not acid, but is secreted from the lining membrane of the stomach even in the fasting state. If this acid were an ingredient of the blood, then it must admit of being detected in the blood or in some other part of the body. Supposed Several French chemists, resting their conclusions on qualitative researches, have indeed stated that to be the acid of the gastric juice is lactic acid ; but the lactic acid. reac ^j ons? wn i cn were held to prove the presence of lactic acid, either do not belong to that acid,* or are such as lactic acid possesses in common with * See Annalen der Chemie und Pharmacie, vol. Ixi. p. 216. KREATINE DISCOVERED. 33 other acids, particularly with phosphoric acid, which is never absent in animal fluids. In 1835, Chevreul described, as an ingredient of Kreatine discovered the liquid obtained by boiling flesh with water, a by chev- new substance, under the name of Kreatine (from , flesh), which was distinguished by its proper- ties from all known compounds. He obtained it in very small quantity by acting with alcohol on the residue obtained by evaporating the soup in vacuo. The properties of kreatine, as observed by this His account of its pro- distinguished chemist, are as follows : " Kreatine is " distinguished by the transparency of its crystals, " which are right-angled prisms of mother-of-pearl " lustre ; it is heavier than nitric acid of sp. g. 1*34 " and lighter than sulphuric acid of sp. g. 1*84. It " has no action on vegetable colours ; its solution in " water is not precipitated by chloride of barium, " by oxalate of ammonia, nitrate of silver, sulphate " of copper, protosulphate of iron, subacetate of " lead, or bichloride of platinum. 1,000 parts of " water at 15 C. (64 F.) dissolve 12-04 parts of " kreatine ; alcohol of sp. g. 0*804 dissolves about of its weight. Its solution in nitric acid, " when warmed, gives off nitrous acid, and leaves " on evaporation a residue, which gives a precipitate " with chloride of platinum, and deposits small " granular crystals. Kreatine dissolves in hydro- " chloric acid : the solution gives on evaporation " colourless dendritic crystals, which do not precipi- " tate bichloride of platinum. D 34 PROPERTIES OF KREATINE. " In its aqueous solution, kreatine is sponta- " neously although slowly decomposed, there is " observed a distinct odour of ammonia along " with a heavy, mawkish smell ; the liquid loses its " transparency. " When heated in a small tube, kreatine decrepi- " tates, gives off water, becomes opaque and dull, " then melts without becoming coloured, and is finally " decomposed, ammonia being disengaged, along " with a smell of hydrocyanic acid and phosphorus. " There is condensed in the upper part of the tube " a yellow vapour, partly in the liquid state, partly " in the form of crystals. The carbonaceous residue " is trifling, and leaves on incineration a mere trace " of ashes, which contain no chloride of sodium. " Kreatine contains water of crystallisation, which " is expelled by a heat of 212 ; its ultimate ele- " ments are carbon, hydrogen, nitrogen, and oxygen, " in proportions not yet ascertained." (Journal de Pharmacie, vol. xxi. p. 236.) Opinion of Chevreul compares this substance with asparagine, t?ft7na- as and shows that it cannot be confounded with that ture * substance. He adds that kreatine, when acted on by baryta, yields an acid very different from aspartic acid. " Perhaps," he says, " it is an ammoniacal " salt, formed by the combination of ammonia with " an organic acid." Berzeiius After Chevreul had published his observations on to Suit 8 , the occurrence of kreatine, several chemists endea- voured again to obtain this substance. Berzeiius ATTEMPTS TO OBTAIN IT. 35 observes on this subject, in his " Handbuch," that " After the discovery of Chevreul became known, I " tried in vain to prepare this substance from " raw beef. Meantime I have had an opportunity His op u " of seeing kreatine in the possession of that dis- n " tinguished chemist. It would appear, there- " fore, rather to be an accidental ingredient, the " presence of which depends on peculiar circum- " stances in the feeding of the cattle, and which " therefore is sometimes present and at other times " absent. If, accordingly, it should be found in the " liquid in which beef has been boiled, it would " evidently be the product of a metamorphosis." Wb'hler observes, in a note on this passage, " I have Wohier ob- " obtained this substance from the soup of 8 Ibs. of is not aiian- " beef, in yellowish crystals. It is not allantoine, " as I suspected it might be." Schlossberger, in his examination of the muscles Schiossber- of the alligator,* says, " The aqueous extract of the m the flesh " flesh, heated to coagulate the albumen, filtered, gator. " and evaporated in the water-bath, yielded a " brownish-yellow syrup, pretty strongly acid, with " an odour of roast meat, such as is understood " under the term Osmazome, as obtained from ordi- " nary flesh. Hot alcohol dissolved a considerable " part with a yellow colour, and deposited on cool- " ing small cubical yellowish crystals, which may be " washed with water, or better with alcohol. Thus " purified, they had all the characters of Chevreul's * Annalen der Chemie und Pharmacie, vol. xlix. p. 343. D2 36 SCHLOSSBERGER'S EXPERIMENTS. " kreatine. When heated, they become white and " opaque, then melt, giving out a yellow vapour and " an ammoniacal empyreumatic odour, leaving a " coal, which, after long ignition, leaves a mere " trace of ashes. Heated with nitric acid on the " platinum spatula, they caused, for an instant, on " the addition of ammonia, a rich yellow colour, soon " passing into brown. They dissolved in strong " nitric acid with the evolution of yellow vapours, " and the solution, when evaporated, left a white " residue. The aqueous solution of the crystals is " not precipitated by nitrate of silver, subacetate of " lead, or salts of baryta. Unfortunately the quan- " tity in my possession was not sufficient for an " elementary analysis, since from several pounds of " flesh I only obtained 0'15 gramme (2*3 grains). " At all events," continues Dr. Schlossberger, " it " is desirable to recommence the search for this " singular substance, which Chevreul discovered in " the soup of the Dutch Company, but which Ber- " zelius and Simon could not obtain. I myself was ' " also unable to detect it in my numerous analyses of " flesh in 1838, although I expressly sought for it. " Wohler has obtained a small quantity from ox flesh, " and has determined that it is not allantoine. It Schiossber- " would appear therefore either not usually to occur nion. P " in the substance of the muscles, or to occur in so " small a quantity that it cannot be detected. How- " ever this may be, the detection of this substance, so " well characterized by its tendency to crystallise KREATINE IN THE JUICE OF FLESH. 37 " and its whole chemical character, in the flesh of " animals so widely separated as the ox and the " crocodile, must be regarded as a fact worthy of " attention." This is the essential part of all that is known from Results of previous researches in regard to lactic acid and researches kreatine as ingredients of flesh. With respect to the other substances which are spoken of in chemical works as ingredients of flesh, I believe I need make no further quotations, since their intimate chemical relations are entirely unknown, and they offer no remarkable peculiarities beyond the facts that they are precipitated by acetate and subacetate of lead, by corrosive sublimate, tannic acid, or chloride of tin. In the early part of my investigation I succeeded, The author succeeds in after many fruitless attempts, in obtaining a small obtaining quantity of kreatine from the juice of the flesh of fowls, and the study of its chemical relations soon showed, that this substance, during the evaporation of the fluid, loses its power of crystallising, in conse- quence of a change which it undergoes under the influence of the free acid present in the solution, and that in this way its purification and preparation are rendered much more difficult. The separation of the non-nitrogenised acid, which I soon found to be present in the juice of flesh, was at first attended with no small difficulties, and ultimately it is only the more exact acquaintance with the other sub- andinde- vising sim- stances occurring in this fluid, which has led to the pie methods ,, of obtaining simple methods of preparing and separating them, theconstu 38 METHOD OF EXTRACTING THE tuents of to be described in the following pages in the order in which they present themselves to the observer. Flesh ex- When the finely minced flesh of newly-killed water. animals is extracted by water, there is obtained a red or reddish coloured fluid, having the taste which is peculiar to the blood of different classes of animals. If this fluid be heated in the water-bath, the albumen, as Berzelius has observed, coagulates first, and the liquid retains its red colour. The Albumen albumen at first separates as a nearly colourless ii?g matter coagulum, which afterwards collects in denser floc- by & heat, e culent masses, and the colouring matter is only sepa- rated at a considerably higher temperature. It is easy to observe the point at which the albumen has been entirely coagulated, while the red colouring matter still remains in solution. It is now only necessary to bring the liquid into actual ebullition in a silver or porcelain vessel, in order to separate the whole of the colouring matter in the coagulated state, and we The filtered thus obtain a liquid easily filtered, which reddens S a litmus powerfully. The coagulated albumen, as well as the undissolved fibrine and cellular tissue, have also an acid reaction, which cannot be removed by washing with water. The insoluble residue of the flesh (fibrine, cellular tissue, &c.), when boiled with water, becomes opaque, milk-white, of horny hardness, and the water acquires by dissolving gela- tine the property of gelatinising on cooling, when sufficiently concentrated. A good If we desire to obtain the soluble constituents of CONSTITUENTS OF FLESH. 39 the muscular substance without great loss, and with- press is in- dispensable. out using inconveniently large quantities of water, a good press is indispensable. We can, it is true, by the process I am about to describe, obtain with ease each of the substances mentioned, but to this end it is not advisable to operate on less than from 8 to 10 Ibs. of flesh. It is only necessary to reflect Smaiipro- portion of that flesh contains from 76 to 79 per cent, of water, soluble matter in and from 2 to 3 per cent, of soluble albumen, and flesh. that after extraction with water there are left from 17 to 18 per cent, of fibrine and other insoluble matters, in order to perceive that even when we employ 10 Ibs. and upwards of flesh we are still operating on comparatively small quantities of the soluble constituents. (On the average, the soluble 8 or 10 ibs. matter of 10 Ibs. of flesh, after the coagulation of the should be albumen and colouring matter, does not exceed 4 oz., and of this a very considerable proportion consists of inorganic salts, the phosphates being par- ticularly abundant, while the remainder is formed of not less than five organic compounds.) Supposing that 10 Ibs. of flesh are to be operated Best mode upon, the half of this quantity is taken, and covered tion. with '5 Ibs. of water. The mixture is carefully kneaded with the hands, and is then pressed as completely as possible in a bag of coarse linen. The pressed residue is a second time carefully kneaded with 5 Ibs. of water, and again pressed. The fluid of the first pressing is set aside for further opera- tions, that of the second being, used for the first 40 EXTRACTION OF THE SOLUBLE extraction of the second half of the flesh. In like manner the residue of the first half is a third time treated with 5 Ibs. of water, and the expressed fluid serves for the second extraction of the second half, which is finally extracted a third time with pure water, in which it is allowed to soften, and again pressed out. Coaguia- The united liquids are passed through a clean albumen * cloth to separate any fragments of muscular fibre, ing matter" and then introduced into a large glass globe, which is placed in a pan of water, the latter being gradually heated to the boiling point, and kept at this tem- perature till the liquid has lost its colour, and the whole of the albumen and colouring matter have separated in a coagulum. When a portion, heated to boiling in a test tube, remains clear, and deposits no flocculi, this operation is completed. In many kinds of flesh, it is necessary, in order to separate the last traces of colouring matter after the coagulation of the albumen, to remove the liquid from the globe, and bring it into actual ebullition in a silver or porcelain vessel, which is so much the more easily done that the adhesion of the coagulum to the bottom of the vessel, where it would be singed or burnt, is no longer to be dreaded. It is AH visible moreover advisable, to remove all visible fat as beVemoied. completely as possible from the flesh, or to select the flesh of lean animals, because the fat very much impedes both the extraction of the flesh with water and the pressing of the mass. When fat flesh is CONSTITUENTS OF FLESH. 41 used, the cloths or bags in which it is pressed become quickly useless, their pores being clogged with fat. The liquid, after the coagulation of the albu- characters men and colouring matter, is strained through a qu id filter- cloth, the coagulum pressed, and the united liquids coag$tam: filtered. The colour of the filtered liquid varies with the kind of flesh. That from flesh very full of blood, as is that of the ox, roe-deer, hare, and fox, has a reddish colour ; while that from veal and fowl, as well as that from fish, is hardly coloured. For the preparation of kreatine, the flesh of wild animals and of common fowls is the best adapted. The liquid obtained from these kinds of flesh is, when filtered, clear and limpid ; that of the horse and of fish is always turbid ; the taste of all is nearly the same, and the fluid from the flesh of the fox is in this respect not distinguishable from that derived from lean beef. The fluid from the flesh of the marten possesses a distinct musky smell, which becomes more decided when it is heated and evapo- rated. All the different fluids obtained by the above The liquid . is always process have an acid reaction, which appears to me acid, the more worthy of notice, that, in the case of the ox, sheep, and game, it can only be obtained mixed with a proportionally large quantity of blood ; and yet the alkali contained in the blood, on which its alkaline reaction depends, is yet not sufficient to 42 SEPARATION OF THE FREE ACIDS neutralise the free acid present in the fluid of the flesh. Indeed, I believe that in most animals, if we suppose the whole mass of blood in the vessels to be mixed with the whole fluid of the muscles, and does the mixture would retain, not a neutral or alka- not become neutral line, but an acid reaction. In the hare, the amount when the blood is of whose blood is proportionally small, this is cer- added to it. tainly the case. The acid If the clear liquid, as obtained by filtration, be evaporation concentrated over the open fire, even without being heated to the boiling point, it becomes gradually crystals^ darker in colour, and at last leaves a dark brown syrup, with a smell of roast meat, in which traces of kreatine in crystals only appear after it has stood for a long time. The brown colour is in part caused by the formation of a deposit of dissolved matter, which attaches itself to the bottom of the vessel, and in consequence of the higher temperature to which it is there exposed, passes into a dark soluble substance ; but even when this deposit is avoided, as, for example, when the evaporation is conducted in the water-bath, the dark colour infallibly appears. The acid The chief cause of it, besides the temperature, is the moved presence in the liquid of free acid, which must be removed before evaporation. bytheaddi- To this end there is added to the liquid a concen- tion of ba- ryta. trated aqueous solution of baryta, as long as it pro- duces a white precipitate. After a certain quantity of baryta has been added, the liquid becomes neu- tral or even alkaline, but this must not prevent us IN THE JUICE OF FLESH. 43 from adding it as long as it causes the slightest tur- bidity in a filtered portion of the liquid. The precipitate thus formed consists of phosphate Phosphates are precipi- of baryta, and phosphate of magnesia, and contains tated. none of the double phosphate of ammonia and mag- nesia ; nor is ammonia disengaged by the addition of baryta. In one operation alone, out of many, was NO ammo- a distinct separation of ammonia observed. engaged, The precipitate from the liquid derived from the and no sui- flesh of fowls dissolves in diluted hydrochloric acid found in without residue ; and in those cases in which sul- tate^ 6 phate of baryta remains undissolved, its quantity, compared with that of the flesh, is so trifling, that we may ascribe with perfect certainty the sulphuric acid thus indicated to the mixture of a little blood. After the separation of the precipitate, which The filtered contains the whole phosphoric acid of the fluid of be^entiy flesh, the filtered liquid is divided into flat porce- lain dishes, and concentrated in the water-bath or sand-bath, taking care that it never boils. If the upper edge of the evaporating dish be allowed to become hotter than the liquid, a portion is always dried up on this part, forming a dark brown ring, which, on the addition of fresh liquid, dissolves in it without perceptibly colouring it ; but in this case the colour comes out when the liquid is concentrated. When the liquid from fowls' flesh, after the action of baryta, is evaporated, it continues perfectly clear, only if an excess of baryta has been added, a film of carbonate of baryta forms on the surface. 44 SEPARATION OF KREATINE. In the evaporation of the same fluid from beef, there is formed, when it has acquired a syrupy con- sistence, a mucilaginous skin on the surface, which, when divided in water, swells up without dissolving. A skin In the case of the flesh of the calf and of the horse, some cases these skins or membranes succeed each other con- poratK>n7 a ~ tinually ; they may be removed as coherent mem- branes, and they must be taken away as often as their formation is repeated. The con. When the fluid has been reduced to about ^ of centrated . 11 11 -i i i i liquid de- its original volume, and has acquired a thickish con- posits krea- . , , . tineincrys- sistence, it is placed in a moderately warm situa- tion, and left to evaporate slowly. Very soon small, distinct, short, colourless needles appear on the sur- face, which increase on standing, and on cooling, so that the walls of the vessel are gradually covered with them. These crystals are kreatine. The process thus described applies to all the different kinds of flesh above mentioned, except that of fish, for which a modification of it is re- quired. Modifica- The flesh of fishes, when finely minced, cannot be tionofthe process for pressed ; it swells up with water to a mucilaginous mass, which clogs up the pores of the cloth. We have, therefore, no choice but to mix it with twice as much water as above recommended, to throw the mixture on a funnel, and to displace the fluids by repeated affusion of small quantities of water. The infusion is colourless, slightly opalescent, has an AMOUNT OF KREATINE IN FLESH. 45 acid reaction and a very marked taste and smell of fish. When heated, it yields a perfectly white, soft coagulum, and after the addition of baryta, when evaporated and allowed to cool, yields a colourless jelly, in which, when allowed to rest, very distinct and regular crystals of kreatine form after twenty- four hours. The quantity of kreatine, obtained from different Proportion kinds of flesh, is very unequal. Of all kinds, the i n different flesh of fowl and that of the marten contain the most, then that of the horse, the fox, the roe-deer, the red deer and hare, the ox, pig, calf, and finally that of fishes. The variation in the amount of kreatine is striking it is greater even in animals of the same class. The flesh of S confined a fox, fed on flesh for two hundred days in the ammals - anatomical rooms at Giessen, did not yield so much as the tenth part of the quantity of kreatine obtained from foxes killed in the chase. The amount of kreatine in the muscles of an its amount animal stands in an obvious relation to that of fat, tiontothat or to the causes which determine the deposition of fat. From fat flesh there are often obtained mere traces of kreatine, and always much less than from lean flesh, for the same amount of muscular fibre. The fox above mentioned, which had been fed, yielded more than 1 Ib. of fat from the omentum, while in foxes hunted or shot hardly any fat was visible. From 100 Ibs. (Hessian) of the flesh of an old, Actual N amount of 46 AMOUNT OF KREATINE IN FLESH. kreatine obtained by the author. Kreatine found in all the higher classes of animals. It is not to be lean horse, there were obtained nearly 36 grammes (555 grains) of kreatine. 116 lean fowls yielded about 72 grammes (1,110 grains) ; and 86 Ibs. of beef 30 grammes (463 grains). The weight of the flesh of a fowl was, on an average 203 grammes (3,134 grains, or about 7 oz. avoirdupois) ; that of wild foxes weighed from 2 to 2 j Ibs. (Hessian).* I have found, as already stated, kreatine in the flesh of the ox, sheep, pig, calf, roe-deer, hare, mar- ten, fox, red deer, common fowl, and fish ; and as it cannot be doubted that the crystals obtained by Schlossberger from the flesh of the alligator were also kreatine, it may fairly be concluded that this substance is an ingredient of the muscles of all the higher classes of animals. I have not been able, by the same process, to * Note by the Editor. The figures in the text, when reduced to 1000 parts, indicate that 1000 parts of the flesh of Fowl yielded 3'05 kreatine (crude ?) 1000 the Horse 0'72 1000 the Ox 0-697 In one experiment I obtained from the flesh of eight fowls, weighing hardly 3J Ibs., 78' 75 grains of purified kreatine, or 3' 21 parts from 1000. A second experiment, with the same quantity of flesh, yielded 71 grains of pure kreatine, or 2'9 parts in 1000. Not having been provided with a proper press, consi- derable loss was unavoidably sustained in both these experiments, which were also made on a smaller scale than is recommended in the text. The average of the two agrees exactly with the result obtained by the author, namely, from fowl 3'05 parts in 1000. W. G. CHEMICAL HISTORY OF KREATINE. 47 detect kreatine in the substance of the brain, of the found in the liver, or of the kidneys ; but it is present in abun- or kidneys', dant quantity in the heart of the ox, so that this heart con- organ is especially adapted for its preparation. The study of the substance of the brain and liver presented a number of peculiarities, which promise valuable results on a closer investigation. Thus, for example, when the substance of the brain is Pecuiiari- . ties worthy rubbed with barytic water to a thin emulsion, O f investu passed through a fine hair-sieve, and heated to boil- ing, there is obtained a coagulum, in which is con- tained all the fat of the brain, and a clear yellowish liquid, which when deprived of the excess of baryta by a current of carbonic acid gas, and subsequent boiling, contains two salts of baryta, one of which is soluble in alcohol. Both are soluble in water, and give with acids a white flocculent precipitate. uijco Kreatine. The crystals of kreatine, obtained as above de- Purification scribed, are separated from the mother liquid by a filter, washed, first with a little water, then with alcohol, and dissolved in boiling water. If the solution should be coloured, some animal charcoal (from blood) is added, and a very small quantity is sufficient to give a liquid which, when filtered, is colourless and limpid, and which, on cooling, de- posits the kreatine in perfectly pure crystals. If the phosphoric acid has not been entirely 48 ANALYSIS OF KREATINE. % removed by means of baryta, then the original crystals are mixed with phosphate of magnesia, of which the greater part is left behind on recrystallisa- tion ; but a small portion dissolves and is deposited along with the crystals of kreatine. To remove this impurity, the filtered solution is boiled with a little hydrated oxide of lead, filtered, and then treated with a little animal charcoal, which absorbs the traces of oxide of lead that may have been dis- solved. Description The crystals of kreatine are colourless, perfectly tais. transparent, and of the highest lustre ; they belong to the klinorhombic system, and form groups, the character of which is exactly similar to that of sugar of lead. At 212, the crystals become dull and opaque, with loss of water. Analysis of 0*485 gramme of crystallised kreatine lost at 212, 0-059 gramme of water = 12-16 per cent. 0-3582 gm. of crystallised kreatine lost at 212, 0-044 gm. of water = 12-28 per cent. 0*5835 gm. of crystallised kreatine lost at 212, 0*0705 gm. of water = 12-08 per cent. 0-603 gm. of crystallised kreatine lost at 212, 0*0753 gm. of water = 12*18 per cent. Hence 100 parts lost, on an average, at 212, 12*17 parts of water of crystallisation. The combustion of dried as well as of crystallised kreatine with oxide of copper, yielded a gaseous mixture which contained, for 388 volumes of nitrogen, 1,036 vol. of carbonic acid. Hence krea- ANALYSIS OF KREATINE. 49 tine contains, for 8 vol. of carbonic acid or 8 eqs. of carbon, 3 vol. or eqs. of nitrogen.* Further, in combustion with chromate of lead, 0-5628 gm. of crystallised kreatine yielded 0-6764 gm. of carbonic acid. (The water was lost in this analysis.) 0*5830 gm. of crystallised kreatine yielded 0-693 gm. of carbonic acid, and 0*388 gm. of water. 0*545 gm. of crystallised kreatine yielded 0*658 gm. of carbonic acid, and 0*367 of water. 0*2884 gm. of crystallised kreatine yielded 1*300 gm. of the double chloride of platinum and ammo- nium, = 28*32 per cent, of nitrogen. These analyses yielded, for 100 parts of kreatine : I. II. HI. Carbon 32'77 32'91 32'41f Nitrogen 28'32 28*32 28'32 Hydrogen 7'33 7'39 Oxygen 3144 31*88 100-00 100-00 * The 2nd tube gave for 89 vol. nitrogen 217 vol. carbonic acid. 3rd 64 156 4th 78 219 5th 77 224 6th 80 220 Total 388 1036 f In combustion with chromate of lead, it is well known that the formation of nitrous acid is unavoidable, and the excess of carbon in the above analysis arises, no doubt, from a small quan- tity of nitrous acid which had escaped the reducing action of the metallic copper in the anterior part of the tube. E 50 ANALYSIS corresponding to the formula, Formula. 8 eq. Carbon 48 32'22 3 eq. Nitrogen 42 28'19 11 eq. Hydrogen 11 7'38 6 eq. Oxygen 48 32'21 N Atomic weight of crystallised Kreatine 149 lOO'OO Anhydrous 0*3145 gm. of anhydrous kreatine yielded, when burned with oxide of copper, 0*4195 gin. of carbonic acid, and 0*197 gm. of water. 0*4085 gm. of anhydrous kreatine, burned with chromate of lead, yielded 0*5590 gm. of carbonic acid, and 0*2348 gm. of water. These analyses give in 100 parts (C : N = 8:3): I. II. Carbon 36-38 36'93 Nitrogen 31-91 32*39 Hydrogen 6'96 6'96 Oxygen 24'75 23-72 100-00 100-00 corresponding to the formula, Itsformula. 8 eq. Carbon 48 36*64 3 eq. Nitrogen * * 42 32'06 9 eq. Hydrogen 9 6'87 4 eq. Oxygen 32 24'43 Atomic weight of anhydrous Kreatine 131 100 '00 The crystallised kreatine corresponds, therefore, to the formula, Formula of 1 eq. anhydrous kreatine ... 131 87*92 thecrystals. 2 eq. water 18 12*08 149 100-00 OF KREATINE. 51 If we compare the formula of kreatine with that Kreatine arid glyco- of glycocoll (sugar of gelatine), it appears that crys- coil, tallised kreatine contains the elements of, 2 eqs. glycocoll = C 8 N 2 H 8 O 6 -f 1 eq. ammonia = N H 3 C 8 N 3 H u 6 Kreatine dissolves easily in boiling water, and a Properties J of kreatine. solution saturated at 212 forms, on cooling, a mass of small brilliant needles. From a diluted solution it crystallises very slowly, in somewhat large crys- tals, often from 2 to 3 lines in length and 1 line in thickness, which increase in size for 24 hours after cooling, if left in the liquid. 1,000 parts of water at 64*4 dissolve 13*44 parts of kreatine ; or 1 part of kreatine dissolves in 74*4 parts of water. In cold alcohol kreatine is nearly insoluble, 1 part requiring 9,410 parts of alcohol for solution. In weaker spirits of wine it is rather more soluble. The cold aqueous solution of kreatine possesses, from the small quantity of dissolved matter, a weak, bitter taste, followed by a somewhat acrid sensation in the throat. When the aqueous solution of krea- tine contains a trace of foreign organic matter, it decomposes very readily, as Chevreul observed. Mouldy vegetations appear, and the liquid acquires an offensive, nauseous odour. No quantity, however large, of kreatine can Kreatine is . neither acid destroy the acid reaction even of the weakest acids ; E2 52 ACTION OF ACIDS ON KREATINE. nor basic, it possesses no basic characters. It dissolves easily with the aid of heat in barytic water, and crystal- lises from it unchanged. The crystals which are deposited contain no baryta, and all the baryta in the solution is precipitated by carbonic acid. But when boiled with baryta water, kreatine is decom- posed ; ammonia is disengaged ; the liquid becomes turbid, even when the air is entirely excluded, and there is deposited carbonate of baryta in crystalline grains, the quantity of which progressively increases as the boiling is continued. In the warm saturated solution of kreatine, the colour of hyperoxide of lead is not changed, not even when boiled ; the crystals of kreatine deposited in cooling are free from oxide of lead. A solution of hypermanganate of potash, in which kreatine is dissolved, only loses its red colour by long digestion with the aid of heat, without perceptible disengage- ment of gas. The liquid now contains no kreatine, and gives on evaporation white crystals; while the potash is found partly combined with carbonic acid. Action of The action of strong mineral acids is very remark- kreatine. able. A solution of kreatine, to which, while cold, hydrochloric acid is added, gives by spontaneous evaporation crystals of unchanged kreatine. But when heated with strong hydrochloric acid, a solu- tion of kreatine no longer yields crystals of that substance. The same result is obtained with sul- phuric, phosphoric, and nitric acids. When krea- KREATININE. 53 tine is dissolved in one of these acids, and the solu- tion gently evaporated, crystals are obtamed, which are very soluble in alcohol, a property not belonging to kreatine. These crystals contain a portion of the acid employed, in a state of combination. There is formed, in this reaction from kreatine, Kreatinine. by a transformation of its elements, caused by con- tact with strong mineral acids, a new body of totally different chemical properties, a true organic alkali, which I shall call Kreatinine. Kreatinine. When crystallised kreatine is exposed, in the Formation of kreati- drying apparatus described by me, to a current of nine, by means of dry hydrochloric acid gas, at the temperature of hydrochio- 212, the weight of the apparatus at first increases ; but by continuing the heat and the current of gas, the original weight is at last very nearly recovered. Although it thus appears as if kreatine under these circumstances could absorb no hydrochloric acid, this conclusion is at once found to be erroneous, because during the whole continuance of the expe- riment water is seen to pass off, till the weight of the apparatus becomes constant. If anhydrous kreatine be used for this experiment, an increase of weight is found to take place. The compound formed in these circumstances is neutral hydrochlorate of kreatinine. In like manner, hydrochlorate of kreatinine is obtained, when kreatine is covered with concen- 54 KREATININE. trated hydrochloric acid in a porcelain dish, and the solutione vaporated in the water-bath till all uncom- bined hydrochloric acid is dissipated. or by means When kreatine is mixed with diluted sulphuric of sulphuric acid. acid (for 1 part of kreatine, 1 part of an acid, composed of 27 parts oil of vitriol, and 73 parts water), the solution being evaporated to dryness, and heated till all moisture is expelled, neutral sulphate of kreatinine is left. From the hydrochlorate or the sulphate, prepared in either of the above ways, kreatinine may be easily obtained. Separation When carbonate of baryta is added to a boiling nine from aqueous solution of the sulphate of kreatinine, till phate, no more effervescence ensues, and the liquid has an alkaline reaction, sulphate of baryta is deposited, and pure kreatinine remains in solution. and from From the hydrochlorate the base is obtained, chlorate when the aqueous solution of the salt is boiled with hydrated oxide of lead. The hydrochlorate is dis- solved in from 24 to 30 parts of water, the solution heated to boiling in a porcelain vessel, and hydrated oxide of lead suspended in water is added in small portions. At first chloride of lead is formed, and the liquid retains its acid reaction ; but when more oxide of lead is added, it becomes neutral, or slightly alkaline. If now there be added to the mixture a quantity of oxide of lead three times as great as that already employed, and the whole is kept boiling for some time, a point is at last reached, KREATININE. 55 at which the liquid, no matter how much diluted, seems to be converted into a thick, light, yellow pasty mass. The decomposition is then complete ; the liquid is filtered and the residue carefully washed. Should a trace of oxide of lead be dis- Purification solved or suspended in the filtered liquid, it is nine. easily removed by means of a little animal charcoal. This process depends on the conversion of the chlo- ride of lead into a basic compound with oxide of lead, which is as insoluble in water as chloride of silver. The solution of kreatinine thus obtained is entirely free from chlorine, and yields, as does also the solu- tion prepared from the sulphate by baryta, on eva- poration, perfectly formed crystals of kreatinine. As, in both methods, all the impurities contained in the carbonate of baryta, or in the oxide of lead, which may contain acetic acid or potash, are left in the solution of kreatinine, it is necessary to bestow particular attention on the perfect purification of the carbonate of baryta or hydrated oxide of lead, which are to be used for this purpose. The crystals of kreatinine belong to the monokli- Description nometric system, and are formed by the prism oo P, ta\ s . 6 CryS the basic terminal face o P, and klinodiagonal ter- minal face oo P oo . The orthodiagonal is less than the klinodiagonal. The angle o P : oo P oo, that is, the angle of inclination of the principal axis on the klinodiagonal, was found to be = 69 24' ; the angle under which the lateral faces oo P meet in the 56 CHARACTERS OF KREATININE. orthodiagonal section, = 98 20', and in accordance with this, the angle which oo P oo forms with oo P, = 130 50'.* Kreatinine is much more soluble in cold water than kreatine. 1,000 parts of water dissolve 87 parts of kreatinine, or 1 part dissolves in 11*5 parts of water at 60. In hot water it is much more soluble. The aqueous solution restores the blue of red- dened litmus paper, and a crystal, laid on moist turmeric paper, causes a brown stain at the point of contact. Kreatinine dissolves in boiling alcohol, and crys- tallises on cooling. 1,000 parts of alcohol at 60 dissolve 9*8 parts of kreatinine. Kreatinine In its chemical character, kreatinine is quite is analogous to ammo- analogous to ammonia. nia. its action A moderately concentrated solution of nitrate of snver, rate f s ^ ver ? when kreatinine is added to it, instantly forms a mass of small white needles, which are very solu- ble in hot water, and crystallise from it unchanged on cooling. They are a basic compound of kreati- nine and nitrate of silver. oncom>- In a solution of corrosive sublimate, kreatinine sive subli- . . . mate, causes at once a white curdy precipitate, which, in a few minutes, changes to a mass of slender trans- parent colourless needles. on chloride In a neutral aqueous solution of chloride of zinc, of zinc, * The crystallometric measurements given in this work have been made by Dr. Kopp. COMPOSITION OF KREATININE. 57 kreatinine causes instantly a precipitate formed of crystalline grains, appearing under the microscope as round masses, formed of very small needles concen- trically grouped. Kreatinine expels ammonia from ammoniacal on salts of ammonia, salts, and forms with salts of oxide of copper crystal- and on salts lisable double salts of a fine blue colour. Bichloride of platinum, when hydrochlorate of onbichior- . . ITT . ide of plati- kreatmine is added to it, causes no precipitate it. num. the solution is diluted; but on evaporation in a gentle heat, there are formed deep yellow transpa- rent crystals of considerable size, very soluble in water, less so in alcohol. A solution of kreatinine to which bichloride of platinum and hydrochloric acid have been added, yields, when evaporated, the same compound, which is a double salt analogous to the double chloride of platinum and ammonium. The composition of kreatinine is easily deduced Thecompo- from the action of hydrochloric acid gas on kreatine. kreatinine 0*5775 gm. of kreatine in crystals increased in fromitsfor- weight when exposed to a current of that gas, at 202 by only 0-002 gm. The residue, dissolved in water, and precipitated by nitrate of silver, gave 0-5605 gm. chloride of silver, corresponding to 24-68 per cent, of hydrochloric acid. The fact that the weight is not altered in this experiment, implies that for 24*68 parts of hydro- chloric acid absorbed, an equal or very nearly equal weight of water has been expelled. 58 FORMATION OF KREATININE. Now since crystallised kreatine, when heatecl alone to 212, loses 12-08 per cent, of water, it is evident that twice this quantity has been expelled, because otherwise, when 24-68 per cent, of hydro- chloric acid had been absorbed, the weight must have increased. Since, moreover, 1 eq. of hydro- chloric acid weighs 36'5 (H=l) and that weight corresponds to 4 eq. of water, it follows that for 1 eq. of hydrochloric acid absorbed, 4 eqs. of water have been expelled. It follows further, that anhydrous kreatine must gain in weight when exposed to hydrochloric acid gas, to the amount of 14-05 per cent. In fact, 0'5820 gm. of anhydrous kreatine, under these cir- cumstances, absorb 0*084 gm. of hydrochloric acid, corresponding to 14-46 per cent., a coincidence as close as could be obtained. Kreatine, in The conversion of kreatine into kreatinine, by the action of mineral acids, depends, therefore, on the separation of 4 eqs. of water. If we subtract these from the formula of crystallised kreatine, the com- position of kreatinine in 100 parts is as follows : Formula. 8 eqs. Carbon = 48 42'48 3 eqs. Nitrogen =42 37' 17 7 eqs. Hydrogen = 7 6' 19 2 eqs. Oxygen =16 14' 16 ; of 1 Atomic weight of , ~. ,. . I 113 100-00 Kreatinine Analysis of i n accordance with this theoretical result there kreatinine. ANALYSIS OF KREATININE. 59 were obtained by combustion with chromate of lead the following numbers : 0-3418 gm. of kreatinine yielded 0*5332 gm. car- bonic acid, and 0*1965 gm. water. The same substance yielded, when burned, a gaseous mixture, in which, for 434 volumes of nitro- gen gas, there were found 1,132 vol. of carbonic acid.* According to this analysis, kreatinine contains Carbon 42'54 Nitrogen 37'20 Hydrogen .. 6'38 Oxygen 13'88 100-00 If we compare with the formula of kreatinine that Kreatinine and caffeine. of caffeine (theme), it appears, that kreatinine con- tains the elements of 1 atom of caffeine + 1 atom amide. Caffeine is C 8 N 2 H 5 O 2 : add to this 1 at : Amide N H 2 The sum is C 8 N 3 H 7 O 2 = 1 at : Kreatinine. N. CO 2 * The 2nd tube yielded 75 for 187 3rd 77 197 4th 79 207 5th 48 126 6th 70 200 7th 85 , 215 N:CO 2 = 3:8 434 1132 60 KREATINE AND KREATININE ARE The com- pound dis- covered in urine by Pettenko- fer contains the same pro- portions of carbon and nitrogen as kreatineand kreatinine. Pettenko- fer's pro- Kreatine and Kreatinine, constituents of human urine. If we compare the results of the analysis of krea- tine and kreatinine with the composition of the substance discovered three years since by Petten- kofer * in human urine, and analysed by him, we perceive at once, that both kreatine and kreatinine must stand in a definite relation to that body. Pettenkofer found that this substance, when burned, yielded a gaseous mixture, containing, for 8 vol. of carbonic acid, 3 vol. of nitrogen. This is the same proportion, as is contained in kreatine and kreati- nine; although, on the other hand, he found a variation in the proportion of hydrogen and oxygen. The substance from urine contains 1 eq. of water less than anhydrous kreatine and 1 eq. more than kreatinine. Although I had no reason to doubt the accuracy of Pettenkofer's analysis, yet T considered it desir- able to compare the properties of the substance from urine with those of kreatine and kreatinine. According to Pettenkofer's process for its prepa- ration, fresh human urine is neutralised with carbo- nate of soda, evaporated till the salts crystallise out, then extracted by alcohol, and mixed with a con- centrated solution of chloride of zinc. In this mixture, there are deposited, after some hours or days, small granular hard crystals, frequently in crusts, which contain chloride of zinc and a crystal- * Annalen der Chemie und Pharmacie, vol. lii. p. 97. CONSTITUENTS OF HUMAN URINE. 61 Usable organic substance. When these crystals are dissolved in hot water, the zinc separated by means of baryta, the filtered liquid evaporated, the residue acted on by alcohol, the alcoholic solution deprived of baryta by sulphuric acid, and the liquid, which now contains hydrochloric acid, sulphuric acid, and the organic compound, boiled with oxide of lead, the sulphuric and hydrochloric acids are thus separated, and the organic compound remains dis- solved in alcohol, and gives on evaporation a crys- talline white mass, which instantly reproduces the original crystalline precipitate when its solution is mixed with chloride of zinc. According to my experiments, this substance may simpler be obtained from urine by a simpler process. The proposedby urine is neutralised by milk of lime, and then solution of chloride of calcium is added as long as it causes a precipitate of phosphate of lime. The liquid is then filtered and evaporated till the salts crystallise out on cooling. The mother liquor is separated, without the use of alcohol, from the salts, and mixed with a syrupy solution of neutral chloride of zinc, in the proportion of about ^ ounce to 1 Ib. of the extract. After three or four days the greater part of the zinc-compound of Pettenkofer is found to have crystallised in rounded yellow grains. The deposit is well washed with cold water, then dissolved in boiling water, and hydrated oxide of lead added to the solution, till it acquires a strong alkaline (52 PETTENKOFER'S COMPOUND CONSISTS reaction. By this means the zinc and hydrochloric acid are separated in an insoluble form, while the substance, formerly combined with them, remains in solution. This is now acted on with blood-charcoal, which removes a yellow colouring matter and a trace of oxide of lead, and the filtered liquid is evapo- rated to dryness. Pettenko- By the process of Pettenkofer, as well as by that stance is a just described, there was obtained a white crystalline substance, having, in each case, the same characters. kreatine. e But a closer investigation immediately showed that this substance was a mixture of two compounds of different properties, which may easily be separated by means of alcohol, one of them being easily solu- ble, the other very sparingly soluble, in hot alcohol. When a portion of the mixed substance is boiled with 8 or 10 times its weight of alcohol, either a part remains undissolved, or the solution is complete, but deposits crystals on cooling. These crystals are found to be identical with the undissolved residue. When they are separated from the mother liquor, and the latter evaporated, a new crystallisation, of different form and properties, is obtained. The body which crystallises first, or remains in the undissolved residue, contains water of crystallisation and has no action on vegetable colours ; the more soluble has in its aqueous solution a strong alkaline reaction, its crystals do not effloresce when heated, and the analysis of these two compounds showed, as the external form and chemical characters indicated, OF KREATININE AND KREATINE. 63 that the one which first crystallised was kreatine, the Analysis of other kreatinine. The kreatine thus prepared from urine yielded, when burned with oxide of copper, a gaseous mixture containing, for 3 vols. of nitrogen, 8 vols. of carbonic acid.* 0-6085 gm. lost at 212, 0-0775 gm. of water, = 12*77 per cent. 0-3686 gm. yielded 0*500 gm. of carbonic acid and 0-2348 gm. of water. That ingredient of Pettenkofer's substance which was most soluble in alcohol (kreatinine) gave, when burned, a gaseous mixture in which nitrogen and carbonic acid were in the proportion of 280 N to 740 C 2 , or of 3 vols. nitrogen to 8 vols. carbonic acid.f Further, 0'3767 gm. of the same body yielded 0-589 gm. carbonic acid and 0*2112 gm. water. N. C O 2 . * The 2nd tube yielded 72 for 190 3rd 78 205 4th 74 198 5th 55 202 6th 86 177 365 972 N. C 2 . t The 2nd tube yielded 52 for 142 3rd 71 189 4th 69 183 5th 88 226 280 740 64 KREATININE IN PUTRID URINE. tion of the substances fromurine ' They are inthepu- appears. The composition of these two substances in 100 parts is therefore, Kreatinefrom Kreatinine Urine (anhydrous), from Urine. Carbon ............... 36'90 42'64 Nitrogen ............... 32*61 37'41 Hydrogen ............ 7'07 6'23 Oxygen ............... 23-42 13'72 100-00 100-00 If we compare these numbers with those obtained by the analysis of kreatine from flesh, and the analysis of the kreatinine prepared from it, it is obvious that they are respectively identical, and indeed no difference can be detected in the physical and chemical characters of the two substances from urine and those from flesh. It has been stated, that the two substances, which served for the preceding analysis, were obtained from fresh urine ; but it seemed to me to be inter- esting, to ascertain the influence which the putre- faction of the urine has on these substances. When putrid urine, in which, of course, all the urea nas been converted into carbonate of ammonia, * s boiled with milk of lime till ammonia is no longer disengaged, then filtered, evaporated to a thin syrup, and in this state mixed with chloride of zinc, there separates in the course of a few days a considerable quantity of a yellow granular compound, which con- tains chlorine and zinc, and under the microscope cannot be distinguished from the compound formed by chloride of zinc in fresh urine. When dissolved FORMATION OF PETTENKOFER's COMPOUND. 65 in boiling water, and deprived of chloride of zinc and colouring matter by means of hydrated oxide of lead and blood-charcoal, the organic substance con- tained in it was found to be kreatinine, without a trace of kreatine. During the putrefaction of urine, therefore, the kreatine is destroyed, while the kreatinine suffers no change. I consider kreatine to be an accidental and vari- able ingredient of Pettenkofer's zinc compound ; for a warm (not boiling) solution of kreatine is not precipitated by chloride of zinc, and the crystals which are deposited contain neither zinc nor chlorine, but possess all the characters of pure kreatine. It is clear that if the fresh urine contain kreati- Formation nine in combination with an acid, and free kreatine, kofer's^ the kreatinine, when it is neutralised by an alkali, com P und - will be set free, and when the liquid is concen- trated to ^th of its original volume, the addition of chloride of zinc will precipitate the compound of chloride of zinc with kreatine ; but the crystals of this substance will be mixed with those of krea- tine, whenever the quantity of kreatine present is more than the liquid can retain in solution when cold. Although the amount of kreatine and kreatinine, Urine is an ir, i p . . .111 T economical to be obtained from urine, is not considerable, yet I source of consider the preparation of these substances from and kreati- urine to be more convenient, and especially more 66 SALTS OF KREATININE. economical, than their extraction from flesh ; and by either of the processes just described, they may be obtained in any required quantity by operating on a sufficiently large scale. Hydrochio- Hydrochlorate of Kreatinine. This salt, the pre- kreatinine. paration of which has been already described, dis- solves readily in boiling alcohol, and crystallises from it in short, transparent, colourless prisms, very soluble in water ; it is obtained by evaporating its aqueous solution in broad transparent scales of an acid reaction. A saturated solution of this salt in boiling alcohol, to which ammonia is added till the acid reaction is destroyed, deposits on cooling small transparent granular crystals of kreatinine. 0*4764 gm. of hydrochlorate of kreatinine yielded 0*5677 gm. carbonic acid and 0*227 water. Further, 0*542 gm. yielded 0*513 gm. chloride of silver. This gives in 100 parts, 8 eqs. Carbon . ... ... 48 Calculated. 32-30 Found. 32-48 3 eqs Nitrogen ... 42 28-11 28-27 8 5*35 5-30 2 eqs Oxygen ... 16 10*55 10-54 1 eq. Chlorine ... 35-4 23-69 23-41 Atomic Weight 149*4 lOO'OO 100-00 Double Chloride of Platinum with hydrochlorate of kreati- bichioride nine. A solution of hydrochlorate of kreatinine U gives, on the addition of bichloride of platinum, and gentle evaporation, aurora-red prisms of the double SALTS OF KREATININE. 67 salt. When more rapidly formed, this salt is ob- tained in yellowish-red transparent grains. 0-6086 gm. of this salt made with kreatine pre- pared from flesh, left after ignition, 0-1858 gm. platinum. 0-8608 gm. of the same salt, prepared with Pet- tenkofer's compound, derived from urine, left 0*2665 gm. platinum. Hence this double salt consists of Calculated. Found. Kreatinine and Hydrochloric acid... 69'05 69-47 69'05 Platinum , 30'95 30'53 30'95 100-00 100-00 100-00 Sulphate of Kreatinine. A boiling saturated so- Sulphate of kreatinine. lution of kreatinine, to which diluted sulphuric acid is added, till a strong acid reaction appears, gives on evaporation a white saline mass, easily dissolved by hot alcohol. While cooling, the solu- tion becomes milky, and deposits (on becoming clear) transparent, concentrically -grouped, four- sided tables of neutral sulphate of kreatinine, the crystals of which salt continue transparent when heated to 212. 0-439 gm. of sulphate of kreatinine yielded 0*315 gm. of sulphate of baryta. 0*5655 gm. of the same salt gave, when burned, 0*6085 gm. of carbonic acid, and 0*2563 gm. of water. F2 SARCOSINE. Hence this salt consists of 1 eq. Sulphuric acid 40 8 eq. Carbon 48 3 eq. Nitrogen ... 42 8 eq. Hydrogen... 8 3 eq. Oxygen ... 24 1 eq. Kreatinine . . . Calculated. 24'69 29'63 25-92 4-94 14-82 Found. 24-65 29-33 25-44 5-03 15-55 1 eq. Sulphate of Kreatinine =162 100' 00 100' 00 Sarcosine. Action of When, to a boiling saturated solution of kreatine, ryticwater we add ten times the weight of the kreatine of * crystallised hydrate of baryta, the solution continues clear at first, but by continued boiling it becomes turbid, and deposits a white crystalline powder, adhering to the sides of the vessel, which increases as long as the disengagement of ammonia continues. If the boiling be continued, baryta and water being added from time to time, until no further escape of ammonia is perceptible, there is obtained by filtra- tion a transparent colourless liquid, which contains caustic baryta along with a new organic base, to which I have given the name of Sarcosine. The white powder remaining on the filter contains no organic matter, and is pure carbonate of baryta. By passing a current of carbonic acid gas through the liquid, and subsequently boiling, the baryta is separated from the new base, which remains dis- solved ; and the solution, when evaporated, gives a syrup, which on standing consolidates into a mass of Sarcosine. Its purifi- cation. PURIFICATION OF SARCOSINE. 69 broad, colourless, transparent plates. For the pre- paration of pure sarcosine, it is important to use perfectly pure baryta, previously tested for, and if necessary deprived of, traces of potash, lime, chlo- rine or nitric acid ; because all such impurities accumulate in the sarcosine, from which they cannot easily be removed. To obtain pure sarcosine, it is advisable to convert it, as prepared by the process just described, into sulphate. For this purpose, diluted sulphuric acid is added to the base obtained by the evaporation of the filtered liquid, till it acquires a strong acid reac- tion. The acid solution is evaporated in the water- bath, and to the syrupy residue alcohol is added, and well mixed with it by means of a glass rod. The syrupy sulphate is thus converted into a white crystalline powder, which is well washed with cold alcohol, then dissolved in water, and the solution digested with pure carbonate of baryta in a warm place, till no further effervescence ensues, and the acid reaction has disappeared. The liquid now contains the pure base dissolved ; it is filtered from the sulphate and carbonate of baryta, evaporated in the water-bath to a syrup, and in this state set aside. The sarcosine crystallises in from 24 to 36 hours. The crystals of sarcosine are right rhombic Crystals of prisms; acuminated on the ends by surfaces set perpendicular on the obtuser angles of the prism, that is, the combination oo p : P oo. Only the faces 70 ANALYSIS OF SARCOSINE. oo P had lustre enough to admit of approximative measurement ; the angles of the prism were found = 103 and 77. Single planes of P and o P occur rarely, and then doubtfully indicated. The crystals its proper- are colourless, perfectly transparent, and of consi- ties. derable size. They are extremely soluble in water, very sparingly soluble in alcohol, and insoluble in ether. When dried at 212, they retain their ori- ginal aspect ; at a somewhat higher temperature they melt, and sublime without residue. When some crystals of sarcosine are exposed, between two watch-glasses, for a long time to a heat of 212, the upper glass is covered with a network of crystals of sublimed sarcosine. Analysis of The analysis of sarcosine gave the following re- sults. When burned with the oxide of copper, it gave a gaseous mixture, containing 1 vol. of nitrogen for 6 vols. of carbonic acid.* It therefore contains, for 6 eqs. of carbon, 1 eq. of nitrogen. 0*3843 gm. of sarcosine yielded, further, 0*574 gm. of carbonic acid, and 0*2735 gm. of water. 0*3666 gm. yielded 0*550 gm. of carbonic acid and 0*2578 gm. of water. N. C O 2 . * The 2nd tube yielded 42 233 3rd 38 241 4th 40 230 5th 40 243 6th 43 252 203 1,199 sarcosme. PROPERTIES OF SARCOSINE. / 1 This gives for 100 parts Formula of Calculated. Found. 6 eq . Carbon 36 40-45 40-73 40-90 1 eq. Nitrogen ... 14 15-73 15-84 15-90 7 eq. Hydrogen... 7 7-86 7-90 7-82 4 eq. Oxygen ... 32 35-96 35-53 35-38 sarcosme. 1 eq. Sarcosine... 89 lOO'OO lOO'OO 10OOO The aqueous solution of sarcosine has no action Properties . ofsarco- on vegetable colours ; it has a sweetish, sharp, some- sine. what metallic taste ; in diluted solutions of nitrate of silver and corrosive sublimate it causes no change. But if a crystal of sarcosine be placed in a cold saturated solution of corrosive sublimate, it is instantly dissolved, and in a short time there are seen to be formed a number of slender transparent needles of a double salt, which, if the quantity of sarcosine is not too small, fill the whole liquid, con- verting it into a semi-solid mass. A solution of acetate of copper acquires, by the addition of sar- cosine, the same deep blue colour as is caused by ammonia, and by gentle evaporation there are ob- tained thin scales of the same colour. When evaporated along with hydrochloric acid, Hydrochio- . , , rate of sar- sarcosine yields a white saline mass, which dissolves cosine. in hot alcohol, and is deposited on cooling in small transparent grains and needles. A solution of hydrochlorate of sarcosine, mixed Double salt . , withbichlo- with excess of bichloride of platinum, gives no rideofpia- . 1 tinutn. precipitate ; but by spontaneous evaporation it soon forms flattened octohedrons of a honey-yellow colour, 72 SALTS OF SARCOSINE. which often exhibit faces half an inch broad, lying on each other in the manner of the steps of stairs. By means of a mixture of alcohol and ether, the superfluous bichloride of platinum is easily re- moved, and the crystals may thus be obtained quite pure. Analysis of The double chloride of platinum' and sarcosine, sail l dried in the air, loses, when further heated to 212, 6*7 per cent, of water. 0*4544 gm. of the anhydrous salt yielded on igni- tion 0*1527 gm. of platinum. If this salt have a composition analogous to that of the double chloride of platinum and ammonium, it would contain In 100 Parts. Theory. Experiment. Its for- 1 eq. Sarcosine 89 1 mula - 1 eq. Hydrochloric acid 36'4 > 196'2 66'85 66'40 2 eqs. Chlorine 70-8J 1 eq. Platinum 98'7 33*45 33'60 1 eq. of the anhydrous double salt 294'9 lOO'OO lOO'OO The Joss of weight at 212 indicates that the crystallised salt contains 2 eqs. of water = 5*7 per cent. Sulphate of Sulphate of Sarcosine. The preparation of this salt has been already described (p. 69). When the residue, well washed with cold alcohol, is boiled with from 10 to 12 times its weight of alcohol, it dissolves, with the exception of a trace of sulphate of baryta; and this solution deposits on cooling transparent colourless four-sided tables of high SALTS .OF SARCOSINE. 73 lustre, which can hardly be distinguished by their aspect from chlorate of potash. -They are sparingly soluble in cold alcohol, but very soluble in water, and crystallise from their aqueous solution in large feathery plates. Both the aqueous and alcoholic solutions have a strong acid reaction, so that it is difficult to tell when the washing of them, to remove uncombined acid, is complete. On this account the following analyses of this salt have given a slight excess of sulphuric acid. 0*6928 gm. of sulphate of sarcosine lost, at 21 2, Analysis of 0*049 gm. of water = 6*54 p. c. ; and yielded 0*5470 gm. of sulphate of baryta = 29*25 p. c. of sul- phuric acid in the anhydrous salt. 0*5899 gm. of sulphate of sarcosine lost, at 212, 0-0385 gm. of water = 7*07 p. c. ; and gave 0*4870 gm. of sulphate of baryta, = 30*36 p. c. of sul- phuric acid in the anhydrous salt. I. 0*3745 gm. of this last portion of sulphate of sarcosine (= 0*2608 gm. after deducting the sul- phuric acid) gave 0*3475 gm. of carbonic acid. II. 0*3388 gm. of the same salt (= 0*2389 gm. after deducting the acid) gave 0*3087 gm. of car- bonic acid, and 0*1735 gm. of water. III. 0*2674 gm. of sulphate of sarcosine (= 0*1865 gm. after deducting the acid) gave 0*2475 gm. of carbonic acid, and 0*138 gm. of water. If sulphate of sarcosine be analogous in compo- sition to the sulphates of other organic bases, the anhydrous salt contains 1 eq. of sarcosine com- 74 SULPHATE OF SARCOSINE. bined with 1 eq. of hydrated sulphuric acid, and therefore, in calculating the analyses, if we deduct the weight of anhydrous sulphuric acid present, we must obtain in the remainder a formula which includes the elements of sarcosine + 1 eq. of water. Formula of The formula C 6 N H 7 4 + H O would yield in sarcosine in the sui- 100 parts phate ' Theory. Experiment. 6 eqs. Carbon ... 36 36'73 36'34 35'69 36-28 1 eq. Nitrogen... 14 8 eqs. Hydrogen 8 8' 16 7'90* 8' 16 8' 25 5 eqs. Oxygen... 40 98 The loss sustained by the crystallised salt at 212 indicates the presence of 1 eq. of water of crystal- lisation = 6*1 per cent. The Sulphate of Sarcosine, when heated to 212, consists of Calculated. Found. 1 eq. Sulphuric acid 40 28-98 29-25 30*36 1 eq. Sarcosine 89 J 71-02 70-75 69-64 1 eq. Sulphate of Sarcosine 138 100-00 100-00 100-00 I regret much that want of material prevented me from multiplying experiments with this inter- * The hydrogen in this analysis fell below the truth, which arose from the circumstance, that the salt was decomposed by mixture with chromate of lead, and the water of the sulphuric acid being set free, a portion of it was lost in the process of exhausting the tube previous to the combustion. FORMATION OF SARCOSINE. 75 esting base: but I believe that no doubt can be entertained as to its composition and its atomic weight. The formula above given for sarcosine explains Formation . of sarcosine its production from kreatme in a satisfactory explained. manner. If from the elements of crystallised kreatine we subtract those of sarcosine, there remains a for- mula exactly identical with that of urea. From 1 eq. Kreatine = C 8 N 3 H u O 6 Deduct 1 eq. Sarcosine = C 6 N H 7 O 4 There remains 1 eq. Urea = C 2 N 2 H 4 O 2 Kreatme contains the ele- ments of sarcosine and of urea. It is consequently obvious that, in the decompo- sition of kreatine by baryta, carbonic acid and ammonia are secondary products derived from the decomposition of urea. I have ascertained that a solution of urea in barytic water is resolved by long boiling into carbonate of baryta and ammonia with the same appearances as those above described ; and I have also ascertained that urea is present in urea is the liquid when kreatine is boiled with baryta, if theproceL examined before the whole of the kreatine is decom- posed. If the operation be arrested when the disengagement of ammonia is strongest, the free baryta precipitated by carbonic acid, the liquid filtered and evaporated to dryness, and nitric acid added to the residue, there is obtained a crystalline mass, which when dried in blotting paper and treated with alcohol, yields to that solvent nitrate 76 COMPOSITION OF SARCOSINE. of urea. If the alcoholic solution be heated with oxide of lead, nitrate of lead is precipitated, and the liquid gives on evaporation colourless prisms, the concentrated aqueous solution of which forms with oxalic acid a crystalline precipitate. These prisms, when heated, melt easily, give off ammonia, and leave a white residue, which, when further heated, is dissipated in the form of the vapour of hydrated cyanic acid. Sarcosineis According to the formula established by the pre- isomeric withiacta- ceding analyses for sarcosine, it contains the same mide and withure- elements, and in the same relative proportions, as the lactamide of Pelouze and the urethane of Dumas. But the insolubility of sarcosine in ether and alcohol sufficiently distinguishes it from these two com- pounds. Sarcosine Sarcosine and urea are not, however, the only not the only products of the decomposition of kreatine by baryta. If water be added to the alcohol from which the sulphate of sarcosine has been crystallised, and the liquid neutralised by carbonate of baryta be filtered and evaporated to the consistence of a thin syrup, there are deposited, long before the point is reached at which sarcosine would crystallise, long colourless prisms or scales, of a feeble acid reaction, which at first for this reason I took for an acid. But they are fusible and volatile, without leaving a Another residue of baryta; they are very soluble in water an d alcohol, and also in 30 parts of ether; the aqueous solution causes no precipitate in nitrate of INOSINIC ACID. 77 silver, corrosive sublimate, acetate of lead, or in possibly salts of lime and baryta. Unfortunately I did not urethane< obtain a quantity sufficient for an analysis of this substance, so as to decide whether it agrees in composition with urethane, which it much resembles. Inosinic A cid. When the liquid from flesh, treated as formerly described, has entirely deposited the crystals of kreatine, and is somewhat further concentrated by evaporation, if alcohol be added to it in small quan- tities till the whole becomes milky, it deposits, when allowed to rest for some days, yellowish or white granular, foliated or acicular crystals, which may be separated from the viscid mother liquor, although slowly, by filtration, and may be washed with alcohol. These crystals are a mixture of many different substances, among which kreatine is invariably found. If the whole of the phosphoric acid has not previously been removed from the original solution of flesh, this deposit contains phosphate of mag- nesia; but the chief ingredient is the potash or baryta salt of a new acid, to which I shall give the name of Inosinic acid. If the quantity of baryta added has been exactly sufficient to precipitate the whole of the phosphoric acid, the crystals contain inosinate of potash ; and 78 INOSINIC ACID. finally, if the baryta has been added in excess, they consist of inosinate of baryta, or a mixture of these two salts, its purifi- To purify the acid, the deposit is dissolved in cation. hot (not boiling) water, and chloride of barium is added to the solution. On cooling, crystals of inosi- nate of baryta are deposited, which, by a recrystal- lisation, are rendered perfectly pure. Inosinic acid is easily prepared from the inosinate of baryta, by the cautious addition of sulphuric acid to separate the baryta ; or from the inosinate of copper by the action of sulphuretted hydrogen. The solution of the latter salt, after being decomposed by sulphuretted hydrogen, is generally brown and turbid, from suspended sulphuret of copper, but it is rendered colourless by a little blood-charcoal and filtration. its proper- Prepared by either process, the solution of the inosinic acid has a strong acid reaction, and pos- sesses an agreeable taste of the juice of meat. When evaporated, it yields a syrup, which, after weeks, exhibits no signs of crystallisation If this syrup be mixed with alcohol, the thick viscid fluid is changed into a hard, firm, pulverulent mass, of which alcohol dissolves only traces. From a concentrated aqueous solution the acid is precipitated in white amorphous flocculi. It is insoluble in ether. The quantity of this acid at my disposal was not sufficient for an analysis of it ; but the analysis of INOSINATE OF BARYTA. 79 the baryta salt is sufficient to determine the compo- sition of the acid. 0*312 gm. of inosinate of baryta, dried at 212, Analysis of . inosinate of yielded, when ignited with a mixture of soda and baryta. lime, 0*565 gm. of the double chloride of platinum and ammonium = 11*370 p. c. of nitrogen. The combustion of the inosinate of copper yielded a gaseous mixture, containing for 137 vols. of nitrogen 673 volumes of carbonic acid. This indi- cates that inosinic acid contains, for 1 eq. of nitrogen, 5 eqs. of carbon.* 0*4493 gm. of dried inosinate of baryta yielded 0*2043 gm. of sulphate of baryta = 30*07 p. c. of baryta. 0*5430 gm. of dried inosinate of baryta yielded 0*2546 gm. of sulphate of baryta = 30*75 p. c. of baryta. 0*4248 gm. of the same salt, burned with chro- mate of lead, yielded 0*381 gm. of carbonic acid, and 0*101 gm. of water. 0*4178 gm., burned with chromate of lead, yielded 0*380 gm. of carbonic acid, and 0*0975 gm. of water. N. C 2 . * The 2nd tube yielded 49 235 3rd 45 245 4th 42-5 193*5 136-5 673-5 N : C (X = 1 : 5. 80 INOSINATES. Hence, the anhydrous inosinate of baryta con- tains Formula of the anhy- drous salt. 10 eqs. Carbon 60 Calculated. 23-96 11-18 2-40 31-95 30-51 Found. 24'46 24*80 11-37 11-37 2-64 2-59 31-46 30-79 30-07 30-75 2 eqs. Nitrogen . . .. . 28 6 eqs. Hydrogen 6 10 eqs. Oxygen 80 1 eq Baryta . . . 76*4 1 eq. Inosinate of Bar yta... 250-4 100-00 100-00 100-00 Formula of After deducting the baryta, the anhydrous acid drousacid, combined with it contains 10 eqs. of Carbon, 2 eqs. of Nitrogen, 6 eqs. of Hydrogen, 10 eqs. of Oxygen ; and of the And if we suppose the baryta replaced by its acid e equivalent of water, the formula of inosinic acid will be C 10 N 2 H 7 O n = G 10 N 2 H 6 10 + H 0. inosinates. Inosinates. Free inosinic acid does not precipi- tate lime-water or barytic-water, but when these mixtures are left to evaporate in the air, there are formed transparent pearly scales of the inosinates of lime and baryta. The free acid, as well as its so- luble salts, cause a precipitate in acetate of copper ; the inosinate of copper appears as a fine greenish- blue precipitate, which does not dissolve even in boiling water, and is not blackened by it. Salts of silver are precipitated white by inosinates ; the pre- cipitate is gelatinous, of the aspect of hydrate of alumina, soluble in nitric acid and ammonia. In INOSINATE OF POTASH. 81 the salts of lead inosinic acid causes a white precipi- tate. The salts of inosinic acid with the alkalies are decomposed when heated on the platinum spatula, and give out a strong and agreeable smell of roast meat. Inosinate of Potash. This salt is obtained from inosinateof the baryta salt by cautious precipitation of the baryta by carbonate of potash, and also directly from the juice of flesh (see p. 77). It is yery soluble in water, and crystallises in long slender four-sided prisms. It is insoluble in alcohol, and is precipitated by it, even from diluted aqueous solutions, as a granular powder. The addition of alcohol to a concentrated solution of inosinate of potash causes it to become semi-solid, from the deposition of fine pearly scales. The following determination of the amount of potash was made with a specimen of the salt prepared directly from the juice of flesh after the separa- tion of kreatine. The salt was dissolved in water, precipitated by 'nitrate of silver, the precipitate well washed, and the potash in the filtered liquor determined in the form of nitrate. 0-4484 gm. of inosinate of potash lost, when heated to 212, 0-0987 gm. of water = 22'02 p. c. 0-3495 gm. of the anhydrous salt yielded 0*156 gm. of nitrate of potash. The calculated composition of the anhydrous salt in 100 parts is Found. 1 eq. Inosinic acid 174 78-7 79-27 1 eq. Potash 47-2 21*3 20-73 1 eq. Inosinate of potash 221-2 100-0 100-00 G 82 INOSINATES. The loss of weight at 212 indicates the presence of 7 eqs. of water of crystallisation = 22'5 per cent. inosinate . Inosinate of Soda. This salt crystallises in slender needles, of silky lustre, and is extremely soluble in water, but insoluble in alcohol. inosinate Inosinate of Baryta. This salt dissolves sparingly in cold, more easily in hot water, and is insoluble in alcohol. 1000 parts of water at 60 dissolve 2*5 parts of inosinate of baryta. When acted on by hot water, it exhibits a peculiarity similar to what is observed in phosphosinate of baryta. If a solu- tion, saturated at from 140 to 158, is heated to boiling, a part of the salt is deposited in the form of a resinous mass ; again, while water at 158 dis- solves a certain amount of the salt, the same quantity of boiling water always leaves a part undissolved, and this residue, by long boiling, undergoes a change, by which it loses its solubility even in water at the lower temperature above mentioned. The crystals of inosinate of baryta are longish four-sided scales of pearly lustre, which, when dry, have the aspect of polished silver. At 212 the crystals lose water, becoming dull and opaque ; in dry air they readily effloresce. 0*555 gm. of the crystallised salt lost, when heated to 212, 0-1059 gm. of water. 1-060 gm. lost, at 212, 0-2020 gm. of water. This gives for 100 parts of salt 19'07 of water. If the inosinate of baryta, like the inosinate of INOSINATES. 83 potash, contained 7 eqs. of water, it would have lost 20 p. c. of water. Inosinate of Copper. This salt, when dried, forms inosinate of copper. a light blue amorphous powder. It is, in the com- mon sense of the term, insoluble in water, which only dissolves so much of it, that ferrocyanide of potassium causes a faint redness, such as salts of copper exhibit when diluted with 500,000 parts of water. It is insoluble in acetic acid, easily soluble with a blue colour in ammonia. Inosinate of Silver. The gelatinous precipitate, inosinate formed by soluble inosinates in salts of silver, is somewhat soluble in pure water, but less so in water containing nitrate of silver. It is not blackened by light, or only to a very trifling extent. The inosinate of silver obtained in the analysis of the potash salt (see p. 81), was decomposed by sulphuretted hydrogen, and the sulphuret of silver thus obtained converted into chloride of silver. 0*3495 gm. of the anhydrous inosinate of potash yielded, in this way, 0-216 gm. of chloride of silver, corresponding to 49*99 parts of oxide of silver, from 100 parts of the potash salt. If the inosinate of silver be proportional in com- position to the inosinate of potash, 100 parts of the latter salt ought to yield 51*02 parts of oxide of silver. The experiment gave, as we have seen, 50 parts of oxide of silver. This difference is considerable ; but when so many operations must be performed with one and the G2 84 INOSINIC ACID same portion of substance, errors of this kind are unavoidable. I am quite aware how imperfect is the investigation of inosinic acid, and of its salts, which I have been able to make ; but flesh contains only a very small quantity of this substance ; and of that which I obtained, a great part was necessa- rily consumed in ascertaining its nature and pro- perties. inosinic Inosinic acid appears, from its composition, to be- habiyY"" long to the coupled acids. Considered as hydrate, acku e it contains the elements of acetic acid, oxalic acid, and urea : 1 eq. anhydrous Acetic acid C 4 H 3 O 3 2 eqs. anhydrous Oxalic acid C 4 O 6 1 eq. Urea C 2 N 2 H 4 O 2 1 eq. hydrated Inosinic acid C 10 N 2 H 7 O n When the acid is heated with hyperoxide of lead, with the addition of diluted sulphuric acid, the oxide loses its brown colour and becomes white, and the filtered liquid, when deprived of the excess of sulphuric acid, deposits on evaporation needle- shaped crystals. When mixed, in the concentrated state, with nitric acid, no precipitate occurs, but there are obtained by evaporation small colourless granu- lar crystals, which I could not further examine, on account of the smallness of the quantity of inosinic acid which I was able to devote to this experiment. Effect of The temperature at which the solution of the tu e P on a the juice of flesh is evaporated, has a great, influence KREATININE IN MUSCLE. 85 on the preparation of the salts of inosinic acid. In preparation ofinosi- many instances, when the temperature had never ex- nates from ceeded 212, I have obtained no trace of inosinate flesh!" of potash or baryta ; while fluid, derived from the flesh of the same animal, yielded tolerably large quantities, when during the evaporation a strong- current of air was made to pass over the surface of the liquid, by which means its temperature was kept as low as from 122 to 140. Kreatinine, as a Constituent of Muscle. When the juice of flesh, from which the inosi- Kreatinine nates have been precipitated by alcohol, is mixed j^Vf with an additional quantity of alcohol, it separates, after about five times its volume of alcohol have been added, into two layers, of which one, a thick syrupy, of a brownish-yellow colour, amounting to l-20th of the bulk of the other, falls to the bottom of the vessel. If these liquids are mixed by agita- tion, they again separate on standing. In the heavy viscid portion, at a temperature of its extrac- tion. 23, there are soon formed a number of transparent colourless four-sided prisms, which are pure chloride of potassium. They melt when heated, without blackening ; their aqueous solution precipitated nitrate of silver, and gave, with bichloride of pla- tinum, a yellow precipitate ; while the mother liquid, when mixed with alcohol, contained no traces of the double chloride of platinum and sodium. . If the lighter fluid be poured off from the heavy 86 KREATININE IN THE viscid one, and the latter mixed with its own volume of ordinary ether, it becomes milky, and on stand- ing a new separation takes place. On the bottom of the vessel there collects an amber-yellow viscid liquid, from which the super- natant lighter ethereal liquid can be easily separated by decaiitation. The heavier consists almost en- tirely of lactate of potash ; the lighter contains also a certain quantity of that salt, but the chief ingre- dient of it is an organic base, which in properties and composition has been found to be identical with kreatinine. When the ether and alcohol are distilled off from this lighter fluid, and the residue evaporated to the consistence of a thin syrup, it forms, on cooling, a semi-solid mass of slender foliated crystals, which, by the addition of alcohol, may be separated from the mother liquid. When these crystals are washed with a little alcohol, dried, and dissolved in boiling alcohol, the solution deposits, on cooling, crystals possessing the form and properties of kreatine. At 212 they become opaque and dull, and lose twelve per cent, of water. The mother liquid, by gentle evaporation, yields yellowish four-sided tables. By means of a little blood-charcoal and hydrated oxide of lead, they are easily rendered colourless ; their aqueous solution is strongly alkaline, and causes white crystalline precipitates in solutions of nitrate of silver, corrosive sublimate, and chloride of zinc. When mixed with hydrochloric acid and bichloride ANIMAL ORGANISM. 87 of platinum, yellow crystals are obtained, of the form and properties of the double chloride of plati- num and kreatinine. Of this platinum salt, 3*3728 gm. yielded on igni- tion 0*1153 gm. of platinum = 30*92 p. c. This is the same per-centage of platinum as in the double chloride of platinum and kreatinine. A portion of the same salt, burned with oxide of copper, yielded a gaseous mixture, containing for 3 volumes of nitrogen 8 volumes of carbonic acid.* o This is the same proportion as in kreatinine. 0*1513 gm. of the dried crystals of kreatinine, Analysis of prepared directly from flesh, yielded 0*2316 gm. of from the carbonic acid, and 0*0865 gm. of water. flesh. Hence this substance contains, in 100 parts Kreatinine Kreatinine from Flesh, from Kreatine. Carbon 41'7 42'54 Nitrogen Hydrogen 6'23 6'38 Oxygen These results leave no doubt as to the nature of this substance, and the occurrence of kreatinine in the organism. The objection, that the kreatinine might have been formed by the action of the free N. C O,. * The 2nd tube yielded 60 156 3rd 66 176 4th 79 211 205 543 N : C = 3 : 8. LACTIC ACID IN THE acid in the juice of flesh on the kreatine, during the short heating necessary to coagulate the albumen, is at once destroyed by the occurrence of kreatinine in neutralised urine, and also by the fact that kreatine may be dissolved and boiled for a long time in mine- ral acids of much greater concentration than the acid of the juice of flesh possesses, without suffering the slightest change, simple pro- Now that the nature of this substance, which I cess for ex- tracting at first took for a peculiar base, different from krea- kreatinine from flesh, tine, is known, it is no longer necessary to employ the circuitous methods which I was compelled to adopt, in order to prevent all foreign chemical action during its preparation. When the mother liquid which has deposited the inosinates is evaporated to dryness in the water-bath, and boiled with alcohol, all the kreatinine is dissolved, and when chloride of zinc is added to the solution, Pettenkofer's compound is deposited either at once or after some hours, as a crystalline deposit, from which, when acted on by hydrated oxide of lead, pure kreatinine is easily obtained. Lactic Acid. Lactic acid When the liquid, from which the inosinates have tuent C of Stl " been deposited, is evaporated in the water-bath, and flesh * the residue acted on by alcohol, all the lactates are dissolved. If the alcoholic solution be separated from the syrupy viscid liquid which is insoluble in it, and the alcohol distilled off, there is left a yellow syrup which, in the course of 8 or 10 days, forms a JUICE OF FLESH. 89 soft semi-solid crystalline mass. The crystals which form in it consist of kreatine, and of the potash salt of a nitrogenised acid, differing in properties from inosinic acid ; they are contained in a mother liquid, the chief ingredient of which is uncrystallisable lac- tate of potash. To prepare lactic acid from this mass, it is mixed with its own volume of diluted sulphuric acid (made with 1 vol. of oil of vitriol and 2 vol. of water), or with a solution of oxalic acid of equal strength. Of the latter, so much is added as to produce a crystal- line deposit, and, in either case, 3 or 4 times its bulk of alcohol is added to the mixture. By the addition of alcohol, the sulphate or oxalate and purifi. of potash is precipitated, while the lactic acid remains in solution. This solution is mixed with ether till no further turbidity is produced, the liquid is filtered from the deposit, the ether and alcohol are distilled off, and the residue is concentrated in the water- bath to the consistence of syrup. This syrup is again acted on by a mixture of alcohol and ether, half its volume of alcohol being first added, and then 5 times its volume of ether, by which means a nearly pure solution of lactic acid in ether is obtained. The ether is then distilled off and the residue mixed with milk of lime, till it acquires a strong alkaline reaction. The liquid is filtered, and the solution of lactate of lime is left in a warm place, where it soon forms a mass of crystals, which are in themselves colourless, but appear yellow from the adhering 90 LACTATES OCCUR IN mother liquor. The mass is diluted with alcohol, and thrown on a filter, where it is washed by cau- tiously adding cold alcohol so as to displace the mother liquor, till the crystals appear quite white. In order to separate any gypsum that may be present, they are now dissolved in alcohol of 60 per cent., the solution is filtered, treated, if coloured, with blood-charcoal, and evaporated, when it readily yields perfectly pure lactate of lime. Modifica- From every sort of flesh, except that of fishes, the process lactate of lime may be obtained by this process ; but for fish it is necessary to modify it. The liquid, for example, obtained from the flesh of the pike, is evaporated to a syrup, and mixed with an aqueous solution of tannic acid, which causes a thick yellowish white precipitate, softening like pitch when heated. The filtered liquid is concentrated, and treated as above directed with sulphuric or oxalic acid, and at last there is obtained,, in the ethereal solution, a mixture of gallic acid (formed by the oxidation of tannic acid) and lactic acid, from which, when the alcohol is expelled, the gallic acid partly crystallises. Without separating these crystals, the acid mixture is saturated with milk of lime, the solution is filtered from the dark brown (nearly black) residue, treated with blood-charcoal, and concentrated, when after a time it yields snow-white crystals of lactate of lime. i When the lime is precipitated from the solution of the pure lactate by sulphuric acid, the filtered liquid evaporated in the water-bath, and the residue THE JUICE OF FLESH. 91 acted on by ether, pure lactic acid is dissolved, and from this any other lactate may be easily pre- pared. 1*276 gm. of lactate of lime lost, when heated to Analysis of 212, 0-323 gm. of water = 25*3 per cent. JJlSpJ^ 1-4735 gm. of lactate of lime lost, when heated fromflesh - to 212, 0-3805 gm. of water = 25-8 per cent. Gm. Gm. p.c. of lime. 0-4900 of lactate of lime (fowl) yielded 0-2195 of carbonate of lime = 25-53 Lactate of 0-4870 (horse) 0-2245 = 25-84 lime. 0-5377 (fox) 0-2452 = 25-54 0-1805 (pike) 0-0830 =25-74 Mean proportion of lime in 100 parts of the salt = 25-65 Hence, lactate of lime contains, in 100 parts Calculated. Found. 1 eq. Lactic acid.. 81 74-32 j jj jjj jy 1 Formula of 74-47 74-19 74-46 74-26 *f y " 1 eq. Lime 28 25-68 25-53 25-81 25-54 25-74 1 eq. Lactate of lime ... 109 100-00 100-00 100-00 100-00 100-00 The crystallised lactate of lime contains Calculated. Found. 1 eq. Lactate of lime 109 75-18 74'7 74'2 a ndofthe 4 eqs. Water 36 24'82 25'3 25'8 Crystallised 1 eq. crystallised Lactate of lime 145 lOO'OO lOO'O lOO'O 0*274 gin. of anhydrous lactate of lime (ox) yielded by combustion with chromate of lead, 0*3335 gm. of carbonic acid, and 0'1152 gm. of water. 0-6420 gm. of anhydrous lactate of lime (fox) yielded 0*7660 gm. of carbonic acid, and 0'274 gm, of water. 92 ANALYSIS OF THE LACTATES The anhydrous lactate of lime therefore contains Calculated. Found. Composi- 6 eqs. Carbon 36 33'02 33-11 32'54 tlteof laC " 5 eqs. Hydrogen 5 4'59 4'66 4'70 lime; 5 eqs. Oxygen 40 36'71 36'58 37'11 1 eq. Lime 28 25'68 25'65 25'65 1 eq. anhydrous Lactate of lime 109 lOO'OO lOO'OO lOO'OO of lactate of The lactate of zinc, prepared from flesh, was also zinc. analysed. Gm. Gm. p.c. 0-499 of lactate of zinc, when heated to 212, lost 0-068 of water = 13'6 1-3295 0-1775 = 13-3 Mean loss 13*45 0*564 gm. of crystallised lactate of zinc left, when ignited, 0*1645 gm. of oxide of zinc = 29*16 per cent. 0*3153 gm. of anhydrous lactate of zinc left, when ignited, 0*1052 gm. of oxide of zinc = 33*31 per cent. 0*5690 gm. of the anhydrous lactate yielded, by combustion, 0*6125 gm. of carbonic acid, and 0*213 gm. of water. 0*2260 gm. of the anhydrous lactate yielded, by combustion, 0*244 gm. of carbonic acid, and 0*0838 gm. of water, its formula Hence, the crystallised lactate of zinc contains* * According to the investigations of Engelhard and Maddrell, lactate of lime, prepared by Fremy's process, contains 5 eqs. (= 29 p. c.) and the lactate of zinc 3 eqs. (= 18 p. c.) of water of crystallisation. It is possible, that this variation in the 1 eq. Lactic acid 1 eq. Oxide of zii 2 eq" Water PREPARED FROM FLESH C 81 Calculated. 58-07 29-03 12-90 93 Found. 57-44 29-16 13-40 in the cry: tab; * nc 40-5 18 1 eq. crystallised Lactate of zinc 139 '5 100-00 100-00 The ultimate analysis of the anhydrous lactate of in the an. hydrous state. zinc gives 36 29-63 29-35 29-44 5 eqs. Hydrogen 5 4-11 4-16 4-12 5 eos Oxysren 40 32-93 33-18 33-13 1 eq Oxide of zinc 40'5 33-33 33-31 33-31 leq. anhydrous Lactate of zinc 121 -5 lOO'OO 100*00 lOO'OO From the preceding analysis it evidently appears The non. . . ' . azotised that the non-nitrogemsed acid occurring in 4the acid of flesh animal organism is identical with the acid formed ac id. in milk when it becomes sour, and into which sugar of milk, starch, grape sugar, and cane sugar are converted by contact with animal substances in a state of decomposition.* The inorganic Constituents of the Juices of Flesh. Chevreul has already directed attention to the inorganic const! - very large quantity of inorganic substances contained tuents of . ,1 . . P i < T i .,1 the juice of in the juice of beef. In his experiments they flesh. amount of water in these two salts depends on this, that the lactates from flesh were crystallised by slow evaporation, and not by cooling. * From the most recent researches of Engelhard and Maddrell, lactic acid appears to be a bibasic acid. It forms an acid salt with baryta, and its formula must consequently be doubled. 94 INORGANIC CONSTITUENTS amounted to rather more than a fourth part of the weight of the matters dissolved in the soup when the flesh is boiled with water. Of the saline mass which he obtained by drying up and incinerating the solu- tion, 81 per cent, were found soluble in water, and the insoluble residue of 19 per cent, consisted of 5 '77 of phosphate of lime and 13*23 of magnesia. It is evident that alkaline salts are the preponde- salts pre- ponderate rating inorganic constituents of the juice of flesh, and that phosphate of lime is in the smallest pro- portion compared to those salts and to the mag nesia. importance Now, since we may assume with a degree of pro- of the inor- ,,.-,., ganiccon- babihty almost amounting to certainty, that, in so perfect a machine as the animal organism, every part has its significance, I have thought it of im- portance to make some experiments on the nature of the mineral acids and alkaline bases occurring in the juice of flesh, and their mutual relations, experi- ments which, however imperfect, may still serve as points of departure for future researches. The organised constituents of the body have been derived from unorganised matters, and return to the unorganised state ; and it is especially with the un- organised substances that our researches must begin. If now it can be demonstrated by investigation that certain inorganic constituents occur in the flesh of all animals, and are never absent therefrom, it will follow that they are essential to the function of the muscles, those most complex parts of the organism ; OF THE JUICE OF FLESH. 95 while, on the other hand, a variation in their relative proportions enables us to infer a corresponding varia- tion in some vital action. When the iuice of flesh (extracted as formerly The ash of J * the juice of described, and therefore diluted with water) is meat con- evaporated, even without the addition of baryta, it alkaline phosphates acquires at last, even when the temperature never and chio- exceeds 112, a brown colour, and a taste of roast meat, and leaves when ignited an ash, which may be burned white, although with some difficulty. This ash dissolves almost entirely in water, and in this solution acids occasion no effervescence ; the ash, therefore, contains no alkaline carbonates. A more minute examination shows that it consists only of alkaline phosphates and chlorides. The precipitate formed by baryta in the iuice of No sui- J . . .1 phates are flesh in many cases dissolves entirely in diluted present. nitric acid ; and in those cases in which a residue of sulphate of baryta is left, its quantity is so trifling that, for example, in the entire flesh of a fowl or of a fox its weight cannot be ascertained. Sulphates or sulphuric acid are therefore not present in the juice of flesh, a fact already ascertained by Ber- zelius. The soluble salts obtained from the ash of the Th e differ- ent forms juice of flesh contain the different modifications of of phos- phoric acid. phosphoric acid, which are easily distinguished by their action on nitrate of silver. It is well known that common or tribasic phos- phoric acid forms three different salts with the 96 CHARACTERS OF THE DIFFERENT alkalies ; two of these, in their aqueous solution, have an alkaline, the third has an acid, reaction. Characters When a salt of phosphoric acid with 3 atoms of f er ent 1 fixed base, which is strongly alkaline, is mixed with tribasic neutral nitrate of silver, a yellow precipitate is P hates formed, the alkaline reaction disappears, and the mixture, after precipitation, if a slight excess of the nitrate of silver be present, is perfectly neutral to test-paper. The salts of tribasic phosphoric acid with 2 atoms of fixed base have also an alkaline reaction. They give with neutral nitrate of silver the same yellow precipitate, and the mixture, after precipitation, is neither alkaline nor neutral, but acid. When these latter salts are ignited, they are converted into pyrophosphates (bibasic phosphates), which, when dissolved in water, exhibit an alkaline reaction, and give with neutral nitrate of silver a white precipitate. After precipitation, the mixture is neutral. The salts of tribasic phosphoric acid with 1 atom of fixed base have a strong acid reaction. With neutral nitrate of silver they give the yellow precipi- tate formerly mentioned, while the mixture retains its acid reaction. When ignited, these latter salts pass into meta- phosphates (monobasic phosphates), of which the metaphosphate of potash is not soluble in water. Metaphosphate of soda dissolves readily in water, and gives with nitrate of silver a white precipitate, MODIFICATIONS OF PHOSPHATES. 97 which again dissolves in an excess of the precipi- tant. If we compare with the characters just described Characters those of the ash of the juice of flesh, we observe of the juice the following facts. The ashes of the juice of flesh, in the case of the ox, horse, fox, and roe-deer, give with water a strongly alkaline solution, which is pre- cipitated, first white, then yellow, by neutral nitrate of silver; and the mixture, after complete precipi- tation, is perfectly neutral. This proves that the they con- ashes contain salts of phosphoric acid, with 2 atoms phosphates (pyrophosphates), and with 3 atoms (tribasic phos- phosphates, phates) of fixed alkaline base. If these ashes are mixed with nitric acid, dried up, and again ignited, by which means the chlorine of the alkaline chlorides is expelled, and the metals added to the phosphates in the form of oxides, the proportion between the white and the yellow preci- pitate with nitrate of silver is altered, the quantity of the yellow precipitate being increased ; but the two colours of the precipitate are constantly ob- served. The ashes of the juice of the flesh of fowl give The ashes of the juice a different result. The aqueous solution precipitates of fowl con- nitrate of silver pure white ; the ashes, therefore, contain alkaline pyrophosphates ; and when they are acted on by nitric acid and again ignited, the solu- ble portion still precipitates nitrate of silver only white, although an additional quantity of alkali is thus added to the phosphate originally present. H 98 ACIDS AND ALKALIES tain pyro- From this it follows, that the juice of the flesh of and meta- fowl must contain a certain though small quantity of alkaline phosphate with 1 atom of fixed base (metaphosphate), since, otherwise, after the action of nitric acid on the ashes, a certain quantity of phosphate with 3 atoms of fixed base (tribasic phos- phate) must have been produced, and thereby a yellow precipitate must have been formed, to a cor- responding extent, in the nitrate of silver. Proportion The whole amount of alkalies, therefore, present tot^ephos- in the juice of the flesh of the ox, horse, fox, and 3ld ' roe-deer, is not sufficient to convert the phosphoric acid of the juice entirely into the so-called neutral salt, that is the salt with 3 atoms of fixed base. In the fowl, the whole of the alkali is not even suffi- cient to convert the phosphoric acid entirely into the salt with 2 atoms of fixed base. I have mentioned in a preceding part of this memoir, that the juice of flesh, even before all the phosphoric acid has been precipitated by baryta, at a period, therefore, when it can contain no baryta dissolved, acquires an alkaline reaction. The organic From this it is plain, that the organic acids pre- Ju!ceare the sent in the juice, the lactic and inosinic acids, &c., dent 1 *?" taken together, are not in sufficient quantity to form neutral salts with the alkalies contained in it, potash and kreatinine ; and this necessarily implies that the acid reaction of the juice of flesh is caused by the presence of acid salts of the alkalies with the three acids phosphoric, lactic, and inosinic acids. Inosi- IN THE JUICE OF FLESH. 99 nic acid constitutes too small a part of the juice to allow us to ascribe to it a perceptible share in pro- ducing the acid quality of that fluid ; and this aci- The acidity of the juice dity depends, therefore, on the presence of acid depends on alkaline lactate and acid alkaline phosphate (phos- sence of phate with one atom of alkali) ; or, in other words, a^d phos- of neutral alkaline lactate and phosphate, along atidT with free lactic and phosphoric acids. It is obvious, that these two acids are shared between the bases present, and that the amount of free acid present must stand in a definite relation to the quantity of the bases. Between the two acids, so far as they are uncom- Equffi- bined, an equilibrium is established ; the quantities tween these of the free acids are proportional to their affinity or power of combination. If we suppose the quantity of one of these free acids to be by any means increased in the juice of flesh, that portion of the other, which is free, must in like manner increase ; and if, by any means, the amount of the one free acid be diminished, the free portion of the .other must diminish in the same proportion, so that a new equilibrium may be estab- lished between the free portions of both. If, for example, a portion of phosphoric acid be added to that present in the juice, a part of this must seize on a part of the alkali of the alkaline lactate ; thus a new quantity of acid phosphate of the alkali will be formed, and a corresponding amount of lactic acid set free. Exactly in the same way must a H2 100 CHANGES OF THE BLOOD DURING DIGESTION. corresponding quantity of phosphoric acid be set free, when the amount of lactic acid present is in any way increased. Now, since the quantity of phosphoric acid in the juice is sufficient to neutralise all the alkali present, while the organic acids are present in smaller pro- portion and do not suffice to form neutral salts with the alkali, it follows that the removal of lactic acid would give rise to the production of neutral phos- phates, and the removal of phosphoric acid would cause the formation of neutral lactates, along with free alkali. When The salt of phosphoric acid, which is formed when organic all organic acids are removed from the juice of flesh, phosphoric although neutral in composition, has an alkaline removed, reaction ; and when all the phosphoric acid is removed, there are left salts of organic acids, which, from the presence of free alkali, also possess an alkaline reaction. Expiana- The preceding considerations naturally lead to some pro- the explanation of some processes in the animal organism. If the stomach obtain from the blood the same acids, which we have found to exist in the juice of flesh, the blood must possess, during digestion, a stronger alkaline quality than it has in the normal state ; and consequently, if the blood is to preserve its normal condition, it must either obtain from the muscles a supply of acid, exactly equal to that which has passed into the stomach, or the excess of alkali must be conveyed to the muscles, or secreted THE FUNCTION OF LACTIC ACID. 101 by the kidneys. If the urine of the animal were acid before digestion, it must, on the latter suppo- sition, become, during that process, transiently neu* tral or alkaline ; if it contained a certain quantity of free alkali, that must be increased. The function of the kidneys, as has long been known, consists in the preservation of an equilibrium in the quality of the contents of the blood ; and this includes the removal of products of the change of matter, and of all such substances as affect the normal quality of the blood. In this point of view What P ur- the solution of the question, " What purposes does served by ! . , , , . f i . the lactic lactic acid serve in the organism { is of peculiar acid ? importance. On this point I have made some experiments, which may perhaps assist us in ap- proaching nearer to the solution. I have, in the first place, repeatedly endeavoured Lactic acid . does not to detect the presence of lactic acid in fresh urine, occur in , T- T -i healthy possessing the usual acid reaction. But I have not urine. been fortunate enough, with the aid of the same process by means of which I succeeded in demon- strating its presence in the juice of flesh, to detect even a trace of lactic acid in the urine of healthy young men. The urine was evaporated in the water-bath to the consistence of syrup, mixed with diluted sulphuric acid, and the acids thus set free taken up by alcohol. The alcoholic solution was evaporated in the water-bath to a thin syrup, to which half its bulk of alcohol and then ether were added, until no more turbidity ensued. If lactic 102 URINE CONTAINS NO LACTIC ACID. acid were present, it must have been dissolved in this liquid, which evidently contained much hydrochloric acid. The ether was removed by evaporation, the residue diluted with water, and acted on, when cold, with an excess of oxide of silver. All the hydrochloric acid was in this way separated as chloride of silver ; had lactic acid been present, the very soluble lactate of silver must have been formed ; but no oxide of silver remained in the filtered solution. The addition of milk of lime precipitated no oxide of silver, and the solution thus neutralised gave on evaporation a small quantity of very pure urea, but no lactate of lime. Putrid urine, treated in the same way, yielded a little acetate of lime in slender needles, but in nt> instance lactate of lime. The urine of healthy men, which has an acid reaction, contains, therefore, no lactic acid, and no substance from which lactic acid can be formed during the putrefaction of urine.* it cannot With respect to the presence of lactic acid in in the urine alkaline urine, the following experiment is suffi- ciently decisive. Three persons, among whom were my two assistants, took a quantity of lactate of potash sufficient to have yielded an ounce of .^x* The absence of lactic acid in the urine which I examined, does not exclude the opinion, that in certain conditions lactic acid may occur in the urine, as occurs in regard to other consti- tuents of the body, which are not found in the urine of healthy persons, while they may be detected in that fluid in certain pa- thological states. LACTIC ACID SUPPORTS RESPIRATION. 103 lactate of zinc. All the urine for the two sub- sequent hours was collected. In each case the urine before the experiment had an acid reaction ; that which was passed immediately after taking the lactate was strongly alkaline, and the potash was easily detected in it, the quantity of that base present exceeding that in ordinary urine. But it was impossible to detect the lactic acid in this urine ; it had entirely disappeared during its pas- sage through the blood. From this it plainly appears, that the lactic acid The lactic acid is cou- m the organism is employed to support the respira- sumed in respiration. tory process, and the function performed by sugar, starch, and in general all those substances which, in contact with animal matter are convertible into lactic Function of acid, ceases to be an hypothesis. These substances is no longer are converted in the blood into lactates, which are destroyed as fast as they are produced, and which only accumulate where the supply of oxygen is less, or where some other attraction is opposed to the agency of that element. When we consider that the urine of graminivorous animals contains a large quantity of free alkali, which is secreted from the blood ; that, consequently, in the blood a current of dissolved alkalies is carried through the whole mass of the body, and especially through the substance of the muscles, while the fluid which is in contact with the external part of the blood-vessels and lympha- tics (the juice of flesh) retains an acid reaction, we Some cause perceive that a cause must necessarily be in action mustpre- 104 POTASH ABOUNDS IN FLESH; vent the re- at these points, which prevents the removal of the the free free acids, or, if they are removed, reproduces them acids in f . muscles. at each moment or time. The blood-vessels and lymphatics contain an alka- line fluid, while the surrounding fluid, that of the flesh, is acid; the tissue of which the vessels are com- posed is permeable for the one or the other of these The condi- fluids. Here then are two conditions favourable to electrical" 1 the production of an electrical current, and it is far from improbable, that such a current takes a certain share in the vital processes, although its action be not always indicated by proper electrical effects.* Potash pre- I have already mentioned, that the juice of flesh, Fn thejuice in all animals, is particularly rich in potash, and that of flesh. .^ con t ams r^ chloride of potassium, with only traces of chloride of sodium. Now, as every con- stant peculiarity in the form or in the composition of any part of the body has a significance of its own, this fact, namely, the predominance of salts of * Professor H. Buff has, at my request, constructed a pile, consisting of discs of pasteboard moistened with blood, of mus- cular substance (flesh), and of brain. This arrangement caused a very powerful deviation of the needle of the Galvanometer, indi- cating a current in the direction from the blood to the muscle. When water was substituted for the brain, the action was much weaker. The current arising from contact of the blood alone with the platinum was, in this case, in the direction oppo- site to that of the current just mentioned. The electrician will find nothing surprising in this, since the blood has an alkaline, the flesh an acid, reaction, while the brain has a scarcely percep- tible degree of alkalinity. SODA IN THE BLOOD. 105 potash and of chloride of potassium, in the juices of flesh, appears to me to be so much the more worthy of attention, that, in the blood, only proportionally small quantities of the salts of potash, and prepon- Soda pre- ponderates derating quantities of the salts of soda, and of com- in the blood. mon salt, are present. To give a specific direction to our views on the Relative subject of these differences, I have thought it ad- of potash .1.1,1 and soda in visable to make some experiments, in which the flesh and relative proportions of the compounds of sodium and potassium in the blood, and in the juice of the flesh, was determined comparatively in different animals. In these determinations the phosphoric acid was Method precipitated from the fluid of flesh by baryta, the filtered liquid evaporated to dryness, and the residue incinerated. The ashes, thus obtained, are very fusible and of peculiar character, consisting almost entirely of cyanate of potash and cyanide of potas- sium, exactly as in the ashes of an alkaline urate. When these ashes are dissolved in hydrochloric acid, effervescence ensues, as with a carbonate, from the decomposition of the cyanic acid ; a certain amount of sal ammoniac is formed, and hydrocyanic is abundantly disengaged. If bichloride of plati- num be now added, to separate the potash from the soda, the precipitate which is formed contains ammo- nia-chloride of platinum, by which the determina- tion of the potash is rendered inaccurate. It is therefore necessary, before adding the bichloride of 106 PROPORTIONS OF POTASH AND SODA platinum, to evaporate the solution of the ashes in hydrochloric acid to dryness, to ignite the residue, and thus expel the sal ammoniac. Results In the analyses made by Henneberff of the blood J O of fowls, for which the blood of all the fowls used . in my researches on the juices of their flesh was employed, there were obtained, including the chlo- ride of sodium, for 100 parts of soda, 40'8 parts of t m the Fowl, potash. The juice of the flesh of the same fowls yielded, for 3*723 gms. of double chloride of pla- tinum and potassium, 0*374 gm. of chloride of sodium. Ox Ox-blood gave, for 0*184 gm. of chloride of pla- tinum and potassium, 1*133 gm. of chloride of sodium. The juice of ox-flesh gave, for 1*933 gm. of chlo- ride of platinum and potassium, 0*2536 gm. of chloride of sodium. Horse, Horse-blood gave, for 1*351 gm. of chloride of sodium, 0*341 gm. of chloride of platinum and potassium. The juice of horse-flesh gave, for 4*414 gm. of chloride of platinum and potassium, 0*544 gm. of chloride of sodium. FOX, The juice from the flesh of a fox, killed in the chase, gave, for 1*474 gm. of chloride of platinum and potassium, 0*250 gm. of chloride of sodium. and Pike. The juice from the flesh of the pike gave, for 1*964 gm. of chloride of platinum and potassium, 0*065 gm. of chloride of sodium. IN BLOOD AND IN FLESH. 107 These results, when reduced and tabulated, give Tabular view. Potash in Potash in the Blood. the Flesh. For 100 parts of soda in the Fowl 40'8 384 Ox 5-9 279 Horse 9'5 285 Fox 214 Pike 497 It is hardly necessary to state, that these num- These num- bers only bers only express approximatively the proportions of approxi- potash to soda in the flesh, because it is impossible to obtain the juice of the flesh of the ox, horse, and fowl, free from blood and lymph, fluids which con- tain much soda. Had it been possible to obtain the juice of flesh unmixed with blood and lymph, the pro- The juice of flesh may portion of potash to soda would have come out much possibly contain no higher; so much so, indeed, that the conclusion, soda, that salts of soda form no part of that fluid, is not destitute of probability ; and if, as is supposed, the lymphatic vessels possess the power of taking up the salts of soda which pass from the capillaries into the substance of the muscles, and returning these salts to the larger blood-vessels, the fact just mentioned admits of a very simple explanation. From the great difference of chemical nature The per- and qualities in the fluids circulating in the different the vessels parts of the organism, it follows, that there must HOUS fluids be a very remarkable difference in the permeability different. of the parietes of the vessels for these fluids. Were this permeability in all cases the same, there must have been found as much of the salts of soda and potash in the juice of flesh as in the blood ; but the 108 IMPORTANCE OF CHLORIDE OF SODIUM blood of the ox and the fowl contains nearly a third of its whole saline contents of chloride of sodium, while hardly a trace of this compound occurs in the juice of flesh. Potash pre- The vessels which secrete milk must stand in a ponderates . . in milk. similar relation to the blood-vessels ; for in the milk of the cow, the salts of potash preponderate very greatly over those of soda, and are present also in much larger quantity than in the saline constituents of blood. Accumuia- In some pathological conditions there has been tion of free acids in observed,* at points where bones and muscles meet, bid states^ an accumulation of free lactic and phosphoric acids, which has never been perceived at those points in the normal state. The solution and removal of the phosphate of lime, and therefore the disappearance causing the of the bones, is a consequence of this state. It is disappear- ance of the not improbable that the cause, or one or the causes, of this separation of acid from the substance of the muscle, is this that the vessels, which contain the fluid of the muscles, have undergone a change, whereby they lose the property of retaining within them the acid fluid they contain. importance The constant occurrence of chloride of sodium of sodium and phosphate of soda in the blood, and that of Wood 6 . phosphate of potash and chloride of potassium in the juice of flesh, justifies the assumption that both facts are altogether indispensable for the processes car- ried on in the blood and in the fluid of the muscles. * Schmidt, Annalen der Chemie und Pharmacie, vol. Ixi. p. 329. TO THE FORMATION OF BLOOD. 109 Proceeding on this assumption, the necessity for Use of salt, adding common salt to the food of many animals is easily explained, as well as the share which that salt takes in the formation of blood, and in the respira- tory process. It is a fact, now established by numerous analyses, inland plants that the ashes of plants, growing at a certain dis- tance from the sea, contain no soda, or only traces of that base. The ordinary potashes of inland countries give contain no most convincing proof of this; for they but rarely little chio- contain any carbonate of soda ; and when a com- dium. pound of sodium occurs in them, it is not phosphate or sulphate of soda, but chloride of sodium. Wheat, barley, oats, root-crops, and plants with esculent leaves, in the Odenwald, in Saxony, and in Bavaria, contain only salts of potash, without salts of soda ; and if, in several, soda sometimes occurs, chlorine is also present, and both are in the proportion to form sea salt. In plants growing in maritime countries near the The same sea coast, these proportions are altered. Wheat, maritime pease, and the other leguminous plants, in the contain Netherlands, contain phosphate of potash, and also potash? phosphate of soda, the phosphate of potash, how- ever, always predominating. This is the case even in sea plants, living in a Even sea ,. 1.1 plants con- medium which contains, compared with its amount tain more of soda or sodium, a mere fraction of potash. All soda! sea plants contain much more potash than soda. 110 ACTION OF PHOSPHATE OF POTASH In respect to these two bases, therefore, the food of animals is not in all places of the same quality or composition. Necessity An animal, feeding on plants which contain phos- of sodium phates of other bases, along with some compound of feeding on soda or sodium, produces in its body the phosphate plants. f s d a indispensable to the formation of its blood. But an animal, living inland, obtains in the seeds, herbs, roots, and tubers which it consumes, only salts of potash. It can produce, from the phosphates of lime and magnesia, by decomposition with the salts of potash, only phosphate of potash, the chief inorganic constituent of its flesh ; but no phosphate of soda, which is a compound never absent in its blood. Whence, therefore, does it obtain this phos- phate of soda ? The true answer to this question is Action of given by a study of the action of phosphate of potash of potash 5 on chloride of sodium. Phosphate of potash, with of sodium? ^ atoms of potash (tribasic phosphate of potash, with 2 atoms of fixed base and 1 atom of water) = P O 5 < TT r\ ?> is deliquescent, hardly crystallis- able, and has a very feeble alkaline reaction. When we supersaturate phosphoric acid (tri- basic) with potash, and evaporate to crystallisation, a salt is deposited, which has an acid reaction = P 5 ( Jr 2). There is no salt which loses half [2 H UJ the amount of base it contains so easily as the phos- phate of potash. If phosphoric acid be neutralised ON CHLORIDE OF SODIUM. Ill with potash, and chloride of sodium added to the solution, and the whole left to spontaneous evapo- ration, a phosphate crystallises, which contains both / fNa Ch\ potash and soda (the tribasic salt P 5 < K > I \ I H O)/ while chloride of potassium is found in the mother liquid. It is obvious, that phosphate of potash is decom- posed when in contact with chloride of sodium; part of the potassium combines with the chlorine, while the sodium replaces it in the phosphate, phosphate of soda being produced.* In this way we can understand the formation of phosphate of soda in the body of an animal, which obtains in its food, along with phosphate of potash, or earthy phosphates and salts of potash, no com- pound of soda except chloride of sodium ; and when, in inland countries, the food does 'not contain com- mon salt enough to produce the phosphate of soda necessary for the formation of the blood, then more salt must be added to the food. From the common salt is produced, in this case, by mutual decomposi- * It is evident that the tribasic salt above mentioned, rNaCh P O 5 < K O >may equally well be represented as a double salt, Nax O i f 2 K O composed of phosphate of soda and phosphate of potash. i f 2 }+ po <{ W. G. 112 USES OF THE PHOSPHATE OF SODA tion with phosphate of potash or with earthy phos- phates, the phosphate of soda of the blood. The phos- That phosphate of soda is indispensable to the sodVinthe normal constitution of the blood, and that the pro- cesses which go on in that fluid cannot be replaced by phosphate of potash, seems to me to be an opinion of potash, fully justified by the properties of these two salts. Through the blood, the carbonic acid formed in the body is conveyed out of it, and the alkaline importance quality of the blood has a very decided share in its taining r the property of thus taking up carbonic acid ; as, on the ofTheTikt- other hand, the chemical nature of the compound, biood. of the on whidi the alkaline reaction of the blood depends, exerts the most marked influence on the power of the blood, again to give off the carbonic acid which it had absorbed. Relation of It is known that freshly-drawn blood, by mere carbonic agitation with air^ by passing through it a current acid gas. Q f hydrogen gas, or in the vacuum of the air-pump, gives off carbonic acid. From the experiments of Scheerer, at which 1 had the opportunity of being present, and of others, it is known, moreover, that, for example, the clear serum of ox blood, free from blood corpuscules, absorbs nearly twice its volume of ments of Scheerer. carbonic acid, that is, as much more as the same bulk of water can absorb at the same temperature. The greater absorbing power of the serum is deter- mined by a chemical attraction, by a substance, which has an alkaline reaction. In fact, it is ob- served, that, when this alkaline reaction is destroyed, CONTAINED IN THE BLOOD. 113 when acetic acid is added to the blood saturated with carbonic acid, the excess of carbonic acid is at onee given off. But the same thing happens when this blood is agitated with gases, such as hydrogen } for a long time, and the gases renewed from time to time. Blood, when not saturated with carbonic acid, gives off, in vacuo, nearly 5 p. c. of its volume of that gas ; the addition of acetic acid increases the quantity of the carbonic acid disengaged ; but even under these circumstances not more than half its volume of carbonic acid can be obtained from blood. Had the greater absorptive power of the serum The serum of blood for carbonic acid been dependent on the contains no presence of carbonate of soda, and its conversion into bicarbonate of soda, this would imply that the blood must contain at least its own volume of car- bonic acid in the form of neutral carbonate of soda. If blood contained its own volume of carbonic acid in the form of neutral carbonate, and no free carbonic acid, this blood would absorb exactly twice its volume of carbonic acid (one volume to form bicarbonate, the other to saturate the liquid as it would an equal bulk of water), and the addition of acids which decompose the carbonate of soda, must, in that case, disengage a volume of carbonic acid equal to twice the volume of the blood. The acid would, in fact, disengage three volumes of carbonic acid, one of which is retained by the liquid. In the experiments of Scheerer, serum of blood, which i 114 RELATION OF BLOOD AND SERUM had absorbed twice its volume of carbonic acid, only yielded half as much carbonic acid as ought to have been given off on the above supposition. There was less than one volume of free carbonic acid present in the serum, and the liquid retained, for that reason, a proportionally greater quantity of car- bonic acid.* The au- When 2,000 cubic centimetres of ox-blood, mixed thor's ex- periments with twice their volume of water, are heated to this. boiling, and the coagulum pressed out, we obtain about 2,000 c. c. (l-3rd of the whole liquid) of an alkaline liquid. If the alkaline reaction of this liquid arises from carbonate of soda, these 2,000 c. c. must contain l-3rd of the whole carbonate of soda contained in that volume of blood. When concen- trated to l-3rd by evaporation, this liquid must con- tain exactly as much, if concentrated to l-6th, twice * Annalen der Chemie und Pharmacie, vol. xl. p. 30. I. 60 vols. of serum absorbed 124 vols. of carbonic acid. II. 56 111 116 235 After the addition of 30 cubic centimetres of acetic acid to the first portion, and of 28 c. c. to the second portion of serum, in all after the addition of 58 c. c. of acetic acid, there were disengaged, from 174 vols. of the mixture (116 vols. of serum and 58 vols. of acetic acid) 89 vols. of carbonic acid. Had the blood contained its own volume of carbonic acid in the form of neutral carbonate of soda, it must have given off 177 vols. of carbonic acid; that is, 23558 (the volume which would be retained by the acetic acid). According to these experiments, the actual amount of carbonic acid present in the blood is calculated to be 28 per cent, of its volume. TO CARBONIC ACID GAS. 115 as much, to 1-1 2th, four times as much, and to l-24th, eight times as much, &c. carbonate of soda as an equal volume of blood. Now, I have concentrated this liquid to 1 -500th Highly of its volume, in which state it must, on the suppo- troted*" sition formerly mentioned, contain 166 times as absorbs much carbonate of soda as an equal volume of blood, acid, 0m if that salt were an ingredient of blood. When brought in contact with carbonic acid, this concen- trated liquid absorbed 3 times its own volume ; 20 c. c. absorbed 60 c. c. of carbonic acid. Now it is certain that if this absorptive power had been dependent on the presence of carbonate of soda, the solution, saturated with carbonic acid, must have given off, when mixed with acids, 3 times its original volume of carbonic acid, of which l-3rd would be retained by the liquid. From 20 c. c., therefore, of the concentrated liquid, there should but does have been obtained 40 c. c. of free carbonic acid, off *traoe But this liquid, when acted on by acids, gave off no padded* appreciable trace of carbonic acid gas. According to the observations of Marchand, this liquid is not free from carbonic acid, when it has been mixed with another acid, for by heating it carbonic acid is expelled. But even on the most 7-5 cubic favourable supposition, that is, if we admit that the serum can- liquid is saturated with carbonic acid, it is obvious mor e tha n n that no more carbonate of soda can be contained in gra i n S f it than corresponds to the volume of carbonic acid of required to saturate the l-166th part of the volume i2 116 THE ABSORBENT POWER OF SERUM of the serum. This amounts, for 1,000 c. c. of serum, to so much soda as is saturated by 6 c. c. of carbonic acid gas = 0*026 gm. of carbonate of soda, or 2-5ths of a grain, butitab- The serum of blood absorbs, therefore, 166 times sorbs at least 166 more carbonic acid than could be absorbed by the times more carbonic very largest proportion of carbonate of soda which acid than this carbo- it can be supposed to contain ; and consequently the carbonate of soda, if it be present at all in the liquor sancjuinis, can have but a most insignificant share in the absorptive power of that fluid for car- bonic acid. This de- As the study of the serum and the analysis of pends on the phos- the ashes of blood prove, the alkaline quality of the soda. blood depends on the presence of phosphate of soda. Indeed, it may well be asked, from what source can carbonate of soda, if we suppose it to be present, be derived, in the blood of a man living on bread and flesh, or of an animal feeding on flesh, since in these kinds of food the alkalies and phosphoric acid are present in the proportion in which they form salts with 2 and with 3 atoms of fixed base ?* * The experiments of Erdmann on the incineration of wheat (Annalen der Chemie und Pharmacie, vol. liv. p. 354) leave no doubt, that the tribasic phosphates (with 3 atoms of fixed base) in these ashes are derived from the action of carbon on the phos- phates with 1 and 2 atoms of fixed base, at a red heat, or from the decomposition of chloride of sodium in contact with these phosphates. In the analyses of Henneberg, where this last cause was avoided, the formation of pyrophosphate of soda proves, that the blood of fowls contains tribasic phosphate of soda with 2 atoms of fixed base (P O 5 , 2 Na O, H O). DEPENDS ON PHOSPHATE OF SODA. 117 There is no known salt, the chemical characters Remark - of which approach more closely to those of the pertiesTf serum of blood, than the phosphate of soda ; there of soda! e is none more fitted for the absorption and entire removal from the organism of carbonic acid. This salt behaves towards carbonic acid exactly as neu- tral carbonate of soda ; its aqueous solution absorbs carbonic acid gas with the same facility, but with it not only this difference, however, that under the influence of but also' the same causes which decompose the neutral car- carbonic' bonate, and the bicarbonate of soda, this solution gre atfaci- gives off the carbonic acid which it has absorbed nty< much more easily, and also more completely, since it does not, like soda, in its conversion from bicar- bonate into neutral carbonate, retain any portion of carbonic acid. When carbonic acid gas is placed in contact with a solution of 1 part of dry phosphate of soda (P0 5 , 2NaO, HO), in 100 parts of water, twice as much carbonic acid is absorbed as an equal volume of water, at the same temperature, can take up.* By simple agitation with air, or by diminution of the atmospheric pressure, 2-3rds of the absorbed carbonic acid are given off at the ordinary tempera- ture; by contact with fresh carbonic acid, these 2-3rds are immediately again absorbed.f * A solution of phosphate of soda, saturated with carbonic acid, may be recommended as one of the pleasantest saline pur- gatives. Ex f A solution of 1 part of dry phosphate of soda, P O s , 2 Na O, ments. 118 IMPORTANCE OF THE PHOSPHATE Uses of the By the spontaneous evaporation in the air of the phosphate of soda in solution of phosphate of soda, saturated with car- blood. bonic acid, the whole of the carbonic acid is given H O, in 100 parts of water, when agitated with pure carbonic acid gas, free from atmospheric air, absorbed : I. II. III. IV. Solution, cubic centimetres 59 38 62 56 Carbonic acid absorbed c. c 104 77 114 112 100 vols. of the solution absorb, therefore 176 203 183 200 Mean amount of gas absorbed by 100 vols. of solution = 190 vols. The water which had been used for the solution was treated in the same way, and absorbed : I. II. III. Water, c. c 104 75 54 Carbonic acid absorbed c. c 98 64 52 100 vols. of water absorb, therefore 95 85 98 Mean amount of gas absorbed by 100 vols. of water = 92 vols. A portion of the solution of phosphate of soda, as above, was saturated with carbonic acid, and then agitated with repeated portions of air, as long as any carbonic acid was expelled. The solution was now placed in contact with pure carbonic acid gas, and absorbed : I. II. III. IV. Solution, c. c 62 67 68 89 Carbonic acid absorbed c. c 88 91 99 116 lOOvols. of solution absorb, therefore... 143 134 145 130 Mean amount absorbed by 100 vols. of solution = 138. A similar solution of phosphate of soda, saturated with car- bonic acid, was deprived, as completely as possible, of that gas, under the receiver of the air-pump, being left for two hours under a pressure of 2'". When again placed in contact with carbonic acid, it absorbed : I. II. III. 74 80 70 Carbonic acid absorbed c. c. ... 99 107 96 100 vols., therefore, absorb ... 120 133 137 Mean amount absorbed by 100 vols. of solution = 130. OF SODA IN THE BLOOD. 119 off, and the phosphate is left, with all its original properties, including its alkaline reaction. When carbonic acid is taken up by the blood, Action of there is established between the phosphoric and car- acid on the bonic acids an equilibrium, similar to that existing in the juice of flesh between the phosphoric and lactic acids. In the same way as these last divide % between them the potash of the juice, so do the carbonic and phosphoric acids divide between them the soda of the blood. There can be no circum- stances more favourable to the separation of one or other of the two acids. If we assume, that the carbonic acid seizes a por- tion of the soda, we may imagine that the phospho- ric acid, previously combined with this portion of base, is expelled from the place it originally occu- pied, and thus set free ; but it does not yet, on that account, separate from the compound. We can say that the carbonic acid is converted into carbonate of soda, only when the free phosphoric acid has been removed, and employed in another quarter ; but in point of fact, this phosphoric acid, thus displaced, is always present, and retains, unimpaired, its power of again combining with the soda. The slightest cause, coming in aid of its affinity, so as to give it the preponderance (and to this category belong all causes which diminish the affinity of carbonic acid for soda), suffices to displace the carbonic acid, and to reproduce the original compound. Agitation with air; the spontaneous evaporation of the water, in 120 PROPORTIONS OF LIME, MAGNESIA, which the compound is dissolved ; the diminution of the atmospheric pressure ; all these causes, which have no effect on neutral carbonate of soda, produce decomposition, and cause the separation of the car- bonic acid, taken up by the phosphate of soda in Theamount the blood. In this manner, the amount of carbo- of carbonic . t acid in the me acid in the blood is kept at a constant value. bloocfis keptuni- If more carbonic acid enter the blood from the body, more phosphoric acid is set free in proportion, and thereby a more easy and complete separation of the carbonic acid in the lungs is secured. If more soda be taken up, then a part of the carbonic acid, which would otherwise have escaped by the lungs and skin, is expelled by the urinary passage in the form of carbonate of soda. influence of It is easy to foresee, that a more exact study of acids, alka- lies, and the influence which alkalies, salts, and mineral acids salts on re- spiration, exert on the respiratory process in the normal state, must lead to the most beautiful and valuable results in regard to their employment in various diseases. The juice It has already been pointed out, that in the juice contains of flesh the amount of phosphate of lime, compared lime. with that of phosphate of magnesia, is very trifling. In fact, the juice of ox-flesh contains so little lime, that the quantity obtained from many pounds of flesh amounted only to a few milligrammes (1 milligramme = l-75th of a grain, nearly) ; but in the juice of the flesh of fowls, the relative proportions of these two bases admitted of more exact determination. The J* uice of fowl>s flesh was precipitated by AND ALKALIES IN FLESH. 121 baryta, the precipitate dissolved in hydrochloric magnesia , . in the juice acid, the baryta separated by sulphuric acid, and offbwi. then the phosphoric acid removed by means of sesqui-chloride of iron and ammonia. The lime and magnesia then remained in solution. There were obtained 0*72 gm. of carbonate of lime, and 0*431 gm. of phosphate of ammonia and magnesia ; or for 10 parts, by weight, of lime, 39 '2 parts of magnesia. The proportion of the phosphoric acid combined Proportion of alkaline with alkalies, to that united with magnesia, in the phosphates. juice of ox-flesh, was determined in the following manner. The precipitate formed by baryta contains all the phosphoric acid, partly combined with baryta (as P 5 , 3 Ba 0), partly with magnesia (as P 5 , 3 Mg 0). This precipitate was decomposed by sul- phuric acid, and the liquid, filtered from the sulphate of baryta, was precipitated by ammonia. In this way the magnesia was thrown down, in the form of the usual double phosphate. The liquid filtered from this precipitate contained the phosphoric acid originally combined with alkalies, and when mixed with sulphate of magnesia yielded a new precipitate of the same double phosphate of ammonia and mag- nesia. The weight of the first precipitate was to that of the second as 0-2782 to 0*974, or as 1 to 3*5. For 2 atoms of phosphoric acid, therefore, combined with magnesia, the juice of ox-flesh contains 7 atoms of phosphoric acid, combined with alkalies, chiefly potash. In another experiment the proportion was found to be as 1 to 3*2. 122 PRACTICAL APPLICATION OF THE RESULTS. SECTION III. Practical Application of the Results of the Foregoing Investigation. Effect of With reference to a future chemistry of alimen- boiling on flesh. tary substances, it appears from these researches, that by the boiling of flesh an essential change in its composition is effected . According to the dura- tion of the boiling, and the amount of water em- ployed, there takes place a more or less perfect sepa- ration of the soluble from the insoluble constituents of flesh. The water in which flesh has been boiled contains soluble alkaline phosphates, lactates, and inosinates, phosphate of magnesia, and only traces of phosphate of lime ; the boiled flesh contains chiefly, with the fibrine, &c., the insoluble inorganic constituents, phosphate of lime and phosphate of magnesia. It is obvious, that if flesh, employed as food, is again to become flesh in the body, if it is to retain the power of reproducing itself in its original con- dition, none of the constituents of raw flesh ought to be withdrawn from it during its preparation for food. If its composition be altered in any way, if one of the constituents which belong essentially to its constitution be removed, a corresponding varia- tion must take place in the power of that piece of flesh to reassume in the living body the original form and quality, on which its properties in the living organism depend. BOILING OF FLESH. 123 It follows from this, that boiled flesh, when eaten Boiled meat . T.-I. . i 7 .yy without the without the soup formed in boiling it (the oouilli soup is without the bouillon) is so much the less adapted for ous. nutrition, the greater the quantity of the water in which it has been boiled, and the longer the dura- tion of the boiling. When finely chopped flesh is extracted with cold cold water water, it loses the whole of the albumen contained the soluble in it. The fibrinous residue, after being well washed with cold water, if boiled with water is flesh ' found to be perfectly tasteless ; it is clear that all the sapid and odorous constituents of flesh exist in the flesh itself in the soluble state, and consequently, when it is boiled, are transferred to the soup. The smell and taste of roasted flesh arise from the so- luble constituents of the juice, which have under- gone a slight change under the influence of the higher temperature. Flesh, which has been ren- importance . 111 f t ^ r dered quite tasteless by boiling with water, acquires constitu- the taste and all the peculiarities of roasted flesh, when it is moistened and warmed with a cold aqueous infusion of raw flesh which has been evaporated till it has acquired a dark brown colour.* * Note by the Editor. The Stock so much used by good cooks, and for preparing which, generally from beef, but often also from mixed flesh, such minute directions are given in books on cookery, is essentially such a concentrated infusion of flesh as that described in the text. It is usually made by long boiling, but this is not indispensable. The addition of stock to any dish not only improves the flavour, but often restores the soluble mat- ter removed in previous operations, such as boiling, &c., and thus renders it much more wholesome and nutritious than it would 124 FLESH COMPLETELY EXTRACTED All sorts of flesh are alike in this respect ; the sapid and odorous constituents are present in the roasted The flavour flesh in solution, or in the soluble state. The liquid and of the which is obtained by lixiviation of different kinds of kind^of flesh with cold water, after it has been heated to boiling, and the albumen thus coagulated, possesses, in all cases, the well-known general flavour of soup ; but each kind, individually, has, besides this, a peculiar taste, which recalls the taste and smell of the different sorts of flesh ; insomuch that, when to boiled beef, for example, the concentrated cold depends on aqueous infusion of roe-deer venison or of fowl matter! 1 is added, and the whole warmed together, the beef cannot then be distinguished by the taste from the venison or the fowl. A slight addition of lactic acid (a very little fresh sauerkraut, for it is height- example), or of chloride of potassium, which is ened by lac- tic acid or an invariable constituent of all infusions of flesh, by chloride . . , . of potas- heightens the piquancy of the flavour of meat ; as siura. otherwise be. A good cook judges of almost every thing by the taste, and we see in the text the explanation of this, since the sapid constituents are among the most valuable parts of the food. We see, also, that in cookery, as in other domestic arts, long experience and observation have led, in many instances, to the most judicious practice. It is the want of a scientific basis, how- ever, for the culinary art, that has given rise to many absurd and hurtful methods of preparing food ; as, for example, the very com- mon English practice of boiling meat or vegetables with a very large quantity of water, which is thrown away, and with it the whole, or nearly the whole, of the soluble matter. The advantage of stewing over boiling depends on the fact, that in the former all the soluble matter is retained in the sauce or juice, which is served with the meat. W. G. BY COLD WATER. 125 on the other hand, an alkaline liquid, or the addi- tion of blood, renders the soup or infusion of meat utterly insipid and mawkish. From all the different kinds of flesh we obtain, The flesh of by lixiviation with cold water, the whole of the contains iit- albumen present in them, in the dissolved state, n^, u The quantity of coagulated albumen, which sepa- rates from the infusion when heated, is very differ- ent in different specimens, and seems to stand in a certain relation to the age of the animal. The flesh of old animals is proportionally poor in albumen, and, on the other hand, it is so much the richer in fibrine. but much From the flesh of an old horse, for example, there was not obtained the tenth part of the quantity of albumen which was furnished by an equal weight of ox-flesh. The muscular fibre, in the natural state, is every- Muscular where surrounded by a liquid containing dissolved albumen. When this is removed, the fibre, in all animals, is of the same quality. The well-washed muscular fibre, when boiled with water, becomes, hard and horny, and this the more the longer it is its tender- boiled. It is obvious, therefore, that the tender- pendson ness of boiled or roasted meat depends on the menofthe quantity of the albumen deposited between the JU1< fibres, and there coagulating ; for the contraction or hardening of the fibrinous fibres is thereby to a certain extent prevented. This quality, tenderness, however, also depends on the duration of the boil- ing ; for the albumen also becomes harder by 126 BEST MODE OF BOILING MEAT. Action of hot water on flesh. Best me-, thod of boiling meat. Tempera- ture re- quired. continued boiling, without, however, assuming a tough consistence. The influence of hot water on the quality of the meat which is boiled with it, and of the soup ob- tained, hardly requires, after what has been said, any further elucidation. If the flesh intended to be eaten be introduced into the boiler, when the water is in a state of brisk ebullition, and if the boiling be kept up for some minutes, then so much cold water added as to reduce the temperature of the water to 165 or 158, and the whole kept at this temperature for some hours, all the conditions are united, which give to the flesh the quality best adapted to its use as food. When it is introduced into the boiling water, the albumen immediately coagulates from the surface inwards, and in this state forms a crust or shell, which no longer permits the external water to pene- trate into the interior of the mass of flesh. But the temperature is gradually transmitted to the interior, and there effects the conversion of the raw flesh into the state of boiled or roasted meat. The flesh retains its juiciness, and is quite as agreeable to the taste as it can be made by roasting ; for the chief part of the sapid constituents of the mass is re- tained, under these circumstances, in the flesh. If we reflect that the albumen of the juice of flesh begins to coagulate at a temperature of 105*5 and that it is completely coagulated at 140 (Ber- zelius), it might be supposed that it would not be UNDERDONE MEAT. 127 necessary, in the cooking of flesh, to expose it to a higher temperature than 140. But, at that tem- perature, the colouring matter of the blood is not yet coagulated ; the flesh, indeed, is eatable, but when it contains blood, it acquires, under these cir- cumstances, a bloody appearance, which it only loses, Underdone when it has acquired, throughout the whole mass, a temperature of 150 to 158. In the interior of a very large piece of flesh, which has been boiled or roasted, we can tell with certainty the temperature attained in the different parts, by the colours which they present. At all those parts which appear bloody, the temperature has not reached 144. In the boiling or roasting of Poultry is sooner done poultry, the flesh or which is white, and contains than beef little blood, the temperature of the inner parts, when the flesh has been well cooked, seldom exceeds 130 or 140. The flesh of poultry or game is therefore sooner dressed (ready, or done as it is called) than flesh which contains much blood, such as beef or mutton. By enveloping small pieces of flesh (as is often Use of a done in the case of small birds, such as quails, or- Sin S tolans, larks, and even partridges) with a covering of lard, the extraction of the sapid constituents from the flesh by its juices, and the evaporation of the water, which causes hardening, are prevented ; and the surface, as well as the subjacent parts, are kept in the tender state, which is otherwise only found in the inner portions of large masses of flesh. 128 GELATINE NOT THE CAUSE HOW meat is to be boiled to soup. Meat from neither mi- digestfbie 0r Gelatine is "ourc^of thestrength The introduction of the piece of raw flesh into water already boiling is the best process for the dressing of the meat, but the most unfavourable for the quality of the soup. If, on the contrary, the piece of raw meat be placed in cold water, and this brought very gradually to the boiling point, there occurs, from the first moment, an interchange be- tween the juices of the flesh and the external water. The soluble and sapid constituents of the flesh are dissolved in the water, and the water penetrates into the interior of the mass, which it extracts more or less completely. The flesh loses, while the soup gains, in sapid matters ; and, by the separation of albumen, which is commonly removed by skimming, as it rises to the surface of the water when coagu- lated, the surface of the meat more particularly loses its tenderness and shortness (as it is called), becoming tough and hard. The thinner the piece of flesh, the more completely does it acquire the last-mentioned qualities ; and if in this state it be eaten without the soup, it not only loses much of its nutritive properties, but also of its digestibility, inasmuch as the juice of the flesh itself, the con- stituents of which are now found in the soup, are thus prevented from taking part in the digestive process in the stomach. The soup, in fact, contains two of the chief constituents of the gastric juice. It has long been customary to ascribe to the gelatinous matter dissolved during boiling, which g iyeg ^ concentrated soup the property of forming OF THE STRENGTH OR FLAVOUR OF SOUP. 129 a jelly, the chief properties or peculiarities of the or flavour soup ; but there cannot be a greater mistake. The simplest experiments prove that the amount of dis- solved gelatine in well-prepared soup is so small, that it cannot come into calculation in explaining its properties. Gelatine is, in itself, quite tasteless, and consequently the taste of the soup cannot be derived from it. In order to determine the amount of gelatinous Experi- matter dissolved in the boiling of flesh under the ascertain most favourable circumstances, finely-chopped meat was exhausted with cold water, pressed as dry as possible, and the residue, fibres and membranes, ofsoup< boiled for five hours with ten times its weight of water, the liquid pressed out from the insoluble matter, and evaporated to dry ness in the water-bath. The soup thus obtained, from beef and veal, was tasteless, or rather had a peculiar mawkish taste, which to most persons was nauseous. That from veal gelatinised when reduced to half, that from beef when reduced to 1-1 6th of its original vo- lume. 3,000 grammes of lixiviated veal (6 Ibs.) yielded, under these circumstances, after five hours' boiling, 47*5 gms. of matter dissolved by the water (gela- tine, &c.). 1,000 gms. of lixiviated beef (2 Ibs.) yielded, in the same way, 6 gms. of gelatine, &c. It appears from these experiments, that the mus- cular fibres and membranes of the calf and ox, in K 130 BEST METHOD OF PREPARING that state in which they present to the dissolving energy of the water the largest surface, and after five hours' boiling, yielded, the former only 1*576 per cent., the latter 0'6 per cent, of soluble mat- ter, of which the gelatine certainly does not con- stitute one-half, since some part or constituent of the fibrin e is also dissolved under these circum- stances. Those constituents of 1,000 gms. or 2 Ibs. of beef, which are soluble in cold water, weighed, when dry, 60 gms., of which 29'5 gms. were al- bumen. Amount of Under the most favourable circumstances, there- fore, we obtain, from 1,000 gms. of beef meat by hot and By Boiling. coldwater - r Coagulated Albumen ... 29'5 Soluble in cold water ... Gelatine 6'0 ^Fibres, Membranes, &c. 164'0 Fat 20 Water . . 750 ri Insoluble in cold water. . . 1 70 < . 1,000 It follows, that boiling water, when allowed to act for five hours on finely-chopped flesh, yet does not dissolve more than the fifth part of the matters soluble in cold water, even after the albumen has been separated by heating the cold infusion ; and that this fifth part, besides, does not consist of pure gelatine, but contains all the products dissolved out of the muscular fibres by long boiling. ' SOUP FROM FLESH. 131 Consequently the efficacy of soup, or decoction of flesh, cannot depend on the gelatine it contains. The flesh of poultry contains, for equal weights, More soiu- J ^ ble matter more of the matters soluble in cold water, and in poultry than in remaining dissolved after the coagulation of the beef, albumen, than beef does. From 1,000 gms of fowl, cold water takes up 80 gms. of soluble matter, of which 47 gms. consist of albumen, and 33 gms. remain dissolved in the liquid when boiled. The characters of flesh described in the preceding The nutri- paragraphs at once suggest the best method of pre- ^pld ingle- paring, in the short space of a few minutes, the strongest and most highly-flavoured soup ; and any f^med i one may convince himself, by the simplest experi- flesh - ments, of the truth of the assertion made by Proust, that those constituents of soup, on which its taste and other properties depend, exist ready formed in the flesh, and are not iu any way products of the operation of boiling. When 1 Ib. of lean beef, free of fat, and sepa- Best me- rated from the bones, in the finely-chopped state in preparing which it is used for beef sausages or mince-meat, soup ' is uniformly mixed with its own weight of cold water, slowly heated to boiling, and the liquid, after boiling briskly for a minute or two, is strained through a towel from the coagulated albumen and the fibrine, now become hard and horny, we obtain an equal weight of the most aromatic soup, of such strength as cannot be, obtained, even by boil- K2 132 EXTRACT OF FLESH, OR ing for hours, from a piece of flesh. When mixed with salt and the other usual additions, by which soup is usually seasoned, and tinged somewhat darker by means of roasted onions or burnt sugar, it forms the very best soup which can in any way be prepared from 1 Ib. of flesh. influence of The influence which the brown colour of this the brown colour of soup, or colour in general, exercises on the taste, m judgment e consequence of the ideas associated with colour in the mind (ideas of strength, concentration, &c.), andflalour. ma y be rendered quite evident by the following experiment. The soup, coloured brown by means of caramel, is declared by all persons to have a much stronger taste than the same soup, when not coloured ; and yet the caramel, in point of fact, does not in any way actually heighten the taste. Extract of If we allow the flesh to boil for a long time with true porta- the water, or if we boil down the soup, it acquires, spontaneously, when concentrated to a certain point, a brownish colour and a delicate flavour of roast meat. If we evaporate it to dryness in the water- bath, or if possible at a still lower temperature, we obtain a dark brown, soft mass, of which half an ounce suffices to convert 1 Ib. of water, with the addition of a little salt, into a strong, well- flavoured soup. Portable The tablets of so-called portable soup prepared in commerce England and France are not to be compared with "uremia- the extract of flesh just mentioned ; for these are not made from flesh, but consist of gelatine, more PORTABLE SOUP. 133 or less pure, only distinguished from bone gelatine by its higher price.* From 32 Ibs. of lean beef, free from bones and fat Beef yields (8 Ibs. dry meat and 24 Ibs. water), there is obtained weight of 8 1 Ib. of true extract of flesh, which, from its neces- beef? sarily high price, can hardly become an article of commerce ; but if the experience of military sur- geons agrees with that of Parmentier, according to whom " The dried extract of flesh, as an article of Extract of " provision in the train of a body of troops, supplies " to severely wounded soldiers a restorative, or " roborant, which, with a little wine, immediately ed " revives their strength, exhausted by great loss of " blood, and enables them to bear the transport to " the nearest hospital," f it appears to me to be a matter of conscience to recommend to the atten- tion of governments the proposal of Parmentier and of Proust. Now that the composition of the extract of flesh Characters of genuine is somewhat more accurately known, it ought to be and of false easy for every well-informed apothecary to distin- meat. guish the genuine from the false. Of the true extract, nearly 80 per cent, is soluble in alcohol of 85 per cent., while the ordinary tablets of portable * Note by the Editor. I have seen some specimens of port- able soup, which, although consisting chiefly of gelatine, yet had a strong flavour of soup, and probably, therefore, contained a certain proportion of extract of flesh. W. G. f See Proust, Annales de Chimie et de Physique. Third .Se- ries, vol. xviii. p. 177. 134 SALTING OF FLESH. soup rarely yield to that menstruum more than 4 or 5 per cent. The presence of kreatine and kreati- nine, the latter of which is instantly detected by the addition of chloride of zinc to the alcoholic solution, as well as the nature of the salts left on incineration, which chiefly consist of soluble phos- phates, furnish sufficient data for judging of the quality of the true extract of flesh. Extract of I consider this extract of flesh as not less valuable command- for the provisioning of ships and fortresses, in order and f for- hlps to preserve the health of the crew or garrison, in those cases where fresh meat and vegetables are wanting, and the people are supported by salt meat. Saitin of -^ * s universally known that in the salting of meat. meat, the flesh is rubbed and sprinkled with dry salt, and that where the salt and meat are in contact, a brine is formed, amounting in bulk to l-3rd of the fluid contained in the raw flesh. The brine I have ascertained that this brine contains the melt con. chief constituents of a concentrated soup or infusion ingredients of meat, and that, therefore, in the process of salting, tract 6 ; CX * ne composition of the flesh is changed, and this, too, in a much greater degree than occurs in boil- ing. In boiling, the highly nutritious albumen remains in the coagulated state in the mass of flesh, but, in salting, the albumen is separated from the flesh; for when the brine from salted meat is heated to boiling, a large quantity of albumen separates as a coagulum. This brine has an acid reaction, and gives with ammonia a copious precipi- EFFECTS OF SALTING. 135 tate of the double phosphate of ammonia and mag- . phates, lac- nesia. It contains also lactic acid, a large quantity tic add, of potash, and kreatine, which, although I could not and separate that body from the large excess of salt, may be safely concluded to be present, from the presence of kreatinine. The brine, when neutralised by lime, gives, after the salt has been crystallised out, a mother liquid, from which, after some time, when alcohol and chloride of zinc are added to it, the double chloride of zinc and kreatinine, so often men- kreatinine. tioned in the former part of this work, is deposited. It is now easy to understand that in the salting of Saitedmeat is deficient meat, when this is pushed so far as to produce the in nutritive quality. brine above mentioned, a number of substances are withdrawn from the flesh, which are essential to its constitution, and that it therefore loses in nutritive quality in proportion to this abstraction. If these substances be not supplied from other quarters, it is obvious that a part of the flesh is converted into an element of respiration certainly not conducive to good health. It is certain, moreover, that the health of a man cannot be permanently sustained by means of salted meat, if the quantity be not greatly in- Causes of creased, inasmuch as it cannot perfectly replace, by the substances it contains, those parts of the body which have been expelled in consequence of the change of matter, nor can it preserve in its normal state the fluid distributed in every part of the body, namely, the juices of the flesh. A change in the quality of the gastric juice, and consequently in that 136 SALTING OF FLESH. of the products of the digestive process, must be regarded as an inevitable result of the long-con- tinued use of Salted meat ; and if during digestion the substances necessary to the transformation of that species of food be taken from other parts of the organism, these parts must lose their normal condition. Effects?- I* 1 mv experiments on the salting of meat, I U8e< * at ^ rst a species of salt which subsequently P rove d on examination to contain a considerable P r P rt i n f chloride of calcium and chloride of magnesium. I was induced to examine the salt by observing that the brine obtained from meat salted with it contained only traces of phosphoric acid. The external aspect of the salted flesh sufficiently explained this unexpected fact ; for it was covered as if with a white froth, consisting chiefly of phos- phate of lime and phosphate of magnesia. The earthy salts of the sea salt had entered into mutual decomposition with the alkaline phosphates of the juice, producing phosphates of lime and magnesia, of which only very small quantities could be dis- solved in the acid brine. Meat thus In the use of a salt, rich in lime and magnesia, salted may . be less un- there may thus be a cause which renders the meat salted with it less injurious to the system. For it is plain that when, along with such meat, vegetables are eaten which are rich in potash (and this is the case with all esculent vegetables), the conditions are present which determine the reproduction, during IMPORTANCE OF THE SOLUBLE PARTS OF FLESH. 137 digestion, of the deficient alkaline phosphates. That these latter salts may actually be formed under such circumstances, is shown by the analysis of milk, a fluid rich in alkaline phosphate, compared with that of the fodder or food of graminivorous animals, which last contains no alkaline phosphates, but phos- phates of lime and magnesia along with salts of the alkalies with other acids. When we compare flesh with other animal food, Flesh com. such as eggs and cheese, the difference is striking, and the difficult digestibility of the latter, when compared with flesh, unquestionably depends on the difference in their composition. If we consider that the juice of flesh, in all The soluble animals yet examined, possesses a constant character; ent s S f the that, exclusive of those constituents which are de- rived from the blood unavoidably mixed with it, as well as of small quantities of odorous and sapid tlons * substances on which the characteristic secondary or by-taste of the juice or soup of the flesh in each kind of animal depends, the juice of ox-flesh is in no way distinguishable from that of the fox, it seems justifiable to conclude, that the quantity and the nature of the soluble constituents in the muscular system are essential to the functions of the muscles. It appears further to follow, that in judging of the Nutritive nutritive qualities of any kind of food, the composi- animaHbod tion of the blood cannot be selected as the proper ascertained datum from which to argue, because there are a number of factors which must be brought into the biood fthe alone. 138 LACTIC ACID IN THE GASTRIC JUICE. calculation, and which are either wanting in the blood, or present in it only in trifling quantity. Lactic acid Some experiments have lately been made by the^astric Lehmann on the gastric juice of dogs, fed on bones dogs by an d lean horse-flesh, which fluid he has studied more e mann. m i rm tely than had previously been done. He ob- tained from it a crystallised salt of magnesia, com- bined with an organic acid, not containing nitrogen. This salt yielded 16*6 p. c. of magnesia, and 21 p. c. of water of crystallisation. Now that we know that lactic acid forms a constituent of the chief mass of the body, it is evident that Lehmann's mag- nesian salt, which agrees with lactate of magnesia in the proportion of base and of water of crystal- lisation, really was lactate of magnesia. In that The digest, case the gastric juice contains lactic acid, and thus the problem of the digestive process in the stomach would appear, in its chemical aspect, to be com- pletely solved. The gastric The experiments of all who have studied the gas- lar to the trie juice agree in this, that that fluid contains, along flesh. with an organic acid, free phosphoric acid or an acid phosphate, and in this respect its similarity with the juice of the muscles is strikingly obvious. That portion of the gastric juice which is soluble in alco- hol is, in its reaction, identical with the alcoholic extract of soup, as Tiedemann and Gmelin have already shown ; and the soup or infusion of meat, free from gelatine and fat, the preparation of which Tte soup I have described (ante, p. 131), may perhaps admit VOLATILE ACIDS OF GASTRIC JUICE. 139 of being employed as a valuable remedy for many formerly ' described dyspeptic patients, with a view to increasing the proposed as . a remedy in activity of the stomach, and promoting digestion, dyspepsia. Again, if the blood or the muscular substance of emaciated convalescents cannot supply the matters necessary for digestion in sufficient quantity for a rapid reproduction of the lost strength (that is, the lost parts of the organism) the benefit derived from its value to convales- well-made soup during convalescence admits of a cents. simple explanation. Finally, when we recollect, that lactic and phos- Ori g in of Y the hydro- phoric acids, at temperatures in which hydrochloric, chloric and _ . . . , J other vola- acetic, and butyric acids are volatilised, are almost tile acids . r i . i * . obtained by fixed, we can explain how it happens that in many distilling cases hydrochloric acid, in others acetic or butyric juice. acid, has been obtained by distilling the gastric juice. Acetates, butyrates, and even chloride of sodium, are decomposed by lactic acid, as well as by acid phosphates, in these circumstances, and the occur- rence of the one or the other of the more volatile acids must vary with the amount of the lactic or phosphoric acid present in the gastric juice, and the amount also of their salts in the same fluid. CONCLUSION. I think it right to state, distinctly, that I am far These re- from considering the nature and quality of the substances occurring in the juice of flesh as fully 140 THE SUBJECT NOT EXHAUSTED. more com- ascertained by the investigation contained in the tigationT 68 " preceding pages. On the contrary, I am of opinion, that it ought only to be regarded as the commence- ment of a more complete work. But the minute study and thorough investigation of those substances, contained in that fluid, which have not yet been studied, demands so much time, that I did not wish to delay the publication of the results hitherto obtained till the completion of my researches. Various ^ ^ ne tissue called muscular, fibrine and albu- to^fdfc! 8 men are *^e cme f constituents in fully-developed hTthe mut anmia l s ' This tissue is everywhere interwoven with cuiartissue. delicate membranes, and a number of minute ves- sels are ramified throughout it, which are filled, partly with coloured, partly with colourless fluids. No other part of the body absorbs so large a part of the nervous system. As Berzelius points out, we must distinguish fibrine, albumen, and cellular tissue, partly organised, partly in the state adapted for their conversion into organised structure ; and lastly we have, in the fluids, these substances in the effete state, or in the condition best adapted for their removal. We have also to distinguish the coloured and colourless fluids brought to the mus- cle in the vessels ; and the membranes of the dis- tributed nerves as well as the substance itself of those nerves. Province of When analysis shall have become so perfect as analysis, to enable us to separate these different substances in a rational manner, she will have fulfilled her SUBSTANCES IN FLESH NOT YET STUDIED. 141 duty. At present, analysis begins by mixing them altogether, and a chemical result is obtained, which gives room for a multitude of questions. These questions are, in the present state of our knowledge, the conditions of further progress. Kreatinine and Kreatine are constituents of Kreatine and kreati- the muscles, but they are also constituents of urine ; nine occur and if any process in the living body depends upon muscle and their presence, it is evident that only that portion of these two compounds can pass into the urine, which has not been employed for vital purposes. The examination of the urine in diseases will pro- bably very soon shed light on this question. That portion of the juice of flesh which is solu- Gelatinous ble in cold water, but not in alcohol, possesses all the juice of the properties of gelatine, except that of gelatinis- ing when concentrated. It is precipitated by tannic acid ; the precipitate softens like plaster in hot water, and cannot be distinguished from the tan- nate of gelatine by its aspect. A second substance, which I have not yet further Another investigated, separates, during the evaporation of inthejnke the juice of flesh, in the form of a skin or membrane, which no longer dissolves in cold water, but swells up and becomes mucilaginous. It is not, as might be imagined, caseine. Of the substances soluble in alcohol, the greater Unknown part consists of one or probably of more bodies, par- isedbodies ticularly rich in nitrogen; these are the substances, which, after the phosphoric acid has been removed, 142 NO UREA NOR URIC ACID give rise, on incineration of the residue, to so great a mass of cyanide of potassium. New acid When that part of the juice of flesh which is in the juice , _ , , of flesh, not soluble in alcohol and m ether is mixed with sul- phuric acid, to separate the alkali, and the filtered liquid is left at rest for some days, there are depo- sited long transparent colourless needles, which have a strong acid reaction and contain no alkali. I first noticed this substance at the close of this investiga- tion, and obtained too small a quantity to enable me to analyse it. Another ni- Lastly, if the acid liquid thus obtained be satu- trogenised acid in rated with lime, evaporated to dryness, and the residue washed with alcohol, the addition of ether to the alcohol causes a deposit ; and the liquid sepa- rated from this contains kreatinine, combined with an organic acid, rich in nitrogen, which I have, in like manner, not yet more minutely examined. Urea not I have taken the utmost pains to detect urea or thTjuk-e of uric acid in the juice of flesh, and I believe that I should have succeeded in doing so, even had no more than one-millionth part of these substances been present. According to my experiments, there- fore, urea is not a constituent of the juice of flesh. Uric acid In one case only where I had added chloride of to have barium to the alcoholic solution of the extract of in it on one flesh, crystalline flocculi separated after exposure only. r for weeks in the air. These were not dissolved by hot water or in hydrochloric acid, but dissolved in nitric acid, with disengagement of red fumes, IN THE JUICE OF FLESH. 143 exactly like uric acid ; and the solution gave with ammonia the same purple colour which uric acid would have given in like circumstances. This substance, however, I have not been able again to procure. ADDENDUM. NOTE BY THE EDITOR. From the mother-liquor which had deposited the kreatine which I prepared and which con- tained the soluble matter of nearly 7 Ibs. of fowl, I obtained, by the process indicated at p. 77, by the author, 4 grammes, or about 61 grains of pure and well-crystallised inosinate of baryta. It is certain that I did not succeed in obtaining the whole of the inosinic acid originally present in the juice ; but the above quantity was procured without difficulty ; and it would therefore appear that in fowl, at least, the quantity of inosinic acid is not so small or insignificant as the author seems to think. TABLE SHOWING THE PROPORTION BETWEEN THE ENGLISH AND HESSIAN STANDARD OF WEIGHTS AND MEASURES. 1 lb. English is equal to 0-90719 Ibs. Hessian. 1 Hessian acre is equal to 26,910 English square feet. 1 English square foot is equal to 1-4864 Hessian square feet. 1 English cubic foot contains 1-81218 of a Hessian cubic foot. INDEX INDEX. A. ABSORBENT POWER OF BLOOD for carbonic acid gas, 112. De- pends on the presence of phosphate of soda, 113. ACID reaction of the juice of flesh, 28. ACID. Butyric. Is formed in the oxidation of blood constituents, 27. Is formed in the fermentation of sugar, in contact with animal matter, 8. Its occurrence in the gastric juice explained, 139. Carbonic. Its absorption by blood, 112. By phosphate of soda, 117. Inosinic. Its preparation from the juice of flesh. 77. Its properties, 78. Its composition, 79. Lactic. Its existence in flesh hitherto doubtful, 29. It exists in the juice of flesh, 88. Its extraction, 89. It exists in the gastric juice, 138. Is consumed in respira- tion, 103. Phosphoric. Occurs in large quantity in the juice of flesh, 43. Its modifications, 95. They are found in the ashes of flesh, 97. Sulphuric. Not found in the juice of flesh, 43, 95. Tannic. Used in the extraction of lactic acid from fish, 90. Uric. Its oxidation, 14. Is not found in the juice of flesh, 142. ACIDS, free, in the juice of flesh, 99. Accumulation of, in some morbid states, 108. ACTION. Of chloride of sodium on phosphate of potash, 110. Of acids on kreatine, 52. Of bases on kreatine, 68. 148 INDEX. ALBUMEN. Its constitution, according to Mulder, 16. Occurs abundantly in the juice of flesh, 40, 125. Is dissolved by cold water, 125, 130. Is found in the brine of salt meat, 134. Of eggs, contains more sulphur than that of serum, products of its oxidation, 27. Temperature at which it coagulates, 126. ALKALI. Organic in flesh, 85. ALKALIES. Predominate in the ashes of flesh, 94. ALKALINE. Reaction of blood, 41, 104. Is due to the pre- sence of phosphate of soda, 116. Reaction of the ashes of the juice of flesh, 97. Phosphates essential to animal life, 110, 112. ALLIGATOR. Its flesh contains kreatine, 35, 46. ANALYSIS. Ultimate improperly used, 10. True province of, 140. Of kreatine from flesh, 48. Of kreatinine from ditto, 59. Of kreatine and kreatinine from urine, 63. Of inosinic acid, 79. Of lactates from flesh, 91. Of sarcosine, 70. Of the salts of kreatinine, 66, seq. Of the salts of sarcosine, 71, seq. Amount of kreatine obtained from flesh, 46. ANATOMY. More advanced than Animal Chemistry or Physio- logy 5. ASHES. Of the juice of flesh are alkaline, 97. And contain the different modifications of phosphates, ib. Of inland plants, contain no soda, 109. Of maritime plants, contain soda, ib. Of sea plants, contain more potash than soda, ib. B. BARYTA. Used to separate the acids from the juice of flesh, 43. Its action on kreatine. 52. BASES. Alkaline in flesh, 94. BEEF. Amount of kreatine in, 46. BERZELIUS. His opinion on the nature of the acid in flesh, 28. His opinion on the nature of kreatine, 34. BLOOD, Its absorbent power for carbonic acid depends on phos- phate of soda, 112. Phosphate of soda indispensable to, ib. BRACONNOT. One of the few who have devoted themselves to Animal Chemistry, 1. Finds lactic acid in the juice of beet- root and rice-water, 31. BRAIN. Contains no kreatine, 47. Two new acids in, ib. INDEX. 149 BOILING OF FLESH, its effects, 122. Best mode of, for eating, 126. Best mode of, to yield good soup, 128. Water dissolves little gelatine from meat, 129. BOPP. His experiments on caseine, albumen, &c., 27. BOUILLI. Not nutritious without the bouillon, 122. BRINE, the, of salt meat contains all the soluble matters of the flesh, 134. BUFF, Prof. His voltaic circle with flesh, blood, and brain, 104 (note). C. CAFFEINE. Its relation to kreatinine,59. CALF. Flesh of . See VEAL. CARAMEL. Used to colour soup, 132. CARBONIC ACID. See ACID, Carbonic. CASEINE. Its oxidation, 27. CHEMISTRY. Animal, must go hand in hand with Anatomy and Physiology, 4. CHEVREUL. Importance of his researches, 1. On kreatine, 32. CHLORIDE OF SODIUM. Its action on phosphate of potash, 110. Of sodium must be added to the food of animals, 109. Of potassium in the juice of flesh, 97. Double, of platinum and kreatinine, 66. Double, of platinum and sarcosine, 72. COLOUR OF SOUP affects our judgment of its taste, 132. CONVALESCENTS. Extract of flesh, or strong soup recommended for, 139. CYANIDES. Formed in the ashes of the juice of flesh, if the phosphoric acid be first removed, 105. D. DEER. Red, flesh of, contains kreatine, 46. Roe, flesh of, con- tains kreatine, ib. E. EDITOR'S note on the amount of kreatine in flesh, and its pre- paration from fowl, 46. On the preparation of inosinate of baryta from fowl, and its amount, 143. On stock, and erro- neous modes of dressing meat, 123. 150 INDEX. ELECTRIC currents produced by Buff from flesh, brain, and blood, 104 (note). ELECTRICAL currents may exist in the organism, 104. ENGELHARD and MADDRELL. On lactic acid and lactates, 92, 93 (notes). EQUATIONS. Fallacious, illustrated, 14 ; of Mulder for proteine compounds shown to be erroneous, 16. ERDMANN. On incineration of wheat, &c., 116 (note). ERYTHROPROTIDE, 16. EXTRACT OF FLESH, or true portable soup, 132. Recommended for wounded men, for ships and fortresses, 133. F. FELLENBERG On albumen, &c., 21. FERMENTS. Animal, their varied action on sugar, &c., 7. FIBRINE. Of flesh, hardened by boiling with water, 38, 125. FISHES. Flesh of, contains kreatine, 44, 46. Contains lactic acid, 90. FLAVOUR. Of soup depends on the matters soluble in cold water, not on gelatine, 128, 131. FLESH. Juice of substances found in, 28. See JUICE. FORTRESSES. Provision for, should include some extract of flesh, 133. FOWLS. Flesh of, contains the largest proportion of kreatine, 46. Sooner dressed than beef or mutton, 127. Fox. Flesh of, contains kreatine, 46. Flesh of wild, yielded far more kreatine than that of a tame one, fed on flesh, 45. G. GASTRIC JUICE. Contains lactic acid, 138. Resembles the juice of flesh, ib. GAY-LUSSAC and THENARD. Their researches on fibrine, albu- men, &c., 21. GELATINE. Not the cause of the strength or flavour of soup, 128, 131. GELATINOUS MATTER. In the juice of flesh, not yet studied, 141. GLYCOCOLL. Its relation to kreatine, 51. INDEX. 151 GMELIN, L. His researches in Animal Chemistry, 1. and TIEDEMANN on gastric juice, 138. H. HARE. Flesh of, contains kreatine, 46. HEART. Of the ox contains kreatine, 47. HENNEBERG. On the ashes of the blood of fowls, 106. HERBIVORA. When fed on inland plants require salt, 110. HYDROCYANIC ACID. Its relation to hydrochloric acid. 20. I. INLAND PLANTS. Contain no soda, 109. INORGANIC constituents of the juice of flesh, 93. Of blood, 104. Of the juice of flesh and those of blood compared, 105. INOSINATES, 80. INOSINIC ACID, 77. INSOLUBLE ingredients of the ashes of the juice of flesh, 94. J. JUICE OF FLESH. Always acid, 28. Equilibrium of the free acids in, 98, seq. Kreatine from, 39. Contains kreatinine, 85. Contains lactic acid, 88. Contains inosinic acid, 77. Con- tains phosphoric acid, 43. Contains albumen, 38, 40. Con- tains phosphate of potash and chloride of potassium, 95, 104. Contains some substances not examined, 141. JUICE, Gastric. See GASTRIC JUICE. K. KIDNEYS. Contain no kreatine, 47. Function of, 101. KREATINE. Discovered by Chevreul, 32. Seen by Wohler, and by Schlossberger, 35. Exists in all the higher animals in the flesh, 46. Occurs in urine, 60. Mode of extracting, 38, seq. Amount of in flesh, 45. Action of acids on, 52. Action of bases on, 68. KREATININE. A powerful base, 52. Salts of, 66. Exists in urine, 60. Is found even in putrid urine, 64. 152 INDEX. ^. KREATINE AND KREATININE. Their function not ascertained, 141. L. LACTAMIDE. Isomeric with sarcosine, 76. LACTATES. From flesh, analysis of, 91. LACTIC ACID. See ACID, Lactic. LASKOWSKI. Onproteine, 19, 27. LEHMANN. On gastric juice, 138. LEUCINE. A product of decomposition of albumen, &c., 27. LIME. Lactate of, 92. LYMPH. Is alkaline, 104. M. MADDBELL and ENGELHARD. On lactic acid, 92, 93 (notes). MAGNESIA. Found in the juice of flesh, as phosphate, 43, 94. Alkalies and lime, proportions of in juice of flesh, 121. MARCHAND. On the blood, 115. MARITIME COUNTRIES. Plants of, contain soda, 109. MARTEN. Flesh of, contains kreatine, 45, 46. METHOD. Of investigation in Animal Chemistry, 1. Of ob- taining accurate formulae, 12, 13. Of extracting kreatine from the juice of flesh, 39. Of extracting kreatine and kreatinine from urine, 61. Of preparing kreatinine from kreatine, 53. Of preparing sarcosine from kreatine, 68. Of extracting inosinic acid from the juice of flesh, 77. Of extracting lactic acid from ditto, 88. Of boiling meat that is to be eaten, 126. Of boiling meat for the soup, 128. Of making soup, 131. Of preparing the extract of meat, 132. MICHAELIS. On albumen, &c., 21. MILK. Contains much potash with very little soda, 108. MITSCHERLICH, C. On lactic acid, 31. MULDER. His thory of proteine, 15, 23. His tabular view of the action of potash on albumen, 16. His table of proteine compounds, 25. MULDER'S process does not yield proteine free from sulphur, 27. MUSCLE. See FLESH. FIBRINE. MUSCLE. Fluid of. See JUICE OF FLESH. INDEX. 153 MUSCULAR SYSTEM. Contains a great variety of ingredients as well as of tissues, 140. MUTTON. Contains kreatine, 46. N. NECESSITY, supposed, for the identity in composition of fibrine, albumen, and caseine, shown to be an error, 19, 21. O. OXIDATION OF CASBINE, Albumen, &c., 27. Lactic acid in the process of respiration, 103. P. PARMENTIER. On extract of meat, 133. PETTENKOFER. His compound from urine, consists of kreatinine and kreatine, 60, 65. His compound prepared by a simple process, 61. PHOSPHATE. Of soda, essential to blood, 112. Of soda how formed in the system, 111. Of potash in juice of flesh, 108. Of magnesia in juice of flesh, 43, 94. Of lime in juice of flesh in very small quantity, 43, 121. PHOSPHATE OF SODA in blood cannot be replaced by phosphate of potash, 112. Is the cause of the alkaline reaction of blood, 116. Its power of absorbing and giving off carbonic acid gas, 117. PHOSPHATES. Characters of the modifications of, 96. Removed from flesh in salting, 134. PHOSPHORIC ACID. See ACID, Phosphoric. PHOSPHORUS. Its existence in albumen, fibrine, &c. not proved, 23, 25. PHYSIOLOGY. Too much separated from Chemistry, 4. PIG. Flesh of, contains kreatine, 46. PIKE. Flesh of, contains kreatine, 46. Contains lactic acid, 90. PLATINUM. Double salts of, with kreatinine, 66. Sarcosine, 72. PORTABLE SOUP. True, 132. Commercial, ib. Characters of genuine, 133. M 154 INDEX. POTASH. Predominates in juice of flesh, 104, 106. And in milk, 108. POULTRY. Contains much kreatine, 46. Is sooner dressed than beef or mutton, 127. PROTEINE. Mulder's theory of, is fallacious, 15, 23. As a compound free from sulphur does not exist, 27. PROTIDE, 16. PROUST. On the extract of meat, 133. R. RED DEER. Flesh of, contains kreatine, 46. ROASTING OF FLESH, 125, 127. With a covering of lard, 127. ROE DEER. Flesh of, contains kreatine, 46. RULING. On the amount of sulphur in blood constituents, 27. S. SALICINE. Its true formula how discovered, 13. SARCOSINE. Obtained from kreatine is a base, 68. Salts of, 71. SAUERKRAUT. Heightens the flavour of meat, 124. SAUSSAURE, DE. His researches in Vegetable Chemistry, 1. SCHEERER. On the absorption of carbonic acid by the blood, 112. SCHLOSSBERGER. On kreatine in the flesh of the alligator, 35. SEA PLANTS. Contain more potash than soda, 109. SHEEP. Flesh of, contains kreatine, 46. SHIPS. Their provision should include extract of meat, 133. SODA. Phosphate of, essential to blood, 112. Carbonate of, is not the cause of the alkaline reaction of blood, 116. SODIUM. Chloride of, use in the organism, 111. SOLUBLE MATTERS. Of flesh, 130. Of flesh are lost in salting, 134. Salts form the chief part of the ash of the juice of meat, 94. SOUP. How to boil meat for, 128. Best mode of preparing, 131. Portable, or extract of flesh, how prepared, 132. Uses of, 133. STEWING. Preferable to boiling, 124 (note). STOCK. The, of cooks, its nature, 123 (note). STRENGTH. The, of soup depends, not on gelatine, but on the INDEX. 155 matters soluble in cold water, 128. Restored, in wounded men, by extract of meat, 133. SUGAR. Action of animal substances on, varies with the state of the animal matter, 7. SULPHATE OF KREATININE, 67 ; sarcosine, 72. SULPHUR. More abundant in blood constituents than was for- merly supposed, 27. According to Mulder, combines with proteine, 23. Is more abundant in albumen of eggs than in that of serum, 27. Exists in two states of combination in albumen, fibrine, &c., 26. SULPHURIC ACID. Not found in the juice of flesh, 43. s T. TANNIC ACID. See ACID, Tannic. TESTS. For genuine extract of meat, 133. For kreatine in the juice of flesh, or in urine, 61, 85. For lactic acid, 89. For the different forms of phosphoric acid, 96. THEINE. See CAFFEINE. THENARD. On Albumen, &c., 21. THEORIES. Never absolutely true, 18. THEORY OF PROTEINE. Unfounded and fallacious, 19. TIEDEMANN and GMELIN. On the Gastric Juice, 138. TYROSINE. A new substance discovered by the Author as a pro- duct of decomposition of albumen, fibrine, &c., 27. U. ULTIMATE ANALYSIS. Its effects on the progress of the science, 10. True value of, 11. Requires control, 12. Cannot alone determine the true formula of a compound, 13. UNDERDONE MEAT, 127. UNKNOWN SUBSTANCES. In the juice of flesh, 141, 142. UREA. Formed from kreatine by the action of bases, along with sarcosine, 75. Not present in the juice of flesh, 142. URETHANE. 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