UC-NRLF I ! ! If U DjH Elm ri 1 i LIBRARY UNIVERSITY OF CALIFORNIA DAVIS i c C RESEARCHES ON THE" CHEMISTRY OF FOOD, MOTION OF THE JUICES IN THE ANIMAL BODY. BY JUSTUS LIEBIG, M. D., PROFESSOR OF CHEMISTRY IN THE UNIVERSITY OF GIESSEN. EDITED FROM THE MANUSCRIPT OF THE AUTHOR, BY WILLIAM GREGORY, M. D., PROFESSOR OF CHEMISTRY IN THE UNIVERSITY OF EDINBURGH. EDITED FROM THE ENGLISH EDITION, BY EBEN N. HORSFORD, A. M., RUMFORD PROFESSOR IN THE UNIVERSITY AT CAMBRIDGE. LOWELL: DANIEL BIXBY AND COMPANY. 1848. LIBRARY UNIVERSITY OF CALIFORNIA Entered according to Act of Congress, in the year 1848, by DANIEL BIXBY AND COMPANY, in the Clerk's Office of the District Court of the District of Massachusetts. CAMBRIDGE I M E T C A L F AND COMPANY, PRINTERS TO THE UNIVERSITY. PREFACE. TO THE AMERICAN EDITION. IN the following pages, the style is a little more scientific than that of the author's Agricultural Chemistry. It may have been made so, in the knowledge that his previous works have been gen- erally read, and the readers thereby prepared for an additional effort in the perusal of this. A few changes in terminology from the English edition have been made, not without hesitation, nor yet without consultation. Hydrosulphuric acid, for sulphuretted hydrogen, and sulphide, for sulphuret, are already elsewhere in use. The compounds formed by iodine, bromine, and chlorine, when hydroiodic, hydrobromic, and hy- drochloric acids are poured into salts of the heavier metals, as silver and lead, are called iodides, bro- mides, and chlorides. There is no sound reason why this nomenclature should not be extended to the sulphur compounds from hydrosulphuric acid with the same metals. iv PREFACE TO THE AMERICAN EDITION. The word alkaline is employed generally among English and American chemists with two entirely distinct significations, 1st. As qualifying a reaction, and distinguishing it from acid or neutral ; and, 2d. As indicating the base in a salt, implying that it is either potassa, soda, lithia, or ammonia. The first applies to solutions, not only of alka- lies, but of alkaline earths and many of the high- er metallic oxides, and certain of the basic and neutral salts. There is here an obvious deficiency. I venture to suggest the word alkalic for the second case, where the adjective refers to a salt of potassa, soda, lithia, or ammonia, retaining the epithet al- kaline exclusively to qualify the reaction of any base or salt which imparts, in solution, a blue tint to reddened litmus, or changes the yellow of cur- cuma to brown. This is but adopting the nomenclature of Ber- zelius, upon which, in fact, nearly all chemists act, in giving the first place to the base in their formulae of salts. The confusion which will be avoided by the employment of these two words in their respective places will be appreciated by turning to page 82. What, for example, is "an acid alkaline lactate," or a " neutral alkaline phosphate " ? On the receipt of the first part, " Researches on PREFACE TO THE AMERICAN EDITION. V the Chemistry of Food," there were prepared in the Cambridge Laboratory, from the flesh of wild pigeons (Columba migratoria], kreatine, sarcosine, and inosinic acid, in considerable quantities. The lean meat of a hundred and forty pigeons made the quantities sufficiently large to operate upon advan- tageously. The processes here given are, with the aid of a good press, exceedingly easy to follow. The second part, which was received from the author by the steamer of the 27th of March, has been translated and edited, as was the first part, by Professor Gregory of the University of Edinburgh. The importance of the principles established in relation to the transpiration of liquids must im- press itself on every one interested (and who is not?) in the preservation of health. In a letter addressed to the editor, dated Giessen, November 5th, 1847, Professor Liebig, after briefly detailing the course of experiment and general con- clusions, says : " The application of these results to the animal body scarcely requires more detailed explanation. The surface of the body is a mem- brane from which evaporation goes uninterruptedly forward. In consequence of this evaporation, all the fluids of the body acquire, in obedience to at- mospheric pressure, motion towards the evaporating surface. This is obviously the chief cause of the passage of the nutritious fluids from the bloodves- sels, and of their diffusion through the body. vi PREFACE TO THE AMERICAN EDITION. " We know now what important functions the skin (and lungs) fulfil through evaporation. It is a condition of nourishment, and the influence of a moist or dry air upon the health of the body, or of mechanical agitation by walking or running, which increases the perspiration, is self-evident." In view of the results of this investigation, the author remarks, in a letter bearing date January 6th, 1848: "I consider this investigation the most important I have ever made." This estimate which Professor Liebig has placed upon his own work will make it not the less ac- ceptable to the physiological public. It will be read with increased interest from the attention which Matteucci's work, and particularly that part of it relating to Endosmosis and Exosmosis, has called to this department of inquiry. The susceptibility of some persons to changes in the condition of the atmosphere, the value of Franklin's air-bath, the advantages of regular sea or fresh-water bathing, some of the effects of hy- dropathic treatment, the consequences of drought on vegetation, the renewed greenness and life after a shower, the influence of winds blowing from off a sheet of water, a mountain, or a sand-plain, and many other phenomena hitherto but obscurely understood, all find a more or less perfect expla- nation in the experimental results recorded in the following pages. PREFACE TO THE AMERICAN EDITION. Vll In relation to the potato disease, the views of the author give harmony to a large class of facts upon record, and the method of Dr. Klotzsch, which promises so well, seems a practical applica- tion of these views. It has been stated, that, during the last year or the year previous, several swaths were spread through a potato field while the tops were young and green, and that those hills, the tops of which had been partly removed, contained at harvest time only sound potatoes, while everywhere else throughout the field the tubers were infected by the rot. A farmer on Long Island caused the blossoms as they appeared in his potato field to be picked off, and found only sound potatoes in the hills at har- vest time. These facts have a new interest and significance from the support which they lend to the views of Baron Liebig and the method of Dr. Klotzsch. It is to be hoped that this method will meet with a faithful trial. EBEN N. HORSFORD. CAMBRIDGE, May 12, 1848. CONTENTS. ON THE CHEMISTRY OF FOOD. PAGE PREFACE TO THE ENGLISH EDITION xxi AUTHOR'S PREFACE . . * xxix SECTION I. On the methods of investigation to be pursued in Animal Chemistry 1 Want of connection between Chemistry and Physiology . 4 Animal tissues and compounds act as ferments ... 6 The changes going on in the body are little known . . 8 The results of ultimate analysis of animal substances have been unsatisfactory 9 Necessity for control to ultimate analysis .... 10 Erroneous methods of control adopted 11 Mulder's theory of Proteine 13 It is not tenable 13 Theories are never absolutely true, but only true for the period 15 Fallacious conclusions drawn from the analysis of fibrine, al- bumen, &c 16 Identity of composition not necessary 17 Erroneous views deduced from the Proteine theory . . 17 Proteine does not exist 21 There is much to be done in regard to the constitution of fibrine, albumen, &c 22 X CONTENTS. SECTION II. Acid reaction of the juice of flesh ..... 23 Observations of Berzelius on the juice of flesh ... 23 The presence of lactic acid in it doubtful .... 24 Kreatine discovered by Chevreul, in 1835 .... 27 His account of it . . 27 Berzelius on kreatine 28 Wohler and Schlossberger on kreatine 29 Investigation of the juice of flesh 30 Extraction of the soluble constituents of flesh ... 31 It is necessary to use large quantities .... 32 Game and fowl yield most kreatine 34 The liquid always acid, even when mixed with blood . 34 Separation of the phosphoric acid 35 Modification of the process for fish 36 Kreatine crystallizes 36 Its amount in different kinds of flesh .... 37 It occurs in all the higher animals 38 Kreatine 39 Analysis of kreatine 39 Properties of kreatine 42 Action of acids and bases on it 43 Kreatinine, its preparation 44 Its properties 46 It is a powerful base 47 Its composition 48 Its relation to kreatine 48 Analysis of kreatinine 49 Kreatine and kreatinine in urine ..... 50 Pettenkofer's compound 50 Improved method of preparing it . . . . 51 It consists of kreatinine and kreatine ..... 53 Kreatinine alone is found in putrid urine .... 53 Salts of kreatinine 55 Sarcosine, its preparation ..... 56 Its properties ........ 53 CONTENTS. XI Its analysis 58 Salts of sarcosine '59 Its formula 61 Its relation to kreatine 62 It is isomeric with lactamide and with urethane . . 63 Inosinic acid, its preparation 63 Its analysis 65 Its formula 66 Inosinates 66 Probable constitution of the acid 69 Kreatinine exists ready formed in flesh .... 70 Lactic acid, as a constituent of flesh 73 Method of extracting it 73 Modification of the process for fish ..... 74 Analysis of lactates from flesh and fish .... 75 Inorganic constituents of the juice of flesh . . .77 Large amount of inorganic salts in flesh .... 77 Large proportion of soluble phosphates 77 The ashes of flesh contain no carbonates, only phosphates and chlorides 78 The different modifications of phosphates are present in these ashes 79 Characters of the phosphates 79 In certain kinds of flesh, the whole alkalies are not sufficient to form tribasic phosphates 82 In fowl they are not sufficient even to form bibasic phosphates 82 Equilibrium between the free lactic and phosphoric acids in the juice of flesh 83 The ashes of flesh always alkaline 83 Importance of these facts in explaining the vital processes 84 Lactic acid cannot be detected in normal urine, whether it be acid or alkaline 84 It is therefore consumed in the respiratory process, and in this form sugar, starch, &c., are employed in respiration . 86 The blood and lymph are always alkaline, the juice of mus- cle is always acid 86 These conditions may give rise to electrical currents . 87 Xii CONTENTS. The juice of flesh contains phosphate of potash and chloride of potassium 87 While blood and lymph contain phosphate of soda and chlo- ride of sodium 87 Relative proportions of soda and potash in the juice of flesh and in blood .87 The juice of flesh, if it could be obtained free from blood and lymph, would perhaps contain no soda .... 89 The permeability of the vessels for the different fluids must be different 89 Morbid accumulation of free acid destroys the bones . 90 Importance of chloride of sodium as a part of the food of ani- mals ,90 Inland plants contain only salts of potash .... 91 Maritime and even sea plants contain much more potash than soda .91 Mutual action of phosphate of potash and chloride of sodium 92 It produces phosphate of soda 93 Phosphate of soda is indispensable to the blood ... 93 Its importance in respiration ...... 93 Relation of blood to carbonic acid gas ..... 93 Its absorbent power is not owing to the presence of carbonate of soda 94 Experiments to prove this ....... 95 Remarkable properties of phosphate of soda, to which the blood owes its power of absorbing and giving off carbonic acid 97 The study of the influence of salts, acids, and alkalies on respiration and digestion will lead to valuable results in medicine 100 Relative proportions of lime and magnesia in the juice of flesh 100 SECTION III. General results 101 Practical applications to cookery 101 Action of cold water on flesh ... 102 CONTENTS. xiii Stock contains the soluble constituents of flesh . . . 103 Nature of soup 103 Albumen in flesh ......... 104 It is the cause of tenderness 104 Action of hot water on flesh 105 Best method of boiling meat 105 Temperature required 105 Underdone meat 105 Poultry sooner done than beef or mutton .... 106 Use of a covering of lard in roasting 106 Best method of boiling meat to obtain soup from it . . 106 The bouilli is neither nutritious nor digestible without the soup 107 Gelatine not the source of the strength or flavor of soup . 107 Amount of gelatine dissolved by boiling water . . . 107 Amount of matter dissolved by cold water .... 108 Poultry contains much soluble matter . . . . 109 The nutritious and sapid ingredients of soup exist in it ready formed 109 Best mode of preparing soup 109 Influence of the color of soup on our judgment of its taste . 109 Extract of meat, or true portable soup .... 110 The portable soup of commerce is nearly pure gelatine . 110 Beef yields ^d of extract 1 10 Extract of meat recommended as a restorative for wounded persons 110 Characters of true and false extract . . . . Ill Extract of meat will be useful in ships, fortresses, &c., where much salt meat is consumed Ill Salting of meat . Ill The brine contains the soluble ingredients .... Ill Salt meat is therefore deficient in nutritive qualities . . 112 Causes of this 112 Effects produced by salt containing chlorides of calcium and magnesium 113 Meat salted with such salt may be less unwholesome . .113 Flesh compared with other animal food . . . . 114 CONTENTS. The soluble constituents of muscles must be essential to their functions H4 Lactic acid exists in the gastric juice The digestive process, in a chemical point of view, now cleared up 115 The gastric juice resembles the juice of flesh . . . 115 Soup or extract of flesh suggested as a remedy for dyspepsia, and for convalescents 115 Origin of hydrochloric and other volatile acids in the gastric juice CONCLUSION. These researches are only the commencement of what must be an extensive series . 116 Various substances distinguishable in the muscular substance 116 True province of chemical analysis 117 Kreatine and kreatinine, occurring both in muscle and in urine, must serve some purpose in the organism not yet ascertained 117 There is a gelatinous substance, not gelatine, in the cold infu- sion of flesh, not yet studied 117 Also, a body resembling caseine, not yet examined . . 117 Also, two new nitrogenized acids, not yet investigated . 118 The juice of flesh appears to contain neither urea nor uric acid 118 But on one occasion the author obtained a trace of a substance resembling uric acid . . . . . . . .118 CONTENTS. XV ON THE MOTION OF THE JUICES IN THE ANIMAL BODY. PAGE PREFACE TO THE ENGLISH EDITION .... 123 AUTHOR'S PREFACE .... . 127 On the phenomena accompanying the mixture of two liquids separated by a membrane 129 Relation of porous bodies to water and other liquids . . 130 The moistening of porous bodies depends on capillary attrac- tion . 131 Pressure required to cause liquids to pass through membranes 133 The pressure varies with different liquids .... 134 The absorbent power of the membrane has a share in the ef- fect 135 Action of brine, oil, alcohol, &c., on moist membranes . 136 Cause of the shrivelling of membranes when strewed with salt 138 Animal tissues are permeable to all liquids .... 140 Saline solutions, alcohol, &c., mix with water through mem- branes 141 Change of volume when two dissimilar liquids mix through a membrane ; Endosmosis 142 This change of volume does not depend alone on the differ- ent densities 143 Phenomena of the mixture of two liquids through a membrane 143 The mixture is the result of chemical attraction . . . 149 Chemical attraction is everywhere active .... 150 Examples. Crystallization 151 Action of solids on dissolved matters .... 153 Laws of the mixture of two dissimilar liquids . . . 155 Effect of the interposition of a membrane . . . 159 The change of volume in two liquids which mix through a membrane is the result of chemical affinity modifying ca- pillary attraction 160 XVI CONTENTS. Effect of evaporation on liquids confined by membranes . 162 Views of Magnus on Endosmosis 163 Remarks on his theory 164 The nature of the membrane has an important influence . 166 Unequal attraction of membranes for different liquids . 167 The action of two liquids, separated by a membrane, is equiv- alent to pressure, unequal on opposite sides . . . 169 Causes which influence the mixture of two liquids separated by a membrane 174 These causes produce, in the animal body, absorption of the fluids of the intestines into the blood . . . .175 Effects of drinking water and saline solutions of different strengths 176 Influence of the cutaneous evaporation on the motion of the animal juices 179 Experiments 180 Influence of the atmospheric pressure 182 Water passes through membranes more easily than air does 184 Experiments on evaporation through membranes . . . 185 Importance of the cutaneous transpiration . . . 187 By it the fluids acquire a motion towards the skin and lungs 188 Effects of dry and moist air, and of elevation, on the health 188 Causes of the efflux of sweat ...... 190 Fishes die in air, because the due distribution of the fluids is prevented 190 Experiments of Hales on the motion of the sap in plants . 190 This motion is caused by evaporation .... 192 Force with which the sap rises 192 The atmospheric pressure is the active force . . . 193 The sap absorbs gases 194 The evaporation supplies food to the plant . . . 195 Influence of suppressed evaporation on hop-vines . . 195 Observations of Hales on the blight in hops, &c. . . 195 Fire-blasts in hops 197 Hales recognized the influence of evaporation on the life of plants 197 The origin of the potato disease is probably similar to that of the blight in hops 198 CONTENTS. XV11 The disease long known ....... 198 It is due, not to a degeneration of the plant, but to a combi- nation of external circumstances ..... 199 It is connected with the weather, and particularly with the temperature and hygrometric state of the atmosphere , 200 The life of plants is dependent chiefly on four external causes 201 Only one of which, namely, the quality of the soil, is in the power of the agriculturist 201 Effects of suppressed evaporation ; 202 The fungi and putrefaction follow the death of the plant . 202 Observations of Hales on the rise of the spring sap in per- ennial plants 202 Views of Dutrochet 202 Objections to these views 203 The cause of the rise of the sap is transient, and depends on external influences . . . . . . . . 204 It exists, not merely in the spongioles, but in all parts of the plant 205 Experiments of Hales ......... 205 His conclusions . . 206 Gas is given off by the sap 208 The rise may therefore be due to disengagement of gas . 208 The gas is probably carbonic acid 209 APPENDIX. Results of Guckelberger's investigation, sustaining the view, that organized bodies, such as fibrine, albumen, and caseine, are groups of already formed' organic compounds . . 211 Account of a plan proposed by Dr. Klotzsch, of Berlin, for protecting potato plants from disease .... 213 This plan published by authority of the Minister of the Inte- rior of Prussia, on the favorable report of the President of the College of Rural Economy at Berlin .... 218 Conditions on which the reward claimed for his plan, if found effectual, by Dr. Klotzsch, has been granted . . 218 I RESEARCHES CHEMISTRY OF FOOD. PREFACE TO THE ENGLISH EDITION. 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 hon- ored in being intrusted with the duty of convey- ing 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 Phys- iological Chemistry, but for the wrong direction XXU PREFACE TO THE ENGLISH EDITION. unfortunately given to recent researches, and will powerfully contribute to direct into the right chan- nel the energies of those rising chemists to whom Britain must look to sustain her scientific reputa- tion in the present age df rapidly advancing dis- covery in the most recondite parts of Organic Chemistry and of Physiology. The physiologist will also find, in this introduc- tory section, the most convincing reasons to show that, henceforth, it is' indispensable that Anatomy, structural Physiology, and Chemistry should unite their forces with a view to the solution of the great questions which it is the common object of these sciences to solve. With regard to the chemical researches con- tained in the present work, it is most emphatical- ly 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, consequent- ly, 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 impenetrable till they PREFACE TO THE ENGLISH EDITION. XX111 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 ob- scure questions ; and independently of the interest which, in a purely chemical view, they must al- ways have for the chemist, they will be found, by the physiologist 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 inter- pretation. It would indeed appear as if every change in the organism were attended by a defi- nite chemical or physical action ; and although we shall probably never succeed in unveiling the na- ture of the peculiar 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 physiol- ogists to the proofs, contained in the following pages, of the truth of the principle, that every property, however apparently trifling or minute, possessed by any constituent of the organism, even XXIV PREFACE TO THE ENGLISH EDITION. by such as occur only in very small proportion, has its destined use and function ; and, conse- quently, that every constant difference, whether of composition, 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 phos- phate of soda and chloride of sodium which pre- vail. 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 in- gredient 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. This function, that of absorbing carbonic acid and giving it out in the lungs, is here shown PREFACE TO THE ENGLISH EDITION. XXV to depend entirely on the minute chemical charac- ters 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 tendency to acquire an acid instead of an al- kaline 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 prop- erties 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 the different systems of ves- sels, as well as the membranes and cells, must possess, in the living body, a power of selection, XXvi PREFACE TO THE ENGLISH EDITION. or, in other words, different degrees of permeabili- ty, in reference to the various substances which penetrate them by endosmose. x 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 action 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 assistance in his efforts to advance. Lastly, the present work contains some most valuable practical applications of the chemical discoveries therein detailed to an art which immediately concerns the whole of man- kind ; 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 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, Chem- PREFACE TO THE ENGLISH EDITION. XXV11 istry 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 la- borious 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 ener- gies for a long time, and unless, moreover, he had operated on a scale so large as few experimenters 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. UNIVERSITY OF EDINBURGH, 31st May, 1847. AUTHOR'S PREFACE. THE preparation of a new edition of my Animal Chemistry rendered it desirable, and even neces- sary, 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 research- es, which have led me farther than I at first anti- cipated. The questions as to the nature of the organic acid diffused through the muscular system, and that of the other substances contained in that system, appeared to me so important for the right understanding and explanation of the vital pro- cesses, that I did not feel justified in proceeding with the revisal of my work until these questions had been, at least to a certain extent, experimen- tally answered. The present little work contains the analyti- cal details of my investigation on these subjects, which, in accordance with the plan of the Animal xxx AUTHOR'S PREFACE. Chemistry, could not be introduced into that work. 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. RESEARCHES CHEMISTRY OF FOOD. SECTION I. INTRODUCTORY. On the Methods of Investigation in Animal Chemistry. IF we consider with some attention the facts which chemists have been ascertained in Animal Chemistry, we shall voted their be surprised to find how few among them there are on AnTmaf which conclusions can be securely based. The cause and'p'hysi- 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 Physiol- ogy, as De Saussure did in Vegetable Physiology, the first and most important questions as the problem of his life. Hence it comes, that in Animal Chemistry, which 1 2 METHODS OF INVESTIGATION Animal is a frontier district, belonging entirely neither to Chem- bMtoa in istry nor to Physiology, as commonly happens on the adventurers 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 expeditions 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. Conaequen- Since none of those philosophers who are called 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 fol- low the devious path of these adventurers, 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 experiment- er, 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 possession 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. Exploded er- For centuries past, men have endeavoured to dis- icai theory, cover methods of cure, or a knowledge of morbid con- ditions, by the aid of the imagination in the so-called systems of medicine ; as if it were possible, oi^even wise and judicious, to expect a true insight into these things, or to look for intellectual illumination and prog- ress from the most hazardous of all games of chance. IN ANIMAL CHEMISTRY. 3 In modern times this method has been abandoned as The chemist has no direct entirely unproductive ; but, on the other hand, men interest in -, /, Physiology commit an error not less grave, inasmuch as, instead 01 and Pathoi- acquiring by their own researches the knowledge ne- gy ' cessary for the solution of their difficulties, they leave this duty to others, who, fully occupied with the culti- vation 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 chemist are not brought into the true con- nection with the conditions which they are to explain, or with the causes which have produced these condi- tions. All the new facts daily ascertained by the Pathoiogists i 111 11- i i neglect pure chemist are regarded by pathologists as being exactly chemistry, those which are of no direct use to them, because they have no clear idea of that which they require ; be- cause they are unable to connect with these chemical discoveries any question to be solved, or to draw from them any conclusion. What an inconceivable delusion, what a confusion of Erroneous ideas must exist, when a physician thinks, that, from gar d to the the complex results of an analysis of the blood, he can connection draw a conclusion as to the nature and the cause of a icTnTamf 1 " disease, and can found on this a method of treatment, chemlstr y- 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 de- fine the notion of bad or spoiled food, in its full signifi- cation, 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 4 METHODS OF INVESTIGATION admit, that, for such an investigation, chemical knowl- edge is indispensable ; but the investigation itself has no value in reference to chemistry, and constitutes no object of research for the chemist as such. Want of mu- From this state of things, which depends on the Uon tetween want of connection between the labors of chemists and .u m physioi- tnose of physiologists, it has happened, that Animal Chemistry, during the last ten years, has gained little more than a more accurate knowledge of those com- pounds which the animal organism applies to no further purpose in its economy ; and that, at the present time, it seems as if all the wonderful properties which it ex- hibits were produced only by means of albumen, fibrine, gelatine, some cerebral or nervous matter, and a little bile. It is universally felt that we are as far chemis- from a true animal chemistry as the anatomy of the last century was from the physiology of the present day. Indeed, the animal chemistry of our time cannot be compared to modern anatomy, since microscopic re- searches have established the existence of structures which had entirely escaped the earlier investigators ; of structures, as is now known, on which alone the func- tion of those formerly observed depends, e- We know that the aliments of all plants are precise- S ' ty tne same ; but what a multitude of forms do these assume in the organisms of different plants ! The same soil on which we grow grain, beet-root, or pota- toes, 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 sul- phur and nitrogen ; in the poppy, a fat oil and a series of organic bases, containing nitrogen, but not sul- phur, which are not found in other families of plants ; in tobacco, a volatile oil, containing nitrogen, pos- sessed of basic or alkaline properties. IN ANIMAL CHEMISTRY. O These substances, so different in composition, are all derived from the same compounds, which nature sup- plies as food to all plants. It is certain that the differ- ences in the nature and composition of these products can only be determined by variations in the organiza- must depend tion of the plants which produce them ; for they are ces of organ- the visible signs of existing peculiar agencies, and plants! chemistry, which has succeeded in detecting so great a variety in these compounds, belonging only to certain vegetable families, has thus, in her department, sur- passed vegetable anatomy. 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 struc- tures and tissues are altogether unexamined ; and yet we cannot suppose otherwise than that the nature of The varied , . , n . . _ secretions of each secretion must stand m a definite relation of de- the animal pendence, in reference to its composition and its chem- ical properties, with those of the substance from which it is formed, or with those of the parts which are con- cerned in its formation. If we suppose that it is from the blood that all the constituents of the animal body are formed, this can must depend , -, i , /> A - r T-ii on similar only take place in virtue of certain forces, which be- causes; not long, not to the blood, but to the organs in which the yetstudl component parts of the blood are employed to produce them. The direction and position, the peculiar arrange- ment of the elements of the constituents of the blood in the process of nutrition, are changed according to these seats of peculiar direction in the force acting in the body, which have the same relation to the blood as the different vegetable 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 METHODS OF INVESTIGATION animal com- pounds. Agency of ferments compared with that of ordinary affinity. The trans- formation caused by a as to its chemical signification, than this, that the chief constituents of the animal body, albumen, fibrine, the gelatinous tissues, and caseous matter, when their el- ements 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 con- tact with them. That the elements of sugar, of sugar of milk, of starch, &c., in contact with the sulphurized and nitro- genized constituents of the body, or with the analogous compounds which occur in plants, when these are in a state of decomposition, are subjected to a new arrange- ment, and that new products are formed from them, most of which cannot be produced by chemical af- finities, is a fact, independent of all theory. Chem- ical affinities exert an influence on the nature of the new products, but do not determine their formation. The cause of this is obvious. When an organic sub- stance is decomposed by a chemically active body, we can, in most cases, predict the nature and the proper- ties of the new products formed by its action. If the active chemical agent be an acid, all, or a part of, the elements 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 are opposed to those of the acting body, and by which, therefore, its affinity is neutralized. In the processes called fermentation and putrefaction, the mode of ar- rangement of the elements of organic compounds is of a totally different kind ; because here it is not a foreign chemical attraction, but another cause, which determines the new arrangement. Now we know, with absolute certainty, that the products which may be gen- erated from fermentescible substances vary, as the IN ANIMAL CHEMISTRY. 7 state of the ferment^ or exciter varies. The same case- ferment va- , , . , , . . ries with the me, the same membrane, which determine the transpo- state of the sition of the -elements of sugar so as to form lactic acid, cause, in another state, the same elements to di- vide themselves into carbonic acid and alcohol, or into butyric acid, carbonic acid, and hydrogen gas. No one can fail to perceive the significance of these These princi- n i i -i. ! pies are con- facts, m respect to the understanding and the explana- cemedinthe r> P i i TP i vital P r - tion of many of the vital processes. If a change in cesses. the position and arrangement of the elementary mole- cules 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 fer- mentation, are included all those matters which consti- tute the food of man and of animals, it cannot be doubted, that the same cause plays a most important part in the vital process ; that it has a great share in the alterations which nutritious matters suffer when they are converted into fat, into blood, or into the con- stituents of organized tissues. We know, 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 com- pounds ; that their elements combine to form new prod- ucts ; and in the present state of our knowledge 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, consequently, the change of matter is The change J ' of matter is 8 METHODS OF INVESTIGATION itself a chief cause of the transformations which the constituents of the food undergo, and also a condition of the process of nutrition. We must further admit, that with every modification produced by a cause of disease 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- ner, be changed ; that the effect of a number of reme- . dies depends on the share which they take in 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 direction and force of the action taking place in the organ, which action they may accelerate, retard, or arrest. The intermediate members of the almost infinite se ries of compounds which must connect Urea and Uric 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 individ- ual member of this series, considered by itself, inas- much as it subserves certain vital purposes, must be of the utmost importance in regard to the explanation of the vital processes, or of the action of remedies. The chief constituent of bile is a crystallizable com- pound ; and no physiologist now denies, that it is in- dispensable for the process of digestion. Were we to discover in the organism certain ar- rangements by which a permanent electrical current must be determined at all points, could any one doubt that such a current must take a share in the vital pro- cesses ? Or if it were proved, that from the constit- uents of the food of all animals, among other com- pounds, organic bases are formed, which in their chem- ical nature resemble caffeine or quinine, or any other IN ANIMAL CHEMISTRY. y 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 or- ganic bodies furnished physiology with a result highly important, in order to the easy understanding of the Erroneous ,. A . . , , deductions digestive or nutritive process, by demonstrating, that from the sup- fibrine, albumen, and caseine have the same compo- fyTn compo- sition. Misled by this result, many chemists thought fibdne^aitm- that the chief problem to be solved by chemistry was Sseine" 1 to ascertain, by ultimate analysis, the composition, in * 100 parts, of all the constituents of the body ; and thus many were induced to act on each of these constitu- ents, without a more minute study of its chemical rela- tions and its properties, with alcohol, ether, and acids ; and with the aid of the known resources of organic analysis, to determine the percentage of carbon, nitro- gen, hydrogen, and oxygen. They believed that they had thus, by means of these numerical results, done a real service to physiology, although the only addition thus made to the name of the substance analyzed was an empty formula, of the accuracy of which there was ^__ no evidence whatever. Now that we have been for No progress _ _ has been ten years in possession of these formula?, every one made by the , . , , aid of mere must perceive that we have made no real progress, formulae. The cause of this is obvious to all who know the true value of ultimate analysis. Ultimate analysis is a means of acquiring knowledge, but is not itself that knowledge. Even supposing, what no one will seri- ously maintain with regard to the constituents of the animal body, that analysis had made us acquainted with the exact proportions in which their elements are united together, yet this knowledge gives us not the 10 METHODS OF INVESTIGATION The mode of least information as to the arrangement of these ele- arrangement ,, i i ^i -i of the eie- ments, or the way in which they group themselves. "ssentiaf * ie 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 period of their expulsion from the body ; and this is essen- tially the problem which Chemistry has to solve in reference to the vital process. Ultimate Ultimate analysis, by itself, has this peculiarity, that analysis is . notsuffi- in the case of very complex substances it cannot se- cure 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 individual ele- ments. 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 otherwise than in the form of water. it must be The only way to attain an accurate expression for by^Ktidy the composition of those substances, which, like the of products of . , 'iii decomposi- 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 com- pare the composition and the amount of these products with those of the body from which they have been de- rived. Example In this respect, the history of Salicine offers the from the history of most striking instance, and may serve to convince ev- Salicine. .. . ery one how little can be attained m questions of this kind by means of ultimate analysis alone. Five of the most accurate and conscientious chemists endeav- IN ANIMAL CHEMISTRY. 11 oured, 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 complex nature than animal substances), but without the slightest success, until a method, discovered by Piria, of resolving sali- cine into two other compounds, at once, and without further exertion, removed the difficuly. For each com- pound 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 com- pound from the results of its ultimate analysis. But the confidence which we repose in the dexterity of a chemist 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 chem- ists who have enriched the science with the greatest number of true formulae have only attained this suc- cess by means of their own erroneous formulae. The method just pointed out for attaining an accu- Erroneous application rate formula has not, however, escaped the notice of of this those who regard ultimate analysis as the last and highest object of a chemical investigation ; but the ut- terly fallacious application of this method has misled them into far greater errors and inaccuracies. They believed, for example, in studying a sub- Fallacious stance, that they had fulfilled all the requisite condi- ef i uations - tions when they had succeeded in representing its de- composition in the form of an equation, without caring whether the formulae which made up the equation rep- resented actual substances, or existed merely in their imagination. The following example will serve to place in a clear light what is here intended. When we dissolve uric acid in diluted nitric acid, illustration 7 from the 12 METHODS OF INVESTIGATION action of carbonic acid and nitrogen gases are given off in equal cm uric* volumes, and we obtain an acid solution, which, if neutralized by baryta, leaves, on evaporation, a mass soluble in alcohol, with the exception of the nitrate of baryta. The products of the decomposition of uric acid by nitric acid are, therefore, carbonic acid, nitro- gen, and the above-mentioned residue soluble in alco- hol. Now it is evident, that if we ascertain the weight of the uric acid and that of the residue, the compo- sition of the latter, and the proportions by weight of the carbonic acid and nitrogen disengaged, the decom- position 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 alco- hol, of carbonic acid, and of nitrogen. We- should thus have performed a series of laborious analytical operations, but no investigation of the slightest scien- tific value ; for every one knows that the product solu- ble in alcohol consists of at least five different sub- stances, 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 precipitate; with subacetate of lead, a second ; and by subsequently ad- ding 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 formula?. The equation would still have continued accurate, but it would have contained merely imaginary values, and not the for- mulae of real substances, existing independently of the numbers. Example If we compare with this example the investigation from the pro- teinecom- of the products which albumen, fibrine, and caseine pounds. IN ANIMAL CHEMISTRY. 13 yield, when acted on by strong alkalies, we shall im- mediately perceive, that the equations employed 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 utter- ly worthless for our purpose. Mulder, in his " Versuch einer physiologische Che- Mulder'* mie," Part IV. p. 321, says : " When white of egg, ec or any other proteine compound, is boiled with potash, entire decomposition takes place. The products of this representing , . , p , . the decompo- reaction are certainly not derived from the proteine sition of pro- alone, but still some of them must be regarded as con- bate, 7 stituents of that substance. These are : C. H. N. O. 2 eq. Leucine ... 24 48 4 8 Protide* .... 26 36 4 8 Erythroprotide . . 26 32 4 10 Ammonia . . . 24 8 Carbonic Acid . ' . 2 4 Formic Acid . . 2 23 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 equa- tion is founded teaches us that the whole explanation -^ quiu faliu . is utterly fallacious. For the chief product of this de- composition is a compound (possibly more than one compound) not precipitable by salts of lead ; there is * Erythroprotide is that product which is precipitated by neu- tral acetate of lead ; pro tide, that which is thrown down by ^sub- acetate of lead. 2 C10US. 14 METHODS OF INVESTIGATION 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 crystallizable body, Tyrosine (I give this name to the substance described by me in the " Annalen der Chemie und Pharmacie," Vol. LVII. p. 127), in all, therefore, five members, which are wanting in the equation. Moreover, according to the above equation, 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, imperfect no- Such explanations as the above are founded on an tions of the . . . . true province imperfect conception of the true object of a chemical of chemical . . , . research. investigation ; and when the same author, in order to support his view, that the iron in the coloring 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), as- serts, 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 con- stituents 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 statements are so many irrefragable proofs that he entertains erroneous views as to the true object of scientific researches. Without possessing the gift of prophecy, 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 formula. It will fare with these analyses as with those which he has made of vegetable mucilage, of pectine, of glycocoll * IN ANIMAL CHEMISTRY. 15 (sugar of gelatine), and other substances, for the accu- racy of which the dexterity of the chemist is for a time regarded as a guarantee, but which cease to be consid- ered accurate when the substances analyzed become the subject of more exact investigation. When such fallacious principles and methods of in- Erroneous . , , i i theories vestigation are accompanied by erroneous theoretical impede views, which, while they refuse admission to the most pl convincing evidence of the truth, are defended 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 ac- tion ; but, under such circumstances, progress is out of the question. A theoretical view in natural science is never abso- A theoretical lutely true, it is only true for the period during which trueVor the y ....," T . period. 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 includ- ed in it. But the case is very different with the so-called proteine theory, which cannot be regarded as one of the The theory ... . , . j of proteine theoretical views just mentioned, since, being supported never ex- , . . pressed the by observations both erroneous in themselves and mism- knowledge terpreted as to their significance, it had no foundation period. in itself, and was never regarded, by those intimately acquainted with its chemical groundwork, as an expres- sion of the knowledge of a given period. In the " Annalen der Chemie und Pharmacie" (Vol. Defects of LVIII. pp. 129 et seq.), Laskowski has already fully developed the analytical evidence which bears against this theory, and we may here direct attention to the defects of the theoretical notions on which it rests, or, more properly, does not rest. 16 METHODS OF INVESTIGATION Supposed The results of the ultimate analysis of fibrine, albu- "oniposition men, and caseine attracted, ten years ago, the attention aibumen%nd due to them ; since they seemed to prove that these three bodies had the same composition, the notions enter- tained concerning the process of digestion and nutrition acquired a great degree of simplicity ; these results contributed to demonstrate the value of chemical com- position as an element in the discussion of physiologi- cal questions. But this result, derived from ultimate analysis, had two disadvantages. The first was, that we were dis- posed to believe that identity of composition in the sul- phurized and nitrogenized constituents of food and those of the blood was indispensable for the understand- not necessary ing and explanation of the digestive process. But, pianation of theoretically, this identity of composition is not indis- prooiM. e pensable ; it only facilitated the investigation. When a chemical attraction causes the formation of a com- pound, it is, in regard to the chemically active, or at- tracting, body, quite indifferent 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 com- pound, it is only necessary that the attractive force should be more powerful than the forces which oppose its manifestation, 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 pro- portion with water, jujst as many liquids do, which may be mixed without forming a chemical combination ; but IN ANIMAL CHEMISTRY. 17 when the atoms of water and of hydrocyanic acid are in a certain degree of proximity, and we add hydro- chloric acid to the mixture, the mixture acts as if it were a compound of ammonia with formic acid. The hydro- chloric acid is converted into sal ammoniac, while the remaining elements unite to produce formic acid. Here the nitrogen of the hydrocyanic acid and the hy- drogen of the water, two elements belonging to two entirely distinct compounds, act, in reference to the hy- drochloric acid, as if they were combined to form the compound atom which we call ammonia. In like manner, the formation of the blood constitu- ents would have equally admitted of explanation, and would have been equally well explained, even had the food contained, instead of one sulphurized and nitrogen- ized constituent, two or three compounds, in one of which was found the sulphur, in the second the nitro- gen, arid in the third the carbon required to make up the sum of the elements. Under the influence of this idea of the necessity of Fibrine dif- . i . . , i . . , . fers in corn- identity in the chemical composition of the constituents position from of the blood and those of the food, Mulder was first caseine. ar led to assume, in fibrine, the same relative proportion of atoms of nitrogen and carbon as in albumen and caseine, in spite of the analyses of Gay-Lussac and Thenard, of Michaelis, of Vogel, and of Fellenberg, all of which indicated a larger proportion 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 preference to those which were defective. The second and far more serious disadvantage was ^ r / e ^ s the erroneous view of the chemical constitution of the ^ced from their sup- three animal substances just named, which chemists posed iden- 2* 18 METHODS OF INVESTIGATION believed themselves justified in deducing from the iden- tity of their composition in 100 parts. How are the The question, in what way the elements of fibrine, elements of n , , . these com albumen, and caserne are arranged, is one of the most ranged 8 ?"" interesting and important in Animal Chemistry. These three bodies contained (at that time this was still be- lieved in the case of fibrine) an equal amount of car- bon, nitrogen, hydrogen, and oxygen, while there was great difference in their physical properties. But we isomeric had been long familiar with groups of compounds, compounds , . , . , . , Jong known, which, with a perfect identity of composition, exhibit the most marked differences in their properties; this supposed identity of composition was not, therefore, surprising. In all isomeric substances, more exact re- search had demonstrated that their elements were dif- ferently 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 vapor, was different ; the variation in their chemical constitution corresponded to that of their physical properties. But isomer- What, now, according to these previous observations, ism was not . _ . ... . . . . supposed to was the cause of the great dissimilarity in the proper- explanation ties of the above-mentioned animal substances? If their elements were differently arranged, or the prod- ucts of their decomposition or transformation different, this formed, of course, no obstacle to the probable con- version of one into the other, of caseine or fibrine into albumen, or of albumen into caseine and fibrine, since the study of isomeric substances had taught us, that in many cases, even where the difference of chem- ical constitution was very great, such transformations of one into another actually occur. All this was left IN ANIMAL CHEMISTRY. 19 unexplored. The chemist who first entered in this field of research, which promised so abundant a har- Aiithesesub- vest, assumed, on the strength of the most defective siTppos^dTo 6 experiments, that in these three substances the four grouper eie- above-named elements were combined, exactly in the ments ' same way in all, to form a group, which group consti- tuted a distinct substance, capable of being isolated, to which the name of proteine was given. Assuming the called pro- t* i i -n teine, 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 substan- combined - . with various ces contain a certain amount of sulphur ; it was as- proportions . . of sulphur sumed, that some of them contained also a certain andphospho- amount of phosphorus ; and the variation in their prop- erties was ascribed to the presence of this sulphur, or sulphur and phosphorus. (The existence of phospho- jjjj^jj^^ rus, as an essential element of these substances, has shown to con- tain phospho- not, however, been in any way established.) In this rus - way an organic radical, or a body analogous to organic radicals, was created ; a body formed by the combina- tion of twelve hundred elementary 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 sulphur and phosphorus. To support this view, a property was imagined, which a compound of sulphur could not possibly exhibit. The sulphur, which in these compounds caused such striking differ- ences, 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 20 METHODS OF INVESTIGATION combined with it ; it dissolved in the form of sulphide of potassium and hyposulphite of potash ; the proteine was thus set free, and dissolved also in the excess of alkali ; and when this alkaline liquid was neutralized by an acid, the fundamental constituent of these animal substances, the proteine, was obtained in the form of a Supposed ox- gelatinous precipitate. The idea of the sulphide, or teine, &c. of the sulpho-phosphide, of proteine led at once to a series of oxides of proteine, to a multitude of imagi- nary substances, to which was now ascribed, as of old to phlogiston in chemical processes, the function of deter- mining 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 proper- ties of the animal substances. In the latest work of Composition Mulder above quoted (p. 316), the constitution of the of animal . substances proteine compounds is represented as follows : according to Mulder. " eq. eq. Crystal line humor contains for 15 Proteine 1 Sulphur Caseine " 10 " 1 " Vegetable gelatine " 10 " 2 " e q. Albumen of eggs " 10 " 1 " & 1 Phosphorus Fibrine " 10 " 1 " 1 " Albumen of blood " 10 " 2 " 1 We have now reached the ultimate object of this the- ory ; and the question, What insight has it afforded ? is answered by a glance at the above table. Albumen of The albumen of the blood, the properties of which blood said to * differ from ai- coincide so closely with those of the albumen of eggs, bumen of eg?s, chemically as well as physically, contains twice as much sulphur. Here similarity of properties accom- panies a difference in composition ; and from this we can draw no other conclusion than this, that the sul- phur, the amount of which varies, has no influence on these properties. IN ANIMAL CHEMISTRY. 21 But what is the cause of the great difference between while fibrine the properties of fibrine and those of the albumen of competition 6 eggs ? Is it sulphur or phosphorus ? No. These sub- eL a s lbume stances contain (according to Mulder), the same quan- tities of proteine, sulphur, and phosphorus. Such is the progress which Animal Chemistry has Such views made in eleven years in regard to the chemical consti- real progress, tution of the blood constituents ; we know as 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 transforma- tion of the caseine of milk into blood utterly impossible. Any one, who will take the trouble to prepare the so- sulphur ex- called proteine according to the directions of Mulder, form'sYiTani- must immediately perceive that sulphur is contained in |^ 1 . subBtan " fibrine, albumen, and caseine in two distinct forms of combination. If we suppose these bodies to consist of several in the form ... in which it groups of atoms, of which groups two contain sulphur, occurs in cys- the action of alkalies on them points out that the sul- phur in one of these compounds exhibits the same re- lations as the sulphur in cystine ; the sulphur of this compound combines with potassium, while it is re- placed by the oxygen of the potash ; but the other compound of sulphur remains unchanged, and its sul- phur exhibits the relations of that contained in taurine. and in tau- We observe, moreover, that the former (the more easily decomposed) of these sulphur compounds preponder- ates in the albumen of the blood ; the latter in caseine. Any one who reads the note which I published thir- teen months ago in the " Annalen der Chemie und Pharmacie " (Vol. LVII. p. 133), on these questions, will admit, that it was impossible to use greater for- bearance in pointing out to the author of the pro- 22 METHODS OF INVESTIGATION. teine theory the error into which he had fallen than I then did, while I afforded him the opportunity of re- peating his experiments. The result, however, was the publication of his recent pamphlet, a work which 1 shall not further notice, preferring 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 searches 6 " investigations of Laskowski, Ruling, Verdeil, Walther, Larger and Fleitmann, that the amount of sulphur present in amount of , , , , . . sulphur pres- the blood constituents is three times, in many cases four times, as great as the apparently well-established analyses of the author of the proteine theory had in- Proteinecan- dicated. It further appears, that a body, destitute of not be ob- J ' tained by sulphur, and having the composition of proteine, is not Mulder's ' * i methods. obtained by the methods given by Mulder ; that fibrme 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 hydrosulphuric acid in the exper- iments made with the former on artificial digestion. Products of The study of the products which caseine yields when the decompo- . iiiii- j / i i_ sition of case- acted on by concentrated hydrochloric acid, ot which, and t e he blood as Bopp has found, Tyrosine and Leucine constitute the chief part, and the accurate determination of the products which the blood constituents, caseine and gela- tine, yield when oxidized,* among which the most re- markable are oil of bitter almonds, butyric acid, alde- hyde, butyric aldehyde, valerianic acid, valerohitrile. 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 wonder- * See Appendix A. CONSTITUENTS OF THE JUICES OF FLESH. 23 ful 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 chemists and of physiologists, and encourage them to direct their efforts, more than they have hitherto done, towards this department of science. SECTION II. On the Constituents of the Juices of Flesh. IT has long been known that the flesh of newly-killed Acid reaction animals reddens blue litmus paper, while nothing cer- of flesh!" 10 ' tain is known as to the nature of the free acid which causes this reddening. Berzelius, in his detailed in- vestigation of the juice of flesh, observes on this sub- ject as follows : * " When the liquid" (obtained by pressure from the Opinions of muscular substance), "out of which the albumen and the coloring 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 color. After the evaporation of this solution there is left an extract-like mass, mixed with crystals of com- mon salt, which has a strong acid reaction, and not- withstanding leaves on incineration an ash containing an alkaline carbonate, thus proving that the mass con- tained 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 there * Handbuch, Vol. IX. p. 573. 24 LACTIC ACID TILL LATELY remains in the alcoholic solution, along with tartaric and hydrochloric acids, a combustible acid dissolved. The solution is digested with finely-divided carbonate t of lead, till lead is detected in the liquid ; it is then evaporated, the lead precipitated by hydrosulphuric acid, the acid liquid boiled \vith animal charcoal and evaporated. It leaves a colorless, very acid syrup, possessing all the characters of lactic acid, but still re- taining 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, Berzelius, 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. is lactic acid Whether these statements can at the present time be regarded as proofs of the existence of lactic acid, that is, of the acid now called by that name, will be best seen from the opinions which Berzelius entertained concerning the nature of lactic acid, both at the time when his researches were made (1807), and subse- quently (1823 and 1828). Earlier and On the occasion of his report on Daniell's lampic Berzelius as acid, Berzelius observes,* " These researches render to the nature . A , , . . , , . , of lactic acid it very probable that the lactic acid, which occurs so frequently in the animal kingdom, and which I have endeavoured to prove in a former work to be differ- ent from acetic acid, is likewise nothing more than in 1807, a similar combination of acetic acid with a peculiar 1823, animal substance, which accompanies it in its salts, is the cause of the differences between these salts and * Jahresbericht, Jahrgang II. p. 72. BUT IMPERFECTLY KNOWN. 25 the acetates, and moreover prevents the volatilization 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 neutralized with caustic ammonia and heated, yields distinctly vapors of acetate of ammonia, becom- ing acid at the same time." In the seventh yearly volume of his Jahresbericht, 182*. ^Berzelius again observes, in considering Tiedemann and Gmelin's important researches on digestion, on the oc- casion of their mentioning acetate of potash as an in- gredient 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 impure by the presence of an an- imal 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, so long it is best to retain the name of lactic acid ; for if lactic acid be a chemi- cal compound of acetic acid with an animal substance, which enters into the composition of the salts, and de- prives the acetic acid of its volatility, it would be as in- accurate to call these salts acetates, as to call the sul- phovinates or nitroleucates sulphates or nitrates." In his last investigation on this subject,* Berzelius de- and 1832. scribes some experiments, from which it might be con- cluded that lactic acid contains no acetic acid, and he terminates his researches with the following words : * Annalen der Pharmacie, Vol. I. p. 1. 1832. 3 26 ACID OF THE GASTRIC JUICE. " Future investigations must be chiefly directed to as- certain, whether that which has been called lactic acid be a mixture of two acids, which resemble each other, but yet yield different salts." The true na- From these passages it is evident, that, at the time ture of lactic , . . . . . . acid only as- when chemists began to reckon lactic acid among the certained of . ,. , . , ^ , , , late years. ingredients of the fluid of the muscles, the properties of the acid now known by that name were almost entirely unknown ; so much so, that the acid discovered by Bra- connot, which is formed in rice-water and in the juice of beet-root, was considered as a peculiar acid till L. Gme- lin 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. The former It is plain that the assumption of the existence of lac- the presence tic acid in the animal body, founded, forty years ago, in the body on grounds so uncertain and variable, could no longer iufficientf* De admitted in our day, more particularly as no chem- ist, 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- nitrogenized organic acid as an ingredient of the living body, was rendered still more doubtful and improbable, especially as when the accurate investigation of urine, in which lac- it has been shown not tic acid was said to be present, had proved the absence to exist in . . urine. of it in that fluid. What is the I regarded -the determination of the nature of the gastric juice? acid diffused through the chief mass of the body as the more important, that this alone could give us an ex- planation of the nature and origin of the acid which takes a share in the digestive process. The acid of the gastric juice is not formed during digestion from the in- gredients of the food, which in themselves are not acid, but is secreted from the lining membrane of the stom- KREATINE DISCOVERED. ITS PROPERTIES. 27 ach, even in the fasting state. If this acid were an in- gredient of the blood, then it must admit of being de- tected in the blood or in some other part of the body. Several French chemists, resting their conclusions Supposed by some, on on qualitative researches, have indeed stated that the verydefec- 1^1 ...... -11 l * ve ev i~ acid of the gastric juice is lactic acid ; but the reactions, dence, to be . . , 111' p i -j lactic acid. which 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 other acids, particularly with phosphoric acid, which is never absent in animal fluids. In 1835, Chevreul described, as an ingredient of the Kreatine dis- i i , ! n i i i covered by liquid obtained by boiling flesh with water, a new sub- Chevreul. stance, under the name of Kreatine (from Kpeas, flesh), which was distinguished by its properties from all known compounds. He obtained it in very small quantity by acting with alcohol on the residue obtained by evapo- rating the soup in vacuo. The properties of kreatine, as observed by this dis- His account . of its proper- tinguished chemist, are as follows : " Kreatine is dis- ties, tinguished by the transparency of its crystals, which are right-angled prisms of mother-of-pearl lustre ; it is heav- ier than nitric acid of sp. g. 1.34, and lighter than sul- phuric acid of sp. g. 1.84. It has no action on vegeta- ble colors ; its solution in water is not precipitated by chloride of barium, by oxalate of ammonia, nitrate of silver, sulphate of copper, protosulphate of iron, suba- cetate of lead, or bichloride of platinum. 1,000 parts of water at 15 C. (64 F.) dissolve 12.04 parts of kre- atine ; alcohol of sp. g. 0.804 dissolves about ^V^h f its weight. Its solution in nitric acid, when warmed, gives off nitrous acid, and leaves, on evaporation, a resi- due, which gives a precipitate with chloride of platinum, * See Annalen der Chemie und Pharmacie, Vol. LXI. p. 216. 28 PROPERTIES OF KREATINE. and deposits small granular crystals. Kreatine dis- solves in hydrochloric acid : the solution gives, on evaporation, colorless dendritic crystals, which do not precipitate bichloride of platinum. u In its aqueous solution, kreatine is spontaneously although slowly decomposed, there is observed a dis- tinct odor of ammonia along with a heavy, mawkish smell ; the liquid loses its transparency. " When heated in a small tube, kreatine decrepitates, gives off water, becomes opaque and dull, then melts without becoming colored, and is finally decomposed, ammonia being disengaged, along with a smell of hy- drocyanic acid and phosphorus. There is condensed in the upper part of the tube a yellow vapor, partly in the liquid state, partly in the form of crystals. The carbonaceous residue is trifling, and leaves, on incinera- tion, a mere trace of ashes, which contain no chloride of sodium. " Kreatine contains water of crystallization, which is expelled by a heat of 212 ; its ultimate elements 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. 10 its nature, and shows that it cannot be confounded with that sub- stance. He adds, that kreatine, when acted on by ba- ryta, 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 en- After Chevreul had published his observations on the deavours to . 11- obtain it. occurrence of kreatine, several chemists endeavoured again to obtain this substance. Berzeiius observes on this subject, in his " Handbuch," that " After the dis- covery of Chevreul became known, I tried in vain to His opinion, prepare this substance from raw beef. Meantime I ATTEMPTS TO OBTAIN IT. 29 have had an opportunity of seeing kreatine in the pos- session of that distinguished chemist. It would appear, therefore, rather to be an accidental ingredient, the presence of which depends on peculiar circumstances in the feeding of the cattle, and which therefore is sometimes present and at other times absent. If, ac- cordingly, it should be found in the liquid in which beef has been boiled, it would evidently be the product of a metamorphosis." Wohler observes, in a note on this wshier ob- tains it. It passage, "I have obtained this substance from the isnotaiian- soup of 8 Ibs. of beef, in yellowish crystals. It is not allantoine, as I suspected it might be." Schlossberger, in his examination of the muscles of Schiossber- ger finds it in the alligator,* says, " The aqueous extract of the the flesh of flesh, heated to coagulate the albumen, filtered, and evaporated in the water-bath, yielded a brownish-yellow syrup, pretty strongly acid, with an odor of roast meat, such as is understood under the term Osmazome, as ob- tained from ordinary flesh. Hot alcohol dissolved a considerable part with a yellow color, and deposited, on cooling, small cubical yellowish crystals, which may be washed with water, or better with alcohol. Thus puri- fied, they had all the characters of Chevreul's kreatine. When heated, they become white and opaque, then melt, giving out a yellow vapor and an ammoniacal empyreumatic odor, 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 color, soon passing into brown. They dissolved in strong ni- tric acid with the evolution of yellow vapors, and the solution, when evaporated, left a white residue. The aqueous solution of the crystals is not precipitated by * Annalen der Chemie und Pharmacie, Vol. XLIX. p. 343. 3* 30 KREATINE IN THE JUICE OF FLESH. Schiossber- Results of nitrate of silver, subacetate of lead, or salts of baryta. Unfortunately the quantity 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. u it is desirable to recommence the search for this sin- gular substance, which Chevreul discovered in the soup of the Dutch Company, but which Berzelius 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 would appear, therefore, either not usu- ally to occur in the substance of the muscles, or to oc- cur in so small a quantity that it cannot be detected. However this may be, the detection of this substance, so well characterized by its tendency to crystallize 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 " previous researches in regard to lactic acid and krea- tine 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 pecu- liarities 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. after many fruitless attempts, in obtaining a small quan- tity 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 METHOD OF OBTAINING KREATINE. 31 power of crystallizing, in consequence of a change which it undergoes under the influence of the free acid present in the soluticfa, and that in this way its pu- rification arid preparation are rendered much more diffi- cult. The separation of the non-nitrogenized acid, which I soon found to be present in the juice of flesh, was at first attended with no small difficulties, and ulti- mately it is only the more exact acquaintance with the and in devis- . . . , in= simple other substances occurring in this fluid which has led methods of A i i ,1 i /> , obtaining the to the simple methods of preparing and separating constituents them, to be described in the following pages in the order in which they present themselves to the ob- server. When the finely minced flesh of newly-killed ani- Flesh ex- , . . traded by mals is extracted by water, there is obtained a red or water. reddish-colored 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 Ber- zelius has observed, coagulates first, and the liquid re- tains its red color. The albumen at first separates as Albumen and coloring mat- a nearly colorless coagulum, which afterwards collects tcrcoaguiat- . . . ed by heat. in denser flocculent masses, and the coloring matter is only separated at a considerably higher temperature. It is easy to observe the point at which the albumen has been entirely coagulated, while the red coloring matter still remains in solution. It is now only necessary to bring the liquid into actual ebullition in a silver or por- celain vessel, in order to separate the whole of the col- oring matter in the coagulated state, and we thus obtain The filtered liquid is acid. a liquid easily filtered, which reddens litmus powerful- ly. The coagulated albumen, together with the undis- solved fibrine and cellular tissue, has 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- 32 METHOD OF EXTRACTING A good press is in- dispensable. Small propor- tion of solu- ble matter in flesh. 8 or 10 Ibs. of flesh should be used. Best mode of extraction. white, of horny hardness, and the water acquires by dissolving gelatine the property of gelatinizing on cool- ing, when sufficiently concentVated. If we desire to obtain the soluble constituents of the muscular substance without great loss, and without using inconveniently large quantities of water, a good press is indispensable. We can, it is true, by the pro- cess 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 that flesh con- tains from 76 to 79 per cent, of water, and from 2 to 3 per cent, of soluble albumen, and that after extrac- tion with water there are left from 17 to 18 per cent, of fibrine and other insoluble matters, in order to per- ceive 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 aver- age, the soluble matter of 10 Ibs. of flesh, after the coagulation of the albumen and coloring matter, does not exceed 4 oz., and of this a very considerable proportion consists of inorganic salts, the phosphates being particularly abundant, while the remainder is formed of not less than five organic compounds.) Supposing that 10 Ibs. of flesh are to be operated upon, the half of this quantity is taken, and covered with 5 Ibs. of water. The mixture is carefully knead- ed with the hands, and is then pressed as completely ;is possible in a bag of coarse linen. The pressed resi- due is a second time carefully kneaded with 5 Ibs. of water, and again pressed. The fluid of the first press- ing is set aside for further operations, that of the sec- ond being used for the first 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. THE CONSTITUENTS OF FLESH. 33 and the expressed fluid serves for the second extrac- tion 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. The united liquids are passed through a clean cloth Coagulation of the albu- to separate any fragments of muscular fibre, and then men and coi- oring matter. 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 temperature till the liquid has lost its color, and the whole of the albu- min and coloring matter have separated in a coagu- lum. 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 coloring 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 moreover advisable to re- All visible fat should be re- move all visible fat as completely as possible from the moved. 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 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 albumen and Characters of the liquid fil- colonng matter, is strained through a cloth, the coagu- tered from 6 the coaau- lum pressed, and the united liquids filtered. him. The color 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 34 EXTRACTION OF THE SOLUBLE color ; while that from veal and fowl, as well as that from fish, is hardly colored. 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 evaporated. The liquid is All the different fluids obtained by the above pro- always acid. , . , . , . , cess have an acid reaction, which appears to me 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 neutralize 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 and does not whole fluid of the muscles, the mixture would retain. become neu- trai when the not a neutral or alkaline, but an acid reaction. In blood is add- . ed to it. the hare, the amount of whose blood is proportionally small, this is certainly the case. The acid li- If the clear liquid, as obtained by filtration, be con- oration be- ap centra ted over the open fire, even without being heated an?y S ieids Wll> to the boiling point, it becomes gradually darker in als ' color, 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 color 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 CONSTITUENTS OF FLESH. 35 higher temperature to which it is there exposed, passes into a dark soluble substance ; but even when this de- posit is avoided, as, for example, when the evaporation is conducted in the water-bath, the dark color infalli- bly appears. The chief cause of it, besides the tern- The acid perature, is the presence in the liquid of free acid, moved 6 r which must be removed before evaporation. To this end there is added to the liquid a concen- by the addi- trated aqueous solution of baryta, as long as it pro- ryta. duces a white precipitate. After a certain quantity of baryta has been added, the liquid becomes neutral or even alkaline ; but this must not prevent us from adding it as long as it causes the slightest turbidity in a fil- tered portion of the liquid. The precipitate thus formed consists of phosphate Phosphates of baryta, and phosphate of magnesia, and contains tated. reC1 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 ammonia ,. . P -11 * s disen- a distinct separation of ammonia observed. gaged, The precipitate from the liquid derived from the and no sul- phates are flesh of fowls dissolves in diluted hydrochloric acid found in the _ . . .... , . precipitate. without residue ; and in those cases in which sulphate of baryta remains undissolved, its quantity, compared with that of the flesh, is so trifling, that we may as- cribe with perfect certainty the sulphuric acid thus in- dicated to the mixture of a little blood. After the separation of the precipitate, which con- The filtered tains the whole phosphoric acid of the fluid of flesh, be gently the filtered liquid is divided into flat porcelain dishes, ev 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, form- ing a dark brown ring, which, on the addition of fresh 36 SEPARATION OF KREATINE. liquid, dissolves in it without perceptibly coloring it ; but in this case the color comes out when the liquid is concentrated. When the liquid from fowl's 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. In the evaporation of the same fluid from beef, there is formed, when it has acquired a syrupy consistence, a mucilaginous skin on the surface, which, when di- A skin vided in water, swells up without dissolving. In the Scales case of the flesh of the calf and of the horse, these o"atio?\ evap " skins or membranes succeed each other continually ; they may be removed as coherent membranes, and they must be taken away as often as their formation is repeated. The concen- When the fluid has been reduced to about 5 1 of its de a pa?its iquld original volume, and has acquired a thickish consist- erysta m ence, it is placed in a moderately warm situation, and left to evaporate slowly. Very soon small, distinct, short, colorless needles appear on the surface, 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 differ- ent kinds of flesh above mentioned, except that of fish, for which a modification of it is required. Modification The ^ esn ^ fis^ es ? when finely minced, cannot be "Ls h for P fi3h. P resse d ; 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 mix- ture on a funnel, and to displace the fluids by re- peated affusion of small quantities of water. The in- fusion is colorless, slightly opalescent, has an acid re- AMOUNT OF KREATINE IN FLESH. 37 action and a very marked taste and smell of fish. When heated, it yields a perfectly white, soft coagu- lum, and after the addition of baryta, when evap- orated and allowed to cool, yields a colorless jelly, in which, when allowed to rest, very distinct and regular crystals of kreatirie form after twenty-four hours. The quantity of kreatine obtained from different Proportion of kinds of flesh is very unequal. Of all kinds, the flesh different "' of fowl and that of the marten contain the most, flesh? 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 , in wild than even in animals 01 the same class. Ihe flesh of a in confined fox, fed on flesh for two hundred days in the anatomi- cal 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 ani- its amount mal stands in an obvious relation to that of fat, or to tioTtAhat" the causes which determine the deposition of fat. From f fat flesh there are often obtained mere traces of krea- tine, 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, lean Actual v m ' amount of horse, there were obtained nearly 36 grammes (555 kreatine ob- grains) of kreatine. 116 lean fowls yielded about 72 the author, grammes (1,110 grains); and 86 Ibs. of beef 30 gram- mes (463 grains). The weight of the flesh of a fowl was, on an aver- age, 203 grammes (3,134 grains, or about 7 oz. avoir- 4 38 AMOUNT OF KREATINE IN FLESH. dupois) ; that of wild foxes weighed from 2 to 2-|- Ibs. (Hessian).* Kreatine I have found, as already stated, kreatine in the flesh the n higher of the ox, sheep, pig, calf, roe-deer, hare, marten, aSai3 0f ^o x ? red deer, common fowl, and fish ; and as it can- not be doubted that the crystals obtained by Schloss- berger from the flesh of the alligator were also krea- tine, it may fairly be concluded that this substance is an ingredient of the muscles of all the higher class- es of animals. u is not to be I have not beeen able, by the same process, to de- toain, 'liver, tect kreatine in the substance of the brain, of the liver, or kidneys, * i i i i , i i but the heart or of the kidneys ; but it is present in abundant quan- contains it. , , ,1 i /> , i 1 ^ tity m the heart of the ox, so that this organ is es- pecially 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 sub- Peculiarities stance of the brain is rubbed with barytic water to a vestigation thin emulsion, passed through a fine hair-sieve, and in the brain , . ... , and liver. heated to boiling, there is obtained a coagulum, in * Note by the Editor. The figures in the text, when re- duced 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 3 Ihs., 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, consid- erable 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. 39 which is contained 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 subse- quent 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. Kreatine. The crystals of kreatine, obtained as above de- Purification i i , ,. of kreatine. scribed, are separated from the mother liquid by a filter, washed first with a little water, then with alco- hol, and dissolved in boiling water. If the solution should be colored, some animal charcoal (from blood) is added, and a very small quantity is sufficient to give a liquid which, when filtered, is colorless and limpid, and which, on cooling, deposits the kreatine in perfect- ly pure crystals. If the phosphoric acid has not been entirely removed by means of baryta, then the original crystals are mixed with phosphate of magnesia, of which the greater part is left behind on recrystallization ; but a small portion dis- solves and is deposited along with the crystals of kre- atine. 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 dissolved. The crystals of kreatine are colorless, perfectly Description transparent, and of the highest lustre ; they belong to tais. e rys the klinorhombic system, and form groups, the charac- ter of which is exactly similar to that of sugar of lead. At 212, the crystals become dull and opaque, with loss of water. 0.485 gramme of crystallized kreatine lost, at 212, Analysis of kreatine. 0.059 gramme of water = 12.16 per cent. 0.3582 gm. of crystallized kreatine lost, at 212, 0.044 gm. of water = 12.28 per cent. 40 ANALYSIS OF KREATINE. 0.5835 gm. of crystallized kreatine lost, at 212, 0.0705 gm. of water = 12.08 per cent. 0.603 gm. of crystallized 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 crystallization. The combustion of dried as well as of crystallized kreatine with oxide of copper yielded a gaseous mix- ture, which contained, for 388 volumes of nitrogen, 1,036 vol. of carbonic acid. Hence kreatine 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 crystallized creatine yielded 0.6764 gm. of carbonic acid. (The water was lost in this analysis.) 0.5830 gm. of crystallized kreatine yielded 0.693 gm. of carbonic acid, and 0.388 gm. of water. 0.545 gm. of crystallized kreatine yielded 0.658 gm. of carbonic acid, and 0.367 gm. of water. 0.2884 gm. of crystallized kreatine yielded 1.300 gm. of the double chloride of platinum and ammoni- um, = 28.32 per cent, of nitrogen. These analyses yielded, for 100 parts of kreatine : I. II. III. Carbon 32.77 32.91 32.4 It Nitrogen Hydrogen Oxygen . 23.32 u (C 28.32 733 31.44 28.32 739 31.88 100.00 100.00 * The 2d tube gave for 89 vol. nitrogen 217 vol. carbonic acid. 3d " 64 " 156 4th " 78 " 219 " 5th " 77 " 224 " 6th 80 " 220 Total " 388 " 1036 t In combustion with chromate of lead, it is well known that ANALYSIS OF KREATINE, 41 corresponding to the formula, 8 eq. Carbon .... 48 32.22 Formula. 3 eq. Nitrogen .... 42 28.19 11 eq. Hydrogen .... 11 7.38 6 eq. Oxygen . . . . 48 32.21 Atomic weight of crystallized Kreatine 149 100.00 0.3145 gm. of anhydrous kreatine yielded, when Anhydrous burned with oxide of copper, 0.4195 gm. of carbonic acid, and 0.197 gm. of water. 0.4085 gm. of anhydrous kreatine, burned with chro- mate 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 .... 696 6.96 Oxygen 24.75 23.72 100.00 100.00 corresponding to the formula, 8 eq. Carbon . . . - . 48 36.64 its formula. 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 crystallized kreatine corresponds, therefore, to the formula, 1 eq. anhydrous kreatine . .131 87.92 Formula of 2 eq. water .... 18 12.0b the crystals. 149 100.00 If we compare the formula of kreatine with that of Kreatine and . glycocoll. the formation of nitrous acid is unavoidable, and the excess of carbon in the above analysis arises, no doubt, from a small quantity of nitrous acid which had escaped the reducing action of the metallic copper in the anterior part of the tube. 4* 42 RELATIONS OF KREATINE. glycocoli (sugar of gelatine), it appears that crystal- lized kreatine contains the elements of 2 eqs. glycocoll == C 8 N 2 H 8 Oe -f- 1 eq. ammonia = N Hs C 8 N 3 HU Oe * Kreatine dissolves easily in boiling water, and a solu- tion saturated at 212 forms, on cooling, a mass of small brilliant needles. From a diluted solution it crys- * Kreatine contains the elements of the Lactamide of Pelouze, and Urea, as Liebig has suggested in a letter to Gay-Lussac, which was published in the " Comptes Rendus " of last year. Kreatine. Lactamide. Urea. C 8 HH N 3 O 6 = C 6 H 7 N O 4 + C 2 H 4 N a O 2 . Lactamide is lactic acid or lactic sugar in which one atom of oxygen has been replaced by an atom of amidogen. Lactic acid. Lactamide. C 6 H 5 O 5 O -f N H 2 = C 6 H 7 N O 4 . Lactamide contains the elements of glycocoll and oxide of methyle. Lactamide. Glycocoll. Oxide of Methyle. C 6 H 7 N O 4 = C 4 H 4 N O 3 -f C 2 H 3 O. Glycocoll has been resolved by a current of electricity into ammonia and aconitic acid (?). Glycocoll. Ammonia. Aconitic Acid. C 4 H 4 N O 3 = N H 3 + C 4 H O 3 . Kreatine may be considered as having the elements of urea, oxide of methyle, aconitic acid, and ammonia. Kr^ine. Urea. C 8 Hn N 3 O 6 = C 2 H 4 N 2 2 -j- C 2 H 3 O + C 4 H O 3 4- N H 3 . Urea with two atoms of water contains the elements of car- bonic acid and ammonia. v Urea. C 2 H 4 N 2 2 4- 2 H O = 2 C 2 4- 2 N H 3 . These relations are interesting to contemplate, when we recol- lect that kreatine, milk sugar, urea, carbonic acid, ammonia, and glycocoll, as abenzoate in the form of hippuric acid, are found in the liquid excrements of man. E. N. H. PROPERTIES OF KREATINE. 43 tallizes very slowly, in somewhat large crystals, 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 weak- er 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 kreatine contains a trace of foreign organic matter, it decom- poses very readily, as Chevreul observed. Mouldy veg- etations appear, and the liquid acquires an offensive, nauseous odour. No quantity, however large, of kreatine can destroy Kreatine is V _ b J neither acid the acid reaction even of the weakest acids ; it possess- nor basic, es no basic characters. It dissolves easily with the aid of heat in barytic water, and crystallizes from it unchanged. The crystals which are deposited contain no baryta, and all the baryta in the solution is precipi- tated by carbonic acid. But when boiled with baryta water, kreatine is decomposed ; ammonia is disen- gaged ; 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 color of hyperoxide of lead is not changed, not even when boiled ; the crystals of kreatine deposited in cool- ing are free from oxide of lead. A solution of hyper- manganate of potash, in which kreatine is dissolved, 44 KREATININE. only loses its red color by long digestion with the aid of heat, without perceptible disengagement of gas. The liquid now contains no kreatine, and gives on evapora- tion white crystals ; while the potash is found partly combined with carbonic acid. Action of The action of strong mineral acids is very remarka- kreatine. ble. A solution of kreatine, to which, while cold, hy- drochloric acid is added, gives by spontaneous evapora- tion crystals of unchanged kreatine. But when heated with strong hydrochloric acid, a solution of kreatine no longer yields crystals of that substance. The same re- sult is obtained with sulphuric, phosphoric, and nitric acids. When kreatine is dissolved in one of these acids, and the solution gently evaporated, crystals are obtain- ed, which are very soluble in alcohol, a property not belonging to kreatine. These crystals contain a por- tion of the acid employed, in a state of combination. Kreatinine. There is formed, in this reaction from kreatine, by a transformation of its elements, caused by contact with strong mineral acids, a new body of totally different chemical properties, a true organic alkali, which I shall call kreatinine. Kreatinine. Formation of When crystallized kreatine is exposed, in the drying kreatinine, . . , by means of apparatus described by me, to a current of dry hydro- acid C C chloric acid gas, at the temperature of 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 ap- pears as if kreatine, under these circumstances, could absorb no hydrochloric acid, this conclusion is at once found to be erroneous, because during the whole con- tinuance of the experiment water is seen to pass ofT, till the weight of the apparatus becomes constant. If an- KREATIXINE. 45 hydrous kreatine be used for this experiment, an in- crease 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 ob- tained, when kreatine is covered with concentrated hydrochloric acid in a porcelain dish, and the solu- tion evaporated in the water-bath till all uncombined hydrochloric acid is dissipated. When kreatine is mixed with diluted sulphuric acid or by means (for 1 part of kreatine, 1 part of an acid, composed of acid" P " 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 ob- tained. When carbonate of baryta is added to a boiling Separation of aqueous solution of the sulphate of kreatinine, till no from the sui- more effervescence ensues, and the liquid has an alka- p line reaction, sulphate of baryta is deposited, and pure kreatinine remains in solution. From the hydrochlorate the base is obtained, when and from the J ... hydrochlo- the aqueous solution of the salt is boiled with hydrated rate, oxide of lead. The hydrochlorate is dissolved in from 24 to 30 parts of water, the solution heated to boiling in a porcelain vessel, and hydrated oxide of lead sus- pended 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 at which the liquid, no matter how much di- 46 PROPERTIES OF KREATININE. luted, 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. Purification Should a trace of oxide of lead be dissolved or sus- of kreatinine. . pended in the filtered liquid, it is easily removed by means of a little animal charcoal. This process de- pends on the conversion of the chloride of lead into a basic compound with oxide of lead, which is as insolu- ble in water as chloride of silver. The solution of kreatinine thus obtained is entirely free from chlorine, and yields, as does also the solution prepared from the sulphate by baryta, on evaporation, 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 solu- tion 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. Description The crystals of kreatinine belong to the monoklino- tais. he rys metric system, and are formed by the prism oo P, the basic terminal face o P, and klinodiagonal terminal face oo P QO . The orthodiagonal is less than the klinodiag- onal. The angle o P : QD 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 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 * The cry stall ometric measurements given in this work have been made by Dr. Kopp. PROPERTIES OF KREATININE. 47 i 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 reddened litmus paper, and a crystal, laid on moist turmeric pa- per, causes a brown stain at the point of contact. Kreatinine dissolves in boiling alcohol, and crystal- lizes on cooling. 1,000 parts of alcohol at 60 dissolve 9.8 parts of kreatinine. In its chemical character, kreatinine is quite analo- Kreatinine i* analogous to gO US to ammonia. ammonia. A moderately concentrated solution of nitrate of sil- its action on . . . iii i n nitrate of sil- ver, when kreatinine is added to it, instantly forms a V er, mass of small white needles, which are very soluble in hot water, and crystallize from it unchanged on cooling. They are a basic compound of kreatinine and nitrate of silver. In a solution of corrosive sublimate, kreatinine causes on corrosive .... . sublimate, at once a white curdy precipitate, which, in a few min- utes, changes to a mass of slender transparent colorless needles. In a neutral aqueous solution of chloride of zinc, on chloride of kreatinine causes instantly a precipitate formed of crys- talline grains, appearing under the microscope as round masses, formed of very small needles concentrically grouped. Kreatinine expels ammonia from ammoniacal salts, on salts of and forms with salts of oxide of copper crystallizable JSu^Tsaits double salts of a fine blue color. of copper, Bichloride of platinum, when hydrochlorate of krea- O n bichloride tinine is added to it, causes no precipitate if the solution of plat is diluted ; but on evaporation in a gentle heat, there are formed deep yellow transparent crystals of consid- erable size, very soluble in water, less so in alcohol. A solution of kreatinine, to which bichloride of plati- num and hydrochloric acid have been added, yields, 48 COMPOSITION OF KREATININE. when evaporated, the same compound, which is a double salt analogous to the double chloride of plati- num and ammonium. The composi- The composition of kreatinine is easily deduced tion of krea- f , . r* , ^ , *> - * tiuine de- irom the action or hydrochloric acid gas on kreatme. duced from /\ ei-we (* i its formation. 0.5/75 gm. of kreatme in crystals increased in 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 exper- iment implies, that, for 24.68 parts of hydrochloric acid absorbed, an equal or very nearly equal weight of wa- ter has been expelled. Now since crystallized kreatine, when heated alone to 212, loses 12.08 per cent.' of water, it is evident that twice this quantity has been expelled, because oth- erwise, when 24.68 per cent, of hydrochloric acid had been absorbed, the weight must have increased. Since, moreover, 1 eq. of hydrochloric acid weighs 36.5 (H = 1) and that weight corresponds to 4 eq. of wa- ter, it follows that for 1 eq. of hydrochloric acid ab- sorbed, 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 circumstances, 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 atiSnc? loses action of mineral acids, depends, therefore, on the sep- ter? 8 L aration of 4 eqs. of water. If we subtract these from the formula of crystallized kreatine, the composition of kreatinine in 100 parts is as follows : ANALYSIS OF KREATININE. 49 Formula, 8 eqs. Carbon = 48 3 eqs. Nitrogen = 42 7 eqs. Hydrogen = 7 2 eqs. Oxygen = 16 42.48 37.17 619 14.16 Atomic weight of ) Kreatinine .... 5 In accordance with this theoretical result, there were Analysis f obtained by combustion with chromate of lead the fol- lowing 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 nitrogen gas, there were found 1,132 vol. of carbonic acid.* According to this analysis, kreatinine contains Carbon . . . 42.54 Nitrogen . . . 37.20 Hydrogen . . . 638 Oxygen . . . 13.88 100.00 If we compare with the formula of kreatinine that Kreatinine of caffeine (theine), it appears that kreatinine contains andcaflfelne - the elements of 1 atom of caffeine -j- 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 Cs Na HT O 2 = 1 at. Kreatinine. N. CO52. * The 2d tube yielded 75 for 187 3d u 77 it 197 4th it 79 it 207 5th (C 48 (C 126 6th n 70 (C 200 7th cc 85 u 215 N : C O 2 = 3:8 434 u 1132 5 50 KREATINE AND KREATININE ARE Kreatine and Kreatinine, constituents of human urine. The com- If we compare the results of the analysis of kreatine pound discov- , , . . . , , ered in urine and kreatinme with the composition of the substance fe r e } " discovered three years since by Pettenkofer * in human urine, and analyzed by him, we perceive at once, that both kreatine and kreatinine must stand in a definite relation to that body. Pettenkofer found that this sub- stance, when burned, yielded a gaseous mixture, con- taining, for 8 vol. of carbonic acid, 3 vol. of nitrogen, contains the This is the same proportion as is contained in kreatine tions of car- r and kreatinine ; although, on the other hand, he found bon and ni- . . . , . . . . trogen as a variation in the proportion of hydrogen and oxygen. kreatinine! The substance from urine contains 1 eq. of water less than anhydrous kreatine and 1 eq. more than kreati- nine. Although I had no reason to doubt the accuracy of Pettenkofer's analysis, yet I considered it desirable to compare the properties of the substance from urine with those of kreatine and kreatinine. pettenkofer'a According to Pettenkofer's process for its prepara- tion, fresh human urine is neutralized with carbonate of soda, evaporated till the salts crystallize out, then extracted by alcohol, and mixed with a concentrated 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 chlo- ride of zinc and a crystallizable 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 alco- holic solution deprived of baryta by sulphuric acid, and the liquid, which now contains hydrochloric acid, sul- * Annalen der Chemie und Pharmacie, Vol. LII. p. 97. CONSTITUENTS OF HUMAN URINE. 51 phuric 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 crystal- line 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 be simpler pro- ...-- , i rrn cess proposed obtained from urine by a simpler process. 1 he urine by the au- is neutralized by milk of lime, and then solution of chloride of calcium is added as long as it causes a pre- cipitate of phosphate of lime. The liquid is then fil- tered and evaporated till the salts crystallize 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 crystallized 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 ac- quires a strong alkaline 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 coloring mat- ter and a trace of oxide of lead, and the filtered liquid is evaporated to dryness. By the process of Pettenkofer, as well as by that Pettenkofer's J r . . substance is just described, there was obtained a white crystalline a mixture of * kreatinine substance, having, in each case, the same characters, with a little . kreatine. 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 O^ ANALYSIS OF THE alcohol, one of them being easily soluble, the other very sparingly soluble, in hot alcohol. When a por- tion of the mixed substance is boiled with 8 or 10 times its weight of alcohol, either a part remains un- dissolved, or the solution is complete, but deposits crys- tals on cooling. These crystals are found to be identi- cal with the undissolved residue. When they are sep- arated from the mother liquor, and the latter evapo- rated, a new crystallization, of different form and prop- erties, is obtained. The body which crystallizes first, or remains in the undissolved residue, contains water of crystallization and has no action on vegetable colors ; 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 Analyse of indicated, that the one which first crystallized was the com- pounds from kreatine, the other kreatinine. The kreatine thus pre- pared 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 car- N. COa. * The 2d tube yielded 72 for 190 3d " 78 " 205 4th " 74 " 198 5th " 55 " 202 6th " 86 " 177 365 972 COMPOUNDS FROM URINE. 53 bonic acid were in the proportion of 280 N to 740 C O 2 , or of 3 vols. nitrogen to 8 vols. carbonic acid.* Further, 0.3767 gm. of the same body yielded 0.589 gm. carbonic acid and 0.2112 grn. water. The composition of these two substances in 100 parts Composition of the sub- is, therefore, stances from Kreatine from 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 They are the analysis of kreatine from flesh, and the analysis wi^ of the kreatinine prepared from it, it is obvious that kreatinine. they are respectively identical, and indeed no dif- ference 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 ta me to be interesting, to ascertain the influence which the putrefaction of the urine has on these substances. When putrid urine, in which, of course, all the urea in the putre- , . . . . faction of has been converted into carbonate of ammonia, is urine, the boiled with milk of lime till ammonia is no longer dis- alone disap- engaged, then filtered, evaporated to a thin syrup, and ** in this state mixed with chloride of zinc, there sep- N. c 02. * The 2d tube yielded 52 for 142 3d " 71 189 4th " 69 " 183 5th " 88 " 226 280 " 740 54 FORMATION OF PETTENKOFEtt's COMPOUND. arates in the course of a few days a considerable quan- tity of a yellow granular compound, which contains chlorine and zinc, and under the microscope cannot be distinguished from the compound formed by chloride of zinc in fresh urine. When dissolved in boiling water, and deprived of chloride of zinc and coloring matter by means of hydrated oxide of lead and blood-char- coal, the organic substance contained 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 variable 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. Formation of It is clear that if the fresh urine contain kreatinine Pettenkoler's . ... . , . , , compound, in combination with an acid, and free kreatine, the kreatinine, when it is neutralized by an alkali, will be set free, and when the liquid is concentrated to ^tti of its original volume, the addition of chloride of zinc will precipitate the compound of chloride of zinc with kreatinine ; but the crystals of this substance will be mixed with those of kreatine, whenever the quantity of kreatine present is more than the liquid can retain in solution when cold. Urine is an Although the amount of kreatine and kreatinine to source"? 31 be obtained from urine is not considerable, yet I con- kreatin?ne and side r^ the preparation of these substances from urine to be more convenient, and especially more economi- cal, 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. SALTS OF KREATININE. 55 Hydrochlorate of Kreatinine. This salt, the prep- Hydrochio- 1-11 111 M i -r rateofkrea- aration of which has been already described, dissolves tinine. readily in boiling alcohol, and crystallizes from it in short, transparent, colorless prisms, very soluble in water ; it is obtained by evaporating its aqueous solu- tion 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 de- stroyed, 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, Calculated. Found. 8 eqs. Carbon . . 48 32.30 32.48 3 eqs. Nitrogen . . 42 28.11 28.27 8 eqs. Hydrogen . . 8 5.35 5.30 2 eqs. Oxygen . ... 16 10.55 10.54 1 eq. Chlorine . . 35.4 23.69 23.41 Atomic Weight . . 149.4 100.00 100.00 Chloride of Platinum with hydrochlorate of kreati- Double salt nine. A solution of hydrochlorate of kreatinine gives, Jfd^of piaiT- on the addition of bichloride of platinum, and gentle ni evaporation, aurora-red prisms of the double salt. When more rapidly formed, this salt is obtained in yellowish-red transparent grains. 0.6086 gm. of this salt, made with kreatine prepared from flesh, left after ignition 0.1858 gm. platinum. 0.8608 gm. of the same salt, prepared with Petten- kofer'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 56 SARCOSINE. sulphate of Sulphate of Kreatinine. A boiling saturated solu- tion 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 solution becomes milky, and deposits (on becoming clear) transparent, concen- trically-grouped, four-sided tables of neutral sulphate of kreatinine, the crystals of which salt continue trans- parent 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. Hence this salt consists of Calculated. Found. 1 eq. Sulphuric acid 40 24.69 24.65 f 8 eq. Carbon 48 29.63 29.33 ., tr . ! 3 eq. Nitrogen 1 eq. Kreatinine J i 8 eq. Hydrogen 42 8 25.92 4.94 25.44 5.03 [3eq. Oxygen 24 14.82 15.55 1 eq. Sulphate of Kreatinine = 162 100 00 100.00 Sarcosine. Action of When to a boiling saturated solution of kreatine we t^watefori a( ^ ten times the weight of the kreatine of crystal- kreatme. Ji z ed 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 dis- engagement 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 filtration a transparent colorless liquid, which contains caustic baryta along with a new organic base, to which I have given the name of Sarcosine. Sarcosine. The white powder remaining on the filter PURIFICATION OF SARCOSINE. 57 contains no organic matter, and is pure carbonate of baryta. By passing a current of carbonic acid gas through l \ s purifica- the liquid, and subsequently boiling, the baryta is sepa- rated from the new base, which remains dissolved ; and the solution, when evaporated, gives a syrup, which on standing consolidates into a mass of broad, colorless, transparent plates. For the preparation of pure sarco- sine, it is important to use perfectly pure baryta, previ- ously tested for, and if necessary deprived of, traces of potash, lime, chlorine, 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 reaction. The acid solution is evaporated in the water-bath, and to the syrupy resi- due 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 solu- tion 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 crys- tallizes in from 24 to 36 hours. The crystals of sarcosine are right rhombic prisms ; crystals of acuminated on the ends by surfaces set perpendicular on the obtuser angles of the prism, that is, the combi- nation oo p : P OD. Only the faces oo P had lustre enough to admit of approximative measurement; the 58 ANALYSIS OF SARCOSINE. Analysis of sarcosine. Formula of sarcoeine. angles of the prism were found = 103 and 77. Sin- gle planes of P and o P occur rarely, and then doubt- fully indicated. The crystals are colorless, perfectly transparent, and of considerable size. They are ex- tremely soluble in water, very sparingly soluble in alco- hol, and insoluble in ether. When dried at 212, they retain their original aspect ; at a somewhat higher tem- perature 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. The analysis of sarcosine gave the following results. When burned with the oxide of copper, it gave a gase- ous 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. This gives for 100 parts, 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 1 eq. Sarcosine . 89 100.00 100.00 300.00 N. CO2. * The 2d tube yielded 42 233 3d " 38 241 4th " 40 230 5th " 40 243 6th 43 252 203 1,199 PROPERTIES OF SARCOSINE. 59 The aqueous solution of sarcosine has no action on properties of vegetable colors ; it has a sweetish, sharp, somewhat 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 solu- tion 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, converting it into a semi-solid mass. A solution of acetate of copper acquires, by the addition of sarco- sine, the same deep blue color as is caused by ammo- nia, and by gentle evaporation there are obtained thin scales of the same color. When evaporated along with hydrochloric acid, sar- Hydrochio- .. 1-11- i -i rate f sar- cosine yields a white saline mass, which dissolves in hot cosine. alcohol, and is deposited on cooling in small transparent grains and needles. A solution of hydrochlorate of sarcosine, mixed with Double salt m J . . . with bichlo- excess of bichloride of platinum, gives no precipitate ; ride of piati- / n J num> but by spontaneous evaporation it soon forms flattened octohedrons of a honey-yellow color, which often ex- hibit 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 removed, and the crystals may thus be obtained quite pure. The double chloride of platinum and sarcosine, dried Analysis of the double in the air, loses, when further heated to 212, 6.7 per salt. cent, of water. 0.4544 gm. of the anhydrous salt yielded, on ignition, 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 60 SALTS OF SARCOSINE. Its formula. Sulphate of sarcosiae. Analysis of the sulphate. 89.0) 36.4 > 70.8) 196.2 In 100 Parts. Theory. Experiment. 66.55 66.40 98.7 33.45 33.60 1 eq. Sarcosine 1 eq. Hydrochloric acid 2 eqs. Chlorine 1 eq. Platinum 1 eq. of the anhydrous double salt 294.9 100.00 100.00 The loss of weight at 212 indicates that the crystal- lized salt contains 2 eqs. of water = 5.7 per cent. Sulphate of Sarcosine. The preparation of this salt has been already described (p. 57). When the resi- due, 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 colorless four- sided tables of high lustre, which can hardly be distin- guished by their aspect from chlorate of potash. They are sparingly soluble in cold alcohol, but very soluble in water, and crystallize from their aqueous solution in large feathery plates. Both the aqueous and alcoholic solutions have a strong acid reaction, so that it is diffi- cult to tell when the washing of them, to remove un- combined acid, is complete. On this account, the fol- lowing analyses of this salt have given a slight excess of sulphuric acid. 0.6928 gm. of sulphate of sarcosine lost, at 212, 0.049 gm. of water = 6.54 p. c. ; and yielded 0.5470 gm. of sulphate of baryta = 29.25 p. c. of sulphuric 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 sulphuric acid in the anhydrous salt. I. 0.3745 gm. of this last portion of sulphate of sar- cosine (= 0.2608 gm. after deducting the sulphuric acid) gave 0.3475 gm. of carbonic acid. II. 0.3388 gm. of the same salt (= 0.2389 gm. after SULPHATE OF SARCOSINE. 61 deducting the* acid) gave 0.3087 gm. of carbonic 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 car- bonic acid, and 0.138 gm. of water. If sulphate of sarcosine be analogous in composition to the sulphates of other organic bases, the anhydrous salt contains 1 eq. of sarcosine combined with 1 eq. of hydrated sulphuric acid, and therefore, in calculating the analyses, if we deduct the weight of anhydrous sul- phuric acid present, we must obtain in the remainder a formula which includes the elements of sarcosine -f- 1 eq. of water. The formula C 6 N H 7 O 4 -f- H O would yield, in 100 Formula or _ . sarcosine in P a rtS, the sulphate. Theory. Experiment. 6 eqs. Carbon . . 36 36.73 '36.34 1$569 36J28 1 eq. Nitrogen . 14 8 eqs. Hydrogen . 8 8.16 7.90* 8.16 8.25 o eqs. Oxygen . 40 ~98 The loss sustained by the crystallized salt at 212 in- dicates the presence of 1 eq. of water of crystallization = 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 Formula of 1 eq. Water 9 > lhe sul P hate - 1 el Sarcosine . . 89 1 71 ' 02 70 ' 75 '<* I eq. Sulphate of Sarcosine 138 100.00 100.00 100.00 N * 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 ex- hausting the tube previous to the combustion. 6 62 FORMATION OF SARCOSINE. I regret much that want of material prevented me from multiplying experiments with this interesting base ; but I believe that no doubt can be entertained as to its composition and its atomic weight. Formation of The formula above given for sarcosine explains its sarcosine ex- plained. production from kreatine in a satisfactory manner. If from the elements of crystallized kreatine we sub- tract those of sarcosine, there remains a formula exact- ly identical with that of urea. Kreatine con- From 1 eq. Kreatine = Cs NS Hn O& tains the ele- TA j o n TVT TT s~\ ments of sar- Deduct 1 eq. Sarcosine = Ce N HT 04 cosine and of urea. There remains 1 eq. Urea = C 2 N* H4 Oa It is consequently obvious, that, in the decomposition 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 ba- rytic water is resolved by long boiling into carbonate of baryta and ammonia with the same appearances as Urea is form- those above described ; and I have also ascertained that ed in the pro- . .. . ..,..,.. cess. urea is present in the liquid when kreatine is boiled with baryta, if examined before the whole of the kreatine is decomposed. 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 resi- due, there is obtained a crystalline mass, which, when dried in blotting paper and treated with alcohol, yields to that solvent nitrate of urea. If the alcoholic solution be heated with oxide of lead, nitrate of lead is precipi- tated, and the liquid gives, on evaporation, colorless 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, arcosine i isomeric INOSINIC ACID. 63 is dissipated in the form of the vapor of hydrated cy- anic acid. According to the formula established by the preced- Sar . t isomerc mg analyses for sarcosine, it contains the same ele- with lacta- ments, and in the same relative proportions, as the lac- with um- tamide of Pelouze and the urethane of Dumas.* But the insolubility of sarcosine in ether and alcohol suffi- ciently distinguishes it from these two compounds. Sarcosine and urea are not, however, the only prod- Sarcosine and -,., .. - , 1 1 TP Urea n0t tne ucts of the decomposition of kreatine by baryta. If only prod- water be added to the alcohol from which the sulphate of sarcosine has been crystallized, and the liquid neu- tralized by carbonate of baryta be filtered and evapo- rated to the consistence of a thin syrup, there are de- posited, long before the point is reached at which sarco- sine would crystallize, long colorless 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 residue of baryta ; they are very sol- Another sub- uble in water and alcohol, and also in 30 parts of ether ; curs ; the aqueous solution causes no precipitate in nitrate of silver, corrosive sublimate, acetate of lead, or in salts of lime and baryta. Unfortunately I did not obtain a possibly . ' . urethane. quantity sufficient for an analysis of this substance, so as to decide whether it agrees in composition with ure- thane, which it much resembles. Inosinic Acid. When the liquid from flesh, treated as formerly de- scribed, has entirely deposited the crystals of kreatine, and is somewhat further concentrated by evaporation, if alcohol be added to it in small quantities till the whole becomes milky, it deposits, when allowed to rest for * See note on p. 42. 64 INOSINIC ACID. Its purifica- tion. some days, yellowish or white granular, foliated or acic- ular 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 sub- stances, 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 magnesia ; but the chief ingredient is the potash or baryta salt of a new acid, to inosinic acid, which I shall give the name of Inosinic acid. If the quantity of baryta added has been exactly suf- ficient to precipitate the whole of the phosphoric acid, the crystals contain inosinate of potash ; and finally, if the baryta has been added in excess, they consist of inosinate of baryta, or a mixture of these two salts. To purify the acid, the deposit is dissolved in hot (not boiling) water, and chloride of barium is added to the solution. On cooling, crystals of inosinate of baryta are deposited, which, by a recrystallizatiori, are ren- dered 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 sulphuret- ted hydrogen, is generally brown and turbid, from sus- pended sulphuret of copper, but it is rendered colorless by a little blood charcoal and filtration. Prepared by either process, the solution of the ino- sinic acid has a strong acid reaction, and possesses an agreeable taste of the juice of meat. When evaporat- ed, it yields a syrup, which, after weeks, exhibits no signs of crystallization. If this syrup be mixed with alcohol, the thick, viscid fluid is changed into a hard. Its proper- INOSINATE OF BARYTA. 65 firm, pulverulent mass, of which alcohol dissolves only traces. From a concentrated aqueous solution the acid is precipitated in white amorphous flocculi. It is insol- uble in ether. The quantity of this acid at my disposal was not suf- cient for an analysis of it ; but the analysis of the ba- ryta salt is sufficient to determine the composition 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 lime, baryta. 0.565 gm. of the double chloride of platinum and am- monium = 11.370 p. c. of nitrogen. The combustion of the inosinate of copper yielded a gaseous mixture, containing for 137 vols. of nitrogen 673 vols. of carbonic acid. This indicates that ino- sinic acid contains, for 1 eq. of nitrogen, 5 eqs. of car- bon.* 0.4493 gm. of dried inosinate of baryta yielded 0.2043 gm. of sulphate of baryta = 30.07 p. c. of ba- ryta. 0.5430 gm. of dried .inosinate of baryta yielded 0.2546 gm. of sulphate of baryta = 30.75 p. c. of ba- ryta. 0.4248 gm. of the same salt, burned with chromate 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. Hence, the anhydrous inosinate of baryta contains N. CO2 * The 2d tube yielded 49 235 3d " 45 245 4th 42.5 193.5 136.5 673.5 N : C O 2 = 1 : 5. 6* 00 INOSINATES. Calculated. Found. Formula of 10 eqs. Carbon . . .60 23.96 24.46 24.80 rtrouTlXt. 2 eqs. Nitrogen ... 28 11.18 11.37 11.37 6 eqs. Hydrogen ... 6 2.40 2 64 2.59 10 eqs. Oxygen ... 80 31.95 31.46 30.49 1 eq. Baryta .... 76.4 30.51 30.07 30.75 1 eq. Inosinate of Baryta . 250.4 100.00 100.00 100:00 Formula of After deducting the baryta, the anhydrous acid com- the anhy- . . . . J J ikous acid, bined 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 equivalent acid. of water, the formula of inosinic acid will be C 10 N 2 H 7 O^doNaHedo + HO. inosinates. Inosinates. Free inosinic acid does not precipitate lime-water or barytic water ; but when these mixtures are left to evaporate in the air, there are formed trans- parent pearly scales of the inosinates of lime and bary- ta. The free acid, as well as its soluble salts, causes a precipitate in acetate of copper; the inosinate of cop- per 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 precipitate is gelatinous, of the as- pect of hydrate of alumina, soluble in nitric acid and ammonia. In the salts of lead inosinic acid causes a . white precipitate. 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 Inosinate of Potash. This salt is obtained from the baryta salt by cautious precipitation of the baryta by carbonate of potash, and also directly from the juice of flesh (see p. 64). It is very soluble in water, and crys- INOSINATES. 67 tallizes in long, slender, four-sided prisms. It is insol- uble in alcohol, and is precipitated by it, even from di- luted aqueous solutions, as a granular powder. The addition of alcohol to a concentrated solution of inosi- nate of potash causes it to become semi-solid, from the deposition of fine pearly scales. The following deter- mination of the amount of potash was made with a specimen of the salt prepared directly from the juice of flesh after the separation 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 Formula of leq. Potash . . 47.2 21.3 20.73 SftJSSl. 1 eq. Inosinate of potash 221.2 100.0 100.00 The loss of weight at 212 indicates the presence of 7 eqs. of water of crystallization = 22.5 per cent. Inosinate of Soda. This salt crystallizes in slender inosinate of needles, of silky lustre, and is extremely soluble in water, but insoluble in alcohol. Inosinate of Baryta. This salt dissolves sparingly inosinate of in cold, more easily in hot water, and is insoluble in ryla ' 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 solution, 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, 68 INOSINATES. while water at 158 dissolves 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 men- tioned. 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 crystallized 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 potash, contained 7 eqs. of water, it would have lost 20 p. c. of water. Tnosinateof Inosinate of Copper. This salt, when dried, forms a light blue amorphous powder. It is, in the common sense of the term, insoluble in water, which only dis- solves 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 insol- uble in acetic acid, easily soluble with a blue color in ammonia. inosinate of Inosinate of Silver. The gelatinous precipitate, formed by soluble inosinates in salts of silver, is some- what soluble in pure water, but less so in water con- taining 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. 67) was decomposed by hydrosul- phuric acid, and the sulphide of silver thus obtained converted into chloride of silver. INOSINIC ACID. 69 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 composi- tion 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 same portion of substance, errors of this kind are unavoid- able. I am quite aware how imperfect is the investi- gation 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 necessarily consumed in as- certaining its nature and properties. Inosinic acid appears, from its composition, to belong inosinic acid to the coupled acids. Considered as hydrate, it con- coupled acid tains the elements of acetic 'acid, oxalic acid, and urea : 1 eq. anhydrous Acetic acid . . 4 HS Os 2 eqs. anhydrous Oxalic acid . C4 Oe 1 eq. Urea . . C 2 N 2 H 4 O 2 1 eq. hydrated Inosinic acid . . . Cio Na H 7 O u When the acid is heated with hyperoxide of lead, with the addition of diluted sulphuric acid, the oxide loses its brown color and becomes white, and the fil- tered 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 evapo- ration small colorless granular crystals, which I could not further examine, on account of the smallness of the 70 KKEATININE IN MUSCLE. quantity of inosinic acid which I was able to devote to this experiment. Effect of The temperature at which the solution of the iuice temperature on the prep- of flesh is evaporated has a great influence on the aration of f inosinates preparation of the salts of inosinic acid. In many m- from the * juice of flesh, stances, when the temperature had never exceeded 212, I have obtained no trace of inosinate 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. exTs^s'TrTthe When the juice of flesh, from which the inosinates juice of flesh, have been precipitated by alcohol, is mixed 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 brown- ish-yellow color, amounting to ^th of the bulk of the other, falls to the bottom of the vessel. If these liquids are mixed by agitation, they again separate on standing. its extrac- In the heavy viscid portion, at a temperature of 23, there are soon formed a number of transparent color- less four-sided prisms, which are pure chloride of po- tassium. They melt when heated, without blackening ; their aqueous solution precipitated nitrate of silver, and gave, with bichloride of platinum, a yellow pre- cipitate ; 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 vis- cid one, and the latter mixed with its own volume of KREATININE IN THE ANIMAL ORGANISM. 71 ordinary ether, it becomes milky, and on standing, a new separation takes place. On the bottom of the vessel there collects an amber- yellow viscid liquid, from which the supernatant lighter ethereal liquid can be easily separated by decantation. The heavier consists almost entirely of lactate of pot- ash ; the lighter contains also a certain quantity of that salt, but the chief ingredient 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 con- sistence 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 so- lution 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 yel- lowish four-sided tables. By means of a little blood- charcoal and hydrated oxide of lead, they are easily rendered colorless ; 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 of platinum, yellow crystals are ob- tained, of the form and properties of the double chlo- ride of platinum 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 percentage of platinum as in the double chloride of platinum and kreatinine. A portion of the same salt, burned with oxide of 72 KREATININE IN THE ANIMAL ORGANISM. copper, yielded a gaseous mixture, containing for 3 volumes of nitrogen 8 volumes of carbonic acid.* This is the same proportion as in kreatinine. Analysis of 0.1513 gm. of the dried crystals of kreatinine, pre- from the pared directly from flesh, yielded 0.2316 gm. of car- juiceof flesh. . . j j /\ /\o/-r / home acid, and 0.0865 gm. of water. 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 or- ganism. The objection, that the kreatinine might have been formed by the action of the free acid in the juice of flesh on the kreatine, during the short heating neces- sary to coagulate the albumen, is at once destroyed by the occurrence of kreatinine in neutralized urine, and also by the fact, that kreatine may be dissolved and boiled for a long time in mineral acids of much greater concentration than the acid of the juice of flesh pos- sesses, without suffering the slightest change, simple pro- Now that the nature of this substance, which I at tractingknja- fi rg t took for a peculiar base, different from kreatine, is flesh. 6 r known, it is no longer necessary to employ the circu- itous methods which I was compelled to adopt, in order to prevent all foreign chemical action during its prep- N. * The 2d tube yielded 60 3d 66 4th 79 CO2. 156 176 211 205 N : C==3:8. 543 LACTIC ACID IN THE JUICE OF FLESH. 73 aration. 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 dis- solved, and when chloride of zinc is added to the solu- tion, 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. When the liquid from which the inosinates have Lactic acid been deposited is evaporated in the water-bath, and the ent of feefe. residue acted on by alcohol, all the lactates are dis- solved. 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 soft, semi-solid crystalline mass. The crystals which form in it con- sist of kreatine, and of the potash salt of a riitrogen- ized acid, differing in properties from inosinic acid ; they are contained in the mother liquid, the chief ingre- dient of which is uncrystallizable lactate of potash. To prepare lactic acid from this mass, it is mixed Preparation 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 crystalline 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 of an( j pur iii ca - potash is precipitated, while the lactic acid remains in iacticacid e solution. This solution is mixed with ether till no fur- ther 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 con- 7 74 LACTATES OCCUR sistence of syrup. This syrup is again acted on by a mixture of alcohol and ether, half its volume of alco- hol 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 ac- quires 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 colorless, but appear yellow from the adhering mother liquor. The mass is diluted with al- cohol, and thrown on a filter, where it is washed by cautiously 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 colored, with blood-char- coal, and evaporated, when it readily yields perfectly pure lactate of lime. * Modification From every sort of flesh, except that of fishes, lac- cess h fo?fish. tate of lime may be obtained by this process ; but for fish it is necessary to modify it. The liquid, for exam- ple, obtained from the flesh of the pike, is evaporated to a syrup, and mixed with an aqueous solution of tan- nic acid, which causes a thick yellowish- white precip- itate, 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 ob- tained, 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 gal- lic acid partly crystallizes. 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 con- IN THE JUICE OF FLESH. 75 centrated, when after a time it yields snow-white crys- tals of lactate of lime. 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 acted on by ether, pure lactic acid is dissolved, and from this any other lactate may be easily prepared. 1.276 gm. of lactate of lime lost, when heated to Analysis of the lactates 212, 0.323 em. of water = 25.3 per cent. prepared from flesh. 1.4735 gm. of lactate of lime lost, when heated 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 La Cta t e 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 7447 74.19 74.46 74^26 JhnhJ- f 1 eq. Lime 28 25.68 25.53 25.81 25.54 25.74 drous leq. Lactate of lime 109 100.00 100.00 100.00 100.00 KXMX) The crystallized lactate of lime contains Calculated. Found. 1 eq. Lactate of lime . . 109 75.18 74.7 74J2 and of the 4 eqs. Water .... 36 24.82 25.3 25.8 'J**** I eq. crystallized Lactate of lime 145 100.00 100.0 100.0 0.274 gm. 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. ANALYSIS OF THE LACTATES The anhydrous lactate of lime therefore contains Calculated. Found. Composition 6 eqs. Carbon ... 36 33.02 33.11 32.54 oflactateof 5 eqs . Hydrogen ... 5 4.59 4.66 4.70 5 eqs. Oxygen ... 40 36.71 36.58 37.11 1 eq. Lime .... 28 25.68 25.65 25.65 leq. anhydrous Lactate of lime 109 100.00 100.00 100.00 oflactateof The lactate of zinc, prepared from flesh, was also zinc. * i analyzed. 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 crystallized 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. Us formula Hence, the crystallized lactate of zinc contains * in the crys- lale 5 Calculated. Found. 1 eq. Lactic acid ... 81 58.07 57.44 1 eq. Oxide of zinc . . . 40.5 29.03 29 16 2 eqs. Water . . . 18 - 1290 13.40 1 eq. crystallized Lactate of zinc 139.5 100.00 100.00 * 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 crystallization. It is possible that this variation in the PREPARED FROM FLESH. 77 The ultimate analysis of the anhydrous lactate of in the an- hydrous zinc gives state. 6 eqs. Carbon ... 36 29.63 29.35 29.44 5 eqs. Hydrogen . . 5 4.11 4.16 4.12 5 eqs. Oxygen ... 40 32,93 33.18 33.13 1 eq. Oxide of zinc . . 40.5 33.33 33.31 ___ 33.31 1 eq. anhydrous Lactate of zinc 121.5 100.00 100.00 100.00 From the preceding analysis it evidently appears The non- that the non-nitrogenized acid occurring in the animal acid of flesh 1-1 i i i /. j MI is lactic organism is identical with the acid formed in milk acid, 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 decompo- sition.* The Inorganic Constituents of the Juices of Flesh. Chevreul has already directed attention to the very inorganic J . i i constituents large quantity of inorganic substances contained in the of the juice juice of beef. In his experiments they 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 solution, 81 per cent, were found soluble in water, and the insoluble __ residue of 19 per cent, consisted of 5.77 of phos- phate of lime and 13.23 of magnesia. It is evident that alkalic salts are the preponder- Aikaiic i salts prepon- atmg inorganic constituents of the juice of flesh, and derate in it. amount of water in these two salts depends on this, that the lactates from flesh were crystallized by slow evaporation, and not by cooling. * From the most recent researches of Engelhard and Mad- drell, lactic acid appears to be a bibasic acid. It forms an acid salt with baryta, and its formula must consequently be doubled. 7* 78 INORGANIC CONSTITUENTS Importance of the inor- ganic constit uonts. The ash of the juice of meat con- tains only alkalic phosphates and chlo- rides. that phosphate of lime is in the smallest proportion compared to those salts and to the magnesia. Now, since we may assume with a degree of prob- ability almost amounting to certainty, that, in so per- fect a machine as the animal organism, every part has its significance, I have thought it of importance to make some experiments on the nature of the miner- al acids and alkalic bases occurring in the juice of flesh, and their mutual relations, experiments which, however imperfect, may still serve as points of de- parture for future researches. The organized constituents of the body have been derived from unorganized matters, and return to the unorganized state ; and it is especially with the unor- ganized 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 ; while, on the other hand, a variation in their relative proportions enables us to infer a corresponding variation in some vital action. When the juice of flesh (extracted as formerly de- scribed, and therefore diluted with water) is evaporat- ed, even without the addition of baryta, it acquires at last, even when the temperature never exceeds 112, a brown color, and a taste of roast meat, and leaves when ignited an ash, which may be burned white, al- though with some difficulty. This ash dissolves almost entirely in water, and in this solution acids occasion no effervescence ; the ash, therefore, contains no alka- line carbonates. A more minute examination shows that it consists only of alkaline phosphates and chlo- rides. OF THE JUICE OF FLESH. 79 The precipitate formed by baryta in the juice of flesh NO sulphates in many cases dissolves entirely in diluted nitric acid ; and in those cases in which a residue of sulphate of baryta is left, its quantity is so. trifling, that, for ex- ample, in the entire flesh of a fowl or of a fox its weight cannot be ascertained. Sulphates or sulphu- ric acid are therefore not present in the juice of flesh, a fact already ascertained by Berzelius. The soluble salts obtained from the ash of the juice The different of flesh contain the different modifications of phos- p^phoric phoric acid, which are easily distinguished by their aci ' action on nitrate of silver. It is well known that common or tribasic phospho- ric acid forms three different salts with the alkalies ; two of these, in their aqueous solution, have an alka- line, the third has an acid, reaction. When a salt of phosphoric acid with 3 atoms of characters fixed base, which is strongly alkaline, is mixed with ent forms of neutral nitrate of silver, a yellow precipitate is formed, phosphates, 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 precipi- tate, and the mixture, after precipitation, is neither alkaline nor neutral, but acid. When these latter salts are ignited, they are con- verted into pyrophosphates (bibasic phosphates), which, when dissolved in water, exhibit an alkaline reaction, and give with neutral nitrate of silver a white pre- cipitate. After precipitation, the mixture is neutral. The salts of tribasic phosphoric acid with 1 atom of fixed base have a strong acid reaction. With neu- tral nitrate of silver they give the yellow precipitate 80 CHARACTERS OF THE DIFFERENT formerly mentioned, while the mixture retains its acid reaction.* When ignited, these latter salts pass into metaphos- phates (monobasic phosphates), of which the meta- phosphate of potash is not soluble in water. Meta- * The following formulae will serve to elucidate the above re- actions. 3 Meo, P Os is the neutral tribasic phosphate. The atoms of base may be all of metallic oxide, as (a) 3 Ca O, P O 5 3 Mg O, P O 5) or 3 Na O, P O 5 , or two of metallic oxide and one of water or ammonia, (6) 2 Na O, H O, P O 5 , or 2 Mg O, N H O 4 , P Os, or one of fixed base, one of ammonia, and one of water, as (c) Na O, N H 4 O, H O, P O 5 . If (a) be ignited, it remains unchanged. If (b) be ignited, the water or ammonia is driven out, and 2 Na O, P O 5) or 2 Mg O, P O 5) the bibasic phosphate or pyro- phosphate, remains. If (c) be ignited, both ammonia and water are driven out, and the Na O, P Os ( metaphosphate or monobasic phosphate, remains. (a) gives a strong alkaline reaction, a yellow precipitate with nitrate of silver, and a neutral filtrate. 3 Ca O, P Os -f 3 [AgO, N O 5 ] = 3 AgO, P Os -f- 3 [Ca O, N0 5 ]. (b) gives an alkaline reaction, a yellow precipitate with ni- trate of silver, and an acid filtrate. 2 Na O, H O, P O 5 -f- 3 [Ag O, O 5 ] = 3 Ag O, P Os -f 2 [Na O, N Os] + H O, N Os After ignition the reaction is alkaline, the precipitate with nitrate of silver white, and the filtrate reacts neutral. 2 Na O, P Os + 2 [Ag O, N O 5 ] = 2 Ag O P Os -f- 2 [Na O, N0 5 .] (c) gives an acid reaction, a yellow precipitate with nitrate of silver, and an acid filtrate. Na O, N H 4 O, H O, P Os + 3 [Ag O, N O 5 ] = 3 Ag O, P Os + Na O, N Os + N H 4 O, N Os -f- H O, N Os. After ignition, the salt gives a white precipitate with silver salt. Na O, P 0$ + Ag O, N Os = Ag O, P Os + Na O, N Os. E. N. H. MODIFICATIONS OF PHOSPHATES. 81 phosphate of soda dissolves readily in water, and gives with nitrate of silver a white precipitate, which again dissolves in an excess of the precipitant. If we compare with the characters just described Characters those of the ash of the juice of flesh, we observe the of the juice following facts. The ashes of the juice of flesh, in the case of the ox, horse, fox, arid 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 precipitation, is perfectly neutral. This proves that the ashes con- they contain . . pyrophos- tain salts of phosphoric acid, with 2 atoms (pyrophos- phatesand vrv tribasic phos- phates), and with 3 atoms (tribasic phosphates) of phates. 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 propor- tion between the white and the yellow precipitate with nitrate of silver is altered, the quantity of the yellow precipitate being increased ; but the two colors of the precipitate are constantly observed. The ashes of the juice of the flesh of fowl give a The ashes of T/T. rrn ' the juice of different result. 1 he aqueous solution precipitates m- fowl con- trate of silver purely white ; the ashes, therefore, con- tain alkalic pyrophosphates ; and when they are acted on by nitric acid and again ignited, the soluble portion still precipitates nitrate of silver only white, although an additional quantity of alkali is thus added to the phosphate originally present. From this it follows, tainpyro- that the juice of the flesh of fowl must contain a cer- ESd^meu? tain though small quantity of alkalic phosphate with p 1 atom of fixed base (metaphosphate), since, other- wise, after the action of nitric acid on the ashes, a certain quantity of phosphate with 3 atoms of fixed 82 ACIDS AND ALKALIES base (tribasic phosphate) must have been produced, and thereby a yellow precipitate must have been formed, to a corresponding extent, in the nitrate of silver. Proportion of The whole amount of alkalies, therefore, present in the phospho- the juice of the flesh of the ox, horse, fox, and 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 sufficient to convert the phosphoric acid entirely into the salt with 2 atoms of fixed base. I have mentioned in a preceding part of this me- moir, that the juice of flesh, even before all the phos- phoric acid has been precipitated by baryta, at a pe- riod, therefore, when it can contain no baryta dissolved, acquires an alkaline reaction. The organic From this it is plain, that the organic acids present juice are not in the juice, the lactic and inosinic acids, &c., taken neutralize together, are not in sufficient quantity to form neu- ' lles * tral 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 pres- ence of acid salts of the alkalies with the three acids, phosphoric, lactic, and inosinic acid. Inosinic acid constitutes too small a part of the juice to allow us to ascribe to it a perceptible share in producing the acid The acidity quality of that fluid; and this acidity depends, there- depVnd'^on 6 fore, on the presence of acid alkalic lactate and acid alkalie phosphate (phosphate with one atom of alkali) ; or > m otner words, of neutral alkalic lactate and phos- phate, along with free lactic and phosphoric acids. It is obvious, that these two acids are shared be- tween the bases present, and that the amount of free acid present must stand in a definite relation to the quantity of the bases. IN THE JUICE OF FLESH. 83 Between the two acids, so far as they are uncom- Equilibrium bined, an equilibrium is established ; the quantities of these free the free acids are proportional to their affinity or pow- er 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 pro- portion, so that a new equilibrium may be established 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 alkalic 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 corresponding quantity of phosphoric acid be set free, when the amount of lac- tic acid present is in any way increased. Now, since the quantity of phosphoric acid in the juice is sufficient to neutralize all the alkali present, white 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. The salt of phosphoric acid, which is formed when When either all organic acids are removed from the juice of flesh, acfd^f? the although neutral in composition, has an alkaline re- acid S arere C - action ; and when all the phosphoric acid is removed, SsJfue is e a i. there age left salts of organic acids, which, from the k< f presence of free alkali, also possess an alkaline re- action. 84 THE FUNCTION OF LACTIC ACID. Explanation The preceding considerations naturally lead to the of some pro- . cesses in 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, consequent- ly, 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 mus- cles, or secreted by the kidneys. If the urine of the animal were acid before digestion, it must, on the latter supposition, become, during that process, transiently neutral 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 mat- ter, and of all such substances as affect the normal qual- What pur- ity of the blood. In this point of view, the solution of pose is serv- ed by the lac- the question, u What purposes does lactic acid serve in the organism ? " is of peculiar importance. On this point I have made some experiments, which may per- haps assist us in approaching nearer to the solution. Lactic acid I have, in the first place, repeatedly endeavoured to does not r . r . . J occur in detect the presence of lactic acid in fresh urine, pos- urine. sessing the usual acid reaction. But I have not been fortunate enough, with the aid of the same process by means of which I succeeded in demonstrating its pres- ence in the juice of flesh, to detect even a trace of lac- tic 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 solu- URINE CONTAINS NO LACTIC ACID. 85 tion 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 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 di- luted with water, and acted on, when cold, with an ex- cess 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 precipi- tated no oxide of silver, and the solution thus neutral- ized 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 no instance lactate of lime. The urine of healthy men, which has an acid reac- tion, contains, therefore, no lactic acid, and no substance from which lactic acid can be formed during the putre- faction of urine.* With respect to the presence of lactic acid in alka- Jt camiot be line urine, the following experiment is sufficiently de- fheurine" cisive. Three persons, among whom were my two as- ^emaiiy en sistants, took a quantity of lactate of potash sufficient to have yielded an ounce of lactate of zinc. All the urine for the tw r o subsequent hours was collected. In each case the urine, before the experiment, had an acid re- * 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 constit- uents 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. 8 86 LACTIC ACID SUPPORTS RESPIRATION. action ; 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 impossi- ble to detect the lactic acid in this urine ; it had entirely disappeared during its passage through the blood. The lactic From this it plainly appears, that the lactic acid in acid is con- sumed in res- the organism is employed to support the respiratory process, and the function performed by sugar, starch, and in general all those substances which, in contact Function of with animal matter, are convertible into lactic acid, i^mXnge'r ceases to be an hypothesis. These substances are con- verted 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 ele- ment. When we consider that the urine of graminiv- orous 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 lymphatics (the juice of flesh) retains an Some cause acid reaction, we perceive that a cause must necessarily thlTremovai be in action at these points which prevents the removal acidaV 66 of the free acids, or, if they are removed, reproduces them at each moment of time. The blood-vessels and lymphatics contain an alkaline fluid, while the surrounding fluid, that of the flesh, is acid ; the tissue of which the vessels are composed is permeable for the one or the other of these fluids. Thecondi- Here, then, are two conditions favorable to the produc- eiectricai tion of an electrical current, and it is far from improb- present. & * able that such a current takes a certain share in the POTASH ABOUNDS IN FLESH ; SODA IN BLOOD. 87 vital processes, although its action be not always indi- cated by proper electrical effects.* I have already mentioned, that the juice of flesh, in Potash pre- . ponderatesin all animals, is particularly rich in potash, and that it the juice of contains also chloride of potassium, with only traces of chloride of sodium. Now, as every constant peculiarity in the form or in the composition of any part of the body has a significance of its own, this fact, namely, the pre- dominance of salts of potash and of chloride of potas- sium 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 pot- ash, and preponderating quantities of the salts of soda, Soda prepon- derates in the and of common salt, are present. blood. To give a specific direction to our views on the sub- Relative pro- ject of these differences, I have thought it advisable to potash and , . , , , . soda in flesh make some experiments, in which the relative propor- a 'nd blood, tions of the compounds of sodium and potassium in the blood, and in the juice of the flesh, were determined comparatively in different animals. In these determinations the phosphoric acid was pre- Method cipitated from the fluid of flesh by baryta, the filtered er liquid evaporated to dryness,and the residue incinerated. The ashes thus obtained are very fusible and of pecu- * Professor H. Buff has, at my request, constructed a pile, consisting of disks 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, indicating 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 opposite 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 perceptible degree of alkalinity. 88 PROPORTIONS OF POTASH AND SODA Kesults in the Fowl, Ox, Horse, Fox, liar character, consisting almost entirely of cyanate of potash and cyanide of potassium, 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 cyaniq acid ; a certain amount of sal ammoniac is formed, and hy- drocyanic acid is abundantly disengaged. If bichloride of platinum be now added, to separate the potash from the soda, the precipitate which is formed contains am- monium-chloride of platinum, by which the determina- tion of the potash is rendered inaccurate. It is there- fore necessary, before adding the bichloride of platinum, to evaporate the solution of the ashes in hydrochloric acid to dryness, to ignite the residue, and thus expel the sal ammoniac. In the analyses made by Henneberg of the blood 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 chloride of sodium, for 100 parts of soda, 40.8 parts of potash. The juice of the flesh of the same fowls yielded, for 3.723 gms. of double chloride of platinum and potassium, 0.374 gm. of chloride of sodium. Ox-blood gave, for 0.184 gm. of chloride of platinum and potassium, 1.133 gm. of chloride of sodium. The juice of ox-flesh gave, for 1.933 gm. of chloride of platinum and potassium, 0.2536 gm. of chloride of sodium. Horse-blood gave, for 1.351 gm. of chloride of so- dium, 0.341 gm. of chloride of platinum and potas- sium. The juice of horse-flesh gave, for 4.414 gm. of chlo- ride of platinum and potassium, 0.544 gm. of chloride of sodium. The juice from the flesh of a fox, killed in the chase. IN BLOOD AND IN FLESH. 89 gave, for 1.474 gm. of chloride of platinum and potas- sium, 0.250 gm. of chloride of sodium. The juice from the flesh of the pike gave, for 1.964 and Pike, gm. of chloride of platinum and potassium, 0.065 gm. of chlaride of sodium. 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 numbers These num- only express approximatively the proportions of potash proximative. 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 tind lymph, fluids which contain much soda. Had it been possible to obtain the juice of flesh unmixed The juice of with blood and lymph, the proportion of potash to soda possibly would have come out much higher ; so much so, indeed, soda!*'" that the conclusion 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 and The permea- qualities in the fluids circulating in the different parts of vesseisof the . r, ,, , ^ , . various fluids the organism, it follows, that there must be a very re- must be dif- markable difference in the permeability of the pari- etes of the vessels for these fluids. Were this perme- ability 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 blood of the ox 8* 90 IMPORTANCE OF CHLORIDE OF SODIUM 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 simi- ponderates . in milk. lar 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 quan- tity than in the saline constituents of blood. Accumuia- In some pathological conditions there has been ob- aclds'in ree served,* at points where bones and muscles meet, an sues. m ' 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 of the bones, is a causing the consequence of this state. It is riot improbable that the an?e P oTthe cause, or one of 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 and Mdhuntotto phosphate of soda in the blood, and that of phosphate of potash and chloride of potassium in the juice of flesh, justify the assumption that both facts are altogether in- dispensable for the processes carried on in the blood and in the fluid of the muscles. Use of salt. Proceeding on this assumption, the necessity for add- ing 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 respiratory process, inland plants It is a fact, now established by numerous analyses, that the ashes of plants, growing at a certain dis- * Schmidt, Annalen der Chemie und Pharmacie, Vol. LXI. p. 329. TO THE FORMATION OF BLOOD. 91 tance from the sea, contain no soda, or only traces of that base. The ordinary potashes of inland countries give most contain no . soda, and lit- convincing proof of this ; for they but rarely contain tie chloride any carbonate of soda ; and when a compound of so- dium 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 Oden- wald, 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 sea- The same coast, these proportions are altered. Wheat, pease, mariume dis- . and the other leguminous plants, in the Netherlands, soda^ndlx)" contain phosphate of potash, and also phosphate of ash> soda, the phosphate of potash, however, always pre- dominating. This is the case even in sea plants, living in a medi- Even sea um which contains, compared with its amount of soda urn^mS? or sodium, a mere fraction of pota'sh. All sea plants sodT. h l contain much more potash than soda. In respect to these two bases, therefore, the food of animals is not in all places of the same quality or com- position. An animal, feeding on plants which contain phos- Necessity of phates of other bases, along with some compound of sodhmftoan- i T i i i i i i t e> imals feeding soda or sodium, produces in its body the phosphate 01 O n inland soda indispensable to the formation of its blood. But plar an animal, living inland, obtains in the seeds, herbs, roots, and tubers which it consumes, only salts of pot- ash. It can produce, from the phosphates of lime and magnesia, by decomposition with the salts of potash, only phosphate of potash, the chief inorganic constit- uent of its flesh ; but no phosphate of soda, which is a 92 USES OF THE PHOSPHATE OF SODA compound never absent in its blood. Whence, there- fore, does it obtain this phosphate of soda ? The true Action of answer to this question is given by a study of the ac- 'tashor? tion of phosphate of potash on chloride of sodium. sodium 6 Phosphate of potash, with 2 atoms of potash (tribasic phosphate of potash, with 2 atoms of fixed base and 1 !2 1C O ) J , is deliquescent, HO* hardly crystallizable, and has a very feeble alkaline reaction. When we supersaturate phosphoric acid (tribasic) with potash, and evaporate to crystallization, a salt is deposited, which has an acid reaction = P O 5 < > . There is no salt which loses half the amount of base it contains so easily as the phosphate of potash. If phosphoric acid be neutralized with potash, and chloride of sodium added to the solution, and the whole left to spontaneous evaporation, a phosphate crystallizes, which contains both potash and soda / ( Na )\ I the tribasic salt P O 5 J K O \ 1 , while chloride of V i HO) / potassium is found in the mother liquid. It is obvious, that phosphate of potash is decomposed when in contact with chloride of sodium ; part of the potassium combines with the chlorine, while the sodi- um replaces it in the phosphate, phosphate of soda being produced.* * It is evident that the tribasic salt above mentioned, r Na O } P Os < K O > may equally well be represented as a double salt, (HO) composed of phosphate of soda and phosphate of potash. W. G. CONTAINED IN THE BLOOD. 93 In this way we can understand the formation of phosphate of soda in the body of an animal, which ob- tains in its food, along with phosphate of potash, or earthy phosphates and salts of potash, no compound of soda except chloride of sodium ; and when, in inland countries, the food does not contain common 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 pro- duced, in this case, by mutual decomposition with phos- phate of potash or with earthy phosphates, the phos- phate of soda of the blood. That phosphate of soda is indispensable to the nor- The phos- mal constitution of the blood, and that the processes fn^he^bioo which go on in that fluid cannot be replaced by phos- phate of potash, seems to me to be an opinion 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 quality of the blood has a very decided share in its property of importance thus taking up carbonic acid ; as, on the other hand, hig^Se^rue the chemical nature of the compound, on which the afkaUnuV^f alkaline reaction of the blood depends, exerts the most lhe marked influence on the power of the blood again to give off the carbonic acid which it had absorbed. It is known that freshly drawn blood, by mere agita- Relation of . ,-! i -i TV / i j blood to car- tion with air, by passing through it a current of hydro- bonicacid gen gas, or in the vacuum of the air-pump, gives off g carbonic acid. From the experiments of Scheerer, at which I 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, Experiments absorbs nearly twice its volume of carbonic acid, that is, as much more as the same bulk of water can ab- sorb at the same temperature. The greater absorbing 94 RELATION OF BLOOD AND SERUM power of the serum is determined by a chemical at- traction, by a substance which has an alkaline reac- tion. In fact, it is observed, that, when this alkaline reaction is destroyed, when acetic acid is added to the blood saturated with carbonic acid, the excess of car- bonic acid is at once given off. Bat 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 cir- cumstances, not more than half its volume of carbonic acid can be obtained from blood. The serum of Had the greater absorptive power of the serum of blood con- . . tains no blood for carbonic acid been dependent on the pres- carbonate . , . , . of soda. ence of carbonate of soda, and its conversion into bi- carbonate of soda, this would imply that the blood must contain at least its own volume of carbonic 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 car- bonic 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 vol- ume of carbonic acid equal to twice the volume of the blood. The acid would, in fact, disengage three vol- umes of carbonic acid, one of which is retained by the liquid. In the experiments of Scheerer, serum of blood, which 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. TO CARBONIC ACID GAS. 95 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 carbonic acid.* When 2,000 cubic centimetres of ox-blood, mixed The author's . experiments with twice their volume of water, are heated to boil- to prove this. ing, and the coagulum pressed out, we obtain about 2,000 c. c. (^d of the whole liquid) of an alkaline liquid. If the alkaline reaction of this liquid arises from car- bonate of soda, these 2,000 c. c. must contain Jd of the whole carbonate of soda contained in that volume of blood. When concentrated to \d by evaporation, this liquid must contain exactly as much, if concentrated to Jth, twice as much, to ^th, four times as much, and to \th, eight times as much, &c., carbonate of soda as an equal volume of blood. Now I have concentrated this liquid to ^th of its Highly cou- . . . centrated se- volume, in which state it must, on the supposition for- rum absorbs merly mentioned, contain 166 times as much carbonate acid. of soda as an equal volume of blood, if that salt were an ingredient of blood. When brought in contact with * 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 disen- gaged, 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, 235 58 (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. 96 THE ABSORBENT POWER OF SERUM carbonic acid, this concentrated 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 orig- inal volume of carbonic acid, of which d would be re- tained by the liquid. From 20 c. c., therefore, of the but does not concentrated liquid, there should have been obtained give off a trace when 40 c. c. of free carbonic acid. But this liquid, when acids are . .77 / added to it. acted on by acids, gave off no appreciable, trace of car- bonic 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 7.5 cubic is expelled. But even on the most favorable supposi- rumcanno^" tion, that is, if we admit that the liquid is saturated thanT5ths re with carbonic acid, it is obvious that no more carbonate carbonate of f s d a can be contained in it than corresponds to the "^ volume of carbonic acid required to saturate the jj^th part of the volume of the serum. This amounts, for 1000 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 fths of a grain. butitabsorbs The serum of blood absorbs, therefore, 166 times thneTmore more carbonic acid than could be absorbed by the very tbanthL aCld largest proportion of carbonate of soda which it can be could* 16 supposed to contain ; and consequently the carbonate of soda, if it be present at all in the liquor sanguinis, can have but a most insignificant share in the absorp- tive power of that fluid for carbonic acid. This depends As the study of the serum and the analysis of the phate 6 of so- ashes of blood prove, the alkaline quality of the blood depends on the presence of phosphate of soda. In- deed, it may well be asked, from what source can car- DEPENDS ON PHOSPHATE OF SODA. 97 bonate of soda, if we suppose it to be present, be de- . rived, in the blood of a man living on bread and flesb, 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 ? * There is no known salt the chemical characters of Remarkable which approach more closely to those of the serum of phosphate of blood than the phosphate of soda ; there is none more fitted for the absorption and entire removal from the or- ganism of carbonic acid. This salt behaves towards carbonic acid exactly as neutral carbonate of soda ; its aqueous solution absorbs carbonic acid gas with the same facility, but with this difference, however, that it not only , . n . i'ii absorbs, but under the influence of the same causes which decom- also gives oti; pose the neutral carbonate and the bicarbonate of with great fit- soda, this solution gives off the carbonic acid which it has absorbed much more easily, and also more com- pletely, since it does not, like soda, in its conversion from bicarbonate 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 (P O 5 , 2 Na O, H O), 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.t * 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 phosphates 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 two atoms of fixed base (P O 5 , 2 Na O, H O). t A solution of phosphate of soda, saturated with carbonic 9 98 IMPORTANCE OF THE PHOSPHATE By simple agitation with air, or by diminution of the atmospheric pressure, fds of the absorbed carbonic acid are given off at the ordinary temperature ; by con- tact with fresh carbonic acid, these ds are immedi- ately again absorbed.* acid, may be recommended as one of the pleasantest saline pur- gatives. Experiments. * A solution of 1 part of dry phosphate of soda, P Os,2 Na O, H O, in 100 parts of water, when agitated with pure carbon- ic 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 ] 14 112 100 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 treat- ed 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 a5 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 99 116 100 vols. 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 un- der a pressure of 2"'. When again placed in contact with car- bonic acid, it absorbed : I. II. III. Solution, c. c. . . . . 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. 99 By the spontaneous evaporation in the air of the Uses of the /. t i i phosphate of solution of phosphate of soda, saturated with carbonic soda in blood. acid, the whole of the carbonic acid is given off, and the phosphate is left, with all its original properties, in- cluding its alkaline reaction. When carbonic acid is taken up by the blood, there Action of is established between the phosphoric and carbonic acids on the blood. 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 circumstances more favorable to the separation of one or other of the two acids. If we assume, that the carbonic acid seizes a portion of the soda, we may imagine that the phosphoric acid, previously combined with this portion of base, is ex- pelled from the place it originally occupied, 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 car- bonic acid for soda), suffices to displace the carbonic acid, and to reproduce the original compound. Agita- tion with air ; the spontaneous evaporation of the water in which the compound is dissolved; the dimi- nution of the atmospheric pressure ; all these causes, which have no effect on neutral carbonate of soda, pro- duce decomposition, and cause the separation of the 100 PROPORTIONS OF LIME, MAGNESIA, JcC., IN FLESH. carbonic acid, taken up by the phosphate of soda in The amount the blood. In this manner, the amount of carbonic ef carbonic . acid in the acid in the blood is kept at a constant value. If more Wood is kept . . . uniform. 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 other- wise 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 the lies, and salts influence which alkalies, salts, and mineral acids ex- on respira- tion, ert 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. flesVcon- f ^ ^ as a ^ rea( ^y been pointed out, that in the juice of mtie lime ^ es ^ t ^ le amount f phosphate of lime, compared 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 millegrammes (1 millegramme = T ^th 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. Proportion of The juice of fowl's flesh was precipitated by baryta, magnesia in the precipitate dissolved in hydrochloric acid, the bary- fowi J . UK ta separated by sulphuric acid, and 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. Proportion The proportion of the phosphoric acid combined of alkaline , , . , .1 phosphates, with alkalies to that united with magnesia, in the PRACTICAL APPLICATION OF THE RESULTS. 101 juice of ox-flesh, was determined in the following manner. The precipitate formed by baryta contains all the phosphoric acid, partly combined w r ith baryta (as P O 5 , 3 Ba O), partly with magnesia (as P O 5 , 3 Mg O). 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 pre- cipitate contained the phosphoric acid originally com- bined with alkalies, and when mixed with sulphate of magnesia yielded a new precipitate of the same double phosphate of ammonia and magnesia. 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, com- bined with alkalies, chiefly potash. In another ex- periment the proportion was found to be as 1 to 3.2. SECTION III. Practical Application of the Results of the Foregoing Investigation. WITH reference to a future chemistry of alimen- Effector tary substances, it appears from these researches, that flesh? by the boiling of flesh an essential change in its com- position is effected. According to the duration of the boiling, and the amount of Water employed, there takes place a more or less perfect separation of the soluble from the insoluble constituents of flesh. The water in which flesh has been boiled contains soluble alkaline 9* 102 FLESH COMPLETELY EXTRACTED phosphates, lactates, and inosinates, phosphate of mag- nesia, and only traces of phosphate of lime ; the boiled flesh contains chiefly, with the fibrine, &c., the insolu- ble inorganic constituents, phosphate of lime and phos- phate 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 condition, none of the constituents of raw flesh ought to be with- drawn from it during its preparation for food. If its composition be altered in any way, if one of the con- stituents which belong essentially to its constitution be removed, a corresponding variation 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. It follows from this, that boiled flesh, when eaten without the soup formed in boiling it (the louilli with- out the bouillon), is so much the less adapted for nu- trition, the greater the quantity of the water in which it has been boiled, and the longer the duration of the boiling. When finely chopped flesh is extracted with cold water, it loses the whole of the albumen contained in it. The fibrinous residue, after being well washed with cold water, if boiled with water is found to be perfectly tasteless ; it is cleai; 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 soluble constituents of the juice, which have undergone a slight change under the influence of the higher temperature. Flesh, which has been rendered quite tasteless by boiling with water, acquires the taste and all the peculiarities of roasted BY COLD WATER. 103 flesh, when it is moistened and warmed with a cold aqueous infusion of raw flesh which has been evap- orated till it has acquired a dark brown color.* All sorts of flesh are alike in this respect ; the sapid and odorous constituents are present in the roasted flesh in solution, or in the soluble state. The liquid which The flavor of is obtained by lixiviation of different kinds of flesh the^'ifferem with cold water, after it has been heated to boiling, flesh! and the albumen thus coagulated, possesses, in all cases, the well-known general flavor 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 exam- ple, the concentrated cold aqueous infusion of roe-deer depends on venison or of fowl is added, and the whole warmed matter. * 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 flavor, 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 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 domes- tic arts, long experience and observation have led, in many in- stances, to the most judicious practice. It is the want of a sci- entific basis, however, for the culinary art, that has given rise to many absurd and hurtful methods of preparing food ; as, for example, the very common 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 solu- ble 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. 104 FLAVOR OF MEAT. together, the beef cannot then be distinguished by the taste from the venison or the fowl. A slight addition it is height- of lactic acid (a very little fresh sauerkraut, for ex- ened by lac- tic acid or by ample), or of chloride of potassium, which is an in- chloride of . ' L potassium, variable constituent of all infusions of flesh, heightens the piquancy of the flavor of meat ; as, on the other hand, an alkaline liquid, or the addition of blood, renders the soup or infusion of meat utterly insipid and mawkish. TheHeshof From all the different kinds of flesh we obtain, by old animals ..... . . contains lit- lixiviation with cold water, the whole of the albumen tie albumen, , . .. , , -r,, present in them, in the dissolved state. The quantity of coagulated albumen, which separates from the in- fusion when heated, is very different in different speci- mens, and seems to stand in a certain relation to the age of the animal. The flesh of old animals is pro- portionally poor in albumen, and, on the other hand, but much it is so much the richer in fibrine. 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. Muscular The muscular fibre, in the natural state, is every- where surrounded by a liquid containing dissolved al- bumen. When this is removed, the fibre, in all ani- mals, is of the same quality. The well-washed mus- cular fibre, when boiled with water, becomes hard and its tender- horny, and this the more the longer it is boiled. It ness depends . . on the aibu- is obvious, therefore, that the tenderness of boiled or men of the . . ./.in juice. roasted meat depends on the quantity of the albumen deposited between the fibres, and there coagulating ; for the contraction or hardening of the fibrinous fibres is thereby to a certain extent prevented. This quali- ty, tenderness, however, also depends on the duration of the boiling ; for the albumen also becomes harder by continued boiling, without, however, assuming a tough consistence. BEST METHOD OF BOILING MEAT. 105 The influence of hot water on the quality of the Action of meat which is boiled with it, and of the soup ob- on fSi er tained, hardly requires, after what has been said, any further elucidation. If the flesh intended to be eaten be introduced into Best method . . . of boiling the boiler when the water is in a state of brisk ebul- meat. lition, and if the boiling be kept up for some minutes, then so much cold water added as to reduce the tem- perature of the water to 165 or 158, and the whole kept at this temperature for some hours, all the con- ditions 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 in- wards, and in this state forms a crust or shell, which no longer permits the external water to penetrate into the interior of the mass of flesh. But the tempera- ture 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 juici- ness, 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 retained, under these cir- cumstances, in the flesh. If we reflect that the albumen of the juice of flesh Temperature begins to coagulate at a temperature of 105.5 and that it is completely coagulated at 140 (Berzelius), it might be supposed that it would not be necessary, in the cooking of flesh, to expose it to a higher tem- perature than 140. But at that temperature the coloring matter of the blood is not yet coagulated ; the flesh, indeed, is eatable, but when it contains blood, it acquires, under these circumstances, a bloody ap- underdone pearance, which it only loses, when it has acquired, m throughout the whole mass, a temperature of 150 to 158. 106 HOW TO OBTAIN GOOD SOUP. 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 colors which they present. At all those parts which appear bloody, the temperature has not reached 144. Poultry is I n the boiling or roasting of poultry, the flesh of which sooner done . . . than beef or is white, and contains 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. Use of a By enveloping small pieces of flesh (as is often covering of J lard in roast- done in the case of small birds, such as quails, orto- lans, 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 sur- face, as well as the subjacent parts, is kept in the tender state which is otherwise only found in the inner portions of large masses of flesh. HOW meat is The introduction of the piece of raw flesh into water to obtain 6 already boiling is the best process for the dressing of the meat, but the most unfavorable 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 between 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 GELATINE NOT THE SOURCE OF STRENGTH OF SOUP. 107 the water when coagulated, the surface of the meat more particularly loses its tenderness and shortness (as it is called), becoming tough and hard. The thin- Meat from which soup ner the piece of flesh, the more completely does it ac- has been r . . * made is nei- quire the last-mentioned qualities ; and if in this state ther nutri- tious nor di- it be eaten without the soup, it not only loses much of gestibiewith- , .,....... out the soup. its nutritive properties, but also of its digestibility, inas- much as the juice of the flesh itself, the constituents of which are now found in the soup, is thus prevented from taking part in the digestive process in the stom- ach. The soup, in fact, contains two of the chief con- stituents of the gastric juice. It has long been customary to ascribe to the gelat- Gelatine i* inous matter dissolved during boiling, which gives to ooreof concentrated soup the property of forming a jelly, the ^flavor of h chief properties or peculiarities of the soup ; but there soup ' cannot be a greater mistake. The simplest experi- ments prove that the amount of dissolved 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 mat- Experiment* ter dissolved in the boiling of flesh under the most fa- t h e amount vorable circumstances, finely chopped meat was ex- disfoi*e from 1 ' 000 g ms - of beef > _ C Coagulated Albumen . 29.5 Soluble in cold water 60 $ T C In the solution . . 30.5 .... C Gelatine . . . 6.0 Insoluble in cold water 170 < ., ,, , e .,-. A ( Fibres, Membranes, &c. 154.0 Fat .... 20 Water .... 750 1000 It follows, that boiling water, when allowed to act for five hours on finely chopped flesh, does not dis- solve 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 does not consist of pure gelatine, but contains all the products dissolved out of the muscular fibres by long boiling. SOUP FROM FLESH. 109 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 soluble more of the matters soluble in cold water, and remain- poultry than ing dissolved after the coagulation of the 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 prepar- pid ingradi- ing, in the short space of a few minutes, the strongest exist ready 1 P and most highly flavored soup ; and any one may con- fl e sh e vince himself, by the simplest experiments, 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 in any way products of the operation of boiling. When 1 Ib. of lean beef, free of fat, and separated Best method ... . of preparing from the bones, in the finely chopped state in which it soup, is used for beef sausages or mince- meat, 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 boiling 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. The influence which the brown color of this soup, influence of ^ the brow a 110 PORTABLE SOUP. color of soup or color in general, exercises on the taste, in conse- ment we" quence of the ideas associated with color in the mind form as to / . , x its strength (ideas oi strength, concentration, &c.), may be ren- dered quite evident by the following experiment. The soup, colored brown by means of caramel, is declared by all persons to have a much stronger taste than the same soup when not colored ; and yet the caramel, in point of fact, does not in any way actually heighten the taste. If we allow the flesh to boil for a long time with the . , ., , . water, or if we boil down the soup, it acquires, spon- taneously, when concentrated to a certain point, a brownish color and a delicate flavor of roast meat. If we evaporate it to dry ness in the water-bath, or if pos- sible 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-flavored soup. ^e tablets ? so-called portable soup, prepared in ikSne Pure England an d France, are not to be compared with the extract of flesh just mentioned ; for these are not made from flesh, but consist of gelatine, more or less pure, on- ly distinguished from bone gelatine by its higher price.* Beef yields From 32 Ibs. of lean beef, free from bones and fat weight of ex- (8 Ibs. dry meat and 24 Ibs. water), there is obtained 1 Ib. of true extract of flesh, which, from its necessarily high price, can hardly become an article of commerce ; but if the experience of military surgeons agrees with Extract of that of Parmentier, according to whom "The dried meat recom- . .... mended as a extract of flesh, as an article of provision in the tram for wounded of a body of troops, supplies to severely wounded soldiers. * Note by the Editor. I have seen some specimens of porta- ble soup, which, although consisting chiefly of gelatine, yet had a strong flavor of soup, and probably, therefore, contained a cer- tain proportion of extract of flesh. W. G. SALTING MEAT. Ill soldiers a restorative, or roborant, which, with a little wine, immediately revives their strength, exhausted by great loss of blood, and enables them to bear the trans- port to the nearest hospital," * 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 is Characters of , , . genuine and somewhat more accurately known, it ought to be easy of false ex for every well-informed apothecary to distinguish 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 soup rarely yield to that menstruum more than 4 or 5 per cent. The presence of kreatine and kreatinirie, 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 solu- ble phosphates, furnishes sufficient data for judging of the quality of the true extract of flesh. I consider this extract of flesh as not less valuable Extract of . . meat recom- ior the provisioning of ships and fortresses, in order to mended for preserve the health of the crew or garrison, in those fortresses, a* . . an addition cases where fresh meat and vegetables are wanting, to salt meat. and the people are supported by salt meat. It is universally known, that, in the salting of meat, Salting of 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 ^d of the fluid contained in the raw flesh. I have ascertained that this brine contains the chief The brine of constituents of a concentrated soup or infusion of meat, * See Proust, Annales de Chimie et de Physique. Third Se- ries, Vol. XVIII. p. 177. 112 EFFECTS OF SALTING. ingredients of the ex- tract ; phosphates, lactic acid, kreatine, and kreatinine. Salted meat is deficient in nutritive quality. Causes of this. and that, therefore, in the process of salting, the com- position of the flesh is changed, and this, too, in a much greater degree than occurs in boiling. In boil- ing, the highly nutritious albumen remains in the coag- ulated state in the mass of flesh, but in salting, the al- bumen 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 precipitate of the double phosphate of ammonia and magnesia. It contains also lactic acid, a large quantity of potash, and kreatine, which, although I could not separate that body from the large excess of salt, may be safely concluded to be present, from the presence of kreatinine. The brine, when neutralized by lime, gives, after the salt has been crystallized out, a mother liquid, from which, after some time, when alcohol and chlo- ride of zinc are added to it, the double chloride of zinc and kreatinine, so often mentioned in the former part of this work, is deposited. It is now easy to understand that in the salting of meat, when this is pushed so far as to produce the 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 sub- stances be not supplied from other quarters, it is obvi- ous 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 increased, 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 pre- > EFFECTS OF SALTING. 113 serve 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 conse- quently in that of the products of the digestive process, must be regarded as an inevitable result of the long- continued 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 organ- ism, these parts must lose their normal condition. In my experiments on the salting of meat, I used at Effects pro- first a species of salt which subsequently proved, on meat by salt examination, to contain a considerable proportion of ^ofiSeaof chloride of calcium and chloride of magnesium. I was magnesium, 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 phosphate of lime and phosphate of magnesia. The earthy salts of the sea salt had entered into mutual de- composition with the alkaline phosphates of the juice, producing phosphates of lime and magnesia, of which only very small quantities could be dissolved in the acid brine. In the use of a salt rich in lime and magnesia, there Meat thus may thus be a cause which renders the meat salted with be iess"un^ it less injurious to the system. For it is plain, that w 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 digestion, of the deficient alka- line 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, corn- pared with that of the fodder or food of graminivorous 10* 114 LACTIC ACID IN THE GASTRIC JUICE. animals, which last contains no alkaline phosphates, but phosphates of lime and magnesia along with salts of the alkalies, with other acids. When we compare flesh with other animal food, 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. The soluble If we consider that the juice of flesh, in all ani- of the mS s s mals yet examined, possesses a constant character ; that, essenTiaf to exclusive of those constituents which are derived from MOM. * the blood unavoidably mixed with it, as well as of small quantities of odorous and sapid 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 nu- tritive qualities of any kind of food, the composition of the blood cannot be selected as the proper datum from which to argue, because there are a number of factors which must be brought into the 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 Leh- found in the ... gastric juice mann on the gastric juice of dogs, fed on bones and Lehman n. lean horse-flesh, which fluid he has studied more mi- nutely than had previously been done. He obtained from it a crystallized salt of magnesia, combined with an organic acid, not containing nitrogen. This salt yielded 16.6 p. c. of magnesia, and 21 p. c. of water of crystallization. Now that we know that lactic acid forms a constituent of the chief mass of the body, it is VOLATILE ACIDS OF GASTRIC JUICE. 115 evident that Lehmann's magnesian salt, which agrees with lactate of magnesia in the proportion of base and of water of crystallization, really was lactate of mag- nesia. In that case, the gastric juice contains lactic The digest- acid, and thus the problem of the digestive process in jn^ the stomach would appear, in its chemical aspect, to be completely solved. The experiments of all who have studied the gastric The gastric juice agree in this, that that fluid contains, along with to'the^uice^ an organic acid, free phosphoric acid or an acid phos- phate, 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 alcohol is, in its reac- tion, 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 I have described (ante, p. 109), The soup may perhaps admit of being employed as a valuable scribed pro 3 " remedy for many dyspeptic patients, with a view to in- remedy 8 in creasing the activity of the stomach, and promoting di- ysp gestion. 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 well-made its value to soup during convalescence admits of a simple explana- cents! es ' tion. Finally, when we recollect that lactic and phosphoric origin of the acids, at temperatures in which hydrochloric, acetic, andotter" and butyric acids are volatilized, are almost fixed, we obtained^ * can explain how it happens that in many cases hydro- chloric acid, in others acetic or butyric acid, has been obtained by distilling the gastric juice. Acetates, buty- rates, arid even chloride of sodium, are decomposed by lactic acid, as well as by acid phosphates, in these circum- 116 THE SUBJECT NOT EXHAUSTED. stances, and the occurrence 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. These re- I THINK it right to state, distinctly, that I am far from searches only - > T the com- considering the nature and quality of the substances oc- mencement ..... n . , , , of a more curnng in the juice of flesh as fully ascertained by the complete in- . . , . , ,. vedtigation. investigation contained in the preceding pages. On the contrary, I am of opinion, that it ought only to be re- garded as the commencement 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, demand so much time, that I did not wish to delay the publication of the results hitherto ob- tained till the completion of my researches. Various sub- Of the tissue called muscular, fibrine and albumen distinguish- are the chief constituents in fully developed animals. muscular This tissue is everywhere interwoven with delicate mem- branes, and a number of minute vessels are ramified throughout it, which are filled, partly with colored, part- ly with colorless fluids. No other part of the body ab- sorbs so large a part of the nervous system. As Ber- zelius points out, we must distinguish fibrine, albumen, and cellular tissue, partly organized, partly in the state adapted for their conversion into organized 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 colored and colorless fluids brought to the muscle in the vessels ; SUBSTANCES IN FLESH NOT YET STUDIED. 117 arid the membranes of the distributed nerves, as well as the substance itself of those nerves. When analysis shall have become so perfect as to en- Province of .. . chemical able us to separate these different substances in a ra- analysis, tional manner, she will have fulfilled her 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 fur- ther progress. Kreatinine and kreatine are constituents of the mus- Kreatine and . kreatinine cles, but they are also constituents of urine ; and if any occur both m ,. . 1,1 i i muscle and process in the living body depends upon their pres- in urine. ence, 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 probably very soon shed light on this question. That portion of the juice of flesh which is soluble in Gelatinous cold water, but not in alcohol, possesses all the proper- ^c^offlUh* ties of gelatine, except that of gelatinizing when con- centrated. It is precipitated by tannic acid ; the pre- cipitate softens like plaster in hot water, and cannot be distinguished from the tannate of gelatine by its aspect. A second substance, which I have not yet further in- Another sub- , . . . Al stance in the vestigated, separates, during the evaporation of the juice of flesh, 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 im- agined, caseine. Of the substances soluble in alcohol, the greater part Unknown m- consists of one or probably of more bodies, particularly bodies 1 ^ the i it ! t A i i f juice of flesh. rich in nitrogen ; these are the substances, which, after the phosphoric acid has been removed, give rise, on in- cineration of the residue, to so great a mass of cyanide of potassium. 118 NO UREA IN THE JUICE OF FLESH. New acid in When that part of the juice of flesh which is soluble the juice of . . ... flesh, not yet m alcohol and in ether is mixed with sulphuric acid, to separate the alkali, and the filtered liquid is left at rest for some days, there are deposited long transparent col- orless needles, which have a strong acid reaction and contain no alkali. I first noticed this substance at the close of this investigation, and obtained too small a quantity to enable me to analyze it. Another ni. Lastly, if the acid liquid thus obtained be saturated trogenized .... acid in flesh, with lime, evaporated to dry ness, and the residue washed with alcohol, the addition of ether to the alcohol causes a deposit ; and the liquid separated from this contains kreatinine, combined with an organic acid, rich in nitro- gen, which I have, in like manner, not yet more mi- nutely examined. Urea not I have taken the utmost pains to detect urea or uric juice of flesh, 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, therefore, urea is not a Uric acid constituent of the juice of flesh. In one case only, where I had added chloride of barium to the alcoholic solution of the extract of flesh, crystalline flocculi sep- arated after exposure 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, exactly like uric acid ; and the solution gave with ammonia the same purple color which uric acid would have given in like circumstances. This sub- stance, however, I have not been able again to pro- cure. ADDENDUM. NOTE BY THE EDITOR. FROM the mother liquor which had deposited the kreatine which I prepared, and which contained the soluble matter of nearly 7 Ibs. of fowl, I obtained, by the process indicated at p. 63, by the author, 4 grammes, or about 61 grains, of pure and well-crystal- lized 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 HES- SIAN STANDARD OF WEIGHTS AND MEASURES. 1 lb. English is equal to 0.90719 Ib. 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 Hessian cubic feet. RESEARCHES MOTION OF THE JUICES THE ANIMAL BODY. 11 PREFACE TO THE ENGLISH EDITION. IN (he Editor's Preface to Baron Liebig's " Re- searches on the Chemistry of Food," in which the author gave the results of his investigation into the constituents of the juice of flesh, I men- tioned that Baron Liebig had been led to study the subject of Endosmosis experimentally. The results of this investigation are contained in the following pages ; and the reader will, I trust, be satisfied that the motions of the animal juices depend on something more than mere Endosmosis or Exosmosis, and that the pressure of the atmos- phere, as well as its hygrometric state, by influ- encing the transpiration from the skin and lungs, is essentially concerned in producing these mo- tions. At the same time, the present work is to be regarded, not as exhausting the subject, but, on the contrary, as only pointing out the direction in which inquiry is likely to lead to the most valuable results. 124 PREFACE TO THE ENGLISH EDITION. While it is proved that the mechanical causes of pressure and evaporation, and the chemical composition of the fluids and membranes, have a more direct, constant, and essential influence on the motion of the animal fluids, and consequently on the state of the health, than has been usually supposed, it is evident that very much remains to be done in tracing that influence under the ever varying circumstances of the animal body, and in applying the knowledge thus acquired to the purposes of hygiene and therapeutics. But it is equally obvious, that the above-mentioned mechanical and chemical causes are not alone suf- ficient " to explain the phenomena of animal life, since they are present equally in a dead and in a living body ; so that while every advance in physiology enables us to explain more facts on chemical and mechanical principles, something al- ways remains, which, for the present, is beyond our reach, and which may for ever remain so. However this may be, the facts established in this and in the preceding work of the author have very materially extended the application of the well- known laws of physics and of chemistry to physi- ology, and have also furnished a number of the most beautiful instances of that infinitely wise, but exquisitely simple, adaptation of means to ends which characterizes all the works of the omnipo- tent Creator ; but which is nowhere more admira- PREFACE TO THE ENGLISH EDITION. 125 bly displayed than in the arrangements, imperfect- ly known as they hitherto have been, by which life is maintained. In connection with the author's remarks on the effects of evaporation in plants, and the conse- quences of its suppression, and with his opinions as to the origin of the potato disease, I beg to refer the reader to the Appendix for a very in- genious arid apparently well-founded plan for the protection of the potato-plant against the terrible scourge under which it has lately suffered. The views of Dr. Klotzsch, the author of this plan, as to the nature of the disease, coincide remarka- bly with those of Baron Liebig, as explained in the present work. WILLIAM GREGORY. EDINBURGH, 3d March, 1848. 11 PREFACE. THE present little work contains a series of ex- periments, the object of which is to ascertain the law according to which the mixture of two liquids, separated by a membrane, takes place. The read- er will, I trust, perceive in these researches an effort to attain, experimentally, to a more exact expression of the conditions under which the ap- paratus of the circulation acquires all the proper- ties of an apparatus of absorption. In the course of this investigation, the more intimate study of the phenomena of Endosmosis impressed on me the conviction, that, in the or- ganism of many classes of animals, causes of the motion of the juices were in operation far more powerful than that to which the name of Endos- mosis has been given. The passage of the digested food through the membranes of the intestinal canal, and its entrance into the blood ; the passage of the nutrient fluid outwards from the bloodvessels, and its motion towards the parts where its constituents acquire 128 PREFACE. vital properties, these two fundamental phenom- ena of organic life cannot be explained by a sim- ple law of mixture. The experiments described in the following pages will, perhaps, be found to justify the con- viction, that these organic movements depend on transpiration and atmospheric pressure. The importance of transpiration for the nor- mal vital process has indeed been acknowledged by physicians ever since medicine had an exist- ence ; but the law of the dependence of the state of health on the quality of the atmosphere, on its barometric pressure, and its hygrometric condition, has been hitherto but little investigated. By the researches contained in my examination of the constituents of the juice of flesh, as well as by those described in the present work, the completion of the second part of my Animal Chemistry has been delayed ; but I did not con- sider myself justified in continuing that work until I had examined the questions suggested by and connected with those researches. DR. JUSTUS LIEBIG. GIESSEN, February, 1848. ON THE PHENOMENA ACCOMPANYING THE MIXTURE OF TWO LIQUIDS SEPARATED BY A MEMBRANE. THE constituents of the food, which have assumed a The food be- , , comes soiu- soluble form m the alimentary canal, are thereby en- bie,andintha dowed with the property of yielding to the influence of body is sent every cause, which, in acting on them, tends to change lo their place or the position which they occupy. They are conveyed into the bloodvessels, and thence are dis- tributed to all parts of the body. The movement and distribution of these fluids, and of all the substances dissolved in them, exclusive of the mechanical cause of the contraction of the heart, by which the circulation of the blood is effected, depend, 1. on the permeability of the walls of all vessels to General these fluids ; 2. on the pressure of the atmosphere ; their motion, and 3. on the chemical attraction which the various fluids of the body exert on each other. The motion of all fluids in the body is effected by means of water ; and all parts of the animal system contain, in the nor- mal state, a certain amount of water. Animal membranes, tendons, muscular fibres, carti- Presence of , water in all laginous ligaments, the yellow ligaments of the verte- membranes. 130 RELATION OF THE ANIMAL bral column, the cornea, transparent and opaque, &c., all contain, in the fresh state, more than half their weight of water, which they lose, more or less com- pletely, in dry air. On the presence of this water depend several of their physical properties. The fresh, opaque, milk-white cartilages of the ear become, when dried, translucent, and acquire a reddish-yellow color. Tendons, when fresh, are in a high degree flexible and elastic, and pos- sess a silky lustre, which they lose when dried. By the same loss of water they become, further, hard, horny, and translucent, and when bent, split into whit- ish bundles of fibres. The sclerotic coat is milk-white when fresh, and becomes transparent by desiccation. When these substances, after having lost, by drying, a part of the properties which they possess in the fresh state, are again placed in contact with pure water, they take up, in 24 hours, the whole original amount of water, and recover perfectly those properties which they had lost. The opaque cornea, or sclerotic coat, which had become transparent by desiccation, again be- comes milk-white, while the transparent cornea, which had been rendered opaque by drying, now becomes again transparent. The tendons, which, when dried, had become horny, hard, and translucent, now again become flexible and elastic, and recover their silky lus- tre. The fibrine and the cartilages of the ear, which desiccation had rendered horny and transparent, again become milk-white and elastic. The tissues The power which the solids of the animal body pos- fluids. r sess of taking up water into their substance, and of being penetrable to water, extends to all fluids allied to water, that is, miscible with it. In the dried state, the animal solids take up fluids of the most diverse na- tures, such as fatty and volatile oils, ether, bisulphuret TISSUES TO WATER. 131 of carbon, &c. This permeability to fluids is possessed by animal tissues in common with all porous bodies; and no doubt can be entertained that this property is determined by the same cause which produces the as- cent of fluids in narrow tubes, or in the pores of a sponge, phenomena which we are accustomed to in- clude under the name of capillary action. One condition, essential to the permeability of porous The moisten- , ,. P a -i / i PT- \-XL- ing of porous bodies for fluids (or their power 01 absorption), is their bodies capability of being moistened, or the attraction which the particles of the fluid and the walls of the pores or tubes have towards each otter. A second condition is the attraction which one particle of the fluid has to an- other. We have no means of estimating the absolute size of the particles or molecules of a fluid, such as water, but they are certainly infinitely smaller than the measurable diameter of a tube or of the pores of a porous body. It is obvious, therefore, that in the inte- rior of a capillary tube or pore, filled with a fluid, only a certain number of the fluid molecules are in contact with the walls of the tube, and attracted by them ; while in the middle of the tube, and thence towards its pa- rietes, fluid molecules must exist which only retain their place in virtue of the attraction which the mole- cules attracted by the parietes exert on those not so at- tracted, that is, by the cohesive attraction of the fluid. Liquids flow out of capillary tubes, which are filled with them, only when some other force or cause acts, because capillary attraction cannot produce motion be- yond the limits of the solid body which determines the capillary action. The penetration of a fluid into the pores of a porous depends on . , . . . . capillary at- body is the result of capillary attraction ; its expulsion traction. can be effected by a mechanical pressure, and may be accelerated by increasing this pressure, and by all such AWIMAL TISSUES ARE POROUS. diminish the mutual attraction of tj fluid or the attraction of the walls of the } es for these molecules. The condition most favorabL o the JWMge of a fluid through the pores of a por 3 sub- stance under pressure is when one fluid molec * can be displaced so as to glide away over another. The slightest pressure suffices to expel the ( ^lace- able particles of water from a sponge ; a high< oress- ure is required to express the same fluid from mlous paper ; and a pressure much higher still is necc ary in order to cause water to flow out of moist woe We may form some idea of the force with whicl -orous organic substances, such as dry wood, absorb id re- tain water, if we remember, that, by inserting \v ges of dry wood in proper cuts, and subsequently me ening them, rocks may be split and fractured. When we compare with the properties just amer- ated, which belong to all porous bodies, those -oper- ties which are observed in animal substances u er the same circumstances, it appears plainly that th 3 ani- mal substances have pores in certain direct s, al- though these openings are so minute that they ;.e not, in the case of most tissues, perceptible even h the aid of the hest microscopes. It has been mentioned that tendons, ligamen carti- in, in the fresh state, a certain mount of water, which, apwrfmg to all experiments r..de on is inTanabie ; and that several of the prop- of | nev- wrapped in bulous pressure, a >ertain i an flexi- vel- OF LIQUIDS THROUGH MEMBRANES. 133 under pi ure, is only found in porous substano is obvioi that by pressure, that, is, by diminution of the size the pores, only that portion of water can be prese out which is not retained by chemical at- traction, t is in the highest degree worthy of notice, that thi.* ater, not chemically combined, seems to have the rreatest share in the properties which animal >stances possess in the fresh state, for the pressed ndons and yellow ligaments become trans- parent ; o former lose their flexibility, the latter their elasticit^ and if laid in water, they recover these prop- erties pe 'Ctly. In the pores of a porous substance, the fluid me ules are retained by two kinds of attraction, namely. 7 the affinity which is exerted between the walls ot ie pores and the molecules of the fluid, and by the lesion which acts between the molecules of the fluk self. It would appear as if the molecules of thus brought into different states, and this seems to be the cause of the differences observed in the properties of these animal substances when they contain different pro- portions of water. If the wide opening of the tube, Fig. 1, be tied over with a portion of bladder, and water poured into the wide part of the tube so far as the mark a, we shall find that, when mercury is poured into the upright narrow part of the tube to a certain height, the whole external surface of the bladder becomes covered with minute drops, which, if the column of mercury be made a few lines higher, unite so as to form large drops. These continue to flow out unin- terruptedly, if mercury be added so as to / keep the column at the same height, till 12 not chemical- ly combined OM the great- est share in the proper- ties of the water w Fig. 1 Pressure re- quired to force water and other pass through 134 PASSAGE OF LIQUIDS at last the wide part of the tube is emptied of water and filled with mercury. Solution of salt, fat oil, alcohol, &c., behave ex- actly as water does ; under a certain pressure these fluids pass through an animal membrane, just as water does through a paper fitter. The pressure required to cause these liquids to flow through the pores of animal textures depends on the thickness of the membrane, as well as on the chemical nature of the different liquids. The pressure Through ox-bladder, y^h f a ^ me (yiu 1 ^ f an different" inch) thick, water flows under a pressure of 12 inches of mercury ; a saturated solution of sea salt requires from 18 to 20 inches ; and oil (marrow oil) only flows out under a pressure of 34 inches of mercury. When the membrane used is the peritoneum of the ox, ^th of a line (^yth f an inch) in thickness, wa- ter is forced through it by 8 to 10 inches, brine by 12 to 16 inches, oil by 22 to 24 inches, and alcohol by 36 to 40 inches of mercury. The same membrane from the calf, y^th of a line (y^g-2-d of an inch) in thickness, allows water to pass through under the pressure of a column of water 4 inches high ; brine passes under a pressure of 8 to 10 inches of brine, and oil under a pressure of 3 inches of mercury. In making experiments of this nature, we observe, that, after they have continued for some time, the press- ure required to force the liquid through the membrane does not continue equal. If, during the first 6 hours, a pressure of 12 inches of mercury were necessary, we often find that, after 24 or 36 hours, 8 or even 6 inches will suffice to produce the same effect, obvious- ly because, by long-continued contact with water, the membrane undergoes an alteration, in consequence pf which the pores are widened. THROUGH MEMBRANES. 135 From these experiments it appears that the power of a liquid to filter through an animal membrane bears no relation to the mobility of its particles ; for under a pressure which causes water, brine, or oil to pass through, the far more mobile alcohol does not pass. The capacity of the animal membrane for being Theabsorb- i n i i i enl power of moistened by, and its power of absorbing, the liquid, the mem- brane has a have a certain share in producing the result of its filtra- share in the effect. tion through the membrane. The following table will show this fact : 100 parts, by weight, of dry ox-bladder, take up, in 24 hours, of pure water '. . 268 volumes. Absorption of different " saturated solution of sea salt (brine) . liquids. " alcohol of 84 per cent 38 " " oil of marrow ..... 17 u 100 parts, by weight, of ox-bladder, take up, in 48 hours, of pure water 310 parts by weight. " a mixture of water and f brine . 219 " " h " h brine . 235 " " " | " I " . 288 " " alcohol water . 60 " " " \ " | " 181 " mose properties which they exhibit when saturated with water. A dried bladder continues hard and brittle in alcohol and oil ; its flexibility is in no de- gree increased by absorbing these liquids. When ten- dons, ligaments (Chevreul), the yellow ligaments of the spine or bladder, saturated with oil, are placed in water, the oil is completely expelled, and they take up as much water as if they had not previously been in contact with oil. in C moLrco e n- II has been mentioned, that 100 parts of animal ' miou> membrane (dry ox-bladder) absorb, in 24 hours, 268, in 48 hours, 310 volumes of water, and only 133 of saturated solution of salt. It follows, of course, that when the bladder, saturated with water by 48 hours' contact, and well dried in bibulous paper, without press- ure, to remove superfluous water, is strewed with salt, there is formed, at all points where salt comes in con- tact with the water, filling the open pores, a saturated solution of salt, the salt contained in which diffuses itself equally in the water of the bladder. Of the 310 * In regard to this property, membranes differ in no respect from other animal textures, as was long ago proved by Chevreul. This distinguished philosopher found that the following substan- ces absorbed, in 24 hours, of water, brine, and oil, Cubic 100 100 100 100 100 100 Ce cartilage of the ear . ntimetres C. C. C. C. Water. Brine. Oil. 231 125 178 114 8.6 148 30 7.2 461 370 9.1 319 3.2 301 of water and 148 of alcohol of 69 per cent. (Liebig.) 184 parts by weight, or 154 by volume, ot brine. yellow ligaments of spine cartilaginous ligaments dry fibrine absorbed ON MEMBRANES SATURATED WITH WATER. 137 volumes of water which become thus saturated with salt, only 133 volumes are retained in the bladder ; and in consequence of this diminution of the absorbent power of the bladder for the brine, 177 volumes of liquid are expelled, and run off in drops from the sur- face of the bladder. Membranes, fibrine, or a mass of flesh, behave exact- ly in a similar manner, when in contact with alcohol. If placed in alcohol in the fresh state, that is, when they are thoroughly charged with water, there are formed, at all points where water and alcohol meet, mixtures of the two, and as the animal texture absorbs much less of an alcoholic mixture than of pure water, more water is of course expelled than alcohol taken up. 9.17 grammes of bladder, fresh, that is, saturated Amount of with water (in which are contained 6.95 grammes of p e a iied from water, and 2.22 of dry substance), when placed in 40 akohoi. by cubic centimetres of alcohol, weigh, at the end of 24 hours, 4.73 grammes, and have, consequently, lost 4.44 grammes. In the 4.73 grammes which remain are 2.22 grammes of dry bladder, and, of course, 2.51 grammes of liquid. If we assume that this liquid has the same composition as the surrounding mixture (which is found to contain 84 parts of alcohol to 16 of water), it will consist of 2.11 grammes of alcohol and 0.40 of water; and, consequently, of the 6.95 grammes of water originally present, 6.45 grammes have been ex- pelled, and replaced by 2. 11 grammes of alcohol. For 1 volume of alcohol, therefore, retained by the bladder, rather more than 3 volumes of water have been ex- pelled from it. Since, in this case, so much more water is expelled Moisl mem . than is taken up of alcohol, the first result is a shrink- JjJ?J ing of the animal substance.* * Fibrine and other animal matters exhibit results quite simi- 12* 138 CAUSE OF THE SHRIVELLING OF Pried salt If the bladder could take up or absorb equal volumes cohoi. of brine and water, or of alcohol and water, then, when the fresh bladder was strewed with salt, or laid in alco- hol, the volume of the absorbed liquid would be unal- tered, and an equal volume of saline solution, or of di- luted "alcohol, would be retained by the animal tissue. But since the absorbent power of the tissue for water is diminished by the addition of salt or of alcohol, it fol- lows plainly, that a certain quantity of water must be expelled as soon as its character is changed by the ad- dition of one of these substances. The cause of The relation of bladder, fibrine, and other animal less affinity substances, when saturated with water, to alcohol and for alcohol 10 brine, proves that the shrinking (diminution of volume) fc * of these tissues does not depend on a simple abstraction of water in virtue of the affinity of alcohol and of salt for that liquid ; for it is quite certain that the attraction of alcohol to water, and that of water to alcohol, are respectively equal. The attraction of the water within the tissue for the alcohol without is just as strong as the power of the alcohol without to combine with the water within. Less alcohol is taken up, and more wa- ter given out, because the animal tissue has less attrac- tion for the mixture of alcohol and water than for pure water alone. The alcohol without becomes diluted, the water within becomes mixed with a certain proportion of alcohol, and this exchange is only arrested when the lar to those obtained with bladder. 26.02 grammes of fibrine saturated with water (containing 6.48 grammes of dry fibrine and 19.54 of water) were reduced, in 45 grammes of absolute alcohol, to 16.12 grammes, losing, therefore, 9.90 grammes. Admitting the absorbed liquid to have the composition of the unabsorbed residue (70 per cent, of alcohol), it appears, that for 1 volume of alcohol absorbed by fibrine, rather more than 2 volumes of wa- ter are separated. MEMBRANES WHEN STREWED WITH SALT. 139 attraction of the water for the animal tissue, and its at- traction for alcohol, come to counterpoise each other. If we regard a piece of skin or bladder or fibrine as formed of a system of capillary tubes, the pores or mi- nute tubes are, in -the fresh state, filled with a watery liquid, which is prevented from flowing out by capillary attraction. But the liquid contained in these capillary tubes flows out of them as soon as its composition is altered by the addition of salt, alcohol, or other bodies. If we lay together, one over the other, two portions Expert- of bladder, saturated with solution of salt of sp. g. m 1.204, and over the upper one another piece of bladder of equal size, saturated with water, and if we allow them to remain thus, without pressure, we find, after some minutes, when the two pieces saturated with so- lution of salt are separated, that drops of saline solution appear between them, of which no trace could pre- viously be perceived. If the piece of bladder saturated with water contained 5 volumes of water, and the next piece 3 volumes of saline solution, there must be pro- duced, by the mixture of both, 8 volumes of diluted saline solution, of which each piece of bladder must contain one half, or 4 volumes, if the absorbent power of the portion saturated with the original saline solution were increased by the addition of water in the same ratio as the absorbent power of the portion saturated with water was diminished by the addition of salt. The saline liquid would have given up 1^- volumes of saline solution to the other, and would have received from it 21 volumes of water. In this case, the mixture in the two upper pieces of bladder would occupy the same space which its constituents, water and saline solution, occupied in each singly. But the efflux of the liquid towards the third or lowest piece of bladder, saturated 140 ANIMAL TISSUES ARE Animal tis- with saline solution, proves that the two upper pieces retain a smaller volume of the mixture newly formed in their pores than the one piece absorbed of water alone, and the other of saline solution alone. The power of retaining water is diminished by the addition of salt to the bladder saturated with water ; liquid is expelled ; but by the addition of this water to the blad- der moistened with saline solution, the absorbent power of this piece of bladder is increased, not in the same ratio according to which the proportion of salt is di- minished, but in a less ratio. The experiments above described show that the at- traction of the porous substances for the water which they have absorbed does not prevent the mixture of this water with other liquids. The permeability of animal tissues to liquids of every kind, and the miscibility of the absorbed liquids with others which are brought in contact with the tissues, may be demonstrated by the simplest experiments. If we moisten one side of a thin membrane with fer- rocyanide of potassium, and the opposite side with chloride of iron in solution, we perceive in the sub- stance of the membrane a spot of Prussian blue imme- diately deposited. (Job. Miiller.) which act on All fluids which, when brought together, suffer a each other in i ., ., . i -i the substance change in their nature or in their properties, exhibit, when only separated by an animal membrane, exactly analogous results; they mix in the pores of the mem- brane, and the decomposition commences in its sub- stance. If we tie up one end of a cylindrical glass tube with bladder, and fill it to the height of 3 or 4 inches with water or strong brine, neither the water nor the brine flows out through the pores of Jhe bladder under this slight pressure. every k?nd, PERMEABLE TO ALL LIQUIDS. 141 But if we leave the tube containing brine exposed to Deposit of evaporation in the air, the side of the bladder exposed outside of , i T . , , , , . , bladder from to the air is soon covered with crystals of salt, which brine on the gradually increase, so as to form a thick crust. It is m obvious that the pores of the bladder become filled with brine ; that, on the side exposed to the air, the water evaporates; its place is supplied by fresh brine, and the dissolved salt is deposited, at the external minute openings of the pores, in the form of crystals. If the tube be filled originally with dilute saline solution, the crust of salt is not formed on the outer surface of the bladder until the solution in the tube has reached, by evaporation, the maximum of saturation. Before this takes place, we can perceive in the tube, if we set the liquid in motion, two strata, a heavier and a lighter, the latter swimming on the former. When these strata can no longer be observed, the liquid is in every part satu- rated with salt, and now, by further evaporation, crys- tals are deposited on the outer surface of the bladder. This last circumstance proves that the amount of salt in the liquid is uniformly distributed from below up- wards, from the specifically heavier to the specifically lighter part. If we immerse the tube closed with bladder, and The solutions filled with saline solution, in pure water, the latter ac- through wa- quires the property of precipitating nitrate of silver, even when the contact has lasted only the fraction of a second. The brine filling the open pores of the mem- brane mixes with the pure water, and the latter acquires a certain quantity of salt. In like manner, the pure water acquires a saline im- pregnation, when it is placed in the tube instead of brine, and the outer surface of the bladder is placed in contact with solution of salt. When the tube, closed with bladder, and filled with 142 ENDOSMOSIS AND EXOSMOSIS. brine, is left for a long time with the closed end im- mersed in pure water, the amount of salt in the latter increases, while that of the brine diminishes, till at last the two liquids, separated by the bladder, contain the same relative proportions of salt and water. The same is If the liquid in the tube contain, dissolved, other sub- true of milk and serum, stances, which give to it properties different from those of pure water, and if these solutions be miscible with water, the mixture of them with the water takes place exactly as in the case of brine. This is true of saline solutions of every kind ; of bile, milk, urine, serum of blood, syrup, solution of gum, &c., on the one side, and pure water, on the other. The concentrated liquid loses, the water or diluted liquid gains, in regard to saline impregnation. If we fill the tube with water, and place it in a vessel with alcohol, the water becomes charged with alcohol, while the alcohol becomes diluted with water. Change of There is observed, in these circumstances, that is, dissimilar when two dissimilar liquids, separated by a membrane, ti?rough P biad- mix together, a phenomenon of a peculiar kind ; name- ly, in most cases, a change of volume in both liquids, while the mixture goes on. The one liquid increases in bulk, and rises ; the other diminishes in the same degree, and consequently sinks below its original level. Endosmosis This phenomenon of mixture through a membrane, Ii 9 . " accompanied with change of volume, has been distin- guished by Dutrochet, under the name of Endosmosis and Exosmosis ; endosmose is the name given when the volume increases, exosmose, when it diminishes. Very generally, however, we attach to these terms the idea of the unknown cause or group of causes which, in the given case, produce the change of volume ; in the same sense as that in which the term capillary action includes the causes which determine the ascent of liq- uids in narrow tubes. INFLUENCE OF DENSITY. 143 In all cases, the increase in volume of the one liquid is exactly equal to the decrease in volume of the other, after making allowance for the contraction which the liquids undergo by simple mixture (as in the case -of alcohol and water, oil of vitriol and water, &c.), as well as by evaporation. The unequal concentration or the unequal density of the two liquids has a decided influ- ence on the rapidity with which the change of volume takes place ; but this cannot be viewed as the cause of that phenomenon. In most cases, the denser liquid in- creases in volume ; in others, the reverse occurs. When, for example, the tube contains brine, and the outer vessel pure water, the brine, that is, the denser liquid, increases in volume ; but when the tube contains water, and the outer vessel alcohol, the water, that is, the denser liquid, diminishes in volume. With regard to the mixture of the liquids, the blad- der takes a distinct share in the process, inasmuch as it has pores, through which the two liquids are brought in contact. With reference to the porosity of the bladder, the rapidity of the mixture of the two liquids is dtrectly proportional to the number of particles which, in a given time, come into contact ; it de- pends also on the surface (the size of the membrane), and on the specific gravity of the liquids. The influence of the extent of sur- face on the time required for mixture requires no particular elucidation ; that of the unequal specific gravity is ren- dered evident by the following exper- iments. If the bent tube a I (Fig. 2), one end of which is tied over with blad- Change of volume does not depend alone on the different den- sities of the liquids. Fig. 2. Influence of the unequal density of th liquids when the lighter liquid is above the membrane. 144 CONDITION OF THE MIXTURE, der, and the other open, be filled with brine colored blue,* and if pure water be placed in the tube c, there is soon perceived under the bladder a colorless or nearly colorless stratum of liquid, which continues for hours to float in the same place. If the bent tube a b be filled with colorless brine, while c is filled with pure water colored blue, there is found, after a time, above the bladder, a colorless or nearly colorless stra- tum of liquid. It appears from this, that an exchange of both liquids goes on through the substance of the bladder ; in the first experiment colorless water passes from the tube c to the colored brine in the tube a b ; in the second, colorless brine passes from the tube a b to the colored water in the tube c. It is obvious, that the brine in the tube a 5, which is in contact with the bladder, becomes diluted by the addition of water from the tube c ; but this diluted brine is specifically lighter than the original brine which is below it, and remains therefore floating at its surface. Onthe other hand, the water in the tube c, when mixed with brine from the tube a 5, becomes heavier than the pure water, and rests therefore on the upper surface of the bladder, or that which is turned towards the water. Hence it follows, that from the moment when these two strata have been formed above and below the * For this purpose it is best to take a solution of indigo in sul- phuric acid, diluted, and, after adding subacetate of lead as long as sulphoindigotate and sulphate of lead are precipitated, to sepa- rate the precipitate by filtration and dry up the filtered liquid in the water-bath. A mere trace of the blue residue suffices to give blueness to large masses of liquid. THROUGH MEMBRANES, OF TWO LIQUIDS. 145 bladder, neither concentrated brine nor pure water comes any longer in contact with the bladder. From the bladder downwards in the tube a I are strata of liquid, containing successively more salt; from the bladder upwards in the tube c are strata containing successively more water. In the beginning of this experiment we observe that the volume of the water and of the brine changes in both tubes ; the liquid in the limb b rises from 1 to 2 lines; but as soon as the strata above mentioned have been distinctly formed above and below the blad- der, hardly any further rise is perceptible, although the mixture of the liquid proceeds, and the water in c becomes constantly more charged with salt, while the brine in a b loses salt. If we reverse the positions of the two liquids in the apparatus, Fig. 2, or, what is simpler, if we close with bladder a tube 1 centimetre ( T Vhs of an inch) wide, fill it with brine, and immerse the end closed with the bladder in a wider vessel filled with pure wa- ter, giving to the tube an inclination of about 45, we may observe (most distinctly when both liquids contain some fine particles of indigo suspended) in both liquids a continual motion. We see in the tube (Fig. 3) a cur- rent of liquid rising from the blad- der in the direction of the arrow, and flowing down again on the op- posite side. A similar circulation is observable in the vessel of water. If the tube 0, with brine, is about 2 centimetres (fths of an inch) wide, and if we support it vertically in the vessel b of water, the motion proceds from the middle, and in both the tube and the vessel we per- 13 Fig. 3. 146 PHENOMENA OF THE MIXTURE ceive currents in opposite directions. (Fig. 4.) These currents hardly require ex- planation. To the brine in the tube a, pure water passes through the blad- der ; there is formed above the blad- der a mixture containing less salt, and therefore specifically lighter than the brine ; this mixture rises, and the (Jens- er brine descends to occupy its place. On the other hand, the pure water receives through the bladder salt, and becomes thereby specifically heavier ; while it sinks to the bottom of the vessel, its place is supplied by water containing less or no salt, and therefore specifically lighter, which again comes in contact with the bladder. As long as the motions just described are perceptible, we observe a constant increase in the volume of the brine in the tube a (Fig. 4), or a diminution in the volume of the pure water in the vessel b. When the motions cease, the rise of liquid in the tube is arrested, and when this takes place, the two liquids are found to possess almost ex- actly the same specific gravity. When the two strata of liquid on either side of the bladder are little different in composition (as soon comes to pass in the experiment (Fig. 2) where the saline contents of the liquid which fills the pores of the bladder can hardly vary from that of the next stratum), the mixture of the liquids takes place, but without further change of volume. But when an ex- change of the mixtures on the opposite sides of the bladder can occur in consequence of their different specific gravity, and when a continued difference be- tween the strata on opposite sides of the bladder is thus determined, then, so long as (in the case of brine OF TWO LIQUIDS THROUGH A MEMBRANE. 147 and water, for example) one side of the bladder is in contact with a concentrated, the other with a more diluted solution, the change of volume in the two liq- uids continues. As appears from these experiments, the change of volume depends on a difference in the character -of the two liquids which are connected through the bladder ; and the time during which change of volume occurs is in direct proportion to the time during which this difference in character subsists. The greater the differ- ence in character and composition between the liquids, and the more rapidly this difference is renewed by the exchange between the strata in contact with the opposite sides of the bladder, the more rapidly does the one liquid increase, and the other diminish, in volume. The following apparatus is very convenient for meas- The change , , . , 111- f* m volume unng the change in volume caused by the mixture of made by a i. . i .11 membrane two liquids separated by a membrane. Fig. 5. The tubes a and b (Fig. 5) are of equal width, and are best taken from the same tube ; a is closed with bladder, and filled up to a certain point with the liquid whose increase in volume is to be determined. It is then fitted by means of a good cork into the wider tube c, which contains distilled water, care be- ing taken to exclude all air-bubbles. At d lies a small lead drop,, which acts as a valve in shutting the opening of jjj the capillary tube connecting c with I. Pure water is now poured into 5, and in order to keep in equilibrium the lead drop at d, rather more water is added than exactly suffices to bring the liquids to the same level in both tubes. 148 PHENOMENA OF THE MIXTURE The liquid in a increases in volume, and the height to which it rises may be read off by means of any division into equal parts by measure ; the level of the liquid in b sinks in an equal ratio. If we keep the liquid in Z>, by the addition of fresh water, at the origi- nal level, and if we ascertain the weight of the added water, by pouring it out of a dropping bottle, and de- termining the loss of weight in the dropping bottle, we learn at the same time the weight and the volume of the water which has risen from c into a. This ap- paratus admits, of course, of a number of variations and improvements. I have employed it to determine the relation between brine and water, under the cir- cumstances just described. It appeared, among other things, that when the tube a is filled with saturated solution of sea salt, the volume of the liquid increased by nearly one half; that is, 200 volumes of such a solution increased to 300. These deter- minations are, however, not the object of the present investigation, and therefore I pass them over entirely. The following arrangement (Fig. 6) will probably be found preferable to the one just described, in many cases. Its con- struction depends on the observation, that, for the phenomenon itself, and for the re- sult of the experiment, it is entirely a mat- ter of indifference whether the tube be closed with a single, double, or treble lay- er of bladder.* For experiments on very thin membranes which are permeable to liquids under a very low pressure, the apparatus (Fig. 5) is obviously better * In these experiments membranes of all kinds may be used. With the thinner membranes, such as the bladder of the calf Fig. 6. OF TWO LIQUIDS THROUGH A MEMBRANE. 149 adapted. For the explanation of the phenomenon, we have to distinguish, 1. The mixture of different liquids, 2. The change in their volume. As to the mixture of two liquids of dissimilar nature Cause of the motion of and characters, this always depends on a chemical at- dissimilar . liquids. traction. In a mixture of alcohol and water, or of brine and water, there is in every part the same proportion of particles of alcohol and water, or of salt and water. If, in the former, the lighter particles of alcohol lying at the bottom of the vessel were not retained in the place and arrangement which they occupy by the surrounding particles of water, they would undoubtedly rise towards the surface. In like manner, the particles of salt in the brine are sustained and prevented from sinking by the lighter particles of water which surround them. Without an attraction, which all the particles of al- cohol or of salt must have towards all the particles of water, or all the particles of water must have for all those of salt and alcohol, a uniform mixture cannot even be conceived. If but one particle of alcohol were less powerfully attracted than the surrounding particles, it would rise to the surface ; and, in like man- ner, the particles of salt would, in consequence of their greater specific gravity, gradually occupy the bottom of the vessel, were it not that a cause prevents them from rising or falling ; and this cause can be nothing but an attractive force, which retains them in the place where they happen to be. The cause which effects a change in the place or Chemical at- , ./.,,. i traction is m the properties of the ultimate particles or atoms the cause of the motion of and the pig, the experiments are more rapidly completed than with the thicker, such as the gall-bladder and urinary bladder of the ox. The peritoneum of the ox and calf is preferable to all others. The tube c is tied with bladder under water. 13* 150 CHEMICAL AFFINITY of dissimilar substances, when these particles are in ab- solute contact, or at infinitely small distances from each other, as well as the cause which manifests itself as a resistance to such changes of place or properties, we call chemical attraction ; and in this sense the mix- ture of two dissimilar liquids, the simple moistening of a solid body, the penetration and swelling of it by a liquid, are effects in which chemical affinity or attraction has a decided share ; and although we are accustomed to limit the notion of affinity to such cases as exhibit a change perceptible to our senses, in the properties of the substances employed, as, for example, when sul- phuric acid and lime, or sulphur and mercury, combine together, this limitation arises from the imperfect appre- hension of the essence of a natural force. Affinity is Everywhere, when two dissimilar bodies come in act[ve W be ere contact, chemical affinity is manifested. It is a univer- IrTcontact! 68 sa l property of matter, and by no means belongs to a peculiar class of atoms, or to a peculiar arrangement of these. But chemical combination is not, in all cases, the result of contact. Combination is only one of the effects of affinity, and occurs when the attraction is stronger than all the obstacles which are opposed to its manifestation. When the forces or causes which oppose chemical combination heat, cohesive attraction, electric attrac- tion, or whatever they may be called preponderate, then chemical combination does not take place ; and effects of another kind are manifested. Melted silver in a crucible, surrounded with red-hot coals, in a place, therefore, where we should hardly anticipate the presence of free oxygen, absorbs as much as ten or twelve times its volume of that gas. Metallic platinum exhibits the same property in a far higher degree ; for from the atmospheric air, a gas- IS UNIVERSALLY DIFFUSED. 151 eons mixture in which oxygen forms only the fifth part, that metal (in the form of a black powder) condenses on its surface, at the ordinary temperature, an enor- mous quantity of oxygen gas (without any nitrogen), and acquires thereby properties which it does not otherwise possess.* And when oxide of chromium, fragments of porcelain, or asbestos, at high tempera- tures, effect the combination of two gases, oxygen and hydrogen, or oxygen and sulphurous acid, which gases do not combine at the same temperature, unless when in contact with these solid bodies, it is to the chemical attraction or affinity of these solid bodies that we must ascribe this effect. The solution of a salt in water is an effect of affin- ity, and yet no one property, either of the salt or of the solvent, is thereby altered, except only the cohe- sion of the saline particles. Sea salt, the crystals of which are usually anhydrous, Crystaiiiza- . _ n lion of sea takes up, at very low temperatures, 38 per cent, of salt, water of crystallization ; not because any new cause acts which increases its affinity for the particles of water (for cold is no cause, but the absence of a cause), but because the higher temperature acted as an obsta- cle, opposing their chemical combination. The force of affinity is all the time present and undiminished. When we add alcohol to the solution of a salt in Precipitation of salt from water, we observe that now the salt separates from the its solution liquid in the form of crystals, doubtless only because, by the addition of another chemical force, the amount of attraction between the particles of the salt and those of the water has been altered. The aqueous particles, which were combined with * According to Doebereiner, platinum black condenses 252 times its volume of oxygen. Its effect in oxidizing alcohol, pyroxilic spirit, &c., is familiar to every chemist. W. G. 152 ACTION OF LIQUIDS AND SOLIDS the saline particles, manifest an attraction for the par- ticles of alcohol ; and as the latter have no affinity, or only a very feeble affinity, for those of the salt, the attraction of the saline particles for each other is strengthened. This attraction was present in equal force before the addition of the alcohol, but the resist- ance which opposed their union (the chemical attrac- tion for them of the aqueous particles) was more pow- erful. The alcohol was not the cause of the separa- tion. The cause of the separation of the salt from the liquid, its crystallization, is at all times the force of cohesion ; and by the alcohol the cause which opposed its manifestation was removed. Precipitation The affinity of potash for sulphuric acid is known, of potash by and sulphate of potash readily dissolves in water. If we add to a saturated solution of that salt an equal vol- ume of aqua potassse of sp. g. 1.4, there is immediate- ly formed a crystalline precipitate of sulphate of pot- ash, and the sulphuric acid is separated in this form from the water. In these cases the chemical effect (the separation) depends on the presence of a certain quantity of the liquid which is added (such as aqua potassse, alcohol, &c.) ; but in many other cases there is required only a slight alteration in the quality of the solvent to effect separations of this kind. Precipitation When hydrochloric acid is added to a solution of fer- rocyanfc f acid rocyanide of potassium, hydroferrocyanic acid is set by ether. ^^ an( j remams dissolved in the liquid. If now the vapor of boiling ether be passed through the mixture, there occurs, after a few moments, a complete separa- tion. The whole of the hydroferrocyanic acid is de- posited from the liquid in the form of white or bluish- white crystalline scales, which generally appear in such quantity as to render the whole mass semi-solid. ON DISSOLVED MATTERS. 153 In proportion as the vapor of ether is dissolved by the water, the latter fluid loses entirely its solvent power (its affinity) for the hydroferrocyanic acid. The coagu- lation of albumen by ether depends on a similar cause. The capacity of solids to become moistened by liquids, and, in short, all phenomena connected with chemical affinity, are affected, altered, increased, or destroyed by causes quite analogous. After heavy rains, the water of many rivers becomes turbid and opaque from the presence of a fine clay. These suspended particles of clay are so fine as to pass through the finest filters ; and their adhesion to the water is so great, that such water does not clear after standing for weeks. The water of the Yellow River, in China, possesses, during the greater part of the year, this character ; and from the French missionaries we know that alum is universally employed in Pekin to clear it. In fact, if a crystal of alum be held in such a water only for a few seconds, we observe the sedi- ment separating in large, thick, flocculent masses, the water becomes transparent, and hardly a trace of dis- solved alum is to be detected by the most delicate re- agents. Chemistry is acquainted with a number of similar means for causing the separation from liquids of suspended precipitates. In these cases we see, that, by an alteration of the quality of the water, produced by what we call mere mixture with a foreign body, its power of combining with others is destroyed or weakened. It is well known that the force with which, in a solu- Action of .. _ . . , . ,. solids on dis- tion, the particles of the liquid and those of the dis- solved mat- solved body attract each other is very unequal in differ- ent cases ; and in this point of view the action of many solid bodies on saline solutions is very remarka- ble, inasmuch as it is thereby demonstrated that the 154 ACTION OF SOLIDS ON DISSOLVED MATTERS ; molecular force, which determines the phenomena of cohesion, and the moistening of solid bodies by .liquids, appears to be identical with chemical affinity, since chemical compounds can be decomposed by means of it. Professor Graham has shown that common char- coal, deprived by acids of all soluble ingredients, com- pletely removes the metallic salts or oxides from solu- tions of salts of lead, tartar emetic, ammoniated oxide of copper, chloride of silver in ammonia, and oxide of zinc in ammonia ; while other solutions, such as that of sea salt, suffer no such change. A bleaching solution of hypochlorite of soda loses entirely its bleaching prop- erties by agitation with charcoal ; and iodine can be removed by the same means from its solution in iodide of potassium. Every one is familiar with the action of finely divided platinum, with that of silver, on the deutoxide of hydrogen ; as well as with that of char- coal on dissolved organic matters, coloring matters, &c. ; and freshly precipitated sulphuret of lead, sulphu- ret of copper, and hydrate of alumina resemble the lat- ter in their action. Many organic substances, such as woody fibre and others, act on dissolved matters, such as salts of alumina or of oxide of tin, just as charcoal does; and we know that the application of mordants in dyeing, and dyeing itself, depend on this very property. The adhesion of the solid coloring matter to the cloth which is died with it is the result of a chemical affinity so feeble, that we hardly venture to give the molecular force that name in this case. From a piece of woollen cloth dyed with indigo, the indigo is completely separat- ed, by mere beating, continued for some time, with a wooden hammer, so that the wool is at last left white. The surface of the solid body exerts, as these facts prove, a very unequal attraction on the molecules which come in contact with it. OF TWO DIFFERENT LIQUIDS. 155 Researches on capillary attraction have shown, that, with one and the same liquid, water, for example, the substance of the solid body has no influence on the height to which the liquid rises on it. On slices of box- wood, clay-slate, or glass, the rise of the liquid above the surface of the water is the same exactly as in the case of a plate of brass. (Hagen.) In the case of other liquids, the particles of which are entirely homo- geneous, the same law may be assumed in theory ; -but with such liquids as contain foreign bodies in solution, a change in the capillary attraction must be produced by the presence of these bodies, because by them the cohesion of the liquid is altered ; and perhaps still more, because the liquid ceases to be homogeneous when the attracting wall has a stronger affinity for the particles of the dissolved body than for those of the solvent. From what has been stated, it appears that the mix- ture of two liquids is the result of a chemical attrac- tion; for how otherwise could chemical compounds, such as the solution of a salt in water, be decomposed, or a chemical attraction be overcome, by its means ? Two liquids of different chemical properties, which Laws of the mixture of are miscible together, and which, therefore, have a two dissimi- lar liquids. chemical attraction for each other, mix readily at all points where they come in contact. By motion, shak- ing, &c., the number of points of contact within a giv- en time is increased, and the formation of a Uniform mixture is thus accelerated. If these liquids be of equal, or still better, of un- equal, specific gravity, they may be, with the aid of some precaution, stratified one above the other. This is, in point of time, the most unfavorable case for the mixture, since proportionally small surfaces come in contact. But wherever they do come in contact, it is, after a very short time, impossible to detect any limit between them. 156 LAWS OF THE MIXTURE In a cylindrical vessel, containing solution of salt, the saline particles at the surface are attracted and sus- tained by aqueous particles, which exist at the sides of the saline particles, and from the surface downwards. From the surface upwards, the attracting aqueous parti- cles are absent. Now it is evident, that, when the surface is brought in contact with pure water, a new attraction is added to those previously existing, which acts in an opposite di- rection, namely, the attraction of the aqueous particles floating on the surface for the saline particles, and vice versa (the attraction of the saline particles to the aqueous particles in contact with them). At the place where pure water and brine are in con- tact, there is thus formed a uniform mixture of the two, which upwards is in contact with pure water, down- wards with brine. Among these three strata, of which the upper con- tains no salt, the lower less water, a new division takes place ; the more strongly saline stratum loses salt, the pure water becomes saline, and in this way salt and water are at last uniformly distributed throughout the liquid. Experiments If we fill the limb of the tube (Fig. 7), Fig 7i formationof as f ar as a, with brine colored blue, and uvoTiq U ukis. f * ne other limb with water, we find, in the course of a few days, the water colored blue, and the proportion of salt in both limbs equal. It has been mentioned at p. 141, that in a tube closed with bladder, filled with diluted solution of salt, and exposed to evaporation, the salt is not de- posited in crystals on the outer surface of the bladder till the whole liquid in the tube has reached, in consequence of evap- OF DIFFERENT LIQUIDS. 157 oration, the maximum of saturation. The water evap- orates from the exterior of the bladder, but no salt is deposited as long as a liquid exists within which salt can still dissolve ; and in this way the heavier saline particles are distributed towards the interior, and up- wards through the whole liquid, or, what amounts to the same, the lighter aqueous particles, which can still dis- solve salt, are distributed downwards towards the exter- nal surface of the bladder. This distribution of salt through water takes place in The distru.u- 3 . lion of salt the same manner as the conversion of bar iron into through wa- * T> ter resembles sreel. Rods of malleable iron, as is well known, are theconver- .... sion of iron kept ignited between strata of charcoal, whereby the to steel by surface of the iron in contact with the charcoal takes up carbon, and becomes a carburet of iron. The stra- tum of iron lying next under this surface, which has the same attraction for carbon, acquires carbon from the superficial stratum immediately in contact with it, and in its turn gives carbon to the stratum below itself. This process, if continued long enough, has no limit till all the strata of particles have acquired an equal pro- portion of carbon, that is, till they are all saturated with it. A piece of red-hot malleable iron, if kept a few moments in contact with pig iron (a carburet of iron), is found to be already converted into steel at the points of contact. The mixture of liquids depends on the same principle ; and we may suppose that their distri- bution is mutual, because their particles may move in all directions, and that consequently saline particles move towards aqueous particles, as well as aqueous towards saline particles, in virtue of their mutual at- traction. From a solution of sulphate of copper in ammonia, placed in a tall glass cylinder, there is gradually sepa- rated, if we pour a stratum of alcohol on the surface, 14 158 LAWS OF THE MIXTURE and if we prevent the formation of a coherent crust which impedes the contact of the liquids, the whole of the ammoniated sulphate of copper, while the deep blue solution becomes colorless, because by the distribution of the alcohol through the solution a mixture is formed, in which the salt is insoluble. Mixture is The rapidity of mixture of two liquids depends on chemical the degree of their chemical affinity ; and the unequal mobility of the particles of one or the other liquid has a favorable or unfavorable influence on the result. by unequal When the one liquid is heavier than the other, and of mobility, and , , . . -, by unequal tough, viscid consistence, a much longer time elapses theiiquids. before the ingredients of the tougher or heavier liquid reach the surface from the bottom of the vessel ; and in this case the greater density and the less mobility of the particles are obstacles to the mixture. On the other hand, if the heavier or more viscid liquid be placed above the lighter, the mixture takes place rapidly ; at the points where both liquids are in contact is produced a mixture, which, being heavier, de- scends, whereby the heavier liquid above is continually brought in contact with new surfaces of liquid. Effect of po- The very same phenomenon is observed in solution. sition on the A _ solution of a A fragment of sugar, when covered with water at the bottom of a narrow cylinder, dissolves very slowly, while, if suspended just below the surface, it rapidly disappears. In the former case there is produced round the sugar a thick, syrupy, viscid solution, which pro- tects the undissolved part of the sugar for a long time from contact with the water; in the latter, there is formed at the surface a solution, which descends in striae, and gradually disappears, while, by the change of place thus induced, new portions of water are constant- ly brought in contact with the undissolved sugar, and are thus enabled to exert their solvent powers. OF TWO DIFFERENT LIQUIDS. 159 If skin and membranes consist of a cohering system of very narrow tubes, it is obvious tbat when two dis- similar but miscible liquids are separated by such a tissue, the pores of the tissue will fill with each of the two liquids. In all situations where the liquids come in contact in the substance of the membrane, a mixture takes place, and this mixture is extended equally tow- ards both sides. If there be brine on one side of the bladder, and water on the other, there must be formed, in the middle, or at some point of the bladder, a diluted brine, which on the side in contact with the water yields salt to that water, while on the opposite side the strong brine mixes with the diluted brine in the bladder. The substance of the bladder has no influence on this mixture, because it can produce no change of place on the part of the saline or aqueous particles, for this is the result of the chemical affinity acting between the particles of salt and those of water. Now, since the rapidity of the mixture of two liquids Rapidity of . stands in a direct proportion to the amount of their sur- faces coming into contact within a given time, and since the liquids, separated by a bladder, can only come in contact through its pores, while the number of points of contact is diminished by the presence of the non- porous parts of the bladder, it follows, that, exclusive of all other effects, the time required for mixture must be lengthened by the interposition of a bladder. In the absence of the bladder, the mixture would take place exactly as when it is present, except in regard to time. When the heavier brine is under the water above the bladder, the two liquids mix more slowly than without the bladder. But since a bladder, inasmuch as a feeble hydrostat- incertaincir- cwmstauees 160 CAUSE OF THE CHANGE OF VOLUME IN the interpo- ical pressure is not propagated through its pores, allows sition of a . . . membrane us to place a heavier liquid above a lighter, and to re- accelerates .... mixture. tain it in that position, this circumstance has the effect of promoting mixture, the ultimate cause of which is, not the" bladder, but the specific gravity of the liquid. The bladder is a means of enabling the specific gravity to influence mixture. The foregoing remarks appear to me sufficiently to elucidate the share taken by the bladder in the mixture of two dissimilar liquids placed on opposite sides of it. change of With respect to the change of volume in the two two liqukis liquids which become mixed through the bladders, we through a must consider that the moistening or the absorbent power of a solid body, as well as the power of a liquid to moisten other bodies, is the result of a chemical ac- tion, is the result Liquids of different properties, or of different chemi- of chemical , , . affinity mod- cal characters, are attracted with unequal degrees of lary attrac- force by solid bodies, and exert towards them unequal degrees of attraction, and if we alter even in a system of capillary tubes, filled to a certain height with a liquid, the chemical nature of that liquid, we change thereby the height at which the liquid stands. In an animal tissue saturated with water, the water is pre- vented from flowing out by the mutual attraction, and by the capillary force, but if the attraction of the or- ganic parietes for water be diminished by the addition of alcohol or of salt to the water, a part of it flows out. To this must be added, that the water absorbed by an animal texture when it enters the capillary tubes exerts, in virtue of its attraction for the tubes, a certain press- ure, by which the vessels are swollen and enlarged. The particles of liquid in these tubes uridergo a counter- pressure from the elastic parietes, by which pressure, when the attraction of the liquid particles for the solids LIQUIDS MIXING THROUGH A MEMBRANE. 161 is diminished by any new cause, the amount of expelled fluid is increased. The organic parietes of the tubes, saturated with water, are affected by alcohol just as a salt is when dis- solved in water. On the addition of alcohol, or of an- other liquid, the water separates from the salt, or from the parietes, or the parietes separate from the water. If the animal tissue possessed as great an attraction for the newly formed mixture as for the water alone, the volume of the liquid would not change. The mix- ture would take place, but no water would flow out. A bladder, saturated with water, when brought in contact with alcohol, shrinks together, a part of the water separates from the animal matter, but there al- ways remains in the bladder a certain amount of water, corresponding to its attraction for the bladder and for the alcohol ; just as the solutions of many salts which have a strong attraction for water (such as metaphos- phate and acid phosphate of soda), and are insoluble in alcohol, are separated by the addition of alcohol into two strata of liquid, the heavier of which is a more concentrated solution of the salt in water, containing a little alcohol, while the other, the lighter, is an aque- ous liquid containing much alcohol. The alcohol and the salt divide between them the water of the solu- tion. When we add, to a mixture of equal parts of acetone Action of and water, a certain quantity of dry fragments of chlo- calcium on ride of calcium, the first fragments which are added LTto X nTand f deliquesce and dissolve entirely in the mixture. But if water< we go on adding the salt, a separation soon occurs, two strata of liquid are formed, of which the upper contains acetone and water, the other is an aqueous solution of the chloride with a little acetone. If we add still more of the chloride, water is abstracted from the acetone of 14* 162 EFFECT OF EVAPORATION ON the upper stratum, and when a proper quantity has been added, the acetone retains no trace of water. If we suppose, that of the two originally formed strata of liquid, one of them, namely, that which sinks and contains chloride of calcium dissolved, is in con- tact with a current of dry air, the water of this solution will evaporate, the solution will thus become stronger, and in consequence of its increased concentration will be able to remove a new portion of water from the mixture of acetone and water above it ; and this will continue till the acetone is entirely deprived of water. If in the place of the chloride of calcium we put a bladder, and, in place of the acetone and water, diluted alcohol, we have the finest example of the unequal at- traction which the animal tissue exerts on the two ingre- dients of the mixed liquid. Effect of It is known, from the experiments of Soemmering, evaporation upon a mix- that spirits of a certain strength inclosed in a bladder, ture of alco- . . hoi and water which is exposed to the air, lose by evaporation only water, and that at last anhydrous, or nearly anhydrous (absolute), alcohol is left in the bladder. When strong spirits of wine are used, the bladder remains dry exter- nally ; when weaker spirits are employed, it becomes moist, and alcohol evaporates with the water. In virtue of the unequal affinity of the bladder for alcohol and for water, a complete separation is here effected. The water of the mixture is absorbed, and evaporates from the outside of the bladder ; the alcohol remains in the bladder. As yet, we are acquainted with no substance which can replace the bladder in this operation ; and indeed the affinity of the gelatinous tissues (membranes, &c.) for water must exceed that of all other animal tissues, since a rise of temperature, of a few degrees only, suffices to enable water to dissolve that tissue per- fectly into a jelly. LIQUIDS CONFINED BY MEMBRANES. 163 Magnus assumes " that the particles of every solu- views of i / i, ji Magnus on tion, for example, of a salt in water, adhere more Endosmosis. strongly to each other than do those of the solvent, for example, of water ; consequently, the solution would be less fluid, and pass with greater difficulty through very narrow openings, than water, if we take for granted that the parietes of the openings act alike towards both. It would follow from this, that, the more concentrated a solution, the less easily would it pass through the same openings." " Let us now try," pursues Magnus, u with the aid of these assumptions (which, as appears from the experi- ment, Fig. 1, are perfectly accurate and demonstrable for many saline solutions, although there are, according to the researches of Poiseuille, a number of excep- tions*), to explain the phenomena of Endosmosis." " Both the brine and the water will penetrate into the pores of the bladder, and brine will pass from the pores to the water, as well as water to the brine, in virtue of their mutual attraction, till a complete equi- librium is established. Further, since the force which attracts the water to the brine is exactly the same as that which attracts the brine to the water, as much wa- ter as brine would pass through the bladder, if both liquids could pass with equal facility through the pores. Since, however, this is not the case, unequal forces are required to urge the two liquids through the pores; or, with equal forces, unequal quantities of the two pass through in equal times. There is, consequently, added more of that which passes most easily, the water to the brine, than of the latter to the water, and the level of both liquids must change, if no other force oppose this change." f * Ann. de Ch. et de Phys., 3d Series, XXI. pp. 84 et seq. \ Poggendorff's Annales, X. p. 164. 164 VIEWS OF MAGNUS According to this theory, brine and water exist in the pores of the bladder in a state of motion, and the chemical affinity which the particles of the brine have for the particles of the pure water, and, conversely, which the particles of water have for those of salt, is considered as the cause of this motion. The unequal velocity, which makes more water flow in a given time to the brine than brine or salt to the pure water is, ac- cording to %Iagnus, .determined by the unequal resist- ance which the substance of the bladder opposes to the passage of the two liquids. Now, however narrow the tubes may be in which molecules are set in motion by an external force, it may always be assumed, that that part of the mole- cules which is immediately in contact with the wall of the tube either is not in motion, or possesses only a small velocity, and the velocity of efflux must be a function of the cohesion, and at all events not depend- ent on the wall of the tube. If now the efflux of the water on one side of the bladder is produced by the attraction of the saline par- ticles for the water, and the efflux of the brine on the other side is produced by the attraction of the aqueous particles for the saline particles, it is impossible to ex- plain how water and brine can move in the same tube with unequal velocity in opposite directions ; the two liquids being supposed to have a mutual attraction, that is, to be miscible. This attraction must act within the tube just as well as without ; and we might therefore suppose, that, when the two liquids have become mixed, the mixture could only move in one direction with a medium velocity. Assuming that a mixture is formed in the open orifi- ces of the pores or tubes, or in any part of them, it is difficult to see why saline particles should not pass ON ENDOS3IOSIS EXAMINED. 165 from one side to the water, or aqueous particles to the saline ones in the bladder, since the mutual attraction must be regarded as equal on both sides. The chem- ical affinity of the two liquids does not explain the efflux. If we suppose, that in certain pores only brine, in others only, pure water, moves, the phenomenon ought not to occur when all the pores are filled with water or with brine, or when the tube is tied with a double, treble, or fourfold bladder. But the properties of blad- der are seen in the finest as well as thickest membranes, and one, two, or three layers make no difference in the ultimate result.* * With respect to the theory, that, when a saline solution is mixed with pure water, if the two liquids are separated by a membrane, particles of salt alone pass through the pores of the bladder to the water, and particles of water alone to the brine, the following experiments may throw some light on the ques- tion. For the sake of greater accuracy, the results were deter- mined by weighing. The apparatus Fig. 3 was used. The tube contained 8.67 grammes of saturated brine, in which were 2.284 grammes of salt and 6.38 of water. After 24 hours it had gained 1.79 grammes in weight, and it now contained only 0.941 grammes of salt. It had, therefore, lost 1.343 grammes of salt, and gained 3.13 of water. According to the above theory, 1 atom of salt and 15 atoms of water must have moved past each other; but this is impossible, since 1 atom of salt requires 18 atoms of water for solution (10 parts of salt to 27 of water). The weight of the pure water in the outer vessel was 19.26 grammes ; consequently, the weight of the brine was to that of the pure water as 1 : 2.22. In another experiment, in which the weight of the brine in the tube was to that of the water out- side, as 1 : 7.98, the tube gained 0.822 grammes in weight ; the liquid in the tube contained at first 0.947 grammes ef salt ; and 24 hours after, 0.148 grammes: hence, 1.621 grammes of water had entered, while 799 grammes of salt had passed out. For 1 atom of salt, which passed from the tube with brine to the vessel with water, there passed from the latter to the former rather more than 13 atoms of water (for 58.6 parts, or 1 atom of salt, 118 parts of water). 166 THE MIXTURE IS INFLUENCED BY THE The nature of the mem- brane has an important in- fluence. Experiments with bladder and caout- chouc. Experiment to prove the attraction of the bladder for the liquid. The kind of influence which the nature of the par- tition, or its attraction for the liquids in contact with it, exerts on the phenomenon, is seen by comparing the action of an animal membrane with that of a thin sheet of caoutchouc. In a tube, closed with bladder, which is filled with alcohol and immersed in pure water, the volume of the alcohol is increased ; more water passes to the alcohol than alcohol to the water. If, without making any other change in the exper- iment, the tube be closed with a thin sheet of caout- chouc, the volume of the alcoliol now diminishes, while that of the water increases. Here, all the circumstances of the mixture of the two liquids have remained the same, except the nature of the partition, which makes the difference in the result. When we fill with brine a tube closed with bladder (Fig. 8), and place it in a vessel of water, so that the bladder and water only commu- nicate by a single drop, the liquid in the tube increases in bulk, and rises in the tube, as if the bladder had been immersed in the water ; but the drop becomes gradually smaller, till, after an hour or two, a complete separation takes place, and the drop tears itself away from the water.* If the cause of the change of volume in this exper- * If we pour into a tube of an inch wide, and closed with bladder, as much mercury as covers the surface of the bladder, then fill it with brine, and place it in pure water, the volume of the liquid in the tube increases exactly as if the mercury were not there. ATTRACTION OF THE MEMBRANE FOR THE LIQUIDS. 167 iment were the unequal resistance which the bladder Unequal at- . . j traction of opposes to the passage 01 the two liquids with equal membrane . . . . for different attraction (equal force) on both sides, the phenomenon liquids, just described would be inexplicable ; for a resistance can no doubt impede, but is not capable of producing, motion. But we see that the water in this experiment is raised to a higher level, and, moreover, the tearing asunder of the drop can only be the effect of a pow- erful attraction, residing in the substance of the blad- der. If the moistening of solid bodies by liquids be the effect of a chemical attraction, the force of which is different in dissimilar liquids, it follows, that when a porous body is saturated with a liquid, and brought in contact with a second liquid, which has a stronger at- traction for its substance than the first has, then the first liquid must be displaced from the pores by the second, even in the absence of hydrostatic pressure, and this whether the two liquids be miscible or not. We may suppose that the attraction of the second liquid, of more powerful affinity, which displaces the other, is equal to the pressure of the column of mer- cury required to force the latter through the porous substance. If we tie over one end of a cylindrical tube with a very thin membrane, saturated with concentrated brine by steeping for 24 hours, and if we dry the outer sur- face of the membrane carefully with bibulous paper, and now pour a few drops of pure water into the tube so as just to cover the inner surface of the membrane, the outer surface is seen in a few moments to be cov- ered with minute drops of brine ; that is, brine flows out of the pores of the bladder. A thick ox-bladder, saturated with oil, exhibits the same phenomenon in contact with water. The oil is 168 UNEQUAL ATTRACTION OF MEMBRANES expelled from the pores of the bladder by the water, which occupies its place. Explanation. When the bladder is brought in contact with pure water, it takes up a certain quantity of that liquid. If its pores are previously filled with brine, and if we cover one side of it with pure water, the water mixes with the brine in the pores of the bladder ; and on the side next the water there is formed a diluted brine, which, being in contact with a stratum of pure water, mixes with it, and in this way the successive strata of water receive, from the bladder outwards, a certain quantity of salt. In the interior of the bladder, there are formed in like manner, towards the outer surface, mixtures of unequal saline strength. If we suppose the bladder to consist of several strata, all these strata receive, from the surface in contact with the water, a certain quanti- ty of water ; the outer stratum, in contact with the air, receives least, and is the most highly charged with salt. The cause of mixture is the chemical affinity of the salt for the newly added particles of water ; this affinity is equal on both sides, but the attraction of the sub- stance of the bladder is stronger for the more aqueous or less saline liquid than for the more concentrated. In consequence of this difference in the attraction of the liquids for the substance of the bladder, a part of the mixture is displaced from the bladder ; the less saline liquid takes the place of the more saline ; a part of the latter is expelled, and with it a part of that water which has been added to the outer stratum by mixture. Brine and water flow out .in the direction of least resistance. The efflux towards the side on which the pure water was poured is prevented by the stronger attraction of the more watery liquid for the substance of the bladder. FOR DIFFERENT LIQUIDS. 169 If we remove from the outer surface of the bladder the displaced saline liquid (which has been mixed with some water), and put stronger brine in its place, and if on the opposite side we remove the very diluted solu- tion, replacing it by a still more diluted one, the same process is repeated. There arises a permanent differ- ence, and a state of mixture and efflux continues till the liquids on the opposite surfaces of the bladder have the same, or very nearly the same, composition. If we suppose that the two liquids moisten the blad- der unequally, it follows, that, in addition to the chem- ical attraction which the dissimilar particles of the liquids have for each other, a new cause, namely, the stronger attraction of one of them for the substance of the partition, is introduced, which accelerates their mo- tion or passage, and must have this effect, that one of them flows out in larger quantity, in the same time,, than the other. The experiments (Fig. 3) elucidate this process, and Mixture es- . ,> T.I sentially de- show besides, that the exchange of the two liquids on termined by both sides of the bladder is essentially determined by dena!ty < of their unequal specific gravities. As long as the differ- ence in their composition (which may here be meas- ured by the specific gravity) is very great, the change of volume (increase of one and decrease of the other) takes place rapidly ; but at last, when this difference becomes very small, the liquids mix without further visible change of volume, obviously, because the at- traction of the bladder to the mixtures on the opposite sides does not perceptibly differ, although the specific gravities are still somewhat unequal. In the ultimate result, the action of dissimilar liquids The action of on the substance of animal tissues, in consequence of upon 'animal which their mixture is attended with a change of vol- equivalent ume, appears to be equivalent to a mechanical press- changeki 15 170 THE ATTRACTION OF LIQUIDS FOR MEMBRANES procure un- ure, which is stronger from one side than from the equal on op , posite sides. Other. If the tube (Fig. 9), which is closed with bladder at its wide opening, be filled with brine to the mark a, if so much mercury be then poured into the narrow vertical part as by its pressure to cause brine to begin to flow out in fine drops from the pores of the bladder, and if now, after removing so much of the mercury that the efflux is no longer visible, we place the apparatus in a vessel with pure water, colored blue, as in the figure, the mercury = does not change its level ; and when, after one or two hours, we carefully remove the tube from the water, we find that in the upper part of the wide end of the tube, which contained colorless brine, a dark blue stra- tum has been formed, which floats on a colorless liq- uid. After a longer time, the blue color spreads grad- ually downwards, till at last the brine acquires a uni- form blue tint. It will readily be perceived, that the two liquids here mix, as if no pressure had been applied to the brine, for a mechanical pressure exerts no influence on the mixture ; but, in consequence of the pressure, the mix- ture takes place without change of volume. The me- chanical pressure which the water, in virtue of its stronger affinity for the bladder, exerts on the brine in the pores of the bladder, is held in equilibrium by the column of mercury, and the result is, that exactly as much brine flows out as water flows in. IS EQUIVALENT TO A MECHANICAL PRESSURE. 171 Let us suppose the column of mercury to be re- Additional P , . . . , example. moved, and the rise of the brine in the narrow tube is explained at once. If we close a short tube, filled with alcohol or brine, with bladder at both ends (an arrange- ment which may represent a cell), and suspend it in a vessel of pure water, both surfaces of the bladder be- come convex outwards ; they swell, but without burst- ing. As soon as the pressure, gradually increasing by the influx of water into the interior of the tube, is suf- ficient to keep in equilibrium the affinity of the water for the bladder, and consequently its further influx, the exchange goes on, for the future, without change of volume. Most porous bodies exhibit the phenomena described Porous boti- ,. ' , . . ies generally in the preceding pages, if their pores are so minute exhibit sim- , ilar phenom- that a feeble hydrostatic pressure is not propagated ena. through them. These phenomena may be produced with clay cells * (such as are used for galvanic appa- * I consider it of sufficient importance to state here that po- Among liquids ab- rous clay also takes up unequal volumes of brine and water. S0 rbed by In special experiments made on this subject, cells of clay (mod- ^g"| S a bak " erately ignited porcelain biscuit) were laid for 24 hours in pure water, then carefully dried externally with bibulous paper, and the increase in weight, that is, the weight of the absorbed water, carefully determined. The clay was then carefully dried, laid for 24 hours in brine, and the weight of the absorbed brine de- termined in like manner. In a second series of experiments, the clay cells were steeped in water and brine, and placed in the receiver of the air-pump, under a pressure of 8 lines of mer- cury (fds of an inch) for 24 hours. Under the ordinary pressure, and in air, the cells absorbed Weight. Volume. Water. Brine. Water. Brine. 100 parts of clay cell I. 15 4 14.6 15.4 12.2 II. 11.8 11.6 11.8 9.7 In vacuo, the cells of clay absorbed Weight. Volume. Water. Brine. Water. Brine. 100 parts of clay cell absorbed I. 16.5 16.8 16.5 14.0 II. 13.8 13.8 13.8 11.5 172 ACTION OF LIQUIDS ON THE ratus) ; with the lining membrane of the pods of peas and beans ; with the fine inner bark of trees ; with the skin of grapes, of potatoes, of apples ; with the inner membrane of the capsules of bladder senna, &c. ; but animal tissues surpass all others in efficacy. Besides their unequal affinity, they have an unequal absorbent power for dissimilar liquids, by which their action in causing change of volume during mixture is strength- ened. Effect when When a tube, closed with bladder, and filled with SnunersetHn wa ^r, is immersed in alcohol or brine, there is pro- brine or aico- duced at all points, where the brine or the alcohol comes in contact with bladder saturated with water, a change in the properties of the bladder. When, in the open pores, the alcohol or brine mixes with the water already there, the absorbent power of the bladder for the water is diminished ; a smaller volume of the mix- ture is retained than of pure water; that is to say, water flows out in the direction of the alcohol or brine. This efflux is accompanied by a change in the volume of the substance of the bladder, for that side of it which is towards the alcohol or the brine contracts or shrinks. The opposite surfaces of an animal membrane, in contact with dissimilar liquids, for which they have un- equal absorbent power, are in an unequal state of con- traction. This condition is permanent, as long as the liquids do not change in their properties ; but it ceases in consequence of mixture, and is again restored when, by means of the change of place in both the liquids which are in contact with the opposite surfaces of the bladder, the original or any other permanent inequality or difference of properties is produced. Change in ^ n a ^ cases where a permanent change in the vol- of iwoHqulds ume f two liquids, separated by a membrane, is ob- MEMBRANE SEPARATING THEM. 173 served during their mixture, it is always accompanied separated by a permanent difference in the nature or properties brane is ac- of the two liquids ; and from this it follows, that the ^continual molecules of the animal membrane must be, during the ^cmg the mixture, in an alternate state of contraction and swell- ing, or dilatation ; that is, in a continual motion. From what has been stated, it appears that the and depends ..,,,.., upon the un- change of volume of two miscible liquids, separated by equal anrac- . lion of the a membrane, is determined by the unequal capacity of membrane being moistened, or the unequal attraction of the mem- liquids. brane for these liquids. The unequal absorbent power of the membrane for these liquids depends on the dis- similar nature of the liquids or of the substances dis- solved in them. An unequal proportion of the same dissolved matters (unequal concentration) acts in many cases just as if the liquids contained dissimilar substan- ces. Although the experiments hitherto instituted, and the results obtained by Fischer (who first observed these phenomena), Magnus, Dutrochet, and others, admit of no comparison, since the apparatus used by them showed only relative change of volume, yet a knowl- edge of some of these results is nevertheless of impor- tance. When the two liquids are diluted sulphuric acid (of Effect of sp. g. 1.093) and water, the acid, at 50 F., increases in volume ; but if the acid have the specific gravity 1.054, the volume of the water increases. Diluted tartaric acid (11 parts of the crystallized acid and 89 of water) arid water mix through a bladder without change of volume; with more than 11 per cent, of acid, the volume of the acid increases ; with less, that of the water. Solutions of animal gelatine, gum, sugar, and albu- men increase in volume when separated by a bladder 15* 174 CHANGE OF VOLUME IN LIQUIDS. from water ; and the increase of volume in these dif- ferent solutions, although of the same specific gravity, is very different indeed. When the specific gravity is 1.07, the increase in volume of the solution of gelatine amounts to 3, that of solution of gum to 5, of sugar, 11, of albumen, 12. When a solution of sugar (1 part of sugar to 16 of water) is separated by a bladder from water, it increases in volume ; but if we add 1 part of oxalic acid to the sugar, the water, on the contrary, increases in volume. If the amount of sugar in the so- lution be doubled, the liquids mix without change of volume. A solution of sugar, separated by bladder from one of oxalic acid, rises, in the same time, 3 times higher than when separated from water. (Dutrochet.) Membranes From these experiments we obtain, as a universal have less . . power of ah- result (which, however, requires confirmation), that an sorbing solu- . . . , tionofaibu- animal membrane possesses a less power or absorption ail other sub- for solution of albumen than for all other organic sub- stances ; and that a small amount of mineral or organic Effect of add- acids increases the power of transudation of water, as well as of the solutions of many organic substances.* Causes which The rapidity of mixture of two liquids, separated by pidity of a membrane, depends on the thickness of the mem- brane, and stands in direct proportion to the velocity with which the mixture formed in the pores and on both surfaces of the bladder changes its place, and the orig- * In order not to be misled in such experiments, we must avoid the employment of all those liquids which alter the mem- brane in its chemical properties. Such are, for example, acids of a certain concentration, nitrate of silver, salts of lead, chlo- ride of gold, chloride of tin, chromic acid, bichromate of potash, tannic acid, &c. Even in water, the properties of membranes generally undergo a change after some days ; they then propagate a far weaker hydrostatic pressure through their pores, and are no longer fit for such experiments. CAUSES OF ABSORPTION. 175 inal difference in the quality, of the two liquids is re- newed. If we suppose a tube, formed of a membrane (an in- Action of in- testine, for example), and filled with water, and if we assume that a current of saline solution flows round this tube, in consequence of a mechanical force, the increase of volume of the brine (the passage into it of a certain amount of water) will be effected in a far shorter time than if the brine were not in motion. The velocity of transference will diminish with the Transference , diminishes amount of difference in properties between the two with the dif- , - , . v ference of liquids (the different amount or percentage of salt) ; properties it will be greatest at first n and diminish as the dilution nqJidT l of the brine increases, in proportion, that is to say, as water is transferred from the contents of the tube to the liquid without. The greatest effect, therefore, must occur and be per- Tbe greatest manent, when the water transferred to the brine is con- ^^ the Urs tinually again removed from it, that is, when the con- JJn^bXST centration of the brine is kept uniform. To this end, if JJ r m ptun ' we suppose the membrane to be difficultly permeable for one liquid, while the other is easily taken up into its pores, and if we reflect that this second liquid, on en- tering into the pores of the bladder, in virtue of the at- traction of their walls for it, acquires a certain velocity which permits it to pass beyond the extremities of the canal or of the pores, so as entirely to fill the pores, and to come in direct contact with the liquid on the out- side of the pores, it follows, that, when this second liquid moves past the pores with a certain velocity, the absorbed liquid must follow it during the mixture, and there must take place a rapid transference of the sec- ond liquid to the first, a true suction, as if by a pump. The animal body is an example of an apparatus of The animal this kind in the most perfect form. The bloodvessels P aratu" ap 176 EFFECTS PRODUCED BY DRINKING contain a liquid for which their walls are, in the normal state, far less permeable than for all the other fluids of the body. The blood moves in them with a certain velocity, and is kept at all times in a nearly uniform state of concentration by a special apparatus, namely, the urinary organs. Absorption The whole intestinal canal is surrounded with this of the liquids into the in- system of bloodvessels, and all the animal fluids, in testmes from * the blood. so far as they are capable of being taken up by the parietes of the intestinal canal, and of the blood- vessels situated around it, are rapidly mixed with the blood. The volume of the blood increases, if no com- pensation is effected by means of the kidneys ; and the intestine is emptied of the liquids contained in it. The intestinal glands, through which this transference is effected, and each of which represents a similar appa- ratus of suction, contain, within them, two systems of canals, bloodvessels and lacteals; the bloodvessels are placed next to the external absorbent surface, the lacteals chiefly occupy the central part of the gland. The liquids circulating in these two systems have very unequal velocities, and as the blood moves much faster in the bloodvessels, we perceive how it happens that the fluids of the intestine are chiefly (in quantity and in velocity) taken up into the circulation. Effects pro The difference in the absorbent power of the parietes organism by of the intestinal canal for liquids which contain unequal saline soiu- amounts of dissolved matters is easily observed in the effects produced on the organism by water and saline solutions. If we take, while fasting, every ten minutes, a glass of ordinary spring water, the saline contents of which are much less than those of the blood, there occurs, af- ter the second glass (each glass containing 4 ounces), an evacuation of colored urine, the weight of which is WATER AND SALINE SOLUTIONS. 177 very nearly equal to that of the first glass ; and after taking, in this way, 20 such glasses of water, we have had 19 evacuations of urine, the last of which is color- less, and contains hardly more saline matter than the spring water. If we make the same experiment with a water con- Drinking sea- taining as much saline matter as the blood (f to 1 per cent, of sea salt), there is no unusual discharge of urine, and it is difficult to drink more than three glasses of such water. A sense of repletion, pressure, and weight of the stomach point out, that water as strongly charged with saline matter as the blood requires a long- er time for its absorption into the bloodvessels. Finally, if we drink a solution containing rather more Solutions salt than the blood, a more or less decided catharsis en- more sait g than the blood. The action of solution of salt is of three kinds, ac- cording to the proportion of salt. Spring water is taken up into the bloodvessels with great rapidity ; while these vessels exhibit a very small power of absorption for water containing the same proportion of salt as the blood does ; and a still more strongly saline solution passes out of the body, not through the kidneys, but through the intestinal canal. Saline solutions and water, given in the form of ene- Enemata in ........ . ._ water act as mata, exhibit similar phenomena in the rectum. Pure saline soiu- water is very rapidly absorbed, and excreted through the urinary passages. If we add to the water colored or odorous matters, these appear more or less changed in the urine. When a small quantity of ferrocyanide of potassium is added, its presence in the urine is very soon detected by chloride of iron, which forms with it Prussian blue. Of concentrated solutions, far less is ab- sorbed in the same time than of diluted ; in most cases, they mix with solid matters collected in the rectum, and are expelled in the form of a watery dejection. 178 MEMBRANES PROBABLY EXERT Action of All salts do not act alike in this respect. In equal Glauber and , . Epsom salts doses, the purgative action of Glauber salt and Epsom with that of salt is far stronger than that of sea salt ; and their power of being absorbed by animal membranes appears to be in the inverse ratio of this effect. It is hardly necessary particularly to point out that an explanation of the action of purgatives in general cannot be included in the above- described action of saline solutions on the organism. The example which has been given is intended to illus- trate a physical property common to a large number of salts, and apparently independent of the nature of the acid or base of the salt ; for chloride of calcium, chlo- ride of magnesium, bitartrate of potash, tartrate of potash and soda, phosphate of soda, and certain doses of tartar emetic, show the same action as sea salt, Glauber salt, and Epsom salt, although the bases and acids in these different salts are not the same. Solutions of cane sugar, grape sugar, sugar of milk, and gum, exhibit, when separated from water by an animal membrane, phenomena similar to those exhibited by the above-named solutions of mineral salts, without causing in the living body a purgative action, when of equal concentration. The cause of this difference may be, that the mineral salts, in their passage through the intestinal canal and through the blood, are not essential- ly altered in their composition, while these organic sub- stances, in contact with the parietes of the stomach, and under the influence of the gastric juice, suffer a very rapid change, by which the action which they have out of the body is arrested. Since the chemical nature and the mechanical char- acter of membranes and skins exert the greatest influ- ence on the distribution of the fluids in the animal body, the relations of each membrane presenting any peculi- arity of structure, or of the different glands and systems AN IMPORTANT INFLUENCE ON SECRETIONS. 179 of vessels, deserve to be investigated by careful experi- ment ; and it might very likely be found, that, in the secretion of the milk, the bile, the urine, the sweat, &c., the membranes and cell-walls play a far more impor- tant part than we are inclined to ascribe to them ; that, besides their physical properties, they possess certain chemical properties, by which they are enabled to pro- duce decompositions and combinations, true analyses ; and if this were ascertained, the influence of chemical agents, of remedies, and of poisons on those properties would be at once explained. The phenomena described in the preceding pages are Thephenom- observed, not in the gelatinous tissues alone, but also, fined to the apparently, in many other structures of the animal body, ussues U * which cannot be reckoned as belonging to that class. If we tie moist paper over the open end of a cylindri- Coagulated . . . albumen acts cal tube, and, after pouring in above the paper white of like thin . 7 membrane. egg to the height of a few lines, place that end of the tube in boiling water, the albumen is coagulated, and when the paper is removed, we have a tube closed with an accu- rately fitting plug of coagulated albumen, which allows neither water nor brine to run through. If the tube be now filled to one half with brine, and immersed in pure water, as in Fig. 4, the brine is seen gradually to rise ; and in three or four days it increases by from J to of its volume, exactly as if the tube had been closed with a very thick membrane. Influence of the Cutaneous Evaporation on the Motion of the Fluids of the Animal Body. When a tube, about 30 inches long, bent in the form influence of cutaneous of a knee, and widened at one end, is tied over at that evaporation . . on the motion end with a piece of moist ox-bladder, the bladder now of the animal thoroughly dried, and the tube filled with mercury and JU inverted, so that the open narrow end stands in a cup 180 INFLUENCE OF THE CUTANEOUS Experi- ments. of mercury, the mercury in the tube falls to about 27 inches (Hessian), and remains, if the bladder have no flow, at that height, rising and falling as the mercury does in a barometer. No air passes through the dry bladder into the Torri- cellian vacuum thus produced. When, by proper ma- nipulation, we have allowed to pass out as much as can be removed of the air still contained in the tube, we have in this arrangement a barometer, containing no more air than would be found in one made with a simi- lar tube hermetically sealed at the wide end, provided the mercury in the latter had not been boiled in the tube to expel the last traces of air. By the desiccation of the bladder, its pores, which allowed a passage to water, brine, oil, or even mercury, have obviously been closed by the adhesion of the successive layers of mem- brane, which perhaps cross each other, so that the bladder is not more permeable for the particles of air than a slice of horn of the same thickness. If we introduce wa- Fig< 10 . ter into the tube in the position Fig. 10, to the line marked Z>, and, after filling the narrow part of the tube with mercury, invert it in a vessel of mercury, Fig. 11, we observe a number of minute bubbles of air passing through the moist bladder into the tube. The mer- cury falls to a certain point, which is higher Fig. 11. EVAPORATION ON THE MOTION OF THE FLUIDS. 181 or lower according to the thickness of the bladder ; it stands at a lower level with a thin membrane than with a thick one. When a single layer of ox-bladder is used, it falls to 12 inches (above the level of the mercury in the vessel) ; with a double layer, it stands at from 22 to 24 inches. If we take care to allow the water standing above the mercury to enter the wide part of the tube, so that the bladder is kept at all times covered with water, the mercury remains stationary at the same level. If, for example, it stood at 12 inches, it remains there, al- though the quantity of water is constantly diminishing by evaporation from the bladder ; and it maintains its level, even after all the water has disappeared. The height of the mercury in the narrow tube is an exact measure of the pressure acting on the surface of the bladder. The pressure in the inside of the tube is less than the existing pressure of the atmosphere outside by the height of that column of mercury. This difference of level between the mercury in the vessel and that in the tube is the limit of the pressure under which air passes into the water through the pores of the bladder ; or under which the molecules of water in the pores are displaced by the molecules of air. If we fill the tube entirely with water, and place the narrow end in mercury, while the wide end, closed with bladder, is exposed to the air, the mercury rises in the narrow limb, and at last reaches a point identical with that to which it fell in the preceding experiment. For each specimen of bladder, according to its thickness, the level to which the mercury reaches is of course dif- ferent. When the diameter of the wide part of the tube, which is closed with bladder, is 12 millimetres, and that of the narrow tube 1 millimetre, the mercury rises, with 16 182 EVAPORATION THROUGH MEMBRANES. ox-bladder, according to the temperature and the hy- grometric condition of the air, to from 22 to 65 milli- metres in one hour. The cause of the rise of the mercury in this experi- ment hardly requires a special explanation. Explanation. The bladder is penetrated with water, covered on one side with water, and on the other in contact with a space (the air) not saturated with aqueous vapor. The water contained in the pores of the side of the bladder turned towards the air evaporates ; the space which it had occupied in the pores is filled with successive por- tions of water from within, in virtue of the attraction of the substance of the pores for water. The volume of the water in the tube diminishes, and thus a vacuum arises, in which the mercury is forced to rise by the at- mospheric pressure. The space formerly occupied by the water which has evaporated is now filled with mer- cury. When the mercury has reached a permanent level, the external pressure, which acts on the water in the pores of the bladder (and which tends to displace the particles of water) is obviously equal, before air enters, to the attraction which the substance of the bladder has for the particles of water, and these last to each other. Were the attraction less, air would enter, and the parti- cles of water could not maintain their position. The rise of the mercury, or its motion towards the surface of the bladder, that is, towards the point where evaporation is going on, is the result of a difference of atmospheric pressure, determined by the evaporation of the water, or of the liquid which penetrates through the bladder, and by the absorbent power of the bladder for that liquid. One chief condition of the efficiency of a bladder, in regard to the rise of a column of liquid, is, that it is kept INFLUENCE OF THE PRESSURE OF THE AIR. 183 constantly in contact with the liquid, for without this contact the absorbent power cannot manifest itself. By the evaporation, a continual efflux of water, in the form of vapor, towards the side on which the air lies, is produced ; and by the capillary action of the bladder on the other side, water is absorbed and retained with a force which counterpoises 12 or more inches of mercu- ry, according to the thickness of the bladder. Now, since the rise of the mercury is an effect of the Dependence atmospheric pressure, it is plain that the height to which state of the , . IT, -1 barometer. the mercury rises must depend to a certain degree on the state of the barometer. In a tube, filled with water, and closed with bladder, the absorbent force of which is equal to the pressure of a column of 12 inches of mercury, the mercury rises by evaporation to the height of 12 inches, as long as a column of 12 inches of mercury can be sustained by the external atmospheric pressure. If this external pressure fall below that limit, the mercury in the evap- oration tube falls to the same extent, and if there be water above the mercury, this water separates from the bladder. This property of bladder, therefore, would appear unaltered at an elevation at which the barometer should stand at 12 inches ; at a still greater elevation, on the contrary, the liquid would separate from the bladder. The external pressure has no influence on the The pressure . . ... , of the air has amount or the water evaporating in the pores or the no influence bladder ; that amount depends on the hygrometric state amount of of the surrounding air, and on the temperature. In a ev rarefied air (provided it can take up moisture), evap- oration goes on more rapidly than in a denser air ; and hence it is clear, that, at certain elevations, the effect of the bladder on the level of the liquid is more quickly produced than at the level of the sea. The amount of 184 WATER PASSES MORE EASILY water which evaporates is directly proportional to the surrounding space, and to the temperature and corre- sponding tension of the liquid. When the tube, Fig. 10, is filled with water to Z>, then entirely filled with mercury, and inverted in mer- cury, the mercury, as we have seen, assumes a fixed level. If now we keep the upper or wide end of the tube, which is closed with bladder, immersed in a ves- sel of water, Fig. 12, we shall Fig. 12. find, after a short time, that the mercury sinks in the narrow tube. If its level has been 12 inches above that of the mer- cury in the vessel, it sinks when the bladder is put into water, 3 or 4 inches for exam- ple, and remains stationary at 8 or 9 inches, without sinking further for the next 12 hours. The sinking of the mercury is caused by water being forced through the bladder into the tube, in virtue of the existence of an external pressure greater than the pressure on the inside of the tube. To displace the aqueous particles in the pores of the Permeability bladder by other aqueous particles requires obviously a of bladder t 11 .if greater to much smaller pressure than is necessary to displace tTafr. ' them by particles of air. In the one case, where both surfaces of the bladder are in contact with the liquid, the attractive force (that of the bladder for the water and of the water for the bladder) is equal on both sides ; but not so in the other case, where one side of the bladder is in contact with air. If the bladder had the same absorbent power for the particles of air as for THAN AIR THROUGH MOIST MEMBRANES. 185 those of water, the particles of air and water would pass through the bladder under the same pressure ; the experiment shows, that the absorbent power and permeability of the bladder for air are far less than for water. Hence it comes to pass, that when, with a given portion of bladder, in the apparatus, Fig. 11, mercury is raised by evaporation to a height of 12 inches, less than 12 inches of mercury are required, in the apparatus, Fig. 1, to cause water to pass through the bladder. Fig. 13. When the tube (Fig. 13) is filled with Experiments water, closed with bladder at both ends, clo^edatboth and exposed to evaporation, the bladders membrane; in a short time become concave, that is, they are pressed inwards. As the evap- oration of the water through the moist surfaces of the bladder proceeds, there is formed in the upper part of the tube a vacuum, which is filled with aqueous va- por, and which continues to increase. The place of the water which evap- orates is, as in the experiments previously described, gradually occupied by air, which enters the tube through the bladder. It is evident, that when air enters the tube (Fig. 13), the pressure on the surface of the bladder is equal to the absorbent force of that bladder for the water. In the apparatus, Fig. 11, with the same bladder, the mer- cury might have been raised, in consequence of the evaporation, to a height of 4, 6, 12, or more inches, according to the thickness of the membrane. When the longer limb of the bent tube, after it with one end has been filled with water, and closed at both ends tube filled with bladder, is placed in a vessel containing brine, and exposed to evaporate in the air, as in Fig. 14, 16* 186 EVAPORATION THROUGH MEMBRANES. with one end of the tube in bile ; with one end in oil. Effect of a series of short tubes, closed at both ends with membrane, and connect- ed with each other. Motion of liquid is toward the surface from which evap- it is plain that when the atmospheric pressure, increasing in consequence of the evaporation of the water on both the surfaces of the bladder, reaches the point at which the brine flows through the pores of the bladder, then the place of the water which evaporates is occupied by brine. In fact, when the brine is colored blue, we observe, after a few hours, that a blue stratum forms within the tube, which constantly increases, till at last the vessel of brine is emptied, and the tube is entirely filled with brine. If the longer limb be immersed in bile instead of brine, the tube fills with bile, and if we employ, for closing one end, a membrane rather thinner than we use for the other, from which the evaporation takes place, and then place the end with the thinner mem- brane in oil (oil of marrow), the tube gradually fills with oil. In all these cases, no air enters the tube, which con- tinues full of liquid, as it was at first. If we connect the evaporation tube by collars of caoutchouc with short bits of tube (Fig. 15), full of water, and tied with bladder at both ends ; and if we immerse the last bit of tube in brine, urine, oil, &c., all these cells, and at last the evapora- tion tube itself, become gradually filled with brine, urine, oil, &c. The most general expression for these experiments and results is this ; that all liquids, which are in con- Fig. 15. IMPORTANCE OF CUTANEOUS TRANSPIRATION. 187 nection with a membrane from the surface of which oration takes evaporation can take place, must acquire motion towards p that membrane. The amount of this motion is directly proportional to the rapidity of evaporation, and consequently to the temperature and hygrometric state of the atmosphere. That the skin of animals, and the cutaneous tran- influence of spiration, as well as the evaporation from the internal cutan^ou s and surface of the lungs, exert an important influence on ^n^h? 1 ^ the vital processes, and thereby on the state of health, health - has been admitted by physicians ever since medicine has existed ; but no one has hitherto ascertained pre- cisely in what way this happens. From what has gone before, it can hardly be doubt- The cmane- . . ous evapora- ed, that one of the most important functions of the tion has an , . i i i i i i important skin consists m the share which it takes in the motion share in caus- and distribution of the fluids of the body. tion oAhe The surface of the body of a number of animals consists of a covering or skin permeable for liquids, from which, when, as in the case of the lung, it is in contact with the atmosphere, an evaporation of water, according to the hygrometric state and temperature of the air, constantly goes on. If we now keep in mind, that every part of the body has to sustain the pressure of the atmosphere, and that the gaseous fluids and liquids contained in the body oppose to this pressure a perfectly equal resistance, it is clear, that, by the evaporation of the skin and lungs, and in consequence of the absorbent power of the skin for the liquid in contact with it, a difference in the press- ure below the surface of the evaporating skin occurs. The external pressure increases, and in an equal de- gree the pressure from within towards the skin. If now the structure of the cutaneous surface does not permit a diminution of its volume, a compression (in 188 EFFECTS OF CUTANEOUS EVAPORATION. consequence of the loss of liquid by evaporation), it is obvious that an equalization of this difference in press- ure can only take place from within outwards ; first from within, and especially from those parts which are in closest contact with the atmosphere, and which offer the least resistance to the action of the external pressure. Evaporation Hence it follows, that the fluids of the body, in con- causes the fluids of the sequence of the cutaneous and pulmonary transpira- bodytomove . . . . . . ' - towards the tion, acquire a motion towards the skin and lungs, fungs. n which must be accelerated by the circulation of the blood. Change in By this evaporation, the laws of the mixture of dis- the laws of . .,,.., , , , mixture of similar liquids, separated by a membrane, must be es- liquids by sentially modified. The passage of the food dissolved evaporation. .... . i/>ii i in the alimentary canal, and of the lymph into the blood- vessels, the expulsion of the nutritive fluid out of the minuter bloodvessels, the uniform distribution of these fluids in the body, the absorbent power of the mem- branes and skins, which, under the actual pressure, are permeable for the liquids in contact with them, are under the influence of the difference in the atmospher- ical pressure, which is caused by the evaporation of the fluids of the skin and lungs. Effects of dry The juices and fluids of the body distribute them- and I of 1 eieva' selves, according to the thickness of the walls of the vessels, and their permeability for these fluids, uni- formly through the whole body ; and the influence which a residence in dry or in moist air, at great ele- vations or at the level of the sea, may exert on the health, in so far as the evaporation may thus be accel- erated or retarded, requires no special explanation ; while, on the other hand, the suppression of the cuta- neous transpiration must be followed by a disturbance of this motion, in consequence of which the normal process is changed where this occurs. EFFECTS OF CUTANEOUS EVAPORATION. 189 The pressure, which, in consequence of the evapora- The pregsure tion, urges the fluids within the body to move towards ]j[^s g the the skin, is, as may readily be understood, equal to g^Jf^enoai the difference of pressure acting on the surface of the ure acting on the sur- From the experiment, Fig. 13, it is plain, that when ^ of lhe one of the two surfaces of bladder at the ends of the tube, Fig. 12, is exposed to atmospheric evaporation, while the other end is moistened with water, brine, or 011, these liquids are rapidly absorbed by the mem- brane, that is, are forced in by the external atmos- pheric pressure, and it is not less obvious, that the same thing takes place with the liquid with which one of the two evaporating surfaces has been moistened in the middle only ; while the evaporation continues around the moistened spot. If, therefore, we moisten with a liquid the surface of if we moisten .,1 ,. -, . . , Al v .j . /. j the skin, the the evaporating skin at any point, the liquid is forced liquids are inwards by the external pressure. externa 1 / 1 Let us suppose any part of the skin to be rubbed pre with fat, the transpiration ceases at that part. If now Rubbed with the skin around the part is in its normal activity, if, cease^to 8 ^ 111 therefore, in the surrounding parts liquid is constantly trans P ire - passing off by evaporation, the fat must be urged, by the unequal pressure thus arising, towards these parts, or it is absorbed, just as water, in the apparatus, Fig. 12, is absorbed, when in consequence of evaporation a difference between the internal and external pressure has arisen. If the whole skin were covered with fat, the absorption would be effected by the pulmonary evaporation. The blistering of the skin, and the sun-burning, to which men are exposed at great elevations, arise from the extraordinary dryness of the air, the increased evaporation, and the pressure by which the fluids filling the vessels are forced towards the surface. 190 EXPERIMENTS OF HALES ON THE causes of the Several causes contribute jointly to the appearance sweat. of the sweat, to the efflux of fluid from the pores of the skin. One of these obviously depends on the ve- locity which the fluid set in motion by evaporation or by a mechanical cause acquires from the accelerated motion of the blood. In consequence of this velocity, the fluid moves out beyond the limits of the absorbing membrane or skin. Fishes die in The changes of the vital process, caused by the un- causethedue equal distribution of fluid in the body in consequence distribution f . . J . ?. of the fluids of evaporation, are best seen m animals which live in water, in whom, therefore, the above explained cause of motion in the normal state does not act. When a fish is held immersed in water, so that the head is out of the water, while the rest of the body is covered, it dies in a few minutes. It dies exactly in the same way when head and gills are held in the water, and the body in air (Milne Edwards) ; in both cases, with- out loss of weight. This fact shows that even if the weight of the animal be kept unaltered by the absorp- tion of water through the body kept in that medium, yet the distribution of the fluids in the body does not take place in the proportion necessary for the preserva- tion of their vital functions. The fish dies. Experiments It i s hardly necessary to remind the reader, that the by Hales on m J t \ the motion of experiments described in the foregoing pases, in so the sap in plants. far as they permit us to draw conclusions as to the cause of the motion of the juices of the animal body, agree in all respects with the observations made on plants by Stephen Hales more than 120 years since. The experiments of Hales on the mechanism of the motion of the sap may stand as a pattern to all times of an excellent method. That they remain, to this moment, unsurpassed in the domain of vegetable phys- iology, may be perhaps explained by the fact that MOTION OF THE SAP IN PLANTS. 191 they date from the age of Newton. They ought to be familiar to every vegetable physiologist. In the beginning of his work, Hales describes the experiments which he made on the motion of the sap in plants in consequence of their evaporation in branch- es covered with foliage, in cut plants as well as in those still provided with roots. He shows by the following experiment the influence influence of of the mechanical pressure of a column of water, with of a column ,> f water, and without the help of evaporation. with and .-T, t n i i without the To a branch of an apple-tree bearing its twigs and heipofevap- leaves, Hales fastened, air-tight, a tube 7 feet long. He kept the branch with its twigs and leaves im- mersed in a large vessel of water, and filled the tube with water. By the pressure of the column of water, . water was forced into the branch, and in 2 days the water in the tube had sunk 14 inches. On the third day, he took the branch out of the water, and exposed it to free evaporation in the air. The water in the tube fell, in 12 hours, 27 inches. To compare the force with which water is driven through the vessels of the wood, by pressure alone, with that produced by pressure and evaporation, he joined an apple branch, 6 feet long, with leaves, and exposed to the air, with a tube 9 feet long, which was filled with water. From the pressure caused by the column of water, and by the evaporation going on at the surface of the twigs and leaves, the water fell (Xlth experiment), in one hour, 36 inches. He now cut off the branch 13 inches below the tube, and placed the portion cut off (with the twigs and leaves) vertically in a vessel of water. This last absorbed, in 30 hours, 18 ounces of water, while the portion of wood remaining in con- nection with the tube, which was 13 inches long, only 192 EXPERIMENTS OF HALES ON THE allowed 6 ounces of water to pass, and that under the pressure of a column of 7 feet of water. Demotion Hales shows, in three other experiments, that the ol the fluids caused by the capillary vessels of a plant, alone, and in connection evaporating ... surface alone, with the uninjured roots, are easily filled with water by capillary attraction, without, however, possessing the power of causing the sap to flow out and to rise in a tube attached. The motion of the sap, concludes Hales, belongs to the evaporating surface alone ; he proves that it goes on in an unequal degree from the stem, the twigs, the flowers, and fruit, and that the effect of the evaporation stands in a fixed ratio to the temperature and hygrometric state of the air. If the air were moist, but little was absorbed ; the absorption was hardly perceptible on rainy days. He opens the second chapter of his Statistics with the following introduction : " Having in the first chapter seen many proofs of the great quantities of liquor imbibed and perspired by vegetables, I propose in this, to inquire with what force they do imbibe moisture. Though vegetables (which are inanimate) have not an engine, which, by its alternate dilations and contractions, does in animals forcibly drive the blood through the arteries and veins ; yet has nature wonderfully contrived other means, most powerfully to raise and keep in motion the sap." The force J n his experiment XXL, he exposed one of the chief with which sap is moved roots of a pear-tree in full growth at a depth of 24- in plants feet, cut off the point of it, and connected the part of the root left in connection with the stem with a tube, which he filled with water, and closed with mercury. In consequence of the evaporation from the surface of the tree, the root absorbed the water in the tube with such a force, that in six minutes the mercury rose to 8 inches in the tube. This corresponds to a column of water 9 feet high. MOTION OF THE SAP IN PLANTS. 193 This force is nearly equal to that with which the blood moves in the great femoral artery of the horse, and blood iu Hales, in his experiment XXXVI., found the force of ar the blood in various animals : " By tying those sev- eral animals down alive upon their backs, and then laying open the great left crural artery, where it first enters the thigh, I fixed to it (by means of two brass pipes which run one into the other) a glass tube of above 10 feet long, and ^-th of an inch in diameter in bore. In which tube the blood of one horse rose 8 feet 3 inches, and the blood of another horse 8 feet 9 inches. The blood of a little dog, 6 feet high." Hales showed, by special experiments, that the ab- sorbent force which he pointed out in the root is found also in the stem, in each separate twig, each leaf, and every part of the surface ; and that the motion of the sap continues from the root towards the twigs and leaves, even when the stem has been entirely stripped of bark, inner and outer. This force acts not only from the roots in the. direction of the summit, but also from the summit in the direction of the root. From his experiments he deduces the presence of a powerful attractive force, residing in every part of the plant. We now know, that this attractive force, as such, This force is ,., . . atmospheric did not cause the rise of the mercury or water in his pressure, tubes, and it appears clearly from his experiments, that the absorbent power of plants, of each leaf, of each fibre of the root, is sustained by a powerful ex- ternal force, which is nothing else than the pressure of the atmosphere. By the evaporation of water at the surface of plants, A partial ! i . vacuum is a vacuum arises within them, in consequence of which caused wii^i- water and matters soluble in water are driven inwards evaporation. and raised from without with facility, and this external 17 194 EXPERIMENTS OF HALES ON THE pressure, along with capillary attraction, is the chief cause of the motion and distribution of the juices. With respect to the absorbent power of the surface of the plant for gases, under a certain external press- ure, his experiments offer the most beautiful evidence. Hales says, in his experiment XXIL, " This height of the mercury did in some measure show the force with which the sap was imbibed, though not near the whole force ; for while the water was imbibing, the transverse cut of the branch was covered with innumerable little hemispheres of air, and many air-bubbles issued out of the sap-vessels, which air did in part fill the tube e r, as the water was drawn out of it ; so that the height of the mercury could only be proportionable to the excess of the quantity of water drawn off above the quantity of air which issued out of the wood. And if the quantity of air which issued from the wood into the tube had been equal to the quantity of water im- bibed, then the mercury would not rise at all ; because there would be no room for it in the tube. But if 9 parts in 12 of the water be imbibed by the branch, and in the mean time but three such parts of air issue into the tube, then the mercury must needs rise near 6 inches, and so proportionably in different cases." injury of When, in his experiments, the root, the stem, or a plants les . . , , -. /Y sens the twig had been injured at any part, by the cutting on power. en of buds, root-fibres, or small twigs, the absorbent pow- er of the remainder was diminished in a very obvious degree (because, from these places, by the entrance of air the difference of pressure was more easily equal- ized) ; the absorbent power was greatest on freshly- cut surfaces, on which, however, it gradually de- creased, till, after several days, it was not greater in these places than in the uninjured surface of the plant. The evaporation, further argues Hales, is the power- ABSORBENT POWER OF PLANTS. 195 ful cause which provides food for the plant and its Evaporation vicinity. Disease and death of the plant follow, when to the plant. the proportion between evaporation and supply is in- terrupted or destroyed in any way. When, in hot summers, the earth cannot supply, through the roots, the moisture which during the day has evaporated through the leaves and surface of the tree, when the tree, or a twig of it, dries up, the motion of the sap is arrested at these points. When once dried, capillary action alone cannot restore the original activity ; the evaporation is the chief con- dition of the life of plants ; by its means a permanent motion, a continually repeated change in the quality of the juice (sap), is effected. " By comparing," says Hales, " the surface of the Necessity of. J / . cutting off roots of plants with the surface of the same plant branches , . /. /v fr m a trans - above ground, we see the necessity of cutting on many planted tree. branches from a transplanted tree : for if 256 square inches of root in surface were necessary to maintain this cabbage in a healthy natural state, suppose, upon digging it up, in order to transplant, half the roots be cut off (which is the case of most young transplanted trees), then it 's plain that but half the usual nourish- ment can be carried up, through the roots, on that ac- count ; and a very much less proportion, on account of the small hemisphere of earth the new-planted short- ened roots occupy ; and on account of the loose position of the new-turned earth, which touches the roots at first but in few points." Hales proves the influence of suppressed evapora- tion by the following observations on hop-vines. u Now there being 1,000 hills in an acre of hop- Observations ground, and each hill having three poles, and each pole the blight in three vines, the number of vines will be 9,000 ; each of which imbibing four ounces, the sum of all the 196 OBSERVATIONS OF HALES ON ounces imbibed in an acre in a twelve hours' day will be 36,000 ounces = 15,750,000 grains = 62,007 cubic inches, or 220 gallons; which divided by 6,272,640, the number of square inches in an acre, it will be found that the quantity of liquor perspired by all the hop-vines will be equal to an area of liquor as broad as an acre, and T ^ T part of an inch deep, besides what evaporated from the earth. And this quantity of moist- ure in a kindly state of the air is daily carried off in a sufficient quantity to keep the hops in a healthy state ; but in a rainy, moist state of air, without a due mix- ture of dry weather, too much moisture hovers about the hops, so as to hinder in a good measure the kindly perspiration of the leaves, whereby the stagnating sap corrupts, and breeds mouldy fen, which often spoils vast quantities of flourishing hop-grounds. " This was the case in the year 1723, when ten or fourteen days' almost continual rains fell, about the lat- ter half of July, after four months' dry weather ; upon which the most flourishing and promising hops were all infected with mould or fen, in their leaves and fruit, whilst the then poor and unpromising hops escaped, and produced plenty ; because they, being small, did not perspire so great a quantity as the others ; nor did they confine the perspired vapor, so much as the large thriving vines did, in their shady thickets. This rain on the then warm earth made the grass shoot out as fast as if it were in a hot-bed ; and the apples grew so precipitately, that they were of a very fleshy constitu- tion, so as to rot more remarkably than had ever been remembered. "The planters observe, that, when a mould or fen has once seized any part of the ground, it soon runs over the whole ; and that the grass, and other herbs under the hops, are infected with it. THE BLIGHT IN HOPS. 197 " Probably because the small seeds of this quick- growing mould, which soon come to maturity, are blown over the whole ground Which spreading of the seed may be the reason why some grounds are in- fected with fen for several years successively." "I have in July (the season for fire-blasts, as the Fire-blasts in hops. planters call them) seen," says Hales, " the vines in the middle of a hop-ground all scorched up, almost from one end of a large ground to the other, when a hot gleam of sunshine has come immediately after a shower of rain ; at which time the vapors are often seen with the naked eye, but especially with reflecting telescopes, to ascend so plentifully, as to make a clear and distinct object become immediately very -dim and tremulous. Nor was there any dry, gravelly vein in the ground, along the course of this scorch. It was therefore, probably owing to the much greater quantity of scorching vapors in the middle than outsides of the ground, and that being a denser medium, it was much hotter than a more rare medium. " This is an effect which the gardeners about Lon- don have too often found to their cost, when they have incautiously put bell-glasses over their cauliflowers early in a frosty morning, before the dew was evapo- rated off them ; which dew being raised by the sun's warmth, and confined within the glass, did there form a dense, transparent, scalding vapor, which burnt and killed the plants." When these observations are translated into our pres- ent language, we perceive with what acuteness and ac- curacy Hales recognized the influence of evaporation Hales recog- xi_ T/ f i nized the in- on the hie ol plants. nuenceof According to him, the development and growth of ^tSulfe" the plant depends on the supply of nourishment and of plar moisture from the soil, which is determined by a cer- 17* 198 ORIGIN OF THE POTATO BLIGHT. Decaying juices of plants be- come a fe I'- ll le soil for microscopic plants. Origin of the potato dis- ease is prob- ably similar to that of the blight in hops. The potato disease long known. tain temperature and dryness of the atmosphere. The absorbent power of plants, the motion of their sap, depends on evaporation ; the amount of food neces- sary for their nutrition, which is absorbed, is propor- tional to the amount of moisture given out (evaporated) in a given time. When the plant has taken up a max- imum of moisture, and the evaporation is suppressed by a low temperature or by continued wet weather, the supply of food, the nutrition of the plant, ceases ; the juices stagnate, and are altered ; they now pass into a state in which they become a fertile soil for microscopic plants. When rain falls after hot weather, and is fol- lowed by great heat without wind, so that every part of the plant is surrounded by an - atmosphere saturated with moisture, the cooling due to further evaporation ceases, and the plants are destroyed by fire-blast or scorching (Sonnenbrand, German, literally sun-lurn or sun-blight). After the experience and observations of so long a period in reference to the influence of evaporation on the condition of plants, I hardly think that any unprej- udiced observer can entertain the smallest doubt con- cerning the cause of the great mischief which has be- fallen agriculture during the last few years. If Hales, that unequalled observer and inquirer, had known the potato disease, I hardly believe that he would have as- cribed it to an internal cause belonging to the plant, any more than he thought of ascribing the blight of the hop-plants, formerly mentioned, to a special hop disease, or the rotting of the apples to an apple disease. Even Parmentier, to whom France is indebted for the introduction of the potato, knew this disease, and has very accurately described it. The term " potato-rot " has been known to the oldest peasants and agricul- turists since their youth ; it has, doubtless, only acquired ORIGIN OF THE POTATO BLIGHT. 199 of late years the frightful significance, which seems to threaten the well-being of nations, since the causes, which formerly brought it locally into existence, have spread over whole districts and countries. The writ- ings of Hales bring to our century from a preceding one the consoling certainty (and this is especially im- portant), that the cause of this decay is not to be its great . . prevalence in looked for in a degeneration of the plant, but depends the last few on the combination of certain conditions accidentally pends on the . , til combination coincident ; and that these, when they are well ascertain- of certain i , , . conditions ed and kept in view, enable the agriculturist, if not to accidentally annihilate, at least to diminish, their hurtful influence, and not on The potato-plant obviously belongs to the same class tio e n of^e* of plants as the hop-plant ; namely, to that class which species* 8 ' is most seriously injured by the stagnation of their juices in consequence of suppressed transpiration. Ac- cording to Knight, the tubers are not formed by swell- ing of the proper roots, but by the development of a kind of underground stalks or runners. He found that when the tubers under ground were suppressed, tubers were formed on the stalks above ground ; and it is con- ceivable that every external cause which exerts a hurt- ful influence on the healthy condition of the leaves and stalks must act in like manner on the tubers. In the districts which were most severely visited by the so- called potato disease in 1846, damp, cold, rainy weath- er followed a series of very hot days ; and in 1847, cold and rain came on, after continued drought, in the beginning of September, exactly at the period of the most luxuriant growth of the potatoes. In most places, no trace of disease was observed in the early potatoes before the middle of August ; and even after that period, low-lying, cold, and wet fields were chiefly attacked by it. In many plants, in the same field in which the seed potatoes had been de- 200 EFFECT OF COLD ON PLANTS. stroyed by putrefraction and decay, the tubers appeared quite healthy, while in others it was easy to see that those tubers alone which lay next to the old potatoes were infected and attacked by the disease, and that on the side next to the old tubers. observations In 1846 all the potato-plants in my garden died com- thor. pletely off towards the end of August, before a single tuber had been formed ; and in 1847, in the same field, the tubers of all those plants which stood under trees and in protected spots were quite rotten, while no trace of disease appeared in spots which were more elevated and more fully exposed to the current of air. The cause is The cause of the disease is the same which, in spring the same as . _ - . . .. that which and autumn, excites influenza ; * that is, the disease is enza. es ' u " the effect of the temperature and hygrometric state of the atmosphere, by which, in consequence of the dis- turbance of the normal transpiration, a check is sud- denly, or fbr a considerable time, given to the motion of the fluids, which is one chief condition of life, and which thus becomes insufficient for the purposes of health, or even hurtful to the individual. The whole existence of a plant, the resistance which it opposes to the action of the atmospheric oxygen, is most closely connected with the continued support of its vital functions. The mere alternation of day and night makes, in this respect, a great difference. The sinking of the external temperature by a few degrees causes the leaves to fall in autumn ; and a cold night is followed by the death of many annual plants. * Schonbein has observed that the prevalence of influenza and the presence of ozone in the air are in proportion to each other. Is it yet to be found that there are causes influencing the quantity of this form of oxygen in the air, causes more ener- getic in the last few years than hitherto ? The circumstance, that ozone greatly hastens decay, adds interest to the inquiry. E. N. H. CONDITIONS OF THE LIFE OF PLANTS. 201 If we reflect that a plant, in order to protect itself from external causes of disturbance, or to seek the food which it requires, cannot change its place ; that its normal vital functions depend on the simultaneous and combined action of water, of the soil, of the ex- ternal temperature, and of the hygrometric state of the atmosphere ; that is, on four external circumstances ; The life of i 11 ! i /> /> plants is de- it is easy to comprehend the disturbance of functions pendent which must occur in the organism in consequence of four exter- any change in the mutual relations of so many com- bined agencies. The state of a plant is a sure indi- cation of equilibrium or of misproportion in the exter- nal conditions of its life ; and the dexterity of the ac- complished gardener consists exactly in this, that he knows and can establish the just proportion of these conditions for each species of vegetable. Only one of these numerous conditions is in the power c^the agri- culturist, and that is, the production of the quality of the soil appropriate for the crop, including the necessa- ry modification of its composition, by the mechanical working of the soil ; by the irrigation or draining of his fields ; and lastly, by the employment of manure. When one of the constituents of the soil, which, under only one of ... . - , which, name- the given circumstances, is necessary for the support iy, the quai- of the vital functions, is absent, the external injurious soiijsVthe influence is strengthened by this deficiency. Had this agriculturist 6 constituent been present, the plant would have been enabled to oppose to the external hurtful influences a continued resistance. One day may be decisive as to the life or death of a plant. An accurate knowledge of the influence exerted by the various constituents of the soil on the diseased condition must enable the ag- riculturist to protect and preserve many of his fields for a long time from this destruction ; but it is obvi- ous that a universal remedy against this evil does not exist. 202 RISE OF THE SPRING SAP. Effects of When the vessels of the plant are filled to overflow- suppressed ... evaporation, ing with water, and the motion of the sap is suppressed, the nutrition, in most plants, is arrested, and death takes place. Every one knows the effect of a sudden or of a gradual overfilling of certain parts or organs, when the corresponding evaporation is suppressed. By the endosmotic pressure of the water flowing towards those cells which contain sugar, mucilage, gum, albu- men, and soluble matters in general, the juicy fruits and seeds approaching maturity burst, and the juice of grapes, cherries, plums, &e., passes, on contact with the air, into a state of progressive change. The fungi which have been observed on the potato-plants, and the putrefaction of the tubers, are not the signs of a disease, but the consequences of the death of the plant. of^HaiSon 3 Amono^he most important of the experiments made the rise of by Hales, we must reckon undoubtedly those on the spring sap in / 7 perennial r i s e of the spring sap in perennial plants. His obser- vations have been entirely confirmed by all those who since his time have studied the subject ; but, in my opinion, without our having approached one step nearer to the cause of the phenomena. The most recent experiments on this subject by E. Briicke, leave no doubt in regard to the actual state of our knowledge. Dutrochet According to Dutrochet, it is the extremities of the radical fibres, called by De Candolle spongioles, which effect the rise of the spring sap ; and he believes (L' Agent Immediat du Mouvement Vital, Paris, 1826) that the force with which the sap is driven upwards acts from the root. Dutrochet cut off a piece of a vine- stem, two metres long ; and he saw that the sap flowed steadily from the shortened stem in connection with the root. When he had again cut it off close to the THEORY OF DUTROCHET. 203 ground, he observed that the portion in the ground con- tinued to pour forth sap from the whole cut surface. He pursued the experiment, going deeper every time, and he always found that the sap flowed from the part left in the ground, till at last he came "to the extreme points of the fibres, in which he then located the origin of the moving force. The peculiar activity of the spongioles must, accord- ing to Dutrochet, be ascribed to all the causes, taken together, which determine the phenomena of Endos- mosis. Now that we are better acquainted with the phenom- objections to ena of what is called Endosmosis, we may oppose ofloutrlShet. to this view some well-founded doubts. All observers agree, that the increase in volume of a liquid, separat- ed from another liquid by a porous diaphragm, is de- termined by a difference in the qualities of the two liquids. If their composition and properties be the same, there is no cause sufficient to produce mixture and change of volume, since in this case the attrac- tion of both for the diaphragm and for each other is perfectly equal. In the course of his admirable researches, Briicke Observation t .,of Briicke on determined the specific gravity of the spring sap which the specific had flowed from the vine. He found it, in one plant, spring 7 sap in = 1.0008, and in another, = 1.0009.* These numbers prove irresistibly, that the specific gravity of the sap of the vine is in no way different from that of ordinary spring water, or of the water which has filtered through garden mould. In most cases, spring water contains even more dissolved matter. The spring sap of the vine which had the sp. g. 1.0008 raised a column of mercury to the height of 174 lines (14.5 inche's), and therefore exerted a press- * Poggendorfs Annalen der Physik, LXIII. 177. 204 RISE OF THE SPRING SAP. ure equal to that of a column of water 195 inches high. It is quite impossible to account for this pressure by the difference in the amount of dissolved matter in the water absorbed by the roots, and the sap flowing from the cut surface. In the experiment No. IX. of Briicke, made with a vine the sap of which had the sp. g. 1.0009, the mercury was raised at 7 A. M. to the height of 209 lines (nearly 17.5 inches). No one can doubt that what is called Endosmosis has some share in the rise of the sap of the maple and birch trees, which is proportionally rich in sugar, and differs materially in composition from spring water, as well as on the flow or exudation of gummy or saccha- rine juices ;. but the pressure exerted in these cases cannot be compared to that exerted by the sap of the vine, where the causes included under the word Endos- mosis cannot act. The cause of It is evident, that the cause of the pressure of the the rise of . . . . the spring spring sap must be transient, called into action by ex- transient, ternal causes, and limited to a short period. The ex- periment of Dutrochet, from which he concludes that the cause of the rise of the sap resides in the extreme points of the roots, may be thus interpreted : " The cause of the efflux and pressure of the sap exists in all parts of the uninjured plant, down to the extreme spongioles of the root." The present season does not admit of experiments on this point; but as spring approaches, it may be proper here to develop more clearly the grounds of the opinion, that the cause of the efflux of the sap of the vine is a transient one. Perhaps some one may thus be induced to decide experimentally all the ques- tions connected with this remarkable phenomenon. Experiments Hales, in his experiment XXXIV., cut off a vine- of Hales. gtem ^ f eet aDOVe the ground, and attached to the trunk EXPERIMENTS OF HALES. 205 tubes of 7 feet long, joined together. Below the cut there were no branches. This was done on the 30th of March, at 3 p. M. As the stem poured out no sap on that day, he poured water into the attached tube to the height of two feet. This water was absorbed by the stem, so that at about 8 P. M. the water had fallen to 3 inches in the tube. The next day, at ^ past 6 A. M., the sap stood three inches higher than at 8 the evening before. From this time the sap continued to rise, till it reached a height of 21 feet. It would perhaps, says Hales, have risen high- er, had the joinings of the tubes been more water tight. Whatever opinion we rnay entertain as to the cause The cause n , m , ... .. , of the motion of the efflux and pressure of the sap, it is impossible of the sap . . , exists not to suppose that the mechanical or any other structure merely in the or quality of the radical fibres, the spongioles, or the SJun 1 ^!?' inner parts of the vine-stem generally, can have pfant. changed so much between the evening of the 30th and the morning of the 31st as to give rise to two com- pletely opposite influences. On the evening of the 30th, the water poured into the tube was absorbed ; on the 31st, it was expelled with a continually increasing force. In his experiment XXXVII., Hales fixed, on three branches of a horizontally trained espalier vine, siphon tubes, filled to a certain point with mercury. The three branches received their sap from the com- mon stem, that stem from the root. The first branch was 7 feet from the second, the second 22 feet 8 inches from the third. The first and third branches were two years old, the middle one was older. From the 4th to the 20th of April, the mercury stood, in consequence of the pressure of the sap, high- er in the open limb of the tubes than in the other, which was attached to the branch. 18 206 CONCLUSIONS DEDUCED BY HALES. The greatest height attained by the mercury was from 21 to 26 inches. On the 21st of April, when the flowering was nearly over, the sap in the middle branch went backwards ; it was absorbed, and so considerably, that the mercury stood 4 inches lower in the open limb than in the other. After a rainy night, on the 24th of April, the sap again rose in the open tube 4 inches. In the first (lowest) branch, the sap went back on the 29th of April, 9 days after the middle one ; the third (highest) branch only began to absorb the sap on the 3d of May, 13 days after the middle one. Conclusions We see from this experiment, as Hales observes, Hales. " That the cause which produces the flow of the sap does not proceed from the root alone, but that it belongs to a force inherent in the stem and branches. For the middle branch followed more rapidly the changes of temperature, of dryness and of moisture, than the two others, and absorbed the sap nine days before one, and thirteen days before the other, both of which, during this time, poured out sap instead of absorbing it. (The cause of the efflux and pressure had, in the older branch, disappeared, and given place to an opposite in- fluence, while it still continued active in the two young- er branches.) " The middle branch was 3 feet 8 inches higher than that next the stem. The height of the mercury in the three tubes was, respectively, 14, 12, and 13 inches. The maximum was 21, 26, and 26 inches. These numbers prove that the greater length of the middle branch had no perceptible influence on the height of the mercury, as compared with that in the other tube." Effectsofcoid In his experiment XXXVIII. , Hales observes, Emotion of " Moisture and warmth made the sap most vigorous. If the beginning or middle of the bleeding season, be- CONCLUSIONS DEDUCED BY HALES. 207 ing very kindly, had made the motion of the sap vig- orous, that vigor would immediately be greatly abated by cold easterly winds.* " If in the morning, while the sap is in a rising state, there was a cold wind with a mixture of sunshine and cloud, when the sun was clouded, the sap would imme- diately visibly subside, at the rate of an inch in a min- ute for several inches, if the sun continued so long clouded ; but as soon as the sunbeams broke out again, the sap would immediately return to its then rising state, just as any liquor in a thermometer rises and falls with the alternacies of heat and cold ; whence it is probable, that the plentiful rise of the sap in the vine in the bleeding season is effected in the same manner." If we consider that the sap in spring, even with a clouded sky, does not cease to rise and flow, for this even goes on during the night, we cannot explain the fall of the sap from the moment that the sun was cov- ered by a cloud by a mere change of temperature in the juice, because the time was too short for the cooling and contraction by cooling (one inch in a minute). Heat determined the more rapid rise, and cold the fall ; but they acted on a cause which lay higher than the * The influence of cold easterly winds, producing what is called blight upon apple-trees, is well known about the eastern extreme of Long Island. The explanation with the views here expounded is simple. The vigorous development of the tree de- pends upon the supply of nutriment from the soil. This requires ascent of the sap. This ascent requires evaporation from the leaves. The evaporation depends upon the capacity of the at- mosphere to take up moisture. The dryer winds from the west will promote the evaporation, while those from off the sea, laden with moisture and protracted through several days, will im- pede it. The shrinking of the leaves, an evidence of deficient nourishment, follows. E. N. H. 208 THE ASCENT OF THE SAP MAY BE CAUSED BY A GAS. root, and which was more sensitive to heat than the liquid itself. Hales says, in his experiment XXXVIII., " In very hot weather many air-bubbles would rise, so as to make a froth an inch deep on the top of the sap in the tube. " I fixed a small air-pump to the top of a long tube, which had twelve feet height of sap in it ; when I pumped, great plenty of bubbles arose, though the sap did not rise, but fell a little, after I had done pumping." In his experiments on the amount of air absorbed by plants, chapter V., he observes, " in the experiments on vines, the very great quantity of air which was contin- ually ascending from the vines, through the sap in the tubes ; which manifestly shows what plenty of it is taken in by vegetables, and is perspired off with the sap through the leaves." When we take these facts into consideration, the opinion appears not untenable, that the incomprehensi- ble force which causes the sap of the vine to flow in spring may be simply referred to a disengagement of gas which takes place in the capillary vessels (filled with liquid, and keeping themselves constantly full), in consequence of a kind of germination ; and it is possi- ble that the height of the column of mercury, or of water, is only a measure of the elasticity of the disen- gaged gas. Let us suppose a strong glass bottle, in the mouth of which a long tube, open at both ends, and reaching to the bottom, is cemented, to be filled with a liquid in which, from any cause, a gas is disengaged (solution of sugar mixed with yeast, for example) ; it is evident that the liquid must rise in the tube from the separation of the gas. When it has risen to 32 feet, the gas will occupy only the half, and at 64 feet, one third, of its volume under the usual atmospheric pressure. In this IS THIS GAS CARBONIC ACID ? 209 case, the height of the liquid in the tube is no measure of a special power residing in the walls of the vessel ; it only shows the tension of the gas. If the walls of the vessel were permeable to the gas, under a certain pressure, no further rise, beyond that point, could occur. If in the apparatus, Fig. 4, we push the tube a through the cork down to the little lead drop ; if we then fill the tube c with water to which some yeast has been added, and a with solution of sugar, and expose the whole to a temperature of from 68 to 75, the liquid rises in Z>, from the gas disengaged in c, very rapidly, so as to overflow. If c be filled with solution of sugar, and a with yeast, the same rise occurs, and lasts till the disengaged gas puts an end to the contact between the membrane and the liquid. It is hardly necessary to point out, that the idea above expressed, as to the cause of the flow and press- ure of the spring sap, is nothing more than an indica- tion of the direction in which experiments must be made. When we know with accuracy the volume of the liquid which flows out of a vine at the time of flowering, and the quantity of gas which is developed Gas is proba- at the same time, we shall, I trust, find ourselves a step nearer to the explanation of this phenomenon. Ac- cording to the experiments of Geiger and Proust, the sap of the vine is rich in carbonic acid ; and it is possi- ble that the gas which is disengaged may be no other than carbonic acid gas. 18 ' APPENDIX. A. - (p. 22.) THE suggestion in the editor's paper upon Glycocoll, that organized bodies are composed of lesser, already distinctly formed groups, has met with .strong support in an elaborate investigation by Dr. Guckelberger,* As- sistant in the Giessen Laboratory. M. Schlieper had studied with care the products of decomposition of gelatine by chromic acid. Dr. Guckelberger treated caseine, albumen, and fibrine both by manganese and chromic acid, and found that, except in relative quanti- ties, the products of decomposition were the same or greatly alike in all. Now, as Dr. G. has aptly remarked, there being no essential difference in the nature of the products yield- ed by the oxidation with manganese from those yielded by oxidation with chromic acid, notwithstanding these agents hold oxygen with unequal degrees of affinity, it follows that it is the presence of oxygen, not its quan- tity, that determines the character of the bodies pro- duced. The oxygen serves to separate bodies, already formed, from each other's embrace. It removes a ce- ment that held the members of a structure together. The following bodies were obtained by Dr. Guckel- * Liebig's Annalen, LXIV. p. 39. 212 APPENDIX. berger in the distillate from caseine, black oxide of manganese, and sulphuric acid : 1. Aldehyde of acetic acid, . . . C 5 H 3 O, HO 2. Aldehyde of metacetonic acid, . Ce HS O, HO 3. Aldehyde of butyric acid, . . . C 5 H 3 O, HO 4. Oil of bitter almonds, . . CM H 5 O 2 , H 5. Formic acid, . . . C 2 H O 3 , HO 6. Acetic acid, . C 4 H 3 O 3 , HO 7. Metacetonic acid, . . . . Ce Hs O 3 , HO 8. Butyric acid, . . . . C 8 H 7 O 3 , HO 9. Valerianic acid, . . . . Ci Hg O 3 , HO 10. Caproic acid, Ci 2 Hu O 3 , HO 11. Benzoic acid, . . . . CM Hg O 3 , HO The following bodies were obtained on decomposing caseine with chromate of potash and sulphuric acid : 1. Aldehyde of metacetonic acid, . . Ce H 5 O, HO 2. Oil of bitter almonds (in small quantity), CM HS O 2 , H 3. Formic acid (in small quantity), . . Cg H O 3 , HO 4. Acetic acid, . . . . C 4 H 3 O 3 , HO 5. Butyric acid, . . . . C 8 H 7 O 3 , HO 6 Valerianic acid, . . . Cio Hg O 3 , HO .7. Benzoic acid (with traces of caproic acid). 8. Benzoic acid, . . . . C H H 5 O 3 , HO 9. Prussic acid, . . . . C 2 N H, 10. Valeronitrile, . . . . C 10 H 9 N, 11. A heavy oil with the odor of cinnamon. 12. Metacetonic acid, . . . . C 6 H 5 Os, HO EBEN N. HORSFORD. APPENDIX. 213 B. ON THE NATURE AND PREVENTION OF THE POTATO DISEASE. AFTER the preceding pages were in print, I received from Baron Liebig a copy of the Journal of the Agri- cultural Association of the Grand Duchy of Hesse (Darmstadt), No. 7, dated 15th February, 1848, contain- ing the account of a method proposed by Dr. Klotzsch (Keeper of the Royal Herbarium, Berlin, and a distin- guished botanist and vegetable physiologist), for pre- venting the ravages of the potato disease. The pro- posal of Dr. Klotzsch, and his views as to the nature of the disease, are such as materially to strengthen the opinions expressed on this subject by Baron Liebig (see pj>. 198, seq.). As a knowledge of the method suggested by Dr. Klotzsch is likely to be interesting to many of the readers of this work, I have thought it right to give it in an Appendix. WILLIAM GREGORY. METHOD PROPOSED BY DR. KLOTZSCH FOR THE PROTEC- TION OF THE POTATO PLANT AGAINST DISEASES. " The potato, which is an annual plant, represents, in the tubers developed from the stem, the perennial part of a plant. For while the duration of its development is analogous to that of annuals, its actions coincide ex- actly with those of dicotyledonous shrubs and trees. " The potato plant differs from all those plants which are cultivated for economical purposes in Europe, and can only be compared to those orchidious plants which yield salep, and which are not yet cultivated among us. 214 APPENDIX. " The tubers, both of the potato and of the salep plants, are nutricious, and agree in this, that in the cells of the tubers, grains of starch, with more or less azo- tized mucilage, are collected, while the cell walls pos- sess the remarkable property of swelling up into a jelly, and thus becoming easily digestible when boiled with water. " But while the tuber of salep contains only one bud, or germ, the potato usually develops several, even many, germs. " The potato plant, like all annuals, exerts its chief efforts in developing flowers and fruit. Like all annu- als, too, it has the power of shortening this period of de- velopment, when the power of the roots is limited ; as also of lengthening it when the extent and power of the roots are increased. " We observe in nature, that plants with feebly de- veloped roots often have a weak, sickly aspect, but yet come to maturity in flower and fruit sooner than strong- er individuals, well furnished with roots. " In perennial plants, we observe a second effort, which is directed towards preparing and storing all nu- tritious matter, for the consumption of the plant. The preparation of this nutriment is effected by the physio- logical action of the leaves, under the influence of the roots. The stronger and larger the former are, the more is this preparation of food delayed. " The nutritious matters are stored in the colored stratum of the bark in shrubs and trees, and in the tu- bers in the potato and salep plants. Not only, however, the nutrient matters, but also the cells, owe their origin to the physiological action of the leaves. " On considering these things, it follows that the pota- to plant requires more care than is usually devoted to it. Hitherto the whole cultivation has consisted in clearing APPENDIX. 215 off weeds, and hoeing up the earth round the stems. Both of these measures are indeed necessary, but they are not alone sufficient ; for the plant is cultivated, not on account of its fruit, but for the sake of its tubers, and the treatment should be modified accordingly. " The chief points to be attended to, with a view to the attainment of the object, namely, the increase of tu- bers, are, "1. To increase the power in the roots ; and, "2. To check the transformation which occurs in the leaf. " We obtain both ends simultaneously, if, in the 5th, 6th, and 7th week after setting the tubers, and in the 4th and 5th week after planting out germs furnished with roots, or at a time when the plants reach the height of six to nine inches above the soil, we pinch off the extreme points of the branches or twigs to the extent of half an inch downwards,* and repeat this on every branch or twig in the 10th and llth week, no matter at what time of day. " The consequence of this check to the develop- ment of the stem and branches is a stimulus to the nu- trient matters in the plant in the direction of the in- crease both of roots and of the multiplication of the branches of the stem above ground, which not only fa- vors the power of the root, but also strengthens the leaves and stalks to such a degree, that the matters pre- pared by the physiological action of these parts are increased and applied to the formation of tubers, while at the same time the direct action of the sun's rays on the soil is prevented by the thick foliage, and thus the * Any one would be bitterly disappointed, who, on the prin- ciple that " there cannot be too much of a good thing," should take off more than is here recommended, in order to use it as fodder 216 APPENDIX. drying up of the soil and its injurious consequences are avoided. " The checking of the transformation in the leaf is equivalent to the interruption of the natural change of the leaves into calyces, corollse, stamens, and pistils, which is effected at the expense of the nutrient matters collected in the plant ; and these, when this modifica- tion of the leaves is arrested, are turned to account in the formation of tubers. " Led by these views, I made, in 1846, experiments on single potato plants, carefully marked, by pinching off the ends of the branches. They were so readily distinguished in their subsequent growth from the plants beside them, by more numerous branches, larger and darker foliage, that in truth no marking was necessary. " The produce from these plants of tubers was abun- dant, and the tubers were perfectly healthy ; while the plants next them which had not been so treated, gave uniformly a less produce, at the same time the tubers were rough on the surface, and in many instances at- tacked with the prevailing disease. This experiment was incomplete, and did not give a positive result, but it was yet encouraging for me. " In the middle of April, 1847, an experiment was made on a low-lying field with the round white pota- toes generally cultivated here, a variety which had not suffered much from the disease which first appeared here in 1845. The potatoes were planted in the usual way, by an experienced farm servant. " After weeding them in the end of May, I renewed my experiment by pinching off the points of the branch- es of every second row, and repeated this in the end of June. The result surpassed all expectations. The stalks of the plants not treated on my plan were long, straggling, and sparingly furnished with leaves, the leaves themselves small and pale green. APPENDIX. 217 " In the next field, potatoes of the same variety were planted on the same day, and left to nature. They ap- peared in the first six weeks healthy, even strong, but gradually acquired a poor aspect as the time of flower- ing and fruit approached, and finally exhibited precisely the same appearances as the rows not treated by pinch- ing off the extremities in the field in which my experi- ments were made. " The harvest began in the surrounding fields in the middle of August, and was very middling. The tubers were throughout smaller than usual, very scabby, and, within these fields, to a small extent, attacked by the wet rot. " In the end of August, the difference between the rows treated by me and those not treated became so striking, that it astonished all the work-people in the neighbourhood, who were never tired of inquiring the cause. The stalks of the rows left to themselves were all now partly dried, partly dead. On the contrary, the rows treated as above were luxuriant and in full vigor, the plants bushy, the foliage thick, the leaves large and dark green, so that most people supposed they had been later planted. " But the difference in the tubers was also very de- cided. The tubers of the plants in the rows treated on my plan were not indeed larger, but vastly more nu- merous, and they were neither scabby nor affected with any disease whatever. A few had pushed (which was to be ascribed to a late rain), and were apparently in- completely developed, while scab and wet rot attacked more and more the tubers of the other plants, which also fell off on the slightest handling. " Although I am far from believing that I am able to explain the nature of the potato disease which has visited us of late years, yet I feel certain that I have discov- 19 218 APPENDIX. ered a means of strengthening the potato plant to such a degree as to enable it to resist the influences which determine such diseases. " Should any one be deterred from continuing the cultivation of potatoes on account of the manipulation here recommended, which may be performed by women and even by children, I would remind him that the same field planted with potatoes is capable of supplying food to twice as many persons as when employed to grow wheat." (From the Annals of Agriculture in Prus- sia, edited by the College of Rural Economy.) Dr. Klotzsch presented to the king of Prussia a me- morial, offering to give to the world his method of pre- venting disease in potatoes, provided he were assured of a remuneration of 2,000 dollars (about $ 1,400), if, after three years' experience, it should be found efficacious. The king handed the memorial to the Minister of the Interior, who requested the College of Rural Economy to discuss the matter with Dr. Klotzsch. The president of the College undertook the arrange- ment, and, after Dr. Klotzsch had explained to him pri- vately his method, reported most favorably of it to the College, which unanimously recommended that the very moderate remuneration asked for by Dr. Klotzsch should be secured to him on the following conditions, which were accepted by him. 1. That the College of Rural Economy should be the judges of the efficacy of the proposed method. 2. That their decision should be given, at latest, with- in three years, provided the potato disease, against which the plants are to be protected, should appear during that period. The Minister of the Interior approved of the recom- APPENDIX. 219 mendation, and authorized the College to conclude an agreement with Dr. Klotzsch. The agreement has been concluded, and now the method is published, that it may be tried and tested as widely as possible by comparative experiments, similar to those made by Dr. Klotzsch himself. The cost of it is stated not to exceed 35 cents per acre in Germany. It is very desirable that this method should be tried in the British islands, and as the season for trying it now approaches, I have here given Dr. Klotzsch's ac- count entire. WILLIAM GREGORY. THE END. THIS BOOK IS DUE ON THE LAST DATE STAMPED BELOW AN INITIAL FINE OF 25 CENTS WILL BE ASSESSED FOR FAILURE TO RETURN THIS BOOK ON THE DATE DUE. THE PENALTY WILL INCREASE TO 50 CENTS ON THE FOURTH DAY AND TO $1.00 ON THE SEVENTH DAY OVERDUE. Book Slip-20m-3,'60(A9205s4)458 Researches chemistry of CaU Number: 1848 : b TX53 L5 207803 I Ull ill! iilll III.! Hliillil