/^^^l-^/^V^^ /to*~. HOWARC^TOW^SF/VD, !\I D. CHEMICAL AND PHYSIOLOGICAL BALANCE OF ORGANIC NATURE. THE CHEMICAL AND PHYSIOLOGICAL BALANCE OF ORGANIC NATURE: AN ESSAY, BY M. J. MMAS AND M. J. B. JOUS SIN GAUL T, MEMBERS OF THE INSTITUTE OF FRANCE. EDITED BY D. P. GARDNER, M. D., Lecturer on Agricultural Chemistry, &c. FROM THE THIRD EDITION, WITH NEW DOCUMENTS. NEW YORK: PUBLISHED BY SAXTON & MILES, 205 Broadway. BOSTON: SAXTON, PEIRCE & CO. im. Entered according to the Act of Congress, in the year 1844, by SAXTON & MILES, in the Clerk's office of the District Court for the Southern District of New York. 0 u ■* . nf J J 1) If " 44 8. W. BENEDICT & CO., PRINT., 16 Spruce Street CONTENTS. PAGE Preface....................................... ix Programme of the Discourse...................... xiii Introduction................................... 15 Composition of Water........................... 27 ---- Carbonic Acid.................... 28 ---- Ammonia........................ 29 ---- Atmospherical Air................. 30 Phenomena of Vegetable Life :— Plants fix Carbon........................... 37 ---- Hydrogen......................... 42 ---- Azote............................ 43 Source of the Ashes of Plants................. 47 Heat of Plants—Germination, Fructification...... 48 Phenomena of Animal Life :— Animals consume or burn Carbon............. 51 ---- Hydrogen........... 52 Exhalation of Azote by Animals.............. 52 Purpose of the Urea Excreted................ 53 Digestion.................................. 57 Theory of Respiration and Animal Heat........ 58 Recapitulation................................. 61 VI11 CONTENTS. PAGE Documents................................... 65 i. Composition of Carbonic Acid............. 65 n. --- Water................... 66 in. --- Oxide of Ammonia......... 68 iv. --- the Air.................. 69 v. --- the principal Ternary Com- pounds of Vegetables...... 71 vi. --- the Neutral Quaternary Or- ganic Substances......... 73 vii. Principal Chemical Effects of Germination.. 82 viii. Principal Chemical Phenomena of Vegetation 92 ix. Respiration of Man..................... 106 x. Exhalation of Azote by Animals.......... 120 xi. Excretion of Urea...................... 122 xii. Heat of Animals and of Vegetables........ 123 xiii. Of the Source of the Mineral Substances which are met with in Organized Beings.. 126 xrv. Theory of Digestion.................... 127 Formation of Fatty Substances.................... 132 Historical Data:— Respiration and Animal Heat................ 136 Use of the Balance—Fixation of Carbon and Hy- drogen by Plants......................... 141 Source of the Azote of Plants................. 148 " Carbon of Plants .............. 155 General Views in regard to the part played by Plants in the Economy of Nature............ 161 Works and papers referred to..................... 169 Appendix .................................... 172 PREFACE. There have been in Chemistry and all experi- mental sciences, epochs in which the accumulating facts of many years have led to great discoveries. Such were the periods of the separation of the at- mospheric gasses, the synthesis of water, the estab- lishment of a chemical nomenclature, the analysis of alkaline and earthy bodies, the process of organic analysis by Liebig. These events are important to the progress of science by interesting large numbers of persons not devoted to its cultivation. For a time scientific facts intrude even into the discussions of fashionable assemblies, because of their novelty ; but hitherto they have made little permanent impression. A new epoch has arrived in Chemistry. The functions of organized bodies, the laws of life, are the subjects of investigation. It is destined to be far more brilliant and important than any which has gone before. It does not promise to satisfy the curiosity of the people only, but to unfold truths of the most serious consequence to our species. Medicine, Agri- culture, Political Economy, will per farce be illus- trated by Chemistry. Hitherto the mass of mankind X PREFACE. have been amused by remarkable discoveries ; we have now reached a period when they are to be con- trolled by them. Liebig's Animal and Vegetable Chemistry have awakened the attention of many ; they are the earliest of a series of publications for which the labors of Dumas and Boussingault have furnished the most valuable materials. In this little work those philoso- ', phers have expressed their own doctrines, prefatory to a more detailed practical treatise. In the words of M. Dumas, this essay " presents a variety of new views, calculated to supply general physiology, medicine, and agriculture, with grounds upon which the study of the chemical phenomena | that take place in organized beings may be advan- tageously pursued. " We feel intimately persuaded that the conside- rations embraced in this Essay may henceforth be made to bear upon many of the most important ques- tions of public economy.—Not that we have given such development to our principles as makes them always obviously applicable to matters of detail,__ time alone wall admit our doing this ; but we appre- hend that our views, generally speaking, are so stated, as to show conclusions interesting to the le- gislator and public economist in connexion with agri- culture in general, and in particular with the growth of corn, and of sugar, the feeding of cattle, and above all, with that question,—of such vital importance__ preface. x» the maintenance of the laboring classes of man- kind." The opinion of scientific Europe has been freely canvassed and expressed in respect to the views of the authors. They were first pronounced by M. Dumas in the Ecole de Medecine, where their value was at once recognized. The leading journals printed them with applause, and although but four years have elapsed, the essay has passed to a third edition, and been translated from the French into English, Ger- man, Spanish and Italian. To attempt to exalt the reputation of Dumas and Boussingault is supererogatory. The greatest lib- erty taken with the work is the omission of their pre- face, part of which is incorporated herein. All addi- tions bear the editor's initials. D. P. Gardner. New York, May 15th, 1844. PROGRAMME OF THE DISCOURSE. AN ANIMAL is An Apparatus of Combustion ; Possesses the faculty of Loco- motion ; Burns Carbon, Hydrogen, Ammonium; Exhales Carbonic Acid, Water, Oxyde of Ammo- nium, Azote; Consumes Oxygen, Neutral Azotised matters, Fatty matters, Amylaceous mat- ters, sugars, gums; Produces Heat, Electricity; Restores its elements to the air or to the earth; Transforms organized matters into mineral matters. 2 A VEGETABLE is An Afparatus of Reduction ; Is fixed; Reduces Carbon, Hydrogen, Ammonium ; Fixes Carbonic Acid, Water, Oxide of Ammo- nium, Azote; Produces Oxygen, Neutral Azotised matters, Fatty matters, Amylaceous mat- ters, sugars, gums ; Absorbs Heat, Abstracts Electricity; Derives its elements from the air or from the earth; Transforms mineral matters into organic matters. THE CHEMICAL AND PHYSIOLOGICAL BALANCE OF ORGANIC NATURE: A LECTURE DELIVERED BY M. DUMAS, On concluding his Course, at the Ecole de Medicine. Gentlemen, Among the phenomena of life, whose deep- est mysteries you are called upon to fathom, there are some which obviously connect themselves with the forces that material nature herself brings into play, others which emanate from a source higher and less accessible to even the boldest flights of thought. It is not among my duties with you to scan with curious eyes that part of your studies which has reference to the due or jarring exercise of the in- stincts of life. Still less have I had occasion to speak of those noble faculties by which the human mind, mastering all that surrounds it, breaking 16 THE EALANCE down all barriers, bending all the forces of nature to its wants, has, by degrees, made empire of the earth, of the ocean, of the whole globe which we inhabit,—a vast domain, in sooth, yet one which our aspirations, our presentiments, perchance, still lead us often to regard but as a prison. To others, more fortunate, the pleasing task of initiating you in studies so grave as these, of un- folding to you the noble thoughts to which such subjects lead ; my task, more humble, is limited to the field that embraces the physical phenomena of life; and even among these there are many for which we have been able to find no place in our Course. We have, in fact, had our attention mainly di- rected to the part which matter plays in the pro- duction and growth of organized beings, in the accomplishment of the phenomena of their daily existence, in the changes which their bodies un- dergo after their death ; and we have found these subjects amply sufficient to engage us through the present year. I. Vegetables, animals, man, contain matter in their composition. Whence comes it 1 Wliat part does it play in their tissues and in the fluids which bathe them 1 What becomes of it when death breaks OF ORGANIC NATURE. 17 the chain by which its various parts and forms were so closely conjoined 1 Such are the questions which we approached with so much diffidence at first, inasmuch as to answer them might have been beyond the powers of modern chemistry; but, by and by, with greater confidence, when we felt, by the silent and secret accord of our minds, that our footing was sure, and as we saw that the wished-for goal was gradually approached in spite of every obstacle. If, from this labor, at which you have heen spectators,— in which, I should rather say, you have lent your aid,—if from this scientific effort some general views have arisen, some simple and comprehensive formulas have appeared, I feel that I ought to make myself the historian of these :—but allow me the pleasure of adding that they also belong to you, that they belong to our school, the spirit of which has, of late, been unfolding itself upon this new ground. It is the zeal, indeed, with which you have followed me in this career that,has given me the strength to pursue it; it is the lively interest you have taken that has sustained me, your curi- osity which has awakened mine, your confidence which has made me see,—which assures me at this moment, that we are in the path of truth. These words will bring to your minds with what amazement we discovered together, that of all the 2* 18 THE BALANCE elements of modern chemistry, organic nature made use of but three or four ; that of those vegetable and animal substances which are now multiplied almost to infinity, general physiology requires no more than some ten or twelve species ; and that all the phenomena of life, so complex in appear- ance, may be referred in their essence to a single general formula, so simple, that in a few words everything seems stated, everything having been recalled to mind, every thing foreseen. Have we not, in fact, found, by a multitude of results, that an animal, in a chemical point of view, constitutes a true apparatus of combustion, by which carbonaceous matters, burnt incessantly, are returned to the atmosphere in the shape of carbonic acid ; in which hydrogen, burnt incessantly, is re- turned as water; whence, in fine, free azote is ceaselessly exhaled in the breath, and, in the state of oxide of ammonium, is thrown off in the urine 1 From the animal kingdom, therefore, as a whole, carbonic acid, watery vapor, and azote or oxide of ammonium, are continually escaping,—simple substances, and few in number, the formation of which is intimately connected with the history of the atmosphere itself. Have we not, on the other hand, found that ve- getables, in their natural and healthy state, decom- pose carbonic acid incessantly, fixing the carbon OF ORGANIC NATURE. 19 and setting free the oxygen; that they decompose water, seizing on its hydrogen, and disengaging its oxygen as before; lastly, that they either ab- stract azote directly from the air, or take it indi- rectly from oxide of ammonium, or nitric acid; thus acting, in every particular, inversely or in op- position to animals ? If the animal kingdom con- stitute an immense apparatus of combustion, the vegetable kingdom, in its turn, constitutes an im- mense apparatus of reduction, where carbonic acid decompounded leaves its carbon, water its hydro- gen, and oxide of ammonium and nitric acid their ammonium or their azote. If animals incessantly produce carbonic acid, water, azote, and oxide of ammonium, vegetables consequently consume, without cessation, oxide of ammonium, azote, water, and carbonic acid. What the one gives to the atmosphere, that the other takes from it; so that, surveying these facts from the loftiest point of view, and in connection with the physics of the globe, it would be imperative on us to say that, in so far as their truly organic ele- ments are concerned, plants and animals are the offspring of the air ; that they are but condensed or consolidated air; and that, to form a true and accurate idea of the constitution of the atmosphere at the epochs which preceded the birth of organized beings, it would be necessary to restore to it, by 20 THE BALANCE calculation, the whole of the carbonic acid and azote, the elements of which were appropriated by- vegetables and animals when they appeared. Vegetables and animals, therefore, come from the atmosphere, and return to it again; they are true dependants of the air. Vegetables, then, assume from the atmosphere the elements which animals exhale into it; viz. carbon, hydrogen, and azote, or rather carbonic acid, water, and ammonia. But how do animals procure the elements which they give to the atmosphere ? Let us inquire par- ticularly into this point. Now it is impossible to contemplate, without admiration, the sublime sim- plicity of the laws of nature here, as everywhere ! Animals always derive their elements primarily from vegetables. We have found, in fact, by results beyond the reach of question, that animals do not create any of the truly organic substances, but that they con- sume or destroy them ; that vegetables, on the contrary, habitually create these substances, and that they destroy but few, and this only for par- ticular and determinate ends. It is in the vegetable kingdom, therefore, that the great elaborately of organic life is found; it is there that both vegetable and animal substances OF ORGANIC NATURE 21 are compounded : and they are all alike formed at the cost of the atmosphere. From vegetables these substances pass ready- formed into the bodies of herbivorous animals, which destroy one portion of them, and store up another in their tissues. From herbivorous animals they pass ready- formed into the bodies of carnivorous animals, which destroy or lay them up, according to their wants. Finally, during the life of these animals, or after their death, the organic substances in question re- turn to the atmosphere from whence they origi- nally came, in proportion as they are destroyed. Thus is the mysterious circle of organic life upon the surface of the globe completed and maintain- ed ! The air contains or engenders the oxidized substances required,—carbonic acid, water, nitric acid, and ammonia. Vegetables, true-reducing apparatus, seize upon the radicals of these, carbon, hydrogen, azote, ammonium ; and with them, they fashion all the variety of organic or organizable matters which they supply to animals. Animals, again, true apparatus of combustion, reproduce from them carbonic acid, water, oxide of ammo- nium, and azotic or nitric acid, which return to the air to reproduce the same phenomena to the end of time. 22 THE BALANCE And if, to this picture, already so striking by its simplicity and grandeur, we add the indubitable part performed by the solar light, which is alone possessed of power to bring into play this immense, this unparalleled apparatus, constituted by the ve- getable kingdom, in which the oxidized products of the atmosphere are subjected to reduction, it is impossible not to be struck with the import of these words of Lavoisier: " Organization, sensa- tion, voluntary motion, life, only exist on the sur- face of the earth and in places exposed to light. It might be said, indeed, that the fable of Prome- theus was the expression of a philosophical truth, which had not escaped the penetration of the an- cients. Without light, nature were without life and without soul: a beneficent God, in shedding light over creation, strewed the surface of the earth with organization, with sensation, and with thought!" These words are as true as they are eloquent. If sensation and thought, if the noblest faculties of the soul and the understanding require a material vesture for their manifestation, vegetables are the laborers charged with the task of building it up, and from elements which they derive from the air, and elaborate under the influence of the light which the sun, its inexhaustible fountain, pours in ceaseless floods upon the earth. OF ORGANIC NATURE. 23 And as if all in these grand phenomena were destined to be associated with causes which should appear the most remote, we may here observe upon the sources whence the oxide of ammonium and azotic acid, from which vegetables derive a por- tion of their food, are themselves derived. They are, in fact, produced upon the grand scale by the action of those magnificent electric sparks that dart from the storm-cloud, and, furrowing vast fields of air, engender in their course the nitrate of am- monia, which analysis discovers in the thunder- shower. As it is from the mouths of volcanoes, then, whose convulsions so often make the crust of our globe to tremble, that the principal food of plants, carbonic acid, is incessantly poured out; so is it from the atmosphere on fire with lightnings, from the bosom of the tempest, that the second and scarcely less indispensable aliment of plants, ni- trate of ammonia, is showered down for their be- hoof. Might it not be said, that we have here a re- membrancer of that chaos mentioned in the Bible, of those periods of tumults and disorders tohich pre- ceded the appearance of order and organization upon earth ? For, scarcely are carbonic acid and nitrate of ammonia formed, than a calmer, though not less 24 THE BALANCE energetic force begins to act upon them for new purposes: this force is light. By the agency of light, carbonic acid yields up its carbon, water its hydrogen, nitrate of ammonia its nitrogen. These elements combine, organic matters are formed, and the earth is clothed with verdure. It is, in fact, from absorbing incessantly a true force, the light and heat of the sun, that vegeta- bles perform their functions, and produce the vast quantities of organized or organic matter which are the destined food of the animal creation. And then, if we add that on their side animals engender heat and elicit force in consuming that which vegetables have produced and slowly accu- mulated, would it not seem that the ultimate in- tent of all these phenomena, that their most gene- ral or comprehensive formula was laid open to our view 1 The atmosphere presents itself to us as includ- ing the primary material of all organization. Vol- canoes and thunder-storms meet us as the labora- tories in which are compounded the carbonic acid and nitrate of ammonia which life requires for its manifestation and extension. Light arrives, and with the concurrence of car- bonic acid and nitrate of ammonia, the vegetable world, the grand producer of organic matter, is de- veloped. Plants farther absorb the chemical force OF ORGANIC NATURE. 25 which reaches them from the sun, and enables them to decompose carbonic acid, water and am- monia ; plants are embodiments of a reducing power, of greater virtue than any other that is known, for no other will decompose carbonic acid in the cold. Then come animals, consumers of matter, and producers of heat and of force, true instruments of combustion. It is in them, unquestionably, that organized matter acquires what may be called its highest expression. But it is not without detriment to itself that it becomes the instrument of sensa- tion and of thought. In this new capacity orga- nized matter is burnt; and in giving out the heat, or electricity, which constitutes and is a measure of our force, it is destroyed and returned to the atmo- sphere, from whence it had originally come. The atmosphere, therefore, is the mysterious link that connects the animal with the vegetable, the vegetable with the animal kingdom. Vegetables absorb caloric, and store up the matter which they have had the power to fashion ; Animals, again, through which, it may be said, that organic matter merely passes, burn or con- sume it, to produce by its means the heat and va- rious forces which their motions turn to profit. Allow me here, borrowing a simile from modern science, of grandeur somewhat commensurate with 3 26 THE BALANCE these grand phenomena, to liken the vegetable world of the present age, the true store-house whence animal life is fed, to that other magazine of carbon which we possess in our primeval beds of coal, and which, burnt under the genius of Pa- pin and of Watt, produces carbonic acid, water, heat, motion,—we might almost add, life and intel- ligence. In our eyes, therefore, the vegetable world con- stitutes an immense magazine of combustible mat- ter, destined to be consumed by the animal world, and in which this last finds the source of the heat and locomotive powers which it turns to account. A common link between the two organic king- doms, then—the atmosphere ; four elements in ve- getables and in animals—carbon, hydrogen, azote, and oxygen ; a very limited number of forms un- der which vegetables lay these up, under which animals consume them ; a few laws of great sim- plicity, which their enchainment simplifies still more : such is the picture of organic chemistry in the abstract, which results from our studies of the present session. You, doubtless, felt as I did myself, that, before finally separating, it would be well for us to fall back upon ourselves, as it were, to make sure of our data, and to contrast and review our opinions, in which are involved the explanation and deve- OF ORGANIC NATURE. 27 lopment of the grand principles which we have an- nounced ; finally, that it would be advantageous to you in your future studies, to have in writing, and in precise terms, the expression of views which have been engendered in part under the sti- mulus of your regards, and therefore presented with the hesitation which so frequently accompa- nies the first cast of our thoughts. II. Inasmuch as all the phenomena of life are car- ried on upon substances having for their basis car- bon, hydrogen, nitrogen, and oxygen; inasmuch as these substances pass from the animal to the vege- table kingdom, through intermediate forms—car- bonic acid, water, and oxide of ammonium; since, in fine, the air is the source whence the vegetable world is nourished, is the reservoir within whose bosom the animal world is annihilated, we are naturally led to study these different bodies from the particular point of view of general physiology. Composition of Water (1).—Water is incessant- ly formed and decomposed in the bodies of ani- mals and vegetables. With a view to the due appreciation of what is to follow, let us inquire into its composition. Direct experiments,—the com- bustion of hydrogen in oxygen gas,—in which I have produced more than a quart of artificial wa- 28 THE BALANCE ter, render it extremely probable that water £is composed by weight, of 1 part Hydrogen, and 8 parts Oxygen, and that these simple and round numbers express the prime relations in which these two elements combine to constitute water. As substances are always represented in the eyes of the chemist by atoms or molecules, as he always seeks to connect in thought, with every substance, the weight of its atom, the simplicity of the rela- tion just stated is not without importance. Each atom of water, in fact, being a compound of one atom of hydrogen and one atom of oxygen, we arrive at those simple numbers, which are not rea- dily forgotten. An atom of hydrogen weighs 1, an atom of oxygen weighs 8, and an atom, or molecule of water, weighs 9. Composition of Carbonic Add (2).—Carbonic acid is produced incessantly by animals, and de- composed incessantly by plants; its composition, therefore, merits especial attention on our part. Now carbonic acid, like water, is represented by the most simple numbers. Experiments in which the diamond was burnt directly, and converted into carbonic acid, have satisfied me that this acid is formed by the combi- OF ORGANIC NATURE. 29 nation of 6 parts, by weight, of carbon, with 16 parts, by weight, of oxygen.* We are, therefore, led to represent carbonic acid as formed of 1 atom of carbon weighing 6, and two atoms of oxygen weighing 16, which toge- ther constitute 1 atom of carbc-nic acid weighing 22. Composition of Ammonia (3).—Finally, am- monia would appear, in its turn, to be formed, in round numbers, of 3 parts of hydrogen and 14 of azote, which may be represented by 3 atoms of hydrogen weighing 3, and 1 atom of azote weigh- ing 14. Thus, as if to show her infinite resources, Nature does not bring into play, in connection with orga- nization, more than a very small number of ele- ments, combined in the simplest relations. The whole atomic system of the physiologist, in fact, revolves upon these four numbers, 1, 6, 7, 8 : 1 is the atom of hydrogen, 6 is that of carbon, 7, or twice 7=14, is that of azote, and 8 is that of oxygen. Let him always attach these numbers to these names; because to the chemist no such things as abstract hydrogen, carbon, azote, or oxygen, exist. They are always true entities which he has in * .See Appendix A. 3* 30 THE BALANCE view; it is of their atoms that he invariably speaks, and for him the word hydrogen signifies an atom which weighs 1, the word carbon an atom which weighs 6, and the word oxygen an atom which weighs 8. Composition of the Air (4).—Has the atmo- sphere which plays so important a part in organic nature, as simple a constitution as water, carbonic acid, and ammonia 1 Such is the question which M. Boussingault and I have lately studied atten- tively. And we have found, in conformity with the opinions of the majority of chemists, and in op- position to the views of Dr. Prout, to whom che- mistry is indebted for so many ingenious inquiries, that air is a mixture, a true mixture. The air of the atmosphere contains, by weight, 2300 of oxygen to 7700 of azote; by volume, 208 of the former to 792 of the latter. The air contains, in addition, from x^Voffths to ioo6ootbs> by volume, of carbonic acid, whether it be taken in the midst of a great city such as Paris, or in the country. (5) In general it con- tains about Tolooths of carbonic acid. The air, moreover, contains an almost inappre- ciable quantity of the carburetted hydrogen gas, which is incessantly eyolved by stagnant waters and marshes. (6)* _ We do not here speak of the watery vapor, the * See Appendix. B. OF ORGANIC NATURE. 31 quantity of which varies so much at different times, nor yet of the oxide of ammonium and nitric acid, which can only exist momentarily in the atmo- sphere, by reason of their great solubility in water. The air of the atmosphere, therefore, is a mix- ture of oxygen, nitrogen or azote, carbonic acid, and carburetted hydrogen, or marsh-gas. The quantity of carbonic acid in the atmosphere varies, and that even considerably, inasmuch as the difference extends from ro^oo^18 to xo^ooths. Might not this fact be cited as a proof that plants abstract carbonic acid from the air, whilst animals exhale it ? is it not an assurance that the equi- librium in the elements of the air is rightly ascribed to the inverse action of animals and of vegetables upon it ? It is long, indeed, since it was observed, that animals rob the air of its oxygen,* and exhale into it carbonic acid ; and that plants, in their turn, de- compose this carbonic acid, fixing its carbon, and restoring its oxygen to the air. As animals go on breathing incessantly, and as plants only respire under the influence of the solar light; as in winter, the earth is stripped and naked, whilst in summer it is clothed with ver- dure ; it was believed that the air ought to bear witness in its constitution to these varying states or influences. The carbonic acid, it wras imagined * See Append"1" 32 THE BALANCE must increase in the night and diminish in the day ; the oxygen, on the contrary, diminish in the night and increase in the day. The carbonic acid and the oxygen, it was also conceived, must follow the course of the seasons, augmenting inversely in one, falling off inversely in the other. (7) All this is true, undoubtedly, and perfectly sen- sible in regard to small portions of air confined under a bell-glass; but in the mass of the atmo- sphere all local and temporary differences are lost and confounded. A long succession of ages would be requisite to bring into play and render manifest any preponderance in either of the two realms of nature, with reference to the composition of the atmosphere. We are, therefore, far—very far from experiencing those daily or annual variations which philosophers and the vulgar were at one time alike disposed to regard as equally easy to observe and to foresee. (8) With regard to the oxygen, calculation shows that, even in exaggerating all the data, not less than 800,000 years must elapse before the animals living on the surface of the earth could consume it entirely. If it be supposed, therefore, that an accurate analysis of the air was made in the year 1800; and that through the whole of the succeeding cen- OF ORGANIC NATURE. 33 tury, plants had ceased from their functions over the entire surface of the earth, all the animals, nevertheless, being conceived to go on, living and breathing as usual, an analysis undertaken in 1900 would not show the oxygen of the air diminished to any greater extent than ^oVo^ Part °^ ^s weight, a quantity which is altogether inappreciable to the most delicate means of investigation we pos- sess at the present day, and which, very certainly, would have no influence on the life of animals. Nevertheless we do not deceive ourselves as to the fact; the oxygen of the air is consumed by ani- mals, which convert it into water and carbonic acid; and it is restored by vegetables, which de- compose these two substances. But nature has so arranged matters that the mag- azine of the atmosphere, in reference to its consump- tion by animals, is such, that the necessity for the intervention of vegetables for its purification could only become apparent after the lapse of centuries. The atmosphere which surrounds us weighs as much as 581,000 cubes of copper, one kilometre in the side ; its oxygen alone weighs as much as 134,- 000 of these cubes. Now, supposing the earth to be peopled by 1,000,000,000 of men, and its ani- mal denizens to be equivalent to 3,000,000,000 of men, it may be shown that these together do not con- sume a weight of oxygen equal to 15 or 16 cubic 34 THE BALANCE kilometres of copper in the course of a year, whilst the air, as we have seen, contains 134,000 of such kilometres. It would require no less a period than 10,000 years before all the men on the face of the globe could produce any effect that should be sensible to Volta's eudiometer, even supposing vegetable life to be extinct during the whole of this time. With regard to the question of permanence in the composition of the atmosphere, therefore, we may say, with a perfect assurance of accuracy, that the proportion of oxygen which it contains is secur- ed for a long succession of ages, even supposing the influence of the vegetable world to be nil; and that plants, nevertheless, go on incessantly restoring to it oxygen in quantity at least equal, and perhaps even superior, to that which it loses ; for vegetables live at the expense of the carbonic acid that is emitted by volcanoes, as well as of that which is exhaled by animals. It is not, therefore, as purifiers of the air that plants are so immediately and especially necessary to animals; it is rather as supplying them, and that incessantly, with organic matter ready prepar- ed for assimilation, which they may burn or other- wise consume to their advantage. The service which vegetables render us in purify- ing the air we breathe is necessary, without doubt, but OF ORGANIC NATURE. 35 it is so remote that our gratitude is little. There is another service, so immediate, so intimate, that did it fail but for a single year, the earth would be depopulated ; it is that which these same vegeta- bles confer in preparing food for us, and for the whole animal creation. It is here especially that the connection of the two kingdoms of nature is remarkable. Annihilate vegetation, and forthwith animals perish of hunger; the entire realm of or- ganization must necessarily disappear with that of vegetation. Yet we have said that the carbonic acid of the atmosphere varies from youths to Tooootns of its bulk. These variations are easy to observe, and they occur very frequently. May not this be a phenomenon proclaiming the influence of animals which introduce this acid into the air, and that of plants which abstract it ? No ; you are aware of the fact that the pheno- menon in question is simply meteorological. It is with carbonic acid as with watery vapor, which is formed at the surface of the ocean to be condensed elsewhere, to fall back as rain or dew, and to be raised again in the form of vapor. This water, which is condensed and falls, dis- solves and precipitates the carbonic acid; the water which evaporates, raises and abandons the same gas to the air. 36 THE BALANCE It would, consequently, be of great interest, me- teorologically, to contrast the variations of the hygrometer with those of the seasons, and the state of the heavens with variations in the quantity of carbonic acid contained in the air; but hitherto all tends to provethat the rapidvanations observed con- stitute simple meteorological incidents, and by no means, as was once supposed, physiological incidents, which, isolatedly considered, would very certainly produce variations vastly more slow than those that are actually noted, whether in cities or the country. The air is, therefore, a mighty magazine whence plants for a long time may draw all the carbonic acid they require for their wants, and where ani- mals, for a still longer period, will find all the oxy- gen they can consume. The atmosphere, we conclude, then, is a mixture which incessantly receives and incessantly furnishes oxygen, nitrogen, and carbonic acid, by a thousand exchanges, of the nature of which it is now easy to form a right conception, and of which a rapid sketch will enable us to appreciate the most re- markable circumstances. III. Let a seed be thrown into the earth; let it ger- minate and grow ; let the new plant be followed until it have borne flowers and fruit in its turn and OF ORGANIC NATURE. 37 it will be seen by proper analyses, that the original seed in producing the new being has fixed carbon, hydrogen,"oxygen, nitrogen, and certain earthy particles or ashes. Carbon.—The carbon of vegetables is mainly derived from carbonic acid, whether it be taken from that of the air, or from that which the spon- taneous decomposition of manure evolves incessant- ly in contact with their roots. But it is from the air especially that plants derive their carbon; how can this be otherwise, indeed, when the enormous quantities of carbon which trees, the growth of a century, for example, have laid up, are contrasted with the very limited extent to which their roots extend? Very certainly, when the acorn whence sprang the oak, which is now our admiration, germinated a hundred years ago, the soil where it fell and struck root did not contain the millionth part of the charcoal which the oak now encloses. It is the carbonic acid of the atmosphere which has furnished all the rest; that is to say, almost the whole mass of the noble tree. (9) But what can be more clear or conclusive upon this subject than that experiment of M. Boussin- gault, in which peas sown in sand, watered with distilled water, and fed by the air alone, nevertheless found in this air all the carbon necessary to 4 38 THE BARANCE their developement, flowering, and fructification ? All plants fix carbon, and all obtain it from car- bonic acid, whether this be derived directly from the air by the leaves, or be obtained by the roots from the ground, watered with rains impregnated with carbonic acid from the sky, or supplied by the gradual decomposition of organic particles and manures in the soil. These facts are proved without difficulty. M. Boussingault observed the leaves of a vine, includ- ed in a glass flask, to take the whole of the car- carbonic acid from a stream of air that was sent through the vessel, however rapid the current. And M. Boucherie, on his part, observed enormous quantities of carbonic acid, which had certainly been taken up from the soil by the roots, to escape from the trunks of trees cut across when they were in full sap. But if the roots derive this carbonic acid from the soil—if it passes into the trunk, and from thence into the leaves, it ends by being exhaled, without change, into the atmosphere, if no new force intervenes. Such is the case with plants vegetatino- in the shade and during the night season; the carbonic acid of the soil permeates their tissues and is diffus- ed in the air. Plants are commonly said to pro- duce carbonic acid during the night: this is incor- rect : plants only then transmit unchanged the car- OF ORGANIC NATURE. 39 bonic acid which their roots have pumped up from the soil. But, suppose this carbonic acid, whether derived from the soil or from the atmosphere, to be in con- tact with the leaves and green parts, and the light of the sun to fall on these, immediately the w7hole scene is changed : the carbonic acid disappears; minute bubbles of oxygen are evolved from every point of the leaves, and the carbon is fixed in the tissues of the plant. And it is a point most worthy of remark and fitted to arouse reflection, that these green parts of vegetables, the only ones that have been found capable of exhibiting this wonderful phenomenon, the decomposition of carbonic acid, are also pos- sessed of another property not less peculiar, not less mysterious. If we attempt to transfer their images to a pre- pared plate in the apparatus of M. Daguerre, the green parts are found not to be reproduced, not to be figured ; it is as if the whole of the chemical rays, essential to the photographic phenomenon, had disappeared, had been absorbed and retained by the leaf. It would seem, therefore, that the chemical rays of light vanish' entirely in the green parts of plants, — an extraordinary absorption, without doubt, but easily explicable when the enormous 40 THE BALANCE expenditure of chemical force necessary to the de- composition of a substance so stable as carbonic acid is considered.* Let us next inquire concerning the part played by the carbon thus wonderfully fixed by vegeta- bles. What is its business—what its destination 1 For the major part, unquestionably, it combines with water or its elements, and thus gives origin to substances of the highest consequence in the economy of plants. ;■'» Twelve atoms of carbonic acid being decom- posed, and abandoning their oxygen, there will re- sult 12 atoms of carbon, which, with 10 atoms of water, will compose either the cellular or the lig- neous tissue of plants, or the starch and the dex- trine which are their derivatives. In every plant, consequently, almost the whole of its framework, formed as it is of cellular tissue, ligneous tissue, and starch or gummy substances, is represented by 12 atoms of carbon combined with 10 atoms of water. (10) Woody fibre, which is insoluble in water; starch, which, with boiling water, forms a jelly; and dextrine, which dissolves so readily both in cold and boiling water, therefore, constitute, as M. Pay en has so excellently shown, three bodies having precisely the same composition, but diver- sified by a different atomic arrangement. * See Appendix D. OF ORGANIC NATURE. 41 With the same elements, consequently, in the same proportions, the vegetable world elaborates the insoluble walls of cells, cellular tissue and vessels, as well as the starch which it stores up as aliment around its buds and embryos, and the so- luble dextrine which the sap transports from one part to another to supply the various wants of the plant. Admirable fecundity, which can fashion from the same elements three different substances, and has power, in addition, to transmute them one into another, writh the least possible expenditure of powder, as often as occasion requires the change! It is still by means of carbon, combined with water, that the saccharine substances are produced, which are so frequently deposited in the organs of plants, for the special ends which we shall speak of by and by. Twelve atoms of carbon and 11 atoms of water form cane-sugar; 12 atoms of carbon and 14 atoms of wTater form grape-sugar. These ligneous, amylaceous, gummy, and sac- charine matters, which carbon, in the nascent state, can produce by combining with water, play so great and essential a part in the life of plants that, taking them into consideration, it is not diffi- cult to explain the important part performed by the decomposition of carbonic acid in the vegeta- ble world. 4* 42 THE BALANCE Hydrogen.—-In the same way as plants decom- pose carbonic acid, appropriating its carbon, and with this forming the several neutral substances which constitute almost their entire mass, so do they also decompose water and fix its hydrogen, in order that they may form certain compounds in which this element predominates. This fact fol- lows clearly from the experiments of M. Boussin- gault upon the vegetation of peas in close vessels. It is even proclaimed more strikingly in the pro- duction of the fat and volatile oils which are so frequently met with in different parts of vegetables. and are well known to be so rich in hydrogen. This can only come from water, inasmuch as vege- tables have no other hydrogenous compound to feed on save water. (11)* The hydrogenous substances,' to which the fixa- tion of the hydrogen derived from water gives rise, are employed by plants for various subordinate purposes. Volatile oils serve to defend them, or their parts, from the attacks of insects; the grease, or fat oils with which seeds are so commonly sur- rounded or impregnated, serve as materials for combustion, and produce heat at the period of germination ; the wax with which the leaves and the fruit are covered, renders them impermeable to water, &c. But these various purposes are evidently no f FVe Appendix F. OF ORGANIC NATURE. 43 more than adventitious, or accidental, in the life of plants : hydrogenous compounds are therefore much less necessary, much less frequent in the vegetable kingdom than the neutral compounds of carbon and water. Mtrogen or Azote.—Every plant fixes nitrogen during its life, whether it obtains this element from the atmosphere, or from manures added to the soil. In either case, it seems probable that the azote only enters the plant, is only consumed, under the form of ammonia or nitric acid. The experiments of M. Boussingault have shown that certain plants—the Jerusalem arti- choke among the number—abstract large quanti- ties of azote from the air; and that others, on the contrary, such as wheat, depend upon manure for the supplies of this element which they require. What an important distinction is this for agricul- ture ! Is it not obvious that we must begin by raising plants that assimilate the azote of the at- mosphere, with these feed animals which shall fur- nish us with manure, and then apply this to the culture of those vegetables that are dependent on manure for their nitrogen ? One of the first problems in agriculture is to procure supplies of nitrogen at a cheap rate.* With regard to carbon, there is no cause for so- licitude,—nature has provided that in ample * See Appendix F. 44 THE BALANCE abundance ; the air and every shower of rain are charged with it. But it is otherwise with refer- ence to nitrogen ; the azote of the air may be un- assimilable, and the ammoniacal and nitrogenous salts which rain-water contains may not be in suf- ficent quantity. It is indispensable, therefore, to surround the roots of almost every plant whose culture is of importance to mankind with manures rich in azote, as enduring sources of ammonia or of nitric acid, which the plants appropriate in pro- portion as they are produced. To do this, as is well known to all, is one of the grand causes of expense in agriculture, one of the grand obstacles to its progress; for we are generally dependent upon, and have only access to, the manure which we can severally produce. But chemistry is so far advanced in this direction, that the problem re- quiring the production of a purely nitrogenous manure cannot long remain unresolved. M. Shattenmann, the able director of the manu- factories of Bouxvillers in Alsace, M. Boussingault, and M. Liebig, have directed attention particularly to the part played by ammonia in nitrogenised manures; and recent inquiries have shown that the nitric or azotic acid of the nitrates also deserves especial consideration. (12) But what may be the use of this nitrogen which plants seem to require so imperiously ? The re- OF ORGANIC NATURE. 45 searches of 1*1. Payen answer this question in part, for they show us that all the organs of vegetables, without exception, begin to be formed out of a nitrogenised matter analogous to fibrine, with which the cellular tissue, the woody tissue, and the amylaceous tissue itself, are associated at a later period. This azotised matter, the true source of all the parts of plants, is never destroyed; it is always to be found, however abundant the non- azotised matters, which have been subsequently interposed between its proper particles, may be. The azote that is fixed by vegetables, therefore, serves for the production of a concrete fibrinous substance, which forms the rudiments of every one of their organs. It serves, moreover, for the formation of the liquid albumen, dissolved in all the coagulable juices of plants, and of the caseum, frequently confounded with albumen, but so easily distinguish- able from it, which forms so important a principle in many vegetables. Fibrine, albumen, caseum exist, then, in plants. (13) These three principles, which are further identical in their elementary composition, as M. Vogel showed long ago, present a singular analogy to the ligneous tissue, starch, and dextrine. Fibrine, in effect, is insoluble, as is the woody 46 THE BALANCE fibre; albumen coagulates with heat like starch; caseum is soluble, like dextrine. These azotised matters are further neutral, as well as the three parallel non-azotised matters ; and we shall find that they are as abundant, and play the same parts in the animal kingdom, as these last do in the vegetable world. Moreover, in the same way as it is necessary, in the formation of non-azotised neutral substances, to have carbon combined with water, or its ele- ments ; so, to form the neutral azotised matters in question, it is sufficient to combine carbon and ammonium with the elements of water: 48 atoms of carbon, 6 of ammonium, and 15 of water, con- stitute fibrine, albumen, and caseum. Thus, in either case, the substances that are re- duced, carbon and ammonium, added to the ele- ments of water, suffice to form the matters which engage us, and their production enters naturally into the circle of reactions which vegetable nature appears above all fitted to produce. The office of the czote in plants is therefore worthy of the most serious attention, inasmuch as it is this element which serves for the formation of fibrine—a principle that is found as the matrix of every organ, and for the formation of albumen and caseum, substances that occur so extensively distributed throughout the bodies of all plants, and OF ORGANIC NATURE. 47 that animals assimilate or modify to meet their peculiar wants. It is in plants, consequently that the true labo- ratory of organic chemistry resides; carbon, hy- drogen, ammonium, and water, are the elements they work upon ; and woody fibre, starch, gums, and sugars, on the one hand, fibrine, albumen, caseum and gluten, on the other, are the products that present themselves as fundamental in either organic kingdom of nature — products, however, which are formed in plants, and in plants only, and merely transferred by digestion to the bodies of animals. Ashes.—An immense quantity of water passes through a plant during the term of its existence. This water evaporates from the surface of the leaves and necessarily deposits, as residue, the salts which it held in solution. These salts constitute the ashes of plants, products evidently derived from the soil, and restored to it again by vegetables after their death. As to the form in which these mineral products are deposited in the tissues of plants, there is no- thing more variable. Let us only remark, in this place, that one of the most frequent and abundant consists of the pectinate of lime, which M. Jacque- lain detected in the ligneous tissues of the great majority of plants. (14) 4b THE BALANCE IV. If plants in the shade act as simple filters, which water and carbonic acid gas permeate; if under the influence of solar light, they take upon them- selves the office of reducing apparatus which de- compose water, carbonic acid, and oxide of ammo- nium ; there are still certain epochs and certain or- gans in which plants perform another, and entirely opposite part. If the business be to have an embryo produced, a bud evolved, a flower fecundated, the plant which has hitherto absorbed solar light, which has de- composed carbonic acid and water, changes im- mediately in its procedure ; it begins to burn car- bon and hydrogen; it produces heat; in other words, it manifests some of the principal characters of aniraality.* But, here, a remarkable circumstance presents itself. In the process of germination of wheat, bar- ley, &c, there is a great evolution of heat, carbonic acid, and water. The starch of the grain changes first into gum, then into sugar, and then it disap- pears, producing the carbonic acid in question. Does a potato sprout, it is still the starch of the tuber that changes into dextrine, then into sugar; and this in its turn, in the process of its decompo- sition into^rboiux_acidJ_eyol^^ * See Appendix G. OF ORGANIC NATURE. 49 would, therefore, seem to be the immediate means by which vegetables evolve heat, when it is re- quired. How is it possible not to be struck with the co- incidence of the following facts 1 Fecundation is always accompanied by an evolution of heat; flowers respire by producing carbonic acid; they, therefore, consume carbon ; and, if it now be asked whence this carbon proceeds, we find that the su- gar which has been accumulated in the plant— the stem of the sugar-cane, to choose a single and very remarkable instance,—has disappeared en- tirely, when the flowering and fructuation have been accomplished. In the beet-root, in the same way, the quantity of sugar goes on increasing up to the time of flowering ; from this time it decreas- es ; and when the plant is in full seed, not a trace of sugar can be shown in the root. In the parsnip, carrot, turnip, &c, precisely similar phenomena are observed. At certain epochs then, in certain organs, a plant becomes an animal—like this, it becomes an appa- ratus of combustion; it burns carbon and hydro- gen ; it produces heat. At these periods, however, it destroys an abun- dance of saccharine matter, which it had previously engendered slowly and stored up. Sugar, or starch converted into sugar, is therefore the primary sub- 5 50 THE BALANCE stance by means of which vegetables evolve the heat that is necessary to the performance of some of their functions. , And, if we now observe with what instinct ani- mals, and man himself, proceed to select as food the very parts of vegetables in which they had laid up their stores of sugar and starch as means for the evolution of caloric, to meet their own wants, does it not become infinitely probable that sugar and starch are also destined to play the same part in the animal economy, to be burnt in the process of respiration, and to develope the heat which accom- panies the act ? To resume: so long as the plant preserves its habitual character, it derives from the sun heat, light, and chemical rays, which it stores up. It re- ceives carbon from the air, takes hydrogen from water, nitrogen or ammonium from ammonia or nitric acid, and various salts from the soil. With these elementary or mineral substances it fashions organic substances, which accumulate in its tissues. The substances so fashioned and accumulated are either ternary compounds, lignen, starch, gum, sugar, oils or fats; or they are quaternary com- pounds, fibrine, albumen, caseum, gluten. So far, the vegetable is therefore a constant pro- ducer ; but if at particular times, and in order to accomplish certain functions, it become a consumer, OF ORGANIC NATURE. 51 it exhibits precisely the same phenomena as the animal is about to present us withal. (15) V. An animal does, in fact, constitute an instru- ment of combustion, whence carbonic acid is inces- santly disengaged, and where, consequently, carbon is incessantly consumed. (16) You are aware that we have not been arrested by the phrase, cold-blooded animals, which would seem to imply that there were animals devoid of the power of producing heat. The rod of iron, which is burnt in oxygen gas, produces a heat which no one will deny; but it requires reflection and some science to perceive that the iron which rusts slowly in the air disengages just as much heat, although its temperature never varies sensibly from that of the surrounding atmosphere. Phosphorus alight burns brilliantly, and produces abundance of heat; phosphorus in the cold still burns, but it is with little lustre, and the heat which it evolves was for a long time denied. Now, there are some animals which burn a large quantity of carbon in a short time, and preserve a sensible and considerable excess of heat above sur- rounding bodies,—these are what are called warm- blooded animals. There are other animals again, which burn a much smaller quantity of carbon in 52 THE BALANCE a given interval of time ; and they have so slight an excess of temperature above surrounding ob- jects, that it is difficult or impossible to perceive it. Nevertheless reason leads us to see the most constant character of animality in this combustion of carbon, with formation of carbonic acid and evolution of heat, which are its necessary conse- quences. It matters not whether the question be of supe- rior or inferior animals, whether the carbonic acid be exhaled from the lungs, gills, or the skin, the phenomenon is the same, the end and influence are identical. At the same time that they burn carbon, animals also consume hydrogen; this is a fact, proved by the constant disappearance of oxygen which oc- curs in the course of their respiration. Animals, further, constantly exhale azote. I in- sist particularly upon this point, with an especial view to getting rid of one of the illusions which 1 hold most inimical to your progress. Some observ- ers have admitted an absorption of azote in the course of respiration ; but this never occurs save in connection with circumstances which render it more than doubtful. The constant phenomenon is the exhalation of this gas, as M. Despretz has very well observed. (17) OF ORGANIC NATURE. 53 We must conclude then, and with a full assur- ance of the fact, that we never derive nitrogen from the air ; that the air is never an aliment for us; that all we do, is to take from it the oxygen which is requisite with our carbon to form carbonic acid, with our hydrogen to form water. The nitrogen we exhale, then, proceeds from our food, and from our food only. The nitrogen of the atmosphere might, in the general economy of na- ture, be absorbed in the course of thousands of ages by plants, which, like the Jerusalem artichoke, de- rive their azote immediately from the air. But this is not all the azote which animals throw off. Each of us here assembled excretes, on an av- erage, according to the estimate of M. Lecanu, 15 grammes, or nearly 4 drachms of azote, with his urine every day. The azote here is obviously de- rived from our food, as are the carbon and hydro- gen which we burn. (18) Under what form does the nitrogen escape ? Un- der that of ammonia. And here we have another of those wonderful arrangements which never fail to fill the mind with admiration of the simplicity of the means which Nature brings into play in work- ing out her very greatest ends. If, in the general economy of things, we render to the air its con- stituent'azote which certain plants may one day ap- propriate, it might have been anticipated that we 5* 54 THE BALANCE should also be bound to restore the ammonia we have received, seeing that this is a compound so necessary to the existence, to the perfect evolution of the greater number of plants. Now, this is precisely what is effected by the uri- nary secretion ; which is neither more nor less than a solution of ammonia restored to the earth or the atmosphere. But, need I observe, that the urinary organs would have been affected in their functions, in their vitality, by the contact of so caustic a substance as ammonia, or even carbonate of ammonia 1 provi- dent Nature has, therefore, caused us to excrete urea. But urea is still a carbonate of ammonia ; that is to say, it is a compound of carbonic acid, such as we expire, and ammonia, in the shape in which it is craved by plants. But the carbonate of ammo- nia has here lost, or is without hydrogen and oxy- gen in the proportions that would form 2 atoms of water; deprived of which it constitutes urea, a neutral (19) and inert substance, which can pass through the delicate structure of the kidneys, the ureters, and the bladder, without irritating or in- flaming them. Brought into contact with the air, however, urea speedily undergoes a true fermentation which re- stores to it the 2 atoms of water and turns it into or- OF ORGANIC NATURE. 55 dinary carbonate of ammonia,—an extremely vol- atile substance, apt to exhale into the air; very so- luble, also, and ready to be caught and precipitated in dews and rains ; evidently destined, therefore, to travel from the earth to the atmosphere, from the atmosphere to the earth, until, seized upon by the roots of a plant, and elaborated there, it is convert- ed anew into organic matter. Let us add one touch more to this picture. In the urine, Nature has placed side by side with the urea, traces of an albuminous or mucous substance, so slight that they almost escape detection by ana- lysis. Nevertheless, this infinitely minute quantity of matter undergoes a change when it comes into contact with the air, becomes one of those ferments which are found distributed over the whole of or- ganic nature, and determines the conversion of the urea into ordinary carbonate of ammonia. (20) These ferments which have so frequently attracted our attention, and which preside over the most re- markable metamorphoses of organic chemistry, will furnish us with a theme for our lectures of another session. We excrete urea, then, accompanied with this ferment, with this contrivance, which, coining into play at the proper moment, will convert the urea into carbonate of ammonia. If we refer the carbonic acid of the urea to the ob THE BALANCE general phenomenon of animal combustion, to which, indeed, it belongs of right, we shall have ammonia remaining as the characteristic product of the renal secretion. With reference to the lungs and skin, then, we have carbonic acid, water, and azote; To the urine, ammonia. Such ar^ the constant and necessary excretions of the animal body. And these are precisely the elements which ve- getables require and turn to use, just as the plant, in its turn, restores to the air the oxygen which the animal had consumed. Whence have the carbon and the hydrogen burnt by an animal, the azote, free or converted into car- bonate of ammonia, which he exhales, been de- rived 1 Unquestionably from his food. In studying the function of digestion from this point of view, we have been led to regard it in a manner much more simple than is usually done, and which we shall now recapitulate in a few words. When, in fact, we have had it demonstrated to us that an animal creates no organic matter; that he is limited to assimilating it, or to expend by burning it, there was no longer any reason to search for all those mysteries in digestion which are very certainly not to be found there. OF ORGANIC NATURE. 57 Digestion, in a word, is a simple process of ab- sorption. Soluble substances pass irrto the blood, for the major part without alteration; insoluble substances make their way into the chyle, having been sufficiently comminuted to be imbibed by the lacteal vessels. Moreover, the object of digestion is evidently to restore to the blood a material fitted to supply our respiration with the 2± or 3f drachms of carbon, or an equivalent quantity of hydrogen, which each of us burns in the course of an hour (21), and also to purvey the 15 grains of azote per hour which are exhaled by the lungs, the skin, or the kidney. Amylaceous matters are, therefore, changed into gum and sugar, and these substances are absorbed. Fatty matters are subdivided, formed into an emulsion, and in this way pass into the vessels, sub- sequently to form deposits, which the blood resumes for the purpose of combustion, as they are required. (22) The neutral azotised substances, fibrine, albu- men, and caseum, dissolved at first, and then pre- cipitated, find their way into the chyle in a state of extreme subdivision, or dissolved anew. (23) Animals would, therefore, seem to receive, and to assimilate almost unchanged the neutral azotised substances which they find ready-formed in the ve- getables or other animals upon which they feed : 5S THE BALANCE they receive fatty substances from the same sources; they receive amylaceous, or saccharine substances, which are in the same predicament. (24) These three grand orders of substances, the ori- gin of which must always be referred to vegeta- bles, are divided into assimilable products,—fibrine, albumen, caseum, fat, which serve for the growth or renovation of organs ; and into combustible pro- ducts, sugar and fats, which are consumed or burnt in respiration. An animal consequently assimilates, or he de- stroys, organic substances ready formed ; he creates or forms none. Digestion introduces these already prepared or- ganic matters into the blood ; assimilation appro- priates those that are azotised; respiration burns the rest. If animals, then, possess no special power of pro- ducing organic substances, have they not, at least, the special and wonderful power of producing ca- loric without expenditure of matter, which has been ascribed to them ? You have seen, in our discussion of the experi- ments of Messrs. Dulong and Despretz—you have seen positively that they have not. These excel- lent experimenters have supposed that an animal, inclosed in a calorimeter and surrounded with ice, or ice-cold water, quits the machine with precisely OF ORGANIC NATURE. 59 the same temperature as he entered it,—a thing impossible, and well known now. It is the cooling of the animal, of which they took no note, that ex- presses in their tables the excess of heat ascribed by them and the generality of physiologists after them, to a calorific power peculiar to the animal, and independent of respiration. (25) It is a matter of demonstration to me that all the heat wThich an animal engenders proceeds from the respiration, and that its amount is exactly measured by the quantity of carbon and of hydrogen con- sumed. It is matter of demonstration, in a word, that the poetic likening of an animal to a locomo- tive steam-engine, rests upon more serious grounds than has been generally supposed. In one, as well as the other, there are combustion, heat, and mo- tion, three phenomena connected and in relation. Considered in this way, the animal machine comes to be much more easily understood ; it is the medium between the vegetable world and the atmosphere; it derives all its elements from the former, it throws out all its excretions, and, finally, is itself decomposed into the latter. Shall I recall to your recollection in what manner we have regarded respiration ; a process more com- plex than it was held to be by Laplace and Lavoi- sier and Lagrange, but which every addition to its complexity tends to bring more and more into the 60 THE BALANCE category of the laws which govern inanimate nature 1 You have seen that the venous blood dissolves oxygen and disengages carbonic acid; that it becomes arterial, without any trace of a rise of temperature. It is not, therefore, in becoming ar- terial merely that the blood produces heat. But under the influence of the oxygen absorbed, the soluble principles of the blood are converted into lactic acid, as was perceived by M. Mitscher- lich, and by Messrs. Bourton, Charlard, and Frerny; the lactic acid formed, is itself converted into lactate of soda, and this by a true process of com- bustion is turned into carbonate of soda, which is immediately seized upon by a fresh portion of lac- tic acid, and so on. This slow and ceaseless succession of phenomena constitutes the true essence of respiration; it exhibits to us a remarkable instance of those slow processes of combustion, upon which M. Chevreul fixed the attention of chemists so long ago. The blood is oxygenated in the lungs; it actually respires in the capillaries of all the other organs, in which the combustion of carbon and the produc- tion of heat are especially accomplished. (26) One other reflection. To reach the summit of Mont-Blanc, a man spends two days of twelve hours each. In this time he burns, on an average, OF ORGANIC NATURE. 61 300 grammes (about 9^ oz. avoirdupois), of car- bon, or an equivalent quantity of hydrogen. Were a steam-engine employed to carry him thither, it would consume from 1000 to 1200 grammes (21b. 8 oz. to 31b. 2 oz. avoirdupoise) of carbon in the service. Considered as a machine, then, deriving the whole of its power from the carbon it consumes, the body of man is at least three or four times more perfect in its mechanism than the most perfect steam-engine. Our artificers and engineers have, consequently, much still to accomplish; and yet these numbers are of a nature calculated to prove that there is community of principle between the living engine and the other; because, if we take an account of all the losses inevitable in fire-machines, and so carefully and admirably guarded against in the human fabric, the identity of principle in their res- pective forces stands out clear and manifest to the eyes. (27) But we have gone far enough in a course in which your own reflections already take the lead of me, and where your recollections leave me nothing to add. If we recapitulate, we shall see that the primi- 6 62 THE BALANCE tive atmosphere of our globe has formed itself into three great parts or masses: One, constituting the atmospheric air of the pre- sent time; a second, represented by plants; a third, by animals. Between these three masses continual changes are effected; matter descends from the air into veoe- tables, penetrates in this way into animals, and returns to the air in proportion as they consume or apply it to their purposes. Green vegetables constitute the grand laboratory of organic chemistry. They are the agents which, with carbon, hydrogen, azote, water, and oxide of ammonium, slowly form the most complex organic substances. Under the form of heat, or of chemical rays, they receive from the sun the force which enables them to accomplish this great work. (28) Animals assimilate or absorb the organic sub- stances which plants have formed. They alter them by degrees; they destroy or decompound them. New organic substances may arise in their tissues, in their vessels; but these are always sub- stances of greater simplicity, more akin to the ele- mentary state than those they have received. They decompose, then, by degrees, the organic matters created by plants. They bring them back by degrees towards the state of carbonic acid, OF ORGANIC NATURE. 63 water, azote, and ammonia, a state which admits of their ready restoration to the air. In burning or destroying these organic substances, animals always produce caloric, which, radiating from their bodies into space, goes to supply that which vegetables had absorbed and fixed. Thus all that the atmosphere yields to plants, plants yield to animals, animals restore to the air. Eternal round, in which death is quickened and life appears, but in which matter merely changes its place and its form ! The crude and formless mass of the air, gradually organized in vegetables, passes, without change, into animals, and becomes the instrument of sensa- tion and thought; then, vanquished by this effort, and, as it were, broken, it returns as crude matter to the source from whence it had come. Allow me, in concluding this discourse, briefly to recapitulate the opinions which, to my mind, present themselves but as consequences and necessary developments of the grand route which Lavoisier marked out for modern chemistry (29) ; allow me to speak as he spoke of his fellow-laborers and friends. If in my course—if in the foregoing summary I have been led to adopt, without quoting his name, the opinions or experiments of M. Boussingault, it 64 THE BALANCE OF ORGANIC NATURE. is only because the habit of freely communicating our ideas, our observations, our modes of viewing every subject that interests us, has engendered a community of opinion between us, in which it would be difficult for each to specify what belongs to him in particular. In strengthening with his name, with his author- ity, these opinions and their consequences, in stating to you that we labor zealously, now together, now severally, to give precision to all these facts, to illustrate by experiment all these results, it is to show you how anxious I am to bear you out in the interest you have taken in the labors of the session that now ends. I thank you heartily. Your countenance gave me the courage needful to undertake long series of researches, and if aught useful to the progress of humanity result from the labor, to you, and to that intelligent kindness with which you have always upheld me, and for which I shall ever feel most grateful, be all the honor. DOCUMENTS. The principal data upon which the various con« siderations developed in the preceding discourse are grounded, have been united in the following notes. I. Composition of Carbonic Acid.—In assuming, with Prout, the composition of carbonic acid to be 16 of oxygen and 6 of carbon, or 8 of the former and 3 of the latter of these substances, I rely upon experiments performed by burning pure graphite and the diamond in oxygen gas. Here are the numbers obtained in the experi- ments which I performed along with M. Stas, Pro- fessor in the Military School of Brussels:— Combustion of the Natural Graphite of Ceylon. Graphite consumed. Carbonic Acid obtained. Relations between the and the Carbon. 1.000 3.671 8 2.995 0.998 3.660 8 3.005 0.994 3.655 8 2.999 1.216 4.461 8 2.998 1.471 5.395 8 2.999 Mean - - 2.9990 6* 66 COMPOSITION OF CARBONIC ACID, ETC. Combustion of the Artificial Graphite of the Smelt' ing Furnace. Graphite consumed. Carbonic Acid obtained. Relations between the Oxygen and the Carbon. 0.992 3.642 8 : 2.995 0.99S 3.662 8 : 2.997 1.160 6.085 S : 8.003 1.465 5.365 8 : 3.005 Mean - - 8 : 2.9993 Combustion of the Diamond. Diamond Carbonic Acid Relations between the Oxygen cons'imed. obtained. and the Carbon. 0.708 2.598 8 : 2.997 0.864 3.165 8 : 3.000 1.219 4.465 S : 3.004 1.232 4.517 8 : 3.000 1.375 5.041 8 : 3.000 Mean - - 8 : 3.0002 These experiments, repeated in Germany by two excellent and practised chemists, Messrs. Erdmann and Marchand, having given exactly the same re- sults, I hold it as established that oxygen and car- bon combine in the simple relations of 8 : 3, or 16 : 6, to form carbonic acid. II. Composition of Water.—We know of no pro- cess by which we can weigh a few grammes of hydrogen, and having burned them, proceed to weigh the water which they might form in their combustion,-the sole means of attaining, with COMPOSITION OF WATER, 67 reference to the composition of water, the same high degree of precision to which we arrive in burning the diamond, when the composition of car- bonic acid is the question. The experiments which I performed with M. Stas were based upon the reduction of oxyde of copper by means of an undetermined quantity of hydrogen. The oxygen furnished by the oxyde was weighed, and again, the water which was formed was weighed. Here are the numbers ob- tained :— Oxyeen given off by the Water Relations between the O Oxide of Copper. obtained. and the Hydrogen. 13.179 14.827 8 : 1.0004 20.362 22.905 8 : 0.9992 20.495 23.053 8 : 0.9998 57.004 64.044 8 1.0004 76.364 85.960 8 : 1.0049 43.571 49.047 8 1.0050 34.811 39.178 S 1.0036 45.887 51.623 8 ■ 1.0000 60.031 67.586 8 1.0066 51.838 58.322 8 1.0003 52.508 59.078 8 . 1.0009 59.789 67.282 8 1.0026 62.090 69.899 8 : 1.0061 51.838 58.390 8 : 1.0068 56.483 63.517 8 1.0046 36.789 41.390 8 : 1.0005 34.162 38.458 8 1.0058 32.133 36.175 8 : 1.0060 30.827 34.677 8 0.9993 Sum 841.161 945.441 Mean 8 1.002 68 COMPOSITION OF OXIDE OF AMMONIUM. From the mean of these experiments, water would, therefore, appear to be composed of 8 of oxygen and 1 of hydrogen. In publishing them with all the details necessary to their repetition, we express- ed the wish that they might speedily be controlled by methods of still greater delicacy. Both in a philosophical and practical point of view, it is of the greatest consequence that the composition of water should be definitely fixed by procedures of irreproachable precision—a consummation which cannot be obtained without performing several series of syntheses analogous to those that have been reported above. III. Composition of Oxide of Ammonium.—M. Ampere has proposed to consider all ammoniacal products, as formed by a species of compound me- tal, ammonium. This is one of the happiest thoughts which this illustrious individual has left to che- mistry. Combined with 1 atom of oxygen, ammonium forms the oxyde of ammonium, which, when free, always undergoes transformation into one atom of water and 1 atom of ammoniacal gas. The composition of water being known, we have only to determine that of ammonia, in order to have that of every ammoniacal compound, and even of ammonium itself. COMPOSITION OF AIR. 69 Now, ammonia is evidently formed by 3 volumes of hydrogen and 1 volume of azote. M. Boussin- gault and I have ascertained that the density of azote is 0.972, and that of hydrogen 0.0693. It follows that ammoniacal gas must contain Hydrogen - - 3 x 0.0693 = 0.2079 say 3 Azote - - - 1 X 0.9720 = 09.720 or 14.02 Ammoniacal gas - - - - 1.1799 17 Consequently 3 of hydrogen and 14 of azote constitute ammoniacal gas. Whence we have 4 hydrogen and 14 azote =18 ammonium 8 oxygen, 4 hydrogen and 14 azote = 26 oxide of am- monium a result which fixes at 14, or at ^ = 7, the weight of the atom of azote. IV. Composition of the Air.—By the process which M. Boussingault and I have lately employ- ed, we have been enabled to subject atmospherical air to a very rigorous analysis. The process allud- ed to consists in fixing the oxygen of the air by means of metallic copper, and weighing it, whilst its azote passes into a flask in which it is also weighed. Here are the numbers obtained in our several experiments:— 70 VEGETABLE TERNARY COMPOUNDS. 1000 Parts of Air contained by Weight: Oxygen. Azote. April 27. Weather fine - - 229.2 770.8 Paris, Ditto - - - - 229.2 770.8 — April 28. Weather fine - - 230.3 769.7 Paris. Ditto - - - - 230.9 769.1 — 29. Weather fine - - 230-3 769.7 — Ditto - - - - 230.4 769.6 — May 29. Rain ----- 230.1 769.9 — July 20. Noon, Rain - - - 230.5 769.5 — 21. Midnight, sky clear 230.0 770.0 — 24. Mid-day - - - 230.7 769.3 — Mean - - - - 230.2 769.8 — From the nature of the procedure, possible errors tend to diminish the proportion of oxygen. We can therefore say that, at Paris, there are at least 230.2 parts of oxygen in 1000 parts of air by weight. Analysis shows no difference in regard to air taken from a height of upwards of 9000 feet. As it is customary to consider the composition of the air by the volume, it is proper to add to these particulars, that from the numbers given, and hav- ing regard to the densities of oxygen and nitrogen, the air of our atmosphere must consist of 208 oxygen, and 792 azote, 1000 air. VEGETABLE TERNARY COMPOUNDS. 71 V. Composition of the principal Ternary Com- pounds of Vegetables.—The woody fibre, starch or dextrine, and sugar, comprise the chief substances which belong to this head. The elegant researches of M. Payen on the cellular and woody tissue have led him to a result of the highest physiological importance. Once freed from the matters deposited after its formation within the cells and vessels wThich it constitutes, it always presents the same composition. In the state of purity, it consists of 12 atoms carbon = 72 10 atoms hydrogen = 10 10 atoms oxygen = 80 162 Or otherwise, 100 parts of this tissue, which I have designated cellulose, contain, Carbon ------- 44-4 Water ------- 55-6 100-0 Such, then, is the composition of the general frame-work of vegetables; and such, also, is the composition of pure starch, and of dextrine or starch become soluble. Cane-sugar, in the state of sugar-candy, con- 72 VEGETABLE TERNARY COMPOUNDS. tains an additional atom of water. The analyses of Gay-Lussac and Thenard show it, in fact, to consist of 12 atoms carbon ----- 72 11 atoms hydrogen - - - - 11 11 atoms oxygen ----- 88 171 or 100 parts of the same sugar consists of Carbon ------- 42-1 Water.......57-9 100-0 Grape sugar, better known at the present time under the name of sugar of starch, and which I have called glucose, contains three additional atoms of water, thus :— 12 atoms carbon - - - - 72 14 atoms hydrogen - - - - 14 14 atoms oxygen - - - - 112 198 or referring this composition to 100 parts of this sugar, it consists of— Carbon....... 36-3 Water ---____ 63-7 100-0 QUATERNARY ORGANIC COMPOUNDS. 73 With 72 parts of carbon, proceeding from the reduction of carbonic acid, then, plants are able to form the following products, by merely combining it with different proportions of water : 72 carbon and 90 water form the cellular and lig- neous tissue 72 ---- 90 ------- starch and dextrine 72 ---- 99 ------- cane-sugar 72 ---- 108 ------ sugar of milk 72 ---- 128 ------ sugar of grapes, or of starch. Without entering into any consideration of the arrangement of these elements, we see, therefore, that with a single radical, carbon, and water, plants can produce the whole of these substances, so gene- rally contained in their organs. VI. Composition of the Neutral Quaternary Organic Substances.—Under this head we have fibrine, albumen, caseine, gluten, proteine, vitelline, legumine, gelatine, and chondrine. Gay-Lussac and Thenard, and Mulder at a later period, have paid particular attention to the analy- sis of these substances, and have arrived at conclu- sions which are generally correct. The particulars which follow are extracted from a paper, which I published in conjunction with M. Cahours {Annates de Chimie, &c. 3me Serie T. vi. p. 385). 7 74 QUATERNARY ORGANIC COMPOUNDS. It has been assumed in the body of the preceding lecture, that animals receive albuminous substances ready formed from plants: nothing is more conclusive in regard to this fact than the analysis of wheaten flour. As is well known, it separates by careful washing into two portions—gluten and fecula; but, besides these, it also contains albumen. The starch is, by and by, deposited, and the clear liquid, which floats above it, contains, in solution, the albumen, which is easily recognizable, and coagu- lates at a temperature of about 75° C. (167° F.) The gluten, which remains in the hand of the operator, is a complex substance, which contains not fewer than four distinct products; 1st, fibrine, which remains when it is treated with dilute boil- ing alcohol; 2d, caseine, which precipitates from the alcoholic solution when it cools; 3d, glutine, which is obtained as a residue on evaporating the alcohol; 4th, an aggregate of fatty matters, mixed with the three preceding substances. Fibrine.—It had, for some time, been generally allowed, that fibrine was a substance identical with albumen in point of composition. The repeated analyses of Mulder, and of Liebig and his pupils, all tend to this conclusion. The analysis of different kinds of fibrine has led us to another and a different inference. To pre- pare the fibrine destined for analysis, it was first QUATERNARY ORGANIC COMPOUNDS. 75 purified by long washing with cold water; it was then treated, first, with hot alcohol, and then with hot ether. The fibrine thus handled was dried and reduced to powder; it was then subjected to re- newed digestions in boiling alcohol and ether; finally, it was dried in vacuo, at a temperature of 140° C. (316° F.) As for the fibrine of wheaten flour, or that ob- tained from crude gluten, it had to be subjected to particHlar treatment, in order to be freed from the starch, which it includes mechanically, or the caseine, or the glutine, which blend with it ob- stinately. Mean of Analyses of Fibrine. Fibrine, exhausted by boiling water, has exact- ly the same composition as albumen; it consists, in fact, of 76 QUATERNARY ORGANIC COMPOUNDS. Carbon.......53-49 Hydrogen ------ 7-09 Azote.......15"88 Oxygen, &c. ----- 23-54 10000 Fibrine, thus treated, yields a particular sub- stance to the water, and loses ammonia by the boiling. The substance dissolved by the water differs from albuminous substances, both in point of composition and of properties; it also differs from gelatine, to which it has been likened, in this, that it does not set into a jelly; it precipitates with tannin, however, and with nitric acid. Its com- position is as follows :— Carbon.....- - 47-91 Hydrogen ------ 6-87 Azote ------- 14-96 Oxygen ------- 30-26 100-00 It may be represented by the following for- mulae :— C48 h« Az^ O22 C48 H40 Az" O22 Gelatine.—Gelatine differs from the substance last mentioned in point of composition. It con- sists of— QUATERNARY ORGANIC COMPOUNDS. 77 Carbon.......50-99 Hydrogen ------ 7-07 Azote ------- 18-72 Oxygen ------- 2322 100-00 Chondrine.—Chondrine, or the gelatinous sub- stance which cartilege yields to boiling water, ap- proaches closely in its composition to the soluble substance which fibrine yields under similar treat- ment. According to Mulder, it contains, Carbon, ------- 50-61 Hydrogen, ------ 6-58 Azote, ------- 14-44 Oxygen, -.....28-37 100-00 Mbumine.—To procure the albumine, which was made the subject of the following analysis, blood-serum or white of egg was precipitated by alcohol; the precipitate was exhausted by alcohol and by water. It was then dried, pulverised and digested anew, with alcohol and ether; finally, it was dried at a heat of 140° C. (316° F.) in vacuo. 7K QUATERNARY ORGANIC COMPOUNDS. Mean of Analysis of Albumine. From Serum of the Sheep From Serum of the Ox. From Scrum (if'tlie Calf. From Serum of* Man. Ofwhite of Egg. Of wheaten Flour. Carbon ..... 53.54 7-08 15 82 23 56 53 40 720 15 70 23-70 53 49 7 27 1572 2352 53 32 7-29 1570 23-69 53-37 7-10 15-77 23-76 53 74 711 15-66 23-50 10000 | 100-00 100 00 100 00 10000 10000 Caseine.—The caseine used for analysis was pre- pared from milk. It was precipitated by means of acetic acid, purified and dried in the same way as the albumine and fibrine. The caseine of the blood was procured by treat- ing a quantity of the clot with dilute boiling alco- hol, which dissolves it, but lets it fall on cooling. The caseine of wheat is obtained by treating gluten in the same way. Mean of Analysis of Caseine. Of Cow's Milk. Of Goat's Milk. Of Asses Milk. or Ewe's Milk. Of wo-man's Milk. Of Blood. Of Flour. Carbon .......... 53-50 7-05 15-77 23-68 53-60 7-11 15-78 23-51 53-69 7-14 16-00 23-20 53-52 7-07 15-80 23-61 53-47 7-13 15-83 23-57 53-47 7-09 15-87 23-29 53-46 7-13 16-04 23-37 100-00 100-00 10000 10000 100-00 100-00 10000 Glutine.—This name has been given to the sub- stance which alcohol dissolves when crude gluten is treated with this menstruum, and which does' not precipitate on the cooling of the fluid. To ob- QUATERNARY ORGANIC COMPOUNDS. 79 tain it pure, the alcoholic solution is evaporated to dryness: it is then carefully dried, powdered, and washed with boiling ether. Desiccated in vacuo at 140° C. (316° F.) it has the same composition as caseine and albumine. Mean of Analysis of Glutine. Carbon,.......53-27 Hydrogen, ------ 7-17 Azote,.......15-97 Oxygen, ......23-62 100-00 Proteine.—The name of Proteine was applied by Mulder to the pure animal matter, which enters into the composition of albumine and caseine, and is combined with sulphur or with phosphorus, bodies which have been confounded with oxygen in the preceding analysis. The proteine which was employed in the analysis which M. Cahours and I performed was procured from caseine and albumine. Mean of Analysis of Proteine. Carbon,.......54'37 Hydrogen,......7'12 AzoLe, ------- 15-93 Oxygen, „..---- 22-o8 10000 80 QUATERNARY ORGANIC COMPOUNDS. The formula C 1S, H 37, Az 12, 0 15, represents with great accuracy the composition of this sub- stance ; it, in fact, gives in 100 parts, C48....._-- 54-44 H a? -------- 6-99 Az 12.......15-88 O 15.......- 22-69 10000 Vitelline.—Vitelline constitutes the albuminous matter of the yolk of the egg. Mean of the Analysis of Vitelline. Carbon, ------- 51-60 Hydrogen, ------ 722 Azote,.....- - 15-02 Oxygen,......26-16 100-00 Whence is deduced the formula C 48 H 37 Az 12 O 15 -f 3 HO. Which gives:— C48---------------51.8 H" .---------. . ^ Azl2........15-1 018........260 1000 QUATERNARY ORGANIC COMPOUNDS. 81 Legumine.—M. Branconnot has so entitled an azotised substance which he extracted from peas, haricot beans, and lentils. There is an analogous matter, amandine, which is found in almonds and some other seeds. The substance which served for the following analysis was prepared by digesting the seeds which contain it with tepid water; the solution was precipitated by dilute acetic acid, the precipitate was dried, pulverized, exhausted by ether, and dried in vacuo at 140° C. Mean of Analyses of Amandine of different Seeds. From Sweet Al-monds. From ditto. From ditto. From Kernels of Plums. From Kernels of Apri-cots. From White Mustard Seed. From Hazel Nuts. Carbon — Hydrogen.. Oxygen.... 50-90 6-72 18-93 23-45 50-93 6-70 18-77 23-60 50-80 6-71 18-80 23-69 50-93 6-73 1S-64 23-70 50-72 6-65 18-78 23-85 50-83 6-72 18-58 23-87 50-73 6-95 18-76 23-56 100-00 100-00 100-00 100-00 100-00 10000 100-00 Mean of Analysis of Legumine of the Legumi- nosm. Of Lentils. Of Haricot Beans. 50-46 6-65 18-19 24-70 50-69 6-81 17-58 24-92 Carbon — Hydrogen.-- Azoie...... Oxygen, &c 100-00 100-00 10000 S2 QUATERNARY ORGANIC COMPOUNDS. The formula which would best represent the composition of amandine would be this :— C48 -------- 50-9 H 37 ._._.___ 6-5 Az is ------- - 18-5 O17 -------- 241 1000 VII. Principal Chemical Effects of Germination. —The following experiments of M. Boussingault show in what way plants behave at different periods of their germination, and what elements they abstract from the air or from water, and also what elements they themselves lose. 1. Germination and Cidtivation of Trefoil (Tre* folium pratense.)—In determining the composition of the seed and of the produce, M. Boussingault made use of the ordinary methods of organic ana- lysis ; here are the results he obtained :— Dry Trefoil Seed. i. 2. 3. Mean. Carbon, 0-4165 0-4930 0-4910 0-494 Hydrogen, 0-0583 0-0600 0-0549 0-058 Azote, 0-0699 0-0699 0-0699 0-069 Oxygen, 0-3468 0-3486 0-3557 0-350 Ashes, 0-0285 0-0285 0-0285 0-028 GERMINATION OF SEEDS. 83 Trefoil Seed freed from Ash. i. 2 3. Mean Carbon, 0-511 0-507 0-505 0-508 Hydrogen, 0-061 0-062 0-062 0-062 Azote, 0-072 0-072 0-072 0-072 Oxygen, 0-356 0-359 0-361 0-360 1000 1000 1000 1000 2. Germination of Trefoil—First Period.—The seed was made to sprout upon a porcelain dish ; when the radicle of each several seed had attained the length of from i to 1 centimetre (the 40th to the 20th of an English inch), it was carried to a stove heated to 100° C (212° F.) ; the complete desiccation was then secured in the usual way. The seeds which had not germinated were collect- ed and dried apart from the rest. The sprung seed dried and subjected to analysis yielded :— i. 2. Mean. Carbon, 0-497 0-501 0-499 Hydrogen, 0-064 0-060 0-062 Azote, 0-078 0-078 0-078 Oxygen, 0-331 0-331 0-331 Ashes, 0030 0-030 0-030 1000 1000 1000 84 GERMINATION OF SEEDS. The sprung seed freed from ashes gave:— 1. 2. Mean. Carbon, 0513 0-517 C-545 Hydrogen, 0-066 0-061 0-063 Azote, 0 080 0-080 0-080 Oxygen, 0-341 0-342 0-342 1000 1000 1000 From these analyses it results that Car. Hydr. Oxyg. Az. 1 ef trefoil seed containing....................0509 OOfiO 0-360 0072 Yielded 0-932 of germinated seed containing---0-480 0 05.) 0319 0074 Difference..................0.023 0-001 0 011 0 00-2 The analysis therefore shows that during the first period of germination, trefoil seed lost carbon and oxygen. 3. Germination of Trefoil—Second Period.—M. Boussingault has designated as the second stage in the germination of trefoil the epoch at which the green parts make their appearance. Each grain was transferred to the drying stone so soon as the seminal leaves were evolved. The shell of each seed was preserved and added to the sprung grain. The sprung grain dried and analysed at the second stage yielded :— l. 2. Mean. Carbon, 0-458 0-457 0-458 Hydrogen, 0-060 0-055 0-058 Azote, 0-084 0-084 0-084 Oxygen, 0-364 0-364 0-364 Ashes, 0-034 0-030 0-036 1000 1000 1000 GERMINATION OF SEEDS. 85 And freed from ashes :— i. 2. Mean. Carbon, 0-474 0-472 0-472 Hydrogen, 0-062 0-058 0-060 Azote, 0-087 0-0S7 C-087 Oxygen, 0-377 0-383 0-3S1 1000 1000 1000 Whence it follows that Carb. Hyd. Oxy. Az. 1 of trefoil-seed, containing...... 0-508 0-060 0-360 0-072 Yielded at the second stage of ger- ) 0.394 Q,C5Q Qm Q.Q72 mination 0-833, containing.... ) Difference........ 0-144 0-010 0-043 0-000 To reach this stage the trefoil-seed lost carbon and oxygen, as in the preceding experiment; but here the loss in carbon surpassed that in oxygen. Farther, an unequivocal loss of hydrogen is ap- parent. Finally, the azote which existed in the seed before germination is found in it after it has sprung. These analyses of germinated and ungerminated trefoil-seed seem to show that the phenomenon of germination is not so simple as it is generally be- lieved to be. We know from the elegant researches of M. de Saussure, that seeds in germinating change oxygen into carbonic acid. It has been further ascertained, that the acid gas formed has the same volume in the majority of cases as that of the oxy- 8 86. GERMINATION OF SEEDS. gen which has contributed to its formation ; whence the conclusion has been drawn that seeds in ger- minating lose a portion of their carbon without either absorbing or emitting oxygen. Even from the beginning of his experiments on the subject, however, M. de Saussure observed, that the total loss suffered by a seed which had germinated, al- ways exceeded that which can be ascribed to the carbon which combines with oxygen to form car- bonic acid. This learned chemist explained the excess of loss by the disengagement of a certain quantity of water, which, becoming free, is thrown off during the drying of the germinated grain. Analysis does not bear out this explanation. It indicates a very notable loss of oxygen during the germination of trefoil-seed, and shows, moreover, that, during the first stage, the loss cannot be due to water disengaged, inasmuch as there has been no sensible change in the hydrogen of the seed. During the second period, indeed, there is an elimi- nation of hydrogen ; but the quantity evolved is still not in proportion to the disappearance of oxy- gen ; it is too small to change the whole of the oxygen that is lost into water. And ihen, it has lately been found, that germinating seed has a con- siderably varied action upon the surrounding air. Some seeds, in germinating, change the oxygen of the air into exactly the same bulk of carbonic GERMINATION OF SEEDS. 87 acid ; but there are others which furnish sometimes less, sometimes more carbonic acid than there is oxygen consumed. * These results even vary with reference to the same species of seed, according to the stage more or less advanced of the germination. Analysis satisfactorily explains these varieties, which seem to depend on the phases through which a seed that germinates passes successively. It is enough, for example, to compare ungerminated trefoil-seed with the product of the first period, and this with that of the second. We then discover that the loss of carbon is common to the two pe- riods ; but we see at the same time, that the loss of oxygen seems to be stayed during the interval which separates the first from the second period. On comparing these two stages we have Carb. Hydr. Oxyg. 1 of seed................ 0 508 0-060 0-360 ^ ^"tagl £°*"3't and ? 0-480 0-059 0-319 I ^.0-041 , i contains S f becomes.. ) differ.O-002 And in the J 0.833...... 0.394 n.O50 0.317 second... ^ J Experiments upon Wheat.—The grain which was used in the following experiments had been grown in a good garden soil—a circumstance which ought to be noted, inasmuch as analysis proves the influence of manure on the quantity of azotised substance contained in the cerealia. The same wheat gathered from the best open-field S8 GERMINATION OF aUtlD*. wheat lands contains no more than 0-025 of azote, whilst that which we have under consideration here, from the mere circumstance of having grown in a more fertile soil, contains as much as 0-035 of the same element. 1. Compositim of Wheat. Dry. 1. 2. 3. Mean. Carbon.............0-453 0-455 0-458 0-455 Hydrogen...........0-059 0-055 0-056 0-057 Azote..............0-034 0-034 0-034 0034 Oxygen.............0.431 0-433 0-429 0-431 Ashes..............0-023 0-023 0-023 0023 1000 1000 1000 1000 Freed from Ashes. 1. 2. 3. Mean. Carbon.............0-464 0-465 0-469 0-466 Hydrogen...........0-060 0056 0058 0-058 Azote..............0045 00345 00345 0-0345 Oxygen............0-4315 0-4445 0-4385 0-4415 Ashes................ 10005 10000 10000 10000 2. Germination of Wheat—First Stage.—The germination was arrested immediately after the ap- pearance of the radicles; the young stems were scarcely visible. GERMINATION OF 8EEDS. 89 Composition of Germinated Wheat. Dry. Freed from Ashes. 1. Carbon...... 0-457 Hydrogen___ 0-057 Azote....... 0-036 Oxygen...... 0-426 Ashes....... 0-024 2. Mean. 1. Mean. 0-460 0-058 0-036 0-422 0-024 0-459 0-057 0-036 0-422 0-024 0-467 0-472 0-470 0-059 0-059 0059 0036 0-037 0-037 0-436 0-437 0-437 1000 1000 1000 1000 1000 1000 Summary:— Carb. Hydr. Oxyg\ Azote. 1 of wheat, containing.......0-466 0-058 0-441 0 035 Yielded of germinated wheat 0 974............. ^ 0 458 0 057 0 423 0 036 Difference........0 008. .0 001. .0 018, .0 001 During the first stage of the germination, the wheat appeared therefore to have gained a certain quantity of azote ; but the amount is so small, that the gain is even doubtful. The loss experienced by the wheat is almost entirely referable to the carbon and the oxygen. As in the first stage of the germination of trefoil-seed, the weight of the oxygen lost is much greater than that of the car- bon. The loss of hydrogen is within the limits of the possible errors of analysis. The elements lost during this first stage may be represented by water and oxide of carbon. 3. Germination of Wheat—Second Stage.—The sprouting was not arrested until the young stems had acquired the length of the seeds. 8* 90 VEGETATION. Composition of Germinated TVheat—Second Stage. Dry. Freed from Ashes. 1 2. Mean. 1. 2 Mean. Carbon...... 0 4456 0 4390 0 4123 0 4569 0 4489 0 4329 Hydrogen.... 0 0583 0 0576 0 0580 0 0593 0 0590 0 0592 Azote.......0 0356 0 0356 0 0356 0 0354 0 0354 0 0354 Oxygen...... 0 4418 0 4441 0 4404 0 4494 0 4557 0 4515 Ashes.......0 0237 0 0237 0 0237 ...... 10000 10000 10000 10000 10000 1000O Recapitulation : Carb. Hydrog. Oxyg. Azote. 1 of wheat, containing.... 0-466 0 058 0 441 0-035 Yields 0 966, containing.. 0 439 0 057 0 334 0 036 Difference........ -0 027 -0 001 -0 007 -f 0 001 In the course of this seeond stage, the wheat in germinating, consequently, lost the same elements as during the first; but the relations between these elements are different. The hydrogen and azote did not vary sensibly ; the quantity of carbon lost was five and a half times as great as that of the oxygen. The loss is, consequently, almost entirely at the cost of the carbon ; there is, nevertheless, a slight loss of oxygen. When we contrast the analysis of the germinat- ed wheat at each period, however, we perceive that in the passage from one to the other, there was a fixation of oxygen. VEGETATION. 91 Ger. gr. Carb. Hyd. Oxyg. Azote. IstPeriod-l of grain )?4 Q 45g 0037 Q.m QQ36 gives............$ 2d Period.......... 0 966 0 439 0057 0 434 0 036 Difference___ -0 008 -0 019 -0 000 -(-0 011-0 000 4. Germination of Wheat—Third Period.—The germination was only stayed when the green parts predominated in the sprung grain. The stems had then a length of from three to five centimetres (1-18 to 1-96 of an English inch). After drying, the several grains were very much wrinkled, al- most empty, and on being crushed, showed scarcely any traces of starch. Composition of Germinated Wheat—Third Stage. 1. 2. Mean. 1. 2. Mean. Carbon...... 0 461 0 457 0 459 0 474 0 470 0 472 Hydrogen.... 0 060 0 060' 0 060 0 061 0 061 0 061 Azote....... 0-041 0041 0041 0042 0 042 0042 Oxygen..... 0 410 0 414 0 412 0 423 0 427 0425 Ashes....... 0 028 0 028 0 028 ...... 1000 1000 1000 1000 1000 1000 Summary : Carb. Hydr. Oxyg. Azote. 1 of wheat, containing.....0 466 0 058 0 441 0 035 In germinating, becomes ? n 397 0 051 0 357 0 036 0 841, containing......) Difference........-0 069 -0 007 -0 084 -(-0 001 To attain this advanced stage of germination, we see that the wheat lost 16 per cent; having yielded to the atmosphere carbon, hydrogen, and oxygen. Analysis does not yet exhibit more than 92 VEGETATION. a very trifling change in the quantity of azote, which has increased rather than diminished. VIII. Principal Chemical Phenomena of Vege- tation.—-It is still by the method of organic analysis that M. Boussingault has demonstrated that plants in full growth always take carbon from the carbonic acid of the air, hydrogen from the water which bathes them, and frequently azote from the air. The soil he used for the growth of his plants, the subjects of experiment, was a siliceous sand, which was first sifted, then kept at a red heat for some time, in order to destroy every trace of or- ganic matter within it. It was then moistened with distilled water, and the seeds sown ; after the interval of a few days, the seeds which did not germinate were removed. The porcelain dishes which contained the sand thus sown were placed in a chamber situated at the extremity of a large garden. The windows of the chamber were kept shut through the whole term of the experiment, but the sunlight entered it freely during the day. In order to gather the harvest, the dishes, with their contents, were dried by means of a gentle heat. The plants were then easily pulled up from among the sand ; and to free their roots from ad- hering particles of sand, they were gently shaken in water. The whole plants were then dried in a stove, and the desiccation was subsequently com- pleted by means of an oil-bath in vacuo. VEGETATION. 93 By determining the weight of the sand, and of the ashes, that of the harvest, dried and freed from ash, was known; this weight was compared with that of the grain sown, deduction being, of course, made of the grain which had not sprung. The sand in which the experiment had been car- ried on was sifted anew, which permitted certain fragments of the plants, and particularly the husks of the grain, to be collected. The sand was elu- triated, and the water evaporated to dryness ; but, with the exception of saline matter, the origin of which could not be accounted for, no residue was obtained of sufficient consequence to be weighed. 1. Growth of Trefoil.—The trefoil which was gathered two months after it had been sown in the sand, was of a fine green color ; but, contrasting it with what it would have been had it been grown in a well-manured soil, it was dwarfish; on an average, the length of the stalks did not exceed 2 inches; its roots, of great tenuity, were a little more than 2 inches long. Composition of the produce obtained. 1. 2. Mean. Carbon - - 0-50S 0-504 0-506 Hydrogen - 0-057 0-058 0-058 Azote - - - 0-047 0-047 0-047 Oxygen - - 0-388 0391 0-389 1000 1000 1000 94 VEGETATION. Summary of the experiment:— Carb. Hvdr. Oxy. Azote. 1 of seed, containing.... 0 508 0 060 0 360 0 072 Yielded a crop of 1 649, )0g34 QQ95 0641 007fl containing.........) Difference.... -f-0 326 4-0 035 -4-1281 -f-0 007 In the course of two months, consequently, the trefoil had acquired azote; the quantity gained is too large to be attributable to any ordinary error in analysis. Further, the seed, or rather, the plant which was its product, acquired carbon, hydrogen, and oxy- gen, from water and from the atmosphere. It is to be observed, that the relations in which the two latter elements occur are those precisely in which they constitute water. The produce after three months had a pretty good appearance, the trefoil having from 2* to 3 inches in height. The warmth of the month of August had brought this crop rapidly forward : a few withered leaves were observed. The largest leaves could be inclosed within a circle about 2 inches in diameter; the length of the roots varied between 2 and about 4 inches, but they were very slender. The produce, dried and powdered, was of a deep green color. VEGETATION. 95 Composition of the produce. 1. 2. Mpan. Carbon - - 0-506 0-508 0-507 Hydrogen - 0 066 0-065 0-066 Azote - - - 0-038 0-038 0-038 Oxygen - - 0-390 0-389 0-3S9 1000 1000 1000 Recapitulation of the experiment: Carb. Hydr. Oxy. Azote. 1 of seed containing...... 0 508 0 060 0 360 0 072 Yielded in produce 2 589, ) j 313 0>m j.007 n 098 containing...........$ Difference........ 4-0-805 +0 111 +0 647 +0 026 In the course of three months, consequently, the seed, become vegetable, acquired about ^th by weight of azote, in addition to that which it con- tained before it was sowed ; the carbon again in- creased in the ratio of 5 to 8; and the hydrogen and oxygen were very nearly doubled ; but here these two substances do not present themselves in the proportions required to form water. The hy- drogen is in excess, and the excess is such that it cannot be ascribed to an error of analysis. From the experiments on trefoil it follows, that, during the germination of the seed, there is no azote fixed ; but, during the growth of the plant, it appears that there is a certain quantity of this element assumed from the air. Amono- the various objections which might be 96 VEGETATION. raised to the precision of the experiments that have now been described, there is only one that appears of any importance, and it has been raised as often as the attempt has been made to fix the weight of the elements which the growing plants take from the air and water: it is that which ascribes a por- tion of the elements acquired by the plants to par- ticles of dust floating in the air. It is impossible to deny the presence of dust in the atmosphere, so that it might be maintained that this influences the result in the manner of manures; and as it is indu- bitable that a part of the dust which floats in the air is of animal origin, it might even be said, until the contrary was demonstrated, that this is the source of the azote which the plants had assimilat- ed during their growth. To remove all doubt upon this point, M. Bous- singault contrived an apparatus in which he could make trefoil germinate and grow, and yet be all the while completely protected from the dust that floats in the air. He still obtained precisely the same results as formerly. In germinating in a close vessel as well as in the open air, trefoil absorbs no notable quantity of azote ; but, during its growth, it gains a very sensible quantity of this element. 2. Wheat grown during the months of Septem- ber and October.—Thirty-seven grains or particles of wheat were sown in sand : they all sprung. The VEGETATION. 97 stems, when the plants were gathered, were from 8 to 10 inches long. They were extremely slen- der, bending under their own weight. Some of the leaves near the bottoms of the stalks were com- pletely discolored; the roots were of excessive length, but thin and capillary. The produce contained Carbon ----- 0-495 Hydrogen - - - - 0-064 Azote- ----- 0-022 Oxygen ----- 0-419 1000 Thus :— Carb. Hydr. Oxy. Azote 1 of wheat containing.... 0 466 0 058 0 441 0 035 Produced 1462, containing 0 724 0 094 0 612 0 032 Difference........+0 258 +0 036 +0 171 -0 003 During the two months of vegetation, therefore, at the sole expense of the air and distilled water, the weio-ht of the wheat increased in the ratio of IJr. The increase took place by an assimilation of carbon,hydrogen, and oxygen; analysis, moreover, shows a slight loss of azote. Wheat grown during the months of August, Sep- tember, and October.—Forty-six grains or particles of wheat were sown in sand : all sprung. When the plants were gathered, the stalks were from 14 to 15 inches long ; the greater number of the lower leaves were yellow : the roots were of considerable 9 98 VEGETATION. length, and by matting together, formed a sort of tissue, which made washing very difficult. Composition of the produce. 1. 2. Mean. Carbon - - 0-4S2 0-482 0-482 Hydrogen - 0057 0-052 0-058 Azote- - - 0-020 0-020 0-020 Oxygen - - 0-441 0439 0440 1000 1000 1000 Thus:— Carb. Hydr. Oxy. Azote. 1 of wheat, containing___ 0 460 0 058 0 441 0 035 Produces 1838, containing 0 880 0 105 0 810 0 037 Difference........+0 420 +0 047 +0 369 +0 002 After three months' vegetation, consequently, the weight of the grain was, so to say, doubled ; the carbon, hydrogen, and oxygen, appear in almost a twofold proportion in the produce. Analysis shows an increase of azote that is altogether insig- nificant. The results obtained with wheat, in reference to germination, were analogous to those come to with trefoil. It appears constant that during this proof there is neither gain nor loss of azote. 3. Growth of Peas.—In cultivating peas under the same conditions, precisely similar results were obtained; but an additional and unexpected fact was also brought to light; it is this: that peas, under the influence of the regimen followed, having no sustenance save air and water, blossomed and brought seed to perfect maturity. VEGETATION. 99 Composition of the Peas, the Subjects of Observation. Ashes included. Ashes deducted. Carbon - - - - 46-5 48-0 H\'drogen - - - 6-1 6 4 Oxygen - - - 401 413 Azote - - - - 4-2 4-3 Ashes - - - - 31 ,, 100-0 1000 Five peas, weighing together about 18 grains, and as nearly as possible of the same weight, were sown on the 9th of May, in baked earth, or clay calcined at a red heat, and then moistened with distilled wTater. On the 16th of July, these peas, which looked extremely well and healthy, were in bloom ; each pea had furnished one stalk, and on each stalk there was one flower. On the 15th of August the pods were ripe; no more water was supplied, and by the end of the month the plants were dry. The length of the stalks varied from 3 feet 3 inches to 5 feet, but they were very slender, and the leaves were not more than one-third the super- ficial size of the leaves of peas grown in a manured soil. The pods were about 1-3 inch long, by from 0-3 to 04 of an inch broad. Four of the pods inclosed two peas each, the fifth contained but one; but this pea was almost twice the size of any of the others. 1-00 VEGETATION. Composition of the produce gathered. Ashes included. Ashes deducted. Carbon- - - - 53-5 54-9 Hydrogen - - - 6'6 6-8 Oxyocn - - - 33-8 34-7 Azote - - - - 3-5 35 Ashes - - - - 2-6 „ 100-0 100-0 Composition of the Stalks and Pods, Ashes deducted. Carbon- ----- 52-8 Hydrogen ----- 62 Oxygen ----- 39.4 Azote ------ 1-6 100-0 Summary of the experiment:— Carb. Hydr. Oxy. Azote. WfoST"»».ar„?„5.SOWn.'?»5'5 ••» •■««> 0 046 Produce, 4441, containing.. 2 376 0 281 1680 0 101 Difference........+1861 +0 215+1.237 +0 055 It results from this experiment that 15| grains of peas gained 511 grains of organic matter in 99 days of vegetation, during the hottest period of the year, and that the weight of azote originally con- tained in the seed was more than doubled in the produce. The rest of the elementary matter, assimilated during the growth of the plant, is not represented exactly by water and carbon ; there is such an ex- VEGETATION. 101 cess of hydrogen as cannot be attributed to an er- ror of analysis. 4. Culture of Trefoil in a Barren Soil.—From a field of trefoil, sown in spring, several plants of the same height were chosen. Three of these, weighing 103 grains in the green state, were put aside and preserved for analysis; three others, which weighed 104 grains, were immediately transplanted to a bed of sand, recently calcined, and moistened with distilled water. This was done on the 28th of May, and the plants were forthwith protected from the dust of the atmosphere. The plants drooped during the first few days, but, by and by, they became remarkably vigorous. At the end of a month the plants had doubled in height; their leaves were of a fine green, and they appeared altogether as strong as those which had been left growing in their original places in the open field. The flowers began to appear about the 8th of July ; on the 15th the flowers were of a fine carnation red, on the 1st of August no more water was supplied and the plants were suffered to die. The roots were found to be very little devel- oped : the extremities were very bushy, but the spindle or tap, which constitutes the body of the trefoil-root, had made no progress. Analysis of the Trefoil before the Experiment.—• The three plants of trefoil reserved afforded— 9* 102 VEGETATION. Carbon.....43 42 Hydrogen - - - - 5 40 Oxygen.....47-43 Azote ----- 3-75 100-00 Composition of the Trefoil, the subject of the Ex- periment in Flower.—Dried in vacuo, at a tempe- rature of 110° C. (266° F.) this trefoil weighed 2-754 grammes (about 41 grains), and yielded,— Carbon - - - - 53 "00 Hydrogen - - - 6*41 Oygen - - - - 38-14 Azote - - - _ 2-45 100-00 Recapitulation:— The trefoil, at the moment of trans- ) 0 884 of a gramme, plantation, freed from ashes, weighed ) or about 14 grains. After 63 days of cultivation, it weighed I 2 264 Sramme?> or S about 33 grains. It had therefore gained in this time X 138,° ?rammps, or ) about 19 grains. Carb. Hydr. Oxy. Azote. Before the experiment, the ) nno* ^ ^o ~ . ~ trefoil contained...... \ ° 384 °'048 °'419 0-933 After the experiment...... 1-200 0-145 0-863 0-056 Difference........+0 816 +0-097 +0 544 +0 023 So that in the course of two months trefoil, living at the sole cost of air and of water, is found, in round numbers, to have tripled the weight of its VEGETATION. 103 elementary matter; the azote, for its part, being very nearly doubled. Growth of Oats in pure Water.—On the 20th of June, three plants were taken from a field of oats, and having been found to weigh 158 grains were set aside for analysis. Four other plants, destined for experiment, and weighing 220 grains, were se- cured from dust, with their roots plunged in distil- led water. About the middle of July the stalks had nearly doubled in length, and, at this time, present- ed the appearance of those which had been left in the open field. At the end of July the plants were in flower. Towards the 10th of August, the grain seemed ripe, and the whole of the plants were dried in the stove. Composition of the young Oat Plants reserved for Analysis. Carbon.....53*0 Hydrogen - - - - 6-8 Oxygen - - - - 36-4 Azote ----- 3-8 100-0 Composition of the ripe Oat Plants, the subject of Experiment. Carbon ----- 48-1 Hydrogen - - * - 6-2 Oxygen.....44-0 Azote - - - - 1'7 100-0 104 VEGETATION. Summary :— The young plants weighed 1-560 grammes, or about 23 grains The plants experimented ) 3 4l8„rammes, or about 52 grains on weighed..........$ Gain, during the experi-) 1158 grammes, or about 16 J ment................$ grains. Carb. Hydr. Oxy. Azote. Before the experiment, the ) 0.g27 Q ]Q6 n 56g 0.059 plants contained......) After 41 days'vegetation.. 1-500 0193 1-373 0-058 Dfference........+9-671 +0-087 +0-804 -0-006 Tn this experiment, analysis shows, that far from there being any gain of azote, there was, on the contrary, a slight loss of this principle. The experiments which have been detailed thus far demonstrate :— 1st. That in germinating, trefoil or clover, and wheat, neither gain nor lose a quantity of azote that is appreciable by analysis. 2d. That during germination these seeds lose carbon, hydrogen, and oxygen; and that the abso- lute loss of each of these elements, as well as the ratios in which the losses take place, vary at differ- ent epochs of the germination. 3d. That during the growth of trefoil in a soil ab- solutely void of organic matter, and under the sole influence of the air and distilled water, this plant assumes carbon, hydrogen, oxygen, and a quantity of azote appreciable to analysis. VEGETATION. 105 4th. That wheat cultivated under precisely the same circumstances also abstracts from the air and from water carbon, hydrogen, and oxygen; but that after the complete growth of the plant analy- sis detects neither gain nor loss of azote. 5th. That peas, planted in a soil absolutely bar- ren and watered with pure water, may attain to complete maturity, passing through all the phases of their natural growth, and bearing flowers and ripe seeds. During this process they fix a large quantity of azote, which they must derive either from the air dissolved in the water which they ab- sorb by their roots, or from the air that surrounds their stalks and leaves. 6th. That trefoil grown at first in a fertile soil, but cultivated subsequently without the concurrence of organic matters, also fixes azote. 7th. That the oat-plant, raised at first in a ma- nured soil, and then placed in the same circumstan- ces as the trefoil, abstracts carbon, hydrogen, and oxygen from the air and water, but assimilates no azote; analysis, on the contrary, showing a slight decrease of this element. From all of which it may be inferred that in cer- tain conditions various plants have the power of de- riving azote from the air. But under what circum- stances, in what state does the azote become fixed in plants 1 These are questions which the present 10S RESPIRATION. state of our knowledge does not allow us to an- swer satisfactorily. Azote, in fact, may enter the organism of plants directly, if their green parts be possessed of the ap- titude to fix it; or the element may be carried into the bodies of the plants dissolved in the water which is aspired by the roots. Finally, it is possi- ble, as some natural philosophers believe, that an infinitely small quantity of ammoniacal vapor constantly exists diffused in the atmosphere.—Ex- tracted from the Memoirs of M. Boussingault, in the Annates de Chemie et de Physique, tomes 57 et 59. IX. Respiration of Man.—From experiments of which I was myself the subject, I find that at each inspiration I introduce about a third of a litre* of air into my lungs; I make from fifteen to seventeen inspirations per minute; the air expired contains from 3 to 5 per cent of carbonic acid ; and it has lost from 4 to 6 per cent of oxygen.f • A litre is 1 760, or very nearly If of an English pint—Ed. t These experiments were performed at Geneva, in 1820, when I was twenty years of age, and were undertaken in con- nection wtth a complete work on Respiration which M Pre- vost and I had then in view. I have since that time quoted them regularly in my courses. It will be seen by and by that as we advance in years the consumption of carbon in- creases.—J. D. RESPIRATION. 107 These data give for each day of 24 hours :— 16 inspirations per "J minute of £ of a i__5 3 litres (about 9 3 pints) of air ex- litre, or 0 533 of j ~ pired per minute. an Eng. pint.. J ---- 318 (57 8 pints) ditto per hour. ---- 763 2 (1387 2 pints) ditto per diem. Assuming that the expired air contains on an av- erage 4 per cent of carbonic acid, we should have, 12 7 litres of carbonic acid per hour. 305 8 ---- per diem. Reduced to weight these data furnish us with: 1661 grammes (about 5 ounces 40 grains) of carbon consumed per diem. 555. grammes of carbon to represent the hydrogen consumed in the same time. 2122 grammes or about 9 ounces of carbon burned 9 ° in 24 hours, which is at the rate of about 9 grammes (or 140 grains) per hour, whether of carbon or its equiva- lent in hydrogen. Some of the older observers estimated the quan- tity of carbon consumed at 340 grammes (or 11 ounces, 1 drachm, 15grains), per diem, which would bring the consumption up to about 14 grammes (or about 3 drachms, 35 grains) per hour. In assuming the consumption at from 10 to 15 grammes (or 2\ to 3f drachms)per hour, we shall be within the limits of the truth. But I hold that the consumption of so many as 15 grammes can only be regarded as the exception, and as applica- 108 RESPIRATION. ble to individuals of great stature, of very ample chest, large eaters, &c. Ten grammes (or 2\ drachms) per hour is probably as near an approxi- mation to the truth as can be made in regard to the generality of men in adult age. The high importance of this question, with which indeed is connected the very serious one of what may be held sufficient sustenance in the shape of food for man, requires that it should be studied with greater attention to accuracy of results, and upon a greater number of individuals than have yet been employed. We are at this time engaged in the study. The experiments which were thus announced in the preceding edition of this Essay have been per- formed by Messrs. Andral and Gavarret with great care. We give an abstract of their paper in this place:— " We have had it in view," say these two phy- siologists, " to determine the quantity of carbonic acid which escapes in a given time from the lungs of man as well in the state of health as in the state of disease. " To accomplish our object we made use of the following apparatus, the first conception of which belongs to Messrs. Dumas and Boussingault. " Through a mask made of impermeable mate- rials, of sufficient capacity to contain an entire RESPIRATION. 109 expiration, and carefully fitted to the face, we es- tablished a current of atmospherical air by means of glass balloons, in which a vacuum had previ- ously been made. It was in this continual current that the subject lived during the course of the ex- periment. The force or rapidity of the current was readily controlled by means of a graduated stop- cock, in such wise that the respiration was always performed freely, without effort either in aspiring or in expiring the air incessantly attracted by the draught of the balloons. Every precaution was further taken to guard against loss of expired gas; and the draught was so regulated that the same portion of air could never be subjected oftener than once to the action of the lungs. " In analysing the gases thus collected, we made use of the processes employed by Messrs. Dumas and Boussingault, with the modifications introduced by M. Leblanc in his work on the analysis of confined air. " Before inquiring to what extent the quantity of carbonic acid exhaled by the lungs may vary in different forms of disease, we felt bound to as- certain by experiments more numerous and conse- quent than any that had yet been undertaken, the quantity eliminated in the physiological or healthy state. Our first endeavor was to make out the influence of the three grand physiological circum- 10 110 RESPIRATION. stances of age, sex, and constitution, upon the ex- halation of carbonic acid by the lungs. It was also important to ascertain the influence of rest and of motion, of watching and of sleep, of fast- ing and repletion, of light and of darkness, &c. " All our experiments were performed as nearly as possible under the same circumstances, on sub- jects in good health, at the same time of the day— viz. between one and two o'clock, at the same in- terval after eating, and in conditions as nearly similar as might be in regard to the quantity and quality of the food, of muscular exertion, of moral state, &c. "And then, to give the greater value to our conclusions, we took care to repeat every experi- ment several times—as often as six times—on the same subject; the agreement in the results was found in every case as great as could be expected in a physiological inquiry. " We collected almost invariably 130 litres (about 217 pints) of gas in each experiment, which lasted between eight and thirteen minutes. The pro- ducts collected were therefore of quantity sufficient on the one hand to render even minimum differ- ences very apparent; and on the other, the trial was continued for a sufficient length of time to ad- mit of a pretty rigorous conclusion from the fact observed, with reference to what would happen in RESPIRATION. Ill the course of an hour or any longer period. We have not, however, made use of our results to cal- culate the quantity of carbonic acid which each individual exhales in the course of twenty-four hours, inasmuch as we are still without the assur- ance that the intensity of the pulmonic function continues the same at every period of the day, and especially of the night. " Let us only further add, that in the statement of our experiments we have generally represented in grammes the quantity of carbon contained in the carbonic acid exhaled, inasmuch as by this means we obtain numbers that are more easily re- membered, and especially because definitively it is the quantity of carbon that is thus burnt which it imports us to know. " Seventy-five experiments were made with all the precautions indicated on seventy-two different subjects, of whom thirty-six were of the male and thirty-six of the female sex. " These experiments satisfied us, that from the age of eight years on to extreme old age, the quantity of carbonic acid exhaled from the lungs in a given time, varies notably according to the age, sex, and constitution of the individual ob- served. " At every age, from eight years upwards, the exhalation of carbonic acid from the lungs is 112 RESPIRATION. greater in males than in females. Here are the differences presented by the two sexes : " In the male the quantity of carbonic acid ex- haled goes on increasing continually from the age of eight to thirty years ; from thirty to forty it is stationary, or even tends to diminish a little ; from forty to fifty the tendency to decrease is more de- cided ; lastly, from fifty to extreme old age, the exhalation of carbonic acid diminishes more and more, until, in men arrived at the last term of ex- istence, it returns to nearly the same amount as it was at ten years of age. " The following numbers indicate the quantity of carbon contained in the carbonic acid exhaled in an hour from the lungs of man at different ages. "A male child, eight years of age, burns 5 grammes (77 grs.) of carbon in an hour; the quantity was found to increase by regular deorrees until the age of fifteen years was attained, when the quantity consumed amounted to 8-7 grammes (133 grs.) " From the age of fifteen, the quantity of carbon consumed increases in the following manner :__ " At sixteen, the consumption is 10-8 gram. (166 grs.) p(T hour ; between eighteen and twenty years, it rises to 11-4 gram. (175 grs.); in the period of life comprised between twenty and thirty years, it remains very constantly at 12-2 gram. RESPIRATION. 113 (187£ grs.) ; and between thirty and forty years, the quantity continues very nearly the same. " From forty to sixty, the measure of carbonic acid exhaled is represented by no more than 10-1 gram. (155 grs.) of carbon ; from sixty to eighty, it is represented by 6-2 gram. (95^ grs.) only; finally, in an old man, aged 102, it was represent- ed by no more than 5-9 gram. (90f grs.) " In following the variations in the quantity of carbonic acid exhaled from the female lungs at different periods of life, we find in the female child, from the age of eight to the period of puberty, that the quantity goes on increasing con- tinually, precisely as in the boy; but it always remains a little less than in him. At the age of puberty, a very-remarkable phenomenon presents itself: it is the sudden cessation of any further increase in the quantity of carbonic acid exhaled from the moment the woman menstruates. Whilst in man the exhalation of carbonic acid augments considerably after the period of puberty, it, on the contrary, continues the same in woman as it was previously to this grand epoch in her life, and so it remains as long as she continues to be regular. When they are in all respects in perfect health, women do not consume more than about 6-4 gram. (98j grs.) of carbon per hour, estimating the con- sumption by the carbonic acid exhaled from the 10* 114 RESPIRATION. lungs ; they are precisely like children of the female sex before puberty; whilst in males the mean of the carbon consumed per hour, which was 7-4 gram, (or 113| grs.), between eight and fifteen years, after this period rises to 11*3 gram. (174 grs.), and so continues to forty. " The period arrives, however, at which females cease to be regular ; and, most remarkable, from this time the quantity of carbonic acid thrown off by the lungs immediately begins to increase; so that in females between thirty-eight and forty- nine years of age who have ceased to be regular, the quantity of carbon which represents that thrown off in the shape of carbonic acid from the lungs, increases from 64 to 8*4 gram. (98| to 129 grs.). But now, as years accumulate, the quantity beirins to lessen, and henceforward follows the same laws as in the male subject, laws from the influence of which females at the critical age ap- peared to have temporarily escaped. 5 Thus, whilst in females between forty and fifty years of age who have ceased to be regular, the quantity of carbonic acid exhaled in the course of an hour indicates 129 grains of. carbon, this mean sinks between fifty and sixty years to 112 grains, and in females between sixty and eighty years, it amounts to no more than 104f grains, a quantity, which is nevertheless higher than we RESPIRATION* 115 found it in women quite regular and only twenty- five years of age. Finally, in a female of eighty- two, we found the consumption of carbon to amount to no more than 92^ grains per hour, a figure which very nearly corresponds with that of the old man of 102. " Another remarkable fact is this: that if, in a young woman, the periodical discharge ceases accidentally at any time, the exhalation of car- bonic acid from the lungs is forthwith suddenly increased, precisely as it is at the critical age. Thus, then, whatever the time of life, the exist- ence of the periodical discharge regularly coin- cides with a diminution in the exhalation of car- bonic acid from the lungs. " If such be the influence of menstruation on the exhalation of carbonic acid from the lungs, it was only natural that we should inquire into the state of affairs when pregnancy came to interfere with the process. We, therefore, instituted obser- vations on four females at different periods of pregnancy, and in them we found that the mean quantity of carbonic consumed amounted, on an average, to about 123 grains per hour, varying in different instances between 115 and 129 grains ; in pregnant women, therefore, the exhalation of carbonic acid obeys the same laws as in those who have passed the critical period of life. 116 RESPIRATION, " In individuals of different ages and different sexes, the general strength of constitution, espe- cially as this is indicated by the development of the muscular system, exerts a notable influence upon the quantity of carbonic acid which is ex- haled from the lungs in a given time; but there is still no violation of the laws already indicated, and age and sex always exert their empire. Thus,. the most robust child never exhales so much car- bonic acid as an adult; but a very sturdy old man may be found burning a quantity of carbon equal to that which is generally consumed at a less ad- vanced age. The most robust female, particularly if she be regular, never exhales so much carbonic acid as the most weakly male of the same age. " The maximum quantity of carbonic acid ex- haled was observed in a young man, twenty-six years of age, and of athletic constitution ; in two successive trials, he burnt upon each occasion at the rate of 217 grains of carbon per hour. In another man, sixty years of age, and whose con- stitution was at least as strong as that of the pre- ceding subject, the quantity of carbonic acid ex- haled indicated a consumption of 209 grains of carbon per hour. In a third, sixty-three years of age, and built like the two former subjects, the consumption was still 190J grains per hour. Lastly, in an old man, who, at ninety-two, pre- RESPIRATION. 117 served a singular degree of energy, and who, in his younger days, had boasted of uncommon mus- cular powers, the quantity consumed was still over 9'8 grammes, or about 151 grains per hour. By way of contrast to this last instance, we may men- tion that the same quantity was indicated in four successive experiments upon a man of only forty- five years of age, whose muscular system was ex- tremely slender, although in other respects he was in the enjoyment of perfect health. " These facts are sufficient to show the influence of individual constitution upon the exhalation of carbonic acid from the lungs ; and they also show to what extent this influence may counterbalance, without, however, destroying that which belongs to age and to sex. " Is it necessary to add, in the face of the va- rious facts that have now been stated, that the weight of the individual, although not entirely without effect, still plays but a very secondary part in connection with the differences noted in regard to the quantity of carbonic acid exhaled 1 To prove this circumstance, it may be enough to say, that a female between twenty and thirty exhales no more carbonic acid than a young girl of twelve years ; that this female eliminates about one half less than a man of the same age,—a difference which very certainly is not explained by any differ- 118 RESPIRATION. ence in the weight of the body ; and, finally, that a man, upwards of a century old, and still in good health, is found throwing off no more carbonic acid than a child ten yeais of age. "And here another and final question-of great importance presents itself: may not the differences in the quantities of carbonic acid exhaled from the lungs in a given time, which have been indicated, be due to a simple difference in the capacity of the chest, in the extent of the respiratory motions, and consequently in the volume of the gases ex- pired 1 The examination of this difficulty would lead us to speak of facts which fall under our pa- thological category; this we shall not do at pre- sent, but merely state, that the limits within which such influences oscillate are extremely restricted, and lay it down as a law that— " The very considerable differences which cor- respond with age, sex, menstruation, and consti- tution, do really indicate a modification in the acti- vity of the forces which in the economy preside over the combustion of carbon. " To sum up, then, we say that— " 1st. The quantity of carbonic acid exhaled by the lungs in a given time, varies by reason of the age, the sex, and the constitution of the subject. " 2d. That the quantity exhaled is modified by RESPIRATION. 119 age, independently of the weight or stature of the individual who is the subject of experiment. " 3d. That in every period of their lives included between eight years and extreme old age, males and females are distinguished by the difference in point of quantity of carbonic acid which is exhaled from their lungs in a given time. All things else being equal, man always exhales more than woman. This difference is particularly well marked between sixteen and forty years—an interval during the whole of which a man gives off nearly twice as much carbonic acid from his lungs as a woman. " 4th. In man, the quantity of carbonic acid exhaled goes on increasing incessantly from eight to thirty years of age, and this continual increase becomes suddenly very great at the period of puberty. From thirty years, the exhalation of car- bonic acid begins to decrease, and the decrement takes place by degrees, which are by so much the more strongly marked as man approaches to ex- treme age, and finally goes so far, that at length the exhalation of carbonic acid from the lungs returns to that which it was about the tenth year. " 5th. In woman, the exhalation of carbonic acid increases from infancy and through youth up to puberty, according to the same laws as in man; but at puberty, and simultaneously with the appearance of the periodical discharge, the exhalation suffers 120 RESPIRATION. an arrest, and continues stationary at the point to which it had attained, so long as this discharge per- sists. On its cessation, however, the exhalation of carbonic acid from the lungs increases in a very decided manner; and then it decreases in proportion as woman advances in years, precisely as in men. " 6th. The exhalation of carbonic acid from the lungs is increased during the whole term of preg- nancy, attaining temporarily to the same amount as in women who have passed the critical age. "7th. The quantity of carbonic acid exhaled from the lungs is at all ages by so much greater as the constitution is stronger and the muscular system more highly developed." X. Exhalation of Azote by Animals. When respiration is studied in the human subject, it is extremely difficult to determine the exhalation of azote ; we do not know the precise quantity of air inspired, and if we seek to ascertain it by an ana- lysis of the expired air, we perceive that the exha- lation of azote is confounded with the disappear- ance of the oxygen which corresponds with the quantity of hydrogen that is burned. Thus, if we analyse a measure of air in which a man has breathed, we shall find, for example : Azote ------ 798 Carbonic acid - - - - 16 ) Oxygen.....186 \ 202 1000 RESPIRATION. 121 The sum of the carbonic acid and oxygen ought to produce 202; it only represents 200. Now the difference can be explained either in supposing that six parts of oxygen have disappeared to form water, or that thirty parts of azote have been dis- engaged. It is impossible to know precisely what has happened, and to say in what proportion each of these causes has contributed to the final result. The exhalation of azote can only be determined by making an animal respire in a known quantity of air. This was the course pursued by Messrs. Dulong and Despretz in their experiments. Now, these experiments exhibit a notable and constant exhalation of azote ; for in seventeen experiments, M. Dulong ascertained, upon fourteen occasions, a decided exhalation of azote; in the other two there was neither absorption nor exhalation bf this principle. On the other hand, M. Boussingault has shown, that there ought to be an exhalation of azote from the luno-s, inasmuch as the whole of the azote con- sumed as food does not re-appear either in the urine or the excrements. It may therefore be affirmed, that animals do not take azote from the air; all carefully conducted experiments, on the contrary, show that they rather exhale it. Such is, in fact, the opinion adopted by Berthol- 11 122 EXCRETION OF UREA. let, Nysten, Dulong, and Despretz, from their indi- vidual experiments upon the respiration of animals. M. Despretz has, indeed, insisted upon this conclu- sion in a very particular manner; he even makes it a general law, inasmuch as he observed an ex- halation of azote in at least two hundred experi- ments. As there is some reason to suspect that the quantity of azote exhaled from the lungs has been exaggerated, new experiments upon the subject seem desirable. XI. Excretion of Urea.—I have assumed the fol- lowing as the composition of urea :— 2 atoms of carbon - - - 12 20-0 2 — oxygen - - - 16 26-6 4 — azote - - - - 23 46-6 4 — hydrogen - - 4 6-6 60 100-0 In examining the effect which the animal sub- stances that accompany the urea in the urine pro- duce upon it, we find that, becoming altered or modified by exposure to the air, they turn to true ferments ; and that, under their influence, the urea fixes water in such proportions as convert it into carbonate of ammonia. ANIMAL HEAT. 123 1 atom of urea = C202 Az4H4 2 atoms of woter= 02 H4 2 atoms of carbonate of ammonia=C2 O4 Az4 H6 Thus the constitution of urine is such, that the whole of the urea excreted by animals through the channel of the kidney, must be speedily turned into carbonate of ammonia. By the side of urea we find two other excretions of the same order—the uric and the hippuric acids. Uric acid contains— 10 atoms of carbon - 60 35-71 4 — hydrogen - - 4 2-37 8 — azote - - - 56 33-33 6 — oxygen - ■ - 48 28-59 168 100-00 Crystallised hippuric acid contains:— 18 atoms of carbon - ■ - 108 60.33 9 — hydrogen 9 50-3 2 — azote - • 14 7-82 5 — oxygen - ■ ■ 48 26-82 177 10000 XII. Heat of Animals and of Vegetables.—The animal heat was considered by Laplace and Lavoi- sier as entirely due to the slow combustion which 124 ANIMAL HEAT. goes on in the blood under the influence of respi- ration. We regard this view as the expression of the truth, although some recent experiments call in question its accuracy. In their experiments, having for object the mea- sure of animal heat in its relations with respiration, Messrs. Dulong and Despretz employed— 1st. A water calorimeter, in which the animal was placed; 2d, Two gasometers, contrived, the one to furnish, the other to receive, the air necessary to respiration. Of 100 parts of heat absorbed by the calori- meter, M. Dulong found when he made use of water that the combustion of carbon or of hydrogen in the process of respiration accounted for 75 or 80 parts. The remaining 20 or 25 parts he ascribed to a cause unknown. M. Despretz, who operated with mercury, col- lected the carbonic acid thrown off in respiration more completely than M. Dulong had done, and of 100 parts of heat collected by the calorimeter, he found from 80 to 90 parts due to respiration. We must be convinced that the portion of heat absorbed by the water of the calorimeter, which exceeds that represented by the respiration, is due, in principal part, to a true cooling of the animal, when we observe that those animals whose proper temperature is the highest, and which cool most ANIMAL HEAT. 125 readily, are precisely those which present the greatest excesses. The experiments of M. Edwards have, in fact, shown that young animals lose a por- tion of their heat much more readily than adult animals of the same species, and it is necessary to remember this conclusion, in order to explain cer- tain apparent anomalies which are encountered in such experiments. Here is the table which M. Despretz has pub- lished of his experiments, experiments which, in other respects, deserve every confidence from the care with which they were performed : Caloric produced Caloric collected by by Respiration. the Calorimeter. Vnnno- f 2 little PuPPies °f animals < 5 Weeks........ 10° I35 ammais. [^ i bitch of 8 months 100 135 Temnerature f 4 magpies........ 100 133 lemperature . 4 ow]g .......... of the animal . ... . . ,„„ ,__ from 42° t0 An *d Jilt great owl 100 29 .-o r /./yyo i 3 adult pisreons ... 100 126 ^n»L, | Adult duck....... 100 126 loiirfr.j ^ Adult fowl (male j.. 100 125 Ditto, from ") 38° to 39° C. i Cat 2 years old ... 100 123 (100° to 103° f Bitch 2 years old.. 100 123 F-) J Ditto, from /'Male rabbit...... 100 115 35° to 36° C. ^ 3 adult Guinea-pigs 100 112 (95° to 97° F.) L Adult doe rabbit .. 100 110 This table shows clearly that the excess of heat collected by the calorimeter is by so much greater as the animal is younger, and as its proper tempera- ture is higher. 11* 126 SOURCE OF MINERAL SUBSTANCES. In other words, the heat which the animal lost to the water which surrounded it, renders a satisfac- tory account of the apparent excess of heat observed in these experiments. It is not proved, therefore, that there is any source of heat in animals, save respiration. The theory of Laplace and Lavoisier, in conclu- sion, wrhich ascribes the whole of the heat produced by animals t their respiration, must still be held as the most probable. XIII. Of the Source of the Mineral Substances which are met with in Organized Beings.—It has often been subject of debate, whether or not plants create any mineral substances in the course of their growth, and whether or not animals on their side produce them during their lives. With regard to vegetables, the experiments of M. Laissaigne prove indisputably that they have no faculty of the kind. And with reference to animals, so far back as the year 1822, I made some experiments in concert with my friend, Dr. Prevost, of Geneva, which lead to the same conclusion. Eight fresh eggs, weighing together 428'55 grammes, yielded 40-10 grammes of ashes. Nine incubated eggs, at the point of hatching, DIGESTION. 127 weighing together 426-53 grammes, yielded 51-87 grammes of ashes. Twelve fresh eggs, weighing together 676'37 grammes, lost, during the period of incubation, a quantity equal to 92-75 grammes. The following conclusions have been deduced with regard to the comparative composition of fresh eggs and eggs ready to hatch :— Fresh E<*es Eggs at the point *resn i,ggs. 0f hatching. Mineral substances - - 9-3 9.4 Organic substances - - 23-8 21.2 Water ------ 66-9 55-6 Loss during incubation - . . 13-8 100-0 100.0 Whence it follows, that there is an actual des- truction of organic matter during the development of the chick, and that there is no production of mineral or inorganic substance. XIV. Theory of Digestion.—We have recognized two distinct digestions: 1st, That of soluble articles, which takes place in the stomach ; 2d, That of fatty or insoluble substances, which must take place in the intestinal canal. M. Sandras and Bouchardat express themselves to the following effect on this subject:— 1st. In digestion the function of the stomach con- 12S DIGESTION. sists, with reference to albuminous substances— fibrine, albumen, caseine, gluten, in dissolving them by means of the hydrochloric acid. 2d. This acid suffices, when exceedingly diluted (| part to the 1000?—dilue au demi-milli?me), for the solution of the substances cited, so long as they are raw. If they have been boiled, or otherwise exposed to a high temperature, the dilute hydro- chloric acid no longer suffices for their solution in our glass vessels; and as they are certainly dissolved in the living stomach, we must admit that some- thing more than a simple digestion in dilute hy- drochloric acid there takes place; only the presence of hydrochloric acid appears to us to be at all times indispensable. 3d. In regard to albuminous substances, diges- tion and absorption are performed almost exclu- sively in the stomach, the rest of the alimentary canal showing almost no trace of this solution in its contents, although it was found very abundant in the stomach. 4th. It is in the stomach, also, that the solution of fecula is accomplished. In the ordinary state this principle does not appear to us to be changed into sugar; neither do we hold it demonstrated that it passes into the state of soluble starch or dextrine; we look upon its conversion into lactic acid as ascertained. DIGESTION. 129 5th. The absorption of this portion of the food has appeared to us less exclusively confined to the stomach than that of the albuminous matters which are dissolved there. This is in accordance with the particular characters of the intestines in non- carnivorous animals. 6th. Fat is not attacked in the stomach ; it pass- es into the duodenum in the state of emulsion, to which it is brought by means of the alkalis fur- nished by the liver and pancreas. This emulsion is found in abundance, through the whole intestinal tracts. 7th. The chyle appeared to us similar in ani- mals which were killed fasting, and in those that were killed shortly after being fed with albuminous substances and fecula. It never showed any mark- ed difference, save in those that we fed with fatty substances, which were found in it in considerable proportion. The action of water sharpened with hydrochlo- ric acid, to which a few drops of rennet were add- ed, was studied by M. Cahours and myself; and as the results we obtained are rather curious, I shall briefly mention them here. When some fibrine, which has been washed, freed from grease and dried, is thrown into a flask, containing water, acidulated with hydrochloric acid, in the proportion of about 19 grains of 130 DIGESTION. acid to If pints of water, the substance is observed to swell, to become transparent, and then to ac- quire at least ten times its original bulk.* After a considerable interval of time, a part of the fibrine generally dissolves ; but in some cases no solution whatever occurs. When, however, a few drops of rennet are added to the acid menstruum, solution is found to take place in from twenty to twenty- four hours, if the temperature be maintained at from 10° to 15° C. (50° to 60° F.), and in from four to five hours, if the temperature have been kept at between 35° and 40° C. (65° and 104° F.) The filtered fluid is colorless, transparent, and bears a strong resemblance to an albuminous liquid, such as serum. The addition of strong or dilute hydrochloric, nitric or sulphuric acid, determines the formation of an abundant white flocculent pre- cipitate : a solution of alum has the same effect. Evaporated in vacuo over sulphuric acid, the liquid leaves a substance of a yellowish white color, which resembles dried albumen. This substance dissolves readily in warm water, and the solution is not coagulated by heat. Coagulated albumen behaves in the same way with the acidulated liquor to which a few drops of rennet, or better, of gastric juice, have been added; but the solution is effected much more slowly. * The analysis of this product satisfied us that the fibrine had suffered no change in its composition. DIGESTION. 131 If the acidulated liquor be employed alone, the same results can be obtained by carrying the tem- perature to 100° C. (212° F.) We have analysed the various products obtained, and have discovered numbers which seem to ap- proximate this substance with chondrine in point of composition; but it differs from chondrine in its properties. Chondrine, however, treated with water slightly acidulated with hydrochloric acid, furnishes a pro- duct which entirely resembles the substance just mentioned. Our analysis satisfies us that the substance which arises under such circumstances may be considered as albumine, which has fixed water. These analyses, in fact, afford this mean:— Carbon, - - - 50-8 Hvdrogen, - - 71 Azote, - - - 15-0 Oxygen, &c. - 27-1 100-0 Whence the following formula may be de- duced :— C 48 H x Az12 O 15 + 4H 2 O. C48 - - - - 288 51-06 H40 - - - - 40 7-09 Az12 - - - 84 14-88 Qi9 _ - - - 152 26.97 564 100-00 132 FORMATION OF FAT. Formation of Fatty Substances.—I have agreed with Messrs. Boussingault and Payen, that oils or fats are produced by vegetables; that they pass ready formed from them into the bodies of animals, and that there they may either be burnt immediate- ly, in order to supply the heat which the animal requires, or that they may be laid up in the tissues more or less modified, to serve as a reserve for re- spiration. With a view to verify this idea, we in- stituted many experiments, which all led us to re- coo-nize, in the food of the herbivorous animals subjected to experiment, quantities of fatty matter superior to those found in the milk of the milch- cows, for example, or stored up in the tissues of the ox put up to fatten. By keeping account of the fatty matter contained in the dung, and adding it to the quantity fixed, the sum obtained is still infe- rior to the quantity of fat which analysis discovers in the food of the animal. With these facts before us, it appeared to us natural to admit that animals assimilated directly the fatty substances of vegeta- bles without modifying them at all, or modifying them but little. M. Liebig, again, has published some specula- tions on this subject. In his opinion, fatty mat- ters are formed in the herbivora at the cost of their food. He conceives that the neutral non-azotised substances,—starch, gum, sugar, by the elimina- FORMATION OF FAT. 133 tion of a certain quantity of oxygen, may be con- verted into fat in the blood itself, under the influ- ence of the most intimate forces of animal life. We have not admitted that such conversions were indicated in reference to azotized substances; and with regard to starch and sugar, we have held that, if they undergo such a change, it must be in virtue of a true fermentation analogous to that whence is derived the fuesel oil, or fetid oil of po- tatoe spirit, which M. Stas and I have succeeded in changing into phocenic acid. Messrs. Pelouze and Gelis have since found that sugar, fermenting in a particular manner under the influence of cheese, produces butyric acid. Since the publica- tion of these researches, M. Edwards and I have observed, as did Hubert half a century ago, that bees fed with sugar alone had still the power of producing wax. If further experience shows that animals do ac- tually possess the faculty of engendering fatty mat- ters from sugar as bees produce wax from the same substance, we shall have to conclude that there is another point of resemblance between the fruits of plants and animals properly so called. In the same way as we see that fruit is the seat of certain metamorphoses, in which sugar disappears and becomes changed into fatty matter; so will animals be found laying up in reserve with the 12 134 FORMATION OF FAT. same purpose and by the same means, under t-Lc form of fat, the sugar which they have not con- sumed in their respiration. The decomposition of sugar and its return to the state of carbonic acid and water would thus be ac- complished by two very different means: 1st. A fermentation which, in fruit, and perhaps in some animals, converts it into carbonic acid and fatty mat- ter, insoluble in water ; 2d. A total combustion of the fatty matter so produced, whence result car- bonic acid and water. The formation of fatty principles and their de- position in certain tissues would, therefore, consti- tute a phenomenon intermediate to the creation of organic products, which take place by the respira- tion of plants, and their destruction, which is effect- ed by the respiration of animals. At all events, it is at this time certain that her- bivorous animals make use of all the fatty substan- ces which plants contain, and that these substan- ces are more abundant than had been supposed. It is almost certain, also, that carnivorous animals do not produce any fat, so that the neutral azotised substances are necessarily excluded from the num- ber of bodies capable of being converted into fat by the act of digestion. To these general statements it must be added, that Messrs. Bouchardat and Sandras, on the one FORMATION OF FAT. 135 hand, and Messrs. Delafond and Gruby on the oth- er, have found, by means the most unquestionable, that the fatty substances of our food pass by the in- testinal villi into the lacteal vessels, and constitute the matter wdiich gives the chyle its opacity and white color. When the food contains no fatty matter, the chyle is scarcely opalescent; it has none of its ordinary milkiness. In digestion, therefore, there is an apparatus,— and this is the most characteristic element in this function—which, as we have seen, possesses the special faculty of absorbing fatty matters reduced to the state of emulsion, suffering very little to escape it where the function is vigorous. There is, consequently, no reason to feel surprise that the fatty elements in the food of herbivorous animals, however small their quantity in appear- ance, should be almost completely assimilated in digestion. The principal facts and conclusions which have been announced in this discourse, began to take shape in our mind so far back as the year 1837; but, convinced that it was necessary to build upon reiterated experience previously to coining before the public, we thought fit to expose them gradually, and only in proportion as it became possible to jus- tify them by positive facts. 136 HISTORICAL DATA. We have not been able, to our great regret, to persevere in this strict path. A publication of our personal opinions, premature in certain respects, at least, appeared to us to have become quite neces- sary in 1841; for we saw ourselves exposed to the risk of losing all our rights. This necessity, which was a subject of much re- gret with us, will serve as our apology for having laid down certain propositions before having per- formed the experiments which would have served to control them. The historical notes which fol- low, will, in other respects, complete the references to the authorities upon which we have leaned in adopting the opinions we have advocated. Organic chemistry has now entered upon a course of exploration, in which, balance in hand, it seeks to afford testimony to the truth of certain general views having reference to the physics of the globe. To whom does the discovery of these views be- long ? To whom shall be assigned the first use of the balance as a general means of investigation in studying the phenomena of life 1 The answer to these queries is easy :— Respiration and Animal Heat.—In the chemis- try of Lavoisier we find the following passage :— " This is not the place to enter into any detail in regard to organized beings. It is from design that I have passed them over in this work, and it is this RESPIRATION. 137 that has prevented me from speaking of the phe- nomena of respiration, sanguification, and animal heat. " I shall return some day to these subjects."* This he did in fact; and in these terms, some few days only before his deplorable end, did he an- nounce the general result of his experiments, so well combined and so precise:— " Setting out from the knowledge we possess, and confining ourselves to such simple ideas as every one may appreciate, we shall say, in the first place, that respiration is nothing more than a slow combustion of carbon and hydrogen, resembling in all respects that which takes place in a lamp or candle which burns; and that, in this point of view, animals which respire are true combustible bodies which burn and consume. " In respiration, as in combustion, it is the air of the atmosphere which furnishes the oxygen and the caloric ; but, as in respiration, it is the substance of the animal itself, as it is the blood which sup- plies the combustible matter; did not animals re- pair habitually by their food the loss they sustained by respiration, the lamp would soon be void of oil, and the animal would die as a lamp goes out when its oil is consumed. " The proofs of this identity of effect between Elemens de Chimie. 12* loo 1I1T0RICAL DATA. respiration and the combustion of oil in a lamp, flow immediately from experiment. The air, in fact, which has served for respiration, no longer contains its original quantity of oxygen; it con- tains not only a quantity of carbonic acid gas, but much more water than it did before it was taken into the lungs. Now, as vital air can only become converted into carbonic acid gas by an addition of carbon; as it cannot be converted into water with- out an addition of hydrogen; as this two-fold com- bination cannot take place without the vital air losing a portion of its specific caloric, it follows, that the effect of respiration is to extract a portion of carbon and of hydrogen from the blood; and, in the place of this, to leave a portion of its spe- cific heat, which, during the circulation of the blood, is distributed to all parts of the body, and there maintains that almost invariable temperature which is observed in every animal that breathes. " We might imagine that this analogy between respiration and combustion had not escaped the poets, or rather the philosophers, of antiquity, of whom the poets were the organs and interpreters. This fire, stolen from heaven—this torch of Prome- theus, does not only present us with an ingenious and poetic idea ; it is much rather a faithful picture of the operations of nature. We may therefore say, with the ancients, that the torch of life is light- RESPIRATION. 139 ed when the child begins to breathe,"and that it is not extinguished until death. " In reviewing an illustration so happy, we are almost tempted to believe, that the ancients had, in fact, penetrated more deeply than is generally imagined into the sanctuary of the sciences, and that their fables, as some writers have maintained, are but allegories under which they have concealed important truths in general physics and in medi- cine."* It was not, therefore, without very sufficient rea- son that we, at the end of our discourse, ascribed to Lavoisier the discovery of the route which physi- ology now treads with so much security in matters of detail, but of which our great chemist had al- ready seen the general course with his penetrating glance. This restitution is not, however, a matter of cir- cumstance. To prove this, it will suffice if I recall the following words delivered in 1837, three years before anything of recent date had been written on the relations that connect the air of the atmosphere and organized beings so intimately :— " We begin to understand, it was said, the se- duction which Lavoisier exerted on his age, when we see that, in attaching himself with singular per- severance to the study of the air, of water, of car- * Mtimoires, torn. iii. 140 HISTORICAL DATA. bonic acid and of carbon, he had actually made choice of the four bodies,—discriminating them with wonderful sagacity from the host of others,— which serve especially for the accomplishment of all the phenomena in the life of plants and animals. " Not only do these bodies play an important part in crude nature in the formation and alteration of the products that constitute the crust of our globe, but it may be boldly asserted that without them— without the wonderful relations they manifest, life would never have appeared upon the face of the earth ; it would not have met with the plastic material which it fashions with so much art and facility. " These are the four bodies, in fact, which, be- coming animated at the fire of the sun, the true torch of Prometheus, approve themselves upon the earth the eternal agents of organization, of sensa- tion, of motion, and of thought."* " If nothing comes between me and my pur- pose," adds the writei, " I mean to devote a por- tion of my course next season to the simplest and most general explanation of what passes in organized bodies during their life and after their death, takino- my stand upon the results of physiology and those of organic chemistry. I do not fear to say that * Dumas, Lecons de Philosoyhie Chimique, p. 100. Paris, 1837. USE OF THE BALANCE. 141 here, too, we shall discover admirable laws—sim- ple laws—harmonies worthy of the whole attention of enlightened minds."* Use of the Balance—Fixation of Carbon and Hydrogen by Plants.—At the very same time, M. Boussingault began on his part the long series of in- quiries to which he has dedicated himself for seve- ral years. These inquiries he imparted to the In- stitute in more than one successive memoir, which were received by agriculturalists at first with many misgivings, and which led to the following report made to the Academy of Sciences in 1839 by M» Dumas. " Messrs. Thenard, Pelouze, and myself, have been charged by the Academy to render an ac- count of the last memoir of M. Boussingault upon the chemical phenomena of vegetation and the the- ory Of rotation. " It is long since the author communicated the principal facts of this memoir to your Reporter, and the Academy will understand that this circumstance ought to be known, for it proves that M. Buos- singault proceeds to the researches, the results of which he has communicated to the Academy for some time past, according to a system of ideas attained to a long time ago. " In the rank of the conquests of modern philoso- • Dumas, Lecons de Philosophic Chimique, p. 420. 142 HISTORICAL DATA. phy must be placed those admirable laws which have fixed the parts severally played by water, air, and carbonic acid, in the development of plants and animals. Modern chemistry alone was in a condition to discover this series of marvellous re- actions, the equilibrium of which assures the sta- bility in point of composition of the atmosphere, and consequently of plants, and of animals, upon the surface of the earth. " All that was known of this subject, however, had been learned by means of procedures employ- ed of old, and without the use of the balance, the only method, nevertheless, which can, by possibili- ty, lead to results of precision sufficient to dissi- pate every doubt. " But the character of the researches of M. Bous- singault is this : he has introduced the use of the balance into the study of the questions of general physiology which engaged his attention; he has striven to find an equation for each of them; and, placing on one hand all the substances employed, on the other all the matters produced, he is enabled to render an exact amount of the changes expe- rienced by each element during the course of every experiment. " Thus, when M. Boussingault would discover the influence of water, or of air, upon a plant, he places it in a closed vessel or chamber, in relation CSE OF THE BALANCE. 143 with these two bodies in a state of freedom from impurity, and he makes the elementary analysis of the plant before and after its introduction into the apparatus, which protects it against every foreign influence. " In this way he has discovered that certain plants abstract azote largely from the air, whilst others take none; a very extraordinary fact,but sino-ularly well calculated to shed light upon the part which manures play in rural economy. " He has further ascertained that plants, inde- pendently of the water which they fix, also appropri- ate hydrogen ; that is to say, he has determined a de- composition of water in the act of vegetation, in the same way as the decomposition of carbonic acid had already been discovered. " Finally, he has verified the fixation of carbon derived from the carbonic acid of the air, having here confined himself to controlling by the balance, a fact which had been detected by other means. " From the phenomena which take place when a plant, restricted to air and water by way of nour- ishment, veo-etates under a bell-glass, to those that occur when the plant grows in the open field, there is a difficult step to take ; the question involved is of no less significance than to determine the part played by manures. The author has essayed the solution of this de- 144 HISTORICAL DATA. licate question by the general method already in- dicated. He forms an equation, the first member of which includes the elements of manure, those of the seed, and a third term, the value of Avhich is unknown; whilst the second member comprises the elements of the crop or produce. He then inquires what the air, or the water, must have furnished to complete the equilibrium ; for the produce generally greatly exceeds ihe ele- ments of the seed and manure in weight. The third term, of unknown value, represents what has been supplied by the water or the air ; that is to say, by those manures, or aliments of plants which cost the farmer nothing; and all things else being equal, it is then easy to judge, according to its rise or fall, whether the crop have been favorable or burthensome. The author, therefore, weighed the dung and the seed, and then, by varied analyses, he sought to render an account of the quantity and nature of the elements which these two bodies included. ' On the other side, he likewise weighed the whole of the produce collected, and analysed it exactly. He then arranged the results in such a way as to confront the various common elements, and came to the following conclusions :__ USE OF THE BALANCE. 145 As a general rule, the crop contains twice as much carbon as the seed or the manure. In a general way, also, the crop contains twice as much hydrogen as the seed and manure, a por- tion of the hydrogen having been fixed indepen- dently of the fixation of water. In genera], further, the crop contains about one- half more of azote than the seed or the manure could have furnished to the plant. But when the Jerusalem artichoke is studied, the culture of which is so extensively practised in Alsace, where the author holds a large farm, it is found that the quantity of carbon is quintupled, and that of azote doubled, so that it may be said that of all the crops tried by the author, the Jeru- salem artichoke is the most productive, inasmuch as it takes the largest quantity of carbon and of azote from the elements of the air, pabula that cost nothing. On the other hand, the cultivation of wheat upon a manured fallow is the least pro- ductive, inasmuch as in the crop little or no larger a quantity of azote is discovered, than was already contained in the seed and manure expended. It must be perfectly understood, that if the au- thor admits that all the elements of the manure, or of the seed, pass into the produce, it is only to place himself in the case in which their effect would be carried to its maximum; the influence 13 146 HISTORICAL DATA. which he ascribes to the air and to water is, there- fore, reckoned at the lowest amount; but it is still very great, as must be apparent, when it is seen that the Jerusalem artichoke upon a hectare (2*473 acres) of land takes more than 13,000 kilogrammes of carbon, and 130 kilogrammes of azote.* The experiments of M. Boussingault, therefore, embracing, as they do, the action of vegetables on the air, on water, and on manures, and that of ani- mals upon food and air, tend to base, on accurate analysis, the true doctrine of the statistics of animals and vegetables—one, and not one of the least important or interesting of the services which the process of organic analysis, discovered more than thirty years ago by Gay-Lussac and Thenard, shall have rendered. These researches of M. Boussingault accord with the known fact, that plants decompose carbonic acid, appropriating its carbon, and returning its oxygen to the air, whilst animals convert anew this carbon into carbonic acid; That plants also decompose water, fixing its hydrogen, and unquestionably restoring its oxygen to the air, whilst herbivorous animals convert anew this hydrogen into water ; That certain plants appropriate the azote of the * A kilogramme being equal to 2-205 lbs. avoirdupois, the equivalent English weights are about 28,000 lbs. carbon, and 286 lbs. azote. ' USE OF THE BALANCE. 147 air, whilst others derive none of this element from this source. Of these consequences, the first had been al- ready acquired for science ; but the second and the third are new, and of the very highest importance.* By the side of this Report, and bearing the same date, the Comptes-Rendus, or Account of Proceedings of the Academy of Sciences, contains another upon a memoir of M. Payen. The re- porter there makes it appear, that from the analy- ses of woody matters performed by M. Payen, it is imperative on us to admit a cellulose in every wood, formed of carbon and of water, and an incrusting matter in which hydrogen is in excess. He con- cludes from this, that water must have been de- composed to furnish the hydrogen. A discussion having arisen in the Academy on the occasion of receiving these reports, and on the election of M. Boussingault, M. Dumas, giving utterance to the thoughts of the committee, showed that the whole of these late researches led neces- sarily to the conclusion, that if animals are appa- ratuses of combustion, plants, on their part, are as certainly a reducing apparatus. In his opinion, M. Boussingault, in proving that plants decompose water had raised the particular fact of the decom- » Comptes-Rendus de l'Academie des Sciences, torn. viii. p. 54. 1839. 148 HISTORICAL DATA. position of carbonic acid by the green leaves of vegetables, into a general theorem of terrestrial physics. Sennebier, therefore, had shown that plants de- compose carbonic acid to fix the carbon. ' M. Boussingault has shown that they decompose water to fix its hydrogen. Lastly, a committee of the Academy of Sciences in 1839 contrasted the reducing office of plants with the destructive action of animals; In showing that animals burn carbon to form carbonic acid, and that they burn hydrogen to form water; Whilst plants decompose carbonic acid to seize upon its carbon, and decompose water to seize on its hydrogen. It follows incontestably from these data, that, previously to the year 1839, the general physical principles upon which, in our discourse on the balance of organic nature, we summed up the parts severally played by vegetables, and by animals in the economy of nature, had already been laid down and discussed in printed works. Source of the Azote of Plants.—Whilst in the preceding pages we have spoken continually of certain plants taking azote from the air, and of others deriving it from manures, there is no posi- SOURCE OF AZOTE. 149 tive mention of ammoniacal compounds having any essential part to play in this phenomenon. The reason is simple : it is, that though we saw ammoniacal compounds play the pait of powerful manures, it was impossible to affirm that the azote of the air takes this form before becoming fixed in the substance of plants. In presence of the Aca- demy we should, therefore, have had nothing to offer beyond an opinion upon the subject. But if we divide the question it becomes perfectly clear. M. Boussingault shows us that certain plants fix the azote of the air. It is not known whether this azote passes into the state of ammonia before be- coming fixed; ulterior experiments can alone de- termine the point. What renders it probable that it does, is the fact that ammoniacal salts certainly play an important part in the manures of which they form a constitu- ent. Let us see, then, to whom belongs the dis- covery of this duty, or, at all events, who first en- deavored to give a practical demonstration of the fact. In a journey which he took into Alsace, in 1836, in the course of which he visited the beauti- ful manufactory of Bouxwiller, in company with M. Peligot, M. Dumas received the following com- munication from M. Schattenmann :— " Ammoniacal salts form very energetic manures. 13* 150 HISTORICAL DATA. In Switzerland it is the practice to drench the dungheaps, and to saturate the liquor obtained with sulphate of iron or sulphuric acid, by which meai.s a liquid manure of great potency is obtained. The sulphate of ammonia in solution, distributed over a meadow with a watering-pot, enables us to repeat the celebrated experiment of Franklin." Since this time, M. Dumas has always cited M. Schattenmann in his Course, as having discovered the part which ammonia plays in vegetation. But here is an abstract of a letter from this ingenious manufacturer on the subject:— " I esteem it a proof of your kindness that you do me the honor to quote me upon various occa- sions in treating of the action of ammonia upon vegetation. " The treatment of manures is still greatly neg- lected in France, and even in Alsace, where agri- culture is nevertheless very far advanced. For a long time past the urine of the stable has been made use of in Switzerland; there they are in the habit of exhausting dunghills with water and col- lecting the liquor in ditches, in which, after fer- mentation, the ammonia is saturated and converted into sulphate of ammonia by means of sulphate of iron, sulphate of lime, or oil of vitriol. The liquor thus prepared, distributed over the fields, produces a luxuriant vegetation, which must be mainly as- SOURCE OF AZOTE. 151 cribed to the sulphate of ammonia, which is not volatile like the carbonate, and is not dissipated and lost to the proprietor by the action of heat. Dung, like urine, contains ammonia, which it is of import to preserve, but which, under the usual modes of procedure, is generally lost. " Horse-dung is held to be vastly inferior to that of horned cattle; but this appears to be emuely owing to the method of treating it, which in Al- sace, Lorraine, and throughout France generally, consists sometimes in throwing it into a pit, where it is liable to be drowned with water, sometimes in heaping it up in a hillock, either leaving it dry, or watering it insufficiently. The prejudiced notion that horse-dung does not make good manure unless it be turned and mixed, leads to its being stirred once or twice at least. Now, the dung which is immersed in water does not ferment, and the straw does not undergo decomposition ; and that, on the contrary, which is heaped up lightly, and is not sufficiently watered, heats up to the point that it moulds; the ammonia which has been formed is dissipated, and the most energetic portion of the manure is lost. The manure that remains is, in fact, light and little substantial, and vastly inferior to thaUlerived from the dung of oxen and kine, which, as being naturally moist and fat, is little disposed to heat and perish. 152 HISTORICAL DATA. '• For my own part, I have always treated horse- dung with perfect success, upon a plan altogether different from that which is generally practised. I had a square shallow pit dug, 400 metres super- ficial measure (about 437£ yards), but divided into two compartments of 200 metres each. This pit is an inclined plane, sloping towards the middle, so that the liquid which oozes from the dung-hill col- lects in a reservoir there, which reservoir is fur- nished with a pump, for the purpose of returning the drainings as often as may be desired upon the dung-heap. By this arrangement I do not lose a drop of the saturated liquor that distils from the dunghill. This liquor, in fact, is at length entirely absorbed by the manure when it is ready for cart- ing, unless it has been reserved for the purpose of being employed by itself. " The two compartments are alternately piled with the dung from the stables, which is laid from three to four or five yards thick over the whole surface of the square, trodden down by the feet of the men who fetch it, and abundantly watered by the pumps. " I thus obtain sufficient solidity and moistness, two conditions which I regard as necessary to keep under or subdue the violent fermentation to which stable dung is subject, and which causes the dissi- pation of its most active parts. I add to the situ- SOURCE OF AZOTE. 153 rated liquor sulphate of iron in solution, or I scat- ter over the dung-heap a quantity of sulphate of lime or plaster in powder, with a view to convert- ing into a sulphate the ammonia which is evolved, and which would be dissipated and lost to me if not thus fixed. By these simple and little costly means, in the course of from two or three months I obtain a large quantity of manure perfectly made, as fat and pasty as the dung of neat cattle, and cf great strength, a fact which is abundantly mani- fested in the remarkable crops I have grown on my fields and meadowTs for a number of years past. " Horse-dung piled up absorbs a very consider- able quantity of water, wThich is explained both by its natural dryness, and by the heat it engenders, and the evaporation to which this gives rise. I am convinced that sufficient importance is not attached to this evaporation, and that stable-dung does not receive from the majority of our farmers nearly the quantity of water it requ res. " Urine and the drainings from heaps of fer- mented manure, the ammonia of which has been converted into a sulphate and retained, if distribut- ed over grass-fields and meadows by a watering- cart, produces great luxuriance of vegetation, so that a name written or a figure described in water- ing a meadow is very distinguishable by the supe- rior growth, just as it was easy to form such figures 154 HISTORICAL DATA. by strewing plaster over the surface of the clover- fields in America, when there was an anxiety to ex- tend the use of gypsum in that country. Ammo- nia is an essential part of manure, for whatever purpose employed; and as my process tends to preserve the ammonia, and to prevent its loss by evaporation when the manure is spread, it is obvious that this manure must have a very superior effect. " I do not imagine that I have made any discov- ery here ; the practice of saturating the urine and drainings of dunghills, and of watering meadows with the liquor during damp weather, in the spring as well as after each successive cutting, is old in Switzerland. I only sought to know the nature of the action of sulphate of iron upon fermented urine, and of the powerful effect of the fluid to which it was added upon vegetation. I was natu- rally led to conclude, that the ammonia engender- ed, by decomposing the sulphate of iron, is it- self converted into a sulphate, which, not being volatile, is not dissipated, and so becomes the prin- cipal cause of the great influence exerted by the prepared liquor upon vegetation. I was also led to perceive that horse-dung, by entering into too violent fermentation, by overheating, must cause a dissipation of its volatile ammoniacal parts, and I therefore bethought me of a means of mastering this fermentation as well as of fixing the ammonia. SOURCE OF CARBON. 155 " I have made these principles known upon all occasions. Various proprietors, fond of agricul- ture, have made use of sulphate of iron to saturate the drainings of their dung-hills, without attaching much importance to the result, with the exception of Baron de Gail, a landed proprietor at Miilhau- sen, who has made use of the sulphate of iron and plaster for several years in this direction, and who loudly vaunts the good effects he has obtained from the practice." The preceding letter is accompanied with a doc- ument dated 12th July, 1835, which proves that the facts it contains were at that time publicly an- nounced at the Agricultural Meeting of the Lower Rhine. Source of the Carbon of Plants.—If it be quite evident that plants derive their hydrogen from water, their azote from the air or from ammonia, it is not quite so natural to suppose that their car- bon is obtained exclusively from carbonic acid. We have only adopted on this topic the opinion expressed so far back as 1828 by M. Ad. Brong- niart, in a paper read at one of the public sittings of the Academy of Sciences. These are the terms in which he expresses himself: " The study of the metamorphoses undergone by the vegetable kingdom, if I may be allowed to make use of such an expression, during the for- 156 HlfclORICAL DATA. matron of the crust of the globe, appears, there- fore, to inform us that the temperature and extent of the ocean have been diminishing incessantly from the first appearance of vegetables upon the earth to the present epoch. '• The comparison of the successive develop- ment of plants and animals is not one of the least remarkable points in the study of fossil organized bodies. " We know, in fact, that in the strata of older date than, or of the same epoch as, the coal-for- mations, th re are no remains of any terrestrial animal, whilst at this epoch vegetation had already made great progress, and was composed of plants as remarkable for their forms as for their gigantic stature. At a later peiiod terrestrial vegetation loses in a great measure the signal vigor which it formerly possessed, and cold-blooded vertebrate animals become extremely numerous : this is what is observed during the third period. " Subsequently plants become more varied, more perfect; but the analogues of those that existed originally are reduced to a vastly smaller stature : this is the epoch of the appearance of the most perfect animals, of animals breathing air, of mam- malia, and birds. " Is there no means of discovering some cause adequate to explain in a natural way this vast de- SOURCE OF CARBON. 157 velopment, this vigorous growth of plants breath- ing air, even from the most remote epochs in the formation of the globe 1 And, on the other hand, of the appearance of warm-blooded animals, that is to say, of animals whose aerial respiration is most active in the last periods of its formation only 1 May not this difference in the epoch of the appearance of these two classes of beings de- pend on the difference in their mode of respiration, and of the circumstances in the state of the atmos- phere calculated to favor the development of one and to oppose that of the other 1 " Under what form, at the epoch of the creation of organized beings, did the whole of the carbon exist which these beings subsequently absorbed, and which is now buried with their spoils in the bosom of the earth, or which is still met with dis- tributed among the infinite multitude of organized beings, that actually cover the surface of the globe ? " It is obvious that animals derive carbon neither from the atmosphere nor the soil, but exclusive- ly from their food. " We cannot conceive how plants could have assimilated this carbon had it been in the solid state; and, moreover, in the formations older than those that include the first remains of vegetables, we scarcely encounter any traces of carbon. " This carbon, then, which the vegetables of 14 158 HISTORICAL DATA. the primitive world, and those of the subsequent and present world, absorbed, must necessarily have existed in a shape proper to furnish them with nutriment; and we only know of two,—humus or vegetable mould, which resulting itself from the de- composition of other vegetables wrould lead us into a vicious circle, and carbonic acid, which, decom- posed by the leaves of vegetables under the in- fluence of solar light, deposites its carbon, and so serves for their growth. " It appears to me impossible, therefore, to sup- pose that vegetables can have derived from any- other source than the atmosphere, and in the state of carbonic acid, the carbon which is found in all existing species of plants and animals, as well as that, which after having served the vast primeval forests for sustenance, has been deposited under the form of coal, lignite, and bitumen, in the dif- ferent sedimentary strata of the earth. If we sup- pose, then, that the whole of this carbon was dif- fused through the atmosphere in the shape of Car- bonic acid prior to the creation of organized be- ings, we shall see that the atmosphere, instead of containing less than the one thousandth part of its bulk of carbonic acid, as at present, must have contained a quantity which it is not easy to esti- mate exactly, but which was perhaps in the propor- tion of 3, 4, 5, 6, and even 8 per cent. SOURCE OF CARBON. 159 " We are well assured, by the experiments of M. Th. de Saussure, that carbonic acid, far from- proving detrimental to vegetation, is positively favorable to it when plants are exposed to the sun's light. This highly probable difference in the con- stitution of the atmosphere may, therefore, be re- garded as one of the causes influencing most pow- erfully the more active, and very remarkable vege- tation of the organic period of our globe. " But this same circumstance must, on the con- trary, have interfered materially with the decompo- sition of the remains of dead vegetables and their transformation into soil; for this kind of decom- position is owing essentially to the abstraction of a portion of the carbon of the wood by the oxy- gen of the air; and if the atmosphere contained less oxygen and more carbonic acid, the decompo- sition in question must have been, without doubt, both more difficult and slower. Hence the ac- cumulation of vegetable debris in extensive beds, even in circumstances and from vegetables which, in the actual state of the atmosphere, would give rise to no such layers of combustible material. "On the other hand, this difference in the com- position of the atmosphere, so favorable to the development, growth, and preservation, of vege- table matter, must have proved a bar to the exist- ence of animals, particularly of warm-blooded ani- 160 HISTORICAL DATA. mals, whose respiration, as it is more active, also requires a purer air: during this first period, con- sequently, not a single animal breathing air appears to have existed. " During this period the atmosphere must have been purged of some portion of the excess of car- bonic acid which it contained, by the vegetables which then existed ; these assimilated it first, and subsequently buried it in the state of coal in the bowels of the earth. It is after this first period, in the course of our second and third periods, that this immense variety of monstrous reptiles makes its ap- pearance, animals which, by the nature of their respiration, are capable of living in an atmosphere of much less purity than that which warm-blooded animals require, and were the heralds and precur- sors of these. " Vegetables continued incessantly to abstract a portion of the carbon of the air, and thus rendered it every day more pure; but it was not till after the appearance of a vegetation altogether new, abound- ing in mighty trees, the source and origin of nu- merous deposits of lignite, a vegetation which seems to have covered the surface of the earth with vast forests, that a great number of mamraiferous ani- mals, analogous in all essential features of their or- ganization to those that still exist in the world, ap- peared for the first time upon its surface. PART PLAYED BY PLANTS. 161 " Would it not be fair to suppose from this that our atmosphere had now arrived at that degree of purity which could alone comport with the active respiration of warm-blooded animals, and prove alike favorable to the development of plants and animals, whilst the simultaneous existence of these two orders of beings, and the inverse influence of their respiratory actions, conduce to maintain our atmosphere in the state of stability, which is one of the remarkable characters of the present pe- riod ?" General Views in regard to the part played by Plants in the Economy of Nature.—It was from the whole of the preceding considerations and ex- perimental conclusions, that we drew up the fol- lowing heads as the basis of our researches, and as a kind of synopsis of our lectures upon the particu- lar branch of our subject interested: Plants are a Reducing Apparatus. They decompose carbonic acid, water and oxide of ammonium or nitric acid They fix carbon, hydrogen,and azote, or ammonium. They disengage oxygen. They absorb caloric, or light. 14* 16^ HISTORICAL DATA. They produce sugar, starch, and gum, fatty substances, fibrine, albumen, and caseum. In this list there are two opinions which, per- haps, are not sufficiently justified by the results pre- viously announced. The first is that which assumes as essential to plants the faculty of absorbing caloric or light; this opinion was derived from a paper presented to the Academy of Sciences by M. Boussingault, in 1837, in which the author, contrasting the meteo- rological circumstances, in which wheat, barley, Indian corn, and the potato, are developed at the equator and in temperate zones, arrives at the con- clusion " That the same annual plant, every- where, receives the same quantity of heat in the course of its existence." We have since then been accustomed to regard this heat as one of the prin- cipal agents, by means of which the phenomena of vegetation are accomplished.* * " All the chemical changes that mark the course of na- ture, are attended with changes of temperature, from the slowest process of fermentation to the most rapid combustion; that is, all the decompositions and recombinations of matter are attended with the addition or subtraction of caloric. Without the continual agency of the solar beams, the vital air, the ocean and the solid, would become a motionless mass of inert and chaotic matter. Without the reception of caloric PART PLAYED BY PLANTS. 163 The second of the opinions which we have to justify by facts, is the existence of fibrine, albumen, and caseum, in plants. With regard to fibrine, it is generally know7n that M. Vauquelin was the first who, long ago, recog- nized the existence of this proximate principle in the sap of the Carica papaya. Messrs. Boussin- gault and Rivero, on their part, also admitted the existence of fibrine in the milk of the Paolo de vacca, or cow-tree. Their paper, published in 1823 (" Annales de Chimie," torn, xxiii. p. 222), con- tains the following passage : " Thus obtained, the fibrous substance is brown, because it is undoubtedly slightly altered by the temperature of melting wax; it is tasteless; on hot iron it swells and twists about, melts, and is car- bonised with the odor of broiled meat. " Heated with dilute nitric acid, a gas was dis- engaged which was not nitrous acid gas. The fibrous substance was changed into a yellow and from the atmosphere by respiration, the wonderful mechanism of animal motion, sensation, and life, could not go on."—On f Caloric, its Mechanical, Chemical, and Vital Agencies in the Phenomena of Nature, by Samuel L. Metcalfe, M.D., London, 1843. An admirable work ; full of original, grand, and com- prehensive views; to chemistry at large, physiology, and general physics, all that Professor Dumas's elegant Dis- course is to the vegetable and animal kingdoms of nature in particular.—Editor. 164 HISTORICAL DATA. greasy mass, in the same way as muscular flesh, when nitrogen is prepared from it by the process of M. Berthollet. " Alcohol does not take up this fibrous matter ; and we made use of this fluid to procure it un- changed. By treating the extract of vegetable milk repeatedly with hot alcohol, and decanting the liquid, it is finally obtained in the form of white and flexible fibres ; in this state it dissolves read- ily in dilute hydrochloric acid. The substance, therefore, possesses the same characters as animal fibrine. " The presence in this vegetable milk of a sub- stance which is not generally met with, save in the secretions of animals, is a very surprising fact, which we should not announce without much hesi- tation, had not one of our most distinguised che- mists, M. Vauquelin, already discovered animal fibrine in the milky juice of the carica papaya." M. Dumas, in his Course of 1839, admitted the identity with fibrine of the part of wheat gluten which alcohol refuses to dissolve. With reference to albumen, every one has ac- knowledged its existence in vegetables; but it is imperative on us to mention M. Mulder in this place, this chemist having first proved that the composition of vegetable albumen was the same as that of animal albumen, and who deduced the PART PLAYED BY PLANTS. 165 important consequence, " that the great mass of animal substances is supplied by the vegetable kingdom." Finally, when we quoted the existence of case- um in vegetables, we had in view the opinion of Proust, who looked on the azotised matter of al- monds as caseum; that of Braconnot, who viewed the azotised substance of pease and beans as ca- seum, and that which M. Dumas had advanced in his course of 1839, touching the existence of case- um in the gluten of wheat. The opinions of Proust and Braconnot have not been borne out by subse- quent researches, as appears from the paper of Messrs. Dumas and Cahours; but hitherto nothing has shaken M. Dumas's conclusions relative to the caseum of gluten. All the opinions comprised in the foregoing syl- labus were therefore publicly announced or actually published by us previously to 1839. We imagined that it was competent for us in 1841, in the Discourse which has just been read, to give a general sketch of views which we had f already published, which had taken five or six years to reduce themselves to shape in our mind, and which we had in every instance felt bound to connect with positive experiments before venturing to o-ive them utterance in words. 166 HISTORICAL DATA. We are equally satisfied that if the views which are associated in this discourse preserve in future times the importance which is assigned to them now, it will remain a matter of demonstration, that the principal labors upon which these views are founded have been performed in France,* and that their association as a general formula must be re- ferred to Lavoisier, who gave the impulse to physi- olgy which we have followed out. If we deceive ourselves in this, the fact will be easily shown. It will only be necessary to prove that we were in error when we ascribed : 1st. To Lavoisier, the discovery of the theory of animal heat, that of the part which animals play as consumers of carbon and hydrogen, the function which characterizes their influx, and the first ap- plication of the balance to the study of the pheno- mena of life; 2d. To Sennebier, the discovery of the decom- position of carbonic acid by vegetables; 3d. To Boussingault, the discovery of the de- composition of water by vegetables; the use of the balance in studying the phenomena of vegeta- tion ; 4th. To Schattenmann and Davy, the discovery of the intervention of ammonia in the process of vegetation; See Appendix, Note L. HISTORICAL DATA. 167 5th. To Ad. Brongniart and Parrot, the first thought of assigning to the carbonic acid of the atmosphere the origin of all the carbon of organ- ized beings; 6th. To Vauquelin, Boussingault, Mulder, Proust, and Braconnot, the discovery of fibrine, al- bumen, and caseum in vegetables; 7th. To Dumas and Boussingault, the discovery of the reducing faculty of the vegetable kingdom at large over the face of the earth; 8th. To Chevreul, the true theory of the respi- ration of animals WORKS AND PAPERS REFERRED TO. (1) Memoire sur la composition de l'Eau, Dumas et Stas, Ann. de chirn. et de phys., 3' serie, juin 1843. (2) Memoire sur le poids atomique du Carbone, Dumas et Stas» Ann. de chim. et dephys., 3e serie, 1.1, p. 5. Idem, Erdmann et Marchand, Ann. de chim. el de phys., 3' serie, t. III. p. 500. (3) Berthollet, Ann. de chim. etdephys.,t XXII. p. 97. (4) Recherches sur la veritable constitution de l'Air atmos- pherique, Dumas et Boussingault. Ann. de chim. et de phys., 3e serie, t. III. p. 257. (5) Recherches sur la variation de I'Acide Carbonique atmospherique, Th. de Saussure, Ann. de chim. et de phys., t. II. p. 199 ; et Ann. de chim. et de phys., t. XLIV. p. 5. Boussingault, Comptes-rendus des seances de lAcademie des sciences, 1840. Brunner, Ann. de chim. et de phys., 3' serie, t. III. p. 312. Gay-Lussac, Ann. de chim. et de phys., t. II. p. 204. (6) Boussingault, Ann. de chim. et dephys., t. LVTI. p. 448. (7) Recherches sur les variations de I'Acide Carbonique avec les saisons, Th. de Saussure, Ann. de chim. et de phys., t. XLIV. p. 5. (8) Opinion de M. Gay-Lussac sur le travail precedent, Gay-Lussac, Ann. de chim. et de phys., t LII. p. 92. 170 WORKS AND PAPERS REFERRED TO. (9) Consideration sur la nature des Vegetaux qui ont couvert la surface de la Terre aux diverses epoques de sa Formation, Adolphe Brongniart, Comptes-rendus des seances de lAcademie des sciences, t. V. p. 409. 10) Recherches sur le Ligneux, 1'Amidon et la Dex- trine, Payen, Ann. de chim. et de phys., t. LXV. p. 225. Dumas, Rapport sur le Memoire precedent. Comptes- rendus des seances de I'Acade'mie des sciences, t. V. • p. 898. Dumas, Rapport sur un Memoire de M. Payen relatif a. la composition de la Matiere Ligneuse. Comptes- rendu des seances de I'Acade'mie des sciences, t. VIII. p. 5r (11) Recherches chimiques sur la Vegetation, Dumas, Rapport sur un Memoire de M. Boussingault, rela- tif a des Recherches chimiques sur la Vegetation. Comptes-rendus des seances de I'Academie des sciences, t. VIII. p. 54. (12) Schattenmann, v. p. 134. (13) Recherches sur les Matieres Neutres Azotees de l'Or- ganisation, Dumas et Cahours, Ann. de chim. et dephys,. 3' serie, t. VI. p. 385. (14) Recherches sur les Cendres des Vegetaux, Boussin- gault, Observations inedites. (15) Recherches sur la Vegetation et la Germination, Bous- singault, Comptes-rendus des seances de I'Academie des sciences, t. VI. p. 102. (16) Opinion sur la Chaleur Animale, Dumas, Lemons de philosophic chimique, p. 79. (17) Recherches sur la Chaleur Animale, Despretz, Ann. de chim. et dephys., t. XXVI. p. 341. WORKS AND PAPERS REFERRED TO. 171 (18) Recherches sur la Determination de la Quantite d'Uree, contenue dans l'Urine, Lecanu, Journal de pharmacie, t. XVII. p. 649 ett. XXV. p. 681. (19) Recherches sur la Composition de l'Uree, Dumas, Ann. de chim. et de phys , t. XLIV. p. 273. (20) Recherches sur la Transformation de l'Uree en Car- bonate d'Ammoniaque, Jacquemart, Ann. de chim. et de phys., 3' serie, t. VII. p. 449. (21) Dumas, Lemons de philosophic chimique. Andral el Gavarret, Ann. de chim. et de phys., 3= serie, t. VIII. p. 129. (22) Recherches sur la Digestion des Matieres Grasses Tiedemann et Gmelin, Recherches sur la digestion, t. I. p. 192. (23) Recherches sur la Digestion, Bouchardat et Sandras, Ann. de chim. et de phys., 3° serie, t. V. p. 478. (24) Dumas, Boussingault et Payen, Ann. de chim. et de phys., 3' serie, t. VIII. p. 63. Dumas et Cahours, Ann. de chim. et dephys., 3' serie, t, VI. p. 385. (25) Dumas, Philosophic chimique, T lecon. (26) Recherches sui la Maniere dont se comporte I'Acide Gallique en Presence des Alcalis, Chevreul. (27) Thomas, Note communicated to M. Dumas. (28) Recherches Chimiques sur la Vegetation, Boussin- gault, Comptes-rendus ^ des seances de I'Academie des sciences. (29) Dumas, Lemons de philosophic chimique, t. II. p. 90 APPENDIX. NOTE A.—Page 29. It will be remembered that Dumas advocates the views of Dr. Thompson in respect to chemical equivalents.— D. P. G. B.—Page 30. From the same source sulphuretted, and a minute quanti- ty of phosphuretted hydrogen are evolved.—(See the Editor's paper, Am. Journal Med. Sciences, Apr. 1843.)—D. P. G. C—Page. 31. Liebig has made a general estimate of the proportion of ammonia at gfi . in vol.—D. P. G. o 0 0 0 o D.—Page 40. The rays of light which produce marked effects upon vegetation are not those which act on Daguerre's plate.— (See the Editor's paper, London and Edinb. Phil. Mag., Jan., 1844. E.—Page 42. The hydrogen of ammonia decomposed by plants is re- Sained.—D. P. G. APPENDIX. 173 F.—Page 43. this is effected in practice by turning in clover, a plant that absorbs nearly all its azote.—D. P. G. G.—Page 48. See the Editor's paper, London and Edinb. Phil. Mag.i July, 1842. H.—Page 49. This is true also in the corn plant, which, when culti- vated for sugar, should be hindered from developing the ears.—D. P. G. I.—Page 52. In the recent experiments of Brunner and Valentin, the difference of nitrogen between atmospheric air and expired air is not greater than may arise from errors of observation^ and they consider it inactive. Liebig, admitting its occasional presence, refers it to the penetration of the nitrogen of atmos- pheric air taken into the stomach with saliva. In the same way the nitrogen dissolved in water could pass out by the skin and lungs.—D. P. G. J—Page 58. The view here advocated that animals receive all their fat from vegetables has been abandoned in part by M. Dumas. Liebig had in his Animal Chemistry advanced the doctrine of the transformation of amylaceous substances into fat in the animal economy. He based it on the researches of Grund- lach on bees. A difference of opinion having arisen MM. Dumas and Milne Edwards proceeded to determine the point experimentally. They selected a hive of 1988 bees, and placed them in a proper vessel where they received honey 174 APPENDIX. only as food for thirty-one days. One hundred and five bees were analyzed before the experiment—and one hundred and seventy-seven afterwards to determine the amount of fat they contained. The result of the experiment communicated to the Academy of Science, Sept. 18th, 1843, showed that there had been an actual transformation of honey into wax, amounting to 0-0742 gramme by each insect. It will be understood, therefore, that animals receive fat from vegetables and are also able to transform starch, sugar, gum, &c, into that body.—D. P. G. K.—Page 68. The ammonium theory owes its existence to the discovery of the ammoniacal amalgam by Berzelius. In its formation one atom of ammonia and one atom of water are acted on by galvanism in the presence of mercury ; a bulky pasty amal- gam' results at the negative, and one atom of oxygen is liber- ated at the positive pole. This body consists, therefore, of N. H.4—united with mercury. It has the general characters of sodium and potassium, and forms chlorides, ■ iodides, &c. For the production of oxygni salts it is neces- sary that the ammonium be in the state of oxide or N. H.44- 0., which contains the elements of one atom ammonia, and one atom water, and exists only in combination. "We are under no necessity to consider ammonium a metal, but a compound radical similar to Ethyl, &c.—D. P. G. L—Page 167. The Editor wishes to disavow the presumptuous assertion of M. Dumas that the principal labors tending to the present development of animal and vegetable physiology are of Parisian origin.—D. 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