Class. 
 Book- 
 

 ORGANIC CHEMISTRY 
 
 ITS APPLICATIONS 
 
 AGRICULTURE AND PHYSIOLOGY. 
 
ORGANIC CHEMISTRY 
 
 IN ITS APPLICATIONS 
 
 AGRICULTURE AND PHYSIOLOGY. 
 
 JUSTUS LIEBIG, M.D., Ph.D., F.R.S., M.R.I.A., &c., 
 W 
 
 PROFESSOR OF CHEMI9TKY IN THE UNIVERSITY OF GIESSEN. 
 
 EDITED FROM THE MANUSCRIPT OF THE AUTHOR 
 By LYON PLAYFAIR, Ph.D. 
 
 FIRST AMERICAN EDITION, 
 
 WITH AN 
 
 INTRODUCTION, NOTES, AND APPENDIX, 
 
 JOHN W. WEBSTER, M.D., 
 
 1 ^ 
 
 PROFESSOR OF CHEMISTRY IN HARVARD UNIVERSITY. 
 
 CAMBRIDGE: 
 PUBLISHED BY JOHN OWEN. 
 
 BOSTON, JAMES MUNROE AND COMPANY, AND C. C. LITTLE AND J. BROWN J 
 NEW YORK, WILEY AND PUTNAM, AND GEO. C. THORBURN J 
 PHILADELPHIA, THOMAS, COWPERTH WAIT, AND COM- 
 PANY, AND CARY AND HART ; BALTIMORE, 
 CUSHING AND BROTHER. 
 
 1841. 
 

 \ 
 
 % 
 
 Entered according lo Act of Congress, in tiie year 1841, by 
 
 John Owen, 
 
 in the Clerk's Office of llie District Court of tlie District of Massachusetts 
 
 CAMBRIDGE: 
 
 FOLSOM, WELLS, AND THURSTON, 
 
 PBINTEBS TO THE UNIVERSITY. 
 
 
CONTENTS. 
 
 INTRODUCTION. 
 
 FIRST ELEMENTS OF CHEMISTRY. 
 
 CHAPTER PAGE 
 
 I. Definitions 1 
 
 II. Affinity — Crystallization .... 15 
 
 Combination 22 
 
 Decomposition .... 25 
 
 III. Laws of Chemical Proportion ... 32 
 
 IV. Theory of Chemical Proportions . . 36 
 V. Connexion between the Atomic Weight and 
 
 Volume of a Body ..... 41 
 
 VI. Isomorphism. Catalytism .... 42 
 
 VII. Theory of the Constitution of Salts . 46 
 
 PART FIRST. 
 
 I. On the Chemical Processes in the Nutrition 
 OF Vegetables, and the Constituent Ele- 
 ments of Plants 53 
 
 II. On the Assimilation of Carbon ... 57 
 
 III. On the Origin and Action of Humus . . 95 
 
 Vegetable Mould 97 
 
 IV. On the Assimilation of Hydrogen . . . 120 
 
 V. On the Origin and Assimilation of Nitrogen 126 
 VI. On the Inorganic Constituents of Plants . 147 
 
 VII. The Art of Culture 169 
 
 VIII. On the Interchange of Crops, and of Manure 206 
 
 PART SECOND. 
 
 OF THE CHEMICAL PROCESSES OF FERMENTATION, DECAY, 
 AND PUTREFACTION. 
 
 1. Chemical Transformations .... 249 
 II. On the Causes which Effect Fermentation, 
 
 Decay, and Putrefaction .... 252 
 
VI 
 
 CONTENTS. 
 
 III. 
 IV. 
 
 V. 
 
 VI. 
 VII. 
 
 VIII. 
 
 IX. 
 X. 
 
 XI. 
 
 Fermentation and Putrefaction 
 
 On the Transformation of Bodies which do 
 NOT contain Nitrogen as a Constituent, 
 AND of those in whi(;h it is present . 
 
 Fermentation of Sugar .... 
 
 Eremacausis, or Decay 
 
 Eremacausis, or Decay, of Bodies which do not 
 contain Nitrogen : Formation of Acetic Acid 
 
 Eremacausis of Substances containing Nitro- 
 gen. Nitrification 
 
 On Vinous Fermentation: — Wine and Beer 
 
 On the Mouldering of Bodies. — Paper, Brown 
 Coal, and Mineral Coal .... 
 
 On Poisons, Contagions, and Miasms 
 
 261 
 
 266 
 275 
 
 285 
 
 293 
 
 299 
 303 
 
 325 
 
 335 
 
 APPENDIX. 
 
 Growth of Plants without Mould 383 
 
 On the Action of Charcoal on Vegetation . . . 386 
 
 On the Rotation of Crops at Bingen, on the Rhine . 390 
 
 On a mode of Manuring Vines 390 
 
 On the Manuring of the Soil in Vineyards . . . 391 
 
 Dr. Dana's Views respecting Geine ..... 394 
 
 Analysis of Soils from Russia, &c. .... 409 
 
 Berzelius on Animal Manure and Lime . . . 410 
 
 Action of Ammonia ....... 411 
 
 Root Secretions . . . . . . . .411 
 
 Phosphate of Lime in Soils ..... 412 
 
 Peat Compost 413 
 
 Collection and Use of Manure in China . . . 415 
 
 Addition to Note at Page 70 416 
 
 Tables showing the Proportion between the Hessian and 
 
 English Standard of Weights and Measures . 416 
 
 Square Feet 418 
 
 Cubic Feet 418 
 
 Table of the Corresponding Degrees on the Scales of 
 
 Fahrenheit, Reaumur, and Celsus, or Centigrade 419 
 
 Index 421 
 
PREFACE 
 
 TO THE AMERICAN EDITION. 
 
 The interest excited in Great Britain on the 
 appearance of this work by one of the most 
 eminent chemists in Europe, and the high en- 
 comiums bestowed upon it by individuals, and 
 learned bodies, together with the various no- 
 tices of it which have been published by Pro- 
 fessor Lindley, Professor Daubeny, and others, 
 all concurring in the opinion, that the informa- 
 tion it contains is of great amount, and that 
 from its publication might be dated a new era 
 in the art of agriculture, induced the editor to 
 suggest its republication in this country. 
 
 As it was highly desirable to put the views 
 of Professor Liebig to the test of actual experi- 
 ment, arrangements were made for the cultiva- 
 tion of a variety of plants upon the principles 
 developed in the work. With his usual liber- 
 ality and readiness in aiding the advancement 
 of agriculture and horticulture, a gentleman in 
 this vicinity, whose unrivalled conservatories 
 and grounds afford the amplest facilities, per- 
 
Vm PREFACE TO THE AMERICAN EDITION. 
 
 mitted a series of experiments to be instituted, 
 upon many of his plants, trees, vines, and vege- 
 tables. Other highly successful cultivators have 
 also experiments in progress. The wish of the 
 publisher to meet the frequent calls for the work 
 at an early period, permitted, at this season of 
 the year, only of such experiments as could be 
 conducted under glass, which could not be ex- 
 pected to furnish results of so much value as 
 would have been the case had the publication 
 been deferred to the autumn. The experi- 
 ments, however, will be continued and varied 
 during the summer, upon plants in the open 
 air, and it is hoped, that more satisfactory re- 
 sults will be arrived at. In the mean time, 
 other cultivators, who may be induced to study 
 the work, will have an opportunity of applying 
 the principles on every variety of soil and agri- 
 cultural product. With the hope of being able 
 to embody, in this edition, the fruits of some 
 of the experiments alluded to, its publication 
 was for a time deferred. 
 
 Although the experiments have not been in 
 progress a sufficient length of time to allow in all 
 cases of very decided inferences, in several instan- 
 ces the growth and luxuriance of the plants have 
 been highly satisfactory. The plant which was 
 first treated was a seedling Norfolk Island pine 
 (Araiicaria excelsa), a superb species of the 
 
PREFACE TO THE AMERICAN EDITION. IX 
 
 larger coniferse. This plant was reared bj the 
 editor in a pot, in which it has been growing 
 three years, in the house. The growth each 
 year has been from four to five inches, between 
 October and April. In January last, it was 
 supplied with charcoal-powder and ammonia? 
 and watered with rain-water. Very soon it 
 exhibited symptoms of increasing vigor, and has 
 continued to flourish, having, at the expiration 
 of thirteen weeks, increased in height rather 
 more than six inches, with much new foliage, 
 and several lateral shoots. 
 
 The application of ammonia and charcoal to 
 dwarf fruit-trees and grape-vines in pots, which 
 was made more recently, has as yet produced 
 no very obvious results. These would probably 
 have been more evident, good or bad, had not 
 an oversight of the gardener led to the neglect 
 of an important step in the process, the direc- 
 tions not having been distinctly understood. 
 
 Experiments have been also made upon quick 
 growing vegetables under glass ; boxes being 
 so arranged, that the plants in every alternate 
 box could be treated on Liebig's principles, 
 while an equal number, containing plants of 
 the same kind, were treated in the usual man- 
 ner, and thus a comparison could be readily 
 made. Of these, beans have exhibited the most 
 apparent results. 
 
X PREFACE TO THE AMERTCAN EDITION. 
 
 The application of the ammonia and charcoal 
 to several green-house plants, has had most ef- 
 fect, as jet, upon geraniums, and in the con- 
 servatory in Boston, under the judicious and 
 scientific direction of J. E. Teschemacher, Esq., 
 the foliage has exhibited extraordinary devel- 
 opement. We have yet to learn how far the 
 flowers and fruit of the various plants under 
 trial will be affected. 
 
 The great object is to supply in moderate 
 quantity, but constantly, ammonia, in what 
 chemists term the nascent state, that is, as it 
 is slowly evolved, from a salt containing ammo- 
 nia, or produced, or as given off from charcoal 
 which has absorbed it. This may be done by 
 causing the slow decomposition of muriate of 
 ammonia (sal ammoniac) by the aid of lime. 
 
 Ammonia-water added in small quantity to 
 rain-water may be given to the soil in which 
 the plants are growing; or carbonate of ammo- 
 nia dissolved in rain-water. 
 
 Half an ounce of ammonia-water to a gallon 
 of rain-water appears to be of sufficient strength; 
 but in this we must be regulated by the nature 
 of the plants to which it is to be given. In 
 some cases the muriate of ammonia has been 
 mixed with the charcoal, and the soil with air- 
 slacked lime, the whole then mingled and placed 
 
PKEFACE TO THE AMERICAN EDITION. XI 
 
 around the roots of the plant. In these cases, 
 it is necessary to supply rain-water liberally to 
 the soil. 
 
 These are the outlines of the methods which 
 have been thus far employed, and as yet no in- 
 jurious effects have been observed, but on the 
 contrary, the general appearance, and in some 
 the growth and healthy aspect of the plants, 
 have been remarkable. 
 
 Although the fact that nitrogen is essential 
 to the nutrition of plants was known before the 
 publication of Professor Liebig's work, and it 
 had, indeed, been ascertained by Saussure, that 
 germinating seeds absorb nitrogen, it was not 
 supposed that it is derived from the atmosphere 
 exclusively. And this has been deemed the 
 chief discovery of the author, so far as practical 
 questions are concerned. It had been suspect- 
 ed, that very small quantities of this gas in the 
 atmosphere might furnish the nitrogen, ammo- 
 nia being a compound of nitrogen and hydro- 
 gen. It may be objected, that the quantity of 
 ammonia present in the atmosphere, and in rain 
 and snow water is exceedingly small, quite in- 
 sufficient for the supply of all that enters into 
 the vegetable structure. To this it has been 
 replied by Professor Lindley, in an elaborate 
 review of Liebig's work, that " the quantity of 
 ammonia given off from thousands of millions 
 
XIV PREFACE TO THE AMERICAN EDITION. 
 
 also the injurious action of weeds is explained, 
 by their robbing the soil of that particular kind 
 of food which is necessary to the crops among 
 which they grow. Each will partake of the 
 component parts of the soil, and in proportion 
 to the vigor of their growth, that of the crop 
 must decrease ; for what one receives the oth- 
 ers are deprived of." 
 
 "It is impossible for any one acquainted with 
 gardening not to perceive the immense impor- 
 tance of these considerations, which show, that 
 by adopting the modern notion, that the action 
 of soil is chiefly mechanical, the science of 
 horticulture has been carried backwards, instead 
 of being advanced ; and that the most careful 
 examination of the chemical nature both of the 
 soil in which a given plant grows, and of the 
 plant itself, must be the foundation of all exact 
 and economical methods of cultivation." 
 
 In the English edition, this work is divided 
 into two parts. The original intention of the 
 publisher was to issue only that part which re- 
 lates more particularly to agriculture. With 
 this view, a few pages, viz. those in which vege- 
 table mould and the decay of woody fibre are 
 discussed, were transferred from the second to 
 the first part. The publication of the entire 
 work was decided upon after several pages had 
 been printed, and the title of the first chapter 
 
PKEFACE TO THE AMERICAN EDITION. XV 
 
 having been altered bj the omission of the word 
 physiology, in conformity with the original plan, 
 it was unavoidably allowed so to remain. 
 
 This edition now comprises the entire work. 
 A iew of the chemical illustrations have been 
 transferred to the appendix, as less likely to 
 interest readers in general, although of impor- 
 tance to the chemist. 
 
 The work has been divided into chapters, 
 which will render it more convenient than the 
 English edition. An introduction explanatory 
 of chemical terms and of some of the theoreti- 
 cal views of Liebig, has been prefixed, being a 
 translation from a work of the same author. 
 Many pages of notes explanatory of technical 
 terms, &c., have been supplied ; these have not 
 been distinguished by any mark, while those 
 that are contained in the original work are 
 marked L. or Trans. 
 
 In the Appendix will be found many addi- 
 tions, both theoretical and practical, comprising, 
 it is believed, an impartial statement of the 
 opinions and views of the distinguished Ameri- 
 can chemists, who have with so much zeal and 
 acuteness engaged in the investigation of the 
 chemistry of agriculture. 
 
 A copious index has been prepared and add- 
 ed, in which the original work is deficient. A 
 few grammatical errors in the original have 
 been corrected. 
 
XVI PREFACE TO THE AMERICAN EDITION. 
 
 The estimation in which this work was view- 
 ed by the "British Association for the Advance- 
 ment of Science," before whom it was brought 
 as a Report, has been expressed by Professor 
 Gregory, of King's College, in the remark, "that 
 the Association had just reason to be proud of 
 such a work, as originating in their recommen- 
 dation." 
 
 On the 30th of November, 1840, at the an- 
 niversary meeting of the Royal Society, one of 
 the Copley medals was awarded to the author ; 
 and on this occasion, in his absence, the Presi- 
 dent, the Marquis of Northampton, addressed 
 his representative. Professor Daniell, as follows. 
 
 " Professor Daniell, I hold in my hand, and 
 deliver to you one of the Copley medals, which 
 has been awarded by us to Professor Liebig. 
 My principal difficulty, in the present exercise 
 of this the most agreeable part of my official 
 duty, is to know whether to consider M. Lie- 
 big's inquiries as most important in a chemical 
 or in a physiological light. However that may 
 be, he has a double claim on the scientific world, 
 enhanced by the practical and useful ends to 
 which he has turned his discoveries." 
 
 J. W. W. 
 
 Cambridge, April 9th, 1841. 
 
TO 
 
 THE BRITISH ASSOCIATION 
 
 ADVANCEMENT OF SCIENCE. 
 
 One of the most remarkable features of mod- 
 ern times is the combination of large numbers 
 of individuals representing the whole intelli- 
 gence of nations, for the express purpose of 
 advancing science by their united efforts, of 
 learning its progress, and of communicating 
 new discoveries. The formation of such asso- 
 ciations is, in itself, an evidence that thej were 
 needed. 
 
 It is not every one who is called by his situ- 
 ation in life to assist in extending the bounds 
 of science ; but all mankind have a claim to 
 the blessings and benefits which accrue from 
 its earnest cultivation. The foundation of sci- 
 entific institutions is an acknowledgment of 
 these benefits, and this acknowledgment pro- 
 ceeding from whole nations may be considered 
 as the triumph of mind over empiricism. 
 
 Innumerable are the aids afforded to the 
 means of life, to manufactures and to commerce, 
 
XVIU PREFACE. 
 
 by the truths which assiduous and active in- 
 quirers have discovered and rendered capable 
 of practical application. But it is not the mere 
 practical utility of these truths which is of im- 
 portance. Their influence upon mental culture 
 is most beneficial ; and the new views acquired 
 by the knovi^ledge of them enable the mind to 
 recognise, in the phenomena of nature, proofs 
 of an infinite wisdom, for the unfathomable pro- 
 fundity of which, language has no expression. 
 
 At one of the meetings of the chemical sec- 
 tion of the " British Association for the Ad- 
 vancement of Science," the honorable task of 
 preparing a report upon the state of organic 
 chemistry was imposed upon me. In the pres- 
 ent work I present the Association with a part 
 of this report. 
 
 I have endeavoured to develope, in a manner 
 correspondent to the present state of science, 
 the fundamental principles of chemistry in gen- 
 eral, and the laws of organic chemistry in par- 
 ticular, in their applications to agriculture and 
 physiology ; to the causes of fermentation, de- 
 cay, and putrefaction ; to the vinous and ace- 
 tous fermentations, and to nitrification. The 
 conversion of woody fibre into wood and min- 
 eral coal, the nature of poisons, contagions, and 
 miasms, and the causes of their action on the 
 living organism, have been elucidated in their 
 chemical relations. 
 
PREFACE. 
 
 I shall be happy if I succeed in attracting 
 the attention of men of science to subjects 
 which so well merit to engage their talents and 
 energies. Perfect agriculture is the true foun- 
 dation of all trade and industry, — it is the 
 foundation of the riches of states. But a ra- 
 tional system of agriculture cannot be formed 
 without the application of scientific principles ; 
 for such a system must be based on an exact 
 acquaintance with the means of nutrition of 
 vegetables, and with the influence of soils and 
 action of manure upon them. This knowledge 
 we must seek from chemistry, which teaches 
 the mode of investigating the composition, and 
 of studying the characters of the different sub- 
 stances from which plants derive their nourish- 
 ment. 
 
 The chemical forces play a part in all the 
 processes of the living animal organism ; and a 
 number of transformations and changes in the 
 living body are exclusively dependent on their 
 influence. The diseases incident to the period 
 of growth of man, contagion and contagious 
 matters, have their analogues in many chemical 
 processes. The investigation of the chemical 
 connexion subsisting between those actions pro- 
 ceeding in the living body, and the transforma- 
 tions presented by chemical compounds, has 
 also been a subject of my inquiries. A perfect 
 
XX PREFACE. 
 
 exhaustion of this subject, so highly important 
 to medicine, cannot be expected without the 
 cooperation of physiologists. Hence I have 
 merely brought forward the purely chemical part 
 of the inquiry, and hope to attract attention to 
 the subject. 
 
 Since the time of the immortal author of the 
 " Agricultural Chemistry," no chemist has oc- 
 cupied himself in studying the applications of 
 chemical principles to the growth of vegetables, 
 and to organic processes. I have endeavoured 
 to follow the path marked out by Sir Humphry 
 Davy, who based his conclusions only on that 
 which was capable of inquiry and proof. This 
 is the path of true philosophical inquiry, which 
 promises to lead us to truth, — the proper ob- 
 ject of our research. 
 
 In presenting this report to the British Asso- 
 ciation, I feel myself bound to convey my sin- 
 cere thanks to Dr. Lyon Playfair, of St. An- 
 drews, for the active assistance which has been 
 afforded me in its preparation by that intelligent 
 young chemist during his residence in Giessen. 
 I cannot suppress the wish, that he may suc- 
 ceed in being as useful, by his profound and 
 well-grounded knowledge of chemistry, as his 
 talents promise. 
 
 DR. JUSTUS LIEBIG. 
 Giessen, September 1st, 1840. 
 
INTRODUCTION. 
 
 FIRST ELEMENTS OF CHEMISTRY.* 
 
 CHAPTER I. 
 
 DEFINITIONS. 
 
 1. The term Body is applied to all that, which occu- 
 pies a certain space and possesses weight, that is, that 
 which is attracted by the earth, 
 
 2. In a more restricted sense, that which occupies 
 space, is denominated Matter. In the most extended 
 signification, matter is that which in any way becomes 
 cognoscent to our senses. 
 
 3. Bodies are found in three states, (a) solid, (b) flu- 
 id, and (c) gaseous, or aeriform. 
 
 (a). A body is denominated solid, when it possesses 
 a particular form and its particles are difficultly or not 
 movable among one another. 
 
 (b). A fluid body is so named, when it takes the 
 form of the vessel in which it is contained ; its particles 
 
 * Selected and translated from Professor Liebig's new edition of 
 Geiger's Pharmacy, published at Giessen. 
 1 
 
2 INTRODUCTION. 
 
 are easily movable among one another, and in a state of 
 rest its surface is horizontal. 
 
 (c). Gaseous bodies have no particular form ; their 
 particles possess the property of repelling one another, 
 and they perfectly fill the vessel in all directions which 
 contains them. 
 
 4. Extension. The space which a body occupies, 
 according to its length, breadth, and depth, gives the 
 idea of its figure. The bulk of a body is named its 
 volume. 
 
 5. The quantity of matter contained in a certain vol- 
 ume is denominated its mass. 
 
 6. The comparison of the mass of different bodies of 
 the same volume, gives the notion of their density. We 
 say that one body is denser than another, when in the 
 same volume, the mass is greater in one than in the 
 other. 
 
 7. The phenomena which a body presents, while it 
 acts upon our senses, are named the properties of the 
 body. 
 
 8. The cause which effects the changes in the material 
 world, is named poxoer. 
 
 9. Power effects either a change in the position or 
 properties of a body. 
 
 10. The influence which causes a body .or the par- 
 ticles of the same to approach one anotheA is named 
 attraction. 
 
 11. Repulsion is defined to be that power which op- 
 poses the power of attraction. 
 
 12. Besides the power of attraction and repulsion 
 certain matters have a decisive influence upon the changes 
 in the properties of a body. These matters arc named 
 imponderables. They are heat, light, electricity^ and 
 magnetism. 
 
DEFINITIONS. GRAVITY. 3 
 
 13. Three different powers of attraction are known, 
 (a) gravity, (b) power of cohesion, and (c) chemical 
 affinity. 
 
 14. Gravity is distinguished from all other powers of 
 attraction, in that, it acts at great distances. 
 
 15. The force of this attraction stands in direct rela- 
 tion to the mass of the body ; it increases inversely as 
 the square of the distance. 
 
 16. Since the mass of a body can be taken infinitely 
 small in relation to the mass of the earth, it follows from 
 (15), that every body, removed from the surface of the 
 earth and left at liberty, must obey the attraction of the 
 earth, and consequently fall. 
 
 17. Two bodies on the surface of the earth show no 
 observable inclination to approach one another, while the 
 preponderating attractive power of the earth overcomes 
 their particular mutual attraction. 
 
 18. The force, with which one body presses upon 
 another, depends upon the mutual attractive power of 
 the earth and of the body ; it stands in proportion to the 
 mass of the body. 
 
 19. The greater or smaller mass of a body is meas- 
 ured, by certain unities of mass called iceights. The 
 instrument balance is employed to learn how much of the 
 unities of mass are necessary in order to bring the mass 
 of the body in equilibrium. 
 
 20. The intensity of this counter-pressure, expressed 
 in weights, is denominated the absolute weight of the 
 body. Bodies of the same volume possess different ab- 
 solute weights. The different weights of the body of 
 the same volume are called specific iceights. 
 
 " We say cork is a light, lead a heavy body, while we uncon- 
 sciously compare their absolute weight with their volume, ^i^aen we 
 
4 INTRODUCTION. 
 
 compare the weight of a volume of cork with a like volume of lead, 
 we perceive the difference which exists with respect to the mass of 
 both, tiiat is, their specific weight." * 
 
 21. The power of cohesion is that power upon which 
 depends the state (3) of a body. It acts between the 
 smallest particles of homogeneous bodies. f 
 
 22. The force which is necessary to separate the par- 
 ticles of a body is in proportion to the intensity of the 
 power of cohesion. 
 
 " The cohesive power of solid bodies, for example metals, is de- 
 termined by the weight which rods of a different metal are capable of 
 bearing." 
 
 23. In chemistry, the poicer of cohesion is that ten- 
 dency which the parts of a body evince to become solid, 
 or to maintain the state of solidity. The coherence of 
 a body depends upon this inclination. 
 
 24. The power of cohesion cannot be completely 
 overcome by mechanical means. By grinding, pound- 
 ing, &c., it is possible to change a great mass of sub- 
 stance into many smaller masses, but the smallest piece of 
 the pounded body is solid, that is, is coherent. 
 
 25. The power of cohesion acts not at great distances, 
 it is only evinced when the particles of a body are in 
 
 * Or Specific Gravity ; for the methods of taking specific gravities, 
 see Webster's Chemistry, 3d edit. p. 114. 
 
 t Homogeneous bodies are those which are composed of particles 
 of the same kind ; thus a mass of iron consists of particles of iron. 
 Each particle, however, may be a componnd ; thus in marble each 
 particle is a compound of lime and carbonic acid. When speaking 
 of the mass we say it is made up of homogeneous particles, and they 
 are held together by cohesion. 
 
 The constituents, which we obtain by chemical analysis, are of 
 different kinds, heterogeneous, and these are united by chemical at- 
 traction or affinity. 
 
DEFINITIONS. ELASTICITY. 5 
 
 immediate contact, or when the distance is so small as 
 not to be perceptible. 
 
 26. The limits of the power of cohesion between the 
 particles of solid bodies are denominated hardness and 
 softness. Ductile, tenacious bodies are so named, when 
 their particles can be extended in different directions, 
 through the employment of external force, and remain so 
 extended when the external force is discontinued. Brit- 
 tleness is the reverse of ductility. Elasticity is that 
 property of the particles of a body which allows them, 
 by pressure, to take another form, and, by the removal of 
 the pressure, to assume their original state. 
 
 27. In fluid bodies the power of cohesion is very 
 slight, it is only necessary to employ a small force to 
 separate their particles from one another. 
 
 28. Gaseous bodies possess not the slightest cohesion, 
 but their particles evince a tendency to repel one another ; 
 they extend themselves on all sides when this extension 
 is not prevented.* 
 
 29. This inclination of the particles of gaseous bodies 
 to repel one another is named the elasticity of gaseous 
 bodies ; it can be measured by the pressure which their 
 particles exercise on all sides. 
 
 30. The elasticity of gaseous bodies decreases in pro- 
 portion as their particles are separated from one another : 
 it increases inversely in proportion as they approach one 
 another. 
 
 31. The power of cohesion acts upon many gaseous 
 bodies, when they become condensed to a certain point, 
 that is, when their particles are only separated from one 
 
 * The term Gas is applied to all bodies when in the aeriform state. 
 By air is understood our atmosphere which consists of different gases. 
 1* 
 
6 INTRODUCTION. 
 
 another by a small distance ; in this case they lose their 
 gaseous form and become liquid.* 
 
 32. Gaseous bodies cease to extend themselves when 
 their elasticity is equal to the force, with which they are 
 attracted to the earth. 
 
 Gravitation acts upon the smallest particles of the gaseous bodies, 
 and endeavours to draw them to the centre of the earth, and of course, 
 to increase their density ; elasticity strives on the contrary, to remove 
 their particles from one another. As this tendency ceases with the 
 extension, there must exist a point where gravitation preponderates, 
 and at this point they must obey the laws of fluid bodies, that is, they 
 can no longer perfectly fill the vessel, in all directions, which contains 
 them, and their particles in a state of rest must take a horizontal sur- 
 face. — Faraday. 
 
 33. In Chemistry, that tendency of a fluid or solid 
 body, under certain circumstances, to take the gaseous 
 form, is often denominated, the elasticity of the body. 
 
 34. The faculty which a solid or liquid body possess- 
 es, of taking, under ordinary conditions, a gaseous form, 
 is named the volatility of this body. 
 
 35. Solid or liquid bodies which have become gase- 
 ous, are denominated vapors. 
 
 36. The tendency which fluid or solid bodies possess 
 of taking the gaseous form, and the pressure which their 
 vapors exercise on all sides, is denominated the tension 
 of these bodies. 
 
 37. Jlffinity. — When we bring two heterogeneous 
 bodies in contact with one another, they either lose their 
 properties or remain unchanged. 
 
 38. The reason why heterogeneous bodies change 
 
 * The pressure required to render gases liquid varies with each ; 
 thus carbonic acid requires a pressure of 540 lbs. at the temperature 
 of 32°. Ammonia about 97 lbs. at 50°. Nitrous oxide (the exhilar- 
 ating gas) 750 lbs. at 45°. See Webster's Cheviistry, p. 117. 
 
DEFINITIONS. AFFINITY. 7 
 
 their properties by contact, proceeds from a peculiar 
 power, different from the power of cohesion, and which 
 we name the poioer of affinity (21, note). 
 
 39. Chemical affinity acts between the smallest parti- 
 cles of heterogeneous bodies : its action is only percep- 
 tible when the bodies are in contact, that is, it acts at 
 infinitely small distances. 
 
 40. When the characters of two bodies become so 
 changed through chemical affinity, that a third, a new 
 body is formed, in the smallest particle of which, a 
 certain quantity of the two bodies (that were brought in 
 contact,) exists, the result is said to be a compound of 
 these bodies. 
 
 41. The new resulting body is named the product of 
 the combination. (The expression, compound, is more 
 generally given to the product of the combination of two 
 bodies.) 
 
 42. We say the body a possesses an affinity for the 
 body 6, when it can form a compound with the body b. 
 
 43. The bodies which exist in the compound, are 
 named the constituents of the compound. 
 
 44. When a solid unites with a fluid body, and the 
 product of the combination is fluid, the result is said to 
 be a solution. In a solution, the cohesive power of the 
 solid body is destroyed by the chemical affinity of the 
 fluid. 
 
 45. When a solid is not dissolved by contact with a 
 fluid body, they have either no affinity for one another, 
 or the cohesive power of the solid body is greater than 
 their reciprocal affinity. 
 
 46. The evolution of light and heat generally takes 
 place when a gaseous body unites with a solid or a fluid, 
 — that is, it produces fire. This species of chemical 
 combination is called a combustion. 
 
8 INTRODUCTION. 
 
 47. When two gaseous bodies unite with one another, 
 it follows, that their affinity is greater than their elasticity 
 (39) : in most cases they lose their gaseous state, and 
 become solid or liquid. Generally, gaseous bodies only 
 unite with one another through the action of other powers 
 or matters, by means of which, their elasticity is either 
 diminished or destroyed. 
 
 48. When a gaseous body unites with a solid or liquid 
 body, it happens that either the former loses its gaseous 
 state, and becomes in the new compound, solid or liquid; 
 or it retains its state, and in this case, the solid or fluid 
 body becomes gaseous. 
 
 49. When a solid or liquid body by combining with a 
 gaseous body, becomes itself gaseous, it follows, that its 
 affinity for the gaseous body is greater than its power of 
 cohesion. 
 
 50. When a gaseous body by uniting with another 
 body forms a solid or fluid compound, it follows, that its 
 elasticity is smaller than their mutual chemical affinity. 
 
 51 . The new properties which one body evinces when 
 brought in contact with another body, are denominated 
 the chemical properties of bodies. 
 
 52. The affinity of one body for another is either sus- 
 pended or diminished by every thing which prevents that 
 near approach necessary to the action of the power of 
 affinity. 
 
 53. Heat. — The most ordinary observation shows, 
 that a body can change its state without being brought in 
 contact with another, or without this change depending 
 upon chemical affinity. In all these cases, the change 
 of state depends upon the quantity of heat present in the 
 body. 
 
DEFINITIONS. HEAT. 9 
 
 54. Under the name of heat, caloric* is considered 
 an invisible, imponderable matter, which possesses the 
 property of penetrating every substance, and of forming 
 combinations with the same. 
 
 55. Heat always tends to leave a body penetrated 
 (heated) by this peculiar matter, (to become cold). A 
 body, which possesses less heat (which is colder) than 
 the surrounding bodies, always abstracts heat from those 
 bodies (that is, it becomes warmer). 
 
 56. That measure of heat which a body gives to or 
 takes from the surrounding bodies, is named its tempera- 
 ture. 
 
 57. The loss of heat which a hot body sustains, in- 
 creases with its temperature : that is, the hotter a body 
 is m comparison with the surrounding ones, the more 
 heat will it lose in the same time. 
 
 58. In order to heat a body to a certain temperature, 
 it is necessary to convey to this body a certain measure 
 of heat, so that it can give to another body a determinate 
 quantity of heat. 
 
 59. We say that a body is icarm, when it gives out 
 heat to our organs ; cold, when it abstracts heat. 
 
 60. We observe as the most general action of heat, 
 an increase of volume ; bodies extend themselves when 
 they become heated. Gaseous, fluid, and solid bodies 
 by the same increase of temperature undergo an unequal 
 extension of volume. The extension of gaseous bodies 
 is greatest ; and the extension of liquids greater than that 
 of solids. 
 
 * From the Latin, calor, heat. We have no evidence that caloric 
 is material ; some consider heat as depending upon a tremor or vibra- 
 tion excited in bodies. See Thomson on Heat and Electricity, 
 2d edit. 
 
10 INTRODUCTION. 
 
 Gl. The volume of a body, in most cases, increases 
 or diminishes, according to its temperature. (The more 
 that a body is heated, the greater is the increase in its 
 volume ; when a hot body is allowed to cool, it assumes 
 its original bulk, it contracts.)* 
 
 62. This contraction and extension are emploj'ed in 
 measuring the quantity of heat which a body has given 
 out to, or taken from, the surrounding ones. The instru- 
 ment employed for this purpose is named thermometer .\ 
 
 63. An ordinary thermometer is a narrow tube, in one 
 end of which a small ball is blown, and this is filled with 
 a fluid ; generally with mercury. | When the mercury 
 becomes heated in the ball, it extends ; and this exten- 
 sion is visible by the rise of the column of mercury in 
 the narrow tube. 
 
 64. When a thermometer is plunged in melting ice, 
 the mercury in the narrow tube stands at a certain point, 
 which remains always the same, under the same circum- 
 stances. At the level of the ocean, when placed in 
 boiling water, the mercury expands, and stands at another 
 point, which likewise never changes. 
 
 65. The space between these two fixed points is di- 
 vided into a certain number of equal parts, which are 
 named degrees. The division is denominated the scale 
 of the thermometer. Celsius divides this space into 100. 
 
 * Advantage is taken of this in the arts, as in applying the tire to 
 a wheel; the iron is heated, expanded, and applied, in cooling it con- 
 tracts and binds the wood work firmly together. 
 
 t From the Greek, signifying measurer of heat. These instru- 
 ments are too often incorn^ct. Those made by I. S. F. Huddleston, 
 185 Washington Street, Boston, may be recommended. 
 
 i For a more particular description of thermometers, see Webster's 
 Chemistry, p. 44. 
 
DEFINITIONS. THERMOMETER. 11 
 
 Reaumur into 80. Fahrenheit into 180. The point 
 Tiom which the division commences is named Zero.* 
 
 66. A body heated to 30° or 40° Celsius, signifies 
 that so much heat has been conveyed to it, that the mer- 
 cury of the centigrade thermometer has been extended 
 to this point, which, numbered from Zero, corresponds 
 to the oOth or 40th division of the scale of the ther- 
 mometer ; (86° or 104° F.) 
 
 67. The thermometer shows by the expansion or con- 
 traction of the mercury, when a body absorbs or gives 
 out heat ; hence, it does not show the absolute quantity 
 of heat which a body contains. 
 
 68. Free, sensible, thermometrical heat is that quantity 
 of heat which the mercury of the thermometer absorbs 
 or gives out, in order to extend or contract itself to a 
 certain point. 
 
 69. The extension of a body by heat, proves that its 
 particles are removed to a greater distance from one 
 another ; it is (according to 22) clear, therefore, that the 
 power of cohesion must become weakened. 
 
 70. When solid bodies become heated to a certain 
 point, their power of cohesion is so much weakened, 
 that their coherence ceases, and they become Jluid. 
 The point, at which solid bodies become fluid, is named 
 their fusing point, 
 
 71. When a fluid body is fully heated, the power of 
 cohesion of its particles is completely destroyed, and it 
 becomes gaseous. 
 
 72. By the abstraction of the heat, these bodies again 
 take their original state ; — the gaseous becomes a liquid, 
 and the liquid a solid body. 
 
 * The Zero in Celsius and Reaumur corresponds to 32" Fahrenheit. 
 
12 
 
 INTRODUCTION. 
 
 73. Vapors, in their restricted signification, are gaseous 
 bodies, which, by the ordinary temperature and pressure, 
 take again their original state. 
 
 74. Gaseous bodies are denominated gases, when they 
 preserve their state at the ordinary temperatures. 
 
 75. In order to heat different bodies to the same 
 temperature, it is necessary to have different quantities 
 of heat. The unlike quantity of heat, which like weights 
 of different bodies require, in order to possess the same 
 temperature, is named the specific heat of a body. 
 
 76. Through the union of certain conditions, whose 
 connexion is denominated an experiment, generally by the 
 mutual contact of bodies, with the application of heat, 
 from a great number of substances, others can be ex- 
 tracted of entirely different properties. 
 
 77. A limited number of bodies, however, suffer no 
 change when so examined. These are named simple 
 bodies, — chemical elements. At present fifty-five such 
 simple bodies are known, and, arranged alphabetically, 
 are as follows : — 
 
 Aluminum 
 
 Cobalt 
 
 Manganese 
 
 Sodium 
 
 Antimony 
 
 Columbium 
 
 Mercury 
 
 Strontium 
 
 Arsenic 
 
 Copper 
 
 Molybdenum 
 
 Sulphur 
 
 Azote 
 
 Fluorine 
 
 Nickel 
 
 Tellurium 
 
 Barium 
 
 Glucinum 
 
 Osmium 
 
 Thorium 
 
 Bismuth 
 
 Gold 
 
 Oxygen 
 
 Tin 
 
 Boron 
 
 Hydrogen 
 
 Palladium 
 
 Titanium 
 
 Bromine 
 
 Iodine 
 
 Phosphorus 
 
 Tungsten 
 
 Cadmium 
 
 Iridium 
 
 Platinum 
 
 Uranium 
 
 Calcium 
 
 Iron 
 
 Potassium 
 
 Vanadium 
 
 Carbon 
 
 Latanium 
 
 Rhodium 
 
 Yttrium 
 
 Cerium 
 
 Lead 
 
 Selenium 
 
 Zinc 
 
 Chlorine 
 
 Lithium 
 
 Silicon 
 
 Zirconium 
 
 Chromium 
 
 Magnesium 
 
 Silver 
 
 
 78. A compound body is formed by the union of one. 
 
DEFINITIONS. METALS. 13 
 
 two, three, or more, simple bodies ; the elements of a 
 compound are also named the heterogeneoii-i parts of a 
 body (21, note). A compound of one simple with 
 another simple body is called a binary compound : a 
 ternary contains three, and a quaternary four elements. 
 
 79. Compounds are divided into three classes. All 
 binary compounds belong to the first class. For exam- 
 ple : — Sulphuric acid, potash, alumina ; when one 
 binary unites with another binary compound, a binary 
 compound of the second class is formed, — as, sulphate 
 of potash. This class of compounds contains either 
 three or four elements. By the combination of a com- 
 pound of the second class, with another of the same 
 class, a compound of the third class is formed, — as, 
 alum, &c. The elements of the compounds in the 
 second and third classes, are also called the ultimate con- 
 stituents of the compound. 
 
 80. Two great groups are formed by comparing the 
 external characters of the elements. Those of one 
 group possess a metallic lustre, — those of the other group 
 not. The latter are sometimes named metalloids, the 
 former metals. 
 
 81. A combination of a body with oxygen, is called 
 an oxide ; with chlorine, a chloride ; with sulphur, a 
 sulphuret, he. 
 
 82. The oxides of chlorine, bromine, iodine, sulphur, 
 phosphorus, selenium, possess similar characters : they 
 are soluble in water. Their solution has a sour taste, 
 and changes the vegetable blues to red.* This class of 
 combinations is named acids. 
 
 * The blue liquor obtained by steeping purple cabbage leaves in 
 hot water is a convenient test liquor for acids and alkalies. 
 
 2 
 
14 INTRODUCTION. 
 
 83. The chloride, bromide, and sulphuret of hych'O- 
 gen, possess similar characters, and they are likewise de- 
 nominated acids ; but in order to distinguish ihem from 
 acids which contain oxygen, they are called hydrogen 
 acids. 
 
 84. Several metals, also, form acids with oxygen ; 
 but the greater number of metallic oxides, are, in their 
 relations, totally different from the acids. They form 
 compounds which, for the most part, are insoluble in 
 water ; those soluble in water have an alkaline taste, and 
 possess the property of restoring the blue color of vege- 
 tables, which have been reddened by acids. These also 
 change many vegetable yellows to red or brown. This 
 class is denominated bases^ and the soluble bases are 
 named alkalies. 
 
 85. The bases unite with acids, and the new com- 
 pounds which result, are termed salts. 
 
 86. The characters of the acids and bases, disappear 
 in the salts in such a manner, that both, when united in 
 certain relations, lose their property of changing the vege- 
 table colors. This state is said to be neutral. 
 
 87. Many salts redden vegetable blues, and others, 
 again, restore the blue color of vegetables, reddened by 
 acids : in the first instance, the salt possesses an acid, 
 and in the latter an alkaline reaction. 
 
 88. In general, that body is termed an acid, when it 
 has the property of destroying alkaline characters, al- 
 though only in one instance ; and it matters not whether 
 it reddens vegetable blues or not. On the contrary, that 
 body is termed a base, where it neutralizes the characters 
 of any acid, while it unites with the acid. 
 
 89. A simple body which is capable of forming either 
 an acid or a base, is termed a radical ; a compound 
 
AFFINITY. CRTSTALLIZATION. 15 
 
 radical consists of two or three simple bodies, and com- 
 ports itself in a similar manner to the simple radicals ; 
 that is, it is capable of forming acids and bases. 
 
 CHAPTER II. 
 
 AFFINITT. 
 
 Division I. — Crystallization. 
 
 90. When a fluid or gaseous body passes into the 
 state of a solid, the particles of the fluid or gaseous body, 
 possessing the greatest mobility, can follow, unrestrained, 
 the power of cohesion. It is remarked, in this case, 
 that the smallest particles of the body only attract them- 
 selves in certain determinate directions ; there are formed 
 regular, even-sided bodies, or crystals. The conversion 
 of a fluid, or gaseous body, into the state of a solid, is 
 termed crystallization. 
 
 91. All bodies, which can become fluid or gaseous, 
 without losing their chemical properties, can be crystal- 
 lized. 
 
 92. The regular forms which bodies take through 
 crystallization, can all be derived from a very small num- 
 ber of geometrical figures. The discussion of the con- 
 nexion of all crystalline forms is the object of crystal- 
 lography. 
 
 93. When the conversion of a fluid body into the state 
 of a solid is allowed to take place slowly and quietly, 
 the crystals are in proportion larger and more regular. 
 When the crystallization takes place rapidly, the crystals 
 
16 INTRODUCTION. 
 
 are small ; very often so small that the particular form 
 cannot be seen with the naked eye. 
 
 94. A solid body can be converted into a liquid, by 
 the application of heat (70), and by the chemical affinity 
 of another (44). Heat^ and chemical affinity^ are the 
 means by which bodies may be crystallized. It is a 
 necessary condition, in their employment, that the chemi- 
 cal properties of the bodies which are in contact do not 
 change. 
 
 95. When a fluid is brought in contact with a solid 
 body, if they have an affinity for one another, the fluid 
 will dissolve so much of the solid body as corresponds 
 with their mutual affinity. Beyond this limit, when the 
 circumstances are not changed, no further combination 
 takes place ; in this instance the solution is said to be 
 saturated. 
 
 96. When heat, and the chemical affinity of a body, 
 equally act upon a solid body, both endeavour to destroy 
 the cohesive power of the latter ; and it generally 
 happens, in this case, that the soluble power of the fluid 
 increases with its temperature. 
 
 " Many solids are more soluble in hot than in cold water." 
 
 97. The term, saturated, thus depends upon the tem- 
 perature of the fluid body ; a solution is said to be satu- 
 rated by ordinary temperatures, by 40^, or by a low 
 temperature. 
 
 98. All bodies are not dissolved without a change in 
 the composition, and it happens in many cases, that the 
 solubility of a body is the same in both cold and hot 
 flluids ; less often is the solubility smaller in a high tem- 
 perature than in a lower. 
 
 99. A saturated hot solution of a body, (whose solu- 
 
AFFINITY. CRYSTALLIZATION. 17 
 
 tion is greater in a high temperature) by cooling allows 
 that excess to precipitate, which the cold fluid could not 
 retain, — Crystallization by cooling. In proportion to 
 the difference of the solubility of a body at different 
 temperatures, the crystallization through cooling is easier. 
 
 100. Bodies which dissolve in cold and hot fluids, in 
 the same quantity, can be obtained in the state of crys- 
 tals, when by some means the dissolving fluid is re- 
 moved, — Crystallization, by means of evaporation, — 
 sloiv crystallization. The body can be crystallized, 
 either by cooling or evaporation, according to the nature 
 of the fluid employed in the solution. Common salt, 
 for example, can be crystallized from water by evapora- 
 tion, and from muriatic acid by cooling. 
 
 101. Besides the employment of fluids, as alcohol, 
 water, ether, mercury, &c., many bodies can be crys- 
 tallized by melting, and then allowing the melted mass to 
 cool. Regular crystals can be obtained in this manner, 
 when only part of the melted mass is allowed to become 
 solid, and then pouring off, at a certain temperature, what 
 remains liquid.* 
 
 102. There are bodies which crystallize equally well 
 in both ways. Sometimes the crystalline form of the 
 body is the same, after both methods, as common salt ; 
 and in other cases the shape of the crystals are so differ- 
 ent, that they cannot be derived from the same primary 
 form, as, for example, sulphur. 
 
 103. Bodies which crystallize in forms, incompatible 
 with one another, are named heteromorphous. 
 
 104. Many bodies, which possess a similar composi- 
 tion, have the same crystalline form. It generally hap- 
 
 * See Webster's Chemistry, paragraph 1139. 
 
 2* 
 
18 INTRODUCTION. 
 
 pens, in this case, that the crystalline form is dependent 
 upon the composition and the similarity of the chemical 
 properties of the constituents. 
 
 105. Two or more bodies of the same class, which, 
 when united with a third body, form a compound of the 
 same crystalline form, are denominated Isomorphous. 
 
 106. The external qualities of a body, form, transpa- 
 rency, hardness, &c., depend upon a certain position of 
 the particles of a body which is influenced by the power 
 of cohesion. Hence, it follows, if the particles of a 
 body are prevented taking that position in which they 
 form a regular crystal, when thus the directions are 
 changed in wdiich they are most powerfully attached to 
 each other, that the external characters of the body, in- 
 dependent of the chemical properties, will also be 
 changed. 
 
 107. Such solid bodies are called amorphous. 
 
 " Sulphur heated to 1G0°, and quickly poured into cold water, does 
 not crystallize ; it remains transparent, soft, and may be drawn out 
 into long threads. Barley-sugar is amorphous sugar ; crystallized 
 glass is opake, white and hard as flint ; the ordinary glass is amor- 
 phous. Sulphuret of antimony is a black powder, but when thrown 
 into water while red hot, it is of a red brown color. In many amor- 
 phous substances, barley-sugar, amorphous sulphur, &c , a change of 
 their characters takes place after some time ; perfectly transparent 
 amorphous sulphur becomes opake and hard, barley-sugar loses 
 its transparency, its fracture, which was conchoidal, appears then 
 even, and shows internally crystallized forms. These observations 
 prove the remarkable fact, that the smallest particles of a solid are, to 
 a certain extent movable ; agreeing also with the fact, that they are 
 not in perfect contact." 
 
 108. When many crystalline bodies become heated, 
 a remarkable appearance is observed, the crystal breaks 
 in all directions with a certain force, and is changed into 
 a more or less fine powder, — they decrepitate. This 
 
AFFINITY. — CRYSTALLIZATION. 19 
 
 phenomenon is thus explained ; these crystals expand 
 unequally in different directions, in one direction more 
 than another ; while thus, the smallest particles follow 
 in one direction, and not in the other, a separation of 
 the two is the result of the action of heat. It is remark- 
 ed sometimes with heteromorphous bodies, that the 
 smallest particles, after the decrepitation, assume an- 
 other form. 
 
 109. When a fluid is saturated at a high temperature 
 with a body, — for example, a salt, it still possesses the 
 property of dissolving other bodies, for which it has an 
 affinity. 
 
 110. When a crystal is placed in a fluid, super- 
 saturated with the same body, it begins to increase on 
 every side. (This appearance proves that an attraction 
 takes place between the crystal already formed, and 
 those parts which are being formed. 
 
 When we place in a saturated solution of two salts, a and b, a crys- 
 tal of the body a, the excess of the dissolving body a crystallizes first; 
 a similar effect is produced with the body h, when a crystal of b is 
 placed in the solution ) 
 
 111. When a saturated solution of two or more salts 
 has deposited crystals by cooling, each crystal contains 
 either an uncertain proportion of each of the dissolved 
 bodies, or the crystals merely lie near one other, with- 
 out being a mixture of the bodies which were dissolved. 
 
 The sulphates of copper, iron, and zinc dissolved together in hot 
 water, afford crystals which contain copper, iron, and zinc ; nitrate of 
 potash and carbonate of soda crystallize out of the same solution, but 
 merely lie near one another." 
 
 112. The fluid, from which crystals have been de- 
 posited, is denominated mother-ley as the mother-ley of 
 common salt, &c. 
 
20 INTRODUCTION. 
 
 113. Many crystals during their deposition, unite 
 with a certain portion of the fluid, which in tliis case, 
 becomes also solid. Crystals deposited from an aque- 
 ous solution and containing water, are said to contain 
 ivater of crystallization. In this case, it very often 
 happens that the form is dependent upon the quantity of 
 water of crystallization. 
 
 114. Many bodies which contain water of crystalli- 
 zation, lose either the whole or part of this water by 
 evaporation at the ordinary temperature. They lose 
 their regular form, become opake, or fall into a fine 
 powder. — Effioresccnce. 
 
 115. Many crystallized bodies, which contain this 
 water, when heated to a certain point, suddenly change 
 their form, and in this case, the change of the form de- 
 pends upon a certain loss in their water of crystalliza- 
 tion. 
 
 116. Many salts containing water, melt by the appli- 
 cation of heat, while they dissolve in their water of 
 crystallization. In this case, the solid water has be- 
 come liquid, and a part of the salt has dissolved in this 
 liquid water, while the other portion has been deposited 
 without water. 
 
 117. Most salts containing water lose this water by 
 the application of heat without melting, and lose at the 
 same time their transparency and form. When again 
 brought in contact with water, they form the compound 
 containing water, become solid and cohering while a 
 new crystallization takes place. 
 
 118. When a body becomes quickly solidified in its 
 solution, the particles of the surrounding fluid prevent 
 the deposited body from forming large crystals, which 
 appear then in the state of a fine powder. This species 
 
AFFINITY. CRYSTALLIZATION. 21 
 
 of ciyscallization is called precipitation and the deposit- 
 ed body a precipitate . 
 
 Exp Into a wine glass of lime water drop some oxalic acid, Si pre- 
 cipitate will subside, — oxalate of lime. 
 
 119. When in a compound of a fluid with another 
 body, the fluid becomes solid, its affinity for the dis- 
 solved material ceases and a separation of the two fol- 
 lows, (frozen wine, frozen vinegar, &c.) 
 
 120. A fluid, which contains foreign substances, can 
 only crystallize, when the cohesive power of its parti- 
 cles is greater, than its affinity for those bodies with 
 which it is in contact. 
 
 121. When a solid is only partially deposited from a 
 fluid, so that part remains dissolved, it follows, that the 
 affinity of the fluid body is not great enough to over- 
 come the cohesive power of the dissolved solid body. 
 In this case, by the addition of more of the fluid, the 
 whole can be retained in solution. 
 
 122. When a solid body is so deposited from a fluid 
 that nothing more remains in solution, they either have 
 no affinity for one another, or the cohesive power of the 
 particles of the solid body is greater than their affinity 
 to the fluid. 
 
 123. When a solution of a body A, is brought in 
 contact with the solution of another body B, it gener- 
 ally happens, that a new solid compound is deposited, 
 which contains A and B. The new compound arises 
 undoubtedly from the chemical affinity of the two bodies 
 A and B for one another, but their separation from the 
 fluid depends upon the predominating cohesive power 
 of the particles of the new formed body, that is, upon 
 their insolubility in this fluid. 
 
22 INTRODUCTION. 
 
 124. Hence, it follows, that when the nature of the 
 dissolving medium is changed, a body can be obtained 
 in the solid state without cooling and without evapora- 
 tion ; that is, it can be obtained crystallized when its 
 affinity for the new dissolving fluid is less than its cohe- 
 sive power. 
 
 Division II. — Combination. 
 
 125. The affinity of bodies is of different degrees. 
 
 126. The property which bodies possess of uniting 
 with one another, that is, their affinity is dependent 
 upon, (a) their state of cohesion, and (6) the tempera- 
 ture, in which both are brought in contact with one 
 another. 
 
 127. (a) Influence of the state of cohesion upon the 
 combination of bodies. Two bodies can only unite 
 with one another when the cohesive power of the par- 
 ticles of one or of both, is smaller than their chemical 
 affinity. 
 
 128. When two bodies combine with one another, 
 their particles must be easily movable, that is, they 
 must be capable of changing their situation, or otherwise 
 they cannot come in contact with each other. The first 
 most general condition, necessary to the formation of 
 a compound is, that the cohesion of one or boih of the 
 bodies must be overcome. This is accomplished either 
 by the melting or dissolving of one or both of the 
 bodies. 
 
 129. Two solid bodies of powerful affinity unite with 
 one another only when in contact, when the product of 
 the compound is solid, it follows that the particles of 
 
COMBINATION. INFLUENCE OF TEMPERATURE. 23 
 
 the intermediate compound prevent the perfect union of 
 the other imperfect combination (oxalic acid and lime). 
 
 130. When in the moment of combination of two 
 solid bodies, the new compound, or one of the constitu- 
 ents, becomes liquid, the combination of solid bodies in 
 these cases is perfect. As for example, salt and snow ; 
 copper and sulphur finely pounded, quickly mixed to- 
 gether become red hot, and sulphuret of copper results. 
 
 131. Gaseous bodies whose elasticity in the ordinary 
 state is greater than their affinity for solid or fluid 
 bodies, only unite with the latter, when brought in con- 
 tact with these in the moment of their separation from 
 other fluid or solid bodies, thus immediately before 
 taking the gaseous state ; status nasccns, nascent state 
 (sulphurets and acids, &c.). 
 
 132. (b) Injiuence of temperature upon the combina- 
 tion of bodies. It is clear that, by the change of the 
 state of a body by the action of heat, a great influence 
 must be exerted upon the play of affinity, while the 
 state of a body is changed, its cohesion is weakened in 
 a much greater degree than its affinity, and consequently 
 its action and its affinity are increased. In the combi- 
 nation of two bodies, heat acts not only upon the state 
 but also upon the affinity of both of the bodies. 
 
 133. When the distance of the constituents of a 
 compound, or the elasticity of one of the constituents, 
 by the action of heat, becomes greater than the sphere 
 of chemical affinity, the constituents will separate. 
 
 134. Hence, it follows, that two bodies possessing 
 an equal affinity for each other cannot unite at a tem- 
 perature, where their elasticity, or the distance of their 
 particles is greater than the sphere of their attraction. 
 
 135. Increase of the degree of affinity. The affinity 
 
24 INTRODUCTION. 
 
 of two bodies is in some cases increased by the contact 
 of a tliird, which unites with neither and possesses no 
 affinity for the new compound, as platina, hydrogen, 
 and oxygen. (See "Webster's Chem. parag. 1287). 
 
 136. In all cases the affinity of two bodies is increas- 
 ed by the contact of a third, which possesses an affinity 
 for the new resulting compound. Predisposing affinity. 
 
 137. Intimacy of chemical combination. From the 
 variation of the influence, which heat and the power of 
 cohesion exert upon chemical affinity there cannot exist 
 a general measure of the intensity of affinity, and for the 
 intimacy of chemical combination. 
 
 138. It is only in some cases that an approach can 
 be made in measuring the intimacy of a compound of a 
 body A, with others B, C, D, E, &c., through the dif- 
 ferent temperatures which are necessary to destroy the 
 compounds AB, AC, AD, &c. Carbonates of magne- 
 sia, lime, barytes, &c. 
 
 139. The strength with which a body a is united to 
 another, b, depends not only upon the intensity of their 
 affinity, but also upon the mass of one or other of the 
 bodies. 
 
 140. In a compound abb, a is more strongly attract- 
 ed, than in the simple compound ab, when the mass of b 
 is only half that in the former abb. 
 
 141. Hence it follows, that in the compound abb, b 
 is more weakly combined than in ab, because the mass 
 of a in the latter is greater than in the former. 
 
 142. When a body a is brought into contact with two 
 bodies, b and c, which both possess an affinity for it, a 
 is divided between b and c thus 
 
 A 
 
 B C 
 
DECOMPOSITION. 25 
 
 The proportion of a, which is united with h and c, de- 
 pends upon the degree of their affinity to c, and upon 
 the quantity of b and c which are present. Let the 
 affinity of h for a be as 5, that of c as 3, all other 
 things equal ; a (= 8a) is divided between h and c in 
 this proportion, 
 
 A 
 
 aaaaa 
 
 B C 
 
 143. When the quantity of c is enlarged, its affinity 
 for a increases ; but this increase of affinity is not pro- 
 portionate to the increase of quantity ; it is less. Let 
 the quantity of c be doubled in the above example, and 
 it will be found that 3 a are not abstracted from 6, but 
 less. Say that its affinity is increased ^, it follows that 
 h and cc equally divide a (=: 8a.) 
 
 A 
 
 aaaa aaaa 
 B CC 
 
 Division IIL — Decomposition. 
 
 144. When a third body c, is brought in contact with 
 a compound a6, the chemical characters in the com- 
 pound are either changed or not. In the first instance, 
 the result is said to be a decomposition of the compound 
 ab. Decomposition is divided into (r?) total and (6) 
 partial. 
 
 145. The decomposition of the compound ab by c is 
 said to be total, when the affinity of the body c to one 
 
 3 
 
26 INTRODUCTION. 
 
 of the constituents of the compound ah is such, that a 
 new compound be is so formed, that all b is united with 
 c, and the constituent a perfectly separated. 
 
 AB 
 
 A B 
 
 aaaaaa bbbbbb 
 
 cccccc 
 C 
 
 BC 
 
 146. The total decomposition of a compound by 
 means of the affinity of a third body very seldom takes 
 place. 
 
 147. When the decomposition of a compound takes 
 place in a solution, the result is said to be a decomposi- 
 tion by the moist way. Decomposition by the dry way 
 occurs by the action of substances upon one another at 
 a high temperature. 
 
 148. The total decomposition of a compound de- 
 pends generally upon the quantity^ and the state of the 
 substances acted upon, the temperature and the nature 
 of the fluid in which the decomposition takes place. In 
 most cases, the decomposition is only partial, and be- 
 comes total only under certain conditions. 
 
 149. Laws which regulate the partial decomposition 
 of a compound. — When a compound ab is brought in 
 contact with another body, c, which possesses an affini- 
 ty for 6, the two bodies a and c divide b between them, 
 and two new compounds ab and be are formed. This 
 division takes place in the way described in (143 and 
 145). 
 
 150. Let a =. Sa, h = Sb, c = 8f, and further, let 
 affinity and quantity, (cohesion and temperature) be 
 equal, it will be found that each of the new compounds 
 contains the same proportion of b. 
 
DECOMPOSITION. — LAWS. 27 
 
 B 
 
 I aaaa 
 
 AB < aaaa 
 
 ( hhbb 
 
 A 
 
 hbbh ) 
 
 cccc > BC 
 
 cccc ) 
 C 
 
 The one half of a (aaaa), is united with the half of 6 
 (bbbb), and the remainder of a (aaaa) is disengaged and 
 remains in the fluid : the same is the case with c, one 
 half of which is likewise uncombined. 
 
 151. The free portion of a (aaaa), and c {cccc) are 
 not inactive in the mixture ; the free a (aaaa) constant- 
 ly strives to decompose the compound be, and on the 
 other hand, the free c (cccc) endeavours to unite with 
 one of the elements of the compound ab. The decom- 
 posing action of the two free bodies remains in equilib- 
 rium, — that is, no further decomposition takes place. 
 
 152. When the free cccc are taken away, the equilib- 
 rium is destroyed ; the free aaaa share with 
 
 ] 7/77 of the compound < according to (142) 
 
 and there will be found in the mixture, free aa and cc. 
 B B 
 
 bb bb bbbb bbbb 
 
 aaaa cccc aaaaaaaa cccc 
 
 AC AC 
 
 153. When the free cc are being continually remov- 
 ed, a new division takes place, till a total separation of 
 the body c results. On the other hand, the same result 
 takes place with the body a, when a part of the same is 
 removed. 
 
 154. By the addition of c to a compound ab, a portion 
 of b is withdrawn, and a new compound be formed. If 
 
28 INTRODUCTION. 
 
 the quantity of c be double, a further decomposition of 
 the remaining ah is found to take place. 
 
 155. In proportion as h is withdrawn from a com- 
 pound aJ, the mass of a increases in proportion to the 
 mass of 6, with which it remains combined ; conse- 
 quently the affinity of a to 6 increases in the same pro- 
 portion as the quantity of b diminishes. (139, 140.) 
 Hence, it follows, that a compound nb can never be to- 
 tally decomposed by the increase of the quantity of a 
 third body c. 
 
 156. These laws, as above explained, which regulate 
 the decomposition of a compound, only take place when 
 the state of the bodies acting upon one another and the 
 state of the new resulting compound are the same. 
 They undergo a great change when the ordinary state 
 of one of the constituents of the compound, is different 
 from the state of the other third body^ or from the state 
 of the new compound. 
 
 157. When a body c acts upon a compound a5, and 
 the ordinary state of the body a is gaseous, a total de- 
 composition of the compound ab results, with the per. 
 feet separation of the body a (145). For example, 
 carbonate of lime and sulphuric acid. 
 
 158. The elasticity of the body a increases in this 
 case the affinity of the body c, as in (153) when one of 
 the elements is being continually removed out of action. 
 When the body a is prevented taking the gaseous state, 
 a partial decomposition only occurs. 
 
 159. In (157) suppose the body a not to be gase- 
 ous at the ordinary temperature, but to take this state at 
 120° C, it will so happen that at the ordinary tempera- 
 ture a partial decomposition only takes place, but at 
 120'^ it will be total. For example, acetate of potash 
 
DECOMPOSITION. 29 
 
 and sulphuric acid. Nitrate of potash and sulphuric 
 acid. 
 
 160. According as the quantity of the third body c 
 is greater or smaller, the decomposition of the compound 
 ah is more or less perfect. Hence it follows : when 
 the. state and mass of the bodies acting upon one another 
 can he changed by some temperatures .^ the decomposition 
 is also changed, for it either takes place, or vice versa. 
 As peroxide of iron heated to redness under a stream of 
 hydrogen produces iron and water ; iron heated to red- 
 ness in aqueous vapor, produces oxide of iron and hy- 
 drogen. Carbonic oxide and peroxide of iron, afford 
 iron and carbonic acid ; iron and carbonic acid afford 
 carbonic oxide and oxide of iron. Sulphuret of anti- 
 mony and hydrogen, give antimony and sulphuretted 
 hydrogen ; sulphuretted hydrogen and antimony give 
 sulphuret of antimony, and hydrogen ; potassium and 
 peroxide of iron, iron and potash. 
 
 161. The nature of the fluid in which the decomposi- 
 tion takes place has an important influence on the result 
 of the decomposition. A total decomposition occurs, 
 
 I. When the body a of the compound ab is insoluble 
 in the fluid, vjhile the compound be is soluble, as in 
 (145 and 123). 
 
 II. When the new compound be is insoluble and the 
 body a soluble in the fluid, as in (123) as nitrate of 
 baryta and sulphuric acid. 
 
 162. (From 159 and 161,) it follows, that the result 
 of the decomposition is changed according as it is ac- 
 complished by the moist or dry way ; or according as 
 the cohesive power or elasticity of one or the other 
 bodies acts in preponderance. 
 
 3* 
 
30 INTRODUCTION. 
 
 For example, — boracic acid is perfectly separated from all its com- 
 pounds by weak acids in the moist way; but in the dry way, it resists 
 the strongest acids. In the moist way, sulphuric acid decomposes 
 phosphate of lime, but in the dry way, phosphoric acid decomposes the 
 sulphates, &c. 
 
 163. It follows, further, That the result of the de- 
 composition changes with the nature of the fluid (122). 
 
 164. When two compounds, AB and DC, are 
 brought in contact with one another, and their constitu- 
 ents possess an opposite affinity for one another, a dou- 
 ble decomposition takes place. 
 
 165. When state and solubility are equal and the 
 :affinity different, the decomposition is only partial ; and, 
 in this case, the mixture will contain four compounds 
 A B, AD, DC, and C B. A solution of sulphate of 
 peroxide of iron, mixed with acetate of potash, is col- 
 ored dark brown ; sulphate of lime, in contact with 
 common salt, dissolves in a larger quantity than in 
 water. 
 
 166. When the state or solubility of the constituents 
 of the compounds A B and D C are different, or the 
 state and solubility of one or other of the new resulting 
 compounds is also different, a partial or total separation 
 of one, or of both, takes place. 
 
 167. These decompositions are modified, or changed 
 according to the temperature and the nature of the fluid, 
 in which the decomposition takes place (158, 159, 160, 
 161). 
 
DECOMPOSITION. 31 
 
 " For example, nitrate of lime and carbonate of ammonia, at the 
 ordinary, and at a high temperature." 
 
 168. The decomposition of a compound, A B, by 
 a third body, C, whose affinity for the constituent B, 
 is less than that of A for B, can be assisted by means 
 of a fourth body, D, which possesses an affinity for A. 
 For example, alumina is not decomposed by means of 
 carbon and chlorine taken separately, but acting to- 
 gether, there result carbonic oxide and chloride of 
 aluminium. 
 
 169. Predisposing affinity (136) effects also a change 
 upon the nature of the decomposition. 
 
 170. Laws which regulate the decomposition of triple 
 compomids, by heat and the predisposing affinity. When 
 a compound, containing three or more elements, is de- 
 composed at a great heat, the constituents unite in 
 new relations, forming new compounds, which are not 
 decomposed by the temperature in which they were 
 formed. 
 
 171. When a compound of three or more elements 
 is exposed to a great heat, in contact with another com- 
 pound, which possesses the property of forming with 
 two of the elements of the former, a new compound, 
 capable of resisting the action of heat, the remaining 
 constituents will form one or more new gaseous combi- 
 nations. 
 
32 INTRODUCTION. 
 
 CHAPTER III. 
 
 LAWS OF CHEMICAL PROPORTION. 
 
 172. 1. Law deduced from Experiment. The 
 quantity of A, which unites with B, in order to form 
 the compound A B, is invariably the same, perfectly 
 unchangeable. 
 
 "Under all conditions, water contains 88.91 oxygen, and 11.09 
 hydrogen ; or 100 oxygen, and 12.479 hydrogen ; or 1 oxygen, and 8 
 hydrogen. Sulphuric acid contains 40.14 sulphur, and 59.86 oxygen ; 
 or 201.17 sulphur, and 300 oxygen ; or 16 sulphur, and 24 oxygen." 
 
 173. 2. Law deduced from Experiment. When a 
 body, A, unites with another, B, in several propor- 
 tions, the quantity of B, in the second degree of com- 
 bination, is double that in the first, three times that in 
 the third, four times greater in the fourth, &c. 
 
 A-f B 
 
 1st 
 
 degree 
 
 of combination 
 
 B = l 
 
 A + BB 
 
 2d 
 
 « 
 
 (< 
 
 B = 2 
 
 A + BBB 
 
 3d 
 
 n 
 
 a 
 
 B = 3 
 
 A + BBBB 
 
 4th 
 
 (I 
 
 <( 
 
 B = 4 
 
 A + BBBBB 
 
 5th 
 
 a 
 
 (( 
 
 B = 5 
 
 For example, the degrees of oxidation of azote, (nitro- 
 gen,) sulphur, &c. 
 
 Or the relation is as follows : — 
 
 AA + BBB; A:B 
 
 AA + BBBBB ; A : B 
 
 AA 4- BBBBBBB ; A : B 
 
 2: 3 
 2:5 
 2:7 
 
 174. 3. Law deduced from Experiment. The quan- 
 tities in which bodies unite among one another, are pro- 
 portional. 
 
 175. When a certain quantity of body, A, unites 
 
LAWS OF CHEMICAL PROPORTION. 33 
 
 with 3 B, and 4C, and when B and C combine with 
 another D, the quantities of B and C, which unite with 
 D, are in the proportion of 3 to 4. 
 
 176. If 3 lb A unites with 5 lb. B, and 5 lb. B 
 with 2 lb. C, it will be found that 3 lb. A will most 
 accurately combine with 2 lb. C : that is, when both 
 can enter into combination with one another. 
 
 A : B : : 3 : 5 
 B : C : : 5 : 2 
 
 A : C : : 3 : 2 
 
 177. If the combining proportion of A, which unites 
 with B and C, be known, it follows clearly that the 
 combining portion of B, which unites with C, is also 
 known. 
 
 178. When 10 A, unite with 3 B, 6 C, 5 D, 7 E, 
 &c., it will be found that 3 B, unite accurately with 
 
 6 C, to 9 B C ; 6 C, with 5 D, to 1 1 C D ; 3 B, with 
 
 7 E, to 10 B E, &c. : it, of course, being understood, 
 
 that they possess an affinity for one another : 
 
 A : B : : 10 : 3 
 A : C : : 10 : 6 
 A:D::10:5 
 A : E : . 10 : 7 
 
 B : C ; D : E : : 3 : 6 : 5 : 7 
 
 179. Consequently, if the combining proportion of 
 one body, for example, oxygen, which unites with all 
 others, be known, the numbers which are found will 
 express, — 
 
 1. The combining proportion in which they unite 
 with oxygen ; and, — 
 
 2. The combining proportion in which they unite 
 among one another ; it being, of course, understood 
 that they possess an affinity for each other. 
 
34 INTRODUCTION. 
 
 By this, and similar methods, the combining numbers 
 of bodies have been obtained, of which tables will be 
 found in modern chemical works. 
 
 180. These numbers thus denote the weight of the 
 different substances tchich enter into combination with each 
 other ; they have received the name of chemical propor- 
 tions. 
 
 181. These numbers have also received the name of 
 equivalents. 
 
 " Therefore, in order to separate one of the constituents of a com- 
 pound, as for example the potassium from the compound of this sub- 
 stance with oxygen, by silver, sulphur, or hydrogen, &c., it is only ne- 
 cessary to replace 1 equivalent of potassium by 1 equivalent of silver, or 
 1 equivalent of sulphur, or hydrogen, &c. And on the other hand, to 
 separate the oxygen in the same compound by sulphur, chlorine, 
 iodine, bromine, »&c., all that is necessary is to have for every 100 
 oxygen, 1 sulphur, 1 chlorine, 1 bromine, 1 iodine." 
 
 182. Hence, the equivalent of a simple body is that 
 combining proportion of the body lohich is necessary to 
 unite with 1 sulphur, 1 chlorine, 1 silver, 1 potassium, 
 ^c, in order to form a compound. 
 
 183. When a body unites with oxygen in more pro- 
 portions than one, its true equivalent is doubtful. 
 
 In order to remove this doubt, it has been agreed to con- 
 sider that number the equivalent of the body, which unites 
 with 100 oxygen in the loioest degree of oxidation. 
 
 184. When one or more equivalents of a simple body 
 A, unite in more proportions than one with another body 
 B ; the quantities of B will be found to be multiples of 
 the equivalent of B expressed in whole numbers. 
 
 185. The number of the equivalent of a compound 
 body is the sum of the numbers of the equivalents of its 
 constituents. 
 
 186. When one compound body unites with another, 
 
LAWS OF CHEMICAL PROPORTION, 35 
 
 it is always in that combining proportion whicli expresses 
 the numbers of their equivalents. 
 
 187. The doctrine of proportion thus enables us to 
 designate more distinctly the most important classes of 
 certain chemical compounds, already noticed. 
 
 188. We understand under the term oxygen acids^ 
 compounds of metalloids with oxygen, in which one or 
 two equivalents of the radical are united with two or 
 more equivalents of oxygen. The higher degrees of 
 oxidation of many of the metals are also acids. 
 
 189. Oxygen bases are, without exception, compounds 
 of metals with oxygen ; many of which unite with oxy- 
 gen in more proportions than one, and others merely 
 have one degree of oxidation ; it has been agreed to 
 consider the lowest degree of oxidation as a compound 
 of one equivalent oxygen and one equivalent metal, cop- 
 per and mercury, &c., excepted, 
 
 190. JSCeutral salts are compounds of one equivalent 
 acid and one equivalent base. 
 
 191. With those acids, the equivalent of whose radi- 
 cal is doubtful, that quantity is taken as the equivalent 
 which is contained in an equivalent of their oxygen acid. 
 
 192. By the term equivalent of an acid, is under- 
 stood that quantity of the acid which possesses the prop- 
 erty of neutralizing one equivalent of any base, which 
 contains 100, that is, one equivalent of oxygen. 
 
 193. The equivalent of a base is that quantity which 
 unites with an equivalent of any acid, in order to form a 
 neutral salt. 
 
 194. As the equivalent of a compound body is the 
 sum of the equivalents of its elements, it is easy, when 
 the number is known, to calculate the number of the 
 equivalents of each of the constituents, from the known 
 composition of the body. 
 
36 INTRODUCTION. 
 
 195. When the sum of the number of the equivalents 
 of the constituents of a compound, that is, the equivalent 
 of a compound, is unknown ; the number of the equiva- 
 lents of the constituents is doubtful. Their relation, 
 however, can be found, if the quantity of the constituents 
 which has been determined by analysis in a certain weight 
 be divided by the equivalent of the constituents. 
 
 196. In all cases, the new products contain the sum 
 of the equivalents of the elements out of which they 
 have been formed, and this relation can always be ex- 
 pressed in equivalents. 
 
 CHAPTER IV. 
 
 THEORY OF CHEMICAL PROPORTIONS. 
 
 197. The laws according to which bodies combine, 
 have been deduced from an accurate comparison of the 
 composition of the compounds, and the phenomena 
 which they present when mutually decomposed. These 
 laws are expressions for facts, whose unchangableness 
 and truth are opposed by no kind of experience. Chemi- 
 cal proportions are independent of every theory, and 
 stand in no relation to any hypothesis. 
 
 The object of the science is not merely to confirm 
 the truth of chemical proportions, but to search and in- 
 vestigate the causes of their regularity and constancy. 
 
 It is clear, that these causes stand in the most intimate 
 relation with the physical constitution of the bodies, but 
 sense and experience desert us when we attempt to 
 fathom the ultimate causes of these phenomena. As 
 
THEORY OF CHEMICAL PROPORTIONS. 37 
 
 these ultimate causes are not appreciable by our senses, 
 ihey are consequently unknown, and for the most part 
 inscrutable. Hence, at this point, experimental philoso- 
 phy ceases and abandons the explanation to the imagina- 
 tion. If a law of nature, with all its consequences, or 
 a series of phenomena explained consecutively be op- 
 posed by no experience, no fact, the connexion of the 
 explanation with the phenomena is called a theory. The 
 naturalist infers from the laws of nature, from the phe- 
 nomena, their causes, and by a series of syllogisms he is 
 led to an explanation of the phenomena, or in other 
 words, to a theory. When two theories proceed from 
 different or opposite conceptions of the facts of the phe- 
 nomena, and both explain all facts and phenomena, it is 
 doubtful which to adopt. When a series of phenomena 
 are explained by only one theory, and when no single 
 fact or experience opposes the same, there is every 
 reason to believe, that this theory is the expression of 
 the true cause of the phenomena. 
 
 Hence, it follows, that the existence of such a reason 
 cannot be denied, because the eyes cannot perceive and 
 the hands cannot grasp it. No human eye has seen sound 
 or the waves of light, yet their existence depends on 
 syllogisms, demonstrated by numberless analogies. 
 
 It is less to be denied, because it is impossible to un- 
 derstand, how and in what manner the senses act. How, 
 and in what way light produces warmth ; /lOJt;, and in 
 what way heat boils water ; /iot<;, and in what gravity acts 
 at such distances ; hoio the affinity of two bodies mutu- 
 ally destroys the characters of both ; all is unknown. 
 
 198. A view of the physical constitution of bodies, 
 first propounded by Dalton, agrees so perfectly with all the 
 phenomena, which composition and decomposition pre- 
 4 
 
38 INTRODUCTION. 
 
 sent, and such numberless analogies prove the same, that 
 at present it must be regarded as the true expression of 
 the reasons of chemical proportions. 
 
 Atomic Theory. 
 
 199. According to this view, matter is not infinitely 
 divisible, but there exists a limit beyond which the par- 
 ticles of a body cannot be further divided. These 
 smallest indivisible portions of matter are denominated 
 atoms ; and it is further believed, that the atoms are un- 
 equally heavy. A body A consists of a number of in- 
 finitely small imperceptible particles A, and a body B of 
 a certain number of atoms B. 
 
 200. When a body A possesses an affinity for a body 
 B, the combination takes place so that the smallest par- 
 ticle (atom) of A unites with the smallest particle (atom) 
 of B. 
 
 When one body unites with another in more propor- 
 tions than one, the smallest particle of A combines with 
 2, 3, or 4, &c., of the smallest particles of B. If it 
 were possible to know the number of the atoms of a 
 body, or to weigh the smallest particles, nothing could 
 be easier than to determine the weight of a compound 
 atom, but a single atom is infinitely small and not appre- 
 ciable by the senses. 
 
 We know, however, that A and B, for example, unite 
 together by weight, in the proportion of 3 : 5. It is 
 clear, therefore, in the supposition, that the compound 
 A B, contained a certain number of the atoms of A, 
 and the same number of the atoms of B, that the relation 
 3 : 5 must express the due relative weight of the atoms 
 A and B. The compound A B contains 100 atoms of 
 A, and 100 atoms of B : the quantity of A weighs 5 
 
ATOMIC THEORY. 39 
 
 grains, the quantity of B, weighs 3 grains ; hence, 1 
 atom of A (100 atoms of A weigh 5 grains, how much 
 1 atom) := yf gf^'n? ^^d one atom B yl^. Let the 
 number of atoms of A and B, in the compound be 
 equally great, but unknown, the relation by weight of 
 5 : 3 never changes ; it matters not, how great or how 
 small, the number of the atoms may be, if the atom of 
 A weighs 5, the atom of B must weigh 3. The weight 
 of 3 of the atom of B infers the weight 5 of the atom 
 of A, and vice versa. These numbers, then, do not 
 express the absolute, but the relative weight, merely of 
 the atoms. 
 
 1000 oxygen unite with 128 hydrogen, to form 1125 
 water ; this relation by weight is as 1 : 8. If, now, 
 water consists of the same number of atoms of oxygen 
 and hydrogen, the weight of the atom of hydrogen will, 
 in all cases, be 8 times smaller than the weight of an 
 atom of oxygen. 
 
 201. The reason why bodies only unite together in 
 certain weights, in order to form compounds, that unlike 
 weights of the same mutually replace one another, that 
 bodies do not unite in all proportions, is thus explained 
 by the view, that matter exists in the form of particles, 
 not further divisible, but whose weights are different. 
 There is no other supposition, which offers a more prob- 
 able explanation, than the present. 
 
 202. (1.) Gaseous bodies unite with one another, 
 so that 1 volume of the one gas is combined with 1 vol- 
 ume, 2 volumes, or 3 volumes, &c., of the other gas. 
 
 (2.) The volume of the compound stands in a simple 
 relation to the volume of the constituents. 1 volume 
 oxygen, with 2 volumes hydrogen =i 3 volumes togeth- 
 er, and produce 2 volumes of aqueous vapor. 
 
40 INTRODUCTION. 
 
 1 vol. oxyg. with 2 vol. az. = 3 vol. produce 2 vol. protox. of az. 
 1 " az. " 3 " hy. = 2 vol. " 2 " ammon. gas. 
 
 1 " sulph. " 6 " hy. = 7 vol. «' 6 " sulphd. hydro. 
 
 1 " chlor. " 1 " hy. =^ 2 vol. " 2 " muriatic acid. 
 
 (3.) When one gas unites with another, in more pro- 
 portions than one, the volumes of this gas stand in the 
 same simple relation to one another, as the weights of 
 the atoms. 
 
 2 vol. azote, unite with 1 vol. oxygen, to protoxide of azote. 
 2 " " " 2 " " deutoxide of azote. 
 
 2 " '' " 3 " " hyponitrous acid. 
 
 2 " " " 4 " " nitrous acid. 
 
 2 " " " 5 " " nitric acid. 
 
 We observe, that, by the combination of two gases, 
 in all cases, the volume of the compound is either the 
 same as the volume of the constituents, or a condensa- 
 tion takes place. Hence, it follows, — 
 
 203. *^ volume of a compound contains either one 
 volume of each of its constituents^ or a multiple, or sub- 
 multiple of one or more of the constituents. 
 
 204. It is evident, that the laws of the combining 
 proportion of gaseous bodies can be derived from the 
 volume in which they unite, with even as much accura- 
 cy, as by means of the balance. In this point of view, 
 the knowledge of the specific weights of simple and 
 compound bodies, in the gaseous state, is one of the 
 most important means, to submit to the sharpest proof, 
 the constitution of compounds obtained by other meth- 
 ods. 
 
ATOMIC WEIGHT AND VOLUME. 41 
 
 CHAPTER V. 
 
 CONNEXION BETWEEN THE ATOMIC WEIGHT AND 
 VOLUME OF A BODY. 
 
 205. It has been already remarked, that the com- 
 pression of solid and fluid bodies, their elasticity, and 
 Other characters, have given rise to the opinion, that 
 their smallest particles, the atoms, are not in perfect 
 contact, but at certain distances from one another. 
 This distance increases when the body is heated ; it be- 
 comes smaller when the atoms are exposed to a certain 
 pressure. Solid and fluid bodies expand unequally 
 when heated, and the diminution of the volume by equal 
 pressure is also very different. From these facts, it 
 has been concluded, that the distances of the atoms of 
 solid and liquid bodies is not the same in all. This 
 inequality is not noticed in gaseous bodies ; all gases 
 expand equally, for the same degree of heat, and their 
 volume increases or diminishes equally for the same 
 pressure. From these facts, the conclusion has been 
 drawn, that the constitution, of gases is perfectly the 
 same ; that the atoms of gases are, in all, equally distant 
 from one another. Hence, it evidently follows, that 
 tivo gases of the same volume contain the same number 
 of atoms. When this proposition is regarded as true, 
 the numbers which express the equivalent of hydrogen, 
 azote, and some other bodies, are not the relative weights 
 of the atoms of the same. 
 
 2 volumes hydrogen unite with 1 volume oxygen. 
 
 Hydrogen. Oxygen. 
 
42 INTRODUCTION. 
 
 206. It is clear, when the gases of the same volume 
 contain the same number of atoms, that 2 or 3 volumes 
 of a gas must contain 2 or 3 times more atoms of the 
 same. In water, 100 oxygen combine exactly with 
 12.479 hydrogen ; the volume of hydrogen, as gas, 
 amounts exactly to twice the volume of oxygen, whence 
 it follows, that 12.479 hydrogen express the weight of 
 2 atoms of hydrogen, and 1 atom thus will weigh J-^^-i^ 
 = 62.395. 
 
 207. The specific weights of the gases are their rela- 
 tive weights by equal volume ; whence it follows, if the 
 above proposition be regarded as true, that the true 
 atomic weights of bodies must be proportional to their 
 specific weights when in the state of gases. 
 
 The theory of volumes presents some conveniences 
 in judging of the composition of those compounds which 
 are gaseous, or which can take the gaseous state. The 
 specific weight of the same is the sum of the specific 
 weights of the constituents in one volume, and the rela- 
 tion of the volumes of the constituents accurately ex- 
 presses the relative number of the atoms in the com- 
 ,pound. 
 
 CHAPTER VI. 
 
 ISOMORPHISM, OR THE CONNEXION BETWEEN THE EX- 
 TERNAL FORM AND THE CHEMICAL COMPOSITION OF 
 BODIES. CATALYTISM. 
 
 208. In many chemical compounds one constituent 
 can be partially or wholly taken away, and replaced par- 
 tially or completely by another body, while the external 
 
ISOMORPHISM. 43 
 
 form and its proportion of water (if it contains water of 
 crystallization) remain unchanged. 
 
 209. Those bodies or compounds which possess the 
 property of mutually replacing one another in combina- 
 tions, without changing the/orm of the same, are called 
 isomorphous substances (from I'aog, like, and ^oQcp^, form). 
 
 All the constituents of compounds are not isomor- 
 phous, when the compounds possess the same form 
 (arsenious acid and alum possess the same form, but the 
 constitution is quite different) ; and all compounds simi- 
 larly constituted do not possess the same form, (the form 
 of the chlorate is different from that of the nitrate of 
 potash). 
 
 210. When we endeavour to form a clear conception 
 of the reasons, that two bodies possess the same form, 
 that the same two bodies form combinations of similar 
 constitution, and these compounds also possess similar 
 forms, there remains no other way but to seek these 
 reasons, in the similar form of their smallest particles, 
 and in the similar positions which they take in their com- 
 binations. This leads most naturally to the existence 
 of atoms and may be employed as a proof that the atom- 
 ic theory is something more than a mere conception 
 formed, in order to explain a series of phenomena. 
 
 211. We regard in this work, the connexion of the 
 external form with the chemical constitution as the 
 surest guide to instruct us respecting the chemical con- 
 stitution of compounds. 
 
 212. Tivo elements of similar form produce coynbina- 
 tions of similar form, when these contain a like number 
 of atoms arranged in the same way. 
 
 213. A compound which is isomorphous with one or 
 
44 INTRODUCTION. 
 
 more others, possesses a similar composition and contains 
 a like number of atoms of the constituents. 
 
 214. We employ the atomic numbers, in order to 
 express the composition of bodies, in a short, easy, and 
 intelligible manner. It would be impossible to retain, 
 in the memory, the numbers which express the compo- 
 sition of compounds in two parts. The simple relation 
 in which bodies unite, according to their atomic weights, 
 is remembered with the greatest ease.* 
 
 Catalytism. 
 
 215. The decomposition of chemical compounds 
 generally takes place by the action of other bodies, in 
 such a manner, that the acting body forms a new com- 
 pound, by uniting with one of the constituents of the de- 
 composed body. 
 
 216. The observation, that a certain class of com- 
 pounds decompose themselves into new combinations, 
 merely by contact with one another, without the acting 
 body uniting with one of the new products, or without 
 losing one of its constituents, has caused Berzelius to 
 consider the above decomposition as dependent upon a 
 new force, which new force is only called into action by 
 the contact of the bodies, and the decomposition of the 
 compounds is the result. He names it the catalytic 
 force, and compares it with the peculiar activity of the 
 human organization, which possesses the property of 
 
 * For the explanation of chemical formulae, &c., see Webster's 
 Chemislnj, 3d edit. 
 
CATALYTISM. 45 
 
 preparing those substances from the food, which are 
 necessary to its existence, as blood, &ic. 
 
 Sugar and water in contact with yest are decomposed 
 into carbonic acid and alcohol : amygdalin, in contact 
 with emulsin, is decomposed into prussic acid and oil of 
 bitter almonds : deutoxide of hydrogen, in contact with 
 peroxide of manganese, is decomposed into oxygen gas 
 and water : boiling thick syrup of sugar becomes, by 
 the addition of ,00 po of oxalic acid, as fluid as water, 
 and loses its faculty of crystallization. 
 
 Although it cannot be denied, that these facts are in- 
 explicable, according to the ordinary decomposition of 
 a salt by means of an acid, yet it affords not the slight- 
 est ground for the creation of a force by means of a new 
 word, which likewise furnishes no explanation of the 
 phenomena. The adoption of this new force is preju- 
 dicial to the unfolding of the science, while the under- 
 standing is satisfied with this plausible explanation, and 
 thus places a limit to further research. 
 
 The smallest quantity of the acting body (yest) which 
 is sufficient to decompose a great mass of a chemical 
 compound, can afford no ground to seek its explanation 
 in a particular force (a small quantity of nitric acid gas 
 is sufficient to form a great mass of sulphuric acid), and 
 so long as it remains unknown what the yest loses in fer- 
 mentation, so long must the explanation of this decom- 
 position be left to future researches. 
 
46 INTRODUCTION. 
 
 CHAPTER VII. 
 
 THEORY OF THE CONSTITUTION OF SALTS. 
 
 217. Under the term Salt, in the most restricted 
 sense, is understood, a combination of two compound 
 bodies, which both possess as a constituent, a common 
 element, namely, a metalloid. 
 
 The most important classes of salts are the follow- 
 ing : — 
 
 218. Oxygen Salts. — They are formed by the com- 
 bination of a metallic oxide (of a base) with the oxide 
 of a metalloid (acid) ; or, by the higher degree of ox- 
 idation of a metal with another metallic oxide. That 
 oxide is called a basic metallic oxide, which, in all cases, 
 acts the part of a salifiable base. 
 
 219. The capacity of a base to neutralize an acid, is 
 independent of the quantity of its radical ; it is depen- 
 dent upon the proportion of oxygen which it contains. 
 (Consequences of 192, 193, and 202.) 
 
 220. When a certain quantity of an acid is neutral- 
 ized by different bases, the quantity of the oxygeu in all 
 these bases is the same, however different their weight 
 may be. (Consequences of 192-202.) 
 
 221. The proportion of oxygen of the acid stands in 
 a simple relation to the oxygen of the base, which forms 
 with it a neutral- salt. The proportion of oxygen of 
 both is either the same, or a multiple in whole numbers 
 of the oxygen of the base. 
 
 (Consequences of 202. The oxygen of the base must 
 
THEORY OF SALTS. 47 
 
 be related to the oxygen of the acid, as the number of 
 the atoms of the oxygen of the base is to the number of 
 the atoms of the oxygen of the acid.) 
 
 222. The saturating capacity of an acid is the con- 
 stant quantity of oxygen in different quantities, by 
 weight, of bases, which is necessary in order to form a 
 neutral salt with 100 parts of acid ; 100 parts of ni- 
 tric acid saturate a certain quantity of any base con- 
 taining 14.75 oxygen, consequently, the saturating ca- 
 pacity of nitric acid is 14.75, or -^th of its oxygen. 
 
 The saturating capacity of. sulphuric acid is 19.96. 
 Hence, the saturating capacity of sulphuric acid (19.96) 
 is said to be greater than that of nitric acid (14.75), and 
 we express thereby, that with the same quantity of 
 acids, a greater quantity of base is neutralized by the 
 one than by the other. (Consequences of unlike atom- 
 ic weights of the acids.) 
 
 223. The composition of a metallic oxide can be 
 found, from the composition of its neutral compounds 
 with one or two acids, when the saturating capacity of 
 the acid is known. 
 
 224. Those combinations of an acid with different 
 bases in which the saturating capacity of the acid is con- 
 stant, are denominated the neutral salts of this acid, 
 whatever may be the reactions of the salts. 
 
 225. Those salts are named basic^ which contain 
 twice, thrice, &c., the quantity of base of the neutral 
 salt. 
 
 In the basic salts of sulphuric acid, the oxygen of 
 the base is to that of the acid as 2 : 3, or 3 : 3, &c. 
 They consist of 2 or 3 atoms base, with 1 atom acid. 
 
 226. Double Salts are compounds of two or more 
 
48 INTRODUCTION. 
 
 salts of different bases, or acids. There exist neutral 
 and basic double salts. 
 
 227. Compounds of acids with water, in which the 
 quantity of the oxygen of the water is the same as the 
 oxygen of a metallic oxide which forms with these acids, 
 neutral salts, are called the hydrates of these acids. 
 (They are salts, in which, the basic metallic oxide is re- 
 placed by an atom of water.) 
 
 228. The basic water in the hydrated acids can only 
 be separated by means of a powerful base. 
 
 229. Acid Salts are combinations of the neutral salts 
 with the hydrate of the same acid. (Bisulphate of pot- 
 ash, for example, a double salt of two bases, in which 
 the water is one. Exception, — bi-chromate of pot- 
 ash.) 
 
 230. A class of salts, in which the hydrate water of 
 the acids enters into the composition of the salts, is 
 named Halhydrate.* 
 
 Neutral sulphate of soda contains 10 atoms water, 
 which can be perfectly separated by 100^ C. ; the hy- 
 drate water of the acid is perfectly replaced, and separ- 
 ated by its combination with soda ; the 10 atoms of water 
 which the salt contains is water of crystallization. Sul- 
 phate of zinc contains 7 atoms of water, of which 6 
 atoms can be separated by 100'^ C. ; the 7th atom is 
 more powerfully united. 
 
 231. Halhydrates do not unite with one another. 
 This class of salts forms no double salts with one an- 
 other. 
 
 * Being at a loss for a word to distinguish this class of salts, I have 
 adopted the expression of the original, which is derived from the 
 Greek word aks, salt. — L. 
 
HALHYDRATES. ,49 
 
 232. Halhydrates only form double salts with those 
 salts in which the acid has lost its hydrate water. (Sul- 
 phate of zinc, sulphate of lime are halhydrates, and do 
 not unite with one another. Sulphate of zinc, however, 
 as well as sulphate of lime form double salts with the 
 sulphates of potash and soda.) 
 
 233. In the double salts, the hydrate water of the hal- 
 hydrates is replaced by a corresponding quantity of an- 
 other salt. 
 
 The knowledge of the halhydrates, that is, of those 
 salts, which do not possess the property of forming 
 double salts with one another, is, in many decomposi- 
 tions, of the greatest importance. If it is wished to 
 change acetate of lime into acetate of soda by double 
 decomposition with sulphate of soda, according to cal- 
 culation for 1 eq. acetate of lime, it is only necessary to 
 have 1 eq. sulphate of soda ; but it is requisite to have 
 double the quantity of the latter, as the gypsum is a hal- 
 hydrate, with water of crystallization. By contact with 
 the sulphate of soda, the halhydrate water is replaced by 
 1 atom of sulphate of soda, and there is produced a 
 double salt, which is precipitated in the water. The 
 hardening of hydrated gypsum, when it is in the state of 
 powder, moistened with many saline solutions, arises 
 from the same cause. 
 
 234. When, in a neutral salt, the quantity of the met- 
 al is increased or diminished, the salt remains neutral, 
 (consequence of 220) for the saturating capacity of the 
 acid is not changed. 
 
 235. If in a neutral salt, the oxygen of the base is 
 increased, the saturating capacity of the acid, and there- 
 fore their quantities must be increased in the same rela- 
 tion, when the salt should remain neutral. In the oppo- 
 
 5 
 
50 INTRODUCTION. 
 
 site case, the salt will be either totally or partially con- 
 verted into a basic salt (consequences of 220 and 221). 
 
 236. Certain compounds of two metallic sulphurets, 
 in which the proportion of sulphur of one of the metallic 
 sulphurets corresponds to the proportion of oxygen of a 
 basic metallic oxide and the proportion of sulphur of the 
 other sulphuret corresponds to the proportion of oxygen, 
 of an oxygen acid of the same metal, are denominated 
 sulphur salts. 
 
 Chlorine salts are compounds of one, two, three, or 
 more metallic chlorides ; fluorine salts are compounds 
 of two, &c., metallic fluorides, &ic. 
 
 237. When an hydrogen acid is brought in contact 
 with metallic oxides, both are mutually decomposed ; 
 there results water from the hydrogen of the hydrogen 
 acid uniting with the oxygen of the metallic oxide, and 
 the radical of the hydrogen acid unites with the metal of 
 the metallic oxide. (Exception, — with alumina, &c.) 
 
 238. The basic metallic oxides are divided into cer- 
 tain groups, in reference to their solubility in water, and 
 their capacity perfectly to destroy the acid characters of 
 the acids. A knowledge of the same will be found of 
 great use. 
 
 a. Pure alkalies are the oxides of potassium, so- 
 dium, lithium ; they are very soluble in water, the solu- 
 tion attacks the skin, and they form soluble salts with 
 carbonic acid.* 
 
 b. Earthy alkalies are the oxides of barium, stron- 
 tium, calcium, magnesium ; they are difficultly soluble 
 in water, not so caustic, and form with carbonic acid, 
 insoluble salts. 
 
 * Ammonia, whicli is composed of hydrogen and nitrogen, is often 
 called the volatile alkali j it is a gas. 
 
ALKALINE EARTHS. 51 
 
 c. Earths, they are totally insoluble in water, have no 
 action upon vegetable colors, and do not unite with car- 
 bonic acid. To this group belongs alumina, &c. 
 
 The salts of the alkalies (a b) were formerly named 
 neutral salts, and those of the earths and other metallic 
 oxides intermediate. 
 
 239. The four simple bodies, viz. chlorine, bromine, 
 iodine, fluorine, before mentioned, are called haloid.* 
 
 240. The combinations of the haloids with metals are 
 named haloid salts.f 
 
 * From aX;, sea salt, and iTSes,form, for being analogous to sea- 
 salt. 
 
 t For a more particular description of the salts, see Webster's Chem- 
 istry, 3d edit. 104. 
 
\ 
 
ORGANIC CHEMISTRY 
 
 APPLIED TO 
 
 AGRICULTURE, 
 
 CHAPTER I. 
 
 OF THE CHEMICAL PROCESSES IN THE NUTRITION OF 
 VEGETABLES, AND THE CONSTITUENT ELEMENTS 
 OF PLANTS. 
 
 The object of organic chemistry * is to discover the 
 chemical conditions which are essential to the life and 
 perfect developement of animals and vegetables, and, 
 generally, to investigate all those processes of organic 
 nature which are due to the operation of chemical laws. 
 
 The continued existence of all living beings is depen- 
 dent on the reception by them of certain substances, 
 which are applied to the nutrition of their frame. An 
 inquiry, therefore, into the conditions on which the life 
 and growth of living beings depend, involves the study 
 
 * Every vegetable and animal constitutes a machine of greater or 
 less complexity, composed of a variety of parts dependent on each 
 other, and acting all of them to produce a certain end. Vegetables 
 and animals on this account are called organized beings, and the chem- 
 ical history of those compounds which are. of animal or vegetable 
 origin, or of organic substances, is called organic chemistry. See 
 Thomson's Chemistry of Organic Bodies, and Webster's Manual of 
 Chemistry, 3d edit., p. 362. 
 
 5* 
 
54 OF THE CONSTITUENT ELEMENTS 
 
 of those substances which serve them as nutriment, as 
 well as the investigation of the sources whence these 
 substances are derived, and the changes which ihey 
 undergo in process of assimilation. 
 
 The primary source whence man and animals derive 
 the means of their growth and support is the vegetable 
 kingdom. 
 
 Plants, on the other hand, find new nutritive material 
 only in inorganic substances. 
 
 The purport of this work is to elucidate the chemical 
 processes engaged in the nutrition of vegetables. 
 
 It will be devoted to the examination of the matters 
 which supply the nutriment of plants, and of the changes 
 which these matters undergo in the living organism. 
 The chemical compounds which afford to plants their 
 principal constituents, viz. carbon and nitrogen, will 
 come under consideration, as well as the relations in 
 which the vital functions of vegetables stand to those of 
 the animal economy and to other phenomena of nature. 
 
 Carbon* enters into the composition of all plants, 
 and of all their different parts or organs. 
 
 The substances which constitute the principal mass of 
 every vegetable are compounds of carbon with oxygen 
 and hydrogen in the proper relative proportions for form- 
 ing water. Woody fibre, starch, sugar, and gum, for 
 example, are such compounds of carbon with the ele- 
 ments of water. In another class of substances con- 
 taining carbon as an element, oxygen and hydrogen are 
 
 * Carbon is the pure inflammable principle which is the character- 
 istic ingredient of all kinds of charcoal. The diamond is pure car- 
 bon. Wood charcoal contains about l-50th of its weight of alkaline 
 and earthy salts, which constitute the ashes when it is burned. 
 
OF PLANTS. 55 
 
 again present ; but the proportion of oxygen is greater 
 than would be required for producing water by union 
 with the hydrogen. The numerous organic acids met 
 with in plants belong, with few exceptions, to this class. 
 
 A third class of vegetable compounds contain carbon 
 and hydrogen, but no oxygen, or less of that element 
 than would be required to convert all the hydrogen into 
 water. These may be regarded as compounds of carbon 
 with the elements of water and an excess of hydrogen. 
 Such are the volatile and fixed oils, wax, and the resins. 
 Many of them have acid characters. 
 
 The juices of all vegetables contain organic acids, 
 generally combined with the inorganic bases, or metallic 
 oxides ; for these metallic oxides exist in every plant, 
 and may be detected in its ashes after incineration. 
 
 JsTitrogen* is an element of vegetable albumen and 
 
 * This gas was discovered in 1772, and is called also azote or azotic 
 gas, from the Greek expressive of its being incapable of supporting 
 life. The name JVitrogen was given to it from its entering into the 
 composition of nitric acid (aqua fortis). It has been suspected to 
 be a compound, but this has not been verified. The atmosphere is 
 composed of four fifths nitrogen and one fifth oxygen, not, however 
 chemically united ; it also contains a ten thousandth part of carbonic 
 acid and watery vapor. A mixture of oxygen and nitrogen in the 
 proportions named, exhibits the general properties of the atmosphere. 
 Nitrogen may be obtained from common air by removing its oxygen, 
 and from the lean part of flesh meat by boiling it in diluted nitric 
 acid. It unites with different proportions of oxygen, and forms as 
 many distinct compounds, viz. 
 
 c ( Protoxide of Nitrogen, nitric 
 \ oxide, or exhilarating gas. 
 
 Binoxide of Nitrogen 
 
 or Nitric oxide. 
 Hyponitrous acid. 
 Nitrous acid. 
 Nitric acid. 
 For other details, see Webster's Chemistry, 3d edit., p. 134, «S:c. 
 
 Ixyg. 
 
 
 Mtroi_ 
 
 100 
 
 + 
 
 50 
 
 100 
 
 + 
 
 100 
 
 100 
 
 + 
 
 150 
 
 100 
 
 + 
 
 200 
 
 100 
 
 + 
 
 250 
 
56 OF THE CONSTITUENT ELEMENTS OF PLANTS. 
 
 gluten* ; it is a constituent of the acids, and of what 
 are termed the "indifferent substances" of plants, as 
 well as of those peculiar vegetable compounds which 
 possess all the properties of metallic oxides, and are 
 known as " organic bases." 
 
 Estimated by its proportional weight nitrogen forms 
 only a very small part of plants, but it is never entirely 
 absent from any part of them. Even when it does not 
 absolutely enter into the composition of a particular part 
 or organ, it is always to be found in the fluids which 
 pervade it. 
 
 It follows from the facts thus far detailed, that the de- 
 velopement of a plant requires the presence, first, of 
 substances containing carbon and nitrogen, and capable 
 of yielding these elements to the growing organism ; 
 secondly, of water and its elements ; and lastly, of a 
 soil to furnish the inorganic matters which are likewise 
 essential to vegetable life. 
 
 * Gluten is the tough elastic substance which remains after the 
 starch of wheat flour has been removed by washing with water. By 
 putrefaction it yields an offensive odor, and when distilled furnishes 
 ummonia, in this resembling some animal products. When fresh 
 gluten is digested in hot alcohol, the substance is obtained which has 
 been called vegetable albumen. Gluten is found in many seeds, es- 
 pecially in wheat associated with albumen and starch. It is the pres- 
 ence of this substance that renders wheaten flour so nutritious. The 
 wheat of the South of Europe, being rich in gluten, is employed in 
 the manufacture of macaroni, vermicelli, &c. 
 
COMPOSITION OF HUMUS. 57 
 
 CHAPTER II. 
 
 OF THE ASSIMILATION OF CARBON. 
 
 The fertility of every soil is generally supposed by 
 vegetable physiologists to depend on the presence in it 
 of a peculiar substance to which they have given the 
 name of humus. This substance, believed to be the 
 principal nutriment of plants, and to be extracted by 
 them from the soil in which they grow, is itself the pro- 
 duct of the decay of other plants. 
 
 Humus is described by chemists as a brown sub- 
 stance, easily soluble in alkalies, but only slightly solu- 
 ble in water, and produced during the decomposition of 
 vegetable matters by the action of acids or alkalies. It 
 has, however, received various names according to the 
 different external characters and chemical properties 
 which it presents. Thus, ulmin, humic acid, coal of 
 humus, and humin, are names applied to modifications of 
 humus. They are obtained by treating peat, woody 
 fibre, soot, or brown coal with alkalies ; by decom- 
 posing sugar, starch, or sugar-of-milk by means of 
 acids ; or by exposing alkaline solutions of tannic and 
 gallic acids to the action of the air. 
 
 The modifications of humus which are soluble in 
 alkalies, are called humic acid; while those which are 
 insoluble have received the designations of humin and 
 coal of humus.* 
 
 * The soluble matters were formerly called by the eminent Swedish 
 chemist Berzelius, extract of humus, and the insoluble geine (from 
 the Greek yj, the earth,) also apothcme and carbonaceous humus. 
 
58 OF THE ASSIMILATION OF CARBON. 
 
 The names given to these substances might cause it 
 to be supposed that their composition is identical. But 
 a more erroneous notion could not be entertained ; 
 
 This substance is now known to be composed of various ingredients, 
 and of these the two acids, which have received the names of Crenic 
 and ^pocrenic, are particularly interesting. 
 
 Tliese acids were discovered by Berzelius in the waters of certain 
 springs in Sweden. The crenic acid was named from the Greek 
 x^rivn, afounlain. It imparted to the water a yellowish color and dis- 
 agreeable taste. On exposure to the air, an ochrey sediment was 
 deposited which consisted chiefly of iron in the state of an oxide com- 
 bined with the crenic acid. 
 
 This acid when separated is yellow and transparent, free from 
 smell, with a sharp, astringent taste, soluble in water and alcohol. 
 It combines with bases and forms salts called crcnates. 
 
 By exposure to the ah apocrenic acid is formed, — ariyfrom, denot- 
 ing its origin. This acid was obtained from the ochre of the water, 
 and is brown, resembling vegetable extract. 
 
 These acids were supposed by Berzelius to occur frequently in 
 water, and this has since been verified, both in Europe and in this 
 country. 
 
 The various Reports on the agriculture and geology of the United 
 States contain abundant evidence that these acids exist in our soils, 
 and in peat, and that the crenic acid forms soluble salts with lime. 
 
 Ihe substances which have been called extract of humus and 
 geine, some chemists have considered identical with the extract 
 obtained from the bark of the elm, and the substance formed by fusing 
 sawdust with potash. Others view the principal part of those sub- 
 stances as a compound of the crenic and apocrenic acids with bases, 
 such as lime, magnesia, oxide of iron, &c. Apocrenic acid forms an 
 insoluble substance with lime; crenic acid forms soluble compounds 
 with alkalies, and these acids have been found in soils and peat in 
 Rhode Island, Maine, and New Hampshire. The crenate of lime 
 exists in the subsoil. (Dr. C. T. Jackson.) 
 
 Dr. Thomson is of opinion that there are various species of this 
 substance, differing from each other according to the plants from 
 which it has been derived. He slates the proportion of" apotheme " 
 in an analysis of wheat to have been about 20^ per cent. 
 
 Although by chemical analysis the substance which has been called 
 geine has been ascertained to be a compound, there will be conven- 
 
COMPOSITION OF HUMUS. 
 
 59 
 
 since even sugar, acetic acid, and colophan (rosin) do 
 not differ more widely in the proportions of their con- 
 
 ience perhaps in retaining the term to express the mass of uutritive 
 matters which soils and composts afford. Dr. S. L. Dana considers 
 geine as forming tiie basis of all the nourishing part of all vegetable 
 manures, and in the three states of " vegetable extract, geine, and 
 carbonaceous mould " to be the principle which gives fertility to soils 
 long after the action of common manures has ceased. See Report on 
 the reexamination of the Economical Geology of Massachusetts. In 
 the Third Report on the .Agriculture of the Slate of Massachusetts, 
 1840, Dr. Dana remarks, that geine " is the decomposed organic mat- 
 ter of the soil. It is the product of putrefaction ; continually sub- 
 jected to air and moisture, it is finally wholly dissipated in air, leaving 
 only the inorganic bases of the plant, with which it was once com- 
 bined. Now whether we consider this as a simple substance, or 
 composed of several others, called crenic, apocrenic, puteanic, ulmic 
 acids, glairin, apotheme, extract, humus, or mould, agriculture ever 
 has, and probably ever will consider it one and the same thing, re- 
 quiring always similar treatment to produce it; similar treatment to 
 render it soluble when produced ; similar treatment to render it an 
 effectual manure. It is the end of all compost heaps to produce solu- 
 ble geine, no matter how compound our chemistry may teach this 
 substance to be." page 191. 
 
 Dr. Dana has given the following as the average quantity of 
 " geine '" in the different geological varieties of the soils of Massachu- 
 setts : 
 
 Soluble Geine. 
 2.25 
 
 Insoluble Geine 
 
 2.15i^ 
 
 Soil. 
 Alluvium, 
 
 Tertiary Argillaceous, 3.94 
 
 Sandstone, 3.28 
 
 Graywacke, 3.60 
 
 Argillaceous Slate, 5.77 
 
 Limestone, 3 40 
 
 Mica Slate, 4.34 
 
 Talcose Slate, 3.67 
 
 Gneiss, 4.30 
 
 Granite, 4.05 
 
 Sienite, 4.40 
 
 Porphyry, 5 97 
 
 Greenstone, 4.56 
 See Professor Hitchcock's Report, and ^American Journal of Science^ 
 Vol. XXXVI, Art. XII. 
 
60 OF THE ASSIMILATION OF CARBON. 
 
 stiluent elements, than do the various nnodifications of 
 hwnus. 
 
 Humic acid formed by the action of hydrate * of 
 potash upon sawdust contains, according to the accurate 
 analysis of Peligot, 72 per cent, of carbon, while the 
 humic acid obtained from turf and brown coal contains, 
 according to Sprengel, only 58 per cent. ; that pro- 
 duced by the action of dilute sulphuric acid upon sugar, 
 57 per cent, according to Malaguti ; and that, lastly, 
 which is obtained from sugar or from starch, by means 
 of muriatic acid, according to the analysis of Stein, 64 
 per cent. All these analyses have been repeated with 
 care and accuracy, and the proportion of carbon in the 
 respective cases has been found to agree with the esti- 
 mates of the different chemists above mentioned ; so 
 that there is no reason to ascribe the difference in this 
 respect between the varieties of humus to the mere dif- 
 ference in the methods of analysis or degrees of expert- 
 ness of the operators. Malaguti states, moreover, that 
 humic acid contains an equal number of equivalents of 
 oxygen and hydrogen, that is to say, that these elements 
 exist in it in the proportions for forming water ; while, 
 ^''%^^^^rding to Sprengel, the oxygen is in excess, and 
 ^V^^igot even estimates the quantity of oxygen at 14 
 %vVSqiiivalents, and the hydrogen at only 6 equivalents, 
 ^■C*MW^""g tlie deficiency of hydrogen as great as 8 equiva- 
 
 ^J'JrTtLis quite evident, therefore, that chemists have been 
 •^ISwhe habit of designating all products of the decompo- 
 
 4tt%^ 
 
 ^^j^j^HyHmips are compounds of oxides, sails, «&c. with definite quan- 
 
 ^*^3h'^ °^ water, — a substance from wliich all the water has been 
 . , T,^^©iMoved is anhydrous. Even after exposure to a red heat caustic 
 potash retains water. 
 
PROPERTIES OF HUMUS. 61 
 
 sition of organic bodies which had a brown or brownish 
 blacl< color by the names of hnmic acid or hnmin, ac- 
 cording as they were soluble or insoluble in alkalies ; 
 although in their composition and mode of origin, the 
 substances thus confounded might be in no way allied. 
 
 Not the slightest ground exists for the belief that one 
 or other of these artificial products of the decomposi- 
 tion of vegetable matters exists in nature in the form 
 and endowed with the properties of the vegetable con- 
 stituents of mould ; there is not the shadow of a proof 
 that one of them exerts any influence on the growth of 
 plants either in the way of nourishment or otherwise. 
 
 Vegetable physiologists have, without any apparent 
 reason, imputed the known properties of the humus 
 and humic acids of chemists to that constituent of mould 
 which has received the same name, and in this way 
 have been led to their theoretical notions respecting the 
 functions of the latter substance in vegetation. 
 
 The opinion that the substance called humus is ex- 
 tracted from the soil by the roots of plants, and that 
 the carbon entering into its composition serves in some 
 form or other to nourish their tissues, is so general and 
 so firmly established, that hitherto any new argument 
 in its favor has been considered unnecessary ; the obvi- 
 ous difference in the growth of plants according to the 
 known abundance or scarcity of Jnimus in the soil, 
 seemed to afford incontestable proof of its correctness. 
 
 Yet, this position, when subn)itted to a strict examina- 
 tion, is found to be untenable, and it becomes evident 
 from most conclusive proofs that humus in the form in 
 which it exists in the soil does not yield the smallest 
 nourishment to plants. 
 
 The adherence to the above incorrect opinion has 
 - • • » ^ 
 
 . > _r 
 
 -: V 
 
62 OF THE ASSIMILATION OF CARBON. 
 
 hitherto rendered it impossible for the true theory of 
 the nutritive process in vegetables to become known, 
 and has thus deprived us of our best guide to a rational 
 practice in agriculture. Any great improvement in that 
 most important of all arts is inconceivable without a 
 deeper and more perfect acquaintance with the sub- 
 stances which nourish plants, and with the sources 
 whence they are derived ; and no other cause can be 
 discovered to account for the fluctuating and uncertain 
 state of our knowledge on this subject up to the present 
 time, than that modern physiology has not kept pace 
 with the rapid progress of chemistry. 
 
 In the following inquiry we shall suppose the hwmis 
 of vegetable physiologists to be really endowed with 
 ihe properties recognised by chemists in the brownish 
 black deposites which they obtain by precipitating an 
 alkaline decoction of mould or peat by means of acids, 
 and which they name hvmic acid.* 
 
 * The extract obtained by Berzelius from black, brownish soils has 
 been designated as humic extract, in some cases with a substance 
 called glairin. The glairin is described by Thomson as a pe- 
 culiar substance wliich has been observed in certain sulphureous 
 ♦ mineral waters, and was first noticed by Vauquelin (jinn, de Chim. 
 XXXIX. 173), who described several of its properties and considered 
 it analogous to gelatin. An account of it was drawn tip by M, An- 
 glada, of Montpellier, and communicated to the Royal Academy of 
 Medicine of Paris, in 1827. It gelatinizes with water when suffi- 
 ciently concentrated. Sometimes it is white, and at others of a red 
 color ; when dried it shrinks to g^th of its bulk when moist. It satu- 
 rates ammonia, and decomposes several metallic salts. It is destitute 
 of smell and taste. It does not glue substances together like gelatin 
 and albumen, it yields ammonia by decomposition, and is capable 
 of putrefaction like animal bodies. The general opinion is, that it is 
 of vegetable origin, and allied to the genus f/-cr/ic//a, though its ex- 
 istence in mineral waters has not been accounted for. Thomson's 
 Oriranic Ckemislru, (I'M. I found it very abundant about the iiot 
 sulphureous waters of the island of St. Michael, Azores._^ */f 4^f»4it. 
 
ABSORPTION OF HUMUS. 63 
 
 Humic acid, when first precipitated, is a flocculent 
 substance, is soluble in 2500 times its weight of water, 
 and combines with alkalies, lime and magnesia, forming 
 compounds of the same degree of solubility. (Spren- 
 
 gel.) 
 
 Vegetable physiologists agree in the supposition 
 that by the aid of water humus is rendered capable of 
 being absorbed by the roots of plants. But according 
 to the observation of chemists, humic acid is soluble 
 only when newly precipitated, and becomes completely 
 insoluble when dried in the air, or when exposed in the 
 moist state to the freezing temperature. (Sprengel.) 
 
 Both the cold of winter and the heat of summer 
 therefore are destructive of the solubility of humic acid, 
 and at the same time of its capability of being assimi- 
 lated by plants. So that, if it is absorbed by plants, 
 it must be in some altered form.* 
 
 The correctness of these observations is easily de- 
 monstrated by treating a portion of good mould with 
 cold water. The fluid remains colorless, and is found 
 to have dissolved less than 100,000 part of its weight 
 of organic matters, and to contain merely the salts which 
 are present in rain-water. 
 
 Decayed oak-wood, likewise, of which humic acid is 
 the principal constituent, was found by Berzelius to 
 yield to cold water only slight traces of soluble mate- 
 rials ; and I have myself verified this observation on 
 the decayed wood of beech and fir. 
 
 These facts, which show that humic acid in its un- 
 
 * According to Dr. Jackson, the substances contained in humic 
 extract form soluble salts with lime. The acids form soluble salts 
 with the same substance, and the salts are decomposed in the process 
 of vegetation. 
 
64 OF THE ASSIMILATION OF CARBON. 
 
 altered condition cannot serve for the nourishment of 
 plants, have not escaped the notice of physiologists ; 
 and hence they have assumed that the lime or the 
 different alkalies found in the ashes of vegetables render 
 soluble the humic acid and fit it for the process of 
 assimilation. 
 
 Alkalies and alkaline earihs do exist in the different 
 kinds of soil in sufficient quantity to form such soluble 
 compounds with the humic acid. 
 
 Now, let us suppose that humic acid is absorbed by 
 plants in the form of that salt which contains the largest 
 proportion of humic acid, namely, in the form of humate 
 of lime, and then from the known quantity of the alka- 
 line bases contained in the ashes of plants, let us calcu- 
 late the amount of humic acid which might be assimilated 
 in this manner. Let us admit, likewise, that potash, 
 soda, and the oxides of iron and manganese have the 
 same capacity of saturation as lime with respect to hu- 
 mic acid, and then we may take as the basis of our 
 calculation the analysis of M. Berthier, who found that 
 1000 lbs. of dry fir-wood yielded 4 lbs. of ashes, and 
 that in every 100 lbs. of these ashes, after the chloride 
 of potassium and sulphate of potash were extracted, 
 53 lbs. consisted of the basic metallic oxides, potash, 
 soda, lime, magnesia, iron, and manganese. 
 
 40,000 square feet* Hessian measure of wood-land 
 yield annually, according to Dr. Heyer, on an average, 
 2650 lbs. Hessian of dry fir-wood, which contain 5*6 lbs. 
 Hessian of metallic oxides. 
 
 * [The numbers in the text in Hessian feet and pounds will show 
 a proportion to other numbers equally well as if they were reduced 
 to their equivalents in Knijlisli. For those, however, who prefer 
 knowing the exact English quantities, a table of equivalents is given 
 at the end. — P.] 
 
ABSORPTION OF HUMUS. 65 
 
 Now, according to the estimates of Malaguti and 
 Sprengel, 1 lb. Hessian of lime combines chemically 
 with 10-9 lbs. Hessian of humic acid ; 5-6 lbs. of the 
 metallic oxides would accordingly introduce into the 
 trees 61 lbs. Hessian of humic acid, which, admitting 
 humic acid to contain 58 per cent, of carbon, would 
 correspond to 91 lbs. Hessian of dry wood. But 
 we have seen that 2650 lbs. of fir-wood are really 
 produced. 
 
 Again, if the quantity of humic acid which might be 
 introduced into wheat in the form of humates is calculat- 
 ed from the known proportion of metallic oxides exist- 
 ing in wheat straw, (the sulphates and chlorides also 
 contained in the ashes of the straw not being included,) 
 it will be found that the wheat growing on 40,000 square 
 feet of land would receive in that way 571 lbs. Hessian 
 of humic acid, corresponding to 85 lbs. Hessian of 
 woody fibre. But the extent of land just mentioned 
 produces, independently of the roots and grain, 1780 
 lbs. Hessian of straw, the composition of which is the 
 same as that of woody fibre. 
 
 It has been taken for granted in these calculations 
 that the basic metallic oxides which have served to 
 introduce humic acid into the plants do not return to 
 the soil, since it is certain that they remain fixed in the 
 parts newly formed during the process of growth. 
 
 Let us now calculate the quantity of humic acid 
 which plants can receive under the most favorable cir- 
 cumstances, viz through the agency of rain-water. 
 
 The quantity of rain which falls at Erfurt, one of the 
 
 most fertile districts of Germany, during the months of 
 
 April, May, June, and July, is stated by Schubler to 
 
 be 17| lbs. Hessian over every square foot of surface ; 
 
 6* 
 
66 OF THE ASSIMILATION OF CARBON. 
 
 40,000 square feet consequently receive 700,000 lbs. 
 Hessian of rain-water. 
 
 If, now, we suppose that the whole quantity of this 
 rain is taken up by the roots of a summer plant which 
 ripens four months after it is planted, so that not a 
 pound of this water evaporates except from the leaves 
 of the plant ; and if we further assume that the water 
 thus absorbed is saturated with humale of lime (the 
 most soluble of the bumates, and that which contains 
 the largest proportion of humic acid) ; then the plants 
 thus nourished would not receive more than 300 lbs. 
 Hessian of humic acid, since one part of humate of 
 lime requires 2500 parts of water for solution. 
 
 But the extent of land which we have mentioned 
 produces 2580 lbs. Hessian of corn (in grain and straw, 
 the roots not included,) or 20,000 lbs. Hessian of beet- 
 root (without the leaves and small radicle fibres). It is 
 quite evident that the 300 lbs. of humic acid, supposed 
 to be absorbed, cannot account for the quantity of car- 
 bon contained in the roots and leaves alone, even if the 
 supposition were correct, that the whole of the rain- 
 water was absorbed by the plants. But since it is 
 known that only a small portion of the rain-water which 
 falls upon the surface of the earih evaporates through 
 plants, the quantity of carbon which can be conveyed 
 into them in any conceivable manner by means of humic 
 acid must be extremely trifling in comparison with that 
 actually produced in vegetation. 
 
 Other considerations, of a higher nature, confute the 
 common view respecting the nutritive office of humic 
 acid, in a manner so clear and conclusive that it is 
 difficult to conceive how it could have been so generally 
 adopted. 
 
CARBON IN WOOD, &C. 6.7 
 
 Fertile land produces carbon in the fornri of wood, 
 hay, grain, and other kinds of growth, the masses of 
 which differ in a rennarkable degree. 
 
 2650 lbs. Hessian of firs, pines, beeches, &c. grow 
 as wood upon 40,000 square feet of forest-land, with 
 an average soil. The same superficies yields 2500 lbs. 
 Hessian of hay. 
 
 •A similar surface of corn-land gives from 18,000 to 
 20,000 lbs. Hessian of beet-root, or 800 lbs. Hessian 
 of rye, and 1780 lbs. Hessian of straw, 160 sheaves 
 of 14 lbs. Hessian each, in all, 2580 lbs. Hessian. 
 
 One hundred parts of dry fir-wood contain 38 parts 
 of carbon ; therefore, 2650 lbs. contain 1007 lbs. Hes- 
 sian of carbon. 
 
 One hundred parts of hay,* dried in air, contain 
 44*31 parts carbon. Accordingly, 2500 lbs. of hay 
 contain 1008 lbs. Hessian of carbon. 
 
 Beet-roots contain from 89 to 89-5 parts water, and 
 from 10*5 to 11 parts solid matter, which consists of 
 from 8 to 9 per cent, sugar, and from 2 to 2| per cent, 
 cellular tissue. Sugar contains 42*4 per cent. ; cellular 
 tissue, 47 per cent, of carbon. 
 
 20,000 lbs. of beet-root, therefore, if they contained 
 9 per cent, of sugar, and 2 per cent, of cellular tissue, 
 would yield 936 lbs. Hessian of carbon, of which 756 
 lbs. Hessian would be due to the sugar, and 180 lbs. 
 Hessian to the cellular tissue ; the carbon of the leaves 
 and small roots not being included in the calculation. 
 
 » 100 parts of hay, dried at 100° C. (212" F.) and burned with oxide 
 of copper in a stream of oxygen gas, yielded 51-93 water, 165-8 car- 
 bonic acid, and 0-82 of ashes. This gives 45-87 carbon, 5-76 hydrogen, 
 31-55 ogygen, and 6-82 ashes. Hay, dried in the air, loses 11-2 p. c. 
 water at 100° C. (212° F.) — Dr. Win. 
 
§8 OF THE ASSIMILATION OF CARBON. 
 
 One hundred parts of straw,* dried in air, contain 
 38 per cent, of carbon ; therefore 1780 lbs. of straw 
 contain G76 lbs. Hessian of carbon. One hundred 
 parts of corn contain 43 parts of carbon ; 800 lbs. must 
 therefore contain 344 lbs. Hessian; — in all, 1020 lbs. 
 Hessian of carbon. 
 
 40,000 square feet of wood and meadow land pro- 
 duce, consequently, 1007 lbs. of carbon ; while the 
 same extent of arable land yields in beet-root, without 
 leaves, 936 lbs. ; or in corn, 1020 lbs. 
 
 It must be concluded from these incontestable facts, 
 that equal surfaces of cultivated land of an average 
 fertility produce equal quantities of carbon : yet, how 
 unlike have been the different conditions of the growth 
 of the plants from which this has been deduced ! 
 
 Let us now inquire whence the grass in a meadow, 
 or the wood in a forest receives its carbon, since there 
 no manure, — no carbon, — has been given to it as 
 nourishment ? and how it happens, that the soil, thus 
 exhausted, instead of becoming poorer, becomes every 
 year richer in this element ? 
 
 A certain quantity of carbon is taken every year from 
 the forest or meadow, in the form of wood or hay, and, 
 in spite of this, the quantity of carbon in the soil aug- 
 ments ; it becomes richer in humus. 
 
 It is said, that in fields and orchards all the carbon 
 which may have been taken away as herbs, as straw, as 
 seeds, or as fruit, is replaced by means of manure ; and 
 yet this soil produces no more carbon than that of the 
 
 * Straw analyzed in the same manner, and dried at ICO" C, gave 
 46-37 p. c. of carbon, 5()8 p. c. of hydrogen, 4;l-93 p. c. of oxygen, 
 and 4 02 p. c. of ashes. Straw, dried in the air, at 100" C. lost 18 p. c. 
 of water. — Dr. Will. 
 
ORIGIN OF CARBON. 69 
 
 forest or meadow where it is never replaced. It cannot 
 be conceived that the laws for the nutrition of plants are 
 changed by culture, — that the sources of carbon for 
 fruit or grain, and for grass or trees, are different. 
 
 It is not denied that manure exercises an influence 
 upon the developement of plants ; but it may be affirm- 
 ed with positive certainly, that it neither serves for the 
 production of the carbon, nor has any influence upon it, 
 because we find ti)at the quantity of carbon produced by 
 manured lands is not greater than that yielded by lands 
 which are not manured. The discussion as to the man- 
 ner in which manure acts has nothing to do with the 
 present question, which is the origin of the carbon. 
 The carbon must be derived from other sources ; and 
 as the soil does not yield it, it can only be extracted 
 from the atmosphere. 
 
 In attempting to explain the origin of carbon in plants, 
 it has never been considered that the question is inti- 
 mately connected with that of the origin of humus. It 
 is universally admitted that humus arises from the decay 
 of plants. No primitive humus, therefore, can have 
 existed ; for plants must have preceded the humus. 
 
 Now, whence did the first vegetables derive their car- 
 bon ? and in what form is the carbon contained in the 
 atmosphere ? 
 
 These two questions involve the consideration of two 
 most remarkable natural phenomena, which by their re- 
 ciprocal and uninterrupted influence, maintain the life of 
 the individual animals and vegetables, and the continued 
 existence of both kingdoms of organic nature. 
 
 One of these questions is connected with the invaria- 
 ble condition of the air with respect to oxygen. One 
 hundred volumes of air have been found, at every peri- 
 
70 OF THE ASSIMILATION OP CARBON. 
 
 od and in every climate, to contain twenty-one volumes 
 of oxygen, with such small deviations, that they must be 
 ascribed to errors of observation. 
 
 Although the absolute quantity of oxygen contained 
 in the atmosphere appears very great when represented 
 by numbers, yet it is not inexhaustible. One man con- 
 sumes by respiration 45* Hessian cubic feet of oxygen 
 in 24 hours ; 10 centners of charcoal consume 58,112 
 cubic feet of oxygen during its combustion ; and a small 
 town like Giessen (with about 7000 inhabitants) extracts 
 yearly from the air, by the wood employed as fuel, 
 more than 1000 millions of cubic feet of this gas. 
 
 When we consider facts such as these, our former 
 statement, that the quantity of oxygen in the atmosphere 
 does not diminish in the course of agesf , — • that the air 
 at the present day, for example, does not contain less 
 oxygen than that found in jars buried for 1800 years in 
 Pompeii, — appears quite incomprehensible, unless some 
 source exists whence the oxygen abstracted is replaced. 
 How does it happen, then, that the proportion of oxy- 
 gen in the atmosphere is thus invariable ? 
 
 The answer to this question depends upon another ; 
 
 * [For the proportions in English weights and measures see the ta- 
 ble at the end of the volume.] 
 
 t The air contains, in maximo, lOififoo carbonic acid gas and loosoo 
 oxygeji gas. A man consumes, in one year, 1GC,075 cubic feet of 
 gas (or 45,000 cubic inches in one day, according to Lavoisier, Seguin. 
 and Davy) ; a tliousand million men must accordingly consume ICG 
 billion cubic feet in one year; this is equal to looo of ^'^^ quantity 
 which is contained in the air in the form of carbonic acid. Tlie car- 
 bonic acid in the air would thus be doubled in 1000 years, and man 
 alone would exhaust all the oxygen, and convert it into carbonic acid 
 in 303 times as many years. The consumption by animals, and by 
 the process of combustion, is not introduced into the calculation. 
 
ITS PROPORTION IN THE ATMOSPHERE. 71 
 
 namely, what becomes of the carbonic acid, which is 
 produced during the respiration of animals, and by the 
 process of combustion ? A cubic foot of oxygen gas, by 
 uniting with carbon so as to form carbonic acid, does 
 not change its volume. The billions of cubic feet of 
 oxygen extracted from the atmosphere, produce the 
 same number of billions of cubic feet of carbonic acid, 
 which immediately supply its place. 
 
 The most exact and most recent experiments of De 
 Saussiire, made in every season, for a space of three 
 years, have shown, that the air contains on an average 
 0.000415 of its own volume of carbonic acid gas ; so 
 that, allowing for the inaccuracies of the experiments, 
 which must diminish the quantity obtained, the propor- 
 tion of carbonic acid in the atmosphere may be regarded 
 as nearly equal to 1-1000 part of its weight. The quan- 
 tity varies according to the seasons ; but the yearly av- 
 erage remains continually the same. 
 
 We have no reason to believe that this proportion 
 was less in past ages ; and nevertheless, the in)mense 
 masses of carbonic acid, which annually flow into the 
 atmosphere from so many causes, ought perceptibly to 
 increase its quantity from year to year. But we find, 
 that all earlier observers describe its volume as from 
 one half to ten times greater than that which it has at the 
 present time ; so that we can hence at most conclude, 
 that it has diminished. 
 
 It is quite evident, that the quantities of carbonic acid 
 and oxygen in the atmosphere, which remain unchanged 
 by lapse of time, must stand in some fixed relation to 
 one another ; a cause must exist which prevents the 
 increase of carbonic acid, by removing that which is 
 constantly forming ; and there must be some means of 
 
72 OF THE ASSIMILATION OF CARBON. 
 
 replacing the oxygen, which is removed from the air by 
 the processes of combustion and putrefaction, as well as 
 by the respiration of animals. 
 
 Both these causes are united in the process of vege- 
 table life. 
 
 The facts which we have stated in the preceding 
 pages prove, that the carbon of plants must be derived 
 exclusively from the atmosphere. Now, carbon exists 
 in the atmosphere only in the form of carbonic acid ; 
 and, therefore, in a state of combination with oxygen. 
 
 It has been already mentioned likewise, that carbon 
 and the elements of water form the principal constitu- 
 ents of vegetables ; the quantity of the substances which 
 do not possess this composition being in very small pro- 
 portion. Now, the relative quantity of oxygen in the 
 whole mass is less than in carbonic acid. It is therefore 
 certain, that plants must possess the power of decom- 
 posing carbonic acid, since they appropriate its carbon 
 for their own use. The formation of their principal 
 component substances must necessarily be attended with 
 the separation of the carbon of the carbonic acid from 
 the oxygen, which must be returned to the atmosphere, 
 whilst the carbon enters into combination with water or 
 its elements. The atmosphere must thus receive a vol- 
 ume of oxygen for every volume of carbonic acid which 
 has been decomposed. 
 
 This remarkable property of plants has been demon- 
 strated in the most certain manner, and it is in the power 
 of every person to convince himself of its existence. 
 The leaves and other green parts of a plant absorb car- 
 bonic acid, and emit an equal vx)lume of oxygen. They 
 possess this property quite independently of the plant ; 
 for if, after being separated from the stem, they are 
 
ITS SOURCE, THE ATMOSPHERE. 73 
 
 placed in water containing carbonic acid, and exposed 
 in that condition to the sun's hght, the carbonic acid is, 
 after a time, found to have disappeared entirely from the 
 water. If the experiment is conducted under a glass 
 receiver filled with water, the oxygen emitted from the 
 plant may be collected and examined. When no more 
 oxygen gas is evolved, it is a sign that all the dissolved 
 carbonic acid is decomposed ; but the operation recom- 
 mences if a new portion of it is added. 
 
 Plants do not emit gas when placed in water which 
 either is free from carbonic acid, or contains an alkali 
 that protects it from assimilation. 
 
 These observations were first made by Priestley and 
 Sennebier. The excellent experiments of De Saussure 
 have further shown, that plants Increase in weight during 
 the decomposition of carbonic acid and separation of 
 oxygen. This increase in weight is greater than can be 
 accounted for by the quantity of carbon assimilated ; a 
 fact which confirms the view, that the elements of water 
 are assimilated at the same time. 
 
 The life of plants is closely connected with that of 
 animals, in a most simple manner, and for a wise and 
 sublime purpose. 
 
 The presence of a rich and luxuriant vegetation may 
 be conceived without the concurrence of animal life, 
 but the existence of animals is undoubtedly dependent 
 upon the life and development of plants. 
 
 Plants not only afford the means of nutrition for the 
 growth and continuance of animal organization, but they 
 likewise furnish that which is essential for the support of 
 the important vital process of respiration ; for besides 
 separating all noxious matters from the atmosphere, they 
 are an inexhaustible source of pure oxygen, which sup- 
 
74 OF THE ASSIMILATION OF CARBON. 
 
 plies the loss which the air is constantly sustaining. An- 
 imals, on the other hand, expire carbon, which plants 
 inspire ; and thus the composition of the medium in 
 which both exist, namely, the atmosphere, is maintained 
 constantly unchanged. 
 
 It may be asked. Is the quantity of carbonic acid in 
 the atmosphere, which scarcely amounts to 1-1 0th per 
 cent., sufficient for the wants of the whole vegetation on 
 the surface of the earth, — is it possible that the carbon 
 of plants has its origin from the air alone ? This ques- 
 tion is very easily answered. It is known that a column 
 of air, of 2216-66 lbs. weight, Hessian measure, rests 
 upon every square Hessian foot of the surface of the 
 earth ; the diameter of the earth and its superficies are 
 likewise known, so that the weight of the atmosphere 
 can be calculated with the greatest exactness. The 
 thousandth part of this is carbonic acid, which contains 
 upwards of 27 per cent, carbon. By this calculation it 
 can be shown, that the atmosphere contains 3000 billion 
 Hessian lbs. of carbon ; a quantity which amounts to 
 more than the weight of all the plants, and of all the 
 strata of mineral and brown coal, which exist upon the 
 earth. This carbon is, therefore, more than adequate 
 to all the purposes for which it is required. The quan- 
 tity of carbon contained in sea-water, is proportionally 
 still greater. 
 
 If, for the sake of argument, we suppose the su- 
 perficies of the leaves and other green parts of plants, 
 by which the absorption of carbonic acid is effected, 
 to be double that of the soil upon which they grow, 
 a supposition which is much under the truth in the 
 case of woods, meadows, and corn fields ; and if we 
 further suppose that carbonic acid equal to 0*00067 of 
 
ITS SOURCE, THE ATMOSPHERE. 75 
 
 the volume of the air, or 1-1 000th of its weight is ab- 
 stracted from it during every second of time, for eight 
 hours daily, by a field of 80,000 Hessian square feet ; 
 then those leaves would receive 1000 Hessian lbs. of 
 carbon in 200 days.* 
 
 But it is inconceivable, that the functions of the or- 
 gans of a plant can cease for any one moment during its 
 life. The roots and other parts of it, which possess 
 the same power, absorb constantly water and carbonic 
 acid. This power is independent of solar light. Dur- 
 ing the day, when the plants are in the shade, and dur- 
 ing the night, carbonic acid is accumulated in all parts 
 of their structure ; and the assimilation of the carbon 
 and the exhalation of oxygen commence from the in- 
 stant that the rays of the sun strike them. As soon as 
 a young plant breaks through the surface of the ground, 
 
 * The quantity of carbonic acid which can be extracted from the 
 air in a given lime, is shown by the following calculation. During the 
 whitewashing of a small chamber, the superficies of the walls and roof 
 of which we will suppose to be 105 square metres, and which receives 
 six coats of lime in four days, carbonic acid is abstracted from the air, 
 and the lime is consequently converted, on the surface, into a carbon- 
 ate. It has been accurately determined that one square decimetre re- 
 ceives in this way, a coating of carbonate of lime which weighs 0'732 
 grammes. Upon the 105 square metres, already mentioned, there 
 must accordingly be formed 7686 grains of carbonate of lime, which 
 contain 4325-6 grains of carbonic acid. The weight of one cubic de- 
 cimetre of carbonic acid being calculated at two grammes, (more ac- 
 curately 1-97978,) the above mentioned surface must absorb in four 
 days 2 163 cubic metres of carbonic acid. 2500 square metres (one 
 Hessian acre) would absorb, under a similar treatment, 51.^ cubic 
 metres = 3296 cubic feet of carbonic acid in four days. In 200 days 
 it would absorb 2375 cubic metres = 164,800 cubic feet, which con- 
 tain 10,300 lbs. Hessian of carbonic acid of which 2997 lbs. are car- 
 bon, a quantity three times as great as that which is assimilated by 
 the leaves and roots growing upon the same space. — L. 
 
76 OF THE ASSIMILATION OF CARBON. 
 
 it begins to acquire color from the top downwards ; and 
 the true formation of woody tissue commences at the 
 same time.* 
 
 The proper, constant, and inexhaustible sources of 
 oxygen gas are the tropics and warm climates, where a 
 sky, seldom clouded, permits the glowing rays of the 
 sun to shine upon an immeasurably luxuriant vegetation. 
 The temperate and cold zones, where artificial warmth 
 must replace deficient heat of the sun, produce, on the 
 contrary, carbonic acid in superabundance, which is 
 expended in the nutrition of the tropical plants. The 
 same stream of air, which moves by the revolution of 
 the earth from the equator to the poles, brings to us, in 
 its passage from the equator, the oxygen generated 
 there, and carries away the carbonic acid formed duiing 
 our winter f . 
 
 The experiments of De Saussure have proved, that 
 the upper strata of the air contain more carbonic acid 
 than the lower, which are in contact with plants ; and 
 
 * Plants that grow in tlie dark are well known to be colorless. 
 This is seen in the blanching of celery (etiolation), the earth is heap- 
 ed around the stalks to exclude the light. 
 
 t The objection has been urged that towards the end of autumn 
 and through the winter and early spring the air in our climate must 
 become impure, from the absence of leaves, — that the oxygen 
 must diminish and carbonic acid increase in the atmosphere. But 
 the different parts of the atmosphere are constantly mixed together by 
 the winds, which, when strong, move at the rate of from GO to 100 
 miles an hour. There are, too, the vast forests and savannas in 
 tropical climates always luxuriant in vegetation, and the air from 
 them passing often over the ocean or other large surfaces of water, 
 arrives in an uncontaminated state. The storms and tempests which 
 occur have also a salutary influence. By constant agitation and mo- 
 tion the equilibrium of the constituent parts of the atmosphere is thus 
 preserved. 
 
ITS SOURCE, THE ATMOSPHERE. 77 
 
 that the quantity is greater by night than by day, when 
 it undergoes decomposition. 
 
 Plants thus improve the air, by the removal of car- 
 bonic acid, and by the renewal of oxygen, which is 
 immediately applied to the use of man and animals. 
 The horizontal currents of the atmosphere bring with 
 them as much as they carry away, and the interchange 
 of air between the upper and lower strata, which their 
 difference of temperature causes, is extremely trifling 
 when compared with the horizontal movements of the 
 winds. Vegetable culture heightens the healthy state 
 of a country, and a previously healthy country would 
 be rendered quite uninhabitable by the cessation of all 
 cultivation. 
 
 The most important function in the life of plants, or 
 in other words, in their assimilation of carbon, is the 
 separation, we might almost say the generation, of ox- 
 ygen. No matter can be considered as nutritious, or 
 as necessary to the growth of plants, which possesses a 
 composition either similar to or identical with theirs, 
 and the assimilation of which, therefore, could take 
 place without exercising this function. 
 
 We have satisfactory proofs that decayed woody 
 fibre (humus) contains carbon and the elements of wa- 
 ter, without an excess of oxygen ; its composition 
 differing from that of woody fibre, in its being richer in 
 carbon. 
 
 Vegetable physiologists consider the formation of 
 woody fibre from humus as very simple ; they say, 
 humus has only to enter into chemical combination with 
 water, in order to efi'ect the formation of woody fibre, 
 starch, or sugar.* 
 
 * Meyen, Pflanzenphysiologie, ii. s. 141. 
 7 * 
 
78 OF THE ASSIMILATION OF CARBON. 
 
 But the same philosophers have informed us, that 
 aqueous solutions of sugar, starch, and gum, are im- 
 bibed by the roots of plants, and carried to all parts of 
 their structure, but are not assimilated ; they cannot, 
 therefore, be employed in their nutrition. We could 
 scarcely conceive a form more convenient for assimila- 
 tion than that of gum, starch, and sugar, for they all 
 contain the elements of woody fibre, and nearly in the 
 same proportiojis. 
 
 All the erroneous opinions concerning the modus 
 operandi of humus have their origin in the false notions 
 entertained respecting the most important vital functions 
 of plants ; analogy, that fertile source of error, having 
 unfortunately led to the very unapt comparison of the 
 vital functions of plants with those of animals. 
 
 Substances such as sugar, starch, &c., which contain 
 carbon and the elements of water, are products of the 
 life of plants, which live only whilst they generate them. 
 The same may be said of humus, for it can be formed 
 in plants, like the former substances. Smithsun, Jame- 
 son^ and Thomson, found that the black excretions of 
 unhealthy elms, oaks, and horse-chesnuts, consisted of 
 humic acid in combination with alkalies. Berzclius 
 detected similar products in the bark of most trees. 
 Now, can it be supposed, that the diseased organs of a 
 plant possess the power of generating the matter, to 
 which its sustenance and vigor are ascribed ? 
 
 How does it happen, it may be asked, that the ab- 
 sorption of carbon from the atmosphere by plants is 
 doubted by all botanists and vegetable physiologists, 
 and that by the greater number the purification of the 
 air by means of them is wholly denied '' 
 
 These doubts have arisen from the action of plants on 
 the air in the absence of light, that is, during the night. 
 
INFLUENCE OF THE SHADE ON PLANTS. 79 
 
 The experiments of Ingenhouss were in a great meas- 
 ure the cause of this uncertainty of oj3inion, regarding 
 the influence of plants in purifying the air. His obser- 
 vation, that green plants emit carbonic acid in the dark, 
 led De Saiissure and Grischow to new investigations, 
 by which they ascertained that under such conditions 
 plants do really absorb oxygen, and emit carbonic acid ; 
 but that the whole volume of air undergoes diminution 
 at the same time. From the latter fact it follows, that 
 the quantity of oxygen gas absorbed is greater, than the 
 volume of carbonic acid separated ; for if this were not 
 the case, no diminution could occur. These facts 
 cannot be doubted, but the views based on them have 
 been so false, that nothing, except the total want of ob- 
 servation, and the utmost ignorance of the chemical 
 relations of plants to the atmosphere, can account for 
 their adoption. 
 
 It is known, that nitrogen, hydrogen, and a number 
 of other gases, exercise a peculiar, and, in general, an 
 injurious influence upon living plants. Is it then, prob- 
 able, that oxygen, one of the most energetic agents 
 in nature, should remain without influence on plants 
 when one of their peculiar processes of assimilation has 
 ceased ? 
 
 It is true, that the decomposition of carbonic acid is 
 arrested by absence of light. But then, namely, at 
 night, a true chemical process commences, in conse- 
 quence of the action of the oxygen in the air, upon the 
 organic substances composing the leaves, blossoms, and 
 fruit. This process is not at all connected wiih the 
 life of the vegetable organism, because it goes on in a 
 dead plant exactly as in a living one. 
 
 The substances composing the leaves of different 
 
 / 
 
 \ 
 
80 OF THE ASSIMILATION OF CARBON. 
 
 plants being known, it is a matter of the greatest ease 
 and certainty, to calculate which of them, during life, 
 should absorb most oxygen by chemical action, when 
 the influence of light is withdrawn. 
 
 The leaves and green parts of all plants, containing 
 volatile oils or volatile constituents in general, which 
 change into resin by the absorption of oxygen, should 
 absorb more than other parts which are free from such 
 substances. Those leaves, also, which contain either 
 the constituents of nut-galls, or compounds, in which 
 nitrogen is present, ought to absorb more oxygen than 
 those which do not contain such matters. The correct- 
 ness of these inferences has been distinctly proved by 
 the observations of De Saussiire ; for, whilst the taste- 
 less leaves of the Agave Jlmcricana absorb only 0.3 of 
 their volume of oxygen, in the dark, during 24 hours, 
 the leaves of the Pinus Abies, which contain volatile 
 and resinous oils, absorb 10 times, those of the Quercus 
 Robur containing tannic acid 14 times, and the balmy 
 leaves of the Populus nlba 21 times that quantity. 
 This chemical action is shown, very plainly, also in the 
 leaves of the Cotyledon calycinum, the Cocalia Jicoules 
 and others ; for they are sour like sorrel in the morning, 
 tasteless at noon, and bitter in the evening. The for- 
 mation of acids is effected during the night, by a true 
 process of oxidation : these are deprived of their acid 
 properties during the day and evening, and are changed, 
 by separation of a part of their oxygen, into con)pounds 
 containing oxygen and hydrogen, either in the same pro- 
 portions as in water, or even with an excess of hydro- 
 gen, which is the composition of all tasteless and bitter 
 substances. 
 
 Indeed, the quantity of oxygen absorbed could be 
 
INFLUENCE OF THE SHADE ON PLANTS. 81 
 
 estimated pretty nearly, by the different periods, wliich 
 the green leaves of plants require to undergo alteration 
 in color, by the influence of the atmosphere. Those 
 which continue longest green, will abstract less oxygen 
 from the air in an equal space of time, than those, the 
 constituent parts of which suffer a more rapid change. 
 It is found, for example, that the leaves of the Ilex aqui- 
 folhim, distinguished by the durability of their color, 
 absorb only 0.86 of their volume of oxygen gas, in the 
 same time that the leaves of the poplar absorb 8, and 
 those of the beech 9| times their volume ; both the beech 
 and poplar being remarkable for the rapidity and ease 
 with which the color of their leaves changes. 
 
 When the green leaves of the poplar, the beech, the 
 oak, or the holly, are dried under the air-pump, with ex- 
 clusion of light, then moistened with water, and placed 
 under a glass globe filled with oxygen ; they are found to 
 absorb that gas in proportion as they change in color. 
 The chemical nature of this process is thus completely 
 established. The diminution of the gas which occurs, 
 can only be owing to the union of a large proportion of 
 oxygen with those substances which are already in the 
 state of oxides, or to the oxidation of the hydrogen, in 
 those vegetable compounds which contain it in excess. 
 The fallen brown or yellow leaves of the oak contain, 
 no longer, tannin, and those of the poplar no balsamic 
 constituents. 
 
 The property which green leaves possess, of absorb- 
 ing oxygen, belongs also to fresh wood, whether taken 
 from a twig, or from the interior of the trunk of a tree. 
 When fine chips of such wood are placed in a moist 
 condition, under a jar filled with oxygen, the gas is seen 
 to diminish in volume. But wood, dried by exposure 
 
82 OF THE ASSIMILATION OF CARBON. 
 
 to the atmosphere and then moistened, converts the oxy- 
 gen into carbonic acid, without change of vohime ; fresh 
 wood, therefore, absorbs most oxygen. 
 
 MM. Petersen and Schodler have shown, by tiie 
 careful elementary analysis of 24 different kinds of wood, 
 that they contain carbon and the elements of water, with 
 the addition of a certain quantity of hydrogen. Oak 
 wood, recently taken from the tree, and diied at 100^ 
 C. (212° F.), contains 49.432 carbon, 6.069 hydrogen, 
 and 44.499 oxygen. 
 
 The proportion of hydrogen, which is necessary to 
 combine with 44.498 oxygen in order to form water, is 
 I of this quantity, namely 5.56 ; it is evident, therefore, 
 that oak wood contains y\ more hydrogen than corre- 
 sponds to this proportion. In Pinus Larix, P. Abies^ 
 and P. Picea, ths excess of hydrogen amounts to i, and 
 in Tilia Europcea to i. The quantity of hydrogen stands 
 in some relation to the specific weight of the wood ; the 
 lighter kinds of wood contain more of it than the heavier. 
 In ebony wood (Diospyros Ebenum) the oxygen and 
 hydrogen are in exactly the same proportion as in water. 
 
 The difference between the composition of the varie- 
 ties of wood, and that of simple woody fibre, depends, 
 unquestionably, upon the presence of constituents, in 
 part soluble, and in part insoluble, such as resin and 
 other matters, which contain a large proportion of hydro- 
 gen : the hydrogen of such substances being in the analy- 
 sis of the various woods superadded to tiiat of the true 
 woody fibre. 
 
 It has previously been mentioned, that mouldering oak 
 wood contains carbon and the elements of water without 
 any excess of hydrogen. But the proportions of its 
 constituents must, necessarily, have been different, if the 
 
INFLUENCE OF THE SHADE ON PLANTS. 83 
 
 volume of the air had not changed during its decay, 
 because the proportion of hydrogen in those component 
 substances of the wood which contained it in excess is 
 here diminished, and this diminution could only be effect- 
 ed by an absorption of oxygen. 
 
 Most vegetable physiologists have connected the emis- 
 sion of carbonic acid during the night, with the absorp- 
 tion of oxygen from the atmosphere, and have considered 
 these actions as a true process of respiration in plants, 
 similar to that of animals, and like it, having for its re- 
 sult the separation of carbon from some of their con- 
 stituents. This opinion has a very weak and unstable 
 foundation. 
 
 The carbonic acid, which has been absorbed by the 
 leaves and by the roots, together with water, ceases to 
 be decomposed on the departure of daylight ; it is dis- 
 solved in the juices, which pervade all parts of the plant, 
 and escapes every moment through the leaves, in quantity 
 corresponding to that of the water, which evaporates. 
 
 A soil, in which plants vegetate vigorously, contains a 
 certain quantity of moisture, which is indispensably 
 necessary to their existence. Carbonic acid, likewise, 
 is always present in such a soil, whether it has been ab- 
 stracted from the air, or has been generated by the decay 
 of vegetable matter. Rain and well water, as well as 
 that from other sources, invariably contain carbonic acid. 
 Plants during their life constantly possess the power of 
 absorbing by their roots moisture, and, along with it, air, 
 and carbonic acid. Is it, therefore, surprising, that the 
 carbonic acid should be returned, unchanged, to the at- 
 mosphere, along with water, when light (the cause of the 
 fixation of its carbon) is absent .'' 
 
 Neither this emission of carbonic acid nor the absorp- 
 
84 OF THE ASSIMILATION OF CARBON. 
 
 tion of oxygen has any connexion with the process of 
 assimilation ; nor have they the slightest relation to one 
 anotiier ; the one is a purely mechanical, the other a 
 purely chemical process. A cotton wick, enclosed in a 
 lamp, which contains a liquid saturated with carbonic 
 acid, acts exactly in the same manner as a living plant in 
 the night. Water and carbonic acid are sucked up by 
 capillary attraction, and both evaporate from the exterior 
 part of the wick. 
 
 Plants, which live in a soil containing humus, exhale 
 much more carbonic acid during the night than those 
 which grow in dry situations ; they also yield more in 
 rainy than in dry weather. These facts point out to us 
 the cause of the numerous contradictory observations, 
 which have been made with respect to the change im- 
 pressed upon the air by living plants, both in darkness, 
 and in common daylight, but which are unworthy of 
 consideration, as they do not assist in the solution of the 
 main question. 
 
 There are other facts which prove in a decisive manner 
 that plants yield more oxygen to the atmosphere than they 
 extract from it ; these proofs, however, are to be drawn 
 with certainty only from plants which live under water. 
 
 When pools and ditches, the bottoms of which are 
 covered with growing plants, freeze upon their surface in 
 winter, so that the w^ater is completely excluded from the 
 atmosphere, by a clear stratum of ice, small bubbles of 
 gas are observed to escape, continually, during the day, 
 from the points of the leaves and twigs. These bubbles 
 are seen most distinctly when the rays of the sun fall 
 upon the ice ; they are very small at first, but collect 
 under the ice and form large bubbles. They consist of 
 pure oxygen gas. Neither during the night, nor during 
 
NEGLECT OF CHEMISTRY BY BOTANISTS. 85 
 
 the day when the sun does not shine, are they observed 
 to diminish in quantity. The source of this oxygen is 
 the carbonic acid dissolved in the water, which is absorb- 
 ed by the plants, but is again supplied to the water, by 
 the decay of vegetable substances contained in the soil. 
 If these plants absorb oxygen during the night, it can be 
 in no greater quantity than that which the surrounding 
 water holds in solution, for the gas, which has been ex- 
 haled, is not again absorbed. The action of water-plants 
 cannot be supposed to form an exception to a great law 
 of nature, and the less so, as the different action of aerial 
 plants upon the atmosphere is very easily explained. 
 
 The opinion is not new that the carbonic acid of the 
 air serves for the nutriment of plants, and that its carbon 
 is assimilated by them ; it has been admitted, defended, 
 and argued for, by the soundest and most intelligent 
 natural philosophers, namely, by Priestley, Sennehier, 
 De Saussu7-e, and even by Ingenhouss himself. There 
 scarcely exists a theory in natural science, in favor of 
 which there are more clear and decisive arguments. 
 How, then, are we to account for its not being received 
 in its full extent by most other physiologists, for its 
 being even disputed by many, and considered by a few 
 as quite refuted ? 
 
 All this is due to two causes, which we shall now 
 consider. 
 
 One is, that in botany the talent and labor of in- 
 quirers has been wholly spent in the examination of 
 form and structure : -chemistry and physics have not 
 been allowed to sit in council upon the explanation of 
 the most simple processes ; their experience and their 
 laws have not been employed, though the most powerful 
 means of help in the acquirement of true knowledge. 
 
86 OF THE ASSIMILATION OF CABBON. 
 
 They have not been used, because their study has been 
 neglected. 
 
 All discoveries in physics and in chemistry, all ex- 
 planations of chemists, must remain without fruit and 
 useless, because, even to the great leaders in physiology, 
 carbonic acid, ammonia, acids, and bases, are sounds 
 without meaning, words without sense, terms of an un- 
 known language, which awaken no thoughts and no 
 associations. They treat these sciences like the vulgar, 
 who despise a foreign literature in exact proportion to 
 their ignorance of it ; since even when they have had 
 some acquaintance with them, they have not understood 
 their spirit and application. 
 
 Physiologists reject the aid of chemistry in their 
 inquiry into the secrets of vitality, although it alone 
 could guide them in the true path ; they reject chem- 
 istry, because, in its pursuit of knowledge, it destroys 
 the subjects of its investigation ; but they forget that 
 the knife of the anatomist must dismember the body, 
 and destroy its organs, if an account is to be given of 
 their form, structure, and functions. 
 
 When pure potato starch is dissolved in nitric acid, 
 a ring of the finest wax remains. What can be opposed 
 to the conclusion of the chemist, that each grain of 
 starch consists of concentric layers of wax and amylum, 
 which thus mutually protect each other against the 
 action of water and ether ? Can results of this kind, 
 which illustrate so completely both the nature and prop- 
 erties of bodies, be attained by the microscope ? Is it 
 possible to make the gluten in a piece of bread visible 
 in all its connexions and ramifications ? It is impossible 
 by means of instruments ; but if the piece of bread is 
 placed in a lukewarm decoction of malt, the starch, and 
 
OBJECT OF EXPERIMENTS IN PHYSIOLOGY. 87 
 
 the substance called dextrine,* are seen to dissolve like 
 sugar in water, and, at last, nothing remains except the 
 gluten, in the form of a spongy mass, the minute pores 
 of which can be seen only by a microscope. 
 
 Chemistry offers innumerable resources of this kind 
 which are of the greatest use in an inquiry into the 
 nature of the organs of plants, but they are not used, 
 because the need of them is not felt. The most im- 
 portant organs of animals and their functions are known, 
 although they may not be visible to the naked eye. 
 But, in vegetable physiology, a leaf is in every case 
 regarded merely as a leaf, notwithstanding that leaves 
 generating oil of turpentine or oil of lemons must pos- 
 sess a different nature from those in which oxalic acid 
 is formed. Vitality, in its peculiar operations, makes 
 use of a special apparatus for each function of an organ. 
 A rose twig engrafted upon a lemon-tree, does not 
 bring forth lemons but roses. Vegetable physiologists 
 in the study of their science have not directed their 
 attention to that part of it which is most worthy of 
 investigation. 
 
 The second cause of the incredulity with which 
 physiologists view the theory of the nutrition of plants 
 by the carbonic acid of the atmosphere is, that the art 
 
 * Raspail has shown that starch consists of small spherules, each 
 of which has a coating less soluble than its interior; that heat bursts 
 these and lets out their contents, which consist of a gum-like sub- 
 stance, called by Biot dextrine, from its turning the plane of polariza- 
 tion of light to the right hand. It is white, insipid, transparent in 
 thin flakes, and gummy. At 280" F. it becomes brown and acquires 
 the flavor of toasted bread. It is much employed by the French 
 pastry cooks and confectioners ; being reduced to powder it may be 
 introduced into all kinds of pastries, bread, chocolate, «&c. For its 
 preparation &c., see Ure's Dictionary of Jlits and Manufactures, and 
 Webster's Chemistry, 510. 
 
88 OF THE ASSIMILATION OF CARBON. 
 
 of experimenting is not known in physiology, it being 
 an art which can be learned accurately only in the 
 chemical laboratory. Nature speaks to us in a peculiar 
 language, in the language of phenomena ; she answers 
 at all times the questions which are put to her ; and 
 such questions are experiments. An experiment is the 
 expression of a thought : we are near the truth when 
 the phenomenon, elicited by the experiment, corre- 
 sponds to the thought ; while the opposite result shows 
 that the question was falsely stated, and that the con- 
 ception was erroneous. 
 
 The critical repetition of another's experiments must 
 be viewed as a criticism of his opinions ; if the result 
 of the criticism be merely negative, if it do not suggest 
 more correct ideas in the place of those which it is 
 intended to refute, it should be disregarded ; because 
 the worse experimenter the critic is, the greater will be 
 the discrepancy between the results he obtains and the 
 views proposed by the other. 
 
 It is too much forgotten by physiologists, that their 
 duty really is not to refute the experiments of others, 
 nor to show that they are erroneous, but to discover 
 truth, and that alone. It is startling, when we reflect 
 that all the time and energy of a multitude of persons 
 of genius, talent, and knowledge, are expended in en- 
 deavours to demonstrate each other's errors. 
 
 The question whether carbonic acid is the food of 
 plants or not, has been made the subject of experinients 
 with perfect zeal and good faith ; the results have been 
 opposed to that view. But how was the inquiry in- 
 stituted ? 
 
 The seeds of balsamines, beans, cresses, and gourds, 
 were sown in pure Carrara marble, and sprinkled with 
 
CONDITIONS ESSENTIAL TO NUTRITION. 89 
 
 water containing carbonic acid. The seeds sprang, but 
 the plants did not attain to the developement of the third 
 small leaf. In other cases, they allowed the water to 
 penetrate the marble from below, yet, in spile of this, 
 they died. It is worthy of observation, that they lived 
 longer with pure distilled water than with that impreg- 
 nated with carbonic acid ; but still, in this case also, 
 they eventually perished. Other experimenters sowed 
 seeds of plants in flowers of sulphur and sulphate of 
 baryta, and tried to nourish them with carbonic acid, 
 but without success. 
 
 Such experiments have been considered as positive 
 proofs, that carbonic acid will not nourish plants ; but 
 the manner in which they were instituted is opposed to 
 all rules of philosophical inquiry, and to all the laws 
 of chemistry. 
 
 Many conditions are necessary for the life of plants ; 
 those of each genus require special conditions, and 
 should but one of these be wanting, although all the 
 rest be supplied, the plants will not be brought to 
 maturity. The organs of a plant, as well as those of an 
 animal, contain substances of the most different kinds ; 
 some are formed solely of carbon and the elements 
 of water, others contain nitrogen, and in all plants we 
 find metallic oxides in the state of salts. The food 
 which can serve for the production of all the organs 
 of a plant, must necessarily contain all its elements. 
 These most essential of all the chemical qualities of 
 nutriment may be united in one substance, or they may 
 exist separately in several ; in which case, the one con- 
 tains what is wanting in the other. Dogs die although 
 fed with jelly, a substance which contains nitrogen ; 
 they cannot live upon white bread, sugar, or starch, 
 8* 
 
90 OF THE ASSIMILATION OF CARBON. 
 
 if these are given as food, to the exclusion of all other 
 substances. Can it be concluded from this, that these 
 substances contain no elements suited for assimilation .'' 
 Certainly not. 
 
 Vitality is the power which each organ possesses of 
 constantly reproducing itself; /or this it requires a 
 supply of substances which contain the constituent ele- 
 ments of its own substance, and are capable of under- 
 going transformation. All the organs together cannot 
 generate a single element, carbon, nitrogen, or a mefal- 
 lic oxide. 
 
 When the quantity of the food is too great, or is not 
 capable of undergoing the necessary transformation, or 
 exerts any peculiar chemical action, the organ itself is 
 subjected to a change : all poisons act in this manner. 
 The most nutritious substances may cause death. In 
 experiments such as those described above, every con- 
 dition of nutrition should be considered. Besides those 
 matters which form their principal constituent parts, 
 both animals and plants require others, the peculiar 
 functions of which are unknown. These are inorganic 
 substances, such as common salt, the total want of 
 which is in animals inevitably productive of death. 
 Plants, for the same reason, cannot live unless supplied 
 with certain metallic compounds. 
 
 If we knew with certainty that there existed a sub- 
 stance capable, alone, of nourishing a plant and of bring- 
 ing it to maturity, we might be led to a knowledge of 
 the conditions necessary to the life of all plants, by 
 studying its characters and composition. If humus were 
 such a substance, it would have precisely the same 
 value as the only single food which nature has produced 
 for animal organization, namely, milk (Prout). The 
 
CONDITIONS ESSENTIAL TO NUTRITION. 91 
 
 constituents of milk, are cheese or caseine, a compound 
 containing nitrogen in large proportion ; butter, in which 
 hydrogen abounds, and sugar of milk, a substance with 
 a large quantity of hydrogen and oxygen in the same 
 proportion as in water. It also contains in solution, 
 lactate of soda, phosphate of lime, and common salt ; 
 and a peculiar aromatic product exists in the butter, 
 called butric acid. The knowledge of the composition 
 of milk is a key to the conditions necessary for the pur- 
 poses of nutrition of all animals. 
 
 All substances which are adequate to the nourishment 
 of animals, contain those materials united, though not 
 always in the same form ; nor can any one be wanting, 
 for a certain space of time, without a marked effect on 
 the health being produced. The employment of a sub- 
 stance as food, presupposes a knowledge of its capacity 
 of assimilation, and of the conditions under which this 
 takes place. 
 
 A carnivorous animal dies in the vacuum of an air- 
 pump, even though supplied with a superabundance of 
 food ; it dies in the air, if the demands of its stomach 
 are not satisfied ; and it dies in pure oxygen gas, how- 
 ever lavishly nourishment be given to it. Is it hence to 
 be concluded, that neither flesh, nor air, nor oxygen, is« 
 fitted to support life ? Certainly not. 
 
 From the pedestal of the Trajan column at Rome, we 
 might chisel out each single piece of stone, if, upon the 
 extraction of the second, we replaced the first. But 
 could we conclude from this, that the column was sus- 
 pended in the air, and not supported by a single piece 
 of its foundation .'' Assuredly not. Yet the strongest 
 proof would have been given, that each portion of the 
 
92 OF THE ASSIMILATION OF CARBON. 
 
 pedestal could be removed without the downfall of the 
 column. 
 
 Animal and vegetable physiologists, however, come 
 to such conclusions with respect to the process of as- 
 similation. They institute experiments without being 
 acquainted with the circumstances necessary for the con- 
 tinuance of life, — with the qualities and proper nutri- 
 ment of the animal or plant on which they operate, — 
 or with the nature and chemical constitution of its or- 
 gans. These experiments are considered by them as 
 convincing proofs, whilst they are fitted only to awaken 
 pity. 
 
 Is it possible to bring a plant to maturity by means of 
 carbonic acid and water, without the aid of some sub- 
 stance containing nitrogen, which is an essential constit- 
 uent of the sap, and indispensable for its production ? 
 Must the plant not die, however abundant the supply of 
 carbonic acid may be, as soon as the first small leaves 
 have exhausted the nitrogen contained in the seeds ? 
 
 Can a plant be expected to grow in Carrara marble, 
 even when an azotized substance is supplied to it, but 
 when the marble is sprinkled with an aqueous solution 
 of carbonic acid, which dissolves the lime and forms 
 supercarbonate of lime .'' A plant of the family of the 
 Plumbogine^, upon the leaves of which fine hornlike, or 
 scaly processes of crystallized carbonate of lime are 
 formed, might, perhaps, attain maturity under such cir- 
 cumstances ; but these experiments alone are sufficient 
 to prove, that cresses, gourds, and balsamines, cannot 
 be nourished by supercarbonate of lime, in the absence 
 of matter containing nitrogen. We may indeed con- 
 clude, that the salt of lime acts as a poison, since the 
 
CONDITIONS ESSENTIAL TO NUTRITION. 93 
 
 development of plants will advance further in pure 
 water, when lime and carbonic acid are not used. 
 
 Moist flowers of sulphur attract oxygen from the at- 
 mosphere and become acid. Js it possible that a plant 
 can grow and flourish in presence of free sulphuric acid, 
 with no other nourishment than carbonic acid ? It is 
 true, the quantity of sulphuric acid formed thus in hours, 
 or in days, may be small, but the property of each par- 
 ticle of the sulphur to absorb oxygen and retain it, is 
 present every moment. 
 
 When it is known that plants require moisture, car- 
 bonic acid, and air, should we choose, as the soil for 
 experiments on their growth, sulphate of barytes, which, 
 from its nature and specific gravity, completely prevents 
 the access of air ? 
 
 All these experiments are valueless for the decision 
 of any question. It is absurd to take for them any soil 
 at mere hazard, as long as we are ignorant of the func- 
 tions performed in plants by those inorganic substances 
 which are apparently foreign to them. It is quite im- 
 possible to mature a plant of the family of the Graminea, 
 or of the Equisetacea, the solid framework of which 
 contains silicate of potash, without silicic acid and pot- 
 ash, or a plant of the genus Oxalis without potash, or 
 saline plants such as the saltworts (Salsola and Salicor- 
 7iia), without chloride of sodium, or at least some salt of 
 similar properties. All seeds of the Gramlnece contain 
 phosphate of magnesia ; the solid parts of the roots of 
 the althcea contain more phosphate of lime than woody 
 fibre. Are these substances merely accidentally pres- 
 ent .'' A plant should not be chosen for experiment, 
 when the matter which it requires for its assimilation is 
 not well known. 
 
94 ON THE ASSIMILATION OF CARBON. 
 
 What value now can be attached to experiments in 
 which all those matters which a plant requires in the 
 process of assimilation, besides its mere nutriment, have 
 been excluded with the greatest care ? Can the laws of 
 life be investigated in an organized being which is dis- 
 eased or dying ? 
 
 The mere observation of a wood or meadow is infi- 
 nitely better adapted to decide so simple a question, 
 than all the trivial experiments under a glass globe ; the 
 only difference is, that instead of one plant there are 
 thousands. When we are acquainted with the nature of 
 a single cubic inch of their soil, and know the composi- 
 tion of the air and rain-water, we are in possession of all 
 the conditions necessary to their life. The source of the 
 different elements entering into the composition of plants 
 cannot possibly escape us, if we know in what form 
 they take up their nourishment, and compare its com- 
 position with that of the vegetable substances which 
 compose their structure. 
 
 All these questions will now be examined and dis- 
 cussed. It has been already shown, that the carbon of 
 plants is derived from the atmosphere : it still remains 
 for us to inquire, what power is exerted on vegetation 
 by the humus of the soil and the inorganic constituents 
 of plants, and also to trace the sources of their nitro- 
 gen. 
 
ORIGIN AND ACTION OF HUMUS. 95 
 
 CHAPTER III. 
 
 ON THE ORIGIN AND ACTION OF HUMUS. 
 
 All plants and vegetable structures undergo two 
 processes of decomposition after death. One of these 
 is named fermentation^ the other decay , putrefaction, or 
 eremacausis.* 
 
 Decay is a slow process of combustion, a process, 
 therefore, in which the combustible parts of a plant 
 unite with the oxygen of the atmosphere. 
 
 The decay of woody fibre (the principal constituent 
 of all plants) is accompanied by a phenomenon of a pe- 
 culiar kind. This substance, in contact with air or ox- 
 ygen gas, converts the latter into an equal volume of 
 carbonic acid, and its decay ceases upon the disappear- 
 
 * The word eremacausis was proposed by the author some time 
 since, in order to explain the true nature of putrefaction ; it is com- 
 pounded from fi^ifia, slow, and xaZfis, combustion. — Tr. 
 
 Eremacausis is the art of gradual combination of the combustible 
 elements of a body wilh the oxygen of the air; a slow combustion or 
 oxidation. 
 
 The conversion of wood into humus, the formation of acetic acid 
 out of alcohol, nitrification, and numerous other processes, are of this 
 nature. Vegetable juices of every kind, parts of animal and vegetable 
 substances, moist sawdust, blood, &c., cannot be exposed to the air, 
 without suffering immediately a progressive change of color and prop- 
 erties, during which oxygen is absorbed. These changes do not take 
 place when water is excluded, or when the substances are exposed to 
 the temperature of 32°, and diffeient bodies require different degrees 
 of heat, in order to effect the absorption of oxygen, and, consequently, 
 their eremacausis. The property of suffering this change is possessed 
 in the highest degree by substances which contain nitrogen. Liebig. 
 Org. Chcm. Part 2d. 
 
96 ORIGIN AND ACTION OF HUMUS. 
 
 ance of the oxygen. If the carbonic acid is removed, 
 and oxygen replaced, its decay recomnaences, that is, it 
 again converts oxygen into carbonic acid. Woody fibre 
 consists of carbon and the elements of water ; and if 
 we judge only from the products formed during its de- 
 composition, and from those formed by pure charcoal, 
 burned at a high temperature, we might conclude that 
 the causes were the same in both : the decay of woody 
 fibre proceeds, therefore, as if no hydrogen or oxygen 
 entered into its composition.* 
 
 A very long time is required for the completion of 
 this process of combustion, and the presence of water 
 is necessary for its maintenance : alkalies promote it, 
 but acids retard it ; all antiseptic substances, such as 
 sulphurous acid, the mercurial salts, empyreumatic oils, 
 &c., cause its complete cessation. 
 
 Woody fibre, in a state of decay, is the substance 
 called humus. \ 
 
 * In the appendix to the Third Report of the Mgriculture of Massa- 
 chusetts, 1840, Dr. S. L. Dana adduces the following example, to show 
 that even a moist plant will not decay, if air is excluded. A piece of 
 a while birch tree was taken from a depth of twenty-five feet below 
 the surface, in Jjowell. " It must have been inhuirred there prob- 
 ably before the creation of man, yet this most perishable of all wood 
 is nearly as sound as if cut from the forest last fall." 
 
 t The humic acid of chemists is a product of the decomposition of 
 humus by alkalies ; it does not exist in the humus of vegetable physi- 
 ologists, — L. 
 
 The product of the decay of vegetable matters has usually been 
 called vegetable mould, a term which Dr. Jackson prefers to retain. 
 This mould he finds highly charged with carbonic acid, and also to 
 contain man}' other acids. The decay of wood produces similar re- 
 sults. 
 
VEGETABLE MOULD. 97 
 
 VEGETABLE MOULD. 
 
 The term vegetable mould, in its general signification, 
 is applied to a mixture of disintegrated minerals, with 
 the remains of animal and vegetable substances. It may 
 be considered as earth in which humus is contained in a 
 state of decou)position. lis action upon the air has 
 been fully investigated by Ingenhouss and De Saussure. 
 
 When moist vegetable mould is placed in a vessel full 
 of air, it extracts the oxygen therefrom with greater 
 rapidity than decayed wood, and replaces it by an equal 
 volume of carbonic acid. When this carbonic acid is 
 removed and fresh air admitted, the same action is re- 
 peated. 
 
 Cold water dissolves only to.Ioo^J^ of its own weight 
 of vegetable mould ; and the residue left on its evapora- 
 tion consists of common salt with traces of sulphate of 
 potash and lime, and a minute quantity of organic matter, 
 for it is blackened when heated to redness. Boiling 
 water extracts several substances from vegetable mould, 
 and acquires a yellow or yellowish brown color, which is 
 dissipated by absorption of oxygen from the air, a black 
 flocculent deposit being formed. When the colored so- 
 lution is evaporated, a residue is left which becomes 
 black on being heated to redness, and afterwards yields 
 carbonate of potash when treated with water. 
 
 A solution of caustic potash becomes black when 
 placed in contact with vegetable mould, and the addition 
 of acetic acid to the colored solution causes no precipi- 
 tate or turbidity. But dilute sulphuric acid throws down 
 
 * From the Second Part of the original work. 
 
 9 
 
98 DECAY OP WOODY FIBRE. 
 
 a light flocculent precipitate of a brown or black color, 
 from which the acid can be removed with difficulty by 
 means of water. When this precipitate, after having 
 been washed with water, is brought whilst still moist 
 under a receiver filled with oxygen, the gas is absorbed 
 with great rapidity ; and the same thing takes place when 
 the precipitate is dried in the air. In the perfectly dry 
 state it has entirely lost its solubility in water, and even 
 alkalies dissolve only traces of it. 
 
 It is evident, therefore, that boiling water extracts a 
 matter from vegetable mould, which owes its solubility to 
 the presence of the alkaline salts contained in the remains 
 of plants. This substance is a product of the incom- 
 plete decay of woody fibre. Its composition is interme- 
 diate between woody fibre and humus into which it is 
 converted, by being exposed in a moist condition to the 
 action of the air. 
 
 The conversion of woody fibre into the substances 
 termed humus and mould is, on account of its influence 
 on vegetation, one of the most remarkable processes of 
 decomposition which occur in nature. 
 
 Decay is not less important in another point of view ; 
 for, by means of its influence on dead vegetable matter, 
 the oxygen which plants retained during life is again re- 
 stored to the atmosphere. 
 
 The decomposition of woody fibre is effected in three 
 forms, the results of which are diflerent, so that it is 
 necessary to consider each separately. 
 
 The first takes place when it is in the moist condition, 
 and subject to free, uninterrupted access of air ; the 
 second occurs when air is excluded ; and the third when 
 the wood is covered with water, and in contact with pu- 
 trefying organic matter. 
 
ITS COMPOSITION. 99 
 
 It is known that woody fibre may be kept under 
 water, or in dry air, for thousands of years without suf- 
 fering any appreciable change ; but that when brought 
 into contact with air in the moist condition, it converts 
 the oxygen surrounding it into the same volume of car- 
 bonic acid, and is itself gradually changed into a yellow- 
 ish brown, or black matter, of a loose texture. 
 
 According to the experiments of De Saussure, 240 
 parts of dry sawdust of oak wood convert 10 cubic in- 
 ches of oxygen into the same quantity of carbonic acid, 
 which contains 3 parts, by weight, of carbon ; while 
 the weight of the sawdust is diminished by 15 parts. 
 Hence 12 parts by weight, of water, are at the same 
 time separated from the elements of the wood. 
 
 It has already been mentioned, that pure woody fibre 
 contains carbon and the elements of water. Humus, 
 however, is not produced by the decay of pure woody 
 fibre, but by that of wood which contains foreign soluble 
 and insoluble organic substances, besides its essential 
 constituent. 
 
 The relative proportion of the component elements 
 is, on this account, different in oak wood and in beech, 
 and the composition of both of these differs very much 
 from woody fibre, which is the same in all vegetables. 
 The difference, however, is so trivial, that it may be al- 
 together neglected in the consideration of the questions 
 which will now be brought under discussion ; besides, 
 the quantity of the foreign substances is not constant, 
 but varies according to the season of the year. 
 
 According to the careful analysis of Gay-Lussac and 
 Thcnard, 100 parts of oak wood, dried at 212^^ (100^ 
 C), from which all soluble substances had been ex- 
 tracted by means of water and alcohol, contained 52.53 
 
100 DECAY OF WOODY FIBRE. 
 
 parts of carbon, and 47.47 parts of hydrogen and oxy- 
 gen, in the same proportion as they are contained in 
 water. 
 
 Now it has been mentioned that moist wood acts in 
 oxygen gas exactly as if its carbon combined directly 
 with oxygen, and the products of this action are car- 
 bonic acid and humus. 
 
 If the action of the oxygen were confined to the car- 
 bon of the wood, and if nothing but carbon were re- 
 moved from it, the remaining elements would necessarily 
 be found in the humus, unchanged except in the partic- 
 ular of being combined with less carbon. The final 
 result of the action would therefore be a complete dis- 
 appearance of the carbon, whilst nothing but the ele- 
 ments of water would remain. 
 
 But when decaying wood is subjected to examination 
 in different stages of its decay, the remarkable result is 
 obtained, that the proportion of carbon in the different 
 products augments. Consequently, if we did not take 
 into consideration the evolution of carbonic acid under 
 the influence of the air, the conversion of wood into 
 humus might be viewed as a removal of the elements of 
 water from the carbon. 
 
 The analysis of mouldered oak wood, which was 
 taken from the interior of the trunk of an oak, and pos- 
 sessed a chocolate brown color and the structure of 
 wood, showed that 100 parts of it contained 53.36 parts 
 of carbon, and 46.44 parts of hydrogen and oxygen in 
 the same relative proportions as in water. From an 
 examination of mouldered wood of a light brown color, 
 easily reducible to a fine powder, and taken from an- 
 other oak, it appeared that it contained 56.211 carbon 
 and 43.789 water. 
 
TIME REQUIRED. 101 
 
 These indisputable facts point out the similarity of 
 the decay of wood, with the slow combustion or oxida- 
 tion of bodies which contain a large quantity of hydro- 
 gen. Viewed as a kind of combustion, it would indeed 
 be a very extraordinary process, if the carbon combined 
 directly with the oxygen ; for it would be a combustion 
 in which the carbon of the burning body augmented 
 constantly, instead of diminishing. Hence it is evident 
 that it is the hydrogen which is oxidized at the expense 
 of the oxygen of the air ; while the carbonic acid is 
 formed from the elements of the wood. Carbon never 
 combines at common temperatures with oxygen, so as 
 to form carbonic acid. 
 
 In whatever stage of decay wood may be, its elements 
 must always be capable of being represented by their 
 equivalent numbers. 
 
 The following formula illustrates this fact with great 
 clearness : 
 
 C36 H22 022, — oak wood, according to Gay-Lussac and Thenard* 
 C35 H20 O20, — humus from oak wood (Meyer) A 
 C34H18 018,— " " {Dr.WiWj.X 
 
 Tt is evident from these numbers that for every two 
 equivalents of hydrogen which is oxidized, two atoms of 
 oxygen and one of carbon are set free. 
 
 Under ordinary circumstances, woody fibre requires 
 a very long time for its decay ; but this process is of 
 course much accelerated by an elevated temperature and 
 free unrestrained access of air. The decay, on the 
 contrary, is much retarded by absence of moisture, and 
 
 * The calculation gives 52.5 carbon, and 47.5 water, 
 t The calculation gives 54 carbon and 46 water. 
 X The calculation gives 56 carbon and 44 water. 
 9* 
 
102 DECAY OF WOODY FIBRE. 
 
 by the wood being surrounded with an atmosphere of 
 carbonic acid, which prevents the access of air to the 
 decaying matters. 
 
 Sulphurous acid, and all antiseptic substances, arrest 
 the decay of woody fibre. It is well known that corro- 
 sive sublimate is employed for the purpose of protecting 
 the timber of ships from decay ; it is a substance which 
 completely deprives vegetable or animal matters, the 
 most prone to decomposition, of their property of en- 
 tering into fermentation, putrefaction, or decay. 
 
 But the decay of woody fibre is very much accelerat- 
 ed by contact with alkalies or alkaline earths ; for these 
 enable substances to absorb oxygen, which do not pos- 
 sess this power themselves ; alcohol, gallic acid, tannin, 
 the vegetable coloring matters and several other sub- 
 stances, are thus affected by them. Acids produce quite 
 an opposite effect ; they greatly retard decay. 
 
 Heavy soils, consisting of loam, retain longest the 
 most important condition for the decay of the vegetable 
 matter contained in it, viz. water ; but their impermea- 
 ble nature prevents contact with the air. 
 
 In moist sandy soils, particularly such as are compos- 
 ed of a mixture of sand and carbonate of lime, decay 
 proceeds very quickly, it being aided by the presence 
 of the slightly alkaline lime. 
 
 Now let us consider the decay of woody fibre during 
 a very long period of time, and suppose that its cause is 
 the gradual removal of the hydrogen in the form of 
 water, and the separation of its oxygen in that of car- 
 bonic acid. It is evident that if we subtract from the 
 formula C36, H22, 022, the 22 equivalents of oxygen, 
 with 11 equivalents of carbon, and 22 equivalents of hy- 
 drogen, which are supposed to be oxidized by the oxy- 
 
DECAY OF WOODY FIBRE. 103 
 
 gen of the air, and separated in the form of water ; then 
 from 1 atom of oak wood, 25 atoms of pure carbon will 
 remain as the final product of the decay. In other 
 words, 100 parts of oak, which contain 52.5 parts of 
 carbon, will leave as a residue 37 parts of carbon which 
 must remain unchanged, since carbon does not combine 
 with oxygen at common temperatures. 
 
 But this final result is never attained in the decay of 
 wood under common circumstances ; and for this rea- 
 son, that with the increase of the proportion of carbon 
 in the residual humus, as in all decompositions of this 
 kind, its attraction for the hydrogen, which still remains 
 in combination, also increases, until at length the affinity 
 of oxygen for the hydrogen is equalled, by that of the 
 carbon for the same element. 
 
 In proportion as the decay of woody fibre advances, 
 its property of burning with flame, or in other words, 
 of developing carburetted hydrogen on the application 
 of heat, diminishes. Decayed wood burns without 
 flame ; whence no other conclusion can be drawn, than 
 that the hydrogen, which analysis shows to be present, 
 is not contained in it in the same form as in wood. 
 
 Decayed oak contains more carbon than fresh wood, 
 but its hydrogen and oxygen are in the same proportion. 
 
 We would naturally expect that the flame given out 
 by decayed wood should be more brilliant, in proportion 
 to the increase of its cprbon, but we find, on the con- 
 trary, that it burns like tinder, exactly as if no hydrogen 
 were present. For the purposes of fuel, decayed or 
 diseased wood is of little value, for it does not possess 
 the property of burning with flame, a property upon 
 which the advantages of common wood depend. The 
 hydrogen of decayed wood must consequently be sup- 
 
104 DECAY OF WOODY FIBRE. 
 
 posed to be in the state of water ; for had it any other 
 form, the characters we have described would not be 
 possessed by the decayed wood. 
 
 If we suppose decay to proceed in a liquid, which 
 contains both carbon and hydrogen, then a compound 
 containing still more carbon must be formed, in a man- 
 ner similar to the production of the crystalline colorless 
 napthalin from a gaseous compound of carbon and hy- 
 drogen. And if the compound thus formed were itself 
 to undergo further decay, the final result must be the 
 separation of carbon in a crystalline form. 
 
 Science can point to no process capable of account- 
 ing for the origin and formation of diamonds, except the 
 process of decay. Diamonds cannot be produced by 
 the action of fire, for a high temperature, and the pres- 
 ence of oxygen gas, would call into play their combusti- 
 bility. But there is the greatest reason to believe that 
 they are formed in the humid way, that is, in a liquid, 
 and the process of decay is the only cause to which their 
 formation can with probability be ascribed. 
 
 Amber, fossil resin, and the acids in mellite, are the 
 products of vegetable matter which has suffered decom- 
 position. They are found in wood or brown coal, and 
 have evidently proceeded from the decomposition of sub- 
 stances which were contained in quite a different form in 
 the living plants. They are all distinguished by the pro- 
 portionally small quantity of hydrogen which they con- 
 tain. The acid from the mellite (mellitic acid) con- 
 tains precisely the same proportions of carbon and oxygen 
 as that from amber (succinic acid) ; they differ only in 
 the proportion of their hydrogen. M. Bromeis* found 
 
 * Liebig's Jinnalen, Band xxxiv., Heft 3. 
 
HUMUS EVOLVES CARBONIC ACID. 105 
 
 that succinic acid might be artificially foi'tned by the ac- 
 tion of nitric acid on stearic acid, a true process of ere- 
 macausis ; the experiment was made in this laboratory 
 (Giessen) . 
 
 The property of woody fibre to convert surrounding 
 oxygen gas into carbonic acid diminishes in pioportion as 
 its decay advances, and at last a certain quantity of a 
 brown coaly-looking substance remains, in which this 
 property is entirely wanting. This substance is called 
 mould ; it is the product of the complete decay of woody 
 fibre. Mould constitutes the principal part of all the 
 strata of brown coal and peat. 
 
 Humus acts in the same manner in a soil permeable to 
 air as in the air itself ; it is a continued source of car- 
 bonic acid, which it emits very slowly. An atmosphere 
 of carbonic acid, foimed at the expense of the oxygen 
 of the air, surrounds every particle of decaying humus. 
 The cultivation of land, by tilling and loosening the soil, 
 causes a free and unobstructed access of air. An atmo- 
 sphere of carbonic acid is, therefore, contained in every 
 fertile soil, and is the first and most important food for 
 the young plants which grow in it. 
 
 In spring, when those organs of plants are absent, 
 which nature has appointed for the assumption of nour- 
 ishment from the atmosphere, the component substance 
 of the seeds is exclusively employed in the formation of 
 the roots. Each new radicle fibril which a plant acquires 
 may be regarded as constituting at the same time a mouth, 
 a lung, and a stomach. The roots perform the functions 
 
106 ORIGIN AND ACTION OF HUMUS. 
 
 of the leaves from the first moment of their formation ; 
 they extract from the soil their proper nutriment, namely, 
 the carbonic acid generated by the humus. 
 
 By loosening the soil which surrounds young plants, 
 we favor the access of air, and the formation of carbonic 
 acid ; and on the other hand the quantity of their food is 
 diminished by every difficulty which opposes the renewal 
 of air. A plant itself effects this change of air at a cer- 
 tain period of its growth. The carbonic acid, which 
 protects the undecayed humus from further change, is 
 absorbed and taken away by the fine fibres of the roots, 
 and by the roots themselves ; this is replaced by atmo- 
 spheric air, by which process the decay is renewed, and 
 a fresh portion of carbonic acid formed. A plant at 
 this time receives its food, both by the roots, and by the 
 organs above ground, and advances rapidly to maturity. 
 
 When a plant is quite matured, and when the organs, 
 by which it obtains food from the atmosphere, are formed, 
 the carbonic acid of the soil is no further required. 
 
 Deficiency of moisture in the soil, or its complete 
 dryness, does not now check the growth of a plant, pro- 
 vided it receives from the dew and the atmosphere as 
 much as is requisite for the process of assimilation. 
 During the heat of summer it derives its carbon exclu- 
 sively from the atmosphere. 
 
 We do not know what height and strength nature has 
 allotted to plants ; we are acquainted only with the size 
 which they usually attain. Oaks are shown, both in 
 London and Amsterdam, as remarkable curiosities, which 
 have been reared by Chinese gardeners, and are only one 
 foot and a half in height, although their trunks, barks, 
 leaves, branches, and whole habitus, evince a venerable 
 
GROWTH OF PLANTS. 107 
 
 age. The small turnip, grown at Teltow,* when placed 
 in a soil which yields as much nourishment as it can take 
 up, increases to several pounds in weight. 
 
 The size of a plant is proportional to the surface of 
 the organs xchich are destined to convey food to it. A 
 plant gains another mouth and stomach with every new 
 fibre of root, and every new leaf. 
 
 The power which roots possess of taking up nourish- 
 ment does not cease as long as nutriment is present. 
 When the food of a plant is in greater quantity than its 
 organs require for their own perfect development, the 
 superfluous nutriment is not returned to the soil, but is 
 employed in the formation of new organs. At the side 
 of a cell, already formed, another cell arises ; at the side 
 of a twig and leaf, a new twig and a new leaf are devel- 
 oped. These new parts could not have been formed 
 had there not been an excess of nourishment. The 
 sugar and mucilage produced in the seeds, form the nu- 
 triment of the young plants, and disappear during the de- 
 velopment of the buds, green sprouts, and leaves. 
 . . The power of absorbing nutriment from the atmo- 
 sphere, with which the leaves of plants are endowed, 
 being proportionate to the extent of their surface, every 
 increase in the size and number of these parts is neces- 
 sarily attended with an increase of nutritive power, and 
 a consequent further development of new leaves and 
 branches. Leaves, twigs, and branches, when com- 
 pletely matured, as they do not become larger, do not 
 need food for their support. For their existence as or- 
 gans, they require only the means necessary for the per- 
 
 * Teltow is a village near Berlin, where small turnips are cultivated 
 in a sandy soil ; thej are much esteemed, and weigh rarely above one 
 ounce. 
 
108 TRANSFORMATION OF ORGANIC SUBSTANCES. 
 
 formaiice of the special functions to which they are des- 
 tined by nature ; they do not exist on their own account. 
 
 We know that the functions of the leaves and other 
 green parts of plants are to absorb carbonic acid, and 
 with the aid of light and moisture, to appropriate its car- 
 bon. These processes are continually in operation ; 
 they commence with the first formation of the leaves, 
 and do not cease with their perfect development. But 
 the new products arising from this continued assimilation, 
 are no longer employed by the perfect leaves in their own 
 increase : they serve for the formation of woody fibre, 
 and all the solid matters of similar composition. The 
 leaves now produce sugar, amylin or starch, and acids, 
 which were previously formed by the roots when they 
 were necessary for the development of the stem, buds, 
 leaves and branches of the plant. 
 
 The organs of assimilation, at this period of their 
 life, receive more nourishment from the atmosphere 
 than they employ in their own sustenance, and when 
 the formation of the woody substance has advanced to 
 a certain extent, the expenditure of the nutriment, the 
 supply of which still remains the same, takes a new 
 direction, and blossoms are produced. The functions 
 of the leaves of most plants cease upon the ripening of 
 their fruit, because the products of their action are no 
 longer needed. They now yield to the chemical influ- 
 ence of the oxygen of the air, generally suffer there- 
 from a change in color, and fall off. 
 
 A peculiar " transformation " of the matters con- 
 tained in all plants takes place in the period between 
 blossoming and the ripening of the fruit ; new com- 
 pounds are produced, which furnish constituents of the 
 blossoms, fruit, and seed. An organic chemical " trans- 
 
TRANSFORMATION OF ORGANIC SUBSTANCES. 109 
 
 formation " is the separation of the elements of one or 
 several combinations, and their reunion into two or 
 several others, which contain the same number of ele- 
 ments, either grouped in another manner, or in different 
 proportions. Of two compounds formed in conse- 
 quence of such a change, one remains as a component 
 part of the blossom or fruit, while the other is separated 
 by the roots in the form of excrementitious matter. 
 No process of nutrition can be conceived to subsist in 
 animals or vegetables, without a separation of effete 
 matters. We know, indeed, that an organized body 
 cannot generate substances, but can only change the 
 mode of their combination, and that its sustenance and 
 reproduction depend upon the chemical transformation! 
 of the matters which are employed as its nutriment, and 
 which contain its own constituent elements. 
 
 Whatever we regard as the cause of these transforma- 
 tions, whether the Vital Principle, Increase of Tem- 
 perature, Light, Galvanism, or any other influence, the. 
 act of transformation is a purely chemical process.. 
 Combination and Decomposition can take place only 
 when the elements are disposed to these changes. That 
 which chemists name affinity indicates only the degree 
 in which they possess this disposition. It will be 
 shown, when considering the processes of fermentation 
 and putrefaction, that every disturbance of the mutual 
 attraction subsisting between the elements of a body 
 gives rise to a transformation. The elements arrange 
 themselves according to the degrees of their reciprocal 
 attraction into new combinations, which are incapable 
 of further change, under the same conditions. 
 
 The products of these transformations vary with 
 their causes, that is, with the different conditions on 
 10 
 
110 ORIGIN AND ACTION OF HUMUS. 
 
 which their production depended ; and are as innumera- 
 ble as these conditions themselves. The chemical 
 character of an acid, for example, is its unceasing dis- 
 position to saturation by means of a base ;* this dispo- 
 sition differs in intensity in different acids ; but when it 
 is satisfied, the acid character entirely disappears. The 
 chemical character of a base is exactly the reverse of 
 this, but both an acid and a base, notwithstanding the 
 great difference in their properties, effect, in most 
 cases, the same kind of transformations. 
 
 Hydrocyanic acid (prussic acid) f and water contain 
 
 * Liebig applies the term base to compounds which unite with acids 
 and neutralize their characters. The j>roduct is a salt. When the 
 characters of both acids and bases disappear the compound is neutral. 
 
 Some acids contain oxygen, others hydrogen. Several metals form 
 acids with oxygen ; but the greater number of metallic oxides, are, 
 in their relations, totally different from the acids. They form com- 
 pounds, which, for the most part, are insoluble in water ; those soluble 
 in water have an alkaline taste, and possess the property of restoring 
 the blue color of vegetables, which have been reddened by acids. 
 These also change many vegetable yellows to red or brown. The 
 alkalies are soluble bases. Many salts redden vegetable blues, and 
 others again restore the blue color of vegetables reddened by acids; 
 :n the first instance, the salt possesses an acid ; and in the latter an 
 alkaline reaction. 
 
 A simple body which is capable of forming either an acid or a base, 
 is termed a radical ; a compound radical consists of two or three sim- 
 ple radicals, and comports itself in a similar manner to the simple 
 radicals ; that is, it is capable of forming acids and bases. 
 
 t Cyanogen is considered by Liebig as a compound base, and as 
 such uniting with oxygen, hydrogen, and most other nonmetallic 
 elements and with the metals. Cyanogen gas, or bicarburet of nitro- 
 gen, is a compound of nitrogen and carbon, and was named from its 
 affording a blue color and being an ingredient of Prussian blue. For 
 the method of obtaining it, &c., see Webster's Chemistry, 3d edition, 
 p. 219. 
 
 With hydrogen it constitutes hydrocyanic acid. 
 
NATURE OF ORGANIC CHEMICAL PROCESSES. Ill 
 
 the elements of carbonic acid, ammonia, urea, cyanuric 
 acid, cyanilic acid, oxalic acid, formic acid, melam, 
 ammelin, melamin, azulmin, mellon, hydromellonic acid, 
 allantoin, &c. It is well known, that all these very 
 different substances can be obtained from hydrocyanic 
 acid and the elements of water, by various chemical 
 transformations. 
 
 The whole process of nutrition may be understood 
 by the consideration of one of these transformations. 
 
 Hydrocyanic acid and water, for example, when 
 brought into contact with muriatic acid, are decom- 
 posed into formic acid * and ammonia ; both of these 
 products of decomposition contain the elements of hy- 
 drocyanic acid and water, although in another form, 
 and arranged in a different order. The change results 
 from the strong disposition or struggle of muriatic acid 
 to undergo saturation, in consequence of which the hy- 
 drocyanic acid and water suffer mutual decomposition. 
 The nitrogen of the hydrocyanic acid and the hydrogen 
 of the water unite together and form a base, ammonia, 
 with which the acid unites ; the chemical characters of 
 the acid being at the same time lost, because its desire 
 for saturation is satisfied by its uniting with ammonia. 
 Ammonia itself was not previously present, but only its 
 elements, and the power to form it. The simultaneous 
 decomposition of hydrocyanic acid and water in this 
 instance does not take place in consequence of the 
 chemical affinity of muriatic acid for ammonia, since 
 hydrocyanic acid and water contain no ammonia. An 
 affinity of one body for a second, which does not exist, 
 is quite inconceivable. The ammonia, in this case, is 
 
 * An acid obtained from ants, hence its name. It is now obtained 
 
 from sugar and other vegetable substances. 
 
112 ORIGIN AND ACTION OF HUMUS. 
 
 formed only on account of the existing attractive desire 
 of the acid for saturation. Hence we may perceive 
 how much these modes of decomposition, to which the 
 name of transformations or metamorphoses has been 
 especially applied, differ from the ordinary chemical 
 decompositions. 
 
 In consequence of the formation of ammonia, the 
 other elements of hydrocyanic acid, namely, carbon and 
 hydrogen, unite with the oxygen of the decomposed 
 water, and form formic acid, the elements of this sub- 
 stance with the power of combination being present. 
 Formic acid, here, represents the excrementitious mat- 
 ters ; ammonia, the new substance, assimilated by an 
 organ of a plant or animal. 
 
 Each organ extracts from the food presented to it, 
 what it requires for its own sustenance ; while the re- 
 maining elements, which are not assimilated, combine 
 together and are separated as excrement. The excre- 
 mentitious matters of one organ come in contact with 
 another during their passage through the organism, and 
 in consequence suffer new transformations ; the useless 
 matters rejected by one organ containing the elements 
 for the nutrition of a second and a third organ ; but at 
 last, being capable of no further transformations, they 
 are separated from the system by the organs destined 
 for that purpose. Each part of an organized being is 
 fitted for its peculiar functions. A cubic inch of sul- 
 phuretted hydrogen introduced into the lungs, would 
 cause instant death, but it is formed, under a variety of 
 circumstances, in the intestinal canal without any inju- 
 rious effect.* 
 
 * The danger of breathing carbonic acid gas is well known, but 
 large quantities can be taken into the stomach with impunity and 
 even benefit. 
 
ORGANIC CHEMICAL PROCESSES. 113 
 
 In consequence of such transformations as we have 
 described, excrements are formed of various composi- 
 tion ; some of these contain carbon, in excess ; others 
 nitrogen, and others again hydrogen and oxygen. The 
 kidneys, Hver, and lungs, are organs of excretion ; the 
 first separate from the body all those substances in 
 which a large proportion of nitrogen is contained ; the 
 second, those with an excess of carbon ; and the third, 
 such as are composed principally of oxygen and hydro- 
 gen. Alcohol, also, and the volatile oils which are in- 
 capable of being assimilated, are exhaled through the 
 lungs, and not through the skin. 
 
 Respiration must be regarded as a slow process of 
 combustion or constant decomposition. If it be subject 
 to the laws which regulate the processes of decomposi- 
 tion generally, the oxygen of the inspired air cannot 
 combine directly with the carbon of compounds of that 
 element contained in the blood ; the hydrogen only can 
 combine with the oxygen of the air, or undergo a higher 
 degree of oxidation. Oxygen is absorbed without unit- 
 ing with carbon ; and carbonic acid is disengaged, the 
 carbon and oxygen of which must be derived from mat- 
 ters previously existing in the blood. 
 
 All superabundant nitrogen is eliminated from the 
 body, as a liquid excrement, through the urinary pas- 
 sages ; all solid substances, incapable of further trans- 
 formation, pass out by the intestinal canal, and all gase- 
 ous matters by the lungs. 
 
 We should not permit ourselves to be withheld, by 
 the idea of a vital principle, from considering, in a 
 chemical point of view, the process of the transformation 
 of the food, and its assimilation by the various organs. 
 This is the more necessary, as the views, hitherto held, 
 10* 
 
114 ORIGIN AND ACTION OF HUMUS. 
 
 have produced no results, and are quite incapable of 
 useful application. 
 
 Is it truly vitality, which generates sugar in the germ 
 for the nutrition of young plants, or which gives to the 
 stomach the power to dissolve, and to prepare for as- 
 similation all the matter introduced into it ? A decoc- 
 tion of malt possesses as little power to reproduce itself, 
 as the stomach of a dead calf ; both are, unquestionably, 
 destitute of life. But when amylin or starch is intro- 
 duced into a decoction of malt, it changes, first into a 
 gummy-like matter, and lastly into sugar. Hard boiled 
 albumen, and muscular fibre can be dissolved in a de- 
 coction of a calf's stomach, to which a few drops of 
 muriatic acid have been added, precisely as in the stom- 
 ach itself.* (Schwann, Schulz.) 
 
 The power, therefore, to effect transformations, does 
 not belong to the vital principle ; each transformation is 
 owing to a disturbance in the attraction of the elements 
 of a compound, and is consequently a purely chemical 
 process. There is no doubt, that this process takes 
 place in another form, from that of the ordinary decom- 
 position of salts, oxides, or sulphurets. But is it the 
 fault of chemistry, that physiology has hitherto taken no 
 notice of this new form of chemical action .'' 
 
 Physicians are accustomed to administer whole ounces 
 of borax to patients suffering under urinary calculi, when 
 it is known, that the bases of all alkaline salts, formed by 
 organic acids, are carried through the urinary passages 
 in the form of alkaline carbonates capable of dissolving 
 
 * This remarkable action has been completely confirmed in this 
 laboratory (Giessen), by Dr. Vogel, a highly distinguished young 
 physiologist. — L. 
 
VITAL PRINCIPLE. 115 
 
 calculi (Wohler). Is this rational? The medical re- 
 ports state, that upon the Rhine, where so much cream 
 of tartar is consumed in wine, the only cases of calcu- 
 lous disorders are those which are imported from other 
 districts. We know that the uric acid calculus is 
 transformed into the mulberry calculus, (which contains 
 oxalic acid,) when patients suffering under the former 
 exchange the town, for the country, where less animal 
 and more vegetable food is used. Are all these circum- 
 stances incapable of explanation ? 
 
 The volatile oil of the roots of valerian may be ob- 
 tained from the oil generated during the fermentation of 
 potatoes (Dumas), and the oil of the Spircea uhnoria 
 from the crystalline matter of the bark of the willow 
 (Piria). We are able to form in our laboratories, 
 formic acid, oxalic acid, urea, and the crystalline sub- 
 stances existing in the liquid of the allantois of the cow, 
 all products, it is said, of the vital principle. We see, 
 therefore, that this mysterious principle has many rela- 
 tions in common with chemical forces, and that the 
 latter can indeed replace it. What these relations 
 are, it remains for physiologists to investigate. Truly, 
 it would be extraordinary, if this vital principle, which 
 uses every thing for its own purposes, had allotted no 
 share to chemical forces, which stand so freely at its 
 disposal. We shall obtain that which is attainable in a 
 rational inquiry into nature, if we separate the actions 
 belonging to chemical powers, from those which are 
 subordinate to other influences. But the expression, 
 " vital principle," must, in the mean time, be consider- 
 ed as of equal value with the terms specific or dynamic 
 in medicine : every thing is specific which we cannot 
 
116 ORIGIN AND ACTION OF HUMUS. 
 
 explain, and dynamic is the explanation of all which we 
 do not understand. 
 
 Transformations of existing compounds are constant- 
 ly taking place during the whole life of a plant, in conse- 
 quence of which, and as the results of these trans-* 
 formations, there are produced gaseous matters which 
 are excreted by the leaves and blossoms, solid excre- 
 ments deposited in the bark, and fluid soluble substances 
 which are eliminated by the roots. Such secretions are 
 most abundant immediately before the formation and 
 during the continuance of the blossoms ; they diminish 
 after the development of the fruit. Substances, con- 
 taining a large proportion of carbon, are excreted by the 
 roots and absorbed by the soil. Through the expulsion 
 of these matters unfitted for nutrition, therefore, the soil 
 receives again the greatest part of the carbon, which it 
 had at first yielded to the young plants as food, in the 
 form of carbonic acid. 
 
 The soluble matter, thus acquired by the soil, is still 
 capable of decay and putrefaction, and by undergoing 
 these processes furnishes renewed sources of nutrition 
 to another generation of plants ; it becomes humus. 
 The leaves of trees, which fall in the forest in autumn, 
 and the old roots of grass in the meadow, are likewise 
 converted into humus by the same influence : a soil re- 
 ceives more carbon in this form, than its decaying hu- 
 mus had lost as carbonic acid. 
 
 Plants do not exhaust the carbon of a soil, in the nor- 
 mal condition of their growth ; on the contrary, they 
 add to its quantity. But if it is true that plants give back 
 more carbon to a soil than they take from it, it is evi- 
 dent that their growth must depend upon the reception 
 of nourishment from the atmosphere. The influence of 
 
ITS USE EXPLAINED. 117 
 
 humus upon vegetation is explained by the foregoing 
 facts, in the most clear and satisfactory manner. 
 
 Humus does not nourish plants, by being taken up 
 and assimilated in its unaltered state, but by presenting 
 a slow and lasting source of carbonic acid which is ab- 
 sorbed by the roots, and is the principal nutriment of 
 young plants at a time when, being destitute of leaves, 
 they are unable to extract food from the atmosphere. 
 
 In former periods of the earth's history, its surface 
 was covered with plants, the remains of which are still 
 found in the coal formations. These plants, — the gigan- 
 tic monocotyledons, ferns, palms, and reeds, belong to a 
 class, to which nature has given the power, by means 
 of an immense extension of their leaves, to dispense 
 with nourishment from the soil. They resemble, in 
 this respect, the plants which we raise from bulbs 
 and tubers, and which live while young upon the sub- 
 stances contained in their seed, and require no food 
 from the soil, when their exterior organs of nutrition are 
 formed. This class of plants is, even at present, ranked 
 amongst those which do not exhaust the soil. 
 
 The plants of every former period are distinguished 
 from those of the present by the inconsiderable devel- 
 opment of their roots. Fruit, leaves, seeds, nearly 
 every part of the plants of a former world, except the 
 roots, are found in the brown coal formation. The 
 vascular bundles, and the perishable cellular tissue, of 
 which their roots consisted, have been the first to suffer 
 decomposition. But when we examine oaks and other 
 trees, which in consequence of revolutions of the same 
 kind occurring in later ages have undergone the same 
 changes, we never find their roots absent. 
 
 The verdant plants of warm climates are very often 
 
118 ORIGIN AND ACTION OP HUMUS. 
 
 such as obtain from the soil only a point of attach- 
 ment and are not dependent on it for their growth. 
 How extremely small are the roots of the Cactus, Se- 
 dum, and Seinpervivum, in proportion to their mass, 
 and to the surface of their leaves ! Again, in the most 
 dry and barren sand, where it is impossible for nourish- 
 ment to be obtained through the roots, we see the 
 milky-juiced plants attain complete perfection. The 
 moisture necessary for the nutrition of these plants is 
 derived from the atmosphere, and when assimilated is 
 secured from evaporation by the nature of the juice it- 
 self. Caoutchouc and wax, which are formed in these 
 plants, surround the water, as in oily emulsions, with an 
 impenetrable envelope by which the fluid is retained, in 
 the same manner as milk is prevented from evaporating, 
 by the skin which forms upon it. These plants, there- 
 fore, become turgid with their juices. 
 
 Particular examples might be cited of plants, which 
 have been brought to maturity, upon a small scale, without 
 the assistance of mould ; but fresh proofs of the accura- 
 cy of our theory respecting the origin of carbon would 
 be superfluous and useless, and could not render more 
 striking, or more convincing, the arguments already ad- 
 duced. It must not, however, be left unmentioned, that 
 common wood charcoal, by virtue merely of its ordinary 
 well-known properties, can completely replace vegetable 
 mould or humus. The experiments of Lukas, which 
 are appended to this work, spare me all further remarks 
 upon its efficacy. 
 
 Plants thrive in powdered charcoal, and may be 
 brought to blossom and bear fruit if exposed to the in- 
 fluence of the rain and the atmosphere ; the charcoal 
 may be previously heated to redness. Charcoal is the 
 
ACTION OF CARBONIC ACID. 119 
 
 nost "indifferent" and most unchangeable substance 
 cnovvn ; it may be kept for centuries without change, 
 md is therefore not subject to decomposition. The only 
 iubstances which it can yield to plants are some salts, 
 ivhich it contains, amongst which is silicate of potash, 
 [t is known, however, to possess the power of condens- 
 ng gases within its pores, and particularly carbonic acid. 
 And it is by virtue of this power that the roots of plants 
 ire supplied in charcoal exactly as in humus, with an at- 
 mosphere of carbonic acid and air, which is renewed as 
 :juickly as it is abstracted. 
 
 In charcoal powder, which had been used for this pur- 
 pose by Lukas for several years, Buchner found a brown 
 substance soluble in alkalies. This substance was evi- 
 dently due to the secretions from the roots of the plants 
 which grew in it. 
 
 A plant placed in a closed vessel in which the air, and 
 therefore the carbonic acid, cannot be renewed, dies 
 exactly as it would do in the vacuum of an air-pump, or 
 in an atmpsphere of nitrogen or carbonic acid, even 
 though its roots be fixed in the richest mould.* 
 
 Plants do not, however, attain maturity, under ordinary 
 
 * A few ^lears since I had an opportunity of observing a striking 
 instance of the effect of carbonic acid upon vegetation in the vol- 
 canic island of St. Michael (Azores). The gas issued from a fissure 
 in the base of a hill of trachyte and tufta from which a level field of 
 some acres extended. This field, at the time of my visit, was in part 
 covered with Indian corn. The corn at the distance of ten or fifteen 
 yards from the fissure, was nearly full grown, and of the usual height, 
 but the height regularly diminished until within five or six feet of the 
 hill, where it attained but a few inches. This effect was owing to the 
 great specific gravity of the carbonic acid, and its spreading upon the 
 ground, but as the distance increased, and it became more and more 
 mingled with atmospheric air, it had produced less and less effect. — W. 
 
120 ASSIMILATION OF HYDROGEN. 
 
 circumstances, in charcoal powder, when they are mois- 
 tened with pure distilled water instead of rain or river 
 water. Rain water must, therefore, contain within it 
 one of the essentials of vegetable life ; and it will be 
 shown, that this is the presence of a compound contain- 
 ing nitrogen, the exclusion of which entirely deprives 
 humus and charcoal of their influence upon vegetation. 
 
 CHAPTER IV. 
 
 ON THE ASSIMILATION OF HYDROGEN. 
 
 The atmosphere contains the principal food of plants 
 in the form of carbonic acid, in the state, therefore, of 
 an oxide. The solid part of plants (woody fibre) con- 
 tains carbon and the constituents of water, or the ele- 
 ments of carbonic acid together with a certain quantity 
 of hydrogen. We can conceive the wood to arise from 
 a combination of the carbon of the carbonic acid with 
 the elements of water, under the influence of solar light. 
 In this case, 72.35 parts of oxygen, by weight, must be 
 separated as a gas for every 27.65 parts of carbon, which 
 are assimilated by a plant. Or, what is much more 
 probable, plants, under the same circumstances, may de- 
 compose water, the hydrogen of which is assimilated 
 along with carbonic acid, whilst its oxygen is separated. 
 If the latter change takes place, 8.04 parts of hydrogen 
 must unite with 100 parts of carbonic acid, in order to 
 form woody fibre, and the 72.35 parts by weight of oxy- 
 gen, which was in combination with the hydrogen of the 
 water, and which exactly corresponds in quantity with 
 
ASSIMILATION OF HYDROGEN. 121 
 
 the oxygen contained in the carbonic acid, must be sep- 
 arated in a gaseous form. 
 
 Each acre of land, which produces 10 centners or 
 cvvts. of carbon, gives annually to the atmosphere 2600 
 Hessian lbs. of free oxygen gas. The specific weight 
 of oxygen is expressed by the number 1.1026, hence 1 
 cubic metre of oxygen weighs 2.864 Hessian lbs., and 
 2600 lbs. of oxygen correspond to 90S cubic metres or 
 58,112 Hessian cubic feet. 
 
 An acre of meadow, wood, or cultivated land in gen- 
 eral, replaces, therefore, in the atmosphere as much oxy- 
 gen as is exhausted by 8 centners of carbon, either in its 
 ordinary combustion in the air or in the respiratory pro- 
 cess of animals. 
 
 It has been mentioned at a former page that pure- 
 woody fibre contains carbon and llie component parts of 
 water, but that ordinary wood contains more hydrogen 
 than corresponds to this proportion. This excess is 
 owing to the presence of the green principle of the leaf,, 
 wax, resin, and other bodies rich in hydrogen. Water 
 must be decomposed, in order to furnish the excess of 
 this element, and consequently one equivalent * of oxygen 
 must be given back to the atmosphere for every equiva- 
 lent of hydrogen appropriated by a plant to the produc- 
 tion of those substances. The quantity of oxygen thus 
 set at liberty cannot be insignificant, for the atmosphere 
 must receive 989 cubic feet of oxygen for every pound 
 of hydrogen assimilated. 
 
 * Equivalent, the combining proportion of a substance. Elemen- 
 tary bodies combine with each other in certain proportional quantities 
 only, which are expressed by numbers, and those numbers are called 
 equivalents, combining-proportions, or projjortions of the elements. 
 The equivalent of a compound body is tlie sum of the equivalents of,' 
 its constituents. See Introduction p. 34. 
 \l 
 
122 ASSIMILATION OF HyDROGEN 
 
 It has already been stated, that a plant, in the forma- 
 tion of woody fibre, must always yield to the atmo- 
 sphere the same proportional quantity of oxygen ; that 
 the volume of this gas set free would be the same 
 whether it were due to the decomposition of carbonic 
 acid or of water. It was considered most probable that 
 the latter was the case. 
 
 From their generating caoutchouc, wax, fats, and 
 volatile oils containing hydrogen in large quantity, and 
 no oxygen, we may be certain that plants possess the 
 property of decomposing water, because from no other 
 body could they obtain the hydrogen of those matters. 
 It has also been proved by the observations o( Humboldt 
 on the fungi, that water may be decomposed without 
 the assimilation of hydrogen. Water is a remarkable 
 combination of two elements,* which have the power to 
 separate themselves from one another, in innumerable 
 processes, in a manner imperceptible to our senses ; 
 while carbonic acid, on the contrary, is only decompo- 
 sable by violent chemical action. 
 
 Most vegetable structures contaiji hydrogen in the 
 form of water, which can be separated as such, and 
 replaced by other bodies ; but the hydrogen which is 
 essential 1o their constitution cannot possibly exist in 
 the state of water. 
 
 All the hydrogen necessary for the formation of an 
 organic compound is supplied to a plant by the decom- 
 position of water. The process of assimilation, in its 
 most simple form, consists in the extraction of hydro- 
 gen from water, and carbon from carbonic acid, in con- 
 
 * Water is composed of two volumes of hydrogen and one volume 
 of oxygen ; by weight, of 1 hydrogen and 8 oxygen. 
 
ATTENDED WITH EVOLUTION OF OXSGEN. 123 
 
 sequence of which, either all the oxygen of the water 
 and carbonic acid is separated, as in the formation of 
 caoutchouc, the volatile oils which contain no oxygen, 
 and other similar substances, or only a part of it is ex- 
 haled. 
 
 The known composition of the organic compounds 
 most generally present in vegetables, enables us to state 
 in definite proportions the quantity of oxygen separated 
 during their formation. 
 
 3G eq. carbonic acid and 22 eq. hydrogen ) ^ ^^^ . ^.^^^ 
 derived from 22 eq. water ) " 
 
 with the separation of 72 eq. oxygen. 
 
 3G eq. carbonic acid and 36 eq. hydrogen ) 'iuaar 
 
 derived from 36 eq. water 5 = > 
 
 with the separation of 72 eq. oxygen. 
 
 3G eq. carbonic acid and 30 eq. hydrogen 7 ^. , 
 
 derived from 30 eq. water 5 ' 
 
 with the separation of 72 eq. oxygen. 
 
 36 eq. carbonic acid and 16 eq. hydrogen) ™ . „ ., 
 
 derived from 16 eq. water ) ' 
 
 with the separation of 64 eq. oxygen. 
 
 36 eq. carbonic acid and 18 eq. hydrogen ) t> , • /j • j 
 
 derived from 18 eq. water 5 — ^'^"'^'"^'^ •*'"'^. 
 
 with the separation of 45 eq. oxygen. 
 
 36 eq. carbonic acid and 18 eq hydrogen ) ., ,. /,-.,, 
 
 derived from 18 eq. water 5 ~ •^^"'*'^ •*"^' 
 
 with the separation of 54 eq. oxygen. 
 
 36 eq. carbonic acid and 24 eq. hydroffen ) /r? /• ^ 
 
 derived from 24 eq. water ^ = Oil of Turpentine, 
 
 with the separation of 84 eq. oxygen. 
 
 It will readily be perceived that the formation of the 
 acids is accompanied with the smallest separation of 
 oxygen ; that the amount of oxygen set free increases 
 with the production of the so named neutral substances, 
 and reaches its maximum in the formation of the oils. 
 
 * An acid discovered in the juice of the apple, and since in the ber- 
 ries of the mountain ash. 
 
124 ASSIMILATION OF HYDROGEN 
 
 Fruits remain acid in cold summers ; while the most 
 numerous trees under the tropics are those which pro- 
 duce oils, caoutchouc, and other substances, containing 
 very little oxygen. The action of sunshine and influ- 
 ence of heat, upon the ripening of fruit, is thus in a 
 certain measure represented by the numbers above 
 cited. 
 
 The green resinous principle of the leaf diminishes 
 in quantity, while oxygen is absorbed, when fruits are 
 ripened in the dark ; red and coloring matters are form- 
 ed ; tartaric, citric, and tannic acids disappear, and are 
 replaced by sugar, amylin, or gum. 6 eq. Tartaric 
 Acid, by absorbing 6 eq. oxygen from the air, form 
 Grape Sugar, with the separation of 12 eq. carbonic 
 acid. 1 eq.' Tannic ^cid, by absorbing 8 eq. oxygen 
 from the air, and 4 eq. water form 1 eq. of Amylin, or 
 starch, with separation of 6 eq. cai'bonic acid. 
 
 We can explain, in a similar manner, the formation 
 of all the component substances of plants, which con- 
 tain no nitrogen, whether they are produced from car- 
 bonic acid and water, with separation of oxygen, or by 
 the conversion of one substance into the other, by the 
 assimilation of oxygen and separation of carbonic acid. 
 
 We do not know in what form the production of 
 these constituents takes place ; in this respect, the rep- 
 resentation of their formation which we have given must 
 not be received in an absolute sense, it being intended 
 only to render the nature of the process more capable 
 of apprehension ; but it must not be forgotten, that if 
 the conversion of tartaric acid into sugar, in grapes, be 
 considered as a fact, it must take place under all cir- 
 cumstances in the same proportions. 
 
 The vital process in plants is, with reference to the 
 
BY THE DECOMPOSITION OF WATER. 125 
 
 point we have been considering, the very reverse of the 
 chemical processes engaged in the formation of salts. 
 Carbonic acid, zinc, and water, when brought into con- 
 tact, act upon one another, and hydrogen is sepafated 
 while a white pulverulent compound is formed, which 
 contains carbonic acid, zinc, and the oxygen of the 
 water. A living plant represents the zinc in this pro- 
 cess : but the process of assimilation gives rise to com- 
 pounds, which contain the elements of carbonic acid 
 and'the hydrogen of water, whilst oxygen is separated. 
 
 Decay has been described above as the great opera- 
 tion of nature, by which that oxygen, which was assimi- 
 lated by plants during life, is again returned to the at- 
 mosphere. During the progress of growth, plants 
 appropriate carbon in the form of carbonic acid, and, 
 hydrogen from the decomposition of water, the oxygen 
 of which is set free, together with a part or all of that 
 contained in the carbonic acid. In the process of 
 putrefaction, a quantity of water, exactly corresponding 
 to that of the hydrogen, is again formed by extraction 
 of oxygen from the air ; while all the oxygen of the 
 organic matter is returned to the atmosphere in the 
 form of carbonic acid. Vegetable matters can emit 
 carbonic acid, during their decay, only in proportion to 
 the quantity of oxygen which they contain ; acids, 
 therefore, yield more carbonic acid than neutral com- 
 pounds ; while fatty acids, resin, and wax, do not 
 putrefy, they remain in the soil without any apparent 
 change. 
 
 The numerous springs which emit carbonic acid in 
 the neighbourhood of extinct volcanoes, must be re- 
 garded as another considerable source of oxygen. Bis- 
 chof calculated that the springs of carbonic acid in the 
 11* 
 
126 SOURCE AND ASSIMILATION 
 
 Eifel (a volcanic district near Coblenz) send into the 
 air every day more than 90,000 lbs. of carbonic acid, 
 corresj3onding to 64,800 lbs. of pure oxygen. 
 
 CHAPTER V. 
 
 ON THE ORIGIN AND ASSIMILATION OF NITROGEN. 
 
 We cannot suppose that a plant would attain matu- 
 rity, even in the richest vegetable mould, without the 
 presence of matter containing nitrogen ; since we know 
 that nitrogen exists in every part of the vegetable struc- 
 ture. The first and most important question to be 
 solved, therefore, is : How and in what form does 
 nature furnish nitrogen to vegetable albumen, and glu- 
 ten, to fruits and seeds ? 
 
 This question is susceptible of a very simple solution. 
 
 Plants, as we know, grow perfectly well in pure 
 ■charcoal, if supplied at the same time with rain-water. 
 Rain-water can contain nitrogen only in two forms, 
 •either as dissolved atmospheric air, or as ammonia. 
 Now, the nitrogen of the air cannot be made to enter 
 into combination with any element except oxygen, even 
 by employment of the most powerful chemical means. 
 We have not the slightest reason for believing that the 
 nitrogen of the atmosphere takes part in the processes 
 of assimilation of plants and animals ; on the contrary, 
 we know that many plants emit the nitrogen, which is 
 absorbed by their roots, either in the gaseous form, or 
 in solution in water. But there are, on the other hand. 
 
OF THE NITROGEN OF PLANTS. 127 
 
 numerous facts, showing, that the formation in plants of 
 substances containing nitrogen, such as gluten, takes 
 place in proportion to the quantity of this element which 
 is conveyed to their roots in the state of ammonia,* 
 derived from the putrefaction of animal matter. 
 
 Ammonia, too, is capable of undergoing such a multi- 
 tude of transformations, when in contact with other 
 bodies, that in this respect it is not inferior to water, 
 which possesses the same property in an eminent degree. 
 It possesses properties which we do not find in any 
 other compound of nitrogen ; when pure, it is extreme- 
 ly soluble in water ; it forms soluble compounds with 
 all the acids ; and when in contact with certain other 
 substances, it completely resigns its character as an 
 alkali, and is capable of assuming the most various and 
 opposite forms. Formate f of ammonia changes, under 
 the influence of a high temperature, into hydrocyanic 
 acid and water, without the separation of any of its ele- 
 ments. Ammonia forms urea,| with cyanic acid,§ and 
 
 * Ammonia is a compound gas consisting of one volume of nitro- 
 gen and three volumes of hydrogen. It is produced during the 
 decomposition of many animal substances. It is given off when sal- 
 ammoniac and lime are rubbed together. It was formerly called 
 volatile alkali. 
 
 t Formic acid is also obtained from sugar and many other vegetable 
 substances; a pound of sugar yields a quantity capable of saturating 
 five or six ounces of carbonate of lime. A process for obtaining it 
 has been given by Emmet in the American Journal, XXXII. p. 140. 
 See details in Webster's Manual of Clicmislrij, 3d edition, p. 374. 
 
 Its composition is carbon 2, water 3. With ammonia and other 
 bases it yields the salts cMed formates. 
 
 X Urea was discovered in urine, being a constituent of uric acid. 
 It contains the elements of cyanate of ammonia (NH4O -f- C4NO). 
 
 § This acid consists of 1 cyanogen and 1 oxygen. See Webster's 
 Chemistry, p. 31)8. 
 
128 SOURCE AND ASSIMILATION 
 
 a series of crystalline compounds, with the volatile oils 
 of mustard and bitter almonds. It changes into splen- 
 did blue or red coloring matters, when in contact with 
 the bitter constituent of the bark of the apple-tree 
 {phloridzin) , with the sweet principle of the Variolaria 
 dealbata (orcin)^ or with the tasteless matter of the 
 Rocella tinctoria (erythrin). All blue coloring mat- 
 ters which are reddened by acids, and all red coloring 
 substances which are rendered blue by alkalies, contain 
 nitrogen, but not in the form of a base. 
 
 These facts are not sufficient to establish the opinion 
 that it is ammonia, which affords all vegetables without 
 exception the nitrogen which enters into the composi- 
 tion of their constituent substances. Considerations of 
 another kind, however, give to this opinion a degree of 
 certainty, which completely excludes all other views of 
 the matter. 
 
 Let us picture to ourselves the condition of a well 
 cultured farm, so large as to be independent of assis- 
 tance from other quarters. On this extent of land there 
 is a certain quantity of nitrogen contained both in the 
 corn and fruit which it produces, and in the men and 
 animals which feed upon them, and also in their excre- 
 ments. We shall suppose this quantity to be known. 
 The land is cultivated without the importation of any 
 foreign substance containing nitrogen. Now, the pro- 
 ducts of this farm must be exchanged every year for 
 money, and other necessaries of life, for bodies, there- 
 fore, which contain no nitrogen. A certain proportion 
 of nitrogen is exported with corn and cattle ; and this 
 exportation takes place every year, without the smallest 
 compensation ; yet after a given number of years, the 
 quantity of nitrogen will be found to have increased. 
 
OF THE NITROGEN OF PLANTS. 129 
 
 Whence, we may ask, comes this increase of nitrogen ? 
 The nitrogen in the excrements cannot reproduce itself, 
 and the earth cannot yield it. Plants, and consequently 
 animals, must, therefore, derive their nitrogen from the 
 atmosphere. 
 
 The last products of the decay and putrefaction of 
 animal bodies present themselves in two different forms. 
 They are in the form of a combination of hydrogen and 
 nitiogen, — ammonia^ in the temperate and cold cli- 
 mates, and in that of a compound, containing oxygen, 
 nitric acid, in the tropics and hot climates. The for- 
 mation of the latter is preceded by the production of the 
 first. Ammonia is the last product of the putrefaction 
 of animal bodies ; nitric acid is the product of the trans- 
 formation of ammonia. A generation of a thousand 
 million men is renewed every thirty years : thousands of 
 millions of animals cease to live, and are reproduced in 
 a much shorter period. Where is the nitrogen which 
 they contained during life .'' There is no question 
 which can be answered with more positive certainty. 
 All animal bodies, during their decay, yield the nitrogen, 
 which they contain to the atmosphere, in the form of 
 ammonia. Even in the bodies buried sixty feet under 
 ground in the churchyard of the £glise des Innocens, at 
 Paris, all the nitrogen contained in the adipocire was in 
 the state of ammonia.* Ammonia is the simplest of all 
 
 * In 1786-7, when this churchyard was cleared out, it was discov- 
 ered that many of the bodies had been converted into a soapy white 
 substance. Fourcroy attempted to prove that the fatty body was an 
 ammoniacal soap, containing phosphate of hme, that the fat was simi- 
 lar to spermaceti and to wax, hence he called it adipocire. Its melt- 
 ing point was 126.5° F. 
 
 For notice of the analysis and opinions of other chemists see Ure's 
 Dictionary of^rts and Manufactures, p. 14. 
 
130 SOURCE AND ASSIMILATION 
 
 the compounds of nitrogen ; and hydrogen is the ele- 
 ment for which nitrogen possesses the most powerful 
 affinity. 
 
 The nitrogen of putrefied animals is contained in the 
 atmosphere as ammonia, in the form of a gas which is 
 capable of entering into combination with carbonic acid, 
 and of forming a volatile salt. Ammonia in its gaseous 
 form as well as all its volatile compounds are of extreme 
 solubility in water. * Ammonia, therefore, cannot re- 
 main long in the atmosphere, as every shower of rain 
 must condense it, and convey it to the surface of the 
 earth. Hence, also, rain-water must, at all times, con- 
 tain ammonia, though not always in equal quantity. It 
 must be greater in summer than in spring or in winter, 
 because the intervals of time between the showers are 
 in summer greater ; and when several wet days occur, 
 the rain of the first must contain more of it than that of 
 the second. The rain of a thunder-storm, after a long 
 protracted drought, ought for this reason to contain the 
 greatest quantity, which is conveyed to the earth at one 
 time. 
 
 But all the analyses of atmospheric air, hitherto made, 
 have failed to demonstrate the presence of ammonia, 
 although according to our view it can never be absent. 
 Is it possible that it could have escaped our most 
 delicate and most exact apparatus .'' The quantity of 
 nitrogen contained in a cubic foot of air is certainly 
 extremely small, but notwithstanding this, the sum of 
 the quantities of nitrogen from thousands and millions of 
 dead animals is more than sufficient to supply all those 
 living at one time with this element. 
 
 * According to Dr. Thomson, water absorbs 780 times its bulk of 
 ammonia. 
 
OF THE NITROGEN OF PLANTS. 131 
 
 From the tension of aqueous vapor at 15° C. (59° 
 F.) = 6.98 lines (Paris measure) and from its known 
 specific gravity at 0° C. (32° F.), it follows that when 
 the temperature of the air is 59^ F. and the height of 
 the barometer 28'', 1 cubic metre or 64 Hessian cubic 
 feet of aqueous vapor are contained in 487 cubic me- 
 tres, or 31,168 cubic feet of air ; 64 feet of aqueous 
 vapor weigh about 1^ lb. Consequently if we suppose 
 that the air saturated with moisture at 59° F. allows all 
 the water which it contains in the gaseous form to fall as 
 rain ; then 1 Hessian pound of rain-water must be ob- 
 tained from every 20,800 cubic feet of air. The whole 
 quantity of ammonia contained in the same number of 
 cubic feet will also be returned to the earth in this one 
 pound of rain-water. But if the 20,800 cubic feet of 
 air contain a single grain of ammonia, then ten cubic 
 inches, the quantity usually employed in an analysis, 
 must contain only 0.000000048 of a grain. This ex- 
 tremely small proportion is absolutely inappreciable by 
 the most delicate and best eudiometer ; * it might be 
 classed among the errors of observation, even were its 
 quantity ten thousand times greater. But the detection 
 of ammonia must be much more easy, when a pound 
 of rain-water is examined, for this contains ail the gas 
 that was diffused through 20,800 cubic feet of air. 
 
 If a pound of rain-water contain only |th of a grain 
 of ammonia, then a field of 40,000 square feet must 
 receive annually upwards of 80 lbs. of ammonia, or 65 
 lbs. of nitrogen ; for, by the observations of Sch'Mcr, 
 
 * A eudiometer is an instrument used in the analysis of the atmo- 
 sphere. It means a measure of purity. It is also used in the analysis 
 of mixtures of gases. Several varieties a'e described in Webster's 
 Manual, p. 137. 
 
132 SOURCE AND ASSIMILATION 
 
 which were formerly alluded to, about 700,000 lbs. of 
 rain fall over this surface in four months, and conse- 
 quently the annual fall must be 2,500,000 lbs. This is 
 much more nitrogen than is contained in the form of 
 vegetable albumen and gluten, in 2650 lbs. of wood, 
 2800 lbs. of hay, or 200 cwt. of beet-root, which are 
 the yearly produce of such a field, but it is less than the 
 straw, roots, and grain of corn which might grow on the 
 same surface, would contain. 
 
 Experiments, made in this laboratory (Giessen) with 
 the greatest care and exactness, have placed the presence 
 of ammonia in rain-water beyond all doubt. It has 
 hitherto escaped observation, because no person thought 
 of searching for it.* All the rain-water employed in 
 this inquiry was collected 600 paces southwest of Gies- 
 sen, whilst the wind was blowing in the direction of the 
 town. When several hundred pounds of it were distilled 
 in a copper still, and the first two or three pounds evapo- 
 rated with the addition of a little muriatic acid, a very 
 distinct crystallization of sal-ammoniac was obtained : the 
 crystals had always a brown or yellow color. 
 
 Ammonia may likewise be always detected in snow- 
 water. Crystals of sal-ammoniac were obtained by 
 evaporating in a vessel with muriatic acid several pounds 
 of snow, which were gathered from the surface of the 
 ground in March, when the snow had a depth of 10 
 inches. Ammonia was set free from these crystals by 
 the addition of hydrate of lime. The inferior layers 
 of snow, which rested upon the ground, contained a 
 quantity decidedly greater than those which formed the 
 surface. 
 
 * It has been discovered by Mr. Hayes in the rain-water in Ver- 
 mont. 
 
OF THE NITROGEN OF PLANTS. 133 
 
 It is worthy of observation, that the ammonia con- 
 tained in rain and snow water, possessed an offensive 
 smell of perspiration and animal excrements, — a fact 
 which leaves no doubt respecting its origin. 
 
 H'dnefeld has proved, that all the springs in Greifs- 
 walcle^ Wick, Eldena, and Kostenhagen, contain CBr- 
 bonate and nitrate of ammonia. Ammoniacal salts have 
 been discovered in many mineral springs in Kissingen 
 and other places. The ammonia of these salts can only 
 arise from the atmosphere.* 
 
 Any one may satisfy himself of the presence of am- 
 monia in rain, by simply adding a little sulphuric or 
 muriatic acid to a quantity of rain-water, and evaporating 
 this nearly to dryness in a clean porcelain basin. The 
 ammonia remains in the residue, in combination with the 
 acid employed ; and may be detected either by the 
 addition of a little chloride of platinum, or more simply- 
 by a little powdered lime, which separates the ammonia,, 
 and thus renders its peculiar pungent smell sensible.. 
 The sensation which is perceived upon moistening the- 
 hand with rain-water, so different from that produced by 
 pure distilled water, and to which the term softness is 
 vulgarly applied, is also due to the carbonate of ammonia 
 contained in the former. f 
 
 The ammonia, which is removed from the atmosphei-e- 
 by rain and other causes, is as constantly replaced by 
 
 * Professor Daubeny, of Oxford, in his Report on Mineral and' 
 Thermal Waters, to the British Association, in 1836, notices the 
 occurrence of ammonia in various springs, and refers its presence- 
 to the decomposition of animal or vegetable substances where the- 
 springs are not connected with volcanic action. 
 
 + A small quantity of ammonia wafer added to what is commonly 
 called hard water, will give it the softness of rain or snow water. 
 
 12 
 
134 SOURCE AND ASSIMILATION 
 
 the putrefaction of animal and vegetable matters. A cer- 
 tain poriion of that which falls with the rain, evaporates 
 again with the water, but another portion is, we suppose, 
 taken up by the roots of plants, and, entering into new 
 combinations in the different organs of assimilation, pro- 
 duces albumen, gluten, quinine, morphia, cyanogen, and 
 a number of otiier compounds containing nitrogen. The 
 chemical characters of ammonia render it capable of 
 entering into such combinations, and of undergoing nu- 
 merous transformations. We have now only to con- 
 sider whether it really is taken up in the form of ammonia 
 by the roots of plants, and in that form applied by their 
 organs to the production of the azotized matters con- 
 tained in them. This question is susceptible of easy 
 solution by well-known facts. 
 
 In the year 1834, I was engaged with Dr. JVilbrand, 
 Professor of Botany in the University of G lessen, in an 
 investigation respecting the quantity of sugar contained 
 in different varieties of maple-trees, which grew upon 
 soils which were not manured. We obtained crystallized 
 sugars from all, by simply evaporating their juices, with- 
 out the addition of any foreign substance ; and we un- 
 expectedly made the observation, that a great quantity 
 of ammonia was emitted from this juice, when mixed 
 with lime, and also from the sugar itself during its refine- 
 ment. The vessels, which hung upon the trees in order 
 to collect the juice, were watched with greater attention, 
 on account of the suspicion that some evil-disposed 
 persons had introduced urine into them, but still a large 
 quantity of ammonia was again found in the form of 
 neutral salts. The juice had no color, and had no re- 
 action on that of vegetables. Similar observations were 
 made upon the juice of the birch-tree ; the specimens 
 
OF THE NITROGEN OF PLANTS. 135 
 
 subjected to experiment were taken from a wood several 
 miles distant from any house, and yet the clarified juice, 
 evaporated with lime, emitted a strong odor of ammonia. 
 
 In the manufactories of beet-root sugar, many thou- 
 sand cubic feel of juice are daily purified with lime, in 
 order to free it from vegetable albumen and gluten, and 
 it is afterwards evaporated for crystallization. Every 
 person, who has entered such a manufactory, must have 
 been astonished at the great quantity of ammonia which 
 is volatilized along with the steam. This ammonia must 
 be contained in the form of an ammoniacal salt, because 
 the neutral juice possesses the same characters as the 
 solution of such a salt in water ; it acquires, namely, an 
 acid reaction during evaporation, in consequence of the 
 neutral salt being converted by loss of ammonia into an 
 acid salt. The free acid which is thus formed is a 
 source of loss to the manufacturers of sugar from beet- 
 root, by changing a part of the sugar into uncrystallizable 
 grape sugar and syrup. 
 
 The products of the distillation of flowers, herbs, and 
 roots, with water, and all extracts of plants made for 
 medicinal purposes, contain ammonia. The unripe, 
 transparent, and gelatinous pulp of the almond and peach 
 emit much ammonia when treated with alkalies. {Robi- 
 quet.) The juice of the fresh tobacco leaf contains 
 ammoniacal salts. The water, which exudes from a cut 
 vine, when evaporated with a few drops of muriatic acid, 
 also yields a gummy deliquescent mass, which evolves 
 much ammonia on the addition of lime. Ammonia ex- 
 ists in every part of plants, in the roots (as in beet-root), 
 in the stem (of the maple-tree), and in all blossoms and 
 fruit in an unripe condition. 
 
 The juices of the maple and birch contain both sugar 
 
136 SOURCE AND ASSIMILATION 
 
 and ammonia, and, therefore, afford all the conditions 
 necessary for the formation of the azotized components 
 of the branches, blossoms, and leaves, as well as of those 
 which contain no azote or nitrogen. In proportion as 
 the development of those parts advances, the ammonia 
 diminishes in quantity, and when they are fully formed, 
 the tree yields no more juice. 
 
 The employment of animal manure in the cultivation 
 of grain, and the vegetables which serve for fodder to 
 cattle, is the most convincing proof that the nitrogen of 
 vegetables is derived from ammonia. The quantity of 
 gluten in wheat, rye, and barley, is very different ; these 
 kinds of grain also, even when ripe, contain this com- 
 pound of nitrogen in very different proportions. Proust 
 found French wheat to contain 12.5 per cent, of gluten ; 
 Vogcl found that the Bavarian contained 24 per cent. ; 
 Davy obtained 19 per cent, from winter, and 24 from 
 summer wheat ; from Sicilian 21, and from Barbary 
 wheat 19 per cent. The meal of Alsace wheat contains, 
 according to Boussingault., 17.3 per cent, of gluten ; 
 that of wheat grown in the " Jardin des Plantes " 26.7, 
 and that of winter wheat 3.33 per cent. Such great 
 differences must be owing to some cause, and this we 
 find in the different methods of cultivation. An increase 
 of animal manure gives rise not only to an increase in 
 the number of seeds, but also to a most remarkable dif- 
 ference in the proportion of the gluten which they con- 
 tain. 
 
 Animal manure, as we shall afterwards show, acts only 
 by the formation of ammonia. One hundred parts of 
 wheat grown on a soil manured with cow-dung (a manure 
 containing the smallest quantity of nitrogen), afforded 
 only 11.95 parts of gluten, and 64.34 parts of amylin, 
 
OF THE NITROGEN OF PLANTS. 137 
 
 or Starch ; whilst the same quantity, grown on a soil 
 manured with human urine, yielded the maximum of glu- 
 ten, namely 35.1 per cent. Putrified urine contains 
 nitrogen in the forms of carbonate, phosphate, and lac- 
 tate of ammonia, and in no other form than that of am- 
 moniacal salts. 
 
 " Putrid urine is employed in Flanders as a manure 
 with the best results. During the putrefaction of urine, 
 ammoniacal salts are formed in large quantity, it may be 
 said exclusively ; for under the influence of heat and 
 moisture urea, the most prominent ingredient of the urine, 
 is converted into carbonate of ammonia. The barren 
 soil on the coast of Peru is rendered fertile by means of 
 a manure called guano^ which is collected from several 
 islands on the South Sea.* Tt is sufficient to add a 
 small quantity of guano to a soil, which consists only of 
 sand and clay, in order to procure the richest crop of 
 maize. The soil itself dues not contain the smallest 
 particle of organic matter, and the manure employed is 
 formed only of urate, phosphate, oxalate, and carbonate 
 of ammonia, together with a few earthy salts." f 
 
 iVmmonia, therefore, must have yielded the nitrogen 
 to these plants. Gluten is obtained not only from corn, 
 but also from grapes and other plants ; but that extracted 
 from the grapes is called vegetable albumen, although it 
 is identical in composition and properties with the ordi- 
 nary gluten. 
 
 * The guano, which forms a sl/atum of several feet in thickness 
 upon the surface of these islands, consists of the putrid excrements 
 of innumerable sea-fowl that remain on them during the breeding 
 season. 
 
 According to Fourcroy and Vauquelin it contains a fourth part of 
 its weight of uric acid, with ammonia and potash. 
 
 t Boussingault, Jinn, de Chim. et de Pkys. t. Ixv. p. 319. 
 
 12* 
 
138 SOURCE AND ASSIMILATION 
 
 It is ammonia which yields nitrogen to the vegetable 
 albumen, the principal constituent of plants ; and it must 
 be ammonia which forms the red and blue coloring mat- 
 ters of flowers. Nitrogen is not presented to wild plants 
 in any other form capable of assimilation. Ammonia, 
 by its transformation, furnishes nitric acid to the tobacco 
 plant, sunflower, Chenopoclium, and Borago officinalis^ 
 when they grow in a soil completely free from nitre. 
 Nitrates are necessary constituents of these plants, which 
 thrive only when ammonia is present in large quantity, 
 and when they are also subject to the influence of the 
 direct rays of the sun, an influeiice necessary to effect 
 the disengagement within their stem and leaves of the 
 oxygen, which shall unite with the ammonia to form nitric 
 acid. 
 
 The urine of men and of carnivorous animals contains 
 a large quantity of nitrogen, partly in the form of phos- 
 phates, partly as urea. Urea is converted during putre- 
 faction into carbonate of ammonia, thai is to say, it takes 
 the form of the very salt which occurs in rain-water. 
 Human urine is the most powerful manure for all vege- 
 tables containing nitrogen ; that of horses and horned 
 cattle contains less of this element, but infinitely more 
 than the solid excrements of these animals. In addition 
 to urea, the urine of herbivorous animals contains hippuric 
 acid,* which is decomposed during putrefaction into 
 benzoic acid f and ammonia. The latter enters into the 
 
 * Rouelle announced the discovery of an acid in the urine of the 
 horse, which he called benzoic, but in 1834 Liebig showed that this 
 was not benzoic acid, but one easily convertible into it, and distin- 
 guished it by the name hippuric, from "vxos, a horse, and alggp, mine. 
 
 t Benzoic acid exists in gum benzoin, »fcc. ; it is formed, according 
 to Liebig, by the oxidation of a supposed base called benziile. Its 
 composition is carbon 14, hydrogen 5, oxygen 2. 
 
OF THE NITROGEN OF PLANTS. 139 
 
 composition of the gluten, but the benzoic acid often 
 remains unchanged : for example, in the Jlnthoxanlhum 
 odoratum (sweet scented spring grass). 
 
 The solid excrements of animals contain comparative- 
 ly very little nitrogen, but this could not be otherwise. 
 The food taken by animals supports them only in so far 
 as it offers elements for assimilation to the various organs, 
 which they may require for their increase or renewal. 
 Corn, grass, and all plants, without exception, contain 
 azotized substances.* The quantity of food, which 
 animals take for their nourishment, diminishes or increases 
 in the same proportion, as it contains more or less of the 
 substances containing nitrogen. A horse may be kept 
 alive by feeding it with potatoes, which contain a very 
 small quantity of nitrogen ; but life thus supported is a 
 gradual starvation ; the animal increases neither in size 
 nor strength, and sinks under every exertion. The 
 quantity of rice which an Indian eats astonishes the Eu- 
 ropean ; but the fact, that rice contains less nitrogen than 
 any other kind of grain, at once explains the circum- 
 stance. f 
 
 * The late Professor Gorliam obtained from Indian corn a substance 
 to which he gave the name Zeine, according to whose analysis it con- 
 tains no nitrogen ; but ammonia has since been obtained from it. 
 
 t According to the analysis of Braconnot {^nn. dc Chim. et de 
 Phys. t. iv. p. 370), this grain is thus constituted. 
 
 Carolina rice. Picdmovt rice. 
 
 Water, . . . 5.00 
 
 7.00 
 
 Starch, .... 85.07 
 
 83 80 
 
 Parenchyma, . . 4.80 
 
 4 80 
 
 Gluten, . . . 3.60 
 
 3 60 
 
 Uncrystallizable sugar, 0.29 
 
 0.05 
 
 Gummy matter approach- ? q yj 
 ing to starch, \ ' 
 
 0.10 
 
 Oil, .... 0.13 
 
 0.25 
 
 Phosphate of lime, . 0.13 
 
 40 
 
 99.73 10000. With 
 
140 SOURCE AND ASSIMILATION 
 
 Now, as it is evident that the nitrogen of the plants 
 and seeds used by animals as food must be employed in 
 the process of assimilation, it is natural to expect that 
 the excrements of these animals will be deprived of it, 
 in proportion to the perfect digestion of the food, and 
 can only contain it when mixed with secretions from the 
 liver and intestines. Under all circumstances, they must 
 contain less nitrogen than the food. When, therefore, a 
 field is manured with animal excrements, a smaller quan- 
 tity of matter containing nitrogen is added to it than has 
 been taken from it in the form of grass, herbs, or seeds. 
 By means of manure, an addition only is made to the 
 nourishment which the air supplies. 
 
 In a scientific point of view, it should be the care of 
 the agriculturist so to employ all the substances contain- 
 ing a large proportion of nitrogen which his farm affords 
 in the form of animal excrements, that they shall serve 
 as nutriment to his own plants. This will not be the 
 case unless those substances are properly distributed 
 upon his land. A heap of manure lying unemployed 
 upon his land would serve him no more than his neigh- 
 bours. The nitrogen in it would escape as carbonate of 
 ammonia into the atmosphere, and a mere carbonaceous 
 residue of decayed plants would, after some years, be 
 found in its place. 
 
 All animal excrements emit carbonic acid and ammo- 
 nia, as long as nitrogen exists in them. In every stage 
 of their putrefaction an escape of ammonia from them 
 may be induced by moistening them with a potash ley ; 
 
 traces of muriate of polasli, phosphate of potash, acetic acid, sulphur, 
 and lime, and potash united to a vegetable alkali. 
 
 Vauquelin was unable to detect any saccharine matter in rice. — 
 Thomson's Organic Chemistry, p. 883. 
 
OF THE NITROGEN OF PLANTS. 141 
 
 the ammonia being apparent to the senses by a peculiar 
 smell, and by the dense white vapor which arises when 
 a solid body moistened with an acid is brought near it. 
 This ammonia evolved from manure is imbibed by the 
 soil either in solution in water, or in the gaseous form, 
 and plants thus receive a larger supply of nitrogen than 
 is afforded to them by the atmosphere. 
 
 But it is much less the quantity of ammonia, yielded 
 to a soil by animal excrements, than the form in which 
 it is presented by them, that causes their great influence 
 on its fertility. Wild plants obtain more nitrogen from 
 the atmosphere in the form of ammonia than they re- 
 quire for their growth, for the water which evaporates 
 through their leaves and blossoms, emits, after some 
 time, a putrid smell, a peculiarity possessed only by 
 such bodies as contain nitrogen. Cultivated plants re- 
 ceive the same quantity of nitrogen from the atmosphere 
 as trees, shrubs, and other wild plants ; but this is not 
 sufficient for the purposes of agriculture. Agriculture 
 differs essentially from the cultivation of forests, inas- 
 much as its principal object consists in the production 
 of nitrogen under any form capable of assimilation ; 
 whilst the object of forest culture is confined principally 
 to the production of carbon. All the various means of 
 culture are subservient to these two main purposes. A 
 part only of the carbonate of ammonia, which is con- 
 veyed by rain to the soil is received by plants, because 
 a certain quantity of it is volatilized with the vapor of 
 water ; only that portion of it can be assimilated which 
 sinks deeply into the soil, or which is conveyed directly 
 to the leaves by dew, or is absorbed from the air along 
 with the carbonic acid. 
 
 Liquid animal excrements, such as the urine with 
 
 1 
 
142 SOURCE AND ASSIMILATEON 
 
 which the solid excrements are impregnated, contain the 
 greatest part of their ammonia in the slate of sahs, in a 
 form, therefore, in which it has completely lost its vola- 
 tility when presented in this condition ; not the smallest 
 portion of the ammonia is lost to the plants, it is all dis- 
 solved by water, and imbibed by their roots. The evi- 
 dent influence of gypsum upon the growth of grasses, — 
 the striking fertility and luxuriance of a meadow upon 
 which it is strewed, — depends only upon its fixing in 
 the soil the ammonia of the atmosphere, which would 
 otherwise be volatilized, with the water which evapo- 
 rates. The carbonate of ammonia contained in rain- 
 water is decomposed by gypsum, in precisely the same 
 manner as in the manufacture of sal-ammoniac. Solu- 
 ble sulphate of ammonia and carbonate of lime are 
 formed ; and this salt of ammonia possessing no volatil- 
 ity is consequently retained in the soil. All the gyp- 
 sum gradually disappears, but its action upon the car- 
 bonate of ammonia continues as long as a trace of it 
 exists. 
 
 The benficial influence of gypsum and of many other 
 salts has been compared to that of aromatics, which in- 
 crease the activity of the human stomach and intestines, 
 and give a tone to the whole system. But plants con- 
 tain no nerves ; we know of no substance capable of 
 exciting them to intoxication and madness, or of lulling 
 them to sleep and repose. No substance can possibly 
 cause their leaves to appropriate a greater quantity of 
 carbon from the atmosphere, when the other constitu- 
 ents which the seeds, roots, and leaves require for their 
 growth are wanting.* The favorable action of small 
 
 * In 1831, I suggested to a well known and most successful culti- 
 
OF THE NITROGEN OF PLANTS. 143 
 
 quantities of aromatics upon man, when mixed with his 
 food, is undeniable, but aromatics are given to plants 
 loithout food to be digested, and still they flourish with 
 greater luxuriance. 
 
 It is quite evident, therefore, that the common view 
 concerning the influence of certain salts upon the growth 
 of plants evinces only ignorance of its cause. 
 
 The action of gypsum or chloride of calcium (bleach- 
 ing salts) really consists in their giving a fixed condi- 
 tion to the nitrogen, — or ammonia which is brought 
 into the soil, and which is indispensable for the nutrition 
 of plants. 
 
 In order to form a conception of the efl^ect of gyp- 
 sum, it may be suflicient to remark that 100 Hess, lbs 
 of burned gypsum fixes as much ammonia in the soil as 
 6250 lbs. of horse's urine f would yield to it, even on the 
 supposition that all the nitrogen of the urea and hippuric 
 acid were absorbed by the plants without the smallest 
 
 vator (Mr. Haggarston),the application of a weak solution of chlorine 
 gas to the soil in which plants were growing. It appeared to act 
 merely as a stimulant, the plants flourished for a time with great lux- 
 uriance, and in some the foliage was remarkable. The leaves of a Pe- 
 largonium (well known as the Washington Geranium) attained the 
 diameter of a foot, but the flowers were by no means equal to those of 
 similar plants cultivated in the usual manner ; the plants soon perish- 
 ed. Probably a supply of nutriment proportioned to the increased de- 
 mand was not supplied. 
 
 The necessity for this supply is now well known, and Pelargoni- 
 ums are now grown with great luxuriance and perfection, both of 
 leaves and flowers, by the free use of "manure water," obtained by 
 steeping horse dung in rain-water. The soil, too, best adapted to 
 the plants is chiefly prepared fiom decayed vegetable matter, derived 
 from decomposed leaves and plants mixed with that from the sods of 
 fields. 
 
 t Th3 urine of the horse contains, according to Four.croy and Vau- 
 quelin, in 1000 parts, — 
 
144 SOURCE AND ASSIMILATION 
 
 loss, in the form of carbonate of ammonia. If we admit 
 with Boussingault,* that the nitrogen in grass amounts 
 to t4o o^ '^^^ weight, then every pound of nitrogen which 
 we add increases the produce of the meadow 100 lbs., 
 and this increased produce of 100 lbs. is effected by the 
 aid of a little more than four pounds of gypsum. 
 
 Water is absolutely necessary to effect the decompo- 
 sition of the gypsum, on account of its difficult solubil- 
 ity, (I part of gypsum requires 400 parts of water for 
 solution,) and also to assist in the absorption of the sul- 
 phate of ammonia by the plants : hence it happens that 
 the influence of gypsum is not observable on dry fields 
 and meadows. 
 
 The decomposition of gypsum by carbonate of am- 
 monia does not take place instantaneously ; on the con- 
 trary, it proceeds very gradually, and this explains why 
 the action of the gypsum lasts for several years. 
 
 The advantage of manuring fields with burned clay 
 and the fertility of ferruginous soils, which have been 
 considered as facts so incomprehensible, may be ex- 
 plained in an equally simple manner. They have been 
 ascribed to the great attraction for water, exerted by 
 dry clay and ferruginous earth ; but common dry arable 
 land possesses this property in as great a degree : and 
 besides, what influence can be ascribed to a hundred 
 pounds of water spread over an acre of land, in a con- 
 dition in which it cannot be serviceable either by the 
 roots or leaves ? The true cause is this : — 
 
 Uiea, .... 
 Hippnrate of soda, 
 Sails and water, . 
 
 1000 " 
 * Boussingault, ^nn. de Chim. et de P/njs. t. Ixiii. p. 243. 
 
 7 
 
 parts. 
 
 24 
 
 <( 
 
 . 979 
 
 >( 
 
OF THE NITROGEN OF PLANTS. 145 
 
 The oxides of iron and alumina are distinguished 
 from all other metallic oxides by their power of forming 
 solid compounds with ammonia. The precipitates ob- 
 tained by the addition of ammonia to salts of alumina or 
 iron are true salts, in which the ammonia is contained as 
 a base. Minerals containing alumina or oxide of iron 
 also possess, in an eminent degree, the remarkable 
 property of attracting ammonia from the atmosphere 
 and of retaining it. Vauquelin^ whilst engaged in the 
 trial of a criminal case, discovered that all the rust of 
 iron contains a certain quantity of ammonia. * Chevalier 
 afterwards found that ammonia is a constituent of all 
 minerals containing iron ; that even hematite, a mineral 
 which is not at all porous, contains one per cent, of it. 
 Bonis showed also, that the peculiar odor observed on 
 moistening minerals containing alumina, is partly owing 
 to their exhaling ammonia. Indeed, gypsum and some 
 varieties of alumina, pipe-clay for example, emit so 
 much ammonia, when moistened with caustic potash,, 
 that even after they have been exposed for two days, lit- 
 mus paper held over them becomes blue. Soils, there- 
 fore, which contain oxides of iron, and burned clay,, 
 must absorb ammonia, an action which is favored by 
 their porous condition ; they further prevent the escape 
 of the ammonia once absorbed, by their chemical prop- 
 erties. Such soils, in fact, act precisely as a mineral 
 acid would do, if extensively spread over their surface ; 
 with this difference, that the acid would penetrate the 
 ground, enter into combination with lime, alumina, and 
 other bases, and thus lose, in a few hours, its property 
 of absorbing ammonia from the atmosphere. 
 
 The ammonia absorbed by the clay or ferruginous ox- 
 13 
 
146 SOURCE OF THE NITROGEN OF PLANTS. 
 
 ides is separated by every shower of rain, and conveyed 
 in solution to the soil. 
 
 Powdered charcoal possesses a similar action, but 
 surpasses all other substances in the power which it pos- 
 sesses of condensing ammonia within its pores, particu- 
 larly when it has been previously heated to redness. 
 Charcoal absorbs 90 times its volume of ammoniacal 
 gas, which may be again separated by simply moistening 
 it with water (De Saussure). Decayed wood approach- 
 es very nearly to charcoal in this power ; decayed oak 
 wood absorbs 72 times its volume, after having been 
 completely dried under the air-pump. We have here 
 an easy and satisfactory means of explaining still further 
 the properties of humus, or wood in a decaying stale. 
 It is not only a slow and constant source of carbonic 
 acid, but it is also a means by which the necessary nitro- 
 gen is conveyed to plants. 
 
 Nitrogen is found in lichens, which grow on basaltic 
 rocks. Our fields produce more of it than we have 
 given them as manure, and it exists in all kinds of soils 
 and minerals which were never in contact with organic 
 substances. The nitrogen in these cases could only 
 have been extracted from the atmosphere. 
 
 We find this nitrogen in the atmosphere in rain-water 
 and in alt kinds of soils, in the form of ammonia, as a 
 product of the decay and putrefaction of preceding gen- 
 erations of animals and vegetables. We find, likewise, 
 that the proportion of azotized matters in plants is aug- 
 mented by giving them a larger supply of ammonia con- 
 veyed in the form of animal manure. 
 
 No conclusion can then have a better foundation than 
 this, that it is the ammonia of the atmosphere which fur- 
 nishes nitrogen to plants. 
 
OF THE INORGANIC CONSTITUENTS OF PLANTS. 147 
 
 Carbonic acid, water and ammonia, contain the ele- 
 ments necessary for the support of animals and vegeta- 
 bles. The same substances are the ultimate products of 
 the chemical processes of decay and putrefaction. All 
 the innumerable products of vitality resume, after death, 
 the original form from which they sprung. And thus 
 death, — the complete dissolution of an existing gener- 
 ation, — becomes the source of life for a new one. 
 
 But another question arises, — Are the conditions al- 
 ready considered the only ones necessary for the life of 
 vegetables ? It will now be shown that they are not. 
 
 CHAPTER VI. 
 
 OP THE INORGANIC CONSTITUENTS OF PLANTS. 
 
 Carbonic acid, water and ammonia, are necessary 
 for the existence of plants, because they contain the ele- 
 ments from which their organs are formed ; but other sub- 
 stances are likewise requisite for the formation of certain 
 organs destined for special functions peculiar to each 
 family of plants. Plants obtain these substances from 
 inorganic nature. In the ashes left after the incineration 
 of plants, the same substances are found, although in a 
 changed condition. 
 
 Many of these inorganic constituents vary according 
 to the soil in which the plants grow, but a certain num- 
 ber of them are indispensable to their development. 
 
 All substances in solution in a soil are absorbed by 
 the roots of plants, exactly as .a sponge imbibes a liquid. 
 
148 OF THE INORGANIC 
 
 and all that it contains, without selection. The sub- 
 stances thus conveyed to plants are retained in greater 
 or less quantity, or are entirely separated when not suited 
 for assimilation. 
 
 Phosphate of magnesia in combination with ammonia 
 is an invariable constituent of the seeds of all kinds of 
 grasses. It is contained in the outer horny husk, and 
 is introduced into bread along with the flour, and also 
 into beer. The bran of flour contains the greatest 
 quantity of it. It is this salt which forms large crys- 
 talline concretions, often amounting to several pounds in 
 weight, in the ccBCum of horses belonging to millers ; and 
 when ammonia is mixed with beer, the same salt sepa- 
 rates as a white precipitate. 
 
 Most plants, perhaps all of them, contain organic acids 
 of very different composition and properties, all of which 
 are in combination with bases, such as potash, soda, lime 
 or magnesia. These bases evidently regulate the for- 
 mation of the acids, for the diminution of the one is 
 followed by a decrease of the other : thus, in the grape, 
 for example, the quantity of potash contained in its juice 
 is less, when it is ripe, than when unripe ; and the acids, 
 under the same circumstances, are found to vary in a 
 similar manner. Such constituents exist in small quan- 
 tity in those parts of a plant in which the process of 
 assimilation is most active, as in the mass of woody fibre; 
 and their quantity is greater in those organs, whose office 
 it is to prepare substances conveyed to them for assimi- 
 lation by other parts. The leaves contain more inor- 
 ganic matters than the branches, and the branches more 
 than the stem. The potato plant contains more potash 
 before blossoming than after it. 
 
 The acids found in the different families of plants are 
 
CONSTITUENTS OF PLANTS. 149 
 
 of various kinds ; it cannot be supposed that their pres- 
 ence and peculiarities are the result of accident. The 
 fumaric and oxalic acids in the liverwort, the kinovic 
 acid in the China nova, the rocellic acid in the Rocella 
 tinctoria, the tartaric acid in grapes, and the numerous 
 other organic acids, must serve some end in vegetable 
 life. But if these acids constantly exist in vegetables, 
 and are necessary to their life, which is incontestable, 
 it is equally certain that some alkaline base is also indis- 
 pensable in order to enter into combination w^ith the 
 acids which are always found in the state of salts. All 
 plants yield by incineration ashes containing carbonic 
 acid ; all therefore must contain salts of an organic 
 acid. 
 
 Now, as we know the capacity of saturation of organic 
 acids to be unchanging, it follows that the quantity of the 
 bases united with them cannot vary, and for this reason 
 the latter substances ought to be considered with the 
 strictest attention both by the agriculturist and physi- 
 ologist. 
 
 We have no reason to believe that a plant in a con- 
 dition of free and unimpeded growth produces more of 
 its peculiar acids than it requires for its own existence ; 
 hence, a plant, on whatever soil it grows, must contain 
 an invariable quantity of alkaline bases. Culture alone 
 will be able to cause a deviation. 
 
 In order to understand this subject clearly, it will be 
 necessary to bear in mind, that any one of the alkaline 
 bases may be substituted for another, the action of all 
 being the same. Our conclusion is, therefore, by no 
 means endangered by the existence of a particular alkali 
 in one plant, which may be absent in others of the same 
 species. If this inference be correct, the absent alkali 
 13* 
 
150 OF THE INORGANIC 
 
 or earth must be supplied by one similar in its mode 
 of action, or in other words, by an equivalent of another 
 base. The number of equivalents of these various bases, 
 which may be combined with a certain portion of acid, 
 must necessarily be the same, and, therefore, the amount 
 of oxygen contained in them must remain unchanged, 
 under all circumstances, and on whatever soil they 
 grow. 
 
 Of course, this argument refers only to those alkaline 
 bases, which in the form of organic salts form constitu- 
 ents of the plants. Now, these salts are preserved in 
 the ashes of plants, as carbonates, the quantity of which 
 can be easily ascertained. 
 
 It has been distinctly shown by the analyses of De 
 Saussure and Berthier, that the nature of a soil exer- 
 cises a decided influence on the quantity of the different 
 metallic oxides contained in the plants, which grow on 
 it ; that magnesia, for example, was contained in the 
 ashes of a pine-tree grown at Mont Breven, whilst it 
 was absent from the ashes of a tree of the same species 
 from Mont La Salle, and that even the proportion of 
 lime and potash was very different. 
 
 Hence it has been concluded (erroneously, I believe), 
 that the presence of bases exercises no particular influ- 
 ence upon the growth of plants ; but even were this 
 view correct, it must be considered as a most remarkable 
 accident, that these same analyses furnish proof for the 
 very opposite opinion. For although the composition 
 of the ashes of these pine-trees was so very different, 
 they contained, according to the analysis of De Saussure, 
 an equal number of equivalents of metallic oxides ; or 
 what is the same thing, the quantity of oxygen contained 
 in all the bases was in both cases the same. 
 
CONSTITUENTS OF PLANTS. 151 
 
 100 parts of the ashes of the pine-tree from Mont 
 
 Breven contained : — * 
 
 Carbonate of Potash . 3.G0 Quantity of oxygen in the Potash 0.41 
 " Lime . 46.34 " " " Lime 7.33 
 
 " Magnesia 0.77 " " " Magnesia 1.27 
 
 Sum of the carbonates 56.71 Sum of the oxygen in the bases 9.01 
 
 100 parts of the ashes of the pine from Mont La Salle 
 
 contained : — f 
 
 Carbonate of Potash . 7.36 Quantity of oxygen in the Potash 0.85 
 " Lime . 51.19 «' " " Lime 8.10 
 
 " MagnesiaOO.no 
 
 Sum of the carbonates 58.55 Sum of the oxygen in the bases 8.95 
 The numbers 9.01 and 8.95 resemble each other as 
 nearly as could be expected even in analyses made for 
 the very purpose of ascertaining the fact above demon- 
 strated which the analyst in this case had not in view. 
 
 Let us now compare Berthier's analyses of the ashes 
 of two fir-trees, one of which grew in Norway, the other 
 in Allevard (departement de I'Isere). One contained 
 50, the other 25 per cent, of soluble salts. A greater 
 difference in the proportion of the alkaline bases could 
 scarcely exist between two totally different plants, and 
 yet even here, the quantity of oxygen in the bases of 
 both was the same. 
 
 100 parts of the ashes of fir-wood from Allevard con- 
 tained according to Berlhier, {A7in. de Chim. et de 
 Phys. t. xxxii. p. 248,) 
 
 Potash and Soda 16.8 in which 3.42 parts must be oxygen. 
 
 Lime . 295 " 8.20 
 
 Magnesia . 3.2 " 1.20 « " 
 
 49.5 12.82 
 
 * 100 parts of this wood gave 1.187 aslies. 
 t 100 parts of this wood gave 1.128 ashes. 
 
152 OF THE INORGANIC 
 
 Only part of the potash and soda in these ashes was 
 in combination with organic acids, the remainder was in 
 the form of sulphates, phosphates, and chlorides. One 
 hundred parts of the ashes contained 3.1 sulphuric acid, 
 4.2 phosphoric acid, and 0.3 hydrochloric acid, which, 
 together, neutralize a quantity of base containing 1.20 
 oxygen. This number therefore must be subtracted 
 from 12.82. The remainder 11.62 indicates the quan- 
 tity of oxygen in the alkaline bases, combined with or- 
 ganic acids, in the fir-wood of Allevard. 
 
 The fir-wood of Norway contained in 100 parts : * 
 
 Potash . 14.1 of which 2.4 parts would be oxygen. 
 
 Soda . 20.7 " 5.3 " " 
 
 Lime . 12.3 " 3.45 " " 
 
 Magnesia . 4.35 " 1.G9 " " 
 
 51.45 12.84 
 
 And if the quantity of oxygen of the bases in combina- 
 tion with sulphuric and phosphorip acid, viz. 1.37, be 
 again subtracted from 12.84, 11.47 parts remain as the 
 amount of oxygen contained in the bases, which were in 
 combination with organic acids. 
 
 These remarkable approximations cannot be acci- 
 dental ; and if further examinations confirm them in 
 other kinds of plants, no other explanation than that 
 already given can be adopted. 
 
 It is not known in what form silica, manganese, and 
 oxide of iron, are contained in plants, but we are cer- 
 tain that potash, soda, and magnesia, can be extracted 
 from all parts of their structure in the form of salts of 
 
 * This calculation is exact only in the case where the quantity of 
 ashes is equal in weight for a given quantity of wood ; the difference 
 cannot, however, be admitted to be so great as to change sensiblj' the 
 above proportions. Berthier has not mentioned the proportion of 
 ashes contained in the wood. — L. 
 
CONSTITUENTS OF PLANTS. 153 
 
 organic acids. The same is the case with lime, when 
 not present as insoluble oxalate of lime. It must here 
 be remembered, that in plants yielding oxalic acid, the 
 acid and potash never exist in the form of a neutral or 
 quadruple salt, but always as a double acid salt, on 
 whatever soil they may grow. The potash in grapes, 
 also, is more frequently found as an acid salt, viz. cream 
 of tartar, than in the form of a neutral compound. As 
 these acids and bases are never absent from plants, and 
 as even the form in which they present themselves is 
 not subject to change, it may be affirmed, that they ex- 
 ercise an important influence on the development of the 
 fruits and seeds, and also on many other functions of the 
 nature of which we are at present ignorant. 
 
 The quantity of alkaline bases existing in a plant also 
 depends evidently on this circumstance of their existing 
 only in the form of acid salts, for the capacity of satura- 
 tion of an acid is constant ; and when we see oxalate of 
 lime in the lichens occupying the place of woody fibre, 
 which is absent, we must regard it as certain, that the 
 soluble organic salts are destined to fulfil equally impor- 
 tant, though different functions, so much so, that we 
 could not conceive the complete development of a 
 plant without their presence, that is, without the pres- 
 ence of their acids, and consequently of their bases. 
 
 From these considerations we must perceive that ex- 
 act and trustworthy examinations of the ashes of plants 
 of the same kind growing upon different soils would be 
 of the greatest importance to vegetable physiology, and 
 would decide whether the facts above mentioned are the 
 results of an unchanging law for each family of plants, 
 and whether an invariable number can be found to ex- 
 press the quantity of oxygen which each species of plant 
 contains in the bases united with organic acids. In all 
 
154 OP THE INORGANIC 
 
 probability, such inquiries will lead to most important 
 results ; for it is clear, that if the production of a certain 
 unchanging quantity of an organic acid is required by 
 the peculiar nature of the organs of a plant, and is neces- 
 sary to its existence, then potash or lime must be taken 
 up by it, in order to form salts with this acid ; that if 
 these do not exist in sufficient quantity in the soil, other 
 bases must supply their place ; and that the progress of 
 a plant must be wholly arrested when none are present. 
 
 Seeds of the Salsola Kali, when sown in common 
 garden soil, produce a plant containing both potash and 
 soda ; while the plants grown from the seeds of this con- 
 tain only salts of potash, with mere traces of muriate of 
 soda. (Cadet.) 
 
 The existence of vegetable alkalies in combination 
 with organic acids gives great weight to the opinion, 
 that alkaline bases in general are connected with the de- 
 velopment of plants. 
 
 If potatoes are grown where they are not supplied 
 with earth, the magazine of inorganic bases, (in cellars 
 for example,) a true alkali, called Solanin, of very poi- 
 sonous nature, is formed in the sprouts which extend 
 towards the light, while not the smallest trace of such a 
 substance can be discovered in the roots, herbs, blos- 
 soms, or fruits of potatoes grown in fields. (Otto).* 
 
 * The analysis of potatoes afforded M. Henry 
 
 Starch 13.3 
 
 Water 73.12 
 
 Albumen 0.92 
 
 Uncrystallizable sugar ..... 3.30 
 
 Volatile poisonous matter .... 0.05 
 
 Peculiar fatty matter 1.12 
 
 Parenchyma 6.79 
 
 Malic acid and salts 1.40 
 
 100.00 
 
CONSTITUENTS OF PLANTS. 155 
 
 In all the species of the Cinchona, kinic acid is found ; 
 but the quantity of quinina, cinchonina, and lime which 
 they contain is most variable. From the fixed bases in 
 the products of incineration, however, we may estimate 
 pretty accurately the quantity of the peculiar organic 
 bases. A maximum of the first corresponds to a mini- 
 mum of the latter as must necessarily be the case if they 
 mutually replace one another according to their equiva- 
 lents. We know that different kinds of opium contain 
 meconic acid, in combination with very difierent quan- 
 tities of narcotina, morphia, codeia, &c., the quantity 
 of one of these alkaloids diminishing on the increase of 
 the others. " Thus, the smallest quantity of morphia 
 is accompanied by a maximum of narcotina. Not a 
 trace of meconic acid* can be discovered in many kinds 
 of opium, but there is not on this account an absence of 
 acid, for the meconic is here replaced by sulphuric acid. 
 Here, also, we have an example of what has been before 
 stated, for in those kinds of opium where both these 
 acids exist, they are always found to bear a certain rela- 
 tive proportion to one another. 
 
 But if it be found, as appears to be the case in the 
 juice of poppies, that an organic acid may be replaced 
 by an inorganic, without impeding the growth of a plant, 
 we must admit the probability of this substitution taking 
 place in a much higher degree in the case of the inor- 
 ganic bases. 
 
 When roots find their more appropriate base in suffi- 
 cient quantity, they will take up less of another. 
 
 * Robiquet did not obtain a trace of meconate of lime from 300 lbs. 
 of opium, whilst in other kinds the quanlit}' was very considerable. 
 Ann. de Chim. liii. p. 4'-i5. — L. 
 
156 OP THE INORGANIC 
 
 These phenomena do not show themselves so fre- 
 quently in cultivated plants, because they are subjected 
 to special external conditions for the purpose of the pro- 
 duction of particular constituents or particular organs. 
 
 When the soil, in which a wiiite hyacinth is growing 
 in the state of blossom, is sprinkled with the juice of the 
 Phytolaca decandra,* the white blossoms assume, in one 
 or two hours, a red color, which again disappears after 
 a few days under the influence of sunshine, and they be- 
 come white and colorless as before f. The juice in 
 this case evidently enters into all parts of the plant, 
 without being at all changed in its chemical nature, or 
 without its presence being apparently either necessary or 
 injurious. But this condition is not permanent, and 
 when the blossoms have become again colorless, none 
 of the coloring matter remains ; and if it should occur, 
 that any of its elenients were adapted for the purposes 
 of nutrition of the j)lant, then these alone would be re- 
 tained, whilst the rest would be excreted in an altered 
 form by the roots. 
 
 Exactly the same thing must happen when we sprin- 
 kle a plant with a solution of chloride of potassium, 
 nitre, or nitrate of strontia ; they will enter into the dif- 
 ferent parts of the plant, just as the colored juice men- 
 tioned above, and will be found in its ashes if it should 
 be burnt at this period. Their presence is merely ac- 
 cidental ; but no conclusion can be hence deduced 
 against the necessity of the presence of other bases in 
 plants. The experiments of Macaire-Princep have 
 
 * American nightshade. 
 
 t Biot, in the Comptes rendus des Seances dc VAcadhnie des Sci- 
 ences, a Paris, ler Semestre, 1837. p. 12. 
 
CONSTITUENTS OF PLANTS. 157 
 
 shown that plants made to vegetate with their roots in a 
 weak sohjtion of acetate of lead (sugar of lead), and 
 then in rain-water, yield to the latter all the salt of lead 
 which they had previously absorbed. They return, 
 therefore, to the soil all matters which are unnecessary 
 to their existence. Again, when a plant, freely exposed 
 to the atmosphere, rain, and sunshine, is sprinkled with 
 a solution of nitrate of strontian, the salt is absorbed, 
 but it is again separated by the roots and removed fur- 
 ther from them by every shower of rain, which moistens 
 the soil, so that at last not a trace of it is to,be found in 
 the plant. 
 
 Let us consider the composition of the ashes of two 
 fir-trees as analyzed by an acute and most accurate 
 chemist. One of these grew in Norway on a soil, the 
 constituents of which never changed, but to which solu- 
 ble salts, and particularly common salt, were conveyed 
 in great quantity by rain-water. How did it happen 
 that its ashes contained no appreciable trace of salt, 
 although we are certain that its roots must have absorb- 
 ed it after every shower '' 
 
 We can explain the absence of salt in this case by 
 means of the direct and positive observations referred 
 to, which have shown that plants have the power of re- 
 turning to the soil all substances unnecessary to their 
 existence ; and the conclusion to which all the fore- 
 going facts lead us, when their real value and bearing 
 are apprehended, is that the alkaline bases existing in 
 the ashes of plants must be necessary to their growth, 
 since if this were not the case they would not be re- 
 tained. 
 
 The perfect development of a plant according to 
 this view is dependent on the presence of alkalies or 
 14 
 
158 OF THE INORGANIC 
 
 alkaline earths ; for when these substances are totally 
 wanting, its growth will be arrested, and when they are 
 only deficient, it must be impeded. 
 
 In order to apply these remarks, let us compare two 
 kinds of tree, the wood of which contains unequal 
 quantities of alkaline bases, and we shall find that one of 
 these grows luxuriantly in several soils, upon which the 
 others are scarcely able to vegetate. For example, 
 10,000 parts of oak wood yield 250 parts of ashes, the 
 same quantity of fir-wood only 83, of linden -wood 500, 
 of rye 440, and of the herb of the potato-plant 1500 
 parts.* 
 
 Firs and pines find a sufficient quantity of alkalies in 
 granitic and barren sandy soils, in which oaks will not 
 grow ; and wheat thrives in soils favorable for the 
 linden-tree, because the bases, which are necessary to 
 bring it to complete maturity, exist there in sufficient 
 quantity. The accuracy of these conclusions, so highly 
 important to agriculture and to the cultivation of forests, 
 can be proved by the most evident facts. 
 
 All kinds of grasses, the Erjuisetacece, for example, 
 contain in the outer parts of their leaves and stalk a 
 large quantity of silicic acid and potash, in the form of 
 acid silicate of potash. The proportion of this salt 
 does not vary perceptibly in the soil of corn-fields, be- 
 cause it is again conveyed to them as manure in the 
 form of putrefying straw. But this is not the case in a 
 meadow, and hence we never find a luxuriant crop of 
 grass f on sandy and calcareous soils which contain 
 
 * Berthier, Annales de Chiviie et de Physique, tome xxx. p. 248. 
 
 t It would be of importance to examine what alkalies are contained 
 in the ashes of the sea-shore plants whicii grow in the humid hollows 
 of downs, and especially in those of the millet-grass. {Hartig.) If 
 
CONSTITUENTS OF PLANTS. 159 
 
 liltle potash, evidently because one of the constituents 
 indispensable to the growth of the plants is wanting. 
 Soils formed from basalt, grauwacke, and porphyry are, 
 cceteris paribus, the best for meadow land, on account 
 of the quantity of potash which enters into their compo- 
 sition. The potash abstracted by the plants is restored 
 during the annual irrigation.* That contained in the 
 soil itself is inexhaustible in comparison w^ith the quan- 
 tity removed by plants. 
 
 But when we increase the crop of grass in a meadow 
 by means of gypsum, we remove a greater quantity of 
 potash with the hay than can, under the same circum- 
 stances, be restored. Hence it happens, that after the 
 lapse of several years, the crops of grass on the mead- 
 ows manured with gypsum diminish, owing to the defi- 
 ciency of potash. But if the meadow be strewed from 
 time to time with wood-ashes, even w'ith the lixiviated 
 ashes which have been used by soap-boilers, (in Ger- 
 many much soap is made from the ashes of wood,) then 
 the grass thrives as luxuriantly as before. The ashes 
 are only a means of restoring the potash. f 
 
 potash is not found in them it must certainly be replaced bj soda as 
 in the salsola, or by lime as in the Plumhaginea. — L. 
 
 * A very high value is attached in Germany to the cultivation of 
 orrass as winter provision for cattle, and the greatest care is used in 
 order to obtain the greatest possible quantity. In the vicinity of 
 Liegen (a town in Nassau), from three to five perfect crops are ob- 
 tained from one meadow, and this is effected by covering the fields 
 with river-water, which is conducted over the meadow in spring by 
 numerous small canals. This is found to be of such advantage, that 
 supposing a meadow not so treated to yield 1,000 lbs. of hay, then 
 from one thus watered 4,500 lbs. are produced. In respect to the 
 cultivation of meadows, the country around Liegen is considered to 
 be the best in all Germany. — L. 
 
 t The compost which has been employed with most advantage as 
 
160 OF THE INORGANIC 
 
 A harvest of grain is obtained every thirty or forty 
 years from the soil of the Ltineburg heath, by strewing 
 it with the ashes of the heath-plants (Erica vulgaris) 
 which grow on it. These plants during the long period 
 just mentioned collect the potash and soda, which are 
 conveyed to them by rain-water ; and it is by means of 
 these alkalies, that oats, barley, and rye, to which they 
 are indispensable, are enabled to grow on this sandy 
 heath. 
 
 The woodcutters in the vicinity of Heidelberg have 
 the privilege of cultivating the soil for their own use, 
 after felling the trees used for making tan. Before sow- 
 ing the land thus obtained, the branches, roots, and 
 leaves are in every case burned, and the ashes used as 
 a manure, which is found to be quite indispensable for 
 the growth of the grain. The soil itself, upon which 
 the oats grow in this district, consists of sandstone ; and 
 although the trees find in it a quantity of alkaline earths 
 sufficient for their own sustenance, yet in its ordinary 
 condition it is incapable of producing grain. 
 
 a top dressing to grass by Mr., Haggerston, on the estate of J. P. 
 Gushing, Esq., at Watertown, is prepared from peat and barilla alone. 
 
 The peat previously cut and dried is made into heaps with alter- 
 nate layers of barilla, the thickness of each layer of peat being 
 eight inches, and of the barilla four inches. This heap is allowed to 
 remain undisturbed during the winter, in the spring it is carefully 
 turned and then allowed to remain until the ensuing autumn, when 
 it is spread upon the land. 
 
 Peat which is to be ploughed into the land, having been deposited 
 in the yard to whicii swine have free access, is mixed with stable 
 manure in the proportion of two thirds peat to one third manure. 
 
 Barilla is the crude soda which is imported from Spain, Sicily, &c., 
 where it is prepared by burning the plant called salsola soda. Ac- 
 cording to Dr. Ure it contains iJO per cent, of real alkali (soda) with 
 muriates and sulphates of soda, some lime and alumina, with very 
 little sulphur. 
 
CONSTITUENTS OF PLANTS. 161 
 
 The most decisive proof of the use of strong manure 
 was obtained at Bingen (a town on the Rhine), where 
 the produce and development of vines were highly in- 
 creased by manuring them with such substances as 
 shavings of horn, &c., but after some years the forma- 
 tion of the wood and leaves decreased to the great loss 
 of the possessor, to such a degree, that he has long had 
 cause to regret his departure from the usual methods. 
 By the manure employed by him, the vines had been 
 too much hastened in their growth ; in two or three 
 years they had exhausted the potash in the formation of 
 their fruit, leaves, and wood, so that none remained for 
 the future crops, his manure not having contained any 
 potash. 
 
 There are vineyards on the Rhine, the plants of 
 which are above a hundred years old, and all of these 
 have been cultivated by manuring them with cow-dung, 
 a manure containing a large proportion of potash, al- 
 though very little nitrogen. All the potash, in fact, 
 which is contained in the food consumed by a cow is 
 again immediately discharged in its excrements. 
 
 The experience of a proprietor of land in the vicinity 
 of Gottingen offers a most remarkable example of the 
 incapability of a soil to produce wheat or grasses in gen- 
 eral, when it fails in any one of the materials necessary 
 to their growth. In order to obtain potash, he planted 
 his whole land with wormwood, the ashes of which are 
 well known to contain a large proportion of the carbo- 
 nate of that alkali. The consequence was, that he ren- 
 dered his land quite incapable of bearing grain for many 
 years, in consequence of having entirely deprived the 
 soil of its potash. 
 
 The leaves and small branches of trees contain the 
 14* 
 
162 OF THE INORGANIC 
 
 most potash ; and the quantity of them which is annually- 
 taken from a wood, for tiie purpose of being employed 
 as litter,* contain more of that alkali than all the old 
 wood which is cut down. The bark and foilage of 
 oaks, for example, contain from 6 to 9 per cent, of this 
 alkali ; the needles of firs and pines 8 per cent. 
 
 With every 2,650 lbs. of fir-wood, which are yearly 
 removed from an acre of forest, only from 0.114 to 
 0.53 lbs. of alkalies are abstracted from the soil, calcu- 
 lating the ashes at 0.S3 per cent. The moss, however, 
 which covers the ground, and of which the ashes are 
 known to contain so much alkali, continues uninterrupt- 
 ed in its growth, and retains that potash on the surface, 
 which would otherwise so easily penetrate with the rain 
 through the sandy soil. By its decay, an abundant 
 provision of alkalies is supplied to the roots of the trees, 
 and a fresh supply is rendered unnecessary. 
 
 The supposition of alkalies, metallic oxides, or inor- 
 ganic matter in general, being produced by plants, is en- 
 tirely refuted by these well authenticated facts. 
 
 It is thought very remarkable, that those plants of the 
 grass tribe, the seeds of which furnish food for man, fol- 
 low him like the domestic animals. But saline plants 
 seek the sea-shore or saline springs, and the Chenopo- 
 dium the dunghill from similar causes. Saline plants 
 require common salt, and the plants which grow only on 
 
 * [This refers to a custom some time since very prevalent in Ger- 
 many, although now discontinued. The leaves and small twigs of 
 trees were gleaned from the forests by poor people, for the purpose of 
 beintr used as litter for their cattle. The trees, however, were found to 
 suffer so much in consequence, that a strict prohibition is now placed 
 acrainst their removal. The cause of the injury was that stated in the 
 text. — Trans.] 
 
CONSTITUENTS OF PLANTS. 163 
 
 dunghills, need ammonia and nitrates, and they are at- 
 tracted whither these can be found, just as the dung-fly 
 is to animal excrements. So likewise none of our corn 
 plants can bear perfect seeds, that is, seeds yielding 
 flour, without a large supply of phosphate of magnesia 
 and ammonia, substances which they require for their 
 maturity. And hence, these plants grow only in a soil 
 where these three constituents are found combined, and 
 no soil is richer in them, than those where men and ani- 
 mals dwell together ; where the urine and excrements 
 of these are found corn plants appear, because their 
 seeds cannot attain maturity unless supplied with the 
 constituents of those matters. 
 
 When we find sea plants near our salt works, several 
 hundred miles, distant from the sea, we know that their 
 seeds have been carried there in a very natural manner, 
 namely, by wind or birds, which have spread them over 
 the whole surface of the earth, although they grow only 
 in those places in which they find the conditions essen- 
 tial to their life. 
 
 Numerous small fish, of not more than two inches in 
 length (^G asterosteus aculeatus), are found in the salt- 
 pans of the graduating house at Nidda (a village in 
 Hesse Darmstadt). No living animal is found in the 
 salt-pans of Neuheim, situated about 18 miles from Nid- 
 da ; but the water there contains so much carbonic acid 
 and lime, that the walls of the graduating house are cov- 
 ered with stalactites. Hence the eggs conveyed to this 
 place by birds do not find the conditions necessary for 
 their development, which they found in the former 
 place.* 
 
 * " The itch insect (Icarus Scabiei) is considered by Burdach as the 
 
164 OF THE INORGANIC 
 
 How much more wonderful and inexplicable does it 
 appear, that bodies which remain fixed in the strong heat 
 of a fire, have under certain conditions the property of 
 volatilizing, and, at ordinary temperatures, of passing 
 into a state, of which we cannot say whether they have 
 really assumed the form of a gas or are dissolved in 
 one ! Steam or vapors in general have a very singular 
 influence in causing the volatilization of these bodies, 
 that is, of causing them to assume the gaseous form. A 
 liquid during evaporation communicates the power of as- 
 suming the same state in a greater or less degree to all 
 substances dissolved in it, although they do not of them- 
 selves possess that property. 
 
 Boracic acid * is a substance which is completely fixed 
 in the fire ; it suffers no change of weight appreciable 
 by the most delicate balance, when exposed to a white 
 heat, and, therefore, it is not volatile. Yet its solution 
 in water cannot be evaporated by the gentlest heat, with- 
 
 production of a morbid condition, so likewise lice in children; the 
 original generation of the fresh water muscle (mytilus) in fish ponds, 
 of sea plants in the vicinity of salt works, of nettles and grasses, of 
 fish in pools of rain, of trout in mountain streams, &c., is according 
 to the same natural philosopher not impossible." A soil consisting of 
 crumbled rocks, decayed vegetables, rain and salt water, &c., is here 
 supposed to possess the power of generating shell fish, trout, and salt- 
 worts (saUcornia). All inquiry is arrested by such opinions, when 
 propagated by a teacher who enjoys a merited reputation, obtained by 
 knowledge and hard labor. These subjects, however, have hitherto 
 met with the most superficial observation, although they well merit 
 strict investigation. The dark, the secret, the mysterious, the enigr 
 malic, is, in fact, too seducing for the youthful and philosophic mind, 
 which would penetrate the deepest depths of nature, without the as- 
 sistance of the shaft or ladder of the miner. This is poetry, but not 
 sober philosophical inquiry. — L. 
 * The acid from borax. 
 
CONSTITUENTS OF PLANTS. 165 
 
 out the escape of a sensible quantity of the acid with 
 the steam. Hence it is that a loss is always experi- 
 enced in the analysis of minerals containing this acid, 
 when liquids in which it is dissolved are evaporated. 
 The quantity of boracic acid which escapes with a cubic 
 foot of steam, at the temperature of boiling water, can- 
 not be detected by our most sensible reagents ; and 
 nevertheless the many hundred tons annually brought 
 from Italy as an article of commerce, are procured by 
 the uninterrupted accumulation of this apparently inap- 
 preciable quantity. The hot steam which issues from 
 the interior of the earth is allowed to pass through cold 
 water in the lagoons of Castel Nuovo and Cherchiago ; 
 in this way is the boracic acid gradually accumulated, till 
 at last it may be obtained in crystals by the evaporation 
 of the water. It is evident, from the temperature of the 
 steam, that it must have come out of depths in which 
 human beings and animals never could have lived, and 
 yet it is very remarkable and highly important that am- 
 monia is never absent from it. In the large works in 
 Liverpool, where natural boracic acid is converted into 
 borax, many hundred pounds of sulphate of ammonia 
 are obtained at the same time. 
 
 This ammonia has not been produced by the animal 
 organism, it existed before the creation of human beings; 
 it is a part^ a primary constituent, of the globe itself. 
 
 The experiments instituted under .Lavoisier^s guid- 
 ance by the Direction des poudres et salpetres, have 
 proved that during the evaporation of the saltpetre ley, 
 the salt volatilizes with the water, and causes a loss 
 which could not before be explained. It is known also, 
 that, in sea storms, leaves of plants in the direction of 
 the wind are covered with crystals of salt, even at the 
 
166 OF THE INOftGANlC 
 
 distance of from 20 to 30 miles from the sea. But it 
 does not require a storm to cause the volatilization of the 
 salt, for the air hanging over the sea always contains 
 enough of this substance to make a solution of nitrate of 
 silver turbid, and every breeze must carry this away. 
 Now, as thousands of tons of sea-water annually evapo- 
 rate into the atmosphere, a corresponding quantity of the 
 salts dissolved in it, viz. of common salt, chloride of 
 potassium, magnesia, and the remaining constituents of 
 the sea-water will be conveyed by wind to the land. 
 
 This volatilization is a source of considerable loss in 
 salt-works, especially where the proportion of salt in the 
 water is not large. This has been completely proved 
 at the salt-works of Nauheim, by the very intelligent 
 director of that establishment, JM. Wilhelmi. He hung 
 a plate of glass between two evaporating houses, which 
 were about 1200 paces distant from each other, and 
 found in the morning, after the drying of the dew, that 
 the glass was covered with crystals of salt on one or the 
 other side, according to the direction of the wind. 
 
 By the continual evaporation of the sea, its salts * are 
 spread over the whole surface of the earth ; and being 
 subsequently carried down by the rain, furnish to the 
 vegetation those salts necessary to its existence. This 
 is the origin of the salts found in the ashes of plants, 
 in those cases where the soil could not have yielded 
 them. 
 
 * According to Marcet, sea- water contains in 1000 parts, 
 2G.6GC Chloride of Sodium. 
 4.CC0 Sulpliate of Soda. 
 1.232 Ciiloride of Potassium. 
 5.152 Chloride of Magnesium. 
 1.5 Sulphate of Lime. 
 
CONSTITUENTS OF PLANTS. 167 
 
 In a comprehensive view of the phenomena of nature, 
 we have no scale for that w^hich we are accustomed to 
 name, small or great ; all our ideas are proportioned to 
 what we see around us, but how insignificant are they in 
 comparison with the whole mass of the globe ! that 
 which is scarcely observable in a confined district ap- 
 pears inconceivably large when regarded in its extension 
 through unlimited space. The- atmosphere contains only 
 a thousandth part of its weight of carbonic acid ; and 
 yet small as this proportion appears, it is quite sufficient 
 to supply the whole of the present generation of living 
 beings with carbon for a thousand years, even if it were 
 not renewed. Sea-water contains -j-23^0 o ^^ '^s weight 
 of carbonate of lime ; and this quantity, although scarcely 
 appreciable in a pound, is the source from which myriads 
 of marine mollusca and corals are supplied with materials 
 for their habitations. 
 
 Whilst the air contains only from 4 to 6 ten-thousandth 
 parts of its volume of carbonic acid, sea-water contains 
 100 times more (10,000 volumes of sea-water contain 
 620 volumes of carbonic acid, — Laurent, Bouillon, 
 Lagrange). Ammonia* is also found in this water, 
 so that the same conditions which sustain living beings 
 on the land are combined in this medium, in which a 
 whole world of other plants and animals exist. 
 
 The roots of plants are constantly engaged in collect- 
 ing from the rain those alkalies which formed part of the 
 sea-vvaier, and also those of the water of springs, which 
 penetrates the soil. Without alkalies and alkaline bases 
 
 * When the solid saline residue obtained by the evaporation of sea- 
 water is heated in a retort to redness, a sublimate of sal-ammoniac is 
 obtained. — Marcet. 
 
168 OF THE INORGANIC CONSTITUENTS OF PLANTS. 
 
 most plants could not exist, and without plants the alka- 
 lies would disappear gradually from the surface of the 
 earth , 
 
 When it is considered, that sea-water contains less 
 than one-millionth of its own weight of iodine,* and that 
 all combinations of iodine with the metallic bases of 
 alkalies are highly soluble in water, some provision must 
 necessarily be supposed to exist in the organization of 
 sea-weed and the different kinds of Fuci, by which they 
 are enabled during their life to extract iodine in the form 
 of a soluble salt from sea-water, and to assimilate it in 
 such a manner, that it is not again restored to the sur- 
 rounding medium. These plants are collectors of iodine, 
 just as land-plants are of alkalies ; and they yield us this 
 element, in quantities such as we could not otherwise 
 obtain from the water without the evaporation of whole 
 seas. 
 
 We take it for granted, that the sea plants require 
 metallic iodides for their growth, and that their existence 
 is dependent on the presence of those substances. With 
 equal justice, then, we conclude, that the alkalies and 
 alkaline earths, always found in the ashes of land-plants, 
 are likewise necessary for their development. 
 
 * This substance was discovered in 1812, and is obtained from 
 marine plants ; it is found also in sea-water and several mineral 
 springs in combination with hydrogen as hydriodic acid. With bases 
 this acid forms hydriodates. Iodine has not been decomposed. It is 
 a solid and at about 350" F. passes into vapor of a beautiful violet 
 color; hence its name. 
 
THE ART OF CULTURE. 169 
 
 CHAPTER VII. 
 
 THE ART OF CULTURE. 
 
 The conditions necessary for the life of all vegetables 
 have been considered in the preceding part of the work. 
 Carbonic acid, ammonia, and water yield elements for 
 all the organs of plants. Certain inorganic substances, — 
 salts and metallic oxides, — serve peculiar functions in 
 their organism, and many of them must be viewed as 
 essential constituents of particular parts. 
 
 The atmosphere and the soil offer the same kind of 
 nourishment to the leaves and roots. The former con- 
 tains a comparatively inexhaustible supply of carbonic 
 acid and ammomia ; the latter, by means of its humus, 
 generates constantly fresh carbonic acid, whilst, during 
 the winter, rain and snow introduce into the soil a 
 quantity of ammonia, sufficient for the development of 
 the leaves and blossoms. 
 
 The complete, or it may be said, the absolute insol- 
 ubility in cold water of vegetable matter in progress of 
 decay, (humus,) appears on closer consideration to be 
 a most wise arrangement of nature. For if humus pos- 
 sessed even a smaller degree of solubility, than that 
 ascribed to the substance called humic acid, it must be 
 dissolved by rain-water. Thus, the yearly irrigation of 
 meadows (see note at page 159), which lasts for several 
 weeks, would remove a great part of it from the ground, 
 and a heavy and continued rain would impoverish a soil. 
 But it is soluble only wiien combined with oxygen -, 
 it can be taken up by water, therefore, only as carbonic 
 acid. 
 
 15 
 
170 THE ART OF CULTURE. 
 
 When kept in a dry place, humus may be preserved 
 for centuries, but when moistened with water, it converts 
 the surrounding oxygen into carbonic acid. As soon as 
 the action of the air ceases, that is, as soon as it is de- 
 prived of oxygen, the humus suffers no further change. 
 Its decay proceeds only when plants grow in the soil 
 containing it ; for they absorb by their roots the carbonic 
 acid as it is formed. Their soil receives again from liv- 
 ing plants the carbonaceous matter it thus loses, so that 
 the proportion of humus in it does not decrease. 
 
 The stalactitic caverns in Franconia, and those in the 
 vicinity of Baireuth, and Streitberg, lie beneath a fertile 
 arable soil ; the abundant decaying vegetables or humus 
 in this soil, being acted on by moisture and air, constant- 
 ly evolve carbonic acid, which is dissolved by the rain. 
 The rain-water thus impregnated permeates the porous 
 limestone, which forms the walls and roofs of the cav- 
 erns, and dissolves in its passage as much carbonate of 
 lime as corresponds to the quantity of carbonic acid con- 
 tained in it. Water and the excess of carbonic acid 
 evaporate from this solution when it has reached the in- 
 terior of the caverns, and the limestone is deposited on ■ 
 the walls and roofs in crystalline crusts of various forms- 
 There are few spots on the earth where so many circum- 
 stances favorable to the production of humate of lime 
 are combined, if the humus actually existed in the soil in 
 the form of humic acid. Decaying vegetable matter, 
 water, and lime in solution, are brought together, but 
 the stalactites formed contain no trace of vegetable mat- 
 ter, and no humic acid ; they are of glistening white or 
 yellowish color, and in part transparent, like calcareous 
 spar, and may be heated to redness without becoming 
 black. 
 
USE OF THE HUMUS, 171 
 
 The subterranean vaults in the old castles near the 
 Rhine, the " Bergstrasse " and Wetherau, are con- 
 structed of sandstone, granite, or basalt, and present ap- 
 pearances similar to the limestone caverns. The roofs 
 of these vaults or cellars are covered externally to the 
 thickness of several feet with vegetable mould, which 
 has been formed by the decay of plants. The rain fall- 
 ing upon them sinks through the earth, and dissolves the 
 mortar by means of the carbonic acid derived from the 
 mould ; and this solution evaporating in the interior of 
 the vaults, covers them with small thin stalactites, which 
 are quite free from humic acid. 
 
 In such a filtering apparatus, built by the hand of 
 nature, we have placed before us experiments which have 
 been continued for a hundred or a thousand years. Now, 
 if water possesses the power of dissolving a hundred- 
 thousandth part of its own weight of humic acid or hu- 
 mate of lime, and humic acid were present, we should 
 find the inner surface of the roofs of these vaults and 
 caverns covered with these substances ; but we cannot 
 detect the smallest trace of them. There could scarcely 
 be found a more clear and convincing proof of the ab- 
 sence of the humic acid of chemists in common vegeta- 
 ble mould. 
 
 The common view, which has been adopted respect- 
 ing the modus operandi of humic acid, has given occasion 
 to the following inexplicable phenomenon: — A very 
 small quantity of humic acid dissolved in water gives it 
 a yellow or brown color. Hence it would be supposed, 
 that a soil would be more fruitful in proportion as it was 
 capable of giving this color to water, that is, of yielding 
 it humic acid. But it is very remarkable that plants do 
 not thrive in such a soil, and that all manure must have 
 lost this property before it can exercise a favorable in- 
 
172 THE ART OF CULTURE. 
 
 fluence upon their vegetation. Water from barren peat 
 soils and marshy meadows, upon which few plants flour- 
 ish, contains much of this humic acid ; but all agricul- 
 turists and gardeners agree that the most suitable and best 
 manure for plants is that which has completely lost the 
 property of giving a color to water.* 
 
 The soluble substance, which gives to water a brown 
 color, is a product of the putrefaction of all animal and 
 vegetable matters ; its formation is an evidence, that 
 there is not oxygen sufficient to begin or at least to com- 
 plete the decay. The brown solutions, containing this 
 substance, are decolorized in the air, by absorbing oxy- 
 gen, and a black coaly matter precipitates, — the sub- 
 stance named "coal of humus." Now if a soil were 
 impregnated with this matter, the effect on the roots of 
 plants would be the same as that of entirely depriving the 
 soil of oxygen ; plants would as little be able to grow in 
 such ground, as they would if hydrated protoxide of '.oA 
 were mixed with the soil. All plants die in soils and 
 water which contain no oxygen ; absence of air acts ex- 
 actly in the same manner as an excess of carbonic acid. 
 Stagnant water on a marshy soil excludes air, but a re- 
 newal of water has the same effect as a renewal of air, 
 because water contains it in solution. If the water is 
 withdrawn from a marsh, free access is given to the air, 
 and the marsh is changed into a fruitful meadow. 
 
 In a soil to which the air has no access, or at most 
 but very little, the remains of animals and vegetables do 
 not decay, for they can only do so when freely supplied 
 with oxygen ; but they undergo putrefaction, for which 
 air is present in sufficient quantity. Putrefaction is 
 known to be a most powerful deoxidizing process, the 
 
 * See Appendix. 
 
USE OF THE HUMUS. 173 
 
 influence of which extends to all surrounding bodies, 
 even to the roots and the plants themselves. All sub- 
 stances from which oxygen can be extracted yield it to 
 putrefying bodies ; yellow oxide of iron passes into the 
 state of black oxide, sulphate of iron into sulphuret of 
 iron, &c. 
 
 The frequent renewal of air by ploughing, and the 
 preparation of the soil, especially its contact with alka- 
 line metallic oxides, the ashes of brown coal, burnt lime 
 or limestone, change the putrefaction of its organic con- 
 stituents into a pure process of oxidation ; and from the 
 moment at which all the organic matter existing in a soil 
 enters into a state of oxidation or decay, its fertility is 
 increased. The oxygen is no longer employed for the 
 conversion of the brown soluble matter into the insoluble 
 coal of humus, but serves for the formation of carbonic 
 acid. This change takes place very slowly, and, in some 
 instances, the oxygen is completely excluded by it. And, 
 whenever this happens, the soil loses its fertility. Thus, 
 in the vicinity of Salzhausen (a village in Hesse Darm- 
 stadt, famed for its mineral springs), upon a meadow 
 called Griinschwalheimer, unfruitful spots are seen here 
 and there covered with a yellow grass. If a hole be 
 bored from 20 to 25 feet deep in one of these spots, 
 carbonic acid is emitted from it with such violence, that 
 the noise made by the escape of the gas may be distinctly 
 heard at the distance of several feet. Here the carbonic 
 acid rising to the surface displaces completely all the air, 
 and consequently all the oxygen, from the soil ; and without 
 oxygen, neither seeds nor roots can be developed ; a 
 plant will not vegetate in pure nitrogen or carbonic acid 
 gas.* 
 
 * See note pao-e 119. 
 
 15* 
 
174 THE ART OF CULTURE. 
 
 Humus supplies young plants with nourishment by the 
 roots, until their leaves are matured sufficiently to act as 
 exterior organs of nutrition ; its quantity heightens the 
 fertility of a soil by yielding more nourishment in this 
 first period of growth, and consequently by increasing 
 the number of organs of atmospheric nutrition. Those 
 plants, which receive their first food from the substance 
 of their seeds, such as bulbous plants, could completely 
 dispense with humus ; its presence is useful only in so 
 far as it increases and accelerates their development, but 
 it is not necessary, — indeed, an excess of it at the com- 
 mencement of their growth is, in a certain measure, in- 
 jurious. 
 
 The amount of food which young plants can take from 
 the atmosphere in the form of carbonic acid and ammonia 
 is limited ; they cannot assimilate more than the air con- 
 tains. Now, if the quantity of their stems, leaves, and 
 branches has been increased by the excess of food yield- 
 ed by the soil at the commencement of their develop- 
 ment, they will require for the completion of their growth, 
 and for the formation of their blossoms and fruits, more 
 nourishment from the air than it can aflx)rd, and conse- 
 quently they will not reach maturity. In many cases the 
 nourishment afforded by the air under these circumstan- 
 ces suffices only to complete the formation of the leaves, 
 stems, and branches. The same result then ensues as 
 when ornamental plants are transplanted from the pots in 
 which they have grown to larger ones, in which their 
 roots are permitted to increase and multiply. All their 
 nourishment is employed for the increase of their roots 
 and leaves ; they spring, as it is said, into an herb or 
 weed, but do not blossom. When, on the contrary, we 
 take away part of the branches, and of course their 
 
NUTRITION AND GROWTH OF PLANTS. 175 
 
 leaves with them, from dwarf trees, since we thus pre- 
 vent the development of new branches, an excess of 
 nutriment is artificially procured for the trees, and is em- 
 ployed by them in the increase of the blossoms and en- 
 largement of the fruit. It is to effect this purpose that 
 vines are pruned. 
 
 A new and peculiar process of vegetation ensues in all 
 perennial plants, such as shrubs, fruit and forest trees, 
 after the complete maturity of their fruit. The stem of 
 annual plants, at this period of their growth, becomes 
 woody, and their leaves change in color. The leaves of 
 trees and shrubs on the contrary remain in activity until 
 the commencement of the winter. The formation of the 
 layers of wood progresses, the wood becomes harder and 
 more solid, but after August the leaves form no more 
 wood : all the carbonic acid which the plants now ab- 
 sorb is employed for the production of nutritive matter 
 for the following year : instead of woody fibre, starch is 
 formed, and is difllised through every part of the plant 
 by the autumnal sap (seve d'Aoiit)*. According to the 
 observations of M. Heyer, the starch thus deposited in 
 the body of the tree can be recognised in its known form 
 by the aid of a good microscope. The barks of several 
 aspens and pine trees f contain so much of this substance 
 
 * Hartig, in Erdmann and Schweigger-Seidels JoMr77a/, V. 217, 1835. 
 
 t It is well known that bread is made from the barks of pines in 
 Sweden duiing famines. 
 
 The following directions are given by Professor Aulenrielh for 
 preparing a palatable and nutritious bread from the beech and other 
 woods destitute of turpentine. Every thing soluble in water is first 
 removed by frequent maceration and boiling, the wood is then to be 
 reduced to a minute state of division, not merely into fine fibres, but 
 actual powder ; and after being repeatedly subjected to heat in an 
 oven, is ground in the usual manner of corn. Wood thus prepared, 
 
176 THE ART OF CULTURE. 
 
 that it can be extracted from them as from potatoes, by 
 trituration with water. It exists also in the roots and 
 other parts of perennial plants. A very early winter or 
 sudden change of temperature prevents the formation of 
 this provision for the following year ; the wood, as in 
 the case of the vine-stock, for example, does not ripen, 
 and its growth is in the next year very limited. 
 
 From the starch thus accumulated, sugar and gum 
 are produced in the succeeding spring, while from the 
 gum those constituents of the leaves and young sprouts 
 which contain no nitrogen, are in their turn formed. 
 After potatoes have germinated, the quantity of starch 
 in them is found diminished. The juice of the maple- 
 tree ceases to be sweet from the loss of sugar when its 
 buds, blossoms, and leaves attain their maturity. 
 
 The branch of a willow, which contains a large quan- 
 tity of granules of starch in every part of its woody sub- 
 stance, puts forth both roots and leaves in pure distilled 
 rain-water ; but in proportion as it grows, the starch 
 disappears, it being evidently exhausted for the forma- 
 tion of the roots and leaves. In the course of these 
 experiments, J\I. Heyer made the interesting observa- 
 tion, that such branches when placed in snow-water 
 (which contains ammonia) produced roots three or four 
 times longer than those which they formed in pure dis- 
 according to the author, acquires the smell and taste of corn flour. 
 It is, however, never quite white. It agrees with corn flour in not 
 fermenting without the addition of leaven, and in this case some 
 leaven of corn flour is found to answer best. With this it makes a 
 perfectly uniform and spongy bread ; and when it is thoroughly 
 baked, and has much crust, it has a much better taste of bread than 
 what in time of scarcity is prepared from the bran and husks of corn. 
 Wood-flour also, boiled in water, forms a thick, tough, trembling 
 jelly, which is very nutritious. — Philosophical Transactions, 1827, 
 
NUTRITION AND GROWTH OF PLANTS. 177 
 
 tilled water, and that this pure water remained clear, 
 while the rain-water gradually acquired a yellow color. 
 
 Upon the blossoming of the sugar-cane, likewise, 
 part of the sugar disappears : and it has been ascertain- 
 ed, that the sugar does not accumulate in the beet-root 
 until after the leaves are completely formed. 
 
 Much attention has recently been drawn to the fact 
 that the produce of potatoes may be much increased by- 
 plucking off the blossoms from the plants producing 
 them, a result quite consistent with theory. This im- 
 portant observation has been completely confirmed by 
 M. Zeller, the director of the Agricultural Society at 
 Darmstadt. In the year 1839 two fields of the same 
 size, lying side by side and manured in the same man- 
 ner, were planted with potatoes. When the plants had 
 flowered, the blossoms were removed from those in one 
 field, while those in the other field were left untouched. 
 The former produced 47 bolls, the latter only 37 bolls. 
 
 These well-authenticated observations remove every 
 doubt as to the part which sugar, starch, and gum play 
 in the development of plants ; and it ceases to be enig- 
 matical, why these three substances exercise no influ- 
 ence on the growth or process of nutrition of a matured 
 plant, when supplied to them as food. 
 
 The accumulation of starch in plants during the au- 
 tumn has been compared, although certainly errone- 
 ously, to the fattening of hibernating animals before 
 their winter sleep ; but in these animals every vital 
 function except the process of respiration is suspended, 
 and they only require, like a lamp slowly burning, a 
 substance rich in carbon and hydrogen to support the 
 process of combustion in the lungs. On their awaken- 
 ing from their torpor in the spring, the fat has disap- 
 
178 THE ART OF CULTURE. 
 
 peared, but has not served as nourishment. It has not 
 caused the least increase in any part of their body, 
 neither has it changed the quahty of any of their organs. 
 With nutrition, properly so called, the fat in these ani- 
 mals has not the least connexion. 
 
 The annual plants form and collect their future nour- 
 ishment in the same way as the perennial ; they store 
 it in their seeds in the form of vegetable albumen, 
 starch, and gum, which are used by the germs for the 
 formation of their leaves and first radical fibres. The 
 proper nutrition of the plants, their increase in size, 
 begins after these organs are formed. 
 
 Every germ and every bud of a perennial plant is 
 the engrafted embryo of a new individual, while the 
 nutriment accumulated in the stem and roots, corre- 
 sponds to the albumen of the seeds. 
 
 Nutritive matters are, correctly speaking, those sub- 
 stances which, when presented from without, are capa- 
 ble of sustaining the life and all the functions of an 
 organism, by furnishing to the different parts of plants 
 the materials for the production of their peculiar con- 
 stituents. 
 
 In animals, the blood is the source of the material of 
 the muscles and nerves ; by one of its component parts, 
 the blood supports the process of respiration, by others, 
 the peculiar vital functions ; every part of the body is 
 supplied with nourishment by it, but its own production 
 is a special function, without which we could not con- 
 ceive life to continue. If we destroy the activity of the 
 organs which produce it, or if we inject the blood of one 
 animal into the veins of another, at all events, if we 
 carry this beyond certain limits, death is the conse- 
 quence. 
 
NUTRITION AND GROWTH OF PLANTS. 179 
 
 If we could introduce into a tree woody fibre in state 
 of solution, it would be the sanfie thing as placing a po- 
 tato-plant to vegetate in a paste of starch. The office 
 of the leaves is to form starch, woody fibre, and sugar ; 
 consequently, if we convey these substances through 
 the roots, the vital functions of the leaves must cease, 
 and if the process of assimilation cannot take another 
 form, the plant must die. 
 
 Other substances must be present in a plant, besides 
 the starch, sugar, and gum, if these are to take part in 
 the development of the germ, leaves, and first radicle 
 fibres. There is no doubt that a grain of wheat con- 
 tains within itself the component parts of the germ and 
 of the radicle fibres, and we must suppose, exactly in 
 the proportion necessary for their formation. These 
 component parts are starch and gluten ; and it is evident 
 that neither of them alone, but that both simultaneously 
 assist in the formation of the root, for they both suffer 
 changes under the action of air, moisture, and a suitable 
 temperature. The starch is converted into sugar, and 
 the gluten also assumes a new form, and both acquire 
 the capability of being dissolved in water, and of thus 
 being conveyed to every part of the plant. Both the 
 starch and the gum are completely consumed in the 
 formation of the first part of the roots and leaves ; an 
 excess of either could not be used in the formation of 
 leaves, or in any other way. 
 
 The conversion of starch into sugar during the ger- 
 mination of grain is ascribed to a vegetable principle 
 called diastase, which is generated during the act of 
 commencing germination. But this mode of transfor- 
 mation can also be effected by gluten, although it re- 
 quires a longer time. Seeds which have germinated, 
 
180 THE ART OF CULTURE. 
 
 always contain much more diastase than is necessary for 
 the conversion of their starch into sugar, for five parts 
 by weight of starch can be converted into sugar by one 
 part of raahed barley. This excess of diastase can by 
 no means be regarded as accidental, for, like the starch, 
 it aids in the formation of the first organs of the young 
 plant, and disappears with the sugar ; diastase contains 
 nitrogen and furnishes the elements of vegetable albu- 
 men. 
 
 Carbonic acid, water, and ammonia are the food of 
 fully-developed plants ; starch, sugar, and gum serve, 
 when accompanied by an azotized substance, to sustain 
 the embryo, until its first organs of nutrition are unfold- 
 ed. The nutrition of a foetus and development of an 
 egg proceed in a totally different manner from that of 
 an animal which is separated from its parent ; the ex- 
 clusion of air does not endanger the life of the foetus, 
 but would certainly cause the death of the independent 
 animal. In the same manner, pure water is more ad- 
 vantageous to the growth of a young plant, than that 
 containing carbonic acid, but after a month the reverse 
 is the case. 
 
 The formation of sugar in maple-trees does not take 
 place in the roots, but in the woody substance of the 
 stem. The quantity of sugar in the sap augments until 
 it reaches a certain height in the stem of the plant, 
 above which point it remains stationary. 
 
 Just as germinating barley produces a substance 
 which, in contact with starch, causes it to lose its in- 
 solubility and to become sugar, so in the roots of the 
 maple, at the commencement of vegetation, a substance 
 must be formed, which, being dissolved in water, per- 
 meates the wood of the trunk, and converts into sugar 
 
NUTRITION AND GROWTH OF PLANTS. 181 
 
 the Starch, or whatever it may be, which it finds depos- 
 ited there. It is certain, that when a hole is bored into 
 the trunk of a maple-tree just above its roots, filled with 
 sugar, and then closed again, the sugar is dissolved by 
 the ascending sap. It is further possible, that this 
 sugar may be disposed of in the same manner as that 
 formed in the trunks ; at all events it is certam, that the 
 introduction of it does not prevent the action of the juice 
 upon the starch, and since the quantity of sugar pres- 
 ent is now greater than can be exhausted by the leaves 
 and buds, it is excreted from the surface of the leaves 
 or bark. Certain diseases of trees, for example, that 
 called honey-dew, evidently depend on the want of the 
 ^ue proportion between the quantity of the azotized and 
 that of unazotized substances which are supplied to them 
 as nutriment. 
 
 I^ whatever form, therefore, we supply plants with 
 those substances which are the products of their own ac- 
 tion, in no instance do they appear to have any efi^ect 
 .^ upon their growth, or to replace what they have lost. 
 Sugar, gum, and starch are not food for plants, and the 
 same must be said of humic acid, which is so closely 
 allied to them in composition. 
 
 If now we direct our attention to the particular organs 
 of a plant, we find every fibre and every particle of 
 wood surrounded by a juice containing an azotized mat- 
 ter : while the starch granules and sugar are enclosed in 
 cells formed of a substance containing nitrogen. Indeed 
 everywhere, in all the juices of the fruits and blossoms, 
 we find a substance, destitute of nitrogen, accompanied 
 by one which contains that element. 
 
 The wood of the stem cannot be formed, quasi wood, 
 in the leaves, but another substance must be produced, 
 16 
 
182 THE ART OF CULTURE. 
 
 which is capable of being transformed into wood. This 
 substance must be in a stale of solution, and accompa- 
 nied by a compound containing nitrogen ; it is very 
 probable, that the wood and the vegetable gluten, the 
 starch granules and the cells containing them, are formed 
 simultaneously, and in this case, a certain fixed propor- 
 tion between them would be a condition necessary for 
 their production. 
 
 According to this view, the assimilation of the sub- 
 stances generated in the leaves will (cfcteris paribus) 
 depend on the quantity of nitrogen contained in the 
 food. • When a sufficient quantity of nitrogen is not- 
 present to aid in the assimilation of the substances which 
 do not contain it, these substances will be separated as» 
 excrements from the bark, roots, leaves, and branches. 
 The exudations of mannite, gum, and sugar, in strong 
 and healthy plants, cannot be ascribed to any ^her 
 cause.* 
 
 Analogous phenomena are presented by the process 
 of digestion in the human organism. In order that the 
 loss which every part of the body sustains by the pro- 
 cesses of respiration and perspiration may be restored to 
 it, the organs of digestion require to be supplied with 
 food, consisting of substances containing nitrogen, and of 
 others destitute of it, in definite proportions. If the 
 substances which do not contain nitrogen preponderate, 
 either they will be expended in the formation of fat, or 
 
 * M. Trapp, in Giessen, possesses a Clerodendron fragrans, which 
 grows in the house, and exudes on the surface of its leaves in Sep- 
 tember large colorless drops of sugar-candy, which form regular crys- 
 tals upon drying; I am not aware whether the juice of this plant con- 
 tains sugar. — L. 
 
INFLUENCE OF THE FOOD ON THE PRODUCE. 183 
 
 they will pass unchanged through the organism. This 
 is particularly observed in those people who live almost 
 exclusively upon potatoes ; their excrements contain a 
 large quantity of unchanged granules of starch, of which 
 no trace can be detected when gluten, or flesh, is taken 
 in proper proportions, because, in this case, the starch 
 has been rendered capable of assimilation. Potatoes 
 which, when mixed with hay alone, are scarcely capa- 
 ble of supporting the strength of a horse, form with 
 bread and oats a strong and wholesome fodder. 
 
 It will be evident from the preceding considerations, 
 that the products generated by a plant may vary exceed- 
 ingly, according to the substances given it as food. A 
 superabundance of carbon in the state of carbonic acid 
 conveyed through the roots of plants, without being ac- 
 companied by nitrogen, cannot be converted either into 
 gluten, albumen, wood, 04* any other component part of an 
 .organ ; but either it will be separated in the form of ex- 
 crements, such as sugar, starch, oil, wax, resin, man- 
 nite, or gum, or these substances will be deposited in 
 greater or less quantity in the wide cells and vessels. 
 
 The quantity of gluten, vegetable albumen, and mu- 
 cilage, will augment when plants are supplied with an 
 excess of food containing nitrogen ; and ammoniacal 
 salts will remain in the sap, when, for example, in the 
 culture of the beet, we manure the soil with a highly ni- 
 trogenous substance, or when we suppress the functions 
 of the leaves, by removing them from the plant. 
 
 We know that the ananas (pine apple) is scarcely 
 eatable in its wild state, and that it shoots forth a great 
 quantity of leaves, when treated with rich animal ma- 
 nure, without the fruit on that account acquiring a large 
 amount of sugar ; that the quantity of starch in potatoes 
 
184 THE ART OF CULTURE. 
 
 increases, when the soil contains much humus, but de- 
 creases when the soil is manured with strong animal ma- 
 nure, although then the number of cells increases, the 
 potatoes acquiring in the first case a mealy, and in the 
 second, a soapy, consistence. Beet roots taken from a 
 barren sandy soil contain a maximum of sugar, and no 
 ammoniacal salts ; and the Teltowa turnip loses its 
 mealy state in a manured land, because there, all the 
 circumstances necessary for the formation of cells are 
 united. 
 
 An abnormal production of certain component parts 
 of plants presupposes a power and capability of assimi- 
 lation, to which the most powerful chemical action can- 
 not be compared. The best idea of it may be formed, 
 by considering that it surpasses in power the strongest 
 galvanic battery, with which we are not able to separate 
 the oxygen from carbonic acid. The affinity of chlorine 
 for hydrogen, and its power to decompose water under 
 the influence of liglu, and set at liberty its oxygen, 
 cannot be considered as at all equalling the power and 
 energy with which a leaf separated from a plant decom- 
 poses the carbonic acid which it absorbs. 
 
 The common opinion that only the direct solar rays 
 can effect the decomposition of carbonic acid in the 
 leaves of plants, and that reflected or diff"used light does 
 not possess this property, is wholly an error, for 'exactly 
 the same constituents are generated in a number of 
 plants, whether the direct rays of the sun fall upon them, 
 or whether they grow in the shade. They require light, 
 and, indeed, sun light, but it is not necessary that the 
 direct rays of the sun reach them. Their functions cer- 
 tainly proceed with greater intensity and rapidity in sun- 
 shine, than in the diffused light of day ; but there is 
 
INFLUENCE OF LIGHT. 185 
 
 nothing more in this than the similar action which light 
 exercises on ordinary chemical combinations, it merely 
 accelerates in a greater or less degree the action already 
 subsisting. 
 
 Chlorine and hydrogen combining form muriatic acid. 
 This combination is effected in a few hours in common 
 daylight, but it ensues instantly with a violent explosion, 
 under exposure to the direct solar rays, whilst not the 
 slightest change in the two gases takes place in perfect 
 darkness. When the liquid hydrocarburet of chlorine, 
 resulting from the union of the olefiant gas of the Dutch 
 chemists with chlorine, is exposed in a vessel with chlo- 
 rine gas to the direct solar rays, chloride of carbon is 
 immediately produced ; but the same compound can be 
 obtained with equal facility in the diffused light of day, 
 a longer time only being required. When this experi- 
 ment is performed in the way first mentioned, two pro- 
 ducts only are observed (muriatic acid and perchloride 
 of carbon) ; whilst by the latter method, a class of in- 
 termediate bodies are produced, in which the quantity of 
 chlorine constantly augments, until at last the whole li- 
 quid hydrocarburet of chlorine is converted into the 
 same two products as in the first case. Here, also, not 
 the slightest trace of decomposition takes place in the 
 dark. Nitric acid is decomposed in common daylight 
 into oxygen, and peroxide of nitrogen and chloride of 
 silver becomes black in the diffused llghi of day, as well 
 as in the direct solar rays ; — in short, all actions of a 
 similar kind proceed in the same way in diffused light as 
 well as in the solar light, the only difference consisting 
 in the time in which they are effected. It cannot be 
 otherwise in plants, for the mode of their nutriment is 
 the same in all, and their component substances afford 
 16* 
 
186 THE ART OF CULTURE. 
 
 proof, that their food has suffered absolutely the same 
 change, whether they grow in the sunshine or in the 
 shade. 
 
 All the carbonic acid, therefore, which we supply to 
 a plant will undergo a transformation, provided its quan- 
 tity be not greater than can be decomposed by the 
 leaves. We know that an excess of carbonic acid kills 
 plants, but we know also that nitrogen, to a certain 
 degree, is not essential for the decomposition of car- 
 bonic acid. All the experiments hitherto instituted, 
 prove that fresh leaves placed in water, impregnated 
 with carbonic acid, and exposed to the influence of solar 
 light, emit oxygen gas, whilst the carbonic acid disap- 
 pears. Now, in these experiments, no nitrogen is sup- 
 plied at the same time with the carbonic acid ; hence no 
 other conclusion can be drawn from them, than that ni- 
 trogen is not necessary for the decomposition of carbonic 
 acid, — for the exercise, therefore, of one of the func- 
 tions of plants. And yet the presence of a substance 
 containing this element appears to be indispensable for 
 the assimilation of the products newly formed by the 
 decomposition of the carbonic acid, and their consequent 
 adaptation for entering into the composition of the dif- 
 ferent organs. 
 
 . The carbon abstracted from the carbonic acid acquires 
 in the leaves a new form, in which it is soluble and 
 transferable to all parts of the phnt. In this new form 
 the carbon aids in constituting several new products ; 
 these are named sugar when they possess a sweet taste, 
 gum or mucilage when tasteless, and excrementitions 
 matters when expelled by the roots. 
 
 Hence it is evident, that the quantity and quality of 
 the substances generated by the vital processes of a plant 
 
INFLUENCE OF THE FOOD ON THE PRODUCE. 187 
 
 will vary according to the proportion of the different 
 kinds of food with which it is supplied. The develop- 
 ment of every part of a plant in a free and uncultivated 
 state depends on the amount and nature of the food 
 afforded to it, by the spot on which it grows. A plant 
 is developed on the most sterile and unfruitful soil, as 
 well as on the most luxuriant and fertile, the only differ- 
 ence which can be observed being in its height and size, 
 in the number of its twigs, branches, leaves, blossoms, 
 and fruit. Whilst the individual organs of a plant in- 
 crease on a fertile soil, they diminish on another, where 
 those substances which are necessary for their formation 
 are not so bountifully supplied ; and the proportion of 
 the constituents, which contain nitrogen, and of those 
 which do not, in plants varies with the amount of nitro- 
 geneous matters in their food. 
 
 The development of the stem, leaves, blossoms, and 
 fruit of plants is dependent on certain conditions, the 
 knowledge of which enables us to exercise some influ- 
 ence on their internal constituents as well as on their 
 size. It is the duty of the natural philosopher to dis- 
 cover what these conditions are ; for the fundamental 
 principles of agriculture must be based on a knowledge 
 of them. There is no profession which can be com- 
 pared in importance with that of agriculture, for to it 
 belongs the production of food for man and animals ; 
 on it depends the welfare and development of the whole 
 human species, the riches of states, and all commerce. 
 There is no other profession in which the application of 
 correct principle is productive of more beneficial effects, 
 or is of greater and more decided influence. Hence it 
 appears quite unaccountable, that we may vainly search 
 
188 THE ART OF CULTURE. 
 
 for one leading principle in the writings of agriculturists 
 and vegetable physiologists. 
 
 The methods employed in the cultivation of land are 
 different in every country, and in every district ; and 
 when we inquire the causes of these differences we re- 
 ceive the answer, that they depend upon circumstances. 
 (Les circonstances font les assolemens.) No answer 
 could show ignorance more plainly, since no one has 
 ever yet devoted himself to ascertain what these circum- 
 stances are. Thus also when we inquire in what manner 
 manine acts, we are answered by the most intelligent 
 men, that its action is covered by the veil of Isis ; and 
 when we demand further what this means, we discover 
 merely that the excrements of men and animals are sup- 
 posed to contain an incomprehensible something which 
 assists in the nutrition of plants, and increases tlieir size, 
 this opinion is embraced without even an atten)pt being 
 made to discover the component parts of manure, or to 
 become acquainted with its nature. 
 
 In addition to the general conditions, such as heat, 
 light, moisture, and the component parts of the atmo- 
 sphere, which are necessary for the growth of all plants, 
 certain substances are found to exercise a peculiar in- 
 fluence on the development of particular faniilies. These 
 substances either are already contained in the soil, or are 
 supplied to it in the form of the matters known under 
 the general name of manure. But what does the soil 
 contain, and what are the components of the substances 
 used as manure .'' Until these points are satisfactorily 
 determined, a rational system of agriculture cannot exist. 
 The power and knowledge of the [)hysiologist, of the 
 agriculturist and chemist must be united for the com- 
 
OBJECT OF AGRICULTURE. 189 
 
 plete solution of these questions ; and in order to attain 
 this end, a commencement must be made. 
 
 The general object of agricuhure is to produce in the 
 most advantageous manner certain quahties, or a maxi- 
 mum size, in certain parts or organs of particular plants. 
 Now, this object can be attained only by the application 
 of those substances which we know to be indispensable 
 to the development of these parts or organs, or by sup- 
 plying the conditions necessary to the production of the 
 qualities desired. 
 
 The rules of a rational system of agriculture should 
 enable us, therefore, to give to each plant that which it 
 requires for the attainment of the object in view. 
 
 The special object of agriculture is to obtain an 
 abnormal development and production of certain parts 
 of plants, or of certain vegetable matters, which are 
 employed as food for man and animals, or for the pur- 
 poses of industry. 
 
 The means employed for effecting these two purposes 
 are very different. Thus the mode of culture, employed 
 for the purpose of procuring fine pliable straw for Flo- 
 rentine hats, is the very opposite to that which must be 
 adopted in order to produce a maximum of corn from 
 the same plant. Peculiar methods must be used for the 
 production of nitrogen in the seeds, others for giving 
 strength and solidity to the straw, and others again must 
 be followed when we wish to give such strength and 
 solidity to the straw as will enable it to bear the weight 
 of the ears. 
 
 We must proceed in the culture of plants in precisely 
 the same manner as we do in the fattening of animals. 
 The flesh of the slag and roe, or of wild animals in 
 general, is quite devoid of fat, like the muscular flesh 
 
190 THE ART OF CULTURE. 
 
 of the Arab ; or it contains only small quantities of it. 
 The production of flesh and fat may be artificially in- 
 creased ; all domestic animals, for example, contain much 
 fat. We give food to animals, which increases the 
 activity of certain organs, and is itself capable of being 
 transformed into fat. We add to the quantity of food, 
 or we lessen the processes of respiration and perspira- 
 tion by preventing motion. The conditions necessary 
 to effect this purpose in birds are different from those in 
 quadrupeds ; and it is well known that charcoal powder 
 produces such an excessive growth of the liver of a 
 goose, as at length causes the death of the animal. 
 
 The increase or diminution of the vital activity of 
 vegetables depends only on heat and solar light, which 
 we have not arbitrarily at our disposal : all that we can 
 do is to supply those substances which are adapted for 
 assimilation by the power already present in the organs 
 of the plant. But what then are these substances .'' They 
 may easily be detected by the examination of a soil, 
 which is always fertile in given cosmical and atmospheric 
 conditions ; for it is evident, that the knowledge of its 
 state and composition must enable us to discover the 
 circumstances under which a sterile soil may be rendered 
 fertile. It is the duty of the chemist to explain the 
 composition of a fertile soil, but the discovery of its 
 proper state or condition belongs to the agriculturist ; 
 our present business lies only with the former. 
 
 Arable land is originally formed by the crumbling of 
 rocks, and its properties depend on the nature of their 
 principal component parts. Sand, clay, and lime, are 
 the names given to the principal constituents of the dif- 
 ferent kinds of soil. 
 
 Pure sand and pure limestone, in which there are no 
 
COMPOSITION OF SOILS. 191 
 
 Other inorganic substances except siliceous earth, car- 
 bonate or silicate of lime, form absolutely barren soils. 
 But argillaceous earths form always a part of fertile soils. 
 Now from whence come the argillaceous earths in arable 
 land ; what are their constituents, and what part do they 
 play in favoring vegetation ? They are produced by 
 the disintegration of aluminous minerals by the action of 
 the weather ; the common potash and soda felspars, 
 Labrador spar, mica, and the zeolites, are the most 
 common aluminous earths, which undergo this change. 
 These minerals are found mixed with other substances 
 in granite, gneiss, mica-slate, porphyry, clay-slate, grau- 
 wacke, and the volcanic rocks, basalt, clinkstone, and 
 lava. In the grauwacke, we have pure quartz, clay-slate, 
 and lime ; in the sandstones, quartz and loam. The 
 transition limestone and the dolomites contain an inter- 
 mixture of clay, felspar, porphyry, and clay-slate ; and 
 the mountain limestone is remarkable for the quantity of 
 argillaceous earths which it contains. Jura limestone 
 contains 3 — 20, that of the Wurtemberg Alps 45 — 50 
 per cent, of these earths. And in the muschelkalk and 
 the calcaire grassier they exist in greater or less quan- 
 tity. 
 
 It is known, that the aluminous minerals are the most 
 widely diffused on the surface of the earth, and as we 
 have already mentioned, all fertile soils, or soils capable 
 of culture, contain alumina as an invariable constituent. 
 There must, therefore, be something in aluminous earth 
 which enables it to exercise an influence on the life of 
 plants, and to assist in their development. The prop- 
 erty on which this depends is that of its invariably con- 
 taining potash and soda. 
 
 Alumina exercises only an indirect influence on vege- 
 
192 THE ART OF CULTURE. 
 
 talion, by its power of attraciing and retaining water 
 and ammonia ; it is itself very rarely found in the ashes 
 of plants, but silica is always present, having in most 
 places entered the plants by means of alkalies. In or- 
 der to form a distinct conception of the quantities of 
 alkalies in aluminous minerals it must be remembered 
 that felspar contains 17f per cent, of potash, albite 
 11.43 per cent, of soda, and mica 3 — 5 per cent. ; 
 and that zeolite contains 13 — 16 per cent, of both alka- 
 lies taken together. The late analyses of Ch. Gmelin, 
 Lowe, Fricke, Bleyer, and Redtenbache/r, have also 
 shown, that ^basalt contains from f to 3 per cent, of 
 potash, and from 5 — 7 per cent, of soda, that clay-slate 
 contains from 2.75 — 3.31 per cent, of potash, and 
 loam from 1^ — 4 per cent, of potash. 
 
 If, now, we calculate from these data, and from the 
 specific weights of the different substances, how much 
 potash must be contained in a layer of soil, which has 
 been formed by the disintegration of 40,000 square feet 
 (1 Hessian acre) of one of these rocks to the depth of 
 20 inches, we find that a soil of 
 
 Felspar contains 1,152,000 lbs. 
 
 Clink-stone " from 200,000 to 400,000 " 
 
 Basalt " " 47,500 " 75,000 " 
 
 Clay-slate " " 100,000 " 200,000 " 
 
 Loam " " 87,000 " 300,000 " 
 
 Potash is present in all clays ; according to Fuchs, it is 
 contained even in marl ; it has been found in all the 
 argillaceous earths in which it has been sought. The 
 fact that they contain potash may be proved in the clays 
 of the transition and stratified mountains, as well as in 
 the recent formations surrounding Berlin, by simply di- 
 gesting them with sulphuric acid, by which process 
 
OF THE FERTILITY OF SOILS. 193 
 
 alum is formed. (Mltscherlich.) It is well known 
 also, to all manufacturers of alum, that the leys contain 
 a certain quantity of this salt ready formed, the potash 
 of which has its origin from the ashes of the stone and 
 brown coal, which contain much argillaceous earth. 
 
 When we consider ihis extraordinary distribution of 
 potash over the surface of the earth, is it reasonable to 
 have recourse to the idea, that the presence of this alkali 
 in plants is due to the generation of a metallic oxide by 
 a peculiar organic process from the component parts of 
 the atmosphere. This opinion found adherents even 
 after the method of detecting potash in soils was known, 
 and suppositions of the same kind may be found even in 
 the writings of some physiologists of the present day. 
 Such opinions belong properly to the time when flint 
 was conceived to be a product of chalk, and when every 
 thing, which appeared incomprehensible on account of 
 not having been investigated, was explained by assump- 
 tions far more incomprehensible. 
 
 A thousandth part of loam mixed with the quartz in 
 new red sandstone, or with the lime in the difTerent 
 limestone formations, affords as much potash to a soil 
 only 20 inches in depth as is sufficient to supply a forest 
 of pines growing upon it for a century. A single cubic 
 foot of felspar is sufficient to supply a wood, covering a 
 surface of 40,000 square feet, with the potash required 
 for five years. 
 
 Land of the greatest fertility contains argillaceous- 
 earths and other disintegrated nainerals with chalk and 
 sand, in such a proportion as to give fiee access to air 
 and moisture. The land in the vicinity of Vesuvius 
 may be considered as the type of a fertile soil, and its 
 17 
 
194 THE ART OF CULTURE. 
 
 fertility is greater or less in different parts, according to 
 the proportion of clay or sand which it contains. 
 
 The soil which is formed by the disintegration of lava 
 cannot possibly, on account of its origin, contain the 
 smallest trace of vegetable matter, and yet it is well 
 known, that when the volcanic ashes have been exposed 
 for some time to the influence of air and moisture, a soil 
 is gradually formed in which all kinds of plants grow 
 with the greatest luxuriance. This fertility is owing to 
 the alkalies which are contained in the lava, and which, 
 by exposure to the weather, are rendered capable of 
 being absorbed by plants. Thousands of years have 
 been necessary to convert stones and rocks into the soil 
 of arable land, and thousands of years more will be 
 requisite for their perfect reduction, that is, for the com- 
 plete exhaustion of their alkalies. 
 
 We see from the composition of the water in rivers, 
 streamlets, and springs, how little rain-water is able to 
 extract alkali from a soil, even after a term of years ; 
 this water is generally soft, and the common salt, which 
 even the softest invariably contains, proves that those 
 alkaline salts, which are carried to the sea by rivers and 
 streams, are returned again to the land by wind and rain. 
 
 Nature itself shows us what plants require at the com- 
 mencement of the development of their germs and first 
 radical fibres. Becquercl has shown that the graminea, 
 iFguminosft, cracifcrcE, cichoracccB, umhelUfera^ conifercB, 
 and cucurbitacete emit acetic acid during germination. 
 A plant which has just broken through the soil, and a 
 leaf just burst open from the bud, furnish ashes by in- 
 cineration, which contain as much, and generally more, 
 of alkaline salts than at any period of their life. (De 
 Saussure). Now we know also from the experiments 
 
OF THE FERTILITY OF SOILS. 195 
 
 of Becquerel in what manner these alkaline salts enter 
 young plants ; the acetic acid formed during germina- 
 tion is diffused through the wet or moist soil, becomes 
 saturated with lime, magnesia, and alkalies, and is again 
 absorbed by the radicle fibres in the form of neutral 
 salts. After the cessation of life, when plants are sub- 
 jected to decomposition by means of decay and putre- 
 faction, the soil receives again that which had been 
 extracted from it. 
 
 Let us suppose that a soil has been formed by the 
 action of the weather on the component parts of granite, 
 grauwacke, mountain limestone, or porphyry, and that 
 nothing has vegetated for thousands of years. Now this 
 soil would have become a magazine of alkalies, in a 
 condition favorable for their assimilation by the roots of 
 plants. 
 
 The interesting experiments of Siruve have proved 
 that water impregnated with carbonic acid decomposes 
 rocks which contain alkalies, and then dissolves a part 
 of the alkaline carbonates. It is evident that plants, 
 also, by producing carbonic acid during their decay, 
 and by means of the acids which exude from their roots 
 in the living state, contribute no less powerfully to de- 
 stroy the coherence of rocks. Next to the action of air, 
 water, and change of temperature, plants themselves are 
 the most powerful agents in effecting the disintegration 
 of rocks. 
 
 Air, water, and the change of temperature prepare 
 the different species of rocks for yielding to plants the 
 alkalies which they contain. A soil which has been 
 exposed for centuries to all the influences which effect 
 the disintegration of rocks, but from which the alkalies 
 have not been removed, will be able to afford the means 
 
196 THE ART or CULTURE. 
 
 of nourishment to those vegetables which require alka- 
 lies for its growth during many years ; but it must grad- 
 ually become exhausted, unless those alkalies which 
 have been removed are again replaced ; a period, there- 
 fore, will arrive, when it will be necessary to expose it, 
 from time to time, to a further disintegration, in order 
 to obtain a new supply of soluble alkalies. For small 
 as is the quantity of alkali which plants require, it is 
 nevertheless quite indispensable for their perfect devel- 
 opment. But when one or more years have elapsed 
 without any alkalies having been extracted from the 
 soil, a new harvest may be expected. 
 
 The first colonists of Virginia found a country, the 
 soil of which was similar to that mentioned above ; har- 
 vests of wheat and tobacco were obtained for a century 
 from one and the same field without the aid of manure, 
 but now whole districts are converted into unfruitful 
 pasture land, which without manure produces neither 
 wheat nor tobacco. From every acre of this land, 
 there were removed in the space of one hundred years 
 1,200 lbs. of alkalies in leaves, grain, and straw; it 
 became unfruitful therefore, because it was deprived of 
 every particle of alkali, which had been reduced to a 
 soluble state, and because that which was rendered 
 soluble again in the space of one year, was not sufficient 
 to satisfy the demands of the plants. Almost all the 
 cultivated land in Europe is in this condition ; fallow is 
 the term applied to land left at rest for further disinte- 
 gration. It is the greatest possible mistake to suppose 
 that the temporary diminution of fertility in a soil is 
 owing to the loss of humus ; it is the mere consequence 
 of the exhaustion of the alkalies. 
 
 Let us consider the condition of the country around 
 
OF THE FERTILITY OF SOILS. 197 
 
 Naples, which is famed for its fruitful corn-land ; the 
 farms and villages are situated from 18 to 24 miles dis- 
 tant from one another, and between them there are no 
 roads, and consequently no transportation of manure. 
 Now corn has been cultivated on this land for thousands 
 of years, without any part of that which is annually re- 
 moved from the soil being artificially restored to it. 
 How can any influence be ascribed to humus under 
 such circumstances, when it is not even known whether 
 humus was ever contained in the soil ? 
 
 The method of culture in that district completely ex- 
 plains the permanent fertility. It appears very bad in the 
 eyes of our agriculturists, but there it is the best plan 
 which could be adopted. A field is cultivated once 
 every three years, and is in the intervals allowed to 
 serve as a sparing pasture for cattle. The soil experi- 
 ences no change in the two years during which it there 
 lies fallow, further than that it is exposed to the influ- 
 ence of the weather, by which a fresh portion of the 
 alkalies contained in it are again set free or rendered 
 soluble. The animals fed on these fields yield nothing 
 to these soils which they did not formerly possess. 
 The weeds upon which they live spring from the soil, 
 and that which they return to it as excrement, must 
 always be less than that which they extract. The field, 
 therefore, can have gained nothing from the mere feed- 
 ing of cattle upon them ; on the contrary, the soil must 
 have lost some of its constituents. 
 
 Experience has shown in agriculture, that wheat 
 should not be cultivated after wheat on the same soil, 
 for it belongs with tobacco to the plants which exhaust 
 a soil. But if the humus of a soil gives it the power of 
 producing corn, how happens it that wheat does not 
 17* 
 
19S THE ART OF CULTURE. 
 
 thrive in many parts of Brazil, where the soils are par- 
 ticularly rich in this substance, or in our own climate, 
 in soils formed of mouldered wood ; that its stalk under 
 these circumstances attains no strength, and droops pre- 
 maturely ? The cause is this, — that the strength of 
 the stalk is due to silicate of potash, and that the corn 
 requires phosphate of magnesia, neither of which sub- 
 stances a soil of humus can afford, since it does not 
 contain them ; the plant may indeed, under such cir- 
 cumstances, become an herb, but will not bear fruit. 
 
 Again, how does it happen that wheat does not flour- 
 ish on a sandy soil, and that a calcareous soil is also 
 unsuitable for its growth, unless it be mixed with a 
 considerable quantity of clay ? It is because these soils 
 do not contain alkalies in sufficient quantity, the growth 
 of wheat being arrested by this circumstance, even 
 should all other substances be presented in abundance. 
 
 It is not mere accident that only trees of the fir tribe 
 grow on the sandstone and limestone of the Carpathian 
 mountains and the Jura, whilst we find on soils of 
 gneiss, mica-slate, and granite in Bavaria, of clinkstone 
 on the Rhone, of basalt in Vogelsberge, and of clay- 
 slate on the Rhine and Eifel, the finest forests of other 
 trees which cannot be produced on the sandy or calca- 
 reous soils upon which pines thrive. It is explained by 
 the fact, that trees, the leaves of which are renewed 
 annually, require for their leaves six to ten times more 
 alkalies than the fir-tree or pine, and hence, when they 
 are placed in soils in which alkalies are contained in 
 very small quantity, do not attain maturity.* When we 
 
 * One thousand parts of tlie dry leaves of oaks yielded 55 parts of 
 ashes, of which 24 parts consisted of alkalies soluble in water ; the 
 same quantity of pine leaves gave only 21) parts of ashes, which con- 
 tained 4 6 parts of soluble salts. (De Saussure.) 
 
or THE FERTILITY OF SOILS. 199 
 
 see such trees growing on a sandy or calcareous soil, — 
 the red-beech, the service-tree, and the wild-cherry, 
 for example, thriving luxuriantly on limestone, we may 
 be assured that alkalies are present in the soil, for they 
 are necessary to their existence. Can we, then, regard 
 it as remarkable, that such trees should thrive in Amer- 
 ica, on those spots on which forests of pines which have 
 grown and collected alkalies for centuries, have been 
 burnt, and to which the alkalies are thus at once restor- 
 ed ; or that the Spartium scoparium, Erysimum latifo- 
 lium, Blitum copitaium, Senecio viscosus^ plants re- 
 markable for the quantity of alkalies contained in their 
 ashes, should grow with the greatest luxuriance on the 
 localities of conflagrations.* 
 
 Wheat will not grow on a soil which has produced 
 wormwood, and, vice versa, wormwood does not thrive 
 where wheat has grown, because they are mutually 
 prejudicial by appropriating the alkalies of the soil. 
 
 One hundred parts of the ^alks of wheal yield 15.5 
 parts of ashes (H. Davy) ; the same quantity of the 
 dry stalks of barley, 8. 54 parts (^Schrader) ; and one 
 hundred parts of the stalks of oats, only 4.42 ; — the 
 ashes of all these are of the same composition. 
 
 We have in these facts a clear proof of what plants 
 require for their growth. Upon the same field, which 
 will yield only one harvest of wheat, two crops of bar- 
 ley and three of oats may be raised. 
 
 * After the great fire in London, large quantities of the Erysimum 
 latifolium were observed growing on the spots where a fire had taken 
 place. On a similar occasion, the Blitum capitalum was seen at 
 Copenhagen, the Senecio viscosus in Nassau, and the Spartium sco- 
 •parium in Languedoc. After the burnings of forests of pines in 
 North America poplars grew on the same soil. {Franklin) 
 
200 THE ART OF CULTURE. 
 
 AH plants of the grass kind require silicate of potash. 
 Now this is conveyed to the soil, or rendered soluble in 
 it by the irrigation of meadows. The equisetacecBj the 
 reeds and species of cane, for example, which contain 
 such large quantities of siliceous earth, or silicate of pot- 
 ash, thrive luxuriantly in marshes, in argillaceous soils, 
 and in ditches, streamlets, and other places, where the 
 change of water renews constantly the supply of dis- 
 solved sihca. The amount of silicate of potash removed 
 from a meadow, in the form of hay, is very considerable. 
 We need only call to mind the melted vitreous mass 
 found on a meadow between INfanheim and Heidelberg 
 after a thunder-storm. This mass was at first supposed 
 to be a meteor, but was found on examination (by 
 Gmeliii) to consist of silicate of potash ; a flash of 
 lightning had struck a stack of hay, and nothing was found 
 in its place except the melted ashes of the hay. 
 
 Potash is not the only substance necessary for the ex- 
 istence of most plants, indeed it has been already shown 
 that the potash may be replaced, in many cases, by soda, 
 magnesia, or lime ; but other substances, besides alkalies, 
 are required to sustain the life of plants. 
 
 Phosphoric acid has been found in the ashes of all 
 plants hitherto examined, and always in combination with 
 alkalies or alkaline earths. Most seeds contain certain 
 quantities of phosphates. In the seeds of different kinds 
 of corn, particularly, there is abundance of phosphate of 
 magnesia. 
 
 Plants obtain their phosphoric acid from the soil. It 
 is a constituent of all land capable of cultivation, and 
 even the heath at Liineburg contains it in appreciable 
 quantity. Phosphoric acid has been detected, also, in 
 all mineral waters in which its presence has been tested ; 
 
OF THE FERTILITY OF SOILS, 201 
 
 and in those in which it has not been found, it has not 
 been sought for. The most superficial strata of the de- 
 posits of sulphuret of lead (galena) contain crystallized 
 phosphate of lead (greenlead ore) ; clay-slate, which 
 forms extensive strata, is covered in many places with 
 crystals of phosphate of alumina ( ff^avellite) ; all its 
 fractured surfaces are overlaid with it. Phosphate of 
 lime (Apatite) is found even in the volcanic bowlders on 
 the Laacher See in the Eifel, near Andernach. 
 
 The soil in which plants grow furnishes them with 
 phosphoric acid, and they in turn yield it to animals, to 
 be used in the formation of their bones, and of those 
 constituents of the brain which contain phosphorus. 
 Much more phosphorus is thus afforded to the body than 
 it requires, when flesh, bread, fruit, and husks of grain 
 are used for food, and this excess in them is eliminated 
 in the urine and the solid excrements. We may form 
 an idea of the quantity of phosphate of magnesia con- 
 tained in grain, when we consider that the concretions 
 in the coecum of horses consist of phosphate of mag- 
 nesia and ammonia, which must have been obtained 
 from the hay and oats consumed as food. Twenty- 
 nine of these stones were taken after death from the 
 rectum of a horse belonging to a miller in Eberstadt, the 
 total weight of which amounted to 31bs. ; and Dr. F. 
 Simon has lately described a similar concretion found in 
 the horse of a carrier, which weighed Iglb. 
 
 It is evident that the seeds of corn could not be form- 
 ed without phosphate of magnesia, whicU is one of their 
 invariable constituents ; the plant could not under such 
 circumstances, reach maturity. 
 
 Some plants, however, extract other matters from the 
 soil besides silica, potash, and phosphoric acid, which 
 
202 THE ART OF CULTURE. 
 
 are essential constituents of the plants ordinarily culti- 
 vated. These other matters, we must suppose, supply, 
 in part at least, the place and perform the function of 
 the substances just named. We may thus regard com- 
 mon salt, sulphate of potash, nitre, chloride of potassi- 
 um, and olher matters, as necessary constituents of 
 several plants. 
 
 Clay-slate contains generally small quantities of oxide 
 of copper ; and soils formed from micaceous schist con- 
 tain some metallic fluorides. Now, small quantities of 
 these substances also are absorbed into plants, although 
 we cannot affiim that they are necessary lo them. 
 
 It appears that, in certain cases, fluoride of calcium* 
 may take the place of the phosphate of lime in the bones 
 and teeth ; f at least, it is impossible otherwise to explain 
 
 * Fluorine is the base of the acid contained in Fluor or Derbyshire 
 spar ; with hydrogen it forms the hydrofluoric acid. The acid is sepa- 
 rated by heating fluor spar with sulphuric acid, and is distinguished 
 by its power of corroding glass, and of uniting with its silica. Com- 
 pounds of Fluorine are called Fluorides, of the acid Hijdrofluates. 
 Calcium is the base of lime. 
 
 ! The earthy parts of bones are composed principally of the phos- 
 phate and carbonate of lime in various proportions, variable in differ- 
 ent animals, and mixed with small quantities, equally variable, of 
 phosphate of magnesia and fluate of lime. By acting upon calcined 
 bones with sulphuric acid fluoric acid is disengaged. The following 
 analyses of the bones of man and horned cattle, are given by Ber- 
 
 zelius. 
 
 Human bone. Ox bone. 
 
 Cartilage soluble in water, . . . 32.17 ) 03 on 
 
 Vessels, ....... 1.13 J 
 
 Subphosphate, and a little fluate of lime, . 53.04 57.35 
 
 Carbonate of lime, 11.30 3.85 
 
 Phosphate of magnesia, . . . . 1.16 2 05 
 
 Soda and very little muriate of soda, . . 1 20 3.45 
 
 10000 100.00 
 
 The bones of man contain three times as much carbonate of lime 
 
FALLOW-CROPS. 203 
 
 its constant presence in the bones of antediluvian animals, 
 by which they are distinguished from those of a later 
 period. The bones of human skulls found at Pompeii 
 contain as much fluoric acid as those of animals of a for- 
 mer world, for if they be placed in a state of powder in 
 glass vessels, and digested with sulphuric acid, the interior 
 of the vessel will, after twenty-four hours, be found 
 powerfully corroded (Liebig) ; whilst the bones and 
 teeth of animals of the present day contain only traces 
 of it (^Berzelius) . 
 
 Dt Saussure remarked, that plants require unequal 
 quantities of the component parts of soils in different 
 stages of their development ; an observation of much 
 importance in considering the growth of plants. Thus, 
 wheat yielded xl^-o of ashes a month before blossoming, 
 yllg while in blossom, and y§|o after the ripening of 
 the seeds. It is therefore evident, that wheat from the 
 
 as those of the ox, and the latter are richer in phosphate of lime and 
 magnesia in the same proportion. 
 
 The following are the relative proportions of phosphate and car- 
 bonate of lime in bones of different animals, according lo De Barros. 
 Phosphate of Lime. Carbonate of Lime. 
 Lion, .... 95.0 2.5 
 
 Sheep, .... 80.0 19,3 
 
 Hen, .... 88.9 10.4 
 
 Frog 95.2 2.4 
 
 Fish, .... 91.9 5.3 
 
 The enamel of the teeth is composed of 
 
 
 Human. 
 
 Ox. 
 
 Phosphate of lime, 
 
 . 88.5 
 
 85.0 
 
 Carbonate of " . . 
 
 8.0 
 
 7.1 
 
 Phosphate of magnesia. 
 
 . 1.5 
 
 3.0 
 
 Soda, .... 
 
 0.0 
 
 1.4 
 
 Membrane, alkali and water, 
 
 . 2.0 
 
 3.5 
 
 100.0 100.0 
 
204 THE ART OF CULTURE. 
 
 time of its flowering restores a part of its organic con- 
 stituents to the soil, althougli the phosphate of magnesia 
 remains in the seeds. 
 
 The fallow-time, as we have already shown, is that 
 period of culture, during which land is exposed to a pro- 
 gressive disintegration by means of the influence of the 
 atmosphere, for the purpose of rendering a certain quan- 
 tity of alkalies capable of being appropriated by plants. 
 
 Now, it is evident, that the careful tilling of fallow 
 land must increase and accelerate this disintegration. 
 For the purpose of agriculture, it is quite indifferent, 
 whether the land is covered with weeds, or with a plant 
 which does not abstract the potash enclosed in it. Now 
 many plants in the family of the leguminosce^ are remarka- 
 ble on account of the small quantity of alkalies or salts 
 in general, which they contain ; the Vicia faba (Wind- 
 sor bean), for example, contains no free alkalies, and not 
 one per cent, of the phosphates of lime and magnesia. 
 (Einhof.) The bean of the Phaseolus Vulgaris (Kid- 
 ney bean) contains only traces of salts. [Braconnot.) 
 The stem of the Medicago saliva (Lucerne) contains 
 only 0.83 per cent., that of the Ervum lens (Lentil) 
 only 0.57 of phosphate of lime with albumen. [Crome.) 
 Buck-wheat dried in the sun yields only 0.681 per cent. 
 of ashes, of which 0.09 parts are soluble salts. {Zennech) .* 
 These plants belong to those which are termed fallow- 
 crops, and the cause wherefore they do not exercise any 
 
 * The small quantity of phosphates which the seeds of the lentils, 
 beans and peas contain, must be the cause of their small value as 
 articles of nourishment, since they surpass all other vegetable food in 
 the quantity of nitrogen which enters into their composition. But 
 as the component parts of the bones (phosphate of lime and magnesia) 
 are absent, they satisfy the appetite without increasing the strength. — L. 
 
FALLOW-CROPS. 205 
 
 injurious influence on corn which is cultivated immedi- 
 ately after them is, that they do not extract the alkalies 
 of the soil, and only a very small quantity of phosphates. 
 
 It is evident that two plants growing beside each other 
 will mutually injure one another, if they withdraw the 
 same food from the soil. Hence it is not surprising that 
 the Matricaria chamomiUa (Wild Chamomile) and Spar- 
 Hum scoparium (Scotch Broom) impede the growth of 
 corn, when it is considered that both yield from 7 to 
 7.43 per cent, of ashes, which contain j% of carbonate 
 of potash. The darnel, and the Erigeron acre (Flea- 
 bane), blossom and bear fruit at the same time as 
 the corn, so that when growing mingled with it, they will 
 partake of the component parts of the soil, and in pro- 
 portion to the vigor of their growth, that of the corn 
 must decrease ; for what one receives, the others are de- 
 prived of. Plants will, on the contrary, thrive beside 
 each other, either when the substances necessary for their 
 growth which they extract from the soil are of different 
 kinds, or when they themselves are not both in the same 
 stages of development at the same time. 
 
 On a soil, for example, which contains potash, both 
 wheat and tobacco may be reared in succession, because 
 the latter plant does not require phosphates, salts which 
 are invariably present in wheat, but requires only alkalies, 
 and food containing nitrogen. 
 
 According to the analysis of Posselt and Reimanriy 
 10,000 parts of the leaves of the tobacco-plant contain 
 16 parts of phosphate of lime, 8.8 parts of silica, and 
 no magnesia ; whilst an equal quantity of wheat-straw 
 contains 47.3 parts, and the same quantity of the grain 
 of wheat 99.45 parts of phosphates. [De Saussure.) 
 
 Now, if we suppose that the grain of wheat is equal 
 18 
 
206 THE INTERCHANGE OF CROPS. 
 
 to half the weight of its straw, then the quantity of phos- 
 phates extracted from a soil by the same weights of 
 wheat and tobacco must be as 97.7 : 16. This differ- 
 ence is very considerable. The roots of tobacco, as 
 well as those of wheat, extract the phosphates contained 
 in the soil, but they restore them again, because they 
 are not essentially necessary to the development of the 
 plant. 
 
 CHAPTER VIII. 
 
 ON THE INTERCHANGE OP CROPS, AND OF MANURE. 
 
 It has long since been found by experience, that the 
 growth of annual plants is rendered imperfect, and their 
 crops of fruit or herbs less abundant, by cultivating them 
 in successive years on the same soil, and that, in spite 
 of the loss of time, a greater quantity of grain is obtain- 
 ed, when a field is allowed to be uncultivated for a year. 
 During this interval of rest, the soil,* in a great measure, 
 regains its original fertility. 
 
 It has been further observed, that certain plants, such 
 as peas, clover, and. flax, thrive on the same soil only 
 after a lapse of years ; whilst others, such as hemp, to- 
 bacco, helianthus tuberosus, rye, and oats, may be cul- 
 tivated in close succession when proper manure is used. 
 It has also been found, that several of these plants im- 
 prove the soil, whilst others, and these are the most nu- 
 merous, impoverish or exhaust it. Fallow turnips, cab- 
 bage, beet, spelt, summer and winter barley, rye, and 
 oats, are considered to belong to the class which impov- 
 erish a soil ; whilst by wheat, hops, madder, late turnips. 
 
THEORIES OF ITS USE. 207 
 
 hemp, poppies, teasel, flax, weld, and licorice, it is sup- 
 posed to be entirely exhausted. 
 
 The excrements of man and animals have been em- 
 ployed from the earliest times for the purpose of increas- 
 ing the fertility of soils ; and it is completely established 
 by all experience, that they restore certain constituents 
 to the soil which are removed with the roots, fruit, or 
 grain, or entire plants grown upon it. 
 
 But it has been observed that the crops are not al- 
 ways abundant in proportion to the quantity of manure 
 employed, even although it may have been of the most 
 powerful kind ; that the produce of many plants, for 
 example, diminishes, in spite of the apparent replace- 
 ment of the substances removed from the soil by ma- 
 nure, when they are cultivated on the same field for sev- 
 eral years in succession. 
 
 On the other hand it has been remarked, that a field 
 which has become unfitted for a certain kind of plants 
 was not on that account unsuited for another ; and upon 
 this observation, a system of agriculture has been gradu- 
 ally founded, the principal object of which is to obtain 
 the greatest possible produce with the least expense of 
 manure. 
 
 Now it was deduced from all the foregoing facts that 
 plants require for their growth different constituents of 
 soil, and it was very soon perceived, that an alternation 
 of the plants cultivated maintained the fertility of a soil 
 quite as well as leaving it at rest or fallow. It was evi- 
 dent that all plants must give back to the soil in which 
 ihey grow different proportions of certain substances, 
 which are capable of being used as food by a succeed- 
 ing generation. 
 
 But agriculture has hitherto never sought aid from 
 
208 THE INTERCHANGE OF CROPS. 
 
 chemical principles, based on the knowledge of those 
 substances which plants extract from the soil on which 
 they grow, and of those restored to the soil by means of 
 manure. The discovery of such principles will be the 
 task of a future generation, for what can be expected 
 from the present, which recoils with seeming distrust 
 and aversion from all the means of assistance offered it 
 by chemistry, and which does not understand the art of 
 making a rational application of chemical discoveries ? 
 A future generation, however, will derive incalculable 
 advantage from these means of help. 
 
 Of all the views which have been adopted regarding 
 the cause of the favorable effects of the alternations of 
 crops, that proposed by M. DecanJolIe alone deserves 
 to be mentioned as resting on a firm basis. 
 
 DecandoUe supposes that the roots of plants imbibe 
 soluble matter of every kind from the soil, and thus 
 necessarily absorb a number of substances which are 
 not adapted to the purposes of nutrition, and must sub- 
 sequently be expelled by the roots, and returned to the 
 soil as excrements. Now as excrements cannot be as- 
 similated by the plant which ejected them, the more of 
 these matters which the soil contains, the more unfertile 
 must it be for plants of the same species. These excre- 
 mentitious matters may, however, still be capable of 
 assimilation by another kind of plants, which would thus 
 remove them from the soil, and render it aH,ain fertile 
 for the first. And if the plants last grown also expel 
 substances from their roots, which can be appropriated 
 as food by the former, they will improve the soil in two 
 ways. 
 
 Now a great number of facts appear at first sight to 
 give a high degree of probability to this view. Every 
 
THEORIES OF ITS USE. 209 
 
 gardener knows that a fruit-tree cannot be made to grow 
 on the same spot where another of the same species has 
 stood ; at least not until after a lapse of several years. 
 Before new vine-stocks are planted in a vineyard from 
 which the old have been rooted out, other plants are 
 cultivated on the soil for several years. In connexion 
 with this it has been observed, that several plants thrive 
 best when growing beside one another ; and on the con- 
 trary, that others mutually prevent each other's devel- 
 opment. Whence it was concluded, that the beneficial 
 influence in the former case depended on a mutual inter- 
 change of nutriment between the plants, and the injuri- 
 ous one in the latter on a poisonous action of the excre- 
 ments of each on the other respectively. 
 
 A series of experiments by Alacaire-Princep gave 
 great weight to this theory. He proved beyond all 
 doubt that many plants are capable of emitting extractive 
 matter from their roots. He found that the excretions 
 were greater during the night than by day (?), and that 
 the water in which plants of the family of the Legiimi- 
 nosce grew, acquired a brown color. Plants of the 
 same species, placed in water impregnated with these 
 excrements, were impeded in their growth, and faded 
 prematurely, whilst, on the contrary, corn-plants grew 
 vigorously in it, and the color of the water diminished 
 sensibly ; so that it appeared, as if a certainquantity of 
 the excrements of the Leguminosce had really been ab- 
 sorbed by the corn-plants. These experiments afforded 
 as their main result, that the characters and properties 
 of the excrements of different species of plants are dif- 
 ferent from one another, and that some plants expel 
 excrementitious matter of an acrid and resinous charac- 
 ter ; others mild {douce) substances resembling gum. 
 18* 
 
210 THE INTERCHANGE OF CROPS. 
 
 The former of these, according to JMacnire-Princep, 
 may be regarded as poisonous, the latter as nutritious. 
 
 The experiments of Macaire-Princep are positive 
 proof that the roots, probably of all plants, expel mat- 
 ters, which cannot be converted in their organism 
 either into woody fibre, starch, vegetable albumen, or 
 gluten, since their expulsion indicates that they are 
 quite unfitted for this purpose. But they cannot be 
 considered as a confirmation of the theory of Decan- 
 dolle, for they leave it quite undecided whether the sub- 
 stances were extracted from the soil, or formed by the 
 •plant itself from food received from another source. It 
 •is certain that the gummy and resinous excrements ob- 
 served by Macaire-Princep could not have been con- 
 tained in the soil ; and as we know that the carbon of a 
 soil is not diminished by culture, but, on the contrary, 
 increased, we must conclude, that all excrements which 
 contain carbon must be formed from the food obtained 
 by plants from the atmosphere. Now, these excre- 
 ments are compounds, produced in consequence of the 
 transformations of the food, and of the new forms which 
 it assumes by entering into the composition of the vari- 
 ous organs. 
 
 M. Decandol/e^s theory is properly a modification of 
 an earlier hypothesis, which supposed that the roots of 
 different plants extracted different nutritive substances 
 from the soil, each plant selecting that which was ex- 
 actly suited for its assimilation. According to this 
 hypothesis, the matters incapable of assimilation are not 
 extracted from the soil, whilst M. Decandolle considers 
 that they are returned to it in the form of excrements. 
 Both views explain how it happens that after corn, corn 
 cannot be raised with advantage, nor after peas, peas ; 
 
THEORIES OF ITS USE. 211 
 
 but they do not explain how a field is improved by ly- 
 ing fallow, and this in proportion to the care with which 
 it is tilled and kept free from weeds ; nor do they show 
 how a soil gains carbonaceous matter by the cultivation 
 of certain plants, such as lucern and esparsette. 
 
 Theoretical considerations on the process of nutrition, 
 as well as the experience of all agriculturists, so beau- 
 tifully illustrated by the experiments of Macaire-Prin- 
 cep^ leave no doubt that substances are excreted from 
 the roots of plants, and that these matters form the 
 means by which the carbon received from humus in the 
 early period of their growth, is restored -to the soil. 
 But we may now inquire whether these excrements in 
 the state in which they are expelled, are capable of be- 
 ing employed as food by other plants. 
 
 The excrements of a carnivorous animal contain no 
 constituents fitted for the nourishment of another of the 
 same species ; but it is possible that an herbivorous an- 
 imal, a fish, or a fowl, might find in them undigested 
 matters, capable of being digested in their organism, 
 from the very circumstance of their organs of digestion 
 having a different structure. This is the only sense in 
 which we can conceive that the excrements of one ani- 
 mal could yield matter adapted for the nutrition of an- 
 other. 
 
 A number of substances contained in the food of 
 animals pass through their alimentary organs without 
 change, and are expelled from the system ; these are 
 excrements but not excretions. Now a part of such 
 excrementitious matter might be assimilated in passing 
 through the digestive apparatus of another animal. Th** 
 organs of secretion form combinations of which only the 
 elements were contained in the food. The production 
 
212 THE INTERCHANGE OF CROPS. 
 
 of these new compounds is a consequence of the 
 changes which the food undergoes in becoming chyle 
 and chyme, and of the further transformations to which 
 these are subjected by entering into the composition of 
 the organism. These matters, hkewise, are ehminated in 
 the excrements, which must therefore consist of two dif- 
 ferent kinds of substances, namely, of the indigestible 
 constituents of the food, and of the new compounds 
 formed by the vital process. The latter substances have 
 been produced in consequence of the formation of fat, 
 muscular fibre, cerebral and nervous substance, and are 
 quite incapable of being "converted into the same sub- 
 stances in any other animal organism. 
 
 Exactly similar conditions must subsist in the vital 
 processes of plants. When substances, wliich are inca- 
 pable of being employed in the nutrition of a plant, ex- 
 ist in the matter absorbed by its roots, they must be 
 again returned to the soil. Such excrements might be 
 serviceable and even indispensable to the existence of 
 several other plants. But substances that are formed in 
 a vegetable organism during the process of nutrition, 
 which are produced, therefore, in consequence of the 
 formation of woody fibre, starch, albumen, gum, acids, 
 &ic., cannot again serve in any other plants to form the 
 same constituents of vegetables. 
 
 The consideration of these facts enables us to distin- 
 guish the difference between the views of DccandoUe 
 and those of Macaire-Princep. The substances which 
 the former physiologist viewed as excrements, belonged 
 to the soil ; they were undigested matters, which, al- 
 though not adapted for the nutrition of one plant, might 
 yet be indispensable to another. Those matters, on 
 the contrary, designated as excrements by Macaire- 
 
CAUSES OF ITS BENEFICIAL INFLUENCE. 213 
 
 Princep^ could only in one form serve for the nutrition 
 of vegetables. It is scarcely necessary to remark, that 
 this excrementitious matter must undergo a change be- 
 fore another season. During autumn and winter it begins 
 to suffer a change from the influence of air and water ; 
 its putrefaction, and at length, by continued contact with 
 the air, which tillage is the means of procuring, its de- 
 cay are effected ; and at the commencement of spring 
 it has become converted, either in whole or in part, into 
 a substance which supplies the place of humus, by be- 
 ing a constant source of carbonic acid. 
 
 The quickness with which this decay of the excre- 
 ments of plants proceeds, depends on the composition 
 of the soil, and on its greater or less porosity. It will 
 take place very quickly in a calcareous soil ; for the 
 power of organic excrements to attract oxygen and to 
 putrefy is increased by contact with the alkaline constit- 
 uents, and by the general porous nature of such kinds 
 of soil, which freely permit the access of air. But it 
 requires a longer time in heavy soils consisting of loam 
 or clay. 
 
 The same plants can be cultivated with advantage on 
 one soil after the second year, but in others not until the 
 fifth or ninth, merely on account of the change and de- 
 struction of the excrements which have an injurious in- 
 fluence on the plants being completed in the one, in the 
 second year ; in the others, not until the ninth. 
 
 In some neighbourhoods, clover will not thrive till 
 the sixth year ; in others not till the twelfth ; flax in the 
 second or third year. All this depends upon the chem- 
 ical nature of the soil ; for it has been found by expe- 
 rience, that in those districts where the intervals at 
 which the same plants can be cultivated with advantage, 
 
214 THE INTERCHANGE OF CROPS. 
 
 are very long, the time cannot be shortened even by the 
 use of the most powerful manures. The destruction of 
 the peculiar excrements of one crop must have taken 
 place before a new crop can be produced. 
 
 Flax, peas, clover, and even potatoes, are plants the 
 excrements of which, in argillaceous soils, require the 
 longest time for their conversion into humus ; but it is 
 evident, that the use of alkalies and burnt lime, or even 
 small quantities of ashes which have not been lixiviated, 
 must enable a soil to permit the culivation of the same 
 plants in a much shorter time. 
 
 A soil lying fallow owes its earlier fertility, in part, to 
 the destruction or conversion into humus of the excre- 
 ments contained in it, which is effected during the fallow 
 season, at the same time that the land is exposed to a 
 further disintegration. 
 
 In the soils in the neighbourhood of the Rhine and 
 Nile, which contain much potash, and where crops can 
 be obtained in close succession from the same field, the 
 fallowing of the land is superseded by the inundation ; 
 the irrigation of meadows effects the same purpose. It 
 is because the water of rivers and streams contains oxygen 
 in solution, that it effects the most complete and rapid 
 putrefaction of the excrements contained in the soil 
 which it penetrates, and in which it is continually re- 
 newed. If it was the water alone which produced this 
 effect, marshy meadows should be the most fertile. 
 
 It follows from what has preceded, that the advantage 
 of the alternation of crops is owing to two causes. 
 
 A fertile soil ought to afford to a plant all the inorganic 
 bodies indispensable for its existence in sufiicient quan- 
 tity and in such condition as allows their absorption. 
 
 All plants require alkalies, which are contained in 
 
CAUSES OF ITS BENEFICIAL INFLUENCE. 215 
 
 some, in the graminece for example, in the form of sili- 
 cates, in others, in that of tartrates, citrates, acetates, 
 or oxalates. 
 
 When these alkalies are in combination with silicic 
 acid, the ashes obtained by the incineration of the plant 
 contain no carbonic acid ; but when they are united with 
 organic acids, the addition of a mineral acid to their 
 ashes causes an effervescence. 
 
 A third species of plants requires phosphate of lime, 
 another, phosphate of magnesia, and several do not thrive 
 without carbonate of lime. 
 
 Silicic acid * is the first solid substance taken up by 
 plants ; it appears to be the material from which the 
 
 * Silica, or siliceous earth is the most abundant ingredient in the 
 mineral kingdom, being one of the constituents of most rocks, and 
 extensively distributed over the earth in the form of sand, quartz, 
 carnelian, flint, &c., &c. It is also held in solution by the water 
 of hot springs, as in the Geysers of Iceland, and the Azores, from 
 which it is deposited, forming what is called siliceovs sinter, and often 
 encrusting the stems of plants and other bodies. The vegetable mat- 
 ter in some instances has entirely disappeared, and the silica having 
 taken its place we have silicified or petrified wood, &c. See Webster's 
 Description of the Island of St. Michael, p. 208. From silcia a sub- 
 stance is obtained which is considered as its base, and called silicon 
 and silicivm. This base combined with oxygen, constitutes silica, 
 which is capable of combining with other bases; from this and other 
 properties it is called silicic acid. By combination with other sub- 
 stances, as potash, soda, &c , silica becomes soluble in water. These 
 compounds are called silicates. A while, earthy substance is found 
 beneath peat and in swampy land and ponds, which has long been 
 mistaken for calcareous marl. It has been proved to consist of the 
 siliceous skeletons of " infusorial vegetables, if they may be so called, 
 or of those equivocal beings which occupy the borders of the two 
 kingdoms, and render it difficult, not to say impossible, to draw the 
 line between them." This siliceous deposit has been found under 
 nearly every peat bog in this country which has been examined. See 
 Professor Bailey's paper in American Journal of Science, Vol. XXXV. 
 p. 118, and Vol. XL. p. 174. 
 
216 THE INTERCHANGE OF CROPS. 
 
 formation of the wood lakes its origin, acting like a grain 
 of sand around which the first crystals form in a solution 
 of a salt which is in the act of crystallizing. Silicic 
 acid appears to perform the function of woody fibre in 
 the EquisetacecB and bamboos, just as the crystalline 
 salt, oxalate of lime, does in many of the lichens. 
 
 When we grow in the same soil for several years 
 in succession different plants, the first of which leaves 
 behind that which the second, and the second that which 
 the third may require, the soil will be a fruitful one for 
 all the three kinds of produce. If the first plant, for 
 example, be wheat, which consumes the greatest part of 
 the silicate of potash in a soil, whilst the plants which 
 succeed it are of such a kind as require only small quan- 
 tities of potash, as is the case with the Legmninosce, 
 turnips, potatoes, &c. ; the wheat may be again sowed 
 with advantage after the fourth year ; for, during the in- 
 terval of three years, the soil will, by the action of the 
 atmosphere, be rendered capable of again yielding silicate 
 of potash in sufl!icient quantity for the young plants. 
 
 The same precautions must be observed with regard 
 to the other inorganic constituents, when it is desired to 
 grow different plants in succession on the same soil ; for 
 a successive growth of plants which extract the same 
 component parts, must gradually render it incapable of 
 producing them. Each of these plants, during its growth, 
 returns to the soil a certain quantity of substances con- 
 taining carbon, which are gradually converted into humus, 
 and are for the most part equivalent to as much carbon 
 as the plants had formerly extracted from the soil in the 
 state of carbonic acid. But although this is sufiicient 
 to bring many plants to maturity, it is not enough to 
 furnish their different organs with the greatest possible 
 
CAUSES OF ITS BENEFICIAL INFLUENCE. 217 
 
 supply of nourishment. Now the object of agriculture 
 is to produce either articles of commerce, or- food for 
 man and animals, but a maximum of produce in plants is 
 always in proportion to the quantity of nutriment supplied 
 to them in the first stage of their development. 
 
 The nutriment of young plants consists of carbonic 
 acid, contained in the soil in ihe form of humus, and 
 of nitrogen in the form of ammonia, both of which must 
 be supplied to the plants if the desired purpose is to be 
 accomplished. The formation of ammonia cannot be 
 effected on cultivated land, but humus may be artificially 
 produced ; and this must be considered as an important 
 object in the alternation of crops, and as the second reason 
 of its peculiar advantages. 
 
 The sowing of a field with fallow plants, such as 
 clover, rye, buck-wheat, &c. and the incorporation of 
 the plants, when nearly at blossom, with the soil, affect 
 this supply of humus in so far, that young plants subse- 
 qently growing in it find, at a certain period of their 
 growth, a maximum of nutriment, that is, matter ig the 
 process of decay. 
 
 The same end is obtained, but with much greater 
 certainty, when the field is planted with esparsette (sain- 
 foin) or lucern. These plants are remarkable on account 
 of the great ramification of their roots, and strong devel- 
 opment of their leaves, and for requiring only a small; 
 quantity of inorganic matter. Until they reach a certain 
 period of their growth, they retain all the carbonic acid 
 and ammonia which may have been conveyed to them 
 by rain and the air, for that which is not absorbed by the 
 soil is appropriated by the leaves : they also possess an 
 extensive four or six fold surface capable of assimilating 
 19 
 
218 THE INTERCHANGE OF CROPS. 
 
 these bodies, and of preventing the volatih'zation of the 
 ammonia from the soil, by completely covering it in. 
 
 An immediate consequence of the production of the 
 green principle of the leaves, and of their remaining 
 component parts, as well as of those of the stem, is the 
 equally abundant excretion of organic matters into the 
 soil from the roots. 
 
 The favorable influence which this exercises on the 
 land, by furnishing it with matter capable of being con- 
 verted into humus lasts for several years, but barren 
 spots gradually appear after the lapse of some time. 
 Now, it is evident, that after from six to seven years the 
 ground must become so impregnated with excrements 
 that every fibre of the root will be surrounded with 
 them. As they remain for some lime in a soluble con- 
 dition, the plants must absorb part of them and suffer 
 injurious effects in consequence, because they are not 
 capable of assimilation. When such a field is observed 
 for several years, it is seen, that the barren spots are 
 again covered with vegetation, (the same plants being 
 always supposed to be grown,) whilst new spots become 
 bare and apparently unfruitful, and so on alternately. 
 The causes which produce this alternate barrenness and 
 fertility in the different parts of the land are evident. 
 The excrements upon the barren spots receiving no 
 new addition, and being subjected to the influence of 
 air and moisture, they pass into putrefaction, and their 
 injurious influence ceases. The plants now find those 
 substances, which formerly prevented their growth re- 
 moved, and in their place meet with humus, that is, 
 vegetable matter in the act of decay. 
 
 We can scarcely suppose a better means of produ- 
 cing humus than by the growth of plants, the leaves of 
 
CAUSES OF ITS BENEFICIAL INFLUENCE. 219 
 
 which are food for animals ; for they prepare the soil 
 for plants of every other kind, but particularly for those 
 to which, as to rape and flax, the presence of humus is 
 the most essential condition of growth. 
 
 The reasons why this interchange of crops is so ad- 
 vantageous, — the principles which regulate this part of 
 agriculture, are, therefore, the artificial production of 
 humus, and the cultivation of different kinds of plants 
 upon the same field, in such an order of succession, 
 that each shall extract only certain components of the 
 soil, whilst it leaves behind or restores those which a 
 second or third species of plant may require for its 
 growth and perfect development. 
 
 Now, although the quantity of humus in a soil may be 
 increased to a certain degree by an artificial cultivation, 
 still, in spite of this, there cannot be the smallest doubt 
 that a soil must gradually lose those of its constituents 
 which are removed in the seeds, roots, and leaves of 
 the plants raised upon it. The fertility of a soil cannot 
 remain unimpaired, unless we replace in it all those 
 substances of which it has been thus deprived. 
 
 Now this is effected by manure. 
 
 When it is considered that every constituent of the 
 body of man and animals is derived from plants, and 
 that not a single element is generated by the vital prin- 
 ciple, it is evident that all the inorganic constituents of 
 the animal organism must be regarded, in some respect 
 or other, as manure. During their life, the inorganic 
 components of plants which are not required by the 
 animal system, are disengaged from the organism, in the 
 form of excrements. After their death, their nitrogen 
 and carbon pass into the atmosphere as ammonia and 
 carbonic acid, the products of their putrefaction, and at 
 
220 OF MANURE. 
 
 last nothing remains except the phosphate of lime and 
 other salts in their bones.* Now this earthy residue of 
 the putrefaction of animals must be considered in a ra- 
 tional system of agriculture, as a powerful manure for 
 plants, because that which has been abstracted from a 
 soil for a series of years must be restored to it, if the 
 land is to be kept in a permanent condition of fertility. 
 
 We may now inquire whether the excrements of an- 
 imals, which are employed as manure, are all of a like 
 nature and power, and whether they, in every case, ad- 
 minister to the necessities of a plant by an identical 
 mode of action. These points may easily be deter- 
 mined by ascertaining the composition of the animal 
 excrements, because we shall thus learn what substances 
 a soil really receives by their means. According to 
 the common view, the action of solid animal excrements 
 depends on the decaying organic matters which replace 
 the humus, and on the presence of certain compounds 
 of nitrogen, which are supposed to be assimilated by 
 plants, and employed in the production of gluten and 
 other azotized substances. But this view requires fur- 
 ther confirmation with respect to the solid excrements 
 of animals, for they contain so small a proportion of 
 nitrogen, that they cannot possibly by means of it exer- 
 cise any influence upon vegetation. 
 
 We may form a tolerably correct idea of the chem- 
 ical nature of animal excrement without further exami- 
 nation, by comparing the excrements of a dog with its 
 food. When a dog is fed with flesh and bones, both of 
 which consist in great part of organic substances con- 
 taining nitrogen, a moist white excrement is produced 
 
 * See note, p. 202. 
 
COMPOSITION OF ANIMAL MANURES. 221 
 
 which crumbles gradually to a dry powder in the air. 
 This excrement consists of the posphate of lime of the 
 bones, and contains scarcely ^ig part of its weight of 
 foreign organic substances. The whole process of nu- 
 trition in an animal consists in the progressive extrac- 
 tion of all the nitrogen from the food, so that the quan- 
 tity of this element found in the excrements must always 
 be less than that contained in the nutriment. The 
 analysis of the excrements of a horse by Macaire and 
 Marcet proves this fact completely. The portion of 
 excrements subjected to analysis was collected whilst 
 fresh, and dried in vacuo over sulphuric acid ; 100 parts 
 of it (corresponding to from 350 to 400 parts of the 
 dung before being dried) contained 0.8 of nitrogen. 
 Now every one who has had experience in this kind of 
 analysis is aware that a quantity under one per cent, 
 cannot be determined with accuracy. We should, 
 therefore, be estimating its proportion at a maximum, 
 were we to consider it as equal to one half per cent. 
 It is certain, however, that these excrements are not 
 entirely free from nitrogen, for they emit ammonia when 
 digested with caustic potash. 
 
 The excrements of a cow, on combustion with oxide 
 of copper, yielded a gas which contained one vol. of 
 nitrogen gas, and 26.30 vol. of carbonic acid. 
 
 100 parts of fresh excrements contained. 
 
 Nitrogen, 0.506 
 
 Carbon, 6.204 
 
 Hydrogen, 0.824 
 
 Oxygen, 4.818 
 
 Ashes, 1.748 
 
 Water, , ... . . . 85.900 
 
 100.000 
 19* 
 
222 OF MANURE. 
 
 Now, according to the analysis of Boussingault, 
 which merits the greatest confidence, hay contains one 
 per cent, of nitrogen ; consequently in the 25 lbs. of 
 hay which a cow consumes daily, | of a lb. of nitrogen 
 must have been assimilated. This quantity of nitrogen 
 entering into the composition of muscular fibre would 
 yield 8.3 lbs. of flesh in its natural condition.* The 
 daily increase in size of a cow is, however, much less 
 than this quantity. We find that the nitrogen, appar- 
 ently deficient, is actually contained in the milk and 
 urine of the animal. The urine of a milch-cow contains 
 Jess nitrogen than that of one which does not yield 
 milk ; and as long as a cow yields a plentiful supply of 
 milk, it cannot be fattened. We must search for the 
 nitrogen of the food assimilated not in the solid, but in 
 the liquid excrements. The influence which the former 
 
 * 100 lbs. of flesh contain on an average 15.86 of muscular fibre : 
 18 parts of nitrogen are contained in TOO parts of the latter. — L. 
 
 The flesh of animals when digested in repeated portions of cold 
 water, affords albumen, saline substances, and coloring and extractive 
 matters. When the part that is no longer acted on by cold water is 
 digested in hot water, the cellular substance is removed in the form 
 of selatine, and fatty matter separates. The insoluble residue is prin- 
 cipally Jibrinc. 
 
 The following is the proportion of water, albumen, and gelatine in 
 the muscular parts of several animals and fishes. 
 
 100 parts of 
 
 
 Albumen or 
 
 
 Total of 
 
 Muscle of 
 
 Water. 
 
 Fibrine. 
 
 Gelatine. 
 
 JV^utritive 
 
 Matter. 
 
 Beef, 
 
 74 
 
 20 
 
 6 
 
 
 26 
 
 Veal, 
 
 75 
 
 19 
 
 6 
 
 
 25 
 
 Mutton, 
 
 71 
 
 22 
 
 7 
 
 
 29 
 
 Pork, 
 
 76 
 
 19 
 
 5 
 
 
 24 
 
 ^Chicken, 
 
 73 
 
 20 
 
 7 
 
 
 27 
 
 Cod, 
 
 79 
 
 14 
 
 7 
 
 
 21 
 
 Haddock, 
 
 82 
 
 13 
 
 5 
 
 
 18 
 
 See Brande's Chemistry, 4th edit. p. 1184. 
 
ITS ESSENTIAL ELEMENTS. 223 
 
 exercise on the growth of vegetables does not depend 
 upon the quantity of nitrogen which they contain. For 
 if this were the case, hay should possess the same in- 
 fluence ; that is, from 20 to 25 lbs. ought to have the 
 same power as 100 lbs. of fresh cow-dung. But this 
 is quite opposed to all experience. 
 
 Which then are the substances in the excrements of 
 the cow and horse which exert an influence on vegeta- 
 tion ? 
 
 When horse's dung is treated with water, a portion 
 of it to the amount of 3 or 3| per cent, is dissolved, and 
 the water is colored yellow. The solution is found to 
 contain phosphate of magnesia, and salts of soda, be- 
 sides small quantities of organic matters. The portion 
 of the dung undissolved by the water yields to alcohol 
 a resinous substance possessing all the characters of gall 
 which has undergone some change ; while the residue 
 possesses the properties of sawdust, from which all sol- 
 uble matter has been extracted by water, and burns 
 without any smell. 100 parts of the fresh dung of a horse 
 being dried at 100° C (212° F.) leave from 25 to 30 or 
 31 parts of solid substances, and contained, accordingly, 
 from 69 to 75 parts of water. From the dried excre- 
 ments, we obtain, by incineration, variable quantities of 
 salts and earthy matters according to the nature of the 
 food which has been taken by the animal. Macaire 
 and Marcet found 27 per cent, in the dung analyzed by 
 them ; I obtained only 10 per cent, from that of a horse 
 fed with chopped straw, oats, and hay. It results then 
 that with from 3,600 to 4,000 lbs. of fresh horse's dung, 
 corresponding to 1,000 lbs. of dry dung, we place on 
 the land from 2,484 to 3,000 lbs. of water, and from 
 730 to 900 lbs. of vegetable and altered gall, and also 
 
224 OF MANURE. 
 
 from 100 to 270 lbs. of salts and other inorganic sub- 
 stances.* 
 
 The latter are evidently the substances to which our 
 attention should be directed, for they are the same which 
 formed the component parts of the hay, straw, and 
 oats, with which the horse was fed. Their principal 
 constituents are the phosphates of lime and magnesia, 
 carbonate of lime and silicate of potash ; the first three 
 of these preponderated in the corn, the latter in the 
 hay. 
 
 Thus in 1,000 lbs. of horse's dung, we present to a 
 field the inorganic substances contained in 6,000 lbs. of 
 hay, or 8,300 lbs. of oats (oats containing 3.1 per cent, 
 ashes according to De Saussure). This is sufficient 
 to supply lA crop of wheat with potash and phos- 
 phates. 
 
 * Analysis of horse dung by Dr. C. T. Jackson. — 500 grains dried 
 
 at a heat a little above that of boiling water, lost 357 grains, which 
 
 was water. 
 The dry mass, weighing 143 grains, was burned, and left 8.5 grains 
 
 of ashes, of which 4.80 grains were soluble in dilute nitric acid, and 
 
 3.20 insoluble. The ashes being analyzed, gave, — 
 Silex, . . . . . 3.2 
 
 Phosphate of lime, . . . 0.4 
 
 Carbonate of ••' . . . 1.5 
 
 Phos. magnesia and soda, . 2.9 
 
 8.0 
 
 It consists, then, of the following ingredients : 
 
 Water, 357.0 
 
 Vegetable fibre and animal matter, 135.0 
 
 Silica, 3.2 
 
 Phosphate of lime, .... 0.4 
 Carbonate of " . . . . 1.5 
 
 Phos. magnesia and soda, . . . 2.9 
 
 500.0 
 Geological and Agricultural Survey of Rhode Island, p. 205. 
 
ITS ESSENTIAL ELEMENTS. 225 
 
 The excrements of cows, black cattle, and sheep, 
 contain phosphate of lime, common salt, and silicate 
 of lime, the weight of which varies from 9 to 28 per 
 cent, according to the fodder which the animal receives ; 
 the fresh excrements of the cow contain from 86 to 90 
 per cent, of water. 
 
 Human faeces have been subjected to an exact analy- 
 sis by BerzcKus. When fresh, they contain, besides 4 
 of their weight of water, nitrogen in very variable quan- 
 tity, namely, in the minimum Ij, in the maximum 5 
 per cent. In all cases, however, they were richer 
 in this element than were the excrements of other ani- 
 mals. Bcrzelius obtained by the incineration of 100 
 parts of dried excrements, 15 parts of ashes, which 
 were principally composed of the phosphates of lime 
 and magnesia. 
 
 It is quite certain that the vegetable constituents of 
 the excrements with which we manure our fields cannot 
 be entirely without influence upon the growth of the 
 crops on them, for they will decay, and thus furnish car- 
 bonic acid to the young plants. But it cannot be im- 
 agined that their influence is very great, when it is con- 
 sidered that a good soil is manured only once every six 
 or seven years, or once every eleven or twelve years, 
 when esparsette or lucern have been raised on it, that 
 the quantity of carbon thus given to the land corresponds 
 to only 5.8 per cent, of what is removed in the form of 
 herbs, straw, and grain, and further, that the rain-water 
 received by a soil contains much more carbon in the 
 form of carbonic acid than these vegetable constituents 
 of the manure. 
 
 The peculiar action, then, of the solid excrements is 
 limited to their inorganic constituents, which thus re- 
 
226 OF MANTTRE, 
 
 Store to a soil that which is removed in the form of corn, 
 roots, or grain. When we manure land with the dung 
 of the cow or sheep, we supply it with silicate of pot- 
 ash and some salts of phosphoric acid. In human fseces 
 we give it the phosphates of lime and magnesia ; and in 
 those of the horse, phosphate of magnesia, and silicate 
 of potash. In the straw which has served as litter, we 
 add a further quantity of silicate of potash and phos- 
 phates ; which, if the straw be putrefied, are in exactly 
 the same condition in which they were before being as- 
 similated. 
 
 It is evident, therefore, that the soil of a field will al- 
 ter but little, if we collect and distribute the dung care- 
 fully ; a certain portion of the phosphates, however, 
 must be lost every year, being removed from the land 
 with the corn and cattle, and this portion will accumu- 
 late in the neighbourhood of large towns. The loss thus 
 suffered must be compensated for in a well managed 
 farm, and this is partly done by allowing the fields to lie 
 in grass. In Germany, it is considered that for every 
 100 acres of corn land, there must, in order to effect a 
 profitable cultivation, be 20 acres of pasture land, which 
 produce annually, on an average, 500 lbs. of hay. Now, 
 assuming that the ashes of the excrements of the animals 
 fed with this hay amount to G.82 per cent., then 341 
 lbs. of the silicate of lime, and phosphates of magnesia 
 and lime must be yielded by these excrements, and will 
 in a certain measure compensate for the loss which the 
 corn land had sustained. The absolute loss in the salts 
 of phosphoric acid, which are not again rej)laced, is 
 spread over so great an extent of surface, that it scarce- 
 ly deserves to be taken account of. But the loss of 
 
ITS ESSENTIAL ELEMENTS. 227 
 
 phosphates is again replaced in the pastures by the ashes 
 of the wood used in our houses for fuel. 
 
 We could keep our fields in a constant state of fer- 
 tility by replacing every year as much as we remove 
 from them in the form of produce ; but an increase of 
 fertility, and consequent increase of crop, can only be 
 obtained when we add more to them than we take away. 
 It will be found, that of two fields placed under condi- 
 tions otherwise similar, the one will be most fruitful 
 upon which the plants are enabled to appropriate more 
 easily and in greater abundance those contents of the 
 soil which are essential to their growth and development. 
 
 From the foregoing remarks it will readily be inferred, 
 that for animal excrements, other substances containing 
 their essential constituents may be substituted. In 
 Flanders, the yearly loss of the necessary matters in 
 the soil is completely restored by covering the fields 
 with ashes of wood or bones, which may or may not 
 have been lixiviated,* and of which the greatest part 
 consists of of phosphates of lime and magnesia. The 
 great importance of manuring with ashes has been long 
 recognised by agriculturists as the result of experi- 
 ence. So great a value, indeed, is attached to this ma- 
 terial in the vicinity of Marburg, and in the Wetterau,f 
 that it is transported as a manure from the distance of 18 
 or 24 miles. I Its use will be at once perceived, when it 
 
 * Lixiviation signifies the removal by water of the soluble alkaline 
 or saline matters in any earthy mixture; as from that of lime and pot- 
 ash, or from ashes to obtain a ley. 
 
 t Two well-known agiicultuial districts; the first in Hesse-Cassel, 
 the second in Hesse-Darmstadt. — Trans. 
 
 I Ashes are used with great advantage on the light siliceous soil of 
 Long Island, Connecticut, and various other places in the United 
 States. 
 
228 OF MANURE. 
 
 is considered that the ashes, after having been washed 
 with water, contain sihcate of potash exactly in the same 
 proportions as in straw (10 Si O 3 + K O), and that 
 their only other constituents are salts of phosphoric acid. 
 
 But ashes obtained from various kinds of trees are of 
 very unequal value for this purpose ; those from oak- 
 wood are the least, and those from beech the most ser- 
 viceable. The ashes of oak-wood contain only traces 
 of phosphates, those of beech the fifth part of their 
 weight, and those of the pine and fir from 9 to 15 per 
 cent. The ashes of pines from Norway contain an ex- 
 ceedingly small quantity of phosphates, namely, only 1.8 
 per cent, of phosphoric acid. (Berthier.)* 
 
 With every 100 lbs. of the lixiviated ashes of the 
 beech which we spread over a soil, we furnish as much 
 phosphates as 460 lbs. of fresh human excrements could 
 yield. Again, according to the analysis of De Saussure, 
 100 parts of the ashes of the grain of wheat contain 32 
 parts of soluble, and 44.5 of insoluble phosphates, in all 
 
 * " The existence of pliosphate of litne in the forest soils of the 
 United States, is proved not only by its existence in the pollen of the 
 pinus ubics (which is composed of 3 per cent, phosphate of lime 
 and potash), but by its actual detection in the ashes of pines and 
 other trees. — 100 parts of the ashes of wood of pinus dbies give 3 
 per cent, phosphate of iron ; 100 parts of the ashes of the coal of 
 pinus sylvestris give 1.72 phosphate of lime, 25 phosphate of iron ; 
 100 parts of ashes of oak coal give 7.1 phosphate of lime, 3.7 phos- 
 phate of iron ; 100 parts of the ashes of bass wood give 5.4 phosphate 
 of lime, 3.2 phos^jhate of iron ; 100 parts of the ashes of birch wood 
 give 7.3 pliosphate of lime, 1.25 phosphate of iron ; 100 parts of the 
 ashes of oak wood give 1.8 phosphate of lime ; 100 parts of the ashes 
 of alder coal give 3.-15 phosphate of lime, 9 phosphate of iron. These 
 are the calculated results from Certhier's analyses." — Dr. S. L. Dana 
 in Report on a Reexamination of the Economical Geology of Mas- 
 sachusetts. 
 
BONE MANURE. 229 
 
 76.5 parts. Now the ashes of wheat-straw contain 11.5 
 per cent, of the sanne salts ; hence with every 100 lbs. of 
 the ashes of the beech, we supply a field with phos- 
 phoric acid sufficient for the production of 3,820 lbs. of 
 straw (its ashes being calculated at 4.3 per cent. De 
 Saussure), or for 15-lSOOO lbs. of corn, the ashes of 
 which amount, according to De Saussure, to 1.3 per 
 cent. 
 
 Bone manure possesses a still greater importance in 
 this respect. The primary sources from which the bones 
 of animals are derived are the hay, straw, or other sub- 
 stances which they take as food. Now if we admit that 
 bones contain 55 per cent, of the phosphates of lime 
 and magnesia [Berzellus)^ and that hay contains as much 
 of them as wheat-straw, it will follow that 8 lbs. of bones 
 contain as much phosphate of lime as 1,000 lbs. of hay 
 or wheat-straw, and 2 lbs. of it as much as 1,000 lbs. of 
 the grain of wheat or oats. These numbers express 
 pretty exactly the quantity of phosphates which a soil 
 yields annually on the growth of hay and corn. Now 
 the manure of an acre of land with 40 lbs. of bone dust 
 is sufficient to supply three crops of wheat, clover, po- 
 tatoes, turnips, &c., with phosphates. But the form in 
 which they are restored lo a soil does not appear to 
 be a matter of indifference. For the more finely the 
 bones are reduced to powder, and the more intimately 
 they are mixed with a soil, the more easily are they 
 assimilated. The most easy and practical mode of ef- 
 fecting their division is to pour over the bones, in a state 
 of fine powder, half of their weight of sulphuric acid 
 diluted with three or four parts of water, and after they 
 have been digested for some time, to add one hundred 
 parts of water, and sprinkle this mixture over the field. 
 20 
 
230 OF MANURE. 
 
 before the plough. In a few seconds, the free acids unite 
 with the bases contained in the earth, and a neutral salt is 
 formed in a very fine state of division. Experiments 
 instituted on a soil formed from grauvvacke, for the pur- 
 pose of ascertaining the action of manure thus prepared, 
 have distinctly shown that neither corn, nor kitchen- 
 garden plants, suffer injurious effects in consequence, 
 but that on the contrary they thrive with much more 
 vigor. 
 
 In the manufactories of glue, many hundred tons of a 
 solution of phosphates in muriatic acid are yearly thrown 
 away as being useless. It would be important to exam- 
 ine whether this solution might not be substituted for the 
 bones. The free acid would combine with the alkalies 
 in the soil, especially with the lime, and a soluble salt 
 would thus be produced, which is known to possess a 
 favorable action upon the growth of plants. This salt, 
 muriate of lime (or chloride of calcium), is one of those 
 compounds which attracts water from the atmosphere 
 with great avidity, and might supply the place of gypsum 
 in decomposing carbonate of ammonia, with the forma- 
 tion of sal-ammoniac and carbonate of lime. A solution 
 of bones in muriatic acid placed on land in autumn or in 
 winter would, therefore, not only restore a necessary 
 constituent of the soil, and attract moisture to it, but 
 would also give it the power to retain all the ammonia 
 which fell upon it dissolved in the rain during the period 
 of six months. 
 
 The ashes of brown coal* and peat often contain sili- 
 
 * Brown coal. Braunkohlc, Lignite has the structure and appear- 
 ance of carbonized wood. It occurs abundantly in Germany ; in 
 Hessia it forms beds 20 to 40 feet thick, and several square miles in 
 
ASHES. PEAT. 231 
 
 catG of potash, so that it is evident that these might com- 
 pletely replace one of the principal constituents of the 
 dung of the cow and horse, and they contain also some 
 phosphates.* Indeed, they are much esteemed in the 
 Wetterau as manure for meadows and moist land. 
 
 extent. Fibrous and compact varieties occur near Bovey Tracey in 
 
 England, where it is called Bovey coal. Small quantities are found 
 
 at Gay Head, Massachusetts. 
 
 * The following is the result of an analysis by Dr. C. T. Jackson, 
 
 of peat from Lexington, Massachusetts. 100 grains, dried at 300° F. 
 
 weighed 74 grains, loss 26 grains, water. Buined in a platina crucible 
 
 it left 5.0 ashes. The ashes yielded 
 
 Silex, 10 
 
 Alumina, iron, and manganese, .... 0.6 
 
 Phosphate of lime, 3.0 
 
 Potash, traces. 
 
 4.6 
 
 Peat from Watertown, Massachusetts, yielded 4.5 grains of ashes, 
 
 which gave by analysis 
 
 Silex, ........ 1.3 
 
 Alumina, oxide of iron, and manganese, . . 1.5 
 
 Phosphate of lime, 1.7 
 
 4.5 
 
 The vegetable matter amounted to 95.5 per cent., consisting of 
 veo-etable fibre, and apocrenic and crenic acids, in part combined with 
 the bases obtained from its ashes. See Report on Rhode Island, 
 p. 233. 
 
 Swamp muck contains the same ingredients as peat, but the vege- 
 table matters are more finely divided, more soluble, and there is gen- 
 erally a larger proportion of earthy matters. It is formed of the fine 
 particles of humus, washed out from the upland soils, and of the dead 
 and decomposed leaves and roots of swamp plants. 
 
 The pulpy matter of both peat and swamp muck consists chiefly of 
 the apocrenic acid, in part combined with the earthy bases, and me- 
 tallic oxides. The crenic acid is frequently united with lime, man- 
 ganese ; iron and magnesia occur in several of the peats analyzed. 
 Phosjihoric acid also exists in them, both in its free state, and in com- 
 bination with lime and magnesia. In some peats Dr. J. found traces 
 of oxalic acid and oxalates. Ibid., 210. See Appendix for Peat com- 
 post. 
 
232 OF MANURE. 
 
 It is of much importance to the agriculturist, that he 
 should not deceive himself respecting the causes which 
 give the peculiar action to the substances just men- 
 tioned. It is known that they possess a very favorable 
 influence on vegetation ; and it is likewise certain, that 
 the cause of this is their containing a body, which, in- 
 dependently of the influence which it exerts by virtue of 
 its form, porosity, and capability of attracting and re- 
 taining moisture, also assists in maintaining the vital 
 processes in plants. If it be treated as an unfathoma- 
 ble mystery, the nature of this aid will never be known. 
 
 In medicine, for many centuries, the mode of actions 
 of all remedies was supposed to be concealed by the 
 mystic veil of Isis, but now these secrets have been ex- 
 plained in a very simple manner. An unpoetlcal hand 
 has pointed out the cause of the wonderful and apparent- 
 ly inexplicable healing virtues of the springs in Savoy, 
 by which the inhabitants cured their goitre ; it was 
 shown, that they contain small quantities of iodine. In 
 burnt sponges, used for the same purpose, the same ele- 
 ment was also detected. The extraordinary efficacy of 
 Peruvian bark was found to depend on the small quanti- 
 ty of a crystalline body existing in it, viz. quinine ; and 
 the causes of the various effects of opium were detect- 
 ed in as many different ingredients of that drug. 
 
 Calico printers used for a long time the solid excre- 
 ments of the cow, in order to brighten and fasten colors 
 on cotton goods ; this material appeared quite indispen- 
 sable, and its action was ascribed to a latent principle 
 which it had obtained from the living organism. But 
 since its action was known to depend on the phosphates 
 contained in it, it has been completely replaced by a 
 
PRINCIPLES OF ITS USE. 233 
 
 mixture of salts, in which the principal constituent is 
 phosphate of soda. 
 
 Now, all such actions depend on a definite cause, by 
 ascertaining which, we place the actions themselves at 
 our command. 
 
 It must be admitted as a principle of agriculture, that 
 those substances which have been removed from a soil 
 must be completely restored to it, and whether this res- 
 toration be effected by means of excrements, ashes, or 
 bones, is in a great measure a matter of indifference. 
 A time will come when fields will be manured with a 
 solution of glass* (silicate of potash), with the ashes of 
 burnt straw, and with salts of phosphoric acid, prepared 
 in chemical manufactories, exactly as at present medi- 
 cines are given for fever and goitre. 
 
 There are some plants which require humus and do not 
 restore it to the soil by their excrements ; whilst others 
 can do without it altogether, and add humus to a soil 
 which contains it in small quantity. Hence, a rational 
 system of agriculture would employ all the humus at 
 command for the supply of the former, and not expend 
 any of it for the latter ; and would in fact make use of 
 them for supplying the others with humus. 
 
 We have now considered all that is requisite in a soil, 
 in order to furnish its plants with the materials necessary 
 for the formation of the woody fibre, the grain, the roots, 
 and the stem, and now proceed to the consideration of 
 the most important object of agriculture, viz. the pro- 
 
 * When glass contains a very large proportion of potash, it is solu- 
 ble in boiling water ; and by combination with other substances, silica 
 becomes soluble in water. According to Dr. Jackson, crenic acid en- 
 ables water to take it up. 
 20* 
 
234 OF MANURE. 
 
 duction of nitrogen in a form capable of assimilation, — 
 the production, therefore, of substances containing this 
 element. The leaves, which nourish the woody matter, 
 the roots, from which the leaves are formed, and which 
 prepare the substances for entering into the composition 
 of the fruit, and, in short, every part of the organism of 
 a plant, contain azotized matter in very varying propor- 
 tions, but the seeds and roots are always particularly rich 
 in them. 
 
 Let us now examine in what manner the greatest pos- 
 sible production of substances containing nitrogen can 
 be effected. Nature, by means of the atmosphere, fur- 
 nishes nitrogen to a plant in quantity sufficient for its 
 normal growth. Now its growth must be considered as 
 normal, when it produces a single seed, capable of re- 
 producing the same plant in the following year. Such 
 a normal condition would suffice for the existence of 
 plants, and prevent their extinction, but they do not ex- 
 ist for themselves alone ; the greater number of animals 
 depend on the vegetable world for food, and by a wise 
 adjustment of nature, plants have the remarkable power 
 of converting, to a certain degree, all the nitrogen of- 
 fered to them into nutriment for animals. 
 
 We may furnish a plant with carbonic acid, and all 
 the materials which it may require, we may supply it 
 with humus in the most abundant quantity, but it will not 
 attain complete development unless nitrogen is also af- 
 forded to it ; an herb will be formed, but no grain, even 
 sugar and starch may be produced, but no gluten. 
 
 But when we give a plant nitrogen in considerable 
 quantity, we enable it to attract with greater energy, 
 from the atmosphere, the carbon which is necessary for 
 its nutrition, when that in the soil is not sufficient ; we 
 
FjECes. urine. 235 
 
 afford to it a means of fixing the carbon of the atmo- 
 sphere in its organism. 
 
 We cannot ascribe much of the power of the excre- 
 ments of black cattle, sheep, and horses, to the nitrogen 
 which they contain, for its quantity is too minute. But 
 that contained in the faeces of man is proportionably 
 much greater, although by no means constant. In the 
 faeces of the inhabitants of towns, for example, who feed 
 on animal matter, there is much more of this constituent 
 than in those of peasants, or of such people as reside in 
 the country. The faeces of those who live principally 
 on bread and potatoes are similar in composition and 
 properties to those of animals. 
 
 All excrements have in this respect a very variable 
 and relative value. Thus, those of black cattle and 
 horses, are of great use on soils consisting of lime and 
 sand, which contain no silicate of potash and phosphates, 
 whilst their value is much less when applied to soils 
 formed of argillaceous earth, basalt, granite, porphyry, 
 clinkstone, and even mountain limestone, because all 
 these contain potash in considerable quantify. In such 
 soils human excrements are extremely beneficial, and in- 
 crease their fertility in a remarkable degree ; they are, of 
 course, as advantageous for other soils also ; but for the 
 manure of those first mentioned, the excrements of 
 other animals are quite indispensable. 
 
 We possess only one other source of manure which 
 acts by its nitrogen, besides the faeces of animals, — 
 namely, the urine of man and animals. 
 
 Urine is employed as manure either in the liquid 
 state, or with the faeces which are impregnated with 
 it. It is the urine contained in them which gives to 
 the solid faeces the property of emitting ammonia, a 
 
236 
 
 OP MANURE. 
 
 property which they themselves possess only in a very 
 slight degree. 
 
 When we examine what substances we add to a soil 
 by supplying it with urine, we find that this liquid contains 
 in solution ammoniacal salts, uric acid, (a substance con- 
 taining a large quantity of nitrogen), and salts of phos- 
 phoric acid. 
 
 According to Berzdius 1000 parts of human urine 
 contain : — 
 
 Urea, 30.10 
 
 Free Lnctic acid*, Lactate of Ammonia, and ani- 
 mal matter not separable from them, . . 17.14 
 
 Uric Acid, 
 
 Mucus of the bladder, 
 Sulphate of Potash, 
 Sulphate of Soda, 
 Phosphate of Soda, 
 Phosphate of Ammonia, 
 Cliloride of Sodium, 
 Muriate of Ammonia, 
 Phosphates of Magnesia and 
 Siliceous earth, . 
 Water, . 
 
 1.00 
 0.32 
 371 
 3.16 
 2.94 
 1.65 
 4.45 
 1.50 
 1.00 
 0.03 
 933.00 
 
 1000.00 
 
 If we subtract from the above the urea, lactate of am- 
 monia, free lactic acid, uric acid, the phosphate and muri- 
 ate of ammonia, I per cent, of solid matter remains,, 
 consisting of inorganic salts, which must possess the 
 same action when brought on a field, whether they are 
 dissolved in water or in urine. Hence the powerful 
 influence of urine must depend upon its other ingredi- 
 ents, namely the urea and ammoniacal salts. The urea 
 
 * Lactic acid has been found in most animal fluids and in several 
 plants. It was first obtained from sour milk, hence its name from the 
 Latin lac, milk. 
 
AMMONIA FROM URINE. 237 
 
 in human urine exists partly as lactate of urea, and part- 
 ly in a free state. {Henry.) * Now when urine is 
 allowed to putrefy spontaneously, that is, to pass into 
 that state in which it is used as manure, all the urea in 
 combination with lactic acid is converted into lactate of 
 ammonia, and that which was free, into volatile carbonate 
 of ammonia. 
 
 In dung-reservoirs well constructed and protected 
 from evaporation, this carbonate of ammonia is retained 
 in the state of solution, and when the putrefied urine is 
 spread over the land, a part of the ammonia will escape 
 with the water which evaporates, but another portion 
 will be absorbed by the soil, if it contains either alumi- 
 na or iron ; but in general, only the muriate, phosphate, 
 and lactate of ammonia remain in the ground. It is 
 these alone, therefore, which enable the soil to exercise 
 a direct influence on plants during the progress of their 
 growth, and not a particle of them escapes being ab- 
 sorbed by the roots. 
 
 On account of the formation of this carbonate of am- 
 monia, the urine becomes alkaline, although it is acid in 
 its natural state. When it is lost by being volatilized in 
 the air, which happens in most cases, the loss suffered 
 is nearly equal to one half of the weight of the urine em- 
 •ployed, so diat if we fix it, that is, if we deprive it of its 
 volatility, we increase its action twofold. The exis- 
 tence of carbonate of ammonia in putrefied urine long 
 since suggested the manufacture of sal-ammoniac from 
 this material. When the latter salt possessed a high 
 price, this manufacture was even carried on by the far- 
 mer. For this purpose the liquid obtained from dung- 
 
 * Urea consists of nitrogen, hydrogen, carbon, and oxygen. (NH4O 
 + C,NO). 
 
238 
 
 OF MANURE. 
 
 hills was j)laced in vessels of iron, and subjected to 
 distillation ; the product of this distillation was convert- 
 ed into muriate of ammonia by the common method. 
 (Demachi/.) But it is evident that such a thoughtless 
 proceeding must be wholly relinquished, since the nitro- 
 gen of 100 lbs. of sal-ammoniac (which contains 26 
 parts of nitrogen) is equal to the quantity of nitroge 
 contained in 1200 lbs. of the grain of wheat, 1480 lbs. 
 of that of barley, or 2755 lbs. of hay. (Boussiugault.) 
 
 The carbonate of ammonia formed by the putrefac- 
 tion of urine, can be fixed or deprived of its volatility in 
 many ways. 
 
 If a field be strewed with gypsum, and then with pu- 
 trefied urine or the drainings of dunghills, all the carbon- 
 ate of ammonia will be converted into the sulphate which 
 will remain in the soil. 
 
 But there are still simpler means of effecting this 
 purpose; — gypsum, chloride of calcium, sulphuric or 
 muriatic acid, and super-phosphate of lime, are all sub- 
 stances of a very low price, and completely neutralize 
 the urine, converting its ammonia into salts which pos- 
 sess no volatility. 
 
 If a basin filled with concentrated muriatic acid is 
 placed in a common necessary, so that its surface is in 
 free communication with the vapors which rise from be-* 
 low, it becomes filled after a few days with crystals of 
 muriate of ammonia. The ammonia, the presence of 
 which the organs of smell amply testify, combines with 
 the muriatic acid and loses entirely its volatility, and 
 thick clouds or fumes of the salt newly formed hang 
 over the basin. In stables the same may be seen. The 
 ammonia that escapes in this manner, is not only entire- 
 ly lost as far as our vegetation is concerned, but it 
 
AMMONIA FROM URINE. 239 
 
 works also a slow, though not less certain destruction of 
 the walls of the building. For when in contact with the 
 lime of the mortar, it is converted into nitric acid, which 
 gradually dissolves the lime. The injury thus done to 
 a building by the formation of the soluble nitrates has 
 received (in Germany) a special name, — salpeierfrass. 
 
 The ammonia emitted from stables and necessaries is 
 always in combination with carbonic acid. Carbonate 
 of ammonia and sulphate of lime (gypsum) cannot be 
 brought together at common temperatures, without mu- 
 tual decomposition. The ammonia enters into combi- 
 nation with the sulphuric acid, and the carbonic acid 
 with the lime, forming compounds which are not vola- 
 tile, and, consequently, destitute of all smell. Now if 
 we strew the floors of our stables, from time to time, 
 with common gypsum, they will lose all their offensive 
 smell, and none of the ammonia which forms can be 
 lost, but will be retained in a condition serviceable as 
 manure. 
 
 With the exception of urea, uric acid contains more 
 nitrogen than any other substance generated by the living 
 organism ; it is soluble in water, and can be thus absorb- 
 ed by the roots of plants, and its nitrogen assimilated in 
 the form of ammonia, and of the oxalate, hydrocyanate, 
 or carbonate of ammonia. 
 
 It would be extremely interesting to study the trans- 
 formations which uric acid suffers in a living plant. For 
 the purpose of experiment, the plant should be made to 
 grow in charcoal powder previously heated to redness, 
 and then mixed with pure uric acid. The examination 
 of the juice of the plant, or of the component parts 
 of the seed or fruit, would be a means of easily detect- 
 ing the differences. 
 
240 OF MANURE. 
 
 In respect to the quantity of nitrogen contained in 
 exciements, 100 parts of the urine of a heahhy man are 
 equal to 1300 parts of the fresh dung of a horse, accord- 
 ing to the analyses of J\Iacaire and JlJarcet, and to 600 
 parts of those of a cow. Hence it is evident that it 
 would be of much importance to agriculture if none of 
 the human urine were lost. The powerful effects of 
 urine as a manure are well known in Flanders, but they 
 are considered invaluable by the Chinese, who are the 
 oldest agricultural people we know. Indeed so much 
 value is attached to the influence of human excrements 
 by these people, that laws of the state forbid that any 
 of them should be thrown away, and reservoirs are 
 placed in every house, in which they are collected with 
 the greatest care. No other kind of manure is used for 
 their corn-fields. 
 
 China is the birth-place of the experimental art ; the 
 incessant striving after experiments has conducted the 
 Chinese a thousand years since to discoveries, which 
 have been the envy and admiration of Europeans for 
 centuries, especially in regard to dyeing and painting, 
 and to the manufactures of porcelain, silk, and colors for 
 painters. These we were long unable to imitate, and 
 yet they were discovered by them without the assistance 
 of scientific principles ; for in the books of the Chinese 
 we find recipes and directions for use, but never explana- 
 tions of processes. 
 
 Half a century sufficed to Europeans, not only to 
 equal but to surpass the Chinese in the arts and manufac- 
 tures, and this was owing merely to the application of 
 correct principles deduced from the study of chemistry. 
 But how infinitely inferior is the agriculture of Europe 
 10 that of China ! The Chinese are the most admirable 
 
VALUE OF HUMAN EXCREMENTS. 241 
 
 gardeners and trainers of plants, for each of which they 
 understand how to prepare and apply the best adapted 
 manure. The agriculture of their country is the most 
 perfect in the world ; and there, where the climate in the 
 most fertile districts differs little from the European, 
 very little value is attached to the excrements of 
 animals.* With us, thick books are written, but no 
 
 * This is, however, in consequence of its scarcity. Davis, in his 
 History of China, states that every substance convertible into manure 
 is diligentlj' husbanded. " The cakes that remain after the expres- 
 sion of their vegetable oils, horns and hoofs reduced to powdefj 
 tocrether with soot and ashes, and the contents of common sewers are 
 much used. The plaster of old kitchens, which in China have na 
 chimneys, but an opening at Ihe top, is much valued : so that they 
 will sometimes put new plaster on a kitchen for the sake of the old. 
 All sorts of hair are used as manure, and barber's shavings are care- 
 fully appropriated to that purpose. The annual produce must be con- 
 siderable, in a country where some hundred millions of heads are 
 kept constantly shaved. Dung of all animals, but more especially- 
 night soil, is esteemed above all others. Being sometimes formed 
 into cakes, it is dried in the sun, and in this state becomes an object 
 of sale to farmers, who dilute it previous to use. They construct 
 large cisterns or pits lined with lime plaster, as well as earthern tubs, 
 sunk in the ground, with straw over them to prevent evaporation^ 
 in which all kinds of vegetables and animal refuse are collected. 
 These being diluted with a sufficient quantity of liquid, are left to. 
 undergo the putrefactive fermentation, and then applied to the land.'' 
 
 " In the case of every thing except rice, the Chinese seem to ma- 
 nure rather the plant itself than the soil, supplying it copiously with, 
 their liquid preparation." 
 
 "The Chinese husbandman," observes Sir G. Staunton {Embassy,. 
 Vol. II. p. 476,) " always steeps the seeds he intends to sow in liquid 
 manure, until they swell, and germination begins to appear, which,, 
 experience has taught him, will have the effect of hastening the 
 growth of plants, as well as of defending them against the insects 
 hidden in the ground in which the seeds are sown. To tlie roots 
 of plants and fruit-trees the Chinese farmer applies liquid manure- 
 likewise." 
 
 These statements are confirmed by others which have been kindly 
 
 21 
 
242 OF MANURE. 
 
 experiments inslituted ; the quantity of manure con- 
 sumed by this and that plant, is expressed in hundredth 
 parts, and yet we know not what manure is ! 
 
 If we admit that the liquid and solid excrements of 
 man amount on an average to 1| lbs. daily (| lb. urine 
 and I lb. faeces), and that both taken together contain 3 
 per cent, of nitrogen, then in one year they will amount 
 to 547 lbs., which contain 16.41 lbs. of nitrogen, a 
 quantity sufficient to yield the nitrogen of 800 lbs. of 
 wheat, rye, oats, or of 900 lbs. of barley. (^Boussin- 
 gault.) 
 
 This is much more than it is necessary to add to an 
 acre of land, in order to obtain, with the assistance of 
 the nitrogen absorbed from the atmosphere, the richest 
 possible crop every year. Every town and farm 
 might thus supply itself with the manure, which besides 
 containing the most nitrogen, contains also the most 
 phosphates ; and if an alternation of the crops were 
 adopted, they would be most abundant. By using, at 
 the same time, bones and the lixiviated ashes of wood, 
 the excrements of animals might be completely dis- 
 pensed with. 
 
 When human excrements are treated in a proper 
 manner, so as to remove the moisture which they con- 
 tain without permitting the escape of ammonia, they 
 may be put into such a form as will allow them to be 
 transported, even to great distances. 
 
 communicated to me by a gentleman whose opportunities for observa- 
 tion during a residence in Cliina of several years, were ample, and 
 wliose liberality and devotion to agriculture and horticulture have 
 already conferred upon the community results of great interest and 
 value. — See Appendix. ^ 
 
VALUE OF HUMAN EXCREMENTS. 243 
 
 This is already attempted In many towns, and the 
 preparation of human excrements for transportation con- 
 stitutes not an unimportant branch of industry. But the 
 manner in which this is done is the most injudicious 
 which could be conceived. In Paris, for example, the 
 excrements are preserved in the houses in open casks, 
 from which they are collected and placed in deep pits 
 at Montfaucon, but are not sold until they have attained 
 a certain degree of dryness by evaporation in the air. 
 But whilst lying in the receptacles appropriated for 
 them in the houses, the greatest part of their urea is 
 converted into carbonate of ammonia ; lactate and phos- 
 phate of ammonia are also formed, and the vegetable 
 matters contained in them putrefy ; all their sulphates 
 are decomposed, v/hilst their sulphur forms sulphuretted 
 hydrogen and hydro-sulphate of ammonia. The mass 
 when dried by exposure to the air has lost more than 
 half of the nitrogen which the excrements originally 
 contained ; for the ammonia escapes into the atmosphere 
 along with the water which evaporates ; and the residue 
 now consists principally of phosphate of lime, with 
 phosphate and lactate of ammonia, and small quantities 
 of urate of magnesia and fatty matter. Nevertheless it is 
 still a very powerful manure, but its value as such would 
 be twice or four times as great, if the excrements be- 
 fore being dried were neutralized with a cheap mineral 
 acid. 
 
 In other manufactories of manure, the excrements 
 whilst still soft are mixed with the ashes of wood, or 
 with earth,* both of which substances contain a large 
 
 * This is practised in the vicinity of large cities in the United 
 States. 
 
244 OF MANURE. 
 
 quantity of caustic lime, by means of which a complete 
 expulsion of all their ammonia is effected, and they are 
 completely deprived of smell. But such a residue 
 applied as manure can act only by the phosphates which 
 it still contains, for all the ammoniacal salts have been 
 decomposed, and their ammonia expelled. 
 
 The sterile soils of the South American coast are 
 manured with a substance called guano, consisting of 
 urate of ammonia, and other ammoniacal salts, by the 
 use of which a luxuriant vegetation and the richest 
 crops are obtained. The corn-fields in China receive 
 no other manure than human excrements. But we 
 cover our fields every year with the seeds of weeds, 
 which from their nature and form pass undigested along 
 with the excrements through animals, without being de- 
 prived of their power of germination, and yet it is con- 
 sidered surprising that where they have once flourished, 
 they cannot again be expelled by all our endeavours : 
 we think it very astonishing, while we really sow them 
 ourselves every year. A famous botanist, attached to 
 the Dutch embassy to China, could scarcely find a sin- 
 gle plant on the corn-fields of the Chinese, except the 
 corn itself.* 
 
 The urine of horses contains less nitrogen and phos- 
 phates than that of man. According to Fourcroy and 
 Vauquelin it contains only five per cent, of solid matter, 
 and in that quantity only 0.7 of urea ; whilst 100 parts 
 of the urine of man contain more than four times as 
 much. 
 
 The urine of a cow is particularly rich in salts of 
 potash ; but according to Rouelle and Brande, it is 
 
 * Ingenhouss on the Nutrition of Plants, page 12i) (German edition). 
 
ITS EFFECT. 245 
 
 almost destitute of salts of soda. The urine of swine 
 contains a large quantity of the phosphate of magnesia 
 and ammonia ; and hence it is that concretions of this 
 salt are so frequently found in the urinary bladders of 
 these animals. 
 
 It is evident that if we place the solid or liquid ex- 
 crements of man, or the liquid excrements of animals, 
 on our land, in equal proportion to the quantity of 
 nitrogen removed from it in the form of plants, the 
 sum of this element in the soil must increase every 
 year ; for the quantity which we thus supply, an- 
 other portion is added from the atmosphere. The ni- 
 trogen which we export as corn and cattle, and which 
 is thus absorbed by large towns, serves only to benefit 
 other farms, if we do not replace it. A farm which 
 possesses no pastures, and not fields sufficient for the 
 cultivation of fodder, requires manure containing nitro- 
 gen to be imported from elsewhere, if it is desired to 
 produce a full crop. In large farms, the annual expendi- 
 ture of nitrogen is completely replaced by means of the 
 pastures. 
 
 The only absolute loss of nitrogen, therefore, is lim- 
 ited to the quantity which man carries with him to his 
 grave ; but this at the utmost cannot amount to more than 
 3 lbs. for every individual, and is being collected during 
 his whole life. Nor is this quantity lost to plants, for it 
 escapes into the atmosphere as ammonia during the pu- 
 trefaction and decay of the body. 
 
 A high degree of culture requires an increased supply 
 of manure. With the abundance of the manure the pro- 
 duce in corn and cattle will augment, but must diminish 
 with its deficiency. 
 
 From the preceding remarks it must be evident, that 
 21* 
 
246 OF MANURE. 
 
 the greatest value should be attached to the liquid excre- 
 ments of man and animals when a manure is desired 
 which shall supply nitrogen to the soil. The greatest 
 part of" a superabundant crop, or, in other words, the in- 
 crease of growth which is in our power, can be obtained 
 exclusively by their means. 
 
 When it is considered that with every pound of am- 
 monia which evaporates, a loss of GO lbs. of corn is sus- 
 tained, and that with every pound of urine a pound of 
 wheat might be produced, the indifference with which 
 these liquid excrements are regarded is quite incompre- 
 hensible. Ill most places, only the solid excrements im- 
 pregnated with the liquid are used, and the dunghills con- 
 taining them are protected neither from evaporation nor 
 from rain. The solid excrements contain the insoluble, 
 the liquid all the soluble phosphates, and the latter con- 
 tain likewise all the potash which existed as organic salts 
 in the plants consumed by the animals. 
 
 Fresh bones, wool, hair, hoofs, and horn, are manures 
 containing nitrogen as well as phosphates, and are conse- 
 quently fit to aid the process of vegetable life. 
 
 One hundred parts of dry bones contain from 32 to 
 33 per cent, of dry gelatine ; now, supposing this to 
 contain the same quantity of nitrogen as animal glue, viz. 
 5.28 per cent., then 100 parts of bones must be con- 
 sidered as equivalent to 250 parts of human urine. 
 
 Bones may be preserved unchanged for thousands of 
 years, in dry or even in moist soils, provided the access 
 of rain is prevented, as is exemplified by the bones of 
 antediluvian animals found in loam or gypsum, the interior 
 parts being protected by the exterior from the action of 
 water. But they become warm when reduced to a fine 
 powder, and moistened bones generate heat and enter 
 
CHARCOAL, &C. 247 
 
 into putrefaction ; the gelatine which they contain is de- 
 composed, and its nitrogen converted into carbonate of 
 ammonia and other ammoniacal sahs, which are retained 
 in a great measure by the powder itself. (Bones burnt 
 till quite white, and recently heated to redness, absorb 
 7.5 times their volume of pure ammoniacal gas.) 
 
 Charcoal in a state of powder must be considered as 
 a very powerful means of promoting the growth of plants 
 on heavy soils, and particularly on such as consist of ar- 
 gillaceous earth. 
 
 Ingenhouss proposed dilute sulphuric acid as a means 
 of increasing the fertility of a soil. Now, when this acid 
 is sprinkled on calcareous soils, gypsum (sulphate of 
 lime) is immediately formed, which of course prevents 
 the necessity of manuring the soils with this material. 
 100 parts of concentrated sulphuric acid diluted with 
 from 800 to 1000 parts of water, are equivalent to 176 
 parts of gypsum. 
 
li*^'' 
 
PART SECOND. 
 
 OF THE CHEMICAL PROCESSES OF FERMENTATION, 
 DECAY, AND PUTREFACTION. 
 
 CHAPTER I. 
 
 CHEMICAL TRANSFORMATIONS. 
 
 Woody fibre, sugar, gum, and all such organic com- 
 pounds, suffer certain changes when in contact with other 
 bodies, that is, they suffer decomposition. 
 
 There are two distinct modes in which these decom- 
 positions take place in organic chemistry. 
 
 When a substance composed of two compound bodies, 
 crystallized oxalic acid * for example, is brought in con- 
 tact with concentrated sulphuric acid, a complete de- 
 composition is effected upon the application of a gentle 
 heat. Now crystallized oxalic acid is a combination of 
 water with the anhydrous acid f ; but concentrated sul- 
 phuric acid possesses a much greater affinity J for water 
 than oxalic acid, so that it attracts all the water of crys- 
 
 * An acid found in several plants, particularly of the genera oxalis, 
 rumex, &c., combined with potash, and in lichens combined with lime. 
 It is composed of carbonic acid and carbonic oxide. 
 
 1 Containing no water. t See Introduction, p. 42, 
 
250 CHEMICAL TRANSFORMATIONS. 
 
 tallization* from that substance. In consequence of this 
 abstraction of the water, anhydrous oxalic acid is set 
 free ; but as this acid cannot exist in a free state, a di- 
 vision of its constituents necessarily ensues, by which 
 carbonic acid and carbonic oxide are produced, and 
 evolved in the gaseous form in equal volumes. In this 
 example, the decomposition is the consequence of the 
 removal of two constituents (the elements of water), 
 which unite with the sulphuric acid, and its cause is the 
 superior affinity of the acting body (the sulphuric acid) 
 for water. In consequence of the removal of the com- 
 ponent parts of water, the remaining elements enter into 
 a new form ; in place of oxalic acid, we have its ele- 
 ments in the form of carbonic acid and carbonic oxide. 
 
 This form of decomposition, in which the change is 
 effected by the agency of a body which unites with one 
 or more of the constituents of a compound, is quite 
 analogous to the decomposition of inorganic substances. 
 When we bring sulphuric acid and nitrate of potash (salt- 
 petre) together, nitric acid (p. 55, note) is separated in 
 consequence of the affinity of sulphuric acid for potash ; 
 in consequence, therefore, of the formation of a new 
 compound (sulphate of potash). 
 
 In the second form of these decompositions, the 
 chemical affinity of the acting body causes the compo- 
 nent parts of the body which is decomposed to combine 
 so as to form new compounds, of which either both, or 
 only one, combine with the acting body. Let us take 
 dry wood, for example, and moisten it with sulphuric 
 acid ; after a short time the wood is carbonized, while 
 the sulphuric acid remains unchanged, with the exception 
 
 * See Introduction, p. 113. 
 
 i 
 
EXAMPLES. 251 
 
 of its being united with more water than it possessed 
 before. Now this water did not exist as such in the 
 wood, although its elements, oxygen and hydrogen, were 
 present ; but by the chemical attraction of sulphuric acid 
 for water, they were in a certain measure compelled to 
 unite in this form ; and in consequence of this, the car- 
 bon of wood was separated as charcoal. 
 
 Hydrocyanic acid,* and water, in contact with hydro- 
 chloric acid,f are mutually decomposed. The nitrogen 
 of the hydrocyanic acid, and a certain quantity of the 
 hydrogen of the water, unite together and form ammo- 
 nia ; whilst the carbon and hydrogen of the hydrocyanic 
 acid combine with the oxygen of the water, and form 
 formic acid.\. The ammonia combines with the muriatic 
 acid. Here the contact of muriatic acid with water and 
 hydrocyanic acid causes a disturbance in the attraction of 
 the elements of both compounds, in consequence of 
 whicli they arrange themselves into new combinations, 
 one of which, — ammonia, — possesses the power of 
 uniting with the acting body. 
 
 Inorganic chemistry can present instances analogous to 
 this class of decomposition also ; but there are forms of 
 organic chemical decomposition of a very different kind, 
 in which none of the component parts of the matter 
 which suffers decomposition enters into combination with 
 the body which determines the decomposition. In cases 
 of this kind a disturbance is produced in the mutual at- 
 traction of the elements of a compound, and they in con- 
 sequence arrange themselves into one or several new 
 
 * See p. 110. 
 
 t Formerly called Muriatic Acid, obtained from sea salt and com- 
 posed of Hydrogen and Chlorine. 
 t See page 127, note. 
 
252 CHEMICAL TRANSFORMATIONS. 
 
 combinations, which are incapable of suffering further 
 change under the same conditions. 
 
 When, by means of the chemical affinity of a second 
 body, by the influence of heat, or through any other 
 causes, the composition of an organic compound is made 
 to undergo such a change, that its elements form two or 
 more new compounds, this manner of decomposition is 
 called a chemical transformation or metamorphosis. It 
 is an essential character of chemical transformations, 
 that none of the elements of the body decomposed are 
 singly set at liberty. 
 
 The changes which are designated by the terms fer- 
 mentation, decay, and putrefaction, are chemical transfor- 
 mations effected by an agency which has hitherto escaped 
 attention, but the existence of which will be proved in 
 the following pages. 
 
 CHAPTER II. 
 
 ON THE CAUSES WHICH EFFECT FERMENTATION, 
 DECAY,* AND PUTREFACTION. 
 
 Attention has been recently directed to the fact, 
 that a body in the act of combination or decomposition 
 
 * An essential distinction is drawn in the following part of the work, 
 between decay and ■putrefaction {Verwesitng und Faulniss), and they 
 are shown to depend on different causes ; but as the word decay is 
 not generally applied to a distinct species of decomposition, and does 
 not indicate its true nature, I shall in future^ at the suggestion of the 
 author, employ the term ercmacausis, the meaning of which has been 
 already explained. — Trans. 
 
 I 
 
THEIR CAUSE. 253 
 
 exercises an influence upon any other body with which 
 it may be in contact. Platinum, for example, does not 
 decompose nitric acid ; it may be boiled with this acid 
 without being oxidized by it, even when in a state of 
 such fine division that it no longer reflects light (black 
 spongy platinum). But an alloy of silver and platinum 
 dissolves with great ease in nitric acid ; the oxidation 
 which the silver sufi^ers, causes the platinum to submit 
 to the same change ; or, in other words, the latter body 
 from its contact with the oxidizing silver, acquires the 
 property of decomposing nitric acid. 
 
 Copper does not decompose water, even when boiled 
 in dilute sulphuric acid, but an alloy of copper, zinc, 
 and nickel, dissolves easily in this acid with evolution 
 of hydrogen gas. 
 
 Tin decomposes nitric acid with great facility, but 
 water with difficulty : and yet, when tin is dissolved in 
 nitric acid, hydrogen is evolved at the same time, from 
 a decomposition of the water contained in the acid, and 
 ammonia is formed in addition to oxide of tin. 
 
 In the examples here given, the only combination or 
 decomposition which can be explained by chemical 
 affinity is the last. In the other cases, electrical action 
 ought to have retarded or prevented the oxidation of the 
 platinum or copper while they were in contact with sil- 
 ver or zinc, but as experience shows, the influence of 
 the opposite electrical conditions is m.ore than counter- 
 balanced by chemical actions. 
 
 The same phenomena are seen in a less dubious form 
 in compounds, the elements of which are held together 
 only by a weak affinity. It is well known that tfiere 
 are chemical compounds of so unstable a nature, that 
 changes in temperature and electrical condition, or even 
 22 
 
254 CHEMICAL TRANSFORMATIONS. 
 
 simple mechanical friction, or contact with bodies of 
 apparently totally indifferent natures, cause such a dis- 
 turbance in the attraction of their constituents, that the 
 latter enter into new forms, without any one of them 
 combining with the acting body. These compounds 
 appear to stand but just within the limits of chemical 
 combination, and agents exercise a powerful influence 
 on them, which are completely devoid of action on 
 compounds of a stronger affinity. Thus, by a slight in- 
 crease of temperature, the elements of hypochlorous 
 acid separate from one another with evolution of heat 
 and light ; chloride of nitrogen explodes by contact with 
 many bodies, which combine neither with chlorine nor 
 nitrogen at common temperatures ; and the contact of 
 any solid substance is sufficient to cause the explosion 
 of iodide of nitrogen, or fulminating silver. 
 
 It has never been supposed that the causes of the de- 
 composition of these bodies should be ascribed to a 
 peculiar power, difi'erent from that which regulates 
 chemical affinity, — a power which mere contact with 
 the down of a feather is sufficient to set in activity, and 
 which, once In action, gives rise to the decomposition. 
 These substances have always been viewed as chemical 
 combinations of a very unstable nature, in which the 
 component parts are in a state of such tension, that 
 the least disturbance overcomes their chemical affinity. 
 They exist only by the vis incrtice, and any shock or 
 movement is sufficient to destroy the attraction of (heir 
 component parts, and consequently their existence in 
 their definite form. 
 
 Peroxide of hydrogen * belongs to this class of 
 
 * A remarkable compound consislhig ol' 1 Hydrogen, and 2 Oxy- 
 gen. See description and process for obtaining in Webster's Chem- 
 istry, p. 134. 
 
THEIR CAUSE. 255 
 
 bodies ; it is decomposed by all substances capable of 
 attracting oxygen from it, and even by contact with 
 many bodies, such as platinum or silver, which do not 
 enter into combination with any of its constituents. In 
 this respect, its decomposition depends evidently upon 
 the same causes which effect that of idoide of nitrogen, 
 or fulminating silver. Yet it is singular that the cause 
 of the sudden separation of the component parts of per- 
 oxide of hydrogen has been viewed as different from 
 those of common decomposition, and has been ascribed 
 to a new power termed the catalytic force.* Now, it 
 has not been considered, that the presence of the plati- 
 num and silver serves here only to accelerate the de- 
 composition ; for without the contact of these metals, 
 the peroxide of hydrogen decomposes spontaneously, 
 although very slowly. The sudden separation of the 
 constituents of peroxide of hydrogen differs from the 
 decomposition of gaseous hypochlorous acid, or solid 
 iodide of nitrogen, only in so far as the decomposition 
 takes place in a liquid. 
 
 A remarkable action of peroxide of hydrogen has at- 
 tracted much attention, because it differs from ordinary 
 chemical phenomena. This is the reduction which 
 certain oxides suffer by contact with this substance, on 
 the instant at which the oxygen separates from the 
 water. The oxides thus easily reduced,! are those of 
 which the whole, or part at least, of their oxygen is re- 
 tained merely by a feeble affinity, such as the oxides of 
 silver and of gold, and peroxide of lead. 
 
 Now, other oxides which are very stable in composi- 
 
 * See Introduction, p. 215. 
 
 t When the oxygen is separated from a metallic oxide and the 
 metal obtained, it is said to be reduced and the process is termed 
 reduction. 
 
256 CHEMICAL TRANSFORMATIONS. 
 
 lion, effect the decomposition of peroxide of hydrogen, 
 without experiencing the smallest change ; but when 
 oxide of silver is employed to effect the decomposition, 
 all the oxygen of the silver is carried away with that 
 evolved from the peroxide of hydrogen, and as a result 
 of the decomposition, water and metallic silver remain. 
 When peroxide * of lead is used for the same purpose, 
 half its oxygen escapes as a gas. Peroxide of manga- 
 nese may in the same manner be reduced to the protox- 
 ide, and oxygen set at liberty, if an acid is at the same 
 time present, which will exercise an affinity for the pro- 
 toxide and convert it into a soluble salt. 
 
 A similar phenomenon occurs, when carbonate of sil- 
 ver is treated with several organic acids. 
 
 Now no other explanation of these phenomena can be 
 given, than that a body in the act of combination or 
 decomposition enables another body, with which it is in 
 contact, to enter into the same state. It is evident that 
 the active slate of the atoms of one body has an influence 
 upon the atoms of a body in contact with it ; and if these 
 atoms are capable of the same change as the former, 
 they likewise undergo that change ; and combinations 
 and decompositions are the consequence. But when 
 the atoms of the second body are not capable of such an 
 action, any further disposition to change ceases from the 
 moment at which the atoms of the first body assume the 
 state of rest, that is, when the changes or transformations 
 of this body are quite completed. 
 
 This influence exerted by one compound upon the 
 other, is exactly similar to that which a body in the act 
 
 * A peroxide is one that, contains the largest proportion of oxygen. 
 When several compounds of metals and oxygen occur, that which 
 contains the smallest proportion of oxygen is called the first or pro- 
 toxide. 
 
THEIR CAUSE. 257 
 
 of combustion exercises upon a combustible body in its 
 vicinity ; with this difference only, that the causes which 
 determine the participation and duration of these con- 
 ditions are different. For the cause, in the case of the 
 combustible body, is heat, which is generated every 
 moment anew ; whilst in the phenomena of decomposi- 
 tion and combination, which we are considering at pres- 
 ent, the cause is a body in the state of chemical action, 
 which exerts the decomposing influence only so long as 
 this action continues. 
 
 Numerous facts show that motion alone exercises a 
 considerable influence on chemical forces. Thus, the 
 power of cohesion does not act in many saline solutions, 
 even when they are fully saturated with salts, if ihey are 
 permitted to cool whilst at rest. In such a case, the 
 salt dissolved in a liquid does not crystallize, but when 
 a grain of sand is thrown into the solution, or when it 
 receives the slightest movement, the whole liquid be- 
 comes suddenly solid while heat is evolved. The same 
 phenomenon happens with water, for this liquid may be 
 cooled much under 82° (0° C), if kept completely 
 undisturbed, but solidifies in a moment when put in 
 motion. 
 
 The atoms of a body must in fact be set in motion 
 before they can overcome the vis inertice so as to arrange 
 themselves into certain forms. Motion, by overcoming 
 the vis inertice^ gives rise immediately to another arrange- 
 ment of the atoms of a body, that is, to the production 
 of a compound which did not before exist in it. Of 
 course these atoms must previously possess the power 
 of arranging themselves in a certain order, otherwise 
 both friction and motion would be without the smallest 
 influence. 
 
 22* 
 
258 CHEMICAL TRANSFORMATIONS. 
 
 The simple permanence in position of the atoms of a 
 body, is the reason that so many compounds appear to 
 present themselves, in conditions, and with properties, 
 different from those which they possess, when they obey 
 the natural attractions of their atoms. Thus sugar and 
 glass, when melted and cooled rapidly, are transparent, 
 of a conchoidal fracture, and elastic and flexible to a 
 certain degree. But the former becomes dull and opake 
 on keeping, and exhibits crystalline faces by cleavage, 
 which belong to crystallized sugar. Glass assumes also 
 the same condition, when kept soft by heat for a long 
 period ; it becomes white, opake, and so hard as to 
 strike fire with steel. Now, in both these bodies, the 
 compound molecules evidently have different positions 
 in the two forms. In the first form their attraction did 
 not act in the direction in which their power of cohesion 
 was strongest. It is known also, that when sulphur is 
 melted and cooled rapidly by throwing it into cold water, 
 it remains transparent, elastic, and so soft that it may be 
 drawn out into long threads; but that after a few hours 
 or days, it becomes again hard and crystalline. 
 
 The remarkable fact here is, that the amorphous sugar 
 or sulphur returns again into the crystalline condition, 
 without any assistance from an exterior cause ; a fact 
 which shows that their molecules have assumed another 
 position, and that they possess, therefore, a certain de- 
 gree of mobility, even in the condition of a solid. A 
 very rapid transposition or transformation of this kind is 
 seen in arragonite, a mineral which possesses exactly the 
 same composition as calcareous spar, but of which the 
 hardness and different crystalline form prove that its 
 molecules are arranged in a different manner. When a 
 -crystal of arragonite is heated, an interior motion of its 
 
FEEMENTATION AND PUTREFACTION. 259 
 
 molecules is caused by the expansion ; the permanence 
 of their arrangement is destroyed ; and the crystal splin- 
 ters with much violence, and falls into a heap of small 
 crystals of calcareous spar. 
 
 It is impossible for us to be deceived regarding the 
 causes of these changes. They are owing to a dis- 
 turbance of the state of equilibrium, in consequence of 
 which, the particles of the body put in motion obey other 
 afKnities or their own natural attractions. 
 
 But if it is true, as we have just shown it to be, that 
 mechanical motion is sufficient to cause a change of con- 
 dition in many bodies, it cannot be doubted that a body 
 in the act of combination or decomposition is capable 
 of imparting the same condition of motion or activity 
 in which its atoms are to certain other bodies : or in 
 other words, to enable other bodies with which it is 
 in contact to enter into combinations, or suffer decom- 
 positions. 
 
 The reality of this influence has been already suffi- 
 ciently proved by the facts derived from inorganic chem- 
 istry, but it is of much more frequent occurrence in the 
 relations of organic matters, and causes very striking and 
 vironderful phenomena. 
 
 By the terms fermentation, putrefaction, and erema- 
 causis, are meant those changes in form and properties 
 which compound organic substances undergo when sep- 
 arated from the organism, and exposed to the influence 
 of water and a certain temperature. Fermentation and 
 putrefaction are examples of that kind of decomposition 
 which we have named transformations ; the elements of 
 the bodies capable of undergoing these changes arrange 
 themselves into new combinations, in which the con- 
 stituents of water generally take a part. 
 
260 CHEMICAL TRANSFORMATIONS 
 
 Ercmacausis (or decay) differs from fermentation and 
 putrefaction, inasmuch as it cannot take place without 
 the access of air, the oxygen of which is absorbed by 
 the decaying bodies. Hence it is a process of slow 
 combustion, in which heat is uniformly evolved, and 
 occasionally even light. In the processes of decompo- 
 sition, termed fermentation and putrefaction, gaseous 
 products are very frequently formed, which are either 
 inodorous, or possess a very offensive smell. 
 
 The transformations of those matters which evolve 
 gaseous products widiout odor, are now, by pretty 
 general consent, designated by the term fermentation ; 
 whilst to the spontaneous decomposition of bodies which 
 emit gases of a disagreeable smell, the term putrefaction 
 is applied. But the smell is of course no distinctive 
 character of the nature of the decomposition, for both 
 fermentation and putrefaction are processes of decompo- 
 sition of a similar kind, the one of substances destitute 
 of nitrogen, the other of substances which contain it. 
 
 It has also been customary to distinguish from fermen- 
 tation and putrefaction a particular class of transforma- 
 tions, viz., those in which conversions and transpositions 
 are effected without the evolution of gaseous products. 
 But the conditions under which the products of the 
 decomposition present themselves are purely accidental ; 
 there is therefore no reason for the distinction just 
 mentioned. 
 
OF ORGANIC COMPOUNDS. 261 
 
 CHAPTER III. 
 
 FERMENTATION AND PUTREFACTION. 
 
 Several bodies appear to enter spontaneously into the 
 states of fermentation and putrefaction, particularly such 
 as contain nitrogen or azotized substances. Now, it is 
 very remarkable, that very small quantities of these sub- 
 stances, in a state of fermentation- or putrefaction, possess 
 the power of causing unlimited quantities of similar mat- 
 ters to pass into the same state. Thus, a small quantity 
 of the juice of grapes in the act of fermentation, added 
 to a large quantity of the same fluid, which does not 
 ferment, induces the state of fermentation in the whole 
 mass. So likewise the most minute portion of milk, 
 paste, juice of the beet-root, flesh, or blood, in the state 
 of putrefaction, causes fresh milk, paste, juice of the 
 beet-root, flesh, or blood, to pass into the same condi- 
 tion when in contact with them. 
 
 These changes evidently differ from the class of com- 
 mon decompositions which are effected by chemical af- 
 finity ; they are chemical actions, conversions, or de- 
 compositions, excited by contact with bodies already in 
 the same condition. In order to form a clear idea of 
 these processes, analogous and less complicated phe- 
 nomena must previously be studied. 
 
 The compound nature of the molecules of an organic 
 body, and the phenomena presented by them when in 
 relation with other matters, point out the true cause of 
 these transformations. Evidence is afforded even by 
 simple bodies, that in the formation of combinations, the 
 force with which the combining elements adhere to one 
 
262 CHEMICAL TRANSFORMATIONS 
 
 another is inversely proportional to the number of simple 
 atoms in the compound molecule. 
 
 There are many facts which prove, that the most 
 simple inorganic compounds are also the most stable, 
 and undergo decomposition with the greatest difficulty, 
 whilst those which are of a complex composition yield 
 easily to changes and decompositions. The cause of 
 this evidently is, that in proportion to the number of 
 atoms which enter into a compound, the directions in 
 which their attractions act will be more numerous. 
 
 Whatever ideas we may entertain regarding matter in 
 general, the existence of chemical proportions removes 
 every doubt respecting the presence of certain limited 
 groups or masses of matter which we have not the power 
 of dividing. The particles of matter called equivalents 
 in chemistry are not infinitely small, for they possess a 
 weight, and are capable of arranging themselves in the 
 most various ways, and of thus forming innumerable com- 
 pound atoms. The properties of these compound atoms 
 differ in organic nature, not only according to the form, 
 but also in many instances according to the direction and 
 place, which the simple atoms take in the compound 
 molecules. 
 
 When we compare the composition of organic com- 
 pounds with inorganic, we are quite amazed at the ex- 
 istence of combinations, in one single molecule of which, 
 ninety or several hundred atoms or equivalents are united. 
 Thus, the compound atom of an organic acid of very 
 simple composition, acetic acid for example, contains 
 twelve equivalents of simple elements ; one atom of 
 kinovic acid contains 33, 1 of sugar 36, 1 of amygdalin 
 90, and 1 of stearic acid 138 equivalents. The compo- 
 nent parts of animal bodies are infinitely more complex 
 even than these. 
 
OP ORGANIC COMPOUNDS. 263 
 
 Inorganic compounds differ from organic in as great a 
 degree in their other characters as in their simplicity of 
 constitution. Thus, the decomposition of a compound 
 atom of sulphate of potash is aided by numerous causes, 
 such as the power of cohesion, or the capability of its 
 constituents to form solid, insoluble, or at certain tem- 
 peratures volatile compounds with the body brought into 
 contact with it, and nevertheless a vast number of other 
 substances produce in it not the slightest change. Now, 
 in the decomposition of a complex organic atom, there is 
 nothing similar to this. 
 
 The empirical formula of sulphate of potash is SKO4.* 
 It contains only 1 eq. of sulphur, and 1 eq. of potassium. 
 We may suppose the oxygen to be differently distributed 
 in the compound, and by a decomposition we may re- 
 move a part or all of it, or replace one of the constitu- 
 ents of ihe compound by another substance. But we 
 cannot produce a different arrangement of the atoms, 
 because they are already disposed in the simplest form in 
 which it is possible for them to combine. Now, let us 
 compare the composition of sugar of grapes with the 
 above : here 12 eq. of carbon, 12 eq. of hydrogen, and 
 12 eq. of oxygen, are united together, and we know 
 that they are capable of combining with each other in 
 the most various ways. From the formula of sugar, we 
 might consider it either as a hydrate of carbon, wood, 
 starch, or sugar of milk, or further, as a compound of 
 either with alcohol or of formic acid with sachulmin. f 
 Indeed we may calculate almost all the known organic 
 
 * S denotes sulphur, K (Kali) potash, O oxygen, 4 the nun)ber of 
 atoms. When no number is used, one atom is understood. 
 
 I The black precipitate obtained by the action of hydrochloric acid 
 on sugar. 
 
264 CHEMICAL TRANSFORMATIONS 
 
 compounds containing no nitrogen from sugar, by simply- 
 adding the elements of water, or by replacing any one of 
 its elementary constituents by a different substance. The 
 elements necessary to form these compounds are there- 
 fore contained in the sugar, and they must also possess 
 the power of forming numerous combinations amongst 
 themselves by their mutual attractions. 
 
 Now, when we examine what changes sugar undergoes 
 when brought into contact with other bodies which exer- 
 cise a marked influence upon it, we find, that these 
 changes are not confined to any narrow Hmits, like those 
 of inorganic bodies, but are in fact unlimited. 
 
 The elements of sugar yield to every attraction, and 
 to each in a peculiar manner. In inorganic compounds, 
 an acid acts upon a particular constituent of the body, 
 which it decomposes, by virtue of its affinity for that 
 constituent, and never resigns its proper chemical char- 
 acter, in whatever form it may be applied. But when it 
 acts upon sugar, and induces great changes in it, it does 
 this, not by its superior affinity for a base existing in the 
 sugar, but by disturbing the equilibrium in the mutual 
 attraction of the elements of the sugar amongst them- 
 selves. Muriatic and sulphuric acids, which differ so 
 much from one another both in characters and composi- 
 tion, act in the same manner upon sugar. But the action 
 of both varies according to the state in which they are ; 
 thus they act in one way when dilute, in another when 
 concentrated, and even difi^erences in their temperature 
 cause a change in their action. Thus sulphuric acid of 
 a moderate degree of concentration converts sugar into 
 a black carbonaceous matter, forming at the same time 
 acetic and formic acids. But when the acid is more 
 diluted, the sugar is converted into two brown substances, 
 
OF ORGANIC COMPOUNDS. 265 
 
 both of ihem containing carbon and the elements of 
 water. Again, when sugar is subjected to the action of 
 alkahes, a whole series of different new products are ob- 
 tained, while oxidizing agents, such as nitric acid, pro- 
 duce from it carbonic acid, acetic acid, oxalic acid, 
 formic acid, and many other products which have not 
 yet been examined. 
 
 If from the facts here stated we estimate the power 
 with which the elements of sugar are united together, 
 and judge of the force of their attraction by the resist- 
 ance which they offer to the action of bodies brought 
 into contact with them, we must regard the atom of sugar 
 as belonging to that class of compound atoms, which ex- 
 ist only by the vis inertice. of their elements. Its ele- 
 ments seem merely to retain passively the position and 
 condition in which they had been placed, for we do not 
 observe that they resist a change of this condition by 
 their own mutual attraction, as is the case with sulphate 
 of potash. 
 
 Now it is only such combinations as sugar, combina- 
 tions therefore which possess a very complex molecule, 
 which are capable of undergoing the decompositions 
 named fermentation and putrefaction. 
 
 We have seen that metals acquire a power which they 
 do not of themselves possess, namely, that of decom- 
 posing water and nitric acid, by simple contact with other 
 metals in the act of chemical combination. We have 
 also seen, that peroxide of hydrogen and the persulphuret 
 of the same element, in the act of decomposition, cause 
 other compounds of a similar kind, but of which the 
 elements are much more strongly combined, to undergo 
 the same decomposition, although they exert no chemical 
 affinity or attraction for them or their constituents. The 
 23 
 
266 CHEMICAL TRANSFORMATIONS 
 
 cause which produces these phenomena will be also re- 
 cognised, by attentive observation, in those matters which 
 excite fermentation or putrefaction. All bodies in the 
 act of combination or decomposition have the property 
 of inducing those processes ; or, in other words, of caus- 
 ing a disturbance of the statical equilibrium in the attrac- 
 tions of the elements of complex organic molecules, in 
 consequence of which those elements group themselves 
 anew, according to their special affinities. 
 
 The proofs of the existence of this cause of action 
 can be easily produced ; they are found in the characters 
 of the bodies which effect fermentation and putrefaction, 
 and in the regularity with which the distribution of the 
 elements takes place in the subsequent transformations. 
 This regularity depends exclusively on the unequal affini- 
 ty which they possess for each other in an isolated con- 
 dition. The action of water on wood, charcoal, and 
 cyanogen, the simplest of the compounds of nitrogen, 
 suffices to illustrate the whole of the transformations of 
 organic bodies ; of those in which nitrogen is a constitu- 
 ent, and of those in which it is absent. 
 
 CHAPTER IV. 
 
 ON THE TRANSFORMATION OF BODIES WHICH DO 
 NOT CONTAIN NITROGEN AS A CONSTITUENT, AND 
 OF THOSE IN WHICH IT IS PRESENT. 
 
 When oxygen and hydrogen, combined in equal equiv- 
 alents, as in steam, are conducted over charcoal, heated 
 to the temperature at which it possesses the power to 
 
OF BODIES DESTITUTE OF NITROGEN. 267 
 
 enter into combination with one of these elements, a 
 decomposition of the steam ensues. An oxide of car- 
 bon (either carbonic oxide or carbonic acid) is under all 
 circumstances formed, while the hydrogen of the water 
 is liberated, or, if the temperature be sufficient, unites 
 with the carbon forming carburetted hydrogen. Accord- 
 ingly, the carbon is shared between the elements of the 
 water, the oxygen and hydrogen. Now a participation 
 of this kind, but even more complete, is observed in 
 every transformation, whatever be the nature of the 
 causes by which it is effected. 
 
 Acetic and meconic* acids suffer a true transforma- 
 tion under the influence of heat, that is, their component 
 elements are disunited, and form new compounds without 
 any of them being singly disengaged. 
 
 In these cases the carbon of the bodies decomposed 
 is shared between the oxygen and hydrogen ; part of it 
 unites with the oxygen and forms carbonic acid, whilst 
 the other portion enters into combination with the hydro- 
 gen, and an oxide of a carbohydrogen is formed, in which 
 all the hydrogen is contained. 
 
 In a similar manner, when alcohol is exposed to a 
 gentle red heat, its carbon is shared between the elements 
 of the water, — an oxide of a carbohydrogen which con- 
 tains all the oxygen, and some gaseous compounds of 
 carbon and hydrogen being produced. 
 
 It is evident that during transformations caused by heat, 
 no foreign affinities can be in play, so that the new com- 
 pounds must result merely from the elements arranging 
 themselves, according to the degree of their mutual affini- 
 ties, into new combinations which are constant and un- 
 
 * An acid existing in opium, and named from the Greek for poppy. 
 
268 CHEMICAL TRANSFORMATIONS 
 
 changeable in the conditions under which they were origi- 
 nally formed, but undergo changes when these conditions 
 become different. If we compare the products of two 
 bodies, similar in composition but different in properties, 
 which are subjected to transformations by two different 
 causes, we find that the manner in which the atoms are 
 transposed, is absolutely the same in both. 
 
 In the transformation of wood in marshy soils, by what 
 we call putrefaction, its carbon is shared between the 
 oxygen and hydrogen of its own substance, and of the 
 water, — carburetted hydrogen is consequently evolved, 
 as well as carbonic acid, both of which compounds have 
 an analogous composition (CH2, C02).* 
 
 Thus also in that transformation of sugar, which is 
 called fermentation, its elements are divided into two 
 portions ; the one, carbonic acid, which contains f of the 
 oxygen of sugar ; and the other, alcohol, which contains 
 all its hydrogen. 
 
 In the transformation of acetic acid produced by a red 
 heat, carbonic acid which contains | of the oxygen of 
 the acetic acid is formed, and acetone which contains all 
 its hydrogen. 
 
 It is evident from these facts, that the elements of a 
 complex compound are left to their special attractions 
 whenever their equilibrium is disturbed, from whatever 
 cause this disturbance may proceed. It appears also, 
 that the subsequent distribution of the elements, so as to 
 form new combinations, always takes place in the same 
 way, with this difference only, that the nature of the 
 products formed is dependent upon the number of atoms 
 of the elements which enter into action ; or in oiher 
 
 * C carbon, H hydrogen, O oxygen. 
 
OF BODIES CONTAINING NITROGEN. 269 
 
 words, that the products differ ad infinitum^ according 
 to the composition of the original substance. 
 
 Transformation of Bodies containing Nitrogen. 
 
 When those substances are examined which are most 
 prone to fermentation and putrefaction, it is found that 
 they are all, without exception, bodies which contain 
 nitrogen. In many of these compounds, a transposition 
 of their elements occurs spontaneously as soon as they 
 cease to form part of a living organism ; that is, when 
 they are drawn out of the sphere of attraction in which 
 alone they are able to exist. 
 
 There are, indeed, bodies destitute of nitrogen, which 
 possess a certain degree of stability only when in com- 
 bination, but which are unknown in an isolated condi- 
 tion, because their elements, freed from the power by 
 which they were held together, arrange themselves ac- 
 cording to their own natural attractions. 
 
 The case is very different with azotized bodies. It 
 would appear that there is some peculiarity in the nature 
 of nitrogen, which gives its compounds the power to 
 decompose spontaneously with so much facility. Now, 
 nitrogen is known to be the most indifferent of all the 
 elements ; it evinces no particular attraction to any one 
 of the simple bodies, and this character it preserves in 
 all its combinations, a character which explains the 
 cause of its easy separation from the matters vi^ith which 
 it is united. 
 
 It is only when the quantity of nitrogen exceeds a 
 certain limit, that azotized compounds have some degree 
 of permanence. Their liability to change is also dimin- 
 ished, when the quantity of nitrogen is very small in pro- 
 23* 
 
270 CHEMICAL TRANSFORMATIONS 
 
 portion to that of the other elements with which it is 
 united, so that their mutual attractions preponderate. 
 
 This easy transposition of atoms is best seen in the 
 fulminating silvers, in fulminating mercury, in the iodide 
 or chloride of nitrogen, and in all fulminating com- 
 pounds. 
 
 All other azotized substances acquire the same power 
 of decomposition, when the elements of water are 
 brought into play, and indeed, the greater part of them 
 are not capable of transformation, while this necessary 
 condition to the transposition of their atoms is absent. 
 Even the compounds of nitrogen, which are most liable 
 to change, such as those which are found in animal bod- 
 ies, do not enter into a state of putrefaction when dry. 
 
 The result of the known transformations of azotized 
 substances proves, that the water does not merely act as 
 a medium in which motion is permitted to the elements 
 in the act of transposition, but that its influence depends 
 on chemical affinity. When the decomposition of such 
 substances is effected with the assistance of water, their 
 nitrogen is invariably liberated in the form of ammonia. 
 This is a fixed rule without any exceptions, whatever may 
 be the cause which produces the decompositions. All 
 organic compounds containing nitrogen, evolve the whole 
 of that element in the form of ammonia when acted upon 
 by alkalies. Acids, and increase of temperature, pro- 
 duce the same effect. It is only when there is a defi- 
 ciency of water or its elements, that cyanogen or other 
 azotized compounds are produced. 
 
 From these facts it may be concluded, that ammonia 
 is the most stable compound of nitrogen ; and that hy- 
 drogen and nitrogen possess a degree of affinity for each 
 
OF BODIES CONTAINING NITROGEN. 271 
 
 Other, which surpasses the attraction of the latter body 
 for any other element. 
 
 Already in considering the transformations of sub- 
 stances containing no nitrogen, we have seen that a 
 powerful cause effecting the disunion of the elements of 
 a complex organic atom in a definite manner, is the 
 great affinity which carbon possesses for oxygen. But 
 carbon is also invariably contained in azotized com- 
 pounds, while the great affinity of nitrogen for hydrogen 
 furnishes a new and powerful cause, facilitating the 
 transposition of their component parts. Thus, in the 
 bodies which do not contain nitrogen we have one ele- 
 ment, and in those in which that substance is present, 
 two elements, which mutually share the elements of 
 water. Hence there are two opposite affinities at play, 
 which strengthen mutually each other's action. 
 
 Now we know, that the most powerful attractions 
 may be overcome by the influence of two affinities. 
 Thus, a decomposition of alumina may be effected with 
 the greatest facility, when the affinity of charcoal for 
 oxygen, and of chlorine for aluminum, are both put in 
 action, although neither of these alone has any influence 
 upon it. There is in the nature and constitution of the 
 compounds of nitrogen a kind of tension of their com- 
 ponent parts, and a strong disposition to yield to trans- 
 formations, which effect spontaneously the transposition 
 of their atoms on the instant that water or its elements 
 are brought in contact with them. 
 
 The characters of the hydrated cyanic acid, one of 
 the simplest of all the compounds of nitrogen, are per- 
 haps the best adapted to convey a distinct idea of the 
 manner in which the atoms are disposed of in transfor- 
 mations. This acid contains nitrogen, hydrogen, and 
 
272 CHEMICAL TRANSF*0RMAtiON9 
 
 Oxygen, in such proportions, that the addition of a cer- 
 tain quantity of the elements of water is exactly suffi- 
 cient to cause the oxygen contained in the water and 
 acid to unite with the carbon and form carbonic acid, 
 and the hydrogen of the water to combine with the 
 nitrogen and form ammonia. The most favorable con- 
 ditions for a complete transformation are, therefore, 
 associated in these bodies, and it is well known, that 
 the disunion takes place on the instant that the cyanic 
 acid and water are brought into contact, the mixture 
 being converted into carbonic acid and ammonia, with 
 brisk effervescence. 
 
 This decomposition may be considered as the type 
 of the transformations of all azotized compounds ; it is 
 putrefaction in its simplest and most perfect form, be- 
 cause the new products, the carbonic acid and ammonia, 
 are incapable of further transformations. 
 
 Putrefaction assumes a totally different and much 
 more complicated form, when the products, which are 
 first formed, undergo a further change. In these cases 
 the process consists of several stages, of which it is 
 impossible to determine when one ceases and the other 
 begins. 
 
 The transformations of cyanogen, a body composed 
 of carbon and nitrogen, and the simplest of all the com- 
 pounds of nitrogen, will convey a clear idea of the great 
 variety of products which are produced in such a case : 
 it is the only example of the putrefaction of an azotized 
 body which has been at all accurately studied. 
 
 A solution of cyanogen in water becomes turbid after 
 a short time, and deposits a black, or broivnish black 
 matter^ which is a combination of ammonia with another 
 body, produced by the simple union of cyanogen with 
 
OF BODIES CONTAINING NITROGEN. 273 
 
 water. This substance is insoluble in water, and is thus 
 enabled to resist further change. 
 
 A second transformation is effected by the cyanogen 
 being shared between the elements of the water, in con- 
 sequence of which cyanic acid is formed by a certain 
 quantity of the cyanogen combining with the oxygen of 
 the water, while hydrocyanic acid is also formed by 
 another portion of the cyanogen uniting with the hydro- 
 gen which was liberated. 
 
 Cyanogen experiences a third transformation, by 
 which a complete disunion of its elements takes place, 
 these being divided between the constituents of the 
 water. Oxalic acid is the one product of this disunion, 
 and ammonia the other. 
 
 Cyanic acid, the formation of which has been men- 
 tioned above, cannot exist in contact with water, being 
 decomposed immediately into carbonic acid and ammo- 
 nia. The cyanic acid, however, newly formed in the 
 decomposition of cyanogen, escapes this decomposition 
 by entering into combination with the free ammonia, by 
 which urea * is produced. 
 
 The hydrocyanic acid is also decomposed into a 
 brown matter which contains hydrogen and cyanogen, 
 the latter in greater proportion than it does in the gas- 
 eous state. Oxalic acid, urea, and carbonic acid, are 
 also formed by its decomposition, and formic acid and 
 ammonia are produced by the decomposition of its 
 radical. 
 
 Thus, a substance into the composition of which only 
 two elements (carbon and nitrogen) enter, yields eight 
 totally different products. Several of these products 
 
 * See page 237, note. 
 
274 CHEMICAL TRANSFORMATIONS. 
 
 are formed by the transformation of the original body, 
 its elements being shared between the constituents of 
 water ; others are produced in consequence of a further 
 disunion of those first formed. The urea and carbonate 
 of ammonia are generated by the combination of two 
 of the products, and in their formation the whole of the 
 elements have assisted. 
 
 These examples show, that the results of decompo- 
 sition by fermentation or putrefaction comprehend very 
 different phenomena. The first kind of transformation 
 is, the transposition of the elements of one complex 
 compound, by which new compounds are produced 
 with or without the assistance of the elements of water. 
 In the products newly formed in this manner, either the 
 same proportions of those component parts which were 
 contained in the matter before transformation, are found, 
 or with them, an excess, consisting of the constituents 
 of water which had assisted in promoting the disunion 
 of the elements. 
 
 The second kind of transformation consists of the 
 transpositions of the atoms of two or more complex 
 compounds, by which the elements of both arrange 
 themselves mutually into new products, with or without 
 the cooperation of the elements of water. In this kind 
 of transformations, the new products contain the sum of 
 the constituents of all the compounds which had taken 
 a part in the decomposition. 
 
 The first of these two modes of decomposition is 
 that designated fermentation^ the second putrefaction ; 
 and when these terms are used in the following pages, 
 it will always be to distinguish the two processes above 
 described, which are so different in their results. 
 
FERMENTATION OF SUGAR. 275 
 
 CHAPTER V. 
 
 FERMENTATION OF SUGAR. 
 
 The peculiar decomposition which sugar suffers may 
 be viewed as a type of all the transformations desig- 
 nated fermentation.* 
 
 Thiinard obtained from 100 grammes f of cane-sugar 
 0.5262 of absolute alcohol. 100 parts of sugar from 
 the cane yield 103.89 parts of carbonic acid and alco- 
 hol. The entire carbon in these products is equal to 
 42 parts, which is exactly the quantity originally con- 
 tained in the sugar. 
 
 The analysis of sugar from the cane, proves that it 
 contains the elements of carbonic acid and alcohol, 
 minus 1 atom of water. The alcohol and carbonic acid 
 produced by the fermentation of a certain quantity of 
 sugar, contain together one equivalent of oxygen, and 
 one equivalent of hydrogen, the elements, therefore, of 
 one equivalent of water, more than the sugar con- 
 tained. The excess of weight in the products is owing 
 to the elements of water having taken part in the meta- 
 morphosis of the sugar. 
 
 It is known that I atom of sugar contains 12 equiva- 
 lents of carbon, both from the proportions in which it 
 unites with bases, and from the composition of sac- 
 charic acid the product of its oxidation. Now none of 
 these atoms of carbon are contained in the sugar as car- 
 bonic acid, because the whole quantity is obtained as 
 oxalic acid, when sugar is treated with hypermanganate 
 
 * See illustration in Appendix. 
 
 t The gramme equals 15-4440 grains. 
 
276 FERMENTATION OF SUGAR. 
 
 of potash (^Gregory) ; and as oxalic acid is a lower 
 degree of the oxidation of carbon than carbonic acid, it 
 is impossible to conceive that the lower degree should 
 be produced from the higher, by means of one of the 
 most powerful agents of oxidation which we possess. 
 
 It can be also proved, that the hydrogen of the sugar 
 does not exist in it in the form of alcohol, for it is con- 
 verted into water and a kind of carbonaceous matter, 
 when treated with acids, particularly with such as con- 
 tain no oxygen ; and this manner of decomposition is 
 never suffered by a compound of alcohol. 
 
 Sugar contains, therefore, neither alcohol nor car- 
 bonic acid, so that these bodies must be produced by 
 a different arrangement of its atoms, and by their union 
 with the elements of water. 
 
 In the metamorphosis of the sugar (by the aid of 
 yeast), the elements of the yeast, by contact with which 
 its fermentation was effected, take no appreciable part in 
 the transposition of the elements of the sugar ; for in 
 the products resulting from the action, we find no com- 
 ponent part of this substance. 
 
 We may now study the fermentation of a vegetable 
 juice, which contains not only saccharine matter, but 
 also such substances as albumen and gluten. The juices 
 of parsnips, beet-roots, and onions, are well adapted for 
 this purpose. When such a juice is mixed with yeast 
 at comnioa temperatures, it ferments like a solution of 
 sugar. Carbonic acid gas escapes from it with effer- 
 vescence, and in the liquid, alcohol is found in quantity 
 exactly corresponding to that of the sugar originally 
 contained in the juice. But such a juice undergoes 
 spontaneous decomposition at a temperature of from 
 95° to 104° (35° — 40°C.). Gases possessing an 
 
YEAST, OR FERMENT. 277 
 
 offensive smell are evolved in considerable quantity, 
 and when the liquor is examined after the decomposi- 
 tion is completed, no alcohol can be detected. The 
 sugar has also disappeared, and with it all the azotized 
 compounds which existed in the juice previously to its 
 fermentation. Both were decomposed at the same 
 time ; the nitrogen of the azotized compounds remains 
 in the liquid as ammonia, and, in addition to it, there 
 are three new products, formed from the component 
 parts of the juice. One of these is lactic acid, the 
 slightly volatile compound found in the animal organ- 
 ism ; the other is the crystalline body which forms the 
 principal constituent of manna ; and the third is a mass 
 resembling gum-arabic, which forms a thick viscous 
 solution with water. These three products weigh more 
 than the sugar contained in the juice, even without cal- 
 culating the weight of the gaseous products. Hence 
 they are not produced from the elements of the sugar 
 alone. None of these three substances could be de- 
 tected in the juice before fermentation. They must, 
 therefore, have been formed by the interchange of the 
 elements of the sugar with those of the foreign sub- 
 stances also present. It is this mixed transformation of 
 two or more compounds which receives the special name 
 of futref action. 
 
 Yeast., or Ferment. When attention is directed to the 
 condition of those substances which possess the power 
 of inducing fermentation and putrefaction in other bod- 
 ies, evidences are found in their general characters, 
 and in the manner in which they combine, that they all 
 are bodies, the atoms of which are in the act of transpo- 
 sition. 
 
 The characters of the remarkable matter which is de- 
 24 
 
278 YEAST, OR FERMENT. 
 
 posited in an insoluble state during the fermentation of 
 beer, wine, and vegetable juices, may be first studied. 
 
 This substance, which has been called yeast or fer- 
 ment^ from the power which it possesses of causing fer- 
 mentation in sugar, or saccharine vegetable juices, pos- 
 sesses all the characters of a compound of nitrogen in 
 the state of putrefaction and ertmacausis. 
 
 Like wood in the state of eremacausis, yeast converts 
 the oxygen of the surrounding air into carbonic acid, 
 but it also evolves this gas from its own mass, like bod- 
 ies in the state of putrefaction (Colin). When kept 
 under water, it emits carbonic acid, accompanied by 
 gases of an offensive smell (Theiiard), and is at last con- 
 verted into a substance resembling old cheese (Proust). 
 But when its own putrefaction is completed, it has no 
 longer the power of inducing fermentation in other bod- 
 ies. The presence of water is quite necessary for sus- 
 taining the properties of ferment, for by simple pressure 
 its power to excite fermentation is much diminished, 
 and is completely destroyed by drying. Its action is 
 arrested also by the temperature of boiling water, by al- 
 cohol, common salt, an excess of sugar, oxide of mer- 
 cury, corrosive sublimate, pyroligneous acid, sulphurous 
 acid, nitrate of silver, volatile oils, and in short by all 
 antiseptic substances. 
 
 The insoluble part of the substance called ferment 
 does not cause fermentation. For when the yeast from 
 wine or beer is carefully washed with water, care being 
 taken that it is always covered with this fluid, the resi- 
 due does not producefe rmentation. 
 
 The soluble part of ferment likewise does not excite 
 fermentation. An aqueous infusion of ysast may be 
 mixed with a solution of sugar, and preserved in vessels 
 
ITS PROPERTIES. 279 
 
 from which the air is excluded, without either experi- 
 encing the slightest change. What then, we may ask, 
 is the matter in ferment which excites fermentation, if 
 neither the soluble nor insoluble parts possess the pow- 
 er ? This question has been answered by Colin in the 
 most satisfactory manner. He has shown that in reality 
 it is the soluble part. But before it obtains this power, 
 the decanted infusion must be allowed to cool in contact 
 with the air, and to remain some time exposed to its ac- 
 tion. When introduced into a solution of sugar in this 
 state, it produces a brisk fermentation ; but without 
 previous exposure to the air, it manifests no such prop- 
 erty. 
 
 The infusion absorbs oxygen during its exposure to 
 the air, and carbonic acid may be found in it after a short 
 time. 
 
 Yeast produces fermentation in consequence of the 
 progressive decomposition which it suffers from the ac- 
 tion of air and water. 
 
 Now, when yeast is made to act on sugar, it is found, 
 that after the transformation of the latter substance 
 into carbonic acid and alcohol is completed, part of the 
 yeast itself has disappeared. 
 
 From 20 parts of fresh yeast from beer, and 100 parts 
 of sugar, Thenard obtained, after the fermentation was 
 completed, 13.7 parts of an insoluble residue, which di- 
 minished to 10 parts when employed in the same way 
 with a fresh portion of sugar. These ten parts were 
 white, possessed of the properties of woody fibre, and 
 had no further action on sugar. 
 
 It is evident, therefore, that during the fermentation 
 of sugar by yeast, both of these substances suffer decom- 
 position at the same time, and disappear in consequence. 
 
2S0 YEAST, OR FEKMENT. 
 
 But if yeast be a body which excites fermentation by 
 being itself in a state of decomposition, all other matters 
 in the same condition should have a similar action upon 
 sugar ; and this is in reality the case. Muscle, urine, 
 isinglass, osmazome,* albumen, cheese, gliadine, gluten, 
 legumin, and blood, when in a state of putrefaction, 
 have all the power of producing the putrefaction, or fer- 
 mentation of a solution of sugar. Yeast, which by con- 
 tinued washing, has entirely lost the property of inducing 
 fermentation, regains it when its putrefaction has recom- 
 menced, in consequence of its being kept in a warm sit- 
 uation for some time. 
 
 Yeast and putrefying animal and vegetable matters act 
 as peroxide of hydrogen does on oxide of silver, when 
 they, induce bodies with which they are in contact to en- 
 ter into the same state of decomposition. The dis- 
 turbance in the attraction of the constituents of the 
 peroxide of hydrogen effects a disturbance in the attrac- 
 tions of the elements of the oxide of silver, the one 
 being decomposed, on account of the decomposition of 
 the other. 
 
 Now if we consider the process of the fermentation 
 of pure sugar, in a j)ractical point of view, we meet with 
 two facts of constant occurrence. When the quantity 
 of ferment is too small in proportion to that of the sugar, 
 its putrefaction will be completed before the transforma- 
 tion of all the sugar is effected. Some sugar here re- 
 mains undecomposed, because the cause of its transfor- 
 mation is absent, viz. contact with a body in a state of 
 decomposition. 
 
 * An extractive animal matter on which the peculiar flavor of broth 
 is supposed to depend, hence its name, from the Greek for odor and 
 broth. 
 
ITS MODE OF ACTION. 281 
 
 But when the quantity of ferment predonninates, a 
 certain quantity of it remains after all the sugar has fer- 
 mented, its decomposition proceeding very slowly, on 
 account of its insolubility in water. This residue of 
 ferment is still able to induce fermentation, when intro- 
 duced into a fresh solution of sugar, and retains the same 
 power until it has passed through all the stages of its 
 own transformation. 
 
 Hence a certain quantity of yeast is necessary in 
 order to effect the transformation of a certain portion of 
 sugar, not because it acts by its quantity increasing any 
 affinity, but because its influence depends solely on its 
 presence, and its presence is necessary, until the last 
 atom of sugar is decomposed. 
 
 These facts and observations point out the existence 
 of a new cause, which effects combinations and decom- 
 positions. This cause is the action which bodies in a 
 state of combination or decomposition exercise upon 
 substances, the component parts of which are united to- 
 gether by a feeble affinity. In its action it resembles a 
 peculiar power, attached to a body in the state of com- 
 bination or decomposition, but exerting its influence be- 
 yond the sphere of its own attractions. 
 
 We are now able to account satisfactorily for many 
 known phenomena. 
 
 A large quantity of hippuric * acid may be obtained 
 from the fresh urine of a horse, by the addition of mu- 
 riatic acid ; but when the urine has undergone putrefac- 
 tion, no trace of it can be discovered. The urine of 
 man contains a considerable quantity of urea, but when 
 the urine putrefies, the urea entirely disappears. When 
 
 * See Note, p. 138. 
 24 * 
 
2S2 YEAST, OR FERMENT. 
 
 urea is added to a solution of sugar in the state of fer- 
 mentation, it is deconriposed into carbonic acid and 
 ammonia. No asparagin * can be detected in a putrefied 
 infusion of asparagin, liquorice-root, or tlie root o( althcea 
 officinalis ( Marshmallovv) . 
 
 It has already been mentioned, that the strong affinity 
 of nitrogen for hydrogen, and that of carbon for oxygen, 
 is the cause of the facility with which the elements 
 of azotized compounds are disunited ; those affinities 
 aiding each other, inasmuch as by virtue of them dif- 
 ferent elements of the compound strive to take posses- 
 sion of the different elements of water. Now since it 
 is found that no body destitute of nitrogen possesses, 
 when pure, the property of decomposing spontaneously 
 whilst in contact with water, we must ascribe this prop- 
 erty which azotized bodies possess in so eminent a de- 
 gree, to something peculiar in the nature of the com- 
 pounds of nitrogen, and to their constituting, in a certain 
 measure, more highly organized atoms. 
 
 Every azotized constituent of ihe animal or vegetable 
 organism enters spontaneously into putrefaction, when 
 exposed to moisture and a high temperature. 
 
 Azotized matters are accordingly the only causes of 
 fermentation and putrefaction in vegetable substances. 
 
 Putrefaction, on account of its effects, as a mixed 
 transformation of many different substances, may be 
 classed with the most powerful processes of deoxidation, 
 by which the strongest affinities are overcome. 
 
 When a solution of gypsum in water is mixed with a 
 decoction of sawdust, or any other organic matter capa- 
 
 * A peculiar principle obtained from asparagus. See Brande's 
 Chemistry, p. 1042. 
 
NATURE OF FERMENTATION. 283 
 
 ble of putrefaction, and preserved in well-closed vessels, 
 it is found, after some time, that the solution contains no 
 more sulphuric acid, but in its place carbonic and free 
 hydrosulphuric acid, (sulphuretted hydrogen,) betvi^een 
 which the lime of the gypsum is shared. In stagnant 
 water containing sulphates in solution, crystallized py- 
 rites (sulphuret of iron) is observed to form on the de- 
 caying roots. 
 
 Now we know that in the putrefaction of wood under 
 water, when air therefore is excluded, a part of its car- 
 bon combines with the oxygen of the water, as well as 
 with the oxygen which the wood itself contains ; whilst 
 its hydrogen and that of the decomposed water are 
 liberated either in a pure state, or as carburetted hydro- 
 gen. The products of this decomposition are therefore 
 of the same kind as those generated when steam is con- 
 ducted over red-hot charcoal. 
 
 It is evident, that if with the water a substance contain- 
 ing a large quantity of oxygen, such as sulphuric acid, 
 be also present, the matters in the state of putrefaction 
 will make use of the oxygen of that substance as well as 
 that of the water, in order to form carbonic acid ; and 
 the sulphur and hydrogen being set free will combine 
 whilst in the nascent state, producing hydrosulphuric 
 acid, which will be again decomposed if metallic oxides 
 be present ; and the results of this second decomposi- 
 tion will be water and metallic sulphurets. 
 
 The putrefied leaves of looad (^Isatis tinctoria), in 
 contact with indigo-blue, water, and alkalies, suffer 
 further decomposition, and the indigo is deoxidized and 
 dissolved. 
 
 During the putrefaction of gluten, carbonic acid, and 
 pure hydrogen gas are evolved ; phosphate, acetate, 
 
284 YEAST, OR FERMENT. 
 
 caseate, and lactate of ammonia being at the same time 
 produced in such quantity, that the further decomposi- 
 tion of the gluten ceases. But when the supply of water 
 is renewed, the decomposition begins again, and in addi- 
 tion to the salts just mentioned, carbonate of ammonia 
 and a white crystalline matter resembling mica (caseous 
 oxide) are formed, together with hydrosulphate of am- 
 monia, and a mucilaginous substance coagulable by chlo- 
 rine. Lactic acid is almost always produced by the 
 putrefaction of organic bodies. 
 
 We may now compare fermentation and putrefaction 
 with the decomposition which organic compounds suffer 
 under the influence of a high temperature. Dry distil- 
 lation would appear to be a process of combustion or 
 oxidation going on in the interior of a substance, in 
 which a part of the carbon unites with all or part of the 
 oxygen of the compound, while other new compounds 
 containing a large proportion of hydrogen are necessarily 
 produced. Fermentation may be considered as a process 
 of combustion or oxidation of a similar kind, taking place 
 in a liquid between the elements of the same matter, at a 
 very slightly elevated temperature ; and putrefaction as a 
 process of oxidation, in which the oxygen of all the 
 substances present comes into play. 
 
 i 
 
DECAY. CONDITIONS FOR ITS OCCURRENCE. 285 
 
 CHAPTER VI. 
 
 EREMACAUSIS, OR DECAY. 
 
 In organic nature, besides the processes of decompo- 
 sition named fermentation and putrefaction, another and 
 not less striking class of changes occurs, which bodies 
 suffer from the influence of the air. This is the act of 
 gradual combination of the combustible elements of a 
 body with the oxygen of the air ; a slow combustion or 
 oxidation, to which we shall apply the term of erema- 
 causis.* 
 
 The conversion of wood into humus, the formation 
 of acetic acid out of alcohol, nitrification,! and numerous 
 other processes, are of this nature. Vegetable juices 
 of every kind, parts of animal and vegetable substances, 
 moist sawdust, blood, &c., cannot be exposed to the air, 
 without suffering immediately a progressive change of 
 color and properties, during which oxygen is absorbed, 
 these changes do not take place when water is excluded, 
 or when the substances are exposed to the temperature 
 of 32°, and it has been observed that different bodies 
 require different degrees of heat. In order to effect the ab- 
 sorption of oxygen, and, consequently, their eremacausis. 
 The property of suffering this change is possessed in the 
 highest degree by substances which contain nitrogen. 
 
 The conditions which determine the commencement 
 of eremacausis are of various kinds. Many organic sub- 
 stances, particularly such as are mixtures of several more 
 simple matters, oxidize in the air when simply moistened 
 
 * See page 95. t Formation of nitre, 
 
286 EREMACAUSIS, OR DECAY. 
 
 with water ; others not until they are subjected to the 
 action of alkahes ; but the greatest part of them undergo 
 this state of slow combustion or oxidation, when brought 
 in contact with other decaying matters.^ 
 
 The eremacausis of an organic matter is retarded 
 or completely arrested by all those substances which 
 prevent fermentation or putrefaction. Mineral acids, 
 salts of mercury, aromatic substances, empyreumatic 
 oils, and oil of turpentine, possess a similar action in this 
 respect. The latter substances have the same effect 
 on decaying bodies as on phosphuretted hydrogen, the 
 spontaneous inflammability of which they destroy. 
 
 Many bodies which do not decay when moistened 
 with water, enter into eremacausis when in contact with 
 an alkali. Gallic acid, haematin,* and many other com- 
 pounds, may be dissolved in water and yet remain un- 
 altered, but if the smallest quantity of a free alkali is 
 present, they acquire the property of attracting oxygen, 
 and are converted into a brown substance like humus, 
 evolving very frequently at the same time carbonic acid. 
 (Chevreul.) 
 
 A very remarkable kind of eremacausis takes place 
 in many vegetable substances, when they are exposed 
 to the influence of air, water, and ammonia. They 
 absorb oxygen very rapidly, and form splendid violet or 
 red-colored liquids, as in the case of orcin and erythrin.f 
 They now contain an azotized substance, not in the form 
 of ammonia. 
 
 All these facts show that the action of oxygen seldom 
 affects the carbon of decaying substances, and this cor- 
 responds exactly to what happens in combustion at high 
 
 * The colorinop matter of loorwood. 1 Coloring matters in archil. 
 
NATURE OF THE PROCESS. 287 
 
 temperatures. It is well known, for example, that when 
 no more oxygen is admitted to a compound of carbon 
 and hydrogen than is sufficient to combine with its hydro- 
 gen, the carbon is not burned, but is separated as lamp- 
 black;* while, if the quantity of oxygen is not suffi- 
 cient even to consume all the hydrogen, new compounds 
 are formed, such as naphthalin f and similar matters, 
 which contain a smaller proportion of hydrogen than 
 those compounds of carbon and hydrogen which pre- 
 viously existed in the combustible substance. 
 
 There is no example of carbon combining directly 
 with oxygen at common temperatures, but numerous facts 
 show that the hydrogen, in certain states of condensation, 
 possess that property. Lamp-black which has been 
 heated to redness may be kept in contact with oxygen 
 gas, without forming carbonic acid ; but lamp-black, 
 impregnated with oils which contain a large proportion 
 of hydrogen, gradually becomes warm, and inflames 
 spontaneously. The spontaneous inflammability of the 
 charcoal used in the fabrication of gunpowder has been 
 correctly ascribed to the hydrogen which it contains in 
 considerable quantity ; for during its reduction to powder, 
 no trace of carbonic acid can be detected in the air sur- 
 rounding it ; it is not formed until the temperature of the 
 mass has reached the red heat. The heat which pro- 
 duces the inflammation is therefore not caused by the 
 oxidation of the carbon. 
 
 The substances which undergo eremacausis may be 
 divided into two classes. The first class comprehends 
 those substances which unite with the oxygen of the air, 
 
 * As in the combustion of spirits of turpentine, now much em- 
 ployed under various names, in lamps, 
 t A substance obtained from coal tar. 
 
288 EREMACAUSIS, OR DECAY. 
 
 without evolving carbonic acid ; and the second, such 
 as emit carbonic acid by absorbing oxygen. 
 
 When the oil of bitter almonds is exposed to the air, 
 it absorbs two equivalents of oxygen, and is converted 
 into benzoic acid ; but half of the oxygen absorbed com- 
 bines with the hydrogen of the oil, and forms water, 
 which remains in union with the anhydrous benzoic 
 acid.* 
 
 But, although it appears very probable that the oxygen 
 acts primarily and principally upon hydrogen, the most 
 combustible constituent of organic matter in the state 
 of decay ; still it cannot thence be concluded that the 
 carbon is quite devoid of the power to unite with oxy- 
 gen, when every particle of it is surrounded with hydro- 
 gen, an element with which the oxygen combines with 
 greater facility. 
 
 We know, on the contrary, that nitrogen, which can- 
 not be made to combine with oxygen directly, is oxid- 
 ized and forms nitric acid, when mixed with a large 
 
 * According to the experiments of Dobereiner, 100 parts of pyro- 
 gallic acid absorb 38.09 parts of oxygen when in contact with ammo- 
 nia and water ; the acid being changed in consequence of this absorp- 
 tion into a mouldy substance, whicli contains less oxygen than the 
 acid itself. It is evident that the substance which is formed is not 
 a higher oxide; and it is found, on comparing the quantity of the 
 oxygen absorbed with that of tiie hydrogen contained in the acid, that 
 they are exactly in the proportions for forming water. 
 
 When colorless orcin is exposed together with ammonia to the 
 contact of oxj'gen gas, the beautiful red-colored orcein is produced. 
 Now, the only changes which take place here are, that the absorption 
 of oxygen by the elements of orcin and ammonia causes the formation 
 of water ; I equivalent of orcin Cl8 H12 08, and 1 equivalent of 
 ammonia, NH3 absorb .5 equivalents of oxygen, and 5 equivalents of 
 water are produced, the composition of orcein being C18 HIO 08 N. 
 (Dumas.) In this case it rs evident, that the oxygen absorbed has 
 united merely with the hydrogen. — L. 
 
NATURE OF THE PROCESS. 289 
 
 quantity of hydrogen, and burned in oxygen gas. In this 
 case its affinity is evidently increased by the combustion 
 of the hydrogen, which is in fact connmunicated to it. 
 It is conceivable, that, in a similar manner, the carbon 
 may be directly oxidized in several cases, obtaining from 
 its contact with hydrogen in eremacausis a property 
 which it does not itself possess at common temperatures. 
 But the formation of carbonic acid during the eremacau- 
 sis of bodies which contain hydrogen, must in most cases 
 be ascribed to another cause. It appears to be formed 
 in a manner similar to the formation of acetic acid, by 
 the eremacausis of saliculite of potash.* 
 
 An alkaline solution of haematin being exposed to an 
 atmosphere of oxygen, 0.2 Grm. absorb 23.6 cubic cen- 
 timeters of oxygen gas in twenty-four hours, the alkali 
 acquiring at the same time 6 cubic centimeters of car- 
 bonic acid. (Clievreul.) But these 6 cubic centime- 
 ters of carbonic acid contain only an equal volume of 
 oxygen, so that it is certain from this experiment that f^ 
 of the oxygen absorbed have not united with the carbon. 
 It is highly probable, that during the oxidation of the' 
 hydrogen, a portion of the carbon had united with the- 
 oxygen contained in the haematin, and had separated from 
 the other elements as carbonic acid. 
 
 The experiments of De Saussure upon the decay of 
 woody fibre, show that such a separation is quite possi- 
 ble. Moist woody fibre evolved one volume of carbonic 
 acid for every volume of oxygen which it absorbed. It 
 has just been mentioned that carbonic acid contains its 
 
 " This salt, when exposed to a moist atniospliere, absorbs 3 atoms of 
 oxygen ; mcJanic acid is produced, a bodj' resembling humus, in con- 
 sequence of the formation of which, the elements of 1 atom of acetic 
 acid are separated from the saliculous acid. — L. See Appendix. 
 25 
 
290 EREMACAUSIS, OR DECAY. 
 
 own volume of oxygen. Now, woody fibre contains 
 carbon and the elements of water, so that the result of 
 the action of oxygen upon it is exactly the same as if 
 pure charcoal had combined directly with oxygen. But 
 the characters of woody fibre show, that the elements of 
 water are not contained in it in the form of water ; for, 
 were this the case, starch, sugar, and gum must also be 
 considered as hydrates of carbon. 
 
 But if the hydrogen does not exist in woody fibre in 
 the form of water, the direct oxidation of the carbon 
 cannot be considered as at all probable, without reject- 
 ing all the facts established by experiment regarding the 
 process of combustion at low temperatures. 
 
 If we examine the action of oxygen upon such a sub- 
 stance as alcohol, which contains a large quantity of hy- 
 drogen, we find most distinctly, that the direct formation 
 of carbonic acid is the last stage of its oxidation, and that 
 it is preceded by a series of changes, the last of which 
 is a complete combustion of the hydrogen.* 
 
 The absorption of oxygen by drying oils certainly 
 does not depend upon the oxidation of their carbor> ; for 
 in raw nut-oil, for example, which was not free from 
 mucilage and other substances, only twenty-one volumes 
 
 * Aldehyde, acetic acid, formic acid, oxalic acid, and carbonic acid, 
 form a connected chain of products arising from the oxidation of alco- 
 hol ; and the successive changes which this fluid experiences from the 
 action of oxj'gen may be readily traced in them. Aldehyde is alcohol 
 viinus hydrogen ; acetic acid is formed by the direct union of alde- 
 hyde with oxygen. Formic acid and water are formed by the union 
 of acetic acid with oxygen. When all the hydrogen is removed from 
 this formic acid, oxalic acid is produced ; and the latter acid is con- 
 verted into carbonic acid by uniting with an additional portion of oxy- 
 gen. All these products appear to be formed simultaneously, by the 
 action of oxidizing agents on alcohol; but it can scarcely be doubted, 
 that the formation of the last ])rodnct,the carbonic acid, does not take 
 place until all the hydrogen has been abstracted. — L. 
 
NATURE OF THE PROCESS. 291 
 
 of carbonic acid were formed for every 146 volumes of 
 oxygen gas absorbed. 
 
 It must be remembered, that combustion or oxidation 
 at low temperatures produces results quite similar to 
 combustion at high temperatures with limited access of 
 air. The most combustible element of a compound, 
 which is exposed to the action of oxygen, must become 
 oxidized first, for its superior combustibility is caused by 
 its being enabled to unite with oxygen at a temperature 
 at which the other elements cannot enter into that combi- 
 nation ; this property having the same effect as a greater 
 affinity. 
 
 The combustibility of potassium is no measure of its 
 affinity for oxygen ; we have reason to believe that the 
 attraction of magnesium and aluminium for oxygen is 
 greater than that of potassium for the same element ; but 
 neither of those metals oxidizes either in air or water 
 at common temperatures, whilst potassium decomposes 
 water with great violence, and appropriates its oxygen. 
 
 Phosphorus and hydrogen combine with oxygen at 
 ordinary temperatures, the first in moist air, the second, 
 when in contact with finely-divided platinum ; while 
 charcoal requires a red heat before it can enter into 'Com- 
 bination with oxygen. It is evident that phosphorus and 
 hydrogen are more combustible than charcoal, that is, 
 that their affinity for oxygen at common temperatures is 
 greater ; and this is not the less certain, because it is 
 found, that carbon in certain other conditions shows a 
 much greater affinity for oxygen than either of those sub- 
 stances. 
 
 In putrefaction, the conditions are evidently present, 
 under which the affinity of carbon for oxygen comes into 
 play ; neither expansion, cohesion, nor the gaseous state 
 
292 EREMACAUSIS, OR DECAT, 
 
 opposes it, whilst in eretnacausis all these restraints have 
 to be overcome. 
 
 The evolution of carbonic acid during the decay or 
 eremacausis of animal or vegetable bodies, which are rich 
 in hydrogen, must accordingly be ascribed to a transpo- 
 sition of the elements or disturbance in their attractions, 
 similar to that which gives rise to the formation of car- 
 bonic acid in the processes of fermentation and putre- 
 faction. 
 
 The eremacausis of such substances is, therefore, a 
 decomposition analogous to the putrefaction of azotized 
 bodies. For in these there are two affinities at play ; 
 the affinity of nitrogen for hydrogen, and that of carbon 
 for oxygen, which facilitate the disunion of the elements. 
 Now there are two affinities also in action in those bodies 
 which decay with the evolution of carbonic acid. One 
 of these affinities is the attraction of the oxygen of the 
 air for the hydrogen of the substance, which corresponds 
 to the attraction of nitrogen for the same element ; and 
 the other is the affinity of the carbon of the substance for 
 its oxygen, which is constant under all circumstances. 
 
 When wood putrefies in marshes, carbon and oxygen 
 are separated from its elements in the form of carbonic 
 acid, and hydrogen in the form of carburetted hydrogen. 
 But when wood decays or putrefies in tlie air, its hydro- 
 gen does not combine with carbon, but with oxygen, for 
 which it has a much greater affinity at common tem- 
 peratures. 
 
 Now it is evident from the complete similarity of these 
 processes, that decaying and putrefying bodies can mu- 
 tually replace one another in their reciprocal actions. 
 
 All putrefying bodies pass into the state of decay 
 when exposed freely to the air ; and all decaying matters 
 
OF BODIES DESTITUTE OF NITROGEN. 293 
 
 into that of putrefaciion, when air is excluded. All 
 bodies, likewise, in a state of decay are capable of indu- 
 cing putrefaction in other bodies in the same manner as 
 putrefying bodies themselves do. 
 
 CHAPTER VII. 
 
 EREMACAUSIS, OR DECAY, OF BODIES WHICH DO NOT 
 CONTAIN NITROGEN : FORMATION OF ACETIC ACID. 
 
 All those substances which appear to possess the 
 property of entering spontaneously into fermentation and 
 putrefaction, do not in reality suffer those changes with- 
 out some previous disturbance in the attraction of their 
 elements. Eremacausis always precedes fermentation 
 and putrefaction, and it is not until after the absorption of 
 a certain quantity of oxygen that the signs of a transfor- 
 mation in the interior of the substances show themselves. 
 
 It is a very general error to suppose that organic sub- 
 stances have the power of undergoing change spontane- 
 ously, ivithout the aid of an external cause. When they 
 are not in a state of change, it is necessary, before they 
 can assume that state, that the existing equilibrium of 
 their elements should be disturbed ; and the most common 
 cause of this disturbance is undoubtedly the atmosphere 
 which surrounds all bodies. 
 
 The juices of the fruit or other part of a plant which 
 very readily undergo decomj)osition, retain their proper- 
 ties unchanged as long as they are protected from imme- 
 diate contact with the air, that is, as long as the cells or 
 organs in which they are contained resist the influence of 
 25* 
 
294 EREMACAUSIS, OR DECAY, 
 
 the air. It is not iiniil after tlie juices have been exposed 
 to the air, and have absorbed a certain quantity of oxygen, 
 that the substances dissolved in them begin to be decom- 
 posed. 
 
 The beautiful experiments of Gay-Lussac upon the 
 fermentation of the juice of grapes, as well as the im- 
 portant practical improvements to which they have led, 
 are the best proofs of the atmosphere having an influence 
 upon the changes of organic substances. The juice of 
 grapes which were expressed under a receiver filled with 
 mercury, so that air was completely excluded, did not 
 ferment. But when the smallest portion of air was in- 
 troduced, a certain quantity of oxygen became absorbed, 
 and fermentation immediately began. When the juice 
 was expressed from the grapes in contact with air, under 
 the conditions therefore necessary to cause its fermenta- 
 tion, still this change did not ensue when the juice was 
 heated in close vessels to the temperature of boiling 
 water. When thus treated, it could be preserved for 
 years without losing its property of fermenting. A fresh 
 exposure to the air at any period caused it to ferment. 
 
 Animal food of every kind, and even the most delicate 
 vegetables, may be preserved unchanged if healed to the 
 temperature of boiling water in vessels from which the 
 air is completely excluded. Food thus prepared has 
 been kept for fifteen years, and upon opening the vessels 
 after this long time, has been found as fresh and well- 
 flavored as when originally placed in them.* 
 
 * The process is as follows ; Let the substance to be preserved be 
 first parboiled, or rather somewhat more, the bones of the meat being 
 previously removed. Put the meat into a tin cylinder, fill up the 
 vessel with seasoned rich soup, and then solder on the lid, pierced 
 with a small hole. When this has been done, let the tin vessel thus 
 
OF BODIES DESTITUTE OF NITROGEN. 295 
 
 The action of the oxygen in these processes of de- 
 composition is very simple ; it excites changes in the 
 composition of the azoiized matters dissolved in the 
 juices; — the mode of combination of the elements of 
 those matters undergoes a disturbance and change in con- 
 sequence of their contact with oxygen. The oxygen 
 acts here in a similar manner to the friction or motion 
 which effects the mutual decomposition of two salts, the 
 crystallization of salts from their solution, or the explo- 
 sion of fulminating mercury. It causes the state of rest 
 to be converted into a state of motion. 
 
 When this condition of intestine motion is once ex- 
 cited, the presence of oxygen is no longer necessary. 
 The smallest particle of an azotized body in this act of 
 decomposition exercises an influence upon the particles 
 in contact with it, and the state of motion is thus propa- 
 gated through the substance. The air may now be com- 
 pletely excluded, but the fermentation or putrefaction 
 proceeds uninterruptedly to its completion. It has been 
 remarked that the mere contact of carbonic acid is suffi- 
 
 prepared be placed in brine and heated to the boiling point, to com- 
 plete the cooking of the meat. The hole of the lid is now to be 
 closed by soldering, whilst the air is rarefied. The vessel is then al- 
 lowed to cool, and from the diminution of volume, in consequence of 
 the reduction of temperature, both ends of the cylinder are pressed 
 inwards and become concave. The tin cases, thus hermetically 
 sealed, are exposed in a test-chamber, for at least a month, to a tem- 
 perature above what they are ever likely to encounter; from 90° to 
 110° F. If the process has failed, putrefaction takes place, and o-as 
 is evolved, which will cause the ends of the case to bulge, so as to 
 render them convex, instead of concave. But the contents of those 
 cases which stand the test will infallibly keep perfectly sweet and 
 good in any climate, and for any number of years. If there be any 
 taint about the meat when put up, it inevitably ferments, and is de- 
 tected in the proving process.— Ure's Diet, of Jlrts and Manuf. 
 
296 EREMACAUSIS, OR DECAY, 
 
 cient to produce fermentation in the juices of several 
 fruits. 
 
 Tlie contact of ammonia and alkalies in general may 
 be mentioned amongst the chemical conditions which de- 
 termine the commencement of eremacausis ; for their 
 presence causes many substances to absorb oxygen and 
 to decay, in which neither oxygen nor alkalies alone pro- 
 duce that change. 
 
 Thus alcohol does not combine with the oxygen of 
 the air at common temperatures. But a solution of pot- 
 ash in alcohol absorbs oxygen with much rapidity, and 
 acquires a brown color. The alcohol is found after a 
 short time to contain acetic acid, formic acid, and the 
 products of the decomposition of aldehyde by alkalies, 
 including aldehyde resin, which gives the liquid a brown 
 color. 
 
 The most general condition for the production of ere- 
 macausis in organic matter is contact with a body already 
 in the state of eremacausis or putrefaction. We have 
 here an instance of true contagion ; for the communica- 
 tion of the state of combustion is in reality the effect of 
 the contact. 
 
 It is decaying wood which causes fresh wood around 
 it to assume the same condition, and it is the very finely 
 divided woody fibre in the act of decay, which in moist- 
 ened gall-nuts converts the tannic acid with such rapidity 
 into gallic acid. 
 
 A most remarkable and decided example of this in- 
 duction of combustion has been observed by De Saussure. 
 It has already been mentioned, that moist woody fibre, 
 cotton, silk, or vegetable mould, in the act of fermenta- 
 tion or putrefaction, converts oxygen gas which may sur- 
 round it into carbonic acid, without change of volume. 
 
OF BODIES DESTITUTE OF NITROGEN, 297 
 
 Now, De Saussure added a certain quantity of hydrogen 
 gas to the oxygen, and observed a dinriinution in volume 
 immediately after the addition. A part of the hydrogen 
 gas had disappeared, and along with it a portion of the 
 oxygen, but a corresponding quantity of carbonic acid 
 gas had not been formed. The hydrogen and oxygen 
 had disappeared in exactly the same proportion as that in 
 which they combine to form water ; a true combustion 
 of the hydrogen, therefore, had been induced by mere 
 contact with matter in the slate of eremacausis. The 
 action of the decaying substance here produced results 
 exactly similar to those effected by spongy platinum ; 
 but that they proceeded from a different cause was shown 
 by the fact, that the presence of carbonic oxide, which 
 arrests completely the action of platinum on carburetted 
 hydrogen, did not retard in the slightest degree the 
 combustion of the hydrogen in contact with the decaying 
 bodies. 
 
 But the same bodies were found by De Saussure not 
 to possess the property just described, before they were 
 in a state of fermentation or decay ; and he has shown 
 that even when they are in this state, the presence of an- 
 tiseptic matter destroys completely all their influence. 
 
 Let us suppose a volatile substance containing a large 
 quantity of hydrogen, to be substituted for the hydrogen 
 gas in De Saussure's experiments. Now, the hydrogen 
 in such compounds being contained in a state of greater 
 condensation would suffer a more rapid oxidation, that is, 
 its combustion would be sooner completed. This prin- 
 ciple is in reality attended to in the manufactories in 
 which acetic acid is prepared according to the new plan. 
 In the process there adopted all the conditions are afford- 
 ed for the eremacausis of alcohol, and for its consequent 
 conversion into acetic acid. 
 
298 EREMACAUSIS, OR DECAY, 
 
 The alcohol is exposed to a moderate heat, and spread 
 over a very extended surface, but these conditions are 
 not sufficient to effect its oxidation. The alcohol must 
 be mixed with a substance which is with facility changed 
 by the oxygen of the air, and either enters into erema- 
 causis by mere contact with oxygen, or by its fermenta- 
 tion or putrefaction yields products possessed of this 
 property. 
 
 A small quantity of beer, acescent wine, a decoction 
 of malt, honey, and numerous other substances of this 
 kind, possess the action desired. 
 
 The difference in the nature of the substances which 
 possess this property shows, that none of them can con- 
 tain a peculiar matter which has the property of exciting 
 eremacausis ; they are only the bearers of an action, the 
 influence of which extends beyond the sphere of its own 
 attractions. Their power consists in a condition of de- 
 composition or eremacausis, which impresses the same 
 condition upon the atoms of alcohol in its vicinity ; ex- 
 actly as in the case of an alloy of platinum and silver 
 dissolving in nitric acid, in which the platinum becomes 
 oxidized, by virtue of an inductive action which the 
 silver in the act of its oxidation exercises upon it. The 
 hydrogen of the alcohol is oxidized at the expense of the 
 oxygen in contact with it, and forms water, evolving heat 
 at the same time ; the residue is aldehyde, a substance 
 which has as great an affinity for oxygen as sulphurous 
 acid, and combines, therefore, directly with it, producing 
 acetic acid. 
 
OF BODIES CONTAINING NITROGEN. 299 
 
 CHAPTER VIII. 
 
 EREMACAUSIS OF SUBSTANCES CONTAINING NITRO- 
 GEN. NITRIFICATION. 
 
 When azotized substances are burned at high tem- 
 peratures, tlifiir nitrogen does not enter into direct com- 
 bination with oxygen. The knowledge of this fact is of 
 assistance in considering the process of the eremacausis 
 of such substances. Azotized organic matter always 
 contains carbon and hydrogen, both of which elements 
 have a very strong affinity for oxygen. 
 
 Now nitrogen possesses a very feeble affinity for that 
 element, so that its compounds during their combustion 
 present analogous phenomena to those which are observed 
 in the combustion of substances containing a large pro- 
 portion of hydrogen and carbon ; a separation of the 
 carbon of the latter substances in an uncombined state 
 takes place, and in the same way the substances con- 
 taining nitrogen give out that element in its gaseous form. 
 
 When a moist azotized animal matter is exposed to the 
 action of the air, ammonia is always liberated, and nitric 
 acid is never formed. 
 
 But when alkalies or alkaline bases are present, a union 
 of oxygen with the nitrogen lakes place under the same 
 circumstances, and nitrates are formed together with the 
 other products of oxidation. 
 
 Although we see the most simple means and direct 
 methods employed in the great processes of decomposition 
 which proceed in nature, still we find that the final re- 
 sult depends on a succession of actions, which are es- 
 sentially influenced by the chemical nature of the bodies 
 submitted to decomposition. 
 
300 EREMACAUSIS, OR DECAY, 
 
 When it is observed that the character of a substance 
 remains unaltered in a whole series of phenomena, there 
 is no reason to ascribe a new character to it, for the 
 purpose of explaining a single phenomenon, especially 
 where the explanation of that according to known facts 
 offers no difficulty. 
 
 The most distinguished philosophers suppose that the 
 nitrogen in an animal substance, when exposed to the 
 action of air, water, and alkaline bases, obtains the 
 power to unite directly with oxygen, and form nitric 
 acid, but we are not acquainted with a single fact which 
 justifies this opinion. It is only by the interposition of 
 a large quantity of hydrogen in the stale of combustion 
 or oxidation, that nitrogen can be converted into an 
 oxide. 
 
 When a compound of nitrogen and carbon, such as 
 cyanogen, is burned in oxygen gas, its carbon alone is 
 oxidized ; and when it is conducted over a metallic 
 oxide heated to redness, an oxide of nitrogen is very 
 rarely produced, and never when the carbon is in ex- 
 cess. Kuhlmann found in his experiments, that it was 
 only when cyanogen was mixed with an excess of oxy- 
 gen gas, and conducted over spongy platinum, that 
 nitric acid was generated. 
 
 Kuhlmann could not succeed in causing pure nitrogen 
 to combine directly with oxygen, even under the most 
 favorable circumstances ; thus, vviih the aid of spongy 
 platinum at different temperatures, no union took place. 
 
 The carbon in the cyanogen gas must, therefore, 
 have given rise to the combustion of the nitrogen by 
 induction. 
 
 On the other hand we find that ammonia, which is a 
 compoufTd of hydrogen and nitrogen, cannot be exposed 
 
OF BODIES CONTAINING NITROGEN. 301 
 
 to the action of oxygen, without the formation of an 
 oxide of nitrogen, and in consequence the production of 
 nitric acid. 
 
 It is owing to the great facility with which ammonia 
 is converted into nitric acid, that it is so difficult to ob- 
 tain a correct determination of the quantity of nitrogen 
 in a compound subjected to analysis, in which it is 
 either contained in the form of ammonia, or from which 
 ammonia is formed by an elevation of temperature. For 
 when ammonia is passed over red-hot oxide of copper, 
 it is converted either completely or partially, into bin- 
 oxide of nitrogen. 
 
 When ammoniacal gas is conducted over peroxide 
 of manganese or iron heated to redness, a large quantity 
 of nitrate of ammonia is obtained, if the ammonia be in 
 excess ; and the same decomposition happens, when 
 ammonia and oxygen are together passed over red-hot 
 spongy platinum. 
 
 It appears, therefore, that the combination of oxygen 
 with nitrogen occurs rarely during the combustion of 
 compounds of the latter element with carbon, but that 
 nitric acid is always a product when ammonia is present 
 in the substance exposed to oxidation. 
 
 The cause wherefore the nitrogen in ammonia exhib- 
 its such a strong disposition to become converted into 
 nitric acid is undoubtedly, that the two products, which 
 are the result of the oxidation of the constituents of am- 
 monia, possess the power of uniting with one another. 
 Now this is not the case in the combustion of com- 
 pounds of carbon and nitrogen ; here one of the pro- 
 ducts is carbonic acid, which on account of its gaseous 
 form, must oppose the combination of the oxygen and 
 nitrogen, by preventing their mutual contact, while the 
 26 
 
302 EREMACAUSIS, OR DECAY. 
 
 superior affinity of its carbon for the oxygen during the 
 act of its formation will aid in this effect. 
 
 When sufficient access of air is admitted during the 
 combustion of ammonia, water is formed as well as 
 nitric acid, and both of these bodies combine together. 
 The presence of water may, indeed, be considered as 
 one of the conditions df nitrification, since nitric acid 
 cannot exist without it. 
 
 Eremacausis is a kind of putrefaction, differing from 
 the common process of putrefaction, only in the part 
 which the oxygen of the air plays in the transformations 
 of the body in decay. When this is remembered, and 
 when it is considered, that in the transposition of the 
 elements of azotized bodies their nitrogen assumes the 
 form of ammonia, and that in this form, nitrogen pos- 
 sesses a much greater disposition to unite with oxygen 
 than it has in any of its other compounds ; we can with 
 difficulty resist the conclusion, that ammonia is the gen- 
 eral cause of nitrification on the surface of the earth. 
 
 Azotized animal matter is not, therefore, the imme- 
 diate cause of nitrification, it contributes to the produc- 
 tion of nitric acid only in so far as it is a slow and 
 continued source of ammonia. 
 
 Now it has been shown in the former part of this 
 work, that ammonia is always present in the atmo- 
 sphere, so that nitrates might thence be formed in sub- 
 stances which themselves contained no azotized matter. 
 It is known also, that porous substances possess gener- 
 ally the power of condensing ammonia ; there are few 
 ferruginous earths which do not evolve ammoniacal pro- 
 ducts when healed to redness, and ammonia is the 
 cause of the peculiar smell perceived upon moistening 
 aluminous minerals. Thus, ammonia, by being a con- 
 
VINOUS FERMENTATION. 303 
 
 stituent of the atmosphere, is a very widely diffused 
 cause of nitrification, which will come into play when- 
 ever the different conditions necessary for the oxidation 
 of ammonia are combined. It is probable that other 
 organic bodies in the state of eremacausis are the means 
 of causing the combustion of ammonia ; at all events, 
 the cases are very rare, in which nitric acid is generat- 
 ed from ammonia, in the absence of all matter capable 
 of eremacausis. 
 
 From the preceding observations on the causes of 
 fermentation, putrefaction, and decay, we may now 
 draw several conclusions calculated to correct the views 
 generally entertained respecting the fermentation of 
 wine and beer, and several other important processes of 
 decomposition which occur in nature. 
 
 CHAPTER IX. 
 
 ON VINOUS fermentation: WINE AND BEER. 
 
 It has already been mentioned, that fermentation is 
 excited in the juice of grapes by the access of air ; 
 alcohol and carbonic acid being formed by the decom- 
 position of the sugar contained in the jfluid. But it was 
 also stated, that the process once commenced, continues 
 until all the sugar is completely decomposed, quite in- 
 dependently of any further influence of the air. 
 
 In addition to the alcohol and carbonic acid formed 
 by the fermentation of the juice, there is also produced 
 a yellow or gray insoluble substance, which contains a 
 large quantity of nitrogen. It is this body which pos- 
 
304 VINOUS FERMENTATION. 
 
 sesses the power of inducing fermentation in a new 
 solution of sugar, and which has in consequence receiv- 
 ed the name o{ ferment. 
 
 The alcohol and carbonic acid are produced from 
 the elements of the sugar, and the ferment from those 
 azotized constituents of the grape juice, which have 
 been termed gluten, or vegetable albumen. 
 
 According to the experiments of De Saussure, fresh 
 impure gluten evolved, in five weeks, twenty-eight times 
 its volume of a gas of which 3 consisted of carbonic 
 acid, and 5 of pure hydrogen gas ; ammoniacal salts of 
 several organic acids were formed at the same time. 
 Water must, therefore, be decomposed during the pu- 
 trefaction of gluten ; the oxygen of this water must enter 
 into combination with some of its constituents, whilst 
 hydrogen is liberated, a circumstance which happens 
 only in decompositions of the most energetic kind. 
 Neither ferment nor any substance similar to it is form- 
 ed in this case ; and we have seen that in the fermenta- 
 tion of saccharine vegetable juices, no escape of hydro- 
 gen gas takes place. 
 
 It is evident that the decomposition which gluten 
 suffers in an isolated state, and that which it undergoes 
 when dissolved in a vegetable juice, belong to two dif- 
 ferent kinds of transformations. There is reason to 
 believe that its change to the insoluble state depends 
 upon an absorption of oxygen, for its separation in this 
 state may be effected under certain conditions, by free 
 exposure to the air, without the presence of fermenting 
 sugar. It is known also that the juice of grapes, or 
 vegetable juices in general, become turbid when in con- 
 tact with air, before fermentation commences ; and this 
 
YEAST FROM BEER AND WINE. 305 
 
 turbidity is owing to the formation of an insoluble pre- 
 cipitate of the same nature as ferment. 
 
 From the phenomena which have been observed dur- 
 ing the fermentation of wort,* it is known with perfect 
 certainty that ferment is formed from gluten at the same 
 time that the transformation of the sugar is effected ; 
 for the wort contains the azotized matter of the corn, 
 namely, gluten in the same condition as it exists in the 
 juice of grapes. The wort ferments by the addition of 
 yeast, but after its decomposition is completed, the 
 quantity of ferment or yeast is found to be thirty times 
 greater than it was originally. 
 
 Yeast from beer and that from wine, examined under 
 the microscope, present the same form and general 
 appearance. They are both acted on in the same 
 manner by alkalies and acids, and possess the power of 
 inducing fermentation anew in a solution of sugar ; in 
 short they must be considered as identical. 
 
 The fact, that water is decomposed during the putre- 
 faction of gluten has been completely proved. The 
 tendency of the carbon of the gluten to appropriate the 
 oxygen of water must also always be in action, whether 
 the gluten is decomposed in a soluble or insoluble state. 
 These considerations, therefore, as well as the circum- 
 stance which all the experiments made on this subject 
 appear to point out, that the conversion of gluten to the 
 insoluble state is the result of oxidation, lead us to con- 
 clude that the oxygen consumed in this process is de- 
 rived from the elements of water, or from the sugar 
 which contains oxygen and hydrogen in the same pro- 
 
 * Wort is an infusion of malt ; it consists of insoluble parts of this 
 substance dissolved in water. — Trans. 
 26* 
 
306 VINOUS FERMENTATION. 
 
 portion as water. At all events, the oxygen thus con- 
 sumed in the fermentation of wine and beer is not taken 
 from the atmosphere. 
 
 The fermentation of pure sugar in contact with yeast 
 must evidently be a very different process from the 
 fermentation of wort or must.* 
 
 In the former case, the yeast disappears during the 
 decomposition of the sugar ; but in the latter, a trans- 
 formation of glulen is effected at the same time, by 
 which ferment is generated. Thus yeast is destroyed 
 in the one case, but is formed in the other. 
 
 Now since no free hydrogen gas can be detected 
 during the fermentation of beer and wine, it is evident 
 that the oxidation of the gluten, that is, its conversion 
 into ferment, must take place at the cost either of the 
 oxygen of the water, or of that of the sugar ; whilst the 
 hydrogen which is set free must enter into new combi- 
 nations, or by the deoxidation of the sugar, new com- 
 pounds containing a large proportion of hydrogen, and 
 small quantity of oxygen, together with the carbon of 
 the sugar, must be formed. 
 
 It is well known that wine and fermented liquors 
 generally contain, in addition to the alcohol, other sub- 
 stances which could not be detected before their fer- 
 mentation, and which must have been formed, therefore, 
 during that process in a manner similar to the produc- 
 tion of mannite. The smell and taste which distinguish 
 wine from all other fermented liquids are known to de- 
 pend upon an ether of a volatile and highly combustible 
 acid, which is of an oily nature, and to which the name 
 of (Enanthic ether has been given. It is also ascertain- 
 
 * The liquid expressed from grapes when fully ripe is called must. 
 
OILY AND ETHEREAL PRODUCTS. 307 
 
 ed that the smell and taste of brandy from corn and 
 potatoes is owing to a peculiar oil, the oil of potatoes. 
 This oil is more closely allied to alcohol in its proper- 
 ties, than to any other organic substance. 
 
 These bodies are products of the deoxidation of the 
 substances dissolved in the fermenting liquids ; they 
 contain less oxygen than sugar or gluten, but are re- 
 markable for the large quantity of hydrogen which en- 
 ters into their composition. 
 
 CEnanthic acid contains an equal number of equiva- 
 lents of carbon and hydrogen, exactly the same propor- 
 tions of these elements, therefore, as sugar, but by no 
 means the same proportion of oxygen. The oil of 
 potatoes contains much more hydrogen. 
 
 Although it cannot be doubted that these volatile 
 liquids are formed by a mutual interchange of the ele- 
 ments of gluten and sugar, in consequence, therefore, 
 of a true process of putrefaction, still it is certain, that 
 other causes exercise an influence upon their production 
 and peculiarities. 
 
 The substances in wine to which its taste and smell 
 are owing are generated during the fermentation of the 
 juice of such grapes as contain a certain quantity of 
 tartaric acid ; they are not found in wines which are 
 free from all acid, or which contain a different organic 
 acid, such as acetic acid. 
 
 The wines of warm climates possess no odor ; wines 
 grown in France have it in a marked degree, but in the 
 wines from the Rhine the perfume is most intense. 
 The kinds of grapes on the Rhine, which ripen very 
 late, and scarcely ever completely, such as the Reiss- 
 ling and Orleans^ have the strongest perfume or bou- 
 quet^ and contain, proportionally, a larger quantity of 
 
308 VINOUS FERMENTATION. 
 
 tartaric acid. The earlier grapes, such as the Ruldn- 
 der and others, contain a large proportion of alcohol, 
 and are similar to Spanish wines in their flavor, but 
 they possess no bouquet. 
 
 The grapes grown at the Cape from Riesslings trans- 
 plated from the Rhine, produce an excellent wine, 
 which does not however possess the aroma which dis- 
 tinguishes Rhenish wine. 
 
 It is evident from these facts, that the acid of wines, 
 and their characteristic perfumes, have some connex- 
 ion, for they are always found together, and it can 
 scarcely be doubted that the presence of the former 
 exercises a certain influence on the formation of the 
 latter. This influence is very plainly observed in the 
 fermentation of liquids, which are quite free from tar- 
 taric acid, and particularly of those which are nearly 
 neutral or alkaline, such as the mash* of potatoes or 
 corn. 
 
 The brandy obtained from corn and potatoes con- 
 tains an ethereal oil of a similar composition in both, to 
 which these liquors owe their peculiar smell. This oil 
 is generated during the fermentation of the mash; it ex- 
 ists ready formed in the fermented liquids, and distils 
 over with alcohol, when a gentle heat is applied. 
 
 It is observed that a greater quantity of alcohol is 
 obtained when the mash is made quite neutral by means 
 of ashes or carbonate of lime, but that the proportion of 
 oil in the brandy is also increased. 
 
 Now it is known that brandy made from potato 
 starch, which has been converted into sugar by dilute 
 
 * Mash is the mixture of malt, potatoes, and water, in the mask 
 tun, a large vessel in which it is infused. — Trans. 
 
OILr AND ETHEREAL PRODUCTS. 309 
 
 sulphuric acid, is completely free from ihe potato oil, 
 so that this substance must be generated in consequence 
 of a change suffered by the cellular tissue of the pota- 
 toes during their fermentation. 
 
 Experience has shown that the simultaneous fermen- 
 tation or putrefaction of the cellular tissue, by which 
 this oil is generated, may be completely prevented in 
 the fabrication of brandy from corn.* 
 
 The same malt, which in the preparation of brandy 
 yields a fluid containing the oil of which we are speak- 
 ing, affords in the formation of beer a spirituous liquor, 
 in which no trace of that oil can be detected. The 
 principal difference in the preparation of the two liquids 
 is, that in the fermentation of wori^ an aromatic sub- 
 stance [hops] is added, and it is certain that its pres- 
 ence modifies the transformations which take place. 
 Now it is known, that the volatile oil of mustard, and 
 the empyreumatic oils, arrest completely the action of 
 yeast ; and although the oil of hops does not possess 
 this property, still it diminishes, in a great degree, the 
 influence of decomposing azotized bodies upon the con- 
 version of alcohol into acetic acid. There is, therefore, 
 reason to believe that some aromatic substances, when 
 added to fermenting mixtures, are capable of producing 
 very various modifications in the nature of the products 
 generated. 
 
 Whatever opinion, however, may be held regarding 
 the origin of the volatile odoriferous substances obtained 
 in the fermentation of wine, it is quite certain that the 
 
 * In the manufactory of M. Diibrunfaut, so considerable a quan- 
 tity of this oil is obtained under certain circumstances from brandy 
 made from potatoes, that it might be employed for the purpose of illu- 
 minating his whole manufactory. — L. 
 
310 VINOUS FERMENTATION. 
 
 characteristic smell of wine is owing to an ether of an 
 organic acid, resembhng one of the fatty acids. 
 
 It is only in liquids which contain other very soluble 
 acids, that the fatty acids and oenanthic acid are capable 
 of entering into combination with the ether of alcohol, 
 and of thus producing compounds of a peculiar smell. 
 This ether is found in all wines which contain free acid, 
 and is absent from those in which no acids are present. 
 This acid, therefore, is the means by which the smell is 
 produced ; since without its presence cenanthic ether 
 could not be formed. 
 
 The greatest part of the oil of brandy made from 
 corn consists of a fatty acid not converted into ether ; 
 it dissolves oxide of copper and metallic oxides in gen- 
 eral, and combines with the alkalies. 
 
 The principal constituent of this oil is an acid identi- 
 cal in composition with oenanthic acid, but different in 
 properties (Mulder). It is formed in fermenting liquids, 
 which, if they be acid, contain only acetic acid, a body 
 which has no influence in causing other acids to form 
 ethers. 
 
 The oil of brandy made from potatoes is the hydrate 
 of an organic base analogous to ether, and capable, 
 therefore, of entering into combination with acids. It 
 is formed in considerable quantity in fermenting liquids 
 which are slightly alkaline, under circumstances, conse- 
 quently, in which it is incapable of combining with an 
 acid. 
 
 The products of the fermentation and putrefaction of 
 neutral vegetable and animal matters, are generally ac- 
 companied by substances of an offensive odor ; but the 
 most remarkable example of the generation of a true 
 ethereal oil, is seen in the fermentation of the Hcrba 
 
ODORIFEROUS PRODUCTS. 311 
 
 centaurium minorius^ a plant which possesses no smell. 
 When it is exposed in water to a slightly elevated tem- 
 perature it ferments, and emits an agreeable penetrating 
 odor. By the distillation of the hquid, an ethereal oily 
 substance of great volatility is obtained, which excites a 
 pricking sensation in the eyes, and a flow of tears 
 (^Bilchner) . 
 
 The leaves of the tobacco plant present the same 
 phenomena ; when fresh, they possess very little or no 
 smell. When they are subjected to distillation with 
 water, a weak ammoniacal liquid is obtained, upon 
 which a white fatty crystallizable substance swims, 
 which does not contain nitrogen, and is quite destitute 
 of smell. But when the same plant, after being dried, 
 is moistened with water, tied together in small bundles, 
 and placed in heaps, a peculiar process of decomposition 
 takes place. Fermentation commences, and is accom- 
 panied by the absorption of oxygen ; the leaves now 
 become warm and emit the characteristic smell of pre- 
 pared tobacco and snufF. When the fermentation is 
 carefully promoted and too high a heat avoided, this 
 smell increases and becomes more delicate ; and after 
 the fermentation is completed, an oily azotized volatile 
 matter called nicotine is found in the leaves. This sub- 
 stance, — nicotine.^ which possesses all the properties of 
 a base, was not present before the fermentation. The 
 different kinds of tobacco are distinguished from one 
 another, like wines, by having very different odoriferous 
 substances, which are generated along with the nico- 
 tine. 
 
 We know that most of the blossoms and vegetable 
 substances which possess a smell, owe this property to 
 a volatile oil existing in them ; but it is not less certain. 
 
312 VINOUS FERMENTATION. 
 
 that others emit a smell only when they undergo change 
 or decomposition. 
 
 Arsenic and arsenious acid are both quite inodorous. 
 It is only during their oxidation that they emit their 
 characteristic odor of garlic. The oil of the berries of 
 the elder tree, many kinds of oil of turpentine, and oil 
 of lemons, possess a smell only during their oxidation or 
 decay. The same is the case with many blossoms ; and 
 Geiger has shown, that the smell of musk is owing to 
 its gradual putrefaction and decay. 
 
 It is also probable, that the peculiar odorous principle 
 of many vegetable substances is newly formed during 
 the fermentation of the saccharine juices of the plants. 
 At all events, it is a fact, that very small quantities of 
 the blossoms of the violet, elder, linden, or cowslip, 
 added to a fermenting liquid, are sufficient to communi- 
 cate a very strong taste and smell, which the addition of 
 the water distilled from a quantity a hundred times 
 greater would not affect. The various kinds of beer 
 manufactured in Bavaria are distinguished by different 
 flavors, which are given by allowing small quantities of 
 the herbs and blossoms of particular plants to ferment 
 along with the wort. On the Rhine, also, an artificial 
 bouquet is often given to wine for fraudulent purposes, by 
 the addition of several species of the sage and rue to the 
 fermenting liquor ; but the perfumethus obtained differs 
 from the genuine aroma, by its inferior durability, it be- 
 ing gradually dissipated. 
 
 The juice of grapes grown in different climates dif- 
 fers not only in the proportion of free acid which it con- 
 tains, but also in respect of the quantity of sugar dis- 
 solved in it. The quantity of azotized matter in the 
 juice seems to be the same in whatever part the grapes 
 
 i 
 
VARIOUS PROPERTIES OF WINES. 313 
 
 may grow ; at least no difference has been observed in 
 the amount of yeast fornned during fernnentation in the 
 south of France, and on the Rhine. 
 
 The grapes grown in hot chmates, as well as the 
 boiled juice obtained from them, are proportionally rich 
 in sugar. Hence, during the fermentation of the juice, 
 the complete decomposition of its azotized matters, and 
 their separation in the insoluble state, are effected before 
 all the sugar has been converted into alcohol and car- 
 bonic acid. A certain quantity of the sugar consequent- 
 ly remains mixed with the wine in an undecomposed 
 state, the condition necessary for its further decomposi- 
 tion being absent. 
 
 The azotized matters in the juice of grapes of the 
 temperate zones, on the contrary, are not completely 
 separated in the insoluble state, when the entire transfor- 
 mation of the sugar is effected. The wine of these 
 grapes, therefore, does not contain sugar, but variable 
 quantities of undecomposed gluten in solution. 
 
 This gluten gives the wine the property of becoming 
 spontaneously converted into vinegar, when the access 
 of air is not prevented. For it absorbs oxygen and be- 
 comes insoluble ; and its oxidation is communicated to 
 the alcohol, which is converted inlo acetic acid. 
 
 By allowing the wine to remain at rest in casks with 
 a very limited access of air, and at the lowest possible 
 temperature, the oxidation of this azotized matter is ef- 
 fected without the alcohol undergoing the same change, 
 a higher temperature being necessary to enable alcohol 
 to combine with oxygen. As long as the wine in the 
 s^^7/mo•-ccr.s/(:5 deposits yeast, it can still be caused to fer- 
 ment by the addition of sugar, but old well-layed wine- 
 has lost this property, because the condition necessary 
 27 
 
314 FERMENTATION OF BEER. 
 
 for fermentation, namely, a substance in the act of de- 
 composition or putrefaction, is no longer present in it. 
 
 In hotels and other places where the wine is drawn 
 gradually from a cask, and a proportional quantity of air 
 necessarily introduced, its eremacausis, that is, its conver- 
 sion into acetic acid, is prevented by the addition of a 
 small quantity of sulphurous acid. This acid, by uniting 
 itself with the oxygen of the air contained in the cask, 
 or dissolved in the wine, prevents the oxidation of the 
 organic matter. 
 
 The various kinds of beer differ from one another in 
 the same way as the wines. 
 
 English, French, and most of the German beers, are 
 converted into vinegar when exposed to the action of 
 air. But this property is not possessed by Bavarian 
 beer, which may be kept in vessels only half-filled with- 
 out acidifying or experiencing any change. This valua- 
 ble quality is obtained for it by a peculiar management 
 of the fermentation of the wort. The perfection of ex- 
 perimental knowledge has here led to the solution of one 
 of the most beautiful problems of the theory of fermen- 
 tation. 
 
 Wort is proportionally richer in gluten than in sugar, 
 so that during its fermentation in the common way, a 
 great quantity of yeast is formed as a thick scum. The 
 carbonic acid evolved during the process attaches itself 
 to the particles of the yeast, by which they become spe- 
 cifically lighter than the liquid in which they are formed, 
 and rise to its surface. Gluten in the act of oxidation 
 comes in contact with the particles of the decomposing 
 sugar in the interior of the liquid. The carbonic acid 
 from the sugar, and insoluble ferment from the gluten, 
 are disen"ao;ed simultaneously, and co!:ere together. 
 
THE BAVARIAN PROCESS. 315 
 
 A great quantity of gluten remains dissolved in the 
 fermented liquid, even after the transformation of the su- 
 gar is completed, and this gluten causes the conversion 
 of the alcohol into acetic acid, on account of its strong 
 disposition to attract oxygen, and to undergo decay. 
 Now, it is plain, that with its separation, and that of all 
 substances capable of attracting oxygen, the beer would 
 lose the property of becoming acid. This end is com- 
 pletely attained in the process of fermentation adopted in 
 Bavaria. 
 
 The wort, after having been treated with hops in the 
 usual manner, is thrown into very wide, flat vessels, in 
 which a large surface of the liquid is exposed to the air. 
 The fermentation is then allowed to proceed while the 
 temperature of the chambers in which the vessels are 
 placed, is never allowed to rise above from 45° to 50^ 
 F. The fermentation lasts from three to six weeks, and 
 the carbonic acid evolved during its continuance is not 
 in large bubbles which burst upon the surface of the li- 
 quid, but in small bubbles like those which escape from 
 a liquid saturated by high pressure. The surface of the 
 wort is scarcely covered with a scum, and all the yeast 
 is deposited on the bottom of the vessel in the form of a 
 viscous sediment. 
 
 In order to obtain a clear conception of the great dif- 
 ference between the two kinds of fermentation, it may 
 perhaps be sufficient to recall to mind the fact, that the 
 transformation of gluten or other azotized matters is a 
 process consisting of several stages. The first stage is 
 the conversion of the gluten into insoluble ferment in the 
 interior of the liquid, and as the transformation of the su- 
 gar goes on at the same time, carbonic acid and yeast are 
 simultaneously disengaged. It is known with certainty, 
 
316 FERMENTATION OF BEER. 
 
 that this formation of yeast depends upon oxygen being 
 appropriated by the gluten in the act of decomposition ; 
 but it has not been sufficiently shown, whether this oxy- 
 gen is derived from the water, sugar, or from the gluten 
 itself; whether it combines directly with the gluten, or 
 merely with its hydrogen, so as to form water. For the 
 purpose of obtaining a definite idea of the process, we 
 may designate the first change as the stage of oxidation. 
 This oxidation of the gluten then, and the transposition 
 of the atoms of the sugar into alcohol and carbonic acid, 
 are necessarily attendant on each other, so that if the one 
 is arrested the other must also cease. 
 
 Now, the yeast which rises to the surface of the liquid 
 is not the product of a complete decomposition, but is 
 oxidized gluten still capable of undergoing a new trans- 
 formation by the transposition of its constituent elements. 
 By virtue of this condition, it has the power to excite fer- 
 mentation in a solution of sugar ; and if gluten be also 
 present, the decomposing sugar induces its conversion 
 into fresh yeast, so that, in a certain sense, the yeast ap- 
 pears to reproduce itself. 
 
 Yeast of this kind is oxidized gluten in a state of pu- 
 trefoction, and by virtue of this state it induces a similar 
 transformation in the elements of the sugar. 
 
 The yeast formed during the fermentation of Bavarian 
 beer is oxidized gluten in a state of decay. The process 
 of decomposition which its constituents are suffering, 
 gives rise to a very protracted putrefaction (^fermenta- 
 tioii) in the sugar. The intensity of the action is di- 
 minished in so great a degree, that the gluten which the 
 fluid still holds in solution takes no part in it ; the sugar 
 in fermentation does not excite a similar state in the glu- 
 ten. 
 
THE BAVARIAN PROCESS. 317 
 
 But the contact of the already decaying and precipi- 
 tated gluten or yeast, causes the eremacausis of the glu- 
 ten dissolved in the wort ; oxygen gas is absorbed from 
 the air, and all the gluten in solution is deposited as 
 yeast. 
 
 The ordinary frothy yeast may be removed from fer- 
 menting beer by filtration, without the fermentation being 
 thereby arrested ; but precipitated yeast of Bavarian beer 
 cannot be removed without the whole process of its fer- 
 mentation being interrupted. The beer ceases to fer- 
 ment altogether, or, if the temperature is raised, under- 
 goes the ordinary fermentation. 
 
 The precipitated yeast does not excite ordinary fer- 
 mentation, and consequently is quite unfitted for the pur- 
 pose of baking, but the common frothy yeast can cause 
 the kind of fermentation by which the former kind of 
 yeast is produced. 
 
 When comtnon yeast is added to wort at a tempera- 
 ture of between 40^ and 45"^ F., a slow, tranquil fer- 
 mentation takes place, and a matter is deposited on the 
 bottom of the vessel, which may be employed to excite 
 new fermentation ', and when the same operation is re- 
 peated several times in succession, the ordinary fermenta- 
 tion changes into that process by which only precipitat- 
 ed yeast is formed. The yeast now deposited has lost 
 the property of exciting ordinary fermentation, but it 
 produces the other process even at a temperature of 
 50° F. 
 
 In wort subjected to fermentation, at a low tempera- 
 ture, with this kind of yeast, the condition necessary for 
 the transformation of the sugar is the presence of that 
 yeast ; but for the conversion of gluten into ferment by 
 a process of oxidation, something more is required. 
 27* 
 
318 FERMENTATION OF BEER. 
 
 When the power of gluten to attract oxygen is in- 
 creased by contact with precipitated yeast in a slate of 
 decay, the unrestrained access of air is the only other 
 condition necessary for its own conversion into the same 
 state of decay, that is for its oxidation. We have 
 already seen that the presence of free oxygen and gluten 
 are conditions which determine the eremacausis of alco- 
 hol and its conversion into acetic acid, but they are 
 incapable of exerting this influence at low temperatures. 
 A low temperature retards the slow combustion of alco- 
 hol, while the gluten combines spontaneously with the 
 oxygen of the air, just as sulphurous acid does when 
 dissolved in water. Alcohol undergoes no such change 
 at low temperatures, but during the oxidation of the 
 gluten in contact with it, is in the same condition as the 
 gluten itself is placed in when sulphurous acid is added 
 to the wine in which it is contained. The oxygen of 
 the air unites both with the gluten and alcohol of wine 
 not treated with sulphurous acid, but when this acid is 
 present it combines with neither of them, being alto- 
 gether absorbed by the acid. The same thing happens 
 in the peculiar process of fermentation adopted in Ba- 
 varia. The oxygen of the air unites only with the gluten 
 and not with the alcohol, although it would have com- 
 bined with both at higher temperatures, so as to form 
 acetic acid. 
 
 Thus, then, this remarkable process of fermentation 
 with the precipitation of a mucous-like ferment consists 
 of a simultaneous putrefaction and decay in ihe same 
 liquid. The sugar is in the state of putrefaction, and 
 the gluten in that of decay. 
 
 Jippert''s method of preserving food (p. 294), and this 
 kind of fermentation of beer, depend on the same prin- 
 ciple. 
 
THE BAVARIAN PROCESS. 319 
 
 In the fermentation of beer after this manner, all the 
 substances capable of decay are separated from it by 
 means of an unrestrained access of air, while the tempera- 
 ture is kept sufficiently low to prevent the alcohol from 
 combining with oxygen. The removal of these sub- 
 stances diminishes the tendency of the beer to become 
 acescent, or, in other words, to suffer a further trans- 
 formation. 
 
 In JlpperVs mode of preserving food, oxygen is al- 
 lowed to enter into combination with the substance of 
 the food, at a temperature at which decay, but neither 
 putrefaction nor fermentation can take place. With the 
 subsequent exclusion of the oxygen and the completion 
 of the decay, every cause which could effect further de- 
 composition of the food is removed. The conditions 
 for putrefaction are rendered insufficient in both cases ; 
 in the one by the removal of the substances susceptible 
 of decay, in the other by the exclusion of the oxygen 
 which would effect it. 
 
 It has been stated (page 316) to be uncertain, whether 
 gluten during its conversion into common yeast, that is, 
 into the insoluble state in which it separates from fer- 
 menting liquids, really combines directly with oxygen. 
 If it does combine with oxygen, then the difference be- 
 tween gluten and ferment would be, that the latter would 
 contain a larger proportion of oxygen. Now it is very 
 difficult to ascertain this, and even their analyses cannot 
 decide the question. Let us consider, for example, the 
 relations of alloxan and alloxantin * to one another. Both 
 of these bodies contain the same elements as gluten. 
 
 * Products of the decomposition of uric acid by nitric acid, consist- 
 ing of carbon, nitrogen, hydrogen, and oxygen. See description, &c. 
 in Webster's Chemistry, pp. 425, 430. 
 
320 FERMENTATION OF BEER. 
 
 although in different proportions. Now they are known 
 to be convertible into each other, by oxygen being ab- 
 sorbed in the one case, and in the other extracted. 
 Both are composed of absolutely the same elements, in 
 equal proportions ; with the single exception, that allox- 
 antin contains 1 equivalent of hydrogen more than al- 
 loxan. 
 
 When alloxantin is treated with chlorine and nitric 
 acid, it is converted into alloxan, into a body, therefore, 
 which is alloxantin minus 1 equivalent of hydrogen. If 
 on the other hand a stream of sulphuretted hydrogen is 
 conducted through alloxan, sulphur is precipitated, and 
 alloxantin produced. It may be said, that in the first 
 case hydrogen is abstracted, in the other added. But it 
 would be quite as simple an explanation, if we consid- 
 ered them as oxides of the same radical ; the alloxan 
 being regarded as a combination of a body composed of 
 C8 N2 H2 OS with 2 equivalents of water, and alloxan- 
 tin as a combination of 3 atoms of water, with a com- 
 pound consisting of C8 N2 H2 07. The conversion of 
 alloxan into alloxantin would in this case result from its 
 eight atoms of oxygen being reduced to seven, while 
 alloxan would be formed out of alloxantin, by its com- 
 bining with an additional atom of oxygen. 
 
 Now, oxides are known which combine with water, 
 and present the same phenomena as alloxan and alloxan- 
 tin. But no compounds of hydrogen are known which 
 form hydrates ; and custom, which rejects all dissim- 
 ilarity until the claim to peculiarity is quite proved, leads 
 us to prefer an opinion, for which there is no further 
 foundation than that o( analogy. The woad {Isatis tinc- 
 toria) and several species of the J^erium contain a sub- 
 stance similar in many respects to gluten, which is 
 
THE BAVARIAN PROCESS. 321 
 
 deposited as indigo blue, when an aqueous infusion of 
 the dried leaves is exposed to the action of the air. 
 Now it is very doubtful whether the blue insoluble indi- 
 go is an oxide of the colorless soluble indigo, or the 
 latter a combination of hydrogen with the indigo blue. 
 Dumas has found the same elements in both, except that 
 the soluble compound contained 1 equivalent of hydro- 
 gen more than the blue. 
 
 In the same manner the soluble gluten may be con- 
 sidered a compound of hydrogen, which becomes fer- 
 ment by losing a certain quantity of this element when 
 exposed to the action of the oxygen of the air under 
 favorable circumstances. At all events, it is certain 
 that oxygen is the cause of the insoluble condition of 
 gluten ; for yeast is not deposited on keeping wine, or 
 during the fermentation of Bavarian beer, unless oxygen 
 has access to the fluid. 
 
 Now whatever be the form in which the oxygen 
 unites with the gluten, — whether it combines directly 
 with it or extracts a portion of its hydrogen, forming 
 water, — the products formed in the interior of the 
 liquid, in consequence of the conversion of the gluten 
 into ferment, will still be the same. Let us suppose 
 that gluten is a compound of another substance with hy- 
 drogen, then this hydrogen must be removed during the 
 ordinary fermentation of must and ivort, by combining 
 with oxygen, exactly as in the conversion of alcohol into 
 aldehyd * by eremacausis. 
 
 In both cases the atmosphere is excluded ; the oxy- 
 
 * A liquid having a peculiar ethereal smell, and obtained by passing 
 the vapor of ether through a large glass tube heated to redness, and 
 by other processes. It consists of carbon 4, hydrogen 4, oxygen 2. 
 Its name is from the Latin, alcohol dehydratus. 
 
322 FERMENTATION OF BEER. 
 
 gen cannot, then, be derived from the air, neither can it 
 be supplied by the elements of water, for it is impossi- 
 ble to suppose that the oxygen will separate from the 
 hydrogen of water, for the purpose of uniting with the 
 hydrogen of gluten, in order again to form water. The 
 oxygen must, therefore, be obtained from the elements 
 of sugar, a portion of which substance must, in order to 
 the formation of ferment, undergo a different decompo- 
 sition from that which produces alcohol. Hence a cer- 
 tain part of the sugar will not be converted into carbonic 
 acid and alcohol, but will yield other products contain- 
 ing less oxygen than sugar itself contains. These pro- 
 ducts, as has already been mentioned, are the cause of 
 the great difference in the qualities of fermented liquids, 
 and particularly in the quantity of alcohol which they 
 contain. 
 
 Must and wort do not, therefore, in ordinary fermen- 
 tation, yield alcohol in proportion to the quantity of 
 sugar which they hold in solution, a part of the sugar 
 being employed in the conversion of gluten into fer- 
 ment, and not in the formation of alcohol. But in the 
 fermentation of Bavarian beer all the sugar is expended 
 in the production of alcohol ; and this is especially the 
 case whenever the transformation of the sugar is not ac- 
 companied by the formation of yeast. 
 
 It is quite certain that in the distilleries of brandy 
 from potatoes, where no yeast is formed, or only a 
 quantity corresponding to the malt which has been add- 
 ed, the proportion of alcohol and carbonic acid obtain- 
 ed during the fermentation of the mash corresponds 
 exactly to that of the carbon contained in the starch. 
 It is also known that the volume of carbonic acid evolv- 
 ed during the fermentation of beet-roots gives no exact 
 
THE BAVARIAN PROCESS. 323 
 
 indication of the proportion of sugar contained in ihenm,. 
 lor less carbonic acid is obtained than the same quantity 
 of pure sugar would yield. 
 
 Beer obtained by the mode of fermentation adopted 
 in Bavaria contains more alcohol, and possesses more 
 intoxicating properties, than that made by the ordinary 
 method of fermentation, when the quantities of malt used 
 are the same. The strong taste of the former beer is 
 generally ascribed to its containing carbonic acid in 
 larger quantity, and in a state of more intimate combi- 
 nation ; but this opinion is erroneous. Both kinds of 
 beer are, at the conclusion of the fermentation, com- 
 pletely saturated with carbonic acid, the one as much 
 as the other. Like all other liquids, they must both 
 retain such a portion of the carbonic acid evolved as 
 corresponds to their power of solution, that is, to their 
 volumes. 
 
 The temperature of the fluid during fermentation has 
 a very important influence on the quantity of alcohol 
 generated. It has been mentioned, that the juice of 
 beet-roots allowed to ferment at from 86^ to 95° (30° 
 to 35° C.) yields no alcohol ; and that afterwards, in the 
 place of the sugar, mannite, a substance incapable of 
 fermentation, and containing very little oxygen, is found, 
 together with lactic acid and mucilage. The formation 
 of these products diminishes in proportion as the tem- 
 perature is lower. But in vegetable juices, containing 
 nitrogen, it is impossible to fix a liniit, where the trans- 
 formation of the sugar is undisturbed by any other pro- 
 cess of decomposition. 
 
 It is known that in the fermentation of Bavarian beer 
 the action of the oxygen of the air, and the low temper- 
 ature, cause complete transformation of the sugar into 
 
324 FERMENTATION OF BEER. 
 
 alcohol ; the cause which would prevent that result, 
 namely, the extraction of the oxygen of part of the sugar 
 by the gluten, in its conversion into ferment, being 
 avoided by the introduction of oxygen from without. 
 
 The quantity of matters in the act of transformation 
 is naturally greatest at the beginning of the fermentation 
 of must and wort ; and all the phenomena which accom- 
 pany the process, such as evolution of gas, and heat, 
 are best observed at that time. These signs of the 
 changes proceeding in the fluid diminish when the 
 greater part of the sugar has undergone decomposition ; 
 but they must cease entirely before the process can be 
 regarded as completed. 
 
 The less rapid process of decomposition which suc- 
 ceeds the violent evolution of gas, continues in wine 
 and beer until the sugar has completely disappeared ; 
 and hence it is observed, that the specific gravity of the 
 liquid diminishes during many months. This slow fer- 
 mentation, in most cases, resembles the fermentation of 
 Bavarian beer, the transformation of the dissolved sugar 
 being in \favt the result of a slow and continued decom- 
 position of the precipitated yeast ; but a complete sep- 
 aration of the azotized substances dissolved in it cannot 
 take place when air is excluded. * 
 
 * The great influence which a rational management of fermenta- 
 tion exercises upon tlie quality of beer is well known in several of the 
 German states. In the grand-duchy of Hesse, for example, a consid- 
 erable premium is offered for the preparation of beer, according to 
 the Bavarian method ; and the premium is to be adjudged to any one 
 who can prove that the beer brewed by him has lain for six months 
 in the store-vats without becoming acid. Hundreds of casks of beer 
 became changed to vinegar before an empirical knowledge of those 
 conditions was obtained, the influence of which is rendered intelligi- 
 ble by the theory. 
 
 Neither alcohol alone, nor hops, nor indeed both together, preserve 
 
MOULDERING OF VEGETABLE SUBSTANCES. 325 
 
 CHAPTER X. 
 
 ON THE MOULDERING OF BODIES. PAPER, BROWN 
 
 COAL, AND MINERAL COAL. 
 
 The decomposition of wood, woody fibre, and all 
 vegetable bodies when subjected to the action of water, 
 and excluded from the air, is termed mouldering. 
 
 Wood or brown coal and mineral coal, are the re- 
 mains of vegetables of a former world ; their appearance 
 and characters show, that they are products of the pro- 
 cesses of decomposition termed decay and putrefac- 
 tion. We can easily ascertain by analysis the manner 
 in which their constituents have been changed, if we sup- 
 pose the greater part of their bulk to have been formed 
 from woody fibre. 
 
 But it is necessary before we can obtain a distinct idea 
 of the manner in which coal is formed, to consider a pe- 
 culiar change which woody fibre suffers by means of 
 moisture, when partially or entirely excluded from the 
 air. 
 
 It is known, that when pure woody fibre, as linen, for 
 
 beer from becoming acid. The better kinds of ale and porter in 
 England are protected from acidity, but at the loss of the interest of 
 an immense capital. They are placed in large closed wooden vessels, 
 the surfaces of which are covered with sand. In these they are 
 allowed to lie for several years, so that they are treated in a manner 
 exactly similar to wine during its ripening. 
 
 A gentle diffusion of air takes place through the pores of the wood» 
 but the quantity of azotized substances being very great in proportioa 
 to the oxygen which enters, they consume it, and prevent its union 
 with the alcohol. But the beer treated in this way does not keep for 
 two months without acidifying, if it be placed in smaller vessels, ta 
 which free access of the air is permitted. — L. 
 
 28 
 
326 DECOMPOSITION OF WOOD, COAL, &C. 
 
 example, is placed in contact with water, considerable 
 heat is evolved, and the substance is converted into a 
 soft friable mass which has lost all coherence. This 
 substance was employed in the fabrication of paper before 
 the use of chlorine, as an agent for bleaching. The rags 
 employed for this purpose were placed in heaps, and it 
 was observed, that on their becoming warm a gas was 
 disengaged, and their weight diminished from 18 to 25 
 per cent. 
 
 When sawdust moistened with water is placed in a 
 closed vessel, carbonic acid gas is evolved in the same 
 manner as when air is admitted. A true putrefaction 
 takes place, the wood assumes a white color, loses its 
 peculiar texture, and is converted into a rotten friable 
 matter. 
 
 The white decayed wood found in the interior of 
 trunks of dead trees which have been in contact with 
 water, is produced in the way just mentioned. 
 
 An analysis of wood of this kind, obtained from the 
 interior of the trunk of an oak, yielded, after having been 
 dried at 212°, 
 
 Carbon, . . 47.11 . . 4814 
 
 Hydrogen, . . 6.31 . . 6.06 
 
 Oxygen, . . 45.31 . . 44.43 
 
 Ashes, . . 1.27 . . • 1.37 
 
 100.00 100.00 
 
 Now, on comparing the proportions obtained from 
 these numbers with the composition of oak wood, ac- 
 cording to the analysis of Gay-Lussac and Thenard, 
 it is immediately perceived, that a certain quantity of 
 carbon has been separated from the constituents of wood, 
 whilst the hydrogen is, on the contrary, increased.* 
 
 * The numbers obtained by the analysis correspond very nearly to 
 
IN CONTACT WITH WATER. 327 
 
 The elements of water have, therefore, become united 
 with the wood, whilst carbonic acid is disengaged by the 
 absorption of a certain quantity of oxygen. 
 
 If the elements of 5 atoms of water and 2 atoms of 
 oxygen be added to the composition of the woody fibre 
 of the oak, and 3 atoms of carbonic acid deducted, the 
 exact formula for white mouldered wood is obtained. 
 
 Wood, C36H22 022 
 
 To this add 5 atoms of water, . . . H 5 O 5 
 
 3 atoms of oxygen, O 3 
 
 C36 H27 O30 
 Subtract from this 3 atoms Carbonic acid, C 3 6 
 
 C33 H27 024 
 
 The process of mouldering is, therefore, one of putre- 
 faction and decay, proceeding simultaneously, in which 
 the oxygen of the air and the component parts of water 
 take part. But the composition of mouldered wood 
 must change according as the access of oxygen is more 
 or less prevented. White mouldered beech wood yield- 
 ed on analysis 47.67 carbon, 5.67 hydrogen, and 46.68 
 oxygen ; this corresponds to the formula C33 H25 024. 
 
 The decomposition of wood assumes, therefore, two 
 different forms, according as the access of the air is free 
 or restrained. In both cases carbonic acid is generated; 
 and in the latter case, a certain quantity of water enters 
 into chemical combination. 
 
 It is highly probable that in this putrefactive process, 
 as well as in all others, the oxygen of the water assists in 
 the formation of the carbonic acid. 
 
 Wood-coal (brown coal of Werner) must have been 
 
 the formula C33 H27 024. (The calculation from this formula gives 
 in 100 parts 47.9 carbon, 6.1 hydrogen, and 46 oxygen.) — L. 
 
328 CONVERSION OF WOOD 
 
 produced by a process of decomposition similar to that 
 of mouldering. But it is not easy to obtain wood-coal 
 suited for analysis, for it is generally impregnated with 
 resinous or earthy substances, by which the composition 
 of those parts which have been formed from woody fibre 
 is essentially changed. 
 
 The wood-coal which forms extensive layers in the 
 Weiterau (a district in Hesse Darmstadt), is distinguish- 
 ed from that found in other places, by possessing the 
 structure of wood unchanged, and by containing no bitu- 
 minous matter. This coal was subjected to analysis, a 
 piece being selected upon which the annual circle could 
 be counted. It was obtained from the vicinity of Lau- 
 bach ; 100 parts contained 
 
 Carbon, 57.28 
 
 Hydrogen, ..... 6.03 
 
 Oxygen, ..... 36.10 
 
 Ashes, 0.59 
 
 100.00 
 
 The large amount of carbon, and small quantity of 
 oxygen, constitute the most obvious difference between 
 this analysis and that of wood. It is evident that the 
 wood which has undergone the change into coal must 
 have parted with a certain portion of its oxygen. The 
 proportion of these numbers is expressed by the formu- 
 la C33 H21 016. (The calculation gives 57.5 carbon 
 and 5.98 hydrogen.) 
 
 When these numbers are compared with those obtain- 
 ed by the analysis of oak, it would appear that the brown 
 coal was produced from woody fibre by the separation of 
 one equivalent of hydrogen, and the elements of three 
 equivalents of carbonic acid. 
 
INTO BROWN OR WOOD COAL. 329 
 
 1 atom wood, C36 H22 022 
 
 Minus 1 atom hydrogen and 3 atoms carbonic acid, C 3H 1 O 6 
 
 Wood-Coal. C33 H21 OIG 
 
 All varieties of wood-coal, from whatever strata they 
 may be taken, contain more hydrogen than wood does, 
 and less oxygen than is necessary to form water with this 
 hydrogen ; consequently they must all be produced by 
 the same process of decomposition. The excess of hy- 
 drogen is either hydrogen of the wood which has re- 
 mained in it unchanged, or it is derived from some ex- 
 terior source. The analysis of wood-coal from Ringkuhl, 
 near Cassel, where it is seldom found in pieces with the 
 structure of wood, gave, when dried at 212°, 
 
 Carbon, 
 
 62.60 
 
 63.83 
 
 Hydrogen, 
 
 . 5.02 
 
 . 4 80 
 
 Oxygen, . 
 
 26.52 
 
 25.51 
 
 Ashes, 
 
 . 5.86 
 
 . 5.86 
 
 100.00 100.00 
 
 The proportions derived from these numbers corre- 
 spond very closely to the formula, Co2 Hi 5 09, or they 
 represent the constituents of wood, from which the ele- 
 ments of carbonic acid, water, and 2 equivalents hydro- 
 gen have been separated. 
 
 C36 H22 022 = Wood. 
 Subtract C 4 H 7 013 = 4 atoms carbonic acid -f- 5 atoms of water 
 -f-2 atoms of hydrogen. 
 
 C32 H15 = Wood-Coal from Ringkuhl. 
 
 The formation of both these specimens of wood-coal 
 appears from these formulae to have taken place under 
 circumstances which did not entirely exclude the action 
 of the air, and consequent oxidation and removal of a 
 certain quantity of hydrogen. Now the Laubacher coal 
 28* 
 
330 CONVERSION OF WOOD 
 
 is covered with a layer of basalt, and the coal of Ring- 
 kuhl was taken from the lowest seam of layers, which 
 possess a thickness of from 90 to 120 feet ; so that both 
 may be considered as well protected from the air. 
 
 During the formation of brown coal, the elements of 
 carbonic acid have been separated from the wood either 
 alone, or at the same time with a certain quantity of 
 water. It is quite possible that the difference in the pro- 
 cess of decomposition may depend upon the high tem- 
 perature and pressure under which the decomposition 
 took place. At least, a piece of wood assumed the 
 character and appearance of Laubacher coal, after being 
 kept for several weeks in the boiler of a steam-engine, 
 and had then precisely the same composition. The 
 change in this case was effected in water, at a tempera- 
 ture of from 334° to 352° F. (150°— 160° C), and 
 under a corresponding pressure. The ashes of the wood 
 amounted to 0,51 per cent. ; a little less, therefore, than 
 those of the Laubacher coal ; but this must be ascribed 
 to the peculiar circumstances under which it was formed. 
 The ashes of plants examined by Berthier amounted 
 always to much more than this. 
 
 The peculiar process by which the decomposition of 
 these extinct vegetables has been effected, namely, a dis- 
 engagement of carbonic acid from their substance, ap- 
 pears still to go on at great depths in all the layers of 
 wood-coal. At all events it is remarkable that springs 
 impregnated with carbonic acid occur in many places, in 
 the country between Meissner, in the electorate of Hesse, 
 and the Eifel, which are known to possess large layers of 
 wood-coal. These springs of mineral water are pro- 
 duced on the spot at which they are found ; the springs 
 ;of common water meeting with carbonic acid during 
 Iheir ascent, and becoming impregnated with it. 
 
INTO BROWN OR WOOD COAL. 331 
 
 In the vicinity of the layers of wood-coal at Salzhau- 
 sen (Hesse Darmstadt) an excellent acidulous spring 
 of this kind existed a few years ago, and supplied all 
 the inhabitants of that district ; but it was considered 
 advantageous to surround the sides of the spring with 
 sandstone, and the consequence was, that all the outlets 
 to the carbonic acid were closed, for this gas generally 
 gains access to the water from the sides of the spring. 
 From that time to the present this valuable mineral 
 water has disappeared, and in its place is found a spring 
 of common water. 
 
 Springs of water impregnated with carbonic acid 
 occur at Schvvalheim, at a very short distance from the 
 layers of wood coal at Dorheim. M. Wilhehni ob- 
 served some time since, that they are formed of com- 
 mon spring water which ascends from below, and of 
 carbonic acid which issues from the sides of the spring. 
 The same fact has been shown to be the case in the 
 famed Fachinger spring, by M. Schapper. 
 
 The carbonic acid gas from the springs in the Eifel 
 is, according to Bischof^ seldom mixed with nitrogen 
 or oxygen, and is probably produced in a manner simi- 
 lar to that just described. At any rate the air does not 
 appear to take any part in the formation of these acidu- 
 lous springs. Their carbonic acid has evidently not 
 been formed either by a combustion at high or low 
 temperatures ; for if it were so, the gas resulting from 
 the combustion would necessarily be mixed with | of 
 nitrogen, but it does not conlain a trace of this ele- 
 ment. The bubbles of gas which escape from these 
 springs are absorbed by caustic potash, with the excep- 
 tion of a residuum too small to be appreciated. 
 
 The wood-coal of Dorheim and Salzhausen must have 
 
632 CONVERSION OF WOOD 
 
 been formed in the same way as that of the neighbour- 
 ing village of Laubach ; and since the latter contains 
 the exact elements of woody fibre, minus a certain 
 quantity of carbonic acid, its composition indicates very 
 plainly the manner in which it has been produced. 
 
 The coal of the upper bed is subjected to an inces- 
 sant decay by the action of the air, by means of which 
 its hydrogen is removed in the same manner as in the 
 decay of wood. This is recognised by the way in 
 which it burns, and by the formation of carbonic acid in 
 the mines. 
 
 The gases which are formed in mines of wood-coal, 
 and cause danger in their working, are not combustible 
 or inflammable as in mines of mineral coal ; but they 
 consist generally of carbonic acid gas, and are very sel- 
 dom intermixed with combustible gases. 
 
 Wood-coal from the middle bed of the strata at 
 Ringkuhl gave on analysis 65.40 — 64.01 carbon and 
 4.75 — 4.76 * hydrogen ; the proportion of carbon 
 here is the same as in specimens procured from greater 
 depths, but that of the hydrogen is much less. 
 
 Wood and mineral coal are always accompanied by 
 iron pyrites (sulphuret of iron) or zinc blende (sulphu- 
 ret of zinc) ; which minerals are still formed from salts 
 of sulphuric acid, with iron or zinc, during the putre- 
 faction of all vegetable matter. It is possible that ihe 
 oxygen of the sulphates in the layers of wood-coal is 
 the means by which the removal of the hydrogen is 
 effected, since wood-coal contains less of this element 
 than wood. 
 
 * The analysis of brown coal from Ringkuhl, as well as all the analy- 
 ses of the same substance given in this work, have been executed in 
 this laboratory by M. Kiihncrt of Cassel. — L. 
 
INTO MINERAL COAL. 333 
 
 According to the analysis of Richardson and Rcg- 
 nault, the composition of the combustible materials in 
 splint coal from Newcastle, and cannel coal from Lan- 
 cashire, is expressed by the formula C24H13 0. 
 When this is compared with the composition of woody 
 fibre, it appears that these coals are formed from its 
 elements, by the removal of a certain quantity of carbu- 
 retted hydrogen and carbonic acid in the form of com- 
 bustible oils. The composition of both of these coals 
 is obtained by the subtraction of 3 atoms of carburetted 
 hydrogen, 3 atoms of water, and 9 atoms of carbonic 
 acid from, the formula of wood. 
 
 3 atoms of carburetted hydrogen, C 3 H 6 
 3 atoms of water, . . . H 3 O 3 
 9 atoms of carbonic acid, . C 9 O 18 
 
 C 36 H 22 022 = wood 
 C12H9 02I 
 
 Mineral coal, C 24 H 13 O 
 Carburetted hydrogen generally accompanies all min- 
 eral coal ; other varieties of coal contain volatile oils 
 which may be separated by distillation with water. 
 (Rcichenbach.) The origin of naptha is owing to a 
 similar process of decomposition. Caking coal from 
 Caresfield, near Newcastle, contains the elements of 
 cannel coal, minus the constituents of olefiant gas C 4 
 H4. 
 
 The inflammable gases which stream out of clefts in 
 the strata of mineral coal, or in rocks of the coal forma- 
 tions, always contain carbonic acid, according to a 
 recent examination by Bischnff, and also carburetted 
 hydrogen, nitrogen, and olefiant gas ; the last of which 
 had not been observed, until its existence in these gases 
 was pointed out by Bischoff. The analysis of Jire- 
 damp after it had been treated with caustic potash 
 showed its constituents to be, 
 
334 rORMATION OF COAL. 
 
 Gas from an 
 
 Gerhard's pas- 
 
 Gas from a 
 
 al)amloneJ 
 
 sage near Lu- 
 
 mine near 
 
 mine near 
 
 isenlbal. 
 
 Liekwege. 
 
 Wallesweiler. 
 
 
 
 Vol. 
 
 Vol. 
 
 Vol. 
 
 n, 97 36 
 
 83.08 
 
 89.10 
 
 G.32 
 
 1.08 
 
 16.11 
 
 2.32 
 
 14.94 
 
 4.79 
 
 Olefiant gas, 
 Nitrogen gas, 
 
 100.00 100.00 100 00 
 
 The evolution of these gases proves that changes are 
 constantly proceeding in the coal. 
 
 It is obvious from this, that a continual removal of 
 oxygen in the form of carbonic acid is effected from 
 layers of wood-coal, in consequence of which the wood 
 must approach gradually to the composition of mineral 
 coal. Hydrogen, on the contrary, is disengaged from 
 the constituents of mineral coal in the form of a com- 
 pound of carbo-hydrogen ; a complete removal of all 
 the hydrogen would convert coal into anthracite. 
 
 The formula C 36 H 22 O 22, which is given for 
 wood, has been chosen as the empirical expression of 
 the analysis, for the purpose of bringing all the transfor- 
 mations which woody fibre is capable of undergoing 
 under one common point of view. 
 
 Now, although the correctness of this formula must 
 be doubted, until we know with certainty the true con- 
 stitution of woody fibre, this cannot have the smallest 
 influence on the account given of the changes to which 
 woody fibre must necessarily be subjected in order to 
 be converted into wood or mineral coal. The theo- 
 retical expression refers to the quantity, the empirical 
 merely to the relative propoition 'in which the elements 
 of a body are united. Whatever form the first may 
 assume, the empirical expression must always remain 
 unchanged. 
 
POISONS, CONTAGIONS, MIASMS. 335 
 
 CHAPTER XL 
 
 ON POISONS, CONTAGIONS, AND MIASMS. 
 
 A GREAT many chemical compounds, some derived 
 from inorganic nature, and others formed in animals and 
 plants, produce peculiar changes or diseases in the living 
 animal organism. They destroy the vital functions of 
 individual organs ; and when their action attains a certain 
 degree of intensity, death is the consequence. 
 
 The action of inorganic compounds, such as acids, al- 
 kalies, metallic oxides, and salts, can in most cases be 
 easily explained. They either destroy the continuity of 
 particular organs, or they enter into combination with 
 their substance. The action of sulphuric, muriatic, and 
 oxalic acids, hydrate of potash, and all those substances 
 which produce the direct destruction of the organs with 
 which they come into contact, may be compared to a 
 piece of iron, which can cause death by inflicting an in- 
 jury on particular organs, either when heated to redness, 
 or when in the form of a sharp knife. Such substances 
 are not poisons in the limited sense of the word, for their 
 injurious action depends merely upon their condition. 
 
 The action of the proper inorganic poisons is owing, 
 in most cases, to the formation of a chemical compound 
 by the union of the poison with the constituents of the 
 organ upon which it acts ; it is owing to an exercise of a 
 chemical affinity more powerful than the vitality of the 
 organ. 
 
 It is well to consider the action of inorganic substan- 
 ces in general, in order to obtain a clear conception of 
 the mode of action of those which are poisonous. We 
 
336 POISONS, CONTAGIONS, MIASMS. 
 
 find tliat certain soluble conripounds, when presented to 
 difTerenl parts of tlie body, are absorbed by the blood, 
 whence they are again eliniiiialed by the organs of secre- 
 tion, either in a changed or in an uiiciianged state. 
 
 Iodide of yotiiHsium^ sulpho-cyanurci of potassium, 
 ferro-cyanuret of 'potassium, chlorate of potash, silicate 
 of potash, and all salts with alkaline bases, when adtnin- 
 islcred internally to man and animals in dilute solutions, 
 or applied externally, may be agiin (lel(;cle(l in ihe blood, 
 sweat, chyle, gall, and s|)jenic veins; but all of them are 
 finally excreted from the body through the urinary pas- 
 sages. 
 
 Each of these substances, in its transit, produces a pe- 
 culiar distiu'bance in the organism, — in other words, they 
 exercise a rrjedicinal action upon it, but they themselves 
 suffer no decomposition. If any of these substances en- 
 ter into combination with any part of the body, the union 
 cannot be of a j)ermanent kind ; for their reappearance 
 in the urine shows that any compounds thus formed must 
 have been again decomposed by the vital processes. 
 
 Neutral citrates, acetates, and tartrates of the alkalies, 
 suffer change in their passage through the organism. 
 Their bases can indeed be detected in the urine, but the 
 acids have entirely disappeared, and are replaced by car- 
 bonic acid which has united with the bases. {(Jilbert 
 Blane and WohJer.) 
 
 The conversion of these salts of organic acids into car- 
 bonates, indicates that a considerable quantity of oxygen 
 must have united with their elements. In order to con- 
 vert I eijuivalent of acetate of potash into the carbonate 
 of the same base, 8 eijuivaletits of oxygen must combine 
 with it, of which either 2 or 4 equivalents (according as 
 an acid or neutral salt is produced) remain in combina- 
 
EFFECTS OF SALTS ON THK ORGANISM. 337 
 
 tion with tlic alkali ; whilst the reinaininj; G or ^ equiva- 
 lents are disenifaged as free carbonic acid. There is no 
 evidence presented by the organism itself, to which these 
 salts have been administered, that any of its ))r()|)cr con- 
 stituents have yielded so great a quantity of oxygen as 
 is necessary for tlu.'ir conversion into carbonates. 'J'heir 
 oxidation can, therefore, only be ascrilied to the oxygen 
 of the air. 
 
 During the passage of these salts through the lungs, 
 their acids take part in the peculiar process of erema- 
 causis which proceeds in that organ ; a certain quantity 
 of the oxygen gas inspired unites with their constituents, 
 and converts their hydrogen into water, and their carbon 
 into carbonic acid. J'art of this latter product (1 or 2 
 equivalents) remains in combination with the alkaline 
 base, forming a salt which suffers no further change by 
 the process of oxidation ; and it is this salt which is sep- 
 arated by the kidneys or liver. 
 
 It is jnanifest, that the presence of these organic salts 
 in the blood must |)roduce a change in the process of 
 respiration. A part of the oxygen inspired, which usual- 
 ly combines with the constituents of the blood, must^ 
 when they are present, cotnbine with their acids, and 
 thus be prevented from performing its usual oOice. 'J'he 
 imtiK.'diale consequence of this must he the formation of 
 arterial blood in less (|uantiiy, or in other words, iIk; pro- 
 cess of respiration must be retarded. 
 
 Neutral acetates, tartrates, and cilrales |)laced in con- 
 tact with the air, and at the same time with animal or 
 vegetable bodies in a state of eremacausis, produce ex- 
 actly the same effects as we have described them to pro- 
 duc;(.' iu the lungs. They participate in (he |)rocess of 
 decay, and are converted into carbonates just as in the 
 29 
 
338 POISONS, CONTAGIONS, MIASMS. 
 
 living body. If impure solutions of these salts in water 
 are left exposed to the air for any length of time, their 
 acids are gradually decomposed, and at length entirely 
 disappear. 
 
 Free mineral acids, or organic acids which are not 
 volatile, and salts of mineral acids with alkaline bases, 
 completely arrest decay when added to decaying matter 
 in sufficient quantity ; and when their quantity is small, 
 the process of decay is protracted and retarded. They 
 produce in living bodies the same phenomena as the neu- 
 tral organic salts, but their action depends upon a differ- 
 ent cause. 
 
 The absorption by the blood of a quantity of an inor- 
 ganic salt sufficient to arrest the process of eremacausis 
 in the lungs, is prevented by a very remarkable property 
 of all animal membranes, skin, cellular tissue, muscular 
 fibre, &c. ; namely, by their incapability of being per- 
 meated by concentrated saline solutions. It is only 
 when these solutions are diluted to a certain degree with 
 water that they are absorbed by animal tissues. 
 
 A dry bladder remains more or less dry in saturated 
 solutions of common salt, nitre, ferro-cyanuret of potas- 
 sium, sulpho-cyanuret of potassium, sulphate of magne- 
 sia, chloride of potassium, and sulphate of soda. These 
 solutions run off its surface in the same manner as water 
 runs from a plate of glass besmeared with tallow. 
 
 Fresh flesh, over which salt has been strewed, is 
 found after 24 hours' swimming in brine, although not a 
 drop of water has been added. The water has been 
 yielded by muscular fibre itself, and having dissolved the 
 salt in immediate contact with it, and thereby lost the 
 power of penetrating animal substances, it has on this 
 account sej)arated from the flesh. The water still re- 
 
EFFECTS OF SALTS ON THE ORGANISM. 339 
 
 tained by the flesh contains a proportionally small quan- 
 tity of salt, having that degree of dilution at which a 
 saline fluid is capable of penetrating animal substances. 
 
 This property of animal tissues is taken advantage of 
 in domestic economy, for the purpose of removing so 
 much water from meat, that a sufficient quantity is not 
 left to enable it to enter into putrefaction. 
 
 In respect of this physical property of animal tissues, 
 alcohol resembles the inorganic salts. It is incapable of 
 moistening, that is, of penetrating animal substances, and 
 possesses such an affinity for water as to extract it from 
 moist substances. 
 
 When a solution of a salt, in a certain degree of di- 
 lution, is introduced into the stomach, it is absorbed ; 
 but a concentrated saline solution, in place of being it- 
 self absorbed, extracts water from the organ, and a vio- 
 lent thirst ensues. Some interchange of water and salt 
 takes place in the stomach : the coats of this viscus 
 yield water to the solution, a part of which having pre- 
 viously become sufficiently diluted is, on the other hand, 
 absorbed. But the greater part of the concentrated so- 
 lution of salt remains unabsorbed, and is not removed 
 by the urinary passages ; it consequently enters the in- 
 testines and intestinal canal, where it causes a dilution of 
 the solid substance deposited there, and thus acts as a 
 purgative. 
 
 Each of the salts just mentioned possesses this purga- 
 tive action, which depends on a physical property shared 
 by all of them ; but besides this they exercise a medi- 
 cinal action, because every part of the organism with 
 which they come in contact absorbs a certain quantity of 
 them. 
 
 The composition of the salts has nothing to do with 
 
340 POISONS, CONTAGIONS, MIASMS. 
 
 their purgative action ; it is quite a matter of indiffer- 
 ence as far as the mere production of this action is con- 
 cerned (not as to its intensity), whether the base be pot- 
 ash or soda, or in many cases hme and magnesia ; and 
 whether the acid be phosphoric, sulphuric, nitric, or hy- 
 drochloric. 
 
 Besides these salts, the action of which does not de- 
 pend upon their power of entering into combination 
 with the component parts of the organism ; there is a 
 large class of others which, when introduced into the 
 living body, effect changes of a very different kind, and 
 produce diseases or death, according to the nature of 
 these changes, without effecting a visible lesion of any 
 organs. 
 
 These are the true inorganic poisons, the action of 
 which depends upon their power of forming permanent 
 compounds with the substance of the membranes, and 
 muscular fibre. 
 
 Salts of lead, iron, bismuth, copper, and mercury, be- 
 long to this class. 
 
 When solutions of these salts are treated with a suffi- 
 cient quantity of albumen, milk, muscular fibre, and an- 
 imal membranes, they enter into combination with those 
 substances, and lose their own solubility ; while the 
 water in which they were dissolved loses all the salt 
 which it contained. 
 
 The salts of alkaline bases extract water from animal 
 substances ; whilst the salts of the heavy metallic oxides 
 are, on the contrary, extracted from the water, for they 
 enter into combination with the animal matters. 
 
 Now, when these substances are administered to an 
 animal, they lose their solubility by entering into combi- 
 nation with the membranes, cellular tissue, and muscular 
 
INORGANIC POISONS. 341 
 
 fibre ; but in very few cases can they reach the blood. 
 All experiments instituted for the purpose of determin- 
 ing whether they pass into the urine have failed to detect 
 them in that secretion. In fact, during their passage 
 through the organism, they come into contact with many 
 substances by which they are retained. 
 
 The action of corrosive sublimate and arsenious acid 
 is very remarkable in this respect. It is known that 
 these substances possess, in an eminent degree, the 
 property of entering into combination with all parts of 
 animal and vegetable bodies, rendering them at the same 
 time insusceptible of decay or putrefaction. Wood and 
 cerebral substance are both bodies which undergo change 
 with great rapidity and facility when subject to the influ- 
 ence of air and water ; but if they are digested for some 
 time with arsenious acid or corrosive sublimate, they 
 may subsequently be exposed to all the influence of the 
 atmosphere without altering in color or appearance. 
 
 It is further known that those parts of a body, which 
 come in contact with these substances during poisoning, 
 and which therefore enter into combination with them, 
 do not afterwards putrefy, so that there can be no doubt 
 regarding the cause of their poisonous qualities. 
 
 It is obvious that if arsenious acid and corrosive sub- 
 limate are not prevented by the vital principle from en- 
 tering into combination with the component parts of the 
 body, and consequently from rendering them incapable 
 of decay and putrefaction, they must deprive the organs 
 of the principal property which appertains to their vital 
 condition, viz. that of suffering and effecting transfor- 
 mations ; or, in other words, organic life must be de- 
 stroyed. If the poisoning is merely superficial, and the 
 quantity of the poison so small that only individual parts 
 29* 
 
342 POISONS, CONTAGIONS, MIASMS. 
 
 of the body which are capable of being regenerated 
 have entered into combination with it, then eschars are 
 produced, — a phenomenon of a secondary kind, — the 
 compounds of the dead tissues with the poison being 
 thrown off by the healthy parts. From these considera- 
 tions it may readily be inferred that all internal signs of 
 poisoning are variable and uncertain ; for cases may 
 happen, in which no apparent indication of change can 
 be detected by simple observations of the parts, be- 
 cause, as has been already remarked, death may occur 
 without the destruction of any organs. 
 
 When arsenious acid is administered in solution, it 
 may enter into the blood. If a vein is exposed and 
 surrounded with a solution of this acid, every blood- 
 globule will combine with it, that is, will become poi- 
 soned. 
 
 The compounds of arsenic, which have not the 
 property of entering into combination with the tissues 
 of the organism, are without influence on life, even in 
 large doses. Many insoluble basic salts of arsenious 
 acid are known not to be poisonous. The substance 
 called alkargen, discovered by Bunstn., which contains 
 a very large quantity of arsenic, and approaches very 
 closely in composition to the organic arsenious com- 
 pounds found in the body, has not the slightest injurious 
 action upon the organism. 
 
 These considerations enable us to fix with tolerable 
 certainty the limit at which the above substances cease 
 to act as poisons. For since their combination with 
 organic matters must be regulated by chemical laws, 
 death will inevitably result, when the organ in contact 
 with the poison finds sufficient of it to unite with atom 
 for atom ; whilst if the poison is present in smaller 
 
INORGANIC POISONS. 343 
 
 quantity, a part of the organ will retain its vital func- 
 tions. 
 
 According to the experiments of iV/w/f/er,* the equiv- 
 alent in which fibrin combines with muriatic acid, and 
 with the oxides of lead and copper, is expressed by the 
 number 6361. It may be assumed therefore approxi- 
 matively, that a quantity of fibrin corresponding to the 
 number 6361 combines with 1 equivalent of arsenious 
 acid, or 1 equivalent of corrosive sublimate. 
 
 When 6361 parts of anhydrous fibrin are combined 
 with 30,000 parts of water, it is in the state in which it 
 is contained in muscular fibre or blood in the human 
 body. 100 grains of fibrin in this condition would form 
 a neutral compound of equal equivalents with 3^^ grains 
 of arsenious acid, and 5 grains of corrosive sublimate. 
 
 The atomic weight of the albumen of eggs and of 
 the blood deduced from the analysis of the compound 
 which it forms with oxide of silver is 7447, and that of 
 aninial gelatin 5652. 
 
 100 grains of albumen containing all the water with 
 which it is combined in the living body, should conse- 
 quently combine with 1| grain of arsenious acid. 
 
 These proportions, which may be considered as the 
 highest which can be adopted, indicate the remarkably 
 high atomic weights of animal substances, and at the 
 same time teach us what very small quantities of ar- 
 senious acid or corrosive sublimate are requisite to pro- 
 duce deadly effects. 
 
 All substances administered as antidotes in cases of 
 poisoning, act by destroying the power which arsenious 
 acid and corrosive sublimate possess, of entering into 
 
 * PoggendorfF's Annaien, Band xl. S. 259. 
 
344 POISONS, CONTAGIONS, MIASMS. 
 
 combination with animal matters, and of thus acting as 
 poisons. Unfortunately no other body surpasses them 
 in that power, and the compounds which they forn) can 
 only be broken up by affinities so energetic, that their 
 action is as injurious as that of the above-named poisons 
 themselves. The duty of the physician consists, there- 
 fore, in his causing those parts of the poison which may 
 be free and still uncombined, to enter into combination 
 with some other body, so as to produce a compound in- 
 capable of being decomposed or digested in the same 
 conditions. Hydrated peroxide of iron is an invaluable 
 substance for this purpose. 
 
 When the action of arsenious acid or corrosive sub- 
 limate is confined to the surface of an organ, those parts 
 only are destroyed which enter into combination with 
 it ; an eschar is formed which is gradually thrown off. 
 
 Soluble salts of silver would be quite as deadly a 
 poison as corrosive sublimate, did not a cause exist in 
 the human body by which their action is prevented, un- 
 less their quantity is very great. This cause is the 
 presence of common salt in all animal liquids. Nitrate 
 of silver, it is well known, combines with animal sub- 
 stances, in the same manner as corrosive sublimate, and 
 the compounds formed by both are exactly similar in 
 the character of being incapable of decay or putrefac- 
 tion. 
 
 When nitrate of silver in a state of solution is applied 
 to skin or muscular fibre, it combines with them instan- 
 taneously ; animal substances dissolved in any liquid are 
 precipitated by it, and rendered insoluble, or as it is 
 usually termed, they are coagulated. The compounds 
 thus formed are colorless, and so stable that they cannot 
 be decomposed by other powerful chemical agents. 
 
ORGANIC POISONS. 345 
 
 They are blackened by exposure to light, like all other 
 compounds of silver, in consequence of a part of the 
 oxide of silver which they contain being reduced to the 
 metallic state. Parts of the body which have united with 
 salts of silver, no longer belong to the living organism, 
 for their vital functions have been arrested by combina- 
 tion with oxide of silver ; and if they are capable of 
 being reproduced, the neighbouring living structures 
 throw them off in the form of an eschar. 
 
 When nitrate of silver is introduced into the stomach, 
 it meets with common salt and free muriatic acid ; and if 
 its quantity is not too great, it is immediately converted 
 into chloride of silver, — a substance which is absolutely 
 insoluble in pure water. In a solution of salt or muriatic 
 acid, however, chloride of silver does dissolve in ex- 
 tremely minute quantity ; and it is this small part which 
 exercises a medicinal influence when nitrate of silver is 
 administered ; the remaining chloride of silver is elimin- 
 ated from the body in the ordinary way. Solubility is 
 necessary to give efficacy to any substance in the human 
 body. 
 
 The soluble salts of lead possess many properties in 
 common with the salts of silver and mercury ; but all 
 compounds of lead with organic matters are capable of 
 decomposition by dilute sulphuric acid. The disease 
 called painter's colic is unknown in all manufactories of 
 white lead in which the workmen are accustomed to take 
 as a preservative sulphuric acid lemonade (a solution of 
 sugar rendered acid by sulphuric acid). 
 
 The organic substances which have combined in the 
 living body with metallic oxides or metallic salts, lose 
 their property of imbibing water and retaining it, without 
 at the same time being rendered incapable of permitting 
 
346 POISONS, CONTAGIONS, MIASMS. 
 
 liquids to penetrate through their pores. A strong con- 
 traction and shrinking of a surface is the general effect 
 of contact with these metallic bodies. But corrosive 
 sublimate, and several of the salts of lead, possess a pe- 
 culiar property, in addition to those already mentioned. 
 When they are present in excess, they dissolve the first 
 formed insoluble compounds, and thus produce an effect 
 quite the reverse of contraction, namely, a softening of 
 the part of the body on which they have acted. 
 
 Salts of oxide of copper, even when in combination 
 with the most powerful acids, are reduced by many vege- 
 table substances, particularly such as sugar and honey, 
 either into metallic copper, or into the red suboxide, 
 neither of which enters into combination with animal 
 matter. It is well known that sugar has been long em- 
 ployed as the most convenient antidote for poisoning by 
 copper. 
 
 With respect to some other poisons, namely, hydro- 
 cyanic acid and the organic bases strychnia and brucia, 
 we are acquainted with no facts calculated to elucidate 
 the nature of their action. It may, however, be pre- 
 sumed with much certainty, that experiments upon their 
 mode of action on different animal substances, would 
 very quickly lead to the most satisfactory conclusions, re- 
 garding the cause of their poisonous effects. 
 
 There is a peculiar class of substances, which are 
 generated during certain processes of decomposition, and 
 which act upon the animal economy as deadly poisons, 
 not on account of their power of entering into combina- 
 tion with it, or by reason of iheir containing a poisonous 
 material, but solely by virtue of their peculiar condition. 
 
 In order to attain to a clear conception of the mode of 
 action of these bodies, it is necessary to call to mind the 
 
ORGANIC POISONS. 347 
 
 cause on which we have shown the phenomena of fer- 
 mentation, decay, and putrefaction to depend. 
 
 This cause may be expressed by the following law, 
 long since proposed by La Place and Berthollet, although 
 its truth with respect to chemical phenomena has only 
 lately been proved. ".^3 molecule set in motion by any 
 power can impart its own motion to another molecule with 
 which it may he in contact." 
 
 This is a law of dynamics, the operation of which is 
 manifest in all cases, in which the resistance (force, 
 affinity, or cohesion) opposed to the motion is not suf- 
 ficient to overcome it. 
 
 We have seen that ferment or yeast is a body in the 
 state of decomposition, the atoms of which, consequenlly, 
 are in a state of motion or transposition. Yeast placed 
 in contact with sugar, communicates to the elements of 
 that compound the same state, in consequence of which, 
 the constituents of the sugar arrange themselves into new 
 and simpler forms, namely, into alcohol and carbonic 
 acid. In these new compounds, the elements are united 
 together by stronger affinities than they were in the sugar, 
 and therefore under the conditions in which they were 
 produced further decomposition is arrested. 
 
 We know, also, that the elements of sugar assume 
 totally different arrangements, when the substances which 
 excite their transposition are in a different state of de- 
 composition from the yeast just mentioned. Thus, when 
 sugar is acted on by rennet or putrefying vegetable 
 juices, it is not converted into alcohol and carbonic acid, 
 but into lactic acid, mannite, and gum. 
 
 Again, it has been shown, that yeast added to a solu- 
 tion of pure sugar gradually disappears, but that when 
 added to vegetable juices which contain gluten as well as 
 
348 POISONS, CONTAGIONS, MIASMS. 
 
 sugar, it is reproduced by the decomposition of the for- 
 mer substance. 
 
 The yeast with which these liquids are made to fer- 
 ment, has itself been originally produced from gluten. 
 
 The conversion of gluten into yeast in these vegeta- 
 ble juices is dependent on the decomposition (fermenta- 
 tion) of sugar ; for, when the sugar has completely 
 disappeared, any gluten which may still remain in the 
 liquid, does not suffer change from contact with the 
 newly-deposited yeast, but retains all the characters of 
 gluten. 
 
 Yeast is a product of the decomposition of gluten ; 
 but it passes into a second stage of decomposition when 
 in contact with water. On account of its being in this 
 state of further change, yeast excites fermentation in a 
 fresh solution of sugar, and if this second saccharine 
 fluid should contain gluten, (should it be wort, for ex- 
 ample,) yeast is again generated in consequence of the 
 transposition of the elements of the sugar exciting a 
 similar change in this gluten. 
 
 After this explanation, the idea that yeast reproduces 
 itself as seeds reproduce seeds, cannot for a moment be 
 entertained. 
 
 From the foregoing facts it follows, that a body in the 
 act of decomposition (it may be named the exciter), 
 added to a mixed fluid in which its constituents are con- 
 tained, can reproduce itself in that fluid, exactly in the 
 same manner as new yeast is produced when yeast is 
 added to liquids containing gluten. This must be more 
 certainly eflected when the liquid acted upon contains 
 the body by the metamorphosis of which the exciter has 
 been originally formed. 
 
 It is also obvious, that if the exciter be able to impart 
 
PUTRID POISONS. 349 
 
 its own state of transformation to one only of the com- 
 ponent parts of the mixed hquid acted upon, its own re- 
 production may be the consequence of the decomposi- 
 tion of this one body. 
 
 This law may be applied to organic substances form- 
 ing part of the animal organism. We know that all the 
 constituents of these substances are formed from the 
 blood, and that the blood by its nature and constitution 
 is one of the most complex of all existing matters. 
 
 Nature has adapted the blood for the reproduction of 
 every individual part of the organism ; its principal 
 character consists in its component parts being subor- 
 dinate to every attraction. These are in a perpetual 
 state of change or transformation, which is efiected in 
 the most various ways through the influence of the dif- 
 ferent organs. 
 
 The individual organs, such as the stomach, cause all 
 the organic substances conveyed to them which are ca- 
 pable of transformation to assume new forms. The 
 stomach compels the elements of these substances to 
 unite into a compound fitted for the formation of the 
 blood. But the blood possesses no power of causing 
 transformations ; on the contrary, its principal character 
 consists in its readily suffering transformations ; and no 
 other matter can be compared in this respect with it. 
 
 Now it is a well-known fact, that when blood, cere- 
 bral substance, gall, pus, and other substances in a state 
 of putrefaction, are laid upon fresh wounds ; vomiting, 
 debility, and at length death, are occasioned. It is also 
 well known that bodies in anatomical rooms frequently 
 pass into a state of decomposition which is capable of 
 imparting itself to the hving body, the smallest cut with 
 30 
 
350 POISONS, CONTAGIONS, MIASMS. 
 
 a knife which has been used in their dissection producing 
 in these cases dangerous consequences. 
 
 The poison of bad sausages belongs to this class of 
 noxious substances. 
 
 Several hundred cases are known in which death has 
 occurred from the use of this kind of food. 
 
 In Wiirtemburg especially, these cases are very fre- 
 quent, for there the sausages are prepared from very va- 
 rious materials. 
 
 Blood, liver, bacon, brains, milk, meal, and bread, 
 are mixed together with salt and spices ; the mixture is 
 then put into bladders or intestines, and after being 
 boiled is smoked. 
 
 When these sausages are well prepared, they may be 
 preserved for months, and furnish a nourishing, savoury 
 food ; but when the spices and salt are deficient, and 
 particularly when they are smoked too late or not suffi- 
 ciently, they undergo a peculiar kind of putrefaction 
 which begins at the centre of the sausage. Without 
 any appreciable escape of gas taking place, they become 
 paler in color, and more soft and greasy in those parts 
 which have undergone putrefaction, and they are found 
 to contain free lactic acid or lactate of ammonia ; pro- 
 ducts which are universally formed during the putrefac- 
 tion of animal and vegetable matters. 
 
 The cause of the poisonous nature of these sausages 
 was ascribed at first to hydrocyanic acid, and afterwards 
 to sebacic acid, although neither of these substances had 
 been detected in them. But sebacic acid is no more 
 poisonous than benzoic acid, with which it has so many 
 properties ia common ; and the symptoms produced 
 are sufficient to show, that hydrocyanic acid is not the 
 poison. 
 
PUTRID POISONS. 351 
 
 The death which is the consequence of poisoning by 
 putrefied sausages succeeds very hngering and remarka- 
 ble symptoms. There is a gradual wasting of muscular 
 fibre, and of all the constituents of the body similarly 
 composed ; the patient becomes much emaciated, dries 
 to a complete mummy and finally dies. The carcase is 
 stiff, as if frozen, and is not subject to putrefaction. 
 During the progress of the disease the saliva becomes 
 viscous and acquires an offensive smell. 
 
 Experiments have been made for the purpose of as- 
 certaining the presence of some matter in the sausages 
 to which their poisonous action could be ascribed ; 
 but no such matter has been detected. Boiling water 
 and alcohol completely destroy the poisonous properties 
 of the sausages, without themselves acquiring similar 
 properties. 
 
 Now this is the peculiar character of all substances 
 which exert an action by virtue of their existing condi- 
 tion, — of those bodies the elements of which are in the 
 state of decomposition or transposition ; a state which is 
 destroyed by boiling water and alcohol without the cause 
 of the influence being imparted to those liquids ; for a 
 state of action or power cannot be preserved in a liquid. 
 
 Sausages, in the state here described, exercise an ac- 
 tion upon the organism, in consequence of the stomach 
 and other parts with which they come in contact not hav- 
 ing the power to arrest their decomposition ; and entering 
 the blood in some way or other, while still possessing 
 their whole power, they impart their peculiar action to 
 the constituents of that fluid. 
 
 The poisonous properties of decayed sausages are not 
 destroyed by the stomach as those of the smallpox virus 
 are. All the substances in the body capable of putre- 
 
352 POISONS, CONTAGIONS, MIASMS. 
 
 faction, are gradually decomposed during the course of 
 the disease, and after death nothing remains except fat, 
 tendons, bones, and a few other substances, which are in- 
 capable of putrefying in the conditions afforded by the 
 body. 
 
 Jt is impossible to mistake the modus operandi of this 
 poison, for Colin has clearly proved, that muscle, urine, 
 cheese, cerebral substance, and other matters, in a state 
 of putrefaction, communicate their own state of decom- 
 position to substances much less prone to change of com- 
 position than the blood. When placed in contact with 
 a solution of sugar, they cause its putrefaction, or the 
 transposition of its elements into carbonic acid and al- 
 cohol. 
 
 When putrefying muscle or pus Is placed upon a fresh 
 wound, it occasions disease and death. It is obvious, that 
 these substances communicate their own state of putre- 
 faction to the sound blood from which they were pro- 
 duced, exactly in the same manner as gluten in a state 
 of decay or putrefaction causes a similar transformation 
 in a solution of sugar- 
 Poisons of this kind are even generated by the body 
 itself in particular diseases. In smallpox, plague, and 
 syphilis, substances of a peculiar nature are formed from 
 the constituents of the blood. These matters are capa- 
 ble of inducing in the blood of a healthy individual a 
 decomposition similar to that of which they themselves 
 are the subjects ; in other words, they produce the same 
 disease. The morbid virus appears to reproduce itself 
 just as seeds appear to reproduce seeds. 
 
 The mode of action of a morbid virus exhibits such a 
 strong similarity to the action of yeast upon liquids con- 
 taining sugar and gluten, that the two processes have 
 
MORBID POISONS. 353 
 
 been long since compared to one another, although mere- 
 ly for the purpose of illustration. But when the phe- 
 nomena attending the action of each respectively are con- 
 sidered more closely, it will in reality be seen that their 
 influence depends upon the same cause. 
 
 In dry air, and in the absence of moisture, all these 
 poisons remain for a long time unchanged ; but when 
 exposed to the air in the moist condition, they lose very 
 rapidly their peculiar properties. In the former case^, 
 those conditions are afforded which arrest their decom- 
 position without destroying it ; in the latter, all the cir- 
 cumstances necessary for the completion of their decom- 
 position are presented. 
 
 The temperature at which water hoils^ and contact 
 tvith alcohol, render such poisons inert. Acids., salts of 
 mercury, sulphurous acid, chlorine, iodine, bromine, 
 aromatic substances, volatile oils, and particularly empy- 
 reumatic oils, smoke, and a decoction of coffee, com- 
 pletely destroy their contagious properties, in some cases 
 combining with them or otherwise effecting their decom- 
 position. Now all these agents, without exception, retard 
 fermentation, putrefaction, and decay, and when present 
 in sufficient quantity, completely arrest these processes 
 of decomposition. 
 
 A peculiar matter to which the poisonous action is 
 due, cannot, we have seen, be extracted from decayed 
 sausages; and it is equally impossible to obtain such a 
 principle from the virus of smallpox or plague, and for 
 this reason, that their peculiar power is due to an active 
 condition recognisable by our senses, only through the 
 phenomena which it produces. 
 
 In order to explain the effects of contagious matters, 
 a peculiar principle of life has been ascribed to them, — 
 30* 
 
354 POISONS, CONTAGIONS, MIASMS. 
 
 a life similar to that possessed by the germ of a seed, 
 wiiich enables it under favorable conditions to develope 
 and multiply itself. It would be impossible to find a 
 more correct figurative representation of these phenom- 
 ena; it is one which is applicable to contagions, as well 
 as to ferment, to animal and vegetable substances, in a 
 state of fermentation, putrefaction, or decay, and even to 
 a piece of decaying wood, which, by mere contact with 
 fresh wood, causes the latter to undergo gradually the 
 same change, and become decayed and mouldered. 
 
 If the property possessed by a body of producing such 
 a change in any other substance as causes the reproduc- 
 tion of itself, with all its properties, be regarded as life, 
 then, indeed, all the above phenomena may be ascribed 
 to life. But in that case they must not be considered 
 as the only processes due to vitality, for the above inter- 
 pretation of the expression embraces the majority of the 
 phenomena which occur in organic chemistry. Life 
 would, according to that view, be admitted to exist in 
 every body in which chemical forces act. 
 
 If a body A, for example, oxamide (a substance scarce- 
 ly soluble in water, and without the slightest taste), be 
 brought into contact with another compound B, which is 
 to be reproduced ; and if this second body be oxalic acid 
 dissolved in water, then the following changes are ob- 
 served to take place: — The oxamide is decomposed 
 by the oxalic acid, provided the conditions necessary for 
 their exercising an action upon one another are present. 
 The elements of water unite with the constituents of oxa- 
 mide, and ammonia is one product formed, and oxalic 
 acid the other, both in exactly the proper proportions to 
 combine and form a neutral salt. 
 
 Here the contact of oxamide and oxalic acid induces 
 
MORBID POISONS. 355 
 
 a transformation of the oxamide, which is decomposed 
 into oxalic acid and ammonia. The oxalic acid thus 
 formed as well as that originally added, are shared by 
 the ammonia, — or in other words, as much free oxalic 
 acid exists after the decomposition as before it, and is 
 of course still possessed of its original power. It mat- 
 ters not whether the free oxalic acid is that originally 
 added, or that newly produced ; it is certain that it has 
 been reproduced in an equal quantity by the decompo- 
 sition. 
 
 If we now add to the same mixture a fresh portion of 
 oxamide, exactly equal in quantity to that first used, and 
 treat it in the same manner, the same decomposition is 
 repeated ; the free oxalic acid enters into combination, 
 whilst another portion is liberated. In this manner a 
 very minute quantity of oxalic acid may be made to 
 effect the decomposition of several hundred pounds of 
 oxamide ; and one grain of the acid to reproduce itself 
 in unlimited quantity. 
 
 We know that the contact of the virus of smallpox 
 causes such a change in the blood, as gives rise to the 
 reproduction of the poison from the constituents of the 
 fluid. This transformation is not arrested until all the 
 particles of the blood which are susceptible of the de- 
 composition have undergone the metamorphosis. We 
 have just seen that the contact of oxalic acid with oxa- 
 mide caused the production of fresh oxalic acid, which 
 in its turn exercised the same action on a new portion 
 of oxamide. The transformation was only arrested in 
 consequence of the quantity of oxamide present being 
 limited. In their form both these transformations be- 
 long to the same class. But no one but a person quite 
 unaccustomed to view such changes will ascribe them 
 
356 POISONS, CONTAGIO]\S, MIASMS. 
 
 to a vital power, although we admit they correspond re- 
 markably to our common conceptions of life ; they are 
 really chemical processes dependent upon the common 
 chemical forces. 
 
 Our notion of life involves something more than mere 
 reproduction, namely, the idea of an active power exer- 
 cised by virtue of a definite form, and production and 
 generation i7i a definite form. By chemical agency we 
 can produce the constituents of muscular fibre, skin, and 
 hair ; but we can form by their means no organized tis- 
 sue, no organic cell. 
 
 The production of organs, the cooperation of a sys- 
 tem of organs, and their power not only to produce 
 their component parts from the food presented to them, 
 but to generate themselves in their original form and with 
 all their properties, are characters belonging exclusively 
 to organic life ; and constitute a form of reproduction 
 independent of chemical powers. 
 
 The chemical forces are subject to the invisible cause 
 by which this form is produced. Of the existence of 
 this cause itself we are made aware only by the phenom- 
 ena which it produces. Its laws must be investigated 
 just as we investigate those of the other powers which 
 effect motion and changes in matter. 
 
 The chemical forces are subordinate to this cause of 
 life, just as they are to electricity, heat, mechanical mo- 
 tion and friction. By the influence of the latter forces, 
 they suffer changes in their direction, an increase or 
 dimunition of their intensity, or a complete cessation or 
 reversal of their action. 
 
 Such an influence and no other is exercised by the 
 vital principle over the chemical forces ; but in every 
 
THEIR MODE OF ACTION. 357 
 
 case where combination or decomposition takes place, 
 chemical affinity and cohesion are in action. 
 
 The vital principle is only known to us through the 
 peculiar form of its instruments, that is, through the or- 
 gans in which it resides. Hence, whatever kind of en- 
 ergy a substance may possess, if it is amorphous and 
 destitute of organs from which the impulse, motion, or 
 change proceeds, it does not live. Its energy depends 
 in this case on a chemical action. -Light, heat, electrici- 
 ty, or other influences may increase, diminish, or ar- 
 rest this action, but they are not its efficient cause. 
 
 In the same way the vital principle governs the chem- 
 ical powers in the living body. All those substances to 
 which we apply the general name of food, and all the 
 bodies formed from them in the organism, are chemical 
 compounds. The vital principle has, therefore, no 
 Olhfer resistance to overcome, '" order to convert these 
 substances into component parts of the organism, than 
 the chemical powers by which their constituents are 
 held together. If the food possessed life, not merely 
 the chemical forces, but this vitality, would offev resist- 
 ance to the vital force of the organism it nourished. 
 
 All substances adapted for assimilation are bodies of 
 a very complex constitution, their atoms are highly com- 
 plex, and are held together only by a weak chemical 
 action. They are formed by the union of two or more 
 simpler compounds ; and in proportion as the number 
 of their atoms augments, their disposition to enter into 
 new combination is diminished ; that is, they lose the 
 power of acting chemically upon other bodies. 
 
 Their complex nature, however, renders them more 
 liable to be changed, by the agency of external causes, 
 and thus to suffer decomposition. Any external agen- 
 
358 POISONS, CONTAGIONS, MIASMS. 
 
 cy, in many cases even mechanical friction, is sufficient 
 to cause a disturbance in the equilibrium of the attrac- 
 tion of their constituents ; they arrange themselves 
 either into new, more simple, and permanent combina- 
 tions, or, if a foreign attraction exercise its influence 
 upon them, they arrange themselves in accordance with 
 that attraction. 
 
 The special characters of food, that is of substances 
 fitted for assimilation, are absence of active chemical 
 properties, and the capability of yielding to transforma- 
 tions. 
 
 The equilibrium in the chemical attractions of the 
 constituents of the food is disturbed by the vital princi- 
 ple, as we know it may be by many other causes. But 
 the union of its elements, so as to produce new combi- 
 nations and forms, indicates the presence of a peculiar 
 mode of attraction, and the existence of a power dis- 
 tinct from all other powers of nature, namely, the vitjil 
 principle. 
 
 All bodies of simple composition possess a greater 
 or less disposition to form combinations. Thus oxaHc 
 acid is one of the simplest of the organic acids, while 
 stearic acid is one of the most complex ; and the former 
 is the strongest, the latter one of the weakest in respect 
 to active chemical character. By virtue of this dispo- 
 sition, simple compounds produce changes in every 
 body which offers no resistance to their action ; they 
 enter into combination and cause decomposition. 
 
 The vital principle opposes to the continual action 
 of the atmosphere, moisture and temperature upon the 
 organism, a resistance which is, in a certain degree, 
 invincible. It is by the constant neutralization and re- 
 
THEIR MODE OF ACTION. 359 
 
 newal of these external influences that life and motion 
 are maintained. 
 
 The greatest wonder in the living organism is the 
 fact, that an unfathomable wisdom has made the cause 
 of a continual decomposition or destruction, namely, 
 the support of the process of respiration, to be the 
 means of renewing the organism, and of resisting all the 
 other atmospheric influences, such as those of moisture 
 and changes of temperature. 
 
 When a chemical compound of simple constitution 
 is introduced into the stomach, or any other part of the 
 organism, it must exercise a chemical action upon all 
 substances with which it comes in contact ; for we 
 know the pecuhar character of such a body to be an 
 aptitude and power to enter into combinations and 
 effect decompositions. 
 
 The chemical action of such a compound is of course 
 opposed by the vital principle. The results produced 
 depend upon the strength of their respective actions ; 
 either an equilibrium of both powers is attained, a 
 change being effected without the destruction of the 
 vital principle, in which case a medicinal effect is occa- 
 sioned ; or the acting body yields to the superior force 
 of vitality, that is, it is digested; or lastly, the chemical 
 action obtains the ascendency and acts as a poison. 
 
 Every substance may be considered as nutriment^ 
 which loses its former properties when acted on by the 
 vital principle, and does not exercise a chemical action 
 upon the living organ. 
 
 Another class of bodies change the direction, the 
 strength, and intensity of the resisting force (the vital 
 principle), and thus exert a modifying influence upon 
 the functions of its organs. They produce a disturbance 
 
360 POISONS, CONTAGIONS, MIASMS. 
 
 in the system, either by their presence, or by them- 
 selves undergoing a change ; these are medicaments. 
 
 A third class of compounds are called poisons, when 
 they possess the property of uniting with organs or with 
 their component parts, and when their power of effect- 
 ing this is stronger than the resistance offered by the 
 vital principle. 
 
 The quantity of a substance and its condition must, 
 obviously, completely change the mode of its chemical 
 action. 
 
 Increase of quantity is known to be equivalent to 
 superior affinity. Hence a medicine administered in 
 excessive quantity may act as a poison, and a poison in 
 small doses as a medicine. 
 
 Food will act as a poison, that is, it will produce 
 disease, when it is able to exercise a chemical action 
 by virtue of its quantity ; or, when either its condition 
 or its presence retards, prevents, or arrests the motion 
 of any organ. 
 
 A compound acts as a poison when all the parts of 
 an organ with which it is brought into contact enter into 
 chemical combination with it, while it may operate as a 
 medicine, when it produces only a partial change. 
 
 jNo other component part of the organism can be 
 compared to the blood, in respect of the feeble resist- 
 ance which it offers to exterior influences. The blood 
 is not an organ which is formed, but an organ in the act 
 of formation ; indeed, it is the sum of all the organs 
 which are being formed. The chemical force and the 
 vital principle hold each other in such perfect equilib- 
 rium, that every disturbance, however trifling, or from 
 whatever cause it may proceed, effects a change in the 
 blood. This liquid possesses so little of permanence, 
 
THEIR MODE OF ACTION. 361 
 
 that it cannot be removed from the body without imme- 
 diately suffering a change, and cannot come in contact 
 with any organ in the body, without yielding to its 
 attraction. 
 
 The slightest action of a chemical agent upon the 
 blood exercises an injurious influence ; even the mo- 
 mentary contact with the air in the lungs, although 
 effected through the medium of cells and membranes, 
 alters the color and other qualities of the blood. Ev- 
 ery chemical action propagates itself through the mass of 
 the blood ; for example, the active chemical condition 
 of the constituents of a body undergoing decomposition, 
 fermentation, putrefaction, or decay, disturbs the equilib- 
 rium between the chemical force and the vital prin- 
 ciple in the circulating fluid. The former obtains the 
 preponderance. Numerous modifications in the com- 
 position and condition of the compounds produced from 
 the elements of the blood, result from the conflict of the 
 vital force with the chemical affinity, in their incessant 
 endeavour to overcome one another. 
 
 All the characters of the phenomena of contagion 
 tend to disprove the existence of life in the contagious 
 matters. They without doubt exercise an influence 
 very similar to some processes in the living organism ; 
 but the cause of this influence is chemical action, which 
 is capable of being subdued by other chemical actions, 
 by opposed agencies. 
 
 Several of the poisons generated in the body by dis- 
 ease lose all their power when introduced into the stom- 
 ach, but others are not thus destroyed. 
 
 It is a fact very decisive of their chemical nature and 
 mode of action, that those poisons which are neutral or 
 alkaline, such as the poisonous matter of the contagious 
 31 
 
362 POISONS, CONTAGIONS, MIASMS. 
 
 fever in cattle, {typhus coniagiosus ruminantium^) or 
 that of the smallpox, lose their whole power of conta- 
 gion in the stomach ; whilst that of sausages, which has 
 an acid reaction, retains all its frightful properties under 
 the same circumstances. 
 
 In the former of these cases, the free acid present 
 in the stomach destroys the action of the poison, the 
 chemical properties of which are opposed to it ; whilst 
 in the latter it strengthens, or at all events does not offer 
 any impediment to poisonous action. 
 
 Microscopical examination has detected peculiar 
 bodies resembling the globules of the blood in malig- 
 nant putrefying pus, in the matter of vaccine, &c. 
 The presence of these bodies has given weight to the 
 opinion, that contagion proceeds from the development 
 of a diseased organic life ; and these formations have 
 been regarded as the living seeds of disease. 
 
 This view, which is not capable of discussion, has led 
 those philosophers who are accustomed to search for 
 explanations of phenomena in forms, to consider the 
 yeast produced by the fermentation of beer as possessed 
 of life. They have imagined it to be composed of ani- 
 mals or plants, which nourish themselves from the sugar 
 in which they are placed, and at the same time yield al- 
 cohol and carbonic acid as excrementitious matters. * 
 
 It would perhaps appear wonderful if bodies, possess- 
 ing a crystalline structure and geometrical figure, were 
 formed during the processes of fermentation and putre- 
 faction from the organic substances and tissues of or- 
 gans. We know, on the contrary, that the complete 
 dissolution into inorganic compounds is preceded by a 
 
 *JnnaJen der Pharmacie, Band xxix. S. 93 und 100. 
 
THEIR MODE OF ACTION. 363 
 
 series of transformations, in which the organic struc- 
 tures gradually resign their forms. 
 
 Blood, in a state of decomposition, may appear to 
 the eye unchanged ; and, when we recognise the globules 
 of blood in a liquid contagious matter, the utmost that 
 we can thence infer is, that those globules have taken no 
 part in the process of decomposition. All the phos- 
 phate of lime may be removed from bones, leaving them 
 transparent and flexible like leather, without the form of 
 the bones being in the smallest degree lost. Again, 
 bones may be burned until they be quite white, and con- 
 sist merely of a skeleton of phosphate of lime, but they 
 will still possess their original form. In the same way 
 processes of decomposition in the blood may affect in- 
 dividual constituents only of that fluid, which will be- 
 come destroyed and disappear, whilst its other parts will 
 maintain the original form. 
 
 Several kinds of contagion are propagated through 
 the air : so that, according to the view already men- 
 tioned, we must ascribe life to a gas, that is, to an aeri- 
 form body. 
 
 All the supposed proofs of the vitality of contagions 
 are merely ideas and figurative representations, fitted to 
 render the phenomena more easy of apprehension by 
 our senses, without explaining them. These figurative 
 expressions, with which we are so willingly and easily 
 satisfied in all sciences, are the foes of all inquiries into 
 the mysteries of nature ; they are like [he fata morgana, 
 which show us deceitful views of seas, fertile fields, and 
 luscious fruits, but leave us languishing when we have 
 most need of what they promise. 
 
 It is certain that the action of contagions is the result 
 of a peculiar influence dependent on chemical forces, 
 
364 POISONS, CONTAGIONS, MIASMS. 
 
 and in no way connected with the vital principle. This 
 influence is destroyed by chemical actions, and mani- 
 fests itself wherever it is not subdued by some antago- 
 nist power. Its existence is recognised in a connected 
 series of changes and transformations, in which it causes 
 all substances capable of undergoing similar changes to 
 participate. 
 
 An animal substance in the act of decomposition, or 
 a substance generated from the component parts of a 
 living body by disease, communicates its own condition 
 to all parts of the system capable of entering into the 
 same state, if no cause exist in these parts by which the 
 change is counteracted or destroyed. 
 
 Disease is excited by contagion. 
 
 The transformations produced by the disease assume 
 a series of forms. 
 
 In order to obtain a clear conception of these trans- 
 formations, we may consider the changes which substan- 
 ces, more simply composed than the living body, suffer 
 from the influence of similar causes. When putrefying 
 blood or yeast in the act of transformation is placed in 
 contact with a solution of sugar, the elements of the 
 latter substance are transposed, so as to form alcohol 
 and carbonic acid. 
 
 A piece of the rennet-stomach of a calf in a state of 
 decomposition occasions the elements of sugar to as- 
 sume a different arrangement. The sugar is converted 
 into lactic acid without the addition or loss of any ele- 
 ment. (1 atom of sugar of grapes C12 Hl2 012 
 yields two atoms of lactic acid =2 (C6 H6 06.) 
 
 When the juice of onions, or of beet-root, is made to 
 ferment at high temperatures, lactic acid, mannite, and 
 gum are formed. Thus, according to the different states 
 
THEIR MODE OF ACTION. 365 
 
 of the transposition of the elements of the exciting body, 
 the elements of the sugar arrange themselves in differ- 
 ent manners, that is, different products are formed. 
 
 The immediate contact of the decomposing substance 
 with the sugar, is the cause by which its particles are 
 made to assume new forms and natures. The removal 
 of that substance occasions the cessation of the decom- 
 position of the sugar, so that should its transformation 
 be completed before the sugar, the latter can suffer no 
 further change. 
 
 In none of these processes of decomposition is the 
 exciting body reproduced ; for the conditions necessary 
 to its reproduction do not exist in the elements of the 
 sugar. 
 
 Just as yeast, putrefying flesh, and the stomach of a 
 calf, in a state of decomposition, when introduced into 
 solutions of sugar, effect the transformation of this sub- 
 stance, without being themselves regenerated ; in the 
 same manner, miasms and certain contagious matters 
 produce diseases in the human organism, by communi- 
 cating the state of decomposition, of which they them- 
 selves are the subject, to certain parts of the organism, 
 without themselves being reproduced in their peculiar 
 form and nature during the progress of the decomposi- 
 tion. 
 
 The disease in this case is not contagious. 
 
 Now, when yeast is introduced into a mixed liquid 
 containing both sugar and gluten, such as wort, the act 
 of decomposition of the sugar effects a change in the 
 form and nature of the gluten, which is, in consequence, 
 also subjected to transformation. As long as some of 
 the fermenting sugar remains, gluten continues to be 
 separated as yeast, and this new matter in its turn ex- 
 31 * 
 
366 POISONS, CONTAGIONS, MIASMS. 
 
 cites fermentation in a fresh solution of sugar or wort. 
 If tiie sugar, however, should be first decomposed, the 
 gluten which remains in solution is not converted into 
 yeast. We see, therefore, that the reproduction of the 
 exciting body here depends, — 
 
 1. Upon the presence of that substance from which 
 it was originally formed. 
 
 2. Upon the presence of a compound which is capa- 
 ble of being decomposed by contact with the exciting 
 body. 
 
 If we express in the same terms the reproduction of 
 contagious matter in contagious diseases, since it is quite 
 certain that they must have their origin in the blood, we 
 must admit that the blood of a healthy individual contains 
 substances, by the decomposition of which the exciting 
 body or contagion can be produced. It must further 
 be admitted, when contagion results, that the blood con- 
 tains a second constituent, capable of being decomposed 
 by the exciting body. It is only in consequence of the 
 conversion of the second constituent, that the original 
 exciting body can be reproduced. 
 
 A susceptibility of contagion indicates the presence 
 of a certain quantity of this second body in the blood of 
 a healthy individual. The susceptibility for the disease 
 and its intensity must augnient according to the quantity 
 of that body present in the blood ; and in proportion to 
 its diminution or disappearance, the course of the dis- 
 ease will change. 
 
 When a quantity, however small, of contagious mat- 
 ter, that is of the exciting body, is introduced into the 
 blood of a healthy individual, it will be again generated 
 in the blood, just as yeast is reproduced from wort. Its 
 condition of transformation will be communicated to a 
 
THEIR MODE OF ACTION. 367 
 
 constituent of the blood ; and in consequence of the 
 transformation suffered by this substance, a body identi- 
 cal with or similar to the exciting or contagious matter 
 will be produced from another constituent substance of 
 the blood. The quantity of the exciting body newly 
 produced must constantly augment, if its further trans- 
 formation or decomposition proceeds more slowly than 
 that of the compound in the blood, the decomposition of 
 which it effects. 
 
 If the transformation of the yeast generated in the 
 fermentation of wort proceeded with the same rapidity 
 as that of the particles of the sugar contained in it, both 
 would simultaneously disappear when the fermentation 
 was completed. But yeast requires a much longer time 
 for decomposition than sugar, so that after the latter has 
 completely disappeared, there remains a much larger 
 quantity of yeast than existed in the fluid at the com- 
 mencement of the fermentation, — yeast which is still 
 in a state of incessant progressive transformation, and 
 therefore possessed of its peculiar property. 
 
 The state of change or decomposition which affects 
 one particle of blood, is imparted to a second, a third, 
 and at last to all the particles of blood in the whole 
 body. It is communicated in like manner to the blood 
 of another individual, to that of a third person, and so 
 on, — or in other words, the disease is excited in them 
 also. 
 
 It is quite certain that a number of peculiar substances 
 exist in the blood of some men and animals, which are 
 absent from the blood of others. 
 
 The blood of the same individual contains, in child- 
 hood and youth, variable quantities of substances, which 
 are absent from it in other stages of growth. The sus- 
 
368 POISONS, CONTAGIONS, MIASMS. 
 
 ceptibility of contagion by peculiar exciting bodies in 
 childhood, indicates a propagation and regeneration of 
 the exciting bodies, in consequence of the transformation 
 of certain substances which are present in the blood, and 
 in the absence of which no contagion could ensue. The 
 form of a disease is termed benignant^ when the trans- 
 formations are perfected on constituents of the body 
 which are not essential to life, without the other parts 
 taking a share in the decomposition ; it is termed malig- 
 nant when they affect essential organs. 
 
 It cannot be supposed that the different changes in the 
 blood, by which its constituents are converted into fat, 
 muscular fibre, substance of the brain and nerves, bones, 
 hair, »&.c., and the transformation of food into blood, can 
 take place without the simultaneous formation of new 
 compounds, which require to be removed from the body 
 by the organs of excretion. 
 
 In an adult these excretions do not vary much either 
 in their nature or quantity. The food taken is not em- 
 ployed in increasing the size of the body, but merely for 
 the purpose of replacing any substances which may be 
 consumed by the various actions in the organism ; every 
 motion, every manifestation of organic properties, and 
 every organic action being attended by a change in the 
 material of the body, and by the assumption of a new 
 form by its constituents.* 
 
 But in a child this normal condition of sustenance is 
 
 * The experiments of Barruel upon the different odors emitted from 
 blood on the addition of sulphuric acid, prove that peculiar substances 
 are contained in the blood of different individuals; the blood of a man 
 of a fair complexion and that of a man of dark complexion were found 
 to yield different odors; the blood of animals also differed in this re- 
 spect very perceptibly from that of man. — L. 
 
THEIR MODE OF ACTION. 369 
 
 accompanied by an abnormal condition of growth and in- 
 crease in the size of the body, and of each individual 
 part of it. Hence there must be a much larger quantity 
 of foreign substances, not belonging to the organism, dif- 
 fused through every part of the blood in the body of a 
 young individual. 
 
 When the organs of secretion are in proper action, 
 these substances will be removed from the system ; but 
 when the functions of those organs are impeded, they 
 will remain in the blood or become accumulated in par- 
 ticular parts of the body. The skin, lungs, and other 
 organs, assume the functions of the diseased secreting 
 organs, and the accumulated substances are eliminated 
 by them. If, when thus exhaled, they happen to be in 
 the state of progressive transformation, these substances 
 are contagious, that is, they are able to produce the 
 same state of disease in another healthy organism, pro- 
 vided the latter organism is susceptible of their action, — 
 or in other words, contains a matter capable of suffering 
 the same process of decomposition.* 
 
 The production of matters of this kind, which render 
 the body susceptible of contagion, may be occasioned 
 by the manner of living, or by the nutriment taken by an 
 individual. A superabundance of strong and otherwise 
 wholesome food may produce them, as well as a de- 
 ficiency of nutriment, uncleanliness, or even the use of 
 decayed substances as food. 
 
 All these conditions for contagion must be considered 
 as accidental. Their formation and accumulation in the 
 
 * Cold meat is always in a state of decomposition, that is, in a state 
 of eremacausis ; it is possible that this state may be communicated to 
 the system of a feeble individual, and may be one of the sources of 
 consumption. — L, 
 
370 POISONS, CONTAGIONS, MIASMS. 
 
 body may be prevented, and they may even be removed 
 from it without disturbing its most important functions or 
 health. Their presence is not necessary to life. 
 
 The action, as well as the generation of the matter of 
 contagion is, according to this view a chemical process 
 participated in by all substances in the living body, and 
 by all the constituents of those organs in which the vital 
 principle does not overcome the chemical action. The 
 contagion, accordingly, either spreads itself over every 
 part of the body, or is confined particularly to certain 
 organs, that is, the disease attacks all the organs or only 
 a few of them, according to the feebleness or intensity 
 of their resistance. 
 
 ]n the abstract chemical sense, reproduction of a con- 
 tagion depends upon the presence of two substances, 
 one of which becomes completely decomposed, but 
 Communicates its own state of transformation to the 
 second. The second substance thus thrown into a state 
 of decomposition is the newly formed contagion. 
 
 The second substance must have been originally a 
 constituent of the blood ; the first may be a body acci- 
 dentally present ; but it may also be a matter necessary 
 to life. If both be constituents indispensable for the 
 support of the vital functions of certain principal organs, 
 death is the consequence of their transformation. But 
 if the absence of the one substance which was a con- 
 stituent of the blood do not cause an immediate cessation 
 of the functions of the most important organs, if they 
 continue in their action, although in an abnormal condi- 
 tion, convalescence ensues. In this case, the products 
 of the transformations still existing in the blood are used 
 for assimilation, and at this period secretions of a pecu- 
 liar nature are produced. 
 
THEIR MODE OF ACTION. 371 
 
 When the constiluent removed from the blood is a 
 product of an unnatural manner of living, or when its 
 formation takes place only at a certain age, the suscepti- 
 bility of contagion ceases upon its disappearance. 
 
 The effects of vaccine matter indicate that an acciden- 
 tal constituent of the blood is destroyed by a peculiar 
 process of decomposition, which does not affect the 
 other constituents of the circulating fluid. 
 
 If the manner in which the precipitated yeast of Bava- 
 rian beer acts (page 317) be called to mind, the modus 
 operandi of vaccine lymph can scarcely be matter of 
 doubt. 
 
 Both the kind of yeast here referred to and the ordi- 
 nary ferment are formed from gluten, just as the vaccine 
 virus and the matter of smallpox are produced from the 
 blood. Ordinary yeast and the virus of human small- 
 pox, however, effect a violent tumultuous transformation, 
 the former in vegetable juices, the latter in blood, in 
 both of which fluids respectively their constituents are 
 contained, and they are reproduced from these fluids with 
 all their characteristic properties. The precipitated yeast 
 of Bavarian beer on the other hand acts entirely upon the 
 sugar of the fermenting liquid and occasions a very pro- 
 tracted decomposition of it, in which the gluten which is 
 also present takes no part. But the air exercises an in- 
 fluence upon the latter substance, and causes it to assume 
 a new form and nature, in consequence of which this 
 kind of yeast also is reproduced. 
 
 The action of the virus of cowpox is analogous to 
 that of the low yeast ; it communicates its own state of 
 decomposition to a matter in the blood, and from a second 
 matter is itself regenerated, but by a totally different 
 mode of decomposition ; the product possesses the mild 
 form, and all the properties of the lymph of cowpox. 
 
372 POISONS, CONTAGIONS, MIASMS. 
 
 The susceptibility of infection by the virus of human 
 smallpox must cease after vaccination, for the substance 
 to the presence of which this susceptibility is owing has 
 been removed from the body by a peculiar process of 
 decomposition artificially excited. But this substance 
 may be again generated in the same individual so that he 
 may again become liable to contagion, and a second or a 
 third vaccination will again remove the peculiar substance 
 from the system. 
 
 Chemical actions are propagated in no organs so easily 
 as in the lungs, and it is well known that diseases of the 
 lungs are above all others frequent and dangerous. 
 
 If it is assumed that chemical action and the vital prin- 
 ciple mutually balance each other in the blood, it must 
 further be supposed that the chemical powers vvill have a 
 certain degree of preponderance in the lungs, where the 
 air and blood are in immediate contact ; for these organs 
 are fitted by nature to favor chemical action ; they offer 
 no resistance to the changes experienced by the venous 
 blood. 
 
 The contact of air with venous blood is limited to a 
 very short period of lime by the motion of the heart, 
 and any change beyond a determinate point is, in a cer- 
 tain degree, prevented by the rapid removal of the blood 
 which has become arterialized. Any disturbance in the 
 functions of the heart, and any chemical action from 
 without, even though weak, occasions a change in the 
 process of respiration. Solid substances also, such as 
 dust from vegetable, (meal,) animal, (wool,) and inor- 
 ganic bodies, act in the same way as they do in a satu- 
 rated solution of a salt in the act of crystallization, that 
 is, they occasion a deposition of solid matters from the 
 blood, by which the action of the air upon the latter is 
 altered or prevented. 
 
THEIR MODE OF ACTION. 373 
 
 When gaseous and decomposing substances, or those 
 which exercise a chemical action, such as sulphuretted 
 hydrogen and carbonic acid, obtain access to the lungs, 
 they meet with less resistance in this organ than in any 
 other. The chemical process of slow combustion in 
 the lungs is accelerated by all substances in a state of de- 
 cay or putrefaction, by ammonia and alkalies ; but it is 
 retarded by empyreumatic substances, volatile oils, and 
 acids. Sulphuretted hydrogen produces immediate de- 
 composition of the blood, and sulphurous acid combines 
 with the substance of the tissues, the cells, and mem- 
 branes. 
 
 When the process of respiration is modified by con- 
 tact with a matter in the progress of decay, when this 
 matter communicates the state of decomposition, of 
 which it is the subject, to the blood, disease is produced. 
 
 If the matter undergoing decomposition is the product 
 of a disease, it is called contagion ; but if it is a product 
 of the decay or putrefaction of animal and vegetable sub- 
 stances, or if it acts by its chemical properties, (not by 
 the state in which it is,) and therefore enters into combi- 
 nation with parts of the body, or causes their decompo- 
 sition, it is termed mia^m. 
 
 Gaseous contagious matter is a miasm emitted from 
 blood, and capable of generating itself again in blood. 
 
 But miasm properly so called, causes disease without 
 being itself reproduced. 
 
 All the observations hitherto made upon gaseous con- 
 tagious matters prove, that they also are substances in a 
 state of decomposition. When vessels filled with ice 
 are placed in air impregnated with gaseous contagious 
 matter, their outer surfaces become covered with water 
 containing a certain quantity of this matter in solution. 
 32 
 
374 POISONS, CONTAGIONS, MIASMS. 
 
 This water soon becomes turbid, and in common language 
 putrefies, or, to describe the change more correctly, the 
 state of decomposition of the dissolved contagious matter 
 is completed in the water. 
 
 All gases emitted from putrefying animal and vegetable 
 substances in processes of disease, generally possess a pe- 
 culiar nauseous offensive smell, a circumstance which, in 
 most cases, proves the presence of a body in a stale of 
 decomposition. Smell itself may in many cases be con- 
 sidered as a reaction of the nerves of smell, or as a re- 
 sistance offered by the vital powers to chemical action. 
 
 Many metals emit a peculiar odor when rubbed, but 
 this is the case with none of the precious metals, — those 
 which suffer no change when exposed to air and moisture. 
 Arsenic, phosphorus, musk, the oils of linseed, lemons, 
 turpentine, rue, and peppermint, possess an odor only 
 when they are in the act of eremacausis (oxidation at 
 common temperatures). 
 
 The odor of gaseous contagious matters is owing to 
 the same cause ; but it is also generally accompanied by 
 ammonia, which may be considered in many cases as the 
 means through which the contagious matter receives a 
 gaseous form, just as it is the means of causing the smell 
 of innumerable substances of little volatility, and of many 
 which have no odor. (Robiquet.)* 
 
 Ammonia is very generally produced in cases of dis- 
 ease ; it is always emitted in those in which contagion is 
 generated, and is an invariable product of the decom- 
 position of animal matter. The presence of ammonia in 
 the air of chambers in which diseased patients lie, par- 
 ticularly of those afflicted with a contagious disease, may 
 
 * Jinn, de Chivi. et de Phijs., t. xv. p. 27. 
 
THEIR MODE OF ACTION. 375 
 
 be readily detected ; for the moisture condensed by ice 
 in the manner just described, produces a white precipi- 
 tate in a solution of corrosive sublimate, just as a solution 
 of ammonia does. The ammoniacal salts also, which 
 are obtained by the evaporation of rain water after an 
 acid has been added, when treated with lime so as to set 
 free their ammonia, emit an odor most closely resembling 
 that of corpses, or the peculiar smell of dunghills. 
 
 By evaporating acids in air containing gaseous conta- 
 gions, the ammonia is neutralized, and we thus prevent 
 further decomposition, and destroy the power of the con- 
 tagion, that is, its state of chemical change. Muriatic 
 and acetic acids, and in several cases nitric acid, are to 
 be preferred for this purpose before all others. Chlorine 
 also is a substance which destroys ammonia and organic 
 bodies with much facility ; but it exerts such an injurious 
 and prejudicial influence upon the lungs, that it may be 
 classed amongst the most poisonous bodies known, and 
 should never be employed in places in which men 
 breathe. 
 
 Carbonic acid and sulphuretted hydrogen, which are 
 frequently evolved from the earth in cellars, mines, wells, 
 sewers, and other places, are amongst the most pernicious 
 miasms. The former may be removed from the air by 
 alkalies ; the latter, by burning sulphur (sulphurous acid), 
 or by the evaporation of nitric acid. 
 
 The characters of many organic compounds are well 
 worthy of the attention and study both of physiologists 
 and pathologists, more especially in relation to the mode 
 of action of medicines and poisons. 
 
 Several of such compounds are known, which to all 
 appearance are quite indifferent substances, and yet can- 
 not be brought into contact with one another in water 
 
376 POISONS, CONTAGIONS, MIASMS. 
 
 without suffering a complete transformation. All sub- 
 stances which thus suffer a mutual decomposition, possess 
 complex atoms ; ihey belong to the highest order of 
 chemical compounds. For example, amygdalin, a con- 
 stituent of bitter almonds, is a perfectly neutral body, of a 
 slightly bitter taste, and very easily soluble in water. 
 But when it is introduced into a watery solution of synap- 
 tas, (a constituent of sweet almonds,) it disappears com- 
 pletely without the disengagement of any gas, and the 
 water is found to contain free hydrocyanic acid, hydruret 
 of benzule (oil of bitter almonds), a peculiar acid, and 
 sugar, all substances of which merely the elements ex- 
 isted in the amygdalin. The same decomposition is ef- 
 fected when bitter almonds, which contain the same white 
 matter as the sweet, are rubbed into a powder and 
 moistened with water. Hence it happens that bitter 
 almonds pounded and digested in alcohol, yield no oil of 
 bitter almonds containing hydrocyanic acid, by distilla- 
 tion with water ; for the substance which occasions the 
 formation of those volatile substances, is dissolved by 
 alcohol without change, and is therefore extracted from 
 the pounded almonds. Pounded bitter almonds contain 
 no amygdalin, also, after having been moistened with 
 water, for that substance is completely decomposed 
 when they are thus treated. 
 
 No volatile compounds can be detected by their smell 
 in the seeds of the Sinapis alba and ^S. nigra. A fixed 
 oil of a mild taste is obtained from them by pressure, 
 but no trace of a volatile substance. If, however, the 
 seeds are rubbed to a fine powder, and subjected to dis- 
 tillation with water, a volatile oil of a very pungent taste 
 and smell passes over along with the steam. But if, on 
 the contrary, the seeds are treated with alcohol previ- 
 
THEIR MODE OF ACTION. 377 
 
 ously to their distillation with water, the residue does 
 not yield a volatile oil. The alcohol contains a crys- 
 talline body called sinapin, and several other bodies. 
 These do not possess the characteristic pungency of the 
 oil, but it is by the contact of then:i with water, and with 
 the albuminous constituents of the seeds, that the vola- 
 tile oil is formed. 
 
 Thus bodies regarded as absolutely indifferent in in- 
 organic chemistry, on account of their possessing no 
 prominent chemical characters, when placed in con- 
 tact with one another, mutually decompose each other. 
 Their constituents arrange themselves in a peculiar man- 
 ner, so as to form new combinations ; a complex atom 
 dividing into two or more atoms of less complex consti- 
 tution, in consequence of a mere disturbance in the at- 
 traction of their elements. 
 
 The white constituents of the almonds and mustard 
 which resemble coagulated albumen, must be in a pecu- 
 liar state in order to exert their action upon amygdalin, 
 and upon those constituents of mustard from which the 
 volatile pungent oil is produced. If almonds, after be- 
 ing blanched and pounded, are thrown into boiling water, 
 or treated with hot alcohol, with mineral acids, or with 
 salts of mercury, their power to effect a decomposition 
 in amygdalin is completely destroyed. Synaptas is an 
 azotized body which cannot be preserved when dissolv- 
 ed in water. Its solution becomes rapidly turbid, de- 
 posiies a white precipitate, and acquires the offensive 
 smell of putrefying bodies. 
 
 It is exceedingly probable that the peculiar state of 
 
 transposition into which the elements of synaptas are 
 
 thrown, when dissolved in water, may be the cause of 
 
 the decomposition of amygdalin, and formation of the 
 
 32* 
 
3/8 POISONS, CONTAGIONS, MIASMS. 
 
 new products arising from it. The action of synaptas 
 in this respect is very similar to that of rennet upon 
 sugar. 
 
 Malt, and the germinating seeds of corn in general, 
 contain a substance called diastase, which is formed 
 from the gluten contained in them, and cannot be 
 brought in contact with starch and water, without effect- 
 ing a change in the starch. 
 
 When bruised malt is strewed upon warm starch 
 made into a paste with water, the paste, after a few min- 
 utes becomes quite liquid, and the water is found to 
 contain, in place of starch, a substance in many respects 
 similar to gum. But when more malt is added and the 
 heat longer continued, the liquid acquires a sweet taste, 
 and all the starch is found to be converted into sugar of 
 grapes. 
 
 The elements of diastase have at the same time ar- 
 ranged themselves into new combinations. 
 
 The conversion of the starch contained in food into 
 sugar of grapes in diabetes indicates that amongst the 
 constituents of some one organ of the body a substance 
 or substances exist in a state of chemical action, to 
 which the vital principle of the diseased organ opposes 
 no resistance. The component parts of the organ must 
 suffer changes simultaneously with the starch, so that 
 the more starch is furnished to it, the more energetic 
 and intense the disease must become ; while if only 
 food which is incapable of suffering such transformations 
 from the same cause is supplied, and the vital energy is 
 strengthened by stimulant remedies and strong nourish- 
 ment, the chemical action may finally be subdued, or 
 in other words, the disease cured. 
 
THEIR MODE OF ACTION. 379 
 
 The conversion of starch into sugar may also be ef- 
 fected by pure gluten, and by dilute mineral acids. 
 
 From all the preceding facts, we see that very va- 
 rious transpositions, and changes of composition and 
 properties, may be produced in complex organic mole- 
 cules, by every cause which occasions a disturbance in 
 the attraction of their elements. 
 
 When moist copper is exposed to air containing car- 
 bonic acid, the contact of this acid increases the affinity 
 of the metal for the oxygen of the air in so great a 
 degree that they combine, and the surface of the cop- 
 per becomes covered with green carbonate of copper. 
 Two bodies, which possess the power of combining 
 together, assume, however, opposite electric conditions 
 at the moment at which they come in contact. 
 
 When copper is placed in contact with iron, a pecu- 
 liar electric condition is excited, in consequence of 
 which the property of the copper to unite with oxygen 
 is destroyed, and the metal remains quite bright. 
 
 When formate of ammonia is exposed to a tempera- 
 ture of 388^ F. (180° C.) the intensity and direction 
 of the chemical force undergo a change, and the condi- 
 tions under which the elements of this compound are 
 enabled to remain in the same form cease to be present. 
 The elements, therefore, arrange themselves in a new 
 form ; hydrocyanic acid and water being the results of 
 the change. 
 
 Mechanical motion, friction, or agitation, is sufficient 
 to cause a new disposition of the constituents of fulmin- 
 ating silver and mercury, that is, to effect another ar- 
 rangement of their elements, in consequence of which, 
 new compounds are formed. 
 
 We know that electricity and heat possess a decided 
 
380 POISONS, CONTAGIONS, MIASMS. 
 
 influence upon the exercise of chemical affinity ; and 
 that the attractions of substances for one another are 
 subordinate to numerous causes which change the con- 
 dition of these substances, by altering the direction of 
 their attractions. In the same manner, therefore, the 
 exercise of chemical powers in the living organism is 
 dependent upon the vital principle. 
 
 The power of elements to unite together, and to form 
 peculiar compounds, which are generated in animals and 
 vegetables, is chemical affinity ; but the cause by which 
 they are prevented from arranging themselves according 
 to the degrees of their natural attractions, — the cause, 
 therefore, by which they are made to assume their 
 peculiar order and form in the body, is the vital prin- 
 ciple. 
 
 After the removal of the cause which forced their 
 union, — that is, after the extinction of life, — most 
 organic atoms retain their condition, form, and nature, 
 only by a vis inertice ; for a great law of nature proves 
 that matter does not possess the power of spontaneous 
 action. A body in motion loses its motion only when 
 a resistance is opposed to it ; and a body at rest cannot 
 be put in motion or into any action whatever, without 
 the operation of some exterior cause. 
 
 The same numerous causes which are opposed to 
 the formation of complex organic molecules, under 
 ordinary circumstances, occasion their decomposition 
 and transformations when the only antagonist power, 
 the vital principle, no longer counteracts the influence 
 of those causes. Contact with air and the most feeble 
 chemical action now effect changes in the complex 
 molecules ; even the presence of any body the particles 
 of which are undergoing motion or transposition is often 
 
THEIR MODE OF ACTION. 381 
 
 sufficient to destroy their state of rest, and to disturb 
 the statical equihbrium in the attractions of their con- 
 stituent elements. An immediate consequence of this 
 is, that they arrange themselves according to the differ- 
 ent degrees of their mutual attractions, and that new 
 compounds are formed in which chemical affinity has 
 the ascendancy, and opposes any further change, while 
 the conditions under which these compounds were 
 formed remain unaltered. 
 
APPENDIX. 
 
 GROWTH OF P1.ANTS WITHOUT MOULD. 
 
 (See page 118.) 
 
 " Some account of a suspended plant of Ficus Australis, 
 which was grown for eight months without earth in the stove 
 of the Botanic Garden at Edinburgh. By Mr. William Mac- 
 nab, superintendent of the Garden." (From the 3d volume of 
 the Edinburgh Philosophical Journal, p. 77. Slightly abridged.) 
 
 " Ficus Jiustralis is a native of New South Wales, and was 
 introduced into the British gardens in 1789, by the Right Hon- 
 orable Sir Joseph Banks. The plant is not uncommon now in 
 collections in this country, where it has been usually treated 
 as a greenhouse plant; and in a good greenhouse it thrives 
 tolerably well, although it seems rather more impatient of cold 
 than many of the plants from the same country. 
 
 " When I came to superintend this garden in 1810, I found 
 a specimen of it among the greenhouse plants, where it re- 
 mained for some time afterwards ; but owing to the bad con- 
 struction of the greenhouse here, and the very hardy way in 
 which I was obliged to treat the plants in that department, I 
 I did not find ihejicus thrive so well as I had been accustomed 
 to see it do. I concluded that it required more heat, and in the 
 spring of 1811 I placed it in the stove, when it soon began to 
 grow as vigorously as I had ever seen it do. 
 
 " The stem of the plant was about a foot in height before any 
 branches set out ; on one of the branches, above two feet from 
 the junction with the stem, a root was put out. As soon as this 
 had grown about a foot long, I placed a pot under it. As 
 soon as I found this pot filled with roots, I determined to try 
 
384 
 
 APPENDIX. 
 
 whether if supplied plentifully with water it would support 
 the whole plant. 
 
 "In August, 1816, I left off watering the original large pot, 
 and supplied the smaller one very freely with water ; I kept it in 
 this state for about eight months, till the earth in the large pot 
 was so completely dry, that I was satisfied the plant could 
 receive no nourishment from it. The shruh continued quite as 
 healthy and vigorous as when supplied with water at the origi- 
 nal root. In the spring of 1817, I took off the large pot in 
 which the original roots were, and exposed the roots to the full 
 rays of the sun, by gradually shaking off the dry earth from 
 among them ; this had no ill effect on the plant, as it still re- 
 mained perfectly healthy; it, however, had the effect of making 
 roots be put out freely all over the plant, much more so than 
 had hitherto been the case. 
 
 "In the latter end of the summer of 1817, I placed a root in 
 a third pot, which was put out from a branch about three feet 
 from the junction with the stem, and on the opposite side of the 
 plant from that which had supported it for some time past. As 
 soon as I found this pot filled with fibres, I supplied it freely 
 with water, and kept the other small pot dry, as I had done 
 before with the original root. I found the plant still continue 
 equally vigorous as before. In the spring of 1818, I took away 
 the second pot, which I had for some time kept dry, and ex- 
 posed the roots gradually, as I had formerly done with those in 
 the original pot. 
 
 " The third pot, which now alone supported the plant, was 
 four feet from the lower end of the stem, and very near to the 
 extremity of the branch, the original roots, and the second set 
 of roots, both hanging loose in the air. The plant, however, 
 remained in this state for nearly a year in perfect health. In 
 May, 1819, 1 took a very small pot, about two inches in diam- 
 eter, and filled it with earth as I had done the others, and set 
 it on the surface of the earth in the third pot which now sup- 
 ported the plant. Into this small pot I introduced a root which 
 came from the same branch, a little below the one which was 
 in the larger (third) pot. As soon as the small pot was filled 
 with roots, I supplied it freely with water, and gave the larger 
 pot none but what might happen to run through tiie small one. 
 
APPENDIX. 385 
 
 After remaining in this state for near two months, I cut the 
 branch off between the two pots ; I still supplied the small pot 
 only with water, but occasionally at this time threw a little 
 water over the whole plant. It continued to look as well as it 
 had done before. 
 
 "In July last, 1819, I examined the small pot (the fourth 
 used), and found it completely filled with roots, very little earth 
 remaining in the pot. By this time the plant appeared to me 
 to be very tenacious of life, and I determined to try whether it 
 would live wholly tvithout earth. I accordingly took the small 
 (fourth) pot off, and gradually worked off what little earth 
 remained among the roots. I at this time, however, threw 
 plenty of water over the leaves, generally twice in the day: 
 this was done about the latter end of July, when the weather 
 was very warm, but it seemed to have no bad effects on the 
 Ficus. 
 
 " What may appear rather remarkable, is, that though this 
 Ficus is a plant by no means free in producing fruit in the 
 usual way of cultivating it, this specimen, quite suspended with- 
 out a particle of earth, was loaded with figs during the months 
 of September, October, and part of November. Two fruit were 
 produced at the axilla of almost every leaf, and these were 
 quite as large as I had ever seen on the plant in the hothouses 
 of Kew garden. The plant is beginning to grow or extend, 
 although it has now been suspended for eight months without 
 a particle of earth, and during that time we have had very hot 
 weather, and also very cold weather. Roots have been put out 
 very freely all over the stem and branches during that time. 
 The plant now (February, 1819,) measures 7^ feet between 
 the extremity of the root and the top of the branches, and the 
 stem at the thickest part is 5^ inches in circumference." 
 
 33 
 
386 APPENDIX. 
 
 EXPERIMENTS AND OBSERVATIONS ON THE ACTION OF CHAR- 
 COAL FROM WOOD ON VEGETATION. BY EDWARD LUCAS. 
 
 (See page 118.) 
 
 " In a division of a low hothouse in the botanical garden at 
 Munich, a bed was set apart for young tropical plants, but in- 
 stead of being filled with tan, as is usually the case, it was filled 
 with the powder of charcoal, (a material which could be easily 
 procured,) the large pieces of charcoal having been previously 
 separated by means of a sieve. The heat was conducted by 
 means of a tube of white iron into a hollow space in this bed' 
 and distributed a gentle warmth, sufficient to have caused tan 
 to enter into a state of fermentation. The plants placed in this 
 bed of cliarcoal quickly vegetated, and acquired a healthy ap- 
 pearance. Now, as always is the case in such beds, the roots 
 of many of the plants penetrated through the holes in the bot- 
 tom of the pots, and then spread themselves out ; but these plants 
 evidently surpassed in vigor and general luxuriance, plants 
 grown in the common way, for example, in tan. Several of 
 them, of which I shall only specify the beautiful Thunhergia 
 alata, and the genus Peireskia, throve quite astonishingly ; the 
 blossoms of the former were so rich, that all who saw it affirmed 
 Ihey had never before seen such a specimen. It produced, also, 
 a number of seeds without any artificial aid, while in most 
 cases it is necessary to apply the pollen by the hand. The 
 PeireskicE grew so vigorously, that the P. aculeata produced 
 shoots several ells in length, and the P. grandifolia acquired 
 leaves of a foot in length. These facts, as well as the quick 
 germination of the seeds which had been scattered spontane- 
 ously, and the abundant appearance of young Filines, naturally 
 attracted my attention, and I was gradually led to a series of 
 experiments, the results of which may not be uninteresting ; 
 for, besides being of practical use in tlie cultivation of most 
 plants, they demonstrate also several facts of importance to 
 physiology. " The first experiment which naturally suggested 
 itself, was to mix a certain proportion of charcoal with the earth 
 in which different plants grew, and to increase its quantity 
 according as the advantage of the method was perceived. An 
 
APPENDIX, 387 
 
 addition of | of charcoal, for example, to vegetable mould, ap- 
 peared to answer excellently for the Gesneria, and Gloxynia, 
 and also for the tropical Aroidece. with tuberous roots. The two 
 first soon excited the attention of connoisseurs, by the great 
 beauty of all their parts and their general appearance. They 
 surpassed very quickly those cultivated in the common way, 
 both in the thickness of their stems and dark color of their 
 leaves ; their blossoms were beautiful, and their vegetation last- 
 ed much longer than usual, so much so, that in the middle of last 
 November, when other plants of the same kinds were dead, these 
 were quite fresh and partly in bloom. Aroidece, took root very 
 rapidly, and their leaves surpassed much in size the leaves of 
 those not so treated : the species, which are reared as orna- 
 mental plants on account of the beautiful coloring of their 
 leaves, (I mean, such as the Caladium bicolor, Pidum, Pacilt, 
 &c.,) were particularly remarked for the liveliness of their tints; 
 and it happened here, also, that the period of their vegetation 
 was unusually long. A cactus planted in a mixture of equal 
 parts of charcoal and earth throve progressively, and attained 
 double its former size in the space of a few weeks. The use of 
 the charcoal was very advantageous with several of the Brome- 
 liacea, and Liliacece, with the Citrus and Begonia also, and even 
 with the PalmoR. The same advantage was found in the case 
 of almost all those plants for which sand is used, in order to 
 keep the earth porous, when charcoal was mixed with the soil 
 instead of sand; the vegetation was always rendered stronger 
 and more vigorous. 
 
 " At the same time that these experiments were performed 
 with mixtures of charcoal with different soils, the charcoal was 
 also used free from any addition, and in this case the best re- 
 sults were obtained. Cuts of plants from different genera 
 took root in it well and quickly ; I mention here only the Eu- 
 phorbia fastuosa and falgens which took root in ten days, Pa7^~ 
 danus utilis in three months, P. amaryllif alius, ChamoEdorea 
 elatior in four weeks, Piper nigrum, Begonia, Ficus, Cecropia, 
 Chiococca, Buddlcja, Hakea, Phyllanthus, Capparis, Laurus, 
 Slifflia, Jacquinia, Mimosa, Cactus, in from eight to ten days, 
 and several others amounting to forty species, including Ilex, 
 and many others. Leaves, and pieces of leaves, and even pe- 
 
388 APPENDIX. 
 
 (lunculi, or petioles, took root and in part budded in pure clinr- 
 coal. Amongst otiicrs we mny mention the fidiola of several of 
 tilt: Cijcadcn; as having taken root, as also did part of the leaves 
 of the licgonia Tclsairia', and Jacaranda brasiliensis ; leaves of 
 the Euphorbia Jasluosa, Oxalia Bitrrilieri, Ficus, Cyclamen, 
 Polyanihes, Meseinhrianlhtmum ; also, the delicate leaves of the 
 Lopho.tpcrmum and Martijnia, pieces of u leaf of the JJgnve 
 .^incricanit ; tufts of Piniis, &c. ; and all without the aid of a 
 previously formed bud.* 
 
 *' Pure charcoal acts excellently as a means of curing unheal- 
 thy plants. A Dorianlhes excelsa, for example, which had been 
 droojjinfj for tiiree years, was rendered coniplelcly healthy in a 
 very short time by this means. An orange tree which had the 
 very connnon disease in which the leaves become yellow, ac- 
 quired within four weeks its healthy green color, when the up- 
 per surface of the earth was removed from the pot in which it 
 was contained, and a ring of charcoal of an inch in thickness 
 strewed in its place around the periphery of the pot. The same 
 was the case wiih the Gardenia. 
 
 " I should be led too far were I to state all the results of the 
 experiments which I have made with charcoal. The object of 
 this paper is merely to show the general effect exercised by this 
 sub.stance on vegetation, but the reader who takes particular 
 interest in tiie subject, will find more extensive observations in 
 the "Jlllgemeine dculsche Gartenzeilung" of Otto and Dietrich, 
 in Berlin, f 
 
 "The charcoal employed in these experiments was the dust- 
 like powder of charcoal from firs and jiines, such as is used iii 
 the forges of blacksmiths, and may be easily procured in any 
 quantity. It was found to have most effect when allowed to lie 
 
 * The cuttings of several of these plants being full of moisture, re- 
 quire to be partially dried before they are placed in the soil, and are 
 witli diibciilly nmde to strike root in the usual method. The clmr- 
 coiil is probably useful from its absorbing aiui antiseptic power. The 
 Ilakea is extremely difRcuU to pro])niratc from cuUini>s. All the Lau- 
 rits tribe are obstinate, sonic of them have not rooted under three 
 years from the time of planting. — IV. 
 
 I See an account of these experiments in Loudon's Gardener's 
 Magazine, for March, ]b41 
 
APPENDIX. 389 
 
 during the winter exposed to the action of the air. In order to 
 ascertain the effects of different kinds of charcoal, experiments 
 were also made upon that obtained from the hard woods and 
 peat, and also upon animal chiircoal, although I foresaw the 
 probal)ilit.y that none of them would answer so well as that of 
 pine-wood, both on account of its porosity and the ease with 
 which it is decomposed. 
 
 "It is superfluous to remark, that in treating plants in the 
 manner here described, they must be plentifully supplied with 
 water, since the air having such free access penetrates and 
 dries the roots, so that unless this precaution is taken, the fail- 
 ure of all such experiments is unavoidable. 
 
 "The action of charcoal consists primarily in its preserving 
 tiie parts of the plants with which it is in contact; whether 
 they be roots, branches, leaves, or pieces of leaves, unchanged 
 in their vital power for a long space of time, so that the plant 
 obtains time to develop the organs which are necessary for its 
 further support and propagation. There can scarcely be a doubt 
 also that the charcoal undergoes decomposition ; for after being 
 used five or six years it liccomes a coaly earth ; and if this is 
 the case, it must yield carbon, or carbonic oxide, abundantly 
 to the plants growing in it, and thus afford the principal sub- 
 stance necessary for the nutrition of vegetables. In what other 
 manner indeed can we explain the deep green color and great 
 luxuriance of the leaves and every part of the plants, which 
 can be obtained in no other kind of soil, according to the opinion 
 of men well qualified to judge ? It exercises likewise a favor- 
 able influence by decomposing and absorbing the matters ab- 
 sor))ed [query, excreted] by the roots, so as to keep the soil 
 free from the putrefying sub.stances which are often the cause 
 of the death of the spongiolfB. Its porosity as well as the power 
 which it possesses, of absorbing water with rapidity, and, after 
 its saturation, of allowing all other water to sink through it, 
 are causes also of its favorable effects. These experiments 
 show what a close affinity the component parts of charcoal have 
 to all plants, for every experiment was crowned with success, 
 although plants belonging to a great many different families 
 were subjected to trial." — {Buchner^s Reptrlorium, ii. Reihe, 
 xix. Bd. S. 38.) 
 
 33* 
 
390 
 
 APPENDIX. 
 
 O.V THE ROTATION OF CROPS AT BINGEN ON THE RHINE. 
 
 (See page 217.) 
 
 The alternation of crops with esparsette and lucern is now 
 •JrliVersally adopted in Bingen and its vicinity as well as in the 
 Palatinate ; the fields in these districts receive manure only 
 once every nine years. In the first year after the land has 
 been manured, turnips are sown upon it, in the next following 
 years barley, with esparsette or lucern ; in the seventh year 
 potatoes, in the eighth wheat, in the ninth barley ; in the tenth 
 year it is manured, and then the same rotation again takes 
 place. 
 
 ON A MODE OF MANURING VINES. 
 
 The observations contained in the following pages should be 
 extensively known, because they furnish a remarkable proof of 
 the principles which have been stated in the preceding part of 
 the work, both as to the manner in which manure acts, and on 
 the origin of the carbon and nitrogen of plants. 
 
 They prove that a vineyard may be retained in fertility with- 
 out the application of animal matters, when the leaves and 
 branches pruned from the vines are cut into small pieces and 
 used as manure. According to the first of the following state- 
 ments, both of which merit complete confidence, the perfect 
 fruitfulness of a vineyard has been maintained in this manner 
 for eight years, and according to the second statement, for ten 
 years. 
 
 Now, during this long period, no carbon was conveyed to the 
 soil, for that contained in the pruned branches was the produce 
 of the plant itself, so that the vines were placed exactly in the 
 same condition as trees in a forest which received no manure. 
 Under ordinary circumstances a manure containing potash must 
 be used, otherwise the fertility of the soil will decrease. This 
 is done in all wine countries, so that alkalies to a very con- 
 siderable amount must be extracted from the soil. 
 
APPENDIX. 391 
 
 When, however, the method of manuring now to be described 
 is adopted, the quantity of alkalies exported in the wine does 
 not exceed that which the progressive disintegration of the soil 
 every year renders capable of being absorbed by the plants. 
 On the Rhine 1 litre of wine is calculated as ■ the yearly pro- 
 duce of a square metre of land (10.8 square feet English). Now 
 if we suppose that the wine is three fourths saturated with 
 cream of tartar, a proportion much above the truth, then we 
 remove from every square metre of land with the wine only 1.8 
 gramme of potash. 1000 grammes (1 litre) of champagne yield 
 only 1.54, and the same quantity of Waclienheimer 1.72 of a 
 residue which after being heated to redness is found to consist 
 of carbonates. 
 
 One vine-stock, on an average, grows on every square metre 
 of land, and 1000 parts of the pruned branches contain 56 to 
 60 parts of carbonate, or 38 to 40 parts of pure potash. Hence 
 it is evident that 45 grammes, or 1 ounce, of these branches 
 contain as much potash as 1000 grammes (1 litre) of wine. But 
 from ten to twenty times this quantity of branches are yearly 
 taken from the above extent of surface. 
 
 In the vicinity of Johannisberg, Rudesheim, and Budesheim, 
 new vines are not planted after the rooting out of the old 
 stocks, until the land has lain for five or six years in barley and 
 esparsette or lucern ; in the sixth year the young stocks are 
 planted, but not manured till the ninth. 
 
 ON THE MANURING OF THE SOIL IN VINEYARDS.* 
 
 " In reference to an article in your paper. No. 7, 1838, and 
 No. 29, 1839, I cannot omit the opportunity of again calling the 
 public attention to the fact that nothing more is necessary for 
 the manure of a vineyard, than the branches which are cut from 
 the vines themselves. 
 
 * Slightly abridged from an article by M. Krebs, of Seeheirn in the 
 *' Zeiischrift fur die landwirthschafdichen Vereine des Grosherzogihvms 
 Hessen." No. 28, July 9, 1840. 
 
392 APPENDIX. 
 
 " My vineyard has been manured in this way for eight years, 
 without receiving any other kind of manure, and yet more 
 beautiful and richly laden vines could scarcely be pointed out. 
 I formerly followed the method usually practised in this district, 
 and was obliged in consequence to purchase manure to a large 
 amount. This is now entirely saved, and my land is in excel- 
 lent condition. 
 
 " When I see the fatiguing labor used in the manuring of 
 vineyards, — horses and men toiling. up the mountains with 
 unnecessary materials, — I feel inclined to say to all, Come to 
 my vineyard and see how a bountiful Creator has provided that 
 vines shall manure themselves, like the trees in a forest, and 
 even better than they ! The foliage falls from trees in a forest, 
 only when they are withered, and they lie for years before they 
 decay ; but the branches are pruned from the vine in the end 
 of July or beginning of August whilst still fresh and moist. If 
 they are then cut into small pieces and mixed with the earth, 
 they undergo putrefaction so completely, that, as I have learned 
 by experience, at the end of four weeks not the smallest trace 
 of them can be found." 
 
 '■'■ Remarks of the editor. — We find the following notices of 
 the same fact in Henderson's ' History of Wines of the old and 
 new time': — 
 
 " ' The best manure for vines is the branches pruned from the 
 vines themselves, cut into small pieces, and immediately mixed 
 with the soil.' 
 
 " These branches were used as manure long since in the 
 Bergstrasse. M. Frauenfelder says ; * 
 
 " ' I remember that twenty years ago, a man called Peter 
 Miiller had a vineyard here which he manured with the branches 
 pruned from the vines, and continued this practice for thirty 
 years. His way of applying them was to hoe them into the 
 soil after having cut them into small pieces. 
 
 "'His vineyard was always in a thriving condition ; so much 
 so indeed, that the peasants here speak of it to this day wonder- 
 
 * Badisches landwirthschnftliches Wochenblatt, v. 1834. S. 52 und 79. 
 
APPENDIX. 393 
 
 ing that old Miiller had so good a vineyard, and yet used no 
 manure.' 
 
 "Lastly, Wilhelm Ruf, of Schriesheim, writes ; 
 
 " ' For the last ten years I have been unable to place dung 
 on my vineyard, because I am poor and can buy none. But 
 I was very unwilling to allow my vines to decay, as they are 
 my only source of support in my old age ; and I often walked 
 very anxiously amongst them, without knowing what I should 
 do. At last my necessities became greater, which made me- 
 more attentive, so that I remarked that the grass was longer on 
 some spots where the branches of the vine fell than on those on 
 which there were none. So I thought upon the matter, and 
 then said to myself: If these branches can make the grass 
 large, strong, and green, they must also be able to make my 
 plants grow better, and become strong and green. I dug there- 
 fore my vineyard as deep as if I would put dung into it, and 
 cut the branches into pieces, placing them in the holes and 
 covering them with earth. In a year I had the very great 
 satisfaction to see my barren vineyard become quite beautiful. 
 This plan I continued every year, and now my vines grow 
 splendidly, and remain the whole summer green, even in the 
 greatest heat. 
 
 " ' All my neighbours wonder very much how my vineyard is 
 so rich, and that I obtain so many grapes from it, and yet they 
 all know that I have put no dung upon it for ten years.' " 
 
 Illustration of Fermentation. 
 
 (See page 275.) 
 
 When yeast is made into a thin paste with water, and I cubic 
 centimetre of this mixture introduced into a graduated glass 
 receiver filled with mercury, in which are already 10 grammes 
 of a solution of cane-sugar, containing 1 gramme of pure solid 
 sugar ; it is found, after the mixture has been exposed for 24 
 hours to a temperature of from 20 to 25° C. (68 — 77°F.), that a 
 volume of carbonic acid has been formed, which, at 0° C. (32*' F.) 
 and an atmospheric pressure indicated by 0.76 metre Bar. would 
 be from 245 to 250 cubic centimetres. But to this quantity we 
 must add 11 cubic centimetres of carbonic acid, with which the 
 
394 APPENDIX. 
 
 11 grammes of liquid would be saturated, so that in all 255 — 
 259 cubic centimetres of carbonic acid are obtained. This 
 volume of carbonic acid corresponds to from 0.503 to 0.5127 
 gramme by weight. 
 
 DR. DANA'S VIEWS RESPECTING GEINE. 
 
 In the Report on a Reexamination of the Economical Geology 
 of Massachusetts, by Professor E. Hitchcock, 1838, Dr. S. L. 
 Dana lias described a method of analyzing soils, and presented 
 us with his views of the state in which vegetable and animal 
 matter exists in them, and the changes which it undergoes 
 before being taken up by plants. 
 
 Dr. Dana is of opinion that air and moisture convert insoluble 
 into soluble geine, and that there is no problem of greater 
 practical importance to be solved in agricultural chemistry than 
 the determination of the quantity of these substances in soils. 
 It lies, he remarks, at the foundation of all successful cultiva- 
 tion, and its importance has been undervalued. Earths and 
 geine are what is essential to fertility, and soils will be fertile 
 in proportion as geine is mixed witli the earths. 
 
 "Among the many economical modes of producing geine, the 
 ploughing in of vegetable matter has held a high rank. Nature 
 teaches us to turn in the dry plant. Dried leaves are her 
 favorite morsels, and the very fact, that Nature always takes 
 the dried plant, from which to prepare the food for growing 
 vegetables, should have taught us long ago, the wisdom of 
 ploughing in dry crops." The careful collecting and husband- 
 ing of dry leaves needs not to be urged upon the intelligent 
 agriculturist. 
 
 The proportion of geine in different soils as stated by Dr. 
 Dana have been given at page 59. 
 
 Application of Solution of Geine. 
 
 In the Appendix to the Third Report of the Agriculture of 
 Massachusetts, 1840, by Dr. Colman, is a statement of Mr. Nich- 
 ols, of Danvers, of the results of the practical application of Dr. 
 Dana's views, from which the following extracts are made. Dr. 
 
APPENDIX. 395 
 
 Dana's directions for preparing a solution of geine are as fol- 
 lows : Boil one hundred pounds of dry, pulverized peat with two 
 and a half pounds of white ash, (an article imported from Eng- 
 land,) containing 36 to 55 per cent, of pure soda, or its equiva- 
 lent in pearlash or potash, in a potash kettle, with 130 gallons 
 of water ; boil for a few hours, let it settle, and dip off the clear 
 liquor for use. Add the same quantity of alkali and water, boil 
 and dip off as before. The dark colored brown solution con- 
 tains about half an ounce per gallon of vegetable matter. It 
 is to be applied by watering grain crops, grass lands, or in any 
 other way the farmer's quick wit will point out. In the month 
 of June, I prepared a solution of geine, (says Mr. N.) obtained 
 not by boiling, but by steeping the mud as taken from the mead- 
 ow, in a weak lye in tubs. The proportion was about, — peat 
 100 lbs., potash 1 lb., water 50 gallons ; stirred occasionally for 
 about a week, when the dark brown solution, described by Dr. 
 Dana, was dipped off and applied to some rows of corn, a por- 
 tion of a piece of starved barley, and a bed of onions sown on 
 land not well prepared for that crop. The crop of barley on 
 the portion watered was more than double the quantity both 
 in straw and grain to that on other portions of the field, the 
 soil and treatment of which were otherwise precisely similar. 
 
 In June, four rows (of the onions) were first watered with 
 the solution of geine. In ten days, the onions in these rows 
 were nearly double the size of the others. All but six rows of 
 the remainder were then watered. The growth of these soon 
 outstripped the unwatered remainder. Eventually the whole 
 piece was watered with the solution, excepting the ends of some 
 of tlie rows, which produced only very small onions, and, had it 
 not been done, Mr. Nichols believes that not a single bushel of 
 a good size would have been produced. The onions when 
 measured, making ample allowance for the tops which had not 
 been stripped off, were adjudged equal to four bushels to the 
 square rod, or at the rate of 640 bushels to the acre. 
 
 On the JVaiure of Geine. 
 
 In consequence of the difference of opinion in regard to the 
 substance which has been called geine, and which has been 
 made public in the Agricultural Reports and Scientific Journals, 
 
396 APPENDIX. 
 
 it was deemed desirable, and due to the advocates of opposite 
 views, to proffer to them the opportunity of appending to this 
 volume such remarks as they might be desirous of presenting 
 in addition to, or in support of, what they have already given to 
 the public. From the replies to the letters addressed to the gen- 
 tlemen who have advocated the different views, the following 
 extracts are given, together with an extract from the forthcoming 
 Final Report on the Economical Geologi) of this State, for which 
 I am indebted to the politeness of its distinguished author. Pro- 
 fessor Hitchcock, of Amherst. It will be obvious that Liebig is 
 conceived to have taken but a limited view of the action of 
 geine. — W. 
 
 Extract from a letter to Professor Hitchcock, from S. L. Dana, 
 M. D., of Loivell, dated March 18th, 1841. 
 
 "It appears to me, that some of our friends seem to forget the 
 foundation on which we have laid, I may not say an edifice, but 
 the staging and scantling for them to build by. We have spoken 
 of geine 1st. Agriculturally; 2d. Chemically. 
 
 " Agriculturally, we define it to be ' all the decomposed organic 
 matter of the soil.' It is soluble or insoluble, including in this 
 its salts. These salts are soluble in, or decomposed by alkalies. 
 In these states it is the food of plants. Now this is an agricul- 
 tural and practical view. It was to these points to which all my 
 letters in your 2d Report tended. I avoided all discussion about 
 the how of its operation, and its chemical constitution. Mr. Col- 
 man addressed such queries to me, that I touched on these 
 points. I stated to him my belief that these were 'forms of 
 geine.' I have stated to you, that I believed crenic and apocrenic 
 acid bear such a relation to geine. When, still later. Dr. Jack- 
 son denied the existence of geine, and asserted it to be a com- 
 pound only of these acids, I admitted his discovery, and have at 
 tempted to show how this is compatible with the existence of 
 geine as a distinct principle. What, then, is geine.' — and now 
 we speak chemically. Did we and Berzelius mean the same 
 thing when speaking in this sense ? and does Berzelius now 
 deny, that what he called geine in 1833, no longer exists ? He 
 may have dropped the name geine, as applicable to the three sub- 
 
APPENDIX. 397 
 
 stances into which he then separated mould, — ' extract of mould,' 
 'geine,' and 'carbonaceous mould,' — but he still retains 'humic 
 acid.' What, then, was humic acid in his estimation, in 1833? 
 He considered ulmin and humin synonymous then, and both as 
 meaning geine. In his account of the attempts to fix the atomic 
 weight of geine, he quotes Boullay's analysis of ulmin. So I 
 understand geine, when called upon to speak of it chemically. 
 So far Berzelius goes. Geine, ulmin, humin. are identical. But 
 Dr. Jackson says, Berzelius has abandoned geine : its name, but 
 not as a principle. 
 
 "He still retains 'humic acid' as one of the ingredients of 
 soil. We have shown, that this was his geine, 1833. He still. 
 then, admits geine as a separate, independent principle. It is 
 the same which we call geine, when speaking chemically. Ber- 
 zelius has dropped the name only as applicable to his tbree/ornis 
 of geine ; we retain it, for all forms, speaking agriculturally. I 
 have shown in my letter to you, relating to Dr. Jackson's discov- 
 eries of the compound nature of geine, that Berzelius, in his 
 Traiti de Chemie, 1833, said that crenic and apocrenic acid ex- 
 isted in soils. If Dr. Jackson was ignorant of this, he probably 
 was not unacquainted with Shepard's remarks on your 2d report, 
 where Hermann's analysis of humus is cited, as composed of cre- 
 nic, apocrenic, and ulmic acids. I trust Dr. Jackson does not 
 claim to be the discoverer of the first named acids in soil. If he 
 is not, what new views has Berzelius appeared to support as pe- 
 culiarly Dr. Jackson's. Berzelius may have new views, but I do 
 not yet understand them enough to see wherein they conflict 
 with his former statements, or controvert the position we have 
 taken. To be sure, I only know them from the printed reports 
 of Dr. Jackson's remarks at the late Agricultural Meeting in 
 Boston. As regards Liebig, there are so many points to be set- 
 tled in vegetable physiology, that his views can be considered, 
 at present, only as highly ingenious, bold, and counter to expe- 
 rience. 
 
 " But still, as you request my views on one point of his argu- 
 ment, I give them as they occur, and am glad so to do, as it 
 allows me to say, that there is a point on which we are over- 
 looked ; I mean the action of growing plants upon silicates.* 
 
 " * See my letter to Mr. Colinan, in his 2d report." 
 
 34 
 
398 APPENDIX. 
 
 " Growing plants decompose silicates. Potash and other bases 
 are let loose upon geine. That becomes soluble. Now, whether 
 this is or is not taken up by plants, or only thus extended and 
 divided, so that the air easier acts on it, to evolve carbonic acid, 
 you will perceive, that so long as the plant is vigorous and grow- 
 ing, so much the more is geine rendered soluble. The plant ceas- 
 ing its functions, geine loses one great source of its solubility. 
 Now we have never contended, that simple geine or geates (here- 
 in Liebig admits the existence of such a principle, under the name 
 of humus,) are dissolved by rain only, or depend on that only 
 for being put in a soluble state. If that was the case, why then 
 Liebig's data being correct, his conclusion would follow. But 
 this is only a partial view of the action of oxygen of air upon 
 geine. It produces not only carbonic acid, but water also, by 
 uniting witli the hydrogen of the geine. The amount of water 
 proceeding from this cause is truly astonishing. It has been 
 found by actual experiment, (see JVicholso7i^s Journal, 1809 or 
 1608, I forget which,) equal, per hour, from an acre of fresh 
 ploughed sward, to 950 pounds ; while the undisturbed ground 
 gave not a drop. This is equal to the evaporation per hour from 
 an acre after most copious rains. And to show that this depends 
 upon the decomposition of the geine, the quantity of water evapo- 
 rated per hour, in a dry time, from a well-manured acre, was 
 found equal to 5000 pounds. (I quote from memory.) We have 
 here, then, an abundant source of water to solve, in the action 
 of air upon geine. If I remember Liebig, (I have seen the 
 book only a few hours,) he himself says that water is a pro- 
 duct of the decomposition of geine. I wonder this source of 
 fluid to dissolve his geine, escaped him. Indeed it would not, if 
 he had not pressed the infinitesimal small quantity which rain 
 could dissolve, into his argument against the necessity of geine. 
 
 " Liebig takes it for granted, that it is the rain only which is 
 to dissolve geine and geates. He says it is not enough. We 
 offer him an abundant source in the fountain of water from ge- 
 ine. He may say, it is not enough. We add, if indeed we should 
 not begin there, the action of growing plants upon silicates, 
 evolving bases whose action upon geine renders it easily soluble. 
 I think these causes of the solubility of geine enough, if no rain 
 fell, and no smnll argument to prove that geine exercises other 
 
APPEiVDIX. 399 
 
 functions in soil, besides evolving carbonic acid. Geine ceasing, 
 barrenness follows. When Raspail and Liebig prove the con- 
 trary, I '11 believe ourselves wrong in our views. 
 "With great regard, 
 
 " Ever your friend, 
 
 "SAMUEL L. DANA." 
 
 From Dr. Dana's Letter of June 22d, 1840, to Prof. Hitchcock.* 
 
 " From the days of Vauquelin, who first noticed ulmin, to the 
 present time, this substance has been investigated by the most 
 distinguished chemists, under the name of ulmin, or humus, or 
 geine. These are convertible terms, they mean one and the 
 same thing. 
 
 "Malagutti has obtained ulmic acid in distinct crystals. By 
 boiling these in weak acids, a black substance is deposited, which 
 he calls ulmin, identical in its composition with the acid. Once 
 and for all, I consider ulmin, humus, geine, ulmic, humic, and 
 geic acid, one identical substance ; whether neutral or acid its 
 constitution, ever one and the same, subject to the great law of 
 organic chemistry, that proximate compounds act as simple ele- 
 ments," 
 
 [For the analysis of geate of copper and geic acid, the chem- 
 ical reader is referred to the Report, p. 121. From these the 
 number 42 is adopted as the atomic number of geine.] 
 
 "A substance found by different observers so identical in com- 
 position, by actual analysis, whose theoretical confirms its ana- 
 lytical constitution, which forms definite compounds, and whose 
 history and properties are better understood than a large propor- 
 tion of the objects in organic chemistry, may well be considered 
 a definite chemical compound. That it is so, is believed by all 
 chemists, except Raspail, whose principles would equally reduce 
 the larger portion of organic substances, to carbon and water; 
 and Dr. C. T. Jackson, who reduces geine into a mixture of cre- 
 
 * This letter appears to have been written in consequence of a 
 statement by Dr. Jackson, that " the substance originally mistaken by 
 Berzelius, and subsequently by Dr. Dana," was only a mixture of 
 crenic and apocrenic acids. — W. 
 
400 APPENDIX. 
 
 nic and apocrenic acids. Others have admitted these acids in 
 combination with geine, in soils. Berzelius, their discoverer, 
 and to whom we are indebted for all that is known of their his- 
 tory, years ago said, that crenic and apocrenic acids existed in 
 soils in small quantity ; and moreover states, that these acids are 
 among the general products of putrefaction. 
 
 " The doctrine, then, that they are found in soils, is not the 
 doctrine of yesterday nor of to-day, — it is no new thing; but 
 the doctrine that geine is a mixture of these acids, that geine 
 has no independent existence, is new ; and coming from a source 
 commanding our respect, requires a careful consideration. The 
 various opinions which have been formed on the subject of geine, 
 owe their existence in part to the varied means which produce 
 this substance. It comes from organic matter by putrefaction, 
 by the action of acids and of alkalies, caustic or carbonated, by 
 the action of alkaline earths, by alumina, by metallic oxides, 
 acting on organic matter, especially when assisted by heat, and 
 as a general law, we may say that all substances, oxidating, and 
 gently acting on organic matter, produce geine. It is produced 
 by fire, by heating or roasting organic matter, and hence its 
 ?Lbundance in soot, in crude pyroligneous acid, in charcoal, and 
 baked wood. It is found in carburet of iron ; and cast iron, 
 treated with acids, leaves an insoluble residue, having the prop- 
 erties of geine. Of all the agents which thus change organic 
 matter into geine, the action of the alkalies and of the alkaline 
 earths is most powerful : next to them ranks alumina, which is 
 little if at all inferior to lime, when assisted by growing plants. 
 It is the decomposition of the aluminous silicate, by living plants, 
 which lets loose the alumina, to convert insoluble into soluble 
 geine. But to return, the mode of acting here is in many cases 
 purely ^ catalytic,'' the action of presence, — the same elements 
 re-arranged, a new order takes place, — while in other cases, a 
 part of the original compound is removed, new substances are 
 produced. In whatever way we may produce the proximate 
 principle geine, whose definite constitution we see has been so 
 well determined, it is not at all probable, that it proceeds, per 
 saUum, from organization to its atomic constitution. There 
 exist, doubtless, intermediate states, other compounds, which 
 chemistry has already, or will hereafter detect ; forms of geine, 
 
APPENDIX. 401 
 
 SO to speak. In this class, I include crenic and apocrenic acid. 
 Nor can we determine whether these arise from a catalytic 
 change in geine, or whether they are formed first, and then unite 
 to produce that definite compound. But the properties and 
 actions are so very distinct from those of geine, that the last 
 cannot be owing to a mere mixture of the two first. From the 
 small quantity in which they accompany geine in soils, it is 
 probable that they derive their origin from a change in the ele- 
 ments of that substance ; and if ever geine has been loholly re- 
 duced to crenic and apocrenic acid, I think it is no difficult mat- 
 ter to show how this result has been produced by the agent 
 employed, and by the manipulation. Cases analogous are familar 
 to all chemists, and the very ease witli which crenic passes into 
 apocrenic acid, may help our conceptions of the possibility of a 
 mere new arrangement of the elements of geine, — an arrange- 
 ment producing two well defined acids, being considered as the 
 separation of those which previously were only mechanically 
 mixed. As evidence of the evanescent nature of crenic acid, it 
 is well established, that its solution in water, by simple exposure 
 to air, becomes apocrenic acid : hence its name : its existence, 
 as Berzelius says, depends on crenic acid, just as apo-\heme de- 
 pends for its existence on a solution of organic extract in water- 
 Without crenic there can be no apocrenic acid. These acids 
 have been separated. Their insulation is one of the most diffi- 
 cult of chemical operations, requiring not one, but several solu- 
 tions and separations by sulphuretted hydrogen before we can 
 estimate their quantity, or be assured of their purity. Separated, 
 their characters are as follows : — Both resemble vegetable ex- 
 tract : 
 
 Crenic acid. ..Apocrenic acid. 
 
 Color yellow, Brown. 
 
 Transparent, 
 
 Amorphous, Amorphous, 
 
 Taste acid, then astringent, Astringent. 
 
 Excessively so\\xh\e in water and Slightly soluble in water. 
 
 " « in alcohol. Slowly soluble in pure alcohol. 
 
 Solution in water, precipitates 
 by sal-ammoniac in flocks. 
 
 34 
 
 * 
 
402 APPENDIX. 
 
 Crenates, Jlpocrenates. 
 
 Of alkalios, like yellow extracts, Of alkalies, black friable mass- 
 and very soluble in water, and es ; in water a dark soluble 
 weak alcohol. brown color. 
 
 Of lime, neutral, soluble in 
 
 water, subsalt, insoluble. 
 Of magnesia, easily soluble in Of alkaline earths, solve in 
 water. water, yellow color. The 
 
 subsalts quite insoluble. 
 Of alumina, neutral insoluble in Of alumina, neutral, insoluble : 
 
 water: supersalt, soluble. supersalt, soluble in water. 
 
 Of iron, soluble in water. Of iron, protoxide, soluble in 
 
 water: peroxide, insoluble in 
 water. 
 
 " From the statement I have already made of the elements 
 which enter into soluble geine,.it will be seen that a small part 
 only of soils exist, as a geic salt. The phosphoric acid I have 
 enumerated among those elements, confining the term ' soluble 
 geine ' in that case to all which an alkali dissolved. The phos- 
 phoric acid proceeds from a partial decomposition of phosphate 
 of lime, or subphosphate of alumina. It is not an element of 
 geine. The iron and alumina are dissolved as salts of geine. 
 We conclude that the greater part of the geine of soils exists 
 uncombined. If this substance, as it exists in soils, is only a 
 mixture of crenic and apocrenic acids, then, from the established 
 properties of these acids and their salts, this result must follow. 
 The soluble organic mutler of soils ought to be completely solved 
 by tvater and alcohol. No other agents are required to detect 
 not only the existence, but the total amount of these acids, to 
 determine in fact the amount of soluble geine. Simply boiling 
 the soil in v/ater should extract all the crenic acid. ' It is ex- 
 cessively soluble in water,' says Berzelius, — so soluble, that the 
 water of the Porla well, tiie source whence the acid was first 
 obtained, is colored brown by it. Pure alcohol, will then dis- 
 solve all the apocrenic acid ; and we may thus at once ascertain 
 the amount of these acids. Admitting the properties of crenic 
 and apocrenic acid, I do not see how we can escape this conclu- 
 sion. Nor will it alter the case, if it be said that the acids are 
 
APPENDIX. 403 
 
 combined with the bases of earths and oxides. We still are 
 driven to the same conclusion. Noav this is a resultj which I 
 presume the propounder of this doctrine of the mixed nature of 
 geine, will not admit. He knows how very trifling is the pro- 
 portion of organic matter, or its salts which yield to alcohol, or 
 to water. I do not mean to deny that this little is crenic or apo- 
 crenic acids or their salts. Nor will the advocates of the doc- 
 trine deny, that all the crenic acid will, by exposure to air, pass 
 into apocrenic acid. If, then, geine be a mixture of acids, and 
 is insoluble in the agents which act easily on these acids while 
 separate, we may reasonably conclude, that the elements of these 
 acids have arranged themselves anew, entered into a true, chemical 
 combination, to form geine, a definite proximate principle, whose 
 separate, independent existence, whose properties, combinations, 
 and uses, are as well established as any facts in chemistry. 
 
 " Finding, then, that the action of water and alcohol on the 
 geine of soils is Avholly different from that which ought to ensue, 
 if it is a mixture of crenic and apocrenic acids, other agents 
 have been employed to effe'Ct their separation. Now these 
 agents are precisely those which we have enumerated above, as 
 having the power to alter the arrangement of the elements of 
 organic matter, or of geine ; developing either acid properties, 
 without altering its constitution, or rearranging its elements, 
 without addition or subtraction. The long and repeated digestion 
 in carbonate of ammonia, has produced, not educed, crenic and 
 apocrenic acids. — We are not informed of any other result, of 
 any other product: no evolution of gas, indicating that any de- 
 composition has occurred. From the acknowledged chemical 
 tact of Dr. C. T. Jackson, we infer, that geine has afforded him 
 only crenic and apocrenic acids. That these are the products 
 of his process can then be easily understood. 
 
 "The atomic weight of geine we have shown is 42. This 
 number differs but little from the sum of the weight of two 
 atoms of crenic acid, and one atom of apocrenic acid. Berzelius 
 determined the atomic weight of crenic acid to be, 13.50 
 
 of apocrenic acid, 16.50 
 then 2 atoms crenic = 13.50 X 2 = 27. 
 
 1 atom apocrenic 16.50 
 
 43.50 
 
404 APPENDIX. 
 
 Which differs only 0.89 from Boullay's number for geine, deduced 
 from his analysis of ulmate of copper. But allowing the crenic 
 acid to be 12.75, we have then 2 atoms = 25.50 
 1 atom apocrenic = 16.50 
 
 42.00 
 And that 12.75 is probably the true number, will appear from re- 
 arranging the atoms of geine, so as to constitute two atoms of 
 crenic and one of apocrenic acid. — I have met with no analysis 
 of the atomic constitution of these acids,* but taking their atom- 
 ic weights as above, and the result of Dr. C. T. Jackson, that 
 geine is wholly separated into these acids, then the number of 
 the atoms constituting their weight is as follows: — 
 Crenic acid. Apocrenic acid. 
 
 Carbon, 11. = 8.25 10 == 7.50 
 
 Hydrogen, 4.= .50 8 = 1. 
 
 Oxygen, 4. = 4. 8 = 8. 
 
 12.75X2+ 16.50 = 42 
 
 The number of atoms in 42 geine is 64. as above : 
 
 and we have one atom geine = C.^^ H." O.^^ 
 
 Which resolved into 
 
 2 atoms crenic acid, = C.'" H.^ O.* 
 1 atom apocrenic acid, = C}° H.® O.* 
 
 From one atom of geine, = C' H.'^ O.^* 
 
 * " Hermann has given the following as the constitution of the cre- 
 nic, apocrenic, and uhnic acids. .American Journal of Science, ^c, 
 Vol. 36, p. 3G9. 
 
 Crenic. J}pocrenic. 
 
 Carbon, 535.0 (=7 atoms.) 1070.1 (= 14 atoms.) 
 
 Hydrogen, 99.8 (=16 " ) 87.2 (=14 " ) 
 
 Nitrogen, 88.5 (=1 " ) 265.5 (= 3 " ) 
 
 Oxygen, 600.0 (=6 " ) 300.0 (= 3 " ) 
 
 1323.3 (combining weight) 1722.9 (combining weight) 10000 
 " It is hardly necessary to observe, tiiat tiiese results confirm the 
 suffcestion of Dr. Dana in the text, that crenic and apocrenic acids 
 were not probably so constituted, as to be entirely conveited into ge- 
 ine without an excess of any of the ingredients. — E. H." 
 
APPENDIX. 405 
 
 " It may be said, that it may be proved that my statement of the 
 atomic constitution of these acids is not confirmed by analysis. 
 So much the better. That will prove that geine cannot be a 
 mixture of them. Though these elements theoretically admit of 
 this arrangement, it is not at all probable, that nature forms cre- 
 nie and apocrenic acids, out of which to form geine, by their 
 complete chemical union ; still less is it probable, that she mere- 
 ly mixes these acids. The constitution of geine is too firmly 
 settled, to allow us to believe, tiiat it is a haphazard mixture. 
 The evidence of the existence of a simple proximate principle, 
 geine, is rather strengthened than weakened by the above view 
 of its probable theoretical changes. And as Dr. Jackson states 
 that he has actually separated geine into two acids, he has fur- 
 nished new and unquestioned proof of the existence of that prin- 
 ciple. If the sum of the weights of his crenic and apocrenic 
 acids equals the weight of the organic part of his soluble geine, 
 he furnishes the highest evidence we can have, of the separate, 
 independent existence of that element. I believe he has seen all 
 that he states, and I must ask him to believe that the conclusions 
 to which we have arrived respecting the nature, constitution, and 
 properties of geine are equally founded on experiment. While 
 I thus freely admit the result he states, I express my conviction, 
 that what he has seen he has produced, that he has merely re- 
 arranged the elements of a well-known, definite compound, by 
 the long-continued action of ammonia. Such changes may not 
 be readily comprehended by the majority, into whose hands your 
 report may fall, — all, however, now-a-days understand that there 
 is such a thing as carbon, such elements as oxygen and hydro- 
 gen, which last by their union produce water. Now it is evident 
 by a glance at the above arrangement of the elements of geine 
 and crenic and apocrenic acids, that these are each and all re- 
 -solvable into carbon and water. We may as well deny the ex- 
 istence of crenic and apocrenic acids because resolvable into 
 carbon and water, as to deny the existence of geine because re- 
 solvable into crenic and apocrenic acids. A glance, too, at the 
 above arrangement, will show us how crenic becomes apocrenic 
 acid by simple exposure ; for by absorbing oxygen, each atom 
 parts with 6 atoms carbon, and then 2 atoms crenic form one 
 of apocrenic acid ; for, — 
 
406 APPENDIX. 
 
 2 atoms crenic acid 
 
 id, I 
 
 Carbon. Hydrogen. Oxygen. 
 11 4 4 
 
 11 4 4 
 
 22 8 8 
 
 Deducting 12 Carbon, 12 
 
 Form 1 atom apocrenic, 10 8 8 
 
 " It is this change, which may account for the great evolution of 
 carbonic acid, which attends the exposure of geine to air. The 
 alkaline, earthy, and metallic bases of the silicates of soils, as 
 they are eliminated by the decomposing action of growing plants, 
 all effect catalytic changes in geine. But without these, geine 
 itself is decomposed by air and moisture, evolving volumes of 
 carbonic acid. It becomes in every and the widest sense the 
 food of plants, whether we consider it taken up as a simple solu- 
 tion of geine, or geates, or as a prolific source of carbonic acid. 
 I do not, however, consider carbonic acid as vegetable food, or as 
 playing a very important part in the nutrition of plants. Jablon- 
 ski tried to verify the idea of Raspail, and to determine how much 
 is due to the action of carbonic acid. The whole series of hia 
 most carefully conducted experiments, feeding plants only on 
 carbonic acid and water, lead to this conclusion, that carbonic 
 acid and water do not sustain plants, after the vegetable nutriment 
 deposited in albumen or the cotyledons has been exhausted. I did 
 never suppose, till I learned it from you, that any one could have 
 believed that I denied that plants absorb nourishment from air. 
 Speaking wholly of soils, and that by letter, I confined my re- 
 marks strictly to the nourishment derived from the eartli. But 
 extending the remark to air, geine is the great source of carbonic 
 acid even then, and as far as carbonic acid is absorbed by the 
 roots of plants, is perhaps its only source. I go further. I be- 
 lieve that geine was, before organic matter, an original forma- 
 tion, dating its birth from the dawning of time, when oxygen, and 
 hydrogen, and carbon, were created. I believe it to have been 
 an original formation, the source whence were nourished the gi- 
 gantic plants of coal formations, and of itself, forming a large 
 part of such deposits. Hence we find little or no alkalies in our 
 analysis of coal, — a little silica, iron, lime, and alumina only 
 having been formed as geates, in this early age. 
 
APPENDIX. 407 
 
 " I have not thought it wortli while to go into an examination of 
 the practical value, to agriculture, of the doctrine of the mixed 
 nature of geine. If it has any value, it depends entirely on 
 showing that crenic and apocrenic acids require different treat- 
 ment from geine, and on determining the proportion in which 
 these acids exist in soils. The first has not been done, the last 
 never will be effected. It cannot be. We see these acids pass- 
 ing from one to the other state even during our manipulations ; 
 how then can we determine in what proportions they existed in 
 the original soil? It may be said, that we can estimate them all, 
 as crenic acid, as Berzelius has in his analysis of the water of the 
 Porla well. In this case, so far as agriculture is concerned, we 
 may call them geine. 
 
 " With the highest regard, I am 
 
 " Your friend and servant, 
 
 « SAMUEL L. DANA. 
 "Prof. Hitchcock, .^?n/ie?*5/. 
 
 " P. S. I do not ordinarily use the oxygen scale. The state- 
 ment above being chiefly derived from Dr. Thomson, 1 have 
 employed his numbers for your convenient reference." 
 
 Dr. Jackson's Vietvs. — Geine and Humus. 
 
 Di\ Jackson is of opinion, that if there is any such matter as 
 has been called soluble geine, (see note, p. 57,) lime, by forming 
 an insoluble combination with it, would be one of the most nox- 
 ious ingredients in soil or in composts, which is directly opposite 
 to the fact as proved by experience. Dr. Jackson remarks, that 
 by actual experiment he has ascertained that but a very small 
 proportion of the soluble organic matter (called geine) is precipi- 
 table by lime-water, and that matter is only apocrenic acid. All 
 the other matters which form the largest proportion of the solu- 
 ble mould, form soluble combinations with lime.* 
 
 * According to Berzelius, subcrenate of lime is insoluble. See 
 Thomson's Organic Chemistry, p. 51. On referring to the table of 
 Hitchcock, p. 59, it will be seen that his result agrees with that of 
 Berzelius. It is obvious that care is required to avoid an excess of 
 lime and the formation of a soluble crenate. In agriculture this would 
 seem to be unavoidable, and lime to be as likely to do harm as 
 good. — TV. 
 
408 APPENDIX. 
 
 In regard to sub-soils, although not at first sight very prepos- 
 sessing in appearance, they contain, continues Dr. Jackson, a 
 large amount of the most valuable soluble matters capable of 
 nourishing plants, and the crenate of lime is much more abun- 
 dant in them, in proportion to the other organic matters, than in 
 the top-soil or mould. This he believes to have been carried 
 down by infiltration ; and on this depends the theory of sub-soil 
 ploughing. 
 
 Our well waters, according to Dr. Jackson, are often charged 
 with the soluble organic matters of the soil, the crenate of lime. 
 So also hard water with crenates of lime, ammonia, humates of 
 the same, &c. The river and pond waters of Massachusetts also 
 contain crenic acid. 
 
 Berzelius employs humus as a generic term for the organic 
 matters in soils. The reason why the organic matters in nature, 
 called humus, act so differently from artificial humic acid is, that 
 the former is not a simple organic acid, but is a complication of 
 salts, formed from decomposed organic matters, by which acids 
 are combined with alkaline, and earthy, and metallic bases. 
 Hence, when neutralized by bases, it has no acid reaction, but 
 the moment it is set free it has. 
 
 The substances which are confounded under the name of sol- 
 uble humus, soluble geine, &c., consist of 
 
 Crenic acid. Sulpliates of Soda, 
 
 Apocrenic acid. Potash, 
 
 Humic acid. Magnesia, 
 
 Extract of Humus. Lime, 
 
 Humin. Ammonia, &c. 
 
 Glalrin. Phosphates of Soda, 
 
 Soluble salts, as Ammonia, and other 
 
 Chlorides of Sodium, bases. 
 
 Calcium, Oxalates of various bases, not all 
 
 RIagnesium, ascertained, 
 and other clilorides and muriates. 
 
 We have also the acids of vegetable mould, above mentioned, 
 combined with all the usual bases found in soils, such as lime, 
 magnesia, manganese, oxide of iron, alumina, potash, soda, &c. 
 Liebig disrecrards these del ails, and calls all humus. 
 
APPENDIX. 
 
 409 
 
 Extracts from the Work of Berzelius. (C. T. J.) 
 
 Analyses of soils from Russia, Siberia, and Hungary. Soil 
 from one to two feet in depth. 
 
 A. Soil never cultivated. B. Long cultivated, and said to be 
 in an exhausted condition. C. Sub-soil of the field B. 
 
 
 ^. 
 
 B. 
 
 a 
 
 Sand, .... 
 
 51.84 
 
 53 38 
 
 52.77 
 
 f Silica, 
 
 17.80 
 
 17.76 
 
 18.65 
 
 Alumina, 
 
 8.90 
 
 8.40 
 
 8,85 
 
 Aluminous J Per Oxide of Iron, 
 matter. ' Carbonate of Lime,* 
 
 5.47 
 
 5.66 
 
 5.33 
 
 .87 
 
 .93 
 
 1.13 
 
 Magnesia, . 
 
 0.00 
 
 .77 
 
 .07 
 
 [^ Water, .... 
 
 4.08 
 
 3 75 
 
 4.04 
 
 ... V- J f Phosphoric Acid, 
 
 Acids combined <-•-,.„;„ \„:a 
 ■iu D /^\ -J r Crenic Acid, . 
 with Per Oxide of^ ^pocrenic Acid. . . 
 IronandAlumina. I^jj^^^i^^^ij^ • 
 
 .46 
 2.12 
 1.77 
 1.77 
 
 .46 
 
 1.67 
 2.34 
 
 0.78 
 
 .46 
 
 2.56 
 
 1,87 
 1.87 
 
 Extract of Humus, 
 
 3.10 
 
 220 
 
 0.00 
 
 Humin and rootlets, 
 
 1.66 
 
 1.66 
 
 1.66 
 
 99.84 
 
 99.76 
 
 99.86 
 
 Analysis by Hermann, and given in the last fasciculus of Ber- 
 zelius's Treatise on Chemistry, published in Germany, 1840. 
 Humic acid is composed of 
 
 Sprengel. Malaguti. 
 
 Carbon, . , . 58.00 . . . 57.48 = 30 atoms. 
 
 Hydrogen, . . 2.10 . . 4.76 = 30 " 
 
 Oxygen, . . . 39.90 . . . 37.76 =.= 15 " 
 
 CI. p 
 w p -. 
 o " 5 
 
 p •-'i 
 
 Difference owing to the difficulty of procuring the humic acid pure 
 from the soil. 
 
 * I am of opinion, that the carbonate of lime here reported was orig- 
 inally in the soil combined with the crenic acid in wliole or in part. 
 
 C. T. J. 
 
 Berzelius says, "animal manures become changed after a while into 
 crenic and apocrenic, humin and humic acids, in order to supply what 
 has been removed by the crops that have been taken from the soil." 
 
 35 
 
410 APPENDIX. 
 
 Animal Manure. 
 
 Animal manures become changed after a while into crenic 
 and apocrenic acids, humin, and humic acid, in order to supply 
 what has been removed by the crops that have been taken from 
 the soil. 
 
 Physiologists have often remarked that plants grow very well 
 without the presence of humus until the formation of the organs 
 of fructification, but after this has commenced and the seed 
 begins to perfect itself, they draw from the earth a large supply 
 of the constituents of the soil, and wanting these the blossoms 
 fall off without forming any seed or fruit. 
 
 The remarks of De Saussure on soils seem to show that the 
 three constituents above described, crenic, apocrenic, aud hu- 
 mic acids, by means of the reciprocal influence of water and 
 air become mutually changed. Water in moist soil changes 
 part of the insoluble humin into humic acid, so that after a suffi- 
 cient length of time the greater part of the humin becomes 
 soluble. The atmosphere on the other hand, re-forms from the 
 soluble matter, humin. Coal of humus, which in contact with 
 the air changes a portion of it into carbonic acid, is itself con- 
 verted into humin and humic acid, and this appears in fact to 
 be the useful effect of loosening the soil by tillage which ex- 
 poses it to the influence of the air. [Berzelius.] 
 
 Lime. 
 
 Berzelius thinks that lime and ashes act alike as converters 
 of mould into soluble matters which serve as food to the plants. 
 He thinks calcareous matters act also as stimuli to the plants. 
 
 Dr. Dana considers the practice of mixing lime with peat as 
 the worst that can be followed, as a compound is formed of little 
 solubility, viz. geate of lime. He recommends the ley of wood- 
 ashes, which gives a dark-brown solution, the alkaline proper- 
 ties of the lime are neutralized and a large quantity of water 
 is absorbed. See Report on Reexamination of the Geology of 
 Massachusetts, 1838, pp. CO, 88. 
 
APPENDIX. 411 
 
 Ammonia. 
 
 Dr. Jackson is of opinion that the ammoniacal salts act in 
 a different way from that stated by Liebig ; that the carbonate 
 of ammonia acts upon the organic matters of the soil, and ren- 
 ders the organic acids neutral and soluble ; decomposes and 
 renders inert, noxious metallic salts and other compounds. 
 
 Dr. Jackson objects that Liebig has not produced any in- 
 stance where a plant has been raised by a solution or other 
 preparation of ammonia in a purely siliceous or other pure 
 earthy soil. This question is, therefore, open for research, and 
 experiments have been instituted to decide it. (That ammonia 
 in the state of carbonate and in solution in water has a great 
 effect in stimulating plants, has long been known to gardeners, 
 but they also well know that the plant so treated soon perishes. 
 It would seem to be an analogous case to that of plants stimu- 
 lated by chlorine, but not supplied with a proportionally in- 
 creased allowance of food. — W.) 
 
 Root Secretions, 
 
 It should be stated that the accuracy of the experiments of 
 Macaire-Princep adduced by the author, page 209, is not gen- 
 erally admitted. Other chemists have been unable to obtain 
 similar results, or if they do, are inclined to ascribe them to 
 injury of the roots of the plants examined. Professor Lindley 
 has in his notice of Liebig's work remarked that he has no fixed 
 opinion on the subject, it being a question of facts and not of 
 induction. Admitting root secretions, he nevertheless does not 
 deem it necessary to look to the roots for these excretions, 
 when we have so many proofs of their constant occurrence in 
 other parts of a plant, as in the oily, resinous, waxy, acid and 
 acrid matter, from various parts of their surface, and in the 
 peculiar substances lodged in the hollows of their stems or else- 
 where, such as Tabasheer, in the bamboo. These are thought 
 to be instances "sufficient to satisfy the necessity of excretions 
 occurring, and to render it superfluous to look to the roots for 
 further aid in this particular." — W. 
 
412 APPENDIX. 
 
 Phosphate of Lime. 
 
 Dr. Dana has argued with great ability that phosphate of 
 lime is a constituent of all soils in their natural state. " When 
 we consider," he remarks, " that the bones of all graminivorous 
 animals contain nearly 50 per cent, of phosphate of lime, we 
 might be at liberty to infer the existence of this principle, in the 
 food, and consequently, in the soil, on which these animals 
 graze. If we look at the actual result of the analysis of beets, 
 carrots, beans, peas, potatoes, asparagus, and cabbage, we find 
 phosphate of lime, magnesia, and potash, varying from 0.04 to 
 J .00 per cent, of the vegetable." — " Let us look at the extensive 
 crops often raised where man has never manured. Rice, wheat, 
 barley, rye, and oats, all contain notable portions of phosphate 
 of lime, not only in the grain, but in the straw, and often in the 
 state of superphosphates. The diseases, too, ergot and smut, 
 show free phosphoric acid." — "Take, too, the cotton crop of 
 our country. What vast quantities of phosphates do we thus 
 annually draw from the soil ? Cotton gives one per cent, ashes, 
 of which 17 per cent, is composed of phosphate of lime and 
 magnesia. The like is true of tobacco. It contains 0.16 per 
 cent, of phosphate of lime. The pollen of the piiius abies, 
 wafted about in clouds, is composed of 3 per cent, of phosphate 
 of lime and potash. May not this be one of nature's beautiful 
 modes of supplying phosphoric acid to plants and soils ? If, as 
 the late experiments of Peschier have proved, sulphate of lime, 
 in powder, is decomposed by growing leaves, the lime liberated, 
 and the sulphuric acid combining with the potash in the plant, 
 why may not phosphate of lime, applied by pollen, act in the 
 same way ?" Dr. Dana proceeds to state the amount of phos- 
 phates in the ashes of different plants, which have been quoted 
 at page ^28. Phosphate of iron, he continues, is common in 
 turf; bog ore, and some barren and acid soils owe their acidity 
 to free phosphoric acid. If we allow that our untouched forest 
 soil contains phosphate of lime, it may be said, that this, being 
 in small quantity, will be soon exhausted by cultivation, and 
 that the phosphates, which we now find in cultivated fields, 
 rescued from the forest, are due to our manure ; — I give you 
 the general result of my analysis of cow dung, as the best argu- 
 
APPENDIX. 4 1 3 
 
 ment in reply, — in such terms as the farmer may comprehend; 
 water 83.60, hay 14, biliary matter (bile resin, bile fat, and 
 green resin of hay) 1.275 ; geine combined with potash, (veg- 
 etable extract) 0.95, albumen 0.175. 
 
 " The hay is little more altered than by chewing. The albu- 
 men has disappeared, but its green resin, wax, sulphate and phos- 
 phate of lime remain, and when we take 100 parts of dung, 
 among its earthy salts we get about 0.23 parts phosphate, 0.12 
 carbonate, and 0.12 sulphate of lime. Now a bushel of green 
 dung, as evacuated, weighs about 87.5 lbs. Of this, only 2.40 per 
 cent, are soluble. Of tliis portion, only 0.95 can be considered 
 as soluble geine." 
 
 PEAT COMPOST. 
 
 (page 231.) 
 
 According to the statement of Messrs. Phinney and Hag- 
 garston, as contained in the Report on the Geological and ^Igri- 
 mllural Survey of Rhode Island, by Dr. C. T. Jackson, a compost 
 made of three parts of peat and one of stable manure, is equal 
 in value to its bulk of clean stable dung, and is more permanent 
 in its eifects. 
 
 Dr. Jackson deems it essential that animal matters of some 
 kind should be mixed with the peat, to aid the decomposition and 
 produce the requisite gases. Lime decomposes the peat, neu- 
 tralizes the acids, and disengages the ammonia. The peat ab- 
 sorbs the ammonia, and becomes in part soluble in water. The 
 soluble matter, according to Dr. Jackson, is the apocrenate of 
 ammonia ; crenate of ammonia, and crenate of lime being also 
 dissolved. With an excess of animal matter and lime, free car- 
 bonate of ammonia is formed. 
 
 The peat should be laid down in layers with barn-yard manure, 
 night soil, dead fish, or any other animal matter, and then each 
 layer strewed with lime. In Dr. Jackson's report, he has presented 
 highly valuable results from the use of this compost, which de- 
 serves the attention of every agriculturist. He gives the follow- 
 ing details of the manner in which the compost was prepared upon 
 35* 
 
414 
 
 APPENDIX. 
 
 the farm of Mr. Sanford, near the village of Wickford in North 
 Kingston. '• In the corner of tlie field a cleared and level spot 
 was rolled down smooth and hard, and the swamp muck was 
 spread upon it, forming a bed eight feet wide, about fifteen or 
 twenty feet long, and nine inches thick. For every wagon load 
 of the muck one barrel of fish was added, and the fish were 
 spread on the surface of the muck, and allowed to become pu- 
 trescent. The moment they began to decompose, he again cov- 
 ered them with peat, and a renewed layer offish was spread and 
 covered in the same manner. The fermentation was allowed to 
 proceed for two or three weeks, when the compost was found to 
 have become fit for the land. To this he was advised to add lime 
 in the proportion of one cask to each load of compost early in the 
 spring, which it was supposed would complete the decomposition 
 in two or three weeks. Such a heap should be rounded up and 
 covered, so as to prevent the rain washing out the valuable salts, 
 that form in it. And in case of the escape of much ammonia, 
 more swamp muck or peat should be spread upon the heap, for 
 the purpose of absorbing it. Dr. Jackson is of opinion that the 
 phosphoric acid of the peat and animal matter would convert the 
 lime into a phosphate, and thus approximate it very closely to 
 bone manure." — Report, p. 170. 
 
 Any refuse animal matter can be, of course, employed in a 
 similar manner. " The carcase of a dead horse, which is often 
 suff'ered to pollute the air by its noxious effluvia, has been 
 happily employed in decomposing 20 tons of peat earth, and 
 transforming it into the most enriching manure." — Young's Let- 
 ters of ^gricola,Lietter 25, p. 238.* 
 
 Night soil may be composted with peat with great advantage, 
 sufficient lime being added to deprive it of odor; large quanti- 
 ties of ammonia are given off and absorbed.f 
 
 * In a Report on a Reexamination of the Geology of Massachu- 
 setts, J 838, Dr. Dana particularly notices the evohition of ammonia 
 from fermenting dung, and supposes that the ammonia combines with 
 geine to form a soluble compound. Sec JS'otc to page 83 of the Re- 
 port. 
 
 t JVight Soil. The quantity of night soil collected and removed from 
 the city of Boston annually, is about four hundred thousand square feet. 
 
APPENDIX. 415 
 
 Appended to Dr. Jackson's report will be found a letter from 
 E. Phinney, Esq., of Lexington, well known as one of the most 
 skilful agriculturists, On the reclaiming of peat bogs and the em- 
 ployment of peat as manure. 
 
 COLLECTION AND USE OF MANURE IN CHINA. 
 
 (Extract from the communication referred to at page 242.) 
 
 " Human urine is, if possible, more husbanded by the Chinese 
 than night soil for manure ; every farm, or patch of land for cul- 
 tivation, has a tank where all substances convertible into manure 
 are carefully deposited, the whole made liquid by adding urine 
 in the proportion required, and invariably applied to the soil in 
 that state. The business of collecting urine and night soil 
 employs an immense number of persons, who deposit tubs in 
 every house in the cities for the reception of the urine of the in- 
 mates, which vessels are removed daily with as much care as our 
 farmers remove their honey from the hives. The night soil is 
 collected in the same way, as well as on the roads and by- 
 places, persons being always on the alert with baskets and 
 rakes to avail of the least particle that appears. The Chinese 
 get as much off their land, as it is capable of producing, and this 
 is done by the liberal use of manure, and application of much 
 more labor in working the soil than in other countries. The reason 
 they do not use dung is, that they have comparatively no animals; 
 horses and cattle are so rare, that every thing except plough- 
 ing, which is done with the buffalo, is accomplished by manual 
 labor." 
 
 It is used by cultivators in the immediate vicinity, being composted 
 with soil, lime, peat, &c. Large quantities of animal matter from 
 slaughter houses, and other sources, are also made use of. The heaps 
 are left exposed, uncovered to the air, and the value of the compost is 
 consequently greatly diminished. See page 242. 
 
416 APPENDIX. 
 
 ADDITION TO NOTE AT PAGE 70. 
 
 If the atmosphere possessed, in its whole extent, the same 
 density as it does on the surface of the sea, it would have a 
 height of 24.555 Parisian feet ; but it contains the vapor of 
 water, so that we may assume its height to be one geographical 
 mile = 22,843 Parisian feet. Now, the radius of the earth is 
 equal to 860 geographical miles ; hence the 
 
 Volume of the atmosphere =9,307,500 cubic miles = cube of 210.4 
 
 miles. 
 Volume of oxygen = 1,954,578 cubic miles =cube of 125.0 miles. 
 Volume of carbonic acid = 3,862.7 cubic miles = cube of 15.7 miles. 
 
 The maximum of the carbonic acid contained in the atmo- 
 sphere has not been here adopted, but the mean, which is equal 
 to 0.000415. 
 
 A man daily consumes 45,000 cubic inches (Parisian). 
 
 A man yearly consumes 9505.2 cubic feet. 
 
 1,000 million men yearly consume 9,505,200,000,000 cubic 
 feet. 
 
 1 cubic mile is equal to 11,919,500,000,000 cubic feet. 
 
 Hence a thousand million men yearly consume 0.79745 cubic 
 miles of oxygen. But the air is rendered incapable of support- 
 ing the process of respiration, when the quantity of its oxygen is 
 decreased 12 per cent. ; so that a thousand million men would 
 make the air unfit for respiration in a million years. The con- 
 sumption of oxygen by animals, and by the process of combus- 
 tion, is not introduced into the calculation. 
 
 TABLES 
 
 SHOWING THE PROPORTION BETWEEN THE HESSIAN AND ENG- 
 LISH STANDARD OF WEIGHTS AND MEASURES. 
 
 As the numbers throughout the work have been stated in ref- 
 erence to some common measure, it has been thought advisable 
 not to state the English equivalents to the Hessian numbers in 
 the text, lest they should distract the attention of the reader by 
 
APPENDIX. 417 
 
 being placed in decimals. The numbers do not represent abso- 
 lute quantities, but are merely intended to denote a proportion to 
 other numbers ; so that it is quite indifferent in what standard of 
 weights or measures they are stated. In almost every case where 
 the term " Hessian pounds," is employed, the word " parts " 
 may be substituted. For those, however, who wish to be ac- 
 quainted with the exact English quantities, a table is given be- 
 low. 
 
 1 lb. English is equal to 0.90719 lbs. Hessian ; hence about 
 one tenth less than the latter. 
 
 2 lbs 
 
 1. Hessian are equal to 
 
 2.20 lbs. 
 
 English. 
 
 3 
 
 (c 
 
 (( 
 
 3.306 
 
 (( 
 
 4 
 
 <( 
 
 « 
 
 4.409 
 
 « 
 
 5 
 
 i( 
 
 (( 
 
 5.51 
 
 tt 
 
 6 
 
 (( 
 
 << 
 
 6.61 
 
 tt 
 
 7 
 
 (1 
 
 « 
 
 7.716 
 
 << 
 
 8 
 
 (( 
 
 ct 
 
 8.818 
 
 <( 
 
 9 
 
 (< 
 
 tl 
 
 9.92 
 
 tt 
 
 10 
 
 tt 
 
 « 
 
 11.02 
 
 tt 
 
 20 
 
 (( 
 
 « 
 
 22.04 
 
 " 
 
 30 
 
 <( 
 
 « 
 
 33.06 
 
 c< 
 
 40 
 
 (( 
 
 « 
 
 44.09 
 
 (( 
 
 50 
 
 (( 
 
 « 
 
 55.11 
 
 " 
 
 60 
 
 (1 
 
 (( 
 
 66.12 
 
 (( 
 
 70 
 
 C( 
 
 <( 
 
 77.16 
 
 (( 
 
 80 
 
 (( 
 
 « 
 
 88.18 
 
 " 
 
 90 
 
 <1 
 
 <c 
 
 99.29 
 
 ti 
 
 100 
 
 11 
 
 (( 
 
 110.2 
 
 tl 
 
 200 
 
 t( 
 
 (( 
 
 220.4 
 
 ti 
 
 300 
 
 <( 
 
 (l 
 
 330.6 
 
 " 
 
 400 
 
 <( 
 
 a 
 
 440.9 
 
 it 
 
 500 
 
 (( 
 
 it 
 
 551.1 
 
 ti 
 
 600 
 
 (( 
 
 tt 
 
 661.2 
 
 tl 
 
 700 
 
 (( 
 
 It 
 
 771.6 
 
 11 
 
 800 
 
 (( 
 
 tt 
 
 881.8 
 
 " 
 
 900 
 
 It 
 
 tt 
 
 992.9 
 
 tl 
 
 [000 
 
 « 
 
 (( 
 
 1102.0 
 
 u 
 
418 
 
 APPENDIX, 
 
 SQUARE FEET. 
 
 The Hessian acre is equal to 40,000 Hessian square feet, or 
 26,917 English square feet ; one English square foot being equal 
 to 1.4864 Hessian. The following is a Table to save the trouble 
 of calculation. The Table is only stated to the figure 10, but by 
 removing the decimal point one or two figures, the whole series 
 given in the case of the pounds will also be obtained. 
 
 2 square feet Hessian are equal to 1.345 square feet English. 
 
 3 
 
 
 2.011 
 
 4 
 
 
 2.691 
 
 5 
 
 
 3 363 
 
 6 
 
 
 4.036 
 
 7 
 
 
 4.709 
 
 8 
 
 
 5.382 
 
 9 
 
 
 6.054 
 
 10 
 
 
 6.727 
 
 
 CUBIC 
 
 FEET. 
 
 One English cubic foot contains 1.81218 of a Hessian cubic 
 foot ; the Hessian and English cubic inch may be considered as 
 equal, one English cubic inch containing 1.048715 Hessian cu- 
 bic inch. 
 
 1 cubic foot Hessian is equal to 0.551 cubic foot English. 
 
 2 feet " " 
 
 3 «' " 
 
 4 
 5 
 6 
 
 7 
 
 8 
 
 9 
 
 10 
 
 1.103 
 1.655 
 2.207 
 2.759 
 3.311 
 3.863 
 4.415 
 4.966 
 5.518 
 
 feet 
 
APPENDIX. 
 
 419 
 
 TABLE OF THE CORRESPONDING DEGREES ON THE SCALES OF 
 FAHRENHEIT, REAUMUR, AND CELSIUS, OR CENTIGRADE. 
 
 
 
 6 
 
 
 3 
 
 Pi 
 
 
 
 3 
 nJ 
 
 
 212 
 
 80 
 
 100 
 
 149 
 
 52 
 
 65 
 
 50 
 
 8 
 
 10 
 
 203 
 
 76 
 
 95 
 
 140 
 
 48 
 
 60 
 
 41 
 
 4 
 
 5 
 
 194 
 
 72 
 
 90 
 
 131 
 
 44 
 
 55 
 
 32 
 
 
 
 
 
 185 
 
 68 
 
 85 
 
 122 
 
 40 
 
 50 
 
 23 
 
 — 4 
 
 — 5 
 
 176 64 
 
 80 
 
 113 
 
 36 
 
 45 
 
 14 
 
 — 8 
 
 — 10 
 
 167 60 
 
 75 
 
 104 
 
 32 
 
 40 
 
 5 
 
 — 12 
 
 — 15 
 
 158 
 
 56 
 
 70 
 
 95 
 
 28 
 
 35 
 
 4 
 
 — 16 
 
 — 20 
 
 
 
 
 86 
 
 24 
 
 30 
 
 — 13* 
 
 — 20 
 
 — 25 
 
 
 
 
 77 
 
 20 
 
 25 
 
 — 22 
 
 — 24 
 
 — 30 
 
 
 
 
 68 
 
 16 [20 
 
 — 31 
 
 — 28 
 
 — 35 
 
 
 
 
 59 
 
 12 15 
 
 — 40 
 
 — 32 
 
 — 40 
 
 — Denotes below the cipher on Fahrenheit's scale. 
 
INDEX. 
 
 ACI 
 Absolute weight, 3. 
 
 Jlbsorpd'jn by roots, 147. 
 
 of salts, 157. 
 Acid, acetic, 95. 
 
 emitted by plants, 194. 
 
 transformation of, 267. 
 
 formation of, 293 - 297. 
 
 apocrenic, 5d. 
 
 benzoic, 138. 
 
 boracic, 164. 
 
 carbonic, 70. 
 
 decomposed by plants, 
 
 73. 
 
 injurious to plants, 119. 
 
 from respiration, 71. 
 
 why necessary to plants, 
 
 147. 
 
 crenic, 58. 
 
 cyanic, transformation of, 271. 
 
 formic, 112, 127,251. 
 
 hippuric, 138. 
 
 humic, 60. 
 
 properties of, 63. 
 
 hydrocyanic, 110, 251. 
 
 hyponitrous, 55. 
 
 kiiiic, 155. 
 
 lactic, 236. 
 
 production of, 284. 
 
 nieconic, 155, 
 
 melanic, 289. 
 
 mellitic, 104. 
 
 nitric, 55. 
 
 source of, 129. 
 
 organic, action of upon car- 
 bonate of silver, 256. 
 
 phosphoric, in ashes of plants, 
 200. 
 
 rocellic, in plants, 149. 
 
 silicic, 215. 
 
 succinic, 104. 
 
 sulphuric, action of on soils, 
 247. 
 
 36 
 
 ALD 
 
 Acid, tartaric in grapes, 149. 
 Acids, what, 13. 
 
 action of upon sugar, 264. 
 
 arrest decay, 338. 
 
 equivalents of, 35. 
 
 organic, in plants, 55, 148. 
 
 when formed, 80. 
 
 oxygen, .35. 
 
 retard decay, 102. 
 
 saturating power of, 47. 
 Acid salts, 48. 
 Adipocire, 129. 
 Affinity, 6, 15, 109. 
 
 action of, 7. 
 
 chemical, examples of, 253. 
 
 increase of, 23. 
 
 predisposing, 24. 
 
 weak, example of, 254. 
 Agave Americana, absorbs oxvffen, 
 
 80. ^^ 
 
 Agriculture in China, 240. 
 
 object of, 141, 189,217. 
 
 • how attained, 189. 
 
 its importance, 187. 
 
 a principle in, 233. 
 Air, access of, favored, 106. 
 
 carbon in the, 72. 
 
 carbonic acid in, 71. 
 
 decomposed by plants, 
 
 72. 
 
 quantity extracted, 75. 
 
 effect of upon juices, 293. 
 
 from decay of woody fibre, 
 95. 
 
 improved by plants, 77. 
 
 necessary to plants, 172. 
 Albumen, 137. 
 Alcohol, effect of heat on, 267. 
 
 exhaled, 113. 
 
 products of its oxidation, 290. 
 
 from sugar, 275. 
 Aldehyde, 290. 
 
AMM 
 
 422 
 
 ASH 
 
 Alkalies, 14,50, 110, 
 
 evolve nitrogen, 270. 
 
 from granite soils, 158. 
 
 presence of indicated, 198. 
 
 promote decay of wood, 102. 
 
 quantity removed from air, 
 1G2. 
 
 in aluminous minerals, 
 
 192. 
 Alkaline bases, in plants, on what 
 their existence depends, 153. 
 * salts in plants, sources of, 195. 
 Mkargen, 342. 
 Alloxan, 319. 
 Alloxantin, 320. 
 Almonds, bitter, oil of, 2S8. 
 Alternation of crops, advantages of, 
 214. 
 
 produces humus, 217. 
 AlthecB, 93. 
 Alumina, in fertile soils, 191. 
 
 its influence on vegetation,191. 
 Amber, origin of, 104. 
 Ammonia, carbonate of, from urine, 
 237. 
 
 how fi.Ked, 238. 
 
 cause of nitrification, 303. 
 
 changes colors, 128. 
 
 condensed by charcoal, 146. 
 
 conversion of into nitric acid, 
 301. 
 
 decomposed by gypsum, 142. 
 
 by manganese, &c., 301. 
 
 detected, 132,238. 
 
 early existence of, 165. 
 
 fixed by gypsum, 142. 
 
 from animals, 219. 
 
 beet root, «&c., 135. 
 
 hydrocyanic acid, 111. 
 
 maple juice, 134. 
 
 stables, 239. 
 
 furnishes nitrogen, 146. 
 
 liberated, 270. 
 
 loss from evaporation, 246. 
 
 most stable compound of ni- 
 trogen, 270. 
 
 neutralized, 375. 
 
 nitrate of formed, 301. 
 
 not formed on cultivated land, 
 217. 
 
 produced by animal organism, 
 165. 
 
 product of decay, 129. 
 
 of disease, 374. 
 
 properties of, 127 
 
 quantity absorbed by charcoal, 
 146. 
 
 Ammonia, quantity absorbed by de- 
 cayed wood, 146. 
 
 in rain water, 130 - 132. 
 
 separated by rain, 146. 
 
 in snow water, 132. 
 
 solubility of, 130. 
 
 transformation of, 127. 
 
 water from, 302. 
 Ammoniacal salts, their mode of ac- 
 tion, 411. 
 Amylin, its effect, 114. 
 Analysis of decayed wood. 326. 
 
 of fire damp, 334. 
 
 of oak wood, 99, 100. 
 
 of salt water, 166. 
 
 of soils by Berzelius, 409. 
 Animal food, preservation of, 294. 
 
 life, connexion of, with plants, 
 73. 
 
 bodies, decay of, product of 
 the, 129. 
 Animals, analysis of their bones, 203. 
 
 elements that support, 147. 
 
 excrements of, 139, 220. 
 
 fattening of, 190. 
 
 whence they derive phospho- 
 ric acid, 201. 
 
 concretions in, 201. 
 
 putrefaction of, 219. 
 Animal excrement, its chemical na- 
 ture, 220. 
 
 manuie, 410. 
 Annual plants, how nourished, 178. 
 Antkuxanthum odoratum, acid in, 
 
 139. 
 Anthi acite, 334. 
 Antidotes to poisons, 343. 
 Apatite, 201. 
 Apotkeme, 57. 
 
 quantity in wheat, 58. 
 Appcrt's method of preserving, 318. 
 Aqiiic fortis, 55. 
 Arable land, 190. 
 
 Aromatics, their influence on fer- 
 mentation, 309. 
 Argillaceous earth, its origin, 191. 
 Arragonitc, transformation of, 258. 
 Arsenious acid, action of, 241. 
 Ashes, as manure, 227. 
 
 phosphates in, 412. 
 
 comparative value of, 228. 
 
 of fire wood, 64. 
 
 of pine trees, 151. 
 
 of plants, origin of salt in, 166. 
 
 importance of examination of, 
 153. 
 
 of wheat, 203. 
 
BEE 
 
 423 
 
 BUT 
 
 Ashes, of bones, 227. 
 
 of peat, 230. 
 Assimilation of carbon, 77-85. 
 
 of carbonic acid and ammo- 
 nia, 174. 
 
 of hydrogen, 120. 
 
 of nitrogen, 126. 
 
 most active in woody fibre, 
 148. 
 
 requires nitrogen, 181. 
 
 its power, 184. 
 Atmosphere, composition of, 55. 
 
 how maintained, 74 - 76. 
 
 proportion is invariable, 70. 
 
 carbonic acid in, 74. 
 
 moisture to plants from, 118. 
 
 motion of, 76. 
 
 nitrogen from, 129. 
 
 oxj'gen given to by land, 121. 
 Atovis, motion of, 257. 
 
 permanence in position of, 
 258. 
 Atomic theory, 38. 
 Attraction, 2. 
 
 chemical, 4. 
 
 powerful, overcome, 271. 
 Azores, springs containing silica, 215. 
 Azotized matter in juices of plants, 
 181. 
 
 substances, combustion of, 
 299. 
 
 formation of nitrates without, 
 302. 
 
 Balance, 3. 
 
 Bamboo, silica in, 216. 
 
 Barilla, 160. 
 
 £arA; of trees, products in, 78. 
 
 Barley, analysis of, 199. 
 
 Barruel, his experiments on blood, 
 
 368. 
 Base, what, 110. 
 
 Bases, alkaline in plants, on what 
 their existence depends, 
 153. 
 
 organic, 56. 
 
 oxygen, 35. 
 
 in plants, 148. 
 
 substitution of, 149. 
 Basic salts, 47. 
 Beans, alkalies in, 204. 
 
 nutritive power of, 204. 
 Becquerel, experiments of, 194. 
 Beech, ashes of, 228. 
 Beer, 309. 
 
 Bavarian, 314. 
 
 varieties of, 314. 
 
 Beet root sugar, 67. 
 
 ammonia from, 135. 
 
 from sandy soil, 184. 
 Benignant disease, 368. 
 Benzoic acid, 138. 
 
 formed, 288. 
 Benzule, 138. 
 Bergstrasse, 171. 
 Berzelius, his discovery of crenic 
 
 acid, «&c., 58. 
 
 his analysis of faeces, 225. 
 
 of soils, 409. 
 
 on mode of action of lime, 
 410. 
 Binary compounds, 13. 
 Binoxide of nitrogen, 55. 
 Birch tree, ammonia from, 135. 
 Bleaching salts, 143. 
 Blood, its office, 178. 
 
 action of chemical agents up- 
 on, 361. 
 
 its feeble resistance to exte- 
 rior influences, 360. 
 
 organic salts in, 337. 
 
 its character, 349. 
 Blossoms, when produced, 108. 
 
 increased, 175. 
 
 removal of from potatoes, 177. 
 Bodies, amorphous, 18. 
 
 compound, 13. 
 
 condition of, changed, 259. 
 
 decomposition of, 25. 
 
 containing nitrogen, transfor- 
 mation of, 266 - 269. 
 
 gaseous, union of, 39. 
 
 properties of, 8. 
 
 simple, 12. 
 
 weight and volume of, 41. 
 Body, defined, 1. 
 Bones, analysis of, 202. 
 
 durabihty of, 246. 
 
 gelatine in, 246. 
 Bone ashes, 227, 
 
 manure, 229. 
 Bouquet of wines, 311. 
 Boracic acid, 164. 
 Botanists, neglect of chemistry by, 
 
 85. 
 Brandy from corn, 308. 
 
 oil of, 310. 
 Brazil, wheat in, 198. 
 Bread from wood, 175. 
 Broion coal, 325. 
 
 ashes of, 230. 
 Buckwheat, ashes of, 204. 
 Bulbs, how nourished, 117. 
 Butter, contains hydrogen, &c., 91. 
 
CAR 
 
 424 
 
 COA 
 
 Calcareous SPAR, 258. 
 
 Calcium, fluoride of, 202. 
 Calculous disorders, 115. 
 Calico printing, use of cow dung in, 
 
 232. 
 Caloric, 9. 
 
 Caoutchouc in plants, 118. 
 Carbon, 54. 
 
 absorbed by roots, 75. 
 
 afforded to the soil by plants, 
 116. 
 
 assimilation of, 57, 77, 85. 
 
 combination of, with oxygen, 
 2ti7. 
 
 of decaying substances, sel- 
 dom affected by oxygen, 
 286. 
 
 derived from air, 72, 74. 
 
 in decaying wood, 100. 
 
 in decayed woody fibre, 77. 
 
 in sea- water, 74. 
 
 oxide of, formed, 267. 
 
 quantity in grain, «fec., 67. 
 
 in land, 68. 
 
 in straw, CD. 
 
 restored to the soil, 116. 
 
 received by leaves, 75. 
 
 in sugar, 275. 
 
 its affinity for oxygen, 291. 
 Carbonate of ammonia decomposed 
 by gypsum, 142. 
 
 lime in caverns and vaults, 
 169. 
 
 from urine, 237. 
 
 how fixed, 238. 
 Carbonic acid changes in leaves, 186. 
 
 in air, 71,74, 167. 
 
 decomposed by plants, 72, 186. 
 
 effect of, on corn, 119. 
 
 emission of, at night, 83. 
 
 from the earth, 173. 
 
 evaporation of, 84. 
 
 its evolution from decay of 
 bodies, 292. 
 
 from decaying plants, 126. 
 
 respiration, 113. 
 
 excrements, 140. 
 
 humus, 117. 
 
 springs, 126. 
 
 woody fibre, 95. 
 
 increase of, prevented, 71. 
 
 influence of light on its de- 
 composition, 83. 
 
 transformation of, 186. 
 
 quantity from air, 75. 
 
 in springs, 330. 
 
 in water, decomposed, 85. 
 
 Carbonic acid, nutrition of plants by, 
 87. 
 
 source of, 105. 
 
 when injurious, 119. 
 Carburetted hydrogen with coal, 333. 
 Catalyctic force, 44. 
 
 objections to, 45. 
 Catahjlism, 42, 44. 
 Caverns, stalactites in, 170. 
 Charcoal, condenses ammonia, 146. 
 
 experiments of Lukas and 
 Buchner, 119. 
 
 may replace humus, 119. 
 
 theory of its action, 119. 
 
 promotes growth of plants, 
 247. 
 
 spontaneous combustion of, 
 287. 
 Chemical attraction, 4. 
 
 affinity, 380. 
 
 effects of light, 185. 
 
 forces can replace the vital 
 principle, 11-5. 
 
 processes in nutrition of veg- 
 etables, 53. 
 
 properties of bodies, 8. 
 
 proportion, laws of, 32. 
 
 transformations, 109, 249. 
 Chemist, his duly, 190. 
 Chemistry, organic, what, 53. 
 
 neglected by botanists, 85. 
 
 and physiologists, 86. 
 
 Chinese, manure collected by the, 
 240. 
 
 and prepared, 241. 
 
 China, its agriculture, 240. 
 
 collection and use of manure 
 in, 415. 
 Chlorine, its effect, 143. 
 
 decomposes water, 184. 
 
 salts, 50. 
 
 and hydrogen, 185. 
 Chloride, what, 13. 
 
 of calcium, 143. 
 
 of nitrogen, 254. 
 
 of potassium, its effect, 156. 
 Cinchona, acid in, 155. 
 Clay, as manure, 144. 
 
 burned, advantages of, as ma- 
 nure, 144. 
 Clays, potash in, 192. 
 Clay slate, 202. 
 Coal, formation of, 325. 
 
 plants in, 117. 
 
 inflammable gases from, 333. 
 
 origin of substances in, 104. 
 
 of humus, 57, 172. 
 
CRO 
 
 425 
 
 DEN 
 
 Coal, wood, 327. 
 Cohesion, 4. 
 
 of fluids and gases, 5. 
 
 influence of, 22. 
 Colors of flowers, 13ri. 
 Combinalion, chemical, 24, 22, 109. 
 
 influenced, 23. 
 Combinations tliat undergo fermen- 
 tation and putrefaction, 265. 
 Combining-pi-oportions, 121. 
 Combustion, 7. 
 
 removes oxygen, 72. 
 
 at low temperatures, 291 . 
 
 of decayed wood, 103. 
 
 induction of, 296. 
 
 spontaneous, 287. 
 Composition, chemical, connexion 
 
 of, with form, 42. 
 Compost, for grass, 160. 
 
 of peat, 160. 
 Compounds, binary, 13. 
 
 classes of, l3. 
 
 new, how produced, 212. 
 
 organic, composition of, 123. 
 
 triple, decomposition of, 31. 
 
 conditions for forming, 22. 
 Cold meat, its state, &c., 369. 
 Concretions from horses, 201. 
 Constituents of plants, 202. 
 
 what, 7. 
 
 ultimate, 13. 
 Contagion, reproduction of, on what 
 dependent, 370. 
 
 susceptibility to, how occa- 
 sioned, 369. 
 Contagions, 335. 
 
 propagation of, 363. 
 Contagious matters, action of, 363. 
 
 their effects explained, 353. 
 
 life in, disproved, 361. 
 
 reproduction of, 366. 
 Copper, alloy of, its action on sul- 
 phuric acid, 253. 
 Corn brandy, 308. 
 
 how cultivated in Italy, 197. 
 
 phosphate of magnesia in, 
 200. 
 Corrosive sublvmate, its use, 102. 
 
 action of, 341. 
 Cow, excrement of, 221. 
 
 urine of, 222. 
 
 rich in potash, 244. 
 
 Coto pox, action of vims of, 371, 
 Crops, interchange of, 206. 
 
 favorable effect of; 208. 
 
 causes, 2l4. 
 
 Crops, principles regulating, 219. 
 Crystals, what, 15. 
 
 obtained, 17. 
 
 increased, 19. 
 
 isomorphous, 18. 
 Crystallization, 15. 
 
 water of, 20. 
 Cultivation, its benefits, 77. 
 
 different methods of, 188. 
 
 object of, 141, 105. 
 Culture, art of, 169. 
 
 of plants, principles of the, 
 189. 
 Cyanic acid, transformation of, 271. 
 Cyanogen, 110. 
 
 combustion of, 300. 
 
 transformation of, 272. 
 
 D^NA, Dr. S. L., on geine, 59. 
 on the decay of plants, 96. 
 on phosphates in soil, 228. 
 on the existence of phosphate 
 
 of lime in soils, 4l2. 
 on the action of lime, 410. 
 on evolution of ammonia, 
 414. 
 Davis, his account of Chinese ma- 
 nure, 241. 
 Daubeny, Professor, his theory of 
 origin of ammonia, in 
 springs, 133. 
 Death from nutritious substances, 90. 
 the source of life, 147. 
 of animals, changes produced 
 by, 219. 
 DecandoUe, his theory of excretion, 
 2(17. 
 difference between his views 
 and those of Macaire-Prin- 
 cep, 212. 
 Decay, 95, 2(i0. 
 
 a source of ammonia, 129. 
 of wood, 96, 101. 
 
 promoted, 102. 
 
 of plants restores oxygen, 125. 
 and putrefaction, 252. 
 Decomposing body, its effect, 348. 
 Decomposition, 25, 109, 249. 
 organic chemical, 251. 
 partial, 26. 
 influenced, 29. 
 of triple compounds, 31. 
 results of, influenced, 299. 
 of wood, 327. 
 Decrepitation, 18. 
 Density, 2. 
 
 36* 
 
ESP 
 
 42G 
 
 FLE 
 
 Derbyshire spar, 202. 
 
 De Saussure, his experiments, 79. 
 
 28!), 2'JG. 
 Development of plants, 187. 
 Dextrine, 87. 
 Diamond, 54. 
 
 its origin, 104. 
 Diastase, 17!/, 378. 
 
 contains nitrogen, 180. 
 Digestion and assimilation, 182. 
 Disease, how excited, 3G4, 367. 
 Diseases of trees, 181. 
 Dissection, wounds received in, 350. 
 Distillation, dry, 284. 
 Z)oo-, excrement of the, 220. 
 Double salts, 47. 
 Dry distillation, 284. 
 Ductile bodies, 5. 
 Dung reservoirs, 237. 
 
 analysis of, 413. 
 
 hills, liquid from, 238. 
 
 EARTHS, 5\. 
 
 Ebony wood, oxygen and hydrogen 
 
 in, 82. 
 Effete matters, separated, 109. 
 Efflorescence, 20. 
 Eggs, development of, 180. 
 Elasticity, 5. 
 Electrical action, 253. 
 Elements, 12. 
 
 of plants, 53. 
 
 not generated by organs, 90. 
 
 supporting animals, 147. 
 
 their source, how known, 94. 
 Elms, excretions of, 78. 
 Enamel of teeth, 203. 
 Equilibrium of attractions disturbed, 
 
 2G6. 
 Equivalent, its meaning, 34, 121. 
 EquisetacecE contain silica, 216. 
 Eremacausis, 95, 259, 285. 
 
 arrested, 286. 
 
 conditions for, 285, 296. 
 
 analogous to putrefaction, 292. 
 
 differs from putrefaction, 302. 
 
 of bodies destitute of nitrogen, 
 293, 
 
 necessary to nitrification, 303. 
 
 substances that undergo it, 
 287. 
 
 of bodies containing nitrogen, 
 299. 
 Erfurt, quantity of raiu at, 65. 
 Ergot and smut, 412. 
 Esparsette, cultivation of, its advan- 
 tage, 217. 
 
 Ether, cenanthic, 306, 
 Eudiometer, 131. 
 
 Excrementitious matter, composition! 
 of, various, 1 13. 
 
 production of, illustrated, 112. 
 Excrement, animal, its chemical na- 
 ture, 220. 
 
 of the dog, cow, &c., 221. 
 
 influence of, as manure, 225. 
 Excrements, animal, 207, 211. 
 
 of plants, 211. 
 
 conversion of, into humus,214. 
 
 of man, amount of, 242. 
 
 value of, 235. 
 
 preparation of, 243. 
 Excretion, organs of, 113. 
 Exciter, its effect, 3-18. 
 Excretions of elms, &c., 78. 
 
 of plants, theory of, 207. 
 Experiments in physiology, object of, 
 88. 
 
 of physiologists, not satisfac- 
 tory, 92. 
 Extract of humus, 57. 
 
 FALLOW, changes from, 197. 
 
 crops, 204. 
 
 time, 204. 
 Fattening of animals, 190. 
 Faces, analysis of, 225. 
 Ferment, 277, 'M)A. 
 Fermentation, 95, 259, 261. 
 
 of Bavarian beer, 316. 
 
 of beer, 214. 
 
 cause of, 261, 282. 
 
 Gay-Lussac's experiments, 
 294. 
 
 of sugar, 275. 
 
 results of, 274. 
 
 of veijetable juices, 276. 
 
 how excited, 279. 
 
 vinous, 303. 
 
 of wort, 30.5. 
 Fertility of fields, ho w preserved, 226. 
 
 increased, 173. 
 
 diminished, 196. 
 Fibril, radical, how regarded, 105. 
 Fibrine, 222. 
 
 Ficus JIustralis, growth of, 383. 
 Fire of London, plants after it, 199. 
 Fire-dump, 333. 
 
 Fir-ioood, analysis of its ashes, 152. 
 Fishes in salt pans, 163. 
 Flandirs, manure used in, 240. 
 Fleabane, 205. 
 Flesh, analysis of, 222. 
 
 effect of salt on, 338. 
 
GRA 
 
 427 
 
 HUM 
 
 Flour, bran of, 148. 
 
 Flowers, colors of, due to ammonia, 
 
 133. 
 Fluid, defined, 1. 
 Fluorides, 202. 
 Fluorine, 202. 
 
 salts of, 50. 
 Food, effect of too great supply of, 
 90. 
 effect on products of plants, 
 
 183. 
 its influence, 187. 
 of plants, 180. 
 . how received, 104. 
 of young plants, 174. 
 transformation and assimila- 
 tion of, 113. 
 Form, external, connexion of, with 
 
 composition, 42. 
 Formation of wood , 181 . 
 Formic acid, 111. 
 
 theory of its formation, 112, 
 
 2.51. 
 from hydrocyanic acid, 273. 
 Formula for elements of wood, 101. 
 Fossil resin, origin of, 104. 
 France, preparation of excrements in, 
 
 243. 
 Franconia, caverns in, 170. 
 Fruit increased, 175. 
 
 ripening of, 124. 
 
 changes attending, 175. 
 
 Fulminating silver, 254. 
 
 compounds, effect of motion, 
 &c., on, 379. 
 Fusing point, 11. 
 
 GjiSEOUS substances in the luncrs, 
 
 effect of, 373. 
 Gasterosteus aculeatus in salt pans, 
 
 163. 
 Gay-Lussac, his experiments, 294. 
 Geraniums, effects of chlorine on, 
 143. 
 soil for, 143. 
 Germany, cultivation in, 226. 
 Germination of potatoes, 176. 
 
 of grain, 179. 
 Glass, as rnanuie, 233. 
 Glue, manure from, 230. 
 Gluten, conversion of, into yeast, 319 
 -348. 
 decomposition of, 283,304. 
 gas fioin, 3(i4 
 Grain, germination of, 179. 
 
 harvest of, in Germany, 160. 
 manure for, 160. 
 
 Granite soil, affords alkalies, 153. 
 Grapes, compost for, 160. 
 
 constituents of the seeds, 148. 
 
 fermentation of their iuice, 
 294. 
 
 juice of, differences in, 312. 
 
 polash in, 153. 
 Grasses, seeds of, follow man, 162. 
 
 silica in, 158. 
 
 valued in Germany, 159. 
 Grauwack^, soil from, 191 
 Green principle of leaves, 218. 
 Growth of plants, conditions for the, 
 188. 
 
 without mould, 383. 
 Guano, 244. 
 Gwm, influence of, on development of 
 
 plants, 177. 
 Gypsum, decomposition of, 144, 282. 
 
 its influence, 142. 
 
 use of, 238. 
 
 H^MATIN, 289. 
 
 Haggerston, Mr., his compost, 160. 
 
 HaUiydrates, 48. 
 
 Haloid salts, 59. 
 
 Hard icater rendered soft, 133. 
 
 Hay, carbon in, 67. 
 
 composition of, 67. 
 
 contains nitrogen, 222. 
 
 silica in, 200. 
 Haystack, effect of lightning upon, 
 
 200. 
 Heat, action of, 9. 
 
 free, 11. 
 
 specific, 12. 
 Hermann, his analysis of humic acid, 
 
 409. 
 Hessian and En<rlishfeet, 418. 
 
 cubic feet, 418. 
 
 Hcteromorphuus crystals. 17. 
 Hibernating animals, 177. 
 H'ppuric acid, 138. 
 Hitchcock, Professor, his table of 
 
 geine in soils, 59. 
 Honey dew, 181. 
 Horse, urine of, 143. 
 
 carcase of, its use, 414. 
 Horses, concretions in, 201. 
 Horse-chestnut, excretions of, 78. 
 Horse-dunif, action of water upon, 
 223. 
 
 analysis of, 223. 
 Humanfaces, analysis of, 225 
 Humute of time, quantity received by 
 
 plants, 66. 
 Humic acid, 57, 60. 
 
INS 
 
 428 
 
 LIG 
 
 Hiimic acid, action of, 171. 
 
 properties of, 63. 
 
 in wheat, 65. 
 
 quantity received by plants, 
 Go. 
 
 its nutritive office, 66. 
 
 in excretions of oaks, &c., 78 
 
 insolubility of, 170. 
 Humic extract, 62. 
 
 acid, analysis of, 409. 
 Ilumin, ^)7. 
 Humus, 57, 96. 
 
 action of, 106. 
 
 erroneous opinion of, 78. 
 
 action upon oxygen, 170. 
 
 coal of, 57, 172. 
 
 conversion of woody fibre in- 
 to, 98. 
 
 how produced, 99. 
 
 its insolubility, 169. 
 
 nourishes plants, 174. 
 
 origin of, 95. 
 
 properties of, 62. 
 
 replaced by charcoal, 118. 
 
 source of carbonic acid, 117. 
 
 sources of, 117. 
 
 theory of its action, 119. 
 
 when soluble, 169. 
 
 unnecessary, 174. 
 
 Hyacinth, colored, 156. 
 Hyilrates, what, 48, 60. 
 Hydrocyanic acid, 110, 251. 
 
 decomposition of, 111, 251. 
 
 various substances from. 111. 
 Hydrogen, assimilation of, 120. 
 
 excess in wood accounted for, 
 121. 
 
 of decayed wood, 103. 
 
 of plants, source of, 122. 
 
 in oak and other woods, 82 
 
 influence of, upon plants, 79. 
 
 peroxide of, 254. 
 
 of sugar, 276. 
 Hydrogen and oxygen, union of, 41. 
 
 ICE, bubbles of gas in, 84. 
 Imponderables, 2. 
 Indifferent substances, 56. 
 Indifferent organic compounds, 375. 
 Infusorial vegetables in peat, &c., 215. 
 Ingenhouss, his experiments, 79. 
 Inorganic compounds, 262. 
 
 action of, 335. 
 
 in wliat they differ from or- 
 ganic, 263. 
 Inorganic constituents of plants, 147. 
 Insoluble geine, 59. 
 
 Interchange of crops, 206. 
 
 prmciples regulating the, 219. 
 Iodine, 168. 
 Iron, oxide of, attracts ammonia, 145. 
 
 pyrites in coal, 332. 
 Irrigation of meadows, effect of, 169, 
 
 214. 
 Isomorphism, 42. 
 Isomorphous crystals, 18. 
 Itch insect, 1G3. 
 
 JjiCKSON, Dr. C. T., his analysis of 
 horse dung, 224. 
 of peat, 231. 
 
 his views of the action of am- 
 monia, 411. 
 
 Juices of plants, azote in, 181. 
 effect of air upon, 293. 
 
 KINIC ACID, 155. 
 
 Lactic acid, production of, 277. 
 
 Lamp-black, 2d7. 
 Land, carbon in, 68, 
 
 oxygen from, 121. 
 La Place, law proposed by, 347. 
 Lava, soil from, 194. 
 Laws of chemical proportions, 32. 
 
 decomposition, 26. 
 Lead, salts of, compounds of with 
 organic matters, .345. 
 white, effects of, 345. 
 Leaves, absorb carbonic acid, 72. 
 
 aslies of contain alkalies, 198. 
 cessation of their functions, 
 
 108. 
 change of color from absorp- 
 tion of oxygen, 81. 
 consequence of the production 
 of their green principle, 218. 
 decompose carbonic acid, 186. 
 how regarded by physiolo- 
 gists, 87. 
 their office, 179. 
 power of absorbing nutriment, 
 
 how increased, 107. 
 quantity of carbon received 
 
 by, 75. 
 contain azotized matter, 234. 
 Lemonade, sulphuric acid, use of, 345. 
 Liebig, his application of the term 
 
 base, llo. 
 Life, notion of, 356. 
 Light, absence of, its effect, 79, 184. 
 chemical, effects of, 185. 
 cffi'ct of upon salts of silver, 
 345. 
 
MET 
 
 429 
 
 NIT 
 
 Light, influences decomposition of 
 
 carbonic acid, 83. 
 Lightning, its eflect on hay, 200. 
 Lime, phosphate of, in roots, 93. 
 
 in forest soil of U. S., 
 
 228. 
 Berzelius's opinion on its 
 mode of action, 410. 
 
 Dr. Dana's, 410. 
 
 Lindley, Professor, his remarlcs on 
 
 root secretions, 411. 
 Linen, changes in, 326. 
 Liquid, supposed decay in a, 104. 
 Liverwort, acids in, 149. 
 Lucern, phosphate of lime in, 204. 
 benefits of its culture, 217. 
 
 MacMRE-PRINCEP, his experi- 
 ments, 2<)8. 
 Magnesia, phosphate of in seeds, 93. 
 Malic acid, its composition, 123. 
 Malignant disease, 3(j8. 
 Manure, 206. 
 
 animal, yields ammonia, 136. 
 
 best for plants, 172. 
 
 carbonic acid from, 140. 
 
 components of should be 
 known, 188. 
 
 animal, 410. 
 
 use of in China, 415. 
 
 of the Chinese, 240. 
 
 effect of, 219. 
 
 for grain in Germany, 160. 
 
 nitrogen from, 140. 
 
 strong, use of, 161. 
 
 -water, its effect, 143. 
 
 from fish, «fcc , 414. 
 Manuring with lone, 229. 
 
 with clay, 144. 
 Maple juice, ammonia from, 134. 
 
 trees, sugar of, 180. 
 Mail, substance mistaken for, 215. 
 Mask, 308. 
 Matter, what, 1. 
 
 particles of, 262. 
 Meadow land, soil of, 159. 
 
 geine in, 59. 
 
 hay from, 159. 
 
 observation of a, its value, 94. 
 Meadows, irrigation of, 169. 
 Meconic acid, 155. 
 Medicine, action of remedies in, 234. 
 
 may act as poison, 360. 
 Melanic acid, 289. 
 Mcllitic acid, 104. 
 
 Metallic compounds required by 
 plants, 90. 
 
 Metallic oxides in fir-wood, 64. 
 Metalloids, 13. 
 
 Metals, power acquired by, 265. 
 Metamorphosis, 1 12, 252. 
 Miasm, defined, 373. 
 Miasms, 335. 
 
 most pernicious, 375. 
 Milk, use of knowledge of its com- 
 position, 91. 
 Minerals, attract ammonia, 145. 
 Mould, vegetable, 97. 
 
 conversion of woody 
 
 fibre into, 98, 105. 
 Moisture, its effect on wood, 99. 
 Molecules, different positions of, 258. 
 
 motion of, 347. 
 Morbid poisons, 352. 
 Mother-ley, 19. 
 Motion, its influence on chemical 
 
 forces, 257. 
 Mouldering of bodies, 325. 
 Muriatic acid, formed, 185. 
 Muscles in fish ponds, 164. 
 Muscle, animal, analysis of, 222. 
 Alust, fermentation of, 306. 
 
 J^TaPLES, soil of, 197. 
 JVarcotine, 155. 
 Kascent slate, 23. 
 Neutral salts, 35. 
 
 state, 14. 
 Nicotine, 311. 
 Night soil, 414. 
 NUe, soil of its vicinity, 214. 
 Nitrates in plants, 138. 
 Nitrate of silver, action of salt on, 
 
 345. 
 Nitric acid, 55. 
 
 action of on starch, 86. 
 
 from ammonia, 129, 301. 
 
 animals, 129. 
 
 formed, 299. 
 Nitric oxide, 55. 
 Nitrification, 95. 
 
 condition for, 302. 
 
 eremacausis not necessary to, 
 303. 
 Nitrogen, from animals, 129. 
 
 application of substances con- 
 taining it, 140. 
 
 assimilation of, 126. 
 
 binoxide of, 55. 
 
 chloride of, 254. 
 
 compounds of, 55. 
 
 peculiarity in them, 282. 
 
 deficient in excrements, why, 
 140. 
 
ORG 
 
 430 
 
 PHO 
 
 Mtrogen, described, 55. 
 
 difficulties of determininff, 
 301. ^ 
 
 eliminated, 113. 
 
 in excrements, 240. 
 
 from the atmosphere, 129. 
 
 in grass, 144. 
 
 in hay, 222 
 
 influence of upon plants, 7i). 
 
 in lichens, 146. 
 
 necessary to digestion, 182. 
 
 in plants, 56. 
 
 oxidation, of, 300. 
 
 of plants and seeds, how em- 
 ployed, 140. 
 
 its source, 127. 
 
 product of. greatest, how ef- 
 fected, 2i34. 
 
 production of, the object of 
 agriculture, 141. 
 
 protoxide of, 55. 
 
 replaced, 245. 
 
 transformation of bodies con- 
 taining, 269. 
 
 in rice, 139. 
 
 in solid excrements, 139. 
 
 in urine, 137. 
 
 in uric acid, 239. 
 Nutrition, conditions essential to, 89. 
 
 explained, 111. 
 
 inorganic substances required, 
 90. 
 
 superfluous, how employed, 
 107. 
 
 of young plants, 217. 
 
 0AK8, ashes of, 198. 
 
 excretions of, 78. 
 
 dwarf, 106. 
 Oak-iDOod affords hnmic acid, 63. 
 
 composition of, 99. 
 
 mouldered, analysis of, 100. 
 Odor of substances, 312. 
 
 of gaseous contagious matters, 
 374. 
 (Enanthic ether, 306. 
 Oil of brandy, 310. 
 
 of potatoes, 307. 
 
 of turpentine, composition of, 
 123. 
 
 volatile from potatoes, 115. 
 Oils, chemical nature of, 55. 
 Opium, acids, &c. in, 155, 
 Orcin, 288. 
 
 Organs of excretion, 113. 
 Organic acids, 55. 
 
 bases, 56. 
 
 Organic acids, chemical decompo- 
 sition of, 251. 
 
 chemistry, 53. 
 
 compounds, 123. 
 
 compared with inorganic, 262. 
 
 salts in plants, 150. 
 Organized bodies do not generate 
 
 substances, 109. 
 Oxalis, genus requiring potash, 93. 
 Oxamide, decomposition of, 354. 
 Oxide of carbon formed, 267. 
 Oxides, metallic in fir-wood, 04. 
 
 quantity of in soils, how in- 
 fluenced, 150. 
 
 reduction of, 255. 
 Oxygen acids, 35. 
 
 action on alcohol, 290. 
 
 absorbed by oils, 290. 
 
 absorption of at night, 83. 
 
 by leaves, 80. 
 
 respiration, 113. 
 
 plants, 79. 
 
 • wood, 81. 
 
 action upon woody fibre, 95. 
 
 its action in decomposition, 
 295. 
 
 bases, 35. 
 
 emitted by leaves, 72. 
 
 exhalation of influenced, 75. 
 
 given to air by land, 121. 
 
 extracted from air by mould,97. 
 
 in air, 70. 
 
 consumption of, 416. 
 
 in water, 84. 
 
 promotes decay, 172. 
 
 quantity consumed, 70. 
 
 replaced, 72. 
 
 returned to the air, 125. 
 
 separated during formation of 
 acids, 123. 
 
 with carbonic acid and 
 
 zinc, 125. 
 
 Painter's colic, 345. 
 
 Peat compost, 160, 413. 
 
 analysis of, 230. 
 
 ashes of, 230. 
 Pelargoniums, effect of chlorine 
 
 upon, 143. 
 Perennial plants, how nourished, 178. 
 Peroxide of liijdrogen, 2.54. 
 Petersen and Schodler, their analysis 
 
 of woods, 82. 
 Phosphate of lime in roots, 93. 
 
 in soils. Dr. Dana's opinion 
 of, 412. 
 
 magnesia in seeds, 93. 
 
PLA 
 
 431 
 
 PUS 
 
 Phosphates in seeds, 200. 
 Phosphoric acid in ashes of plants, 
 200. 
 source of, 200. 
 Physician, duty of in case of poison, 
 
 344. 
 Physiologists, their experiments not 
 satisfactory , 92. 
 neglect of chemistry b}', 86. 
 Physiology, object of experiments in, 
 
 08. 
 Pinus allies, absorbs oxygen, 80. 
 Pine apple, effect of cultivation on, 
 
 183. 
 Pine trees, ashes of, 1 51 . 
 
 of America, 199. 
 Pipe clay, ammonia in, 145. 
 Plants, absorb oxygen, 79. 
 
 ashes of, salts in, 150. 
 conditions necessary for their 
 
 life, 89. 
 contain carbon, 54. 
 decay of, a source of oxygen, 
 
 125. 
 decompose carbonic acid, 72. 
 development of, requisites 
 
 for, 56, 157, 179, 186. 
 effect of on rocks, 195. 
 elements of, 53. 
 emit acetic acid, 194. 
 exhalation of carbonic acid 
 
 from, 84. 
 of a former world, 117. 
 formation of their components, 
 
 124. 
 functions of, 77. 
 improve the air, 77. 
 indifferent substances of, 56. 
 influence of gases on, 79. 
 
 of shade, 79. 
 
 inorganic constituents of, 147. 
 life of connected vpith that of 
 animal, 73. 
 
 its products, 78. 
 
 milky-juiced in barren soil, 
 
 118. 
 organic acids in, 148. 
 
 salts in, 1.50. 
 
 perennial nourished, 178. 
 
 products of vary, 183. 
 
 size of proportioned to organs 
 
 of nourishment, 107. 
 succession of, its advantage, 
 
 216. 
 precautions in cultivat- 
 ing, 216. 
 vital process in, 125. 
 
 Plants, vital processes of, 212. 
 
 when injurious to each other, 
 2U5. 
 
 wild, obtain nitrogen from air, 
 141. 
 
 yield oxygen, 84. 
 Platinum, does not decompose nitric 
 
 acid, 253. 
 Ploughing, its use, 173. 
 Poisons, 355. 
 
 generated by disease, 352. 
 
 inorganic, 340. 
 
 peculiar class of, 346. 
 
 rendered inert by heat, 353. 
 Poisoning, superficial, 341. 
 
 from sausages, 350. 
 Pollen of pinus abies, contains phos- 
 phate of lime, 412. 
 Pompeii, air from, 70. 
 
 bones from, 203. 
 Poplars after pines, 199. 
 Potash, action of upon mould, 97. 
 
 in grapes, 153. 
 
 ley of, its effect on excre- 
 ments, 140. 
 
 presence of in plants account- 
 ed for, 193. 
 
 replaced by soda, 200. 
 
 required by plants, 93, 200. 
 
 quantity in soils, 192. 
 
 saliculite of, 289. 
 
 sihcate of, in soils, 93. 
 
 sources of, 162. 
 Potassium, its affinity for oxygen, 
 
 291. 
 Potatoes, analysis of, 154. 
 
 oil of, 116,307. 
 
 effect of as food, 183. 
 
 germination of, 176. 
 
 produce of increased, 177. 
 Potato brandy, 308. 
 
 starch, action of nitric acid 
 on, 86. 
 Precipitation, 21. 
 Predisposing affinity, 24. 
 Preservation of animal food, 294 
 Priestley and others on assimilation 
 
 of carbon, 85. 
 Processes, chemical, in nature, 53. 
 Products of transformations, 109. 
 Properties of bodies, 2. 
 
 chemical, 8. 
 Projjortions, chemical, 121. 
 
 laws of, 32. 
 
 theory of, 36. 
 Prussic arid, 110. 
 Pus, globules in, 362. 
 
SAL 
 
 432 
 
 SOI 
 
 Purgative effect of salts, explained, 
 
 33'j. 
 rutrefaction, 94, 259. 
 of animals, 219. 
 communicated, 3.52. 
 induced, 293. 
 removes oxygen, 72. 
 source of ammonia, 129. 
 
 of carbonic acid, 140. 
 
 Putrefying sausages, death from, 
 351. 
 their mode of action, 359. 
 substances, effect of upon 
 wounds, 349. 
 
 may act as medicines, 
 
 360. 
 
 alkaline, 361. 
 
 acid, 362. 
 
 Pyrogallic acid, experiments in, 288. 
 
 qumiNE, 232. 
 
 Rain-water, alkali extracted by, 
 
 194. 
 Reduction of oxides, 255. 
 Heeds and canes require silica, 200. 
 Removal of branches, effect of, 174. 
 Reservoirs of dung, 237. 
 Rhine, soils in its vicinity, 214. 
 
 wines, 307. 
 Riessling grapes, 308. 
 Ripening of fruit, 175. 
 Rockii, effect of plants on, 195. 
 Root secretions, 411. 
 Roots, absorb, 147. 
 
 emit extractive matter, 208. 
 
 their office, 167. 
 
 SACHULMIN, 263. 
 Saliculite of potash, 289. 
 Saline plants, 163. 
 Salsola kali, 154. 
 SaZ<, what, 110. 
 
 upon leaves, 165. 
 
 volatilization of, 166. 
 Salts, acid, 48. 
 
 absorption of, 157. 
 
 basic, 47. 
 
 chlorine, 50. 
 
 common, its effect on poisons, 
 344. 
 
 of copper, 246. 
 
 double, 47. 
 
 effect of, on the organism, 
 337. 
 
 effect of, on flesh, 338. 
 
 on the stomach, 339. 
 
 Salts, fluorine, 50. 
 
 halhydrate, 48. 
 
 haloid, 51. 
 
 neutral, 49. 
 
 organic in plants, 1.50. 
 
 in the blood, 337. 
 
 oxygen, 46. 
 
 sulphur, 50. 
 
 theory of their constilution, 
 46. 
 
 passage of, through the lungs, 
 337. 
 Salt-works, loss in, 166. 
 Saltwort, 93. 
 Sand, plants in, 118. 
 Sandy soil, decay of wood in, 102. 
 Sap, ascending, dissolves sugar, 181. 
 Saturating capacity of acids, 47. 
 Sausages, poisonous, 350. 
 Saussure, his experiments on air, 71. 
 
 on growth of plants, 203. 
 Saiodust, changes in, 326. 
 Scales of thermometers, correspond- 
 ing, 419. 
 Schilbler, his observations on rain, 
 
 132. 
 Sea-water, analysis of, 166. 
 
 contains carbon, 74. 
 
 requires iodine, 168. 
 Seeds, substance of, its use, 105. 
 
 of grapes, constituents of, 148. 
 
 follow man, 162. 
 Shade, its effect, 75. 
 Silica, in grasses, 158. 
 
 in reeds and canes, 200. 
 
 in soils and springs, 215. 
 Silicate of potash, in plants, 93. 
 
 in wheat, 198. 
 Siliceous sinter, 215. 
 Silicic acid, 21.5. 
 
 Silver, carbonate of, action of organ- 
 ic acids on, 256. 
 
 salts of, poisonous effect of, 
 244. 
 Sinapis alba, 376. 
 Size of plants proportional to organs 
 
 of nourishment, 107. 
 Smell, what, 374. 
 Snow-water, ammonia in, 132. 
 Soda, may replace potash, 200. 
 Soils, advantage of loosening, 106, 
 172 
 
 best for meadow land, 159. 
 
 carbon restored to, 116. 
 
 chemical nature of, its influ- 
 ence, 213. 
 
 constituents of, 190. 
 
SUG 
 
 433 
 
 TOB 
 
 Soi75, exhaustion of, 196. 
 
 ferruginous, improved, 144, 
 
 fertile, of Vesuvius, J93. 
 
 fertility of, influence, 141. 
 
 from lava, 194. 
 
 heavy, retain water, 102. 
 
 imbibe ammonia, 141. 
 
 improved by crops, 206. 
 
 impoverished by, 206. 
 
 nature of its influence, 150. 
 
 necessary to plants, 56. 
 
 of South America, manure for, 
 244. 
 
 varieties of, 191. 
 
 of Virginia, 196. 
 Solution, 7. 
 
 saturated, 16. 
 Specific weights, 3. 
 Spontaneous combustion, 287. 
 Springs, carbonic acid from, 126, 331. 
 
 containing ammonia, 133. 
 
 of Iceland, and the Azores, 
 215. 
 
 quantity of geine in, 59. 
 Stagnant water, effect of, 172. 
 Stalactites in caverns, 170. 
 Starch, accumulation of, in plants, 
 177 
 
 composition of, 123. 
 
 contains amylum, 86. 
 
 development of plants influ- 
 enced by, 177. 
 
 effect of, on malt, 114. 
 
 product of the life of plants, 78. 
 
 products from, 176. 
 
 in trees, 175. 
 
 in willows, chanffes in the, 
 176. ^ 
 
 Staunton, Sir G.,on Chinese manure, 
 
 241. 
 Steam, decomposed, 266. 
 Stimulants, to plants, 143. 
 St. Michael, island of, 215. 
 Stomach, calves', experiment with, 
 114. 
 
 its power, 349. 
 Straw, analysis of, 68. 
 
 carbon in, 68. 
 Struve, experiments of, 195. 
 Substitution of Oases, 149. 
 Succinic a-id, 104. 
 Sugar, action of alkalies upon, 265. 
 
 acids upon, 264. 
 
 alcohol from, 45. 
 
 amorphous, 258. 
 
 analysis of. 275. 
 
 carbon in, 67. 
 
 37 
 
 Sugar, composition of, 123. 
 
 crystallized, 25S. 
 
 development of plants, influ- 
 ence on, 177. 
 
 fermentation of, 275. 
 
 formula for, 263. 
 
 of maple trees, 180. « 
 
 hydrogen of, 276. 
 
 maximum of, in beet roots, 184. 
 
 metamorphosis of, 276. 
 
 organic compounds calculated 
 from, 264. 
 
 product of the life of plants, 78. 
 
 transt'ormalion of, 268. 
 
 when produced, 108. 
 Sugar-cane, disappearance of its su- 
 gar, 177. 
 Sulphur, acidified, 93. 
 
 cry!*taliized, 258. 
 
 salts, 50. 
 Svlphuret, what, 13. 
 Sulpuretted hydrogen, 112, 
 Suh)huric acid, saturating power of, 
 47. 
 
 action of on soils, 247. 
 
 lemonade, use of, 345. 
 Sulphurous acid arrests decay, 102. 
 Sicamp muck, 231. 
 Sioine, urine of, 245. 
 Synapsis, 376. 
 
 TJiBASHEER,A\\. 
 
 Table of Hessian & English weights, 
 
 416. 
 Tannic acid, 123. 
 Tartaric acid, 123. 
 
 converted into sugar, 124. 
 
 in wines, 307. 
 Tcltoioa turnip, 107, 184. 
 Temperature, 9. 
 
 its influence, 23. 
 Tension of bodies, 6. 
 Thinard, his experiments on yeast, 
 
 279. 
 Theory, atomic, 38. 
 
 of chemical proportions, 36. 
 
 of salts, 46. 
 Thermometer, 10. 
 Thermometers, corresponding scales 
 
 of, 419. 
 Thomson, his opinion respecting hu- 
 mus, 58. 
 Tin, action on nitric acid, 253. 
 Toiflcco, juice contains ammonia, 135 
 
 leaves of, 31 1. 
 
 nitric acid in, 138. 
 
 in Virginia, 196. 
 
VEG 
 
 434 
 
 WOO 
 
 Tobacco, and wheat, 205. 
 Transformriiion by heat, 267. 
 
 chemical, 109, 149. 
 
 differ from decomposi- 
 tions, 112. 
 
 of acetic acid, 267. 
 
 of arragonite, 258. 
 
 of carbonic acid, 186. 
 
 of nieconic acid, 267. 
 
 not affected by the vital prin- 
 ciple, 114. 
 
 explained, 114. 
 
 of bodies containing nitrogen, 
 
 results of, 116. 
 
 peculiar, in plants, 108. 
 
 of wood, 2G8. 
 
 of cyanic acid, 271. 
 
 of cyanogen, 272. 
 
 of gluten, 304. 
 Transjdantalion, effect of, 174. 
 Trees, diseases of. 181. 
 
 require alkalies, 198. 
 Turnip, small, 107. 
 Turpentine, oil of, 123. 
 
 Vlmin, 57 
 
 Union of gases, 39. 
 
 Urea, 127. 
 
 converted into carbonate of 
 ammonia, 138. 
 
 in urine, 236. 
 Uric acid, contains ammonia, 239. 
 
 transformations of, 229. 
 Urinary calculi, treatment of, 114. 
 
 organs eliminate nitrogen, 113 
 Urine, contains nitrogen, 137. 
 
 its use as manure, 137, 235. 
 
 of men, &c., 138. 
 
 of horses, 143. 
 
 analysis of, 144. 
 
 human, analysis of, 236. 
 
 of cows, 222. 
 
 its use in Flanders, 241. 
 
 of swine, 245. 
 
 VACCINATION, its effect, 372. 
 
 Vapors, what, G, 12. 
 
 Vegetables, contain hydrogen, 122. 
 
 nutrition of, chemical proces- 
 ses in the, 53 
 
 supply carbonic acid to water, 
 85. 
 
 vital activity of, 190. 
 Vegetable albumen, 137. 
 
 mould, 97. 
 Vegetable inices, fermentation of, 276. 
 
 Vesuvius, fertile soil of, 193. 
 Vines, effect of manure on, 161. 
 
 juice of, yields ammonia, 135. 
 Vinous fermentation, 303. 
 Virginia, early products of its soil, 
 
 196. 
 Virus of smallpox, »&c., 352. 
 
 vaccine, 302. 
 Vitality, what, 90. 
 Vital principle, 113, 357. 
 
 value of the term, 115. 
 
 how balanced in the blood, 
 372. 
 Vital process in plants, 125, 
 Vital processes of plants, 212. 
 Volume, 2. 
 
 connexion of, with atomic 
 weight, 41. 
 Volumes, theory of, 41. 
 
 Water, carbonic acid of, absorbed, 
 85. 
 
 composition of, 123. 
 
 dissolves mould, 97. 
 
 of crystallization, 20. 
 
 effect of, 284. 
 
 from ammonia, 302. 
 
 plants, their action, 85. 
 
 rain, carbon conveyed by, 66. 
 
 contains ammonia, 146. 
 
 required by plants, 56, 
 
 120. 
 
 required by gypsum, 144. 
 
 salt, analysis of, 166. 
 WaveUitc, 201. 
 Wax in plants, its use, 118. 
 Weight, atomic, 39. 
 
 connexion of, with volume, 
 41. 
 
 specific, 3. 
 
 of gases, 42. 
 
 Wheat, analysis of, 199. 
 
 ashes of, 203. 
 
 exhausts, 197. 
 
 gluten of, 136. 
 
 and tobacco, 205. 
 
 why it does not thrive, 198. 
 
 in Virginia, 196. 
 Willows, growth of, 176. 
 Wine, effect of gluten upon, 313. 
 
 fermentation of, 306. 
 
 properties of, 313. 
 
 substances in, 306. 
 
 taste and smell of, 307. 
 
 varieties of, 307. 
 Winter, early, its effect, 161. 
 Wood, decomposition of, 283. 
 
woo 
 
 435 
 
 ZIN 
 
 Wood charcoal, may replace humus, 
 118. 
 
 decayed, combustion of, 103. 
 
 absorbs ammonia, 14G. 
 
 absorbs oxygen, 81. 
 
 analysis of, 82. 
 
 carbon in, 67. 
 
 conversion of, into humus, 95. 
 
 decay of, 101. 
 
 requires air, 96. 
 
 in sandy soil, 102. 
 
 decomposition of, 250, 283. 
 
 effect of moisture and air, 99. 
 
 elements of, 101. 
 
 formation of, 181. 
 
 oak, mouldering, 82. 
 
 ripening of, 176 
 
 source of its carbon, 68. 
 
 transformation of, 268. 
 Wood-coal, 325. 
 
 how produced, 327. 
 
 analysis of, 328. 
 Wood-cutters, their privilege, 160. 
 Woody fibre, carbon in, 77. 
 
 changes in, 325. 
 
 composition of, 123. 
 
 Woody fibre, decomposition of, 98. 
 
 difference between it and 
 
 wood, 82. 
 formation of, 77. 
 moist evolves carbonic acid, 
 
 289. 
 mould from, 98. 
 phenomena attending its de- 
 cay, 95. 
 Wormwood, effect of its culture, 
 
 161. 
 Wort, fermentation of, 305. 
 Wounds, effect of putrefying sub- 
 stances on, 349. 
 
 VeaST, 277. 
 
 destroyed, 306. 
 experiments on, 279. 
 formed, 306. 
 its mode of action, 279. 
 its action arrested , 309. 
 its production, 348. 
 
 ZINC, decomposition of water with, 
 125. 
 
ERRATA. 
 
 Page 53, line 3, after Agriculture insert and Physiology 
 
 " 58, " 32, " alkalies " and with lime 
 
 " 69, " 24, for Dr. Dana has given read Prof. Hitchcock has given. 
 
 The refeieiic in the note on page 407, should be to Dr. Dana's Table, page 402. 
 
 av'08 
 
 -s??::^