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CHEMISTRY

IN ITS APPLICATION TO

AGRICULTUEE AND PHYSIOLOGY.

BY I

JUSTUS LIEBIG, M.D., Ph.D., F.R.S., M.R.I.A.,

PROFESSOR OF CHEMISTRY IN THE UNIVERSITT OF 6IESSEN,
ETC., ETC., ETC.

' /

EDITED FROM THE MANUSCRIPT OF THE AUTHOR

By LYON PLAYFAIR, Ph.D.

VERY NUMEROUS ADDITIONS, AND A NEW CHAPTER ON SOILS.

THIRD AMERICAN, FROM THE SECOND ENGLISH EDITION,

WITH
NOTES, AND APPENDIX,

JOHN W. WEBSTER, M.D.,

ERVINO PROFESSOR OF CHEMISTRY IN HARVARD UNIVERSITY.

iFOB*' CAMBRIDGE:
PUBLISHED BY JOHN OWEN.

BOSTON, JAMES MUNROB AND COMPANY, AND CHARLES C. LITTLE AND JAMES BROWN ;

NEW YORK, WILEY AND PUTNAM, AND GEOROK C. THORBURN ; PHILADELPHIA,

THOMAS, COWPERTHWAIT, AND COMPANY, AND CAREY AND HART ;

BALTIMORE, CUSHINO AND BROTHER.

1842.

'«»

V)
V

■■')

Entered according to Act of Congress, in the year 1842, by

John Owen,

in the Clerk's office erf* the District Court of the District of Massachusetts.

CAMBRIDGE;

STEREOTYPED AND PRINTED BY

METCALF, KEITH, AND NICHOLS,

PRINTERS TO THE UNIVERSITY.

CONTENTS.

Preface to the Third American Edition

Dedication

Preface to the Second English Edition

Object of the Work

PAGB

XIII

XVII

PART FIRST.

ON THE CHEMICAL PROCESSES IN THE NUTRITION OF VEGETABLES.

dRAPTEB PAGE

I. — On the Constituent Elements of Plants . . 24

n. — On the Assimilation of Carbon . . .30

ni. — On the Origin and Action of Humus . . 63

IV. — On the Assimilation of Hydrogen . . .80

V. — On the Origin and Assimilation of Nitrogen . 65

VI. — On the Inorganic Constituents of Plants , . 105

Vn. — The Art of Culture .... 126

Vin. — On the Alternation (Rotation) of Crops . .161

IX. — On Manure ..... 174

Supplementary Chapter. —On the Chemical Constitu-
ents of Soils . . . . . 208

Appendix to Part I. ..... 249

Action of Charcoal on Vegetation , • 249

Mode of Manuring Vines .... 253

Root Secretions . . , , • ^56

Peat Compost . . • • . 258

Source of the Carbon of Plants . . . 260

Source of the Hydrogen of Plants . . . 263

Dependence of the Nutritive Qualities of Plants on

Nitrogen . . . . .265

iv CONTENTS.

Difference in the Power of Plants to decompose

Ammonia ..... 266

Practical Inferences . . • . 268

Use of Phosphate of Soda .... 286

Daniell's Artificial Manure . • • 287

PART SECOND.

ON THE CHEMICAL PROCESSES OF FERMENTATION, DECAY, AND

PUTREFACTION.

CHAPTER PAGE

I. — Chemical Transformations . . . 289
n. — On the Causes which effect Fermentation, Decay,

and Putrefaction . . . . . 292
ni. — Fermentation and Putrefaction . . . 300
IV. — On the Transformation of Bodies which do not con-
tain Nitrogen as a constituent, and of those in
which it is present .... 305
V. — Fermentation of Sugar . , . .313
VI. — Eremacausis, or Decay . . . 322
Vn. — Eremacausis of Bodies destitute of Nitrogen : For-
mation of Acetic Acid . . . 329
VTEI. — Eremacausis of Substances containing Nitrogen :

Nitrification .... 334

IX. — On Vinous Fermentation : Wine and Beer . 338

X. -—On the Decay of Woody Fibre . . 357

XI. — On Vegetable Mould . . . .363

Xn. — On the Mouldering of Bodies : Paper, Brown Coal,

and Mineral Coal . . . . 365

Xni. — On Poisons, Contagions, and Miasms . 373
Appendix to Part II. . . , . .415

Tables, — Showing the Proportion between the Hessian

and English Standard of Weights and Measures 416
Index . . , . . . 419

PREFACE

TO THE

THIRD AMERICAN EDITION.

This volume constitutes the First Part of Professor
Liebig's Report on Organic Chemistry, drawn up by
request of the British Association for the Advancement
of Science.*

The interest excited in Great Britain on the appear-
ance of this work from one of the most eminent
chemists in Europe, and the high encomiums be-
stowed upon it by individuals, and leEirned bodies,
together with the various notices of it which have
been published by Professor Lindley, Professor Dau-
beny, and others, all concurring in the opinion, that
the information it contains is of great amount, and
that from its publication might be dated a new era

* The Second Part has just been published, viz., "Animal Chemistry,
or Organic Chemistry in its Application to Physiology and Pathology.
By Justus Liebig, M. D., F. R. S., M. R. 1. A., Professor of Chemistry
in the University of Giessen, &c., &c., &c. Edited from the Author's
Manuscript, by William Gregory, M. D., F. R. S., M. R. I. A.,
Professor of Medicine and Chemistry in the University and King's
College, Aberdeen. With Additions, Notes, and Corrections, by Dr.
Gregory, and others by John W. Webster, M. D., Erving Professor of
Chemistry in Hirvard University."

Vi PREFACE TO THE

in the art of agriculture, induced the editor to suggest
its republication in this country.

Contrary to the expectations of the author, and of
the editor, the work has received the attention not
only of scientific readers, for whom it was written,
but of practical agriculturists, and4those who could
hardly have been supposed prepared to derive much
advantage from its perusal. The influence of the
opinions of Professor Liebig, and the impetus the
appearance of the present work gave to the advance-
ment of scientific agriculture, have been evinced by the
many publications which have since appeared, both in
Great Britain and in this country.

What is valuable in too many of these publications,
diluted as it has been and mingled with erroneous
statements, was for the first time given in a consistent
shape in the present work.

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 indeed been
suspected, that very small quantities of ammonia in
the atmosphere might furnish the nitrogen, ammonia
being a compound of nitrogen and hydrogen. It
may be objected, that the quantity of ammonia pres-
ent in the atmosphere, and in rain and snow water, is

THIRD AMERICAN EDITION. vii

exceedingly small, quite insufficient for the supply of
all the nitrogen that enters into the vegetable struc-
ture. To this it has been replied by Professor Lind-
ley, in an elaborate review of Liebig's work, that
^^ the quantity of ammonia given off from thousands
of millions of putrefying animals must furnish an
abundant, an everlasting source of that principle."

Important as ammonia, or its nitrogen, is conceived
to be to plants, it will be seen that Liebig considers
carbon not less so.

Since the appearance of the former editions of this
work, the opinions of American chemists in regard to
humus, have become so generally diffused, in the
various Agricultural Reports, that it has not been
deemed necessary to retain, in this edition, much that
was appended to the second.

Professor Lindley, in speaking of humus, recogni-
ses it as " the dark substance which remains when
manure is thoroughly rotted, and which colors the
soil black, and without going into any technical ex-
amination of this product, we may state," he con-
tinues, "that it is a substance formed by the decay of
plants, and very rich in carbon." He then quotes the
expression of Liebig, that this substance, in the form
in which it exists in the soil, does not yield? nourish-
ment to plants, and expresses surprise, that the author ^
should have thought it worth his while to raise such
a phantom for the mere pleasure of subduing it. for
no one in Great Britain now entertains the opinion,
that humus is in itself the food of plants. ^^ Every

Vlll ^ PREFACE TO THE

Student of botany is taught, that humus becomes the
food of plants only by combining with the oxygen of "
the atmosphere and forming carbonic acid gas, and
hence the great importance of preserving the roots of
plants in communication with the atmosphere, which
is the great source of oxygen." .

In noticing the effect of alkalies, Professor Lindley
remarks, that it will lead to the explanation of many
things that were inexplicable before. " When it is
said, that a plant becomes tired of a soil, and we find
that manuring fails to invigorate it, the destruction of
alkalies in the soil, and the want of a sufficient supply
of those bases in the manure, seem to offer a solution
of the enigma. And in like manner the gradual de-
cay of trees in public squares and promenades, where
the soil is incessantly robbed of alkaline matter for
the sake of neatness, may probably be ascribed to the
same cause. So 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 compo-
nent parts of the soil, and in proportion to the vigor
of their growth, that of the crop must decrease ; for
what one receives the others are deprived of."

"It is impossible for any one acquainted with gar-
^ dening not to perceive the immense importance 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 car-
ried backwards, instead of being advanced ; and that

THIRD AMERICAN EDITION. ix

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.''

Of the importance of alkalies and salts to plants,
there would seem to be no doubt, and although the
credit of this discovery is in England given to Liebig,
it was not new in the United States, having been an-
nounced by Dr. S. L. Dana of Lowell, and urged
upon the attention of cultivators in the various Re-
ports on the Agriculture of Massachusetts, several
years ago.

As in this work many chemical and technical terms
are necessarily made use of, and it may come into the
hands of some persons who are not familiar with them,
explanatory notes have been added which it is hoped
may render the text more intelligible. The notes
that are contained in the original work are distin-
guished by initials or abbreviations.

A valuable addition has been made in the extracts
from the lectures delivered after the appearance of
Liebig's work by Professor Daubeny at Oxford, on
Agriculture and Rural Economy. The greater part
of the third lecture is given in the Appendix, being
a summary of the practical applications of the prin-
ciples developed and discussed in the body of this
work.

It has been highly gratifying to the editor, to learn
from the gentleman under whose supervision the work
first appeared in England, that its republication, and

X PREFACE TO THE

the manner in which it has been edited in this coun-
try, have met with his entire approbation. To Dr.
Playfair the editor is also indebted for some valuable
suggestions which were followed in preparing the
second edition, and for which he would express his
thanks.

A copious index, in which the original work is de-
ficient, has been added, and numerous errors of the
English press have been corrected.

The estimation in which Professor Liebig's work
was viewed by the ''British Association for the Ad-
vancement 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 origi-
nating in their recommendation."

On the 30th of November, 1840, at the anniversary
meeting of the Royal Society, one of the Copley
medals was awarded to the author ; and on this occa-
sion, in his absence, the President, 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 Liefeig. My principal
difficulty, in the present exercise of this the most
agreeable part of my official duty, is to know wheth-
er to consider M. Liebig'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

THIRD AMERICAN EDITION. XI

world, enhanced by the practical and useful ends to
which he has turned his discoveries."

To Dr. S. L. Dana, of Lowell, the editor would ac-
knowledge his obligations for valuable suggestions
and the communication of some important additions,
and also to Mr. Charles E.Buckingham, of the Medical
School of this University, for his valuable assistance
in correcting the proofs.

J. W. W.

Cambridge, September, 1842.

THE BRITISH ASSOCIATION

FOR THE

ADVANCEMENT OF SCIENCE.

One of the most remarkable features of modern
times is the combination of large numbers of indi-
viduals representing the whole intelligence of nations,
for the express purpose of advancing science by their
united efforts, of learning its progress, and of commu-
nicating new discoveries. The formation of such as-
sociations is, in itself, an evidence that they were
needed.

It is not every one who is called by his situation
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 scientific institutions is an ac-
knowledgment of these benefits, and this acknowl-
edgment, proceeding 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, by the truths

THE BRITISH ASSOCIATION

FOR THE

ADVANCEMENT OF SCIENCE.

It is not every one who is called by his situation
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 scientific institutions is an ac-
knowledgment of these benefits, and this acknowl-
edgment, proceeding 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, by the truths.

XIV DEDICATION.

which assiduous and active inquirers have discovered
and rendered capable of practical application. But it
is not the mere practical utility of these truths which
is of importance. Their influence upon mental cul-
ture is most beneficial ; and the new views acquired
by the knowledge of them enable the mind to recog-
nise, in the phenomena of nature, proofs of an Infinite
Wisdom, for the unfathomable profundity of which,
language has no expression.

At one of the meetings of the chemical section of
the " British Association for the Advancement of
Science," the honorable task of preparing a Report
upon the state of Organic Chemistry was imposed
upon me. In the present work I present to the As-
sociation a part of this Report.

I have endeavored to develop, in a manner corre-
spondent to the present state of science, the fundamen-
tal principles of Chemistry in general, and the laws
of Organic Chemistry in particular, in their applica-
tions to Agriculture and Physiology ; to the causes of
fermentation, decay, and putrefaction ; to the vinous
and acetous fermentations, and to nitrification. The
conversion of woody fibre into wood and mineral 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.

I shall be happy if I succeed in attracting the at-
tention of men of science to subjects which so well
merit to engage their talents and energies. Perfect
Agriculture is the true foundation of all trade and in-

DEDICATION. XV

dustry, — it is the foundation of the riches of states.
But a rational 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 difierent substances
from which plants derive. their nourishment.

The chemical forces play a part in all the processes
of the living animal organism ; and a number of trans-
formations and changes in the living body are exclu-
sively dependent on their influence. The diseases in-
cident to the period of growth of man, contagion and
contagious matters, have their analogues in many
chemical processes. The investigation of the chemi-
cal connexion subsisting between those actions pro-
ceeding in the living body, and the transformations
presented by chemical compounds, has also been a
subject of my inquiries. A perfect 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 at-
tention to the subject.

Since the time of the immortal author of the " Ag-
ricultural Chemistry," no chemist has occupied him-
self in studying the applications of chemical principles
to the growth of vegetables, and to organic processes.

XVI DEDICATION.

I have endeavored 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 object of
our research.

In presenting this Report to the British Association
I feel myself bound to convey my sincere thanks to
Dr. Lyon Playfair, of St. Andrew's, for the active as-
sistance 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
succeed in being as useful, by his profound and well-
grounded knowledge of chemistry, as his talents

promise.

JUSTUS LIEBIG.

Giessen, September 1, 1840.

EDITOR'S PREFACE

THE SECOND ENGLISH EDITION.

The former edition of this work was prepared in
the form of a Report on the present state of Organic
Chemistry. The state of a science such as this
could not be exhibited by a systematic treatise on
organic compounds, but by showing, that the science
was so far advanced as to be useful in its practical
applications.

The work was written by a Chemist, and address-
ed to Chemists. The author did not flatter himself,
that his opinions would be so eagerly embraced by
agriculturists, as circumstances have shown to be the
case. Hence his language and style were less adapt-
ed for them than for those who are conversant with
the abstract details of chemical science. But the
eager reception of the work by agriculturists has
shown, that they possess an ardent desire to profit
by the aids ofiered to them by Chemistry. It, there-
fore, became necessary to adapt the work for those
who have not had an opportunity of making that
science a peculiar object of study.

XVm EDITOR'S PREFACE TO THE

The Editor has endeavored to effect this change.
In doing so, it was necessary to retain the original
character of the work ; hence those alterations only-
have been made which are calculated to render the
work more generally useful. It must be remember-
ed, that the object of the author was not to write a
^^ System of Agricultural Chemistry," but to furnish
a *^ Treatise on the Chemistry of Agriculture." It
is to be hoped, that those who are acquainted with
the general doctrines of Chemistry will find no diffi-
culty in comprehending any of the principles here
developed.

The author has enriched the present edition with
many valuable additions ; allusion may be particular-
ly made to the practical illustration of his principles
furnished in the supplementary Chapter on Soils.
The analyses of soils contained in that chapter will
serve to point out the culpable negligence exhibited
in the examination of English soils. Even in the
analyses of professional chemists, published in detail,
and with every affectation of accuracy, the estima-
tion of the most important ingredients is neglected.
How rarely do we find phosphoric acid amongst the
products of their analyses ? potash and soda would
appear to be absent from all soils in the British ter-
ritories ! Yet these are invariable constituents of
fertile soils, and are conditions indispensable to their
fertility.

It is necessary to state, that all additions and alter-
ations, with a few unimportant exceptions, have been

SECOND ENGLISH EDETION. xix

submitted to the revision of the author. The Index
at the end of the volume has been principally com-
piled from one furnished by Professor Webster, of
Harvard University, in his American edition of this
work. The editor gladly avails himself of this op-
portunity to thank this gentleman for the care and
attention which he has displayed in superintending
its republication. '

Primrose, November 22, 1841.

ORGANIC CHEIISTEY

IN ITS APPLICATION TO

VEGETABLE PHYSIOLOGY AND AGRICULTURE.

The object of Chemistry is to examine into the
composition of the numerous modifications of mat-
ter, which occur in the organic and inorganic king-
doms of nature, and to investigate the laws by
which the combination and decomposition of their
parts is effected.

Although material substances assume a vast vari-
ety of forms, yet chemists have not been able to de-
tect more than fifty-five bodies which are simple, or
contain only one kind of matter, and from these all
other substances are produced. They are considered
simple only because it has not been proved that they
consist of two or more parts. The greater number
of the elements occur in the inorganic kingdom.
Four only are found in organic matter.

But it is evident that this limit to their number
must render it more difficult to ascertain the precise
circumstances, under which their union is effected,
and the laws which regulate their combinations.
Hence chemists have only lately turned their atten-
tion to the study of the nature of bodies generated
by organized beings. A few years have, however,
sufficed to throw much light upon this interesting
department of science, and numerous facts have been
discovered which cannot fail to be of importance in
their practical applications.

22 CONDITIONS ESSENTIAL TO NUTRITION.

The peculiar object of organic chemistry * is to
discover the chemical conditions essential to the life
and perfect development of animals and vegetables,
and generally to investigate all those processes of
organic nature vsrhich are due to the operation of
chemical laws. Now, the continued existence of all
living beings is dependent on the reception by them
of certain substances, which are applied to the nu-
trition of their frame. An inquiry, therefore, into
the conditions on which the life and growth of living
beings depend, involves the study of those substan-
ces which serve them as nutriment, as well as the
investigation of the sources whence these substances
are derived, and the changes which they undergo in
the process of assimilation.

A beautiful connexion subsists between the or-
ganic and inorganic kingdoms of nature. Inorganic
matter affords food to plants, and they, on the other
hand, yield the means of subsistence to animals.
The conditions necessary for animal and vegetable
nutrition are essentially different. An animal re-
quires for its development, and for the sustenance
of its vital functions, a certain class of substances
which can only be generated by organic beings pos-
sessed of life. Although many animals are entirely
carnivorous, yet their primary nutriment must be
derived from plants ; for the animals upon which
they subsist receive their nourishment from vegeta-
ble matter. But plants find new nutritive material
only in inorganic substances. Hence one great end
of vegetable life is to generate matter adapted for
the nutrition of animals out of inorganic substances,
which are not fitted for this purpose. Now the pur-

* 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 chemi-
cal 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.

SUBJECT OF THE WORK. 23

port of this work is, to elucidate the chemical pro-
cesses engaged in the nutrition of vegetables.

The first part of it will be devoted to the exam-
ination of the matters which supply the nutriment
of plants, and of the changes which these matters
undergo in the living organism. The chemical com-
pounds which afford to plants their principal con-
stituents, viz. carbon and nitrogen, will here 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.

The second part of the work will treat of the
chemical processes which effect the complete de-
struction of plants and animals after death, such as
the peculiar modes of decomposition, usually de-
scribed 2iS fermentation, putrefaction, and decay ; and
in this part the changes w^hich organic substances
undergo in their conversion into inorganic com-
pounds, as well as the causes which determine these
changes, will become matter of inquiry.

iimr

PART I.

OF THE CHEMICAL PROCESSES IN THE NUTRITION

OF VEGETABLES.

CHAPTER L

OF THE CONSTITUENT ELEMENTS OF PLANTS.

The ultimate constituents of plants are those which
form organic matter in general, namely, Carbon, Hy-
drogen, Nitrogen, and Oxygen. These elements are
always present in plants, and produce by their union
the various proximate principles of which they con-
sist. It is, therefore, necessary, to be acquainted
with their individual characters, for it is only by a
correct appreciation of these that we are enabled to
explain the functions which they perform in the veg-
etable organization.

Carbon is an elementary substance, endowed with
a considerable range of affinity. With oxygen it
unites in two proportions, forming the gaseous com-
pounds known under the names of carbonic acid and
carbonic oxide. The former of these is emitted in
immense quantities from many volcanoes and mineral
springs, and is a product of the combustion and de-
cay of organic matter. It is subject to be decom-
posed by various agencies, and its elements then ar-
range themselves into new combinations. Carbon is
familiarly known as charcoal^ but in this state it is
mixed with several earthy bodies ; in a state of ab-
solute purity it constitutes the diamond.*

* Wood charcoal contains about l-50th of its weight of alkaline and
earthy salts, which constitute the ashes when it is burned.

OF THE CONSTITUENT ELEMENTS OF PLANTS. 25

Hydrogen (^hiflammable Air) is a very important
constituent of vegetable matter. It possesses a
special affinity for oxygen, with which it unites and
forms water. The whole of the phenomena of decay
depend upon the exercise of this affinity, and many
of the processes engaged in the nutrition of plants
originate in the attempt to gratify it. Hydrogen,
when in the state of a gas, is very combustible, and
the lightest body known ; but it is never found in
nature in an isolated condition. Water is the most
common combination in which it is presented ; and
it may be removed by various processes from the
oxygen, with which it is united in this body.

Nitrogen * is quite opposed in its chemical char-
acters to the two bodies now described. Its princi-
pal characteristic is an indifference to all other sub-
stances, and an apparent reluctance to enter into
combination with them. When forced by peculiar
circumstances to do so, it seems to remain in the
combination by a vis inertice ; and very slight forces
effect the disunion of these feeble compounds.

Yet nitrogen is an invariable constituent of plants,
and during their life is subject to the control of the
vital powers. But when the mysterious principle of

* This gas was discovered in 1772, and is called also azote or azotic
ffaSj from the Greek, expressive of its being incapable of supporting
life. The name Nitrogen 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 compos-
ed of four fifths nitrogen and one fifth oxygen, not, however, chemical-
ly 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 com-
pounds, viz.

^?n^' f S Protoxide of Nitrogen, nitrous

i>U torm ^ oxide, or exhilarating gas.

^^ C Binoxide of Nitrogen

( or Nitric oxide.
" Hyponitrous acid.
** Nitrous acid.
" Nitric acid.
For other details, see Webster's Chemistry, 3d edit., p. 134, &c;

JVitrog.
100

lOO

100

100
100
100

150
200
250

26 OF THE CONSTITUENT ELEMENTS OF PLANTS.

life has ceased to exercise its influence, this element
resumes its chemical character, and materially assists
in promoting the decay of vegetable matter, by es-
caping from the compounds of which it formed a
constituent.

Oxygen, the only remaining constituent of organic
matter, is a gaseous element, which plays a most
important part in the economy of nature. It is the
agent employed in effecting the union and disunion
of a vast number of compounds. It is superior to
all other elements in the extensive range of its af-
finities. The phenomena of combustion and decay
are examples of the exercise of its power.

Oxygen is the most generally diffused element on
the surface of the earth ; for, besides constituting
the principal part of the atmosphere which surrounds
it, it is a component of almost all the earths and
minerals found on its surface. In an isolated state
it is a gaseous body, possessed of neither taste nor
smell. It is slightly soluble in water, and hence is
usually found dissolved in rain and snow, as well as
in the water of running streams.

Such are the principal characters of the elements
which constitute organic matter ; but it remains for
us to consider in what form they are united in plants.

The substances which constitute the principal mass
of every vegetable are compounds of carbon with ox-
ygen and hydrogen, in the proper relative propor-
tions for forming water. Woody fibre, starch, sugar,
and gum, for example, are such compounds of carbon
with the elements of water. In another class of sub-
stances containing carbon as an element, oxygen and
hydrogen are again present ; but the proportion of
oxygen is greater than would be required for produc-
ing water by union with the hydrogen. The numer-
ous organic acids met with in plants belong, with
few exceptions, to this class.

A third class of vegetable compounds contains car-
bon and hydrogen, but no oxygen, or less of that
element than would be required to convert all the

OF THE COMPOSITION OF THE ATMOSPHERE. 27

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 me-
tallic oxides I for these metallic oxides exist in
every plant, and may be detected in its ashes after
incineration.

Nitrogen is an element of vegetable albumen and
gluten ; it is a constituent of the acid, 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 composi-
tion 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 development of a plant requires the presence,
first, of substances containing carbon and nitrogen,
and capable of yielding these elements to the grow-
ing organism ; secondly, of water and its elements ;
and lastly, of a soil to furnish the inorganic matters
which are likewise essential to vegetable life.

OF THE COMPOSITION OF THE ATMOSPHERE.

In the normal state of growth, plants can only
derive their nourishment from the atmosphere and
the soil. Hence it is of importance to be acquainted
with the composition of these, in order that we may
be enabled to judge from which of their constituents
the nourishment is afforded.

The composition of the atmosphere has been exam-

28 OF THE COMPOSITION OF THE ATMOSPHERE.

ined by many chemists with great care, and the results
of their researches have shown, that its principal
constituents are always present in the same propor-
tion. These are the two gases, oxygen and nitro-
gen, the general properties of which have been
already described. One hundred parts, by weight,
of atmospheric air contain 23*1 parts of oxygen,
and 76*9 parts of nitrogen ; or 100 volumes of air
contain nearly 21 volumes of oxygen gas. From
the extensive range of affinity which this gas pos-
sesses, it is obvious, that were it alone to constitute
our atmosphere, and left unchecked to exert its
powerful effects, all nature would be one scene of
universal destruction. It is on this account that
nitrogen is present in the air in so large proportion.
It is peculiarly adapted for this purpose, as it does
not possess any disposition to unite with oxygen,
and exerts no action upon the processes proceeding
on the earth. These two gases are intimately mixed,
by virtue of a property which all gases possess in
common, of diffusing themselves equally through
every part of another gas, with which they are
placed in contact.

Although oxygen and nitrogen form the principal
constituents of the atmosphere, yet they are not the
only substances found in it. Watery vapor and
carbonic acid gas materially modify its properties.
The former of these falls upon the earth as rain, and
brings with it any soluble matter which it meets in
its passage through the air.

Carbonic acid gas is discharged in immense quan-
tities from the active volcanoes of America, and
from many of the mineral springs which abound in
various parts of Europe; it is also generated during
the combustion and decay of organic matter. It is
not, therefore, surprising that it should have been
detected in every part of the atmosphere in which
its presence has been looked for. Saussure found it
even in the air on the summit of Mont Blanc, which
is covered with perpetual snow, and where it could

OF SOILS. 29

not have been produced by the immediate agency of
vegetable matter. Carbonic acid gas performs a
most important part in the process of vegetable
nutrition, the consideration of which belongs to
another part of the work.

Carbonic acid, water, and ammonia (a compound
of hydrogen and nitrogen) are the final products of
the decay of animal and vegetable matter. In an
isolated condition, they usually exist in the gaseous
form. Hence, on their formation, they must escape
into the atmosphere. But ammonia has not hitherto
been enumerated amongst the constituents of the
air, although, according to our view, it can never be
absent. The reason of this is, that it exists in
extremely minute quantity in the amount of air usu-
ally subjected to experiment in chemical analysis;
it has consequently escaped detection. But rain
which falls through a large extent of air, carries
down in solution all that remains in suspension in it.
Now ammonia always exists in rain-water, and from
this fact we must conclude that it is invariably pres-
ent in the atmosphere. Nor can we be surprised at
its presence when we consider that many volcanoes
now in activity emit large quantities of it.* This
subject will, however, be discussed more fully in
another part of the work.

Such are the principal constituents of the atmo-
sphere from which plants derive their nourishment;
for although other matters are supposed to exist in
it in minute quantity, yet they do not exercise any
influence on vegetation, nor has even their presence
been satisfactorily demonstrated.

OF SOILS.

A soil may be considered a magazine of inorganic
matters, which are prepared by the plant to suit the

* The annual evolution of carbonic acid from springs and fissures in the
ancient volcanic district of the Eifel, on the Rhine, has been estimated by
Bischof, at not less than 100,000 tons, containing 27,000 tons of carbon.

30 OF THE ASSIMILATION OF CARBON.

purposes for which they are destined in its nutrition.
The composition and uses of such substances cannot,
however, be studied with advantage, until we have
considered the manner in w^hich the organic matter
is obtained by plants.

Some virgin soils, such as those of America, con-
tain vegetable matter in large proportion ; and as
these have been found eminently adapted for the
cultivation of most plants, the organic matter con-
tained in them has naturally been recognised as the
cause of their fertility. To this matter, the term
" vegetable mould '^ or humus has been applied.
Indeed, this peculiar substance appears to play such
an important part in the phenomena of vegetation,
that vegetable physiologists have been induced to
ascribe the fertility of every soil to its presence. It
is believed by many to be the principal nutriment of
plants, and is supposed to be extracted by them
from the soil in which they grow. It is itself the
product of the decay of vegetable matter, and must
therefore contain many of the constituents which
are found in plants during life. Its action will
therefore be examined in considering whence these
constituents are derived.

CHAPTER II.

OF THE ASSIMILATION OF CARBON.

COMPOSITION OF HUMUS.

The humus, to which allusion has been made, is
described by chemists as a brown substance easily
soluble in alkalies, but only slightly so 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

COMPOSITION OF HUMUS. 31

humus, and humiii, are names applied to modifica-
tions of humus. They are obtained by treating peat,
woody fibre, soot, or brown coal with alkalies ; by
decomposing 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 names given to these substances might cause
it to be supposed that their composition is identical.
But a more erroneous notion could not be enter-
tained ; since even sugar, acetic acid, and resin do
not differ more widely in the proportions of their
constituent elements, than do the various modifica-
tions of humus.

Humic acid formed by the action of hydrate f of

* The soluble matters were formerly called by the eminent Swedish
chemist Berzelius, extract of humuSy and the insoluble geine (from the
Greek y?7, the earth) , also apotheme and carbonaceous humus. 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.

See Professor Hitchcock's Report, and American Journal of Science,
Vol. XXXVL, Art. XII.

Dr. S. L. Dana considers geine as forming the basis of all the nour-
ishing part of all vegetable manures, and, in the three states of" vegeta-
ble 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 State
of Massachusetts f 1840, Dr. Dana remarks, that geine "is the decom-
posed organic matter of the soil. It is the product of putrefaction ;
continually subjected to air and moisture, it is finally wholly dissipated
in air, leaving only the inorganic bases of the plant, with which it was
once combined. Now, whetner 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, requir-
ing 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 soluble geine,
no matter how compound our chemistry may teach this substance to
be." Page 191.

f Hydrates are compounds of oxides, salts, &c., with definite quan-
tities of water, — a substance from wlych all the water has been re-
moved is anhydrous. Even after exposure to a red heat, caustic potash
retains water.

32 OF THE ASSIMILATION OF CARBON.

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 produced by the action of dilute sul-
phuric 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 re-
spective cases has been found to agree with the
estimates 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 difference in the methods of analysis or
degrees of expertness 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 pro-
portions for forming water ; while, according to
Sprengel, the oxygen is in excess, and Peligot even
estimates the quantity of oxygen at 14 equivalents,
and the hydrogen at only 6 equivalents, making the
deficiency of hydrogen as great as 8 equivalents.
And although Mulder * has very recently explained
many of these conflicting results, by showing that
there are several kinds of humus and humic acids
essentially distinct in their characters, and fixed in
their composition, yet he has afforded no proof that
the definite compounds obtained by him really exist,
as such, in the soil. On the contrary, they appear
to have been formed by the action of the potash and
ammonia, which he employed in their preparation.

It is quite evident, therefore, that chemists have
been in the habit of designating all products of the
decomposition of organic bodies which had a brown
or brownish-black, color by the names of humic

* Bulletin des Scienc. Phys. et Natur. de Neerl. 1840, p. 1-102.

PROPERTIES OF HUMUS. 33

acid or hiimin, according 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 de-
composition of vegetable matters exists in nature in
the form and endowed with the properties of the
vegetable constituents of mould; there is not the
shadow of a proof that one of them exerts any influ-
ence on the growth of plants either in the way of
nourishment or otherwise.

Vegetable physiologists have, without any appar-
ent reason, imputed the known properties of the
humus and humic adds of chemists to that constitu-
ent of mould which has received the same name, and
L 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
extracted 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
considered by many as so firmly established, that any
new argument in its favor has been deemed unneces-
sary; the obvious difference in the growth of plants,
according to the known abundance or scarcity of
humus in the soil, seemed to afford incontestable
proof of its correctness.''^

Yet, this position, when submitted to a strict ex-
amination, 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

* This remark applies more to German than to English botanists and
physiologists. In England, the idea that humus, as such, affords nour-
ishment to plants is by no means general ; but on the Continent, the
views of Berzelius on this subject have been almost universally adopt-
ed.—Ed.

34 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 im-
provement in that most important of all arts is in-
conceivable, without a deeper and more perfect ac-
quaintance with the substances 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 hu-
mus of vegetable physiologists to be really endowed
with the properties recognised by chemists in the
brownish black deposits, which they obtain by pre-
cipitating an alkaline decoction of mould or peat by
means of acids, and which they name humic acid,^

Humic acid, when first precipitated, is a flocculent
substance, is soluble in 2500 times its weight of wa-
ter, and combines with alkalies, lime and magnesia,
forming compounds of the same degree of solubility.
(Sprengel.)

Vegetable physiologists agree in the supposition
that by the aid of water humus is rendered capable .

* 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 peculiar substance
which has been observed in certain sulphureous mineral waters, and
was first noticed by Vauquelin {Jinn, de Chim. XXXIX. 173), who de-
scribed several of its properties and considered it analogous to gelatin.
An account of it was drawn up by M. Anglada, of Montpellier, and
communicated to the Royal Academy of Medicine of Paris, in 1827. It
gelatinizes with water when sufficiently concentrated. Sometimes it is
white, and at others of a red color; when dried it shrinks to ^th of its
bulk when moist. It saturates ammonia, and decomposes several me-
tallic salts. It is destitute of smell and taste. It does not glne sub-
stances together like gelatin and albumen. It yields animonia by de-
composition, and is capable of putrefaction like animal bodies. The
general opinion is, that it is of vegetable origin, and allied to the genUs
tremella, though its existence in mineral waters has not been account-
ed for. Thomson's Oraranic Chemistry, 694. I found it very abun-
dant about the hot sulphureous waters of the island of St. Michael,
Azores. — IV,

ABSORPTION OF HUMUS. 35

of being absorbed by the roots of plants. But ac-
cording 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 tempera-
ture. (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
assimilated by plants. So that, if it is absorbed by
plants, it must be in some altered form.

The correctness of these observations is easily
demonstrated 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
materials ; and I have myself verified this observa-
tion on the decayed wood of beech and fir.

These facts, which show that humic acid, in its
unaltered condition, cannot serve for the nourishment
of plants, have not escaped the notice of physiolo-
gists ; and hence they have assumed that the lime or
the diff*erent alkalies, found in the ashes of vegeta-
bles,render soluble the humic acid and fit it for the
process of assimilation.

Alkalies and alkaline earths do exist in the differ-
ent 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 alkaline bases contained in the ashes of plants,
let us calculate the amount of humic acid which
might be assimilated in this manner. Let us admit,
likewise, that potash, soda, and the oxides of iron

36 OF THE ASSIMILATION OF CARBON.

and manganese have the same capacity of saturation
as lime with respect to humic 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 sul-
phate of potash were extracted, 53 lbs. consisted of
the basic metallic oxides, potash, soda, lime, magne-
sia, iron, and manganese.

One Hessian acre* of woodland yields annually,
according to Dr. Heyer, on an average, 2920 lbs. of
dry fir-wood, which contain 6.17 lbs. of metallic
oxides.

Now, according to the estimates of Malaguti and
Sprengel, 1 lb. of lime combines chemically with 12
lbs. of humic acid; 6.17 lbs. of the metallic oxides
would accordingly introduce into the trees 74.04 of
humic acid, which, admitting humic acid to contain
58 per cent, of carbon, would correspond to 100 lbs.
of dry wood. But we have seen that 2920 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
calculated from the known proportion of metallic
oxides existing 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 1 Hessian acre would receive in that
way 63 lbs. of humic acid, corresponding to 93.6 lbs.
of woody fibre. But the extent of land just men-
tioned produces, independently of the roots and
grain, 1961 lbs. 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

* One Hessian acre is equal to 40,000 square feet, Hessian, or 26,910
square feet, English measure. — P.

ABSORPTION OF HUMUS. 37

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
circumstances, 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 19.3 lbs. over every square foot of
surface; 1 Hessian acre, or 26,910 square feet, con-
sequently receive 519,363 lbs. 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
humate of lime (the most soluble of the humates,
and that which contains the largest proportion of
humic acid) ; then the plants thus nourished would
not receive more than 330 lbs. 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 2843 lbs. of corn (in grain and straw, the
toots not included), or 22,000 lbs. of beet-root
(without the leaves and small radical fibres). It is
quite evident that the 330 lbs. of humic acid, sup-
posed to be absorbed, cannot account for the quan-
tity of carbon 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
earth 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.

38 OF THE ASSIMILATION OF CARBON.

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.

Fertile land produces carbon in the form of wood,
hay, grain, and other kinds of growth, the masses
of which differ in a remarkable degree.

2920 lbs. of firs, pines, beeches, &c. grow as wood
upon one Hessian acre of forest-land with an average
soil. The same superficies yields 2755 lbs. of hay.

A similar surface of corn-land gives from 19,000
to 22,004 lbs. of beet-root, or 881 lbs. of rye, and
1961 lbs. of straw, 160 sheaves of 15.4 lbs. each, —
in all, 2843 lbs.

One hundred parts of dry fir-wood contain 38
parts of carbon; therefore, 2920 lbs. contain 1109
lbs. of carbon.

One hundred parts of hay,*" dried in air, contain
44.31 parts carbon. Accordingly, 2755 lbs. of hay
contain 1110 lbs. of carbon.

Beet-roots contain from 89 to 89.5 parts water,
and from 10.5 to 11 parts solid matter, which con-
sists of from 8 to 9 per cent, sugar, and from 2 to
2i per cent, cellular tissue. Sugar contains 42.4
per cent.; cellular tissue, 47 per cent, of carbon.

22,004 lbs. of beet-root, therefore, if they contain
9 per cent, of sugar, and 2 per cent, of cellular tis-
sue, would yield 1031 lbs. of carbon, of which 833
lbs. would be due to the sugar, and 198 lbs. to the
cellular tissue ; the carbon of the leaves and small
roots not being included in the calculation.

One hundred parts of straw,! dried in air, contain

* 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 682 of ashes. This gives 45-87 carbon, 576 hydrogen,
31*55 oxygen, and 682 ashes. Hay, dried in the air, loses 11-2 p. c.
water at 100° C. (212 F. ) — {Dr. Will.)

t Straw analyzed in the same manner, and dried at 100° C, gave
4637 p. c. of carbon, 5-68 p. c. of hydrogen, 43-93 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. — (i?r. mil.)

FERTILITY OF DIFFERENT SOILS. 39

38 per cent, of carbon; therefore 1961 lbs. of straw
contain 745 lbs. of carbon. One hundred parts of
corn contain 43 parts of carbon; 882 lbs. must
therefore contain 379 lbs., — in all, 1124 lbs. of car-
bon.

26,910 square feet of wood and meadow land pro-
duce, consequently, 1109 lbs. of carbon; while the
same extent of arable land yields in beet-root,
without leaves, 1032 lbs., or in corn, 1124 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 augments ; 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 forest or meadow, where it is never replaced.
It cannot be conceived that the laws for the nutri-
tion 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 development of plants; but it may be
affirmed with positive certainty, that it neither serves
for the production of the carbon, 'nor has any influ-
ence upon it, because we find that the quantity of
carbon produced by manured lands is not greater

40 OF THE ASSIMILATION OF CARBON.

than that yielded by lands which are not manured.
The discussion as to the manner 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 atmo-
sphere.

In attempting to explain the origin of carbon in
plants, it has never been considered that the ques-
tion is intimately 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
carbon ? and in what form is the carbon contained
in the atmosphere ?

These two questions involve the consideration of
twt) most remarkable natural phenomena, which by
their reciprocal 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 inva-
riable condition of the air with respect to oxygen.
One hundred volumes of air have been found, at
every period and in every climate, to contain 21
volumes of oxygen, with such small deviations that
they must be ascribed to errors of observation.

Although the absolute quantity of oxygen con-
tained in the atmosphere appears very great when
represented by numbers, yet it is not inexhaustible.
One man consumes by respiration 25 cubic feet of
oxygen in 24 hours ; 10 cwt. of charcoal consume
32,066 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 551 millions of
cubic feet of this gas.

When we consider facts such as these, our former

QUANTITY OF OXYGEN IN THE ATMOSPHERE. 41

statement, that the quantity of oxygen in the atmo-
sphere does not diminish in the course of ages,* —
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 oxygen in the
atmosphere is thus invariable ?

The answer to this question depends upon another;
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

* 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 as-
sume 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 miles.
Volume of carbonic acid = 3,862-7 cubic miles.

= cube of 15'7 miles.
The maximum of the carbonic acid contained in the atmosphere has
not here been adopted, but the mean, which is equal to 0-000415. (L.) The
weight of carbon which presses upon each square inch of the earth's
surface being 17*39 grains, on an acre of land will be 7 tons. — (Johnston.)
A man daily consumes 45,000 cubic inches (Parisian). A man
yearly consumes 9505-2 cubic feet. 100 million men yearly consume
9,505,200,000,000 cubic feet.

Hence a thousand million men yearly consume 0- 79745 cubic miles
of oxygen. But the air is rendered incapable of supporting the pro-
cess 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 consumption of oxygen by
animals, and by the process of combustion, is not introduced into the
calculation.

When the air returns from the lungs, the carbonic acid gas amounts,
on an average, to 55th of the whole ; or its quantity is increased one
hundred times. — (Johnston.) A full grown man gives off from his
lungs, in the course of a year, upwards of 100 lbs. of carbon. It is
estimated by Johnston, that at least one third of the carbon of the
food of men is daily returned to the air,

4 ♦

42 OF THE ASSIMILATION OF CARBON.

of carbonic acid, which immediately supply its
place.

The most exact and most recent experiments of
De Saussure, 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 ob-
tained, the proportion of carbonic acid in the atmo-
sphere may be regarded as nearly equal to i^^ioth part
of its weight. The quantity varies according to the
seasons ; but the yearly average remains continually
the same.

We have no reason to believe that this proportion
was less in past ages ; and nevertheless, the im-
mense masses of carbonic acid which annually flow
into the atmosphere from so many sources, ought per-
ceptibly 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 replacing the oxygen, which is re-
moved from the air by the processes of combustion
and putrefaction, as w^ell as by the respiration of
animals.

Both these causes are united in the process of
vegetable life.

The facts which we have stated in the preceding
pages prove, that the carbon of plants must be de-
rived 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.

LIBERATION OF OXYGEN. 43

It has been already mentioned likewise, that car-
bon and the elements of water form the principal
constituents of vegetables; the quantity of the sub-
stances which do not possess this composition being
in a very small proportion. Now, the relative quan-
tity of oxygen in the whole mass is less than in car-
bonic acid; for the latter contains tw^o equivalents
of oxygen, whilst one only is required to unite with
hydrogen in the proportion to form water. The veg-
etable products which contain oxygen in larger pro-
portion than this, are, comparatively, few in number;
indeed in many the hydrogen is in great excess. It
is obvious, that w^hen the hydrogen of water is as-
similated by a plant, the oxygen in combination with
it must be liberated, and will afford a quantity of
this element sufficient for the wants of the plants.
If this be the case, the oxygen contained in the car-
bonic acid is quite unnecessary in the process of
vegetable nutrition, and it will consequently escape
into the atmosphere in a gaseous form. It is there-
fore certain, that plants must possess the power of
decomposing 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 re-
turned to the atmosphere, whilst the carbon enters
into combination with water or its elements. The
atmosphere must thus receive a volume of oxygen
for every volume of carbonic acid which has been
decomposed.

This remarkable property of plants has been de-
monstrated 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 carbonic acid, and emit an equal volume
of oxygen. They possess this property quite inde-
pendently of the plant ; for if, after being separated
from the stem, they are placed in water containing
carbonic acid, and exposed in that condition to the

44 OF THE ASSIMILATION OF CARBON.

sun's light, 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 car-
bonic 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 al-
kali 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 de-
pendent 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 respira-
tion ; for besides separating all noxious matters from
the atmosphere, they are an inexhaustible source of
pure oxygen, which supplies the loss which the air
is constantly sustaining. Animals on the other hand
expire carbon, which plants inspire ; and thus the
composition of the medium in which both exist, name-
ly, the atmosphere, is maintained constantly un-
changed.

It may be asked, — Is the quantity of carbonic acid

ITS SOURCE THE ATMOSPHERE. 45

in the atmosphere, which scarcely amounts to ^th
per cent., sufficient for the wants of the whole vege-
tation on the surface of the earth, — is it possible
that the carbon of plants has its origin from the air
alone 1 This question is very easily answered. It
is known, that a column of air of 2441 lbs. weight
rests upon every square Hessian foot (=0*567 square
foot English) of the surface of the'^arth; the diame-
ter of the earth and its superficies are likewise known,
so that the weight of the atmosphere can be calcu-
lated 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 3306
billion 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 ade-
quate to all the purposes for which it is required.
The quantity 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 the volume of the air, or i^th of its weight,
is abstracted from it during every second of time,
for eight hours daily, by a field of 53,820 square feet
( = 2 Hessian acres); then those leaves would re-
ceive 1102 lbs. of carbon in 200 days.*

* The quantity of carbonic acid which can be extracted from the air
in a given time, is shown by the following calculation. During the
white- washing 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 0732
grammes. Upon the 105 square metres already mentioned there must

46 OF THE ASSIMILATION OF CARBON.

But it is inconceivable, that the functions of the
organs- 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 independ-
ent of solar light. During the day, when plants are
in the shade, and during 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 instant that the rays of
the sun strike them. As soon as a young plant
breaks through the surface of the ground, 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 nutri-
tion 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 during our
winter.

accordingly be formed 7686 grammes of carbonate of lime, which con-
tain 4325-6 grammes of carbonic acid. The weight of one cubic deci-
metre of carbonic acid being calculated at two grammes, (more accu-
rately 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 = 1818
cubic feet of carbonic acid in four days. In 200 days it would absorb
2575 cubic metres = 904,401 cubic feet, which contain 11,353 lbs. of
carbonic acid, of which 3304 lbs. are carbon, a quantity three times as
great as that which is assimilated by the leaves and roots growing upon
the same space. — L.

* Plants that grow in the dark, are well known to be colorless. This
is seen in the blanching of celery (etiolation), the earth is heaped
around the stalks to exclude the light.

ITS SOURCE THE ATMOSPHERE. 47

The experiments of De Saussure have proved,
that the upper strata of the air contain more car-
bonic acid than the lower, which are in contact with
plants ; and that the quantity is greater by night
than by day, when it undergoes decomposition.

Plants thus improve the air, by the removal of
carbonic 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 in-
terchange of air between the upper and lower strata,
which their difference of temperature causes, is
extremely trifling when compared with the horizon-
tal movements of the winds. Thus 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 various layers of wood and mineral^coal, as
well as peat, form the remains of a primeval vegeta-
tion. The carbon which they contain must have
been originally in the atmosphere as carbonic acid,
in which form it was assimilated by the plants which
constitute these formations. It follows from this,
that the atmosphere must be richer in oxygen at the
present time than in former periods of the earth's
history. The increase must be exactly proportional
to the quantity of carbon and hydrogen contained
in these carboniferous deposits. Thus, during the
formation of 353 cubic feet of Newcastle splint-coal,
the atmosphere must have received 643 cubic feet
of oxygen produced from the carbonic acid assim-
ilated, and also 158 cubic feet of the same gas
resulting from the decomposition of water. In
former ages, therefore, the atmosphere must have
contained less oxygen, but a much larger proportion
of carbonic acid, than it does at the present time,
a circumstance which accounts for the richness and
luxuriance of the earlier vegetation.

But a certain period must have arrived in which
the quantity of carbonic acid contained in the air

48 OF THE ASSIMILATION OF CARBON.

experienced neither increase nor diminution in any-
appreciable quantity. For if it received an addi-
tional quantity to its usual proportion, an increased
vegetation would be the natural consequence, and
the excess would thus be speedily removed. And,
on the other hand, if the gas was less than the
normal quantity, the progress of vegetation would
be retarded, and the proportion would soon attain
its proper standard.

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 genera-
tion of oxygen. 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. The reverse is the case in the nutrition
of animals. Hence such substances as sugar, starch,
and gum, which are themselves products of plants,
cannot be adapted for assimilation. And this is
rendered certain by the experiments of vegetable
physiologists, who have shown that aqueous solutions
of these bodies are imbibed 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 assimilation than that of
gum, starch, and sugar, for they all contain the
elements of woody fibre, and nearly in the same pro-
portions.

In the second part of the work we shall adduce
satisfactory proofs that decayed woody fibre {humus)
contains carbon and the elements of water, without
an excess of oxygen ; its composition differing from
that of woody fibre in its being richer in carbon.

Misled by this simplicity in its constitution, phy-
siologists found no difficulty in discovering the mode
of the formation of woody fibre ; for they say,* hu-

* Meyen, PJlanzenphysiologief II. S. 141.

SEPARATION OF OXYGEN. 49

mus has only to enter into combination with water,
in order to effect the formation of woody fibre, and
other substances similarly composed, such as sugar,
starch, and gum. But they forget, that their own
experiments have sufficiently demonstrated the inapt-
itude of these substances for assimilation.

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 con-
tain 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 sub-
stances. Smithson, Jameson, and Thomson, found
that the black excretions of unhealthy elms, oaks,
and horse-chesnuts, consisted of humic acid in com-
bination with alkalies. Berzelius 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
absorption of carbon from the atmosphere by plants
is doubted by all botanists and vegetable physiolo-
gists, and that by the greater number the purification
of the air by means of them is wholly denied ?

The action of plants on the air in the absence of
light, that is during night, has been much miscon-
ceived by botanists, and from this we may trace
most of the errors which abound in the greater part
of their writings. The experiments of Ingenhouss
were in a great degree the cause of this uncertainty
of opinion regarding the influence of plants in puri-
fying the air. His observation, that green plants
emit carbonic acid in the dark, led De Saussure and

60 OF THE ASSIMILATION OF CARBON.

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 observation and the utmost ignorance
of the chemical relations of plants to the atmo-
sphere, can account for their adoption.

It is known that nitrogen, hydrogen, and a num-
ber of other gases, exercise a peculiar, and in gen-
eral an injurious influence upon living plants. Is it,
then, probable, that oxygen, one of the most ener-
getic agents in nature, should remain without influ-
ence 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
consequence 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 con-
nected with 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
plants being known, it is a matter of the greatest
ease and certainty to calculate which of them, dur-
ing life, should absorb most oxygen by chemical
action when the influence of light is withdrawn.

The leaves and green parts of all plants contain-
ing 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 com-

INFLUENCE OF THE SHADE ON PLANTS. 51

pounds in which nitrogen is present, ought to absorb
more oxygen than those which do not contain such
matters. The correctness of these inferences has
been distinctly proved by the observations of De
Saussure ; for, whilst the tasteless leaves of the
Agave americana 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 Rohur
containing tannic acid 14 times, and the balmy leaves
of the Populus alba 21 times that quantity. This
chemical action is shown very plainly, also, in the
leaves of the Cotyledon calycinum, the Cacalia
JicoideSj and others ; for they are sour like sorrel in
the morning, tasteless at noon, and bitter in the
evening. The formation 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 compounds containing oxygen and
hydrogen, either in the same proportions as in water,
or even with an excess of hydrogen, which is the
composition of all tasteless and bitter substances.

Indeed the quantity of oxygen absorbed could be
estimated pretty nearly by the different periods
which 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 aquifolium, 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 9J 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,

52 OF THE ASSIMILATION OF CARBON.

with exclusion 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 diminu-
tion 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 vege-
table 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 ab-
sorbing 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 w^ood,
dried by exposure to the atmosphere and then moist-
ened, converts the oxygen into carbonic acid, with-
out change of volume ; fresh wood, therefore, absorbs
most oxygen.

MM. Petersen and Schodler have shown, by the
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 dried 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 ^^ more hydrogen
than corresponds to this proportion. In Finns
Larix, P. Abies, and P. picea, the excess of hydro-
gen amounts to ^, and in Tilia europcea to §. 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

EVOLUTION OF CARBONIC ACID DURING THE NIGHT. 53

wood (^Diospyros Ehenum) the oxygen and hydrogen
are in exactly the same proportion as in water.

The difference between the composition of the
varieties of wood, and that of simple woody fibre,
depends, unquestionably, upon the presence of con-
stituents, in part soluble, and in part insoluble, such
as resin and other matters, which contain a large
proportion of hydrogen : the hydrogen of such sub-
stances being in the analysis of the various woods
superadded to that 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 propor-
tions of its constituents must necessarily have been
different, if the 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 effected by an absorption
of oxygen, and consequent formation of water.

Most vegetable physiologists have connected the
emission of carbonic acid during the night with the
absorption of oxygen from the atmosphere, and have
considered these actions as a true process of respi-
ration in plants, similar to that of animals, and like
it, having for its result the separation of carbon
from some of their constituents. 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 day-
light; it is dissolved 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, con-
tains a certain quantity of moisture which is indis-
pensably necessary to their existence. Carbonic
acid, likewise, is always present in such a soil,
whether it has been abstracted from the air or has

54 OF THE ASSIMILATION OF CARBON.

been generated by the decay of vegetable matter.
Rain and well water, and also that from other
sources, invariably contains 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 atmosphere, along with water, when light
(the cause of the fixation of its carbon) is absent?

Neither this emission of carbonic acid nor the-
absorption of oxygen has any connexion with the
process of assimilation ; nor have they the slightest
relation to one another; the one is a purely me-
chanical, the other a purely chemical process. A
cotton wick, inclosed 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 impressed 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 atmo-
sphere 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 water is completely
excluded from the atmosphere by a clear stratum of
ice, small bubbles of gas are observed to escape, con-

NEGLECT OF CHEMISTRY BY BOTANISTS. 55

tinually, 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
larger bubbles. They consist of pure oxygen gas.
Neither during the night, nor during the day when
the sun does not shine, are they observed to diminish
in quantity. The source of this oxygen is the car-
bonic acid dissolved in the water, which is absorbed
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 exhaled, 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 ad-
mitted, defended, and argued for, by the soundest
and most intelligent natural philosophers, namely, by
Priestley, Sennebier, De Saussure, and even by In-
genhouss 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 dis-
puted 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

56 OF THE ASSIMILATION OF CARBON.

powerful means of help in the acquirement of true
knowledge. They have not been used, because their
study has been neglected.

All discoveries in physics and in chemistry, all
explanations 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 unknown language, which awaken no
thoughts and no associations. They treat these
sciences like the vulgar, who despise a foreign lite-
rature 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 amylin, 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 properties of bodies, be attained
by the microscope ? Is it possible to make the glu-
ten in a piece of bread visible in all its connexions
and ramifications? It is impossible by means of in-
struments ; but if the piece of bread is placed in a
lukewarm decoction of malt, the starch, and the sub-
stance called dextrine,* are seen to dissolve like

* According to Raspail, starch consists of vesicles inclosing within
them a fluid resembling gum. Starch may be put in cold water with-
out being dissolved ; but; when placed in hot water, these spherules

OBJECT OF EXPERIMENTS IN PHYSIOLOGY. 57

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, notwithstand-
ing that leaves generating oil of turpentine or oil of
lemons must possess a different nature from those
in which oxalic acid is formed. Vitality, in its pe-
culiar operations, makes use of a special apparatus
for each function of an organ. A rose-twig engraft-
ed 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 of experimenting is not known in physi-
ology, it being an art which can be learned accurate-
ly only in the chemical laboratory. Nature speaks
to us in a peculiar language, in the language of phe-
nomena ; 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 corresponds to the thought ; while

burst, and allow the escape of the liquid. This liquid is the dextrine
of Biot, so called because it possesses the property of turning the plane
of the polarization of light to the right hand. It is white, insipid, trans-
parent 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 in-
troduced into all kinds of pastries, bread, chocolate, &c. For its prep-
aration, &c., see Ure's Dictionary of Arts and Manufactures fa.nd Web-
ster's Chemistry J 510.

58 OF THE ASSIMILATION OF CARBON.

the opposite result shows that the question was false-
ly stated, and that the conception 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 disre-
garded ; 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 re-
flect that all the time and energy^ of a multitude of
persons of genius, talent, and knowledge, are ex-
pended in endeavors to demonstrate each other's
errors.

The question whether carbonic acid is the food of
plants or not has been made the subject of experi-
ments with perfect zeal and good faith ; the results
have been opposed to that view. But how was the
inquiry instituted ?

The seeds of balsamines, beans, cresses, and
gourds, were sown in pure Carrara marble, and
sprinkled with water containing carbonic acid. The
seeds sprang, but the plants did not attain to the
development of the third small leaf. In other cases,
they allowed the water to penetrate the marble from
below, yet, in spite of this, they died. It is worthy
of observation, that they lived longer with pure dis-
tilled water than with that impregnated with carbon-
ic acid ; but still, in this case also, they eventually
perished. Other experimenters sowed seeds of plants
in flowers of sulphur and sulphate of barytes, 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 ;

CONDITIONS ESSENTIAL TO NUTRITION. 59

but the manner in which they were instituted is op-
posed 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 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 differ-
ent 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 contains 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, if these are given as food, to the
exclusion of, all other substances. Can it be con-
cluded 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; for this it requires
a supply of substances which contain the constitu-
ent elements of its own substance, and are capable
of undergoing transformation. All the organs to-
gether cannot generate a single element, carbon, ni-
trogen, or a metallic oxide.

When the quantity of the food is too great, or is
not capable of undergoing the necessary transform-
ation, or exerts any peculiar chemical action, the or-
gan itself is subjected to. a change : all poisons act
in this manner. The most nutritious substances may
cause death. In experiments such as those describ-
ed above, every condition of nutrition should be con-
sidered. Besides those matters which form their
principal constituent parts, both animals and plants

60 OF THE ASSIMILATION OF CARBON.

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 me-
tallic compounds.

If we knew with certainty that there existed a
substance capable, alone, of nourishing a plant and
of bringing 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 composi-
tion. 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 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 butyric acid. The knowledge of the compo-
sition of milk is a key to the conditions necessary
for the purposes of nutrition of all animals.

All substances which are adequate to the nourish-
ment 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 substance 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 superabun-
dance of food ; it dies in the air, if the demands of
its stomach are not satisfied; and it dies in pure
oxygen gas, however lavishly nourishment be given
to it. Is it hence to be concluded, that neither flesh,

CONDITIONS ESSENTIAL TO NUTRITION. 61

nor air, nor oxygen, is fitted to support life ? Cer-
tainly 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 col-
umn was suspended 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 pedestal could be removed, with-
out the downfall of the column.

Animal and vegetable physiologists, however, come
to such conclusions with respect to the process of
assimilation. They institute experiments, without
being acquainted with the circumstances necessary
for the continuance of life, — with the qualities and
proper nutriment of the animal or plant on which
they operate, — or with the nature and chemical con-
stitution of its organs. These experiments are con-
sidered 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
substance containing nitrogen, which is an essential
constituent of the sap, and indispensable for its pro-
duction ? Must the plant not die, however abundant
the supply of carbonic a^id may be, as soon as the
first small leaves have exhausted the nitrogen con-
tained in the seeds ?

Can a plant be expected to grow in Carrara mar-
ble, even when an azotized substance is supplied to
it, if the marble be sprinkled with an aqueous solu-
tion of carbonic acid, which dissolves the lime and
forms bicarbonate of lime ? A plant of the family of
the PlumbaginecB, upon the leaves of which fine
hornlike, or scaly processes of crystallized carbonate
of lime are formed, might perhaps attain maturity
under such circumstances ; but these experiments
are only sufficient to prove, that cresses, gourds, and
balsamines, cannot be nourished by bicarbonate of

62 OF THE ASSIMILATION OF CARBON.

lime, in the absence of matter containing nitrogen.
We may, indeed, conclude, that the salt of lime acts
as a poison, since the development of plants will ad-
vance further in pure water, when lime and carbonic
acid are not used.

Moist flowers of sulphur attract oxygen from the
atmosphere, and become acid. Is it possible that a
plant can grow and flourish in presence of free sul-
phuric 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 particle of the sulphur to absorb
oxygen and retain it, is present every moment.

When it is known that plants require moisture,
carbonic acid, and air, should we choose, as the soil
for experiments on their growth, sulphate of barytes,
which, from its nature and specific gravity, com-
pletely prevents the access of air.

All these experiments are valueless for the deci-
sion of any question. It is absurd to take for them
any soil, at mere hazard, so long as we are ignorant
of the functions performed in plants by those inor-
ganic substances which are apparently foreign to them.
It is quite impossible to mature a plant of the fam-
ily of the GraminecBj or of the JEquisetacece, the solid
framework of which contains silicate of potash, with-
out silicic acid and potash, or £r plant of the genus
Oxalis without potash, or saline plants such as the
saltworts {^Salsola and Salicornia) w^ithout chloride
of sodium, or at least some salt of similar proper-
ties. All seeds of the GraminecB contain phosphate
of magnesia ; the solid parts of the roots of the
althcBa contain more phosphate of lime than woody
fibre. Are these substances merely accidentally
present ? A plant should not be chosen for experi-
ment, when the matter which it requires for its
assimilation is not w^ell known.

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 nutri-

ON THE ORIGIN AND ACTION OF HUMUS. 63

merit, have been excluded with the greatest care 1
Can the laws of life be investigated in an organized
being which is diseased or dying ?

The mere observation of a wood or meadow is
infinitely better adapted to decide so simple a ques-
tion 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 composition 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 w^e know in what form they
take up their nourishment, and compare its composi-
tion with that of the vegetable substances which
compose their structure.

All these questions will now be examined and
discussed. 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 nitrogen.

CHAPTER III.

ON THE ORIGIN AND ACTION OF HUMUS.

It will be shown in the second part of this work,
that all plants and vegetable structures undergo two
processes of decomposition after death. One of
these is named fermentation ; the other, putrefaction^
decay ^ or eremacausis,*

* The word eremacausis was pi^oposed by the author some time since,
in order to explain the true nature of decay; it is compounded from
ijoiua, by degrees, and xavnig, burning. — TV.

Eremacausis is the act of gradual combination of the combustible

64 ON THE ORIGIN AND ACTION OF HUMUS.

It will likewise be shown, that 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 constit-
uent of all plants) is accompanied by a phenomenon
of a peculiar kind. This substance, in contact with
air or oxygen gas, converts the latter into an equal
volume of carbonic acid, and its decay ceases upon
the disappearance of the oxygen. If the carbonic
acid is removed, and oxygen replaced, its decay
recommences, 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 decomposition, 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 sub-
elements of a body with 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 different 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. Chem. Part 2d.

* In the Appendix to the Third Report of the Agriculture 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 white birch tree was taken from a depth of twenty-five feet below
the surface, in Lowell. **It must have been inhumed there probably
before the creation of man, yet this most perishable of all wood is
nearly as sound as if cut from the forest last fall."

IT EVOLVES CARBONIC ACID. 65.

stances, 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*

The property of woody fibre to convert surround-
ing oxygen gas into carbonic acid diminishes in
proportion as its decay advances, and at last a cer-
tain 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 consti-
tutes 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
carbonic acid, which it emits very slowly. An atmo-
sphere of carbonic acid, formed 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 unob-
structed access of air. An atmosphere 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
nourishment 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 consti-
tuting at the same time a mouth, a lung, and a
stomach. The roots perform the functions 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

* 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.

66 ON THE ORIGIN AND ACTION OF HUMUS.

of carbonic acid; and, on the other hand, the quan-
tity of their food is diminished by every difficulty
which opposes the renewal of air. A plant itself
effects this change of air at a certain 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 fur-
ther required.

Deficiency of moisture in the soil, or its complete
dryness, does not now check the growth of a plant,
provided it receives from the dew and the atmosphere
as much as is requisite for the process of assimila-
tion. During the heat of summer it derives its
carbon exclusively 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 curi-
osities, 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 age. The small parsnep
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 which are destined to convey food to it.

* Teltow is a village near Berlin, where small parsneps are culti-
vated in a sandy soil; they are much esteemed, and weigh rarely
above one ounce. — L.

GROWTH OF PLANTS. 57

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 nour-
ishment 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 re-
turned 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 developed. 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 nutriment
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 necessarily attended with an increase of nutritive
power, and a consequent .further development of new
leaves and branches. Leaves, twigs, and branches,
when completely matured, as they do not become
larger, do not need food for their support. For
their existence as organs, they require only the
means necessary for the performance of the special
functions to which they are destined 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 carbon. These processes are contin-
ually 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 em-
ployed 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

68 ON THE ORIGIN AND ACTION OF HUMUS.

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 influence of the oxygen of the air,
generally suffer 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
"transformation" 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 elements, either grouped in another man-
ner, or in different proportions. Of two compounds
formed in consequence 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 reproduc-
tion 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 trans-
formations, whether the Vital Principle, Increase of

TRANSFORMATIONS OF ORGANIC SUBSTANCES. 69

Temperature, Light, Galvanism, or any other influ-
ence, 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 indi-
cates 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 be-
tween the elements of a body gives rise to a trans-
formation. The elements arrange themselves accord-
ing 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
which their production depended ; and are as innu-
merable as these conditions themselves. The chem-
ical character of an acid, for example, is its unceas-
ing disposition to saturation by means of abase;*
this disposition 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

* Liebig applies the term base to compounds which unite with acids
and neutralize their characters. The product 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 conipounds,
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 ; in 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 simple
radicals, and comports itself in a similar manner to the simple radicals;
that is, it is capable of forming acids and bases.

70 ON THE ORIGIN AND ACTION OF HUMUS.

properties, effect, in most cases, the same kind of
transformations.

Hydrocyanic acid {prus sic acid)* and water con-
tain the elements of carbonic acid, ammonia, urea,
cyanuric acid, cyanilic acid, oxalic acid, formic acid,
Tnelam, ammelin, melamin, azulm^in, m^ellon, hydro-
mellonic acid, allantoin, 6fc.\ It is well known, that
all these very different substances can be obtained

* Cyanogen is considered by Liebig as a compound base, and as
such uniting with oxygen, hydrogen, and most other nonmetaHic
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, «fec., see Webster's Chemistry, 3d edition,

With hydrogen it constitutes hydrocyanic acid.

t Carbonic acid is a gaseous compound of I equivalent of carbon,
and 2 equivalents of oxygen, represented thus, C -f- 20 or c? the two
dots denoting the two of oxygen.

Ammonia consists of 3 equivalents of hydrogen, and 1 equivalent of
nitrogen, represented thus, N -f- 3H, or NH3.

Urea contains the elements of cyanate of ammonia (NH4 O -f- C4 NO),
and exists in urine, from which it is obtained in colorless, transparent
crystals.

Cyanuric acid is a product of the decomposition of chloride of cyan-
ogen, of urea, i&c. It is called a tribasic acid, and its hydrate is thus
represented, Cys O3 + 3HO.

Oxalic acid is a solid acid obtained from several plants, particularly-
of the genera oxalis, rumex, &c. combined with potassa in roots, and
with lime in several kinds of lichens. Oxalate of lime is found in
urinary calculi. It is represented thus, 2CO -j- O (2 equivalents of
carbonic oxide -(- I oxygen). The so-called Essential salt of lemons is
a binoxalate of potash. It is poisonous.

Formic acid, obtained from ants, hence its name. It is now obtained
from sugar and other vegetable substances. Represented by C2 HO3.

Melam is a compound of C12 Nn Hg; it is a white powder insoluble
in water, and, by the action of acids, converted into cyanuric acid and
ammonia.

Ammelin, a saline base, represented thus, Cg N5 H5 O2, a product of
the decomposition of melam by acids and alkalies.

Melamin, a saline base, product of the decomposition of melam,
Cs Ne He, Decomposed by acids into ammonia and ammelid or
ammelin.

Azulmen, the base of azulmic acid, obtained by the decomposition
of cyanogen. The acid is Cs H4 N4 O4.

Mellon, a compound base, a yellow powder. Decomposed into 3
volumes cyanogen and 1 volume nitrogen gas. Ce N4.

Hydromellonic acid is Ce N4 -(- H.

Mlantoinc or allantoic acid occurs in the allantoic fluid of the cow ;
it is formed when uric acid is boiled in water with peroxide of lead.
It is C4 H3 N2 O3 or 2Cy -f- 3H0.

TRANSFORMATIONS OF ORGANIC SUBSTANCES. 71

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
hydrocyanic 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 hydrocyanic acid and water suffer
mutual decomposition. The nitrogen of the hydro-
cyanic 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 simul-
taneous decomposition of hydrocyanic acid and wa-
ter in this instance does not take place in conse-
quence 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 is totally without the sphere of its attractions,
or which, as far as it is concerned, does not exist,
is quite inconceivable. The ammonia in this case is
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 metamorpho-
ses has been especially applied, differ from the ordi-
nary 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 decom-
posed water, and form formic acid, the elements of
this substance with the power of combination being

72 ON THE ORIGIN AND ACTION OF HUMUS.

present. Formic acid here represents the excre-
mentitious matters ; 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
remaining elements, which are not assimilated, com-
bine together and are separated as excrement. The
excrementitious matters of one organ come in con-
tact with another during their passage through the
organism, and in consequence suffer new transfor-
mations ; 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 sulphuretted
hydrogen introduced into the lungs would cause
instant death, but it is formed, under a variety of
circumstances, in the intestinal canal without any
injurious effect.*

In consequence of such transformations as we
have described, excrements are formed of various
composition ; some of these contain carbon in ex-
cess, others nitrogen, and others again hydrogen
and oxygen. The kidneys, liver, and lungs, are or-
gans 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 com-
posed principally of oxygen and hydrogen. Alco-
hol, also, and the volatile oils which are incapable 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

* The danger of breathing carbonic acid gas is well known, but
large quantities can be taken into the stomach with impunity and
even benefit.

TRANSFORMATIONS OF ORGANIC SUBSTANCES. 73

of decomposition generally, the oxygen of the in-
spired 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 uniting with
carbon ; and carbonic acid is disengaged, the car-
bon and oxygen of which must be derived from
matters previously existing in the blood.*

All superabundant nitrogen is eliminated from the
body, as a liquid excrement, through the urinary
passages ; all solid substances, incapable of further
transformation, pass out by the intestinal canal, and
all gaseous matter 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 transfor-
mation of the food, and its assimilation by the
various organs. This is the more necessary, as the
views, hitherto held, have produced no results, and
are quite incapable of useful application.

Is it truly vitality, w^hich 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 assimilation, all the matter introduced
into it ? A decoction of malt possesses as little
power to reproduce itself, as the stomach of a dead
calf; both are, unquestionably, destitute of life.

* The examination of the air expired by consumptive persons, as
well as of their blood, would doubtless throw much light on the nature
of phthisis pulmonalis. Considered in a chemical point of view, the
decojuposition of the blood, as it takes place in the lungs, is a true
process of putrefaction. (See Part II.) The lungs are also the seat
of the transformation of the various substances contained in the blood.
It certainly well merits consideration, that the most approved reme-
dies for counteracting or stopping the progress of this frightful malady
are precisely those which are found most efficacious in retarding putre-
faction. Thus, it is well known, that much relief is afforded by a
residence in works in which empyreumatic oils are manufactured by-
dry distillation, such as manufactories for the preparation of gas or sal-
ammoniac. For the same reason, the respiration of wood vinegar
(pyroligneous acid), of chlorine, and certain of the acids, has been,
recognised as a means of alleviating the disease. — L.

74 ON THE ORIGIN AND ACTION OF HUMUS.

But when amylin or starch is introduced into a de-
coction 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 decoction
of a calf's stomach, to which a few drops of muria-
tic 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 trans-
formation 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 decomposition 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 al-
kaline salts formed by organic acids are carried
through the urinary passages in the form of alkaline
carbonates, capable of dissolving calculi (Wohler).
Is this rational? The medical reports state, that
upon the Rhine, where so much cream of tartar is
consumed in wine, the only cases of calculous dis-
orders are those which are imported from other dis-
tricts. We know that the uric acid calculus is
transformed into the mulberry calculus (which con-
tains 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 circumstances incapable of explanation?

The volatile oil of the roots of valerian may be
obtained from the oil generated during the fermen-
tation of potatoes (Dumas), and the oil of the
SpircBa ulmaria from the crystalline matter of the

* This remarkable action has been completely confirmed in this
laboratory (Giessen), by Dr. Vogel, a highly distinguished young
physiologist. — L.

NATURE OF ORGANIC CHEMICAL PROCESSES. 75

bark of the willow (Piria). We are able to form
in our laboratories formic acid, oxalic acid, urea,
and the crystalline substances 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 relations 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 ex-
traordinary 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 dis-
posal. We shall obtain that which is obtainable
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 considered as of equal value with the terms
specific or dynamic in medicine : everything is specific
which we cannot explain, and dynamic is the ex-
planation of all which we do" not understand ; the
terms having been invented merely for the purpose
of concealing ignorance by the application of learned
epithets.

Transformations of existing compounds are con-
stantly taking place during the whole life of a
plant, in consequence of which, and as the results
of these transformations, there are produced gaseous
matters which are excreted by the leaves and blos-
soms, solid excrements deposited in the bark, and
fluid soluble substances which are eliminated by the
roots. Such secretions are most abundant imme-
diately before the formation and during the con-
tinuance of the blossoms ; they diminish after the
development of the fruit. Substances containing a
large proportion of carbon are excreted by the roots
and absorbed by the soil. Through the expulsion
of these matters unfitted for nutrition, the soil re-
ceives again with usury the carbon which it had at

76 ON THE ORIGIN AND ACTION OF HUMUS.

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 sour-
ces of nutrition to another generation of plants; it
becomes humus. The cultivated soil is thus placed
in a situation exactly analogous to that of forests
and meadows; for 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 receives more carbon in
this form than its decaying humus had lost as car-
bonic acid.

Plants do not exhaust the carbon of a soil in the
normal 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 evident that their growth must depend upon
the reception of nourishment from the atmosphere in
the form of carbonic acid. The influence of 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 pre-
senting a slow and lasting source of carbonic acid,
which is absorbed by the roots, and is the principal
nutriment of young plants at a time when, being des-
titute of leaves, they are unable to extract food from
the atmosphere.

In former periods of the earth's history, its sur-
face was covered with plants, the remains of which
are still found in the coal formations. These plants,
— the gigantic 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 substances contained in their seed.

ITS USE EXPLAINED. 77

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 necessity of the existence of plants such as
these at the commencement of vegetation, must now
be apparent. Humus is a product of the decay of
vegetable matter, and therefore could not have ex-
isted to supply the first plants with the food neces-
sary for the development of the more delicate kinds.
Hence the plants capable of flourishing under such
circumstances could only be those which receive their
nourishment from the air alone. By their decay,
however, the soil in which they grew became sup-
plied with vegetable matter, and the progress of
vegetation must have furnished to the earth materi-
als adapted for the development of those plants,
which depend upon the nutriment contained in the
soil, until those organs are formed which are des-
tined for the assumption of nourishment from the
atmosphere.

The plants of every former period are distinguished
from those of the present by the inconsiderable de-
velopment of their roots. Fruit, leaves, seeds, near-
ly 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 tis-
sue, of which their roots consisted, have been the
first to suffer decomposition. But when we examine
oaks and other trees, which in consequence of revo-
lutions 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
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^
Sedum, and Sempervivum, in proportion to their
mass, and to the surface of their leaves ! Large for-
ests are often found growing in soils absolutely des-

78 ON THE ORIGIN AND ACTION OF HUMUS.

titute of carbonaceous matter; and the extensive
prairies of the Western Continent show that the car-
bon necessary for the sustenance of a plant may be
entirely extracted from the atmosphere. Again, in
the most dry and barren sand, where it is impossible
for nourishment to be obtained through the roots, we
see the milky-juiced plants attain complete perfec-
tion. 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 itself. 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, therefore, be-
come turgid with their juices.

Particular examples might be cited of plants, which
have been brought to mgiturity, upon a small scale,
without the assistance of mould ; but fresh proofs
of the accuracy 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 adduced. It must not, how-
ever, be left unmentioned, that common wood char-
coal, 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 eflicacy.

Plants thrive in powdered charcoal, and may be
brought to blossom and bear fruit if exposed to the
influence of the rain and the atmosphere ; the char-
coal may be previously heated to redness. Charcoal
is the most " indifferent " and most unchangeable
substance known ; it may be kept for centuries with-
out change, and is therefore not subject to decompo-^^
sition. The only substances which it can yield to
plants are some salts, which it contains, amongst
which is silicate of potash. It is known, however,

NOT INDISPENSABLE FOR PLANTS. 79

to possess the power of condensing gases within its
pores, and particularly carbonic acid. And it is by
virtue of this power that the roots of plants are sup-
plied in charcoal, exactly as in humus, with an at-
mosphere of carbonic acid and air, which is renewed
as quickly as it is abstracted.

In charcoal powder, which had been used for this
purpose by Lukas for several years, Buchner found a
brown substance soluble in alkalies. This substance
was evidently 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 atmosphere of nitrogen or carbonic
acid, even thoUgh its roots be fixed in the richest
mould.*

Plants do not, however, attain maturity, under or-
dinary circumstances, in charcoal powder, when they
are moistened with pure distilled water instead of
rain or river water. Rain water must, therefore, con-
tain within it one of the essentials of vegetable life ;
and it will be shown, that this is the presence of a
compound containing nitrogen, the exclusion of which
entirely deprives humus and charcoal of their influ-
ence upon vegetation.

* A few years since I had an opportunity of observing a striking in-
stance of the effect of carbonic acid upon vegetation in the volcanic
island of St. Michael (Azores). The gas issued from a fissure in the
base of a hill of trachyte and tufFa 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 eflfect 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
witli atmospheric air, it had produced less and less effect. — IV.

80 ON THE ASSIMILATION OF HYDROGEN

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) contains carbon and the constituents
of water, or the elements of carbonic acid, together-
with a certain quantity of hydrogen. It has former-
ly been mentioned that water consists of the two
gases, oxygen and hydrogen. The range of affinity
possessed by both these elements is so extensive, that
numerous causes occur which effect the decomposi-
tion of water. Indeed, there is no compound which
plays a more general or more important part in the
phenomena of combination and decomposition. 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 sep-
arated as a gas for every 27*65 parts of carbon,
which are assimilated by a plant ; for this is the
composition of carbonic acid in 100 parts. Or, what
is much more probable, plants, under the same cir-
cumstances, may decompose 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 oxygen, which was
in combination with the hydrogen of the water, and
which exactly corresponds in quantity with the oxy-
gen contained in the carbonic acid, must be separ-
ated in a gaseous form.

Each acre of land, which produces 10 cwts. of
carbon, gives annually to the atmosphere 2865 lbs. of
free oxygen gas. The specific weight of oxygen is

BY THE DECOMPOSITION OF WATER, 81

expressed by the number 1-1026; hence 1 cubic me-
tre of oxygen weighs 3-167 lbs., and 2865 lbs. of
oxygen correspond to 908 cubic metres, or 32,007
cubic feet.

An acre of meadow, wood, or cultivated land in
general replaces, therefore, in the atmosphere as
much oxygen as is exhausted by 10 cwts. of carbon,
either in its ordinary combustion in the air or in the
respiratory process of animals.

It has been mentioned at a former page that pure
woody fibre contains carbon and the component parts
of water, but that ordinary wood contains more hy-
drogen than corresponds to this proportion. This
excess is owing to the presence of the green princi-
ple 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 equivalent of hydrogen appro-
priated by a plant to the production of those sub-
stances. The quantity of oxygen thus set at liberty
cannot be insignificant, for the atmosphere must re-
ceive 547 cubic feet of oxygen for every pound of
hydrogen assimilated.

It has already been stated, that a plant, in the
formation of woody fibre, must always yield to the
atmosphere the same proportional quantity of oxy-
gen ; 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. A little consideration
will show that this must be the case. It has repeat-
edly been stated, that woody fibre contains carbon
in combination with oxygen and hydrogen in the
same proportion in which they exist in water. Water
contains 1 equivalent of each element, whilst carbon-
ic acid consists of 1 equivalent of carbon, united to
2 equivalents of oxygen. In the formation of woody
fibre, 2 equivalents of oxygen must therefore be lib-
erated. The woody fibre can only be formed in one
of two ways : either the carbon of carbonic acid

82 ASSIMILATION OF HYDROGEN

unites directly with water, or the hydrogen of water
combines with the oxygen of the carbonic acid. In
the former of these cases, the two equivalents of ox-
ygen in the carbonic acid must be liberated; in the
latter, two atoms of water must be decomposed, the
hydrogen of which unites with the oxygen of the
carbonic acid, whilst the oxygen of the water, thus
set free, is disengaged in the state of a gas. 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 pos-
sess 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 of Humboldt on the fungi, that water
may be decomposed without the assimilation of hy-
drogen. Water is -a remarkable combination of
two elements, which have the power to separate
themselves from one another, in innumerable pro-
cesses, in a manner imperceptible to our senses ; while
carbonic acid, on the contrary, is only decomposable
by violent chemical action.

Most vegetable structures contain hydrogen in
the form of water, which can be separated as such,
and replaced by other bodies ; but the hydrogen
which is essential to their constitution cannot pos-
sibly exist in the state of water.

All the hydrogen necessary for the formation of
an organic compound is supplied to a plant by the
decomposition of water. The process of assimila-
tion, in its most simple form, consists in the extrac-
tion of hydrogen from water, and carbon from car-
bonic acid, in consequence 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 sub-
stances, or only a part of it is exhaled.

The known composition of the organic compounds

BY THE DECOMPOSITION OF WATER. 83

most generally present in vegetables, enables us to
state in definite proportions the quantity of oxygen
separated during their formation.

36 eq. carbonic acid and 22 eq. hydrogen derived ) „r j ni
from 22 eq. water . ^. . ^ =^ fVoody Fibre,

with the separation of 72 eq. oxygen.

36 eq. carbonic acid and 36 eq. hydrogen derived > ^

from 36 eq. water . . . . 3 ^^^''»

with the separation of 72 eq. oxygen.

36 eq. carbonic acid and 30 eq. hydrogen derived ) o. t

from 30 eq. water . . . . 5 — ^^^^^^>

with the separation of 72 eq. oxygen.

36 eq. carbonic acid and 16 eq. hydrogen derived ) rp • a a

from 1 6 eq. water . . . . 5 " ^ ^^'^^^ -^"^^

with the separation of 64 eq. oxygen.

36 eq. carbonic acid and 18 eq. hydrogen derived > rp . • /i • j

from 18 eq. water .... ^ — lartanc Jiaa,

with the separation of 45 eq. oxygen.

36 eq. carbonic acid and 18 eq. hydrogen derived > jif^7,v add

from 18 eq. water .... 3 '

with the separation of 54 eq. oxygen.
36 eq. carbonic acid and 24 eq. hydrogen derived T ^ ^ .^ . Turpentine,
trom 24 eq. water . . . . i j r t

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. Fruits remain acid in
cold summers ; while the most numerous trees under
the tropics are those which produce oils, caoutchouc,
and other substances containing very little oxygen.
The action of sunshine and influence 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 yellow coloring
matters are formed; tartaric, citric, and tannic acids
disappear, and are replaced by sugar, amylin, or
gum. 6 eq. Tartaric Acid, by absorbing 6 eq. oxy-
gen from the air, form Grape Sugar, with the separa-
tion of 12 eq. carbonic acid. 1 eq. Tannic Acid,
by absorbing 8 eq. oxygen from the air, and 4 eq.

84 ASSIMILATION OF HYDROGEN.

water, form 1 eq. of Amylin, or starch, with separa-
tion of 6 eq. carbonic acid.

We can explain, in a similar manner, the forma-
tion of all the component substances of plants
which contain no nitrogen, whether they are pro-
duced from carbonic 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 representation of their
formation which we have given must not be received
in an absolute sense, it being intended only to ren-
der the nature of the process more capable of ap-
prehension; 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
circumstances in the same proportions.

The vital process in plants is, with reference to
the point we have been considering, the very re-
verse of the chemical processes engaged in the for-
mation of salts. Carbonic acid, zinc, and water,
when brought into contact, act upon one another,
and hydrogen is separated^ 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 process : but the process
of assimilation gives rise to compounds, which con-
tain the elements of carbonic acid and the hydrogen
of water, whilst oxygen is separated.

Decay has been described above as the great
operation of nature, by which that oxygen, which
was assimilated by plants during life, is again re-
turned to the atmosphere. 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 of all of that contained in the carbonic
acid. In the process of putrefaction, a quantity of
water, exactly corresponding to that of the hydro-

pT' SOURCE AND ASSIMILATION OF NITROGEN. 85

gen, 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 quan-
tity of oxygen which they contain ; acids, therefore,
yield more carbonic acid than neutral compounds ;
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 neighborhood of extinct volcanoes, must be
regarded as another means of compensating for the
carbonic acid absorbed and retained by plants dur-
ing life, and consequently as a source by which
oxygen is supplied to the atmosphere. Bischof
calculated that the springs of carbonic acid in the
Eifel (a volcanic district near Coblenz) send into
the air every day more than 99,000 lbs. of carbonic
acid, corresponding to 71,000 lbs. of pure oxygen.

CHAPTER V.

ON THE ORIGIN AND ASSIMILATION OF NITROGEN.

We cannot suppose that a plant could attain
maturity, even in the richest vegetable mould, with-
out the presence of matter containing nitrogen ;
since we know that nitrogen exists in every part of
the vegetable structure. The first and most impor-
tant question to be solved, therefore, is : How and
in what form does nature furnish nitrogen to vege-
table albumen, and gluten, to fruits and seeds 1

This question is susceptible of a very simple solu-
tion.

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

86 SOURCE AND ASSIMILATION OF NITROGEN.

ammonia^ which consists of this element and hydro-
gen. Now, the nitrogen of the air cannot be made
to enter into combination with any element except
oxygen, even by the employment of the most power-
ful chemical means. We have not the slightest
reason for believing that the nitrogen of the atmo-
sphere 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 numerous
facts, showing, that the formation in plants of sub-
stances 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
multitude 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 extremely 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 of ammonia f changes, under the influence
of a high temperature, into hydrocyanic acid and
water, without the separation of any of its elements.

* Ammonia is a compound gas, consisting of one volume of nitrogen
and three volumes of hydrogen. It is produced during the decompo-
sition 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 (p. 70. n.) 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^ Vol.
XXXII. p. 140. See details in Webster's Manual of Chemistry, 3d
edition, p. 374.

Its composition is carbon 2, water 3. With ammonia and other
bases it yields the salts called formates.

SOURCE AND ASSIMILATION OF NITROGEN. 87

Ammonia forms urea,* with cyanic acid,t and a
series of crystalline compounds, with the volatile
oils of mustard and bitter almonds. It changes
into splendid 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 dealhata (^orcin)^ or with the taste-
less matter of the Rocella tinctoria (^erythrin). All
blue coloring matters 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 vegeta-
bles, without exception, the nitrogen which enters
into the composition 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
assistance from other quarters. On this extent of
land there is a certain quantity of nitrogen contained
both in corn and fruit which it produces, and in the
men and animals which feed upon them, and also in
their excrements. We shall suppose this quantity
to be known. The land is cultivated without the
importation of any foreign substance containing
nitrogen. Now, the products of this farm must be
exchanged every year for money, and other necessa-
ries of life — for bodies, therefore, which contain no
nitrogen. A certain proportion of nitrogen is ex-
ported with corn and cattle ; and this exportation
takes place every year, without the smallest com-
pensation ; yet after a given number of years, the
quantity of nitrogen will be found to have increased.

* Urea was discovered in urine, being a constituent of uric acid. It
contains the elements of cyanate of ammonia (NH4 O -f- C4 NO).

t This acid consists of 1 cyanogen and 1 oxygen. See Webster's
Chemistry^ p. 398.

88 SOURCE AND ASSIMILATION OF NITROGEN.

Whence, we may ask, comes this increase of nitro-
gen ? The nitrogen in the excrements cannot repro-
duce itself, and the earth cannot yield it. Plants,
and consequently animals, must, therefore, derive
their nitrogen from the atmosphere.

It will in a subsequent part of this work be shown,
that 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 nitrogen, — ammonia^ — in the tem-
perate and cold climates, and in that of a compound
containing oxygen, — nitric acid, — in the tropics
and hot climates. The formation of the latter is pre-
ceded by the production of the first. Ammonia is
the last product of the putrefaction of animal bodies ;
nitric acid is the product of the transformation 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 nitro-
gen 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 Eglise
des Innocens, at Paris, all the nitrogen contained in
the adipocire was in the state of ammonia."^ Ammo-
nia is the simplest of all compounds of nitrogen;
and hydrogen is the element for which nitrogen pos-
sesses the most powerful affinity.

The nitrogen of putrefied animals is contained in
the atmosphere as ammonia, in the form of a gas

* 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 Jime, that the fat was simi-
lar to spermaceti and to wax, hence he called it adipocire. Its melting
point was 126.5° F.

For notice of the analysis and opinions of other chemists, see Ure's
Dictionary of Arts and ManufactureSy p. 14.

PRODUCTS OF PUTREFACTION. 89

which is capable of entering into combination with
carbonic acid and of forming a volatile salt. Am-
monia in its gaseous form, as well as all its volatile
compounds, is of extreme solubility in water.* Am-
monia, therefore, cannot remain long in the atmo-
sphere, 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 contain ammonia, though
not always in equal quantity. It must be greater in
summer than in spring or in winter, because the in-
tervals 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 we have formerly stated, that all the analyses
of atmospheric air hitherto made have failed to de-
monstrate the presence of ammonia, although, ac-
cording 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 nitro-
gen contained in a cubic foot of air is certainly ex-
tremely small, but, notwithstanding this, the sum of
the quantities of nitrogen from thousands and mil-
lions of dead animals is more than sufficient to sup-
ply all those living at one time with this element.

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 35-3
cubic feet of aqueous vapor are contained in 487
cubic metres, or 17,198 cubic feet of air; 35-3 cubic
feet of aqueous vapor weigh about 1.65 lb. Conse-
quently, if we suppose that the air saturated with
moisture at 59° F. allows all the water which it con-

* According to Dr. Thomson, water absorbs 780 times its bulk of
ammonia.

90 SOURCE AND ASSIMILATION OF NITROGEN.

tains in the gaseous form to fall as rain, then 1*1
pound of rain water must be obtained from every
II5477 cubic feet of air. The whole quantity of am-
monia 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 11,477 cubic feet of air
contain a single grain of ammonia, then ten cubic
inches, — the quantity usually employed in an analy-
sis,— must contain only 0.000,000050 of a grain.
This extremely small proportion is absolutely inap-
preciable 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 all the gas that was diffused through
11,477 cubic feet of air.

If a pound of rain-water contain only Jth of a grain
of ammonia, then a field of 26,910 square feet must
receive annually upwards of 88 lbs. of ammonia, or
71 lbs. of nitrogen ; for by the observations of Schu-
bler, which were formerly alluded to, about 770,000
lbs. of rain fall over this surface in four months, and
consequently the annual fall must be 2,310,000 lbs.
This is much more nitrogen than is contained in the
form of vegetable albumen and gluten, in 2920 lbs.
of wood, 3085 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.f

* A eudiometer is an instrument used in the analyses of the atmo-
sphere. It means a measure of purity. It is also used in the analysis
of mixtures of gases. Several varieties are described in Webster's
Manual^ p. 137.

t The advocates of the importance of humus as a nourishment for
plants, being driven from their position by the facts brought forward in
the preceding chapters, have found in the ammonia of the atmosphere
an explanation of the manner in which humus acquires its solubility,
and therefore its capability of being assimilated by plants. Now, it is
very true that humic acid is soluble in ammonia ; but the humic acid
of chemists is not contained in soils. Were it so, on treating mould with
water we should obtain a dark-colored solution of humate of ammonia.
But we obtain a solution which is entirely devoid of this acid. It cau-

EXISTENCE OF AMMONIA IN RAIN. 91

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 per-
son thought of searching for it.* All the rain-water
employed in this inquiry was collected 600 paces
southwest of Giessen, 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 evaporated with the addi-
tion of a little muriatic acid, a very distinct crystal-
lization 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 sur-
face of the ground in Marcl^ 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.f

It is worthy of observation, that the ammonia con-
tained in rain and snow water possesses an offensive
smell of perspiration and animal excrements, — a
fact which leaves no doubt respecting its origin.

not be too distinctly kept in mind that humic acid is the product of the
decomposition of Awmw^, by means of caustic alkalies. Again, if the
colored solutions of humates of ammonia, lime, or magnesia, be poured
upon good mould or decayed oak-wood (which is nearly pure humus),
and allowed to filter, the solutions are observed to pass through quite
colorless ; they are decolorized just as if they had been filtered through
charcoal. Here, then, humus possesses the property of extracting hu'
mic acid from water ; or, in other words, soils have the power of ren-
dering humic acid insoluble, or unfit for assimilation. — Ep.

* It has been discovered by Mr. Hayes in rain-water in Vermont,
— and in hailstones by M. Girardin, see London and Edinburgh Philo-
sophical Magazine, 1839, Vol. XV. p. 252. See note in Appendix.

t Johnston detected it in snow which fell at Durham, G. B., by add-
ing two drops of sulphuric acid to four pints of snow-water, evaporating
to dryness, and mixing the dry mass with quicklime or caustic potash.
The residual mass contained a brown organic matter, mixed with the
sulphate of ammonia.

92 SOURCE AND ASSIMILATION OF NITROGEN.

Hunefield has proved that all the springs in Greifs-
walde, Wick, Eldena, and Kostenhagen, contain car-
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
ammonia in rain by simply adding a little sulphuric
or muriatic acid to a quantity of rain-wafer, and
evaporating this nearly to dryness in a clean porce-
lain 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 atmo-
sphere by rain and other causes, is as constantly re-
placed by the putrefaction of animal and vegetable
matters. A certain portion 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, produces albumen,
gluten, quinine, morphia, cyanogen, and a number
of other compounds containing nitrogen. The chem-
ical characters of ammonia render it capable of

* Since the appearance of the first edition, this experiment has been
repeated by many in France, Germany, America, and England, and the
existence of ammonia in the atmosphere has been completely confirm-
ed. The assertion, that this ammonia possesses the "offensive smell
of perspiration and animal excrements," has been ridiculed by many
as fanciful, — by none, however, who have made the experiment. The
experiment is so exceedingly easy to perform, that any one may con-
vince himself of the accuracy of the statement. — Ed.

t A small quantity of ammonia water, added to what is commonly
called hard water, will give it the softness of rain or snow water.

EXISTENCE OF AMMONIA IN THE JUICES OF PLANTS. 93

entering into such combinations, and of undergoing
numerous transformations. We have now only to
consider 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 contained in them. This question
is susceptible of easy solution by well-known facts.

In the year 1834, I was engaged with Dr. Wil-
brand, Professor of Botany in the University of
Giessen, in an investigation respecting the quantity
of sugar contained in different varieties of maple-
trees, which grew upon soils which were not ma-
nured. We obtained crystallized sugars from all,
by simply evaporating their juices, without the ad-
dition of any foreign substance ; and we unexpected-
ly 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
refinement. 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 reaction on that of vegeta-
bles. Similar observations were made upon the
juice of the birch tree ; the specimens 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
thousand cubic feet of juice are daily purified with
lime, in order to free it from vegetable albumen and
gluten, and it is afterwards evaporated for crystalli-
zation. Every person who has entered such a manu-
factory 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

94 SOURCE AND ASSIMILATION OF NITROGEN.

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 al-
mond and peach emit much ammonia when treated
with alkalies. (Robiquet.) 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 am-
monia on the addition of lime. Ammonia exists 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 and ammonia, and therefore afford all the con-
ditions necessary for the formation of the azotized
components of the branches, blossoms, and leaves,
as well as of those which contain no azote or nitro-
gen. 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 cultiva-
tion 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 compound of nitrogen in very
different proportions. Proust found French wheat
to contain 12*5 per cent, of gluten; Vogel found that

VARIABLE QUANTITIES OF GLUTEN IN WHEAT. 95

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 difference in the proportion of
the substances containing nitrogen, such as the
gluten which they contain.

Animal manure, in as far as regards the assimila-
tion of nitrogen, acts only by the formation of am-
monia. 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, or
starch; whilst the same quantity, grown on a soil
manured with human urine, yielded the maximum of
gluten, namely 35*1 per cent. Putrefied urine con-
tains nitrogen in the forms of carbonate, phosphate,
and lactate of ammonia, and in no other form than
that of ammoniacal salts.

" Putrid urine is employed in Flanders as a ma-
nure with the best results. During the putrefaction
of urine, ammoniacal salts are formed in large quan-
tity, it may be said exclusively; for under the in-
fluence of heat and moisture, urea, the most promi-
nent ingredient of the urine, is converted into car-
bonate 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
in the South Sea.* It is sufficient to add a small
quantity of guano to a soil, which consists only of

* The guano, which forms a stratum several feet in thickness upon
the surface of these islands, consists of the putrid excrements of in-

96 SOURCE AND ASSIMILATION OF NITROGEN.

sand and clay, in order to procure the richest crop
of maize. The soil itself does not contain the
smallest particle of organic matter, and the manure
employed is formed only of urate, phosphate, oxa-
latej and carbonate of ammonia, together with a few
earthy salts.*"

Ammonia, 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 ordinary gluten.

It is ammonia which yields nitrogen to the vege-
table albumen, the principal constituent of plants ;
and it must be ammonia which forms the red and blue

numerable sea fowl that remain on them during the breeding season.
(See the Chapter on Manures.)

According to Fourcroy and Vauquelin it contains a fourth part of
its weight of uric acid, with ammonia and potash.

The London and Edinburgh Philosophical Magazine, for July, 1841,
contains a new analysis of the guano, made by M. Voelckel in the
laboratory of Professor Wohler,. and confirms what Klaproth found,
viz., that it contains, besides unchanged uric acid, a considerable quan-
tity of two of its usual products of decomposition, viz. oxalic acid and
ammonia. 100 parts of moist guano, contain,

(Voelckel), (Klaproth.)

Urate of ammonia, . . . 9.0 16.0

Oxalate of do 10.6

Do. of lime, .... 7.0 12.75

Phosphate of ammonia, . . . 6.0
Phosphate of ammonia and magnesia, 2.6
Sulphate of potash, .... 5.5

Do. of soda, .... 3.8 common salt 0.05
Chloride of ammonium, . . . 4.2
Phosphate of lime, . . . 14.3 10.00

Clay and sand, .... 4.7 32.00

Undetermined organic substances,"]
of which about 12 per cent, is sol- ( 32.3 28.75

uble in water. A small quantity j

of a soluble salt of iron. Water, J

lOO.O 99.55

Mr. J. H. Blake of Boston, who has recently visited Peru, informs
me, that near Pabellon de Pica there is a high hill, the base of which,
consisting chiefly of guano, is washed by the sea. From this bed,
which is nearly a mile in length, and from 800 to 900 feet high, guano
might be obtained at a cost, which would probably not exceed a cent
ana a half per pound, delivered in the United States. (See also Ap-
pendix.)
* Boussingault. Ann. de Ch. et de Phys. Ixv. p. 319.

COMPOSITION OF EXCREMENTITIOUS MATTER. 97

coloring matters of flowers. Nitrogen is not pre-
sented to wild plants in any other form capable of
assimilation. Ammonia, by its transformation, fur-
nishes nitric acid to the tobacco plant, sun-flower,
Chenopodium, 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 influence 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 phosphates, partly as urea. Urea is con-
verted during putrefaction into carbonate of ammo-
nia, that 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 vegetables 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 hip-
puric acid,* which is decomposed during putrefaction
into benzoic acidf and ammonia. The latter enters
into the composition of the gluten, but the benzoic
acid often remains unchanged : for example, in the
Anthoxanthum odoratum.

The solid excrements of animals contain compar-
atively 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 assimila«
tion to the various organs which they may require

* Rouelle announced the discovery of an acid in the urine of the
horse, which he called henzoic^hni in 1834 Liebig showed that this was
not benzoic acid, but one easily convertible into it, and distinguished it
by the name hippuriCj from Xnnog^ a horse, and ovqov, urine.

t Benzoic acid exists in gum benzoin, &c. ; it is formed, according
to Liebig, by the oxidation of a supposed base called benzule. Its
composition is carbon 14, hydrogen 5, oxygen 2.

98 SOURCE AND ASSIMILATION OF NITROGEN.

for their increase or renewal. Corn, grass, and all
plants, without exception, contain azotized substan-
ces.* 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 in-
creases neither in size nor strength, and sinks under
every exertion. The quantity of rice which an
Indian eats astonishes the European ; but the fact
that rice contains less nitrogen than any other kind
of grain at once explains the circumstance.f

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 diges-
tion 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 quantity of matter

* The late Professor Gorham 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. de Chim. et de Phys.
t. iv. p. 370), this grain is thus constituted.

Carolina rice. Piedmont 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 71 n 10

inff to starch, )

Oil, .... 0.13 0.25

Phosphate of lime, . . 0.13 0.40

99.73 100.00. With tra-

ces of muriate of potash, 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.

FORM IN WHICH AMMONIA IS PRESENTED. 99

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
containing 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 vpon his land. A heap of
manure lying unemployed upon his land would serve
him no more than his neighbors. 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
ammonia, as long as nitrogen exists in them. In
every stage of their putrefaction an escape of am-
monia from them may be induced by moistening them
with a potash ley; the ammonia being apparent to
the senses by a peculiar smell, and by the dense
white vapor which arises when a solid body moist-
ened 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 require for their growth,
for the water which evaporates through their leaves
and blossoms, emits, aft^r some time, a putrid smell,
a peculiarity possessed only by such bodies as con-
tain nitrogen. Cultivated plants receive the same
quantity of nitrogen from the atmosphere as trees,

100 SOURCE AND ASSIMILATION OF NITROGEN.

shrubs, and other wild plants; but this is not suffi-
cient for the purposes of agriculture. Agriculture
differs essentially from the cultivation of forests,
inasmuch as its principal object consists in the pro-
duction 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 conveyed by rain to the soil is
received by plants, becausp 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
which the solid excrements are impregnated, contain
the greatest part of their ammonia in the state of
salts, in a form, therefore, in which it has completely
lost its volatility ; when presented in this condition,
not the smallest portion of the ammonia is lost to
the plants ; it is all dissolved by water, and imbibed
by their roots. The evident 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 am-
monia of the atmosphere, which would otherwise be
volatilized, with the water which evaporates.* The
carbonate of ammonia contained in rain-water is
decomposed by gypsum, in precisely the same man-
ner as in the manufacture of sal-ammoniac. Soluble
sulphate of ammonia and carbonate of lime are
formed ; and this salt of ammonia possessing no
volatility is consequently retained in the soil. All
the gypsum gradually disappears, but its action upon
,—. — _ — »

* It has long been the practice in some parts of the country to strew
the floors of stables with gypsum. This prevents the disagreeable odor
arising from the putrefaction of stable manure, by decomposing the
ammoniacal salts which are formed. — Ed.

USE OF GYPSUM. IQl

'' the carbonate of ammonia continues as long as a
trace of it exists.

The beneficial influence of gypsum and of many-
other salts has been compared to that of aroraatics,
which increase the activity of the human stomach
and intestines, and give a tone to the whole system.
But plants contain no nerves ; we know of no sub-
stance capable of exciting them to intoxication and
madness, or of lulling them to sleep and repose.
No substance can possibly cause their leaves to ap-
propriate a greater quantity of carbon from the
atmosphere, when the other constituents which the
seeds, roots, and leaves require for their growth are
wanting.* The favorable action of small quantities
of aromatics upon man, when mixed with his food,
is undeniable ; but aromatics are given to plants
without 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 really
consists in their giving a fixed condition 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 effect of

* In 1831, 1 suggested to a well known and most successful culti-
vator (Mr. Haggerston), 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
Pelargonium (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
perished. Probably a supply of nutriment proportioned to the increased
demand was not supplied.

The necessity for this supply is now well known, and Pelargoniums
are now grown with great luxuriance and perfection, both of leaves
and flowers, by the free use of " manure water," obtained by steeping
horsedung in rain-water. The soil, too, best adapted to the plants is
chiefly prepared from decayed vegetable matter, derived from decom-
posed leaves and plants, mixed with that from the sods of fields.

102 SOURCE AND ASSIMILATION OF NITROGEN.

gypsum, it may be sufficient to remark, that 110 lbs.
of burned gypsum fixes as much ammonia in the
soil as 6887 lbs. of horse's urine* 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 loss, in the form of carbonate
of ammonia. If we admit with Boussingaultf that
the nitrogen in grass amounts to ^Jq of its weight,
then every pound of nitrogen which we add in-
creases the produce of the meadow 110 lbs., and
this increased produce of 110 lbs. is effected by the
aid of a little more than 4 lbs. of gypsum.

Water is absolutely necessary to effect the decom-
position of the gypsum, on account of its difficult
solubility, (1 part of gypsum requires 400 parts of
water for solution,) and also to assist in the absorp-
tion of the sulphate of ammonia by the plants :
hence it happens, that the influence of gypsum is
not observable on dry fields and meadows. In such
it would be advisable to employ a salt of more easy
solubility, such as chloride of calcium.

The decomposition of gypsum by carbonate of
ammonia does not take place instantaneously; on
the contrary, 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 explained 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

* The urine of the horse contains, according to Fourcroy and Vau-
quelin, in 1000 parts,

Urea ... 7 parts.

Hippurate of soda . . 24 "
Salts and water . . 979 "

1000 parts,
t Boussingault, ^nn. de Ch. et de Phys., t. Ixiii. page 243.

USE OF BURNED CLAY AS A MANURE. 103

in as great a degree : and bedsides, what influence
can be ascribed to a hundred pounds of water spread
over an acre of land, in a condition in which it can-
not be serviceable either by the roots or leaves 1
The true cause is this : —

The oxides of iron and alumina are distinguished
from all other metallic oxides by their power of form-
ing solid compounds with ammonia. The precipi-
tates obtained by the addition of ammonia to salts
of alumina or iron are true salts, in which the ammo-
nia is contained as a base. Minerals containing alu-
mina or oxide of iron also possess, in an eminent de-
gree, the remarkable property of attracting ammonia
from the atmosphere and of retaining it. Vauquelin,
whilst engaged in the trial of a criminal case, discov-
ered that all 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 ammo-
nia, when moistened with caustic potash, that even
after they have been exposed for two days, reddened
litmus paper held over them becomes blue. Soils,
therefore, which contain oxides of iron, and burned
clay, must absorb ammonia, an action which is fa-
vored by their porous condition ; they further pre-
vent the escape of the ammonia once absorbed, by
their chemical properties. Such 'soils, in fact, act
precisely as a mineral acid woufd do, if extensively
spread over their surface; with this difference, that
the acid would penetrate the ground, enter into com-
bination with lime, alumina, and other bases, and
thus lose, in a few hours, its property of absorbing
ammonia from the atmosphere. The addition of
burned clay to soils has also a secondary influence ;

104 SOURCE AND ASSIMILATION OF NITROGEN.

it renders the soil porous, and, therefore, more per-
meable to air and moisture.

The ammonia absorbed by the clay or ferruginous
oxides 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
possesses of condensing ammonia within its pores,
particularly 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 approaches 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 satisfac-
tory means of explaining still further the properties
of humus, or wood in a decaying state. 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 basal-
tic 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 all kinds of soils, in the form of ammo-
nia, as a product of the decay and putrefaction of
preceding generations of animals and vegetables.
We find likewise that the proportion of azotized mat-
ters in plants is augmented by giving them a larger
supply of ammonia conveyed in the form of animal
manure.

No conclusion can then have a better foundation

* In experiments instituted by Dr. Daubeny, with a view of ascer-
taining whether vegetable mould had not the same property, he found
that both carbonic acid and ammoniacal gases were condensed within
its pores, as they would be by a lump of charcoal.

OF THE INORGANIC CONSTITUENTS OF PLANTS. 105

than this, that it is the ammonia of the atmosphere
(^hich furnishes nitrogen to plants.*
Carbonic acid, water, and ammonia, contain the
elements necessary for the suj^port of animals and
vegetables. The same substances are the ultimate
products of the chemical processes of decay and pu-
trefaction. All the innumerable products of vitality
resume, after death, the original form from which
they sprung. And thus death, - — the complete dis-
solution of an existing generation, — becomes the
source of life for a new one.

CHAPTER VI.

OF THE INORGANIC CONSTITUENTS OF PLANTS.

Carbonic acid, water, and ammonia, are necessary
for the existence of plants, because they contain the
elements from which their organs are formed; but
other substances are likewise requisite for the for-
mation of certain organs destined for special func-
tions peculiar to each family of plants. Plants ob-
tain these substances from inorganic nature. In the
ashes left after the incineration of plants, the same
substances are found, although in a changed con-
dition.

Although the vital principle exercises a great pow-
er over chemical forces, yet it does so only by direct-
ing the way in which they are to act, and not by
changing the laws to which they are subject. Hence
when the chemical forces are employed in the pro-
cesses of vegetable nutrition, they must produce the
same results which are observed in ordinary chemical
phenomena. The inorganic matter contained in plants

* From some experiments with respect to the action of light upon
plants, Dr. Daubeny is inclined to suspect that in some cases hydro-
gen is assimilated whilst nitroo-en is disengaged. See his Memoir in
Philos. Trans. 1836.

106 OF THE INORGANIC CONSTITUENTS OF PLANTS.

must, therefore, be subordinate to the laws which
regulate its combinations in common chemical pro-
cesses.

The most importaift division of inorganic substan-
ces is that of acids and alkalies. Both of these have
a tendency to unite together, and form neutral com-
pounds, which are termed salts. According to the
doctrine of equivalents, these combinations are al-
ways effected in definite proportions, that is to say,
one equivalent of an acid always unites with one or
two equivalents of a base, whatever that base may
be. Thus 501*17 parts by weight of sulphuric acid
unite with 1 eq. of potash, and form 1 eq. of sulphate
of potash ; the same quantity unites with 1 eq. of
soda, and produces sulphate of soda. From this
fact follows the rule, — that the quantity, which an
acid requires of an alkali for its saturation, may be
represented by a very simple number.

It is perfectly necessary to form a proper concep-
tion of what chemists denominate the " capacity
for saturation of an acid," before we are able to
form a correct idea of the functions performed in
plants, by their inorganic constituents. The power
of a base to neutralize an acid does not depend
upon the quantity of radical which it contains, but
altogether upon the quantity of its oxygen. Thus
protoxide of iron contains 1 eq. of oxygen, and
unites with 1 eq. of sulphuric acid in forming a
neutral salt ; but peroxide of iron contains 3 eq. of
oxygen, and requires 3 eq. of the same acid for its
neutralization. Hence when a given weight of an
acid is neutralized by different bases, the quantity
of oxygen contained in these bases must be the
same as is exhibited by the following scale : —

501*17 parts of Sulphuric Acid neutralize 258-35 Magnesia Oxygen = 100
" " " 647-29 Strontia " =100

" " " 1451-61 Oxide of Silver " =100

« " " 956-8 Barytes « =100

It follows from the law of equivalents, that the
quantity of oxygen in a base must stand in a simple
relation to the quantity of oxygen in an acid which

IMPORTANCE OF ALKALINE BASES. * 107

unites with it. By this is meant, that the quantities
in both cases must either be equal or multiples of
each other -, for the doctrine of equivalents denies
the possibility of their uniting in fractional parts.
This will be rendered obvious by a consideration of
the two following examples :

100 parts of Cyanic Acid contain 23 26 oxygen = 1.

100 parts of Cyanic Acid saturate 137-21 parts of potash, which contain

23 26 oxygen = 1 .
100 parts of Nitric Acid contain 73-85 oxygen = 5.
100 parts of Nitric Acid saturate 214-40 parts of oxide of silver, which

contain 14 77 oxygen = 1.

In the first of these cases, the relation of the
oxygen of the base to that of the acid is as 1 : 1; in
the second, as 1 : 5. The capacity for saturation
of each acid is, therefore, the constant quantity of
oxygen necessary to neutralize 100 parts of it.

Many of the inorganic constituents vary accord-
ing to the soil in which the plants grow, but a cer-
tain number of them are indispensable to their de-
velopment. All substances in solution in a soil
are absorbed by the roots of plants, exactly as a
sponge imbibes a liquid, and all that it contains,
without selection. The substances thus conveyed
to plants are retained in greater or less quantity, or
are entirely separated when not suited for assimi-
lation.

Phosphate of magnesia in combination with am-
monia 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 con-
tains the greatest quantity of it. It is this salt
which forms large crystalline 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 separates 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

108 OF THE INORGANIC CONSTITUENTS OF PLANTS.

potash, soda, lime, or magnesia. These bases evi-
dently regulate the formation of the acids, for the
diminution of the one is followed by a decrease of
the other : thus in the grape, for example, the quan-
tity 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 simi-
lar 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 con-
veyed to them for assimilation by other parts. The
leaves contain more inorganic matters than the
branches, and the branches more than the stem.
The potato plant contains more potash before blos-
soming than after it.

The acids found in the different families of plants
are of various kinds ; it cannot be supposed that
their presence and peculiarities are the result of
accident. The fumaric and oxalic acids in the liver-
wort, the kinovic acid in the China nova, the ro-
cellic 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 neces-
sary to their life, which is incontestable, it is equally
certain that some alkaline base is also indispensable,
in order to enter into combination with the acids
which are always found in the state of salts. All
plants yield by incineration ashes containing car-
bonic 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

* Salts of organic acids yield carbonates on incineration, if they
contain either alkaline or earthy bases.

INVARIABLE QUANTITY OF ALKALINE BASES. 109

be considered with the strictest attention both by
the agriculturist and physiologist.

We have no reason to believe that a plant in a
condition 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 alka-
line 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 in-
ference be correct, the absent alkali 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 m\ist 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 constituents 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 analysis of
De Saussure and Berthier, that the nature of a soil
exercises 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.

110 OF THE INORGANIC CONSTITUENTS OF PLANTS.

Hence it has been concluded, (erroneously, I be-
lieve,) that the presence of bases exercises no par-
ticular influence 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 analyses 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.

100 parts of the ashes of the pine-tree from Mont
Breven contained —

Carbonate of Potash . 3*60 Quantity of oxygen in the Potash 0*41
'' Lime . 4634 " " " Lime 7-33

" Magnesia 6-77 " « « 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* —

Carbonate of Potash . 7*36 Quantity of oxygen in the Potash 0.85
" Lime . 5119 « " " Lime 810

" Magnesia 00-00

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 demonstrated, which the analyst in this case
had not in view.

Let us now compare Berthier's analyses of the
ashes of tw^o fir-trees, one of which grew in Norway,
the other in Allevard (department 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 dif-

* According to the experiments of Saussure, 1000 parts of the wood of
the pine from Mont Breven gave 11*87 parts of ashes; the same quan-
tity of wood from Mont La Salle yielded 11-28 parts. From this we
might conclude that the two pines, although brought up in different
soils, yet contained the same quantity of inorganic elements.

INVARIABLE QUANTITY OF ALKALINE BASES. HI

ferent plants, and yet even here the quantity of
oxygen in the bases of both was the same.

100 parts of the ashes of firwood from Allevard
contained, according to Berthier, (Ann. de Chim. et
de Phys. t. xxxii. p. 248,)

Potash and Soda 16*8 in which 3*42 parts must be oxygen.
Lime . 29-5 " 8-20 " "

Magnesia . 3-2 " 1.20 " «'

49-5 12-82

Only part of the potash and soda in these ashes
was in combination with organic acids ; the remain-
der was in the form of sulphates, phosphates, and
chlorides. One hundred parts of the ashes contain
3*1 sulphuric acid, 4-2 phosphoric acid, and 0*3 hy-
drochloric acid, which together neutralize a quantity
of base containing 1*20 oxygen. This number there-
fore must be subtracted from 12-82. The remainder
11*62 indicates the quantity of oxygen in the alka-
line bases, combined with organic acids in the fir-
wood of Allevard.

The firwood 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 " 169 '' "

51-45 12 84

And if the quantity of oxygen of the bases in com-
bination with sulphuric and phosphoric 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.

* 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 sensibly the
above proportions. Berthier has not mentioned the proportion of ashes
contained in the wood.

112 OF THE INORGANIC CONSTITUENTS OF PLANTS.

It is not known in what form silica, manganese,
and oxide of iron, are contained in plants ; but we
are certain that potash, soda, and magnesia, can be
extracted from all parts of their structure in the
form of salts of 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 (bitartrate
of potash), 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 exercise 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 saturation of an acid is constant; and
when w^e see oxalate of lime in the lichens occupy-
ing the place of woody fibre which is absent, we
must regard it as certain that the soluble organic
salts are destined to fulfil equally important though
different functions, so much so that we could not
conceive the complete development of a plant with-
out their presence, that is, without the presence of
their acids, and consequently of their bases.

From these considerations we must perceive, that
exact 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 inva-
riable number can be found to express the quantity

SUBSTITUTION OF ALKALINE BASES. 113

of oxygen which each species of plant contains in
the bases united with organic acids. In all proba-
bility 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 necessary 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 suffi-
cient 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 contain only salts of potash, with mere traces
of muriate of soda. (Cadet.)

The examples cited above, in which the quantity
of oxygen contained in the bases was shown to be
the same, lead us to the legitimate conclusion, that
the development of certain plants is not retarded
by the substitution of the bases contained in them.
But it was by no means inferred that any one base
could replace all the others, which are found in a
plant in its normal condition. On the contrary, it
is known that certain bases are indispensable for the
growth of a plant, and these could not be substituted
without injuring its development. Our inference has
been drawn from certain plants, which can bear
without injury this substitution ; and it can only be
extended to those plants which are in the same con-
dition. It will be shown afterwards that corn or
vines can only thrive on soils containing potash, and
that this alkali is perfectly indispensable to their
growth. Experiments have not been sufficiently
multiplied so as to enable us to point out in what
plants potash or soda may be replaced by lime or
magnesia ; we are only warranted in affirming that
such substitutions are in many cases common. The
ashes of various kinds of plants contain very differ-

10*

114 OF THE INORGANIC CONSTITUENTS OF PLANTS.

ent quantities of alkaline bases, such as potash, soda,
lime, or magnesia. When lime exists in the ashes
in large proportion, the quantity of magnesia is di-
minished, and in like manner according as the latter
increases the lime or potash decreases. In many kinds
of ashes not a trace of magnesia can be detected.

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 development 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 poisonous nature, is formed in the sprouts
which extend towards the light, while not the small-
est trace of such a substance can be discovered in
the roots, herbs, blossoms, or fruits of potatoes
grown in fields. (Otto.)* In all the species of the
Cinchona, kinic acid is found ; but the quantity of
quinia, 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 minimum of
the latter, as must necessarily be the case if they
mutually replace one another according to their
equivalents. We know that different kinds of opium
contain meconic acid in combination with very dif-
ferent quantities of narcotina, morphia, codeia, &c.,
the quantity of one of these alkaloids diminishing
on the increase of the others. Thus the smallest

The analysis of potatoes afforded M. Henry

Starch 13.30

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

EXCREMENTS OF PLANTS. 115

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 ex-
ist, they are always found to bear a certain relative
proportion to one another. Attention to these facts
must be very important in the selection of soils des-
tined for the cultivation of plants which yield the
vegetable alkaloids.

Now if it be found, as appears to be the case in
the juice of poppies, that an organic acid may be re-
placed by an inorganic, without impeding the growth
of a plant, we must admit the probability of this sub-
stitution taking place in a much higher degree in the
case of the inorganic bases.

When roots find their more appropriate base in
sufficient quantity, they will take up less of another.

These phenomena do not show themselves so fre-
quently in cultivated plants, because they are sub-
jected to special external conditions for the purpose
of the production of particular constituents or par-
ticular organs.

When the soil, in which a white hyacinth is grow-
ing in a state of blossom, is sprinkled with the juice
of the Phytolacca decandra^^ the white blossoms as-
sume in one or two hours a red color, which again
disappears after a few days under the influence of
sunshine, and they become white and colorless as
before.J 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

* Robiquet did not obtain a trace of meconate of lime from 300 lbs.
of opium, whilst in other kinds the quantity was very considerable.
Ann. de Chim. liii. p. 425.

t American nightshade.

t Biot, in the Comptcs rendus des Stances de VAcadimie des Sciences,
^ Farisy ler S6mestre, 1837, p. 18.

116 OF THE INORGANIC CONSTITUENTS OF PLANTS.

condition is not permanent, and when the blossoms
have again become colorless, none of the coloring
matter remains ; and if it should occur that any of
its elements were adapted for the purposes of nutri-
tion of the plant, then these alone would be retained,
whilst the rest would be excreted in an altered form
by the roots.

Exactly the same thing must happen when we
sprinkle a plant with a solution of chloride of potas-
sium, nitre, or nitrate of strontia ; they will enter
into the different parts of the plant, just as the col-
ored juice mentioned above, and will be found in
its ashes if it should be burnt at this period. Their
presence is merely accidental ; but no conclusion can
be hence deduced against the necessity of the pres-
ence of other bases in plants. The experiments of
Macaire-Princep have shown, that plants made to
vegetate with their roots in a weak solution of ace-
tate of lead, and then in rain-water, yield to the lat-
ter all the salt of lead which they had previously ab-
sorbed. They return, therefore, to the soil all mat-
ters 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 strontia, the salt is absorbed, but it is again sep-
arated by the roots and removed further 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 accu-
rate chemist. One of these grew in Norway, on a
soil the constituents of which never changed, but to
which soluble 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 absorbed it after every shower ?

We can explain the absence of salt in this case by
means of the direct and positive observations refer-

EXCREMENTS OF PLANTS. 117

red to, which have shown that plants have the power
of returning to the soil all substances unnecessary
to their existence ; and the conclusion to which all
the foregoing 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 retained.

The perfect development of a plant, according to
this view, is dependent on the presence of alkalies
or 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 trees, the wood of which contains une-
qual 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 neces-
sary to bring it to complete maturity, exist there in
sufficient quantity. The accuracy of these conclu-
sions, so highly important to agriculture and to the
cultivation of forests, can be proved by the most
evident facts.

All kinds of grasses, the Eqiiisetacece^ for exam-
ple, 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, because it is again conveyed to them as
manure in the form of putrefying straw. But this is

• Berthier, Jinnales de Chimie et de Physique, t. xxx. p. 248.

118 OF THE INORGANIC CONSTITUENTS OF PLANTS.

not the case in a meadow, and hence we never find a
luxuriant crop of grass * on sandy and calcareous
soils, which contain little potash, evidently because
one of the constituents indispensable to the growth
of the plants is wanting. Soils formed from basalt,
grauwacke, and porphyry, are, ccBteris paribus, the
best for meadow-land, on account of the quantity of
potash which enters into their composition. The
potash abstracted by the plants is restored during
the annual irrigation. The potash contained in the
soil itself is inexhaustible in comparison with the
quantity 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 circumstances be restored.
Hence it happens that, after the lapse of several
years, the crops of grass on the meadows manured
with gypsum diminish, owing to the deficiency of
potash. But if the meadow be strewed from time to
time with wood-ashes, even with the lixiviated ashes
which have been used by soap-boilers, (in Germany
much soap is made from the ashes of wood,) then
the grass thrives as luxuriantly as before. The ash-
es are only a means of restoring the potash, f

* It would be of importance to examine what alkalies are contained
in the ashes of the seashore plants which grow in the humid hollows
of downs, and especially in those of the millet-grass. If potash is not
found in them, it must certainly be replaced by soda as in the Salsola^
or by lime as in the Plumbaginece. — L.

t The compost which has been employed with most advantage as 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 alternate
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 undis-
turbed 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 which 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. Accord-
ing to Dr. Ure it contains 20 per cent, of real alkali (soda) with muri-
ates and sulphates of soda, some lime and alumina, with yery little
sulphur.

REPLACEMENT OF EXHAUSTED ALKALIES. 119

A harvest of grain is obtained every thirty or forty
years from the soil of the Luneburg heath, by strew-
ing it with the ashes of the heath-plants (^Erica vul-
garis) which grow on it. These plants during the
long period just mentioned collect the potash and
s-oda, 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 ena-
bled 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
sowing 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 indis-
pensable 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 quan-
tity of alkaline earths sufficient for their own suste-
nance, yet in its ordinary condition it is incapable
of producing grain.

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 increased by manuring them with such
substances as shavings of horn, &c. ; but after some
years the formation of the wood and leaves de-
creased 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 con-
tained 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

120 OF THE INORGANIC CONSTITUENTS OF PLANTS.

of potash, although very little nitrogen. All the
potash, in fact, which is contained in the food con-
sumed 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 ex-
ample of the incapability of a soil to produce wheat
or grasses in general, when it fails in any one of
the materials necessary to their growth. Jn 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 carbonate of that
alkali. The consequence was, that he rendered 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 most potash ; and the quantity of them which is
annually taken from a wood, for the purpose of
being employed as litter,* contains more of that alkali
than all the old wood which is cut down. The bark
and foliage 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 2920 lbs. of firwood which are yearly
removed from an acre of forest, only from 0*125 to
0*58 lbs. of alkalies are abstracted from the soil,
calculating the ashes at 0*83 per cent. The moss,
however, which covers the ground, and of which the
ashes are known to contain so much alkali, con-
tinues uninterrupted 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

* 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 being used as litter for their cattle. The trees, however, were
found to suffer so much in consequence, that their removal is now
strictly prohibited. The cause of the injury was that stated in the
text. — Ed.]

NECESSITY OF CERTAIN CONDITIONS FOR NUTRITION. 121

is supplied to the roots of the trees, and a fresh
supply is rendered unnecessary.

The supposition of alkalies, metallic oxides, or in-
organic matter in general, being produced by plants,
is entirely 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, follow him like the domestic animals. But
saline plants seek the seashore or saline springs,
and the Chenopodiupi the dunghill from similar
causes. Saline plants require common salt, and the
plants which grow only on dunghills need ammonia
and nitrates, and they are attracted whither these
can be found, just as the dung-fly is to animal ex-
crements. 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 com-
bined, and no soil is richer in them than those
where men and animals dwell together ; where the
urine and excrements of these are found corn-plants
appear, because their seeds cannot attain maturity un-
less 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 essential to their life.

Numerous small fish, of not more than two inches
in length ( Gasterosteus aculeatus), are found in the
salt-pans of the graduating house at Nidda (a vil-
lage in Hesse Darmstadt). No living animal is found
in the salt-pans of Neuheim, situated about 18 miles
from Nidda ; but the water there contains so much
carbonic acid and lime, that the walls of the gradu-
ating house are covered with stalactites. Hence
11

122 OF THE INORGANIC CONSTITUENTS OF PLANTS.

the eggs conveyed to this place by birds do not
find the conditions necessary for their development,
which they found in the former place.*

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 tempera-
tures, 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 such bodies, that is, of causing
them to assume the gaseous form. A liquid during
evaporation communicates the power of assuming
the same state in a greater or less degree to all sub-
stances dissolved in it, although they do not of
themselves possess that property.

Boracic acidf is a substance which is completely
fixed in the fire ; it suffers no change of weight ap-
preciable by the most delicate balance, when ex-
posed to a white heat, and, therefore, it is not
volatile. Yet its solution in water cannot be evap-
orated by the gentlest heat, without the escape of a
sensible quantity of the acid with the steam. Hence
it is that a loss is always experienced in the analysis
of minerals containing this acid, when liquids in

* The itch-insect (Acarus Scahiei) is considered by Burdach as the
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 shellfish, trout, and salt-
wort (salicornia). 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 enigmatic,
is, in fact, too seducing for the youthful and philosophic mind, which
would penetrate the deepest depths of nature, without the assistance
of the shaft or ladder of the miner. This is poetry, but not sober
philosophical inquiry.

f The acid from borax.

INORGANIC ORIGIN OF AMMONIA. 123

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, cannot
be detected by our most sensible re-agents; and
nevertheless the many hundred tons annually brought
from Italy as an article of commerce, are procured
by the uninterrupted accumulation of this apparently
inappreciable quantity. The hot steam which issues
from the interior of the earth is allowed to pass
through cold water in the lagoons of Castel Nuova
and Cherchiago ; in this way the boracic acid is
gradually accumulated, till at last it may be ob-
tained 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 con-
verted into borax, many hundred pounds of sulphate
of ammonia are obtained at the same time.

This ammonia has not been produced hy the ani-
mal 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 Saltpetres, 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 distance of from 20 to 30 miles
from the sea.f But it does not require a storm to
cause the volatilization of the salt, for the air hang-
ing over the sea always contains enough of this sub-
stance to make a solution of nitrate of silver turbid,

* See extract from Professor Daubeny's Lectures^ in Appendix,
t Tiiis was observed in the United States after the great storm of
September 23, 1815. See Professor Farrar's account in Mem. A. A. S.

124 OF THE INORGANIC CONSTITUENTS OF PLANTS.

and every breeze must carry this away. Now, as
thousands of tons of sea-water annually evaporate
into the atmosphere, a corresponding quantity of the
salts dissolved in it, viz. of common salt, chloride
of potassium, magnesia, and the remaining constitu-
ents 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 com-
pletely proved at the salt-works of Nauheim, by the
very intelligent director of that establishment, M.
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

* Analyses of sea- water.

Of the British Channel. Of the Mediterranean.

— Schweitzer. — Laurens.
In 1000 parts. — Marcet. Grs. Grs.

Water 964.74372 959.26

Chloride of Sodium 26.660 27.05948 27.22

" of Potassium 1.232 0.76552 0.01

" of Magnesium 5.152 3.66658 6.14

Bromide of Do. 0.02929

Sulphate of Soda 4.660

» of Lime 1.5 1.40662 0.15

" of Magnesia ..... 2.29578 7.02

Carbonate of Lime 0.03301 f ^^^^' ^'"^^ ^"^ I 0.20

^ magnesia. )

According to M*Clemm, the water of the North Sea contains in 1000

parts,

24.84 Chloride of Sodium.

2.42 Chloride of Magnesium.

2.06 Sulphate of Magnesia.

1.35 Chloride of Potassium.

1.20 Sulphate of Lime.
In addition to these constituents, it also contains inappreciable quan-
tities of carbonate of lime, magnesia, iron, manganese, phosphate of
lime, iodides and bromides, silica, sulphuretted hydrogen, and organic
matter, together with ammonia and carbonic acid. (Liebig's Annalen
der Chemie, Bd. xxxvii. s. 3.)

CARBONIC ACID CONTAINED IN SEA-WATER. 125

to the vegetation those salts nacessary to its ex-
istence. This is the origin of the salts found in the
ashes of plants, in those cases where the soil could
not have yielded them.

In a comprehensive view of the phenomena of
nature, we have no scale for that which 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 appears 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^ of its
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 wdth materials for their habita-
tions.

Whilst the air contains only from 4 to 6 ten-thou-
sandth parts of its volume of carbonic acid, sea-
water contains 100 times more, (10,000 volumes of
sea-w^ater 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 exists.

The roots of plants are constantly engaged in
collecting from the rain those alkalies which formed
part of the sea-water, and also those of the water
of springs, which penetrates the soil. Without
alkalies and alkaline bases most plants could not

* 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.

11*

126 THE ART OF CULTURE.

exist, and without^plants the alkalies would disap-
pear gradually from the surface of the earth.

When it is considered, that sea-water contains
less than one-millit)nth 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 surrounding medium.
These plants are collectors of iodine, just as land-
plants are of alkalies ; and they yield us this ele-
ment, 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 f 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.

CHAPTER VII.

THE ART OF CULTURE.

The conditions necessary for the life of all vege-
tables have been considered in the preceding part

* 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.

t Compounds of metals and iodine.

USE OF HUMUS. 127

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
contains a comparatively inexhaustible supply of
carbonic acid and ammonia ; 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
insolubility in cold water of vegetable matter in
progress of decay, (humus,) appears on closer con-
sideration to be a most wise arrangement of nature.
For if humus possessed 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, 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 when
combined with oxygen ; it can be taken up by water,
therefore, only as carbonic acid.

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 deprived of oxygen, the humus suffers
no further change. Its decay proceeds only when
plants grow in the soil containing it; for they ab-
sorb by their roots the carbonic acid as it is formed.
The soil receives again from living plants the car-
bonaceous 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

128 THE ART OF CULTURE.

a fertile arable soil ; the abundant decaying vege-
tables or humus in this soil, being acted on by
moisture and air, constantly 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 caverns, and dis-
solves 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 interior 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 circumstances favorable to the pro-
duction 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 sta-
lactites formed contain no trace of vegetable matter,
and no humic acid ; they are of a glistening white
or yellowish color, and in part transparent, like cal-
careous spar, and may be heated to redness without
becoming black.

The subterranean vaults in the old castles near
the Rhine, the " Bergstrass," and Wetherau, are
constructed of sandstone, granite, or basalt, and
present appearances 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 falling 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 possessed the power of dis-

INSOLUBILITY OF HUMUS. 129

solving a hundred-thousandth part of its own weight
of humic acid or humate 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 absence of the
humic acid of chemists in common vegetable mould.

The common view, which has been adopted re-
specting the modus operandi of humic acid, does
not afford any explanation of the following phenom-
enon: — A very small quantity of humic acid dis-
solved 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 giv-
ing 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
influence upon their vegetation. Water from barren
peat soils and marshy meadows, upon which few
plants flourish, contains much of this humic acid ; but
all agriculturists 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 w^ater 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 complete the decay. The brown
solutions containing this substance are decolorized
in the air by absorbing oxygen, and a black coaly
matter precipitates — the substance named "coal of
humus." Now if a soil were impregnated with this
matter, the effect on the roots of plants w^ould be
the same as that of entirely depriving the soil of
oxygen ; plants would be as little able to grow in
such ground as they would if hydrated protoxide
of iron were mixed with the soil. Indeed, some

130 THE ART OF CULTURE.

barren soils have been found to owe their sterility
to this very cause. The sulphate of protoxide of
iron (copperas), which forms a constituent of these
soils, possesses a powerful affinity for oxygen, and
consequently prevents the absorption of that gas by
the roots of plants in its vicinity. "* All plants die
in soils and water which contain no oxygen; absence
of air acts exactly in the same manner as an excess
of carbonic acid. Stagnant water on a marshy soil
excludes air, but a renewal of water has the same
effect as a renewal of air, because water contains it
in solution. If the w^ater 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 vegeta-
bles do not decay, for they can only do so when
freely supplied with oxygen; but they undergo putre-
faction, for which air is present in sufficient quan-
tity. Putrefaction is known to be a most powerful
deoxidizing process, the influence of which extends
to all surrounding bodies, even to the roots and the
plants themselves. All substances from which oxy-
gen 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
alkaline metallic oxides, the ashes of brown coal,
burnt lime or limestone, change the putrefaction of
its organic constituents into a pure process of oxi-
dation ; and from the moment at which all the or-
ganic 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 most obvious method of removing this salt from soils in which
it may be contained is to manure the land with lime. The lime unites
with the sulphuric acid and liberates the protoxide of iron, which ab-
sorbs oxyg^en with much rapidity, and is converted into the peroxide
of iron. This conversion is accelerated by giving free access to the
air, that is, by loosening the soil.

INSOLUBILITY OF HUMUS. 131

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 Darmstadt, 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 twenty to
twenty-five 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 dis-
tinctly heard at the distance of several feet. Here
the carbonic acid rising to the surface displaces
completely all the air, and consequently all the oxy-
gen, from the soil ; and without oxygen neither seeds
nor roots can be developed; a plant will not vege-
tate in pure nitrogen or carbonic acid gas.*

Humus supplies young plants with nourishment
by the roots, until their leaves are matured sufficient-
ly to act as exterior organs of nutrition ; its quan-
tity heightens the fertility of a soil by yielding more
nourishment in this first period of growth, and con-
sequently 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
commencement of their growth is in a certain mea-
sure injurious.

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 contains. Now, if the quantity of their
stems, leaves, and branches has been increased by

* See note p. 79.

132 THE ART OF CULTURE.

the excess of food yielded by the soil at the com-
mencement of their development, they will require
for the completion of their growth, and for the for-
mation of their blossoms and fruits, more nourish-
ment from the air than it can afford, and consequently
they will not reach maturity. In many cases the
nourishment afforded by the air under these circum-
stances suffices only to complete the formation of
the leaves, stems, and branches. The same result
then ensues as when ornamental plants are trans-
planted 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 em-
ployed 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 leaves
with them, from dwarf trees, since we thus prevent
the development of new branches, an excess of
nutriment is artificially procured for the trees, and
is employed by them in the increase of the blossoms
and enlargement 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 absorb is
employed for the production of nutritive matter for
the following year : instead of woody fibre, starch is
formed, and is diffused through every part of the
plant by the autumnal sap (seve d'Aout).* Ac-

* Hartig, in Erdmann und Schweigger-Seidels Journal, V. 217. 1835.

EXCESS OF NUTRIMENT. 133

cording to the observations of M. Heyer, the starch
thus deposited in the body of the tree can be recog-
nised in its known form by the aid of a good micro-
scope. The barks of several aspens and pine-trees *
contain so much of this substance, 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 forma-
tion of this provision for the following year ; the
wood, as in the case of the vine-stock, 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 its
sugar when its buds, blossoms, and leaves attain
their maturity.

The branch of a willow, which contains a large
quantity of granules of starch in every part of its
woody substance, puts forth both roots and leaves
in pure distilled rain-water; but in proportion as it

* It is well known that bread is made from the bark of pines in
Sweden during famines.

The following directions are given by Professor Autenrieth for pre-
paring a palatable and nutritious bread from the heecU 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 pow-
der ; and after being repeatedly subjected to heat in an oven, is ground
in the usual manner of corn. Wood thus prepared, 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 with-
out 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 pre-
pared 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 y 1827.

134 THE ART OF CULTURE.

grows, the starch disappears, it being evidently ex-
hausted for the formation of the roots and leaves.
In the course of these experiments, M. Heyer made
the interesting observation, 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 distilled 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 ascer-
tained, 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 in-
creased by plucking off the blossoms from the plants
producing them, a result quite consistent with theo-
ry. This important observation has been completely
confirmed by M. Zeller, the director of the Agricul-
tural Society at Darmstadt. In the year 1839, two
fields of the same size, lying side by side and ma-
nured in the same manner, were planted with pota-
toes. 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 pro-
duced 47 bolls, the latter only 37 bolls.

These well-authenticated observations remove ev-
ery doubt as to the part which sugar, starch, and
gum play in the development of plants ; and it ceases
to be enigmatical, why these three substances exer-
cise no influence on the growth or process of nutri-
tion of a matured plant, when supplied to them as
food.

The accumulation of starch in plants during the
autumn has been compared, although certainly erro-
neously, to the fattening of hibernating animals be-
fore 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

EXCESS OF NUTRIMENT. 135

support the process of combustion in the lungs. On
their awaking from their torpor in the spring, the fat
has disappeared, but has not served as nourishment.
It has not caused the least increase in any part of
their body, neither has it changed the quality of any
of their organs. With nutrition, properly so called,
the fat in these animals has not the least connexion.

The annual plants form and collect their future
nourishment in the same way as the perennial ; they
store it in their seeds in the form of vegetable albu-
men, starch and gum, which are used by the germs
for the formation of their leaves and first radicle
fibres. The proper nutrition of the plants, their in-
crease 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
substances which, when presented from without, are
capable 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 constituents.

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
w^e could not conceive 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 an-
other, at all events, if we carry this beyond certain
limits, death is the consequence.

If we could introduce into a tree woody fibre in a
state of solution, it would be the same thing as plac-
ing a potato 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 sub-

136 THE ART OF CULTURE.

stances 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, be-
sides 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 contains within itself the component parts of
the germ and of the radicle fibres, and, we must sup-
pose, 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 capa-
bility 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 forma-
tion of the first part of the roots and leaves ; an ex-
cess of either could not be used in the formation of
leaves, or in any other way.

The conversion of starch into sugar during the
germination of grain is ascribed to a vegetable princi-
ple called diastase, which is generated during the act
of commencing germination. But this mode of trans-
formation can also be effected by gluten, although it
requires a longer time. Seeds, which have germin-
ated, 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 con-
verted into sugar by one part of malted barley.
This excess of diastase can by no means be regarded
as accidental, for, like the starch, it aids in the form-
ation of the first organs of the young plant, and dis-
appears with the sugar ; diastase contains nitrogen
and furnishes the elements of vegetable albumen.

Carbonic acid, water, and ammonia, are the food
of fully-developed plants ; starch, sugar, and gum.

CONDITIONS ESSENTIAL TO NtJTRITION. 137

serve, when accompanied by an azotized substance,
to sustain the embryo, until its first organs of nutri-
tion are unfolded. The nutrition of a foetus and de-
velopment of an egg proceed in a totally different
manner from that of an animal which is separated
from its parent ; the exclusion of air does not en-
danger the life of the foetus, but would certainly
cause the death of the independent animal. In the
same manner, pure water is more advantageous 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 aug-
ments 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
insolubility 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, permeates the wood of the trunk, and con-
verts into sugar the starch, or whatever it may be,
which it finds deposited 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 maybe disposed
of in the same manner as that formed in the trunks ;
at all events it is certain, that the introduction of it
does not prevent the action of the juice upon the
starch, and since the quantity of the sugar present 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 exam-
ple that called honey-dew, evidently depend on tbe
want of the due proportion between the quantity of
the azotized and that of the unazotized substances
which are applied to them as nutriment.

12^

138 THE ART OF CULTURE.

In whatever form, therefore, we supply plants with
those substances which are the products of their
own action, in no instance do they appear to have
any effect 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 matter; 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 which is capable of being transformed into
wood. This substance must be in a state of solution,
and accompanied by a compound containing nitro-
gen ; 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 proportion between them
would be a condition necessary for their production.

According to this view, the assimilation of the
substances generated in the leaves wnll [cceteris
paribus^ depend on the quantity of nitrogen con-
tained 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 sub-
stances 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 other cause.*

'* 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

CONDITIONS ESSENTIAL TO NUTRITION. 139

Analogous phenomena are presented by the pro-
cess of digestion in the human organism. In order
that the loss which every part of the body sustains
by the processes of respiration and perspiration may
be restored to it, the organs of digestion require to
be supplied with food, consisting of substances con-
taining 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 they will
pass unchanged through the organism. This is par-
ticularly 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 assim-
ilation. Potatoes, which when mixed with hay alone
are scarcely capable of supporting the strength of a
horse, form with bread and oats a strong and whole-
some fodder.

It will be evident from the preceding considera-
tions, that the products generated by a plant may
vary exceedingly, 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 accompanied by nitrogen, can-
not be converted either into gluten, albumen, wood,
or any other component part of an organ ; but either
it will be separated in the form of excrements, such
as sugar, starch, oil, wax, resin, mannite,* or gum,
or these substances will be deposited in greater or
less quantity in the wide cells and vessels.

contains sugar. Professor Redtenbacher, of Prague, informs me that
he has analyzed the crystals, and found them to be perfectly pure
sugar. — Ed.

* Mannite forms the greater part of manna. It is found in the
juices of several fruits, in the fermented juice of beet-root, carrots,
onions, &c. ; it is also obtained in small quantity when starch is
transformed into grape sugar by boiling with dilute sulphuric acid.
It crystallizes in prisms, is faintly sweet, soluble in water and hot
alcohol. Its aqueous solution cannot be made to undergo the vinous
fermentation. Its formula is Ce H7 Oe.

140 THE ART OF CULTURE.

The quantity of gluten, vegetable albumen, and
mucilage, 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 nitrogenous substance, or when
we suppress the functions of the leaves by removing
them from the plant.

We know that the ananas is scarcely eatable in
its wild state, and that it shoots forth a great quan-
tity of leaves when treated with rich animal manure,
without the fruit on that account acquiring a large
amount of sugar ; that the quantity of starch in
potatoes increases when the soil contains much
humus, but decreases when the soil is manured with
strong animal manure, although then the number of
cells increases, the potatoes acquiring in the first
case a mealy, in the second ^ soapy, consistence.
Beet-roots taken from a barren, sandy soil contain
a maximum of sugar, and no ammoniacal salts ; and
the Teltowa parsnep loses its mealy state in a
manured land, because there all the circumstances
necessary for the formation of cells are united.*

An abnormal f production of certain component
parts of plants presupposes a power and capability
of assimilation to which the most powerful chemical
action cannot 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 light

* Children fed upon arrow-root, salep, or indeed any kind of amyla-
ceous food, which does not contain ingredients fitted for the formation
of bones and muscles, become fat, and acquire much embonpoint; their
limbs appear full, but they do not acquire strength, nor are their organs
properly developed. — L.

t Abnormal^ (Lat. ab, from, and norma, a rule,) Any thing without,
or contrary to, system or rule. In botany, if a flower has five petals,
the rule is, that it should have the same number of stamens, or some
regular multiple of that number ; if it has only four or six stamens,
the flower is abnormal.

EFFECT OF LIGHT ON CHEMICAL COMBINATION. 141

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 decomposes the car-
bonic 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 diffused
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 sunlight,
but it is not necessary that the direct rays of the
sun reach them. Their functions certainly proceed
with greater intensity and rapidity in sunshine than
in the diffused light of day ; but there is 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.

Thus chlorine * and hydrogen combining form muri-
atic (hydrochloric) acid. This combination is effected
in a few hours in common daylight, but it ensues in-
stantly, 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 gasf of the associated

* Chlorine is a gas named from its green color ; it was formerly
called oxymuriatic acid. It has not been decomposed. It is one of the
most suffocating of the gases, and highly irritating, even when much
diluted with air. It is largely absorbed by water, and the solution has
the properly of bleaching. Its solution in water cannot be kept un-
changed, as the chlorine unites to the hydrogen of the water and
forms muriatic or hydrochloric acid.

Bleaching salts are formed by exposing lime to an atmosphere of
chlorine. Chlorine is useful for removing offensive odors. A few
table spoonfuls of bleaching powder, sprinkled occasionally in privies,
and in larger quantities upon heaps of offensive substances, upon the
floors of slaughter-houses, &-c. will destroy the unpleasant odor, and
at the same time add to the value of the manure.

For description of chlorine, and the method of procuring it, see
Webster's Chemistry^ 3d edit, p 180.

i One of the compounds of hydrogen and carbon.

142 THE ART OF CULTURE.

Dutch chemists with chlorine, is exposed in a vessel
with chlorine 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 re-
quired. When this experiment is performed in the
way first mentioned, two products only are observed
(muriatic acid and perchloride of carbon) ; whilst by
the latter method a class of intermediate bodies are
produced, in which the quantity of chlorine con-
stantly augments, until at last the whole liquid
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 light
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 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 quantity 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 decomposi-
tion of carbonic 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 disappears. Now in these experiments
no nitrogen is supplied at the same time with the car-
bonic acid; hence no other conclusion can be drawn

IMPORTANCE OF AGRICULTURE. 143

from them than that nitrogen is not necessary for
the decomposition of carbonic acid, — for the exer-
cise, therefore, of one of the functions of plants.
And yet the presence of a substance containing this
element appears to be indispensable for the assimila-
tion of the products newly formed by the decompo-
sition of the carbonic acid, and their consequent
adaptation for entering into the composition of the
different 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 plant.
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 excrementitious 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 will vary according to the proportion of the
different kinds of food with which it is supplied.
The development 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 difference which can
be observed being in its height and size, in the num-
ber 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 nitrogenous matters in their food.

The development of the stem, leaves, blossoms,
and fruit of plants is dependent on certain con-
ditions, the knowledge of which enables us to ex-
ercise some influence on their internal constituents

144 THE ART OF CULTURE.

as well as on their size. It is the duty of the natu-
ral philosopher to discover 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 compared in importance
with that of agriculture, for to it belongs the pro-
duction 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 applica-
tion of correct principles is productive of more bene-
ficial effects, or is of greater and more decided in-
fluence. Hence it appears quite unaccountable, that
we may vainly search 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 receive the answer, that they depend upon cir-
cumstances. [Les cir Constances font les assolements.)
No answer could show ignorance more plainly, since
no one has ever yet devoted himself to ascertain
what these circumstances are. Thus also when we
inquire in what manner manure 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 excre-
ments of men and animals are supposed to contain
an incomprehensible something which assists in the
nutrition of plants, and increases their size. This
opinion is embraced without even an attempt 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

* This statement is now somewhat too general; both in this country
and in Great Britain agriculture has received important aid from the
labors of chemists and physiologists.

OBJECT OF AGRICULTURE. 145

peculiar influence on the development of particular
families. These substances either are already con-
tained 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 ma-
nure ? Until these points are satisfactorily deter-
mined, a rational system of agriculture cannot exist.
The power and knowledge of the physiologist, of the
agriculturist and chemist, must be united for the
complete solution of these questions ; and in order
to attain this end, a commencement must be made.

The general object of agriculture is to produce in
the most advantageous manner certain qualities, or
a maximum size, in certain parts or organs of par-
ticular 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 supplying 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 purpose of industry.

The means employed for effecting these two pur-^
poses are very different. Thus the mode of culture^
employed for the purpose of procuring fine pliable
straw for Florentine 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
13

146 THE ART OF CULTURE.

the straw as will enable it to bear the/weight of the
ears.

We must proceed in the culture of plants in pre-
cisely the same manner as we do in the fattening
of animals. The flesh of the stag and roe, or of
wild animals in general, is quite devoid of fat, like
the muscular flesh of the Arab ; or it contains only
small quantities of it. The production of flesh and
fat may be artificially increased; all domestic ani-
mals, 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 perspiration
by preventing motion. The conditions necessary to
effect this purpose in birds are diff"erent 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 ex-
amination of a soil, which is always fertile in given
cosmical and atmospheric conditions ; for it is evi-
dent, that the knowledge of its state and compo-
sition 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 com-
position of a fertile soil, but the discovery of its
proper state or condition belongs to the agricul-
turist ; 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

FERTILITY OF DIFFERENT SOILS- 147

lime, are the names given to the principal constitu-
ents of the different kinds of soil.

Pure sand and pure limestones, in which there are
no other inorganic substances except siliceous earth,
carbonate or silicate of lime, form absolutely barren
soils. But argillaceous earths form always a part
of fertile soils. Now from whence come the argil-
laceous earths in arable land, what are their con-
stituents, and what part do they play in favoring
vegetation ? They are produced by the disintegra-
tion 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 sub-
tances in granite, gneiss, mica-slate, porphyry, clay-
slate, grauw^acke, and the volcanic rocks, basalt, clink-
stone, and lava. In the grauwacke, we have pure
quartz, clay-slate, and lime ; in the sandstones, quartz
and loam. The transition limestone and the dolo-
mites contain an intermixture of clay, felspar, por-
phyry, 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 cal-
caire grossier they exist in greater or less quantity.

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 inva-
riable constituent. There must, therefore, be some-
thing in aluminous earth which enables it to exercise
an influence on the life of plants, and to assist in
their development. The property on which this de-
pends is that of its invariably containing potash and
soda.

Alumina exercises only an indirect influence on
vegetation, by its power of attracting and retaining
water and ammonia ; it is itself very rarely found in

146 THE ART OF CULTURE.

the straw as will enable it to bear the w^eight of the
ears.

We must proceed in the culture of plants in pre-
cisely the same manner as we do in the fattening
of animals. The flesh of the stag and roe, or of
wild animals in general, is quite devoid of fat, like
the muscular flesh of the Arab ; or it contains only
small quantities of it. The production of flesh and
fat may be artificially increased; all domestic ani-
mals, 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 perspiration
by preventing motion. The conditions necessary to
eflfect 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 1 They may easily be detected by the ex-
amination of a soil, which is always fertile in given
cosmical and atmospheric conditions ; for it is evi-
dent, that the knowledge of its state and compo-
sition 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 com-
position of a fertile soil, but the discovery of its
proper state or condition belongs to the agricul-
turist ; 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

FERTILITY OF DIFFERENT SOILS- 147

lime, are the names given to the principal constitu-
ents of the different kinds of soil.

Pure sand and pure limestones, in which there are
no other inorganic substances except siliceous earth,
carbonate or silicate of lime, form absolutely barren
soils. But argillaceous earths form always a part
of fertile soils. Now from whence come the argil-
laceous earths in arable land, what are their con-
stituents, and what part do they play in favoring
vegetation ? They are produced by the disintegra-
tion 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 sub-
tances in granite, gneiss, mica-slate, porphyry, clay-
slate, grauwacke, and the volcanic rocks, basalt, clink-
stone, and lava. In the grauwacke, we have pure
quartz, clay-slate, and lime ; in the sandstones, quartz
and loam. The transition limestone and the dolo-
mites contain an intermixture of clay, felspar, por-
phyry, 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 miischelkalk and the cal-
caire grossier they exist in greater or less quantity.

Alumina exercises only an indirect influence on
vegetation, by its power of attracting and retaining
water and ammonia ; it is itself very rarely found in

150 THE ART OF CULTURE.

kinds of plants grow with the greatest luxuriance.
This fertility is owing to the alkalies which are con-
tained 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 complete ex-
haustion of their alkalies.

We see from the composition of the water in riv-
ers, 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 com-
mon 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
commencement of the development of their germs
and first radicle fibres. Becquerel has shown, that
the graminecB^ leguminoscB, cruciferce, cichoracece, urn-
bellifercBj conifer ce, and ciicurbitacece 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 incineration, 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 Becquerel, in what
manner these alkaline salts enter young plants ; the
acetic acid formed during germination is diffused
through the wet or moist soil, becomes saturated
with lime, magnesia, and alkalies, and is again ab-
sorbed by the radicle fibres in the form of neutral
salts. After the cessation of life, when plants are
subjected to decomposition by means of decay and
putrefaction, 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 porphy-

DISINTEGRATION OF SOILS. 151

ry, and that nothing has vegetated on it for thou-
sands of years. Now this soil would become a mag-
azine of alkalies in a condition favorable for their
assimilation by the roots of plants.

The interesting experiments of Struve have proved
that water impregnated with carbonic acid decom-
poses rocks which contain alkalies, and then dis-
solves ^ part of the alkaline carbonates. It is evi-
dent 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 destroy the coherence of rocks.
Next to the action of air, water, and change of tem-
perature, 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
affect the disintegration of rocks, but from which the
alkalies have not been removed, will be able to afford
the means of nourishment to those vegetables which
require alkalies for their growth during many years ;
but it must gradually become exhausted, unless those
alkalies which have been removed are again replaced ;
a period, therefore, will arrive when it will be neces-
sary to expose it from time to time to a further dis-
integration, in order to obtain a new supply of solu-
ble alkalies. For small as is the quantity of alkali
which plants require, it is nevertheless quite indis-
pensable for their perfect development. 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 ;
harvests 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

152 THE ART OF CULTURE.

produces neither wheat nor tobacco. From every
acre of this land there were removed in the space
of one hundred years 13,200 lbs. of alkalies in
leaves, grain, and straw ; it became unfruitful, there-
fore, 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 culti-
vated land in Europe is in this condition; fallow is
the term applied to land left at rest for further
disintegration. 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 Naples, which is famed for its fruitful corn-
land ; the farms and villages are situated from
eighteen to twenty-four miles distant from one an-
other, 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
removed 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
w^hether humus was ever contained in the soil?

The method of culture in that district completely
explains 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 experiences no change in the two
years during which it there lies fallow, further than
that it is exposed to the influence 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

COMPOSITION OF SOILS. 153

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
fields, therefore, can have gained nothing from the
mere feeding 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 thrive in many parts of Brazil, where
the soils are particularly 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 prematurely? 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 substances
a soil of humus can aiford, since it does not contain
them; the plant may, indeed, under such circum-
stances, become an herb, but will not bear fruit.

Again, how does it happen that wheat does not
flourish 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 quan-
tity, 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

* In consequence of these remarks in the former edition of this
work, Professor Wohler of Gottingen has made several accurate analy-
ses of different kinds of limestone belonging to the secondary and
tertiary formations. He obtained the remarkable result, that all those
limestones, by the disintegration of which soils adapted for the culture
of wheat are formed, invariably contain a certain quantity of potash.
The same observation has also recently been made by M. Kuhlmann
of Lille. The latter observed that the efflorescence on the mortar of
walls consists of the carbonates of soda and potash. — L.

154 THE ART OF CULTURE.

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 calcareous 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 or 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 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 America, on those spots on which forests of pines
which have grown and collected alkalies for centu-
ries, have been burnt, and to which the alkalies are
thus at once restored ; or that the Spartium sco'pari"
um^ Erysimum latifoliumj^ Blitum> capitatum>, Senecio
viscosus, plants remarkable for the quantity of alka-
lies contained in their ashes, should grow with the
greatest luxuriance on the localities of conflagra-
tions ?f

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 stalks of wheat yield

* One thousand parts of the 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 29 parts of ashes, which con-
tain 4-6 parts of soluble salts. (De Saussure.)

t 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 capitatum was seen at Copen-
hagen, the Senecio viscosus in Nassau, and the Spartium scoparium in
Languedoc. After the burnings of forests of pines in North America,
poplars grew on the same soil. — L.

COMPOSITION OF SOILS. 155

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 com-
position.

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 barley and three of oats may be raised.

All plants of the grass kind require silicate of pot-
ash. Now this is conveyed to the soil, or rendered
soluble in it, by the irrigation of meadow^s. The
equisetacecB, the reeds and species of cane, for ex-
ample, which contain such large quantities of silice-
ous earth, or silicate of potash, thrive luxuriantly in
marshes, in argillaceous soils, and in ditches, stream-
lets, and other places where the change of water
renews constantly the supply of dissolved silica.
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 Manheim and Heidel-
berg after a thunder-storm. This mass was at first
supposed to be a meteor, but was found on examina-
tion (by Gmelin) 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
existence 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 sub-
stances 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 con-

* Professor Connall was lately kind enough to show me about half
an ounce of a saline powder, which had been taken from an interstice
in the body of a piece of teak timber. It consisted essentially of phos-

156 THE ART OF CULTURE.

tain certain quantities of phosphates. In the seeds
of different kinds of corn particularly, there is abun-
dance 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 ap-
preciable quantity. Phosphoric acid has been de-
tected also in all mineral waters in which its pres-
ence has been tested; and in those in which it has
not been found it has not been sought for. The
most superficial strata of the deposits of sulphuret
of lead (^galena) contain crystallized phosphate of
lead {^greeyilead ore) ; clay-slate, which forms ex-
tensive strata, is covered in many places with crys-
tals of phosphate of alumina ( Wavellite) ; all its
fractured surfaces are overlaid with it. Phosphate
of lime (^Apatite) is found even in the volcanic
boulders 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 phos-
phorus. 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 ex-
cess is eliminated in the urine and the solid excre-
ments. We may form an idea of the quantity of
phosphate of magnesia contained in grain, when we
consider that the concretions in the csecum of horses

phate of lime, with small quantities of carbonate of lime and phosphate
of magnesia. This powder had been sent to Sir David Brewster from
India, with the assurance that it was the same substance which usually
is found in the hollows of teak timber. It has long been known that
silica, in the form of tabasheer, is secreted by the bamboo ; but I am
not aware that phosphates have been found in the same condition.
Without more precise information, we must therefore suppose that they
are left in the hollows by the decay of the wood. Decay is a slow
process of combustion, and the incombustible ashes must remain after
the organic matter has been consumed. But if this explanation be cor-
rect, the wood of the teak-tree must contain an enormous quantity of
earthy phosphates. — Ed.

* See the analyses of soils in the Appendix.

THE FERTILITY OF SOILS. 157

consist of phosphate of magnesia 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 3*3 lbs. ; and Dr. F. Simon has
lately described a similar concretion found in the
horse of a carrier, which weighed 1'6 lb.

It is evident that the seeds of corn could not be
formed without phosphate of magnesia, which 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 are essential constituents of the plants ordi-
narily cultivated. =^ These other matters, we must
suppose, supply, in part at least, the place and per-
form the functions of the substances just named.
We may thus regard common salt, sulphate of pot-
ash, nitre, chloride of potassium, and other matters,
as necessary constituents of several plants.

Clay-slate contains generally small quantities of
oxide of copper; and soils formed from micaceous
schist contain some metallic fluorides. Now, small
quantities of these substances also are absorbed into
plants, although we cannot affirm that they are
necessary to them.

It appears that in certain cases fluoride of calci-
um t may take the place of the phosphate of lime in the
bones and teeth ;f at least it is impossible otherwise
to explain its constant presence in the bones of

* For more minute information regarding soils see the supplemen-
tary chapter at the end of Part I.

t Fluorine is the base of the acid contained in Fluor or Derbyshire
spar ; with hydrogen it forms the hydrofluoric acid. The acid is separ-
ated by heating fluor spar with sulphuric acid, and is distinguished by
its power of corroding glass, and of uniting with its silica. Compounds
of Fluorine are called Fluorides^ of the acid Hydrofluates. Calcium is
the metallic base of lime.

\ The earthy parts of bones are composed principally of the phos-
phate and carbonate of lime in various proportions, variable in different
animals, and mixed with small quantities, equally variable, of phos-

158 THE ART OF CULTURE.

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 former 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 power-
fully corroded (Liebig) ; whilst the bones and teeth
of animals of the present day contain only traces of
it. (Berzelius.)

De 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 jjgg of ashes a month before
blossoming, ^^§5 while in blossom, and j§§q after the
ripening of the seeds. It is therefore evident, that

phate 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 Berzelius.

Human bone. Ox bone.

Cartilage soluble in water, . . . 32.17 > 33 30

Vessels, . . . . . . . 1*^3 \

Subphosphate, and a little fluate of lime, .

Carbonate of lime, ....

Phosphate of magnesia,

Soda and very little muriate of soda,

100.00 100.00

The bones of man contain three times as much carbonate of lime 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 carbonate
of lime in bones of different animals, according to 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

53.04

11.30

. 1.16

1.20

57.35
3.85
2.05
3.45

FALLOW-CROPS. 159

wheat, from the time of its flowering, restores a part
of its organic constituents to the soil, although 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
progressive disintegration by means of the influence
of the atmosphere, for the purpose of rendering a
certain quantity of alkalies capable of being appro-
priated by plants.

Now, it is evident, that the careful tilling of fal-
low-land must increase and accelerate this disinte-
gration. 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
inclosed in it. Now many plants in the family of
the leguminosce are remarkable on account of the
small quantity of alkalies or salts in general which
they contain; the Windsor bean ( Fzcm Faba), {ov
example, contains no free alkalies, and not one per
cent, of the phosphates of lime and magnesia.
(Einhof.) The bean of the kidney 'he3.n*(^P has eohis
vulgaris) contains only traces of salts. (Braconnot.)
The stem of Lucern (Medicago sativa) contains only
0*83 per cent., that of the Lentil (^Ervum Lens)
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. (Zenneck.)* These plants belong to

* 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.
The following is an analysis of lentils (Playfair). 6-092 grammes lost
0-972 grammes of water at 212°. 0.566 grammes, burned with oxide
of copper, gave 0-910 grammes carbonic acid and 0 336 grammes of
water. The lentils on combustion with oxide of copper, yielded a gas,
in which the proportion of the nitrogen to the carbonic acid was
asl: 16.

Carbon 44 45

Hydrogen 6-59

Nitrogen 642

Water 15 95

160 THE ART OF CULTURE.

those which are termed fallow-crops, and the cause
wherefore they do not exercise any injurious influ-
ence on corn which is cultivated immediately 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 tw^o plants growing beside each
other will mutually injure one another, if they with-
draw the same food from the soil. Hence it is not
surprising that the wild chamomile (^Matricaria
Chamomilla) and Scotch broom (^Spartium Scopa-
rium) impede the growth of corn, when it is con-
sidered that both yield from 7 to 7-43 per cent, of
ashes, which contain ^^ of carbonate of potash. The
darnel and the fleabane (^Erigeron acre) blossom and
bear fruit at the same time as corn, so that when
growing mingled with it, they will partake of the
component parts of the soil, and in proportion to
the vigor of their growth, that of the corn must
decrease ; for what one receives, the others are
deprived of. Plants wdll, on the contrary, thrive
beside each other, either when the substances neces-
sary 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 re-
quires only alkalies, and food containing nitrogen.

According to the analysis of Posselt and Reimann,
10,000 parts of the leaves of the tobacco-plant con-
tain 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 phos-
phates. (De Saussure.)

Now, if we suppose that the grain of wheat is
equal to half the weight of its straw, then the quan-
tity of phosphates extracted from a soil by the same

THE ALTERNATION OF CROPS. 161

weights of wheat and tobacco must be as 97-7: 16.
This difference is very considerable. The roots of
tobacco, as well as those of wheat, extract the phos-
phates 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 ALTERNATION OF CROPS.

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 obtained when a field is allowed
to lie 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, tobacco, helianthus tuberosus, rye, and oats,
may be cultivated in close succession when proper
manure is used. It has also been found, that several
of these plants improve the soil, whilst others, and
these are the most numerous, impoverish or exhaust
it. Fallow turnips, cabbage, beet, spelt, summer
and winter barley, rye and oats, are considered to
belong to the class which impoverish a soil ; whilst
by wheat, hops, madder, late turnips, hemp, poppies,
teasel, flax, weld, and licorice, it is supposed to be
entirely exhausted.

The excrements of man and animals have been
employed from the earliest times for the purpose of
increasing the fertility of soils ; and it is completely

established by all experience, that they restore cer-

14#

162 THE ALTERNATION OF CROPS.

tain 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
always 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 replacement by manure of the substances
removed from the soil, when they are cultivated on
the same field for several 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 gradually 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 con-
stituents of soil, and it was very soon perceived,
that an alternation of the plants cultivated main-
tained the fertility of a soil quite as well as leaving
it at rest or fallow. It was evident, that all plants
must give back to the soil in which they grow differ-
ent proportions of certain substances, which are capa-
ble of being used as food by a succeeding generation.

But agriculture has hitherto never sought aid from
chemical principles, based on the knowledge of those
substances w^hich plants extract from the soil on
which they grow, and of those restored to the soil
by means of manure. The discovery of such prin-
ciples \till 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.

THEORY OF ITS USE. 163

Of all the views which have been adopted regard-
ing the cause of the favorable effects of the alter-
nations of crops, that proposed by M. Decandolle
alone deserves to be mentioned as resting on a firm
basis.

Decandolle 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 subsequently be expelled by the roots, and
returned to the soil as excrements. Now as excre-
ments cannot be assimilated by the plant which eject-
ed them, the more of these matters which the soil
contains, the more unfertile must it be for the plants
of the same species. These excrementitious matters
may, however, still be capable of assimilation by
another kind of plants, which would thus remove
them from the soil, and render it again fertile for
the first. And if the plants last grown also expel
substances from their roots, which can be appropri-
ated as food by the former, they w^ill 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 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 contrary,
that others mutually prevent each other's develop-
ment. Whence it was concluded, that the beneficial
influence in the former case depended on a mutual
interchange of nutriment between the plants, and
the injurious one in the latter on a poisonous action
of the excrements of each on the other respectively.*

* That these supposed exudations are uniformly more or less injuri-

164 THE ALTERNATION OF CROPS.

A series of experiments by Macaire-Princep gave
great weight to this theory. He proved beyond all
doubt, that many plants are capable of emitting ex-
tractive 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 Leguminosce 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 certain quantity of the excrements
of the Leguminosce had really been absorbed 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 different
from one another, and that some plants expel excre-
mentitious matter of an acid and resinous character ;
others mild substances resembling gum. The former
of these, according to Macaire-Princep, may be re-
garded as poisonous, the latter as nutritious.

The experiments of Macaire-Princep afford posi-
tive proof that the roots, probably of all plants, ex-
pel matters, which cannot be converted in their or-
ganism either into woody fibre, starch, vegetable al-
bumen, or gluten, since their expulsion indicates that
they are quite unfitted for this purpose. But they

ous to plants of similar species, has been inferred from the fact, that a
soil, in which peach or apple trees have grown, is unfit for young shoots
of the same description, so as to render it a necessary rule in practice,
that a piece of ground should be occupied by forest and by fruit trees
alternately.

Reference has also been made to a circumstance, which most travel-
lers in the United States have remarked, and which I myself, during
my tour in that country, had frequent opportunities of substantiating,
namely, that where a forest of oak or of maple has been destroyed, the
trees, that are apt to shoot up spontaneously in their place, are of the
fir-tribe ; whereas, if a pine forest be cut down, young oaks and other
allied species will make their appearance afterwards. — Daubeny's
Lectures on Agriculture.

For an account of experiments on this subject now in progress at Ox-
ford, see Appendix.

THEORIES OF ITS USE. 165

cannot be considered as a confirmation of the theory
of Decandolle, for they leave it quite undecided
whether the substances 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 observed by Macaire-Princep
could not have been contained 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 excrements are
compounds, produced in consequence of the trans-
formations of the food, and of the new forms w^hich
it assumes by entering into the composition of the
various organs.

M. Decandolle'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 exactly suited for its assimilation. Ac-
cording 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 ; but they do
not explain how a field is improved by lying 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 cultiva-
tion of certain plants such as lucern and sainfoin.

Theoretical considerations on the process of nutri-
tion, as well as the experience of all agriculturists,
so beautifully illustrated by the experiments of Ma-
caire-Princep, 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 wheth-

166 THE ALTERNATION OF CROPS.

er these excreraents, in the state in which they are
expelled, are capable of being 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 her-
bivorous animal, 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 animal could yield matter
adapted for the nutrition of another.

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 pass-
ing through the digestive apparatus of another ani-
mal. The organs of secretion form combinations of
which only the elements were, contained in the food.
The production of these new compounds is a conse-
quence of the changes which the food undergoes in
becoming chyle and chyme, and of the further trans-
formations to which these are subjected by entering
into the composition of the organism. These mat-
ters, likewise, are eliminated in the excrements,
which must therefore consist of two different kinds
of substances, namely, of the indigestible constitu-
ents 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 substances in any other animal organism.

Exactly similar conditions must subsist in the vi-
tal processes of plants. When substances which are
incapable of being employed in the nutrition of a
plant exist in the matter absorbed by its roots, they
must be again returned to the soil. Such excrements

CAUSES OF ITS BENEFICIAL INFLUENCE. 167

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 w^oody fibre,
starch, albumen, gum, acids, &c., cannot again serve
in any other plants to form the same constituents of
vegetables.

The consideration of these facts enables us to dis-
tinguish the difference between the views of Decan-
dolle and those of Macaire-Princep. The substances
which the former physiologist viewed as excrements,
belonged to the soil ; they were undigested matters,
which although not adapted for the nutrition of one
plant might yet be indispensable to another. Those
matters, on the contrary, designated as excrements
by Macaire-Princep, could only in one form serve for
the nutrition of vegetables. It is scarcely necessary
to remark, that this excrementitious matter must un-
dergo a change before another season. During au-
tumn 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 decay are effect-
ed ; and at the commencement of spring it has be-
come 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 ex-
crements of plants proceeds depends on the com-
position of the soil, and on its greater or less po-
rosity. 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 constituents, 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

168 THE ALTERNATION OF CROPS.

until the fifth or ninth, merely on account of the
change and destruction of the excrements, which
have an injurious influence on the plants being com-
pleted in the one, in the second year; in the others,
not until the ninth.

In some neighborhoods clover will not thrive till
the sixth year, in others not till the twelfth ; flax in
the second or third year. All this depends on the
chemical nature of the soil, for it has been found by
experience, that in those districts where the intervals
at which the same plants can be cultivated with ad-
vantage 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, re-
quire 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 cultivation 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 excrements 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 neighborhood 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 effiects
the most complete and rapid putrefaction of the ex-
crements contained in the soil which it pene-trates,
and in which it is continually renewed. If it was
the water alone which produced this effect, marshy

CULTIVATION OF MEADOWS. 169

meadows should be most fertile. Hence it is not
sufficient in irrigating meadows to convert them into
marshes, by covering for several months their sur-
face with water, w^hich is not renewed; for the
advantage of irrigation consists principally in sup-
plying oxygen to the roots of plants. The quantity
of water necessary for this purpose is very small, so
that it is sufficient to cover the meadow with a very
thin layer, if this be frequently renewed.

The cultivation of meadows forms one of the most
important branches of rural economy. It contributes
materially to the prosperity of the agriculturist by
increasing his stock of cattle, and consequently by
furnishing him with manure, which may be applied
to the augmentation of his crops. Indeed, the great
progress which has been made in Germany in the
improvement of cattle is mainly attributable to the
attention which is devoted in that country to the
culture of meadows. The environs ,of Siegin, in
Nassau, are particulary famed in this respect, and
every year a large number of young farmers repair
to it, for the purpose of studying this branch of
agriculture in situ. In that district the culture of
grass has attained such great perfection, that the
produce of their meadow-land far exceeds that ob-
tained in any other part of Germany. This is effected
simply by preparing the ground in such a manner as
to enable it to be irrigated both in spring and in
autumn. The surface of the soil is fitted to suit the
locality, and the quantity of water which can be
commanded. Thus if the meadows be situated upon
a declivity, banks of from one to two feet in height
are raised at short distances from each other. The
water is admitted by small channels upon the most
elevated bank, and allowed to discharge itself over
the sides in such a manner as to run upon the bank
situated below. The grass grown upon meadow^s
irrigated in this way is three or four times higher
than that obtained from fields which are covered with,
water that is deprived of all egress and renewal,
fe 15

170 , THE ALTERNATION OF CROPS.

It follows from what has preceded, that the ad-
vantage of the alternation of crops is owing to two
causes.

A fertile soil ought to afford to a plant all the in-
organic bodies indispensable for its existence in suf-
ficient quantity and in such condition as allow^s their
absorption.

All plants require alkalies, which are contained in
some, in the GraminecB for example, in the form of
silicates ; 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

* 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 siliceous sinter, and often
incrusting 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 Web-
ster's Description of the Island of St. Michael^ p. 208. From siHca a
substance is obtained which is considered as its base and called silicon
and silicium. 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 white, earthy substance is found be-
neath peat and in swampy lands and ponds, which has long been mis-
taken 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 deposite 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.

CAUSES OF ITS BENEFICIAL INFLUENCE. 171

the formation of the wood takes its origin, actino-
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 Equisetacece and bam-
boos,^ 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 con-
sumes 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 quantities of potash, as
is the case with Leguminosce, turnips, potatoes, &c.,
the wheat may be again sowed with advantage after
the fourth year; for during the interval of three
years the soil will, by the action of the atmosphere,
be rendered capable of again yielding silicate of pot-
ash in sufficient quantity for the young plants.

The same precautions must be observed with re-
gard 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 components 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 containing 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 a
state of carbonic acid. But although this is sufficient
to bring many plants to maturity, it is not enough
to furnish their different organs with the greatest
possible supply of nourishment. Now the object of

* Silica is found in the joints of bamboos, in the form of small round
globules, which have received the name of Tabasheer, and are dis-
tinguished by their remarkable optical properties. — Ed.

172 THE ALTERNATION OF CROPS.

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 car-
bonic acid, contained in the soil in the 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 forma-
tion 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 subsequently growing in it find, at a certain
period of their growth, a maximum of nutriment,
that is, matter in the process of decay.

The same end is obtained, but with much greater
certainty, when the field is planted with sainfoin or
lucern.* These plants are remarkable on account
of the great ramification of their roots, and strong
development 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

* The alternation of crops with sainfoin and lucern is now univer-
sally 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 years after the land has been manured turnips are sown
upon it, in the next following years barley, with sainfoin or lucern ; in
the seventh year potatoes, in the eighth wheat, in the ninth barley;
on the tenth year it is manured, and then the same rotation again takes
place. — L.

CAUSES OF ITS BENEFICIAL INFLUENCE. 173

six-fold surface, capable of assimilating these bodies,
and of preventing the volatilization 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 re-
maining component parts, as well as 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
converted 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 impreg-
nated with excrements, that every fibre of the root
will be surrounded with them. As they remain for
some time in a soluble condition, the plants must
absorb part of them and suffer injurious effects in
consequence, because they are not capable of assim-
ilation. When such a field is observed for several
years, it is seen that the barren spots are again cov-
ered 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 removed, and in their place
meet with humus, that is, vegetable matter in the act
of decay.

We can scarcely suppose a better means of pro-
ducing humus than by the growth of plants, the
leaves of which are food for animals ; for they pre-
pare the soil for plants of every other kind, but
particularly for those to which, as to rape and flax,

15*

174 OF MANURE.

the presence of humus is the most essential condi-
tion of growth.

The reasons why this interchange of crops is so
advantageous, — the principles which regulate this
part of agriculture, are, therefore, the artificial pro-
duction 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 devel-
opment.

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.

CHAPTER IX.

OF 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 principle, it is evident that all the inorganic
constituents of the animal organism must be re-
garded, in some respect or other, as manure. During
their life, the inorganic components of plants which
are not required by the animal system, are disen-
gaged from the organism, in the form of excrements.
After their death, their nitrogen and carbon pass
into the atmosphere as ammonia and carbonic acid,

ANIMAL MANURE. 175

the products of their putrefaction, and at last noth-
ing 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
rational 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.

ANIMAL MANURES.

We may now inquire whether the excrements of
animals, which are employed as manure, are all of
a like nature and power, and whether they, in every
case, administer to the necessities of a plant by an
identical mode of action. These points may easily
be determined 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 pres-
ence of certain compounds of nitrogen, which are
supposed to be assimilated by plants, and employed
in the production of gluten and other azotized sub-
stances. But this view requires further 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 exercise any
influence upon vegetation.

We may form a tolerably correct idea of the chem-
ical nature of the animal excrement without further
examination, by comparing the excrements of a dog
with its food. When a door is fed with flesh and
bones, both of which consist in great part of organic
substances containing nitrogen, a moist white excre-
ment is produced which crumbles gradually to a dry
powder in the air. This excrement consists of the

176 OF MANURE.

phosphate of lime of the bones, and contains scarce-
ly TOO part of its weight of foreign organic substan-
ces. The whole process of nutrition in an animal
consists in the progressive extraction of all the ni-
trogen from the food, so that the quantity 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 excre-
ments 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 un-
der one per cent, cannot be determined with accura-
cy. We should, therefore, be estimating its propor-
tion 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 ox-
ide 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

100000

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 ni-
trogen must have been assimilated. This quantity
of nitrogen entering into the composition of muscu-
lar fibre would yield 8*3 lbs. of flesh in its natural

ITS ESSENTIAL ELEMENTS. 177

condition.* The daily increase in size of a cow is,
however, much less than this quantity. We find that
the nitrogen, apparently deficient, is actually con-
tained in the milk and urine of the animal. The
urine of a milch-cow contains less 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 exer-
cise 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 influence ; 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
vegetation?

When horse-dung is treated with water, a portion
of it to the amount of 3 or 3J per cent, is dissolved,
and the water is colored yellow. The solution is
found to contain phosphate of magnesia, and salts
of soda, besides small quantities of organic matters.f

* 100 lbs. of flesh contain on an average 15-86 of muscular fibre : 18
parts of nitrogen are contained in 100 parts of the latter. — L.

The flesh of animals when digested in repeated portions of cold wa-
ter, affords albumen, saline substances, and coloring and extractive
matters. When the part that is no longer acted on by cold water is di-
gested in hot water, the cellular substance is removed in the form of
gelatine^ and fatty matter separates. The insoluble residue is princi-
pally jtirme.

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.

Nutritive Matter.

Beef, 74

Veal, 75

Mutton, 71

Pork, 76

Chicken, 73

Cod, 79

Haddock, 82

See Brande's

Chemistry J 4 th

edit,

p. 1184.

t Dr. C. T. Jackson

in his '* Geolosn.

cal and .^Agricultural

' Survey of

Rhode Island^'' (page 205,) gives the following analysis

of horse-dung :

178 OF MANURE.

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 soluble 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 76 parts cf water. From the dried excrements,
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 3900 to 4400 lbs. of fresh
horse-dung, corresponding to 110 lbs. of dry dung,
we place on the land from 2737 to 3006 lbs. of wa-
ter, and from 804 to 992 lbs. of vegetable matter and
altered gall, and also from 110 to 297 lbs. of salt
and other inorganic substances.

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

— 500 grains, dried at a heat a little above that of boiling water, lost
357 grains of water. The dry mass weighing 143 grains was burned,
and left 8 grains of ashes, of which 4-81) grains were soluble in dilute
nitric acid, and 320 insoluble. The ashes being analyzed, gave

Silica 3-2

Phosphate of lime 0-4

Carbonate of lime 1'5

Phosphate of magnesia and soda . . 29

80
It consists, then, of the following ingredients : —

Water 3570

Vegetable fibre and animal matter . 1350

Silica 3-2

Phosphate of lime . . . . 0-4

Carbonate of lime 1'5

Phosphate of magnesia and soda , . 2*9

5000

ITS ESSENTIAL ELEMENTS. 179

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 hay.

Thus in 1102 lbs. <jf horse-dung, we present to a
field the inorganic substances contained in 6612 lbs.
of hay, or 9146 lbs. of oats (oats containing 3*1 per
cent, ashes according to De Saussure). This is suf-
ficient to supply 1| crop of wheat with potash and
phosphates.

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 re-
ceives ; the fresh excrements of the cow contain from
86 to 90 per cent, of water.

Human faeces have been subjected to an exact
analysis by Berzelius. When fresh they contain, be-
sides I of their weight of water, nitrogen in very
variable quantity, namely, in the minimum IJ, in the
maximum 5 per cent. In all cases, however, they
were richer in this element than the excrements of
other animals. Berzelius obtained by the incinera-
tion of 100 parts of dried excrements, 15 parts of
ashes, which were principally composed of the phos-
phates of lime and magnesia.

The following quantitative organic analysis has
recently been executed for the purpose of ascertain-

* It has been formerly stated (page 120), that all the potash contained
in the food of a cow is again discharged in its excrements. The same
also takes place with the other inorganic constituents of food, either
when they are not adapted for assimilation, or when present in supera-
bundant quantities. The value of manure may thus be artificially in-
creased. We lately saw, for example, some cow-dung, sent by a farm-
er, who wished to ascertain the cause of its increased value. He had
formerly employed this manure for his land, but with so little advan-
tage that he found it more profitable to dry it, and use it as fuel. On
inquiry, it was found, that his cows had been fed upon oil-cakes. This
species of food is particularly rich in phosphates. More of these salts
being present than were requisite for the purpose of assimilation, they
were removed from the system in the form of excrementitious matter,
and in a condition adapted for the uses of plants. The fact that partic-
ular kinds of food enrich or impoverish the manure obtained from the
cattle fed upon them, has repeatedly been observed. — £d.

180 OF MANURE.

ing the proportion of carbon, nitrogen, and inorganic
matter contained in faeces, in comparison with the
food taken.* (Playfair.)

Carbon 45-24

Hydrogen ....#... 6-88

Nitrogen (average) 4- 00

Oxygen 3030

Ashes 13-58

The inorganic matter contained in the excrements
analyzed is nearly two per cent, less than that found
by Berzelius ; but the proportion always varies, ac-
cording to the nature of the food.

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 carbonic acid to the young plants. But it
cannot be imagined that their influence is very great,
when it is considered that a good soil is manured
only once every six or seven years, or once every
eleven or twelve years,^when sainfoin or lucern has
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 car-
bonic acid than these vegetable constituents of the
manure.

The peculiar action then, of the solid excrements
is limited to their inorganic constituents, which thus
restore 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 potash 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

* The details of the analysis are as follows: — 2-356 grammes left
0320 gramme ashes after incineration ; these consisted of the phosphate
of lime and magnesia. 0352 gramme yielded, on combustion with
oxide of copper7o576 gram, carbonic acid, and 0-218 gram, water.
(L. P.)

ITS ESSENTIAL ELEMENTS- 18 1

of magnesia, and silicate of potash. In the straw
which has served as litter, we add a further quantity
of silicate of potash and phosphates ; which, if the
straw be putrefied, are in exactly the same condition
in which they were before being assimilated.

It is evident, therefore, that the soil of a field will
alter but little, if we collect and distribute the dung
carefully ; a certain portion of the phosphates, how-
ever, must be lost every year, being removed from the
land with the corn and cattle, and this portion will
accumulate in the neighborhood of large towns. The
loss thus suffered must be compensated for in a w^ell-
managed farm, and this is partly done by allowing
the fields to lie in grass. In Germany, it is con-
sidered 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^ 551 lbs. of hay. Now assuming that
the ashes of the excrements of the animals fed with
this hay amount to 6*82 per cent., then 376 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 whichi
the corn-land had sustained.

The absolute loss in the salts of phosphoric acid,,
which are not again replaced, is spread over so great
an extent of surface, that it scarcely deserves to be
taken account of. But the loss of 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
fertility by replacing every year as much as we re-
move from them in the form of produce ; but an in-
crease 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 conditions otherwise similar, the
one will be most fruitful upon which the plants are
enabled to appropriate more easily and in greater
16

182 OF MANURE.

abundance those contents of the soil which are
essential to their growth and development.

From the foregoing remarks it will readily be in-
ferred, that for animal excrements, other subtances
containing their essential constituents may be sub-
stituted. 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 the phosphates of lime and
magnesia. The great importance of manuring with
ashes has been long recognised by agriculturists as
the result of experience. So great a value, indeed,
is attached to this material in the vicinity of Mar-
burg and in the Wetterau,f that it is transported as
a manure from the distance of 18 or 24 miles. J Its
use will be at once perceived, when it is considered
that the ashes, after having been washed with water,
contain silicate of potash exactly in the same pro-
portion as in straw (10 Si 0 3 -(- K 0.), 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 serviceable. 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 exceedingly small quantity of
phosphates, namely, only 1*8 per cent, of phosphoric
acid. (Berthier.) §

* Lixiviation signifies the removal by water of the soluble alkaline or
saline matters in any earthy mixture ; as from that of lime and potash,
or from ashes to obtain a ley.

t Two well known agricultural districts; the first in Hesse-Cassel,
the second in Hesse-Darmstadt. — Trans.

X Ashes are used with great advantage on the light siliceous soil of
Long Island, Connecticut, and various other places in the United
States.

^ " The existence of phosphate of lime in the forest soils of the United
States, is proved not only by its existence in the pollen of the pinus

BONE MANURE. 183

With every 110 lbs. of the lixiviated ashes of the
beech which we spread over a soil, we furnish as
much phosphates as 507 lbs. of fresh human excre-
ments 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 76-5 parts. Now the
ashes of wheat straw contain 11*5 per cent, of the
same salts; hence with every 110 lbs. of the ashes
of the beech, we supply a field with phosphoric acid
sufficient for the production of 4210 lbs. of straw
(its ashes being calculated at 4*3 per cent, De
Saussure), or for 16-20000 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 substances which they take as food. Now
if we admit that bones contain 55 per cent, of the
phosphates of lime and magnesia (Berzelius), and
that hay contains as much of them as wheat strait,
it will follow that 8*8 lbs. of bones contain as much
phosphate of lime as 1102 lbs. of hay or wheat-
straw, and 2-2 lbs. of it as much as 1102 lbs. of the
grain of wheat or oats. These numbers express
pretty nearly 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 44 lbs. of
bone dust is sufficient to supply three crops of wheat,

abies (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. — 10(»
parts of the ashes of wood ofpinus abies give 3 per cent, phosphate of
iron; 100 parts of the ashes of the coal of pinus sylvestris give 1 72
phosphate of lime, 0*25 phosphate of iron ; 100 parts of ashes of oak
coal give 7-1 phosphate of lime, 3-7 phosphate of iron ; 100 parts of the
ashes of bass wood give 5 4 phosphate of lime, 3*2 phosphate of iron ;
100 parts of the ashes of birch wood give 7*3 phosphate of lime, 1-25
phosphate of iron ; 100 parts of the ashes of oak wood give 1-8 phos-
phate of lime ; 100 parts of the ashes of alder coal give 345 phosphate
of lime, 9 phosphate of iron. These are the calculated results from
Berthier's analyses." — Dr. S. L. Dana, in Report on a Reexamination
of the Economical Geology of Massachusetts.

184 OF MANURR

clover, potatoes, turnips, &c., with phosphates. But
the form in which they are restored to 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 the soil,
the more easily are they assimilated. The most easy
and practical mode of effecting 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
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 grau-
wacke, for the purpose of ascertaining the action of
manure thus prepared, have distinctly shown that
neither corn, nor kitchen-garden plants, suffer in-
jurious effects in consequence, but that on the con-
trary they thrive with much more vigor.

It has also been found, that bones act more speed-
ily and efficaciously after being boiled. This is
probably owing to the removal of fatty matter, the
presence of which impedes the putrefaction of the
gelatin contained in them.

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 examine whether this solution might
not be substituted for the bones. The free acid
would combine with the alkalies in the soil, espec-
ially w^ith 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 in dry lands might advan-
tageously supply the place of gypsum in decompos-
ing carbonate of ammonia, with the formation of

EXPLANATION OF ITS ACTION. ' 185

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 neces-
sary 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 f and peat often contain
silicate of potash,{ so that it is evident, that these

* Immense quantities of bran are used in all printworks, for the
purpose of clearing printed goods. After having served this purpose,
it is thrown away. But the insoluble part of bran contains much
phosphates of magnesia and soda; it would therefore be useful to pre-
serve it as a manure. This has been done for some years in a farm
with which I am connected, and its value as a manure has been found
so great that it is much preferred to cow-dung. In some works this
waste bran is heaped up into little hillocks, which might be disposed
of as a manure, instead of being an annoyance on account of the space
which it occupies. — Ed.

t Brown coal. Braunkohle, Lignite has the structure and appearance
of carbonized wood. It occurs abundantly in Germany ; in Hessia it
forms beds 20 to 40 feet thick, and several square miles in 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.

t 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. Burned in a platina crucible
it left 50 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, T-^S

Alumina, oxide of iron, and manganese, . . 15
Phosphate of lime, 1'7

4-5

The vegetable matter amounted to 955 per cent., consisting of veg-
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 vegetable
matters are more finely divided, more soluble, and there is generally 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 and man-

16*

186 OF MANURE.

might completely replace one of the principal con-
stituents 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.

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
mentioned. 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, independently of the influence which
it exerts by virtue of its form, porosity, and capabil-
ity of attracting and retaining moisture, also assists
in maintaining the vital processes in plants. If it
be treated as an unfathomable mystery, the nature
of this aid will never be known.

In medicine, for many centuries, the mode of
action of all remedies was supposed to be concealed
by the mystic veil of Isis, but now these secrets
have been explained in a very simple manner. An
unpoetical hand has pointed out the cause of the
wonderful and apparently inexplicable healing vir-
tues of the springs in Savoy, by which the inhabi-
tants cured their goitre ; it was shown that they
contain small quantities of iodine. In burnt sponges
used for the same purpose, the same element was
also detected. The extraordinary eflicacy of Peru-
vian bark was found to depend on a small quantity
of a crystalline body existing in it, viz. quinine; and
the causes of the various effects of opium were
detected in as many different ingredients of that
drug.

Calico-printers used for a long time the solid
excrements of the cow, in order to brighten and
fasten colors on cotton goods ; this material ap-

ganese ; iron and magnesia occur in several of the peats analyzed.
Phosphoric 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.f 210. See Appendix, for Peat
compost.

EXPLANATION OF ITS ACTION. 187

peared quite indispensable, and its action was as-
cribed 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 mixture of
salts, in which the principal constituents are the
phosphates of soda and lime.*

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 restoration 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 f (silicate of pot-
ash), with the ashes of burnt straw, and with salts
of phosphoric acid, prepared in chemical manufac-
tories, exactly as at present medicines 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

* This mixture of salts is sold to calico-printers in large quantities
under. the name of '« dung substitute." It would be well worth experi-
ment to try its effects as a manure upon land. Its cost is 3d. or 4d. per
pound, and is not, therefore, dearer than nitrate of soda, which is now
so extensively used. — Ed.

t When glass contains a very large proportion of potash, it is soluble
in boiling water ; and by combination with other substances, silica
becomes soluble in water. According to Dr. Jackson, crenic acid
enables water to take it up.

188 ' OF MANURE.

grain, the roots, and the stem, and now proceed to
the consideration of the most important object of
agriculture, viz. the production 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 pro-
portions, but the seeds and roots are always partic-
ularly rich in them.

Let us now examine in what manner the greatest
possible production of substances containing nitro-
gen can be effected. Nature, by means of the atmo-
sphere, furnishes nitrogen to a plant in quantity suffi-
cient for its normal growth. Now its growth must
be considered as normal, when it produces a single
seed capable of reproducing the same plant in the
following year. Such a normal condition would suf-
fice for the existence of plants, and prevent their
extinction, but they do not exist 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 con-
verting, to a certain degree, all the nitrogen offered
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 afforded to it ; a 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 considera-
ble quantity, we enable it to attract with greater en-
ergy from the atmosphere the carbon which is neces-
sary for its nutrition, when that in the soil is not
sufficient ; we afford to it a means of fixing the car-
bon of the atmosphere in its organism.

OF URINE. 189

We cannot ascribe much of the power of the ex-
crements 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 peas-
ants, 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 varia-
ble and relative value. T-hus 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 con-
siderable quantity. In such soils human excrements
are extremely beneficial, and increase their fertility
in a remarkable degree ; they are, of course, as ad-
vantageous for other soils also; but for the manure
of those first mentioned, the excrements of other
animals are quite indispensable.

OF URINE.

We possess only one other natural source of ma-
nure which acts by its nitrogen, besides the faeces
of animals, — namely, the urine of man and animals.

Urine is employed as a 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 property v/hich they themselves possess only in a
very slight degree.

When we examine what substances we add to a

190 OF MANURE.

soil by supplying it with urine, we find that this
liquid contains in solution ammoniacal salts, uric
acid (a substance containing a large quantity of ni-
trogen), and salts of phosphoric acid.

According to Berzelius 1000 parts of human urine
contain : —

Urea . . . 3010

Free Lactic acid,* Lactate of Ammonia, and animal

matter not separable from them . . . 17.14

Uric acid l-OO

Mucus of the bladder 0 32

Sulphate of Potash 371

Sulphate of Soda 3-16

Phosphate of Soda 2 94

Phosphate of Ammonia 1'65

Chloride of Sodium 4*45

Muriate of Ammonia 1-50

Phosphates of Magnesia and Lime ... J-OO

Siliceous earth 0-03

Water 93300

1000-00

If we subtract from tli^ above the urea, lactate of
ammonia, free lactic acid, uric acid, the phosphate
and muriate of ammonia; 1 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 ingredients, namely, the urea and am-
moniacal salts. The urea in human urine exists
partly as lactate of urea, and partl}^ 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 combina-
tion with lactic acid is converted into lactate of am-
monia, and that which was free, into volatile carbon-
ate of ammonia.

In dung-reservoirs well constructed and protected
from evaporation, this carbonate of ammonia is re-
tained in the state of solution, and when the putre-

* Lactic acid has been found in most animal fluids and in several
plants. It was first obtained from sour milk, heiice its name from the
Latin lac J milk.

FIXATION OF AMMONIA. 191

fied urine is spread over the land, a part of the am-
monia will escape with the water which evaporates,
but another portion will be absorbed by the soil, if
it contains either alumina 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 absorbed by
the roots.

On account of the formation of this carbonate of
ammonia 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 employed, so that if we fix it,
that is, if we deprive it of its volatility, we increase
its action twofold. The existence 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 farmer. For
this purpose the liquid obtained from dunghills was
placed in vessels of iron, and subjected to distilla-
tion ; the product of this distillation was converted
into muriate of ammonia by the common method.
(Demachy.) But it is evident that such a thought-
less proceeding must be wholly relinquished, since
the nitrogen of 100 lbs. of sal-ammoniac (which con-
tains 26 parts of nitrogen) is equal to the quantity
of nitrogen contained in 1200 lbs. of the grain of
wheat, 1480 lbs. of that of barley, or 2755 lbs. of
hay. (Boussingault.)

The carbonate of ammonia formed by the putrefac-
tion of urine, can be fixed or deprived of its volatil-
ity in many ways.

If a field be strewed with gypsum, and then with
putrefied urine or the drainings of dunghills, all the
carbonate of ammonia will be converted into the sul-
phate which will remain in the soil.

192 OF MANURE.

But there are still simpler means of effecting this
purpose; — gypsum, chloride of calcium (bleaching
salts), sulphuric or muriatic acid, and super-phos-
phate of lime, are all substances of a very low price,
and completely neutralize the urine, converting its
ammonia into salts which possess 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 below, 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 entirely lost, as far as our
vegetation is concerned, but it 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, — salpe-
terfrass.

The ammonia emitted from stables and necessaries
is always in combination with carbonic acid. Car-
bonate of ammonia and sulphate of lime (gypsum)
cannot be brought together at common temperatures,
without mutual decomposition. The ammonia enters
into combination with the sulphuric acid, and the
carbonic acid with the lime, forming compounds
which are not volatile, 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 ammo-
nia 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

NIGHT-SOIL. 193

by the living organism ; it is soluble in water, and
can be thus absorbed 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
transformations which uric acid suffers in a living
plant. For the purpose of experiment, the plant
should be made to grow in charcoal powder pre-
viously 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 detecting the differences.

NIGHT-SOIL.

In respect to the quantity of nitrogen contained
in excrements, 100 parts of the urine of a healthy
man are equal to 1300 parts of the fresh dung of a
horse, according to the analyses of Macaire and Mar-
cet, 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 in-
valuable by the Chinese, who are the oldest agricul-
tural people we know. Indeed, so much value is
attachied 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, f

* See the article "On the Agriculture of the Netherlands," Journ.
Royal Jigri. Soc.^ Vol. II. part 1, page 43, for much interesting informa-
tion on this subject.

t Davis, in his History of China, states that every substance con-
vertible into manure is diligently husbanded. '* The cakes that remain
after the expression of their vegetable oils, horns and hoofs reduced to
powder, together with soot and ashes, and the contents of common

194 OF MANURE.

China is the birthplace of the experimental art ;
the incessant striving after experiments has con-
sewers, are much used. The plaster of old kitchens, which in China
have no chimneys but an opening at the top, is much valued; so that
they will sometimes put a new plaster on a kitchen for the sake of the
old." The ammonia contained in the fuel forms nitrate of lime with
the lime in the mortar. " All sorts of hair are used as a manure, and
barbers' shavings are carefully appropriated to that purpose. The
annual produce must be considerable 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 some-
times 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 con-
struct large cisterns or pits, lined with lime plaster, as well as earthen
tubs, sunk into the ground, with straw over them to prevent evapora-
tion, in which all kinds of vegetables and animal refuse are collected.
These being diluted with a sufficient quantity of liquid, are left to under-
go the putrefactive fermentation, and then applied to the land. In the
case of every thing except rice, the Chinese seem to manure the plant
itself rather than the soil, supplying it copiously with their liquid
preparation."

"The Chinese husbandman," observes Sir G. Staunton, (Embassy^
Vol. II.,) " 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 the roots of plants and fruit-trees,
the Chinese farmer applies liquid manure likewise."*

Lastly, we extract the following from a communication to Professor
Webster, of Harvard College, United States . — " Human urine, is, if
possible, more husbanded by the Chinese than night-soil for manure ;
every farm, or patch of land for cultivation, has a tank, where all sub-
stances convertible into manure are carefully deposited, the whole
made liquid by adding urine in the proportion required, and invariably
applied in that state." This is exactly the process followed in the
Netherlands : see Outlines of Flemish Husbandry, V^g^ 22.

'• The business of collecting urine and night-soil employs an im-
mense number of persons, who deposit tubs in every house in the cities
for the reception of the urine of the inmates, which vessels are re-
moved daily, with as much care as our farmers remove their honey from
the hives."

When we consider the immense value of night-soil as a manure, it is
quite astounding that so little attention is paid to preserve it. The
quantity is immense which is carried down by the drains in London to
the River Thames, serving no other purpose than to pollute its waters.
It has been shown, by a very simple calculation, that the value of
the manure thus lost amounts annually to several millions of pounds
sterling. A substance, which by its putrefaction generates miasmata,
may, by artificial means, be rendered totally inoffensive, inodorous, and
transportable, and yet prejudice prevents these means being resorted
to. — Ed.

* These statements are confirmed by others, which have been kindly com-
municated to me by a gentleman whose opportunities for observation during
a residence in China of several years, w^ere ample, and whose liberality and
devotion to agriculture and horticulture have already conferred upon the
community results of great interest and value. — See Appendix.

NIGHT-SOIL. 195

ducted the Chinese a thousand years since to dis-
coveries, 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 dis-
covered by them without the assistance of scientific
principles ; for in the books of the Chinese we find
recipes and directions for use, but never explanations
of processes.

Half a century suflSced to Europeans not only to
equal but to surpass the Chinese in the arts and
manufactures, and this was owing merely to the ap-
plication of correct principles deduced from the study
of chemistry. But how infinitely inferior is the agri-
culture of Europe to that of China! The Chinese
are the most admirable 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 experiments
instituted; the quantity of manure consumed 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 IJ lb. daily (| lb.
of urine and J lb. faeces), and that both taken to-
gether contain 3 per cent, of nitrogen, then in one
year they will amount to 647 lbs., w^hich contain
16*41 lbs. of nitrogen, a quantity suflScient to yield
the nitrogen of 800 lbs. of wheat, rye, oats, or of 900
lbs. of barley. (Boussingault.)

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,

196 OF MANURE.

besides containing the most nitrogen, contains also
the most phosphates ; and if rotation 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 dispensed with.

When human excrements are treated in a proper
manner, so as to remove the moisture which they
contain 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.

This is already attempted in many towns, and the
preparation of night-soil for transportation consti-
tutes not an unimportant branch of industry. But
the manner in which this is done is the most in-
judicious 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 car-
bonate of ammonia; lactate and phosphate of am-
monia are also formed, and the vegetable matters
contained in them putrefy ; all their sulphates are
decomposed, whilst 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 evapo-
rates ; 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 before
being dried were neutralized with a cheap mineral
acid.

NIGHT-SOIL. 197

In other manufactories of manure the night-soil,
whilst still soft, is mixed with the ashes of wood, or
with earth,* both of which substances contain a large
quantity of caustic lime, by means of which a com-
plete expulsion of all its ammonia is effected, and it
is 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 preparation of night-soil is now carried on
in London to a considerable extent. Owing to the
variable nature of the climate, artificial means are
employed in its desiccation. The night-soil, after
being subjected to one or other of the modes of
treatment described below, is placed upon iron plates
heated by means of furnaces.

As soon as the night-soil is collected, it is placed
in large broad trenches, until a sufficient quantity is
accumulated for the purposes of the manufacturer.
But here it undergoes the same process of putrefac-
tion to which allusion has been made, and acquires a
peculiarly offensive smell from the evolution of sul-
phuretted hydrogen and other gases, which are
observed to escape. Unless some means be em-
ployed, at this stage of the process, to retain the
ammonia, it escapes into the atmosphere in the form
of a carbonate. Various methods have been proposed
to effect this purpose. Some manufacturers mix the
night-soil with chloride of lime, and evaporate off
the water by the aid of heat. This possesses the
advantage of depriving the excrements of smell,
and at the same time partially fixes the ammonia
which would otherwise escape. Chloride of lime
always contains a considerable excess of lime; hence
part of the ammonia contained in the night-soil is
expelled by means of it.

More simple and economical methods might be
employed. A patent, which has been taken out for

* This is practised in the vicinity of large cities in the United
States.

17*

198 OF MANURE.

the preparation of this useful manure states in its
specification, that the night-soil is to be mixed with
calcined mud and finely-divided charcoal. By this
means, the smell is completely and instantaneously
removed, and the ammonia retained by virtue of the
aflSnity, which alumina and charcoal exert for that
compound. This plan is both simple and efifiicacious,
but the ammonia is apt to be expelled by the appli-
cation of the heat employed in drying the manure.
The addition of a cheap mineral acid to the night-
soil, before admixture with these ingredients, would
materially improve both of the above processes.

It would no doubt be highly advantageous in the
preparation of manures, to prepare them so that
they contained all the ingredients necessary for the
supply of the plants to which they are applied. But
these w^ill of course vary according to the nature of
the soils and plants for which they are intended.
Thus bones, soap-boilers' waste, nitrate of soda,
and ashes of wood, will often be found to form
advantageous additions. Sulphate of magnesia (Ep-
som salts) would, in most cases, form an invaluable
ingredient in prepared night-soil. (See Supplemen-
tary Chapter on Soils.) The products of the decom-
position proceeding from the action of this salt upon
night-soil are, sulphate of ammonia, phosphate of
magnesia, and the double phosphate of magnesia
and ammonia. Now all these salts exert a very
favorable influence upon vegetation, and the phos-
phate of magnesia is, in many cases, perfectly indis-
pensable to the growth and development of certain
plants. This suggestion is well worthy of the
attention of the farmer.

Perhaps the best and most practical method of
fixing the ammoniacal salts of urine and night-soil,
is to mix them with the ashes of peat or coal. When
the latter are employed, care must be taken to select
such as are of a porous, earthy consistence. The
ashes both of peat and coal contain in general mag-
nesia; hence their value as an ingredient of prepared

GUANO. 199

night-soil. When magnesia is not present, it will
be necessary to add some magnesian limestone or
Epsom salts. The night-soil should be mixed thor-
oughly with the ashes, and exposed to the air to
dry. The disagreeable smell is thus quickly removed,
and a pulverulent manure obtained, which can be
applied to the fields with facility.*

Animal charcoal, which has served for the discol-
oration of sugar, possesses the property of removing
the offensive smell of night-soil, and is of itself an
admirable manure. In cases where it can be pro-
cured with facility, it will be found to add to the
efficacy of the latter.f

GUANO.

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. Guano has lately been
imported in considerable quantity into Liverpool and
several other English ports, and is now experi-
mentally employed as a manure by English agricul-
turists. A consideration of its composition and
mode of action cannot, therefore, fail to be accept-
able.

Much speculation has arisen as to the true origin
of Guano, J but the most certain proof is now af-
forded, that it has been produced by the accumula-

* Night soil deprived of its odor and rendered portable is termed
poudrette. One mode of preparing it, practised in France, is by boiling
the refuse matter of slaughter-houses, by steam, into a thick soup ana
then mixing the whole into a stiff paste with sifted coal ashes, and
drying. Tt is almost one half animal matter. If putrefaction should
have begun, the addition of ashes, sweetens the whole, and the pre-
pared "animalized coal," as it is termed, is as sweet to the nose, as
garden mould. — Dana.

t For an account of Mr. Daniell's artificial manure, see Appendix.

I Much of the information regarding Guano here given is extracted
from a paper in Liehig's Mnnalerif xxxvii. 3, 291.

200 OF MANURE.

tion of the excrements of innumerable sea-fowl,
which inhabit the islands upon which it is found.
Meyen, the latest writer upon this subject, completely
coincides with this opinion; for he says* — "Their
number is Legion ; they completely cloud the sun,
when they rise from their resting-place in the morn-
ing in flocks of miles in length." Yet, notwith-
standing their great number, thousands of years
must have elapsed, before the excrements could
have accumulated to such a thickness as they pos-
sess at present. Guano has been used by the Peru-
vians as a manure since the twelfth century; and
its value was considered so inestimable, that the
government of the Incas issued a decree, by which
capital punishment was inflicted upon any person
found destroying the fowl on the Guano islands.
Overseers were also appointed over each province,
for the purpose of insuring them further protection.
Under this state of things, the accumulation of the
excrements may have well taken place. All these
regulations are, however, now abandoned.f Rivero
states, that the annual consumption of guano for the
purposes of agriculture amounts to 40,000 fanegas.
The increase of crops obtained by the use of guano
is very remarkable. According to the same authority,
the crop of potatoes is increased 45 times by means
of it, and that of maize 35 times. The manner of
applying the manure is singular. Thus in Arica,
where so much pepper {^Capsicum haccatum) is cul-
tivated, each plant is manured three times : first
upon the appearance of the roots, second upon that
of the leaves, and lastly upon the formation of the
fruit. (Humboldt.) From this it will be observed,
that the Peruvians follow the plan of the Chinese,
in manuring the plant rather than the soil. The
composition of guano points out how admirably it is
fitted for a manure ; for not only does it contain

* Reise um die Erde, B. i. S. 434.

t Garcilaso, Historic de los YncaSj Vol. I. p. 134.

GUANO. 20 1

ammoniacal salts in abundance, but also those inor-
ganic constituents which are indispensable for the
development of plants.

The most recent analysis is that of Volckel, who
found it to consist of

Urate of Ammonia .... 9*0

Oxalate of Ammonia . . . 10-6

Oxalate of Lime . * . . 7-0

Phosphate of Ammonia . . . 6*0

Phosphate of Magnesia and Ammonia . 2*6

Sulphate of Potash .... 5*5

Sulphate of Soda . . . . 3"8

Sal-ammoniac ..... 4*2

Phosphate of Lime .... 14-3

Clay and sand ..... 4-7
Organic substances not estimated, con-^

taining 12 per cent, of matter insolu- I oo.o

ble in water. Soluble Salts of Iron [

in small quantity. Water . . J

lOO.O

It will be observed from the above analysis, that
urea does not enter into the composition of guano.
The uric acid of the excrements must have been
decomposed into oxalic acid and ammonia. The
soluble substances contained in guano amount to
half its weight. It is singular that we do not find
nitrates amongst the ingredients which compose it.
Guano possesses a urinous smell, precisely similar
to that perceived on the evaporation of urine. The
, experiments upon the efficacy of this manure in
England have not yet been sufficiently multiplied to
enable us to judge whether or not its virtues have
been overrated.

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
considered surprising that where they have once
flourished, they cannot again be expelled by all our
endeavors : we think it very astonishing, while we
really sow them ourselves every year. A famous

202 OF MANURE.

botanist, attached to the Dutch embassy to China,
could scarcely find a single plant on the corn-fields
of the Chinese, except the corn itself. "^

The urine of horses contains less nitrogen and
phosphates than that of man. According to Four-
croy 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
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 concre-
tions 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
excrements 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 to the quantity which we
thus supply, another portion is added from the
atmosphere. The nitrogen 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 nitrogen to be imported
from elsewhere, if it is desired to produce a full
crop. In large farms, the annual expenditure of
nitrogen is completely replaced by means of the
pastures.

The only absolute loss of nitrogen, therefore, is
limited 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

* Ingenhouss on the Nutrition of Plants, page 129 (German edition).

VALUE OF URINE. 203

lost to plants, for it escapes into the atmosphere as
ammonia during the putrefaction and decay of the
body.

A high degree of culture requires an increased
supply of manure. With the abundance of the
manure, the produce in corn and cattle will augment,
but must diminish with its deficiency.

From the preceding remarks it must be evident,
that the greatest value should be attached to the
liquid excrements of man and animals, when a ma-
nure is desired which shall supply nitrogen to the
soil. The greatest part of a superabundant crop,
or, in other words, the increase of growth which is
in our power, can be obtained exclusively by their
means.

When it is considered that with every pound of
ammonia which evaporates a loss of 60 lbs. of corn
is sustained, 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 incomprehensible. In most places only the
solid excrements impregnated with the liquid are
used, and the dunghills containing them are pro-
tected neither from evaporation nor from rain. The
solid excrements contain the insoluble, the liquid all
the soluble phosphates, and the latter contain like-
wise all the potash which existed as organic salts in
the plants consumed by the animals.

Fresh bones, wool, hair, hoofs, and horn, are ma-
nures containing nitrogen as well as phosphates,
and are consequently fit to aid the process of vege-
table life. All animal matter is fitted for the same
purpose. Butchers' offal, such as the blood and
intestines of animals, form a most powerful manure.
It is in general necessary to dilute such manure by
admixture with other kinds less powerful in their
action.

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

204 OF MANURE.

glue, viz., 5'28 per cent., then 100 parts of bones
must be considered 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 into putrefaction; the
gelatine which they contain is decomposed, and its
nitrogen converted into carbonate of ammonia and
other ammoniacal salts, 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.)

ARTIFICIAL MANURES.

We have now examined the action of the animal
or natural manures upon plants ; but it is evident,
that if artificial manures contain the same constitu-
ents, they will exercise a similar action upon the
plants to which they are applied. We shall only
notice here one or two of those principally employed.

Since it has been ascertained that animal manures
act (as far as the formation of organic matter is
concerned) only by the ammonia which they contain,
attention has been devoted by chemists to discover
a more economical means of presenting this ammonia
to plants. The water which distils from the retorts
in the preparation of coal gas is strongly charged
with this alkali, but is at the same time mixed with
tar and other empyreumatic impurities. It has been
customary to allow the tarry matter to subside, and
decant off the clear, supernatant liquor. This liquor,

LIQUOR OF GAS-WORKS. 205

being diluted to such a degree as to be tasteless, is
applied as a manure to the field.*
I Now, the ammoniacal liquor of the gas-works con-
j tains the ammonia in the form of carbonate and
' hydro-sulphate of ammonia (sulphuret of ammonium).
I The latter compound is a deadly poison to vegeta-
I bles, nor can we conceive that by dilution its prop-
erties can be changed. The carbonate of ammonia
is volatile, and escapes into the atmosphere. To
obviate this latter inconvenience and render it more
transportable, it has been proposed to convert the
carbonate into the sulphate, by means of gypsum, f
But this does not remove the hydro-sulphate. A
more simple and efficacious method is to add a solu-
tion of sulphate of iron (the green vitriol of the shops)
to the liquor, until no further precipitation ensues.
Sulphuret and carbonate of iron are thus formed,
and the whole of the ammonia enters into combina-
tion w4th the sulphuric acid, and forms sulphate of
ammonia. Care must be taken to avoid too great an
excess of sulphate of iron ; and the liquor thus pre-
pared should be freely exposed to the air to promote
the oxidation.

The liquor still, however, contains empyreumatic
matters, which are injurious to plants. These may
he removed by evaporating the liquor to dryness,
and heating the residue to incipient redness. By
this means they are rendered insoluble, and the sul-
phate of ammonia is not affected, unless the heat has
been carried too far. The liquor properly diluted
has been found very advantageous, even without the
removal of the empyreumatic matter.

* Mr. Blake, who has charge of the gas- work in Boston, informs me,
that one chaldron (2700 lbs. of Pictou coal, yields, on the average, 33
gallons of ammoniacal liquor containing about 5 per cent, of dry am-
monia ; and by passing the gases generated from this quantity of coal
through a solution of proto-sulphate of iron, he has obtained in addition
24 gallons of a solution containing about 4 per cent, of dry ammonia.
About 4 chaldrons of coal are used per diem, at the gas-works in Boa-
ton, and 200 gallons of liquor, containing from 4 to 5 per cent, of am-
monia, could be furnished daily at small cost. — }V,

t Three Lectures on Agriculture, by Dr. Daubeny, page 87.

206^ OF MANURE.

Nitrate of soda has lately engaged much attention,
and is supposed to exert its favorable action upon
vegetation by yielding nitrogen to those constitu-
ents of plants which contain it. The experiments
which have hitherto been instituted with this ma-
nure do not warrant us in concluding with positive
certainty that it is the nitrogen alone to which it
owes its efficacy, but they certainly render this a
plausible explanation of its virtues. Thus Mr.
Pusey, the late able president of the Royal Agri-
cultural Society, has shown, that the same effects
are produced by putrefied urine, soot, gas-liquor,
and nitrate of soda.* Now the three former act by
virtue of the ammonia which enters into their com-
position. The usual effects produced by these and
nitrate of soda are to increase the intensity of the
green coloring matter, to augment the quantity of
straw, but to produce a light grain. Mr. Hyettf
has communicated the results of an analysis of two
samples of w^heat grown under similar circumstances,
one of which had been treated with nitre, the other
not. The former contained 23*25 per cent, of gluten,
and 1.375 of albumen ; the latter only 19 per cent,
of gluten, and 0.62 of albumen. Here the azotized
matters appear to have considerably increased in
quantity. There is nothing opposed to the sup-
position that nitric acid may be decomposed by
plants, and its nitrogen assimilated. We find that
vegetables possess the power of decomposing car-
bonic acid, and of appropriating its carbon for their
own use. Now this acid is infinitely more difficult
to decompose than nitric acid. But there are other
circumstances which oppose the adoption of the view
that nitrate of soda acts by virtue of the nitrogen
w^hich enters into its composition. Were this the
case, the action should be more uniform than it has
hitherto been found to be. On some soils the salt
does not possess the smallest influence; whilst on

* Journal of the Roval Agricultural Society, Vol. II. p. 123.
i Ibid., Vol. II. p. 143.

NITRATE OF SODA. 207

others it affords great benefit. We can only furnish
an explanation of this seeming caprice by a reference
to the chemical composition of the soil upon which
I it is applied. If the advantages attending the ap-
i plication of nitrate of soda are due to the alkaline
I base which it contains, then it is evident that this
manure can be of small value on soils containing a
quantity of alkalies sufficient for the purposes of the
plants grown upon them; whilst, on the other hand,
such as are deficient in these must experience benefit
through its means.* In certain cases in which ni-
trate of soda has failed, nitrate of potash (common
saltpetre) has been very successful. Analyses of
wheat grown with nitrate of soda and nitrate of pot-
ash would be of interest, in order to determine
whether a mutual substitution of their respective
bases is effected. It is to be hoped that future ex-
periments will throw more light upon the action of
this interesting manure, for theory cannot be satisfied
with those already existing. It has been usual to
employ a less quantity by weight of nitrate of pot-
ash than of nitrate of soda. This procedure seems
rather empirical, for unless sanctioned by experience,
it would a priori appear to be better to add the
greatest quantity of that salt which possesses the
highest equivalent. Now the equivalent of nitrate of
potash is considerably higher than that of nitrate
of soda.

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 argillaceous earth. \

* General Sir Howard Elphinstone informs me, that he found car-
bonate of soda (soda ash) an excellent manure for his land. The crops
obtained by means of it presented the same general characters as those
manured with nitrate of potash, and exhibited a greater intensity of
color. If this is found uniformly to be the case, it will very much
strengthen the supposition that the action of nitrate of soda is due to
its alkaline constituent — Ed.

t For much valuable information on the subject of manures, see
"Agricultural Chemistry," Vol. VIII. of Sir H. Davy's collected
Works.

208 ON THE CHEMICAL CONSTITUENTS OF SOILS.

Ingenhouss proposed dilute sulphuric acid as a
means of increasing the fertility of a soil. Now,
when this acid is sprinkled on calcareous soils, gyp-
sum (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.

SUPPLEMENTARY CHAPTER.

ON THE CHEMICAL CONSTITUENTS OF SOILS.

The fertility of a soil is much influenced by its
physical properties, such as its porosity, color, attrac-
tion for moisture, or state of disintegration. But
independently of these conditions, the fertility de-
pends upon the chemical constituents of which the
soil is composed.

We have already shown, at considerable length,
that those alkalies, earths, and phosphates, which
constitute the ashes of plants, are perfectly indis-
pensable for their development ; and that plants
cannot flourish upon soils from which these com-
pounds are absent. The necessity of alkalies for
the vital processes of plants will be obvious, when
we consider that almost all the different families of
plants are distinguished by containing certain acids,
diff*ering very much in composition ; and further,
that these acids do not exist in the juice in an
isolated state, but generally in combination with
certain alkaline or earthy bases. The juice of the
vine contains tartaric acid, that of the sorrel oxalic
acid. It is quite obvious, that a peculiar action must
be in operation in the organism of the vine and
sorrel, by means of which the generation of tartaric
and oxalic acid is effected ; and also that the same
action must exist in all plants of the same genus.

ON THE CHEMICAL CONSTITUENTS OF SOILS. 209

A similar cause forces corn-plants to extract silicic
acid from the soil. The number of acids found
in different plants is very numerous, but the most
common are those which we have already mentioned;
to which may be added acetic, malic, citric, aconitic,
maleic, kinovic acids, &c.

When we observe that the proper acids of each
family of plants are never absent from it, we must
admit that the plants belonging to that family could
not attain perfection, if the generation of their
peculiar acids were prevented. Hence, if the pro-
duction of tartaric acid in the vine were rendered
impossible, it could not produce grapes, or in other
words, would not fructify. Now the generation of
organic acids is prevented in the vine, and, indeed,
in all plants which yield nourishment to men and
animals, when alkalies are absent from the soil in
which they grow. The organic acids in plants are
very rarely found in a free state ; in general, they
are in combination with potash, soda, lime, or mag-
nesia. Thus, silicic acid is found as silicate of
potash, acetic acid as acetate of potash or soda,
oxalic acid as oxalate of potash, soda, or lime, tar-
taric acid as bitartrate of potash, &c. The potash,
soda, lime, and magnesia in these plants are, there-
fore, as indispensable for their existence as the
carbon from which their organic acids are produced.

In order not to form an erroneous conclusion re-
garding the processes of vegetable nutrition, it must
be admitted that plants require certain salts for the
sustenance of their vital functions, the acids of
which salts exist either in the soil (such as silicic or
phosphoric acids) or are generated from nutriment
derived from the atmosphere. Hence, if these salts
are not contained in the soil, or if the bases neces-
sary for their production be absent, they cannot be
formed; or in other words, plants cannot grow in
such a soil. The juice, fruit, and leaves of a plant
cannot attain maturity, if the constituents necessary
for their formation are wanting, and salts must be

18*

210 ON THE CHEMICAL CONSTITUENTS OF SOILS.

viewed as such. These salts do not, however, occur
simultaneously in all plants. Thus, in saline plants,
soda is the only alkali found ; in corn plants, lime
and potash form constituents. Several contain both
soda and potash, some both potash and lime ; whilst
others contain potash and magnesia. The acids
vary in a similar manner. Thus one plant may
contain phosphate of lime, a second, phosphate of
magnesia, a third, an alkali combined with silicic
acid, and a fourth, an alkali in combination with a
vegetable acid. The respective quantities of the
salts required b}^ plants are very unequal. The
aptitude of a soil to produce one, but not another
kind of plant, is due to the presence of a base w^hich
the former requires, and the absence of that, indis-
pensable for the development of the latter. Upon
the correct knowledge of the bases and salts requi-
site for the sustenance of each plant, and of the
composition of the soil upon which it grows, depends
the whole system of a rational theory of agriculture;
and that knowledge alone can explain the process
of fallow, or furnish us with the most advantageous
methods of affording plants their proper nourish-
ment.

Give, — so says the rational theory, — to one plant
such substances as are necessary for its development,
but spare those, which are not requisite, for the
production of other plants that require them.

It is the same with regard to these bases as it is
with the water which is necessary for the roots of
various plants. Thus, whilst one plant flourishes
luxuriantly in an arid soil, a second requires much
moisture, a third finds necessary this moisture at
the commencement of its development, and a fourth
(such as potatoes) after the appearance of the blos-
som. It would be very erroneous to present the
same quantity of water to all plants indiscriminately.
Yet this obvious principle is lost sight of in the
manuring of plants. An empirical system of agri-
culture has administered the same kind of manures

ON THE CHEMICAL CONSTITXJENTS OF SOILS. 211

to all plants ; or when a selection has been made, it
was not based upon a knowledge of their peculiar
characters or composition.

The cost of labor in England has given rise to
the production of much ingenuity in the invention
of machines, which have produced improvements in
the mode of application of manures. In order to
use these with advantage, pulverulent manures are
employed, instead of the common stable manure,
which is generally mixed with much straw.

The necessity for such forms of manure naturally
suggested the employment of bone dust, dried dung,
lime, ashes, &c. Now, although by these means the
necessary phosphates are furnished to a soil, and
solid animal excrements rendered unnecessary, they
have led to the neglect of the liquid excrements,
that is, of the urine of men and animals, which is
thus completely lost to agriculture. For although
the meadows receive, during autumn and winter,
when cattle are fed upon them, the solid and liquid
excrements of these animals, yet the urine of man,
into which all the nitrogenous constituents of ani-
mals are finally deposited, is completely lost to the
fields. This most important of all manures, so pro-
perly estimated in Flanders, Germany, and China, is
altogether lost to the English agriculturist. In large
towns it is either allowed to run into the rivers, or
sink into the ground in such a manner as to be of no
benefit to the vegetable kingdom.

The most important growth in England is that of
wheat ; then of barley, oats, beans, and turnips. Po-
tatoes are only cultivated to a great extent in certain
localities ; rye, beet-root, and rape-seed, not very
generally. Lucern is only known in a few districts,
whilst red clover is found universally. Now, the se-
lection of inorganic manures for these plants may be
fixed upon by an examination of the composition of
their ashes. Thus wheat must be cultivated in a soil
rich in silicate of potash. If this soil is formed from
feldspar, mica, basalt, clinkstone, or indeed of any

212 ON THE CHEMICAL CONSTITUENTS OF SOILS.

minerals which disintegrate with facility, crops of
wheat and barley may be grown upon it for many
centuries in succession. But, in order to support an
uninterrupted succession, the annual disintegration
must be sufficiently great to render soluble a quanti-
ty of silicate of potash sufficient for the supply of a
full crop of wheat or barley. If this is not the case,
the soil must either be allowed to lie fallow from
time to time, or plants may be cultivated upon it
which contain little silicate of potash, or the roots
of which are enabled to penetrate deeper into the
soil than corn plants in search of this salt. During
this interval of repose, the materials of the soil dis-
integrate, and potash in a soluble state is liberated
on the layers exposed to the action of the atmo-
sphere. When this has taken place, rich crops of
wheat may be again expected.

The alkaline phosphates, as well as the phosphates
of magnesia and lime, are necessary for the produc-
tion of all corn-plants. Now, bones contain the latter,
but none of the former salts. These must, therefore,
be furnished by means of night-soil, or of urine, a
manure which is particularly rich in them.* Wood
ashes have been found very useful for wheat in cal-
careous soils ; for these ashes contain both phos-
phate of lime and silicate of potash. In like man-
ner stable manure and night-soil render clayey soils
fertile, by furnishing the magnesia in which they are
deficient. The ashes of all kinds of herbs and de-
cayed straw are capable of replacing wood ashes.

A compost manure, which is adapted to furnish all
the inorganic matters to wheat, oats, and barley, may
be made, by mixing equal parts of bone dust and a
solution of silicate of potash (known as soluble glass
in commerce), allowing this mixture to dry in the
air, and then adding 10 or 12 parts of gypsum, with
16 parts of common salt. Such a compost would

* It has been already stated that bran contains phosphate of soda and
phosphate of magnesia, so that it is useful as a manure where phos-
phates are desired. — Ed.

ON THE CHEMICAL CONSTITUENTS OF SOILS. 213

render unnecessary the animal manures, which act
by their inorganic ingredients. According to Ber-
thier, 100 parts of the ashes of wheat straw con-
tain, —

Of matter soluble in water 9*0

Of matter insoluble in water . . . . 91-0

Now 100 parts of the soluble matter contain, —

Carbonic acid ...... a trace

Sulphuric acid 20

Muriatic acid 130

Silica . 350

Potash and Soda 500

1000

100 parts of the insoluble matter contain, —

Carbonic acid . . . . .0

Phosphoric acid . . . . .1*2

Silica . 75 0

Lime ...... 5-8

Oxide of Iron and Charcoal .... 10-0

Potash ...... 8-0

100-0

The silicate of potash employed in the preparation
of the compost described above must not deliquesce
on exposure to the air, but must give a gelatinous
consistence to the water in which it is dissolved, and
dry to a w^hite powder by exposure. It is only at-
tractive of moisture when an excess of potash is
present, which is apt to exert an injurious influence
upon the tender roots of plants. In those cases
where silicate of potash cannot be procured, a suffi-
ciency of wood ashes will supply its place.*

All culinary vegetables, but particularly the cruci-

* In some parts of the grand duchy of Hesse, where wood is scarce
and dear, it is customary for the common people to club together and
build baking ovens, which are heated with straw instead of wood. The
ashes of this straw are carefully collected and sold every year at very
high prices. The farmers there have found by experience that the
ashes of straw form the very best manure for wheat; although it exerts
no influence on the growth of fallow-crops (potatoes or the leguminosaB,
for example). The stem of whe?t grown in this way possesses an un-
common strength. The cause of the favorable action of these ashes
will be apparent, when it is considered that all corn plants require sili-
cate of potash ; and that the ashes of straw consist almost entirely of
this compound. — Ed.

214 ON THE CHEMICAL CONSTITUENTS OF SOILS.

ferae, such as mustard, (^sinapis alba and nigra,) con-
tain sulphur in notable quantity. The same is the
case with turnips, the different varieties of rape, cab-
bage, celery, and red clover. These plants thrive
best in soils containing sulphates ; hence if these
salts do not form natural constituents of the soil,
they must be introduced as manure. Sulphate of
ammonia is the best salt for this purpose. It is most
easily procured by the addition of gypsum or sul-
phate of iron ^ (green vitriol) to putrefied urine.

Horn, wool, and hoofs of cattle, contain sulphur
as a constituent, so that they will be found a valua-
ble manure when administered with soluble phos-
phates, (with urine, for example.)

Phosphate of magnesia and ammonia forms the
principal inorganic constituent of the potato ; salts
of potash also exist in it, but in very limited quanti-
ty. Now the soil is rendered unfitted for its culti-
vation, even though the herb be returned to it after
the removal of the crop, unless some means are
adopted to replace the phosphate of magnesia re-
moved in the bulbous roots. This is best effected
by mixtures of night-soil with bran, magnesian lime-
stone, or the ashes of certain kinds of coal. I ap-
plied to a field of potatoes manure, consisting of
night-soil and sulphate of magnesia (Epsom salts),
and obtained a remarkably large crop. The manure
was prepared by adding a quantity of sulphate of
magnesia to a mixture of urine and faeces, and mix-
ing the whole with the ashes of coal or vegetable
mould, till it acquired the consistence of a thick
paste, which was thus dried by exposure to the sun.

It has been formerly mentioned, that the seconda-
ry and tertiary limestones contain potash : marl, and
the calcareous minerals used for the preparation of
hydraulic mortar, may be particularly specified.

* If sulphate of iron be employed, it ought not to be added in great
excess, and the urine must be exposed to the air for some time after,
for the purpose of converting the iron into the peroxide. A salt of the
protoxide of iron is injurious to vegetation. — Ed.

ON THE CHEMICAL CONSTITUENTS OF SOILS. 215

These have been found to form excellent manures
for heavy clayey soils, particularly for such as disin-
tegrate with difficulty. They are most efficacious
when burnt, but can only be applied in this state
after harvest, and ought to be ploughed into the soil
as quickly as possible. By the action of lime upon
clay, the potash contained in the latter is rendered
soluble. This may easily be shown by mixing one
part of marl with half its weight of burned lime,
adding water, and setting aside the mixture to re-
pose for some time. Even after a space of 24 hours,
an appreciable quantity of potash may be detected
in the water.*

A most striking proof of the influence of potash
upon vegetation has been furnished by the investi-
gations of the " administration " of tobacco in Paris.
For many years accurate analyses of the ashes of
various sorts of tobacco have been executed, by the
orders of the " administration " ; and it has been
found, as the result of these, that the value of the
tobacco stands in a certain relation to the quantity
of potash contained in the ashes. By this means a
mode was furnished of distinguishing the different
soils upon which the tobacco under examination had
been cultivated, as well as the peculiar class to
which it belonged. Another striking fact was also
disclosed through these analyses. Certain cele-
brated kinds of American tobacco were found gradu-
ally to yield a smaller quantity of ashes, and their
value diminished in the same proportion. For this
information I am indebted to M. Pelouze, professor
of the Polytechnic School in Paris.

* One of the causes of the advantages produced by subsoil ploughing
is, that it exposes the soil to the disintegrating influences of the atmo-
sphere. Hence it is that the subsoil plough is so beneficial in siliceous
soils, and exerts no apparent effect upon those which contain much
clay. The former disintegrate and liberate their potash both with fa-
cility and rapidity ; whilst the disintegration of the latter proceeds with
slowness, and no appreciable effects are produced. (See Journal of the
Agricultural Society, Vol. II. p. 27.) It is probable, however, that if
the land received a dressing of lime after subsoil ploughing, the effects
would be produced more rapidly. — Ed.

216 ON THE CHEMICAL CONSTITUENTS OF SOILS.

There are certain plants which contain either no
potash, or mere traces of it. Such are the poppy,
(^papaver somniferum,) which generates in its organ-
ism a vegetable alkaloid; Indian corn (^zea mays)]
and helianthus tuherosus. For plants such as these
the potash in the soil is of no use, and farmers are
well aw^are that they can be cultivated without ro-
tation on the same soil, particularly when the herbs
and straw, or their ashes, are returned to the soil
after the reaping of the crop.

One cause of the favorable action of the nitrates
of soda and potash must doubtless be, that through
their agency the akalies which are deficient in a soil
are furnished to it. Thus it has been found that in
soils deficient in potash, the nitrates of soda or pot-
ash have been very advantageous ; whilst those, on
the other hand, w^hich contain a sufficiency of alka-
lies, have experienced no beneficial effects through
their means. In the application of manures to soils
we should be guided by the general composition of
the ashes of plants, whilst the manure applied to a
particular plant ought to be selected with reference
to the substances which it demands for its nourish-
ment. In general, a manure should contain a large
quantity of alkaline salts, a considerable proportion
of phosphate of magnesia, and a smaller proportion
of phosphate of lime; azotized manure and ammonia-
cal salts cannot be too frequently employed.

In the following part of this chapter I shall de-
scribe a number of analyses of soils executed by
Sprengel, together with observations on their sterili-
ty and fertility, as stated by that distinguished
agriculturist. It is unnecessary to describe the mo-
dus operandi used in the analyses of these soils, for
this kind of research will never be made by farmers,
who must apply to the professional chemist, if they
wish for information regarding the composition of
their soils.

Under the term surface-soil, we mean that portion
of soil w^hich is on the surface ; whilst by subsoil we

ON THE CHEMICAL CONSTITUENTS OF SOILS. 217

mean that which is below the former, and out of
reach of the ordinary plough.

CHEMICAL COMPOSITION OF CERTAIN SOILS, ACCORDING TO

ANALYSIS.

1. Surface-soil (A) a good loamy soil, from the
vicinity of Gandersheim. It is remarkable for pro-
ducing uncommonly fine red clover when manured
with gypsum. (B) is an analysis of the subsoil.
100 parts contain : —

(A) (B)

Silica, with fine siliceous sand . . 91-331 93883

Alumina 1-344 1-944

Peroxide of iron, with a little protoxide 1-562 2 226

Peroxide of manganese . . . 0*082 0*320
Magnesia and silica, in combination with

sulphuric acid and humus . . . 0*800 0 720
Magnesia, with silica and humic acid

combined . . . . . 0*440 0*340

Potash, in combination with silica . 0*156 0*105
Soda, principally in combination with

silica, and a little as common salt . 0*066 0*060

Phosphoric acid 0*098 01 90

Sulphuric acid in combination with lime 0111 0*012

Chlorine (in common salt) . . 0012 0*012

Humus, with traces of azotized matter . 4100 0*184

100000 100*000

An inspection of the above analyses will show
that the soil contains a very small proportion of salts
of sulphuric acid, — a circumstance which accounts
for the favorable action of gypsum upon it.

2. The surface-soil (A) is a fine-grained loamy
soil from Gandersheim, distinguished for the re-
markably large crops of beans, peas, tares, &c.,
which it produces when manured with gypsum. (B)
is the analysis of the subsoil. 100 parts contain: —

(A) (B)

Silica, with fine siliceous sand . . 90*221 92-324"

Alumina 2106 2 262

Peroxide and protoxide of iron . . 3951 2 914
Peroxide of manganese . . . 0-960 2*960
Lime, principally combined with phos-
phoric acid and humus . . . 0 539 0-532

218

ON THE CHEMICAL CONSTITUENTS OF SOILS.

Magnesia, with silicate of potash, &c. . 0-730

Potash 0-066

Soda 0-010

Phosphoric acid 0*367

Sulphuric acid (in gypsum) . . • a trace

Chlorine (in common salt) . . 0*100

Humus and azotized matter . . . 0900

Loss 0-140

(B)
0-340
0-304
a trace
0-122
0-010
0004

0-228

100-000 100000

The analysis of this soil shows, that, with the ex-
ception of gypsum, every ingredient is present
which is requisite for the nourishment of leguminous
plants. Hence it is that gypsum exerts such a
favorable influence upon it.

3. Surface-soil (A) a strong loamy sand,
Brunswick. (B) the analysis of the subsoil,
parts contain : —

from
100

Silica, with coarse siliceous sand .
Alumina .....

Peroxide and protoxide of iron

Peroxide of manganese

Lime ......

Magnesia ....

Potash and soda, the greatest part in

combination with silica
Phosphate of iron
Sulphuric acid (in gypsum) .
Chlorine (in common salt)
Humus

(A)

95-698
0-504
2-496

a trace
0038
0-147

0-090
0-164
0007
0-010
0-846

(B)

96-880
0-890
1-496

a trace
0019
0-260

0-079

0110

a trace

0-226

100000 100000

This soil was much improved by manuring with
lime and ashes. It was then found well fitted for
clover, beans, and peas.

4. Surface-soil (A) a loamy sand, from the envi-
rons of Brunswick. (B) analysis of the subsoil at
the depth of 3 feet. 100 parts contain : —

(A) (B)
Silica and fine siliceous sand . . 94-724 97 340
Alumina . . . . 1-638 0-806
Protoxide and peroxide of iron with man-
ganese ..... 1-960 1201

Lime 1-028 0-296

Magnesia .... a trace 0095

Potash and soda . . . 0-077 0-112

Phosphoric acid .... 0024 0-015

Gypsum .... 0.010 a trace

ON THE CHEMICAL CONSTITUENTS OF SOILS.

219

Chlorine of the salt
Humus

(A)
0-207
0-512

(B)
a trace

0135

100-000 100-000

This soil produces luxuriant crops of lucern and
sainfoin, as well as of all other plants the roots of
which penetrate deeply into the ground. The rea-
son is apparent. The subsoil contains magnesia,
which is wanting in the surface-soil.

5. Surface-soil (A) a loamy sand, from the envi-
rons of Brunswick. (B) analysis of the subsoil at a
depth of 2 feet. 100 parts contain : —

Silica, with coarse siliceous sand

Alumina

Protoxide and peroxide of iron .

Peroxide of manganese

Lime, in combination with silica

Magnesia in do. do.

Potash and soda .

Phosphate of iron

Sulphuric acid . . ' .

Chlorine

Humus soluble in alkalies

Humus insoluble in alkalies .

(A)

(B)

. 95-843

95-180

0600

1-600

. 1-800

2-200

a trace

. 0-038

0-455

0-006

0-160

. 0-005

0004

0198

0400

. 0-002

a trace

0-006

0001

. 1-000

• . •

0-502

. . .

100-000

This soil is characterized by its great sterility.
White clover could not be made to grow upon it.
The obvious cause of its poverty is a deficiency of
lime, magnesia, potash, and gypsum ; for we find
that the fertility of the soil was much increased by
manuring it with marl. The white clover, which
formerly had refused to grow on this soil, now grew
upon it with much luxuriance. The aridity of the
soil could not have been the cause of its sterility,
for the stiff nature of the subsoil on which it rested
prevented a deficiency of moisture.

6. Surface-soil (A) a loamy land from the environs
of Brunswick. (B) the analysis of the subsoil, at a
depth of 2 feet. 100 parts contain : —

(A)

(B)

Silica, with fine siliceous sand .

. 94-998

96-490

Alumina

0-61O

1-083

Protoxide and peroxide of iron .

. 1 080

1-472

220 ON THE CHEMICAL CONSTITUENTS OF SOILS.

(A)

(B)

Peroxide of manganese

0-268

0-400

Lime, in combination with silica

. 0-141

0-182

Magnesia, idem

0-208

0-205

Potash, idem

. 0050

0-070

Soda, idem

0044

0-050

Phosphate of iron

. 0086

0-030

Gypsum

0041

0005

Common salt

. 0-004

0-003

Humus soluble in alkalies

0-400

0010

Humus accompanied by azotized matter

2070

• • •

Resinous matter

•

a trace

• • •

100000

This soil is by no means remarkable for its steril-
ity, but is decidedly improved by manuring with
burned ferruginous loam. It is, however, rendered
still better by the use of burned marl, — a manure
which is rich in iron, potash, gypsum, and phosphate
of lime. The marl does not exert so favorable an
action when applied in its natural state ; but the heat
liberates the potash from the insoluble compound
which it forms with silica.

7. Surface-soil (A) a loamy sand, from Brunswick.
(B) analysis of the subsoil at a depth of IJ feet. 100
parts contain : —

Silica, with fine siliceous sand .

Alumina ....

Protoxide and peroxide of iron .

Peroxide of manganese

Lime, combined with silica

Magnesia, idem

Potash, idem

Soda, idem ....

Phosphate of iron

Sulphuric acid contained in gypsum

Chlorine ....

Humus soluble in alkalies

Humus, with azotized organic remains

(A)

(B)

. 92-980

96-414

0-820

1-000

. 1-666

1-370

0-188

0-240

, 0748

0-364

0-168

0160

, 0-065

0045

0-130

0082

. 0246

0043

a trace

0-005

a trace

0-007

0764

0-270

2225

. . .

100-000

This soil when manured with gypsum is very fa-
vorable to the production of leguminous plants and
red clover. But it is very remarkable, on account of
the rust which always attacks the corn p]E;*nts which
may be grown upon it. This rust and mildew (uredo
linearis, jpucdnia graminis) is a disease which at-

ON THE CHEMICAL CONSTITUENTS OF SOILS.

221

tacks the stem and leaves, and is quite different from
the brand {uredo glumarum) which appears on the
seeds and organs of reproduction. Rust is most fre-
quently detected on plants growing on soils which
contain bog-ore, or turf iron-ore. According to
Sprengel, rust contains phosphate of iron, to which
this chemist ascribes the origin of the disease. It
is very possible that other causes may operate in the
production of similar diseases.

8. Soil, a fine-grained loamy marl, from the vicin-
ity of Schoningen. It produces corn, which is, how-
ever, very liable to blight. 100 parts contain : —

Silica, with siliceous sand .

. .

. 93'870

Alumina

. .

1-248

Protoxide and peroxide of iron

. 1-418

Peroxide of manganese .

. •

0-360

Lime (principally carbonate)

• •

. 0-546

Magnesia, idem .

• .

0-560

Potash, with silica .

. •

. 0-050

Soda, with silica

. •

0-040

Phosphate of iron

« 4

. 0-246

Sulphuric acid with lime

. .

0-027

Carbonic acid, with lime and

magnesia

. 1-145

Humus soluble in alkalies

• .

0-400

Humus

•

. 0-090

100-000

It will be observed that a considerable quantity of
phosphate of iron is contained in this soil, and the
corn which grows upon it is, as in the former case,
disposed to rust.

9. Surface-soil (A) a loamy soil, from Brunswick,
remarkable on account of producing buck-wheat,
which is exceedingly poor in the grain. (B) analy-
sis of the subsoil at a depth of IJ foot. 100 parts
contain: —

Silica, with coarse siliceous sand

Alumina ....

Protoxide and peroxide of iron .

Protoxide and peroxide of manganese

Lime, in combination with silica

Magnesia, idem

Potash, with silica .

Soda .....

Phosphate of iron

Sulphuric acid with lime

19*

(A)

(B)

95-114

92-458

1080

2-530

1-900

2502

0-320

0-920

0380

0-710

0-300

0-551

0020

0120

0004

0-034

0052

0175

0-006

a trace

222

ON THE CHEMICAL CONSTITUENTS OF SOILS.

Chlorine (in common salt)
Humus soluble in alkalies
Humus

(A)
0.005
0-619
0-200

(B)
a trace

100-000 100000

By manuring the land with wood ashes, the soil is
enabled to produce buck-wheat, with rich grain ; the
leguminous plants also thrive luxuriantly upon it.
This increased fertility is due to the ashes, by means
of which both potash and phosphates are supplied to
the land.

10. Subsoil of a loamy, sandy soil, from Brunswick.
•It is remarkable for having produced excellent crops
of hops for a long series of years. 100 parts, by
weight, consist of: —

Silica, with siliceous sand ,

95-660

Alumina . . • .

. 1-586

Protoxide and peroxide of iron

1-616

Peroxide of manganese . ,

. 0-240

Lime, in combination with silica

0083

Magnesia . . . •

. 0080

Potash ....

0030

Soda . . . . .

. 0-220

Phosphoric acid . • •

0039

Sulphuric acid . • . •

. 0-003

Chlorine ....

a trace

Humus soluble in alkalies

. 0-080

Humus ....

0-360

100000

Although the hops contain a large quantity of
potash, soda, phosphoric acid, sulphuric acid, lime,
and magnesia, yet we do not find that these exist
in the soil in superabundant quantity. Nor is it
necessary that they should, for the roots of the hops
penetrate 8 or 10 feet deep into the soil, and search
out the materials jfitted to nourish the plants. Hence
it is that hops thrive well on soils comparatively
poor in their proper ingredients. The same is the
case with all plants of a similar nature, the roots of
which possess a tendency to extend in search of
food; we see this particularly in lucern and sainfoin.

ON THE CHEMICAL CONSTITUENTS OF SOILS. 223

SOILS OF HEATHS.

11. Soil of a heath converted into arable land, in
the vicinity of Brunswick. It is naturally sterile,
but produces good crops when manured with lime,
marl, cow-dung, or the ashes of the heaths which
grow upon it.

Silica, and coarse siliceous sand . . 71*504
Alumina ..... 0*780
Protoxide and peroxide of iron, principally com-
bined with humus . . . 0*420
Peroxide of manganese, idem . . . 0*220
Lime, idem .... 0*1 34
Magnesia, idem ..... 0032
Potash and soda principally as silicates . 0*058
Phosphoric acid, (principally as phosphate of iron) 0*115
Sulphuric acid (in gypsum) , . . 0*018
Chlorine (in common salt) . . , 0014
Humus soluble in alkalies . , . 9"820
Humus, with vegetable remains . . 14*975
Resinous matters .... 1*910

100000

Ashes of the soil of the heath, before being con-
verted into arable land: —

Silica, with siliceous sand . . . 92*641
Alumina ..... 1*352
Oxides of iron and manganese . . 3.324
Lime, in combination with sulphuric and phos-
phoric acids ..... 0*929
Magnesia, combined with sulphuric acid . 0*283
Potash and soda (principally as sulphates and

phosphates) ..... 0*564

Phosphoric acid, combined with lime . 0250

Sulphuric acid, with potash, soda, and lime . 1*620

Chlorine in common salt . . . 0*037

100.000

12. Surface-soil of a fine-grained loam, from the
vicinity of Brunswick. It is remarkable from the
circumstance, that not a single year passes in which
corn plants are cultivated upon it without the stem
of the plants being attacked by rust. Even the
grain is covered with a yellow rust, and is much
shrunk. 100 parts of the soil contain: —

Silica and fine siliceous sand . . 87 859

Alumina ..... 2652

Peroxide of iron with a large proportion of protoxide 5* 132

224 ON THE CHEMICAL CONSTITUENTS OF SOILS.

Protoxide and peroxide of manganese . 0*840

Lime principally combined with silica . . 1*459

Magnesia idem .... 0*280

Potash and soda idem .... 0*090

Phosphoric acid in combination with iron . 0*505

Sulphuric acid in combination with lime . 0*068

Chlorine in common salt , . . 0*006

Humus ...... 1*109

100-000

This soil does not suffer from want of drainage :
it is well exposed to the sun, is in an elevated situa-
tion, and in a good state of cultivation. In order
to ascertain whether the rust was due to the con-
stituents of the soil, (phosphate of iron ?) or to cer-
• tain fortuitous circumstances unconnected with their
operation, a portion of the land was removed to
another locality, and made into an artificial soil of
fifteen inches in depth. Upon this barley and wheat
were sown ; but it was found, as in the former case,
that the plants were attacked by rust, whilst barley
growing on the land surrounding this soil was not
at all affected by the disease. From this experiment
it follows, that certain constituents in the soil favor
the development of rust.

13. Soil of a heath, which had been brought into
cultivation in the vicinity of Brunswick. The analy-
sis was made before any kind of crops had been
grown upon it. Corn-plants were first reared upon
the new soil, but were found to be attacked by rust,
even on those parts which had been manured respec-
tively with lime, marl, potash, wood ashes, bone-dust,
ashes of the heath plant, common salt, and ammonia.
100 parts contain : —

Silica with coarse siliceous sand . . 51.337

Alumina . . . . . 0528
Protoxide and peroxide of iron in combination

with phosphoric and humic acids . . 0*398

Protoxide and peroxide of manganese . . 0 005

Lime in combination with humus . . 0230

Magnesia idem . . . ' . . 0-040

Potash and soda . . . . 0*010

Phosphoric acid . . . . . 0066

Sulphuric acid .... 0*022

Chlorine . . . . . 0*014

Humus soluble in alkalies . . . 13*210

ON THE CHEMICAL CONSTITUENTS OF SOILS. 225

Resinous matters .... 2-040

Coal of humus and water . . . 32- 100

100000

The next analysis represents the soil after being
burnt. 100 parts by weight of the soil left after
ignition only 60 parts. 100 parts of these ashes
consisted of: —

Silica and siliceous sand . . . 95-204

Alumina ..... 1*640

Peroxide of iron .... 1 -344

Peroxide of manganese .... 0*080

Lime in combination with sulphuric acid . 0-544

Magnesia combined with silica . . 0*465

Potash and soda .... 0052

Phosphoric acid (principally as phosphate of iron) 0*330

Sulphuric acid .... 0322

Chlorine . .... 0019

100*000
By comparing this analysis with the one which
has preceded it, an increase in certain of the con-
stituents is observed, particularly with respect to
the sulphuric acid, potash, soda, magnesia, oxide of
iron, oxide of manganese, and alumina. From this
it follows, that the humus, or in other words, the
vegetable remains, must have contained a quantity
of these substances confined within it, in such a
manner that they were not exhibited by analysis.

Oats and barley were sown on this land the
second year after being reclaimed, and both suffered
much from rust, although different parts of the soil
were manured with marl, lime, and peat-ashes ; whilst
other portions were left without manure. In the
first year, all the different parts of the field pro-
duced potatoes, but they succeeded best in those
divisions which had been manured with peat-ashes,
lime and marl. In the second year, oats mixed with
a little barley were sown upon the soil; and the
straw was found to be strongest on the parts treated
with peat-ashes, lime, marl, and ashes of wood. Red
clover was sown on the third year ; it appeared in
best condition on those portions of the soil manured
with marl and lime. Upon the divisions of the field

226 ON THE CHEMICAL CONSTITUENTS OF SOILS.

which had been left without manure, as well as on
those manured with bone-dust, potash, ammonia, and
common salt, the clover scarcely appeared above
ground. The divisions of the field, which had been
manured in the first year with peat-ashes, ammonia,
and ashes of wood, were sown with buckwheat after
the removal of the first crop of clover. The buck-
wheat succeeded very well on all the divisions, yet
a marked difference was perceptible in favor of the
portion treated with ammonia. These experiments
show us, that a dressing of lime did not completely
remove from the soil its tendency to impart rust to
the plants grown upon it. Nevertheless it is highly
probable, that as soon as the protoxide of iron
became converted into the peroxide by exposure to
the atmosphere, lime would possess more power in
decomposing the phosphate of iron.

14. Subsoil of a loamy soil in the vicinity of
Brunswick. It is remarkable from the circumstance
that sainfoin cannot be cultivated upon it more than
two or three years in succession. The portion
analyzed was taken from a depth of five feet. 100
parts contained : —

Silica with very fine siliceous sand

90-035

Alumina

•

. 1-976

Peroxide of iron

4700

Protoxide of iron

•

, 1115

Protoxide and peroxide of manganese

0-240

Lime ....

■

. 0-022

Magnesia ....

0-115

Potash and soda

•

. 0-300

Phosphoric acid, combined with iron .

0098

Sulphuric acid (the greatest part in combina

tion

with protoxide of iron)

1-399

Chlorine

•

. a trace

100000

Now the results of the analysis give a sufficient
account of the failure of the sainfoin. The soil
contains above one per cent, of sulphate of the pro-
toxide of iron (^green vitriol of commerce), a salt
which exerts a poisonous action upon plants. Lime
is not present in quantity sufficient to decompose

ON THE CHEMICAL CONSTITUENTS OF SOILS. 227

this salt. Hence it is that sainfoin will not thrive
on this soil, nor indeed lucern, or any other of the
plants with deep roots. The evil cannot be obviated
by any methods sufficiently economical for the far-
mer, because the soil cannot be mixed with lime at a
depth of five or six feet. For many years experi-
ments have been made in vain, in order to adapt this
soil for sainfoin and lucern, and much expense in-
curred, which could all have been saved, had the
soil been previously analyzed. This example affords
a most convincing proof of the importance of chemi-
cal knowledge to an agriculturist.

15. Surface-soil (A) of a sandy loam in the vicini-
ty of Brunswick, celebrated for its beautiful crops
of clover, rye, potatoes, and barley. The clover
must, however, always be manured with gypsum.
(B) is an analysis of the subsoil at the depth of 1|
foot. 100 parts contain : —

(A) (B)

Silica with coarse siliceous sand . . 94-274 95146

Alumina 1-560 1-416

Peroxide of iron with a little phosphoric acid 2*496 2-528

Peroxide of manganese .... 0*240 0320

Lime 0*400 0 297

Magnesia 0-230 0 221

Potash and soda . . . . . 0102 0 060

Sulphuric acid 0*039 0-012

Chlorine 0-005 a trace

Humus soluble in alkaline carbonates . 0-444 . . .

Humus 0-210 . . .

100000 100-000

The best property of this soil is, that its inferior
layers are nearly of the same composition as the
superior, as far as the inorganic constituents are
concerned. It is a soil upon which the plants
mentioned above will seldom fail ; and as it posses-
ses a very good mixture to the depth of four or five
feet, it would, doubtless, produce lucern also.

16. Surface-soil (A) of a sandy loam in the vicinity
of Brunswick. It produces excellent crops of oats
and clover, when the latter is manured with gypsum.

228

ON THE CHEMICAL CONSTITUENTS OF SOILS.

(B) Analysis of the subsoil taken from a depth of
1| foot. 100 parts contain : —

Silica and siliceous sand

Alumina .....

Peroxide of iron with a little phosphoric acid

Peroxide of manganese

Lime, principally combined with silica

Magnesia, idem ....

Potash .....

Soda .....

Sulphuric acid ....

Chlorine .....

Humus .....

(A)

(B)

94-430

89-660

1.474

0980

2-370

7-616

a trace

0-680

0954

0-290

0-520

0190>
0010 s

0150

a trace

0015

a trace

0-541

0120

100-000

Both the surface and the sub-soil contain only
traces of sulphuric acid. Hence the application of
gypsum is attended with great benefit. Without
doubt, marl and lime will be found of essential
service.

17. Soil from the environs of Brunswick, consisting
principally of sand, and eminently remarked for its
sterility. It was, however, much improved by ma-
nuring it with marl which contained 24 per cent, of
lime, together with magnesia, manganese, potash,
soda, gypsum, and common salt. 100 parts of the
soil contained : —

Silica and siliceous sand . .

. 95-841

Alumina ....

0-600

Protoxide and peroxide of iron

. 1800

Peroxide of manganese

a trace

Lime in combination with silica .

. 0 038

Magnesia, idem

0006

Potash .....

. 0-002

Soda .....

0-003

Phosphoric acid combined with iron

. 0198

Sulphuric acid

0-002

Chlorine .....

. 0006

Humus . . .

1-504

100 000

Here another proof is presented, that a soil may
be very rich in humus and yet be very poor as re-
gards fertility. By means of the marl, the inorganic
ingredients of the plants are furnished to the soil,
which contains them in very small quantity.

ON THE CHEMICAL CONSTITUENTS OF SOILS. 229

18. The soil of a very fertile loam from the vicin-
ity of Walkenried. 100 parts contain: —

Silica, with coarse-grained siliceous sand . 88-456

Alumina ...... 0-650

Peroxide and protoxide of iron, accompanied by much

magnetic iron sand .... 5-608

• Peroxide of manganese . . . . 0*560

Carbonate of lime ..... 1-063

Carbonate of magnesia .... 1'688

Potash combined with silica . . . 0*040

Soda combined with silica . . . 0*012

Phosphate of lime ..... 0035

Sulphate of lime . . . . . a trace

Common salt . . . . .0 005

Humus soluble in alkalies . . . 0-550

Humus with several azotized organic remains . 1*333

100*000

Gypsum acts most excellently upon this land.
The soils in the southern range of the Harz moun-
tains are particularly remarked for containing more
magnesia than lime. Even the different varieties
of marl contain a considerable quantity of magnesia.
Thus in a specimen of marl obtained from the vi-
cinity of Walkenried, I obtained 65J per cent, car-
bonate of lime, and 30^ per cent, carbonate of mag-
nesia; in another 41 per cent, lime, and 11 per cent,
magnesia; and in a third, 47| per cent, lime, and
13J per cent, magnesia. Most of these soils contain
also J, — 1 per cent, of gypsum, and |, — 1 per cent,
phosphate of lime, and are, therefore, well fitted for
manuring other lands.

19. Subsoil of a loam from a depth of IJ foot. It
occurs in the vicinity of Brunswick. The surface-
soil is remarkable on account of producing beautiful
red clover on being manured with gypsum ; although
the soil itself contains only traces of lime, magnesia,
potash, and phosphoric acid. 100 parts of the sub-
soil contained : —

Silica and coarse siliceous sand . . . 88-980

Alumina . . . . . 2-240

Protoxide and peroxide of iron . . • 3-840

Peroxide of manganese . , , a trace

Carbonate of lime .... 2720

Carbonate of magnesia . . • 0*600

Potash and soda ..... 0095

230

ON THE CHEMICAL CONSTITUENTS OF SOILS.

Phosphate of lime
Sulphate of lime
Common salt

1-510

a trace

0015

100-000

At a greater depth than the subsoil of which the
analysis is here given, the soil passes into marl,
which contains 20| per cent, of carbonate of lime.
The sulphuric acid deficient in the soil was supplied
by means of the gypsum.

SOILS IN THE KINGDOM OF HANOVER.

20. (A) Analysis of a barren heath-soil from
Aurich in Ostfriesland ; (B) a sandy soil containing
much humus but also sterile; (C) a sandy soil
possessing the same characters as B. 100 parts
contained : —

(A)

(C)

Silica and coarse siliceous sand

. 95-778

85-973

96 721

Alumina

0 320

0-320

0-370

Protoxide and peroxide of iron

. 0-400

0440

0-480

Peroxide of manganese

a trace

Lime

. 0-286

0160

0005

Magnesia

0060

0-240

0080

Soda .....

. 0036

0012

0.036

Potash . .

a trace

Phosphoric acid

. a trace

a trace

Sulphuric acid ....

a trace

Chlorine in common salt

. 0052

0-019

0058

Humus

0768

4-636

0800

Vegetable remains

. 2-300

8-200

1-450

100-000 100-000 100000
21. Analysis of the clayey subsoil of a moor,
which, after being burned, is used as a manure to
the above soils A, B, C. 100 parts contain : —

Silica and siliceous sand . . . 87*219

Alumina . . . . . , 4*200

Peroxide of iron with a little phosphoric acid . 5.200

Peroxide of manganese . . . 0-310

Lime ...... 0-320

Magnesia ...... 0380

Potash principally combined with silica . 0-130

Soda principally combined with silica . . 0*274
Sulphuric acid combined with lime, magnesia, and

potash . . ... 0-965

Chlorine ..... 0-002

Humus . . . . . . 1000

100-000

ON THE CHEMICAL CONSTITUENTS OF SOILS. 231

By comparing this analysis with that of the three
soils which have preceded, it will be observed that
this subsoil is fitted to impart to them those mineral
ingredients in which they are deficient.

22, Surface soil of a barren heath in the vicinity
of Walsrode in Luneberg. 100 parts by weight
contain : —

Silica and siliceous sand .... 92*216

Alumina ..... 0*266

Peroxide of iron . • . . . 0*942

Protoxide of iron .... 0*394

Peroxide of manganese .... a trace

Lime, in combination with silica, sulphuric acid,

and humus ..... 1*653

Magnesia, in combination with silica . . 0036

Potash, principally in combination with silica 0038

Soda . . . . . .a trace

Phosphoric acid . ... .a trace

Sulphuric acid ..... 0*051

Chlorine . . . . .a trace

Humus, soluble in alkaline carbonates . . 2 084

Humus ...... ]-900

Resinous matter ..... 0*420

100000

This soil contains a large quantity of protoxide of
iron, which, together with a deficiency of phosphoric
acid, is the cause of its sterility. But when this
land was manured with the ashes of peat, it was
rendered much more fertile. The ashes used for this
purpose were found to contain in 100 parts : —

Silica, with siliceous sand . . . 96*352

Alumina ..... 1*859

Peroxide and protoxide of iron, with a little phos-
phoric acid ..... 1*120

Peroxide of manganese . . . 0*160

Lime . . . . . .0*112

Magnesia ..... 0*141

Potash ...... 0-093

Soda ...... 0007

Sulphuric acid . ' . , . . 0*152

Chlorine ..... 0*004

100000

The ashes, on exposure to the air, absorbed am-

monia.

23. Analysis of a very fertile loamy soil from Got-
tingen. It is very rich in humus, and produces beau-

232

ON THE CHEMICAL CONSTITUENTS OF SOILS.

tiful crops of peas, beans, lucern, and beet. The
sieve separates from 100 parts of the soil : —

Small stones, principally limestone . . I

Quartzy sand, with a little magnetic iron sand . 15

Earthy part . . . . . .84

100

100 parts of the soil, freed from stones, consists
of: —

Silica, and fine siliceous sand . . . 83*298

Alumina, combined with silica . . 1 413

Alumina, partly in combination with humus . 3'715
Peroxide and protoxide of iron, in combination

with silica ..... 0*724
Peroxide and protoxide of iron, partly free and

partly in combination with humus . . 2 244

Peroxide and protoxide of manganese . 0*280
Lime, with coal of humus, sulphur, and phosphoric

acid ...... 1-814

Magnesia, combined with silica . . 0-422

Magnesia, combined with humus . • . 0*400

Potash ...... 0003

Soda . .... 0001

Phosphoric acid .... 0166

Sulphuric acid . . • . . 0-069

Chlorine ...... 0-002

Carbonic acid (as carbonate of lime) . . 0440

Humus, soluble in alkalies . . . 0789

Humus, with a little water . . . 3'250

Nitrogenous matter . . . . 0-960

Resinous matter . . . . .a trace

100000

The subsoil is of the same composition as the sur-
face, with this difference only, that it contains more
potash, soda, and chlorine,* and is interspersed with
fragments of fresh-water shells. Hence it is that
the soil produces the deep-rooted plants in such lux-
uriance.

24. Soil of a sterile moor, which had been burned
three times, and upon which buckwheat had been
cultivated. 100 parts contained : —

Humus, soluble in alkalies . . . 9-250

Vegetable remains, charcoal, quartzy sand, and

earthy particles . . . . . 90-750

100000

* The portion of the surface-soil subjected to analysis was taken from
the field after long-continued rain. Hence the small quantity of salts
of potash and soda.

ON THE CHEMICAL CONSTITUENTS OF SOILS.

233

100 parts by weight left, after ignition, 10 parts

ashes. 100 parts of these ashes consisted of:

Silica and siliceous sand .... 79*600
Alumina
Peroxide of iron
Peroxide of manganese

Carbonate of lime

Carbonate of magnesia

Potash

Soda

Phosphoric acid

Sulphate of lime (gypsum)

Chlorine

6-288
. 0-857

0-400
. 7-652

1-640
. 0080

0-028
. 0-215

3235
. 0-005

100000

Soils such as this, after having been burned seve-
ral times, and made to produce buckwheat, are com-
pletely deprived of their potash and soda ; and in
consequence of this are rendered quite barren. Hence
it is that ashes of wood exert such an astonishing
effect upon them.

25. Analysis of a very fertile loamy sand, from
Osnabriick, near Rotherifeld. It is remarkable for
being manured only once every 10 or 12 years, and
bears beautiful wheat as the last crop. 100 parts
contain : —

Silica, with coarse siliceous sand .

•

86-200

Alumina ....

•

2000

Peroxide and protoxide of iron, with a little

phos-

phoric acid ....

2-900

Peroxide of manganese

0100

Carbonic acid, and a little phosphate of lime

4-160

Carbonate of magnesia

0-520

Potash and soda

0035

Phosphoric acid ....

0-020

Sulphuric acid ....

•

0021

Chlorine .....

0010

Humus, soluble in alkaline carbonates

0 544

Humus .....

3-370

Nitrogenous matter

0-120

100000

The soil in question lies on the southern exposure
of a hill, which consists of layers of limestone and
marl. The rain-water penetrates through these lay-
ers, and becomes saturated with the soluble salts
contained in them, such as potash, gypsum, common
salt, lime, magnesia, and saltpetre. It afterwards

20*

234 ON THE CHEMICAL CONSTITUENTS OF SOILS.

reaches the soil, and manures it with these ingredi-
ents. It is only in this manner that we are enabled
to explain the fertility of this soil ; for, reasoning
from its chemical composition, we should be induced,
a priori, to suppose that it would be barren. At the
base of this hill, certain portions of the land are
covered with calcareous tuff, containing the above
salts : a fact which proves that the water which pen-
etrates through the soil must also contain them in
solution. The large proportion of humus exhibited
by the analysis depends upon the nature of the ma-
nure with which it was treated.

26. Analysis of a heavy alluvial soil, from Norden.
100 parts contain: —

Silica, and very fine siliceous sand . , 84*543

Alumina

Peroxide of iron

Peroxide of manganese

Lime

Magnesia .

Potash ....

Soda, in combination with silica

Phosphoric acid, in combination with lime

Sulphuric acid ...

Chlorine . . .

Humus, soluble in alkalies

3-458
3-488
0-560
0-319
0-740
a trace
6-004
0-260
0-008
0-008
0-416

Hutnus and nitrogenous matter . . 0-196

100000

The portion of the soil subjected to analysis was
taken at a depth of 10 inches, from a field which
had received no manure for several years. It had
previously produced in succession barley, beans,
wheat, and grass, the latter for two years. The soil
is remarkable, in a chemical point of view, from the
large quantity of soda which it contains. Although
the sulphuric acid, chlorine, and potash, are present
in small quantity, yet this does not present any bar-
rier to the development of the plants, as the surface-
soil is 18 inches in depth.

27. Analysis of a heavy alluvial soil in the vicinity
of Norden. 100 parts contain; —

Silica, and very fine siliceous sand . . 79*174

Alumina ..... 3016

ON THE CHEMICAL CONSTITUENTS OF SOILS.

235

Peroxide of iron . .

4-960

Peroxide of manganese

. 0-600

Carbonate of lime

2-171

Carbonate of magnesia

. 2226

Potash, in combination with silica

0025

Soda, idem

. 6-349

Phosphoric acid

0-534

Sulphuric acid . . , ,

. a trace

Chlorine ....

0005

Humus, soluble in alkalies

. 0-782

Humus, with nitrogenous matter

0-158

100.000

The specimen for analysis was taken at a depth
of 10 inches from the surface of a field, which had
been manured five years previously, and had pro-
duced since that time rape, rye, wheat, and beans.
The crops of all these were plentiful, and of excel-
lent quality. It is singular that this soil, which
contains such a small proportion of gypsum, should
be adapted for the cultivation of beans, and must
be ascribed to the depth of the surface-soil. Yet,
notwithstanding this, gypsum would form a beneficial
manure to the land.

28. Analysis of very fertile alluvial* soil, from
Honigpolder; no manure had ever been applied to
it. 100 parts contain: —

Siliceous sand separated by the sieve . . 4*5

Earthy portion of the soil

100 parts of the latter consisted of: —

Silica, and fine siliceous sand

Alumina ....

Peroxide of iron ....

Peroxide of manganese

Lime . . • . .

Magnesia ....

Potash, principally in combination with silica

Soda, idem . . .

Phosphoric acid combined with lime .

Sulphuric acid, idem

Chlorine (in common salt) . . .

Carbonic acid, combined with lime

Humus soluble in alkalies

Humus ....

Nitrogenous matter ....

Water .....

95-5
1000

64-800
5.700
6-100
0090
5-880
0-840
0-210
0393
0-430
0-210
0-201
3-920
2-540
5-600
1-582
1504

100000

236

ON THE CHEMICAL CONSTITUENTS OF SOILS.

Corn has been cultivated for seventy years upon
this soil, v^hich has never received dung or any other
kind of manure; it is, how^ever, occasionally fallowed.
The subsoil retains the same composition as the
surface-soil for a depth of 6-12 feet, so that it may
be considered inexhaustible. When one portion of
the soil is rendered unfit for use, the inferior layers
are brought up to the surface.

29. Analysis of a soil from Rahdingen, near Balje.
In this case the sea has assisted in the formation of
the soil. The field yielded beautiful corn after being
manured with stable dung, being particularly re-
marked for its fine crops of v^heat, beans, and winter
barley. 100 parts contain: —

Silica, siliceous sand, and silicates

Alumina

Peroxide of iron

Peroxide of manganese

Lime . . . •

Magnesia

Potash and soda soluble in water

Phosphoric acid

Sulphuric acid

Chlorine (in common salt)

Humus, soluble in alkaline carbonates

Humus

Nitrogenous matter

Water

87012
4-941
2-430
0192
0-292
0145
0-005
0114
0074
0003
0-658
2-668
1-412
0042

100-000

30. Soil of a field remarkable for producing large
crops of hemp and horse-radish. 100 parts con-
sisted of: —

Silica and siliceous sand

Alumina

Peroxide of iron

Peroxide of manganese

Lime

Magnesia

Potash

Soda

Phosphoric acid •

Sulphuric acid

Chlorine

Humus, soluble in alkaline carbonates

Humus and nitrogenous matter .

84-021
4-498
5120
2-080
0942
1-740
0-050
0-012
0-482
0012
0-008
0-897
0138

100000

ON THE CHEMICAL CONSTITUENTS OF SOILS.

237

31. Surface-soil of a field near Drackenburg ; it
produces very bad red clover. 100 parts contain: —

Silica, with very fine siliceous sand . . 92-014

Alumina . . . • . 2*652
Peroxide of iron .... 3*192

Peroxide of manganese . . . 0-480

Lime . . . • . . 0*243

Magnesia ..... 0-700

Potash combined with silica . . .0*125

Soda, idem ..... 0-026

Phosphoric acid, in combination with lime . 0*078

Sulphuric acid .... a trace

Chlorine . . . . .a trace

Humus and nitrogenous matter . 0*150

Humus, soluble in alkaline carbonates . . 0*340 •

100-000

The cause that clover will not flourish on this soil
is probably due to the deficiency of gypsum and
common salt.

32. Surface-soil of a field near Paddingbuttel.
This field is particularly adapted for the growth of
red clover. 100 parts consist of: —

Silica and siliceous sand

Alumina ....

Peroxide of iron

Peroxide of manganese

Lime .....

Magnesia ....

Potash, principally in combination with silica

Soda, idem ....

Phosphoric acid . . . .

Sulphuric acid . ...

Chlorine (in common salt)

Humus, soluble in alkaline carbonates

Humus, with nitrogenous matter

93-720
1*740
2-060
0*320
0121
0*700
0062
0-109
0103
0005
0050
0*890
0-120

100-000

SOILS IN BOHEMIA.

33. Surface-soil of a very fertile field in the prov-
ince of Dobrawitz and Lautschin. 100 parts gave

Siliceous sand, with much maffnetic iron sand
Earthy part separated by the sieve

4-286
95714

100-000

238

ON THE CHEMICAL CONSTITUENTS OF SOILS.

An aqueous infusion of the soil contained gypsum,
common salt, magnesia, and humus. 100 parts of
the soil gave : —

Silica . . ,

Alumina

Protoxide and peroxide of iron

Peroxide of manganese

Lime

Magnesia

Potash, in combination with silica

Soda, idem (principally) .

Phosphoric acid, in combination with lime

Sulphuric acid, idem

Chlorine (in common salt)

Humus, soluble in alkalies

Humus

Nitrogenous matter

89-175
2-652
3-136
0-320
1-200
1-040
0-075
0354
0-377
0081
0066
0-920
0-456
0-208

100000

34. Surface-soil of a very fertile field in the prov-
ince of Dobrawitz and Lautschin. 100 parts of the
earth consisted of: —

Siliceous sand, with a little magnetic iron sand . 43-780
Finer part separated by the sieve . . 56-220

100000

100 parts yielded to water 0*175 part of salts,
consisting of common salt, gypsum, magnesia, and
humic acid. 100 parts, by weight, of the earth con-
sisted of: —

loiiica . . • • *

Alumina ....

Protoxide and peroxide of iron

Peroxide of manganese .

Lime . . . . .

Magnesia ....

Potash, in combination with silica

Soda, idem, ....

Phosphoric acid, in combination with lime

Sulphuric acid, idem

Chlorine (in common salt)

Humus, soluble in alkalies

Humus . . . . .

Nitrogenous matter

. 89.634

3224
. 2-944

1-160
. 0-349

0-300
. 0-160

0-428
. 0-246

0-005
. 0-012

0-750
. 0-340

0-448

100-000

35. Analysis of a soil formed by the disintegration
of basalt. 100 parts of the earth consisted of: —

ON THE CHEMICAL CONSTITUENTS OF SOILS.

239

Siliceous sand, with very much magnetic iron sand 8*428
Earthy portion of the soil .... 91-572

100000

The aqueous infusion of the earth contained only
traces of common salt and gypsum, with humus,
lime, and magnesia. 100 parts consisted of: —

Silica .....

. 83-642

Alumina .....

3-978

Protoxide and peroxide of iron

. 5-312

Peroxide of manganese

0-960

Lime .....

. 1-976

Magnesia .....

0-650

Potash, in combination with silica

. 0080

Soda, idem .....

0145

Phosphoric acid, in combination with lime

. 0273

Sulphuric acid, idem . . . .

a trace

Humus, soluble in alkaline carbonates .

. 1-270

Chlorine . . . . . .

a trace

Humus, .....

. 0234

Nitrogenous matter ....

1-480

100 000

Manure consisting of gypsum, common salt, or
ashes of wood, would be highly conducive to the
fertility of this land.

SOILS IN THE " MARKGRAFSCHAFT MAHREN."

36. Surface-soil of a field very remarkable for its
fertility. The field is called Haargraben, and is
situated near the village of Nebstein. It has never
been manured or allowed to lie fallow and yet has
produced for the last 160 years the most beautiful
crops ; thus furnishing a remarkable example of un-
impaired fertility. 100*000 parts of this soil con-
sisted of: —

Coarse and fine siliceous sand, with a little mag-
netic iron sand ....
Earthy matter .....

35-400
64 600

100 000

100 parts of the earth yielded to water 0*010 sul-
phuric acid, 0-010 chlorine, 0-007 soda, 0-012 mag-
nesia, 0-010 potash, with a little silica, humus, and

240 ON THE CHEMICAL CONSTITUENTS OF SOILS.

nitrogenous matter, but no appreciable trace of
trates. 100 parts of the soil contained: —

Silica

Alumina

Peroxide of iron

Peroxide of manganese

Lime

Magnesia

Potash, principally in combination with silica

Soda, idem

Phosphoric acid, combined with lime and iron

Sulphuric acid, combined with lime

Chlorine (in common salt)

Humus, soluble in alkalies

Humus ....

Nitrogenous matter

77-209
8-514
6-592
1-520
0-927
1-160
0-140
0640
6-651
0-011
0-010
0-978
0-540
1108

100-000

ni-

It is apparent from the above analysis that, not-
withstanding the long period during which this land
h^s been cultivated without manure, it still remains
very rich in matters adapted for the nutrition of
plants.

SOILS IN HUNGARY.

37. Analysis of a very fertile soil from Esakang.
100 parts of the earth contained : —

Very fine siliceous sand
Earthy matter

. 2-820
97-180

100 000

The aqueous decoction of the soil contained princi-
pally gypsum, common salt, silica, magnesia, and

humus. 100 parts of the soil yielded : —

Silica ....

Alumina

Peroxide and protoxide of iron

Peroxide of manganese

Carbonate of lime

Carbonate of magnesia

Potash, combined with silica •

Soda, combined with silica

Phosphoric acid, combined with lime

Sulphuric acid

Chlorine in common salt . •

76-038
4-654
6112
0-900
3771
4-066
0-030
1-379
0-546
0021
0015

ON THE CHEMICAL CONSTITUENTS OF SOILS.

241

Humus, soluble in alkalies

Humus

Nitrogenous organic matter

1-160
1100
0-208

100000

Subsoil of the same field at a depth of two feet.
100 parts consist of: — ■

Very fine siliceous sand with scales of mica 2-408

Earth separated by the sieve . . , 97-592

100-000

100 parts of the earth contain : —

Silica .....

. 59-581

Alumina ....

3-224

Peroxide and protoxide of iron

. 4-896

Peroxide of manganese

0-720

Carbonate of lime . ,

. 17-953

Carbonate of magnesia

11-075

Potash, combined with silica

. 0-150

Soda, principally combined with silica

0-891

Phosphoric acid, combined with lime

. 0 846

Sulphuric acid, idem . . . .

0-004
. 0'(m

Chlorine in common salt

Humus, soluble in alkalies

0-536

Humus, with nitrogenous organic matter .

. 0-120

100-ooa

BELGIUM.

38. Surface-soil of a field distinguished for its fer-
tility. It had received no manure for twelve years pre-
vious to the time at which the analysis was executed.
The rotation of crops for the latter nine years was as
follows : — 1. beans, 2. barley, 3. potatoes, 4. winter
barley with red clover, 5. clover, 6. winter barley,
7. wheat, 8. oats ; during the ninth year it was
allowed to lie fallow. The soil is more clayey than
loamy, and of a very fine grain. Water extracted
from the soil, 0-013 soda, 0*002 lime, 0-012 magnesia,
0-009 sulphuric acid, 0-003 potash, 0-003 chlorine,
with traces of silica and humus. 100 parts con-
tained : —

Silica

Alumina

Peroxide and protoxide of iron

Peroxide of manganese

Carbonate of lime

64-517
4810
8316
0 800
9-403

242

ON THE CHEMICAL CONSTITUENTS OF SOILS.

Carbonate of magnesia

Potash, principally combined with silica

Soda . . . .

Phosphoric acid

Sulphuric acid . .

Chlorine . . .

Humus ....

10-361
0100
0013
1-221
0009
0 003
0-447

100-000

ENGLAND.

39. Surface-soil of a very fertile sandy field from
the vicinity of Tunbridge, Kent, according to Davy.
100 parts consisted of: —

Loose stones and gravel

• •

. 13-250

Sand and silica

• •

58-250

Alumina

• •

. 3-250

Beroxide of iron

• •

1-250

Carbonate of lime

• •

. 4-750

Carbonate of magnesia

• •

0-750

Common salt and extractive matter

. 0-750

Gypsum

• •

0-500

Matter destructible by heat

• •

. 3-750

Vegetable fibre

• •

3-500

Water

• •

. 5-000

Loss

• •

5-000

100-000

The great Davy, who was convinced of the impor-
tance of the inorganic constituents of soils, has
omitted to detect the phosphoric acid, potash, soda,
and manganese. All these must have been present
in the soil, for we are informed that it produced
good hops, for which these ingredients are indis-
pensable.

40. A good turnip soil from Holkham, Norfolk,
yielded to Davy : —

Siliceous sand

Silica

Alumina

Peroxide of iron

Carbonate of lime

Vegetable and saline matter

Moisture . ~ .

88-888
1-666
1222
0-334
7-000
0556
0-334

100000

ON THE CHEMICAL CONSTITUENTS OF SOILS. 243

In this case also, phosphoric acid, manganese,
potash, magnesia, &c., have escaped detection by
this acute chemist; yet doubtless they must be
present in the soil, for we are informed that it pro-
duces good turnips.

41. An excellent wheat soil from the neighborhood
of West Drayton, Middlesex, according to Davy.
100 parts contained: —

Sand and silica .... 72*800

Alumina ..... 11-600

Carbonate of lime .... 11-200

Humus and moisture . . . 4*400

100*000

This analysis has been executed so imperfectly,
that it only conveys a very feeble representation of
the nature of the soil. A soil which bears good
wheat must contain phosphate of potash, soda, chlo-
rine, and sulphuric acid ; yet none of these are exhib-
ited by the analysis.

42. Surface-soil of a fertile field in the neighbor-
hood of Bristol. 100 parts contained : —

Silica and siliceous sand . . . 60*000

Alumina ..... 12000

Peroxide of iron . , . . 3*500

Lime (carbonate) . . . . 7*500

Magnesia ..... 0*500

Humus ...... 1*250

Saline and extractive matter . . 0*750

Water ...... 14*500

100000

Davy has made several analyses of various fertile
soils, and since his time numerous other analyses
have been published ; but they are all so superficial,
and in most cases so inaccurate, that we possess no
means of ascertaining the composition or nature of
English arable land.

SWEDEN.

43. Surface-soil of a field which produces the most
abundant crops, and has never been manured. (Ber-
zelius.) 100 parts consist of: —

244

ON THE CHEMICAL CONSTITUENTS OF SOILS.

Siliceous sand ....

Silica .....

Alumina .....

Phosphates of lime and iron

Carbonate of lime ....

Carbonate of magnesia

Insoluble extractive matter

Insoluble extractive matter destructible by heat

Animal matter ....

Resin .....

Loss .....

57900
14-500
2000
6000
IJIOO
1-000
1-250
4-000
1-600
0250
0400

100-000

This great chemist has strangely omitted to detect
in the soil potash, soda, chlorine, sulphuric acid, and
manganese. As this soil is eminent for its fertility,
there cannot be the slightest doubt that all these
ingredients must have existed in it in notable quan-
tity.

ISLAND OF JAVA.

44. A very fine-grained loamy soil, colored yellow
by peroxide of iron, consisted of;

Silica and siliceous sand

Alumina

Peroxide and protoxide of iron

Peroxide of manganese

Lime ....

Magnesia

Potash, principally in combination with silica

Soda, idem

Phosphoric acid

Sulphuric acid

Chlorine

Humus

Water, with carbonic acid

100-000

•

. 67-660

13-572

•

. 10-560

1-640

•

. 0-912

0-570

th silica

. 0030

0-184

. 0-391

0-038

. 0010

0368

•

. 4065

"WEST INDIES (pORTO RICO).

45. Surface-soil of a very barren field. 100 parts
contained : —

ON THE CHEMICAL CONSTITUENTS OF SOILS. 245

Silica and siliceous sand

•

• •

70-900

Alumina

• •

•

6-996

Peroxide, and protoxide of

iron (much

magnetic

iron sand)

• •

•

6102

Peroxide of manganese

0-200

Lime

• •

•

2-218

Magnesia

•

3-280

Potash

• •

•

0-130

Carbonate of soda

6-556

Phosphoric acid, combined with lime

•

1-362

Sulphuric acid, combined with lime

0-149

Chlorine in common salt

, ,

•

0067

Humus, soluble in alkalies

0 540

Humus

• •

•

1-500

100-000

This soil is improved by gypsum. Its sterility is
due to the excessive quantity of carbonate of soda
which is present.

NORTH AMERICA.

46. Surface-soil of alluvial land in Ohio, remark-
able for its great fertility. 100 parts consisted of: —

Silica and fine siliceous sand . . • 79-538

Alumina ..... 7-306
Peroxide and protoxide of iron (much magnetic

iron sand) .... 5-824

Peroxide of manganese . . . 1-320 •

Lime ..... 0-619

Magnesia ..... 1024

Potash, principally combined with silica . 0-200

Soda . • . - . ; - . * - ^^24
Phosphoric acid, combined with lime and oxide of

iron ...... 1-776

Sulphuric acid, combined with lime . . 0-122

Chlorine .... . 0 036

Humus, soluble in alkalies . . . 1-950

Nitrogenous organic matter . . . 0*236

Wax and resinous matter . . . 0-025

100000

47. (A.) Surface-soil of a mountainous district in
the neighborhood of Ohio. (B.) analysis of the
subsoil. This soil is also distinguished for its great
fertility. 100 parts contain : —

21*

246

ON THE CHEMICAL CONSTITUENTS OF SOILS.

(A)

(B)

. 87143

94-261

5-666

1-376

. 2220

2-336

0-360

1-200

. 0-564

0 243

0-312

0-310

a . 0 120 )
0-025 5

0-240

. 0-060

a trace

0-0-27

0034

0036

a trace

1-304

. 1072

0-080

1011

100-000

Silica with fine siliceous sand

Alumina

Peroxide and protoxide of iron

Peroxide of manganese .

Lime ....

Magnesia

Potash, principally combined with silica

Soda ....

Phosphoric acid ...

Sulphuric acid .

Chlorine • . . .

Humus, soluble in alkalies

Humus ....

Carbonic acid, combined with lime

Nitrogenous organic matter

In the preceding part of the chapter we have in-
serted a number of analyses of various soils, as well
as the conclusions deduced from them, by means of
which the farmer may be enabled to ascertain the
manures best adapted for each variety of soil. By
inspecting the analyses of the sterile soils, it will be
apparent that it is in the power of chemistry to point
out the causes of their sterility. The general cause
which conduces to the sterility of soils is either the
absence of certain constituents indispensable for the
growth of plants, or the presence of others, which

* Soil from Chelmsford, Massachusetts, on the Merrimack river,

which has produced a large crop of wheat for 20 years, with only one

failure, analyzed by Dr. Dana. 100 parts contain : —

Soluble geine 3.9228

Insoluble " . . . . . 2-6142

Sulphate of lime ..... -7060
Phosphate of '* . . . . -9082

Silicates (silica, alumina, iron &c.) . . 91-8485

No trace of carbonate of lime, or of alkaline salts, could be discovered.
Soil from Maine, analyzed by Dr. Jackson, has produced 48 bushels

of wheat per acre.

Water . . . . . .5-0

Vegetable matter .... 17-5

Silica ...... 54-2

Alumina ..... 106

Subphosphate of alumina . . . .3-0

Peroxide of iron .... 7-0

Oxide of manganese . .... 1*0

Carbonate of lime . . . . TS

99-8
From Hitchcock's Final Report^ p. 29.

ON THE CHEMICAL CONSTITUENTS OF SOILS. 247

exert an injurious or poisonous action. The analy-
ses are those of Dr. Sprengel, — a chemist who has
unceasingly occupied himself for the last twenty
years in endeavoring to point out the importance
of the inorganic ingredients of a soil for the develop-
ment of plants cultivated upon it. He considers as
essential all the inorganic bodies found in the ashes
of plants. Now, although we cannot coincide with
him in the opinion, that iron and manganese are in-
dispensable for vegetable life, (for these bodies are
found as excrementitious matter only in the bark,
and never form a constituent of an organ,) yet we
gratefully acknowledge the valuable services which
he has rendered to agriculture, by furnishing a natu-
ral explanation of the action of ashes, marl, &c., in
the improvement of a soil. Sprengel has shown,
that these mineral manures afford to a soil alka-
lies, phosphates, and sulphates; and further, that
they can exert a notable influence only on those
soils in which they are absent or deficient. In a
former chapter of this book I have endeavored to
point out the importance of considering these con-
stituents as intimately connected with the vital pro-
cesses of the vegetable organism, and have shown
that the different families of plants contain unequal
quantities of inorganic ingredients. This subject
has been left unexamined by Sprengel, yet it is one
of much importance ; for the application of manures
must be regulated by the composition of the plants
which are cultivated on any particular soil. Still,
the composition of the soil must always be kept in
view. Thus it would be perfect extravagance to
manure certain soils with marl, ashes, or gypsum;
whilst, on the contrary, these compounds would pro-
duce the most beneficial results on other lands.

In a former part of the work, the principal action
of gypsum upon vegetation was ascribed to the de-
composition and fixation of the carbonate of ammonia
contained in rain-water ; but gypsum exerts a two-
fold action. The power of decomposing carbonate

248 ON THE CHEMICAL CONSTITUENTS OF SOILS.

of ammonia, and of fixing the ammonia, is not pecu-
liar to gypsum, but is shared also by other salts of
lime (chloride of calcium, for example). But it acts
also as a sulphate, and when useful as such cannot
be replaced by any other salt of lime which does not
contain sulphuric acid.

Hence gypsum can be replaced as a manure only
by a mixture of a salt of lime with ammonia, and a
salt of sulphuric acid. Sulphate of ammonia can
therefore be substituted for gypsum, and exerts a
more * rapid and effectual action. In France, sul-
phuric acid has been poured upon the fields after the
removal of the crops, and has been found to form a
good manure. But this is merely a process for form-
ing gypsum in situ; for the soils upon which it is
applied contain much lime, which enters into com-
bination with the sulphuric acid. It would certainly
be much more advantageous to form sulphate of am-
monia by adding the acid to putrefied urine, and to
apply this mixture to the field.

APPENDIX TO PART I.

EXPERIMENTS AND OBSERVATIONS ON THE ACTION OF CHARCOAL
FROM WOOD ON VEGETATION.

BY EDWARD LUCAS.*

** In a division of a low hothouse in the botanical garden
at Munich, a bed was set apart for young tropical plants,
but instead 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, such as tan communicates, when in a state of fer-
mentation. The plants placed in this bed of charcoal quick-
ly vegetated, and acquired a healthy appearance. Now, as
always is the case in such beds, the roots of many of the
plants penetrated through the holes in the bottom 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 Thun-
bergia alata, and the genus Peireskicc, throve quite aston-
ishingly ; the blossoms of the former were so rich, that all
who saw it affirmed, they 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 ap-
ply the pollen by the hand. The Peireskice grew so vigor-
ously, 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 spontaneously, and the
abundant appearance of young Filices, naturally attracted
my attention, and I was gradually led to a series of ex-
periments, the results of which may not be uninteresting ;

* See page 78.

250 APPENDIX TO PART I.

for, besides being of practical use in the cultivation of most
plants, they demonstrate also several facts of importance
to physiology. The first experiment which naturally sug-
gested itself, was to mix a certain proportion of charcoal
with the earth in which different plants grew, and to in-
crease its quantity according as the advantage of the meth-
od was perceived. An addition of | charcoal, for exam-
ple, to vegetable mould, appeared to answer excellently for
the Gesneria and Gloxima, and also for the tropical Aroidece
with tuberous roots. The first two soon excited the atten-
tion of connoisseurs, by the great beauty of all their parts
and their general appearance. They surpassed very quick-
ly those cultivated in the common way, both in the thick-
ness of their stems and dark color of their leaves ; their
blossoms were beautiful, and their vegetation lasted much
longer than usual, so much so, that in the middle of Novem-
ber, 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 ornamental plants on account of the beautiful coloring
of their leaves, (I mean, such as the Caladium bicolor,
Pidumy Pcecile, &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 Bromeliacece
and LiliacecB, with the Citrus and Begonia also, and even
with the Palmce. 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 results were obtained. Cuts of plants from different
genera took root in it well and quickly ; I mention here
only the Euphorbia fastuosa ^ndfulgens which took root in
ten days, Pandanus utilis in three months, P. amaryllifolius,
Chammdorea elatior in four weeks. Piper nigrum, Begonia^
Ficus, Cecropia, Chiococca, Buddleya, Hakea, Phyllanthus,
Capparis, Laurus, Stifftia, Jacquinia Mimosa, Cactus, in

ACTION OF CHARCOAL ON VEGETATION. 251

from eight to ten days, and several others, amounting to
forty species, including Ilex and many others. Leaves,
and pieces of leaves, and even pedunculi^ or petioles, took
root and in part budded in pure charcoal. Amongst others
we may mention the foliola of several of the Cycadecz, as
having taken root, as also did parts of the leaves of the
Begonia Telfairice, and Jacaranda brasiliensis ; leaves of the
Euphorbia fastuosa, Oxalis Barrilieri, Ficus, Cyclamen,
Polyanthes, Mesembryanthemum ; also the delicate leaves
of the Lophospermum and Mariynia, pieces of a leaf of the
Agave americana ; tufts of Pinus, &c. ; and all without the
aid of a previously formed bud.*

**Pure charcoal acts excellently as a means of curing
unhealthy plants. A Dorianthes excelsaj for example, which
had been drooping for three years, was rendered com-
pletely healthy in a very short time by this means. An
orange tree which had the very common disease in which
the leaves become yellow, acquired within four weeks its
healthy green color, when the upper 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 with 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 substance on vegetation ; but the reader
who takes particular interest in the subject will find more
extensive observations in the 'Allgemeine Deutsche Garten-
zeilung ' of Otto and Dietrich, in Berlin ; or Loudon's
Gardener^ s Magazine, for March, 1841.

*'The charcoal employed in these experiments was the
dust-like powder of charcoal from firs and pines, such as is
used in the forges of blacksmiths, and may be easily pro-
cured in any quantity. It was found to have most effect
when allowed to lie 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

* The cuttings of several of these plants being full of moisture, require
to be partially dried before they are placed in the soil, and are with
difficulty made to strike root in the usual method. The charcoal is
probably useful from its absorbing and antiseptic power. The Hakea
is extremely difficult to propagate from cuttings. All the Laurus tribe
are obstinate, some of them have not rooted under three years from the
time of planting. — fF.

252 APPENDIX TO PART I.

animal charcoal, although I foresaw the probability 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 suppUed
with water, since the air having such free access penetrates
and dries the roots, so that unless this precaution is taken
the failure of all such experiments is unavoidable.

'*The action of charcoal consists primarily in its pre-
serving the 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 propaga-
tion. There can scarcely be a doubt also that the char-
coal undergoes decomposition ; for after being used five to
six years it becomes 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 substance
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 favorable influence by decomposing and absorb-
ing the matters excreted by the roots, so as to keep the
soil free from the putrefying substances which are often
the cause of the death of the spongiolce. 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

* M Lucas has recently repeated these experiments, and found that
the animal charcoal obtained by the calcination of bones possesses a
decided advantage over all other kinds of charcoal, which he subjected
to expeiiment — Liebig's Annalen^ Band xxxix. Heft I. 5. 127.

t As some misconception has arisen regarding this explanation of the
action of charcoal upon vegetation, and an idea propagated, that the
introduction of these opinions into this work incorporated them with
those of Liebig, it is necessary to state that they are merely inserted
here as part of the papers of M. Lucas. The true explanation has
been given in a former part of the work, viz. that charcoal possesses
the power of absorbing carbonic acid and ammonia from the atmo-
sphere, which serve for the nourishment of plants — Ed.

ON A MODE OF MANURING VINES. 253

belonging to a great many different families were sub-
jected to trial." [Buchner's Repertorium, ii. Reihe, xix.
Bd. S. 38.)

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 pre-
ceding 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
without 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 statements, both of which merit complete con-
fidence, 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 considerable amount
must be extracted from the soil.

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 dis-
integration 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 produce 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 pro-
portion 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 Wachenheimer 172 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^
22

254 APPENDIX TO PART I.

metre of land, and 1000 parts of the pruned branches con-
tain 56 to 60 parts of carbonate, or 38 to 40 parts of pure
potash. Hence it is evident that 4.5 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 quan-
tity of branches are yearly taken from the above extent
of surface.

In the vicinity of Johannisberg, Rudesheim, and Budes-
heim, 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.

'* 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 prac-
tised 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 excellent 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

* Slightly abridged from an article by M. Krebs of Seeheim, in the
" Zeitschrift fur die landwirthschaftlichen Vereine des Grosherzogthums
Hessenr No. 28, July 9, 1840.

ON THE MANURING OF THE SOH. IN VINEYARDS. 255

putrefaction so completely, that, as I have learned by ex-
perience, 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 * Geschichte der
Weine der alien und neuen Zeit ' : —

*' *The best manure for vines is the branches pruned
from the vines themselves, cut into small pieces, and im-
mediately 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, wondering 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 de-
cay, 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 branch-
es 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 bet-
ter, and become strong and green. I dug therefore my
vineyard as deep as if I would put dung into it, and cut the
branches into pieces, placing them in the holes and cover-
ing them with earth. In a year I had the very great satis-
faction to see my barren vineyard become quite beautiful.
This plan I continued every year, and now my vines grow

* Badisthes landwirthschaftliches IVochenblatt, v. 1834, S. 52 and 79.

256 APPENDIX TO PART I.

Splendidly, and remain the whole summer green, even in
the greatest heat.

" 'AH my neighbors wonder very much how my vine-
yard is so rich, and that I obtain so many grapes from it,
and yet they all know that 1 have put no dung upon it for
ten years.' ""^

ROOT SECRETIONS.

It should be stated, that the accuracy of the experiments
of Macaire-Princep adduced by the author, page 164, is
not generally admitted. Other chemists have been unable
to obtain similar results, or if they do are inclined to as-
cribe them to injury of the roots of the plants examined.
Professor Lindley in his notice of Liebig's work has re-
marked, 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 mat-
ter, from various parts of their surface, and in the peculiar
substances lodged in the hollows of their stems or elsewhere,
such as Tabasheer, in the bamboo. These are thought to
be instances, ''sufficient to satisfy the necessity of excre-
tions occurring, and to render it superfluous to look to the
roots for further aid in this particular."

The subject of excretion is one of great interest, and
deserving of further examination. Several botanists have
recently stated what are deemed fatal objections to the cor-
rectness of De Candolle's conclusions from Macaire's ex-
periments. It is maintained, that the process of excretion
from the roots of plants is not analogous to that of excretion
in animals ; that the deposits consist of materials which
were in superabundance in the system of the plant, and
that the reason why the same species of plants do not grow
one after the other, is, that the first exhausted the soil of
the materials necessary for the nourishment of the next.
In some parts of the world, wheat crops are said to have
been obtained fifty years in succession, where the supply
of nutriment was sufficient. The application of the recent
discovery of the means of coloring the wood of trees by

* The experiment has been made here with success — fV.

ROOT SECRETIONS. 257

introducing coloring matters into their trunks, is reported
to have shown that the coloring matters are thrown off
from the roots, and plants growing near them have been
poisoned, although the plant colored continued to grow.
Report of British Association Meeting, August, 1841.

A series of experiments on this subject has been going
on during five years in the Botanic Garden, Oxford, under
the direction of Professor Daubeny. His object is to as-
certain, '* in the first place, how many successive years the
soil may admit of the growth of the same crop, and, if it
becomes deteriorated, at what rate the decrease of produce
may proceed ; and, in the second place, what kind of vege-
tables will afterwards thrive best in soil, which, with refer-
ence to this particular crop, has become damaged, or
effete.

" With a view to determine this, I have set apart, in one
portion of our Botanical Garden, a number of distinct plots
of ground, of known size, and uniform as to quality.

*' These were in the first instance enriched with an equal
amount of manure, and brought, as nearly as could be
done, in every respect into a similar condition.

'* Fifteen of these beds are planted year after year, with-
out intermission, with the following crops : viz. potatoes,
turnips, barley, oats, poppies [Papaver somniferum), buck-
wheat, tobacco {JVicotiana rustica), flax, hemp, endive,
clover (Trifolium pratense), mint {Mentha viridis), beans,
parsley, and beet.

• "The remaining fifteen beds receive in turn the same
crops, but each year a different one is introduced ; so that
by comparing the amount of produce obtained each year
from the first and second class of beds, — those in which
the crop is permanent, and those in which it is made to
shift about, — we may be enabled to learn, how much of
any actual diminution ought to be attributed to the season,
and how much to a deterioration or exhaustion of the soil.

** As it is scarcely five years since the experiments were
commenced, the progress made has not yet been sufficient
to render the results worth quoting ; but should life and
leisure be allowed me for bringing them to a conclusion,
I trust some inferences may hereafl«r be deduced of utility
to future husbandmen ; although I should be far more
sanguine with respect to the benefit that would accrue, if a
piece of ground of greater extent were set apart for such
experiments, as, under the auspices of any of our great
Agricultural Societies, it might not be difliicult to efl^ect.

22*

258 APPENDIX TO PART I.

** Should Science, indeed, succeed in settling the true
cause of the deterioration of crops, and the most advan-
tageous order of their succession, it is unnecessary for me
to point out how important a boon she would confer upon
the agriculturist.

*'So extremely various, indeed, are the systems upon
which the rotation is carried on in different countries, that ;
no fixed principle would appear to regulate them, and the '
whole may be considered, as being founded much more
upon the authority of long usage and tradition, than upon
any actual comparison of the relative advantages of those
resorted to in various places.

"This inquiry may therefore be pointed out, as being
one of those lines of investigation, in prosecuting which
the scientific chemist may be expected to benefit the prac-
tical farmer."

PEAT COMPOST.
(Seep. 118, and 185.)

According to the statement of Messrs. Phinney and
Haggerston, as contained in the Report on the Geological and
Agricultural Survey of Rhode Island, by Dr. C. T. Jack-
son, a compost made of three parts of peat and one of sta-
ble manure, is equal in value to its bulk of clean stable
dung, and is more permanent in its eflTects.

Dr. Jackson deems it essential that animal matters of
some kind should be mixed with the peat, to aid the de-
composition and produce the requisite gases. Lime de-
composes the peat, neutralizes the acids, and disengages
the ammonia. The peat absorbs the ammonia, and be-
comes in part soluble in water. The soluble matter, ac-
cording to Dr. Jackson, is the apocrenate of ammonia ;
crenate of ammonia and crenate of lime being also dis-
solved. With an excess of animal matter and lime, free
carbonate 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 deserve the attention of every
agriculturist. He gives the following details of the man-

PEAT COMPOST. 259

ner in which the compost was prepared upon the farm of
Mr. Sandford, near the village of VVickford in North King-
ston. " In the corner of the 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 offish was added,
and the fish were spread on the surface of the muck, and
allowed to become putrescent. The moment they began to
decompose, he again covered them with peat, and a renew-
ed layer of fish was spread and covered in the same man-
ner. 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 de-
composition in two or three weeks. Such a heap should
be rounded up and covered, so as to prevent the rain wash-
ing 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 absorb-
ing 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 carcass of a dead horse, which
is often suffered 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 Letters of Jlgricola, Letter 25, p. 238.*

Night soil may be composted with peat with great advan-
tage, sufficient lime being added to deprive it of odor; large
quantities of ammonia are given off* and absorbed. t

Appended to Dr. Jackson's Report will be found a letter

* In a Report on a Reexamination of the Geology of Massachusetts,
1838, Dr. Dana particularly notices the evolution of ammonia from fer-
menting dung, and supposes that the ammonia combines with geine to
form a soluble compound. See JVote to page 83 of the Report.

f Mght-SoiL The quantity of night-soil collected and removed from
the city of Boston annually, is about four hundred thousand square feet.
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 199.

260 APPENDIX TO PART I. <

from E. Phinney, Esq., of Lexington, well known as one
of the most skilful agriculturists, "On the reclaiming of peat
bogs and the employment of peat as manure."

SOURCE OF THE CARBON OF PLANTS. (fROM DAUBENY's
LECTURES ON AGRICULTURE, 1841.)

(See Chapter II.)

** Until within the last century, it would have been taken
for granted, that the soil was the source from whence pro-
ceeded all the solid matter at least which entered into the
constitution of a plant, and there were several circumstan-
ces which tended to countenance such an opinion. No
plants, it was observed, would continue long to thrive in
earth unmixed with some proportion of vegetable mould,
and the fertility of the latter is greatly enhanced by the
addition of animal or vegetable matter, in that state of de-
cay, in which it becomes soluble in water, and therefore
fitted to obtain admission into the vessels of plants.

"Hence, when Priestley had demonstrated, that leaves
decompose the carbonic acid of the atmosphere, giving out
its oxygen and assimilating its carbon, the doctrine alluded
to still to a certain extent maintained its ground; and it was
even questioned by Ellis and others, whether in fact, if we
were to strike the balance between the opposite influence
of a plant during the day and the night, as much carbonic
acid might not be exhaled by it at one period, as had been
decomposed at another.

*' I was therefore induced myself to undertake some ex-
periments,* the results of which appear to establish, that
plants, even in a confined atmosphere, do in reality add a
great deal more oxygen to the air than they abstract from
it, whilst the amount of carbonic acid which may be intro-
duced undergoes at the same time a corresponding dimi-
nution.

'' This effect I even found to take place in diffused light,
as well as under the direct influence of the solar rays, and
to be no less common in aquatic than in terrestrial plants.

*' I also showed, that when a branch loaded with flowers,
as well as with leaves, was introduced into a jar containing

<* * See Philosophical Transactions for 1836."

DAUBENY ON THE CARBON OF PLANTS. 261

a certain proportion of carbonic acid, the balance still con-
tinued to be in favor of the purifying influence of the veg-
etable.

'*The apparatus I made use of consisted of a large bell-
glass jar, containing in one case 600, in another 800 cubic
inches of air,* and suspended by pulleys. Its edges dipped
into quicksilver, contained in a double iron cylinder of cor-
responding dimensions to the jar, which, being closed at
bottom, constituted a well of about six inches in depth, cal-
culated to receive a fluid, and to admit of the glass vessel
moving freely in it. The inner margin of this hollow cylin-
der was cemented air-tight, according as circumstances re-
quired, either to a plate of iron, or to a pot of the same
material upon or in which the plant operated on might be
placed ; and the jar was then let down upon it, until its
edges were sunk a little beneath the surface of the mercury.

"Thus all communication with the external atmosphere
'was cut oflf, and the eflfect of the plant upon the air inclosed
in the jar was readily measured, by simply pressing down
the latter, and thus expelling a portion of its contents
through a tube, communicating with its interior, and intro-
duced at its outer extremity under a pneumatic trough,
wherein the air might be collected and examined. By con-
necting this extremity with a vessel containing a measured
quantity of carbonic acid, and raising the jar a little in the
well of mercury, it was easy to draw in any proportion of
that gas, with which it was thought proper that the plant
should be supplied. A portion of the air was always tested,
immediately after the introduction of every fresh portion
of carbonic acid, and again after an interval of some hours,
and the proportion of this gas and of oxygen present was
each time carefully registered. The amount of carbonic
acid was determined by a solution of potass, that of oxygen
by the rapid combustion of phosphorus with a portion of it
introduced into a bent tube.

'' Such was the mode of procedure, when an entire plant
became the subject of experiment ; but some of the most
satisfactory trials were with branches of certain shrubs,
themselves too large to be admitted under the jar. These
branches, without being detached from the parent trunk,
were introduced through a hole in the centre of two corre-
sponding semicircular plates of iron, which were cemented
air-tight, to the inner margin of the iron cylinder on the

** * Larger jars, containing from 1200 to 1300 cubic inches were lat-
terly employed."

262 APPENDIX TO PART I.

one hand, and to the stem of the branch on the other. In
this manner, when the jar came to be placed over them,
and to dip beneath the surface of the mercury, the external
air was as effectually excluded, as when the whole of the
plant had been enclosed.

^*The results of several experiments conducted after
this plan are given in a tabular form in the Memoir ; but
it may be sufficient here to specify one of the most satis-
factory of those undertaken. In this case the jar itself
contained about 600 cubic inches of air, and the plant ex-
perimented on was the common lilac {syringa vulgaris).
The proportion of carbonic acid in the jar was each morn-
ing made equivalent to five or six per cent, by additions
through the tube.

*'The first day no great alteration in the air was detect-
ed, but on the second day, by eight in the evening, the
oxygen had risen to ^6'5 per cent. In the morning it had
sunk to 26 0, but by two P. M. it had again risen to no less
than 29*75, and by sunset it had reached 30*0 per cent. At
night it sunk one half per cent. ; but the efl^ect during the
following day was not estimated, as the sickly appearance
which the plant now began to assume induced me to sus-
pend the experiment.

''In a second trial, however, the branch of a healthy
lilac growing in the garden was introduced into the same
jar, where it was suffered to remain until its leaves became
entirely withered.

"The first day the increase of oxygen in the jar was no
more than 025 per cent., but on the second it rose to 25*0.
At night it sunk to nearly 22*0 per cent., but the next
evening it had again risen to 27 0. This was the maximum
of its increase, for at night it sunk to 26*0. and in the
morning exhibited signs of incipient decay. Accordingly
in the evening the oxygen amounted only to 26*5 ; the
next evening to 255 ; the following one to 24*75 ; and the
one next succeeding it had fallen to the point at which it
stood at the commencement, or to 21*0 per cent.

*'The reason of this decrease was, however, very mani-
fest from the decay and falling off* of the leaves ; so that
this circumstance does not invalidate the conclusion which
the preceding experiments concur in establishing, namely,
that in fine weather a plant, so long at least as it continues
healthy, adds considerably to the oxygen of the air when
carbonic acid is freely supplied.

*' In the last instance quoted, the exposed surface of all

DAUBENY ON THE HYDROGEN OF PLANTS. 263

the leaves enclosed in the jar, which were about fifty in
number, was calculated at not more than 300 square inches,
and yet there must have been added to the air of the jar as
much as 26 0 cubic inches of oxygen, in consequence of
the action of this surface upon the carbonic acid introduced.

** But there is reason to believe, that even under the cir-
cumstances above stated (which appear more favorable to
the due performance of the functions of life than those to
which Mr. Ellis's plants were subjected), the amount of
oxygen evolved was much smaller than it would have been
in the open air, for I have succeeded, by introducing sev-
eral plants into the same jar of air in pretty quick succes-
sion, in raising the amount of oxygen contained from twen-
ty-one to thirty-nine per cent., and probably had not even
then attained the limit to which the increase of this con-
stituent might have been brought.

'^ How great then must be the effect of an entire tree in
the open air under favorable circumstances ! and we must
recollect that, cceteris paribus^ the circumstances will be
favorable to the exertion of the vital energies of the plant,
within certain limits at least, in proportion as animal respi-
ration and animal putrefaction furnish to it a supply of car-
bonic acid.

*' These experiments were published in the Philosophical
Transactions for 1836, and have been noticed in Dr. Lind-
ley's popular Introduction to Botany ; neither am I aware
that the deductions which were drawn from them have any-
where been disputed."

Source of the Hydrogen of Plants; from Daubeny^s Lectures,

(See Chapter IV.)

**It would seem, I think, from the late important re-
searches of M. Payen, that the decomposition of water
commences subsequently to that of carbonic acid, whether
it be, that the former process requires a greater develop-
ment and energy in the vegetable functions, or that it takes
place in organs of a different description and of later
growth.

''M. Payen seems to have established, that under the
general term of ligneous fibre, or lignin, we have hitherto
confounded at least two distinct substances, namely, that
which constitutes the walls of the cells, and that which, by
being deposited afterwards on the surfaces of the latter,

264

APPENDIX TO PART I.

imparts to them the solidity of texture which woody fibre
possesses.

'*He has succeeded in isolating the two by chemical
means, and has found, that whilst the cellular matter has
exactly the same composition as starch, being composed
of 44*9 carbon, 6*1 hydrogen, 49 oxygen, or 44*9 carbon
and 55*1 of water; the incrusting matter afterwards formed
consists of 53 -76 carbon, 40.2 oxygen, and 6 of hydrogen,
or of 53*76 carbon, 45*2 of water, and 1 of hydrogen.^

^*The composition of the ligneous matter of different
kinds of wood will therefore vary according to the relative
proportion of these two ingredients, as is shown in the
following table of M. Payen : —

Ligneous Bodies.

Carbon.

Hydrogen.

Oxygen.

Incrusting

Incrusting matter of the wood

matter.

53-76

6-00

40-20

100

Wood of Saint Lucia

5290

6-07

4103

Ebony ....

52-85

600

41-15

Walnut ....

5192

5-96

4212

Oak

50-00

620

43-80

Ditto according to Gay-Lus-

sac, and Th^nard

51-45

5-82

42-73

Beech ....

4925

6-10

44-65

Cellular matter .

44-90

6-10

49 00

**This then proves, that, in the formation of the matter
which incrusts and fortifies the walls of the cellular tissue
in wood, though not in that of the cellular tissue itself, a
decomposition of water must have taken place ; since the
1 per cent, of hydrogen which Payen has found in excess,
can only have arisen in this manner.

*'This increase of hydrogen becomes still greater, when,
in the progress of vegetation, the plant begins to secrete
oils, camphors, and other analogous bodies, products,
which, it is to be remarked, abound most within the tropics,
where the light of the sun is most intense.

'* Hence the decomposition of water, no less than that
of carbonic acid, seems due to solar influence, and accord-
ingly, the greater sweetness of subacid fruits, in a warm
than in a cold summer, arises from the transformation of
a larger amount of tartaric or other vegetable acids into
sugar, owing to that separation of oxygen from the former
which is accomplished by the agency of light.

*'The process of assimilation of plants in its most simple

" * Payen has since stated, that this incrusting matter probably con-
sists of two or three different principles."

DAUBENY ON THE NITROGEN OF PLANTS. 265

form may therefore be stated, as consisting in the extrica-
tion of hydrogen from water, and of carbon from carbonic
acid, in consequence of which one of three things must
happen, — either all the oxygen of the water and of the
carbonic acid are separated, as in those bodies which, like
caoutchouc, volatile oils, &c., consist of nothing else but
carbon and hydrogen ; or, secondly, only a part of it is
exhaled, as in the case of the incrusting matter of wood,
and in sugar ; or, thirdly, that belonging to the carbonic
acid alone is decomposed, whilst the water remains, as in
starch and cellular tissue."

Dependence of the nutritive Qualities of Plants on their jyitro^
gen; from Dauheny^s Lectures.

(See page 139.)

'*The dependence of the nutritive qualities of various
articles of food upon the proportion of nitrogen is well
shown in a recent memoir of Monsieur Boussingault,* who
gives, on the authority of the celebrated agriculturist Von
Thaer, a scale of the relative degree of nutriment afforded
by various plants to cattle, and then places by the side of it
a statement of the proportion of azote present in them, from
which it appears, that the nutritious quality of each bears
a pretty constant ratio to the quantity of nitrogen they
contain.

"This may be seen by the following table :

Equiv.

Ordinary hay

100 its azote being 001 18

Red Clover

. 90 . . . 00176

Beans

. . 83 . . . 0-0141

Wheat- straw

. 400 . . . 00020

Potatoes

200 . . . 0-0037

Beet

. 397 . . . 0-0026

Maize

59 . . . 0-0164

Barley

. 54 . . . 0-0176

Wheat .

27 . . . 0-0213

'*When we reflect, indeed, that animal matter, which so
abounds in nitrogen, is nevertheless derived, either directly
or indirectly, from vegetable, it follows, as a necessary
consequence, that existence can only be maintained by the
aid of those principles in plants, which contain a certain
proportion of the element alluded to.

" * Annales de Chimie, Vol. LXIII."

266 APPENDIX TO PART I.

**And this has been shown by the experiments of Ma-
gendie upon dogs, which were fed on sugar, starch, gum,
and other substances destitute of nitrogen, and in a very
short time pined away and died."

Difference between different Plants in their power of decom-
posing Ammonia; from Daubeny^s Lectures,

(See Chapter V.)

**It maybe inferred, from some experiments made by
Boussingault, that a great difference exists between plants
in their power of assimilating nitrogen, and to this differ-
ence that chemist is disposed to attribute the advantage of
alternately growing what are called fallow crops, for the
purpose of refreshing the soil.

*' 'During germination,' he remarks, *the quantity of
azote which seeds contain appears to be on the increase,
but there is this curious difference between different kinds,
that whilst those of leguminous plants, sown in pure earth
and moistened with nothing but distilled water, obtained an
increase of nitrogen which the atmosphere alone could
have afforded, those of barlev and other cerealia remained
in that respect stationary, unless manure were afforded.'

"Boussingault also shows in a subsequent memoir, that
peas, clover, and other legumes absorb azote, even when
planted in a soil that contains no decomposing animal or
vegetable matter, but that the cerealia, although if so
placed, they may grow, do not appear to secrete this
principle.

*' Boussingault, however, does not go so far as to main-
tain, that the latter in no stage of their existence are capa-
ble of discharging this function, but only that the plant
must have already arrived at a higher state of vigor, in
order to derive its supply from such a source.

"It is on the same principle, that although the animal
in general obtains its food from the various organic bodies
on which he subsists, yet that in an early stage of existence,
before his organs are fitted for undergoing the labor of
assimilating such materials, nature has provided him in his
mother's milk with aliment already almost elaborated.

"It is thus, too, that in the seed the embryo is sur-
rounded with a mass of albumen, from which it derives its
support, until its roots become sufficiently vigorous to
extract nourishment from the ground.

"Hence it becomes in most cases necessary, that crops

DAUBENY ON AMMONIA OF PLANTS. 267

cultivated as articles of food should have access to ven-e-
table or animal manure from which they may derive their
azote, but as this supply would soon be exhausted, were it
not at the same time regenerated from the atmosphere, we
see the advantage of intercalating a green fallow crop
ploughed into the ground with others ; as leguminous
plants, according to the experiments of Boussingault, have
the greatest power of absorbing nitrogen from the air.

**On the same principle this chemist suggests the intro-
duction of the Jerusalem artichoke into light soils, which,
owing to the entire absence of mould, appear irreclaimably
barren; this vegetable, the tubers of which afford nourish-
ment to cattle almost equal to potatoes, having great power
of absorbing both carbon and nitrogen from the air, and
thus by degrees generating a certain amount of soil.^

*'Ihave seen this vegetable very commonly cultivated
for the use of cattle, in the light lands of the Grand Duchy
of Baden, and in certain parts of Alsace.

*' But if it be true, as Liebig has endeavored to establish,
that plants obtain every thing except their alkalies and
earthy constituents from the atmosphere, what, it may be
asked, becomes of the theory that attributes the unfitness
of a soil for yielding several successive crops of the same
plant to the excre'tions given out by its roots ?

**For if plants receive the whole of their volatilizable
ingredients from the atmosphere, these excrementitious
matters, being composed chiefly of carbon, hydrogen, and
oxygen, will not be absorbed, and therefore cannot affect
the succeeding vegetation.

**The above inference would seem unavoidable, if it
were considered absolutely proved, that nothing but the
fixed ingredients of a plant were derived from the earth,
but this is not fully established, even with respect to the
humus, much less with respect to the more soluble matters
which the soil contains.

*' These latter, there seems no reason for doubting, may
be taken up by the spongioles of the roots dissolved in

" * It is to be observed, that Boussingault attributes to plants the
power of absorbing nitrogen from the air, but he alleges no proof that
they have that power, and his results may be just as well explained
by supposing them to have different powers of absorbing ammonia.
It is to be remarked, that the helianthus tuberosus belongs to a tribe
of plants remarkable for their power of absorbing and exhaling water,
and hence it is evident, that they will be brought into contact within a
given time with a larger amount of ammonia, than other plants, which
possess a less degree of energy in that respect."

268 APPENDIX TO PART I.

water, together with the alkaline and earthy ingredients
which are derived from the soil, nor am I aware of any
proof that they may not likewise be assimilated when so
introduced.

"The theory of M. Decandolle, therefore, is not affected
by the above experiments, but must rest on its own merits,
and continue to afford a subject for inquiry to the scientific
agriculturist."

Practical Inferences. From Dr. Dauheny^s Lectures on
JigriculturCj delivered at Oxford, 1841.

'^The first inference that may be drawn, relates to the
utility of diligent and frequent tillage, in order to favor the
disintegration of the soil, and the free admission to it of
oxygen and of water.

"Unless the former take place, no fresh alkali can be
extracted from the subjacent rock by the action of water
upon it ; unless the latter be brought about in a sufficient
degree, the humus excluded from air cannot undergo that
process of eremacausis, or gradual combustion, on which
its influence upon the nutrition of plants has already been
shown to depend.

"Hence, in ancient times, the importance attached to
those operations which had this object for their aim, —

" ' Quid est agrum bene colere ? ' asked Cato. * Bene arare. Quid
secundum? Arare. Quid tertium ? Stercorare.*

Thus ploughing was regarded the most important process
in agriculture, after which, though at a long interval, came
manuring.

" The design, therefore, of the agriculturist is, to reduce
the soil to that loose and crumbling condition, in which it
becomes entirely pervious to air and moisture, imparting to
it the quality which the ancients denominated putre.

** * Et cui putre solum, (naraque hoc imitamur arando,)
Optima frumentis.'

"Hence the superiority of spade husbandry over the
plough, if the expense of the labor be not taken into the
account ; hence the fertility of the small farms of the ancient
Romans, notwithstanding their rude methods and their
deficiency of skill ; hence the fine condition of those tracts
of land, which are subjected to the unremitting manual ex-
ertions of societies of men like the Trappists, whose mis-

PRACTICAL INFERENCES. 269

taken views of reliojion have led them into that entire iso-
lation from human society, under which even the severest
physical toil becomes itself a relief.

*' The same principle explains in some degree the utility
of subsoil-ploughing, which, by bringing up to the surface
a portion of earth previously out of the reach of those in-
fluences which tend to cause its disintegration, extracts
from it the alkaline and other ingredients required by the
plant for its subsistence.

** It is found advantageous, in the first instance, merely
to break and pulverize the subsoil to a depth of eighteen
or twenty inches, without bringing it to the surface, and
only after a lapse of four or five years to mix it with the
vegetable mould above, a practice, the utility of which de-
pends, not only on the mechanical condition of the land
being rendered more favorable to culture in consequence
of its becoming more friable, but likewise, probably, owing
to the chemical decomposition of its component parts having
taken place more completely.

'* Other circumstances, such as its influence on the drain-
age of the land, will no doubt cooperate in producing the
benefit which often results from the practice of subsoiling ;
but that the cause pointed out really contributes to its
efficacy, may be inferred from a fact attested by many ex-
perienced agriculturists,^ namely, that those soils are most
benefited by subsoil-ploughing, which can be rendered
thereby more pervious to moisture, and consequently to
air ; whilst those which contain too large a percentage of
clay to be affected in this manner by the process, derive
no advantage from it.

**But it must not be forgotten, that the utmost pains be-
stowed upon its elaboration cannot generate any new prin-
ciples, but only act, by enabling the soil to impart more
readily to the crop those which it already possesses.

*' This obvious truth will explain the cause of the disap-
pointment felt by farmers, at finding, that afler a certain
time, the most diligent tillage no longer affords them the
same returns as it did at first.

'*It it said, that Jethro Tull, who first proved the ad-
vantages of deepening and pulverizing soils, was neverthe-
less obliged at length to admit, that at each repetition of
the experiment the success was less decided, unless manure
were at the same time applied. Judicious tillage, in short,

" • See English Agricultural Journal^ No. 5, p. 32."

23*

270 APPENDIX TO PART I.

like the use of machinery in the arts, does not create any
new power, but only tends to render more available those
already latent in the earth.

"It was not therefore without reason, that Cato, after,
as we have seen, pronouncing, that the first, and the second
thing in agriculture, is to plough, adds, that the third is to
manure, for what is this but the art of providing for the in-
tended crop an adequate supply of those ingredients which
enter into its composition ?

"The principles therefore which have been laid down,
whilst they will serve to guide the husbandman in the se-
lection of his fertilizers, may also explain the different re-
sults that are obtained from the use of the same kind of
mineral manure in different soils.

" Among those which have excited the greatest interest
within the last few years, may be mentioned the nitrates of
potass, and of soda.

"The former, commonly called saltpetre, is produced
spontaneously in most parts of the world, and especially in
hot countries, in consequence of animal and vegetable
decomposition conducted under particular conditions, and
accordingly it has been introduced into agriculture from an
early period.*

"The latter, sometimes distinguished from its crystalline
form, as cubic nitre, is met with in large quantities in Peru,
fourteen leagues from the port of Iquicque, where, ac-
cording to Mr. Darwin,! ^^ forms a stratum two or three
feet thick, lying close beneath the surface, and following
the margin of a grand basin or plain, elevated 3300 feet
above the level of the Pacific, but which, nevertheless,
appears evidently to have been at one time a lake, or in-
land sea.

"The price of the salt at the ship's side in 1835, at the
time Mr. Darwin visited the spot, was fourteen shillings a
cwt., the grand item of expense being its transport to the
coast. J

K * Where the price operates as an objection to its use, the method
of forming artificial nitre-beds, by mixing together vegetable and ani-
mal matters in a state of decomposition with calcareous earth, may be
economically adopted. See Cuthbert Johnson, on Saltpetre and Ni-
trate of Soda, Ridgway, 1840."

" t See Darwin's Journal, in Voyage of the Beagle."
t Mr. J. H. Blake of Boston, who recently visited Peru, informs me,
that the cost of the nitrate of soda was ^ 2.50 per quintal, and that it
could be obtained here at from 4^ to 5 cents per lb. The crude nitrate,
containing from 70 to 80 per cent, of the pure salt, might be obtained
here at 2^ cents per lb. — fV.

PRACTICAL INFERENCES.

271

'* These particulars are perhaps not unimportant, as they
may serve to show that an almost unlimited supply of both
these salts may be calculated upon, and, in the case of the
nitrate of soda, that its price might be kept down, rather
than enhanced, by an increased demand.

**That, however, with which the agriculturist is most
concerned, is to determine the relative value of these salts
as manures, and to discriminate the kind of land to which
either or both are beneficial.

** Now, it is remarkable, that the nitrates, whilst they
have in some cases occasioned a wonderful increase of pro-
duce, in others have appeared of little service, and also
that, whereas on certain land both were equally efficacious,
on a different description of soil, the one has answered,
whilst the other failed.

*' For a great deal of interesting information on this sub-
ject, I may refer to the Journal of the Royal Agricultural
Society of England, — its last number* more especially:
on the present occasion I shall confine myself to noticing
the communication of Mr. Hyett, of Painswick, as one,
which probably points to the true cause of the advantage
derived from the employment of these salts.

**Mr. Hyett's experiments were made upon the stone or
cornbrash of Gloucestershire, a coarse and impure oolitic
limestone, which had been drilled with white Sicilian wheat
in the autumn.

** Nitrate of soda, at the rate of 1 cwt. to the acre, was
on the 21st of April, sown and hoed in over all the field,
excepting two square portions, which were staked out, and
left unnitrated.

'*0n the 16th of May the effect of the salt was per-
ceived, by the dark green color of the plants.

** The results of the harvest were as follows :

Produce.

Measure per acre.
Without nitrate. | With nitrate.

Value per acre.
Excess.

Corn clean . .
tail . . .

total . .

Bu. Pks. Pts.

30. 2. 11

2. 3. 11

Bu. Pks. Pts.

37. 3. 4

5. 3. 7

Bu. Pks. Pts.
7. 0. 9
2. 3. 12

33. 2. 6 1 43. 2. 11 ] 10. 0. 5

1 Weight. 1 Per acre. | |

Straw

T. Cwt. qrs. lbs.
1. 3. 1. 21

T. Cwt. qrs. lbs.
1. 11. 2. 3

T. Cwt. qrs. lbs.
0. 8. 0. 10

*'From these data Mr. Hyett calculates, that the in-
creased value of the produce, arising from the use of the

<«* For January, 1841."

272

APPENDIX TO PART I.

nitrate of soda, gives a profit of 2/. lis. 2d. per acre, after
deducting I/. 3s. Od. for the value of the salt employed.

**But not only does the nitrate increase the quantity of
the grain, but it tends to augment those ingredients, which
contain the largest amount of nitrogen, and consequently
afford the greatest degree of nutriment, namely, the gluten
and albumen.

**This is shown, by the analysis of the nitrated, and non-
nitrated wheat, made by a chemist at his request, the re-
sults of which were as follows :

Wheat on which the

Wheat on which no

nitrate was used, gave

Bran

25000

24-000

Gluten

23 250

19000

Starch

49-500

55-500

Albumen

1-375

•625

Extract

•375

•250

Loss and water . .

•5

•628

100- parts.

** Thus it is seen, that in the nitrated wheat there was
4*25 per cent, more gluten, and 0*75 more albumen, than
in the non-nitrated sample.

** Considering, then, that these constituents contain nearly
16 per cent, of nitrogen, we are justified perhaps in at-
tributing their increase to the decomposition of the nitric
acid present in the salt, and the consequent supply of nitro-
gen in greater abundance than is naturally present in the
soil.

*' And if such be the mode of its operation, it may be
possible to explain why these salts should appear so capri-
cious in their effects on the different kinds of land to which
they have been applied.

'' When the ground already contains all the other con-
stituents which the plant requires, as, for instance, a suffi-
cient amount of the earthy phosphates, and of silicate of
potass, the addition of the nitric salt will do good, by sup-
plying nitrogen, and thus enabling the vegetable to assimi-
late a proportionate quantity of the other ingredients.

"But when the latter are already nearly exhausted, the
addition of the nitrates will no ^longer be of advantage,
since only that portion of nitrogen can be assimilated
which is equivalent to the amount of the earthy phosphates,
of the silicate of potass, and of the other fixed ingredients,
which the plant obtains from the soil.

PRACTICAL INFERENCES. 273

** Hence, the proper remedy in such a case would seem
to be, that of applying some other manure, which may fur-
nish a due supply of the deficient matters.

'* Thus, if the nitrates have failed, we should be inclined
to try the next year the effect of phosphate of lime, or of
animal manure, upon the same soil.

*' But it seems to happen sometimes, that the same land,
which is benefited by the administration of one kind of nitric
salt, is scarcely affected by another.

*'This anomaly presented itself in an experiment on a
small scale, which was tried at my request, by my broth-
er, the Rev. E. Daubeny, on his farm, in the vicinity of
Cirencester.

"The subsoil is a stiff retentive clay, resting upon the
cornbrash limestone, and the farm, before it came into its
present occupation, was in an exhausted condition, though
it has latterly yielded somewhat better returns.

** A coarse analysis of a sample, conducted according to
the method recommended by Mr. Rham, in the Journal of
the English Agricultural Society,* afforded me the follow-
ing results :

" 1000 grains contained, 607, of impalpable powder, consisting of
Water . . . . .57

Humus . . . . .57

Silica . . . . .64

Alumina mixed in the silica . . 24

Oxide of iron . . . .19

Carbonate of lime ... 90

Magnesia .... a trace

Clay ..... 296

Total . . . . .607

And 388 of coarser materials, separated by
Sieve . . No. 1. the coarsest 117"^ consisting

Sieve . No. 2. . .151 chiefly of

Sieve . . No. 3. the finest 120 j^clay, with

[50 grs. of

Total . . . . . 388 j carbonate

Loss .... 5 J of lime.

**Four equal strips of this land, each somewhat ex-
ceeding J of an acre, and contiguous one to the other,
which had been sown with wheat in the autumn of 1839,
were measured out.

"The first of these, which lay next to the hedge, was
left without any addition of manure.

*'The second, adjoining, had a top-dressing of J cwt. of
nitrate of potass given it in April.

(( »

Number 1, page 46."

274 APPENDIX TO PART I.

*'The third portion was left, like the first, without
addition.

**The fourth, or that farthest from the hedge, had a
similar top-dressing of nitrate of soda applied at the same
period.

** The salts were respectively scattered over the strips
of land in as uniform a manner as possible, and became
diffused through the soil, by means of the showers which
followed shortly after their application.

*' As the wheat advanced towards maturity, the nitrated
patches were distinguishable, by the more vivid greenness
of the crop, and by its standing up somewhat above the
general level, but this difference was less perceptible at a
later stage of its progress.

'* In the autumn the whole was reaped as usual, and the
following results obtained :

** No. 1. produced only 5 bushels, 54 lbs. of grain, or 23
bushels, 36 lbs. to the acre, but the crop had been ac-
cidentally trodden by sheep, and much devoured by birds.
The straw was not weighed.

*'No. 2. produced 7 bushels, 51 lbs., or 31 bushels, 48
lbs. to the acre, and 520 lbs. of straw = 1 ton, 0 cwt. 80 lbs.
to the acre.

*'No. 3. produced 6 bushels, 54 lbs., or 27 bushels, 36
lbs. to the acre, and 421 lbs. of straw = 16 cwt. to the acre.

**No. 4. produced 6 bushels, 48 lbs., or 27 bushels,
12 lbs. to the acre, and 432 lbs. of straw = 15 cwt. 48 lbs.
to the acre.

'* With respect to weight, that of No. 2. was 62| lbs. to
the bushel, that of No. 3. and 4. was only 62 lbs.

**Now 3 J lbs. of flour from No. 3, produced of bread
4 lbs. 4 ozs.

'* Whereas 3J lbs. from No. 2. produced 4 lbs. 14 ozs.

'* Hence the difference, between the produce of the strip
of ground which had been manured with nitrate of potass,
and that which had received no manure, may be calculated
as follows :

'* Amount of produce, of
Bu. lbs.

''No. 3 6 54 = 6.

''No. 2 7 57 = 7.

" As 6 : 7 : : 100 : 120, or 20 per cent, of increase in the
amount of produce.

"To which add, that the quantity of flour, that in No.

PRACTICAL INFERENCES. 275

3 had produced 4 lbs. 4 ozs. of bread, in No. 2. produced

4 lbs. 14 ozs. Now

*' As 4 lbs. 4 ozs. : 4 lbs. 14 ozs. : : 100 : 1 14.

'* Showing an increase per cent, of 14 -j- 20 = 34 per
cent.

*'Now if we calculate the wheat as worth eight shillings
a bushel, the profit of using the nitrate of potass will stand
as follows :

*'27 bushels 36 lbs. at 8.s. = 11Z. value of the produce on
the non-nitrated land : add 34 per cent, or Jrd = 3/. 135.
4d., for the value of the nitrated, which, after deducting
1/. 10*. for the value of a cwt. of nitrate of potass, and for
carriage, will leave to the farmer a clear profit of 2/. 3s. 4d.

*' The superior absorbing power of the nitrated flour,
over the non-nitrated^ was found to depend upon the pres-
ence of a larger amount of gluten, for I discovered in the
former 740 grs. in the pound, or 13 per cent. ; in the latter
850 grs. in the pound, or 15 per cent, of that ingredient,
the difference being 2 per cent, in favor of the nitrated
wheat, a result which confirms, in a very satisfactory man-
ner, the statement of Mr. Hyett.*

**But how are we to account for the failure of the nitrate
of soda, on soil which had been so materially benefited by
the administration of nitrate of potass ^

**The small scale upon which the experiment was
conducted, may render us reluctant to build much upon
the results obtained, until it has been again repeated, but
supposing the fact to be hereafter confirmed, I can only
conjecture, that the diflference must have arisen from a
deficiency in the land, of potass, which would be supplied
by the saltpetre, but not by the nitrate of soda. | Should
this be the true solution, those soils, in which nitrate of soda
has succeeded, ought to contain a larger quantity of potass,
than those in which it has failed.

**The general principles laid down may also inform us,
as to the true plan upon which the succession of our crops
should be regulated.

** Those plants ought to succeed each other, which con-
tain different chemical ingredients, so that the quantities

" * The amount of gluten is smaller than in the samples reported on
by Mr. Hyett, but my gluten was dried, with the greatest care, under
the exhausted receiver of an air-pump, with sulphuric acid, till it
ceased to lose weight."

" t Nitrate of soda is stated to exist in barley, but it has not been de-
tected in wheat. It would therefore be worth while to see, whether
the above salt is particularly suited to the former crop."

276 APPENDIX TO PART I.

of each, which the soil at any given time contains, may be
absorbed in an equal ratio.

**Thus a productive crop of corn could not be obtained,
without the phosphates of lime and magnesia which are
present in the grain, nor without the silicate of potass which
gives stability to the stalks.

**It would be injudicious, therefore, to sow any plant
that required much of any of the above ingredients, imme-
diately after having diminished the amount of them present
in the soil, by a crop of wheat, or of any other kind of corn.

**But, on the other hand, leguminous plants, such as'
beans, are well calculated to succeed to crops of corn, be-
cause they contain no free alkalies, and less than one per
cent, of the phosphates.

** They thrive, therefore, even where these ingredients
have been withdrawn, and during their growth^ afford time
for the ground to obtain a fresh supply of them, by a fur-
ther disintegration of the subjacent rock.

*' For the same reason, wheat and tobacco may some-
times be reared in succession in a soil rich in potass, be-
cause the latter plant requires none of those phosphoric
salts which are present in wheat.

"In order, however, to proceed upon certain data, it would
be requisite, that an analysis of the plants most useful to
man should be accomplished in the different stages of their
growth, a labor which has hitherto been only partially un-
dertaken, and which perhaps is an object worthy to engage
the attention of a great Body, like that of the English Ag-
ricultural Association.

** It is a curious fact, that the same plant differs in con-
stitution when grown in different chmates. Thus in the
beet-root, nitre takes the place of sugar, when this plant is
cultivated in the warmer parts of France.*

"The explanation of this difference is probably as fol-
lows : —

"Beet-root contains, as an essential ingredient, not only
saccharine matter, but also nitrogen, and it is probable,
that the two are mutually so connected together in the veg-
etable tissue, that the one cannot exist without the other.
The nitrogen, being derived from the decomposition of am-
monia, must be affected by any cause which diminishes the
supply of the latter ; and in proportion as this ingredient
is wanting, the secretion of sugar will likewise fall off.

"Now, it has been shown by Liebig, that the formation

"* See Chaptal."

PRACTICAL INFERENCES. 277

of nitric acid is owing to the decomposition of ammonia,
and it is conceived by him, that the last products of the de-
composition of animal bodies present themselves, in the
form of ammonia in cold, and in that of nitric acid in warm
climates. * Hence, in proportion to the amount of nitric
acid formed, and of nitre absorbed by the plant, that of the
nitrogen, and consequently that of the saccharine matter,
present in it, may be diminished.

*'We may also be guided in the management and selec-
tion of manures, by the principles above laid down. The
solid excrement of animals varies of course in composition
according to the nature of their food : thus that of herbivo-
rous animals, which are fed principally on grasses, contains
much silicate of potass, as well as phosphoric salts, but
comparatively little nitrogen ; whilst human. faeces contain
little of the former ingredient, but much phosphate, and a
larger proportion of nitrogen. There will be seen even a
difference in these respects between the manure afforded by
the inhabitants of towns, fed principally upon animal food,
and that of peasants, who subsist in a greater degree upon
vegetables.

*'In like manner, the excrement of cattle is more effica-
cious as manure, when the animal is well fed, and under-
going the fatting process, than when it is more scantily
nourished.

'* According to Sprengel, there is a difference between
different kinds of herbivorous animals in this respect, cows

* " I have seen no attempt to account for the formation of nitrate of
soda in such large quantities in Peru, and may therefore offer the fol-
lowing, as at least a plausible solution.

*' Wherever salt lakes occur, which become partially or wholly dried
up during a part of the year, carbonate of soda will be formed from the
decomposition of common salt. This I have observed myself on the
sandy plains of Hungary, in the neighborhood of Pesth. Now if any
circumstances should concur in such spots, calculated to generate nitric
acid, the latter, by its stronger affinity for the alkali, would take the
place of the carbonic acid, and nitrate of soda would result.

" This, however, being a deliquescent salt, would not accumulate on
the surface, except in countries like Peru, remarkable for their extreme
dryness.

" But how are we to account for the generation of so large a quanti-
ty of nitric acid in this locality .''

" If we suppose with Mr. Darwin, that the district in which the salt
is found was once a lake or inland sea, its change to dry land must have
caused the destruction of all its marine inhabitants. Now the decom-
position of their exuviae would, in a warm climate, present themselves,
as stated in the text, in the form, rather of nitric acid, than of ammonia.

" Hence the production of so much nitrate of soda in Peru, is attrib-
utable to the heat ; its preservation to the dryness of the climate."

278 APPENDIX TO PART L

requiring, for the chemical constitution of their body, or
for the formation of their milk, more nitrogen, and more
phosphate of lime, than sheep ; whilst the latter require
again more sulphur, and more common salt, for the forma-
tion of their wool. Hence the excrements of oxen contain
less nitrogen than those of sheep, whilst they are more
abundant in salt and sulphur.

'* Accordingly it is found in practice, that sheep's dung
ferments more readily than that of black cattle. ' The
latter, therefore,' says Liebig, 'is of most service on soils
consisting of lime and sand, which contain no silicate of
potass or phosphates, whilst their value is much less when
applied to soils formed of argillaceous earth, basalt, gran-
ite, porphyry, clinkstone, and even mountain limestone,
because all these contain potass in considerable quantity.'

** Human excrements, on the contrary, are useful in
both descriptions of soil, but would be inadequate to supply
the silicate of potass which is wanting in the former.

**The constituents, however, to which the solid excre-
ments of animals in general owe their principal efficacy
are the earthy phosphates ; and hence we see, why it is
that animal manure should favor the growth of corn, which
contains so much phosphate of lime and magnesia, and
why the earth of bones, and even the ashes of certain
kinds of wood, such as the beech, which contain phos-
phates, may be advantageously substituted, whilst the ash-
es of others, as of the oak and fir, which are deficient in
the phosphates, are of very little avail.

" We see also the cause of the fertilizing quality of
liquid manure, as employed in Holland, for those crops
which are most subservient to the nourishment of man.

*' Liquid manure consists in a great degree of the urine
of various animals, which, during its decomposition, exhales
a larger quantity of ammonia than any other species of
excrement.

" Now all kinds of corn contain nitrogen, and conse-
quently any manure which yields a ready supply of ammo-
nia, must cause a fuller development of those parts of the
plant which are of the greatest use to man.

*'Even the kind of animal manure usually employed in
this country owes its efficacy, so far as it is dependent
upon the ammonia present, to the urine, rather than to the
solid excrement, of which it is made up, and hence be-
comes materially deteriorated in this respect, when the
more liquid portions are allowed to drain off from it.

PRACTICAL INFERENCES. 279

**We may also derive from these considerations, some
useful cautions, as to the treatment of this same material.

*' Ammonia, in the free or uncombined condition in which
it is generated from the decomposition of animal substances,
is caustic and noxious to vegetation, and is likewise so
volatile that it will escape into the atmosphere so soon as
it is produced, unless some means are taken to detain it.

*'This causticity is readily removed by promoting its
combination with the carbonic acid of the atmosphere, but
to prevent its escape during the time necessary for effect-
ing this union, various expedients have been resorted to.

*' Where water in sufficient quantity is present, along
with the other materials of the dung-heap, this alone will
in some measure tend to prevent its volatilization, and the
same object is further secured, by admixture with peat, as
recommended by Lord Meadowbank, or with sawdust,
tanner's bark, turf, and other similar substances. These
too are beneficial, not only by moderating the putrefactive
process, but also by detaining the ammonia generated
within their pores, and thus preventing its loss.

"The advantage of compost heaps, which are strongly
advocated by some farmers, depends mainly on these prin-
ciples.

*'The method recommended by a writer, in a late num-
ber of the English Agricultural Journal,* to whom a prize
of ten sovereigns was awarded for his Essay, consisted, in
first making a substratum of peat |ths, and sawdust Jth ;
spreading over it the dung from the cattle-sheds, and the
urine preserved for the purpose in tanks contiguous ; and
then, after allowing the mixture to remain exposed for a
week, covering it with a fresh layer, nine inches or a foot
thick, of peat and sawdust, or of peat alone.

** Several such alternations of peat and manure are to
be piled one above the other during the winter, great care
being always taken, that the peat should be as dry as pos-
sible, by exposing it previously for several months to the
weather.

*'Now it will be immediately perceived, that these
recommendations of a practical farmer completely fulfil
the conditions, which theory suggests, for making the best
use of our manure, by first neutralizing the ammonia, and
afterwards detaining it within the pores of a spongy sub-
stance, until it is spread over the land.

"The most eflfectual plan, however, of preventing its

"* Part II p. 135."

280 APPENDIX TO PART I.

loss, would seem to be, not to wait for the slower action
of carbonic acid upon it, but to combine it directly with
those acids, which form with it salts fixed at common tem-
peratures.

** Hence, Liebig advises the addition of sulphuric or of
muriatic acid, both cheap substances, to the other materials
of the dung-heap, which, forming with the ammonia pres-
ent, the sulphates and muriates of that alkali, would at
once prevent any loss of it by evaporation.

*' If these expedients be not adopted, it should at least be
borne in mind, that unless means are taken to prevent it,,
the most valuable portion of the manure is constantly
escaping, during exposure to air and sun, by evaporation,
and also by draining off into the ground, whence, instead
of a material calculated to afford a ready supply of nitro-
gen to the plant, we obtain an effete mass, in which that
element is in a great measure wanting, and which, there-
fore, can only influence the growth of plants, by virtue of
the phosphoric salts and other fixed ingredients still pres-
ent in it.

*' These views also throw some new light upon the use
of gypsum, or sulphate of lime, as a manure to certain
crops.

*' The fact, that leguminous plants contain this substance
as an essential ingredient, may in some measure explain
its fertilizing effect on them, but it is also found serviceable
to turnips and cabbages, which do not appear to contain it,
nor does it seem easy thus to explain the superior advan-
tage said to arise, from scattering it in fine powder over
the leaves of clover and saintfoin, as is practised in France
and in North America, and with such manifest good effect,
that, it is said, if the substance be partially applied to a
field, the portions that have received this dressing may
afterwards be distinguished from the rest by the superior
luxuriance of the crop.

''Liebig, therefore, has suggested another mode in
which gypsum may be beneficial to crops in general, by
reference to the property which it possesses, of depriving
ammonia of its volatility, and thus preventing its escape
into the atmosphere.

*'This effect arises from the double decomposition which
takes place, when sulphate of lime and carbonate of ammo-
nia are brought together, the lime being converted into a
carbonate, and the ammonia uniting with sulphuric acid.

' ' The above theory of its use being admitted, we may

PRACTICAL INFERENCES. 281

be encouraged to extend its application to other crops
besides the Leguminosae, and also to mix it with the dung
of our stables, so as to prevent the waste of this valuable
material, which is constantly occurring. (See p. 191.)

" But the farmer must be reminded, that it will be neces-
sary, that the sulphate of ammonia resulting from the
action of the gypsum, should be brought into contact with
some substance capable of slowly decomposing it, so as to
supply ammonia to the plant.

"For there is no reason to believe, that the organs of a
vegetable can decompose sulphate of ammonia, and if they
were able so to do, the disengagement of free sulphuric
acid in consequence could hardly fail to be injurious to
their structure.

**Now a soil consisting of pure sand, or of clay, would
be incapable of acting upon this salt, but contradictory as
it may seem to the fact, that carbonate of ammonia is
decomposed by sulphate of lime, carbonate of lime does
appear in a slight degree to disengage ammonia even in
the cold, as may be seen by the change of color produced
in a piece of turmeric or reddened litmus paper, placed
over a vessel containing powdered chalk, as soon as it is
moistened with a solution of sulphate of ammonia.

**And since this interchange of constituents is effected
rapidly under the influence of a high temperature, as hap-
pens in the common method of obtaining carbonate of
ammonia artificially by double decomposition, it is worth
inquiry, whether it may not be favored likewise by exposure
to solar heat and light.

** Where calcareous matter, therefore, exists in the soil,
ammonia may be slowly supplied in this manner to the
growing plant, and it is possible even, that the carbonate
of lime, which seems to be generally present in the sap,
may act in the same manner.

'*In this ^yay we may readily explain the use of scatter-
ing gypsum over the leaves of clover shortly before a
shower of rain. The ammonia present in the latter is thus
detained, and converted into sulphate by the action of the
gypsum upon it, and when introduced into the system by
the absorbing surfaces of the plant, it may be again con-
verted into carbonate, by the slow action of the carbonate
of lime present in the sap.

*' When, however, a more rapid disengagement of am-
moniacal gas is required for the nutrition of the intended
crop, we ought not to trust to the slow action of carbonate

24*

282 APPENDIX TO PART I.

of lime, but should apply quicklime to the spots over which
the manure has been scattered.

**It is probably in part by setting at liberty the volatile
alkali imprisoned in the soil, that quicklime acts so bene-
ficially in agriculture, and in particular, that it improves
soil containing a free acid, such as peat earth ; for, inde-
pendently of its use in neutralizing a substance, which
checks vegetation by its antiseptic properties, quicklime
may also disengage a portion of ammonia combined with
this acid, and thus afford to the plant a more abundant
supply of the nitrogen, which it requires.

"Chloride of calcium, common salt, sulphuric and mu-
riatic acids, phosphate of lime, and other salts, may, it
would seem, on the principles laid down, be substituted,
when gypsum cannot be obtained.

**The chlorides, indeed, like certain oxides, (such as
water and carbonic acid,) seem to be decomposed by the
plant under the influence of light, for chlorine is exhaled
by vegetables near the sea, as oxygen is in other situations.
Hence, if muriate of ammonia should result from the
action of common salt upon the carbonat^e of ammonia
present in rain, it may undergo decomposition when ab-
sorbed by the plant, and contribute in consequence to sup-
ply it with nitrogen.

*'The above considerations may suggest to us the utility
in agriculture of ammoniacal compounds of all kinds, as
substitutes for animal manure.

''Sal ammoniac is probably too expensive an article to
be employed ; but sulphate of ammonia may be had of the
wholesale chemist at a price considerably more reasonable,
namely, at 22/. per ton ; and the ammoniacal liquor, which
is afforded in abundance by our gas manufactories, through
the distillation of coal, is a still cheaper commodity.

*'The latter consists principally of carbonate of ammo-
nia, mixed with a certain proportion of the hydro-sulphuret,
and, until its use in agriculture was discovered, much of it
was allowed to run waste into the Thames, where its nox-
ious qualities destroyed the fish, and rendered the water
unpalatable and disgusting.

" Its efficacy as a manure is vouched for by many who
have made trial of it upon their land,* and although the
hydro-sulphuret of ammonia in a concentrated form would
doubtless be fatal to vegetation, yet in a proper state of

" * See a communication by Mr. Paynter, on Gas-water as a Manure,
Eng. Agricult. Journ. No. 1, p. 4."

PRACTICAL INFERENCES. 283

dilution it may be of service to certain crops, not merely
by virtue of the ammonia, but also in consequence of the
sulphuretted hydrogen, which it contains, since the latter
is found to be an ingredient in the turnip, and in some
other tribes of cruciferous plants.

"Where, however, it is found troublesome to preserve,
or difficult to convey to a distance this volatile material, an
easy method presents itself for retaining for any length of
time the ammonia present in it.

"This is done, by availing ourselves of the same prin-
ciple which has been already explained to you, in treating
of the uses of gypsum as a manure ; for as the gas liquor
consists of ammonia, combined principally with carbonic
acid, it is evident, that it may be converted into a sulphate
by admixture with sulphate of lime.

"lam indebted to an excellent scientific chemist* for
the following details, which may be of use to the agricul-
turist in enabling him to appreciate the importance of this
commodity, and to prepare for himself any quantity that he
may require for his farm.

"One gallon of the ammoniacal liquor added to 1 lb. 2-|
ozs. of powdered but not calcined gypsum, will produce
1 lb. of crystallized sulphate of ammonia. To effect the
decomposition, the materials should be mixed and stirred
up together for ten or twelve hours, a heat, below that of
ebullition, being at the same time employed. The sulphate
of ammonia remains in solution, and may be obtained in a
solid state, by evaporating at a low temperature.

"Theory would suggest, that this material ought to sup-
ply nitrogen to the crop at a much cheaper rate than the
nitrates employed for that purpose. For let us suppose,
that the farmer wishes to add to his land 60 lbs. of crys-
tallized sulphate of ammonia. This may be obtained by
introducing about 70 lbs. of powdered gypsum uncalcined
into 50 gallons of ammoniacal liquor ; for my informant
found, that one gallon mixed with chloride of calcium
yielded 4800 grs. of carbonate of lime, equivalent to about
7200 grs. of crystallized sulphate of ammonia, or 1 lb. 3
ozs. Now 4800 grs. of carbonate of lime are equivalent
to 8250 grs., or to 1 lb. 5 ozs. of sulphate of lime, with 2
atoms of water.

"This, therefore, is the quantity of gypsum required, to

" * Mr. Richard Phillips, the superintendent of the chemical depart-
ment of the establishment, connected with the Museum of Economic
Geology, lately instituted by government."

284 APPENDIX TO PART I.

convert the contents of 1 gallon of gas liquor into sulphate
of ammonia, and accordingly, 50 gallons will require 70
lbs. of gypsum, and will produce about 60 lbs. of the am-
moniacal sulphate.

**Now since the price per ton of gypsum is from 2Z. to
3/., the cost of 70 lbs. of it cannot exceed 2»., and the
labor of mixing the materials may be reckoned at about as
much more ; so that to a gas company, where this liquor,
not being employed for manufacturing any of the salts of
ammonia, has hitherto been regarded as so much refuse,
and where the heat requisite for evaporating and crystal-
lizing the product can be obtained with scarcely any in-
creased expenditure, the cost of the impure sulphate would
not exceed one penny per pound.

'* This then is less than half the cost of an equal quantity
of nitrate of soda, which at its present price (235. per
cwt.) may be reckoned at two-pence-halfpenny a pound,
and yet it may be shown, that a given weight of sulphate
of ammonia contains more ammonia, and consequently
ought to yield more nitrogen, than nitrate of soda.*

" Sulphate of ammonia 75 pis. contain of ammonia 17 = nitrogen 14.

whilst
Nitrate of soda .... 86 pts 17= 14.

**So far as theory goes, therefore, the balance would
seem to be in favor of the efficiency of sulphate of am-
monia over nitrate of soda, in the proportion of 15 to 86.

''These considerations are merely offered, by way of
encouragement to those who may be disposed to make trial
of this promising kind of manure, and of course will go
for little until they have been tested by experiment.

''There are other materials also employed as manure,
which appear to owe their efficacy to the presence of am-
monia, — such, for example, as soot, which contains a con-
siderable proportion of this principle united with carbonic
acid, and which accordingly has for a long time been ad-
vantageously employed as a top-dressing to land.

"Lastly, the foregoing considerations point out the de-
cided superiority of human to other sorts of animal manure.

" Independently of its being richer in most of those in-
gredients on which the fertilizing property of manure de-
pends, the following circumstance gives it an advantage.

" * Nitrate of potass ought to contain ten per cent, less nitric acid
than nitrate of soda, but, as it is a less deliquescent salt, the diiFerence
between the two, as obtained in commerce, is not very considerable."

PRACTICAL INFERENCES. 285

** When the excrements of the horse or ox are employed,
we are obliged to allow of their undergoing a long previous
process of fermentation, by which a large proportion of their
valuable matter is got rid of, in order, as much as possible,
to destroy the vitality of the seeds, which pass undigested
along with the faeces. And after all many still remain,
and are thus introduced into the fields when the manure is
scattered over them.

**By the use of night-soil we avoid this inconvenience,
and hence it is, that in China, where it is exclusively em-
ployed, the corn-fields are remarkably exempt from weeds.

** Chemistry has suggested means for destroying those
offensive qualities which have hitherto limited the use of
this species of manure, although it is stated by Liebig,
that the method adopted for that purpose on the Continent
is defective, inasmuch as a large proportion of their am-
moniacal contents is allowed to escape.

**Even under its present management, however, the pro-
cess may be regarded as one of the most important pres-
ents which chemistry has yet made to the practical farmer,
by rendering the accumulated filth of a large capital avail-
able for his purposes, in the remotest corner of the British
empire."

Professor Daubeny concludes his lecture with some high-
ly ingenious speculations on the primary source of the
carbon and nitrogen present in plants and animals. He
does not deem it probable that a quantity of organic
matter was called into existence at once, sufficient to sup-
ply the whole of the succeeding races of plants and ani-
mals with these ingredients ; or that the whole, which is
now condensed in the organization of the animal and vege-
table kingdoms, was at any one time present in the atmo-
sphere ; but that the carbon and nitrogen of plants was
originally supplied from the interior of the earth by vol-
canos. The fertility of the neighborhood of Naples Dr.
D. attributes to volcanic exhalations.

"Once grant," he continues, '* with Liebig, that the
nitrogen, which plants possess, can only be obtained by
them through the decomposition of ammonia, and it will
follow, that unless this gas be supplied from the interior of
the globe, the quantity of organic matter, into which this
principle enters as a component part, will be undergoing
a continual diminution.

*'For we know of no natural processes taking place on
the surface of the globe, which generate ammonia, ex-

286 APPExNDIX TO PART I.

cepting those connected with animal and vegetable decompo-
sition ; whilst there are many, such as the combustion of
various organic substances, which, by resolving bodies
containing nitrogen into their constituent elements, would
have diminished the aggregate amount of them which might
have formerly existed.

" Some compensating process, therefore, is clearly re-
quired, and that, if I mistake not, is the disengagement of
ammoniacal gas from the interior of the globe."

''Granting, then, what upon Liebig's principles seems
most consistent with analogy, namely, that the ammonia,
no less than the carbonic acid, which formed the food of
the first plants, has been produced, not by processes of ani-
mal decay, but by such as were proceeding within the globe
prior to the creation of living beings, the notion of a slow
and continuous disengagement of both compounds, from the
earliest period to the present time, will be received perhaps,
as at least the most probable mode of accounting for their
unfailing supply.

*' Whilst it relieves us from the difficulty of supposing the
atmosphere surcharged with these gases at any one period,
it suggests to us, at the same time, sublime and interesting
views of the arrangements of the Deity, in thus having made
all things subservient to one common end, and having or-
dained, that the mighty agents of destruction, which exist
in the bowels of the earth, should minister, like the malig-
nant Genii of some eastern fable, to the wants and necessities
of the living beings, which He has placed upon its surface."

USE OF PHOSPHATE OF SODA IN CALICO PRINTING.*

(See page 186.)

The discovery of the principle which led to the use of
phosphate of soda, was made in the United States, by Dr.
Dana, of Lowell. The first practical application of the
salt was made, in consequence of Dr. Dana's researches,
by Mr. J. D. Prince, Jr., at the works of the Merrimack
Manufacturing Company in Lowell, in 1834. Mr. J. D.
Prince, Sen., the scientific and accomplished superintend-
ent of the establishment, was engaged with Dr. Dana for a

* Substance of a comrauQication from Dr. Dana.

DANIELL'S ARTIFICIAL MANURE. 287

series of years on this subject. In 1839, Mr. Prince, Jr.
carried the process to England, and, with Mr. J. Mercer and
Blyth, took out letters patent. Mr. Prince sold his right to
Messrs. Mercer and Blyth, who introduced the process into
the establishments on the Continent. The article is now
made by M. Kestner, of Thann, who observes, in his letter
to the '*Societe Industrielle de Mulhouse," accompanying
a sample, and on which their committee reported. Bulletin
No. 63, that "the article is the invention of Messrs. Mercer
and Blyth, printers of calicoes near Manchester."

Dr. Liebig probably derived his knowledge of this im-
provement from the Bulletin referred to above, and his
statement is only partial respecting the effects of cow-dung.
The discovery of the principle of its action has led to the
employment of other salts, which produce effects equally
good as phosphates.

daniell's artificial manure.*

The basis of this manure is wood reduced to powder,
sawdust, which is to be thoroughly saturated with bituminous
and animal matters of all or any kind ; to this is to be
added small proportions of soda and quicklime. The
sample exhibited to the Royal Agricultural Society, was a
coarse black powder, having a strong smell, somewhat
resembling coal tar. In England its price will be about
one third that of bone dust. It is a kind of artificial
bituminous coal. It should be buried two or three
inches under the surface of the soil. For grass land,
it is to be well mixed with a considerable portion of
ordinary unvalued mould. The quantity to be used will
vary with the crop. About twenty-four bushels per acre
are recommended for wheat, and half as much more,
or thirty-six bushels, may be carefully applied for turnips
or mangel-wurtzel. Its direct effect is thought to be the
conveyance to the soil of the direct nutriment of future
growth. This effect is produced by the supply of ammo-
nia to the soil in substances calculated to retain it for a
time, — to again absorb it from the atmosphere, — as they
give it out to plants during their growth. It will probably
prevent also the ravages of insects.

* Abridged from notices in the New Genesee Farmer, Vol. III., by
J. E. T. ,

PART II.

OF THE CHEMICAL PROCESSES OF FERMENTATION,
DECAY, AND PUTREFACTION.

CHAPTER I.

CHEMICAL TRANSFORMATIONS.

Woody fibre, sugar, gum, and all such organic
compounds, suffer certain changes when in contact
with other bodies ; that is, they suffer decomposition.

There are two distinct modes in which these de-
compositions take place in organic chemistry.

When a substance composed of two compound
bodies, crystallized oxalic acid for example, is brought
in contact with concentrated sulphuric acid, a com-
plete decomposition is effected upon the application
of a gentle heat. Now crystallized oxalic acid is a
combination of water with the anhydrous acid ; but
concentrated sulphuric acid possesses a much greater
affinity for water than oxalic acid, so that it attracts
all the water of crystallization from that substance.
In consequence of this abstraction of the water, an-
hydrous oxalic acid is set free ; but as this acid can-
not exist in a free state, a division of its constitu-
ents 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

25 #*

290 CHEMICAL TRANSFORMATIONS.

the component parts of water, the remaining ele-
ments enter into a new form ; in place of oxalic acid,
we have its elements 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 ni-
trate of potash together, nitric acid is separated ia
consequence of the affinity of sulphuric acid for pot-
ash ; 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 com-
ponent 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 w^ood, for example, and moist-
en it with sulphuric acid ; after a short time the wood
is carbonized, while the sulphuric acid remains un-
changed, with the exception of its being united with
more water than it possessed before. Now this wa-
ter 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 wa-
ter, they were in a certain measure compelled to
unite in this form ; and in consequence of this, the
carbon of wood was separated as charcoal.

Hydrocyanic acid* and water, in contact with hy-
drochloric acid,t are mutually decomposed. The
nitrogen of the hydrocyanic acid, and a certain quan-
tity of the hydrogen of the water, unite together and
form ammonia; whilst the carbon and hydrogen of
the hydrocyanic acid combine with the oxygen of the
water, and form formic acid. { The ammonia com-

* See page 70, note.

t Formerly called Muriatic Acid, obtained from sea salt and compos*
ed of Hydrogen and Chlorine in equal vols. H -j- CI.
X See page 70.

EXAMPLES. 291

bines with the muriatic acid. Here the contact of
muriatic acid with water and hydrocyanic acid caus-
es a disturbance in the attraction of the elements of
both compounds, in consequence of which they ar-
range themselves into new combinations, one of
which, — ammonia, — possesses the power of uniting
with the acting body.

Inorganic chemistry can present instances analo-
gous to this iclass 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 enter
into combination with the body which determines the
decomposition. In cases of this kind a disturbance
is produced in the mutual attraction of the elements
of a compound, and they in consequence arrange
themselves into one or several new combinations,
which are incapable of suffering further change under
the same conditions.

When, by means of the chemical affinity of a sec-
ond 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 chem-
ical transformations, that none of the elements of the
body decomposed are singly set at liberty.

The changes, which are designated by the terms
fermentation, decay, and putrefaction, are chemical
transformations effected by an agency which has
hitherto escaped attention, but the existence of
which will be proved in the following pages.

292 CHEMICAL TRANSFORMATIONS.

CHAPTER 11.

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 of decomposi-
tion 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 long-
er reflects light (black spongy platinum). But an
alloy of silver and platinum dissolves with great ease
in nitric acid; the oxidation which the silver suffers,
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 cop-
per, 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 chemi-
cal affinity is the last. In the other cases, electrical

* An essential distinction is drawn in the following part of the work,
between decay and 'putrefaction {Verwesung und Fdvlniss)^ and they are
shown to depend on different causes ; but as the word decay is not gen-
erally applied to a distinct species of decomposition, and does not indi-
cate its true nature, I shall in future, at the suggestion of the author,
employ the term eremacausis, the meaning of which has been already
explained. — Ed.

THEIR CAUSES. 293

action ought to have retarded or prevented the oxi-
dation of the platinum or copper while they were in
contact with silver or zinc, but, as experience shows,
the influence of the opposite electrical conditions is
more than counterbalanced by chemical actions.

The same phenomena are seen in a less dubious
form in compounds, the elements of w^hich are held
together only by a feeble affinity. It is well known,
that there are chemical compounds of so unstable a
nature, that changes in temperature and electrical
condition, or even simple mechanical friction, or con-
tact with bodies of apparently totally indifferent na-
tures, cause such a disturbance in the attraction of
their constituents, that the latter enter into new
forms, without any of them combining with the act-
ing 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 increase of tem-
perature, the elements of hypochlorous acid* sep-
arate 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 con-
tact 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
decomposition of these bodies should be ascribed to
a peculiar power, different 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 decom-
position. These substances have always been viewed
as chemical compounds 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 inerticn^

* Formerly, protoxide of chlorine.

25*

294 CHEMICAL TRANSFORMATIONS. M

and any shock or movement is sufficient to destroy
the attraction of their component parts, and conse-
quently their existence in their definite form.

Peroxide of hydrogen* belongs to this class of
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 con-
stituents. In this respect, its decomposition depends
evidently upon the same causes which effect that of
iodide of nitrogen, or fulminating silver. Yet it is
singular, that the cause of the sudden separation of
the component parts of peroxide of hydrogen has
been viewed as different from those of common de-
composition, and has been ascribed to a new power
termed the catalytic force. Now, it has not been con-
sidered, that the presence of the platinum and silver
serves here only to accelerate the decomposition ;
for without the contact of these metals, the peroxide
of hydrogen decomposes spontaneously, although
very slowly. The sudden separation of the constit-
uents of peroxide of hydrogen differs from the de-
composition of gaseous hypochlorous acid, or solid
iodide of nitrogen, only in so far as the decomposi-
tion takes place in a liquid.

A remarkable action of peroxide of hydrogen has
attracted much attention, because it differs from
ordinary chemical phenomena. This is the reduction
which certain oxides suffer by contact with this sub-
stance, 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 retained merely by a feeble affinity,
such as the oxides of silver and of gold, and perox-
ide of lead.

Now, other oxides, which are very stable in com-
position, effect the decomposition of peroxide of hy-

* A remarkable compound, consisting of 1 Hydrogen, and 2 Oxygen.
See description and process for obtaining; in Webster's Chemistry f
p. 134.

THEIR CAUSE. 295

drogen, 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 oxy-
gen escapes as a gas. Peroxide of manganese may
in the same manner be reduced to the protoxide, and
ogygen 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. If, for ex-
ample, we add to peroxide of hydrogen sulphuric
acid, and then peroxide of manganese in the state of
fine powder, much more oxygen is evolved than the
compound of oxygen and hydrogen could yield ; and
if we examine the solution which remains, we find a
salt of the protoxide of manganese, so that half of
the oxygen has been evolved from the peroxide of
that metal.

A similar phenomenon occurs, when carbonate of
silver is treated with several organic acids. Pyruvic
acid, for example, combines readily with pure oxide
of silver, and forms a salt of sparing solubility in
water. But when this acid is brought in contact
with carbonate of silver, the oxygen of part of the
oxide escapes with the carbonic acid, and metal-
lic silver remains in the state of a black powder.
(Berzelius.)

Now no other explanation of these phenomena
can be given, than that a body in the act of com-
bination or decomposition enables another body, with
which it is in contact, to enter into the same state.
It is evident that the active state 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 under-

* A peroxide is one that contains the largest proportion of oxygen.
When several compounds of metals and oxygen occur, that which con-
tains the smallest proportion of oxygen is called the first or protoxide.

296 CHEMICAL TRANSFORMATIONS.

go that change; and combinations and decompo-
sitions 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 trans-
formations 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 of combustion exercises upon a combustible body
in its vicinity ; with this difference only, that the
causes which determine the participation and dura-
tion of these conditions are different. For the cause,
in the case of the combustible body, is heat, which
is generated every moment anew ; whilst in the phe-
nomena of decomposition and combination which we
are considering at present, the cause is a body in
the state of chemical action, which exerts the de-
composing 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 they 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 move-
ment, the whole liquid becomes suddenly solid while
heat is evolved. The same phenomenon happens
with water, for this liquid may be cooled much under
32^ F. (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 inertim so as to ar-
range themselves into certain forms. A dilute solution
of a salt of potash mixed with tartaric acid yields no
precipitate whilst at rest ; but if motion is communi-
cated to the solution by agitating it briskly, solid
crystals of cream of tartar are deposited. A solu-

FERMENTATION AND PUTREFACTION. 297

tion of a salt of magnesia, also, which is not rendered
turbid by the addition of phosphate of ammonia, de-
posits the phosphate of magnesia and ammonia on
those parts of the vessel touched with the rod em-
ployed in stirring.

In the processes of combination and decompo-
sition under consideration, motion, by overcoming
the vis inerticB, gives rise immediately to another
arrangement 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 cer-
tain order, otherwise both friction and motion would
be without the smallest influence.

The simple permanence in position of the atoms
of a body, is the reason that so many compounds ap-
pear 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 rapid-
ly, are transparent, of a conchoidal fracture, and
elastic and flexible to a certain degree. But the
former becomes dull and opaque 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, opaque, and so hard as to strike
fire with steel. Now, in both these bodies, the com-
pound 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

298 CHEMICAL TRANSFORMATIONS.

cause ; a fact which shows, that their molecules have
assumed another position, and that they possess,
therefore, a certain degree 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 compo-
sition as calcareous spar, but of which the hardness
and crystalline form prove that its molecules are
arranged in a different manner. When a crystal of
arragonite is heated, an interior motion of its mole-
cules is caused by the expansion ; the permanence
of their arrangement is destroyed ; and the crystal
splinters 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 the equilibrium, in con-
sequence of which the particles of the body put in
motion obey other affinities 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 condition in many bodies, it cannot be doubted
that a body in the act of combination or decompo-
sition 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 com-
binations, or suffer decompositions.

The reality of this influence has been already suffi-
ciently proved by the facts derived from inorganic
chemistry, but it is of much more frequent occurrence
in the relations of organic matter, and causes very
striking and wonderful phenomena.

By the terms fermentation y putrefaction, and erema^
causiSy are meant those changes in form and prop-
erties which compound organic substances undergo
when separated from the organism, and exposed to
the influence of water and a certain temperature.
Fermentation and putrefaction are examples of that

FERMENTATION AND PUTREFACTION. 299

kind of decomposition, which we have named trans-
formations : the elements of the bodies capable of
undergoing these changes arrange themselves into
new combinations, in which the constituents of water
generally take a part.

Eremacansis (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 uni-
formly evolved, and occasionally even light. In the
processes of decomposition 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 without odor, are now, by pretty
general consent, designated by the term fermenta-
tion; 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 putrefac-
tion are processes of decomposition of a similar kind,
the one of substances destitute of nitrogen, the oth-
er of substances which contain it.

It has also been customary to distinguish from
fermentation and putrefaction a particular class of
transformations, 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 them-
selves are purely accidental ; there is, therefore, no
reason for the distinction just mentioned.

298 CHEMICAL TRANSFORMATIONS.

By the iitvms fermentation y putrefaction^ and erema-
causis, are meant those changes in form and prop-
erties which compound organic substances undergo
when separated from the organism, and exposed to
the influence of water and a certain temperature.
Fermentation and putrefaction are examples of that

FERMENTATION AND PUTREFACTION. 299

The transformations of those matters which evolve
gaseous products without odor, are now, by pretty
general consent, designated by the term fermenta-
Hon; 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 putrefac-
tion are processes of decomposition of a similar kind,
the one of substances destitute of nitrogen, the oth-
er of substances which contain it.

300 CHEMICAL TRANSFOKMATIONS.

CHAPTER III.

FERMENTATION AND PUTREFACTION.

Several bodies appear to enter spontaneously into
the states of fermentation and putrefaction, particu-
larly such as contain nitrogen or azotized substan-
ces. N0W5 it is very remarkable, that very small-
quantities of these substances, in a state of fermenta-
tion or putrefaction, possess the power of causing
unlimited quantities of similar matters 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 fer-
ment, 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 condition when in contact with them.

These changes evidently differ from the class of
common decompositions which are effected by chem-
ical affinity ; they are chemical actions, conversions,
or decompositions, excited by contact with bodies
already in the same condition. In order to form a
clear idea of these processes, analogous and less
complicated phenomena must previously be studied.

The compound nature of the molecules of an or-
ganic 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 another is inversely propor-
tional to the number of simple atoms in the com-
pound molecule. Thus, protoxide of manganese by
absorption of oxygen is converted into the sesqui-
oxide, the peroxide, manganic, and hypermanganic

OF ORGANIC COMPOUNDS. 301

acids, the number of atoms of oxygen being aug-
mented by I, by 1, by 2, and by 5. But all the
oxygen contained in these compounds, beyond that
which belongs to the protoxide, is bound to the
manganese by a much morfe feeble affinity ; a red
heat causes an evolution of oxygen from the per-
oxide, and the manganic and hypermanganic acids
cannot be separated from their bases without under-
going immediate decomposition.

There are many facts which prove, that the most
simple inorganic compounds are also the most stable,
and undergo decomposition with the greatest diffi-
culty, whilst those which are of a complex composi-
tion 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 the
infinite divisibility of matter in general, the exist-
ence 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 compound atoms. The properties of
these compound atoms differ in organic nature, not
only according to the form, but also in many instan-
ces according to the direction and place, which the
simple atoms take in the compound molecules.

When we compare the composition of organic
compounds with inorganic, we are quite amazed at
the existence of combinations, in one single molecule
of which, ninety or several hundred atoms or equiv-
alents 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
26 .

302 CHEMICAL TRANSFORMATIONS.

of sugar 36, 1 of amygdalin 90, and 1 of stearic
acid 138 equivalents. The component parts of
animal bodies are infinitely more complex even than
these.

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 temperatures volatile com-
pounds 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 coirf][)lex 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 remove a part or all of it, or
replace one of the constituents of the compound by
another substance. But w^e cannot produce a differ-
ent 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 com-
pound of ether with alcohol or of formic acid with
sachulmin.f Indeed, we may calculate almost all
the known organic compounds destitute of nitrogen

* S denotes sulphur, K (Kali) potash, O oxygen, 4 the number of
atoms. When no number is used, one atom is understood.

i The black precipitate obtained by the action of hydrochloric acid
on sugar.

OF ORGANIC COMPOUNDS- 303

I from sugar, by simply adding the elements of water,
I or by replacing any one of its elementary constitu-
! ents by a different substance. The elements neces-
sary to form these compounds are, therefore, con-
tained 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 under-
goes when brought into contact with other bodies
which exercise a marked influence upon it, we find,
that these changes are not confined to any narrow
limits, 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 constitu-
ent of the body, which it decomposes, by virtue of
its affinity for that constituent, and never resigns its
proper chemical character, in whatever form it may
be applied. But when it acts upon sugar, and
induces great changes in that compound, it does
this not by any 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 themselves. Muriatic and sulphuric acids,
which differ so much from one another both in char-
acters and composition, 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
differences 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,
both of them containing carbon and the elements of
water. Again, when sugar is subjected to the action
of alkalies, a whole series of different new products
is obtained ; while oxidizing agents, such as nitric

304 CHEMICAL TRANSFORMATIONS

acid, produce 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 resistance 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 exist only by the vis-
inerticB of their elements. Its elements 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, com-
binations, therefore, which possess a very complex
molecule, which are capable of undergoing the de-
compositions named fermentation and putrefaction.

We have seen that metals acquire a power, which
they do not of themselves possess, namely, that of
decomposing water and nitric acid, by simple con-
tact with other metals in the act of chemical combi-
nation. We have also seen, that peroxide of hydro-
gen 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 de-
composition, although they exert no chemical affinity
or attraction for them or their constituents. The
cause which produces these phenomena will be also
recognised, by attentive observation, in those matters
which excite fermentation or putrefaction. All bod-
ies in the act of combination or decomposition have
the property of inducing those processes ; or, in
other words, of causing a disturbance of the statical
equilibrium in the attractions of the elements of
complex organic molecules, in consequence of which

OF BODIES WHICH DO NOT CONTAIN NITROGEN. 305

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 char-
acters of the bodies w^hich effect fermentation and
putrefaction, and in the regularity with which the
distribution of the elements takes place in the sub-
sequent transformations. This regularity depends
exclusively on the unequal affinity which they possess
for each other in an isolated condition. The action
of water on wood, charcoal, and cyanogen, the sim-
plest of the compounds of nitrogen, suffices to illus-
trate the whole of the transformations of organic
bodies ; of those in which nitrogen is a constituent,
and of those in which it is absent.

CHAPTER IV.

ON THE TRANSFORMATION OF BODIES WHICH DO NOT CON-
TAIN NITROGEN AS A CONSTITUENT, AND OF THOSE IN
WHICH, IT IS PRESENT.

When oxygen and hydrogen combined in equal
equivalents, as in steam, are conducted over char-
coal, heated to the temperature at which it possesses
the power to enter into combination with one of
these elements, a decomposition of the steam ensues.
An oxide of carbon (either carbonic oxide or car-
bonic 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. Accordingly, 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.
26^

306 CHEMICAL TRANSFORMATIONS

Acetic and meconic* acids suffer a true transform-
ation under the influence of heat, that is, their com-
ponent elements are disunited, and form new com-
pounds without any of them being singly disen-
gaged. Acetic acid is converted into acetone and
carbonic acid (C4 H3 03= C3 H3 0 + C02), and
meconic acid into carbonic acid and komenic acid ;
whilst by the influence of a higher temperature, the
latter is further decomposed into pyromeconic acid
and carbonic acid.

' Now in these cases the carbon of the bodies de-
composed is shared between the oxygen and hydro-
gen ; part of it unites with the oxygen and forms
carbonic acid, whilst the other portion enters into
combination with the hydrogen, and an oxide of a
carbo-hydrogen 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 carbo-hydro-
gen which contains 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 compounds must result merely from the
elements arranging themselves, according to the
degree of their mutual affinities, into new combina-
tions, which are constant and unchangeable in the
conditions under which they were originally formed,
but undergo changes when these conditions become
different. If we compare the products of two bod-
ies, similar in composition but different in properties,
which are subjected to transformations by two differ-
ent 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

* An acid existing in opium, and named from the Greek for poppy.

OF BODIES CONTAINING NITROGEN. 307

between the oxygen and hydrogen of its own sub-
stance, 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
§ 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 other words, that the
products differ ad infinitum^ according to the com-
position of the original substance.

ON THE 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 com-
pounds, a transposition of their elements occurs
spontaneously as soon as they cease to form a part
of a living organism ; that is, when they are drawn

* C carbon, H hydrogen, O oxygen.

308 CHEMICAL TRANSFORMATIONS

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 combination, but which are unknown in an
isolated condition, because their elements, freed from
the power by which they were held together, arrange
themselves according to their own natural attrac-
tions. Hypermanganic, manganic, and hyposulphu-
rous acids, belong to this class of substances, which
however are rare.

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 partic-
ular 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 sep-
aration from the matters with which it is united.

It is only when the quantity of nitrogen exceeds
a certain limit, that azotized compounds have some
degree of permanence, as is the case with melamin,
ammelin, &c. Their liability to change is also dimin-
ished, when the quantity of nitrogen is very small
in proportion 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 fulmin-
ating compounds.

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

OF BODIES CONTAINING NITROGEN. 309

are found in animal bodies, do not enter into a state
of putrefaction when dry.

The result of the known transformations of azo-
tized 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 in-
variably 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 on by alkalies. Acids, and increase of tempera-
ture, produce the same effect. It is only when there is
a deficiency of water or its elements, that cyanogen
or other azotized compounds are produced.

From these facts it may be concluded, that am-
monia is the most stable compound of nitrogen ; and
that hydrogen and nitrogen possess a degree of
affinity for each other surpassing the attraction of
the latter body for any other element.

Already, in considering the transformations of sub-
stances destitute of nitrogen, we have recognised
the great affinity of carbon for oxygen as a power-
ful cause for effecting the disunion of the elements
of a complex organic atom in a definite manner. But
carbon is also invariably contained in azotized or-
ganic compounds, 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 element, and in those in which
that substance is present, two elements, which mutu-
ally share the elements of water. Hence there are
two opposite affinities at play, which mutually
strengthen each other's action.

Now we know, that the most pow^erful attractions
may be overcome by the influence of two affinities.

310 CHEMICAL TRANSFORMATIONS

Thus, a decomposition of alumina may be effected
with the greatest facility, when the affinity of char-
coal for oxygen, and of chlorine for aluminium, 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 component parts, and a strong
disposition to yield to transformations, 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
perhaps the best adapted to convey a distinct idea
of the manner in which the atoms are disposed of in
transformations. This acid contains nitrogen, hy-
drogen, and oxygen, in such proportions, that the
addition of a certain quantity of the elements of
water is exactly sufficient to cause the oxygen con-
tained in the water and acid to unite with the car-
bon and form carbonic acid, and the hydrogen of the
water to combine with the nitrogen and form am-
monia. The most favorable conditions for a com-
plete transformation are, therefore, associated in
these bodies, and it is well known, that the disunion
takes place on the instant in which 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,
because 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.

OF BODIES CONTAINING NITROGEN. 311

The transformations of cyanogen, a body com-
posed of carbon and nitrogen, and the simplest of all
the compounds 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 putre-
faction 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 brownish
black matter, which is a combination of ammonia
with another body, produced by the simple union of
cyanogen with water. This substance is insoluble
in water, and is thus enabled to resist further change.

A second transformation is effected by the cyano-
gen being shared between the elements of the water,
in consequence of which cyanic acid is formed by a
certain quantity of the cyanogen combining w^th the
oxygen of the water, while hydrocyanic acid is also
formed by another portion of the cyanogen uniting
with the hydrogen 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
mentioned above, cannot exist in contact with water,
being decomposed immediately into carbonic acid
and ammonia. The cyanic acid, however, newly
formed in the decomposition of cyanogen, escapes
this decomposition by entering into combination w^ith
the free ammonia, by which urea * is produced.

The hydrocyanic acid is also decomposed into a
brown matter which contains hydrogen and cyano-
gen, the latter in greater proportion than it does in
the gaseous state. Oxalic acid, urea, and carbonic
acid, are also formed by its decomposition, and /orm-

* See page 87, note.

312 CHEMICAL TRANSFORMATIONS.

ic acid and ammonia are produced by the decompo-
sition 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 are formed by the transformation of the
original body, its elements being shared between the
constituents of water ; others are produced in con-
sequence 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 as-
sisted.

These examples show, that the results of decompo-
sition by fermentation or putrefaction comprehend
very different phenomena. The first kind of trans-
formation is, the transposition of the elements of one
complex compound, by which new compounds are
produced with or without the assistance of the ele-
ments of water. In the products newly formed in
this manner, either the same proportions of those
component parts which were contained in the mat-
ter 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 com-
plex 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 transformation, the new products
contain the sum of the constituents of all the com-
pounds which had taken a part in the decomposition.

The first of these two modes of decomposition is
that designated fermentation^ the second putrefac-
tion ; and when these terms are used in the following
pages, it will always be to distinguish the two pro-
cesses above described, which are so different in
their results.

FERMENTATION OF SUGAR. 313

CHAPTER V.

FERMENTATION OF SUGAR.

The peculiar decomposition, which sugar suffers,
may be viewed as a type of all tKe transformations
designated fermentation.'*

Thenard obtained from 100 grammes f of cane-
sugar 0-5262 of absolute alcohol. 100 parts of sugar
from the cane yield, therefore, 103-89 parts of car-
bonic acid and alcohol. 'The entire carbon in these
products is equal to 42 parts, which is exactly the
quantity originally contained in the sugar.

The analysis of sugar from the cane, proves that
it contains the elements of carbonic acid and alco-
hol, minus 1 atom of water. The alcohol and car-
bonic acid produced by the fermentation of a certain
quantity of sugar, contained together one equivalent
of oxygen, and one equivalent of hydrogen, the ele-
ments, therefore, of one equivalent of water, more
than the sugar contained. The excess of weight in
the products is thus explained most satisfactorily ;
it is owing, namely, to the elements of water having
taken part in the metamorphosis of the sugar.

It is known, that 1 atom of sugar contains 12
equivalents of carbon, both from the proportions in
which it unites with bases, and from the composition

* When yeast is made into a thin paste with water, and 1 cubic centi-
metre of this mixture introduced into a graduated glass receiver filled
with mercury, in which are already 19 grammes of a solution of cane-
sugar, containing I 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 076
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 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 0503 to 0*5127 grammes by
weight. — L.

t The gramme equals 15-4440 grains.

314 FERMENTATION OF SUGAR.

of saccharic acid, the product of its oxidation. Now
none of these atoms of carbon are contained in the
sugar as carbonic acid, because the whole quantity is
obtained as oxalic acid, when sugar is treated with
hypermanganate 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 high-
er, 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 converted into water and a kind of carbona-
ceous matter, when treated with acids, particularly
with such as contain 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 this metamorphosis of sugar, the elements of
the yeast, by contact with which its fermentation
was effected, take no appreciable part in the trans-
position 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 vegeta-
ble 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 common temperatures, it fer-
ments like a solution of sugar. Carbonic acid gas
escapes from it with effervescence, 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 decomposi-
tion at a temperature of from 95^ to 104° (350 — 40^
C). Gases possessing an offensive smell are evolved

YEAST OR FERMENT. 315

in considerable quantity, and when the liquor is ex-
amined after the decomposition is completed, no al-
cohol can be detected. The sugar has also disap-
peared, and with it all the azotized compounds which
existed in the juice previously to its fermentation.
Both were decomposed at the same time ; the nitro-
gen 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 organism ;
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 calculating 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 detected in the juice before fer-
mentation. They must, therefore, have been formed
by the interchange of the elements of the sugar with
those of the foreign substances also present. It is
this mixed transformation of two or more compounds
which receives the special name of putrefaction.

YEAST OR FERMENT.

When attention is directed to the condition of
those substances, which possess the power of induc-
ing fermentation and putrefaction in other bodies,
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
transposition.

The characters of the remarkable matter, which is
deposited in an insoluble state during the fermenta-
tion of beer, wine, and vegetable juices, may first be
studied.

316 . YEAST OR FERMENT.

This substance, which has been called yeast ov fer-
ment, from the power which it possesses of causing
fermentation in sugar, or saccharine vegetable juices,
possesses all the characters of a compound of nitro-
gen in the state of ^putrefaction and eremacausis.

Like wood in the state of eremacausis, yeast con-
verts the oxygeji of the surrounding air into carbon-
ic acid, but it also evolves this gas from its own
mass, like bodies in the state of putrefaction. (Colin.)
When kept under water, it emits carbonic acid, ac-
companied by gases of an offensive smell, (Thenard,)
and is at last converted 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 bodies. The presence of wa-
ter is quite necessary for sustaining the properties
of ferment, for by simple pressure its power to ex-
cite fermentation is much diminished, and is com-
pletely destroyed by drying. Its action is arrested
also by the temperature of boiling water, by alcohol,
common salt, an excess of sugar, oxide of mercury,
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 residue does not produce fermentation.

The soluble part of ferment likewise does not excite
fermentation. An aqueous infusion of yeast may be
mixed with a solution of sugar, and preserved in
vessels from which the air is excluded, w^ithout eith-
er experiencing 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 power ? 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 infu-

ITS PROPERTIES. 317

sion must be allowed to cool in contact with the air,
and to remain some time exposed to its action. 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 property.

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
action 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 com-
pleted, part of the yeast itself has disappeared.

From 20 parts of fresh yeast from beer, and 100
parts of sugar, Thmard obtained, after the fermen-
tation was completed, 13*7 parts of an insoluble
residue, which diminished to 10 parts when employed
in the same way with a fresh portion of sugar.
These ten parts were white, possessed of the prop-
erties of woody fibre, and had no further action on
sugar.

It is evident, therefore, that during the fermenta-
tion of sugar by yeast, both of these substances
suffer decomposition at the same time, and disappear
in consequence. But if yeast be a body which ex-
cites fermentation by being itself in a state of de-
composition, all other matters in the same condition
should have a similar action upon sugar ; and this is
in reality the case. Muscle, urine, isinglass, osma-
zome,* albumen, cheese, gliadine, gluten, legumin,
and blood, when in a state of putrefaction, have all
the power of producing the putrefaction, or fermen-
tation of a solution of sugar. Yeast, w^hich by con-
tinued washing has entirely lost the property of in-
ducing fermentation, regains it when its putrefaction

* 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.

27*

318 YEAST OF FERMENT.

has recommenced, in consequence of its being kept in
a warm situation for some time.

Yeast and putrefying animal and vegetable mat-
ters act as peroxide of hydrogen does on oxide of
silver, when they induce bodies with which they are
in contact to enter into the same state of decompo-
sition. The disturbance in the attraction of the con-
stituents of the peroxide of hydrogen effects a dis-
turbance in the attraction of the elements of the
oxide of silver, the one being decomposed, on ac-
count of the decomposition of the other.

Now if we consider the process of the fermentation
of pure sugar, in a practical 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 transformation of all the sugar is effected. Some
sugar here remains undecomposed, because the cause
of its transformation is absent, viz. contact with a
body in a state of decomposition.

But when the quantity of ferment predominates, a
certain quantity of it remains after all the sugar has
fermented, its decomposition proceeding very slowly,
on account of its insolubility in water. This residue
of ferment is still able to induce fermentation, when
introduced 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 in 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 ex-
istence of a new cause, which effects combinations
and decompositions. This cause is the action which
bodies in a state of combination or decomposition
exercise upon substances, the component parts of
which are united together by a feeble affinity. This

AZOTIZED MATTERS THE CAUSE OF PUTREFACTION. 319

action resembles a peculiar power, attached to a
body in the state of combination or decomposition,
but exerting its influence beyond the sphere of its
own attractions. We are now able to account satis-
factorily for many known phenomena.

A large quantity of hippuric acid may be obtained
from the fresh urine of a horse, by the addition of
muriatic acid; but when the urine has undergone
putrefaction, 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 urea is added to a solution of
sugar in the state of fermentation, it is decomposed
into carbonic acid and ammonia. No asparagin*
can be detected in a putrefied infusion of asparagin,
liquorice-root, or the root of marshmallow (^Althcea
officinalis).

It has already been mentioned, that the strong
affinity of nitrogen for hydrogen, and that of carbon
for oxygen, are 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 different elements of the compounds
strive to take possession of the different elements
of water. Now since it is found that no body desti-
tute of nitrogen, possesses, when pure, the property
of decomposing spontaneously whilst in contact with
water, we must ascribe this property which azotized
bodies possess in so eminent a degree, to something
peculiar in the nature of the compounds of nitrogen,
and to their constituting, in a certain measure, more
highly organized atoms.

Every azotized constituent of the animal or vege-
table organism runs spontaneously into putrefaction,
when exposed to moisture and a high temperature.

Azotized matters are, accordingly, the only causes
of fermentation and putrefaction in vegetable sub-
stances.

* A peculiar principle obtained from asparagus. See Brande's
Chemistry f p. 1042.

320 YEAST OR FERMENT.

Putrefaction, on account of its effects, as a mixed
transformation of many different substances, may be
classed with the most powerful processes of deoxi-
dation, by which the strongest affinities are over-
come.

When a solution of gypsum in water is mixed with
a decoction of sawdust, or any other organic matter
capable 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 car-
bonic and free hydrosulphuric acid, between which
the lime of the gypsum is shared. In stagnant water
containing sulphates in solution, cry&tallized pyrites
is observed to form on the decaying roots.

Now we know, that in the putrefaction of wood
under water, when air therefore is excluded, a part
of its carbon 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 de-
composed water are liberated either in a pure state,
or as carburetted hydrogen. The products of this
decomposition are of the same kind as those genera-
ted when steam is conducted over red-hot charcoal.

It is evident, that if with the water a substance
containing a large quantity of oxygen, such as sul-
phuric 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 decomposition will be water
and metallic sulphurets.

The putrefied leaves of woad (^Isatis tinctoria), in
contact with indigo-blue, water, and alkalies, suffer
further decomposition, and the indigo is deoxidized
and dissolved.

The mannite formed by the putrefaction of beet-
roots and other plants which contain sugar, contains

DIFFERENCE OF FERMENTATION AND PUTREFACTION. 321

the same number of equivalents of carbon and hydro-
gen as the sugar of grapes, but two atoms less of
oxygen ; and it is highly probable that it is produced
from sugar of grapes, contained in those plants, in
precisely the same manner as indigo-blue is con-
verted into deoxidized white indigo.

During the putrefaction of gluten, carbonic acid
and pure hydrogen gas are evolved ; phosphate,
acetate, caseate, and lactate of ammonia being at
the same time produced in such quantity, that the
further decomposition of the gluten ceases. But
when the supply of water is renewed, the decompo-
sition begins again, and in addition to the salts just
mentioned, carbonate of ammonia and a white crys-
talline matter resembling mica (caseous oxide) are
formed, together with hydrosulphate of ammonia,
and a mucilaginous substance coagulable by chlorine.
Lactic acid is almost always produced by the putre-
faction of organic bodies.

We may now compare fermentation and putrefac-
tion with the decomposition which organic com-
pounds suffer under the influence of a high tempera-
ture. Dry distillation 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 pro-
portion of hydrogen are necessarily produced. Fer-
mentation may be considered as a process of com-
bustion or oxidation of a similar kind, taking place
in a liquid between the elements of the same mattery
at a very slightly elevated temperature ; and putre-
faction as a process of oxidation, in which the oxy-
gen of all the substances present comes into play.

322 EREMACAUSIS OR DECAY.

CHAPTER VI.

EREMACAUSIS, OR DECAY.

In organic nature, besides the processes of decom-
position named fermentation and putrefaction, an-
other 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 com-
bustible elements of a body with the oxygen of the
air ; a slow combustion or oxidation, to which we
shall apply the term of eremacmisis.

The conversion of wood into humus, the formation
of acetic acid out of alcohol, nitrification, and numer-
ous 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
absorption of oxygen, and, consequently, their ere-
macausis. The property of suffering this change is
possessed in the highest degree by substances con-
taining nitrogen.

When vegetable juices are evaporated by a gentle
heat in the air, a brown or brownish-black substance
is precipitated as a product of the action of oxygen
upon them. This substance, which appears to pos-
sess similar properties from whatever juice it is
obtained, has received the name of extractive matter;
it is insoluble or very sparingly soluble in water, but
is dissolved with facility by alkalies. By the action
of air on solid animal or vegetable matters, a similar

EREMACAUSIS OR DECAY. 323

:)ulverulent brown substance is formed, and is known
jj the name of humus.

The conditions which determine the commence-
ment of eremacausis are of various kinds. Many-
organic substances, particularly such as are mixtures
3f several more simple matters, oxidize in the air
when simply moistened with water; others not until
;they are subjected to the action of alkalies; 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, hsematin,* and many
other compounds, may be dissolved in water and yet
remain unaltered ; 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. They now contain an azotized sub-
stance, not in the form of ammonia.

All these facts show, that the action of oxygen
seldom affects the carbon of decaying substances,

* The coloring matter of logwood.

324 EREMACAUSIS OR DECAY,

and this corresponds exactly to what happens in
combustion at high temperatures. It is well known,
for example, that when no more oxygen is admitted
to a compound of carbon and hydrogen than is suffi-
cient to combine with its hydrogen, the carbon is not
burned, but is separated as lampblack;* while, if
the quantity of oxygen is not sufficient even to con-
sume all the hydrogen, new compounds* are formed,
such as napthalinf and similar matters, which con-
tain a smaller proportion of hydrogen than those
compounds of carbon and hydrogen which previously
existed in the combustible substance.

There is no example of carbon combining directly
with oxygen at common temperatures, but numerous
facts show that hydrogen, in certain states of con-
densation, possesses that property. Lampblack which
has been heated to redness may be kept in contact
with oxygen gas, without forming carbonic acid;
but lampblack, 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 surrounding
it ; it is not formed until the temperature of the mass
has reached a red heat. The heat which produces
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 compre-
hends those substances which unite with the oxygen
of the air, 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

* As in the combustion of spirits of turpentine, now much employed,
under various names, in lamps.

t A substance obtained from coal tar.

EXAMPLES OF. 325

iair, it absorbs two equivalents of oxygen, and is con-
verted into benzoic acid; but half of the oxygen ab-
sorbed combines with the hydrogen of the oil, and
forms water, which remains in union with the anhy-
drous benzoic acid.*

But, although it appears very probable that the
oxygen acts primarily and principally upon hydro-
gen, 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 oxygen, when every particle of
it is surrounded with hydrogen, an element with
which the oxygen combines with greater facility.

We know, on the contrary, that although nitrogen
cannot be made to combine with oxygen directly, yet
it is oxidized and forms nitric acid, when mixed
with a large 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 communicated to it. It is conceivable,
that in a similar manner, the carbon may be directly
oxidized in several cases, obtaining from its con-
tact with hydrogen in eremacausis a property which
it does not itself possess at common temperatures.
But the formation of carbonic acid during the ere-
macausis of bodies containing hydrogen, must in
most cases be ascribed to another cause. It appears

* According to the experiments of Dobereiner, 100 parts of pyrogal-
lic acid absorb 38*09 parts of oxygen when in contact with ammonia
and water ; the acid being changed in consequence of this absorption
into a mouldy substance, which contains less oxygen than the acid it-
self. 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 ab-
sorbed with that of the hydrogen contained in the acid, that they are
exactly in the proportions for forming water.

W^hen colorless orcin is exposed together with ammonia to the con-
tact of oxygen gas, the beautiful red-colored orcein is produced. Now;,,
the only changes which take place here are, that the absorption of oxy-
gen by the elements of orcin and ammonia causes the formation of
water ; 1 equivalent of orcin C18 H12 08, and 1 equivalent of ammo-
nia NH3, absorb 5 equivalents of oxygen, and 5 equivalents of water
are produced, the composition of orcein being C18 HIO 08 N. (Du-
mas ) In this case it is evident, that the oxygen absorbed has united
merely with the hydrogen. — L.

326 EREMACAUSIS OR DECAY.

to be formed in a manner similar to the formation of
acetic acid, by the eremacausis of saliculite of pot-
ash.^

An alkaline solution of hsematin being exposed to
an atmosphere of oxygen, 0*2 grm. absorb 28*6 cubic
centimeters of oxygen gas in twenty-four hours, the
alkali acquiring at the same time 6 cubic centimeters
of carbonic acid. (Chevreul.) But these 6 cubic
centimeters of carbonic acid contain only an equal
volume of oxygen, so that it is certain from this ex-
periment, that I 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 hsematin, and had separated from the other ele-
ments as carbonic acid.

The experiments of De Saussure upon the decay
of woody fibre show, that such a separation is quite
possible. Moist woody fibre evolved one volume of
carbonic acid for every volume of oxygen w^hich it
absorbed. It has just been mentioned, that carbonic
acid contains its 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 car-
bon cannot be considered as at all probable, without
rejecting all the facts established by experiment re-
garding the process of combustion at low tempera-
tures.

* This salt, when exposed to a moist atmosphere, ahsorbs 3 atoms of
oxygen; melanic acid is produced, a body resembling humus, in conse-
quence of the formation of which, the elements of 1 atom of acetic acid
are separated from the saliculous acid. — L.

FORMATION OF CARBONIC ACID. 327

If we examine the action of oxygen upon a sub-
stance containing a large quantity of hydrogen,, such
as alcohol, we find most distinctly, that the direct
iiformation of carbonic acid is the last stage of its
j oxidation, and that it is preceded by a series of
! changes, the last of which is a complete combustion
of the hydrogen. Aldehyde, acetic, formic, oxalic,
and carbonic acids, form a connected chain of pro-
ducts arising from the oxidation of alcohol ; and the
successive changes which this fluid experiences from
the action of oxygen may be readily traced in them.
Aldehyde is alcohol minus hydrogen ; acetic acid is
formed by the direct union of aldehyde 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 pro-
duced ; and the latter acid is converted into car-
bonic acid by uniting with an additional portion of
oxygen. 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 product, the carbonic acid, does
not take place until all the hydrogen has been ab-
stracted.

The absorption of oxygen by drying oils certainly
does not depend upon the oxidation of their carbon;
for in raw nut-oil, for example, which was not free
from mucilage and other substances, only twenty-one
volumes of carbonic acid were formed for every 146
volumes of oxygen gas absorbed.

It must be remembered, that combustion or oxida-
tion at low temperatures produces results quite simi-
lar 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 combus-
tibility is caused by its being enabled to unite with
oxygen at a temperature at which the other elements
cannot enter into that combination ; this property
having the same effect as a greater affinity.

328 EREMACAUSIS OR DECAY

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 combination 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 affini-
ty for oxygen than either of those substances.

In putrefaction, the conditions are evidently pres-
ent, under which the affinity of carbon for oxygen
comes into play; neither expansion, cohesion, nor
the gaseous state, opposes it, whilst in eremacausis
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 transposition of the elements or disturbance in
their attractions, similar to that which gives rise to
the formation of carbonic acid in the processes of
fermentation and putrefaction.

The eremacausis of such substances is, therefore,
a decomposition analogous to the putrefaction of
azotized bodies. For in these there are two affini-
ties at play; the affinity of nitrogen for hydrogen,
and that of carbon for oxygen, and both facilitate the
disunion of the elements. Now there are two affini-
ties also in action in those bodies which decay with
the evolution of carbonic acid. One of these affini^
ties is the attraction of the oxygen of the air for the

OF BODIES DESTITUTE OF NITROGEN. 329

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 circum-
.stances.

When wood putrefies in marshes, carbon and oxy-
gen are separated from its elements in the form of
carbonic acid, and hydrogen in the form of carburet-
ted hydrogen. But when wood decays or putrefies
in the air, its hydrogen does not combine with car-
bon, but with oxygen, for which it has a much great-
er affinity at common temperatures.

Now it is evident, from the complete similarity of
these processes, that decaying and putrefying bodies
can mutually 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 mat-
ters into that of putrefaction when air is excluded.
All bodies, likewise, in a state of decay are capable
of inducing putrefaction in other bodies in the same
manner as putrefying bodies themselves do.

CHAPTER VII.

EREMACAUSIS OR DECAY OF BODIES DESTITUTE OF
NITROGEN: FORMATION OF ACETIC ACID.

All those substances which appear to possess the
property of entering spontaneously into fermenta-
tion and putrefaction, do not in reality suffer those
changes without 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 transformation in the in-
terior of the substances show themselves.

28*

330 EREMACAUSIS OR DECAY

It is a very general error to suppose that organic
substances have the power of undergoing change
spontaneously, without the aid of an exteimal cause.
When they are not in a state of change, it is neces-
sary, before they can assume that state, that the ex-
isting equilibrium of their elements should be dis-
turbed ; and the most common cause of this distur-
bance is undoubtedly the atmosphere which surrounds
all bodies.

The juices of the fruit or other part of a plant
which very readily undergo decomposition, retain
their properties unchanged as long as they are pro-
tected from immediate contact with the air, that is,
as long as the cells or organs in which they are con-
tained resist the influence of the air. It is not until
after the 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 important practical improvements to which they
have led, are the best proofs that the atmosphere
possesses an influence upon the changes of organic
substances. The juice of grapes which were ex-
pressed under a receiver filled with mercury, so that
air was completely excluded, did not ferment. But
when the smallest portion of air was introduced, a
certain quantity of oxygen became absorbed, and
fermentation immediately began. Although the juice
was expressed from the grapes in contact with air,
under the conditions therefore necessary to cause its
fermentation, still this change did not ensue when
the juice was heated in close vessels to the tempera-
ture 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

OF BODIES DESTITUTE OF NITROGEN. 331

heated 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-flavoured as when origi-
nally placed in them.*

The action of the oxygen in these processes of
decomposition is very simple ; it excites changes in
the composition of the azotized matters dissolved in
the juices, — the mode of combination of the elements
of those matters undergoes a disturbance and change
in consequence of their contact with oxygen. The
oxygen acts here in a similar manner to the friction
or motion which affects the mutual decomposition of
two salts, the crystallization of salts from their
solution, or the explosion 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
excited, the presence of oxygen is no longer neces-
sary. 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 propagated through the substance.
The air may now be completely excluded, but the

* 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
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 allowed to
cool, and from the diminution of volume, in consequence of the re-
duction of temperature, both ends of the cylinder are pressed inwards
and become concave. The tin cases, thus hermetically sealed, are ex-
posed in a test-chamber, for at least a month, to a temperature above
what they are ever likely to encounter; from 90° to 110° F. If the
process has failed, putrefaction takes place, and gas 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 detected in the proving process.
— Ure's Diet, of Arts and Manuf.

332 EREMACAUSIS OR DECAY

fermentation or putrefaction proceeds uninterrupted-
ly to its completion. It has been remarked, that the
mere contact of carbonic acid is sufficient to produce
fermentation in the juices of several fruits.

The contact of ammonia and alkalies in general
may be mentioned amongst the chemical conditions,
which determine the commencement of eremacausis ;
for their presence causes many substances to absorb
oxygen and to decay, in which neither oxygen nor
alkalies alone produce that change.

Thus alcohol does not combine with the oxygen
of the air at common temperatures. But a solution
of potash in alcohol absorbs oxygen with much
rapidity, and acquires a brown color. The alcohol is
found after a short time to contain acetic acid, form-
ic 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
eremacausis 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 communication 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 moistened gall-nuts converts the tannic acid with
such rapidity into gallic acid.

A most remarkable and decided example of this
induction 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 fermentation or putrefaction, converts oxygen
gas which may surround it into carbonic acid, with-
out change of volume. Now, De Saussure added
a certain quantity of hydrogen gas to the oxygen,
and observed a diminution in volume immediately
after the addition. A part of the hydrogen gas had
disappeared, and along with it a portion of the oxy-

OF BODIES DESTITUTE OF NITROGEN. 333

gen, but a corresponding quantity of carbonic acid
gas had not been formed. The hydrogen and oxy-
gen 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 in-
duced by mere contact with matter in the state of
eremacausis. The action of the decaying substance
here produced results exactly similar to those effect-
ed by spongy platinum ; but that they proceeded
from a different cause was shown by the fact that
the presence of carbonic oxide, w^hich arrests com-
pletely the action of platinum on carburetted hydro-
gen, did not retard in the slightest degree the com-
bustion 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 antiseptic 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 principle is in reality at-
tended to in the manufactories in which acetic acid
is prepared according to the new plan. In the pro-
cess there adopted all the conditions are afforded
for the eremacausis of alcohol, and for its consequent
conversion into acetic acid.

The alcohol is exposed to a moderate heat, and
spread over a very extended surface, but these con-
ditions 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 eremacausis by mere contact
with oxygen, or by its fermentation or putrefaction

334 EREMACAUSIS OR DECAY

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 contain 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 decomposition or
eremacausis, which impresses the same condition
upon the atoms of alcohol in its vicinity ; exactly as
in the case of an alloy of platinum and silver dis-
solving in nitric acid, in which the platinum becomes
oxidized, by virtue of an inductive action exercised
upon it by the silver in the act of its oxidation.
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 affin-
ity for oxygen as sulphurous acid, and combines,
therefore, directly with it, producing acetic acid.

CHAPTER VIIL

EREMACAUSIS OF SUBSTANCES CONTAINING NITROGEN.

NITRIFICATION.

When azotized substances are burned at high
temperatures, their nitrogen does not enter into
direct combination with oxygen. The knowledge
of this fact is of assistance in considering the pro-
cess 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

OF BODIES CONTAINING NITROGEN. 335

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 proportion of hydrogen and car-
bon ; a separation of the carbon of the latter sub-
stances in an uncombined state takes place, and in
the same way the substances containing 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 ;
nitric acid is never formed.

But when alkalies or alkaline bases are present, a
union of oxygen with the nitrogen takes 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 decom-
position which proceed in nature, still we find that
the final result depends on a succession of actions,
which are essentially influenced by the chemical
nature of the bodies submitted to decomposition.

When it is observed that the character of a sub-
stance remains unaltered in a whole series of phe-
nomena, there is no reason to ascribe a new charac-
ter 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 state of combustion or oxidation, that nitro-
gen 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 nitro-

336 EREMACAUSIS OR DECAY

gen is very rarely produced, and never when the
carbon is in excess. Kuhlmann found in his experi-
ments, that it was only when cyanogen was mixed
with an excess of oxygen gas, and conducted over
spongy platinum, that nitric acid was generated.

Kuhlmann could not succeed in causing pure nitro-
gen to combine directly with oxygen, even under
the most favorable circumstances; thus, with 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 (a com-
pound of hydrogen and nitrogen) cannot be exposed
to the action of oxygen^ without the formation of an
oxide of nitrogen, and in con&equence the production
of nitric acid. ^

It is owing to the great facility with which ammo-
nia is converted into nitric acid, that it is so difficult
to obtain 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 com-
pletely or partially, into binoxide 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 w^hen 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 com-
bustion 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

OF BODIES CONTAINING NITROGEN. 337

exhibits such a strong disposition to become con-
verted into nitric acid is, undoubtedly, that the two
products, which are the result of the oxidation of
the constituents of ammonia, possess the power of
uniting with one another. Now this is not the case
in the combustion of compounds of carbon and
nitrogen; here one of the products 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 superior
affinity of its carbon for the oxygen during the act
of its formation will aid 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 essential to
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 possesses 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 general cause of
nitrification on the surface of the earth.

Azotized animal matter is not, therefore, the im-
mediate cause of nitrification ; it contributes to the
production 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
substances which themselves contained no azotized
matter. It is known, also, that porous substances
possess generally the power of condensing ammonia;,

338 VINOUS FERMENTATION.

there are few ferruginous earths which do not evolve
ammoniacal products when heated to redness, and
ammonia is the cause of the peculiar smell perceived
upon moistening aluminous minerals. Thus, ammo-
nia, by being a constituent of the atmosphere, is a
very widely diffused cause of nitrification, which
will come into play whenever the different conditions
necessary for the oxidation of ammonia are com-
bined. 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 generated 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 fermenta-
tion 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 de-
composition of the sugar contained in the fluid. But
it was also stated, that the process once commenced,
continues until all the sugar is completely decom-
posed, quite independently 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 pro-
duced a yellow or gray insoluble substance, contain-
ing a large quantity of nitrogen. It is this body
which possesses the power of inducing fermentation

YEAST FEOM BEER AND WTNE. 339

in a new solution of sugar, and which has in conse-
quence received the name of 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 which consisted | of
carbonic acid, and \ of pure hydrogen gas ; ammo-
niacal salts of several organic acids were formed at
the same time. Water must, therefore, be decom-
posed during the putrefaction 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 formed in this case ;
and we have seen that in the fermentation of sac-
charine vegetable juices, no escape of hydrogen gas
takes place.

It is evident, that the decomposition which gluten
suffers in an isolated state, and that which it under-
goes when dissolved in a vegetable juice, belong to
two different 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 cer-
tain 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 gen-
eral, become turbid when in contact with air, before
fermentation commences; and this turbidness is owing
to the formation of an insoluble precipitate of the
same nature as ferment.

From the phenomena which have been observed
during the fermentation of wort,* it is known with

* Wort is an infusion of malt ; it consists of the soluble parts of this
substance dissolved in water. — Ed.

340 VINOUS FERMENTATION.

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 mat-
ter of the corn, namely, gluten in the same condition
as it exists in the juice of grapes. The wort fer-
ments by the addition of yeast, but after its decom-
position 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 un-
der the microscope, present the same form and gen-
eral 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 pu-
trefaction 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 in-
soluble state. These considerations, therefore, as well
as the circumstance which all the experiments made
on this subject appear to point out, that the conver-
sion of gluten to the insoluble state is the result of
oxidation, lead us to conclude, that the oxygen con-
sumed in this process is derived from the elements
of water, or from the sugar which contains oxygen
and hydrogen in the same proportion- as water. At
all events, the oxygen thus consumed in the fermen-
tation of wine and beer is not taken from the at-
mosphere.

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 sugar; but in the latter, a
transformation of gluten is effected at the same time,

■* The liquid expressed from grapes when fully ripe is called must.

OILY AND ETHEREAL PRODUCTS. 341

by which ferment is generated. Thus yeast is de-
stroyed 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 evi-
dent 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 combinations, or by the deoxidation
of the sugar, new compounds containing a large pro-
portion 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
substances which could not be detected before their
fermentation, and which must have been formed,
therefore, during that process in a manner similar to
the production of mannite. The smell and taste
"which distinguish wine from all other fermented
liquids are known to depend upon an ether of a vol-
atile and highly combustible acid ; the ether is of an
oily nature, and has received the name (Enanthic
ether. It is also ascertained, that the smell and
taste of brandy from corn and potato are owing to a
peculiar oil, the oil of potatoes. This oil is more
closely allied to alcohol in its properties, 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 remarkable for the large quantity of hydrogen
which enters into their composition.

(Enanthic acid contains an equal number of equiv-
alents of carbon and hydrogen, exactly the same
proportions 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

29*

344 VINOUS FERMENTATION.

various modifications in the nature of the products
generated.

Whatever opinion, however, may be held regard-
ing the origin of the volatile odoriferous substances
obtained in the fermentation of wine, it is quite cer-
tain that the characteristic smell of wine is owing
to an ether of an organic acid, resembling one of the
fatty acids (oenanthic ether).

It is only in liquids which contain other very solu-
ble acids, that the fatty acids and cenanthic acids 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 ox-
ides in general, and combines with the alkalies.

The principal constituent of this oil is an acid
identical 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 hy-
drate of an organic base analogous to ether, and
capable, therefore, of entering into combination with
acids. It is formed in considerable quantity in fer-
menting liquids which are slightly alkaline; under
circumstances, consequently, in which it is incapable
of combining with an acid.

The products of the fermentation and putrefaction
of neutral vegetable and animal matters are gener-
ally accompanied by substances of an oflfensive odor;
but the most remarkable example of the generation
of a true ethereal oil is seen in the fermentation of

ODORIFEROUS PRODUCTS. 345

the Herha centaurium minorius, a plant which pos-
sesses no smell. When it is exposed in water to a
slightly elevated temperature it ferments, and emits
an agreeable penetrating odor. By the distillation
of the liquid, an ethereal oily substance of great vola-
tility is obtained, which excites a pricking sensation
in the eyes, and a flow of tears. (Biichner.)

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 fatty crystallizable substance swims,
w^hich does not contain nitrogen, and is quite desti-
tute of smell. But w^hen 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 com-
mences, and is accompanied by the absorption of
oxygen ; the leaves now become w^arm and emit the
characteristic smell of prepared tobacco and snufF.
When the fermentation is carefully promoted and
too high a heat avoided, this smell increases and be-
comes more delicate; and after the fermentation is
completed, an oily azotized volatile matter called
nicotine is found in the leaves. This substance,
— 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 diff*erent odori-
ferous substances, which are generated along with
the nicotine.

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, that others emit a smell only when they
undergo change or decomposition.

Arsenic and arsenious acid are both quite inodor-
ous. 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 turpen-.

346 VINOUS FERMENTATION.

tine, 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 prin-
ciple 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 communicate a very strong taste and
smell, which the addition of the water distilled from
a quantity a hundred times greater would not effect.
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 fictitious perfume
thus obtained differs from the genuine aroma, by its
inferior durability, and by being gradually dissi-
pated.

The juice of grapes grown in different climates
differs not only in the proportion of free acid which
it contains, but also in respect to the quantity of
sugar dissolved in it. The quantity of azotized
matter in the juice seems to be the same in whatever
parts the grapes may grow ; at least no difference
has been observed in the amount of yeast formed
during fermentation in the south of France, and on
the Rhine.

The grapes grown in hot climates, 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

VAEIOUS PROPERTIES OF WINES. ^ 347

into alcohol and carbonic acid. A certain quantity
of the sugar consequently remains mixed with the
wine in an undecomposed state, the condition neces-
sary for its further decomposition 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
transformation 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 becom-
ing spontaneously converted into vinegar, when the
access of air is not prevented. For it absorbs
oxygen and becomes insoluble; and its oxidation is
communicated to the alcohol, which is converted
into 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 effected without the alcohol undergoing
the same change, a higher temperature being neces-
sary to enable alcohol to combine with oxygen. As
long as the wine in ihe stilling-casks deposites yeast,
it can still be caused to ferment by the addition of
sugar, but old well-layed wine has lost this property,
because the condition necessary for fermentation,
namely, a substance in the act of decomposition or
putrefaction, is no longer present in it.

In hotels and other places where wine is drawn
gradually from a cask, and a proportional quantity
of air necessarily introduced, its eremacausis, that
is, its conversion into acetic acid, is prevented by
the addition of a small quantity of sulphurous acid.
This acid, by entering into combination 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.

348 FERMENTATION OF BEER.

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 without acidifying or experiencing any
change. This valuable quality is obtained for it by
a peculiar management of the fermentation of the
wort. The perfection of experimental knowledge
has here led to the solution of one of the most beau-
tiful problems of the theory of fermentation.

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 yeast, by which
they become specifically lighter than the liquid in
which they are formed, and rise to its surface. Glu-
ten in the act of oxidation comes in contact with
the particles of the decomposing sugar in the inte-
rior of the liquid. The carbonic acid from the sugar
and insoluble ferment from the gluten are disengaged
simultaneously, and cohere together.

A great quantity of gluten remains dissolved in
the fermented liquid, even after the transformation
of the sugar 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 completely 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

THE BAVARIAN PROCESS. 349

evolved during its continuance is not in large bub-
bles which burst upon the surface of the liquid, 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
difference 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 sugar goes on at the
same time, carbonic acid and yeast are simultane-
ously disengaged. It is known with certainty, that
this formation of yeast depends upon oxygen being
appropriated by the gluten in the act of decomposi-
tion ; but it has not been sufficiently shown, whether
this oxygen 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 oxida-
tion 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 decomposi-
tion, but is oxidized gluten, still capable of under-
going a new transformation by the transposition of
its constituent elements. By virtue of this condition
it has the power to excite fermentation in a solution
of sugar ; and if the gluten be also present, the
decomposing sugar induces its conversion into fresh
yeast, so that, in a certain sense, the yeast appears:
to reproduce itself.

350 FERMENTATION OF BEER.

Yeast of this kind is oxidized gluten in a state of
putrefaction, and by virtue of this state it induces
a similar transformation in the elements of the sup-ar.

The yeast formed during the fermentation of Ba-
varian beer is oxidized gluten in a state of decay.
The process of decomposition which its constituents
are suffering, gives rise to a very protracted putre-
faction {^fei^mentation) in the sugar. The intensity
of the action is diminished 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 gluten.

But the contact of the already decaying and pre-
cipitated gluten or yeast, causes the eremacausis of
the gluten 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
fermenting beer by filtration, without the fermenta-
tion being thereby arrested ; but precipitated yeast
of Bavarian beer cannot be removed without the
whole process of its fermentation being interrupted.
The beer ceases to ferment altogether, or, if the
temperature is raised, undergoes the ordinary fer-
mentation.

The precipitated yeast does not excite ordinary
fermentation, and consequently is quite unfitted for
the purpose of baking ; but the common frothy yeast
can cause the kind of fermentation by which the
former kind of yeast is produced.

When common yeast is added to wort at a tem-
perature of between 40^ and 45° F., a slow tranquil
fermentation 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 repeated several times in succession,
the ordinary fermentation changes into that process
by which only precipitated yeast is formed. The
yeast now deposited has lost the property of excit-

THE BAVARIAN PROCESS. 351

ing ordinary fermentation, but it produces the other
process even at a temperature of 50^ F.

In wort subjected to fermentation, at a low tem-
perature, 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, some-
thing more is required.

When the power of gluten to attract oxygen is
increased by contact with precipitated yeast in a
state of decay, the unrestrained access of air is the
only other condition necessary for its own conver-
sion 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 alcohol and its conver-
sion into acetic acid, but they are incapable of exert-
ing this influence at low temperatures. A low tem-
perature retards the slow combustion of alcohol,
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 placed in the same
condition as the gluten itself 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 nei-
ther of them, being altogether absorbed by the acid.
The same thing happens in the peculiar process of
fermentation adopted in Bavaria. The oxygen of
the air unites only with the gluten and not with the
alcohol, although it would have combined with both
at higher temperatures, so as to form acetic acid.

Thus, then, this remarkable process of fermenta-
tion with the precipitation of a mucous-like ferment
consists of a simultaneous putrefaction and decay in
the same liquid. The sugar is in the state of putre-
faction, and the gluten in that of decay.

352 FERMENTATION OF BEER.

Appert's method of preserving food, and this kind
of fermentation of beer, depend on the same prin-
ciple.

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 temperature is kept sufficiently low to prevent
the alcohol from combining with oxygen. The re-
moval of these substances diminishes the tendency
of the beer to become acescent, or, in other words,
to suffer a further transformation.

In Appert's mode of preserving food, oxygen is
allowed 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 tiompletion of the decay, every cause which could
effect further decomposition of the food is removed.
The conditions for putrefaction are rendered insuffi-
cient 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 to be uncertain, whether gluten
during its conversion into common yeast, that is,
into the insoluble state in which it separates from
fermenting liquids, really combines directly with
oxygen. If it does combine with oxygen, then the
difference between 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 bod-
ies contain the same elements as gluten, although in
different proportions. Now they are known to be
convertible into each other, by oxygen being absorb-
ed in the one case, and in the other extracted. Both

* Products of the decomposition of uric acid by nitric acid, consisting'
of carbon, nitrogen, hydrogen, and oxygen. See description, &c. in
Webster's Chemistry^ pp. 425 and 430.

FERMENTATION OF BEER. 353

are composed of absolutely the same elements, in
equal proportions ; with the single exception, that
alloxantin contains 1 equivalent of hydrogen more
than alloxan.

When alloxantin is treated with chlorine and ni-
tric 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 sulphuret-
ted 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 considered them as oxides of
the same radical : the alloxan being regarded as a
combination of a body composed of C^ N^ ff 0^ with
2 equivalents of water, and alloxantin as a combina-
tion of 3 atoms of water, with a compound consist-
ing of C^ N^ W 0^. The conversion of alloxan into
alloxantin would in this case result from its eight
atoms of oxygen being reduced to seven, while al-
loxan 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 al-
loxantin. But no compounds of hydrogen are known
which form hydrates ; and custom, which rejects all
dissimilarity until the claim to peculiarity is quite
proved, leads us to prefer an opinion, for which there
is no further foundation than that of analogy. The
woad [Isatis tinctoria) and several species of the
Nerium contain a substance similar in many respects
to gluten, which is 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 indigo 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 hydrogen more
than the blue.

30*

354 FERMENTATION OF BEER.

In the same manner the soluble gluten may be con-
sidered a compound of hydrogen, which becomes
ferment 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 con-
dition of gluten ; for yeast is not deposited on keep-
ing 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 di-
rectly 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 hydrogen, then this hydrogen must
be removed during the ordinary fermentation of must
and wort, by combining with oxygen, exactly as in
the conversion of alcohol into aldehyde * by erema-
causis.

In both cases the atmosphere is excluded; the
oxygen cannot, then, be derived from the air, neither
can it be supplied by the elements of water, for it is
impossible to suppose, that the oxygen will separate
from the hydrogen of water, for the purpose of unit-
ing with the hydrogen of gluten, in order again to
form water. The oxygen, must, therefore, be ob-
tained from the elements of sugar, a portion of which
substance must, in order to the formation of ferment,
undergo a different decomposition from that which
produces alcohol. Hence a certain part of the sugar
will not be converted into carbonic acid and alcohol,
but will yield other products containing less oxygen
than sugar itself contains. These products, as has
already been mentioned, are the cause of the great

* 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.

THE BAVARIAN PROCESS. 355

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 fer-
mentation, 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 ferment, 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 transforma-
tion of the sugar is not accompanied by the forma-
tion 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
added, the proportion of alcohol and carbonic acid
obtained during the fermentation of the mash corre-
sponds exactly to that of the carbon contained in
the starch. It is also known, that the volume of car-
bonic acid evolved during the fermentation of beet-
roots gives no exact indication of the proportion of
sugar contained in them, for less carbonic acid is
obtained than the same quantity of pure sugar would
yield.

Beer obtained by the mode of fermentation adopt-
ed in Bavaria contains more alcohol, and possesses
more intoxicating properties, than that made by the
ordinary method of fermentation, when the quanti-
ties of malt used are the same. The strong taste
of the former beer is generally ascribed to its con-
taining carbonic acid in larger quantity, and in a
state of more intimate combination ; but this opinion
is erroneous. Both kinds of beer are, at the conclu-
sion of the fermentation, completely saturated with
carbonic acid, the one as much as the other. Like
all other liquids, they both must retain such a por-
tion of the carbonic acid evolved as corresponds to
their power of solution, that is, to their volumes.

The temperature of the fluid during fermentation

356 FERMENTATION OF BEER.

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
950 (30^ to 350 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 di-
minishes in proportion as the temperature is lower.
But in vegetable juices, containing nitrogen, it is
impossible to fix a limit, where the transformation
of the sugar is undisturbed by any other process of
decomposition.

It is known, that in the fermentation of Bavarian
beer, the action of the oxygen of the air, and the
low temperature, cause complete transformation of
the sugar into alcohol ; the cause which would pre-
vent that result, namely, the extraction of the oxy-
gen of part of the sugar by the gluten, in its con-
version into ferment, being avoided by the introduc-
tion of oxygen from without.

The quantity of matters in the act of transforma-
tion is naturally greatest at the beginning of the
fermentation of must and wort ; and all the phenom-
ena which accompany 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 en-
tirely before the process can be regarded as com-
pleted.

The less rapid process of decomposition which
succeeds the violent evolution of gas, continues in
wine and beer until the sugar has completely dis-
appeared; and hence it is observed, that the specific
gravity of the liquid diminishes during many months.
This slow fermentation, in most cases, resembles the
fermentation of Bavarian beer, the transformation
of the dissolved sugar being in part the result of a
slow and continued decomposition of the precipita-

DECAY OF WOODY FIBRE. 357

ted yeast ; but a complete separation of the azotized
substances dissolved in it cannot take place when
air is excluded.*

Neither alcohol alone, nor hops, nor indeed both
together, preserve beer from becoming acid. The
better kinds of ale and porter in England are pro-
tected 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 man-
ner 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 sub-
stances being very great in proportion 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, to which free access
of the air is permitted.

CHAPTER X.

DECAY OF Vi^OODY FIBRE.

The conversion of woody fibre into the substances
termed humus and mould is, on account of its in-
fluence on vegetation, one of the most remarkable
processes of decomposition which occur in nature.

Decay is not less important in another point of

* The great influence which a rational management of fermentation
exercises upon the quahty of beer is well known in several of the Ger-
man states. In the grand-duchy of Hesse, for example, a considerable
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 intelligible by the
theory. — L.

358 DECAY OF WOODY FIBRE.

view ; for, by means of its influence on dead vege-
table matter, the oxygen which plants retained dur-
ing life is again restored to the atmosphere.

The decomposition of w^oody fibre is effected in
three forms, the results of which are different, so
that it is necessary to consider each separately.

The first takes place when it is in the moist con-
dition, and subject to free uninterrupted access of
air ; the second occurs when the air is excluded ;
and the third when the wood is covered with water,
and in contact with putrefying organic matter.

It is known that woody fibre may be kept under
water, or in dry air, for thousands of years without
suffering any appreciable change ; but that when
brought into contact with air, in the moist con-
dition it converts the oxygen surrounding it into the
same volume of carbonic acid, and is itself gradually
changed into a yellowish brown, or black matter, of
a loose texture.*

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, be-
sides its essential constituents.

The relative proportions of the component elements
are, 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 triv-
ial, that it may be altogether neglected in the con-
sideration of the questions which will now be brought
under discussion ; besides, the quantity of the for-
eign substances is not constant, Ijut varies according
to the season of the year.

* According to the experiments of De Saussure, 240 parts of dry
saw-dust of oak wood convert 10 cubic inches of oxygen into the same
quantity of carbonic acid, which contains 3 parts, by weight, of car-
bon ; 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. — L.

DECAY OF WOODY FIBRE. 359

According to the careful analysis of Gay-Lussac
and Thenard, 100 parts of oak wood, dried at 212^
(100^ C), from which all soluble substances had
been extracted by means of water and alcohol, con-
tained 52-53 parts of carbon, and 47*47 parts of hy-
drogen and oxygen, 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 di-
rectly with oxygen, and that the products of this
action are carbonic acid and humus.

If the action of the oxygen were confined to the
carbon of the wood, and if nothing but carbon were
removed from it, the remaining elements would ne-
cessarily be found in the humus, unchanged except
in the particular of being combined with less carbon.
The final result of the action would therefore be a
complete disappearance of the carbon, whilst noth-
ing but the elements of water would remain.

But when decaying wood is subjected to exami-
nation in different stages of its decay, the remark-
able 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
possessed a chocolate brown color and the structure
of wood, showed that 100 parts of it contained 53*56
parts of carbon and 46*44 parts of hydrogen and
oxygen in the same relative proportions as in w^ater.
From an examination of mouldered wood of a light-
brown color, easily reducible to a fine powder, and
taken from another oak, it appeared that it contained
56-211 carbon and 43*789 water.

These indisputable facts point out the similarity
of the decay of wood, with the slow combustion or
oxidation of bodies which contain a large quantity

360 DECAY OF WOODY FIBRE.

of hydrogen. Viewed as a kind of combustion, it
would indeed be a very extraordinary process, if the
carbon combined directly wdth 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 hy-
drogen 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 com-
bines at common temperatures with oxygen, so as to
form carbonic acid.

In whatever stage of decay wood may be, its ele-
ments * 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 Th^nard.*
C 35 H20 O 20 — humus from oak wood (Meyer). t
C34 H18 018— *' " (Dr. Will)4

It is evident from these numbers, that for every
two equivalents of hydrogen which are 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 tempera-
ture and free unrestrained access of air. The decay,
on the contrary, is much retarded by absence of
moisture, and by the wood being surrounded w^ith
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 corrosive 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

* The calculation gives 52-5 carbon, and 47-5 water,
t The calculation gives 54 carbon, and 46 water.
t The calculation gives 56 carbon, and 44 water.

WOODY FIBRE. 361

their property of entering into fermentation, putre-
faction, or decay.*

But the decay of woody fibre is very much accel-
erated by contact with alkalies or alkaline earths ;
for these enable substances to absorb oxygen, which
do not possess this power themselves ; alcohol,
gallic acid, tannin, the vegetable coloring matters,
and several other substances, are thus affected by
them. Acids produce quite an opposite eflfect ; they
greatly retard decay.

Heavy soils, consisting of loam, retain longest the
most important condition for the decay of the vege-
table matter contained in them, viz., water; but
their impermeable nature prevents contact with the
air.

In moist sandy soils, particularly such as are com-
posed 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 carbonic acid. It is evident, that if we
subtract from the formula C^% W^, 0^^, the 22 equiv-
alents of oxygen, with 11 equivalents of carbon, and
22 equivalents of hydrogen, which are supposed to
be oxidized by the oxygen 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
reason, that with the increase of the proportion of

* See an account of the process for *' kyanizing" timber in the Farm-
fir's Register, Vol. III. p. 368.

362 DECAY OF WOODY FIBRE.

carbon in the residual humus, as in all decomposi-
tions of this kind, its attraction for the hydrogen,
which still remains in combination, also increases,
until at length the affinity of oxygen for the hydro-
gen is equalled by that of the carbon for the same
element.

In proportion as the decay of woody fibre ad-
vances, 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 should naturally expect that the flame given
out by decayed wood would be more brilliant, in
proportion to the increase of its carbon; but we find,
on the contrary, 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 supposed to be in the state of water;
for had it any other form, the characters we have de-
scribed 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
manner similar to the production of the crystalline
colorless naphthalin from a gaseous compound of
carbon and hydrogen. 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 ac-
counting for the origin and formation of diamonds,

VEGETABLE MOULD. 363

except the process of decay. Diamonds cannot be
produced by the action of fire, for a high temperature
and the presence of oxygen gas, would call into
play their combustibility. 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
decomposition. They are found in wood or brown
coal, and have evidently proceeded from the decom-
position of substances which were contained in quite
a different form in the living plants. They are all
distinguished by the proportionally small quantity
of hydrogen which they contain. The acid from
mellite (mellitic acid) contains precisely the same
proportions of carbon and oxygen as that from
amber (succinic acid); they differ only in the pro-
portion of their hydrogen. M. Bromeis* found, that
succinic acid might be artificially formed by the
action of nitric acid on stearic acid, a true process
of eremacausis ; the experiment was made in this
laboratory (Giessen).

CHAPTER XL

VEGETABLE MOULD.

The term vegetable mouldy in its general significa-
tion, is applied to a mixture of disintegrated miner-
als, with the remains of animal and vegetable sub-
stances. It may be considered as earth in which
humus is contained in a state of decomposition. Its
action upon the air has been fully investigated by
Ingenhouss and De Saussure.

When moist vegetable mould is placed in a vessel

^^■^^ ■ II ■■—■■■■■ , I ■■^— I -I ■—■■■■■ I ■ .^i.i ■ ■ ■■■ ■ ^ . _■ .11 . ^— ^^i^p^^

* Liebig's Annalen, Band xxxiv., heft 3.

364 VEGETABLE MOULD.

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 repeated.

Cold water dissolves only icoogth of its own weight
of vegetable mould ; and the residue left on its
evaporation 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 sub-
stances 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 solution is
evaporated, a residue is left which becomes black on
being heated to redness, and afterwards yields car-
bonate of potash when treated with water.

A solution of caustic potash becomes black when
placed in contact with vegetable mould, and the ad-
dition of acetic acid to the colored solution causes no
precipitate or turbidness. But dilute sulphuric acid
throws down 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 pre-
cipitate, 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 solu-
bility to the presence of the alkaline salts contained
in the remains of plants. This substance is a pro-
duct of the incomplete decay of woody fibre. Its
composition is intermediate between woody fibre and
humus, into which it is converted, by being exposed
in a moist condition to the action of the air.

DECOMPOSITION OF WOOD, COAL, ETC. 365

CHAPTER XIL

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 mould-
ering.

Wood, or brown coal and mineral coal, are the re-
mains of vegetables of a former world; their ap-
pearance and characters show, that they are products
of the processes of decomposition termed decay and
putrefaction. We can easily ascertain by analysis
the manner in which their constituents have been
changed, if we suppose 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 con-
sider a peculiar change which woody fibre suffers by
means of moisture, when partially or entirely ex-
cluded from the air.

It is known, that when pure woody fibre, as linen,
for example, is placed in contact w^ith water, con-
siderable 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 putre-
faction takes place, the wood assumes a white color,
loses its peculiar texture, and is converted into a
rotten friable matter.
31*

366 DECOMPOSITION OF WOOD, COAL, ETC.

The white decayed wood found in the interiors 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^,

. 48-14
606

. 44-43
1-37

Carbon

48-11

Hydrogen

6-31

Oxygen
Ashes

45-31

1-27

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, in-
creased. The numbers obtained by the analysis cor-
respond very nearly to the formula C33 H27 024.*

The elements of water have, therefore, become
united with the wood, whilst carbonic acid is disen-
gaged by the absorption of a certain quantity of
oxygen.

If the elements of 5 atoms of water and 3 atoms
of oxygen be added to the composition of the woody
fibre of the oak, and 3 atoms of carbonic acid de-
ducted, 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 O 30
Subtract from this 3 atoms carbonic acid C 3 O 6

C33 H27 024

The process of mouldering is, therefore, one of
putrefaction and decay, proceeding simultaneously,
in which the oxygen of the air and the component

* The calculation from this formula gives in 100 parts 47-9 carbon,
6-1 hydrogen, and 46 oxygen.

DECOAIPOSITION OF WOOD, COAL, ETC. 367

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 yielded on analysis 47*67
carbon, 5*67 hydrogen, and 46*68 oxygen ; this cor-
responds 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 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, w^hich forms extensive layers in

the Wetterau (a district in Hesse Darmstadt), is

distinguished from that found in other places, by

possessing the structure of wood unchanged, and by

containing no bituminous matter. This coal was

subjected to analysis, a piece being selected upon

which the annual circles could be counted. It was

obtained from the vicinity of Laubach ; 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 evi-
dent, that the wood which has undergone the change
into coal must have parted with a certain portion of

368 DECOMPOSITION OF WOOD, COAL, ETC.

its oxygen. The proportion of these numbers is
expressed by the formula C33 H21 016.*

When these numbers are compared with those
obtained 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.

1 atom wood , C36 H22 022

Minus 1 atom hydrogen and 3 atoms car- ^ r; q h i o 6
bonic acid S

Wood Coal . . C33 H21 016

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 decom-
position. The excess of hydrogen is either hydro-
gen of the wood which has remained in it unchanged,
or it is derived from some exterior 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
Hydrogen
Oxygen
Ashes

100-00 100-00

The proportions derived from these numbers cor-
respond very closely to the formula C^^ H^^ 0% or
they represent the constituents of wood, from which
the elements of carbonic acid, water, and 2 equiva-
lents hydrogen, have been separated.

C36H22 022=Wood.
Subtract C 4 H 7 013 = 4 atoms carbonic acid -}-5 atoms of water

-j" 2 atoms of hydrogen.

C32 H15 O 9 = Wood coal from Ringkuhl.

The formation of both these specimens of wood
* The calculation gives 57-5 carbon, and 5-98 hydrogen.

62-60

6383

502

. 4-80

26-52

25-51

5-86

. 5-86

FORMATION OF WOOD COAL. 369

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 is covered with a layer of basalt,
and the coal of Ringkuhl 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 quan-
tity of water. It is quite possible, that the difference
in the process of decomposition may depend upon
the high temperature 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 temperature of from 334° to 352° F.
(150°— 160° C), and under a corresponding pres-
sure. The ashes of the wood amounted to 0*51 per
cent. ; a little less, therefore, than those of the Lau-
bacher coal ; but this must be ascribed to the pecu-
liar 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 disengagement of carbonic acid from their sub-
stance, appears still to go on at great depths in all
the layers of wood coal. At all events it is remark-
able, that springs impregnated with carbonic acid
occur in many places, in the country between Meiss-
ner, in the electorate of Hesse, and the Eifel, which
are known to possess large layers of wood coal.
These springs of mineral water are produced on the
spot at which they are found ; the springs of com-

370 CONVERSION OF WOOD

mon water meeting with carbonic acid during their
ascent, and becoming impregnated with it.

In the vicinity of the layers of wood coal at Salz-
hausen (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 dis-
appeared, and in its place is found a spring of com-
mon water.

Springs of water impregnated with carbonic acid
occur at Schwalheim, at a very short distance from
the layers of wood coal at Dorheim. M. Wilhelmi
observed some time since, that they are formed of
common 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 BischofF, seldom mixed with
nitrogen or oxygen, and is probably produced in a
manner similar to that just described. At any rate
the air does not appear to take any part in the for-
mation of these acidulous springs. Their carbonic
acid has evidently not been formed either by a com-
bustion at high or low temperatures ; for if it were
so, the gas resulting from the combustion would ne-
cessarily be mixed with | of nitrogen, but it does
not contain a trace of this element. The bubbles of
gas which escape from these springs are absorbed
by caustic potash, with the exception of a residuum
too small to be appreciated.

The wood coal of Dorheim and Salzhausen must
have been formed in the same way as that of the
neighboring village of Laubach ; and since the latter
contains the exact elements of woody fibre, minus a

INTO BROWN OR WOOD COAL. 371

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 in-
cessant 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 car-
bonic acid in the mines.

The gases which are formed in mines of wood coal,
and cause danger in their working, are not combus-
tible or inflammable as in mines of mineral coal ;
but they consist generally of carbonic acid gas, and
are very seldom 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
(sulphuret of zinc); which minerals are still formed
from salts of sulphuric acid, with iron or zinc, during
the putrefaction of all vegetable matter. It is pos-
sible, that the 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.

According to the analysis of Richardson and Reg-
nault, the composition of the combustible materials
in splint coal from Newcastle, and cannel coal from
Lancashire, is expressed by the formula C24 H13 O.
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 quan-
tity of carburetted hydrogen and carbonic acid in

* The analysis of brown coal from Ringkuhl, as well as all those of
the same substance given in this work, have been executed in this labo-
ratory by M. Kiihnert of Cassel. — L.

372 CONVERSION OF WOOD INTO MINERAL COAL.

the form of combustible 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.

C36H22 022 = wood

C12 H9 021

3 atoms of carburetted hydrogen C 3 H6
3 atoms of water . . H 3 03

9 atoms of carbonic acid . C 9 018

Mineral coal C24 H13 O

Carburetted hydrogen generally accompanies all
mineral coal; other varieties of coal contain volatile
oils, which may be separated by distillation with
water. (Reichenbach.) The origin of naphtha is
owing to a similar process of decomposition. Caking
coal from Caresfield, near Newcastle, contains the
elements of cannel coal, minus the constituents of
defiant gas C4 H4.

The inflammable gases which stream out of clefts
in the strata of mineral coal, or in rocks of the coal
formations, always contain carbonic acid, according
to a recent examination by BischofF, and also car-
buretted hydrogen, nitrogen, and defiant gas ; the
last of which had not been observed, until its ex-
istence in these gases was pointed out by Bischoff.
The analysis of fire-damp, after it had been treated
with caustic potash, showed its constituents to be.

Gas from an

abandoned Gerbard's pas- Gas from a

mine near sage near Lu- mine near

Wallesweiler. isenthal. Liekwege.

Vol. Vol. Vol.

Light carburetted hydrogen 91-36 8308 79-10

defiant gas. . 6-32 1-98 16-11

Nitrogen gas . . 2-32 14-94 4-79

100-00 10000 10000

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

POISONS, CONTAGIONS, MIASMS. 373

of mineral coal. Hydrogen, on the contrary, is dis-
engaged from the constituents of mineral coal in the
form of a compound of carbo-hydrogen ; a complete
removal of all the hydrogen would convert coal into
anthracite.

The formula C36 H22 022, which is given for
wood, has been chosen as the empirical expression
of the analysis, for the purpose of bringing all the
transformations, 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 constitution 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 theoretical expression refers to
the quantity, the empirical merely to the relative pro-
portion in which the elements of a body are united.
Whatever form the first may assume, the empirical
expression must always remain unchanged.

CHAPTER Xm.

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 ac-
tion attains a certain degree of intensity, death is
the consequence.

The action of inorganic compounds, such as acids,
alkalies, metallic oxides, and salts, can in most cases
be easily explained. They either destroy the con-
tinuity of particular organs, or they enter into com-

374 POISONS, CONTAGIOxNS, MIASMS.

bination with their substance. The action of sul-
phuric, 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 injury on par-
ticular 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 con-
stituents 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 sub-
stances in general, in order to obtain a clear con-
ception of the mode of action of those which are
poisonous. We find that certain soluble compounds,
when presented to different parts of the body, are
absorbed by the blood, whence they are again elim-
inated by the organs of secretion, either in a changed
or in an unchanged state.

Iodide of potassium, sulpho-cyanuret of potassium,
ferro-cyanuret of potassium, chlorate of potash, sili-
cate of potash, and all salts with alkaline bases,
when administered internally to man and animals in
dilute solutions, or applied externally, may be again
detected in the blood, sweat, chyle, gall, and splenic
veins ; but all of them are finally excreted from the
body through the urinary passages.

Each of these substances, in its transit, produces
a peculiar disturbance in the organism, — in other
words, they exercise a medicinal action upon it, but
they themselves suffer no decomposition. If any of
these substances enter into combination with any
part of the body, the union cannot be of a perma-
nent kind ; for their reappearance in the urine shows

EFFECTS OF SALTS ON THE ORGANISM. 375

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 carbonic acid which has united
with the bases. (Gilbert Blane and Wohler.)

The conversion of these salts of organic acids
into carbonates, indicates that a considerable quan-
tity of oxygen must have united with their elements.
In order to convert 1 equivalent of acetate of potash
into the carbonate of the same base, 8 equivalents
of oxygen must combine with it, of which either 2
or 4 equivalents (according as an acid or neutral
salt is produced) remain in combination with the
alkali ; whilst the remaining 6 or 4 equivalents are
disengaged as free carbonic acid. There is no evi-
dence presented by the organism itself, to which
these salts have been administered, that any of its
proper constituents have yielded so great a quantity
of oxygen as is necessary for their conversion into
carbonates. Their oxidation can, therefore, only be
ascribed to the oxygen of the air.

During the passage of these salts through the
lungs, their acids take part in the peculiar process
of eremacausis which proceeds in that organ; a cer-
tain quantity of the oxygen gas inspired unites with
their constituents, and converts their hydrogen into
water, and their carbon into carbonic acid. Part 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 separated by
the kidneys or liver.

It is manifest, that the presence of these organic
salts in the blood must produce a change in the pro-
cess of respiration. A part of the oxygen inspired,
which usually combines with the constituents of the
blood, must, when they are present, combine with

376 POISONS, CONTAGIONS, MIASMS.

their acids, and thus be prevented from performing
its usual office. The immediate consequence of this
must be the formation of arterial blood in less quan-
tity, or in other words, the process of respiration
must be retarded.

Neutral acetates, tartrates, and citrates placed in
contact with the air, and at the same time with
animal or vegetable bodies in a state of eremacausis,
produce exactly the same effects as we have de-
scribed them to produce in the lungs. They partici-
pate in the process of decay, and are converted into
carbonates just as in the 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 disap-
pear.

Free mineral acids, or organic acids which are not
volatile, and salts of mineral acids with alkaline
bases, completely arrest decay when added to decay-
ing 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 neutral organic salts, but
their action depends upon a different cause.

The absorption by the blood of a quantity of an
inorganic 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 permeated 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 satu-
rated solutions of common salt, nitre, ferro-cyanuret
of potassium, sulpho-cyanuret of potassium, sulphate
of magnesia, 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.

EFFECTS OF SALTS ON THE ORGANISM. 377

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
I thereby lost the power of penetrating animal sub-
stances, it has on this account separated from the
flesh. The water still retained by the flesh contains
a proportionally small quantity 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, ani-
mal tissues, 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
dilution, is introduced into the stomach, it is ab-
sorbed ; but a concentrated saline solution, in place
of being itself absorbed, extracts water from the
organ, and a violent thirst ensues. Some inter-
change of water and salt takes place in the stomach ;
the coats of this viscus yield water to the solution,
a part of which having previously become sufficiently
diluted, is, on the other hand, absorbed. But the
greater part of the concentrated solution of salt
remains unabsorbed, and is not removed by the
urinary passages ; it consequently enters the intes-
tines and intestinal canal, where it causes a dilution
of the solid substances deposited there, and thus
acts as a purgative.

Each of the salts just mentioned possesses this
purgative action, which depends on a physical prop-
erty shared by all of them; but besides this they
exercise a medicinal action, because every part of
32*

378 POISONS, CONTAGIONS, MIASMS.

the organism with which they come in contact ab-
sorbs a certain quantity of them.

The composition of the salts has nothing to do
with their purgative action ; it is quite a matter of
indifference as far as the mere production of this
action is concerned (not as to its intensity), whether
the base be potash or soda, or in many cases lime
and magnesia; and whether the acid be phosphoric,
sulphuric, nitric, or hydrochloric.

Besides, these salts, the action of which does not
depend upon their power of entering into combina-
tion 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 per-
manent compounds with the substance of the mem-
branes, and muscular fibre.

Salts of lead, iron, bismuth, copper, and mercury,
belong to this class.

When solutions of these salts are treated with a
sufficient quantity of albumen, milk, muscular fibre,
and animal 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
combination with the membranes, cellular tissue, and
muscular fibre ; but in very few cases can they reach
the blood. All experiments instituted for the pur-
pose of determining whether they pass into the urine

INORGANIC POISONS. 379

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 putrefac-
tion. Wood and cerebral substance are both bodies
which undergo change with great rapidity and facili-
ty when subject to the influence 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 influences 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 combina-
tion 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
sublimate are not prevented by the vital principle
from entering 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 suffer-
ing and eff*ecting transformations ; or, in other words,
organic life must be destroyed. If the poisoning is
merely superficial, and the quantity of the poison so
small that only individual parts 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 considerations it
may readily be inferred, that all internal signs of

380 POISONS, CONTAGIONS, MIASMS.

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,
because, 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 be-
come poisoned.

The compounds of arsenic, which have not the
property of entering into combination with the tis-
sues 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 Bunsen,
has not the slightest injurious action upon the organ-
ism ; yet it contains a very large quantity of arsenic,
and approaches very closely in composition to the
organic arsenious compounds found in the body.

These considerations enable us to fix with tolera-
ble certainty the limit at which the above substances
cease to act as poisons. For since their combina-
tion 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 quantity, a part of the organ will
retain its vital functions.

According to the experiments of Mulder,* the
equivalent 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, approximatively, that a quantity of fibrin
corresponding to the number 6361 combines with 1
equivalent of arsenious acid, or 1 equivalent of cor-
rosive sublimate.

When 6361 parts of anhydrous fibrin are combined

* PoggendorfTs Annalen, Band xl. S. 259.

INORGANIC POISONS. 381

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 animal p-elatin 5652.

100 grains of albumen containing all the water
with which it is combined in the living body, should
consequently combine with 1^ grain of arsenious
acid.

These proportions, which may be considered as
the highest which can be adopted, indicate the re-
markably high atomic weights of animal substances,
and at the same time teach us, what very small quan-
tities of arsenious acid or corrosive sublimate are
requisite to produce 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 combination with animal matters, and
of thus acting as poisons. Unfortunately no other
body surpasses them in that power, and the com-
pounds which they form can only be broken up by
affinities so energetic, that their action is as injuri-
ous as that of the above-named poisons themselves.
The duty of the physician consists, therefore, 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 inca-
pable of being decomposed or digested in the same
conditions. Hydrated peroxide of iron is an inval-
uable substance for this purpose.*

When the action of arsenious acid or corrosive
sublimate is confined to the surface of an organ,

** On the preparation, &c., of this antidote, see Appendix.

382 POISONS, CONTAGIONS, MIASMS.

those parts only are destroyed which enter into com-
bination with it; an eschar is formed, which is grad-
ually 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,
unless 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 substances, 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 putrefaction.

When nitrate of silver in a state of solution is
applied to skin or muscular fibre, it combines with
them instantaneously; animal substances dissolved
in any liquid are precipitated by it, and rendered
insoluble, or, as it is usually termed, they are coagu-
lated. The compounds thus formed are colorless,
and so stable, that they cannot be decomposed by
other powerful chemical agents. 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 organ-
ism, for their vital functions have been arrested by
combination with oxide of silver ; and if they are
capable of being reproduced, the neighboring 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 im-
mediately converted into chloride of silver, — a sub-
stance which is absolutely insoluble in pure water.
In a solution of salt or muriatic acid, however,
chloride of silver does dissolve in extremely minute
quantity ; and it is this small part which exercises
a medicinal influence when nitrate of silver is admin-
istered ; the remaining chloride of silver is elimi-

INORGANIC POISONS. 383

nated 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 incapa-
ble of permitting liquids to penetrate through their
pores. A strong contraction and shrinking of the
surface is the general effect of contact with these
metallic bodies. But corrosive sublimate, and several
of the salts of lead, possess a peculiar 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 combina-
tion with the most powerful acids, are reduced by
many vegetable substances, particularly such as sugar
and honey, either into metallic copper, or into the
red suboxide, neither of which enters into combina-
tion with animal matter. It is well known that sugar
has been long employed as the most convenient
antidote for poisoning by copper.

With respect to some other poisons, namely, hy-
drocyanic acid and the organic bases strychnia and
brucia, we are acquainted with no facts calculated to
elucidate the nature of their action. It may, how-
ever, be presumed with much certainty, that experi-
ments upon their mode of action on different animal

384 POISONS, CONTAGION^, MIASMS.

substances would very quickly lead td the most
satisfactory conclusions regarding 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 combination with it, or by reason of their con-
taining a poisonous material, but solely by virtue of
their peculiar condition.

In order to attain a clear conception of the mode
of action of these bodies, it is necessary to call to
mind the cause on which we have shown the phe-
nomena of fermentation, 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 phenom-
ena has only lately been proved. " A molecule set
in motion by any power can impart its own m^otion to
another molecule with which it may be in cotitact.^^

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 sufficient to overcome it.

We have seen that ferment or yeast is a body in
the state of decomposition, the atoms of which, con-
sequently, 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 in
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

PUTRID POISONS. 385

state of decomposition from the yeast just mentioned.
Thus, when sugar is acted on by rennet or putrefy-
ing 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
solution of pure sugar gradually disappears, but that
when added to vegetable juices which contain gluten
as well as sugar, it is reproduced by the decomposi-
tion of the former substance.

The yeast with which these liquids are made to
ferment, has itself been originally produced from
gluten.

The conversion of gluten into yeast in these veg-
etable juices is dependent on the decomposition
(fermentation) 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 fermen-
tation in a fresh solution of sugar, and if this second
saccharine fluid should contain gluten, (should it be
wort^ for example,) yeast is again generated in con-
sequence of the transposition of the elements of the
sugar exciting a similar change in this gluten.

After this explanation, the idea that yeast repro-
duces 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 constit-
uents are contained, 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 effected when
the liquid acted upon contains the body by the met-
33

386 POISONS, CONTAGIONS, MIASMS.

amorphosis of which the exciter has been originally
formed.

It is also obvious, that if the exciter be able to
impart its own state of transformation to one only
of the component parts of the mixed liquid acted
upon, its own reproduction may be the consequence
of the decomposition of this one body.

This law may be applied to organic substances
forming 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 exist-
ing matters.

Nature has adapted the blood for the reproduction
of every individual part of the organism ; its princi-
pal character consists in its component parts being
subordinate to every attraction. These are in a per-
petual state of change or transformation, which is
effected in the most various ways through the in-
fluence of the different organs.

The individual organs, such as the stomach, cause
all the organic substances conveyed to them which
are capable of transformation to assume new forms.
The stomach compels the elements of these sub-
stances to unite into a compound fitted for the for-
mation 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 com-
pared in this respect with it.

Now it is a well-known fact, that when blood,
cerebral 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 living body, the smallest cut with a knife,
which has been used in their dissection, producing
in these cases dangerous consequences.

PUTRID POISONS. 387

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 Wurtemberg, especially, these
cases are very frequent, for there the sausages are
prepared from very various materials. Blood, liver,
bacon, brains, milk, meal, and bread, are mixed to-
gether 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 de-
ficient, and particularly when they are smoked too
late or not sufficiently, 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 under-
gone putrefaction, and they are found to contain free
lactic acid, or lactate of ammonia, products which
are universally formed during the putrefaction of
animal and vegetable matters.

The cause of the poisonous nature of these sau-
sages 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 in common ; and the
symptoms produced are sufficient to show that hy-
drocyanic acid is not the poison.

The death which is the consequence of poisoning
by putrefied sausages succeeds very lingering and
remarkable 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 carcass is stiff as if frozen, and is not
subject to putrefaction. During the progress of the

388 POISONS, CONTAGIONS, MIASMS.

disease the saliva becomes viscous and acquires an
offensive smell.

Experiments have been made for the purpose of
ascertaining 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 them-
selves acquiring similar properties.

Now this is the peculiar character of all substances
which exert an action by virtue of their existing
condition, — of those bodies the elements of which
are in the state of decomposition or transposition ; a
state which is destroyed by boiling water and alco-
hol without the cause of the influence being imparted
to those liquids; for a state of action or power can-
not be preserved in a liquid.

Sausages, in the state here described, exercise an
action upon the organism, in consequence of the
stomach and other parts with which they come in
contact not having the power to arrest their decom-
position ; 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 small-
pox virus are. All the substances in the body capa-
ble of putrefaction 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 incapable of putrefying in the
conditions afforded by the body.

It is impossible to mistake the modus operandi of
this poison, for Colin has clearly proved that mus-
cle, urine, cheese, cerebral substance, and other
matters, in a state of putrefaction, communicate
their own state of decomposition to substances much
less prone to change of composition than the blood.
When placed in contact with a solution of sugar,

MORBID POISONS. . 389

they cause its putrefaction, or the transposition of
its elements into carbonic acid and alcohol.

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 putrefaction to the sound blood from
which they were produced^ exactly in the same man-
ner 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 small-pox,
plague, and syphilis, substances of a peculiar na-
ture are formed from the constituents of the blood.
These matters are capable 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 containing sugar and gluten, that the two
processes have been long since compared to one
another, although merely for the purpose of illustra-
tion. But when the phenomena attending the action
of each respectively are considered 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 decomposition without destroying it ;
in the latter, all the circumstances necessary for the
completion of their decomposition are presented.

The temperature at which water boils, and contact
with alcohol, render such poisons inert. Acids, salts
of mercury, sulphurous acid, chlorine, iodine, bro-

33*

390 POISONS, CONTAGIONS, MUSMS.

mine, aromatic substances, volatile oils, and partic-
ularly empyreumatic oils, smoke, and a decoction of
coffee, completely destroy their contagious properties,
in some cases combining with them or otherwise
effecting their decomposition. 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 small-pox
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 mat-
ters, a peculiar principle of life has been ascribed to
them, — a life similar to that possessed by the germ
of a seed, which enables it under favorable condi-
tions to develop and multiply itself. It would be
impossible to find a more correct figurative repre-
sentation of these phenomena; it is one which is
applicable to contagions, as well as to ferment, to
animal and vegetable substances in a state of fer-
mentation, putrefaction or decay, and even to a piece
of decaying wood, which by mere contact with fresh
w^ood, 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
reproduction of itself, with all its properties, be
regarded as life, then, indeed, all the above phenom-
ena may be ascribed to life. But in that case they
must not be considered as the only processes due to
vitality, for the above interpretation of the expres-
sion 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.

MORBID POISONS. 391

If a body A, for example oxamide (a substance
scarcely soluble in water, and without the slightest
taste), be brought into contact with another com-
pound B, which is to be reproduced; and if this
second body be oxalic acid dissolved in water ; then
the following changes are observed to take place: —
The oxamide is decomposed by the oxalic acid,
provided the conditions necessary for their exercis-
ing an action upon one another are present. The
f elements of water unite with the constituents of
oxamide, and ammonia is one product formed, and
j axalic 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
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 matters 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 decomposition.

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 en-
ters into combination, whilst another portion is
liberated. In this manner a very minute quantity
of oxalic acid may be made to effect the decomposi-
tion 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 small-
pox causes such a change in the blood, as gives rise
to the reproduction of the poison from the constitu-
ents of the fluid. This transformation is not arrested
until all the particles of the blood which are suscep-
tible of the decomposition have undergone the met-

392 POISONS, CONTAGIONS, MIASMS.

araorphosis. We have just seen that the contact of
oxalic acid with oxaraide 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 belong to the
same class. But no one except a person quite unac-
customed to view such changes will ascribe them to
a vital power, although we admit they correspond
remarkably 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 exercised hy virtue of a definite form, and
production and generation in 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 tissue, no organic cell.

The production of organs, the cooperation of a
system of organs, and their power not only to pro-
duce 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 exist-
ence of this cause itself we are made aware only by
the phenomena 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, mechan-
ical motion, and friction. By the influence of the
latter forces, they suffer changes in their direction,
an increase or diminution of their intensity, or a
complete cessation or reversal of their action.

THEIR MODE OF ACTION. 393

Such an influence and no other is exercised by the
vital principle over the chemical forces ; but in every
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 organs in which it resides. Hence, whatever
kind of energy 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, electricity, or other influences may in-
crease, diminish, or arrest this action, but they are
not its efficient cause.

In the same way the vital principle governs the
chemical powers in the living body. All those sub-
stances 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 other resistance to overcome, in 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 pos-
sessed life, not merely the chemical forces, but this
vitality, would offer resistance 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 complex, and are held together only by a
weak chemical action. They are formed by the union
of two or more simple compounds ; and in propor-
tion as the number of their atoms augments, their
disposition to enter into new combinations is dimin-
ished ; that is, they lose the power of acting chem-
ically 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 ex-
ternal agency, in many cases even mechanical friction,
is sufficient to cause a disturbance in the equilibrium

394 POISONS, CONTAGIONS, MIASMS.

of the attraction of their constituents ; they arrange
themselves either into new, more simple, and perma-
nent combinations, or if a foreign attraction exercise
its influence upon it, they arrange themselves in
accordance with that attraction.

The special characters of food, that is, of substan-
ces fitted for assimilation, are absence of active
chemical properties, and the capability of yielding
to transformations.

The equilibrium in the chemical attractions of the
constituents of the food is disturbed by the vital
principle, as we know it may be by many other causes.
But the union of its elements, so as to produce new
combinations and forms, indicates the presence of a
peculiar mode of attraction, and the existence of a
power distinct from all other powers of nature,
namely, the vital principle.

All bodies of simple composition possess a greater
or less disposition to form combinations. Thus oxalic
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 disposition, 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 neutraliza-
tion and renewal 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.

THEIR MODE OF ACTION. 395

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 peculiar character of such a body
to be an aptitude and power to enter into combina-
tions 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 respec-
tive actions ; either an equilibrium of both powers is
attained, a change being effected without the de-
struction of the vital principle, in which case a medi-
dual effect is occasioned; 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.

Bodies of another class 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 in the system, either by their presence,
or by themselves undergoing a change ; these are
medicaments.

Compounds of a third class are called poisons,
when they possess the property of uniting with or-
gans or with their component parts, and when their
power of effecting this is stronger than the resis-
tance offered by the vital principle.

The quantity of a substance and its condition must
obviously completely change the mode of its chemi-
cal action.

Increase of quantity is known to be equivalent to
superior affinity. Hence a medicament administered
in excessive quantity may act as a poison, and a
poison in small doses as a medicament.

396 POISONS, CONTAGIONS, MIASMS.

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 con-
dition 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 par-
tial change.

No other component part of the organism can be
compared to the blood, in respect of the feeble re-
sistance 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 equilibrium, 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, that it cannot be removed from
the body without immediately 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.
Every 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 equilibrium between the chemical force
and the vital principle in the circulating fluid.
Numerous modifications in the composition and con-
dition of the compounds produced from the elements
of the blood, result from the conflict of the vital
force with the chemical aflSnity, in their incessant
endeavor to overcome one another.

THEIR MODE OF ACTION. 397

All the characters of the phenomena of contagion
tend to disprove the existence of life in contagious
matters. They without doubt exercise an influence
very similar to some processes in the living organ-
ism; 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
disease lose all their power when introduced into
the stomach, 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 fever in cattle [typhus contagiosus
ruminantium), or that of the smallpox, lose their
whole power of contagion in the stomach ; whilst
that of sausages, which has an acid reaction, retains
all its frightful properties under the same circum-
stances.

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 ma-
lignant putrefying pus, in the matter of vaccine, &c.
The presence of these bodies has given weight to
the opinion, that contagion proceeds from the de-
velopment of a diseased organic life ; and these for-
mations have been regarded as the living seeds of
disease.

This view, which is not adapted to 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 com-
posed of animals or plants, which nourish themselves
from the sugar in which they are placed, and at the

398 POISONS, CONTAGIONS, MIASMS.

same time yield alcohol and carbonic acid as excre-
mentitious matters.*

It would perhaps appear wonderful if bodieS; pos-
sessing a crystalline structure and geometrical figure,
were formed during the processes of fermentation
and putrefaction from the organic substances and
tissues of organs. We know, on the contrary, that
the complete dissolution into organic compounds is
preceded by a series of transformations, in which
the organic structures 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 glob-
ules have taken no part in the process of decompo-
sition. All the phosphate 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 consist merely
of a skeleton of phosphate of lime, but they will still
possess their original form. In the same way pro-
cesses of decomposition in the blood may aflect in-
dividual constituents only of that fluid, which will
become 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
mentioned, we must ascribe life to a gas, that is, to
an aeriform body.

All the supposed proofs of the vitality of con-
tagions are merely ideas and figurative representa-
tions, 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 the/a^a morgana, which show us deceitful

* Annalen der Pharmacie, Band xxix. S. 93 und 100.

THEIR MODE OF ACTION. 399

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, and in no way connected with the vital prin-
ciple. This influence is destroyed by chemical ac-
tions, and manifests itself wherever it is not sub-
dued by some antagonist 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 enter-
ing into the same state, if no cause exist in these
parts by which the change is counteracted or de-
stroyed.

Disease is excited by contagion.

The transformations produced by the disease as-
sume a series of forms.

In order to obtain a clear conception of these
transformations, we may consider the changes which
substances, more simply composed than the living
body, suffer from the influence of similar causes.
When putrefying blood or yeast in the act of trans-
formation is placed in contact with a solution of
sugar, the elements of the latter substance are trans-
posed, 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
assume a different arrangement. The sugar is con-
verted into lactic acid without the addition or loss
of any element. (1 atom of sugar of grapes C12
H12 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 differ-

400 POISONS, CONTAGIONS, MIASMS.

ent states of the transposition of the elements of the
exciting body, the elements of the sugar arrange
themselves in different manners, that is, different
products are formed.

The immediate contact of the decomposing sub-
stance 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 cessa-
tion of the decomposition 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 intro-
duced into solutions of sugar, effect the transforma-
tion of this substance, without being themselves re-
generated ; in the same manner, miasms and certain
contagious matters produce diseases in the human
organism, by communicating the state of decompo-
sition, of which they themselves are the subject, to
certain parts of the organism, without themselves
being reproduced in their peculiar form and nature
during the progress of the decomposition.

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 excites fermentation in a fresh
solution of sugar or wort. If the sugar, however,
should be first decomposed, the gluten which re-
mains in solution is not converted into yeast. We
see, therefore, that the reproduction of the exciting
body here depends, —

THEIR MODE OF ACTION. 401

1. Upon the presence of that substance from which
it was originally formed ;

2. Upon the presence of a compound w^hich is
capable 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 pro-
duced. It must further be admitted, when contagion
results, that the blood contains 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 pres-
ence of a certain quantity of this second body in the
blood of a healthy individual. The susceptibility
for the disease and its intensity must augment ac-
cording to the quantity of that body present in the
blood; and in proportion to its diminution or dis-
appearance, the course of the disease will change.

When a quantity, however small, of contagious
matter, 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 repro-
duced from wort. Its condition of transformation
will be communicated to a constituent of the blood;
and in consequence of the transformation suffered by
this substance, a body identical 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 transforma-
tion or decomposition proceeds more slowly than
that of the compound in the blood, the decompo-
sition of which it effects.

If the transformation of the yeast generated in

402 POISONS, CONTAGIONS, MIASMS.

the fermentation of wort proceeded with the same
rapidity as that of the particles of the sugar con-
tained 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 disap-
peared, there remains a much larger quantity of
yeast than existed in the fluid at the commencement
of the fermentation, — yeast which is still in a state
of incessant progressive transformation, and there-
fore possessed of its peculiar property.

The state of change or decomposition which effects
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 sub-
stances 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
childhood and youth, variable quantities of substan-
ces, which are absent from it in other stages of
growth. The susceptibility of contagion by peculiar
exciting bodies in childhood, indicates a propagation
and regeneration of the exciting bodies, in conse-
quence 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 transforma-
tions 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
malignant 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 simulta-

THEIR MODE OF ACTION. 403

neous formation of new compounds which require to
be removed from the body by the organs of excre-
tion.

In an adult these excretions do not vary much
either in their nature or quantity. The food taken
is not employed in increasing the size of the body,
but merely for the purpose of replacing any sub-
stances which may be consumed by the various
actions in the organism; every motion, every mani-
festation 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 accompanied by an abnormal condition of growth
and increase 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, diffused 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 particular parts of the body. The skin, lungs,
and other organs, assume the functions of the dis-
eased secreting organs, and the accumulated sub-
stances are eliminated by them. If, when thus
exhaled, these substances happen to be in the state
of progressive transformation, they are contagious ;
that is, they are able to produce the same state of
disease in another healthy organism, provided the
latter organism is susceptible of their action, — or
in other words, contains a matter capable of suffer-
ing the same process of decomposition.

* 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 respect
very perceptibly from that of man. — L.

404 POISONS, CONTAGIONS, MIASMS.

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 nutri-
ment taken by an individual. A superabundance of
strong and otherwise wholesome food may produce
them, as well as a deficiency of nutriment, unclean-
liness, or even the use of decayed substances as
food.

All these conditions for contagion must be con-
sidered as accidental. Their formation and accu-
mulation in the 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 over-
come the chemical action. The contagion, accord-
ingly, 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.

In the abstract chemical sense, reproduction of a
contagion depends upon the presence of two sub-
stances, one of which becomes completely decom-
posed, but communicates its own state of transform-
ation 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
accidentally present; but it may also be a matter
necessary to life. If both be constituents indispen-
sable 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 sub-
stance which was a constituent of the blood do not

THEIR MODE OF ACTION. 405

cause an immediate cessation of the functions of
the most important organs, if they continue in their
action, although in an abnormal condition, conval-
escence 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
peculiar nature are produced.

When the constituent 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
susceptibility of contagion ceases upon its disap-
pearance.

The effects of vaccine matter indicate, that an
accidental 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
Bavarian beer acts (page 350) 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
ordinary ferment are formed from gluten, just as the
vaccine virus and the matter of smallpox are pro-
duced from the blood. Ordinary yeast and the virus
of human smallpox, however, effect a violent tumul-
tuous transformation, the former in vegetable juices,
the latter in blood, in both of which fluids respec-
tively their constituents are contained, and they are
reproduced from these fluids with all their character-
istic 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 influence upon the latter substance, and
causes it to assume a new form and nature, in con-
sequence of which this kind of yeast also is repro-
duced.

The action of the virus of cow-pox is analogous
to that of the low yeast ; it communicates its own

406 POISONS, CONTAGIONS, MIASMS.

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 cow-pox.

The susceptibility of infection by the virus of
human smallpox must cease after vaccination, for
the substance to the presence of which this suscep-
tibility is owing has been removed from the body by
a peculiar process of decomposition artificially ex-
cited. 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 vaccina-
tion 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 dis-
eases of the lungs are above all others frequent and
dangerous.

If it is assumed, that chemical action and the vital
principle mutually balance each other in the blood, it
must further be supposed that the chemical powers
will 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 time by the motion of the
heart, and any change beyond a determinate point
is, in a certain degree, prevented by the rapid re-
moval 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,
animal, or inorganic bodies, act in the same way as
they do in a saturated solution of a salt in the act
of crystallization, that is, they occasion a deposition

THEIR MODE OF ACTION. * 407

of solid matters from the blood, by which the action
of the air upon the latter is altered or prevented.
""When gaseous and decomposing substances, or
those which exercise a chemical action, such as sul-
phuretted 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 decay or putrefaction, by
ammonia and alkalies^ but it is retarded by empy-
reumatic substances, volatile oils, and acids. Sulphu-
retted hydrogen produces immediate decomposition
of the blood, and sulphurous acid combines with the
substance of the tissues, the cells, and membranes.

When the process of respiration is modified by
contact 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 ani-
mal and vegetable substances, or if it acts by its
chemical properties, (not by the state in w^hich it is,)
and therefore enters into combination with parts of
the body, or causes their decomposition, it is termed
miasm.

Gaseous contagious matter is a miasm emitted
from blood, and capable of generating itself again in
blood.

But miasm properly so called, causes disease with-
out being itself reproduced.

All the observations hitherto made upon gaseous
contagious matters prove, that they also are sub-
stances in a state of decomposition. When vessels
filled with ice are placed in air impregnated with
gaseous contagious matter, their outer surfaces be-
come covered with water containing a certain quan-
tity of this matter in solution. This water soon
becomes turbid, and in common language putrefies.

408 POISONS, CONTAGIONS, MIASMS.

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, gener-
ally possess a peculiar nauseous offensive smell, a
circumstance which, in most cases, proves the pres-
ence of a body in a state of decomposition. Smell
itself may in many cases be considered as a reaction
of the nerves of smell, or as a resistance 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 accom-
panied by ammonia, which may be considered in
many cases as the means through which the con-
tagious matter receives a gaseous form, just as it is
the means of causing the smell of innumerable sub-
stances of little volatility, and of many which have
no odor. (Robiquet.)*

Ammonia is very generally produced in cases of
disease ; it is always emitted in those in which con-
tagion is generated, and is an invariable product of
the decomposition of animal matter. The presence
of ammonia in the air of chambers in which diseased
patients lie, particularly of those afflicted with a
contagious disease, may be readily detected ; for the
moisture condensed by ice in the manner just de-
scribed, produces a white precipitate 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

* Ann. de Chira. et de Phys. XV. 27.

their' MODE OF ACTION. 409

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
contagions, the ammonia is neutralized, and we thus
prevent further decomposition, and destroy the pow,-
er of the contagion, 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 prejudi-
cial 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 re-
moved from the air by alkalies ; the latter, by burn-
ing 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 phys-
iologists 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 indiff*erent substances, and
yet cannot be brought into contact with one another
in water without suffering a complete transformation.
All substances which thus suffer a mutual decompo-
sition, possess complex atoms ; they belong to the
highest order of chemical compounds. For example,
amygdalin, a constituent of bitter almonds, is a per-
fectly neutral body, of a slightly bitter taste, and
very easily soluble in water. But when it is intro-
duced into a watery solution of synaptas, (a constit-
uent of sweet almonds,) it disappears completely
without the disengagement of any gas, and the wa-

410 POISONS, CONTAGIONS, MIASMS.

ter IS found to contain free hydrocyanic acid, hydru-
ret of benzule (oil of bitter almonds), a peculiar acid
and sugar, all substances of which merely the ele-
ments existed in the amygdalin. The same decom-
position is effected when bitter almonds, which con-
Jain 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 distillation 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 amyg-
dalin, 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 distillation 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 previously to their distilla-
tion with water, the residue does not yield a volatile
oil. The alcohol contains a crystalline body called
sinapin, and several other bodies. These do not
possess the characteristic pungency of the oil, but it
is by the contact of them with water, and with the
albuminous constituents of the seeds, that the vola-
tile oil is formed.

Thus bodies regarded as absolutely indifferent in
inorganic chemistry, on account of their possessing
no prominent chemical characters, when placed in
contact with one another, mutually decompose each
other. Their constituents arrange themselves in a
peculiar manner, so as to form new combinations ; a
complex atom dividing into two or more atoms of

THEIR MODE OF ACTION. 411

less complex constitution, in consequence of a mere
disturbance in the attraction of their elements.

The white constituents of the almonds and mus-
tard which resemble coagulated albumen, must be in
a peculiar 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 being blanched and pounded, are
thrown into boiling water, or treated with hot alco-
hol, 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 dissolved in
water. Its solution becomes rapidly turbid, deposits
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 forma-
tion of the 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 gener-
al, contain a substance called diastase^ which is
formed from the gluten contained in them, and can-
not be brought in contact with starch and water,
without effecting a change in the starch.

When bruised malt is strewed upon warm starch,
made into a paste with water, the paste after a few
minutes 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 ac-
quires 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
arranged themselves into new combinations.

The conversion of the starch contained in food in-
to sugar of grapes in diabetes indicates, that amongst

412 POISONS, CONTAGIONS, MIASMS.

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 nourishment, the
chemical action may finally be subdued, or in other
words, the disease cured.

The conversion of starch into sugar may also be
effected 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
molecules, by every cause which occasions a disturb-
ance in the attraction of their elements.

When moist copper is exposed to air containing
carbonic 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 copper 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 pe-
culiar 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 temper-
ature of 388° F. (180^ C.) the intensity and direction
of the chemical force undergo a change, and the
conditions under which the elements of this com-
pound are enabled to remain in the same form cease
to be present. The elements, therefore, arrange

THEIR MODE OF ACTION. 413

themselves in a new form ; hydrocyanic acid and
water being the results of the change.

Mechanical motion, friction, or agitation, is suffi-
cient to cause a new disposition of the constituents
of fulminating silver and mercury, that is, to effect
another arrangement of their elements, in conse-
quence of which, new compounds are formed.

We know that electricity and heat possess a de-
cided influence upon the exercise of chemical affinity ;
and that the attractions of substances for one anoth-
er are subordinate to numerous causes which change
the condition of these substances, by altering the
direction of their attractions. In the same manner,
therefore, the exercise of chemical ipowers 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 an-
imals 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 principle.

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 na-
ture, only by a vis inerticB ; for a great law of nature
proves, that matter does not possess the power of
spontaneous action. A body in motion loses its mo-
tion 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 ex-
terior 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 influ-
ence of those causes. Contact with air and the most
feeble chemical action now effect changes in the com-

35*

414 POISONS, CONTAGIONS, MIASMS.

plex molecules ; even the presence of any body the
particles of which are undergoing motion or trans-
position, is often sufficient to destroy their state of
rest, and to disturb the statical equilibrium in the
attractions of their constituent elements. An imme-
diate consequence of this is, that they arrange them-
selves according to the different 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 TO PART II.

ANTIDOTE TO ARSENIC.

The following is from a letter of Samuel L. Dana, M. D.,
of Lowell, to Dr. Bartlett, published in the ** Boston Daily
Advertiser." August 3d, 1842.

** According to the experiments of M. Guibourt, white ox-
ide of arsenic, (or white arsenic) digested with hydrated
peroxide of iron, forms a compound, whose proportions
differ from that of arsenite of iron, by containing a larger
portion of'iron. It is this salt, which forms in the stomach,
when peroxide of iron is administered as an antidote to
arsenic. It contains 3| times as much iron as arsenic. It
is perfectly insoluble and innocuous. Three things are
essential to the action of this antidote.

** 1st. Perfect freedom from protoxide of iron.

**2d. Perfect freedom from free alkali, or alkali com-
bined with the oxide of iron.

**3d. It must be freshly prepared without drying.

" 1st. If the antidote contains protoxide of iron, then
that combines with the arsenic and forms a compound
which, though of sparing solubility, is yet poisonous and
prevents the ulterior good action of the peroxide of iron.
A mixture of prot and peroxides of iron is no antidote to
arsenic.

** 2d. If carbonate of potash is used to precipitate a solu-
tion of persalt of iron, a portion falls, combined with alka-
li. Hence Berzelius recommends bicarbonate of potash,
cold, to be used for this purpose. The effect of alkali,
free, or thus combined with peroxide of iron, will be, to
form soluble poisonous arsenites as above noticed.

**3d. The effect depends on the antidote being freshly-
prepared. I would therefore, in order to insure the 2d
and 3d conditions, recommend the solution of pernitrate of
iron to be taken dilute, followed by aq. am. and wet by a

416

TABLES.

little vinegar or tartaric acid, or cream of tartar ; remedies
always at hand.

**To insure perfect freedom from protoxide of iron,
I would always pass a current of chlorine, through the
solution of prepared nitrate of iron, before that is con-
sidered as fit, to be kept on hand, for the ready formation
of hydrated peroxide of iron.

TABLES:

SHOWING THE PROPORTION BETWEEN THE HESSIAN AND
ENGLISH STANDARD OF WEIGHTS AND MEASURES.

In general all the weights and measures employed in this
edition are those of the English standard. In a few cases
only, the Hessian weights and measures have been re-
tained. In these the numbers do not represent absolute
quantites, but are merely intended to denote a proportion
to other numbers. This has been done to avoid any un-
necessary intricacy in the calculations, and to present
whole numbers to the reader, without distracting his at-
tention by decimal parts. For those, however, who wish
to be acquainted with the exact English quantities, a table
is here given below.

1 lb. English is equal to 0907 19 lb. Hessian; hence,
about one-tenth less than the latter.

100

200

lb. Hessan is equal to
lbs. Hessian are equal to

1102 lb.

English.

2-204 lbs

((

3-306

4-409

5-511

6-612

7716

8-818

9-92

11 02

22-04

3306

44-09

5511

((

66-12

77-16

8818

99-29

110-2

((

220-4

TABLES.

417

300 lbs. Hessian are equal to 330-6 lbs. English.

400 .. . 440-9 **

500 ... 551-1 «

600 .. . 661-2 «

700 ... 771-6 "

800 .. . 881-8 "

900 . . . 9920 "

1000

11020

SQUARE FEET.

The Hessian acre is equal to 40,000 Hessian square
feet, or 26,911 English square feet ; 1 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.

1 Square Foot Hessian is equal to 0-673 Square Foot English.
_ - ^ jj

feet
{(

2 feet .

. 1-345

3 .

. .

2-018

. 2-691

5 .

•

• .

3-363

. 4036

7 .

•

• •

4-709

. 5-382

9 .

•

• •

6-054

. 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 cubic inch.

1 cubic foot Hessian is equal to 0-551 cubic foot English.

2 feet .

3 ...

4 . . .

5 ...

6 • ••

7 ...

8 . . .

10 . . .

1103

1-655

2-207

feet.

2-759

3-311

3-863

4415

((

4-966

((

5518

((

418

TABLES.

TABLE OF THE CORUESPONDING DEGREES ON THE SCALES OF
FAHRENHEIT, RJ^AUMUR, AND CELSIUS, OR CENTIGRADE.

SO)

•4J

O
65

212

100

149

203

140

194

131

185

122

— 4

— 5

176

113

— 8

— 10

167

104

— 12

— 15

158

— 16

— 20

— 13*

— 20

— 25

— 22

— 24

— 30

-31

— 28

— 35

— 40

— 32

— 40

— Denotes below the cipher on Fahrenheit's scale.

INDEX.

ACI

ALK

.Abnormal f meaning of the term,

140.
Absorption, by roots, 107.

Of salts, 116.
Acetone, 306.
Acid, acetic, emitted by plants, 150.

I compound atom of, 301.

transformation of, 306.

formation of, 329-334.

Apocrenic, 31.

Boracic, 122.

Carbonic, 24 - 70.

contained in the atmo-
sphere, 28.

. decomposed by plants.

43.

from respiration, 44.

from springs, 29.

— — ' why necessary to

plants, 105.
Crenic, 31.

Cyanic, transformation of, 310.
Cyan uric, 70.
Formic, 71, 86, 290.
Hippuric, 97.
Humic, 31.

properties of, 34.

Hydrocyanic, 70, 290.
Hydromellonic, 70.
Hypochlorous, 293.
Kinic, 114.
Kinovic, 301.
Lactic, 190.

production of, 321.

Meconic, 115.

Melanic, 326.

Mellitic, 363.

Nitric, source of, 88.

Oxalic, 70.

Phosphoric, in ashes of plants,

155.
Rocellic, in plants, 108.

Acii, succinic, 363.

Sulphuric, action of, on soils,
208, 248.

Tartaric, in grapes, 108.
Acids, action oi upon sugar, 303.

Arrest decay, 361.

Capacity for saturation, 108.

Organic, in plants, 27, 107.

when formed, 51.

Acre^ Hessian, 36.
Adipocire, 88.
Affinity, action of, 71.

Chemical, examples of, 292.

Weak, example of, 293.
Agave Americana, absorbs oxygen j

51.
Agriculture, in China, 193.

Object of, 100, 145, 172.

how attained, 146.

Its importance, 143.

A principle in, 187.
Air, access of, favored, 65.

Ammonia in, 29, 91.

Carbonic acid in, 41.

Effect of upon juices, 330.

on soils, 167.

Expired in phthisis, 73.

Improved by plants, 47.

Necessary to plants, 130.
Albumen, 96, contains nitrogen, 27.
Alcohol, effect of heat on, 306.

Exhaled, 72.

Products of its oxidation, 327.

From sugar, 313.
Aldehyde, 327.
Alkalies, 69, from granitic soils, 1 17.

Presence of, indicated, 215.

Promote decay of wood, 361.

Quantity in aluminous minerals,
148.
Alkaline Bases, in plants, on what
their existence depends, 1 12.

ANA

420

AZO

Alkaline Bases, salts contained in
fertile soils, 153.

Salts in plants, sources of, 151.
Allantoiuy 70.
Mloxan, 352.
Alloxantin, 352.
Alumina^ in fertile soils, 147.

Its influence on vegetation, 147,

Mistaken in ashes, 148.
Amber y origin of, 363.
Ammelin, 70.

Ammonia, 70, 86, carbonate of, from
urine, 191.

how fixed, 191.

Cause of nitrification, 338.

Changes colors, 87.

Condensed by charcoal, 104.

Conversion of, into nitric acid,
338.

Decomposition of by plants, 266.

Early existence of, 123.

Fixed by gypsum, 191.

From animals, 174.

Contained in beet-root, «&c., 93.

maple juice, 94.

stables, &c., 192,

Furnishes nitrogen, 104.

Loss from evaporation, 99.

prevented, 280.

Produced by animal organism,
123.

Product of decay, 88.

disease, 408.

Properties of, 88.

Quantity absorbed by charcoal,
104.

by decayed

wood, 104.

In rain water, 90.

How detected, 91.

Separated from soils by rain, 104.

In snow water, 91.

Solubility of, 89,

Sulphate of, 281.

Transformation of, 86.
Ammoniacal Liquor, 283.
Amylin^ its effect, 74.
Analysis of decayed wood, 359.

Of fire-damp, 372.

Of fishes, 177.

Of horse-dung, 177.

Of peat, 185.

Of guano, 201.

Of lentils, 159.

Of oak-wood, 358,

Of night-soil, 179.

Of salt water, 124,

Analysis, of soils, 217, 245.

Of wood coal, 367, 368.
Animal food, preservation of, 330.

Life, connexion of, with plants,
22.

Bodies, products of decay, 88.

complex, 302.

Animals, excrements of, 189.

Nutriment of, 22.
Annual plants, how nourished, 135.
Anthoxanthum Odoratum, acid in,

97.
Anthracite, 373.
Antidotes to Poisons, 381.
Apatite, 156.
Apotheme^ 31.
Arable Land, 146.
Aromatics, their influence on fer-
mentation, 343.
Argillaceous Earth, its origin, 147.
Arragonite, transformation of, 298.
Arrow Root, 140.
Arseniou^ Acid, action of, 381.
Artificial Manure, 199, 287.
Ashes, as manure, 182, 198.

Comparative value of, 182,

Of fir- wood, 111.

Of pine trees, 110.

Of plants, origin of salt in, 125.

Importance of examination of,
112.

Of wheat, 158.

used as a manure, 213.

Of bones, 183.

Of peat, 185.

Of coals, 198.

Phosphate of lime in, 183.
Assimilation, of carbon, 30.

Of carbonic acid, and ammonia,
131.

Of hydrogen, 80 - 84.

Of nitrogen, 85 - 105.

Its power, 140.
Atmosphere, ammonia in, 29, 92.

'Composition of, 27.

How maintained, 44.

Composition is invariable, 40.

Carbonic acid in the, 28-41.

Motion of, 46.

Oxygen in, 26.
Atoms, motions of, 297.

Permanence in position of, 297.
Attraction, powerful, overcome, 309.
Azores, glairin found there, 34,

Carbonic acid at the, 79.

Silica in hot springs of, 170.
Azote, 25.

BOT

421

CAR

Jlzotized matter in juices of plants,
137.
Substances, combustion o.f, 334.
Azulmin, 70.

Bamboo, silica in, 171.

Bark of trees, products in, 49.

Barilla, 118.

Barley^ analysis of, 155.

Barruel, his experiments on the

blood, 403.
Base, what, 69, 106.
Bases, alkaline, in plants, on what
their existence depends, 112.

Organic, 27.

Oxygen contained in, 106.

In plants, 108.

Substitution of, 109.
Beans, alkalies in, 159.

Nutritive power of, 159.
Becquerel, experiments of, 150.
Beech, ashes of, 182.
5cer, 347-357.

Bavarian, 348.

Varieties of, 347.
Beet-root sugar, 38.

Ammonia from, 93.

From sandy soils, 140.
Belgium, soils of, 241.
Benignant Disease, 402.
Benzoic acid, formed, 97.
Berzelivs, humic extract of, 34.

His analysis of bones, 158.
Birch Tree, ammonia from, 94.
Bischqff, estimate of carbonic acid,

&c , 29.
Blake, on nitrate of soda, 270.
Bleaching Salts, 141.
Blood, its office, 135.

Action of chemical agents upon,
396.

Its feeble resistance to exterior
influences, 396.

Organic salts in, 375.

Its character, 386.
Blossoms, when produced, 68.

Increased, 132.

Removal of, from potatoes, 134.
Bones, dust of, 183.

Durability of, 204.

Gelatine in, 203.

Use in composts, 212.

Composition of, 157, 158.
Bouquet of wines, 342.
Boracic Acid, 122.
Botanists, neglect of chemistry by,

Bran, use of, 185.
Brandy, from corn, 342.

Oil of, 342.
Brazil, wheat in, 153.
Bread, from wood, 133.
Brown Coal, 185.
Buckicheat, ashes of, 159.
Bulbsj how nourished, 76.

Calcareous Spar, 208.

Calcium, fluoride of, 157.

Chloride of, 192.
Calculous Disorders, 74.
Calico Printing, use of cow -dung
in, 186.

Use of phosphate of soda in, 286.

Substitute for, 186, 286.
Caoutchouc, in plants, 78.
Carbon, 24.

Afforded to the soil by plants, 76.

Assimilation of, 30 - 63.

Combination of, with oxygen, 24.

Of decaying substances seldom
affected by oxygen, 360.

Derived from air, 44.

In decaying wood, 360.

In decaying woody fibre, 361.

In sea- water, 45.

Oxide of, formed, 305.

Quantity in grain, 38.

in land, 39.

in straw, 38.

given off by man, 41.

Restored to the soil, 76.

Received by leaves, 43.

Its affinity for oxygen, 328.
Carbonate of ammonia decomposed
by gypsum, 100.

Of soda, 207.

Of lime in caverns and vaults,
128.
Carbonic acid, 70, in the atmo-
sphere, 28.

In St Michaels, 79.

Changes in leaves, 142.

Decomposed by plants, 43.

Emission of, at night, 49.

Evaporation of, 56.

Evolution from decaying bodies,
328.

From decaying plants, 84.

excrements, 99.

humus, 65.

respiration, 72.

springs, 29, 85.

woody fibre, 64.

Quantity extracted from air, 45.

CON

422

DAU

Carbonic Jlcid^ influence of light
on its decomposition, 53.

Increase of, prevented, 4'2.
Carbon of Plants j source of, 260 -

285.
Carburetted hydrogen with coal,

372.
Caverns, stalactites in, 127.
Charcoal, what, 24.

Condenses ammonia, 104.

Experiments of Lucas on, 249.

May replace humus, 78.

Theory of its action, 78.

Promotes growth of plants, 249.
Chelmsford, analysis of soil of, 246.
Chemical effects of light, 141.

Forces can replace the vital prin-
ciple, 75.

Processes in nutrition of vege-
tables, 22.

Transformations, 69, 289.
Chemistry, definition of, 21.

Organic, what is, 22.

Neglected by botanists, 55 j and
physiologists, 56.
China, its agriculture, 193.

Collection and use of manure
in, 193.
Chlorine gas, 141 ; effect of, 101.
Chloride of calcium, 192.

Of nitrogen, 293.

Of potassium, its effect, 116.

Of sodium, its volatility, 123.
Clay, burned, advantages of, as a

manure, 102.
Clays, potash in, 148.
Clay slate, 157.
Coal, formation of, 369.

Ammoniacal liquor from, 205.

Inflammable gases from, 372.

Origin of substances in, 363.

Of humus, 30, 129.

Wood or brown, 185.
Colors of flowers, 96.
Combustion at low temperatures,
327.

Of decayed wood, 362.

Induction of, 332.

Removes oxygen, 42.

Spontaneous, 324.
Compost manure, 118, 212, 279.
Concretions from horses, 156.
Constituents of plants, 24.
Consumption, 73.

Contagion, reproduction of, on
what dependent, 389.

Contagion, susceptibility to, how

occasioned, 401.
Contagions, how produced, 389.

Propagation of, 398.
Contagious matters, action of, 394,
399, 413.

Their effects explained, 390.

Life in, disproved, 392.

Reproduction of, 392.
Copper alloy, its action, on sulphu-
ric acid, 292.
Corn, how cultivated in Italy, 152

Phosphate of magnesia in, 156.

Effect of carbonic acid on, 79.
Corn brandy, 342.
Corrosive sublimate, action of, 381.
Cow, excrements of the, 120, 176,
178.

Variable in value, 179.

Urine of the, 177; rich in potash,
119.
Cow-pox, action of virus of, 405.
Crops, rotation of, 161 .

Favorable effects of, 162.

Principles regulating, 174, 275.
Cubic nitre, 270.
Cultivation, its benefits, 47.

Different methods of, 144.

Object of, 145.
Culture, art of, 126.

Of plants, principles of the, 144.
Cyanic acid, transformation of, 311.
Cyanogen, combustion of, 335.

A compound base, 70.

Transformation of, 311.
Cyanuric acid, 70.

Dana, Dr. S. L., on geine, 31.

On phosphate of lime, 182.

On ammonia, 259.

On phosphate of soda in calico
printing, 286.
Daniel's manure, 287.
Darwin, on nitrate of soda, 270.
Daubeny, experiments of, 105.

On forest trees, 164.

On nutritive qualities of plants,
265.

On source of carbon, 285.

On source of carbon of plants,
260.

On source of hydrogen of plants^
263.

Carbon of, 260.

Experiments at Oxford, 257.

Experiments on his farm, 273.

Source of hydrogen, 263.

EXC

423

FRU

Davisj his account of Chinese

manure, 193.
Death from nutritious substances,
59.

The source of life, 105.
DecandoUe, his theory of excre-
tion, 163.

Difference of his views and
those of Macaire-Princep, 167.
Decay, 292.

A source of ammonia, 88.

Of wood, 361.

Of plants restores oxygen, 84.
and putrefaction, 291.
Decomposition. 68, 289.

Organic, chemical, 291.
Dextrine, 56, 57.
Diamond J its origin, 363.
Diastase, 136.

Contains nitrogen, 136.
Disease, how excited, 386.
Dog J excrement of the, 175.
Dung hills, liquid from, 191.

Reservoirs, 191.

Substitute, 187.

Ebony wood, oxygen and hy-
drogen in, 53.
Effete matters separated, 68.
Eifet, springs evolve carbonic acid,

29.
Elements of plants, 24

Not generated by organs, 59.
Elphinstoney Sir Howard, on soda-
ash as a manure, 207.
England, analysis of soils in, 242.
Equilibrium of attractions dis-
turbed, 298.
EquisetacecB contain silica, 171.
Eremacausis, 63, 299.
Analogous to putrefaction, 328.
Arrested, 323.
Definition of, 299.
Necessary to nitrification, 335.
Of bodies containing nitrogen,

334.
Of bodies destitute of nitrogen,
329.
Ether, oenanthic, 344.
Etiolation, 46.
Eudiometer, 90.
Excrementitious matter, production

of, illustrated, 71.
Excrement, animal, its chemical
nature, 175.
Of the dog, cow, &c., 175.
Influence of, as manure, 180.

Excrements of plants, 163.

Conversion of, into humus, 35.

Of man, amount of, 195.

Value of, 189.

Preservation of, 193.
Excretion, organs of, 72.

Of plants, theory of, 163.
Experiments in physiology, object
of, 56.

Of physiologists not satisfactory.

Extract of humus, 31.

Fallow, changes from, 152.

Crops, 159.

Time, 159.
Fattening of animals, 146.
FcBces, analysis of, 179.
Ferment, 313, 314.
Fermentation, 299, 300.

Causes of, 292.

Of Bavarian beer, 348.

Of beer, 349.

Gay-Lussac's experiments in,
330.

Of sugar, 313.

Of vegetable juices, 314.

Vinous, 338.

Of wort, 3.39.
Fertility of fields, how preserved,

181.
Fires, plants on localities of, 154.
Firs, succeed oaks, 164.
Firioood, analysis of its ashes, 111.
Fishes, in salt-pans, 121.

As manure, 259
Flanders, manure in, 193.
Fleabane, 160.
Flesh, composition of, 177.

Effect of salt on, 377.
Flour, bran of, 185.
Flowers, colors due to ammonia, 96.
Fluorine, 157; in ancient bones,.

158.
Foliage, increased, 101.
Food, effect on products of plants,
139.

Of young plants, J 31.

Transformation and assimilation
of, 72.
Formation of wood, 138.
Formic add, 70, 290.

Theory of its formation, 71 .

From hydrocyanic acid, 71.
Fossil resin, origin of, 363.
Franconia, caverns in, 127.
Fruit, increased, 132.

HES

424

INO

Fruity ripening cf^ 83.

changes attending,

132.
Fulminating silver, 293.

Gaseous substances in the lungs,

effect of, 407.
Gasterosteua aculeatuSy in salt-pans,

121.
Gasworks, liquor of, 205, 283.
Gay-Lussac, his experiments, 330.
Geine, 31.

Germany, cultivation in, ]8l.
Germination of potatoes, 133.

Of grain, 137.
Glair in, 34.
Glass, as a manure, 187.

Effectof heat on,297.
Glue, manure from, 184.
Gluten, conversion of, into yeast,
348-356.

Decomposition of, 321.

Gas from, 339.
Grain, germination of, 137.

Manure for, 119.

Rust in, 220.
Chranitic, soil affords alkalies, 117.
Grapes, fermentation of, 338.

Juice of, differences in, 346.

Potash in, 112.
Grasses, seeds of, follow man, 121.

Silica in, 170.

Valued in Germany, 169.

Compost for,. 118.
Grauwacke, soil from, 147.
Growth of plants, conditions for

the, 144.
Gwano, 95, 199.

Gypsum, decomposition of, 100,
280.

Its influence, 101.

Use of, 191.

Theory of, 280.

Substitutes for, 282,

Action of, 247, 280.

Replaced, 248.

Hailstones, 91.

Hay, carbon in, 38.

Contains nitrogen, 176.

silica, 155.

Analysis of, 38.
Haystack, effect of lightning upon

a, 155.
Hesse, custom in, 213.
Hessian and English weights and
measures, 416.

Hessian acre, 36.
Hibernating animals, 134.
Hippuric acid, 97.
Horse, urine of the, 102

Concretions in the, 157.
Horse- dung, actiop of water upon,
177.

Analysis of, 178.
Human fmces, analysis of, 179.
Humate of lime, quantity received

by plants, 37.
Humic acid, 31 , 65, 90.

Action of, 129.

Properties of, 34.

Is not contained in soils, 90.

Quantity received by plants, 37.

Insolubility of, 128.
Humus, 30, 90.

Action of, 63.

Analysis of, 32.

Erroneous' opinions concerning,
49.

Extract of, 31.

Action upon oxygen, 127.

Coal of, 129.

Conversion of woody fibre into,
358

How produced, 358.

Its insolubility, 127.

Properties of, 34.

Replaced by charcoal, 78.

Source of carbonic acid, 65.

Theory of its action, 65.

Unnecessary for plants, 33, 77.
Hungary, soils of, 240.
Hydrates, 31.

Hydrocyanic acid, 70, 290.
Hydrogen, assimilation of, 80-82.

Properties of, 25.

Excess of in wood accounted
for, 81.

Of decayed wood, 359.

In plants, 263.

Of plants, source of, 82, 263.

Peroxide of, 294.
Hyett, Mr., on nitrate of soda, 206,
271.

Ice, bubbles of gas in, 54..
Indian corn, analysis of, 98.
Indifferent substances, 27.
Inflammable air, 25.
Ingenhouss, his experiments, 49.
Inorganic compounds, 301.

Action of, 374.

In what they differ from organic,
302.

MAN

425

NIT

Inorganic constituents of plants,

105, 126.
Compounds, stability of, 301.
Iodine, 126.
Iron^ oxide of, attracts ammonia,

103.
Irrigation of meadows, effect of,

127, 169.
Itch insect, 122.

Jackson^ analysis of horse-dung,
177.
On peat compost, 258.
Java^ soil of, 244 .
Juices of vegetables, 27,

Lactic acid, production of, 321.

Lava, soil from, 149.

Lead, salts of, compounds with

organic matter, 383.
Leaves, absorb carbonic acid, 43.
Ashes of, contain alkalies, 154.
Cessation of their functions, 68.
Change color from absorption of

oxygen, 68.
Consequence of the production

of their green principle, 173.
Decompose carbonic acid, 142.
Their office, 135.
Power of absorbing nutriment,

how increased, 67.
Quantity of carbon received by,

45.
Contain azotized matter, 188.
Lentils, analysis of, 159.
Life, notion of, 392.
Light, absence of, its effect, 49.
Chemical effects of, 105, 142.
Influences decomposition of car-
bonic acid, 53.
Lime, phosphate of, 183, 184, 212.
Limestone, analysis of, 153.
Lixiviation, 182.

Lucern, phosphate of lime in, 159.
Benefits attending its culture,
172.
Lucas, his experiments, 249.

MaCAIRE-PRINCEP, his experi-
ments, 164, 256.
Magnesia, phosphate of, in seeds,

62.
Maine, analysis of soil of, 246.
Mannite, 139.
Manure, 174, 208.

Animal, yields ammonia, 95, 278.
Artificial, 204, 212, 237.

36*

Manure, components of, should be
known, 144.

Carbonic acid from, 99.

Human, 284.

Of the Chinese, 193.

Effect of, 173.

Bone, 183.

Daniell's artificial, 287.
Manuring of vines, 253, 254.
Maple juice, ammonia from, 94.

Trees, sugar of, 94.
Meadoios, irrigation of, 127, 169.
Medicine, action of, remedies in,

186.
Meconic acid, 115.
Melam, 70.
Melamin, 70.
Melitic acid, 363.
Mellon, 70.
Merrimack Manuf. Co., first use of

phosphate of soda by, 286.
Metallic compounds required by

plants, 60.
Metamorphosis, 291.
Miasm, defined, 407.
Michaels, St., carbonic acid at, 79.
Minerals attract ammonia, 103.
Morbid poisons, 389.
Motion, its influence on chemical

forces, 296.
Mould, vegetable, 363.

Conversion of woody fibre into,
364.

Condenses ammonia, 104.
Mouldering of bodies, 365.
Must, fermentation of, 340.

Naples, soils of, 152, 285.
Mght-soil, 193, 199, 259, 284.
NUe, soil of its vicinity, 168.
Nitrate of soda as a manure, 206.

Theory of its formation, 277.

Of Peru, 270, 277.

Experiments with, 271.
Nitrated wheat, 272.

Flour, 275.
Nitric acid from ammonia, 336.

Animals, 88.

How formed, 335.
Nitrification, 334,

Condition for, 336.
Nitrogen from animals, 87.

Absorption of by plants, 267.

Account of, 25

Application of substances con-
taining it, 99.

Assimilation of, 85, 97.

OXY

426

PLA

J^itrogen^ chloride of, 293.

Characteristic of, 25.

Compounds of, 25, 27.

, peculiarity in,

319.

In albumen, 27.

From the atmosphere, 88.

In plants, 25, 27, 265.

Source of, 283, 285.

Production of, the object of agri-
culture, 99.

Transformation of bodies con-
taining, 305.

of bodies not

containing, 305.

In rice, 98.

In solid excrements, 189.
In urine, 189.
JVutrition, conditions essential to,
22, 59.
Inorganic substances required

in, 60.
Superfluous, how employed, 67.
Of young plants, 172.

Oaks, ashes of, 154.

Excretions of, 49.

Dwarf, 66.

Followed by firs, 164.
Oak-wood affords humic acid, 35,

Composition of, 358.

Mouldered, analysis of, 359.
Odor of substances, 345.

Of gaseous contagious matter,
408.
(Enanthic ether, 344.
Ohio, analysis of soils of, 245.
Orcin, 325.

Organs of excretion, 72.
Organic acids, 26.

Decomposition of, 295.

Chemistry, 21,22.
Compounds, 82.

Compared with inorganic salts
in plants, 301.
Organized bodies do not generate

substances, 68.
Osmazome^ 317.
Oxalic acid, 70.
Oxford, experiments at, 257.
Oxamide, decomposition of, 391.
Oxides, metallic, in fir- wood, 111 .
Oxygen, 26.

Action on alcohol, 327.

Properties of, 26.

Absorption of, at night, 51

Oxygen J absorption by respiration,
72.

leaves, 51.

plants, 49.

wood, 358.

Action upon woody fibre, 359.

Its action in decomposition, 331.

Emitted by leaves, 43.

Given to air by land, 80.

Extracted from air by mould, 364.

In air, 28.

Consumption of, 40, 41.

In water, 82.

Promotes decay, 130.

Separated during the formation
of acids, 83.

Is furnished by the decomposi-
tion of water, 81.

PaYEN, his table of composition

of woods, 264.
Peat, compost of, 118, 258.

Analysis of, 185.
Perennial plants, how nourished,

135.
Peroxide, what, 295.
Peroxide of hydrogen, 294.
Peterson and Schodler^' their analy-
sis of woods, 52.
Phosphates necessa.ry to plants, 155.
Phosphate of iron, the probable
cause of rust, 221.
In pollen, 182.
Phosphate of lime in teak wood,
156.
In forest soils, 182.
Phosphoric acid in ashes of plants,

155.
Phthisis, remedies in, 73.
Physiologists, their experiments not
satisfactory, 62.
Neglect of chemistry by, 56.
Pipe-clay, ammonia in, 103.
Plants absorb oxygen, 50.
Ashes of, salts in, 110.
Conditions necessary for their

life, 62.
Constituents of, 24.
Decay of, a source of oxygen, 84.
Decompose carbonic acid, 43.
Development of, requisites for,

27, 117, 136, 143.
Effect of, on rocks, 150.
Elements of, 24.
Emit acetic acid, 150.
Exhalation of carbonic acid
from, 53.

PRO

427

SAT

Plants, of a former world, 76.

Formation of their components,
83.

Functions of, 44.

Improve the air, 47.

Influence of gases on, 50.

■ of shade, 50.

Inorganic constituents of, 105.

Life of, connected with that of
animals, 22.

Milky-juiced, in barren soils, 78.

Nutritive qualities of, depend-
ence on nitrogen, 265.

Organic acids in, 26, 106.

salts in, 108.

Perennial, nourished, 135.

Products of, vary, 139.

Size of, proportioned to organs
of nourishment, 66.

Sources of their nourishment,
27.

Succession of, its advantage, 162.

Vital processes of, 84.

Wild, obtain nitrogen from the
air, 99.

Yield oxygen, 48.
Platinum does not decompose nitric

acid, 292.
Ploughing, its use, 130.

Recommended by Cato, 270.
Poisons generated by disease, 374.

Inorganic, 374 - 379.

Peculiar class of, 384.

Rendered inert by heat, 389.
Poisoning, superficial, 379.

By sausages, 387.
Pompeii, air from, 41.

Bones from, 158.
Potash, action of, upon mould, 364.

In limestones, 153.

In grapes, 112.

•Ley of, its effects on excre-
ments, 99.

Presence of, in plants, accounted
for, 148.

Replaced by soda, 113.

Required by plants, 62.

Quantity in soils, 148.

Silicate of, in soils, 62.

Sources of, 148.
Potatoes, oil of, 341.

Effect of, as food, 139.

Analysis of, 114.

Germination of, 133.

Produce of, increased, 134.
Poudrette, 199.
Products of transformations, 69.

Prince, J. D., first to apply phos-

phate of soda, &c., 280.
Purgative eflfect of salts explained,

377.
Pus, globules in, 397.
Pv^ey, Mr., on nitrate of soda, 206.
Putr^action, 63, 299, 300.
Of animals, 174.
Causes of, 292.
Communicated, 389.
Source of ammonia, 104.

carbonic acid, 99.

Putrefying sausages, death from,

387; their mode of action, 388.

Substances, their effect on

wounds, 389
alkaline, 397.

- acid, 397.

Radical, what, 69.

Rain-water, alkali extracted by, 150.

Reduction of oxides, 294.

Reeds and canes require silica, 155.

Removal of branches, effects of, 132.

Reservoirs of dung, 191.

Respiration, oxygen consumed by,

41.
Rhine, soils in its vicinity, 168.

Wines, 342.
Rice, analysis of, 98.
Ripening of fruit, 132.
Root secretions, 163; 256
Roots absorb, 107.

Emit excrementitious matter,
163.

Their ofliice, 125.

Secretions of, 256.
Rotation of crops, 161, 174.

Sal ammoniac, as manure, 282.

Saliculite of potash , 326.

Saline plants, 121.

Salsola kali, 113.

Salt, volatilization of, 123.

Salts, absorption of, 116.

Effect of, on the organism, 375.

on flesh, 377.

on the stomach, 377.

Organic, in plants, 27.

in the blood, 376.

Passage of through the lungs,
376.
Salt-works, loss in, 124.
SaltiDort, 122.
Sand, plants in, 78.
Sandy soil, decay of wood in, 361.
Saturation, capacity of, 106.

STA

428

TOB

Sausages, poisonous, 387.
Saussure^ his experiments on air, 42.

Analysis of pines, 110.

On the growth of plants, 158.
Schubler, his observations on rain,

90.
Sea-water, analysis of, 124.

Contains carbon, 45.

Contains ammonia, 125.
Secretions, root, 256.
Silica, 170, in grasses, 155.

Solution of, 170.

In reeds and canes, 155.
Silicate of potash in plants, 62.

As a manure, 187, 212, 213.
Siliceous sinter ^ 170.
Silver, carbonate of, action on or-
ganic acids, 295.

Salts, poisonous effects of, 382.
Simple bodies, 21.
Sinapis alba, 410.
Size of plants proportional to organs

of nourishment, 66.
Smell, what, 345.
Snow-water, ammonia in, 91.
Soda may replace potash, 113.

Nitrate of, theory of its forma-
tion, 277.

Phosphate of, in calico printing,
286.
Soda-ash, 207.

Soils, advantage of loosening, 65,
130.

Chemical constituents of, 208.

Best for meadow- land, 118.

Carbon restored to, 75.

Chemical nature of its influence,
167.

Constituents of, 208.

Exhaustion of, 151.

Ferruginous, improved, 130.

Fertile, contain phosphoric acid,
potash, &c., 242, 243.

Fertile, of Vesuvius, 149.

From lava, 149.

Of heaths, 223.

Imbibe ammonia, 99.

Improved by crops, 161.

Impoverished by crops, 161.

Various kinds of, 208.
Stagnant water, effect of, 130.
Stalactites in caverns, 127.
Starch, 56 ; composition of, 83.

Accumulation of, in plants, 132.

Development of plants influ-
enced by, 134.

Effect of, on malt, 74.

Starch, vesicles in, 56.

Product of the life of plants, 49.

In willows, 133.
Staunton, Sir G., on Chinese ma-
nure, 194.
Straw, analysis of, 38.
Struve, experiments of, 151.
Substitution of bases, 109.
Subsoil ploughing, 215, 269.
Succession of crops, 275.
Succinic acieZ, 363.
Sugar, action of alkalies upon, 303.

acids upon, 303.

Composition of, 313.

Carbon in sugar, 38.

Contained in the maple-tree, 93.

In clerodendron fragrans, &c.,
138.

Devolopment of plants, influence
on, 134.

Fermentation of, 313.

Formic acid from, 86.

In beet- roots, 93.

Metamorphosis of, 313.

Organic compounds, all form
sugar, 302.

Product of the life of plants, 49.

Transformation of, 304.

When produced, 67.
Sulphur, crystallized, dimorphous,
297.

In plants, 214.
Sulphuric Acid, action of, on soils,

208, 248.
Sulphurous Acid arrests decay, 360.
Swamp muck, 185.
Sweden, soils of, 243.
Swine, urine of, 202.
Synaptas, 411.

TABASHEER, 171.

Tables, of Hessian and English

weights, 41 6.
Tannic Acid, 83.
Tartaric Acid, 83.
Converted into sugar, 83.
In wine, 342.
Teak Tree, salts found in, 155.
Teeth, analysis of, 158.
Teltowa Parsnep, 66, 140.
Thenard, his experiments on yeast,

313.
Thermometers, scales of, 418.
Tin, action on nitric acid, 292.
Tobacco, juice contains ammonia,

94.
Leaves of, 345.

VIN

429

woo

Tobacco^ value of, proportional to
quantity of potash in tiie soil,

Nitric acid in, 97.

In Virginia, 151.
Transformation, by heat, 306.

Chemical, 71, iiiil.

Chemical transformations differ
from decompositions, 71.

Of acetic acid, 306.

Of arragonite, 298.

Of carbonic acid, 142.

Of meconic acid, 306.

Not affected by the vital princi-
ple, 74.

Explained, 74.

Of bodies containing nitrogen,
305.

Of bodies destitute of nitrogen,
305.

Results of, 75.

Of sugar, 303.

Of wood, 306.

Of cyanic acid, 311.

Of cyanogen, 311.

Of gluten, 339.
Transplantation^ effect of, 132.
Trees, diseases of, 137.

Require alkalies, 154.

ULMIN, 30.

Urea^ 70, 87 ; converted into car-
bonate of ammonia, 97.

In urine, 189.
Uric Acid, yields ammonia, 192.

Transformations of, 193.
Urinary calculi, treatment of, 74.

Organs, eliminate nitrogen, 73.
Urine J contains nitrogen, 97.

Its use as a manure, 95, 201, 211.

Of men, &c., 190.

Of horses, 202.

Human, analysis of, 190.

Of cows, 202.

Its use in China and Flanders,
95, 194.

Of swine, 202.

Vaccination, its effect, 405.

Vegetable Albumen, 9Q.

Life, one end of, 23.

Mould, 363.

Juices, fermentation of, 314.
Vesuvius, fertile soil of, 149.
Vines, new mode of manuring, 253.

Juice of, yields ammonia, 94.
Vinous Fermentation^ 338.

Virginia, early products of its soils,

151.
Virus, of small pox, 405.

Vaccine, 405.
Vitality, what, 59.
Vital Principle, 73.

Value of the term, 75.

How balanced in the blood, 374.
Vital Processes of plants, 166.
Voelckel, his analysis of guano, 96.

Water, carbonic acid of, ab-
sorbed, 44.
Composition of, 81.
Dissolves mould, 364.
Freezing of, 296.
Plants, their action upon, 56.
Rain, contains ammonia, 91.

required by plants, 28.

required by gypsum, 102.

Hard, made soft, 92.

Salt, analysis of, 124.
Wavellite, 156.
West Indies, soil of, 244.
Wheat, analysis of, 154.

Ashes of, used as a manure, 213.

Exhausts, 152.

Nitrated, 272.

Gluten of, 94.

Manure for, 213.

Why it does not thrive on cer-
tain soils, 153.

In Virginia, 151.
Wilbrand, Dr.^ on maple sugar, 93.
Willows, growth of, 133.
Wine, effect of gluten upon, 347.

Fermentation of, 347.

Properties of, 347.

Substances in, 341.

Taste and smell, 342.

Varieties of, 1342.
Wood, decomposition of, 320.
Wohler, his analysis of limestone,

153.
Wood charcoal, may replace hu-
mus, 78.

a manure, 249.

Decayed combustion of, 362.

Absorbs ammonia, 104.

Analysis of, 52.

Bread from, 133.

Composition of, 264.

Conversion of, into humus, 335.

Decay of, 357.

Requires air, 358.

Decomposition of, 320.

Elements of, 358, 360.

WOR

430

ZIN

Woody transformation of, 306.

Effect of moisture and air on,
358. ^

Formation of, 138.

Source of its carbon, 39.
Wood Coaly how produced, 365.

Analysis of, 367, 368.
Woody Fibre, changes in, 358.

Composition of, 358.

Decomposition of, 358.

Formation of, 48.

Moist, evolves carbonic acid, 358.

Mould from, 364.
Wormwood y effect of its culture,
120.

Worty fermentation of, 350.
Wounds, effect of putrefying sub-
stances on, 386.

YEASTy 315.
Destroyed, 341.
Experiments on, 316.
Formed, 340.
Its mode of action, 318.
Its production, 315.
Two kinds of, 350.

Zeine, 98.

ZinCy decomposition of water with,

84.

PROFESSOR LIEBIG'S
REPORT ON ORGANIC CHEMISTRY.

NOTICES OF PART I.
AGRICULTURAL CHEMISTRY.

This work has already acquired great reputation in Great
Britain, and several notices and reviews of it have appeared
in the foreign journals, all of which unite in expressing their
high estimation of its contents. Three lectures have been
recently delivered on Agriculture at Oxford by Dr. Daubeny,
the distinguished Professor of Chemistry and Botany, in which
he has illustrated and adopted Professor Liebig's views.

'* Every page contains a mass of information. I would
earnestly advise all practical men, and all interested in culti-
vation, to have recourse to the book itself The subject is
vastly important, and we cannot estimate how much may be
added to the produce of our fields by proceeding on correct
principles." — Loudon's Gardener^ s Magazine for March,
1841.

In alluding to this work, before the British Association for
the Advancement of Science, Dr. Gregory remarked ; —

** Every thing was simply and clearly explained. It was
the first attempt to apply the newly created science of
Organic Chemistry to Agriculture. In his opinion, from
this day might be dated a new era in the art, from the prin-
ciples established by Professor Liebig. He was of opinion,
that the British Association had just reason to be proud of
such a work, as originating in their recommendation."

The followins: is from the address at the Anniversary
Meeting of the Royal Society, November 30, 1840, when
one of the Copley medals was awarded to Professor Liebig,
in presenting which, the President, the Marquis of Northamp-
ton, thus addressed Professor Daniell, who, in the absence
of Professor Liebig, received for him the medal; —

*' 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. Liebig'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."

*' It is the best book," writes Mr. Nuttall, **ever pub-
lished on Vegetable Chemistry as applied' to Agriculture,
and calculated undoubtedly to produce a new era in the

science."

Extract from a letter from Mr. Colman, Commissioner for
the Agricultural Survey of Massachusetts, dated February
15th, 1841; —

*'It is the most valuable contribution to Agricultural sci-
ence, which has come within my knowledge. It takes new
views on many subjects, which have been long discussed
without any progress towards determinate conclusions ; and
reveals principles, which are of the highest importance.
Some of these principles require further elucidation and
proof; but, in general, they are so well established by facts
within my own observation, that in my opinion the truth, if
not already reached, is not far distant."

From Silliman's Journal, January, 1841 ; —

''It is not too much to say, that the publication of Profes-
sor Liebig's Organic Chemistry of Agriculture, constitutes
an era of great importance in the history of Agricultural
science. Its acceptance as a standard is unavoidable, for , fol-
lowing closely in the straight path of inductive philosophy, the
conclusions which are drawn from its data are incontrovertible,"
— ''To some, the style of this work may seem somewhat
obscure ; but it will be found, on a re-perusal, that great
condensation, brevity, and terseness, have been mistaken
for obscurity." — "We can truly say, that we have never
risen from the perusal of a book with a more thorough con-
viction of the profound knowledge, extensive reading, and
practical research of its author, and of the invincible power
and importance of its reasonings and conclusions, than we
have gained from the present volume."

In the notice from which the foregoing is extracted, the
learned editors enumerate among the most important chap-
ters, those on manure, the composition of animal manure,
the essential elements of manure, bone manure, the supply
of nitrogen by animal matter, mode of applying urine, value
of human excrements, &;c.

The Second Part of the work is a masterpiece of con-
densed reasoning on chemical transformations, fermentation,
decay, and putrefaction, and on contagion, poisons, and
miasms.

From the Farmer's Register, Petersburg, Va., August,
1841 ; —

** This work of Professor Liebig has received more re-
spectful attention and applause, than any on Agriculture that
has issued from the press." — **No work have we yet seen
that furnished to Agriculturists a more abundant store of
scientific facts." — ** We earnestly recommend to scientific
Agriculturists and to Chemists to study Liebig."

'*By the perusal of such works as this, the farmer need no
longer be groping in the dark, and liable to mistakes ; nor
would the not unnatural odium of farming by the book, be
longer existent.

** In conclusion, we recommend the work to the Agricul-
turist and to the Horticulturist, to the amateur florist, and to
the curious student into the mysteries of organic life, — as-
sured that they will find matter of interest and of profit in
their several tastes and pursuits." — Hovey's Magazine of
Horticulture y &c., September, 1841.

'' We regard the work of Liebig as a work of extraordinary
philosophical acumen, and conferring upon him the highest
honor. The more it is examined, the deeper will be the inter-
est which it will create, and the stronger the admiration of the
ability with which it is written. It is not a work to be read,
but studied ; and if further inquiries and experiments should
demonstrate, as seems to us from many facts within our own
knowledge in the highest degree probable, the soundness of
his views, his work, not merely as a matter of the most inter-
esting philosophical inquiry, but of the highest practical utili-
ty, will be invaluable." — JVbW/i American Review, July, 1841.

*' Dr. Webster has rendered an important service to the agricul-
tural community, by presentinsr an edition of this now well known
and highly esteemed work. Professor Liebig has for some time
been known as one of the most eminent chemists of Europe, and the
publication of this work in England has excited general and unqual-
ified approbation. Almost all the scientific and literary periodicals
have been loud in its praise, and all concur in the opinion, that a
new era in agriculture must date from its appearance. The present
edition has been greatly increased in value and utility by the addi-
tions which it has received from the American editor. The Notes
and Appendix contain much important information for the agricul-
turist, and the explanations which have been added of chemical
terms, render it intelligible to all. It should be in the hands of every
farmer. The typography and general appearance of the volume is
such as might be expected from the University Press." — Christian
Examiner, July, 184 J.

*' In the present work, Dr. L. has pointed out the path to
be pursued, and has amply vindicated the claim of science to
be considered the best guide, by correcting the erroneous
views hitherto prevailing, of the sources whence plants derive
their nourishment, by developing the true causes of fertility
in soils, and finally, by establishing, on a firm basis, the true
doctrine of manures." — Quarterly Revieiu, March, 1842.

NOTICE OF PART II.
ANIMAL CHEMISTRY.

" While we have given but a very imperfect sketch of this origi-
nal and profound work, we have endeavored to convey to the read-
er some notion of the rich store of interesting matter which it con-
tains. The chemist, the physiologist, the medical man, and the
agriculturist, will all find in this volume many new ideas and many
useful practical remarks. It is the first specimen of what modern
organic chemistry is capable of doing for physiology; and we have
no doubt that, from its appearance, physiology will date a new era
in her advance. We have reason to know that the work, when in
progress, at all events the more important parts of it, were submit-
ted to Mailer of Berlin, Tiedemann of Heidelberg, and Wagner of
Gottingen, the most distinguished physiologists of Germany ; and
without inferring that these gentlemen are in any way pledged to
the author's opinions, we may confidently state that there is but one
feeling among them as to the vast importance of Chemistry to Phys-
iology at the present period ; and that they are much gratified to
see the subject in such able hands." — Quarterly Revieiv,

THE

HISTORY OF HARVARD UNIVERSITY.

By JOSIAH QUINCY, LL. D.,

PRESIDENT OF THE UNIVERSITY.

CAMBRIDGE :
PUBLISHED BY JOHN OWEN.

[Rojal 8vo. Vols. I. and II. pp. 612 and 728.]
21 Engravings.

'' This History is a monument of patient and unwearied
investigation, — of rigid impartiality and discrimination in
deductions from time-worn records. It embraces the events
of two centuries, and historical and biographical notices of
nearly every individual whose name is found connected with
any important incident in the annals of the University." —
Boston Courier,

''There is no hazard in saying, that this work is rich in
materials, many of which have escaped the notice of even
extensive readers, and that it bears marks of thorough re-
search, and great care in the collection and verification of
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opement of the narrative." — Daily Advertiser.

'•The American press has rarely, if ever before, sent
forth two such beautiful volumes in typographical execution,
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the venerable University of Cambridge. To the numerous
Alumni of Harvard, these volumes will be precious indeed."
— JVeio York American.

" The history of the University is now written ; and it
needs no prophetic sagacity or boldness to assert, that it will

endure. For the indefatigable diligence and learned re-
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the fullness, candor, and impartiality, with which they are
now exhibited ; for the light reflected thus on the history,
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in the successive periods of its history, to the gratitude and
veneration of her sons in all coming time,. — we ofl?er him,
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dial thanks.*' — Christian Examiner,

** We expected to find in these volumes the authentic re-
sults of diligent research, and accordingly, a valuable con-
tribution to the completeness of existing aids to an acquaint-
ance with the men and doings of the ancient times. But we
confess we did not expect to find them so fruitful in enter-
tainment, and in materials for engaging and profitable, as
well as (to a patriot) complacent reflection. We did not
expect to see a record of the fortunes of a single institution
of learning, taking the place, which this seems to us des-
tined to take, among works of historical literature.

**This is not a book to be welcomed and enjoyed by the
friends of Harvard College alone, nor by either of the small
classes of New England, or of academical antiquaries, but
one which will sustain permanent claims on the attention of
the general student of history." — JYorth American Review.

This work is, in fact, not simply the history of one of our
most ancient literary institutions, but a history of the prog-
ress of letters in New England from the earliest days of the
Puritan colonists ; the history of the most illustrious minds,
for heroism and genius, which have adorned the annals of
Massachusetts for the last two centuries.

The whole net proceeds of the sale of these volumes will
be devoted to assist indigent students.

WORKS RECENTLY PUBLISHED BY

J. OWEN, CAMBRIDGE.

THE HISTORY OF HARVARD UNIVERSITY, by Josiah
QuiNCY, LL. D., President of the University. With 21 Engrav-
ings. 2 vols, royal 8vo. cloth.

VOICES OF THE NIGHT, by Henry Wadsworth Long-
fellow. 6th edition. 16mo. boards.

THE SAME, royal 8vo. fine paper, boards.

THE CLOUDS OF ARISTOPHANES. With Notes by C. C.
Felton, Professor of Greek Literature in Harvard University.
12mo. cloth. /

LECTURES ON MODERN HISTORY, from the Irruption of
the Northern Nations to the close of the American Revolution.
By William Smyth, Professor of Modern History in the Univer-
sity of Cambridge. From the Second London Edition, with a
Preface, List of Books on American History, &c., by Jared
Sparks, LL. D., Professor of Ancient and Modern History in
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BALLADS AND OTHER POEMS, by Henry Wadsworth
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THE SAME, royal 8vo. fine paper, boards.

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AN INQUIRY into the Foundation, Evidences, and Truths of
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PROF. LIEBIG'S REPORT ON ORGANIC CHEMISTRY.

PART I.

AGRICULTURAL CHEMISTRY.

CHEMISTRY in its Application to Agriculture and Physiology.
By Justus Liebig, M. D., Ph. D., F. R. S., M. R. L A., Professor of
Chemistry in the University of Giessen, &c. Edited from the
Manuscript of the Author, by Lyon Playfair, Ph. D. With
numerous Additions, and a New Chapter on Soils. Third Ameri-
can from the Second English Edition, with Notes and Appendix,
by John W. Webster, M. D., Erving Professor of Chemistry in
Harvard University. 12mo.

PART II.

ANIMAL CHEMISTRY.

ANIMAL CHEMISTRY, or Organic Chemistry in its Application
to Physiology and Pathology. By Justus Liebig, M. D., Ph. D.,
F. R. S., M. R. I. A., Professor of Chemistry in the University of
Giessen, &c. Edited from the Author's Mfinuscript, by William
Gregory, M. D., F.R. S. E., M. R. L A., Professor of Medicine
and Chemistry in the University and King's College, Aberdeen.
With Additions, Notes, and Corrections, by Dr. Gregory, and
others by John W. Webster, M.D., Erving Professor of Chem-
istry in Harvard University. 1 vol. 12mo.

IN PRESS,

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UNIVERSITY OF CAUFORNIA I^JBRARY

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Full text of "Chemistry in its application to agriculture and physiology"

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