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CHEMISTRY

IN ITS APPLICATIONS

AGRICULTURE AND PHYSIOLOGY.

BY

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

PROFKSSOR OK CHEMISTRY IN THE UNIVERSITY OF GIKSSEN, ETC., ETC

EDITED FROM THE MANUSCRIPT OF THE AUTHOR,

BY LYOX PLAYFAIR, Ph.D., F.G.S.,

HONORARY MEMBER OF AND CONSULTING CHEMIST TO THE ROYAL AORICULTCRAL
SOCIETY OF ENGLAND,

AND WILLIAM GREGORY, M.D., F.R.S.E.,

rROFCSSOR OF CHEMISTRY IN THE UNIVERSITY OF EDINBUROB.
' ' ... . » • » •

FROM TUt FOUfe^^lI LONDON EDITION,

REVISED AND ENLARGED.

NEW YORK:
JOHN WILEY, 167 BROADWAY.

1852.

\

€"

MAIN LIBRARY AGRIC. DEFr.

C . * • ,« c

ADVERTISEMENT
TO THE FOURTH EDITION.

The present edition is enriched with a large number of recent
analyses of manures ; and especially of the ashes of plants,
which will be found in the Appendix to Part I. The greater
number of these analyses have been made under the eye of the
Author in the Laboratory at Giessen, and with the aid of the
most improved methods.

At the request of Professor Liebig I assisted in the preparation
of the last edition of this Work, the various engagements of Dr.
Play fair having so fully occupied his time as to preclude him
from giving the requisite attention to it. The same causes have
led to my undertaking the entire revision of the present edition.

WILLIAM GREGORY.
Umitbrsity or EoiNBrReH,
March, 1847.

|yi66978

AUTHOR'S PREFACE
TO THE THIRD EDITION.

Majvy views and principles which I had endeavored to de. 'elope
in reference to nutrition, and especially to the cultivation of
vegetables, were strongly opposed, immediately on the appeaV-
ance of the first edition of this Work. I could not, however,
resolve to make any material change in the immediately succeed-
ing edition, because I did not consider the scientific investigation
of the important questions at issue as completed, and because I
thought that I ought to trust the decision of them to experience
alone.

Many of the objections raised were founded upon a want of
mutual understanding ; others related to positions and assertions
having no connexion with the peculiar object of the book. I
have set these aside by the omission of all passages thus called
in question.

In the three years which have elapsed between this edition and
the first, I have not neglected any opportunity of subjecting to a
rigorous and careful examination the principles which I had
developed of the nutritive properties of plants, and their applica-
tion to agriculture. I have endeavored to make myself acquainted
with the condition of practical farming, and with what it requires,
by a journey through the agricultural districts of England and
Scotland ; and during this interval a long series of experiments

riii PREFACE.

were carried on in the Laboratory of this place, with the sole
object of giving a firmer basis to my exposition of the causes of
the advantageous results attending the practice of rotation of
crops, and also of effectually banishing all doubts concerning
their accuracy.

In my "Chemistry in its applications to Physiology and
Pathology," I have subjected the process of nutrition of the
animal organism to a stricter investigation ; and I am now, for
the first lime since the completion of these labors, in a situation
to give a simple and determinate expression to my view of the
origin of animal excrements, and of the cause of their beneficial
effects on the growth of all vegetables.

Now that the conditions which render the soil productive and
capable of affording support to plants, are ascertained, it cannot
well be denied that from Chemistry done further progress in
Agriculture is to be expected.

Every unprejudiced person will, I trust, be finally convinced
by this third edition, that I have earnestly endeavored to perfect
my views, and have striven, with the best intentions, to ascertaiii
truth and obviate error.

JUSTUS LIEBIG.

GlESSKN,

JlMfutl, 1843.

J )u «ia«4«Hli 4|*«i*« 4>' i*^';^ ..■'i-^iik, kHi^.

THE BRITISH ASSOCIATIOJI

ADVANCEMENT OF SCIENCE.

One of the most remarkable features of modern times is the
combination of large numbers of individuals representing the
whole intelligence of nations, for the express purpose of ad-
vancing science by their united efforts, of learning its progress,
and of communicating new discoveries. The formation of such
associations, 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 acknowledgment of these benefits, and this acknowledgment
proceeding from whole nations may be considered the triumph of
mind over empiricism.

Innumerable are the aids afforded to the means of life, to
manufactures, and to commerce, by the truths 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

DEDICATION.

mental culture is most beneficial ; and the new views acquired
by the knowledge of them enable the mind to recognise, 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 the Association
with a part of this report.

I have endeavored to develope, in a manner correspondent to
the present state of science, the fundamental principles of
Chemistry in general, and the laws of Organic Chemistry in
particular, in their applications to Agriculture and Physiology ;
to the causes of fermentation, decay, and putrefaction ; to the'
vinous and acetous fermentations, and to nitrification. The con-
version 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 attention 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 industry — 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 actions of
manure upon them. This knowledge we must seek from Che-
mistry, which teaches the modo of investigating the composition
and of studying the characters of the different 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 transformations and changes

DEDICATION.

in the living body are exclusively dependent on their influence.
The diseases incident to the period of growth of man, contagion,
and contagious matters, have their analogues in many chemical
processes. The investigation of the chemical connexion subsist-
ing between those actions proceeding 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
co-operation of physiologists. Hence I have merely brought
forward the purely chemical part of the inquiry, and hope tc
attract attention to the subject.

Since the time of the immortal author of the " Agricultural
Chemistry," no chemist has occupied himself in studying the
applications of chemical principles to the growth of vegetables,
and to organic processes. 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 assistance which has been afforded
me in its preparation by that intelligent young chemist during his
residence in Giessen. I cannot suppress the wish that he may
succeed in being as useful, by his profound and well-grounded
knowledge of chemistry, as his talents promise.

JUSTUS LIEBIO.

Giessen,
September 1, 1840.

CONTENTS.

rios

Ojiject or THE Work ..-.----. 1

PART THE FIRST.

ON THE CHEMICAL PROCESSES IX THE NUTRITION OF VEGE'IABLIM.

CHAPTER

I. — The Constituent Elements of Plants 3

II. — The Origin and Assiniilntion of Carbon . - - - 5

III. — On the Origin and Action of Hunuis ----- 28

IV.^ — On the Assimilation of Hydrogen 35

V. — On the Origin and Assimilation of Nitrogen - - - 40

Vr.— On the Source of Sulphur 58

VII. — Of the Inorganic Constituents of Plants - - - - 64

VIII. — On the Formation of Arable Land ----- 81

IX.— The Art of Culture 93

X.— rOn Fallow . . 103

XI.— On the Rotation of Crops 133

XII. — On Manure - - 16G

XIII.— Retrospective view of the Preceding Theories - - - 186

Supplementary Chapters. — The Sources of Ammonia - - 205

Is Nitric Acid food for plants ? 214

Does the Nitrogen of the Air take part in Vegetation ? - 223

Giant Sea-weed -------- 225

Appendix to Part I. - 227

Experiments of Wiegmann and Polstorf - - - 227

and Analyses of Boussingault ... 231

Analyses of Hertwig - - 238

Fresenius ----.-. 239

Berthier 240

De Saussure ------ 242

Recent Analyses of the Ashes of Plants - - . 247, 254

Analyses of Animal Excrements ----- 255

Urine ---.-.-. 256

Guano - - - - - . - 258

Marl - 264

Ammonia in the Soil 264

CONTENTS.

PART THE SECOND.

ON THE CHEMICAL PROCESSES OP FERMENTATION, DECAY, AND
PUTREFACTION.

CHAPTER PA.OI

I. — Chemical Transformations - 265

II. — On the Causes which effect Fermentation, Decuy, and Putre-
faction 26S

III. — Fermentation and Putrefaction ------ 27ij

IV, — On the Transformation of Bodies which do not contain Nitro-
gen as a Constituent, and of those in which it is present - 280
On the Transformation of Bodies containinj^ Nitroj^en - 2S2

V. — Fermentation of Sugar - - 287

Yeast or Ferment --- 289

VI. — Eremacausis, or Decay - - 295

VII. — Eremacausis, or Decay of Bodies destitute of Nitrogen :

Formation of Acetic Acid ------ 302

VIII. — Eremacausis of Substances containing Nitroge'n. — Nitrifi-
cation ---------- 307

IX. — On Vinous Fermentation : — Wine and Beer - - - 311
X. — On Fermentation ascribed to the Growth of Fungi and of

Infusoria 328

XL— Decay of Woody Fibre - - 338

XII.— Vegetable Mould 344

XIII.— On the Mouldering of Bodies : — Paper, Brown Coal, and Mine-
ral Coal 340

XIV. — On Poisons, Contagions, and Miastis 354

Appendix to Part II. 391

Index 393

ORGANIC CHEMISTRY

IN ITS APPLICATION TO

VEGETABLE PHYSIOLOGY AND AGRICULTURE.

The 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 which 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 nutrition of their frame. An inquiry, therefore, into the
conditions on which the life and growth of living beings depend,
involves the study of those nutritive substances, as well as the
investigation of the sources whence they are derived, and of the
changes undergone by them in the process of assimilation.

A beautiful connexion subsists between the organic and inor-
ganic kingdoms of nature. Inorganic matter affords food to
plants; ; and they, on the other hand, yield the means of subsist-
ence to animals. The conditions necessaiy for animal and vege-
table nutrition arc essentially different. An animal requires for
its development, and for the sustenance of its vital functions, a
certain class of substances which can be generated only by
organic beings possessed 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 vegetable matter. Plants, on the other

PART I. 2

SUBJECT OF THE WORK

hand, 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 purport of this
work is, to elucidate the chemical processes engaged in the
nutrition of vegetables, as well as the changjes which they undergo
after death.

The first part of it will be devoted to the examination of the
matters which supply the nutriment of plants, and of the changes
which these matters undergo in the living organism. The che-
mical compounds which aiford to plants their principal constitu-
ents, viz., carbon, nitrogen, hydrogen, oxygen, and sulphur, 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 peculiar processes
usually described as fermentation, putrefaction, and decay. By
the action of these processes, the complete destruction of plants
and animals after death is effected. Flence the changes under-
gone by the elements of organic tissues in their conversion into
inorganic compounds, as well as the cause by which these changes
are determined, will become matter of inquiry.

PART I.

THE CHEMICAL PROCESSES IN THE NUTRITION OP
VEGETABLES.

CHAPTER I.

The Constituent Elements of Plants.

Carbon and hydrogen invariably occur in all parts of plants.
They form constituents of all their organs, and are essential to
their existence. v

The substances which constitute the principal mass of every
vegetable are compounds of carbon with oxygen and hydrogen,
in the proper relative proportions 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 producing water by union with the hydro-
gen. The numerous organic acids met with in plants, belong,
with few exceptions, to this class.

A third class of vegetable compounds contains carbon and hy-
drogen, but no oxygen, or less of that element than would be
required to convert all the hydrogen into water. These may be
regarded as compounds of carbon with the elements of water, and
an excess of hydrogen. Such are the volatile and fixed oils,
wax, and the resins. Many of them have acid characters.

The juices of all vegetables contain organic acids, generally
combined with the inorganic bases, or metallic oxides ; for metal-
lic oxides exist in every plant, and may be detected in its ashes
after incineration.

THE CONSTITUENT ELEMENTS Ox^ PLANTS.

Nitrogen is found in plants in the form of vegetable albumen
and gluten ; it is also a constituent of some of the acids, and of
what are termed the " indifferent substances " of plants, as well
as of those peculiar vegetable compounds called " organic
bases," which possess all the properties of metallic oxides. The
seeds also of all plants contain nitrogenous compounds.

Estimated by its proportional weight, nitrogen forms only a

small part of plants ; but it is never entirely absent from any

•pjiKtof theip..' iljv^ni \\hen it does not absolutely enter into the

c€)rt>positi(5n "bf a' jiarticular part or organ, it is always to be found

ill the "fluids -v/l^ich p.t\rv'ade it.

'* •'jCh6 ''niti-ogehcyU-i^ com[Jounds thus invariably present in the
seeds and juices of plants contain a certain quantity of sulphur.
When the juices, seeds, or organs of particular kinds of plants
are subjected to distillation along with water, peculiar oily sub-
stances pass over. These are volatile, and are characterized by
their large proportion, both of sulphur and of nitrogen. The
volatile oils of the horse-radish and of mustard are examples of
this class of bodies.

From the remarks now made, it is obvious that there are two
great classes into which all vegetable products may be arranged.
The first of these contains nitrogen ; in the last this element is
absent. The compounds destitute of nitrogen may be divided
into those in which oxygen forms a constituent (starch, lignine,
<&c.), and those into which it does not enter (oils of turpentine
and lemon, &c.). The nitrogenous compounds may, in like
manner, be divided into three smaller classes. The first of these
is distinguished by containing both sulphur and oxygen (in all
seeds) ; the second contains sulphur, but is devoid of oxygen (as
oil of mustard) ; while the third is composed of bodies from
which sulphur is entirely absent (organic bases).

It follows from the facts thus far detailed, that the development
of a plant requires the presence, first, of substances containing
carbon, nitrogen, and sulphur, and capable of yielding these
elements to the growing organism ; secondly, of water and its
elements ; and lastly, of a soil to furnish the inorganic matters
which are likewise essential to vegetable life.

PROPERTIES OF HUMUS.

CHAPTER II.
THE ORIGIN AND ASSIMILATION OF CARBON.

Composition of Humus.

Some virgin soils, such as those of America, contain vegetable
matter in large proportion ; and as these have been found emi-
nently adapted for the cultivation of most plants, the organic
matter contained 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 sub-
stance appears to play such an important part in the phenomena
of vegetation, that vej^etable 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 a product of the putrefaction and decay of vegetable matter.

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 ex-
ternal characters and chemical properties which it presents.
Thus, ulmin, humic acid, coal of humus, and humin, are names

* When the weight of the soluble parts of this vegetable matter is com-
pared with that of the plants growing upon t, it is seen that only a very
small part of their substance could have been procured through its agency.
This is the case even in the most fertile soils. — (Saussure, Richerehe*
$ur la VigHation.

OF THE ASSIMILATION OF CARBON.

applied to modifications of humus. They are obtained by treat-
ing peat, woody fibre, soot, or brown coal, with alkalies ; by de-
composing 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 sup-
posed that their composition is identical. But a more erroneous
notion could not be entertained ; since even sugar, acetic acid,
and resin, do not differ more widely in the proportions of their
constituent elements, than do the various modifications of humus.

HuMic ACID formed by the action of hydrate of potash upon
sawdust contains, according to the accurate analysis of Peligot,
72 per cent, of carbon, while the humic acid obtained from turf
and brown coal contains, according to Sprengel, only 58 per
cent. ; that produced by the action of dilute sulphuric acid upon
sugar, 57 per cent, according to Malaguti ; and that, lastly,
which is obtained from sugar or from starch, by means of muri-
atic acid, according to the analysis of Stein, 64 per cent. Mala-
guti states, moreover, that humic acid contains an equal number
of equivalents of oxygen and hydrogen, that is to say, that these
elements exist in it in the proportions for forming water ; while,
according to Sprengel, the oxygen is in excess ; and Peligot esti-
mates the quantity of hydrogen at 14 equivalents, and the oxygen
at only 6 equivalents, making the deficiency of oxygen as great
as 8 equivalents. Mulder and Herrmann have shown that de-
cayed willow- wood, peat, or vegetable mould, after being treat-
ed with water and alcohol, leave a solid brown substance, which
yields to alkalies a peculiar humic acid. This humic acid con-
sists of carbon and the elements of water. But besides these
usual constituents, it contains a certain quantity of ammonia, in
a state of chemical combination.

It is quite evident, therefore, that chemists have been in the
habit of designating by the names of humic acid or humin, all
the brown or black-colored products of the decomposition of
organic bodies, according as they were soluble or insoluble in

PROPERTIES OF HUMUS.

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 decomposition 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 influence on
the growth of plants, either in the way of nourishment or other-
wise.

Vegetable physiologists have, without any apparent reason, im-
puted the known properties of the humus and humic acids of che-
mists to that constituent of mould which has received the same
name, and in this way have been led to their theoretical notions
respecting the functions of the latter substance in vegetation.

The opinion that the substance called humus is extracted from
the soil by the roots of plants, and that the carbon entering into
its composition serves to nourish their tissues, without previously
assuming another form, is considered by many as so firmly estab-
lished that any evidence 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 examination, is
found to be untenable, and it becomes evident from most con-
clusive 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 hitherto ren-
dered it impossible to ascertain the true theory of the nutritive
process in vegetables, and has thus deprived us of our best guide
to a rational practice in agriculture. Any great improvement
in that most important of all arts is inconceivable, without a
deeper and more perfect acquaintance with the substances which
nourish plants, aod with the sources whence they are derived ;
and no other cause can be discovered to account for the fluctuat-

* This remark applies more to German than to English botanists and
physiologists. In England, the idea that humus, as such, affords nourish-
ment to plants is by no means general ; but on the Continent, the viewi
of Ber^elius on this subject have been almost universally adopted. — ^Ed.

OF THE ASSIMILATION OF CARBON.

ing 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 iruMus of vege-
table physiologists to be really endowed with the properties
recognised by chemists in the brownish-black deposits obtained
by precipitating 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 v/ater, and combines with
alkalies, forming with lime and magnesia compounds of the same
degree of solubility (Sprengel).

Vegetable physiologists agree in the supposition that by the
aid of water humus is rendered capable of being absorbed by the
roots of plants. But according to the observation of chemists,
humic acid is soluble only when newly precipitated, and becomes
completely insoluble when dried in the air, or when exposed in
the moist state to the freezing temperature (Sprengel).

Both tlie 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 f-f good mould with cold water. The fluid
remains colorless, and is found to have dissolved less than
To~dV"6T P^^"t o^' 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 prin-
cipal constituent, was found by Berzelius to yield to cold water
only slight traces of soluble materials ; and I have myself veri-
fied this observation on the decayed wood of beech and fir.

These facts, which show that humic acid, in its insoluble con-
dition, cannot serve for the nourishment of plants, have not
escaped the notice of physiologists ; and hence they have
assumed that the lime or the different alkalies found in the ashes
of vegetables, render soluble the humic acid, and fit it for the
process of assimilation.

Alkalies and alkaline earths do exist in the different kinds of

ABSORPTION OF HUMUS.

{oil, in sufficient quantity to form such soluble compounds with
lumic acid.

Now, let us suppose that humic acid is absorbed by plants in

khe form of that salt which contains the largest proportion of

lumic acid, namely, in the form of humate of lime ; and then,

from the known quantity of the alkaline bases contained in the

ishes 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 and manganese have the

5ame capacity of saturation as lime with respect to humic acid,

md then we may take as the basis of our calculation the analysis

if M. Berthier, who found that 1000 lbs. of dry fir- wood yielded

^•3 lbs. of ashes, and that in every 100 lbs. of these ashes,

educting the chloride of potassium, the silicate, and sulphate

f potash, 46-1 lbs. consisted of the basic metallic oxides, potash,

coda, lime, magnesia, iron, and manganese.

One Hessian acre* of woodland yields annually, according to
J >r. Heyer, on an average, 2650 lbs. of dry fir-wood, which con-
' lins 10-07 lbs. of metallic oxides.

Now, according to the estimates of Malaguti and Sprengel, 1
I J. of lime combines chemically with 10*9 lbs. of humic acid ,'
1 0*07 lbs. of the metallic oxides would accordingly introduce
i.ito the trees nearly 111 lbs. of humic acid, which, admitting
humic acid to contain 58 per cent, of carbon, would correspond
to 165 lbs. of dry wood. But we have seen that 2650 lbs. of
fir-wood are really produced.

Again, if the quantity of humic acid which might be intro-
duced 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
one Hessian acre would receive in that way 57^ lbs. of humic
acid, corresponding to 85 lbs. of woody fibre. But the extent
of land just mentioned produces, independently of the roots and
grain, 1780 lbs. of straw, the composition of which is the same
as that of woody fibre.

• One Hessian acre is equal to 40,000 square feet, Hessian, or 26,910
square feet, English measure.
PART TI. 2*

10 or THE ASSIMILATION OF CARBON.

It has been taken for granted in these calculations, that the
basic metallic oxides which have served to introduce humic acid
into the plants do not return to the soil, since it is certain that
they remain fixed in the parts newly formed during the process
of growth.

Let us now calculate the quantity of humic acid which plants
can receive under the most favorable circumstances, viz., through
the agency of rain-water.

ThB quantity of rain which falls at Erfurt, one of the most
fertile districts of Germany, during the months of April, May,
June, and July, is stated by Schubler to be 17^ lbs. over every
Hessian square foot of surface (=0*672 square foot English) :
one Hessian acre, or 26,910 square feet, consequently receive,
in round numbers, 700.000 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 fotir
months after it is planted, so that not a pound of 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 generally diffused of the humates, and that which con-
tains the largest proportion of humic acid) ; then the plants thus
nourished Would not receive more than 350 lbs. of humic acid,
since one part of humate of lime requires 2000 parts of water
for solution.

But the extent of land which we have mentioned produces
2580 lbs. of corn (in grain and straw, the roots not included),
or 20,000 lbs. of beet-root (without the leaves and small fibres
of the radicle). It is quite evident that the 350 lbs. of humic
acid, supposed to be absorbed, cannot account even for the
quantity of carbon contained in the fibres of the radicle 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 ihe rain-water which falls
upon the surface of the earth is absorbed by plants and evapo-
rates through their leaves, the quantity of carbon which can be
conveyed into them in any conceivable manner, by means of
humic acid, must be almost inappreciable, in comoarison with
that actually produced in vegetation.

ABSORPTION OF HUMUS. II

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 re-
markable degree.

2650 lbs. of lirs, pines, beeches, &c., grow annually as wood
upon one Hessian acre of forest-land with an average soil. The
same superficies yields 2500 lbs. of hay.

A similar surface of corn-land gives from 18,000 to 20,000
lbs. of beet- root ; or 800 lbs. of rye, and 1780 lbs. of straw, — in
all 2580 lbs.

One hundred parts of dry fir- wood contain 38 parts of carbon ;
therefore, 2650 lbs. contain 1007 lbs. of carbon.

One hundred "parts of hay,* dried in air, contain 40*73 parts
carbon. Accordingly, 2500 lbs. of hay contain 1018 lbs. of
carbon.

Beet-roots contain from 89 to 89-5 parts water, and from 10-5
to 11 parts solid matter, which contains 40 per cent, of carbon.f

20,000 lbs. of beet-root contain, therefore, 880 lbs. of carbon,
the quantity of this element in the leaves and small roots not
being included in the calculation.

One hundred parts of straw,:}: dried in air, contain 38 per cent,
of carbon ; therefor:^, 1780 lbs. of straw contain 676 lbs. of
carbon. One hundred parts of corn contain 43 parts of carbon;
800 lbs. must therefore contain 344 lbs. ; in all 1020 lbs. of
carbon.

* 100 parts of hay, dried at 100° C (212° F.) and burned with oxide of
copper in a stream of oxygen gas, yielded 5r93 water, 166 8 caihonicacid,
and 6S2 of ashes. This gives 45 87 carbon, 5*76 hydrogen. 41*55 oxygen,
and 6 82 ashes. Hay, dried in the air, loses ir2 p. c. waterat 100<* C.
(212° F.)— Dr. Will.

t I. 0*8075 of dry beet gave 0*416 water and 1*155 carbonic acid. II
0*400 gave 0*201 water, and 0*595 carbonic acid. — Dr. Will.

I Straw analysed in the same manner, and dried at 100° C, gave 46*3*7
.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.— Db.
Will.

13 OF THE ASSIMILATION OF CARBON.

26,910 square feet of wood-land produce of carbon . 1007 lbs.

«* " meadow-land " . . 1018 lbs.

«* '« arable-land, beet-roots without leaves 880 lbs.

•« " corn .... 1020 lbs.

It must be concluded from these incontestable facts, that equal
surfaces of cultivated land of an average fertility are capable
of producing equal quantities of carbon ; yet, how unlike have
been the different conditions of the growtli 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, carbon has not
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 leaves, 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 nutrition
of plants are changed by culture, — that the sources of carbon
for fruit or grain, and for grass or trees, in meadows and forests,
are difTerent.

It is not denied that manure exercises an influence upon the
development of plants ; but it may be affirmed with positive cer-
tainty, that to its carbon is not due the favorable influence which
it exercises, because we find that the quantity of carbon produced
by manured lands is not greater than that yielded by lands which
are not manured. The discussion as to the 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 atmosphere.

In attempting to explain the origin of carbon in plants, it has
never been considered that the question is intimately connected

FERTILITY OF DIFFERENT SOILS. 13

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 pre
ceded 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 two most
remarkable natural phenomena, which, by their reciprocal and
uninterrupted influence, maintain the life of individual animals
and vegetables, and the continued existence of both kingdoms of
organic nature.

One of these questions is connected with the invariable con-
dition 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
tliey must be ascribed to errors of observation.

Although the absolute quantity of oxygen contained in the
atmosphere appears very great when represented by numbers,
yet it is not inexhaustible. One man consumes by respiration
25 cubic feet of oxygen in 24 hours ; 10 cwt. of charcoal con-
sume 32,066 cubic feet of oxygen during its combustion, so that
a single iron furnace consumes annually hundreds of millions of
cubic feet ; and a small town like Giessen (with about 7000 in-
habitants) exacts 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 statement,
that the quantity of oxygen in the atmosphere does not diminish
in the course of ages* — that the air at the present day, for exam-

• If the atmosphere possessed, in its whole extent, the same density as it
does on the surface of the sea, it would have a height of 24,555 Parisian
feet; but it contains the vapor of water, so that we may assume its height
to be one geographical mile=22,843 Parisian feet. Now, the radius of the
eai-th is equal to 860 geographical miles ; hence the

Volume of the atmosphere=9,307,500 cubic miles.
Volume of oxygen . . =1,954,578 "
Volume of carbonic acid =3,862"7 "

A man daily consumes 45,000 cubic inches (Parisian) of oxygen A maa

14 OF THE ASSIMILATION OF CARBON.

pie, does not contain less oxygen than that found in jars buried for
1800 years in Pompeii — appears quite incomprehensible, unless
some cause exists capable of replacing the oxygen abstracted.
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 produced during the respira-
tion 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, are immediately supplied
by the same number of billions of cubic feet of carbonic acid.

The most exact and trustworthy 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 obtained, the pro-
portion of carbonic acid in the atmosphere may be regarded as
nearly equal to nMro" P^^*^ ^f its weight. The quantity varies
according to the seasons ; but the yearly average remains cor^
tinually the same.

We have reason to believe that this proportion was much
greater in past ages ; and nevertheless, the immense masses of
carbonic acid which annually flow into the atmosphere from sc
many causes, ought perceptibly to increase its quantity from year
to year. But we find that all earlier observers describe its

yearly consumes 9505*2 cubic feet. 1000 million men yearly consume
9,505,200,000,000 cubic feet (Parisian).

Without exaggeration we may suppose that double this quantity is con-
Rumed in the support of respiration of the lower animals, and in the pro-
cesses of decay and combustion. From this it follows, that the annual con-
sumption of oxygen amounts to 2*392355 cubic miles, or in round numbers
to 2"4 cubic miles Thus, every trace of oxygen would be removed from
the atmosphere in 800,000 years. But it would be rendered quite unfit for
the support either of respiration or combustion in a much shorter time.
When the quantity of oxygen in the air is diminished 8 per cent., and the
oxygen thus abstracted is replaced by its own yolume of carbonic acid, the
latter exerts a fatal action upon animal life, and extinguishes the combiis-
tion of a burning body.

QUANTITY OF OXYGEN IN THE ATMOSPHERE. 1£

▼olume 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 invariable quantities of carbonic acid
and oxygen in the atmosphere, 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 removed
from the air by the processes of combustion and putrefaction, as
well as by the respiration of animals.

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

The facts which we have stated in the preceding pages prove
that the carbon of plants must be derived exclusively from the
atmosphere. Now, carbon exists in the atmosphere only in the
form of carbonic acid, and therefore in a state of combination
with oxygen.

It has been already mentioned, that carbon and the elements of
water form the principal constituents of vegetables ; the quantity
of the substances which do not possess this composition being in
a very small proportion. Now, the relative quantity of oxygen
in the whole mass is less than in carbonic acid ; for the latter
contains two equivalents of oxygen, whilst one only is required
to unite with hydrogen in the proportion to form water. The
vegetable products containing oxygen in larger proportion than
this, are, comparatively, few in number ; indeed, in many the
hydrogen is in great excess. It is obvious, that when the hydro-
gen of water is assimilated by a plant, the oxygen in combination
with it must be liberated, and will afford a quantity of this ele-
ment sufficient for the wants of the plant. If this be the case,
the oxygen contained in the carbonic acid is quite unnecessary in
the process of vegetable nutrition, and it will consequently escape
into the atmosphere in a gaseous form. It is therefore certain,
that plants must possess the power of decomposing carbonic acid,
since they appropriate its carbon for their own use. The forma-
tion of their principal component substances must necessarily be
attended with the separation of the carbon of the carbonic acid
from the oxygen, which must be returned to the atmosphere,
whilst the carbon enters into combination with water or its ele-

16 OF THE ASSIMILATION OF CARBON.

ments. The atmosphere must thus receive a volume of oxygen
for every volume of carbonic acid, the carbon of which has be-
come a constituent of the plant.

This remarkable property of pla/its has been demonstrated 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 independently 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 sun's light, the carbonic acid is, after a time,
found to have disappeared entirely from the water. If the ex-
periment is conducted under a glass receiver filled with water,
the oxygen emitted from the plant may be collected and examined.
When no more oxygen gas is evolved, it is a sign that all the
dissolved carbonic acid is decomposed ; but the operation recom-
mences if a new portion of it is added.

Plants do not emit gas when placed in water either free from
carbonic acid, or containing an alkali that protects it from assi-
milation.

These observations were first made by Priestley and Senne-
bier. 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 ele-
ments 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 con-
ceived without the concurrence of animal life, but the existence
of animals is undoubtedly dependent upon the life and develop-
ment 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 pro-
cess of respiration ; for, besides separating all noxious matters
from the atmosphere, they are an inexhaustible source of pure

ITS SOURCE THE ATMOSPHERE. 17

oxygen, and they thus supply to the air the loss constantly sus-
tained by it. Animals, on the other hand, expire carbon, while
plants inspire it ; and thus the composition of the atmosphere,
the medium in which both exist, is maintained constantly un-
changed. ,

It may be asked — Is the quantity of carbonic acid in the atmo-
sphere, scarcely amounting to 1-lOth per cent., sufficient for the
wants of the whole vegetation on the surface of the earth, — is it
possible that the carbon of plants has its origin from the air alone ?
This question is very easily answered. It is known that a
column of air of 1427 lbs. weight rests upon every square Hes-
sian foot (=0-567 square foot English) of the surface of the
earth ; the diameter of the earth and its superficies are likewise
known, so that the weight of the atmosphere can be calculated
with the greatest exactness. The thousandth-part of this is car-
bonic acid, which contains upwards of 27 per cent, carbon. By
this calculation it can be shown, that the atmosphere contains
3085 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 existing on the earth. This carbon is, therefore,
more than adequate to supply all the purposes for which it is re-
quired. The quantity of carbon contained in sea-water is pro-
portionally still greater.

If, for the sake of argument, we suppose the superficies 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 much under the truth in the
case of woods, meadows, and corn-fields — let us further sup-
pose, that from a stratum of air two feet thick, resting on an acre
(Hessian) of land, that is, from 80,000 cubic feet (Hessian) of
air, there is absorbed in every second of time, for eight hours
daily, carbonic acid equal to 0.00067 of the volume of the air,
or ToVo'^h of its weight ; then those leaves would receive above
1000 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 cnlculation. During the white-
washing of a small chamber, the siuperficies of the walls and roof of which
we will suppose to be 1 05 square metres, and which receives six coats of

18 OF 1H£ 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, as long as
those organs are not exposed to the action of a process which
may counteract the performance of their proper functions. The
roots and other parts of it, possessing the ^me property, con-
stantly absorb water and carbonic acid. This power is inde-
pendent of solar light. During the night, carbonic acid is accu-
mulated in all parts of their structure ; and the decomposition of
the carbonic acid, the assimilation of the carbon, and the exha-
lation 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 ; arid the true formation of woody tissue commences
at the same time.

The atmosphere is constantly in motion, both horizontally and
vertically. The same spot is alternately supplied with air pro-
ceeding from the poles or from the equator. A gentle breeze
moves in an hour over six German miles, and in less than eight
days over the distance between us and the tropics or the poles.
When the vegetable kingdom in the temperate and cold zones
ceases to decompose the carbonic acid generated by the processes
of respiration and combustion, the proper, constant, and inex-
haustible sources of oxygen gas are the tropics and warm cli-
mates, where a sky seldom clouded permits the glowing rays of
the sun to shine upon an immeasurably luxuriant vegetation. In

lime in four days, carbonic acid is extracted from the air, and the lime is
consequently converted, on the surface, into a carbonate. It has been ac-
curately determined that one square decimetre receives in this way a coat-
ing of carbonate of lime weighing 0-732 grammes. Upon the 105 square
metres already mentioned tliere must accordingly be formed 7680 grammes
of carbonate of lime, which contain 432 )"6 grammes of carbonic acid.
The weight of one cubic decimetre of carbonic acid being calculated at
two grammes (more accurately l-QTOVS), the above-mentioned surface must
absorb in four days 2'193 cubic metres of carbonic acid, 2500 square me-
tres (one Hessian acre) would absorb, under a similar treatment, 51 i cubic
metres = 1S18 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 gro.'^in^;
upon the same space.

ITS SOURCE THE ATMOSPHERE. 19

our winter, when artificial warmth must replace deficient heat
of the sun, carbonic acid is produced in superabundance, and is
expended in tlie nourishment of tropical plants. The great
stream of air, which is occasioned by the heating of the equator-
ial regions and by the revolution of the earth, carries with it in
its passage to the equator the carbonic acid generated during our
winters ; and, in its return to the polar regions, brings with it the
oxygen produced by the tropical vegetation.

The experiments of De Saussure have proved, that the uppei
strata of the air contain more carbonic 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 interchange of air between the upper and lower strata, caused
by their difference of temperature, is extremely trifling when
compared witli the horizontal movements of the winds. Thus
vegetable culture heightens the healthy state of a country, so
that a previously healthy country would be rendered quite unin-
habitable by the cessation of all cultivation.

The various layers of wood and mineral coal, as well as peat,
form the remains of a primeval vegetation. The carbon con-
tained in them 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 equal in volume to the carbonic acid abstracted in the
nourishment of a former vegetation, and must, therefore, corres-
pond to the quantity of carbon and hydrogen contained in the
carboniferous deposit. Thus, by the deposition of ten cubic feet
Flessian (5-51 cubic feet English) of Newcastle splint coal (of
the formula Cj 4H , 3O, and specific gravity 1228), the atmosphere
must have been deprived of above eighteen thousand cubic feet
Hessian (9918 cubic feet English) of car/Donic acid, and must
'nave been enriched with the same tpiantity of oxygen. A further

20 OF THE ASSIMILATION OF CARBON

quantity of oxygen amounting to 4480 cubic feet Hessian (2468
English) must have been furnished to the air by the decomposi-
tion of water, for 10 cubic feet Hessian of coal contains hydro-
gen corresponding to this amount. 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 ; q
circumstance which accounts for the richness and luxuriance of
the earlier vegetation. When this became entombed, the condi-
tions were established, under which higher forms of animal life
were capable of existing. (Brogniart.)

But a certain period must have arrived in which the quantity
of carbonic acid contained in the air experienced neither increase
nor diminution in any appreciable quantity. For if it received
an additional quantity to its usual proportion, an increased vege-
tation 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 stand-
ard. When man appeared on the earth, the air was rendered
constant in its composition.

The most important function in the life of plants, or, in other
words, in their assimilation of carbon, is the separation, we
might almost say the generation, of 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 ; because the assimilation of such a substance could be
effected without the exercise of this function. The reverse is
the case in the nutrition of animals. Hence such substances,
as sugar, starch, and gum, themselves the products of plaat^,
cannot be adapted for assimilation. And this is rendered certaui
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.

In the second part of the work we shall adduce satisfactory
proofs that decayed Moody fibre (humus) contains carbon and the
elements of water, without an excess of oxygen ; its composition

SEPARATION OF OXYGEN. 91

(in 100 parts) differing from that of woody fibre only in its being
richer in carbon.

Misled by this sinmplicity in its constitution, physiologists found
no difficulty in discovering the mode of the formation of woody
fibre ; for they say,* humus 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 suffi-
ciently demonstrated the inaptitude of these substances for assimi-
lation. Yet we could scarcely conceive a form more fitted for
assimilation than that of the substances just mentioned. They
contain all the elements of woody fibre, and with respect to
their composition in 100 parts, they correspond closely with
humus ; but they do not nourish plants.

All the erroneous opinions concerning the modus operandi of
humus have their origin in the false notions entertained respect-
ing 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., containing carbon and
the elements of water, are products of the life of plants which
live only whilst they generate them. The same may be said of
humus, for it can be formed in plants like the former substances.
Smithson, Jameson, and Thomson, found that the black excre-
tions of unhealthy elms, oaks, and horse-chestnuts, consisted of
humic acid in combination with alkalies. Berzelius detected
similar products in the bark of most trees. Now, can it be sup-
posed 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 many bota-
nists and vegetable physiologists, and that by the greater number
y.Q purification of the air by means of them is wholly denied ?

'Ihese doubts have arisen from an erroneous consideration of

* Meyen, Pflanzenphysiologie, II., S. 141.

OF THE ASSIMILATION OF CARBON.

the behavior of plants during the night. The experiments of
Ingenhouss were in a great degree the cause of the uncertainty
of opinion regarding the influence of plants in purifying the air.
His observation that green plants emit carbonic acid in the dark,
led De Saussure and Grischow to new investigations, by which
they ascertained that under such conditions plants do really
absorb oxygen and emit carbonic acid ; but that the whole volume
of air undergoes diminution at the same time. From the latter
fact it follows, that the quantity of oxygen gas absorbed is greater
than the volume of carbonic acid separated ; for, if both were
equal, no diminution could occur. These facts cannot be doubt-
ed, but the views based on them have been so false, that nothing,
except the total disregard and the utmost ignorance of the chemi-
cal relations of plants to the atmosphere, can account for their
adaption.

It is known that nitrogen, hydrogen, and a number of other
gases, exercise a peculiar, and, in general, an injurious influence
upon living plants. Is it, then, probable, that oxygen, one of the
most energetic agents in nature, should remain without influence
on plants when one of their peculiar processes of assimilation
has ceased ?

It is true that the decomposition of carbonic acid is arrested by
absence of light. But then, namely, at night, a true chemical
process commences, in 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 connected 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 calcu-
late which of them, during life, should absorb most oxygen by
chemical action when the influence of light is withdrawn.

The leaves and green parts of all plants containing volatile
oils or volatile constituents in general, should absorb more than
other parts free from such substances ; for these change into resin
by the absorption of oxygen. Leaves, also, containing either the
constituents of nut-galls, or compounds in which nitrogen is
present, ought to absorb more oxygen than those destitute of such

INFLUENCE OF THE SHADE ON PLANTS. 25

matters. The correctness of these inferences has been distinctly
proved by the observations of De Saussure ; for whilst the taste-
less and inodorous fleshy leaves of the Agave Americana absorb
only 0.3 of their volume of oxygen in the dark, during twenty-
four hours, the leaves of the Pinus Abies, containing volatile and
resinous oils, absorb ten times ; those of the Quercus Robur con-
taining tannic acid 14 times ; and the balmy leaves of the Popu-
lus alba 21 times that quantity. This chemical action is shown
very plainly also in the leaves of the Cotyledon calycinum, the
Cacalia f,coides, and others ; for they are sour like sorrel in the
morning, tasteless at noon, and bitter in the evening. The forma-
tion of acids is effected during the night by a true process of oxi-
dation ; they 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 ; for such 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 continuing longest green will abstract
less oxygen from the air in an equal space of time, than those
the constituent parts of which sufTer a more rapid change. It is
found, for example, that the leaves of the Ilex aquifolium, distin-
guished by the durability of their color, absorb only 0.86 of their
volume of oxygen gas in the same time that the leaves of the
poplar absorb 8, and those of the beech 9^ times their volume :
both the beech and poplar being remarkable for the rapidity and
ease with which the color of their leaves changes. (De
Saussure.)

When the green leaves of the beech, the oak, or the holly, are
dried under the air-pump, 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 diminution of the gas which occurs can only
be owing to the union of a large proportion of oxygen with

M OF THE ASSIMILATION OF CARBON.

those substances already in the state of oxides, or to the oxida-
tion of such vegetable compounds as contain hydrogen in excess.
The fallen brown or yellow leaves of the oak contain no longer
tannin, and those of the poplar are destitute of balsamic consti-
tuents.

The property possessed by green leaves of absorbing oxygen
belongs also to fresh wood, whether taken from a twig or from
the interior of the trunk of a tree. When fine chips of such wood
are placed in a moist condition under a jar filled with oxygen,
the gas is seen to diminish in volume. But wood, dried by ex-
posure to the atmosphere and then moistened, converts the
oxygen into carbonic acid, without change of volume ; fresh
wood, therefore, absorbs most oxygen.*

MM. Petersen and Schodler have shown, by the careful ele-
mentary 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 lOOc* C. (212=^ F.), contains 49*432 carbon, 6-069
hydrogen, and 44*499 oxygen.

The proportion of hydrogen necessary to combine with 44*499
oxygen in order to form water, is J of this quantity, namely
5-56 ; it is evident, therefore, that oak wood contains -,\ more
hydrogen than corresponds to this proportion. In Pinus larix,
P. abies, and P. picea, the excess of hydrogen amounts to -f , and
in Tilia europea 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 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,

* When villages situated on the banks of rivers become inundated with
floods, this property of wood gives rise to much disease. The wood of the
floors and the rafters of the building become saturated with water, which
evaporates very slowly. The oxygen of the air is absorbed rapidly by
the moist wood, and carbonic acid is generated. The latter gas exercise;
a directly pernicious influence when present in air to the amount of 7 at
8 per cent.

EVOLUTION OF CARBONIC ACID DURING THE NJGHT. 25

upon the presence of constituents, in part soluble, and in part
insoluble, such as resin and other matters, containing a large
proportion of hydrogen : the hydrogen of such substances being
in the analysis of the various woods added 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. If, in its present state, its further decay does not
alter the volume of the air, it is certain that in the beginning of
the process the result must have been different, for the amount
of hydrogen present in the fresh wood has been diminished, and
this could only have been eifected by an absorption of oxygen.

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 respiration 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 un-
stable foundation.

The carbonic acid, which has been absorbed by the leaves
and by the roots, together with water, ceases to be decomposed
on the departure of daylight ; it is 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, contains a certain
quantity of moisture indispensably necessary to their existence.
Carbonic acid, likewise, is always present in such a soil,
whether it has been abstracted from the air, or has been gene-
rated 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 or car-
bonic acid. Is it, therefore, surprising that the carbonic acid
should be returned unchanged to the atmosphere along with
water, in the absence of light ; for this is known to be the cause
of the fixation of its carbon ?

Neither this emission of carbonic acid nor the absorption of
3

2G ON THE ASSIMIL.iTION OS CARBON.

oxygen has any connexion with the process of assimilation, nor
have they the slightest relation to one another ; the one is a
purely mechanical, the other a purely chemical process. A
cotton wick, inclosed in a lamp containing 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 living in a moist soil containing humus exhale much
more carbonic acid during the night than those growing in dry
situations ; they also yield more in rainy tlian in dry weather ;
these facts point out to us the cause of the numerous contra-
dictory observations made with respect to the change impressed
upon the air by living plants, both in darkness and in common
daylight ; but these contradictions are unworthy of considera-
tion, as they do not assist in the solution of the main question. -

There are other facts which prove in a decisive manner that
plants yield more oxygen to the atmosphere than they extract
from it. These proofs may easily be obtained, without having
recourse to any peculiar arrangements, from observations made
on plants living under water.

Pools and ditches, the bottoms of which are covered with
growing plants, often freeze upon their surface in winter, so
that the water is completely excluded from the atmosphere by
a clear stratum of ice ; under such circumstances small bubbles
of gas are observed to escape continually during the day, from
the points of the leaves and twigs. These bubbles are seen
most distinctly when the rays of the sun fall upon the ice ; they
are very small at first, but collect under the ice and form largei
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 carbonic acid absorbed by the plants from the
water, to which it is again supplied 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.

EVOLUTION OF CARBONIC ACID DURING THE NIGHT. 21

Sir H. Davy made an elegant experiment in illustration of the
facts just stated. He placed a turf, four inches square, in a
porcelain dish which swam on the surface of water impregnated
with carbonic acid gas. A glass vessel of the capacity of 230
cubic inches was made to cover the grass, to which water was
occasionally supplied by a funnel furnished with a stopcock.
The water upon which the porcelain dish swam was daily sup-
plied with new water saturated with carbonic acid, so that a
small quantity of that gas must always have been present in the
receiver. The volume of air in the receiver was found to in-
crease by exposure to daylight, so much so, that after the lapse
of eight days, an increase of thirty cubic inches was observed.
The air inside the receiver on being analysed was found to con-
tain 4 per cent, more oxygen than the air of the exterior
atmosphere. (Davy's Agricultural Chemistry, Lecture V.) In
confirmation of the same facts we may also refer to the excellent
experiments of Dr. Daubeny.*

In the preceding part of the work, we have furnished proofs
that the carbon of plants is derived from the atmosphere. We
have yet to consider the action of humus and of certain mineral
matters upon the development of vegetation, and also the source
whence plants receive their nitrogen.

* On the Action of Light upon Plants, : nd of Plants upon the Atmos-
phere, PhiL Trans., Part I., 1836

'A ON THE ORIGIN AND ACTION OF HUMUS.

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^ or putrefaction ;
the other decay or eremacausis.*

It will likewise be shown, that decay is a slow process of com-
bustion,— a process, therefore, in which the combustible parts of'
a plant unite with the oxygen of the atmosphere.

The decay of woody fibre (the principal constituent of all
plants) is accompanied by a phenomenon of a 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 be
removed, and oxygen replaced, its decay recommences, that is,
it again converts oxygen into carbonic acid. Woody fibre con-
sists 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 anti-
septic substances, such as sulphurous acid, the mercurial salts,
empyreumatic oils, &c., cause its complete cessation.

• The word eremacausis was proposed by the author some time since,
in order to explain the true nature of decay ; it is compounded from
hpif^*t by degrees, and lavais, burning.

IT EVOLVES CARBONIC ACID. 39

Woody fibre in a state of decay is the substance called

HUMUS.*

The property of woody fibre to convert surrounding oxygen
gas into carbonic acid diminishes in proportion as its decay
advances, and at last a certain quantity of a brown coaly-looking
substance remains, in which this property is entirely wanting.
This substance is called mould ; it is the product of the complete
decay of woody fibre. Mould constitutes the principal part of
all the strata of brown coal and peat. By contact with alkalies,
such as lime or ammonia, a further decay of mould is occa-
sioned.

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 atmosphere 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 unobstructed 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 growing upon it.

In spring, when those organs of plants are absent which nature
has appointed for the assumption of nourishment from the atmo-
sphere, the component substances of the seeds are exclusively
employed in the formation of the roots. Eacii new radicle fibril
acquired by a plant may be regarded as constituting 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 surrounding young plants, we favor the
access of air, and the formation of carbonic acid ; and, on the
other hand, the quantity of their food is diminished by every
difficulty which opposes the renewal of air. A plant itself effects
this change of air at a certain period of its growth. The car-
bonic acid, which protects the undecayed humus from further

* The humic acid of chemists is a product of the decomposition of
humus by alkalies ; it does not exist ia the humus of vegetable physiolo-

ON THE ORIGIN AND ACTION OF HUMUS.

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, which, by its oxygen, renews the process of decay,
and forms a fresli portion of carbonic acid. A plant at this time
receives its food both by the roots and by the organs above
ground, and advances rapidly to maturity.

When a plant is quite matured, and when the organs by which
it obtains food from the atmosphere are formed, the carbonic acid
of the soil is no further required.

Deficiency of moisture in the soil, or its complete dryness,
does not now check the growth of a plant, provided it receives
from the dew and from the atmosphere as much as is requisite for
the process of assimilation. 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 curiosities, which have been reared by Chinese
gardeners, and are only one foot and a half in height, although
their trunks, barks, leaves, branches, and whole habitus, evince
a venerable 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 which a plant acquires in a given time is pro-
portional to the surface of the organs destined to convet
GOOD TO IT. When the surfaces of two plants are equal, their
increase depends upon the length of time that their absorbing
powers remain in activity. The absorbing surfaces of fir trees
are active during the greater part of the year, so that (ccBteris
paribus), they increase more than those trees which part with
their foliage in autumn. Each leaf furnishes to a plant another
mouth and stomach.

The power possessed by roots of taking up nourishment 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

• Teltow is a village near Berlin, where small parsneps are cultivated
in a Bandy soil : they are much esteemed, and weigh rarely above on«
ounce.

GROWTH OK PLANTS. 31

'"e:*"?-' development, the superfluous nutriment is not returned to
r>ie soil, but is employed in the formation of new organs. The
conc.nued supply of carbonic acid by means of a soil rich in
numus must exert a very marked influence on the progressive
t evelopment of the plant, provided the other conditions necessary
to the assimilation of carbon are also present. 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
development of the buds, green sprouts, and leaves.

The power of absorbing nutriment from the atmosphere, 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 nutri-
tive 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 tho
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 nutritive matters from the atmo-
sphere, and, with the aid of light and moisture, to appropriate
their elements. These processes are continually in operation :
they commence with the first formation of the leaves, and do not
cease with their perfect developme*?.l. But the new products
arising from this continued assimilation are no longer employed
by the perfect leaves in their own increase : they serve for the
formation of woody fibre, and all the solid matters of similar
composition. The leaves now produce sugar, amylin or starch,
and acids, which were previously formed by the roots when they
were necessary for the development of the stem, buds, leaves,
and branches of the plant.

The organs of assimilation, at this period of their life, receive
more nourishment from the atmosphere than they employ in their

32 ON THE ORIGIN AND ACTION 01' HUMUS

own sustenance ; and when the formation of the woody suv
stance has advanced to a certain extent, the expenditure of the
nutriment, the supply of which still remains the same, takes &
new direction, and blossoms are produced. The functions of the
leaves of most plants cease upon the ripening of their fruil;
because the products of their action are no longer needed. They
now yield to the chemical influence of the oxygen of the air,
generally sutlor a change in color, and fall off.

A peculiar transformation of the matter contained in all
plants takes place in the period between blossoming and the
ripcniiig of the fruit ; new compounds are produced, which
furnish constituents: to the blossoms, fruit, and seeds.

Transforiiiiitions of existing compounds are constantly taking
place during t!ie 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 blossoms,
solid excrements deposited in the bark, and fluid soluble substan-
ces which are eliminated by the roots. Such secretions are most
abundant immediately belbre 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
receives again the greater part of the carbon which it had at first
yielded to the young plants as food, in the form of carbonic acid.

The soluble matter thus acquired by the soil is still capable
of decay and putrefaction, and, by undergoing tl ese process s,
furnishes renewed sources of nutrition to another generation of
plants; it becomes humus. The fallen leaves of trees, and the
old roots of grass in the nu adow, are likewise converted into
humus by the same influence.

The carbon contained in the roots of annual plants, such as
the corn plants and culinary vegetables, is without doubt derived
principally from the atmosphere. But after the removal of the
crop, their roots remain in the soil, and, undergoing putrefiction
and decay, furnish hunms, or that sut -stance which is able to
yield carbonic acid to a new vegetation. A soil receives more

NOT INDISPENSABLE FOR PLANTS. 33

carbon in this form, than its decaying humus had formerly loit
in carbonic acid.

Plants do not exhaust the carbon of a soil in the normal con-
dition of their growth ; on the contrary, they add to its quantity.
But if it be true that plants give back more carbon to a soil than
they take from it, it is evident that the amount of carbon which
is removed in any shape in the crop must have been derived from
the atmosphere in the form of carbonic acid. It is well known
that springs occurring in gardens of the richest vegetable mould,
furnish clear and perfectly colorless water destitute both of
humus and of salts of humic acid. It is likewise known that
humates cannot be detected in the springs of meadows, in the
waters of our rivers, or even in acidulous mineral waters,
although they contain a considerable quantity of alkaline salts.
Now a simple consideration of these facts proves to us either that
the richest vegetable mould is free from humic acid, or that this
acid cannot be absorbed by plants through the agency of water.
Hence it follows that the common view of the action of humus is
erroneous. The water resting upon a meadow is found to be
iich in carbonic acid and alkaline bases. Well-water also gene-
rally contains much of the former ingredient. The influence,
ihen, of humus or decaying vegetable matter upon vegetation, is
explained by these facts in the most clear and satisfactory man-
ner. Humus, therefore, does not nourish plants by being assimi-
lated in its soluble state, but by furnishing a gradual and conti-
nued source of carbonic acid. This gas forms the chief means of
nourishment to the roots of plants, and is constantly formed anew
as long as the soil admits the free access of air and moisture,
these being the necessary conditions for effecting the decay ot
vegetable matter.

The verdant plants of warm climates are very often such as
obtain from the soil only a point of attachment, and are not de*
pendent on it for their growth. How extremely small are the
roots of the various species of Cactus,* Sedum, and Sempervivum,

* The Cactus" was probably introduced into Sicily by the Spaniards. It

forms as important an article of diet with the inhabitants of that island as

the potatoe does with ourselves. This abundant, cooling, and juicy fruit

fcrms the principal food of the lower classes for three months, and is con-

3*

94 ON THE ORIGIN AND ACTION OF HTTMUS.

in proportion to their mass, and to the surface of their leaves !
Large forests are often found growing in soils absolutely desti-
tute of carbonaceous matter : and the extensive prairies of the
Western Continent show that the carbon necessary for the suste-
nance of a plant may be entirely extracted from the atmosphere.
Again, in the most arid and barren sand, where it is impossible
for nourishment to be obtained through the roots, we see the
milky-juiced plants attain complete perfection. The moisture
necessary for the nutrition of these plants is derived from the
atmosphere, and when assimilated is secured from evaporation
by the nature of the juice itself. Caoutchouc and wax, which
are formed in these plants, surround the water, as in oily emul-
sions, with an impenetrable envelope by which the fluid is
retained, in the same manner as milk is prevented from evapo-
rating by the skin which forms upon it. The plants become
turgid with their juices.

sidered very palatable, although strangers usually find it insipid. The
hills of Palermo covered with the Cactus correspond to our corn-fields.
It is a very important plant for such districts, because its roots easily enter
into the cracks and crevices of the volcanic rocks. These, although
destitute of humus, soon acquire it by the decay of the leaves, and thus
fertile soils are gradually formed for other plants. {A^utlandcy S. 274,
3d October, 1842.)

ASSIMILATION OF HYDROGEN,

CHAPTER IV.

Oil 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 consti-
tuents of water, or the elements of carbonic acid, together with a
certain quantity of hydrogen. It has formerly been n)entioned
that water consists of the two gases, oxygen and hydrogen. We
can conceive tlic wood to arise from a combination of the
carbon of the carbonic acid with the elements of water, under
the influence of solar light. In this case, 72-.35 parts of oxygen,
by weight, must be separated as a gas for every 27-65 parts of
carbon assimilated by a plant ; for this is the composition of car-
bonic acid in 100 parts. Or, what is much more probable,
plants, under the same circumstances, may decompose water, in
which case the hydrogen would be assimilated along with car-
bonic acid, whilst its oxygen would be separated. If the latter
change takes place, 9*77 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 vater, and which exactly corresponds in
;juantity with the oxygen contained in the carbonic acid, must
be separated in a gaseous form.*

Each acre of land, producing 10 cwts. of carbon, gives

* As far as regards the final results, it is a matter of perfect indiffer-
ence to which of these views we accord the preference. Hence we will
use both occasionally. The decomposition of carbonic acid, as well as
that of water, must be supposed in the formation of those compounds
in which oxygen is either entirely absent or insufficient to form water
with the hydrogen.

36 ASSIMILATION C^i-' HYDROGEN.

annually to the atmosphere 2865 lbs., or 32,007 cubic feet of
free oxygen gas.*

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

It has been mentioned in a former part of the work that pure
woody fibre contains carbon iind the component parts of water,
but that ordinary wood contains more hydrogen than corresponds
to this proportion. This excess is owing to the presence of the
green principle of the leaf, wax, oil, resin, and other bodies rich
in hydrogen. Water must be decomposed, in order to furnish
the excess of this element, and consequently one equivalent of
oxygen must be given back to the atmosphere for every equiva-
lent of hydrogen appropriated by a plant to the production of
those substances. The quantity of oxygen thus set at liberty
cannot be insignificant, for the atmosphere must receive above
100 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 pro-
portional quantity of oxygen ; and that the volume of this gas
set free would be the same whether it were due to the decompo-
sition of carbonic acid or of water. It was considered most pro-
bable that the latter was the case.

From their generating caoutchouc, wax, fats, and volatile oils
containing hydrogen in large quantity, and little oxygen, we may
be certain that plants possess the property of decomposing
water, because from no other body could the unazotized sub-
stances obtain their hydrogen. It has also been proved by the
observations of Humboldt on the fungi, that water may be decom-
posed without the assimilation of hydrogen. Water is b remark-
able combination of two elements, which have the power to sepa-
rate themselves from one another^ in innumerable processes, in
a manner imperceptible to our senses ; while carbonic acid,

• The specific weight of oxygen is expressed by the number ri026 ;
hence, 1 cubic metre of oxygen weighs 3-157 lbs., and 2865 lbs. of oxygen
conespond to 90S cubic metres, or 32,007 cubic feet

\SSIMILATION OF HYDROGEN.

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 essential to their constitution cannot
possibly exist in the state of water.

All the hydrogen necessary for the formation of an organic
compound is supplied to a plant by the decomposition of water.
The process of assimilation, in its most simple form, consists in the
extraction of hydrogen from water, and of carbon from carbonic
acid, in consequence of which, either all the oxygen of the
water and of the carbonic acid is separated, as in the formation
of caoutchouc, the volatile oils containing no oxygen, and other
similar substances, or only a part of it is exhaled.

The known composition of the organic compounds most gene-
rally present in vegetables, enables us to state in definite propor
tions the quantity of oxygen separated during their formation.

36 eq. carbonic acid and 22 eq. hydrogen derived ) __ tj/-^^^.. wihre *

from 22 eq. water S

with the separation of 72 eq. oxycren.
3G eq. carbonic acid and 36 e'j. hydrogen derived ) ^==.Suear
from 36 eq. water ----- 3 & •

with the separation of 72 eq. oxygen.
36 eq. carbonic acid and 30 eq. hydrc^ea derived > =: starch

from 30 eq. water >

with the separation of ^2 eq. oxygen.
36 eq. carbonic acid and lJi3 eq. hrlroge.i derived ) =:2^annic Acid

from 16 eq. water )

with the separati jii of 64 eq oxygen.
36 eq. carbonic acid and 18 eq. hydrogen derived ) _ tt^^^^^-^ jj^id

from 18 eq. water )

with the separation of 4-5 eq. oxygen.
36 eq. carbonic acid and IS eq. hydrogen derived > _ j^ff^n^ ^q^td

from 18 eq. water )

with the separation of 54 eq. oxygen.

* It is evident that both carbonic acid and water must be decomposed
to yield woody fibre of the above composition, C3 g H2 2 O2 2 ; that is, if
water is here decomposed. For 22 eq. of water can only yield 22 eq. of
oxygen ; and, therefore, supposing all the water to be decomposed, 25 of
the 36 eq of carbonic acid must also be decomposed, to yield, with the
oxygen of the 22 eqs. of water, 72 eq, of oxygen. The remaining 11 eqs.
of carbonic acid with the carbon of the 25 eq. decomposed, and the 22 eqs
of hydrogen will then yield the residue C 3 6 Ha 2 O2 2.

ASSIMILATION OF HYDROGEN.

30 eq. carbonic acid and 24 eq. hydrogen derived ) =Oil ofTuroenttne

from 24 eq. water 5 J P

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, repre-
sented by the numbers above cited.

The green resinous principle of the leaf diminishes in quan-
tity, 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. oxygen
from the air, form grape sugar, with the separation of 12 eq.
carbonic acid, 1 eq. Tannic Acid, by absorbing 8 eq. oxygen
from the air, and 4 eq. water, form 1 eq. of Amylin, or starch,
with separation of 6 eq. carbonic acid.

We can explain, in a similar manner, the formation of all the
unazotized component substances of plants, whether they are
produced from carbonic acid and water, with the 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 r^ot know in what form the production ofthe.se constitu-
ents takes place ; in this respect, the representation of their
fDrmation which we have given must not be received in an
absolute sense, it being intended only to render the nature of
the process more capable of apprehension ; but i' 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 hU cir-
cumstances in the proportions aMve mentioned.

The vital process in plants is, vjth reference to the point we
have been considering, the converse of the chemical processes
engaged in the formation of salts. Carbonic acid, zinc, and

ATTENDED WITH EVOLUTION OF OXYGEN. 39

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
contain the elements of carbonic acid and the hydrogen of
water, whilst oxygen is separated.

Decay has been described above as the great operation of na-
ture, by which that oxygen which was assimilated by plants
during life, is again returned to the atmosphere. During the
progress of growth, plants appropriate carbon in the form of
carbonic acid, and hydrogen from the decomposition of water,
•he oxygen of which is set free, together with a part or all of
ihat contained in the carbonic acid. In the process of putrefac-
tion, a quantity of woter, exactly corresponding to that of the
hydrogen, is again formed by extraction of oxygen from the air ;
while all the oxygen of the organic matter is returned to the
atmosphere* in the fJ^rm of carbonic acid. Vegetahle matters
can emit carbonic acid, during their decay, only in proportion
to the quantity of oxygen which they contain ; acids, therefore,
yield more carbonic acid than neutral compounds ; while fatty
acids, resin, and wax, do not putrefy ; t ley remain in the soil
without any apparent change.

40 SOURCE AND ASSIMILATION OF NITROGEN.

CHAPTER V.

We cannot suppose that a plant could attain maturity, even in
the richest vegetable mould, without the presence of mattei
containing nitrogen ; since we know that nitrogen exists in
every part of the vegetable structure. The first and most im-
portant question to be solved, therefore, is : How and in what
form does nature furnish nitrogen to vegetable albumen, and' to
gluten, or to fruits and seeds ? *

This question is susceptible of a very simple solution.

Plants, as we know, grow perfectly well in a mixture of char-
coal and earth, previously calcined, if supplied at the same time
with rain-water. Rain-water can contain nitrogen only in three
forms, as dissolved atmospheric air, as nitric acid, or as ammonia.
Now, the nitrogen of the air cannot be made to enter into combi-
nation with any element except oxygen, even by the employment
of the most powerful chemical means. We have not the slight-
est reason for believing that the nitrogen of the atmosphere takes
part in the processes of assimilation of plants and animals ; on the
contrary, we know that many plants emit the nitrogen which is
absorbed by their roots, either in the gaseous form, or in solution
in water. But there are on the other hand numerous facts,
showing, that the formation in plants of substances containing
nitrogen, such as gluten, takes place in proportion to the quantity

* " It is certain," says Saussure, " from the experiments which have
been made on this point, that plants receive their nitrogen only from such
animal or vegetable extracts, or from such ammoniacal vapors as they may
find in the soil, or extract from the air. When plants are made to
vegetate by the aid of water in a confined atmosphere, we may presume
that the new parts can only obtain nitrogen at the expense of other parta
to which it had formerly been supplied." {^De Saussure, page 190.)

SOURCE AND ASSIMILATION OF NITROGEN. 41

of this element 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 pro-
perty 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 am-
monia changes, under the influence of a high temperature, into
hydrocyanic acid and water, without the separation of any of its
elements. Ammonia forms urea, with cyanic acid, 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 phloridzia, the bitter constituent of
the bark of the root of the apple-tree, with orcin, the sweet prin-
ciple of the Lichen dealhatus, or with erythrin, the tasteless matter
of the Rocella tinctoria. All blue coloring matters capable of
being reddened by acids, and all red coloring substances rendered
blue by alkalies, contain nitrogen, but not in the form of a base.

These facts are not sufficient to establish the opinion that it is
ammonia which affords all vegetables, without exception, the ni-
trogen 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 the 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 sub-
stance containing nitrogen. Now, the products of this farm
must be exchanged every year for money, and other necessaries
of life — for bodies, therefore, destitute of nitrogen. A certain
proportion of nitrogen is exported in tiie shape of corn and cat-

42 SOURCE AND ASSIMILATION OF NITROGEN.

tie : and this exportation takes place every year, without the
smallest compensation : yet after a given number of years, the
quantity of nitrogen will be found to have increased. Whence,
we may ask, comes this increase of nitrogen ? The nitrogen in
the excrements cannot reproduce itself, and the earth cannot yield
it. Plants, and consequently animals, must, therefore, derive
their nitrogen from the atmosphere. (Boussingault.)

It will in a subsequent part of this work be shown that the
last products of the decay and putrefaction of animal bodies pre-
sent themselves in two different forms. They are in the form of
ammonia (a combination of hydrogen and nitrogen), in the tem-
perate and cold climates, and in that of nitric acid (a compound
containing oxygen), in the tropics and hot climates. The forma-
tion of the latter is always preceded by the production of the
former. Ammonia is the last product of the putrefaction ,of
animal bodies ; nitric acid is the product of the decay or erema-
causis 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 contained in them during life ? There la
no question which can be answered with more positive certainty.
All animal bodies during their decay yield to the atmosphere
their nitrogen in the form of animonia. 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. Ammonia is the simplest of all
the compounds of nitrogen ; and hydrogen is the element for
which nitrogen possesses the most predominant affinity.

The nitrogen of putrefied animals is contained in the atmo-
sphere as ammonia, in the state of a gas which is capable of
entering into combination with carbonic acid, and of forming a
volatile salt. Ammonia in its gaseous form, as well as all its
volatile compounds, is of extreme solubility in water. Ammonia,
therefore, cannot remain long in the atmosphere, as every shower
of rain must effect its condensation, 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 contain
more in summer than in spring or in winter, because the inter

PRODUCTS OF PUTREFACTION. 43

vals 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 conveyed to the earth at one time.

But all the analyses of atmospheric air hitherto made have
failed to demonstrate the presence of ammonia, although, accord-
ing to our view, it can never be absent. Is it possible that it
could have escaped our most delicate and most exact apparatus ?
The quantity of nitrogen contained in a cubic foot of air, as am-
monia, is certainly extremely small, but, notwithstanding this,
the sum of the quantities of nitrogen from thousands and millions
of dead animals is more than sufficient to supply all those living
at one time with this element.

From the tension of aqueous vapor at 15° C. (59^ F.)=0,98
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 48-1 cubic
metres, or 1698 cubic feet of air ; 35-3 cubic feet of aqueous
vapor weigh about I5 lb. Consequently, if we suppose that
the air saturated with moisture at 59° F. allows all the water
which it contains in the gaseous form to fall as rain, then 1 pound
of rain. water must be obtained from every 1132 cubic feet of
air. The whole quantity of ammonia contained in the same
number of cubic feet will also be returned to the earth in this
one pound of rain-water. But if the 1132 cubic feet of air con-
tain a single grain of ammonia, then the few cubic inches usually
employed in an analysis must contain only 0-0000048 of a
grain. This extremely small proportion is absolutely inappre-
ciable 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 1132 cubic
foet of air.

If a pound of rain-water contain only ^th of a grain of am-
monki, then a field of 26,910 square feet must receive annually

44 SOURCE AND ASSIMILATION OF NITROGEN.

upwards of 80 lbs. of ammon.ia, or 65 lbs. of nitrogen; for by
the observations of Schubb r, formerly alluded to, the annual fall
must be about 2,520,000 lbs. This is much more nitrogen than
is contained in the form of vegetable albumen and gluten, in
2,650 lbs. of wood, 2,500 lbs. of hay, or 200 cwt. of beet-root,
which are the yearly produce of such a field ; but it is less than
the straw, roots, and grain of corn, which might grow on the
same surface, would contain.

Experiments made in this laboratory (Giessen) with the great-
est care and exactness, have placed the presence of ammonia in
rain-water beyond all doubt. It has hitherto escaped obser-
vation, because it was not searched for. All the rain-water em-
ployed in this inquiry was collected 600 paces south-west 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
addition of a little muriatic acid, a very distinct crystallization
of sal-ammoniac was obtained : the crystals had always a brown
or yellow color.

Ammonia may likewise be always detected in snow-water.
Crystals of sal-ammoniac were obtained by evaporating in a ves-
sel with muriatic acid several pounds of snow, which were ga-
thered from the surface of the ground in March, when the snow
had a depth of ten inches. Ammonia was set free from these
crystals by the addition of hydrate of lime. The inferior layers
of snow resting upon the ground contained a quantity decidedly
greater than those upon the surface.

It is worthy of observation that the ammonia contained in rain
and snow-water possesses an otfensive smell of perspiration and
putrefying matter, — a fact which leaves no doubt respecting its
origin.

Hunefield has proved that all the springs in Greifswalde, Wiek,
Eldena, and Kostenhagen, contain carbonate and nitrate of am-
monia. Ammoniacal salts have been discovered in many m'neral
springs in Kissingen and other places. The ammonia of these
salts can only arise from the atmosphere.*

• Pharmaceutical chemists are well aware of the existence of ammonU

EXISTENCE OF AMMONIA IN THE JUICES OF PLANTS. 45

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-water, and by evaporating this nearly to dryness
in a clean porcelain basin. The ammonia remains in the residue,
in combination with the acid employed ; and may be detected
either by the addition of a little chloride of platinum, or, more
simply, by a little powdered lime, which separates the ammonia;
and thus renders sensible its peculiar pungent smell. The sen-
sation 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 trie carbonate
of ammonia contained in the former.

The ammonia removed from the atmosphere by rain and other
causes, is as constantly replaced by putrefaction of animal and
and vegetable matters.* A certain portion of that which falls
with the rain evaporates again with the water ; but another por-
tion is, we suppose, taken up by the roots of plants, and entering
into new combinations in the different organs of assimilation,
produces, by the action of these and of certain other conditions,
albumen, gluten, and vegetable casein, or quinine, morphia,
cyanogen, and a numberof other compounds containing nitrogen.
The chemical characters of ammonia render it capable of enter-
ing into such combinations, and of undergoing numerous trans-
formations. 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 azotised
matters contained in them. This question is susceptible of easy
solution by well-known facts.

In the year 1834, I was engaged with Dr. Wilbrand, professor
)f botany in the University of Giessen, in an investigation re-
in well-water, for they have often to reject as much as one-fourth of the
water distilled, before they procure water which is not rendered turbid by
corrosive sublimate. But when phosphoric acid or alum is added to the
water previous to distillation, the product of the distillation is not affected
either by corrosive sublimate or by sugar of lead. (Wiegmann and Pot-
KTORr's Prize Essay on the Inorganic Ingredients of Plants.)

* " We cannot doubt," says Saussure, " that ammonia exists in the atmo-
sphere, for we know that sulphate of alumina is gradually converted int<
•mmoniacal alum by exposure to the air " {Rech. svr la Vigit.)

49 SOURCE AND ASSIMILATION OF NITROGEN.

specting the quantity of sugar contained in different varieties of
maple-trees, growing upon unmanured soils. We obtained crys-
tallized sugars from all, by simply evaporating their juices, with-
out the addition of any foreign substance ; and we unexpectedly
made the observation, that a great quantity of ammonia was emit-
ted from this juice when mixed with lime, in the process of refin-
ing, as practised with cane sugar. The vessels which hung upon
the trees in order to collect the juice were watched with the
greatest attention, on account of the suspicion that some evil-dis-
posed 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 crystallization. Every person who has entered such a manu-
factory must have been astonished at the great quantity of am-
monia volatilized along with the steam. This ammonia must be
contained in the form of an ammoniacal salt, because the neutral
juice possesses the same characters as the solution of such a salt
in water ; it acquires, namely, an acid reaction during evapora-
tion, in consequence of the neutral salt being converted by loss
of ammonia into an acid salt. The free acid 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 pur-
poses, contain ammonia. The unripe, transparent, and gelatinous
pulp of the almond 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

COMPOSITION OF EXCREMENTxTIOUS MATTER. 4T

yields a gummy deliquescent mass, which evolves much ammo,
nia 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 am-
monia, and therefore afford all the conditions necessary for the
formation of the azotised components of the branches, blossoms,
and leaves, as well as of those which contain no nitrogen. In
proportion as the development of those parts advances, the am-
monia diminishes in quantity, and when they are fully formed,
the tree yields no more juice.

The employment of animal manure in the cultivation of grain,
and the vegetables which serve for fodder to cattle, is the most
convincing proof that the nitrogen of vegetables is derived from
ammonia. The quantity of gluten in wheat, rye, and barley, is
very variable ; these kinds of grain also, even when ripe, con-
tain this compound of nitrogen in very different proportions.
Proust found French wheat to contain 12-5 per cent, of gluten ;
Vogel found that the Bavarian contained 24 per cent. ; Davy
obtained 19 per cent, from winter, and 24 from summer wheat ;
from Sicilian 21, and from Barbary wheat 19 per cent. The
flour 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, 33-3 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 niost remarkable difference in the proportion of the
substances contaming nitrogen, such as the gluten.

Animal manure exerts a very complex action on plants, but as
far as regards the assimilation of nitrogen, it acts only by the
formation of ammonia. One hundred parts of wheat grown on
a soil manured with cow-dung (a manure containing the smallest
quantity of nitrogen), afforded only 11-95 parts of gluten, and
62*34 parts of amy] in, or starch ; whilst the same quantity,

• In an experiment performed at my reqnp«»t in Calcutta, it was found
that the fresh juice of the palm tree abounded with ammonia, — Ed.

is SOURCE AND ASSIMILATION OF NIGROGEN.

grown on a soil manured with human urine, yielded the maxi-
mum of gluten, namely 35-1 percent., or nearly three times the
quantity. Putrefied urine contains nitrogen in the forms of
carbonate, phosphate, and muriate of ammonia, and in no other
form than that of ammoniacal salts.

Putrid urine is employed in Flanders as a manure, with the
best results. During the putrefaction of urine, ammoniacal salts
are formed in large quantity, it may be said exclusively ; for
under the influence of heat and moisture, urea, the most promi-
nent ingredient of the urine, is converted into carbonate of am-
monia. 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 consisting only of sand and clay, in
order to procure the richest crop of maize. The soil itself dops
not contain the smallest particle of organic matter, and the ma-
nure employed is formed only of urate, phospJiaie, oxalate^ and
carbonate of ammonia, together with salts. "j"

The ammonia, therefore, pf the salts contained in Guano, must
have yielded the nitrogen to th6se plants. Gluten is obtained
from corn ; vegetable albumen from certain juices, such as from
the expressed juice of the grape ; vegetable casein occurs in the
seeds of the leguminous plants ; but although all these have dif-
ferent names and properties, they are identical in composition
with the ordinary gluten.

It is then ammonia which yields nitrogen to the vegetable albu-
men, the principal azotised constituent of plants. Nitrogen is
not presented to wild plants in any other form capable af assimi-
lation. Ammonia, by its transformation, furnishes nitric acid to
the tobacco-plant, sunflower, 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

* The guano, which forms a stratum several feet in thickness upon the
surface of these islands, consists of the putrid excrements of innumerable
•ea fowl that remain on them during the breeding season. (See tb#
Chapter on Manures.)

t Boussingault, Ann. de Ch. et de Phys., Ixv., p. 3H)

FORM IN WHICH AMMONIA IS PRESENTED. 49

also subject to the influence of the direct rays of the sun ; an
nfluence necessary to effect the disengagement within their slem
and leaves of the oxygen which shall unite with the ammonia to
form nitric acid.

The urine of men and of carnivorous animals contains the
largest quantity of nitrogen, partly in the form of phosphates,
partly as urea. Urea is converted during putrefiiction into car-
bonate of ammonia, that is to say, it takes the form of the very
salt in rain-water. Human urine is the most powerful manure
for vegetables rich in nitrogen ; the urine of cattle, sheep, and
horses, contains less nitrogen ; but yet far more than the solid
excrements of these animals. In addition to urea, the urine of
herbivoKous animals contains hippuric acid, which is decomposed
during putrefiiction into benzoic acid, and ammonia. The latter
causes the formation of gluten, but the benzoic acid oflen remains
unchanged : for example, in tlie Anthoxanikum odoratum.

The solid excrements of men and of animals contain compara-
tively very little nitrogen, but this could not be otherwise. The
food taken by animals supports them only in so far as it offers to
the various organs elements for assimilation which they may
require for their increase or renewal. Corn, grass, hay, and all
plants, without exception, whether fresh or dried, contain highly
azotised substances. The quantity of food n quired by animals
for their nourishment diminishes or increases in the same propor-
tion as it contains more or less of the substances containing
nitrogen. A horse may be kept alive by feeding it with
potatoes, a food containing a very small quantity of nitrogen ;
but life thus supported is i\ gradual starvation ; the animal
increases neither in size nor strength, and sinks under every
exertion. The quantity of rice consumed by an Indian astonishes
the European ; but the fact that rice contains less nitrogen than
any other kind of grain at once explains the circumstance.

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 solid excrements of
these animals will be deprived of it in proportion to the perfect
digestion of the food, and can only contain it when mixed with
secretions from the liver and intestines. Under all rircumstan.
4

50 SOURCE AND ASSIMIL-\T10N OF NITROGEN.

ces, they must contain less nitrogen than the food. When,
therefore, a field is manured with animal excrements, a smaller
quantity of matter containing nitrogen is added to it than has
been taken from it in the form of grass, herbs, or seeds. There-
fore, it follows that the favorable activity of such manure cannot
be due to its nitrogen.

The liquid manure of animals must, on the other hand, be of
the highest value with respect to nitrogen : because it contains
all or nearly all the nitrogen originally present in the food con-
sumed. In order to comprehend more clearly the importance
of liquid excrements, it is necessary to consider the manner in
which they are formed.

It is well known that the body of an adult man, or of ah animal
in a state of health, remains constantly the same, and neither
diminishes nor increases in weight to any appreciable extent.
In youth the case ii different ; for an increase of the body is
occasioned. The same is the case in the artificial process of
fattening. The body of the old man, on the other hand, gra-
dually diminishes in size.

The quantity of nitrogen and of other constituents in the body
cannot therefore increase, although the animal always receives
in his food a considerable quantity of that element. From this
it follows, that the quantity of nitrogen expelled from the body
must be the same as that taken in the food by an animal in a
state of nature, freely exposed to exercise ; for if this were not
the case, the body must acquire a larger proportion of nitrogen,
which we know it does not.

When an individual is deprived of food and in the progress of
starvation, his body diminishes in weight, in Such a manner that
all parts, except the membranes and bones, participate in the
loss. By what means has the nitrogen of those tissues been
expelled from the system ?

The emaciation which occurs proves that during every moment
in the life of an animal, part of its structure loses its vitality, and
assumes the form of dead matter. This, after suffering certain
changes, is finally separated from the system by the organs of
secretion, namely, the skin, lungs, and kidneys. The daily losi
thus experienced is restored by food.

FORM IN WHICH AMMONIA IS PRESENTED. 51

The azotised constituents of the food are transformed into
blood, which then nourishes the animal by restoring its wasten
tissues to their original condition.

The uniform weight of an animal proves that a quan-
tity OF NITROGEN MUST HAVE BEEN EXPELLED FROM THE SYSTEM,
EXACTLY CORRESPONDING TO THE AMOUNT CONTAINED IN THE FOOD

CONSUMED. The compounds consisting of carbon and hydrogen,
derived from the waste matter, are separated by the lungs and
skin ; whilst those containing nitrogen are eliminated in the
urine. When the body increases in weight, a smaller quantity
of nitrogenous compounds must be separated by the urine ; a
diminution in weight indicates, on the other hand, a greater
separation of these compounds. These considerations prove that
the nitrogen extracted from the atmosphere by plants as food, is
again in a great measure returned in the urine of man and other
animals.

It is obvious that, by collecting both the solid and liquid excre-
ments of an animal fed upon the produce of a certain surface of
land, we are enabled to supply to it nearly the same quantity of
nitrogen as that contained in the original produce. Thus we
supply to the land a certain quantity of ammonia, in addition to
that which may be extracted from the atmosphere by the plants
growing upon it.

In a scientific point of view, it should be the care of the agri-
culturist so to employ all the substances containing a large pro-
portion of nitrogen, which his farm affords in the form of animal
excrements, that they shall serve as nutriment to his own plants.
This will not be the case unless those substances are properly
distributed upon his land. A heap of manure lying unemployed
upon his land would serve him no more than his 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.

Tacitus informs us that the surface of Germany was in his
time completely covered with impenetrable forests. But now
these no longer exist, and all their constituents have disappeared.
The carbon and nitrogen deposited in the soil in the form of
humus and ammonia have now returned to the atmosphere.

63 SOURCE AND ASSIMILATION OF NITROGEN.

All putrefying animal matters emit carbonic acid and ammonia
as long as nitrogen exists in them. In every stage of their putre-
faction an escape of ammonia 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
exhibited when a solid body moistened with an acid is brought
near it. This ammonia evolved from manure is imbibed by the
soil either in solution in water, or in the gaseous form, and plants
thus receive a larger supply of nitrogen than is afforded to them
by the atmosphere.*

But it is much less the quantity of ammonia yielded to a soil
by animal excrements, than the form in which it is presented by
them, that causes their great influence on its fertility. Wild
plants obtain more nitrogen from the atmosphere in the form of
ammonia than they require for their growth ; for the water
evaporated through their leaves and blossoms emits, after some
time, a putrid smell, a peculiarity possessed only by bodies con-
taining nitrogen. Cultivated plants receive the same quantity of
nitrogen from the atmosphere as trees, shrubs, and other wild

* " I filled a large retort," says Sir H. Davy, " capable of containing
three pints of water, with some hot fermenting manure, consisting prin-
cipally of the litter and dung of cattle ; and adapted a small receiver to
the retort, and connected the whole with a mercurial pneumatic appa-
ratus, so as to collect the condensible and elastic fluids which might rise
from tb«» dung. The receiver soon became lined with dew, and drops
began in a few hours to trickle down the sides of it. Elastic fluid like-
wise was generated ; in three days 35 cubical inches had been formed,
which, when analysed, were found to contain 21 cubical inches of car-
bonic acid ; the remainder was hydro-carbonate mixed with some azote,
probably no more than existed in the common air in the receiver. The
fluid matter collected in the receiver at the same time amounted to
nearly half an ounce. It had a saline taste, and a disagreeable smell,

nd contained some acetate and carbon^ate of ammonia.
" Finding such products given off" from fermenting litter, I introduced

he beak of another retort, filled with similar dung very hot at the
Vime, into the soil amongst the roots of some grass in the border of a
garden ; in less than a week a very distinct effect was produced on the
grass ; upon the spot exposed to the influence of the matter disengaged
in fermentation, it grew with more luxuriance than the grass in any
other part of the garden." — Works of Sir H. Davy, Edited by Dr. Johu
Davy, vol. viii., page 31

USE OF GYPSUM. 53

plants ; and this is quite sufficient for the purposes of agricuL
ture. Agriculture differs essentially from the cultivation of
forests, inasmuch as its principal object consists in the production
of THE CONSTITUENTS OF THE BLOOD ; whilst the object of forest
culture is confined principally to the production of carbon. But
the presence of ammonia alone does not suffice for the production
of the nitrogenous ingredients. Other conditions likewise are
quite essential. All the various means of culture are sub-
servient to these two main purposes. A part only of the car
bonate of ammonia conveyed by rain to the soil is received by
plants, because a certain quantity of it is volatilized with the
vapor of water ; only that portion of it can be assimilated which
sinks deeply into the soil, or which is conveyed directly to the
leaves by dew, or is absorbed from the air along with the
carbonic acid.

I^iquid animal excrements, such as the urine with which the
solid excrements are impregnated, contain only a small part of
their ammonia in the state of salts, that is, in a form in which it
has completely lost its volatility. The greatest part exists in the
form of carbonate of ammonia — a salt of great volatility. When
the ammonia is presented in the condition of a fixed salt, not the
smallest portion of it is lost to 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, in some degree,
upon its fixing in the soil the ammonia of the atmosphere, which
would otherwise be volatilized, with the water which evaporates.*

* I made the following experiment on a small g^arden plot. Beans and
peas were planted in the soil, after it had been well manured by mixing it
with fresh horse-dung. The whole surface of the plot was strewed with
gypsum to the depth of a line, and then covered so as to be protected from
the rain. In dry weather it was duly watered.

The plants soon appeared above grouiid and flourished with great luxuri-
ance. Before the commencement of the experiment, I had examined both
the soil and the gypsum, and found that both were quite free from the
smallest trace of carbonates. But on testing some of the gypsum taken
from the surface after the lapse of several weeks, I ascertained that the
greatest part of it had been converted into carbonate of lime. All th«
soil to the depth of half a foot now effervesced strongly on the addition of
acid.

84 SOURCE AND ASSIMILATION OF NITROGEN.

The carbonate of ammonia contained in rain-water is decomposed
by gypsum, in precisely the same manner 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 the carbonate of ammo-
nia 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 aromatics, which increase the
activity of the human stomach and intestines, and give a tone
to the whole system. But plants do not contain nerves : we
know of no substance capable of exciting them to intoxication
and madness, or of lulling them to sleep and repose. No sub-
stance can possibly cause their leaves to appropriate a greater
quantity of carbon from the atmosphere, when the other constitu-
ents required for the growth of the seeds, roots, and leaves, are
wanting. f The favorable action of small quantities of aromatics
upon man, when mixed with his food, is undeniable ; but aro-
matics 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, chloride of calcium, and of other salts
of lime, really consists in their giving a fixed condition to the
nitrogen, or ammonia, introduced to the soil. This nitrogen, is
indispensable for the nutrition of plants.

In order to form a conception of the effect of gypsum, it may
be sufl[icient to remark that 100 lbs. of burned gypsum fixes as

* 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 and re-
taining the ammoniacal salts. — Ed,

" I lixiviated some earth," says Spatzier, " and in the filtered solution,
after evaporation, I obtained an appreciable quantity of sulphate of ammo-
nia."— Erdmari's Journal, 1831, Bd II , s. 89.

f Schiibler states that white arsenic in small quantity exerts a beneficial
action upon vegetation — a fact proved by Lampadius, who manured whole
fields with this substance.

USE OF BURNED CLAY AS A MANURE. 55

much ammonia in the soil as 0250 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
furnish to a field 40 lbs. of gypsum, and if we suppose that the
tenth part of this enters into plants in the form of sulphate of
ammonia, we would actually supply nitrogen sufficient for 100
lbs. of hay, 50 lbs. of wheat, or 60 lbs. of clover.

Water is absolutely necessary to effect the decomposition of
the gypsum, on account of its difficult solubility (1 part of gyp-
sum requires 400 parts of water for solution), and also to assist
in the absorption of the sulphate of ammonia by the plants :
hence it happens, that the influence of gypsum is not observable
on dry fields and meadows ; wlii'e the gaseous carbonate of
ammonia formed by the decay of animal manures on such fields,
on the other hand, does not fail in producing a favorable effect.

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 well-known advantage derived by manuring fields with
burnt clay, and the fertility of ferruginous soils, may be ex-
plained in an equally simple manner. The favorable effects
produced by these causes have been ascribed to the great attrac-
tion for water exerted by dry clay and ferruginous earth ; but
common dry arable land possesses this property in as great a
degree ; and besides, what influence can be ascribed to a hun-
dred pounds of water spread over a field, in a condition in which
it cannot be made available either by the roots or leaves ? The
true cause is this : —

Peroxide of iron and alumina are distinguished from all other
metallic oxides by their power of forming solid compounds with

* The urine of the horse contains, according to Fourcroy and Vauquelin,
in lOO) parts.

Urea . . . 7 parts.

Hippurate of soda . 14 **

Salts and water . 979 "

1 000 parts. ( See Appendix. )

56 SOURCE AND ASSIMILATION OF NITROGEN.

ammonia. The precipitates obtained by the addition of ammonia
to salts of alumina or iron are true salts, in which the ammonia
is contained as a base. Minerals containing alumina or oxide
of iron also possess, in an eminent degree, the remarkable property
of attracting ammonia from the atmosphere and of retaining it.
Vauquelin, whilst engaged in the trial of a criminal case, dis-
covered that all rust of iron contains a certain quantity of
ammonia. Chevalier afterwards found that ammonia is a con-
stituent of all minerals containing iron ; that even hematite, a
mineral which is not at all porous, contains one per cent, of it.
Bouis showed also that the peculiar odor observed on moistening
minerals containing alumina, is partly owing to their exhaling
ammonia. Indeed, many kinds of gypsum and some varieties
of alumina, pipe-clay for extrnple, emit so much ammonia, when
moistened with caustic potash, even after they have been exposed
for two days, that reddened litmus paper held over them becomes
blue. Soils, therefore, containing oxides of iron, and burned
clay, must absorb ammonia, an action which is favored by their
porous condition ; they further prevent, by their chemical pro-
perties, the escape of the ammonia once absorbed. Such soils,
in fact, act precisely as a mineral acid would do, if extensively
spread over tl)eir surface.

The ammonia absorbed by the clay of 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 previ-
ously heated to redness. Charcoal absorbs ninety 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 seventy-two times its volume of this gas, after
having been completely dried under the air-pump. We have
here an easy and satisfactory means of explaining still further
the properties of humus, or wood in a decaying state. It is not
only a slow and constant source of carbonic acid, but it is also

CONCLUSION. 5?

a means by which the necessary nitrogen is conveyed to
plants.*

Nitrogen is found in lichens growing on basaltic rocks. Our
fields produce more of it than we have given them as manure,
and it exists in all kinds of soils and minerals which were never
in contact with organic substances. The nitrogen in these cases
could only have been extracted from the atmosphere.

We find this nitrogen in the atmosphere, in rain-water, and in
all kinds of soils, in the form of ammonia, as a product of the
decay and putrefaction of preceding generations of animals and
vegetables. We find likewise that the proportion of azotised
matters 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 than this,
that it is the ammonia of the atmosphere which furnishes nitro-
gen to plants. I

Carbonic acid, water, and ammonia, contain the elements
necessary for the support of animals and vegetables. The same
substances are the ultimate products of tiie chemical processes
of decay and putrefaction. All the innumerable products of
vitality resume, after death, the original form from which they
sprung.

Thus the destruction of an existing generation becomes the
means for the production of a new one, and death becomes the
source of life.

But it may be asked — Are the compounds now named the
only substances necessary- for the support of vegetable life ? This
question must be answered decidedly in the negative.

• When the extract of humus is evaporated with muriatic acid, a residue
is obtained which evolves ammonia by the addition of potash. When this
extract is subjected to distillation along with water, and the products of
distillation received into dilute muriatic acid, the latter is found to contain
muriate of ammonia. Humus contains carbonate of ammonia. — Wieg-
mann und Polstorfy Priesschrift, s. 53.

t We refer the reader to the Appendix for the part which nitric acid
takes in vegetation, and also for the origin of ammonia
4*

ON THE SOURCE OF SULPHUR.

CHAPTER VI.

On the Source of Sulphur.

Physiology teaches us that all the tissues of the body, such as
muscular fibre, cellular tissue, the organic substance of bones,
hair, skin, &c., are formed from the blood — the fluid which cir-
culates through every part of the organism.

The blood, from which all parts of the animal frame are pro-
duced, is itself furnished to animals by plants. For although
the carnivora subsist wholly on the flesh and blood of the herbi-
vora, they actually receive from the latter the component parts
of the plants upon which they were nourished.

Chemists have ascertained that sulphur is contained in the
two principal ingredients of blood, named by them fibrin and

ALBUMEN.

When fresh blood is agitated with a rod or stick, fibrin is
separated in the form of white elastic fibres. A similar separa-
tion of this ingredient takes place when blood is allowed to stand
for a certain time. The whole becomes coagulated into a sort of
jelly, which gradually contracts, and separates itself into a yellow-
ish-colored liquid, containing the serum or water of the blood, and
into a net- work of very fine threads of fibrin. The latter inclose
within them the coloring matter of the blood, just as a sponge
would do in similar circumstances.

The ALBUMEN is contained in the serum, and communicates to
that fluid the property of coagulating by heat, in a manner
similar to the white of an egg, which contains albumen as its
principal ingredient.

Fibrin, when removed from the circulation, is found to be per-
fectly insoluble in cold water. Albumen on the other hand, in
its natural condition, as it exists in serum or in the white of egg,
is soluble in water, and miscible with it in all proportions.

VEGETABLE CONSTITUENTS OF BLOOD. M

Casein, or cheese, the principal ingredient of milk, must also
be enumerated as a material used in the formation of blood.
Casein is generated in the animal economy, and is the only azo«
lised nutriment furnished by the mother to the young animal.

Now albumen, fibrin, and casein contain sulphur, a circum-
stance by which they are distinguished from all other component
parts of the animal body. This sulphur does not exist in the
form of an oxide, such as sulphuric acid or one of its salts. It
is^eTl' Known tliaV the albumen of eggs emits, during its putre-
faction, sulphuretted hydrogen gas ; and it is owing to this that
rotten eggs possess the property of blackening silver or other
metals with which they may be brought in contact. During the
putrefaction of fibrin and albumen, the same gas is likewise gene-
rated. There are many other ways by which we might prove
the presence of sulphur in these bodies.

From what source does the animal body derive these three fun-
damental components ? Unquestionably they are obtained from
the plants upon which the animals subsist : but in what form, and
in what condition, are they contained in plants ?

Rccerrt investigations of chemists have enabled us to answer
these questions with positive certainty. Plants contain, either
deposited in their roots or seeds, or dissolved in their juices,
variable quantities of compounds containing sulphur. In these
nitrogen is an invariable constituent. Two of the compounds
containing sulphur exist in the seeds of cereal plants, and in
those of leguminous vegetables, such as peas, lentils, and beans.
A third is always present in the juices of all plants; and it is
found in the greatest abundance in the juices of those which we
use for the purpose of the table.

A very exact inquiry into the properties and composition of
substances has produced a very remarkable result, namely, that
the sulphur compound dissolved in the juice of plants is, in re-
ality, identical with the albumen contained in the serum of
blood, and in the white of an egg ; that the sulphur compound in
the seeds of the cereals possesses the same properties and com-
position as the FIBRIN of blood; and that the nutritious constitu-
ent of peas, beans, ard lentils, is actually of the same nature and
composition as the casein of milk. Hence it follows that plants,

60 ON THE SOIJRCK OF SULPHUR.

and not animals, generate the constituents of blood containing
sulphur. When these are absent from the food given to an
animal, its blood cannot be formed. From this it also follows,
that vegetable food will be proportionally nutritious and fit to
sustain tlie vital processes of the animal body, according to the
amount of these ingredients contained within it.

There also exist certain families of plants, such as the Cruci-
ferse, which contain peculiar sulphur compounds much richer in
that element than the vegetable constituents of blood. The seeds
of black mustard, the horse-radish, garlic, onions, and scurvy-
grass, are particularly marked in this respect. From all of these
plants we obtain, by simple distillation with water, certain vola-
tile oils, differing from all other organic compounds not contain-
ing sulphur, by their peculiar, pungent, and disagreeable odor.

Those compounds containing sulphur are present in the seeds
of all plants, as well as in the plants themselves ; and as they
are particularly abundant in cultivated plants employed for
animal nutrition, it is quite obvious that a substance containing
sulphur is absolutely essential to the development of such com-
pounds, in order to supply to them their proper proportion of this
element.

It is also obvious, that although all other conditions for the
nourishment of plants be present, if the compound containing
sulphur be either wholly absent or deficient in quantity, the vege-
table constituents containing sulphur will either be not at all
formed, or they will be generated only in proportion to the quan-
tity of the above compound. The air cannot contain any sub-
stances in which sulphur is present, unless indeed we except
minute and scarcely appreciable traces of sulphuretted hydrogen.
The soil, therefore, must be the only means of furnishing the
sulphur so necessary to the growth of plants ; and we are
ignorant of any way by which it can be introduced except
through the roots.

The numerous analyses made of the water of mineral springs,
furnish us with a satisfactory explanation of the form in which
sulphur occurs in soils. The water of such springs is entirely
derived from the rain which falls upon the surface of the earth ;
the water percolating througl". the earth, dissolves all soluble

SUBSTANCES YIELDING SULPHUR. «1

materials which it may meet in its course. The substances
thus dissolved communicate to the water properties which are
not possessed by pure water. Water procured from springs or
wells is found to be very rarely deficient in soluble salts of sul-
phuric acid. The liquid obtained by lixiviating good soil from
garden or arable land also contains very appreciable quantities
of these salts.

The facts now detailed leave little doubt as to the source
whence plants obtain their sulphur. As far as our knowledge
extends, they receive their sulphur from the sulphates dissolved
in the water absorbed by their roots from the soil.

Ammoniacal salts, particularly sulphate of ammonia, are
rarely detected in spring water ; but this is owing to the con-
stant presence of supercarbonate of lime, Avhich effects their
decomposition, and allows the escape of ammonia during the
evaporation of the liquid for the purposes of analysis.

According to our view, sulphate of ammonia is of all com-
pounds containing sulphur the one most fitted for the assimilation
of that element. Sulphate of ammonia contains two elements,
both of which are equally necessary for the support of vegetable
life ; these are sulphur and nitrogen, and they form constituents
also of vegetable albumen, fibrin, and casein. But what is still
more worthy of observation, sulphate of ammonia, viewing it
according to the proportion of its elements, or what is termed its
empirical formula (SO ,, N H,,), may be considered as a com-
pound of water with equal equivalents of sulphur and nitrogen.
Thus, by the simple removal of the elements of water from this
compound, its sulphur and nitrogen might be enabled to pass over
into the composition of the plants.

The ingredients of plants containing sulphur are so composed
that one equivalent of sulphur exists for every 25 equivalents
of nitrogen. Hence it is obvious that much more ammonia
must be offered to plants than that contained in the form of sul-
phate of ammonia, if all the sulphur of the latter is to become a
constitueiit-of the organic ingredients alluded to.

This bears a complete analogy to the assimilation of the car-
bon and nitrogen furnished to plants in the form of carbonate of
ammonia. This salt may contain two equivalents of carbon to

ON THE SOURCE OF SULPHUR.

one equivalent of nitrogen. Hence it is necessary that the car-
bon of six equivalents of carbonic acid must at the same time be
taken up, and enter into combination with the nitrogen, in order
to produce the principal nitrogenous constituents which contain
one equivalent of nitrogen to eight equivalents of carbon.

The passage of sulphur derived from a sulphate into the com-
position of vegetable matter, necessarily indicates that the sul-
phate has been exposed to the action of the same causes as those
by which the decomposition of carbonic acid was effected in the
plant ; and, therefore, that the sulphuric acid has been decom-
posed into sulphur and oxygen, the former of which is assimi-
lated, whilst the latter is separated. If we suppose the sulphuric
acid to be presented in the form of sulphate of potash or soda, the
bases of these salts must be set at liberty after the decomposition
of their acid.

Now we actually find these bases in all cultivated, and eveh
in most wild plants. They are found either united to organic
acids, or, what is still more remarkable, they are found in union
with the vegetable compounds containing sulphur. The vege-
table casein of peas, beans, and other leguminous plants, is itself
insoluble in water; but it is very soluble in the form in which
it occurs in the plant. This solubility is due to the soda and
potash with which it is united. In like manner, the albumen
contained in the juices of plants is combined with an alkali ; and
we must suppose that vegetable fibrin, the insoluble ingredient of
cereal plants, must have originally been soluble, and have at-
tained its position in the seeds by the agency of alkalies.

The potash and soda of the alkaline sulphates which furnish to
plants their sulphur, remain, therefore, either in combination
with the ingredients containing that element, or they enter into
some new state of combination, or, finally, they are returned to
the soil.

Gypsum (sulphate of lime) is the most generally diffused sul-
phate. Being soluble, it may either pass directly into the plant,
or ii may be decomposed by the carbonate of ammonia existing
in rain-water, when its sulphur will pass into the plant in the
form of sulphate of ammonia.

A solution of gypsum containing common salt or chloride

MIXTURE OF GYPSUM AND OF SALT. 6%

of potassium, such as sea-water, and the water of most springs,
may be viewed as a mixture of an alkaline sulphate with
chloride of calcium. From this it must be obvious, that when
we furnish to a plant at the same time both gypsum and common
salt (chloride of sodium), we actually furnish by such a solution
the same materials that we would do if we supplied a mixture
of sulphate of soda and chloride of calcium. In order to form
the constituents containing sulphur, that element and the alkali
must be retained by the plant, while the chlorine and calcium
will be expelled by the roots*

We know that this process actually does take place in the
case of marine plants. The soda or potash is obtained from
common salt or chloride of potassium, which suffers decomposi-
tion by the presence of sulphate of lime or sulphate of magnesia.
It is necessary to suppose that this process also occurs with the
cereal and all other plants, the ashes of which are destitute of
lime, and the sulphur of which has been supplied in the form of
gypsum. Thus we are enabled to explain the use of common
salt as a manure ; it enables the plant, for which this manure is
useful, to extract its sulphur from the soil in which it existed in
the form of sulphate of lime.

64 OF THE INORGANIC CONSTITUENTS OF PLANTS.

CHAPTER VII.

Of the Inorganic Constituents of Plants.*

Carbonic acid, water, ammonia, and sulphates, 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 formation of certain organs destined
for special functions peculiar to each family of plants. Plants
obtain these substances, as they do the sulphur they contain,
from inorganic nature. In the ashes left after the incineration
of plants, the same substances are found, although in a changed
condition.

Many of the inorganic constituents vary according to the soil
in which the plants grow, but a certain number of them are in-
dispensable to their development. 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
assimilation.

Alkaline and earthy phosphates form invariable constituents
of the seeds of all kinds of grasses, of beans, peas, and lentils.

These salts are introduced into bread along with the flour, and

* " Many authors," says Saussure, " consider that the mineral ingredi-
ents of plants are merely accidentally present, and are not at all necessary
to their existence, because the quantity of such substances is exceedingly
small. This opinion may be true as far as regards those matters which
are not always found in plants of the same kind ; but there is certainly no
evidence of its truth with those invariably present. Their small quantity
does not indicate their inutility. The phosphate of lime existing in the
animal body does not amount to the fifth part of its weight, yet no one
doubts that this salt is necessary for the formation of its bones. I have
detected the same compound in the ashes of all plants submitted to exami-
nation, and we have no right to suppose that they could exist without it,**
(Be SaussurCy p. 241.)

IMPORTANCE OF ALKALINE BASES. 65

into beer along with barley. The bran of flour contains a large
quantity of ammoniacal phosphate of magnesia. This salt forms
large crystalline concretions, often amounting to several pounds
in weight, in the ccecum 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 combina-
tion with bases, such as potash, soda, lime, or magnesia ; plants
containing free organic acids are few in number. These bases
evidently 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 quantity of acid contained in its juice is
less when it is ripe than when unripe ; and the bases, under the
same circumstances, are found to vary in a similar manner.
Such constituents exist in the smallest quantity 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 greatest in those
organs whose office it is to prepare substances conveyed to them
for assimilation by other parts. The leaves contain more inor-
ganic matters than the branches, and the branches more than the
stem (Sauss[jre). The potatoe plant contains more potash before
blossoming than after it (Mollerat).

The acids found in the different families of plants are of vari-
ous kinds ; it cannot be supposed that their presence and peculi-
arities are the result of accident. The fumaric and oxalic acids
in the lichens, the kinic acid in the RubiacecB, the rocellic acid
in the Rocella tinctoria, the tartaric acid in grapes, and the nu-
merous other organic acids, must serve some end in vegetable
life. But if these acids constantly exist in vegetables, and are
necessary to their life, which is incontestable, it is equally cer-
tain that sonrie alkaline base is also indispensable, in order to enter
into combination with the acids ; for these are always found in
the state of neutral or acid salts. All plants yield by incineration
ashes containing carbonic acid ; all, therefore, must contain salts
of an organic acid.*

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

«6 OF THE INORGANIC CONSTITUENTS OF PLANTS.

Now, as we know the capacity of saturation of organic acids
to be unchanging, it follows that the c uantity of the bases united
with them cannot vary ; and for this reason the latter substances
ought to be considered with the strictest attention, both by the
agriculturist and 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 what-
ever soil it grows, must contain an invariable quantity of alkaline
bases. Culture alone will be able to cause a deviation.

In order to understand this subject clearly, it will be necessary
to bear in mind that any one of many 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 exist-
ence in one plant of a particular alkali which may be absent in
others of the same species. If this inference 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 the acid in a given plant must consequently be a
constant quantity, and therefore the amount of oxygen contained
in them must remain unchanged under all circumstances and on
whatever soil they grow.*

* When sulphuric acid is placed in contact with potash, soda, lime, or
magnesia, the properties both of the acid and of the alkali disappear, and
if the proportions have been just, the compound thus produced is a neutral
sulphate of these bases.

100 parts of sulphuric acid require for neutralization very different quanti-
ties of the above bases; thus, to effect this purpose, it is necessary to em-
ploy 118 parts of potash, 7S parts of soda, 71 "2 parts of lime, and 51 "6 parts
of magnesia.

In order to produce a neutral nitrate with 118 parts of potash (the quan-
tity necessary to saturate 100 parts of sulphuric acid), we must employ 135
parts of nitric acid. Now, when we examine how much soda, lime, or
magnesia is required to saturate the same quantity of nitric acid (135 parts)
it is found that complete saturation is effected by 7S of soda, 7r2 of lime,
51 "6 of magnesia, or exactly the same quantities as in the case of sulphuric
acid. It is quite indifferent what acids we use to neutralize their bases, or
how much the numbers obtained may differ from those now stated ; still
the relative proportion remains invariable. If for the saturation of anjf

INVARIABLE QUANTITY OF ALKALINE BASES. 6'

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 carbon-
ates, the quantity of which can be easily ascertained. The
bases contained in the bark do not any longer belong to the vital
organism of the plant.

It has been distinctly shown, by the analyses of De Saussure
and Berthicr, that the nature of a soil exercises a decided influ-
ence 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,

particular acid 51 "6 parts of magnesia have been used, we may be perfectly
certain that the same quantity of this acid will be exactly neutralized by
78 parts of soda.

We have now to state the causes which occasion this unequal power of
these metallic oxides to neutralize acids We have also to expLiin why, to
produce the same efiect, it is necessary to employ a smaller quantity of soda,
and only one half the quantity of magnesia that we would use of potash,
and still that the relative quantities are constant with all acids,

A knowledge of the composition of the bases has afforded us a very sijn
pie explanation of these causes. All the bases now mentioned contain
oxygen combined with a metal ; and their capacity of saturation depends
upon the quantity of oxygen contained within them.

Although the absolute quantities of the above bases are so very different,
they all contain the same quantities of oxygen.

Oxygen contained.
100 Sulphuric Acid neutralize 118 Potash = 20
100 " " " 78 Soda = 20

100 " " " 71-2 Lime = 20

100 " " " 51-6 Magnesia = 20

Now, if we neutralize 100 parts of sulphuric acid with potash and soda,
or with potash, soda, and lime, or with potash, soda, lime, and magnesia,
the sulphuric acid unites with quantities of two, three, or four bases exactly
corresponding to their united quantity of oxygen. This may be represent-
ed in the following table : —

100 parts sulphuric acid neutralize < Sodium" \ '^^ P'^rts oxygen.

C Potassium ^

100 " " " " < Sodium V 20 " oxygen.

f Calcium )

(Potassium ^

iM;

gnesium

flS OF THE INORGANIC CONSTITUENTS OF PLANTS

whilst it was absent from the ashes of a tree of the same species
from Mont La Salle, and that the proportion of lime and potash
was also very different.

Hence it has been concluded (erroneously, I believe), that the
presence of bases exercises no particular 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
m both cases the same.

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

Carbonate of Potash . 3*60 Quantity of oxygen in the Potash . 0*415

Lime . 4G-34 " '" " Lime . 7-327

" Magnesia 677 " " " Magnesia. 1-2G5

Sum of the carbonates 50 71 Sum of the oxygen in the bases 9"007

100 parts of the ashes of the pine from Mont La Salle con-
tained— *

Carbonate of Potash . 7*36 Quantity of oxygen in the Potash . 0-85
Lime . 51-19 " " " Lime . 8-10

" Magnesia 00 00

Sum of the carbonates 5S5.3 Sum of the oxygen in the bases 8-0-">

The numbers 9-007 and 8-95 approach each other ns 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 ha<l not in view.

Let us now compare Berthier's analyses of the ashes of two
fir-trees, one of which grew in Norway, the other in Allevard
{departement de risdre). One contained 50, the other 25 per

* 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 quantity
of wood froiK Mont La Salle yielded 11-28 parts.

INVARIABLE QUANTITY OF ALKALINE BASES. 89

cent of soluble salts. A greater difference in the proportion of
the alkaline bases could scarcely exist between two totally dif-
ferent plants, and yet even here the quantity of oxygen in the
bases of both was the same.

loo 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 "57 parts must be oxygen
Lime . . 29'6 " 8-36 " "

Magnesia . 3-3 *« 1-26 " •*

49-7 13-19

Only part of the potash and soda in these ashes was in com-
bination with organic acids ; the remainder was in the form of
sulphates, phosphates, and chlorides. One hundred parts of
the ashes contain 0*797 sulphuric acid, 3*12 phosphoric acid,
and 0*077 hydrochloric acid, which together neutralize a quan-
tity of base containing 0*53 oxygen. This number, therefore,
must be subtracted from 13*19. The remainder, 12*66, indi-
cates the quantity of oxygen in the alkaline bases, combined
with organic acids in the firwood of Allevard.

The firwood of Norway contained in 100 parts, —

Potash . . 14*1 of which 24 parts would be oxygen.

Soda . . 20-7 " 5-3

Lime . . 13G " 382

Magnesia . 4*35 " I'GO

52-75 13-21

And if we subtract from 13*21 the quantity of oxygen of the
bases in combination with sulphuric and phosphoric acid, viz.,
0*79, 12*42 parts remain as the amount of oxygen contained in
the bases which were in combination with organic acids.

These remarkable approximations cannot be accidental ; and
if future investigations confirm them in other kinds of plants, no
other explanation than that already given can be adopted.

It is not known in what form manganese, and oxide of iron,
are contained in plants ; but we are certain that potash, soda,

70 OF THE INORGANIC CONSTITUENTS OF PLANTS.

and magnesia, can be extracted by means of water 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, tlie acid and potash never exist in the form of the
neutral oxalate or quadroxalate, but always as a binoxalate, on
whatever soil they may grow. The potash in grapes is always
found as an acid salt, viz., cream of tartar (bitartrate of potash),
and never in the form of a neutral compound. As these acidg
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 tho fruits and seeds, and also on many other
functions, of tlie nature of which we are at present ignorant.
The quantity of alkaline bases existing in a plant also depefids
evidently on this circumstance of their existing only in the form
of salts of certain acids, — for the capacity of saturation of an acid
is constant.

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 im-
portance to vegetable physiology, and would decide whether the
facts above mentioned are the results of an unchanging law for
each family of plants, and whether an invariable number can be
found to express the quantity of oxygen which each species of
plant contains in the bases united with organic acids. In all pro-
bability 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 sufficient quantity in the soil,
other alkaline bases, of equal value, 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 planta

SUBSTITUTION OF ALKALINE BASES. 71

grown from the seeds of this contain only salts of potash, with
mere traces of muriate of soda.* (Cadet.)

The existence of vegetable alkalies in combination with organic
acids gives great weight to the opinion that alkaline bases in
general are connected with the 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 extending towards the light, while mere traces 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, Idnic acid is found ; but the quantity of quinina, cin-
chonina, and lime contained in them is most variable. From the
fixed bases in the products of incineration, however, we may esti-
mate 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
different quantities of narcotina, morphia, codeia, &c., the quan-
tity of one of these alkaloids diminishing on the increase of the
others. Thus the smallest quantity of morphia is accompanied
by a maximum of narcotina. Not a trace of meconic acidf can
be discovered in many kinds of opium, but there is not on this

* " We planted," says Wiegmann and Polstorf, " several plants in a
flower-pot filled with common earth iVom the garden, and watered them
with a weak solution of chloride of potassium, having previously ascer-
tained that the earth contained mere traces of metallic chlorides. Sub-
jected to this treatment, the plants flourished very luxuriantly, so much
so that they completely covered the flower-pot, stretching far over its
sides. We now transplanted them into the open soil, and did not supply
them any longer with chloride of potassium ; but, in the following year,
they shrunk and died during the period of blossoming. It follows, from
the experiments which we have detailed, that both kinds of plants re-
quired metallic chlorides for their proper nourishment, but that it is quiU
indifferent whether the chlorine be united with sodium or potassium."
{Preischrift iiber die anorganischen Bestandtheile der Pflanzen.)

t Robiquet did not obtain a trace of meconate of lime from 309 lb?
of opium, whilst in other kinds the quantity was very considerabU
{Ann. de Chim , liii. , p 425)

72 OF THE INORGANIC CONSTITUENTS OF PLANTS.

account an absence of acid, for the meconic is here replaced by
sulphuric acid. Here, also, we have an example of what has
been before stated ; for in those kinds of opium where both these
acids exist, they are always found to bear a certain relative pro-
portion to one another.

Now if it be found, as appears to be the case in the juice of
poppies, that an organic acid may be replaced by an inorganic
without impeding the growth of a plant, we must admit the pro-
bability of this substitution 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 will not show themselves so frequently in
cultivated plants, because they are subjected to special external
conditions, for the purpose of the production of particular con-
stituents or of particular organs.

By sprinkling with the juice of the Phytolacca dexandra, the
soil in which a white hyacintli is growing in a state of blossom,
its white blossoms assume in one or two hours a red color, which
again disappears after a few days under the influence of sunshine,
and they become white and colorless as before.* The juice in
this case evidently enters into all parts of the plant, without
being at all changed in its chemical nature, or without its
presence being apparently either necessary or injurious. But
this condition is not permanent, and when the blossoms have
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 nutrition 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 potassium, nitre, or nitrate of
strontia ; they will enter into the difl^erent parts of the plant, just
as the colored juice mentioned above, and will be found in its
ashes if it should be burnt at this period. Their presence is

• Biot, in the Comptes rendus des Stances de I'Acad^mie dea Scieiico^
ft Paris, premier Sfemestre, 1837, p. 12.

EXCREMExNTS OF PLANTS. 73

merely accidental ; but this does not furnish ground for any con-
clusion against the necessity of the presence of other bases in
plants. The experiments of Macaire-Princep Jiave shown, that
plants made to vegetate with their roots in a weak solution of
acetate of lead, and then in rain-water, yield to the latter all the
salt of lead which they had previously absorbed. They return,
therefore, to the soil all matters 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 separated by the roots and
removed further from them by every shower of rain that falls
upon the soil, so that at last not a trace of it is to be found in the
plant. (Daubeny.) Let us consider the composition of the
ashes of the two fir-trees above mentioned as analysed by an
acute and most accurate chemist. One of these grew in Nor-
way, on a soil of invariable composition, but to which soluble
salts, and particularly common salt, were conveyed in great
quantity l)y rain-water. How did it happen that its ashes con-
tained no appreciable trace of salt, although we are certain that
lis 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 referred 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 of alkaline earths ; for
when these substances are totally wanting its growth will be ar-
rested, 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 unequal quantities of alkaline
bases, and we shall find that one of these may grow luxuriantly
in several soils upon which the other is scarcely able to vegetate. «
For example, 10,000 parts of oak-wood yield 250 parts of ashes,

74 OF THE INORGANIC CONSTITUENTS OF PLANTS.

the same quantity of fir-wood only 83, of lime-wood 500, of rye
440, and of the herb of the potatoe 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 lime-tree, because the bases
necessary to bring it to complete maturity exist there in suffi-
cient quantity. The accuracy of these conclusions, so highly
important to agriculture and to the cultivation of forests, can be
proved by the most evident facts.

All kinds of grasses, and the Equisetacc(2, for example, con-
tain 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, if it be again conveyed to them as manure in the form
of putrefying straw. But this is not the case in a meadow, and
hence we never find a luxuriant crop of grass f on sandy and cal-
careous soils containing little potash, evidently because one of the
cor.stituents 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 large quan-
tity of potash they contain. The potash abstracted by the
plants is restored during the annual irrigation. The amount of
alkalies contained in the soil itself is very great in com-
parison with the quantity removed by plants, although not
inexhaustible.

A harvest of grain is obtained every thirty or forty years
from the soil of the Luneburg heath by strewing it with the
ashes of the heath-plants {Erica vulgaris) growing upon it.
These plants, during the long period just mentioned, collect the
potash and soda contained in the soil and conveyed to them by
rain-water ; and it is by means of these alkalies that oats, barley,
and rye, to which they are indispensable, are enabled to grow on
this sandy heath.

* Berthier, Annales de Chimie et de Physique, t. xxx., p, 248.

f It would be of importance to examine what alkalies are contained in

the ashes of the sea-shore plants which grow in the humid hollows of

*down8, and especially those of the millet-grass If potash is not found io

them, it must certainly be replaced by soda, as in the Salsota, or by lime,

M in the Plttmbaginea.

REPIACEMENT OF EXHAUSTED ALKALIES. "S

The woodcutters in the vicinity of Heidelberg have the privi-
lege 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 indispen-
sable for the growth of the grain. The soil itself upon which
the oaks grow in this district consists of sandstone ; and although
the trees find in it a quantity of alkaline earths sufficient for
their own sustenance, yet in its ordinary condition it is incapable
of producing cereal crops.

The most decisive proof of the use of strong manure was ob-
tained at Bingen (a town on the Rhine), where the produce and
development of vines were highly increased by manuring them
with such nitrogenous manures as shavings of horn, &c. ; but
after some years the formation of the wood and leaves decreased
to the great loss of the proprietor, to such a degree that he has
long had cause to regret his departure from the usual methods,
ascertained by long experience to be the best. 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 re-
mained for the future crops, his manure not having contained
any potash.

There are vineyards on the Rhine, the plants of which are
above a hundred years old, and all of these have been cultivated
by manuring them with cow-dung, a manure containing a large
proportion of alkaline ingredients, although very little nitrogen.
All the alkalies, in fact, contained in the food consumed by a
cow are again immediately discharged in the liquid excrements.

The leaves and small branches of trees contain the greatest
quantity of ashes and of alkalies ; and the quantity of them annu-
ally removed from a wood, for the purpose of being employed as
litter,* contain much more of the alkalies than all the old wood

* [This refers to a custom some time since very prevalent in Germany,
although now discontinued. The leaves and small twigs of trees were
gleaned from the forests by poor people, for the purpose of being used af
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.]

76 OF THE INORGANIC CONSTITUENTS OF PLANTS.

cut down. The bark and foliage of oaks, for example, contain
from 6 to 9 per cent, of alkalies, the needles of firs and pines, 8
per ceLt.

With every 2650 lbs. of firwood yearly removed from an acre
of forest, only 7 or 8 lbs. of alkalies are abstracted from the soil,
calculating the ashes at 0.83 per cent. The leaves, however,
cover the soil, and being very rich in alkalies, in comparison
with the wood, retain those alkalies on the surface, which would
otherwise so easily penetrate with the rain through the sandy
soil. By their decay an abundant provision of alkalies is sup-
plied to the roots of the trees, and a fresh supply is rendered
unnecessary.

The ashes of the tobacco plant, of the vine, of peas, and of
clover, contain a large quantity of lime. Such plants do not
flourish on soils devoid of lime. By the addition of salts of lime
lo such soils, they become fitted for the growth of these plants ;
for we have every reason to believe that their development es-
sentially depends upon the presence of lime. Tiie presence of
magnesia is equally essential, there being many plants, such as
the different varieties of beet and potatoes, from which it is never
absent.

The supposition that alkalies, metallic oxides, or inorganic mat-
ter in general, are produced by plants, is entirely refuted by
these well-authenticated facts.

It is thought very remarkable, that the plants of the grass
tribe, fitted for the food of man, follow him like the domestic
animals. But saline plants seek the sea-shore or saline springs,
and the Chenopodium the dunghill, from similar causes. Saline
plants require common salt, and the plants growing only on dung-
hills need ammonia and nitrates, and they are attracted to places
where 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 re-
quire for their maturity. And hence, these plants grow only in
a soil where these three constituents are found combined, and no
soil is richer in them than those where men and animals dwell
together ; where the urine and excrements of these are found

NECESSITY OF CERTAIN COiNDITIONS FOR NUTRITION. 77

com plants appear, because their seeds cannot attain maturity
unless supplied with the constituents of those matters.

When we find sea plants near our salt-works, several hundred
miles distant from the sea, we know that their seeds have been
carried there in a very natural manner, namely, by wind or by
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 gradu-
ating-house at Nidda (a village 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 car-
bonic acid and lime, that the walls of the graduating-house are
covered with stalactites. Hence the eggs conveyed to this place,
by whatever cause, do not find the conditions necessary for their
development, although they did so in the former place.

How much more wonderful and inexplicable does it appear,
that bodies, remaining fixed in the strong heat of a fire, have un-
der certain conditions the property of volatilizing and, at ordinary
temperatures, of passing into a state, of which we cannot say
whether they have really assumed the form of a gas or are dis-
solved in one ! Steam or vapors in general have a very singu-
lar 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 substances dissolved in it,
although they do not of themselves possess that property.

Boracic acid is a perfectly fixed substance ; it suffers no
change of weight appreciable by the most delicate balance, when
exposed to a white heat, and therefore it is not volatile. Yet its
solution in water cannot be evaporated by the gentlest heat, with-
out 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 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; but neverthe.

78 OF THE INORGANIC CONSTITUENTS OF PLANTS.

less the many hundred tons annually brought from Italy as an
article of commerce, are procured by the uninterrupted accu-
mulation of this apparently inappreciable quantity. The hot
steam issuing from the interior of the earth, passes through cold
water in the lagoons of Castel Nuovo and Cherchiago ; in this
way the boracic acid is gradually accumulated, till at last it may
be obtained in crystals by the evaporation of the water. It is
evident, from the temperature of the steam, that it must have
come out of depths in which human beings and animals never
could have lived, and yet it is very remarkable and highly
important that ammonia is never absent from it. In the large
works in Liverpool, where natural boracic acid is converted into
borax, many hundred pounds of sulphate of ammonia are obtained
at the same time.

This ammonia has not been produced by the animai or>
ganism, but existed before the creation of human beings,
being a part, a primary constituent, of the globe itself.

The experiments instituted under Lavoisier's guidance by the
Direction des Poudrcs et SalpHres, 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 dis-
tance of from 20 to 30 miles from the sea. But it does not
require a storm to cause the volatilization of the salt, for the air
hanging over the sea always contains enough of this substance
to render turbid a solution of nitrate of silver, 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 potas-
sium, magnesia, and the remaining constituents of the sea-water,
will be conveyed by wind to the land.

This volatilization is a source of considerable loss in salt-
works, especially where the proportion of salt in the water is
small. This has been completely 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 evaporat-
ing houses, distant about 1200 paces from each other, and found

INORGANIC ORIGIN OF AMMONIA.

.n the morning, after the drying of the dew, that the glass was
covered with crystals of salt on one or the other side, according
to the direction of the wind.

By the continual evaporation of the sea, its salts* are spread
over the whole surface of the earth ; and being subsequently
carried down by the rain, furnish to vegetation those salts nece*.
sary to its existence. This is the origin of the salts found in the
ashes of plants, in those cases where the soil could not have
yielded them.

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 con-
fined 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 tliis proportion appears, it is quite sufficient to supply
the whole of the present generation of living beings with car-
bon for thousands of years, even if it were not renewed. Sea-
water contains i^^Iqq of its weight of carbonate of lime ; and
t'lis quantity, although scarcely appreciable in a pound, is the

* According to Marcet, sea- water contains in 1000 parts,
26-660 Chloride of Sodium.
4-660 Sulphate of Soda.
1"232 Chloride of Potassium.
5-152 Chloride of Magnesium.
1*5 Sulphate of Lime.

39-201
According to 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.
1-31 Chloride of Potassium
1-20 Sulphate of Lime.
In addition to these constituents, it also contains inappreciable quanti-
ties of carbonate of lime, magnesia, iron, manganese, phosphate of iime,
iodides, and bromides, and organic matter, together with ammonia and
carbonic acid. — Liebig's Annalen der Cherme. Bd. xxxvii., s. 3.

M OF THE INORGANIC CONSTITUENTS OF PLANTS.

source from which myriads of marine mollusca and corals are
supplied with materials for their habitations.

Whilst the air contains only from 4 to 6 ten-thousandth parti
of its volume of carbonic acid, sea-water contains 100 times
more (10,000 volumes of sea-water contain 620 volumes of car-
bonic acid — Laurent, Bouillon-Lagrange). Ammonia* is also
found in this water ; so that the same conditions which sustain
living beings on the land are combined in this medium, in which
a whole world of other plants and animals exist.

The roots of plants are constantly engaged in collecting from
the rain those alkalies which formed part of the sea-water, and
also those of the water of the springs penetrating the soil. With-
out alkalies and alkaline bases most plants could not exist, and
without plants the alkalies would disappear gradually from the
surface of the earih.

When it is considered that sea- water contains less ihan one-
millionth of its own weight of iodine, and that all combinations
of iodine with the metallic bases of alkalies are highly soluble
in water, some provision must necessarily be supposed to exist
in the organization of sea- weed and the different kinds of Fuci,
by which they are enabled during their life to extract iodine in
the form of a soluble salt from sea-water, and to assimilate it in
such a manner, that it is not again restored to tlie surrounding
medium. These plants are collectors of iodine, just as land
plants are of alkalies ; and they yield us this element in quanti-
ties such as we could not otherwise obtain from the water without
the evaporation of whole seas.

We take it for granted, that the sea plants require metallic
iodides for their growth, and that their existence is dependent on
the presence of those substances. With equal justice, then, we
conclude, that the alkalies and alkaline earths always found in
the ashes of land plants, are likewise necessary for their deve-
lopment.

* When the solid saline residue obtained by the evaporation of sea
water is lieated in a retort to redness, a sublimate of sal-ammoniac \f
obtained. — Marcet.

DISINTEGRATION OF ROCKS.

CHAPTER VIII.

On the Formation of Arable Land.

The hardest rocks and stones gradually lose their coherence
when exposed to the influence of certain agencies. Soils con-
sist of the debris of rocks which have suffered this change.

The disintegration of minerals and rocks is effected partly by
mechanical, and partly by chemical means. It has been re-
marked in all the mountainous districts of perpetual snow, that
the most refractory rocks crumble into fragments,* which are
either rounded by the action of glaciers, or are thoroughly pul-
verized into dust. The rivers and streams arising out of the
glaciers are rendered turbid with this mineral debris which they
deposit on reaching the plains and valleys ; thus fertile soils are
formed.

" As often as I have seen beds of mud, sand, and shingle,
accumulated to the thickness of many thousand feet, I have felt
inclined to exclaim, that causes such as the present rivers and
the present beaches could never have ground down such masses.
But, on the other hand, when listening to the rattling noise of
these torrents, and calling to mind that whole races of animals
have passed away from the surface of the globe, during the
period throughout which, night and day, these stones have gone
rattling onwards in their course, I have thought to myself. Can
any mountains, any continent, withstand such waste ?" f

* " I frequently observed, both in Terra del Fuego and within the
Andes, that where the rock was covered during the greater part of the
year with snow, it was shivered in a very extraordinary manner into small
angular fragments. Scoresby has observed the same fact in Spitzhergen ;
he says : ' The invariably broken state of the rocks appeared to have been
the effects of frost.' " — Darwin's JVat. Hist, of the Voyage of the Beagle,
p. 388.

t Darwin, Nat. Hist, of the Voyage of the Beagle, p. 386
5*

FORMATION OF SOILS.

In addition to these mechanical causes of waste, we have to
consider tlie influence exerted by chemical forces in eflfecting the
disintegration of rocks, such as the action of the oxygen and
carbonic acid of the air, as well as that of water, upon their
constituent parts. Whilst we apply the term waste to the
effects produced by mechanical agencies, we shall confine the
term disintegration to the effects produced by chemical forces.
The latter causes may be very gradual in their operation, not
being limited in regard to time. Hence we cannot refuse to
acknowledge the existence of their action, even though the effect
produced may not be sensible during the life of an individual.

Many years are necessary before the polished surface of an
exposed fragment of granite loses its polish ; but in process
of time this is effected, and the large fragment falls to pieces
under the influence exerted upon its constituents by the chemi-
cal forces.

The action of water is so much connected with that of oxygen
and of carbonic acid, that it is scarcely possible to consider their
effects apart.

Many kinds of rocks, such as basalt and clay-slate, contain as
an ingredient protoxide of iron. This oxide has a great tendency
to absorb oxygen from the air, becoming the higher oxide known
as peroxide of iron. This property is especially apparent in our
rich ferruginous soils. The surface of such soils to a certain
depth is of a red or brownish-red color, an indication that it con-
tains peroxide of iron ; whilst the black or brownish-black color
of the subsoil indicates the presence of tlie protoxide of the same
metal. It often happens that the subsoil is thrown upon the sur-
face in the course of subsoil-ploughing, and the consequence on
such soils is, that their fertility is destroyed for a certain number
of years. The injury thus received continues until all the sur-
face-soil again becomes red, that is, until all the protoxide of
iron is converted into the peroxide.

It is known that a crystallized salt of iron loses its coherence
on exposure to air, and crumbles into a powder by the absorption
of oxygen. In a similar manner the disintegration of most
minerals is effected, for their ingredients are susceptible of en-
tering into union with oxygen. In consequence of the formation

PROPERTIES OF SILICA.

of new compounds, the coherence of the original body is
destroyed. If the minerals contain metallic sulphurets, such
as the pyrites in granite, these are gradually converted into
sulphates.

Most kinds of rocks, such as felspar, basalt, clay-slate, por-
phyry, and the numerous members of the limestone formation,
consist of compounds of silica, with alumina, lime, potash, soda,
iron, and protoxide of manganese.

Before we can properly comprehend the action of water and
of carbonic acid upon minerals, it is necessary to recollect the
properties of silica and of its compounds with alkaline bases.

Quartz forms a very pure variety of silica, and, in this condi-
tion, it is quite insoluble both in cold and in hot water, is with-
out taste, and does not exert any action on vegetable colors.
The principal property of silica in this state is, that it unites with
alkalies, forming saline compounds, which are termed silicates.
Window and plate glass consist of mixtures of silicates of the
alkaline bases, potash, soda, and lime. In such compounds the
alkali is generally completely neutralized. The property of
neutralizing metallic oxides and alkalies belongs only to acids,
and it is owing to this that silica has received the name of silicic
acid.

Silica is a very feeble acid, for we have already mentioned
that, in its crystallized form, it is destitute both of taste and of
solubility in water ; but t dissolves when finely pulverized and
lK)iled for a long time in alkaline leys.

We may easily obtain compounds of silica with potash and
soda, by melting it either with a pure alkali, or with an alkaline
carbonate. By this treatment white glasses are obtained, differ-
ing in properties according to their amount of soluble ingre-
dients. When llie glass contains 70 per cent, of silica and 30
per cent, of potash or soda, it becomes soluble in boiling water.
Its solution may be spread over a surface of wood or of iron, and
then dries into a vitreous substance, which has received the
name of soluble glass. When there is a smaller proportion of
alkali than the above quantity, or, in other words, when there is
a larger proportion of silica, the resulting glass diminishes 4||
solubility in a greater or less degree. ,. ..-v

B^ I'ORMATION OF SOILS.

All silicates soluble in water are decomposed by acids. If the
solution of the silicate contains silica corresponding to more
than -^Q- the weight of the water, the addition of an acid causes
the formation of a precipitate of a very gelatinous appearance.
This precipitate, being a compound of silica with water, is
termed the hydrate of silica. But, if the solution contains less
silica than the above proportion, no precipitate is formed on the
addition of an acid, the whole remaining perfectly clear. This
circumstance proves that silica, in the state in which it is preci-
pitated by an acid, possesses a certain degree of solubility in
pure water. Indeed, by washing with water the gelatinous pre-
cipitate of silica formerly alluded to, its volume diminishes, and
silica may be detected in solutio:^ by evaporating the wate»
which has passed through.

From these facts we perceive, that silica possesses two distirt •
chemical characters. In the form in which it is separated fiorr*
a silicate, it possesses quite different properties from those whic^
it has when in the state of sand, quartz, or rock crystal. Whei*
sufficient water is present during its separation from a base, U
effect its solution, the whole remains dissolved ; in certaip
conditions, silica is more soluble in water than gypsum.

On drying, silica loses completely its solubility in watrs
The solution of silica in acids acquires, at a certain degree o?
concentration after cooling, such a gelatinous consistence tha'*
the vessel containing it may be turned upside down withoiM
spilling a drop of the transparent jelly. By drying it stiR
further, the water which retained it in the gelatinous condition
escapes along with that which had served to hold it in solutior .
When the water has been onco removed in this way, the silici^
is no longer soluble in water. But, although it has thus lost its
solubility, it does not acquire all the properties of crystallizedi
silica, such as sand and quartz, for it still possesses the power o*
dissolving in alkalies and alkaline carbonates at the ordinary
temperature of the air, and this power it retains even when i*
has been heated to redness.

There is scarcely any other mineral substance which can b*
compared to silica for the possession of such remarkable proper
ties as those now described.

DECOMPOSITION OF FELSPAR. 85

Most of the insoluble silicates containing alkaline bases are
decomposed by the action of hot water, particularly when that
water contains an acid. In the middle of the last century, the
ignorance of this fact led chemists to believe that \Vater might
be converted into an earth.

When water is distilled in glass vessels, it is found to contain
always a certain quantity of earthy substances, which may be
detected by evaporation, even if the water has been subjected to
many repeated distillations. Lavoisier proved that part of the
glass was dissolved in this operation by the boiling water ; and
further, that the diminution in the weight of the glass vessel cor-
responded exactly to the quantity of earthy residue left by the
evaporation of the water. When the distillation of water is
effected in metallic vessels no such residue can be obtained.

The action of water upon the silicates contained in glass may
be observed in the opacity which gradually comes over the win-
dows of hot-beds, these being exposed in a great degree to the
influence of the air. This action is more marked in the win
dows of stables, where the carbonic acid formed by the processes
of respiration of the animals, and by the decay of animal matter,
accelerates the decomposition.

Silica being an acid of a very feeble character, the decompo-
sition of the soluble silicates is effected even by carbonic acid.

A solution of soluble glass may be converted into a gelatinous
mass by saturating it with carbonic acid gas. The same decom-
position must take place in very dilute sotutions, although we
cannot detect in them any separation of silica, which remains
dissolved in the water.

The decomposition of silicates by the combined action of water
and of acids proceeds with a rapidity proportional to the quantity
of alkalies contained in them.

We find numerous examples in the inorganic kingdom of a con-
tinued and progressing process of decomposition of the silicates
contained in the various kinds of rocks ; this decomposition is ef-
fected by the action of carbonic acid, and of water.

A consideration of the preceding observations shows clearly
that porcelain clay or kaolin has been formed by the decompos-
ing action of water on the silicates of potash and soda contained

FORMATION OF SOILS.

in felspar or felspathic rocks. Felspar* may be viewed as m
combination of silicate of alumina with silicate of potash ; the
last of which being gradually removed by water, leaves behind
the porcelain clay.

It has been shown by Forchammer, that felspar may be de-
composed by water of 150° C. (302° F.), and at a pressure cor-
responding to this temperature. The water becomes strongly
alkaline, and is found to contain silica in solution. The hot
springs in Iceland possess a high temperature, and come from a
great depth, where they must have been subjected to high pres-
sure. Forchammer has shown by analysis that the water of
these springs contains the constituents of soda felspars, and of
magnesian silicates, minerals of very frequent occurrence in
trap districts. There cannot be a doubt that a conversion of
crystalline felspar into clay must be proceeding to a great extent
at the bottom of these springs. f

Ordinary water containing carbonic acid acts in precisely
the same manner as water at a high temperature, and at a high
pressure.

Polstorf and Wiegmann boiled some white sand with a mixture
of nitric and muriatic acids, and after completely removing the

* COMPOSITION OF FELSPATHIC MINERALS.

Felspar. Albit. Labrador. A north.

Silica - - - 56-9 - - 69-8 - - 558 - - 44'5
Alumina - - - 178 - - 18-8 - - 26-5 - - 34-5
Potash - - - 16-3 - - — - _ _ . - —
Soda - - - _ . . 11-4 - - 4-0 - - —
Magnesia - - - — - - — - - — - -8'2
Lime - - - — - . _ . . iro - - 15-7
Protoxide of iron - — - - — - -1'3- -0'7

The chemical formula of felspar is AI2, O3 3 Si 0, + KO, Si 0».o
f his formula, when multiplied by three, may be divided into porcelain
clay, 3 Ala, O3, 4 Si O3, and into soluble silicate of potash, 3 Ko, 8
SiO».
t The dry residue of 28 ounces of the water consisted of—
Gypsum - - - - 0453
Sulphate of Soda > a.qo'i

Magnesia 5 " -0 827

Common Salt - - - 2 264

Soda 1-767

Silica . . - • . 0-506

ANALYSIS OF PHONOLITE. -W

acid by washing the sand with water, they exposed it thus puri-
fied to the action of water saturated with carbonic acid gas.
After the expiration of thirty days, this water was subjected to
analysis, and was found to contain in solution, silica, carbonate
of potash, and also lime and magnesia ; thus proving that the
silicates contained in the sand were unable to withstand the con-
tinued action of water containing carbonic acid, although the
same silicates had resisted the short action of the aqua regia.

Certain of the alkaline silicates found in nature contain in their
crystalline state water in chemical combination. In this class
are the zoolites, analcime, mesotypc, sodalite, apophyllite, <^g. ;
the felspars, properly so called, arc always anhydrous.

These silicates differ very much in their behavior to acid
reagents. When mesotype, or a mineral correspond in jj to it in com-
position, is kept in the state of a fine powder in contact with cold
muriatic acid, it increases in bulk to a thick jelly. The mineral
being exposed to the action of the acid at the ordinary tempera-
ture, those constituents which are soluble in the acid are taken
up by it, whilst the greatest part of the silica remains undissolv-
ed. Labrador spar (calcareous felspar) behaves similarly when
treated with acids ; but the minerals adularia and albite (potash
and soda felspars) are not attacked by acids under similar cir-
cumstances.

The difference in properties, with respect to reagents, enables
us to decompose very complex kinds of rocks into their constitu-
ent parts. C. Gmelin used a process in the analysis of phonolite,
or clinkstone rock, by which we may separate and determine
the amount of the minerals capable of disintegration contained
in different kinds of rocks or soils submitted to examination. For
example, phonolite from Abtcrode in the district of Hegau wa«
found to contain* —

2*097 of a mineral analogous to mesotype, and soluble in acid*
11 '142 of felspar, insoluble in acids

The constituents of both these are as follows : —
• Poggendorf *s Annalen, Bd. x.,p 357,

FORMATION OF SOILS.

The portion Insc'.ub'.e

soluble in acids. residue.

Silica - - . - 38 574 - - 66-291

Alumina- - - - 24-320 - - 16-510

Potash - - - - 3079 - - 9-249

Soda - - - . 12-656 - - 4-960

Lime - - - . i 802 - - A trace.

Peroxide of iron - - 11*346 - - 2-388

Peroxide of manganese - 2-194 - - 0-896
Titanic acid - - - 0620
Water ... - 4209
Organic substances - - 0 4 05
Jn a similar manner, Frick has analysed clay slate, and Lowe
the basalt and lava from Mount Etna.

C 4-615 Magnetic Iron Ore.
Basalt contains in 100 parts < 39 800 Zeolite.*
( 55-885 Augite.f

By treating clay slate from Bendorf with muriatic acid, it was
decomposed into —

26-4G parts soluble in muriatic acid.
73-54 parts insoluble in muriatic acid.

The composition of these was as follows :■ —

Soluble part Insoluble part

of clay slate. of clay slato.

Silica 22-39 - - - 7706

Alumina 19-35 - - - 1599

Peroxide of iron 27-61 - - - 1-53

Magnesia 7-00 - . . 0 57

Lime 242 - - - 3-94

Potash without soda . - - . 237 - - - 3*94

Water, carbonic acid, and loss - - 18-86 - - - 0-39
Oxide of copper ----- -_-_ 0-19

From these analyses we may deduce some highly important
reiults.

It is known that felspar is unable to resist the solvent action

* Zeolite contains —

Silica . - . - - 38-83

Alumina 28*77

Lime 1045

Soda 13-81

Potash 1-42

Water 672

t Augite is a silicate of lime and magnesia

FORMATION OF CLAYS.

89

of water, saturated with carbonic acid, although it is scarcely
affected by being left in contact with cold muriatic acid for
twenty-four hours. The analyses given above show that the
most widely diffused rocks contain a mixture of silicates, which,
being soluble in cold muriatic acid, must be much more easily
attacked than felspar by water holding in solution carbonic acid.

All minerals and rocks containing silicates of alkaline bases
are incapable of resisting the continued solvent action of carbonic
acid dissolved in water. The alkalies, with lime and magnesia,
will either dissolve alone, or the former will enter into solution
along with silica, while the alumina remains behind, mixed or
combined with silica. Disintegrated phonolite from Abterode,
formed by the action of air and moisture on the solid mineral
(the analysis of which is given above), behaves to acids in a
manner quite different from the latter.

The mineral clinkstone contains more than 20 per cent, of
ingredients soluble in muriatic acid, whilst the same mineral,
when disintegrated, does not contain more than 5 per cent, of
soluble constituents.*

The insoluble portion of disintegrated phonolite is scarcely
altered. in composition: in the soluble portion, iron and mangan-
ese form the principal constituents : these two oxides exist in the
soluble portions of the undisintegrated mineral in the proportion
of 11-346 : 2-194 ; and in the disintegrated mineral, 100 parts
contain 63-39 of peroxide of iron to 11-3 of peroxide of man-
ganese, or nearly the same proportion as the former.

In the process of disintegration, therefore, the alkalies, lime,
and magnesia, have been dissolved and carried away by water
along with silica and alumina ; and the residue contains only -^
the amount of the alkalies originally present. But as long as
the mineral contains a trace of an alkali, or of any base soluble

• The soluble part of disintegrated

The insoluble portion of disinte-

clinkstone contains —

grated clinkstone contains—

Silica - - - -

13-396

Silica -

- - -

66-462

Alumina - - _

5-660

Alumina

- - -

16810

Potash (Soda)

1-07.1

Potash

- - -

9-569

Lime . - - .

Soda -

>

4-281

Peroxide of Iron -

63-396

Lime -

, - -

1-523

Peroxide of Manganese -

11 132

Peroxide of Iron -

2-989

Titanic Acid

3-396

Peroxide of

Manganese

0-173

FORMATION OF SOILS.

in carbonic acid, water containing that gas continues to exercise
an action upon it, and effects a progressive disintegration of its
constituents.

Forchammor considers that the yellow clay, which occurs so
frequently in Denmark, consists of granite, the felspar of which
has been altered, whilst its mica remains unchanged, and its
quartz forms the sand of the clay.

The magnetic and titanic oxides of iron existing in granite are
still found in the clay as peroxide of iron and titanic acid.

The blue clays arise from syenite and greenstone ; for in these
mica is absent (Forchammer).

The great strata of clay at Halle have had their origin in the
disintegration of porphyry.*

The white basis of the clay is easily distinguished by moisten-
ing it : while the felspar may be recognised by its yellow color
(Mitscherlich). The silica, dissolved by the potash, or soda, is
sometimes found deposited in a crystalline form on the crystals
of felspar ; this is often observed in the trachyte of the Seven
Mountains near Bonn (Mitscherlich). Most sand-stones contain,
mixed with them, silicates with alkaline bases. In the sandstone
of the Holy Mountain near Heidelberg, many unchanged frag-
ments of felspar are observed, which are partly changed into
clay and form white points in the sandstone.

The analysis of the porcelain clays proves that the felspars
from which they were formed have not reached their utmost
limit of disintegration, for they still contain potash. The porce-
lain clays are those which are refractory in the fire, and do not
melt when exposed to the strongest heat of our furnaces. The
difficult fusibility of the porcelain clays depends upon their
small proportion of the alkaline bases, potash, soda, lime, mag-

*The

decomposed felspar,

porcelain clay

of

Mori, 1

near

Halle,

iists of—

Silica -

-

.

71-42

Alumina

.

-

26-07

Peroxide of

iron -

-

1-93

Lime

-

-

013

Potash 0-45

FORMATION OF CLAYS. 61

nesia, and protoxide of iron.* When we compare the other
kinds of clay with the porcelain clays, we find that the infusible
clays, or clays poor in potash, are of rare occurrence. The
clays diffused through the most kinds of rocks, those occurring
in arable land, and those in the beds of clay interspersed with
the layers of brown and mineral coal, contract when exposed to
heat, and become vitrified in a strong fire. Loam also melts in
a similar manner. When the oxides of iron are not present in the
clays, their fusibility is in direct proportion to the amount of their
alkaline ingredients. Clays arising from the disintegration of the
potash felspars, are free from lime ; those formed from Labrador
spar (the principal component of basalt and lava), contain lime
and soda.

The limestones containing much clay are proportionally the
richest in alkaline ingredients. The marls and stones used for
cement belong to this class of minerals. They differ from other
limestones by possessing the property, after moderate burning,
of hardening when in contact with water. During the burning
of marl and of many other natural cements, the constituents of
the clay and lime act chemically upon each other, giving rise to
an anhydrous apophyllite, or an analogous compound of silicate
of potash and silicate of lime, which, being brought in contact
with water, forces the latter into chemical combination in a man-
ner similar to burnt gypsum, and crystallizes along with it.f
When a fragment of chalk is moistened with a solution of silicate
of potash, the latter forms a new compound on the surface, and
this becomes hard and stony. The lime of the chalk takes the
place of potash in the silicate of potash, and a certain quan-

* COMPOSITIOX OF PORCELAIN CI.AYS.

St. Yvreux. Meissen.

Silica - - - 46S - - - 52-8
Alumina - - 37-3 - - - 31-2

Potash - - - 2-5 - - - 2-2

Schneeberg.
Silica - - - - 43-6
Alumina - - - - 37"7
Peroxide of iron - - I'D

Potash and water - - 12*5
t Formula of Apophyllite— Ko, 2 Si O3 + 8 Ca 0, Si O 3 + 16 aq

FORMATION OF SOILS.

tity of potash is set at liberty in the form of a carbonate
(Kuhlmann),

The preceding considerations prove very clearly that arable
land has had its origin in the chemical and mechanical actions
exerted upon rocks and minerals rich in alkalies and alkaline
earths, by which means their coherence has been gradually
destroyed. It is scarcely necessary to furnish any further proofs
that all clays, whether they be pure or mixed with other minerals,
so as to form soils, suffer progressive and continued changes.
These changes consist in the giving of a soluble form to the
alkalies and alkaline bases, by the combined action of water and
of carbonic acid. This gives rise to the formation of soluble
silicates, or if these are decomposed by- the carbonic acid, to the
hydrate of silica, which, being in its peculiar soluble condition,
may be taken up by the roots of plants.

The influence of air, carbonic acid, and moisture, upon the
constituents of rocks, is best observed in certain uninhabited dis-
tricts of South America, where huntsmen and herds are the dis-
coverers of rich mines of silver. By the action of the weather
the constituents of the ores of silver are gradually dissolved and
carried away by winds and by rains ; the nobler metals resist the
destruction and remain on the surface. It is well known that
metallic silver veins are found in sharp angular projections from
the surface of the rock.*

* Darwin states that the mine at Chanuncillo, from which silver to the
value of many hundred thousand pounds sterling has been obtained in a
few years, was discovered by a man who. in throwing a stone after a mule,
found it heavier than an ordinary stone ; it was a piece of solid silv< r, and
was a fragment of a projecting vein of tlat metal.

INSOLUBILITY OF HUMUS.

CHAPTER IX.

The Art of Culture.

The conditions necessary for the life of all vegetables have been
considered in the preceding part of the work. Carbonic acid,
ammonia, and water, yield elements for all the organs of plants.
Certain inorganic substances — salts and metallic oxides — serve
peculiar functions in their organism, and many of them must be
viewed as essential constituents of particular parts.

The atmosphere and the soil offer the same kind of nourish-
ment to the leaves and roots. The former contains a compara-
tively 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 consideration 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 would remove a great part of it from the ground,
and a heavy and continued rain would impoverish a soil. But
humus is soluble only when combined with oxygen ; it can be
taken up by water, therefore, only as carbonic acid.

When moisture is absent, humus may be preserved for cen-
turies : but when moistened with water, it converts the surround-
ing 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
•uffers no further change. Its decay proceeds only when plants
grow in a soil containing it ; for they absorb by their roots the

THE ART OF CULTURE.

carbonic acid as it is formed. But the soil receives again from
living plants the carbonaceous matter it thus loses, so that the
proportion of humus in it does not decrease.

The stalactitic caverns in Franconia, and those in the vicinity
of Baireuth and Streitberg, lie beneath a fertile arable soil ; the
abundant decaying vegetables or humus in this soil, being acted
on by moisture and air, constantly evolve carbonic acid, which
is dissolved by the rain. The rain-water thus impregnated per-
meates the porous limestone, which forms the walls and roofs of
the caverns, and dissolves in its passage as much carbonate of
lime as corresponds to the quantity of carbonic acid contained
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 wh^re
so many circumstances favorable to the production of humate of
lime are combined, if the humus actually existed in the soil in
the form of humic acid. Decaying vegetable matter, water, and
lime in solution, are brought together, but the stalactites formed
contain no humic acid ; they are of a glistening white or yellow-
ish color, in part transparent, like calcareous spar, and may be
heated to redness without becoming black.

The subterranean vaults in the old castles near the Rhine, in
the " Bergstrass," and in the Wetterau, are constructed of sand-
stone, 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 the result of experiments which have been
continued for hundreds or thousands of years. Now, if water
possessed the power of dissolving a hundred-thousandth part of
its own weight of humic acid or humate of lime, and if humio

INSOLUBILITY OF HUMUS.

acid were present, we should find the inner surface of the roofs
of these vaults and caverns covered with these substances ; bu/
we cannot detect the smallest trace of them. We must feel con-
vinced that humic acid is absent both from the soils of fields and
of gardens, when we consider that humic acid gives to water a
dark brown color, whereas well and spring water is quite clear
and colorless, and leaves after evaporation only a residue of salts
formed by mineral acids, without humic acid. The water of
wells and of springs is actually rain-water which, in passing
through the soil, must exert all its solvent action on the humates.
If humate of potash existed in soils, all the spring and river water
collected at a certain depth ought to contain traces of it. But
even the mineral waters from the springs of Seller and Fachin-
ger, containing alkaline carbonates, are destitute of a trace of
humic acid ; although these waters arise in a marshy soil abound-
ing in vegetable matter. There could scarcely be found more
clear and convincing proofs of the absence of the humic acid of
chemists from common vegetable mould.

The common view adopted respecting the modus operandi of
humic acid does not afford any explanation of the following phe-
nomenon : — A very small quantity of humic acid dissolved in
water gives to it a yellow or brown color. Hence it would be
supposed that a soil would be more fruitful in proportion as it
was capable of giving this color to water, that is, of yielding it
humic acid. But it is very remarkable that cultivated 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 cultivated plants is that which has
completely lost the property of giving a color to water.

The soluble substance, which gives to water a brown color, is
a product of the putrefaction of all animal and vegetable mat-
ters ; its formation is an evidence that there is not oxygen sufli
cient 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 sub*

96 THE ART OF CULTURE.

stance named " coal of humus." Now if a soil were impreg-
nated with this matter, the effect on the roots of plants would be
the same as that of entirely depriving the soil of oxygen ; plants
would be as little able to grow in such ground as they would if
hyd rated protoxide of iron were mixed with the soil. All plants
die in soils and water destitute of 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. When the water is withdrawn from a
marsh, free access is given to the air, and the marsh is changed
into a fruitful meadow.

In a soil to which air has no access, or at most but very little,
the remains of animals and vegetables do not decay, for they can
only do so when freely supplied with oxygen ; but they undergo
putrefaction, for the commencement of which air is present in
sufficient quantity. Now putrefixction 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 oxygen can be extracted yield it to
putrefying bodies ; yellow oxide of iron passes into the state of
black oxide, sulphate of iron into sulphuret of iron, &c.

The frequent renewal of air by ploughing, and the prepara-
tion of the soil, especially its contact with alkaline metallic ox-
ides, the ashes of brown coal, burnt lime, or limestone, change
the putrefaction of its organic constituents into a pure process of
oxidation ; and from the moment at which all the organic matter
existing in a soil enters into a state of oxidation or decay, its fer-
tility is increased. The oxygen is no longer employed for the
conversion of the brown soluble matter into the insoluble coal of
humus, but serves for the formation of carbonic acid. This
change takes place very slowly, and in some instances the oxygen
is completely excluded by it ; and whenever this happens, the
soil loses its fertility. Thus, in the vicinity of Salzhausen (a
village in Hesse Darmstadt, famed for its mineral springs), upon
the meadows of Griinschwalheim, 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

IMSOLUBILITY OF HUMUS.

acid is emitted from it with such violence that the noise made by
the escape of the gas may be distinctly heard, at the distance of
several feet. Here the carbonic acid rising to the surface dis-
places completely all the air, and consequently all the oxygen,
from the soil ; and without oxygen neither seeds nor roots can be
developed ; a plant will not vegetate in pure nitrogen or carbonic
acid gas.

Humus supplies young plants with nourishment in the form
of carbonic acid by the roots, until their leaves are matured
sufficiently to act as exterior organs of nutrition ; its quantity
heightens the fertility of a soil by yielding more nourishment in
this first period of growth, and consequently by increasing the
number of organs of atmospheric nutrition. Humus acts in
this respect as a source of carbon to plants ; but vegetable mould
contains other substances which are equally necessary to plants.
Vegetable mould contains invariably carbonate of ammonia,
besides the salts and alkalies left behind by the putrefaction of
former plants.* Those plants which obtain their first food from
the substance of their seeds, such as bulbous plants, could com-
pletely 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 measure injurious.

The amount of food capable of being extracted by young

* Some vegetable mould taken from the interior of a hollow oak, yielded
To'a'o' of residue after incineration ; of this residue 100 parts contained 24
parts of soluble salts with alkaline bases, 10*5 parts of earthy phosphates,
10 parts of earthy carbonates, and 32 parts of silica. The aqueous extract
gave 66 per cent, of soluble salts. (Saussure.) One thousand parts of
the extract obtained by hot water from vegetable mould formed by the de-
cay of the Rhododendron Fcrrugineum gave 140 parts of ashes, which
contained, according to Saussure :

Carbonate of potash - - - 14
Chloride of potassium - - 23
Siilphate of potash - - - 16
Earthy phosphates - - - 17*25
Earthy carbonates - - - 21 "50
Silica - - - - - 3-25 t

Metallic oxides and loss - - 5"00
fi

THE ART OF CULTURE.

plants from the atmosphere, in the form of carbonic acid and
ammonia, is limited ; they cannot assimilate more than the aif
contains. Now, if the quantity of their stems, leaves, and
branches, has been increased by the excess of food yielded by the
soil at the commencement of their development, they will require
in a given time for the completion of their growth, and for the
formation of their blossoms and fruits, more nourishment from
the air than it can afford, and consequently they will not reach
maturity. In many cases, the nourishiT>snt afforded by the air
under these circumstances suffices only to complete the forma-
tion of the leaves, stems, and branches. The same result then
ensues as when ornamental plants are transplanted from the pots
in which they have grown to larger ones, in which their roots
are permitted to increase and multiply. All their nourishment is
employed for the increase of their roots and leaves; they grow
luxuriantly, but do not blossom. When, on the contrary, w^
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 pur-
pose that vines are pruned.

A new and peculiar process of vegetation ensues in all peren-
nial plants, such as shrubs, fruit and forest trees, after the com-
plete maturity of their fruit. The leaves of annual plants at
this period of their growth change in color ; while 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
afler August no more new wood is formed ; 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'AoAt).* According to the observa-
tions of M. Heyer, the starch thus deposited in the body of the
tree can be recognised in its known form by the aid of a good

• Hartlg, in Erdmann und Schweigger-Seidels Jourtal, V 217. 1836.

EXCESS OF NUTRIMENT.

microscope. The barks of several aspens and pine-trees* con-
tain so much 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 formation 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 pro-
duced in the succeeding spring, while from these the unnitrogen-
ized constituents of the leaves and young sprouts are in their turn
formed. After potatoes have germinated, the quantity of starch
in them is found to be diminished. The juice of the maple-tree
loses sugar and ceases to be sweet, 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 or rain-water ; but in
proportion as it grows, the starch disappears, it being evidently
exhausted for the formation of the roots and leaves.

Upon the blossoming of the sugar-cane, likewise, part of the
sugar disappears ; and it has been ascertained, that the sugar
does not accumulate in the beet-root until after the leaves are
completely formed.

These well-authenticated observations remove every doubt as
to the functions performed by sugar, starch, and gum, in the de-
velopment of plants ; and it ceases to be enigmatical, why these
three substances exercise no influence on the growth or process
of nutrition of a matured plant, when applied to it as food.

The accumulation of starch in plants during the autumn has
been compared, although certainly erroneously, to the fattening
of hibernating animals before their winter sleep ; but in these
animals every vital function, except the process of respiration, is
suspended, and they only require, like a lamp slowly burning, a
substance rich in carbon and hydrogen to support the process ot
combustion in the lungs. On their awaking from their torpor in

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

100 THE ART OF CULTURE.

the spring, the fat has disappeared, but has not served as nourish-
ment. 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 albumen, starch and gum, which are used
by the germs for the formation of their leaves and first fibres of
the radicle. The proper nutrition of the plants, their increase
in size, begins after these organs are formed.

Every germ and every bud of a perennial plant is the en-
grafted embryo of a new individual, while the nutriment accu-
mulated in the stem and roots corresponds 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 the materials for the production of their peculiar
constituents.

In animals, the blood is the source of the material of the mus-
cles 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 the blood, but its own production is a special function, without
which we 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 another, at all events, if we carry
this beyond certain limits, death is the consequence.

The smallest particles of sugar, when left to themselves,
crystallize, that is, they obey a power strictly chemical. It is
evident that starch and woody fibre are more highly organized
compounds than sugar, for they possess a form which they could
not have obtained by the mere power of cohesion. We may
suppose that starch and woody fibre were originally gum and
sugar, or that both have been formed from sugar ; but certain
conditions must be necessary for the conversion of sugar into
•tarch, so that it will not be afliected when these conditions fail.

CONDITIONS ESSENTIAL TO NUTRITION 101

Other substances must be present in a plant, bevs-ictes the ^stai'oh;
sugar, and gum, if these are to take part in the development of
the germ, leaves, and first fibres of the radicle. There is no
doubt that a grain of wheat contains within itself the component
parts of the germ and of the fibres of the radicle. These compo-
nent parts are starch and gluten ; and it is evident that neither
of them alone, but that both simultaneously assist in the formation
of the root, for they both suffer changes under the action of air,
moisture, and a suitable temperature. The starch is converted
into sugar, and the gluten also assumes a new form, and both
acquire the capability of being dissolved in water, and of thus
being conveyed to every part of the plant. Both the starch and
the gluten are completely consumed in the formation of the first
part of the roots and leaves ; an excess of either could not be
used in the formation of leaves, or in any other way.

The conversion of starch into sugar during the germination of
grain is ascribed to a vegetable principle called diastase, which
is generated during the act of commencing germination. But
this mode of transformation can also be etfected by gluten, al-
though it requires a longer time. Seeds, which have germinated,
always contain much more diastase thanisnecessary for the conver-
sion of their starch into sugar, for five parts by weight of starch crxu
be converted into sugar by one weight of malted barley. This
excess of diastase can by no means be regarded as accidental,
for, like the starch, it aids in the formation of the first organs of
the young plant, and disappears with the sugar.

Carbonic acid, water, and ammonia, are the food of fully-d;^-
veloped plants ; starch, sugar, and gum, serve, when accompanied
by an azotized substance, to sustain the embryo, until its first
organs of nutrition are unfolded. The nutrition of a fcetus and
development of an egg proceed in a totally different manner from
that of an animal which is separated from its parent; the exclu-
sion of air does not endanger the life of the foetus, but would
certainly cause the death of the independent animal. In the
same manner, pure water is more advantageous to the growth of
a young plant than that containing carbonic acid, but afler a
month the reverse is the case. (Saussure.)

The formation of sugar in the maple-trees does not take place

!02 THE ART OF CULTURE.

iki the -roots, but in the woody substance of the stem. The
quantity of sugar in the sap augments until it reaches a certain
height in the stem of the plant, above which point it remains
stationary.

Just as germinating barley produces a substance which, in
contact with starch, causes it to lose its insolubility and to become
sugar, so in the roots of the maple, at the commencement of vege-
tation, a substance must be formed, which, being dissolved in
water, permeates the wood of the trunk, and converts 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 possi-
ble that this sugar may be disposed of in the same manner as
that formed in the trunk; 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 ex-
creted from the surface of the leaves or bark. Certain diseases
of trees, for example that called honey-dew, evidently depend on
the want of the due proportion between the quantity of the azo-
tized and that of the unazotized substances which are applied to
them as nutriment.

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 containing that element.

The wood of the stem cannot be formed, qua 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
nitrogen ; it is very probable that the wood and the vegetable
gluten, the starch granules and the cells containing them, are
formed simultaneously, and in this case a certain fixed proper.

CONDITIONS ESSENTIAL TO NUTRITION. 103

tion between them would be a condition necessary for their
production.

In the buds and young leaves, we find salts with alkaline bases ;
we find also the azotized constituents invariably accompanied by
salts of phosphoric acid : we must, therefore, suppose that these
substances execute some functions necessary to the support of
the vital processes of plants. We may suppose that, in the ab-
sence of certain constituents of the soil, the compounds of plants
containing nitrogen and sulphur could not be formed, and that
without the presence of such compounds and of alkaline bases,
carbonic acid could not be taken up and decomposed.

According to this view, the assimilation of the substances
generate' in the leaves will (cceteris paribus) depend on the
quantity f nitrogen contained in the food. When a sufficient
quantity if nitrogen is not present to aid in the assimilation of
the substances destitute of it, these substances will be separated
as excrements from the bark, roots, leaves, and branches. The
exudations of mannite, gum, and sugar, in strong and healthy
plants, cannot be ascribed to any other cause.*

Analogous phenomena are presented by the process of diges-
tion in the human organism. In order to restore the loss sus-
tained by every part of the body in the processes of respiration
and perspiration, the organs of digestion require to be supplied
with food, consisting of substances containing nitrogen and of
others destitute of it, in definite proportion, and also with certain
mineral substances to effect their transformation into blood. If
tlie substances d< ?titute of nitrogen preponderate, either they
n^ill be expended in the formation of fat, or they will pass un-
jhanged through the organism. This is particularly observed

* M. Trapp, in Giessen, possesses a Clerodendron fragrans growing in
the house ; it exudes on the surface of its leaves, in September, large
colorless drops, which form regular crystals of sugar-candy upon drying ; —
I am not aware whether the juice of this plant contains sugar. Langlois
has lately observed, during the dry summer in 1842, that the leaves of the
linden-tree became covered with a thick and sweet liquid, in such quan-
tity, that for several hours of the day it ran off the leaves like drops of
rain. Many kilogrammes might have been collected from a moderately-
sized linden-tree. This sweet juice contained principally grape sugar and
mannite. (^Annales de Chimie et Phytique, iii. Serie, tom. vii., p. 34&^

104 THE ART OF CULTURE.

in those people who live almost exclusively upon potatoes; tbeii
excrements contain a large quantity of unchanged granules of
starch. 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 wholesome fodder.

It will be evident from the preceding considerations, 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, cannot be converted
either into gluten, albumen, or wood ; but either it will be sepa-
rated 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.

The quantity of gluten, and of vegetable albumen, will
augment when plants are supplied with an excess of food con-
taining nitrogen, if certain otiier conditions be fulfilled ; and
ammoniacal salts will remain in the sap, when, for example, as
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 quantity of leaves when treated
with rich animal manure, without the fruit on that account ac-
quiring a larger amount of sugar ; that the quantity of starch in
potatoes increases when the soil contains much humus, but de-
creases when the soil is manured with strong animal manure,
although then the number of cells increases, the potatoes acquir-
ing in the first case a mealy, in the second a soapy, consistence.
Beet-roots taken from a barren sandy soil, contain a maximum
of sugar, and no ammoniacal salts; and the Teltowa parsnip
loses its mealy state in a highly manured land, because there
all the circumstances necessary for the formation of cells are
united.

An abnormal production of certain component parts of plants
presupposes a power and capability of 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

EFFECT OF LIGHT ON CHEMICAL COMBINATION. lOJ

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 of decomposing water under
the influence of light, and of setting 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 carbonic
acid absorbed by it.

In living plants and in their seeds, there exists a peculiar
power different from all other causes of increase of mass. This
power, however, only shows itself in action when aided by the
influence of heat or of light. In spring, when the heat of the sun
penetrates the earth, the asparagus may put forth shoots of
many feet in length quite independently of the action of light.
But the constituents of these shoots were formerly constituents
of the roots. A conversion of pre-existing compounds into new
products, and their assumption of new forms, can proceed with-
out light, although not without heat. But this is not a true in-
crease of mass, or an increase in the quantity of carbon. The
latter process only takes place under the influence of light.

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 sun-light, but it is not necessary that the direct
rays of the sun should 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 muriatic acid.
This combination is effected in a few hours in common daylight,
but it ensues instantly, with a violent explosion, under exposure
to the direct solar rays, whilst not the slightest change in the
two gases takes place in perfect darkness. When the oil formed
from defiant gas is exposed in a vessel with chlorine gas to the

106 THE ART OF CULTURE.

direct solar rays, chloride of carbon is immediately produced ;
but the same compound can be obtained with equal facility in
the diffused ligh of day, a longer time only being required.
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 constantly
augments, until at last the whole oil 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,
with the exception of certain parasites which obtained their car-
bon, either not at all, or only partially, from the original source ;
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 decomposition
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

* The impossibility of bringing to blossom and seed mosses and other
cryptogamous plants, in ordinary daylight, induced Mr. Noller, an excel-
lent botanist and chemist in Darmstadt, to form the opinion that the green
light from the leaves formed a necessary condition of their life. He
planted numerous kinds of these plants in mouldered wood placed in little
glass tubes, and covered the whole with a green glass globe. The experi-
ment established his view in a beautiful manner. All these elegant plants
developed under these conditions with the greatest luxuriance, and put
forth both blossoms and seeds

IMPORTANCE OF AGRICULTURE. lOT

gas, whilst the carbonic acid disappears. Now in these experi-
ments no nitrogen :^ supplied at the same time with the carbonic
acid ; hence no other conclusion can be drawn from them than
that a simultaneous introduction of nitrogen is not necessary for
the decomposition of carbonic acid, — for the exercise, therefore,
of one of the functions of plants. And yet the presence of a
substance containing this element appears to be indispensable for
the assimilation of the products newly formed by the decomposi-
tion of the carbonic acid, and their consequent adaptation for en-
tering 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 carhop aids in consti-
tuting several new products ; these are named sugar when they
possess a sweet taste, gum or mucilage when tasteless, and ex-
cremcntitious matters when expelled by the roots or other parts.

Hence it is evident that the quantity and quality of the sub-
stances 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 na-
ture 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 J.'cight and size, in the number of
its twigs, branches, leaves, blossoms, and fruit. Whilst the indi-
vidual organs of a plant increase 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 containing nitrogen, and those destitute of it,
varies with the amount of nitrogenous matter in the food of plants.

The development of the stem, leaves, blossoms, and fruit of
plants, is dependent on certain conditions, the knowledge of which
enables us to exercise some influence on certain of their internal
constituents as well as on their size. It is the duty of the natural
philosopher to discover what these conditions are ; for the funda-
mental principles of agriculture must be based on a knowledge
of them. There is no profession which can be compared in

108 THE ART OF CULTURE.

importance with that of agriculture, for to it bebngs the produc-
tion of food for man and for animals ; on it depends the welfare
and development of the whole human species, the riches of states,
and all industry, manufacturing and commercial. There is hO
profession in which the apptication of correct principles is pro-
ductive of more beneficial eifects, or is of greater and more
decided influence. 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 circumstances. (Les circonstances font les assole-
ments.) No ansvter could show ignorance more plainly.

In addition to the general conditions, such as heat, light, mois-
ture, and the component parts of the atmosphere, all of which
are necessary lor the growth of all plants, certain substances
are found to exercise a peculiar influence on their development.
These substances either are already contained in the soil, or are
supplied to it in the form of the matters known under the general
name of manure. But what does the soil contain, and what are
the components of the substances" used as a manure? Until
these points are satisfactorily determined, a rational system of
agriculture cannot exist. The power and knowledge of the
physiologistj 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 particular plants. Now, " this object
can be attained only by the application of our knowledge of such
substances as 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 specially requires
for the attainment of the object in view.

The SPECIAL object of agriculture is to obtain an abnormal

OBJECTS OF AGRICaLTURE. lOd

development and production of certain parts of plants, or of
certain vegetable matters, employed as food for man and animals^
or for the purposes of industry.

i'iie means employed vary according to the objects which it
is desired to attain. Thus, the mode of culture employed for
the purpose of procuring fine pliable straw for Tuscan hats, is
the very opposite to that which must be adopted in order to pro-
duce a maximum of corn from the same plant. Peculiar
methods must be used for the production of nitrogen in the
seeds, others for giving strength and solidity to the straw, and
others again must be followed when we wish to give such
strength and solidity to the straw as will enable it to bear the
weight of the ears.

We must proceed in the culture of plants in precisely the
same manner as we do in the fattening of animals. The flesh
of the 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. Tiie production of flesh and fat may be
artificially increased ; for all domestic animals become fat. We
give to animals food 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 increase or diminution of the vital activity of vegetables
depends only on heat and solar light, wiiich we have not arbitra-
rily at our disposal : all that we can do is to supply substances
adapted for assimilation by the power already present in the or-
gans of the plant. But what then are these substances ? They
may easily be detected by the examination of a soil always fer-
tile in the existing cosmical and atmospheric conditions ; for it
is evident that the knowledge of its state and composition must
enable us to discover the conditions under which such a soil is
rendered fertile. It is the duty of the chemist to explain the
composition of a fertile soil, but the discovery of its proper phy-
sical state or condition belongs to the agriculturist ; our present
business lies only with the former.

Arable land is originally formed by the crumbling of rocks,
and its properties depend on the nature of their principal compo«

no THE ART OF CULTURE.

nent parts. Sand, clay, and lime, are the names given to the
principal constituents 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 argillaceous earths in arable land, what are their constituents,
and what part do they play in favoring vegetation ? They are
produced by the disintegration of aluminous minerals, among
which the common potash and soda felspars, Labrador spar, mica,
and the zeolites, are those which most commonly undergo this
change. These minerals are found mixed with other substances
in granite, gneiss, mica-slate, porphyry, clay-slate, grauwacke
and the volcanic rocks, basalt, clinkstone, and lava. As mem-
bers of the grauwacke series we have pure quartz, clay-slate,
and lime ; in the sand-stones, quartz and loam. The transition
limestone and the dolomites contain an intermixture of clay,
felspar, porphyry, and clay-slate ; and the mountain limestone is
remarkable for its quantity of argillaceous earths. Jura lime-
stone contains 3 — 20, that of the Wurtemburg Alps 45 — 50 per
cent, of these earths. And in the muschelkalk and in the cal-
caire grassier they exist in greater or less quantity.

It is thus obvious that the aluminous minerals are the most
widely diffused on the surface of the earth, and, as we have
already mentioned, they are never absent from fertile soils ;
and, if they should happen to be absent in soils capable of culti-
vation, this only happens when certain of their constituents are
supplied by other sources. Argillaceous earth must, therefore,
contain something which enables it to exercise an influence on
the life of plants, and to assist in their development. The pro-
perty on which this depends is that of its invariably containing
alkalies and alkaline earths, with sulphates and phosphates.

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

* Hydrate of alumina, when mixed with extract of humus, decolorizes
this substance and renders insoluble the coloring matter. ( Wiegmann
und Polatorf \

FERTILITY OF DIFFERENT SOILS. Ill

often present, having in most cases entered the plants by means
of alkalies. In order to form a distinct conception of the quan-
tities of alkalies in aluminous minerals, it must be remembered
that felspar contains 17J per cent, of potash, albite 11*43 per
cent, of soda, and mica 3 — 5 per cent. : — and that zeolites con-
tain, on an average, 13 — 16 per cent, of alkalies.* The late
analyses of Ch. Gmelin, Lowe, Fricke, Meyer, and Redten-
bacher, have also shown, that basalt and clinkstone contain from
3 to 3 per cent, of potash, and from 5 — 7 per cent, of soda ; that
clay-slate contains from 2-75 — 3-31 per cent, of potash, and
loam from 1^ — 4 per cent, of potash.

If, now, we calculate from these data, and from the specific
weights of the different substances, how much potash must be
contained in a layer of soil, formed by the disintegration of 26,-
910 square feet (1 Hessian acre) of one of these rocks to the
depth of 20 inches, we find that a soil derived from

Felspar contains - - 1,152,000 lbs.

Clinkstone ** from 200,000 to 400,000 "

Basalt " " 47,500 " 75,000 "

Clay-slate " " 100,000 " 200,000 "

Loam " " 87,000 " 300,000 "

The alkalies, potash, and soda, are present in all clays ; at
least, they have been found in all the argillaceous earths in
which they have been sought. The fact that they contain potash
may be proved in the clays of the transition and stratified moun-
tains, as well as in the recent formations surrounding Berlin, by
simply digesting them with sulphuric acid, by which process
alum is formed. (Mitscherlich.) It is well known also to all
manufacturers of alum, that the leys contain a certain quantity
of this salt ready formed, the potash of which has its origin from
the ashes of the stone and brown coal, which .'ontains much
argillaceous earth.

A thousandth part of loam mixed with the quartz in new red
sandstone, or with the lime in the different limestone formations,
af!brds as much potash to a soil only twenty inches in depth as
is sufficient to supply a forest of pines growing upon it for a

• Recent investigations have shown that potash felspars always contain
a certain quantity of soda, and that scida felspars always contain potash.

il2 THE ART OF Ct3LTURE.

century. A single cubic foot of felspar is sufficient to supply an
oak copse, covering a surface of 26,910 square feet, with the
potash required for five years.

Land of the greatest fertility contains argillaceous earths and
other 's'ntegrated minerals, with chalk and sand in such a pro-
portion .s to give free access to air and moisture. The land in
the \ichi'. V of Vesuvius may be considered as the type of a fer-
tile soil, aik. its fertility is greater or less in different parts, ac-
cording to iis proportion of clay or sand.

This soil being derived from the disintegration of lava, cannot
possibly, owing to its origin, contain the smallest trace of vege-
table matter ; yet every one knows that when lava or volcanic
ashes have been exposed for a time to the influence of air and
moisture, all kinds of plants grow in them with the utmost luxu-
riance.

This fertility of lava is owing to the alkalies, alkaline earths,
and silica, contained in it, 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 exhaustion of
their alkalies.

We see from the composition of the water in rivers, streamlets,
and springs, how little alkali the rain-water is able to extract
from a soil, even after a term of years ; this water is generally
soft, and the common salt, which even the softest invariably con-
tains, proves that the alkaline salts, which are carried to the sea
by rivers and streams, are returned again to the land by wind
and by rain.

Let us suppose that a soil has been formed by the action of
the weather on the component parts of granite, grauwacke, moun-
tain limestone, or porphyry, and that the vegetation upon it has
remained the same for thousands of years. Now this soil would
become a magazine of alkalies in a condition favorable for their
assimilation by the roots of plants.

The interesting experiments of Struve have proved that wate?
impregnated with carbonic acid decomposes rocks containing
alkalies, and then dissolves a part of the alkaline carbonates.

DISINTEGRATION OF SOILS. 1J3

It is evident that plants also, by producing carbonic acid during
their decay, and by means of the acids which exude from their
roots in the living state, contribute no less powerfully to destroy
the coherence of rocks. Next to the action of air, water, and
change of temperature, plants themselves are the most powerful
agents in effecting the disintegration of rocks.

Air, water, and ohange of temperature prepare the different
species of rocks for yielding to plants their alkalies. A soil ex-
posed for centuries to all the influences which effect the disinte-
gration of rocks, but from which the alkalies, thus rendered
soluble, have not been removed, will be able to afford, during
many years, the means of nourishment to vegetables requiring a
considerable amount of alkalies for their growth ; 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 necessary to expose it from time to time to a
further disintegration, in order to obtain a new supply of soluble
alkalies. For, small as is the quantity of alkali essential to
plants, it is nevertheless quite indispensable for their perfect de-
velopment. But when one or more years have elapsed without
the removal of any alkalies from the soil, a new harvest may be
expected.

The first colonists of Virginia found a soil 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 abandoned and converted
into unfruitful pasture-land, which without manure produces
neither wheat nor tobacco. From every acre of this land there
were removed in the space of one hundred years 12,000 lbs. of
alkalies in leaves, grain, and straw ; it became unfruitful there-
fore, because it was deprived of every particle of alkali fit for
assimilation, and because that which wais rendered soluble again
in the space of one year was not sufiicient to satisfy the demands
of the plants. Almost all the cultivated land in Europe is in
this condition ; fallow is the term applied to land left at rest for
further disintegration. It is the greatest possible mistake to sup.
pose that the temporary diminution of fertility in a soil is owing

114 THE ART OF CULTURE.

to the loss of humus ; it is the mere consequence ot* the exhaus-
tion of alkalies, and of other essential ingredients.

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
another, and between them there are no rq^ds, 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 cir-
cumstances, when it is not even known whether 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 that could be adopt-
ed. A field is ploughed 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 lies
fallow, further than that it is exposed to the influence of the
weather, by which a fresh portion of its alkalies is again set
free or rendered soluble. The animals fed on these fields yield
nothing to them which they did not formerly possess. The weeds
upon which the cattle live spring froni the soil, and the materials
returned to it in the form of excrements must always be less in
quantity than those removed as food. 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, as well as tobacco,
is of the class of 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 com requires certain phosphates, and these
substances a soil of humus cannot afford, since it does not contain

COMPOSITION OF SOILS. us

them ; the plant may, indeed, under such circumstances, become
a 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 and certain other
ingredients in sufficient quantity, the growth of wheat being ar-
rested by this circumstance, even should all other substances be
presented in abundance.

It is not mere accident that we find on soils of gneiss, mica-
slate, and granite in Bavaria, of clinkstone on the Rhone, of
basalt in the Vogelsberg, and of clay-slate on the Rhine and in
the Eifel, the finest forests of oaks, which cannot be produced on
the sandy or calcareous soils upon which firs and pines thrive.
It is explained by the fact that trees, the leaves of which are re-
newed annually, require for their leaves six to ten times more
alkalies than the fir-tree or pine, and hence they do not attain
maturity when placed in soils containing very small quantities
of alkalies.* When we see oaks growing on a sandy or calca-
reous soil — or the red-beech, the service-tree, and the wild-cherry,
for example — thriving luxuriantly on limestone, we may be as-
sured that alkalies are j)resent in the soil, for they are necessary
to their existence. Can we, then, regard it as remarkable, that
oak copse should thrive in America, on those spots on which
forests of pines which have grown and collected alkalies for cen-
turies, have been burnt, and to which the alkalies are thus at
once restored ; or that the Spariium scoparium, Erysimum latifo-
Jium, Blitum capitatum, Senecio viscosus, plants remarkable for
the quantity of alkalies contained in their ashes, should grow
with the greatest luxuriance on the localities of conflagrations ?f

* One thf^ \sand parts of the dry leaves of oaks yielded 55 parts of ashes,
of which 9^ parts consisted of alkalies soluble in water ; the same quantity
of pine lea' es gave only 29 parts of ashes, which contain 4'G parts of solu-
ble salts. (De Saussure.)

t After the great fire in London, large quantities of the Erysimum fati-
folium, were observed growing on the spots where a fire had taken place.
On a similar occasion the Blitum capitatum was seen at Copenhagen, the
Senecio viscosus in Nassau, and the Spartiitm scoparium in Languedoc.

lt« THE ART OF CULTURE.

All plants of the grass kind require silicate of potash. Now
this is conveyed to the .soil, or rendered soluble in it by the irri-
gallon of meadows. The equisetacea, the reeds and species of
cane containing such large quantities of siliceous earth, or sili-
cate of potash, thrive luxuriantly in marshes, in argillaceous
soils rich in potash, and in ditches, streamlets, 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
Heidelberg after a thunder-storm. This mass was at first sup-
posed to be a meteor, but was found on examination (by Gmelin)
to consist of silicate of potash ; a flash of lightning had struck a
stack of hay, and nothing was founa in its place except the melted
ashes of the hay.

Alkalies and alkaline earths are not, however, the only sub-
stances necessary for the existence of most plants ; but other
substances besides alkalies are required to sustain the life of plants.

Phosphoric acid has been found in the ashes of all plants hither-
to examined, and always in combination with alkalies or alka-
line earths. By incinerating the seeds of wheat, rye, maize, peas,
beans, and lentils, ashes are obtained quite free from carbonic
acid, and consisting entirely of phosphates, with the exception of
very small quantities of sulphates and of chlorides.

Plants obtain their phosphoric acid from the soil. It is a con-
stituent of all land capable of cultivation, and even the soil of
the heath at Liineburg contains it in appreciable quantity. Phos-
phoric acid has been detected also in all mineral waters in which
its presence 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 crys-
tallized phosphate of lead (green lead ore) ; clay slate, which
forms extensive strata, is covered in many places with crystals
of phosphate of alumina (Wavellite) ; all its fractured surfaces
are overlaid with this mineral.

Apatite (phosphate of lime of similar composition to bone earth)

After the burnings of forests of pines in North America poplars grew on
the same soil

FERTILITY OF SOILS. 117

is found in every fertile soil. This mineral may be easily recog-
nised, in its crystalline form, in many varieties of rocks. It
occurs in this state in the plutonic, volcanic, and metamorphic
rocks, although it is usually found only in small quantity. In
the plutonic and volcanic rocks it is found in granite (as in the
mines of Johann Georgenstadt, Schneeberg, and in the loose
gravel near Berlin) ; in syenite it occurs in small crystals, as at
Meissen, and in larger crystals at Friedrichswern, in South Nor-
way. It exists also in hypersthene, as at Elfdalen, in Sweden,
and very often in large quantity, as at Meiches, in the Vogels-
berge (a district celebrated for its fertility in wheat), and also in
the hills of Lobau, in Saxony ; Tuhlowitz, in Bohemia, &c.
It is found in basalt and other volcanic rocks in various localities ;
for example, at Wickenstein, at Hamberg, and also at Cabo de
Gata, in Spain, and in the volcanic boulders of the Laacher See.
Apatite is found also in the metamorphic rocks, and particularly
in the talc and chloritic schists ; it occurs in large yellow crys-
tals in the micaceous schists of Snarum, in Norway ; and in the
calcareous deposits of Pargas, in Finland, and in the Lake Baikal ;
in the deposits of magnetic iron ore in Arendal, and in other
places in Sweden and in Norway. It is found also in the
oceanic rocks, particularly as round fragments and grains in the
chalk of Cape la Heve, at Havre, and of the Capes Blancnez and
Grisnez, at Calais, and in the layers of limestone at Amberg,
&c. (GusTAvus Rose.)

The water of the imperial spring at Aix la Chapelle contains,
according to Monheim, 0*142 grains of phosphate of soda in 1 lb. ;
that of the Quirinus Spring contains the same quantity, and the
water of the Rose spring contains 0*133 of the same salt. The
water of the fountain of Carlsbad contains 0*0016 grains of phos-
phate of lime. (Berzelius.) The Ferdinand's spring contains
0*010 phosphate of soda, according to Wolf. The saline springs
of Pyrmont contain 0*022 phosphate of potash, 0*075 phosphate
of lime, and 0*1249 grains phosphate of alumina. (Krueger.)
When we consider that sea-water contains phosphate of lime in
such small quantity that its amount cannot be determined in a
pound of water, and yet from this quantity all the living animah
in the sea receive the phosphates contained in their bones and fleshj

^18 THE ART OF CULTURE.

we must admit that the amount of phosphates in the above men-
tioned mineral waters is very considerable. It may be shown
by calculation that the water of the fountain at Carlsbsui
must take up many thousand pounds of phosphate of lime in its
passage through the layers of rocks.

A few very simple experiments point out the manner in which
the earthy phosphates, and particularly phosphate of lime, are
taken up by the roots of plants.

Phosphate of lime is insoluble in pure water, but it dissolves
readily in water containing common salt, or a salt of ammonia ;
and in water containing sulphate of ammonia it dissolves as
readily as gypsum. Phosphate of lime is also soluble in water
containing carbonic acid ; in this respect it is analogous to car-
bonate of lime.

The soil in which plants grow furnishes their seeds, roots, and
leaves, with phosphoric acid, and they in turn yield it 'to
animals, to be used in the formation of their bones, and of those
constituents of the brain which contain phosphorus. We may
form an idea of the quantity of phosphate of magnesia contained
in grain, when we consider that the concretions in the caecum
of horses 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 lbs. ; and Dr. F. Simon has
lately described a similar concretion found in the horse of a
carrier, which weighed 1^ lbs.

Some plants extract other matters from the soil besides
silica, the alkalies, alkaline earths, sulphuric and phosphoric
acids, which are essential constituents of the plants ordinarily
cultivated. These other matters, we must suppose, supply, in
part at least, the place, and perform the functions, of the sub-
stances just named. We may thus regard common salt, nitre,
chloride of potassium, and other matters, as necessary constitu-
ents 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

FERTILITY OF SOILS. 119

also are absorbed into plants, although we cannot affirm that they
are necessary to them.

It appears that in certain cases fluoride of calcium may take
the place of the phosphate of lime in the bones and teeth ; at
least it is impossible otherwise to explain its constant presence in
the bones of antediluvian animals, by which they are distin-
guished 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 in-
terior of the vessel will, after twenty-four hours, be found
powerfully corroded (Liebig) ; whilst the bones and teeth of
animals of the present day contain only traces of it. (Ber-

ZELIUS.)*

In spring and in the first half of the summer, when the
earth is still moist with water, it is quite certain that a greater
quantity of alkaline bases and of salts must enter the organism
of a plant, than in the height of summer, when there is a
deficiency of water, this being the means of carrying the bases
to the plant.

In many districts the crops of corn for the whole year depend
upon a single shower of rain ; for when water is deficient at a
certain period of the growth of plants, their future progress is-
retarded. The introduction of water to a soil is, properly speak-
ing, an introduction of alkalies and of certain salts, which, by
means of rain-water, become fit to be absorbed by plants. In
the middle of summer the air is much more charged with the
vapor of water than at other seasons of the year, and, therefore,

* The researches of Daubeny, however, tend to show, not only that the
amount of fluoride of calcium in bones is larger than is commonly sup-
posed, reaching in some cases to 10 or 12 per cent, of the bone earth, but
that recent bones contain as much as fossil and ancient bones do. In
recent bones, however, it cannot be so easily detected, until they have
been burned, the presence of gelatine seeming to impede the detection of
fluorine by the usual tests. Dr. G. Wilson has very recently shown that
fluoride of calcium is soluble in water to an extent quite sufficient to ac-
count for its very general diffusion. He has found it in sea- water, and in
all the springs which he has examined. Ihiubeny suggests that the pre-
sence of fluoride of calcium in bones may prevent any tendency to crystal-
lization, and thus confer on the bone additional toughness, — W, G.

120 THE ART OF CULTURE.

the hydrogen which is essential to the nouriphment of plants, if
presented to them in sufficient quantity.

When the soil is deficient in moisture, we observe a phenome-
non, which appeared quite inexplicable, before we understood
the importance of mineral matters, as means of nourishment to
plants. We see the leaves close to the soil (those which had
been first developed) lose their vitality, shrink and fall off,
after becoming yellow, without the apparent action of any inju-
rious cause. This phenomenon is not perceived, in this form, in
moist years, nor is it observed with evergreens, and only rarely
with those plants which throw out long deep roots ; it is observed
only in harvest and in winter with perennial plants.

The cause of this phenomenon is now quite apparent. The
matured leaves absorb continually from the air carbonic acid
and ammonia, which are converted into the constituents of new
leaves, buds, and twigs ; but this conversion cannot be effected
without the co-operation of alkalies and of other inorganic sub-
stances. When the soil is moist, these are constantly conveyed
to the plants, which retain their green color in consequence.
But in dry weather, the deficiency of water prevents them being
absorbed by the plant; and in consequence of this, they are
taken from the plant itself. The mineral ingredients in the juice
of the fully formed leaves are abstracted from them, and are
employed in the formation of the young sprout ; and when the
seeds become developed the vitality of the old leaf is completely
destroyed. These withered leaves contain mere traces of soluble
salts, while the buds and sprouts are remarkably rich in these
ingredients.

The reverse of this phenomenon is seen in the case of many
kitchen plants, when they are supplied with rich manure con-
taining an excess of mineral ingredients ; salts are separated
from the surface of their leaves, and cover them with a thin
white crust. In consequence of these exudations the plant be-
comes sickly, the organic activity of the leaves diminishes, the
growth of the plant is destroyed, and if this condition lasts, the
plant finally dies. These observations are best made on plants
with leaves of large dimensions, through which large quantities
of water are evaporated.

FERTILITY OF SOILS. 12\

This disease generally^ attacks turnips, gourds, and peas,
when the soil is drenched with sudden and violent rain, after
continued dry weather, at the time when the plants are near, but
have not attained maturity ; it is also necessary for its occur-
rence, that dry weather should again happen after the rain.

By the rapid evaporation of the water absorbed by the roots,
a laiger quantity of salts enters the plants than they are able to
use. The salts effloresce on the surface of the leaves, and
when they are juicy, act as if the plants had been treated with
solutions of salts, in greater quantity than their organism could
bear. Of two plants of the same kind the one nearest maturity
is most liable to this disease ; if the other plant has either been
planted at a later period, or if its development has been restrain-
ed, the causes, which exercised injurious effects upon the first
plant, accelerate the development of the latter. The germ
springing out of the earth, the leaf on coming out of the bud, the
young stem, and the green sprouts, contain a much larger quan-
tity of salts with alkaline bases and give ashes on incineration
much richer in alkaline ingredients, than parts of the matured
plant. The leaves, being the part in which the absorption and
decomposition of carbonic acid is effected, are much richer in
mineral ingredients than other parts of the plant.

The simple fact that a plant is restrained in growth by the
want of rain to convey to it alkalies, proves completely that these
alkalies play a most important part in vegetation.

Although it was found by Saussure that wheat before blossom-
ing yielded -j^-^, in blossom j^-^-ff, and after the ripening of the
seeds only half this quantity of ashes ; it cannot hence be con-
cluded that the ingredients of the soil present in the young and
growing plants, were again returned to the soil. Equal quanti-
ties of young plants yield twice the amount of ashes that matured
plants do ; but this evidently arises from the circumstance, that
new quantities of organic constituents are added to the carbon,
hydrogen, and nitrogen, previously existing in the young plant.
The amount of ashes remains the same in both plants, although
their relative proportions have become different.

We may feel assured that the alkalies contained in the vine,
in the potatoe, and beet, and found in the juices, united with tar-
7

122 THE ART OF CULTURE.

taric, citric, oxalic, and malic acids, are not merely present for
the purpose of being used in druggists* shops, or in our house^
hold, as acid or as neutral salts. These organic acids must be
necessary for the formation of certain constituents in the plants.

We have already come to the conclusion, that the carbon of
all plants is derived from carbonic acid ; tartaric, oxalic, citric
acid, (kc, must, therefore, obtain their carbon from the same
source. But, can we conceive that the carbon forms a direct
and immediate combination with hydrogen for the production of
substances so various as sugar, starch, woody fibre, resin, wax,
and oil of turpentine ? Is it not much more probable that the
conversion of the carbon of carbonic acid into the constituent of
a plant proceeds in a gradual manner ; that by the union of the
constituents of water with carbonic acid, a substance is formed,
becoming gradually poorer in oxygen ; and that the carbon as-,
sumes the form of oxalic, tartaric, or other organic acids, before
it is converted into sugar, starch, or woody fibre ?

According to this view, a ready and simple explanation is fur-
nished of the necessity of alkalic bases to vegetable life ; for
they are present for the purpose of effecting the conversion of
carbonic acid into a living part of a plant. The smallest parti-
cles of sugar, or of organic acids, when separated from plants,
follow their own peculiar attractions ; they form crystals, or they
follow the power which induces the cohesion of their atoms, but
still their carbon is capable of being converted into a constituent
of a living organ ; and, although sugar and tartaric acid have
been formed by vital agencies, they do not in themselves possess
any vital functions.

From the preceding part of this chapter it will be seen that
fallow is that period of culture when the land is exposed to pro-
gressive disintegration by the action of the weather, for the pur-
pose of liberating a certain quantity of alkalies and silica to be
absorbed by future plants.

The careful and frequent working of fallow land will accele-
rate and increase its disintegration ; for the purposes of culture it
is quite the same whether the land be covered with weeds, or
with a plant which does not extract the potash of the soil.

SCIENCE AND PRACTICE. 123

CHAPTER X.

On Fallow.

Agriculture is both an art and a science. Its scientific basit
embraces a knowledge of all the conditions of vegetable life, of
the origin of the elements of plants, and of the sources whence
they derive their nourishment.

From this knowledge fixed rules are formed for the practice
of the art, that is, for the necessity or advantage of all the
mechanical operations of the farm, by which the land is prepared
for the growth of plants, and by which those causes are removed,-
which might exercise an injurious influence upon them.

Experience acquired in the practice of this art can never stand
in contradiction to its scientific principles ; because the latter
have been deduced from all the observations of experience, and
are actually an intellectual expression of it. Neither can The-
ory ever stand in antagonism to Practice, for it is merely the
tracing back of a class of phenomena to their ultimate causes.

A field upon which we cultivate the same plants successively
for a number of years, may become unfertile for these plants in
three years ; whilst another field may last seven, another twenty,
and another one hundred years, without losing its fertility. One
field bears wheat but not beans ; another bears turnips but not
tobacco ; and a third yields rich crops of turnips, biit does not
bear clover.

What is the reason that a field loses gradually its fertility for
the same plant ? What is the reason that a certain kind of plant
flourishes on it, and that another fails ?

These questions are proposed by the Science of Agri-
culture.

What means are necessary to enable a field to sustain its fer-

124 ON FALLOW.

tility for the same plant, and to make it fit for the cultivation of
one, two, or for all plants ?

The latter questions are proposed by the art of Agri-
CTTLTURJS ; but they are not susceptible of solution by means of
the art.

When a farmer institutes experiments for the purpose of mak-
ing a field fertile for plants which it would not formerly bear,
the prospect of success must be small, unless he is guided by
scientific principles. Thousands of farmers try analogous expe-
riments in various ways, and the results of these constitute a
mass of experience, out of which a method of culture is finally
formed ; and this method suffices for a certain district. But the
same method fails with a neighboring district, or it may prove
actually injurious.

What an immense amount of capital and power is lost in such
experiments as these ! What a very different and much more
certain path does Science follow I It does not put us in danger
of failure, and it gives us the best security of success.

If the causes of failure or the causes of sterility of a soil for
one, two, or three plants be ascertained, the means of obviating
the sterility follow as a matter of course.

The methods of cultivating soils vary with their geological
characters. In basalt, grauwacke, porphyry, sandstone, lime-
stone, &c., let us suppose that there are present, in different
proportions, certain chemical compounds essential to the growth
of plants, and which must therefore exist in fertile soils; then
we are able to explain in a very simple manner the diflTerence
in the methods of culture ; for it is obvious that the soils formed
by the disintegration of the above rocks must vary in the pro-
portion of their essential constituents, just as the rocks themselves
vary.

Wheat, clover, and turnips, require certain constituents from
the soil ; and hence they cannot flourish in a soil from which
these are absent. Science enables us to recognise these neces-
sary constituents, by the analysis of the ashes of the plants ; and
if we discover the absence of these ingredients from the soil, the
cause of its sterility is obvious.

WEATHERING OF ORES. 125

The means of obviating this sterility follows from a knowledge
of its cause.

Empiricism ascribes all results to the art, that is, to the me-
chanical operations employed in cultivation, without inquiring
the causes upon which their use depends. But a knowledge of
these causes is of the highest importance ; for such knowledge
would prevent the lavish expenditure of capital and of power,
and would enable us to use them in the most advantageous man-
ner. Is it conceivable that the entrance of the ploughshare or
of the harrow into the earth — that the contact of iron with the
soil — can act as a charm to impart fertility ? No one can enter-
tain such an opinion ; and yet the causes of their action have not
yet been inquired into, and much less have they been explained.
It is quite certain that it is the great mechanical division, the
change and increase of surface, obtained by the careful plough-
ing and breaking up of the soil, which exercises so very favora-
ble an influence on its fertility ; but these mechanical operations
are only the means to attain that end.

Among the effects produced by time, particularly in the case
of fallow, or that period during which a field remains at rest,
science recognises certain chemical actions, which proceed unin-
terruptedly by means of the influence exercised by the constitu-
ents of the atmosphere upon the surface of the solid crust of the
earth. By the action of the carbonic acid and oxygen in the air,
aided by moisture and by rain-water, the power of dissolving in
water is given to certain constituents of rocks, or of their debris,
from which arable land is formed ; these ingredients, in con-
sequence of their solubility, become separated from the insoluble
constituents.

These chemical actions serve to explain the effects produced
by the hand of time, which destroys human structures, and con-
verts gradually the hardest rocks into dust. It is by their influ-
ence that certain ingredients of arable land become fit for assimi-
lation by plants ; and the object of the mechanical operations of
the farm is to obtain this result. Their action consists in acce-
lerating the weathering or disintegration of the soil, and thus
offers to a new generation of plants their necessary mineral con-
stituents, in a form fit for reception. The celerity of the disin-

.125 ON FALLOW.

tegration of a solid body must be in proportion to its surface ;
for the more points which we expose to the action of the destruc
tive agencies, the more rapidly will their effects be produced.

When a chemist subjects a mineral to analysis, in order to
break up the compound, that is, to give solubility to its constitu-
ents, he is obliged to perform the very tedious and difficult task
of reducing it to an impalpable powder. He separates the fine
dust from the grosser particles by means of a fine sieve, or by
elutrialion, and exerts his utmost patience to obtain a fine pow-
der ; because he is aware that the solution of the mineral will
be incomplete, and that all his operations will prove ineffectual,
if he be at all careless in this preliminary operation.

The influence of an increased surface upon the weathering of
a stone, or, in other words, on the changes which it suffers by the
action of the constituents of the atmosphere, and by water, is
very well pointed out in the interesting description given by Dar-
win of the gold mines at Yaquil, in Chili. The gold ores, after
being reduced to a very fine powder in mills, are subjected to a
process by which the particles of metal are separated from the
lighter parts of the ore. The particles of stone are carried away
by a stream of water ; while those of gold fall to the bottom.
The former are conducted into a tank, where they are permitted
to deposit. As the tank fills gradually, the fine mud is removed
from it, and is left in heaps to itself, that is, it is exposed to the
action of the air and of moisture. From the nature of the elutria-
tion to which it was subjected, the finely-divided ore can no longer
contain any salts, or soluble ingredients. Whilst it lay at the
bottom of the tank covered with water, and therefore excluded
from air, it suffered no change ; but when exposed to air, a pow-
erful chemical action ensues in the heaps, and this action is
recognised by the abundant efflorescence of salts, which cover
their surface, from the effects of disintegration. After the finely
divided ore has be^n exposed to the action of the weather for two
or three years, during which time it hardens, it is again elutri-
ated, and the processes of exposure and elutriation are repeated
six or seven times, new quantities of gold being obtained each
time, although in smaller proportions ; this gold is liberated by
the chemical process of weathering or of disintegration.

ACTION OF LIME. 121

The same chemical actions as those now described proceed in
our arable land, and it is to accelerate and increase these that we
employ the mechanical operations of culture. We renew the
surface of the soil, and endeavor to make every particle of it
accessible to the action of carbonic acid and of oxygen. Thus
we procure a new provision of soluble mineral substances, which
are indispensable for the nourishment and luxuriance of a new
generation of plants.

All cultivated plants require alkalies and alkaline earths,
although each of them may use different proportions of the one
or of the other ; the cereals do not flourish in a soil deficient in
silica in a soluble state.

Silicates, as they occur in nature, differ very materially in
their tendency to suffer disintegration, and in the resistance
which they offer to the action of atmospheric agents. The
granite of Corsica and the felspar of Carlsbad crumble into dust
in a space of time during which the polished granite of the Berg-
strasse does not even lose its lustre.

There are certain kinds of soil so rich in silicates prone to
disintegration, that every year, or every two years, a quantity of
silicate of potash is rendered fit for assimilation sufficient for the
formation of the leaves and stems of a whole crop of wheat. In
Hungary there are large districts of land, on which, since the
memory of man, corn and tobacco have been cultivated in alter-
nate years, without the restoration of the mineral ingredients
carried away in the corn and in the straw. There are other
fields, on the contrary, which do not yield sufficient silicate of
potash until after two, thrt-^, or more years.

Fallow, in its most extended sense, means that period of cul-
ture during which a soil is exposed to the action of the weather,
for the purpose of enriching it in certain soluble ingredients. In
a more confined sense, the time of fallow may be limited to the
interval inthe cultivation of cereal plants ; for a magazine of
soluble silicates and of alkalies is an essential condition to the
existence of such plants. The cultivation of potatoes or of tur-
nips during the interval will not impair the fertility of the field
for the cereals which are to succeed (supposing the supply of

138 ON FALLOW.

alkalies to be sufficient for both), because the former plants do not
require any of the silica necessary for the latter.

It follows from the preceding observations, that the mechanical
operations in the field are the simplest and most economical means
of rendering accessible to plants the nutritious matters in the soil.

But, it may be asked, are there no other means besides the
mere mechanical operations, of liberating the ingredients of a
soil, and of fitting them for reception by the organism of plants ?
There are such means, and one of the most simple and efficacious
of them is the practice employed in England for the last century,
of manuring soils with burnt lime.

In order to form a proper conception of the action of lime on
soils, we must remember the processes employed by chemists
to effect the speedy decomposition of a mineral, and to render
soluble its ingredients. In order to dissolve finely-pulverized
felspar in an acid, it would be necessary to expose it to continued
digestion for weeks, or even for months. But when the felspar
is mixed with lime, and is exposed to a moderately strong heat,
the lime enters into chemical combination with the constituents
of the felspar. A part of the alkali (potash) imprisoned in the
felspar is now set at liberty, and a simple treatment of the felspar
with acid, in the cold, now suffices to dissolve the lime and the
other constituents of the mineral. The silica is dissolved by the
acid to such an extent, that the whole assumes the consistence Oi
a transparent jelly.

Most of the silicates of alumina and alkalies, when mixed
with slacked lime and kept in continued contact in a moist state,
behave in a similar manner to felspar when heated with lime.
When a mixture of common clay, or of pipe-clay, and water, is
added to milk of lime, the whole becomes immediately thicker on
agitation. When they are left in contact for several months, it
is found that the mixture gelatinizes on the addition of an acid —
a property which the mixture of clay and water did not possess,
or only to a very small degree, before the contact with lime.
The clay is broken up by the union of certain of its constituents
with lime ; and, what is still more remarkable, most of the alka-
lies contained in it are set at liberty. These beautiful observa-
tions were first made by Fuchs of Munich ; and they have not

BURNING OF LAND. *79

only led to conclusions on the nature and properties of hydraulic
limestones, but, what is far more important, they have explained
the action of slacked lime upon soils, and they have thus furnish-
ed an invaluable means of liberating from the soil the alkalies
which are indispensable to the existence of plants.

In October, the fields in Yorkshire and Lancashire have the
appearance of being covered with snow. The soil for miles is
seen covered either with lime previously slacked, or with lime
that hfcs slacked itself by exposure to air. During the moist
months of winter, it exercises its beneficial influence on the stiff
clayey soils.

According to the old theory of humus, we ought to suppose
that burnt lime would exercise a very injurious influence on soils,
by destroying the organic matter contained in them, and by thus
rendering them unfit to supply a new vegetation with humus.
But, on the contrary, it is found that lime heightens the fertility
of a soil. The cereals require the alkalies and silicates liberated
by the lime and rendered fit for assimilation by plants. If there
be present decaying matter yielding to the plants carbonic acid,
their development may be favored by this means ; but this is
not necessary. For if we furnish to the soil ammonia, and to
the cereals the phosphates essential to their growth, in the event
of their being deficient, we furnish all the conditions necessary
for a rich crop, as the atmosphere forms an inexhaustible maga-
zine of carbonic acid.

In districts where fuel is cheap, an equally favorable influence
is exerted on clayey soils by the system of burning.

It is not very long since that chemists observed the remarka-
ble changes which take place in the properties of clay when it is
burned : these were first studied in the analysis of several sili-
cates of alumina. Many of them, which are not at all attacked
by acids in their natural state, acquire complete solubility when
they are previously melted by heat. To this class of silicates
belong pipe and potter's clay, loam, and the different varieties of
clay occurring in soils. In the natural state of clay, it may be
digested with concentrated sulphuric acid for hours, without dis-
solving in any appreciable quantity ; but when the clay is slightly
burnt (as is done, for example, in several alum works) it dissolves

^30 ON FALLOW.

in acids with great ease, while the silica is separated in its gela-
tinous and soluble form. Common potter's clay forms generally
very sterile soils, although it contains within it all the conditionis
for the luxuriant growth of plants ; but the mere presence of
these conditions does not suffice to render them useful to vegeta-
tion. The soil must be accessible to air, oxygen, and carbonic
acid, for these are the principal conditions to favor the develop-
ment of th6 roots. Its constituents must be contained in a state
fit to be taken up by plants. Plastic clay is deficient in all these
properties, but they are communicated to it by a gentle calcina-
tion.*

The great difference between burnt and unburnt clay may be
observed in places where burnt bricks are used for building.
In Flanders, where almost all the houses are constructed with
burnt bricks, the surface of the walls, after exposure for a few
days to the action of the weather, becomes covered with an efflo-
rescence of salts. When these salts are washed away by the
rain, a new efflorescence again appears ; and in some cases, as
the gateway of the fortress at Lille, this may be observed, even
though the walls have stood for centuries. The efflorescence
consists of carbonates and of sulphates with alkaline bases — salts
that are known to play a most important part in the economy of
vegetation. Lime exercises a striking effect upon these saline
efflorescences, for it may be observed, that they first appear in
those parts where the mortar and bricks come in contact.

It is obvious that mixtures of clay and lime contain all the con-
ditions necessary for the decomposition of the silicate of alumina,
and for rendering soluble the alkaline silicates. Lime dissolved
in water by means of carbonic acid acts upon clay in the same
way that milk of lime does. This fact explains the favorable
influence of marl upon most soils, marl being a clay rich in lime.
Indeed there are certain marly soils surpassing in fertility, for all
plants, soils of any other kind. Burnt marl must be in a very

* The author saw an example of this in the garden of Mr. Baker, at
Hardwick Court, near Gloucester. The soil consisted of a stiff clay, and,
from a state of complete sterility, had bien made remarkably fertile, by
simple burning. The operation, in this case, was carried on to a depth of
three feet, — certainly not an econcmical, although a completely successful
■experiment.

PHYSICAL STATE OF SOILS. 131

superior state for manure ; and this remark applies to all sub-
stances of a similar composition, — to the hydraulic limestones,
for example. By these the plants are furnished, not only with
alkalies, but also with silica, in a state fit for reception. Many
of the hydraulic limestones, or the natural cements, as they are
called, after being mixed in their burnt state with water, yield to
it, in a few hours, so much caustic alkali, that the water may be
employed as a weak ley for the purposes of washing.

The ashes of brown coal and of mineral coal are used in many
'listricts as excellent means of improving certain soils. Those
ashes are to be preferred that gelatinize on the addition of an acid,
or that become stony and hard after some time, like hydraulic
cement, when mixed with lime and water.

The mechanical operations of the farm, fallow, the applications
of lime, and the burning of clay, unite in elucidating the same
scientific principle. They are the means of accelerating the
disintegration of the alkaline silicates of alumina, and of sup-
plying to plants their necessary constituents at the commence-
ment of a new vegetation.

It must be distinctly understood, that the previous remarks
apply only to those fields which are in a favorable mechanical
state for the development of plants ; for this, in conjunction with
the other necessary conditions, has the greatest influence on fer-
tility. A stiff, heavy clayey soil offers too much resistance to
the spreading out and increase of the roots of a quick-growing
summer plant. It is obvious that such a soil will be rendered
more accessible to the roots, as well as to air and moisture, by a
simple mixture with quarz or with sand, and this may often prove
more effectual in improving it than the most diligent ploughing.
When we supply to a soil easily penetrable by the roots of plants,
as well as by air and moisture, in the form of ashes, the consti-
tuents that we re 1 loved in the crops, the soil will retain all its
original favorable physical state. In like manner, we can restore
the original chemical composition to stiff, heavy clay soils ;
but it is better for such soils to restore the necessary ingredients

IN THE FORM OF STABLE VARD MANURE, than tO do SO, ES in the

former case, by means of ashes. By the improvement of the
physical condition of the soil, its fertility is increased. In this
respect excrements are of very various values, although they may

1^^ ... ON FALLOW.

contain the same chemical constituents; thus sheep's dung ia
plose and heavy, while the dung of cows and of horses, especially
when mixed with straw, is light and pcrous.

In hot summers, accompanied by light and partial showers of
rain, porous soils of no great fertility yield often better crops
than richer stiff soils. The rain falling on the porous soil is im-
mediately absorbed and reaches the roots, whilst that falling on
the heavy soils is evaporated before it is enabled to penetrate
them.

A soil destitute of cohesion, like quick-sand, is not fitted for
the cultivation of plants in general. Finally, there are certain
kinds of soils which ought, from their chemical composition, to
be very fertile, but which, on the contrary, are sterile for many
kinds of plants : such soils are those that consist of clay mixed
with a large quantity of very fine sand. Such a soil converts
itself into a kind of thick mud after a heavy fall of rain, and thus
prevents all access of air, and it dries without much contraction.

If we were to apply, in all their extent, to porous, sandy, or
calcareous soils, or to a soil of the nature mentioned above, the
principles upon which depend the improvement of land by fallow,
we could not hope to obtain favorable results. A soil of great
porosity, through which water penetrates with great ease, and
which does not yield sufficient hold to the roots of plants, and also
a stiff soil, with its particles too finely divided, and of small fer-
tility on account of its physical properties, cannot be benefited by
the mechanical operations of the field ; for these are intended to
efliect a still further reduction of the particles.

The physical conditions essential to the fertility of a soil are
usually neglected in the calculations of the chemist, and thus
render a mere chemical analysis of very subordinate value ; for
the existence of all the mineral means of -lourishment in a soil
does not necessarily indicate its value. But when the chemical
is combined with the mechanical analysis* (for the latter of which
Mr. Rham has described an equally simple and convenient instru-
ment), then we are furnished with data upon which to form
accurate conclusions.

• The estimation of the unequal quantities of mixed ingredients, such
as of the coarse and fine sand, and of the clay and vegetable matter?

MINERAL SUBSTANCES IN ANIMAL BODIES. I3i

CHAPTER XI.

On the Rotation of Crops.

It has been shown, by accurate examinations of animal bodies,
that the blood, bones, hair, &c., as well as all the organs, contain
a certain quantity of mineral substances, without the presence of
which in the food, these tissues could not be formed.

Blood contains potash and soda in combination with phosphoric
acid ; the bile is rich in alkalies and sulphur ; the substance of
the muscles contains a certain amount of sulphur ; the blood
globules contain iron ; the principal ingredient of bones is phos-
phate of lime ; nervous and cerebral substance contains phos-
phoric acid and alkaline phosphates ; and the gastric juice
contains free muriatic acid.

We know that the free muriatic acid of the gastric juice and
part of the soda of the bile is obtained from common salt ;
and we are enabled, by the mere exclusion of this material
from food, to put an end to the digestive process and life of an
animal.

When a young pigeon is fed upon grains of wheat in which
phosphate of lime, the principal constituent of the bones, is defi-
cient, and when it is prevented receiving this substance from
other sources, its bones become thin and friable, and death ensues
if the supply of this mineral substance is still prevented.
(Choiset, Report to the Academy of Paris, June, 1842.) In
like manner, if we exclude carbonate of lime from the food of
fowls, they lay eggs without the hard exterior shell.

When a cow is fed upon an excess of roots, such as potatoes
and turnips, the same thing must happen to it, as in the case of
the pigeon cited above ; for these roots contain phosphate of
magnesia, and only traces of lime. Now, if we remove daily
from the same cow a certain amount of phosphate of lime in its

t34 ROTATION OF CROPS.

milk, without restoring this in the food, the lime will be obtained
from its bones, which will thus lose gradually their strength and
solidity, until they are no longer able to support the weight of the
body. But if we give to the pigeon as food barley or peas, and
to the cow barley-straw or clover, we will be able to sustain th -.
health of the animals ; for these materials abound in salts of
lime.*

Man and animals receive the constituents of their blood and of
their bodies from the vegetable world ; and an Infinite Wisdonv
has so ordained, that the life and luxuriance of plants is strictly
connected with the reception of the same mineral substances
that are indispensable for the development of the animal organ-
ism ; without the presence of the inorganic matters found in the
ashes of plants, the formation of the germ, leaves, blossoms, or
fruit, could not be effected.

The amount of nutritive matters in the different kinds of cul-
tivated plants is very unequal. The bulbous plants and roots
approach each other much more nearly in their chemical consti-
tuents than they do the seeds ; while the latter possess always
an analogous composition.

Potatoes, for example, contain from 75 to 77 per cent, of water,,
and from 23 to 25 per cent, of solid matter. By means of a
mechanical process, we may divide the latter into 18 or 19 parts
of starch, and 3 or 4 parts of a fibre resembling starch. Both of
these added together weigh nearly as much as the dry potatoe.
The two per cent, not accounted for consists of salts, and of the.
substance containing sulphur and nitrogen, known under the,
name of albumen.

Beet contains from 88 to 90 per cent, of water. Five-and- '■
twenty parts of dry beet contain very nearly the same elements

*The laborers. in the mines of South America, whose daily labor (per-
haps the most severe in the world) consists in carrying upon their shoul-
ders a load of earth of from 180 to 200 lbs. weight, from a depth of 450
feet, subsist only upon bread and beans. They would prefer to confine
themselves to bread, but their masters have found that they cannot work
80 much on this diet, and they, therefore, compel them, like horses, to eat
beans.- — {DarwirCs Journal of Researches.) Beans are proportionally
much richer in bone earth than bread.

CONSTITUENTS OF PLANTS. 135

as 25 parts of dry potatoes. In the beet there are 18 or 19 part?
of sugar and 3 or 4 parts of cellular tissue ; the two per cent,
not accounted for consist partly of salts, and the remainder of
albumen.

Turnips contain from 90 to 92 parts of water. From 23 to 25
parts of dry turnips contain 18 to 19 parts pectin, with very
little sugar, 3 or 4 parts cellular tissue, and 2 parts salts and
albumen. Sugar and starch do not contain nitrogen ; they exist
in the plant in a free state, and are never combined with salts, or
with alkaline bases. They are compounds formed from the car-
bon of the carbonic acid and the elements of water. In the
potatoe, these assume the form of starch, and in the turnip the
form of pectin.

In the seeds of cereals we find vegetable fibrin, a constituent
containing sulphur and nitrogen ; in peas, beans, and lentils, we
find CASEIN ; and in the seeds of oily plants, albumen and a
substance very analogous to casein. Casein and albumen have
the same composition as fibrin.

Vegetable fibrin is accompanied by starch in the seeds of the
cereals ; the latter body occurs with casein in leguminous
plants ; but, in the oily seeds, its place is supplied by another
body devoid of nitrogen, such as oil, butter, or a constituent
resembling wax.

It is obvious that we must furnish to plants the peculiar con-
ditions necessary for the development of these constituents,
according to our object in cultivation. In order to procure sugar
or starch, we must supply the plant with other materials than
we would do were our object to obtain the ingredients containing
sulphur and nitrogen.

In a hot summer, when the deficiency of moisture prevents
the absorption of alkalies, we observe the leaves of the lime-tree,
and of other trees, covered with a thick liquid containing a large
quantity of sugar ; the carbon of this sugar must, without doubt,
be obtained from the carbonic acid of the air. The generation
of the sugar takes place in the leaves ; and all the constituents
of the leaves, including the alkalies and alka ine earths, must
participate in effecting its formation. Sugar does not exude from'
the leaves in moist seasons ; and this leads us to conjecture, thatl

136 ROTATION OF CROPS.

the carbon which appeared as sugar in the former case would
have been applied in the formation of other constituents of the
tiee, in the event of its having had a free and unimpeded circu-
lation. When the soil is frozen in winter, there cannot be an
absorption of alkalies by the roots ; but notwithstanding this, it
cannot be doubted that during the day the evergreen and the
leaves of firs and pines must absorb continually from the air car-
bonic acid, which will be constantly decomposed by the action of
the light. When circulation is unimpeded, the carbon of this
carbonic acid may perhaps be converted into wood or into other
constituents of the plant ; but, in the absence of the conditions
necessary for this conversion, it may now secrete resin, balsam,
and volatile oils. In the generation of the sugar, or in that of
resin and volatile oil in the firs and pines, all the constituents of
the leaves must take part ; and hence we cannot suppose that
their alkalies, their lime, &c., are either accidental, or that they
are unnecessary to the exercise of this vital function.

For the conversion of the carbon or carbonic acid into sugar,
it is necessary that certain conditions exist in the plant itself, in
addition to the external circumstances (such as heat and air).

We furnish the conditions essential to the formation of starch,
or of sugar, when we supply to the leaves — that is, to the organs
destined for the absorption and assimilation of the carbonic acid
— their necessary constituents.

The sap of such plants as are rich in sugar or in starch, and
also the sap of most woody plants, contains much potash and
soda, or alkaline earths. We cannot suppose that these are mere
accidental ingredients ; on the contrary, we must believe that
they serve some purposes of the plants, and that they assist in
the formation of certain of their constituents. It has already
been mentioned, that they exist in the plants in a state of com-
bination with certain organic acids. These acids are so far
characteristic of certain genera, that they are never absent from
them. Hence the organic acids themselves must assist in some
of the vital functions. Now, when it is remembered that unripe
fruits, such as grapes, are unfit to eat on account of their acidity ;
that these fruits possess the same power as the leaves of absorb-
ing carbonic acid, and of giving off oxygen on exposure to light

FORMATION OF SUGAR. 137

(Saussure) ; and further, that the sugar increases on the diminu-
tion of the acid ; we can scarcely avoid coming to the conclusion,
that the carbon of the organic acid in the unripe fruit becomes a
constituent of the sugar when it is ripe, and that, in consequence
of the separation of oxygen and the assimilation of the constitu-
ents of water, the acid passes into sugar.

The tartaric acid in grapes, the citric acid in cherries and in
currants, the malic acid in summer apples, which ripen on the
trees, form in these plants the intermediate members of the pas-
sage of carbonic acid into sugar ; and when there is a deficiency
of proper temperature, or of the action of solar light, the changes
necessary for the conversion into sugar are not furnished, and the
acids remain.

In the fruit of the mountain ash, malic acid succeeds the tar-
taric acid at first present, or in other words, an acid poor in oxy-
gen succeeds one rich in that element ; afterwards the malic acid
in the berries disappears almost entirely, and in its place are
found gum and mucilage, neither of which formerly existed in
them ; and with the same reason that we consider that the carbon
of the tartaric acid forms a constituent of the succeeding malic
acid — and this few would be inclined to dispute — we suppose that
the carbon of the acids passes over into the sugar which succeeds
on their disappearance.

It surely cannot be supposed that a plant assimilates carbonic
acid, and that this carbonic acid is converted in the organism of
the plant into tartaric, racemic, and nitric acids, merely for the
purpose of being reconverted into carbonic acid.

If then the view be confirmed, that the organic acids in culti-
vated plants aid in the formation of sugar, it must be admitted
that they are of equal importance in the production of all other
non-azotized ingredients similarly composed. The formation of
starch, of pectin, and of gum, does not take place immediately, that
is, they do not arise at once from the union of the carbon of the
carbonic acid with the constituents of water ; but a gradual con-
version takes place, in consequence of the production of com-
pounds that are always poorer in oxygen, and always richer in
hydrogen. We cannot suppose that oil of turpentine could be

138

ROTATION OF CROPS.

formed without the existence of analogous intermediate members
of the series.

Now, if the organic compounds rich in oxygen, viz. the acids,
be the means of producing the compounds poorer in this element,
such as SUGAR, STARCH,- &c., then the alkalies and alkaline bases
must be looked upon as the conditions essential for the formation
of these non-azotized constituents, because the acids existing in
cultivated plants are generally in the form of salts and are rarely
free. An organic acid may perhaps be formed without the pre-
sence of these bases, but, in the absence of an alkali, or of a body
possessing an analogous action, sugar, starch, gum, and pectin,
cannot be formed in the organism of a plant. Sugar is not formed
in those fruits and seeds in which the organic acids are free, that
is, in which they do not exist as salts, as, for instance, citric acid
in the lemon, or oxalic acid in the chick-pea. It is only in plants'
containing the acids combined with bases in the form of soluble
salts, that sugar, gum, and starch, are produced.

It is a matter of little consequence what value is attached to
the opinion now given of the part taken by alkaline bases in the
process of vegetable life. But the following facts are of the great-
est significance and value to agriculture, namely, that the newly,
developed sprouts, leaves, and buds,* or in other words, those
parts of the plants possessing the greatest intensity of assimilation,
contain the greatest proportion of alkaline bases, and that the

* 1000 parts of Firwood gave 3'28 parts of ashes.
1000 «• Fir-leaves " 62-25
The ashes of the leaves of the fir amount to more than 20 times those in
the wood freed from its bark 100 parts of the former contain : — (Hert-
wig)

Alkaline carbonates >
Common salt - - >
Sulphate of Potash
Silicate of Potash
Carbonate of lime -

*« magnesia -

Phosphate of magnesia )

" lime )

Basic perphosphate of iron
Basic pnosphate of alumina
Silica - - - -

10-72

1-95
3-90

G3-32 ]
1-86

6-35

0-88

0-71

10-31

12'70 salts soluble in water.

86'30 compound « insoluble in water

IMPORTANCE OF ALKALIES. 139

plants richest hi sugar and in starch are no less distinguished for
their quantity of alkaline hases and of organic acids.

As we find sugar and starch accompanied by salts of an or-
ganic acid ; and as experience proves that a deficiency of alka-
lies causes a deficient formation of woody fibre, sugar, and starch ;
and that, on the contrary, a luxuriant growth is the consequence
of their abundant supply ; it is obvious that the object of culture,
viz. a maximum of crops, cannot be obtained, unless the alkalies
necessary for the transformation of carbonic acid into starch and
sugar are supplied in abundant quantity, and in a form fit for
assimilation by plants.*

* The acids — malic, tartaric, citric, oxalic, &,c. — are generated in the
organism of plants, and their carbon must be derived from carbonic acid.

In plants these acids are found combined with potash, lime, and mag-
nesia, in the form of salts, the smallest particles of which, when left to
themselves, follow their own attractions ; this is indicated by their crys-
tallization.

There is no doubt that these compounds do not possess orginic life, be-
cause the active power observed in them is not vitality, but cohesion.
The same must be the case with sugar, which crystallizes in a similar man-
ner.

We must presume that the smallest particles of the products formed
from carbonic acid are subject to the powers acting upon them in the living
plant, in the same way that a particle of carbonic acid is ; that, therefore,
the carbon of oxalic acid, tartaric acid, &c., must possess the power of
passing into a constituent of an organ endowed with life.

The conversion of organic acids into org ms may be followed with ease.

If we suppose that 1-2 equivalents of carbonic acid, in the presence of a
base, and by the action of light, loses the fourth part of its oxygen, in con-
sequence of the action of vitality upon its elements, then oxalic acid would
be produced. In its anhydrous state, we cannot conceive it to be formed
from carbonic acid in any other way.

C 1 2 O2 4 — 08=C 1 2 Oi 8=6 Eq. anhydrous oxalic acid.

Oxalic acid does not exist in an anhydrous state. Hydrated oxalic acid
contains one equivalent of water; the oxalates of potash, lime, and mag
nesia also contain water. Hydrated oxalic acid consists of —

C 1 2 Oi 8 +H6 06=C 12 Hfi O2 4=6 Eq. hydrated oxalic acid.

From this it may be observed that carbonic acid and hydrated oxalic acid
contain the same quantity of oxygen. We can, therefore, suppose that
hydrated oxalic acid has been formed from carbonic acid, to which a cer-
tain amount of hydrogen has been added.

By the continued action of the same agents a new quantity of oxygen
mifjiit become separated from the carbonic acid, in which case tartaric acid

140 ROTATION OF CROPS.

Every part and constituent of the body is obtained from plants.
By the organism of the plants, are formed those compounds which
serve for the formation of the blood ; there can be no doubt that

or malic acid would result. By the separation of 9 equivalents of oxygen,
tartaric acid would be produced ; the separation of 12 equivalents would
produce malic acid.

Hydrated oxalic acid C i 2 H g O ^ 4 — 0 9=Ci2H80i5 :=3 Eq. tartaric acid.
" " CisH6024—Oi2=Ci2H60i2=3Eq. malic acid.

By the simple separation of water from the elements of malic acid citric
acid is produced ; we know that we can produce, by means of heat, aco-
nitic acid from citric acid, and fumaric acid, or maleic acid, from malic
acid.

Malic acid C 1 2 H e 0 1 2 — HO=C 1 2 H 5 0 1 i =3 Eq. citric acid.
" C12 He Oi2— 3HO=Ci2 Hs O9 =3 Eq. fumaric acid.

Now we can view tartaric, citric, and malic acids as compounds of
oxalic acid with sugar, with gum, with woody fibre, or with the elements
of these :

Tartaric Acid. Oxalic Acid. Dry Sugar of Grapes.

2(Ci2H60i3) = CijOxs + C12H12O12
In such a manner, therefore, that the addition of new quantities of hydro-
gen would enable all these acids to aid in the formation of sugar, starch,
and gum. When this conversion is effected the alkalies in union with
the acids must of course be liberated, and they will thus be rendered capa-
ble of playing anew the same part. According to this view, it is quite
conceivable that one equivalent of an alkali may enable 10, 20, or 100
equivalents of carbon to pass into constituents of a plant; but the time
necessary to effect the transformation will vary according to the amount
of base present.

If a perennial evergreen, by the help of a certain quantity of alkali, is
able to assimilate a certain amount of carbon during the whole year, it will
be necessary to convey to a summer plant four times the quantity of alk^li,
in order to enable it to assimilate the same amount of carbon in one-fourth
the time.

Gay-Lussac first observed that by the contact of an alkali, at a high tem-
perature, with tartaric, citric, and oxalic acids, or sugar, woody fibre, &c.,
these substances were reconverted into carbonic acid.

This mode of decomposition is quite the reverse of that which takes
place in plants In the latter the elements of water unite with the com-
pound of carbon (carbonic acid); and oxalic acid, tartaric acid, &c., are
thus produced, in contsequence of a separatioi* or ox rcEiv. But in
the chemical process referred to, the elements of the water unite with the
elements of oxalic and tartaric acids, &c., and they are reconverted into
carbonic acid, in consequence of a separation of hydrogen.

Without the development of any gas, tartaric and citric acids, in contact
with alkali, even at a temperature of 400° F., are decomposed into oxalic

IMPORTANCE OF ALKALIES. 141

the nutritive parts of plants must contain all the constituents of
the blood, and not merely one or two of them.

It cannot be supposed that blood will be formed in the body of
an animal, or milk in that of a cow, if their food fail in even-ono
of the constituents necessary for the sustenance of the vital func-
tions. The compounds containing nitrogen and sulphur, as well
as the alkalies and phosphates, are constituents of the blood ; but
the conversion of the former into blood cannot be conceived with-
out the presence and co-operation of the latter.

According to this view, the power of any part of a plant to
support the life of an animal, and to increase its blood and flesh,
is in exact proportion to its amount of the organic constituents of
the blood, and of the materials necessary for their conversion into
blood — viz., of alkalies, phosphates, and ehlorides (common salt
or chloride of potassium).

It is highly worthy of observation, and of great significance to
agriculture, that the vegetable compounds containing sulphur and
nitrogen, which we have designated as the organic constituents
of the blood, are always accompanied, in the parts of the plants
where they occur, with alkalies and with phosphates. The juice
of potatoes and of beet contains vegetable albumen accompanied
by salts of alkaline bases, and by soluble phosphate of magnesia ;
in the seeds of cereals and of peas, beans, and lentils, there are
alkaline phosphates and earthy salts.

The seeds and fruits, which are richest in the organic con-
stituents of the blood, contain also the inorganic, such as the phos-
phates, in large quantity ; other parts of plants, as the potatoe, and
the various roots, which are proportionally so poor in the former
ingredients, contain a much smaller quantity of the latter.

The contemporaneous occurrence of both these classes of com-

and acetic acids. Anhydrous acetic acid contains carbon and the constitu-
ents of water, in exactly the same relative proportions as woody fibre (Pe-
ligot), which also yields acetic acid under similar circumstances.

These methods of decomposition have induced a distinguished French
chemist to assume the existence of ready-formed oxalic acid in tartaric
acid ; certainly its elements are present, besides those of a second body,
which, like sugar, gum, and woody fibre, may be viewed as a compouDd
of carbon with water. ■X'^^'^'i

143 ROTATION OF CROPS.

pounds is so constant, that it would be difficult to trace a case of
more intimate connexion. It is extremely probable that th«
origin and formation of the organic constituents of the blood in
the organism of plants is closely connected with the presence of
phosphates. It must be supposed that the organic constituents of
the blood will not be formed in a condition adapted for their con-
version into blood, without the presence of alkalies and of phos-
phates, which are found constantly to accompany them ; and this
will be the case, even although carbonic acid, ammonia, and sul-
phates as a source of sulphur, be presented to them in the most
abundant quantity. But, even on the assumption that they could
be generated in the organism of the plant, without the action of
these substances, we cannot suppose that they could be converted
into blood and flesh in the body of the animals, when the mineral
constituents of the blood were absent from the vegetable given
as food.

But independently of these views, a rational farmer must en-
deavor to effect the purpose desired, and in doing so he must act
exactly as if the presence of the inorganic constituents of blood
(the alkalies and phosphates) were indispensable for the produc-
tion of the organic constituents ; for he must furnish to the plants
all the materials necessary for the formation of the stem, leaves,
and seeds. If he is desirous of making his land yield a maximum
of blood and flesh, he must furnish to it in abundant quantity
those constituents which the atmosphere cannot yield.*

* When fresh arterial blood is evaporated to dryness* and incinerated,
ashes are obtained which yield to water salts of an alkaline reaction, but
not any alkaline carbonates, for no effervescence is occasioned by the addi
tion of an acid. These ashes consist of variable quantities of: —
Phosphates of the alkalies,
Phosphate of lime,
Phosphate of magnesia,
Basic perphosphate of iron
Common salt,
Sulphates of the alkalies.
The ashes of seeds contain : —

Bkans
Peas, (vicia fab*),
W\\\. Buchner.

Red

White

Wheat.

Wheat.

Rye.

Fresenius.

Will.

Fresenius.

Phosphate of potash

- 36-51

52-98

52-91

Phosphate of soda

- 3213

0-00

9-27

IMPORTANCE OF ALKALIES. 143

Starch, sugar, and gum contain carbon and the elements of
water, but they are never combined with alkalies, nor do they
contain phosphates. We can suppose that two specimens of the
same plant, when supplied with the same amount of mineral food,
may yet form very unequal quantities of sugar and of starch ;
and that two equal surfaces of land prepared in exactly the same
manner may bear two samples of barley, the one of which may
yield half or double the weight of the seeds that the other does.
But the excess of weight must depend upon the amount of unni-
trogenous ingredients, and not on the constituents containing sul-
phur and nitrogen ; for if the same quantity of the inorganic
constituents of blood be supplied to the soil, and if they enter into
the plants, a corresponding quantity of the organic constituents
of blood must be formed in the seeds, so that one cannot contain
more than the other. A difference in the result can happen only
when the one plant receives a less supply of nitrogen than the
other, in a given time ; for when there is a deficiency of ammo-
nia, a corresponding quantity of the inorganic constituents of the
blood is lefl unemployed.

When two species of plants are cultivated on a field of the
same nature throughout, that species which generates the greatest

Red
Wheat,
Fresenins.

ViTHITE

Wheat.
Will.

Rye.
Fresenius.

Peas.
Will.

Beans

{viciafaba)
Buchner.

Phosphate of lime - 3-35
Phosphate of magnesia - 19-61
Perphosphate of iron - 3 04
Sulphate of potasl^ . > rp_
Common salt - - j ^'^*^*'^'

506

32-96

0-67

5-21

26-91

1-88

2-98

10-77
13-78
2-46
9-09 >
3-96 5

9-35
19-11

1-84

Silicate of potash

Silica .... 0-15

0-30

0-34

1-11

's^ : : :] -»'>

8-03

0-50

In the above analyses, the phosphates of the alkalies in the peas and
beans are contained and calculated as tribasic salts ; those in the seeds of
the cereals, as bibasic. The ashes of the seeds cannot effervesce with
acids, because they do not contain an alkaline carbonate ; in this respect
they are similar to the ashes of blood ; and it may be observed that the
salts in both are quite the same. If the ashes either of blood or of the
seeds be exposed to air, they absorb caroonic acid and moisture ; the tri-
basic phosphate becomes bibasic, and the third atom of alkali is converted
into a carbonate.

144 ROTATION OF CROPS.

quantity of the organic constituents of the blood (compounds con-
taining sulphur and nitrogen) will remove from the soil the
greatest amount of inorganic constituents (phosphates).

The one plant will exhaust a soil of these ingredients, but it
may still remain in a good condition for a second kind of plant
requiring a smaller quantity of phosphates, and may even be fer-
tile for a third kind.

Hence it happens that the greater development of certain parts
of plants, such as the seeds, which contain much more of the or-
ganic constituents of the blood than any of the other parts, exhausts
and Removes fi'om the soil a much greater amount of phosphates
than would be done by the culture of herbaceous plants, tubers,
or roots, these being proportionally much poorer in the above in-
gredients. It is further evident, that two plants growing togethex
on the same soil will share its ingredients between them, if they
both require in equal periods equal quantities of the same con-
stituents. The ingredients taken up into the organism of one of
the plants cannot be used by the other.

If a given space of a soil (in surface and in depth) contains
inly a sufficient quantity of inorganic ingredients for the perfect
development of ten plants, twenty specimens of the same plant,
cultivated on this surface, could only obtain half their proper ma-
turity ; in such a case, there must be a difference in the number
of their leaves, in the strength of their stems, and in the number
of their seeds.

Two plants of the same kind growing in close vicinity must
prove prejudicial to each other, if they find in the soil, or in the
atmosphere surrounding them, less of the means of nourishment
than they require for their perfect development. There is no
plant more injurious to wheat than wheat itself, none more hurt-
ful to the potatoe than another potatoe. Hence we actually find
that the cultivated plants on the borders of a field are much more
luxuriant, not only in strength, but in the number and richness
of their seeds or tubers, than plants growing in the middle of the
•ame field.

The same results must ensue in exactly a similar manne?
when we cultivate on a soil the same plants for successive years,
instead of, as in the former case, growing them too closely to-

EXHAUSTION OF SOILS. 144

gether. Let us assume that a certain soil contains a quantity of
silicates and of phosphates sufficient for lOOO crops of wheat, then,
after 1000 years, it must become sterile for this plant. If we
were to remove the surface-soil and bring up the subsoil to the
surface, making what was formerly surface-soil now the subsoil,
we would procure a surface much less exhausted than the for-
mer, and this might suffice to supply a new series of crops, but
its state of fertility would also have a limit.

A soil will naturally reach its point of exhaustion sooner the
less rich it is in the mineral ingredients necessary as food for
plants. But it is obvious that we can restore the soil to its
original state of fertility, by bringing it back to its former com-
position ; that is, by returning to it the constituents removed by
the various crops of plants.

Two plants may be cultivated side by side, or successively
when they require unequal quantities of the same constituents,
at different times ; they will grow luxuriantly without mutual in-
jury, if they require for their development diffeueat ingredients
of the soil.

The experiments of Saussure, and of many other philosophers,
have shown that the seeds of beans, of Phaseo/us vulgaris, of peas,
and of garden cresses, germinate and even grow to a certain ex-
tent in moist sand or moistened horse-hair ; but when the mine-
ral substances contained in the seeds no longer suffice for their
further growth, then the plants begin to droop ; they may even
perhaps blossom, but they never bear seeds.

Wiegmann and Polstorf allowed plants of various kinds to
vegetate in a white sand previously treated with aqua regia, and
freed from the acid by careful washing,* Barley and oats grow-
ing in this sand, on being properly treated with water free from
ammonia, reached a height of lA foot; thoy blossomed, but did

*This sand contained in 1000 parts: — (Preisschrift, p. 28.;

Silica

-

,

- 97yoo

Potash

,

.

3-20

Alumina -

-

8-76

Peroxide of iron

-

315

Lime

-

• ,

4-84

Magnesia

8

009

148 ROTATION OF CROPS.

not come to seed, and withered after blossoming. Vetches reached
a height of ten inches, blossomed, and put out pods, but they did
not contain any seeds.

Tobacco sowed in the sand, developed itself at first in the usual
way, but from June to October the plants reached the height only
of five inches ; they had only four leaves and no stem.

The analysis of the ashes of these plants, and also the analysis
of their seeds, proved that although this sterile sand contained
such a small quantity of potash and of soluble constituents, still
it had yielded a certain quantity of these, and on this quantity the
growth of the leaves and of the stem depended ; but it was im-
possible that the plants could come to seed, because the con-
stituents necessary for the formation of the seeds were entirely
absent.

Phosphoric acid was detected in the ashes of most of the plants
growing in this sand, but its quantity corresponded only to that
introduced to the soil in the seeds themselves. In the ashes of
the tobacco plant, the seeds of which it is known are so small as
to contain scarcely an appreciable quantity of phosphoric acid,
not a trace of that acid could be detected.

What theory distinctly indicated as the cause of the sterility
of this sand, the experiments of Wiegmann and Polstorf com-
pletely established. They took the same sand and prepared from
it an artificial soil by the addition of salts manufactured in a
laboratory (see Appendix) ; they then sowed in this soil the same
])lants, and saw that they flourished in the most luxuriant man-
ner. The tobacco became three feet in height, and put forth
many leaves ; on the 25th of June it began to blossom, and on the
10th of August obtained seeds, from which on the 8th of Septem-
ber ripe seed capsules with complete seeds were taken. In ex-
actly the same way, barley, oats, buck-wheat, and clover grew
luxuriantly, blossomed, and yielded ripe nnd perfect seeds.

It is quite certain, that tiie growth of these plants in the for-
merly sterile sand, depended upon the salts added to it. An equa.
fertility for all plants is given to this artificial soil by the addition
of certain substances which are absolutely necessary for the life
of the plants, because they are present in the matured plant, and
in its stem, leaves, and seeds.

RESTORATION OF FERriLITY. U7

Thus we are in a position to give to the most sterile soil a state
of the greatest fertility for all plants, if we furnish to it the con-
stituents which they require for their growth. It would, indeed,
neither repay the labor nor the expense to render fertile on those
principles an absolutely sterile soil. But in our ordinary arable
soils, which contain already many of these constituents, it suffices
to supply the absent ingredients, or to increase those which are in
deficient quantity. At the same time, by the art of farming, the
soil must be put into a proper physical state, by which it is ren-
dered accessible to moisture and to rain, and is fitted to enable
the plants to appropriate these ingredients of the soil.

Different genera of plants require for their growth and perfect
maturity, either the same inorganic means of nourishment, al-
though in unequal quantities and at different times, or they re-
quire different mineral ingredients. It is owing to the difference
of the food necessary for the growth of plants, and which must
be furnished by the soil, that different kinds of plants exert mutual
injury when growing together, and that others, on the contrary,
grow together with great luxuriance.

Very little difference is observed in the composition of the ashes
of the same plants, even although they have grown on different
soils. Silica and potash form invariable constituents in the straw
of the Graminese ; and, in their seeds, there is always present
phosphate of potash and phosphate of magnesia. A large quan-
tity of lime occurs in the straw of peas and in clover. We know,
further, that in certain kinds of plants, the potash is replaced by
soda, and the lime by magnesia.

It has been shown by the experiments of Boussingault,* that
the five following crops grown in succession on an equal surface
of the same field once manured, removed from the soil : —

Ingredients of the soil.

1 Year crop of Potatoes (tubers without herb) - - 2168 lbs.

2 " " Wheat (straw and corn) - - - - 3710 "

3 " " Clover G200 "

4 « « CWheatf 48S-0 "

( Fallow Turnips lOSS "

4 " " Oats (corn and straw) ... - 2150 "

«f ^Annales de Chimie et de Physique, t. i , p. 242
t On a system of alternate crops.

ii ROTATION OF CROPS.

' ■ »

Ingredients of the soil

By a crop of Beetroot* (roots without leaves) - - - 3996 "

" " Peas (peas and straw) olS'O "

"Rye 2S4-6 "

" •• Helianthus tuberosus 660*0 "

These numbers express the quantities (tt inorganic substances
removed from the same soil by different plants, and carried away
with the crops. They, therefore, prove that different plants take
up into their organism, unequal weights of these ingredients of
the soil. It is shown by a further consideration of the composi-
tion of these ashes, that they differ essentially from each other
with respect to their quality.

One thousand parts of beet, turnips, or potatoes, yield by in-
cineration 90 parts of ashes; the latter are easily fusible, and,
contain a large quantity of carbonate of potash, and of salts with
alkaline bases. Of these 90 parts, 75 parts are soluble in cold
water.

Two thousand parts of dry fern yield also 90 parts of ashes ;
but of these 90 parts none, or only a trace, is soluble in water
(Berthier).

The ashes of wheat, barley, pea, and bean straw, differ in like
manner in their composition. Equal quantities of their ashes
contain very unequal amounts of ingredients soluble in water.
There are certain ashes of plants wholly soluble in water;
others are only partially soluble, while certain kinds yield only
traces of soluble ingredients.

When the parts of the ashes Insoluble in water are treated
with an acid (muriatic acid), this residue, in the case of many
plants, is quite soluble in the acids (as for instance the ashes of
beet, turnips, and potatoes) ; with other plants, only half the
residue dissolves, the other half resisting the solvent action of the

* In the above five-yearly rotation, wheat was introduced twice. In the
second year the crop of wheat removed from the soil 371 lbs. and in the
fourth year 45S lbs. of inorganic substances. This difference depends upon
the unequal quantities of straw and corn in the crops of the two years.
The weight of the straw and corn of one year was 8790 lbs., in the other
year it amounted to 10,858 lbs. The relative proportion of their ashes if
exactly the same.

PLANTS DISTINGUISHED BY CERTAIN SALTS. 149

acid ; while in the case of certain plants only a third, or even
.ess of the residue is taken up by tlie acid.

Tlie parts of the ashes soluble in cold water consist entirely
of SALTS WITH ALKALINE BASES (poTASH AND soda). The ingre-
dients soluble in acids are salts of lime and magnesia ; and
the residue insoluble in acids consists of silica.

These ingredients being so different in their behavior to watei
and to acids, afford us a means of classing the cultivated plants
according to their unequal quantity of these constituents. Thus
POTASH PLANTS are those the ashes of which contain more tlian
half their weight of soluble alkaline salts ; we may designate as
LIME PLANTS, and as silica PLANTS, those in which lime and silica
respectively predominate. The ingredients thus indicated are
those which form the distinguishing characteristics of the plants
which require an abundant supply of them for their growth.

The POTASH PLANTS include the chenopodia, arrach, worm-
wood, 6zc. ; and amongst cultivated plants, the beet, mangel-
wurzel, turnip, and maize; Tlie lime plants comprehend the
lichens (containing oxalate of lime), tlie cactus (containing crys-
tallized tartrate of lime), clover, beans, peas, and tobacco.
Silica plants include wheat, oats, rye, and barley.*

Salts of Potash S;ilts of Lime

an«l Soila. luiii Magnesia. Silica.

[ Oatstraw with seeds (1) - -34 00 4 00 02 00

Silica j Wheat-straw (2) - - - - 22 00 720 G105

Plants. 1 Barlev-straw with seeds (1) - lO'OO 2570 5503

l^Rve-straw (3) 18'65 10*52 03-89

* The ashes of good meadow-hay (consisting; of a mixtare of the ashes
of potash, lime, and silica plants), gave in 100 parts — (Haioi.ev) :

Silica GO- 1

Phosphate of lime - - - - lOL

Phosphate of peroxide of iron - - 50

Lime - - - - - - - 2-7

Magnesia - - - - - - 8'6

Gypsum - - - - - -1'2

Sulphate of potash - - - - 2*2

Chloride of pota-ssium - - - - 1'3

Carbonate of soda - - - - 2*0

Lobs 08

190 ROTATION OF CROPS.

Salts of Potash Salts of Lime
and Soda. and Magnesia. Silica.

Tobacco (Havannah) (4) - - 2434 6744 8-30

(Dutch) (4) - - - 23-07 62-23 15-25

Lime
Plants. '

(grovvn in an arti- ) _ ^ ^g.^^

I soil (1) )

ficial soil (1)

12-00

Pea-straw (4) 27 82 63-74 7-81

Potatoe-herb (5) 4 20 59-40 36 40

Meadow-clover (1) - - - - 39 20 56-00 4-90

(Maize-straw (2) 71 00 6 50 18*00

Turnips ....... 81-60 18-40

Beetroot (6) 88 00 12-00

Potatoes (tubers) (6) - . - 85*81 14-19

tHelianthus tuberosus (7) - -84-30 1570*

This classification, however, is obviously only a very general
one, and pennit-s division into a great number of subordinate
classes ; particularly with respect to those plants in which the
alkalies may be replaced by lime and magnesia. As far as we
are authorized to judge by our present knowledge, a substitution
of soda for potasli lakes place in our cultivated plants ; but it has
not yet jjcen oi)served, tliat in these plants the alkalies can be
replaced by lime.

The potutoe ])lant belongs to the lime plants, as far as regards
the ingredients of its leaves, but its tubers (which contain only
traces of lime) belong to the class of potash plants. With
reference to tlic siliceous plants this difference of their parts is
very marked.

Barley must be viewed as a lime plant, when compared with
oats or with wheat, in reference to their ingredients soluble in
muriatic acid ; but it would be considered as a siliceous plant, if
viewed only in reference to its amount of silica. Beet-root con-
tains phosphate of magnesia, and only traces of lime ; while the
turnip contains phosphate of lime and only traces of magnesia.

"When we take into consideration the quantity of ashes, and
their known composition, we are enabled to calculate with ease,
not only the particular ingredients removed from a soil, but also

In the above analysis, the figures represcrit the chemists as under:—

(1) Wiegmann and Polstorf. I (5) Berth i<»r and Braconnot.

(2) Saussure. | (6) Hruschaner.

(3) Fresenius. (7) Braconnct.

(4) Hertwig.

EXHAUSTION OF SOILS BY CERTAIN PLANTS. 151

the degree in which it is exhausted of these by certain species
of plants belonging to the potash, lime, or siliceous plants.
This will be rendered obvious by the following examples.

A soil, consisting of four Hessian acres, has removed from it
by a crop of —

Salts of potash Salts of lime, magnesia,

and soda. and jKjroxide of iron. Silica,

lbs. lbs. lbs. lbs. lbs.

ixri +( In straw 95"31 > ,oA.r, 34"75 > ai-rr n^n.nr

^^ ^^"^* I In corn 35-20 ^^^ ""^ 32-80 J ^^ ^^ 260-05

n.^c ( Tn straw 150-40 > .nQ.in 354-&0 > „_, .„ ,„ ^_

^'-^^ ( In corn 44 02 \ ^^^ "^^ 16-6S 5 ^'^-^^ ^^^®

C In straw 40-73) ^.^ „^ 36 00)

^y*^ ^ In corn 4-2-05 5 ^^'^^ 21-82 5 ^

Beet-root, without leaves - - 36100 3784

Heliiuithus tuberosus - - - 556-00 104-00

The same surface is deprived by these crops of the following
quantity of phosphates* —

* In the above numbers we have not an exact, but an approximate, pro-
portion of the ingredients of the soil removed by the various crops. The
analyses of the ashes have been used, as far as they are already made and
known. The analysis of the ashes of the seeds and of the straw of wheat
is by Saussure ; that of pea-straw by Hertwig ; that of peas by Dr. Will ;
that of the ashes of the straw and seeds of rye by Dr. Fresenius, of the beet-
root by Hruschauer, and of Helianthus tuberosus by Braconnot. Exact
and trustworthy results can only be obtained by estimating the ashes of
the crops grown on a given surface, and by subjecting these ashes to
analysis ; and not as in the above cases, in which the analyses were made
upon the ashes of plants grown under different circumstances and in differ-
ent situations. Boussingault, for example, obtained from pea-straw (from
a crop heavily manured) 11-2 per cent, of ashes ; Saussure obtained only 8
per cent, (in straw with seeds), and Hertwig only 5 per cent. These
numbers change the absolute quantities, but have little or no influence 0;n
the relative proportions.

The analyses by Sprengel of the ashes of vai.ous plants are quite inexact,
and do not merit the slightest confidence. The ashes of the seeds of
wheat, of peas, of beans, rye, fcc, consist of phosphates, without any mix-
ture of carbonic acid ; these ashes do not contain silica. But Sprengel
finds in peas 18 per cent, and in rye 15 per cent, of silica. The ashes of
the seeds of rye contain 48 per cent., those of peas 34*23 per cent., of an-
hydrous phosphoric acid; but Sprengel finds in peas only 4 per cent., in
rye 8 per cent., of phosphoric acid. It is worthy of observation, that all
the bases in the ashes of peas are present as tribasic phosphates, while ia
the ashes of rye and ol wheat, they exist as bibasic salts.

159 ROTATION OF CROPS.

Helanthns
Peas.* Wheat. Rye. tuberosus. Tamipa.f

117 112-43 77-05 122 37-84

According to the preceding views, plants must obtain from
the soil certain constituents, in order to enable them to reach
perfect maturity — that is, to enable them to bear blossoms and
fruit. The growth of a plant is very limited in pure water, in
pure silica, or in a soil from which these ingredients are absents
If there be not present in the soil alkalies, lime, and magnesia,
the stem, leaves, and blossoms of the plants can only be formed
in proportion to the quantity of these substances existing as a
provision in the seed. When phosphates are wanting, the seeds
cannot be formed.

The more quickly a plant grows, the more rapidly do its
leaves increase in number and in size, and therefore the supply
of alkaline bases must be greater in a given time.

As all plants remove from the soil certain constituents, it is
quite obvious that none of them can render it either richer or
more fertile for a plant of another kind. If we convert into
arable land a soil which has grown for centuries wood, or a
vegetation which has not changed, and if we spread over this
soil the ashes of the wood and of the bushes, we have added to
that contained in the soil a new provision of alkaline bases, and
of phosphates, which may suffice for a hundred or more crops of
certain plants. If the soil contains silicates susceptible of disin-
tegration, there will also be present in it soluble silicate of
potash or soda, which is necessary for the rendering mature the
stern of the siliceous plants ; and, with the pliosphates already
present, we have in such a soil all the conditions necessary to
sustain uninterrupted crops of corn for a series of years.

If this soil be either deficient or wanting in the silicates, but
yet contain an abundant quantity of salts of lime and of phos-
phates, we will be enabled to obtain from it, for a number of years,
successive crops of tobacco, peas, beans, &c., and wine.

But, if none of the ingredients furnished to these ulants be again
returned to the soil, a time must come when it can no longer

♦Heavily manured. t Heavily manured.

EXHAUSTION OF SOILS. K^3

furnish these constituents to a new vegetation ; when it must
become completely exhausted, and be at last quite sterile, even
for weeds.

This state of sterility will take place earlier for one kind of
plant than for another, according to the unequal quantity of the
different ingredients of the soil. If the soil is poor in phosphates
out rich in silicates, it will be exhausted sooner by the cultivation
of ^♦'heat than by that of oats or of barley, because a greater
quantity of phosphates is removed in the seeds and straw of one
crop of wheat, than would be removed in three or four crops of
oarley or of oats.* But if this soil be deficient in lime, the bar-
ley will grow upon it very imperfectly.

It is owing to the deficiency of these salts, so indispensable to
the formation of the seeds, that it happens, however abundant may
be the quantity of silicates, that in one year v.e may obtain nine
times, in a second thrice, in a third twice as much corn as may
grow on the same soil in another year.

In a soil rich in alkaline silioitos, but containing only a limited
supply of phosphates, the period of its exhaustion for these salts
will be delayed if we alternate with the wheat plants which we
cut before they have come to seed ; or, what is the same thing,
with plants that remove from the soil only a small quantity of
phosphates. If we cultivate on this soil peas or beans, these
plants will leave, after the removal of the crop, a quantity of si-
lica in a soluble state sufficient for a Gucceeding crop of wheat ;
but they will exhaust the coil of phosphates quite as much as
wheat itself, because the seeds of both require for their maturity
nearly an equal quantity of these salts.

We are enabled to delay the period of exhaustion of a soil of
phosphates by adopting a rotation, in which potatoes, tobacco, or
clover, are made to alternate with a white crop. Tlie seeds of
the plants now named are small, and corAmn proportionally only
minute quantities of phosphates ; their rocts and leaves, also, do
not require much of these salts for their maturity. But it must

* The weight of the ashes of a crop ct the seeds of wheat is to that in a
rrop of oats as 34 : 42'6, the pho3}.iliitp.s contained in them as 26 : 10 ; th«
phosphates of the straw not being included in the calculation.
8*

154 ROTATION OF CROPS.

be remembered, at the same time, that each of these has ren-
dered the soil poorer, by a certain quantity of phosphates. By
the rotation adopted, we have deferred the period of exhaustion,
and have obtained in the crops a greater weight of sugar, starch,
&;c., but we have not acquired any larger quantity of the con-
stituents of the blood, or of the only substances which can be con-
sidered as properly the nutritious parts of plants. When the soil
is deficient in salts of lime, tobacco, clover, and peas will not
flourish ; whilst, under the same conditions, the growth of beet-
root or turnips will net be impeded, if the soil, at the same time,
contain a proper quantity of alkalies.

When a soil contains silicates not prone to disintegrate, it may
be able, in its natural state, to liberate by the influence of the at-
mosphere, in three or four years, only as much silica as suffices ,
for one crop of wheat. In this case, such a crop can only be
grown on it in a three or four years' rotation, assuming that the
phosphates necessary for tiie formation of the seeds exist in the
soil in suflicient quantity. But we can shorten this period by

. working well the soil, and by increasing its surface, so as to make
it more accessible to the action of the air and moisture, in order
to disintegrate the soil, and to procure a greater provision of solu-
ble silicates. The decomposition of the silicates may also be ac-
celerated by the use of burnt lime ; Inr it is certain that, although
all these means may enable us to ensure rich crops for a certain

, period, they induce, at the same time, an earlier exhaustion of
the soil, and impair its natural .stale of ftrtility.

If the proportion of ailfali and of silica liberated from the soil
in the course of three or four years be sufficient only for one crop
of wheat, we cannot in the interval, without injury to this crop,
cultivate on the same soil any other plant ; because the alkalli
necessary for the grovv th of the latter cannot be applied to the use
of the wheat.

By examining the known proportion of alkali and of silica
liberated by the disintegration of the silicates in their conversion
into clay, and by the weathering of the latter itself,* we find that,

*■ •One equivalent of silica is libcratotl for every equivalent of potash
•eparftted from the constituents of an equivalent of felspar. In the straW

WEATHERING OF SILICATES. 155

for a given quantity of silica rendered soluble, a much larger
amount of alkali is liberated than corresponds to the proportion in
which both arc taken up into the straw of the cereals.

During the time of fallow, which in this case must elapse be-
fore two crops of wheat can be obtained, we may employ the ex-
cess of alkalies in the culture of other plants requiring salts with
alkaline bases without silica. Between these crops, therefore, we
may grow mangel wurzel, or even potatoes, if we remove only
the tubers of the latter, and allow the plant itself, which contains
much silica, to remain on the field.

In the preceding remarks, we have considered the changes in
the nature and composition of a field on which a rotation of culti-
vated plants has been carried on for a series of years. If this
field contain an ordinary proportion of alkaline silicates, clay,
lime, and magnesia, it will possess an almost inexhaustible pro-
vision of alkalies, alkaline earths, and silica ; with this diiference,
however, that they are not all in a fit state to be used by (he plant
at the same time. By the mechanical operations of the farm, and
by chemical means (by the use of lime, &c.), we may shorten
the time in which these obtain a form fitted for the vital functions
of the plant ; but these matters do not suffice for its complete
maturity.

When phosphates and sulphates are absent from the soil, the
plants growing on it cannot form seeds, because all seeds, without
exception, contain compounds in which phosphoric acid and sul-
phur are invariable constituents. Although all the other ingre-
dients of plants be present in superabundance, the soil will become
completely sterile, when the period arrives at which it can no
longer furnish phosphates or sulphates to a new vegetation.

We must suppose that, for the formation of the stem and herb,
for the fixation of carbon, and for the production of sugar, starch,
and woody fibre, a certain amount of alkalies (in the case of the
potash -plants), or an equivalent of lime (in the case of the lime-
plants), is necessary. But we must bear in mind, at the same
time, that the constituents of blood can be formed in the organism

of wheat, oats, and rye, for 10 eq. of silica, there is only 1, or at tbe mart,

a eq in combination with alkalies.

156 ROTATION OF CROPS.

of the plant only in quantity corresponding to that of the phos-
phates, however abundantly ammonia or carbonic acid may be
supplied. The production of the constituents of the juice con-
taining sulphur and nitrogen is inseparably connected with the
presence of these salts.

Every soil upon which a weed attains maturity is fitted for
culture if that weed yields, on incineration, alkaline ashes.

The alkalies of these ashes arise from silicates, so that in addi-
tion to the alkalies, soluble silica must exist in the same soil.
Such a soil may contain a quantity of pbosphates of lime and
magnesia sufficient for potatoes and turnips, without on that ac-
count being rich enough for crops of wheat.

These considerations must show the great importance which
onght to be attached to phosphates in the practice of agriculture.
These salts are present in the soil only in small quantity, and
therefore the greater attention should be paid to prevent its ex-
haustion.

In the limited but enormous extent of the ocean, whole worlds
of plants and animals succeed each other. A generation of these
animals obtain all their elements from plants, and the constituents
of the organs of the animal after death assume their original form,
and serve for the nourishment of a new generation of animals.

The oxygen employed by the marine animals in the process of
respiration, and removed from the air, dissolved in the water
(this air contains from .32 to 33 volumes per cent, of oxygen, while
atmospheric air contains only 21 per cent.), is restored again to
the water, by the vital processes of marine plants. In the pro-
ducts of the putrefaction of the carcases of the dead animals,
their carbon is converted into carbonic acid, their hydrogen into
water, and their nitrogen assumes again the form of ammonia.

Thus, we observe that in the sea, a perpetual circulation takes
place, without the accession or removal of an element, and this
circulation is unlimited in its duration, allhou^h it may be in its
extent, by the finite quantity of nour":;r.n;<:n1 conteined in plants
in a limited space.

Willi respect to niarlre ]-Iarttr:, the.e CAnnct iio any discussion
us to their receiving food by their roots in the form of humus.
What nourishment indeed can the thick roots of the giant sea-

FOOD OF MARINE PLANTS. 157

woed draw from a naked rock, the surface of which does not suffer
the slightest change — a plant which reaches a height of 360 feet
(Cook), and one of which, with its leaves and twigs, affords nour-
ishment to thousands of marine animals. These plants require
obviously only a fastening point in order to prevent a change of
place, or an arrangement by which their small specific weight is
compensated ; they live in a medium which conveys the neces-
sary nourishment to all their parts. Sea-water does not only con-
tain carbonic acid and ammonia, but also phosphates, and earthy
and alkaline carbonates, salts invariably found in the ashes of
marine plants, and indispensable for their growth.

All our knowledge tends to prove that the conditions necessary
for the existence and duration of marine plants are the same as
those upon which the existence of terrestrial plants depends.

But terrestrial plants do not live like marine plants, in a me-
dium containing all their elements, and surrounding every part
of their organism ; but their existence depends upon two media,
the one of which, the so[L, contains constituents which are absent
from the other, the atmospheue.

How is it possible, we may well ask, that there ever could
have been a doubt as to the part wliich the constituents of the soil
took in the growth of the vegetable world ? Yet, there was a
time when it was considered that the mineral constituents of
plants were not necessary and essential to their existence !

The same circulation exists on the surface of the earth as in
the sea ; there is an unceasing change — a perpetual destruction
and re-establishment of equilibrium. Practice in agriculture has
taught us that the amount of vegetable matters on a given sur-
face increases with the supply of certain substances, which were

ORIGINAL constituents OF THE SAME SURFACE OF THE SOIL, and

had been removed from it by means of plants. The excrements
of men and of animals arise from plants ; they are exactly the
materials which, during the life of the animal, or after its death,
obtain again the same form that they possessed as constituents of
the soil.

We know that the atmosphere does not contain these materials,
and that it does not replace them ; we know further that, by their
removal from the soil, an inequality of production is occasioned,

.58 ROTATION OF CROPS.

and, finally, even a want of fertility ; but that, by the restoration
of these materials, the fertility may be sustained, and even in-
creased .

After so many striking proofs respecting the origin of the con-
stituents of plants and of animals, and of the use of alkalies, of
phosphates, and of lime, can we entertain the sliglitest doubt of
the principles upon which a rational system of agriculture must
depend ? .^

Does the art of farming, then, depend upon anything else than
the restoration of a disturbed equilibrium ?

Is it conceivable, that a rich fertile land, with a flourishing
trade, which has for centuries exported the products of its soil in
the form of cattle and of corn, can retain its fertility, if the same
trade do not restore to its land, in the form of manure, the con-,
stituents abstracted from it, and which cannot be replaced by the
atmosphere ? In such a case, would not the same fate await this
land as that which befel Virginia, upon the soil of which wheat
and tobacco can no longer be cultivated ? .^

In the large towns of England, the products of English as well
as of foreign agriculture are consumed ; and to supply this great
consumption, the constituents of the soil necessary to the plants
are removed with them, from an immense surface of land, to
which they are not again returned. The domestic arrangements
peculiar to the English render it difficult, perhaps even impossi-
ble, to collect the immense quantity of phosphates (the most im-
portant ingredients of the soil, although present in it in small
quantity), which are daily sent into the rivers in the form of urine
and of solid excrements. We have seen ujwn the fields of Eng-
land exhausted of their phosphates, the most beneficial effects pro-
duced upon the crops by the introduction of bones (phosphate of
lime) from the Continent ; in some cases, the crops on the soil
were doubled by the use of this manure, as if by a charm.

But if this exportation of bones be continued on the same scale
as at present, the German soil will become gradually exhausted ;
and the loss will be perceived to be greater than at first is ap-
parent, when it is considered that a single pound weight of bones
contains as much phosphoric acid as a whole hundred- weight
of corn.

WASTE OF MANURE IN ENGLAND.

Thousands of hundred weights of phosphates flow annually into
the sea with the Thames, and with other of the British rivers.

Thousands of hundred-weights of the same materials, arising
from the sea, annually flow back again into that land in the form
of guano.

In the alchemistical era, the imperfect knowledge of the pro-
perties of matter gave rise to the supposition, that metals, such s
gold, could be developed by seeds. Crystalline forms, and the
ramifications which they assume, appeared to alchemists to be the
leaves and branches of metallic plants, and their great endeavors
were to find an earth fitted for the peculiar growth and develop-
ment of their seeds. Without there being any apparent nourish-
ment given to a seed, it was seen to grow to a plant, which put forth
blossoms and seeds. This led to the belief, that could the seeds
of metals be procured, similar hopes of their reaching maturity
might be entertained.

Such ideas could only belong to a time when scarcely anything
was known of the nature of the atmosphere, and when there was
not a conception of the part taken by the earth and air in the vital
processes of plants.

The chemistry of the present day exhibits the elements of
water ; it can even prepare this water with all its properties from
their elements ; but it cannot manufacture these elements — it can
only prepare them from water. The newly-formed water, which
has been artificially prepared, was water previously to the separa-
tion of its elements.

Many of our farmers, like to these alchemists of old, in search-
ing after the philosopher's stone, look now to find the wonderful
seeds ; for they expect that tiieir land should bear a hundred-
fold, without supplying to it any food, even although this land
is scarcely rich enough to bear the plants usually cultivated
on it !

The experience of centuries or of thousands of years is not
sufficient to protect them from the new fallacies which are con-
stantly arising ; the power of resisting the effects of credulity or
superstition can only be obtained from a knowledge of true scien-
tific principles.

In the first stage of the philosophy of nature, it was supposed

160 ROTAflON OF CROPS.

that the organic kingdom was developed from water alone ; then
it was considered that both water and air were necessary ; and
now we know, with the greatest certainty, that the soil furnishes
other important conditions, which must be added to the former,
otherwise plants will not obtain the power of propagating and
of multiplying themselves.

The quantity of food for plants in the atmosphere is limited,
but still it must be sufficient to cover the surface of the earth with
a rich vegetation.

In the tropics, and in those regions of the earth where a favor-
able soil, moisture, light, and an elevated temperature— the usual
conditions of fertility — are combined, the vegetation is scarcely
confined by the space on which it grows ; there, when the soil is
deficient, the bark and branches of dead plants soon form soil fdr
succeeding ones. It is obvious, therefore, that there is no
deficiency of atmospheric food for the plants of these regions,
and there can be none for our own cultivated plants.

The constant movement to which the atmosphere is subjected,
causes an equ^il distribution of the gaseous food necessary for
the growth of plants, so that the tropics do not contain more
of it than the cold zones ; and yet, how different appears
to be the power of production of equal surfaces of land in these
regions !

All plants of tropical regions, such as the sugar-cane, the
palms bearing wax and oil, contain, in comparison with our own
cultivated plants, only a small quantity of the constituents of
blood necessary for the nourishment of animals. The produce
in tubers, of an acre of potatoes, growing, as in Chili, to the
height of a tall bush, would scarcely suffice to prolong the life
of an Irish family for a day (Darwin). The nutritious plants
which are the objects of culture, are only a means for generating
the necessary constituents of tlie blood. If the ingredients of the
soil indispensable to their formation be absent from it, the consti-
tuents of the blood cannot be formed in the plants, although it is
possible that wood, sugar, or starch, might be produced under
such circumstances. If we desire to produce from a given sur-
face more of these constituents of the blood, than the plants
growing on it could receive from the atmosphere or from the soil

TROPICAL VEGETAtlON. 1«1

in their natural wild and normal condition, we must procure an
artificial atmosphere, and we must add to the soil the ingredients
in which it is deficient;

Very unequal quantities of* nourl.^hment must be furnished to
diflerent plants in a given time, in order to procure a free and
unimpeded growth. On arid sands, simple calcareous soils, or on
naked rocks, few plants flourish j and those that do are generally
perennial. These, growing slowly, require only small quanti-
ties of mineral ingredients, so that soils sterile for other kinds of
plants are still able to furnish to them mineral ingredients in
sufficient quantity. The apnuals, particularly summer plants,
reach complete maturity in comparatively a short time, so that
they do not flourish on a soil poor in the mineral substances ne-
cessary for their growth.

The food contained in the atmosphere does not suflice to
enable these plants to obtain their maximum of size in the short
period of their life. If the object of culture is to be attained,
there must be present in the soil itself an artificial atmosphere
of carbonic acid and ammonia, and this excess of nourishment,
which the leaves cannot get, must be conveyed to corresponding
organs existing in the soil.

But the ammonia with carbonic acid does not suffice to enable
itself to become a constituent of a plant fit for the food of animals.
Albumen cannot be formed without alkalies, and vegetable fibrin
and casein cannot be produced without the aid of phosphoric acid
and of earthy salts. We know tliat phosphoric acid is indis-
pensable for the production of the seeds of our cereals and culi-
nary vegetables, although the same ueid is found in large quan-
tity in an excrementitious form in ihe bark of woody plants.

How very different, in comparison with summer plants, are
the characters of evergreens, of mosses, ferns, and pines !
During every part of the day, both in summer and in winter,
they absorb by their leaves carbonic acid, which the sterile soils
cannot yield : their fleshy leather-like leaves retain with great
tenacity the water absorbed, and lose very little of it by evapora-
tion, in comparison with other plants. And yet how very small
is the quantity of mineral substances which they abstract from
the soil during the whole year of almost perpetual growth, when

162 ROTATION OF CROPS.

we compare it with the quantity removed from the soil in three
months by a crop of wheat of equal weight !

It follows, then, from the preceding observations, that the ad-
vantage of the alternate system of husbandry consists in the fact
that the cultivated plants abstract from the soil u'lequal quantities
of certain nutritious matters.

A fertile soil must contain in sufficient quantity, and in a form
adapted for assimilation, all the inorganic materials indispensable
for the growth of plants.

A field artificially prepared for culture, contains a certain
amouiit of these ingredients, and also of ammoniacal salts and de-
caying vegetable matter. The system of rotation adopted on such
a field is, that a potash-plant (turnips or potatoes) is succeeded by
a silica plant, and the latter is followed by a lime-plant. All these
plants require phosphates and alkalies — the potash-plant requiring
the largest quantity of the latter and the smallest quantity of the
former. The silica plants require, in addition to the soluble silica
left by the potash plants, a considerable amount of phosphates;
and the succeeding lime-plants (peas or clover) are capable of
exhausting the soil of this important ingredient to such an extent,
that there is only sufficient left to enable a crop of oats or of rye
to form their seeds.

The number of crops which may be obtained from the soil de-
pends upon the quantity of the phosphates, of the alkalies, or of
lime, and the salts of magnesia existing in it.

The existing provision may suffice for two successive crops
of a potash or of a lime-plant, or for three or four more crops of
a silica plant, or it may suffice for five or seven crops of all taken
together ; but after tiiis time, all the mineral substances removed
from the field in the form of fruit, herbs, or straw, must again be
returned to it ; the equilibrium must be restored, if we desire to
retain the field in its original state of fertility.

This is efiected by means of manure. It may be assumed that
the soil receives again, in the roots and stubble of the cereals, or
in the fallen leaves of Irees, as much carbon as its humus yielded
in the form of carbonic acid at the commencement of a new vege-
tation ; in like manner, the herb of the potatoe and the roots of the
clover renTiain in th<» soil. The remains of these plants enter into

RESTORATION OF THE INGREDIENTS OF THE SOIL. 103

decay during winter, and thus furnish to the young plant a new
source of carbonic ncid. The soil, therefore, is not exhausted of
its humus by the cultivation of these plants.

It may also be deduced from theoretical considerations, that the
soil receives during the life of the plants as much, or perhaps
even more, of carbonaceous materials as it yields to them ; and
that the soil is enriched in these matters by the process of secre-
tion proceeding at the surface of the fibres of the root ; the mat-
ters thus secreted enter into decay during winter, and pass into
humus.

Physiologists differ in their opinions with regard to the pro-
cesses of secretion and excretion by plants ; some affirm that these
processes do exist, while others deny their existence ; so that, at
this moment, the opinions are divided on the subject. But still,
no one denies that the oxygen separated by the leaves and green
parts of plants ought to be considered as an excrement. In the
act of vital activity, the plants assimilate the carbon of carbonic
acid, and the hydrogen of water, making them constituents of their
organs, while they separate part of the oxygen with which these
elements were combined.

In the blossoms we find volatile oils, compounds rich in carbon
and in hydrogen, and which are not further employed in any of
the vital processes : out of the bark we see flowing resin, balsam,
and gum ; and out of the leaves, sugar and mucilaginous sub-
stances.

Oxygen is not separated from the surface of the bark, roots, or
other parts that are not green ; but, on the contrary, these parts
separate substances rich in carbon which have been generated by
the vital processes of the plant, but have not experienced any
further change.

When we compare the barks of the fir,* pine, beech, or oak, •

* Ashes of Wood of Ashes of the Bt. '<

the Fir. of the Fir.

Hertw'g. Hkrtwig.

1000 wood gave '^•2S ashes. 1000 bark gave 1785 ashea

{Carbonate of soda - - 7-42
Carbonate of potash -1130 Soluble saita 2-95
Chloride of sodium ) r^
Sulphate of pot I h 5 ' ^""^^^

164

ROTATION OF CROPS.

with their sap and wood, we find that they differ essentially from
each other, both in their composition and characters.

True wood yields only one-fourth to two per cent, of ashes,
while the bark of the oak, fir, willow, and beech, gives 6, 10, to
15 times more. The ashes of wood and of the bark have a very
different composition. The inorganic ingredients of the bark
are obviously inorganic substances expelled by the living or-
ganism.

The same reasoning holds good in the case of the organic sub-
stances as it docs in the case of the bark. The bark of the cork-
tree contains nearly half its weight of fats, or of fatty substances,
which we also find present, although in smaller proportion, in the
bark of firs and pines. The solid material (insoluble in alcohol
or ether) of these barks is entirely different from woody fibre.
The barks of firs and pines are completely soluble in potash leys,
forming a liquid of a dark brown color, which yields, on the ad-
dition of an acid, a precipitate strongly resembling the substance
called humic acid. But wood is not attacked by potash ley.

These barks are in so far true excrements, that they arise from
living plants, and play no further part in their vital functions ;
they may even be removed from them, without thereby endanger-
ing their existence. It is known that certain trees throw off an-
nually their barks : this circumstance, viewed in its proper light,
shows that, during the formation of certain products formed by the
vital processes, materials arise which are incapable of experien-
cing a further change.

Ashes of Wood of

Ashes of the Bark

the Fir.

of the Fir.

Hkrtwiq.

Hertwio.

' Carbonate of lime - - 50 94 -

- 64-98'

Magnesia . - - . 5 00 -

- 0-93

Phosphate of lime - - 3-43 -

- 503

magnesia- 2-90 -

- 4 18

isoluble
Salts.

" manganese Traces -

-

Insoli ble

peroxide of > ^^ _
iron - 5 * "*

- 104

Salts 9 7-05

" alumina - 115 -

- 2 42

Silica - . - 13-37 -

- 17-2S

^Loss - - - - ;>-26 -

- 1-79

100-00

100 00

BARK VIEWED AS EXCRKMENTITIOUS Ifl/V

There is every reason to believe that this separation takes place
over the whole surface ; it is observed not only on the stem, but
also on the smallest twigs ; and hence we must conclude that the
same excretory process goes on in the roots.

When a branch of a willow is allowed to vegetate in rain-water,
the latter assumes gradually a dark-brown color. The same
phenomenon is observed in bulbous plants (such as hyacinths)
allowed to grow in pure water. It therefore cannot be denied
that excrements are actually separated by plants, although it is
very possible that they do not all separate them in the same
degree.

It is generally admitted by farmers, as the result of experience,
that a soil is enriched in organic matters by the culture tf peren-
nial plants, such as sainfoin and lucerne, which are distinguished
for the extensive ramification of their roots and strong gro^vth of
their leaves ; the cause of their enriching power will perhaps be
explained from the above remarks.

We cannot effect the formation of ammonia on our cultivated
land, but it is in our power to obtain an artificial production of
humils: this must be viewed as one of the objects of a system of
rotation, and as a second cause of the advantage arising from it.

By sowing a field with a fallow crop, such as clover, rye,
lupins, buck-wheat, &c., and by ploughing and incorporating with
the soil, the plants, when they have nearly come to blossom, we
procure to the young plants of a new crop sown on the field a
maximum of nourishment and an atmosphere of carbonic acid, in
consequence of the decay of the preceding crops. All the nitro-
gen drawn from the atmosphere by the preceding plants, and all
the alkalies and phosphates received from the soil, now serve to
cause a luxuriant growth to the plants which succeed.

166 ON MANURE.

CHAPTER XII.

On Manure.

In order to obtain clear ideas on the value and action of ani-
mal excrements, it is most important to bear in mind their origin.
It is wcU known, that when a man or an animal is deprived of food,
he becomes cnaciated, and his body diminishes in weight from
day to day. This emaciation becomes visible after a few days ;'
and in the case of persons who are starved to death, their fat and
muscular substance disappear, their body becomes empty of
blood, and at last nothing remains except skin and bones.

On the other hand, the weight of the body does not alter, even
though supplied with sufficient food ; for in the body of a healthy
man there is neither a marked increase nor diminution of weight
from one twenty-four hours to another.

These phenomena prove with certainty that a change proceeds
in the rganism of an animal during every moment of its life ;
and a part of the living substance of the body passes out from it
in a state more or less changed. The weight of the body, there-
fore, would decrease continually, if the parts separated or changed
were not again prepared and replaced.

The restoration and replacement of the original weight is
effected by means of food.

A man or an animal consumes daily a certain number of oun-
ces, or of pounds of bread, flesh, or other nutritive substances,
so that in a year he consumes an amount of food of a much
greater weight than that of his own body. He takes in the food
a certain quantity of carboi, hydrogen, oxygen, nitrogen, and
sulphur, as well as a very considerable quantity of mineral in-
gredients, which we have learned to know as the ashes of food.

What, it may be asked, has become of all these constituents
of the food, to what purposes have they been applied, and in

FOOD UNDERGOES COMBUSTION IN THE BODY. 1*7

what form have they been expelled from the body ? Carbon and
hydrogen have been furnished to the body, and yet the weight of
the body, with respect to these elements, has not increased : the
body has received in the food a quantity of alkalies and of phos-
phates, but still the amount of these substances in our body has
not been rendered greater.

These questions are easily solved, when it is considered that
the food does not supply the only conditions necessary for the
support of the viiui processes, for there are other conditions
which distinguish animals essentially from plants.

The life of an animal is essentially connected with a continual
introduction into its system of the oxygen contained in air.
Without ai/ and oxygen, animals cannot exist. In the process of
respiration, a certain quantity of oxygen is introduced into the
blood by means of the lungs. The air which we respire contains
this oxygen, and yields it to the constituents of the blood ; the
blood of an adult man removes from the air, at each respiration,
about two cubic inches of oxygen. A man consumes in 24 hours,
from 10 to 14 ounces of oxygen — in a year, hundreds of pounds ;
what then becomes of this oxygen ? We take into our bodies
pounds weight of food and pounds weight of oxygen, and never-
theless the weight of our body either does not increase to any
sensible extent, or it does so in a much smaller proportion than
corresponds to the food : in certain individuals (in old age) it
experiences a continued reduction.

It must be obvious, that this phenomenon is explicable only on
the supposition that the oxygen and the constituents of the food
exercise on each other in the organism a certain action, in con-
sequence of which both disappear from the body. This is actu-
ally the case ; for none of the oxygen respired as a gas into the
body remains in it ; it is separated in the form of carbonic acid
and water. The carbon and hydrogen, which have combined
with the oxygen, are derived from the organism ; but as these ele-
ments of the body are obtained from the food, it may be said,
that, in their final form, all the elements of food capable of uniting
with oxygen are converted, in the living body, to oxygenized
compounds, or, what expresses the same thing, they enter into
combustion.

ON MANURE.

When bread, flesh, potatoes, hay, or oats, are burned in a com-
mon fire-place, with an ordinary draught, but perfectly exposed to
the entrance of the air, the carbon of these substances is con-
verted into carbonic acid, their hydrogen into water, their nitro-
gen is set at liberty in the form of ammonia, and their sulphur
assumes the form of sulphuric acid, so that at last nothing re-
mains except the mineral ingredients of these substances in the
form of ashes. In the form of volatile products, we obtain car-
bonic acid, carbonate of ammonia, and water, and besides these
(if the combustion be incomplete), smoke or soot ; in the incom-
bustible residue we obtain all the salts contained in tiie tbod.

When water is poured over these ashes, the alkalies dissolve,
and also the soluble phosphates, common salt, and sulphates ;
the residue, insoluble in water, contains salts of' lime and magne-
sia, and silica, if the substance burned contained the latter sub-
stance.

Exa.'itly the same process ensues in the bodies of animals.
Through the skin, and by means of the lungs, the carbon and
hydrogen of the food are expelled in their final form of carbonic
acid and water ; all the nitrogen of the food is collected in the
urinary bladder in the form of urea, which by the simple union of
the elements of water is converted into carbonate of ammonia.

When the body regains its original weight, exactly as much
carbon, hydrogen, and nitrogen, as it took in the food, must have
been expelled from it. It is only in youth, and in the process of
fattening, that an increase in weight takes place, and that, there-
fore, part of the constituents of the food remains in the body : in
old age, on the contrary, the weight decreases, that is, more is
separated from the body than enters into it.

The nitrogen of the food is, therefore, daily expelled by the
urine in the form of urea and of compounds of ammonia. The
faeces contain the unburned substances of the food, such as the
woody fibre, chlorophyl,* and wax, which have suffered no
change in the organism ; the carbon, hydrogen, and nitrogen of
these substances are very small in quantity, in comparison with

* Chlorophyl is the green coloring matter of the leaves and other parta
ef plants.

ASHES OF FCK)D OBTALNED FROM SOILS. 169

.hat in the food. The mixture of these indigestible materials
with the secretions may be compared to the smoke and sooi
produced when food is imperfectl}' burned in a common fire-
1)1 ace.

It has been shown, by an examination of faeces and of urine, that
tlie mineral ingredients of the food, the alkalies, salts, and silica,
are eliminated in these excrements. Urine contains all the solu-
ble mineral substances of the food, while the faeces contain the
ingredients insoluble in water. As the food is burned in the
body just as it would be in a fire-place, the urine may be said to
contain the soluble salts of the ashes, and the fieces the insoluble
salts. — (Sec Appendix.) A horse

CONSUMKa Of INORKDIKNTS OF THK SOIL— AND THE EXCRKMKNTS RETURN —

Ounces of Ashet*. Ounces of Ashes.

In I51bs. hay* .
In 4-5-t oats

In its drink .

1801) In urine . 3-51 > .-,,.0-,

2-40 S 21-40 In faeces . 18.36 5"'^'
0-42 >

A. COW—

(;-67)

In urine .

12-29

20-20 > 28-47

In faeces .

, 16-36

JO S

In milk

1-SO

In 30 lbs. of potatoeM .

In hay . ... -20-20^28-47 In faeces . 16-36^30-45

In its drink .

These analyses show, as nearly as can be expected from ex-
periments of this kind, that all the con^ituents of the ashes of
the food are again obtained, without alteration, in the solid and
liquid excrements of the horse and cow. The action produced
upon our fields, by the liquid and solid excrements of animals,
ceases to be mysterious or enigmatical, as soon as we have at-
tained a knowledge of their mode of origin.

The mineral ingredients of food liave been obtained from our
fields, having been removed from them in the form of seeds,
of roots, and of herbs. In the vital processes of animals, the
combustible elements of the food are converted into compounds
of oxygen, while the urine and tiie faeces contain the constituents of
the soil abstracted from our fields ; so that, by incorporating
these excrements with our land, we restore it to its original state
of fertility. If they are given to a field deficient in ingredients
necessary for the growtli of plants, it will be rendered fertile for
all kinds of crops.

• Bonssin^nult, Annales de Chimie et de Physique, Xxxi
0

1% ON MANURE.

A part of the crop taken from a fielJ is used in feeding and
fattening animals, which are afterwards consumed by man.
Another part is used directly in the form of potatoes, meal, or
vegetables ; while a third part, consisting of the remnants of
plants, are employed as litter in the form of straw, &c. It is evi-
dent that all the constituents of the field removed from it in the
form of animals, corn, and fruit, may again be obtained in the
liquid and solid excrements of man, and in the bones and blood
of the slaughtered animals. It altogether depends upon us to keep
our fields in a constant state of composition and fertility by the
careful collection of these substances. We are able to calculate
how much of the ingredients of the soil are removed by a sheep,
by an ox, or in the milk of a cow,* or how much we convey
from it in a bushel of barley, wheat, or potatoes. From thje
known composition of the excrements of man, we are also able to
calculate how much of them it is necessary to supply to a field
to compensate for the loss that it has sustained.

It is certainly the case, that we could dispense with the excre-
ments of man and animals, if we were able to obtain from other
sources the ingredients on which depends all their value for agri-
culture. It is a mafter of no consequence whether we obtain
ammonia in the form of urine, or in that of a salt from tlie pro-
ducts of the distillation of coal ; or whether we obtain phos-
phate of lime in the form of bones, or as the mineral apatite. The
principal object of agriculture is to restore to our land the sub-
stances removed from it, and which the atmosphere cannot yield;
in whatever way the restoration can be most conveniently effected.

• 1000 parts of milk yielded, by incineration —

1 67-7 Residue.

II 490

100 parts of the ashes of the milk consisted of : —

Phosphate of lime .
" magnesia

Perphosphate of iroa
Chloride of potassium
Co iimoa salt
Sotla

I.

II.

. . 47-14

50-81

. . 8.57

9.45

. . 1.43

1-04

. . a9-39

27-03

. . 4-89

5"

. . s r)7

() (', I

99-9S

i;>«v)!)j

phosphate; or food restored by excrements, r.i

If the restoration be imperfect, the fertility of our fields, or of
the whole country, will be impaired ; but if, on the contrary, we
add more than we take away, the fertility will be increased.

The importation of urine or of solid excrements from a foreign
land, is quite equivalent to the importation of corn and cattle.
All these matters, in a certain time, assume the form of corn,
flesh, and bones ; they pass into the bodies of men, and again as-
sume the same form which they originally possessed. The only
true loss that we experience, and that we cannot prevent, on ac-
count of the habits of our times, is the loss of tlie phosphates,
which man carries in his bones to the grave. The enormous
quantity of food, which man consumes during the sixty years of
his life, and every constituent of it that was derived from our
fields, may again be obtained and restored to tiiem. It is quite
certain, that it is only in the bodies of our youth, and in those of
growing animals, that a certain quantity of phosphate of lime is
retained in the bones, and of alkaline phosphates in the blood.
With the exception of this extremely small proportion, in coni-
parison with the actual quantity existing in the food, all the salts
with alkaline bases, and all the phosphates of lime and magne-
sia, which animals daily consume in their food, — in fact, there-
fore, all the inoro;anic ingredients of the food, — are again obtained
in the solid and liquid excrements. Without even instituting an
analysis of these excrements, we can with ease indicate their
quantity and their nature, and we can estimate their composition.
We furnish to a horse daily 4^ lbs. of oats and 15 lbs. of hay ;
the oats yield 4 per cent., the hay 9 per cent, of ashes ; aiid from
these data we calculate, that the daily excrements of the horse
must contain 21 ounces of inorganic materials, which have been
obtained from our fields. The analyses of the ashes of hay and
of oats inform us in per centage how much silica, alkalie* •^d
phosphates are contained in them.*

• The ashes of oats contain, according to Saussure —

In 100 parts.
Soluble salts with alkaline bases - - 16
Phosphate of lime ^ - - - - - 24
Silica 60

The Mhes of hay contain, according? to Hajdlkjt —

ITS ON MANURE.

The nature of the fixed ingredients in the excrements varies
according to the food. If we feed a cow on mangel-wurzel, or
potatOGvS, without hay or barley straw, its solid excrements will
not contain silica, but they will contain phosphates of lime and
magnesia, and the liquid excrements will contain carbonates of
potash and soda, and also compounds of these bases with inorganic
acids. If the fodder or food yield, on incineration, ashes contain-
ing soluble alkaline phosphates (such as bread, meal, all kinds
of seeds and flesh), we obtain from the animal fed upon these,
urine in which the alkaline phosphates exist. But if the ashes
of the food (such as hay, turnips, and potatoes), do not contain
any soluble phosphate of the alkalies, but only insoluble earthy
phosphates, then, the urine is free from the alkaline phosphates,
and the faeces are found to contain the earthy phosphates. The
urine of men and of animals subsisting upon flesh and grain con-
tains alkaline phosphates ; while that of animals living wholly
upon grass is destitute of these salts. The analyses of human
excrements,* those of birds living upon fish (guano), and of

In lUO parts.
Phosphate of lime - - - - 16 1

Perphosphate of lime - - - . 5'0

Liioe 2-7

Magnesia ------ 8"6

Sulphate of soda - - - - - 1*2

•• potash - - - - 22

Chloride of potassium - - - - 1*3

Carbonate of soda - - - - Vl

•* potash - - - - 0'9

Silica - - - - - - - 60'6

Loss 0-8

• According to tlie analysis of Berzelius, 1000 parts of human urine
contain —

1000 p»rt« of 1000 parts of
Urioe. the residue.

Urea 3010 44-39

Free lactic acid, lactate of ammonia, and^

animal matters not separable from >i 71 4 25.J>S

them - « - - - - S

Uric acid - - . - - -100 1-49

Mucus of the bladder . . » . 0*32 0*48

Sulphate of potash .... 3*71 5*54

" soda 316 4-72

EXCREMENTS RESTORE ASHES OF PLANTS. 173

the excrements of the horse and of the cow (see Appendix),
yield conclusive proof of the nature of the salts contained in
them.

In the solid and liquid excrements of man and of animals, we

RESTORE TO OUR FIELDS THE ASHES OF THE PLANTS which SerVcd

to nourish these animals. These ashes consist of certain soluble
salts and insoluble earths, which a fertile soil must yield, for they
are indispensable to the growth of cultivated plants.

It cannot admit of a doubt, that, by introducing these excre-
ments to the soil, we give to it the power of affording food to a
new crop, or, in other words, we reinstate the equilibrium which
had been disturbed. Now that we know that the constituents of
the food pass over into the urine and excrements of the animal
fe(} upon it, we can with great ease determine the different value
of various kinds of manure. The solid a.nd liquid excrements

OF AN animal are OF THE HIGHEST VALUP. AS MANURE FOR THOSE
PLANTS WHICH FURNISHED FOOD TO THE ANIMAL. The duDg of

pigs fed upon peas and potatoes, is in the highest degree adapted
as a manure for fields growing peas and potatoes. We feed a

1000 parts of
Urine.

|0(K) parts of
the residue

Phosphate of swla . - -
" ammonia - - -

- 2-94

- ] -65

4-39
2-46

Chloride of sodiui^i - - -

- 4-45

6-64

Muriate of ammonia - , .

- 1-50

2-23

Phosphates of magnesia and Hme -
Silica - -, -

- 1-00

- 0-03

1-49
005

Water

- 933-00

10000

1000-00

1000 parts of hunaTi faeces yielded 150 f •

irti. of asiies,

which consisted

of— (Berzelius) : —

Phosphate of lirrie

■ - ?

" magnesia
Traces of gypsum
Sulphate of siwli

'* j)otash
Phosphate of soda
Carbonate of soda
Silica ....
Carbonaceous lesid'.ie and loss

: : \

100

8

8
16

18

150

174 ON MANURE.

cow upon hay and turnips, and we obtain a manure containing
all the mineral constituents of grass and of turnips ; this manure
ought to be preferred, as being more suitable for turnips than
that procured from any other source. The dung of pigeons con-
tains the mineral ingredient of the cereal grains ; that of the
rabbit, the constituents of culinary vegetables ; the liquid and
solid excrements of man contain in very great quantity the
mineral substances of all seeds.

According to the above view, a knowledge of the constituents
of the ashes of food and of fodder, gives us an exact indication
of the ingredients of the soil contained in the liquid and solid ex-
crements of men and of animals.

If we know the quantity of the food, and the composition of its
ashes, we know also with certainty how much soluble salts will
be contained in the urine, and how much of the insoluble salts
will exist in the ffeces. It would, therefore, be superfluous and
useless to state Jiere a greater number of analyses of excrements,
because these analyses must differ from each other, quite as
much as tlic variation in composition of the ashes of the food on
which the animal was fed.

Common stable manure is a mixture of j^olid excrements with
urine, which gradually enters into putrefaction in the dunghill.
In consequence of the putrefliclion of the urine, all the urea con-
tained in it is converted into volatile cy.rbonate of ammonia. A
large portion of the organic ingredients of the manure enter into
decay and assume a gaseous condition, by the action of the air,
with the continued evolution of heat. The weight of these
ingredients diminishes, while the relative proportion of the fixed
mineral substances increases. if all the d«:;caying matters
entered into union with oxygen, the result of course would be,
that those not susceptible of decay, or, in otlier words, the ashes,
would alone reniain behind. Ti)e following analysis will illus.
irate the meaning of tiiis remark : —

100 })art.s fresh Cow-dung —

Water . . 1 . . . S5-900

Combustible substances - 12*

Ashes •— ''-'''

2-352 >
1-74S5

100000

MANURE LOSES ORGANIC MATTER BY AGE.

100 parts Stable Manure; i year old.*
Welter - - - - - - - 79-3

Coi'ibas*ible substances - 14'04 )
Ashes 6 66 5

20-7
100.0

Now that we k'''Ort t'lnt the proportion of the mineral food of
plants increases with tlie age of the dung, that old dung may
contain 4 to 6 times more of it than fresh dung, an explanation is
furnished of the relatively greater action of the former, and of
the preference accorded to it by farmers of experience.

It has been mentioned in the preceding part of the chapter,
that animal excrements may be replaced in agriculture, by other
materials containing their constituents. Now, as the principal
action of the former depends upon their amount of mineral food
so necessary for the growth of cultivated plants, it follows, that
we might manure with the mineral food of wild plants, or in
other words, with their ashes ; for these plants are governed
by the same laws, in their nutrition and growth, as cultivated
plants themselves. Thus, these ashes might be substituted for
animal excrements ; and if a proper selection were made of them,
we might again furnish our fields with all the constituent.**
removed from them by crops of cultivated plants. The vast im-
portance of ashes as a manure is recognised by many farmers.
In the vicinity of Marburg, and in the Wetterau, such a high
value is attached to this costly naterial, as a manure, that the
farmers do not object to send foi t to a distance of 18 or 24 miles.
The importance of this manure will be more obvious, when it is
considered, that wood-ashes lixiviated with cold water contain
silicate of potash, in exactly the same proportion as straw
(10 Si O3, + KO) ; and that, in addition to this salt, it contains
considerable quantities of phosp'iytcs.

Different kinds of wood-ashes ])ossess very unequal value as
manure. Thus, the r.si.e.-s of the oak are of the smallest, those
of the beech of t'jc j^-reatest vi-ue. Wood-ashes from oak contain
4 to 5 per cent, of phcsphatfs ; those from the beech contain the
fifth part of their weight of these salts. The quantity of phos.

• Annales f]e Chirnio et de Physique, iii. Serie, 237.

176 ON MANURE.

phates in the ashes of firs and pines amounts to from 9 to 15 per
cent. : the ashes of the poplar contain 16 J per cent., and those
of the hazel-nut tree 12 per cent.*

With every hundred pounds of lixiviated ashes of the beech,
we furnish to the soil as much phosphates as are contained in
460 lbs. of fresh human excrements.

According to the analysis of Saussure, 100 parts of the ashes
of grains of wheat contain 32 parts soluble and 44-5 parts inso-
luble, or altogether 76*5 parts of soluble and insoluble phosphates.
The ashes of wheat-straw contain in all 11*5 per cent, of phos-
phates. Thus with every 100 lbs. of the ashes of beech, we
furnish to the field phosphoric acid sufficient for the production
of 4000 lbs. of straw (calculating its ashes at 4 per cent., accord-
ing to Saussure), or for 2000 lbs. of the grains of wheat (calcu-f
lating their ashes at 1-3 per cent. — Saussure).

The dry fruit of the horse-chestnut {JEsculus hippocastanum)
yields 34 per cent, of ashes, possessing a similar composition to
the ashes of maize, and of the grain of certain kinds of wheat. f

The importance of manuring with bones must be obvious to
all. The bones of man, and of animals in general, have their
origin from apatite (phosphate of limo), which is never absent
from fertile land. The bone earth passes from the soil into hay,
straw, and other kinds of food, which are afterwards consumed
by animals. Now, when we consider that bones contain 55 per
cent, of the phosphates of lime and magnesia (Berzelius), and if
we assume that hay contains the same quantity of these salts as

• Ashes of pines from Norway contain the jiiininmm of phosphates —
viz. 0*9 per cent. — Berthier.

t Ashes of the fruit of the horse-chestnut [Saussurk]:

Potash 51

Alkaline phosphate? - . - - 28

Chloride of potasni'^rr. x:A sulphate ^^ ^ o

potash - - - - 5

Earthy phosphates .... 12

Silica 05

Metallic oxides - - - - -025

Loss ..... , 5.25

10000

BONE MANURE. 17T

wheat-straw, then it follows that 8 lbs. of bones contain as much
phosphate of lime as 1000 lbs. of hay or of wheat-straw, and 20
lbs. as much phosphoric acid as 1000 lbs. of the grain of wheat
or of oats. These numbers are not absolutely correct, but they
give a very fair approximation of the quantity of phosphates
yielded annually by a soil to these plants. By manuring an acre
of land with 60 lbs. of fresh bones, we furnish sufficient manure
to supply three crops (mangel-wurzel, wheat, and rye) 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 assimi-
lated. The most easy and practical method of effecting their
division is to pour over the bones, in a state of fine powder, half
their weight of sulphuric acid diluted with three or four parts of
water, and after they have been digested for some time, to add
about one hundred parts of water, and to sprinkle this acid mix-
ture (phosphates of lime and magnesia) 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 state of very fine division.
Experiments instituted on a soil formed from grauwacke, for the
purpose of ascertaining the action of the manure thus prepared,
have distinctly shown that neither corn nor kitchen-garden plants
suffer injurious effects in consequence ; but that, on the contrary,
they thrive with much more vigor.*

In the manufactories of glue, many hundred tons of a solution
of phosphates in muriatic acid are yearly thrown away as be
ing useless. It would be important to ascertain how far this
solution might be substituted for bones. The free acid would

* Very favorable results have been obtained by treating seeds in the fol
lowing manner: — The seeds about to be sown were steeped in the water
from a dunghill, and while still wet, were strewed with a mixture of 20
parts of fine bone-dust and 1 part of burnt gypsum, in such a manner that
each grain was covered with a thin layer of the powder ; by sprinkling
them with water and repeating this treatment with the mixture, the coat-
ing can be increased. The seeds were allowed to dry in the air, and were
then sown in the usual way. On the brge scale this mode of dunging
owing to its being rather troublesome, might not answer the purj)ose M
well as a heavy manuring with bones and gvpsum.
9-^

17S ON MANURE

combine with the alkalies in the soil, especially with lime, and a
soluble salt would thus be produced, which is known to possess a
favorable action on the growth of plants. This salt (muriate of
lime, or chloride of calcium) is one of those compounds which
attract water from the atmosphere with great avidity, and retain
it when absorbed ; and being present in the soil, it would decom-
pose the carbonate of ammonia existing in rain-water, with the
formation of sal-ammoniac and carbonate of lime. A solution
of bones in muriatic acid placed on land in autumn or in winter,
would therefore not only restore a necessary constituent of the
soil, but would also give to it the power of retaining all the am-
monia falling upon it in the rain for a period of six months.

The ashes of brown coal and of peat contain frequently silicate
of potash, so that these might furnish to the straw of the cereals
one of its principal constituents; these ashes contain also'
phosphates.

ft 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 favorable action on vegetation ; and it is likewise cer-
tain, that the cause of this is their containing a body, which, inde-
pendently of the influence exerted by its physical properties of
porosity and capability of attracting and retaining moisture, as-
sists also in maintaining the vital processes of plants. But if the
subject be treated as an unfathomable mystery, the nature of
their influence will never be known.

In medicine, for many centuries, the mode of action of all reme-
dies was supposed to be concealed by the mystic veil of Isis ;
but now these secrets have been explained in a very simple man-
ner. An unpoetical hand has pointed out the cause of the won-
derful and apparently inexplicable healing virtues of the springs
in Savoy, by which the inhabitants cured their goitre : the water
was found to contain small quantities of iodine. In burnt sponges
used for the same purpose, the same clement was also detected.
The extraordinary efficacy of Peruvian bark was found to depend
on a small quantity of a crj'stalline body existing in it, viz.
<^uinine ; and the causes of the various effects of opium were
detected in as many different ingredients of that drug.

CAUSES OF ACTION SHOULD BE ASCERTAINED. tW

Now all such actions depend on a definite cause, by ascertain'
ing 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 com-
pletely restored to it ; but whether this restoration be effected bv
means of excrements, ashes, or bones, is in a great measure d
matter of indifference. A time will come, when plants growing
upon a field will be supplied with their appropriate manures pre
pared in chemical manufactories — when a plant will rec(;ive only
sucl) substances as actually serve it for food, just as at presen* a
few grains of quinine are given to a patient afflicted with fever,
instead of the ounce of wood which he was formerly compelled
to swallow in addition.

There are some plants which require humus (as a source of
carbonic acid), without re-producing it in any appreciable quantity ;
whilst others can do without it altogether, and actually enrich a
soil deficient in it. 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; but would in fact make
use of them for supplying the others with humus.

We may furnish a plant with carbonic acid, and with 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, on the other hand, the supply of nitrogen, in the form of
ammonia, will not suflice for the purposes of agriculture. Al
though ammonia is of the utmost importance for the vigorous
growth of plants, it is not in itseif sufficient for the production of
vegetable casein, fibrin, or albumen. These substances are not
known in a free state ; for they are always accompanied by alka*
lies, sulphates, and phosphates. We must therefore assume, that
without their co-operation, ammonia could not exercise the slight-
est influence on the growth and formation of the seeds ; that, ih
such a case, it is a matter of perfect imlifference whether ani-
monia is conveyed to them or not ; for it will not assist in the
formation of the constituents of the blood, unless tlie other oondif^

ISO JN MANURE

tions necessary for their production be present at the same
time.

All these conditi.i:s are united in liquid and solid excrements;
none of them are absent. In these are present, not only ammo-
nia, but also alicalios, phosphates, and sulphates, in the relative
pre ition in which they exist in our cultivated plants.

The pDwerful action -f urine depends, therefore, not only on
Its compounds of nitr "^gen ; for the phosphates and sulphates ac-
companying these take a ^ecidod part in the action.

Urine, in the state in which it is used as manure, does not con-
tain urea, as this substance has been converted into carbonate of
ammonia during putrefaction. In dung reservoirs, well con-
structed and protected from evaporation, the carbonate of ammo-
nia Is retained in solution. When the putrefied urine is spread
over the land, part of its carbonate of ammonia evaporates along
with the water, while another portion is absorbed by the soil, par-
ticularly if it be clayey and ferruginous land; but, in general,
only the phosphate and muriate of ammonia remain in the ground.
The amount of the latter alone enabJes the soil to exercise a
direct influence on the plants during the progress of their growth ;
and as they are not volatile, not a particle of them escapes being
absorbed by the roots.

The existence of carbonate of ammonia in putrefied urine long
since suggested the manufacture of sal-ammoniac from this ma-
terial. When the latter salt possessed a high price, this manu-
facture was carried on by the farmer himself. For this purpose
the liquid obtained from dunghills was placed in vessels of iron
and subjected to distillation ; the product of this distillation was
then converted into muriate of ammonia by the ordinary methods
(Demachy).

The carbonate of ammonia formed . y the putrefaction of urine
can be fixcv^, or be deprived of its volatility, in many ways.
When a field is strewed with gypsum, and then with putrefied
urine, or with the drainings of dunghills, all the carbonate of
ammonia is converted into the sulphate, which remains in the
soil.

But there are still simpler means of effecting this purpose :
gypsum, chloride of calcium, sulphuric or muriatic acid, and

CARBONATE OF AMMOxViA IN L.?*NF. 181

superphosphate of lime, are substances of a very low price ; and
if they were added to urine until the latter lost its alkalinity, the
ammonia would be converted into salts, which would have r.o
further tendency to volatilize.

When a basin, filled with concentrated muriatic acid, is placed
in a common necessary, so that its surface is in free communica-
tion with the vapors issuing 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 escaping in this
manner is not only 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 dissolves gradually
the lime. The injury thus done to a building by the formaticr
of soluble nitrates, has received (in Germany) a special name •
salpeterfrass (production of soluble nitrate of lime).

The ammonia emitted from stables and necessaries is always
in combination with carbonic acid. Carbonate of ammonia and
sulphate of lime (gypsum) cannot be brought together at common
temperatures, without mutual decomposition. The ammcnia
enters into combination with the sulphuric acid, and the carbonic
acid with the lime, forming compounds destitute of volatility, and
consequently of smell. Now, if we strew the floors of our stables,
from time to time, with common gypsum, they will lose all their
ofFensive smell, and none of the ammonia can be lost, but will be
retained in q, condition serviceable as manure (Mohr).

With the exception of urea, uric acid contains more nitrogen
than any other substance generated by the living organism ; it is
soluble in water, and can be thus absorbed by the roots of plants,
and its nitrogen will be assimilated in the form of ammonia from
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. previously
heated to redness, and then mixed with pure uric acid. The ex-

ON MANURE.

aminatioii cf the juice of the plant, or of the component parts of
the seed or fruit, would be an easy means of detecting the
differences.

In respect to the quantity of nitrogen contained in excrements,
iOO parts of the urine of a healthy man are equal to 1300 parts
«4)f the fresh dung of a horse, according to the analysis of Macaire
and Marcet, and to 600 parts of the fresh dung of a cow.
The powerful effects of urine as a manure are well known in
Flanders, and they are considered invaluable by the Chinese, who
are the oldest agricultural people we know. Indeed, so much
alue IS attached to the influence of human excrements by these
'oeople, that laws of the state forbid that any of these excrements
should be thrown away, and reservoirs are placed in every house,
m which they are collected with the greatest care. No other
kind cf manure is used for their corn-fields.

On the assumption, that the liquid and solid excrements of man
amount, on an average, to only 1^ lb. daily (^ lb. of urine and
J lb. faeces), and that both taken together contain 3 per cent, of
nitrogen, then, in one year, they will amount to 547 lbs., con-
taining 16*41 lbs. of nitrogen, a quantity sufficient to yield the
nitrogen of 800 lbs. of wheat, rye, oats, or of 900 lbs. of barley.

(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 ab-
sorbed from the atmosphere, the richest crops every year. By
adopting a system of rotation of crops, every town and farm might
thus supply itself with the manure, which, besides containing
the most nitrogen, contains also the most phosphates. By using,
at the same time, bones and the lixiviated ashes of wood, animal
excrements might be completely dispensed with on many kinds
of soil.

When human excrements are treated in a proper manner, so as
to remove this moisture, without permitting the escape of am-
monia, 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 nigiit-soil for transportation constitutes not an unimportant
branch of industry.

NITROGEN IN EXCREMENTS, 183

In Paris, for example, the excrements arc preserved in tho
houses in open casks, from which they are collected and placed
in deep pits at Montfauqon, but they 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, all their urea is converted for the most part into carbonate
of ammonia : the vegetable matter contained in them putrefies,
all the sulphates are decomposed, and the sulphur forms sul-
phuretted hydrogen (volatile hydrosulphate of ammonia). The
mass, when dried by exposure to the air, has lost the greatest part
of its nitrogen along with its water, and llie residue, besides phos-
phate of annnonia, consists for the most p.irt of phosphate of lime
and magnesia, together with fatty matters. Tins manure is sold
in France under the name of FoudreltSf and is very highly esti-
mated, on account of its powerful action. TJiis action cannot
depend on the ammovj'r. originally contained in it, because the
greatest part has escaped daring the desiccation. According to
the analyses of Jaquemars, the I'arisian poutlrolle does not con-
tain more than 1'8 per cent, of annnonia.

In other manufactories of manure, the night-soil, whiht still
soft, is mixed with the ashes of woo;l, or with earth, <&c., con-
taining a large quantity of c?.ustic linje, and this causes a com-
plete expulsion of all the ammonia of the excrements, depriving
them in consequence of all smell. The efficacy of this' manure
cannot, therefore, depend upon its nitrogen.

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 ihe soil nnist increase
every year; for to the quantity which we thus supply, another
portion is added from tho atmosphere. There is no proper loss
of nitrogen to plants, for even the small quantity of this elei.ient
which man carries with him to the grave is not finally lost to
vegetation, for it escapes into the earth, and into the atmosphere,
as ammonia, during the decay and putrefaction of the body.

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

I8i ON MANURE.

The substances applicable as manure ought to be arranged
according to the products desired. Tile alkalies are peculiarly
necessary for the production of vegetable constituents destitute
of nitrogen, such as sugar, starch, pectin, and gum ; phosphates
are peculiarly valuable for the formation of the constituents of
the blood. A field richlv treated with animal manure, and
therefore with phosphates, producea a barley which is rejected
by the brewer of beer, because it is too rich in the constituents
of the blood, and proportionally poor in starch. Hence, the
very ingredient which is of the highest value to the feeders of
stock, is held in low estimation by the brewer ; because the
object of the first is to produce flesh, the object of the latter is
the fabrication of alcohol.

Frefsli bones, wool, hair, rags, hoofs, and horn, are manures
containing nitrogen as well as pliosphates, and are consequently
fit to aid the process of vegetable life.

One hundred parts of dry bones contain from 32 to 33 per
cent, of dry gelatine ; now, supposing this to contain the same
quantity of nitrogen as aniraal 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 for thousands of years, in dry, or
even in moist soils, provided the access of air 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 is decomposed, and its nitrogen
is converted into carbonate of ammonia and other ammoniacal
salts, which are retained in a great measure by the powder
itself.*

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.

Ingenhouss proposed dilute sulphuric acid as a means of in-

* Boneit burnt till quite white, and recently heated to redness, absorb
7*5 times their volume of pure ammoniacal gas.

BONE MANURE. IM

creasing the fertility of a soil. Now, when this acid is sprinkled
on calcareous soils, gypsum (sulphate of lime) is immediately
formed, which, of course, prevents the necessity of manuring the
ground with this material. 100 parts of concentrated sulphuric
acid diluted with from 800 to 1000 parts of water, are equiva-
lent to 176 parts of gypsum.

Many kinds of ashes, of peat, and most varieties of coal
ashes, contain an abundant quantity of gypsum, by which they
exercise a very favorable influence on certain soils.

Ashes f>f iMjfit

Ashes of peat

from Fichtelgebirge.

from Bassy (Dep. de la Mnni*>

FlKKKTSCHKR

Bkrthikr.

Silica - - - 36 0^

Alumina - - 17-3 > -

- 22-5

Peroxide of iron - 330 )

Carbonate of lime - 20 ) _
Magnesia - - 35 ) ' * '

- .^1-5

Gypsum - - - 4'5 - -

- 360

Chloride of calcium 0-5

Carbonaceous residue 2'7

t8« RETROSPECT.

CHAPTER XIII.

Retrospective View of the Preceding Theories.

The knowledge of the processes of nutrition, in the case of the
culture of meadow and of forest land, indicates that the atmo-
sphere contains an inexhaustible quantity of carbonic acid.

On equal surfaces of wood or of meadow land, in which exist
the constituents of the soil indispensable to vegetation, we obtain
crops without the application of carbonaceous manures ; ancl
these crops contain, in the form of wood and hay, a quantity of
carbon equal to, or, in many cases, greater than that produced
by cultivated land in the form of straw, corn, and roots.

It is obvious that the cultivated land must have presented to it
as much carbonic acid as is furnished to an equal surface of
wood or of meadow land ; that the carbon of this carbonic acid
becomes assimilated, or is capable of assimilation, if the con-
ditions exist for its reception and conrersion into a constituent
of plants.

However great may be the supply of food in a soil, it will be
sterile for most plants, if water be deficient. At certain seasons
of the year rain fructifies our fields; seeds neither germinate
nor grow without a certain quantity of moisture.

The action of rain is much more striking and wonderful to the
superficial observer than that of manure. For weeks and
months, the influence wiiich it exerts on the crops is appreciable,
and yet very small quantities of carbonic acid and ammonia are
introduced to the soil by means of rain.

Water plays, doubtless, a decided part in the growth of plants,
by virtue of its elements ; but, at the same time, it is a mediating
member of all organic life. Plants receive from the soil, by the
aid of water, the alkalies, alkaline earths and phosphates neces-
sary to the formation of thsir organs. If these substances,

CARBONIC ACID FURNISHED BY HUMUS. 187

which are necessary for the passage of atmospheric food into the
organism of the plant, be deficient, its growth must be impeded.
Its proper growth, in dry seasons, stands in exact relation to the
quantity of the substances taken up from the soil during the first
period of its development. But on a soil poor in mineral food,
cultivated plants do not flourish, however abundantly water may
be supplied to them.

The crop of a meadow, or of an equal surface of wood-land, is
quite independent of carbonaceous manures, as far as regards
its carbon ; it is dependent on the presence of certain ingredients
of the soil destitute of carbon, and also on the conditions which
enable these to enter into the plants. Now, we are able to in-
crease the crop of carbon on our cultivated lujid, by the use of
burnt lime, ashes, or marl, — by substances, therefore, which are
entirely free from carbon. This well-ascertained tact indicates
that we furnish to tiie field, in these substances, certain constitu-
ents, which enable the cultivated plants to increase in mass, and
consequently in carbon — a power which they possessed formerly
only in a small degree.

After these considerations, it cannot be denied that the sterility
of a field, or its poverty of produce in carbon, does not arise
from a deficiency of carbonic acid, or of humus ; for we have
seen that this produce can be increased, to a certain extent, by
the supply of matters destitute of carbon. Rut the" very same
source which supplies the meadow and woodland wilh carbon,
namely the atmosphere, can yield that element to cultivated
plants. It therefore becomes especially necessary in agriculture
to employ the best, and most convenient means, of enabling the
carbon of the atmosphere (carbonic acid) to pass over into the
plants growing on our fields. The art of agriculture, in the
mineral food which it supplies, furnishes to plants the means of
appropriating their carbon from sources offering an inexhaustible
provision. But when these constituents of the soil are wanting,
the most abundant supply of carbonic acid, or of decaying vege-
table matter, cannot increase the crop>s on the field.

The quantity of carbonic acid that can pass from the air inio
plants, is limited, in a given time, by the quantity of carbonic
acM entering into contfict with the org;uis destined for its absorp-

188 RETROSPECT

tion. Now, the passage of carbonic acid from the air into the
organisMi of the plant is efTected by means of the leaves ; hut
the absorption of carbonic acid cannot take place without the
contact of its particles with the surface of the leaf, or of a part
of the plant capable of absorbing it. Hence, in a given timi
the quantity of carbonic acid absorbed must stand in exact pro-
portion to the surface of the leaves, and to the amount of it exist-
ing in the air.

Two plants of the same kind, with equal surfaces of leaves
(i. e. surfaces of absorption), will take, during the same time, and
under like conditions, t)ie same amount of carbon. And if the
air contains double the quantity of carbonic .icid tha* it does at
another time, the plants, under like conditions, will absorb double
the quantity of carbon.* A plant with only half the surfaces
of the leaves of another plant will absorb quite as much carl)on
as the latter, if the air supplied to the former contains twice the
amount of carbonic acid.

These considerations point out to us the cause of the favorable
action exerted on cultivated plants by humus, and by all decaying
organic substances.

Young plants, when dependent on the air alone, can cnlv
increase their amount of carbon according to their absorbing
surfaces. But it is obvious, if their roots receive, by means of
Immus, three times the amount ot carbonic acid absorbed by
their leaves in the same time, their increase in weight will bo
fourfold, on the assumption of the existence of all the conditions
for the assimilation of the carbon. Hence, four times the quan-
tity of stems, leaves, and buds, must be formed ; and, by the
increased surface thus obtained, the plants will receive in the
same degree an increased power of absorbing food from the air ;
and this power remains in activity long after the supply of carbon
to the roots has ceased.

But the use of hunms as a source of carbonic acid, in arable
land, is not only to increase the amount of carbon in the plant ;

• Boussingault remarked that leaves of a vine inclosed in a globe re-
moved completely from the air all the carbonic acid contained in it, how-
ever rapidly the stream of air was made to pass. (Dumas: Lecturei*
p. 23.)

UNEQUAL PRODUCTION OF CONSTITUENTS. 18«

for, by the increased size attained by the plant in a given time,
there is also given, in fact, space for the reception of the consti-
tuents of the soil necessary for the formation of new leaves and
twigs.

From the surface of young plants a constant evaporation of
water takes place, the amount of which is in proportion to the
temperature and surface. The numerous fibres of the roots
supply the water which is evaporated, just as if they were so
many pumps ; so that, as long as the soil continues moist, the
plants receive, by means of water, the necessary constituents of
the soil. A plant with double the surface of another plant must
evaporate twice the (juantity of water that the latter does. The
water thus absorbed is expelled again in vapor, but the salts and
constituents of the soil introduced to th(i plant by its agency,
.still remain there. A plant with twice the surface of leaves of
another plant, but with the same quantity of water in proportion
to its size, still receives from the same soil a greater quantity
of ingredients, in proportion to its water, than the latter plant
receives.

The growth of the latter soon reaches a termination when the
further supply ceases, while the former continues to grow, be-
cause it contains a larger quaiitity of the substances necessary
for the assimilation of atmospheric food. But m both plants the
number and size of the seeds will altogether depend upon the
amount of the mineral ingredients of the seed existing in the
plants ; the plants containing or receiving from the soil a greater
amount of alkaline and earthy phosphates than other plants obtain
in the same time, will also produce a greater number of seeds
than the latter.

Thus it is that, in a hot summer, when the supply of the con-
stituents of the soil is cut off by rain, the height and strength of
the plants, and the development of the seed, stand in exact pro-
portion to the quantity of the constituents of the soil taken up
during their former period of growth.

The produce of a field in corn and in straw varies very con-
siderably in different years. In one year we may obtain the
same weight of corn of similar composition to that obtained in
another year, but the crop of straw may be considerably greater ;

YjjH, ----- V RETROSPECT.

or the reverse may take place, and the crops of straw (of carbon)
may be equal, while the corn may amount to double the quantity.
But when we obtain twice the quantity of corn from the same
surface, we must have also a corresponding increase of the con-
stituents of the soil in the corn ; or, when we obtain twice the
quantity of straw, there must be twice the amount of the ingre-
dients of the soil in llie straw. In one year the wheat may be
3 feet in height, and yield I2t0 lbs. of seed per acre, while, in
another year, it may grow one foot higher, and yet yield only
800 lbs.

An unequal crop indicates, under all circumstances, an une-
qual proportion of the constituoiils of the soil taken up for the
formation of the corn and of the straw. Straw contains and
requires phosphates, as well as corn, but in much smaller pro-
portion.

In a wet spring, when the supply of these salts is not so great
as that of n!k -.iies, of silica, and of sulphates, the crop of seeds
becomes diinihisinMl ; because a certain quantity of the phos-
phates, which woL\ld otiu-rwise be employed in the formation of
the seeds, is now used for the production of the stem and lea^ves ;
the constituents of the seeds cannot be perfected without an
abundant supply of phosphates. By depriving a plant of these
salts, we could produce artificially the state iu which they attain
a height of three feet, and blossom without ihe production of
seeds. The crop of corn growing on a soil rich in the consti-
tuents of straw (a fat soil), is often less in a wet spring than upon
a soil poor in these ingredients (a thin soil), because the supply
of mineral food on the latter is greater in the same time, and is
in better proportion for the growth of all the constituents of plants
than in the former case.

On the supposition that all the conditions necessary to our cul-
tivated plants, for the assimilation of food from the atmosphere,
existed in the most favorable form, yet the action of humus would
be useful in effecting a more rapid growth of the plants, and
thus GAINING TIME, ill all cases, the crop of carbon is increased
by means of humus ; and if the conditions be absent for the eon-
version of this element into other constituents, it a9<«M»ifMM» the

AMOUNT OF NITROGEN IN DIFFERENT CROPS. 191

form of starch, gum, and of sugar, that is, of substances destv
^llte of mineral ingredients.

Every moment of time is of value in the practice of farming ;
and, in this respect, humus is of especial importance in kitchen
gardening.

Our corn plants and edible roots find in our fields, in the form
of the remains of a past vegetation, sufficient vegetable matter to
correspond to the mineral food existing in the soil, and, therefore,
with sufficient carbonic acid to produce a quick growth during
spring. Any further supply of carbonic acid would be wholly
useless, unless it were accompanied by a corresponding increase
of the mineral constituents adapted to form parts of the plant.
Upon a Hessian acre of good meadow land we obtain 2500 lbs. of
hay, according to the opinion of experienced farmers. Meadows
yield this crop, without any suj>ply of organic matters, '•r with-
out any manures containing nitrogen or carbon. By proper irri-
gation, and by treatment with ashes and gypsum, the crop can
be increased to double the amount. Let us assume, however,
that the 2500 lbs. of hay form the maximum crop ; still, it is
certain that all the carbon and nitrogen of the plants constituting
it must have been obtained from the air.

According to Boussingault, hay, dried at tlie temperature of
boiling water, contains 45*8 per cent, of carbon (a result agree-
ing with analyses made in this laboratory), and 1"5 per cent, of
nitrogen ; hay dried in air still retains 14 per cent, of water,
which escapes at the heat of boiling water.

2500 lbs. of hay, dried in air, correspond to 2150 lbs. of hay
dried at the temperature of boiling water. With the 984 lbs. of
carbon contained in the crop of 2150 lbs. of hay, we have also
removed from the acre of meadow-land 32*2 lbs. of nitrogen.
If we assume that this nitrogen has entered the plant in the form
of ammonia, it is obvious that for every 3640 lbs. of carbonic
acid (calculated at 27 per cent, of carbon) the air contains 39* 1
lb«. ammonia (taken at 82 per cent, of nitrogen) ; or that, for
every 1000 lbs. of carbonic acid, the air contains IO-j^q- lbs., am-
monia— a quantity corresponding to about -io-^oTo" ^^ ^^^® weight
of the air, or of -yo-Vo? of its volume.

Thus fcr every 100 parts of carbonic acid absorbea by tho

IW RETROSPECT

surface of the leaves of the meadow plants, there must also be
absorbed from the air above one part of ammonia. When we
calculate how much nitrogen different plants obtain from equal
surfaces of land, basing our calculations r»n known analyses, the
following results are obtained :

lbs. of carbon remove

in nitrogen-

-

From

meadow land, in hay

- 32-7

"

arable

land,

in wheat

-

- 21-5

u

i<

oats

-

- 22-3

•<

"

rye -

-

15-2

•<

•I

potatoes

-

- 341

"

•♦

mangel-wurzel

- 39-1

"

'*

clover

-

- 44

•<

(t

peas

-

- 62

These facts lead to certain conclusions of high importance to
agriculture. We observe, in fact, that the proportion of nitro-
gen absorbed, relatively to that of carbon, stands in a fixed rela-
tion to the surface of the leaves.

1. Plants containing nearly all their nitrogen concen-
trated IN THEIR SEEDS, SUCH AS THE CEREALS, CONTAIN ALTO-
GETHER LESS NITROGEN THAN THE LEGUMINOUS PLANTS, PEAS AND
CLOVER.

2. The crop of nitrogen from a meadow to which no

AZOTIZED manure HAS BEEN GIVEN, IS MUCH GREATER THAN THAT
>R0M a MANURED FIELD OF WHEAT.

3. The crop of nitrogen in clover or in peas is much
greater than that of a highly-manured field of potatoes
or of turnips.

Boussingault obtained in five yeaEs,-from his farm in Bechel-
bronn, Alsace, in tlie form of potatoes, wheat, clover, turnips, and
oats, 8383 carbon, and 250-7 nitrogen ; in the succeeding five
years,* 8192 carbon, 284-2 nitrogen ; in a third rotation of six
years,t 10949 carbon, 353"6 nitrogen ; or, in sixteen years,
27424 carbon, and 858-5 nitrogen ; or altogether, in the pro-
portion OF 1000 CARBON to 31-3 NITROGEN.

• Beet, wheat, clover, wheat, late turnips, oats, rye.
t Potatoes, wl»eat, clover, wheat, late turnips, peas, rye.

INOKGANIC MANURE. 193

A most remarkable and iinpo^rtant result follows from this ex-
periment — that when potatoes, wheat, turnips, peas, and clover
(roTASH, LIME, and silica plants), are cultivated successively on
the same field, altJKJUgh this field had been thrice manured in the
course of sixteen years, the »a»>e relation of nitrogen to a given
quantity of carbon is obtainet), ay in the case of a meadow which
had received no manure.

Carbon. Nitrogen.
Upon an acre of meadow land there is cropped of silica, > ^.q . ^q-.t

lin>e, and potash plants, taken together - - )
On an acre of arable land, on a sixteen years' average, of ) ^- - „

silica, lime, and potash plants - ' - } '^

When we take into consideration the amount of carbon and
nitrogen in tlie leaves of the beet and potatoe (for the leaves
were not calculated in the produce of the arable land), then it
follows that, notwithstanding all the supply of carbon and of ni-
trogen furnished in the manure, the arable land lias not produced
more of these elements than an ec^ual surface of meadow land,

WHICH RECEIVED ONLY MINERAL FOOD (cOllHtitUents of the Soil).

Then, on what depends the peculiar action of manures,
and of the liquid and solid excrements of animals ?

This question is susceptible of a simple solution. Tliese
manures have a very decided action on our arable land, from
which for conturi(\s we hnve removed, in the form of cattle and
of corn, a certain quantity of oorivStituents of the soil which have
not been restored.

If no manure hud been applieu to the land during the sixteen
years of tlic above experiTuent, the crop would have mounted to
only a half or third part of th? carbaa and nitrogen.

The liquid and solid excrements used as manure enabled this
surface of arable land to produce as much as the meadow land.

But notwithstanding the amount of manure supplied, the field
was no richer in the mineral f )od of plants on the sixth year,
when it was manured anew, than it was the first year. In the
second year after manuring, it contained less mineral food than
on the first year ; and after the fifth year it became so much ex-
hausted that it was necessary, in order to obtain crops as rich as
the first year, to give back to the field all the mineral constituents
10 . . , . ;

194 RETROSPECT.

that had been removed during the five years' rotation ; this was
done, without doubt, by means of the manure.

Our supply of manure, therefore, effects only this result, that
the soil of our arable land is not rendered poorer than that of
meadow land capable of yielding on the same surface 25 cwt. of
hay. From a meadow we remove annually, in the hay, as great
an amount of the constituents of the soil as we do in the crops
obtained from the arable land; and we know that the fertility of
meadow land is as dependent on the restoration of the constituents
of the soil, as that of arable land is upon the supply of manure.
Two meadows of equal surfaces, but containing unequal quantities
of inorganic food, are of unequal fertility under like circumstances.
The meadow containing the greatest quantity of the mineral food
yields more hay, in a certain number of years, than the other
which is poorer in mineral ingredients.

But if we do not restore to a meadow the constituents of the
soil removed from it, its fertility decreases.

The fertility of a meadow remains the same, not only by treat-
ing it with solid or with liquid excrements, but it may be retained,
or may be even increased in fertility by the application of mine-
ral substances left behind after the combustion of wood or of
other plants By means of ashes we can restore the impaired
fertility of our meadow land. But by the term ashes, we un-
derstand the mineral food which plants received from the soil.
When we furnish them to our meadows we enable the plants
growing on them to condense carbon and nitrogen on their surface.

Now, does not the action of liquid and solid excrements
depend on the same cause ? For these are but the ashes of

PLANTS BURNT IN THE BODIES OF MAN AND OF OTHER ANIMALS.

Is fertility not quite independent of the ammonia conveyed to
the soil ? If we evaporated urine, dried and burned the solid
excrements, and supplied to our land the salts of the urine, and
the ashes of the solid excrements, would not the cultivated plants
grown on it — the graminese and leguminosae — obtain their carbon
and nitrogen from the same sources whence they are obtained by
the gnimincos and leguminosae of our meadows ?

There can scarcely be a doubt with regard to these questions,
when we unite the information furnished by science to that sup-
plied by the practice of agriculture.

INORGANIC MANURE. 195

The following rotation is adopted in Alscce, as oeing the most
advantageous ; it extends over a period of five years, during
which the land is only once manured : —

1st Year. 2d Year. 3d Year. 4th Year. 5th Year. 6th Year.

Manured. Manured.

Oats, or

Wheat with Rye, or Potatoes

Potatoes or Wheat Clover Fallow turnips Barley.

Beet

Potash Silica Lime Silica > t), . Silica ^

Plants. Plant. Plant. Potash 5 P^^^^s j^^^^ j Plants,

Now, if we suppose that the action of the manure depends
upon its ammonia, or amount of nitrogen, then it is obvious that
a progressive diminution must ensue ; that the nitrogen in the
crops of the first and second years must amount to more than
that contained in the crops of the fourth and fifth years. But
this opinion is completely opposed to the following proportions, as
indicated by analysis : —

1st Year. 2d Year. 3d Year. 4th Year. 5tb Year.
Nitrogen in the crop - - 46 35*4 84*6 560 28-4

Thus, in the third and fourth years the nitrogen in the crops
amounted to much more than the quantity contained in the crops
of the first and second years ; and in the fifth year the quantity
was only one-fourth less than it was in the second year. Now,
is it possible or conceivable that the ammonia given in the first
year, being a body of great volatility and very apt to evaporate
along with water, could be present in greater quantity in the soil
during the fourth year than it was in the first and second years ;
or that it could yield to the oats of the fifth year the necessary
quantity of nitrogen for their growth ?

But let us admit that the nitrogen conveyed to the soil by
strong manuring was actually exhausted in the fifth year by the
different plants cultivated upon it ; and let us then compare the
rotation employed in Alsace, with that adopted on one of the
most fertile districts of the Rhine. In Bingen there is a nine-
years' rotation followed, the plants suc(jeeding each other in the
following order : —

19« RETROSPECT.

1st year. 2d Year 3d, 4th, 5th, 6th Years. 7th Year. 8th Year. 9th Year.

Manured. Manare<L

Turnips Barley with Lucern. Potatoes. Wheat. Barley.

Lucern.

Six years after manuring, after the supply of ammonia and
manure containing nitrogen, after four succeeding crops of clover,
and after a crop of barley and one of oats, the soil of Bingen
yields rich crops of potatoes, wheat, and barley, and these suc-
ceed each other at a time when, according to our assumption, the
manured field in Alsace was to be viewed as completely ex-
hausted of its nitrogen. Can it be conceived that the ammonia
of the manure could, after the lapse of 8 — 9 years, furnish the
nitrogen to the crops of wheat and barley ? But even admitting
this to be the case, we have then to inquire whence do the corn-
fields in Hungary, in Sicily, or in the vicinity of Naples, receive
their nitrogen, for these fields have never been manured ? Are
we actually to believe that the nutrition of plants in the fields
of moderate climates is subject to different laws from those
governing the warmer and tropical regions ?

In Virginia the annual crop of nitrogen in wheat amounted to
22 lbs. an acre, on the smallest calculation, or in 100 years to
2200 lbs. If we were to suppose that this nitrogen was fur-
nished by the field, each acre must have contained it in the form
of hundreds of thousand pounds of animal excrements !

The whole population of Limousin subsist upon milk and
sweet chestnuts, the production of which, being unattended with
trouble, is ascribed by Dupin as the cause of their low state of
intellect. Without being subjected to any system of farming,
this district produces enormous quantities of the constituents of
the blood, the nitrogen of which cannot have been produced from
manure.

For centuries, in Hungary, wheat and tobacco have been cul-
tivated on the same field, without any supply of nitrogen. Is it
possible that this nitrogen can have had its origin in the soil ?
Our forests of beeches, chestnuts, and oaks, become covered with
leaves every year ; the leaves, sap, the acorns, chestnuts, cocoa-
nuts, the fruit of the bread-tree, are rich in nitrogen. This
nitrogen is not contained in the soil, nor is it conveyed to the

EXPERIMENTS OF BOUSSINGAULT. 197

wild plants by the hand of man. Then it is impossible to doubt
the source whence the nitrogen is obtained. The source of the
nitrogen can only be the atmosphere. It matters not in what
form it is contained therein, or in what form it is taken from it ;
the conclusion is the same, that tlie nitrogen of wild-growing
plants must be derived from the atmospliere.

Are the fields of Virginia, the fields of Hungary, our own cul-
tivated plants, not able to receive it from the same sources as the
wild-growing vegetation ? Is the supply of nitrogen in animal
excrements a matter of absolute indifference : or do we obtain

IN OUR FIELDS A QUANTITY OF THE CONSTITUENTS OF THE BLOOD,
ACTUALLY CORRESPONDING TO THE SUPPLY OF AMMONIA ?

These questions are completely solved by the investigations of
Boussingault ; which are so much the more valuable, as they
were instituted with a totally distinct object in view.

From the known quantity of manure (common stable manure)
which Boussingault put every five years upon his field (amount-
ing to four Hessian acres), he estimated, by the analysis of the
manure, the total quantity of nitrogen furnished for the rotation
of five, years. For this purpose, the moist stable manure was
first dried by exposure to the air and to the sun, and afterwards
was further dried in vacuo, by exposing it to a temperature of
230^ F. ; the manure thus treated was subjected to an ultimate
analysis. The average crops of the field, treated with manure,
were then determined ; and the products, corn and straw, turnips,
potatoes, peas, clover, &c., were analysed for the purpose of
ascertaining their composition with reference io nitrogen, carbon,
hydrogen, and ashes.*

In this manner the quantities of nitrogen conveyed to the field
in the form of manure, and reaped from it in the crops, were
ascertained, and could be compared together. If the plants
depended for their nitrogen upon the manure, and did not receive
any of that element from the air ; the nitrogen of the crops could

* The greatest number of these analyses — viz. the composition of pota-
toes (Boeckmann) ; of beet and turnips (Will) ; of wheat straw (Will) ;
of the carbon and nitrogen of peas (Noll and Zytowieki) ; and of their
carbon (Playfair), were repeated in this laboratory, and ascertained U
be perfectly correct.

©8 RETROSPECT.

not correspond to more than the quantity in the manure. If the
crops contained more than this quantity, the excess must have
been obtained from other sources, and these could only be in the
atmosphere ; such were the suppositions on which Boussingault
proceeded. According to his estimation, the three rotations*
yielded : —

1st Rotation. 2d Rotation. 3d Rotation. In 16 years.
Nitrogen in lbs. - - - 501-4 508'4 7072 17170
in stable manure - 40G-4 406-4 487-6 1300-4

Excess of nitrogen obtained, lbs. 95 102 2196 416*6

In the first and second rotation, the excess of nitrogen obtained
was nearly equal ; in the third it was twice as much.

Now, asked Boussingault — did each of these plants possess the
power of absorbing and appropriating to their organism nitrogen
from the air, or was this power confined only to one of them ; and
was the excess of nitrogen due to all the various kinds of plants,
or was it yielded by only one of them ? A new experiment
seemed to him to decide the question. Two successive crops of
corn were taken from a fallow-field, well manured, and the pro
duce amounted to : —

Nitrogen in the crops - - . ] 74-8 lbs.
■ the manure - - - 165-6

An excess of nitrogen - - 9*2 lbs.

But this excess in the crop is too small not to be liable to errors
in the experiment. Boussingault concluded from it, that cereals
do not absorb nitrogen from the air, and that the amount of nitro-
gen yielded in crops is only equivalent to that contained in the
manures.

Now, as it had been found that the quantity of nitrogen ob-

Ist Rotation.

2d Rotation.

3d Rotation.

1

Ye3x

Potatoes

Beet

Potatoes

2

"

Wheat

Wheat

Wheat

3

((

Clover

Clover

Clover

4

(1

Wheat >
late Turnips )

Wheat

1

Wheat
late Turnips

late Turni

ps

5

«<

Oats

Oats

Peas

0

«(

Rye

EXPERIMENTS OF BOUSSINGAULT. 199

tained in crops of potatoes and turnips scarcely corresponds to
more than the quantity in crops of wheat, it follows that they
could not have tlie power to form their azotized constituents with-
out manure ; so that nothing remains, except to ascribe to the
clover the excess of nitrogen obtained. This explains, also, why
the excess is so much greater in the third rotation than in any of
the preceding ; for it will be remarked, that in the third rotation
a sixth crop was introduced, corresponding to the same family as
clover. If, therefore, there had been neither peas nor clover in
the third rotation, but, instead of these plants, one of another
family, the nitrogen of the crop would have amounted only to the
quantity supplied in the manure. Boussingault concludes that
leguminous plants alone possess the power of appropriating, as
food, nitrogen from the air, and that other cultivated plants do not
at all possess this property. Hence the great importance which
Boussingault ascribes to manures containing nitrogen, for, ac-
cording to his view, the commercial value of a manure depends
on its amount of nitrogen. But all these conclusions are tho-
roughly erroneous; for, if they were not so, it must follow that
potash, lime, and silica plants, unless they belonged to the Legu-
minosse, would not produce any nitrogen, unless they were sup-
plied with manure containing that element.

The conclusions of Boussingault are not only erroneous in their
applications to agriculture, but are incorrect in the methods
which he employs ; for the manure was not given to the fields in
the form in which he analysed it.

Let us assume that the manure which he put upon his fields
possessed the same state in which it was analysed (dried at
230^ F. in vacuo) ; then the field would receive in the sixteen
years 1300 lbs. of nitrogen. But the manure was not put upon
the field in an anhydrous state, but, on the contrary, in its natu-
ral moist condition, soaked with water ; and we know that all the
nitrogen contained in the manure in the form of carbonate of am-
monia is volatilized when it is dried at a high temperature. The
nitrogen of the urine in the manure, which is converted by putre-
faction into carbonate of ammonia, is not included in the 1300 lbs.
of the above calculation.

Human excrements, dried in the air at ordinary temperature

2-jl) RETROSPECT.

(poudrette), lose, at 230^, half of all the nitrogen contained in
them, in the form of carbonate of ammonia. Common stable ma-
nure, which contains 79 — 80 per cent, of water, must lose, when
heated to 230° in vacuo, at least three times as much nitrogen
as it retains ; that is, 3-4ths of all the nitrogen originally present
in it. But if we estimate it at haif of the quantity present in the
dried excrements, then the field must have received, in sixteen
years, 1950 lbs. of nitrogen.

But in sixteen years, 1517 Ihs. of nitrogen only were ob-
tained, IN THE FORM OF CORN, STRAW, AND TUBERS ; mUch less,

therefore, than the quantity furnisherl to the field. Hence his
erroneous conclusion, that the. Leguminosas alone possess the
power of condensing nitrogen from the air ; and tliat it is neces-
sary to furnish nitrogen to tiio Grtuulneae, aixl to plants such as
turnips and potatoes. Rut in the same time, and upon the same
surfiice of a good meadow, not receiving nitrogen, we may obtain
(on 1 hectare) 2060 lbs. of this element.

It is well known that dried excrements form the principal fuel
in Egypt, where wood is scarce. For centuries the sal ammo-
niac used in Europe was supplied from tiie soot of these excre-
ments, until Gravenhorst, in the latter part of last century,
discovered how to prepare it, and ijastituted a manufactory at
Brunswick.

The fields in the valley of the Nile re-ceive no manure of ani-
mal origin except the fixed ingredients (which contain no nitro-
gen) of the ashes of the burnt dung; and yet these fields have
been so fertile, for periods long before our history commences,
that this fertility has become a proverb, and is quite as remarkable
at the present day as it was in former times. These fields be-
come renovated by the mud deposited during the inundations of
the Nile ; the mineral ingredients of the soil removed in the crops
are thus restored to it. The mud of the Nile contains as little
nitrogen as the mud from the Alps, in Switzerland, deposited on,
and fertilizing our own fields by the inundations of the Rhine.

In fact, if the mud of the Nile fertilizes the soil, in consequence
of its containing nitrogen, we must suppose immense strata of
nitrogenized animal and vegetable matter to exist in the mountains
of the interior of Africa, at heights above the line of perpetual

REVIEW 0[^ PRECEDING THEORIES. 201

congelation, where, owing to the absence of all vegetation, no ani.
mal, not even a bird, can now find nourishment.

Cheese must be formed from the plants upon which cows feed.
The meadows of Holland must, of course, obtain their nitrogen
from the air. The milch cows in Holland remain on the fields
both day and night ; all the salts contained in their fodder
must remain upon the fields in the form of urine and of solid
excrements, a small quantity proportionately being removed in
the cheese.

The condition of fertility of these meadows can change as little
as that of our fields, which, although not grazed upon, receive, in
the form of manure, the greatest part of the ingredients removed
from them.

In the cheese districts of Holland, these ingredients remain on
the meadows ; while in our system of farming, they are collected
at home, and carried, from time to time, to our fields. The ni-
trogen of the urine, and that of the solid excrements of the cow,
are obtained in Holland from the air ; and from the same source
must be obtained the quantity of that element contained in all
the kinds of cheese prepared in Holland, Switzerland, and other
countries.

The meadows in Holland, for centuries, have produced millions
of cvvts. of cheese : there are annually exported from this country
thousands of cwts. of this substance ; and yet this exportation
does not in any way diminish the productiveness of their meadows,
although they have never received from the hand of man more
nitrogen than they originally contained.

Hence it is quite certain, that in our fields, the amount of nitro-
gen in the crops is not at all in proportion to the quantity supplied
in the manure, and that the soil cannot be exhausted by the ex-
portation of products containing nitrogen (unless these products
contain at the same time a large amount of mineral ingredients),
because the nitrogen of vegetation is furnished by the atmosphere,
and not by the soil. Hence also we cannot augment the fertility
of our fields, or their powers of production, by supplying them
with manures rich in nitrogen, or with ammoniacal salts alone,
The crops on a field diminish or increase in exact proportion t<>'
10* . - " ^

• 202 REVIEW OF PRECEDING THEORIES.

the diminution or increase of the mineral substances conveyed to
it in manure.

The formation of the constituents of the blood, and of the vege-
table substances containing nitrogen existing in cultivated plants,
depends upon the presence of certain substances contained in the
soil. When these ingredients are absent, nitrogen will not be
assimilated, however abundantly it may be supplied. The am-
monia of animal excrements exerts a favorable influence only
because it is accompanied by other substances necessary for its
conversion into the constituents of blood. When these conditions
are furnished with ammonia, the latter becomes assimilated. But
when the ammonia is absent from the manure, the plants extract
their nitrogen from the ammonia of the air ; to which it is again
restored by the decay and putrefaction of dead animal and vege-
table remains.

Ammonia accelerates and favors the growth of plants on all
kinds of soil, in which exist the conditions for its assimilation ;
but it is quite without action upon the production of the consti-
tuents of the blood, when these conditions do not exist.

It is possible to conceive that asparagin (the active ingredient
of asparagus) and the ingredients so rich in nitrogen and sulphur,
oC mustard and of all Cruciferse, could be generated without the
co-operation of the ingredientsof the soil. But if it were possible
to form the organic constituents of blood existing in plants, with-
out the aid of the inorganic ingredients of the blood, such as
potash, soda, phosphates of soda and of lime, they would be of
very little use to animals, and could not fulfil the purposes for
which they were destined by the wisdom of the Creator. Blood,
milk, and muscular fibre cannot be formed without the aid of
alkalies and of phosphates ; and bones cannot be produced without
phosphate of lime.

In urine, and in the solid excrements of animals, and in guano,
we furnish ammonia, and therefore, nitrogen, in our plants.
This nitrogen is accompanied by the mineral food of plants, and
actually in the same proportion as both exist in the plants which
served the animals for food ; or, what is the same thing, in the
same proportion in which both are capable of being applied for a
new generation of plants.

REVIEW OF PRECEDING THEORIES. 30a

The action of an artificial supply of ammonia as a source of
nitrogen, is limited, like that of humus as a source of carbonic
acid, to a gain in point of time ; in other words to the ac-
celeration of the development, in a given time, of our cultivated
plants.

By means of ammonia, in the form of animal excrements, we
increase the quantity of the constituents of blood in our cultivat-
ed plants — an action which the carbonate or sulphate of ammonia
alone never exerts.

In order to obviate any misunderstanding, we must again draw
attention to the fact that this explanation is not in any way con-
tradicted by the effects produced on the application of artificial
ammonia, or of its salts. Ammonia is, and will continue to be
the source of all the nitrogen of plants : its supply is never in-
jurious ; on the contrary, it is always useful, and, for certain
purposes, indispensable. But, at the same time, it is of great
importance for agriculture, to know with certainty that the sup-
ply of ammonia is unnecessary for most of our cultivated plants,
and that it may be even superfluous, if only the soil contain a
sufficient supply of the mineral food of plants, when the ammonia
required for their development will be furnished by the atmo-
sphere. It is also of importance to know, that the rule usually
adopted in France and in Germany of estimating the value
of a manure according to the amount of its nitrogen, is quite
fallacious, and that its value does not stand in proportion to its
nitrogen.

By an exact estimation of jhe quantity of ashes in cultivated
plants, growing on various kmds of soils, and by their analysis,
we will learn those constituents of the plants which are variable,
and those which remain constant.* Thus also we will attain a

* The following analyses of ashes may be added to those formerly given :

Ashes of Clover

Ashes of

(TrifoUum pratense).

Sainfoin.

Silica -

- 5 -438

2-79

Sulphate of potash

- 3080

3-87

Chloride of sodium

- 1-670

2-37

Carbonate of potash

- 12-728

9 93

Carbonate of soda

- 13-528

1716

Carbonate of lime

- dS-91d

3255

204 REVIEW OF^ PRECEDING THEORIES.

knowledge of the quantities of all the constituents removed from
the soil by different crops.

The farmer will thus be enabled, like a systematic manufac-
turer, to have a book attached to each field, in which he will
note the amount of the various ingredients removed from the land
in the form of crops, and therefore how much he must restore to
bring it to its original state of fertility. He will also be able to
express in pounds weight, how much of one or of another ingre-
dient of soils he must add to his own land, in order to increase its
fertility for certain kinds of plants.

These investigations are a necessity of the times in which we
live ; but in a few years, by the united diligence of chemists of
all countries, we may expect to see the realization of these views ;
and by the aid of intelligent farmers, we may confidently expect
to see established, on an immovable foundation, a rational system
of farming for all countries and for all soils.

Ashes of Clover

Vshes of

( Trifolium pratcnse.)

Sainfoin.

Magnesia - - -

- 4-160

911

Phosphate of iron

- 1-240

0-64

Phosphate of lime

- : 1-970

15-37

Phosphate of magnesia

- G-790

3-9S

Carbonaceous matter -

- 0-160

0-36

98-980 98*13

SGORCES OF AMMONIA. 20S

SUPPLEMENTARY CHAPTERS.

I. — The Sources of Ammonia.

When animals appeared on the surface of the earth, it cannot be
doubted that means must have been provided for their sustenance
and increase, or in other words, that plants must have existed to
furnish them with food. But it is quite as obvious that, at the
period of the formation of the vegetable world itself, the condi-
tions must have existed in the soil and in the atmosphere, neces-
sary for the exercise of vegetable life. With the same certainty
with which we presuppose the existence of a compound of carbon
to furnish that element to vegetation, we must also assume the
contemporaneous presence of a compound of nitrogen, such as at
the present day yields that element to plants.

If we disregard the fundamental principle on which all
inquiries into nature ought to proceed, then we may assume,
a priori, according to our will and pleasure, that other compounds
of carbon, differing from carbonic acid, formerly took part in the
vital processes of plants ; but if we still retain the foundation of
all scientific inquiry, namely, induction from facts, then we can-
not admit the existence of these hypothetical compounds of car-
bon, either because they are totally unknown to us, or that their
existence is doubtful.

The same reasoning must be adopted in the case of nitrogen.
Science is at present ignorant of any compound of nitrogen be-
sides ammonia, capable of yielding nitrogen to wild plants on all
parts of the earth's surface. No other such compound of nitrogen
has been indicated, or even hypothetically supposed to exist, and
designated by a name, in the case of cultivated plants ; and there-
fore, until a second source of nitrogen is discovered, we must, ill:
scsience^-yiow. ammonia a& tlie on?v-, sou roe.- . ... ' ., r

906 SOURCES OF AMMONIA.

Now, it may be asked, Is there no means of increasing the
amount of ammonia which exists in the atmosphere, as well as
in the form of plants and animals, and which we shall assume to
be a limited quantity ? This question may be repeated in another
form, viz. Whether there exist undoubted facts for the opinion
that the nitrogen of the air possesses, under any condition, the
power of assuming the form of ammonia, or of any other com-
pound of nitrogen ? Besides nitric acid and ammonia, we do
not know any other compounds of nitrogen, except those exist-
ing in plants and animals, or which may be prepared from them.
With the exception of these compounds, nitrogen exists only in
the form of a gas, which has been recognised as one of the prin-
cipal constituents of air.

An ignorance of the proper sources whence vegetation receiv-
ed its nitrogen, led philosophers long since to the opinion, that
plants must possess the power, in some way or another, of appro-
priating the nitrogen of the air in their vital processes. In fact,
until it was known that ammonia formed a constituent of the air,
there was scarcely any reason to doubt this power of plants ; for
how otherwise were wild plants to obtain the nitrogen of their
azotized constituents ?

But ammonia was known and considered only as a product of
the destruction and decomposition of the organism. The pro-
duction and formation of ammonia presupposed the existence of
plants or animals. Hence there have arisen two views respect-
ing the origin of ammonia, the correctness of which we have as
little means of establishing by decisive evidence, as we have of
answering the questions — Whether the hen existed before the
egg, or the egg before the hen ; or whether water was first creat-
ed as water, or as hydro jjen and oxygen ? We have sufficient
reason to believe that the vegetable preceded the animal kingdom ;
and we assume, that before plants were formed, the conditions
essential for their life and increase must have existed ; and that
then, as well as now, ammonia must have been a constituent of
the air ; and that the destruction of plants did not precede the
formation of ammonia. Now, it is obvious that if the same
causes now continue in action, as those which effected the forma-
ts of ammonia at the commencement of vegetation,— if their

FORMATION OF MATTER. 207

action resulted in the conversion of the gaseous nitrogen into
ammonia, — then, at the present day, during every moment, am-
monia must be forming, and the amount of that previously exist-
ing will be increased. It is natural to the mind of man to
ende-avor to solve questions of this kind, however small may be
the expectation of success. It is known that the crust of the
earth consists of compounds of oxygen with metals or with other
radicals ; and the view appears quite admissible, that silica has
been formed from silicon and oxygen ; peroxide of iron from
iron and oxygen ; and, to follow up the idea, magnesia and potash
have been produced from oxygen, magnesium, and potassium.
And yet it is utterly impossible to assign a cause which prevent-
ed the union of the oxygen with potassium or magnesium before
the time that this combination actually took place. Was there,
it may be asked, a time when the individual elements floated to-
gether in Ghaos, without possessing any kind of affinity ? In
what condition then was the chlorine of common salt or the carbon
of carbonic acid ? It is obvious that no answers can be given to
questions respecting the origin of matteri If, then, we are una-
ble to afford any more satisfactory explanation of the origin of
ammonia, than we are able to do of the other compounds occur-
ring upon the earth, we must rest satisfied that these questions
will either never be solved, or that they will not be so until a
future period.

The ferruginous earths in the primitive rocks of South Ame-
rica (Boussingault), and of Sweden (Berzelius), — in fact all
ferruginous earths hitherto examined, — yield, on being heated,
a certain amount of water containing appreciable quantities of
ammonia. Whence has this ammonia had its origin ? Accord-
ing to the logic of Aristotle, the occurrence of ammonia in the
ferruginous earths was susceptible of a satisfactory explanation.

We may assume that water is the only original compound of
hydrogen occurring in nature ; other bodies containing that ele-
ment are products of the decomposition of water, from which
they have procured this hydrogen.

Ammonia has been formed like other compounds of hydrogen ;
the ferruginous eaith was formerly iron, which we may suppose
to have becdme oxidized at the expense of wator, in which cas©

908 SOURCES OF AMMONIA.

peroxide of iron would be formed, and hydrogen become liberat-
ed. Now, if we assume that hydrogen, at the moment of its
liberation, is able to unite with nitrogen gas in contact with it,
and dissolved in water, then ammonia would be produced, and
would remain in union with the peroxide of iron. It is certain
that this explanation of the origin of ammonia in peroxide of
iron would be perfectly satisfactory, if it were ascertained
with some degree of probability that peroxide of iron has
had its origin by oxidation at the expense of water, and that
the nitrogen of air is capable of uniting with hydrogen at
the instant of its liberation. On this view we might suppose,
that although there was a limit to the formation of ammonia,
under former conditions, when ferruginous earth was produced,
that by the simultaneous occurrence of the same or of analogous
conditions at the present day, ammonia might still be produced.

But the decomposition of water, by means of iron, is effected
under such circumstances as appear to exclude the simultaneous
production of ammonia.

Iron does not decompose water at the ordinary temperatures,
and at higher temperatures — at the boiling point of water, for
example — nitrogen does not remain any longer in solution. When
a stream of nitrogen is made to pass along with water over iron
filings heated to redness, the nitrogen is again obtained unaltered
although it be mixed with hydrogen. It is easily explained why am-
monia cannot be formed in this case, for ammoniacal gas in contact
with iron at high temperatures, is decomposed into its constituents.

When finely divided hydrate of peroxide of iron is placed in
contact with metallic iron, a decomposition of water takes place
at a slightly elevated temperature, and hydrogen gas is evolved,
while magnetic oxide of iron is produced. As hydrated peroxide
of iron acts as an acid in this case, we should here, as indeed
universally, when metals are dissolved in acids with the evolution
of hydrogen, obtain in the solution a salt of ammonia, if ammonia
had been formed.

But hitherto the presence of ammonia under the circumstances
has not been detected ; and it has further been shown satisfactorily,
that when water holding air in solution is decomposed by a stream
of electricity, the hydrogen evolved is accompanied by a certain

RELATION OF NITROGEN TO HYDROGEN. 2«i

quantity of nitrogen gas, which could not be the case if nascent
hydrogen were able to form ammonia.

It has been considered as a certain proof of the formation of
ammonia from the nitrogen of the air, that peroxide of iron,
formed by the rusting of iron in the air, contains a certain quan-
tity of ammonia ; but air itself contains ammonia, which pos-
sesses a considerable affinity for peroxide of iron. Marshall
Hall has shown the inaccuracy of the view that water is decom-
posed in this case ; and further experiments, instituted in this
laboratory for the especial purposeof deciding this question, have
shown, that when air is freed from its ammonia, by being con-
ducted through concentrated sulphuric acid, before being brought
in contact with the rusting iron, the oxide then formed does not
contain a trace of ammonia.

Braconnot* has shown that most basalts, trap, granite from
Rochepon, and from Bresse ; syenite, amphibolite, wakit (a lava) ;
basalt, from Baden ; quartz, from Gerordines ; pegmatite, and
many other minerals, yield, by dry distillation, water containing
a sensible quantity of ammonia.

These facts cannot be explained by the interpretation above
given to the occurrence of ammonia in ferruginous earth, namely,
the oxidation of iron at the expense of water ; but there cannot
be any doubt that the ammonia has had a similar origin in all
these cases, although that origin cannot be ascribed to an oxida-
tion of iron.

The question — whether the nitrogen of the air possesses the
power of uniting with hydrogen at the moment of its liberation
from water ? has been lately made the subject of exact experi-
ments, although with very different objects in view. Will and
Varrentrapp applied to the quantitative estimation of nitrogen in
organic bodies the known fact, that the nitrogen of bodies con-
taining that element is evolved in the form of ammonia, when
they are heated to redness, mixed with potash. By combining
the ammonia with an acid, and converting it into the salt termed
chloride of platinum and ammonia, the ammonia generated may
be weighed with ease, and the quantity of nitrogen may
be calculated from the known composition of this salt. A groat
* Annales de Chimie et de Physique, tome Ixvii., p. 104, k,c.

^^0 SOURCES OF AMMONIA.

number of analyses of compounds, in which the quantity of ni-
trogen was known, showed that this mode of procedure answered
completely the object in view ; until certain experiments by
Reiset were published, in which he obtained ammonia by this
process from substances such as sugar, &;c., which were quite
destitute of nitrogen. Reiset, therefore, assumed that the nitro-
gen of air contained in the pores of the mixture was the cause of
the formation of ammonia, and that, unless this air were excluded,
the method of analysis was incorrect and objectionable.

New experiments, repeated with the utmost care by Will, have
shown that in circumstances similar to those formerly observed
by Faraday, ammonia is actually obtained from matters destitute
of nitrogen, when they are heated to redness with potash ; but
that, by excluding ammonia itself, nitrogen cannot be made ,to
unite with hydrogen in a nascent state, and that ammonia can-
not be produced from these elements.

The admirable experiments of Faraday (Quarterly Journal of
Science, xix., p. 16) prove that, in all the cases in which ammonia
was obtained by heating to redness a substance destitute of nitro-
gen with hydrate of potash, the ammonia existed ready formed
in the substance, or in the hydrate of potash. There are no ob-
servations more convincing of the extraordinary diffusion of am-
monia, which exists in all places where atmospheric air is to be
found. That the reader may judge properly of Faraday's experi-
ments, I consider it important to describe them here in detail.

After Faraday had observed that woody fibre, linen, oxalate of
potash, and a number of other substances free from nitrogen,
evolved ammonia on being heated with soda, potash, hydrate of
lime, &c., he endeavored to ascertain the conditions under which
the formation of ammonia ensued ; and in the first place, he ex-
amined the alkalies. Hydrate of potash, whether made from
potashes, cream of tartar, or potassium, behaved exactly in the
same manner. The organic substances, when heated alone, had
no reaction on turmeric ; but when heated with the alkalies, a
disengagement of ammonia ensued.

It was then to be supposed that the nitrogen of the air sur-
rounding the substances might take a part in the formation of
ammonia : but this was very improbable : for it is known that

FARVDAY'S EXPERIMENTS. Htl

the air contains oxygen, whicii was never observed to unite with
the liberated hydrogen undor the same circumstances, although
its affinity for that element is infinitely greater than for nitrogen.

According to this supposition, the nitrogen of the air must
have formed ammonia by uniting with the hydrogen of the
decomposed water, although at tiie same time there was present
oxygen, for which hydrogen has a much greater affinity.

The experiments were repeated in an atmosphere of pure hy-
drogen, prepared from water which was previously freed from
all air by long-continued boiling. But in this case also, where
all nitrogen was excluded, the presence of ammonia was observed.
Hence, Faraday concluded that there must be an unknown
cause of the formation of ammonia.

Now, when it is known that ammonia is a constituent of the
air ; that it is present wherever the air is found ; that it is itself
a coercible gas, which is condensed on the surface of solid bodies
in much larger proportion than air; and further, when it is
known that it exists in distilled water, these, and other still more
incomprehensible experiments of Faraday, are explained in a very
simple manner.

Fine and bright iron wire, introduced into fused potash, causes
the evolution of ammonia, which soon ceases ; but a new evolu-
tion takes place when a second portion of polished iron-wire is
introduced (Faraday).

Zinc introduced into potash in a state of fusion, occasions an
immediate evolution of ammonia and hydrogen gas ; but althougii
the conditions for the possible formation of ammonia continue
(zinc, air, and nascent hydrogen), the quantity of ammonia gene-
rated does not increase ; but, by the addition of fresh zinc, or
of hydrate of potash, a new quantity of ammonia may be
detected.

Some potash and zinc were heated together ; a part of the mix-
ture was then placed in a flask, which was immediately closed,
while another part was dissolved in water, the clear solution dried,
and laid aside for 24 hours. After this time had elapsed, the
first portion j:ave scarcely perceptible t; aces of ammonia. The
Other gave very appreciable indications of its presence, apparently

213 SOURCES OF AMMONIA.

OS if the substances which were the source of ammonia were
derived from the air, during the operation (Faraday).

White clay from Cornwall, after being heated to redness and
exposed for a week to the air, yielded ammonia abundantly, when
heated in a tube. But when the clay was preserved in a good
stoppered bottle, after being heated to redness, this effect was not
produced.

Tlie observations which proved most undoubtedly that in all
these cases the ammonia was obtained from the air and condensed
on the surface of these materials, are the following (Faraday) : —

Sea-sand was heated to redness in a crucible, and allowed to
cool on a plate of copper ; 12 grains of the sand were then
placed in a clean glass tube ; and an equal quantity, shaken upon
the hand, was allowed to remain there for a i^ew moments, being
stirred about with the fingers, after which it was introduced into
a second tube by means of platinum foil, taking care that the
grains of sand were not brought in contact with any othijr animal
substance (Faraday).

When the first tube was heated, it gave no sign of ammonia
to turmeric paper ; but the second tube did so in very appreciable
quantity. For the sake of precaution the tubes used in these
experiments were not cleansed by tow or cloth, but unused tubes
were taken, and before being employed they were heated to
redness in a stream of air (Faraday).

Some asbestos heated to redness, and introduced into a tube
with metallic tongs, gave, when heated, no indication of ammonia ;
while, on the contrary, another portion, which had been simply
pressed with the finger, yielded immediate indications of am-
monia when heated in a tu[>e (Faraday).

Now it is known that ammonia evaporates by the skin, that
sweat contains salts of ammcnia ; and nothing can be more certain
than that, in the experiments last described, and also in those of
the burnt sand exposed to air, ammonia must have condensed on
the surface of the sand or of the asbestos.

These experiments explain in a natural manner the existence
of ammonia in earth from which plants and animals are entirely
absent, and also of the formation of nitre in mixtures of earth*
containing vegetable matter.

FARADAY'S EXPERIMENTS. '««

All observations in our times lead to the conclusion that the
nitrogen of the air does not possess the property of being con-
verted into ammonia ; and, whatever reasons there may exist for
the probability of this conversion, we are by no means entitled
to elevate to the rank of a principle the mere opinion that a part
of the nitrogen of plants arises from this source, as it is an hy-
pothesis standing in complete contradiction to all the knowledge
which we have yet attained.

All experiments which appear to piove that the nitrogen of the
air becomes fixed in the organism of certain plants, — that peas
and beans, for example, vegetating in a soil perfectly destitute of
animal matters, must possess the power of appropriating the ni-
trogen of the atmosphere, — cannot now have the smallest value,
when it is known that the air contains ammonia as a constant
ingredient. It must be recollected that these experiments were
instituted in districts in which the atmosphere is much richer in
ammonia than in the free fields, and that the distilled water, with
which the plants were treated, was obtained from spring-water,
and contained a much larger quantity of carbonate of ammonia
than rain-water. Hence, there is no reason to ascribe the in
crease of nitrogen in the seeds, leaves, and stems, to a source
which was only imagined to exist, because the quantity of am-
monia in the water and air was not considered, and the founda*
tion, therefore, of the true explanation was altogether wanting.

Chemical experiments have shown that ammonia is not only the
product of the decay and putrefaction of animal bodies, but thai
it is also capable of being generated in many chemical processes,
when nitrogen, at the moment of its liberation from compounds
containing it, is offered to hydrogen ; in such a case, they unite
together and form ammonia.

Compound gases containing nitrogen as a constituent (cyanogen,
nitric oxides, nitrous oxides), are converted into ammonia when
they are mixed and conducted ever spongy platinum heated to
redness (Kuhlmann), or over peroxide of iron (Reiset).

When steam is conducted over red-hot wood charcoal contain-
ing nitrogen, there is obtained, among other products, hydrocyanic
•acid, which is converted into ammonia and formic acid when
treated with alkalies.

914 IS NITRIC ACID FOOD FOR PLANTS ?

The nitrogen of nitric acid, when placed in contact with hydro-
gen at the moment of its liberation, as in the solution of tin, or by
fusing nitrates with potash and organic substances, is converted
into the compound of hydrogen. In all cases in which we expose
to a high temperature a body containing nitrogen and caustic
potash, its nitrogen assumes the form of ammonia.

The nitrogen of an organic body, of vegetable or animal mat-
ter, or of the charcoal produced from them, arises from the am-
monia which the plant contained and abstracted from the atmo-
sphere : it enters, in the processes of decomposition alluded to, into
its original form, and assumes the condition of ammonia.

But these instances cannot be cited as proper examples of the
formation of ammonia, nor can they be considered with reference
to the question which we have now been discussing.

IS NITRIC ACID FOOD FOR PLANTS?

Before we can examine the opinion whether nitric acid be a
means by which nitrogen is furnished to plants in nature, it is
most important to consider the origin of nitric acid.

At the request of the French Government, the Academy of
Sciences of Paris, in »he year 1770, offered a prize for the best
treatise on the formation of nitric acid and its production in arti-
ficial nitre-beds. The judges appointed by the Academy, includ-
ing Lavoisier, subjected to trial 70 treatises, the results of which,
after the experience of 50 years, were stated in a small work
published by Gay Lussac, in the year 1825,* in the following
sentences : —

1. " All the nitrogen necessary for the formation of nitric acid
is yielded to it by animal matter."

2. "Nitre is never generated from the air in substances

• Instruction sur la fabrication du salpitre, publii par la Commi$$ion
de» poudres et salpitres, 1825

FORMATION OF NITRE. 319

adapted for its formation, without the co-operation of anima.
matter."

This result of very numerous and correct experiments contra-
dicts completely the view that nitre may be generated in mixtures
of earth destitute of animal matter, and therefore at the expense
of the constituents of the air. The advocates of this view cite in
defence of it the following experiments : — When earth forming
nitre is freed from all its soluble salts by lixiviation, and is then
exposed for several years to the action of the air, it yields a se-
cond crop of nitre, and these crops may be obtained three or four
times in succession, although in different proportions. The ad-
vocates of this theory, considering that all the substances con-
taining nitrogen are removed, argue that the nitrogen of the nitre
formed afterwards, must have been derived from the air. But
this conclusion is opposed to all rules of inductive science. When
a known cause produces the same action in all cases submitted
to examination, we must revert to the same cause in considering
the same action in cases not examined ; for we have no right to
assign to it a new cause, in order to save us the trouble of a
closer investigation.

The advocates of the opinion that the nitrogen of the air is con-
verted into nitric acid in the nitre-beds, have never estimated the
amount of substances containing nitrogen existing in those beds ;
and they have never compared with this amount the quantity of
nitric acid actually generated. Those who, like Gay Lussac,
have taken this trouble, found that the quantity of nitric acid
formed corresponded to the quantity of animal matters present in
the mixture ; less nitre being formed, when the amount of the
latter was decreased, and by its increase, a greater quantity of
nitre was produced.

Another reason for the opinion was, that nitrates were formed
in certain limestone caverns in Ceylon, where, according to Dr.
Davy, nitrates of potash and lime occur in a limestone containing
felspar, but quite destitute of animal matter. But the latter as-
sertion is very questionable, as there is scarcely a limestone in
existence that does not yield ammoniacal liquid on being subjected
to distillation. An experiment with materials expressly prepared
ibr this purpose (carbonate of lime, felspar, and water free from

216 IS NITRIC ACID FOOD FOR PLANTS ?

ammonia), and conducted in this cavern, in order to see whether
nitric acid would be formed, would have completely decided the
qucetion, if nitric acid had been found in the mixture after a cer-
tain time ; but this experiment was not made, neither was the
water which filtered through the roof of the cavern subjected to
examination. The conclusion that nitric acid is formed in these
cases, at the expense of the nitrogen of the air, is not in any way
confirmed — it is only certain that the cause of the formation
of nitre in these caves remains unknown to those who have ex-
amined them.

It often happens that the well-water of towns contains a con-
siderable quantity of nitre which does not exist in the wells and
springs outside the towns. Berzelius detected nitrates in the well-
water of the city of Stockholm. Margraf also mentions its ex-
istence ; and I, myself, have shown the presence of nitrates in
the waters of twelve wells in the town of Giessen,* although they
could not be detected in the waters of six wells separated 2300
paces from the town. Animal matter, in a state of decay and
putrefaction, existed abundantly in the soil in all the places where
nitrates were found, and its nitrogen was converted into ni-
tric acid wherever the conditions for this conversion were found
united.

A large proportion of the nitre used in France, for the manu-
facture of gunpowder and for other purposes, is obtained at Paris.
The manufacturers of nitre use in its preparation the lower par's
of old broken-up houses, which have been in constant contact
with the liquids of the street. Nitre exists in large quantity in
the lower parts of houses, while the upper parts do not contain a
trace of it.

It cannot be denied that plants grow more powerfully and
luxuriantly in a soil capable of forming nitre, than they do in a
soil unfit for its formation.

The favorable influence of such a soil on vegetation is justly
ascribed to the animal matters contained in it, to the alkalies, and
to the phosphates existing in the animal matter. Out of the ani-
mal matter also, is formed the ammonia so necessary for the sup-

• Annates de Chimie et de Physique, vol. xxxv., 232.

FORMATION OF NITRE. 2x1

port of vegetation, and without the presence of wKich nitric acid
could not be formed. ,.v . •

The presence of alkaline nitrates in a soil indicates with the
greatest certainty, that the most important conditions for the
growth of plants are united in it ; but these salts are not the pri-
mary causes of the growth, because both the formation of nitre,
and the luxuriant growth of plants, are effects of similar causes
acting on the earth. It is certain that the vicinity of the saltpetre
mines of Quarta Jaga and Santa Rosa, described by Darwin,
although saturated with nitrates, forms a complete waste, in which
a small cactus is scarcely able to grow. The cause of its sterility
may be the want of rain ; but if it were moist, and obtained
abundant supplies of rain, the nitrates would have disappeared
long since ; and, even without their presence, vegetation would
flourish luxuriantly in this climate.

The common error is to confound a soil, in which nitrates
EXIST, with one in which they are in the act of forming. If the
first soil be Wanting in the conditions (animal matter) necessary
for a further formation of nitric acid, it will prove sterile, but
will, on the contrary, be fertile if these conditions exist. The
latter, and not the nitrates, are therefore the causes of the better
growth of vegetation.

It follows from the preceding observations, that, as far as our
experiments extend, the formation of nitric acid on the surface of
the earth, is dependent on the presence of animal matter.

But as animal substances receive their nitrogen from the
atmosphere in the form of ammonia, the primary origin of the
nitric acid of nitrates must be the ammonia of the atmosphere.
But it may be affirmed, in addition to this, that ammonia is not
the only ultimate source of, but that it is actually the immediate
source of nitric acid. We have reason to believe that the nitro-
gen of decaying animal substances assumes the form of ammonia,
before being converted into nitric acid ; and that it must first be
in the state of ammonia, before it is able to form nitric acid with
the oxygen of the air.* Hence we must view ammonia as the
principal source of the formation of nitric acid on the surface of

• See the Chapter on Eremacansi? in s*>-nnd part of this book.

n

318 • IS NITRIC ACID FOOD FOR PLANTS ?

the earth ; and we may expect the production of the latter
wherever ammonia, and the conditions for its oxidation, are
found united.

The occurrence of large beds of nitrates in America cannot
afford the most distant reason for the assumption that they are
formed in an unusual way ; it is unnecessary to call in the as-
sistance of the nitrogen of the air, in order to explain their great
extent. We find in nature whole mountains consisting of shell-
fish, and of remains of microscopical animals, which must have
contained a certain quantity of nitrogen when alive. We find
also large layers of animal excrements (Coprolites), which place
beyond all doubt the former existence of innumerable individuals
of species now extinct. In the processes of decay and putrefac-
tion to which they have been subjected, the nitrogen of their
bodies could have escaped only in two forms ; in cold climates,
it would assume the form of ammonia, and in warmer countries,
the form of nitric acid, which must accumulate wherever the
salts formed by means of it are not carried off by water.

Ammonia, however, is not the only source of the formation of
nitric acid. In the action exerted by the electric spark on the
constituents of air (which are also the constituents of nitric acid),
we recognise a second source, which, to all appearance, is very
extended.

Cavendish was the first to observe, that by a continued passage
of electric sparks through moist air, its volume diminished, and
an acid, soluble in water, was formed at the same time. This
great philosopher proved, by a series of decisive experiments,
that the constituents of the air, the nitrogen and oxygen, united
to form nitric acid when exposed to the influence of electricity.

Now it is probaole 'that lightning (the most powerful electric
spark known), in its passage through moist air, may effect a com-
bination of the constituents of air, in consequence of which nitric
acid would be formed.

In an examination of rain-water, which the author of the
present work undertook in the years 1826-1827 (Annales de
Chimie et de Physique, xxxv., 329), it was actually found that
out of seventy-seven analyses made of the residue of rain-water,
seventeen of them, obtained by the evaporation of the rain of

FORMATION OF NITRIC ACID. 219

thunder-storms, contained more or less nitric acid, partly in com-
bination with lime, and partly with ammonia. In the sixty others,
only two contained traces of nitric acid.

The occurrence of nitric acid in rain-water as nitrate of
ammonia, renders it uncertain whether the nitrogen of the former
was obtained from the atmospheric air itself, or from the ammonia
existing in it, in the state of a gas. Henry observed that ammo-
niacal gas, mixed with oxygen, and exposed to electric sparks, is
likewise converted into nitric acid. It is obvious, that, if the
rain contains carbonate of lime mechanically mixed with it in the
form of dust, the nitrate of ammonia also present will be con-
verted during evaporation into carbonate of ammonia, which will
escape, and into nitrate of lime, which remains in the residue.
The quantity of nitric acid contained in the rain of a thunder-
storm cannot be estimated. Two or three hundred pounds of
filtered rain-water yield only a few grains of a colored residue,
and the nitrates contained in the latter form only a fractional
part of its weight.

The analysis of the water of springs and of rivers is much
better adapted to give us a clear conception of the quantity of
nitric acid formed by the influence of electricity in the atmo-
sphere. If we suppose the nitric acid to exist in water in a free
state, as it is a volatile acid, it must escape during the evapora-
tion of the water in porcelain vessels, so that the residue will not
contain a trace of it, if the bases necessary for its fixation be
deficient. The water of our springs, streams, and rivers, is rain-
water, which, if nitric acid were originally present in it, must
now contain nitrates, by filtering through the earth, which in-
variably contains lime and alkaline bases.

It follows, from the interesting observations made by Gobel, in
his journey to Southern Russia, that, by the evaporation of the
river Charysacha, which falls into the lake Elton, the latter must
receive annually 47,777 millions of pounds of salts. The water
of the Charysacha contains scarcely 5 per cent, of salts ; so some
conception may be formed of the quantity of water which must
evaporate, in order to furnish the above quantity. The river has
its source about forty wersts from Lake Elton, and obtains its
water from the rain and snow falUng on the mountains.

two IS NITRIC ACID FOOD FOR PLANTS ?

If nitric acid be a constant and generally appreciable consti-
tuent of rain-water, it is obvious that we ought to find sensible
traces of it in the mother liquor remaining behind after the crys-
tallization of the salt. But Gobel did not observe the presence
of nitrates either in the water of the river or in the deposited
salt.

In the water of the Artesian Well* of Grenelle ; in the water
of the Nile ;t in that of the Seine, which contains carbonate of
ammonia in dry seasons ; in the waters of the Thames, or of the
Rhine, no one has yet proved the presence of nitrates.

We may assume, from these facts, that the nitric acid fur-
nished to the earth in Europe, by means of rain, is extremely
small in amount ; so that, even if the nitric acid formed by light-
ning exercise a favorable action on vegetation, still this influence
cannot be considered as a source of the nitrogen of plants. When
it is considered that the number of thunder-storms in a year does
not amount in some districts to above twelve on an average, and
in many to only eight, it must be obvious from this, that it would
be quite impossible to prove the presence of nitric acid in the
waters of rivers or of springs.

Under the tropics, where thunder-storms are much more fre-
quent than with us, we might suppose that the quantity of nitric

* Payen found in 10,000 parts of this water : —

Carbonate of lime - . - . 6*80

" magnesia - - - - 1*42

" potash - - - - 2-96

Sulphate of potash - - - - 120

Chloride of potassium - - - - 1 09

t Regr|i It found in 22 lbs. of water of the Nile : —

Carbonate of lime - - - - 5*30

" magnesia - - - - 7*43

Peroxide of iron ----- 053

Chloride of sodium - - - - 4'77

Sulphate of magnesia - - - - 0-53

Silica 1-06

Alumina - - - - - - 1'59

Extractive matter - - - - 0-53

Carbonic acid 1219

33-93 Grammes ''

DOES NOT YIELD NITROGEN TO PLANTS. 221

acid in rain-water would be appreciably greater. But the known
examinations of the spring and river waters of those regions ;
for example, of the waters of Paipa, near Tunga, of the water of
the Rio Vinagre. and of the hot mineral springs of the Cordilleras,
the analyses of which were instituted by Boussingault, in South
America, without the presence of nitrates being detected, show
that there is no foundation for the opinion that a sensibly greater
quantity of nitric acid is generated in those regions, by the action
of lightning, than in the temperate zones.

It follows, from the preceding observations, that nitric acid, or
its salts, are not destined by nature to yield nitrogen to plants.
If it were actually the case that nitric acid did yield to plants
their nitrogen, we must assume that this source was accessible to
all plants without distinction. But it is completely excluded
from marine plants ; and even in the case of the terrestrial plants
of the temperate and cold zones, the rare occurrence of thunder-
storms would prevent us from considering that any appreciable
quantity of their nitrogen could arise from nitric acid generated
by the action of lightning on the constituents of air.

But^ even on the assumption that nitric acid does take a de-
cided part in vegetable life, ammonia still remains as the ultioiate
source of the nitrogen of plants ; for, as far as oar knowledge
at present extends, all the nitric acid on the surface of the earth
is formed by the eremacausis of ammonia, and it is not impro-
bable that the nitric acid, which occurs in the rain of thunder-
storms, may be dependent on the presence of the same body.

Although we thus trace back the action of all animal and
other substances containing nitrogen, to the only compound which
furnishes this element to all plants, in a state of nature, we do
not of course mean to exclude the application of these other
matters to the purposes of agriculture. When we know that
woollen rags, horn, and hair, in the progress of decay, offer a
slow but continued supply of ammonia, it follows, that we may
use them wherever their price, in comparison with the advantage
anticipated, does not exclude their application.

The same reasoning holds good in the case of nitrates. In
these, nitrogen exists in another form than that of ammonia.
Nitric acid, or rather nitrous acid, is, in its chemical relations,

222 IS NITRIC ACID FOOD FOR PLANTS ?

exactly opposed to ammonia ; but we see, that in the organism
of plants, carbonic acid and water suffer decomposition, although
their constituents are united by a much greater power. We
have considered sulphuric acid as a source of sulphur. Why,
then, should not nitric acid suffer a similar decomposition by the
same causes ; why should not its nitrogen, like the carbon or
sulphur, become a component part of a plant ?

By strewing nitrate of soda over fields, a greater crop has been
obtained, particularly on grass land. Upon corn-fields and on
roots, it has had less influence.

It is not yet decided to what constituent of the salt its favorable
influence is due.

When the crops of hay and straw obtained with this manure
by Mr. Gray, of Dilston, and Mr. Hyett (Journal of the Royal
Agricultural Society), are expressed with regard to their quantity
of nitrogen, the singular result is obtained, that the amount of
nitrogen in these crops amounts to double the quantity of that
contained in the nitrate used as manure !

Now, when it is remembered that the crop of many meadows
is rendered a half, twice, or even three times greater, by ma-
nuring with burnt bones or with wood ashes — with matters,
therefore, containing no nitrogen, it still remains doubtful
whether the action of nitrate of soda should be ascribed to its
nitric acid.

A number of plants, such as Borago officinalis, Mesembryan-
themum crystallinum, Apium graveolens, the sun-flower, and to-
bacco, contain dissolved in their juices considerable quantities of
nitre, which does not exist in other plants growing on the same
soil. The presence of a nitrate in plants permits only one con-
clusion— that the nitrogen of nitric acid is not employed in their
organism for the formation of compounds containing that element,
because, if it were, at a certain period of the life of the plant, it
would disappear on account of this conversion.

Whatever be the case in this respect, nitrates are manures,
which do not replace those constituents of the soil which are re-
moved in the crops. Hence, although either by means of their
acid, or of their alkalies, the rowth of plants may be increased
tor one or two years, this very increase must cause an earlier

NITROGEN OF ThE AIR IN VEGETATION. 225r

period of exhaustion and poverty to the soil. A proper and
lasting advantage cannot he expected from the use of nitrates.

DOES THE NITROGEN OF THE AIR TAKE PART IN VE-
GETATION ?

Priestley and Ingenhouss assumed that plants possess the
power of assimilating the nitrogen of the air. The former states
that a specimen of EpiloUum hirsutum kept under a glass globe
of ten inches in height, and of one inch in width, absorbed within
a month f of the air contained in it.

These experiments have been repeated by Saussure with every
care (Recherches, p. 189), both in pure nitrogen and in atmo-
spheric air, exactly according to the method described by Priest-
ley, but the results were quite the reverse. Saussure observes,
" I have continued the experiments for a long time, but I never
could detect a diminution of the nitrogen. The same was the
case with all kinds of plants which I submitted to the same expe-
riment. Plants, therefore, do not sensibly diminish the bulk of
the air ; and these experiments are confirmed by those of Wood-
house and Sennebier."

Hence, we have not any direct proof for the opinion, that the
nitrogen of the air is converted into a component part of a plant
by its vital processes. In the present state of our knowledge,
indirect proofs are equally wanting.

Many writers on agriculture cite, as decisive proofs of the
assimilation of the nitrogen of the air by plants, the experiments
of Boussingault, but their interpretation in favor of this view is
not supported by facts. This distinguished philosopher instituted
a number of experiments in order to decide the question regard-
ing the origin of nitrogen in plants, and we give the results of
these experiments in his own words (Ann. de Chimie et de Phy-
sique, LXix.) : —

" I believe that I have proved by numerous experiments, that
the nitrogen of a rotation of plants is greater and often much

224 NITROGEN OF THE AIR IN VEGETATION.

greater than the quantity contained in the manure. This excels
arises doubtless from the air, and it is more than probable that,
in this case, a part of the excess of nitrogen is taken up in the
form of nitrate of ammonia, which M. Liebig has shown to exist
as a frequent constituent of the rain of thunder-storms. But
before this can be assumed, it will be necessary to examine the
action of this salt on vegetation.''

In a later treatise on this subject, Boussingault says (Annales
de Chimie et de Physique, 3 Serie, t. i., p. 240) :—

" When these tables are examined, it follows that the nitrogen
in the plants obtained amounts to more than that present in the
manure. I assume, as a general proposition, that this excessi
arises from the air. But in what way and manne" '"^iis ele-
ment IS TAKEN UP BY PLANTS, I AM UNABLE TO STATE. Thc^

nitrogen may be taken up directly as a gas, or dissolved in water,
or, what is possible, and as some philosophers (Saussure for ex-
ample) believe, the air may contain an infinitely small quantity
of ammonia."

The experiments of Boussingault are, therefore, proofs that
the nitrogen of cultivated plants is not obtained from manure
alone, but that, besides this, they contain an excess which can
only be derived from the atmosphere. That the nitrogen of wiid
plants must be derived from the air is so obvious, that it requires
neither proof nor experiments.

Boussingault had not the slightest intention of making his ex-
periments the foundation for the opinion that the nitrogen of air
'might be converted into parts of the plant, but only employed
them as proofs that the nitrogen of cultivated plants is derived
from the atmosphere.

GIANT SEA- WEED. 2tl

GIANT SEA. WEED.

(From Darwin's Journal of the Voyage of the Beagle, pp. 303, 304.)

" There is one marine production, which from its importance is
worthy of a particular history. It is the kelp or Fucus giganteus
of Solander. This plant grows on every rock from low.water
mark to a great depth, both on the outer coast and within the
channels. I believe, during the voyage of the Adventure and
the Beagle, not one rock near the surface was discovered, which
was not buoyed by this floating weed. The good service it thus
affords to vessels navigating near the stormy land is evident, and
it certainly has saved many a one from being wrecked. I
know few things more surprising than to see this plant growing
and flourishing amidst (..ose great breakers of the Western
Ocean, which no mass of rock, let it be ever so hard, can long
resist. The stem is round, slimy, and smooth, and seldom has a
diameter of so much as an inch. A few taken together are
sufliciently strong to support the weight of the large loose
stones to which, in the inland channels, they grow attached ;
and some of these stones are so heavy, that, when drawn to the
surface, they can scarcely be lifted into a boat by one person.

" Captain Cook, in his second voyage, says, that at Kerguelen
Land, ' some of this weed is of a most enormous length, though
the stem is not much thicker than a man's thumb. I have
mentioned, that upon some of the shoals on which it grows, we
did not strike ground with a line of twenty-four fathoms. The
depth of water, therefore, must have been greater. And as
this weed does not grow in a perpendicular direction, but
makes a very acute angle with the bottom, and much of it
afterwards spreads many fathoms on the surface of the sea, I am
well warranted to say that some of it grows to the length of
sixty fathoms and upwards.' Certainly, at the Falkland Islands,
and about Terra del Fuego, extensive beds frequently spring up
from ten and fifteen fathom water. I do not suppose the stem
of any other plant attains so great a length as 360 feet, as suted
11*

22(5 GIANT SEA- WEED.

by Captain Cook. The geographical range is very consider.
able ; it is found from the extreme southern islets near Cape
Horn, as far north, on the eastern coast (according to informa-
tion given me by Mr. Stokes) as lat. 43° — and on the western it
was tolerably abundant, but far from luxuriant, at Chiloe, in
lat. 42°. It may possibly extend a little further northward, but
is soon succeeded by different species. We thus have a range
of 15° in latitude ; and as Cook, who must have been well ac-
quainted with the species, found it at Kerguelen Land, no less
than 140° in longitude.

" The number of living creatures, of all orders,* whose
existence intimately depends on that of the kelp, is wonderful.
A great volume might be written, describing the inhabitants of
one of these beds of sea-weeds. Almost every leaf, excepting
those that float on the surface, is so thickly incrusted with coral-
lines as to be of a white color. We find exquisitely delicate
structures, some inhabited by simple hydro-like polypi, others by
more organized kinds, and beautiful compound Ascidiae. On the
flat surfaces of the leaves, various patelliform shells, Trochi, un-
covered molluscs, and some bivalves are attached. Innumerable
Crustacea frequent every part of the plant. On shaking the
great entangled roots, a pile of small fish, shells, cuttle-fish,
crabs of all orders, sea-eggs, star-fish, beautiful Holuthurise
(some taking the external form of the nudi-branch molluscs),
Planariae, and crawling nereidous animals, of a multitude of
forms, all fall out together.

" I can only compare these great aquatic forests of the
southern atmosphere with the terrestrial ones in the inter-
tropical regions. Yet, if the latter should be destroyed in any
country, I do not believe nearly so many species of animals
would perish, as, under similar circumstances, would happen
with the kelp. Amidst the leaves of this plant, numerous
species of fish live, which nowhere else would find food or
shelter ; with their destruction, the many cormorants, divers,
and other fishing birds, the otters, seals, and porpoises, would
soon perish also ; and lastly the Fuegian savage, the miserable
lord of this miserable land, would redouble his cannibal feast,
decrease in numbers, and perhaps cease to exist."

APPENDIX,

EXPERIMENTS OF WIEGMANN AND POLSTORF

The composition of the artificial soil used in the

experiments of Wieg

mann and Polstorf, on the organic ingredients of Plants, was as follows

(Preischrift, p. 9) :—

Qu>:-zy smd

861-26

Sulphate of potash

0-34

Chloride of sodium ....

0 13

Gypsum (anhydrous)

1-25

Chalk (elutriated) ....

. 1000

Carbonate of magnesia .

500

Peroxide of manganese

2-50

Peroxide of iron ....

1000

Hydrated alumina ....

. 1500

Phosphate of lime ....

1560

^ Acid of peat with potash* .

3-41

" " soda ....

2-22

" " ammonia

. 10-29

lime

3-07

" *• magnesia

1-97

" " peroxide of iron

3-32

alumina

4-64

Insoluble acid of peat ....

5000

* This salt was made by boiling common peat with weak potash ley, and
precipitating, by means of sulphuric acid, the dark-colored solution. This
precipitate is that termed Torfsaeure (acid of peat), in the above analysis.
The salts of this acid, referred to in the analysis, were obtained by dissolv-
ing this acid in potash, soda, or ammonia, and by evapoiating the solutions;
the salts of magnesia, lime, peroxide of iron, and alumina, were obtained
by saturating this solution with their respective bases, by which means
double decomposition was effected. Humus is the substance remaining by
the decay of animal and of vegetable matters, which are seldom absent from
a soil. This was replaced by the acid of peat in the experiments of Wieg-
mann and Polstorf, When the acid of peat is boiled for some time with
water, it passes into an insoluble modification denoted above as insoluble
acid of peat.

22S APPENDIX.

The following experiments were instituted in pure sand, and in the
artificial soil : —

VICIA SATIVA.
A. — In Pure Sand.

The vetches attained by the 4th of July a height of ten inches, and
seemed disposed to put out blossoms. On the 6th of the same month,
the blossoms unfolded ; and on the 11th they formed small pods, which,
however, did not contain seeds, and withered away by the 16th. Simi-
lar plants, which had already begun to have yellow leaves below, were
drawn with their roots out of the sand, the roots washed with distilled
water, and then dried and incinerated.

B. — In Ariijicial Soil.
The plants reached the height of eighteen inches by the middle of
June, so that it became necessary to support them wiih sticks ; they
blossomed luxuriantly on the 16th of June ; and about the 26th put out,
many healthy pods, which contained on the 8th of August ripe seeds,
capable of germinating. Similar plants to the above were taken with
their roots from the soil ; they were then washed and incinerated.

HORDEUM VULGARE.
A. — Iji Pure Sand.
The barley reached on the 25th of June, when it blossomed imperfectly,
a height of li foot, but it did not produce seed ; and, in the month oi
July, the points of the leaves became yellow ; on which account, on the
1st of August, we removed the plants from the soil, and treated them as
before.

13. — In Artificial Soil.

The barley, by the 25th of June, had reached a height of 2J feet, by
which time it had blossomed perfectly; and yielded, on the 10th of
August, ripe and perfect seeds ; upon which the plants, together with
their roots, were taken from the soil, and treated as formerly.

AVENA SATIVA.
A. — In Pure Sarul.
The oats, on the 30th of June, were \h foot in height, but had blos-
somed very imperfectly ; they did not produce fruit ; and, in the course
of July, the points of their leaves became yellow, as in the case of the
barley ; on which account the stalks were removed from the soil on tlie
l6t of August, and treated as formerly.

B. — In Artificial Soil.
The oats reached 2^ feet on the 28th of June, having blossomed per-

APPENDIX. 22d

fectly. By the 16th of August they nad produced ripe and perfect
seeds ; the stalks and roots were, therefore, removed from the soil, and
treated as above.

POLYGONUM FAGOPYRUM.
A. — In Pure Sand.
The buck-wheat, on the 8th of May, seemed to flourish the best of all
the plants grown on pure sand. By the end of June, it had reached a
height of 1 i foot, and branched out considerably. On the 28th of June,
it began to blossom, and continued to blossom till September, without
producing seeds. It would certainly have continued to blossom still
longer, had we not removed it from the soil on the 4th of September, as
it lost too many leaves : it was treated as before.

B. — In Artificial Soil.
The buck-wheat grew very qiiickly in this soil, and reached a height
of 2i feet. It branched out so strongly, that it was necessary to support
it with a stick; it began to blossom on the 15th of June, and produced
perfect seeds, the greater number of which were ripe on the 12th of
August. On the 4th of September, it was taken from the soil along
with the roots, and treated as before, on account of losing too many
leaves from below ; although it was partly still in blossom, and with
unripe fruit.

NICOTIANA TABACUM.
A. — In Pnre Sand.
The tobacco-plant sown on the 10th of May did not appear till the 2d
of June, although it then grew in the normal manner ; when the plants
had obtained their second pair of leaves I removed the superfluous
plants, leaving only the five strongest specimens. These continued to
grow very slowly till the occurrence of frost in October, and obtained
only a height of five inches, without forming a stem. They were
removed along with their roots from the sand on the 21st October, and
treated as the above.

B. — In Artificial Soil.
Th^ tobacco sown on the 10th of May came up on the 22d of the
same month, and grew luxuriantly. When the plants obtained the
second pair of leaves, I withdrew the superfluous plants, and allowed
only the three strongest to remain. These obtained stems of above
three feet in height, with many leaves ; on the 25th of July they began
to blossom ; on the lOlh of August, they put forth seeds ; and, on tht

230

APPENDIX.

8th of September, ripe seed capsules, with completely ripe seeds, were
obtained. On the 27th of October, the plants were removed from the
soil, and treated as above.

TRIFOLIUM PRATENSE.
A. — In Pure Sand.
The clover, which appeared on the 5th of May, grew at first pretty
luxuriantly, but reached a height of only 3i inches by the I6th of Octo-
ber, when its leaves became suddenly brown, in consequence of which I
removed it from the soil, and treated it as above.

B. — In Artificial Soil.
The clover reached a height of ten inches by the 16th of October ; it
was bushy, and its color was dark green. It was taken from the soil, in
order to compare it with the former experiments, and was treated in the
same way.

CONSTITUKNTS OF THE ASHES OF THE SEED.

100 parts of dry seeds yield —

Soluble in Soluble in
water. muriatic acid.
Viciafaba. . . . l-,502 0563
Hordeum vulgare . . 0-746 0-563
Avena sativa . . . 0 465 0 277
Polygonum fagopyrum . 0823 0*547
Trifolium pratense . . 1-218 3-187

Silica.
0-442
1423
2122
0-152
0-2S2

Ashes in
100 pirts.
= 2-567
= 2 432
= 2-864
= 1-5-22
= 4-687

CONSTITUENTS (

OF THE ASHES OF THE

PLANTS GROWN IN PURE SAND

AND IN THE ARTIFICIAL SOIL.

Soluble in
water.

Soluble in
muriatic acid

Insoluble in water
and muriatic acid

'.Silica). Ashes

Vicia sativa, J
15 grms. plants, )
dried in air . . j

' In sand . . 0-516
j In artificial soil 0-693

0 375
0-821

0-135
0-3-20

= 10'26
= 1-834

Hordeum vul- 1
gare, 125 grms.
plants ...

Avena sativa,
13 grms. plants,

Polygonum
fagopyrum .

^Sand . . 01-23
[Soil . . 0-167

0-195
0-2-26

0-355
0-487

= 0-673
= 0 880

iSand . . 0 216
' Soil . . 0-225

0-0-24
0-030

0-094
0-226

0-354
0-461

0-045
0-133

= 0-594
= 0-746

= 0-225
= 0-507

Nicotiana
tabacum ..."

'Sand(4grms. K.200
plants) . .^223

1 Soil 12-5 I g
^plants) . .5^^*^

*Sand . . . 0-522
|Soil . • .0 659

0-252
2-228

0031
0-549

= 0-506
= 3-923

Trifolium "
pratense, 145
grammes plants '

0350
0-943

0-091
0-082

= 0-96S
« 1-684

APPENDIX.

331

The preceding numbers express the unequal weight of mineral nutritive
substances taken up from the sand and artificial soil by equal weights
of the different plants mentioned. The absolute and not the relative
weight of the component parts of the ashes is given. For example, the
live tobacco plants grown in sand gave 0*606 gr. in ashes, whilst the
three which grew in the artificial soil gave 3*923 ; five would, therefore^
have given 6*525 gr. The proportion of the mineral ingredients taken
up by five tobacco plants from the sand, and that taken up from the arti-
ficial soil by an equal number of plants, is as 10: 120. In an equal
space of time, those whicii grew in the artificial soil absorbed nearly
thirteen times more of inorganic ingredients than those in the sand, and
the whole development of the plant was exactly in proportion to the
supply of food. Wiegmann and Polstorf subtracted the ashes of the
seed used from the numbers in the last line, which show the amount of
ashes in a given weight of the grown plant^; but this has caused a small
error in the numbers, as all the plants grown in the sand were reduced
to ashes, and a corresponding amount only of those grown in the arti'
ficial soil. The v/eight of the seed of every plant grown was 3 grammes
if we except the tobacco, which was not weighed.

TABLE

Showing the Amount of Moisture in the Vegetable Substances analysed
in the Experiments of Boussingault.

—

Subst. dried
at 110" C.

Water.

Subst. dried
at llO'' C

Water.

Wheat. . . .

Rye

Oats . . . .
Wheat straw .
Rye straw . .
Odt suaw . .
Poutoes . . .

0-855
0-834
0-792
0-740
0-813
0713
0-341

i
6666666,

Beet

Tnrnips ....
Helianthus tub. .
Pcis ...
Pea straw .
Clover st'ilk . .
SUilkofHel.tub.

0-122
0-075
0-208
0-914
0-882
0-790
0-871

0-878
0-925
0-792
0-086
0118
0-210
0-129

COMPOSITION OF MANURE DRIED IN VACUO AT 110" C

Carbon.

Hydrogen.

Oxygen.

Nitrogen.

Salts & Earths.

I.

II.
III.
IV.

V.
VI.

Mean.

324
325

38-7
36-4
40-0
345

358

3-8
4-1
45
40
43
43

4-2

25-8
26-0

28-7
191
27-6

27-7

25-8

1-7
1-7
1-7
2-4
2-4
2-0

2-0

363
357
26-4
38-1
25-7
315

232

APPENDIX.

These results show that the quantity of this manure necessary for one
hectare of land (4 Hessian acres) during five years contains ; —

Carbon

Hydrogen

Oxygen

Nitrogen

Salts and earths

Kilogrammes.

3637-6

426-8

25-21-5

203-2

3271-9

COMPOSITION OF THE PRODUCE OF THE LAND DRIED IN
VACUO AT 110^ C.

With the Ashes.

Without the Ashes. (

1

1

1

1

1

0)

1

e

i

g

O

^

o

55

<

O

»

o

iS

Wheat ...

461

5-8

434

23

2-4

472

6-0

44-4

2-4

Rye ....

46-2

56

442

17

23

473

57

453

1-7

OiiLs ....

50-7

6-4

36-7

2-2

4-0

52-9

66

38-2

23

Wheat straw .

48-4

53

38-9

0-4

7-0

52 1

57

41-8

0-4

Rye straw . .

49-9

56

40-6

0-3

36

51-8

5-8

42-1

0-3

Gilt straw . ,

5ifl

5-4

39-0

0-4

51

52-8

57

411

0-4

Potatoes . . .

44-0

5-8

44-7

1-5

4-0

45-9

61

46-4

16

Beet ....

42-8

5-8

434

17

63

457

6-2

46-3

1-8

Turnips . . .

429

55

423

1-7

7-6

46-3

6-0

45-9

1-8

Helianthus tub.

433

5-8

433

1-6

60

460

6-2

461

1-7

Yellow peas .

465

6-2

40-0

42

31

480

6-4

413

43

Pea straw . .

45-8

50

3.5-6

23

113

51-5

5-6

403

2-6

Red clover hay

47-4

50

37-8

21

7-7

513

54

411

2-2

Stalk of Hel. tub

457

54

45-7

0-4

2-8

470

5-6

470

04

1. ROTATION.

Year.

Substances.

Produce

of a
Hectare.

Dry
Produce

Carbon.

Hydrog. Oxygen.

SalU
Nitrog.! and
Earths.

2

3

4

5
Mant

Potatoes . .
Wheat. . .
Wheat straw
Clover (hay)
Wheat . . .
Wheat straw
Turnips . .
Oats . . .
Oat straw

Total . .
re used . . .

Kilogr.
12800
1343
3052
5100
1659
3770
9.'>50
1344
1800

Kilopr.
3085
1148
2258
4029
1418
2790
716
1064
1283

Kilogr.

1357-4
5293

10930

1909-7
653-8

13.504
307-2
539-5
642-8

Kilogr.

178 »
66-t,

119-7

301-5
82-2

147-8
393
68-0
693

Kilogr.

1379.0
4982
878-2

15230
6154

1085-3
302-9
390-5
500-4

Kilogr. Kilogr.
46-3 1234
264 27-5
9-0 ; 158-1
84-6 ^ 3102
32-6 340
11-2 19.5-3
12-2 54-4
23-3 42-6
51 65 4

40418
49086

17791
10161

83831
3637-6

973-3 1 7172-9
4268 2621-5

250-7 1010-9
303-2 3271^9

Differ

ence ....

+7630

+47455

+546 5 1 +4551-4

+47-5 — 2261-0 i

APPENDIX.

5:^3

2. ROTATION.

Produce

Dry

Salts

Year.

Substances.

of a
Hectare.

Produce

Carbon.

Hydrog.

Oxygen.

Nitrog.

and

Earths.

Kilogr.

Kilogr.

Kilogr.

Kilogr.

Kilogr.

Kilogr. i Kilogr. |

1

Beet. . . .

26000

3172

1357-7

1840

1376 7

539

199-8

2

Wheat. . .

1185

1013

4670

58-8

439-0

233

243

Wheat straw

2693

1993

964-0

105-6

775-3

8-0

1395

3

Clover . . .

5100

4029

1909-7

2015

15230

84-6

3102

4

Wheat. . .

1659

1418

653-8

82-2

615-4

326

34-0

Wheat straw

3770

2790

1350-4

147-8

1085-3

11-2

195-3

Turnips . .

9550

716

307-2

393

302-9

122

54-4

5

Oiits . . ,

1344

1064

539-5

68-0

390-5

23 3

426

Oat straw .
Total . .

1800

1283

642-8

693

500-4

51

654

53101

17478

8192-1

956-5

7009-1

2542

1005-5

Manure used . . .

49086

10161

3637-6

4268

26215

2032

3271-9
—22064

Diffen

3nce ....

+7317

+45545

+529-7

+4387-6

+51-0

3. ROTATION.

Produce

Dry

Salts

Year.

Substances.

of a
Hectare.

Produce.

Carbon.

Hydrog.

Oxygen.

Nitrog.

and
Earths.

Kilogr.

Kilogr.

Kilogr.

Kilopr.

Kilogr.

Kilogr.

Kilogr.

1

Potatoes .

12800

3085

1357-4

178-9

13790

46-3

123-4

2

Wheat . .

1343

1148

529-3

66-6

498-2

26-4

275

Wh't straw

3052

2-258

1093-0

119-7

878-2

9-0

158-1

3

Clover stiilk

5100

4029

19097

201-5

15220

84-6

310-2

4

Wheat . .

1059

1418

653-8

82-2

615-4

32-6

34-0

Wh't straw

3770

2790

1.350-4

147-8

1085-3

11-2

1953

Turnips .

9550

716

307-2

39-3

30-2-9

122

544

5

Peas. . .

1092

998

464-1

61-9

399-2

419

30-9

Pea sUaw .

2790

2461

11273

1230

8761

5(i-6

2781

6

Rye . . .

1679

1394

644-0

78-1

616-1

237

.^2-1

Rye straw
Total .

3731

3033

1513-5

169-8

1231-4

9-1

109-2

46566

23330

10949-7

1268-8

9404-8

3536

1,353-2

Manure used . .

58900

12192

43<)4-2

5122

3145-5

243-8

3925-8

Differ

ence . . .

+11138

+05855

+756-6

+62593

+109-8

—2572-6

4. ROTATION.

Year.

Substances.

Produce

of a
Hectare.

Dry
Produce

Carbon.

Hydrog. Oxygen.

j

Nitro.

Salts

and

Earths.

1
3&3

Mam

Manured fallow
Wheat . . .
Wheat straw .

Total . .
ire used . . .

Kilogr.

3318
7500

Kilogr.

2836
5550

Kilogr.

1037-4

2686-2

Kilogr.

164-5
294-2

Kilogr.

1230-8
21,59-0

Kilogr

65-2
2-22

Kilogr.

68-1

388-5

10818
20000

8386
4140

3723-6
14821

458-7
173-9

33898
1068-1

87-4
82-8

456.6
13331

Differ

ence

1+4246

+2241-5

+284-8 +2321-7

i

+4-6

-876-5

23«

APPENDIX.

«-•

If

PI

5;== '^

Sc9 »:-

•2 ^

■C is

I I-

<N

I 2

TABLE

Of the Mineral Constituents put on a Hectare of Land, tn the Manure

during five years, in Kilogrammes.

—

Total weight.

of

the ashes.

Phosphoric
Acid.

i

i

•i

1

1.
1-°

P

52

Ashes of the dung . .

Composition of the ix;at

ashes

3272 98
5000 0

62
270

30
15

281
300

118

30

SU 2333
115 3275

3U0

185

Sum

8272 98

332

35

581

148 1 370 j 5508

385

APPENDIX.

235

COMPOSITION OF THE ASHES OF PLANTS GROWN AT
BECHELBRONN.

e a

■ -\
hi

Names of the

i

CB*

^

?l

Plants.

r<

m

08

■S

c

li

O a

o

.

Ph

o

'^

•-J

ft.

(»

'^

! Pofcitoe3 . . .

13-4

71

11-3

2-7

5-4

1-8

51-5

trace

56

0-5

0-7

1 Rod beet . . .

161

1-6

60

52

4-4

7-0

390

60

80

2-5

4-2

j Swedish turnip

140

10-9

61

2-9

43

10.9

33-7

41

6-4

12

5-5

Jerusalem arti-

chokes . . .

110

2-2

108

1-6

1-8

2-3

44-5

trace

130

52

7-6

Wheat griin .

00

10

47-0

trace

15-9

2-9

29-5

trace

1-3

00

24

Wheat straw .

00

10

31

00

5-0

8-5

9-2

03

67-6

10

3-7

0;it prain . .

1-7

10

149

0-5

7-7

3-7

12-9

00

533

1-3

30

Ont straw . .

32

41

30

4-7

2-8

8-3

2-t-5

44

40-0

21

2-9

Clover. . . .

250

2 5

63

2-6

63

24-6

26(>

0-5

53

03

00

Peas ....

0-5

4-7

301

1-1

11-9

101

353

25

1-5

trace

2-3

French beans .

33

1-3

26-8

01

11-5

5-8

491

00

10

trace

11

Common beans

10

1-6

342

0-7

8-6

51

45..

00

0-5

trace

3-1

(Boussingault, Economie Rurale, p. 327.)

TABLE OF THE MINERAL CONSTITUENTS, OR ASHES, GIVEN
TO A FIELD AND REMOVED FROM IT.

ill

— ^ 2

S

•a

Mean produce on one hec-

S-i

V

S

s,-

tire of land= 10,000

■l^

2^

c

?'.

.CS

square metres.

mer
stitu
the

t<=

1

a

.H-

<■

!U

02

O

H^

S

^

in

Isi planting:

Potatoes

123-4

139

8-8

33

22

6-7

63-5

6-9

m

In the 2<l and 4th years :

g

Wheat grain . . .

550

25-8

0-6

0-0

16

8-8

16-2

0-8

E

Wheat straw . . .

390-6

120

40

2-4

33-2

19-6

37-2

264-0

^'^

In the 3d year :

^

Clover

310-2

195

7-7

81

76-3

19-5

84-1

16-4

^

In the 5th year :

O It grain ....

42-6

6-4

0-4

0-2

1-6

3-3

5 5

22-7

Oat straw ....

654

T9

27

30

54

1-8

189

26-2

Turnips (half crop) .

544

33

5-9

1-6

5-9

2-3

20-6

35

1010-9

82-8

30-1

18-6

126-2

62-0

246-0

340-5

Ashes of the manure* .

82720

980

332-0

350

581-0

1480

370-0

55080

Excess above amount >
of ashes in the crop . J

72011

15-2

301-9

10-4

454-8

86-t)

1240

5167-5

(Boussingault, Economie Rurale, p. Si 4, n. 336.)

Consisting of dung and peat -ashes, the ashes of which bore to each other
the relation expressed in the following table.

a36

APPENDIX.

TABLE

Of the Mineral Constituents added to and removed from the Soil in thk
Cultivation of Helianthus tuberosus. {Topinambour.)

is

11

u

s

m

4>

C

1

6

a

13

i

II

i

02

Ashes of the tultt-m raised .
in the 1st and 2d years* '
Ashes of the dung . . .
Peat ashes

Sum of the ashes of the
manure

Excess

6600

30290
5000-0

712
910
0

146

57-6
2700

10-6

18-2
150

15-2

2605
3000

11-8 293-6
1090 236-2
30-0 ! 115-0

85-8

20110
32750

80290

910

3270

332

1 1
560-5 11390 1351-3

5286-0

73690

198

3130

226

5453

127-2

577

52000

(Boussingault, Economic Rurale, p. 336.)

* The woody and other parts of the plant were burned on the -spot, and
thus left to the soil.

Hat/ grown in Meadows, watered by the Sauer, near Biirrenbach, in tw»
crops (1841 to 1842) yielded 6 to 6'2 per cent, of ashes of the following
composition : —

I.

II.

III.

Average.

Cirbonic acid

Phos|)horic acid ....

Sulphuric acid

Chlorine

Lime

Miignesia

90
53
24
23

20-4
60

161
1-2

337

55
53

2-9
2-8

15-4
8-3

273
2-3

29-2
0-6
0-4

5-5

=

0-5

—

7-3
54

2-7
2-6

17-9
7-2

21-7
1-8

31-5
0-9
10

Soda

Silica

Oxide of Iron • . . .
IiOSS

100

100

100

100

APPENDIX.

237

\f the annual produce of hay he estimated on the average at 400 kilo-
grammes per hectare, then along with it there must be removed in the
crop, from the same surface, 244 kilogrammes of ashes, consisting of ■

Kilogrammes.
Carbonic acid . . . . 178

Phosphoric acid . . . 13*2

Sulphuric acid . . . .66

Chlorine .... 6-3

Lime ..... 43"7

Magnesia .... 17*6

Potash and Soda .... 57-3
Silica ..... 76-9

Oxide of iron . . . .4*6

2440

(Boussingault, Economie Rurale, pp. 339 — 340.)

COMPOSITION OF A STABLE MANURE.

ACCORDING TO THE ANALYSIS OF RICHARDSOIir

The fresh Manure contained :

. 64-96

Water

Organic matters

Ashes . . . . .

24-71

10-33

100-00

The Manure dried at 212* contained :—

Carbon . . . . .

37 40

Hydrogen ....

5-27

Oxygen . . . . .

25-52

Nitrogen ....

1-76

Ashes ...

3005

100-00

The Asnes contained :

I. Soluble in Water:

Potash ....

322

Soda

2-73

Lime ....

0-34

Magnesia ....

0-26

Sulphuric acid .

3-27

Chlorine ....

3-15

Silica .....

0-04

II. Soluble in Hydrochloric acid :

Silica . . . . .

27-01

Phosphate of lime .

7-11

" magnesia .

2-26

*• peroxide of iron

4-68

Carbonate of lime

9-34

" magnesia

1-63

III. Sand (30-99), Charcoal (0-83)

and Loss (3 14) ,

34-96

10000

23S

APPENDIX.

■*^

o
CO "S

90JBJ0J

or o M o »ft
■r ^ »:- C5 t-

M M W f-< C<

•AVBJJg Tiaj

T

•AVBJJS TJOJ

'suBag piaij

JO MT3JJg

•OODEqOJ,

jaAOUB}j

•oosBqoj,

■BUBAKH

■fOAtiaq aui J

•soABa^ Jij[

•j[JBa iU

'POOAV -ti J

-pooMqasag

rH t- CO

T)< >h Tt< o do if-

eo to (N

E ? 5; S 8 S? ^.

-< -H OS -^ o -^ r-

8 ?3 «s p? §8 t^ «

M PJ do (O 00 O

5 8 S S ^

6 «b ■* Ai e»

?§^

SSSS8SI2 i;;

O »h « d< rH i^ M

3; «b « © o o 6*

• ... . -i .

^ I '%^

ill •- -I -.^iall •

.o^o,|o.g^gjSggSgS

B « SO 3 = «! tg ^ ^ JS 43 J3 a

APPENDIX. 239

ANALYSIS OF THE ASHES OF THE STRAW OF RYE, BY
DR. FRESENIUS.

A. — Ingredients soluble in water and muriatic acid.

Potash united to silicic acid * . . . . 6*88

Sulphate of potash . . . . . . 1 -75

Chloride of potassium ..... 0'25

Chloride of sodium . . . . . 0*56

Lime united to silicic acid ..... 4*19

Magnesia . . . , , . . 0*76

Phosphate of lime . . . . . . 2'50

Phosphate of magnesia . . . . . 1-28

Phosphate of oxide of iron . . . . .1*57

Small quantity of phosphate of protox. of manganese. 19*74

B. — Residue insoluble in water and muriatic aetd.

Potash united to silicic acid ..... 9'21

Lime united to silicic acid . . . . 3-43

Magnesia united to silicic acid . . . . . 1'16

Phosphate of iron . . . . . . 1-63

Phosphate of protoxide of manganese .... traces

Silicic acid ....... 63-89

Carbonaceoous matter ..... 0'94

SO-26

10000

Soluble and insoluble together.

Potash united to silicic acid ..... 16'69

Sulphate of potash ...... 1*75

Chloride of potassium ...... 0*25

Chloride of sodium . . . . . . 0 56

Lime united to silicic acid . . . 7'62

Magnesia .... . . 1*92

Phosphate of lime ...... 2'50

Phosphate of magnesia .... . 1-2S

Phosphate of oxide of iron ..... 3-20

Small quantity of phosphate of protoxide of manganese.

Silicic acid . . . . . . 63*89

Carbonaceous matter . . . . . . 0*94

10000

ud

APPENDIX.

•jooH oooaqo^x.

•AlBJig aojBjoj

•aiaj auiqa

•AVBJjg j«aqM

'IBoajBiio au{j

•pooM 'aPlV

•lunJiSTJiibnis

•japia paujaq
-p»a J" [>ooM

•pc)OA\
Xajaqo qaiKqoj^f

•poo^VV siinq

HJBa '^^i^

•pooM 5(Bo

•qaaaa
pan JO iB03JBq3

•qoaag ajiHAV
JO inoaiKqo

•qoaaa
a»RMJopooAV

Ml- O « 8 5J

^ h- oodo Ah

f? O OD (» t- »^ t-

"?" 99

300 o CTOoo y/i iflo

ifl o C5 « » «

db jj «bo

© t- O ff< Ifl !0

©© ©o© © o

©«XX©iflQO

00 »» ^SSxS «

2g g;''--^ S

S "3'

S S

Q<p©(p 00-4^

pj©ioaji>rtPj

^1

■1:=

5 a w * «

:-Sl-2

8^

••5 -2

li

APPENDIX.

241

•pooA\

u? m O O •'5

>A r>o * o c? «
lorj "-< o

S 00 •* i-HQO S I

*pooA\ a^Jl'-wvog

•pooA\ n^MH

VK)
i«lOHJopooA\

sii3i&at)ja pooA\

•pooAV

•5 s «

III

e -s © « ci o »P

on

•-< 1— I l/S tt" O CK'
00 00 O CTr»< I--

»h <j» ih do c< Tj*

O-^f o o

OO OMO C<0

OO

S;:!''^'

-jnuiBAAJopooM

11

•g*^g'

:ei

"-" o e "5 c3 ^ "^ .S * S

x&iOQo6fiLiis3l^d<

ANALYSES OF ASHES BY BERTHIER.

Fern.

Wheat

Straw.

Share

Grass.

Heath.

Rhine
Fern.

Sulphate of potash ....

070

0-4

120

50

33

Chloride of potassium

Uace.

32

114

1-2

9-0

Carbonate of potash

trace.

6-8

16-7

Potash with silica .

130

Silica

730

71-5

.w-a

37-5

16-5

Carbonate of lime

24-8

9-6

(i2

280

434

Sulphate of lime

14-4

Phosphate of lime

10

23

. 2-2

1^0

10^

Magnesia • . .

0.^

30

1-0

OiJ

Oxide of iron . .

1-4

0-7

Oxide of manganese

61

0-2

. 1000

1000

1000

1000

1000

12

•43

APPENDIX.

DE SAUSSURE'S INQUIRIES INTO THE ORIGIN OF THE
MINERAL INGREDIENTS.

Granite frorn
Mount
Breven.

Stone of the
La Salle Mount.

Limestone.

of Reculey de

Thoiry.

Lime

Alumina

Silica

Oxide of iron and manga-
nese

Carbonic acid

Petroleum

Loss

1-74
1325
73-25

2-76

24-36— (Carbonate.)

30-

13-

27-

1-64

9-8
0625

025
0-5

According to De Saussure, the proportion of water, carbon, and ashes
in the plants, of these three mountains is as follows :

100 parts fresh

1

branches with
leaves lost by dry-

And give, of

ing in the air.

Water. \

Carbon.

Ashes.

A.

B. ''

A.

B.

A.

B.

Pine ....

5117

48-24

10-62

11-11

1-187

1-128

L-arch. . . .

5807

5713

10-16

10-39

0-961

0-926

Oleander . .

59-73

52-78

9-05

962

0-654

0-339

Bilberry . . .

50-11

47-60 :

11-69

12-32

1-096

1-048

Juniper . . .

55-19

40-00 1

10-63

11-46

1-081

1-082

100 Ashes contain

Bilberry.

Pine.

a

c

a

b

e

Carbonate of potash • • • i

J 3-60
4-24

7-36 ,

Sulphate of potash . . . . '

). 16-38

23-50 -

12*63 i

► 15

Chloride of potassium . .

•

Carbonate of lime ....

40-35

53-70

46-34

51-19

63

Carbonate of magnesia . .

5-85

6-77

Alumina

17-54

1425

14-o6

11-95

16

Silica

13-45

175

13-49

6-87

Oxide of iron and man- )
ganese J

■

6-43

6-80

10-52

10-00

3

10000

100-00

99-82

100-00

97

APPENDIX.

243

Oleander.

Juniper.

a b c

a c

Carb. sulph. and chloride of pot. .

Carbonate of lime

Carbonate of magnesia

Alumina

Silica

Oxide of iron and manganese . .

10-82
30-02

500
28-80
14-86

8-40

12-25

57-00

13-31
5-44
1100

17-76
71-54

593

4-8G

15-25
64-25

0-53

140
66-6

97-90

9900

10009

100 Parts of the Ashes of the Humus on which those Plants grew, gave—'

Earth of
Pine.

Earth of
Oleander.

Erirlh of
Juniper.

a c

c

c

Salts of potash

Carbonate of lime

Carbonate of magnesia ....

Alumina

Silica

1-16

0-37

14-00

60-50

16-00

4.57
23-20

37-10
1310
1610

1-85
10-65

43-70
14-27
23-83

13-0

Oxide of iron and manganese .

92-03 1 94-68

100-30

244 APPENDIX.

ANALYSES OF THE ASHES OF SOME PLANTS,

BY DE SAUSSURE.
CHEMICAL INQUIRIES INTO VEGETATION. LEIPZIG, 1805.

The method of analysis employed by De Saussure consisted of the
following :

A. The ashes were treated with water, and the parts soluble in it were
introduced into. the calculations, in the second and following columns.

B. The residue remaining undissolved in the last operation was dis-
solved in nitric acid, and evaporated to dryness ; the portion now insolu-
ble in water was silica.

C. By precipitating the solution obtained in B, with prussiate of pot-
ash, the iron and manganese were obtained, the amount of iron supplied
by the re-agent being subtracted in the calculation.

D. By a further precipitation of the solution with ammonia, the earthy
phosphates were obtained (lime and magnesia).

E. By treating this precipitate with caustic potash, neutralizing it
with an acid, and precipitating it with ammonia, the earthy phosphates
mixed with alumina (phosphate) were procured.

F. By a further precipitation of the liquid D with carbonate of soda,
and, by continued boiling, the earthy carbonates were obtained.

G. The difference of the products of these different operations, when
compared with the total weight of the ashes analysed, expressed the few
per cent, loss ; and the quantity of salts with alkaline bases which were
not dissolved by the first treatment with water.

According to the second mode of procedure, which Saussure considers
to be the most exact, the ashes, containing alkaline phosphates, were
chiefly analysed.

The ashes were dissolved in nitric acid, the lime and magnesia sepa-
rated as phosphates, the liquor evaporated to dryness, and heated to red-
ness with the addition of charcoal.

The residual salts were now saturated with acetic acid, dried and
treated with alcohol ; the phosphates and sulphates of potash, and chloride
of potassium, were left behind.

APPENDIX. 245

b. The residue was taken up by water, and mixed with acetate of
.ime ; the residue being dried and heated to redness, was treated with
acetic acid (c), and the portio.i not dissolved was estimated as pure
phosphate of lime, of which it was assumed that 100 parts corresponded
to 129 parts phosphate of potash ; for 8 Ca O + 3 Pa O^ gives 3 (Pj O5,
3K0).

The solutions a and c, and also that remaining after the precipitation
with acetate of lime, were evaporated and heated to redness ; the residue
was weighed, and the chlorine and sulphuric acid estimated, and calcu-
lated as chloride of potassium and sulphate of potash. By subtracting
the two latter salts, and also the potash calculated from the phosphate
of lime, from the weight of the whole residue, the quantity of potash not
existing as phosphate of potash was obtained.

^either of these two methods can be considered accurate in the
present day. But as all the analyses were executed according to similar
methods, the results are always of value, in so far as they are, to a cer-
tain extent, comparable with each other.

246

APPENDIX.

f e

■ ■■ ■

a Fa
raw
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eds.

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6

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c>

ifi

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00

l«

s

d»

o

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^

o

N

>•>

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w

12

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00

1^ £^

CO

o

c»

in

pace

f , s

*(>

s

s

s

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go 3

s

^

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32 g

s i

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kfl

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3

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s?

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do

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IS

g

£o^

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t-

^

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c»

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00

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n)

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^

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t-

^M

sof

ns).

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g

U)

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SI

5?

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^

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s

s?2

ifl

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do

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a:
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=.

S

rt

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J3

1

u

U

m

^

h

APPENDIX.

247

ANALYSES OF THE ASHES OF PLANTS,

BY DE SAUSSURE.

100 Parts Ashes

contain

... 1

Name of Plant.

lit

It

ICO parts of A«he
give Soluble Salts

Us

IP
111

'SI"
IS

£3

II

c

6

1

Oak leaves 10th May

53-

72-24

24-

0-64

012

3-

47-

" 27th Sept

r)5-

425

18-25

1-75

23-

14-5

17-

" peeled branches

4-

58-58

28-25

1-

1225

012

26-

" the bark of above

60-

29-75

4-5

1-75

63-25

0-25

7-

" wood of same .

2-

59-25

4-5

225

32-

2*

386

" sap of same . .

4-

55-3

24-

2-

ir

7-5

32-

" bark of same. .

CO-

28-5

3-

2-

66-

1-5

7-

" inner bark of some

TS-

29-75

3-75

1-

65-

0-5

7-

" e.xtract of the woo(

61-

51-

Oakwood, mould . .

41-

32-5

10-5

14-

10-

32-

Aqueous extract of the
mould

111-

66-

Leaves of the Populus
nigra, 2<Uh May . \

f)6-

51-5

13-

1-25

29-

5-

36-

100 Parts Ashes

contain

'S^

IS

'S

Name of Plant.

kalies an
s with al
ne bases

IS

1.1

11

si -

II

1

^e.

^1

II

6

S4

Leaves of the Poplar]

(Populus nigra) 12th \
Stem of the Poplar . .

93-

44-

'*'

1-5

36-

'•5

26-

8-

50-5

16-75

1-5

27-

3-3

20-

Bark of the same . . .

72-

29-2

5-3

1-5

60-

4-

6-

Leaves of the Hazel- "l

nut (CoryluM ^vel- >

61-

50-7

32-3

1-5

22-

2-5

28-

lima), 1st May . J

Ditto, 22d June . . .

62-

30-

19-5

2-

33-1

4-

22-7

" 20th Sept. . . .

70-

44-

14-

1-5

29-

113

11-

Peeled branches . . .

5-

28-

12-

2-

36-

22-

24-5

Bark of same . . . .

62-

56-7

35-

012

8-

0-25

12-5

348

APPENDIX.

ANALYSES OF THE ASHES OF PLANTS,

B"V DE SAUSSURE.

100 Parts Ashes contain

||

J.

"o .

.2.2

iS

c

-'<

Name of plant.

c^

Si;

■^r^

1-5 £

4; 2

K 3

SS

^ =

^■s

iM

Jw

'£

IS.

<5

25

«

Il

Wood of Moms nigri . .

7

41-38

2-25

0-2

56-

0-12

21-

Soft wood of the same . .

13-

47-5

27-25

02

24-

1

36-

Bark of the same ....

8a-

30-13

8-5

1-1

45-

1525

7-

Inner part of the bark . .

8d-

:34-38

16-5

1-

43-

0-13

10-

Wood of the white beech,

Carpinus betuhis . .

fi-

48-63

23-

225

26-

012

22-

Sap of same

7-

47-

36-

1-

].r

1-

18-

Bark of same

134-

34-88

4-5

012

59-

15

45

Horse chestnut ....

35-

9-5

1

Leaves of same, 10th May

72-

50-

1 Onlj

• those salts which are soluble in 1

From 23d May to 23d July.

84-

24-

f

water were determined.

From 27th September . .

86.

13-5

J

Name of plant.

Is

1-
■c-g

100 Parjs Ashes contain

is

il

2 2

^

rbonates of
Earths.

s

<

<*-

i^

"

IS

Chestnut blossoms . . .71-

50-

Sunflower, before blossom-

ing, 25th June . . . 141-

79 67

6-7

013

11-56

1-5

68-

Ditto, 23d July .... 137-

79-78

6-

0-12

12-

1-5

61-

Ditto, with seed ....

69-25

22-5

0-5

4-

375

52-

Pine leaves from the Jura,

20th June

29-

4013

li27

1-6

43-5

2-4

16-

Ditto, from siliceous land .

39-

34-5

12-

55

29-

19-

15-

Bilberries (chalk soil), 20th

August

26-

36-38

18-

18-

42-

0-5

17

Bilberries (siliceous soils)

••"■

41-5

22-

22-

22-

5-

24

APPENDIX.

249

1

<

Schmidt. l
Bichon.

Thon.

Boussinganlt.

Will and Fresenius.

Bichon.

Schmidt.

Will and Fresenins.

Bichon.

Will and Fresenins.

Boussingault.

Levi.

Letellier.

Hruschauer.

Roleck.

Bichon.

Souchay.

Leuchtweiss.

1^

bc-o K ^ a- tea ft a a e a

1 1 1 1 f 1 i 1 1 1 1 1 1 1 1 1 1 1 1 1 1

•uinissBjoj
JO ©puoiqo

1 1 1 1 1 i 1 1 1 lisi 1 1 1 1 1 1 1 1

•tunipogjo
optioiqo

t- CO esasfo osio
II 1 11 II 1 Il6 iS \tZ^ 1 18^

•uoji
JO apixojaj

«6 c lort-^diort.^-^.^ loio^A^oM

•BOiUS

3-37
0-42

1-91

1-31

21-99

2910

0-17

64-50

533

54-25

0-8
18-89
29-30
5903

0-69

14-04
0-92

•PPV
oijnqding

0-27

101

0-17
0-26

1-46

0-51

0-83

1-0

2-15

0-59
0-68
0-35
2-16

010
0-99

•ppv

ouoqdsoqj

60-39
46-14

45-53

48-30
49-21
49-32
40-63
38-48
47-29
51-81

382
14-9

1-94

50-1

11-76

18-76

18-19

50-07

54-99

34-96

40-11

•9UIIT

•BIS8U38W

•BpOg

0-44

27-79

10-34

15-75
16-79

4-45

18-89

1301

-8

39-92
10-57
1-31
20-10
1124
0-66
0-71

•qsujoj

25-90
643

2417

30-12
33-84
21-87
3-91
20-91
32-76
11-43
17-19
12-3
1218

3f
14-46
4-00
9-58
8-74
9-53
21-67
25-85

•JU03

iad saqsy

1 1 1 1 1 II 1 1 1 1 1 1 l^bd^l 1 ill

Plants, or parts of
plants.

* Wheat, grain . . .

* Wheat, grain . . .

* Wheat, grain . . .

Wheat, grain . . .

* White wheat grain.

* Red wheat grain .

Barley, grain . . .

* Rye, grain ....

* Rye, straw . . .
Oats, grain . . .

* Oats, straw . . .

Maize, grain . . .
Maize, straw . .

* Mi'let, grain . . .

* Buckwheat, gRxin .

* Madia sativa . . .

* Henipseed ....
♦Linseed

12*

,390

APPENDIX.

1 1

« o e K o

1

3B3 S y h5

gigs

bo

•inntssiijoj
JO ©pijoiqo

•lunipog
JO apjjomo

•uoai
JO opixojaj

•BOins

•ppv

ounqding

•pioV
ouoqdsoTij

"ounq

•BlSGUguj^

•■epog

•Hsvjod

•juao
jad saqsy

0.3

I I I I I I i i I I I I I I I i I I I I I MM

M M M i:^M6M ill II II II II

I I i

:s;??

1 r-cd» I -rfpOM

tb i.T -^ -^ -^ .^ 1^ ih i: ih

ip M O S O I--

( 10 m o >o 'S'

' tb C5 C5 5« i^

!!cio(MO^oi--.>n'^into

»C O C5

ss

— « -sC do cb c-» do do i t^

(j» 05 t^ do -^ D.

o! -^ « *» => ^ r- I di -^

■^ i C!

I- pH I O •>(>« ^

•i (N I « o do

C5 QC X O O I-

55 ®»

Mrs 00

II II II II

^ ,s;sj

I f2c<e»(No<9« I I I

1-2

sigslt

r := .S ~ J= r

-* * ♦ # # ♦ *

S ."Sf 1
S $|s

«! o e IT s

># #•<

APPENDIX.

23

j
Loc ility of 1
tho Plant. ! Analyst.

.i

c

lil li

1

Denninger.
Kleinschuiidt.

Wrighton.

L. Hofmann.
Poleck.

1 ottinger.

1

fl 1 iff

b o5

i

sec; a
v u o «
SS S % %
» « « «

'6 '6 o o

d
O

•juni^srjoj

J > apijomo

•iimp:>H
JO apuoiqo

1 1 1 1 1 l||

5«

^1 1 1 1 1 1 iiii

6^

giinese.

18-17

Red

oxiae
of man-
ganese.

1315 .

1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1

iiiiiliS

o

•UOJ(

JO aptxojaj

!

•"!IIS

2 O CS 5-« -^ -^ r^

1

-p:ov

ojanqding

o 1 -<oo«b 1 Ai

P

•ppV
atjoqd^oqj

51 S SI t>J r- fN 00

1

•auiiT

1

•Kisau3aj^

LO X -* S5 ;^ X ;^

5!

•..pog

c; « '^» i- ■* o
■* w 6* -^ 1 (i< c>

M 1 M C= -^ ih -< 12

g

•i[srioj

Ji3

oliil M

1 1 1 1 1 1 i|

1

a

•i^.g ■ ■ ■ . .

Wood.
Seeds.

Bark.

B.rk.

Wood.

r Seeds.

Wood.

1

. ...->wr

******* 5^

1

o

^5»

APPENDIX.

PolecJ
Levi.
Kiichl

Kochl

Maj-.

i2

1

Giessen
Giessen

Alsace
Zealand

1

Banat

Fiinfkir-
chen

•imiJSSBJOJ

•lunipog
JO apjjoiiio

•noJi
JO apixojoj

•«ains

•PPV
ounndiug

PPV
ouoqdsoqj

•omiq

-msaa3Ki\[

•Bpos

•JISBJOJ

•juao
jad saqsy

»2 0h

a o a

i M M i I I I i i I I I I I I I I I I I III

I I tb I ■* 1 I I -^ M do I tc M 3^ 6< -^ I C5 A( n >o ih ii c»

•^ it T^ 6 di d» «5 •* ■* -Jr ■♦ 6» « -^f >o -Jf o d» 6 -^ I I I I I

l^ l^ rt 'H » >-H I , . I . I I I I I !fl 1— I O Si l^ M t- 00 O

•^ ih o -^ CO M I I I I I I I I 1 I ^ di tb C5 o -^ ift dj ih

I di (N d< -^ d« « M « o rt> « ch « o d« ih "h rs o -^ di «3 o ■*

>5 t^ s: ifl M 'T -r X 3V CJ 3 iS '

COO->1«-sS-H'*t-QOS>rt5lO:

5« 5» -^ '>» rt to O n & « l-» (X)

i~ — 1 C5 -.o ifs ir: 51 1^ M i- S3 o i?5 «fl » t- 1^ « -< 5>
to Ci d« d» d» d» i^ do I- lo CO .^ -i< ih ih d» ih d» ■* «

O lO to — <
r- to QD -v
r- PICS'*

tbtcM J

I I i l6 II I I

1 1

n ^ s:

1*1 {^00

»--^so

is

RSS

oc Ci cr. s: o — I

-r S5 1^ c

SSto^ ,8.^S

I I I I I I I I II \t^.n I

«fO Igj.

I I I

-Si— i

a e-g

■••3 J "

ssrs

1^

APPENDIX.

2o3

■3

B

<

§

.£3
S

S

m

£

I

fa.

Trinidad

Denierara
Island of
Granada

Jamaica

Trelawney

Jamaica

St. James

Jamaica

St. James

young plants

Hoffmans-

gave
Heligoland

Cape
Good Hoi)e
West Indies

III

1 1 I 1 1 1 i

1

1

III- 111

0 s-

1

•uimssnjoj
JO apijomo

•miupog JO
apiiomo

1

I

•luuipog^
joapipoi^

1 1 1

1

1

1 i 1 1 1 1 1

1

I

n 1

00
0

I

•uoji
JO apixoaaj

1 1 M 1 1 1

1

1

iiiii

1 1 1

1

I

^
%

?5

■-tx

SS 1

1

§

•ppv
ounqding

•piaV
ouoqdsoqj

0 i^ 'i I- 1- 0 n

I

1

(jj -t -^ M 0

P3 a

«6 «

i

i

•aiun

do 0 ih -^ (j« .0 0

z

s

•*

000 "H-^ A(

S3 S

i

g
*»

'«|sau3c];\[

s

» 5-? ^ 35 XI
qp -< SJ (J» t;-

6 -j: 55 3 0

IS i

6

0

•vpog

'H ff^ M »b cc •<»< 6«

!£>

i^C5Tt<do 1

si 1

?

0

MSTHOd

do

OM05« 1

!g 1

i

i

'1U33

jad saqsy

i 1 1 1 1 1 1

1

1

'li

1

1

.-e

Sacchaniin IV.

V.

VI.

officinarum VII.

VIII.

IX.

X.

^

M

•a >• c 93 d
##**■§

•snonj[ »J

LRminaria digitata .
EklonJa buccinalis .

Padina pavonia . . .

3

1

>

1-

9

S

1

254

APPENDIX.

i

1

I 1} 1

Locality of
the Plant.

Greenland

Hoffmans-

gave.

Bay of

Campoachy

Atlantic

Ocean

Kattegat

Kattegat

Hoffmans-

gave

Kattegat

Hoffmans-

gave
Kattegat

• G lessen
. Giesseu

1 1 1 1 nil 1 i 1 1 1 1 1 1 1 1 1 1 i 1

•uintssTJioj
JO apuoiqo

Mil 1 1 1 1 1 M i ii^PIII

•tunipog
joopuoiqo

Hi 1 1 1 1 1 i 1 ipi 1 1 1 1 li

•UOJI

JO apixojaj

Ml 1 1 1 1 1 inmmM

•T!3n!S

•ppV
ounqdiug

II IS 1 1 1 ii immimi

s 5 s gi ^ s s s s s,?c;j^?§8ss§?8

•ppV
OFJoqdsoqj

oloo 00666 6^6.^«3t-t-^dD«M

-auiiT
•nisauSBW

r-l 1 Al 6 T^ 61 6 1 6l6t-00®OO-fM'^-«1<t^

•«pog
•qsBjoa

3, gqS ^gS?S? §^S?, 1,11,1
« 1 -^ 6 ■* moooc>;9;oj«illllll

jad saqsy

S '5 S S g S S S S i^ ,gSSi^g8j;g

jl

Fucus vesiculosus . .
Halidrys siliquosa . .

Sargassum vulgare . .

Sargassum cocciferum .

Purcellaria fastigiata .

Chondrus crispus . . .
Chondrus plicatus . .
Iridffia edulis ....
Polysiphonia elongata .

Delesseria sanguinea .

* Datura Stramon. Seeds
*Conium maculat. . .
♦Digitalis purp. . . .

* Chelidonium m . . .

* Agrostemma Gith. . .

* Centaurea Cyanus . .

* Anthemis arvensis
*M-dtricaria i I.

chamomilla S U.

* Acorus Calamms . .

APPENDIX.

355

ANALYSES OF ANIMAL EXCREMENTS.

1000 parts of human feces left 150 parts of ashes (Berzelius), which
consist of : —

Phosphate of lime
Phosphate of magnesia
A truce of gypsum
Sulpliiitc of soda •
Sulphate of p<^ftash .
Pho-sphfitc of soda .
Carbonate of soda
Sihca
Charcoal and loss

Cowdung.

(Ha'dlen.)
Phosphate of lime .... 109
Phosphate of magnesia . . . lO'O
Peroxide of iron . . . . 8"5

Lime 1"5

Gypsum. . . . . . .3-1

Chloride of potassium, copper . traces.

Silica t)3-7

Loss 13

1000

100

150

Phosphate of lime
Carbonate of lime
Phosphate of magnesia
Silica ....

Horsedung.
(Jackson.)
. 50

18-75
. 3625

40

10000

According to Berzelius there are contained in —

Urea

Free lactic acid

Lactate of ammonia ....

Extract of flesh

Extractive matter ....

Uric acid

Mucus of the bladder ....

Sulphate of potash

Sulphate of soda ....

Phosphate of soda .....

Diphosphate of ammonia 1*65

Common salt

Sal ammoniac

Phosphate of magnesia and lime .
Silica

Water

1000 parts

100 parts

Human

5olid residue

Urine

of Urine.

. 3010

44-39

• 1 17-14

25-58

■>vm

1-49

. 032

0-48

3-71

554

. 316

4-72

2-94

439

. 1-65

2-46

4-45

0-64

. 1-50

223

1-00

1-49

. 003

005

10000

93300

10(KM)0

Z5r

APPENDIX

ANALYSES OF URINE BY LEG ANN.*

URINE.

In 1000 Parts. |

B

1

•si

II

m

1 iiS

/

1

5

age

"1 20 years .

93000

30-00

112

4-60

4-42

0-39

0-41

Of a Man
aged

22 years .

928-80

21-88

0-97

2-40

545

0-24

1-64

J>.38 years .

928-30

27-80

1-21

3-70

453

0-47

0-93

86 years .

95300

8-10

0-43

0-70

292

114

0-29

. 85 years .

959-50

13-78

024

1-63

2-92

0-25

0-27

Ofa

1

Woman

^28 years .

953-00

1310

0-24

017

225

1-15

0-46

aged

J

Of a Girl

aged
Ofa Boy

( 19 years .

> 8 years .
S 3 years .

941-00

24-59

0-63

0-80

7-85

2-43

0-62

94800

19-20

0-23

3-80

321

0-52

0-85

aged*

96100

17-30

024

ANALYSES OF URINE BY LEHMANN.f

i

2

if

S .

II

1

1

h\

auality of Urine.

3

1

12

^

■a <u 6

o S

r/2

c

o

M

ja

2 «

<-

t

o 2 ,

Urine in cases of "

934-002

65-998

32-914

1-073

13-J80

3-602

7-289

3-666

1-187'

very strictly re-
gulated ordi-

^937-682

62-318

31-450

1021

14-185

3-646

7314

3-765

1132 ;

nary diet . . . ,

932-019

67-981

32 909

1-098

14-859

3712

7321

3-989

1-108:

Urine frona ani-

909-32

96-68

53-79

1-41

9-36

5-37

11-51

552

3-72 1

mal food ...

933-27

66-73

41-65

1-18

6-62

346

7-08

404

2-70 ;

Urine from vege-
table food . .

929-10

70-90

a3-3i

117

25-70

3-80

7-16

354

1-22 '

^941-91

.58-09

2242

1-01

18-49

307

7-14

3-()8

1-09 ;

934-92

65-08

25-69

0-89

82-62

3-71

7-23

3-74

1-11 1

Urine from non- "
nitrogenized
food . . . ..

.953-98

46-02

18-92

0-89

_

2-74

325

301

1

1-00 1

955-11

34-89 1108

0-54

114

2-98

5-48

0-91

* Simon, medicinlsche Chemie, Part ii., pp. 357 and 358.

t Beitrige zur physiologiscben und pathologist hen Chemie, ^c, von F. SinoD, Vol. I.
p. 180.

APPENDIX

Vo7

URINE OF HERBIVORA. ANALYSES OF VON BIBRA."

In 1000 Parts.

URINE.

Extractive
Matter

Soluble in
Water.

Extractive
Matter

Soluble in
Alcohol.

tS

i

s

1

Of the Horse

II J

Of the Pig .jj;
Of the Ox . j{-
Of the Goat jj;
Of the Hare I.

21-^2

25-50

18-26
3-87
3-99
14 21
10-20
454
468

9-58

23-40 i 18-80

12-44

12-60
123

555

12-00
1-25

0-88

005

006
005
0-07
007
0-06
006
005

-

885-09

912-84
981-96
982i>7
91201
9-2311
980-07
983-99

91286

^ 19-25
1-42
112
22-48
1643
1-00
056

32-68

40
909
8-48

24 42

25-77
8-50
8-70

23-70

00
0-88
0-80
1-50
2-22
0-80
0-40

12-64

8-38
2-73
2-97
19-76
49-21
3-78
0-76

8-54

«

f^

W

H

tf

1^

<:

o

p^

>

o

o

n

>-,

-1-1

!/:

^

<1

<

w

ffi

<<

H

ir;

L^

o

o

t>

pq

M

\A

K

fc

o

w

^

1 'aui-Tl M3K» "I punoj ai9A\ uoji jo saoejx 1

, -ssoT

If

1 £ I

1

1

-BDtHS

ii'

i ^ 1

eg- » '

1

1

•lunipog
JO epuomo

6-94

5f*
with a
little
chloride
of potas-
sium

53-1
0-30

14-7

with a

little
chloride
of potas-
sium

9d

little
chloride
of potas-
sium
22-49

-B;s»a3Ki/\[ JO
aaijqdsoijj

1 I

1 1

t

1 1

t-

-auiiq JO
an.'qdsoiij

1 1

s ■

S

-Bpog JO
ajuqdsoqj

-upog
JO ajBqding

1 1

1 1 '

s

1 1

? 1 I

a

1

•qsuioj
JO 8j«iid(ns

1 1 1

1

1

•UpOg JO

ajwuoqjeo

i

':,

1 1 1

n

1

-qsTj^od JO
ojBuoqjuo

i

^

sil

1

-Bisau3Bi\[ JO
ajBUoqiBQ

05 n

1 1 i

1

1

•ainiq jo
ajBuoqjBo

S 8

10-7

Spur.

1

1

IS

O

Of the Pig .
Of the Ox .
Of the Goat

1

i

♦ Annalen der Chemie und Pharmicie, Vol. liii., p.^.

r Ibid.

258

APPENDIX.

URINE OF HERBIVORA

ANALYSED BY BOUSSINOACLT.*

Pig.
Urea 490

Hippurate of potash t

Lactate of potash not determined

Carbonate of magnesia 087

of lime Spur

SulphMte of potash 198

Phosphate of potash 102

Chloride of sodium 128

Silica 0-07

Water and organic matter not determined . . 979-14

100000

Horse.

Cow.

3100

18-48

4-74

1651

d 2009

1716

41G

4-74

10-82

0-55

118

360

t

t

0-74

152

1-01

Spur

91076

92132

1000-00

GUANO, AFRICAN.

ANALYSED BY TESCHEMACHER.

Volatile ammonia and salts, as oxalate, phosphate, and humate, with animal matters

containing 5 per cent, ammonia 25

Fixed alkaline salts, as chloride, sulphate and phosphate of potassium ... 11

Phosphate of lime and magncsid. 32

Water 30

Earthy matters S

100

GUANO, CHILIAN.

ANALYSED BY COLQUHOUN.

Urate of ammonia, ammoniacal salts, and decomposed animal matter . . 17-4

Phosphate of lime and magnesia, oxalate of lime 48-1

Fixed alkaline salts 10-8

Stony mutters . 1'4

Moisture 22*3

100
{Lond., Edinb., and Dvhl. Phil. Mag., 1S44, May and June)

CHILIAN GUANO.

ANALYSED BY DR. URE.

Combustible, organic, and volatile matter, containing 2i per cent, of ammonia . J&5

Water 24

Silica 0-5

Phosphate of lime 53

100

* Annales de Chimie et der Phys., Septembre, 1845, p. 97.

t Hippuric acid could not be detected even when the pig with its food (potatoes)
\ejffi rations of fresh clover.
X No phosphate could be found.

APPENDIX.

359

PERUVIAN GUANO.

ANALYSED BY DR. IJRE.

Nitrogenised organic matter, including urate of ammonia . . 50

Water 11

Phosphate of lime 25

Phosphate of ammonia and magnesia, phosphate of ammonia,

oxalate of ditto, containing 49 per cent, of ammonia . 13

Silica ..... 1

100
{Lond., Edinb., and Dubl. Phil. Mag., 1844, May and June.)

AFRICAN GUANO.

ANALYSED BY DR. URE.

Saline and organic matter, containing 10 per cent, of ammonia . . .50

Water 21-5

Phosphate of lime and magnesia, also of potash 26

Silica 1

Sulphate of potash and chloride of potassium 1-5

100

{Land., Edinb., and Dubl. Phil. Mag., 1S44, May and June.)

AFRICAN GUANO.

ANALYSED BY DR. URK.

Combustible animal matter 37

Ammonia, chiefly as phosphate 9*5

Alkaline and earthy phosphates 185

Alkaline, chiefly potash salts 6-0

Silica 0*5

Water 285

100

GUANO.

ANALYSED BY KERSTEN.'

Peru.

Combustible matter, of which in No. I. 3 2, in II. 32.
and in III. 6.5 per cent, of humlc acid, and of uric

acid in I. 27 per cent, in the others, traces . . 36*5

Ammonia 8-6

Phosphate of lime and magnesia 205

Phosphate, sulphate, and chloride of potassium and

sodium 6-5

Uuarzy sand . . 1*5

Water . . , 280

100

II.

Peru

HI.

Africn.
Island of
Ichaboc.

350
7-5

22-5

395
95
175

8-2
2-0
250

7-3

1-3

250

100

• Journal of Practical Chemistry. Vol. xxxlv., p. 361.

2 GO

APPENDIX.

OIUTjgjQ

s ? § ? ?
'^5 3 «= <^ S

•OBIU

-omuiv Itig

-uinipog
JO apuomo

29-22

9-50

286-31

•uinissiBioj
JO opiJomo

1 1 1 1 1

-BpOg

JO ajBi^Jxo

105-63

-BIUOIUUIV

}o a»c[uxo

74-0
100-38
93-9
Spur.

JO aiBiidsoiij

1 1 1 1 I

-i?iu(>nuuv
JO ajRqdsoqj

63-3
30-06
61-24

•Bpog
JO ejBqdsoiij

1 ! 1 I §

CO 1

•qsuioj
JO ajnqdsoiij

20-02
77-32
14-94
49-47

-•fipog
JO sjBqding

-qsnoj
JO ainqding

i $ ^ n \z
»^ " i - s

i ' ' ' •

•J3»BAV

§ S § g 8
1 ^ 1 1 -

^ « a

APPENDIX. 2G1

GUANO.

ANALYSED BY DR. J. DAVY

American Africat

Guano. Gaancx

Soluble matters, oxalate, phosphate, and chloride of ammonium,

and animal matters 41-2 40*2

Incombustible and insoluble, chiefly phosphate of lime and of

magnesia 29 28-2

Incombustible, soluble, chloride, carbonate and sulphate of pot-
ash 2-8 6-4

Combustible, sparingly soluble, chiefly urate of ammonia . 19

Expelled by drying ; water and carbonate of ammonia ... 8 25*3

100 100

Davy found no Urea and no Oxalic Acid.

GUANO, AFRICAN.

ANALYSED BY FRANCIS.

Volatile salts, as oxalate and carbonate of ammonia, sal ammoniac, and combusti-
ble organic matter, containing 550 per cent, of humic acid, uric acid, and

extractive matter, and 970 per cent, of ammonia 4259

Water 2713

Phosphate of lime and magnesia 22*39

Sand • . . . 0-81

Alkaline salts, chiefly phosphate, chloride, and a little sulphate of potassium . . 7-08

100
{Land., Edin., and Duhl. Phil. Mag., 1844, May and June.)

ANALYSIS OF A BROWNISH YELLOW GUANO.

BY OELLACHKR.*

Sal ammoniac 2*25

Urate of ammonia . 12-20

Oxalate ditto 17-73

Phosphate ditto 690

Carbonate ditto 0-80

Humate ditto 1-06

Phosphate of ammonia and tnagnesia .... 11-63

Phosphate of lime 20-16

Oxalate of ditto 1-30

Carbonate of ditto 1-65

Chloride of sodium 0-40

Sulphate of potash 4*00

of soda 4-92

Waxy matter 0-75

Sand 1-68

Water 4-31

Undetermined organic matter ... ... 826

100-00
Centralblatt., 1844, p. 17 — Buchner, Reperlorium, vol. ixxii., pp. 289— l2Qk

262

APPENDIX.

2.— CONSTITUENTS SOLUBLE IN HOT WATER, IN 1000 PARTS.

Phosphate
of Lime.

Phosphate
of Soda.

Phosphate

of Am-
monia and
Magnesia.

Uric Acid.

Urate of

Organic
Matter

I.

ir.
in.

1 1-86
2-88

11-37
110

1-20 (?)
1-28 (?)
Spur.
Spur.

5-64
4-04
7-84
Spur.
133

2516

154-18
2512

11-80
6-38
8-60

10-00
7-56

3.— CONSTITUENTS INSOLUBLE IN WATER, IN 1000 PARTS.

"c

o .

^

<«

2 ^
■5.3

CLfcc

B

o

.a

1

Peroxide
Iron and
Alumina

i

11

i
1

1'

I i 197.50
^•\ 19200

20-30

25-60

1560

26-36

34-50

0-44

19-84

107-26

16-48

—

20-60

11-40

42-42

i-50

„ { 62-70
I^- 664-47

8-74

109-58

7-20

—

8-62

—

49-74

4-98

30-56

—

20-43

29-73

—

80-60

268

III. 13113

25-80

4-20

1-50

18-36

—

—

ANALYSES OF ANIMAL EXCREMENTS.

Guano.

A sample

from Liverpool

Bartels.

Sal ammoniac 6-500

Oxalate of ammonia 13-351

Urate of ammonia ... . . 3244

Phosphate of ammonia 6250

Wnxy matter 0600

Sulphate of potash 4227

Sulphate of soda 1119

Phosphate of soda 5291

Phosphate of ammonia and magnesia . . 4-196

Common salt 0100

Phosphate of lime 9 940

Oxalate of lime 16360

Alumina ..'... .0104

Residue insoluble in nitric acid . .. . 5-800
Loss (water, ammonia, undetermined organic

matter) .... ... 22-718

100000

Guano. ]
from Lima

Nightingales'
dung.

Volkel.

Braconnot.

4-2
100
90
60

0-2

52-7 with iwtash
0-8 with potash

55
38

3-3

2-6

143
70

0-2
0-8

4a

4-7

323

37-7

APPENDIX. 263

ANALYSES OF THE ASHES OF THE SOLID EXCREMENTS OF
THE HORSE.

BY JOHN ROBINSON ROGERS.

The fresh excrements consist of—

Organic matter 19-68

Inorganic matter or ashes 3-07

Water . . 7725

10000

In 100 parts of the ashes there are contained of matter-
Soluble in water 3-16

Soluble in hydrochloric acid 22-59

Insoluble in both 74-45

100-00

COMPOSITION IN 100 PARTS.

Of the Matter
soluble in Water
^nd in Acid.
Silica . . .... 6-13

Potash .... 24-55

Soda 0-00

Oxide of iron 442

Lime 14-91

Magnesia. . , . . 10-70

Oxide of manganese . . . 0-00

Phosphoric acid . . 37-54

Sulphuric acid . , . 1-99

Chlorine . ... o-14

Of the Residue,

insc uble in Water

Of the whole

and Acid.

Ash together

81-92

62-40

6-71

11-30

2-67

1-98

005

117

1-06

4-63

1-46

384

2«7

2-13

111

10-49

1-78

189

0-00

0-U3

037

014

100-00 lOOOO

264

APPENDIX.

MARLE.

ANALYSES BY DR. K. O. F. KROCKER *

The locality of the differen t kinds is on the left bank of the Rhine, between
Mayence and Worms.

'•

II.

HI.

IV.

V.

VI.

vn.

Carbonate of lime. .
Carbonate of mag- t

nesia .... J

Potash

Water

• Clay, sand, & oxide )

of iron. ... J
Ammonia ....

12-275

0-975

0-087
2-036

84-525

0-0047

14-111

Spuren.

0082
2-146

82-830

0-0077

18-808

1-228

0092
2-111

76-827

0-0988

20-246

3211

0091
1311

74-325

0-0768

2.5-176

2-223

0105
1-934

69-570

0-736

32143

1-544

0101
1-520

64-214

00955

36066

1-106

0163
1555

60-065

00579

TABLE OF THE AMMONIA CONTAINED IN THE SOIL

BY DR. KROCKEK.T

Ammonia
in 100 parts

of Earth

dried in the

Air.

Ammonia in a
stratum of solid

Soils examined.

Specific
Gravity.

Matter 0 25

metre thick, on

1 hectare, in

pounds.

Clay soil, before manuring

0-170

2-39

30314

Clay soil

0-163

2-42

19733

Surface soil, at Hohenheim .

0-156

2-40

^^-^

Subsoil of the same field .

0104

2-41

12532

Clay soil, before manuring

0-149

2-41

17953

Clay soil, before manuring .

0147

2-<l

17713

Clay ready to be sowed with barloy

0-143

2-44

17446

Clay soil, before manuring .

0139

2-<l

16749

Loamy soil, before manuring .

0-135

2-45

16537

LoHniy soil, before manuring

0-1 M

2-45

16292

Earth from America, never manured .

P-llO

2-18

12614

Sandy soil, never cultivated

0-096

2-50

12000

Loamy earth, dug out ....

0088

25

11000

Sandy soil, never cultivated

0056

2-51

7028

Nearly pure sand

0031
0-0988

2-61

4045
11952

00955

11552

0-0768

9288

Marie . .\

0-0736 ^

2-42

8904

0-0579

7004

00077

931

0-0O17

568

* Annalen der Chemie und Pharmacie vol. Ivii., p.
t Ibid., vol. Iviii., 1846.

PART II.

THE CHEMICAL PROCESSES OP FERMENTATION, DECAY.
AND PUTREFACTION.

CHAPTER L

( • hom ira I Tnt nsJbrmations,

WooDV fibre, sugar, gum, and all such organic compounds,
suffer certain changes when in contact witli other bodies — that
is, they suffer decomposition.

There are two distinct modes in which these decompositions
take place in organic chemistry.

When a substance composed of two compound bodies, crystal-
lized oxalic acid for example, is brought in contact with concen-
trated sulphuric acid, a complet*^' decomposition is effected upon
the application of a gentle heat. Now, crystallized oxalic acid
is a combination of water with the anhydrous acid ; but concen-
trated 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, anhydrous oxalic acid is set free ; but, as this acid cannot
exist in a free state, a division of its constituents necessarily
ensues, by which carbonic acid and carbonic oxide are produced,
and evolved in the gaseous form in equal volumes. In this
example, the decomposition is the consequence of the removal
of two constituents (the elements of water), which unite with
the sulphuric acid, and its cause in the superior affinity of the
acting body (the sulphuric acid) for water. In consequence of
the removal of the component parts of water, the remaining ele-
13

206 CHEMICAL TRANSFORMATIONS.

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 con-
stituents of a compound, is quite analogous to the decomposition
of inorganic substances. When we bring sulphuric acid and
nitrate of potash together, nitric acid is separated in consequence
of the affinity of sulphuric acid for potash; in consequence,
therefore, of the formation of a new compound (sulphate of
potash).

In the second form of these decompositions, the chemical
affinity of the acting body causes the component parts of the
decomposing body to combine, so as to form new compounds, of
which either both, or only one, combine with the acting body.
Let us take dry wood, for example, and moisten it with sulphuric
acid ; after a short time the wood is carbonized, while the sul-
phuric acid remains unchanged, with the exception of its being
united with more water than it possessed before. Now, this
water did not exist as such in the wood, although its elements,
oxygen and hydrogen, were present ; but by the chemical attrac-
tion of sulphuric acid for water, they were in a certain measure
compelled to unite in this form; and, in consequence of this, the
"carbon of the wood was separated as charcoal.

Hydrocyanic acid and water, in contact with hydrochloric
acid, are mutually decomposed. The nitrogen of the hydrocy-
anic acid, and the hydrogen of a certain quantity of the water,
unite together and form ammonia ; whilst the carbon and hydro-
gen of the hydrocyanic acid combine with the oxygen of the
Water and produce formic acid. The ammonia combines with
the muriatic acid. Here the contact of muriatic acid with water
and hydrocyanic acid causes a disturbance in the attraction of
the elements of both compounds, in consequence of which they
arrange themselves into new combinations, one of which — am-
monia— possesses the power of uniting with the acting body.

Inorganic chemistry can pr^isent instances analogous to this
class of decomposition also ; but there are forms of organic che-
ihical decomposition of a very different kind, in which none of
Ihe component parts of the decomposing matter enter into combi-

EXAMPLES. 261

nation with the body which determines the decomposition. In
cases of this kind a disturbance is produced in the mutual attrac-
tion of the elements of a compound, and they, in consequence,
arrange themselves into one or into several new combinations,
which are incapable of suffering further change under the same
conditions.

When, by means of the chemical affinity of a second body, by
the influence of heat, or through any other causes, the composi-
tion 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 meta-
morphosis. It is an essential character of chemical transforma-
tions, that none of the elements of the body decomposed are
singly set at liberty.

The changes 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

966 CHEMICAL TRANSFORMATIONS.

CHAPTER II.

On the Causes which effect Fermentation, Decay,* and Putrefaction.

Attention has been only recently directed to the fact, that a
body in the act of combination or decomposition exercises an in-
fluence upon any other body with which it may be in contact.
Platinum, for example, does not decompose nitric acid ; it may
be boiled with this acid without being oxidized by it, even when
in a state of such fine division that it no longer reflects light
(black powder of 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 undergo the same change ;
or, in other words, the latter body, from its contact with the
oxidizing silver, acquires the property of decomposing nitric
acid.

Copper does not decompose water, even when boiled in
dilute sulphuric acid ; but an alloy of copper, zinc, and nickel,
dissolves easily in this acid with evolution of hydrogen gas.

Tin decomposes nitric acid with great facility, but water with
difficulty ; and yet, when tin is dissolved in nitric acid, hydro-
gen 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 decompo-
sition which can be explained by chemical affinity s the last. In
the other cases, electrical action ought to have retarded or pre-

* An essential distinction is drawn in the followhig part of the work,
between decay and putrefaction ( Verwesung und Fdulniss), and they are
shown to depend on different causes ; but as the word decay is not gene-
rally applied to a distinct species of decomposition, and does not indicate
its true nature, I shall in future, at the suggestion of the author, employ
the term eremacatms (from iipifta by degrees, and «av«is burring). — ^Bld.

THEIR CAUSE. 2G9

vented the oxidation of the platinum or copper while they were
in contact with silver or zinc, but, as experience shows, the in-
fluence of the opposite electrical conditions is more than counter-
balanced by chemical action.

The same phenomena are seen in a less dubious form in com-
pounds, the elements of which are held together by a feeble
affinity. It is well known that there are chemical compounds,
of so unstable a nature, that changes in temperature and elec-
trical condition, or even simple mechanical friction, or contact
with bodies apparently totally indifferent, cause such a disturb-
ance in the attraction of their constituents, that the latter enter
into new forms, without any of them combining with the acting
body. These compounds appear to stand but just within the
limits of chemical combination, and agents exercise a powerful in-
fluence on them, which are completely devoid of action on com-
pounds of a stronger affinity. Thus, by a slight increase of tem-
perature, the elements of hypoclj4orous acid separate from one
another with evolution of heat and light ; chloride of nitrogen
explodes by contact with many bodies, which combine neither
with chlorine nor nitrogen at common temperatures ; and the
contact of any solid substance is sufficient to cause the explosion
of iodide of nitrogen, or of 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. The 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
inertia, and any shock or movement is sufficient to destroy the
attraction of their component parts, and consequently their ex-
istence as definite compounds.

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 nto combination with any of its con

870 CHEMICAL TRANSFORMATIONS.

stituents. In this respect, its decomposition depends evidently
upon the same causes. as those which effect that of iodide of ni-
trogen, or of 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
decomposition, and has been ascribed to a new power termed the
CATALYTIC FORCE. Now, it has Hot been considered, that the
presence of the platinum and silver serves here only to accele-
rate the decomposition ; for without the contact of these metals,
the peroxide of hydrogen decomposes spontaneously, although
very slowly. The sudden separation of the constituents of per-
oxide of hydrogen differs from the decomposition of gaseous
hypochloious acid, or solid iodide of nitrogen, only in so far as
the decomposition takes place in a liquid.

A remarkable action of peroxide of hydrogen has attracted
much attention, because it differs from ordinary chemical phe-
nomena. This is the reduction which certain oxides suffer by
contact with this substance, on the instant at which the oxygen
separates from the water. The oxides thus easily reduced, are
those of which the whole, or part at least, of their oxygen is re-
tained merely by a feeble affinity, such as the oxides of silver
and of gold, and peroxide of lead.

Now, other oxides very stable in composition, effect the decom-
position of peroxide of hydrogen, without experiencing the small-
est change ; but when oxide of silver is employed to effect the
decomposition, all the oxygen of the silver is carried away with
that evolved from the peroxide of hydrogen, and as a result of
the decomposition, water and metallic silver remain. When
peroxide of lead is used for the same purpose, half its oxygen
escapes as a gas. Peroxide of manganese may in the same man-
ner be reduced to the protoxide, with the liberation of oxygen, if
there be present an acid to exercise an affinity for the protoxide
and convert it into a soluble salt. If, for example, 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 on examining the solution, we find a salt of the protoxide of

TL EIR CAUSE. 271

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 metallic silver remains in
the state of a black powder. (Berzelius.)

Now no other explanation of these phenomena can be given,
than that a body hi the act of combination or decomposition ena-
bles 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 con-
tact with it ; and if these atoms are capable of the same change
as the former, they likewise undergo that change ; and combina-
tions and decompositions are the consequence. But when the
atoms of the second body are not of themselves capable of such
an action, any further disposition to change ceases from the
moment at which i^»e atoms of the first body assume the state of
rest, that is, when the changes or transformations of this body are
quite completed.

This influence exerted by one compound upon the other, is
exactly similar to that which a body in the act of combustion
exercises upon a combustible body in its vicinity ; with this dif-
ference only, that the causes which determine the commencement
and duration of the condition of change are different. For the
cause, in the case of the combustible body, is heat, which is
generated every moment anew ; whilst in the phenomena of
decomposition and combination, which we are considering at pre,
sent, the cause is a body in the state of chemical action, which
exerts the decomposing influence only so long as this action
continues.

Numerous facts show that motion alone exercises a consi-
derable influence on chemical forces. Thus, the power of
cohesion does not act in many saline solutions, even when
ihey are fully saturated with salts, if they are permitted to
cool whilst at rest. In such a case, the salt dissolved in a liquid

273 CHEMICAL TKANSKOKMATlUNS.

does not crystallize; but when a grain of sand is thrown into
the solution, or when it receives the slightest movenneiit, the whole
liquid becomes suddenly solid with the evolution of heat. 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 ineriicE so as to arrange themselves into cer-
tain forms. A dilute solution of a salt of potash, mixed with tar-
taric acid, yields no precipitate whilst at rest ; but if the motion
is communicated to the solution by agitating it briskly, crystals
of cream of tartar are instantly deposited. A solution of a salt
of magnesia also, though not rendered turbid by the addition of
phosphate of ammonia, deposits 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 decomposition under
consideration, motion, by overcoming the vis inertice, 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 certain 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 appear to present themselves,
in conditions, and with properties, different from those which
they possess when they obey the natural attractions of their atoms.
Thus sugar and glass, when m Ited and cooled rapidly, are
transparent, of a conchoidal fracture, and elastic and flexible to
a certain degree. Put the ormer becomes dull and opaque on
keeping, and exhibits, by cleavage, crystalline faces which belong
to crystallized sugar. Glass assumes also the same condition,
when kept soft by heat fur a long period ; it becomes white,
opaque, and so hard as to strike fire with steel. Now, in both
these bodies, the atoms evidently have diflerent positions in the
two forms. In the first form their attraction did not act in the di-
rection in which their power of cohesion was strongest. It is
know^n also, that when sulphur is melted and cooled rapidly by

THEIR CAUSE. 273

throwing it into cold water, it remains transparent, elastic, and so
soil 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 sul-
phur returns again into the crystalline condition, without any
assistance from an exterior cause ; a fact which shows that their
molecules have assumed another position, and that they possess,
therefore, a certain 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
composition as calcareous spar, but of which the hardness and
crystalline form prove that its molecules are arranged in a dif-
ferent manner. When a crystal of arragonite is heated, an inte-^
rior motion of its molecules 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 disturbance of the state of
the equilibrium, in consequence of which the particles of the
body put in motion obey either other affinities, or their own
natural attractions.

But if it be true, as we have just shown it to be, that mecha-
nical motion is sufficient to cause a change of condition in many
bodies, it cannot be doubted that a body in the act of composition
or decomposition is capable of imparting the same condition of
motion or activity, in which its atoms are, to those of certain
other bodies: or, in other words, of enabling other bodies with
which it is in contact to enter into combinations, or suffer de-
compositions.

The reality of this influence has been already sufficiently
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, putrefaction, and erebiacausis,

are meant those changes in form and properties which compound

organic substances, undergo when separated from the organism,

and expend to the influence of water and a certain temperature.

13*

274 CHEMICAL TRANSFORMATIONS.

Fermentation and putrefaction are examples of the kind of <ie-
csomposition which we have named transformations ; the elements
of the bodies capable of undergoing these changes arrange theov*
selves into new combinations, in which the constituents of water
generally take a part.

Eremacausis (or decay) differs from fermentation and putre-
faction, 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 transformation of those matters which evolte gaseous
products without odor, are now, by pretty general consent, desig-
nated by the term fermentation ; whilst to spontaneous decom-
position of bodies which emit gases of a disagreeable smell, the
term putrefaction is applied. But the smell is, of course, no
distinctive character of the nature of the decomposition, for both
fermentation and putrefaction are processes of decomposition of
a similar kind, the one of substances destitute of nitrogen, the
other of substances containing that element.

It has also been customary to distinguish from fermentation
and putrefaction a particular class of transformations, viz. those
whose conversions and transpositions are effected without the
evolution of gaseous products. But the conditions under which
the products of the decomposition present themselves are purely
accidental ; there is therefore no i eason for the distinction jusi
mentioned.

FERMENTATION AND PUTREFACTION. 17»

CHAPTER 111.

Fermentation and Putrefaction.

Several bodies appear to enter spontaneously into the states
of fermentation and putrefaction, particularly such as contain
nitrogen. Now it is very remarkable that very small quantities
of these substances, in a state of fermentation or putrefaction,
possess the power of causing unlimited quantities of similar mat-
ters to pass into the same state. Thus, a small quantity of the
juice of grapes in the act of fermentation, added to a large
quantity of the same fluid, which is not fermenting, induces the
!>tate 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 de-
compositions effected by chemical affinity ; they are chemical
actions, conversions, or decompositions, excited by contact with
bodies already in the same condition, in which the elements, in
consequence of the disturbance, arrange themselves anew, ac-
cording to their affinities. In order to form a clear idea of these
processes, analogous but less complicated phenomena must pre-
viously be studied.

The compound nature of the molecules of an organic body,
and the phenomena presented by them when in relation with other
matters, point out the true cause of these transformations. Evi-
dence is afforded even by simple bodies, that in the formation of
combinations, the force with which the combining elements ad-
here to one another is inversely proportional to the number of
simple atoms in the compound molecule. Thus^prgiU^i^^.jjf

270) CHEiMICAL TRANSFORMATIONS.

lijangancse by absorption of oxygen is converted into the sesqui-
oxide, the peroxide, manganic and hypermanganic acids, the
number of atoms of oxygen being augmented by ^, by 2, by 3,
and by 3^. But all the oxygen contained in these compounds,
beyond that whicii belongs to the protoxide, is bound to the man-
ganese by a much more feeble affinity ; ii red lieat causes an
evolution of oxygen from the peroxide, and tljc manganic and
hypermanganic acids cannot be separated from their bases with-
out undergoing immc-diate decomposition.

There are many facts wliich prove, lliat the most simple inor-
ganic compounds are also the inost stable, and undergo decom-
position with the greatest difficulty, whilst those of a complex
composition yield easily to changes and decompositions. The
cause of this evidently is, that in proportion to the number of
atoms which enter into a compound, the directions in which their
attractions act will be more numerous.

Whatever ide.'is we may entertain regarding the infinite divisi-
bility of matter in general, the existence of chemical proportions
removes every doubt respecting the presence of certain limited
groups or masses of matter which we have not the power of divid-
ing. The particles of matter called equivalents in chemistry
are not infinitely small, for they possess a weight, and are capa-
ble 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 instances according to the direction
and place, which the simple atoms take in the compound mole-
cules.

When we compare tlie com{X)sition 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 equivalents are united. Thus, the compound atom of an or-
ganic acid of very simple composition, acetic acid for example,
contains twelve equivalents of simple elements ; one atom of kinic
acid contains thirty-three ; one of sugar thirty-six ; one of amyg-
dalin ninety; and one of stearic acid 138 equivalents. The
coniponent parts of animal bodies are infinitely more complex
eveii than the^.

OF ORGANIC COMPOUNDS. 277

Inorganic compounds differ ffom organic in as great a degree
in their other characters as in their simplicity of constitution.
Thus, the decomposition of a compound atom, as of sulphate of
potash, is aided by numerous causes, such as the power of cohe-
sion, or the capability of its constituents to form solid, insoluble,
or at certain temperatures volatile compounds with the body
brought into contact with it, and nevertheless a vast number of
other substances produce in it not the slightest change. Now, in
the decomposition of a complex organic atom, there is nothing
similar to this.

The empirical formula of sulphate of potash is SKO4. It con-
tains 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 re-
place one of the constituents of the compound by another sub-
stance. But we cannot produce a different arrangement of the
atoms, because they are already disposed in the simplest form in
which it is possible for tliem to combine. Now, let us compare
the composition of sugar of grapes with the above: here 12 eq.
of carbon, 12 eq. of hydrogen, and 12 eq. of oxygen, are united
together, and we know that they are capable of combining with
each other in the most various ways. From the formula of sugar,
we might consider it either as a hydrate of carbon, wood, starch,
or sugar of milk, or further, as a compound of ether with alcohol,
or of formic acid with sachulmin.* Indeed we may calculate
almost all the known organic compounds destitute of nitrogen
from sugar, by simply adding the elements of water, or by re-
placing any one of its elementary constituents by a different sub-
stance. The elements necessary to form these compounds are
therefore contained in the sugar, and they must also possess the
power of forming numerous combinations amongst themselves by
their mutual attractions.

Now, when we examine what changes sugar undergoes when
brought into contact with other bodies which exercise a marked
influence upon it, we find that these changes are not confined to

* The black precipitate obtained by the action of hydrochloric aci4 on

2T!8 CHEMICAL TRANSFORMATIONS.

any narrow limits, like those of inorganic bodies, but are in ftict
unlimited.

The elements of sugar yield to every attraction, and to each
in a peculiar manner. In inorganic compounds, an acid acts
upon a particular constituent of the body which it decomposes,
by virtue of its affinity for that constituent, and never resigns its
proper chemical 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 ex-
isting in the sugar, but by disturbing the equilibrium in the mu-
tual attraction of the elements of the sugar amongst themselves.
Muriatic and sulphuric acids, which differ so much from one
another, both in characters 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 di-
lute, 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 acid. 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 sub-
jected to the action of alkalies, a whole scries of different new
products are obtained ; while oxidizing agents, such as nitric acid,
produce from it carbonic acid, acetic acid, formic acid, sac-
charic 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 ofierto 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 inerticR 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 compounds as sugar, compounds there

OF ORGANIC COMPOUNDS. 279

fore possessing a very complex molecule, which are capable
of undergoing the decompositions named fermentation and putre-
faction.

We have seen that certain metals acquire a power which they
do not of themselves possess, namely, that of decomposing watei
and nitric acid, by simple contact with other metals in the act of
chemical combination. We have also seen, that peroxide of
hydrogen and the persulphuret of the same element, in the act of
decomposition, cause other compounds of a similar kind, but of
which the elements are much more strongly combined, to undergo
the same decom positron, although they exert no chemical affinity
or attraction for them or their constituents. The cause pro-
ducing these phenomena will be also recognised, by attentive ob-
servation, in those matters which excite fermentation or putrefac-
tion. All bodies in the act of combination or of decomposition
have the property of inducing those processes ; or, in other words,
of causing a disturbance of the statical equilibrium in the attrac-
tions of the elements of complex organic molecules, in consequence
of which those elements group themselves anew, according to
their special affinities.

The proofs of the existence of this cause of action can be easily
produced ; they are found in the characters of the bodies which
effect fermentation and putrefaction, and in the regularity with
which the distribution of the elements takes place in the subse-
quent 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 simplest of the compounds of nitrog,<;n, suffices to
illustrate the whole of the transformations of organic bodies; of
those in which nitrogen is a constituent, and of tho$e in which it
is absent.

«80 CHEMICAL TRANSFORMATIONS.

CHAPTER IV.

On the Transformation of bodies which do not contain Nitrogen as A
constituent ; and of those in which it is present

When oxygen and hydrogen, combined in equal equivalents, as
in steam, are conducted over charcoal, heated to the temperature
at which it possesses the power to enter into combin.ition with one
of these elements, a decomposition of the steam ensues. An
oxide of carbon (either carbonic oxide or carbonic acid) is under
tall circumstances formed, while the hydrogen of the water is
liberated. This proves that the attraction between carbon and
oxygen is more powerful, at a high temperature, than that be-
tween oxygen and hydrogen. The carbon here is not shared
between the elements of the water ; for no carburetted hydrogen
is formed.

Acetic and meconic* acids suffer a true transformation under
the influence of heat, that is, their component elements are dis-
united, and form new compounds without any of them being
singly disengaged. Acetic acid is converted into acetone and
carbonic acid C 4 H, Oj=C3 H, O + CO2), and meconic acid
into carbonic acid and komenic acid ; whilst, by the influence
of a higher temperature, the latter is further decomposed into
pyro-meconic acid and carbonic acid.

Now, in these cases, the carbon of the bodies decomposed is
shared between the oxygen and hydrogen ; part of it unites with
the oxygen and forms carbonic acid, whilst the other portion en-
ters into combination with the hydrogen, and an oxide of a hydro-
carbon is formed, in which all the hydrogen is contained.

Tn a similar manner, when alcohol is exposed to a gentle red
heat, its carbon is shared between the elements of the water ;

* An add existing in opiuni} and named from the Greek for poppy.

OF BODIES NOT CONTAINING NITROGEN. 28 1

an oxide of a hydro-carbon which contains all the oxygen
(aldehyde), and some gaseous compounds of carbon and hydro-
gen, being produced.

It is evident that during the transformation caused by heat, no
foreign affinities can be in play, so that tlie new compounds must
result merely from the elements arranging themselves, accord-
ing 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 pro-
ducts of two bodies, similar in composition but different in pro-
j>erties, subjected to transformations under the influence of two
different causes, we find that the manner in which the atoms are
transposed is absolutely the same m both.

In the transformation of wood in marshy soils, by what
we call putrefaction, its carbon is shared between the oxygen
and hydrogen of its own substance, and of the water : car-
buretted hydrogen is consequently evolved, as well as carbonic
acid, both of which compounds have an analogous composition
(CH„ COJ.

Thus also, in the transformation of sugar called fermentation,
its elements are divided into two porticMis ; the one, carbonic acid,
contains -f of the oxygen of sugar ; and the other, alcohol, con-
tains all its hydrogen.

In the transformation of acetic acid, produced by a red heat,
carbonic acid, containing f of the oxygen of the acetic acid, is
formed, and acetone, containing 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 entering into action ; or, in other words, that
the products differ ad infinitum^ according to the composition of
the origmal substance.

CHEMICAL TRANSFORMATIONS.

ON THE TRANSFORMATION OF BODIES CONTAINING
NITROGEN.

By the examination of the substances most prone to fermenta-
tion and putrefaction, it is found that they are all, without excep-
tion, bodies containing nitrogen. In many of these compounds,
a transposition of their elements occurs spontaneously as soon as
they cease to form part of a living organism ; that is, when they
are drawn out of the sphere of attraction in which alone they are
able to exist.

There are, indeed, bodies destitute of nitrogen which possess
a certain degree of stability only when in 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 attractions. Hyper-
manganic, manganic, and hyposulphurous acids, belong to this
class of substances, which however are rare.

The case is very different with azotized bodies. It woald
appear that there is, in the nature of nitrogen, some peculiarity
which gives its compounds the power to decompose spontaneously
with so much facility. Now, nitrogen is known to be the most
indifferent of all the elements : it evinces no particular attraction
to any one of the simple bodies : and this character it preserves
in all its compounds, a character which explains the cause of its
easy separation 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 diminished, 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 nitro-
gen, and in all fulminating compounds.

All other azotized substances acquire the same power of de-
composition, when the elements of water are brought into play ;
and indeed the greater part of thtm are not capable of trans-

OF BODIES COxNTTAlNlNG NITROGEN. 283

formation, while this necessary condition to the transposition of
their atoms is absent. Even the compounds of nitrogen most
liable to change, such as those found in animal bodies, do not
enter into a state of putrefaction when dry.

The result of the known transformations of azotized substances
proves, that water does not merely act as a medium in which
motion is permitted to the elements in tlie act of transposition,
but that its influence depends on chemical affinity. When the
decomposition of such substances is effected with the assistance
of water, their nitrogen is invariably liberated in the form of
ammonia. This is a fixed rule, without any exceptions, what-
ever 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 temperature produce the same effect. It
is only when there is a deficiency of water, or of its elements,
that cyanogen or other azotized compounds are produced.

From these facts it may be concluded, that ammonia is the
most stable compound of nitrogen ; and that hydrogen and nitro-
gen 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 substances des-
titute of nitrogen, we have recognised the great affinity of carbon
for oxygen as a powerful 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 organic com-
pounds, while the great affinity of nitrogen for hydrogen fur-
nishes a new and powerful cause of change, and thus facilitates
the transposition of their component parts. Thus, in the bodies
destitute of nitrogen we have one element, and in those contain-
ing that substance, two elements which mutually share the ele-
ments of water. Hence there are two opposite affinities at play,
which mutually strengthen each other's action.

Now we know, that the most powerful attractions may be over-
come by the influence of two affinities. Thus, a decomposition
of alumina may be effected with the greatest facility, when the
affinity of charcoal for oxygen, and of chlorine for aluminium,
are both put in action, although n*^ither of these alone has any

284 CHEMICAL TRANSFORMATIONS.

influence upon it. There is in the nature and constitution of the
compounds of nitrogen a kind ol tension of their component
parts, and a strong disposition to yield to transformations, which
effect spontaneously the transposition of their atoms from the
instant that water or its elements are brought in contact with
them.

The characters of the hydrated cyanic acid, one of the sim-
plest 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
carbon, nitrogen, hydrogen, and oxygen, in such proj)ortions, that
the addition of a certain quantity of the elements of water is ex-
actly sufficient to cause the oxygen contained in the water and
acid to unite with the carbon and form carbonic acid, and 'the
hydrogen of the water and acid to combine with the nitrogen and
form ammonia. The most favorable conditions for a complete
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 effer-
vescence.

This decomposition may be considered as the type of the trans-
formations 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 transforma-
tions.

Putrefaction assumes a totally different and much more com-
plicated form, when the products at first formed undergo a further
change. In these cases the process consists of several stages, of
which it is impossible to determine when one ceases and the other
begins.

The transformations of cyanogen, a body composed of carbon
and nitrogen, and the simplest of all the 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 pu-
trefaction of an azotized body which has been at all accurately
studied.

A solution of cyanogen in water becomes turbid after a short

OF BODIES CONTAINING NITROGEN. 285

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 inso-
luble in water, and is thus enabled to resist further change.

A second transformation is effected by the cyanogen being
shared between the elements of the water, in consequence of
which CYANIC ACID is formed by a certain quantity of the cyano-
gen combining with the oxygen of the water ; while hydrocya-
nic ACID is also formed, by another portion of the cyanogen unit-
ing with the hydrogen thus liberated.

Cyanogen experiences a third transformation, by which a com-
plete 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 immedi-
ately into carbonic acid and ammonia. The cyanic acid, how-
ever, newly formed in the decomposition of cyanogen, escapes
this decomposition by entering into combination with the free am-
monia, by which means urea is produced.

The hydrocyanic acid is also decomposed into a brown matter
containing hydrogen and cyanogen, the latter in greater propor-
tion than in the gaseous hydrocyanic acid. Oxalic acid, urea,
and carbonic acid, are also formed by its decomposition, and
formic acid and ammonia are produced by the decomposition of
its radical.

Thus, a substance consisting of only two elements (carbon and
nitrogen) yields, in contact with water, eight totally different pro-
ducts. Several of these products are formed by the transforma-
tion of the original body, its elements being shared between the
constituents of water ; others are produced in consequence of a
further change in 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 elements have as-
sisted.

These examples show that the results of decomposition by fer-
mentation and putrefaction comprehend very different pheno-
mena. The first kind of transformation is the transposition of

HH CHEMICAL TRANSFORMATIONS.

the elements of one complex compound, by which new com-
pounds 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 matter before transformation are found,
of with them an excess, consisting of the constituents of watfer
which had assisted in promoting the disunion of the elements.

The second kind of transformations consists of the transposi-
tions of the atoms of two or more complex compounds, by which
the elements of both arrange themselves mutually into new pro-
ducts, with or without the co-operation of the elements of water.
In this kind of transformations, the new products contain the sum
of the constituents of all the compounds which had taken a part
in the decomposition.

The first kind of decomposition characterizes the proper fer-
mentation ; the other, that which is called putrefaction. We shall,
in the following pages, use these terms invariably for these two
kinds of metamorphosis, which are essentially different in their
results.

FERMENTATION OF SUGAR. 387

CHAPTER V.

Fermentation of Sugar.

The peculiar decomposition of sugar may be viewed as a type
of all the transformations designated fermentation.*

The analysis of sugar from the cane, proves that it contains
the elements of carbonic acid and alcohol, minus 1 atom of water.
The alcohol and carbonic acid produced by the fermentation of
a certain quantity of sugar, contain together one equivalent of
oxygen and one equivalent of hydrogen ; the elements, therefore,
of one equivalent of water more than the sugar contained. The
excess of weight in the products is thus explained most satisfac-
torily ; 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, botli from the proportions in which it unites with bases,
and from the composition of saccharic acid, the product of its
oxidation. Now none of these atoms of carbon are contained in

* When yeast is made into a thin paste with water, and 1 cubic centi-
mitre of this mixture introduced into a graduated glass receiver filled with
mercury, in which are already 10 grammes of a solution of cane-sugar,
containing 1 gramme of pure solid sugar ; it is found, after the mixture
has been exposed for 24 hours to a temperature of from 20 to 25 C. (68 —
77 F.), that a volume of carbonic acid has been formed, which, at 0° C.
(32^^ F.), and an atmospheric pressure indicated by 07G 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, 256 — 261 cubic centimetres of carbonic
acid are obtained. This volume of carbonic acid corresponds to from
0-503 to 0-5127 grammes by weight. Thenard also obtained from 1 gramme
of sugar 0-5262 grammes of absolute alcohol. 100 parts of cane-sugar
yield, therefore, of alcohol and carbonic acid together 103*89 parts. Now
in these two products are contained 42 parts of Carbon, or exactly th*
quantity originally present in the sugar.

i58 FERMENTATION OF SUGAR.

the sugar as carbonic acid, because the whole quantity is obtaineo
as oxalic acid, when sugar is treated with hypermanganate of pot-
ash (Gregory) ; and as oxalic acid is a lower degree of the oxi-
dation of carbon than carbonic acid, it is impossible to conceive
that the lower degree should be produced from the higher, by
means of one of the most powerful agents of oxidation which we
possess.

It can be also proved, that the hydrogen of the sugar does not
exist in it in the form of alcohol, for it is converted into water
and a kind of carbonaceous 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 carbonic acid, so
that these bodies must be produced by a different arrange-
ment 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 ap-
preciable part in the transposition of the elements of the sugar ;
for in the products resulting from the action, we find no compo-
nent part of this substance. The same sugar which in contact
with yeast yields alcohol and carbonic acid gives rise, when in
contact with putrefying white cheese, to butyric acid, hydrogen
being at the same time liberated. (Pelouse and Gelis.)

We may now study the fermentation of a vegetable juice, con-
taining not only saccharine matter, but also such substances as
albumen and gluten. The juices of parsneps, beet-roots, and
onions, are well adapted for this purpose. When such a juice is
mixed with yeast at common temperature, it ferments like a solu-
tion. 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 decomposition at a temperature of
from 95° to 104° (35° — 40° C). Gases possessing an offensive
smell are evolved in considerable quantity, and when the liquor
is examined after the decomposition is completed, no alcohol can
be detected. The sugar has also disappeared, and with it all the
azotized compounds which existed io the i^^9^ previously to ita

YEAST OR FERMENT. -889

fermentation. Both ^vere decomposed at the same time ; the
nitrogen of the? azotized compounds remains in the liquid as am-
monia, and, in addition to it, there are three new products, formed
from the component parts of the jui<je. One of these is lactic
acidr the slightly volatile compound found in putrid animal mix-
tures ; the other is the crystalline body which forms tiie principal
cpBstituent of manna ; and the tiiird is a mass resembling gum-
af abic, 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 tiiey are not produced from the elements of the sugar
alone. None of these three substances could b6 detected in the
juice before fermentation. They must, therefore, have been
ibrmed 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 i^ directed to the condition of those substances
which possess the power of inducing fermentation and putre-
faction in other bodies, evidence is 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 trans-
position.

The characters of the remarkable matter deposited in an inso.
iuble state during the fermentation of beer, wine, and vegetable
juices, may first be studied.

This substance, called yeast or ferment, from the power
which it possesses of causing fermentation in sugar, or saccha-
rine vegetable juices, possesses all the characters of a com-
pound OF NITROGEN IN THE STATE OF PUTREFACTION AND ERBMA-
CAUflS.

14

;tf90 YEAST OR FERMENT.

Like wood in the state of eremacausis, yeast converts the
oxygen of the surrounding air into carbonic acid, but it also
evolves this gas from its own mass, like bodies in the state of
putrefaction. (Colin.) When kept under water, it emits car.
bonic acid, accompanied 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 water is quite necessary for sustaining the proper-
ties of ferment, for by simple pressure its power to excite fer-
mentation is much diminished, and is completely 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, substances, all
of which possess antiseptic properties.

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 fer-
mentation.

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, without either 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
^50LUBLE part. But before it obtains this power, the decanted
infusion must be allowed to cool in contact with the air, and to
remain some time exposed to its 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 ai/.
and cfirbonic acid may be found in it after a short time.

Yeast produces fermentation in consequence of the pro-

ITS PROPERTIES. 291

gressive decomposition which it suffers from the action of ail
and water.

Now when yeast is made to act on sugar, it is found that
after the completion of the transformation of the latter substance
into carbonic acid and alcohol, part of the yeast itself has dis-
appeared.

From 20 parts of fresh yeast from beer, and 100 parts of
sugar, Th6nard obtained, after the fermentation 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 properties of woody
fibre, and had no further action on sugar.

It is evident, therefore, that, during the fermentation of sugar
by yeast, both of these substances suffer decomposition at the
same time, and disappear in consequence. But if yeast be a
body which excites fermentation by being itself in a state of
decomposition, all other matters in the same condition should
have a similar action upon sugar ; and this is in reality the case.
Muscle, urine, isinglass, osmazome, albumen, cheese, gliadine,
gluten, legumin, and blood, when in a state of putrefaction, all
have the power of producing the putrefaction or fermentation of
a solution of sugar. Yeast, which by continued washing has
entirely lost the property of inducing fermentation, regains it
when its putrefaction has recommenced, in consequence of its
being kept in a warm situation for some time.

Yeast and putrefying animal and vegetable matters act as
peroxide of hydrogen does on oxide of silver, when they induce
bodies with which they are in contact to enter into the same
state of decomposition. The disturbance in the attraction of the
constituents of the peroxide of hydrogen effects a disturbance
in the attraction of the elements of the oxide of silver, the one
being decomposed on account of the decomposition of the
other.

Peroxide of hydrogen is rapidly decomposed in contact with
moist fibrin of blood, an animal substance in a continuous state
of decomposition. The oxygen which it contained, in addition
to that necessary to form water, escaped with violent effer.
vescence.

399 YEAST OR FERMENT.

. 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 pmportion 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 insolu-
bility 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 existence 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 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
satisfactorily for many known phenomena. ■■■^.

A large quantity of hippuric acid may be obtained . from the
fresh urine of a horse, by the addition of 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 asparagus, licorice-root, or the root of marshmallow (AWuHKl,
officinalis).

DIFFERENCE OF FERMENTATION AND PUTREFACTION. 293

It has also 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 dis*
united ; 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 destitute 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, iti
a certain measure, more highly organized atoms.

Every azotized constituent of the animal or vegetable organism
runs spontaneously into putrefaction, when exposed to moisture
and a high temperature.

Azotized matters are, accordingly, the only causes of fermen-
tation and putrefaction in vegetable substances.

Putrefaction, on account of its defects, as a mixed transforma-
tion of many different substances, may be classed w ith the most
powerful processes of deoxidation, by which the strongest affini^^
ties are overcome.

When a solution of gypsum in water is mixed with a decoc-
tion of sawdust, or any other organic matter capable of putrefac-
tion, and preserved in well-closed vessels, it is found after some
time, that the solution no longer contains sulphuric acid, but in
its place carbonic and free hydrosulphuric acids, between which
the lime of the gypsum is shared. In stagnant water containing
sulphates in solution, crystallized pyrites are 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 decom-
posed water are liberated either in a pure state, or as carburetted
hydrogen.

It is evident, that if M'ith the water a substance containing a
jarge quantity of oxygen, such as sulphuric acid, be also present,
the matters in the state of putrefaction will make use of the oxy

S94 YEAST OR FERMENT.

gen 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 hydrosulphurio
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 (Insatis 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 the juice of the beet-
root and other plants containing sugar, contains the same number
of equivalents of carbon and hydrogen as the sugar of grapes, but
two atoms less of oxygen ; and it is highly probable that it is pro-
duced from sugar of grapes, contained in those plants, in precisely
the same manner as indigo-blue is converted into deoxidized
white indigo.

During the putrefaction of gluten, carbonic acid and pure hy-
drogen gases 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 decomposition begins again,
and in addition to the salts just mentioned, carbonate of ammonia
and a white crystalline micaceous matter (caseous oxide) are
formed, together with hydrosulphate of ammonia, and a mucila-
ginous substance coagulable by chlorine. Lactic acid is almost
always produced by the putrefaction of organic bodies.

We may now compare fermentation and putrefaction with the
decomposition which organic compounds suffer under the influence
of a high temperature. Dry 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 con-
taining a large proportion of hydrogen are necessarily produced.
Fermentation may be considered as a process of combustion or
oxidation of a similar kind, taking place in a liquid between the
elements of the same matter, at very slightly elevated temperature ;
and putrefaction as a process of oxidation, in which the oxygen
of all the substances present comes into play.

EREMACAUSIS, OR DECAY. 299

CHAPTER VL

Blremacausis, or Decay.

In organic nature, besides the processes of decomposition named
fermentation and putrefaction, another and not less striking class
of changes occurs, which bodies suffer from the influence of the
air. This is the act of gradual combination of the combus-
tible elements of a body with tlie oxygen of the air ; a slow
combustion or oxidation, to which we shall apply the term of
eremacausis.

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 ani-
mal 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, conse-
quently, their eremacausis. The tendency to undergo this
change is possessed in the highest degree by substances contain-
ing nitrogen.

When vegetable juices are evaporated by a gentle heat in the
air, a brown or brownish-black substance is precipitated as a pro-
duct of the action of oxygen upon them. This substance, which
appears to possess similar properties from whatever juice it is ob-
tained, has received the name o^ 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 pulverulent brown substance is formed, and is
known by the name of htimus.

S9« EREMACAUSIS, OR DECAY;

The conditions which determine the commencement of erema*
causis are of various kinds. Many organic substances, par-
ticularly such as are mixtures of 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 matters already in a state
of decay.

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 sub-
stances, empyreumatic oils, and oil of turpentine, possess a simii.
lar action in this respect. The latter substances have the same
eifect on decaying bodies as on phosphuretted hydrogen, the spon-
taneous 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 oxy-
gen, and are converted into a brown substance like humus, evol-
ving 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 substance, not in
the form of ammonia.

All these facts show that the action of oxygen seldom affects
the carbon of decaying substances, and this 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 sufficient to combine
with its hydrogen, the carbon is not burned, but is separated as
lamp-black ; while, if the quantity of oxygen is not sufficient even
to consume all the hydrogen, new compounds are formed, such
M naphthalin and similar matters, which contain a smaller pro.

EXAMPLES OF. 397

portion of hydrogen than those compounds of carbon and hydrogen
which previously existed in the combustible substance, 'i^-'-'^w"

There is no example of carbon combining directly with oxygeli
at common temperatures, but numerous facts show that hydrogen,
in certain states of condensation, possesses that property. Lamp-
black which has been heated to redness may be kept in contact
with oxygen gas, without forming carbonic acid ; but lamp-black,
impregnated with oils contgiining 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 con-
tained in it 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. i& i {<>•::

The matters subject to eremacatisis may be divided into two
classes. The first class comprehends those substances which
unite with the oxygen of the air, without evolving carbonic acid ;
and the second, such as emit carbonic acid while they absorb
oxygen, • .mairry ti-T r - : >. . r ij .txis.iiH4tJ> vif' -nib rid ,f;^Uis £w«*\A9 9<J1

When the ofl of bitter almonds is exposed to thd air, it atsdft^
two equivalents of oxygen, and is converted into benzoic acid ^
but half of the oxygen absorbed combines with the hydrogen of
the oil, and forms water, which remains in union with the anhy-
drous benzoic acid.

According to the experiments of Dobereiner, 100 parts of
pyrogallic acid absorb 38*09 parts of oxygen when in contact
with ammonia and water; the acid being changed in conse-
quence of this absorption into a mouldy substance, which contains
less oxygen than the acid itself. It is evident that the substance
formed is not a higher oxide ; and it is found, on comparing the
quantity of the oxygen absorbed with that of the hydrogen con-
tained ill the acid, that they ai*e exactly in the proportions for
forming water.

When colorless orcin is exposed together with ammonia to thft
contact of oxygen gas, the beautiful red-colored orcein is produe»
14*

SOS EREMACAUSIS, OR DECAY.

-ed. Now, the only changes which take place here are, that the
absorption of oxygen by the elements of orcin and ammonia
causes the formation of water ; 1 equivalent of orcin Ci, H, |
Oj, and 1 equivalent of ammonia NHj, absorb 5 equivalents
of oxygen, and 5 equivalents cf water are produced, the compo-
sition of orcein being Cjg H, O^ N. (Dumas.) In this case
it is evident, that the oxygen absorbed has united merely with
the hydrogen.

But, although it appears very probable that the oxygen acts
primarily and principally upon hydrogen, the most combustible
constituent of organic matter in the state of decay ; still it can-
not thence be concluded that the carbon is quite devoid of the
power to unite with oxygen, when every particle of it is surround-
ed 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 contact with hydrogen in eremacausis a property which
it does not itself possess at common temperatures. But the
formation of carbonic acid during the eremacausis of bodies con-
taining hydrogen, must in most cases be ascribed to another cause.
It appears to be formed in a manner similar to the formation of
acetic acid, by the eremacausis of saliculite of potash. This salt,
when exposed to a moist atmosphere, absorbs 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.

An alkaline solution of hsematin being exposed to an atmo-
sphere 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
^ese 6 cubic centimeters of carbonic acid contain only an equal
volume of oxygen, so that it is certain from this experiment that

FORMATION OF CARBONIC iCID.

J 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
hsBinatin, and had separated from the other elements as carbonic
acid.

The experiments of De Saussure upon the decay of woody
fibre show that such a separation is highly probable. Moist
woody fibre evolved one volume of carbonic acid for every
volume of oxygen which it absorbed. It has just been mentioned
that carbonic acid contains its 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 sam&
as if pure charcoal had combined directly with oxygen. But
the characters of woody fibre show, that the elements of water
are not contained in it in the form of water ; for, were this the
case, starch, sugar, and gum must also be considered as hydrates
of carbon.

But if the hydrogen does not exist in woody fibre in the form
of water, the direct oxidation of the carbon cannot be considered
as at all probable, without rejecting all the facts established by
experiment regarding the process of combustion at low tempera-
tures.

If we examine the action of oxygen upon a substance con-
taining a large quantity of hydrogen,. such as alcohol, we find
most distinctly, that the direct formation of carbonic acid is the
last stage of its oxidation, and that it is preceded by a series of
changes, the last of which is a complete combustion of the hy-
drogen. Aldehyde, acetic, formic, oxalic, and carbonic acids,
form a connected chain of products arising from the oxidation of
alcohol : and the successive changes which this fluid experi-
ences 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 formic acid, oxalic acid
is produced ; and the latter acid is converted into carbonic acid
by uniting with an additional portion of oxygen. All these pro-
ducts appear to be formed simultaneously, by the action of oxid*

300 EREMACAUSIS OR DECAY;

ftsin^ agents on aloohcl ; b»it it can Bcarcely be doubted, that the
ferritiatibn of the last product, -he carbonic acid, does not take
p'lac^ until all the hydrogen has been abstracted. ^ "'

The absorption of oxygen by drying oils certainly does not
depend upon the oxidation of their carbon ; for in raw walnut-
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 O.tygen gas absorbed.

Tt must he remembered, that combustion or oxidation at low
temperatures produces results quite similar to combustion at
high temperatures with limited access of air. The most
combustible element of a compound exposed to the action of
oxygen, must become oxidized first, for its superior combustibility
is caused by its being enabled to unite with oxygen at a tempera-
ture at which the other elements cannot enter into that combina-
tion ; this property having the same eifect as a greater affinity.

The combustibility of potassium is no measure of its affinity
for oxygen ; we have reason to believe that the attraction of
magnesium and aluminium for oxygen is greater than that of
potassium for the same element; but neither of those metals
oxidizes either in air or water at common temperatures, whilst
potassium decomposes water with great violence, and appropriates!
its oxygen.

Phosphorus and hydrogen combine with oxygen at ordinary
temperatures, the first in moist air, the second when in contact
with finely-divided platinum ; while charcoal requires a red heat
before it can enter into combination with oxygen. It is evident
that phosphorus and hydrogen are more combustible than char-
coal, that is, that their affinity for oxygen at common tempera-
TURES is greater ; and this is not the less certain, because it is
found, that carbon in certain other conditions shows a much
greater affinity for oxygen than either of those substances.

In putrefaction, the conditions are evidently present, under
which the superior affinity of carbon for oxygen comes into
play ; neither expansion, cohesion, nor the gaseous state, oppostes
it, whilst in eremacaiisis all these restraints have to be over,
come. ri-.ct?.'aft .

The evolution of carbonic acid; dtiring the decay or erenia«

ITS CAUSE. Hi

causis 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 fermen-
tation and putrefaction. While the hydrogen of the substance
is removed and oxidized by eremacausis, carbon and oxygen
separate from the remaining elements in the form of carbonic
acid.

The eremacausis of such substances is, therefore, a decom-
position analogous to the putrefaction of azotized bodies. For in
these there are two affinities at play ; the affinity of nitrogen for
hydrogen, and that of carbon for oxygen, and both facilitate the
disunion of the elements. Now there are two affinities also in
action in those bodies which decay with the evolution of carbonic
acid. One of these affinities is the attraction of the oxygen of
the air for the hydrogen of the substance, which corresponds to
the attraction of nitrogen for the same element ; and the other is
the affinity of the carbon of the substance for its oxygen, which
is constjant under all circumstances.

When wood putrefies in marshes, carbon and oxygen are
separated from its elements in the form of carbonic acid, and
hydrogen in the form of carburetted hydrogen. But when wood
decays or putrefies in the air, its hydrogen does not combine with
carbon, but with oxygen, for which it has a much greater affinity
at common temperatures.

Now it is evidently owing to the complete similarity of these
processes, that decaying and putrefying bodies can mutually re-
place one another in their reciprocal actions.

All putrefying bodies pass into a state of decay when exposed
freely to the air, and all decaying matters into that of putrefac-
tion 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.

•a».. mmt^v^ir »»^9*:^' i^,9iniJi v

592 EREMACAUSIS OR DECAY.

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 fermentation and putrefaction, do not
in reality suffer those changes without some previous disturbance
in the attraction of their elements. Eremacausis always pre-
cedes fermentation and putrefaction, and it is not until after the
absorption of a certain quantity of oxygen that the signs of a trans-
formation in the interior of the substances show themselves.

It is a very general error to suppose that organic substances
have the power of undergoing change spontaneously, without the
aid of an external cause. When they are not already in a state
of change, it is necessary, before they can assume that state, that
the existing equilibrium of their elements should be disturbed ;
and the most common cause of this disturbance is undoubtedly
the atmosphere which surrounds all bodies.

The juices of the fruit or other parts of a plant prone to de-
composition, retain their properties unchanged as long as they
are protected from immediate contact with the air, that is, as
long as the cells or organs in which they are contained 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 fermenta-
tion 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 expressed under a receiver

OF BODIES DESTITUTE OF NITROGEN. 308

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 neces-
sary to cause its fermentation, still this change did not ensue
when the juice was heated in close vessels to the temperature of
boiling water. When thus treated, it could be preserved for
years without losing its property of fermenting. A fresh expo-
sure to the air at any period caused it to ferment.

Animal food of every kind, and even the most delicate vege-
tables, may be preserved unchanged if heated to the temperature
of boiling water in vessels from which the air is completely ex-
cluded. Food thus prepared has been kept for fifteen years, and
upon opening the vessels after this long time, has been found as
fresh and well-flavored as when originally placed in them.

The action of the oxygen in these processes of decomposition
is very simple ; it excites changes in the compositiot of the
azotized matters dissolved in the juices ; — the mode of combina-
tion 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 effects the mutual decomposition of two salts, the crystalli-
zation of salts from their solution, or the explosion of fulminating
mercury. It causes the state of rest to be vxMiverted into a state
of motion.

When this condition of intestine motion is once excited, the
presence of oxygen is no longer necessary. The smallest parti-
cle 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 fermentation or putrefaction
proceeds uninterruptedly to its completion.

Aldehyde attracts oxygen from the air, and, by the process of
eremacausis, becomes vinegar ; if the air be now excluded, the
disturbance already begun is not arrested, but the products are
very different. Two substances are then formed by a change in

304 EREMACAUSIS OR DECAY

the arrangement of the elements. Their composition is similari
but they are very unlike in character.

The contact of ammonia and of alkalies in general maybe
mentioned among 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 ab-
sorbs oxygen with much rapidity, and acquires a brown color.
The alcohol is found after a short time to contain acetic acid,
formic acid, and the products of the decomposition of aldehyde
by alkalies, including the resin of aldehyde, 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 as-
sume 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 eremacausis, converts the
oxygen gas surrounding it into carbonic acid, without change of
Volume. Now, De Saussure added a certain quantity of hydro-
gen 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 oxygen, but a cor-
responding quantity of carbonic acid gas had not been formed.
The hydrogen and oxygen had disappeared in exactly the
same proportion as that in which they combine to form water ;
a true combustion of the hydrogen, therefore, had been induced
by mere contact with matter in the state of eremacausis. Thfe
action of the decaying substance here produced results exactly

OF BODIES DESTITUTE OF NITROGEN. 305

similar to those effected by spongy platinum ; but that they pro-
ceeded from a different cause was shown by the fact that the
presence of carbonic oxide, which arrests completely the action
of platinum on a mixture of oxygen and hydrogen, did not re-
tard in the slightest degree the combustion of the hydrogen in
contact with the decaying bodies.

But t)\e same bodies were found by De Saussure not to pos-
sess 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 com-
pletely all their influence.

Let us suppose a volatile substance containing a large quanti-
ty of hydrogen to be substituted for the hydrogen gas in Dc
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 con^ustion would be sooner
completed. This principle is in reality attended to in the manu-
factories in which acetic acid is prepared according to the new
plajn. In the process 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 conditions are not sufficient to
effect its oxidation. The alcohol must either be in contact with
decaying wood, or must contain a substance which is with facility
changed by the oxygen of the air, and either enters into erema-
causis by mere contact with oxygen, or by its fermentation or
putrefaction yields products possessed of this property. A small
quantity of beer, acescent wine, a decoction of malt, honey, and
numerous other substances of this kind, possess the action
desired.

The difference in the nature of the substances possessing 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 their 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 j exactly

806 EREMACAUSIS OR DECAY

as in the case of an alloy of platinum and silver dissolving in
nitric acid, in which the platinum becomes oxidized by virtue of
an inductive action exercised upon it by the silver in the act of
its oxidation. In the preparation of vinegar, the hydrogen of
alcohol, with the formation of water and evolution of heat, is
oxidized at the expense of the oxygen in contact with it ; the
residue is aldehyde, a substance possessing as great an affinity
for oxygen as sulphurous acid, and by uniting directly with the
latter, it produces acetic acid.

OF BODIES CONTAINING NITROGEN. 807

CHAPTER VIII.

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
process of the eremacausis of such substances. Azotized organic
matter always contains carbon and hydrogen, both of which
elements have a very strong affinity for oxygen.

Now nitrogen possesses a very feeble affinity for oxygen, so
that it is placed, in regard to that element, in a position similar
lo that of the carbon of bodies containing much hydrogen during
their combustion ; 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 moist azotized animal matter is exposed to the action
of air, ammonia is constantly liberated ; nitric acid is never
formed under these circumstances.

But when alkalies or alkaline bases are present, a union of
oxygen with the nitrogen takes place under the same circum-
stances, and nitrates are formed together with the other products
of oxidation.

Although we see the most simple means and direct methods
employed in the great processes of decomposition occurring 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 substance remains
unaltered in a whole series of phenomena, there is no reason to

ms EREMACAUSIS OR DECAY

ascribe a new character to it, for the purpose of explaining a sin-
gle 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, possesses the power of combining
directly with oxygen, and of thus forming nitric acid ; but we
are not acquainted with a single fact which justifies this opinion.
It is only by the interposition of a large excess of hydrogen in
the state of combustion or oxidation, that nitrogen can be con-
verted into an oxide.

When a compound of nitrogen and carbon, such as cyanogen,
is burned in oxygen gas, its carbon alone is oxidized ; and when
it is conducted over a metallic oxide heated to redness, an oxide
of nitrogen is very rarely produced, and never when the carbon
is in excess. Kuhlmann found in his experiments, that it was
only when cyanogen was mixed with an excess of oxygen gas,
and conducted over spongy platinum, that nitric acid was gene-
rated.

Kuhlmann could not succeed in causing pure nitrogen to conN
bine directly with oxygen, even under the most favorable cir-
stances ; thus, with the aid of spongy platinum at different tem-
peratures, 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 compound of hy-
drogen and nitrogen) cannot be exposed to the action of oxygen,
without the formation of an oxide of nitrogen, and production of
nitric acid, in consequence of this union.

It is owing to the great facility with which ammonia is
converted into nitric acid, that it is so difficult to obtain a cor-
rect determination of the quantity of nitrogen in a compc«*imd
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 the red-hot
oxide of copper, it is converted, either completely or partially,
into binoxide of nitrogen.

When ammoniacal gas is conducted over peroxide of manga-

OF BODIES CONTAINING NITROGEN. 309

nese or iron heated to redness, a large quantity of nitrate of am-
monia is obtained, if the ammonia be in excess ; and the same
decomposition happens when ammonia and oxygen are together
passed over red-hot spongy platinum.

It appears, therefore, that the combination of oxygen with
nitrogen occurs rarely during the combustion of compounds of
the latter element with carbon, but that nitric acid is always a
product when ammonia is present in the substance exposed to
oxidation.

The cause wherefore the nitrogen in ammonia exhibits such
a strong disposition to become converted into nitric acid is un-
doubtedly that the two products, which are the result of the oxi-
dation of the constituents of ammonia, possess the power of unit-
ing with one another. Now this is not the case in the combus-
tion of compounds of carbon and nitrogen ; here one of the pro-
ducts is carbonic acid, which, on account of its gaseous form,
must oppose the combination of the oxygen and nitrogen, by
preventing tlieir mutual contact, while the superior affinity of its
carbon for the oxygen during the act of its formation will aid
this effect. »?iV^ ^oi;

When sufficient access of air is admitted during the combus-
tion 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 nitrifi-
cation, since nitric cannot exist without it.

Eremacausis is a kind of putrefaction, differing from the com-
mon 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
always assumes the form of ammonia, and that in this form nitro-
gen 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 source of the formation
of nitric acid on the surface of the earth.

Azotized animal matter is not, therefore, the immediate cause
of nitrification ; it contributes to the production of nitric acid

$lt EREMACAUSIS OR DECAY.

only in so far as it is a slow and continued source of am-
monia.*

Now it has been shown in the former part of this work, that
ammonia is always present in the atmosphere, so that nitrates
might thence be formed in substances which themselves con-
tained no azotized matter. It is known also, that porous sub-
stances possess generally the power of condensing ammonia ;
there are few ores of iron which do not evolve ammoniacal pro-
ducts when heated to redness, and ammonia is the cause of the
peculiar smell perceived upon moistening aluminous minerals.
Thus, ammonia, 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 oxida-
tion of ammonia are combined. It is probable that other orga-
nic 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 ab-
sence of all matter capable of eremacausis.

From the preceding observations on the causes of fermenta-
tion, putrefaction, and decay, we may now draw several conclu-
sions calculated to correct the views generally entertained re-
specting the fermentation of wine and beer, and several other
important processes of decomposition occurring in nature.

* According to the observations of Collard de Martigny, ammonia if
converted directly into nitric acid when in contact with hydrate of lime
and with air, without the intervention of any decaying substance.

YEAST FROM BEER AND WINE. 311

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 decomposition of the sugar contained in the
fluid. But it was also stated, that the process once commenced,
continues until all the sugar is completely decomposed, quite
independently of any further influence of the air.

In addition to the alcohol and carbonic acid formed by the fer-
mentation of the juice, there is also produced a yellow or grey
insoluble substance, containing a large quantity of nitrogen. It
is this body which possesses the power of inducing fermentation
in a new solution of sugar, and which has in consequence re-
ceived the name o^ ferment.

The alcohol and carbonic acid are produced from the elements
of the sugar, and the ferment from those azotized constituents of
the juice 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 J of carbonic acid, and J of pure hydro-
gen gas ; ammoniacal salts of several organic acids were formed
at the same time. Water must, therefore, be decomposed 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 decomposi-
tions of the most energetic kind. Neither ferment, nor any
substance similar to it, is formed in this case ; and we have seen
that hydrogen is not evolved in the fermentation of saccharine
vegetable juices.

It is evident that the decomposition which gluten suffers in an
isolated state, and that which it undergoes when dissolved in a

312 ' ViN(m§ ftlMEfl^T^rfo^. '

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 certain conditions, by free exposure
to the air, without the presence of fermenting sugar. It is known
also that the juice of grapes, or vegetable juices in general, be-
come turbid when in contact with air, before fermentation com-
mences ; and this turbidity is owing to the formation of an
insoluble precipitate of the same nature as ferment.

From the phenomena observed during the fermentation of wort,"*
it is known with perfect certainty that ferment is formed from
gluten at the same time that the transformation of the sugar is
effected ; for the wort contains the azotized matter of the corn,
namely, gluten in the same condition as it exists in the juice of*
grapes. The wort ferments by the addition of^ yeast, but after its
decomposition is completed, the quantity of ferment or yeast is
found to be thirty times greater than it originally was.

Yeast from beer and. that from wine, examined under the mi-
croscope, present the same form and general appearance. They
are both acted on in the same manner by alkalies and by 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 putrefaction of
gluten, has been completely proved. The tendency of the carbon
of the gluten to appropriate the oxygen of water must therefore
always be in action, whether the gluten is decomposed in a soluble
or insoluble state. These considerations, therefore, as well as
the circumstance which all the experiments made on this subject
appear to point out, that the conversion of gluten to the insoluble
state is the result of oxidation, lead us to conclude that the oxy^
gen consumed 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 fermentation of wine and beer is not taken from
the atmosphere.

0/5 ■■''' ''■'■ ■ ' -■• •■•■ ■ ■ ; ' .:-,... ..

,. * Wort is an infusion of malt; it consists of the soluble parts o^, ^iiyi*
substance dissolved in water.

OILY AND ETHEREAL PRODUCTS. 313

The fermentation of pure sugar in contact with yeast must evi-
dently be a very different process from the fermentation of wort
or of must*

In the former case, the yeast disappears during the decompo-
sition of sugar ; but in the latter, a transformation of gluten
is effected at the same time, by which ferment is generated.
Thus yeast is destroyed in the one case, but is formed in the
other.

Now, since no free hydrogen gas can be detected during the
fermentation of beer and wine, it is evident that, since the oxida-
tion 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; either the hydrogen liberated must enter into new
combinations, or by the dcoxidation of the sugar, new compounds
containing a large proportion of hydrogen, and small quantity of
oxygen, together with the carbon of the sugar, must be formed.

It is well known that wine and fermented liquors generally
contain, in addition to the alcohol, other 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 distinguishing
wine from all other fermented liquids are known to depend upon
an ether of a volatile and highly combustible acid ; the ether is
of an oily nature, and has received the name CEnanthic ether.
It is also ascertained that tiie smell and taste of brandy from corn
and potatoe are owing to a peculiar oil, the oil of potatoe spirit
This oil is more closely allied to alcohol in its properties, than to
any other organic substance.

These bodies are })roducts of tlie deoxidation of the substances
dissolved in the fermenting liquids ; they contain less oxygen
than sugar or gli.'en. but are remarkable for their large propor-
tion of hydrogen.

CEnanthic acid contains an equal number of equivalents of
carbon and hydrogen, exactly the same proportions of these
elements, therefore, as sugar, but by no means the same pro-
portion of oxygen. The oil of potatoes contains much more
hy4r(^en.

* The liquid expressed from grapes when fully ripe is called rnuit
15

314 VINOUS FERMENTATION.

Although it cannot be doubted that these volatile liquids are
formed by a mutual interchange of the elements of gluten and of
sugar, in consequence, therefore, of a true process of putrefac-
tion, still it is certain, that other causes exercise an influence
upon their production and peculiarities.

The substances in wine to which its taste and smell are owing,
are generated during the fermentation of the juice of such grapes
as contain a certain quantity of tartaric acid ; they are not found
in wines free from all acid, or which contain a different organic
acid, such as acetic acid.

The wines of warm climates possess no odor ; wines grown in
France have it in a marked degree, but in the wines from the
Rhine the perfume is most intense. The kinds of grapes on the
Rhine, which ripen very late, and scarcely ever completely, such
as the RiESSLTNG and Orleans, have the strongest perfume or
bouquet, and contain, proportionally, a larger quantity of tartaric
acid. The wines from the earlier grapes, such as the Ru-
LANDER, and others, contain a large proportion of alcohol, and
are similar to Spanish wines in tlieir flavor, but they possess no
houquel.

The grapes grown at the Cape from Riesslings, transplanted
from the Rhine, produce an excellent wine, which does not, how-
ever, possess the aroma peculiar to the Rhenish wine.

It is evident, from these facts, that the acid of wines, and their
characteristic perfumes, have some connexion, for they are al-
ways found together ; and it can scarcely be doubted that the
presence of the former exercises a certain influence on the for-
mation of the latter. This influence is very plainly observed in
the fernientation of liquids destitute of tartaric acid, and particu-
larly of those which are nearly neutral or alkaline, such as the
mash* of potatoes or corn.

The brandy obtained from corn and potatoes contains an
ethereal oil of a similar composition in both, to which these li-
quors owe their peculiar smell. This oil is generated during the
fermentation of the mash; it exists ready formed in the fer-

* Mash is the mixture of malt, potatoes, and water, in the mash tun, a
large vessel in which it is infused.

ODORIFEROUS PRODUCTS. 315

mented liquids, and distils over with alcohol when a gentle heai
is applied.

It is observed that a greater quantity of alcohol is obtained
when the mash is made quite neutral by ashes or by carbonate
of lime, and that the proportion of oil in the brandy also is in-
creased.

Now, it is known that brandy made from potatoe starch, which
has been converted into sugar by dilute sulphuric acid, is com-
pletely free from the potatoe oil, so that this substance must be
generated in consequence of a change suffered by the cellular
tissue of the potatoes during their fermentation.

Rxpei'ience has shown that the simultaneous fermentation or
putrefaction of the cellular tissue, by which this oil is gene-
rated, may be completely prevented in the fabrication of brandy
from corn.

The same malt, which in the preparation of brandy yields a
fluid containiag the oil ol" which we are speaking, affords, in the
formation of beer, a spirituous liquor in which no trace of that oil
can be. detected. The principal difference in the preparation of
the two liquids is, that in the fermentation of wc^, an aromatic
substance (hops) is added, and it is certain that its presence
modifies the transformations which take place. Now, it is known
that the volatile oil of mustard, and the empyreumatic oils, arrest
campletely the action of yeast ; and although the oil of hops does
not possess this property, still it diminishes, in a great degree, the
influence of decomposing azotized bodies upon the conversion of
alcohol into acetic acid. There is, therefore, reason to believe
that some aromatic substances, when added to fermenting mix-
tures, are capable of producing very various modifications in the
nature of the products generated.

Whatever opinion, however, may be held regarding the origin
of the volatile odoriferous substances obtained in the fermenta-
tion of wine, it is quite certain that the characteristic smell of

* In the manufactory of M. Dubrunfaut, so considerable a quantity of thi»
oil is obtained under certain circumstances from brandy made from potatoes
that it iQ'ght be employed for the purpose of illuminating his whole manu -
facton'.

316 VINOUS FERMENTATION.

wine is owing to an ether of an organic acid, resembling one of
the fatty acids (oenanthic ether).

It is only in liquids containing other very soluble acids, that
the fatty acids and cenanthic acid are capable of entering into
combination with the ether of alcohol, and of tlius producing
compounds of a peculiar smell. This ether is found in all wines
containing a free acid, but 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 ounanthic ether
could not be formed.

The greatest part of the oil of brandy made from corn con-
sists of a fatty acid not converted into ether ; it dissolves oxide
of copper and metallic oxides in general, and combine* with the
alkalies.

The principal constituent of this oil is an acid identical in
composition with cenanthic acid, but different in properties.
(Mulder.) It is formed in fermenting liquids, which, if they be
acid, contain only acetic acid, a body which has no influence in
causing other acids to form ethers.

The oil of brandy made from potatoes is the hydrate of an
organic base analogous to ether, and capable, therefore, of enter-
ing into combination with acids. It is formed in considerable
quantity in fermenting liquids possessing an alkaline reaction ;
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 generally accompanied by
substances of an offensive odor ; bui the most remarkable exam-
ple of the generation of a true ethereal oil is seen in the fermen-
tation of the Centaurium minus, a plant destitute of smell. When
it is exposed in water to a slightly elevated temperature it fer-
ments, and emits an agreeable penetrating odor. By the distil,
lation of the liquid, an ethereal oily substance of great voletility
is obtained, which excites a pricking sensation in the eyes, and
a flow of tears (Buchner).

We know that most of the blossoms and vegetable substances
possessing a smell owe this property to a volatile oil existing in

THE BAVARIAN PROCESS. 3n

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 inodorous. It is only
during their oxidation tliat they emit their characteristic odor of
garlic. The oil of the berries of the elder-tree, many kinds of
oil of turpentine, and oil of lemons, possess a smell only during
their oxidation or decay. The same is the case with many
blossoms ; and Geiger has shown, that the smell of musk i'^;
owing to its gradual putrefaction and decay.

It is also probable, that the peculiar odorous principle of many
vegetable substances is newly formed during the fermentation of
the saccharine juices of the plants. At all events, it is a fact,
that very small quantities of the blossoms of the violet, elder,
linden, or cowslip, added to a fermenting liquid, are sufficient to
communix3ate 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 particu-
lar plants to ferment along with the wort. On the Rhine, also,
an artificial houquet is often given to wine for fraudulent pur-
poses, 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 dissipated.

The juice of grapes grown in different climates differs not only
in its proportion of free acid, but also in respect of the quantity of
sugar dissolved in it. The quantity of azotized matter in the juice
seems to be the same in whatever part the grapes may grow ; at
least, no difference has been observed in the amount of yeast
formed during fermentation in the south of France, ard 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 into alcohol and
carbonic acid. A certain quantity of the sugar consequently

318 VINOUS FERMENTATION.

remains mixed with the wine in an undecomposed state, the con-
dition necessary 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 solu-
tion.

This gluten gives the wine the property of becoming spon-
taneously 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 the stil ling-casks deposits yeast, it can still be caused to
ferment by the addition of sugar, but old well-cleared wine has
lost this property, because the condition necessary for fermenta-
tion, namely, a substance in the act of decomposition or putre-
faction, is no longer present in it.

In hotels and other places where wine containing much gluten
is drawn gradually from at 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 diff*er from one another in the same
way as the wines.

English, French, and most of the German beers, are converted
into vinegar when exposed to the action of air. But this pro-
perty 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

THE BAVARI vN PROCESS. 31B

experimental knowledge has here led to the solution of one of the
most beautiful 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 c/iantity of
yeast is formed as a thick scum. The carbonic acid evolved
during the process attaclies itself to the particles of the yeast,
by which they become specifically lighter than the liquid
in which they are formed, and rise to its surface. Gluten, in the
act of oxidation, comes in contact with the particles of the decom-
posing sugar in the interior of the liquid. The carbonic acid
from the sugar and insoluble ferment from the gluten are dis-
engaged 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 tins gluten causes the conversion of the alcohol into acetic
acid, on account of its strong disposition to attract oxygen, and to
undergo decay. Now, it is plain, that with its separation, and
that of all substances capable of attracting oxygen, the beer
would- lose the property of becoming acid. This end is com-
pletely attained in the process of fermentation adopted in
Bavaria.

The wort, after having been treated with hops in the usual
manner, is thrown into very wide flat vessels, in which a large
surface of the liquid is exposed to the air. The fermentation is
then allowed to proceed, while the temperature of the chambers
in which the vessels are placed is never allowed to rise above
from 450 to 50° F. The fermentation lasts from three to six
weeks, and the carbonic acid evolved during its continuance is
not in large bubbles wliich burst upon the surface of the liquid,
but in small bubbles like those which escape from an acidulous
mineral water, or 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
fine viscous slime.

In order to obtain a clear conception of the great difference
Detwecn the two kinds of fermentation, it may perhaps be
sufficif Tit to recall to mind the fact, that the transformation of
gluten or of other azotized matters is a process consisting of

320 FERMENIAI'ION OF BEER

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 simultaneously disengaged. It is known with
certainty, that this formation of yeast depends upon oxygen
being appropriated by the gluten in the aci of decomposition ;
but it has not been sufficiently shown, whether this oxygen ia
derived from the water, from the sugar, or irom 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. Tiiis oxidation of the
gluten then, and the transposition of the atoms of the sugar into
alcohol and carbonic acid, are necessarily attendant on each
other, so that if the one is arrested tiie other must also cease.

Now, the yeast which rises to tlie surface of the liquid is not
the product of a complete de( ojnposition, but is oxidized gluten
still capable of undergoing a new transfojination by the transpo-
sition of its constituent elements. By virtue of this condition it
lias 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.

Yeast of this kind is oxidized gluten in a state of jruiref action j
and by virtue of this state it induces a similar transformation in
the elements of the sugar.

The yeast formed during the fermentation of Bavarian beer
is oxidized gluten in a state of decat/. The process of decompo-
sition which its constituents arr^ siiiiering, gives rise to a very
protracted putrefaction ( fer/iienfalmi) in the sugar. The inten-
sity of the action is diminisherl in so great a degree, that the
gluten which the fluid still ]H)lds 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 precipitated
gluten or yeast, causes the eremacausis of the gluten dissolved in
the wort ; oxygen gas is absorbed from the air, and all the gluter
in solution is deposited as yeast.

THE BAVARIAN PROCESS. 821

The ordinary frothy yeast may be removed from fermenting
beer by filtration, without the fermentation being thereby arrest-
ed ; but the precipitated yeast of Bavarian beer cannot be
removed without the whole process of its fermentation being in-
terrupted. The beer ceases to ferment altogether, or, if thft
temperature is raised, undergoes the ordinary fermentation.

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 temperature of
between 40*^ and 50° 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 exciting ordinary fermentation, but it produces
the other process even at a temperature of 50° F.

In wort subjected to fermentation, at a low temperature, with
this kind of yeast, the condition necessary for the transformation
of the sugar is the presence of that yeast ; but for the conversion
of gluten into ferment by a process of oxidation, something more
is required.

When the power of gluten to attract oxygen is increased by
contact with precipitated yeast in a state of decay, the unre-
strained access of ai) is the only other condition necessary for its
own conversion into the same state of decay, that is, for its oxida-
tion. We have already seen that the presence of free oxygen
and of gluten are conditions which determine the eremacausis of
alcohol and its conversion into acetic acid, but they are inca-
pable of exerting this influence at low temperatures. A low
temperature 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 un-
dergoes no such change at low temperatures, but during the oxi-
dation of the gluten in contact with it, is placed in the same
condition as the gluten itself when sulphurous acid is added to
15*

522 FERMENTATION OF BEER.

the wine in which it is contained. The oxygen of the air
unites both with the gluten and alcohol of wine not treated with
sulphurous acid ; but when this acid is present it combines with
neither of them, being 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 fermentation with the
precipitation of a mucous-like ferment consists of a simultaneous
putrefaction and decay of the same liquid. The sugar is in the
state of putrefaction, and the gluten in that of decay.

Appert's method of preserving food, and this kind of fermenta-
tion of beer, depend on the same principle.

In the fermentation of beer after this manner, all the sub-
stances capable of decay are separated from it by means of an
unrestrained access of air, while the temperature is kept suffi-
ciently low to prevent the alcohol from combining witli oxygen.
The removal 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 tem-
perature at which decay, but neither putrefaction nor fermenta-
tion, can take place. With the subsequent exclusion of the
oxygen and the completion of the decay, every cause which
could effect further decomposition of the food is removed. The
conditions for putrefaction are rendered insufficient in both
cases ; in the one, by the removrJ of the substances susceptible
of decay ; in the other, by the e?:clusicn 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 i'; 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

THE BAVARIAN PROCESS.

difficult to ascertain this, and even the analysis of these substances
cannot decide the question. Let us consider, for example, the
relations of alloxan and alloxantin* to one another. Both of
these bodies contain the same elements as gluten, although in
different proportions. Now they are known to be convertible
into each other by oxygen being absorbed in the one case, and
in the other extracted. Both arc 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 or nitric acid, it is
converted into alloxan ; into a body, therefore, which is alloxan-
tin minus 1 equivalent of hydrogen. If, on the other hand, a
stream of sulphuretted hydrogen is conducted through alloxan,
sulphur is precipitated, and alloxantin produced. It may be said
that, in the first case, hydrogen is abstracted ; in the other, added.
But it would be quite as simple an explanation, if we considered
them as oxides of the same radical ; the alloxan being regarded
as a combination of a body composed of Cg Ng Hg Og with 2
equivalents of water, and alloxantin as a combination of 3 atoms
of water with a compound consisting of Cg Nj Hg O^. The
conversion of alloxan into alloxantin would in this case result
from its eight atoms of oxygen being reduced to seven ; while
alloxan would be formed out of alloxantin, by its combining with
an additional atom of oxygen.

Now, oxides are known which combine with water, and pre-
sent the same phenomena as alloxan and alloxantin. But com-
pounds of hydrogen are not known to 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 tine-
toria) and several species of the Nerium contair- a substance
similar in many respects to gluten ; this is depos.ted 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

* Compounds obtained by the action of nitric acid on uric acid.

^24 PERMENTATION OF BEER.

latter a combination of hydrogen with the indigo blue. Dumaa
has found the same elements in both, except that the soluble
compound contained 1 equivalent of liydrogen more than the
blue.

In the same manner the soluble gluten may be considered a
compound of hydrogen, which becomes ferment by losing a cer-
tain 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 ihe insoluble condition
of gluten ; for yeast is not deposited on keeping wine, or during
the fermentation of Bavarian boer, unless oxygen lias access to
the fluid.

Now, whatever be the form in which the oxygen unites with
the gluten — whether it combines directly with it, or extracts 'a
portion of its hydrogen, forming water — the products formed in
the interior of the liquid, in consequence of the conversion of
the gluten into ferment, will still be the same. Let us suppose
that gluten is a compound jof another substance witli hydrogen,
then this hydrogen must be removed during the ordinary fermen-
tation of must and wort, by combining with oxygen, exactly as
in the conversion of alcohol into aldehyde by ereniacausis.

In both cases the atmosphere is excluded ; the oxygen cannot,
then, be derived from the air, neither can it he 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
uniting with the hydrogen of gluten, in order again to form
water. The oxygen must, therefore, be obtained from the ele-
ments of sugar, a portion of which substance must, in oixler to
the formation of ferment, undergo a different decomposition fr .m
that which produces alcohol. Hence a certain part of the sugar
will not be converted into carbonic a^ id and alcohol, but will
yield other products containing less oxygen than sugar itself con-
tains. These products, as has already been mentioned, are the
cause of the great difference in the qualities of fermented liquids,
and particularly in their quantity of alcohol.

Must and wort do not, therefore, in ordinary fermentation,
yield alcohol in proportion to the quantity of sugar which they
hbH in solution, a part of the sugar being employed in the coo-

THE BAVARIAN PROCESS. 'm

version of gluten into ferment, and not in the formation of alcohol.
But in the fermentation of Bavarian beer, all the sugar is ex-
pended in the production of alcohol ; and this is especially the
case Avhenever the transformation of the sugar is not accom-
panied by the formation of yeast.

It is quite certain that in the distilleries of brandy from potatoes.,
where no yeast is formed, or only a quantity corresponding to the
malt which has been added, the proportion of alcohol and car-
bonic acid obtained during the fermentation of the mash cor-
responds exactly to that of the carbon contained in the starch.
It is also known that the volume of carbonic 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 adopted in Bavaria
contains more alcohol, and possesses more intoxicating properties,
than that made by the ordinary method of fermentation, when
the quantities of malt used are the same. The strong taste of
the former beer is generally ascribed to its containing carbonic
acid in larger quantity, and in a state of more intimate combina-
tion ; but this opinion is erroneous. Both kinds of beer are, at
the conclusion 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 portion of the carbonic acid
evolved as corresponds to their temperature and power of solu-
tion, that is, to their volumes.

The temperature of the fluid during fermentation has a very
important influence on the quantity of alcohol generated. It has
been mentioned, that the juice of beet-roots allowed to ferment at
from 86° to 95° (30° to 35° C.) does not yield alcohol ; and that
afterwards, in the place of the sugar, mannite, a substance inca-
pable of fermentation, and containing less oxygen than sugar, is
found, together with lactic acid and mucilage. The formation
of these products diminishes in proportion as the temperature is
lower. But in vegetable juices, containing nitrogen, it is impos-
sible to fix a limit, where the transformation of the sugar is un-
disturbed by a different process of decomposition.

It is known that in the fermentation of Bavarian beer the

326 FERMENTATION OF BEER.

action of the oxygen of the air, and the low temperature, cause
complete transformation of the sugar into alcohol ; the cause
which would prevent that result, namely, the attraction of the
gluten for oxygen, by combining with which it is converted into
ferment, being exercised on oxygen derived from without.

The quantity of matters in the act of transformation is na-
turally greatest at the beginning of the fermentation of must and
wort ; and all the phenomena which accompany the process,
such as evolution of gas, and heat, are most distinct at that time.
These signs of the changes proceeding in the fluid diminish
when the greater part of the sugar has undergone decomposition ;
but they must cease entirely before the process can be regarded
as completed.

The less rapid process of decomposition which succeeds the
violent evolution of gas, continues in wine and beer until the
sugar has completely disappeared ; and hence it is observed,
that the specific gravity of the liquid diminishes during many
months. This slow 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 decomposi-
tion of the precipitated yeast ; but a complete separation of the
azotized substances dissolved in it cannot take place when air is
excluded.*

Neither alcohol alone, nor hops, noi indeed both together, pre-
serve beer from becoming acid. The better kinds of ale and
porter in England are protected from acidity, but at the loss of
the interest of an immense capital. They are placed in large
closed wooden vessels, the surfaces of which are covered with
eand. In these they are allowed to lie for several years, so that

* The great influence which a rational management of fermentation has
npon the quality of beer, is well known in several of the German states.
In the grand-duchy of Hesse, for example, a considerable premium is
oflered 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 em-
piricalTcnowledge of those conditions was obtained, the influence of which'
is rendered intelligible by theory

THE BAVARIAN PROCESS. 327

they are treated in a manner exactly similar to wine during its
ripening.

A gentle diffusion of air takes place through the pores of the
wood, but the quantity of azotized substances being very great
in 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
placod i,i s^nialier vessels, to which free access of the air is
permitted.

328 FERMENTATION ASCRIBED TO THE

CHAPTER X.

Fermentation ascribed to the Growth of Fungi and of Infuooria.

The microscopical examination of vegetable and animal mat.
ter, in the act of fermentation or putrefaction, has lately given
rise to the opinion, that these actions themselves, and the changes
suffered by the bodies subjected to them, are produced in conse-
quence of the development of fungi, or of microscopical animals,
the germs or eggs of which are supposed to be diffused every-
where, in a manner inappreciable to our senses ; they are sup-
posed to be developed when they meet with a medium fitted to
afford them nourishment.

Several philosophers have ascribed to this circumstance the
fermentation of wort, and of the juice of the grape. They assert,
that the decomposition of sugar into alcohol and carbonic acid is
effected by the contact of particles of the sugar with the growing
plants, which they view as the yeast, or ferment, without study-
ing more closely the final causes of the decomposition of the
sugar. It has been supposed that this view is opposed to the
theory detailed in the preceding pages, which described contact
as the cause of a peculiar activity or power.

In all chemical processes, and in all changes effected by
chemical affinity, we observe that contact is essential for the ex-
ercise of the acting power. Hence, chemists describe affinity as
a force distinct from other powers, because it acts only in imme-
diate contact, or at inappreciable distances. Thus contact plays
an important part in every case of combination or decomposition,
for without contact these changes would not take place. In this
sense, all substances effecting combination or decomposition are
bodies acting by contact.

In the theory of fermentation alluded to, it was not asserted
that the yeast or ferment could effect the decomposition of sugar

GROWTH OF FUNGI AND OF INFUSORIA. 329

at appreciable distances. In this respect, therefore, the two
theories are not opposed to each other. They deviate, however,
in this, that the one theory considers yeast as a body, the smallest
particles of which are in a state of motion and transposition, and
that, by virtue of this state, the particles of sugar in contact with
it are thrown into the same state of change, while the other
theory asserts, that the particles of yeast are little fungi, which
are developed from germs or seeds falling into the fermenting
liquid from the air; and that in this they grow at the expense of
the substances containing nitrogen, which are thus converted into,
and separated as, fungi. The particles of sugar in contact with
the fungi are supposed to be converted into carbonic acid and
alcohol, which, in other words, signifies, that the act of vegetation
effects a disturbance in the chemical attractions of the elements
of the sugar, in consequence of which they arrange themselves
into new compounds.

Gay-Lussac showed by experiments that the juice of grapes
expressed apart from air, under a bell-jar full of mercury, did
not er.ter into putrefaction, although it did so in the course of a
few hours when air was admitted. The same chemist also showed,
that fermentation immediately commences on the introduction of
oxygen gas, of which a quantity is absorbed equal only to the
j^th part of the volume of carbonic acid evolved during the
fermentation. It scarcely can be supposed, that the germs of
fungi exist in chlorate of potash or black oxide of manganese, out
of which the oxygen was obtained ; and hence it is difficult
to ascribe to a growing vegetation the causes of the decom-
position.

Gay-Lussac further showed, that the juice entered into fer-
mentation on being connected with the wires of a galvanic battery,
under circumstances, therefore, which quite excluded the intro-
duction of every foreign body. Hence the view, that tiie fer-
mentation of sugar IS effected by contact with growing plants,
must presuppose that living beings, plants for example, may be
formed and developed without germs or seeds- — a circumstance
in direct contradiction to all observation regarding the growth
of plants.

It is certain that sponges and fungi, growing in places from

330 FERMPLNTATION ASCRIBED TO THE

which light is quite excluded, follow laws of nutrition different
from those governing green plants ; and it cannot be doubted that
their nourishment is derived from putrefying bodies, or from the
products of their putrefaction, which paSvS directly into this kind
of plants, and obtain an organized form by the vital powers re-
siding within them. During their growth they constantly emit
carbonic acid, increasing in weight at the same time, while all
other plants, under similar circumstances, would decrease in
weight. Hence it is possible, and indeed probable, that fungi
may have the power of growing in fermenting and putrefying
substances, in as far as the products arising from the putrefaction
are adapted for their nourishment. When a quantity of fungi are
exposed to the temperature of boiling water, their vitality, and
power of germinating become completely destroyed. If they be
now kept at a proper temperature, an evolution of gas proceeds
in the mass thus treated ; they pass over into putrefaction, and,
if air be admitted, into decay ; and at last nothing remains ex-
cept their inorganic elements. The putrefiiction in this case
cannot be viev/ed as the act of the formation of organic beings,
but as the act of the passage of their elements into inorganic
compounds.

Observations of another kind — for example, that flesh and other
animal bodies may be kept for several weeks without putrefying,
if placed in a vessel containing air previously heated to redness-
— have gone far to support the opinion tliat the process of putre-
faction is effected by the growth of organic beings ; but all such
experiments are of very subordinate value in support of these
conclusions. In some experiments instituted by the author, for
the purpose of detecting quinine in the urine of a patient in the
habit of taking this medicine, he obtained the remarkable result,
that this urine kept for several weeks without passing into com-
plete putrefaction, although the urea of urine, under ordinary
circumstances, is often completely converted into carbonate of
ammonia in the space of six or eight hours. In the present case,
the urine effervesced only siightly with acids after fourteen dayss.
This seemed to give sufficient foundation for the opinion that the
quinine must be the cause of this delay in the putrefaction. But
further experiments proved tiiat common urine introduced when

GROWTH 01'* FUNGI AND OF INFUSORIA. 331

freshly drawn into perfectly pure vessels behaved in an exactly
similai manner. When a little putrefying urine was added to
the fresh urine, the putrefaction of the latter was accelerated in
a high Jegree. Wood, in wliich urine had been retained, ex-
erted this action in a very decided manner, and the white, or
yellowish- white deposit from putrefying urine (which does not
possess an organized form) effects the conversion of urea into
carbonate of ammonia in ihc course of a few hours.

Fresh flesh remains for several weeks without experiencing
appreciable change in a perfectly pure glass vessel, whether the
latter contains common air, or air previously heated to redness :
but, at the same time, it absorbs oxygen, and emits carbonic acid,
and passes into putrefaction, if the necessary quantity of water
be present, the proces^^ not being prevented or retarded by the ig-
nition of the air.

It cannot be supposed, that dung-flies, living upon animal ex-
crements, are the cause of this putrefaction ; neither can a similar
conclusion be drawn in the case of mites and maggots found so
abundantly in old cheese.

When we consider, that the intermediate products formed in
the passage of animal and vegetable matters into inorganic com-
pounds possess the power of supporting the life of certain ani-
mals and vegetables low in the scale of creation, then the only
mystery is, in what manner the germs of the fungi, or the eggs
of the infusoria, reach the place fitted for tb.eir development ; for
this being known, there is no difficulty since the discoveries of
Ehrcnberg, in conceiving this extraordinary increase. Nov/, as
it is observed that the infusoria increase in size only to a certain
point, it must hence be concluded that their nourishment, even if
only from the point at which they are to grow, passes out of their
bodies in the form of excrements, precisely as in the higher order
of ar.inihis. As in the case with all other excrements, these
nmst possess, in an eminent degree, the property of passing into
decay or putrefaction ; and this condition must at all events be
induced by contact with the original putrefying body. Hence
the increase in numbers of the infusoria must induce and acce-
lerate the process of putrefaction in the putrefying body itself.
The ultimate products of decay <ind putrefaction are carbonic

332 FERMENTATION ASCRIBED TO THE

acid, ammonia, and water. In order to comprehend the chemical
process by which this conversion is effected, it is of rnucli interest
to become acquainted with the intermediate compounds formed
by the elements. But in regard to the process itself, it is, che-
mically speaking, quite indifferent whether the first, second, or
third product, before they assume the final state, be in the form
of fungi, or of living animals (infusoria). These plants and ani-
mals are not the causes of the conversion, for they suffer after
death the same changes which finally occasion their complete
disappearance.

The enormous layers of microscopic animals in the chalk (the
siliceous infusoria) do not contain any organic matter. The lime
of their shells, and the silica of their bony coverings, were ob-
tained from the water in which they were developed. Jf this
water had been deficient in lime, or in silica, these animals could
not have been produced ; and if they had not found nourishment
in the products of the putrefaction of former species (the remains
of vvhich are found in the jnusc/ie/kalk), they would not have been
developed ; and without the co-operation of both these causes,
they could not have formed such extensive masses and layers as
they actually do.

But these animals are not the causes of the formation of the
chalk, or of the layers of flint, and as little are they the cause of
the decay and putrefaction of those substances, which yielded to
them their organic constituents. Without these animals there
might not have been chalk, but there would liave been marble, or
another limestone ; and the silica would have been deposited as
siliceous schist, or as quartz, after the evaporation of the water.
Hence it is only the form which is given to the layers by organic
life ; but the substance of these strata (chalk) is chemically in no
respect different from crystallized calcareous spar: in fact, the
same explanation of their origin might be made as that adopted in
the case of the older limestone formations.

The conversion of the constituents of an elephant into aerial
compounds is the same process, and is effected by the same causes
as those occasioning the destruction of the carcase of the micro-
Bcopical animals, which themselves obtanied their elements from

GROWTH OF FUNGI AND OF INFUSORIA. 333

extinct species of other animals. The final products are identical
in both cases.

There have been very wonderful and incomprehensible ob-
servations ma(^e on the behavior and functions of certain mi-
croscopic animals. From these observations, there seem to follow
conclusions regarding the nutrition and growth of these creatures,
quite at variance with all that we know of the process of nutrition
of the higher classes of animals.

In a treatise on the composition of the salt-springs in Hesse-
Cassel, Pfannkuch mentions a singular phenomenon, that the
slimy mass which deposits in the tub set to receive the brine per-
colating through the wells of the graduating-house, contains a gas
which is found to be pure oxygen gas. The fresh brine obtained
directly from the draw-well is quite clear, and contains 5 per
cent, of salt with gypsum and sulphuretted hydrogen in such con-
siderable quantity that it might be used as a sulphureous water.
During the summer months, a slimy transparent mass forms in
this brine, covering the bottom of the vessel containing it to the
depth of one to two inches. This matter is everywhere filled
with bubbles of gas, of a considerable size, often two or three
inches broad ; these rise to the surface, when the membrane in-
closing them is torn with a stick. The quantity of these gas-
bubbles is so great, that it would be easy to fill hundreds of
bottles with them in a short time. They are so rich in oxygen
gas, that a glowing match of wood introduced into the collected
ga.s, bursts into flame, and continues to burn with brilliancy. On
being analysed, this gas is found to consist of 51 per cent, of
oxygen, and 49 per cent, of nitrogen ; but there can be little
doubt that the gas originally consisted of pure oxygen, which be-
came mixed with the nitrogen of air by virtue of diffusion, just as
it does when confined in an animal membrane. In fact, it is
found, that when the water in the tubs is very low, the bubbles
existing in the deposit appear to be pure air, owing to the celerity
with which the diffusion has taken place (Wohler).

Wohler has subjected to microscopical examination the slimy
membranous deposit, and has shown that it consists almost en-
tirely of living and moving infusoria, principally species of Na-
vicula and Gallionella, such as occur in the paper-like formations

134 FERMENTATION ASCRIBED TO THE

of Freiberg, and in the siliceous fossil strata of Franzensbad.
The whole deposit possesses a slight greenish color, and is in.
tersected with very fine colorless fibres of confervse. After
washing and drying the deposit, a residue like paper isoMained :
and this, on being heated, gives distinct indications of ammonia,
showing that it contains nitrogen. It yields also a mass resem-
bling paper, which, on incineration, being treated with muriatic
acid, leaves behind siliceous skeletons, which preserve the shape
of the animal so completely, that it appears as if the original de-
posit itself were submitted to examination (Wohler).

These observations are of remarkable interest, for, as Wohler
asks — Whence comes the oxygen gas — from the confervse or from
the infusoria ? The quantity of oxygen being so large, and the
infusoria being in great preponderance, would lead to the con-
clusion that the former must be derived from these ; and yet this
is opposed to all analogy. The water comes out of a depth of
500 feet; ar^d its sulphuretted hydrogen shows that it comes out
of a layer of rocks containing putrefying animal matter, which,
acting upon the sulphates, produces sulphuretted hydrogen; and
in this water is formed, with the aid of solar light, a source of
oxygen gas, to all appearances more abundant than we see in the
case of green plants. Sir B. Thompson (better known as Count
Rumford) published some experiments 56 years since, which are
of such a remarkable nature, that we give them in the author's
own words. Thompson found that silk, cotton, sheep's wool,
eider-down, and other organic substances, evolve oxygen gas,
when they are freed from air by washing, and then exposed to
sun-light in a glass globe perfectly filled with water. After two
or three days, the water assumed a greenish hue, and from that
moment the evolution of gas commenced.

" One hundred and twenty grains of cotton, in a bell jar,
along with 296 cubic inches of spring water, gave out, during
the first four days, 2j C. I. of gas, containing hardly any oxy-
gen. It was not till the sixth day, when the sun was very pow-
erful, that the water suddenly became green, and gave out dur-
ing the next six days, 44^ C. I. of oxygen nearly pure. On
examining the water under the microscope, it was found to con-
lain a multitude of very minute, nearly spherical animalcules.

GROWTH OF FUNGI AND OF INFUSORIA. S35

Wherever the water was green, these animalcules were found,
insomuch that the green color seemed to be caused by them.''
After describing hi^ numerous experiments. Count Rumford
adds —

*' The phenomena now described may, perhaps, admit of ex-
planation, if we assume that the air produced in the water in the
different experiments was derived from the green matter; and
that the leaves, silk, cotton, &;c., only facilitate its disengagement
by furnishing a surface adapted to the collection and escape of
the gas-bubbles.

" These phenomena may also be explained by an assumption
favorable to the hypothesis of Priestley, namely, that the green
matter consists of plants, which, adhering to the surface of the
bodies placed in the water, there vegetate, and in consequence
give rise to the gas.

" I would willingly adopt this opinion, were it not that a most
careful and attentive examination of the green water by means
of an excellent microscope, at the period when the oxygen was
most abundantly disengaged, has convinced me, that at this pe-
riod nothing to which the name of vegetable can be given is pre-
sent. The coloring matter of the water is of an animal nature,
and is nothing else than the accumulation of an infinite number
of little moving animals." — Philosophical Transactions of the
Royal Society, Vol. Ixxvii., 1787.

In a very interesting memoir, by Messrs. August and Morren
(Transactions of the Academy of Brussels, 1841), it is shown
that water with organic substances evolves " a gas" which con-
tains 61 per cent, of oxygen ; and they conclude their trea-
tise in the following words : — " It follows from the preceding re-
rjiarks, that the phenomenon of the evolution of oxygen gas is
due to the Chlmnidomonas piihisculus (Ehrenhcrg), and to several
other green animals still lower in the scale."

The author took the opportunity of convincing himself of the
accuracy of this long-observed fact, by means of some water out
of a water-trough in his garden, the water being colored strongly
green by different kinds of infusoria. This water was freed by
means of a sieve from all particles of vegetable matter, and be-
ing placed in a jar, inverted in a porcelain vessel containing the

33(J FERMENTATION ASCRIBED TO THE

same water, was exposed for several weeks to the action of solar
light. During this time, a continued accumulation of gas took
place in the upper part of this jar ; after fourteen days ^ of the
water in the jar had been pressed out of it, and the gas, which
had taken its place, ignited a glowing match of wood, and in
all respects behaved like pure oxygen gas. It must be here ex-
pressly stated, that the water, before being exposed to the action
of solar light, was examined by one of Ploessl's best micro-
scopes, witiiout the detection of confervae or of any kind of ve-
getable matter.*

Without venturing upon any opinion on the mode of nutrition
of these animals, it is quite certain that water containing living
infusoria becomes a source of oxygen gas when exposed to' the
action of light. It is also certain, that as soon as these animals
can be detected in the water, the latter ceases to act injuriously
to plants or animals ; for it is impossible to assume that pure
oxygen gas can be evolved from water containing any decaying
or putrefying matters, for these possess the property of combin-
ing with oxygen. Now it is obvious, if we add to such water
any animal or vegetable matter in a state of decay, that this,
being in contact with oxygen, will resolve itself into the ultimate
products of oxidation in a much shorter time than if infusoria
were not present.

Thus we recognise in these animals, or perhaps on'ly in certain
classes of them, by means of the oxygen which in some way, as
yet incomprehensible, accompanies their appearance, a most wise
and wonderful provision for removing from water the substance^
hurtful to the higher classes of animals; and for substituting, iu
their stead, the food of plants (carbonic acid), and the oxygen
gas essential to the respiration of animals. They cannot be
viewed as the causes of putrefaction, or of the generation of pro-
ducts injurious to animal and vegetable life ; but they make their
appearance in order to accelerate the conversion of putrefying
organic matter into its ultimate products.

• One hundred cubic inches of water saturated with air contained, iu
the form of air, according to the experiments of Humboldt and Gsgrrl^^Uf-
•ac, not above V6 cubic inches of oxygen gas. ' "^

GROW m OF FUNGI AND OF INFUSORIA. 337

Many fungi grow without light, and in their growth and life
are characterized by all tiie phenomena which characterize ani-
mal life ; they destroy air by absorbing oxygen and evolving
carbonic acid, and, in a chemical point of view, behave like ani-
mals without motion. (See Appendix to Part II.)

In opposition to this class of beings, which can scarcely be
designated as plants, we have living creatures endowed with
motion, and with the organs which characterize animals, and
yet which behave in the light like green plants ; for while
they increase in size and number, they furnish sources of oxy-
gen when its access, in the form of air, is excluded or prevented.

16

138 DECAY OF WOODY FIBRE.

CHAPTER XI.

Decay of Woody Fibre.

The conversion of woody fibre into the substances termed hu-
mus and mould is, on account of its influence on vegetation, one
of the most remarkable processes of decomposition in nature.

Decay is not less important in another point of view ; for,
by means of its influence on dead vegetable matter, the oxy-
gen retained by plapts dLring life is again restored to the atmo-
sphere.

The decomposition of woody fibre is effected in three forms,
the results of which are diflTerent, so that it is necessary to con-
sider each separately.

The first takes place when it is in the moist condition, and
subject to free uninterrupted access of air ; the second occurs
when the air is excluded ; and the third when the wood is covered
with water, and in contact m ith putrefying organic matter.

It is known that woody fibre may be kept under water, or in
dry air, for thousands of years, without suflTering any appreci-
able change ; but that when brought into contact with air, in the
moist condition, it converts the oxygen surrounding it mto the
same volume of carbonic acid, and is itself gradually changed
into a yellowish-brown, or black matter, of a loose texture. Ac-
cording to the experiments of De Saussure, 240 parts of dry
sawdust of oak-wood convert 10 cubic inches of oxygen into the
same quantity of carbonic acid, which contains 3 parts, by weight,
of carbon ; while the weight of the sawdust is diminished by 15
parts. Hence, 12 parts, by weight, of water, are at the same
time separated from the elements of the wood.

Carbonic acid, water, and mould or humus, are therefore the
products of the decomposition of wood. We have assumed that
the water is formed by the combination of the hydrogen of the

DECAY OF WOODY FIBRE.

wood with the oxygen of the atmosphere, and that during the
process of oxidation carbon and oxygen escape from the wood
of carbonic acid.

It has already been mentioned, that pure woody fibre con-
tains carbon and the elements of water. Humus, however, is
not produced by the decay of pure woody fibre, but by that of
wood which contains foreign soluble and insoluble organic
substances, besides its essential 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 again differs from woody fibre, which is the same
in all vegetables. The difference, however, is so trivial, that it
may be altogether neglected in the consideration of the questions
which will now be brought under discussion ; besides, the quan-
tity of the foreign substances is not constant, but varies according
to the season of the year.

According to the careful analysis of Gay-Lussac and 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, contained 52-53 parts of carbon, and 47-47 parts of hy-
drogen and oxygen, in the same proportion as they are contained
in water. ^'ti^^i'A

Now it has been mentioned that moist wood acts in oxygen gas
exactly as if its carbon combined directly 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 re-
maining elements would necessarily be found in the humus, un-
changed, except in the particular of being combined with less
carbon. The final result of the action would therefore be a com-
plete disappearance of the carbon, whilst nothing but the ele-
ments of water would remain.

But when decaying wood is subjected to examination in dif-
ferent stages of decay, the remarkable result is obtained, that
the proportion of carbon in the different products augments.
Consequently, if we did not take into consideration the evolution
of carbonic acid under the influence of the air, the conversion

340 DECAY OF WOODY FIBRE.

of wood into humus might be viewed as a removal of the elementa
of water from the carbon.

The analysis of mouldered oak-wood, taken from the interioE
of the trunk of an oak, and possessing a chocolate-brown color
and the structure of wood, showed that 100 parts of it contained
53-36 parts of carbon and 46*44 parts of hydrogen and oxygen
in the same relative proportions as in water. From an examina-
tion 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, witli all other instances of the slow combustion or oxi-
dation of bodies containing a large quantity of hydrogen. Viewed
as a kind of combustion, it would indeed be a very extraordinary
process, if the carbon combined directly with the oxygen ; for
it would be a combustion in which the carbon of the burning
body augmented constantly, instead of diminishing. Hence it is
evident that it is the hydrogen which is oxidized at the expense
of the oxygen of the air ; while the carbonic acid is formed from
the elements of the wood. Carbon never combines at common
temperatures with oxygen, so as to form carbonic acid.

In whatever stage of decay wood may be, its elements must
always be capable of being i-epresented by their equivalent
numbers.

The following formulae illustrate this fact with great precision :

^3C ^2 2 ^2 2 — oak wood, according to Gay-Lussac and Th^nard.*
Cjg ^2 0 ^2 0 — hurous from oak-wood (Meyer). t
^34 "is 0,,- » „ (Dr. Will.)?

It is evident from these numbers, that for every two equiva-
lents of hydrogen oxidized, two atoms of oxygen and one of car-
bon are set free.

Under ordinary circumstances, woody fibre requires a very^
long time for its decay; but this process is of course nmuch

• The calculation from this formula gives 52"5 carbon, and 47*5 water
t The calculation gives 54 carbon, and 46 water.
X The calculation gives 56 carbon, and 44 water.

DECAY OF WOODY FIBRE. M'

accelerated by an elevated temperature and free unrestrainea
access of air. The decay, on the contrary, is much retarded by
the absence of moisture, and by the wood being surrounded with
an atmosphere of carbonic acid, which prevents the access of air
to [he decaying matters.

Sulphurous acid, and all antiseptic substances, arrest the
decay of woody fibre. It is well known that corrosive subli-
mate is employed for the purpose of protecting the timber of
ships from decay ; it is a substance which completely deprives
vegetable or animal matters, the most prone to decomposition, of
their property of entering into fermentation, putrefaction, or
decay.

But the decay of woody fibre is very much accelerated by
contact with alkalies or alkaline earths ; for these enable sub-
stances to absorb oxygen, although they 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 effect ; they greatly
retard decay.

Heavy soils, consisting of loam, retain longest the most im-
portant condition for the decay of the vegetable matter contained
in them, viz. water ; but their impermeable nature prevents
contact with the air.

In moist sandy soils, particularly such as are composed 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
snbtract from the formula C,g Hg, O,, the 22 equivalents 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 pro-
duct of the decay. In other words, 100 parts of oak, containing
52-5 parts of carbon, will leave as a residue 36-5 parts of car-

342 DECAY OF WOODY FIBRE;

Don, which must remain unchanged, since carbon does not com-
bine with oxygen at common ten: peratures.

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 carbon in the residual humus, as in
all decompositions of this kind, its attraction for the hydrogen,
which still remains in combination, also increases, until at
length the affinity of oxygen for the hydrogen is equalled by that
of the carbon for the same element.

In proportion as the decay of woody fibre advances, its pro-
perty 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 conclij-
sion can be drawn, than that the hydrogen, which analysis
shows to be present, is not contained in it in the same form as
m wood.

Decayed oak contains more carbon than fresh wood, but its
hydrogen and oxygen are in the same proportion to each other,
that is, in the proportion to form water.

We should naturally expect that the flame given out by de-
cayed wood should be more brilliant in proportion to the increase
of its carbon, but we find, on the contrary, that it burns like
tinder, exactly as it no hydrogen were present. For the pur-
poses 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
bs in the state of water ; for had it any other form, the charac-
ters we have descj-ibed would not be possessed by the decayed
wood.

If we suppose decay to proceed in a liquid containing much
carbon and hydrogen, then a compound with still more carbon
must be formed, in a manner similar to the production of the
crystalline colorless naphthalin from a gaseous compound of car-
bon and hydrogen. And if tiie compound thus formed were
itself to undergo further decay, the final result must be the sepa-
ration of carbon in a crystalline form.

Science can point to no process capable of accounting for the

DECAY OF WOODY FIBRE. 34»

origin and formation of diamonds, except the process of decay.
Diamonds cannot be produced by the action of fire ; for a high
temperature, and the 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 eremacausis. They are
found in wood (or brown) coal, and have evidently proceeded
from the decomposition of substances which were contained in
quite a different form in the living plants. They are all distin-
guished by their proportionally small quantity of hydrogen. The
acid from mellite (mellitic acid) contains precisely the same pro-
portions of carbon and oxygen as that from amber (succinic
acid) ; they differ only in the proportion of their hydrogen.
Succinic acid may be obtained by oxidation from wax and all
other solid fats.

^344 VEGETABLE MOULD.

CHAPTER XII.

Vegetable Mjuld.

The term vegetable mould, in its general signification, is
applied to a mixture of disintegrated minerals, with the remains
of animal and vegetable substances. It may be considered as
earth in which humus is contained in a state of decomposition.
Its action upon the air has been fully investigated by Ingenhouss
and De Saussure.

When moist vegetable mould is placed in a vessel full of air, it
extracts the oxygen therefrom with greater rapidity than decayed
wood, and replaces it by an equal volume of carbonic acid.
"When this carbonic acid is removed, and fresh air admitted, the
same action is repeated.

Cold water dissolves only -f o o o o'^^ of its own weight of vege-
table mould ; the solution is clear and colorless, and the residue
left on its evaporation consists of common salt with traces of sul-
phate of potash and lime and a minute quantity of organic mat-
ter, for it is slightly blackened when heated to redness. Boiling
water extracts several substances from vegetable mould, and
acquires a yellow or yellowish brown color, which is dissipated
by absorption of oxygen from the air, a black flocculent deposit
being formed. When the colored solution is evaporated, a
residue is left which becomes black on being heated to redness,
and afterwards yields carbonate of potasii when treated with
water.

A solution of caustic potash becomes black when placed in
contact with vegetable mould, and the addition of acetic acid to
the colored solution causes no precipitate or turbidity. But
dilute sulphuric acid throws down a light flocculent precipitate
of a brown or black color, from which the acid can be removed
with difliculty by means of water. When this precipitate, after

VEGETABLE MOULD. 345

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 pre-
cipitate is dried in the air. In the perfectly dry state it has en-
tirely lost its solubility in water, and even alkalies dissolve only
traces of it.

It is evident, therefore, that boiling water extracts a matter
from vegetable mould, which owes its solubility to the presence
of the alkaline salts contained in the remains of plants. This
snbstance is a product of the incomplete decay of woody fibre,
and contains a certain quantity of ammonia chemically combined.
Its composition is intermediate between woody fibre and humu^,
into which it is converted, by being exposed in a moist condition
.o the action of the air.

346 MOULDERING OF BODIES.

CHAPTER XIII.

On the Mouldering of Bodies, — Paper, Brown Coal, and Mineral Coal.

The decomposition of wood, woody fibre, and all vegetable bodies
when subjected to the action of water, and excluded from the air,
is termed mouldering.

Wcod (or brown coal) and mineral coal, are the remains of
vegetables of a former world ; their appearance and characters
show that they are products of the processes of decomposition
termed decay and putrefaction. We can easily ascertain by ana-
lysis 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 consider a peculiar change
which woody fibre suffers by means of moisture, when partially
or entirely excluded from the air.

It is known that when pure woody fibre, as linen, for example,
is placed in contact with water, considerable heat is evolved, and
the substance is converted into a soft friable mass, which has in
a great degree lost its coherence. This substance was employed
in the fabrication of paper before the use of chlorine, as an agent
for bleaching. The rags employed for this purpose were placed
in heaps ; and it was observed, that on their becoming warm a
gas was disengaged, and their weight diminished from 18 to 25
per cent.

When sawdust moistened with water is placed in a closed
vessel, carbonic acid gas is evolved in the same manner as when
air is admitted. A true putrefaction takes place, the wood as-
sumes a white color, loses its peculiar texture, and is converted
into a rotten friable matter.
. The white decayed wood found in the interior of trunks of

DECOMPOSITION OF WOOD, COAL, ETC. 34f

dead trees which have been in contact with water, is produced
in the way just mentioned.

An analysis of wood of this kind, obtained from the interior
of the trunk of an oak, yielded, after having been dried at 212*=*,

Carbon

- 4711

.

.

- 48-14

Hydrogen

- 6-31

-

-

- 6-06

Oxygen

- 45-31

-

-

- 44-43

Ashes

- 1 27

-

-

- 1-37

10000 100-00

Now, on comparing the proportions obtained from these num-
bers with the composition of oak wood, according to the analysis
of Gay-Lussac and Thenard, it is immediately perceived that a
certain quantity of carbon has been separated from the constitu-
ents of wood, whilst the hydrogen is, on the contrary, increased.
The numbers obtained by the analysis correspond very nearly to
the formula C33 Hg , 034.*

The elements of water have, therefore, along with a certain
amount of oxygen from the air, become united with the wood,
whilst carbonic acid is separated from it.

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 three
atoms of .carbonic acid deducted, the exact formula for white
mouldered wood is obtained.

Wood

/o this add 5 atoms of water

:

C,. H„ 0
- H, 0

3 atoms of oxygen -

-

0

C,. H„ 0,.

Subtract from this 3 atoms carbonic acid C ^ O ^

C,sHa7 ^4

The process of mouldering is, therefore, one of putrification
and decay, proceeding simultaneously, in which the oxygen of

• The calculation from this formula gives in 100 parts 47-9 carbon, 6-1
bjfdrogen, and 46 oxygen.

348 MOULDERING OF BODIES.

the air and the component parts of water take part. But the
composition of mouldered wood must change according as the
access of oxygen is more or less prevented. White mouldered
beech-wood yielded on analysis 47*67 carbon, 5*67, hydrogen,
and 46-68 oxygen; this corresponds to the formula C,, Hgg

o,..

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, which 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 not containing bituminous matter. This coal was sub-
jected to analysis, a piece being selected upon which the annual
circle could be counted. It was obtained from the vicinity of
Laubach ; 100 parts contained

Carbon 57'28

Hydrogen 603

Oxygen 36-] 0

Ashes 0*59

100-00

The large amount of carbon, and small quantity of oxygen,
constitute the most obvious difference between this analysis and
that of wood. It is evident that the wood which has undergone
the change into coal must have parted with a certain portion of

FORMATION OF WOOD COAL. 349

its oxygen. The proportion of these numbers is expressed by
the formula C3, H^j Oie-*

When these numbers are compared with those obtained by
the analysis of oak, it would appear that the brown coal was pro.
duced from woody fibre by the separation of one equivalent
of hydrogen, and the elements of three equivalents of carbonic
acid.

1 atom wood C36H22O22

Minus 1 atom hydrogen and 3 atoms car- \ n xj n
bonicacid . . . ^ C s W 1^ «

Wood Coal . C33H21O16

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 for.n water with this hydrogen ; conse-
quently they must all be produced by the same process of decom-
position. The excess of hydrogen is either hydrogen of the wood
remaining 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 . . . 62-60 .
Hydrogen . . 5 02

Oxygen . . . 26 52 .

Ashes . . 5 '86

63-83

4-80

25 51

5-86

10000 10000

The proportions derived from tiiese numbers correspond very
closely to the formula C,2 Hig O^, or they represent the con-
stituents of wood, from which the elements of carbonic acid,
Water, and 2 equivalents hydrogen, have been separated.

C,« H22 02 2=Wood.
Subtract C 4 H 7 Oi 3=4 atoms carbonic acid + 5 atoms of water
+2 atoms of hydrogen.

C 1 2 H 1 5 O 9 =Wood Coal from Ringkuhl.
t • The calculation givew 57-5 carbon, and 5-98 hydrogen.

350 CONVERSION OF WOOD

The formation of both these specimens of wood-coal appears
from these formulae to have taken place under circumstances
which did not entirely exclude the action of the air, and conse-
quent 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, therefore, the elements of
carbonic acid have been separated from the wood either alone,
or at the same time with a certain quantity of water. It is quite
possible that the difference in the 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 a
very similar composition. The change in this case was effected
in water, at a temperature of from 334° to 352° F. (150^ to 160°
C), and under a corresponding pressure. The ashes of the wood
amounted to 0-51 per cent.; a little less, therefore, than these of
the Laubacher coal ; but this must be ascribed to the peculiar
circumstances under which it was formed. The ashes of plants
examined by Berthier amounted always to much more than this.

The peculiar process by ^vhich the decomposition of these
extinct vegetables has been effected, namely, a disengagement
of carbonic acid from their substance, appears still to go on at
great depths in all the layers of wood- coal. At all events, it is
remarkable that springs impregnated with carbonic acid occur in
many places, in the country between the Meissner, in the electorate
of Hesse, and the Eifel, which are known to possess large layers
of wood-coal. These springs of mineral water are produced on
the spot at which they are found ; the springs of common water
meeting with carbonic acid during their ascent, and becoming
impregnated with it.

In the vicinity of the layers of wood-coal at Salzhausen
(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 CQnsidered advantageous to surround tbo

INTO BROWN OR WOOD- COAL. 3iil

sides of the spring with sandstone, and the consequence was, that
all the outlets to the carbonic acid were closed, for this gas
generally gains access to the water from the sides of the spring.
From that time to the present this valuable mineral water has
disappeared, and in its place is found a spring of common
water.

Springs of water impregnated with carbonic acid occur at
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, accord-
ing 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
formation of these acidulous springs. Their carbonic acid has
evidently not been formed either by a combustion at high or low
temperatures ; for if it were so the gas resulting from the com-
bustion would necessarily be mixed with f 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 certain quantity of carbonic acid, its com-
position indicates very plainly the manner in which it has been
produced.

The coal of the upper bed is subjected to ar incessant decay
by the action of the air, by means of which its hydrogen
is renwved in the same manner as in the decay of wood. This
is recognised by the way in which it burns, and by the formation
of carbonic acid in the mines.

The gases which are formed in mines of wood- coal, and cause
danger in their working, are not combustible or inflammable as
in mines of mineral coal ; but they consist generally of carbonio:

552 CONVERSION OF WOOD

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 possible 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 Regnault, the
composition of the combustible materials in splint coal from
Newcastle, and cannel coal from Lancashire, is expressed by the
formula C.^^ Hj, O. When this is compared with the composi-
tion of woody-fibre, it appears that these coals are formed from
its elements, by the removal of a certain quantity of carburetted
hydrogen and carbonic acid, in the form of combustible oils.
The composition of both of these coals is obtained by the subtrac-
tion of 3 atoms of carburetted hydrogen, three atoms of water,
and 9 atoms of carbonic acid from the formula of wood.

:wood
3 atoms of carburetted hydrogen C s H e
3 atoms of water . . . H 3 O 3
9 atoma of carbonic acid . C 9 O i g

Mineral coal

C12H 9021

C24 H13O

Carburetted hydrogen generally accompanies all mineral coal ;
other varieties of coal contain volatile oils which may be sepa-
rated by distillation with water. (Reichenbach.) This 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 analysis of brown coal from Ringkuhl, as well as all those of the
fame substance given in this work, have been executed in this laboratory
hy M. Khiinert, of Cassel.

INTO MINERAL COAL. 353

The iniSammable gases which stream out of clefts in the strata
of mineral coal, or in rocks of the coal formations, always con-
tain carbonic acid, according to a recent examination by Bischoff,
and also carburetted hydrogen, nitrogen, and defiant gas ; the
last of which had not been observed, until its existence in these
gases was pointed out by Bischoff. The analysis of Jire-dampf
after it had been treated with caustic potash, showed its consti-
tuents to be —

Gas from an

abandoned

Gerhard's pas-

Gas from a

n.ine near

sage near

mine near

Walleswsiller.

Luisenthal. •

Liekwege.

Vol.

FoL

FoL

Light carburetted hydrogen 91 -3^

8308

89-10

Olefiant gas - - 6-32

1-98

6-11

Nitrogen gas - - 2-32

14-94

4-79

10000 10000 100-00

The evolution of these gases proves that changes are constantly
proceeding in the coal.

It is obvious from this, that a continual removal of oxygen in
the form of carbonic acid is effected from layers of wood-coal,
in consequence of which the wood must approach gradually to
the composition of mineral coal. Hydrogen, on the contrary, is
disengaged from the constituents of mineral coal in the form of
a compound of hydro-carbon ; a complete removal of all the
hydrogen would convert coal into anthracite.

The formula C,e R^^ Ojg, which is given for wood, has been
chosen as the empirical expression ot the analysis, for the pur-
pose 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 irue constitution of woody fibre,
this cannot have the smallest influence on the account given of
the changes to which wood fibre must necessarily be subjected
in order to be converted into wood or mineral coal. The theore-
lical expression refers to the absolute quantity, the empirical
merely to the relative proportion, in which the elements of a body
are united. Whatever form the first may assume, the empirical
expression must always remain unchanged.

W4 POISONS, CONTAGIONS, MIASMS.

chapti:r XV.

On Poisons, Contagions, and Miasms.

A GREAT many chemical compounds, some derived from inorganic
nature, and others formed in animals and plants, produce pecu-
liar changes or diseases in the living animal organism. They
disturb the vital functions of individual organs ; and when their
action attains a certain degree of intensity, death is the conse-
quence.

The action of inorganic compounds, such as acids, alkalies,
metallic oxides, and salts, can in most cases be easily explained.
They either destroy the continuity of particular organs, or they
enter into combination with their substance. The action of 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 particular organs, either when heated to redness, or when in
the form of a sharp knife. Such substances are not poisons
in the limited sense of the word, for their injurious action depends
merely upon their condition.

The action of the proper inorganic poisons is owing, in most
cases, to the formation of a chemical compound by the union of
the poison with the constituents of the organ upon which it acts ;
it is owing to an exercise of a chemical affinity more powerful
than the vitality of the organ.

It is well to consider the action of inorganic substances in
general, in order to obtain a clear conception 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, wljcncc they are again eliminated

EFFECTS OF SALTS ON THE ORGANISM. 355

by the organs of secretion, either in a changed or in an un-
changed state.

Iodide of potassium, sulpho-cyanuret of potassium, ferro-
cyanuret of potassium, chlorate of potash, silicate 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 ;
l>ut 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 decom-
position. If any of these substances enter into combination with
any part of the body, the union cannot be of a permanent kind ;
for their re-appearance in the urine shows that any compounds
thus formed must have been again decomposed by the vital
processes.

Neutral citrates, acetates, and tartrates of the alkalies suffer
change in their passage through the organism. Their bases can
indeed be detected in the urine, but the acids have entirely dis-
appeared, and arc replaced by carbonic acid, which has united
with the bases. (Gilbert Blane and Wcihler.)

The conversion of these salts of organic acids into carbonates,
indicates that a considerable quantity of oxygen must have
united with their elements. In order to convert one equivalent
of acetate of potash into the carbonate of the same base, 8 equi-
A'alents 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 G
or 4 equivalents are disengaged as free carbonic acid. There is
no evidence 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
he 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 proceed-
irg in that organ ; a certain quantity of the oxygen gas inspired

856 POISONS, CONTAGIONS, MIASMS.

unites with their constituents, ami 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 process of respiration. A
part of the oxygen inspired, which usually combines with the
constituents of the blood, must, when they are present, combine
with 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 quantity, 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 ws
have described them to produce in the lungs. They participate
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 disappear.

Free mineral acids, or organic acids without volatility, and
salts of mineral acids with alkaline bases, completely arrest
decay when added to decaying matter in sufficient quantity ;
and when their quantity is small, the process of decay is pro-
tracted 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 mem-
branes, skin, cellular tissue, muscular fibre, &c. ; namely, bv
their incapability of being permeated by concentrated sa'ino
solutions. It is only when these solutions are diluted to a
certain degree with water that they are absorbed by animal
tissues.

A dry bladder remains more or less dry in saturated souN

EBTECTS OF SALTS ON THE ORGANISM. 35"

tions of common salt, nitre, ferro-cyanuret of potassium, sulpho-
cyanuret of potassium, sulphate of magnesia, chloride of potas-
sium, and sulphate of soda. These solutions run off its surface
in the same manner as water runs from a plate of glass be-
smeared with tallow.

Fresh flesh, over which salt has been strewed, is found,
after 24 hours, swimming in brine, although not a drop of water
has been added. The water has been yielded by the muscular
fibre itself, and having dissolved the salt in immediate contact
with it, and 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, animal 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 in-
troduced into the stomach, it is absorbed ; but a concentrated
saline solution, in place of being itself absorbed, extracts water
from the organ, and a violent thirst ensues. Some interchange
of water and salt takes place in the stomach ; the coats of this
viscus yield water to the solution, a part of which, having pre-
viously become sufficiently diluted, is, on the other hand, ab-
sorbed. But the greater part of the concentrated solution of salt
remains unabsorbed, and is not removed by the urinary pas-
sages ; it consequently enters the intestines and intestinal canal,
where it causes a dilution of '.he 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 property shared by all of
them ; but, besides this, they exercise a medicinal action, be«

.«M POISONS, CONTAGIONS, MIASMS.

cause every part of the organism with which they come in con-
tact absorbs a certain quantity of them.

The composition of the salts has nothing to do with their pur-
gative action ; it is quite a matter of indiiference as far as the
mere production of this action is concerned (not as to its inten-
sity), whether the base be potash or soda, or in many cases lime
.and magnesia ; and whether the acid be phosphoric, sulphuric,
nitric, or hydrochloric.

If we drink, fasting, a glass of common spring water every
ten minutes, a strong diuretic action becomes apparent, the
quantity of salts in the water being much less than that in ^hp
blood. '^

When the second glass is taken, a quantity of urine is elimi-
nated, the weight and volume of which corresponds nearly to
that of the first glass ; and by drinking twenty successive
gUxsses of water, nineteen evacuations of urine take place, the
last of which is colorless, and scarcely differs in its amount of
saline ingredients from the spring water itself.

When the same experiment is made with a water contain-
ing exactly the amount of salts as in blood ( j to 1 per cent,
of common salt for example), a separation of urine is not
effected, and it becomes almost impossible to drink more
than three glasses of such water. A sensation of fulness
in the stomach, of pressure and weight, seems to show that
water containing an equal amount of saline ingredients as blood,
requires a much longer time to be taken up by the blood-
vessels.

When the water taken contains a larger amount of salts
than that existing in blood, a more or less active purgative
action ensues. Hence, we see that three kinds of action take
place, according to the quantities of salt existing in the water.

Besides these salts, the action of which does not depend upon
their power of entering into combination with the component
parts of the organism, there is a large class of others which,
when introduced into the living body, effect changes of a very
different kind, and produce diseases or death, according to the
nature of these changes, without effecting a visible lesion of any
organs.

INORGANIC POISONS ..'550

These are the true inorganic poisons, the action of which de-
pends upon their power of forming permanent compounds with
the substance of the membranes 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 mem-
branes, 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 sub-
stances ; whilst the salts of the heavy metallic oxides are, on the
contrary, extracted from the water, for they enter into combina-
tion 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. According to all
the experiments yet made on the subject, it appears, that after
the lapse of the same time as is required for the appearance
of alkaline salts in the urine, the metallic salts above mentioned
cannot be detected in that fluid. In fact, during their passage
through the organism, they come into contact with many sub-
stances by which they are retained. By degrees, however, the
constituents of the tissues with which they have combined are
altered by the change of matter ; their nitrogen appears in the
urine, and along with it the mineral elements previously com-
bined with the organic matter, such as mercury, copper, 6zc.
When such substances enter into combination with organized
parts, the functions of those parts must be disturbed, and must
take an abnormal direction, producing morbid phenomena.

The action of corrosive sublimate and arsenious acid is very
remarkable in this respect. Corrosive sublimate and other
salts of mercury combine chiefly with albumen and albuminous
tissues.

Arsenious acid enters into a very firm combination with mem-
branes and gelatinous tissues. A piece of fresh skin, or a blad-
der which, if covered with water, liquefy in a few weeks into a

360 POISOx\S, CONTAGIONS, MIASMS.

fetid, putrid mass, retain all their properties unchanged if ar
senious acid be added to the water. The arsenious acid, combining
with these tissues, gives to them the power of resisting decay
and putrefaction. The putrefaction of flesh, or of blood, and
the fermentation of sugar, are not checked or prevented by ar-
senious acid.

It is further known that the parts of a body which come in con-
tact with these substances during poisoning, and which therefore
enter into combination with them, do not afterwards putrefy ; so
that there can be no doubt regarding the cause of their poisonous
qualities.

It is obvious that if arsenious acid and corrosive sublimate are
not prevented by the vital principle from entering into combi-
nation 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 apper-
tains to their vital condition, viz. that of suffering and effecting
transformations ; or, in other words, organic life must be de-
stroyed. If the poisoning is merely superficia); and the -quantity
of the poison so small that only individual parts of the body ca-
pable 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 poisoning are variable and
uncertain ; for cases may happen, in which no apparent indica-
tion 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 solu-
tion of this acid, every blood-globule will combine with it, that is,
will become poisoned.

The compounds of arsenic, which have not the property of en-
tering into combination with the tissues of the organism, are
without influence on life, even in large doses. Many insoluble
basic salts of arsenious acid are known not to be poisonous. The
substance called alkargen, discovered by Bunsen, has not tho

INORGANIC POISON &. 3<Jl

slightest injurious action upon the organism ; yet it contains a
very large quantity of arsenic, and approaches very closely in
composition to organic compounds.

These considerations enable us to fix with tolerable certainty
the limit at which the above substances cease to act as poisons.
For since their combination with organic matters must be regu-
lated 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.

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 mat
ters, and of thus acting as poisons. Unfortunately no other body
surpasses them in that power, and the compounds which they
form can only be broken up by affinities so energetic, that their
action is as injurious as that of the above-named poisons them-
selves. The duty of the physician consists, therefore, in his
causing those parts of the poison which may be free and still un-
combined, to enter into combination with some other body, so as
to produce a compound incapable of being decomposed or digested
in the same conditions. Hydrated peroxide of iron is an in-
valuable substance for this purpose.

When the action of arsenious acid or corrosive sublimate is
confined to the surface of an organ, those parts only are destroyed
which enter into combination with it ; an eschar is formed, and
is gradually thrown off.

Soluble salts of silver would be quite as deadly a poison as
corrosive sublimate, did not a cause exist in the human body by
which their action is prevented, 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 ani-
mal 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; ahi-
17

S62 POISONS, CONTAGIONS, MIASMS.

mal 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 othei
compounds of silver, in consequence of a part of their oxide ol
silver being reduced to the metallic state. Parts of the body
united to salts of silver no longer belong to the living organism,
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 immediately converted into chloride of silver
— a substance 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 ad-
ministered : the remaining chloride of silver is eliminated from
the body in the ordinary way.

Without solubility, or the power of being carried to every part
of the circulation, no substance possesses activity in reference to
the animal organism.

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 sul-
phuric acid. The disease csilled painter's colicis unknown in all
manufactories of white lead in which the workmen are accustomed
to take as a preservative sulphuric acid lemonade (a solution of
sugar rendered acid by sulphuric acid).

The organic substances which have combined in the living
body with metallic oxides or metallic salts, lose their property of
imbibing water and retaining it, without at the same time being
rendered incapable of permitting 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 cor.
rosive sublimate, and several of the salts of lead, possess a pecu-

INORGANIC POISONS. 3«3

liar 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 con-
traction, namely, a softening of the part of the body on which
they have acted.

Salts of oxide of copper, even when in combination with the
most powerful acids, are reduced by many 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 pois-.-ning by
copper.

With respect to some other poisons, namely, hydrocyanic acid,
and the organic bases strychnia, brucia, SfC, we are not acquainted
with facts calculated to elucidate the nature of their action. It
may, however, be presumed with much certainty, thai experi-
ments upon their mode of action on different animal sujstances
would very quickly lead to the most satisfactory conclusions re-
garding the cause of their poisonous effects.

There is a peculiar class of substances, which are generated
during certain processes of decomposition, and which act upon
the animal economy as deadly poisons, not on account of their
power of entering into combination with it, or by reason of theii*
containing a poisonous material, but -solely by virtue of their
peculiar condition.

In order to obtain 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 phenomena of fermentation, de^ay, and
putrefaction to depend.

This cause may be expressed by the following law, Lng since
proposed by La Place and Berthollet, although its tiUth with
respect to chemical phenomena hag only lately been proved. " A

MOLECULE SET IN MOTION BY ANY POWER CAN IMPART ITS OWN
MOTION TO ANOTHER MOLECULE WITH WHICH IT MAY BE IN
CONTACT."

This is a law of dynamics, the operation of which is manifest
in all cases, in which the resistance {force, ajjiinity, or cohesion)
opposed to the motion is not sufficient to overcome it.

?64 POISONS, CONTAGIONS, MIASMS.

We have seen that ferment or yeast is a body in the state of
•Jeconi position, the atoms of which, consequently, are in a state
of motion or transposition. Yeast placed in contiact with sugar
communicates to the elements of that compound the same state,
in consequence of which, the constituents of the sugar arrange
themselves into new and simpler forms, namely, into alcohol and
carbonic acid. In these new compounds the elements are united
together by stronger affinities than they were in the sugar, and
therefore under the conditions in which they were produced
further decomposition is arrested.

We know, also, that the elements of sugar assume totally dit-
ferent arrangements, when the substances which excite their
transposition are in a different state of decomposition from the
yeast just mentioned. Thus, when sugar is acted on by rennet
or putrefying vegetable juices, it is not converted into alcohol
and carbonic acid, but into lactic acid, mannite, and gum, or into
butyric acid.

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 decomposition 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 vegetable juices
is dependent on the decomposition (fermentation) of sugar ; for,
when the sugar has completely disappeared, any gluten still
remaining 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
readily passes into v, second stage of decomposition when in con-
tact with water. On account of its being in this state of further
change, yeast excites fermentation in a fresh solution of sugar ;
and if this second saccharine fluid should contain gluten (should
it be wort, for example), yeast is again generated, in consequence
of the transposition of the elements of the sugar exciting a
siniilar change in this gluten.

PUTRID POISONS. 36«

.,* After this explanation, the idea that yeast reproduces itself, as
■eeds reproduce seeds, cannot for a moment be entertained.

From the foregoing facts it follows, that a body in the act of de-
composition (it may be named the exciter), added to a mixed fluid
in which its constituents are contained, can reproduce itself in thai
fluid, exactly in the same manner as new yeast is produced
when yeast is added to saccharine liquids containing gluten.
This must be more certainly effected when the liquid acted upon
contains the body by the metamorphosis of which the exciter has
been originally formed.

It is also obvious that if the exciter be able to impart its own
state of transformation to one only of the component parts of the
mixed liquid acted upon, its own reproduction may be the conse-
quence 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 the most complex of all existing
matters.

Nature has adapted the blood for the reproduction of every
individual part of the organism ; its principal character consists
in its component parts being subordinate to every attraction.
These are in a perpetual state of change or transformation, which
is effected in the most various ways through the influence of the
different organs.

The blood does not possess the power of causing transforma-
tions ; on the contrary, its principal character consists in its readily
suffering transformations ; and no other matter can be compared
with it in this respect.

Now it is a well known fact, that when blood, cerebral sub-
stance, 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 ana-
tomical rooms frequently pass into a state of decomposition ca-
pable 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.

The poison of bad sausages belongs to this class of noxioua

366 POISONS, CONTAGIONS, MIASMS.

substances. Several hundred cases are known in which death
has occurred from the use of this kind of food. In Wurtemburg
especially tliese cases are very frequent, for there the sausages
are prepared from very various materials. Blood, liver, bacon,
brains, milk, flour, and bread, are mixed together with salt and
spices ; the mixture is then put into bladders or intestines, and
after being boiled is smoked.

When these sausages are well prepared, they may be preserved
for months, and furnish a nourishing savory food ; but when
the spices and salt are deficient, 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 undergone putrefaction, and they are found to contain free
lactic acid, or lactate of ammonia ; products seldom absent from
putrefying bodies, especially vegetable matter.

The cause of the poisonous nature of these sausages was as-
cribed 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 hydrocyanic 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 con-
stituents of the body similarly composed ; the patient becomes
much emaciated, dries to a complete mummy, and finally dies.
The carcase is stiff as if frozen, and is not subject to putrefac-
tion. During the progress of the 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 themselves acquiring
«imilar properties.

PUTRID POISONS. 3«7

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 a state of decomposition or
transposition ; a state which is destroyed by boiling water and
alcohol without the cause of the influence being imparted to those
liquids : for a state of action or power cannot be preserved in a
liquid.

Sausages, in the state here described, exercise an 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 decomposition ; and entering the blood in some way or
other, while still possessing their whole power, they impart their
peculiar action to the constituents of that fluid.

The poisonous properties of decayed sausages are not destroy-
ed by the stomach as those of the small-pox virus are. All the
substances in the body capable of putrefaction are gradually
decomposed during the course of the disease, and after death
nothing remains, except fat, tendons, bones, and a few other sub-
stances incapable of putrefying in the conditions afforded by the
body.*

* In a case of poisoning by sausages, which was communicated to me by
Herr Salzer, and which occurred r Sausenbach, near Schwab isch hall, in
May, 1842, of all the remedies that were tried sulphuretted hydrogen
water was found to possess very peculiar efficacy. All the poisoned indi-
viduals in whom it was tried early enough were saved. In those affected
by the poison there appeared hoarseness and dryness in the throat, and a
universal feeling of dryness, constipation without swelling of the abdomeri,
and without perceptible difficulty of breathing ; faintness ; dilated pupil
with impaired vision ; perfect consciousness and unimpaired motion of all
the muscles, except those supplied with nerves from the sympathetic sys-
tem, and rapid putrescence of the dead bodies. The effects were not only
dependent on the amount of poisoned sausage taken, but also very peculiar
in each case ; and in one case there was actually no effect, where a large
quantity of the same sausages had been consumed. In the treatment, the
sulphuretted hydrogen water decidedly checked the poisonous action : the
patients first perceived greater ease in swallowing ; then the general
tension and dryness diminished; the voice, which had been lost, returned;
the skin became moister, the countenance lighter, and the pressure on the
eye was relieved.

Ammonia, diluted so as to be taken as a drink, and at the same time

368 POISONS, CONTAGIONS, MIASMS.

It is impossible to mistake the modus operandi oi this poiaon,
for Colin has clearly proved that muscle, urine, cheese, cerebral
substance, and other matters, in a state of putrefaction, commu-
nicate 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, they cause its putre-
faction, 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 manner
as gluten in a state of decay or putrefaction causes a similar
transformation in a solution of sugar.

Poisons of this kind are even generated by the body itself in
particular diseases. In small-pox, plague, and syphilis, substances
of a peculiar nature 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 illustration.
But when the phenomena attending the action of each respective-
ly 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 pro^
perties. In the former case, those conditions \re afforded which

rubbed into the skin, afforded relief; but this was only temporary, and
there was no improvement observed oa continuing this treatment.

Chlorine diluted with water, and used externally and internally, produced
no improvement : on the contrary, the tension and dryness were increased
so that it soon became necessary to relinquish this treatment.

MORBID POISONS. 36d

arrest their decomposition without destroying it ; in the latter, all
tile circumstances necessary for the completioij of their deoom<
position are presented.

The temperature at which water boils, and contact with alcohol,
render such poisons inert. Acids, salts of mercury, sulphurous
acid, chlorine, iodine, bromine, aromatic substances, volatile oils,
and particularly empyreumatic oils, smoke, and a decoction of
eoffee, completely destroy their contagious properties, in some
cases combining with them or otherwise effecting their decompo-
sition. Now all these agents, without exception, retard ferment-
ation, putrefaction, and decay, and when present in sufficient
quantity, completely arrest these processes of decomposition.

A peculiar matter to which the poisonous action is duo, 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, only recognisable by our
senses through the phenomena which it produces.

In order to explain the effects of contagious matters, a peculiar
principle of life has been ascribed to them — a life similar to
that possessed by the germ of a seed, which enables it under
favorable conditions to develope and multiply itself. There cannot
be a more inaccurate image 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 fermentation, putrefaction,
or decay, and even to a piece of decaying wood, which by mere
contact with fresh wood, causes the* latter to undergo gradually
the same changes, and become decayed and mouldered,
^v. If the property possessed by a body of producing such a change
in any other substance as causes the reproduction of itself, witii
all its properties, be regarded as life, then, indeed, all the above
phenomena must be ascribed to life. But in that case they must
not be considered as the only processes due to vitality, for the
aho\e interpretation of the expression embraces the majority of
the phenomena which occur in organic chemistry. Life would,
accoi'ding to that view, be admitted to exist in every body in
which chemical forces act.

If a body A, for example oxamide (a substance scarcely solu-
17*

3t0 POISONS, CONTAGIONS, MIASMS.

ble in water, and without the slightest taste), be brought into
contact with another comiiound 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 neces-
sary for their exercising an action upon one another are present.
The elements of water unite with the constituents of oxamide,
and AMMONIA is one product formed, and oxalic acid the other,
both in exactly the proper proportions to combine and form a
neutral salt.

Here the contact of oxamide and oxalic acid induces a trans-
formation of the oxamide, which is decomposed into oxalic acid
and ammonia. The oxalic acid thus formed, as well as that
originally added, are neutralized by the ammonia — as far as that
product suffices to neutralize them ; but, of course^ as much free
oxalic acid exists after the decomposition as before it, and is 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 enters into combination whilst another portion is liberated.
In this manner a very minute quantity of oxalic acid may be
made to effect the decomposition of several hundred pounds of
oxamide ; and one grain of the acid to reproduce itself in un-
limited 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 constituents of the fluid. This transforma-
tion is not arrested until all the particles of the blood susceptible
of the decomposition have undergone the metamorphosis. We
have just seen that the contact of oxalic acid with oxamide caused
the production of fresh oxalic acid, which in its turn exercised
the same action on a new portion of oxamide. The transforma-
tion was only arrested in consequence of the quantity of oxamide
present bsin r limit-^rl. In their form both these transformationa

MORBID POISONS. 871

belong to the same class ; but although what heie takes place
exactly corresponds to the definition of life above assumed, no
unprejudiced mind would admit vitality in either process ; since
they are obviously chemical processes dependent upon the com-
mon chemical forces.

The best "definition of life involves something more than mere
reproduction, namely, the idea of an active power exercised by
VIRTUE OF A DEFINITE FORM, and production and generation in a
DEFINITE form. By chemical agency we shall some day be able
to produce the constituents of muscular fibre, skin, and hair ; but
we cannot form by their means an organized tissue, or an or-
ganic cell.

The production of organs, the co-operation of a system of or-
gans, and their power not only to produce their component parts
from the food presented to them, but to generate themselves in their
original form and with all their properties, are characters be-
longing exclusively to organic life, and constitute a form of
reproduction independent of chemical powers.

The chemical forces are subject to the invisible cause by
which this form is produced. Of the existence of this cause
itself we are made aware only by the phenomena which it pro-
duces. Its laws must be investigated just as we investigate
those of the other powers which effect motion and changes in
matter.

The chemical forces are subordinate to this cause of life, just
as they are to electricity, heat, mechanical 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 com-
plete cessation or reversal of their action.

Such an influence and no other is exercised by the vital prin-
ciple over the chemical forces ; but in every case where com-
bination 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 of motion or .change proceeds, it does not live. Its

572 POISONS, CONTAGIONS, MIASMS.

energy depends in this case on a chemical action. Light, heat,
electricity, or other influences, may increase, diminish, or arrest
this action, but they are not its efficient cause.

In this way the vital principle governs the chemical powers in
the living body, and this is particularly apparent with regard to
vegetable life. All those substances to whicli 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 possessed life, not merely the chemical forces, but this
vitality, would offer resistance to the vital force of the organism
it nourished.

The equilibrium in the chemical attractions of the constituents
of the food is disturbed by the vital principle of the plant, as we
know it may be by many other causes. But the union of its ele-
ments, 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
vita! principle.

The vital principle opposes to the continual action of the
atmospheric moisture and temperature upon the organism, a re-
sistance which is, up to a certain point, invincible. It is by the
constant neutralization 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 decom-
position or destruction, namely, the support of the process of re-
spiration, to be the means of renewing the organism, and of
resisting all the other atn^.ospheric influences, such as those of
moisture and changes of temperature.

When a chemical compound of simple constitution is introduced
into the stomach, or any other part of the organism, it must ex-
ercise 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 combinations and effect
decompositions.

THEIR MODE OF ACTION. ^

'The chemical action of such a compound is, of course, opposed
by the vital principle. The results produced depend upon the
strength of their respective actions ; either an equilibrium of both
powers is attained, a change being effected without the destruction
of the vital principle, in which case A medicinal effect is occa-
sioned ; or the acting body yields to the superior force of vitality,
that is, IT IS DIGESTED ; or, lastly, the chemical action obtains the
ascendency, and it acts as a poison.

Every substance may be considered as nutriment which loses
its former properties when acted on by the vital principle, and
does not exercise a chemical action upon the living organ.

Another class of bodies change the direction, the strength,
and intensity of the resisting force (the vital principle), and
thus exert a modifying influence upon the functions of its or-
gans. They produce a disturbance in the system, either by
their presence, or by themselves undergoing a change ; these are

MEDICAMENTS.

A third class of compounds are called poisons, when they pos-
sess t lie property of uniting with organs or with their component
parts, and when their power of effecting this is stronger than the
resistance offered by the vital principle.

The quantity of a substance and its condition must obviously
completely change the mode of its chemical action.

Increase of quantity is known to be equivalent to superior
affinity. Hence a medicament administered in excessive quan-
tity may act as a poison, and a poison in small doses as a
medicament.

Food will act as a poison, that is, it will produce disease, when
it is able to exercise a chemical action by virtue of its quantity ;
or when either its condition or its presence retards, prevents, or
arrests the motion of any organ.

A compound acts as a poison when all the parts of an organ
with which it is brought into contact enter into chemical combi-
nation with it, while it may operate as a medicine when it pro-
duces only a partial change.

No other component part of the organism can be compared to
the blood, in respect of the feeble resistance which it offers to
exterior influences. The blood is not an organ which is formed,

«74 POISONS, CONTAGIONS, MIASMS.

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 ex-
ercises an injurious influence ; even the momentary 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, and
overcomes the latter. Numerous modifications in the composition
and condition of the compounds produced from the elements of
the blood, result from the conflict of the vital force with
chemical affinity, in their incessant endeavor to overcome one
another.

All the characters of the phenomena of contagion tend to dis-
prove the existence of vitality in contagious matters. They
without doubt exercise an influence very similar to some pro-
cesses in the living organism ; but the cause of this influence is
chemical action, which is capable of being subdued by other
chemical actions, by opposed agencies.

Several of the poisons generated in the body by 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 {typhiLS
aonfagiosus ruminantium), or that of the small-pox, lose their
whole power of contagion in the stomach ; whilst that of sausa-

THEIR MODE OF ACTION. 375

ges, which has an acid reaction, retains all its frightful properties
under the same circumstances.

In the former of these cases, the free acid present in the
stomach destroys the action of the poison, the chemical properties
oii which are opposed to it ; Miiilst in the latter it strengthens, or
at all events does not offer any impediment to poisonous action.

Microscopical examination hias detected peculiar bodies resem-
bling the globules of the blood in malignant putrefying pus, in
the matter of vaccine, &c. The presence of these bodies has
given weight to the opinion, that contagion proceeds from the
development of a diseased organic life ; and these formations
have been regarded as the living seeds of disease.

This view, which does not admit of discussion, has led those
philosophers who are accustomed to search for explanations of
phenomena in forms, to consider the yeast produced by the fer-
mentation of beer as possessed of life. They have imagined it
to be composed of animals or plants, which nourish themselves
from the sugar in which they are placed, and at the same time
yield alcohol and carbonic acid as excrementitious matters.*

It would perhaps appear wonderful if bodies, possessing 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 contraiy,
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 tho eye un-
changed ; and when we recognise the globules of blood in a
liquid contagious matter, the utmost that we can thence infer is,
that those globules have taken no part in the process of decom-
position. All the phosphate of lime may be removed from bones,
leaving them transparent and flexible like leatliea*, 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 processes of de-

* Annalen der Pharmacie, Band xxix., S. 93 und 100.

376 POISONS, CONTAGIONS, MIASMS.

composition in the blood niay affect individual constituents only
of that fluid, which will become destroyed and disappear, whilst
113 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 contagions are
merely ideas and figurative representations, fitted to render the
phenomena more easy of apprehension by our senses, without
explaining them. These figurative expressions, with which we
are so willingly and easily satisfied in all sciences, are the foes
of all inquiries into the mysteries of /lature ; they are like the
fata jnorgajm, which show us deceitful views of seas, fertile fields,
and luscious fruits, but leave us languishing when we have most
need of what they promise.

It is certain that the action of contagions is the result of a pe-
culiar influence dependent on chemical forces, and in no way
connected with the vital principle. This influence is destroyed
by chemical actions, 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 sub-
stance generated from the component parts of a living body by
disease, communicates its own condition to all parts of the system
capable of entering into the same state, if no cause exist in
these parts by which the change is counteracted or destroyed.

Disease is thus excited by contagion.

The transformations produced by the disease assume 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 simi-
lar causes. When putrefying blood or yeast in the act of trans-
foimation is placed in contact with a solution of sugar, the ele-
ments of the latter substance are transposed, so as to form alcohol
and carbonic acid.

THEIR MODE OF ACTION. .^-^V

A piece of the rennet-stomach of a calf in a state of decomjK)-
sition occasions the elements of sugar to assume a different
arrangement. The sugar is converted mto lactic acid without
the addition or loss of any element. One atom of sugar of
grapes Cja H^g Oig yields two atoms of lactic acid = 2 (C,
H. O. ).

When the juice of onions or of beet-root is made to ferment at
high temperatures, lactic acid, mannite, and gum are formed.
Thus, according to the different states 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 substance with the
sugar is the cause by which its particles are made to assume new
forms and natures. The removal of that substance occasions
the cessation of the 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 tlie exciting
body reproduced ; for the conditions necessary to its reproduction
do not exist in the elements of the sugar.

Just as yeast, putrefying flesh, and the stomach of a calf in a
state of decomposition, when introduced into solutions of sugar,
effect the transformation of this substance, without being them-
selves regenerated ; in the same manner, miasms and certain
contagious matters produce diseases in the human organism, by
communicating the state of decomposition, of which they them-
selves are the subject, to certain parts of the organism, without
themselves being reproduced in their peculiar form and nature
during the pj;ogress of the decomposition.

The disease in this case is not contagious.

But, 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
lon^; 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 fiesii solution of sugar or \vort. If the sugar,

378 POISONS, CONTAGIONS, MIASMS.

however, should be first decomposed, the gluten remaining- in so ■
lution is not converted into yeast. We see, therefore, that the
reproduction of the exciting body or ferment here depends —

1. Upon the presence of that substance from which it was
originally formed ;

2. Upon the presence of a compound capable of being decom-
posed by contact with the exciting body.

If we express in the same terms the reproduction of conta-
gious 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 decom-
position of which the exciting body or contagion can be produced.
It must further be admitted, when contagion results, that the
blood contains a second constituent capable of being decom-
posed by the exciting body. It is only in consequence of the
transformation of the second constituent, that the original exciting
body can be reproduced.

A susceptibility of contagion indicates the presence of a
certain quantity of this second body in the blood of a healthy
individual. The susceptibility for the disease and its intensity
must augment according to the quantity of that body present in
the blood ; and in proportion to its diminution or disappearance,
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 reproduced from wort. Its condition of trans-
formation 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 trans-
formation or decomposition p 'oceeds more slowly than that of
the compound in th« blood, the decomposition of which it
effects.

If the transformation of the yeast generated in the fermen-
tation of wort proceeded with the same rapidity as that of the

THEIR MODE OF ACTION. S75

particles of the sugar contained in it, both would sim il-
taneously disappear when the fermentation was completed.
But yeast requires a much longer time for decomposition
than sugar, so that after the latter has completely disappeared,
there remains a much larger quantity of yeast than existed
in the fluid at the commencement of the fermentation, — yeast
which is still in a state of incessant progressive transformation,
and therefore possessed of all its peculiar properties.

The state of change or decomposition which affects one particle
of blood, is imparted to a second, a third, and at last to all tno
particles of blood in the whole body. It is communicated in
like manner to the blood of another individual, to that of a third
person, and so on — or, in other words, the disease is excited in
them also.

It is quite certain that a number of peculiar substances
exist in the blood of different men, in that of the same
man at different periods of his development, and in that of
animals.

The blood of the same individual contains, in childhood and
youth, variable quantities of substances, which are absent from
it in no other stages of growth. The susceptibility of contagion
by peculiar exciting bodies in childhood, indicates a propagation
and regeneration of the exciting bodies, in consequence of tho
transformation of certain substances present in the blood, and
in the absence of which no contagion would ensue. The form
of a disease is termed benignant, when the transformations
OF TWO constituents of the body not essential to life, are simul-
taneously completed without the other parts taking a share in
the decomposition ; it is termed malignant when they r\flrp«»t
essential organs.

It cannot be supposed that the different changes in the
substance of the existing organs, by which their constituents are
converted into fat, muscular fibre, substance of the brain and
nerves, bones, hair, &;c., and the transformation of food into
blood, can take place without the simultaneous formation of new
compounds which require to be removed from the body by the
organs of excretion.

In an adult these excretions do not vary much either in Utcir

380 POISONS, CONTAGIONS, MIASMS.

nature or quantity. The food taken is not employed in increas-
ing the size of the body, but merely for the purpose of replacing
any substances which may be consumed by the various actions
in the organism ; every motion, every manifestation of organic
properties, and every organic action being attended by a change
in the material of the body, and by the assumption of a new form
by its constituents.*

But in a child this normal condition of sustenance is accom-
panied 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, ditfused through every part of the
blood in the body of a young individual.

When the organs of secretion are in proper action, these
..ubstances 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 diseased secreting organs, and the accumulated substances
are eliminated by them. If, when thus exhaled, these sub-
stances 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 suffering the same process of
decomposition.

The production of matters of this kind, which render the body
susceptible of contagion, may be occasioned by the manner of
living, or by the nutriment taken by an individual. A super-
abundance of strong and otherwise wholesome food may produce
them, as well as a deficiency of nutriment, uncleanliness, or
even the use of decayed substances as food.

* 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 dai-k complexion were found to yield dif-
ferent odors ; the blood of animals also differed in this respect very per-
C"ptib!y from that of man.

THEIR MODE OF ACTION. 381

All these conditions for contagion must be considered as acci-
dental. Their formation and accumulation in the body may be
prevented, and they may even be removed from it without dis-
turbing its most important functions or health. Their presence
is not necessary to life.

The action, as well as the generation of the matter of conta-
gion is, according to this view, a chemical process participated
in by all substances in the living body, and by all the constitu-
ents of those organs in which the vital principle does not over-
come the chemical action. The contagion, accordingly, either
spreads itself over every part of the body, or is confined particu-
larly 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 substances, one of which
becomes completely decomposed, but communicates its own
state of transformation to the second. The second substance
thus thrown into a state of decomposition is the newly-formed
contagion.

The second substance must have been originally a con-
stituent 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 indispensable for the support of the vital func-
tions of certain principal organs, death is the consequence of
their transformation. But if the absence of the one substance
which was a constituent of the blood do not cause an immediate
cessation of the functions of the most important organs, if they
continue in their action, although in an abnormal condition,
convalescence ensues. In this case the products of the trans-
formations still existing in the blood are used for assimila-
tion, 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 disappearance.

The effects of vaccine matter indicate that an accidental con.

POISONS, CONTAGIONS, MIASMS.

stituent of the blood is destroyed by a peculiar process of decom-
position, which does not affect the other constituents of the circu-
lating fluid.

If the manner in which the precipitated yeast of Bavarian beer
acts 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 small-pox are produced from the blood. Ordinary
yeast and the virus of human small-pox, however, effect a
violent tumultuous transformation, the former in vegetable
juices, the latter in blood, in both of which fluids respectively
their constituents are contained, and they are reproduced from
these fluids with all their characteristic properties. The preci-
pitated yeast of Bavarian beer, on the other hand, acts entirely
upon the sugar of the fermenting liquid, and occasions a very
protracted 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 consequence of which this kind of yeast also is
reproduced.

The action of the virus of cow-pox is analogous to that of the
low yeast ; it communicates its own state of decomposition to a
matter in the blood, and from a second matter is itself regene-
rated, but by a totally different mode of decomposition ; the pro-
duct posse&ses the mild form, and all the properties of the lymph
of cow-pox.

The susceptibility of infection by the virus of human small-
pox must cease after vaccination, for the substance to the pre-
sence of which this susceptibility is owing has been removed
from the body by a peculiar process of decomposition artificially
excited. But this substance may be again generated in the same
individual, so that he may again become liable to contagion ; and
a second or third vaccination will again remove the peculiar sub-
stance from the system.

Chemical actions are propagated in no organs so easily as in
the lungs ; and it is well known that diseases of the lungs are,
above all others, frequent and dangerous.

THEIR MODE OF ACTION. 393

If it is assumed that chemical action and the vital principle
mutually balance each other in the blood, it must further be sup-
posed 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 do not offer 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 removal of the blood which has become arterialized. Any
disturbance in the functions of the heart, and any chemical
action from without, even though weak, occasions a change in
the process of respiration. Solid substances, also, such as dust
from vegetable, animal, or inorganic bodies, act in the same way
as they do in a saturated solution of a salt in the act of crystal-
lization, that is, they occasion a deposition of solid matters from
the blood, by which the action of the air upon the latter is altered
or prevented.

When gaseous and decomposing substances, or those which
exercise a chemical action, such as sulphuretted hydrogen and
carbonic acid, obtain access to the lungs, they meet with less
resistance in this organ than in any other. The chemical pro-
cess of slow combustion in the lungs is accelerated by all sub-
stances in a state of decay or putrefaction, by ammonia and alka-
lies ; but is retarded by empyreumatic substances, volatile oils,
and acids. Sulphuretted hydrogen produces immediate decom-
position 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 dis-
ease, it is called contagion ; but if it is the product of the decay
or putrefaction of animal and vegetable substances, or if it acts
by its chemical properties (not by the state in which it is), and

3S4 POISONS, CONTAGIONS, MIASMS.

iherefore 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 living blood.

But miasm, properly so called, causes disease without being
itself reproduced.

All the observations hitherto made upon gaseous contagious
matters prove, that they also are substances in a state of decom-
position. When vessels filled with ice are placed m air impreg-
nated with gaseous contagious matter, their outer surfaces
become covered with water containing a certain quantity of this
matter in solution. This water soon becomes turbid, and, in
common language, putrefies, or, to describe the change more
correctly, the process of decomposition of the dissolved contagious
matter is completed in the water.

All gases emitted from putrefying animal and vegetable sub-
stances in processes of disease, generally possess a peculiar
nauseous offensive smell, a circumstance which, in most cases,
proves the presence of a body in a state of decomposition, that is,
of chemical action. Smell itself may, in many cases, be con-
sidered 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 noble metals,' — those which suffer no
change when exposed to air and moisture. Arsenic, phos-
phorus, musk, the oil of linseed, lemons, turpentine, rue, and
peppermint, possess an odor only when they are in the act
of eremacausis (oxidation at common temperatures).

The odor of gaseous contagious matters is owing to the same
cause ; but it is also generally accompanied by ammonia, which
may be considered, in many cases, as the means through which
the contagious matter receives a gaseous form, just as it is the
means of causing the smell of innumerable substances of little
volatility, and of many which have no odor. (Robiquet.)*

Ammonia is very generally produced in cases of disease ; it is
always emitted in those in which contagion is generated, and is

, * Ann. de Chim. et de Phys., XV., 27.

THEIR MODE OF ACTION. 385

ail invariable product of the decomposition of animal matter.
The presence of amnionia in the air of chambers in which dis-
eased patients iie, j)articularly of those afflicted with a contagious
disease, may be readily detected ; for the moisture condensed by
ice in the manner just described, produces a white precipitate in
a solution of corrosive sublimate, just as a solution of ammonia
does. The ammoniacal salts, also, obtained by the evaporation
of rain-water after an acid has been added, when treated with
Inne 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 decomposi-
tion, and destroy the power 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 influence upon the lungs, that it may be classed
amongst the most puisunous bodies known, and should never be
employed in places in which men breathe.

Carbonic acid and sulphuretted hydrogen, which are fre-
quently evolved from the earth in cellars, mines, wells, sewers,
and other places, are amongst the most pernicious miasms. The
former may be removed from the air by alkalies ; the latter, by
burning sulphur (sulphurous acid), or by the evaporation of nitric
acid.

The characters of many organic compounds are well worthy
of the attention and study both of physiologists and pathologists,
more especially in relation to the mode of action of medicines
and poisons.

Several of such compounds are known, which to all appear-
ance are quite indifferent substances, and yet cannot be brought
into contact with one another in water without suffering a com-
plete transformation. All substances which thus suffer a mutual
decomposition, possess complex atoms ; they belong to the highest
order of chemical compounds. For example, amygdalin, a con-
stituent of bitter almonds, is a perfectly neutral body, of a slightly
bitter taste, and very easily soluble in water. But when it is
18

386 POISONS, CONTAGIONS, MIASMS.

introduced into a watery solution of synaptas (a constituent of
sweet almonds), it disappears completely without the disengage,
ment of any gas, and the water is found to contain free hydro-
cyanic acid, hydruret of benzule (oil of bitter almonds), a pecu-
liar acid and sugar, all substances of which merely the elements
existed in the amygdalin. The same decomposition is effected
when bitter almonds, which contain the same white matter as the
sweet, are rubbed into a powder and moistened with water.
Hence it happens that bitter almonds, pounded and digested in
alcohol, do not yield oil of bitter almonds containing hydrocyanic
acid, by distillation with water ; for the substance which occa-
sions the formation of those volatile substances, is dissolved by
alcohol without change, and is therefore extracted from the
pounded almonds. Pounded bitter almonds do not contain
amygdalin, after having been moistened with water, for that sub.
stance is completely decomposed when they are thus treated.

Volatile compounds cannot 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 ovei along with tJie steam. But
if, on the contrary, the seeds are trej^ted with alcohol previously
to their distillation with water, the residue does not yield a vola-
tile oil. The alcohol contains a crys-aiiinf 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 which would be regarded as absolutely indifferent
in inorganic chemistry, on account of their possessing no promi-
nent chemical characters, when placed in contact with one
another, are mutually decomposed. Their constituents arrange
themselves in a peculiar manner, so as to form new combina-
tions ; a complex atom dividing into two or more atoms of less
complex constitution, in consequence of a mere disturbance in
the attraction of their elements.

The white constituents of the almonds and mustard, which

THEIR MODE OF ACTION. 3&7

resemble coagulated albumen, must be in a peculiar state, ia
order to exert their action upon amygdalin, and upon those con.
stituents of mustard from which the volatile pungen? jil is
produced. If almonds, after being blanched and pounded, are
thrown into bailini> water, or treated with hot alcohol, with
mineral acids, or '.vjth salts of mercury, their power to effect a
decomposition in amygdalin is completely destroyed. Synaptas
is an azolized body which cannot be preserved when dissolved in
water. Its solution becomes rapidly turbid, deposits a white pre-
cipitate, and acquires the offensive smell of putrefying bodies.

It is exceedingly probable that the peculiar state of transposi-
tion into which the elements of synaptas are thrown when dis-
solved in water, may be the cause of the decomposition of amyg-
dalin, and formation 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 com in general, contain a
substance called diastase, which is formed from the gluten con-
tained, in them, and cannot be brought in contact with starch and
water without effecting a change in the starch.

When bruised malt is strewed upon warm paste of starch, 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 acquires a sweet taste, and all
the starch is found to be converted into sugar of grapes.

The elements of diastase have at the same time arranged
themselves into new combinations.

The conversion of the starch contained in food into sugar of
grapes, in diabetes mellitus, indicates that anion n^st the convStitu-
ents 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 does not oppose lesistance. The component
parts of the organ must suffer changes simultaneously with the
starcli, so that the more starch is furnished to it, the more ener-
getic and intense the disease must become ; while if only food
incapable of suffering such transformation from the same cause
.8 supplied, and the vital energy is strengthened by stimulant

388 POISONS, CONTAGIONS, MIASMS.

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 various trans-
positions, and changes of composition and properties, may be
produced in complex organic molecules, by every cause which
occasions a disturbance 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 in which they come in contact.

When copper is placed in contact with iron, a peculiar 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 temperature of
388° F. (IBQo C), the intensity and direction of the chemical
force undergo a change, and the conditions under which the ele-
ments of this compound are enabled to remain in the same form
cease to be present. The elements, therefore, arrange them-
selves in a new form ; hydrocyanic acid and water being the
results of the change.

Mechanical motion, friction, or agitation, is sufficient to cause
a new disposition of the constituents of fulminating silver and
mercury, that is, to effect another arrangement of their element?,
or to cause the production of new compounds in a liquid.

We know that electricity and heat possess a decided influence
upon the exercise of chemical affinity ; and that the attractions
of substances for one another 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 powers in the living oi^anism is dependent
upon the vital principle.

The power of elements to unite together, and to form the

THI^IR MODE OF ACTION.

peculiar compounds, which are generated in animals and vegeta-
bles, is chemical affinity ; but the cause by which they are pre -
vented 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 produced their union —
that is, after the extinction of life — most organic atoms retain
their condition, form, and nature, only by a vis inertice ; for a
great law of nature proves that matter does not possess the power
of spontaneous action. A body in motion loses its motion only
when a resistance is opposed to it : and a body at rest cannot be
put in motion, or into any action whatever, without the operation
of some exterior cause.

Tlie same numerous causes which are opposed to the forma-
tion of complex organic molecules, under ordinary circumstances,
occasion their decomposition and transformations when the only
antagonist power, the vital principle, no longer counteracts the
influence of those causes. Contact with air and the most feeble
chemical action now effect changes in the complex molecules ;
even contact with any body, the particles of which are under-
going motion or transposition, is often sufficient to destroy their
state of rest, and to disturb their statical equilibrium in the
attractions of their constituent elements. An immediate con-
sequence of this is, that they arrange themselves according to the
different degrees of their mutual attractions, and that new com-
jjounds are formed, m which chemical affinity has the ascendency^
and opposes any further change, as long as the conditions undof
which these compoun<ls w^ere formed remain unaltered.

APPENDIX TO PART II

Some potatoes, which had been wrapped in several folds of paper,
placed in a box, and kept in a dark but moderately warm place
in the laboratory, were found in March to be enveloped in a kind
of net, formed of sprouts of two lines in thickness, and 10 to 15
inches in length. On these sprouts there were several hundred
small tubers, of -f- to ^ of an inch in thickness. The sprouts and
the tubers possessed a white color, and did not exhibit any signs of
leaves. On examining the parent potatoe with a microscope, it
was found that its exterior cells were still partly filled with
granules of starch ; but the interior was quite empty, and its
substance soft and elastic. The sprouts and the cells of the
young potatoes abounded in starch.

The growth of these sprouts, and the formation of the tubers
at the expense of the constituents of the potatoes, give a good
illustration of the formation and nutrition of fungi. The organic
substance present in the potatoe obtains a new form by means of
the active power resident in the germ ; for, in this case, it cannot
be supposed that the food was extracted from the air. Now, just
as the constituents of the old potatoe entered into, and were again
found unchanged in the sprouts of the young ones, in like man-
ner animal and vegetable substances in a state of decay enter
into the fungi arising from them. Thus the ingredients of these
bodies, as the products of iheir putrefaction, pass over into the
fungi, exactly as the interior substance of the parent potatoe enters
into the sprouts and young tubers. For this conversion organic

392 APPENDIX.

power alone is sufficient, and light and other conditions of vegc
table life may be entirely excluded.

TABLE

SHOWING THE PROPORTION BETWEEN THE ENGLISH AND HESSIAH
STANDARD OF WEIGHTS AND MEASURES.

1 lb. English is equal to 0*90719 lbs. Hessian.

1 Hessian acre is equal to 26,910 English square feet.

1 En^clish square foot is equal to 1 •4S64 Hessian square feet.

1 English cubic foot contains r81218 of a Hessian cubic foot

INDEX

Absorption, by roots, 64

Of salts, 72
Acid, acetic, transformation of, 280

Formation of, 302-310

Boracic, 77

Carbonic, 3

contained in the atmo-
sphere, 14

decomposed by plants, 1 5

disintegrates rocks, 113 •

is furnished by humus, 29

is expired by animals, 16

-: is a product of decay, 299

why necessary to plants, 64

Cyanic, 84

Formic, 41
Hippuric, 49
Humic, 5

properties of, 5

contains ammonia, 6

Hydrocyanic, 266

Kinic, 71

Meconic, 71

Melanlc, 29S

Nitric, 214, 306

Phosphoric, in ashes of plants,

116
Rocellic, in plants, 65
Succinic, 343
Sulphuric, a source of sulphur,

60

retains ammonia, 181

action on soils, 185

Acids, action of, upon sugar, 278
Arrest decay, 296
Capacity of saturation, 6b
Organic, in plants, 3, 65

how formed, l38

— — essential to formation of

sugar, 137

Agave americaxa, absorbs oxy

gen, 22
Agriculture, object of, lOS

How attained, lOS

Its importance, 107

A principle in, 179

Science necessary to, 124
Air, access of, favored, 29

Ammonia in, 43

Carbonic acid in, 14

Effect of upon juices, 302

— »— on soils, 82

Improved by plants, 16

Necessary to respiration, 167

to plants, 96

Nitric acid contained in, 218
Albumen, 5S, 134
Alcohol, effect of heat on, 281

Products of its oxidation, 299

From sugar, 287
Alkalies, contained in soils, S3, 92,
111

Essential to the formation of
sugar, starch, and gum, 187

Necessity for restoring to soils,
113

Promotes decay of wood, 341

Quantity of in aluminous mine-
rals, 111

Use of ir. pk.nts, 121
Alkalins Bases, in plants, on what
their existence depends, 70

Salts in plants, sourcej* of, 114

— — contained in fertile soils,
114

• — liberaUjd from soils, by th«
action of air and of lime, 128
Alloxan, 3?4
Alloxantin, 307
Alumina, in fertile soils, 110

its influence on vegetation, llJ

394

INDEX.

Ammonia, carbonate of, in air, 43

How fixed, 181

Cause of nitrification, 309

Changes colors, 41

Condensed by charcoal, 50

Conversion of, into nitric acid,
309

Early existence of, 206

Evolved from n\anure, 51

Fixed by gypsum, 182

Contained in beet-root, 46

maple juice, 46

privies, 182

stables, 182

Furnishes nitrogen, 57

Deductions of Boussingault con-
cerning, 199

Boussingault's deductions are
erroneous, 200

Is not an essential constituent
of manure, 202

Is always of use in manure, 203

Loss from evaporation, 182

Inorganic origin of, 78

Product of decay, 42

Properties of, 41

Quantity absorbed by charcoal,
56

by decayed wood, 56

In rain-water, 44

In humus, 6

In snow-water, 44

Separated from soils by rain, 56

Solubility of, 43

Transformations of, 41

Product of disease, 384
Analysis of ashes of great import-
ance, 203
Animal, food, preservation of, 304

Life, dependent on plants, 57

processes of, 167

Matter, products of decay of, 57

essential to nitrification,

214
Animals, excrements of, how form-
ed, 50, 51

Faeces of, contain little nitrogen,
50

Liquid excrements of, rich in
nitrogen, 48

Obtain their fundamental sub-
stances from plants, 60
Annual plants, how nourished, 99

AWTHOXANTHUM ODORATVM, acid

«»,40

Anthracite, 353
Antidotes to poisons, 362
Apatite, 117, 118
Arable land, formation of, 82
Argillaceous earth. 111
Aromatics, their influence on fer-
mentation, 315
Arsenious acid, action of, 361
Ashes, analysis of various plants.
See pages 68, 143, 1.50, 203,
and Appendix to Part I., 230-
254

As a manure, 175

Of bones, 185

Of peat, 186

Of coals, 178

Of wood, 176
Assimilation of carbon, 3-27

Of carbonic acid and ammonia'
98

Of hydrogen, 35-39

Of nitrogen, 40-58
Atmosphere, ammonia in, 43

Carbonic acid in, 15

Composition is invariable, 13

Motion of, 19
Atoms, motions of, 271

Permanence in position of, 271
Azotized matter in juices of plants
102

Substances, combustion of, 307

B.
Bark of trees viewed as exeremen-
titious, 164

Of fir, analysis of its ashes, 164
Barley, analysis of its ashes, 150

Experiment oa, 22S
Basalt, analysis of, 88
Bases, alkaline in plants, on what
their existence depends, 70

Organic, 4, 71

Oxygen contaiae.I ;ii, 67

In plants, 65-81

Substitution of, 68, 70
Beans, analysis of ashes of, 143

Contain casein, 135

Nutritive power of, 134
Beech, analysis of its ashes, 248
Beer, 319

Bavarian, 319
Beet, analysis of, 12

Ammonia contained in, 46

From sandy soils, 104
BxTNiONANT diseoM, 380

INDEX.

305

Benzoic acid, formed, 48
Birch tree, ammonia in, 46
Bix>oi), analysis of its ashes, 142

Action of chemical agents upon,
374

Its feeble resistance to exterior
influences, 374

Organic salts in, 357

Its character, 367
Blossoms, when produced, 32

Increased, 98
Bones, dust of, 178, 185

Durability of, 185

Gelatine in, 186
BoRACic acid, 78
Bouquet of wines, 316
Brandy from corn, 315

Oil of, 316
Brazil, wheat in, 114
Brown Coal, 348
Buckwheat, 223

Cactus, 34

Calcium, fluoride of, 119

Chloride of, 181
Caoutchouc, in plants, 34
Carbon, assimilation of, 3, 28

Of decaying substances, seldom
affected by oxygen, 299

Derived from air, 15

In sea-water, 80

Produce of, in land, 12

in beet, 12

in straw, 12

Restored to so4, 32

Received by It^^es, 16
Carbonate of ammonia, contained
in rain-water, 44

Decomposed by gypsum, 180

Of lime in caverns and vaults,
94
Carbonic j^cid in the atmosphere,
13

Changes in the leaves, 106

Decomposed by plants, 19

Decomposes soils, 83

Emission of, at night, 26

Evaporation of, 27

Evolution from decaying b< dies,
299-302

From humus, 29

respiration, 167

woody fibre, 338

tnorease of, prevented, 16

Carbonic acid — continued.

Influerxe of light on its decom-
position, 106
Carburetted hydrogen, with

coal, 368
Caverns, stalactites in, 94
Charcoal, condenses ammonia, 56

Promotes growth of plants, 185
Chemical effects of light, 106

Processes in the nutrition of
vegetables, 2

Transformations, 265, 275
Chemistry, organic, what it is, 1
Chloride of calcium, 181

Of potassium, 72

Of sodium, its volatility, 79
Clay slate, 88, 89, 118
Clays, formation of, 90

From porphyry, 90

From felspar, 91

Potash in, 111
Clay, burned, how it acts as ma-
nure, 55, 130
Coal, formation of, 346-354

Inflammable gases from, 353

Of humus, 5

Wood or brown, 348-352
Colors of flowers, 41
Combustion at low temperatures,
300

Of decayed wood, 342

Induction of, 270, 306

Respiration, viewed as, 169

Spontaneous, 297
Concretions from horses, 118
Constituents of the blood exist in
plants, 60

The formation of, the main ob-
ject of agriculture, 53
Contagion, reproduction of, on
what dependent, 377, 378

Susceptibility to, how occasion-
ed, 373
Contagions, how produced, 376-378

Propagation of, 377-384
Contagious matters, action of, 376,
379, 383

Their effects explained, 353, 377

Life in, disproved, 353, 377

Reproduction of 353, 377-378
Copper, oxide of, in clay slate, 118
Corn, how cultivated in Italy, 114
Corn brandy, 314
Corrosive subumatk, acticsn of
361

SS6

in:)ex.

Cow-pox, action of virus of, 3S2
Cow, urine of, analysis, 169, 256, 257
Crops, rotation of, 136, 165
Cultivation, its benefits, 19

Different methods of, lOS

Object of, 109
Culture, art of, 93-122
Cyanic acid, transformation of,2S5
Cyanogen, combustion of, 310

Transformation of, 2S6

D.
Darwin on the formation of soils, 83

Descriptions of the gold ores in
Chili, 126
Death, the source of life, 58
Decay, 295

A source of ammonia, 42

Of wood, 338

And putrefaction, 273
Decomposition, 207
Diamond, its origin, 343
Diastase, 118

Contains nitrogen, 119
Disease, how excited, 355-390
Disintegration of rocks, 89

Of ores, 126
Dung of the nightingale, 262

E.
Ebony wood, oxygen and hydrogen

in, 24
Elements of plants, 3
Eremacai/sis, 295-310

Analogous'to putrefaction, 301

Arrested, 296

Definition of, 295

Necessary to nitrification, 307

Of bodies ccmUining nitrogen,

307
Of bodies destitute of nitrogen,
303
Ether, oenanthic, 316
Excrementitious matter, pro-
duction of, illustrated, 168
Excrement, animal, its chemical
nature, 169
Of the cow, horse, &c., 169,
170, 255-266
Excrements, manure in which they
are found, 169
Of animals, contain the same
amount of nitrogen, as that
present in the food, 169

Excrements — continued.

Of plants, 32

Conversion of, into humus, 33

Of man, amount of, 172, 173
Excretion, organs of, 167

Of plants, theory of, 32

F.
Fallow, 123-133
Felspar, decomposition of, 90
Analysis of, 86
Various kinds of, 86
Decomposed analysis of, 90
Ferment, 289
Fermentation, 287, 311-337

Ascribed to fungi, and infusoria,

320-337
Of Bavarian beer, 319, 325
Of beer, 311
Gay-Lussac's experiments in,

329
Of sugar, 287
Of vegetable juices, 288
Vinous, 311
Of wort, 312
Fertility of fields, how preserved,

174
Fibrin, 58, 135

Fires, plants on localities of, 116
Fir bark, analysis of its ashes, 104

Wood, analysis of its ashes, 164
Fishes in salt pans, 77
Flesh, effect of salt on, 358

Preserved under certain circum-
stances, 330, 33 J
Fluorine in ancient bones, 120
Food, effect on products of plants,
105
Of young plants, 97
Transformation and assimilation

of, 32
Knowledge of its composition

essential, 133
Undergoes combustion in the
body, 168
Formation of wood, 103
Franconia, caverns in, 94
Fruit, increased, 98
Ripening of, 38
, changes attending, 99

FUCUS GIGANTEUS, 226

Fungi, supposed to cause fermente*
tion, 326-337

INDEX.

397

Gjlseotts substances in the lungs,

effect of, 384
Gastebostetts acdxeatus, in salt-
pans, 77
Gav-Lttssac, his experiments, 327
Germination of potatoes, 99

Of grain, 102
Glue, manure from, 179
Glttten, conversion of, into yeast,
322

Decomposition of, 294

Gas from, 311
Graijv, germination of, 102
Grapes, fermentation of, 311

Juice of, differences in, 118

Potash in, 70
Grauwacke, soil from, 113
Guano, 4S, 161, 174, 258-262
Gypsum, experiment with, 53

Decomposed by carbonate of
ammonia, 182

Decomposed by salt, 63

Its influence, 53

Use of, 182

H.
Hanover tobacco, 238
Havannah tobacco, analysis of its

ashes, 238
Hay, analysis of ashes, 150, 236

Carbon in, 11
Hebsian and English weights and

measures, 392
Horse, urine of the, 169, 257, 258

Concretions in the, 119
HoRSE-DUNG, analysis of, 169, 231,

237
Hum ATE of lime, quantity received
by plants, 9

HUMIC ACID, 5

Sometimes contains ammonia,, 6
Action of, 93
Properties of, 5
Is not contained in soils, 7
Quantity received by plants, 9
Insolubility of, 93
Humus, 5

Action of, 93
Analysis of, 6
Erroneous opinions concerning,

7
Action upon oxygen, 92, 93
Coal of, 5

Humus — continued.

Conversion of woody fibre into,
338

How produced, 5

Its insolubility, 93

Properties of, 5

Sources of carbonic acid, 93

Theory of its action, 93
Hybernating animals, 100
Hydrogen, assimilation of, 35-39

Excess of in wood accounted
for, 36

Of decayed wood, 340-342

Of plants, source of, 36

Peroxide of, 270
Hyett, Mr. , on nitrate of soda, 223

Ice, bubbles of gas in, 26
lNGENHouss,,his experiments, 21
Ingredients of soil removed by

crops, 148
Inorganic constituents of plants,

64-81

L.
Lava, soil from, 110
Lead, salts of, compounds with or-
ganic matter, 360
Leaves, absorb carbonic acid, 16
Ashes of, contain alkalies, 81
Leaves of pine and fir —

Cessation of their functions, 32
Change color from absorption of

oxygen, 38
Decompose carbonic acid, 16
Their office, 16

Power of absorl)ing nutriment,
how increased, 30
Life, notion, of, 3f59
Light, absence of> its effect, 22
Chemical effects of, 105
Influences decomposition of car-
bonic acid, 105
Lime, phosphate of, 176-178
Lime, action of, 128-131
Lime-plants, 150
Lime-tree yields su^ar, 103
Limestones, hydraulic, 91, 92, 130

M.
Magnesia, phosphate of, in.

64, 65
Manure, 185-157

sue

INDEX.

Manttre — continued.

In the ashes of food burned in

the body, 148, 168
Of bones, 176, 185
The form of, important, 131
Waste of, in England, 159
Animal, yields ammonia, 169

Maple juice, ammonia from, 46
Trees, sugar of, 46

Mesotype, properties of, 87

Miasm, defined, 384

Morbid poisons, 361-375

Mosses grow luxuriantly with green
light, 107

Motion, its influence on chemical
forces, 272

MotTLD, vegetable, 344

Mouldering of bodies, 346

N.
Nitrate of soda as a manure, 223
Nitric acid from ammonia, 218

How formed 215-217
Nitrification, 307-310
Nitrogen, assimilation of, 40-57
In excrements, 169
In plants, 4

Production of, the object of ag-
riculture, 52
Transformation of bodies con-
taining, 307
Nutrition, inorganic substances re-
quisite in, 64
Superfluous, how employed, 97
Of young plants, 96

0.
Oaks, ashes of, 247

Dwarf, 30
Oak- WOOD, composition of, 247
Odor of gaseous contagious matter,

385
CEnanthic ether, 316
Organic acids, 1 40

Decomposition of, 140

Chemistry, 1
Oxygen, absorption of, at night, 21

Absorption of, by leaves, 38

by respiration, 167

Absorption of, by wood, 338-339

Action upon woody fibre, ib.

Emitted by leaves, 16

In air, 13

Consumption of, 14

In wuter. 36

Oxygen — continued.

Separated during the formation
of acids, 140

Is furnished by the decomposi-
tion of water, 36

P.
Peas 232

Ashes of, 143, 235, 250
Ashes of straw, 238
Peroxide of hydrogen, 270
Phonolite, analysis of, 88
Phosphates are constituents of

plants, 64, 67, 176, 178
Phosphoric acid in ashes of plants,

64, 67, 176, 178
Pine-tree ashes, 68, 238, 240, 242,

248,251,252
Plants absorb oxygen, 21

Analysis of ashes, 143, 235-254
Characterized by their principal

mineral ingredients, 149
Decompose carbonic acid, 26,27
Effect of, on rocks, 89
Elements of, 4
Exhalation of carbonic acid

from, 21
Functions of, 17
Improve the air, 17
Influence of gases on, 22
Mineral ingredients of, 64, 81

149
Life of, connected with that of

animals, 57
Marine, food of, 157
Milky-juiced, in barren soils, 34
Size of, proportioned to organs

of nourishment, 30
Rotation of, its advantage^ 133
Ploughing, its use, 128
Poisoning, superficial, 359

By sausages, 363
Poisons, generated by disease, 351
seq.
Inorganic, 356
Peculiar class of, 361
Rendered inert by heat, 366
Pompeii, bones from, 119
Porphyry, by disintegrating, fomui

clay, 89
Potash, in grapes, 70
Plants, 150
Replaced by soda, 70
Quantity in soils* 111

INDEX.

999

Potatoes, germination of, Appen-
dix to Part 11, 391
Purgative effect of salts explained,

354
Pus, globules in, 373
Putrefaction, 25

Communicated, 276, 363-378
Source of ammonia, 57

of carbonic acid, 57

Putrefying sausages, death from,
364
Their mode of action, 365
Substances, their effect on
wounds, 366

alkaline, 375

acid, ib.

R.
Rain, necessity for, to furnish alka-
lies to plants, 119
Want of, or excess in, producing
diseases in plants, 120
Rain-water, contains ammonia, 43
Removal of branches, effects of, 97
Rhododendron ferrugineum, 97
Ripening of fruit, 38
Roots, excrements of, 73
Rotation of crops, 133-165
Rye, 143, 232, 233

Ashes of, 239, 249

S.
Saline plants, 71
Salt, volatilization of, 79
Salts, absorption of, 73

Effects of, on the organism, 352

on fiesh, 354

on the stomach, ib.

Organic, in the blood, 353
Passage of, through th« lungs,
352
Salt-works, loss in, 79
Sand, disintegrates when exposed
to the action of carbonic acid,
87
Saturation, capacity of, 66
Sausages, poisonous, 364
SAU88URE, his experiments on air,
15
On the mineral ingredients of
plants, 64, 242-248
SciBNCK not opposed to practice,

124
SxA> WATER, analysis of, 79

Sea-water — eontintted.

Contains carbon, 80

Contains ammonia, 80
Silica, properties of, 84, 86
Silicates, disintegration of, 155
Silver, salts, poisonous effects of,
359

SiNAPIS ALBA, 387

Size of plants proportioned to or™

gans of nourishment, 30
Snow-water, ammonia in, 43
Soda, may replace potash, 70
Soils, advantages of loosening, 12 #

Analyses of, 263

Exhaustion of, 113

Ferruginous, improved, 95

FeTtiie, of Vesuvius, 131

Formation of, 82-92

From lava, 131

Imbibe ammonia, 51

Physical properties of, 148

Important, 152

Exhaustion of, 1 16
Stagnant water, effect of, 95
Stalactites in caverns, 93
Starch, accumulation of, in plants,
98

Composition of, 37

Development of plants influ-
enced by, 99

Product of, the life of plants, 21

In willows, 98
Straw, analysis of, 12

Of rye, 249
Struve, experiments of, 113
Substitution of bases, 66
Succinic acid, 343
Sugar, formed from acids, 137

Composition of, 287

Carbon in sugar, 12

Contained in the maple tree, 45

In Clerodendron fragrans, 103

Development of plants, influ-
ence on, 99

Fermentation of, 287

In beet-roots, 45

Metamorphosis of, 288

Product of, the life of plants, 21

Transformation of, 275, 8eq.

When produced, 31
Sulphate of ammonia, well adapt
ed to furnish plants with sul
phur, 61
Suij>HATX0 in water of ipriogB, 61

400

INDEX.

iSuiiPHATEs — continued.

Yield sulphur, G2
Sui-PHUR, crystallized, dimorphous,

proportion of, to nitrogen in

plants, 62
Source of, in plants, 58
Sulphuric acid, action of, on soils,

187
Sulphurous acid arrests decay, 341
Sywaptas, 388

Tables of Hessian and English

weigfhts and nMasures, 392
Tannic acid, 36
Tartaric acid, 36

Converted into sugar, 37

In wine, 298
Teltow parsnip, 30
Thenard, his experiments on yeast,

290
Tin, action on nitric acid, 268
Tobacco juice, contains ammonia, 47

Nitric acid, 48

In Virginia, 113
Transformation, by heat, 280

Chemical, 265

Of acetic acid, 280

Of carbonic acid, 106

Of meconic acid, 2S0

Of bodies containing nitrogen,
- 282

Of bodies destitute of nitrogen,
280

Results of, 31

Of wood, 281

Of cyanic acid, 284

Of cyanogen, 285

Of gluten, 311
Transplantation, effect of, 97
Trees, diseases of, 102

Require alkalies, 115

U.
Ulmin, 5
Urea, converted into carbonate of

ammonia, 48
Urine, contains nitrogen, 48

Its use as manure, 47

Of men, 173

Of horses, 169

Human, analysis of, 173

Of cows, 169

V.

Vaccination, its effect, 382

Vegetable albumen, 48

Mould, always contains carbon-
ate of ammonia, 96

Vegetation, tropical, 161

Vesuvius, fertile soil of, 112

Vines, juice of, yields ammonia, 46

Vinous fermentation, 311

Virginia, early products of its soils,
114

Virus, of small pox, 382
Vaccine, 382

Vital principle, how balanced in
the blood, 371

W.
Water, carbonic acid of, absorbed,
17

Decomposes rocks, 113

Composition of, 36

Dissolves mould, 344

Plants, their action upon, 26

Rain, contains ammonia, 43

required by gypsum, 55

Salt, analysis of, 79
Waveute, 117
Wheat, exhausts, 114

Gluten of, 46

Why it does not thrive on cer-
tain soils, 115

In Virginia, 114

Red, 143

White, 182
Willows, growth of, 98
Wine, effect of gluten upon, 318

Fermentation of, 317

Properties of, 318

Substances in, 313

Taste and smell, 314

Varieties of, ib.
WoAD, decomposition of, 294
Wood, decayed, combustion of, 342

Absorbs ammonia, 56

Analysis of, 24

Conversion of, into humus, 339

Decay of, 338

Requires air, t6.

Decomposition of, 266, 295

Effect of moisture and air on, 338

Elements of, 339

Formation of, 102

Source of its carbon, 12

Transformation of, 981

INDEX 401

Wood-coal, how produced, 348

Analysis of, 348, 349 Y.

Woody fibre, changes in» 338 Yixbt, 290

Composition of, 339 Destro^jred, 313

Decomposition of, 338 Experiments on, 290

Difference between it and wood, Formed, 312

24 Its mode of action, 293

Formation of, 20 Its production, 338 »

Moist evolves carbonic acid, 338 Two kinds of, 320, #eg.

Mould from, 343
Wort, fermentation of, 319 Z.

Wounds, effect of putrefying sab- Zboutx, analysis of, 87
stances on, 366

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