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ROCKS AND SOILS:

THEIR ORIGIN, COMPOSITION
AND CHARACTERISTICS;

CHEMICAL, GEOLOGICAL and AGRICULTURAL.

BY

HORACE EDWARD STOCKBRIDGE, Ph.D.,

President of Agricultural College of North Dakota.

SECOND EDITION— REVISED AND ENLARGED.
FIRST THOUSAND.

NEW YORK:

JOHN WILEY & SONS,

53 East Tenth Street.

1895.

Copyright, 1888,
By John Wiley & Sons.

Dbummond & Nku,

Ferris Bros,,

Electrotypers. Ertnters,

1 to - Hu^nie Street. 338 p^^,, ^^^^^

'"-•''' Y"'"''- New York.

PREFACE.

Five years ago I was requested to prepare a course of in-
struction in chemical geology for students in one of the
American agricultural colleges. Since then it has been my
privilege to deliver a series of lectures on the subject to sij<
consecutive classes, first at the Massachusetts Agricultural Col-
lege, and later here in the Imperial College of Agriculture.
When I entered into an engagement with the Japanese Govern-
ment, the continuation of such instruction was stipulated as a
part of my duty.

These facts account for the compilation of the material here
gathered. The reasons for now presenting the results to a larger
audience are chiefly these : As the work has progressed, my
students have repeatedly requested the preservation of the
lectures in a more permanent and accessible form ; while the
magnitude of the field from which I have garnered, and the ex-
tremely scattered condition of the literature to which access
was found necessary, have convinced me of the desirability of
attempting to bring the materials together in a more readily
accessible form,— an attempt not previously made, I believe.
Hence the book must present some features peculiar to itself,
and may, therefore, reasonably seek a favorable, or at least con-
siderate, reception by those in whose interests it has been pre-
pared.

The nature of the work is such that I have no claim for the
presentation of new material ; I have neither theories nor opin-
ions of my own to force upon the public. Such personal views
as are offered are only expressed where such a course was
deemed essential to a clear presentation of the facts recorded.
I have sought to grive a lucid and concise statement of such

VI PREFACE.

facts as are recognized as facts in the light of the most recent
and authoritative interpretation of the phenomena considered.

With this end in view, every available source of information
has been utilized. A list of works of reference for those who
desire further details has been placed in the Appendix. The
nature of the work, its origin and scope, preclude the possibility
of individual reference to each source of information; but
V, hcre\'er facts recorded seem to make such authority desirable,
reference is made to the originals. Further than this, I desire
to make acknowledgments to all whose labors have been found
of assistance, and especially to express my indebtedness to the
w'orks of Credner, Dana, Johnson, Gohren, and Mayer.

My location so far from the place of publication has rendered
personal supervision of proofs impossible ; but I have every
confidence in the ability and fidelity of the two friends to
whom this task has been confided ; and to them, Dr. Charles
Wellington of the Massachusetts Agricultural College, and Mr.
Henry G. K. Heath of New York City, as well as to the pub-
lishers, my thanks are due and heartily expressed.

I have hoped that the book might be especially acceptable
to students and farmers, and with this hope the labor has been
performed. Should my professional friends, however, find it
a convenient and reliable compend of the subjects treated, my
gratification will be proportionally increased.

H. E. Stockbridge.

Sapporo, Japan, March, 1888.

PREFACE TO THE SECOND EDITION.

More than a year has elapsed since the original edition of
this work was exhausted. During this interval publishers and
author have been frequently importuned for the issue of a
new edition, but other duties and the delays incident upon the
collecting of new material have prevented an earlier comple-
tion of the work.

The author would have preferred to somewhat change the
scope of the present edition by rewriting and combining Parts
I and II and making them more specifically introductory to
the subject-matter of Part III, that the work might be still
more distinctly devoted to SOILS. For the present, however,
this plan was not feasible, though the hope of its accomplish-
ment is not relinquished.

The changes introduced are chiefly the correcting of errors
incident upon the conditions under which the publication was
originally issued. A few changes of statement, necessitated by
the progress of the past seven years, have been made.

A new Chapter on the USE OF THE SoiL has been added to
Part III. In this chapter it is believed the latest develop-
ments of science as related to soils are recorded and the most
recent applications of the principles involved are elaborated.
Several additional tables have been included in the Appendix
which it is believed will add materially to the value of tne
work.

These tables are, in their present arrangement, new, part of
them are original ; but the author desires to acknowledge
special indebtedness to the compilations published in the

Vlll PREFACE TO THE SECOND EDITION.

" Handbook of Experiment Station Work " issued by the
United States Department of Agriculture. He is extremely
glad that the accumulation of American data has enabled him
to make this new portion of the work more distinctly Ameri-
can ; it should be borne in mind, however, that the original
edition was not written in America nor entirely for Americans.
In its present form it is not only hoped that the book will
be accorded the favor granted the first edition, but that the
changes and additions will increase the practical utility of the
work and bring it into still more intimate and friendly rela-
tions to progressive farmers.

H. E. Stockbridge.

New York, February, 1895.

CONTENTS.

. Part First.
ROCK HISTORY.
INTRODUCTION.

PAGE

Rock and Soil, r

Mutual relations.— Both mere variations in form of one and
the same material. — Geology, the study of rocks. — Different
forms of rocks, stratified, unstratified. — Rock strata, dif-
ferent kinds of. — Fault. Flexure, Denudation. — Order of ar-
rangement of strata. — Historical Geology. — Chemical Geology.
— Agricultural Chemical Geology. — Authentic history, dawn
of. — Kant's hypothesis, world-formation, different phases of. —
Fundamental formation. — Sedimentary rocks, a secondary for-
mation.— Original rocks not accessible, probable composition
of. — Divisions of geological time.

CHAPTER I.

Arch.ean Time, • . 6

First evidences of life. — Primary Gneiss, or Laure7itian Forma/wti,
distribution of. — Crystallinic Slate, or Huronian Period. — Rocks,
distribution. — Agricultural and economical characteristics.

CHAPTER II.

Paleozoic Time lo

Divisions of. — First indisputable evidences of life. — Silurian For-
mation, Age of Invertebrates, divisions of. — Rocks, distribution.
Agricultural and ecomical features. — Anthracite coal. — Close of
the age. — Dc7'onian Formation, Age of Fishes, life of. — Rocks. —
Old red sandstone. — Distribution. — Agricultural and economical
features. — Petroleum. — Iron. — Phenomena closing the age. —
Carboniferous Age, coal-formation. — Sub-carboniferous. — Silu-
rian scorpions. — Rocks, distribution. — Depth of coal. — Coal-mea-

X cox TENTS.

PAGB

sures. — Millstone grit. — Industrial accompaniments of the coal.
— Mineral deposits. — Origin and process of coal-formation. —
Agricultural features. — Close of the age. — Per/itian Formation,
origin of name. — Rocks. — New red sandstone. — Zechstein. —
Distribution. — Characteristic phenomena, valley formation. —
Agricultural and economical features. — Rock salt. — Close of the
age.

CHAPTER III.

Mesozoic Time, Age of Reptiles 27

Divisions. — Mediaeval time of geologic history. — Triassic Forma-
tion.— Rocks, "bonebed." — Eruptive phenomena. — Fossil foot-
prints.— Similarity between birds and reptiles. — Agricultural and
economical features. — Climate and life. — Jurassic Formation,
life of. — Rocks. — Climate, distribution. — Agricultural and eco-
nomical features. — Eruptive phenomena, closing period. — Creta-
ceous Formation, or chalk-formation, life. — Distribution. — Divi-
sions.— Agricultural and economical features. — Chalk, origin of.
— Flint. — Climate, consequent changes in life.

CHAPTER IV.

Cenozoic Time, 37

Recent Period, divisions. — Tertiary Formation. — Characteristics. —
Survival of the fittest. — Life. — Subdivisions. — Rocks, distribu-
tion.— Closing phenomena of the age. — Agricultural and eco-
nomical features,^ph')sph;ite deposits. — Coprolites. — Quater?iary
Formation, Age of M //.—Divisions of. — Glacial Period, drift,
characteristic phenomena. — Origin. — Iceberg theory. — Glacial
theory, proved by phenomena of present occurrence. — Rocks. —
Life. — Distribution. — Man. — Stone Age. — Lake dwellers. — Pro-
gressive stages of man's development. — Bronze Age. — Alluvian
Formation. — Recent. — Character of deposits. — Agricultural as-
pects.

Part Second.
ROCK COMPOSITION AND DECOMPOSITION.

CHAPTER I.

Classification and Composition of Rocks, . . .^. . 59
Rock and Soil, one to be studied through the other. — Rock-classifi-
cation.— Crystalline rocks, acidic and basic, non-crystalline
rocks. — Rock-composition.

CONTENTS. XI

CHAPTER II.

PAGE

Disintegration through Internal Forces. ... 70
Earth -development.— Dynamical Geology. — Volcanoes, forms of. —
Causes of eruption. — Results of eruption. — Rock-transformation
and decomposition. — Thermal Waicj-s, origin of. — Geysers. —
Rock-decomposition. — Coniractioti of the Earth's Surface. —
Change of level. — Elevation, depression. — Changes of former
times. — Mountain-formation. — Flexibility of rock-masses. — Con-
tinent-formation.— Earthquakes, kind, characteristics. — Causes.
— Charleston, South Carolina. — Earthquakes and geological
structures. — Earthquake observation. — Rock-nietamorphism. —
Pressure, heat, moisture. — Hydro-chemical process. — Pseudo-
morphism.

CHAPTER III.

Rock Disintegration through External Forces, . . 93
Changes of Temperature. — Action of Water, mechanical activity of
water. — Deposits of running waters. — Delta- formation. — Glacier-
action. — Oceans. — Chemical action of water. — Carbonic-acid
waters. — Acti'oti of the Air. — Action of Organic Life. — Animals.
Reduction through decomposition of plants. — Chemical action
of roots. — Action of decomposing organisms.

CHAPTER IV.

Products of Rock Disintegration 114

Weathering.— T\mQ required. — Products of weathering. — Crystal-
line rocks. — Non-crystalline rocks.

Part Third.

SOILS.
CHAPTER I.

Origin and Composition of Soils 123

Rocks become soil with the addition of organic matter. — Plants as
Sources of this Orga7iic Matter. — Humus. — Conditions essential
to organic decomposition. — Animals as Sources of Orgastic
Matter. — Burrowing animals. — Earth-worms. — Secretion of
acids by worms. — Composition of the Soil. — Atmospheric ingredi-
ents.— Action of humus compounds on mineral matter. — Nitro-
gen. -Ammonia. — Conversion of combined organic nitrogen

Xll CONTENTS.

PAGE

into ammonia. — Nitrification. — Atmospheric nitrogen and nitrili-
cation. — Other atmospheric ingredients of soils. — Non-atmos-
pheric ingredients of soils.

CHAPTER II.

Classification and Characteristics of the Soil, . . 152
Distinctions based on methods of formation. — Kinds of soil. —
Characteristics. — Distz7ictions based on Physical Characteristus.
— Other distinctions. — Soil-analysis. — Physico-chemical Charac-
teristics of Soils. — Physical weight. — Specific gravity. — Struc-
ture.— Color. — Behavior toward Water. — Imbibition. — Permea-
bility.— Evaporation. — Plant-exhalation. — Absorption. — Solu-
tion by water.

CHAPTER III.

Characteristics of Soils — [Contimced) 166

Soil and heat. — Color. — Specific heat. — Moisture as affecting heat.
— Radiation. — Dew. — Difference between temperature of soil
and air. — Experiments on deposition of dew on soil and plant. —
Causes and conditions of dew-deposition. — Conditions modify-
ing soil-temperatures. — Soil and Electricity. — Soils and Gases.
CHAPTER IV.

The Soil as Related to the Production of Plants, . 194
Office of the soil. — Soil as Habitat of Plants.^-Soi\ as feeder and
storehouse of the plant.— Extraction and assimilation of plant-
food. — Assimilation of atmospheric food. — Organic ingredients
of vegetation. — Formation of carbohydrates. — Albuminoids.—
Assimilation of soil-food. — Methods of soil-solution. — Mineral
ingredients indispensable to plants. — Proper concentration of
plant-fooii. — .Absorptive power of soils. — Results of absorption.
— Soil-exhaustion. — Maintenance of soil-fertility.
CHAPTER V.

Use of the Soil, 215

l^urpose of the soil. — Preparing the Soil for the Crop. — Cultiva-
tion.— Implements and methods. — Pulverization. — Fineness
of division. — Aeration. — Supply of plant-food. — What and
when apply. — Form of supply. — Cost of supply. — Manures.
— Value of. — Physical action of. — Time and method of applica-
tion.— Loss in value of manures and fertilizers. — Amelioration
of the soil. — The Crop, as affected by physical properties of
soils. — Crop and moisture. — Methods of conserving moisture. —
Chemical conditions influencing soil waters. — Alkali soils. — In-
fluence of moisture on soil temperatures. — Effects of Cropping.
— Soil renovation. — Rotation. — Inoculation. — Renovation by
fertilization. — Crop-producing power.

Appendix, . . ^ 249

Index, 275

ROCKS AND SOILS.

PART I.

INTRODUCTION.

The solid earth on which we hve and from which we draw
sustenance consists of material existing in two essentially dif-
ferent physical conditions as rock and as soil ; one being more
usually the surface decked with verdure, teeming with animal
and vegetable life, and supplying us with all the requisites of
happy existence ; the other forming the unyielding foundation
on which the great superstructure rests, here and there pro-
truding above the surface as cliffs of sea-shore, rocky ledges,
or summits of hills and mountains.

There is a constant change of condition between these two
forms, all soils having been produced by the disintegration of
rock, and being capable of reconversion to the former condition
again ; and both forms are equal!}- recognized as geologically
forming mere variations in form of one material considered as
rock, consolidation being regarded as a mere accident of cir-
cumstance.

Geology is pre-eminently the study of rocks, their forma-
tion, transformation, and present distribution.

These rocks most frequently repose in beds of more or less
nearly parallel layers known as strata, the rocks thus situated
having been deposited from material held suspended in water,
and being known as stratified rock.

The position of strata, though originally horizontal, may now
be any degree of variation from this condition through the

2 JiOCA'S AND SOILS.

contortions of nature to which the pHable strata have been
subjected.

The tliickness of an individual layer or stratum may vary
from a few inches to thousands of feet ; and the total thick-
ness of all known strata would be not more than twenty miles.

Below these deposited rocks exist iDist ratified crystalline
rocks. Surface rocks may, however, be unstratified, and exist
as solid mountains of granite or other crystalline rock, wholly
free from all traces of stratification.

Dislocations of strata have occurred to most rock deposits,
whereby the original horizontal position has been changed, a

fact of the great-
est importance in

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Fig. I.— Dislocations of Strata. part ot the CUtU'e

series of rock strata is thus made accessible than would other-
wise be possible.

Should these strata have become fractured and the layers
displaced, the displacement is known as a fault. Should no
actual fracture have occurred, a fold or flexure is the result ;
and if the upper surface or apex of the fold should be worn
away a series of dips becomes exposed, the result being known
as denudation.

It frequently happens that a series of strata become flexed,
and that on top of the folds formed new strata of more recent
origin may be deposited, producing the phenomenon of uncon-
formability of strata.

The order of arrangement of strata is of the utmost impor-
tance, as it offers the only key with which to decipher these
records of earth-history, since the strata were not laid down at
one time, but form distinct leaves, each leaf recording the geo-
logical events of but a brief span of time. The chronological
arrangement of these leaves is, therefore, the only means by
which a logical presentation of all the facts of a given era or
formation, and ultimately of all formations or eras, may be
hoped for.

Fig. 2.— Strata aud Joints.

m-- ni;\,!j

(To face page 2.)

IN TROD UC TION. 3

Historical Geology is devoted to the study of these records of
earth-history. Chemical Geology deals with the phenomena of
rock-composition and rock-decomposition.

The original rock-crust of the Earth has been constantly sub-
jected to disintegrating influences whose ultimate product is a
geological formation, no longer solid rock, but more or less
arable soil. The reactions accompanying this transformation
of rock into soil form the proper sphere of Agricultural Cheini-
cal Geology.

With a province extending through all the phases of geo-
logic time, this department of geological science is really a
chemical history of the inanimate, inorganic world. A brief
outline of this history as recorded in the rocks themselves is,
therefore, essential to an understanding of the phenomena to
be considered.

Authentic geological history begins only with the organized
existence of the world, whose rock-formations are the records
of its progress; but an earlier and prehistoric existence was
necessitated — a period the essential conditions of which are
none the less fact because incapable of ocular demonstration.

Kant's Hypothesis, the so-called "jiebular theory,'' most
satisfactorily and logically enunciates the occurrences of this
world-formation epoch in cosmic history: — The entire planetary
system, of which our Earth forms to-day so infinitesimal a part,
had its origin in a misty, nebulous mass rotating from west to
east, in a state of extraordinarily high temperature, about its
own nucleus, our present sun. The outermost limit of this
system reached far beyond the present orbit of the most dis-
tant planet. Through the radiation of heat into space re-
sulted a cooling of this vapory mass ; and the accompanying
contraction and concentration were followed, of necessity, by
an increased rapidity of rotation. So soon as the rapidity of
this rotation reached and passed a certain limit, by the laws of
centrifugal force there resulted the formation of equatorial
rings, which, through unequal conditions and unequal cooling,
became broken, each individual segment forming, in time, an
independent nebulous sphere still rotating ever from west to
east, the precursor of a distinct planet, in each of which, how-
ever, the phenomena of ring-formation might be repeated, as

4 J?OCA'S AND SOILS.

proved by the existence of planctar}- satellites and of the pres-
ent rings of Saturn.

The period of transition from the original nebulous mist to
the resulting world-body has been divided into five phases, as
follows : First, the glowing, gaseous condition represented by
planetary mist. Second, the glowing, liquid condition repre-
sented by the fixed stars with constant light. Third, the slag-
formation, or the gradual appearance of a cool, non-luminous
surface. The sun is now undergoing the transition from the
second to the third phase; and this third phase is represented
by innumerable fixed stars, red in color and not constant in
light; stars which gradually but temporarily disappear from
view are in the transition stage between the third and fourth
periods. Fourth, the phase characterized by the violent burst-
ing of the solidified crust by the heated, glowing mass within,
and the sudden appearance or exudation of the same. This
phase is at present witnessed in the sudden appearance of an
illuminated star where before darkness alone was visible.

Fifth, the progressive thickening of the original crust, on
which the watery vapors begin to condense, followed by the
complete cooling of the heavenly body. Our Earth has passed
successively through the first four stages of cosmic growth ; and
exists now in the fifth phase of world-evolution.

We have traced the earth's progression, from its original
chaotic, nebulous, gaseous form, till the solid earth-crust, the
original condition of the geologic world, the time and condition
from which and with which geological history begins, appeared.

Geologically and chemically considered what was this condi-
tion ? What were the characteristics of this era? This origi-
nal solidification, these first rocks were how formed, and of
what did they consist ?

Fundamental Formation. The chief geologic forma-
tions of to-day are sedimentary in origin. The sea from which
the first sedimentary formation was precipitated must have
possessed a bottom over which it expanded and' on which it
rested. Precipitation necessitates a foundation or fundamental
material, and whether the occurrence be the result of mechani-
cal suspension or of separation from chemical solution, it must

IN TROD UC TION. 5

have origin in pre-existing material, or in a previous rock-
formation.

These axiomatic facts admit of but one conclusion, namely :
that the entire geological series of sedimentary formations are
secondary products of an older and non-sedimentary formation,
the fundamental crust. The latter cannot be other than the
original first product of the cooling of the molten mass of the
earth-ball.

It is doubtful if this primitive rock still exists anywhere in
the modern world sufificiently near the surface to be accessible ;
but possibl}' the gneiss of the archaic formation, the soft-
structured but slightly-stratified lowest deposit of the archaic
time, may be considered as the product of the surface cooling
of the fluid mass. In which case data are at hand for the defi-
nite determination of the mineralogical and chemical composi-
tion of the first primeval solidification.

The mass of our terrestrial sphere, with its surrounding
atmosphere included, has not materially changed from the be-
ginning to the present ; it is the same yesterday, to-day, and
forever. Its material cannot have diminished ; though, perhaps,
through the gain of attracted meteoric matter, it may have
infinitesimally increased.

New rock-formation occurs wholly by the transformation of
previously existing rock forms by means of water and atmos-
pheric influences, or through the cooling and solidification of
molten rock masses. The material of every fresh sedimentary
formation depends on the disturbing and rearrangement of
older strata. The entire stratification from the most ancient
complex to the precipitation occurring in the waters of to-day,
has derived its material from the same chief source; the
destruction, expansion, and re-formation of the original earth-
crust. This latter must, therefore, have contained, and con-
sisted of, the same materials from which the more recent, or
sedimentary, deposits are formed.

The predominating constituent of all sedimentary rocks is
silicic acid (SiO^). The occurrence is sometimes in the form of
quartz, and then as quartzite, sandstone or sand ; sometimes
in combination with bases forming silicates, the most common
of all, or more so than all other mineral-forms combined.

6 HOCKS AND SOILS.

Both silicates and bases are derived chiefly from the orii^in.-il
crust ; and the predominance of the silicates is due simply to
the fact that the affinity of these bases is such that they could
not exist in a molten condition in the presence of the acid
without combining with the same. It therefore follows that
the original rock-crust of the earth must have consisted chiefly
of silicates of the more common inorganic or mineral bases.
More definitely than this, the chemical composition of a for-
mation itself beyond examination, and necessarily judged
simply from its products, cannot be determined.

Geological like political history is divided into distinct ages,
eras, or epochs, each characterized by distinctive features
which render it independent and recognizable.

Four grand divisions of earth-history are recognized, the
chronologic position and geological features of which must be
borne in mind. These formation-groups, beginning with the
first or most ancient, are as follows :

I. ARCH^AN TIME.
II. PALEOZOIC TIME.

III. MESOZOIC TIME.

IV. CENOZOIC TIME.

CHAPTER I.
ARCH^AN TIME.

This first division of geological history begins with an age
preceding the existence of either animal or vegetable life on
the Earth. The period was universal in extent, the rocks of
this formation being the only ones of so extensive distribution ;
and yet, only the more recent deposits of Archaean origin still
exist exposed to view, and none of these present indisputable
evidences of organic existence.

The question of exactly when and where in the Earth's his-
tory the first forms of life made their appearance has long of-
fered a field for assiduous investigation and discussion. The

ARCH^AN TIME. 7

facts of modern biology seem to demonstrate that vegetable
and even animal existence became possible when the tempera-
ture of the waters condensed on the Earth's cooled rock-crust
reached 90° C, yet estimations made, indicate that the tem-
perature of the Earth's surface at the close of the Archsean
time was not above 38° C.

Though the remains of Archaean plants are themselves want-
ing, the best of presumptive proof is at hand to establish the
fact of vegetable existence during this period. Graphite is a
characteristic and widely distributed occurrence among the
rock-formations of this time ; and graphite is one of the three
allotropic forms of elemental carbon found in nature, and is of
undoubted organic origin.* Mineral coal of purely vegetable
origin is known to have been transformed into graphite, and in
New Brunswick the original coal-producing plants are to-day
preserved in the form of graphite. The amount of this form
of organic carbon existing in Archaean rocks is often 25^ of
the strata, and even traces of anthracite coal are claimed to
have been discovered in certain Archaean layers of Norway.

These facts seem to demonstrate that the close of the Ar-
chaean time was rife with the very lowest forms of plant-life,
cryptogams of the marine algae and lichen types.

These vegetable forms doubtless preceded the arrival of the
first animals, their existence being possible in waters of a
higher temperature and earlier date. And the lowest animal
organisms are so constituted as to feed on vegetable forms
which must thus precede them. The first members of the ani-
mal kingdom called into existence were doubtless the lowest of
Protozoans. It is even claimed that the remains of Rhizopods
exist in the calcareous strata of Canada and Bohemia. f The
close of the Archaean time probably found a world whose warm
brackish waters were the habitat of hordes of Protozoan life
finding sustenance in the abundance of algae, making it their
home,

* There is no impossibility in an inorganic origin for graphite as well as for the
diamond; but no evidence of such an origin is deducible.

f This conclusion is, however, based on analogy and not on the evidence of act-
ual organic remains.

8 V ROCKS AND SCILS.

Arch^an Rocks are classed in two general groups, known
as the —

I. PRIMARY GNEISS FORMATION.
II. CRYSTALLINIC SLATE FORMATION.

I. The Primary Gneiss Formation, or Lmircntian Period
of America, consists almost exclusively of metamorphic or crys-
tallinic rocks, the oldest sedimentary deposits to which geolo-
gists have access. They existed originally in the fundamental
crust, from which they were dissolved by the action of waters
impregnated with silicic acid, and, aided by heat, from the solu-
tion or mechanical suspension thus formed deposits of gravel,
sand and mud were made, from which the crystalline rocks
were evolved by time's transmutation. The rocks thus formed
embrace granite, mica-schist, gneiss, crystallinic limestone,
quartzite, conglomerate, feldspar and apatite, besides many
rocks of the hornblende series, as syenite and hornblende-gneiss.

The Distribution of these rocks is universal ; but since
only a very small portion of the Archaean world existed in an
unsubmerged condition, the accessible Laurentian deposits are
confined to a comparatively limited area. In America, the
formation is limited practically to the Atlantic slope of the
British possessions, though isolated localities of Laurentian
rocks occur in, perhaps, all the New England States, in New
York in the Adirondack region, along the Appalachian and
Rocky mountain systems, and on the borders of Lake Superior.
In Europe, the distribution is chiefly in Scandinavia, Scotland,
Bavaria and Bohemia. In Asia, the formation is confined to
the continent, and there chiefly north of the Stanovoi Moun-
tains.

II. Crystallinic Slate Formation, or Hnronian Period
of America. The rocks of this formation are deposited directly
on those of the earlier Archaean period. Like their immediate
predecessors, they are metamorphic in character, and of sedi-
mentary origin.

The formation is wholly devoid of organic remains; and the
definite boundaries of its occurrence are not accurately deter-
mined.

ARCHyEAN TIME. 9

The Rocks of this period are chiefly of a slaty character, in
conjunction with which occur conglomerate, quartzite, amphi-
bole, jasper, Hmestone and dioryte, the last-named usually ex-
isting in the form of dikes sometimes supposed to be eruptive
injections.

The Distribution of Huronian rocks is less extensive than
that of the preceding Archaean form. They were first studied
on the northern borders of Lake Huron ; but are now recog-
nized on the shores of Lake Superior, in Brazil, Venezuela,
northern Africa, Spain, the Swiss Alps, Tyrol, Bohemia, Scan-
dinavia and Scotland.*

Agricultural and Economical Characteristics of the
Archaean Formation. Since soils invariably contain the ingre-
dients of the rocks from which they were formed, their compo-
sition and characteristics partake of the general nature of the
rocks underlying them.

As a natural sequence the soils of Archaean regions are pre-
dominatingly clays, frequently cold and unworkable, or soils thin
and poor in character. The most interesting agricultural
feature of the formation is the abundant occurrence in certain
localities of apatite, native phosphate of lime which has recently
been largely utilized for the manufacture of superphosphate of
lime, the chief source of nutritive phosphoric acid.

Hornblende, so prevalent a rock-form of this era, invariably
contains considerable quantities of iron ore ; and this element
is an almost universal occurrence through the period, and
imparts the characteristic reddish color to many Archaean
rocks. It most frequently exists in the form of magnetite
(FegOJ, hematite (Fc^O,), or in the form of titanic iron ore
and franklinite, iron ores containing respectively titanium and
zinc.

The iron deposits of the Arch^an formation are thicker
and more abundant than in any succeeding age. To them
belong the Iron Mountain of Missouri, the iron ores of New

* The statement by Credner (^V^wt'w/^ Jer Geologie, Leipsig, 1883, p. 405) that
Huronian rocks exist in China and Japan is at variance with facts established by
the most recent sur\-eys.

lO ROCKS AND SOILS.

York and Michigan, and, above all, the famous Swedish iron
whose quality is unequalled.

Veins of lead, arsenic, cobalt, bismuth, copper, and silver ores
of Archaean origin also exist, the veins of the noble metal oc-
curring in Bohemia, Silesia, Norway and possibly Canada ;
sulphides being the prevailing form in which these metals exist.
Aside from the minerals of economical significance, others of
Archrean origin are noteworthy, including calc-spar, heavy-
spar, fluor-spar, quartz, orthoclase, oligoclase, mica, tourmaline,
garnet and topaz.

The crystallization of these minerals proves conclusively that
the Archaean time was subject to the prevalence of eruptive
phenomena, by the intense heat of which the transformation
and subsequent condensation and crystallization were rendered
possible.

CHAPTER II.
PALEOZOIC TIME.

The geological period and formation-group directly following
the Archaean is designated The Paleozoic Time, and is subdi-
vided into four distinct formations or ages:

I. THE SILURIAN FORMATION
II. THE DEVONIAN FORMATION.

III. THE CARBONIFEROUS FORMATION.

IV. THE PERMIAN FORMATION.

This time begins practically with the rocks containing the
first undisputed remains of organic life, which are chiefly wacke,
slate, sandstone, limestone and conglomerate deposits.

I. Silurian Formation, or
Age of hive -telratcs.
This formation received its name from Murchison, who first
thoroughly studied the rocks of the age in that portion of

PALEOZOIC TIME. II

Britain formerly inhabited by the Silures. The oldest known
fossils are of Silurian origin, and the number of varieties repre-
sented in these rocks, and the number of individuals present,
show gradual increase through the age, at the end of which
species closely allied to those of to-day, or even still existing,
are not unknown.

The formations of this age are of a very varied character,
giving rise to a widely diversified arrangement and classification
in the regions in which Silurian rocks abound. Two general
subdivisions of the formation are, however, universal : The
Lower Silurian and The Upper Silurian. In the lower strata
of the former, usually designated as the Primordial, the earliest
fossil remains exist, confined wholly to the lowest vegetable
and animal marine types; while the upper Silurian furnishes
the first land plant of geological history, a ground-pine (Lyco-
podium), occurring in the limestone of Cape Gaspe.

Silurian Rocks, both upper and lower, are mainly sand-
stones, conglomerates, shales and limestones, the first-named
being in the upper strata often of an argillaceous character.
The change here occurring in the character of the rock-forma-
tion, that is, in the composition and structure, marks an era in
the petrographic nature of the earth's surface, the varieties of
rock now appearing in predominating force continuing to be
the most frequent formations during all the succeeding ages of
geological history or earth-progression, and are the most com-
mon deposits of the present era. The sand-beds, fundamental
formation of the sandstone, the mud-beds, original form of
shales and argillaceous sandstones, and limestone production
have been constantly in progress, and are still to-day continuing
the process of rock evolution or formation. And wherever
during the world's history sandstone production has occurred,
shale or limestone has been brought into existence near at
hand; for the process of rock-pulverization producing the for-
mer, also results inevitably in the formation of the latter, sand-
deposits and mud-deposits being but different effects produced
by one and the same cause.

Among the petrographic characteristics of this era are also
the appearance in certain localities of quartzyte, silicic slate,

12 JtOCk'S AND SOILS.

marl, and the important carbonate of lime and of magnesia
known as dolomite, which not infrequently forms entire moun-
tains, or even mountain-chains.

The Distribution of Silurian Rocks is of wide extent,
though the area covered by them is less than that occupied by
succeeding formations.

In America the chief deposits are found in Canada, in the
angle between the Laurentian and Huronian regions, extend-
ing with a south-west trend along the Appalachian region into
northern Alabama, and west from Minnesota and Wisconsin,
there being important regions also in the central Mississippi
basin, in the Rocky Mountains and in arctic North America.

In Europe, besides the English deposits, Scandinavia, Russia,
the Hartz Mountains, Bohemia and west through Spain and
Portugal, important Silurian regions exist ; the Bohemian being
particularly rich in both flora and fauna remains.

Agricultural and Economical Features. Agricul-
turally considered, the regions of Silurian origin are of an
inferior nature. The soils are predominatingly clay, and
usually of an unproductive character; while the sandstone
regions are not infrequently occupied by barren heaths. In cer-
tain Silurian localities, however, usually where the sandstones
and calcareous deposits form conjunction, fertile lands occur
Avhose productiveness in the presence of marl may be of a high
order.

The peculiarity of the Silurian age, of by far the greatest im-
portance, is the prevalence among its rocks of rich mineral
deposits of iron, copper, zinc, lead, and less important ores.
They exist most frequently in the form of impregnations and
isolated enclosures in the surrounding rock-mass, the cavities
having doubtless been filled from above.

The minerals usually occur in the limestone strata, and exist
as sulphides. The American Silurian lead deposits existing in
the upper Mississippi Valley being the chief deposits of the
kind in the world.

One other peculiarity of the Silurian age is the isolated oc-
currence of anthracite coal-strata inserted between the layers
of rock;* a noteworthy incident from the fact tliat coal un-
* In " Etage H " of the Bohemian Silurian. •

PALEOZOIC TIME. j^

doubtedly of organic origin consists of very nearly pure carbon,
and }'et exists here as an occurrence of an era at first nearly de-
void of all life either animal or vegetable, and the organic re-
mains of which are almost invariably of animal salt-water origin.
Of a similar nature are the deposits of a poor quality of mineral
oil existing in many Silurian regions.

From the Silurian age also date a large proportion of the
productive rock-salt deposits from which many of the most
remarkable salt and mineral springs known take origin.

The Close of the Silurian Age found a world mostly
submerged beneath the waters of a shallow sea above which
only here and there solid land had yet appeared ; and on which
only a few of the lowest forms of vegetable growth found a
habitat; and the first land animals, scorpions, recently obtained
from the Upper Silurian of Sweden, Scotland and New York,*

The waters, however, teemed with life of many forms ; trilo-
bites, graptolites, forameniferae, corals, crinoids, and brachio-
pods, swam upon its surface, roamed through its depths, or
reared their curious structures above the waves.

Only at the very end of the Upper Silurian Age did the
fishes make their appearance, being the first vertebrates to cross
the world's stage, and thus forming a landmark, bounding an
era in geological progression.

During all the time embraced in the Silurian Age, our entire
planet, from pole to equator, possessed a regular and equable
temperature, a warm, humid, frostless climate unaffected by
change of season — facts abundantly demonstrated by the uni-
form distribution of remains of certain species of extinct inver-
tebrates, regardless of modern climatic conditions, proving the
universal existence, during Silurian times, of like conditions of
climate and atmosphere.

II. The Devonian Formation.
This forms the second epoch of Paleozoic Time, and is char-
acterized as the Age of Fishes.

During this era, the invertebrates of the brackish sea which

*Geike, Text-book of Geology (London, 1885), p. 665 ; American Journal 0/
Science, March, 1886, p. 228.

14 KOCKS AND SOILS.

covered so great a portion of the world, a fauna represented by
the goniatites, snails and nautilus of to-day, though far from
disappearing, lost the predominating character they possessed
during the Silurian Age, and gave place to vertebrates, mem-
bers of the order Pisces, thus marking a long stride in the organic
progression traceable through geological history. Here, in the
Devonian formation, occur the first ferns and coniferae in nu-
merous force, so that the flora of the age is as much character-
ized by vascular plants as is the fauna by the predominance
of fishes.

This age of fishes is remarkable for the abundance of organic
life which distinguished it. Its waters were the habitat of
myriads of invertebrate animals whose fossil remains form the
chief mass, or components, of many rocks traceable to a Devon-
ian origin. The name now universally adopted is derived from
Devonshire, England, in which locality the formation was first
systematically studied.

Devonian Rocks. Petrographically considered, the rocks
of the Devonian age possess much the same general character-
istics manifested by their immediate predecessors of the Silu-
rian age. The first rocks of Devonian origin consisted of the
corniferous limestone.'^ Nevertheless, the predominating rock
of the age was sandstone, which in frequency of occurrence so
exceeds all other formations that the era is still often designated
in England as the Old Red Sandstone age.

Other rocks of this formation, occurring more or less abun-
dantly, are conglomerate, shale, slate and schist, often bitumin-
ous in character, yielding even 20 % of combustible material.
The limestone of the Devonian period existed invariably in
the form of the carbonate, and was not infrequently of organic
origin, large areas of rock-formations of this age consisting
chiefly of the petrified remains of the lower organisms of the
Devonian era. The most interesting of these deposits being
where the formation consists of the carbonate of lime in the
form of vast fossilized coral-reefs. These calcium -carbonates

* So named from the presence of homstone, a variety of flint, the Latin for
" horn" being corttzi.

PALEOZOIC TIME. 1$

are not infrequently accompanied by carbonates of iron, so that
many profitable iron mines are located in Devonian regions,
where the ore occurs in combination with carbonates, the result
of organic petrifaction.

The formation is generally characterized as consisting of
three distinct deposits, the lower, middle and upper Devonian ;
and local variations in each of these subdivisions abound, par-
ticularly in America, where local designations are very numer-
ous, derived chiefly from the series as named in the State of
New York.

The Distribution of the Devonian Rocks is wide-spread,
there being no continent without them. The American region
is confined chiefly to New York, Pennsylvania, Michigan, Ohio,
Indiana, West Virginia, Kentucky, Tennessee, Georgia and
Alabama ; and the portion of Canada lying between Lake
Huron and Lake Erie, also in Nova Scotia and New Brunswick.

In Great Britain the chief deposits are found in Cornwall,
Devonshire, Herefordshire and Ayrshire.

On the continent of Europe the most noteworthy localities
are in Westphalia, the Prussian Rhine Provinces where the
Coblenz strata are especially well defined, in the Hartz Moun-
tains, Poland, Russia and Scandinavia, in all of which regions
the rocks are rich in petrifactions of both flora and fauna.

?'i Asia, Devonian rocks are distributed over a considerable
part of the northern and eastern portion of the continent. In
Japan, the oldest discovered rocks are Devonian in character ;
the first land of the Archipelago was evidently elevated above
the sea during the Devonian age, forming many small islands
connected into larger land-areas by continued elevation during
subsequent ages.

Agriculturally and Economically considered, the
Devonian age presents more interesting features than arc dis-
played by any preceding geological formation. Though the
Devonian rocks occasionally become converted into soils too
sandy to be productive, they more frequently form the most
fertile soils of the regions in which they exist ; many localities
of Devonian origin being famous for their productiveness and
agricultural value, as demonstrated in the Rhine Valley, in

1 6 K OCA'S AND SOILS.

Herefordshire, in the Genesee Valley with its proverbial wheat-
lands ; the oak-openings of Ohio and the heavy pine-lands of
Michigan being largely confined to soils of Devonian origin.

The industrial resources of this age are also of unparalleled
importance. The shales are of unequalled quality for flag-
stones, while the limestones yield, in certain localities, large
quantities of mineral oil, and not infrequently natural gas,
Avhich is utilized for illuminating, domestic and smelting pur-
poses.

The great petroleum-producing regions of the world all be-
long to the Devonian formation. That this mineral oil is
itself of Devonian origin is by no means proved. Indeed, it
seems more probable that the oil, being organic in character,
and a product of organic existence, chiefly vegetable, origi-
nated in an era more prolific in vegetation, namely, in the suc-
ceeding carboniferous age; and that it simply found receptacle,
and became reservoired in the caves and caverns of the older
and lower sandstone formation of the Devonian age. This
supposition seems further justified by the fact that mineral
coal, which is also organic in nature, occurs but very seldom
during this epoch, while bituminous coal, more nearly yet
allied to the oil in character, composition, and conditions of
formation, never occurs as a product of the Devonian age.

The iron ore, a chief economical product of this age, is not
infrequently the magnetic iron, but it most usually occurs as a
carbonate in conjunction with limestone, and, like limestone,
abounds in animal petrifactions. The Devonian red-iron-ore
(Fe^Oj) is very frequently of a phosphoritic nature, and the
rock in which the ore occurs is not seldom impregnated with
deposits of phosphorite, utilized as a fertilizing material, and is
a not unimportant addition to the sources of agricultural phos-
phoric acid.

Other mineral deposits of an eruptive nature, but existing
as products of this age, are the deposits of zinc, lead, copper,
sulphur and arsenic which usually occur as sulphides, permeat-
ing the Devonian limestone strata.

Another metal of exceeding value is confined exclusively to
rocks of this era. The great tin-yielding mines of Cornwall

PALEOZOIC TIME. \J

belong to this age, and have supplied the world with most of
this indispensable metal ever since the adventurous Phoenicians,
unaided by chart or compass, sought the shores of Britain for
supplies of this essential ingredient of the implements of the
Bronze Age in human history.*

The world which, during the Silurian age, had consisted of
little but a surface of brackish water, with here and there solid
rock-formations breaking the surface, began, during the Devon-
ian age, to assume more the character of dry land, which now
appeared with more definite form and complex contour, yet
was, in all probability, wholly unoccupied by animals.

Toward the close of the age, the land flora became abun-
dant, and reached a stage of development characterized by the
existence of palms and gigantic ferns, with which indications
of a tropical temperature the Devonian soil, though devoid of
all animal life, was decked. The sea, above which this land
appeared, passed, as the age advanced toward completion,
through a gradual change in the character of its inhabitants.
The few straggling fishes appearing in the uppermost Silurian
rocks increased to become the distinguishing feature of the
age ; and, though innumerable brachiopods, cephalopods, cri-
noids and corals existed throughout the formation, vertebrates,
that is, fish of the ganoid type, are the distinctive fauna of the
Devonian formation.

III. The Carboniferous Age, or
Period of Coal Formation.

This formation embraces an era directly succeeding the De-
vonian, and forms chronologically the longest period of Paleo-
zoic time, and is, perhaps, the most interesting and important
era of Paleozoic history.

Both interest and importance centre in the peculiar and
characteristic product of the Carboniferous age, an epoch the
remains of which shed so much light on the geologic history

* Rodwell, " Birth of Chemistry," p. 39.

1 8 R OCA'S AND SOILS.

of the world, and to-day play so great a role in the political
and economical history of our time.

The formation embraces a time remarkable for the preva-
lence of gigantic ferns, palms, lepidodendrous and sigillarian
vegetation, in profuseness and luxuriance never again occur-
ring. Accompanying this flora was a fauna characterized by
the appearance of the first land-animals, amphibians, the only
air-breathing creatures existing in the midst of myriads of
coral and crinoid life.* The Carboniferous age becomes, there-
fore, the era of vascular cryptogams as well as the age of am-
phibians; and marks the advent of air-breathing animals.
While the vast deposits of mineral coal distinguishing the age
owe their origin to the conditions of which they form a graphic
record.

The Carboniferous age proper was preceded by a marine
period, termed the SUB-CARBONIFEROUS Age, during which
much of the region now occupied by the continents of Europe
and America was submerged by a shallow, temperate, brackish
sea, from which limestone strata and occasional sand-beds were
deposited. It was also during this time that the fragmental
rocks forming the shales, conglomerates and sandstones of the
Appalachian region, a deposit several times deeper than the
limestone, were laid down.

The Sub-carboniferous limestones are composed principally
of organic remains, chief among them being the formation
consisting so largely of crinoids, from which fact the term cri-
noidal limestone has been applied to the entire Sub-carbonifer-
ous limestone deposit, which like all calcareous rocks of organic
origin exists as a carbonate.

The Distribution of Sub-carboniferous Rocks seems
to have been very general over all continents possessing de-
posits of the succeeding Carboniferous formation ; and the era
was one universally characterized chiefly as a time of limestone
deposit, which product of the age forms the famous " moun-

* Unless the Silurian scorpions prove to have been air-breathers, a question as
yet unsettled, as there seems to exist a difference of opinion as to the habits of the
few individuals recovered.

PALEOZOIC TIME. 1 9

tain-limestone" regions of Kentucky, Tennessee, and other
American localities. The States of Michigan, Illinois, Ohio,
Iowa, Missouri, Arkansas, Mississippi, Alabama, Virginia and
Pennsylvania, all possess extensive areas of this formation ;
while in Europe, England, Wales, Ireland, Belgium and Rus-
sia furnish the chief localities of this pre-coal-formation era.

The true CARBONIFEROUS Age, or period of coal-formation,
directly succeeded the submerged or the Sub-carboniferous;
and its distinctive product exists in a series of coal-beds, or
coal-measures.

The Rocks of the Age are chiefly shales, sandstones,
limestones, and conglomerates. The limestone stratum is usu-
ally an intervening rock occurring between productive coal-
measures ; while the conglomerate most frequently exists at the
base of a coal-vein, its foundation, as it were ; and is known
technically as the viillst one-grit.

These coal-measures are distributed with considerable reeu-
larity and evenness over nearly the entire geographical world ;
and prove the age of which they were the product to have
been of universal extent. They have filled the office of pur-
ve)'or of fuel and light to the world of succeeding ages, from
frozen Spitzbergen on the north to New Zealand on the south ;
and, encircling the globe from meridian to meridian, are suffi-
cient to resist man's depletion for long ages of industrial activ-
ity still to come.

Some idea of the extent of the world's coal-supply may be
gathered from the fact that the explored area of coal land of
this period within the United States alone is 190,000 square
miles; and on the North American continent 208,000 square
miles.

The thickness of the Carboniferous rocks, that is, the entire
depth of this formation is exceedingly variable, being in cer-
tain localities scarcely more than 100 feet, while in Nova Scotia
a formation more than 14,000 feet thick has been traced. The
maximum depth of the formation in Pennsylvania is about
9000 feet, though the coal-measure rocks themselves are not
defined below 4000 feet from the uppermost stratum.

The beginning of the coal-formation era was marked by a

20 KOCKS AND SOILS.

great change in the petrographical character of the world.
The submarine formations, the sandstones, shales and lime-
stones of the Sub-carboniferous age, became hidden by deposits
of sand or of gravel, which, in time, hardened into the gritty
rocks forming the niillstonc-grit, the underlying bed on which
the coal-measures rest.

Though rocks of similar character occur later through the
coal strata, they are of more recent origin, and of less exten-
sive occurrence, than those which mark the advent of the coal-
formation era.

For this reason the rocks of the Carboniferous age may be
classed in two distinct divisions, each characteristic of an epoch
in the history of the formation, the Millstone-grit and the
Coal-jncasiirc.

These two terms signify simply the two divisions of one and
the same geological age, the characteristic production of which,
the mineral coal, occurs as a phenomenon of only one era or
formation of the age. The millstone-grit and the coal-measure
are, as it were, two parallel formations, both belonging to one
age; chronologically identical, but petrographically unlike. In
other words, the rocks of the Carboniferous age containing
mineral coal are of the coal-measure division, while the rocks of
the same era which are destitute of productive coal-beds are
assigned to the division of millstone-grit.

Aside from the rocks and coal of the Carboniferous age, one
other occurrence is of importance: the frequent presence of
iron ore in combination with the coal-deposits. Indeed, the
Carboniferous rocks are very frequently impregnated with iron,
always in the form of a carbonate, though often in quantities
too small for economical working.

Another accompaniment of the productive coal-layers is the
bed of clay on which they frequently repose.* The iron is not
infrequently mixed with silica, one of the ingredients of the
clay, thus forming what is known as clay-iron-stone; though the

: ,^^

* This prevalence of coal, iron, limestone, clay and sand as products of one
formation is of inestimable industrial importance: the iron to be smelted, lime-
stone for its reduction, the coal for fuel, the sand and clay for building the furnace.
The iron region of Pennsylvania is thus favorably situated.

Fig. 4. — Carbonized Tree-trunks, imbedded in coal. (After Credner.)

' %?;^ . ^

Fig. 5.— Carboniferous Tree-trunk from English coal-beds. (After Mantell.)

( To /ace page 21.)

PALEOZOIC TIME. 21

pure carbonate is the mineral siderite, and in this mineral ex-
ist the most perfect remains of the organic life of the Carbon-
iferous age.

The rock-formation of this era is exceedingly irregular in
character and composition ; each and every rock ever forming
a part of the petrographical arrangement of the era ; at times
appearing in combination with every other rock of the age, and
under every conceivable modification to be wrought with the
given number of factors : the presence of rock-salt, gypsum
and dolomite not infrequently lending complexity to the form-
ation.

Mineral Deposits other than the coal and iron are char-
acteristic of the age. Gypsum, rock-salt, and dolomite, though
existing and increasing the rock-forms of the formation, are, in
importance and abundance, surpassed by several minerals of
distinctly eruptive origin; diabase and quartz porphyry being
most frequently the imbedding rock, usually occupying a posi-
tion between the strata of conglomerate, slate and sandstone.
Scotland is the chief locality where this eruptive action of the
Carboniferous age manifested itself. But the mineral wealth
stored in the Carboniferous rocks through this action is found
principally in the lead, zinc and copper ores of Northumber-
land, Derbyshire, Aix-la-Chapelle, and several localities in the
neighborhood of the Great Lakes in the United States.

A different product of this same action is the asphalt-de-
posit of the Albert Mine in New Brunswick.

Origin of Mineral Coal, and the Process of Formation.
The fundamental facts of the history of coal-formation are,
that the material consists of carbon, hydrogen, and oxygen,
in average proportions of (for anthracite) C 95^, H 2.5^, and O
2.5^; that these ingredients are of undoubted organic origin;
and that the organisms w'hence they were derived were un-
questionably vegetable in character.

Were evidence other than the chemical composition of the
product required, it is found imbedded in the coal itself, where
whole tree-trunks, indeed forests of trees, in all the stages of
transition, from perfectly preserved wood to wholly trans-
formed coal, with delicate leaves and tiny rootlets intact, attest

22 ROCKS AXD SOILS.

the truth of the hypothesis, and bear witness to historical and
scientific facts recorded by Nature herself ages before the first
modern mountain was raised above the sea, or the sea itself
had assumed definite form.

A single glance at the era of which the coal-fields were the
product must suffice for the present review of the Carbonifer-
ous age.

The separation of land from water had at the beginning of
the epoch become more distinct ; and the elevation of land
above the sea which resulted in the formation of the continents
of to-day went steadily forward during the continuation of the
era. The first land-inhabiting and air-breathing animals made
their appearance on the earth : scorpions, centipedes, thousand-
legged worms and lizard-like amphibians ; animals of so low an
organism that the heavy carbonic-acid-gas-impregnated atmos-
phere of the time sufficed for the aerification of their sluggish
blood. And on the earth thus inhabited forests of gigantic,
palm-like, morass-thriving trees flourished in a climate poison-
ous, warm, and laden with moisture.

The rank vegetation of such surroundings, composed largeh-
of the carbon so abundant in the atmosphere in which it grew,
completed its growth, and fell into the morass from which it
sprang.

Here under the partial exclusion of .lir, by the water present,
a slow and imperfect decomposition set in, and a natural char-
coal was formed.

Upheavals of nature followed ; deluge of water was succeeded
by avalanche of sand and mud ; ages succeeded ; heat and
pressure did their work ; brown-coal became bitumen, the
latter became anthracite ; mud and sand were transformed into
rock.

Convulsion succeeded convulsion ; inundation followed inun-
dation ; ages came and went ; the process was repeated and
continued till the vast deposits of the Carboniferous age were
complete, and the age itself gave way before Timer's geologic
progression, and its records became a part of geologic history.

Agriculturally CONSTDER?:i), the Carboniferous age was
productive of results, though incomparably less significant than

PALEOZOIC TIME. 23

the great industrial resources called into existence by it, still of
an importance equalling, if not exceeding, that attained by any
preceding geological era.

Hydrous calcium sulphate (CaSO^ -|- 2HjO) or gypsum, so
universally valued as a fertilizer under the name of " land-
plaster," and which when heated till its moisture is expelled
becomes " plaster of Paris," so important a factor in many arts,
is most frequently found as a product of the Carboniferous
age. The soils of coal-formation regions are usually poor when
the sandstones or shales form the surface-rocks ; but where the
" mountain limestone " of the Sub-carboniferous age is at the
surface, soils of remarkable properties are the result, — their
grazing qualities being unequalled. The renowned " blue-grass
region " of Kentucky supplies the best possible evidence in
support of the fact.

Close of the Carboniferous Age. The era of coal-
formation was one of great length, and of unceasing change.
Intervals of submergence followed the eras of luxuriant coal-
forming vegetable growth. Great forests and jungles of
acrogens and gymnosperms covered the continents ; but an-
giosperms had not yet appeared. Water-insects and marsh-
loving articulates teemed on land, vegetation and water; but
higher insects were as rare as the flowering plants on which
they live. Ganoids and sharks, but no osseous fishes, swam in
the waters. A few straggling reptiles foreshadowed the approach
of higher vertebrate life soon to appear ; but the first represen-
tatives of bird and mammalian life had not yet entered the
geological arena.

The continents were, for the most part, level expanses but
slightly raised above the boundless waters. Modern contours
were mostly lacking, and the few mountains simply traced the
areas of Archaean and Silurian existence. The elevation of
surface went gradually on ; new conditions appeared, and the
Carboniferous age, with all its phenomena, was at an end ;
and the arrival of new^ conditions ushered in a new era of geo-
logic progression.

24 ROCKS AND SOILS.

IV. The Permian Formation *

This was the final era of Paleozoic time, and marks a tran-
sition epoch, a time and formation lying between the coal-
building age and the era of higher developmicnt belonging to
the Mcsozoic time which followed.

Permian Rocks. Petrographically considered, the rocks of
this formation arc, in the eastern hemisphere, much more dis-
tinct from the coal-measures directly preceding them than in
the western hemisphere. In Europe, two independent divisions
of the formation are recognized, namely, the RotJilicgcndcs and
the Zechstcinfonnation ; and from this double or parallel for-
mation the term Dyas is given to the German Permian. On
the American continent, however, no distinction of epochs is
recognizable.

The lower and older strata consist mainly of sandstone, soft
and crumbly and devoid of mineral deposits; the Nczv Red
Sandstone of England, and the Rothlicgendes of Germany.
These strata are followed by marlites and magnesian limestone,
the ZecJistcinformation, interspersed with gypsum, copper-
bearing shales and the fetid organic-impregnated limestone
known as Stinkstcin, or bituminous limestone. Aside from
the regular rock-formations of the Permian age occur eruptive
stone, mostly granitic or porphyritic in character, and occasion-
ally accompanied by eruptions of sand and ashes of indisputable
volcanic origin.

The Distribution of Permian Rocks is in America
confined to a comparatively limited area, embraced within the
States of Kansas, Nebraska and New Mexico.

In England the formation is of considerable extent, particu-
larly in the northern portion of the country. It embraces two
distinct formations, the New Red Sandstone and the magne-
sian limestone.

In Scandinavia and Russia the formation is also met

* Dana makes the Permian a subdivision or ' ' Period " of the Carboniferous
age. But the independent formation is more frequently recognized.

PALEOZOIC TIME. 2$

with " ; but Germany is by far the region of chief Permian in-
terest, the most typical presentation being in the Hartz Moun-
tains, and in Thuringia, from the latter place stretching south-
ward with outcroppings in Bohemia and the Alps.

The Valley- and Basin - forming phenomena of the
Permian age are especially worthy of note, and are beginning
to attract no little attention. The limestone of this era is not
infrequently gypsum, and is invariabh- formed from anhydrite
by the absorption of water. This calcium sulphate, so readil)-
soluble in water, becomes worn away, and caverns in the Per-
mian formation are the result. These cavities frequently
become filled with salt-water infiltrations, and, in time, the
space originally occupied by the deposits of sulphate of lime
become filled with solid masses of sodium chloride.

This substitute product, equally soluble in water, also becomes
in turn dissolved, and a second hollow exists in the rock-mass,
frequently roofed by the soft sandstone of the New Red
Sandstone era. This frail covering not infrequently breaks
through, and an abyss yawns where solid ground existed but a
moment before.

These phenomena are advanced as explaining the frequent
earth-cavings occurring in the vicinity of Mansfeld in Prussia,
and other localities bordering the Hartz region in north
Germany.

The territory thus dropping below the surrounding surface
is not seldom of considerable extent ; and becomes filled v/ith
drainage-water, surrounded by flat shores and moors or
marshes, and even fertile meadows. The surrounding walls
are usually not complete, and a natural outlet for the accumu-
lating waters is thus formed ; and through the bottom-land of
the basin or valley into which the cavity becomes transformed
a small stream flows, the result of the valley formation, and not
its cause as previously supposed ; the erosive action of so insignifi-
cant a stream not being equal to the task of such extensive
valley-formation as exists, and which is rationally explained
only by these known phenomena of Permian origin.

* The Russian Permian occupies the extensive plain between the L'ral Moun-
tains and the Volga, in the ancient kingdom of Perm, from which fact the present
name was given the formation by Murchison.

26 ROCKS AND SOILS.

Agricultural and Economical Resources. Rock-salt
is not the only saline deposit dating from Permian times, as
salts of the alkalies and alkaline earths are of frequent occur-
rence among the rock-stratificatipns of this era.

The famous salt region of Stassfurt, remarkable as the only-
known productive deposits of salts of potassium, and to-day
the source of most of the potassium compounds of commerce,
arts and agriculture, and producing not only sodium chloride
and two salts of potassium, but salts of magnesium as well, be-
sides supplying more bromine than all other sources of this
element combined, is an important feature of the Permian
formation.

Several metals are also of frequent occurrence in workable
quantities in the Permian formation ; among them being some
which seldom occur as products of other ages. Notable among
these being cobalt, nickel and baryta ; besides which the era
was productive of rich deposits of several forms of copper, of
lead and of rock crystal.

The soils of magnesian limestone origin are most generally
of indifferent agricultural value, shallow and unproductive.
On the other hand, Permian soils formed from the New Red
Sandstone division are invariably of the first quality, fertile,
easily workable and productive.

The End of the Permian Formation marks the close of
a period during which the Earth passed through a remarkable
stage of development.

Beginning with a submerged epoch, it was characterized by
the gradual evolution of continents till the solid land had
assumed a form not unlike that which it bears to-day. The
progress of organic life kept pace with the advance in conti-
nental growth, till endogens were supplanted by exogens, and
the first lizard-like inhabitants of the solid land began to be
displaced by higher vertebrate animals; the poisonous carbonic-
acid-laden atmosphere of the Carboniferous age was succeeded
by an atmosphere capable of blood-o.xidation, and the Rcptiliafi
Age or Mcsozoic Time ; with the advent of which the world
entered upon a new era, an epoch of more highly organized ex-
istence.

MESOZOIC TIME. V

CHAPTER III.

MESOZOIC TIME, or

Age of Reptiles.

This third grand division of geologic time is divided into
three distinct periods:

I. THE TRIAS FORMATION.
II. THE JURA FORMATION.
III. THE CRETACEOUS FORMATION.

The first of these is, in Europe, further subdivided into the
Buntersaiidstein, MuseJuikalk and Keiiper; but, on the American
continent, there is hardly an imaginary distinction between the
Trias and the Jura formations.

The MESOZOIC Time may be properly termed the mediaeval
time of the Earth's history, an epoch characterized by the
culmination and decline of two great types in the animal
world, the Molhiscan and the Reptilian ; an age noticeable for
the existence of a flora and fauna more nearly allied to the
organic life of to-day, and distinguished by the appearance of
the first mammals, the first birds, the first modern or osseous
fishes, the first true palms, and a vegetation consisting chiefly
of dicotyledonous plants.

I. The Triassic Formation.

This formation, directly succeeding the Permian, derives its
name from its triple division in Germany. It marks a most
important epoch in organic progress as the period in which the
remains of the first mammalian existence occur ; and its rock-
formations are among the richest of fossil-yielding deposits.

Rocks. In the rock-formation of this period there is great
similarity between the American and the European, inasmuch
as both continents present a red sandstone as the chief petro-
graphic product of the era; but with the local complications of

28 JiOCKS AND SOILS.

the period pertaining to the continent of Europe we cannot
deal.

The New Red Sandstone formation of America demands
more careful consideration ; and next to this, the most import-
ant and frequent rock occurrence of the epoch is an impure
limestone. There are three separate Triassic regions defined on
the North American continent : the Atlantic-border region, be-
tween the Appalachian range and the coast ; the Western In-
terior region, including most of the Rocky Mountains; and the
Pacific-border region, extending westward to the Pacific.

To this era belong the sandstones of the Connecticut Valley,
the deposits in New Jersey and south through the Carolinas,
and the Palisades of the Hudson.

The sandstone of the period passes through all gradations,
from the fine-grained " freestone," undoubtedly a deposit from
calm, shallow water, to the coarse " pudding-stone" conglomer-
ate, the latter often occurring far-removed from its native bed,
showing evidence of long transportation, and the exertion of
mighty force for its accomplishment. Both sandstone and con-
glomerate are usually of granitic or gneiss origin ; and fre-
quently occur in very irregular stratification, proving the pres-
ence of strong water currents during the time of deposition.

A peculiar feature of the Triassic rock-formation consists in
the singular ripple or rain-drop markings on the upper surface
of the strata, due, without doubt, to the extreme shallowness
of the water from which the precipitation took place, and the
consequent partial surface-exposure of the rock above the
water-level.

Another peculiar occurrence in the Triassic formation is the
so-called ''bone-bed" found in^England and in Germany, as well
as in America : a limestone formation characterized by the
prevalence of innumerable fossilized bones of lower animals, es-
pecially of members of the orders rcptilia and amphibia.

Eruptive Phenomena. The entire Triassic region of
America is characterized by the remarkable outcroj^pings of
igneous rocks.

These ridges or dikes consist of trap of unmistakable vol-
canic or eruptive origin, which must have been ejected in a

ME so ZOIC TIME. 29

molten condition through extensive fissures made in the Earth's
crust. The most remarkable feature of the occurrence is found
in the fact that these eruptions seem to have been confined to
the Triassic region, and occur but seldom except as accom-
paniments of the Triassic formation.

The Palisades of the Hudson, and Mounts Tom and Holy-
oke in Massachusetts, are superior examples of this igneous
formation.

The eruption invariably occurred through the sandstone
rock ; and not seldom the sandstone was converted by the
intense heat into a hard grit, and was torn and rent by the
force of the accompanying explosion.

Another result of this phenomenon was the evolution of
vapors, whose condensation resulted in the tourmaline, hema-
tite and garnet crystals so frequently found in these trap-for-
mations. Copper, iron and barium ores are also among the re-
sults of this eruptive action.

Among Triassic phenomena, however, is one so character-
istic of the period that it may well be termed the Triassic
feature.

This is the frequent occurrence of FOOTPRINTS OF BIRDS
AND BIRD-LIKE REPTILES in the sandstone formation of this
age. These occurrences are nowhere more abundant, more
characteristic, or more perfectly preserved, than in the Con-
necticut Valley.

It remains a still-unsettled question whether any of these
footprints were actually made by true avcs ; but the probabili-
ties tend to prove that they all, or nearly all, owe their origin
to the presence on the Earth of animals closely allied to both
bird and snake, possessing, in a marked degree, characteristics
of both, yet distinct from either. That such animals existed is
not a hypothetical conclusion based on the well-known simi-
larity between the sub-kingdoms Reptilia 3.nd Avcs ;'^ nor on

* The recognized points of similarity between birds and reptiles are as follows:
They are either oviparous or ovoviviparous; the embryo possesses the amnion
and allantois; they are devoid of mammary glands; they never possess gills; the
skull is joined to the vertebral column by an occipital condyle; each half of the
lower jaw consists of several distinct pieces, and the jaw is not united directly to

30 ROCKS AND SOILS

the evolution theory that, in the progression from the lower
order to the higher, an intermediate existence must have been
passed. Beyond all controversy, such creatures are known to
have existed : their fossil remains attest the fact ; and they
undoubtedly belong to the epoch of Triassic formation; they
were of a lower organization than the birds which succeeded
them, and must have chronologically antedated the latter.
They unquestionably left their footprints on the sands of their
time, while true birds were but just appearing on the face of
the Earth, swimming in its waters, and traversing its sands, as
the Triassic era drew to a close.

Agriculturally and Economically considered, this age
is not one of marked features. The soils formed from Triassic
sandstone are, however, usually of a fertile nature, and in many
localities are of unusual productiveness; the soils of the Con-
necticut, Hudson, and Rhine valleys furnishing the best evi-
dence of this fact. The " bone-bed" deposits disintegrate into
superior soils, and the deposits themselves have been utilized
as a source of man u rial phosphoric acid.

The chief rock-salt deposits of Europe belong to this forma-
ation, the purity of the product being a noteworthy feature.
Freestone, " landscape marble," gypsum, local deposits of coal,
and " pudding-stone marble " are also valuable products of the
Triassic formation.

The Climate and Life of Triassic times were those of
mild temperatures over the entire Earth's surface ; but the first
evidences of zones of unlike climate began to appear and her-
ald the change approaching. The poisonous atmosphere of the
preceding era had been purified through the assimilation of
carbon by the vegetation and its subsequent conversion into
stores of coal.

A decided step forward occurred in the organic existence of
the world ; animals requiring better air and more perfect blood-

the skull but to an inten'ening quadrate bone ; the alimentary canal tefminates in
a cloaca which receives the secretions and excretions from bowel, kidney, and
sexual organs; the red-blood corpuscles are oval and contain a nucleus; the cavi-
ties of the chest and abdomen are not separated by a diaphragm; the hemispheres
of the brain are not united by the corpus callosutn.

MESOZOIC TIME. 31

oxidation make their appearance. One mammal, a marsupial,
the Droniathcriu))i sylvcstrc, one individual alone of which
species has been recovered from its place of preservation in the
Triassic rocks, marks the culmination of Triassic life.

II. The Jurassic Formation.

The middle member of the Mesozoic group most closely re-
sembles the preceding formation in the composition of its
strata ; but the absence of marine fossils being one of the most
characteristic features of the Triassic rocks, so the presence of
large numbers of these individuals furnishes the chief and best
evidence of the Jurassic character of a formation of Mesozoic
time. Indeed, the age is distinguished by the prevalence of
new and more highly developed marine animals in innumera-
ble varieties, and more closely allied to the representatives of
the same orders with which we are to-day acquainted.

Ammonites, belemnites, corals of the form of to-day, gastero-
pods and mollusks in unprecedented number now appear ; while
the shark-like fishes begin to be supplanted by the fish of
modern times. Reptiles become less abundant, and birds be-
come more abundant ; while the single Triassic mammal, semi-
oviparous, is succeeded by several varieties of low-organized, but
placental, mammals.

Rocks. Aside from the prevalent rocks of the Triassic pe-
riod, limestone, slate and clay are frequent occurrences during
the Jurassic era; and the limestone is not seldom in the form
of gypsum. Jurassic strata occur in America in the Black
Hills, in Colorado, and over considerable portions of the Pa-
cific slope.

The European Jura is subdivided into the Lias, or black
Jura, the Dogger, or brown Jura, and the Malm, or white Jura.
But in America no subdivision has been attempted, or can be
found to exist.

The Climate of the Jurassic period, as is proved by the
even distribution of life over the Earth's surface, was one of
equableness ; and the predominating forms of life indicate a
tropical, or semi-tropical, temperature for the entire Jurassic
world.

32 JWCKS AXD SOILS.

The existence of Jurassic fossils of undoubted marine origin,
high above the present sea-level, proves that the water-level of
the world was then much higher than now ; or rather, that the
continents have undergone a material elevation since the day
when salt-water mollusks were stranded high up among the
Rocky Mountains.

The Distribution of Jurassic Rocks finds chief display
in Europe, where the formation bears invariably a triple char-
acter. The extensive formation of England extends across the
Channel, through France, Germany and the Alps, from a spur
of which the name " Jura " is derived. The three subdivisions
are each distinctive, and present features typical of European
geology.

The American region is confined almost exclusively to arctic
latitudes, and to localities in Dakota, Colorado and the Pacific
coast. This latter region stretches southward into the Andes.

The Agricultural and Economical characteristics of
the period are of significant importance. The soils of Jurassic
origin are predominatingly clays, and largely heavy and tena-
cious ; but marl is of frequent occurrence, in which case the soils
are capable of becoming the best of wheat-lands, and of fur-
nishing most valuable pasturage. Gypsum is the only mineral
product of agricultural value.

But the great deposits of gold- and silver-bearing quartz in
Dakota, Colorado, Nevada, and California, the richest gold-pro-
ducing regions of the world, are confined to the Jurassic forma-
tion.

The Eruptive Disturbances which were so noticeable a
feature of the Triassic period were but mere trifles compared
with the eruptive development which closed the Jurassic era.
Whole mountain-ranges date from this time, and were forced
above the surrounding surface by internal power which built
up barriers of igneous rock in the midst of Jurassic deposits.
The entire Sierra Nevada formation is of such origin ; and, like
these eruptive strata, is characterized by the presence of exten-
sive veins of pure quartz.

The heat of the eruption converted the water present at the
place of outburst into alkaline solutions of silica, which, filling

ME so ZOIC TIME. 33

the crevices and lower levels, solidified and became silicon di-
oxide or the quartz reefs. And in these reefs of quartz exist
to-day the gold, silver and other metals gathered from the sur-
rounding softer formations, and afterwards condensed and so
lidificd with the mass of the solution. And to this phenome-
non is due the existence of these auriferous quartz veins in the
midst of the surrounding Jurassic formation, and gives the pe-
riod an interest and value it might otherwise fail to attract.

With these convulsions of nature, carried on with such
grandeur and on a scale of as significant magnitude as of geo-
logical and industrial importance, the Jurassic period came to a
close, and was followed by the final epoch of Mesozoic time.

III. Cretaceous Period, or
Era of Chalkfonnation.

This epoch closes the Reptilian age, and is signalized by the
extinction and disappearance of innumerable species of mol-
lusks and reptiles, and the appearance of many modern types
of plants ; so that the period is distinguished by a great revo-
lution in the flora of the Earth. Though the palms and coni-
fers of the Jurassic period did not disappear, they were now,
for the first time, accompanied by members of the great order
Angiosperms, which includes the maple, oak and most of our
modern fruit and forest trees.

The Distribution of the Formation in America is un-
important from its extent, and is divided into the so-called ear-
lier and later Cretaceous epochs, in neither of which, however,
with a single exception located in the State of Kansas, does a
true deposit of chalk occur ; though deposits assigned to this
formation exist along the Atlantic coast from New Jersey to
South Carolina, across the Gulf States, up the Mississippi Val-
ley, over the interior portion of the continent, in the Rocky
Mountains, and on the Pacific slope.

The most typical, the most diversified, and the most thor-
oughly studied Cretaceous formation is in England, where the
chalk deposits and Cretaceous rocks cover a large portion of
the territory; and where the chalk cliffs glistening in the sun,
3

34 HOCICS AND SOILS.

contrasted against the blue of the sky, and flanked by the green
of field and wood, form a most striking, beautiful and charac-
teristic feature of the landscape.

The English formation is subdivided into the Loiver-grccn-
sand, Gault, Uppcr-grcciisand, Chalk-marl and Chalk ; which
names indicate clearly the character of the CRETACEOUS RocKS
which consist chiefly of beds of Greensand, of marlite, clay,
and shell-limcstonc ; while many American deposits contain
hornstone corresponding to the flint of England.

The Cretaceous formation, petrographicalh' considered, is ex-
ceedingly irregular in composition. Its deposits pass through
all gradations from fine, pure quartz sand, sandstone, conglom-
erate, hard and soft limestone, marl, magnesian limestone, chalk
and flint; so that many localities classed as belonging to this
period possess but the slightest possible resemblance to
other deposits of the same era. It, therefore, follows that the
petrographical features of the formation often fail to determine
its geological position, which must depend on its paleontologi-
cal characteristics for correct designation.

Agricultural and Economical Interests of unusual
importance characterize the Cretaceous formation ; the period
not infrequently yielding mineral coal, gold, copper, iron, chro-
mium; and, most important of all, the chief quicksilver-produc-
ing regions of the globe are of Cretaceous origin. The great
natural deposits of cinnabar (HgS) occurring in the metamor-
phic rocks of California, Mexico and Spain being of the chalk-
formation era.

Eruptive stones cannot be considered characteristic of the
Cretaceous epoch, but are of occasional occurrence accom-
panied by zinc, calc-spar and strontianite, and not infre-
quently consisting mainly of basaltic rocks ; while mineral as-
phalt is a characteristic accompaniment of Cretaceous eruptive
action, the chief asphalt mines of France and Germany existing
in districts belonging to this formation.

Chalk (CaCO,) of organic origin, the charactei^istic prod-
uct of the Cretaceous formation, is a nearly pure, unsilicious
carbonate of lime, consisting almost wholly of the remains of
microscopic foraminifera, aquatic by nature, and deposited

MESOZOIC TIME. 35

by precipitation from the sea-water of the Mesozoic time. A
cubic inch of chalk may contain upward of a million of these
small Rhizopods.

It is generally conceded that the flints so prevalent in forma-
tions of Cretaceous origin are not of a metamorphic character,
but are the product of the aggregation of silicious infusoria be-
longing to the same era as the foraminifera, and, like them, de-
posited then as they are to-day in the waters of the deep sea.

The Grccnsand of this period owes its characteristic color to
the presence of silicate of iron, and is of considerable agricul-
tural value as a fertilizer known as " marl," and is extensively
excavated in New Jersey. Its agricultural value is due to the
presence of silicate of potash, and of phosphate of lime of un-
mistakable organic origin, as proved by the presence of bones
and shells of marine animals.

The soils belonging to this period are, as a rule, of excep-
tional fertilit}', especially those in proximity to the upper
Grccnsand, with its supplies of potash and phosphoric acid.
The clay soils of this formation, though in themselves heavy,
become remarkably productive when in contact with a sub-
stratum of chalk, being in England noted as producing barley
of rare quality,, and being chiefly devoted to the culture of this
grain for malting purposes. Hops and wheat are also remark-
ably successful crops grown on tiiis soil.

No more interesting or instructive comment can be made
on the agricultural properties of Cretaceous soils than the fact
that " Rothamstead," the renowned experiment farm of Sir
John Lawes, is situated in a Cretaceous region. The soil has
now borne forty-five consecutive crops of wheat without ma-
nuring, and still, at the end of this protracted drain upon its
resources, produces more than twelve bushels of grain per acre,
a yield almost equal to the average product of the United
States.

The soil which has thus, at the end of nearly half a century
of constant depletion, shown itself incapable of exhaustion is
typical of a large area of soils of Cretaceous origin. It consists
of a tenacious yellow clay, thickly interspersed with nodules of
flint. Beneath this surface-formation, at a depth of twelve

36 ROCKS A. YD SOILS.

feet, exists the chalk, containing abundant organic remains of a
phosphatic nature, and potassium being present in appreciable
quantities.

As a result of this fortunate conjunction of circumstances,
the gradual but constant decomposition of the mineral constitu-
ents present as products of the Cretaceous formation supplies
the plant with all the essentials for its growth and maturity,
with the single exception of nitrogen. The addition of this
one ingredient to the chalk-formation soils of " Rothamstead"
would render them practically of exhaustless fertility.*

The Climate of the Cretaceous period is characterized by a
gradual lowering of temperature from that of the epochs pre-
ceding it ; and the regular and even temperature universal on
the Earth during the Paleozoic age had now, at the close of the
Mesozoic time, assumed more of the zone aspect of to-day,
though nowhere is there evidence of anything approaching a
frigid temperature ; yet evidences of the occasional existence of
floating ice are not wanting. The climatic conditions of the
Cretaceous period were those of transition from the warm or
temperate condition characteristic of the primeval and mediae-
val Earth to the frigid era which ushered in the modern epoch
of geologic history. Only a slight transformation was required
for the beginning of an era of ice and frigidity, and this change
occurred here at the close of the Cretaceous era, when disturb-
ances took place which revolutionized the geographical aspect
of the world, and swept it free of the organic life which then
characterized it.

The European continent forced itself above the waters sur-
rounding the archipelego of which the Europe of Mesozoic
time consisted. The mighty range of the Rocky Mountains
reared its peaks thousands of feet above the highest pre-Creta-
ceous level. The change of elevation brought frigid, ice-
bearing currents down with resistless force upon the temperate
lands of the chalk-formation era, sweeping from existence with
their frigid, blighting breath almost every vestige of the lower
semi-tropical fauna and flora of the Earth.

* The relations between nitrogen and mineral matter as food for plants are con-
sidered in Part Third.

CEXOZOIC TIME. 37

The characteristic features of Mcsozoic time vanished ; new
conditions prevailed ; and a new era, the Cenozoic Time, was
at hand.

CHAPTER IV.
CENOZOIC TIME.

The primeval stage of organic existence gave way to an era
of greater advancement which was, in turn, supplanted by a
mediaeval epoch. The lapse of ages continued, progression the
watchword, till both these phases were relegated to the past,
leaving only their petrified history behind ; and the modern
era of geologic evolution, the recent period or Cenosoic timCy
appeared.

Invertebrates, fishes, reptiles, predominated in turn, and
characterized each an epoch in the series we are tracing ; and
now all retreat to the insignificant position they must occupy
in an age marked by the numerical superiority of the order to
which the genus homo is assigned. Mammals now predomi-
nate, and the arrival of man, for whose reception the world has
passed through all this epoch after epoch, and age on age, of
preparation, is near at hand.

The Cenozoic Time, characterized by the predominance of
mammalian animals, is divided into two periods, the distinction
between which being marked by the evidences of man's pres-
ence on the Earth. These epochs are :

I. THE TERTIARY FORMATION, or Age of Mammals.
II. THE QUATERNARY FORMATION, or Age of Man.

I. The Tertiary Formation.

This age was characterized as the period during which the
Earth's surface began to assume its present geographical form
and appearance, and became the dwelling-place of a fauna and

38 A'OCA'S AND SOILS.

flora more closely resembling its modern inhabitants, a con-
siderable number of species of which have not become extinct,
but live to-day, representatives of races predominating then.

The chief characteristics of the Tertiary world, by which it
becomes more closely allied to the world of to-day, are as fol-
lows : First, a continual increase in distinctness of demarkation
between solid land and sea. Gradual elevation and depression
of the surface, always, however, with a final gain of elevation
on the part of the land, and a constant withdrawal of the waters.
A condensation of the sea; the drj'ing up of marshes; the
draining of lakes whereby rivers flowed where inland seas once
had been, and valleys succeeded great basins filled with the
fresh or brackish waters of ages of accumulation, — these were
distinctive Tertiary phenomena resulting ever in land forma-
tion and water-repression within boundaries closely conforming
to those with which we are still familiar.

Second, the formation of modern mountain-chains. The
chief of the lofty mountains of the world date from the Ter-
tiary age ; the highest peaks of the Pyrenees and Alps, of the
Himalayas, Andes and Rocky Mountains, being of this recent
origin. The elevation of such lofty summits inevitably changed
the water-sheds and river-courses of the previous era ; and ex-
erted no inconsiderable influence on the fauna and flora of the
Earth, through the resulting meteorological and climatic modi-
fications.

Third, the formation of climatic zones. During the earlier
periods of the history of our planet, it possessed, from pole to
equator, an even temperature, the record of which endures to-
day, and informs us that Silurian corals and the luxuriant
vegetation of the Carboniferous world, alike, flourished with
equal perfection of growth under equatorial skies and in the
midst of polar seas ; for the interior heat of the Earth was still
so manifest at the surface, that the uneven distribution of the
sun's rays was of little influence on terrestrial temperature.

Gradually, but constantly, as the surface-crust becamte thicker,
the external temperature became lower, till now at the begin-
ning of the Tertiary age the surface-manifestation of internal
heat had nearly ceased, and modern climatic distinctions were

CENOZOIC TIME. 39

the result. Asa natural and inevitable consequence, the fauna
and flora which had before been so evenly and regularly dis-
tributed over the Earth became restricted to habitats whose
confines they could not pass with impunity; and whole races
of animals and plants became exterminated through the action
of new climatic influences. The survival of the fittest ensued ;
and the existence of those species unprepared for the new sur-
roundings in which they were placed became a part of geo-
logical history.

Fourth, the total extinction of many animal and vegetable
forms, and the restricted existence of others. The life so
characteristic of earlier ages, of Carboniferous, Cretaceous and
later formations, but more particularly the giant Reptilia of
the Mesozoic epoch, passed away with scarcely a living repre-
sentative to preserve the memory of their existence ; and a
new order, a higher development, succeeded them ; a modern
era began.

Fifth, the extraordinary development of animal and vegetable
types whose first appearance on the Earth is characteristic of
Mesozoic time. The Angiospcrms, which first came to notice
as remains in the upper chalk-formation, become now the pre-
vailing type of forest tree ; mammals, the first feeble and im-
perfect representatives of which class date from the upper
Triassic period, now first assume the typical mammalian form
of monadclpJiian, placental animals whose young are brought
into the world in a more fully matured condition.

The oldest typical mammal dating from the Tertiary age was
the so-called Anoplotherium, which possessed several charac-
teristics of the ruminant family, and was followed by true
ruminants and carnivora, till the fauna lacked only the genus
homo to present all the species of the world of to-day.

Sixth. The gradual appearance of innumerable varieties of
mollusks identical with the marine fauna of to-day. So near
did the youngest Tertiary or most recent period of the age ap-
proach the present, that from 60 to 90 per cent of these mol-
luscan varieties imbedded in Pliocene formations are identical
with the present or living members of the same family.

The features, then, by which the Tertiary age may be dis-

40 ROCKS Ai\D SOILS.

tinguished are chiefly these : deciduous trees, mammals, bi*
valves and gasteropods become the predominating representa-
tives of the organic world ; with a gradual separation or di-
vision of the Earth into climatic zones, each with itsdistinctiv^e
fauna and flora, and depending for its characteristics upon its
remoteness from the equator. These climatic influences ap-
proach nearer and nearer those of to-day, and become compli-
cated through the rearing of lofty mountain-summits with
their various zones of temperature. And as the ancient con-
ditions recede, and those of the modern world approach, the
number of animal and vegetable forms identical with those of
to-day assume ever an increasing ratio. The diversity of ter-
restrial conditions and of organic life far surpasses anything
that had preceded them, and marks the last stage of progres-
sion before the arrival of that still existing.

The Tertiary Age has been divided into three separate
■epochs or eras, as follows :

1. Eocene (dawn of the recent), with species nearly all ex-
tinct.

2. Miocene, whose species are less than half living.

3. Pliocene, the species of which era are more than half still
living.

The Rocks of the Tertiary period are divided into two
kinds : those of fresh-water deposition, and those precipitated
from salt or brackish water, the marine deposits. So character-
istically different are these two formations in their essential
features, that the character of the rocks serves as an accurate
register of the extent of salt- as of fresh-water occurrence during
-the Tertiary formation.

Beginning with the first or oldest deposits, we find beds of
sand or clay, followed by compact sandstone, beds of loose
shells and earth, shell-rocks and calcareous sandstones. These
rocks are of a firm texture, suitable for building purposes.*
Then follow marls and clays, with carbonate of lime from pul-
verized shells, compact solid limestones, greensand identical

* St. Augustine, Fla. , the oldest city of European building in America, consists
chiefly of edifices built of this stone.

CENOZOIC TIME. 4 1

with that of the Cretaceous formation, and buhrstone used for
millstones.*

As is seen by the list, Tertiary rocks are as a formation much
softer than those of any preceding era, yet the epoch produces
hard slates and sandstones wholly indistinguishable in them-
selves from those of earlier strata.

Like the Cretaceous age, the Tertiary also contains beds, or
deposits, of a silicious Infusoria, and of calcareous Rhizopods.f

The Tertiary limestones are largely made up of fossilized
Rhizopods, called Nummulites, existing often at great altitudes,
forming many Alpine and Himalayan summits; beds of a kin-
dred nature occurring among the Coast Range in California.

Distribution of the Rocks. Geographically considered,
this age was one of most extensive domain; and all the conti-
nents possess examples, and no insignificant ones, of the for-
mation. It was the last epoch of the Earth's history preceding
the advent of man ; and as such embraces much of the new
land-formation bordering the oceans of the world, being to a
great extent the formerly submerged surface exposed by the
final receding and restriction of the waters.

In America, this area includes Cape Cod, the islands ofT the
Massachusetts coast, most of the coast south of New Jersey,
the peninsula of B'lorida, portions of the Mississippi Valley,
where distinctive water-sheds for the Mississippi and Ohio
rivers existed, the streams each emptying independently into
the sea, and only becoming united at their mouths toward the
close of this era. The Rocky Mountain region and the Pacific
coast also present well-defined marine beds of Tertiary origin.

In Great Britain, the Tertiary deposits are chiefly Eocene,
and are confined to a triangular region, embracing southeastern
England, surrounding London, and extending inland nearly to
Salisbury. Northern France contains beds of a similar nature.
Germany, Switzerland, Italy, Greece, northern Africa, southern
Asia, most of Japan, and the islands of the Indian Archipelago,
possess Tertiary deposits.

* South Carolina yielding a famous quality.

f Dana's " Manual of Geology," pp. 493 and 512.

42 /a OCA'S AND SOILS.

The Volcanic or Eruptive Action with which the age
came to a close manifested its power over the entire Earth ;
and the display of the activity then begun has not yet disap-
peared as a real and vital force, present and manifest. For
the volcanic and earthquake actions of the present are most in-
timately connected with, and in all essential characteristics
most closely allied to, the phenomena of Tertiary times.

Several distinct epochs of eruptive action seem to have passed
over the Earth during the Tertiary age ; or rather, different por-
tions of the Earth's surface were undoubtedly subjected at
varying intervals to the influences of eruptive action.

The chief result of this occurrence, as witnessed to-day, is
evidenced by all the great mountain-chains of the Earth, which
either date wholly from a Tertiary origin, or by this action
were elevated thousands of feet above the highest altitudes
previously attained. Long periods often elapsed between these
intervals of eruption, so that the formations resulting therefrom
are of varying age ; but always of the same petrographic char-
acter, the rocks being igneous in nature, and consisting princi-
pally of basalt, porphyry, and other plutonic rocks.

Most of the active volcanoes of our day date their periods of
activity from Tertiary times, — the lava of modern Vesuvius
having its exact counterpart in the formations antedating the
era of man.

The Agricultural and Economical features of this age
are in many respects unique. In America, the soils are chiefly
of a sandy nature, and frequently of slight agricultural capabil-
ity ; but clays also are characteristic of the period, and a con-
junction of the two often results in a soil of extraordinary fer-
tility,— clay with a sand subsoil being a favorite and productive
arable land, while the clays alone form superior pasture-lands.
Above the Tertiary clays extensive heaths and marshes abound,
wholly sterile, but capable, by drainage, of being converted into
valuable meadows. The extensive artificial cranberry-meadows
of the Cape Cod region and of New Jersey belong to tl^is class
of phenomena, and exhibit the transformation of worthless
wastes into unusually valuable land.

In England, areas of similar nature are well known; while in

CENOZOIC TIME. 43

Japan such tracts form extensive districts along the coast, and
between the highlands of most of the islands.

Deposits of phosphate of lime, of animal origin, are unique
features of the Tertiary of America and England. South Caro-
lina, in the so-called " Charleston basin," possesses the world's
largest supply of this essential manurial material. The deposits
exist in the form of hard phosphatic rocks, which are exten-
sively mined and exported to all the States and to most Euro-
pean countries for manufacture into superphosphates for fertil-
izing purposes. The rock abounds in fossil remains, but is
itself probably of a fossilized guano nature.

The crag-formation of England, embracing the larger part of
the English Tertiary, is also remarkable as containing vast
quantities of hard flinty nodules consisting often of even 60%
of calcium phosphate. The subsoils of this region formerly so
abounded in these fossils that extravagant prices were given
for the right of digging and removal for use in the commercial
fertilizer industry ; but the supply of these so-called coprolites
has of late years become much depleted.*

An interesting occurrence of the Tertiary age, and one of no
little scientific and agricultural importance, is the fact that
grasses, to the growth of which more than half of the arable
world is devoted, date from the middle of the Eocene ; no gra-
minaceous fossils existing in older formations, and the fauna
of pre-mid-Eocene times having been wholly unfitted by its
dentition for existing on any form of grass.f

Coal and lignite abound in most Tertiary regions. The
former is invariably either soft or brown coal, and is not uncom-
monly of very superior quality. Deposits of this fuel are
worked in Colorado and many Rocky Mountain regions, in
England, Germany, India and Japan. The last-named country
possesses exhaustless resources of superb Tertiary coal in several
localities both of Nippon and Yesso. The lignite, sometimes
confused with brown coal, possesses its original woody texture,

* "Elements of Agricultural Chemistry and Geology," Johnston and Cam-
eron (13th ed.), p. loi.

f American Naturalist, June '86, p. 546.

44 /BOCA'S AND SOILS.

and forms a fuel rcsemblin<j charcoal, though more durable. Its
chief deposits occur in Continental Europe ; Hesse and Bruns-
wick both furnishing large supplies of this fuel.

Bog iron ore (2Fej03-|-3H,0) exists frequently in Tertiary
formations, and often in valuable deposits.

The infusorial eartJi, consisting of the remains of the minut-
est infusoria, and so important a factor in the scientific and
political world of the present generation as an ingredient of
dynamite, is an abundant product of Tertiary life. The chief
deposits exist in Germany and in the State of Virginia, though
occurring widely as a formation of this era.

The Climate of the Tertiary Age was, at the beginning,
over at least a portion of the Northern Hemisphere, one of
tropical or semi-tropical nature; and this character extended to
the regions of the midnight sun, fossil evidences being abun-
dant that even Greenland and Spitsbergen possessed during
these early times a climate of comparative mildness, being
luxuriant in the verdure of the temperate zone, and the home
of vast forests of deciduous trees, through which roamed the
mammoth and other gigantic mammals which became extinct
races by means of the same causes to which are due the death
of the forests and the advent of perpetual and impenetra-
ble snow.

Gradually as the centuries of Tertiary time rolled away, the
formation of our modern climatic zones became perfected ; the
cycle of formative phases was complete ; preadamic conditions,
surroundings and influences were at an end ; man's domain was
ready for his occupancy, and the last epoch of geological his-
tory arrived.

n. The Quaternary VovMxiioYi.ox Age of Man.

The appearance of man on the Earth marks the arrival of a
new geologic age; all efforts to establish evidences of the ex-
istence of pre-quaternary man having failed when put to the
further test of scientific inquiry.* The Quaternary period is

*Lyell, "The Antiquity of Man" (London, 1S73); de Nadaillac, Z«/r«'///iVrj
hommes et temps prehistoriques (Paris, 1883).

CF.XOZOIC 'II ME. 45

divided into two epochs or formations: i, TJic Diliivuim, or
formation immediately following the Tertiary ; and 2. The
Alluvium, or period of to-day, which embraces the modern
deposits and formations still in process of completion, the peat-
bog being a characteristic illustration of this class of phenomena.

The American Quaternary is, however, classified more ex-
plicitly as —

I. The Glacial Period; 2. The Champlain Period;
and 3. The Recent Period, or period of Terrace forma-
tion.

The intermediate epoch, or Champlain period, is wholly
American, and of secondary importance here; while the Glacial
is the characteristic epoch of the Ouarternary age.

The phenomenon of the age was the gradual moving down
from polar regions, over the three northern continents, of
enormous masses, fields and mountains of ice, resembling in
nature enormously aggravated glaciers, resulting in the so-called
Drift formation.

Heretofore the phenomena of geological history had pos-
sessed a southern trendor tendency ; their field of action having
been mostly confined to the southern portions of the conti-
nents. But now there is a radical change in the location of
active geological progression. The continents which have
heretofore been gradually extending themselves toward the
south have reached the limit of this expansion ; and the active
phenomena of the period approaching are all northern in their
origin, and exert themselves most powerfully in regions never
since wholly freed from the bonds of ice and snow.

THE glacial or DRIFT-FORMATION PERIOD.

This was an era distinguished by the presence of enormous
fields of inland ice and glaciers which covered the greater part
of the North American and European continents, half of Asia,
and large areas in South America;* moving gradually but
irresistibly southwards, burying all nature beneath its frigid

* Confined to the higher altitudes, or to the vicinity of the Pacific coast.

46 ROCKS AND SOILS.

mantle, passing unresistingly over lofty mountains, and grind-
ing rocks to powder and gravel which became deposited in its
path, a formation of veritable Drift material.

As the term implies, this formation consists of gravel, sand,
clay, and boulders existing in an unstratified condition, which
have evidently been transported from a distance, usually from
localities of higher altitudes. So powerful and resistless was
this action, that rocks hundreds of tons in weight were trans-
ported many miles, and that, too, independently of grade,
surface-slope, or incline.

Drift may occasionally exist in a stratified condition, possess-
ing the same composition as the unstratified, except that the
lower stratum is usually of clay interspersed with enormous
boulders which confer the name Boulder clay upon this level.
The unstratified Drift is invariably wholly devoid of the remains
of marine life, though vegetable material is of frequent occur-
rence. The stratified formation occasionally presents marine
fossils.

The material of the Drift varies with the geological character
of the region whence it was transported. The usual distance
of transportation seldom exceeded one hundred miles ; and the
course pursued ^vas invariably from the north, or in a southerly
direction. In Europe, the southern limit of this glacial action
was in northern Austria; while in America a more southern
limit was attained, — portions of the States of Maryland, Vir-
ginia, Kentucky and Tennessee being of unmistakable Drift
origin.*

The western limit of this phenomenon was near the Missis-
sippi River of to-day. There were also smaller glacial regions
in the Rocky Mountains and the Andes. The amount of ice
depending on the amount of precipitation, the chief seat of the
phenomena must have been confined to the vicinity of the
great oceans.

The characteristic phenomena of this era were of a kind
clearly establishing the identity of their cause. f Aside from
Drift deposits, the abrasion of the surface-rocks was universal,

* American /nm-nal of Science, 1 886.

KiG. 6.— Glacial Scratches. (After Hitchcock.) (To face page ^q.)

CENOZOIC TIME. 47

SO that the entire rock-formation in Drift regions is left in a
scratched, grooved, furrowed, or polished condition. The
bottoms of valleys, the bed-rock beneath the accumulated
di^bris, are usually scratched, so that it seems the Drift itself
must have been deposited after the era of abrasion, while the
height of the grooving above the sea, on the sides of the val-
leys, or on mountain-peaks, shows to a nicety the depth of the
icy inundation to which the continent was subjected. Instances
in the White Mountains exhibit these markings at an elevation
of 5500 feet ; and the complete burial of mountains under the
moving millstone of ice is strikingly illustrated by Mount
Holyoke, whose summit is a surface of furrowed and polished
trap, enduring evidence of the chastening process to which it
was subjected.

Closely allied to this furrowing of surface-rocks is the occur-
rence on all continents subjected to glacial action of Fiord Val-
leys,"^ deep, narrow, canon-like channels grooved in the rock,
occupied by the sea, and extending often long distances inland;
the tide pouring through them like the waters of swift-flowing
rivers, confined within dark and narrow chasms, winding some-
times a hundred or more miles from the sea between towering
rocky walls.

Origin of the Glacial-period Phenomena. The
causes of the change in climate resulting in the phenomena of
the glacial period were chiefly these : The preceding Tertiary
age had been one of unusual increase in elevation above the
sea, an era of continent-formation closed by an unprecedented
period of lofty mountain elevation. The rearing of these
mountain-summits far above the greatest elevation previously
attained was necessarily followed by a marked lowering of tem-
perature throughout the region subjected to the action. To
augment this reduction of temperature, the great changes of
surface-elevation over entire continents resulted in disturbances
of the relations before existing between land and sea; old
currents were annihilated, and new currents came into being.

* The coasts o^ Maine and of Norway presenting most characteristic illustrations
of these phenomena.

48 A'OCA'S AXD SOILS.

The upheaval of land was chiefly in the south; the waters
displaced were driven northwards ; and to occupy the space
vacated, frigid currents poured in from the polar regions, fol-
lowed by an era of ice and arctic cold overall the land subjected
to their influence. The Northern Hemisphere became buried
beneath the icy burden, so powerful a factor in moulding the
geological features of the age in which it existed and exerted
its force.

That other causes than continental elevation might have
exerted an influence on the change of temperature ushering in
the Diluvian epoch is extremely probable, as explained by Prof.
Miiller, particularly with reference to the supposed second
period of glacial action ; but he advances the change in eleva-
tion as the paramount influence resulting in the reign of cold,
and calls attention to the fact that, at the beginning of the
Diluvian period, the English Channel and much of the German
Ocean were high and dry above the sea-level of the time.*

The Cause for the Southivard Movement of the lee-mass. As
already stated, surface-incline exerted no influence on the direc-
tion of glacial movement ; and the course of advance was in-
variably from the north.

Most of the new ice was, of course, made at the place of low-
est temperature; and as climatic zones already existed, this
region of greatest cold was farthest from the Equator, that is,
toward the north. It therefore followed that all new ice was
added to the mass at the north ; all increase in iveight and
pressure took place at the north. The chief melting, the loss
in mass and weight, occurred at the south. The latter was,
therefore, the point of least resistance. The mass of accumu-
lated ice moved steadily onward in this direction, driven by the
resistless force of the weight increasing at the north. And
this movement continued till amelioration of temperature re-

* " In einem fruheren Zeitabschnitt der Diluvial-periode, ehe die erwahnte grosse
Senkung eintrat, welche die europaischen Tiefliinder unter den Spiegel der Nord-
und Ostsee tauchte, ragten diese Lander hoch viber dem Meere empor, wrenigstens
so hoch, dass nicht nur der Canal von Calais, sondern noch ein grosser Theil der
Nord- und Ostsee trocken lagen." — Muller, Die allesten Spuren des Menschen
in Europa, p. 13.

CENOZOIC TIME. 49

duced tne mass through melting at the south faster than it
accumulated through freezing at the north, when this mighty
force gently melted away and disappeared, leaving only its
records deeply graven on the geologic page over which it
moved.

The occurrences of this era were undoubtedly the result of
the action of ice in some form, for the magnitude of the results
accomplished preclude all idea of their having been produced
by the action of water. But the power of ice might have been'
exerted in two ways, or the ice might have existed in either of
two forms: either as moving glaciers, or 2^'^ floating icebergs.

The Iceberg Theory presupposes the inundation of a
large portion of the Earth's surface where continents now ex-
ist. Indeed, the Drift formation and region of to-day must
coincide with the area of submergence. New England must,,
then, have been submerged to a depth equal to the highest ele-
vation at which the impress of floating ice is exhibited, or at
which the groovings and scratchings of to-day attest the action.

But opposed to this theory is the fact that throughout the
Drift area no marine fossils remain at an elevation greater than
500 feet. The average distance of Drift transportation is
hardly more than 50 miles, yet icebergs carry their imbedded
masses and rocky burdens even thousands of miles. Masses of
ice floating in the currents of a frigid sea, or driven hither and
thither by the winds, could hardly have scored so regularly the
entire surface of the country, or have so systematically fol-
lowed the courses of the valleys. A more reasonable hypothe-
sis in explanation of the phenomena is

The Glacial Theory • * the truth of this supposition be-
ing indicated by the following facts.

The very phenomena characteristic of this period are being
produced to-day by glacial action ; stone and gravel being
taken up by the advancing glacier, and transported any dis-
tance, either long or short.

The scratching and grooving made by glaciers still extant are
identical, in every respect, with those of the Drift formation.

* AgaL.is\z, Systeme glaciaire (1847); Geikie, "The Great Ice Age" (London,
1873).
4

50 IWCA'S AND SOILS.

The Rhone glacier in Switzerland offers the best field for ob-
serving the results of modern glacial action, from the fact that
the glacier is gradually receding toward its parent ice-field,
leaving in its path a perfect record of the results attained.
The deep gorge, down which it moves like a massive, frozen
Avaterfall, bears high on its sides indisputable abrasions of
surface-rock ; and the deposition of ice-polished boulders at-
test glacial action, while the infant Rhone flowing from beneath
the ice-mass, and, muddy with the sediment and pulverized
rock of sub-glacial origin, passes over an expanse of loose peb-
bles and boulders, at first so recently bared by the icy inunda-
tion that no vestige of vegetation appears ; but as distance
from the ice-wall and remoteness from glacial action increases,
a few scattering sedges appear, and the vegetation continues
to gain in quantity and quality till, a mile from the present face
of the glacier, verdant meadows begin.

The debris remaining in the bed of the vanishing glacier pre-
sents every feature characteristic of the Drift of Diluvian ori-
gin; and the Rhone glacier is but the feeble remnant of a
mightier glacier of Diluvian time, filling with its comrades the
entire region between the Alps and Jura; and over whose en-
tire territory the results of its presence still exist, counterparts
of the phenomena still taking place as the Rhone glacier re-
cedes and decreases, just as all the mighty mass of which it is
so slight a remnant vanished with the Diluvian epoch.*

The presence in temperate climates of varieties of Alpine or
polar plants may be explained on the ground of glacial trans-
portation.

The number of plant forms thus assigned an arctic origin is
very great. They exist in various parts of Europe, and on
most of the higher peaks of the Alleghanies, the Adirondacks,
White Mountains, and Green Mountains, in America.

* The rate of annual retrogression of the Rhone glacier is marked each Septem-
ber by the Swiss national survey, and is by no means insignificant, the average
yearly rate of disappearance being about 30 metres; and sometimes far exceeding
this amount. In 1882 the amount of recession having been, as measured by the
author, 58 metres. Amelioration of climate in the Alpine region of Europe keeps
price with this recession of its glaciers.

CEiXOZOIC TIME. 51

The Erosion of the glacial period consisted of two kinds:
the abrasion caused by the stones at the under surface; and a
scooping action resulting from the forward movement of the
ice.

The chief erosive results accomplished by the glaciers were
produced directly by the water, accumulating beneath the mov-
ing ice-mass in consequence of the constant melting of the same.
These sub-glacial streams were loaded with the jagged stone
masses broken from the rocks over which the glacial pathway
lay. These, rolled and whirled and revolved against the rocks
in contact with which they were driven by the waters, or
pressed by the ice, became like so many millstones or polishing
wheels, driven for the purpose of reducing the rock-surface to
gravel, sand or cla\'.

Where such action continued for a great length of time, par-
ticularly if the moving stone was harder than the rock against
"which the erosive action was exerted, deep well-like excava-
tions, extending perpendicularly into the softer strata for many
feet, were often the result. A noteworthy occurrence of such
phenomena exists in the sandstone strata near the Lake of Lu-
cerne, where in the " Gletscher Garten," close by Thorwaldsen's
renowned Lion of Lucerne, in an area hardly one acre in extent,
32 of these deep whirlpool pits appear; the chief of them be-
ing 26 feet wide and 30 feet deep ; and in the bottoms fre-
quently remain the one or more hard stone masses to whose
rotation by the sub-glacial waters through centuries of time
the deep erosion is due.

The rate of motion could never have exceeded one foot per
day, yet the pressure was so great and the weight so enormous
that all depressions of surface were filled or destroyed. The
lower level of the moving mass adjusted itself to the surface
over which it passed ; the loosened material was taken into the
ice-mass, Avhere, by the motion or agitation resulting from the
constant change of level, it was kept in perpetual movement ;
stones were ground against stones, and the fine debris from such
action became deposited as pebbles, sand and earth, — the gla-
cier being among the chief soil-producers of geological history.

The deeper river valleys owe their excavation to the erosion

52 KOCKS AXD SOILS.

of the glacial period, the result being partly due to direct ac-
tion of the glacier, but mainly to the existence of sub-glacial
streams laden or armed with debris from the glacier itself.

Not river-valley only, but also lake-basin excavation is at-
tributed to glacial action. Sometimes the efTect being the re-
sult of direct excavation. Or the outlet of a deeply excavated
valley became filled with glacier residue, Drift, till the valley
became a water-shed, and the stream a lake. Such was the
origin of many a deep lake in the Swiss Alps, reflecting the
green of vineyard and forest against the white of mountain
summit, with blue of sky above.

Following the phenomena of glacial origin came the forma-
tion of the Diluvianand Alluvian eras, classed together as a dis-
tinctive period, the Champlain, of America, existing chiefly in
the vicinity of the lake of this name.

The Rocks of the period were of two kinds : those dropped
from the glacier after the period of thaw began, being invari-
ably unstratified ; and those which fell into water on being
severed from their original mass, or deposited, where they were
taken up and transported by water in which they became
somewhat stratified.

During the Diluvian period of Cenozoic time the Earth
completed its formative history,* and Man, the highest type
of mammalian life, made his appearance, and assumed sway
over the lower creatures of nature's domain. " That Man was
a contemporary of the Diluvian animal world, no doubt can
now be entertained." f

The fauna with which he was coexistent was one clearly
fitted for arctic life; and man himself at this early stage of his
history was of an Esquimau character,;}: inhabiting a world
which, though supporting hordes of animal life, was still largely
given over to glacial action and vast areas of snow and ice.

* So far as we of to-day are concerned this is true, yet the age in which we
live is doubtless but an era in the progression toward a more advanced epoch to
follow.

•)■ Credner, Elemente der Geologic, p. 742.

X Miiller, Die dltesten Spur en des Menschen in Europa (Basel, 1876), p. 30.

Fig. t. — Hunter in the act of spearing a Diluvial Buffalo, Carved on Reindeer Horn, and
recovered from the caves oi Southern France in 1S69. ^ After Nadaillac.) (,To face f> age 53.)

CENOZOIC TIME. 53

The mastodon, mammoth, rhinoceros, reindeer and bear,
which constituted the predominating mammalian Hfe, were of
gigantic form, and were protected from the severity of their
native cHmate by coats of heavy hair and wool.

Not only are human bones found mingled with the remains
of all these animals, together with the rude weapons by which
they were often slain, but in many of the caves once forming
the only dwellings of the human race, beneath the accumulated
ddbris of Dilu\-ian convulsions, and ages of subsequent accu-
mulation, pieces of bone and ivory have been exhumed carved
with representations of the animals with which men were then
most familiar.

The number of the remains of gigantic elephantine forms
recovered from Diluvian regions in all parts of the world is
well-nigh innumerable.

In North America, they are chiefly of the family mastodon
gigantciis, preserved principally in the peat-beds of New York,
New Jersey and in the regions of the Missouri River. In
South America, the mcgatJieriw)i was recovered from the cen-
tral plateaus, often at an elevation of more than 7000 feet.*
In Europe and northern Asia, the predominating form was
the mammoth.

" There is not in all Asiatic Russia, from the Don to the ex-
tremity of the promontory of Tchutchis, a stream or river in
the banks of which they do not find elephants and other ani-
mals now strangers to that climate. These are washed out by
the violent floods arising from the thaw of the snows ; and
have attracted universally the attention of the natives, who
collect annually the elephants' tusks to sell as ivory." f

Credner estimates the number of individuals thus unearthed
during the last 200 years at 20,000. %

The two earliest periods of human history have been often
named, from the animal races most abundant then, as the period
of the mammoth, and period of the reindeer. But the distinc-
tion thus made is of doubtful accuracy.

* Von Humboldt, " Cosmos."

f Buckland, Rt-Uqtiicc DiluviancB (London, 1S23), p. 183.

X Credner, p. 739.

54 KOCA'S AND SOILS.

The geologic periods covered by mans existence, from the
time of the earhest and rudest remains to the period of au-
thentic history is divided into the —

1. STONE AGE.

2. BRONZE AGE.

3. IRON AGE.

The terms thus appHcd are, however, of more convenience
than of strict accuracy.* The people of Asia and Egypt en-
tered upon the Bronze Age of their history while Europe was
still only in the midst of its period of Stone ; and the Bronze
of northern Europe was not displaced by Iron till the third
century A.D. ; and many savage people have not yet emerged
from the Stone Age of their existence, and may never advance
beyond this stage.

Prehistoric man, as is attested by the relics left behind when
he disappeared from the world, was at first a dweller in caves
and caverns, a shelter supplied him with no constructive effort
of his own. But these first men seem to have been succeeded
by a race of perhaps universal lake- or river- dwellers ; for the
pile-supported residences first discovered in the Lake of Zurich,
and later in all the Swiss lakes, have since been supplied with
counterpart structures in Ireland and Scotland and throughout
Northern Germany.f

Rut though the human race thus occupied the lowla'nds and
even the water itself, their four-footed contemporaries were
not lim.itcd in habitat. Yet the great altitudes from which
bones of Diluvian quadrupeds are sometimes recovered is no
proof of so lofty a habitat, but rather evidence of more ex-
tended and mightier glacial action.

Buckland:}: records the discovery of such relics in central Asia
at an elevation of 16,000 feet. And though he adduces the
fact in support of a universal deluge, our present knowledge
draws evidence of the unusual depth to which the Asiatic pla-
teau must have been inundated by the Diluvian ice.

* Heim, Aus der Geschichte der Schopfung (Basel, 1872), p. 30. ^'

f De Nadaillac, Die ersten Menschen der Prdhistorischen Zeiten (1884), pp.
68-76

X 1. c, p. 223.

CEXOZO/C TIME. 55

The recovered evidences of man's progressive existence dur-
ing the Stone Age are as follows: i. Buried human bones,
and flint implements, with chippings caused by the manufac-
ture of the latter. 2. Arrow-heads and other implements
made of horn and bone, chiefly of the reindeer of the Diluvian
epoch. 3. Bored or notched bones, teeth or shells. 4. Cut
or carved wood, bone, horn, ivory or stone, ofteil carved in
the shapes of living species, or engraved with their likenesses.

5. Bones split that the marrow might be extracted for food.

6. Charcoal and other traces of fire used for cooking or warm-
ing. 7. Fragments of potterj^^.

This era was succeeded by the Bronze Age,* to which
period belongs Trojan history. Then followed the IRON Age,
extending to the present, and covering most of the years of au-
thentic history.

Lyell f asserts the existence of a veritable Copper Age be-
tween the eras of Stone and Bronze ; and numerous facts seem
to demonstrate the truth of this hypothesis. Switzerland,
Hungary and America furnish incontestable evidence that men
existed whose weapons and implements were of pure copper ;
while the excavations made by Dr. Schliemann in Troy de-
monstrate that the Trojans themselves used copper long ages
before their knowledge of bronze began, or while the latter
was esteemed as a precious metal, and regarded in the same
category with gold and silver.;}:

The Agricultural Interest of the Diluvian Period
centres chiefly in geologic evidences of the birth of agriculture,
resulting from human necessity.

Man's first step as an agriculturist, his first advancement
from a gatherer of wild fruits and slayer of his fellow-animals,
was doubtless made when he first domesticated some of the
latter, and compelled them to minister to his needs.

The second period of the Stone Age doubtless witnessed this
stride in human progress. Nadaillac records the change in

* De Nadaillac (" Prehistoric America," p. 180) proves no age of bronze to
have ex'sted in America, though evidences of an age of copper abound,
f Lyell, " Antiquity of Man," p. 10.
X Rodwell, " Birth of Chemistry," pp. 30-40.

5b A'OCA'S AXD SOILS.

these words : " Two great facts predominate the new phase
upon which humanity now entered : agriculture and the breed-
ing of domestic animals. Fire was doubtless the agent which
in the hands of these men rendered agriculture possible.
Thanks to the potent action of this element, forests were re-
duced to ashes, and meadows, henceforth to be indispensable,
took their places, and cultivation began. And the caves in
which these progenitors dwelt were invariably located in close
proximity to the fertile valleys and unfailing streams. ... In
the caves innumerable bones of cattle and sheep are found,
but of wild animals all traces are lacking. These facts, as well
as the character of the weapons and implements, make it evi-
dent that the people of this period subsisted chiefly on the pro-
ducts of their herds."* Again, the same investigator, in re-
cording the characteristics of the Lake-dwellers of Switzerland,
remarks: "During the long winter months domestic animals
require regular feeding ; therefore, wherever these animals ex-
ist we may expect to meet with evidences of agriculture." f

And in support of the assertion, the earliest submerged
dwellings of the Swiss lakes, those with abundance of Stone
Age implements, abound in remains of domestic animals ; and
in the houses of the next era, together with copper and bronze
implements and remains of smelting-furnaces proving the
metal to have been of home manufacture,:}; exist, side by side,
bones of sheep, swine, cattle, dogs and cats, with wheat, barley,
peas and beans.

The fact seems proved by incontestable evidence that agri-
culture, beginning in the middle of the Stone Age among all
peoples, has progressed as man himself has advanced ; and that,
through all human history, the agriculture of a people has fur-
nished the best evidence of the degree of civilization to which
they have attained.

* Les Hommes prdhistoriques.

fl.c.

t Muller, 1. c, p. 48.

CENOZOIC TIME. 57

THE ALLUVIAN FORMATION.

These deposits are those of recent origin, even now in pro-
cess of formation.

The chief phenomenon of the period was the formation of
the so-called Terraces, numerous in most lands, but nowhere
more characteristically presented than in the valley of the Con-
necticut. They usually possess flat summits which have been
levelled by the erosive action of water. These different levels
rise tier above tier from the river-bed ; and often border the
stream in unbroken lines for miles of its course ; each level or
terrace having been at one time the bed of the stream, the
repeated receding of which left the striated or terraced
formation, so picturesque in its effect on the landscape of the
present.

The Recent, modern or present period possesses Rocks of
four distinct modes of formation:

Of Mechanical origin, due to the action of water from which
they are universally deposited ; as, for instance, the alluvial of
river valleys or bottoms, and estuary or delta formation.

Of Chemical origin, as stalactite formations, silicious deposits
from hot springs, and deposits of bog-iron-ore.

Of Organic origin, as peat-beds, sea-beach deposits of shells,
coral formations, bird excrement or guano, and Rhizopod and
other deep-sea-mud deposits.

Of Igneous origin, as lavas and other ejections from vol-
canoes, or fissures in the Earth's surface.

The Agricultural Aspects of the Alluvian period are, so
far as their geological conditions are concerned, the features of
to-day. The soils arc invariably of fresh-water deposit, and
consist of the most finely pulverized material detached from
the rock-mass by the disintegrating forces, and, borne away by
the rains, gains access to streams, and by them is swept sea-
ward, either to be deposited along the valleys traversed, or
carried on to increase the delta-formation being built up at the
river's mouth.

But whether the formation exist as inland river-bottoms, or

58 IWCKS AND SOILS.

as islands formed at river-mouths, it is invariably the most
fertile of soils, and not infrequently rendered exhaustless by
constant accretions of water-sediment coming with every flood.
The changes and formations of this era, however, are of the
present. Their history is unfinished, but embraces the chem-
istry of the processes by which the Earth's surface was brought
into the condition in which it became man's dwelling-place ;
and is made to furnish sustenance for the ever-increasing needs
of the ever-multiplying human family.

PART 11.

ROCK COMPOSITION AND DECOMPOSITION.

CHAPTER I.
CLASSIFICATION AND COMPOSITION OF ROCKS.

Having followed the Earth through the various phases of its
formation till the world of to-day, the inhabitable home of
man, has been evolved by ages of geological progression, we
find the solid portion of our planet, the geological structure as
finally completed, composed of rock and soil, the latter contain-
ing all the chemical elements of the former, from which it was
produced by physical and chemical action and change.

The chemistry of the soil, then, its composition and char-
acteristics, can be studied only through the rock from which it
was formed.

As the soil is the product of rock decomposition and trans-
formation, so is the rock the product of mineral aggregation.
The properties and decomposition of rocks are, therefore,
fundamentally determined by the properties of the minerals
composing them.

The Systematic Classification of Rocks offers difficul-
ties which have as yet prevented the production of an arrange-
ment which shall combine the advantages of answering the
demands of our present scientific knowledge of the origin and
composition of rocks with the simplicity required of a practi-
cal working system.

Proposals and attempts at a solution of the difficulty have
been made by chemists, geologists and mineralogists ; and

6o EOCKS AND SOILS.

still one of the most eminent of them all admits that "as yet
no one has succeeded in producing a perfectly consistent and
comprehensive system." *

Systems based on chemical composition, on physical proper-
ties, and on the origin of rocks, have been introduced, and
have found advocates and followers. But rocks are not definite
compounds ; no fixed composition can be assigned to, or dis-
covered in, rocks of a given kind ; and still greater uncertainty
arises from the fact that a given composition as determined by
analysis may belong to many rocks of widely-varying nature.
The analysis presenting results of 72^ SiO,, i \fo Al^O,, 2.8^ FeO
and Fe.O,, \fo CaO, i.2<fo MgO, \.2% K,0, 2%, Na,0 8.4^ H,0,
might answer equally well for granite, gneiss, felsite, granulite
or quartz-porphyry.

It therefore follows that a classification based on chemical
composition fails to furnish the requisites of accuracy and
simplicity. Physical properties are hardly more satisfactory as
a means of determination.

Rock-origin, therefore, remains the most acceptable and
widely adopted basis for rock-classification. But even here we
are met by variations of application both important and numer-
ous. From a mineralogical standpoint, the arrangement of all
rocks into five varieties, —

I. Igneous Rocks ;
II. Metamorphic Crystallinic Schists;

III. Sedimentary Rocks ;

IV. Rocks of still doubtful origin ;

V. Rocks consisting of but one mineral ;
—as proposed by Von Cotta, is perhaps the most acceptable.
Still, Dana's division into three groups —
I. Fragmental ;
II. Crystalline;
III. Calcareous;
— offers advantages of simplicity and conciseness.

For our purposes, however, as students of rocks as related to
soils, still greater simplicity is attainable without the sacrifice
of either exactness or accuracy.

* Von CotU, " Rocks Classified and Described " (1877), p. 115-

CLASSIFICATION AXD COMPOSITIOX OF KOCKS. 6 1

All rocks may bo considered either as crystalline or as non-
cry'stalline. We adopt the former as our first division, and the
" Fragmental " or " Sedimentary" will form the second group,
while the " Calcareous" of Dana may be assigned to either
section as the individual rock chances to be of crystalline struc-
ture or not. For our purposes, then, rocks are of two kinds :
I. Crystalline ;
II. Non-crystalline.

Each group is further considered as embracing rocks both
simple and complex^ according as one mineral alone, or more
than one, enters into the composition of the individual.

I. Crystalline Rocks.

The cause of crystallization varies with different kinds of
rocks, three methods or conditions of crystallization being
recognized.

1. Solidification tJirough cooling, resulting in rocks kno^\•n as
igneous or eruptive, embracing all varieties of rock resulting
from exudation of molten material through fissures in the rock
crust of the Earth, of which the trap dikes form the best illus-
tration.

2. TJie action of long-continued heat belozu the point of fusion,
resulting 'va'vietavwrphic rocks, that is, transformed rocks, the
conversion of sedimentary or non-crystalline rocks into rocks of
a crystalline texture, the conversion of mud, sand or gravel
into granite and gneiss, furnishing examples of such trans-
formation, which does not affect the order of deposition or
stratification.

3. Chemical Precipitation. All natural waters hold carbonic
acid gas (COJ in solution, which compound greatly increases the
solvent power of the water. Alkaline carbonates are more
readily attacked by this dissolving agent, the insoluble mono-
carbonates being thus converted into soluble bicarbonates. If
now the water holding the compound thus formed be subjected
to heat or become evaporated, the excess of carbonic acid
being volatile is again set free, and an insoluble carbonate is
again formed. Lime is the base, and limestone the rock, most

C2 A' OCA'S AND SOILS.

often thus affected ; the abundant stalactite and travertine for-
/nations of so many regions owing their origin to this chemi-
cal reaction. Sihcic acid (SiOJ present in waters effects a
similar transformation by the conversion of soluble compounds
into insoluble silicates which become deposited because of the
conversion. Geyser regions, the hot waters of which are so
impregnated with silicic anhydride, furnish extensive areas of
such deposits.

Waters containing an alkaline solution may dissolve the silica
of tripolite, infusorial earth, a deposition of which results in the
formation of flint or chert.

Having reviewed the origin of the crystallization of rocks, let
us consider the chemical composition of the minerals compos-
ing these rocks, and which, through them, enter into the com-
position of our agricultural soils.

CRYSTALLINE ROCKS (SIMPLE).

Quartz constitutes not only the principal mass of most
rock-formations, but exists in several isolated forms, as rock-
crystal, quartzite and quartz-sand. Chemically speaking, the
mineral is anhydrous silicic acid or silica (SiO„). It forms
transparent hexagonal crystals, so excessively hard as to scratch
glass.

Feldspar is, next to quartz, the most abundant mineral in
nature. It is a green, yellow, brown or gray compound of
SiO^ with alumina and one or more alkalies or lime. There
are several distinct varieties of the mineral according to com-
position and manner of crystallization. These are : Orthoclase,
or Potash feldspar; Oligoclase, or Soda-lime feldspar; Albite,
or Soda feldspar ; and Labradorite, or Lime-soda feldspar. The
feldspars are one of the most frequent constituents of many
common rocks, and form also the chief material for the natural
production of kaolin.

Zeolites embrace an extensive group of non-magnesian,
hydrous silicates, closely resembling the feldspars and also
nearly akin to the Augites. They may be colorless, white,
gray, reddish or flesh-colored; and contain a great deal of

CLASSIFICATION AND COMPOSITION OF ROCKS. 63

water, even 20^. They are easily decomposed by the weaker
acids.

AUGITE and Amphibole or Hornblende group. In these
minerals the SiO, is combined with magnesium, calcium, iron,
and manganese instead of the alumina and alkalies of the pre-
ceding forms. The Augitc is usually black and glassy, and but
slightly or not at all attacked by acids. It is a compound of
SiOj with lime, magnesia and iron protoxide, in which alkalies
wholly disappear. A notable feature of the mineral is the not
infrequent presence of considerable quantities of phosphoric
anhydride (phosphoric acid, P^O^). Amphibole or Hornblende
may consist of silicate of alumina and magnesia, or a silicate
of alumina and lime. The first is black or black-green ; the
latter is brown to black.

Mica consists of silicates of alumina with potassium, mag-
nesium, calcium, iron and manganese ; and is an exceedingly
abundant mineral, occurring, as it does, in almost every variety
of rock. In color it is silver-white, gray, blue-green or brown,
yellow and black. Its peculiar characteristic is the ease with
which it splits or separates into layers of marvellous thinness.
A distinction is drawn between potassium and magnesium
mica ; the latter, aside from its obvious difference in chemical
composition, being harder and nearly black in color.

Talc is a silicate of magnesia, containing traces of iron
protoxide and alumina. It possesses a peculiar fatty feel, is
very soft, and in its massive state is known as soapstone.

Serpentine possesses a composition identical with that of
talc, except that the magnesia of the former is usually replaced
in part by iron-protoxide, and it is green in color.

Olivine occurs as small round spots in basaltic and other
eruptive stones. It consists of silicate of magnesia and a vary-
ing proportion of silicate of protoxide of iron.

Nepheline is a whitish-gray or yellowish-gray glistening
compound of SiO^, alumina and soda; and is wholly decom-
posed by the action of hydrochloric acid (HCl).

Leucite is an anhydrous silicate of alumina and potassa,
existing chiefly in volcanic rocks. It occurs in hard, white.

64 A'OCA'S AND SOILS.

24-sided crystals formed by heat in lava, and was the mineral
in which the element potassium was discovered by Davy.

Tourmaline consists under varying circumstances of a score
of different elements, so that no definite composition can be
gi\-en it ; silicon, boron, iron, phosphorus, potassium, sodium,
lithium, calcium, magnesium, fluorine, manganese and alumin-
ium, at times being present in it. The mineral is of a variable
black, green, and red color, usually very dark, however. It is
an essential ingredient of shorl, and often occurs in granite,
forming beautiful columnar crystals.

Iron Minerals. Many compounds of iron occur as con-
stituents of mineral varieties, or form the mass of rock-for-
mations ; and play an important role in the decomposition of
rocks and the resulting formation of soils. These are : Iron
spar, carbonate of iron ; Red Iron stone, iron oxide ; Brown
Iron stone, iron oxyhydrate ; and Iron Pyrites, or bisulphide of
iron (FeSj).

Apatite is a native phosphate of lime, usually combined
with some chlorine and fluorine, besides occasional other in-
gredients, as, for instance, the compact earthy variety known
as phosphorite. The mineral is crystalline, usually green or
yellowish ; but in Norway a pinkish variety exists. With the
exception of phosphorite, the Apatite minerals all form more
or less beautiful crystalline masses.

Calcitk, or carbonate of lime, is very widely distributed
throughout nature, forming in its different amorphous forms
marble, chalk, coral and the very great number of limestone
varieties.

Magnesite is the native carbonate of magnesia, but is of
comparative rarity, though closely resembling crystalline cal-
cite.

Dolomite consists of a union of the carbonates of magnesia
and lime in vai;4dble proportions. It is crystalline, and ex-
ists in many so-called marbles, besides being widely distributed
of itself, and occurring as an ingredient of hornblende and some ;
augite rocks.

Gypsum, or hydrous sulphate of lime, has many characteristTcs
akin to those of dolomite. It is very abundant and soluble,

CLASSIFICATION AND COMPOSITION OF ROCKS. 65

and exists in most agricultural soils; ground, it is the so-called
"land plaster," and, burned till its water of crystallization is
expelled, it becomes the "plaster of Paris" of the arts. It is
never a component part of crystallinic rocks; but some of the
varieties, as alabaster, are susceptible of a most beautiful polish.
Rock Salt, or sodium chloride, is one of the most abun-
dant of all minerals, existing not only in the solid or rock form,
but also, from its unusual solubility in water, existing in most
mineral springs, and forming the chief mass of the saline con-
stituents of salt waters.

CRYSTALLINE ROCKS (COMPOUND).

The rocks of this division are most frequently grouped into
two classes according to chemical composition, the content of
silica being the dividing factor.

Those rich in silicic anhydride (SiOj) are brought together as
Acidic rocks ; while those poor in this constituent are desig-
nated Basic rocks.

The first class, as a rule, embraces rocks of a light color,
vitreous in character, and containing large quantities of quartz.

The second class is more frequently open in texture, usually
of a dark color, contains small amounts of quartz, and corre-
spondingly large quantities of lime.

Average Composition of Acidic and Basic Rocks.

Acidic. Basic.

Silica, SiOs, 60 — So 45 — 55

Alumina, AljOs 8 — 16 10 — 20

Iron Protoxide, FeO, )

I— 15 I— 15

aOs, j

Iron Sesquioxide, Fea(

Lime, CaO I — 5 i — 10

Magnesia, MgO, o — 4 i — 6

Potash, K2O I — 6 I — 4

Soda. NajO, i — 6 i — 5

Water, H3O, o— 8 0—7

5

66 ROCA'S AND SOILS.

I. Acidic Rocks.

These consist of combinations of orthoclase, sanidin, oHgo-
clase, quartz, mica and hornblende.

Granite consists of quartz, orthoclase and mica, possessing
no appearance of cleavage; the feldspar is usually flesh-colored,
and reflects light brilliantly; the mica varies from silver-gray to
black in color, and exists in thin scales. The rock is exceed-
ingly hard and abundant, and exists both as eruptive and
metamorphic.

Syenyte consists of othoclase, oligoclase and hornblende, or,
in place of the latter, augite or mica. The rock is distinctly
grained and crystallinic.

Gneiss differs from granite in its slate-like structure, the
composition of the two rocks being the same, but the relative
quantities of the individual constituents varying. Gneiss is
quite irregular in appearance, and is known as red gneiss and
gray gneiss, and as silicious and non-silicious gneiss.

Granulite is granite or gneiss without mica. It is slaty in
texture, fine-grained, and contains frequent small garnets.

Porphyry consists of a compact mass in which orthoclase or
orthoclase and quartz in fine grains lies bedded. The ground-
mass may, or may not, contain quartz : this is true porphyry or
quartz-porphyry. The quartz-free is the so-called orthoclase-
porphyry.

Trachyte consists of rough, porous, finely-crystallinic rock,
in which larger crystals of hornblende and mica are imbedded.
The ground-mass is usually of a yellow, gray or reddish color.
It is of eruptive origin, and cleaves into thin plates.

Phonolite is composed of compact, finely-crystallinic
masses in which are imbedded hornblende, sanidin and mag-
netite. The chief mass is of a yellowish or greenish-gray color,
and separates easily into thin large tables and large pillars.
The stone possesses a remarkable resonance of sound which
gives it the name ringing-stone.

MiCA-SCHlST consists chiefly of mica, but contains much
quartz and some feldspar. On account of its mica it separates

IT"; \\ 'Wm¥¥i

ilCLLiijiJLiiiiJ * '€i

Fig. 8.— Basaltic Columns. (After Dana.) {To face page 67.)

CLASSIFICATION AND COMPOSITION OF ROCKS. 67

readily into slabs, is very schistose. Both of the micas are
usually present, but the black mica is generally most abun-
dant. The color varies from silvery to black, according to the
amount of mica present. It is metamorphic, and often crum-
bles with great ease.

Melaphvre is usually a fine-grained, compact quartz-free-
stone, consisting of feldspar, augite, olivine, magnetite and
green protoxide of iron silicate. It is dark-colored, unstratified,
but deposited in flat single layers, often occurring between the
strata of coal-deposits, and in the Permian formation.

Basalt is a dark-gray, sometimes nearly black, eruptive
stone, exceedingly hard, consisting chiefly of augite and mag-
netite ; while different varieties contain besides feldspar, nephe-
line, leucite and mica. The coarser-grained basalts are known
as doleryte, and the fine-grained as anamesyte ; while the stone
whose mass seems to the naked eye homogeneous and un-
crystalline is termed basaltite. This rock is invariably un-
stratified, but deposits of it may occur in the formations of any
age. The chief and remarkable peculiarity of the basalt is its
separation into regular 5-7-sided pillars, sometimes of enor-
mous length.

2. Basic Rocks.

These rocks consist of a union of the various feldspars with
augite, pyroxene, hornblende or mica, with the occasional pres-
ence of magnetic iron ore and olivine ; and are marked by a
total absence of quartz.

DiORYTE is a grained crystallinic mass composed of feldspar
and hornblende. There are several varieties of the stone, dis-
tinguished by being composed of hornblende poor in lime and
rich in magnesia, with oligoclase, in which lime and iron horn-
blende are united with lime feldspar.

Clay-schist is so fine-textured, that its crystallinic struc-
ture is often not visible to the naked eye. It is generally
nearly black, and consists of clay combined with more or less
quartz and mica. Many clay-schists contain carbonates in their
composition; and often well-preserved organic remains are

68 ROCKS AND SOILS.

present. Ordinary slates comprise the largest portion of these
rocks, the roofing slate being the best and most common ex-
ample.

ChlORITE-SCIIIST is grayish-green in color, remarkably even
and regularly stratified. It contains usually some quartz, feld-
spar, mica and talc.

Diabase is a crystal-grained stone, consisting of feldspar^
augite, chlorite and titanic iron. It is quartz-free, though a
so called quartz-diabase is known. Calcite exists in all diabase,
and no stratification is ever present. The rock is quite abun-
dant, particularly in the so-called metamorphic formation.

Hyperyte is a granite-like stone, unstratified, and exists
chiefly in Labrador.

Granular Limestone is a nearly pure calcium carbonate,
usually coarsely crystalline. It is white, or nearly so, in color,
possesses fine lustre, assumes a beautiful polish, and is com-
monly known as warble.

y 11. Non-crystalline or Fragmental Rocks.

These are the sedimentary rocks of geologists, and are
secondary products resulting from the decomposition of erup-
tive or metamorphic rocks, and subsequent deposition from
water. They are simply consolidated beds of gravel, sand or
mud. Each part of the material forming these beds consists of
particles of pre-existing rocks, fragments of the same, altered
more or less by decomposition ; hence the term Fragmental.

Conglomerate is composed of fragments of crystalline
rocks imbedded in calcareous or siliceous binding material. If
the pebbles are water-worn, the product \s pudding-stone ; if
angular, the rock is called breccia.

The conglomerate varieties are numerous, varying with the
character of the pebbles and the kind of binding material.

Grit consists of hard gritty material, chiefly sand and peb-
bles. It is the " millstone-grit" of geology, so named from its
frequent use as millstones.

Tufa is invariably of volcanic origin. Volcanoes, in a state
of eruption, emit enormous quantities of scoriaceous masses

CLASSIFICATIOX AXD COMPOSITION OF ROCKS. 69

of varying sizes and called " bombs." These are accompanied
by masses of volcanic sand and ash. These materials are fre-
quently swept by the winds long distances from the point of
eruption before they are finally deposited by gravity ; having,
however, become assorted by the same force during their pas-
sage, the materials of corresponding size and weight being col-
lected together.

If, now, the material becomes deposited in water, or, as is so
often the case in volcanic eruptions, water is an accompaniment
of the action, the exuded material becomes regularly stratified,
the layers presenting various shades of yellow, gray and brown ;
and by decomposition becomes capable of sustaining vegetable
life, but never forms desirable agricultural soils.

Sand and Gravel. The former of these two communicated
materials is almost exclusively of quartz origin ; while the latter
contains in addition pebbles and stones in almost numberless
variety.

Sandstone results from the solidification of beds of sand.
They consist of particles of rock not reduced to solution by
water, but gathered together and deposited by the same, and
then solidified either by pressure or other means. Silica, being
the rock constituent, at once most abundant and most insol-
uble, forms the chief and commonest material for sand, and,
hence, for sandstone formation. The rock produced is in-
variably stratified, and not infrequently consists of nearly pure
quartz. Sandstones may also be calcareous and argillaceous.
The Connecticut River " freestone" is a sandstone containing
feldspar and glistening particles of mica.

Green-SAND is essentially a mixture of the silicates of iron
and potassium. It occurs chiefly in the Cretaceous and Ter-
tiary formations, and is a valuable manurial substance.

Clay consists chiefly of silicate of alumina. It is palpable
and plastic ; may be colored by mineral constituents either
white, yellow, red, brown or even black. It is mainly a prod-
uct of feldspathic decomposition.

Shales are rocks embracing soft, slaty, compacted siliceous
clays which by metamorphism become argillaceous slates.

Alluvium is the fineK'-dlvided earthy deposit from running

70 ROCKS AND SOILS.

waters, more especially during the time of floods. It forms
the river "bottoms" and delta formations of- proverbial fertility.

Chalk is a carbonate of lime of organic origin, consisting of
the remains of calcareous infusoria. It is the characteristic
deposit of the Cretaceous formation.

Marl consists of calcium carbonate mixed with earthy mat-
ter and often appreciable quantities of fragments of shells. It
is of considerable importance as an artificial fertilizer.

CHAPTER II.
DISINTEGRATION THROUGH INTERNAL FORCES.

Having established the important fact? of rock-composition
as related to their subsequent conversion into soils, before
tracing the chemistry of their transformation, before discussing
the changes effected by rock-decomposition, another class of
phenomena, an intermediate stage, presents itself, and demands
review, that all the steps in the geological progression whose
ultimate end is soil-production may be considered in logical
sequence, as natural law moves on from cause to effect.

The surface of the Earth, its rocks and soils, solid land and
expanse of waters, has been, through all geological time, sub-
jected to the action of forces which have constantly modified
the surface conditions of the Earth, and finally brought it to
the form and contour in which it now exists.

These forces arc the factors of Earth Development, and their
study forms the domain of Dynamical Geology.

Volcanism in its various forms of manifestation, the action
of water, of air. and of organic life, arc the primary causes
through whose agency the present physical conditions of the
geological world have been effected.

These are the great " development forces " through the ex-
ertion of which rock-masses were formed and transformed
in obedience to natural laws.

DISINTEGRATION THROUGH INTERNAL FORCES. ?!

So far as the activity of these forces is accompanied by
direct chemical action and a resulting modification o rock-
structure is concerned, they belong to the agents of rock-
decomposition, and demand consideration among the factors
and causes of soil-formation. , j-„^4-

But their activity is not seldom of a passive or adjunct
nature, whereby the modifications of surface conditions as re-
suiting from the exertion of these forces are ^nd^rcctly the
cause of many of the phenomena of rock-disintegration.

As such, the forces belonging to the sphere of Dynamical
Geology become important factors in any consideration of the
principles of AGRICULTURAL CHEMICAL GEOLOGY.

Among the natural phenomena thus demanding attention as
indirect factors concerned in the conversion of rock-masses into
agricultural soils, those of a Volcanic,Eruptive or Thermal nature
are of paramount importance.

I. Volcanoes.

The term volcano is applied to a mountain or hill which is,
or has been, connected with the Earth's interior by means of a
canal through its centre, the external opening of the canal
being designated the crater.

According to individual structure and mode of formation,
Von Seebach divides volcanoes \nto Stratified ^x.^ Homogeneous;
the material of the former being, through successive periods ot
eruption, deposited in layers or strata; the latter having been
formed from molten material which has solidified into a homo-

eeneous solid mass.

The form and appearance of the individual volcano depends
almost entirely on the material of which it is composed Lava,
tufa and ash each resulting in cones of characteristic form and

contour. .

THEIAVACONE originates in fluid material, molten stone,
which, flowing from the crater in streams, expands over the
territory reached, forming low hills, or even terraces of regular
shape or circular banks around the point of eruption, ihis

72 A'OCKS AA'D SOILS.

form is best illustrated by Mt. Loa, Kilauea, and other Hawaii-
an volcanoes.

The tufa cone owes its origin to the eruption of tufa, ash
and sand, mixed usually with hot water. The pulpy mass
thus formed rises in rings or circular waves around the crater,
flows over the sides and gradually rears a cone around the
crater, which latter attains a shallow, basin-like form.

The ash and sand cone is formed from the fine impalpable
material thrown from the crater often to considerable height,
and which, by falling back near its point of exit, builds up
around the crater a cone of dry, pulverized, volcanic debris,
consisting of ash, sand and lapilli. The material becomes ar-
ranged by gravity, so that it forms a well-stratified formation,
the fine and coarse material following each other in successive
layers.

Volcanic action is not confined to the land alone ; but may
exist beneath the sea, or may bring into existence islands
which are formed above the waves in a single night, and be-
come permanent abodes, with final formation of soil from the
decomposed eruptive matter. The island of Santorin in the
Grecian Archipelago having had such an origin in the year
1866.

A noteworthy characteristic of the stratified volcanoes is the
fact of their almost universal location in the near vicinity of salt
water. The chief of such volcanoes all being situated either on
islands or along the coast of continents, facts which point to
the sea as the source of the water which gives character to their
phenomena.

The Conditions and Causes of Eruption may be traced
to a chemical origin.

The heat of the Earth's interior is such that not only are all
the elements of which the solid earth is formed reduced to a
state of fusion, but the temperature is sufificient to decompose
many inorganic compounds, and to reduce the constituents to
a gaseous state.

The craters of most active volcanoes, therefore, while in a
state of quiet, become filled with the gases thus evolved:
l:ydrogen, chlorine, sulphur-dioxide, sulphurous acid, hydrogen-

DISINTEGRATION THROUGH INTERNAL FORCES. 73

chloride, sulphuric acid, carbonic acid, boracic acid, and, above
all, hydrogen-oxide gas, or steam.

These gaseous substances are all explosive compounds under
confinement, and mixtures of certain of them are of themselves
violently explosive, hydrogen with chlorine and hydrogen with
oxygen being among the most powerful explosives known to
chemical science ; the former exploding violently by the action
of sunlight, the latter in the presence of heat.

Others of these compounds are combustible or inflammable,
as hydrogen and hydrogen sulphide.

If, now, the explosive gases become ignited or the gas-pro-
duction abnormally increases, or, more powerful yet, if the
crater has become closed through the solidification of lava, the
accumulated and confined force within breaks through all
barriers, and the volcano enters upon a state of activity more
or less protracted as the accumulated force is great or limited.

Two immediate causes for the final eruption of lava, ash and
gas are recognized, each of which may result in eruptive action
independently, or both may combine as the factors producing
a given outburst.

First, the gradual but constant cooling of the earth's surface
is accompanied of necessity by a corresponding contraction of
mass. This contraction naturally forces the fluid contents of
the Earth's interior into such crevices as are open to them,
where they either solidify as eruptive veins, or burst forth in
the form and with the phenomena of a volcanic eruption.

Second, and more important both through frequency and
magnitude of results, is the eruption in which water is the
prime factor.

Notice has already been drawn to the fact that the chief
active volcanoes of the Earth are situated in close proximity to
the great oceans. Sea-water has access to the crevices of the
Earth's surface, and enters the pores of the world's great rock-
mass. Impelled both by gravity and capillarity, it works its
way gradually downwards, forced deeper and deeper by the in-
creasing weight of the pressing water-mass above, till finally
the region of constant fusion is reached.

Here the enormous pressure to which it is subjected prevents

♦X

74 ROCKS AND SOILS.

a conversion into gas, evaporation and steam-formation are
impossible, and the water is forced to unite with the molten
mineral matter and form a magma.

This mixture is forced, either by its own expansion or by the
Earth's contractive pressure, upwards into every gallery or
crevice of the inner surface, and rising surface-wards, explodes
immediately on gaining an altitude at which the pressure be-
comes sufficiently reduced to permit the conversion of water
into steam. Ash, lapilli and bombs fly heavenward through
the opening or crater ; the Earth quivers and trembles with the
recoil ; gases in stifling clouds roll upward ; the molten
minerals of the magma flow from the fissures ; and the volcano
is in a condition of active eruption.

The final outburst or eruption is preceded by quiverings and
tremblings of the Earth with the efforts of the pent-up force
within to find vent ; deep rumblings and rollings like subterra-
nean thunder ensue ; explosion follows explosion with increas-
ing rapidity ; the snow melts from the lofty summit ; the moun-
tain streams and springs become dry ; the seething lava in the
crater bubbles higher and higher, and finally bursts over the
crater-walls, and flows, a glowing burning mass, down the moun-
tain-sides. A pillar of smoke rises over the cone ; clouds of
ashes darken the heavens ; masses of red-hot rock, lapilli, are
thrown aloft ; and flashes of lightning dart from the electric
charged pillar of smoke, followed by peals of thunder. The
gases forming the column of vapor rising from the crater, the
pinie, may become ignited, and tower, a pillar of fire, over the
doomed region below.

The eruption may be accompanied by an outpouring of wa-
ters, resulting in the precipitation of showers of sand and ash,
darkening the heavens, and not seldom floating hundreds of
miles before finding a final resting-place.

The lava stream begins its flow after the tremblings, ex-
plosions, quakings, lapilli, and showers of ash and sand have
reached their height ; and with the outflow of lava, the violence
of the eruption ceases; relief for the pent-up forces within is
gained, and the period of normal activity sets in. The molten
stream rolls over the crest of the crater, or pours through crev-

DISINTEGRATION THROUGH INTERNAL FORCES. 75

ices opened for its exit in the mountain-sides, and often ex-
pands into extensive fields, where it cools in dense undulating
masses ; successive eruptions building rock-accumulations pile
on pile in picturesque and rugged grandeur, to await the slow
disintegration of time.*

The craters of the larger volcanoes seldom emit lava, but from
them gases and volcanic dust are poured forth in stifling clouds ;
while the molten material finds exit through fissures lower down
the mountain-cone.

The duration of lava-flow is seldom very protracted, though
in isolated instances the outflow has continued for more than
two years.f

The rate of motion, also, may vary from glacier-like slow-
ness to avalanche precipitancy, depending for rapidity on den-
sity and surface incline.

The thickness or depth of the moving stream is most usually
measured by inches, but frequently rolls on, a devastating, over-
whelming scorifying flood many feet in depth, cooling but grad-
ually, and often possessing a molten interior years after all on-
ward flow has ceased ; and even after vegetation has gained a
footing on the cooled and disintegrated surface.

Rock Transformation and Decomposition are frequent
and normal results of volcanic action. We have seen that wa-
ter-gas:{: is not the only gaseous product of volcanic action.
The sodium chloride and other components of sea-water be-
come decomposed into their gaseous constituents, but these
even are not all.

It is commonly believed that the molten interior of the Earth
consists of a magma permeated by hydrogen, oxygen, nitrogen
and chlorine, accompanied by sulphur and carbon in large quan-
tities, in the presence of all the mineral ingredients of rocks

* The ascent of Vesuvius presents most forcible illustration of the peculiar phe-
nomena, the products of successive eruption, in ail the stages between hot lava
and decomposed rock supporting advanced vegetable growth, abounding.

f Credner, Eknicntc di'r Geologic, p. 162.

\ The author takes the liberty of introducing this word as the equivalent of the
German Wasserdampf, for which neither steam nor water-vapor is a synonym, not
being a gas, but having already undergone condensation and precipitation.

"J^ ROCKS AND SOILS.

and the water-vapor absorbed at the original condensation of
the cosmic ncbuhi.

By decrease in pressure these gaseous substances expand or
explode, and are forced into the outer world, accompanied by
all the phenomena of volcanic eruption ; or may quietly escape
through fissures in the Earth's surface existing in volcanic
regions.

The hydrogen sulphide and sulphurous acid, on gaining ac-
cess to atmospheric oxygen, become oxidized into sulphuric
acid, the most powerful of mineral acids, which attacks the
silicic-acid compounds, and combining with the bases present,
forms multitudinous new compounds from every rock-mass
with whicii it comes in contact.

Eruptive rocks, thus acted on, lose their dark color, their
density, tenacity and hardness, being finally transformed into
porous, easily-disintegrated tufa or clay-like compounds.

The more common products of the action of volcanic vapors
on rock-forms are alum, sulphate of iron, and calcium sulphate
or gypsum, including the variety alabaster.

It thus appears that volcanic action not only results in the
extensive formation of new rock material which becomes in
time by natural disintegration capable of furnishing vegetable
nutriment, but the volcano, thus adding to the mass of unde-
composed rock of the earth, contains within itself the very
agents required for the decomposition of the same, and fur-
nishes the means for the chemical transformation and ultimate
decomposition of every rock subjected to its action ; thus becom-
ing an active agent in the process of soil-formation, and the
conversion of insoluble mineral matter into direct plant-food.

II. Thermal Waters.

Hot Springs are widely distributed over the earth, particu-
larly in volcanic regions ; still they not infrequently occur far
removed from the scene of active volcanic action, especially
along extensive lines of fault.

Their temperature is generally due to volcanic origin, but
also frequently owes its cause to the depth of its source. It

DISINTEGRATIOA' TIIKOUGII INTERNAL FORCES. 7/

has been experimentally determined that the temperature of
the Earth increases l° C. for every 33 m. of descent from the
surface. It therefore follows that all waters of subterranean
origin below a depth of 3300 m. must be heated to their boiling
point of 100° C.

Hot springs consist only occasionally of pure waters, from
the fact of the greater dissolving power of hot water than of
cold. The springs are therefore mineral in character. The
greater part of the famous medicinal waters of Europe are of a
medium-high temperature.

The most abundant mineral constituents of such springs are
compounds of carbonic and silicic acid and chlorine, with calci-
um, magnesium and sodium. Sulphates are usually present
if the waters exist in volcanic regions.

The outlets of these subterranean streams are, from the pres-
ence of these mineral compounds, usually surrounded by de-
posits ot carbonates, silicates and hydrates; the silicious depos-
its, in particular, often forming high walls around the place of
outlet. The amount of mineral matter thvs dissolved from the
rocks, with w^hich the waters come in contact, and deposited
along the external courses of the springs, is enormous. One
illustration will be convincing.

The famous Carlsbad hot spring is estimated to deposit an
annual burden of 2500 kg. of calcium fluoride, 600,000 kg. of
sodium carbonate, 11,000,000 kg. of sodium sulphate, besides
vast amounts of calcium carbonate and sodium chloride.*

Geysers are the form of thermal waters producing phenom-
ena of greatest magnitude, and of interest proportional to the
singularity of their nature.

They are intermittent in action ; and the columns of water
thrown from them are not infrequently forced upward more
than a hundred feet, to descend in clouds of steaming spray.

The chief geyser regions of the world are in Iceland, New
Zealand, and the Yellowstone Park in the United States ;
while other countries furnish many isolated individual geysers,
Japan possessing a numerous representation.

Credner, pp. 171-2.

78 A'OCA'S A\D SOILS.

The chief geyser of Iceland is that of Hckla. Its outlet is
surrounded by silicious deposits which have reared a mound
32 feet high and 215 in diameter. In the centre of the dome
thus formed, a basin 7 feet in depth and 60 feet in diameter
exists, into the bottom of which opens a channel 10 feet in di-
ameter and of fathomless depth.

The water of the basin varies in temperature from 76°-89° C,
but increases in the channel till at a depth of 98 feet a tem-
perature 27° C. above the boiling-point is recorded.

The intervals between the periods of activity vary from 24
to 30 hours ; and the final outburst is supposed to be due to
causes simiLr to those resulting in volcanic eruptions.

At the depth at which vaporization of the water would be
possible, that is, the depth at which the water temperature
reaches 100° C, the pressure of the enormous column of water
prevents all conversion into vapor, and no overflow is possible.

But the heat of the superheated liquid radiates gradually
into the cooler waters above till they reach the vapor-point,
when an explosion occurs, resulting in throwing the immense
volume ot water 120 or more feet into the air. Falling back
into the basin, the enclosed waters are again cooled below the
boiling ^ oint, and the process begins anew, to repeat itself again
after each lapse of 24 or more hours.

The American National Park abounds in geysers of unsur-
passed grandeur and magnitude, in keeping with the wonderful
phenomen:: for which the region is renowned.

Streams of hot water and a boiling lake add to the magni-
tude of the thermal phenomena presented. The total number
of active geysers is probably not less than one hundred. Of
these the Beehive, the Gian:, White Mountain and Old Reliable
are the most noteworthy. The first-named seldom experiences
activity oftener than every third day; but is violent in action,
and forces its mammoth fountain spray 140 feet high. The
last-named is active at intervals of less than an hour, and
throws its mighty column as high as its neighbor, but with less
accompaniment of steam, spray and explosion.

The Rock decomposition resultinii from thermal action

DISINTEGRATION IH ROUGH INTERNAL FORCES. 79

is of a nature identical with that recorded as resulting from
volcanic eruptions, and needs no further comment.

The industrial importance of thermal waters as sources of
heat and power is just beginning to receive recognition.

The city of Baden-Baden has long been supplied with hot
water conducted from its famous springs to all parts of the
town for domestic and economical use. And the capital of
Hungary, Buda-Pesth, is even now successfully experimenting
with the bold project of supplying its houses and factories with
water, heat and power extracted from the Earth's interior in the
form of thermal waters artificially confined, and brought into
service.

III. Contraction of the Earth's Surface.

Any force or natural phenomenon resulting in the changing
of surface conditions, the rupture of strata or rearrangement of
strata relations, becomes of direct importance as a producer or
abettor of rock-transformation and disintegration.

Among the occurrences of this nature, and therefore de-
manding consideration, changes of surface level, mountain for-
mation, and earthquake actioii are of chief significance, and the
origin of all may be traced directly to the contraction of the
Earth's surface resulting from the gradual reduction of temper-
ture through radiation of heat and consequent cooling.

A. GRADUAL CHANGES OF SURFACE LEVEL.

Firm and inelastic as the solid Earth's surface may casually
appear, many portions of it covering extensive areas are still
gradually undergoing either elevation or depression of level.

The movement is usually so slight, or is extended over geo-
logical periods of time so great, that the fact of change of level
would be difficult of determination, did not the sea-level ofYer
a permanent standard or base for comparison.

The phenomena thus made apparent embrace occurrences of
almost universal extent and significance.

Sea cliffs and beaches buried beneath the waters of former
times are found to-day high and dry above the tide. Harbors

80 KOCKS AND SOILS.

become useless through shallowing because of elevation of bot-
toms. Coast-lines creep gradually out to sea. Coral forma-
tions are laid bare ; and shores of ocean and fresh water alike
gradually disappear beneath the flood, bearing into the waters
the relics of the time of sinking for the enlightenment of com-
ing ages.

Elevation of Surface finds its most striking and best-
known illustration in the Scandinavian peninsula, the coast of
which has not yet gained a final equilibrium since tlie disturb-
ances to which it was subjected during the Cenozoic time.

Norway presents tide-water markings on the sides of cliffs,
and deposits of marine fossils of recent origin from 400 to 500
feet above the present sea-level. The most vivid presentation
of the phenomena existing in the neighborhood of Tronhdjem,
while in the vicinity of Christiania, terraces and beaches of
water-washed sand exist at an elevation of more than 600 feet.
The force which thus reared a great expanse of territory several
hundreds of feet above its former level is still at work, and its
progress is recorded by the National Geological Survey of
Sweden and Norway.

The occurrences in Scandinavia find corresponding phenom-
ena in Scotland and Chili. In the former country the so-
called " raised beaches " exist 30 feet above the sea, and extend
often for many miles along the coast ; presenting not only
recent fossils, but well-preserved relics of man's existence in
the form of canoes and implements of stone.*

In Chili the elevation of the coast region is still making ap-
preciable progress, and is doubtless one of the causes resulting
in the formation of the deposits of nitrate of soda (Chili salt-
petre), to which, perhaps, more than to any other cause the
country owes its prosperity.

Depression of Surface is an occurrence of far greater dif-
ficulty in establishing, owing to the lack of standards of com-
parison of level through disappearance of surface beneath the
sea. Yet though the rate of disappearance is hard to deter-
mine, abundant evidence of such action is brought to notice.

* Lyell, " Antiquity of Man," p. 60.

Fig. q.— Sea-terraces of Norway, showing elevation of land. (After Geikie.)

( To face page 80.)

DISINTEGRATION THROUGH INTERNAL FORCES. 8l

Beneath the waters of sea or lake, coral-banks, peat-beds,
forests and human habitations, are either seen to disappear, or
are discovered long years after they were engulfed by the
waves. The amber-producing forests ot the North Sea and the
lake dwellings of Switzerland offering most forcible illustration
of the fact.

Coast regions of England, of France, and of North America
from New Jersey to the Gulf of Mexico, the southern part of
Greenland, and the North Sea coast of Germany, are gradually,
but constantly, being buried beneath the waters of the ocean.

The ruin of the temple of Jupiter Serapis on the Bay of
Naples offers an example not only of sinking of surface level
but of subsequen^t re-elevation. The once noble structure pre-
sents to present view a marble pile from which three superb
pillars tower 37 feet above their base. The upper and lower
sections of the columns retain their marble lustre and polish ;
but midway of their height a space about 4 feet in length pos-
sesses a surface water-worn and burrowed by boring mollusks
whose remains still exist imbedded in the stone.

Evidence is thus furnished to establish the fact that, since
the temple was reared, long since the era of authentic history
began, the Italian coast in the vicinity of Vesuvius must have
sunk some eight feet in level, and have thus remained while
the mollusks retained in the Serapis columns did their histori-
cal work ; after which a period of elevation set in, and contin-
ued till the pillars were raised to the position they to-day
occupy.

The Changes of Level during former Geological
TIMES accomplished results in comparison with which the oc-
currences of to-day are insignificant indeed ; yet there is no
evidence that the rate of activity was greater then than now ;
for the duration of our present observation is as infinitesimal,
as compared with the whole lapse of time of even one age of
geological history, as the phenomena we witness are unimpor-
tant when compared with similar disturbances of past times.

The greater part of all continents was once the bed of
oceans, from the waters of which the sedimentary deposits

4

82 ROCKS AND SOILS.

were laid down, and above which they were afterwards forced
by gradual elevation.

Not only is the origin of continents directly traceable to this
lifting movement, but whole continents are supposed to have,
by the reverse process, been engulfed in the waters, leaving
archipelagoes to mark this former location of continents.

An explanation is here presented for the occurrence in cer-
tain islands, as for instance in New Zealand and Australia,* of
animal and plant forms long since extinct on the continents
from which they are separated by expanse of ocean, connection
with foreign fauna and flora, with their modifying influences,
being thus removed.

The frequent similarity of life existing in islands now far dis-
tant from each other also furnishes presumptive evidence, con-
firmed by geological features and ocean soundings, that the
now isolated isles once formed the mountain summits of great
continents at present covered by fathoms of water.

B. MOUNTAIN FORMATION.

The accepted belief as to the causes to which the great

mountain chains of the Earth owe their origin has undergone a

radical change during the present generation. Formerly the

belief was universally held that mountains were the result of

^/'■.\ volcanic action, or of

.^-. .-.(I^V/ix, , exertion of pressure

;>^>' , . /I '■ ^ .T^^zy^''^^;^,^,,,,^ >^-.| from within the

TT M °.- c ' .■ r. CI .u u u AH \' Earth, exerting^ itself

Fig. io.— Mountain Formation. Profile through the Allegha- ' <^

nies. I, Miocene; 2, Eocene; 3, Chalk; 4. NewRedSandstone: upward and rearing
5, Carboniferous; 6, Devonian; 7, Siluriiin; 8, Primary Gneiss ,1 i^ ■ 1 , 1

the mountains by the
force of its upheaval. But a new theor}' has become the ac-
cepted belief of the present day, owing to the unimpeachable
evidence of facts irresistibly presented by Heim, Suess and Dana.

The process of mountain formation is simply the
folding or wrinkling of the thin Earth-surface, following the
continued cooling and resulting contraction of the same.

The rock-stratifications of the Earth are easily traced through

* Though Australia is now considered a continent, its isolated position geo-
graphically and geologically favor the former designation, island.

DISIXTEGRATIOX THROUGH INTERNAL FORCES. 83

all their convolutions ; and when they form chains of mountains,
their original extent when lying in flat level layers on the
Earth's surface can be determined beyond hazard of doubt; and
they are proved to have originally occupied an area far greater
than that into which they have been forced or shoved by de-
crease in dimensions of the Earth-mass. The decrease of surface
can only be explained by the fact of contraction through cooling.

The flexibility of rock-masses which thus allowed
themselves to be beset and folded with only occasional breaks
or faults is traceable to two causes. First, the movement may
not have extended through the entire mass as a unit, but the
pressure applied may have reduced the rock affected to the
finest compact particles which, forced from the position for-
merly occupied, assumed new directiotis of stratification, in which
position they became again aggregated, and exist as the folds
and convolutions of mountain strata.

Second, no solid is so dense that it is insensible to pressure,
and cannot be bent or flexed, if the force be great and exerted
through periods of sufficient duration. A result more readily
accomplished with rocks, if, as claimed by Heim, the molecular
condition of the rocks of mountain-making ages was different
from that they to-day present — if they were, in fact, plastic in
nature — a condition in which much of the deep rock-mass of
the Earth must still exist, and to which either heat or pressure
is capable of again reducing both rock and mineral.*

Though the force thus exerted through contraction caused
the most lofty mountains to rear their peaks above the sur-
rounding plain, and compelled the rocks to wrinkle and fold on
themselves, the tension was often too great or the contraction
too rapid to allow the strata to readjust themselves without
parting. Faults and fractures thus resulted, by whose presence
the disintegrating forces of nature are abetted and aided in their
labor of rock-disintegration.

* Prof. Spring succeeded in reducing filings of bismuth, tin, zinc, aluminium,
copper, antimony and platinum to solid metallic blocks, microscopically identical
with wrought metal, at a pressure of 2000-6000 atmospheres; and at 5000 at-
mospheres tin and aluminium flowed in liquid form from the apparatus. (Credner,
p. l^C); Jalirhuch fur Mincralor:;ic. 1882, p. 42.)

84 ROCKS AND SOILS.

Continent Formation is a grand and direct result of this
surface contraction and mountain-formation phenomena.

The Earth-crust by contraction of mass through coohng be-
came too large for its nucleus, and the superabundance of sur-
face was absorbed in the folds of mountain-chains ; but the
wrinkles thus formed consisted of necessity of both elevations
and depressions. Into the latter or lowest portions of the globe
the waters collected on its surface became gathered into
oceans, while the elevated land thus left dry forms the conti-
nents of to-day, the coasts of which are parallel with the great
mountain-chains resulting from a continuation of the same uni-
versal contraction.

C. EARTHQUAKES.

Mountain formation as a result of surface contraction is, so
far as visible or actual existence of present phenomena are con-
cerned, an occurrence of past geologic times. A phenome-
non of similar nature, however, resulting from identical causes,
and followed by the same effects on the rock-strata of the
surface, and very probably the present evidence of mountain
growth whose complete results must be deferred for coming
ages of geological activity, is presented in the earthquake
action of such universal occurrence during this and former
times.

True, no phenomena of nature present fewer definitely un-
derstood and generally accepted facts than the occurrences
classed under the term '' Earthquake ;" and none have been
surrounded by greater dread and superstition, or have been the
subject of more futile attempts to reduce their causes to the
limits of forces acting under and controlled by known natural
laws.

True, also, that a large proportion of the earthquake action
of modern times is directly traceable to a volcanic origin,
With this latter form we are not concerned further than to re-
peat the brief statement made in connection with volcanic ac-
tion. The occurrences of this nature are, however, but an in-
significant portion of the great number of earthquakes to which

DISIXTEGRATION THROUGH INTERNAL FORCES. 85

the Earth has been subjected during each generation of the
modern epoch.

Few geologists would hazard the assertion that all the laws
of earthquake action are yet known, and that satisfactory
causes based on natural law can be assigned for each and e\-ery
earthquake experienced ; still, a long stride towards so desira-
ble an end has been made within the present half-cent ur}-,
through the labors of Mallet, Seebach, Fuchs, Heim, and the
Seismological Society of Japan under the leadership of Prof.
Milne.

As a result of the labors of these and other workers in the
field, the vast majority of earthquake phenomena are to-day
recognized as belonging to one or the other of two forms ; and
however much opinion may vary as to the origin of a given
example of earthquake action, there is practical unanimity in
the verdict that two, and only two, causes can be assigned for
all the great earthquakes of modern times. These causes of
earthquake phenomena may be designated as Surface Contrac-
tion and Subterranean Explosion.

Phenomena whose origin is referred to the former cause con-
stitute the so-called DISLOCATION Earthquakes, and are a
mere continuation of the occurrences resulting in the mountain-
ranges whose structure we have already reviewed.

In reality these earthquakes are simply the sensible effects of
the breaking of rock strata, or the forward movement of one
rock-formation over or on another. The shock is only the jar
resulting from inertia or from friction, the magnitude of results
depending on area or extent of rock moved and the distance of
fall or forward movement.

The force or power exerted is simply the irresistible force of
contraction through cooling b}' continued radiation of heat.

The nature of such phenomena will be most satisfactorily
understood by reviewing a typical earthquake of such recent
occurrence as still to be fresh in recollection. Such an example
is furnished by the Charleston Earthquake of August 31, 1886.

Mention has already been made of the fact that the eastern
coast of North America from New Jersey to the Gulf of Mexico
is now undercfoine a ci'adual sinking.

86 A'OCICS AND SOILS.

This depression of surface extends inland from one hundred
to two hundred miles, and is bordered westward by the line of
fracture of the continent. This region has, during former
geological ages, undergone many changes of level, now moving
up, now moving down. The present period of depression can-
not, from the nature of the geological conditions, be permanent,
but changes of level must continue to take place for ages to
come.

The line of fracture, the interior limit of movement, may
again become, as in former times it was, the continental coast-
line, or the coast may continue to advance seawards a hundred
miles beyond its present position.

While this condition of instability continues, the Atlantic
coast region cannot escape surface agitation ; and the move-
ment may at long intervals attain the force of an earthquake.

This was doubtless the real event that was attended with
such disastrous consequences in South Carolina; all the cir-
cumstances of the event, both local and extensive, point to this
one solution, and the shock was k geological dislocation.

The second, or Explosion Earthquake, through having
origin in the sudden liberation of an explosive force within the
subterranean depths, or beneath the surface formation of the
earth, presents phenomena not so easily or satisfactorily ac-
counted for. The fact of explosion is not doubted, but the
immediate cause of the explosion is accounted for in various
ways.

This class of earthquake action is practically confined to
regions of volcanic origin ; but the volcanoes are more probably
another result of the same cause to which the earthquakes are
due, than themselves being either directly or indirectly the
actual cause.

Attention has already been drawn to the fact that the tem-
perature of the Earth regularly increases with the depth from
the surface, till at 3300 metres the boiling-point of water is sup-
posed to exist. We have also seen that the .waters of the
surface permeate the rock-mass and through capillary action
may descend to any depth, but the pressure exerted will pre-
vent the evaporation of this water at ioo° C, and a temperature

DISINTEGRATION THROUGH INTERNAL FORCES. 8/

sufficient to decompose water into its component elements,
hydrogen and oxygen, might be attained. At a certain depth,
also, the capillary attraction would be overcome by heat ; and
at this depth, when the waters could penetrate no farther, an
equilibrium would be established between the waters as vapors
and the heated rock, — a delicate equilibrium easily disturbed,
either by movement in the mass or by addition of more water
from the surface ; and then an explosion occurs, either of vapors
formed, or by the sudden transformation of water into vapor,
and the shock of the explosion felt at the surface is called an
earthquake.

Such is, doubtless, the origin of the earthquakes of volcanic
regions, and particularly of the majority of the annual average
of sixty earthquakes in Japan.

The Relation between Earthquakes and the Geo-
logical Structure of the Affected Region is most inti-
mate; indeed earthquakes are distinctly geological phenomena,
all depending on geological causes for the character of their
action ; and many, as we have seen, resulting from movements
of rock-formations.

There are also local phenomena of a more distinctly geologi-
cal character still, to which reference was made on page 25.
But whatever may have been the cause of a given shock, its
intensity and duration are chiefly controlled by the nature of
the rock-formations beneath which the force is exerted.

The force of an individual shock varies with the density of
the rock-mass agamst which it is exerted. It follows, therefore,
that regions of massive unstratified rock are least affected ; that
in regions of sedimentary formation the movement does not
proceed regularly in all directions, but follows the course or
direction of stratification.

The greatest severity of shock is experienced with conjunc-
tion of loose porous deposits on a massive solid sub-formation ;
and the most effective geological protection against severity of
shock is presented by fractures and faults interposed to break
the continuity of the earthquake wave. Facts experimentally
demonstrated on the largest and most significant scale by the
great disaster whose centre fell in the vicinity of Charleston, a

88 A' OCA'S AXD SOILS.

region of porous, often sandy, structure, bedded on massive and
older rocks, and confined within the area bounded by the great
fault of the " Piedmont Escarpment."

The Systematic Observation of earthquake action is
chiefly based on accurate records of the time of arrival of indi-
vidual shocks and the duration of the same, together with the
direction and angle of the display of the force as exerted against
different objects. The rate of motion and direction of move-
ment, together with the angle at which tne torce was exerted
against a given structure, being thus determined, data are at
hand for establishing the " centrum " or place of origin of the
shock ; and the fact seems already established that earthquake
origin is at a comparatively slight distance from the Earth's
surface, being found at from 17,260 to 127,309 feet toward the
Earth's interior.* The force thus exerted appears, therefore,
in the vast majority of shocks of the explosive character, to be
not greater than is compatible with the theory of origin.
Chemical explosions often communicate shocks through areas
several miles in extent, while it is hardly possible that the
slightest movement or motion in a mass so enormous and of
such weight as the rock-strata of the Earth, even to a depth of
a single mile, should fail to be followed by shocks equal in
severity to the greatest earthquake phenomena of history.

IV. Rock-metamorphism.

By the term victmnorpJiisvi a very important fact as related
to rock-decomposition is designated. The word implies any
change either in the texture or composition of the rock. It,
in reality, signifies a physical or chemical transformation either
of the rock or of its constituent minerals. By the action thus
described, the great geological class of metamorphic rocks,
rocks of crystalline structure, was brought into existence.
Sedimentary sandstones, shales, conglomerates and limestones
have thus been transformed into slate, mica-schist, gneiss,
granite and marble.

* Milne, "Earthquakes" (London, 1886), p. 214.

DISINTEGRATIOX THROUGH INTERNAL FORCES. 89

The transition from one form to the other is, however,
exceedingly gradual, and no definite line of demarcation can be
drawn between the changed and unchanged rocks, the sedi-
mentary passing insensibly into the metamorphic.

The transformation thus effected in the composition or
characteristics of geological formations must assume high im-
portance among the conditions indirectly influencing or con-
trolling the subsequent rock-transformation by decomposition
or disintegration, as the results accomplished by the forces
engaged in the latter processes are controlled no less by physi-
cal conditions than by chemical composition of the rock form
against which they are compelled to act.

The causes chiefly responsible for this metamorphism or
alteration of rocks are these : Pressure, Heat, Moisture,
Chemical Affinity.

Mctaviorphisvi by Pressure alone has, doubtless, been a fre-
quent consequence of geological activity, yet it is hardly proba-
ble that the transformation could have thus resulted were it
not for the fact that the pressure exerted is the cause of an
extraordinary elevation in temperature, followed by crystalli-
zation of the rock-mass affected.

The transformation thus produced is known as Techtonic
MetamorpJiism ; and the fundamental cause seems to have been
the mountain formation as a result of contraction, whereby the
necessary pressure was exerted. This origin for the phenomena
seems demonstrated both by natural events and by experi-
mental facts.

The degree of crystallization in slate rocks is usually propor-
tional to the amount of disturbance which the original stratifi-
cation has undergone. In other words, the perfection of crys-
tallization or metamorphismis determined by the degree of
mountain-making force exerted. The experiments of Spring
alluded to on page 83 further demonstrate that not only is
crystallization a direct result of this pressure, but chemical
combination, as well, is produced by the same means: copper
filings and powdered sulphur uniting to form crystalline copper
sulphide, as a result of extreme pressure experimentally ap-
plied.

QO ROCKS AND SOILS.

Heat either directly or indirectly is the chief cause of rock-
metamorphism. As just demonstrated, however, heat is not
the fiindauicntal cause of the transformation, but is an accom-
paniment of the change ; still, much of the transformation of
sedimentary rocks was doubtless the direct consequence of in-
crease in temperature unaccompanied by other cause.

The source of the temperature thus active must be sought
in the internal heat of the Earth, radiating to the surface, and
exerting its transforming influence on all the sedimentary
accumulations through which it passed.

The temperature resulting in metamorphism was not of an
extremely high degree, varying from 250° C. to 650° C. The
transformation was thus produced at comparatively low tem-
peratures, but by heat acting through long eras of geological
time.

Moisture as an active agent in rock-metamorphism is estab-
lished by the fact that rocks cannot become heated without
the presence of moisture, and water is frequently found enclosed
in crystals of quartz, garnet and other mineral constituents of
metamorphic rock.

The moisture of metamorphism was for the most part derived
from the sedimentary formation on which the transformation
was performed, either filling the pores of the rocks, or existing
between strata.

Here it served, first, to increase the heat-conductivity of the
stone, which when dry is a most imperfect conductor of heat,
thus furthering and increasing the activity of the heat engaged,
and then by the action of the same heat being converted into
vapor, and becoming of itself a dissolving and decomposing
agent resulting in crystallinic transformation.

The amount of water usually present in sedimentary rocks is
not far from 3 per cent of their total composition, an amount
equalling about five pounds of water for each cubic foot of
rock. The amount of vapor thus generated was, therefore, ca-
pable of producing all the transformation that ensued.

If, moreover, as was very generally the fact, these waters
were sea-waters, they contained mineral matter, compounds of-
sodium and magnesium, with boracic, hydrochloric and phos-

DISIXTEGRATION THROUGH INTERNAL FORCES. 9I

phoric acids; which ingredients were added to the crystaUine
structure resulting from the metamorphic action.

The Hydrochemical Process of metamorphism produces
its results by the combined action of water and heat exerted
according to the laws of chemical affinity.

Bischoff, indeed, strongly advocates this as the chief or only
cause of regional metamorphism. The transformation, as he
traces it, resulted from the action of plutonic heat on the hy-
drostatic waters of the rocks. The atmospheric moisture pre-
cipitated as rain on the Earth's surface absorbs carbonic acid
and oxygen, and permeates the surface rocks.

The oxygen becomes exhausted as an oxidizing agent, while
the carbonic acid attacks the silicates and transforms them
into carbonates ; and at the same time the waters, penetrating
deeper and deeper, become finally exhausted, and all decom-
position through their agency must cease.

But the water thus saturating the rocks is a most powerful
dissolving agent ; and becomes laden with dissolved mineral
matter, \\hich in the deeper regions becomes active for rock-
transformation by decomposition and recombination. The
transformations thus occurring are chiefly the result of combi-
nation of the soluble alkaline and calcium silicates with alu-
minium and magnesian silicates, principally mica and feldspar,
which, in time, become crystalline.

The principal obstacle to the extensive action of this process
of metamorphism lies in the exceeding great lapse of geological
time required for the completion of the process by water satu-
ration of the rocks existing now in transformed strata.

The chemical decomposition and transformation produced
was doubtless increased and hastened by a degree of heat capa-
ble of converting water present into superheated vapor, a most
powerful solvent and destroyer of cohesion. All silicious min-
erals are by the decomposing action of such heated vapor
themselves vaporized, and on condensation form crystals of
quartz, feldspar, mica, zeolites, pyroxene, and other silicious
minerals.

These are but constituents of the most abundant metamor-
phic rocks: granite, gneiss and crystallinic schists, with the

92 ROCK'S AND SOILS.

vast series of transformed sedimentary formations thus being
possible results of the presence and action of the heated vapors
of water.

The degree of heat and amount of moisture present were
doubtless the controlling factors in determining the character
of the metamorphic change. For instance, excess of moisture
would produce hydrous rocks, like chloritic schist, while a
greater degree of heat, or less moisture, would have resulted in
the formation of a hornblende schist, the only essential differ-
ence between the two being the content of moisture.

It is, therefore, apparent that sedimentary rocks, which are
most closely allied in all characteristics, may by the process of
metamorphism become transformed into varieties wholly dis-
similar, both in chemical composition and physical structure.

Pseudomorphism, the change of constituents of a mineral
without change of crystalline form, is a variety of metamor-
phism as important as it is remarkable. The pseudomorph
possesses a crystalline form foreign to its present composition ;
and this change is, therefore, wholly in its constituents, that is,
the change is chemical in nature ; and has been produced by
the dissolving power of water, whereby a mineral of comparative
insolubility has, through the lapse of ages, been reduced to so-
lution, and carried away, while in its place new material has
been deposited, and occupies the old crystalline form ; or, by
the action of water, a slow but actual transformation in con-
stituents has occurred.

This transformation may be the loss of certain constituents,
the addition of new material, or the substitution of one sub-
stance for another ; and their existence establishes the solubil-
ity of many compounds which are usually classed as insoluble
in the presence of chemical reagents. In this connection, those
products are most important which possess no chemical rela-
tion to the original minerals, illustrated by pseudomorphs of
limonite and pyrites after quartz, and of quartz after fluor-
spar.

The phenomenon of pseudomorphism is most frequently a
silicification, that is, the transformation usually results in either ~
a silicious mineral, or in the transformation of silicates.

DI SIX TEG NATION THROUGH EXTERNAL TvRCES. 93

Though the chemical substitution or reaction occurring may
be of various forms, the most abundant is a simple process of
hydration, illustrated by the conversion of pyroxene, chlorite
and other anhydrous magnesian silicates into serpentine, the
hydrous magnesian silicate.

The transformation in chemical composition, and in the char-
acteristics of minerals, through the process of pseudomorphism,
often occurs on a most extensive scale, changing the geological
formation over large areas of country, and thus furnishing an
important means of rock-metamorphism.

Large deposits of doleryte are transformed chlorite ; while a
large part of the serpentine rocks are a pseudomorph of chrys-
olite and pyroxene. Serpentine is also a product of trans-
formed apatite. But more remarkable yet is the recently-
claimed transformation of quartz into serpentine, and the fact
that the latter mineral so widely distributed is in large areas of
the Pacific coast region a pseudomorph after quartz.* It also
appears that, in the same formation, most metamorphic rocks
" are subject to serpentinization."

Pseudomorphism must, therefore, be recognized as an impor-
tant factor in the series of mineral transformations whereby
rock -characteristics are modified, rock -decomposition influ-
enced ; and the products of their disintegration controlled.

CHAPTER III.
ROCK-DISINTEGRATION THROUGH EXTERNAL FORCES.

The expression " firm as a rock," so commonly used as the
superlative of stability, must, in the light of facts reviewed in
the preceding chapter, lose all significance other than as a
mere medium of comparison.

Acted on by the forces of nature, rocks are, in reality, any-

G. F. 'B^ckRT, American Journal of Science, May 1886, p. 355.

94 A'OCA'S AXn SOILS.

thing but enduring; however much the process maybe con-
trolled or modified by the agencies already considered, the
ultimate disintegration is inevitably the result of direct chemi-
cal decomposition and transformation, the course of which as
occurring in rock, and the stages of soil-production, must next
be systematically examined.

Rock-decomposition consists of two distinct processes: first,
the mere destruction of form, or pulverization of the rock-
mass ; second, the erosion or washing away of the fragments,*

The former is chiefly effected through the chemical action of
water and air, through change of temperature and action of
organic life. The latter is accomplished through the action of
the water descending as rain, and filling the rivers and streams ;
the waters of ocean beating against shore, and of congealed
streams forming moving masses of ice.

The transformation by which soils succeed rocks in geological
progression has, therefore, been produced by the direct action
of four distinct factors, namely : change of temperature, water
and ice, air and organic life.

I. Change of Temperature.

The rock-crust of the Earth itself resulted from the cooling
of the rotating mass; and the gradual continuance of this cool-
ing process must have been followed by a concentration of
mass and contraction of surface and volume, resulting of neces-
sity in the breaking and cracking of the crust. The elevation,
subsidence, wrinkling and folding, resulting from this shrink-
age, caused the formation of sea-basins, mountain-ranges and
valleys.

The varying composition of crystalline rocks, with resulting
irregularity in expansion and contraction through the influence
of heat and cold, together with the unequal expansion and
contraction of the same crystal around different axes, were im-
portant factors in the breaking up of rock-masses and the
formation of soils. This separation of rocks into their com-

* Heim, Ueber die Verwitierung im Gebirge (1879), p 6.

DISINTEGRATION THROUGH EXTERNAL FORCES. 95

ponent crystals, and the subdivision of the crystals themselves,
is, perhaps, the most important fundamental cause for the
pulverization of the Earth's rock-mass.

The outer surfaces of rocks are very sensitive to the changes
of temperature, not only with the seasons, but from day to
night. The former is estimated to exert an influence at a
depth of from 60 to 100 feet; though the influence of the lat-
ter does not extend deeper than from 3 to 10 feet.

This variation of temperature is followed of necessity by con-
traction and expansion of surface, resulting in fracturing the
mass and rendering it more porous.

In desert lands, where the temperature from day to night not
seldom varies 60° C, boulders are often broken in pieces from
this cause alone.

But the most powerful and extensive action consequent
upon change of temperature follows the influence exerted
through the presence of moisture and a decrease in temperature
belozi' the freezing-point of water.

Water forms an exception to the rule that " bodies expand
with heat and contract with cold." The law of expansion and
contraction is, in this case, reversed when the liquid reaches
4° C, below which temperature it expands. Ice occupies,
therefore, a greater space than the water from which it was
formed. In the freezing of water, then, lies the source of irre-
sistible power, the partial confining of which in the pores and
crevices of rocks results in tearing, breaking, rending and
crumbling of the same.

This expansion of volume through the freezing of water is
equal to one fifteenth of its mass, and the power is manifested
in the splitting of enormous blocks, tons in weight ; in the
tumultuous breaking down of whole cliff-ranges, or the silent
disintegration of rock-surfaces ; the gradual crumbling away of
grain on grain, crystal from crystal, or particle by particle.

II. Action of Water.

Among all the agents of rock-disintegration, by far the most
active is water. It is the great transforming force in nature,

96, ROCK'S AND SOILS.

acting both as liquid and as solid ; and with an influence and
transforming power reacting from the tops of the highest
mountains down through all the strata of the Earth's mass to
the deepest geological structure yet aggregated from the in-
terior magma.

The entire circulation of water from the uncondensed moist-
ure floating in the atmosphere surrounding our earth, through
the precipitation in drops of rain, and passage through the
rocks and soil, or over their surface into the streams and back
again to the ocean to become re-evaporated into the air, is a
progression of geological changes, followed by constant modi-
fications of surface, and transformations in composition of the
material, against which water is made to exert its power.

Not only does water possess the advantage of being triple-
armed for the accomplishment of its work, exerting its force
as vapor, liquid or solid, but it is capable, under varying cir-
cumstances, of either mechanical or chemical action. Thus,
through all the ages of geological activity, it is to water more
than to all other agents combined that the physical and chem-
ical features of the Earth have been due : rock-formation and
rock-disintegration being alike the result of its action ; moun-
tain and valley, rock and soil, being but varying records of its
perpetual activity and all-reaching power.

A. MECHANICAL ACTIVITY OF WATER.

The transformation wrought through the physical action of
water may be described as resulting from two different proper-
ties, or really two different modes of action.

First, the effects produced by the direct abrasion or erosion
caused by a moving mass of water, the result being in reality
due to motion, water being but the agent.

Second, the action of water as a destroyer of cohesion, where-
by, through its penetrating rock-masses, the particles become
separated from each other, and the rock softened in conse-
quence, and rendered more susceptible to the disintegrating
influences to which it may be subsequently subjected.

This latter mode of action is universal in extent, and follows

DISIN r\GRATJON THROUGH EXTERNAL FORCES. gj

every instance of contact between water, either moving or sta-
tionary, and rock or soil. It is usually this action with which
the influence of water as a rock-disintegrator begins ; the sub-
sequent reduction of mineral constituents to solution, or the
results of chemical combination, being simply the final effects
of a condition first produced by loss of cohesion in the rock
attacked.

Running Waters or streams are chief among the direct
means by which the erosive, or water-friction, results of the
mechanical influence of water are produced.

The atmosphere is the medium through which the waters of
the ocean, the great reservoir, become gathered into streams
which become the chief sources of surface modification. Evap-
orated into the atmosphere, precipitated as rain or snow, gath-
ered by gravity into streams, flov/ing back to the ocean,— thus
the circulation of water through the universe goes on throuo-h
the ages, performing in its course its offices of softening, abrad-
ing, disintegrating ; consuming here, building there ; tireless, re-
sistless, ceaseless.

The amount of water thus kept in motion, and without rest
laboring against the geological structures of the Earth, is incon-
ceivably great. An annual rain-fall of three feet for all the
world becomes in one thousand years an accumulation of three
thousand feet over the surface of the globe; yet a thousand
years are but a jot as compared with the lapse of a single geo-
logical age, and an age is but a fraction of all geological time.
Still, through these periods of countless years, the activity of
this constantly-moving, ever-replenished mass of water has not
ceased. There is no wonder, then, that valleys are formed,
that cafions are grooved in solid rock, that thousands of tons of
sediment form the annual burden of innumerable streams ever
gaining fresh accessions from rains, springs and percolations.

Erosion, the wearing away of rock and soil by the action of
moving streams, has been the most active of the immediate
causes of the results attributable to water action. The term,
however, really includes chemical as well as mechanical action,
inasmuch as the results are infinitely enhanced by the action

98 ROCK'S AND SOILS.

of chemical solvents held in suspension in the waters of all
moving streams.

The mechanical action on the solid mass of the Earth is but
an illustration of the hidden force of moving water, ever exert-
ing itself against all impediments in its course, and by contin-
uous, persistent action ov^ercoming and obliterating every ob-
stacle.

The very changes of temperature resulting from modification
of level send the atmospheric moisture from the heated valleys
and plains to the cooler mountains and plateaus, where it be-
comes condensed, and, falling upon the surface, rills are formed,
rivers rise, and mighty currents sweep to the sea, leaving evi-
dences, through all the region they traverse, of water's erosive
action. Whether the force be made manifest in the form of
atmospheric moisture precipitated on rocky walls of mountain
summits, or driven by the winds through valleys and over
plains; whether it be by storm-beaten ocean rolling wave on
wave against unprotected shore, or river current washing and
undermining its overhanging banks, the result is the same, and
the ultimate end is only gauged by duration, for the force is
resistless.

The more marked the action, the greater the power for ac-
tion, the erosive force constantly increasing in ever-ascending
ratio ; for every particle of sand and or stone detached from its
mass becomes an instrument driven by water-power and worked
for the grinding and pulverizing of every solid mass with which
it comes in contact, or against which it is driven.

Every river-bed or valley, every sea-beach and every moun-
tain-side present graphic proof of this never-ceasing activity
of moving water.

Some of the most remarkable illustrations of such action are :
the isle of Helgoland in the North Sea ; the Elbe Valley near
the Bastei in Saxony; the Simeto River in Sicily, which, in
two hundred and fifty years, excavated a channel more than
fifty feet deep and forty feet wide through solid basaltic rock ;
and the Colorado and Mississippi rivers, in each of which
cases the action which has been proceeding for centuries still

Fig. II.— Karrenfelder of the Alps, resulting from water-erosion. (After Heim.)

Fig. 12. — Water-erosion. The Yellow River, Shansi, China.

( To face paf;e 98.)

DISINTEGRATIOX THROUGH EXTERNAL FORCES. 99

continues to-day the work of surface modification, and conver-
sion of rock into soil.

The quantity of solid matter detached from its mass and
held in suspension or reduced to solution by the currents of
streams can be approximately rendered in figures, and reaches
an amount the aggregate of which is simply enormous.

Although the proportion of solid matter to water in streams
may seldom be greater than one to six thousand, yet even this
apparently slight amount reaches a quantity expressed by thou-
sands of tons as the annual burden of solid matter transported
by a single stream ; and in a period of six thousand years the
result is an amount equal to the annual weight of water flow-
ing in the river indicated.

The Mississippi detaches and carries to the ocean annually
3,702,758,400 cubic feet of solid material, a quantity sufficient
to cover an English square mile of surface 268 feet deep with
alluvium. The Ganges transports to the sea 6,368,000,000
cubic feet of sediment yearly. Yet these rivers are not re-
markable in their erosive effects, except through the magni-
tude of their currents.

Smaller rivers furnish facts of an identical nature. The
Thames is estimated to flow on the average 100,000 cubic feet
of water per day, bearing in suspension 1802 tons of mineral
matter, equivalent to an annual burden of 657,595 tons of
transported material.

Deposits made by Ruxxing Waters. The question next
naturally presented by the facts just considered is. What ulti-
mately becomes of this vast quantity of material removed from
the rocks and soils of water-sheds ?

The greater part of the suspended matter consists of fine
sand and silt gathered from all the soils with which the waters
come in contact, and of the finer particles of the rocks of the
reg-ion traversed. Mountain-streams and the head-waters of
most rivers, however, transport stones, ev^en boulders, not in-
frequently long distances.

Since all common rocks vary only between 2 and 3 in spe-
cific gravity, they lose nearly one half their weight when
suspended in river-water, the average specific gravity of which

lOO A'OCA'S AND SOILS.

varies from 1.005 to 1.500; and their transportation becomes
a matter requiring far less force than would be otherwise nec-
essary. Whirled and rolled onward by the current, the frag-
ments of broken rock become gradually transformed into
smooth, water-worn pebbles, and the abraded matter is added
to the fine sediment carried on by the stream.

The material thus gathered from .rock and soil is largely de-
posited along the courses of the stream, forming the alluvial
beds of their valleys, or becoming perennial accumulations of
fertilizing matter brought and laid on the meadows with un-
failing regularity with every succeeding overflow.

The distance of transportation may be either long or short,
according to the amount of sediment or the rapidity of cur-
rent ; the Nile and the Mississippi often bearing their gathered
burden thousands of miles, while in certain localities the trans-
portation may be only from one bank of the stream to the
other.*

Delta- FORMATION is the ultimate end of most of the vast
quantity of sediment not disposed of before the current gains
the sea. The material transported becomes thus deposited at
the mouths of the streams, forming regular strata of detached
matter, the coarser particles being laid down directly at the
river's mouth, the finer ones being carried farther out and
forming the outer portion of the islands rising from the
waters.

Deltas are often formed as the result of the emptying of
mountain-streams into lakes, where the calm waters of the lat-
ter compel the precipitation of the earthy matter brought to
them with the influx of rivers. But the chief delta-formation
results from the emptying of sediment-laden streams into the

* An aggravated case of this nature occurred in Hampshire County in Massa-
chusetts some years ago. The county is divided by the Connecticut River, the
towns of Hadley and Hatfield being thus separated; the elevation of the latter
above the river being several feet greater than that of the former. After one of
the annual spring freshets the current so changed as to abrade the high Hatfield
bank and transport the sediment thus obtained to the Hadley shore, where in time
an island of fertile alluvial soil grew, the ownership of which was decided after
litigation to be vested in the Hadley owners of the adjacent land.

ROCK-DISIiyTEGRATlON Til ROUGH EXTERXAL FORCES. lOI

ocean, the principal cause of their origin lying in the existence
of reefs or bars beyond the coast-line whereby lagoons are
formed, in the quiet waters of which delta-deposition is greatly
aided. The delta of the Nile furnishes a most perfect con-
firmation of this fact.

From the fact that delta-formation is not infrequently a
phenomenon of regions subject to gradual elevation of surface,
Credner* draws the inference that this elevation of surface is
the important factor in furthering delta-formation. He further
supports his conclusions by the fact that most great rivers free
from such formations, like the Hudson, Delaware, Amazon and
Elbe empty where the coast at present is undergoing gradual
depression of surface.

Glacier Action f is simply aggravated water action, for
glaciers are but streams frozen and moving slowly but irresisti-
bly onwards, down well-defined valleys, grind-
ing and pulverizing the rock-masses detached
by the force and weight of the onslaught. The
resulting amount of earthy matter transported
by streams having their origin in the waters
flowing from glaciers is not only enormous in
quantity, but possesses the peculiarity of con-
sisting of little but the finest rock-detritus free
from organic matter and earth alluvium.

Oceans may also not only be great sources
of erosive action, but may be the direct cause

Am.Dl.NuU C».

of land-formation from the transported mate- fig. 13. -Alluvial isi-
rial brought to the sea by the influx of rivers. ^"'^^' ""'^'^ °^ ^'°"''

. . Carolina, formed by

No better illustration of such formation exists opposition between

.1 ,1 rr J u ^1 J. ^ . c ocean and river action.

than those ottered by the coast structure of
North Carolina, where the sand reefs and islands inclose Pamlico
and Albemarle sounds; shallow stretches of brackish water into
which numerous rivers empty their waters laden with detritus,
which, meeting the tide, is flung up in reefs and islands, some-
times of sand, sometimes of mud, and then again building the
rich alluvial soils producing the renowned " sea-island cotton."

* Petermanns Geologische Mittheilungen, No. 56 (1878).
t See page 45.

102 ROCKS AND SOILS.

B. CHEMICAL ACTION OF WATER.

No water precipitated upon the Earth's surface from the
atmosphere, be it rain, hail or snow, is chemically pure hydro-
gen oxide. It invariably contains absorbed gaseous constitu-
ents of the air, chiefly carbonic-acid gas and oxygen ; the
former giving it a slightly acid reaction, the latter rendering it
a weak oxydizing agent ; while organic constituents absorbed
lend it reducing properties ; and the ammonia gathered and
conducted to the soil forms a most important fertilizing in-
gredient.

Though the amount of foreign substances thus existing in
the purest of waters is infinitely small, and to be detected only
by chemical means, yet to their presence is chiefly due the
chemical transformation wrought in the rock-masses of the
Earth. However, the quantity of these active ingredients is
immediately increased so soon as the water gains access to the
rock and soil, where decomposing animal and vegetable matter
constantly supply fresh accretions of each of these active in-
gredients of water.

Small as may be the total of these absorbed substances in
even the most impure of running waters, their action being
ceaseless and their supply exhaustless, the aggregate eventually
exerting itself against a given formation is, in reality, large ;
the lapse of time abundantly compensating for the minuteness
of the active agents and the slowness of the results accom-
plished.

To the chemist, minerals subjected to the action of water
which on filtration give no trace of soluble matter, either in re-
sponse to reagents or on evaporation, are held insoluble. But
to the geologist, such minerals may not only be considered
soluble, but even very soluble ; for he takes into consideration
not only the results of action continued through thousands of
years, but under constant repletion of the dissolving medium.

Geologically speaking there is no insoluble mineral, and all
rocks are, with greater or less rapidity, undergoing dissolution.
The dissolving power of pure water is least when exerted

DISINTEGRATIO\^ THROUGH EXTERNAL FORCES. IO3

against silicate of alumina ; but ev^en this is dissolved i part
for every 200,cxx) parts of water acting.

The disintegrating power of water may be exerted in either
of two distinct ways: first, by solution; and second, by combi-
nation. These two means, by which the results of water action
are accomplished, operate so commonly together, exerting their
united power against most rock-formations, that a practical
separation is useless.

The Penetration, Solution and Decomposition of rocks
by the action of water are universal ; no rock can escape, there-
fore, the water's action ; for where one property fails another
succeeds, and the combined action is resistless.

In the accomplishment of its ends, water is not compelled
to follow the crevices or strata of the rocks, for every rock-
mass consists of aggregations of minerals, and is permeated in
all directions by microscopic pores, through which the water
passes to the remotest recesses of the formation, extracting all
soluble material, and reducing the mass gradually to a softer
earthy material.

Even the natural silicates, the hardest and most insoluble of
rocks, are, to an appreciable extent, acted upon by chemically
pure water; and the hardest of flint-glass is dissolved slightly
by the action of boiling water.

Insolubility and freedom from decomposition are unrecog-
nized properties of rocks where the action of water is con-
cerned ; pseudomorphism (see p. 92) proving both the
solubility and decomposition of quartz, the most intractable
of all mineral forms ; while experiment shows that mere
pulverization reduces tourmaline, augite, hornblende and
other equally resisting minerals to forms readily soluble in
distilled water.

Solution by Water alone occurs to but comparatively
few rock-forms, and these are principally of simple composition ;
gypsum, rock-salt, limestone and dolomite forming the best
examples of rocks thus affected

Gypsum being among tme most abundant mineral forms, the
solubility of i part in 4or parts o! water becomes of great sig-
nificance in moulding the surface aspect of the Earth ; and as

I04 ROCKS AND SOILS.

lime forms an essential ingredient of all vegetation, this extreme
solubility is, from an agricultural standpoint, of inestimable
value, as it renders the mineral not only an abundant natural
source of plant-nutrition, but gives the substance great value
as an artificial fertilizer.

The extreme solubility of rock-salt is also of vast industrial
as well as geological importance, as to this property is due the
origin of all saline springs.

Limestone, though far less soluble in water than the two
preceding, is so extraordinarily abundant and wide-spread as a
geological formation, that its subjection to the dissolving action
of water is productive of the greatest change in the geological
structure of the Earth. It is soluble in water to the extent of
I part in looo parts, and much more soluble in carbonic-acid
acidulated water, to the action of which it is so universally
subjected. The distinction between the results as due to the
dissolving power of pure water or of acidulated wa'ter cannot be
drawn.

Nevertheless the dissolving of this rock and its removal by
running waters are productive of all-important changes in the
physical features of nature.

The caverns in which the earliest human remains are dis-
covered resulted from this removal of calcium carbonate, while
the enormous caves of Kentucky, Tennessee and Virginia are
of similar origin.*

Where the limestone is not of a homogeneous character, the
more readily soluble parts are washed away in the lapse of ages
to depths of 3 to even 50 feet, in deep narrow grooves or chan-
nels, separated by rugged ridges of less soluble rock, forming
the famous " Karrenfclder" of the Alps.

The conversion of Anhydrous into Hydrous minerals
by the addition of water results by direct combination, the
change in composition thus occurring chiefly affecting silicates
and metallic oxides ; orthoclase, albite, hornblende, augite, mica,
magnetic iron and hematite being typical illustrations.

The transformation is simply a chemical combination with

* N. S. Shaler in Scribner's Magazine, October 1887.

DISINTEGRATION THROUGH EXTERNAL FORCES. IO5

the elements of water, no other change in composition taking
place, time being the only essential for the reaction.

A wide-spread and important hydration of a mineral form is the
frequent change of iron oxide, hematite (red iron ore), Fe^Oj,
into iron oxyhydrate, limonite (brown iron-stone), Fe^HjO, :

2FeA+3H,0 = Fe,HA-

By an identical process, anhydrite (CaSOJ becomes, in time,
gypsum (CaSO^ -)- 2\\^0), a transformation quickly accom-
plished, and of very frequent occurrence in many geological
formations.

The Oxidation of minerals, resulting from the oxygen ab-
sorbed by waters, is a common change closely allied to the one
just noticed.

Aside from carbonic acid, water contains free oxygen ab.
sorbed or held in suspension, and all substances which unite
readily with this element undergo oxidation, therefore, when
brought into contact with such waters.

Most frequent among the transformations thus wrought are
the conversion of ferrous into ferric compounds ; spathic iron
(siderite), FeOCO,, becoming 2Fe203 -\- 3H5O, the carbonic acid
being displaced by water, and the protoxide by the attraction
of oxygen becoming sesquioxide. By a similar process mag-
netic iron (FeO -{- Fe^Oj) becomes hematite (Fe^Oj).

2Fe30, -f O = 3Fe,0,

This transformation has affected many extensive iron-ore
deposits, and accounts for the origin of important beds of iron
sesquioxide (hematite) in Brazil and the Lake Superior region.

Ores of manganese are subject to an identical proc-ess of
higher oxidation.

A series of transformations perhaps yet more important is
the oxidation of metallic sulphides into sulphates of the same
metals.

Iron pyrites (Fe S^^t thus becomes ferrous sulphate (FeSOJ,
which by further oxidation is transformed into brown iron-stone
or limonite (2Fe,03 -f- 3H,0) ; and the sulphuric acid set
free combines with other bases, as, for instance, it drives the

103 ROCKS AND SOILS.

CO, from limestone, and forms calcium sulphate or gypsum.
Zinc, lead, copper, cobalt and other sulphides undergo like
transformation with similar products of oxidation.

Thus through the action of water not only the physical
characteristics of rocks become changed, and physical results
are accomplished ; but the elements of water, or gases held
dissolved therein, combine chemically with rock-constituents,
changing the composition and character of the mass, and ren-
dering it susceptible to influences before inactive.

Rock-solution by the Carbonic Acid of Water. In
nature-, rooks are never exposed to the action of pure water,
and this power of solution is greatly aided by the CO, univer-
sally present in all spring and running waters. The oxygen
and certain salts so frequently held in solution also greatly add
to the solvent power, but in a degree far inferior to CO,.

The amount of CO, thus absorbed by water at ordinary
temperature and pressure reaches a bulk equal to that of the
water holding the gas, while either at lower temperatures or
greater pressures the volume of gas absorbed is largely in-
creased.

This acidulated water acts most forcibly on the carbonates of
lime and magnesia, and on the protoxides of iron and manga-
nese; compounds practically insoluble in pure water, but
found to a considerable extent in ordinary running waters.
Silicious minerals, too, so slightly affected by pure water, be-
come readily attacked and dissolved by carbonic-acid waters;
the insoluble silicates being converted into soluble carbonates;
lime, magnesia and iron being thus removed from the rocks,
and carried into solution.

The ordinary carbonate constituents of rock-formations, for
instance common limestone, are simple or mono-carbonates
which by the action of the CO, dissolved in water become
converted into bicarbonates, soluble in water, and held in solu-
tion. If, now, the solution be boiled, this additional CO, be-
comes disengaged, passes off, and the monocarbonate with
which it was combined is precipitated ; hence the efficacy of
boiling hard waters, rendering them fit for domestic use.

Decomposition of silicates, the most insoluble of rock-forms.

DISIXTEGRATION THROUGH EXTERNAL FORCES. lO/

by the action of the carbonic acid of v/aters, is of incalculable
importance, as the products are all comparatively soluble com-
pounds ; the recombinations resulting being, therefore, fraught
with ph\'sical changes of structure as well as with changes in
chemical composition of many rock-forms.

The bases from combination with which the silica is dis-
placed are most commonly potassa, soda, lime, iron and man-
ganese oxides. With these the carbonic acid combines to form
carbonates, while the silicic acid is set free.

The Earth's rock-mass consists largely of hornblende, feld-
spar and augite. These minerals are silicates of alumina or
magnesia combined with alkalis, with calcium, and with iron
and manganese.

These rocks are, therefore, decomposed by the carbonic acid
of the percolating waters, and carbonates take the place of sili-
cates in this most important series of rocks ; while the unde-
composed silicates of alumina and magnesia attract water,
and remain behind as hydrous silicates, minerals of which clay,
kaolin, chlorite, serpentine and talc serve as types, produced
by the transformation described.

Agriculturally considered, this dissolving power of carbonic
acidulated water is of vast importance, not only by reason of
the conversion of insoluble silicates into soluble compounds of
elements of plant-nutrition, but this solvent property is exerted
on a class of indispensable compounds, namely, the phosphates
of different bases. Especially phosphates of lime, magnesia and
iron, salts containing the essential ingredient of vegetation,
phosphoric acid, but existing in an insoluble and comparatively
worthless condition, are by the dissolving powers of the car-
bonic acid, however, rendered soluble and available as plant-
food.

III. Action of the Air.

As with water, so with air, the decom.position or weathering
of rocks through its influence is due chiefly to the presence and
activity of the two ingredients, carbonic acid and oxygen. The
action of the former as a constituent of the air, is mainly a

I08 ROCA'S AND SOILS.

repetition of its influence as an ingredient of water. Oxygen
produces its effects simply as an oxidizing agent, converting
protoxides into the higher oxides ; iron and manganese miner-
als being most frequently thus affected ; and these minerals
enter into the composition of a very large number of the more
prevalent rock-formations: mica, amphibolc, chlorite, talc, ser-
pentine and feldspar being good instances of the occurrence of
the protoxides of iron or manganese, convertible into higher
oxides by the action of atmospheric oxygen.

Iron sulphide, so abundant in many rock-forms, is also af-
fected by the presence of oxygen, the iron being converted into
the sesquioxide ; the sulphur combining with oxygen and
water to form sulphuric acid, 2FeS2 + 9O = Fe^Oj -)- 2SO3 ;
SO3 -}- H,0 = H,SO,. Rock -disintegration is materially
hastened by this decomposition or oxidation, particularly as
the higher oxides occupy more space than the metals or the
lower oxides ; thus the result is due to both chemical and physi-
cal changes.

The sulphate of the protoxide of iron, FeSO,, illustrates the
fact, by the oxidation of the clear green crystal of the pro-
tosulphate FeS0,+7H,0 to the more bulky, brown, opaque
sulphate of the sesquioxide; a bottle filled with the former
being made to overflow by the formation of the latter through
attraction of oxygen.

These products are soluble in water, and enter readily into
solution in spring and running waters ; and by their presence
still further chemical decomposition and combination result.
Carbonate of lime becomes gypsum ; dolomite becomes bitter
salt, Epsom salts or magnesium sulphate and gypsum ; sodium
chloride, or rock-salt, is transformed into sodium sulphate, or
Glauber's salt ; and most important of all, the insoluble tribasic
calcic phosphate, Cd^^iVO^, becomes soluble monobasic cal-
cium phosphate, CaH^PO,),, and gypsum l^2CaS0,).

This soluble calcium phosphate is the "superphosphate" of
commerce, the most valuable form of agricultural phosphoric
acid; and the reaction thus occurring in nature is identical with
that performed in the fertilizer manufacture by treatment of
bones or rock-phosphates with sulphuric acid.

DISINTEGRATIOiY THROUGH LXTl-lKXAL FORCES. lOQ

Modifying Influences affecting Rock-solution.
Aside from these chief causes of rock-decomposition, others
of more or less significance as modifiers, or as producers, of
rock-decomposition, exert themselves under varying circum-
stances. Every solution of a salt, indeed the solution of every
material occurring naturally in the moving waters of soils, be
the solutions of natural occurrence or the result of artificial
fertilization, exerts itself on the insoluble soil silicates decom-
posing them, and forming therefrom soluble salts of bases which
are essential ingredients of plant-food. This action is particu-
larly noticeable in the case of salts of ammonia, lime, potash
and soda, many of the compounds of which are among the
most important sources of vegetable nutrition.

The form of the chemical combination, the degree of hard-
ness, and the character of the individual rock-ingredients or
mineral constituents, determine the degree to which the de-
composition is effected by the factors of disintegration.

The mechanical nature of the rock attacked is likewise of no
inconsiderable importance in determining the result ; the fine-
grained, compact basalt, for instance, being far less readily de-
composed than the coarse-grained, more or less porous granite.
Even a given rock may resist the disintegrating influences
differently in its different constituents. Thus the feldspar of
granite is often reduced to a fine white clay, while the mica
and quartz exist as fine undecomposed particles, intact and
unaffected by conditions destroying the more easily-disinte-
grated feldspar.

IV. Action of Organic Life.*

The modifying or transforming influences exerted on rocks by
living organisms are not of an occasional or isolated nature, but
are of almost universal occurrence, pursuing their ceaseless action
as quietly and nearly as resistlessly as the ever-acting water.

* In this connection only the action of life as a promoter of rock-disintegration
win be considered ; the incorporation of animal and vegetable matter with the de-
composed materials of rocks, and the modifications in soil composition and charac-
teristics resulting from the action of life, are considered in Part Third.

no A'OCATS A.VZJ SOJLS. '

The variety of action exerted by animal and vegetable life i?
very great, but the means by which the results are accom-
plished are either physical or chemical, or a combination of
the two.

Animals exert their disintegrating tower always
through chemical means, the result being actual chemical de-
composition through the exertion of chemical affinity. Yet
the geological activity of animal life is more distinctively
formative than destructive ; coral reefs, chalk and flint deposits,
and the infusorial earth composed of diatomes so small as to
contain 41,000 millions of distinct organisms to the square inch,
being wholly of animal origin, while by far the largest portion
of all limestone formations are composed chiefly of aggrega-
tions of calcareous lower organisms.

Reduction through organic decomposition is a most
frequent and important effect of animal or vegetable existence,
since the death of these organisms furnishes through the pro-
ducts of their decay the hydro-carbons which are the chief
natural reducing agents of mineral forms.

These products of organic decomposition act not only at the
surface, but, passing into solution in the percolating waters, they
penetrate the deepest depths of geological formations, exerting
their reducing influences through all the regions penetrated.

By these means carbonic acid is evolved through the extrac-
tion of oxygen from higher oxides which become thereby
reduced to lower oxides, with which the carbonic acid evolved
combines to form carbonates of monoxides. These b}- the
action of the atmosphere are transformed into hydrous oxides,
and thus precipitated, iron being most frequently thus affected.

In similar manner, sulphates through loss of oxygen become
sulphides through the action of decomposing organisms ; and
the sulphides may, by a continuation of the process, lose their
sulphur by combination with oxygen, and metallic copper,
zinc or lead may be the result, according to the base originally
combined with the sulphuric acid reduced.

The presence of pyrites as the fossilizing material in numer-
ous fossilized ammonites, brachiopods and gasteropods is thus
explained through the reducing action of the decomposing

DISIXTEGRATION THROUGH EXTERNAL FORCES. HI

animal on the mineral sulphates with which it Mas surrounded.*
Sulphates of the metals are not alone thus affected ; but also
the compounds of sulphuric acid with the alkalies and alkaline
earths, by the reduction of which hydrogen sulphide is evolved
which, in turn, may combine with metals and form sulphides,
or may by atmospheric oxidation result in the deposition of
free sulphur.

Plants accomplish their decomposing effects per-
haps fully as often through physical as through chemical
means. Aside from the incorporation of organic matter with
the mineral matter of the soil by extraction or absorption from
the air through the vegetable organs, and conveyance to the
soil through death and decomposition thereon, the organs of
plants act directly as rock-disintegrators, both chemical and
physical action being exerted. In both cases the roots are
the chief factors by which the result is directly accomplished.

The Chemical Action of the Root as a rock-disintegra-
tor is accomplished by means of the secretion and excretion,
through the pores of the root, of an organic acid which pos-
sesses the property of decomposing and dissolving the rock-
mass with which it comes in contact, f rendering it plant-food
and directly assimilable ; thus filling an office to the plant
closely allied to that of the gastric juice in the animal organism.

The Physical Action of the Root is in as great a de-
gree allied to the action of frost as a rock-disintegrator. The
roots permeate the rock-mass wherever the slightest crevice of-
fers an entrance ; and then, by the expansive force of the grow-
ing tissue, the most tenacious of rocks are rent and torn asun-

* An exceedingly interesting phenomenon of this nature is known to have oc-
curred in Tennessee during the American civil war. A copper mine near the
village of Ducktown was closed because of the hostilities. The exposed ore of
copper sulphide became converted by oxidation into copper sulphate, which became
dissolved by the percolating waters gathered at the lower levels of the mine.
When work was begun again after the close of the war it was found that where-
ever the timber supports of the galleries stood in the copper-sulphate-impregnated
waters, reduction of the sulphate had resulted from the decomposing wood; and
deposits of metallic copper adhered to the immersed pillars. Credner records
similar occurrences in mines in Ireland, Spain and Germany.

f Meyer, Lehrlmch der Agricultunhemie (Heidelberg, 1S76), p. 364; Pfeffer,
FJlanzenp/iysiologie (Le'x^zi^, 1S81), Bd. I. pp. yS-So.

112 ROCK'S AND SOILS.

der, no power in nature being able to withstand the force of
this slow-working but resistless expansive action.

The disintegrating power of different rcots on various rock-
formations was experimentally demonstrated by Dietrich with
the following results :

, Mineral Matter Dissolved. >

Varietv op Plant. ^anegated 3,^,,

Lupine 0.60S0 grtn. 0.7492 grm.

Peas 0.4807 " 0.7132 "

Buckwheat 0.2322 " 0.3274 "

Vetch 0.2212 " 0.2514 "

Wheat 0.0272 " 0.1958 "

Rye 0.0137 " 0.1316 "

From the above figures it appears that during the period of
growth either the pea or the lupine will disintegrate more rock
than will the weathering process during the same interval.
The definite comparison is as follows :

, Mineral Matter Dissolved. ^

K Ca Mg P5O5

Weathering process 0.03SS 0.4516 0.0S92 0.0356

Peas 0.0684 0.521S 0.1230 0.0S68

Lupine 0.0920 0.4625 0.1332 0.0971

All roots and most other growing vegetable tissues possess a

distinctly acid reaction,* and the presence of minute quantities

of these vegetable acids in water renders

**^."*i|(*~-^ ^.l! ^fc-i'K ^^^ latter capable of reducing to solution

i^^?^ f^B<^h^W^% salts not soluble, and therefore unnutri-

2^-^°-/-/iA ■ -I : tive substances, in pure water.

j^^l^^^f^y^v^-f'-^iii^ Aside from this action of the living

■■•'■• '' plant on rock-dismtegration on sou

Fig. 14. - Illustrating gradual formation aud Utilization, the death and

transformation of bed-rock (3)

into subsoil (2) and cultivated dccompositiou of tlic plant is a most
soiid). (After Geikie.) potent factor in the transformation

of mere disintegrated mineral matter into soil capable of
sustaining vegetation. The roots of all plants die either
wholly or in part each year, and by decomposition become, in
longer or shorter time, incorporated with the soil, giving it
back not only the material originally taken from it, but also
the 95/?, or more, of organic matter of atmospheric origin.
And where not reassimilated by subsequent vegetation, as, for

* Liebig, Die Chemie in Hirer Anwendung auf Agricultur und Physiologic
(1862), vol. i. p. 137. " Die Wurzeln scheiden hiernach eine Saure aus."

DISINTEGRATION THROUGH EXTERNAL FORCES. II3

instance, in forests or under water, the mass of vegetable mat-
ter, roots, leaves, whole plants, results in time in the accumula-
tion of vast stores of decomposed or decomposing vegetation :
leaf-mould, muck, humus ; material recognized as forming a dis-
tinct geological formation of the Diluvial epoch.

The transformation of the living plant-tissue into these pro-
ducts of decomposition is due to distinctly chemical causes
resulting in chemical action. Decomposition is fundamentally
oxidation ; and here the decaying mass consists chiefly of car-
bon and hydrogen, which become by union with atmospheric
oxygen oxidized into carbonic-acid gas (CO,) and water, with
marsh-gas (CHJ and carbon monoxide ; while the albuminoids,
nitrogenous constituents of vegetation become transformed
into ammonia (NH3) and nitric acid (HNO3). Further than
this, the decomposition of vegetable matter results in the for-
mation of geic, ulmic and humic acids ; while the first by further
oxidation gives rise to the stronger crenic and apocrenic acids.

The effects of the action of the products of this organic
matter on the mineral ingredients of the soil are manifold.

1. By their hygroscopic properties they keep the soil in a
moist condition,

2. Their decomposition is a fruitful source of carbonic-acid
gas (CO J, the results of the action of which have already been
noticed.

3. The acids produced act as direct disintegrators of rocks
and the mineral constituents of soils, reducing insoluble matter
to soluble plant-food.

4. The nitric acid formed results by combination in nitrates,
the most valuable form of nutritive nitrogen, while the am-
monia and other salts formed are direct plant-food.

That humus itself can be assimilated, or is required by the
plant, is wholly disproved. It simply yields material utilized
by the plant, in lieu of other source, and acts as a producer of
plant-food by action on insoluble ingredients of the soil.

This combination of organic and inorganic matter completes
the formation of soil from disintegrated minerals.^

* For further consideration of these products of organic decomposition, see
Part Third.

114

ROCKS AND SOILS.

CHAPTER IV.
PRODUCTS OF ROCK-DISINTEGRATION.

Weathering is the term applied to the combined action of
the elements, or of all atmospheric action exerted against rock-
forms.

The time required for the weathering, or disintegration,
of various rocks has formed the subject of extensive experiment,
the most reliable results of which demonstrate that the disin-
tegration of Jurassic limestone to the depth of i metre would
occur at the end of 72,800 years of atmospheric action ; while
the same depth of syenite would be similarly affected after a
lapse of 731,400 years.

The exact results of rock-disintegration are most forcibly
presented by Wolff's analyses of the progressive products ob-
tained from two different rock-forms.

I. Composition of the producis of the weathering of VARIE-
GATED Sandstone.

Water and organic matter.

Silicic acid, SiO^

A1,0,

FeO

MnO

CaCO,

CaO

MgO

H,S04

P»05

K,0

Na,0

Fine-grained
Undecom-
posed Sand-
stone.

per cent.
0.6236
91-7348
3-7425
I. 4891
0.0167
0.0854
0.0949
o. 1114
0.0095

0.0249

1.8925

0.0825

99.9078

Rock of the
Sub-soil.

per cent.
2.6190
81.8343
7.6152
3 -7450
0.5078
0.0988
0.0876
0-2555
0.0093
0.0457
2.7847
0.4420

100.0569

Fine Earth

of the

Sub-soil.

per cent.
4.6637

78.8766
9.6989
30253
0.1450
o. 1050

0.0745

0.I6I6
0.0080
0.0498

2.6499
0.3728

Arable Soil.

per cent.
10.9642
73 0505
9. 1640
2.5463
0.2083
0.2300
0.1158
0.2167
0.0304
o . 0940

2.7214
0.3859

99.8311 I 99.7275

PRODUCTS OF KOCK-DISINTEGRATIOy.

II

II. Composition of the products of the weathering of SlLI-
cious Limestone.

Water, and loss by ignition

SiOj, insoluble

SiOi, soluble

AljOs. insoluble ,

AUO3, soluble

FeaOs

FeCO,

MnO

CaCOa

MgCO,

CaO

MgO

P2O5

H,S04

K,0

Na^O

Unweathered
but Crumb-
ling Lime-
stone.

per cent.
I. 2010

15.0913
I 0439
o. 1301
0.6199
0.0920
2.8463
0.3633

77.1607

I -0437
0.0134
0.0148
0.1963
0.0166
0.1487
0.0632

100.0452

Loose parti-
cles of

Crumbling
Rock.

per cent.
3.65S0

40.1820
I .6629
0.1026
I . 1633
8.7048

0.6017
43.1071
0.7210
0.0255
0.0371
0-5304
0.0475
o. 1641
0.0579

100.7660

Sub-soil.

per cent.

7.6970
54-5304
11-2359

O.S073

7-2517
9-3935

0.7600
6.2362

0.3717
0.1027
0.3884
0.4833
0.0493
1 .2151
o . 2408

100.7633

Cultivated
Soil.

per cent.

8.9362

55-4569

11-7193
I. 07 10

7 9043
8.1769

0.6600
2.6400
0.3927

0-1515
0.3740
0.4650
0.0583
1-5473
0.3429

99.8963

The relative weathering susceptibihty of different rocks has
been experimentally demonstrated. One-half cubic foot of
variegated sandstone, of shell limestone, of basalt, and of Roth,*
were subjected to atmospheric influences for four years, under
like conditions. The amount of disintegration was determined
by passing successively through sieves of graduated fineness.
The results were classed in three divisions, as fine earth, sand
and rock physically unchanged, with the following percentage
results:

Variegated Shell d,„„i. d«.k

Sandstone. Limestone. ^^^"- ^°'*»-

1. Fine Earth 2.61 1.38 0.47 3.12

2. Sand 4.32 4.87 2.52 49-44

3. Unchanged 93.07 93.75 97.01 47-44

From these investigations it appears, as was to be expected.
that Roth, typical of the shales, is of all common rocks most

* A variety of argillaceous shale, usually existing in conjunction with variegated
sandstone, and a distinctively German variety.

Il6 ROCKS AND SOILS.

easily attacked by the weathering influences, and most rapidly
converted into soil ; while basalt remains the most obdurate.

For a more definite understanding of the actual results of
rock-disintegration a consideration of the products of the weath-
ering of each individual rock-form becomes necessary.

I. Products of the Weathering of Simple Crystal-
line Rocks.

Quartz is wholly unaffected by the weathering process, ex-
cept by the action of freezing water whereby it becomes sepa-
rated cr>'stal from crystal. The particles thus formed may be
ground to fine sand by the action of running waters, but the
product of such action remains quartz, and quartz only, though
it may be mixed with the products of the destruction of other
rock-forms.

Feldspar may be transformed into various products of de-
composition according to variety and composition. With the
lapse of time the potash, soda, lime and a part of the silicic
acid become disolved by the action of carbonic-acid-saturated
waters, and, finally, silicate of alumina (clay) and carbonate of
lime or their mixture remain behind, together with traces of
the silicates of soda and of potash, forming either kaolin,
clay or inarL

Oligoclase weathers most readily among feldspars because
of its content of lime, while ortlioclasc decomposes with far
greater difficulty, its decomposibility being inversely propor-
tional to its content of soda and iron protoxide.

Zeolite decomposes with great ease because of the presence
of considerable quantities of the alkalies and alkaline earths.
This fact is of considerable importance because of its bearing
on the transformation of rocks containing zeolite, basalt for
instance, into agricultural soils, because of the destructibility
of the zeolite.

Hornblende weathers easily or not, according to presence
or absence of considerable quantities of lime and iron prot-
oxide. Because of the comparative absence of aluminium
oxide, its silicate, or clay, is not a product of hornblende or '

PRODUCTS OF ROCK-DISINTEGRATION. 11/

augite decomposition, but compounds of iron, carbonates of
lime and magnesia and the silicate of the latter.

Mica is among the more indestructible rocks and possesses
the peculiarity of decomposing from the interior outwards.
The rapidity of the process depends on the quantity of sodium
oxide present, the process being furthered by the presence or
increase of soda. As a result the potash and magnesia micas
remain intact long after the soda variety has become wholly
decomposed. The presence of iron protoxide also increases
the facility with which mica weathers.

Potash mica yields yellow clay (ochre-colored from the pres-
ence of iron) mixed with glistening particles of undecomposed
mica. In the case of magnesia mica this product is mixed with
the carbonates of magnesia and of lime.

Talc and Serpentine seem to be wholly unaffected by
atmospheric agencies. Wherever these rocks come to the sur-
face, soil is wholly wanting, and no vegetation finds a habitat.

Calcite not only becomes decomposed by weathering into
calcareous sand, but is also attacked by carbonic acid present
in water, and dissolved by the same and taken into solution.

Dolomite weathers with greatest difficulty, even when con-
taining iron protoxide, and without this ingredient only the
action of frost is able to reduce dolomite rocks, which become
thus transformed into sand closely resembling quartz-sand in
properties, and nearly as insoluble, though finally reduced to
solution by carbonic-acid-aciduiated waters.

GypsUxM is extremely soluble in the moving waters of the
soil ; a fact of inestimable importance agriculturally, as it be-
comes incorporated with the soil as a constituent part, thus
readily furnishing the plant with the essential calcium.

Magnesite is readily weathered, becoming an asbestos-like
compound capable of becoming a pseudomorph of talc*

Olivine changes rapidly under atmospheric action. The
first change results in the appearance of a dirty green color,
which finally becomes brown through oxidation of the iron-
protoxide. The final products of the decomposition are very

Roth, C/iemische Geologic, Bd. I. p. 182.

Il8 ROCKS AND SOILS.

numerous. Silica may be displaced by carbonic acid, or mag^
nesian and iron silicates may be replaced by water, serpentine
being the result.

Leucite decomposes by the weathering influences into a
kaolin-like product ; the transformation is, however, slow and
but partial.

Nephelixe becomes under atmospheric influences trans-
formed into zeolith.

Iron minerals as affected by the weathering influences
have been considered under the action of air and of water as
decomposers of rock-forms.

II. Products of the Weathering of Compound Crys-
talline Rocks.

Granite decomposes into its constituent minerals, feldspar,
quartz and mica, accompanied by a more or less important
production of clay.

Syenyte becomes by the weathering agencies transformed
into clay, usually yellowish in color, and impregnated with bits
of hornblende and chlorite undecomposed.

Gneiss forms on weathering a yellow-tinted clay-like prod-
uct, with particles of mica and feldspar.

Granulyte decomposes with greater difificulty than either
granite or gneiss, being not infrequently, however, converted
into a nearly pure kaolin mixed with intact crystals of quartz.

Porphyry results through weathering in a considerable
number of products, varying with the composition of the
original rock. The product is, however, of a clay character,
but may, if originating in a porphyry rich in potassium-oligo-
clase, contain from 2 to 6 per cent of calcium carbonate.

Trachyte becomes transformed into an impure kaolin, ap-
proaching nearer genuine kaolin in character with the increase
in the amount of feldspar entering into its composition,

Phonolyte results in the formation of a marly product,
whitish in color, very insoluble in water, and haidening from
its solution or water-deposition into a very compact and hard
mass. In localities, therefore, where subjected to drying or

PRODUCTS OF ROOK-DISINTEGRATION. I ig^

sun-hardening it forms a most unmanageable and sterile soil ;
where retaining a constant and considerable amount of water,
on the contrary, it forms a fruitful soil, containing 2-5 per cent
of calcium carbonate and 5-10 per cent of sodium com-
pounds.*

MiCA-SCHlST varies in the products of its decomposition,
according as the mica entering into its composition be of the
potash or of the magnesia variety. Quartz-sand is an ac-
companiment of the weathering, together with iron oxide and
particles of chlorite and talc bedded undecomposed in the loam
formed.

Slate weathers to clay, impregnated with particles of mica,
quartz, chlorite and hornblende.

DiORITE forms many and varied decomposition-products.
Hornblende diorite, containing little lime but much magnesia,
with oligoclase weathers with difficulty, producing, however, a
fertile loam free from quartz-grains. Lime-diorite, containing
hornblende and feldspar, decomposes faster, producing a
clayey product, yellow-colored from the iron of the hornblende,
containing 5-10 per cent of lime and considerable quantities of
carbonate of magnesia.

Basalt weathers with greatest difficulty for the formation of
a marly product, containing large quantities of iron oxide, im-
parting a brownish or greenish color, together with particles of
chlorite and of augite.

Diabase weathers with products more or less resembling
diorite, augite or chlorite, as one or the other of these minerals*
predominates.

Melaphyre becomes after ages of weathering a red-brown
clay, when dry an impalpable powder, when moist a most tena-
cious soil containing, however, 10 per cent or even more of cal-
cium carbonate.

Hyperyte is transformed into loam containing large quanti-
ties of calcium carbonate, even 5 per cent, but only traces of
either soda or potassa.

Granular limestone is readily transformed into calcium

* Gohren, Ackerbauckemie, Bd. I. p. 27.

I20 ROCKS AND SOILS.

bicarbonate, thus passing into solution. The rapidity of the
change is modified by the presence of magnesian carbonate, so
prevalent an accompaniment of crystalline limestones.

III. Products of the Weathering of Non-crystalline

Rocks.

All fragmental or sedimentary rocks, without doubt, once
existed in the form of soil resulting from the weathering of
crystalline rocks, precisely after the manner of transformation
occurring at present. During this former existence they were
surely the habitat of plants securing their sustenance from
them.

These rocks are, therefore, not only transformable into such
soils again, but all the soils of to-day, sand, clay or loam, are as
certainly capable of re-formation into rocks, sandstone, slate, by
subjection to the proper solidifying and metamorphic influ-
ences.

The entire series of non-crystalline rocks are liable to trans-
formation into soils by the decomposing influences of water
and frost, but the properties and composition of the products
vary materially with the nature of the binding material of the
rock acted on.

Clay, the most frequently occurring binding material, be-
comes, by the constant action of water, a clay-like mass con-
taining particles of sand and undccomposed material, the fer-
tility of the resulting soil depending on the composition of
these more insoluble and enduring substances, without the
presence of which the resulting soil can be little but the silicate
of alumina with iron oxide and sand, or possibly some silicate
of magnesia.

Grit, consisting as it does chiefly of silicic acid, disintegrates
with great difficulty, and forms finally a sandy soil somewhat
more fertile than that resulting from quartz disintegration, be-
cause of the small amounts of iron-magnesia and of organic
matter present.

Tufa is a term describing more particularly the manner of
origin of a class of rocks than either the chemical or physi-

PRODUCTS OF ROCK-DISINTEGRATION. 121

cal characteristics of the product. One fact, however, holds
true of all varieties of tufa; they are all of volcanic origin, and
therefore all possess properties similar to those of crystalline
rocks ot igneous origin resulting in products of disintegration
similar to those of basalt, trachyte and phonolite ; with the differ-
ence, however, of more rapid decomposition and a larger yield
of fine earth, with increased content of carbonates and sodium
salts.

The predominating constituent is, however, silica, lending
an invariable sandy texture to the product. There are tufa-
formations possessing a composition more nearly allied to that
of wood-ash, containing considerable quantities of potash and
of phosphoric acid, the decomposition of which results in the
formation of soils of almost exhaustless fertility; illustrated by
certain localities in Italy and the Black Sea region of Russia.

Other soils of tufa origin are so abounding in silica as to not
only furnish little vegetable nutriment, but as to be almost
unworkable with steel or iron implements because of the scour-
ing to which they are subjected. Yet even these are finally
capable of yielding a product of fertile productive soil.*

S.\ND AND GRAVEL are transformed by the weathering agen-
cies only very slowly, producing widely-varying products with,
however, silica as the ever-predominating constituent.

Sandstone, consisting chiefly of quartz particles held to-
gether by a more or less tenacious binding material, is very
easily disintegrated. This binding material, being in general
exceedingly soluble, is more frequently washed away, leaving
only the pure sand behind. When this does not take place,
however, but the sand remains mixed with a considerable
quantity of both mineral and organic matter* the soil resulting
is usually one of considerable fertility, and particularly adapted
to certain uses because of the warmth resulting from the ab-
sorptive powers of quartz towards the sun's rays.

Because of the solubility of the unsilicious portion of the

* Large areas in Yesso naturally fertile and covered with forests of maple and
magnolia are of tufa origin, and unworkable and untillable because of the gritty
nature of the soil, in which a steel plough will not endure twenty-four hours ot
steady use.

122 ROCKS AND SOILS.

sandstone, the product of the disintegration of new sandstone
is far less fertile than that resulting from the decomposition of
sandstone of earlier date ; as the latter has not passed through
a second or third process of weathering, solution and re-solidi-
fication, but exists as the original sedimentary deposit of the
disintegrated material of early crystalline rocks.

Greensand, though decomposing with difificulty, consists
largely of the silicates of potash and of iron, soluble under the
influence of carbonic-acid waters, and therefore yielding ele-
ments of fertility with comparative ease, phosphoric acid in the
form of calcium phosphate from organic remains adding value
to the product.

Shales disintegrate with ease both under the action of
water and of air; the product is clay of varying composition,
but not infrequently containing considerable quantities of so-
dium, potassium, calcium and iron compounds.

Chalk undergoes little chemical change as the result of
weathering, the change being chiefly of a physical nature
whereby combination with organic matter is facilitated.

Marl, most closely resembling chalk in characteristics, is
similarly affected by weathering influences. The product is,
however, superior because of the presence of magnesia and of
phosphate of lime from organic sources.

Having now reviewed and recorded the definite results of
atmospheric action as applied to each individual variety of rock,
we are prepared to intelligently and advantageously consider
the ultimate products of this action — the combinations of these
various disintegrated rocks when united with organic mat-
ter, and thus transformed into soil. The fact must, meanwhile,
not be lost sight of that every soil thus formed must of neces-
sity partake of the composition of the rock in whose disintegra-
tion it had ori'jin.

PART THIRD.

CHAPTER I.
ORIGIN AND COMPOSITION OF SOILS.

The disintegrated rock whose progress toward soil-formation
we have thus far followed undergoes one further transformation
before the final product capable of sustaining vegetable exist-
ence appears. Plants consist of both organic and inorganic
matter, and, though the chief part of the former is of atmos-
pheric origin. It must, to a certain extent, be obtained from
the soil ; therefore only with the presence of both classes of
matter does the disintegrated rock arrive at the true condition
of soil. This necessary incorporation of organic matter with
the mineral constituents of rock origin results chiefly through
the action of living organism, either animal or vegetable.*
Nitrogen, however, so important a constituent of all living
organism, becomes a soil-constituent largely by absorption from
the atmosphere in the form of ammonia.

The action of plants and of animals toward soil-formation
are, however, so essentially different that a separate considera-
tion of each is rendered necessary.

I. Plants as a Source of the Organic Constituents

OF Soils.

Geological evidence all tends to establish the early existence
of vegetable forms on the Earth ; only the earliest Archaic
rocks are known to have been formed previous to the appear-
ance of the lowest forms of plant-life. The method employed
by nature for the incorporation of vegetable organic matter
with the inorganic mass of the Earth-crust, or the development

* In this connection it should be borne in mind that, chemically considered, only
that material is organic which contains the element carbon.

124 HOCKS AND SOILS.

of organisms on a purely mineral soil, needs no hypothetical ex-
planation, but is to-day practically illustrated by the transfor-
mation of solidified lava from recent volcanic eruption into a
plant-supporting soil.

The eruptive mass, like the original Earth-crust, appears as a
molten, glowing aggregation of different kinds of wholly inor-
ganic matter. It cools by the radiation of heat and becomes
igneous rock. Through time's metamorphosis it begins to dis-
integrate ; and presently the simplest forms of microscopic
vegetable life appear, finding the simple requirements of their
existence on their rocky habitat, and, procuring organic matter
from the atmosphere, finally die. The substance of their
organisms becomes deposited on the rock-surface to which the
lowly plant adhered.

Each generation of life adds to the accumulated organic mat-
ter thus covering the rock-mass. The process continues; the
weathering influences play their part ; and the deposited organic
matter becomes mingled with the disintegrated mineral matter,
a true soil, however minute may be the quantity, being the
result. Gradually but ceaselessly the depth of soil increases
as the action continues, and the character and nature of the
vegetation advance apace, the plants themselves adding to the
disintegrating forces engaged, till finally with the lapse of
years the original rock-formation becomes completely buried
beneath the accumulation of mineral and organic matter incor-
porated together; a perfect agricultural soil capable of support-
ing the highest organisms of the vegetable world is finally
formed.

The rapidity of the increase in organic matter through the
life-function of the plants finding a habitat on different soils is
shown when we remember that of the entire weight of all
plants not more than 5^ in any case is of soil, or mineral,
origin ; the remainimg 95^ is wholly of atmospheric origin ;
most of which becomes added to the soil-mass on the death and
decomposition of the plants.

The amount of organic matter thus becoming incorporated
with the soil is not ordinarily a large proportion of the entire
soil-mass, though the limits of variation are great. Though

ORIGIN AND COMPOSITION OF SOILS. 1 25

the quantity of organic matter absolutely necessary as a con-
stituent of soils for the production of plants is very small, the
amount which may be present in soils consisting chiefly of de-
composed vegetation is proportionally large. Peat may contain
as high as 70^ of organic matter in its dry mass, while some
prairie and long-enriched garden soils not infrequently contain
25^ under like conditions. The rich alluvial of the Mississippi
Valley seldom contains more than 10^ of organic matter, and
few agricultural soils contain over \^%, while the average for
good productive lands is not above 6^, clays seeming to
contain the highest average amount among arable soils, pre-
senting not seldom even \2%. Most common crops are, how-
ever, produced from soils containing far less than this propor-
tion. Oats, rye and buckwheat thrive with the lowest amount
of organic matter, requiring but from i to 2 per cent, while
wheat and tobacco evidently require most among common agri-
cultural products growing best in those soils containing from 5
to 8 percent of dry organic matter. The process by which this
organic matter becomes incorporated with the soil is simply the
decay of the organism furnishing it. The organic constituents
of the soil are, therefore, all products of decomposition; the
character of which is important as bearing on the nature of the
transformation wrought in the composition of the inorganic rock-
mass by this accession.

The entire product of the decomposition process is collec-
tively designated Humus; a term not defining a definite
product, but embracing all the non-volatile solid products of a
definite chemical action or decomposition. But decay or
organic decomposition is a process identical with combustion ;
the products are ever the same, and the ultimate end is the
formation of water and carbonic acid, with a residue of mineral
matter or ash, if such existed in the burning or decaying body.
Humus, therefore, is not the end of a process, but an interme-
diate stage of the transformation. Hence, were no addition of
fresh humus from newly-decomposed organic matter con-
stantly made, the soil must become devoid of this material
through its gradual transformation, or the final completion of
the process of decomposition.

126 ROCKS AND SOILS.

Under ordinary conditions of decay, however, the accession
of fresh material is more rapid than the loss occasioned through
the ultimate completion of the combustion. It thus appears
that the result of the decay of vegetation is not only the addi-
tion of organic matter, or humus, to the soil, but that there is at
the same tivie a constant accession of mineral matter from the
same source. And, moreover, that only by constant replenish-
ing of the supply of the material undergoing decay, and the
gradual passing of the material through the various stages of
decomposition, is the organic content of the soil perpetuated.

The Conditions Essential to Organic Decomposi-
tion are those most favorable to combustion or oxidation —
access of air, presence of moisture and application of heat.

The air combines with the constituents of the decomposing
body to form products of oxidation ; and the diminishing of
the supply of air immediately checks the rapidity or complete-
ness of the decomposition, thus explaining the accumulation of
peat under water, and of leaf-mould under the protecting
upper strata of deposited material. The presence of moisture
and of warmth aids the humus-forming process, inasmuch as
all chemical action is increased or rendered more energetic by
the action of one or both of these agencies.

Besides these abettors of decay, the chemical activity exerted
may be increased by the action of any caustic alkali or alkaline
carbonates. The latter by neutralization of acid products, the
former by direct decomposition.

Should the decomposing organism contain albuminoid
material, protein compounds, as is almost invariably the case,
the decay assumes a different form, known as putrefaction, re-
sulting from a process of fermentation the products of which
are, in addition to those otherwise arising (water and carbonic
acid), compounds of hydrogen with carbon, nitrogen, phos-
phorus or sulphur.

The carbonic acid formed through organic decomposition is
of incalculable agricultural significance, since it not only exerts
a most important influence on the mineral constituents of soils,
as already noticed, but supplies plants with the carbon forming
so large a part of their organic material.

ORIGIN AND COMPOSITION OF SOILS. 12/

But organic putrefaction results in the evolution of another
gaseous compound of only less importance ; namely, volatile
ammonia-gas resulting from the union of nitrogen and hydro-
gen (NHJ. This gas combines most readily with acids for the
formation of ammonium salts, among which the carbonate
((NH,)„C03) only is volatile and escapes to the atmosphere.

In the soil, however, only a comparatively small amount of
the total product of ammonia is volatilized, both because of its
combination with acids and its absorption by humus.

The ammonia thus resulting from putrid fermentation un-
dergoes a further decomposition known as nitrification, result-
ing like the original putrefaction from the action of oxidizing
microbes through the activity of which ammonia becomes
transformed into nitric acid.*

The transformation is doubly important inasmuch as loss
from volatilization is prevented; and moreover the new form in
w^hich the nitrogen exists is one furnishing this essential element
of plant-nutrition in a form far more assimilable and readily
available by the crop than in the previous or ammonia condi-
tion.

The most recent experiments at Rothamstead with reference
to the relative value of nitrogen as plant-food in the two forms
of ammonia and of nitric acid indicate that there exists a dif-
ference of 25^ in favor of the latter combination. f

The Conditions Favorable to this change of form are :
presence of atmospheric air, moisture, heat above 12° and below
55° C. The activity increases with elevation of temperature
till 37° C. is reached, at which point the maximum nitrification
occurs; it then diminishes regularly till at 55° C. it ceases
altogether, the microbes losing all nitrifying power.:}:

The products of the phenomenon of putrefaction, like those
of all organic decomposition, are identical with the process of
combustion, with a difference only in time required and con-
sequent energy of the chemical action. We have already seen

* Warrington in Jottrtml of the Chetuical Society, Jan. 1S7S.
f Personal communication from Sir J. B. Lawes to the author,
t Wolff, Diingerlehre {^^xWn, 1SS3), p. 12.

128 HOCKS AND SOILS.

that in each case a residue of inorganic, non-combustible ma-
terial or ash must be the result. But the accomplishing of
this result through humification not only brings to the soil an
accession of atmospheric matter, but, since the mineral constit-
uents of plants are obtained often from great depths by the
penetrating roots, and the decay of the plant thus built occur-
ring comparatively near the surface, the process of necessity
results in the constant transfer of mineral matter from the sub-
soil, aecessible to but feiv plants, directly to the surface-soil, ivJiere
it becomes freely-soluble food azvaiting the demands of all agri-
cultural plants.

Another feature of the process of humification worthy of
note is the fact that the more rapid or complete the decomposi-
tion the greater is the resulting product of ash material, because
of the large amounts of water and of carbonic acid formed ;
the same cause increases the product of nitrogen and carbon,
while the quantity of hydrogen and oxygen is diminished.

In connection with this fact is the self-evident truth that the
nearer the surface the more perfect must be the decomposition,
because of the more free access of air. And atmospheric oxy-
gen not only furthers the decomposition, but facilitates the
transformation of nitrogen into ammonia and nitric acid.

It therefore follows that the deeper soil-strata and peat-de-
posits excluded from free atmospheric action contain vast
stores of the all-essential nitrogen, not converted into assimila-
ble form as ammonia or nitric acid, but remaining in an unutil-
izable form, awaiting the completion of its decomposition,
through artificial subjection to atmospheric action and conse-
quent conversion into plant-food.

Though ammonia salts and nitric acid are by far the chief
nitrogen-furnishing compounds among all sources of nutrition,
yet organic nitrogen cannot be asserted as being wholly inact-
ive or dormant ; the supply of food obtained from this source
is, however, so small as to pass almost unnoticed.

ORIGIN AND COMPOSITION OF SOILS. 1 29

II. Animals as a Source of the Organic Constituents

OF Soils.

All that has been recorded concerning the action of plant-
life and decomposition in supplying the organic matter present
in all agricultural soils might be repeated, with equal force and
applicability, in describing the function of animals in transform-
ing broken-down rock into true soils ; with this difference, how-
ever, that the organic matter thus conveyed to the soil by animal
life and death was not extracted from the atmosphere through
the life-function of the animal body, but passed first through
the intermediate stage of plant existence ; then entering the
animal system as food, to finally pass to the soil, there to be
subjected to the same influences acting on vegetable matter ;
to undergo like process of decay or decomposition with a final
formation of identical products.

One difference, not of kind but of degree, should, however, be
cited. Plants are characteristically carbonaceous in composi
tion, while animals are as distinctively nitrogenous. Carbohy
drates are the predominating constituents of the former, al
buminoids of the latter. It therefore necessarily follows that
although the decomposition of the two different classes of or-
ganisms results in the formation of the same class of com-
pounds, and putrid fermentation is a characteristic phenomenon
in both cases, it is a far more important occurrence with ani-
mal matter, because of the greater quantity of material sub-
jected to its action, and the consequent greater yield of the
typical products ammonia and nitric acid.

Another distinction should also be made between the meth-
ods by which plants and animals contribute to the organic
matter of the soil. Although with the former the procuring
of organic matter from the atmosphere as well as from the soil
direct is a distinctive life-function, the return or conveyance
of the material thus obtained to the soil is only accomplished
through death and decomposition.

On the other hand, though animal death and decay are no
less distinctive steps toward supplying the soil with its organic
matter than is the case with the vegetable world, the animal

T30 ROCKS AND SOILS.

possesses the further power of returning organic matter to the
soil as a direct result of the life-functions themselves.

Animals return to the soil that part of the organic matter
consumed as food but not assimilated by the system. This
effete matter, or excreta, both solid and liquid, becomes incor-
porated with the surface-soil, undergoes the same decomposi-
tion, and furnishes the same resulting products as is the case
with decaying animal or vegetable organisms.

Important as this excretion of organic matter by living ani-
mals has been, and continues to be, as a factor in supplying
soil with its quota of organic constituents, other and even
more impoitant results are accomplished through the energy
and activity of certain animal forms. Not by the addition to
the soil of effete or exhausted material, but by the direct ac-
tion of the animal on the soil itself in performing its life-func-
tions and fulfilling the destiny of its existence.

The Burrowing or Ploughing of certain Animals is of
a nature identical with the labors of the human ploughman, and
with results on the organic constituents of the soil commensu-
rate with the energy exerted. The importance of the labor
thus performed during the lapse of long periods of time can-
not appe?.r small when it is recalled that thereby are secured
the means of exposure to atmospheric action, resulting in oxida-
tion of carbonaceous and albuminous material, as well as the
mineral constituents of the soil.

Ants, moles, prairie-dogs and marmots are the animals whose
activity in this work has been most noteworth)'.

Concerning the labors of these last-named quadrupeds, in
teresting and important facts have just been brought to
light.*

It is reported that on the Caspian Steppes the burrowing of
these animals has brought to the surface within a few years
one cubic metre of earth per square metre of surface. Or over
large areas, not less than 30,000 cubic metres of earth have been
brought to the surface for every square kilometre of area;

* Mushketorf, Nature, Oct. 6, '87, p. 541.

OR/Giy A AW COMPOSITION OF SOILS. 13I

hundreds of square miles having been thus subjected to hteral
upheaval and pulverization.

Considerable as has been the influence thus exerted on the
ultimate organic content of the soil, it is but insignificant as
compared with another class of animal action exerted in a far
different way.

P2ARTH-WORMS have, through all geological time since their
arrival on the Earth, been steadily engaged in the conversion
of the inorganic soil into vegetable mould, as a life-function,
through the addition to it of the organic matter required for
the transformation.

The action of worms is of two kinds. First, chemical action
on the mineral constituents of soils by conveying to them or-
ganic matter of a humus character in the form of digestive
secretions ; and second, physical action on the soil-particles
by passing through the alimentary system of the animal.

The Secretion of Organic Acids in the Digestive Or-
gans OF Worms is thus described by Darwin :* " From the
contents of the intestines of worms, and from their castings be-
ing acid, it seems probable that the process of digestion induces
an analogous chemical change in the swallowed triturated and
half-decayed leaves. The large quantity of carbonate of lime se-
creted by the calciferous glands apparently serves to neutralize
the acids thus generated ; for the digestive fluid of worms will
not act unless it be alkaline. As the contents of the upper
part of their intestines are acid, the acidity can hardly be due
to the presence of uric acid. We may therefore conclude that
the acids in the alimentary canal of worms are formed during
the digestive process, and that probably they are nearly of the
same nature as those in ordinary humus."

The best experimental demonstration of the transformation
thus wrought in the composition and characteristics of the soil
is by Von Hensen.+

A vessel eighteen inches in diameter was filled with sand, the

* "The Formation of Vegetable Mould through the Action of Worms," p. 240.

\ Zeitschrift fur Wissenschaftliche, Zoologie, 1877, p. 36«.

132 KOCKS AXD SOILS.

latter bcingr strewn with leaves. Two worms were introduced ;
the leaves were quickly drawn into the burrows of the worms
to a depth of some three inches, and were partly consumed and
partly used as lining or as barrier* at the entrance to the bur-
rows. At the end of six weeks a uniform layer of sand one
centimetre in depth was converted into humus by having
passed through the alimentary canals of these two individuals.

Not only is organic matter conveyed to the soil as a product
of the digestive systems of worms, but the leaves drawn into
the burrows as food are, after being but partially digested, satu-
rated with intestinal and urinary secretions and mingled with
the soil. The latter thereupon becomes the dark, rich humus
so universally covering the surface of the Earth with its well-
defined protecting stratum.

The amount of organic matter thus directly or indirectly
added to the soil may be inferred from the fact that Darwin
estimates that the material annually brought to the surface by
worms is two tenths of an inch per acre ; equivalent to an aver-
age of 10.59 tons for each acre inhabited by worms.

No data exist for determining the exact difference in composi-
tion between the soil before and after subjection to this action.
But Darwin states the ammonia content of worm-casting to
be O.OiS^f, while the average amount of ammonia present in
common surface-soils as determined by Knopand Wolff* is
only 0.00056^0 It therefore appears that the action of worms
has increased the ammonia content of the soil acted on more
than threefold (321^) ; and the total amount of ammonia added
to the soil by this means would be represented by .01744^^ of
10.59 tons ! equivalent to an accession of 36,936 lbs. of ammonia
per acre. Yet ammonia is but one, and perhaps not the most
important, of the constituents directly conveyed to the soil
by the life-functions of worms. At present, however, we can
only surmise that the accession of other material is proportional
to the gain in ammonia.f

* Johnson, " How Crops Grow," p. 250.

■}• The chemical changes resulting through the action of worms on the soil are at
present being experimentally investigated under the direction of the author.

ORIGIN AND COMPOSITION OF SOILS. 1 33

This, be it borne in mind, is but a change \vrou<jht in one year,
and capable of yearly repetition. And, moreover, " the entire
mass of the mould on every field passes in the course of a few
years through their (the worms) alimentary canals." *

III. Composition of the Soil.

Having now reviewed the incorporation of organic matter
with the mineral matter, the result of which is the production
of a true agricultural soil, it becomes in order to consider more
intimately the chemical constitution of the combined material ;
first examining more carefully

A. COMPOSITION OF THE ATMOSPHERIC INGREDIENTS OF THE

SOIL.

As already noticed (page 125), humus, or the constituent of
soils derived from organic decomposition or from the life-func-
tion of animals and plants, is a complex material consisting of
a varying number of ingredients, all definite chemical com-
pounds, chief among them being recognized ulmin and ulmic
acid, humin and humic acid, crenic and apocrenic acid.

Ulmin and its acid compound are supposed to characterize
brown humus, while humin and humic acid are obtained from
dark or black humus. The composition of these bodies cannot
be stated as determined beyond doubt, and Johnson (" How
Crops Grow," p. 125) even doubts the existence of either humin
or ulmin as distinct from the corresponding acid though
later authorities + recognize the distinction.

The change from base to acid is, however, not a change in
composition, and is wrought by the action of a solution of
sodium carbonate in which the acid alone is soluble. These
compounds are not only products of organic decomposition, but
may be synthetically formed by the action of strong acids on
sugar, starch or cellulose.

The most reliable results of analyses establish the composi-
tion of these different humus compounds as follows :

* Darwin, p. 243.

f Mayer, Agriadturchemie, Bd. II. p. 67 ; Beilstein, Handbuch d. Organ.
Chem. p. 60S.

134

IWCKS AND SOILS.

Ulmin and Uhnic Acid.

Carbon, . . . . 67.1^ |
Hydrogen, .... 4-2^ >
Oxygen, 8.7^ )

Corresponding to

Htimin and Hnmic Acid.

Carbon, .... 64.4^ \
Hydrogen, .... 4-3^ \
Oxygen, . . . .31-3^)

Crenic Acid.

Carbon, 44-0^

Hydrogen,. . . . 5.5^

Nitrogen, .... 3.9^

Oxygen, .... 46.6^

Corresponding to
C.H,A. + 3HA

Corresponding to

P T-T O r>

Carbon, .
Hydrogen,
Nitrogen, .
Oxygen, .

Apocrcnic Acid.

. 34.4^

. 3-5^

3.0^

. 39.1^

Corresponding to
P T-T O ?

There are, aside from these humus compounds, others still less
known and the action of which is not yet understood ; among
them xylic acid, Cj.HjjO,,, saccharic acid, C„H,,0,,, glucinic
acid, C.^Hj^O,^, besides a brown humus acid containing carbon,
65.8^, and hydrogen, 6.25^, and a black humus acid yielding
carbon, 71.5^, and hydrogen, 5.85^.*

It is somewhat remarkable that the composition of these
compounds ^till remains shrouded in uncertainty ; the only
explanation being the extreme difficulty in obtaining them
sufficiently isolated and pure for analysis. It is perhaps par-
donable in agricultural chemists to still accept and quote the
authority of Mulder when the latest works on organic chemistry,
including Roscoe and Schorlemmer and Beilstein, venture no
formulae for these long-ago-recognized compounds.

* Beilstein, p. 6og.

ORIGIN AND COMPOSITION OF SOILS. 1 35

Yet Mulder's assertion, repeated by Johnson and others, that
the nitrogen detected by all of his anal)"ses of crenic and apo-
crenic acid was due to the presence of ammonia compounds,
probably ammonia salts, is irrational in the extreme, though
true no other explanation was then more tenable.

That any ammonia salt should have successfully \\ithstood
the action of caustic potash is not possible, since no known
organic nitrogen compound fails to yield ammonia through this
action ; while with most organic compounds caustic potash acts
rather with too great energy, so that the weaker alkali, mag-
nesia, is more frequently used for the purpose.

It is therefore far more reasonable, as explained by Mayer,^
to believe that the so-called crenic acid and apocrenic acid of hu-
mus are in reality organic nitrogen compounds. This being true,
the excessive insolubility and resistance of many soils (peat, for
instance, with a humus yielding as high as ^.y/c of nitrogen)
to the action of plants, and their worthlessness as sources of
plant-food nitrogen, is explained. When caustic potash fails in
reducing organic nitrogen to a soluble form, the efforts of the
growing plant must be hopeless indeed.

The Action of these Humus Compounds on the Inor-
ganic Constituents of the Soil is of no inconsiderable im-
portance. The ulmates, humates, crenates and apocrenates of
the alkalies, potash, soda and ammonia, are freely soluble in
water and must therefore serve as plant-food. A fact impor-
tant in its bearing on the conversion of insoluble silicates into
soluble compounds of the humus acids.f

The Nitrogen of the Soil may exist in three different and
distinct forms; i. As organic nitrogen combined with carbon,
hydrogen and oxygen (sulphur, phosphorus and chlorine may
also be present in the compounds). 2. As ammonia or ammo-
nia salts; 3. In the form of nitric acid.

The total amount of nitrogen present in average agricultural
soils is slight, varying from o.i to 0.3 per cent, although in peat
and humus from 4 to 5 per cent is not unknown.

* Agricullurchemie (Heidelberg, 1875). Bd. II. p. 69.
f Julien, Proceedings A. A. A. S. 1879, p. 311.

136 ROCKS AND SOILS.

Of these three forms only the two latter can be considered
as available nitrogen, and the former is of no value as plant-
food except as converted by decomposition into one of the
other forms mentioned. A transformation occurring but
slowly at best. The extremely inaccessible organic nitrogen
of soils is aptly described by Mayer as corresponding to the
nitrogen of mineral coal, also resulting through a process of
humification, and as being, so far as vegetation is concerned,
similar to insoluble phosphoric acid and potash.*

The Ammonia of the Soil exists, because of its affinity for
acids, exclusively as ammonia salts, the carbonate being most
prevalent. The entire quantity present at any one time is very-
slight, the extremes being 0.00014-0.001 per cent, with an aver-
age of o.ooo^yfc. Ammonia salts are, however, all soluble in
water, and therefore the quantity present is wholly available,
while the amount receives constant replenishing through or-
ganic decomposition.

Much ammonia is doubtless received from the air, chiefly ab-
sorbed by rain and thus conducted to the soil as an aqueous
solution, but either immediately combines with acids or is lost
by volatilization. The formation of ammonia through the pro-
cess of putrefaction, as already considered (page 127), remains
the most interesting source of vegetable nitrogen, inasmuch as
it supplies not only the ammonia assimilated by plants, but also
is the greatest supplier of the nitric acid resulting from the
process of nitrification.

The Conversion of Inaccessible Organic Nitrogen
INTO Ammonia has a most import-ant bearing on vegetable nu-
trition, not so much through its occurrence in natural soil-con-
stituents, but from the fact that the richest of all nitrogenous
natural fertilizers, urine, contains nitrogen only in the form of
urea, where it exists as combined organic nitrogen wholly in-
accessible as plant-food ; by decomposition, however, the urea,
N,H,CO, becomes transformed into ammonium carbonate,
(NHJjCOj, soluble plant-food.

N,H,CO + 2H,0 = (NH,),C03.

* Agriculturchemie, Bd. II. p. 70.

ORIGIN AND COMPOSITION OF SOILS. 1 3/

The transformation wrought is the result of the hfe function
of a micro-organism living only in presence of oxygen; and
Prof. Kellner of Komaba, Japan, has recently shown that the
transformation occurs only comparatively near the surface, sel-
dom deeper than 0.5 metre, since below this depth sufficient
oxygen for supporting the life of the transforming organisms is
not present. A most important fact when taken in consider-
ation with the truth that the transformation is not of immedi-
ate but rather slow occurrence, and that the soluble urea must
therefore often be carried by heavy rains far deeper in the soil
than its transformation into ammonium carbonate is possible;
therefore, being wholly insoluble, must be a total loss so far as
a source of vegetable nitrogen is concerned.*

The Nitric Acid of the Soil, as already recorded, is chief-
ly a product of organic decompositioji existing in the soil, com-
bined with potassium sodium, ammonium or calcium to form
nitrates of these most common soil-bases, and resulting from
the transformation of ammonia by the action of living organ-
isms, through a process known as nitrification.

The total amount of nitric acid in agricultural soils is, ac-
cording to Wolff, slight^ and varies between the extremes
0.0006 and 0.03 per cent, with an average of .01502^. Small as
the quantity is, however, it plays a most conspicuous part in
the nutrition of all agricultural plants.

Since nitric acid, formed in the atmosphere through the ac-
tion of electricity, is, therefore, always present in traces as a
constituent of the air, and is most readily soluble in" water, it
follows as a matter of necessity that some nitric acid must find
its way to the soil as a constituent of rain-water, usually, how-
ever, combined with the ammonia likewise extracted from the
air. By far the greater quantity of soil nitric acid, however, is
of organic origin, and formed directly in the earth by decom-
position, passing through the intermediate stage of ammonia
formation.

This Process of Nitrification, already mentioned (page
127), resulting in the conversion of ammonia into nitric acid,

* Landwirthschaftliche Jahrbiicher, Bd. XV.

138 ROCKS AND sorr.s.

tkrough the action of living microbes, occurs only in the upper
strata of soil, where access of oxygen for supporting the exist-
ence of the acting organism is greatest ; and is of necessity in-
creased by the porosity of the soil and by exposing new sur-
faces to action.

The most recent Rothamstead experiments demonstrate
that little or no nitrification occurs in the subsoil ; 2-3 feet be-
ing evidently the extreme depth at which the phenomenon
occurs.* The nitric acid of the soil below this depth is doubt-
less carried thither in the drainage or by diffusion.

The depth at which nitrification may occur, however, is capa-
ble of considerable variation, not only because of the physical
condition of soil, and access of oxygen, but depends largely
on the character of the crop grown ; leguminous plants, like
vetch and clover, seeming to possess the property of consider-
ably increasing not only the depth at which the transformation
may occur, but also the activity of the nitrifying organisms.

To refer the occurrence back from effect to cause since the
leguminous plants are most fortunate in the amount of nitric
acid furnished them by the micro-organisms, it is a reasonable
inference to suppose that the leguminous plant in its turn fur-
nishes the most favorable conditions for the growth of the
microbes, or the proximity to the roots of legumes is their
most congenial habitat.f

Atmosphkric Nitrogen itself may also be subjected
TO the nitrification process, there seems every reason to
believe, although the author is aware of no assertion of the
fact. But nitrification and action on urea are not the only
functions of lower organisms effecting nitrogen compounds.
Berthelot has recently shown X that certain soils, both argilla-
ceous and sandy, possess the property of absorbing and fixing
atmospheric nitrogen, through the action of a living organism.

Five series of experiments were made with soils under as
many different conditions. The first soil was preserved in a

* Warrington, Journal Chem. Sot., Feb. 1887.
\ Miles, Agricultural Science, May 1887.

X BulUtin cle la Soci^t^ Chimique, Feb. 26 ; also Am. Journ. of Science, May
1886, p. 391.

ORIGIN AND COMPOSITION OF SOILS. 1 39

room, the second in tlic open field, but under shelter, the third
exposed on top of a tower 28 metres hii^h, and the fourth
was contained in hermetically closed flasks, while the fifth was
sterilized. In the first four cases, or, in other words, with all
soils not sterilized, there was a slow fixation of atmospheric
nitrocjen, independent of ammoniacal condensation, and of nit-
rification.

Each kind of soil was equally affected; and all locations
or conditions chosen. The compounds formed were complex,
insoluble amides, resembling those existing in living organisms ;
and must have resulted through the vital activity of the micro-
organisms present.

The reaction does not occur in cold weather, is manifest
throughout the growing season, but is prevented at tempera-
tures above 100^ C.

The amount of nitrogen becoming thus fixed by each hec-
tare of surface is equivalent, during one season, to 20 kg. for
yellow sand, 20.5 kg. for second sand and 35 kg. for clayey soil.

The chief interest and importance attached to these facts
seems to rest on the most reasonable supposition that nitrogen
thus extracted from the atmosphere may become actual plant-
food, and thus revolutionize previously-conceived ideas con-
cerning the ability of the plant to assimilate nitrogen of atmos-
pheric origin ; and explain many before mysterious facts con-
cerning vegetable nutrition. We have heretofore supposed
atmospheric nitrogen to be inaccessible to plants, unless con-
verted into nitric acid or ammonia and in these forms absorbed
by the soil. But now, though we still possess no evidence that
atmospheric nitrogen is direct food for plants, we find that it
becomes, by the action of living organisms, transformed into
organic nitrogen and is taken up by the soil in a form closely
resembling the forms of organic nitrogen already considered ;
and must, like them, be subjected to the action of tho.se forces
or beings through the activity of which organic nitrogen be-
comes converted into ammonia and nitric acid and thus finally
exists in accessible form for plant-assimilation.

The study of these organic nitrogen compounds of atmos-
pheric origin through their metamorphosis from atmospheric

I40 J^ OCA'S AND SOILS.

nitrogen to nitrogenous compounds containing accessible nitro-
gen remains a field for further research.

The Reverse of Nitrification is likewise a well-recog.
nized phenomenon. That is, the nitric acid formed by the ac-
tion of certain organisms on ammonia may, under certain con-
ditions, become re-tj'ansformed into ammonia. This process
results from the afifinity of nitric acid for soil-bases, chiefly al-
kalies and alkaline earths ; it therefore never exists uncombined
in the soil, but in the form of nitric-acid salts, particularly as
nitrates of potash, soda, lime and ammonia. And these com-
pounds by reduction lose their nitric acid, which again becomes
ammonia, and the bases combining with the oxygen remain be-
hind as oxides. The reaction occurs chiefly in the subsoil
stratum, where atmospheric oxygen finds less ready access, and
where, therefore, nitrification seldom occurs.

Other Ingredients of Atmospheric Origin exist as oc-
casional constituents of the soil, some of which are capable of
indirectly furnishing plant-food ; among them nitrous acid and
carbohydrates, decomposable into carbonic acid and water.
The carbonic acid thus formed is doubtless to a limited degree
a source of vegetable carbon ; but its chief action is through
combining to form carbonates or bicarbonates, the importance
and action of which have been fully considered in Part Second.

B. non-atmospheric constituents of the soil.

These are of course wholly mineral. Nitric acid and ammo-
nia are equally mineral as distinguished from organic ; but
from the difficulty of separating them from organic compounds
from which they are generated, they have been considered with
their organic combinations under the classification of atmos-
pheric.

The soil must of necessity contain, in addition to the con-
stituents already considered, all the elements composing the
rocks through whose disintegration they were first formed and
on which they find a basis. As a matter of fact, therefore,
soils, or some soils, must contain the more than threescore of
elemental bodies existing in different rock-forms. But agricul-

ORIGIN AND COMPOSITION OF SOILS. I4I

turally considered, the soil is of a much simpler organization,
and in addition to those constituents already enumerated con-
tains but twelve substances recognized as entering into the com-
position of plants, and therefore important and essential com-
pounds of all agricultural soils.

These are, as they exist in the soil and are found in the plant,
mostly compound in nature, being either oxides or acids as
follows : potasa, soda, magnesia, lime, alumina, iron and man-
ganese oxides, sulphuric acid, phosphoric acid, silica, carbonic
acid, and chlorine.

The occurrence and characteristics of each require separate
discussion.

Potasa and Soda exist in the soil only combined with
acids, never in free condition. Most frequently the combina-
tion is with silicic acid to form silicates; the sodium exists
combined with chlorine to form the very abundant and widely,
distributed sodium chloride, common salt. With the excep-
tion of silicates, the potash and soda, and all alkali compounds,
of the soil are all readily soluble in water. The soil content of
these alkalies seldom rises above 3-4 per cent, of which total by
far the greater part is included among the insoluble silicates.

Lime is among the most variable of soil-constituents existing
in all proportions from barely detectable traces, to even 30^ in
certain soils of limestone regions. Uncombined calcium
oxide is of rare occurrence in the soil, it is more frequently
combined with carbonic acid, phosphoric acid, or sulphuric
acid, forming carbonates, phosphates or sulphates. With the
exception of the crenate, nitrate and sulphate, the salts of cal-
cium are wholly insoluble in pure water, and the latter even
with much difficulty.

Carbonates and phosphates are, however, soluble in waters
containing free carbonic acid, as is always the case with the
running and hygroscopic water of soils.

Lnne is of unusual importance as a soil-constituent, inasmuch
as it is not only a necessary ingredient of all plants, but exerts
a peculiar activity on the physical properties of the soil.

Magnesia is an invariable companion of lime as a soil-con-
stituent, since rocks containing the one as a rule contain the

142 KOCKS AND SOILS.

other. The most frequent form of occurrence is combuied as
carbonate, which is whoUy insohible in pure water but dissolved
by carbonic-acid waters, though to a less degree than is the
case with calcium carbonate.

Alumina is among the most abundant of soil-constituents,
particularly combined with silica to form silicate of alumina,
or common clay; alumina is estimated as embracing i6.66^ of
the entire Earth-crust. The silicate (clay) exerts its influence
chiefly on the physical properties of soils, and forms about 20fc
of the total soil-mass, wholly insoluble in water. Combined
with water to form the hydrate, and with sulphuric acid as sul-
phate, alumina forms slight quantities of soluble compounds,
the total amount of which is, however, hardly recognizable ex-
cept as traces.

Iron occurs not only in widely-varying proportions, but also
in greatly-diversified form as a soil-constituent. The total
quantity present as iron oxide is commonly not greater than 5^
nor less than 0.5^, though soils exist with as high as 30^ ;
these, however, are barren through excess, just as those con-
taining less than 0.5^ are sterile for lack of iron ; the latter
are chiefly marls, the former ochres.

The two forms in which iron fundamentally exists in the soil
are as the protoxide FeO and the sesquioxide Fe„03 ! ^'""^
the entire character and value of a soil may be dependent on
the question of the existence of one or of the other of these
two iron oxides.

The affinity of iron for oxygen is such (iron oxidizes so readily)
that the protoxide can exist only in the absence of sufficient
oxygen to form the higher oxide. Wherever access of abun-
dance of atmospheric air exists, there the sesquioxide is found;
but where this sufficiency is lacking, in the deeper soil-strata,
there the lower oxide is found ; seldom, however, in a free con-
dition, but combined with acids to form salt of the protoxide.

A most important fact, however, is the frequent reduction of
the higher to the lower oxide in the soil. Organic compounds
decomposing in presence of oxygen-containing compounds
possess the property of attracting the oxygen from the metallic
oxide, or reducing the same. This is the principle in the use

OKIGIX AXD COMPOSITIOX OF SOILS. 1 43

of charcoal in the smelting of metals. An identical process
occurs in the soil, where organic decomposition is constantly
taking place. The oxygen of the iron sesquioxide is attracted
to combine with carbon or other constituent organic matter to
form carbonic acid or other product of combustion or decom-
position, and instead of Fe^Oj. 2FeO is found, thus:

FeO\

I >0 = 2FeO + 0.
FeO/

The product, however, iron protoxide, immediately attracts
oxygen again from the air if this is present and re-forms the
sesquioxide, so that the process may go on indefinitely repeat-
ing itself.

The higher oxide combines readily with water to form hy-
drated iron oxide, or the red iron-rust so common, and noticed
so universally as a red deposit on soils or on the bottom of pools
or streams of water in iron-impregnated regions.

Agriculturally considered, the process of reduction is of great
importance, inasmuch as the lower oxide is poisonous to plant-
life and often renders large areas sterile and unproductive.
The remedy for which misfortune is, however, simply to hasten
the oxidation process by increasing the supply of accessible
oxygen, by ploughing, by burning or by the application of caus-
tic lime; the result being the rapid conversion of the poisonous
protoxide into the harmless sesquioxide.

This difficulty is most frequently met with after the first
ploughing of peat lands, or former swamps, or any land so com-
pact as to have enjoyed but slight access of air, and remedies
itself with thorough pulverization.

The iron compounds of the soil are chiefly sulphates, carbon-
ates, crenates or phosphates of the protoxide. Of these the
sulphate alone is soluble in water, but the carbonate is also
dissolved by soil-waters containing, as they do, absorbed car-
bonic acid.

Manganese in properties and compounds closely resembling
iron is a much more rare constituent of the soil, and plays a
far less considerable role. Its hydrate, the chief soil-com-
pound of manganese, is soluble only in carbonic-acid waters.

144 K OCR'S AND SOILS.

Silicic Acid (Silica) is, so far as abundance is concerned,
the chief constituent of all soils. The entire Earth-crust is esti-
mated as containing 66% of silica. It exists not only as free
silicic acid in the form of quartz and sand, but combines freely
with numerous bases to form silicates. These latter com-
pounds, with the exception of silicates of potash and soda, are
wholly insoluble in water, as is the free silica itself. The latter
is, however, soluble to a certain extent at the moment of dis-
placement from combination. The quantity of soluble silicic
acid present in the soil is never more than a mere trace, though
the total silica content of many sandy soils may be go%.

Phosphoric Acid is present as a rule only in minute quan-
tities, although it forms one of the most important and valua-
ble among all the soil-constituents ; it seldom forms more than
0.5^ of the total soil-mass. It exists only combined ; phos-
phates of lime, magnesia, iron and alumina being the most
prevalent forms, all of which are insoluble in water; but, with
the exception of the alumina compound, all are reduced to solu-
tion by the action of carbonic-acid water.

Sulphuric Acid occurs as a constituent of all soils, but
only in most minute quantities, and usually combined with
lime as calcium sulphate.

Carbonic Acid may exist in three different forms as a soil-
constituent. Combined with bases it forms the abundant car-
bonates ; in gaseous form as a part of the air of the soil, which
may be either of atmospheric origin, or result from organic
decomposition in the soil itself; or again, as a constituent of
the water in which it is so freely soluble, and in which form its
action as a solvent is so important.

Chlorine is a most wide-spread constituent of soils, com-
bined with bases to form chlorides. Sodium, magnesium and
potassium chlorides being the most prevalent forms, and all of
which are freely soluble in water. The total amount of chlo-
rine thus occurring in the soil is exceedingly slight, seldom ex-
ceeding o.oi^c of the entire mass.

In addition to the chemical constituents of the soil here
enumerated, other substances are more or less generally pres-
ent, nameh-, the water of soil and gases. But these arc not

ORIGIN AND COMPOSITION OF SOILS. 1 45

actual integral parts, but rather extraneous material, however
universal or important may be their occurrence and functions.
They are therefore considered not as soil-constituents, but
rather in the next chapter, among properties or characteristics
of soil.

The composition of the soil, the aggregation of facts here
discussed, are graphically collated and presented by the table
of soil-analyses included at the close of the volume.

One fact must, however, be forcibly presented through the
perusal of the material collected in this chapter, namely : The
constant and great variation in the composition not only of
different soils but of the same soil at different times and
under varying circumstances; variations even from day to day,
through constant change ; through decomposition and re-com-
bination the results of which tend to make the chemical com-
position of a given soil at a given time a most uncertain factor
in determining its treatment for different crops — so uncertain,
indeed, as to utterly overthrow Liebig's proposition to make
the chemical composition of soils, as determined by analysis,
the basis of rational culture.

Therefore, important as the composition of soils must be,
and dependent as successful husbandry must remain on a cor-
rect knowledge of the properties and uses of soil-constituents,
and the transformations and reactions occurring in the soil, the
greatest good is not to be derived through the mere study of
soil-composition, but through a knowledge of the ultimate re-
lations existing between soi/ and plant.

Study of the composition and methods of deriving and as-
similating nutriment from air and soil, must offer the only solu-
tion to the true and rational utilization of the substances
known to constitute the material cultivated as soil.

CHAPTER II.

CLASSIFICATION AND CHARACTERISTICS OF THE SOIL.

As demonstrated by the facts recorded in the preceding
chapter, the varieties of soil, so far as composition and proper-
ties are concerned, are almost innumerable. Yet we are defi-
cient in terms by which these differences may be expressed ex-
cept by actually describing the individual soil itself. Certain
terms are, however, used to designate soils of similar proper-
ties, and the various classifications thus devised are numerous.
Two, however, are more commonly resorted to, and describe
with considerable definiteness the peculiarities of the different
soils thus grouped together. These two different classifications
are based on distinct properties possessed by the soils em-
braced within the divisions made. The basis for the first sys-
tem being viethod of formation, and for the second physical
characteristics ; and both must be briefly considered.

I. Distinctions based on Origin or Method of
Formation.

Among the soils thus designated, two varieties are recog-
nized : Sedi:ntary or soils in place, and TRANSPORTED soils,
the latter being subdivided into Drift and Alluvial.

Sedentary Soils remain in place or in close proximity to
the rocks from which they were formed. Such soils, as a rule,
are comparatively shallow, and partake, of necessity, of the
character of the underlying rock-mass, an examination of which
is the truest criterion for determining their composition and
value.

Transported Soils have been subjected to geological
agencies, by whose action they have been removed from the
beds where they were originally formed, and deposited in new
localities, usually a sediment from flowing water, though
glaciers were a prevalent cause of the transportation, in which

CLASSIFICATIOX OF THE SOIL. 1 47

case suspension in water was not an inevitable prelude to final
deposition.

Drift Soils, in Europe commonly designated as " Diluvial,"
consist of small stones mixed with more or less finer material
resulting from disintegration and water-erosion, the pieces of
rock composing which have invariably been rounded by water
or erosive action. They are most commonly unstratified, and
may be composed of the most widely-diversified materials, con-
sisting of parts of all the rocks over the entire region traversed
by the transporting glacier.

Alluvial Soils embrace all soils of water-deposition, fresh
or salt, consisting of finely-abraded material resulting from
erosive action. They are usually more or less stratified because
of difference in density, the larger and heavier particles being
at the bottom of the deposit. They are the most fertile of
soils because of the fineness of division or pulverization, and
the fact of precipitation from waters containing the more solu-
ble constituents of the soil and rock areas over which they
have passed or through which they have permeated. They
embrace river " bottoms" and delta formations, and are in con-
stant process of deposition to-day.

Soils are of course not necessarily composed of either of
these particular varieties, but frequently consist of mixtures of
any or all of them ; or more commonly all the kinds may exist
quite distinct but in close proximity to each other; this being
particularly the case in the Connecticut Valley, where the sed-
entary soils are of easily disintegrated New Red Sandstone
origin.

II. Soil-distinction based on Physical Charac-
teristics.

Gravel consists of unweathered bits of rock, smoothed and
more or less worn by water-action, and including varying
quantities of fine earth not usually exceeding 30^ of the entire
mass.

The larger the proportion of stone the less the agricultural
value, both through difificulty of working and absence of

148 A' OCA'S AND SOILS.

nutriment ; the latter may, however, not be wanting if the
rock is of an easily-weathering variety ; and the disadvantage
of cultivation may be surmounted by utilization for grazing,
vineyard or forestry purposes.

Sandy Soil embraces those soils containing 80,'^ or over
of pure sand. The origin of this variety of soil is usually
traceable to the weathering of sandstone or conglomerate.
The older rock- formations, as gray wacke and variegated sand-
stone, furnish a product richer in alkalies, while the younger
rocks yield more quartz-sand. The latter with calcareous sand
increase the barrenness of the soil not only through absence
of plant-food, but through the absence of the necessary physical
properties of cohesion and absorption of water.

But sandy soil may consist of a variety of materials besides
quartz-sand. Lime sand, consisting of calcium carbonate,
greensand containing considerable quantities of silicate of
potash and phosphate of lime, as well as more or less impor-
tant amounts of iron oxide, may be present in sandy soil and
give it an enviable fertility.

ClaY Soil is that containing at least 60;^ of clay to-
gether with varying proportions of sand, of amorphous silica,
and products of weathering. It may originate in the disinte-
gration of a vast number of different rocks ; feldspar-oligoclase
slates and micaceous rocks being the chief clay-formers.

It exists in the finest possible state of division, is cohesive,
and often in wet localities exceedingly tenacious, being capable
of drying to an almost rock like and unworkable consistency ;
and through the contraction necessarily following, clay areas are
often traversed and intersected by deep and wide cracks or
clefts causing considerable damage to vegetation through
tearing and destruction of roots.

Clays are exceedingly impermeable to water, and therefore,
unless lying on a porous subsoil, are apt to dry slowly and
be wet and cold. Clay soils containing from 60-80 per cent of
clay form as a rule most valuable and productive soils, yield
good crops of all the more common agricultural plants, partic-
ularly wheat, roots, clover and grass. Those soils containing
between 80 and 90 per cent of clay have a diminished utility,

CLASSIFICATION OF THE SOIL. 1 49

but yield profitable returns of wheat, clover, buckwheat and
horse-beans. While more than gof^ of clay reduces the limits of
successful cultivation because of the difficulty of working and
danger from excess of water.

Loam Soils comprise those soils ranging between sand and
clay, and possessing more or less of each of these two constitu-
ents. The amount of finest weathering product or loam varies
from 30 to 50 per cent in addition to which sand, clay, lime
and the different products of rock-decomposition are present.
The properties of loam soils partake to a greater or less de-
gree of the characteristics of sand and of clay as the proportion
of these constituents is much or little. These variations are
designated Heavy clay loam with 10 to 25 per cent of
sand ; clay loam with 25 to 40 per cent of sand ; loam with 40
to 60 per cent of sand ; sandy loam with 60 to 75 per cent of
sand ; light sandy loam with 75 to 90 per cent of sand ; while
soils with less than 10 per cent of loam are either sand or clay
as the case may be. The term loam is therefore a most indefi-
nite characterization of a soil without the qualifying prefix
* sandy " or " clayey."

Marl as a distinct variety of soil, is a much more definite
term, and applies to all calcareous clays ; the proportion of
carbonate of lime, however, may not fall below 15^, nor
the quantity of clay rise above 75,^. The name is com-
monly applied to certain formations containing much shell-
lime and considerable quantities of greensand, in which case
the material is extensively used as a fertilizer, but is, however,
incorrectly designated.

Lime Soils contain, as the name implies, calcium carbonate
as a predominating ingredient, the proportion of which may
rise above 75^ although the usual quantity is under 50^. In-
deed the soil is more frequently designated as " calcareous "
clay loam or sand.

Salt Soil is a term applied to soil containing considerable
quantities of soluble salts, usually of lime or of soda, and em-
braces soils of little or no fertility like the alkaline plains of
Arizona. They are not infrequently, however, rendered fertile
by artificial application of water.

150 ROCKS AND SOILS.

Peat, Muck, or Humus Soils, all characterized by the pres-
ence of humus of vegetable origin, are, however, distinguished
according to conditions of formation. Peat includes soils re-
sulting from partial decay of vegetable matter under water, the
product being compact but fibrous and forming fuel. Muck
results under like conditions, but is less compact, not fibrous,
and is easily pulverized on drying.

Humus soil, or vegetable vwuld, is the product of vegetable
decomposition without inundation. The amount of humus in
these soils may amount to 70^^' of their dry matter.

Othkr Distinctions of^Soil, more or less generally recog-
nized, exist, made with reference to location as regards tillings :
Arable soil or tilth, being the upper stratum or portion to
which fertilizers are applied, in which the seed is planted and
which forms the theatre of most farm operations. Beneath
this comes the Subsoil into which the roots of many crops pen-
etrate, and which possesses usually the character of the tilth
before subjected to cultivation. Most soils rest or repose on a
stratum of dense tenacious clay, being gradually reconverted
to rock by pressure and the action of alkaline silicates and
humates penetrating from above ; a formation appropriately
termed Hardpan.

III. Soil-estimation.

These distinctions drawn between different soils because of
various characteristics or physical peculiarities are based not
alone on mere obvious difTerences, these being wholly insufii-
cient. The distinctions are made because of actual and
demonstrable differences, either chemical or ph\-sical, deter-
mined by definite examination or subjection to fixed methods
of inquiry yielding exact results. As all differences among
soils are necessarily either chemical or physical, so the methods
of inquiry or estimation may be directed toward detecting
either chemical or physical proportions.

Our methods of analysis are therefore either chemical or
physical. For the distinctions forming the basis of soil-classi-
fication, however, only

Fig. 15.— Noebel's Analysis-of-soil Apparatus. (Jc /ace fnge j^i.)

CLASSIFICATION OF THE SOIL. Igf

Physical Analysis of the Soil is required or resorted to.

The method is based on difference in specific gravity, de-
tected by suspension in water.

Solid substances of different specific gravities agitated in
water become stratified, on being allowed to settle ; the
heavier at the bottom. In like manner soil or gravel subjected
to the action of the currents of running streams becomes grad-
ually deposited, the heavier first, or up stream, from the finer
and lighter particles.

Nobel's apparatus, most frequently used for the mechanical
analysis of soils, is simply an apparatus consisting of a series of
vessels graduated in size and all connected, through which a
known volume of water containing a definite weight of soil is
allowed to pass and become deposited in the successive vessels
for a fixed length of time.

The accompanying illustration from a photograph graphi-
cally presents the process as conducted in most agricultural
chemical laboratories.

The volumes of the four different conical vessels in the series
maintain definite proportions to each other as follows :

l' : 2' : 3' : 4' = I : 8 : 27: 64

The apparatus is so graduated that in 20 minutes 9 litres of
water, in which a known weight of soil has been thoroughly
suspended by boiling, will pass. At the expiration of the
specified time the current is stopped and the finest or most
buoyant portion of soil has passed entirely through the appa-
ratus into a vessel intended for its reception, and standing
several hours until wholly precipitated, is dried, weighed, and
designated as No 5 ; the contents of the four conical vessels
are treated in like manner, the smallest being known as No. i.
The result of the process will be the separation of the origi-
nal sample of soil into five different kinds or degrees of fineness:
No. I. Gravel, rock-fragments.
" 2. Coarse sand.
" 3. Sand.
" 4. Fine sand.
" 5. Silt or impalpable matter.

152 Ji OCR'S AA'D SOILS.

The separation thus effected is in many respects faulty, but
serves the general purpose of determining the relative propor-
tions of the different conditions of the soil-making material of
any given locality.

CHAPTER II.

CHARACTERISTICS OF SOILS.

Soil characteristics or properties must of necessity be of two
kinds ; either chemical or physical. The former, dealing
with the internal composition of the soil, have been already
considered in that connection ; the latter in contradistinction
may be described as relating to the external or visible properties
of the soil, including its position, porosity, cohesiv^ness, its tem-
perature, and its wetness or dryness. Characteristics of the
utmost importance as related to the growth of plants, and far
less under the control of the farmer than the mere chemical
composition of the soil, which can be easily changed at will.
The amount of actual plant-food present in a soil is of second-
ary consideration as compared with the facts of natural wet-
ness, cold or density, on which conditions the growth of plants,
the cost of working and the action of fertilizers so largely
depend.

These physical properties will be reviewed in their relations
to the growth and nutrition of plants and influence on soil man-
agement under the following division :

{I. Weight and Specific Gravity.
2. Color and Structure.
3. Behavior toward Water.

( I. " " Heat.

•< 2. The Soil and Electricity.
( 3. Behavior toward Gases.

I. Weight and Specific Gravity of Soils.

Both the absolute weight and specific gravity of a soil ob-
viously depend o!v the density of the same, an exceedinulv

CHARACTERISTICS OF THE SOIL. 1 53

variable quantity; and as a matter of fact neither property fur-
nishes anything hke a definite factor for determining the
nutritive content of the mass.

The Absolute Weight of the Soil varies of course ma-
terially with the porosity and with the character of its min-
eral constituents and amount of organic matter present. The
average absolute weight of natural soil of the field is about 75
lbs. per cubic foot.

The results of Schiibler's investigations are as follows :

weight, in pounds, of I CUBIC foot of dry soil.

Sand, no

Sand and clay, .... 96
Common arable soil, . 80-90

Heavy clay, 75

Vegetable mould, ... 78
Peat, 30-50

The Specific Gravity of most soils existing in the porous
condition of cultivated soil will be represented by an average
of 1.2, though few soils not lying at the surface of cultivated
fields will fall below 2. Schone's experiments with soils reck-
oned as solid masses give the following results :

SOIL specific gravities.

Humus soil from Orenburg, 2.53

Clay soil, 2.65

Sand soil, 2.67

Lime soil from Jena, 2.71

These results correspond with the specific gravities of the
predominating minerals constituting the soils, as follows:

Specific gravity of Quartz, 2.(:i^

" " Orthoclase, 2.55

" " Oligoclase 2.65

" " Labradorite, 2.70

" " Mica, 2.8-3.1

" " Augite, 2.9-3.5

" " Calc Spar, 2.7

" " Hornblende, .... 2.9-3.4

" " Dolomite 2.0

154 ROCK'S AND SOILS.

Specific gravity of Dry Clay, 2.5

" " Kaolin, 2.2

" " Gypsum, 2.26-2.4

From these facts it will be instantly recognized that the so-
called "light soils" are the heaviest of all, while the commonly
designated "heavy" clay is lighter than any but soils of chiefly
organic origin. The terms then are not applied because of act-
ual weight, and simply imply "easy " or " hard " to work.

II. Structure and Color.

The Color of the son. depends exclusively on its compo-
sition ; humus, for instance, forming a nearly black soil, while
sand or silica gives a very light yellow, and iron oxide produces
a red color. The matter of color is therefore of some impor-
tance as indicating the composition of the soil. But its chief
influence is through the action of different colors as absorbers
of heat, the darker soils having, other things being equal, the
highest absorptive power toward solar heat as demonstrated
through the earlier disappearance of the winter's snows from
these soils, and the efficacy of applying muck to the surface of
the snow in the spring whereby an earlier preparation of the soil
for cultivation is gained.

Soil-structure, under which term is implied the porosity
or state of division of the soil, is of the greatest importance in
influencing the results of cultivation. Indeed the fertility of
the soil is largely due to its porosity and thus thorough subjec-
tion to the action of atmosphere and moisture. The chief dif-
ference between bare quartz rock and sand being the difference
in pulverization whereby cultivation and growth of plants in
presence of abundance of water is rendered possible. And it
is a fully accepted fact that, other things being equal, that soil
is invariably most fertile which exists in the finest state of di-
vision, whose particles are the smallest.

Plants assimilate food only front solution, and the rapidity
of solution in the soil or elsewhere is in direct ratio to the
surface exposed to the action of the dissolving medium ; a
fact resting on the simple truth that the greater the surface

CHARACTERISTICS OF THE SOIL 155

exposed to any action, the greater must jc the product of tliat
action.

It must be borne in mind, however, that this very fineness
of the soil-particles renders it more susceptible to the impact-
ing influences of nature, or to cohesion, against which, however,
the process of cultivation is aimed, greatly abetted by the action
of frost, which tends to loosen the soil-particles and render the
mass more porous. And with the increase in porosity the ac-
tivity of the atmospheric influences exerting themselves against
the soil is increased.

The structure of the soil should also obviously be such as to
allow of self-drainage, or freeing from a superabundance of
surface-water.

III. Behavior of the Soil toward Water.

No property possessed by soils can be of greater direct in-
fluence on the growth of plants than the relations existing be-
tween the soil and the water which permeates it. For not
only is the water essential to the production of assimilable plant-
food, but the circulation of fluids in the plant itself is directly
and wholly dependent on the supply of water extracted from
the soil through the roots.

Imbibition, or the Water Capacity of the Soil, varies
greatly with diiTerent soils and determines to a great degree
their capability of supporting vegetation. The water capacity
of a soil is its ability to retain a definite quantity of water by
absorption without losing it or becoming super-saturated. Sat-
uration being indicated by the dropping or draining away of
the excess not held by the soil. This property of necessity
depends on the volume of air-space in the soil into which the
water can enter and exclude the air. The water capacity of
different soils as determined by Meister is as follows:

Clay soil imbibes 50.0 per cent of water.

Loam soil " 60.1 " "

Humus soil " 70.3 " "

Peat soil " 63.7

Garden soil " 69.0 " "

156 ROCKS AND SOILS.

Lime soil imbibes 54.9 per cent of water.

Chalk soil " 49.5

Gypsum soil " 52.4 " "

Sand soil imbibes (82,^^ sand) 45.4 " "

(64^ sand) 65.2

Quartz-sand imbibes 46.4 " "

It therefore appears that the pure mineral soils vary but
slightly, while the water capacity of soils seems to depend on
the proportion of organic matter present, and to vary with an
approximately fixed ratio.

So far as matter of practical value is concerned, however,
these results are of little value, inasmuch as they were obtained
under such conditions as cultivated soil in nature is never sub-
jected to. Soils are seldom if ever actually saturated with
water, because there is usually an outlet at the bottom for all
that is added at the surface ; and, moreover, the estimations
were made with so shallow portions of soil that the height of
the column of water was very slight, and gravity therefore
reduced to a minimum never actually existing in the soil.

Mayer first pointed out this inaccuracy, and undertook its
remedy.* He subjected columns of soil one metre in height
to experiment, and obtained what he designates the absolute
water capacity, in contradistinction to the former or full or
greatest zvater capacity. A noteworthy difference was thus
demonstrated. His results were expressed as follows :

WATER CAPACITY.

"Full"

" Absolute ".

Quartz.

Clay.

Sawdust.

Heavy spar.

per cent 49.0

46.0

76.4

39-2

. " 13-7

24-5

45.6

II. 7

By these experiments it became at once apparent that the
absolute water capacity of the .soil is far smaller than had for-
merly been considered its capacity; and it was further demon-
strated that the capacity varied greatly with the structure of the
soil, increasing in a fixed ratio with the porosity.

* Agriculturc/iemie, Bd. II. p. 143.

CHARACTERISTICS OF THE SOIL. 157

The Permeability of the Soil is its property of allowing
the passage or percolation of water ; a property of greatest im-
portance agriculturally, and varying widely with different soils.
The percolation must of necessity be proportional to the po-
rosity of the soil, and therefore is governed by the proportion
of fine earth humus or clay substance present, while as a natu-
ral consequence sand ranks as the most permeable of soils.

The chemical composition of the soil is also not without in-
fluence on the water percolation since it is known that the
property is decreased by addition of lime. Either excess of
activity of soil toward percolation is equally objectionable.
Too great a porosity allows the passage of waters and nutri-
ment through the soil so rapidly that much of the benefit for
the plant is lost ; while, on the other hand, insufificient per-
colation is followed by excess of surface-water and consequent
damage to the growing crop.

The Capillary Water of the Soil is most closely allied
to its percolating power, since all waters in the soil are gov-
erned in their movements by what is known as capillary force,
which, however, only manifests itself between bodies of differ-
ent degrees of moisture, the movement being as a rule from
the more moist to the more dry substance. The movement of
oil in a lamp wick is the most apt illustration of the principle;
and the soil answers the purpose of the wick, the waters of the
lower strata corresponding to the oil, and the surface evapora-
tion into the dryer atmosphere being the motive power which
keeps the force in action. Liebenberg has shown, however,
that the action in the soil may be either upwards or downwards
according as the atmosphere is dry or supplies soil-saturating
rain.

The force is but a manifestation of surface attraction, the
same as witnessed in the rising of liquids against the sides of
narrow tubes in which they are confined ; and the movement,
wherever it occurs, is but the passage of the fluid through in-
finitely small or capiUary tubes. Meisner* has experimentally

* M&isn&r, Ja/tresbericht fiir Agriculturcht'ffiic, 1859-60, p. 42; also Mayer, Bd.
II. p. 150.

158 HOCK'S AND SOILS.

demonstrated the relative capillary attraction of different soils
under like conditions ; the height to which water rose in nar-
row fTlass tubes filled with various soils and dipped at the low-
er end in water being measured in mm, and compared side by-
side.

Clay soil. . . .

Humus

Garden earth
Quartz sand

Peat

Sand soil.. . .
Gypsum. . .
Chalk soil... .

\^ hour.

340
400
290
440
260
450
120
60

S)4t hpurs.

IIOO
1 100
950
920
500
620
400
330

6)^ hours.

1 1 50
1 1 40
900
970
570
660
400
540

2iJ^ hours.

2000

1770

1610

II70

1 140

900

820

700

These results show that clay soil is most freely subjected to
capillary action, closely followed by humus, while the purely
mineral soils possess of all the least capillary power. The fine-
ness of division seems to control the soil capillarity; and,
moreover, great difference is noticed in the rapidity of action
and as a rule the more rapid the force manifests itself, the less
is the ultimate capillarity of the soil. The definite relation be-
tween rapidity of capillary action on the fineness of the soil
acted on is graphically shown by the researches of Haberlan-,*
who subjected soils of different degrees of fineness to capillary
action for varying lengths of time with results as follows :

Time ALLrv/ED.

^ hour.
I hour.

3 hours

4 hours
8 hours

1 day. .

2 days.

3 days.
6 days

Heightof Water Column

IN MM.

Coarse soil. Fine soil.

50

135

62

174

71

223

83

279

114

409

130

453

140

506

150

524

159

543

Gohren, Agricnltiirchemie (Leipzig, 1877), Bd. I. p. 89.

CHARACTERISTICS OF THE SOIL 1 59

The amount of capillarity, or height abo\e the water source,
thus measured would indicate that when the force depends
wholly on subterranean waters the height of its manifestation
is not sufficient to be of great service to those plants whose
roots do not penetrate to the near vicinit}- of the permanent or
hydrostatic waters of the soil. This condition is, however, rare-
ly attained since the capillar^' waters are receiving constant
accessions from the atmosphere in the form of rain, which, not-
withstanding the percolating power of the soil and the action
of gravity, is kept moving upwards towards the surface by capil-
lary power, which thus serves directly to supply the growing
plant with this all-essential substance, but moreover brings to the
surface-soil, and within reach of the roots, constant accessions
of soluble plant-food, dissolved and brought upwards, by the
moving waters, from deeper strata.

On this capillary water, then, the plant must chiefly rel)- for
the moisture on vv-hich its life and growth depend, for rain-
water as such plays but an inferior part, inasmuch as there are
weeks during every growing season when no rain falls and the
crop is wholly dependent on the stored-up capillar^' water with-
in the soil. And not infrequently during periods of protracted
drouth the growth of the plant is directly propoitional to the
supply of capillar}' water to which it has access.

The water absorbed b}' the roots passes into the plant-circu-
lation, and by far the greater part is evaporated from the leaves,
which have little power of re-absorbing. Where the supply of
water is insufificient the plant wilts, and if the evaporation long
continues in excess of the supply obtained from the soil death
must ensue.

The quantity of water thus required and evaporated by dif-
ferent agricultural plants during the period of growth has been
found to be as follows :

I acre of Wheat exhales 409,832 lbs. of water.

" " Clover

ti

1,096,234 "

" " Sunflowers

(1

12,585,994 "

" " Cabbage

((

5,049,194 "

" " Grape-vines

u

730,733 "

" " Hops

((

4,445,021 "

l6o ROCKS AND SOILS.

Or for one million plants of different field grains (per hec-
tare*):

Rye 83.4890kg. Barley. ... 123.6710kg.

Wheat. .. 117.9920 " Oats 227.7760"

Dietrich estimates the amount of water thus exhaled by the
foliage of plants to vary from 250 to 400 times the weight of
dry organic matter formed during the same time, at which rates
one ton of green clover would during its growth and maturity
have extracted from the soil and exhaled into the atmosphere
from 25,000-40,000 lbs. of water; and clover is no exception
among foliaceous plants.

Davy concludes, as the result of experiment, that 100 lbs. of
harvested wheat is obtained as the result of the exhalation of
90,000 pounds of water.

Knop found that Indian corn exhaled during its period
of growth 36 times its total weight of water. It therefore ap-
pears, from all the evidence deducible, that the volume of wa-
ter required by the plant for its maturity is enormous; yet, as
we have seen, the capillary water of the soil is the direct source
of supply; and when this fails, detriment or total failure must
result to the crop.

It therefore becomes of the greatest moment to the farmer
to so conduct his operations that this water may be conserved
for time of need.

A most radical change has been brought about in the meth-
ods of farm practice in this respect, as the results of the inves-
tigations of Prof. Levi Stockbridge at the Massachusetts Agri-
cultural College Experiment Station in 1878, by which the
amount of evaporation from the soil itself, without the action
of plants, was determined, and also the effects of different
modes of treating the soil according to the quantity of water
evaporated.

Six boxes, of one cubic foot capacity each, were filled with
soil, by being driven into place, without disturbing its strata,
immediately after a rainfall of .78 of an inch. The soil was
from cultivated fields, two specimens each of sand, loam, heavy

* I hectare = approximately 2.47 acres; i kg. =2.2 lbs.

CHARACTERISTICS OF THE SOIU

i5r

loam and clay. The boxes having received water-tight bot-
toms were placed in a trench with the surfaces of contents level
with the ground.

One specimen of each variety of soil was then thoroughly
hoed and turned over each morning to a depth of four inches..
The experiment covered seven days, during which the weather
was warm, and the sky free from clouds. The average day-
temperature of the soil was 36° C, and of the air 35° C, while
the night temperature of the soil was 21.5°, and of the air 19.4° ;
the atmospheric humidity averaged 70.

At the expiration of seven days all specimens were re-
weighed and the loss by evaporation recorded, together with
the difference in weight between the cultivated and unculti-
vated specimens, with these results.

Kind of Soil.

Clay

Sandy loam,
Heavy loam

Tilled.

Untilled.

lbs. oz. lbs, oz.

5 5 6 14
3 3 i 7 8

6 13 i 7 13

Actual
difference.

lbs.
I

4
I

oz.
9

Difference
per acre.

barrels.
256

734
223

The average diurnal loss per acre was as follows :

Barrels per Acre

Tilled UntiUed
Clay 129 167

Sandy Loam 77 1S2

Heavy Loam 158 189

The average daily evaporation for all three soils was, there-
fore, for the tilled soils 121^ bbls. per acre and for the untilled
1 79 J bbls. per acre, or an average daily difference for the three
soils of 58 bbls. per acre saved to the soil by cultivation to a
depth of 4 inches.

Considerable as this quantity is, and important as is its bear-
ing on the management of growing crops, it should be borne in
mind that in nature the amount of total evaporation must be
far in excess of that demonstrated by the experiment, inas-
much as the soils treated were but one foot in depth and were
boxed in against all possibility of any access of capillary water
II

5

" 15

6

" 15

4

" II

5

u J2

4

162 A' OCA'S AND SOILS.

from the lower strata to take the place of that evaporated,
which would otherwise have been the case.

But another important fact is demonstrated by this experi-
ment. If cultivation prevents loss of water by evaporation,
absence of cultivation must aid the soil in freeing itself from
superabundance of surface-water. The experiment was there-
fore repeated to demonstrate this fact, the following results
being obtained from the same specimens of soil wet to satura-
tion :

Clay soil tilled lost 4 lbs. 4 oz.

" " untitled
Heavy Loam tilled "

untilled "
Sandy Loam tilled "

untilled

Drought and excess of moisture are the two extremes against
which the farmer has to contend, and against which his battle
is so often hopeless ; and they are very apt to follow each other
in the same season. These experiments demonstrate the means
of relief from both extremes.

Cultivation conserves soil-moisture. Lack of cultivation hastens
evaporation of soil-moisture. So obvious were the benefits ob-
tained that the facts demonstrated immediately found wide
application, and are to-day most successfully followed in prac-
tice.

The reason of the facts as deduced by experiment are simple.
Cultivation of the surface destroys the density, makes the soil
porous or breaks the capillary tubes through which the water
moves, and its passage is of necessity thus retarded. The more
perfect the capillarity the greater the surface evaporation, and
vice versa. And capillarity is always inversely proportional to
the porosity of the body subjected to its action.

The Drying Propensity of Soils is most intimately con-
nected with imbibition and capillary powers, but the rapidity
or susceptibility of soils to part with their hygroscopic water
varies greatly with different soils irrespective of capillarity, and
the changes resulting to the soil through this drying process
are very various and multiform.

CHARACTERISTICS OF THE SOIL. 163

Sand is known to be the most readily diyablc among soils,
that is, gives off the most water, in a given time, through evap-
oration, while clay and humus retain the absorbed water a much
longer time.

The rapidity of evaporation is proportional to the surface
exposed to action ; consequently the more porous the soil the
faster the evaporation provided that only the surface, or portion
actually exposed to atmospheric action, is concerned ; as a matter
of fact, however, all soils contain capillary zvater zuhich is not, for
reasons already explained, thus affected. But of two varieties
of soil exposed to the same conditions, that soil containing most
fine earth or humus, possessing an absorptive power for water,
gives off that water most rapidly and readily.

Since the evaporation of water is at the expense of heat, the
soil becomes cooled by the evaporation of much water. Be-
cause of this reduction of temperature, and more especially
through the 4oss of mass by exudation of water, evaporation
results in a condensation or contraction of mass or volume of
soil. The contraction is of course proportional to the volume
of water lost, and therefore affects the more retentive humus
soils most. This condensation is often very noteworthy. A
remarkable example of such a phenomenon on a large scale has
just occurred in the vicinity of Sapporo, Japan, where a large
marsh has been partially dried through the opening of an out-
let into the Ishikari River. The entire affected area, many
square miles in extent, has in the course of six months sunken
an average of two feet below its former level, and the trees with
which it was covered now stand with roots exposed and bare
which previously were often more than three feet beneath the
surface.

Absorption of Vapor of Water is a property possessed
to a certain degree by all soils, and is known as their hygroscopic
power. But the power is not only possessed to a comparatively
limited degree, but even the slight amount of moisture thus
gained by the soil is of little practical use to the plant. Indeed
a radical change has occurred in the opinion of agriculturists
concerning this matter during the last decade. And though
no less an authority than Johnson claims that "this property

r64 KOCKS AND SOILS.

of the soil is of the utmost aj^ricultural importance,"* the ex-
periments of Schiibler on which Johnson supports his assertion
were as long ago as 1876 pronounced " antiquated " f by Prof.
Mayer of Heidelberg, perhaps the highest authority, as he has
been the most tireless investigator, of the subject ; and the same
statement is later accepted and quoted by Dr. Gohren, director
of the Franz-Joseph Agricultural Institute at Vienna. :j: The
facts in the case seem to be these. Absorption only occurs
between bodies of different hygroscopic conditions : the drier
absoibs from the more moist, except in the case of bodies
possessing a chemical affinity for zvatcr; it therefore follows
that soil only absorbs moisture from the air luhen it is drier than
the air.

" Only dry soil is capable of utilizing its hygroscopic property
for the absorption of atmospheric moisture ;"§ and the experi-
ments of Mayer, undertaken to ascertain whether natural and
artificial soils exhausted of water by plant exhalation possess
the power of condensation of atmospheric vapor, give conclu-
sively negative results. " These experiments," says the inves-
tigator, " all show that the actually occurring condensation is
of no avail to the plant, because this is far too much reduced
for lack of water before the condensation actually sets in."||

Moreover, all recent experiments show that the condensing
property of the soil is but slight, not greater than that of other
similar porous bodies, and has been held in much too high es-
teem. The famous experiments of Schiibler, on which much
erroneous teaching has been based, are to be honored for the
initiative they made, and not for their correctness in the light
of subsequent development. They were made under entirely
artificial conditions wholly impossible in nature, and leading to
most erroneous deductions. The soils treated were dried at
the boiling-point of water till the last trace of liquid had been
vaporized, then they were cooled and exposed to an atmos-
phere artificially saturated with moisture. Of course they im-
mediately absorbed large quantities of vapor of water and re-

* " How Crops Feed," page 161. § 1. c. Bd. II p. 134.

t 1. c. Bd. II. p. 142. II 1. c. Bd. II. p. 134.

X Agriculture hemic, Bd. I. p. 92.

CHARACTERISTICS OF THE SOIL. 165

taincd the same condensed as hygroscopic water. Any sub-
stance would have done the same; even a cut diamond would
have increased in weight under like conditions. Yet the carbon
of the latter is just as accessible for plant-food, as the moisture
absorbed under such conditions is a natural resource for the
plant in time of need.

The Water Solutions of the Son. contain all of the soil
material existing in an immediately assimilable condition for
the plant ; their composition and amount, in other words the
action of soil waters on the plant-food constituents present,
become, therefore, of the greatest value in determining the a"--
ricultural characteristics and value of the soil.

Indeed, most cultivated soils yield water solutions contain-
ing more of each of the elements of fertility than would suffice
to supply the necessities of one crop of any agricultural plant
or more than analysis shows to be present in any crop grown*
on the same soil.

A fact utterly at variance with and overthrowing Liebig's
once widely accepted theory that water dissolved none of the
potash, silica, ammonia or phosphoric acid of the soil ; and that
none of the elements of plant-nutrition was taken from the soil
by the action of water ; but rather all these substances were ex-
tracted or absorbed by the soil from solution. f

The present knowledge of the action of soil-waters toward
soluble elements of nutrition is the result of the use of the
lysimeter in investigating the question in place oi'' funnels full
of soil " employed by Liebig.

As the result of twenty experiments with as many different
specimens of soil, Hoffmann concluded that the quantity of
matter dissolved from the soil by water varied between 0.242 and
0.0205 percent of the dry earth ; of which, however, from 0.194
to 0.0137 per cent was organic matter. These results, however,
are but partially correct as indicators of the real action of water
on the nutritive soil-constituents, inasmuch as no soil gives up
all its soluble plant- food at one time, and moreover the presence

* Gohren, Hoffmann's Jahrb. iihcr die Fortschritte der Ag. Cke/n., Bd. VI. p. 7.
f Chem Briefen, 6te Ausg. p. 350.

1 66 A OCA'S AJVD SOILS.

and action of carbonic acid in the water varies and cannot be
definitely determined in a given case; also the presence of other
acids and their salts makes the actual phenomena occurring
naturally in the soil quite different from the results attained
experimentally by the use of pure or even running water.

Far more impossible yet is it to determine by this means the
actual amount of plant-food accessible during an entire growing
season. The action of plant-roots, of temperature, and of rain-
fall, all most inconstant factors, must seriously vitiate any at-
tempted calculation of the possibilities of a given soil for a defi-
nite period.*

CHAPTER III.
CHARACTERISTICS OF SOILS— {Cotttznued.)

I. The Relations between the Soil and Heat.

The warmth of the soil is necessarily of the greatest influence
and importance in its bearings on the production of crops ; the
entire growth of the plant, from the germination of the seed to
the ripening of the fruit and the gathering of the harvest, being
to a very great degree dependent on temperature.

The Sources of the Heat of the Soil are three:
namely, solar heat, as the sun's rays ; heat of chemical decom-
position within the soil; and the original or plutonic heat of
the Earth, proceeding from the still molten Earth interior.

The latter source though great in itself yet is so removed
from the surface, and the radiation there is so rapid, that this
heat is of no considerable value to the plant. The heat of
decomposition, though considerable, in soils rich in organic
matter, occurs only in the presence of comparatively high tem-
peratures, and is therefore not manifest except in soils not
needing its action to influence their behavior toward vegeta-
tion. The sun, therefore, remains the only source of heat of

* For composition of soil solutions see Appendix, Tables I, II and III.

CHARACTERISTICS OF THE SOIL. 1 6/

material importance as related to the production of plants from
the soil. The soil-temperature, however, whatever its origin,
is, to a greater or less degree, modified by numerous con-
ditions.

The Color of the Soil is among the chief of these
modifying influences. Since the solar heat influences the soil-
temperature in proportion to its absorption and radiation, that
soil absorbing most and radiating fewest rays must, other
things being equal, attain the highest temperature. Black
being the color possessing this property in the highest degree,
it follows that the darker the color of a given soil the warmer
it must be.

Humboldt records the temperature of a white and of a black
sand situated side by side as respectively 40° C. and 54.2° C.
The illustrations of the same fact are numerous and explain
the reason why snow always disappears first where sprinkled
with soot ; fruit ripens earliest on dark-colored hillsides. As a
matter of practical importance the difference thus often mani-
fested is of no little moment, a difference of from 8 to 14 days
in the ripening of potatoes, melons, grapes, and other crops
having been secured by a difference in the color of soils other-
wise equally suited to the needs of the crop cultivated.

Oemler has compared the temperatures of different soils
with these results :

Ratio to moor peat.

Moor peat 30.5° C. 95.3:100

"""^"^ -9°°C. 93.2:100

Sandyhumus 28.4° C. 92.9:100

Soil colored with Fe^Oa 28.3° C. go 6 ■ 100

Humus loam 26.2° C. g

Humus clay 26.6° C. 86^1 i 100

Loam 26.2°C. 82.0:100

Clay 25.0= C. g^^. jQQ

Sa"d 25.9°C. jQQ

Chalk 23. S' C.

The most graphic presentation of the exact influence of
color on soil-temperature is furnished by Schiibler, who treated
the surface of different soils alternately with a coating of lamp-
black and of magnesia, whereby black and white surfaces were

i68

ROCKS AND SOILS

Vhite.

Black.

Difference

•3°C.

50.9° C.

7.6° C.

.3°C.

51.1° C.

7.8° C.

.5°C.

51-3° C.

7.8° c.

.9°C.

50.5° c.

7.6° c.

.6° C.

49.4° c.

6.8° C.

.3°C.

48.9° c.

7.6° C.

.9°C.

50.5" c.

7.6° C.

respectively obtained for each variety of soil, and the tempera-
ture then recorded, as follows:

Kind of Soil. \

Quartz sand, i 43

Quartz sand, 2 43

Gypsum 43

Fine lime soil 42

Humus 42

Clay 41

Field-soil (Jena) 42

It therefore appears that a mere difference in color is capa-
ble of producing an average difference of over 7° in soil-tem-
perature.

The Specific Heat of the Soil is a most important
factor in determining the ease with which a soil receives and
retains solar heat. The less the specific heat, the greater the
susceptibility of the soil to the accession of heat from exter-
nal sources. The specific heat of the soil is usually between
0.20° and 0.25°; while that of water is 1°, or four to five
times as high. It therefore follows that

The Moisture of the Soil possesses Great Influ-
E^'CE ON THE SoiL-TEMPERATURE : So much influence, in-
deed, that a dry light-colored soil may attain a greater degree
of warmth than a moist dark-colored one.

Liebenberg experimented on the specific heat of many dif-
ferent soils with the following results ; the soils all being dried
at 100° C. :

Coarse Tertiary sand 1.268

Fine " " 0.275

Coarse Diluvial " o. 191

Fine " " 0.160

Lime sand 0.188

Diluvial loam o. 220

" marl 0.249

Loess loam o. 259

Loess marl o. 284

Humus loess loam 0.310

Weathered porphyry 0.209

granite 0.301

Shell-lime soil 0.339

Tertiary clay o. 160

Taken in connection with the fact that the experiments of
Plattner, made at Innsbruck in Tyrol, demonstrate that, in
that region at least, no soils with a specific heat below 0.22 are
fruitful, these results are of much value, and prove how

CHARACTERISTICS OF THE SOIL. 1 69

great is the influence of specific heat on the productiveness of
the soil. The action of water in reducing soil-temperatures is
easily explained. The physical condition of water is the direct
result of temperature ; with suf^cient variation in which it may
assume either a solid, liquid or gaseous form.

Evaporation of water, or its transformation into the form of
vapor, is due simply to the action of heat; the transformation is
performed at the expense of heat ; the more water evaporated
from the soil the more heat must be extracted from the soil
for the evaporation. Therefore, the more water contained in
a soil the lower must be its temperature because of the greater
evaporation and consequent exhaustion of heat. The amount
of hear required for this evaporation depends naturally on the
temperature of the water subjected to the action. Conse-
quently the soil-temperature in cold seasons or in cool climates
is much lower, proportionally, than the air-temperature, and
not seldom may fall actually below the latter. The experi-
ments of Park show that at a depth of 30 inches the difference
in temperature between soil wet and dry is immaterial, being
on the average for an entire year 6.25° C. and 6.62° C. respec-
tively, but the difTerence increased proportionally with ap-
proach to the surface ; at 13 inches the wet soil still remaining
at 6.25° C, while the dry-soil temperature stood at an average
of 9.75° C*

Schiiblcr, as the result of investigations made with twelve
different soils the temperatures of which were taken both wet
and dry, came to the conclusion that the average temperature
of the former was 38.15° C. and of the latter 44.88° C, or an
average difference of 6.73° C.

Somewhat different but more reliable are the more recent
results of the investigations of Stockbridge, whose trials em-
braced daily records for four months with both cultivated soil
and grass land identical except in the degree of moisture
present.f

* V. Gohren, Agriculturchemie , p. 97.

f Report Massachusetts Agricultural College Experiment Station, 1878.

170

A' OCA'S AND SOILS.

AVERAGE

TEMPERATURE AT

4 A.M.

Dry Ci'LTiVAiED
Soil.

Wet Cultivated
Soil.

Dry

Grassland.

Wet
Grassland.

Air.

Soil.

Air.

Soil.

Air.

Soil.

Air.

Soil.

August.. . .
September
October. . .
November

C.
14. 1

8.1

7-7

-4-9

months

c.

16.5

12.7

II. 4
I.

C.

13.2

2.

6.

-6.6

C.
16 6

8.
II.

1.4

C.

II. 2

6.8

6.1

-5-3

C.

17-3

14.6

12.7

1.9

C.

12.4

5.8

5-6

-4.9

C.
17-7
143
II. 7

3-

Aver, for :

io.4°C

9.2°C.

12. 6X.

I2.6°C.

From these observations it appears that no appreciable dif-
ference exists between the temperatures of grassland wet or
dry ; while, on the other hand, cultivated soils appear to be on
the average 1.2° C. warmer when dry than when wet ; the differ-
ence in the results of observation on the two kinds of soil be-
ing doubtless due to the action of growing vegetation.

Though the reduction of soil-temperatures through the pres-
ence of moisture is thus shown to be less than is usually
claimed by other investigators, these results are doubtless more
nearly correct for American conditions than are those of Euro-
pean observers.

The actual amount of heat taken from the soil by the evapo-
ration of its water a? estimated by Dickinson in Herts, England,
after eight years' observation with drained land, was equal to
the evaporation of 90,'?^ of all the water entering the soil, only
the remaining lofo penetrating to the depth of three feet. He
estimated that during the time of observation the total amount
of water thus evaporated was 2,600,000 lbs., requiring the ex-
penditure of heat equal to that produced by the combustion
of 75 tons of coal.

The usual claim, however, that this evaporation is the direct
result of the action of the absorbed heat of the .soil is obviously
erroneous ; the actual expense of soil-heat being in reality con-
siderably less than at first apparent from these misleading fig-
ures, inasmuch as the evaporation of siirface-\N2X&x must result
to a certain extent, not only from the action of atmospheric
heat, but moreover from heat-rays incapable of absorption by cer-
tain soils which can suffer no reduction of temperature thereby.

i'''^»;;,;«i^^ji^''i^;s<;?,;.,i-::V*i\5; :s-;>ue iihA;>;;^^>' -.^c ^•«-

Fig. i6.— Lysimeter. A. soil; B, thermometer for soil-temperature; C, thermometer for air-
temperature; D, maximum and minimum thermometer; E, rain-gauge; K, side of !y-,im-
eter, 3 feet deep; G, outlet-tube; H, percolaiionreceiver. {To face page 171.)

CHARACTERISTICS OF THE SOIL. 171

This fact of the evaporation of soil-waters before their pene-
tration of the deeper sub-soil is of interest not only as related
to soil-temperatures, but as disproving the once agricultural
bete noir of soil leaching, since we here have ocular proof that
but \oio of the soil-water descends even to a depth of 3 feet,
while many agricultural plants send roots to a far greater depth,
clover roots, for instance, penetrating often more than 6 feet be-
neath the surface.

Experience with the lysimeter here in Sapporo is of interest
in this connection. The instrument has now been in place one
year, and yet thus far not a drop of water has been obtained
from it, showing that none of the rainfall for the year has
penetrated 3 feet, but has all been either absorbed, or has evap-
orated from the surface.

The total amount of rainfall recorded here during the grow-
ing season of this interval, from May i to November i, 1887,
was 400.7 mm., equivalent to 1 5.76 inches. The lysimeter there-
fore received 142.628 gallons of water, equal to 426,840 gallons
per acre, all of which was available for the crop, and not a drop
of which carried soil-nutriment beyond the reach of any com-
mon crop.

In the light of these facts, established by observations in
Europe, America and Asia, drainage-waters are not only of
slight moment as compared with the total quantity of soil-so-
lution, but their action on, or relations to, actual soil-nutriment
is of comparatively slight significance.*

The Soil-conductivity of Heat is comparatively slight,
so that the sun's heat as influencing the atmosphere is but
slightly felt by the soil. The heat not only penetrates the soil
to but a short distance, but the changes of temperature as
affecting the air are of little import to the soil, its temperature
being far less variable, and but slightly modified by change
from day to night, or from summer to winter. The limit at
which diurnal changes of temperature are felt is between 2 and
3 feet, while in temperate climates the annual changes of sea-
son are without influence on soil-temperature at a depth of 70

* For composition of drainage waters, see Appendix.

172 f! OCA'S AND SOILS.

feet.* These conditions of conductivity vary of course to a
certain extent with the physical character and chemical com-
position of the soil. Rocks and minerals are all better con-
ductors of heat than is either water, air, or organic matter;
therefore, the more humus a soil contains, the more slowly does
it respond to the influences of solar heat ; likewise, the coarser
the soil, the better a conductor is it ; while the finer soil, en-
closing more non-conductive air, is slow in warming through
the influence of the sun's rays.

Though the soil is a much better conductor of heat than is
water, the latter is superior to air as a conductor ; as a result
moist soils, the interstices of which are partly filled with water,
are better conductors, and warm faster and deeper, than dry
soils in which air, in considerable quantities, is present.

The Radiation of Heat from the Soil, and the conse-
quent cooling propensity of the latter, are directly proportional to
the absorptive power of the soil. Two soils of like absorptive
power toward heat possess equal radiating power. It does not
follow, however, that soils most rapidly warmed are likewise
most rapidly cooled again. Because the sun's rays are of two
kinds, illuminating-rays and heating-rays, and substances ab-
sorbing or radiating one kind of ray may be inactive toward
the other. For instance, lampblack absorbs heat-rays of all de-
grees, while white lead absorbs all illuminating-ra)-s, but only
heat-rays of lOO^ C.

It therefore follows that a soil may be very passive toward
the sun's rays, but at night be very active in radiating non-
luminous heat-rays.

In general, however, the greater the heating capacity and
conductivity of a soil, the more readily and rapidly does it give
off its heat and become cooled, clay being the most slowly
affected and sand the most readily influenced.

The absorption and radiation of heat by the soil are modified
by numerous influences ; chiefly by the properties of the at-
mosphere and protective covering of various kinds, snow, vege-

* Approximately the average annual atmospheric temperature for the given
locality.

CHARACTERISTICS OF THE SOIL. 1 73

tation, and clouds, all of which act lik'c non-conducting cloth-
ing to moderate the intensity or rapidity of the sun's action,
and retard subsequent radiation of the heat absorbed.

The Formation of Dew is, however, by far the most im-
portant result attending the phenomena of the absorption and
radiation of heat by the soil.

And concerning the origin, method of formation, and office
of dew, a wholly new belief has been adopted during the last
decade, and has supplanted the previously accepted theory.'^

Dew is simply aqueous vapor condensed by contact with a
colder substance and deposited as drops of water on the sur-
face of the soil or on vegetation. The theory of formation
until recently universally accepted is that proposed by Dr.
Wells in 1814. It explained the origin as the result of the
contact of warm atmospheric vapor with the surface of the
colder earth, and a consequent condensation and deposition of
water which becomes absorbed by the soil, or drunk by the
thirsty plant thus furnished with a never-failing source of water
of atmospheric origin, by which the soil at night more than
regains the loss through evaporation during the day. Iden-
tity between the formation of dew and the deposition of water
on the surface of an ice-pitcher in a warm room was thus es-
tablished.

This identity remains unassailed, but the error in deduction
was one resulting from false premises. The old theory pre-
supposed the coldness of the soil and the warmth of the at-
mosphere: conditions the essential falsity of which are easily
demonstrated with the simplest thermometer on any summer
evening. The condensation must, of course, result from cooling.
The only question is as to the medium. Experiment shows
the soil at the place of dew-deposition to be invariably warmer
than the surrounding vapor-containing atmosphere. The soil,
or warmer surface, cannot condense the colder vapor. The
process is reversed, and the condensation is the result of con-
tact of warm soil-vapor with the colder overlying atmosphere.
The ice-pitcher explains the fact completely, but the relations

* Miiller, Pouillet, Pfaundler, Lehrbuch der P/iysik umi Meteorologie (1881).
Bd. II. p. 635.

1/4 A' OCA'S J. YD SOILS.

of the two factors are reversed ; the soil is the warm vapor-
furnishing material, and the night atmosphere becomes the
cold condensing medium.

This new theory is the conception of Prof. Levi Stockbridge;
and the ingenious and important experiments by which the
facts became conclusively demonstrated are of his devising, as
are most of the important deductions drawn from the premises.
The results of his labors were published as a report of the ex-
perimental work of the Massachusetts Agricultural College
Experiment Station for 1878 ; and were issued as a State pub-
lication among the "Senate Documents" for 1879, ^^^ after-
wards made public in pamphlet form.*

Notwithstanding the revolutionary character of the theory
advanced, the facts adduced in its support were so incontest-
ably supported by experiment so conclusive that it became im-
mediately accepted by many of the most eminent physicists of
America ; and was at once adopted by the leading specialists
of Europe, including Profs. Pfaundler and VVollny ; and was
supported by such scientific journals as Dcr NaturforscJicr ;
Forschungcn aufd. G.d. Agricul. PJiysik; Nature; and \\\q Jour-
nal of Science.

The investigations of the originator of the new theory have
been repeated by many investigators with identical results ;
and little has been added to the facts as represented by the
first advocate. The only similar investigations requiring note
are those of Aitken, recorded in the Transactions of the Royal
Society of Edinburgh for 1885, whose conclusions are identical
with those of Prof. Stockbridge, and were reached as the result of
independent experiment similar to those of the American in-
vestigator made seven years previously, but of which the
Scotch scientist was ignorant.f

The experiments conducted at Amherst, Mass. were of such
importance, both through their scientific value and practical
application, that they will be recorded" at length, as opposed
to the facts still currently accepted by many agriculturists.

* Investigations on Rainfall, Percolation and Evaporation of Water from the
Soil; Temperature of Soil and Air; Deposition of Dew on Soil and Plant. Bos-
ton, 1S79. Rand, Avery & Co.. printers to the State.

f Chambers' Joinnal, i8S6. p. 351.

CHAKACTERISTICS OF THE SOIL.

175

The language used is occasionally that of the originator of the
experiments described and the best qualified demonstrator of
the facts enunciated.*

The Difference between the Temperature of Soil
AND Air is the direct cause of the deposition of dew; the ori-
gin of the moisture being of necessity in the warmer substance,
from which it is with equal certainty condensed. The old the-
ory of dew-formation accepted as for granted that as the ice-
pitcher was cooler than the atmosphere, the temperature of
the soil on which a similar deposition of moisture occurred
must likewise be lower than that of the surrounding atmos-
phere. The experiments made to fix this identity were super-
ficial and of necessity led to erroneous generalization. One of
them was a comparison of the temperature of snow with that
of the atmosphere, and as the latter was frequently warmer than
the former it was concluded that dew was condensed from the
atmosphere by the soil, a supposed cooler body.f

The Exact Relation between Soil and Atmospheric
Temperatures was exhaustively studied by Prof. Stockbridge
with these results :

Month.

May

June

July

August. . .
September
October. . .
November

Daily Average.

Temperature of Air.

Day.

Night.

21.7

26.5

31-3
26.8
27.
17.6
8.2

12. 1

14.7

17. 1

13-7

9.6

4-7

2-5

Temperature of Soil.

Day.

17. 1

28.1
32.6
27.8
26.2
18.4
-5-8

Night.

By this table it is shown that the average temperature for
the entire season was for air 22.7° C. by day, and for the soil

* Having been conversant with these experiments during their progress, and
possessing opinions in the premises much the same as those of the investigator,
the author has, by special permission, occasionally resorted to the language of the
latter without quotation or other reference.

f Miiller, Pouillet, Pfaundler, I.e. H. p. 635.

176 ROCK'S AXD SOILS.

22.2° ; while at night the air av^erage was 9.6°, and for the soil

It therefore appears that so far from the night temperature
of the atmosphere being higher than that of the soil, the latter
is on the average of an entire season of daily record 3.9° warm-
er than the air. This being the case, no dew could possibly
have been deposited by the condensing action of the soil.

These temperatures were, however, recorded at the time
supposed to give the maximum and minimum diurnal temper-
atures, varying somewhat with the season but being approx-
imately 2 P.M. for day and 4 A.M. for night.

The results thus obtained were thought to possibly furnish
an incorrect criterion for the average difference between the
temperature of soil and air for the entire night. Observations
were therefore made every evening during the month of
June, at 10 o'clock P.M. The average of these observations
gave the temperature of the soil as 18°, and of the air as 14.5°.
The diiiference being 3.5°, against 3.9° as obtained for the en-
tire season by the first recorded experiment. Results very nearly
coinciding, rt;/^ ///r soil, again being sJioivn tJic xvarvicr at tJie time
of dezv-eieposition, could not have been the precipitating medium.

These observations having all been made in one locality and
with but one variety of soil, observations were next instituted
on thirty-four different kinds of soils, or soils under as many
different conditions, and all in different localities. The results
thus obtained showed the average night temperature of all the
various soils and numerous localities to be 18.9° C, and for
the air 16°, showing a difference of 2.9°. In no case was the soil
found to be colder than the surrounding atmosphere, and only
once was the air found as warm as the soil, and then in the mid-
dle of a dense wood on the night of a day on which the ther-
mometer indicated 38.9'^ at 2.30 P.M., in the shade, and the night
was remarkably sultry and still. Again, the soil, being zuarm,
was proved to be incapable of dew-precipitation.

The writer is here able to offer the results of observations of
his own, identical in nature and in result, but covering a very
extended area, with every variation of soil and of altitude be-
tween 300 feet and 9000 feet above sea-level.

CHARACTERISTICS OF THE SOIL.

177

Indeed, the thermometer and aneroid have been his almost
constant companions for several years, during which the rela-
tive temperatures of soil and air have been observed in Europe,
America and Asia with never a variation of the fact that tvlicn
and IV here dc%v is being deposited the atmosphere is invariably
colder than the surface on ivhieh the deposition is made.

One such series of observations only is oiTered in detail.

LOCALITV.

Frankfort

Heidelberg. . . .

Darmstadt

Odenwald

Waedenschye. .
Rigi Kulm. . . .

Interlaken

Lauterbrunnen.
Faulhorn

Scheideck

Rhone Glacier.

Lindeu

Innsbruck

Dolnach. Tyrol
Heiligenblut.. .

Salzberg

Munich

Soil.

Air.

13
15°
16'

15'

18°

14° C.

2° c.

3° C.

14° c.

10° c.

14° c.

9

14°
15°

12"

15°

Soil.

12° C.

1° C.
'6°"C.

' b" C.

10° c.

21° C.

19° c.

I'r'c.

14° c.
10° c.

10° c.

12° C.

21° C.

20° c.
14° c.

22° 'C.

20° c.

Air.

16°

c.

26°

c.

13'

c.

8"

c.

6°

c.

6°

c.

6°

c.

iq'

c.

21''

c.

11°

c.

2S°

c.

20°

c.

Elevation.

200

400
340
400
1,500
5.906
1.863
2,700
7,800
8.200
8.803
6,500
5,800
6.200
5,160
5.155
1,310
1. 812
3- 370
4,600
1.352
1.703
1.703

These observations were all made during the months of Au-
gust and September ; yet even at 2 P.M., the warmest time of
the day, only three localities out of twelve recorded show at-
mospheric temperature as high as that of the soil one inch be-
neath the surface. And if the temperature of the air is not
warmer than that of the soil during the time of the sun's great-
est intensity, it is of course impossible that the case should be
reversed after sun-down when the dew begins to form.

The record made at 6 A.M. with one exception was made
with soil wet with dew ; and this one exception was a morning
when vegetation v/as free from moisture, and is the only case
12

178

RCCKS AND SOILS.

where the soil was not found to be warmer than the overlying
air. The dew of these viornings and inimeroiis zvidely separated
localities xvas certainly not precipitated by a cold soil from a
ivarmer atmosphere, as such conditions did not exist.

The facts thus deduced were put to the test of observations
with soils under five different conditions and at two different
depths for a period of four months, with results as follows :*
AVERAGE TEMPERATURE AT 4 A. M.

Cultivated Soil.

Gr.^ssland.

F

OR EST

Month.

Dry.

Wet.

Dry.

Wet.

<

u
C/3t/3

s: .

— V

<

<u

1

1

18.8

13-4
12.3
3-9

12. 1

<

II. 2

6.8

6.1

-5-3

4-7

u rr

3 0
t/3t/3

17-3
14.6
12.7
1.9

II. 6

u

x: .
0 a

C 11
■- (U
uTO

19. 1
16.7
13.2

3.6

'3-1

<
12.4

5-8

5-6

-4-9

4-7

•iS
a'o

17.7
'4-3
II. 7

3-
II. 7

J3 .

^^

— u

19.2

15.9
12.7
4.8

131

<

14.1

10.2

7.6

-4.6

6-5

V

u
30

.6.7
12-5

4-4

12.2

V

C u

— 0

August

September

October

c.

14. 1

8.1

7-7

-4-9

I6.S
12.7

II. 4
I.

19.
14.4

12-5
2.

C.

13.2

2.

6.

-6.(

16.6

8.
11.

1-4

9.2

17-3
15.8
131

November

Av. for 4 months.

6.

10.4

II. 0

3-'

12.8

These observations were made in localities long distances
apart and under varying conditions of exposure and soil char-
acteristics, and are believed to show with accuracy the soil and
atmospheric temperatures of the region and period they cover.
The average night temperature of the air during the season of
observation was 5.1° C; the surface of dry cultivated soil
10.1° C, and at 5 inches depth 1 1.9° ; wet cultivated soil aver-
aged at the surface 9.2° C, and at 5 inches depth 12.1° C.

Dry grassland had an a\erage temperature of 11.6°, and at
5 inches depth 13.1°; wet grassland showed respectively 11.7°
and 13.1°; while forest land averaged 12.2° at the surface, and
12.8° at the lower depth.

The average night temperature of the soil at 5 inches depth,
for the entire period between August 1st and December ist,
was 12.6° C, or 7.5° higher than the nightly atmospheric tem-
perature for the .same period.

The result of all observations on the relative temperatures of
soil and air at night admit of but one conclusion ; namely, that
all soils on which dew is actually being deposited are on the

Report Mass. Agric'l Coll. Experiment Station, 1S78; pamphlet reprint, p. 15.

Fig. 17.— Illustrating Experiment No. i. A, dew formed on cover of box; B, soil free from

dew.

Fig. 18.— Experiment 2.

{To face page 179.)

CHARACTERISTICS OF THE SOIL. 1 79

average 3.7° warmer than the overlying air, and that therefore
the moisture precipitated is not the result of condensation by
the soil ; and that the latter cannot bear the same relation to
the atmospheric moisture that is borne by the ice-pitcher, and
that a new explanation of the phenomenon of dew-formation
must be sought.

If the soil as the condensing medium plays the part of the
ice-pitcher, the pitcher if filled with soil on which dew was being
deposited must inevitably become covered with its customary
beaded moisture.

The truth of this supposition was put to the test in

Experiment i. — A can of thin tin was prepared, which was
three inches square, five inches deep, and without top or bot-
tom. At eight o'clock of the evening of July 20th it was filled
with soil from a cultivated field, in the same manner as the
soil is taken into a lysimeter. It was placed on a grass-plot,
and there remained until the morning of the 21st, and, though
the surrounding grass was loaded with dew, there was not the
slightest trace of it on the box. At 4 A.M. of the 21st the
temperature of the soil in the box was 18.8° C; that of the air
was 15.5°. The experiment was repeated many times, with
identical results. The soil does not bear the same relation to
the air as the " ice-pitcher." On the night of July 25th a loose
cover was placed on the top of the box : on the succeeding
morning the top of this cover was dry ; but the under side,
next to the soil, was thickly studded with drops of water.

The principle illustrated by the " ice-pitcher" is a natural
one ; but it does not apply to the soil : in this case the soil be-
comes the warm, moist substance, performing the ofifice of the
air, and the air the cold substance, condensing its evaporating
water. If the soil of the field gathers water from the air at
night, then a given portion of it in natural position will be
heavier in the morning than at night ; if it evaporates water, it
will be lighter.

Experiment 2. — Two boxes were prepared with capacity of
a cubic foot. They were filled with soil in the same manner
that soil is taken into a lysimeter, and without disturbing its
particles or disarranging its strata. One was filled with absorb-
ent, retentive loam, the other with ocat : and these soils were

iSo

ROCKS AND SOILS.

taken because it was supposed that evaporation from them
would be less rapid than from gravel or sand. Tight bottoms
were nailed upon them, and they were placed in a trench in the
open field, level with the surrounding ground, and exposed to
all the vicissitudes of the weather. The experiment com-
menced the 1st of June, and was continued through the month,
except when interrupted by rain or fog, the boxes being
weighed night and morning. It will be noticed that the in-
crease and decrease of the weight was not uniform, which was
due to varying amounts of rainfall ; but the results were as
follows :

Loam.

Peat.

Evening

Morning

Loss !

Evening

Morning

Gain

Loss

Date.

Weight.

Weight.

1

Weight.

Weight.

lbs.

oz.

lbs.

oz.

oz.

oz.

lbs.

oz.

lbs.

oz.

02.

oz.

June I

1 10

4

no

I

0

3

112

0

in

8

0

4

2. . .

109

2

109

2

0

0 1

no

2

no

0

0

2

3

108

Q

108

8

0

I

108

12

108

12

0

0

4

108

0

108

0

0

0

107

b

107

7

I

0

5

107

I

106

15

0

2

105

I

105

2

I

0

6

106

6

106

5

0

I

103

13

103

10

0

3

7

105

14

105

II

0

3

102

5

102

I

0

4

9

"5

8

115

5

0

3

109

0

108

13

0

3

14

"5

12

115

Q

0

3 1

109

4

109

0

0

4

15.. .

114

q

114

8

0

I

107

9

107

8

0

I

17

"3

13

"3

13

0

0

106

9

106

7

0

2

19

112 j 4

112

2

0

2

104

4

104

2

0

2

20

109 4

109

3

0

I

103

14

103

12

0

2

21

no 6

no

b

0

0

101

13

lOI

12

0

I

23. ..

116 12

116

12

0

0

107 1 7

107

b

0

I

28....

115 1 15

"5

13

0

2

lof) j 14

106

14

0

0

29....

114 6

"4

4

0

2

105 1 2

105

I

0

I

This experiment, though not conclusive, indicates that the
soil at night evaporates water, and that it is possible that the
little moisture we find on the surface of a field in the morning
may have been received from deeper soil rather than rrom the
air. But the experiment was crude, the weights taken large,
and the danger of mistake in exact weighing imminent ; there-
fore the fact was sought by a different method.

Experiment 3. — A tin cup or can was prepared, 7 inches
in diameter and 8 inches high, and holding 308.67 cubic inches
of air. The sides were made doublt, h\it with the tin plates

,.,.,

Fig. 19.— Experiment 3. <(, double walled box (section); //, sponge for absorbing dew^.

''iirs»i»>j

Fig. 20. — Experiment 4.

■J. .-,,.

( To /ace pttge 181.)

CHARACTERISTICS OF THE SOIL.

l8l

an inc'i and a half apart to contain water to reduce the tem-
perature within the can to the same degree as the air
outside : it was without bottom, but had a top through which
was an orifice made tight by a cork, but in which was an aper-
ture to insert a thermometer. It was well soldered, so that
when it was put down upon, and its lower edge cut into, the
soil, it was practically air-tight. For the purpose of absorbing
moisture a piece of fine sponge was taken of twenty grains'
weight. The sponge was placed under the can on a wooden
peg two inches above the ground or board on which the cup
was alternately placed, and was weighed night and morning.
It was assumed that if the water absorbed by the sponge came
from the air, there would be a marked uniformity in the weight
of the sponge, whether the can stood on the board or the
ground ; but if it came from the soil, its weight would be
greatest when the board was removed. When the can stood
on the board, the outside air was excluded by banking around
the bottom with dry soil.

The following table exhibits the result of the trial :

Date.

Per cent

of

Humidity

of Air.

Inside
Tempera-
ture.

Outside
Tempera-
ture.

Cup on

Board,

Moisture

on Sponge

Cup on

Ground,

Moisture

on Sponge

Tempera-
ture of
soil.

Remarks.

grams.

grams.

f Rain on

June 7..

67

12.2" C.

11.1° C.

3.00

20.0''' C.

J previous
day; soil
[ wet.

9..

86

10.5

9.4

....

2-35

13-3

ID. .

92

10.5

9.4

3

10

II. I

12. .

88

10. 0

8.9

0.030

II. 6

13- •

88

14.4

II. 6

0.431

15-5

14..

72

II. I

10. 0

0.620

20.0

I5--
16..

83
62

14.4
14.4

14.4
15-0

0.550

1

76

IS. 3
18.3

17..

74

15-5

14.4

I

43

17-7

19..

70

II. I

10.0

0.245

17-7

20. .

88

15-0

14.4

2

76

21. 1

21. .

70

12.7

12.2

0.250

19.4

23- •

83

14.4

13-3

I

94

18.8

24..

87

15-0

15.0

4

50

18.8

25-.

87

12.2

13-8

0.740

16.6

{ Ground not
X hard after
rain.

28..

95

16.6

15-5

2.88

20.5

Ground just

29..

96

18.3

17-7

4.16

25.0

- hoed and
very moist.

1 82 ROCKS AND SOILS.

The rapidity of evaporation from any object is supposed to
depend on its temperature and the amount of water it contains,
modified by the motion of the air, its temperature, and its per
cent of humidity. But the table does not show by the amount
of water collected over the ground or board any special uni-
formity in this respect. It is noticeable that when the air
under the can was comparatively dry, as on the nights of the
l6th, 17th, 19th and 21st, the least water was collected; but
no attempt was made to ascertain if, during that time, its
humidity was increased by the soil-evaporation, or decreased
by sponge-absorption on the nights of the loth, 20th, 28th,
and 29th, when it had a high per cent of moisture and the
sponge contained the most water. It is quite possible, how-
ever, that, when the humidity of the air was near the point of
saturation, the sponge received all the water evaporated by the
soil, making its quantity large ; and, on the other hand, when
the air was dry, that received and held a portion of the evapo-
ration, making the sponge collection small. As a rule, the
amount of moisture taken by the sponge was largest after rain,
when the soil was wet, and at a high temperature. The result,
as a whole, corroborates the conclusions drawn from the second
experiment. The amount of water collected, though small,
must have been derived principally from soil-evaporation ; but
it does not determine what the maximum evaporation would be
if the soil had not been covered by the can ; for, as the enclosed
air approached saturation, the sponge would not fully relieve it,
and there must be a diminution in the soil-evaporation. There-
fore, the more completely to determine the whole truth, the in-
vestigations were continued in the following manner.

Experiment 4. — A double vessel of thin tin was prepared
which, within, would cover one square foot of soil and contain
half a cubic foot of air, and of the same holding-capacity in
the outside receptacle. On the inside, one inch above the
bottom edge, a gutter was soldered on the four sides, slightly
inclining to one point, and connected with a tube which passed
through the side of the vessel ; a tight fitting rubber hose was
drawn over this, and its outer end inserted in a flask. When
in use, the lower edge of the vessel was cut into the soil to the

CHARACTERISTICS OF THE SOIL.

185

depth of one inch, or as deep as the gutter would allow, to ex-
clude the external air, and the outside receptacle was filled
with ice and water to act as a condenser of the water vapor
within. The results of the use of the can on cultivated and
sod land, and on a board, were as follows :

Per cent

Actual

Actual
Water

ob-
tained.

Gain

Am"t of

Tern
pera-
ture
of the
Outside
Air.

Tem

of

Water

over that

water

pera-

Date.

Humidity

in

contained

ob-

ture

Remarks.

of Air

Air en-

in the Air

tained

of the

enclosed.

closed.

enclosed.

per acre

Soil.

Night of

grams.

grams.

grams.

barrels.

j

July 8...

82

01555

2-55°

2-3945

8.950

70°

75°

A leak at the tube.

9...

96

o-3°45

19.220

18.9155

70.941

76°

,,'\

Vessel on garden
soil recently hoed.

10. . .

95

0.2786

33.060

32-7814

122.216

76°

"•■1

Soil wet by heavy
rain previous day.

13...

92

0.2267

0.445

0.2183

0.818

70° J

74°

Vessel on a board.

IS--

82

0-I5SS

13.050

12.8945

48.364

68°

r

1

Vessel on dry sandy
land.

Vessel on grass-
land, and grass un-

16...

86

0.1684

17-430

17.2616

64-745

65°

72° \

[

der it, loaded with
dew, but little on
grass ouiside.

The water collected in this experiment was the evaporation
from a square foot of surface, and, though so small as to be
hardly appreciable for that area, yet in nature it is avast move-
ment, as can be seen by noticing the collection of the night of
July lOth, when it was at the rate of more than a hundred and
twenty-two barrels per acre. This may or may not be the
maximum of soil-evaporation at night ; but it conclusively
proves that the law of evaporation is not suspended or con-
travened, but is in active operation, at night, modified, of course,
in degree by those influences which affect it during the day.
The trend of the four separate investigations is clearly in one
direction, and teaches that in the open field, with soil and air
in natural condition, — the general soil, the upper stratum or
film of air-dry soil, — lifeless substances lying on the ground or
near it do not absorb water from the comparatively cold, dry
air, but obtain it directly from the water which is evaporated
by the warmer and more moist soil. On this principle, and
this alone, can the phenomena to which allusion has been made
be understood or explained, or that more striking natural
appearance commonly known as " ground-fog." This is seen
during the night, when there is no perceptible motion to the
air, as a compact sheet of mist of one. or two feet in thiclcr.e.s,.

1 84 A'OCR'S AND SOILS.

and resembling a covering of snow, and always over water or
very wet land. The surface-soil beneath the fog is many
degrees warmer than the air, and contains hundreds of times
more water in an equal space. Its abundance and warmth cause
rapid evaporation, which is immediately condensed and made
visible by the colder air. The principle which these observa-
tions appear to establish as governing the natural relations
which exist between the soil and water, in both the liquid and
vapor forms, and its movement thence to the air, may have a
more extended influence and application than has yet been
given it, and exhibit the cause and process of "dew-fall" in
the case of the living plant ; which phase of the subject should
here receive our careful examination.

Allusion has already been made to the principle of " dew-
fall " as illustrated by the " ice-pitcher ; " and dew is described
as " moisture from the atmosphere condensed by cool bodies
on their surface at night." With the principle and the fact as
stated, the belief appears to be and is in harmony, if no mis-
take is made in the application. It is, however, pertinent to
inquire if this heretofore universally-accepted and time-hon-
ored theory of dew-fall is consistent with many well-estab-
lished laws of plant-life and many well-known natural phenom-
ena. And, first, the plant is endowed with a most wonderful
and elaborate system of roots extending deep, far and wide
into the soil, which has a temperature at night many degrees
warmer than the air, and saturated with water of its own tem-
perature. The most important function of this root-system is
to gather soil-water, and force it upward, through every part of
the structure of the plant, to the leaves. This power is so
great, that when the plant is in rapid growth, and there is a
full water-supply in the soil, it is subjected to great pressure.
The root-force of plants has been frequently investigated, but
never more completely, or with a clearer or more decided record,
than by the experiments at the Massachusetts Agricultural
College in the years 1874 and 1875. It is recorded in those ex-
periments that the pressure exerted by a birch-root severed from
its connection with the tree was equal to a column of water
85 feet in height ; and that of a squash-plant eight weeks old,
suft, open in its texture, and very tender, exerted a force equal

CHARACTERISTICS OF THE SOIL. 1 85

to a column of water 45.5 feet high. Such plants as corn, to-
bacco, and the dahlia exhibited a similar power. The leaves,
acting in conjunction with the roots, pass nearly all the water
thus forced into their tissues, through their stomata, into the
air. A rapidly-growing calla in the college conservatory has
been noticed to exude water from its leaf-pores in such quan-
tity as to stand upon the s-urface or fall to the ground in large
drops. An Indian-corn plant, during its season of growth, has
been found to evaporate thirty-six times its own weight of water.
It has been stated, after careful investigation, that the leaves
on an average acre of forest exhale many thousand tons of
water during their summer growth, and a sun-flower-plant has
evaporated three pounds in twenty-four hours. There is no
natural reason why this evaporation should not be constant
during growth, modified only in quantity by the supply of
water in the soil, its temperature as affecting the activity of the
roots, the rapidity of the motion of the air, and by its content
of water. Second, young, succulent, rapidly-growing plants
standing in the field by the side of those nearly ripe and com-
paratively dry always exhibit much the most dew. Third,
other things being equal, those leaves and plants nearest to the
ground " collect " the most dew. Fourth, other things being
equal, plants growing on soils fully supplied with water show
more dew than those on dry land. The Colorado wheat-grower,
producing his crop by irrigation, determines when his lands are
dry, and need watering, not by examining the soil, but by
viewing the growing crop early in the morning. If this is well
covered with water, he knows the soil is moist ; if it has little
or none upon it, it is the reverse, and the irrigating-sluices are
at once opened. Fifth, some plants, at certain stages of their
existence, have dew upon them, if the direct rays of the
sun do not strike them, although it is several hours above
the horizon and the temperature several degrees above the
*' dew-point." These phenomena may not prove that plants
do not receive their dew from the air; but they give occasion
for serious doubts, and indicate the possibility that it may
come from the plant itself, or be a deposit of moisture rising
from the soil as in the case of the " ground-fog."

A consideration of the mutual relations of root-action and

1 86

ROCKS AND SOILS.

leaf-evaporation leads to the conviction that it is hardly possi-
ble that the force or the result is one of diurnal periods, as in
the case of the opening and closing of certain flowers, but
rather the cause is active day and night, unintermittcd during
the period of growth. But the positive fact could be proved
only by investigation, and was, therefore, attempted in the
following manner :

Do plants evaporate water at night ?

Experiment 5. — Two petunias and a cabbage-plant were
selected, of convenient size for the experiment, and in thrifty,
growing condition. A tin pot was prepared for each, in which
they were potted and soldered in. Tubes were inserted in the
top and bottom to admit water, and for drainage. The orifice
around the stem was closed perfectly with grafting-wax, and,
when on trial, the apertures for water and drainage were
stoppered with rubber-lined corks, so that it was impossible for
anything to escape from the pots except through the stem and
leaves of the plants. In this condition the plants, with their
pots, were weighed night and morning. The corks were
removed during the day, and the plants watered as their health
required. Fig. 21 represents one of these plants as potted for
use. Plants show no dew when kept at night in a sitting-room,
in a conservatory, or under a roof ; and to know if, during that
time, evaporation was taking place, one of the petunia-plants
was kept under cover, and weighed evening and morning, with
the following result :

Datb.

Evening
Weight.

grams.

Morning
Weight.

Loss.

Gain.

Remarks.

grams.

grams.

grams.

June 10. ..

240 . 040

238.260

1.78

0 s

(

Temp, of room, ii.6°C.
Humidity of Air, 88.

11. ..

231.050

229.850

1.20

0 j

Temp, of room, 12.7° C.
Humidity of Air, 70.

20. ..

224. 130

222.910

1.22

0

21. ..

233.065

231.855

I. 21

0

23...

229.5^5

228.335

1.26

0

24...

233 -^'35

232.445

I. 19

0

25...

230.575

229.145

1.43

0

26...

220.605

219.395

I. 21

0

28...

228.355

226.975

1.38

0

29. ..

214.75*5

213.325

1.46

0

30...

233.825

232.295

1-53

0

ClIARAC'I ERISTICS OF THE SOIL.

187

Though the result shows no regularity of loss in proportion
to the whole weight, yet the unvarying decrease proves conclu-
sively that one plant evaporated water at night, and indicates
clearly that this may be the law of all, whether situated in the
open air or in a room. But to prove or disprove this supposi
tion, one of the potted petunias and the cabbage plant were
nightly placed in the open air in the garden, with the pots
thoroughly wrapped in cloth to prevent their collecting water
from the soil, and with results as follows:
PETUNIA-PLANT.

Date.

Evening
Weiglit.

Morning
Weight.

Loss.

Gain.

Tempera-
ture of the
Air.

Per cent

of
Humidity.

Water
on the
Plant.

June 13

14

15

17

20

21

25

26

29

July 6

grams.

221.700
246. 800
252.900
242.880
148.060
169.125
167.905
165-305
158 955
158.395

grams.

218.370
246.550
251.460
242.160
148 240
169.165
167.605
165.105
158.925
158.155

grams.

3-33
0.25
0.44
0.76
0.00
0.00
0.30
0.20

0.43
0.24

grams.

0.00
0.00
0.00
0.00
0.14
0.35
0.00
0.00
0.00
0.00

degrees.

^2
60
61
62
64
61
56
57
72
S3

88
72
88

74
88
70
66

87
96

65

grams.

0.52

0.93
0.38
o.j6

CABBAGE-PLANT.

Date.

June 26

27
28
29

Evening
Weight.

grams.
234-685
259.005
250.720
238255

Morning
Weight.

grams.
232.725

254-775
250.S05

237.705

Tempera-

Per cent

Loss.

Gain.

ture of the

of

Air.

Humidity.

grams.

grams.

degrees.

1.96

0.00

57

87

4.23

0.00

63

91

0.00

0.85

64

93

0.55

0.00

'''

96

Water
on the
Plant.

grams.
T.80

2-77
4.87
4-15

CABBAGE-PLANT PLACED UNDER TIN CAN ON A BOARD, AND
THE TEMPERATURE REDUCED.

Date.

June 30

Ji^iy 5

6

Evening
Weight.

prams.

253-145
203.745
173-875

Morning
Weight.

grams.
24S.925
19S.955
173-405

Tempera-

Per cent

Loss.

Gain.

ture of the

of

Air.

Humidity.

grams.

grams.

degrees.

4.22

0.00

73

4-79

0.00

66

0.47

0.00

51

Water
on the
Plant.

grams.
1.32
o.go
0.47

1 88 ROCKS AND SOILS.

No attempt was made to determine the amount of water on
the plants as dew until the 25th, when, after the morning
weighing the leaves were wiped with a soft sponge as dry as
possible, and the plant re-weighed. It will be noticed that, on
nights when the plants lost weight materially, they at the same
time had dew upon them. This is explained by the fact that
frequently the plants stood in the garden several hours before
they gathered moisture ; at other times it commenced gather-
ing very soon after they were carried out. It may be that in
the former case the loss was occasioned by evaporation which
was not condensed. It was assumed that if the plants in the
morning, with the dew upon them, weighed more than at night,
it would be proof that the dew came from the general air, or
moisture arising immediately from the ground ; if they weighed
the same, or less, it must have exhaled from and accumulated
on the leaves. The result is not an absolute demonstration ;
but it furnishes the missing link in the chain of evidence which
will enable us to deduce conclusions having all the force of
principles ; and, that the evidence may be distinctly seen in its
proper relations, we recapitulate.

The declaration is made " that dezv on plants is water of vapor
of the air, ivhieh is deposited on eold objeets at nigJit, it being con-
densed thereby^ Proof : The exhibit of the " ice-pitcher."
Anszaer ist: The pitcher is at least twelve degrees colder than
the surrounding air. and on the outside hygroscopically much
drier ; and plants at night are, on the average, at least as warm
as the air, and therefore could not condense moisture. Anszaer
2d: The natural office of the leaves under force and pressure
of the roots is to exhale water into the air, and they do it at
niglit, nearly regardless of temperature. Anszver id : Some
plants exhibit dew in the day-time, if removed from the evapo-
rating influence of the direct rays of the sun, and when the
temperature of the air which surrounds them is many degrees
warmer than what is technically termed the " dew-point."
Anszver ^th : Plants abundantly supplied with, and containing
the largest per cent of water, and whose roots and leaves are
the most active, exhibit the most dew. Anszver ^tJi : In time
of severe drought plants have little dew, though there is a high

CHARACTERISTICS OF THE SOIL. 1 89

per cent of moisture in the air, and the nights are cold. Is it
probable, then, that living, growing plants are under the con-
trol of the law exhibited by the " ice-pitcher," or has a mistake
been made in the application of the principle ?

But, again: tlie declaration is made that dezv on plants is
caused by condensation, by the air, of warm vapor as it rises from
the soil, and wliicJi therefore collects on plant-leaves. Proofs — i st:
The vapor of the soil is much warmer at night than the air, and
would be condensed by it. 2d : Vapor from the soil is soon
diffused and equalized in the whole atmosphere, but is in laro-.
est proportion when evaporation is taking place near the sur-
face of the soil ; and, other things being equal, leaves and plants
near the earth have the most dew. 3d : Dew under boards,
hay-cocks, and like objects on the ground, could receive it from
no other source. Answers — ist: Admitting the facts, can they
annul or make inoperative the law of evaporation from the sur-
face of leaves at night, and its condensation there? 2d: Liv-
ing organisms in the performance of their functions are superior
to, supersede, and in a measure control, the laws of dead sub-
stance ; and the subject-matter of dew relates more specifically
to the living herbage of the fields. 3d : Water on the leaves of
a plant on a board under a can could not have been received
from the ground. The declaration is here made that dew is the
condensed exhalation of the plant. Proofs — i st : Plants evapo-
rate water at night. 2d : The air is colder than the plant and
its exhaled vapor, and would condense it at the surface. 3d :
The great preponderance of testimony is that, other things be-
ing equal, plants with the dew on them weigh less in the morn-
ing than on the previous evening, which could not be possible
if it was received from any foreign source. 4th : A plant con-
fined at night or during the day from the general air and the
ground will, if the temperature is reduced, have more dew upon
it after eight hours' seclusion than all the water in the air with
which it is confined.

Though of the greatest importance to the cultivation cf the
soil, the natural phenomena we have thus investigated are so
extremely subtle and delicate in their nature as to make abso-
lute demonstration a matter of the greatest difficulty. But the

I go IWCKS AND SOILS.

facts obtained harmonize quite perfectly with the known natu-
ral laws of the absorption, retention and radiation of heat by
different kinds of matter, and the movement and change of
form of liquid water in the soil and plant. They give a rational
and consistent explanation of many facts and phenomena which
ha\-e been enveloped in more or less of mystery, and may direct
to better or more intelligent methods in the treatment of soil
and crops.

Conditions modifying the Temperature of Soils are
of the greatest importance as of necessity modifying the rela-
tions between soil and plant. Vegetation must rank first
among natural modifiers of temperature conditions of the soil.
In summer the earth covered with vegetation is colder than
one offering free access to the sun's rays ; the result being in-
tensified by the relations between plant and soil water, and the
transpiration or evaporation of the latter by which means soil-
heat is necessarily reduced. In winter, on the contrary, the
vegetation-protected soil is much the warmer because of the
hindrance to heat-radiation offered by the covering of vegeta-
tion, turf possessing this property in a most marked degree,
and proved by Becquerel to be capable of ameliorating soil-
temperature as much as 5° C.

The relations of forest to soil temperatures have been ex-
haustively studied by Ebermeyer, whose observations show an
average difference, between the soil of forest and field, of 2,55°
for spring, 4.02° for summer, 1.55° C. for fall, while to the
depth of 1.3 m. both soils possess the same temperature during
the winter months. Forest soils naturally present least change
of temperature with differences of depth, and also slighter daily
modifications which seem to exert no influence below 0.6 of a
metre from the surface.

The Condition of the Atmosphere, as already explained
in considering the deposition of dew, exerts a modifying influ-
ence on soil-temperature, as the latter is modified by the
amount of radiation, which is greatest with a clear unobscured
atmosphere.

The Angle of Contact between Sun's Rays and Soil
Surface, naturally modifies the temperature of the latter; the

CHARACTERISTICS OF THE SOIL. I9I

more direct the contact, the more nearly perpendicular the
descent of the rays, or the nearer the approach to a right angle
formed by the earth's surface and the sun's ray, the warmer the
soil, because the greater the amount of heat received.

Consequently in north latitudes locations with a southern in-
clination, and in south latitudes with a northern inclination,
ma}' be many degrees warmer than localities of opposite aspect
or with surfaces more nearly level. Facts abundantly utilized
in the locating of vineyards and other crops requiring the max-
imum of sunshine for maturity or perfection.

II. The Soil and Electricity.

That the soil is a highly electrified body need not be re-
peated ; but the use or relation of this soil-electricity to the
production of plants is not so generally recognized. This elec-
tricity is largely, if not wholly, of frictional origin, resulting
chiefly from the friction of soil-particles, but also to a great ex-
tent from the friction between atmosphere and soil as the wind
moves over the surface. The atmospheric water entering the
soil as rain is also an important source of electricity. The ac-
tion of electricity on vegetation is doubtless of two kinds.
First, experiments made by Fischer directly establish the fact
that the electric current possesses the property of acting upon
the soil-constituents, rendering the insoluble ingredients more
soluble and, therefore, assimilable. Second, electricity is the
most active ozone-former in nature, acting on atmospheric oxy-
gen to convert it into the more active and energetic form of
ozone, the invigorating and vivifying effects of which on vegeta-
tion and animal life are witnessed with every recurring thunder-
shower.

III. The Relation between Soils and Gases.

Certain gaseous substances are, with comparative invariabil-
ity, present in most soils, not as an actual constituent part, but
as bodies external, of intimate connection, however, with the
various processes taking place in the soil, and thus properly
considered among properties of physical influence on soil-char-

192

Ji OCA'S AND SOILS.

acteristics. The gases thus demanding consideration are more
especially oxygen, carbonic acid, nitrogen, ammonia and vapor
of water.

These gases are present in the soil-interstices either as ingre-
dients of the atmosphere through which they have been dif-
fused, or are the result of decomposition, or of direct root-ex-
cretion.

The composition of the air confined in agricultural soils was
first investigated by Boussingault and Levy with these results :

Kind of Soil.

Cubic Feet

Air in i

Acre, to

Depth of

14 Inches.

Cubic Feet
Carbonic

Acid
per Acre.

c

omposition of this alr in
Volume pkr cent.

COj.

Oxygen.

Nitrogen.

4,416
3-53°
5,8gi
10.310
11,182
11,182
11,783
11,783
21,049

14
28
57
7'
86
172
257
1,144
712

19.66
19.61
19.99
19.02
18.80

'0-35
16.45

0
0

0

I

2

9

3

79
87
66

74
54
21

74

64

79-55
79.52

79-35
80.24
79.66

79.91
79.91

Clay soil

Unferiihzed soil

Asparagus bed fertilized

S.ind soil fertilized and wet

Sand 4 days later

Vegetable comport heap

Air 14 in. above i surface acre..

50,820

12

0 025

20.945

79 030

These results are chiefly valuable as having been obtained
with a considerable number of agricultural soils; and as having
been the first systematic efforts at investigating the composi-
tion of soil-air and its relations to the atmosphere and the
growth of plants.

But our knowledge of the composition and properties of soil-
gases has recently been largely increased, chiefly through the
labors of Fleck, Pettenkofer, Nichols and Fodor. The last-
named investigator, as the result of thirteen analyses, gives the
average composition of soil-air drawn from a depth of i
metre as follows :*

Maximum.

O 21.335

COs 0.899

22.234

Minimum.

Average

18.797

20.031

1.039

1. 019

19-836

21.050

* Bodcn und Wasscr ; und ihre Beziehungen zu den epidemischen Krankheiten.
Hygienischen Untersuchungen von Dr. Josef Fodor. Braunschweig;, 1882.
pp. (,c,-i42.

CHARACTERISTICS OF THE SOIL. 1 93
From 4 metres depth :

Maximum. Minimum. Average.

0 18532 17.290 17.906

COa 5.445 2.631 3.761

23.977 19.921 21.667

The differences between soil-air and the atmosphere were
demonstrated by subjecting the latter to analysis by the same
methods and with the same apparatus, resulting in an average de-
tection of 21.029 volume per cent of oxygen and 21.068^ CO^.

Through these observations the investigator arrives at the
conclusion that : "In the soil one of the constituents of the air,
oxygen, is in truth used, and then in its place commonly nearly
the same volume of CO^ is formed. In the soil therefore occurs
an oxidation of carbonaceous substances whose product is the
carbonic acid of the soil."

The relative proportions of the three chief soil-gases is found
to be exceedingly variable ; the oxygen and carbonic acid being
sometimes present in greater, sometimes in smaller, quantities
than this proportion in the atmosphere. A fact demonstrating
the activity of numerous processes in the soil more compli-
cated than the simple oxidation just noticed.

The varying proportion of oxygen and of carbonic acid is
doubtless due to the constant chemical decomposition and re-
combination. A part of the oxygen is utilized in the combus-
tion of organic hydrogen, part becomes combinec* with nitro-
genous matter during the process of nitrification, and still
another part combines with protoxides to form sesquioxides,
or to form oxides of lower combinations. And the carbonic
acid undergoes as many recombinations whereby its relative
proportion in the soil is constantly unstable ; as already re-
corded in considering the action of carbonic acid on soil-ingre-
dients.

Ammonia and nitrogen as existing in the soil have been
con.sidered under the composition of the soil. Water vapor
exists only in the upper soil-strata, seldom below a depth of 2
metres from the surface.

The relations between soil-gases and plant-nutrition are of
considerable moment and will be reviewed in Chapter IV.
13

194 ROCKS AND SOILS.

CHAPTER IV.
THE SOIL AS RELATED TO THE PRODUCTION OF PLANTS.

The soil was obviously designed for a special office in the
economy of nature, for the conduction of which the transfor-
mations and properties already considered are but the progres-
sive and systematic preparation necessary for the ultimate end.
This end or final office for the assumption of which so many
preliminary stages were passed is not other than the support-
ing of plants with which the earth is decked, on the presence
of which animal existence depends.

Though water and air are likewise each the habitat of a flora
peculiar to itself, the soil alone under normal conditions is the
home of plants of agricultural significance, and is, thus, alone
concerned in our consideration.

True, the soil is both home and nourisher of the plant-forms
occupying it. But neither as source of vegetable nutrition nor
as magazine or laboratory for the reception or preparation of
atmospheric matter for plant-nutrition does it occupy first place
in a consideration of the relations existing between soil and
plant. The office performed by the soil as bearer and habita-
tion of plants must be accorded position as of chief importance
in this connection, since all other properties must be subser-
vient to this on which alone their activity depends.

The Son. as Bearer and Habitation of Plants must
be considered as of first significance in governing or controlling
the other relations existing between the soil and the vegetable
product grown upon it. The influence thus exerted is of the
kind existing between all organic life and environment or
habitat, and thus controls or modifies not only individual and
race characteristics, but also development, health and maturity.

The ultimate amount of nutriment supplied the plant even
indirectly by the soil is but a fraction of the entire material en-
tering into its composition, and even this portion depends on

SOIL AS RELATED TO THE PRODUCTIOX OF PLAXTS. 1 95

no characteristic quality or action of the soil as an actual es-
sential to assimilation ; but it can, should circumstances allow,
derive this food directly from water solutions, without soil-
interposition, as is abundantly demonstrated by the numerous
experiments in water culture.*

The Soil is the Habitat of the Plant, the Place
OR Medium for Growth, a material furnishing the neces-
sary support or foothold for the roots which, penetrating the
mass, hold the plant in that position in which the life-functions
can be best performed.

The soil is, therefore, primarily simply the physical bearer
of the plant, and on the performance of this office all other
properties, and each other relation existing between them,
depend.

The function of the soil as the habitation of the plant is im-
portant and far-reaching; character, variety and perfection of
vegetable growth being dependent upon this condition of
habitat to a greater degree than to any other influencing factor,
with perhaps the single exception of character of climate.

Races of men and of most other animals are far more inde-
pendent of environment than is the case with vegetable forms ;
facts fully recognized on all sides. Animals are easily accli-
mated in any region to which they may be moved or compelled
to emigrate within certain limits of temperature.

Plants, on the contrary, however perfectly may be preserved
the climatic conditions of an artificial or new habitat, demand
certain physical and chemical conditions, in the absence of
which thrifty growth is impossible.

Though white birch and willow may grow in close proximity,
surrounded by the same atmosphere, bathed in the same sun-
light, and warmed to the same degree, no art of man can force
them to an interchange of habitat. Where the golden-rod
thrives, onl)- sickly violets can be made to bloom ; and no
farmer would attempt to grow cranberries and rye in the same
field. The question of habitat, then, or adaptability of crop to
soil, becomes a factor of the greatest moment, and occupies a

* Pfeffer, Planzenphysiologie (Leipzig, i88i), Bd. I. p. 70.

196 A'OCA'S AND SOILS.

most significant place in any system of culture. So universal
is the manifestation of this natural relation between soil and
plant, and dependence of plant on character of habitation, that
nature draws the most rigid lines of demarcation in field and
forest, and offers proof of the natural selection of habitat so
strong that the surest criterion for the determination of soil-
characteristics is furnished by the kind of vegetation with which
a soil is naturally covered.

The Soil as Feeder and Storehouse for the Plant,
and the relation thus maintained between them, follows natu-
rally the facts thus recorded, and on which this function of the
soil so directly depends.

All vegetation contains compounds of both organic and in-
organic matter, of which two classes of material plant-nutri-
ment must, therefore, consist. But whatever may be the na-
ture of the material entering into the composition of plants, or
to whichever division of matter it may belong, no vegetable
growth possesses the power of assimilating simple or ele-
mentary material, with the single exception of the element
oxygen. With this one exception, therefore, no elementary
body, however important a position it may hold in the plant
organism, can be considered as direct plant-food, or can under
any condition be, in a free state, assimilated by the plant, or
even assume the form of vegetable nutriment.

Only combined material is capable of furnishing the plant
with sustenance, and, hence, soil compounds alone bear any
direct relation to the growth of plants.

Of the compounds more or less generally entering into the
composition of plants, two groups, an atmospheric and a soil,
are recognized ; and of these the following are considered as
essential constituents of all vegetable forms :
I. Water, carbonic acid, ammonia.

II. Phosphoric acid, potash, soda, silica, lime, magnesia, iron
oxide, sulphuric acid, and hydrochloric acid.

Though other materials exist as constant constituents of in-
dividual plants or classes of vegetable growths, these two
groups of compounds are the invariable essentials of all vege-
tation. No agricultural plant grows without their presence

SOIL AS RELATED TO THE PRODUCTION OF PLANTS. 1 97

in sufficient quantity and soluble assimilable form in the habitat
wherein its life-functions are to be performed ; and in case
either sufficiency or assimilability fail, plant-life also fails.

The first of these two groups of substances, though wholly
inorganic in nature, is distinguished from the members of the
second group as consisting of products of organic decomposi-
tion or combustion, and existing in gaseous form as constitu-
ents of the atmosphere, and hence designated " atmospheric"
in contradistinction to organic and inorganic or mineral matter.
Though distinctly atmospheric in character, these three com-
pounds are unfailing constituents of the soil air, and enter the
plant-organism in solution through the root in a manner iden-
tical with that characteristic of mineral plant-food.

The second group consists wholly of mineral matter origi-
nally of rock origin. By the processes of combustion or of de-
composition these substances become separated from the or-
ganic bodies with w^hich they may have been combined ; and
are reduced to the form of solid, non-volatile ash or salts.

These facts render clear a circumstance not at first recog-
nized in considering the composition of plants or of vegetable
nutriment, namely, that though all living bodies consist of two
distinct classes of matter, organic and inorganic, combustible
and non-combustible, plants feed only on inorganic matter as
such, possessing the power of transforming inorganic matter,
carbonic acid, water, ammonia, nitric acid, into organic matter,
or combustible carbon compounds, by recombination, as the
result of the life-function of the vegetable organism.

As the inevitable result of this relation between these two
different classes of matter, their mutual dependence, each is
absolutely essential to the growth of the plant, one as neces-
sary as the other, and, without the presence of both in suffi-
ciency and assimilable form, plant-growth is impossible.
Growth is essentially the formation of new material, and the
new material of vegetable organisms consists of compounds of
organic and inorganic matter, only to be formed by recombina-
tion of the constituents of these groups of atmospheric and
ash materials. Hence, should either fail, the combination
must fail, and the formation of new material must cease.

igS KOCKS AND SOILS.

Neither atmospheric nutriment nor the soil-constituents can
alone exert any influence on the growth of plants. The at-
mospheric ingredients are the indispensable means for the
transformation of soil-material into organic compounds; and
the soil-constituents are, in like manner, the necessary means
by which is effected the change of atmospheric foods into
vegetable and animal organisms.*

The fact is also as incontrovertibly established that unless
each and every one of the members of these two nutritive
groups is accessible to the plant in suf^cient quantity and as-
similable form, thrifty development is impossible, and that the
absence of either of these constituents immediately manifests
itself in an abnormal development, or the death of the plant
thus deprived. Moreover, though other materials are often
essential ingredients of individual plants, and must exist in the
soils from which the plant feeds, and though other matter not
naturally a constituent of the given plant may be forced into
its organism by artificial conditions, the essential or normal
constituents of the plant must invariably and under all condi-
tions exist accessible to the plant, and for this material no sub-
stitute matter can be consumed, exchange of food-constituents
being wholly impossible.f

The inevitable result of these facts is the now established
truth that not one of the indispensable constituents of the
nutriment of a given plant possesses greater importance for
that plant than any other such ingredient ; for, without them
all, the action of each is impossible, and the absence of one
renders all the others ineffective as producers of normal or
healthy plant-growth.

* " Da weder die atmospharischen Nahrungsmittel fiir sich allein. noch die
Bodenbeslandlheile fiir sich allein auf die Entwickelung der Pflanze irgend
cine Wirkung aussern konnen, so sind die atmospharischen Nahrungsmittel die
unentbehrlichen Vermittler des Uebergangs der Bodenbestandtheile in organische
Verbindungen; und die Bodenbestandtheile die unentbehrlichen Vermittler des
Uebergangs der atmospharischen Nahrungsmittel in Korn und Fleisch." — Ueber
T/ieoric und Praxis in der Landwirt/iscka/t, von Justus von Liebig (Braunschweig,
1865).

f Rosenberg-Lipinsky, Praktische Ackerbau, Bd. I. p. 304- Breslau, 1879.

The experiments of Knop would nevertheless indicate that a slight substitu-
tion of soda for potash might be possible.

Fig. 21.— Potted plant used in Experiment 5-

Fig. 22. — Water-culture. Illustrating the necessity for a sufficiency of each plant constituent.
A grows in a perfect nutritive solution ; B in the same solution, except potash, which is
absent. (Pfeffer.) (To /ace page -i^t^.)

SOIL AS RELATED TO THE PRODUCTION OF PLANTS. I 99

The relations thus existing between the plant and the ma-
terials from which its organism is formed were first enunciated
by Liebig, who afifirms that " not one of the enumerated vege-
table nutrients possesses greater importance than any other ;
all arc equally indispensable to plant-growth^^

The Extraction and Assimilation of Plant-food.—
Having reviewed the nature and varieties of plant-food, it next
becomes necessary to follow the relations existing between
plant and soil a step farther, and inquire into the means
adopted by the plant for procuring the essentials to its growth
from the soil, and follow the stages of subsequent assimilation.

Though not an actual part of the subject of the relations be-
tween plant and soil, the life-history, growth and functions of
the plant form a series so complete and intimately related, that
before considering the fixed relations existing between plant
and soil, a glance at the fundamental facts of vegetable assimi-
lation of atmospheric foods seems necessary.

The Assimilation of Atmospheric Food by Plants in-
volves two distinct processes, inasmuch as these ingredients of
the plant enter its organism through two different and unlike
organs, the leaves and the roots. Oxygen and carbonic acid
are, however, the only constituents entering the plant through
the leaves ; all other food being absorbed by the roots from
solutions existing in the soil.

The Organic Ingredients of Vegetation are chiefly
the five compounds, starch, sugar, cellulose, fats, and albumin-
oids. The composition of the four first, or non-nitrogenous,
compounds, consists of some modification of combination of the
elements carbon, hydrogen, and oxygen, whence they derive
their designation " carbohydrates ;" while the albuminoid ma-
terial contains nitrogen as well. These materials all result from
the combination within the plant of the inorganic compounds
carbonic acid and water, with the addition of nitrogen in the
case of albuminoids, in which phosphorus and sulphur may
also be present in minute quantities.

The process of organic synthesis thus conducted by the plant

* Liebig, Ucber die Moderne Landwirthschaft (Leipzig, 1859), P- 24-

200

J^OCKS AND SOILS.

is briefly this : The carbonic acid of the atmosphere constantly
surrounds and bathes every part of the exposed plant. Com-
ing into contact with the green leaves, it enters the pores or
stomata with which the under surface of the leaf is covered.
Here, by the action of sunlight, a process of reduction follows,
resulting in the liberation of the oxygen of the decomposed
acid which passes out of the pores to again become mingled
with the atmosphere, thus purified, while the carbon remains
behind, and, combining with the water of the plant-circulation,
forms the carbohydrates of which the plant so largely consists.

Not only does sunlight prove to be indispensable to the
process of assimilation, but the green coloring matter of the
growing tissue, known as chlorophyl, is even requisite to the
transformation ; and is evidently the direct means for the com-
bination of the carbon extracted from the atmosphere with the
inorganic constituents of water.

The first and direct product of this combination is generally
starch, though possibly sugar may be the first actual product
of the union, remaining invisible, however, because of its solu-
bility in water or cell-juice ; and in certain plants, the onion
for instance, being the final product as well, starch remaining
wholly absent. Whichever of these carbohydrates, even
though it be fat,* may be the first and direct product of this
union of inorganic matter with atmospheric carbon, the entire
series may be formed by subsequent oxidation, whereby varia-
tions in the relative proportions of the three factors, carbon,
hydrogen, and oxygen^ are produced. f

The actual chemical transformation wrought may be ex-
pressed as follows :

Water.

Cellulose Oxygen.
or Gum.

Carbonic
Acid.

5H2O-4- 6CO2 = CoHioOs -fi20 liberated.

Starch

isHaO -f 18CO3 = (CbH, 005)3 + 36O liberated.

Glucose.

6H,0-|- 6COa = CHiaOe -fi20 liberated.

Sucrose.

iiHjO -|- 12CO2 = CijHaaOu -f- 24O liberated.

* Discredited by Pfeffer.

|- Pfeffer, loc. cit., Bd. I. pp. 182-21 1.

SOIL AS RELATED TO THE PRODUCTION OF PLANTS. 20I

Not only is it thus apparent that any one of these carbohy-
drate bodies is capable of construction by the union of carbon
with water, but the closeness of their relations one to the other
is graphically presented ; the difference between any two mem-
bers of the series being but slight, and transformation of one
compound of the group into another is readily effected.

It becomes evident, therefore, that from the starch resulting
from the assimilation of carbon, sugar, gum, oils, and cellulose,
the entire organic mass of the plant is produced as the result
of the life-function of the organism.

Moreover, though the conversion of starch into other carbo-
hydrates, for instance glucose, may be artificially accomplished,
the plant is endowed with powers not successfully imitated by
man, namely, the conversion of sugar into starch, cellulose, or
fats.

Not only is growth or the formation of new cells thus ac-
complished, but the plant elaborates material not required or
utilized as building material, but elaborates reserve material
deposited within the plant-cells. This reserved material is
destined as the prepared food of the plant when first begin-
ning the next season's growth. It may consist of any one of
the carbohydrate products of carbon assimilation, and be de-
posited in any part of the plant ; as starch in the potato-tubers,
sugar in the maple or beet, or oil in many seeds.

Having fixed the principles of carbohydrate formation, we
must next consider the remaining group of organic compounds,
and answer the question. How ARE THE AlbUiMINOIDS
FORMED?

Briefly, albuminaceous or protein nitrogenous plant-constit-
uents are the result of the action of nitric acid on non-nitrog-
enous compounds, probably sugar with the elimination of
carbonic acid and perhaps water, though direct combination
for albuminoid formation is not probable ; intermediate or ami-
do compounds being the direct product of the decomposition.
The definite method of combination still remains in doubt, and
is best summed up with the statement that " the synthesis of
organic nitrogenous substances within the plant is a function

202 KOCA'S AND SOILS.

of the living protoplasm in which material the entire process
occurs." *

Chlorophyll and light, however, seem inactive as agents of
protein formation. A singular property of the albuminoid
constituents of plants is the fact of their inability to penetrate
the cell-wall, and, therefore, move from the place in which they
were formed to the place in which their final office in the plant
is to be performed. For the accomplishment of this change
of position, the protein body becomes decomposed into aspar-
agine or some other amide compound, which penetrates the
cell-wall and enters the plant-circulation : a final change into
the ultimate protein body being again effected by the action
of carbohydrates, and the incorporation of the product with the
new cell-material, or its reservation as nutriment for the next
generation.

Though we have discussed only the assimilation of carbon
and exhalation of oxygen by the plant, as, by far, the chief life
process of vegetation, it must not be forgotten that the plant,
nevertheless, possesses to a limited degree the ability to absorb
oxygen, chiefly through the growing buds, and exhaling car-
bonic acid, particularly in the dark, thus actually completing
a process of respiration identical with that of animals, although
this must be considered as an exceptional rather than indis-
pensable life-process of the organism.

The Assimilation of Soil-food.

The extraction of nutriment from the soil and the assimila-
tion of this nutriment depend directly on the processes in-
volved in the utilizing of atmospheric constituents, since plant-
growth results only from the combination of the two for the
formation of new cell-matter. The office of actual absorption
of soil-matter devolves upon the mesh-work of roots penetrat-
ing the mass, and is accomplished through the cell-walls of the
root. And this food must exist in the form of solution, since
material only in this form is capable of entering the plant, and

* Pfeffer, L c. p. 245.

SOIL AS RELATED TO THE PRODUCTION OF PLANTS. 203

combininfj to become a constituent of its organism'. It is ap-
parent from this fact that but an infinitely small portion of the
soil-mass exists at any time in the form of actual plant-food,
or immediately assimilable material. The greater portion of
this plant-food is combined in comparatively insoluble form to
constitute the soil-mass itself.

The Methods of Solution, whereby the root is enabled
to procure material from the inorganic soil-constituents, have
already been reviewed in considering the subject of rock-disin-
tegration.

The process is nearly always the result of chemical action ;
the various acids which exist, or are formed, within the soil by
combination with different soil-elements transform insoluble,
or mineral, salts into more soluble compounds. But the solu-
bility of plant-food is not gauged by its susceptibility to water
action ; the carbonic acid, ammonia, and nitric acid present in
most soil-waters by combination directly influencing the solu-
bility of soil-constituents ; every other material dissolved in
the soil-waters being directly engaged in accomplishing the
same results.

Moreover, as already recorded (p. Ill), the root itself is Its
own best servant in dissolving mineral soil-matter, excreting,
or at least elaborating, an acid which, by direct contact with
mineral matter surrounding the root, dissolves the same, which
thus becomes, by the root's own action, directly assimilable
plant-food.

Not only does the root possess the property of dissolving its
own food from the intact rock-mass, but it is capable of seeking
out that nourishment demanded by its organism, and travelling
long distances, surmounting every obstacle in its indefatigable
search for the craved material. The distance thus traversed
by roots is frequently a radius greater than the height of the
plant itself; the direction of nearly all of the roots of many
plants being toward the most abundant source of required nu-
triment ; instances of roots extending long distances for the
sake of reaching and feeding on an accidental dung-dropping
are of constant occurrence. If a plant be grown on a soil made
up of strata of nutritious and non-nutritious material, the for-

204 ROCKS AND SOILS.

mer will be found filled with a mesh-work of rootlets, while
the latter remains nearly devoid of roots.*

Although the plant thus seeks the food essential to its growth,
it does not follow that it possesses the property of selecting
and absorbing only such material as is indispensable to its de-
velopment. On the contrary, the roots must take up whatever
is offered them in solution, even though, as is not seldom the
case, the material thus absorbed is injurious to the organism.
Plants no more possess the power of rejecting soluble mineral
matter, or of excreting non-essential material, than the animal
can reject a poisonous body present in its food ; essential and
non-essential alike enter the system if presented in a soluble or
digestible form.

Plant-development, however, by assimilation of nutriment is
subjected to the law of diffusion of fluids, or, better, the cell-wall
possesses osmose properties, as the result of which, although
the root takes up material in the proportions and relations in
which it is presented in the soil-waters, or nutritive solution, a
given constituent of the solution is drawn into the plant through
its roots only until the solution within the cell becomes satu-
rated with this one substance. That is, till the strength of
the solution is the fame on both sides of the cell-wall or osmose
membrane.

When, however, the mineral substance within the cell be-
comes assimilated, or becomes an integral part of the organism,
and, therefore, assumes insoluble form, the solution within the
cell becomes more dilute than that without, and the absorption
begins again to continue till equilibrium is once more gained.
It, therefore, appears that though the plant is endowed with no
power of selection of food, still the actual amount of material
and composition of the cell-fluids depend on the actual quantity
of soluble mineral matter used by the plant, and the character
of the same or essential nutriment varying with every family

* The power of roots to overcome obstacles in their search for nutriment was
forcibly illustrated by a large elm on the college farm at Amherst, the roots of
which travelled underneath a hard gravel road and filled a manured flower-bed fifty
feet beyond with such a mesh-work of rootlets that its cultivation was rendered
impossible.

SOIL AS RELATED TO THE PRODUCTIOX OF PLA.VTS. 205

of plants, each taking from the soil and assimilating food after
the demands of its own kind.*

In this manner it happens that different plants of varying
requirements growing side by side, on the same soil, and ex-
tending their roors into the same nutritive solution, derive un-
like materials from that nutriment, and develop systems of
widely varying composition.

But the plant, in its assimilation of nutriment from soil-solu-
tions, is not limited to supplying the actual demands, or posi-
tively essential materials, but often takes up substances in quan-
tities far in excess of the necessities of its existence. This fact
is naturally inferred from the statement that whatever mineral
matter was offered the root in solution entered into the circula-
tion of the plant. In case any element of plant-growth is pres-
ent in a given soil in predominating quantity, more of this
material, conditions of solubility being equal, enters into solu-
tion than of any other soil-constituent present, and quantities
in excess of the actual necessities for thrifty development are
taken into the plant-system, and become a constituent part of
the ash ingredients of its organism. f

The variations in the composition of the ash of most plants,
within certain limits, though each may have reached normal
development and attained an equal degree of thrift, are thus ac-
counted for. This superabundance of certain constituents has
led to the application of the term " nutritive luxuries " to these
mineral matters.

The Determination of the Charactkr and Quantity
OF Mineral Ingredients Indispensable to the Thrifty
Development of a given Plant is attended with no little
difficulty because of this variation in the composition of healthy,
normal plants of a given variety. Yet tireless experiment has
determined wath remarkable accuracy the indispensable con-
stituents of all agricultural plants.

Moreover, analysis of plant-ash demonstrates that the varia-
tion in mineral constituents oscillates only between certain

* Wildt, Katechismus der Agriculturchemie (Leipzig, 18S4), p. 62.
\ Johnson, *' How Crops Grow," p. 1S6.

206 /WCA'S AXD SOILS.

limits, beyond which in cither direction the variation cannot
pass, without resulting in symptoms of abnormal development.

Chemical analysis, therefore, offers a reasonably reliable crite-
rion for determining not only the nature but the quantity of
mineral matter required for the production of any definite
quantity of every known plant or crop. As the result of count-
less investigations, the fact has now become universally ac-
cepted, and adopted as a rule of practice, that average normal
agricultural soils contain suf^cient of all the inorganic constit-
uents of plant-food to withstand the depletion of constant
cropping for ages to come ; the gradual disintegration and re-
duction to soluble form keeping pace with the demands of
plant-growth — the elements potassium, phosphorus and nitro-
gen alone excepted. These indispensable constituents of all
vegetation must be supplied by artificial means, if the fertility
of the soil is to be maintained ; the quantity required being
obviously the same removed in the crop produced. This
amount is accurately determined by analysis ; and if the de-
mands of the crop are thus met, sterility tJirough dcficieney of
plant-food is impossible ; and if the material thus artificially
supplied to the soil is in excess of the immediate demands of
the crop, then increase in soil fertility or available nutriment
is the result.*

The Proper Concentration of Nutritive Solutions
IN the Soil naturally presents itself here for consideration ;
and the limits within which the most satisfactory results are to
be expected have been shown by repeated demonstration to
be capable of but slight variation.

The solubility of soil-matter is so slight under the most
favorable conditions in nature, that solution is accomplished
not only exceedingly slowly, but only with the action of re-
peated and large quantities of water. The results derived
from the researches of numerous investigators demonstrate
that the average concentration most favorable to plant-devel-
opment is I part of mineral matter per looo parts of water.
The maximum and minimum quantities of solid matters per

* See Appendix, tables of Ash Constituents of Plants.

SOIL AS RELATED TO THE PlWDUCTIOh^ OF PLANTS. 207

1000 parts of water beyond which deterioration in vegetable
product results were found by Nobbe to be respectively 2
and 0.5 parts.* These figures refer only to the entire or total
mineral content of the solution, the variation with individual
ingredients being far greater, and depending obviously upon
the relative proportion of each constituent demanded for the
normal development of any given plant. Indeed, since, as
already mentioned, all mineral matters presented to the root
in solution are of necessity taken up by diffusion, too dilute a
solution for utilization is impossible ; and the actual concen-
tration of many non-essential or occasional constituents of
plants as actually utilized by the plant must be almost incon-
ceivably dilute, I part of mineral matter to ioo,CK)0,000 parts
of water being not impossible as a matter of actual plant-as-
similation.

The amount of water positively acting on a given soil to fur-
nish the large amount of ash found in the plant from so ex-
tremely dilute a solution is far less than appears at first essen-
tial. The nutritive solution of proper strength, as presented
to the roots, loses a part of its dissolved mineral matter through
absorption by the plant, and the water thus set free acts again
on the soil to reduce new portions to solution. So that in
reality the same water may act again and again on the soil-
constituents, to reduce them to solution, and convey them to
the plant.

These facts of the concentration of nutritive soil-solutions
offer an explanation of an occasional occurrence in practice of
serious import to the production of crops, namely, the wilting
and possible death of plants through the application of plant-
food in a form too concentrated. This is particularly observed
in Japan, where human excrement is the almost exclusive arti-
ficial application to the soil ; and is elsewhere noticed through
the injudicious use of concentrated chemical fertilizers. In
either case the material is wholly and immediately soluble in

* Versnch Stat. vi. pp. 40 and 343, viii. p. 337 ; Johnson, " How Crops Feed,"
p. 320; Pfeffer, 1. c, Bd. I. p. 254,

208 J^ OCA'S AND SOILS.

soil-waters, and the resulting solution becomes so concentrated
as to prevent, or check, the process of water-diffusion in the
root. Th*; plant wilts, and if dilution of the solution does not
soon conne to the relief, and effect a renewal of the water-cir-
culation, loss of the crop must follow.

The Absorption of Nutritive Matter by the Soil is
a phenomenon of universal occurrence and widest significance,
as influencing the conditions of vegetable growth. Its mani-
festation is among the most common processes of nature ; yet
not till within the present half-century was it fully recognized
or appreciated in its bearings on plant-nutrition. Solutions of
either organic or inorganic matter are universally known to
lose a part of their solid constituents on passing through any
considerable quantity of soil. So great is this absorptive power,
and so well recognized is its efficacy, that wells are dug in close
proximity to foul waters with little fear of contamination ;*
and sand is often resortc d to as a filter for removing organic
impurities from potable waters.f

The nature or cause of this characteristic of the soil is clearly
of two kinds. First, as the result of physical action or surface-
attraction between particles. Second, and far more important
and far-reaching, is the exertion of chemical affinity between
soil-constituents and ingredients of the solution acted on,
whereby new combinations are the result, and a transfer of
acids and bases occurs between soil and solution.

Though every soil, even quartz-sand, is known to possess
this absorptive property in greater or less degree, the power is
limited, and ceases altogether in time, showing that saturation
occurs. This condition is naturally reached sooner with some
materials than with others ; hence the absorptive power of soils
is exceedingly variable, depending on composition of soil and
of solution acted upon, and consequent possibility of chemical
transformation and recombination.

* The author is not discussing hygiene, but soil-chemistry.

f The extent of this absorptive property is readily manifest by passing a solu-
tion of some organic coloring matter through a funnel of soil, when a colorless
liquid will be obtained.

SOIL AS RELATED TO THE PRODUCTION OF PLANTS. 209

The actual absorptive power of the soil for different nutri-
ents is evidenced by the experiment of Voelcker, who subjected
4COO parts of manure diluted with an equal weight of water to
the action of 300 parts of arable soil. The results shovv the
total absorption of different ingredients in i gallon (7000
grains) of solution.

Before mixing with earth. After mixing with earth.

Ammonia 19.68 grains. 6.91 grains.

Organic matter 184.05 " 11 8. 50

Silica 0.75 " 2.38

Phosphates of lime and iron 7.90 " 1.54 "

Calcium carbonate 17-46 " 79-72 "

Calcium sulphate 2.18 " 7.92 "

Carbonate of magnesia 12.83 " 6.16 "

Sodium chloride 22.85 " 18. go "

Potassium chloride 35-25 " 26.44 "

Potassium carbonate 85-27 " 4-29 "

338-22 " 282.76 "

It therefore appears that the soil experimented with ab-
sorbed 105.46 grains from i gallon of the solution ; equivalent
to 27.16,'^ of the total of solid matter present.

The results of the most recent and comprehensive investiga-
tions of soil-absorption may be summarized as follows : -

The nutrients ammonia, potash, soda, lime and magnesia
are absorbed ; while silica, phosphoric, hydrochloric, sulphuric
and nitric acids are not to any considerable degree absorbed.
The absorptive power as related to the nutrients potash, am-
monia and phosphoric acid is especially important inasmuch
as these supply the plant wath the three indispensable ele-
ments nitrogen, potassium and pho.sphorus ; and, moreover,
each of them is not only acted upon in a different way, but in
each case the cause of the action differs.

Phosphoric Acid becomes absorbed simply because it com-
bines with soil bases to form phosphates of alkaline earths and

* Complete reviews of the subject of soil-absorption, with the literature of the
subject, may be found in Knop's Die Boiiitirting d. Akererde (Leipzig, 1S72),
and in Mayer's Agricultur Chem., Bd. II. pp. 73-113.
14

210 ROCKS AXD SOILS.

metals ; compounds insoluble in water, and, therefore, not
taken from the soil by the percolating waters. Superphos-
phate applied to the soil as fertilizer soon combines with soil
bases to form calcium, magnesium, iron and aluminium phos-
phates. And in time the acid leaves its lime and magnesia
combinations, and unites wholly with the iron and alumina,
perfectly insoluble, and consequently totally absorbed or re-
tained by the soil. The carbonate constituents of the soil in-
crease phosphoric-acid absorption by transposition and conver-
sion into phosphates, chiefly of lime and magnesia, whereby
the acid becomes absorbed as a soil-constituent. Gypsum, in
like manner, gives up its lime for combination with the phos-
phoric acid, the sulphuric acid being set free. In each case,
the absorption is the result of definite chemical action.

Potassium, without doubt, passes from either the hydrate
or carbonate form directly into the soil as a component part of
the latter ; and although the strongest mineral acids exist in
most soils, their combination with potash seems a secondary
occurrence ; and Knop consequently ascribes to the soil a
" power of dissociation," resulting in the separation of bases
from acids, followed by new combinations. The maximum
quantity of potassium compounds appears to be absorbed in
the presence of hydrous silicates, with hydrated iron and alu-
minium oxides, amorphous silica, sand, and iron and alumi-
phosphates. On the other hand, little or no potash seems
absorbed by hydrous iron or alumina oxides when existing
alone, nor by the salts of the humus acids, and carbonates of
lime and magnesia.

AmmONI.\ combines with, or is absorbed by, phosphate of
magnesia, hydrated magnesia and iron oxides ; while the humus
acids unite with great readiness with ammonia, to hold it com-
bined in the soil.

It will thus be noticed that potassium and ammonia are acted
on by nearly the same factors, and become absorbed by approx-
imately identical soil-constituents.

The practical developments of the phenomena of soil-absorp-
tion as recorded by Knop are these :

SOIL AS RELATED TO THE PRODUCTION OF PLANTS. 211

Soils possessing absorptive powers from

o — I are wholly sterile ;

8 — lO are poor ;
1 5 are good ;
20 — 25 are fruitful;
50 — 100 are fertile.

The figures indicate the volume of nitrogen gas obtained
from the absorbed ammonia ; and some soils yield even a higher
ratio than here recorded, 135 being the proportion for Nile
mud.

The Absorption of Gases has already been mentioned
(pp. 191-193), where we found that the air of the soil varies
materially in composition from the atmospheric air ; a condition
due, in considerable extent, to the fact of condensation within
the soil. The amount of average condensation as determined
for different soils being as follows : *

Sand. Clay.

100 grammes of soil yield cubic centimetres of gas. . . . 29.4 32.2

The gas consists of —

Carbonic acid 16.5 26.4

Oxygen 15 13.3

Nitrogen 68.5 60.3

Ratio of o.xygen to nitrogen =: i : 4.61 : 4.5

The results here presented may be thus generalized : car-
bonic acid, though occasionally absent, is, as a rule, present in
large quantities in the absorbed gases. Oxygen exists in small
quantities, or is wholly absent. Nitrogen is absorbed in
greater proportion than it exists in the atmosphere, and in cer-
tain soils, particularly peat, is greatly condensed. Moisture
increases the ratio of nitrogen and oxygen in the absorbed
gases. Decomposing organic matter in the soil tends to reduce
carbonic acid to carbon monoxide. The carbonic-acid content
of the soil is increased by the presence of iron oxyhydrate ;
sunshine and elevation of temperature expel it ; consequently
the quantity present is greater at night than during the day.
Moisture tends to retain soil carbonic acid.

* Gohren, loc. cit. p. 117.

212 ROCKS AND SOILS.

Especially important among the phenomena of gas-absorption
is the fact that iron oxide exerts an absorptive influence upon
atmospheric ammonia, absorbing it in considerable quantities, as
evidenced by the following comparison of the absorptive prop-
erties of different soils toward atmospheric ammonia :

i.-:„^ ( c„.i Lbs. of Nitrogen in

Kind oi boil. f c

form of ammonia per acre.

Quartz and 5^ ulmin 46.041

Quartz and 3^ ulmin 24 . 300

Quartz and J% ulmin 7.00S

Ulmin 6.494

Iron oxide 12. 495

Carbonate of lime 3.286

Gypsum o . 295

Quartz 1.619

It therefore appears that the absorptive power of soils for
gases results not only in the retention of chemically active
agents in the soil, but in the actual absorption of plant-nutri-
ment from the air.

The Ultimate Results of the Absorptive Property
OF Soils as demonstrated by the facts reviewed are these :
The fixation is neither absolute nor lasting from any soil-solu-
tion ; a portion of the bases absorbed by the soil remains still
soluble in water, and enters into the soil-solutions, passing into
the drainage-water, or being utilized by the plant.

The composition of soil-waters is regulated or determined by
the absorptive property.

Essential constituents of plant-food are retained in the soil
in forms accessible to the plant.

Numerous important nutritive substances are converted into
comparatively insoluble, but chemically and mechanically ac-
cessible, forms.

The two least abundant and therefore most important mineral
ingredients of soils, potash and phosphoric acid, if set free from
rock-compounds, and entering the soil as phosphate of potash,
would, being soluble, be rapidly removed from the agricultural
soil by percolating waters, were they not recombined with
other soil-constituents, and fixed in forms available as plant-
food, yet not soluble in rain-waters and removed ; neither being
so soluble as to accumulate to the detriment of the plant.

SOIL AS RELATED TO THE PRODUCTION OF PLANTS. 213

It appears, therefore, that the soil not only contains ex-
haustless stores of most vegetable nutrients, but is, moreover,
endowed with a property which counteracts the wasting ten-
dencies of disintegration and nitrification, thus conserving its
own resources, and husbanding the soluble materials of artifi-
cial nutriment as permanent supplies of plant-food.

Soil-exhaustion.

The soil, consisting, as it does, of the elements of plant-
growth, however diverse and manifold may be the relations
existing between it and the plant grown upon it, is, so far as
the farmer is concerned, the raw material which it is the end
of his endeavor and labor to convert into either plant or animal
organisms. Husbandry is in reality, then, merely the hus-
banding of the soil resources, and converting them at least
expense into the most valuable ultimate or marketable form.
Could this end be continuously attained from soil-ingredients,
the acme of agricultural success is gained. The exhaustion of
the soil is, therefore, simply the exhaustion or loss of resources ;
and the prevention of this deterioration is the aim of all scien-
tific or intelligent agriculture.

Though the soil as consisting of plant-food may be disre-
garded, and may be considered as merely the receptacle of so
much fertilizer which as raw material is by natural force to be
converted into manufactured products or crops, agricultural
methods conducted on such principles are subjected to the dis-
advantage of neglect of the natural conditions or resources of
the soil ; and, therefore, fail of securing the desideratum of
agriculture, as of every industry, the most economical utiliza-
tion of the cheapest or naturally available materials.

Soil-exhaustion is, moreover, a relative term, being applica-
ble to a given soil for a certain crop, though a change of crops
would develop latent or unexhausted soil-resources, and an
available reserve of fertility ; a principle forming the basis of
all the numerous systems of rotation.

Thf-: Maintenance of Soil-fertility, though a most
intricate and involved subject as related to farm economy, is

214 ROCK'S AND SOILS.

fundamentally based on the simple fact already stated, that the
exhaustion process begins when the crop removes a greater
quantity of nutriment than is returned to it before the growth
of the succeeding crop begins. Maintenance of fertilit}' con-
tinues just so long as the annual depletion through plant-
growth is returned in available form.

Chemical analysis of the crop offers the most rational basis
for the maintenance of this fertility, by showing the actual
quantity of nutriment removed from the soil, and thus showing
the actual material necessarily returned to prevent deteriora-
tion.

The once much-lauded soil-analysis proposed by Liebig as
furnishing the data for successfully withstanding the effects of
cropping, and for maintaining the fertility, is no longer of even
theoretical value, offering the insurmountable difficulties of
constant variation in composition, and never showing the
ultimate available fertility present in any given soil.

In considering the needs of a given crop under any circum-
stances of growth, and the maintenance of the soil in a state of
fertility equal to the demands of the plant, the fact must be
constantly recalled that the fertility of the soil, its ability to
nourish and sustain plant-life, extends just so far as does the
minimum quantity of any food-essential present.

When the resources of the soil have been exhausted toward
any one ingredient of the crop, the ability of the soil to pro-
duce that crop is at an end; and further development of the
plant is impossible however abundant ma}' be the other
resources of the soil.

The plant can make no substance from nothing, or without
a sufficient supply of each and every one of all the essential
ingredients of its composition.

This fact applied in practice, and not only does the mainte-
nance of soil-fertility necessarily follow, but, as a natural and
'nevitable result, the cultivator is enriched by increase in soil-
productiveness, and the conversion of inert mineral matter and
free atmospheric material into organic matter endowed with
life, as the result of his husbanding of soil-resources.

USE OF THE SOIL. 2\$

CHAPTER V.
USE OF THE SOIL.

The foregoing chapters are devoted primarily to a consid-
eration of the properties of soils. Origin, composition, and
the various characteristics discussed are but the elaboration
essential to a presentation of the conditions influencing or con-
trolling soil-properties.

Knowledge of these principles leads to an increased facility
in their application and their more successful utilization.
Intelligent use of the soil is not only based on the action of
the laws involved, but is also the object of their consideration.

The use of the soil, therefore, involves the application of the
principles heretofore presented. Cultivation, or the produc-
tion of crops, is the use for which the soil was intended, and is
the natural subject of this chapter.

The special treatment of any particular crop or crops can-
not be attempted ; but cultivation in general, as a practice
based on theory, offers a natural and important field for con-
sideration.

Though the soil is the natural habitat or place of growth
for the plant, besides being the great storehouse for the elabo-
ration and conservation for plant-food, it is, more than all else,
from the practical standpoint of farm-management the invest-
ment or material to be utilized for the production of crops, or
raw material to be so utilized or manipulated by the cultivator
as to be most quickly and economically transformed into
finished products. In the care and management of this invest-
ment, as with any other, success is to be achieved only by
conserving, husbanding, and intelligently utilizing. All sys-
tems of rotation, fertilizing, fallowing, draining, or in other
way ameliorating soil-condition, are but systems for conserving

2l6 ROCKS AND SOILS.

the investment, means based on tlie laws involved in using
the soil to the best advantage by increasing or perpetuating
its productiveness.

Maximum production without diminishing future produc-
tiveness, the largest possible crops without exhaustion of soil-
fertility, is the object aimed at. The application of the prin-
ciples tending toward that end will now be considered, the
familiar processes followed in crop-production being discussed
in their relations to the scientific facts on which rational soil-
cultivation rests.

Preparing the Soil for the Crop.

If preparation of the soil is the first step toward crop-grow-
ing, the old adage is nowhere more applicable than here, for
certainly with soil well prepared for the crop efforts toward
production are "well begun," and thus more than "half done."
Irrespective of what crop may be contemplated, thorough prep-
aration is the first and most essential element toward success;
too much care or attention on this point is hardly possible,
and thorough pulverization is the prerequisite for proper
preparation.

Among implements of tillage the plow of course stands
first, both in importance and historical interest, and has been
appropriately accepted as the emblem of agriculture. The
degree of perfection in the plow is an unfailing indicator of the
condition of the agriculture of the locality or nation using it.

Strictly speaking, this implement is not a pulverizer, but
prepares the soil for the pulverizing to follow. The plow is
so devised as to utilize the principle of both the screw and the
wedge for lifting and inverting a strip of the surface-soil with-
out materially disturbing its particles. Not that the latter
condition is sought or desired, but the force exerted in sep-
arating the furrow-slice and inverting it necessarily results in
more or less compacting both it and the plow-pan underneath.
The degree to which this effect is produced depends naturally
on the ease with which the furrow is turned : the less the force

USE OF THE SOIL. 21/

necessarily exerted the greater the degree of pulverization
produced by turning the furrow ; and with soils already in a
mellow condition the plow itself becomes a real and effective
pulverizer.

For the reasons stated, and others to be considered, the
plow does not perform the duty frequently expected of it, and
certainly not all that has long been hoped for. So far as the
character of the work done is concerned, the spade is a far
more effective implement, though its slowness and cost of use
preclude recourse to the hand implement, and all attempts at
the production of a spading-machine as generally applicable as
the hand tool or the plow have been unsuccessful.

An inevitable result of the construction of the plow renders
its use on many soils conducive toward a condition eventually
serious. The pressure exerted in lifting the furrow-slice neces-
sarily impacts the bottom of the furrow. If nearly the same
depth of furrow is turned through several successive years, a
hard, nearly solid, and impervious " plow-pan " or stratum
results, frequently to the detriment of the crop. This hard
layer is not only sometimes impassable to roots, and the crop
is thus cut off from its supply of food and moisture, but the
hard stratum is so nearly impervious to moisture that excess
of rain is prevented from freely draining away, and the surface-
soil becomes so surcharged with moisture as to seriously injure
the crop. On the other hand, in times of drought, this same
impassable layer prevents the natural free movement of subter-
ranean waters to the surface by capillary action ; the surface
soil, above the interposed impeding layer, becomes dried
by evaporation and transpiration, and serious consequences
follow.

These conditions explain what have frequently been grave
puzzles in crop-puoduction. The remedy is self-suggesting.
By changing the depth of plowing, especially by a constant
though gradual deepening of the arable soil, the formation of
this "plow-pan " is prevented. If once formed, however, sub-
soiling by breaking the compact layer removes the difficulty.
The occasional exceptionally satisfactory results of subsoiling

2l8 ■ KOCKS AND SOILS.

are thus explained. The growing of root-crops tends toward
accomplishing the same result.

The pulverization is at best only begun witii the plow, and
must be continued with harrow, drag, roll, and other imple-
ments adapted to the soil and the particular crop to be giown
thereon. With any and all subsequent implements of tillage
there may occur a difificulty similar, though less in degree, to
that described a? to be guarded against with the plow. The
weight of the implement tends to press down and impact the
lower stratum while pulverizing the surface actually in contact
with the implement. So long as mere pulverization of the soil
is the end in view, this effect is doubtless occasionally injurious ;
but it probably is not infrequently without compensating re-
sults, inasmuch as a moderate solidification of the under stra-
tum facilitates the upward movement of soil-waters, while
thorough pulverizing of the very surface conserves the moist-
ure and retains accessible to the crop most of that finding its
way upwards.

This matter will be discussed more fully farther on.

There is no question but that all cultivated crops thrive in
proportion to the fineness of the soil on which they grow, so
that so far as mere crop-growth is concerned the degree of
pulverization can never be excessive. It is obvious, however,
that the increased productiveness of a given soil resulting from
its special degree of pulverization may not suffice to justify
the expense of the exceptional state of fineness attained.
There is therefore a practical limit beyond which artificial
pulverization of a given soil for any one crop may not reason-
ably extend. This point varies with every given field and the
particular crop to be grown thereon.

The object of pulverization must here be recalled. Though,
fundamentally, the soil is broken or the stubble turned that
the crop may be more readily introduced to the soil, still with-
out a certain degree of mellowness the crop, even could it
once gain a footing, would show but meagre and unsatisfactory
growth.

The reasons are chiefly two : First, the compactness of the

USE OF THE SOIL. 219

soil would admit of but slight root-development, and conse-
quently deficient food-absorption. Second, crop-production
being dependent on life-function, and all life dependent on air
or its essential oxygen, a compact soil, which is an jtnaerated
soil, is but imperfectly able to sustain life and its attendant
crop-growth.

This second condition is more far-reaching and important
than the first, because all food-formation or assimilation in the
soil is the result of, and depends on, chemical action, the prime
factors with which are atmospheric oxygen and soil-moisture.
All chemical action, or mere solution, \<> proportional to the sur-
face exposed to action. The finer the state of division of the
soil-particles the greater the surface exposed to action ; conse-
quently the greater the amount of air permeating the soil the
greater the quantity of water acting on it, the greater the
amount of plant-food prepared in the soil and the greater the
quantity actually assimilated by the plant, and the larger the
yield of crop.

The fineness of division here considered must be understood
as referring simply to the mellowness or separation of soil-par-
ticles and not to the fineness of, or size of, the individual par-
ticles themselves, which is a wholly different matter. There
seems to be a definite relation between soil-productiveness and
the fineness of the particles composing the soil-mass. Prof.
Whitney of Maryland has attempted to arrange soils into
definite types based on this fact, referring each type to the
crop to which practice shows it to be specially adapted. He
fixes the minimum and maximum degrees of fineness, or num-
ber of soil-particles per gram of soil, at one billion seven hun-
dred thousand and twenty-four billion grains or particles, re-
spectively, and designates these two soils as " pine-barrens ''
and " mountain pasture," referring to the typical natural prod-
ucts of the soils thus characterized.*

The gradations based on this principle of fineness or number
or particles per gram of soil would be as follows :

* Maryland Experiment Station Report, 1891.

220 ROCK'S AND SOILS.

1,700,000,000 grains, minimum fineness of agricultural soils ;

6,800,000,000 grains, sandy soils, garden-truck soils ;

8,000,000,000 grains, tobacco soils ;
10,000,000,000 grains, wheat soils;
24,000,000,000 grains, maximum fineness for agricultural soils.

The Supply of Plant-food is essentially part of the
process of preparing the soil for the crop it is to grow, and a
most important element in determining the results of the entire
undertaking, since without a sufficient supply of available
nutriment all other advantages must prove of little avail. The
food-requirements of a given soil depend almost entirely on
the particular crop to be grown thereon, since both soils and
crops vary so materially in composition, that a soil wholly de-
ficient in the requisites for the growth on a certain crop may
be abundantly supplied with the necessities for the production
of a different crop.

It must therefore be remembered that, strictly speaking,
soils have no food requirements, but the requirements of the
crop in question form the all-important problem on the solution
of which successful production chiefly depends.

Most soils are in a sufficiently fertile condition, that is, con-
tain a sufficient quantity of available plant-food, to render the
growth and maturity of a fair crop of any kind reasonably sure
under normal climatic conditions.

The fertilizer or plant-food question is therefore seldom
one of assuring productiveness, but rather of increasing pro-
ductiveness— the securing of larger crops 6n a given area. The
end may be achieved through two different means: either by
increasing the total quantity of available plant-food, or by cor-
recting the composition of the soil by changing the relative
proportions of food-ingredients required by the crop to be
grown, and thus securing a properly-balanced food-supply to
best meet the conditions of growtii for any given crop. Barn-
yard manure and complete chemical fertilizers are the best illus-
trations of the former procedure and the plowing under of
leguminous crops, supplying excess of nitrogen, and tiie appli-

USE OF THE SOIL. 221

t

cation of phosphates to make good the depletion in phosplioric
acid caused by successive grain-cropping, are common practices
illustrating the latter method.

The problem of maintaining or restoring soil fertility will be
considered later ; only the questions what and when plant-food
should be supplied to the soil as a step in its preparation for
the crop demand attention here.

Two elements enter into the rational solution of this ques-
tion— the crop to be grown and the soil which is to produce
the same. Only such principles as may be of general use will
be discussed, and the inter-relations between the wliat and the
when are so close that both considerations naturally unite to
form a single problem. For instance, if nitrate of soda, fur-
nishing nitrogen in soluble, easily elusive form, be thezt'//^/, the
time of application as near the time when actually required
by the growing crop is the when ; and if Fall application is the
when, nitrogen in comparatively insoluble form, tankage or
cotton-seed meal is the zvJiat. There are no sufificiently un-
varying data or facts on which application to all soils for all
crops may be based, nor even with invariable results for any
particular crop. These are, however, principles sufficiently
well established to offer basis for general practice. In this
matter the crop to be grown should be the controlling factor
rather than the soil on wiiich it is to be raised. /;/ the problem
of the rational application of plant- food the soil has received rela-
tively too much and the plant too little consideration.

We know the normal food-requirements of every agricul-
tural plant, while it is doubtful if a half-century of study has
yet positively determined the food-requirements of the Roth-
amstead soils for the most economical production of any
particular crop. Hoiv much less can any one claim to have estab-
lished the actual and invariable food-requirements or nutritive
idiosyncrasies of any other soil !

Soil-analysis is still clung to by some cultivators, and others
who should be better informed, as offering the longed-for miss-
ing knowledge. All other obstacles aside, however, the ina-
bility of the soil-analysis to show the amount or character of

222 KOCA'S AND SOILS.

the food-constituents of an}- soil except at the time the sample
is taken, and thus the kind and quantity of nutriment avail-
able to the plant during its entire period of growth, remain
hopelessly enigmatical.

For several years many of our experiment-stations, largely
under the instigation of the Department of Agriculture, have
been indulging in " soil-tests," "plat experiments," and "co-
operative experiments," with little actual benefit so far as the
enunciation of any law or principle furnishing reasonable basis
for a solution of the problem of rational fertilization, or even
means for definitely solving the problem for any particular
locality.

The fact still remains that the plant or crop to be grown on
a given soil furnishes the most satisfactory basis for settling
the question of the plant-food to be applied ; and scientific
workers as well as farmers are recognizing the significance of
the fact, and not only shaping their investigations but their
farm practice, also, in harmony with this principle.

The composition- and habits of groivth form the most nearly
fixed factors for determination of the food-requirements of
any given crop, and analysis of the crop in qiiestion, or rather
the average composition established by nunierous analyses, the
basis for rational fertilization. By this means the crop, being
supplied with the materials of which it is composed and in the
proportion found in the crop itself, must of necessity be pro-
vided with food-essentials required for its growth. True there
may be cases where one or more elements of fertility are pres-
ent in available form in excess of the requirements of a given
crop, and the artificial supply of such material as fertilizers
seems uncalled-for and wasteful ; still, if the food is supplied as
fertilizer it is not extracted from the reserve supply in the
soil, and thus soil-exhaustion is rendered impossible. On the
other hand, the moment the crop begins to draw upon the
elaborated food-supply of the soil in excess of the annual recu-
perative force of the soil itself or the additions of fertility arti-
ficially made, soil deterioration and exhaustion begin. A
material step forward in the predetermination of the fertilizing

USE OF THE SOIL. 223

requirements of crops and soils has been made in Helmkampfs
s. Ingestion.*

Plant-analysis is the basis of the method proposed, but
under new conditions. Crops grown with additions of the
different elements of fertility are subjected to analysis, and
these analyses compared with those of the same crop grown
without such treatment. If the proportion of any ingredient
in the plant is found to have been increased by the addition of
that ingredient to the soil, the fact is accepted as evidence of
the necessity for such artificial fertilizing. On the other hand,
whenever analysis shows no increase in any crop constituent
through the addition of such constituent to the soil, the crop-
requirements toward that element are satisfied, and its use
as fertilizer not required.

As a method for guidance in regular farm practice, however,
the average composition of the crop in question as established
by analyses, modified by the known habits of growth of the
crop to be grown, remain the most definite and satisfactory
basis for controlling the practice of fertilizer-supply. The
point of habits of growth and the modifying influence thus
exerted on the matter of food-supply as indicated by analysis
is best illustrated by the well-known relation existing between
leguminous plants and nitrogen-assimilation. Analysis shows
a certain amount of nitrogen present, and thus indicated as
required by a given crop; its Jiabit of growth, however, enables
it to extract much of this nitrogen from the atmosphere, and
the quantity required to be artificially supplied is therefore
reduced below the analytical quantity indicated. Of similar
importance is the fact that in normal soils the elaboration of
plant-food is a constant process; so that however low a state of
fertility or productiveness a soil may have reached, it is capa-
ble of supplying some plant-food, and thus growing some kind
of crop.

// is never necessary, therefore, to supply by application all
the fertility or food required by a7iy crop. The application

* Centralblatt fiir Agriculturchemie, 20, p. 826.

224 ROCKS AND SOILS.

should be based on the amount or degree of fertility possessed
by the soil; and the artificial supply be made in the proportion
that the available supply of fertility in the soil bears to the
amount of such material contained in a normal crop, or such a
crop as it is desired to produce.

To illustrate: If the soil has shown its capacity to produce,
unaided by fertilizers, one half of a normal crop, or such a crop
as is reasonably desired, the application of fertilizer should be in
the proportion the natural crop is to the desired crop, namely,
one half the material shown by analysis to be contained in the
normal crop, or quantity of crop desired, when unmodified by
peculiarities of growth, as already explained.

The tables in the Appendix, giving the quantities of fertiliz-
ing materials removed from the soil by all the different farm
crops, and the composition of the important American fertiliz-
ing materials, furnish the data, enabling any one to determine
these matters with scientific accuracy. It must not be forgot-
ten that in this discussion though the terms " composition "
and " ingredients " are used they refer to the essentials of fer-
tility known to require artificial replenishing in all normal
soils after continuous cropping, namely, nitrogen, potash, and
phosphoric acid.

The Form of Material in which Plant-food is sup-
plied is a matter of comparatively little importance, provided
only that it is, within reasonable limits, available ; that is, ac-
cessible to the crop when required. The important considera-
tion, after availability has been disposed of, in determining
the question of form of supply, is market value of the raw
material to furnish the nutriment required ; and locality will be
the controlling factor in determining this point. To illustrate :
In the Southern States cotton-seed meal will furnish a given
quantity of nitrogen cheaper than any other form of supply,
aiid for many crops equally available with other sources.

In this connection it is perhaps well to notice a prejudice
quite commonly prevalent against certain forms of food-sup-
ply as against others, this being particularly marked in the case
of phosphoric acid. Farmers naturally became familiar with

USE OF THE SOIL . 22$

bone as a source of this essential before other forms of supply
were known, and now commonly entertain the belief that
Thomas' slag and Carolina rock are only substitutes or even
adulterants of less actual plant-food value than the original
bone. Unquestionably raw bone or bone-meal furnishes insol-
uble phosphoric acid more readily converted into plant-food
than is the case with either other raw material. But all Caro-
lina phosphate and other mineral phosphates are sold on their
content of available phosphoric acid ; the greater part of all
manurial bone products are similarly placed on the market.
Available phosphoric acid is available irrespective of its source.
A given quantity or percentage of soluble or available plant-
food is equally valuable whether it was obtained from bones,
Carolina rock, Thomas' slag, or apatite.

The determining factor, therefore, in selecting a given food-
supply is not origin, but cost of the actual food contained
therein. To illustrate : Dissolved bone-black and dissolved
South Carolina rock-phosphate are two common forms of ma-
nurial phosphoric acid. The quality of the actual plant-food
furnished by the two forms is identical, yet at recent market
prices the available phosphoric acid in the bone-black cost 8
cents per pound, while the Carolina rock furnished the same
material at 6 cents per pound. What is true of phosphoric acid
is equally applicable to other plant-foods, particularly potash,
where the difference in market value between sulphate and
muriate is frequently great, even with the same proportions of
actual potash present, which for most crops is equally valuable
as plant-food irrespective of source.

The price per ton of fertilizing materials and the origin of
the same are no indication of the economy of purchase. TJie
cost per pound of the available plant-food known to be present
should be the basis for determining the real or relative value of
fertilizing materials.

Farm Manures are subject to the same principles applying
to chemical fertilizers, but with the very material practical dif-
ference that they are most commonly made on the farm where
used instead of being procured from an outside source. Stable

226 . J? OCA'S AND SOILS.

manure is the natural restorer of lost fertility, being the very-
material removed from the soil whose loss must be replaced if
deterioration is to be prevented. As such its production is the
corner-stone of all successful farming; and other sources of plant-
food are simply substitutes for manure, the production of which
should be fostered and increased by all the means at hand or
available. Modern farming, however, renders the sale of a
large part of the products of the farm without the intervention
of animal feeding imperative, and thus causes an inevitable loss
of fertility removed as crop, but not returned to the soil as
manure. Even when the crops grown on the farm are all fed
there and the manure so produced returned to the soil, the sale
of the animals themselves or their products necessarily removes
from the farm fertility not retained as manure; and to maintain
the soil without deterioration this abstracted material or lost
fertility must be returned in the form of plant-food obtained
from outside sources. The purchase of manure or fertilizers
direct, or the feeding of materials not produced on the farm,
but grown on some one else' soil, are the two most effective
methods for the maintenance of soil-fertility. Fallowing,
which is self-recuperation, and green manuring are also means
toward the same end, but will be considered elsewhere as not
directly related to the subject of preparation of the soil for the
crop.

After all rational means have been adopted, there is in our
farming, as a whole, an enormous discrepancy between farm
supply and farm demand for fertilizing materials. The ques-
tion of whence shall this demand be supplied is a vital one.
Two available solutions to the problem present themselves in
most communities, with relative merits varying with localities.
These are commercial fertilizers and y^\xxc\\-^%t^ stable or stock-
yard mayiurc. The latter could not begin to meet the demand
were it our sole source of supply of fertilizing materials. When
available, however, the extent to which it maybe economically
utilized in face of commercial-fertilizer competition is a most
important problem.

Plant-food is what we seek to replenish our soils. TJie cost

USE OF THE SOIL.

227

of the actual fertility obtained 7nust be the basis on which the
final selection should be made, though modifying conditions
will call for consideration.

In the manufacture of sugar saccharine matter is the sub-
stance sought. Siigar is sugar, and the refiner cares little
whether the beet or the cane elaborated his raw material. The
proportion of crystallizable sucrose or available sugar present
determines the economy of use. The farmer requires available
nitrogen, potash, and phosphoric acid. The proportion of avail-
able plant- food present in the raw material offered for selec-
tion should determine his action ; it matters little whether
stock-yard manure, cotton-seed meal, or a commercial fertilizer
chances to be the raw material used.

The following proportions and value of the actual elements
of fertility contained in the excrement of various farm animals
will furnish data for comparisons necessary to the solution of
this problem :

VALUE OF MANURE PRODUCED BY FARM ANIMALS.*

Food.

Amount

of manure

daily.

Value of Manure.

Animals.

Per ton.

Per animal,
daily.

Per 1000 lbs.
live weight,
value per yr.

Cows

Work-horses...

Sheep

Swine

i Hay, silage, )

< beets, bran, corn, ^

( cotton-seed meal )

Hay, oats

Grain, beets, hay

Corn-meal, flesh

81.5

52.5
7.2

3-5

$2.37

2.79
4.19
3.13

$0,093

0.073
0.015
0.006

$19.12

29.82
38.55
17.11

The value placed on the manure in the table is, of course,
estimated and not necessarily its actual value as plant-food.
This is, however, invariably the case with the so-called " com-
mercial values " given fertilizing materials. These trade values
of course vary somewhat with the condition of the market.
They are, however, definite, inasmuch as they show the actual
cost of the materials if purchased in the market. So in the
table the comparisons are accurate, and the different fertilizing

* Cornell Experiment Station Bulletin 27. These values make no allowance
for loss by waste.

228 ROCKS AND SOILS.

constituents of manures would have cost the amounts stated
had the same materials been purchased in the form of commer-
cial fertilizers instead of being furnished in the manures made.

Reference to the table shows that the average value of mixed
horse and cow manure, which may be taken as a fair basis for
comparison, is $2.58 per ton. The weight of manures made
and kept under different conditions varies far more widely even
than its composition, so that no standard can be satisfactorily
adopted. But the weight per cord or load of any manure in
question can be readily determined at any time, and this factor,
with the data in the above table, also by reference to the com-
plete tables in the Appendix, will enable any one interested to
determine for liimself the probable actual fertilizing value of
any particular lot of manure in question.

Facts, however, justify the assertion that it is extremely
doubtful economy to purchase common stable or yard manure
at its usual market price and then haul the same any consider-
able distance for application, when the actual plant-food con-
tained in the manure is the only reason for its use or value.
This statement, it must be borne in mind, is based on the com-
parative average cost of manure and of other fertilizing mate-
rials. The relative cost of plant-food in the form of manure
is still more enhanced by the materially greater expense for
handling and applying.

In this connection, however, a complete presentation of the
subject cannot fail to take cognizance of the fact that manure is
not always used solely for the actual fertility contained therein,
but that it possesses other features sometimes equally impor-
tant and desirable.

The Physical Action of Manure on the soil is not infre-
quently of vital importance ; indeed, on many soils its value is
chiefly the result of such action. The case is well stated as
follows :

" The value of barn-yard manure depends not so much upon
the actual amounts of the essential elements of plant food, since
analysis shows these to be comparatively small, as upon its
effect upon the physical qualities of the soil. It not only

USE OF 77/ E SOIL. 229

improves the mechanical conditions of both h'ght and heavy
soil, but it induces fermentative changes in the soil which
render available latent plant-food and promotes the capillary-
flow of soil-water toward the surface, thus augmenting both
tlie supply of water and plant-food."*

It is unquestionably the humus content of manure which
exerts this action, since humus is not only a powerful absorb-
ent of both water and gases, but its decomposition liberates
humic and ulmic acids, combining with insoluble soil constitu-
ents to make soluble ones. This absorptive power renders
dry soils more moist ; and the opposite effect is produced on
wet, heavy soils, which are made more light and porous by the
coarse, fibrous parts of the manure.

Admitting these properties of manure and giving them their
full importance, the question naturally arises: to how great an
extent does manure thus become indispensable ? A positive
and definite reply is impossible ; but it must be remembered
that these properties of manure are not peculiarities of manure
alone, but pertain to all animal and vegetable substances under-
going decomposition.

It is admitted by all that the actual plant-food contained in
manure does not render it an economical fertilizer when pur-
chased in competition with commercial fertilizers. Most soils
are sufificiently equipped with humus to keep the soil " in heart "
and withstand all legitimate drafts upon it for an indefinite
period under any rational system of care and cropping, even
though the drain on its resources be maintained by applications
of mineral fertilizers exclusively. This assertion will be more
readily accepted when it is recalled that humus is not itself
plant-food and is transformed into plant-food by nitrification
only very slowly, so that there is little drain on it as a feeder
for the crop. It must also be remembered that the very pro-
cess of crop production is necessarily a humus former, the roots
and other unremoved portions of the plants being important
sources of humification with some crops, clover particularly,

*Wisconsin Experiment Station Report, 1891, p. iii.

230 j; OCA'S AND SOILS.

the humus content of the soil being increased even by the
groivth and removal of the crop.

In addition to these considerations is the fact that a very
large proportion of our commercial fertilizers consist of or con-
tain ingredients little if any less important or potent as humus
formers than manure itself, ci)tton-seed meal, tankage, dried
blood, and fish pomace being good illustrations.

When it is further considered that most present systems of
rotation include the occasional plowing under of a green crop
equal in humifying action to a heavy dressing of manure, it must
be admitted that applications of manure need not be made
simply because of their humus content or action, and that the
same end can be attained whenever desired in conjunction
with a more economical source of actual plant-food.

This matter has been considered at length, because of the
prevalent belief among many farmers that though fertilizers are
cheaper than manure so far as the supply of fertility is con-
cerned, manure must be occasionally resorted to, even if neces-
sarily purchased at above its plant-food value, for its needed
physical action or humus supply required to keep the soil in
heart. Sand and clay soils are most in need of this action, and
with these manure is not indispensable to the highest success.
With other soils and rational cropping it is doubtful if humus
need ever be artificially looked after if the available supply of
fertility is maintained.

The Time and Method of applying Manures and Fer-
tilizers are of vital significance in their influence on results.

The character and composition of the material to be applied
must control the practice. Nitrogen is the ingredient offering
opportunity for error, especially in the time of applying, its
solubility and volatility in all manurial forms rendering it
extremely unstable. Manure as such is not available to the
crop ; it must first undergo decomposition that its fertilizing
constituents may become available. Decomposition, however,
is inevitably accompanied by loss ; this change should, whenever
possible, be made to occur in the soil after application, not in
the pile before. Reason and successful practice therefore

USE OF THE SOIL. 23 1

dictate that manure be applied to the soil as soon as possible
after being made, and incorporated with the soil as soon as
practicable, although certain experiments indicate that this
latter consideration is of minor importance.* When immediate
application is impossible, storage under cover and composlin'^
with muck, or sprinkling with plaster or kainit to prevent tlic
escape of ammonia, should be insisted on. Exclusion of air by
treading and moistening also aid in preventing waste. Super-
phosphate also acts like the other two preservers, its sulphuric
acid combining with the escaping ammonia to form non-volatile
sulphate of ammonia.

The loss in fertilizing value by allowing the manure to
remain unprotected in the common pile during the summer
frequently amounts to more than one half \\iQ actual plant-food
originally present. This fact must be remembered in connec-
tion with any estimation of the real value of the manure from
any animals based on the total manurial content of all the
excrement made.

Fertilizers of organic origin, animal or vegetable waste, may
be applied like manure with little fear of loss, even though the
total nitrogenous matter present be in excess of the immediate
requirements or assimilative power of the crop. Indeed some
such materials showing a high analytical content of nitrogen
are practically worthless as plant-food, the nitrogen being
present as combined nitrogen and not available, — leather, hair,
horn, and hoof-parings being good illustrations of such worth-
less materials, not infrequently incorporated with low-priced
fertilizers to give them an apparent value in excess of their
real worth, and incapable of positive detection by any method
of analysis.

Plants utilize nitrogen almost exclusively in the form of
nitric acid present as nitrates. Organic nitrogen first under-
goes decomposition, or putrefaction, resulting in ammonia for-
mation. This process is comparatively slow, and the ammonia
produced is either absorbed by the soil, "which has a wonder-

*New Hampshire Experiment Station Bulletin No. 6.

232 /BOCA'S AND SOILS.

fully retentive power for ammonia,"* or combined with
acids to form salts of ammonia. In either form ammonia is
rarely found in drainage-waters, but the loss is almost wholly
of nitrates.f

The nitric acid of these nitrates is the final product actually
utilized by the plant as food. It is formed by the process of
nitrification acting on tiie ammonia compound. + These facts
make it apparent that nitrogenous fertilizers applied to the soil
at such time or in such quantity that nitrogen formation is not
in excess of the immediate assimilative power of the crop is
practically free from the possibility of waste through leaching ;
and since nitrogen formation is practically at a standstill except
during warm weather, faJl, winter, or early spring, applications
of any nitrogenous manures except such as actually contain
nitrates may be made with impunity. Nitrates, of which
nitrate of soda (Chile saltpetre) is the only one commercially
important as a fertilizer, being already available as plant-food
without further transformation, and for which the soil possesses
little absorptive power,§ are removed from soils in drainage-
waters and lost to the crops if present in excess of their
immediate needs, and should not be applied in excess of
the actual requirements of the growing crop nor long before
the crop can utilize the same. The presence of vegetation
very greatly increases the retention of nitrates,! and the time
of most active growth is the period of greatest nitrogen assimi-
lation and least danger of loss. It is therefore well to make the
application of the total intended or required nitrogen at two
different times— one when the crop is put in, or in the spring,
and the other at the time of maximum growth of the crop in
question. The possibilities of loss of this most expensive
ingredient of all manures are thus reduced to the minimum.

The conditions here enumerated make one further fact

* Fream, Soils and their Properties, p. 69.

t Ann. Agron. 1890, No. 6, p. 250.

J See p. 127

§ Indiana Experinnent Station Bulletin 33.

1 Ann. Agron. 1. c.

USE OF THE SOIL. 233

apparent : When nitrates or ammonia salts readily converted
into nitrates, sulphate of ammonia being the chief commercial
illustration, are applied as fertilizers, most surplus of nitrogen
left in the soil in excess of that actually assimilated by the
crop during the growing season will pass into the drainage-
waters and become lost before the succeeding crop can utilize it,
except such as remains behind as combined nitrogen in the roots
and other crop residues. With many crops, however, this may
be a material addition to the nitrogenous content of the soil.

All soils should be fertilized " broadcast," irrespective of the
material used or the crop to be grown. Coarse manures should
be plowed under, fine ones and commercial fertilizers harrowed,
drilled, or cultivated in, the latter method being to all intents
a " broadcast " application in so far as the object is a thorough
incorporation of the fertilizer with all the surface-soil. Hill
and furrow manuring are obsolete, though for a quick start
small applications of manure or fertilizer may be made to the
drill, row, hill, or furrow in addition to the general fertilizing of
the entire soil of the field.

Amelioration of the Soil, when necessary, must of
course precede the application of plant-food for any particular
crop, but is, comparatively speaking, so seldom necessary as an
actual condition toward crop production that its later consid-
eration seems advisable. The actual reclamation of soils, that
is, the creation of arable soils from formations incapable of crop
production, should be considered as a distinct subject; and
drainage and irrigation, though frequently followed from choice
and betterment rather than absolute necessity, will be classed
under methods of reclaiming soils.

There are, however, other materials beside fertilizers produc-
ing chemical and physical effects on certain soils suflficiently
important to demand attention. Lime, chalk, marl, plaster,
sand and muck, are the materials resorted to for this purpose.
Lime, either caustic or air-slacked, decomposes the organic
matter in peat soils and converts combined nitrogen into am-
monia available as nutriment ; it also neutralizes the organic
acids often extremely injurious to vegetation. Chalk, marl,

234 ROCK'S AXD SOILS.

and plaster perform the latter office either directly or indirectly,
besides absorbing and fixing ammonia ; they also tend to lighten
heavy soils and render them more workable and productive.
Sand and muck each improves the physical condition of the
other, and also of clay. They are best used as stable absorb-
ents, and applied with the manure.

The Crop.

The selection and putting in of the crop necessarily depend
first on the market to be supplied, since it is useless to grow any
crop, however well adapted to its production the soil may be, if
the crop when produced cannot be disposed of at a profit.*

The relations between market and crop having been disposed
of, those between the soil and the crop demand consideration.

The chemical or nutritive conditions of the soil as related to
the crops to be grown are of little importance as compared to
physical characteristics, because the former, consisting simply
of the state of fertility of the soil or adequacy of available
plant-food, are easily controlled at will. Over the physi-
cal properties of the soil, however, its lightness, heaviness,
wetness, dryness, heat, or cold, the conditions determining nat-
ural plant habits and the adaptation of a crop to any given
soil are far less susceptible to modification or control. For
these reasons the chem.ical relations of different crops to cer-
tain soils may be passed lightly over. It must be borne in
mind, nevertheless, that every cultivated plant has its special
food requirements based on its own composition ; and these
natural relations between the composition of the soil and the
composition of the plant to grow thereon should be taken ad-
vantage of in the matter of determining crop adaptations
when ever possible, even though the maintenance of the
necessary relations between the materials existing in the soil
and those entering into the formation of the plant and derived

* Unless the indirect benefits from cultivation are equivalent to the cost of
the same.

USE OF THE SOIL. 235

from the soil may be artificially maintained by rational fertili-
zation.

The special adaptations of blue-grass to lime soils, of celery
to muck soils, and of rye to sand are illustrations of the rela-
tions existing between many plants and the composition of the
soils on which they thrive. Yet even with these crops the
typical physical characteristics of such soils are not without
bearing on their crop adaptations.

On the other hand, the proverbial preferences of cranberries
for peat, melons for sand, and cabbage for loam are evidences
of the intimac}' existing between crops and the physical char-
acter of the soils the}- prefer.

The Physical Properties of Soils as Affecting Crop
Adaptations demand special consideration, since, whatever
may be the relations between plant and composition of the
soil which produces it, crops possess but little ability to over-
come physical disadvantages; and the adaptation of soils to the
physical requirements of crops is one of the great problems of
modern agriculture, involving as it does the most vital matter
of controlling the relations between crop and moisture, and
heat.

The Relations between Crop and Moisture are un-
questionably the most important factors in controlling results,
and over which the farmer exercises least control. Indeed
over a large section of our country the problem of water-sup-
ply to meet the demands of the growing crop is the one obsta-
cle in the pathway of success. Most farmers would gladly take
all chances of frost, insects, disease, and poor markets could
they only be assured of an adequate but not excessive supply
of moisture during the growing season.

Modern methods of cultivation are increasing the independ-
ence of the cultivator on the sufficiency of natural moisture
through rainfall. The success of irrigation over large areas
where formerly deemed unfeasible is now subject for common
recognition, and requires no comment. Artesian irrigation,
however, is now receiving added attention, and success has
been sufficiently frequent to justif}' great expectations. In the

236 J? OCA'S AND SOILS.

great James River artesian basin of the Dakotas success in
securinfj abundant flow of water at depths from 150 to 1 500
feet, with an average of about 600 feet, has been almost invari-
able. The only question is the adaptability of the water to
irrigation purposes, there being wells flowing enormous quanti-
ties of water, so strongly saline, however, as to be unfitted for
application to crops.

In California, Colorado, and Utah artesian irrigation has
proved a success, and in Western Kansas the past season has
seen the introduction of secondary artesian irrigation, the water
being lifted from 130 to igo feet by windmills, and with every
promise of eventually reclaiming the drought-stricken portions
of the State. Tiie number of artesian wells now existing west
of the 97th meridian is 13,750, not all of which, however, are
or can be utilized for irrigation. The number of acres under
ditch in 1891 was 8,026,526.

Sub-irrigation, though possessing certain advantages, partic-
ularly in removing alkali from the so-culled " alkali soils " and
for greenhouse use instead of surface sprinkling, is too expensive
to justify general introduction for farm use.

Removal of surplus water is as essential in case of excessive
wetness as conservation of moisture is under reverse circum-
stances, but the details of drainage and its value are too well
known to demand detailed consideration here. CONSERVATION
OF Soil Waters is, however, of such moment and the princi-
ples involved still generally so little understood, that their
resume here seems appropriate.*

The investigations of Levi Stockbridge in 1878-9 have since
then been repeated and amplified by the experiment stations
of New York, Missouri, Storrs, Maryland, and Wisconsin, and
practically with only confirmatory results.

Soil-moisture is derived practically exclusively from the rain-
fall, and crops are incapable of absorption of water except by
root-action in the soil. The amount of soil-condensation of
atmospheric moisture, even when it can occur at all, is slight,

*See pp. 155-156.

USE OF THE SOIL. 237

estimated at one fortieth of an inch of water.* Yet soils by
evaporation and crops by transpiration are sending enormous
quantities of moisture upwards into the dry air constantly all
through the growing season. f

It is of importance in this connection to recall that poor soil
or imperfectly nourished plants require more moisture and
evaporate larger quantities than estimated as pertaining to
normal soils and crops, because of the more dilute solution,
smaller proportion of plant-food present in such waters, and
consequently a larger amount of water is required to convey a
given amount of food to the crop.;}:

Any and all methods for conserving this moisture during
periods of scarcity are therefore of the utmost importance on
every farm.

Mulching, or protecting the surface-soil by covering with
straw, grass, and similar materials, is a well-established practice,
particularly adapted to tree and garden culture, but incapable
of application to large farm proceedings. For cultivated-farm
crops, however, there is an effective method whereby soil-evap-
oration may be materially controlled, and hastened or retarded
as the necessities of the crop require. The movement of
waters within the soil is controlled by two forces — gravity and
surface-tension, and the passage is by means of capillary force
or through capillary tubes.§ Gravity exerts itself chiefly in
the downward passage of rain-water. Surface-tension is the
contractive power of the exposed surface, and does not depend
so much on the amount of surface as on the kind oi surface
acted on. Therefore the porosity or compactness of the soil
determined by the mechanical analysis of the soil, which shows
the number of soil-particles contained in a given weight of soil,
does not offer a definite basis for estimating the rate or relative
degree of water movement in the soil. Not the number of par-
ticles, but the arrangement of particles, determines the rapidity
of movement. Thus nearly impervious pottery-clay and a
good limestone subsoil may show identical results of mechani-

* New York Station Report, 188S, p. 196. f See pp. 159, 160.

X From " Soils of the Farm," p. 76. § See p. 162.

238 KOCA'S AND SOILS.

cal analysis — the same amount of cla}- and number of particles
per gram of soil, yet the latter would allow the passage of any
given quantity of water many times more rapidly than would
the former.'-'

The condition of the capillary tubes through which soil-
water passes, therefore, fixes the rapidity and amount of move-
ment. The conditions by which this end is to be attained to
the advantage of the farmer have been recorded ; now, how-
ever, the details of repeated experiment and widel}' distributed
farm-practice are available in support of the theory.f

It is an old and accepted principle, that tillage or soil cultiva-
tion has for its chief object the improvement of the physical
condition of the soil as related to the crop growing thereon ;
other advantages, such as increase in fertility through chemical
action, being but secondary. Among the physical conditions
of importance to the crop, those affecting the circulation of
water and food solutions are most important. The relations
between tillage and plant-growth are therefore most intimate.
The problem is, How can tillage be made to exert the most
benefit upon the growing plant ? On this point the evidence
of the past few years is conclusive.

Soil-waters are in constant motion. During rainfall the
water sinks by gravity, and if the amount of water supplied
is sufificient, penetrates to the permanent water-table, and
the entire soil is moist. When the rain ceases or the air be-
comes drier then soil-evaporation begins, the water rising by
capillarity. Certain crops, like corn and clover, are able to
draw a portion of the moisture required directly from the per-
manent supply or water-table.:}: Most crops, however, are
dependent entirely upon the water either falling on the surface
and taken up by the roots before it penetrates beyond their
reach, or on the supply brought up within available depth by
capillarity.

From the point of actual saturation or permanent water
upwards the soil is always moist; but at a certain height,

* Experimentstaiion Record, May, 1892, p. 668. f See pp. 161-2.

X Wisconsin Experiment Report, 18S9, p. 193.

USE OF THE SOIL. 239

except when the surface-soil is wet from recent rain, this moist-
ure disappears, and a dry stratum of soil exists. An important
question, bearing on this problem is, Why does this soil be-
come dry when there is permanent moisture at some point
beneath, in the porous soil? Rapid evaporation from the sur-
face, removing water more rapidly than the loss can be made
good by capillary action, is the reason ; but the lack of greater
capillary power adequate to maintain the supply and prevent
the surface from drying through excessive evaporation still
needs explanation.

The capillary tubes, as a result of this very evaporation, have
become partly dried, and therefore crumbled and broken, form-
ing wider tubes or more coarse structure of the surface-soil, and
water finds passage through the wide open spaces impossible ;
surface-tension or pulling-up power of the soil not being equal
to the task, evaporation gains on capillary action, more water
evaporates from the surface than can be drawn up through the
coarse soil, and the surface-soil dries out while the crop begins
to suffer for want of water.

How to obviate this condition is the practical issue. The
cause offers means for prevention. If the surface-soil be main-
tained in so fine a condition that the capillary tubes remain
active, water will pass upwards and the necessities of the crop
be supplied. To what extent and depth must the cultivation
be followed to attain the best results are the important con-
siderations.

The experiments of Prof. Levi Stockbridge in 1879 demon-
strated that surface-cultivation to a depth of 4 inches increased
the water-content of the soil to its maximum.* More recent
investigations in many localities have simply confirmed these
conclusions.

" The deeper the tillage up to the depth of four inchesthe
greater is the increase in water content." f

Recent investigations have shown that on clay-loam soil 143
lbs. of water per square foot of surface was gained to the soil

* See p. 161, f N. Y. Station Report, 1888, p. 186.

240 J^OCA'S AND SOILS.

by cultivation to a depth of four inches. This was indepen-
dent of the moisture brought up from below through increased
capillary action, but not evaporated ; the figures showing simply
the difference in evaporation between tilled and untillcd sur-
faces side by side.*

Although, therefore, four inches seems to be the maximum
depth of cultivation for conservation of moisture, there are two
practical considerations which may modify the procedure.

In case of very shallow ploughing for small grains on prairie
soils in windy localities, like the spring-wheat area of the North-
west, four inches of tillage to conserve soil-moisture would
turn the entire arrable soil into a dry mulch to retain moisture
in the unploughed depths when the crops do not feed. A safe
rule would be : cultivate not to exceed one half the depth of
the furrow turned, up to a maximum of four inches of cultiva-
tion for water-conservation.

It must also be considered that four inches of tilling with
the object of preventing evaporation may result in injury to
roots in excess of benefits from increase in water-supply ; the
rule under such circumstances should be, till to four inches
depth, or to the depth where serious root-laceration begins,
beyond which harm would follow.

Soils should be cultivated as soon after rain as possible, that
excessive evaporation through the compacted soil may be pre-
vented, there being danger otherwise that this rapid evapora-
tion may diminish the supply of available water below its
amount previous to the rainfall. The disk-harrow is the best
implement for drying soils when excess of surface-moisture is
objectionable.

The smoothing-harrow or spring-toothed cultivators, finely
pulverizing the entire surface-soil, are best adapted to prevent-
ing evaporation. Rolling the soil increases evaporation, but
tends to draw water from the lower strata. The surface-tem-
perature is increased by the same means from i° to 9° F. at
I to 3 inches depth, and germination is hastened. f

* Wisconsin Station Report, 1891, p. 105.

f Handbook of Experiment-Station Work, 1893, p. 323.

use of the soil. 24 1

The Chemical Conditions influencing Soil-waters
require little consideration. Composition necessarily exerts a
material influence on the water capacity of all soils, their hu-
mus content being the important factor from its marked ab-
sorptive power. This, taken in conjunction with extreme fine-
ness of soil-grains, produces the greatest known water-holding
power in soils, the Red River Valley loam of North Dakota
holding as high as 84^ of water. Certain chemical compounds
retard the capillary flow of soil-waters, while others, chief among
which stands sodium chloride (common salt) in dilute solutions,
materially increase the rapidity of the upward flow. This
fact seems to be thoroughly demonstrated and accepted, yet
its actual bearing on farm practice seems to have escaped
notice.

There is among many farmers a well-established belief in the
manurial value of salt, while both they and scientific investi-
gators occasionally meet with apparent beneficial results from
the use of salt or fertilizers like kainit, containing salt, or like
combinationsof Chili saltpetre and muriate of potash (NaNO, -|-
KCl) capable of salt-formation, wholly inexplicable on the
basis of actual manurial value through supply of available plant-
food furnished. Scientists when called upon to explain this dis-
crepanc}' between cause and effect have always resorted to two
favorite arguments, neither of which has satisfied them or their
interlocutors, but they have been accepted in lieu of better.

The hygroscopic property of salt has been used on the sup-
position of the " absorption of atmospheric moisture," and hold-
ing the same accessible to the plant. The well-known decom-
positions and recombinations taking place in presence of salt
have been resorted to as evidence of " chemical action " on soil-
constituents, and consequent increase in amount of available
plant-food. Both explanations are based on facts, but wholly
insufficient to explain occasionally observed conditions. The
beneficial results following applications of salt are usually
noticed either on dry soils or during times of drought. It
seems to be reasonable, therefore, that the effects are due to the
fact stated — the increased capillary viovenient in soil-ivaters con-
taining salt in small quantities. Salt by increasing capillary

242 ROCKS AND SOILS.

action increases the quantity of water accessible to the crop,
and in times of water scarcity this additional amount of water
is sufficient to account for the improved condition of the salt-
manured crop over that grown under the same conditions, ex-
cept for the salt furnished.

There seems no flaw in the hypothesis, which is capable of
being put to experimental demonstration. A rational deduc-
tion from the premises would be the use of material like kainit,
capable of furnishing plant-food, as well as the capillary water-
increasing action of salt.

Alkali Soils owe their characteristic properties so largely
to their relations toward water-supply, that a few words of con-
sideration seem called for.

These soils exist in localities in most States west of the Alle-
ghanies, there being instances of such occurrence in Ohio and
Indiana as typical as any in Wyoming or California. More
commonly, however, they exist in regions of limited rainfall or
of periodical rainfall, under which circumstances their mineral-
salt ingredients are brought to the surface by capillary action,
and these deposited by evaporation accumulate in the absence
of dissolving rain, leaving a bloom or incrustation on the surface
often crystalline and several inches in thickness. The deposit
is generally nearly white in color, and consists of mixtures of
sulphate, chloride, and carbonate of soda, the first named pre-
dominating, with potash and other alkaline salts. The Cali-
fornia alkali possesses the following composition :*

Sodium sulphate 82.96^

chloride 48

" carbonate 40

Magnesium sulphate 50

" carbonate 13

Calcium phospiiate 20

" sulphate 10

Iron and alumina oxide 30

Potassium sulphate 9.52

Silica 1.34

Organic matter and combined water 4.07

100.00
* California Station Report, i8qo, p. gy.

USE OF THE SOIL. 243

There is little abnormal in the composition of these salts;
they are much such as the water extraction of any fertile soil
would contain. In arid regions or where swamps have been re-
claimed, with lack of rainfall or lack of drainage the soluble salts
accumulate and excess renders plant-growth impossible. Be-
sides the white alkali, which is not corrosive, a black corrosive
alkali is occasionally met with, more serious in its effects.

Neutralization of the alkali by chemical means, reducing sur-
face-evaporation and consequent deposition, and supplement-
ing the deficient rainfall by artificial water-supply, are the
effective means for overcoming the difTficulty. Sulphate of
lime, gypsum (land plaster), is the most effective chemical neu-
tralizer, converting the black alkali into the comparatively
harmless white form, 500 lbs. to i ton per acre being the appli-
cation required.

The conservation of moisture-supply or increasing access of
water for overcoming the effects of alkali are identical with
those described for general farm practice. The object is to
keep the alkali in solution, or by excess of water wash the salts
out of the soil into the drainage.

The Influlnxe of Soil-moisture ox Soil-temperature
results from the simple fact that evaporation of water requires
heat, and if the water is in the soil the heat is taken from
the same source, and thus in the soil evaporation becomes a
cooling process and, other things being equal, a wet soil is
cooler than a dry one.* It therefore follows that crop-methods
tending to dry the soil at the same time warm it, lengthen its
growing season, increase its adaptation to warmth-needing
crops and hasten maturity. On the other hand, increasing the
supply of available moisture produces opposite results. The
dry mulch of fine soil resulting from surface cultivation trans-
mits less heat to the lower moist layer, and the latter thus re-
mains cooler as well as more moist. Cultivation, or pulveriz-
ing of the surface, therefore, acts in two ways. Since soils in
crop are subjected to loss of moisture both by evaporation and

*See pp. 169-71.

244 ROCKS AND SOILS.

by transpiration through the plant, the destruction of weed 5
acts directly on the questions of moisture and heat as well as
on the waste of plant-food. This exhaustion of moisture by
action of the crop and its influence on temperature are fre-
quently wrongly interpreted.

Soil covered by crop, other conditions being equal, is not
kept moist by the presence, or shading effect, of the crop, but is
drier and therefore warmer than the bare soil, independent of
the heat resulting from organic decomposition — a fact of no
little importance in practice. The interpretation is that the
presence of a covering of vegetation, growing or as mulch, ren-
ders the soil wetter and cooler, and important as furnishing
additional control over soil-temperatures.

The Effects of Cropping.

The mere production of crops under natural conditions 's
nature's way of increasing soil fertility, the death and decom-
position of the plant where it grew enriching the surface-
soil by addition of all the mineral food brought up from lower
depths and all the nutriment derived from the air. Farming is
not nature, however ; and removal of crops is necessarily an ex-
hausting process, the prevention of which or recuperation from
which are the chief aims of modern agiiculture.

The removal of the crop grown from the farm which pro-
duced it is the secret of the difificulty presented, and its magni-
tude is in proportion to the degree with which this practice is
followed. To illustrate : Selling milk produced from the crops
of the farm is the removal of the very basis of the soil itself, and
calls for large returns of fertilizers in addition to the manure
produced to maintain the fertility of the farm. Butter, however,
consisting so nearly entirely of organic matter, air materials,
carries little fertility away, and its sale will be followed with
slight exhaustive effects.

In like manner the removal of only the flour constituents of

wheat while the straw and bran remain as feed is comparatively

.!, harmless, while the selling of wheat to the miller and straw to the

USE OF THE SOIL. 245

paper-manufacturer can only result in soil-exhaustion unless
the removed material is restored in purchased plant-food.

The principles involved in the prevention of soil-exhaustion
are identical with those already discussed under other sub-
jects.*

SOIL-RENOVATION, or the restoring of lost fertility, how-
ever, offers a phase of the problem for further consideration.
Each plant possesses its individual food-requirements, removing
from the soil the materials required by its own nature ; and ex-
cept within very narrow limits man possesses no control over
the food-preferences of crops. Each assimilates the constituents
required for its special making up, and approximately no change
in food-kind can be effected by artificial means, however simi-
lar may be the material offered to the material sought. One
alkali cannot be replaced by another any more than ammonia
can be replaced by carbonic acid, though both may be of
organic origin. It therefore follows that a given crop always
removes certain constituents from the soil, and that if this loss
is not made good the soil may become deficient in certain ingre-
dients while yet rich in other food-materials essential to other
crops. Crop Rotation is based on this truth and its practice.
The following of a given crop by one of unlike food-require-
ments, like tobacco with wheat, in a regular system not only
tends to diminish the possibilities of soil-exhaustion,h\\t is prac-
tically a form of soil-renovation, since by it apparent unpro-
ductiveness may be turned into decided productiveness.

Renovation depends on restoring the soil to a state of fertil-
ity, but fertility is not solely accessibility of plant-food. The
physical condition of the soil, as for instance impaction, may
exert material influence on results, not, however, to the extent
claimed by Prof. Whitney, who affirms that " soil-exhaustion
is due to a change in the arrangement of the soil-grains,
changing the relation of the soil to moisture and heat." f

The plowing under of green crops is the simplest step

*See " Assimilation of Soil-food," " Soil-exhaustion," and "Supply of Plant-

fo,.<i."

f Experiment-siaiion Record, May, 1892, p. 666.

24^ ROCKS A AW SOILS.

toward renovation on many soils. Clover is by far the best
crop for the purpose, and if the first crop is cut, the second
still remains as green manure. Its use is particularly effec-
tive on clay and sand soils, where organic matter is particularly
required. It must be remembered that thou<^h the clover-plant
is deep rooted, and brings up considerable mineral matter from
the subsoil to enrich the surface, complete renovation without
addition of manurial food in some form is not possible. The
time required, moreover, and consequent loss of use of land and
resulting idle investment, will in case of valuable land make ap-
plications of purchased fertility expedient.

The bare fallow is now scarcely to be considered in this
connection. Other leguminous crops, like alfalfa, field peas,
and crimson clover, offer certain advantages, and rye and
buckwheat may be utilized when clover will not thrive. It
must not be forgotten that pulverization is itself a fertilizer,
and access of air a potent soil-renovator. Plowing and culti-
vation to excess is therefore impossible, and tillage is often not
only the secret of the maintenance of fertility, but of its res-
toration as well.

Soil Inoculation as a method of renovation or of increase
in crop growing power is attracting merited attention, and is.
likely to become a justifiable method in practice. Not only
are leguminous plants best adapted to purposes of green-
manuring, but every soil is capable of growing every legume,^
particularly clovers and lupines. Red clover is not a natural
prairie crop, and will not thrive on new prairie soil; even now
its cultivation is not a success on the prairies of the spring-
wheat region of the Northwest. Its habitat has moved west-
ward from Ohio at the rate of about six miles per year — a fact
indicative of the bacterial theory of adaptation, namely, that
its growth is only successful in the presence of certain micro-
organisms in the soil, the activity of which is evidenced by the
" nodules" appearing on the roots of legumes.*

It is through the action of these organisms, or the presence

* North Dakota Experiment Station Bulletin, September, 1894, p. 53.

USE OF THE SOIL. 247

of the nodules, that the nitrifying action of the clover is be-
heved to be due. It has therefore been supposed that soils
incapable of growing clover could be inoculated with the germs
by being sown with soil from clover-fields containing the bac-
teria and nodules. Success has attended the attempt in many
instances, and the field opened offers promise of practical
utility.* In this same connection it is well to note the proba-
bility of the action of similar organisms on rock-disintegration,
and therefore on soil-minerals, and the conversion of the same
into available plant-food.

Renovation by Fertilization possesses no features dif-
fering from the principles applying to the fertilizing of special
crops. It must be clearly understood that however depleted
in fertility a soil may have become, if deficiency in available
food for the requirements of the crop is its only lack, supplying
of food adequate to the growth of the crop desired is effective
renovation. The crop-producing power of any soil is limited to
its ability to supply ail'oi the constituents required by the plant,
and the productiveness extends only to the limit of the smallest
required constituent of the crop. In building a brick building
it matters little how many brick may be available if the mortar
runs short, for then the construction must cease. In plant
building it avails little how abundant all other constituents may
be if one is lacking, for then crop-formation ceases or an abnormal
crop is the result. Should one or more mineral constituents
fail, then nitrogen is present in excess and the abnormal crop
is evidenced by its inability to stand alone.

Therefore, in practice it does not suffice that "phosphate"
be liberally applied, and thus be present in abundance, if
potash falls short of the requirements of a good crop. The
crop will consume the potash and other ingredients in propor-
tion, and go no further. If by any means it is known that
any single element of fertility is present in sufficient quantity
to meet the requirements of the crop to be grown, this con-
stituent may be proportionally reduced in the applications

* Experiment Station Record, February, 1892, p. 491.

248 ROCA'S AXD SOILS.

made. For instance, on swamp-lands sown to onions nitrogen
may be largely omitted in fertilizing applications for a time.

Where, however, as is the rule in practice, this knowledge
is not available, but one safeguard exists. Apply the three
elements of fertility shown by analysis to enter into the com-
position of the crop intended in tht proportion foimd in the crop,
modified by known habits of growth of the plant in question,
or manure witJi the equivalent of the crops removed.

Such rational treatment will prevent soil-exhaustion, or in-
sure restoration of crop-producing power.

APPENDIX.

250

APPENDIX.

PHYSICAL AND CHEMICAL PERCENTAGE

•a

c

1- c
n rt
3 <n

a

0

IT

si

.2 —

OJ (A

■a <«
c 0

nl u

D >

J= 0

^ " .

S S 9
0 « «

0

The

num

bers r

efer

I. IS

to

the

grade

s

5.20

deterrai

ned b

y mea

nsofthe

33 10

Noeb

els A

ppara

tus.

56.34
4.12
0.09

100.

C.70

r .20

1.50

0.78

0.84

1.38

1.80

' -^4

0 50

O.JQ

3.09

2.04

'•52

3-47

0.93

2. to

2.40

0.16

1.24

1. 41

1-35

C.05

0.40

O.IO

29.94

0.13

0.62

0.69

92.18

95-30

79.90

S7-00

89.15

91-35

82.17

6.26

3-50

16.40

12. O5
<=.4i-

8.59
0.49

7.21

14.6

\ J-5'

0.80

3.60

0-75
(

0.82

3-08,

.

0.89J

Physical Analysis No.*

CaCO, and MgCO,.

Loss by
Ignition.

Hydroscopic Water..

Combined Water

Humus

MgCOsCaCOa

Silica

FejOsAlaOs

Lime

Magnesia

Soda

Potash

1 . 12

80.63
15.42
0.14
0.23

0-4S
2.01

Apscrption of the
31 36 46
• See Physical

COMPOSITION OF AGRICULTURAL PRODUCTS.

2U

COMPOSITION OF TWENTY DIFFERENT SOILS.

!

O

C
£ 0

0

■T. U

1^

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55

Best wheat
and clover
soil.

is

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eg

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c

c

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1.27
2.03

0.27
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2.98

1.8s

407

3-57
76.23
15.66

1-57

10.73
69.79
12.40
0 81

415
54.36
27.51
10.68

0.76
41.83

35-07
21.63

4.40

59-91
22.23

3-24

4.06

0.40

100.
2.52

100.
2.40

100.
3.21

100.
4-03

100.

1.40

3"

6.80

5.80

391

4 -.37

0.60

454

I. 00

2.00

4-74

4-75

4.92

7.81

8 3'

12.43

8.64

572

I.20

3.82

6 80

6.20

1-75

1.96

1.44

1.92

2.25

0.77

2.13

1.71

0.16

1.35

5-3°

1.40

2.07

1.86

1.07

19.70

13 17

1.70

24.68

3.01

87.10

72 -45

79.30

69.30

68.32

76 -47

77 65

63 -57

55.46

46.00

46.82

61.91

9.00

20.79

14.00

28.00

22 99

19-47

18.29

i6.6i

23 -94

19.60

19.71

27.09

\

0.25

0.74

3-74

r

4.90

2. 81

3-70

541

1.30

1.30

6.62-

0.66

0.84

O.I2-

1. 18

3-32-1

1.23

1.78
0.65

1.23J

...3]

0.48
2.42

1

[

2.32 -j

1.80

Fine Earth (No. 5).

46 49 75 78
Analysis of Soil.

252

APPENDIX.

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COMPOSITION OF MINERAL FERTILIZERS.

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254

APPENDIX.

ASH AND NITROGEN CONSTITUENTS OF AGRICULTURAL

PRODUCTS.

The following table is taken from " Mentzel und von Lengerke's land-
wirthschaftlicher Kalender fiir 1888."

Compare " Aschen-Analysen von land- und forstwirthschaftlichen
Producten, Fabrik-Abfallen und wildwachsenden Pflanzen," von E.
Wolff (Berlin, P. Parey, 1871); also " Zweiter Theil, Untersuchungen aus
den Jahren 1870 bis 1880" (Berlin, 1880).

Ill the two latter publications are given, beside statements of single
analyses and explanatory notes, tables showing the ash composition per
thousand parts of the materials in dry state.

In the first-named work, however, and in the following table, these
results of E. Wolff have been adjusted to represent the ash composition
of air-dry or, in certain cases, fresh or green products. At the same
time the average nitrogen content per mille has been added.

This has been done in order to exhibit a more convenient table for
service in reckoning in connection with fertilization and cropping of
land.

The quantities named are, of course, to be modified to correspond with
the quantity of water present in any particular case. The lailer varies
greatly, especially in green and root crops.

It must also be borne in mind that the composition of the ash of all
plants and parts of plants ranges widely with varying conditions of
growth. Calculations, therefore, based on these averages have in the
solution of agricultural problems only a relative value, and primarily as
foundation for further reckoning.

EXPLANATORY NOTES.

3 Manured with liquid manure.
6 From Baltic sea.
j Poa maritima (Huds), or
' Glyceria maritima (Wahl).
g Meadow hay from regions where the

disease Osteocele in cows, abounds.
10 Norway.

12 Lolium perenne.

13 Phleum pratense.

14 Dactylis glomerata.
16 Trifolium pratense.

21 " repens.

22 " hybridum.
«j " incarnatum.

24 Medicago lupulina.

25 " sativa.

26 Onobrychis sativa.
28 Ornilhopus sativus.
2g Vicia (sativa ?).

32 Spergula arvensis.

35 Urtica.

36 Elodea canadensis.
40 Lolium perenne.

48 Sorghum vulgare.

49 Panicum.

50 Trifolium pratense.

56 Trifolium incarnatum.

60 Ornithopus sativus.

ASH A AW NITROGEN COXSTITUENTS.

255

64

Spergula arvensis.

67

Urtica.

68

Elodea canadensis.

75

Brassica napus esculenta.

81

Helianlhus luberosus.

86

Brassica napus esculenta.

88

" oleracea capitata.

89

Pastinaca saliva.

92

Convolvulus batatas.

93

Brassica oleracea gonglyoides.

94

Raphanus sativus radicula.

95

Apium graveolens.

98

Cynara scolymus.

99

Brassica oleracea capitata.

100

" " sabauda.

lot

" " botrytis.

102

Lactuca sativa.

103

" " capitata.

104

" (var.?).

106

Allium schoenoprasum.

107

Young

109

Old.

121

Panicum miliaceum.

126

Vicia faba.

127

Phaseolus vulgaris.

128

Soja hispida.

130

Vicia sativa.

139

Brassica rapa (varieties).

141

" oleifera.

143

Papaver (var. ?).

M4

Linum usitatissimum.

148
149
150

»74

175
176
177
192
210

2H

214
221
222
223
224

246
247

260
261

286

Coriandrum sativum.

Foeniculum officinale,

Anetlium graveoleus.

Vicia faba.

Phaseolus vulgaris.

Soja hispida.

Vicia sativa.

Camelina sativa.

Phragmites communis.

Carex.

Scirpus species.

Zostera.

Erica.

Pinus. ]

Larix. '

Picea.

Abies.

Residue from spirit manufacture.

Residue from starch manufacture.

From beet-sugar manufacture, in which
the roots are pressed.

From beet-sugar manufacture, in which
the sliced roots are extracted by " dif-
fusion process."

Residue separated from sugar-beet
molasses.

From Helianthus annuus.

From sesamum orientale.

Myrica cerifera (?).

Holstein.

Melolontha vulgaris.

256

APPENDIX.

ASH AND NITROGEN CONSTITUENTS OF AGRICULT'TRAL PRODUCTS,
By E. Wolff, Hohenheim.

Average Amounts in iooo Parts, by Weight, of the Green or Air-dry

Substance.

No.

Substance.

I. HAY.

Meadow hay

Young grass and rowen..

Grass, manured

Rich pasture grass

5 Best marsh hay

6 Salt meadow hay

Sea spear-grass

Alpine hay

Unhealthy hay

Forest hay

Sour grass

Rye grass

13 Timothy

14 Orchard grass

15 Cereals in flower

16 Red clover, quite young.,

17 " " in bud

18 " " in flower

iQ " " ripe

20 Clover grass

ai White clover in flower. . .

22 Bastard clover

33 Incarnate clover

24 Nonesuch

25 Lucerne

26 Esparsette

27 Anthyllis vulneraria

28 ^Seradelia

29
30
31
32

Green vetches in flower

Green peas

Lupine hay

Corn spurry

33 [Buckwheat in flower

34 [Green rape beginning to flower.

35 Nettles ..

36 Water weed

140
143
143
143
150
167
i6s
160
150
160
,65
160
167
167
160,
167
167'

167 21

167 22

'\
167 22

167 27

167^19

160 21

160 29

114 29

169 24

I

5

59-

I

76.

7

80.

5

82.

72.

65.

57-

•5

29

•4

44-

.6

26.

37-

■3

58.

•5

58

50

59

•5

82

■5

68

■7

57

•5

44

,8

54

.2

61

.0

40

■5

5°

■3

53

.0

62

. I

45

. I

S3-

.6

81.

7

56-

9

62.

•4

34-

.2

S6

•4

69.

■9

68.

•3

120.

•3

166.

nj

n

0

CX

16

0

22

3

35

0

31

6

27

2

19

I

6

6

7

7

12

0

7

7

20.2
20.3
16.7

19.3
29.7

25-3
18.6

10. o
25.6

'3-'
II. 1
II. 7
16 8
14.6
13.0
M-5
3'-9
19.7
23.2
8.0
19 7
21.4
22.6

38.5
23.6

9-5
10.4

9-5
10. 1

7.2

8-S

2-5

7-1

S-4

2-5

7.0
4-3
4-7
3-1
3-4
23-5
20.7
20. 1
15-8
5-6
18.4
13.6
16.0
14.9
25.2
16.8
27.7
18.2
16.3
'5.6[
8.8j
10.8
27.9
iS.o^
33-0

52-3;

. I

4-

. I

5-

.2

9

.6

7-

-9

5-

.8

4-

-7

2.

•4

2.

•7

2.
1

.8

I.

•3

6.

•9

6.

•4

3-

•7

5-

.6

10.

.6

6.

■3

S-

•9

4-

-3

5-

.8

7-

.0

4-

.1

3-

5

4-

. I

5-

.0

4-

-5

4-

.8

9-

.6

6.

■3

6.

•3

S-

.8

8.

.2

4-

•7

7-

.6

9-

•4

16

3-1
4-1
4.6
2-7

2-3

4-1

1 .0

1-4
1.8
1-4

3-7
2-3
1-7
1-3
i-S
i.l

1-7
1.9
1.4
2.8
4-5
1.6

13
2.2
3-6
••4
0.7
3-1
3-4
S-i
1.9
1.9

2-5

9-5

lO.O

6.8

17. 2
19.4

6.9
15.9
15.6
12.6
27.5

7.2
17.0

9.9

13-8

18. s

18.8

16.7

24.7

2-5

1.8

1.6

30
II . I
2.7
1.6
8.2
1-9
5-9
3-7

3-7
4 5
9.9
8.4
10.5
7-1
6.4
0.7
2.1
I.I

6.1

30
3.6
2.3
3-3
2-4
2.2

1-3
1 .2
2.6
2.2
1.8
4.8
1.9
1.8
1.7' 0.6

7.0 2.1

I

1.1 1.4

0.8 2.0

2.4 0.6

0.8 4.4

0.8 0.5

3.2 5.0
4.8 8.0

24.0 6.1

ASH AND NITROGEN CONSTITUENTS. 257

ASH AND NITROGEN CONSTITUENTS OF AGRICULTURAL PRODUCTS.

No.

Substance.

II. GREEN FODDER.

Meadow grass in flower

Young grass and rowen

Rich pasture

Rye grass ....

Timothy

Orchard grass

Sweet grasses in general

Rye fodder

Green oats

Cereals in flower

Corn fodder

Sorghum in flower

Panic grass

Red clover, quite young

" " in bud

" " in flower

Clover grass

White clover in flower

Bastard clover

Incarnate clover

Lucerne beginning to flower

Esparsette in flower

Anihyllis vulneraria in flower.. .

Seradella

Green vetches

Green peas

Green lupine

Corn spurry

Buckwheat in flower

Green rape beginning to flower.

Nettles

Water weed

Hop refuse from brewery

III. ROOT CROPS.

Potatoes

Artichokes

Beets

Sugar beets

Turnips

Rutabagas

782
700
700
700
700
760
810
785,
829

773
750

820 S

750
80:;

740
800
830
SoOj
820
815'
850
800
850
870
830
880
856

750 3-4
800 3.2
880! 1.8
815 1.6
920'
870

175
18. 1
21 . 1
20.4

20.5
17.8
22. 1

6-3
4.2

5-°
0.4
4 °
7-4
40
4-7
3-7
64
4 3
8.6

1-3
9.2
[ .0
0.9
9.6
2.1
3-9
6.2

3-5
24

24.0

4 6

9-5
9.8
9.1
71
6 4
7-5

8 1.2

5 1-2

6 1.2
5 0.4

7 0.7
1 0.5
7 0.7

' 0.5
0.4
0.4
I.I
06
1.6

1-3
t.6
1-5
0.7
1.4
I.I
0.7
0.9
0.7
o-S
0.7
i.o
1.4
0.6
1.6
1.6
0.4
1.6
1.4
0.6

a.-Sl

1-3
"•3
0.6
0.6
0.6
0-5
I.I
0.9
0.6
0-5
05
0-3
0.6

o-S
0.4
0.6
0.4
o. I
0.5
03
0.4

O. I

1 .1

O I

0.8

i-S
0.9
0.0

o 4
0.9
o 3

03
0.5

258 APPEXDIX.

ASH AND NITROGEN CONSTITUENTS OF AGRICULTURAL PRODUCTS.

No.

Substance.

Carrots

Chicory

Sugar-beet heads

IV. LEAVES AND STEMS
OF ROOT CROPS.

Potatoes, nearly ripe.

Potatoes, unripe

Jerusalem artichokes.

I Fodder beets

Sugar beets

Turnips

Carrots

Rutabagas

Cliicory

Cabbage

90

9«
92
93
94
95
96
97
98
99
100
101
102
103
104
105
J 06
107
108
109
no

V. GARDEN VEGE-
TABLES.

Parsnip

Asparagus shoots

Horse radish

Sweet potatoes

Kolilrabi roots : . . .

Garden radish

Celery tubers

Cucumber fruit, entire.

Squash fruit, entire

Artichoke

Cabbage, heart

Savoy cabbage

Cauliflower, heart

Lettuce

Head lettuce

Roman salad

Squash

Chives

Onions, bulbs

Onions, leaves

Onions

Edible mushrooms. . . .

77°: 4-9
82:; 6

800 1
905!
897'
898
822
884
S50

793,
933!
76/1
758!
850
I
933,

841
956
900

8ii|
900
87.1
904
940
943!
9251
903]
820
876
908
860

5 4
32
4-3
2.4
4.8
1.9
2-4
1.6
1 .1

30
5-3
4.0

2.2
2.0

4 9
6.2

4-5
3-4
2.7
4-7

6.7
9.6

19.7
16.5
14 5
14.6

'5-3
II. 9

23.9
19.6
16.5
15-6

10. o

5.0
19-7J

7-4j
12 3

4-9
17.6

5.8

4-4

-lO.I

9.6

14.0
8.0
8.1

10.3
9.8

16.0
9.9
8.4
7.6
7-4

10. o

5.8

5-4

I .2

7-7
3-7
4-3
1.6
7.6
2-4
0.9

2-4

4

3-9

3-6

3-7

3-9

2-5

2.7
3 3
2.6

3'
2.5
5-1

0.2
0.9
0.4
0.5
0.8
1 .0

0.6
0.9
0.7
0.8
1-4
0.5
0.8
0.8
3-5
5-7
0.4
1.2
0.5
0.2
o 2;

0.9 0.4
0.5 0.3
0.9 1 . 1

6.5I o

3-3 0-4
2.8 0.6

1-4 o

I
0.7I 0.2

u

1.2 0.4

1.9 I.O

2.1 0.5

0.9 0.3

1.7; 0.3

1.61 0.3

o.i] 0.3

1.0

0.9

2.0

0.8
2.7
0.5

2.2
1.2
1.6

3-9
1. 1

2.1

1.6

0.7

1 .0
I . I
1.6
1-5
1-4
0.6
1-3
3-4

o.i 0.4
°-3j o.S
0.2 0.3

0.9

\

X.2,

3.a

o-5|
...

0.5

2.4

2. I
0.6
O.I

0.2
0.5

0.3

°-3

0.4
0-3
0-3
0.9
0.6
0-5
2.8
0.4

0.2
0.5

0.7
o-S
o 3
0.7
0.1
0.7

03
1.3 0.4
0.8 0.8
0.4

0-3
0.7
0.3
0.6

1.0
0.4
03

0.6; 0.5
0.7 0.2
0.1: 01

ASH AND NITROGEN CONSTITUENTS. 259

ASH AND NITROGEN CONSTITUENTS OF AGRICULTURAL PRODUCTS.

No.

^'3
114

J15
116
117
118
119
120

121
122
123
124
125
126
127
128
129
130

132
133

134

"35
136
137
138

'39
140
141
142
M3
>44
•45
146

>47
148
149
150
151

Substance.

VI. SEEDS AND FRUITS.

Winter wheat

Summer wheat

Spelt, without husks

Spelt, with husks

Winter rye

Summer rye

Summer barley

Winter barley

Oats

Indian corn

Millet '

Sugar millet

Sorghum

Buckwheat

Peas ,

Horse bean

Field bean ,

Soja bean

Lupine

Common vetch

Red clover

White clover

Esparsette

Seradella

Beets

Sugar beets

Carrots

Chicory

Turnips

Rape

Summer rape

Mustard

Pippy

Flax

Cotton

Hemp

Caraway

Coriander

Fennel

Dill

Madder root

144
143
143

148

143
143
143
145
143
144
140
1 40
140
140
143
145
ISO

14
35
40
39

ioo|53

130 56

M3

150

150

160

120

140

146

120

130

125

118

120

130

147

118
77

122
130
135
134
133
144

.a
<

i

0

«

.5

.X

1

- 1

2 .
■§.."5

0

5.-C
c-'o

n

(3

_o

16.8

S-2

0-3

o-S

2.0

7.9 0.1

03

0. 1

18.3

S.6

0.3

0-5

2.2

9.0! 0.2

03

0.1

14.4

4-3

0.7

0.6

1.8

6.5'....

O.I

36.6

5-7

0.4

I.O

2.6

7.6: I.I

17. 1

0.2

17.9

5-8

0.3

o-S

2.0

8.5 0.2

0.3

o.i

18.0

6 2

0-3

2.2

9-2 ...

0.2

22.3

4-7

0.5 06

2.0

7-8' 04

5-8

0.2

17.0

2.8

0.7

0.1

2.1

5-6^ 0.5

4-9

26.7

4 8

0.4

1.0

1-9

6.8 0.5

10.5

0.3

12.4

3-7

0.1

03

1.9

5-7

0.1

03

0.2

29.5

3-3

0.4

0.2

2.8

6.5

0 1

iS-6

O.I

23-4

3'5

2.0

0.2

3-1

5-8

0.2

8.6

16.0

3 3

0.5

0.2

2.4

8.1

1.2

II. 8

2.7

0.7

0-5

1-5

S-7

0.2

0.2

23-4

lO.I

0.2

I . I

1.9

8.4

0.8

0.2

0.4

31.0

12.9

0-3

1-5

2.2

12.1

i.i

0.2

O-S

27.4

12. 1

0.4

1-5

2.1

9-7

I.I

0.2

0.3

28.3

12.6

0.3

1-7

2-5

10.4

0.8

0.1

37-0

II-4

0-3

2.8

4-5

14.2

3-2

0.1

0.3

26.6

8.0

2.1

2.2

2.4

9.9

1.0

0.3

0.7

38.3

|i3-5

0.4

2-5

4.9

14-5

0.9

o.S

0.5

33.8

12.3

0.2

2-5

3-9

II. 6

1.6

0.8

0-5

38.4

'11. 0

i.i

12.3

2.6

9.2

1.2

0.3

0-5

28.4

8.2

2.2

S-S

2-7

7-8

0.6

1-7

48.8

9.1

8-5

7.6

8.6

7.6

2.1

I.I

S-3

45-3

II. I

4.2

10.2

7-3

7-S

2.0

0.8

1.0

74.8

"4-3

3-5

29.1

S.o

II. 8

4.2

4.0

2.8

54.6

6.5

4.6

17-3

S 9

16.5

2.4

0.6

o-S

34-6

7.6

0.4

6.1

31

14.0

2-5

0.2

39-2

9.6

0.6

5-5

4.6

16.6

0.9

o-S

o.l

34-9

7-7

5-2

4-7

14.9

2-3

36.5

5 9

2.0

7.0

3-7

14.6

1.8

0.9

0.2

51-5

7.0

0.5

18.2

4.9

16.2

1.0

1-7

2.4

32.6

10. 0

0.7

2.6

4-7

»3S

0.8

0.4

33-8

10.9

2-3

1-9

5-6

10.5

0.7

0. 1

0.5

46 -3

9.4

0.4

10.9

2.6

16.9

0.1

S-5

46.4

12.2

3-°

8.4

38

"■3

2.5

2-3

1-4

41.2

14-5

0-5

0.1

5°

7.6

2.8

0.4

1.0

61.4

19.6

i-S

12. I

8.6

10. 1

o-S

0.2

2.1

54-7

17-3

1-3

14 5

4.1

95

3-7

1.4

2 7

62. 5

17.4

3-8

15-5

'7

51

2.3

6.8

3-9

26o APPENDIX.

ASH AND NITROGEN CONSTITUENTS OF AGRICULTURAL PRODUCTS.

No.

152
153
154
155
156
157
158
159
160
161
162
163

164

165
166
167

168
169
170
171
172
173
174
17s
176
177
178
179

Substance.

Grape seeds

Cocoanut, endosperm

Walnut, cotyledons

Horse chestnut, fresh

.A.corns, fresh

Grapes

Apples, entire fruit

Pears, entire fruit

Cherries, entire fruit

Plums, entire fruit

Gooseberries

Strawberries

VI. STRAW.

Winter wheat

Summer wheat

Winter spelt

Winter rye

Summer rye

Barley

Oats

Indian corn

Buckwheat . •

Peas

Horse bean

Field bean

Soja bean

Common vetch

Lupine

Rape

Poppy

VIII. CHAFF AND PODS

Winter wheat

Winter spelt

Winter rye

Barley

Oats. ...

Rice husks

Indian corn cobs

Bean pods

Lupine pods

5-8

22,7

9-7
II. 7
12.0
9.8
8.8
2.2
3-3
3-9
2.9

3-3,
3-3

46.0
38..
50.1
38-2,
46.7
4S-9
61.6
45-3
S'-7
43I
44-9
40.2
327
441
42.6

41-3
48.6

92
.6 81

82
4.8 II
6.4 7

90

2-3

6.8
7.2

4-5
54-7
19. 1

6.3

II. o
S-2

8.6
II. 7
10 7
16.3
16.4
24.2

9.9
19.4
12.8

50
6.3

17-7
"•3
18.4

0-5

o.8|
0-3

o. I

0.1

0.6

i
03

O. I

0.3
0.9

8.4

1-7

••7

0 3

5 2

0-3

9-3

I.I

4S

2.9

1-4

1-4

2.3

0.1

55-5

1-3

9-4

1-3

2.7

2.6

2.9

3-1
4.0

3-3
4.3
4-9
9-5
I.8JI5-9
0.8 12.0

3.2 II. I

I
0.7 14.6

6.9 15.6

1-3 9-7

3-9|"-7

0.6 14.7

1-7
2.0
3-5
12.5
4.0
0.9
0.2

9, 1
5 5

0.9 2.0

1.2 2.6

1.2 2.S

1.2 2.8

1.21 1.9

2.3J 2.8

2.61 3.8

I. 91 6.1

3-5
2.9

2-5| 3-9

S-0| 3-'

3-7i 2.7

3-4| 2-5

2.5 2.5

3.1 1.6

I.I 5.6

'•S 2.4

IS '3

1.8 1.7

0.2 0.2

6 o 2.7

0.8 i.o

31.0
18 2
36.0
18.8
25.2
234
28.8

131

2-9
2 9
3-2

1.9

1.8
3-6
1 .2

2.6

S-S

74.7

60 4 ... .
66 . 4 0.4
85.6 0.8
50 4 o 8
80.7

1.31 0.2
0.3 1.0
0.9 0.3

ASH AND NITROGEN CONSTITUENTS. 26 1

ASH AND NITROGEN CONSTITUENTS OF AGRICULTURAL PRODUCTS.

No.

Substance.

190 Rape pods

191 I Flaxseed capsules

192 False flaxseed capsules.

^93

194
19s
196
197
198
199
200
201
202
203
204
205
206
207
208

212
213
214
215
216
217
2t8
219
220
221
222
223
224

IX. COMMERCIAL
PLANTS.

Flax stems

Flax stems, roasted

Flax fibre

Hemp stems

Hops

Hop stems

Hop, entire plant

Tobacco leaves

Tobacco stems

Madder root

Grape stalks

Pressed grapes

Wine dregs

Grape juice

Grape stalks and branches.

Tea leaves

Mulberry leaves

X. LITTER.

Reeds

Sedges

Bulrushes

Eel grass

Heath

Moss

Ferns

Broom-corn tops

Beech leaves in August.

Beech leaf.

Oak leaf

Pine leaf ,

Larch leaf

Fir leaf

Spruce leaf

Pruning litter

32.2
'5-7
25.0
34-8
24.6

4.1
35.6
4.0

70.1
53-9
43-3

33-5
60.0
56.0
146.7
16.6
20.6
48.7
13.6
21 .6
46.7
46.
12.

34-3
40.3
32.8
28.1

9-5
15.0

12,7

9-7
0-3
0.3

S-5
23.0
II. 2
17.9
40.9
28.2
14.0
10.9
17.2
33-4

3-1

4.1
16.4

7-3

6.0
20.2
16.9
17-7

2.1

3-4
8.6
4 8
4.4
2.3
3-5
1-3
1.6

1-3
2.7
7-4

33

iS-6

16.0

16.8

2.7
3-6
4.2

20 9
3-6
2.9
S.6
2.2
6.3

21 2
17. I

4.6

7-5
16.0
19.5
10.8

j-7 6.4
4-5 3-8
1.5 4.6

4.2
0.8
0.7
2.1
II. I
3-9
S.8
6.6
9.2

2-4
1.8
4.6

3.6J
0.6I
1.4
7.2
2.4

9 I

6 4

0 4

5 4

6 I

3 I

' 3

6 I

6 I

1 2

3 2

2 I

4 I
8 2

3 2
o 3

8; 0.8

2.0

2.0

34-7

0.7

I.I

1-7

0.4

0.5

4J i-o

o 0.9

o 0.5

3 0.6

■'1

o 0.6

0.8

1.4

0.8
4-5
3.6

1-7
1-3
0.8
31
10.9
2.9

13-3
8.1
1.6
I.I
0.8
3-8
3.2
0.1
0-3
2-4
7.2

II. 8
2.9
4-3
5-5

10. o

1-3
6.2
14-5
iS-4
1.8
19.6
18. 1

2-5

0.8

3-5
41
0-7

3

262 APPEXDIX.

ASH AND NITROGEN CONSTITUENTS OF AGRICULTURAL PRODUCTS.

No.

Substance.

XI. BY-PRODUCTS AND
RESIDUES.
2261 Wheat bran

227 iRye bran

228 j Barley-meal fodder

229
230
231
232
.233
234
235
236

237
238

239
240
241
242
243
244

24«

246

247
248
249

Barley bran

Oat husks

Buckwheat bran

Rice-meal fodder ...

Rice husks

Fine wheat flour . . . .
Wheat-bread flour.. . .

Wheat mill-waste

Rye flour

Indian-corn meal

Barley flour

Dried malt

Fresh malt

Malt sprouts

Brewer's grains

Beer

Potato slump

Potato fibre

Beet press-cake

Diffusion waste

Sugar-beet molasses.

250 Molasses slump

251 Flax refuse

252 Hemp refuse

253 1 Rape-seed cake

254 ! Flax-seed cake

255 ;Poppy-seed cake

256 I Walnut cake

257 J Beech-nut cake

258 Olive cake

259 ! Sunflower-seed cake.

260 ISesamum-seed cake..

261 Candlenut cake

262 I Peanut cake

263 Palm-oil cake ,

264 Cocoanut cake

265 Cotton-seed cake

22.4
23.2

17.6

4-3
27.2
19. 1

4.9

136 18.9
120,21.6

92 24.4

142 16.8

140 16.0

1
140 16.0

75 16.0

475 IO-4

80I36.8

7-8
o-S
2. 1

1-3
2.9
0.8

12.8

3-2

172
920
100
100

"3 50-5
122 47.2
115 51.0

137|55 3
160 20. I
138J 9.6

103 59-7
iii'sS.e

77 84-5

104 75.6
100 25.9
127 37.4
112 62.1

53-5
71.9

21 . 1
49-5
34-7
29.8
54-7

153-9
4-4

11. 2
26.5
16.9

5-9
20.0
25.6
14.6
67.6
10.6

3-1
6.6
1.1
II. I

3-3
82.6

12. I

6.1
6.5
57.0
5'-3
77-4
46.2
40.4
27 8
49-7
93-8
78. 5
39 7
26.1

53-3
66.4

15-3
19.4
5-5
8.3
4.9
9-7
6.1
2-4
1-5
3-5
8.4
6-5
1-7
5-8
4-4
2.5
20.8
04
I . I

3-0
0.2
3-8
0-3
58.7
9-5
0.8
0.7
13.0
12.5

2-3

15-3
6.1
7-9
II. 7
14.5
•7-5
15.0
5.0
19.6
15-8

0.3 1.4

0.6 2,9

1.2 1.2

0.5 0.8

.... 0.3

0.1 0.6

0.6 2.2

I
0.3, 0.2

0.2 0.4

0.5 0.6

i.o

....' 0.5

1.2 1.9
o.i| 1.5
0.3' O.I

0.5 0.3

... 0.5

o 9 2.5

O.ll I.I

I

10. I 4.1

1.3 O.I

0-3 3-5
o.i! 4.2
1.9! 7.1
0.8 4.3
2.3 27.1
.. 3.1

4-3 '2-4

1.9! 6 I

5-4

3-5

25.1

0.3 4.2

0.9 1.6
0.2! 3.1

i-S 5-5
.... 2.9

9.0
II. 4

2.8

3-1
1 .0
4.0

9-5
o. 1
0.4
1-4
3-5
1-4
0.9
2-7
2.2
1 .2

1-9
I.I
0.2
0.6
0.1
0.7
0.2
o 3

0.2
0-3
7-3
8.1
6.2
5-6
3-3
0.3
8.1
12.8
■3-5
5-2
4-5
3-0
10. 1

20. 9

34-4
10.8
9.1
1.6
10.7
23 8
41
2.2
S 6
11.7
8.2
2-7
95
9-3
5 3
18.2

3-9
1 .0

1-3
0.3
I . I

0.2

0-5
o. I
0.4

0-3
20.0
162

3»-7
20.2
9.1

2-5

21.5
32.7
40. 1
13. 1
II .0
13.0
30-5

0.4

O. I

1.6
0.2
04
o. I
3-4
1-7
» 9
06
0.6
1 .2
1 .0
1-7
0-3
0.9
05
1.8

0.6
0-5

0.1

0.2-

0.4
O. I
8.2

O-S

O. I

0.4
0.4

0.5

O. I

o 4
0.2
0.3
0.6
0.8
0-.9

AS/I AXD XITROGEN COX STITUENTS. 263

ASH AXD XITROGEN COXSTITUEXTS OF AGRICULTURAL PRODUCTS.

No.

266
267
268
269

SUBSTAN'CE.

6
7
8
279
280
281
282
283
284
285
286

XII. ANIMAL PRODUCTS

iCow s milk

jSour milk

I Colostrum

Cow's milk whey

Goat's milk whey

Sheep's milk

Parmesan cheese

Common cheese

Hand-made cheese

Gruyere cheese

Ox blood

' Mammal's meat ,

Meat-meal fodder

Hen's eggs, without shells

I Li ve ox

I Live calf ,

I

Live sheep

Live hog.

Washed wool ,

Unwashed wool

, Fresh May-bugs

c

§

J3
<

875

5-4

7-2

9"

4.6

7.9

730

30-7

II. 8

933

0.9

5-4

920

»-S

5-9

816

II. 2

7-3

322

370

39-8

513

51.2

50.1

480

52-3

68.4

3S8

43-5

72.9

790

32.0

7-9

763

35-2

10.2

"5

116. 5

15-9

737

zo.o

'A

597

26.6

46.6

662

25.0

38.0:

591

22.4

3..7|

128

20.0

21.6

520

94-4

9.8

150

54-0

70.8

704

30.1

•3-4

1-7

2.1
0.9

J-7
2.3
1.6
I.I
6.6
3-3
1.8
0.6
3-8
0.9
1.6

1-7
2.4
1-5
1.8
1.9
56.2
5.0

1-7
1-7
4-1
i.o
0.4

2.1
14.8
17-7

1-7
13.0
0.1
0.3
3-6
1.0
20.8
16.3

13-2
9.2
2.4
1.8
0.4

. La

o -j;

0.

3-

.6]i8.

0-5 13-
0.4 12.
0.4J 8.
061.

0.4

•7j 3-4
.6 0.2

0.1
0.1
0.1
0.1

0.1
0.1

0.2

2-5
2.0
0.2

1.0
0.9

'•3
0.8

»-7

0.6
0-5
3-7
30.1
24-5
2.7
O-S
0-3
0.8
28
3.0

2.2
1.2
0.8
32

264

APPENDIX.

I.
FERTILIZING CONTENT OF AMERICAN FEEDING-STUFFS.

Substance.

GREEN FODDERS.

Alfalfa

Apple-pomace silage

Clover (alsikc)

Clover (red)

Clover (scarlet)

Clover (white)

Corn fodder

Corn silage

Cow pea

Flat pea {Lathyrus syhestris)

Horse bean ( Viscia /aba)

Hungarian grass (German millet)

Italian rye grass

Lupine (white)

Lupine (yellow) .

Millet (common)

Millet (Japanese)

Perennial rye grass

Oat fodder

Orchard grass

Prickly comfrey

Rye fodder

Serradella

Soja bean ....

Sorghum fodder

Timothy

HAY AND COARSE FODDERS

Alfalfa

B.trley straw

Buckwheat hulls

Carrot tops (dry)

Clover (alsike)

Clover (red)

Clover (scarlet)

Clover (white) .. .

Corn fodder (with ears)

Corn stover (without ears)

Cow pea (entire plant)

Hay (mixed)

Hungarian grass

Japanese buckwheat

Moisture.

Ash.

Nitrogen.

Phospho-
ric Acid.

Potash.

Per cent.

Percent.

Per cent.

Per cent.

Per cent.

70.25

2.30

0.72

0.13

0

.56

75.00

1.05

0.32

0.15

0

40

81.80

I 47

0.44

0. II

0

20

80.00

0-53

0.13

0

46

82.50

0.43

0.13

0

49

81.00

0.56

0.20

0

24

78.61

4.84

0.41

0.15

0

3.3

77-95

0.28

0. II

0

37

78.81

1-47

0.27

0. 10

0

31

71.60

?-93

1.13

0.18

0

58

74-71

0.68

033

I

37

74-31

039

0. 16

0

55

74.85

2.84

0.54

0.29

I

14

85-35

0.44

0-35

I

73

83.15

0 96

0.51

0. II

0

>S

62.58

0.61

0. 19

0

4'

71-05

0-53

0.20

0

34

75.20

2.60

0.47

0.28

I

10

83 . 36

1-31

0.49

0.13

0

38

73-14

2.09

0 43

0. 16

0

76

84.36

2-45

0.42

O.II

0

75

62. II

0-33

0.15

0

73

82.59

1.82

0.41

0 14

0

42

73.20

0.29

0-15

0

53

82. ig

0.23

0.09

0

23

66.90

2-IS

0.48

0.26

0

76

6-55

7.07

2. ig

0.51

I

68

11.44

5-30

••3'

0.30

2

09

11.90

0.49

0 07

0

52

9.76

12.52

3.13

0.61

4

88

9.94

II. tl

2-34

0.67

2

23

"■33

6.93

2.07

0.38

2.

20

18.30

7.70

2.05

0.40

I .

3>

2-75

0.52

I.

89

7.85

4.91

1.76

0-54

0.

89

9.12

3-74

1.04

0.79

I .

40

10.95

8.40

I -95

0.52

I

47

11.99

6.34

1. 41

0.27

I .

55

7.69

6.18

1 .20

0-35

I

30

S-72

.63

0.85

3-

32

FERTILIZING CONTENT OF AMERICAN FEEDING-STUFFS. 265
FERTILIZING CONTENT OF AMERICAN FEEDING STUFFS.

Substance.

Moisture. Ash. Nitrogen. Phospho- p ^ ^
I ^^ nc Acid.; ">••"=>"

Kentucky blue g^rass

Meadow fescue (Festuca pratensis)

Meadow fox tail (Alopecurus pratensis).
Meadow 03X%xaS'/,(ATr he nateer unt arena

cfum)

Millet (common)

Millet (Japanese)

Oat straw

Orchard grass

Red top

Rowen (mixed grasses)

Rye grass, Italian

Rye straw

Rye grass, perennial

Salt-marsh hay

Sainfoin

Serradella

Scotch tares

Soja bean (straw) ,

Soj.i bean (whole plant)

Timothy ...

Wheat chaff

Wheat straw

GRAINS AND SEEDS.

Corn

Barley

Buckwheat

Millet (common)

Millet (Japanese)

Oats

Rice

Rye

Soja beans

Sorghum seed

Wheat (spring)

Wheat (winter)

MILL PRODUCTS.

Barley (ground)

Corn meal

Corn and cob meal

Oats (ground)

Pea meal

1
Percent.

10.3s

8.89

IS-3S

15-35

9-75

10.45

9.09

8.84

7-71

18.52

8.71

7.61

9.13

5.36

12 17

7-39

15.80

13.00

6.30

7.52

8.05

12.56

10.88

14.

14. 10

12.68

13.68

18.17

12.60

14.90

18.33

14.00

14-35

14-75

13-43

12.95

8.96

11.17

8.85

Percent,

4. 16
8.08
5-24

5-80

4.76

6.42
4-59
9-57

325
6.79

7-55
10.60

6.47

4-93
7.18
381

0.S2
4.99
1-57

2,06
1.41

3-37
2.68

Per cent.

1. 19

0.99
1-54

1.16
1.28
I. II
0.62
1.31
1.15
1.61
1. 19
0.46
1.23
i.i8
2.63
2.70
2.96

1-75
2.32
1.26
0.79
0.59

I.«2
1.48
1.44
2.04

1-73
2.06
1.08
1.76
5-3°
X 48
2.36
2.36

I 55
1.58
1.41
1.86
3.08

Per cent.

0.40
0.40
0.44

0.32
0.49
0.40
0.20
0.41
0.36

o 43
0.56
0.28
0.56
0.25
0.76
0.78
0.82
0.40
0.67

0-53
0.70
o. 12

0.70
0.81
0.44
0.85
0.69
0.82
o.iS
0.82
1.87
o.8i
0.70
0.89

o 66
0.63
0.57
0.77
0.82

Per cent.

1-57
2.10
1.99

1.72
1.69
1 .22
1.24
1.88
1.0a
1.49
:.27
0.79

1-55
0.72
2.02
0.65
3.00

0.90
o 42
0.51

0.40
0.42
0.21
0.36
0.38
0.62
0.09
0.54

J -99
0.42

0.39
0.61

o ^4
0.40
0.47
0.59
0.99

266 APPENDIX.

FERTILIZING CONTENT OF AMERICAN FEEDING-STUFFS.

Substance.

BY-PRODUCTS.

Apple pomace

Brewers' grains (dry)

Brewers' Grains (wet)

Buckwheat middlings

Corncobs

Cotton-seed hulls

Cotton-seed meal

Gluten meal

Hominy feed

Linseed meal (old process)

Linseed meal (new process)

Malt sprouts

Rice bran

Rice hulls ^screenings)

Rye bran

Rye middlings

Starch feed (glucose refuse)

Wheat bran

Wheat middlings

Wheat screenings

ROOTS AND TUBERS

Carrots

Beets (yellow fodder) ,

Beets (red) ,

Beets (sugar)

Mangel-wurzels

Potatoes

Ruta-bagas

Turnips

FRUITS AND NUTS.

Apples

Chestnuts

Grapes

Peanut vines . ..

Peanuts

Per cent.

80.50
6.98
75.01
14.70
12.09
10.63
9.90
8.59
8.93
8.88

7-77
10.38
10.20
10.30
12.50
12.40

8.10
11.74

9. .8

8 41

85.30
40.00
83.00
10.00
10.00

Ash.

Percent.

0.27
6.15

1 .40

0.82

2.61

6.82

0.73

2 21

6.08

5-37
12.48
12.94

9.00

4.60

3-52

6.25
2.30
6.27

g.22
0.9s

I-13
1.04
1 .22
0.99
1 .06

0.39
>-32
0.50
12.36
2.21

Nitrogen.

Per cent

23
05

0.15
o. 19
0.24
0.22
o 19
0.21
o. 19

0.18

0.13
1.18

0.16

Phospho-
ric Acid.

Per cent.

0.02
1.26
0.31
0.68
0.06
0.18
2.68

0-33
0.98
1.66
1.83
1-43
0.29
2.67
2.28
1.26
0.29

0.09
0.09
0.09
o.io
0.09
0.07

O. 12
0.10

0.01

0-39
0.09
0.29
0.82

Potash.

Percent.

0.13
'•55
0.05

0-34
0.60
1.08
1.79
0.05
0.49
'■37
'•39
1.63
0.24
0.71
1.40
0.81
0.15
1.61
0.63

0.51
0.46
0.44
0.48
0.38
0.29
0.49
0-39

0.19
0.63
0.27

O.QO
0.88

FERTILIZING CONTENT OF AMERICAN FEEDING-STUFFS. 267

II.
PERCENTAGE COMPOSITION OF FERTILIZING MATERIALS.

3

'S
2

c
be
§

0
0.

Phosphoric Acid.

3

c
u

2

,0

Substance.

£1

_3

"o

10

•D

0

H

c

_o

U

Ammonite

5.88

"•33

O.IO

0.40
1 .20
1.27
S-25

3-43

O.IO

0 40

t.14

1. 51

1.70

35-89

28.28

17.00

33.25

17.60

Ashes (hard-coal)

Ashes (soft coal)

Ash'^s (lime-kiln)

i';.4';

48.50
28.08
34.00
44.89

2.60
2.66
3-4°

Ashes (wood-leached) ... .' 30.22
Ashes (wood-unleached).. . 1 12.50

0.14

Boiie-ash

7.00
4.60

Bone-black

Bone-black (dissolved)

15.40
0.40

1.30
7.60

Bone-meal

7.50

4 OS

2.60

5-50

7.10
4.30
10.52
7.25
8.20

18.50
13.68
1. 10
22.75
1.80
1.50

1. 31

16.50
13.19

10.75

0.56

Bone-meal (dissolved)

Carbonate of pot. and mag.

9.50
7.80
7-75

Carnallite

41.56

Castor pomace

'■75
8.85
3.10
3.10
1. 91
8.25
3.80
26.77
15.00
..83

0.06

9.60

Cotton-hull ashes

'•25

6.50

Cotton-seed meal*

Cotton-seed meal

Dried blood

12.50

12.75
40.09

7-31

14.81

10. 17

3-2J

87-75

4.82

1.50

1.50

12. og

50.00

2,00

7.60

'•93
1.40
15.00
61.50
2.25
1.50

0-5S
= •37

2.60
1.24

Dried fish

Guano, Bat

Guano, Caribbean

39-95

3.25

2.68

Guano, Peruvian

7-35
13.25

0.20

10.44
1. 10

2.65

'3^54
0.24
8.42
0.15
.3-5

0.15
51.48

3.20

4.10

Horn and hoof waste

Kainit

Kelp

1. 15

0.40

12.45

34.00

5.00

9.80
0.20
8.79

20.25
3'^94

33 25

Krugite

6.63

Marl (Kentucky)

•4
25
2.07

O.IO

Marl. N. J. green sand ..
Meat scrap

Muck

Muriate of potash

48 80

Navassa phosphate

Nitrate of pot. (saltpetre) .
Nit. of soda (Chili saltpetre)
Oyster-shell lime

34-27

37 45

13.09
15.70

0.85

45.19

0.05
0.18

0.18
0.08
24.50
28.13

15.20

55

o^35

0.60

Peat

Phosphate-rock (Florida). .

28.50
41.87

3-03

Phosphate-rock (S.Caro! ina)

0.27
II .

0.07
60

Phos.-rock (S.C, dissolved)

• Without hulls.

268

APPENDIX.

PERCENTAGE COMPOSITION OF FERTILIZING MATERIALS.

t

3
'S

2

c
U

£

I

Phosphoric Acid.

E

.2

c
be
™

0

Substance.

Soluble

Re-
verted.

0

c
U

20.93
I 58

33-46
3-25

0-39
3 55

46.51

Sewage-sludge, precipitated
Tan bark ashes

88 49
3.6.

63.06
1 .00
4-75
5.88
2-54

7 25

10.00

1.45

6.18

10.00

15.80

0.05

1. 19

20.50
"•33

6.70

3-71

2-35

6.50

0 05

2.04
3-25

25-50

O.IO

1. 61
1. 14

60.00

44 25

45 72

Sulphate of ammonia

Sulph. potash & magnesia.

2-57

48.66
2.22
4.20

3-42
0.59
0.80

3.00

Sulphate of potash . .

Sulph potash (high-grade)

Sylvanite

Tankage

Thomas' slag

Tobacco-stalks

33-40
51-50
16.65

5.02
8.20

3-92

0.30

5-10
3-06

11.80
23-49

0.65
0.70

035

0.65

0.6s

Wool-washings

O.II

III.

COMPOSITION OF FARM MANURES.

Substance.

Barnyard manure, average.

Cattle excrement, fresh

Cattle urine, fresh

Hen manure, fresh

Horse excrement, fresh —

Horse urine, fresh

Human excrement

Human urine

Pigeon manure, dry

Poudrette (night-soil)

Sheep excrement, fresh

Sheep urine, fresh

Stable manure, mixed

Swine excrement, fresh. ...
Swine urine, fresh .

68.87

77.20

95 90
10.00
50.00

o 49

-29

.58

1 . 10

0.44

I -.55
: .00
0.60
3.20
0.80
0-5S
1-95
0.50
0.60
0.43

0.43
.10

•49
0.56

0.35
1.50
•25
0.20
1. 00
0.30
CIS
2.26
0.60
0.13
0.83

0.85
0.17

1.09
0.17
1.90
1.40
0.31

O.OI

0.30
0.41
0.07

2.10

0.80

o 80
0.60

0.60
0.40

0.50
0.08

FERTILIZING CONTENT OF AMERICAN lEEDING-STVFFS. 269

IV.

MANURIAL VALUE OF FARM PRODUCTS.*

Substance.

Pounds Per Ton.

Nitro-
gen.

Alfalfa

Barley ..

Cheese

Clover hay

Corn

Cotton-seed meal . . .
Kentucky blue-grass

Linseed meal

Live cattle

Meadow hay

Milk

Oats

Potatoes

Sugar-beets

Timothy hay

Wheat

Wheat bran

Wheat straw

40.2
39 6s
Q0.60
40. 16
33.06

I.S5-65
21. 1

105.12
53 2
20.42
10.20
36.42
7.01

I 4.40

I 25.6
21 .0
37-53
4915
11.80

Phos-
phoric
Acid.

9

3

27.

9

0

IS-

23

0

5-

II

2

36.

II

8

7-

29

2

56.

7

3

29.

32

2

24.

37

2

3-

8

2

26.

3

4

3-

12

4

8.

3

2

II.

2

00

9-

9

80

33-

5

0

27.

10

6

'5

28

6

54

2

40

10

Potash

Value Per Ton.

Nitro-
gen.

©6 -74

15.40

6.83

5.62

23 06

•7-87
9.04
3-47
1-73
6.21
1. 19

6.38
8.35

Phos-
phoric
Acid.

50.63
1. 61
0.78
o.8j
2.04

2.25
2.60
0.57
0.24
0.87
0.22

0.74
2.00

Potash .

$0.62
0.20
1 .46
0.30
2.25

0.99
o. 14
1 .06
0.12

0.35

0.46

0.63
2.10

Total.

» 7 yg
17.21
9.07

6-75
28.35

21 . II
11.78
5.10
2.09
7-43
1.87

7-75
12.45

Ma-
norial
Value
of Sio
Worth.

$2.96
0.69
9.07
3.70

10. 12

7-54
1.18
5.10
0.88
3.86
0.12

2.58
7.78

• These figures indicate commercial, not agricultural, values; what the fertilizing ingre-
dients would cost in the market at the time the table vras arranged. This basis constantly
varies, and the table does not indicate actual value to the farmer, but the relative value of
the different products.

V.

FERTILIZING INGREDIENTS IN DAIRY-PRODUCTS.

Substance.

Butter

Buttermilk
Cheese ...
Cream

Nitro-
gen.

Phos-
phoric
Acid.

Potash

0.12^
0.48
3-93
0.40

0.04^
O.I7
0.60
0.15

0.036^
0.158

0.I20
0.130

Substance.

Skim-milk .

Whey

Whole-milk

Nitro-
gen.

Phos-
phoric
Acid.

0.56^

0.15

0.53

0.20^
0.14

0.19

Potash.

o. i85i<

0.181

0.175

270

APPENDIX.

VI.

AVERAGE COMPOSITION OF AMERICAN SOILS.

Constituents.

Fine earth

Total nitrogen
Insoluble silica.
Combined silica

Potash

Soda

Lime

Magnesia

Iron oxide

Alumina

Phosphoric acid
Sulphuric acid.
Carbonic acid
Volatile matter

97 -oo^
34

55 '

17
4>
32
»3
9'
3 02

5
17
26

50
41

92.50^
19

86.60^

•25

•44

1.20

•47
2.52
2.S8

.01
1.80

99.00^
17

99

64*

17

48

01

21

81

I

70

84

99

2

35

4

46

10

15

17

06

I

T2

■r6

100. It
.16

74.12
9.22
.67
.64
■ 56
.89

•67
5. 82

.12
•41

•5'
4.78

65.00^

.80

25.27

6.78

.29

•27

6.58

•4S

.69

3-57

.46

.24

724

44-49

.38^

60. 21
9.00

•90

.61

I .07

.84

3-49

9-15

•13

.11

■13

14.29

95

00?

51

33

7

16

34

32

2

06

4

39

9

56

6

04

13

38

17

98

67.96^

•IS

/8.19

3 99
•.3=
.16

•35

•38

3-43

4.01

.02

• 17

.65

♦5.62

• Water and organic matter.

t Average of 12 years' cultivation to wheat, corn, and oats, without fallow.

LIST OF AUTHORITIES

CONSULTED IN THE PREPARATION OF THE FOREGOING PAGES.

Adams. N?tural History of the Nile Valley and Malta. Edinburgh, 1873.
Agassiz, Systeme Glaciere. 1847.
Beilstein, Handbuch der Org. Chem. 1884.
BerthelOT, Bulletin de la Societe Chemique. Feb. 1886.
BOUSSINGAULT, Die Landwirthschaft, etc. Halle, 1851.
BuCKLAND, Reliquiae Diluvianse. London, 1823.
CoHN, Die kauflicheii Diingerniittel. Braunsweig, 1883.
VON COTTA, Rocks Classified and Described. London, 1877.

Katekismus der Geologie.
Credner, Elemenie der Geologie.

CuviER, Ansichten voii der Urwelt, Bd. I, 11. Bonn, 1826,
Dana, Manual of Geology.

System of Mineralogy.
Manual of Mineralogy.
Darwin, The Formation of Vegetable Mould.
Dawson, The Earth and Man. London, 1S73.
FoDER, Bcjden u. Wasser.

VON GOHREN, Agriculturchemie, Bd. I. Leipzig. 1877.
Grandau, Ag. Cliem. Analysen. Berlin, 1879.
Heim, Aus der Geschichte der Schopfung. Basel, 1872.

Die Verwitterung im Gebirge. Basel, 1879.
VON Humboldt, Cosmos.
Johnson, How Crops Feed. 1

How Crops Grow.
Johnston and Cameron, Agricultural Chemistry. Edinburgh, 1877.
JULIEN, Proceedings A. A. A. S. 1879.
Kellner, Agricult. Chem. Untersuchungen. Berlin, 1886.
Knop, Die Bonitirung der Akererde. Leipzig, 1872.
KONIG, Die Chem. Zusammensetzungder Nahrungsmittel. Berlin, 1882.
Le Conte, Compend of Geology. New York, 1887.

2/2 APPEXDIX.

LlEBiG, Chemische Briefe, 6te Ausgabe.

Die Cheinie in ihre Anwend. auf Ag. und Physiologic. Braun-
schweig, 1862.
Die Moderne Landwirthschaft. Braunschweig, 1854.
Theorie und Praxis in der Landwirthschaft. Braunschweig, 1856,
Reden und Abhandlungen. 1874.
Lloyd, The Science of Agriculture. New York, 1884.
Lyell, Antiquity of Man. London, 1873.

Antiquity of Geology. London, 1873.
Mallet, The Science of Cotton Culture. London, 1862.
Mantell, Wonders of Geology, London, 1866.
Mayer, Agricultur-chemie, Bd. L H. Held., 1876.
Meisner, Jahresbericht f. Ag. Chem. 1859-60.
Milne, Earthquakes. London, 1883.
Mulder, Chemie der Akerkrume. 1863.

MtJLLER, Die Aeltesten Spuren des Menschen in Europa. Basel, 1876.
MuLLER, PouiLET, Pfaundler, Lehrbuch der Physik, Bd. I, H, IIL

Braunschweig, 1879-81.
Mushketorff, Nature. Oct. 6, 1887.
DE Nadaillac, Prehistoric America. 1884.

Les Premiers Honimes et Temps Prehistoriques. Paris,

1883.
Die Ersten Menschen und Prehistorischen Zeiten. Stutt-
gart, 1884.
Neumann, Bau u. Entstehung der Japan. Inseln. Berlin, 1882.
Paige, Economical Geology. Edin., 1873.
Pfeffer, Pflanzenphysiologie. Leipzig, 1881.
Prestwich, Geolog}', Chemical, Physical, and Stratigraphical. London,

1885.
Pritch.ard, Natural History of Man. London. 1855.
ReiCHARDT, Agriculturchemie. Erlangen, 1861.
Rodwell, Birth of Chemistry. London, 1874.

RoscOE and Schorlemmer, Treatise on Chemistr)^ New York, 1885.
Rosenberg-Lipinsky, Praktische Akerbau. Breslau, 1879.
Roth, Algemeine und Chei... Geologic, Bd. L IL Berlin, 1879-83.
Settegast, Die Andwendung der Lehre Liebigs. Berlin, 1883.
Stockbridge. Rainfall, Soil-percolation, Deposition of Dew, etc. Bos-
ton, 1879.
Storer. Agriculture in some of its relations with Chemistry. New York,

1887.
Vogt. Ueber Vulcane. Basel, 1875,
Warrington. Chemistry' of the Farm. London. 18S4.
Wll.DT. Katechismen d. Ag. Chem. Leipzig, 1884.
Williams, Applied Geology. New York, 1887.

LIS T OF AU TIJORITIES. 273

WiTTSTEiN and MiJLLER, Organic Constituents of Plants. Melbourne,

1878.
Wolff, Diingerungslehre. Berlin, 1884.

PERIODICALS.

Agricultural Science.
American Chemical Journal.
American Journal of Science.
American Naturalist.
Annalen de Chem. et Physique,
Berichte d, Deutsch. Chem. Ges.
Bulletin de la Societe Chemique.
Bulletin of the Geological Society.
Centralblatt fiir Agriculturchemie.
Chambers's Journal.
Jahresbericht fiir Agriculturchemie.

Jahrbuch fiir Mineralogie.
Journal of the Chemical Society.
Journal of the American Chemical

Society.
Journal of the Royal Agric. Society.
La Nature.
Nature.

Petermann's Geolog. Mittheilungen.
Science.

Scribner's Magazine, 1887.
Versuch-Stationen (Nobbe's).

INDEX.

N.B.— A special index to Chapter V of Part Third will be found on pp. 381-2.

Acidic rocks, 66.
Ages of man, divisions of, 54.
Agricultural chemical geology, 3.
Agricultural products, percentage

composition, 218.
Agriculture, inception of, 55.
Air, action of, 107.
Albuminoid formation, 2oi,
Alluvian soils, 57, 147.

fertility of, 53.

formation, 57.
Alluvium, 69.

period, 45.
Alumina, 142.
Ammonia, 210.

of the soil, 136.
Amphibians, 18.
Amphibole, 63.
Angiosperms, 39.
Anhydrous minerals transformed by

water, 105.
Animal excreta, 130.
remains, 56.
Animals, 29, 53, no, 129.

allied to both birds and
snakes, 29.

disintegrating power of,
no.

species now extinct, 29, 53.

their relations to soils, 129.
Apatite, 9, 64.
Apocrenic acid, 134.
Archaean soils, 9.

time, 6.

iron deposits, 9.

Ash and sand cone, 72.
Atmospheric food assimilated by

plants, 199.
Atmospheric soil ingredients, 140.
Augite, 63.
Authorities consulted, 220, 221, 222.

B

Basalt, 67, 119.
Basic rocks, 65, 67.
Bog-iron ore, 44.
Bone-bed, 28.
Bronze age, 55.
Burrowing of animals, 130.

Calcite, 64, 117.
Carbonic acid, 144.
Carboniferous age, 17.

close of, 23.
fauna of, 18.
flora of, 18.
minerals of, 21.
rock formation

of, 21.
soils of, 23.
rocks, 19.

thickness of, 19
Cenozoic time, 37.
Chalk, 34, 70, 122.

formation, distribution of, 33.
era of, 33.
in England, 34.
Champlain period, 45, 52.
rocks, 52.
1 Changes in earth crust, 5.

276

INDEX.

Chemical geology, 2.

precipitation, 6i.
rocks, 57.
salts, 26.

transformallon in plants,
200.
Chlorine, 144.
Chlorite-schist, 68.
Cinnabar, 34.
Clay, 69, 120. ,

beds, 20.
schist, 67.
soils, 148.
Climatic zones, formation of, 38.
Coal, 43.

land, area of, 19.
measures, 19.
Coexistence of man with extinct

animal species, 53.
Color of soil indicating heat, 167.
Conglomerate, 68.
Continent formation, 84.
Contraction of soil from evapora-
tion, 163.
Coprolites, 43.
Crenic acid, 134.
Cretaceous formation, minerals of,

34-
Cretaceous formation, rocks of, 34.
soils of, 34.
period, 33.

climate of, 36.
geographi cal
changes, 36.
soils, fertility of, 35.
Trinoidal limestone, 18.
Crystalline rocks, compound, 65.
simple, 62.
slate formation, 8.

D
-Oelta formation, 100.
Devonian formation, 13.

divisions of, 15
fossils, 14.
minerals, 16.
rocks, 14.

Devonian rocks, distribution of, 15.

soils, 15.
Dew, direct cause of deposition, 175,
formation of, 173.

new theory, 174.
old theory, 173.
proofs of new the-
ory, 188, 189.
Diabase, 68, 119.
Diluvian epoch, 45, 113.
Diorite, 67, i ig.
Dislocation earthquakes, 85.
Divisions of earth-history, 6.
Dolomite, 64, 117.
Drift formation, 45.

material, composition of, 46,
soils, 147.
Dynamical geology, 70.

EarthjCavings, 25.

development, 70.
interior, composition of, 75.
temperature of, 86.
surface, contraction of, 79.
elevation of, So.
depression of, 80.

examples
of, 81.
Earthquakes, 84.

causes of, 85.
relations to geological

structure, 87.
shock, force of, 87.
systematic observation
of, 88.
Earth-worms, 131.

chemical action upon

soil, 132.
organic acids secreted

m. 131.
soil-producing capa-
city of, 132.
Electricity in soil, 191.
Eocene era, 40.
Erosion, 97.

notable examples of, 98.

IiYDEX.

277

Eruptive phenomena, 2S.

disturbances, 32.
Experiments to ascertain causes of

dew formation, 179-1SS.
Explosion earthquakes, 86.
Extraction of plant-food, 199, 200.
Evaporation from plants, 1S5.

at night,
1S6, iSS.
of water by various

plants, 159.
of water by soils, 160.

Feldspar, 62, 116.

Fiord valleys, 47.

First mammal, 30.

Flexibility of rock-masses, 83.

Flint, 35.

Footprints of birds and bird-like

reptiles, 29.
Fundamental geologic formation, 4.

Gases, absorption of, 211.

in soils, 191.
Geology, i.

Geological structure of the earth, 59.
Geysers, 77.

in America, 78.
Glacial action, limits of, 46.

excavations, 51.
Glacial action, evidences of, 47.
period, 45.

erosion of, 51,
phenomena, origin

of, 47.
theory, 49.
transportation of

plants, 50.
Glacier action. loi.
Glaciers, movements of, 51.

cause of southward move-
ment, 48.
Gneiss, 66. 118.

formation, primary, 8.
Granite, 66, 118.

Granular limestone, 68, iig.
Granulite, 66, 118.
Graphite, 7.
Grasses, 43.
Gravel, 147.
Greensand. 35, 69, 122.
Grit, 68, 120.
Ground-fog, 183.
Gypsum, 23, 64, 117.

H

Hardpan, 150.
Heat, 89, 166, 172.

its agency in rock metamor-
phism, 89.

its relations to soils, 166.

from decomposition, 166.

of soil, sources of, 166.

radiation from soil, 172.
Hekla geyser, 78.
Historical geology, 2.
Hornblende, 9, 116.
Hot springs, 76.

mineral constituents of,

77-
minerals deposits from,

77.
Humification, 128
Humin, 133.
Humus, 123, 133.

compounds, chemical action

of, 135-
compounds, composition of,

134-
soil, 150.
Huronian period, 8.

rocks of, 9.
Hydration, 93.
Hydrochemical metamorphism, 91,

92.
Hygroscopic power of soils, 163.
Hyperite, 68, 119.

I

Iceberg theory, 49.
Igneous rocks, 57, 61.
trap rocks, 29.

278

IXDhX.

Infusorial earth, 44.
Invertebrates, age of, 10.
Iron, 142.

minerals, 64, 118.

ore, 20.

oxides, 142, 143.

sulphide, 108.
Islands of volcanic origin, 72.

J
Jurassic formation, 31.
climates, 31.
minerals, 32.
rocks, 31.

distribution of, 32.
soils, 32.

K

Kant's hypothesis, 3.

Lake-dwellers, 54.
Land-formation, 38.

by oceans, loi.
Laurentian period, 8.
Lava cone, 71.

flow, characteristics of, 75.
stream, 74.
Leucite. 63, 118.
Lime, 141.

soils, 149.
Limestone, 14.

solution by water, 104.
Loam soils, 149.

M
Magnesia, 141.
Magnesile, 64, 117.
Mammals, 39.

age of, 37.
Man, 52.

age of, 37, 44.

prehistoric, 54.
Manganese, 143.
Marble, 68.
Marine fossils, 31.
Marl, 35, 70, 122, 149.

Mastodons, 53.
Mechanical rocks, 57.
Melaphyre, 67, 119.
Metamorphic rocks, 8, 61.
Mesozoic time, 27.

divisions of, 27.
Mica, 63, 117.

schist, 66, 119.
Millstone-grit, 20.
Mineral asphalt, 34.

coal, origin of, 21.

formation, process of,

22.
origin of, 21.
crystallization, 10.
fertilizers, composition of,

219.
oxidation, 105.
Miocene era, 40.
Moisture, its agency in rock meta-

morphism, 90.
MoUusks, 39.
Mountain chains, formation of, 38.

formation, 82.
Muck, 150.

N
Natural gas, 16.
Nebular hypothesis, 3.
Nepheline. 63, 118.
New red sandstone formation, 28.
Night temperature of air and soils,

178.
Nitrates, 113.
Nitric acid of the soil, 137.
Nitrification, 127, 137.

depth at which it may

occur, 13S.
its reverse, 140.
Nitrogen, atmospheric, 139.

converted into ammonia,

136.
forms of, 135.
in unavailable form, 128.
of the soil, 135.
Non-atmospheric soil constituents,
140.

INDEX.

2/9

Non-crystalline rocks, 68.

produ cts of
weathering,
120.

O

Oligoclase, ii6.
Olivine, 63, 117.

Organic decomposition, no, 126.
life, action of, 109.
ingredients of vegetation,

199.
matter in soils, 124.

percentage in soils,

125.
replenishment, 126.
rocks, 57.
Oxygen, 108.

Paleozoic time, 10.

Peat, 150.

Penetration of water in soils, 171.

Permian formation, 24.

end of, 26.

metals, 26.

rocks, 24.

distribution of, 24.

soils, 26.
Petroleum, 16.
Phonolyte, 66, 118.
Phosphate of lime, 43.
Phosphoric acid, 144, 209.
Plant-food, assimilation of, 199, 200.
Plant-growth, essential elements of,

197. iqS.
Plant-life, Archaean, 7.
Plants, decomposing effects of, ill.

their relation to soils, 123.
Pliocene era. 40.
Porphyry, 66, 118.
Potash, 141.
Potassium, 210.
Primitive rock, 5.
Protozoa, 7.
Pseudomorphism, 92.
Putrefaction, 126.

Q

Quartz, 62, 116.

reefs, 33.
Quaternary formation, 37, 44,

R
Recent period, 45.
Reptiles, age of, 27.
Rhizopods, 41.
Rhone glacier, 50.
Rocks, classification of, 59.

composition and decomposi-
tion, 59.
crystals, 29.

crystallization, origin of, 62.
Dana's division of, 60.
disintegration through ex-
ternal forces, 93.
disintegration, products of,

114.
markings, 28.
metamorphism, 83.

causes of, 89.
salt, 26, 30, 65.
solution by carbonic acid, 106.
modifying influ-
ences, 109.
water, 103.
strata, 2.

arrangement of, 2.
dislocation of, 2.
unstratified. 2.
Von Cotter's division of, 60.
Root-force of plants, 184.
Roots as rock-disintegrators, in.
chemical action of, in.
disintegrating power of, 112.
how they procure food, 203.
physical action of, in.
Running waters, 97.

deposits made by,

99.
solid matter in, 99.

S
Salt soil, 149.
Sand. 69, 121.
Sandstone. 14. 69, 12L

28o

INDEX.

Sandy soils, 148.
Sedentary soils, 146.
Serpentine, 63, 117.
Shales, 69, 122.
Silicic acid, 5. 144.
Silurian age, animal life in, 13.
close of, 13.
formation, 10.

division of, 11.
fossils, II.
minerals, 12.
rocks, II.

distribution, 12.
soils, 12.
Sinking of eastern coast of North

America, 85.
Slate, 119.
Soda, 141.

Soil:

absorption of nutritive matter,
20S.

air, composition of, 192.

as bearer and habitation of
plants, 194.

behavior toward water, 155.

capacity of absorption, 209.

capillary water of, 157.

characteristics of, 152.

classification and character-
istics, 146.

by origin, 146.
physical char-
acter, 147.

color of, 154.

composition of, 133.

variations in, 145.

compounds, 196.

conductivity of heat, 171.

constituents, 141.

electricity, uses of, 191.

estimation, 150.

evaporation, amount of, 183.

exhaustion, 213.

fertility, maintenance of, 213.

food, assimilation of. 202.

formation, factors of, 94.

Soil moisture affected by cultivation,
162.

permeability of, 157.

physical analysis of, 151.

proper concentration of nutritive
solutions, 206.

saturation of, 208.

specific gravity of, 153.
heat of, 168.

structure, 154.

temperature modified by vegeta-
tion, igo.

temperature, modifying condi-
tions of, 190.

water capacity of, 155.
solutions of, 165.

Soils:

conditions for absorbing mois-
ture, 164.
drying propenstiy of, 162.
improved by plant decomposi-
tion, 112.
loss by evaporization, 161.
origin and composition of, 123.
percentage composition of
twenty dififerent specimens,
216, 217.
primary formation of, 124.
relation to atmospheric tem-
perature, 175, 177.

plants, 195.
relative capillary attraction of,

158.
results of absorptive properties

of, 212.
temperature of, 167.

wet and dry,
169.
transported, 146.
Stone age, 55.

relics of, 55.
Sub-carboniferous age, iS.

rocks, distri-
bution of,
18.
Sub-soil, 150.

IiXDEX.

281

Superphosphates, loS.
Sulphuric acid, 144.
Syenite, 66, 118.

Talc, 63, 117.

Techtonic metamorphism, 89.

Temperature, changes of, 94.

Terraces, 57.

Tertiary age, climate of, 44.

distinguishing features,

40.
divisions of, 40.
formation, 37.

geographical
changes of, 3S.
rocks, 40.

distribution of, 41.
soils, 42.
Thermal waters, 76.
Tilth, 150.
Tin, 16.

Transition periods of earth, 3.
Triassic climate and life, 30.
formation, 27.
rocks, 27.

distribution of, 28.
soils, 30.
Tufa, 68, 120.

U

Ulmin, 133.

Valley- and basin-forming phenom-
ena, 25.

Vegetation, indispensable constitu-
ents, 205.
Vertebrates, primary, 14.
Volatile ammonia gas, 127.
Volcanoes, 42, 71.
Volcanic action, 42.

eruptions, characteristics

of, 74.
eruptions, causes of, 72-74.
results of, 75.

W
Water, action of, 95.

as a destroyer of cohesion, 96.
chemical action of, 102.
evaporation and precipita-
tion, 98.
foreign substances in, 102.
geologic changes caused by,

96.
mechanical activity of, 96.
rock disintegration by, 95.
varied action on rocks, 103.
volume and force of, 97.
Weathering. 114.

of simple crystalline

rocks, 116.
of compound crystalline

rocks, 118.
susceptibility of rocks,
115-

I Zeolites, 62, 116.

INDEX TO CHAPTER V, PART THIRD.

Analysis of plants, 223.

Capillary action, 237, 238.

tubes, 237-239.
Carolina phosphate, 225.
Chalk, 234.
Clay, 230.

Clover, habitat, westward progress,

246
Commercial fertilizers, 226.
Cotton-seed meal, 224.
Cultivation, of soil, 215.

Fallow, bare, 246.

282

Fallowing, 226.

Fertilizers, method of applying, 233

INDEX.

Plant food, when and what apply,
221.
of manure, 229.

Gravity, action on soil waters, 237.
Green manuring, 245, 246.

Humus of manure, 229.

Irrigation. 235.

artesian, 235, 236.
sub, 236.

Leguminous crops, 246.

Lime, 234.

Loam, Red River Valley, 241.

Manures, average value of, 228.

loss of, by decomposition,
230.
lack of protec-
tion, 231.
Marl, 234.

Milk, effects of selling, 244.
Mulching, 237.

Nitric acid, form of supply, 232.
Nitrogen, essential to fertility, 224.

availability of, 231.

loss by drainage, 233.

of swamp lands, 247.

Phosphates, 22r, 225.
Phosphate-rock, 225.
Phosphoric acid, 224, 225.
Plant food, 226.

balanced, 220.

Plaster, 234.

Plough, emblem of agriculture, 216.

Plough-pan, 217.

Potash, 2^7.

relative value of different

forms, 225.
essential to fertility, 224.
Production, object aimed at, 216.
Pulverization, objects of, 218.

essential to prepara-
tion for crop, 216.

Rotation, 230, 245.

Salt, action on soil waters, 241, 242.
Sand, 234.

demand of, for humus, 230.
Soil, aeration of, 219.

fineness of division of, 2iq.

exhaustion, 222.

investment, 215.

analysis, failure of, 221.
Spade, effectiveness of, 217.

Tillage, effects of, on soil, 218.
implements of, 21 S.
effects of, on evaporation,

23S.

Waters, of soil, conservation of, 238.
constant motion of,
238.

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Halsted's Elements of Geometry Svo,

" Synthetic Geometry Svo,

Johnson's Curve Tracing 12mo,

" Diffeiential Equations — Ordinary and Partial.

Suuvll Svo,

" Integral Calculus 12mo,

" " " Unabridged. Small Svo. {In press.)

" Least Squares 12mo,

*Ludlow's Logarithmic and Other Tables. (Bass.) Svo,

* " Trigonometry with Tables. (Bass.) Svo,

■•Mahan's Descriptive Geometry (Stone Cutting) Svo,

Merriman and Woodward's Higher 3Iathematlcs Svo,

Merriman's Method of Least Squares Svo,

Rice and Johnson's Differential and Integral Calculus,

2 vols, in 1, small Svo, 2 50
11

1

50

4 00

1

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1

50

1

50

1

50

1

75

1

50

1

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3

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1

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1

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2 00

8 00

1

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5 00

2 00

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1

25

1

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75

1

25

3

50

1

50

2

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1

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3 00

Rice aad Johnson's Differential Calculus Small 8vo, $3 00

" Abiidgment of Differential Calculus.

Small 8vo,

Totten's Metrology 8vo,

Warren's Descriptive Geometry 2 vols., 8vo,

' ' Drafting Instruments 12mo,

" Free-band Drawing 12mo,

'' Linear Perspective 12nio,

" Primary Geometry 12mo,

" Plane Problems lOmo,

" Problems and Theorems 8vo,

" Projection Drawing 12mo,

Wood's Co-ordinate Geometry .Svo,

" Trigonometry 12mo,

Woolf's Descriptive Geometry Large Svo,

MECHANICS-MACHINERY.

Text-books and PiiACTiCAii Works.
{See also Engineering, p. 8.)

Baldwin's Steam Heating for Buildings 12mo,

Barr's Kinematics of Machinery ^ 8vo,

Benjamin's Wrinkles and Recipes 12mo,

Chordal's Letters to Mechanics 12mo,

Church's Mechanics of Engineering 8vo,

" Notes and Examples in Mechanics 8vo,

Orehore's Mechanics of the Girder Svo,

Cromwell's Belts and Pulleys 12mo,

" Toothed Gearing 12mo,

Comptou's First Lessons in Metal Working 12nio,

Compton and De Groodt's Speed Lathe 12mo,

Dana's Elementary Mechanics 12mo,

Dingey's Machinery Pattern Making 12mo,

* Dredge's Trans. Exhibits Building, World Exposition.

Large 4to, half morocco,

Du Bois's Mechanics. Vol. L, Kinematics Svo,

Vol. IL, Statics Svo,

Vol. in. , Kinetics Svo,

Fitzgerald's Boston Machinist ]8mo,

Flather's Dynamometers 12mo,

' ' Rope Driving r3mo,

Hall's Car Lubrication ]2mo,

Holly's Saw Filing ISmo,

Johnson's Theoretical Mechanics. An Elementary Treatise.
{In the press.)

Jones's Machine Design. Part I., Kinematics 8vo, 1 50

12

2

50

2

50

2

00

2

00

6 00

O

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5

00

50

50

50

50

50

2 00

5 00

3 50

4 00

3 50

1

00

2

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2 00

1

00

75

7 50

5 00

4 00

5 00

4 00

1 50

3 00

?, eo

3 00

1 00

7 50

5 00

5 00

Jones's Machine Design. Part II. , Streugtli aud Proportion of

j\r:ichiMe Parts 8vo, |3 00

Lanza's Applied Mecbauics 8vo,

MiicCord's Kineniiitics 8vo,

:\Ierriniiin's Mecliauics of Materials 8vo,

Metcalfe's Cost of Manufactures 8vo,

*Michie's Analytical Mechanics 8vo,

Richards's Compressed Air 12mo,

Robinson's Principles of Mechanism 8vo,

Smith's Press-working of Metals 8vo,

Thurston's Friction and Lost Work 8vo,

The Animal as a Machine ■ 12mo,

Warren's Machine Construction 3 vols., 8vo,

Weisbach's Hydraulics and Hydraulic Motors. (Du Bois.)..8vo,
Mechanics of Engineering. Vol. III., Part I.,

Sec. I. (Klein.) 8^0,

Weisbach's Mechanics of Engineering. Vol. III., Part I.,

Soc.IL (Klein.) 8vo, 5 00

Weisbach's Steam Engines. (Du Bois.) 8vo, 5 00

Wood's Analytical Mechanics 8vo, 8 00

Elementary Mechanics 12mo, 1 25

<< '< " Supplement and Key 12mo, 125

METALLURGY.

Iron— Gold —Silver— Alloys, Etc.

Allen's Tables for Iron Analysis 8vo,

Egleston's Gold and Mercury Large 8vo,

Metallurgy of Silver Large 8vo,

* Kerl's Metallurgy— Copper and Iron 8vo,

* " " Steel, Fuel, etc 8vo,

Kunhardt's Ore Dressing iu Europe 8vo,

Metcalf's Steel— A Manual for Steel Users 12mo,

O'Driscoll's Treatment of Gold Ores 8vo,

Thurston's Iron aud Steel 8vo,

Alloys 8vo ,

Wilson's Cyanide Processes 12mo,

MINERALOGY AND MINING.

Mine Accidents— Ventilation— Ore Dressing, Etc.

Barringer's Minerals of Commercial Value. . ..Oblong morocco, 3 50

Beard's Ventilation of Mines 13mo, 3 50

Boyd's Resources of South Western Virginia 8vo, 3 00

" Map of South Western Virginia Pocket-book form, 2 00

Brush and Penfield's Determinative Mineralogy. New Ed. 8vo, 4 00

13

3 00

7 50

7 50

15 00

15 00

1 50

3 00

3 00

3 50

2 50

1 50

Chester's Catalogue of Miuerals 8vo. $1 25

Paper, 50

" Diftiouary of the Names of Miuerals 8vo, 3 00

Duua's American Localities of Miuerals Large 8vo, 1 00

" Descriptive Miueralogy (E. S.) Large 8vo. half uiorocco, 12 50

First Appeudix to System of Miueralogy. . . .Large 8vo, 1 00

Miueralogy and Petrography. (J. D.) 12nio, 2 00

" Miuerals aud How to Study Them. (E. S.) 12uio, 1 50

" Text-book of Miueralogy. (E. S.)... New Edition. 8vo, 4 00
*Drinker'sTwuuelling, E.xplosives, Compouuds, and Rock Drills.

4lo, half morocco, 25 00

Egleston's Catalogue of ]\[inerals aud Synonyms 8vo, 2 50

Eissler's Explosives — Nitroglycerine and Dynamite 8vo, 4 00

Hussak's Rock form uig Miuerals. (Smith.) Small 8vo, 2 00

Ihlseng's JIanual of ]\Iining 8vo, 4 00

Kuuhardt's Ore Dressing in Europe 8vo, 1 50

O'Driscoll's Treatment of Gold Ores 8vo, 2 00

* Penfield's Record of Mineral Tests Paper, 8vo, 50

Rosenbusch's Jlicroiicopical Physiography of Minerals aud

Rock-s. (Iddings.) 8vo, 5 00

Sawyer's Accidents in Mines Large 8vo, 7 00

Stockbridge's Rocks aud Soils 8vo, 2 50

*Tillman'.s Important Minerals and Rocks Svo, 2 00

Walke's Lectures on Explosives 8vo, 4 00

Williams's Lithology Svo, 3 00

Wilson's Mine Yenlilalion 12m(), 1 25

" Hyilraulic and Placer Miuing 12mo, 2 50

STEAM AND ELECTRICAL ENGINES, BOILERS, Etc.

Stationauy—ISIarine— Locomotive — Gas Engines, Etc.
{See also Engineering, p. 7.)

Baldwin's Steam Heating for Buildings 12mo, 2 50

Clerk's Gas Engine Small 8vo, 4 00

Ford'.s Ijoiler 3Iaking for Boiler Makers 18mo, 1 00

Hemenway's Indicator Practice 12mo, 2 00

Knea.sss Practice and Theory of the Injector 8vo, 1 50

MacCord's Slide Valve Svo, 2 00

Meyer's Modern Locomotive Couslrucliou 4to, 10 00

Peabody and Miller's Steam-boilers 8vo, 4 00

Peabody's Tables of Saturated Steam 8vo, 1 00

" Thcrmodymimics of the Steam Engine Svo, 5 00

Valve Gears for the Steam Engine 8vo, 2 50

Manual of the Steam-engine Indicator 12mo, 1 50

Pray's Twenty Years with the Indicator Large 8vo, 2 50

Pupin and Oslerberg's Tliermodynamics 12mo, 1 25

14

6 00

0

00

75

1

50

2

50

5

00

2

50

5 GO

5

00

o

50

4 00

Reagan's Steam and Electric Locomotives 12mo, $2 00

Ruiitgeirs Thciinoclyiiamics. (Du Bois.) 8vo, 5 00

Sinclair's Locomotive Runiiiug 12mo, 2 00

Suow's Steam-boiler Practice 8vo. 3 00

Thurston's Boiler Explosions 12mo, 1 50

" Engine and Boiler Trials 8vo, 5 00

" Manual of the Steam Engine. P:irt I., Structure

and Theory 8vo, 6 00

Manual of the Steam Engine. Part II., Design,

Construction, and Operation ■ Svo,

2 parts,

Thurston's Philosophy of the Steam Engine 12mo,

" Reflection on the Motive Power of Heat. (Caruot.)

12uio.

" Stationary Steam Engines Svo,

" Steam-boiler Construction and Operation 8vo,

Spaugler's Valve Gears 8vo,

Weisbach's Steam Engine. (Du Bois.) Svo,

"Whitham's Steam-engine Design 8vo,

"Wilson's Steam Boilers. (Flather.) 12rao,

"Wood's Thermodynamics, Heat Motors, etc 8vo,

TABLES, WEIGHTS, AND MEASURES.

For AcTi-ARiES, Chemists. Exgixeers, Mechanics— Metric
Tables. Etc.

Adriance's Laboratory Calculations 12mo, 1 25

Allen's Tables for Iron Analysis 8vo, 3 00

Bixby's Graphical Computing Tables Sheet, 25

Comptous Logarithms 12mo, 1 50

Crandall's Railway and Earthwork Tables 8vo, 1 50

Eglestou's Weights and Measures 18mo, 75

Fisher's Table of Cubic Yards Cardboard, 25

Hudson's Excavation Tables. Vol. II 8vo, 1 00

Johnson's Stadia and Earthwork Tables Svo. 1 25

Ludlow's Logarithmic and Other Tables. (Bass.) 12mo, 2 00

Totteii's Metrology Svo, 2 50

< " -..I

VENTILATION.

Steam Heating — HorsE Inspection — Mine Ventilation.

Baldwin's Steam Heating r2mo, 2 50

Beard's Ventilation of Mines 12mo, 2 50

Carpenter's Heating and Ventilating of Buildings Svo, 3 00

Gerhard's Sanitary House Inspection 12mo, 1 00

Wilson's Mine Ventilation. 12mo, 1 35

15

MISCELLANEOUS PUBLICATIONS.

Alcott's Gems, Senlimeut, Language Gilt edges, $5 00

Davis's Elenieuls of Law 8vo, 2 00

Eimnou's Geological Guide-book of the Rocky Mouutaius. .8vo, 1 50

Ferrers Treatise ou the Winds 8vo, 4 00

Haines's Addresses Delivered before the Am. Ry. Assn. ..12nio, 2 50

Motfs The Fallacy of the Present Theory of Sound. .Sq. lUmo, 1 00

Richards's Cost of Living l2mo, 1 00

Ricketts's History of Konsselaer Polytechnic Institute 8vo, 3 00

Rothcrham's The New Testament Critically Emphasized.

12mo, 1 50
" The Emphasized New Test. A new translation.

Large Svo, 2 00

Totteu's An Important Question in Metrology Svo, 2 50

* "Wiley's Yosemite, Alaska, and Yellowstone 4to, 3 00

HEBREW AND CHALDEE TEXT=BOOKS.

For Schools and Theological Seminakies.

Gesenius's Hebrew and Chaldee Lexicon to Old Testament.

(Tregelles.) Small 4to, half morocco, 5 00

Green's Elementary Hebrew Grammar 12mo, 1 25

Grammar of the Hebrew Language (New Edition). Svo, 3 00

" Hebrew Chrestomathy Svo, 2 00

Letteris's Hebrew Bible (Massoretic Notes in English).

Svo, arabesque, 2 25

MEDICAL.

Hammarsten's Physiological Chemistry. (Maudcl.) Svo, 4 00

Mott's Composition, Digestibilitj', and Nutritive Value of Food.

Large mounted chart, 1 25

Ruddiman's Incompatibilities in Prescriptions Svo, 2 00

Steel's Treatise on the Diseases of the Ox Svo, 6 00

" Treatise on the Diseases of the Dog Svo, 3 50

Woodhull's Military Hygiene 16mo, 1 50

Worcester's Small Hospitals — Establishment and Maintenance,
including Atkinson's Suggestions for Hospital Archi-
tecture 12mo, 1 25

IS

University of British Colui

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FORESTRY

AGRICULTURE

LI3RARY

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