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BOOK 630.G79 c 1

AGRICULTURE

.... .11

ELEMENTS U*5|^^

^3

SCIENTIFIC AND PRACTICAL

AGRICULTURE,

OR THE

APPLICATION OF BIOLOfeY, GEOLOGY AND CHEMISTRY TO
AGRICULTURE AND HORTICULTURE.

INTENDED AS A TEXT-BOOK FOR

FARMERS AND STUDENTS IN AGRICULTURE.

/&,r,sr/A

BY ALONZO GRAY, A. M.

Author of Elements of Chemistry, and Teacher of Chemistry and Natural History
in Phillips Academy, Andover, Mass.

ANDOVER:

ALLEN, MORRILL AND WARDWELL.

NEW YORK :

DAYTON AND NEWMAN.

1842.

^^-^

#

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

ALONZO GRAY,
in the Clerk's Office of the District Court of Massachusetts.

'•*''«^.^,«^%

PREFACE

About two years since, the author turned his attention to
Agricultural Chemistry, with a view to prepare a text-book
on scientific and practical Agriculture. His particular ob-
ject was, to furnish facilities for the introduction of Agricul-
ture, as a branch of study, into some of our academies and
high schools. This design has been steadily pursued ; al-
though, at the time of commencing his investigations, the
subject was involved in so much obscurity and uncertainty,
that he often despaired of being able to prepare a book, which
would be of any real service to those for whom it was in-
tended.

The late works of Liebig, Daubeny, Johnston and Dana,
together with the Geological Reports, in most of the States,
have thrown a flood of light over the whole subject ; and
although we cannot affirm that all is known which it is de-
sirable to know, still, many fundamental principles are estab-
lished ; and we have the materials for constructing the most
important and useful science of modern times.

The avidity with which the public mind have seized every-
thing which promised to throw light on the art of husbandry,
is an encouraging indication, that it begins to appreciate the
vast importance of the subject.

The fact, that many gentlemen of education and fortune are
resorting to this primitive art, as a means of pleasure or for
scientific purposes, still further shows, both the dignity of the
employment, and its power of aflTording those simple and

IV PREFACE.

satisfying pleasures, which cannot be derived from mercantile
or professional pursuits.

In view of such considerations, the author has been deeply
impressed with the desirableness of furnishing the young far-
mer with a scientific knowledge of his profession. This is
especially desirable, in order to give dignity and attractive-
ness to the employment. A thorough knowledge of the
fundamental principles upon which the art is based, seems
almost essential to successful practice. This necessity is
yearly becoming more and more imperative.

The States, generally, have made ample provision for the
education of their sons, in almost every branch of knowledge,
with the exception of that, upon which the profession of the
majority is based. The art on which all depend, and which
the great body of the people practice, is left without any
professional instruction, either public or private.

To supply, in some degree, this glaring deficiency in our
popular system of education, and to call the attention of those
who are interested in the prosperity of our free institutions,
to the importance of having the sons of republicans well in-
structed in this most noble art, have been the principal in-
ducements, for giving this work to the public in its present
form. For we are fully persuaded, that Agriculture will
never be held in that high estimation which it deserves to be ;
that it will never attain to that perfection of which it is sus-
ceptible ; until it is made a regular branch of study by those
who practice it as a profession ; until it is incorporated into
our systems of education.

But although this work is designed for students in Agricul-
ture ; it is not intended to be studied exclusively by those,
who are attending at some public institution. It is designed
for the farmer, at whatever stage of his education he may
have arrived ; for we believe that it is as true of farmers, as
of any other class of men, that they are "never too old to

PREFACE. V

learn ;" and that, unless they are very stupid, they generally
do learn something new every day of their lives.

It has been necessary, to introduce many terms of a tech-
nical character, but none are used which have not been de-
fined, or whose signification may not be discerned by a care-
ful examination. We trust, therefore, that the farmer will
not be deterred from reading the work, because he may find
words belonging to sciences which are unknown to him. If
he will not only read the book, but study it, and that too
in course, we venture to assure him, that he shall be able to
understand what is written, whether he is benefited by it
or not.

In the preparation of the work, the author has consulted
several writers on Agricultural' Chemistry, particularly Sir H.
Davy, Chaptal, Sinclair, Liebig, Daubeny, Johnston and Da-
na ; and also, various Reports and periodical publications.
The view^s of each writer, on many important points, have
been presented, and their theories examined.

In addition to an Index, a very full Table of Contents is add-
ed. This table is intended to contain a complete analysis of
the work, in the form of topics. The design of this table is, to
fiirnish the student with the most important subjects for his
attention ; and, should the work ever be so fortunate, as to
be introduced as a text-book into cur academies, these topics
may serve the purpose of direct questions.

It is proper, in this place, for the author to acknowledge
his particular obligations to Dr. Samuel L. Dana of Lowell,
for the many kind suggestions which he has made from
time to time, and for the important aid afforded by his late
work ; although not received, until nearly the whole of this
work was prepared for the press.

The author would also express his obligations to the Trus-
tees of Phillips Academy, who have so promptly responded to
the suggestion of preparing a text-book for the use of the In-
1*

Vi PREFACE.

stitution under their care; and who have afforded him many
facilities for bringing the work to a close at so early a date.

With the hope that this effort to improve our system of
rural economy will meet with that success which is so ear-
nestly desired, the author would now commit these results
of his studies to the better judgment of those who may be
induced to read what is herein written.

A. G.

Encr. Depart, in Phillips Academy, )
* Andover, April, 1842. >

TABLE OF CONTENTS.

INTRODUCTION.

Page.
Agriculture defined — its importance 17

Aid which it may derive from the Natural sciences . . .18

I. Mineralogy and Geology 18

II. Chemistry 19

III. Botany 24

Plan of the Work ■ 25

Influence of slight improvements 26

BIOLOGY OF PLANTS.

CHAPTER I.— The Vital Principle,
Division of Natural bodies 29

Sect. 1. Definitions and descriptions — proofs^ nature and uses of the
Vital Principle.

Definition of Biology 29

Of an organized body 30

Definition of a plant 30

Tissue defined and described 30

Cells 30

Spiral vessels — Pores — Cuticle — Wood . • . . . 31
Cambium, Alburnum, Assimilation, Transpiration . . .38

Comparison of the Vital Principle in animals and plants . . 33
Proofs of the existence of Vitality.

I. Power of vegetables to resist natural laws — 1. Chemical affini-
ty. 2. Gravity. 3. Heat and Cold 35

II. Excitability in vegetables. — 1. Influence of light. 2. Of heat 36
3. Of electricity. 4. Of artificial stimulants . . . .37

III. Irritability of vegetables ....... 37

IV. Productions of the vegetable kingdom . . . .37

JVature of Vitality — Biological hypotheses 38

Definition of life 39

Vm CONTENTS.

Uses of the vital principle 40

1. J'^3 relations to agriculture as a science . . . . .40

2. Its relations to Natural Tlicology 41

3. Moral effect of considering this power 43

Sect. 2. Definitions. — Conditions necessary to develope the Vital
Prmciple in the seed, bulb and bud.

Definitions — 1. Of eeed 43

,2. Of cotyledons. 3. Radicle. 4. Plumala. 5. Bulbs. 6. Buds 44
7. Eyes. 8. Chemical transformations — catalytic force. 9. Of

a simple substance ........ 45

10. Of Compound bodies. 11. Of alkalies and acids. 12. Of

salts. 13. Of equivalents. 14. Organic constituents . 46

15. Inorganic constituents. ...,.:. 47

Organic Constituents — 1. Oxygen 47

2. Hydrogen — water 47

3. Carbon, carbonic acid 48

4. Nitrogen, nitric acid, ammonia 48

Germination — Conditions of ....... 49

1. Moisture — its influence upon germination . . . .49

2. Air " « 50

3. Heat « ".-... 51

4. Light " " 52

Changes during the process of germination . . . .53

Methods of promoting germination.

1. By immersing the seeds in hot water . . . .54

2. Experiments by Mr. Bowie . . . . . .54

3. By mixing seeds with substances which yield oxygen easily 55
Object of all the vegetable functions — propagation; effected by

seeds, buds, bulbs and leaves ....... 55

By cuttings, layers and suckers 56

Theory of the formation of the different organs of plants . 57

Sect. 3. Definitions — Conditions of the growth of plants.

Definition 1. Of soil 57

2. Of sub-soil 58

Organs of nutrition — 1. Roots, different kinds of . . .58

2. Stem or culm — its functions 58

3. Leaves, their structure and office 59

4. Flower leaves or petals — their office — analogy between ani-

mal and vegetable bodies 60

CONTENTS.

IX

Conditions of growth.

I. Proper medium and space for growth . . . . .61
Uses of the soil — 1. Support 61

2. Repository of food. 3. Chemical changes, medium of . 61

4. Medium for air, water and heat . . . . .62

5. Absorption of gases ........ 62

II. Food. Supply of food.

1. Constancy of supply 63

2. Proper regulation ........ 63

Practical inferences 64

3. Kind of food — nature of 65

III. Tillage — Conditions of 66

1. Thorough ploughing ........ 66

2. Deep ploughing, importance of . . . . . .67

3. Pulverizing the soil 68

4. Covering the seed ........ 68

.5. Extermination of weeds ....... 69

Importance of the above conditions illustrated . . . .70

CHAPTER II.

INFLUENCE OF THE ATMOSPHEKE, WATER AND OTHER AGENTS, UPON
THE VITAL PRINCIPLE, AS CONNECTED WITH THE PHENOMENA OF
VEGETATION.

Sect. 1. JJgejicy of the atmosphere.
Composition of the atmosphere ....
I. Influence of the oxygen of the air upon the roots

Theories

Influence of oxygen upon the leaves of plants .

Theories

Quantity of oxygen absorbed by plants, dependent,

1. Upon their vigor

2. Upon temperature

3. Upon the season of the year
Quantity absorbed by the fleshy-leaved plants

" " evergreens

" " herbaceous plants

" " trees naked during the winter

Action of oxygen upon fruit ....

Summary of the agency of oxygen
II. Influence of the nitrogen of the air

72

73
73

75
76

76
76
76
76

77
77
77
78
79
80

X CONTENTS.

III. Influence of the ammonia of the atmosphere . . .80
Sources of ammonia.

1. Putrefaction of animal bodies . . , . , .81

2. Decay of vegetable substances ...... 81

3. Volcanoes 81

IV. Nitric acid of the atmosphere 82

V. Light carbureted hydrogen 83

VI. Influence of the carbonic acid of the atmosphere . . 83
Source of carbovic acid.

1. Chemical action 84

2. Combustion 84

3. Respiration of animals ■ . 84

4. Decay of vegetables 84

Quantity of carbonic acid in the atmosphere . . . .84
"W%at becomes of this acid ? 85

1. It is decomposed by vegetation . . . . .85

2. Quantity of this acid absorbed at different periods . . 8G
Other causes which abstract it . . . , . . .88
Necessity of carbonic acid to vegetation . . . . .88

VII. Mechanical agency of the atmosphere.

1. Pressure 87

2. Medium for the action of other agents . . . .90
Beautiful and wise constitution of the atmosphere . . .91

Sect. 2. Agency of water upon the vital functions of plants.

I. Water in the solid form — ice and snow 02

1. Benefits of freezing the soil 92

2. Protection afforded the roots by ice and snow . . .92

II. "Water in the liquid form.

1. Its solvent properties ....... 93

2. Its chemical agency 94

3. Its mechanical agency 95

4. Its agency as nutriment 95

III. Water in the state of vapor.

1. Quantity of vapor in the atmosphere . . . .96

2. Absorption by the leaves and roots , . . . .96

3. Influence in dry seasons ....... 97

4. Agency of dew as affected by the conducting power . 97

5. Agency of rain ......... 97

6. Effect of evaporation upon soil ... .98

CONTENTS.

Sect. 3. Influence of the imponderable agents upon the vital func-
tions of plants.

I. Gravity. Experiments of Mr. Knight 98

II. Cohesion 99

III. Chemical affinity 100

IV'. Caloric. — Properties necessary to be studied • . 101

1. Its influence on affinity 102

2. Effect of heat in the spring — of too great heat . . 102

3. Tendency of heat to pass into an insensible state . .102

4. Effect of heat during the winter 103

Distribution of plants dependent upon temperature . . 104

V. Light. Calorific. Colorific and chemical rays . . 105

1. Stimulating properties of light 105

2. Its power in the decomposition of carbonic acid by the leaves 106

3. Different colors. Experiments of Mr. Hunt . . . 106

VI. Electricity. Modes of exciting it. Theory . . . 107

Endosmometer, description of 108

Cause of the ascension of the sap ...... 109

Sect. 4. Agency of man.
Methods by which men may control the imponderable agents 111

CHAPTER 111.

PRODUCTIONS OF THE VITAL PRINCIPLE — THEIR CHARACTER, COMPO-
SITION, SOURCES AND ASSIMILATION,

Sect. 1. Character and comjiosition of the vegetable productions.

I. Acids 117

II. Alkalies . . . 119

III. Intermediate bodies . . 120

IV. Neutral substances 123

1. Sugars. 2. Amylaceous substances .... 124

3. Gums 125

4. Glutinous substances 126

Sources of many articles of food and medicine .... 126

I. Roots 128

II. JBulbs 129

III. Woods 130

IV. Leaves 130

V. Seeds and fruits 131

XU CONTENTS.

Sect. 2. Definitions and descriptions . — Source and assimilation
of the organic constituents of jtlants.

Definition and description — ]. Of huniin , . . . 135

2. Of humic acid. 3. Of crenic acid. 4. Of apocrenic acid 136

5. Of apocrenates. 6. Extract of humus .... 137

Source of organic constituents.

I. Carbon. History. Nature of vegetable mould . , 138

Theories

I. Of Liehig. Arguments in support of Liebig's theory , 140

1. Quantity of carbon introduced in the form of humate of lime 141

2. '< " by metallic oxides . . 141

3. " " by water .... 141

4. Quantity of carbon yielded by wood land, meadows and

ploughed fields 142

Origin of the carbon of the first vegetables .... 142

Quantity in the atmosphere invariable. Why ? . . . 143

How is the carbonic acid of the atmosphere disposed of.? . 143

5. The most important function in the life of plants— what ? 144

6. Nature of decay— changes which take place . . . 144

7. Excrementitious matters of the roots 145

Objections to Liebig's theory.

1. This theory does not give acorrect view of the humus of soil 146

2. The facts which are brought forward do not prove it,

allowing them their full force 146

3. This theory does not give a correct view of the quantity

of water in the soil 147

4. This theory overlooks the influence of living plants . 147

5. There are evidently other sources of carbon . . .148

6. The theory is inconsistent with itself and with facts . 148

7. " " must therefore be modified . . . .149
Other sources of carbon, humic, crenic and apocrenic acids , 150
Summary of the sources of carbon 151

TIteory of the assimilation of carbon
Illustrated by chemical transformations . . . .151

Chemical transformations in plants and animals . . . 153

II. Source of the hydrogen of plants.

1. Water. 2. Ammonia. 3. Light carbureted hydrogen . 155

4. Geine or humus 155

ni. Sources of the oxygen of plants.

1. The atmosphere. 2. Water 155

3. Carbonic acid. 4. Geine or humus. 5. Nitric acid . 156

CONTENTS.

XUI

IV. Theory of the assimilation of oxygen and of hydrogen . 156

V. Source and assimilation of the nitrogen of plants . . 158
1. The atmosphere. 2. Ammonia. Proofs . . . 159
Quantity of nitrogen derived from ammonia .... 161
Objections to Liebig's theory of the source of nitrogen . . 162
Form in which ammonia enters plants 163

3. Geine or humus ........ .163

4. Nitric acid, in the form of nitrates 164

Necessity of supplying plants with humus .... 165

Sect. 3. Definitions. — Source and assimilation of the inorganic
constituents of plants.

Description of potassa, soda, magnesia and other salts . . 166

" " lime, alumina, oxide of iron and silicic acid . 167

" " hydrochloric, sulphuric and phosphoric acids 168

Inorganic constituents.

1. Potassa, source and assimilation 171

2. Soda, ^^ « « 173

3. Magnesia, " " " 174

4. Lime, u u a 174

5. Alumina, " " " ...... 175

6. Silica. 7. Metallic oxides 175

8. Phosphoric acid. 9. Sulphuric acid. 10. Common salt 176

GEOLOGY AND CHEMISTRY OF SOILS.
CHAPTER IV.

ROCKS AND THEIR RELATION TO VEGETATION.

Sect. 1. Simple bodies which compose the rocks.

Sect. 2. Compounds formed by the fourteen simple bodies

I. Primary compounds, or bodies composed of two simple bodies
1. Acids. 2. Alkalies. 3. Urets

II. Secondary compounds or salts

1. Silicates

2. Carbonates of soda, magnesia and potassa

3. Sulphates. 4. Nitrates ....
5. Phosphates. 6. Muriates

B

180
181
181
181

182
182
183

XIV CONTENTS.

Sect. 3. Simple jninerals which enter into the composition of the

rocks.

1. Quartz 183

2. Feldspar. 3, Mica. 4. Talc 184

5. Hornblende. 6. Serpentine. 7. Calcareous spar . . 185
8. Pyrites (fool's gold) .186

Sect. 4. Composition of the rocks

1. Igneous and aqueous rocks 187

Igneous rocks. 1. Granite. 2. Gneiss. 3. Mica slate . . 187

4. Argillaceous slate. 5. Talcose slate. G. Hornblende slate 188
7. Graywacke. 8. Trappean rocks. 9. Limestone rocks . 188
10. Sandstones 188

Sect. 5. Origin of soils.
Agents concerned in wearing down the rocks . . . • 188
1. Oxygen. 2. Pyrites 189

3. Mechanical agency of water. 4. Decaying plants . .190

5. Growing plants 191

Depth of soil 192

CHAPTER V.

SOILS, AND THEIR RELATIONS TO VEGETATION.

Sect. 1. .Analysis of soil.

I. Mechanical analysis and tests 195

II. Chemical analysis of soils . . ..... 198

Rules of analysis by Dr. Dana 198

« " Dr. Jackson 198

Sect. 2. Composition of soils as determined hy analysis.

1. Mineral constituents of soil 205

1. Earths.

(1) Silicic acid, its quantity and of5ces .... 205

(2) Aluminous earth, "^ " 206

(3) Lime, « " 207

(4) Magnesia, " '< 209

2. .Alkalies and metallic oxides. Ammonia . . , .210

Potassa, quantity and uses, 211

Soda and oxide of iron, " ^ . 212

3. Salts and urets. Common salt 213

CONTENTS. XV

Phosphate of alumina and of lime 214

JNitrate of potash and of soda. Sulphurets .... 214

II. Organic constitxicnts of the soil. Humic acid. Geine . 215

Crenic and apocrenic acid. Extract of humus and humin . 216

Sect. 3. Theory of the mutual action of the organic and inorganic
constituents of soil, and of groimng vegetables.

1. Action of the organic and inorganic portions of soil . . 218

1. Of silicates. 2. Carbonates. 3. Alkalies. 4. Catalysis 219

5. Air and water 219

n. Mutual action of growing plants, silicates, salts, etc. . . 219

1. General theory of the action of salts .... 220

2. Character of the acid determines the peculiarity of effect 220

Sect. 4. Circumstances upon which the fertility of soil depends.

General inferences 228

Sect. 5. Classification and description of soils.
Geological classification of soils.

I. Alluvial soils. 1. Of rivers 231

Value of alluviarsoils. 2. Peat alluvial soils . . . 232

II. Diluvial soils. 1. Sandy and gravelly .... 233
2. Argillaceous, clayey and loamy 234

III. Tertiary soils. Their origin and character . . . 2*34

IV. Secondary soils. 1. Cretaceous or chalky soil . . 235

2. Oolitic soil. 3. Saliferous. 4. Carboniferous. 5. Silurian 236

V. Primary soils 237

1. Argillaceous slate soil. 2. Limestone soil . . . 238

3. Mica slate soil. 4. Talcose slate soil .... 239
5. Gneiss soil. 6. Granite soil. 7. Sienile soil . . 240
8. Hornblende rock soil. 9. Porphyry soil .... 241

VI. Trappean soils. 1. Greenstone. 2. Trachyte. 3. Lava
soils 241

Chemical classification of soils.

1. Siliceous soils. Properties and mode of improvement . 243

2. Aluminous or clay soils — their properties .... 244

3. Calcareous soils. Properties and tests .... 246

4. Magnesian soils ......... 247

5. Peaty soils. Origin of. Properties, etc. . . . . 247

6. Alluvial soils. 7. Loamy soils . . ..... 249

XVI CONTENTS.

CHAPTER VI.

IMPROVEMENT OF THE SOIL.

Sect. 1 . Improvement of the soil by the addition of earths.
1. By carbonate of lime. 2. By sand and gravel . . . 253
3. By clay. Theory of the action of clay .... 253

Sect. 2. Improvement of the soil by draining and irrigation — Causes
of wetness.

I. Draining. 1. The surface. 2. Draining the soil . . 256

Construction of drains. Metiiod of 257

3. Draining the sub-soil 258

Necessity of draining 260

Utility of draining 262

II. Irrigation — time and mode of watering .... 262

Sect. 3. Improvement of the soil by fallow crops and by turning in
green crops.

I. Fallow crops. Naked fallows defined .... 265
Utility of fallow crops 266

II. Turning in green crops. Process ..... 267
Theory of the action of green crops 268

Sect 4. Rotation or interchange of crops.
Rotation founded on experience ...... 270

Reasons for an interchange of crops.

I. The structure of plants 271

1. Culmiferous plants. Their influence in this respect . 272

2. Leguminous plants. 3. Root crops .... 273

II. Composition of plants 273

III. Excretions given out by the roots ..... 276
Theory of M. Decandolle. Of Macaire Priueep . . . 276
Rules for constructing a rotation system . . . . 278

Sect. 5. Root culture — Theory of their action.
CHAPTER VII.

IMPROVEMENT OF THE SOIL BV MANURES AND TILLAGE.

Sect. 1 . Mixed manures., or those consisting mostly ofgeine.
I. Solid excrements of animals. 1. Cow dung, analysis of . 284

CONTENTS. XTU

Value of COW dung 285

2. Plorse manure, analysis of ...... 286

3. Sheep dung. 4. Hog manure. 5. Night soil . . 287
Changes in fermenting dung heaps ..... 288
C. Poudrette. 7. Guano, analysis of . . . . . 293
8. Pigeons' dung and that of domestic fowls . . . 297

II. Animal solids — their composition ..... 294
1. Horns and hoofs. 2. Nails. 3. Hair . , . .295

4. Wool. 5. Feathers. 6. Glue. 7. Bones, bone dust and

soot 296

HI. Animal and vegetable bodies destitute of nitrogen . . 297
1. Soap-boilers' spent lye, composition and use . . . 298

Sect. 2. Manures consisting of animal salts.

1. Urine of the cow, composition and value .... 300

2. Urine of the horse " " .... 300

3. Human urine ......... 300

Sect. 3. Manures composed mostly of geine.

I. Sea weed. — 1. Ribbon weed. 2. Carrageen moss. 3. Rock
weed. 4. Eel grass. 5. Sea coral. Preparation and applica-
tion of sea weed ......... 303

II. Peat, swamp muck and pond mud, their comparative value 306

1. Peat composted with alkalies 306

2. Peat composted with animal matter .... 308

3. Peat composted with green manures .... 309

Sect. 4. Methods of applying manures.
1. For cold stiff soils. 2. For light sandy soils . . . 311
3. Action of green manures on hoed crops and grain crops 311

Sect. 5, Saline manures^ or those consisting of inorganic salts.

I. Salts whose acid contains the elements which nourish plants 312

1. Nitrates, theory of their action 313

2, Phosphates. 3. Carbonates, theory of their action . 314

Theory of the action of lime 315

Utility of lime in agriculture 317

Action of ashes, their composition 317

Peat ashes, leached ashes, white-ash 318

II. Salts whose acid does not enter into the composition of
plants, and whose action is poisonous 319

XVlll CONTENTS.

1. Sulphate of lime, utility of copperas .... 319

2. Chlorites — common salt, spent lye 319

Rules for the application of saline manures .... 320

Sect. 6. Improvement of the soil by tillage.

Utility of the roller 322

Utility of the cultivator. Importance of tillage . . . 323

CHAPTER VIII.

PRACTICAL AGRICULTURE.

Sect. 1. Cultivation of grains.

1. Indian corn . . . 324

2. Wheat, mode of culture 327

Diseases and enemies of u'heat.

1. Rust described, remedy for 32S

2. Mildew or blight, remedy for 329

3. Smut— remedy 329

4. Wire-worm. 5. Hessian fly. G. Grain insect . . 329
Cultivation of rye — value of this crop 330

« oats " 331

« barley " 332

« buckwheat « 333

Sect. 2. — Cultivation of roots.
Potato — method of selecting seed
Beets — Mangel Wurtzel. Drill-barrow .

Turnip and blood-beet — value of the crop
Parsnip. Artichoke. Onion. Turnips .
1. Rutabaga — mode of culture, value

333
335
336
337

338

2. White turnip. 3. Yellow turnip. Table of Value . 338

Sect. 3. Cultivation of grasses.

1. Clovers. — 1. Red-top, cultivation of 341

2. Cow grass or Southern clover 342

3. White clover. 4. Lucerne or French clover . . . 343

5, Timothy 344

6. Red-top. 7. Orchard grass. 8. Tall oat grass . . 345
9. Sweet-scented vernal grass. 10. Rye grass . . . 346

Relation of farm stock to the cultivated crops.

CONTENTS. XIX

CHAI^TER IX.

HORTICULTURE.

Sect. 1. Selection of seeds ^ propagation and improvement of races.

I. Maturation of seed 350

Causes of sterility 350

II. Preservation of races or varieties 352

III. Improvement of varieties and races 354

Sect. 2. Propagaiion by eyes, cuttings^ grafting and budding.

I. Propagation by eyes and buds 355

II. " cuttings and slips 355

III. " grafting and budding 356

Operations of grafting.

1. Whip grafting 357

2. Crown grafting ........ 358

3. Saddle grafting 358

4. Budding — illustration of 359

Sect. 3. Pruning, Training, Potting and Transplanting.

I. Pruning — process, use and effects of 359

II. Training — process and use of- 362

III. Potting — process, conditions of 363

IV. Transplanting— best method 363

ERRATA.

Page 68 — (4) instead of " the soil " read " the seed."
" 92 — 1. 4th line, for " appertures " read "apertures."
" 139 — margin, for " Johnson " read " Johnston,"
" 149 — for paragraph " 6." read "7."
" 159 — margin, for " Johnson " read " Johnston."
" 168 — 5th paragraph, for " /syraorp/ttsm " read ^'' Isomorphism.'*
" 184 — 2. 2d line, for "lamella" and "granula" read "lamel-
lar " and " granular."
« 276— Hi. 7th line, for " De Condolle " read " De Candolle."
" 277 — 2d paragraph, 1st line, for '^ Macaire Princeps " read

" Macaire Princep."
" 296 — C. 1st line, leave out the words '^ jelly, etc."
" 303 — 2. 1st line, for '^ Curagreen moss" read '•'■ Carrageen

INTRODUCTION.

Agriculture is the art of cultivating the soil. It includes
aJl those processes which are requisite for the cultivation of
the various grasses, graihs and fruits. The rearing and
fattening of animals, and the preservation and use of their
productions, are generally connected with it.

Agriculture may also be regarded as a science; in which
sense, it explains the reasons for these processes, or gives
rules derived from experience for the performance of each
operation of the art. As a science, it is of recent date, and
like all new sciences many of its principles are not yet 'fully
settled. As an art, it is the oldest, the mother of all other
arts, having been practised by the first parents and founders
of the race.

Agriculture must be regarded as the most important art
whether we take into view the number of men it has always
employed, the quantity and value of its productions or the
character of the influence which it exerts upon society.

The majority of men are farmers, and farmers constitute
the bone and sinew of the state. But if we take simply the
quantity and value of the agricultural productions, we shall
find that agriculture is the greatest pecuniary interest of
every country.

In England and Wales, according toMcCulloch, the quan-
tity of wheat is not less than 12,350,000 quarters, worth
31,000,000/. sterling; of oats and beans, 13,500,000 quarters
worth 17,500,000/. sterlmg ; to which may be added the
value of the grass lands, worth 60,000,000/. sterling.

According to the agricultural returns for 1839, the quan-

18 ♦introduction.

tity of wheat in the United States is 91,642,957 bushels an-
nually, worth, at one dollar per bushel, $91,642,957; of
other grains, oats, rye, corn, etc. 550,299,557 bushels, worth
upon an average at least fifty cents per bushel, which would
amount to S275, 149,778 ; of potatoes, 113,183,619 bushels,
worth, at twenty cents per bushel, $^22,6^.6,'/ 23, giving a to-
tal value of cultivated crops of 8389,429,459. But this is
but a small part of all the productions. The whole agricul-
tural produce of the country, including the domestic animals,
must be worth more than twice this amount. A late writer
has estimated the total value of the products of the country
including manufiictures, at 1200 millions of dollars annually;
the manufactured products being less than 200 millions.
'' There is no profession," says Liebig, " which can be com-
pared in importance with that of agriculture, for to it belongs
the production of food for man and animals ; on it depends
the welfare and development of the whole human species,
the riches of states and all commerce. There is no other
profession, in which the application of correct principles is
productive of more beneficial effects, or is of greater and more
decided influence." Compared then with this interest, all
others are of minor importance.

Such is the incalculable interest involved in the art, that it
becomes a question of primary importance, what aid it may
derive from the physical sciences.

It can be shown I think, in very few words, that botany,
chemistry, mineralogy and geology, furnish us with many
principles which may be applied to this art to render it more
perfect, and more productive. The laws of nature are con-
stant and unchanging in their action. If we can learn what
these laws are, as they stand related to the vegetable kingdom,
we may receive important aid from being able to control
them, or to bring our efforts to coincide with their agency.

I. Mineralogy and Geolo(jy afford aid to agriculture
chiefly by enabling us to determine, by the inspection of the

INTRODUCTION. . 19

rocks and simple minerals, the character of the soil. As all
soils originate from the decay of rocks, if we know what rocks
are crumbled into soil we may determine with some degree
of probability its character, and what agencies are at work to
benefit or injure the expected crop. If by a simple inspection
of the mineral ingredients of a soil, we may determine what
crop will best flourish upon it, we certainly must regard the
aid not only seasonable, by preventing us from expensive ex-
periments, but also highly valuable, by enabling us to obtain
a greater quantity of productions. So great is the aid which
geology renders to agriculture, that one branch of it, the origin
and descriptions of soils, is called by one writer (Hitchcock),
"Agricultural Geology." Geology further aids agriculture
by pointing out the location of useful manures, such as veg-
getable matters, lime and plaster.

II. Chemistry offers greater aid by far, to agriculture
than any other science, because it explains those changes
which must take place in the vegetable organs, and in the
soil, by which the processes of vegetation are carried forward ;
that is, chemistry supplies the greater number of the condi-
tions and agencies which are requisite to the highest activity
of the vital functions of plants, and hence teaches us how to
obtain, with the least expense, both the largest quantity, and
the best quality, of products. So great is its importance,
and so far does it exceed all other branches of knowledge, in
its relation to agriculture, that the terms '' Agricultural
Chemistry" (Davy), " Chemistry of Agriculture" (Liebig),
"Chemistry applied to Agriculture" (Chaptal), have been
employed as titles of the most important works, in which at-
tempts have been made to apply the principles of science to
this art.

It may be necessary, however, to point out, in a general
way, some of the specific forms in which this science may be
useful to agriculture, both for the sake of illustrating the gen-
eral nature of the subject, and its importance to the farmer. •

20

INTRODUCTION.

The influence which chemistry exerts may be seen by means
of the chemical forces which are acting both upon dead and liv-
ing matter. The principal agents, by which chemistry produ-
ces its beneficial results, are affinity, heat, light and electricity.

1. Chemical Affinity. This is the great agent or cause of
all chemical changes on the surface of the earth. It is an at-
traction which one kind of matter has for matter of an oppo-
site kind. In this respect, it differs from cohesion which acts
between matter of the same kind, as between two smooth pie-
ces of lead, and it differs from gravitation, which cnly acts upon
matter in masses, while affinity effects changes within imper-
ceptible distances. It tends to draw together different kinds
of matter, and to continue the compound until some force acts
upon it to produce decomposition. This force may be heat,
light or electricity, but generally it is affinity itself ; for the
most important law of its action is, that one kind of matter
does not manifest the same desire to unite with every other kind
indiscriminately, but the force of affinity is different between
different bodies ; so that when two simple bodies are unhed
by its force, some third body may have a stronger attraction
for each of the constituents, or for one of them, than they have
for each other, and the consequence will be that the compound
will be decomposed ; the third body will unite with one con-
stituent of the compound, and form a new and different sub-
stance. Thus, for example, the well known substance ro/>
peras, is found in some soils ; it is composed of sulphuric acid
(oil of vitriol) , and oxide of iron (iron 7mbt), and these two
bodies are held together by the force of affinity ; but when
carbonate of lime, common limestone, is scattered over such a
soil the copperas is decomposed, the sulphuric acid leaves the
oxide of iron, being drawn away by its stronger affinity for
lime, and sulphate of lime is formed, which is commonly
called gypsum or plaster of Paris.

In consequence of this election of one body in preference
,^ to another, the composition and decomposition of bodies are

INTRODUCTION. 21

rapidly effected. In some cases two compounds are mutually
decomposed, and two new compounds formed ; hence, as the
force of these affinities is well known, we may calculate their
influence in the soil, and to some extent in the organs of
plants. We have only to ascertain of what the soil is compo-
sed, to know what changes are going forward in it, and what
decompositions and recompositions will take place, when
we add earths, salts and manures to it ; and hence we are
furnished with the means of producing any effect that we
wish, and of securing the action of the proper agents upon
the expected crop.

But to show further the agency of affinity, it will be neces-
sary to notice some of the laws which govern it, and the other
agents which modify its action.

When bodies combine by the force of affinity, they do
not generally unite in any and every quantity or proportion,
but are governed by strict laws, that is, definite quantities of
each are required to complete their union ; thus water is
formed by the union of 1 part by weight of hydrogen and
8 parts of oxygen ; so carbonic acid (or Jized air) is composed
of exactly 6.12 parts by weight of carbon and 16 parts of oxy-
gen, and if the proportions of these substances are changed,
some other substances will be formed, but neither water nor
carbonic acid. Similar laws are observed when bodies com-
bine by volume or measure, and these laws extend to the
greater number of compounds both organic and inorganic ;
hence, as these quantities are all determined (the smallest in
which any body combines being called its equivalent or pro-
portional), we may not only explain changes in the process
of vegetation, and deduce important laws which tend to satis-
fy the mind in its investigations, but, in a more practical way,
we can determine the quantities of different substances which
any particular soil may require, especially when one saline
compound is substituted for another. Thus, for example,
when salts of ammonia are applied to the soil for the purpose
2*

32 INTRODUCTION.

of obtaining the influence of the ammonia, 100 lbs. of the car-
bonate yields an amount of ammonia equal to 146 lbs. of the
sulphate. This result has been found out by long experience,
but a knowledge of chemical proportions would have pre-
dicted it.

When substances thus combine in definite proportions,
the compounds, generally, bear no analogy to either of the
constituents. The new substances formed are in the posses-
sion of properties entirely new, and which could not have
been predicted previous to experiment ; hence two simple
bodies by combining in different proportions form entirely
different and distinct bodies, as different as common air,
the exhilarating gas, and nitric acid (aquafortis), which are
compounds of oxygen and nitrogen ; hence it is, that the al-
most infinite variety of vegetable productions are formed by
the different combinations of a few simple substances. If,
therefore, we wish to produce a greater quantity of any
given production, we must supply the conditions which will
cause such combinations to take place. Thus, for example,
where soils are destitute of animal manures, from which the
nitrogen may be procured necessary to form gluten and vege-
table albumen in wheat, an addition of nitrate of potash, soda
or ammonia, will increase the amount of these substances, and
render the grain much more valuable ; an addition of 2^ per
cent, of gluten has been thus produced in the same weight of
wheat, which would add more than 10 per cent, to its value.

In consequence of the fact, that each substance has a
definite and fixed character, we are enabled, by the aid of
afl[inity, to decompose soils, and to compare with them the
vegetable products ; hence we can not only learn the rea-
son of fertility or barrenness, but also how to remedy de-
fects, and thus point out to the practical agriculturist the pro-
cess which will secure a bountiful crop. If an analysis of
the soil be made before and after the crop, we may determine
what the effect of any substance is upon it. By the aid of

INTRODUCTION.

affinity we may also analyze the vegetable productions, and
learn what ingredients each species of plant requires for its
most perfect growth.

The quality of the productions themselves is also indicated
in these processes, for it is found that the same quantities of
wheat will not always make the same quantity of bread. The
conditions therefore on which these differences depend, we
may learn from an accurate knowledge, and application of
chemical principles.

Another point, of great interest to the agriculturist, is the
theory of the action of manures, and it is to chemistry
that he must look for the most important histructions on this
subject. A knowledge of the action of saline compounds,
and of alkalies, is all-important to the farmer. A continued
course of cropping removes them from the soil, and the cheap-
est and most effectual means of restoring them is a matter of the
first necessity to a perfect system of tillage.

And finally, " the source of the failure of crops when plant-
ed on the same soil for several successive years," is a subject
to be investigated, and its facts explained by chemical prin-
ciples. This will afford an explanation of rotation of crops,
and point out many important practical rules in regard to this
subject.

In these, and numerous other ways, which we have not time
to specify, chemistry may afford important aid to agriculture.
The other chemical forces, such as heat, light and electricity,
not only modify the action of affinity, but act directly upon
the vital functions of plants.

2. Caloric or Heat exerts an agency scarcely less impor-
tant than affinity itself. It also acts according to fixed
laws, which are known. The application of these laws to
agriculture, still further illustrates the utility of chemical sci-
ence, and is too obvious to need further specification in this
connection.

3. Light is absolutely essential to vegetation, but its influ-

24 INTRODUCTION.

ence is not so immediately under the control of the agricul-
turist as any of the preceding agents.

4. Elcctricitij even more readily yields its agency to the
skill of man. The electrical character of the soil may readily
be determined. It may even be changed by artificial appli-
ances, and hence what was barren and worthless, may be
rendered fruitful. But as these latter forces will receive par-
ticular attention, as to their influence on vegetation, in the
body of this work, it is unnecessary to enter into any further
specification of their agency.

The chemical forces above enumerated, in their influence
upon vegetables themselves, are in subordination to another
force, the living power ; and hence we must resort to
vegetable physiology {or further aid, in explaining the pro-
cesses of vegetation, and in pointing out the conditions for
successful practice in agriculture.

III. Botany furnishes us with principles more directly ap-
plicable to agriculture, as a science, than either of the preced-
ing sciences. In fact, one branch of this science, the living
functions of plants, or Biology, including the conditions of
life, and all the near or remote influences which act upon the
vital forces, and tend to quicken or destroy them, constitutes
of itself the whole science of agriculture. Such a view, how-
ever, might properly bring in chemistry, as a modifying force,
as well as mineralogy and geology. In a more restricted
sense, botany offers the following aids :

1. It explains the structure of the various organs of plants,
by which we are made acquainted with the means of introduc-
ing and disposing of the matter by which they are nourished.

3. It determines the habits of each species of plant, by
which we are enabled to adapt the crop to the climate and soil.

3. It points out what plants require as the condition of
their most perfect growth, and how to obtain the best quality
of their products. It enables us also to obtain the best kinds
or species of plants, to ascertain their mode of propagation.

INTRODUCTION. 25

their preservation and use, with the diseases which attack
them.

Plan of the Work.

I. In accordance with the above views, the first three
chapters are devoted to the conditions of the life of plants, un-
der the general head o^ Biology, including all the agents that
influence the processes of vegetation, the character, composi-
tion, source and assimilation of the vegetable principles.

II. The next four chapters are devoted to the composition
of the rocks ; origin and classification, composition and im-
provement of soils; with the theories of the action of ma-
nures, rotation of crops, fallow crops, and practical sugges-
tions.

III. The closing chapter explains the processes of Horticul-
ture, with the application of those principles which are par-
ticularly connected with this important branch of agriculture.

The object of the work, then, generally, is to explain the
phenomena of vegetation, and to deduce practical rules for
the benefit of the practical farmer ; in order to render the
modes of tillage more precise and rational, and thus to afford
a stimulus to intellectual and moral improvement, by making
farmers more scientific men ; and in order to increase the
amount of agricultural productions, by rendering the earth
more fertile, and the processes of cultivation easier and more
successful.

If by the application of the principles contained in this
work, these results are attained, in but a slight degree, it is
all that I can hope. I will therefore conclude these intro-
ductory observations by a calculation of the value of any
slight improvement in this most useful art.

In England, " the average produce of wheat," says Mr. Pu-
sey, " is stated at 26 bushels per acre ; if by a better selection
of seed we could raise this amount to 27 bushels only, (a sup-
position by no means unlikely), we should by this apparently

26 INTRODUCTION.

small improvement have added to the nation's annual income
475,000 quarters of wheat, worth, at fifty shillings, about
1,200,000/. yearly, which would be equal to a capital of 24,
000,000/. sterling gained forever to the country by this trifling
increase in the growth of one article, and that in England and
Wales alone;" a quantity sufficient, we may add, to feed all
her starving millions in the manufacturing districts ; and if,
by any means, a similar increase could be effected in her other
productions, she would be able to banish forever all fear of
want, which now so frequently threatens to undermine the
pillars of the throne itsdf.

But while the soil of England has reached nearly the maxi-
mum of fertility, ours in this country has not. Let us then cal-
culate the value of some slight improvanmts at home, which
with the aid of science and skill, may easily be made, in a few
years, with little or no expense to the country.

1. Take our wheat crop for 1839. As the number of
acres is not given, we cannot decide with perfect accuracy
the average per acre ; but taking the estimate made for the
state of Massachusetts the same year, the quantity is about
15 bushels per acre. The Middle and Western States yield
a much larger quantity, I think therefore we may be safe in
estimating the average at 20 bushels per acre. Then 91,
642,957 bushels annually produced, would require the culti-
vation of 4,582,147 acres of land. Suppose now that by the
use of improved modes of culture, selection of seeds, etc. we
could make our wheat lands produce, on an average, as much
as those of England, 26 bushels instead of 20 to the acre, (and
this certainly might be done), this increase would amount
annually to 27,492,882 bushels. This would add as many
dollars to the national income, and would be equal to an in-
vestment of 458,214,700 dollars!

2. Let us apply the same calculation to corn, rye, oats, etc.
and as 387 millions of bushels are corn, we may estimate
these products, upon an average, at 30 bushels to the acre*

INTRODUCTION. 27

There would then be 18,343,318 acres devoted to these crops.
Suppose now by the application of scientific principles the
same increase per acre might be effected, viz. 36 bushels in-
stead of 30, there would be added to the quantity now ob-
tained 110,059,908 bushels ; and if we estimate the whole at
50 cents per bushel, it would add 55,029,954 dollars to the
annual income of the country, equal to an invested capital of
917,165,900 dollars!

3. Apply the same calculations to the potato crop ; and
taking the crop in Massachusetts of 1839 for the average, at
200 bushels per acre, the 113,183,619 bushels raised in
this country in 1839 would require 565,918 acres of land.
Suppose now an increase of 25 bushels per acre, (an estimate
far below what might l^e realized,) and there would be added
to the present quantity of this crop, 14,647,950 bushels;
which, at 20 cents per bushel, would amount to 2,929,590
dollars, equivalent to a capital of 48,826,500 dollars !

4. If now we estimate the total income to the national
wealth, by this addition to the cultivated crops, it will amount
to the sum of 85,4.52,526 dollars, equivalent to a capital of
1,424,207,100 dollars! But this sum is derived from but a
few of the products of the soil. When we take into account
the hay and other agricultural productions, and allow the
same relative increase, the amount would be more than
doubled. Thus a sum of money might easily be realized
which would be sufficient to found all the colleges and institu-
tions of learning, build all the rail-roads and canals, which the
wants of the country might demand during all coming time !

Let us now confine our estimates to a narrower sphere.
" Suppose that the agricultural survey," says Mr. Colman,
in his Fourth Report of the Agriculture of Massachusetts,
" may have been, or may have proved instrumental in induc-
ing, upon an average, by improved cultivation, an increase of
one hundred bushels of corn to every town in the Common-
wealth ; this, at seventy-five cents per bushel for corn, and

28 INTRODUCTION.

ten dollars per ton for corn fodder, would be upwards of
28,000 dollars. Suppose it may conduce to the production
of an average of one hundred tons of compost manure
in each town in the Commonwealth, which must be valued
at one dollar per load ; this would exceed a yearly income of
60,000 dollars, to say nothing of the permanent improvement
it would effect in the soil. Suppose that it may conduce to
the redemption of 1000 acres of peat bog, which is now worth-
less, converting it into productive meadows yielding two
tons of hay to the acre, and keeping up its condition ; this
would be little more than three acres to a town ; and rating
its value by its income (it cannot be estimated at less than
150 dollars per acre) this would be an increase of the pro-
perty of the State, which may be safely called an actual crea-
tion of land, to the value of 150,000 dollars, and a permanent
income of more than 20,000 dollars per year. Here is no
extravagant calculation, to say nothing of many other forms
in which the influence of the survey may be felt."

Finally, in order to obtain just views of this subject, it must
be remembered, that the above improvements imply a very
great intellectual and moral advancement in the agricultural
community ; an elevation of the popular mind, the value of
which cannot be estimated by bushels of grain, by silver and
gold coin, but by the purity, stability and extension of our
social, civil and religious institutions ; and by the increased
facilities for cultivating the higher powers of man. The in-
crease of national wealth is a desirable and laudable object
of pursuit, but it is mainly from the intellectual and moral
influence which an improved agriculture will exert upon so-
ciety, that we can derive an adequate idea of its magnitude
and importance. Imperfect as the science of agriculture now
is, and imperfectly as it is represented in the following pages,
the interest is so vast, that if any slight improvement is secu-
red, I shall not deem my labor wholly lost.

BIOLOGY OF PLANTS

CHAPTER L

THE VITAL PRINCIPLE.

Material bodies have been divided into three kingdoms,
animal, vegetable and mineral. This division is an obvious
one, and is a convenient mode of classifying the phenomena
which each presents to the view of the common observer.

But a more philosophical examination discloses the fact,
that animals and vegetables have many points of analogy, and
that they both differ essentially, from minerals. This differ-
ence is manifested in various ways, in the mode of their origin,
their food, growth and dependance upon other matter, foreign
to themselves. But all these different modes of existence
may be traced to a peculiar power, which has been called the
vital principle ; hence a more philosophical division of natural
objects, is into those which arepossessed of life, and those which
are destitute of it. The former have been called organic,
and the latter inorganic bodies.

Sect. 1. Defnitions. — Proofs, Nature and Uses of the Vital
Principle.

1. Biology is the science of life. The term is derived from
two Greek words, and is similar in signification to the term
Physiology. It includes all the agencies and conditions which
are essential to the existence and reproduction of living beings.
The term Biology of plants signifies nearly the same as vegeta-
ble physiology. It includes that peculiar power which has been
called the " vital principle,''^ and its connection with those agen-
3

30

BIOLOGY OF PLANTS.

cies which in any way act upon it, or seem necessary to its de-
velo|)tnent in the processes of vegetation, such as soil, food, air,
water, gravity, affinity, heat, light, electricity and the agency of
man.

2. " An organized body is one in which all the parts are mu-
tually means and ends,"* that is, " each portion ministers to the
others, and each depends upon the other," the parts make up the
whole, but the existence of the whole is essential to the pre-
servation of the parts. The parts are organs, and the ichole is
organized.^''
» " We conceive animal life as a vortex, or cycle of moving matter,
in which the form of the vortex determines the motions, and
these motions again suj)iJort the form of the vortex ; the station-
aiy parts circulate the fluids, and the fluids nourish the perma-
nent parts."t

The same view may be taken of plants. In some vegetable
products, the organs appear in a distinct form, as in the wood,
leaf and blossom. In other products, as starch, gum and sugar,
no such marks of organization can be distinguished. All orga-
nized bodies are the products of the living principle, whether
those now j)0ssessed of life, or those that have been possessed
of it, or those which have been derived from living bodies, as
alcohol and vinegar.

3. A plant is an organized and living substance, springing
from a seed or germ, which it reproduces. It is composed of
an irritaole, elastic matter, called tissxie. Tissue is of two kinds,
the cellular analogous to the flesh and soft parts of animals, and
the vascular, which is similar to the bones of animals.

4. All plants are made up of cells or
ve^sicks, (Fig. I, a a a,) of different forms,
with thin, transijarent walls. When these
cells press against each other, small in-
tervals are lefl between them which al-
so form tubes, called intercellular canals.
They are the vessels in which the sap
is carried up from the roots to the leaves.
When these intervals increase in size,
so as to exceed many times the diame-
ter of the cells, they are called the pro-
per vessels.

Fiff

Kant.

t Whewell.

DEFINITIONS AND DESCRIPTIONS.

31

Fig. 3.

5. Cells are of three kinds.
(1) Those of the bark and pith,
of an elhpsoidal form. (2) Elon-
gated cells of tlie liber aiul wood.
Tliese cells constitute the in-
terior of the hark, and are the
basis of wood]) fibre. (3) Cells
of the medullarrj rays. The
medullary rays pass from the
pitii to the bark through the
wood, as in Fig. 2. c m m m.
These cells also have intercel-
lular canals.

6. Spiral vessels exist also in the more i)erfect plants.
They are called spiral because they are fibres twisted
like a cork-screw, (Fig. 3,) around an empty space.
These cells occur only in wood, and are found in bun-
dles. Each bundle contains about thirty or forty spi-
ral tubes. A new bundle is formed every year, con-
stituting the annual layer of icood, or concentric rings,
as in Fig. 2. They are supi)osed to be air vessels. In
grasses and grains these spiral vessels constitute the
part around the interior of the hollow stem.

7. Pores are oblique openings or slits in the epider-
mis or cuticle, so small tJiat a square inch of the e[)ider- ''''^^:i:>^
mis of the kidney bean contains more than 300,000 £^
pores. These pores are found chieliy on the under side of the
leaf, and are the organs of transpiration.

8. Epidermis or cuticle is a very thin
membrane which envelopes the soft
parts of plants, as the leaves. It is
sometimes composed, in part, of silica.

9. Wood is formed of bundles of
spiral tubes, (See Fig. 2,) surrounded
by elongated cells. The inner hark,
(Fig. 4. 1,) is called the liber, and in
the spring a mucilaginotis matter call-
ed cambium is interposed between the
liber and the wood ; Irom this the
first soit wood is formed, called albur-
num, which is annually attached to
the tree, while a thin layer is formed
on the liber or bark, 2, 3, 4, 5.

32

BIOLOGY OF PLANTS.

In Fig. 2, c represents the pith, b the heart wood, a the al-
burnum, II m the bark. The annual layers of wood, the medul-
lary rays and the tubes are also represented in tliat figure, which
is a representation of a section of the branch of a tree.

10. The process of converting tlie cambium into alburnum
and other vegetable substances, such as sugar, gum, starch, etc.
is called assimilation ; that of rejecting matter by the roots, ex-
cretion and by the leaves, transpiration. When substances are
thrown off from the leaves, they are also said to be exhaled ; and
when they are taken in by the leaves, they are said to be inhaled
or absorbed.

Agricultural Chemistry is a term which has been generally used
to denote the ai)plication of science to Agriculture. It attempts
to explain the ijifluence of earth, air and water upon plants.

That branch of the subject, which relates to the soil, as formed
of simple minerals and rocks, is sometimes called Agricultural
Geology. But as the chemical and geological agents are, in the
processes of vegetation, subjected to the principle of life, it seems
more appropriate to include the vital principle; the conditions
of its action ; the influence of other agents upon it ; its produc-
tions, with their composition and source, under the term Biol-
ogy of Plants ; while the subject of soils and manures is placed
under the term Geology and Chemistry of Soils.

Plants and animals differ in many respects from each other,
as in their structure, in the nature of their food and in the
mode and time of taking and digesting it, as well as in being
governed by many different laws, but yet they both agree in
possessing a living principle. This power is probably the
same in both, and is characterized by its operations, and by
its pervading every part of organized bodies. Mechanical
and chemical agents are subordinated to it, in the living sys-
tem, and would be wholly inefl^cient without it.

In the stomach of animals, for example, this power is the
principal agent in elaborating the juices required to digest the
food. It enables the lacteal^ or small tubes which open their
mouths into the alimentary canal, to select, from the general
mass, whatever is fitted for nourishment, while it permits what
is injurious or useless to pass by. It sends this to the heart,

THE VITAL PRINCIPLE. 33

and gives it its never ceasing pulsations. It follows the blood
to the lungs, and watches over the changes which are wrought
there by the atmosphere. It returns with the blood to the
heart, and propels it through every part of the system, where
it assimilates it to the living body ; and finally, when the liv-
ing flesh and bone have served their purpose in the animal
system, and the matter is no longer fitted to give strength and
life to the part, it is vitality which removes it to make room
for fresh particles which this same power has prepared to fill
the place. Thus the vital poicer is active during every mo-
ment of animal life, in converting dead into living matter,
and of removing it when it is no longer fitted to form a part
of the living system. It is in the bones and muscles, in the
tendons, glands and skin ; it pervades the entire body, and
presides over all its healthful changes and operations.

It distinguishes man from the dust on which he treads. By
it he lives and moves ; by it he resists the laws of nature which
assail him on every side ; by it he wards off the attacks of
disease, or expels it when it has taken possession of his body ;
by it he clothes himself again with strength and beauty. It is
this vital power within, that, by its constant and all-pervading
energy, builds up and keeps in action that wonderful and fear-
ful tenement which is his earthly habitation. Nor does it
cease its ever active agency during all the' changes and acci-
dents of life, until his spirit departs for another world.

The vital principle exerts a similar influence, though not
to the same extent, upon vegetables. It is this power which
enables the roots to derive* nourishment from the soil, and the
leaves from the air. It aids in carrying up the sap through
small tubes to the leaves, where a change is wrought upon it
by contact with the atmosphere. It sends the prepared nu-

* The powers of absorption and circulation of the sap^ to a certain
extent, is clue to chemical and mechanical laws, but it is doubtful
whether the phenomena can be w^holly explained without the aid of
this peculiar power.

3*

34 BIOLOGY OF PLANTS.

triment down between the bark and wood, (in perennial
plants,) and assimilates what is nutritious to the livincr tree;
and, although most of the matter remains, still there is a quan-
tity taken in which is excreted by the roots, or transpired
through the leaves as unfit to enter into its composition.

This power exists in the roots, stem, leaves, juices, flowers
and fruit, and presides over all the changes which are carried
forward in the vegetable economy. In this case also many
of the processes are, in part, purely chemical or mechanical ;
but these forces would be of no avail to form the vegdable
products, if the living power or vital energy were absent, and
hence we may ascribe the effect to that power, just as we do
chemical changes to affinity, although many other agents may
operate in unison with it, and modify its action.

As some chemists are disposed to doubt the existence of
such a power, attempting to explain the phenomena of vege-
tation by chemical and mechanical forces, and particularly
by what are denominated " chemical transformations," I will
proceed to the

Proofs of its existence. The existence of such a power in
plants and animals is susceptible of the same kind of proof as
the power of gravitation or attraction in general. We cannot
subject it to the test of the senses, as we can caloric, light and
electricity. We infer its existence from the effects which are
produced, and which cannot be shown to be caused by those
agents which are capable of sensible demonstration.

That such a power exists in animals might be easily shown.
But it is more important for our purpose to exhibit evidence
of its existence in plants ; in which this force differs in its
operations, in the conditions requisite for its development, and
in the instruments, by which its existence is continued.

I. Vegetables j^ossess the poioer of resisting or counteracting
the laws of affinity, gravity, heat and cold.

1. The process of the absorption of food, and its elabora-
tion and assimilation, takes place in opposition to the laws of

PROOFS OF VITALITY. 35

chemical affinity ; for as soon as the plant dies, this agent be-
gins to exert its power. The elaborated juices, no longer pre-
served by the vital principle, exert their mutual affinities, and
the whole plant in time is resolved into its original elements.
This power of resisting ordinary chemical laws, and of con-
trolling them in such a way as to make them subservient to
nutrition, evinces a peculiar vital energy,

2. Gravity is constantly tending to bring the plant and its
juices to the earth ; but in opposition to this power the sap
ascends, and the plant or tree attains in some cases an eleva-
tion of more than one hundred feet from the surface of the
ground. A part of the matter which composes the tree is thus
carried up in opposition to gravity. It is true that it is car-
ried up slowly, and in small capillary tubes, in which mechan-
ical laws operate to some extent, still this will not wholly ac-
count for the fact. It requires vitality to effect its ascent.

3. Heat and cold, two powerful agents of unorganized bo-
dies, are resisted by vegetables within certain limits. The
temperature of the juices of plants, and of their solid parts,
does not rise or fall with that of the surrounding medium.
The living vegetable will continue to flourish at a temperature
sufficiently high to produce disorganization after it is dead,
while the juices are said to circulate slowly during the cold
of winter ; for although the temperature of the juices is far be-
low the freezing point, they do not always congeal unless they
are taken from the tree.

This power of resisting the extremes of heat and cold is
very striking in the case of some animals, which, when exposed
to a temperature of 300° F; or to — 80° F. retain constantly a
temperature at 9S or 100° F. Vegetables possess this proper-
ty in a less degree, but sufficiently to prove its existence. This
effect cannot be wholly* accounted for without supposing the
existence of a peculiar vital power.

* The heat which is found in vegetables is partly due to chemical
changes. By the assimilation of the matter taken into the tree by the

36 BIOLOGY OF PLANTS.

II. Eicitahility in vegetables indicates the existence of a
vital principle, and is one of its distinguishing properties. It
is a capacity of being acted upon by natural and artificial stim-
ulants, such as light, heat, electricity, manures and saline com-
pounds.

1. Light. The stimulating influence of light upon the
leaves and blossoms of vegetables, cannot have escaped the
most common observation. The leaves turn their upper sur-
faces to the sun, and the blossoms of many plants close during
the night, called the deep of plants, and open only when sub-
jected to the influence of that agent. Plants that grow in the
shade are not so highly colored nor so vigorous, as those which
are exposed to the light, and generally the branches and the
fruit are the most vigorous on the south side of the tree. The
ripe ears of grain generally lean toward the south. The
branches grow in the direction of a crevice, in the wall of a
ceflar, through which light is admitted. These, and a great
variety of phenomena prove the existence of a vital power, or
capacity of being excited by the agency of light.

2. Heat exerts a powerful influence upon the functions of
plants. This is seen in the germination of the seed, a certain
temperature being requisite to develope the germ, and enable
it to throw out roots and stalks. In the production of leaves,
flowers and fruit, each development depends, to some extent,
upon the degrees of heat which are applied, — hence the vari-
ous means which are employed to increase or diminish the

roots and leaves, gases and liquids arc converted into solids, and by a
well known law in such cases, heat is evolved; the insensible heat be-,
comes sensible ; on the same principle, as the temperature of tlie air di-
minishes, and the sap beg-ins to freeze, a quantity of heat is evolved.
The power of resisting heat is partly accounted for on the principle
that the plant transpires a large quantity of water through the leaves,
and as the heat increases, the quantity of water is increased ; by the
conversion of the water into vapor, a large quantity of caloric becomes
insensible, the external heat is thus taken up, and the temperature of
the plant remains below that of the surrounding medium.

PROOFS OF VITALITY. 37

temperature by hot-houses, inclosures, shades, etc. The vi-
tal energies of the plant are nearly suspended during the win-
ter season. But on the return of spring, the heat which it
brings with it, excites the living functions, and enables the plant
to put forth its leaves ; and, as the heat increases, its flowers
and fruit ; all of which not only prove the existence of such a
principle, but also exhibit a most important property of it.

3. Ehitricity has probably a much more powerful effect
upon the functions of vegetables than has been generally sup-
posed, and tends powerfully to quicken their vital energies.
Davy proved that seeds germinate sooner in water, charged
with positive than with negative electricity.

4. Artificial stimulants, such as manures and saline com-
pounds, and even acids and alkalies, produce effects upon the
functions of vegetables which can only be accounted for on
the ground that they contain a vital power which is peculiar
to them, and different from the ordinary agents of dead matter.

III. Irritability is another property of vegetables which
proves the existence of the vital principle. This property is
conspicuous in the leaves of certain plants, as the sensitive
plant and Venus' jly trap ; but is more generally found in the
stems, stamens and tendrils, as in the pea, bean and vine.

IV. The productions of the vegetable kingdom are decisive
proofs of the existence of a vital power. Most of these pro-
ductions cannot be formed by any known chemical agents.*
The chemist can analyze them and show their composition to
be oxygen, hydrogen, carbon and nitrogen, with a small quan-
tity of alkalies and metallic oxides ; but he has no means of

* There is hardly an exception to the rule, that in producing orga-
nic substances, as they are called, the chemist must employ other or-
ganic substances which are as yet beyond his art — which, so far as we
know, can only be formed under the direction of the living principle.
In no one case can he form the substances of which animals and plants
chiefly consist, out of those on which animals and plants chiefly live.^ —
Johnsons Lectures, p. 190.

38 BIOLOGY OF PLANTS.

combining these elements so as to reproduce them. The pro-
duction of woody fibre, gluten, starch, sugar, gum, resin,
vegetable oils, acids and alkalies, with a few exceptions, whol-
ly exceed the power of any known chemical or physical agent.
They can be accounted for only by supposing a new and pe-
culiar po\\^er inherent in the vegetable, which we call the pow-
er of life or the vital principle.

Nature of vitality . Of this we are wholly ignorant. We
know it only from its effects. Like affinity and attraction,
it is an ultimate power, at least, so far as science is concerned ;
for aught we know it is the direct power of God exerted in
this particular way.

Various hypotheses, however, have been suggested to ac-
count for the phenomena of life. A few of these may proper-
ly be introduced in this connection.

1. Some, as Paracelsus, held to a spiritual being. The
business of digestion was performed by the demon Archaeus,
who had his abode in the stomach, and '' who, by means of
his alchemical processes, separates the nutritive from the
harmful parts of our food, and makes it capable of assimila-
tion.

2. Others, as Silvius, conceived that the vital functions
were due to chemical agents, and that the power of life con-
sists in the action of acids and alkalies, in fermentation and the
like processes.

3. A third class have proposed a mechanical hypothesis,
which originated about the time, and was the result of the
splendid discoveries of Galileo and Newton. The phenomena
of life were due to the form of the particles of matter, their
motions and mutual attractions.

4. A fourth class suppose the existence of a vital jluid, up-
on which the peculiar functions of life depend. This hypo-
thesis was proposed by Frederic Hoffinan of Halle, 1()94.
The vital fluid was a material substance acting through the
nerves, and producing the actions of all the other organs. This

NATURE OF VITALITY. 39

is the " Ether, which, diffused throughout all nature, produces
in plants the bud, the secretion and motion of the juices, and
is separated from the blood and lodged in the brain of an-
imals."

5. A fifth hypothesis, first proposed by Aristotle, was re-
vived by Stahl, and refers the phenomena of life to an ani-
mal soul, or immaterial principle wholly distinct from a soul, as
the responsible and intelligent part of man's nature. This
theory has been adopted by many, but it is evidently inappli-
cable to plants. This objection appears to be fatal to its truth,
although the Physical School, as those have been called who
adopted this theory, are mainly right in this, that in ascribing
the functions of life to a soul, " they mark strongly and justly
the impossibility of ascribing them to any known attributes
of body."*

Various attempts have also been made to define life, or to
analyze the idea of it.

1. The most correct definition of life is given by Bichat,
and modified by Whewell. " Life is the system of vital func-
tions" These functions are of two kinds, those which per-
tain to organic life, which are the same both in animals and
vegetables, and those which belong to animal life, which in-
clude sensation and voluntary motion.

2. Some suppose that the idea of life is simple, and hence
the effects of it are explained by reference to a single prin-
ciple.

3. Others attempt to separate life into a series of vital func-
tions, such as secretion, assimilation, absorption, etc. and
hence muke the idea of it complex.

But in all these attempts, there seems to be a necessity of
referring the phenomena of life to some distinct force. This
force has been variously denominated organic attraction or
vital attraction, organic affinity or vitcd affinity. Professor

* See Whewell's Philosophy of Inductive Sciences, Vol. II, in
which these and other hypotheses are examined.

40 BIOLOGY OF PLANTS.

Mliller calls it organic assimilation, and this seems to accord
with the usage of biological writers.

But whatever name physiologists may give to this power,
and whatever attempts they may make to analyze or define
the idea of life, whether we study it in the separate functions
of secretion, assimilation, or any other organic change, its
nature is wholly unknown to us. We know what its effects
and laws are, and can better understand them by conceiving,
as their cause, a peculiar poiar, essentially distinct from the
ordinary agents of dead matter, although producing both me-
chanical and chemical effects.

But on the supposition that such a power exists, what influ-
ence can it exert upon the theory or practice of agriculture ?
In answer to this inquiry, it may be observed,

1. That it is useful to have reference to the irital power ,
in the whole process of tillage. Regarding this power as the
great agent in the process of vegetation, we may refer all the
productions of the farm to it as a cause.

The science of tillage is a knowledge of those laws by which
the vital power is governed, and of the conditions which are
necessary to its activity ; and practical farming consists in
acting according to its laws, and in supplying those conditions
which are required for its most perfect development.

I will illustrate the relation which the vittd power in plants
sustains to the science and practice of agriculture, by a refer-
ence to the science and practice of medicine. What is the
science of medicine? It is a knowledge of those laws which
govern the vital power, as it exists in the hunjan species, and
of those conditions which are necessary to the complete de-
velopment and perfection of this power, including, of course,
whatever may obstruct it in its operations. And what is the
practice of medicine? It is mainly concerned in applying
remedies to remove the obstacles to the proper action of vital-
ity ; a provision being made by our Maker in our appetites,
so that we become our own physicians, in supplying moi?t of

USES OF VITALITY. 41

the conditions, which are necessary to keep up the continu-
ance and activity of this principle. But in the vegetable king-
dom, nature has not given to the plant the power of making
known its wants, but has left it to the farmer to learn what
they are, and, if he wishes the seed or the plant to develope
itself in the most perfect and useful manner, he must supply
them with all those conditions, which their peculiar constitu-
tion requires. He must become acquainted not only with their
natural enemies, but with their particular friends, and defend
them from the attacks of the former, by surrounding them
with the strong protection of the latter.

Unskilful farming, like quackery in medicine, has but one
specific for every species of disease. It is a subject of deep
regret, that imicli of the practice of medicine, and all kinds
of quackery, are but a series of experiments upon the capa-
bilities of the vitcd pmvcr ; and, although our Creator, as if
foreseeing the trial to which it would be subjected, has given
it a wonderful degree of elasticity and accommodation to cir-
cumstances, although he has endowed it with an almost uncon-
querable power, yet when it has been long heatcn, bruised
and abused, it will cry out under its tortures, and make its suf-
ferings known by the emaciated form, the languid ptdse, and
the feeble step.

It is scarcely less to be regretted, that quackery in farming
is little else than experiments upon the capabilities of the vi-
tal power in seeds and plants ; and although they too have a
most elastic and yielding constitution, yet the neglected plant
will tell you, by its stinted growth and scanty fruits, of the vio-
lence which is done to its vital energies.

2. A correct view of the vital power may serve to awaken
interest, and excite admiration in view of the simple, yet beau-
tiful kws which the Creator has established for the production
and perpetuation of animal and vegetable bodies.

If we take an egg, for example, and examine it, we shall
find it has a hard covering, composed of carbonate of lime,

4

42 BIOLOGY OF PLANTS.

similar to chalk or marble ; and a semi-fluid mass of white
and yolk within, consisting mostly of a substance which chem-
ists call albumen. It gives no signs of life. It hardly exhibits
the marks of organization, and yet, let that same egg be sub-
ject to warmth for a few weeks, and you will find that it has
been touched by the life-giving power of the Creator ; that he
has impressed it with a living energy, which will soon be de-
veloped in an organized, sensitive being ; so peculiar in its
composition, that no chemist can ever produce its like, so
perfect in every part of its structure, that no mechanic can
form even the smallest feather that tips the wing of the chick.

Or, if we take a seed, a kernel of corn, and examine that,
we shall find it a hard, dry substance, different in composi-
tion and appearance from an egg, consisting mostly of mucil-
age and starch. It too is the most unlikely thing to be pos-
sessed of vitality. You may keep it a hundred years, for aught
I know, and it is still the same apparently dead substance.
But only cast it into the earth, subject it to heat and moisture,
and after this long sleep of a century,* it will also show, that
when it was matured upon the parent stalk, perhaps in some
remote corner of the globe, the Creator treasured up and
guarded in it a vital power, which will be exhibited by its tak-
ing root downward, and springing upward a living organized
body, provided with organs capable of converting that which
contains the contagion of death into the staff of life.

And what serves to increase our admiration, is the fact,
that this power is not confined to a few seeds which are es-

* Seeds probably possess different powers of life, some preserving
their vital principle through centuries of time, while others have an
ephemeral existence under any circumstances. The reasons for this
difference are unknown to us, and apparently depend upon a First
Cause, over whicli we have therefore no control. * * I have myself
raised raspberry plants from seeds found in an ancient coffin in a bor-
ough in Dorsetshire, which seeds, from the coins and other relics met
with near them, may be estimated to have been sixteen or seventeen
hundred years old. — Lindlcy.

DEFINITIONS AND DESCRIPTIONS. 43

pecially intended to perpetuate the species, but all alike are
endowed with it, whether intended for the support of man or
other animals ; whether cast on rocks, into the water, by the
way side, or into the fertile soil. While countless millions are
annually produced, only here and there one is permitted to
engage in the process of reproduction ; so provident has nature
been, so careful to ensure the perpetuity of the race.

3. A proper view of the vital power may serve to im-
press the tiller of the soil above all other men, with the most
important moral lessons. Particular attention should be
given to it because it is unseen and secret in its operations,
and is not therefore properly considered. No credit, so to
speak, is given to it. And when the farmer casts in his
seed and gathers his golden harvests, he forgets the most
important agent, which has been working, with unceasing en-
ergy, to fill his stores with food. Nor does he consider, while
enjoying the rich rewards of his industry, the benevolent pro-
vision of his Maker in giving to every kernel of his grain the
power of producing future harvests, and supplying future wants.

When he looks over the face of the earth and sees what an
infinite variety of form, color and property, characterizes the
plants which everywhere cover its surface, it may serve, at
least, to humble his pride, and confound his wisdom, when he
reflects that he cannot tell how a spear of grass grows, much
less impart a single tint to the gorgeous coloring with which
nature has adorned her covering. But he may see in every
stalk of grain the workings of a hidden and mysterious power,
the evidence of an all-pervading and beneficent Intelligence.

Sect. 2. Defi,mtions. — Conditions necessary to develope the vi-
tal principle in the seed, bulb and bud.

1. A seed is a living body, capable of producing a new indi-
vidual of the same species. "It is a reproductive fragment, or
vital point, containing within itself all the elements of life." The
seed consists of three parts, cotyledons, radicle and plumula.

44

BIOLOGY OF PLANTS,

2. Cotyledons are the seed lobes, as in the Fio- 5
garden bean, (Fig. 5,) and are composed of
matter to nourish the germ a 6, betbre it
can obtain food from the soil. Some seeds
have no cotyledons, such as those of the
mosses and ierns, and are called acotyle-
donous ; other seeds have but one cotyledon,
such as those of grasses, grains, etc. and
are called monocotyledonous ; otliers still
have two, as those of leguminous plants, (the pea,) and are
called bicotyledonous. A fourth class hav^e more than two cotyle-
dons, and are called polycolylcdonoiis^ of which the seeds of the
pine and hemlock are examples.

3. Radicle. The radicle (Fig. 5, h) is that part of the embryo
which shoots downwards into the earth, and forms the roots of
plants.

4. Plumula. The plumula, a^ is that part which shoots up-
ward into the air, and forms the stalk or stem, branches, leaves
and fruit.

5. Bulhs are tubercles connected with the roots of Fig. 6.
plants, and contain the embryo of the future plant.
The potato (Fig. 6) is a well known example of a
bulb.

6. Buds are vital points along the stem, situated
generally at the axles or angles of the leaves. The
bud (Fig. 7, « c) is caj)able of forming leaf buds, flowers,

Fig. 7.

DEFINITIONS AND DESCRIPTIONS. 45

fruit or branches ; or when separated from the stalk, of produc-
ing a plant, not only of the same species, but of the same va-
riety ; -while seeds produce similar species, but not the same
varieties.

7. Eye is a term applied to vital points on bulbous roots, as
the potatoe, (Fig. 6, a.) These {)oints are also found on the stem,
(Fig. 7, rf,)and are similar to the germ, or vital pouit of the seed.
Tliey are in fact the true buds.

8. Chemical transformation is a term applied to the changes
which tcike place in compound bodies, when subjected to the
influence of other substances. If the change consists simply in
the new arrangement of tlje atoms of the conijjound, the change is
called catalytic ; but when the change takes place in the organs of
plants, and consists in the body's yielding one ingredient, and
forming by its remaining elen^ents, or by elements obtained from
the acting body, a new compound ready to pass through other
similar changes, then it is called properly a transformation ; and
when a series of changes are thus produced upon water, or any
other substance, the body is said to pass through chemical trans-
formations.

"An organic chemical transformation is the separation of the
elements of one, or of several combinations, and their reunion
into two or several others, which contain the same number of
elements, either grouped in another manner, or in different pro-
portions."— Liehig.

The catalytic force acts by mere presence. The combination
of two bodies in contact with other compounds, causes the latter
to enter into a similar state. The process of fermentation will
serve to illustrate the nature of this force. A small quantity of
matter, in a state of fermentation, causes an indefinite quantity
to enter into a similar state, as when yeast is introduced into
dough.

9. A simple substance is one which has never been resolved
into two kinds of matter, such as charcoal, silver, gold, iron, etc.
The number of simple substances is fifty-five ; and they are re-
presented by letters or symbols; thus, O stands for Oxygen,
H. for Hydrogen, C for Carbon, and N for Nitrogen. The quan-
tity in which any body combines, is expressed in numbers, hy-
di'ogen being taken for unity. Only fourteen simple bodies are
found in vegetables, of which the following are the names,
equivalents and symbols. Hydrogen, symbol H, equivalent
1 ; Oxygen, Symb. O, Equiv. 8, and Nitrogen, N — 14, which, in

4*

46 BIOLOGY OF PLANTS.

their pure state are gaseous bodies ; Carbon C — 6.12, Silicon
Si — 22.5, Phosphorus P — 15.7, and Sulphur S — 16.1, which are
called non-metallic combustibles, (and for which Dr. Dana has
proposed the term wrefs) ; Potassium K — 39.15, Sodium Na —
23.3, Magnesium Mg — 12.17, Calcium Ca — 20.5, Aluminium
A\ — 13.7, Iron Fe — 28, and Manganese Mn — 27.7, which are
metals.

10. Compound Bodies. A compound body is one which is
composed, or made up of two or more simple bodies. The
number of compound bodies is unknown. They are represen-
ted by adding the symbols of the simple substances, which en-
ter into their composition; thus, HO represents a compound
formed by the union of oxygen and hydrogen (water). The
equivalent is the sum of the equivalents of the simple bodies
thus combined, HO=l-|-8=9, which is the equivalent for wa-
ter.

11. When oxygen combines with any other substance, the
compound is called an alkali, an alkaline earth, an oxide or an
acid; thus potassa, soda and lithia are compounds of oxy-
gen with metals, and are alkalies. Ahunina, lime and magne-
sia are alkaline earths, and oxide of iron and of manganese are
oxides. Oxygen combined with nitrogen forms nitric acid ;
with sulphur, silicon and carbon, sulphuric, silicic and carbon-
ic acids.

12. When acids unite with the alkalies, alkaline earths or
metallic oxides, the class of bodies formed are called salts.
When the nuniber of the equivalents of an acid and an al-
kali are equal, the salt is called neutral. When the alkali is in
excess, the salts are called by some sub-salts, and when the
acid is in excess they are sometimes called super-salts. The
name of the salt terminates in ate, as phosphates, carbonates,
nitrates. When carbon, phosphorus, silicon and sulphur unite
with each other or with the metals, they are termed carburets,
phosphurets, siliciurets and sulphurets.

13. An acid and an alkali unite in definite proportions, and
mutually neutralize each other. TJuis, 40 parts of sulpliuric
acid is neutralized by 48 of potash, or 20 of magnesia, or 28 of
lime, or 32 of soda, or 17 of ammonia ; hence these alkalies may
be substituted for each other, whatever acid is used ; and the
same is true of acids — hence the term equivalent, because they
may be substituted for each other, and form neutral salts.

14. Almost the entire mass of every vegetable may be resol-
ved into two or more of four simple bodies, viz., oxygen, hydro-

DEFINITIONS AND DESCRIPTIONS. 47

gen, carbon and nitrogen. These are called the organic constitu-
ents of plants, because when any jjortion of vegetable matter is
burned, it either disappears entirely, or leaves behind a small
quantity of ash.

15. The ash is composed of several simple bodies, and hence
these latter are caHed the inorganic constituents of plants.

Sonje knowledge of the organic constituents of plants, ap-
pears to be necessary for understanding the subject of this sec-
tion, and, for the information of those who have not attended to
elementary chemistry, a short description of them is here in-
serted.

1. Oxygen is found in the state of a gas in the atmosphere,
mixed with nitrogen, and constitutes one fifth part of its vol-
ume; eight-ninths of water by weight is also oxygen gas. Be-
side this, the whole crust of the globe is composed of oxydized
substances, that is, of substances combined with oxygen.

In its pure state, oxygen is a transparent gas, without color,
odor or taste, and is a little heavier than the air. It unites
chenjically with a great number of substances. If a lighted ta-
per is plunged into it, the brilliancy of thd flame is much in-
creased, and if heated iron be immersed in a jar of pure gas,
the combustion is so intense as to melt and burn the iron. This
substance is always one of the agents in all our fires and lights ;
hence its importance. Oxygen also is the supporter of the res-
piration of animals. No animal can live for any length of time
without it.* It is no less essential to the existence of the veg-
etable kingdom.

2. Hydrogen is chiefly found in water, forming one-ninth part,
from which it may be obtained by putting into it iron or zinc
turnings and sulphuric acid. It is found in most liquids, and
in all animai and vegetable bodies.

Hydrogen in its pure state exists in the form of a gas, no way
distinguished in its physical properties from oxygen, with the
exception of its being sixteen times lighter, and a much more
pow^erful refractor of light. When a lighted taper is inmiersed
in it, the hydrogen is set on fire, but the taper is extinguished.
If air or oxygen gas is mixed with it, and the flame of a candle
brought in contact, the mixture will explode, and the product
will be water. Animals are suffocated by it, and balloons ai-e
made to ascend.

Water. One part of hydrogen and eight of oxygen, by weight,

^ See Gray's Chemistry, p. 131.

48

BIOLOGY OF PLANTS.

form water, (Symb. HO. eq.==9), a substance remarkable in its
relation to vegetation from the ease with which it is decompo-
sed, when subjected to the influence of the vital principle, as it
passes with great facility, through several transformations in the
vegetable organs.

3. Carbon is the most abundant substance in vegetable bo-
dies. In its pure state, it exists as the most valued and beauti-
ful of gems — the diamond. Common charcoal is nearly pure
carbon. All kinds of coal are essentially composed of it ; great
quantities are also locked up in the rocks, in the form of car-
bonic acid, (fixed air). Common charcoal is a well known sub-
stance ; it burns with a white ligiit, but with little flame. As it
constitutes from 40 to 50 per cent, of all vegetables, it has much
to do in the processes of vegetation. One of its most impor-
tant properties is the power of absorbing several gases, a pro-
perty upon which its utility as a maniu-e depends.

Carbonic acid. Carbon coml)ines with oxygen, and forms car-
bonic acid, or fixed air. This is a gaseous, transparent sub-
stance, two and a half times heavier than common air. It is
composed of one equivalent of carbon, 6.12, and two of oxTgen,
16 = 22.12. Its symbol is CO^. Carbonic acid is readily ab-
sorbed by water, to which it imparts a sour, lively taste ; also a
brisk, sparkling flavor to all fermented drinks, as beer. It is
sup{)osed to yield more carbon to plants than all other substan-
ces united.

4. JViti'ogen exists in the atmosphere, of which it forms 80 per
cent. It is never absent from any part of the vegetable struc-
ture, but exists in small quantities. Animals contain larger
quantities of it.

Nitrogen is a transparent gas, without color, odor or taste.
It is distinguished for its negative properties, for it will neither
support life nor combustion, but appears to act simply as a di-
luent to the oxygen of the atnjos{)here. Its compounds, how-
ever, are among the most active and useful substances.

Nitric add, (NO^) commonly called aquafortis, is a com-
pound of nitrogen and oxygen. It exists both in the gaseous
and liquid state and is highly corrosive and active in its proper-
ties. In combination with potassa, forming nitre, and with other
alkalies, it is supposed to perform important offices in vegeta-
tion.

Ammonia is well known as hartshorn. It is composed of ni-
trogen and hydrogen, (NIP) and exists as a gas, but is rapidly

GERMINATION. 49

absorbed by water. In its pure state it is a powerful alkali, of
a caustic and burning taste, and pungent odor.*

It resembles water in the circumstance of being easily de-
composed in the vegetable organs. The alkahes are tested by
their turning vegetable blue c(>lors green. Acids are tested by
their inij)arting to the same vegetal)le infusions a red color.

With these definitions and descriptions the reader is prepar-
ed to attend to the sidjject of this section.

Germination. The development of vitality in the seed, or
germ, is called the process o{ germination^ by which process
the embryo is extracted from its envelopes, and converted
into a plant. The conditions necessary to excite the vitality
of the seed are three : access to moisture, to air or oxygen
gas, and to heat.

1. Moisture. Seeds which are fully matured and dry will
retain the vital power in an inactive state for a long time, if
no water is present, because this agent is necessary to facili-
tate the chemical changes which must take place, before it
can be called into action. The first effect produced by wa-
ter, is to penetrate the outer covering of the seed. The effect
is purely physical, and takes place equally well in the dead
and living seed. A grain of wheat, or corn, for example, de-
prived of its vital principle, will absorb water, and become
putrescent, while one which still possesses vitality will, by
imbibing moisture, develope a succession of new and living
powers. The second effect of water, is to yield oxygen to the
carbon of the germ, and form carbonic acid, which soon en-
velopes the seed. The decomposition of the water is effected
by the vital power of the seed. The hydrogen of the water
is supposed to combine with the oxygen of the air,' and form
water again. Few seeds, however, will complete the process
of germination, when wholly immersed in water, especially if
air is excluded ; hence the injurious influence of a very wet
soil, or a wet season, at the time of planting the seed.

* For a fuller description of the simple and compound bodies, see
Gray's Chemistry,

50 BIOLOGY OP PLANTS.

2. Ai?\ The oxygen of the air is an active agent in the
process of germination. Seeds will not germinate when
placed in a vacuum; in an atmosphere of carbonic acid, of
nitrogen, hydrogen, or of any other gas, which does not con-
tain oxygen. The principal .substance exhaled during the
process is carbonic acid. According to Liebig a small quan-
tity of acetic acid and ammonia are also formed during the
process. These gases form an atmosphere around the seed,
unless it comes in contact with water. The volume of oxy-
gen consumed is equal to that of the carbonic acid produced.
The oxygen of the air either combines directly with the car-
bon,* or with the hydrogen of the decomposed water ;t hence
this appears to be either a true process of decay, or of com-
bustion, and were it not for the vital force, the seed would
soon be separated into its original elements. As the oxygen
of the air is absolutely essential to germination, some have
supposed that the reason why seeds buried too deep, or in a
stiff soil, will not germinate, is that they are not reached by it,
and have inferred the importance of ascertaining the proper
depth for the different kind of seeds in order to facilitate the
process. On the same principle they account for the fact,
that after deep tillage, plants often make their appearance,
which have been cultivated upon the soil several years before.
But it should be remembered that seeds thus situated are also
deprived of other necessary conditions of which the absence
of the oxygen of the atmosphere is probably the least impor-
tant. Carbonic acid which is highly useful to the plant is
supposed to be injurious to germination by excluding the oxy-

* " The very first act of life in a seed is to evolve carbonic acid by
its carbon combining with oxygen of air, and its second act is to de-
compose water." — Dana.

t " Water is decomposed l)y their vital force ; and its oxygen, com-
bining with the carbon, forms carbonic acid." " Seeds have the pow-
er of decomposing water wliich causes the commencement of germi-
nation. ' ' — Lindiey.

GERMINATION. 51

gen of the air. Hence, as the acid is often produced in the
soil, in larger quantities than in the air, some have ascribed
the favorable influence of lime and alkalies upon germination
to the fact, that they absorb carbonic acid.

For a similar reason seeds should not be sown, or planted
in direct contact with green or fermenting manures, as the
process of fermentation evolves large quantities of carbonic
acid, in addition to that which the seed gives out in the pro-
cess of germination. This view has been given to explain
a fact which farmers have learned by experience, that when
green manures are placed in the hill, the corn planted upon
it, will not come up so well, as when the manure is spread,
and incorporated with the soil. But it is impossible to see
why the carbonic acid produced in this process should not
prove beneficial rather than injurious, for this acid is imme-
diately employed to decompose the rocks, and eliminate the
potash, or other alkalies, which are required to render the
food soluble, and fitted to be absorbed by the plant, the in-
stant its organs are sufficiently developed to receive it from
the soil. The more probable reason for the injurious effects
of green manures upon the soil is, that they impart too much
nourishment, and injure the plant, by yielding more food than
its organs, in this incipient state, can digest.

3. Heat. The third condition necessary to germination,
is a proper temperature. No seed has been known to ger-
minate at, or below the freezing point of water ; hence, seeds
do not germinate during the winter, although all other con-
ditions are supplied. The vital principle, however, is not al-
ways destroyed, but is developed on the return of spring,
when the temperature has arrived at the proper degree. The
requisite degree of temperature varies from 60° to 80° F.
The precise temperature depends upon the nature of the
seed, or plant. This accounts for the fact, that different
seeds germinate at different seasons of the year ; hence the
importance to the farmer of ascertaining the degree of tern-

62 BIOLOGY OF PLANTS.

perature requisite to the germination of the various seeds,
which are cultivated upon the farm ; hence, too, we see the
reason and necessity of green and hot houses, to produce the
requisite temperature for the germination of those seeds, which
are to furnish the earlier vegetables. Heat further promotes
germination, by producing those transform-ations which must
take place in the starch and gum of the seed, and which
both the external heat,, and that generated within the seed
duing the process, is employed in producing.

4. Light was formerly supposed to retard the process of ger-
mination, but according to the experiments of M. de Saus-
sure, it takes place in the same space of time, in the light as
in darkness, provided the light does not, by the heat contained
in it, dry up the skins of the seed ; but as this generally takes
place, the burying of the seed in the soil a few inches is
most favorable to the process, as the light is excluded, while
heat, moisture and air are freely admitted.

The process of germination then, and the changes which
take place, may be reduced to the following particulars.

L Water penetrates the coats of the seed, causing it to
swell, which facilitates the introduction of the oxygen con-
tained in the water, and in the atmosphere to all its parts.

2. The oxygen of the water thus introduced combines chem-
ically with the carbon which is the principal substance of the
seed, forming carbonic acid ; and the oxygen of the air with
the hydrogen of the water, forming water. The carbonic acid
acts upon the alkalies,* and these react upon the vegetable
matter and convert it into vegetable food.

3. The caloric necessary to the process increases the chem-

* When woody fibre or vegetable matter is brought into contact with
any alkali, it enters into a process of rapid decay, and is soon convert-
ed into a substance capable of being held in solution by the water, and
of entering the organs of plants. Jlence the use of potash, lime, etc.
in the process of germination, and during the growth of plants. Alka-
lies are powerful converters of vegetable matter into food.

GERMINATION.

53

Fig. 8.

ical action between the oxygen and the carbon, and tends to
volatilize the carbonic acid which escapes in the form of gas,
at the same time it excites the germ, and stimulates its devel-
opment.

4. By abstracting a portion of the carbon from the mucilage
and starch, of which the seed is mostly composed, a sweetish
milky substance containing sugar is formed, which is the first
nourishment of the embryo plant.

Here we may notice a very beautiful
provision ; the embryo rejects all nour-
ishment from the soil, but nature has
stored up in the seed itself, a most nu-
tricious substance, fully adequate to
all its wants. Fig. 8, h cJ, represents
the seed lobes containing the nourish-
ment of the embryo c a, with the fine
tubes which convey it to the germ.

The radicle c, Fig. 9, gives the first indication
of vitality, expanding and bursting its envelopes^
and at length fixing itself in the soil. The plum-
ula a, next unfolds itself, developing the rudiments
of leaf, branch and trunk ; finally the seminal
leaves gradually drop oflf, and the seed is converted
into a plant, capable of deriving nourishment di-
rectly from the soil, and from the atmosphere.

5. During this process, the gluten of the seed is partially
changed, and forms a substance called diastase. This sub-
stance appears to act an important part. It has the power of
transforming starch, first into gum, and then into grape sugar.
One part of diastase will convert 2000 parts of starch into
this substance. The necessity for this change, is due to the
insolubility of the starch ; on which account, it cannot enter
into the circulation. The diastase is, therefore, formed at
the point where the germ issues from the mass of food, and
converts the starch into a soluble form, that it may be easily

5

54 BIOLOGY OF PLANTS.

conveyed into the organs of nutrition. As soon as this stored
nutriment is exhausted, the diastase itself is transformed, and
enters into the plant.

6. ^rr^/r «f?'c? is also formed in the process. This is proved
by the fact, that when seeds are made to germinate in pow-
dered chalk, after a little while, acetate of lime may be wash-
ed out from it. This substance is very soluble in water, and
the agency of the acid according to Liebig is to combine
with lime and earthy substances, and convey them into the
roots of plants. But since the experiments of Braconnot ren-
der it probable that acetate of lime is injurious to plaAts, this
special function of the acid may well be doubted. It may aid
in converting cane sugar or starch into grape sugar, as it is
fully established that such changes take place, when these
substances are brought into contact with a dilute acid. When
the sprout starts up, the sugar, under the influence of light, is
converted into looody fhre. This does not take place until
the true or second leaf is expanded.

The period required for the germination of various seeds,
when the requisite conditions are supplied, depends upon the
nature of the plant, that is, upon the peculiar constitution or ac-
tivity of the vital principle. The vitality of some seeds, like that
of the smaller grains, peas, etc. are quickly excited ; those of
corn, and most of the vines require a longer period ; while the
stone fruits, and many of the nuts, require wrecks, and even
months, before they will indicate any signs of life.

The germination of seeds may be promoted by adding sub-
stances to them, either before, or after they are sown.

1. Immersing seeds in hot water has been found to pro-
mote germination. This is particularly desirable in the case
of parsnips, carrots and beets, whose vital powers are not
easily excited by the ordinary temperature and moisture.

2. Mr. Bowie states, that " he found the seeds of nearly all
leguminous plants germinate more readily, by having water
heated to 21)0°, or even to the boiling point of Fahrenheit's

GERMINATION. 55

scale, poured over them, leaving them to steep, and the water
to cool for twenty-four hours," and some seeds have germina-
ted readily, when boiled for five minutes. There is danger,
however, if the water is too hot, that the vitality of most seeds
will be destroyed.

3. By mixing seeds with substances wliich yield oxygen
readily, germination is promoted. Under ordinary circum-
stances, oxygen is furnished from the decomposition of water,
by the vital force ; but when this force is languid, the supply
of this agent from other sources is of the highest utility.
Humboldt employed a dilute solution of chlorine. which tends
to decompose the water, through its affinity for hydrogen, with
which it combines, and sets the oxygen at liberty.

Mr. Otto of Berlin employed oxalic acid, which exerted
such an influence upon the vitality, that old seeds which would
otherwise die, are made to germ.inate readily. In all these
cases, however, there is often danger of injuring the vitality
of the seed, by yielding too much oxygen, and, with a few ex-
ceptions, the ordinary conditions are the best for the purposes
of agriculture. The gardener may derive essential aid by em-
ploying these artificial methods of facilitating the germination
of his seeds.

Seeds seem to be the appropriate parts of the plant from
which a new individual is derived, and it appears to be the
great end of all the vegetable functions to mature and fit
them for this office. But although the seed is the principal
means of propagation, it is not the only mode ; propagation
may be effected by means of hulhs, buds and leaves. The ex-
citement of the vitality of bulbs and buds, depends upon the
same conditions, as that of the seed, although the chemical
changes are not so complicated. The power of propagating
plants, by any other means than by seeds, depends wholly up-
on leaf buds, (Fig. 7,) or upon what is technically called
" eyes ;" these are found on the bulbs, and on the stem of the
plant, where they are called buds. They are in fact rudimen-

56 BIOLOGY OF PLANTS.

tary branches, containing the elements of independent exist-
ence. Some of them fall off, as in several kinds of lily, and
take root, and form a new plant, while others remain attach-
ed to the stem or root.

Although all plants seem capable of being propagated by
eyes, only a few are actually produced in this way. The po-
tato and the vine are almost the only examples of the use of
eyes for this purpose, unless propagation by slips, by budding
and grafting, may come under this designation.

The development of vitality in the potato root is similar to
that of the seed. The eye corresponds to the germ, and the
bulb to the lobes of the seed. The matter necessary to sup-
ply the shoot with food, is treasured up in the bulb, just as that
is in the seed lobes which nourishes the germ of the seed.

An eye from a branch of the vine being cut off with a small
portion of the wood, and placed under the same conditions
with the seed or bulb, will soon throw out roots and branches.
The wood furnishes the nourishment required, before it can
derive it from the soil ; for if the eye has no wood attached to
it, life will not be supported, and it will die. Other plants
may be propagated in this way, but the buds and bulbs of most
plants possess too little vitality to be successfully employed for
this purpose. Many plants, however, may be easily propaga-
ted by small branches, called

Cuttings. When these are subjected to the proper condi-
tions of temperature and moisture, their buds give rise to new
individuals, capable of maintaining a separate existence.

Propagation hy layers is the same as the above, witli this
difference. A layer is a branch bent into the earth and half
cut through at the bend. When this has thrown out roots in-
to the soil, it may be separated from the tree. The Ficus
Indicus, in its natural state, propagates itself in this way.

Suckers are also employed for the propagation of plants.
They are sprouts sent up from the roots of trees and shrubs,
and make their appearance most frequently when the tree is

DEFINITIONS AND DESCRIPTIONS.

57

cut down, because the nourishment in the roots has nothing
to absorb it, and hence it forces up branches for this purpose.

In all these cases, as well as in those of budding and graft-
ing, the principle is the same ; " the vital points," are placed
under fitting conditions of air, moisture and temperature, and
they become converted into new individuals. Even the leaf
is capable of forming buds and of continuing the species ; each
according to the great law of organized beings, propagates its
own species ; and in all cases but one the same variety of the
species. The seed only preserves the same species.

The propagation of plants, by their pjg xq

several organs, shows the bountiful pro-
vision of nature to secure the continu-
ance of the species. The vital points
are the same, whether found in the
seed, bulb, bud or leaf The different
organs, as has been shown by Goethe,
are only developments of one simple
germ. The leaf buds, (Fig. 10,)
scales, blossoms, stamens, pistils, fruit
and branches are only a development
from one simple structure. The germ
is converted into roots or stems, or any other organ ; hence
we should expect to find the vital points or eyes in all the or-
gans, as they are, in fact, the same organ under different
forms, and are easily transformed into each other. We see
these transformations going on around us. In the cultivated
roses, the stamens become petals. In the pofentilla nepalensis
the flowers change into branches, and the sepals, petals and
stamens are converted into leaves.

Sect. 3. Definitions. — Conditions of the Growth of Plants.

1. Soil. Soil is decomposed or crumbled rock, mingled with
a certain portion of animal and vegetable matter, called humus,
or vegetable mould.

5*

58 BIOLOGY OF PLANTS.

2. Siih-soil. The sub-soil lies immediately below the soil, and
is mostly destitute of vegetable matter.

The parts of plants which are concerned in nutrition are the
root, stem and leaves.

1. Root. The root is that part of the plant Fig. 11.

which penetrates the soil. The following are
some of the different varieties of roots : tap
roots, as in lucern and clover ; spindle roots,
as in tlie carrot, parsnip and beet ; branching
roots, as in most forest trees ; fibrous roots,
as in the grasses and most annual plants ; creep-
ing roots, as in the strawberry ; tuberous roots,
as the potato, and bulbous roots, as in the
fleshy plants, the onion, turnip, (Fig. 11, a,) which are composed of
regular concentric layers of vegetable matter. Roots increase
in length by the addition of matter to their points. When this
matter is first added it is soft, and possesses the properties of a
sponge, to absorb the gaseous, or liquid bodies, which are pre-
sented to it. On this account the points b, are called sponge-
lets or spongioles. It is through these, that most of the nour-
ishment derived from the soil, is conveyed into the organs of
the plant. The roots are also supposed to excrete matter into
the soil, which having passed through all the transformations
it is capable of in its descent from the leaves, is now rejected
as unfitted to nourish the plant. The root is also supposed to
have the power of selecting those substances which the wants
of the Yjlant require, as the same species will absorb unequal
quantities of different substances wlien presented to them.
But the discriminating and excretory power has been doubted,
and these functions of the root are not yet fully established.

2. Stem or Culm. The stem (Fig. 12) is made up of bundles of
small tubes, extending from the roots to the leaves, in which sap
and air circulate. The bark coutains similar tubes for the de-
scent from the leaves of the cambium, or elaborated juices.
The stem contains the pith c, which consists of tubes disposed
horizontally, and forming by the medullary rays, a communica-
tion with the bark ; but so far as experiments have been tried
with colored solutions, the pith does not serve the purpose of
circulating the sap. The tubes of the wood aid the ascent of
the sap, which, in its progress upward, is sid)jected lo certain
chemical changes, and it is supposed by some that the various
gaseous bodies, which <ire in the wood, and ascend to the leaves,
are produced by transformations in the c>ap in its progress up-

DEFINITIONS AND DESCRIPTIONS.

59

ward. The vessels of the wood, Fig. 12.

like the roots appear to possess

the power of discrimination, as to

what substances they will receive.

When, for example, the trunks of

several trees, of the same species,

are cut off above the roots, and

immersed in solutions of different

substances, some of these solutions

will quickly ascend in the tubes,

and penetrate the entire mass,

while others will not be admitted

at all, or very slowly, by the vessels

of the tree. The functions of the

stem are performed mostly by the

alburnum, or sap-wood.

The branches or twigs are ex-
tensions of the trunk, as a h,
Fig. 12.

S. Leaves are still further extensions of the wood, and of the
bark. The fibres of the leaves are minute tubes of Avoody mat-
ter, connected with the w^ood, from which they receive the sap.
The green part of the leaf is an expansion of the bark. The
sap descends from this part into the bark, and thence to the
root. Hence, the leaf consists of two layers of veins or fibres,
covered by a thin membrane, (the epidermis,) which is an ex-
pansion of the outer bark. This membrane is filled with small
apertures, for the absorj)tion and transpiration of gaseous
and liquid bodies. These pores (stomata) on the upper surface
are supposed to exhale, and those on the under side of the leaf
to inhale substances. They will not absorb all bodies indis-
criminately, for they drink in oxygen, carbonic acid and water,
but reject the nitrogen.

4. The fiower-leaves are called petals, and perform the office
of inhaling and exhaling various substances; but they absorb
oxygen at all times, both day and night, and constandy emit
carbonic acid; while, during the day, the leaves absorb carbonic
acid and emit oxygen gas, and, during the night, reverse the pro-
cess. The flower-leaves also exhale odoriferous particles, the
nature of which, it is difficult to determine.

Although plants differ from animals in giving no signs of
perception and voluntary motion, yet in their organs and pro-
cesses of nutrition there is a striking analogy.

60

BIOLOGY OF PLANTS.

3. The stem and branches are the frame-work or skeleton, for
the support of the parts which are necessary to the processes
of nutrition.

2. The roots, in connection with the leaves, serve the pur-
poses of mouth and stomach, absorbing and digesting those sub-
stances, which are held in solution l)y water or air.

3. The common vessels are tubes, answering to the lacteals and
veins of animals. These tubes pass upward from the root
through the stem, and are distributed in minute ramifications,
over the surface of the leaves. Through these tubes the sap
or circulating fluid ascends.

4. The leaves are the lungs which perform the office of absorb-
ing and exhaling carbonic acid, oxygen, anunonia and water, by
which the sap is prepared for its descent and assimilation.

5. The proper vessels are tubes corresponding to the arteries of
animals, extending from the leaves through the inner layer of
the bark, to the roots. In these tubes, the prepared nutriment
descends, yielding, or forming in its progress, the peculiar sub-
stances which belong to the vegetable kingdom.

6. Finally. " The size of a plant is proportioned to the surface
of the organs which are destined to convey food to it." That is,
a plant obtains another mouth and stomach with every new fibre
of root, and every new leaf; hence, the size depends upon the
amount of the leaves and roots. If the leaves be plucked off,
the plant will either die, or become stinted in growth. If the
roots are diminished, a similar effect will be produced. It is
on this principle, that oaks are reared by Chinese gardeners,
both in Amsterdam and London, only a foot and a half high,
" although their trunks, bark, leaves, branches and whole habi-
tus evince a venerable age." As the leaves and roots are per-
mitted to increase, they absorb a greater quantity of jiourish-
ment. This is not returned to the soil, but is employed in
forming new organs.

The conditions required for the most vigorous action of
the vital principle, during the growth of plants, embrace
nearly the whole science of agriculture. But I shall confine
myself, in this place, to three conditions ; a proper medium
and space in which to grow, proper food, and proper tillage.
A general view only of these conditions can be given in this
connection, a more particular consideration of them will be
reserved for future sections.

MEDIUM AND SPACE FOR GROWTH. 61

I. Proper medium and space for groivth. In the process
of germination, the only conditions are air, water, and a cer-
tain temperature. But as soon as the roots and stalks make
their appearance, they require mechanical support, and a
medium for the action of those agents which are necessary to
their perfect development. This medium is the soil and the
atmosphere. The former only demands attention in this
connection. There are some aquatic plants that float upon
the surface of water and derive their nourishment from it, and
from the atmosphere; and a large number of parasitics, as
the mistletoe, which attach themselves to larger plants or
trees, and even to the rocks, such as the mosses, from which
they derive support and nourishment ; but all vegetables, cul-
tivated for the use of man, and other animals, require, as a
necessary condition to the most vigorous action of their vital
powers, that their roots should he fixed in the soil.

Uses of the Soil The soil appears to serve several pur-
poses in this respect.

1. It furnishes support to the plant, and prevents it from
being blown about by the winds. Different plants require
different kinds of soil to give the requisite stability. Wheat
requires a stiff soil ; corn a light one. This results, not only
from the different degrees of strength in the vital power, but
also from the character of the roots, and the weight which
the stalk must sustain. Those roots which lie near the sur-
face, like most of our common grains, require a stiff soil ;
those which penetrate deep, like most of the hoed crops, re-
quire a light soil in order to gain the requisite support ; hence
the importance of adapting the crop to the character of the
soil, or the soil to the nature of the root.

2. The soil is the repository of the food of vegetables, and
a medium of communicating it to their roots.

3. The soil facilitates the chemical changes, necessary in
the preparation of the food, and of those saline compounds,
which either act as a stimulus to the vital power, or are the

63

BIOLOGY OF PLANTS.

means of supplying some other agency necessary to the action
of the vital functions.

• It has been suggested, that there is produced, by the various
mineral ingredients of which soils are mostly composed, an
electrical effect, which facilitates the absorption of the food.
The soil, in connection with the living plant, is a galvanic
battery, not only acting directly upon the vital functions, but
also rapidly decomposing the soil itself

4. The soil also serves as a sponge to retain the requisite
supply of water. It retains the caloric, and permits a free cir-
culation of air ; all of which it distributes according to the
wants of the plant.

5. Finally, the soil serves to retain gasious proclucts, as
ammonia, which it yields up as the wants of the plant require.

Such being the important agency of the soil, it is of the
highest practical interest to the farmer, to ascertain its cha-
racter ; for all soils do not perform these functions with the
same degree of perfection ; hence the farmer, before he casts
the seed into the earth, should inquire, whether the soil is.
fitted to discharge those duties, which the peculiar constitu-
tion of the expected crop requires ; and he should not hope
for a bountiful harvest, unless this condition of the vital pow-
er is supplied. Proper attention to the soil is one of the se-
crets of successful farming. It is from this belief that I have,
in future chapters, devoted so large apart of the present work
to its formation, composition and improvement.

II. Food. The second condition required for the most
vigorous action of the vital principle, during the grov.th of
plants, is proper food. We have noticed the beautiful provi-
sion of nature, by which a supply of food is stored up in the
seed or bulb, for the support of the germ. This portion, how-
ever, is small, and when it is exhausted, food must be supplied
from some foreign source, from the atmosphere, the water,
and from the soil ; or the vital power, having nothing to act
upon it, and sustain it, will be destroyed. Hence proper nour-

FOOD OF PLANTS. 63

ishment is equally necessary to the growth and perfection of
a plant, with that of an animal, and the effect of proper or
improper feeding is no more visible in the one case, than in
the other. The animal and the plant are alike dependent
upon foreign matter, not only for their growth, but for exist-
ence itself. It may be stated, then, as a general law, that

All vegetables must have a supply of food, in quantity and
quality, suited to their age and character.

1. The supply of food must be constant. Plants differ
from animals in this respect ; the latter require it at stated
times, with considerable intervals between ; while the former,
owing to their organs of nutrition, must have a constant sup-
ply, at least, during the period of growtli. Perennial plants,
however, in cold climates, are capable of resting for several
months without drawing any nourishment from the soil ; and
in this respect, they resemble those animals which are torpid,
during the same period.

2. The supply of food must be properly regulated. If too
much nourishment is added at any one period of growth, the
organs will become clogged, or the plant will attain a rapid,
but sickly growth. This is the case, when seeds are planted
in fermenting or green manures, and when plants grow upon
dung-hills ; hence the reason for incorporating the manures
intimately with the soil. If too little food is supplied, the
plant will languish, and its productions will be scanty, and of
an inferior quality.

The most important rule on this subject is to graduate the
nutriment, according to the wants of the crop, at each succes-
sive stage of its growth. During the process of germination,
no foreign matter is needed. The young plant, as soon as its
leaves have become fully expanded, derives most of its matter
from the atmosphere. It is during the maturing of the fruit
or grain, that plants derive most nourishment from the soil.
This is supposed to be partly due to the fact, that the leaves
and stalks, previous to the formation of the fruit, have their

64 BIOLOGY OF PLANTS.

organs of absorption in a most vigorous state, but, at that pe-
riod, the pores are partly closed up, and the nourishment
must pass in at the roots ; and partly to the kind of nourish-
ment which the soil alone is capable of furnishing. Hence,

(1) In the application of manures, we may derive, from
the above facts, the most important practical rules ; the kind
and quantity depending upon the time when the crop matures
its seeds. If the crop is winter rye, or any of the smaller
grains, which mature their seeds in July or August, green
manures should not be applied, because the process of fer-
mentation yields abundance of carbonic acid, which power-
fully stimulates and increases the stalks and leaves, but is in-
jurious to the formation of the grain. This process will be
most active when the kernel of early grains is maturing, and
the appropriate nutriment, which goes to the seed, will not
then be prepared in the soil ; hence there will be abundance
of straw, with but little grain. But if the crop ripens its seed
in September, like corn and most hoed crops, green manures
are far preferable, because the fermentation will be most ac-
tive, when the stalks and leaves require its influence, and
the nutriment, which is formed in the soil, by this process,
will be ready for the formation of the grain, by the time the
seed requires it.

(2) The above facts explain the reason why crops exhaust
the soil more when permitted to mature their seeds, than when
cut green ; hence, crops cut for fodder, as grass, should not
be left to mature their seeds, in consequence of their exhaust-
ing effects upon the manures in the soil ; hence, too, the utility
of ploughing in green crops, because food is thus taken from
the atmosphere, and added to the soil,

(3) Finally, from the same principle may be inferred the
utility of " soiling," that is, of keeping farm stock on green
crops, during the summer season. The green crops, deriving
their support mostly from the atmosphere, exhaust the soil but
little, while their conversion into manure in the stables, adds

NATURE OF FOOD. 65

directly to the means of fertility, of securing greater abundance
in future harvests.

3. The kind of food must be such as the vital forces of the
plant can assimilate ; such as lis peculiar constitution requires.
The nature* of the food of plants has been a subject of much
conjecture and controversy. Lord Bacon believed it to be
water ; Tull and Du YidJueX, pulverized, earth ; Hunter, oil and
salt. But the investigations of modern chemists, have thrown
much light on this subject, although some things are not yet
settled. It now appears, that the food of vegetables, like that
of animals, consists of several substances ; that it is derived
from numerous sources. The principal substances regarded
as food,t are carbonic acid,| ammonia, water, and several or-
ganic substances which form the constituents of vegetable
mould, and alkalies, alkaline earths, metallic oxides and seve-
ral salts.

The vegetable mould, according to the analysis of Ber-
zelius, consists of several compounds of carbon, oxygen, hy-
drogen and nitrogen, called humin, humic, crenic and apocre-
nic acids. The humic acid has been called geine. These
substances are combined in the soil, in part, with alkalies and
oxides, and constitute the principal food which plants derive
from that source.

But different species of plants require different kinds of
food, or require it in different quantities. Plants which
contain a large quantity of nitrogen, must be supplied with

* The full consideration of this subject will be deferred to a future
section, on the source and assimilation of the simple bodies which en-
ter into the composition of plants.

t Nutritive matters are, correctly speaking, those substances which
when presented from without, are capable of sustaining the life, and
all the functions of an organism, by furnishing to the different parts^
of plants, the materials for the production of their peculiar constituents.
— Liebig.

X For a description of these bodies, see second and third chapters.

6

^ BIOLOGY OF PLANTS.

food containing that substance, in a form in which they can
assimilate it, as in ammonia, nitric acid, crenic and apocre-
nic acids. Some plants, as wheat, require potash and phos-
phates. All kinds of grasses require silicate of potash. Sea-
plants require soda. And, generally, plants require differ-
ent substances to enable them to develope their organs. So
also wheat requires more alkalies in quantity than barley or
oats. Saussure found that wheat requires different quantities
at different periods of its growth. The same fact has been
observed of other plants.*

The absolute necessity of supplying plants with appropriate
nourishment, of nutriment derived from animal and vegetable
manures, has been proved, by the most carefully conducted
experiments, whatever be the particular form in which the
food is presented, whether as carbonic acid, water, ammonia
and saline compounds, or, in addition, as geates or humates,
crenates and apocrenates. A continued course of cropping
will exhaust the soil, both of vegetable matters and salts, and,
unless they are restored, it will become in time, wholly bar-
ren ; and in proportion as these matters are wanting, or in a
state unfitted to enter the organs of plants, will the soil become
sterile, its productions scanty, and of an inferior quality.

3. Tillage. The third general condition necessary to the
growth of plants, is proper tillage. The object of tillage, is
to break up the entire soil, and give it such a degree of fine-
ness, as to render it permeable to atmospheric agents and wa-
ter, and to incorporate the manures with the soil ; thus to pro-
mote an equal and economical distribution of food to the roots
of plants ; to bury the seed at the proper depth ; and finally, to
destroy weeds, which rob the crop of food, and check its
growth.

( 1 ) The soil should be thoroughly 'ploughed ; every part of it
turned over and stirred at a sufficient depth to allow the roots
of plants to extend themselves freely in every direction. If

* For a further notice of this subject, see third chapter.

PROPER TILLAGE 67

this is not done, if the furrow is wider than the plough can
turn, the parts not broken up will obstruct the roots, and pre-
vent the free circulation of air and water. The water, set-
tling in the creases of the furrows on the sub-soil, will form al-
ternate wet and dry ridges, which will injure the delicate parts
of the roots. When the soil is only partly broken, but a small
part of it is brought to bear upon the roots, and hence the
nourishment is withheld from the crop.

(2) The soil should he deeply ploughed. This is especially
necessary for root crops, and highly useful for any crop, pro-
vided sufficient manure is added. Ten inches of tillage depth
are far preferable to six inches, because the former depth will
keep the soil drier, and render it capable of being cultivated
much earlier. Such a depth renders the soil less subject to
drought, in consequence of furnishing a larger stratum, pos-
sessing the properties of a sponge, to absorb the water and re-
tain it for the wants of the plant. Such a soil will be a better re-
tainer of heat ; and will furnish a better medium for the ac-
tion of chemical and other agents, which are necessary to the
most vigorous growth of vegetables.

The experiments of Baron Von Vought, upon the estate
of Flottbeck, Germany, fully establishes the utility of deep til-
lage. After making thousands of experiments during thirteen
years, he came to the conclusion, that a tillage depth of from
ten to fourteen inches was vastly preferable to a less depth.
And Von Thaer estimates the value of soils, with a flat and
deep mould, in the following proportions. If with a cultiva-
ted soil three inches in depth, the land is worth thirty-eight
dollars per acre, that of five inches will be worth fifty-six dol-
lars ; that of eight inches will be worth sixty-two dollars, and
that of eleven inches, seventy-four dollars. Each inch of
mould between six and ten inches, increases the value eight
per cent.

The importance of deep tillage may be inferred, from the
fact, that some plants, as lucerne and sainfoin, are said to have

OO BIOLOGY OF PLANTS.

penetrated the soil, to a depth of thirty feet, and that the tap
roots of clover and some other plants extend to a depth of
three feet or more.

(3) The soil should be finely pulverized; especially the
surface to the depth of six inches ; in order that the seed corn,
grain, or potato shoot may be placed in earth finely divided,
into which the tender fibres of the root may easily and quick-
ly shoot, and air, water and heat operate with facility.

If the soil is lumpy, large pores or intervals will exist,
across which, the delicate fibres of the roots will extend them-
selves, become exposed to injury, and unable to discharge
their functions in a vigorous manner.

Professor Hitchcock accounts for the superior fertility of
the alluvial soils of New England, on this principle. Such
soils do not contain so large a quantity of vegetable matter as
those less fertile, but their materials are in a much more fine-
ly divided state, and hence their fertility. This condition
of vitality is liable to be disregarded by the farmer, because
the expense of preparing the soil, in the first instance, is much
increased, and because the time of sowing and of harvesting,
are too far removed to impress the mind with its necessity
and utility, i c j

(4) The. soil should he covered at the proper depth. The
requisite depth varies according to the nature of the seed, but
generally the smoother and finer the surface, the less the depth
required. Grain covered one fourth of an inch in depth by
finely pulverized earth, where it will feel the influence of heat,
moisture and air combined, will be much more likely to ger-
minate, the vitality will be much sooner excited, the roots
will become more powerful and the stalks, leaves and fruit
much more abundant.

The Baron Von Vought has made a numerous collection of
plants, in which the seed was, in the one case, covered only
two lines in depth, and in the other a little more than one inch
and a half ; and these plants show, " what a striking differ-

PROPER TILLAGE. O^

ence there is in the vital germ lying on the surface where
roots and leaves, immediately, numerously and powerfully
shoot forth from one point, and the weakened vital germ, ly-
ing at the depth of 1.680 inches, shoots forth few roots, but a
thin tube, which rises as far as the surface, where a knot is
formed whence the weakened germ pushes forth a single and
sickly plant."

Some seeds require to be covered only by a bush-harrow.
The seeds of grain-crops, and of some garden vegetables may
be covered in this way, but hoed crops require a greater depth.
The requisite depth depends also on other circumstances —
the character of the soil, and its state of moisture or dryness.
Hence farmers should adapt their mode of tillage to these cir-
cumstances, if they would derive the highest benefit from this
part of culture.

(5) Finally. The soil should be kept free of weeds. The
reason for this is, that the weeds exhaust the soil as much as,
if not more than the crop, and especially in the dry season, ab-
stract from the soil the moisture required for the grain. In this
latter respect, weeds with large leaves and stems, will take up
through their roots and transpire through their leaves, their
weight of moisture in twenty-four hours. The vital functions
of the crop are thus enfeebled or destroyed, while the ruthless
weeds fatten upon the provisions which were designed for the
rightful inhabitants of the soil. There is no doubt but that
many a crop has been diminished one quarter, one third and
even one half by the weeds which have been allowed to seed
and spread themselves on the land.

The conditions of the growth of plants as presented in this
section are very general, they will be more fully expanded
in succeeding parts of the work.

These general conditions of life, however, should be im-
pressed upon the mind of every farmer, if he would aid the
vital power in the growth of his crops. He must supply his
plants with the proper medium and support ; with soil fitted

6*

70 BIOLOGY OF PLANTS.

to the nature of the plant; with food, in kind and quantity ^
suited to the age and wants of each species, and with proper
tillage. Especially must he exterminate those natural foes,
which make their appearance during the summer months, and
which may easily be overcome if attacked before they have
obtained a firm footing on the soil ; but let him remember,
that they possess a wonderful fecundity, and, like a certain
animal, have many lives, they must, therefore, be made to die
many deaths, before they can be completely exterminated.

The importance of supplying the conditions, for exciting
the vital principle of seeds, and for its most perfect action
during the growth of plants, may be illustrated by reference
to the mechanic arts. In all these arts there is some agent,
natural or artificial, employed as a moving power.

1. In locomotives and steamboats, the main spring of the
whole movement is the expansive force of steam, when sub.
jected to a high temperature. But steam has no power unless
supplied with the appropriate conditions. If made in the open
air it will not move a steamboat, though it may a feather. If
simply confined in a boiler, it will manifest its power in no way
unless it be to break from its confinement, and gain its free-
dom. A complicated apparatus must be supplied, the result
of intense study, and multiplied experiment, before its power
is available for any useful purpose ; and finally, various other
conditions must be added, before it will propel us across the
land or the ocean.

2. In most cotton and woollen factories the moving force is
water. This power also requires several conditions, before
it can be usefully applied. The force of running water,
though often very great, will not manufacture cotton and wool-
len cloths. If it is arrested in its progress to the ocean, its
force will only be exerted upon the sides of the dam. Fac-
tories must be erected, wheels of the proper size and form
must be constructed. There must be added a complicated
apparatus of cards, spindles and looms, and after all this, cot-

VITAL AND PHYSICAL AGENTS. 71

ton or wool must be supplied, and workmen who understand
the operation of the machinery, before the beautiful fabric is
wrought and fitted to adorn our bodies, or to protect them
from the vicissitudes of the seasons.

Steam and water are the great agents in these processes,
but they are not the only agents, nor will they avail us unless
the necessary conditions are supplied.

The vital power is much more wonderful and useful in its
operations, than any of the agents of dead matter ; but it will
not exert its force without its conditions, any more than steam
and water. When its conditions of activity are supplied, its
productions in their variety, beauty and utility, exceed those
of all other agents of the natural world. This power supplies
the manufacturing arts with nearly all their raw material, and
is emphatically the sustaining cause, in the hand of the Deity,
of the present order of nature.

If it is important, then, that the mechanic and artizan should
spend years of study and labor to supply the necessary con-
ditions for the exertion of steam and water power, is it not
vastly more important, that the farmer should carefully study,
and faithfully supply the appropriate conditions for the exer-
cise of the vital power, that he may avail himself of its more
valuable and indispensable productions. What engineer would
expect to run steamboats and locomotives, with nothing but
fire and water ? What manufacturer could hope to spin and
weave by the mere force of hydrostatic pressure ? Or what
mechanic of any trade, would expect to produce a beautiful
and useful material, without carefully attending to the condi-
tions which are required for its production ? Why, then,
should the farmer expect a bountiful harvest, if he neglect to
supply the conditions required for the activity of the vital
power in the production of his crops ?

In agriculture, as in the mechanic arts, we need the influ-
ence of example. We need some few farmers, in every portion
of the country, who shall present living examples to all around,

72 BIOLOGY OF PLANTS.

of the possibility and utility of supplying these conditions of
vegetable life.

It is on this account that I would urge upon the young far-
mer to study this subject, to obtain a scientific knowledge of
it, that he may be able to exhibit a practical application of the
principles here suggested, when he settles down to the great
business of life.

CHAPTER II.

INFLUENCE OF THE ATMOSPHERE, WATER AND OTHER
AGENTS UPON THE VITAL PRINCIPLE AS CONNECTED
WITH THE PHENOMENA OF VEGETATION.

Some of these agents have already been alluded to when
treating of the vital principle, considered as the principal
cause of vegetable productions. It is proposed now to con-
sider more particularly the degree in which they favor or re-
tard the process of nutrition, with the mode in which they act,
in order more fully to explain the philosophy of the subject,
and to point out suitable methods, to be employed by the ag-
riculturist in the culture of his crops. These agents are
the atmosphere, water, gravity, cohesion, affinity, heat, light,
electricity, and the agency of man.

Sect. 1. Agency of the Atmosphere.

The atmosphere is that gaseous fluid which surrounds the
earth, and extends to a distance of forty or forty-five miles
above it. It is composed essentially of oxygen and nitrogen
in the proportion of 21 parts of the former, to 79 of the latter
in 100. The atmosphere also contains variable quantities of
watery vapors, ytj^uiy part by volume of carbonic acid, a
smaller quantity of ammonia, and several other gaseous com-

INFLUENCE OF THE ATMOSPHERE. 73

pounds, such as hydrogen, nitric acids, sulphureted and car-
bureted hydrogen. It is also probable that odoriferous, sa-
line, and metallic particles float in it ; all of which, save the
first, are found in exceedingly small quantities. The agency
of the atmosphere may be studied under the following heads.
Influence of its oxygen, of its nitrogen, of its ammonia, of its
nitric acid, of its sulphureted hydrogen, of its carbonic acid,
and its mechanical agency.

I. Injluence of the oxygen of the air in vegetation. We
have seen, that oxygen is a most important agent in the pro-
cess of germination, combining with the hydrogen of the de-
composed water, and with the carbon of the seed, and that
carbonic acid is almost the only gaseous product evolved.

Oxygen is no less necessary to the growth of plants.
This is proved by the fact, that when all other conditions are
supplied, if the plant is deprived of oxygen it will wither and
die ; hence, when the roots of trees are surrounded with
stagnant water, no oxygen being supplied to them, the leaves
turn yellow and fall, but when fresh water is added, yielding
the requisite quantity of oxygen, the tree will revive.

Oxygen acts principally upon the roots and leaves oi plants-
The mode of its action in the roots has been differently rep-
resented by different chemists. There are four theories. 1.
The absorbed oxygen combines with the carbon of the plant.

2. It combines with the hydrogen of the decomposed water.

3. It is assimilated. 4. It combines with substances in the
soil by which food is prepared.

First theory. The roots absorb oxygen and convert it by
means of their carbon into carbonic acid. The truth of this
theory is supposed to be proved by placing fresh roots depri-
ved of their stems under a bell-glass receiver. They will di-
minish the quantity of air, by abstracting its oxygen, and
forming carbonic acid. The volume of oxygen consumed is
never greater than the bulk of their roots.

Place the roots thus saturated with oxygen in a receiver

74 BIOLOGY OF PLANTS.

of air, and carbonic acid will be given off without altering
the volume of the air ; but if they are placed in the open air,
they will absorb a volume of oxygen equal to themselves, as
in the first instance ; hence, the atmosphere abstracts the
carbonic acid which the roots form.*

If the roots are connected with the stems and leaves, they
will constantly absorb oxygen, and the quantity will amount,
in time, to much more than their volume, because the carbon-
ic acid which they form passes into the juices, ascends to the
leaves, where it is decomposed by the action of light, or tran-
spired with the water, if the plant is in the shade ; hence, they
never become saturated. But these facts are equally well ac-
counted for on other theories.

Second theory. The oxygen of the air, which is absorbed
by the roots, combines with the hydrogen of the water, which
the vital power decomposes, while the oxygen of the decompo-
sed water combines with carbon and forms carbonic acid ;
hence, the agency of the oxygen of the air is to keep up the
supply of water.

Third theory. The oxygen thus absorbed by the roots, is
directly assimilated to the vegetable products, or, if any chan-
ges take place, the oxygen is neither converted into carbon-
ic acid by combining with the carbon, nor into water by unit-
ing with the hydrogen of the decomposed water. These
changes may take place, but the theory supposes that the oxy-
gen in some forin is assimilated to the vegetable organs.

Fourth theory. It is possible, however, that neither of
the above theories explain the reason of the necessity of oxy-
gen to the roots of plants, in order to promote their growth.
The oxygen of the air effects changes upon the humus of the
soil, in preparing the food, and this may be the reason for its
influence.

But whatever view is taken, the agency of oxygen upon
the roots of plants, explains the reason why the earth must be

^ Chaptal.

INFLUENCE OF THE ATMOSPHERE. 75

Stirred about them. The oxygen of the air is thus either
brought into direct contact with all parts of them, so as to
answer the conditions of some one of the above theories, or
else it is thus brought into contact with the humus, and pro-
motes its decay and conversion into vegetable food.

The leaves of plants also absorb oxygen from the atmos-
phere, especially during the night season, and sometimes in
the shade, at the same time they transpire carbonic acid, and
the volume of carbonic acid thrown off, is just equal to that
of the oxygen consumed. The changes which take place in
this process are also subjects of theory, although it is pretty
well established that the last of the three following is the true
one.

First theory. The oxygen, absorbed by the leaves, enters
into combination with the carbon, formerly introduced into
the sap of the plant, and there being no light to decompose
the carbonic acid thus formed, it is exhaled, or given back to
the atmosphere. This is precisely the change, which is sup-
posed by some to take place in the lungs of animals, and is
a true process of respiration. Some of the oxygen however
must remain uncombined in the juices, as the amount of
Jg part of the quantity absorbed can be disengaged from the
plant by means of heat.

Second theory. The oxygen which is absorbed by the
leaves, enters into combination with the hydrogen of the wa-
ter which the vital power decomposes, in the same manner
as when introduced into the roots. So that water is decom-
posed by the plant, its oxygen assimilated, while at the same
time, the hydrogen combines with the absorbed oxygen, and
forms water. This, however, is a very doubtful theory of
these changes, though a possible one.

Third theory. The oxygen thus absorbed, combines with
the vegetable substances in the leaves. This appears to be a
purely chemical process, as it takes place equally well in the
dead, as in the living plant. If the substance of the leaves

76 BIOLOGY OF PLANTS.

is known, " it is a matter of the greatest ease and certainty to
calculate which of them, during life, should absorb most
oxygen by chemical action when the influence of light is
withdrawn." The oxygen in this casecombines with the vol-
atile oils, and changes them into resins, in some cases, while
in others, it unites with the constituents of nut-galls, and
forms acids, or with substances containing nitrogen.

The carbonic acid in this case is derived from the sap ; it
enters the roots with the water, and when it arrives at the
leaves it is not decomposed, but is transpired along with the
water ; this, of course, is purely a mechanical process, and
the quantity of acid will depend on the quantity of water.
The absorption of the oxygen and the emission of carbon-
ic acid have no connection therefore with each other, or
with the process of assimilation. A cotton wick, in a
lamp filled with water, saturated with carbonic acid, acts pre-
cisely like a plant in the night ; water and carbonic acid are
sucked up, and evaporated from the wick.

The quantity of oxygen absorbed by plants depends upon
their vigor, degree of heat, and the nature of their leaves.

1. The more vigorous the plant is, the greater the quantity
of oxygen which it is capable of absorbing during any given
period. This we should expect, because all the vital forces
are more active, and hence the growth must be more rapid,
and require a larger supply of the appropriate nutriment.

2. The same species of plants will absorb more oxygen at
a temperature of 88° F. than at 55° or 56° F.* This quan-
tity will therefore depend upon the season of the year and
upon the climate.

3. The leaves of different plants do not consume the same
quantity of oxygen gas, at the same temperature, and seasons
of the year. The quantity varies from a little more than one
half the bulk of the leaves, to eight times their volume.

The fleshy-leaved plants absorb the least oxygen, and re-

* Chaptal.

INFLUENCE OF THE ATMOSPHERE. 77

tain it with great force, (probably because they emit little or
no carbonic acid). The various species of these plants, ac-
cording to the experiments of Saussure, absorb during the
summer months, jfrom 1 to 1.7 of their bulk of oxygen ; hence,
such plants will flourish on high mountains, where the air is
rarified, and on arid sands.

The leaves of evergreen trees are next in order, as they ab-
sorb more oxygen than the fleshy-leaved plants, and much
less than those trees which lose their leaves during the win-
ter. The quantity in this class, varies during the months of
May and June from 1.5 to four times their volume, and dur-
ing the month of September from 0.86 to 3 times their
volume.*

Of the herbaceous plants^ those which grow on marsh-
es and bogs, absorb but little oxygen gas. This may be
due to the fact, that they are surrounded by an atmosphere
of vapor, or of carbonic acid, which does not render the in-
troduction of oxygen necessary. The quantity in such plants
under similar circumstances varies from 0.7 to 2.3 times
the volume of the leaves, while the leaves of herbaceous
plants not aquatic, absorb from 0.66 to 5 times their vol-
ume.

The leaves of those trees which are nailed during the win-
ter, as the oak, maple, and most fruit trees, absorb the larg-
est quantity of oxygen, and contain the most carbon. This
seems to depend upon the nature of the substances formed in
the leaf; thus the tasteless leaves of the Agave Americana ab-
sorb only 0.3 of their volume in the dark during twenty-four
hours; those of the oak containing tannic acid, fourteen
times as much ; and the balmy leaves of the poplus alba twen-
ty-one times that quantity. The large quantity of oxygen,
absorbed by these plants, may, also, be partly due to the fact,
that they not only supply nourishment for the purposes of veg-

Thompson's Chemistry, Organic bodies, p. 999.

7

BIOLOGY OF PLANTS.

etation during the summer, but store up large quantities for
the use of the plant, before it can derive it from a foreign
source in the spring. This process has been compared to
torpidity in certain animals, which store up a quantity of fat
in the autumn, from which they are nourished during their
winter slumbers. But the analogy is very slight, while the
chemical changes are quite different. The fat in the animal,
appears to combine with the oxygen in the lungs, a process
resembling the burning of a candle, by which the fat is slow-
ly consumed ; but the starch, which is laid up in the organs
of the tree, is converted into sugar, and in the spring is as-
similated. The process of assimilation is only delayed, until
the leaves are put forth, while in animals, no assimilation of
the stored matter takes place ; it simply burns out.

The quantity of oxygen absorbed in all these cases must
also depend upon the fertility of the soil, and the quantity of
the gas contained in the air by which the plant is surrounded.

The other parts of plants, such as the wood, petals, and
all those parts which are not green, absorb but a small quanti-
ty of this gas which is generally retained.

The action of oxygen, according to the experiments of
Saussure, upon the fruit, during the progress of growth, is pre-
cisely similar to that upon the leaves. Fruits absorb oxygen
during the night, and give it off during the day. But the ex-
periments of Berard seem to indicate a different process, during
the ripening of fruits ; oxygen being absorbed, and carbonic
acid given off, both in the sun, and in the shade. This is
doubtless true ; for it is found, that green fruits, fully grown,
will not ripen in atmosphere deprived of oxygen, but will com-
mence the process on its admission, provided they do not re-
main deprived of it too long. Hence fruits may be preserved
through the year, by surrounding them with an atmosphere of
carbonic acid, or by excluding the air. By the process of ri-
pening, the animal matter, woody fibre, malic acid and water,
are diminished, and the sugar is increased. This would be

AGENCY OF OXYGEN. 79

the effect of absorbing oxygen, and giving out carbonic acid.
When the fruit decays, it gives out large quantities of car-
bonic acid. The carbon is furnished by the substance of the
fruit, the oxygen from the decomposition of water ; the same
changes which take place in the decay of woody fibre, or any
other vegetable body.

From this view it appears, that the principal agency of the
oxygen of the air in the process of nutrition is,

1. According to the views of Thompson and ether chemists,
to combine with carbon, and form carbonic acid. This change
takes place both in the soil, and in the living plant. In the
soil, mostly by the fermentation of manures, or vegetable sub-
stances ; and in the tree, by uniting with the carbon which
has been previously introduced, forming carbonic acid ; this
with that contained in the soil and air, and which enters the
vegetable organs \u solution, is conveyed to the leaves, and
decomposed by the influence of light ; the carbon being re-
tained or assimilated, and the oxygen sent out to combine
with fresh portions of carbon, ready again to pass through the
same process.

The oxygen which is absorbed by the leaves and roots, is,
for the m.ost part, transpired into the atmosphere ; but a part
is retained, and aids still farther, by its various combinations,
the growth and perfection of the plant. Or,

2. According to Liebig, the oxygen of the air combines
with the vegetable products, by Rpurelt/ chemical process, and
aids the plant in the formation of several vegetable bodies,
while the oxygen which plants emit is derived from water
and carbonic acid, which are decomposed in the process of
assimilation. This is the more probable theory. But what-
ever view we take of it, whether the oxygen is derived from
the air, or the water ; whether it combines in the vegetable
organs with carbon, or is directly assimilated, it appears to be
an indispensable, but subordinate agent, to the vital power,
forming, by its combinations, those compounds which this

80 BIOLOGY OP PLANTS.

power uses for the purposes of the vegetable economy ; and
yet, so controlled by it as to change the order of its affinities,
and the character of the substances, of which it forms a part,
in the vegetable kingdom.

Oxygen exerts an equally important agency upon soils and
manures, combining with the metals, and forming oxides and
acids, which, by their union, compose the soil ; and effecting
changes in the vegetable matter of the soil, especially con-
verting insoluble into soluble food. This agency will be fur-
ther illustrated in a future section.

II. Influence of the Nitrogen of the Air. All plants, in some
of their organs, contain nitrogen in combination with other
substances, but do not probably derive it directly from the at-
mosphere. Although nitrogen seems necessary to the process
of vegetation, we do not know what agency that which is
contained in the air exerts, unless it acts, simply, as a dilu-
ent to the oxygen. A small quantity of nitrogen is absorbed
by the organs of plants, and given out again in an unaltered
state.

III. Ammonia of the Atmosphere. That the atmosphere
contained ammonia, in small quantities, every chemist well
knew ; but it was first proved, beyond a doubt, by Liebig,
who has calculated its probable amount, both in the air, and
in rain water. A pound of the latter contains from one quarter
to one grain of this gas. Hence there would fall, on the sur-
face of an acre, more than eighty pounds of ammonia, annually.
The ammonia of the atmosphere, owing to its great solubil-
ity, is brought to the earth by every shower of rain, and h^ce
must enter the organs of plants.

Ammonia is also found in the soil, in clays, in oxide of
iron, and in several other bodies, which must have derived it
from the atmosphere. Liebig and Dr. Wilbrand found it in
maple sap, the juice of the birch, and of beet root. How is the
atmosphere supplied with this substance ? This question is
easily answered by reference to changes in progress on the
surface of the earth.

AMMONIA OF THE ATMOSPHERE. 81

1. TJie putrefaction of animal substances is always attend-
ed by the revolution of ammonia, as a gaseous product. The
nitrogen which animals contain, is separated, mostly, in this
form.* In the decay of plants also, ammonia is given off.
The quantity thus formed, is very great. " A generation of
a thousand million men is renewed every thirty years, thou-
sands of millions of animals cease to live, and are reproduced
in a much shorter period."

The ammonia, thus produced, is partly thrown off into the
atmosphere, and partly retained in the soil in the form of
salts, or condensed in the pores of the humus, clay, water, or
other ingredients of the soil. Some of it enters the roots of
plants, a large portion is washed into the sea by rivers, or
carried there in rains. A part of that which remains in the
atmosphere is liable to be decomposed by thunder storms, so
that but a small quantity of that which is derived from this
source, exerts any agency upon vegetation.

2. When vegetable substances which contain no nitrogen
decay or are oxidized in the open air, they exert a catalytic
force upon the nitrogen of the atmosphere and the hydrogen
of the plant, and ammonia is formed in considerable quantities.

In a similar way, also, when inorganic substances suffer
oxidation in air or water, ammonia is formed ; thus Faraday
found, that when oxides were decomposed by potassium in the
air, this gas was evolved ; and Chevalier produced it by ex-
posing moist iron filings to the influence of the atmosphere.
The action of nitric acid on metallic oxides often produces it.

3. But the most abundant source of ammonia has been
pointed out, I believe, by Daubeny. In volcanic districts im-
mense quantities are evolved. This is formed in the interior
of the volcano by means of heat and the decomposition of wa-
ter, the hydrogen of which unites with the nitrogen of the air.
This explanation is rendered evident by a very simple exper-

* In hot countries, the ammonia of fermenting dung heaps, is part-
ly transformed into nitric acid.

7*

5531

82 BIOLOGY OF PLANTS.

iment ; thus, if a current of moist air is passed over red hot
charcoal, carbonic acid and ammonia are readily formed ;
hence it is easy to see, that the atmosphere must be constant-
ly supplied with variable quantities of this gas.

What then is its influence in vegetation ? A full considera-
tion of this agency will be reserved to a future section. It is
sufficient to remark here, that it is supposed,

1. To yield nitrogen to gluten and to vegetable albumen. It
is supposed to enter the vegetable organs either in a pure
state, or in the form of some of its salts, and, by various trans-
formations, to yield its nitrogen and perhaps its hydrogen, to
the formation of vegetable substances.

2. To stimulate the organs of plants and enable them to
obtain a larger quantity of the substances of which they are
composed. But as plants have no nerves, such stimulating
effects have been doubted by many. The fact, however, that
light, heat and electricity, produce effects upon the functions
of vegetables, analogous to stimulants, shows that there is no
good reason for doubting, that ammonia and other substances,
may exert a similar influence. Liebig thinks that no such ef-
fect is produced, and accounts for the powerful influence of
ammonia, on the principle of its yielding nitrogen, an essential
constituent of vegetable organs. But Berzelius is of opinion,
that such stimulating effects are produced, and that ammonia
.may act in this way.

3. But the most important action of ammonia is its influ-
ence upon the vegetable matter of the soil, and upon the sili-
cates. It causes by its presence or catalytic power the decay
of woody fibre, and renders insoluble geine, soluble, and ca-
pable of entering the roots of plants. It also acts upon the
silicates and aids to form nitrates, especially nitre, (nitrate
of potassa,) a salt which, as we shall show further along, ex-
erts a powerful influence in vegetation.

IV. Nitric Acid (aquafortis) is formed in the atmosphere,
by the discharge of electricity in thunder storms. The quaii-

ACIDS OF THE ATMOSPHERE. OO

tity has not been determined, but we know from experiment
that it must be considerable. A succession of electric shocks,
through common air or ammonia, is attended with the forma-
tion of nitric acid ; Liebig found this aci*d in the rain, which
fell during seventeen thunder storms, generally combined with
lime and ammonia.

Nitric acid, as we have seen, p. 48, is composed of fourteen
parts of nitrogen, and forty parts of oxygen. It is, therefore,
capable of yielding to plants one or both of these organic con-
stituents. Whether it can be absorbed by the leaves, and de-
composed like ammonia and carbonic acid, is not yet fully set-
tled ; the fact that it readily dissolves in water, renders it proba-
ble, that its influence is confined, mostly, to the liquid state ;
and that, although there must be a small quantity thrown up-
on the leaves of plants in dew and rain, and consequently ab-
sorbed, yet it mostly enters the roots of plants, in the form of
some of its salts, and is decomposed either in the stem, or in
the leaves by the agency of light. (See chapter 3.)

V. Light carbureted Hydrogen is found also in the atmos-
phere in very small quantities. It is given off in the fermen-
tation of compost heaps, and of other vegetable matter. It is
found in marshes, and rises up from the bottom of ponds ; coal
mines also furnish it. It is a colorless, tasteless and inodorous
gas, highly inflammable and explosive when mixed with air or
oxygen gas, and is fatal to life. This gas is sparingly soluble
in water, and must enter the organs of plants. It is composed
of one equivalent of carbon and two of hydrogen, and may be
represented by CH^. Its agency in vegetation is not well
knowTi. It may yield carbon or hydrogen or both to plants.

VI. Injiuenceof the Carbonic Acid of the Atmosphere. Car-,
bonic acid is a constant ingredient of the atmosphere, but in
very variable proportions ; generally, less than one tenth per
cent, or one thousandth part by weight, and, as the acid is
more than twice as heavy as air, a very much less quantity by
volume. According to Saussure only 0,000415 of the vol-

84 BIOLOGY OF PLANTS.

lime of the atmosphere is carbonic acid. The quantity varies
according to the season, but the yearly average remains the
same.

The existence oY this acid in the atmosphere is easily ac-
counted for, by the changes which are taking place on the
surface of the earth.

1. Large quantities of carbonic acid are locked up in the
rocks, especially in combination with lime, forming carbonate
of lime, from which it is constantly liberated by chemical
changes. By this means, also, many springs constantly emit
it, and often large tracts of land throw it off from all parts of
their surface.

2. In the process of combustion this acid is always formed,
and the quantity which is thus emitted into the atmosphere,
from all the fires in the world, is very great.

3. The respiration of animals produces it in such quan-
tities, that the respiration of men alone would convert all the
oxygen of the atmosphere into carbonic acid, in 303,000 years.
But the quantity formed by other animals is probably greater
than that formed by the human species.

4. The decay of vegetables is attended by the absorption
of oxygen, decomposition of water, and emission of carbonic
acid. This must add greatly to the whole amount.

The quantity of carbonic acid thrown into the atmosphere
cannot be determined with perfect accuracy, although we
know how much there is in the air at any one time. Bischof
has estimated the quantity, evolved from springs and fissures
in the ancient volcanic district of Eifel, to be 100,000 tons or
about 27,000 tons of carbon annually. Were the same quantity
to be sent up from 500 such spots, (fourteen millions of
tons,) it would only be equal to that contained in the coal,
which is yearly consumed in Great Britain. As all these
causes are constantly operating we should suppose that the at-
mosphere would become deteriorated in a short time, and that
the relative proportions of oxygen and carbonic acid would be

CARBONIC ACID OF THE ATMOSPHERE. 85

changed ; the latter increasing at the expense of the former.
But when we examine the atmosphere, we find that there is a
fixed relation between these two substances; one hundred
parts of air contain twenty parts of oxygen by volume in one
hundred, and from five to six y^^^ part of carbonic acid by vol-
ume or about yw<j^ P^^'t by weight. So that the air, at the
present day, is just as pure, as that which existed 4000 years
ago, and, although billions of cubic feet of carbonic acid are
thrown off into the air, and an equal volume of oxygen con-
sumed, (one man consuming 45,000 cubic inches per day,)
still, this relation is not disturbed.

How is this acid disposed of? and from what source is the
oxygen derived to fill its place ? for a cubic foot of oxygen
gas, by uniting with carbon, so as to form carbonic acid, does
not change its volume. The billions of cubic feet of oxygen
extracted from the atmosphere, are replaced by the same num-
ber of billions of cubic feet of carbonic acid which immediate-
ly supply its place. There must be some cause, or causes,
which exists, capable, both of removing the carbonic acid,
and of replacing an equal volume of oxygen, which is removed
from the air, by the processes above described. This cause
is to be found, principally, in the process of vegetation.

1. The carbonic acid of the atmosphere is absorbed and de-
composed by vegetables ; its carbon assimilated, and its oxy-
gen given back to the atmosphere.

All the green parts of plants are capable of absorbing this
gas, but the property is mostly confined to the leaves, which
possess it, quite independent of the plant itself, as they per-
form the function of absorbing carbonic acid, and emitting
oxygen when separated from the stalk. The upper surfaces
of leaves appear to have peculiar organs of absorption, as they
will not perform this function when bruised. The presence
of light is necessary, in order that the leaves may decompose
carbonic acid. This fact was first proved by Ingenhouse,
who also found, that plants emit no oxygen gas, when made

86 BIOLOGY OF PLANTS.

to vegetate in the dark. In the light the leaves decompose
the acid, assimilate the carbon and a part of the oxygen, while
the remainder is yielded to the atmosphere. In the dark,
the reverse takes place ; the leaves absorb oxygen, and the
carbonic acid is not decomposed, but is thrown out into the
air ; hence, as little carbon is assimilated, plants which grow
in the shade, or in a cellar, are soft, spongy, pale and sickly.*
The quantity of acid, absorbed during the day, and decom-
posed, is greater than that given out during the night, and
the quantity of oxygen emitted by day exceeds that absorbed
at night ; hence, the atmosphere furnishes carbonic acid to
plants, and they in turn furnish oxygen to the air. Carbonic
acid thus performs a similar office to vegetables which oxy-
gen does to animals, the former purifies the juices of the veg-
etable, the latter the blood of the animal ; hence, the animal
and vegetable kingdoms contribute to each other's support.
Animals absorb oxygen, and convert it into carbonic acid ;
vegetables absorb the acid thus formed, and give back to the
air an equal volume of oxygen, necessary to support animals.
Thus the equilibrium of the atmosphere is maintained, and
both kingdoms flourish together.

Although an equal volume of gas, is given back to the at-
mosphere, when carbonic acid is decomposed by the leaves
under the influence of solar light, it is not all oxygen, but a
part of it is nitrogen. Saussure found that of 2.1 .75 cubic inch-
es of carbonic acid absorbed, only 14.72 inches of oxygen was
given back, together with seven inches of nitrogen ; part of
the oxygen is thus assimilated to the plant.

2. The quantity of carbonic acid, thus absorbed, has been
determined with some degree of certainty. In Saussiire's ex-
periments, plants absorb daily, more than their bulk, and, as
this acid is composed of 6.12 parts by weight of carbon, and
16 of oxygen in 22.12, it is possible to calculate the probable
amount of carbon, which is derived from this source. The

* See Chaptal, p. 81.

CARBONIC ACID OF THE ATMOSPHERE. 87

quantity is so great that a distinguished chemist (Liebig) has
advocated the opinion, that plants derive their carbon wholly
from the carbonic acid of the atmosphere.*

The quantity of acid thus absorbed and decomposed varies
greatly in different plants, even when placed under the same
circumstances. Saussure has proved that the portion depends
upon the surface ; hence, those plants, which have thin leaves,
absorb more than the Jleshif-leaved plants. The same is true,
as we have seen, with regard to their power of absorbing oxy-
gen gas.

Plants require different quantities of carbonic acid at dif-
ferent periods of their growth. The young plant requires but
little, because its leaves are not sufficiently vigorous to absorb,
and decompose it. The quantity required increases with the
size of the leaves ; hence, the greatest quantity is required
when the leaves have obtained a mature growth, which peri-
od is near the middle of summer in most plants, and it is at
this period that the greatest quantity is furnished by the fer-
mentation of manures, and vegetable substances in the soil.

Carbonic acid has been considered prejudicial to the ri"
pening of grain, because its presence, in large quantities,
stimulates the leaves, and increases their bulk at the expense
of the grain.

As plants during the summer season absorb the carbonic
acid of the atmosphere, it would seem that during the winter
season a much larger quantity would be found in the air, than
in the summer ; particularly as larger quantities are produ-
ced by combustion, and smaller quantities brought to the earth
by rain. This would be the case were it not for the fact that
in the tropics there is always a vigorous vegetation ; the air
is constantly circulating from the tropics towards the poles,
and the reverse. By this constant motion the equilibrium
is maintained, and there actually is a larger quantity of acid
in the air in the summer than in the winter, because the

* See third chapter.

88 BIOLOGY OF PLANTS.

causes of its production are more abundant, and some of
them more active.

There are other causes which tend to abstract the carbon-
ic acid from the atmosphere.

1. As we approach the centre of lakes or sail out upon the
sea, ihe carbonic acid of the air gradually diminishes. This
we know is due to the fact that the water absorbs it in large
quantities, but as it is capable of absorbing, under the ordina-
ry pressure, only a quantity equal to its own bulk, we should
suppose that it would soon become saturated ; this, however,
is not the case, and the water does not, so far as is known,
return it again to the atmosphere, but disposes of it in some
other way.

2. The water of rivers is constantly carrying down sub-
stances which have derived carbonic acid from the atmos-
phere, and it thus becomes fixed in the bottoms of lakes and
seas.

3. In temperate climates, vegetable matter accumulates in
the form of peat which permanently fixes large quantities of
this acid.

The presence of carbonic acid is absolutely essential to veg-
etation. This fact has been shown by Saussure, who found
that when lime was put into a glass vessel containing plants,
so that the carbonic acid, both of the air and of the soil, was
absorbed, they no longer continued to grow, and the leaves
in a few days fell off. On examining the air, it was found
to be deprived of carbonic acid ; if, however, the plant is
placed in the shade, the presence of lime to absorb the car-
bonic acid promotes vegetation ; that is, plants grow better
without the acid in the shade than with it. This process,
however, cannot be continued long, as the presence of light
and acid are required to continue vigorous growth.

By adding a small quantity of carbonic acid to that which
already exists in the atmosphere, vegetation is promoted.
When the atmosphere contains ^L- part of carbonic acid.

PRESSURE OF THE ATMOSPHERE. 89

plants vegetate much better in the sun than when placed in
common air, but a larger quantity proves injurious, and when
an atmosphere contains three fourths of its volume of that gas,
plants will not vegetate at all, any more than they will in the
pure acid. Any addition of the gas in the shade, retards ra-
ther than promotes vegetation. Sennebier has shown, that
the green color of plants depends upon the absorption of car-
bonic acid ; for this purpose light and oxygen gas must also
be present.

It is a fact worthy of notice, in this connection, that carbon^
ic acid, which is so essential to vegetation, and so grateful to
be used in solution, as a drink, acts, nevertheless,, as a slow
poison when taken, much diluted with air, into the lungs of an-
imals, and produces almost instant death, when introduced
in a pure state.

As it is produced by ordinary combustion, every year adds
many melancholy examples of its fatal power, in the case of
those who are so imprudent, as to use live coals to warm
sleeping apartments, which are not properly ventilated, or who
use furnaces for ironing, and for culinary purposes. The acid,
being heavier than the air, fills the apartment like water, and
as soon as the individual dips his head into it, he is suffocated
almost as soon as if plunged into water.
VII. 3Iechanical agency of the atmosphere.
1. The pressure of the air is of the highest importance to
the vegetable kingdom. As the pressure is about lolbs. upon
every square inch of surface, its force upon the leaves and
other parts of plants must be very great. It brings the oxy-
gen, carbonic acid and ammonia into direct contact with the
various organs of absorption. It also furnishes support to the
external surface of plants, and enables them to withstand the
pressure of the fluids within ; for were the atmosphere very
rare, or wholly removed, the processes within the plant would
injure or burst the vessels, and decay and death would ensue.
As we ascend above the level of the ocean this pressure
8

90 BIOLOGY OF PLANTS.

diminishes ; hence, plants which grow on high mountains,
receive less of the support above mentioned. It may be due
to this circumstance, that plants w\\\\ fleshy leaves flourish best
in such regions.

2. The atmosphere not only furnishes food and support to
vegetables, but it is the medium of communicating nourish-
ment, and for the action of other agents. It is by the agen-
cy of the atmosphere that water is borne up from the ocean,
and distributed to every part of the land, in the form of rain
and dew, — that carbonic acid, ammonia, odoriferous and sa-
line particles are conveyed to the organs of plants. Its per-
fect elasticity, yielding to the slightest pressure, and its con-
stant motion, give to plants their proper exercise, without the
slightest injury. It is the medium for the agency of light,
heat and electrical changes, which are intimately connected
with the vital functions of plants. Bearing, as it does, the
clouds on its bosom, it furnishes an opportunity for some of
the most sublime and beautiful phenomena of the natural
world.

The influence of the moisture of the atmosphere will be
considered in the next section.

Such are the elements of our atmosphere, and their import-
ant influence upon the vegetable kingdom. Its constitution
and properties render it beautifully and wisely fitted for its
indispensible agency. The manner in which its elements are
combined, exhibits, in a striking light, the wisdom and be-
nevolence of the Creator. The oxygen, nitrogen, and other
gaseous bodies, of which the atmosphere is composed, seem
not to be governed, as they are in other combinations, strict-
ly by the laws of chemical affinity, or of mechanical mixture.
Its constitution appears to be an exception to general laws,
for the special benefit of the animal and vegetable kingdoms.
Its elements obey nearly the laws of combination, which they
observe when they combine in other proportions ; and yet,
they are so loosely united to each other, that each seems to

BENEVOLENCE OF GOD. 91

be diffused through the other, forming independent atmos-
pheres hke a wheel within a wheel. So that any element,
which the wants of the animal or the plant may require, is
easily and readily abstracted.

But what should most excite our astonishment, as well as
our gratitude, is the fact, that out of the six distinct and dif-
ferent compounds, which may be formed from the union of
oxygen and nitrogen, and these two bodies compose almost
the entire volume of the atmosphere, only one is fitted to the
wants of the animal and vegetable economy. Five parts of
nitrogen and one of oxygen, by weight, form the atmosphere ;
fourteen of nitrogen and eight of oxygen form the exhilarat-
ing gas, a most powerful stimulant ; fourteen of nitrogen and
sixteen of oxygen form a substance, the breathing of which
causes almost instant death : fourteen of nitrogen and twen-
ty-four of oxygen form a poisonous liquid ; thirty-two of oxy-
gen and fourteen of nitrogen form one of the most poisonous
gases known ; forty parts of oxygen and fourteen of nitrogen
form the well known substance, nitric acid (aquafortis).
One of these compounds, and that too the most injurious,
nitrous acid, is formed in the atmosphere during thunder
storms. If the atmosphere were suddenly changed into this
acid, the whole face of nature would be almost instantly
clothed with the pall of death. Why do not the elements of
the atmosphere change their proportions, and produce this re-
sult? Why, but for the constant, unceasing, all-pervading
agency of a wise and benevolent Intelligence.

The composition and properties of our atmosphere adapt
it to a great variety of other purposes, aside from its influence
upon the vegetable kingdom. Its density and elasticity are
exactly fitted to the delicate structure of our lungs. Increase
its density to that of water, and we should need lungs of ada-
mant ; diminish it to that of hydrogen, and our life's blood
would rush out at every pore. This beautiful adaptation of
our atmosphere to the animal and vegetable kingdoms, not

92

BIOLOGY OF PLANTS.

only exhibits the skill and benevolence of Him who estab-
lished and upholds the laws by which it is governed ; but
challenges the constant gratitude of those, who can offer no
other return for having been placed under a constitution so
wisely ordered for their good.

Sect. 2. Agency of Water upon tlie Vital Functions of Plants.

Water is a compound body, and may easily be decomposed
by galvanism, or by adding to it sulphuric acid and iron turn-
ings. By these processes it is shown to be composed of eight
parts, by weight, of oxygen to one of hydrogen, or of one
volume of the former to two of the latter ; its constituents,
therefore, hydrogen and oxygen, enter into the composition
of vegetables in large quantities.

Water is found under three different forms, solid, liquid
and gaseous.

I. In the solid form, as in ice and snow, water exerts con-
siderable agency upon the living functions of plants. This
it does, either by its influence upon the soil, or upon the seeds
and roots of plants.

1. When water freezes in the soil, it tends to expand it,
and to break down its coarser parts ; when the surface thaws
in the spring, the top melts first, and there is produced small
apj^ertures through which the mellowing and ameliorating in-
fluence of the atmosphere is exerted. Heavy clay lands are
thus often highly benefited.

*2. Snow is supposed to be beneficial to winter wheat and
other crops. This it does by protecting the crop and the
soil from the influence of severe cold. It forms a light, po-
rous covering, which is an excellent non-conductor of heat,
and hence prevents the warmth of the earth from escapftig. On
the same principle, by covering the young shoots of plants, it
defends them from the influence of sudden varieties of tem-
perature. When the rays of the sun fall suddenly upon a

AGENCY OF WATER. 93

frozen shoot, it droops and turns black ; but if it be thawed
gradually, it will not be injured. This is supposed to be due
to the fact, that as the fluids in the vegetable organs freeze,
they expand, but the air contained in adjacent vessels suf-
fers a corresponding contraction, so that the organs are rare-
ly burst by frost. When sudden heat is applied to the plant,
in this state, the air expands more rapidly than the ice con-
tracts, arid the vessels are burst ; but when the plant is thawed
more slowly no such effect is produced. Hence the reason
for putting frozen vegetables into water, where they will thaw
gradually, in order to preserve them. Potatoes may thus be
preserved frozen during the winter, and by thawing them
slowly and drying rapidly they are not injured. Liebig has
shown that snow contains ammonia, and this fact will serve
to explain its influence upon winter wheat. It also absorbs
oxygen and nitrogen, in proportions quite different from those
in the atmosphere. The oxygen is only about seventeen in-
stead of twenty-one per cent. Dana has shown that an acre
receives annually fifty pounds of geine and salts in the snow.

II. The agency of water, in the liquid form, may be con-
veniently studied under the following heads. 1. Its solvent
properties ; 2. Its chemical agency ; 3. Its mechanical agen-
cy ; and, 4. As affording food.

1. Solvent properties of water. Water has the power of
dissolving, and holding in solution a great variety of sub-
stances, animal, vegetable and mineral. It is the great sol-
vent in all the operations of nature.

(1) When water passes through the soil, it dissolves out
its soluble salts, such as common salt, potash, lime, nitre, etc.,
and conveys these substances to the roots, and thence into
the organs of vegetables.

(2) Water dissolves out the soluble parts of vegetable mould
and of compost manures, as fast as the chemical changes in
the soil render them soluble, and fitted for the nourishment of

8*

94

BIOLOGY OF PLANTS.

plants. It thus presents these matters in a form capable of
entering the organs of absorption.

(3) In a similar manner, also, by passing over animal mat-
ters, such as horns, bones, wool and animal manures, water
dissolves those parts which are fitted for nutriment, as fast as
formed, and, in a similar way, facilitates their introduction
into the vegetable organs.

(4) Water also absorbs various gaseous compounds, such
as common air, carbonic acid and ammonia ; prevents them
from escaping beyond the reach of the plant, and conveys
them into the appropriate vessels. The quantity of carbonic
acid which water is capable of absorbing is equal, at the com-
mon temperature and pressure, to its own volume.

The quantity of ammonia is much larger, amounting, ac-
cording to Thompson, in some cases, to seven hundred and
eighty times its bulk. These substances are brought to the
earth by every shower of rain, or are absorbed as soon as
formed, in the soil. The agency of water in this respect is
of the highest importance in the nourishment of plants, because
most of the manures which are added to soils, throw off in the
process of decay, large quantities of these gases, which would
be mostly lost for the purposes of nutrition, were they not in-
stantly absorbed by the water, and retained for the use of the
plant. The air which the water holds in solution, is much less,
and, as we have seen, is needed in the process of germination,
in a free state. Generally, aJl bodies which in any way con-
stitute the food of plants, must first be dissolved in water be-
fore they can be introduced into the roots, and become a part
of the living system.

2. Chemical agency of ivattr. In the process of decay,
putrefaction, fermentation, etc. by which food is prepared for
the nourishment of plants, water is always decomposed, its
hydrogen combining with the oxygen of the air, and its oxy-
gen with the carbon of the decaying vegetable, forming car-
bonic acid, and other compounds, which are found in the hu-

AGENCY OP WATER. 96

mus, oi" vegetable mould of soils. It is also decomposed by
the mineral constituents of the soil, and by the putrefaction
of animal matters ; hence we may explain the fact, that soils,
by being left to rest for a few years, have their fertility re-
stored. This is principally due to the oxygen of the water
and of the air. This agency of water in the decay of vegeta-
ble matter in the soil, is somewhat remarkable, as its hydro-
gen combines directly with the oxygen of the air, which, with
the hydrogen of the vegetable, return more water to the soil
than is abstracted. In the process of germination, water, as
we have seen, is decomposed, and yields its oxygen to the car-
bon of the germ.

3. Mechanical agency of icater. (1) The first effect of
water, in this respect, is to penetrate the outer covering of the
seed, and to divide the soil so as to permit the roots of plants
to extend themselves freely in every direction.

(2) The second is to convey to the roots the matter which
it holds in solution. In this latter respect it is equally useful
with the atmosphere itself In passing over rocks it wears off
their particles, which, with portions of the soil, and other mat-
ters, remain mechanically suspended in it. This matter is
spread over the valleys by the overflowing of streams. Wa-
ter is thus constantly at work in wearing down the mountains
and bringing down their valuable contents upon the plains, or
forming new land by the sides, or at the mouths of rivers. In
this way, it becomes the greatest fertilizer known.

(3) When however it flows through soils charged with some
metallic salt, like the sulphate of iron {copperas), it proves in-
jurious to vegetation, and lime, or some alkali, must be added
to decompose the salt, and destroy its corrosive or poisonous
properties.

4. Agency of water as nutriment. In addition to the agen-
cy of water above described, it is used by plants as food. We
know that it constitutes a large portion of the juices of plants,
and, although a large portion of that which enters the roots is

96 BIOLOGY OF PLANTS.

transpired by the leaves, it is not all thus disposed of; the hy-
drogen, which is found in such abundance in vegetables, can
be obtained from no other source. The vital power is able
to decompose the water, and assimilate its hydrogen, while
its oxygen is either combined with some other body, and re-
jected as excretory matter ; or assimilated also to the vegeta-
ble structure. Many vegetable bodies, as woody fibre, con-
tain carbon and the elements of water, hydrogen and oxygen,
in the same relative proportions as in water, and hence water
may be directly assimilated.

III. Water in the state of vapor ministers to the life and
growth of plants, in a manner but little less effectual than in
the liquid form. It boils and is converted into steam at 212°
F., but the quantity of vapor thus produced is very small, com-
pared with that which rises at all temperatures* by a process
called evaporation, a process which is promoted by a high
temperature, extent of surface, and the dryness and motion of
the atmosphere.

1. By the constant evaporation of water from the surface
of the ocean and the land, from the leaves of vegetables and
the bodies of animals, large quantities of vapor are thrown off
into the atmosphere. This quantity is found to vary with the
temperature. At 50° F. the atmosphere contains about j\j
or yL part of its weight. At 100° F. about ■j\ or j\y part of
its weight. When the temperature is diminished, it is con-
densed and appears in the form of vapor, or is deposited in
the state of dew ; hence the diminution of temperature, dur-
ing the night, precipitates a quantity of moisture upon veg-
etables, and restores their freshness and vigor.

2. The leaves and 7'oots have the power of absorbing the
water thus thrown upon them, and, according to Liebig, af-
ter their organs of nutrition are fully matured, derive nearly

* Major Sabine states that in the intense cold of the polar seas, not
only living bodies, but the very snoto smokes, and fills the air with
vapor.

AGENCY OF DEW. 97

or quite enough from this source for the purposes of assimi-
lation. The dew conveys also carbonic acid and ammonia,
which we have seen are indispensable to vegetation.

3. But aside from the direct agency of water as an aliment,
which we have already considered, the atmosphere performs
an important agency in yielding it, at the time when its pres-
ence is most needed to modify the effects which are produced
by the heat of the sun. This influence is always beneficial,
but almost indispensable in dry seasons. The moisture which
the air contains is conveyed, during the night, to all parts of
plants, not excepting their roots, if the soil is in a proper con-
dition to admit a circulation of air. In some countries, as
Egypt, there is no rain for several months ; this defect is, in
part, made up by the heavy dews which fall during the night,
and tend to restore the languishing energies of the vegetable
kingdom. It is owing to the direct agency of the dew upon
the roots of plants, that the earth should be stirred about
them, so as to keep it light, and always permeable to the air.

4. The agency of water in the form of dew presents the
most striking illustration of its utility, and of its wise and
beautiful adaptation to the vegetable kingdom. All bodies
radiate heat into space during the night. The surface of the
earth gives off more heat than it receives, and the dew is de-
posited. But it should be remarked, that some bodies cool
much more rapidly than others ; hence these bodies will first
attract the particles of falling dew. Thus the grass plot is
wet, while the gravel walk is dry. The dew thus seems to
select the object which it would cherish, and, after having
ministered to the wants of every living plant, spends its su-
perfluity only on the naked earth or barren waste.

5. The water thus distilled into the air, is precipitated, not
only in glistening dew drops, but in refreshing showers of
rain. This arrangement is exceedingly beautiful, if we con-
sider the fact, that were all the vapor condensed at once, it
would not cover the earth more than five inches in depth ;

yy BIOLOGY OF PLANTS.

but that the quantity which mimially falls is, upon an average,
thirty-three inches in depth. Hence the water, which so con-
stantly ministers to vegetation, must be distilled five or six
times during every year,

6. The process of evaporation of water produces cold, hence
we may explain the reason that wet soils and clayey lands are
called cold soils. The water which is everywhere, and constant-
ly passing into the state of vapor, absorbs large quantities of
heat, so as to produce a difference of temperature in the air
of two adjacent fields. The only remedy is thorough drain-
ing.

Such is the indispensable agency of water in the vegetable
economy. It is the vital fluid of plants. Upon its proper
regulation depends the quantity, quality and perfection of
most of the products of the earth, especially of those intend-
ed for the use of man.

Its constitution and properties, its abundance and univer-
sality, illustrate the beneficent provisions of the Creator for
the preservation and sustenance of animal and vegetable life;
so that here, as in all his other operations, and throughout all
his works, has he shown the same skill and goodness. In
the midst of this unbounded profusion, nothing is wasted,
nothing is supplied without a purpose. Dead matter and
material agencies are all made subservient to the demands
oflife.

Sect. 3. Influence of the Imponderable Agents upon the vital
Fhinctions of Plants.

These agents are gravity, cohesion, affinity, caloric, light
and electricity. They are the great natural forces or causes
of change in the materiiU world. I shall consider them here,
only in their relations to vegetation, or in their influence up-
on the vital power.

I. Gravity. Gravity or the attraction of gravitation is that

^ INFLUENCE OF GRAVITY. 99

power which all bodies, in masses, possess of attracting each
other. Gravity causes a stone and all heavy bodies throuTi
into the air to fall to the earth. The direction of this force
is towards the centre of the body ; hence, all bodies falling to
the earth, if not arrested at its surface, would pass on direct-
ly to its centre. This force is the cause of the pressure of
the atmosphere, and of water, as well as of their motion. Wa-
ter, by the force of gravity, falls from the clouds, penetrates
the earth, and hurries to the ocean in streams and rivers.

The principal effect of gravity upon the functions of vege-
tables, is the influence it exerts upon the direction of their
roots and branches. This influence was proved by the ex-
periments of Mr. Knight, who fixed some seeds of the garden
bean on the circumference of two wheels, the one made to
revolve rapidly in a horizontal direction, and the other in a
vertical direction. The beans were supplied with the requi-
site conditions for germination, and although the revolutions
on the vertical wheel were two hundred and fifty per minute,
and those on the horizontal, one hundred and fifty, the beans
all grew. The roots in the vertical wheel pointed in the di-
rection of the radii, and the stalks towards the centre where
they soon met. In the horizontal wheel the centrifugal force
conflicted with that of gravitation, and caused the stems or
stalks to meet, in the form of a cone, over the centre of revo-
lution, while the roots took an opposite direction. There
can be no doubt, that gravity exerts considerable influence on
the direction of the roots and stems of plants, and yet the rea-
son why the seed takes root downward, and bears fruit up-
ward, must be attributed to the laws of vitality *

II. Cohesion. Cohesive attraction holds the parts of bo-
dies together. This is shown when two leaden bars are
scraped smooth, and pressed together ; they will adhere with
a force proportioned to the closeness of their contact. If that
is perfect, the bar will yield in any other part as easily as at

* See Davy's Ag. Chemistry.

100 BIOLOGY OF PLANTS.

the point of junction. Cohesion gives to fluids a globular
form as in the case of drops of water. A modification of this
power, called capillary attraction, has considerable influence
in the ascent of the sap through the common vessels, and in
the absorption of moisture by the leaves and roots of plants.
The mode, in which this is done, may be shown by placing
straws in a basin of water ; the water in the straws will rise
much higher than that in the basin. The principle is exem-
plified in the wick of a lamp, the oil being drawn up by this
power ; also in the sponge, in sugar, and almost any body con-
taining small tubes or pores. The force of cohesion, however,
does not fully account for the ascent of the sap, although it
may aid other forces in promoting its circulation.

III. Chemical Affinity. This power differs from gravita-
tion and cohesion in the circumstance, that its force is always
exerted between different kinds of matter.* A bar of iron,
for example, is held together by cohesion, and is attracted to
the earth by gravitation; but when the iron is moistened, the
oxygen of the water, a very different substance from iron,
unites with it and forms iron rust. This is effected by chem-
ical affinity. So in the common soda powders, the tartaric
acid and the soda, two different kinds of substances, combine
by the force of chemical affinity. Various kinds of matter
possess this attraction with different degrees of force ; thus,
in the soda powders, the soda is combined by affinity to car-
bonic acid, but the tartaric acid has a stronger attraction for
the soda than the carbonic acid has, and displaces it; the
liberated gas passes up through the water, and gives rise to
the foam and eflfervescence which is so desirable and grate-
ful, when such waters are used as a drink. This is some-
times called elective affinity, and gives rise to all the decom-
positions of matter. It will be readily perceived, that this
agent must exert great influence in the phenomena of vege-
tation. The soil itself is composed of substances united by

* See Introduction.

AGENCY OF AFFINITY. 101

chemical affinity. All the decompositions and recomposi-
tions, which take place in its mineral ingredients, and in the
vegetable and animal manures are due to this power. Hence,
it is active in dissolving the rocks, in forming saline com-
pounds, and in converting manures into vegetable food. The
nutriment, it is supposed by some, is held in solution in water
by this same force. The sap itself is prepared for the pro-
cess of assimilation, and even in this process, that is, in form-
ing the various vegetable products, affinity exerts a constant
agency, although controlled by the vital power, and made
subservient to it.

Most of the substances which are added to the soil owe
their utility to the changes which this power produces, espe-
cially the application of saline manures, such as lime, potash,
ashes, etc. by which woody fibre is decomposed, metallic
salts and acids neutralized, and their injurious properties de-
stroyed and converted into nutriment.

So many are the changes in the process of vegetation which
are purely chemical, or due to affinity, that some chemists
have attempted to solve the mystery of life itself by this force,
and hence have discarded the idea of any other vital power.
It doubtless ranks next in importance to the vital principle it-
self, and is employed by it in nearly all the organic changes,
through which the plant passes from the seed to mature growth.

IV. Caloric. The influence of heat in vegetation is well
known, but the precise manner in which it accomplishes its
beneficial or injurious effects, may need some further illus-
tration.

Heat or caloric exists in two states, sensible, or the heat of
temperature, and insensible, or in a state incapable of affect-
ing the senses. The tendency of caloric to pass from one of
these states to the other, as the forms of matter change, is
one of the most important properties to consider, in its rela-
tions to vegetation. A second property is its tendency to ex-

9

102 BIOLOGY OF PLANTS.

pand all bodies, gaseous, liquid and solid ; and a third is, its in-
fluence on affinity.

1. Its influence on affinity is due to its solvent and volati-
lizing properties. By its accumulation in bodies, it destroys
cohesion and dissolves or melts them, and brings their parti-
cles into contact, so as to produce chemical combinations ; or
else it volatilizes the bodies, and removes the particles from the
influence of each other's attractions. In these ways it aids or
retards the decompositions and recompositions in the soil, and
becomes a powerful agent in preparing the proper food of
plants.

2. The effect of heat in the spring and summer is to ex-
pand the tubes or vessels of vegetables, in which the sap cir-
culates, and also, if not too great, to render the juices more
fluid. It thus promotes a more easy introduction of sub-
stances into the roots, and a more rapid circulation through
the stems, branches and leaves.

But if the heat is too great, which often happens during
dry seasons, when neither rain nor dew is sufficient to coun-
teract its effects, the juices become thickened, and the vessels
contracted ; the plant shrivels up, and often wilts and dies.
This effect would be produced more frequently, were it not,

3. For the tendency of heat to pass into an insensible state
in the process of evaporation of water from the soil, and from
the plant itself, and were not the plant otherwise protected,
from extremes of temperature.

The fluids, which pass into the plant, are some of them
converted into solids by assimilation. This process increases
the temperature of the plant, by rendering hisc7isihlc caloric
sensible, and is a means of heat, when sufficient quantities
from without are not supplied. But the greater part of the
water, which enters the root, is thrown out or transpired by
the leaves, and other green parts. The moisture thus thrown
out upon the outer surface, by passing into vapor, absorbs the
sensible and external heat. The higher the temperature, the

INFLUENCE OF CALORIC. 103

more rapidly will the water evaporate ; thus the influence of
external temperature is modified, and the vital powers pre-
served.

The quantity* of water thus transpired amounts, in some
cases, to the weight of the plant in twenty-four hours.

The outer or upper surface of the leaf is further protected,
both from the too excessive heat of the sun's rays and from
the agency of water, by a thin lining of silica (flint), which
reflects the rays. This is particularly the case with herba-
ceous plants or grasses ; the epidermis or outer coat of the
stalks and leaves being composed in part of this substance.

The temperature of the atmosphere is kept cool in the
spring, by the heat which is required to convert the snow and
ice into water, and the water into vapor. The process of
evaporation moderates the temperature during the summer
months, and the condensation of vapor in the autumn gives
out heat to the air, while its conversion into ice and snow
still further moderates the approach of winter.

In this way, the vegetable kingdom is preserved from the
extremes of heat and cold, and from those sudden transitions
which might otherwise injure or destroy it. See page 35.

4. During the winter, the roots of vegetables, of grasses
and trees are preserved from excessive cold, by the non-con-
ducting properties of snow and ice. The surface being fro-
zen, the heat of the earth is retained, and the principle of vi-
tality guarded from injury. The conversion of the juices of
the plant into ice does not take place until a low temperature
is reached. When this happens it developes its latent caloric,
and the temperature of the tree from this source must be, up-
on'an average, above that of the surrounding atmosphere.

By the variations of temperature, winds are produced, and
the moisture precipitated to the earth in the form of dew and
rain. By these golden showers the processes of vegetation
are carried forward and enables the earth to yield her increase.

* See Dana's Muck Manual, p. 225.

104

BIOLOGY OF PLANTS.

These laws, by their wise constitution and their constancy, aid
in fulfilling the decree of heaven, that while the earth remains,
seed time and harvest, summer and winter, cold and heat,
shall not fail.

Finally. The distribution of plants over the surface of
the earth is governed more by temperature than by any other
circumstance. It is well known that each species of plants
has its natural limit. This is particularly true of the food-
bearing plants; and their agricultural limits are principally
determined by temperature and moisture. The northern
agricultural limits are bounded by lines passing through places
of equal summer heat and are called isotheral lines.

The southern agricultural limits are bounded by similar
lines of equal winter heat, and are called isochimenal lines.
These lines are exceeding tortuous in their course around
the earth. Thus barley, the grain which has been cultivated
farthest north, has its extreme limit in the Shetland Islands,
61° N. ; in the Feroe Islands, 61°— 62^^° N. ; Lapland, 70° N. ;
near the White Sea, between 67° and 80° N. ; in Eastern Rus-
sia, about 66° N. ; and in Central Siberia, between 58° and
59° N. In North America the line is probably similar. The
limit for the potato extends a little farther north. Now it
is found that this line passes through places of equal summer
temperature, the mean of which is from 46° to 47°.

Or if a similar examination of the northern limits of wheat
be made, it will be found, that equal summer temperature is
the condition of the limit. This is in latitude 64°, and the
average summer temperature 57.4° F. This limit coincides
with that of fruit-trees, apples, pears, and also of the oak. Other
grains have similar isotheral lines which limit their northern
cultivation.

If now we turn to the equatorial regions, we shall find that
the limits are governed by equal winter temperature ; for it is
found that extreme heat arrests the cultivation of the grains.
The temperature for germination must not exceed 120 de-

AGENCY OF LIGHT. 105

grees. This limit is about 20° N. latitude. The southern
limit of barley is farthest north, after which wheat, then rye,
and farthest south, Indian corn. Near the southern limit, as
in Bengal, '' Wheat, barley and oats are sown in the autumn,
and harvested in March ; while rice and maize are sown in
May, to be harvested, as with us, in October."

It is the same condition of temperature, which limits the
cultivation of the food-bearing plants on mountains. Thus,
in the Alps the grains cease growing at the following heights :

Wheat at 3,400 feet, corresponding to latitude 64 degrees.
Oats 3,500 " " 65 "

Rye 4,600 " « 67 "

Barley 4,800 " " 70 "

The above facts show the indispensable agency of heat up-
on the vital power, and should lead the farmer to adapt his
crops to its influence, as affected by the location of the farm
and the character of the soil.

V. Light. Light has been shown to consist of three
kinds of rays. 1. Colorific, or those rays which give color
to the various objects in nature. 2. Calorific, or those rays
which produce heat, and are the cause of the sun's warmth.
3. Chemical rays, or those which produce effects upon chemical
combinations. These rays are easily separated by means of
a prism. Whether the effect upon vegetation results from a
combination of all the rays, or is produced by one kind, is
not certainly known ; but the probability is that the power, in
this respect, depends partly upon the chemical rays, and part-
ly upon the colorific rays.

1. Light is a powerful stimulant to vegetation, changing
the color of the leaves and stalks, and giving the pungent pro-
perties peculiar to each species of plant. Those vegetables
which grow in the shade are always pale and sickly in growth,
and insipid in taste. But let a ray of light cross the stem or
leaf of such a plant, and it will turn green in that spot, and
become pungent, although all other parts remain as before.
9*

106 BIOLOGY OP PLANTS.

2. But the most direct agency of light is seen in the pow-
er which it gives to the leaves, to decompose the carbonic
acid, and prepare the juice for the processes of assimilation.
Plants which grow in the dark do not possess this power, and
hence the acid remains in the juices, and the carbon is but
feebly assimilated. We can see the reason why vegetation
is more flourishing in the torrid zone ; there is a greater
quantity of light there. But each plant seems to have a con-
stitution peculiar to itself in this respect ; some being able to
flourish better in the shade than others. There are some kinds
of grasses, and many flowers which will flourish best in the
shade, while others require to be exposed to all the light there
is, and if the natural quantity is not supplied, will wilt and
die.

3. The different effects produced by rays of different colors
has been pointed out by Mr. Hunt. In his experiments,
cress seeds were exposed in the soil to the action of the
red, yellow, green and blue rays, which were transmitted
through equal thicknesses of colored infusions. " After ten
days, there was, under the blue fluid, a crop of cress of as bright
a green as any which grew in full light, and far more abun-
dant. The crop was scanty under the green fluid, and of a
pale, yellow, unhealthy color. Under the yellow solution,
only two or three plants appeared, but less pale than those
under the green ; while beneath the red, a few more plants
came up than under the yellow, though they also were of an
unhealthy color. The red and blue bottles being now mu-
tually transferred, the crop formerly beneath the blue in a
few days appeared blighted, while on the patch previously ex-
posed to the red, some additional plants sprang up."

The necessity of light to the health and vigor of plants, is
a matter of daily observation. They seem, as it were, to be
endowed with a kind of instinct for it. How constantly do
many leaves follow the sun in his daily course ! What count-
.less numbers of blossoms close and drop when he retires at

AGENCY OF ELECTRICITY. 107

night, and turn their faces as if eager to catch the first rays
of the morning !

VI. Electricity. Electricity is a much more subtle
agent than any which have been named ; and although the
mode in which it produces its effects is not so easily discov-
ered, yet from some experiments it is rendered probable, that
its action is nmch more direct and efficient upon the vital
functions of plants, than has been commonly supposed. It
seems to be widely disseminated throughout the atmosphere,
the water, and the soil.

Electricity is developed by friction, and by chemical ac-
tion. The former is called common^ the latter Voltaic elec-
tricity, or Galvanism. Change of temperature and of form
develope it, the condensation of vapor, the variations of
temperature in the atmosphere, and the chemical changes,
which take place in the soil, are constant sources. The na-
ture of the electric fluid is unknown.

Theory. It is supposed to consist of two fluids pervading
all matter ; the one is called positive or vitreous ; the other,
negative or resinous. Each repels itself, and attracts the op-
posite.* Acids are generally negative, and alkalies positive;
hence, the electric state of the soil may generally be known
by its composition.

If a soil is wholly negative, as is the case with pure
silica or sand ; or wholly positive, as is the case with alumi-
na, lime, magnesia, iron and the alkalies, it is always wholly
barren ; or when one ingredient greatly predominates, it is
unfavorable to vegetation ; and the object of amendments is
to bring the soil to a neutral state.f The animal and vege-
table substances in the soil produce acids and alkalies, which
develope by their affinities electrical currents. The soil, be-
ing composed of different minerals, and saturated with mois-
ture,constitutes a galvanic battery, which is constantly acting
upon the functions of vegetables, and upon the rocks.

* See Gray's Chemistry, p. 74. t See ' Soils,' chap. 5th.

108

BIOLOGY OF PLANTS.

That the electrical powers thus developed must exert a
constant and powerful agency upon the growth of plants, ap-
pears from the fact, that electricity is a most efficient pro-
moter of endosmosc or absorption. Endosmose is a term,
which Mons. Dutrochet has given to a peculiar power which
he discovered in experimenting upon the permeability of tis-
sues. Its name is from the Greek, and signifies intei-nal im-
pulse. It seems to be a property possessed by all thin, mem-
branous substances, when liquids of different densities, and
electro-motive powers are placed on each side of the mem-
brane. The following is a mechanical illustration of this cu-
rious property.

Fig. 13 represents
the endosmometer. It
consists of a small bell-
glass receiver a, with
a glass tube c, open at
both ends, and accu-
rately fitted to the ap-
erture in the top c.
Over the mouth of the
receiver is stretched
any membrane, as a
fresh bladder ; and a
metallic substance, e-
ven and firm, with aper-
tures punched through
it, is placed upon the
membrane as a support. The receiver may then be filled
with sweetened water, molasses, or almost any substance
denser than water, through the cork c. The receiver must
now be placed in a vessel of water 6, so that the water on the
outside of the receiver shall be at the same height with the
substance within. If now this is suffered to remain, the mem-
brane will draw in the water, and force it up the tube, as

AGENCY OF ELECTRICITY. 109

d. The force thus exerted by the membrane is equal to the
weight of the atmosphere, as it vvouJd, in time, raise the col-
umn of water thirty-two feet in height. If now P, the posi-
tive wire of a galvanic battery, is immersed in the water, and
n, the negative wire communicate with the interior through
the cork e, the effect will be greatly increased ; and, if the
wires are reversed, the liquid in the receiver may be made to
flow out into the vessel of water.

According to the experiments of Dutrochet, the ascensional
force in this instrument is about equal to the pressure of the
atmosphere ; and Mirbel found the ascensional power of the
sap in a grape-vine to be the same as in this instrument. By
cutting off a grape-vine, and adapting to it a glass tube filled
with mercury, the outpouring of the sap will raise the mercury
twenty-eight inches in the tube.

If now we examine the spongioles of vegetables, we shall
find, that each has a bladder which stands out to absorb the
nutritious particles ; and that the tubes are filled with mem-
branes, in which the endosmometric action is produced. The
fluids constituting the sap are generally denser than water, a
circumstance which is esssential to the action. If we sup-
pose currents of electricity, developed in the soil, to be passing
through the tubes of the vegetable, we have perhaps the most
satisfactory theory of the ascent of the sap* which can be
furnished. Hence it appears that one prominent object of
the agriculturist is to balance the electrical forces in his soil,
in order that the highest effect of this power may be produced
upon his crops. There appears also to be an opposite move-

* As the ascent of the sap may thus be accounted for on mechanical
and electrical principles, it may be thought that this example is op-
posed to the views respecting the vital principle^ which were present-
ed in the first chapter. But it should be remembered, that the effect
here depends upon the tissue or membrane which is a product of vital-
ity. How can chemical laws construct the spongelets, and the mem-
branes, which must be placed across the tubes in which the sap cir-
culates .''

110

BIOLOGY OF PLANTS.

ment in theendosmometer, but the liquid passes out, in much
less quantities than it passes in. This movement is called
exosmose, and may illustrate the process of transpiration, or
perhaps favor the theory that plants excrete nourishment into
the soil, unfitted for their own species, but capable of nourish-
ing those of a different family.

The influence of electricity upon germination, according
to Davy, is to increase the vital energies. He found that
corn sprouted more rapidly in water positively electrified by
the voltaic battery, than in water negatively electrified. We
should suppose, from analogy, that electricity would exert a
powerful influence upon the vital power of vegetables, from
its known influence upon this power in minerals. In medi-
cine, it has long since been employed as a remedy, especially
to restore sensation to parts which have become deprived of
feeling. Some experiments seem to prove, that continued
voltaic action upon animals of microscopic dimensions, so
excites and quickens the vital power, as to increase their
growth a thousand fold ; thus, converting animalculae, which
are too small to be seen, into visible and tangible insects.
This fact has led some men even to adopt the hypothesis,
that they were created by this power, that the vital and
electrical powers were identically the same, and that the pro-
cess of life is carried forward by a galvanic battery, consist-
ing principally of the brain and nervous system.

As vegetables, however, are not sensitive beings, it is
more difficult to trace in them, the influence of this agent ;
but enough is known to infer its utility, and perhaps neces-
sity to the existence of the vegetable kingdom.

Sect. 4. Agency of Man.

There is but one remaining agent required for the most
vigorous action of the vital principle, and that is the farmer
himself. The vital power may exist in the seed, but it will

AGENCY OF MAN. Ill

not develope itself without his care and skill. He cannot act
directly upon the functions of plants, as the other agents do,
but he can modify, and, to a certain extent, control the influ-
ence of those agents. He must learn the conditions required
for their beneficial action. He is the overseer, who brings
together natural powers, that they may act usefully upon
each other, and upon the materials which are to be manufac-
tured. And although his agency is secondary, still it is not
less necessary or beneficial, than if he could cause his crops
to grow by direct power ; for although the agents we have
described, act with their own efficiency, and according to
their own fixed laws, still they are under the control of the
farmer, to a much greater extent than he supposes.

In reference to the vital power itself, we have already seen
the agency of the farmer : he must supply it with certain con-
ditions, proper food, soil, tillage, etc. before he can expect a
bountiful crop. The other agents are perhaps less under
his control, and it may be asked by some, of what use a de-
scription of them can be to a practical farmer. On the sup-
position that the atmosphere, water, light, heat and electrici-
ty, do exert all the influence which is claimed for them, are
they not beyond the control of man ? How can the farmer
make the sun shine warmer or brighter, or the rains and
dews descend in greater or less quantities ? How can he
control those mysterious powers of electricity and aflSnity,
whose universal agency is witnessed by all ? These inquiries
arise from an erroneous idea of the case, from a false idea of
the processes above named. It is because these agents are
under the control of the farmer, not directly but incidentally,
that they are brought forward for his consideration. Their
agency is not a matter of mere science, but of practical utili-
ty, of vast importance to every man who attempts to cultivate
even a garden.

1. The atmosphere and its contents. How can the farmer
employ this agent 1 He can secure its agency by so prepar-

112 BIOLOGY OF PLANTS.

ing and tilling his soil that its moisture, carbonic acid, oxy-
gen and other constituents, may circulate freely through it,
to all parts of the roots. By giving to the soil a proper con-
sistency, and by supplying it with vegetable and mineral sub-
stances, the elements of the atmosphere are made to act upon
the vital functions with greater power. Thus, by giving to
the soil greater absorbing power, it will feel the influence of
the dews ; by draining it, the injurious effects of water will
be prevented, and the action of the air facilitated. If, there-
fore, the farmer cannot cause the rains and dews to descend at
his will, he can so prepare the soil that the highest advantage
may result from the influence of these agents.

2. The influence of heat. How can this agent be applied
by the farmer ? Simply by adding to the soil, mineral or vege-
table substances, which will give it the power of absorbing
and retaining the heat of the sun, or which will, by their com-
binations, produce heat in the soil. By the fermentation of ma-
nures, great quantities of heat are given out ; hence, if the
soil is naturally cold, manures should be applied before they
are fermented, and incorporated with the soil that the heat
may be equally distributed. By increasing the fertility of the
soil, its power of retaining heat will be increased.

3. Electricity. How is the influence of this agent con-
trolled by the farmer ? If a soil is acid, that is, in a state of
negative electricity, it is wholly barren ; if a soil is alkaline,
that is, in a positive state of electricity, it is also barren ; but
when its acids are neutralized by its alkalies, then it is in a
state favorable to fertility, and the more completely the elec-
tro-powers of the soil are balanced, the more fertile will the
soil become. Now, by analysis, the electrical state of the soil
can be determined, and the substance applied which will re-
store the equilibrium of the electric forces. From the analy-
sis of soils of different degrees of fertility, it is surprising to
notice how narrow the limits are, between absolute barren-
ness and a high state of fertility. One soil, for example,

AGENCY OF MAN. 113

which is wholly barren, may have its fertility restored by the
addition of one per cent, of lime, or even a few bushels to the
acre. Another, which is acid, and therefore unfavorable to
vegetation, may by the addition of a single grain in a hun-
dred of some alkali, be made to yield forty, fifty, or a hundred
fold.

Many a farm has remained for years barren, because its
electrical forces were not properly balanced, while the addi-
tion of some well-known substance, perhaps in the proportion
of not more than one grain in a million, would restore it to
fertility. It is said by certain medical practitioners, that a
millionth part of a grain of arsenic or opium, will act with
better effect upon certain diseases, than much larger quanti-
ties. This doctrine of the homoeopathist, applies with per-
fect truth to the application of certain salts to the soil. It is
often surprising to notice the effect of a single grain of lime
or potash in a hundred of the soil, doubling, tripling, and of-
ten quadrupling the quantity of the productions in a single
year. This result must be due, in part, to the electrical ef-
fect which this small addition produces ; hence we may learn
both the importance of ascertaining the composition of soils
by accurate analysis, and of improving them by adding those
substances which they require.

In conclusion, it may be remarked, that the agents, consid-
ered in this and the preceding chapter, are not only the great
causes of change and reproduction in the vegetable, but also in
the animal and mineral kingdoms. Most of them are the natu-
ral powers ordained of God for the government of the natural
world. A correct knowledge of them will help us to explain
the almost infinitely varied and mysterious phenomena which
are every day presented to our minds ; and when we have
begun to understand their agency, when we can trace the
chain of effects to the ultimate cause we shall find, that they
will present subjects of deep and delightful reflection.

They will enable us to gain a deeper and more profitable
10

114 BIOLOGY OF PLANTS.

insight into the mysteries of nature, and to be better fitted to
discharge our duties as citizens and as men ; our toils will
become lighter, because we shall find in our employment an
interest and a soul.

9

CHAPTER III.

PRODUCTIONS OF THE VITAL PRINCIPLE THEIR CHARACTER,

COMPOSITION, SOURCES AND ASSIMILATION.

Having in the preceding chapters given a general account
of the vital principle, and the agents which act upon it, in-
cluding the general processes of vegetation, we come now to
describe the productions of this power ; for, in opposition to
the views of many chemists and vegetable physiologists, we
still insist, that this power actually/ ensts in vegetables, and
that we have good reasons for ascribing to it, as a principal
agent, the various compounds which are found in vegetable
bodies. The character of these compounds is wholly differ-
ent from that produced by a chemical or a mechanical agent.
Their composition cannot be accounted for by ordinary chem-
ical changes ; and the source and assimilation of their simple
constituents, teach the same doctrine. This chapter, there-
fore, will be devoted to the discussion of these topics.

Sect. 1. Character and Composition of the Vegetable Pro-
ductions.
The productions of the vital power are very numerous.
They are called vegetable or proximate principles, such as
sugar, gum, and starch ; and differ, materially, in their char-
acter and composition, from inorganic bodies. The vegetable
principles exist in plants, already formed ; and the processes
by which they are separated, are called proximate analysis.

PRODUCTIONS OF THE VITAL PRINCIPLE. 115

These processes are various, and are described in works on
elementary chemistry. Many of them, however, are well
known to farmers, such as the obtaining of starch from pota-
toes or wheat, of sugar from the juice of the maple, beet-root,
etc. The vegetable proximate principles are all decomposed
by a red-heat, and are converted chiefly into carbonic acid
and water. When subjected to ultimate analysis, they are
found to be composed of carbon, oxygen, hydrogen and nitro-
gen. Small quantities of phosphates, sulphates, metallic ox-
ides and earths are found in vegetable bodies ; which, though
essential to them, constitute but a small portion of their sub-
stance, and are called the inorganic constituents of plants.
The vegetable, as it is formed in nature, contains alkalies
and metallic oxides, in combination with ihe proximate prin-
ciples, although the latter, as such, contain no metallic bases.

The simple bodies O. C. H. N. are found combined in va-
rious proportions. Generally a larger number of equivalents
are united to form the organic than the inorganic body.
Some organic bodies are composed of two, some of three,
and others of four simple bodies ; and the proportions vary
from one to seventy equivalents or more, but in inorganic
bodies, rarely more than seven equivalents of the same ele-
ments are found.

I. Organic principles, composed of two ingredients, are of
four kinds.

1. Compounds of carbon and hydrogen, as in oil of turpen-
tine, which is composed of C'^H^,* and in the volatile and
fixed oils.

* It will be recollected that the four bodies, carbon, oxygen, hydro-
gen and nitrogen, are represented by their initial letters, C. O. H. N.
and the number of equivalents are represented by figures placed as in-
dices ; thus C^, O^, signifies a compound formed of 2 equivalents, or 12
parts by v/eight of carbon, and 3 equivalents, or 24 parts by weight
of oxygen. The equivalent of hydrogen is 1, oxygen 8, carbon 6.12,
and nitrogen 14. We have only to look at the indices, to ascertain
the number of equivalents in any compound, and by multiplying that

116 BIOLOGY OF PLANTS.

2. Of hydrogen and oxygen, as water, which is formed of
OH.

3. Of carbon and oxygen, as oxalic acid, composed of
C203.

4. Of carbon and nitrogen, as cyanogen, composed of C^N.

II. Oi'ganic principles, composed of three constituents, are
much more numerous than the preceding.

1. The most common combinations are carbon, hydrogen
and oxygen. Sugar, gum, etc. and the greatest number of
acids, are thus constituted.

2. Compounds of carbon, hydrogen and nitrogen, as azul-
mic acid which is thus constituted, C^HN^.

3. Compounds of carbon, oxygen and nitrogen, as carba-
zotic acid, CisN^O^s.

III. Organic principles of four constituents, as aspartic
acid, C^H^NO^. Almost all the alkalies contain these four
substances.

Of the simple substances, carbon is most abundant, and
next are oxygen and hydrogen ; while nitrogen, although not
absent from any part of a plant, exists in very small quan-
tities in all.

But the substances which constitute the principal mass of
every vegetable, are compounds of oxygen and hydrogen (in
the proportions to form water) and of carbon. In a second
class, oxygen is in excess, as in the numerous organic acids.
In a third class, as the volatile and fixed oils, carbon and hy-
drogen exist, but no oxygen, and in a fourth class nitrogen
is added, as in vegetable albumen, in indifferent substances,
and in some acids.

by the number represcnlinir the equivalent for that substance, the ex-
act amount by weight may be obtained. The whole added together
gives the equivalent of the compound, which is also represented by
numbers. This mode of represention is now adopted by all chemical
writers, and seems useful to present tlie compounds to the eye in a
condensed form.

VEGETABLE ACIDS. 117

The vegetable principles are divided by Thompson into
the four following classes.

I. Acids. 11. Alkalies. III. Intermediate bodies. IV.
Neutral bodies.

The substances, classed under these heads, are not all the
products of the vital principle. Some of them result from de-
compositions, and hence are the products of death rather than
of life.* A large number of the products of vitality are in-
serted in this section as a convenient reference for those who
have not better sources of information. The agricultural
reader can omit them, if he chooses, altogether.

I. Acids. The number of acids, derived from the vegetable
kingdom, amount to 116, but a few of this number are of any
particular impoitance to agriculture. The following are the
principal vegetable acids. Oxalic, citric, tartaric, benzoic, me-
conic, acetic, malic and prussic acids. All, save the last three
which have been obtained only in a liquid state, are white crys-
taline solids. All are more or less soluble in water. All are
sour to the taste, with the exception of gallic and Prussic acids,
the first of which being astringent, and the latter having the
taste of bitter almonds.

1. Oxalic acid (€^03=36.24)1 is found in wood sorrel, [Oxalis
acetosella,) and is the cause of its sour taste. It also exudes from
the chic pea [deer arietinum). Many vegetable principles, such
as gum, starch, etc. are converted into this acid by nitric acid.
It exists in small, slender crystals, resembling epsom salts, for
which it is sometimes mistaken with fatal consequences. It is
a powerful poison with a strong acid taste. It is distinguished
by its power of decomposing all salts of lime, and forming with
the base an insoluble salt. This acid is found in combination
with lime [Oxalate of lime) in several species of lichens. When

* For a complete description of all the vegetable principles, the rea-
der is referred to Thompson's Chemistry of Organic Vegetable Bodies.

=1 The expression, 020^=36, when translated, would read thus :
Oxalic acid is composed of 2 equivalents of carbon, or 12.24 parts by
weight, and 3 equivalents of oxygen, or 24 parts by weight, which
makes an equivalent of oxalic acid equal to 36.24 ; that is, when oxalic
acid combines with any other body, it always unites 36 parts by weight.

10*

118 BIOLOGY OF PLANTS.

first precipitated, the oxalate of lime (C^OSCaOSHO =82.74) is a
snow-white, floculent powder.

Oxalate of potassa* is commonly called the tssential salt oj
lemons, and is used to remove spots and iron rust from linens.

2. Citric acid (C^H2O''=G0) is found in many acidulous fruits,
such as limes, lemons and oranges. It is distinguished by form-
ing an insoluble salt with lime, and is used in preparing
lemon syrup.

3. Tartaric acid {^^11^0^=66.24:) exists in acidulous fruits,
especially in the juices of the mulberry and grape, usually in
combination with lime or potassa. It is the substance used
with soda for an effervescing drink. Bitarirate of potassa is
foimd in old wine casks, and when purified, is called cream oJ
tartar, and is used in medicine. Tartar emetic is a compound
of tartaric acid with potassa and antimony, and is neutralized
by astringents, such as tea or Peruvian bai"k, in case too large
a dose is taken.

White Rochelle salt is formed of potassa and soda, combined
with tartaric acid.

3. Benzoic acid (C^^H503=123) exists in gum benzoin, in
the balsams of Peru, and some other vegetable substances. It
is distinguished by its volatility and aromatic odor ; although,
when perfectly pure, it has no smell. When sublimed, it forms
long, flat, prismatic nodules, having a beautiful satin lustre.

4. Meconic acid (C'^H20'''== 100,84) is found in the poppy, in
combination with morphia, and crystalizes in white, transj)arent
scales.

5. Gallic acid (C'''H305=85) is found in gall-nuts and in the
bark of trees. It forms ink by combining with the proto-sul-
phuret of iron.

6. Tannic acid (CiSH^Oi^^Qi^) exists also in gall-nuts, in
tea and vegetable astringents, and is the cause of their astrin-
gency. With gelatine or glue it forms an insoluble compound,
which is the basis of leather ; hence its use in tanning hides.
Tannic and gallic acids possess the property of preserving
bodies from decay.

7. Acetic acid (C^H303=51,48) exists in the sap of many
plants. It is well known under the name o{ vinegar. It forms
numerous salts with inorganic bases, such as acetates of lead {su-

* When an acid combines with an alkali or metallic oxide, the
substance formed is called a salt, and the name of the acid changes its
termination into ate, or if the acid terminate in ous, into ite.

VEGETABLE ALKALIES. 119

gar of lead) ; of copper (verdigris) ; and many others, which
are useful in the arts.

8. Malic acid {C''H2O4=60) is obtained from the juice of
apples, barberrieSj plums, elder-lierries, currants, strawberries,
raspberries, etc. It is distinguished from the preceding acids,
by forming soluble salts with lime.

9. Pnissic acid (C2NH=27) is obtained by the distillation
of laurel leaves, from the stones of the peach, cherry, and bit-
ter almonds. This is the most violent poison with which we
are acquainted.

The above are only a few of the vegetable acids. They impart
to fruit that tart, pleasant taste which forms their distinguishing
characteristic.

II. Alkcdies. This class includes about thirty-seven sub-
stances, all discovered since 1817. Those plants which are
remarkable for their poisonous or medicinal properties, contain
an alkaline principle. Those most important in this connec-
tion are Morphina, Narcotina, Cinchonina, Quinina, Strychni-
na, Emetina, Nicotina, Conicina, Solanina, Parillina. They are
compounds of hydrogen, oxygen, carbon and nitrogen ; and
their composition will be indicated by symbols, as in other

1. Morphina {C^'^W^'NO^=2S4l) is the narcotic principle
of opium, and constitutes about -^\ of its weight. It is a well-
known poison, of an astringent bitter taste. It is used in medi-
cine to allay pain. When opium has been administered as a
poison, a skilful chemist will detect a single grain of the mor-
phina in 700 grains of water. It is contained in the capsule of
the poppy, from which it is generally obtained. It combines
with a great many organic and inorganic acids ; and the salts,
thus formed, are used extensively in medicine.

2. J^arcotina (C^OH^ONOi^) is found in opium. It is not in-
jurious to man, but fatal to dogs !

3. Cinchonina (C20H'2NOl^=158) is found in Peruvian bark
{cinchona nitida, or condaminea), and imparts to it its value as a
medicine. It has a peculiar bitter taste, which is not perceived
at first, in consequence of its insolubility. It crystallizes in deli-
cate prismatic needles, or in white translucent tufts ; and, by
uniting with acids, forms a great number of organic salts.

4. quinina [C^^^^N 0^=162) is also foimd in connection
with Cinchonina and is used for a similar purpose. The std-
phjte of quinina is manufactured on a large scale, and sold as

Quinine. It is intensely bitter, and is of great value in certain
diseases.

120 BIOLOGY OF PLANTS.

5. Strychmna (C30H'6NO3=237.75) is found in the nux vom-
ica [strychjios mix vomica), the St. Ignatius bean {strychnos igna-
tia), and the upas. It is an intensely bitter substance, and one
of the most violent poisons yet discovered. Its action is ac^com-
panied with symptoms of locked-jaw.

6. Emetia or Emdina (C35H25NO9=308) is found in several
plants, especially in the roots of the ceph(Tlis emetica, ipecacuan-
ha, and possesses most powerful emetic properties. It gene-
rally exists in the form of a yellowish powder. Six, or at
most twelve grains, occasion violent vonjiting, followed by death.

7. JVicotina is the peculiar principle of tobacco, a most viru-
lent poison. It has not been fully analyzed, but is supposed to
contain more nitrogen than any of the other alkaloids.

8. Conia or Conicina (Ci~rP'*NO=108) is the active princi-
ple of conium inaculatum or hemlock, and is the most violent
poison known, with the exception of hydrocyanic or prussic
acid. It has the appearance of a yellowish liquid oil, with a
strong, penetrating smell, and acrid and corrosive taste. A sin-
gle drop, put into the eye of a rabbit, killed it in nine minutes.
Three drops, used in the same way, killed a strong cat in a
minute and a half It is a common opinion, that mineral bod-
ies are the most poisonous, but it is not the case, as the two
most violent poisons known, are derived from vegetables.

9. Solajiina, (C^SH^'N^OS^ M. Henry,) is found in the ber-
ries of the solanum nigrum, the solanum dulcamara, or common
Nightshade, and in potato-balls. It is found also in the potato-
root, after germination commences, and in the epidermis. It
is an acrid, narcotic poison, and care should be taken not to use
this root, after germination has commenced.

Parillina, (C^H^O^) is found in the smilax sarsaparilla, or the
common sarsaparilla of the shops, a substance used in the pre-
paration of mead, beers, etc. It diminishes the rapidity of the
circulation, and acts as a sudorific, producing perspiration, and
of course debilitates the system. In a pure state, it is a white
powder, with a sharp and bitter taste, slightly astringent and
nauseous.

Class III. Intermediate Bodies. In this class are included seve-
ral vegetable principles, which have not yet been shown to
possess, either alkaline or acid properties. The princij)al of
which, are coloring-matters, fixed and volatile oils, resins and
gum-resins.

1. The coloring-matters of vegetables, are usually diflTused
through other proximate principles. The most common veg-

COLORING MATTERS. 121

etable colors, are green, yelloWj blue and red. But all the colors
of (lyed-stuffs, are produced from blue, red, yellow and black,
though the latter does not exist in the vegetable kingdom, but
is formed by adding mineral bodies to the acid of gall-nuts or
logwood.

Btue dyes are derived from the indigo plant [indigofera), a
genus of plants of which there are sixty species. They are
found in India, Africa and America. Litmus has a blue color,
and is used as a chemical re-agent.

Red dyes are derived from the cochineal, an insect which feeds
on one species of the cactus ; from lac, archil, madder. Brazil-
wood and logwood.

Lac is a resinous substance, derived from the /cms Indica and
religiosa, and is commonly known as shell-lac. Archil, is obtain-
ed from a species of lichen {parmtlia roccdla), the best quality
of which is found in the Canary Islands.

Madder is the root of the ruhia tinctorum, a plant cultivated in
countries bordering on the Mediterranean Sea. This plant is
also used for a great variety of colors, forming by the addition
of mineral substances, madder-yellow, madder-orange and mad-
der-brown .

Brazil-wood is found in Brazil, and is obtained from several
species of the ccEsalpina (sapan, crista, etc.). The red coloring
matter of this wood, is rendered yellow by acids, and violet by
alkalies.

Logwood is the wood of the Haematoxylon Campeachianum
found in Jamaica, and the eastern shores of Campeachy. This
wood is chiefly employed by the calico printer, to give cotton
a brown or black color.

Yelloio dyes are obtained from the quercitron bark, which is
taken from [quercus nigra), a large tree growing in this country ;
from tumeric [curcuma longa), saffron [crocus sativus), and from
fustic [morus tinctoria), a large tree which grows in Brazil ;
from iveld, which is the dried leaves of reseda luteola, a Eu-
ropean plant ; from Persian berries [rhamnus infectorius) ; from
sumac [rhus coriaria), which grows spontaneously in Italy and
the south of France.

2. Fixed oils are usually obtained from seeds, as the almond,
linseed and poppy-seed. Olive-oil is extracted from the pulp
around the stone. After being boiled, these oils dry more
rapidly, and are then used in forming paints ; when mixed
with lampblack, they constitute Printer's Ink. In drying ra-
pidly, these oils absorb so much oxygen, as to take fire spon-

122 BIOLOGY OF PLANTS.

taneously, an accident which frequently occurs when cotton or
wool in large quantities is moistened with them. The princi-
pal fixed oils, are olive, croton, palm, cocoanut and linseed oils.

3. Voldtile oils give a peculiar flavor to plants, called aromatic.
They are obtained by distillation of leaves, or by expressing
them from the rinds of certain fruits, such as orange, lemon, hur-
gamot, etc. Like the fixed oils, they burn with a clear, white
flame. The principal volatile oils, are oil of turpentine, lemon,
anise, juniper, camomile, caraway, lavender, peppermint, rose-
mary, camphor, cinnamon, cloves, sassafras, mustard and bitter
almonds.

4. Resins are the juices of plants, such as exude from pines
and balsams; they are generally solid, brittle, and without taste.
The resins are well known, under the names of rosin, copal,
shell-lac, mastic, dragon's blood, guaiacum, etc. The uses of
these are well known. Copal is the basis of all varnishes.

5. Gum-resins are the hardened juices of several species of
plants, which, when cut, give out a milky juice, more or less
thick ; these are numerous, and many of them are valuable
medicines. Among them are aloes, asafcEtida, ammoniac, gal-
banum, gamboge, myrrh, olibanutn, opium, etc.

Aloes are obtained from several species of trees, especially
the aloe vulgaris, from the leaves of which it exudes when cut
It is of a reddish-brown color, and of an intensely bitter taste.

Ammoniac is obtained from the dorema ammoniacum, and is
used in medicine, but is the least powerful of all the fcetid gums.

Asafcetida is obtained from ferula asafatida, a naiive of Per-
sia ; it exudes fi-om the roots when cut, in the form of a milky
juice. Its taste is acrid and bitter ; its smell strongly alliaceous
and foetid. It is employed in medicine, especially in cases of
hysteria, asthma and hooping-cough.

Galhanum is obtained from the plant Galbanum officinale, a
native of Persia ; its taste is acrid and bitter, and its smell pe-
culiar. It is used in njcdicine for similar purposes with am-
moniac, but acts widi less energy than asafcetida.

Gamboge is obtained from a tree of Siam, and also of Ceylon ;
but the s{)ecies is doubtful. It is sold in commerce, under
three forms, pipe, cake and lump gamboge. It is employed in
water-colored painting, forming a i)urc and fine yellow. It is
also used in medicine as a cathartic.

Myrrh is obtained from the balsamadendron myrrha ; a tree
which grows in Arabia and Abyssinia. It exudes from the
tree in the state of a yellowish-white liquid, which soon liar-

NEUTRAL SUBSTANCES. 123

dens into a brittle solid, of a transparent, reddish-brown color,
and of a bitter and aromatic taste. It was known and used by
the ancients. In medicine, it is considered as a tonic. The
alcoholic tincture is used as a wash for the teeth.

Olihanum is the frankincense of the ancients. According to
Lamark, the Arabian variety is obtained from the amysis gilead-
cn5i5,. while Mr. Colebrook derives the Indian olibanum from a
large tree growing on the mountains of India, boswella serrata.
It is a brittle, white-yellow substance, of an acrid and aromatic
taste, and, when burnt, diffuses an agreeable odor, on which
account it is much used as a perfume.

Opium is a sedative gum-resin, which exudes from the heads
of the papaver somniferum, or poppy, great quantities of which
are used in medicine. It is also taken in large quantities as a
stimulant, in which case it is highly poisonous.

Class IV. Neutral Substances are those vegetable principles
which possess, neither the properties of acids nor bases, and
which, so far as is known, do not combine in definite propodions*
with other substances. Under this class are arranged a very
great number of useful substances. Those that are of particu-
lar interest to the agriculturist, may be included under the
following heads : sugars, amylaceous substances, gums, gluteiwus
svhstances, caoutchouc, extractive, and bitter principles.

I. Sugar (Ci2HioOio=]62) is a term applied to substances
characterized by their sweet taste. It is found generally in
the juices of plants, from which it is extracted by boil-
ing or evaporation. The sap of common sugar is obtained from
the sugar-cane (arundo saccharifera), the sugar-maple [acer sac-
charinum), and from the beet-root. This latter source of sugar,
was introduced into France by Bonaparte, during the war be-
tween France and England, and in the year 1 827, the quantity
manufactured was 2,650,000 lbs. The modes of making sugar,
derived from these sources, are various, and can only be alluded

* Most bodies, as the acids and alkalies, combine with other bodies
in definite proportions ; that is, definite quantities of one body combine
with definite quantities of another body, to form a third body. See
Introduction. But there are also a large class of bodies, both organic
and inorganic, which do not observe this law, and are said to unite in
indefinite proportions. Water and sulphuric acid, for example, will
unite in all proportions. Most substances which are held in solution
in water, unite with it in indefinite proportions, up to the point of satu-
ration; such as salts, sugars, gums, etc.

124 BIOLOGY OF PLANTS.

to in this place. When the sugar-cane is used, the green canes
are ground in a mill, and the juice evaporated or boiled.

The sugar-maple is tapped, and the juice received in buck-
ets or troughs, and then boiled until the water is all evaporated.
The beet* is sliced and pressed to obtain the juice. Many
other vegetables contain sugar, as the sap of the birch, butter-
nut, elm, and a great variety of trees ; but only those which
have been mentioned are employed for this purpose to any con-
siderable extent. It is a substance of universal consumption.

Liquid sugar is distinguished from common sugar, by the
fact, that it is incapable of a-ijstalb'zation. It exists in various
fruits and vegetable juices. It constitutes a considerable por-
tion of the molasses in the sugar of the cane. It exists also in
the grape, peach, apple, and other fruits.f

Zea Maiz, or Indian corn, also contains liquid sugar. Sugar
of grapes is not so white as connnon sugar, but it crystallizes
much more readily.

Manna was long regarded as a substance which fell from the
heavens, until it was found to exude from several trees, of which
a species of ash [fraxinus ornus), found in Sicily, is the most
productive. Manna has the form of oblong globules, of a yel-
lowish-white color, and is used in medicine. A substance
called mannite, or mushroom sugar, is similar to manna.

Sugar of liquorice is obtained from a plant growing in Spain.
The root is the common liquorice-root, and the black balls, sold
under the name of liquorice-balls, is the sugar.

2. Amylaceous substances include common starch, hordein,
lichnin, inulin, lignin, diastase, etc.

Common starch is secreted in most of the grains, the potato,
arrow-root, tapioca, sago, and, in small quantities, in nearly all
trees, seeds and fruits. When wheat-flour is formed into paste,
held under a stream of water, and kneaded until the water
runs off clear, a tough substance remains called gluten, while
there is deposited in the water a white sediment, which is
known as common starch.

Arrow-root is a very pure starch, extracted from the root of
the maranta arundinacea, a plant which is native in South
America.

Tapioca is also a very pure starch, obtained from the root of
a South American i)lant, iatropha marihot. The roots ai'c sub-

* Thompson's Organic Bodies, p. G"-20. Chaptal's Ag. Chemistry.
Child's Beet Sugar. t Prout.

NEUTRAL SUBSTANCES. 125

jeoted to pressure, and a juice extracted, which yields it in the
greatest abundance. It is a fine white powder, destitute of
taste and smell, and very much resembles starch.

Lignin (Ci5H'OOio=180.) This name is given to the fi-
brous portions of wood, which remain after digesting common
wood in water, muriatic acid and alkalies. It constitutes the
skeleton of the trunk and branches of trees. The quantity of
lignin varies in different kinds of wood, but generally there are
96 parts in 100. Sulphuric acid converts it into sugar, and
potash into ulmin. It is the substance which remains, when
wood is converted into charcoal, or rather it is the lignin which
is converted into charcoal by heat. It may be made into ex-
cellent bread. The inner bark of flax and hemp, and the
fibres of cotton, are probably the same substance. It is by far
the^ most abundant substance in vegetables.

Fimgin is a peculiar vegetable principle derived from mush-
rooms, and approaches in its chemical character closely to
woody fibre.

Diastase is a substance obtained from malted barley, and ex-
ists in the seeds, and also in oats and wheat. It has the pro-
perty of converting starch into sugar, and is used in the pre-
paration of dextrine, a substance employed for raising bread. It
is supposed to be the peculiar principle of ferments, and hence
its great use in culinary operations.

3. Gums are the exudations of several trees, such as the
plum, peach, apple, cherry, etc. but the principal gums are gum
arable, from the acacia, vera and arabica, and gum Senegal, from
acacia Senegal.

Lintseed, when macerated in water, is converted into mucil-
age, and when this is evaporated to dryness, it leaves a trans-
lucent matter behind, similar to gum. The different kinds of
gum are classed by Thompson under three vegetable principles,
arabin, bassorin and cerassin. Gum arable is principally compo-
sed of arabin, and is well known in the shops. Gum Senegal is
of similar composition. Mucilage of lintseed is different from
the preceding, but one part of it contains arabin.

Gum Bassora,gum iragacanth and gum kuteera, contain bassorin^
and are articles of commerce. These gums are used by calico
printers. The gum from the cherry, apricot, plum, peach and
almond tree, contain cerasin, which is the cause of their insolu-
bility. Many of the gums are easily soluble, and are used for
varnishes. They are also used in medicine to a considerable
extent.

II

126 BIOLOGY OF PLANTS.

Calendulin is a peculiar principle found in the marigold ; it
is a yellowish, translucent, brittle substance.

Saponin is another peculiar principle, found in a root which
grows in Greece and eastern countries ; it may be used for
soap.

4. Glutinous substances. When wheat-flour is kneaded into
paste with a little water, it forms an elastic, soft and ductile
mass. When this is washed under a stream of water until it
runs off colorless, there remains a tough, elastic substance, of a
gray color, called gluten. It was discovered in 1742, by Bec-
caria, an Italian philosopher. It has scarcely any taste, and
adheres tenaciously to most bodies with which it is brought in
contact. It is the substance which renders bread tough, and
enables the dough to rise by ferments. It exists in all kinds of
grain, and their value depends upon its quantity. Modern
chemists hiive resolved it into four distinct principles, albumen,
emulsin, mucin and glutin.

Vegetable albumen is obtained by digesting the gluten of wheat
in alcohol, until everything soluble is taken up. It is a bulky
substance of a greyish color, soluble in water, and is the sub-
stance in the seed, which takes an important part in germina-
tion.

Emulsin (C'^^H^SN^O^) is found principally in almonds, and
resembles starch, when dissolved in water. It has the pecu-
liar property of decomposing amygdalin, and of forming hydro-
cyanic acid, and the volatile oil of bitter almonds.

Mucin is taken up by hot alcohol, when the gluten of wheat
is put into it. It burns like animal matter, and is more soluble
than gluten.

Glutin (C^J^H'^'NiO^) is also taken up by boiling alcohol with
the gluten of wheat, and is obtained after precipitating all the
mucin. It is a yellow, translucent substance, almost insoluble
in water, and generally exists in wheat in connection with
starch.

Zein is a name given to the gluten of zea mais, or Indian
corn. It differs from the gluten of wheat by containing less
nitrogen.

Viscin (C^^WK)'^) is a soft elastic substance, of a brown
color, identical with bird-lime. It adheres firmly to the fingers
like glue, and exists in several species oi' acacia.

Pollenin (C'^H^OOI^) is derived from the pollen of the pinus,
abies and sylvtstris, and is sui)j)osed to characterize every spe-
cies of pollen.

NEUTRAL SUBSTANCES. 127

Lea-umin is a vegetable principle, found in the fleshy cotyle-
dons of all papilionaceous plants, such as peas, beans, etc. and
seems to be intermediate between gluten and vegetable albu-
men.*

Amygdalin (C^^^H^CN^O^S) is found in bitter almonds.

5. Caoutchouc is obtained from the milky juice of several
species of trees in South America, and in the East Indies. It
is is well known as India-rubber.

6. Extractive, The term extractive is now restricted to what
is obtained by macerating vegetables in water, and evaporating
the infusion to dryness. There is a great variety of these ex-
tracts, and they are used extensively in medicine, in which case
they are generally preserved in alcohol.

7. Bitter Principle. Many vegetable substances have an ex-
tremely bitter taste, and, on that account, are employed in medi-
cine. This is the case with the roots of the quassia gentian,
hop, camomile, worm-wood, etc.

The following are some of the most remarkable bitter sub-
stances which have been examined.

Quassite, obtained from the quassia amara and excelsa. Gen-
tianUe, from the seeds of the gentiana lutea. Cytisite, from the
seeds of the cytisus laburnum. Bryonite, from the root of the
Bryonia alba, or white bryony. Centaurite, from the leaves of the
centaurea benedida, or blessed thistle, ^^thanitite, from the cydor-
tnen Europeum, or sow-wort. Bitter principle of wormwood, trora
the artemisia absynthium, or worm-wood. Colocynthite, from the
cucumii colocynthii, or colocynth of pothecaries. Bitter principle
of aloes. Xanthropicrite. Berbente, from the bark of the com-
mon barberry, berbtris vulgaris. Lupinite, from the seeds of the
lupinus albus. Phloridzite, from the bark of the apple, pear,
cherry and plum tree.

It would be nearly useless to enumerate any more substan-
ces, as the peculiar products of vitality, for but little more can
be done in this work, than to mention their names. These are
mostly technical and unintelligible to the farmer. Perhaps too
many have already been inserted. The object is simply to give
the reader, some idea of the great number of compounds, which

* There are found in animal bodies three substances, which appear
to be identical with gluten, vegetable albumen and legumin ; they
are casien, the curd of cheese ; albumen, or the white of eggs ; and
fbrin, the substance which constitutes the muscular fibre of animals
It is probable, that these substances are derived by animals from vege-
tables. They contain large quantities of nitrogen, and hence th«ir
use for manure-

128 BIOLOGY OF PLANTS.

have been found in the vegetable kingdom, and which cannot,
with but few exceptions, be formed h}^ any known chemical
agents. This enumeration will perhaps lead some scientific
farmers to examine more fully the vegetable principles, and to
study in works where they are found fully described, their cha-
racters and uses.

It jnay, however, be useful, and much more intelligible to the
common reader, to describe the sources of several articles of
food and of medicine, as they exist in the roots, wood, bulbs,
leaves, fruit, or seeds of plants.

I. Roots. The principal roots, employed in medicine and
the arts, are the following.

1. Beet-root {beta vulgai'is). There are two varieties, the red
and the white beet. This is a well known vegetable. It con-
tains from 5 to 10 per cent, of sugar, generally from 8 to 9 per
cent. ; hence its use for this purpose.

2. Cairot [dauciis carota). This is also a well known root. It
is used for fattening cattle, and is preferable to the beet for that
purpose. It contains sugar, and a peculiar principle, called
caratin.

3. Rhuharh [rheum plamatum, ausfrale, undulatum, etc.) Three
varieties of rhubarb are known in commerce, Russian, Turkey,
East India or Chinese rhubarb. It is a yellow root possessing
powerful purgative properties, for which it is used in medicine.

4. Rattle-snake root {polygala senega), is a native of Virginia,
and is employed by the Indians as a cure for the bite of the
rattle-snake. The peculiar vegetable principle upon which this
effect depends, is called senegin.

5. Jalap [Jpomea jalappa), is a well known active cathartic. It
is a native of Mexico, but the best jalap comes from Vera Cruz
and South America. The active properties are supposed to be
due to the resin which it contains.

6. Gentian [gentiana lutea), grows in the mountains of Swit-
zerland and America, and is a bitter root, yielding to water an
extract, which produces intoxicating effects.

7. Valerian {Valeriana ojficinalis), is a root much used as an
anti-spasmodic in epilepsy, etc.

8. Horse-radish {cochlearea aimorica), is a root of an acrid
taste, which is due to a small quantity of volatile oil.

9. Siveet-Jlag {acorus calamus), contains a volatile oil, inuline,
gum-extractive, resin, with phosphate and muriate of potash.

NEUTRAL SUBSTANCES. 129

10. Ipecacuana {callicocca ipecmuand), common ipecac, is the
root of a plant which grows in Brazil. The root is about the
thickness of a qnill, and varies considerably in color. When
pounded, it forms the mildest and safest emetic.

11. Sarsaparilla {smilax sarsaparilla), is a native of South x\mer-
ica, and is used in medicine in certain chronic diseases, and in
syphilis.

12. Ginger [amomum zingiber), is a plant found in India, and
well known to the ancients. It is a whitish root, but when
powdered as in common ginger, it is yellowish. This root
makes a very delicate preserve.

13. Pomegranate tree [punica granatum),has been employed in
medicine. It contains a substance similar to mannite, which
has been called grenadia.

14. Crameria ratanhia is a root found in South America, and
yields a powerful and safe astringent matter, used in njedicine.
The active principle exists in the bark of the root.

II. Bulbs are the tubercles connected with the roots of
vegetables, analogous to buds. The following are the prin-
cipal bulbs or tubers,; which are used for food, in medi-
cine, and the arts.

1. Potato. This is the bulb of the solanum tvherosum, which
is found wild in the mountains of Chili. They contain but
little nitrogen. They also contain the poisonous alkali, so-
lenin, which exists in the epidermis when they begin to germi-
nate. They are generally composed in one hundred parts, of
eight parts of fibrin, ten of starch, one of gum, acids and salts,
and eighty-one of water. Their uses as food are well known.

2. Jerusalem artichoke is a bulbous root of the hdianthus tube-
rosus, a South American plant. It is very productive, of a
sweetish taste, very watery, and very valuable, as they will grow
on a light soil, and yield abundantly without much cultivation.
One acre sometimes yields sixty or seventy tons. It is singular,
that this valuable root is not more cultivated.

3. Garlic is the bulbous part of the root of the allium sativum.
It is found in Sicily, is remarkable for its strong smell and taste,
and was celebrated by the ancients, both as an article of food,
and as a medicine.

4. Onion is the root of the allium cepa^ a well known vegeta-
ble, used as food.

5. Squill is the bulb of the scUla nmritima a native of Spain,

11*

130 BIOLOGY OF PLANTS.

Sicily and Syria. Its bulb is nearly the size of a human head,
is shaped like a pear, and formed of fleshy scales. It has no
smell, but its taste is bitter, nauseous and acrid. It is used in
medicine to excite nausea and vomiting.

6. Saffron {colchicum autumnale) is used in medicine for the
gout. The tube is egg-shaped, and covered with a brown
membranous coat. The recent bulbs have no smell, but are
bitter, hot and acrid to the taste. It is poisonous.

III. Woods. The wood of different trees differs but little
in composition; generally about forty-eight or forty-nine parts
of carbon, six of hydrogen, and forty-four or forty-five of oxy-
gen, are found in one hundred.

The vegetable fibres in herbaceous plants are similar to the
wood of trees. Of these, hemp, flax and cotton are the most
important, because of their use in the arts. These sub-
stances, however, might, with equal propriety, be regarded as
the inner bark.

Fldx. The fibres of flax are " transparent, cylindrical tubes,
articulated and pointed like a cane." It was known to the an-
cients, and has been an article of universal consumption.

Hemp is precisely similar in composition with flax, but has
a coarser fibre.

Cotton is the soft down which envelopes the seeds of differ-
ent species of gossypium, from which plant the cotton of com-
merce is procured. " The fibres of cotton are transparent, glas-
sy tubes, flattened and twisted around their own axis." By
this test the^ne linen of Egypt is found to be linen, and not cot-
ton, as some interpreters of tlie Bible have supposed.

" Paper is prepared from hemp, cotton and linen rags. These
rags are bleached and reduced to an impalpable pulp." This
pulp is spread equally on a wire sieve, and the paper placed
upon cloths to dry ; after which it is sized and pressed.

IV. Leaves. The leaves of plants much resemble each
other in appearance, but contain various vegetable principles.

1. Senna is the leaf of the cassia acuiifolia and ohovata, na-
tives of upper Egypt and Nubia. It is a valuable cathartic.

2. Belladonna is tlie dried leaves of the atropa belladonna, or
deadly night shade. It is poisonous, but used in medicine.

SEEDS AND PLANTS. 131

3. Tobacco is formed from the leaf of the nicoliaiia tahacum, a
native of Tabaco in Mexico, from which it receives its name.
It is a well known, and much used narcotic poison. It con-
tains at least eighteen different substances. IsTicotina is the
cause of its poisonous effects.

4. Fox-glove, the digitalis purpurea, is a well known vege-
table, the leaves of which were introduced into medicine by
Dr. Withering.

5. Tea is composed of the dried leaves of the thea bohea, and
thea viridis, natives of China and Japan. The different varieties
of tea, are all derived from these two species. The leaves of
this plant are not fit for use, until the shrub has vegetated three
years. The leaves are collected and exposed to the steam of
boiling water, and every leaf is then rolled up with the hand,
put upon plates of copper, and held over the fire, until they are
shrivelled. To this heating process tea owes its peculiar flavor.
Its uses are well known. It is a powerful stimulant, acting up-
on the nervous system, and producing an exhilarating effect.

6. James' tea is the leaf of the ledum latifolium, a native of this
country.

7. Paraguay tea is the leaf of a native plant of South Amer-
ica, of the holly genera, and is used as a tea. It is a stimulant,
and, if used in excess, occasions intoxication and delirium, tre-
mens.

8. Isatis tinctoria, or woad, is the plant from which indigo is
olbtained.

9. Asparagus officinalis is a valliable vegetable, the young
shoots of which are used for food.

V. Seeds and fruits constitute the most important articles
of food. They contain all the elements necessary for the sup-
port of animals.

1. Wheat is the seed of the triticum hybernum, winter wheat,
and T. aestivum, or summer wheat, the most important of all the
smaller grains. Two or three other species have been cultiva-
ted. Its properties and uses are well known. A sample of
French wheat, analyzed by Vauquelin, yielded seventy-one parts
of starch, ten of gluten, five of sugar, three of gum, and ten of
water in one hundred.

2. Rye is the grain of the secale cereale. It is subject to the
disease called ergot, which is a species of fungus plants, of a
long, black appearance, blunt angles, and about one inch in

132 BIOLOGY OF PLANTS.

length. By some the ergot is regarded as the effect of an in-
sect. This substance is a violent poison. Rye is similar to
wheat in composition, but contains less starch and gluten.

3. Oats are the seeds of the avena saliva, and are a valuable
fodder for horses. In some countries, as Ireland, tiie oat is em-
ployed for bread.

4. Barley is the seed of the hordeum vulgare, and is used for
brea<l, malt liquors, and for obtaining ardent spirits.

5. Rice is the seed of the orysa saliva, a well known article
of food, especially in warm countries.

6. Maize or Indian corn. The zea maize is a native of this
country, but is now cultivated in Europe, and is one of the most
valued of our grains. It is coniposed of starch eighty-four, zein
three, albumen three, gum two, sugar two, water six, in one
hundred.

7. Peas are the seeds of the pisum sativum, and constitute a
very nutricious article of food.

8. The small bean [viciafaba), is used as an article of food, and
also,

9. The kidney bean, {phaseolus vulgaris). They contain a large
quantity of animo-vegetable matter.

10. Lentiles [ei-vum lens), contain a larger quantity of animo-
vegetable matter than the kidney bean.

11. Orange {citrus aura.nlium), and {cilrus medica), are well
known fruits which are employed both in medicine and for food.

12. Cherry {prunus cerassus), are a cultivated fruit, of which
there are several varieties.

13. Almond, Peach and Apricot are quite different fruits, but
the trees are botanically identical {amygdalus communis).

14. Pear [pyrus communis), apple {pyrus malus), are too well
known to need description.

15. Gooseberry [ribes grossularia), Black currant (jR. nigrum).
Red currant {R. riibrum), are valuable acid berries.

16. Grapes are the fruit of tlie vilis vinifera, and are exten-
sively cultivated in France and the soutli of Europe, both for
the wine vv'hich their juice yields, and for raisins.

17. Mango is the fruit of the mangifera indica or domcstica^ a
native of Lidia. The fruit varies from the size of an apricot, to
that of a pear. Its skin is soft and smooth, the fleshy part of
the fruit is juicy, and has a very sweet and acidulous taste. It
contains a great quantity of crystallizablc sugar, citric acid and
gum.

18. Pepper is the berry of the piper nigrum. Tiie unripe

SEEDS AND FRUITS.

133

berries are hlack pepper, and the ripe berries deprived of their
outer skins constitute white pepper. Oerstedt detected a matter
in tliis seed, which Jie called piperin, a peculiar vegetable prin-
ciple. It is composed of piperin C^"H'2"2O^N=340. An acid,
fatty matter, a volatile oil, extractive, gum, starch, bassorin in
abundance, a malate, and some other salts.

J9. Cubebs are the berries of the piper cubeba, and are simi-
lar in appearance to pepper-corns. They are of an aromatic
and acrid taste, and contain a peculiar vegetable principle
called cubebin.

20. Cayenne pepper is the fruit of the capsicum annuum, a na-
tive of India, but cultivated in the West Indies. The following
is the analysis of Braconnot : 100 parts contain of

Starch 9.

A very acrid oil 1.9

Wax, with red coloring-matter 0.9
Gum of a peculiar nature

Animalized matter 5.0

Citrate of potash 6.0

Lignin 67.8

6.0 Muriate & phosphate of potash 3.4

100.0

The acrid oil gives it its peculiar bitter and burning taste. It has
been called capsicin. Cayenne is a well-known spice, and is
much used in the preparation of Thompsonian nostrums.

21. Jamaica pepper (pimento), the fruit of the rmpius pimento,
resembles bladk pepper, and is prepared in the same w^ay from
the unripe berries. Their odor and taste resemble a mixture of
pepper, cinnamon and cloves. The following is the analysis of
Bonastre, of 100 parts.

3.2
8.0
1.6

16.

1.9
3.

Volatile oil

5.

Resinous matter

Soft green resin

2.5

Extract containing sugar

Solid fat oil

1.2

Malic and gallic acids

Extract containing tannin

39.8

Lignin

Gum

7.2

Ashes containing salts

Brown coloring-matter

8.8

Moisture

98.2

22. TVxmanncfe' consist of the pulpy matter which fills the
pods of the tamarindus Indica. It is a well known sweet-meat,
brought to this country preserved in sugar. It consists, ac-
cording to the analysis of Vauquelin, of

Supertartrate of potash

300

Tartaric acid

144

Gum

432

Malic acid

40

Sugar

1152

Feculent matter

2880

Jelly

576

Water

3364

Citric acid

864

9752

134

BIOLOGY OF PLANTS.

23. Juniper henries grow on a small shrub {juniperus commurtis)
in Scotland. They contain a peculiar volatile oil, which im-
parts its peculiar flavor to Dutch gin, in the manufacture of
which they are highly valued.

24. Anise is the seed of a plant [pimpinella anisum) cultivated
in Spain and Malta. The seeds have a peculiar aromatic smell,
a pleasant sweetish taste, and are used in medicine,

25. Mustard. There are two species of this plant found in this
country ; the sinapis nigra or black mustard, and the sinapis al-
ba or white mustard. The composition of both is similar.
They contain a peculiar principle, called sinapin (C^'^H^SQ^ and
2 equivalents of sulphur =268). The white mustard, according
to John, is composed as follows : of an acrid, volatile and a
yellow fixed oil, brown resin, gum, lignin, albumen, phospho-
ric acid and salts. Mustard acts as a powerful excitant. Its
uses are well known. White mustard has been a celebrated
remedy for dispepsy.

26. Cocoa-nut. This is the fruit of a species of palm [cocos
nucifera). The kernel contains a quantity of fixed oil, which is
used m India for lamps. The fibres of the outer coat are
formed into excellent cordage. It contains within, a milky,
sweetish, saline fluid.

27. Cucumber. The common cucumber {cucumis sativus) is
composed of the following substances.

Water 97.13

Substances similar to fungin 0-53
Soluble vegetable albumen 0.13
Resin 0.04

Extractive vi^ith sugar 1.66

Phosphate of lime and of pot-
ash, phosphoric acid, am-
moniacal salt,amalate, sul-
phate and muriate of pot-
ash, and phosphate of iron 0.5
lUO.OO

28. Thorn-apple [datura stramonium) is too well known to
need description. It has narcotic properties, similar to bella-
donna.

29. JVuimeg is the fruit of the myristica moschata, and is much
used as an article for seasoning food. It is a native of the Mol-
lucca Islands. The covering of the nut is called mace. It has
been analyzed by M. Bonastre, and consists, in 100 parts, of

0.8
56.
5.

TooT

Fat butyraccous oil

31.6

Acid

Volatile oil

6.0

Lignin

Starch

2.4

Loss

Gum

1.2

DEFINITIONS AND DESCRIPTIONS. 135

30. Coffee bean is the fruit of the coffcea Arahica, and is in
general use for the manufacture of coffee. The tree is a native
of Arahia, but is extensively cultivated, both in the East and
West Indies. It contains a peculiar principle called caffein
(C4H2NO=48.5). According to the analysis of Hermann, the
coffee bean, from Martinique, contains

Resin 68. I Lignin 11386

Extractive 310. Loss 12

Gum 144.

1920

31. Hops ave obtained from the humulus lupilus, and are em-
ployed extensively in the manufacture of beer and ale. The
hop is a dioecious plant, the female alone bearing fruit. It is
a valuable plant, and was introduced into England in the reign
of Henry the VIII.

32. Dates are the fruit of the palm, [pTicznix datilyfera^) and
constitutes an important article of food in several warm coun-
tries. It has a sweet taste, and contains a large quantity of
sugar.

This catalogue of fruits and seeds, and other products of the
vital principle, might be increased ; but a sufficient number
liave been noticed here to give the reader some idea of their
number, variety, properties and uses. They are intended chief-
ly, as a convenient reference to those who may not have access
to better sources of information.

There are several other simple bodies contained in vegetables
besides oxygen, hydrogen, carbon and nitrogen ; but as they do
not, by their combinations, form the peculiar products of the
vital principle, they are not noticed in this place. They will
more properly come under review in the next two sections, which
treat of the source and assimilation of the simple substances
which enter into the composition of plants. It should also be
remarked, that those substances which nourish vegetables, are
often derived from organic bodies, and that many compounds
are classed a$ organic, simply because they are derived from
organic bodies. But they are the products of death or decay^
not of life.

Sect. 2. Dejinitions and Descriptions. — Source and as-
similation of the Organic Constituents of Plants.

1. Humin is a substance found in the soil. It is composed
of carbon, hydrogen and oxygen, and is similar to woody fibre.

136 BIOLOGY OF PLANTS.

In fact it is wood partially decayed. It is insoluble in water,
but is converted by the agency of water, air or alkalies, into

2. Humic acid, which is identical in composition with it. Hu-
mic acid is a brownish-black substance, floculent when first pre-
cipitated, and soluble in 2,500 times its weight of water, and
becomes less and less soluble the longer it is exposed to the
air. It is composed, according to Sprengel, of carbon 58. , hy-
drogen 2.10, and oxygen 39.90 in 100 parts. Boullay gives the
composition of g-e?c acii/, which is identical with humic acid.
Malagutti gives nearly the same composition.

Boullay. Malagiitti

Oxygen 55.70 or 15 atoms

Hydrogen 4.81 15

Carbon 38.49 30

Oxygen 57.48

Hydrogen 3.76

Carbon 37.36

yy.60

Hence its composition may be represented by C^^VL^^O^^==oy
about 58 per cent, of humic acid is carbon.

3. Crenic acid, from krene the Greek word for fountain, is
composed, according to the analysis of Hermann, of C^'H^^NO^.
When pure it is of a yellow color, quite transparent, with no
tendency to crystallize. It has no odor, but its taste is sharp, at
first acid, and afterwards astringent. When in solution the
astringent taste alone can be perceived. It is excessively soluble
in loater and alcohol. It combines with lime, and forms the cre-
naie of lime, which is soluble in water, and the subcrenate of
lime which is insoluble. The crenates of potassa, ammonia and
soda, resemble extracts of a yellowish color, very soluble in
water, and in weak alcohol.

The crenate of magnesia is readily dissolved in water, but the
neutral crenate of alumina is insoluble, while the subsalt is solu-
ble. The crenate of iron is also soluble in water. Hence, as all
these substances are found in the soil, and nearly all are solu-
ble in water, they nuist enter the organs of plants with that fluid.

4. Jijjocrenic acid is formed from the crenic, by simply ex-
posing the latter to the air. Its composition niay be represent-
ed thus: C^^H^'^N^O^. It is a brown extract, possessing a
purely astringent taste. It is slightly soluble in water, is readilj'^
dissolved in crenic acid, and slowly in alcohol. As the crenic
acid always, upon exposure, changes into this acid, the existence
of the former appears essential to the i)roduction of the latter.

The ffy?ocrena/e.s of potassa, ammonia and soda arc black, fria-
ble masses, and when soluble in water, are of a dark-brown

DEFINITIONS AND DESCRIPTIONS. 137

color. Those of lime, magnesia, etc. are of a yellow color, and
soluble in water ; but the subsalts are insoluble.

5. ^pocrenate of alumina, when neutral, is insoluble ; but
soluble when there is an excess of acid. Jlpocrenate of the pro-
toxide of iron is soluble, but the salt of the peroxide is insoluble
in water; hence this acid with its various salts are generally
soluble in water to some extent, and must be conveyed into the
organs of plants.

6. Extract of humus and glarin are brown matters composed
mostly of carbon, hydrogen and oxygen. The above substances
form the chief ingredients of vegetable vwuld, and pass into
each other in the changes which take place in the soil.

When plants are subjected to ultimate analysis, that is, re-
solved into their simple constituents, they are found to be
composed of carbon, oxygen, hydrogen and nitrogen, which
form the vegetable proximate principles ; together with phos-
phorus, silicon and sulphur ; the alkalies, soda, potassa, ammo-
nia ; the alkaline earths, magnesia, lime and alumina, and the
oxides of iron, and of manganese. The four simple substances,
which form the proximate principles, are called the organic^
and the remaining bodies the inorganic constituents of plants.

The simple bodies of which vegetables are composed, are,
of course, all or nearly all derived from a source foreign to
the plant ; for although the vital power, may combine these
simple elements, so as to form a great variety of different
compounds, it cannot create a single particle of matter. The
view which was formerly taken, that metallic oxides were the
products of the vital power, has no foundation, either in fact,
or in philosophy. Whence then do plants derive the mate-
rials, out of which, their vital functions build up their vegeta-
ble structure ? In what particular form do they enter the
organs of plants, and what are the changes which take place
in their assimilation ? These questions have been variously
answered, and some things are still matters of controversy. It
will be necessary to devote this and the following sections to a
12

138 BIOLOGY OF PLANTS.

full discussion of the theories of those chemists and physiolo-
gists, which are best entitled to confidence.

In the present state of our knowledge, it will be more use-
ful to present the arguments for and against the most favor-
ite theories, and to state the practical deductions which natu-
rally grow out of them.

I. Carbon. The most abundant substance in vegetables,
is carbon. From whence is it derived, and what are the
changes which take place in its assimilation ?

History. It has been the general opinion of agricultural
writers, that vegetable mould or humus is the principal source
of the carbon of plants ; and hence, the cause of the fertility
of soils.

Humus or mould is a brown substance, easily soluble in
alkalies, and but slightly soluble in water. It results from
the decomposition of vegetable matter, when subjected to the
agency of water and air, but its formation may be promoted
by the action of alkalies, alkaline earths, metallic oxides, and
in some cases by acids. Chemists have designated this sub-
stance by several names ; sometimes including all the decom-
posed organic matters of the soil under the term humus or
geine, and sometimes only the soluble parts of it. Berzelius,
in 1833, divided the organic matters of the soil into extract
of humus, geine and carbonaceous mould ; and in 1841 he
made the following division ; extract of humus, humic acid,
humin, crenic and apocrenic acids. Now the gci?ie of 1833 is
the hujnic acid of 1841. Dr. Dana calls all the decomposed
organic matter of the soil geine. This consists of two parts ;
that which is decomposed by, or is soluble in alkalies, and
which is a definite compound, he calls soluble geine, and as
it exhibits the properties of an acid, geic acid, answering to
humic acid ; and that which is insoluble in the same solvent,
he calls insoluble geine. He also admits the existence of
crenic and apocrenic acids.

Dr. C T. Jackson denies the existence of any such defi-

SOURCE OF THE CARBON. 139

nite compound as soluble gcine, but makes the substance so
called consist of crcnic and apocrenic acids, combined in part,
with bases forming in fact a mass of salts.

Liebig disregards all these different substances, and calls
the whole humus or humic acid. This geine or humic acid
of soils, appears to be identical in composition with a sub-
stance, noticed by Vauquelin in the bark of the elm, and
which is the product of vitality called ulmin, and ulmic acid.
It is in fact, elm-gum, or mucillage. It was also called humic
acid. But Berzelius regards the ulmic or humic acid of soils,
which is the product of decay or death, as different from that
which is the product of life. There are also several artificial
compounds, which are nearly identical with humic acid.
" Ulmin, humic acid, coal of humus and humin,^^ says Liebig,
" are names applied to different modifications of humus.
They are obtained by treating peat, woody fibre, or brown
coal with alkalies ; by decomposing sugar, starch, or sugar of
milk by means of acids ; or by exposing alkaline solutions of
tannic and gallic acids to the action of the air." The soluble
parts he calls huinic acid; and the insoluble, humin or coal
of humus. Liebig has attempted to show, that these artifi-
cial products, although they have received the same name,
humic acid, are as different in composition, as sugar, acetic
acid and resin ;* and that there is not the slightest ground
for the belief, that any one of them "exists in nature in the
form, and endowed with the properties, of the vegetable con-

* Thus the sulphate of potash and saw-dust, when fused form hu-
mic acid containing 72 parts of C in 100 (Peligot). Turf and brown
coal yield an acid containing 58 parts of C in 100 (Sprengel). Di-
lute sulphuric acid and sugar yield 57 parts of C (Malaguti). Muriat-
ic acid and sugar or starch yield 64 per cent, of C (Stein). Malaguti
states, that humic acid contains an equal number of equivalents of oxy-
gen and hydrogen ; but according to Sprengel, the oxygen is in ex-
cess, and Peligot estimates the excess to be 14 equiv. of oxygen to
6 of hydrogen ; but, Hermann makes the humic acid of soils to be
composed of 58 parts of C, 2.10 of hydrogen, and 39.90 of oxygen.

140 BIOLOGY OF PLANTS.

stituents of mould ;" that is, he denies the existence of these
substances in the soil, and that they exert the slightest influ-
ence upon vegetation. But with this exception of Liebig and
Raspail, all chemists admit the existence of humic acid in
the soil. It should be observed further, that the humic acid
of soils is constant in its composition, while that formed by
artificial processes, varies in the proportion of its carbon.

" Once for all," says Dr. Dana, when speaking of the hu-
mic acid of soils, " I consider ulmin, humus, geine, ulmic
and geic acid one identical substance, whether neutral or
acid, its constitution ever one and the same, subject to the
great law of organic chemistry, that proximate compounds
act as simple elements."*

But whatever name we give to this substance, whether we
regard it as a definite organic compound in the soil, gen-
erally united to oxides, forming in fact a mass of geates, or
as composed of several acids, which are also combined with
similar bases, forming crenates, apocrenates and humates, or
whether it is differently constituted ; it has been generally
believed to be the source from whence plants derive most of
their carbon.

There is one distinguished chemist, however, Liebig, who
has lately advocated the opinion, that the humus of soil does
not yield the " smallest quantity of carbon to plants," and
" that the only use of it is, to form a small quantity of carbonic
acid, a substance which exists in sufficient abundance in the
atmosphere, and from which alone, all the carbon is derived."
This theory, with others, will now be examined at length.

I Theory oj Liebig. According to this theory, the only
source of the carbon of plants, is carbonic acid, which is
found either in the atmosphere, and absorbed by the leaves
of plants, or is dissolved in water, and enters by the roots.
In both cases, the acid is decomposed in the leaves, by the

* For a full history of this substance, see Dana's Muck Manual,
p. 72 seq.

THEORY OF LIEBIG. 141

influence of solar light. This theory differs from others, only
in supposing, that all the carbon of plants is derived from the
carbonic acid of the atmosphere. All chemists and vegetable
physiologists fully agree, that a large portion of the carbon is
thus obtained.

Arguments in support of this theory. Liebig represents
humic acid or humus, as the only substance in the soil, cajja-
ble of yielding carbon to plants ; and, as it requires 2500 parts
of water to dissolve it, alkalies or alkaline earths must com-
bine with it, to render it soluble and capable of entering the
roots. Now this acid is a definite compound, and he attempts
therefore, to determine the exact quantity which will combine
with the inorganic base, which enter into the composition of
vegetables.

1. Suppose that the humate of lime, the most abundant
salt- of humic acid, is the source of the carbon. On the sup-
position that the lime remains fixed in the vegetable organs,
it is found by accurate calculation, that only Jg part of the
carbon, actually foupd in plants, could be introduced in this
way.

2. If we calculate the quantity of metallic oxides in wheat
straw, and the known quantity of humic acid required to sat-
urate them, we shall find, that the proportion of carbon intro-
duced by this means, will be as 1 to 17, or about y^ part of
the carbon which the straw actually contains.

3. Humate of lime, the most soluble of all the salts of hu-
mic acid, must first be dissolved in water, one part of which
requires 2500 of water for solution. Now if we calculate
the quantity of water which falls on a given surface, in one
season, and suppose all the water to enter the organs of plants,
the humate of lime which it would carry with it, would not
yield more than J^ of the quantity of carbon which is found
in the corn, grown on the same surface. But only a small
part of the water actually enters the roots of plants, and hence,

12*

142 BIOLOGY OF PLANTS.

the quantity of carbon introduced by this means, must be
much less.

4. Fertile land produces carbon in the form of wood, hay,
grain, and other kinds of growth, the bulks of which differ
in a remarkable degree, but the quantity of carbon yielded by
equal surfaces is quite constant. On the supposition that
the land is equally fertile, the w^eights of forest trees, hay,
beet root and rye, growing on an equal surface, are as 2650,
2500, 20,000, 2580 ; but when these several products are de-
composed, the actual quantity of carbon in each is about 100
parts; hence, the quantity of carbon is not affected by ma-
nure, as forest lands, meadows and cultivated fields yield the
same amount. These facts show that the humus of the soil
is not the source of the carbon*

Whence then is it derived? It is universally admitted,
that humus arises from the decay of plants. No primitive
humus, therefore, can have existed, for plants must have pre-
jeeded the humus.

Now, whence did the first vegetables derive their carbon]
and in what form is the carbon contained in the atmosphere ?
These two questions are easily answered, when we consider,
that the atmosphere contains carbon in the form of carbonic
acid, in nearly invariable proportions. The carbonic acid,
amounts,, constantly, according to Saussure, to 0.000415 of
its volume, or about y^V^y P^^^^ ^y weight, although several
causes are constantly tending to increase it. The respiration
of animals throws off immense quantities into the atmos-
phere. Great quantities are also evolved from volcanic dis-
tricts and from certain springs. It is liberated from limestone,
and other. carbonates, by chemical action; and, finally, the
process of combustion must very much increase the amount.
By this latter process, and by the respiration of animals, oxy-
gen is consumed ; but the atmosphere always contains the
same proportion of oxygen, why does not the oxygen dimin-
ish and the carbonic acid increase 1 simply because plants

THEORY OF LIEBIG.

143

absorb the carbonic acid, assimilate the carbon, and yield
back the oxygen to the atmosphere, and they must always
have done the same.

This remarkable property of plants has been demonstrated
in the most satisfactory manner by Priestley and Sennebier.
The power of decomposing the acid resides in the leaf, but
is exercised only when the leaf is exposed to the light. This
power is not dependent upon the connection of the leaf with
the stem, as leaves separated from the stalk, and exposed, in
an atmosphere of carbonic acid, to the solar light, readily ab-
sorb and decompose it ; but if the plant is immersed in an al-
kaline solution, which will prevent the carbon from being as-
similated, no oxygen will be emitted. Hence it appears, that
the life of plants is connected with that of animals, in a most
simple manner, and for a wise and sublime purpose. Plants
may live without animals, but animals must have organic
matter for their support. Plants purify the air, and furnish
an inexhaustible source of oxygen gas.

The orfy questions now are, whether there is a sufficient
quantity of carbonic acid in the atmosphere to supply the
wants of plants ; and if so, whether it is available ?

As to the quantity. We know the exact weight of the
whole atmosphere ; for every square inch, on the surface of the
earth, weighs 151bs., of which -jo^^-q part by weight is carbonic
acid. By this data, the quantity of carbon in the form of car-
bonic acid amounts to nearly 3000 billions of pounds ; a quan-
tity more than the weight of all the plants, and all the strata
of mineral and brown coal, which exist upon the earth. This
carbon is, therefore, more than adequate for all the purposes
for which it is required. The proportional quantity of car-
bon contained in sea-water,* is still greater.

That this carbon is available to plants, appears from the
fact that the winds, moving at the rate of sixty miles per hour,

* 10,000 volumes of sea-water contain 620 volumes of carbonic acid.

144 BIOLOGY OF PLANTS.

are constantly mingling the top and bottom air, and the car-
bonic acid of the northern regions is thus carried to the trop-
ics, where a luxuriant vegetation liberates the oxygen, and
sends it back again towards the poles. The leaves, also,
which are the organs of absorption, present a large surface, in
contact with which the acid is constantly brought.

5. As the most important function in the life of plants is
the separation of oxygen gas, no matter can be considered
nutritious, or necessary to the growth of plants, whose com-
position is similar to, or identical with, the vegetable products.
Thus starch, gum and sugar cannot be vegetable food, as
their assimilation would take place without the separation of
oxygen. Now humus, or decaying woody fibre, contains
carbon and the elements of water, without any excess of oxy-
gen ; hence it resembles one class of vegetable products, and
cannot, therefore, be assimilated and become the source of the
carbon.

6. The very nature of decay, that is, of the conversion of
wood and vegetable matter into humus, shows that carbonic
acid is the only source of the carbon. In the decay of woody
fibre, what are the chemical changes which take place ?
Oxygen is absorbed from the air, and carbonic acid is evolved.
The oxygen of the air combines with the hydrogen of the
wood, and the carbon and the oxygen of the wood are evolved
in the form of carbonic acid. If the oxygen of the air com-
bined with the carbon, so as to produce a genuine combustion,
the carbon of the woody fibre would in time be all removed.
But the proportion of carbon is greater in humus than in
woody fibre ; hence it is a process of oxidation, while car-
bonic acid is evolved; but after a while, the attraction of the
oxygen for the hydrogen is overcome by the attraction of the
carbon for the same substance, and the process of decay
ceases. The brown substance which remains is called
mould, and is the product of the complete decay of woody fibre.
Alkalies increase this tendency to decay, and acids retard it.

THEORY OF LIEBIG. 145

When the soil is stirred, it facilitates the introduction of oxy-
gen, which also hastens the process. How then does the de-
caying woody fibre act ? Simply by yielding carbonic acid :
and when any substance, as stagnant water, or the composi-
tion of the soil, arrests the process of decay by excluding the
air, then the carbonic acid is not yielded to the roots of
plants, and the leaves turn yellow and fall off.

7. Finally, that carbonic acid is the only source of the
carbon, appears from the fact, that in the " chemical trans-
formations " which take place in the process of assimilation,
the eifete, or excrementitious matters, which are thrown out
by the roots, contain a quantity of carbon, nearly or quite
equal to that which the humus yields in the form of carbonic
acid. This matter becomes humus, and is converted into
carbonic acid again, in the process of decay. Now when
these excretions are added to the carbon, derived from the roots
of plants and from their leaves, the quantity annually returned
to the soil, must be greater than that which is taken from it.
" A soil receives more carbon in this form, than its decaying
humus had lost in the form of carbonic acid." — L.

From all these facts, it appears evident that humus does
not nourish plants by being taken up and assimilated in its
unaltered state, but by furnishing a slow and lasting source
of carbonic acid. It should be remarked in this connection,
that it is only during the period of youth, that plants use
even the carbonic acid derived from the humus of the soil.
As soon as their organs are sufficiently enlarged, they de-
rive their carbon wholly from the atmosphere.

We have been thus particular in giving the leading argu-
ments by which this theory is advocated, because of the bold-
ness and novelty of the views which it contains, and also be-
cause it points out the most important source of the carbon of
plants ; and although it is not true, as we shall show, that
carbonic acid is the only source of the carbon, this theory
will aid us in determining what portion is derived from that
source.

146 BIOLOGY OF PLANTS.

Objections to the Theory of Liehig. The arguments
by which this theory is supported, are not all well founded ;
and if they were, they would not prove its truth, but would
furnish good reasons for the opposite opinion, that plants de-
rive a part of their carbon from other sources.

1. This theory does not give a correct view of the compo-
sition of humus. According to the recent analysis of Ber-
zelius, the humus of soils, as we have seen, is composed of
humin, extract of humus, humic, crenic and apocrenic acids,
and some salts. Dr. C. T. Jackson makes the humus of soils
consist of more than twenty substances, of which humic, cre-
nic and apocrenic acids are the most important. These sub-
stances are rich in carbon, containing from fifty to sixty per
cent. They are rendered soluble in water, by the action of
the oxygen of the air and of alkalies ; they must therefore en-
ter the roots of plants, and may be decomposed in the vege-
table organs, yielding their carbon, oxygen and hydrogen,
while the inorganic bases with which they were united, may
be returned to the soil as excretory matter. Thus, according
to the theory itself, and to other facts, the inorganic bases,
which Liebig supposes remmnjixed in the plant, may be the
means of conveying successive portions of carbon into the
vegetable organs. In fact the decomposition of salts by the
" catalysis of life" is the most important change which takes
place in the soil. The bases are thus let loose upon the hu-
mus, combine with it, and the salts may again be decom-
posed. Hence, a part of the carbon must be derived from
the humus of the soil.

2. But, on the supposition that no larger quantity of carbon
could be introduced, by means of humic acid or humates, than
the theory supposes, the conclusion is still unavoidable, that a
part of the carbon is derived from this source, or else, that large
quantities of carbon are taken into the vegetable organs and
again rejected, without being decomposed ; but in such a
case, they must act as poisons, and become a constant source

OBJECTIONS TO THE THEORY OF LIEBIG. 147

of injury. Of course, the richer a soil is in humus, the more
injurious must its effects be upon the crop !

3. This theory does not give a correct view of the quantity
of water in the soil. Rains are by no means the only source
of water. All vegetable bodies, according to Liebig, and
others, in the process of decay, yield carbonic acid and wa-
ter. For, although water is decomposed, it is but a small quan-
tity, compared with that which is formed by the union of the
oxygen of the air and the hydrogen of the vegetable matter.
From this latter source, not noticed by Liebig, a quantity of
water is furnished, sufficient to hold in solution a larger quan-
tity of humates, than the theory supposes.

This is a perfect answer to the assertion, that the rains do
not furnish a sufficient quantity* of water to hold the humates
in solution. In fact, it is highly probable, that the plants, on
an acre of soil, take up by their roots and transpire through
their leaves, a larger quantity of water, during any given time,
than falls during the same time upon an equal surface. But
if water dissolves any portion of the humates, it must be the
means of conveying to the plant a portion of their carbon.

4. This theory entirely overlooks the influence of living
plants upon the alkalies in the soil.

The vegetable, in connection with the soil and water, forms
a galvanic battery, by which the alkalies are eliminated.
These alkalies, coming in contact with humus or geine, ren-
der it soluble. This is a farther means of introducing hu-
mates into the organs of plants,t and hence a part of the car-
bon must be derived from this source.

5. "Vegetable and animial manures," says Berzelius, " be-
come changed, after a while, into crenic, apocrenic and hu-
mic acids, in order to supply what has been removed by the

* See Dana's Muck Manual, p. 225.

t See Dr. Dana's Letter to Prof Hitchcock, in the Final Report of
the Geology of Massachusetts. Also, Appendix to Liebig, 2d edit.

148 BIOLOGY OF PLANTS.

crops, which have been taken from the soil." Hence it would
seem, that these substances are the sources of a part at least
of the carbon, and that it enters mostly in the form of humates
{geates), crenates and apocrenates.

6. This theory is inconsistent with itself and with facts.
If, as Liebig contends, plants give out to the soil effete matter,
mostly composed of carbon, this matter cannot affect th e
succeeding crop ; for if all the carbon is derived from the at-
mosphere, the excretions will not be absorbed in larger quan-
tities than other matters, especially as they are nearly insolu-
ble. But Liebig and others admit, and experience seems to
prove, that the effete matters of one family, are injurious to
succeeding crops of the same family, but useful to those of a
different race.

On this theory the fertility of soils does not depend, in the
slightest degree, upon the quantity of vegetable matter, the
humus or geine ; a conclusion which is opposed to all experi-
ence on the subject. For it has been observed by every far-
mer, that vegetable substances are highly promotive of fertil-
ity, so much so, that it has long been the effort of farmers to
convert their soils into loams by the addition of these sub-
stances ; that is, by increasing the quantity of vegetable mould
or humus. A soil rich in humus or geine is generally fertile,
one destitute of it is wholly barren ; and the degree of fertility,
as will be fully shown in a future section, is very much in the
ratio of the soluble geine which the soil contains.

According to this theory, a continual course of cropping
ought to increase the quantity of carbon in the soil, especially
as the soil may be so constituted as to contain but little de-
caying humus to supply carbonic acid to the roots. But we
know that when afield has been cultivated for a long period, and
the crops all removed, it will, in the end, be reduced to abso-
lute barrenness ; and when we look for the cause, we find
the vegetable matter is mostly or quite removed. The effect
of manures, therefore, in keeping up the quantity of vegetable

OBJECTIONS TO LIEBIg's THEORY. 149

mould, and with it, the fertility, proves conclusively, that plants
derive their carbon from other sources than carbonic acid.
" A seed germinates in a soil in which no vegetable matter
exists; it sprouts vigorously, increases then slowly, grows
languidly at the expense of the air ; and the plant dies stinted
or immature."*

6. Finally, it appears upon a general view of the subject,
that although carbonic acid is absorbed by the leaves and
roots of plants, and is a source of a large quantity of their
carbon, yet other substances, rich in carbon, must enter
the roots of plants, must be decomposed, and their carbon
assimilated.

The fact, that the atmosphere contains carbon in sufficient
quantities to supply the whole vegetation of the globe with it,
does not prove it the only source. The fact, that the atmos-
phere is not, in time, filled with this acid, does not show that
plants must derive all their carbon from it, or else its purity
would be destroyed. There is a vast ocean of water which
is constantly absorbing carbonic acid. Growing vegetables are
acknowledged by all, to decompose a large quantity of it, and
thus to contribute to the purity of the atmosphere. And this
process is truly for a sublime purpose ; but yet, the necessity
of deriving carbon from the humus of the soil, is not, on this
account, wholly dispensed with.

This theory, then, must not be received in the absolute
sense, but only as showing, in a strong light, the principal
source of the carbon of plants ; while the nature of humus is
such, according to the theory itself, as to furnish abundant
ground for the opinion, that a part of the carbon is derived
from that source. Although it may be true, that the whole of
the carbon was originally derived from the atmosphere, it is
not true that any single crop derives the whole, directly, from
this source. ,.;,< . -

* Johnson's. Lectures.

13

150 BIOLOGY OF PLANTS.

The other sources, from which plants derive their carbon,
have already been pointed out. The humus of the soil is
composed mostly, as we have seen, of humic or geic acid,
crenic and apocrenic acids. These substances contain large
quantities of carbon, generally in the form of salts, which are
soluble in water. They must enter the roots with that liquid,
and yield their carbon to the plant.

TTie proportion of carbon derived from the atmosphere,
and from other sources, will depend upon the nature and
age of the plant; the quantity of food in the soil or the
air; climate; quantity of light, and similar circumstances.

We know, by the observations of every day, that fields
which are constantly covered with vegetation, such as pastures
and wood lands, increase in carbon. They must not only
take from the air nearly the whole which enters into their
substance, but they must also add to the quantity in the soil,
This certainly must be the case in peat swamps, where the
vegetable matter accumulates to a depth of several feet. But
tillage crops, as appears both from observation and experi-
ment, take more from the soil than they return to it. By the
carefully conducted experiments* of Boussingault, the quan-
tity of carbon, which plants derive from the atmosphere dur-
ing five years' rotation, was about two-thirds of what they con-
tained ; but it is evident, that a considerable quantity of car-
bon in the soil, must pass into the atmosphere in the form of
carbonic acid ; and hence the quantity obtained from the air,
must exceed two-thirds of the whole.t

* The principle, upon which the experiments were conducted, was,
to examine for a series of years, the quantity of carbon in the soil be-
fore the crop, the quantity in the crop itself, the quantity in the soil
after the crop was removed, and the quantity added in manure.

t On the supposition, that two-thirds of the carbon is derived from
the atmosphere, and if we allow one ton and a half to be tlie average
quantity of dried produce on an acre of surface, the quantity of car-
bon would be about 1100 pounds.

ASSIMILATION OF CARBON. 151

If any confidence can be placed in the quantity, which may
be conveyed to the vegetable organs, in the form of humates,
crenates and apocrenates, we should infer, that when these lat-
ter substances were abundant, more than one third might be in-
troduced by these means ; but when not abundant, much less
than that proportion of the whole carbon which the plant
contains, would be furnished from the soil. So far, then, as
the state of our knowledge enables us to come to any just con-
clusions, the sources of the carbon of plants are,

1. The carbonic acid of the atmosphere, which is the prin-
cipal source.

2. The humus of the soil, or the humates, crenates and
apocrenates, found in vegetable mould.

The precise quantity, from each of these sources, it is dif-
ficult to determine, as it will vary with circumstances ; hence,
we may conclude that plants, like animals, are capable of adapt-
ing themselves to their situation, and of obtaining, from one
or the other of these sources, the carbon which forms the
largest portion of their substance.

Theory of the assimilation of carbon. The changes wrought
in the vegetable organs, upon the substances which furnish
carbon to plants, are, as yet, mostly matters of theory.

We know, indeed, that carbonic acid and other substances
rich in carbon, are absorbed by plants, and that oxygen, ni-
trogen, and some other gaseous bodies, are exhaled by the
leaves and other green parts. But the carbon does not exist
in the plant in a pure state, but in combination with oxygen,
hydrogen and nitrogen, in definite proportions, forming the
vegetable proximate principles. How then is the carbon as-
similated ?

The process of assimilation may be illustrated by chemical
transformations, although the vital power, in its mysterious
operations, must be resorted to, in order fully to explain the
phenomena. " An organic chemical transformation, is the
separation of the elements of one or several combinations,

152 BIOLOGY OF PLANTS.

and their reunion into two or several others, which contain
the same number of elements, either grouped in another man-
ner or in different proportions."*

" Of two compounds, formed in consequence of such a
change, one remains as a component part of the blossom or
fruit, while the other is separated by the roots, in the form of
excrementitious matter. No process of nutrition can he con-
ceived to subsist in animals or vegetables icithout tlic separa-
tion of effete matters.^''*

A transformation must take place, whenever there is a
disturbance of the mutual attraction which subsists between
the simple elements of bodies. The elements arrange them-
selves, so as to give rise to new substances, either with or
without the separation of one of the elements of the compound.
" Hydrocyanic acid and water, for example, contain all the
elements of carbonic acid, ammonia, urea, cyanuric acid, cy-
anilic acid, oxalic acid, formic acid, melam, ammelin, me-
lamin, azulmin, mellon, hydromellonic acid and allantoin."*
All these substances may be obtained from hydrocyanic acid
and water, by various chemical transformations.

Suppose now, that carbonic, humic and crenic acids, were
to meet each other in the vegetable organs, either in the pure
state, or in the form of their soluble salts (and they must so
meet), their mutual affinities would be disturbed, and their
elements arranged, so as to form several, if not all, of the
vegetable compounds. Each organ would extract what food
was fitted for its sustenance. That is, one vegetable sub-
stance being formed, the remaining elements which are not
assimilated, would combine together and be rejected at once
as effete matter ; or by coming in contact with another or-
gan would pass through another transformation, and so con-
tinue on, until, being capable of no farther transformations,
the matter would be separated from the system by the organs
destined for that purpose. Thus, the useless matters rejected

* Liebiir.

ASSIMILATION OF CARBON. 153

by one organ, would furnish food for a second and a third.
The precise changes which take place, are not so easily detect-
ed, although some of them are easily deduced, from the known
character of the substances which meet ; thus, it is easy to
see, that woody fibre may be formed by the union of the car-
bon of the carbonic acid, with water, while the oxygen of the
acid, is separated by the leaves. This process may be ex-
pressed thus ; thirty-six equivalents of carbon derived from
thirty-six equivalents of carbonic acid, combined with twenty-
two equivalents of hydrogen and twenty-two of oxygen, de-
rived from twenty-two equivalents of water, form woody fibre,
with the separation of seventy-two equivalents of oxygen.
The oxygen which is separated, is probably derived fi-om the
carbonic acid, as there are just seventy-two equivalents in thir-
ty-six of acid, although a part may be derived from the water.

Such transformations are constantly taking place, dur-
ing the growth of plants, and the consequence is, that ex-
crementitious matters, of different kinds, are thrown off, as
unfit to nourish the system. Some of these contain an ex-
cess of carbon, others of hydrogen, and others still of nitro-
gen and oxygen. Some of the matter is gaseous, and is giv-
en off by the leaves ; some of it is liquid, and is ejected at the
roots; while part of the effete matter is solid, and remains in
the form of the outer bark. In this respect, there is a strik-
ing analogy between animals and vegetables. The kidneys,
liver and lungs of animals are organs of excretion. The kid-
neys separate all those substances, which contain an excess
of nitrogen ; the liver, those in which carbon is in excess,
and the lungs, those in which oxygen and hydrogen are most
abundant. The latter also exhale alcohol and the volatile
oils, when taken into the system ; hence these substances are
incapable of assimilation.

In the process of respiration, the oxygen of the inspired
air, does not enter into combination with the carbon in the
lungs, but combines with the hydrogen of the blood, while

13*

154 BIOLOGY OF PLANTS.

the carbonic acid is excreted or thrown off. The nitrogen-
ous substances are thrown out in a liquid form, by the urinary
organs, and the solid substances, by the intestinal canal.
Hence, nutrition in animal bodies is always attended by
excretions.* The same is true of vegetables.

The doctrine of transformations, thus given, may serve to
illustrate the general nature of assimilation, so far at least as
it can be done on strictly chemical principles. Some, as
Liebig would seem to convey the idea, that the agency of the
vital poiuer is not required in those changes, and that the ef-
fect may he fully accounted for on chemical principles. But
what chemical force, or what law known to chemists, can
cause thirty-six equivalents of carbon, twenty-two equivalents
of hydrogen, and twenty-two equivalents of oxygen, to com-
bine and form woody fibre ? We never see such compounds
formed, unless it Idc in the vegetable or animal organs ; and
this single fact shows conclusively, that some other pov/er
than affinity is at work to form such combinations.

We see no reason for rejecting the theory, that the vital power
of the plant may act by its catalytic force, and decompose bodies
which are external to the roots, causing one or more of their
elements to enter their organs, and to combine with substan-
ces already introduced, or previously formed. Such a view
is rendered highly probable, when we consider the fact, that
the living plant is a most powerful agent in decomposing the
soil, and obtaining the alkali which its wants may require.
Life is doubtless a powerful catalytic force in producing the
transformations which attend the process of assimilation.

II. Source of the Hydrogen of Plants. The source of the
hydrogen of plants is easily determined, because there are
but few substances which contain it in sufficient quantities to
supply the wants of vegetation. The chief sources of the hy-
drogen are the following.

* Some represent tlie clmnge to be a process of real combustion.
Others believe, that tlie absorbed oxygen unites with the carbon in the
course of tlie circulation.

SOURCES OF HYDROGEN. 155

1. Water, which is composed of eight parts of oxygen and
one of hydrogen. Water pervades the atmosphere in the
form of vapor, is deposited in dew or rain, and absorbed by
the leaves of plants. It is also taken in by the roots, and
forms a large portion of the sap. When we call to mind the
fact of its remarkable tendency to pass through transforma-
tions, there can be no doubt, but that it furnishes the largest
portion of the hydrogen of plants.

2. Ammonia is another substance which contains hydrogen.
It is always present in fermenting manures, and in the atmos-
phere. It must, like water, be absorbed by the leaves of
plants, and by their roots ; and as it is similar to water in the
facility with which it is decomposed, it must furnish hydro-
gen to the vegetable products. Hence one reason for its
powerful effects upon vegetation.

3. Light carbureted hydrogen is found in the atmosphere
and in the soil, and may be the source of a part of the hydro-
gen of plants ; although it is doubtful, whether they draw
upon this source, when there are at hand, more abundant and
far better sources. It may, however, be decomposed in
the air by electric discharges, and resolved into carbonic
acid and water.

4. Geine or humus of soils contains hydrogen, in the form
of humic, crenic and apocrenic acids. These substances en-
ter the organs of plants, and may yield a large portion of the
hydrogen. Liebig derives the hydrogen wholly from water.

III. Source of the Oxygen of Plants. Oxygen may be de-
rived from several sources.

1. The atmosphere contains twenty-one parts of oxygen in
one hundred, and as the leaves of plants are known to absorb
it (p. 75), they obtain a part of their oxygen from this inex-
haustible source.

2. Water contains eight parts in nine of oxygen. This is
absorbed both by the leaves and roots of plants in large
quantities, and is doubtless the principal source of the oxygen,
as well as the hydrogen of vegetable bodies.

156 * BIOLOGY OF PLANTS.

3. Carbonic acid contains sixteen parts in twenty-two of
oxygen, and is a further source of this substance.

4. Gcinc or humus contains oxygen, which in the processes
of vegetation, is brought into contact with the vegetable or-
gans, and may thus be the source of a portion of the oxygen
which plants contain.

5. Nitric acid may be still another source, and perhaps
several other acids, as the carbonic, phosphoric and sulphu-
ric, which are known to exist in all soils.

IV. Theory of the A ssimilation of Oxygen and of Hydro-
gen. Woody fibre, which is the solid part of plants, and is
the most abundant of the products of vegetables, is composed
of carbon, with oxygen and hydrogen in the proportions to
form water ; that is, if the hydrogen and oxygen were to com-
bine, water would be formed and carbon left in a free state ;
or the composition may be represented by the elements of
carbonic acid, with a certain quantity of hydrogen.

Now the wood may be formed by the decomposition of
carbonic acid ; the carbon uniting with the elements of water,
and the oxygen escaping as effete matter ; or, what is more
probable, the carbonic acid may combine with the hydrogen
of the decomposed water, while the oxygen of the water
escapes. In either case, the quantity of oxygen separated
would be exactly the same.

But there are other compounds (as the acids), in which oxy-
gen is in excess ; in the process of their formation, therefore,
less oxygen would be separated. In case oxygen is in less
quantity than in the relative proportion to form water, as it
is in alkalies and neutral substances, such as starch, sugar,
wax and all resinous bodies, then, in the processes of assimi-
lation, much more oxygen would be separated. Such sub-
stances yield a larger quantity, or all of the oxygen, both of
the carbonic acid and of the water.* If this is a true rep-

* The following table of Liebig, illustrates still further the changes

THEORY OF ASSIMILATION. 157

resentation of the changes which actually take place in the
assimilation of oxygen and hydrogen, it proves conclusively
that the vital power is capable of reversing chemical laws.
For this process differs entirely from ordinary chemical com-
binations ; thus, for example, when carbonic acid, zinc and
water are mingled, hydrogen is separated ; but in the process
of vegetation, oxygen is separated from the living plant, and
given back to the atmosphere.

In the process of decay, oxygen is returned to the atmos-
phere in the form of carbonic acid, and is absorbed from the
air to form water ; hence, the process of nutrition and decay
are exactly opposite.

This theory serves rather to illustrate the nature of the
changes, than to point out the exact changes which take
place. In a similar way, it might be shown what changes
may take place, when other substances containing oxygen and
hydrogen are taken into the vegetable organs. It is there-
effected in assimilation, on the supposition that the carbon is derived
from carbonic acid, and the oxygen and hydrogen from the water.

36 eq. carbonic acid and 36 eq. hydrogen derived > c-

from 36 eq. vi^ater 5

with the separation of 72 eq. oxygen.
36 eq. carbonic acid and 30 eq. hydrogen de- ) o^ ?

rived from 30 eq. water \^ = Starch,

with the separation of 72 eq. oxygen.
36 eq. carbonic acid and 16 eq. hydrogen de- > ^ ,, -j

rived from 16 eq. water \^= Tannic Acid,

with the separation of 64 eq. oxygen.
36 eq. carbonic acid and 18 eq. hydrogen de- ) ^ . • ^ • »
rived from 18 eq. water \^= Tartaric Acid,

with the separation of 45 eq. oxygen.
36 eq. carbonic acid and 18 eq. hydrogen de- > ,, ,. ^ .,
rived from 18 eq. water ^ = Malic Acid,

with the separation of 54 eq. oxygen.
36 eq. carbonic acid and 24 eq. hydrogen de- > r^i j-^r

rived from 24 eq. water }^ = Od of Turpentine.

with the separation of 84 eq. oxygen.

158 BIOLOGY OF PLANTS.

fore highly probable, that plants derive their oxygen and hy-
drogen, as well as their carbon, from several sources ; and
that these two substances enter the vegetable organs in the
form of water ; of geine or humic, crenic and apocrenic
acids ; of ammonia ; of common air ; and, probably, of sev-
eral acids.

V. Source and Assimilation of the Nitrogen of Plants, It
was formerly supposed, that nitrogen existed in only a few
plants, but it is now established that it exists in all. " It
exists in every part of the vegetable structure."* The quan-
tity, however, is very small, compared with the other ingre-
dients of the vegetable principles. Hay, dried at 240° F.,
contains but IJ, oats 2j, and potatoes 1^ per cent. In the
ordinary state in which these substances are found, they must
contain a much less quantity.

This quantity is small only in comparison with the other
organic constituents, for if we calculate the quantity of nitro-
gen in an average crop of hay and grain grown on three hun
dred acres of land, it will amount to eight tons.t

This relatively small, but absolutely large quantity of ni-
trogen is of the highest importance to vegetation. In fact
the value of manure has been estimated by its power of yield-
ing nitrogen in the form of ammonia.| The body which ex-
ists in the smallest quantity in the vegetable products, is just
as necessary to their formation, as that which is most abun-
dant. It has been due to a neglect of this principle that so
little effort has, as yet, been made to supply plants directly
with this substance. Whence, then, do plants derive their ni-
trogen 1 The following are the principal sources.

* Liebig.

t A ton of hay contains about 30 lbs. of nitrogen ; but tlic quantity
depends very much upon the kind of crop. Red clover contains
double the quantity of nitrogen which common hay does ; hence, an
acre yielding three tons would require 180 lbs. of nitrogen.

X Dana,

SOURCES OF NITROGEN. 159

1. The atmosphere contains seventy-nine parts of nitro-
gen in one hundred, and as it is thus brought into direct con-
tact with the organs of plants, either as a gas, or dissolved in
water, it must be absorbed. Hence some have supposed it
possible, that a part of that found in vegetable bodies is de-
rived from that source.* But the nitrogen of the air possesses
such inert and indifferent properties, as to render it nearly cer-
tain, that it is not assimilated directly ; although we cannot
say what the vital power may effect. It is probable, however,
that nitrogen enters plants in some of its combinations. The
question whether it came originally from the atmosphere, is
quite different from the one now under consideration — the
immediate source of it.

2. Ammonia, as we have seen p. 81, is produced in consid-
erable abundance. It must be brought into contact with the
leaves and roots of plants, and enter into their organs. It is
composed of fourteen parts of nitrogen and three of hydrogen.
That plants derive a part of their nitrogen from it, appears
exceedingly probable from the following considerations.

(1) Ammonia is found in the sap of trees, and in the juices
of all vegetables. *' The products of the distillation of flowers,
herbs and roots, with water, and all extracts of plants made
for medicinal purposes, contain ammonia. Ammonia exists
in every part of plants, in the roots (as in beet-root), in the
stem of the maple-tree, and in all blossoms and fruit in an
unripe condition."! In these cases ammonia may possibly
be formed by the living power, or it may be the effete matter
arising from transformations ; but that such is the fact is ex-
tremely doubtful.

(2) That ammonia yields nitrogen to plants, is highly pro-
bable from the action of animal manures. Gluten is a sub-
stance containing the largest quantity of nitrogen in wheat, rye
and barley, and is found in different proportions. The more ani-
mal manure there is employed in the cultivation of these grains,

* Johnson. t Liebig.

160 BIOLOGY OP PLANTS.

the greater is the proportion of gluten which they contain. Now
animal manures derive their special efficacy from the ammonia
they produce ; and it is found, that the proportion of gluten
depends upon the capacity of the manure to form it. Thus,
putrid urine and human excrements will produce much more
ammonia than cow-dung or vegetable matter ; and hence
their peculiar efficacy. The guano, which forms a stratum of
sixty or eighty feet in thickness in the South Sea Islands, and
which is composed of the excrements of sea fowls, owes its
fertile properties, in part, to the large quantity of ammonia
which it contains. This manure is an article of commerce,
and is placed on the barren soils of Peru, where it produces
the most surprising effects. It is composed mostly of urate,
phosphate, oxalate and carbonate of ammonia, with a few
earthy salts.

Human urine contains nitrogen, in the phosphates and in
the urea; the latter, by putrefaction, is converted into car-
bonate of ammonia. Now it is well established, that human
urine is the most powerful manure for those vegetables vv hich
contain a large quantity of nitrogen. The urine of herbi-
ferous animals contains hippuric acid, a substance which is
easily decomposed into benzoic acid and ammonia.

(3) The powerful influence of the salts of ammonia, is part-
ly accounted for on the supposition, that they yield nitrogen
to plants. The kind of influence they exert gives force to
this position ; for the carbonate and sulphate of ammonia in-
crease the quantity of vegetable products, which require the
largest quantity of nitrogen; that is, the gluten and vegetable
albumen.

Ammonia, in cool countries, is the last product of the pu-
trefaction of animal bodies. A generation of a thousand mil-
lions of men are renewed every thirty years, and thousands of
animals cease to live, and are produced in a much shorter
period, whence the nitrogen they contained during life ? All
animal bodies yield ammonia to the atmosphere, hence it must

SOURCE OF NITROGEN. 161

always exist in rain and snow water. It is the simplest of
the compounds of nitrogen. Nitrogen has for hydrogen the
most powerful affinity. It is capable of being held in solu-
tion in water, and readily enters into combination with car-
bonic, sulphuric and muriatic acids, and by all these means it
becomes fixed in the soil. A certain portion of the ammonia
which falls in rain water evaporates, but some of it must en-
ter the organs of plants, and by entering into new combina-
tions in the different organs, produces albumen, gluten, qui-
nine, morphia, cyanogen, and a number of other compounds
containing nitrogen.

(5) Finally, if we add to these considerations the fact, that
ammonia is found in the atmosphere, that it is constantly
produced in the soil, and must enter the organs of plants,
where, owing to its easy decomposition, its nitrogen must be
assimilated, it becomes certain that it yields nitrogen in
the processes of nutrition.

The quantity of nitrogen which plants derive from this
source cannot be determined. Liebig attempts to prove, that
ammonia is the only source of the nitrogen. He also attempts
to explain the utility of gypsum, burned clay, powdered char-
coal and humus, on the principle that these substances absorb
ammonia from the atmosphere, and fix it in the soil. The
carbonate of ammonia, which is diffused through the soil and
dissolved in water, is decomposed by the gypsum,* and the
resulting sulphate of ammonia yields its nitrogen to the plant
as its wants demand. As water is necessary to the decom-
position of the carbonate by the gypsum, its influence is not
observed on dry fields. The other substances mentioned,
act by absorption, condensing the ammonia in their pores.
The arguments brought in favor of this theory, are not all
of them well founded ; and if they were, would not prove it

* One bushel of plaster, on this theory, would fix a quantity of am-
monia, equal to 6*250 pounds of horse urine, and every pound of ni-
trogen would produce 100 pounds of hay or grain,
14

162 BIOLOGY OF PLANTS.

true. Thus, for example, it is asserted, that the quantity of
nitrogen removed from a well conducted farm, in the form of
cattle and grain, must be greater than that returned in the
excrements. But Dana has shown, by direct experiment,
that the quantity of nitrogen in the excrements of animals, is
nearly double* that found in the food, and hence the quanti-
ty returned to the soil is constantly increasing.

The fact that ammonia is found in the atmosphere, that it
results from the putrefaction of animal bodies, and that it is
found in the sap of trees, does not prove that plants derive
all their nitrogen from it.

But one of the strongest objections to this theory, is the fact,
that in warm climates, where vegetation is most flourishing,
the process of putrefaction in animal bodies, produces nitric
acid, instead of ammonia ; hence this latter substance will be
found in the least abundance, where the largest quantity is
needed, and where it is actually consumed, if this theory is true.
" No conclusion," says Liebig, '' can then have a better foun-
dation than this, that it is the ammonia of the atmosphere,
which funishes nitrogen to plants ;" and we may add, no con-
clusion is better established than this, that ammonia does not
furnish plants with the whole of th^ir nitrogen.

Whatever reasons there may be for rejecting the theory
which derives all the carbon, oxygen and hydrogen of plants
from carbonic acid and water, we have equally good reasons
for the belief, that ammonia does not furnish plants with all
the nitrogen which they contain.

" If it be true," says Daubeny, '' as Liebig has endeavored
to establish, that plants obtain everything, except their alka-
line and earthy constituents, from the atmosphere, what, it
may be asked, becomes of the theory that attributes the wifit-
ncss of a soil for yielding several successive crops of the
same plant, to the excretions given out by its roots ? For if

* Dana's Muck Manual, p 136.

SOURCE OF THE NITROGEN. 163

plants receive the whole of their volatizable ingredients from
the atmosphere, these excrementitious matters, being com-
posed chiefly of carbon, hydrogen and oxygen, will not be
absorbed, and therefore cannot affect the succeeding crop.^"*

If the theory is true, which derives all the organic constitu-
ents from carbonic acid, ammonia and water, a plant ought
to grow in a purely earthy soil, when supplied with ammonia.
But no instance has been produced, and it is yet doubtful,
whether the experiment would succeed if tried.

The forms in which ammonia enters the organs of pi ants,
are probably various. It may enter uncombined, simply dis-
solved in water, and be assimilated in a manner similar to oxy-
gen, carbon and hydrogen, p. 156. But it probably enters as a
salt, that is, in combination with acids. Dr. C. T. Jackson
supposes, that " the carbonate of ammonia acts upon the or-
ganic matters of the soil, and renders the organic acids neu-
tral and soluble ; decomposes and renders inert, noxious,
metallic salts and other compounds." Dr. Dana supposes,
that ammonia combines with the geine to form a soluble
compound, and also acts by its presence to convert vegetable
matters into geine. In either case, it would be introduced
into the organs of plants, and its nitrogen assimilated.

It has been supposed by some, that the powerful influence
of ammonia was due to its stimulating properties, but others
have doubted such influence; among the latter is Liebig,
and among the former, Berzelius. The influence of light,
heat and electricity would lead to the opinion, that the vital
power of plants is capable of being excited, in a manner
analogous to that of animals.

If plants do not derive all their nitrogen from ammonia,
what other sources are there from which it can be derived ?
We have already observed, that the decomposition of vegeta-
ble matters forms,

3. Geine or humus, which may be a further source of nitro-
gen. Humus consists of humic, crenic and apocrenic acids.

164 BIOLOGY OF PLANTS.

Humic acid is composed of hydrogen, oxygen and carbon.
Crenic acid is composed, according to Hermann, of forty-
two parts by weight of carbon, sixteen of hydrogen, four-
teen of nitrogen, forty-eight of oxygen. Apocrenic acid is
composed of eighty-four parts of carbon, fourteen of hydro-
gen, forty-two of nitrogen, and twenty-four of oxygen. These
latter acids are soluble in water, even when combined with
bases, and contain a quantity of nitrogen, which must enter
the organs of plants. We have then, only to suppose similar
organic transformations, in order that their nitrogen may be
assimilated to the vegetable organs. As a part of the carbon
is derived from the soil, so a part, at least, of the nitrogen
may be derived from the same source.

The influence of crenate of lime (which is sometimes
found in the sub-soil) upon clover, favors the idea, that it
furnishes a quantity of the nitrogen to seeds, fruits, and other
parts of vegetables ; for it is found that clover contains nearly
double the quantity of nitrogen \vhich is found in many other
grasses.

4. Nitric acid. The putrefaction of animal bodies, yields
large quantities of nitric acid, especially by the fermentation
of manures. This acid combines with potash, soda and am-
monia, to form salts, which are found, more or less abundant,
in all fermented manures. The salts are soluble in water, and
must enter the vegetable organs. The acid is composed of
fourteen parts of nitrogen and forty of oxygen. Here, then,
is another source of the nitrogen of plants. That plants de-
rive a part, at least, of their nitrogen from this source, is
proved by the most incontestable facts.

Daubeny has shown, that nitrate of soda, placed upon lands
sown with wheat, increased the gluten of the wheat 4.25 per
cent., and the albumcnl 0.75 per cent. The gluten and
albumen contain great quantities of nitrogen, and will be
abundant in the seed, in proportion to the proper sup})ly of
matters from which they may obtain it. Whence did they

SOURCE OF THE NITROGEN. 165

obtain this additional supply of nitrogen, but from the nitric
acid 1 Nitrate of potash produced a similar effect. It is
well known what a powerful effect salts of nitric acid, espe-
cially salt-petre or nitre, have upon the growth of vegetables.
This influence must be due to the nitrogen which is fur-
nished to the gluten, vegetable albumen, and other products
of the vital power.

Upon the whole, then, it is highly probable, that plants de-
rive their nitrogen from ammonia, crenic, apocrenic and ni-
tric acids, and that vegetation will be abundant in proportion
as these substances are supplied to the roots of plants. They
are not, however, introduced in their pure state, but are com-
bined with inorganic bases, in the form of salts, and are de-
composed, and their elements assimilated by chemical and
vital forces.*

But whatever theories we may form on this subject, upon
the source and assimilation of the carbon, hydrogen, oxygen
and nitrogen of plants, one thing is certain, that the farmer
must supply vegetable and animal manures which contain
these elements, or the carbonic acid, water and ammonia of
the atmosphere, will not be gathered into the form of vegeta-
ble productions. The necessity of supplying the soil with
manure, cannot be set aside, by any theories of the source
from which plants derive their support ; and the best theory
is that which shall best explain the facts, and point out the
most direct and efficient means for increasing the quantity
and quality of the productions of the farm. And we believe
it will be found in the end, that plants derive their carbon, hy-
drogen, oxygen and nitrogen from the several sources named,
and that they are endowed with the power of adapting them-
selves to circumstances, so as to select a greater or less quan-
tity from each source ; but that one alone will not support

* Since writing the above, I have received two works, Johnson's
Lectures, and Dana's Muck Manual, which substantiate the views
given in the text.

14*

166 BIOLOGY OF PLANTS.

their organs in a vigorous state of growth, and enable them
to attain their highest perfection.

Sect. 4. Definitions. — Source and Assimilation of the inor-
ganic Constituents of Plants.

Potash or potassa (KO=47.15) is composed of the metal po-
tassium and oxygen, one equivalent of each ; of course its com-
bining immber is 8-f-39=47. This substance is well known.
It is found in all plants. It is a solid, easily soluble in water,
caustic to the taste, eminently alkaline in all it properties and
relations.

Carbonates of potassa are known to us under the name of pot
and pearl-ashes, and saleratiis. The nitrate of potassa is known
as nitre and salt-petre. All the salts of this alkali are useful
substances.

Soda (NaO.31.3) is an alkali similar to potassa. It is com-
posed of 8 parts of oxygen, and 23.3 of the metal sodium ; hence
its equivalent is 31.3 and its symbol is NaO. It is a white or
gray solid, very soluble in water, caustic to the taste, and, com-
bined with acids, forms a large class of salts.

The nitrate of soda, called cubic nitre, is similar in its chemical
properties to nitrate of potassa. The carbonate of soda is well
known, as the substance used for soda powders. The sulphate
of soda is the well known substance Glauber'' s salts.

Common salt is a chloride of sodium, but when it is dissolved
in water, or when the chlorine is removed, the metal sodium
immediately combines with oxygen, if water is present, and
forms soda. The chlorine unites with the hydrogen of the wa-
ter, and forms muriatic acid; these may then combine, and form
hydrochlorate of soda.

Magnesia (MgO.20.7) is a white powder, of an earthy appear-
ance, known in the shops as calcined magnesia. It is comi)osed
of a peculiar metal, magnesium, 12.7 parts by weight, and 8
parts of oxygen. Its symbol is MgO. It is very infusible and
slightly soluble in water, rc({uiring 5142 times its weight of wa-
ter, at ()0° F., and 36,000 of boiling water to dissolve it. AVhen
exposed to the air, it absorbs carbonic acid and is converted into
tlw carbonate of magnesia, also a white powder, very insoluble
in water. Phosphate of magnesia is a comi)ound of phosphoric
acid and magnesia, and has not been fully examined. Sul-
phate of magnesia is the common Epsom salts.

DEFINITIONS AND DESCRIPTIONS. 167

Lime is composed of the white metal, calcium 20.5 parts,
and 8 parts of oxygen. It is a protoxide of calcium, and is
thus represented, CaO.=28.5. Lime is a grayish white
solid, caustic, acrid and alkaline to the taste. It has a strong
affinity for water, with whicli it combines, attended with the
evolution of much light and heat, and forms a bulky hydrate,
called slacked lime. It has a strong affinity also for several acids,
with which it combines. The carbonate oj lime is the common
limestone and marble. Sulphate of lime is gypsum, or plaster
of Paris. Phosphate of lime is the substance which forms the
bones of animals, and exists in the mineral apatite.

Alumina is composed of 27.4 parts of aluminium, and
24 parts of oxygen. Its composition is thus represented.
Al'^03 51.4. It is an inodorous, tasteless substance, insoluble in
water, possessing the properties, both of an acid, and of an alkali.
When moistened, it forms a ductile mass, and, when combined
with silicic acid, forms clay. It is the base of all kinds of pot-
tery.

Oxides of iron. There are at least two oxides of iron. The
protoxide is composed of twenty-eight parts of iron and eight of
oxygen, and is represented by FeO=36. It has a dark blue
color, and is magnetic. It is so combustible as to take fire,
sometimes, in the open air, by which it becomes converted in-
to the

Peroxide of iron which may be represented by Fe'^O^^BO.
This is the red hemetite of mineralogists. It is a brownish-
red substance, easily thrown down from a solution of its salts,
by ])ure alkalies. Both of the oxides combine with several
acids, and form a numerous class of salts. The sulphate
of the protoxide is known as copperas. The carbonate of the
X)rotoxide exists in most chalybeate mineral waters.

Oxides of manganese. There are several oxides of manga-
nese. The principal one is the

Peroxide of manganese, which is composed of 27.7 parts of
manganese (Mn) and 16 parts of oxygen. The symbol is
jMn02=43.7. This oxide occurs in black earthy masses, and
is not affected by ex|)osure to the air or water. It combines
with several acids and forms salts.

Silicic acid is composed of 22.5 parts of silicon and 24 parts
of oxygen (Si03=46.5). It is best known in the form of sand,
rock-crystal, quartz and flint. It is a tasteless, very infusible
and insoluble substance; and although it is not acid by the or-
dinary chemical tests, it is the most powerful of acids, forming

168 BIOLOGY OF PLANTS.

a large class of salts. It is usual, however, to call the com-
pounds of silicic acid with'bases, silicates, and the compounds of
other acids with the same bases, salts.

Hydrochloric acid is composed of one equivalent of chlorine,
35.42, and one of hydrogen, 1=36.42. (HCl.) This acid, in
its pure state, has very acrid and caustic properties. It is com-
, monly called muriatic acid, because obtained from sea salt. Its
^^i>>y"U)Jsprinciple^• salt is hydrochlorate of anmionia, known as sal am-
moniac.

Sulphuric acid, a compound of sixteen parts of sulphur and
forty of oxygen, is an oily liquid well known as oil of vitriol.

Phosphoric acid is composed of two equivalents of pliospho-
rus, 31.4, and 5 of oxygen, 40=71.4 (symbol P^QS). This
acid resembles snow or ice. It is intensely sour, and com-
bines with a number of alkalies and alkaline earths, forming a
class of salts called phosphates. Phosphate of lime is the prin-
cipal substance in the bones of animals.
. JVitjic acid has been described, p. 48.

Is morphisnf IS a term used to designate the fact, that bodies of
very different chemical constitution, may assume the same crys-
talline form, and may displace each other in any compound.
When this is the case, that is, when one body is substituted, for
another, there is not an equal, but an equivalent proportion ;
thus, when soda is substituted for potassa, thirty-one parts of
the former take the place of forty-seven of the latter.

As plants uniformly contain several inorganic bodies, we
infer, that these substances are necessary for the formation of*
particular organs. For although the inorganic constituents
of plants may vary according to the soil in which the plant
grows, a certain number of them is absolutely essential to its
development. The principal of these inorganic substances
are potash, soda, magnesia, lime, alumina, and oxides of iron
and of manganese, which are the inorganic bases, and are
generally combined with silicic, hydrochloric, sulphuric, phos-
phoric, carbonic and nitric acids.

The inorganic bases of plants vary with the nature of the
soil. DeSaussure and Berthier found magnesia in the ashes
of a pine tree, growing at Mont Breven, but none in the ashes

INORGANIC CONSTITUENTS OF PLANTS. 169

of the same species of tree from Mont La Salle. The potash
and lime also varied in the two localities. This is accounted
for by the fact, that one inorganic base may be substituted
for another, in an isomorplwus proportion. If, therefore,
there is not in a soil that inorganic base which the plant most
likes, it will take up a quantity of some other base. There
is, however, some inorganic base, which a species of plants
prefers to any other, and if that is entirely absent, in some
cases the plant will be imperfect or fail to grow altogether,
while in others it will be diminished in some of its pro-
ducts. As these bases are combined with inorganic, and al-
so with organic acids, and as it is only with the latter that
substitutions can be made, when one base is substituted for
another, a different quantity will be employed, because one
equivalent of base must be substituted to saturate the acid,
and the combining ratios differ in different bases. But still
there is a remarkable law in reference to the quantity o^inetal-
lic oxides or inorganic bases in all these substitutions, the
quantity of oxygen is exactly the same ; that is, there is an
equal number of equivalents of metallic oxides, whatever sub-
stitution may be made. Hence, if the soil does not contain
one kind of base, it is not on that account barren, but an-
other may supply its place. But notwithstanding this fact,
some bases exert a better injluence upon the development
of plants than others. For example, phosphate of magnesia,
in combination with ammonia, is found invariably in the seeds
of all kinds of grasses. It is contained in the outer, horny
husk, and is introduced into the bread with the flour, although
the bran contains the larger quantity of it. Hence, this
substance is necessary to the perfect development of the
grasses and grains. It would also be next to impossible to
raise wheat without potash.

There are, moreover, certain species of plants, which re-
quire certain alkalies for their growth ; such as the sea-plants.

170 BIOLOGY OF PLANTS.

which require soda, iodine, or some substance yielded by the
sea, as common salt. Such plants will follow the salt water,
wherever it is found. If salt-works are opened in the inte-
rior of a country, the sea-weeds will find the spot, and mi-
grate to it.

The absolute necessity of inorganic bases to the perfect
development of plants, is shown by the fact, that each species
of plant produces organic acids, as the acetic, tartaric, ma-
lic, etc. These acids are united with bases, either organic or
inorganic, and the latter is the case, in most instances. The
quantity of these acids can be accurately ascertained in each
species of plant; and as their power of saturation is known,
the quantity of inorganic bases may be accurately deduced.
It must always bear an exact ratio to the organic acids. The
quantity of these acids varies according to the nature of the
soil, in order to suit the different organic bases.

As the roots of plants, like a sponge, imbibe from the
soil whatever substances* are held in solution by water,
it is evident, that many of the inorganic bases and other mat-
ters will be introduced into the organs of the plants, which
cannot be assimilated. These substances are again returned
to the soil. This process has been inferred from observation.
From the nature of the case, we have a strong presumption
in favor of its truth. It may, at least, explain very many
phenomena of vegetation. Macaire Princep has shown by
experiment, that plants made to vegetate with their roots in
a weak solution of acetate of lead (sugar of lead), and then
in rain-water, yield back all the lead absorbed. So, also,
when a plant is sprinkled with nitrate of strontia, it will ab-
sorb it by the leaves, but return it all to. the soil ; hence, we
may color a plant with various substances;! but, after a

* The roots do appear to possess some power of discriRiination, as

they will imbibe different quantities of substances which are presented.

t " When the soil, in which a white liyacinth is growing in a state

INORGANIC CONSTITUENTS OF PLANTS. 171

while, the coloring-matter will all be returned to the soil.
When, therefore, a plant has not a sufficient quantity of its
appropriate alkali, it will take up some other, but may return
it to the soil, when that alkali is supplied ; hence, the impor-
tance of supplying the appropriate alkalies and alkaline earths,
for the perfect development of every species of plants.

The source of the inorganic constituents of plants, is a
point much more easy to determine, than the particular form
and mode of their introduction into the organs of plants, and
of their assimilation.

1. Pgtassa. Whence do plants derive their potash?
This question is easily answered. The rocks contain large
quantities of potash, locked up in the feldspar. Granite rocks,
such as exist abundantly in New England, contain about
seven per cent, of potash, in the form of a silicate, that is,
united with silicic acid. This potash is eliminated by the
action of the air, and by carbonic acid ; but growing plants
possess the power of decomposing the rocks, and of obtaining
it in much larger quantities. This is proved by the fact, that
plants growing in a glass vessel, will decompose the glass, to
obtain the potash which enters into its composition.

The quantity of potash in a soil, is sufficient to sustain
most plants for an indefinite period of time. We might al-
most say, that it is inexhaustible ; for pine plain soil
of six inches in depth, contains, per acre, thirty-six tons of
potash, and a ton and a half of lime. Some plants, however,
such as wheat and tobacco, by being planted upon the same
soil for a series of years, will exhaust the potash to such an
extent, that a change of crops must be resorted to, to restore
fertility. There may be some cases, in which minerals be-

of blossom, is sprinkled with the juice of the Phytolaca decandra
(American nightshade), the white blossoms assume, in one or two
hours, a red color, which again disappears after a few days under the
influence of sunshine, and they become vv^hite and colorless as be-
fore,"— L.

172 BIOLOGY OF PLANTS.

come wholly decomposed ; and, when that is the case, the soil
becomes absolutely barren, and nothing can restore fertility
but the addition of alkalies and gravel ; hence the necessity
and utility of a rotation of crops ; for when all the potash has
been removed from the soil by one family of plants, other
plants may be substituted, which do not require this alkali for
their growth.

In other cases, jTree alkali is needed. Hence the effect of
ploughing in green crops, and the utility of fallows. The
growing plant eliminates the potash from the feldspar,* and
it is then turned into the soil and is ready to be applied to
future crops.

All kinds of grain contain, in the outer part of their leaves
and stalks, a large quantity of^ s'lViCRte of potash, which must
be derived from the soil. If now we increase the amount of
grass or grain by means of gypsum, a larger quantity of potash
will be eliminated, and the free alkali will be carried off, so
that in a short time, the crop will be diminished, and either
a fallow or some other means must be resorted to, to restore
that alkali.

The planters of Virginia, according to Liebig, exhausted
their soils by cultivating for a century in succession, tobacco
and wheat on the same land without manure. By this pro-
cess, twelve hundred pounds of alkalies were in the course
of one hundred years, abstracted from every acre of soil.
Thus these lands were nearly deprived of alkali, and are
now barren wastes. Hence the necessity of returning the

* There is not much danger that the alkali will be exhausted by
this process. The quantity contained in the rocks, is almost inex-
haustible, compared with that taken up by plants ; for it is found,
that the wheat straw, grown on an acre, takes up only twenty-two
pounds of potash, and the quantity in the soil would be sufficient for
the straw, during a period of three thousand years. The quantity of
potash on ap acre of granitic rock six inches in depth varies from
ninety to one hundred and twenty tons, but a fsir less quantity is
found in the same depth of soil.

SOURCE OF SODA. 173

potash to the soil, in the vegetable, animal and saline ma-
nures. If no vegetable and animal matters are added, a
constant course of cropping will extract the free alkalies,
and however rich the soil may be in humus, plants will not
flourish.

The form in which potash enters the organs of plants,
and the mode of assimilation, is a matter of theory. It ex-
ists in the form of a silicate, in ashes, in feldspar and in
manures. It is possible that it is dissolved in water and thus
conveyed to the roots of plants. It is also found in com-
bination with organic acids. If it were introduced then, in
the form of an oxide dissolved in water, it would combine
with the organic acids in the plant, and form the vegetable
compounds in which it is found. It may be introduced in
combination with humic, crenic and apocrenic acids. But
the most probable theory is, that potash is combined with
nitric, or some of the inorganic acids, and introduced as a
salt ; that it is decomposed by the organic acids in the plant,
and the acid, either sent out to act upon the silicates and
obtain more alkali, or decomposed and its elements assimi-
lated.

2. Soda. The source and the assimilation of soda is sim-
ilar to that of potash. The rocks which supply soda to
plants are very few. It is obtained from the sea or salt wa-
ter; hence, plants containing this alkali in the greatest
abundance, are found near the sea or salt springs. Com-
mon salt is a chloride of sodium, and forms soda in the form
ofhydrochlorate of soda by the decomposition of the salt and
the water. Now a small quantity of salt is evaporated from
salt water,* is carried inland, and becomes one source of
the soda of plants ; hence the useful effects of salt upon some
soils, and for particular crops.

3. Magnesia. Magnesia is also derived from the rocks,

* Liebig, p. 192.

15

174 BIOLOGY OF PLANTS.

and is much more abundant than soda.* It is contained in
feldspar and mica, two ingredients of all granitic soils, also
in hornblende, but especially in serpentine. The latter
rock contains from forty to forty- four per cent. Hence it
is an ingredient of all soils, and is either eliminated by the
growing plants, or by the acids in the soil. The phosphate
of magnesia, as we have seen, is an invariable constituent in
all kinds of grass. This alkali may, however, be extracted
from the soil, and must be returned by animal and vegetable
manures.

Theory of assimilation. Magnesia may enter the organs
of the plant, as a phosphate. But that plants should assim-
ilate bodies just as they are receivpd into their organs, is
contrary to the general doctrine. It unites with several
acids and is probably introduced in several forms. In the
transformations which take place, the phosphoric acid may
be formed, and combine with the magnesia in the act of as-
similation.

4. Lime. Lime is found in the ashes of most plants, and
is derived from the granitic rocks, and from the carbonate
and sulphate of lime, two very abundant substances in na-
ture. The quantity contained in the soils of New England
is very small, being less than three per cent. Hence, lime is
added to most soils with the highest benefit, either as pi aster j
marl or air-slacked lime, which latter has become partly car-
bonated.

Theory of assimilation. The mode by which this is in-
troduced into the organs of plants, is probably in the form of
geate, or crenatc and humatc of lime,f a substance always
found in the humus of soils.

* Granitic rocks contain from one to three per cent. } an acre six
inches deep would yield from ten to eighty tons.

t If too much lime is added, it may form a super-salt, iess soluble
an the other, and hence the liability of injuring a soil by its appli-
cation. A small quantity only is required for the growth of plants.

SOURCE OF SILICA. 175

Some plants contain sulphate of lime or gypsum, as
clover, while in others, the lime is found as a tartrate or
malate, that is, in combination with organic acids, which lat-
ter must have been formed before the lime could be assimi-
lated.

Phosphate of lime is a powerful manure, and may, in
small quantities, enter the organs of plants. But in this
case, as in that of potash, the great point is to furnish it in
any form.

5. Alumina is sometimes found in plants, but in very
small quantities. It may enter in combination with phos-
phoric acid, or with crenic and apocrenic acids.

6. Silica or silicic acid. The epidermis, or outer bark
of trees, the vessels in which the sap circulates, and the sur-
face of the grains and grasses, are composed in part of this
acid. As it is not soluble in water, nor in cold alkalies, the
most common solvents in the soil, it has been a point of
some difficulty, to determine the form in which it can be in-
troduced.

It is supposed by some, that it is combined with crenic
acid, a compound which is found in river water, and in the
soil. This substance must enter the roots of plants with
water, and may then be assimilated.

It is possible, however, that the silica, found in plants, is
introduced by means of galvanic action, or the catalytic force
of life.

There is still another mode of introducing this substance.
It forms soluble salts with alkali, as potash, and when first
liberated from its combinations, according to a well known
law, the silica becomes soluble, and capable of entering the
organs of plants.

7. The metallic oxides of iron and manganese are found
in some plants, and are derived from the soil. Iron is the

One grain of lime, in a hundred of the soil, will produce fertility,
Avhere all v/as barren before.

176 BIOLOGY OF PLANTS.

most widely diffused substance in nature, nearly all rocks
containing traces of it. Iron is found in many seeds.

Manganese is nearly as widely disseminated, but is found
in still less quantities, both in the soil and in the organs of
plants.

8. Phosphoric acid has been found in all plants hitherto
examined, and always in combination with alkalies and alka-
line earths. The seeds of different grains form a large quan-
tity of phosphate of magnesia. This acid is derived from
the soil, and is an ingredient in all lands capable of cultiva-
tion. Phosphoric acid has also been detected in all mineral
waters. Sulphuret of lead (galena) contains crystallized
phosphate of lead. Phosphate of alumina often encrusts rock
crystals. Phosphate of lime is found in many rocks, and
even in volcanic holders. There can be no doubt but that
this acid is developed in the soil, and supplies phosphate of
lime to plants, and plants furnish it to the bones and brains
of animals.

9. Sulphuric, nitric and carbonic acids, combined with
potash and other alkalies, and common salt, or chloride of
sodium, are found in some plants.

Nitrate of potash is formed during the fermentation of ma-
nures. Sulphuric acid is formed from the sulphuret of iron
which is found in most rocks.

Common salt, (chloride of sodium,) must come from the
sea, or from animal manures, as it could not be retained in
the soil, owing to its solubility. Very small quantities of ox-
ide of copper, and some metallic fluorides are absorbed by
some plants, although we cannot afhrm, that they are ne-
cessary to their growth.

10. Some plants also take up small quantities of iodine
and bromine in the form of iodides and bromides ; but wheth-
er they are necessary to the growth, cannot be fully ascer-
tained, although it is probable they are, since such plants are
never found away from the sea, the source of these sub-

INORGANIC CONSTITUENTS. 177

Stances. Sea plants seem to be collectors of iodine and bro-
mine, just as land plants are of alkalies, such as potash, etc.

We do not know in what form all of these inorganic con-
stituents of plants enter the organs, nor the changes that
are wrought upon them in the process of assimilation ; but
we may derive from the doctrine of transformations already
described, the general nature of the process, and the best
idea we can obtain of nutrition and assimilation.

Thus it appears, that the inorganic constituents of plants
are as indispensable to their perfect development, as the car-
bon, oxygen, hydrogen and nitrogen. It is therefore of the
first necessity, that these substances should be supplied to
plants in their proper proportion. The facts developed in
this section, relative to the source of the constituents of
plants, illustrates the need there is of proper attention to the
soil, as it is from the soils that most of the ingredients, ne-
cessary to their perfect growth are derived.

Having now considered the general conditions requisite to
the life of veoretables, with the various changes which take
place in the phenomena of vegetation, we will here close the
subject of Biology ; not because we have exhausted it, but
because enough has been advanced, to give the reader a gen-
eral idea of the vegetable processes, and of the utility of sup-
plying the proper conditions, for the life and growth of those
vegetable substances, which are the support of the animal
kingdom. Any means, which shall increase these products,
are to be sought out with the most diligent care ; we have,
therefore, devoted a large portion of succeeding chapters to
the subject of the soils, as the most direct means of secur-
incr so desirable an end.

15*

GEOLOGY AND CHEMISTRY OF SOILS.

CHAPTER IV.

ROCKS AND THEIR RELATIONS TO VEGETATION.

Soil is formed by the decomposition and wearing down of
ihe rocks, which are mingled with variable quantities of ani-
mal and vegetable matters. All soils consist of compound
bodies, and these compounds are generally formed, by the
union of two or three simple substances. In order, therefore,
to understand the nature of soil, and its relations to vegeta-
tion, it will be necessary to give a general view of the simple
and compound bodies, which enter into the composition of
the rocks, the manner in which they are combined, and the
process by which the rocks are converted into soil.

Sect. 1. Simple Bodies which enter into the Composition of
the Rocks.

The number of simple bodies known to chemists, is fifty-
five. Of these, only fourteen enter into the composition of
rocks and soils ; hence, these fourteen bodies constitute
nearly the whole matter of the globe. The remaining sub-
stances are found either in too small quantities to affect the
general mass, or exist only in particular locations of limited
extent.

The proportion in which these bodies exist in the rocks,
beginning with the most abundant, is nearly in the following

METALS. 179

order ; oxygen, silicon, calcium, aluminium, potassium, iron,
hydrogen, sodium, magnesium, manganese, carbon, sulphur,
phosphorus and nitrogen.

Some of these substances, with their combinations, have
been described in previous chapters. It is intended here, to
arrange them into their natural groups, and to give a general
description of those which have not yet been referred to.

I. Seven of these simple bodies already described, viz.
oxygen, hydrogen, carbon, nitrogen, sulphur, silicon and phos-
phorus, are non-metallic substances. With the exception of
oxygen and nitrogen, they are combustible, and with the excep-
tion of carbon, do not exist in the rocks in their pure state.

II. The remaining substances are Metals. These are di-
vided into three groups. 1. Potassium and sodium, which
are metallic bases of the alkalies potassa and soda. 2. Alu-
minium, calcium and magnesium, which are the metallic
bases of the alkaline earths alumina, lime and magnesia. 3.
Iron and manganese, which are the bases of metallic oxides.

Potassium is a white metal, lighter than water, and so soft,
that it easily yields to the pressure of the fingers. It is the
most combustible of the simple substances. This is owing
to its affinity for oxygen, which it will abstract from water
with such rapidity, as to burn upon its surface with a beauti-
ful purple flame. It thus decomposes the water, and forms
the alkali potassa, which is the basis of potash. It is widely
disseminated in the rocks, though not in very large quanti-
ties.

Sodium is also a white metal, like silver, lighter also than
water, but a little heavier than potassium, to which it is simi-
lar in texture and consistency. It is less combustible than
potassium, but will also rapidly decompose water to obtain
its oxygen, with which it forms the pure alkali soda, the ba-
sis of all the compounds of soda, known under the names of
common salt, glauber's salts, etc.

Magnesium is a pure white metal resembling silver, very

180 GEOLOGY AND CHEMISTRY OF SOILS.

malleable, and fusible at a red heat. It combines with oxy-
gen and forms magnesia, which possesses alkaline properties,
and is the basis of the common magnesia (the carbonate) and
epsom salts. It exists in serpentine rocks.

Aluminium is a grey powder, slightly cohesive. It gen-
erally exists in small scales or spangles of a metallic lustre.
When combined with oxygen, it forms alumina the basis of
all clays, and is a: constituent of most rocks, especially of the
primitive and tertiary formations.

Calcium is a white metal, and combines with oxygen and
forms lime, the basis of all lime rocks, shells, marble, chalk,
plaster of Paris, etc.

Iron is a well known metal, existing in all the primitive
rocks, in combination with oxygen and sulphur.

Manganese is a more rare metal, of a greyish-white color,
existing in primitive rocks in combination with oxygen, and
is called oxide of manganese, or peroxide of manganese.

Chlorine, iodine and hromine are found in sea-weeds ; jlu-
orine and lithium exist in some plants, but in small quantities.

Sect. 2. Compounds formed hy the fourteen simple Bodies.

I. Primary compounds, or bodies composed of two simple
substances.

The combinations of these fourteen simple substances,
above described, form three distinct classes of primary com-
pounds. 1. Acids. 2. Alkalies, or alkaline earths and me-
tallic oxides. 3. Urets.

1. Acids. Of this class, only five or six enter into the
composition of rocks; viz. silicic, carbonic, sulphuric, phos-
phoric, nitric and hydrochloric or muriatic acids. These
acids have been described pp. 48, 168. The silicic is most
abundant in the rocks, constituting about forty per cent, of
the crust of the globe. Carbonic acid ranks next in quan-
tity. Then follow the others, in the order above named.

ALKALIES, URETS, SALTS, SILICATES, 181

The most important property of acids is their constant de-
sire to unite with alkalies, alkaline earths and oxides; and
as they possess different degrees of affinity for bases, they
are in the soil constantly exchanging them.

2. Alkalies, alkaline earths and metallic oxides. The al-
kalies are potassa, soda and ammonia. The alkaline earths
are lime, magnesia and alumina. The oxides are oxides of
iron and of manganese. These with the exception of the
two last, do not exist in the rocks in their pure state, but their
agency in the soil is of the highest practical interest to the
farmer.

3. Urets. The urets are bi-elementary compounds, neither
acid nor alkaline. They are formed by the union of the non-
metallic combustibles with each other and with metals. The
principal are sulphuret of iron, (iron pyrites), phosphuret of
iron, carburet ofiron, phosphuret of lime, phosphuret of sili-
con, etc.

Their distinguishing property is, a readiness to change into
salts through the influence of atmospherical or other agents.

II. Secondary compounds or scdts. These are compounds
formed by the union of the primary compounds. The acids
combine with the alkalies, alkaline earths and oxides, which
are called, in reference to the acids, bases, and form ternary
or quaternary compounds.

Salts may be conveniently classed under their respective
acids.

1. Silicates. The silicates are those compounds or salts,
in which silicic acid combines with the bases above named.
Those entering into the composition of the rocks, are the
following : silicates of potassa, soda, lime, magnesia, alumina,
oxide ofiron and of manganese. Almost the entire mass of
rocks is composed of these silicates, and from seventy to
eighty per cent, of soils. These salts when neutral, are not
soluble in water, and therefore are not capable of being dis-
solved in that fluid, except in very minute quantities ; hence.

182 GEOLOGY AND CHEMISTRY OF SOILS.

they remain unaffected, unless substances are presented capa-
ble of decomposing them, and of forming soluble compounds.

2. Carbonates are a class of compounds formed by the
union of carbonic acid with the bases above mentioned. All,
excepting the carbonate of lime, or marble, are found in
small quantities in the rocks.

Carbonate of lime is very abundant, forming nearly ^ part
of the crust of the globe.

Carbonate of potassa is the common potash, pearlash, etc.
and is usually obtained from ashes.

Carbonate of soda is the well known substance used for
soda powders.

Carbonate of magnesia is a white powder used in medi-
cine,"under the name of" calcined magnesia."

Carbonate of iron is more widely diffused among the rocks,
but the quantity is small.

Carbonate of ammonia is a powerful stimulant to animal
and vegetable organs, and is found in the fermentation of ani-
mal manures, and exists, according to Liebig, in the atmos-
phere. It is, as we have seen, one of the substances from
which plants derive their nitrogen. All the carbonates are
easily decomposed, and have an important influence on vege-
tation, especially by means of their action upon the silicates
from which alkali is obtained for the use of the vegetable.

3. Sulphates. The sulphates are formed by the union of
sulphuric acid with potassa, alumina, soda, magnesia, am-
monia, lime, oxide of iron and of manganese. Most of the sul-
phates are well known substances. The sulphate of potassa
and alumina is known by the common name, alum. Sul-
phate of soda is glauber's salts; of magnesia, epsom salts ; of"
lime, plaster of Paris ; of oxide of iron, copperas, etc. The
most abundant sulphate is that of lime or plaster, which
forms extensive mountain ranges and is widely disseminated
among the rocks.

4. Nitrates. The nitrates are compounds of nitric acid

SIMPLE MINERALS. 183

with the bases above named. The nitrate of potassa is the
nitre or salt-petre of commerce. The other nitrates are rare-
ly found in the rocks. Nitrate of soda is next to nitre in
importance.

5. Phosphates. In these compounds, the acid is the phos-
phoric, and the most abundant sahs are the phosphates of lime,
found in most rocks ; phosphates of iron, soda, potassa, etc.

6. Muriates. The muriatic acid forms but few com-
pounds, which exists in any considerable quantities in the
rocks. Common salt, when dissolved in water, has been re-
garded as a muriate of soda. It is found in sea water, and
widely diffused in certain geological formations, (the new red
sandstone,) but most writers regard it as a chloride of sodium,
a compound of chlorine and sodium.

The compound bodies, Vv'hich have been enumerated, are,
with the exception of silicic acid and carbonate, sulphate
and phosphate of lime, rarely found in the rocks in a pure or
separate state. They are variously combined, and form the
natural substances, called the simple minerals ; and the sim-
ple minerals, united mechanically, and not chemically, form
the rocks.

In order to understand the character of the rocks and the
soil, it will be necessary to describe these compounds, as
they actually exist in nature.

Sect. 3. Simple Minerals which enter into the composition
of the Rocks.

Of the three or four hundred species of simple minerals,
only seven or eight form the great mass of the rocky strata of
the globe. These are quartz, mica, feldspar, hornblende,
talc, serpentine, calcareous spar, or limestone and pyrites.

1. Quartz is nearly pure silicic acid. It exists under a
a great variety of forms, and presents different appearances.
The purest variety is rock crystal, which is limpid and

184 GEOLOGY AND CHEMISTRY OF SOILS.

transparent. The impure varieties contain variable quanti-
ties of iron, alumina, manganese and nickel. These varie-
ties are found under the names of jasper, flint, chalcedony,
rose-quartz, horn-stone, chrysoprase, feruginous quartz, cor-
nelian, agate, amethyst, etc. The prevailing color is that of
water, or white. There are various shades of red, yellow,
green, blue and brown. It is so hard as to scratch glass, but
is not scratched in turn. Its lustre resembles glass, and may
be known by not being acted upon by any acid, excepting
the hydrofluoric.

2. Feldspar differs from quartz in having a paler white
color, and lamella or granula texture. It scratches glass, and
is scratched by glass in turn. It is a silicate of alumina, and
is composed of silica, 64 parts in 100, alumina 20, potash
10 to 14, and traces of lime, oxide of iron and water.

3. Mica. This mineral, known under the name of ising-
glass, exists in thin, shining scales, and in broad tables or plates.
It is of various colors. It is transparent, and the laminae
are thin, very flexible, elastic and very tough. These char-
acters sufl^ciently distinguish it in the rocks. It is a silicate^
and varies in composition. A specimen analyzed by Rose,
gave

0.^6
0.56
1.39

A specimen, analyzed by Turner, had 5.49 of lithia,
but no oxide of iron. Its composition may be stated gener-
ally

Silica

47..50

Oxide of manganese

Alumina

37.2

Fluoric acid

Potash

9.60

Water

Oxide of iron

3.20

Silica

48

Oxide of iron

lto2

Alumina

34

Oxide of manganese

1 to 2

Potash

8 to 9

It appears, therefore, to be a compound of the silicate of
alumina, potassa, oxide of iron and of manganese.

4. Talc resembles mica in its thin, shining scales, but
may be distinguished from it by its want of elasticity. It is

Silica

43.83

Magnesia

13.61

Lime

10.16

Alumina

7.47

SIMPLE MINERALS. 185

softer, yielding easily to the nail, and has a soapy feel. It
includes the varieties, chlorite (which is green), nacrite,
green earth, steatite or soapstone, and vermiculite.

It is composed of silica 62, magnesia 27, oxide of iron 3.5,
alumina 1.5, water 6. Nacrite and green earth have from 4
to 17 per cent, of potash, and a trace of lime. It appears to
be a silicate of magnesia, and of the other bases which are
above mentioned.

Hornblende is a black or brown mineral, exceedingly tough,
and. of an earthy appearance when not crystallized.

It is composed, according to the analysis of Bornsdorf, of

Protoxide of iron 18.75

Protoxide of manganese 1.15

Hydrofluoric acid 0.41

Water 0.50

Hence it is a silicate of magnesia, lime, oxide of iron, etc.

Serpentine. Serpentine is a hard compact mineral, of a
resinous or greasy lustre, and of a dark-green or blackish-
green color. According to the analysis of Shepherd, it is
composed of

Silica 40.08 I Water 15.67

Magnesia 41.40 I Protoxide of iron 2.70

A species from Lynnfield, Mass. analyzed by Dr. C. T. Jack-
son, gave silica 37, magnesia 42, oxide of iron 2, water 15.
Hence, serpentine is almost wholly a silicate of magnesia.

Calcareous spar, or carbonate of lime, is well known by the
names of marble, chalk, limestone, etc. It assumes a great
variety of forms, and may be known by the brisk efferves-
cence produced by dropping on to it a few drops of sulphuric
acid. It is composed, according to Phillips, of carbonic acid
44, lime 55.5. Limestone is found, in great abundance,
but it is not always pure. It often contains magnesia, the dolo-
mite species ; iron ; the feruginous limestone ; alumina ; and
silica. The limestones of Rhode Island, according to the
analysis of C. T. Jackson, contain from 50 to 97.6 per centi.
16

186 GEOLOGY AXD CHEMISTRY OF SOILS.

of carbonate of lime ; from 1 to 40 per cent, of insoluble mat-
ter, probably silicate of alumina ; in some cases, 4 per cent,
of oxide of iron, from 0. to 40 per cent, of magnesia. The
limestones of Massachusetts, according to Prof Hitchcock's
analysis, contain from 44.8 to 99.6 per cent, of carbonate of
lime ; from 0 to 40 of carbonate of magnesia in some species ;
from 0 to 8 per cent, of carbonate of iron ; and from 0.4 to
61.6 of silicate of alumina. The sulphate of lime or plaster,
with the phosphate, may also be included in this group, as in
some cases entering into the composition of the rocks.

Pyrites, or iron pyrites, is a bisulphuret of iron, and exists
extensively in primitive rocks, but in much less quantities
than the preceding minerals. It resembles gold, and is often
taken for that substance ; hence it has been called ybo/'s gold.

It will be seen that silex or silicic acid is the most abun-
dant ingredient in those simple minerals above enumerated,
and alumina the next. They are mostly silicates and are di-
vided by Dana into three classes.

1. Silicate of alumina and potash form feldspar and mica.

2. Silicate of alumina and lime, with magnesia, form horn-
blende.

3. Silicate of alumina and magnesia form serpentine and
talc, and silicic acid forms quartz.

Sect. 4. Composition of the Rocks.
Rocks are composed of the simple minerals. In some cases,
the minerals may be seen in separate portions, united me-
chanically, as in granite. In other cases they are so inter-
mingled as to conceal their distinct characters, as in green-
stone. Rocks are divided by geologists, according to their
supposed origin, into two separate classes. 1. Igneous
rocks, or those which appear to have been fused by fire.
2. Aqueous rock, or such as appear to have been deposited
from water, or which have resulted from the decay and wear-
ing down of the first class. The igneous rocks are highly

COMPOSITION OF THE ROCKS. . 187

crystalline in their structure ; such as granite, sienite, gneiss,
greenstone, porphyry, basalt, and ancient and modern lava.
They constitute the largest portion of the crust of the globe.
They are destitute of animal or vegetable remains, and hence
are called non-fossiliferous rocks. The aqueous rocks in-
clude the various deposits of clay, sand, gravel, conglome-
rates, sandstones, slates, etc. They are composed, essen-
tially, of the ingredients''of the igneous recks. They contain,
with the exception of a few rocks in the lower part of the se-
ries, the remains of animals and plants, and are hence called
fossilifcrous rocks.

Rocks are subdivided into several groups. The un-
stratified or non-fossiliferous rocks, may be divided chemically
into two. The highly crystalline varieties, usually called pri^
mary, such as granite, gneiss, mica slate and porphyry, form
one class, and the trappcan rocks, such as greenstone, basalt
and trap, form the other class. The difference in their chem-
ical constitution is this; that the first class contain about 20
per cent, more of silex, and from- 3 to 7 per cent, tessof lime,
magnesia and iron than the second class;

The fossiliferous rocks are very various in composition, al-
though they correspond more nearly to the trappean variety
*' in containing less silica and more lime, magnesia and alu-
mina."

The following are some of the most abundant rocks,
composed of the simple minerals.

1. Granite is composed by the mechanical union of quartz,
feldspar and mica. The quartz is in irregular masses, the
feldspar often crystallized, and the mica in thin shining scales.
Hornblende sometimes displaces mica and forms what has
been called sienite.

2. Gneiss is similar in composition to granite, but appears
to be formed by the destruction and deposition of the granite
by water.

3. 3Iica slate is formed by quartz and mica, the latter pre-

188 GEOLOGY AND CHEMISTRY OF SOILS.

dominating so as to give the rock a slaty and shining appear-
ance.

4. The argillaceous slate and clay slate are made up prin-
cipally of quartz and alumina, or argillite, \thich seems to
be decomposed feldspar, containing from 7 to 10 per cent, of
potash.

5. Talcose slates consist of talc, alumina and quartz.

6. Hornblende rocks and hornblende slate are composed
mostly of hornblende.

7. Graywacke is formed of quartz, clay slate and lime.

8. The trappean rocks have a similar constitution.

9. Limestones generally contain clay, feldspar, porphyry
and clay slate, although there are extensive beds of the pure
carbonate of lime.

10. The various sandstones and slates are composed mostly
of silex and alumina, and hence are formed of the minerals
quartz and feldspar.

Sect. 5. Origin of Soils,

Having attended to the manner in which the simple bodies
are united to form the rocks, the way is now prepared to
describe the process by which the rocks are converted into
soils.

The researches of modern geologists have established the
fact, that all soils were originally formed by the disintegra-
tion, decomposition and wearing away of rocks. The rock
has been gradually pulverized, and brought into the condi-
tion of soil. This effect has been produced by the mechani-
cal and chemical agency of air, water, living and decaying
vegetables. This process is constantly going forward.

1. The oxygen of the atmosphere combines chemically with
the metals and decomposable minerals, and, by forming new
compounds, causes them to crumble down. Water also im-
parts its oxygen, and produces a similar effect. The surface

AGENCY OF PYRITES AND WATER. 189

of rocks, in this way becomes pulverized to a greater or less
depth.*

The principal mineral substances with which the oxygen
of the air and of water unite, are iron, manganese and pyrites.

When a rock contains iron or manganese, in a low state
of oxidation, these oxides attract more oxygen from the air
and water,! increase in bulk and split or cleave into their
layers ; thus affording an opportunity for the mechanical
agency of water, either by friction or by freezing.

2. Pj/r/^es, or the bi-sulphuret of iron, exerts the most pow-
erful agency in the decomposition of rocks, and perhaps the
most extensive ; as this mineral is widely disseminated through
nearly all classes of rocks. It is composed of sulphur and
iron. The sulphur attracts oxygen from the air and from
water, and forms the well known substance sulphuric acid
(oil of vitriol). The iron also combines with oxygen from the
same source, and forms an oxide of iron. The acid and the
oxide now unite and produce a new compound, the sulphate
of iron or copperas, a substance capable of being dissolved in
water. Thus the rock, through which the pyrites is dissemi-
nated, is crumbled, thrown or changed in its properties. But
the action does not stop here. The sulphate of iron, being
dissolved in water, which is constantly penetrating the mass,
is brought into contact with feldspar, and both are decom-
posed ; the sulphuric acid in the copperas abandons the iron,
and unites with the potash and lime in the feldspar, forming
sulphate of potash and of lime, while the oxide of iron is de-
posited in the form of iron rust.

* This process is called disintegration, and some examples are
found in Massachusetts, where the gneiss rocks have been penetrated
fifteen feet. The rock is said to rot. Almost every variety of rock is
constantly undergoing this change.

t This action of the oxygen of the air and of water to produce dis-
integration, explains the effect of allowing lands to remain fallow, by
which their fertility in a measure is restored

16*

190

GEOLOGY AND CHEMISTRY OF THE SOIL.

When the pyrites exists m slate rocks, containing much
alumina, magnesia and lime, the sulphuric acid combines
with these bases, by which nearly the whole rock is gradual-
ly converted into soil. Were this the only agent acting upon
the rocks, the character of the soil would be accurately
known, by examining the rock which underlays it ; but this is
rarely the case.

3. The mechanical agency of water, aided by cold and
heat, and by its currents and waves, not only aids in break-
ing down the solid masses, but transports the pulverized ma-
terials in the form of detritus, and deposits them in lower
lands. Thus the substances of different rocks are mingled
together. Freezing water exerts an immense power in this
respect. The water penetrates every seam and crevice of
the rocks, and, by its expansive power in the act of freezing,
forces the parts asunder, and creates new fissures, which are
each year increased in number and width. Nor does this
influence cease after the rocks are fully converted into soils ;
each year the expansive force of water tends to pulverize, and
render the earth light and porous.

The friction of running water wears off" the rocks, and re-
moves that which has become broken down by chemical ac-
tion. The particles being suspended are carried down by
the force of the stream, and deposited along the banks and at
the mouths of rivers.

That the agency of water, at some ancient period, has ex-
erted a very great influence upon the rocks and soils appears
from the fact, that over the whole northern hemisphere, the
rocks and soils have nearly all been removed in a southerly
direction, and the materials of different formations variously
mingled together. This has been shown to have resulted
from the action of glaciers, by which the whole surface has
become scratched, and the sand, gravel and boulders rolled
up into hills, with ponds and vallies between.

4. Decaying plants tend to convert the rocks into soils.

AGENCY OF GROWING PLANTS. 191

The vegetable acids are capable of combining with the lime,
soda, ammonia, potash, magnesia, oxide of iron and manga-
nese. These bases are thus withdrawn from the rocks, and
the latter crumble to pieces, and salts are formed, which are
useful in the ^^nourishment of future generations of plants.
During decay, large quantities of carbonic acid are formed.
This acid is not only direct food for plants, but is capable of
combining with the potash in the feldspar of granitic rocks,
and of facilitating their decomposition. This acid is the
most powerful agent in its action upon the alkalies, even de-
composing the silicates and forming soluble salts.

5. Groicing plants exert the most powerful agency in de-
composing the rocks. Not only do the lichens, mosses and
other plants insert their roots into the crevices of the rocks,
and by keeping them moist, favor the chemical action of air
and water, but the living plant forms with the rock or soil a
galvanic battery, of immense power ; by this means the
plant is enabled to obtain from the soil those ingredients
which its wants may require. This is proved by the fact,
that plants, growing in glass vessels, will decompose the glass
to obtain the potash, of which the glass is in part composed.
It is highly probable, that a greater amount of decomposition
is produced in this way than by all other causes together.
Similar to this influence, if not identical with it, is what has
been called " catalysis of life ^ The living plant acts by its
presence to decompose the rocks, and to effect rapid changes,
which not only convert them into the state of soil, but form
the elements into different substances.

The above process will serve to illustrate the chemical and
mechanical agencies which are constantly at work tq crumble
down the solid rocks, and bring them into a state fit for the
support of the vegetable kingdom. These agents are con-
stantly active. The great effect of stirring the soil, is to fa-
cilitate the decomposition of the rocks, and of the vegetable
bodies which are always present in the soil. But for this

192 GEOLOGY AND CHEMISTRY OF SOILS.

agency, the soils in a few years would become exhausted of
all their alkalies, the vegetable matter would not decay, and
hence no food in the soil would be provided for the plant.
Absolute barrenness must therefore succeed. For without
alkalies or alkaline earths and geine, no plants can grow.

Depth of soil. The influence of the agents above de-
scribed, has not extended to an average depth of more than
15 feet ; although in some places, the soil is actually more
than a hundred feet in depth. This is but a small por-
tion of the whole mass of the earth, whose mean diameter is
7,911 miles; hence "the soil would be less in proportion to
the whole earth, than the slightest tarnish of rust on an iron
globe 100 feet in diameter compared with its mass." But a
small part of this constitutes what is properly denominated
the soil. That part only of the surface, varying from 3 to 20
inches in depth, which has become mingled with vegetable
and animal matters, constitutes the true soil, and it is most-
ly this part, which concerns the farmer, and which is pre-
sented for our investigation, classification, description and
improvement.

CHAPTER V.

SOILS AND THEIR RELATIONS TO VEGETATION. THEIR ANAL-
YSIS, COMPOSITION, MUTUAL ACTION OF THEIR ELEMENTS,
GEOLOGICAL AND CHEMICAL CLASSIFICATION AND DESCRIP-
TION.

The relation, which the soil sustains to vegetation, has
been pointed out in a general way in the first chapter, p. 81,
where it was shown to be one of the essential conditions to
the action of the vital power in those vegetables which were
cultivated for the use of man ; furnishing support for the roots,

ANALYSIS OF SOILS. 193

a medium for the circulation of water, and for those chemical
and electrical changes which must take place, before the nu-
triment could be prepared and introduced into the vegetable
organs ; and yielding, by its salts and mineral ingredients,
both food and stimulus to growing plants. It was remarked,
however, that all soils did not perform these offices with the
same degree of fidelity, but a few were fitted, without artifi-
cial appliances, to facilitate the vigorous action of the vital
principle, and the perfect development of all the vegetable
organs.

We propose now to consider the soil as a specific subject
of investigation, to give the modes of its analysis, to point out
its chemical and geological character, and the relation of each
variety to the cultivated crops. By this method, the intelli-
gent agriculturist may learn the nature of his soils, the gene-
ral mode of improvement, and howto adapt his crops to such
as are fitted by nature or art to yield the most bountiful crops.

Sect. 1. Analysis of soils.

The importance of a correct knowledge of the constitu-
ents of any soil, appears from the fact, that without it, all ex-
periments must be conducted in the dark.

A w^ant of such knowledge, has given rise to the various
discrepant views of farmers, relative to the application of cer-
tain salts of lime. Experiments are tried by one farmer, and
he is successful; another applies the same substance and
fails ; hence we have the most contradictory accounts of
nearly every mode of improvement, and the consequence is
that, though there are constant improvements, in individu-
al cases, no generalization can be made applicable to every
kind of soil. An analysis of a soil will indicate at once the
mode of treatment. There can be no doubt here, as the most
fertile soils of our own and of other countries, have already
been analyzed, and their composition accurately ascertained.

Any farmer, then, who can analyze his soil himself, or pro-

194 GEOLOGY AND CHEMISTRY OF SOILS.

cure it done by some scientific chemist, may compare its
composition with that of fertile soils, and the exact mode of
improvement will be seen at a single glance. This excludes
all empyricism, all hap-hazard experiment, all unnecessary ex-
pense,* and, for a trifling sum, will ensure complete success.
The grand desideratum, in this, as well as in every other
art, is the the union of thcorij and practice. Agriculture
should not be pursued as a mere art, a routine of mechani-
cal drudgery, but the scientific principles upon which the
success of the art must ultimately depend, should be thor-
oughly understood by every farmer.

Why should the agricultural community be the only class
who are not educated in the science of their profession ?
Why should they suffer their art, the first and the most im-
portant of all others, to rank lowest in the scale ?t

It is not expected, that every farmer will have a labora-
tory, furnished with all the materials necessary to a complete
and accurate analysis of his soils. This must be left to a
few practical chemists, but the rising generation of farmers,
may very easily obtain such knowledge, as will enable them

* For the trifling sum of ten, or at most, twenty dollars, almost any
farmer can ascertain the composition of any of his fields, and have the
mode of improvement pointed out. This, without doubt, would be
more than returned to him in a single season, and would be increas-
ed in tenfold proportion in succeeding years. Were half the time
and money, which have been wasted in useless experiments, without
any scientific principles to gnide, expended for the purpose of analy-
sis, our farmers would, long ere this, have had the satisfaction of see-
ing their farms gradually, but surely, arriving to a state of fertility,
of which they had never dreamed ; and instead of going West to seek
more fertile lands, would actually be able to compete with the West-
ern farmer in any market under lieaven.

t If, with the rapidity of improvement among every other class,
our farmers do not take care of their interests, by improving their
minds and studying their professions, they must be looked down up-
on, and justly too, as the lowest in the scale of being; as incapable of
a higli state of civilization.

MECHANICAL ANALYSIS OF SOILS. 195

to make examinations which will indicate the course of im-
provement. They may learn all that is absolutely essential
to the highest success in their profession, and that which
will not only prove the means of a competency for themselves
and families, but which will also furnish the highest means
of intellectual and moral improvement, and the sources of
increasing influence and happiness. This section will there-
fore be devoted to the description of several modes of analy-
sis, for the purpose of learning the composition of various soils.
It may serve also to convince the farmer, that whether he
is able to adopt any of the modes himself or not, the subject
is one which appeals, not only to his intelligence, but to his
interest, and to the dignity of his profession.

I. Mechanical analysis and tests.

The mechanical analysis of soils may be performed by
any man " capable of driving a team or holding a plough."

Apparatus. The apparatus required for a mechanical
separation of the particles of a soil, are 1st, two sieves,* one of
copper wire, with meshes -^^ of an inch square, and the oth-
er of fine gauze, with meshes -^^^ of an inch in diameter. 2d,
A glass jar, or common glass bottle. 3d, A balance, capable
of turning with a grain weight, and a set of weights, from 1
to 1000 grains.^ The whole need not cost more than fifteen
or twenty dollars.

Process. Having selected 1000 grains of soil to be an-
alyzed or tested, heat it, for twenty minutes, at a tempera-
ture just below that at which straw turns brown, so as to
evaporate the water. Weigh the soil again, and the loss
will give nearly the quantity of water which the soil is ca-
pable of absorbing. It is important to note this, as some
knowledge may be obtained from it, useful to the farmer.
For example, it is found that those soils which absorb the

* Sieves brought from Canton, and sold by apothecaries,
the purpose very well.

answer

196 GEOLOGY AND CHEMISTRY OF SOILS.

most moisture, are richest in vegetable mould or geine, and
by comparing this power in different soils, we may arrive at
valuable knowledge as to their comparative fertility.

2. The next step in the process is to bruise the whole, so
that no lumps can be found in it, and then sift it through the
coarse sieve. What remains too coarse to pass through, will
consist of pebbles and fibres of wood. This may now be
weighed and tested. The pebbles may be broken with a
hammer, and their nature ascertained by inspection, or they
may be tested by acids.

To test them by acids, a few grains may be bruised, if
need be, put into a clean glass, flask or tumbler, and cover-
ed with water. Half as much hydrochloric (muriatic) acid as
water may be added, and if they are calcareous, small bub-
bles of gas will pass up through the water. If they are
wholly carbonate of lime, the acid will completely dissolve
thefti. But this is not to be expected in any of our soils.
It is very rare, that the least trace of carbonate of lime will
be found in this portion. If the coarse parts do not effer-
vesce with acids, they are composed entirely of silica and
alumina, or of a mixture of both, which is generally the case.
These two bodies may easily be distinguished from each oth-
er. The silica is rough like sand, scratches glass, etc., and
the alumina is soft and unctuous to the touch. If any ani-
mal or vegetable substance is mixed with the coarse parti-
cles, by burning a portion of them, the odor of peat or sponge
will be given off, then by carefully weighing a quantity
before and after burning, the amount of organic matter may
be ascertained.

3. Sift the soil again through the fine sieve, and weigh
the quantity which remains in the sieve. It will consist of
sand and fine vegetable fibres. This may be tested in the
same way with the coarser particles, and the amount ascer-
tained.

Take now the fine powder, which passes the gauze sieve,

MECHANICAL ANALYSIS OF SOILS. 197

and agitate it for a while in a given measure of water, pour
off the suspended matter upon a filter.* This will consist
mostly of vegetable substances, clay and fine sand. By ex-
amining the residue in the glass jar, the larger particles of
the mineral ingredients can easily be detected. Put the con-
tents of this jar on the other filter, and after the water has pas-
sed out, the filters with their contents may be weighed, and the
relative proportions determined. If the filter contain free acid,
little lime water will cause a white precipitate, which is either a
sulphuric or carbonic acid ; if the latter, the precipitate will
effervesce with sulphuric acid, and will be converted in-
to gypsum, or sulphate of lime. To ascertain whether there
is any sulphate of iron or copperas, pour into the liquor a
few drops of the infusion of gall-nuts, and it will give a dark
or brown color.

To test for oxide of iron, wash the filter, containing the
clay and fine particles, with diluted muriatic acid, and apply
the infusion of galls ; and if it becomes black, it contains
iron.

The above process can be easily performed, and some val-
uable knowledge obtained. It may be known, for example,
whether the soil is mostly silica or alumina, or whether it
contains free acid, like the sulphuric, or whether the acid is
combined with oxide of iron, a substance very injurious to
vegetation ; but which is, by the application of lime to de-
compose the copperas, easily converted into gypsum (sul-
phate of lime), a valuable manure. The above method, how-
ever, cannot be depended upon where accuracy is required,
and we will now proceed to describe a method of analysis
which is very simple, and which some farmers may be able
•to adopt. It is substantially the method of Dr. Samuel L.
Dana, of Lowell, Mass.

* The filters may be made of fine linen cloth, of equal weights,.
placed in a common glass tunnel, and lined witii unsized paper.
17

ipS GEOLOGY AND CHEMISTRY OF SOILS.

II. Chemical Analysis of Soils.

Object of this analysis. The object of this analysis is to
ascertain the water of absorption ; the quantity of soluble
geine, which will indicate the quantity of food already pre-
pared for vegetables ; the amount of insoluble geine, which
will show what food is unprepared as yet for the plant ; salts
of lime and mineral constituents. The latter may all be re-
duced, according to Dr. Dana, to granitic sand; that is, the
earthy ingredients of all our soils, are composed of the fine
detritus of granite, gneiss, mica slate and argillite. Now, as
these earthy ingredients may vary considerably in their pro-
portions, without affecting the fertility of the soil, they are al-
ways prepared for their office, and are only changed for the
better by cultivation. But this is not the case with salts and
geine. Any considerable variation here, will cause barren-
ness. Salts and geine are the substances which are remov-
ed by the plant, and must therefore be constantly supplied to
the soil, or the land will soon become exhausted. The great
object then of analysis, is to determine the quantity of solu-
ble and insoluble geine and salts. This is all the farmer
needs to know, which may not be learned by inspection of the
soil, or by the descriptions which have already been given.
The relations of the soil to heat and moisture, depend chief-
ly upon geine. The larger the quantity, the greater the ab-
sorbent power of the soil, both as respects water and ca-
loric.

Mode of Analysis. 1. To determine the absorbent power
of soils, sift the soil through a fine sieve, and take a quantity
of the finer portions, and heat it to 300° F. Then weigh out
100 grains on a piece of glazed letter-paper, expose it to the at-
mosphere from 24 to 3G hours, weigh again, and the quan-
tity gained will be the absorbent power of the soil. Note
this in a Journal kept for the purpose.

2. To determine the quantity of soluble geine. Bake the

CHEMICAL ANALYSIS OF SOILS. 199

soil, which has passed through the finer sieve, just up to the
point at which paper becomes brown, but not sufficiently to
scorch it. Weigh out 100 grains of the baked soil, as above,
and boil it for half an hour, in a solution of .50 grains of sale-
ratus, or carbonate of potassa,* dissolved in 4 oz. of water.
When it has settled, the clear liquor may be poured off, and
the residue washed in 4 oz. of boiling water.

The whole is now to be thrown upon a filter, which should
be previously dried at the same temperature with the baked
soil, and carefully weighed. Wash the soil upon the filter
until the water passes through colorless. If carbonate of am-
monia is used, instead of washing the soil, it should be di-
gested with the same quantity of the solution, at least twice,
and then washed until there is no alkaline reaction in the
water as it passes the filter. Mix all these liquors together,
and they will form a brown-colored solution containing all the
soluble geine. The sulphates have been converted into car-
bonates, which, with the phosphates, are on the filter with the
soil. Dry the filter, raising the heat gradually to above that
of boiling water, and then weigh the contents. The loss is
the quantity of soluble gcine. Note this also, and mark the
filter 2.

3. To test the accuracy of the analysis thus far, precipitate
the geine from the alkaline solution, with excess of lime-wa-
ter. The geine will combine with the lime, forming the ge-
ate of lime, and when a sufficient quantity of lime-water has
been added, the liquor will be colorless. Throw the whole
upon a weighed filter, and wash with a little acetic, or very
dilute hydrochloric acid, and this will combine with the
lime, and pass through the filter, leaving the geine quite pure.
Dry and weigh as before. If this quantity corresponds with

* Dr. C. T. Jackson objects to carbonate of potassa, because it is
impoissible to wash out the last traces of it from the vegetable fibre,
and because the subcarbonate of potassa takes up a portion of the alu-
mina.

209 GEOLOGY AND CHEMISTRY OF SOILS.

that by the first process, there can be no doubt of the accu-
racy of the result.

4. Place the filter (2) with its contents upon a funnel, and
wash with 2 drams of muriatic acid, diluted with 3 times its
bulk of cold water. Wash the filter, until tasteless water
passes through. The acid will dissolve the carbonate and
phosphate of lime; the iron which may arise forming salts of
iron, present in the soil ; and the oxide of iron. The two
latter exist in very small quantities in most soils, and as the
sulphuret and sulphate of iron, in the process of cultivation,
are converted into sulphate of lime, the whole may be re-
garded as a solution of the salts of lime. Evaporate the solu-
tion to dryness, weigh it, and it will give the quantity of these
salts.

5. To separate these salts, dissolve them in boiling water.
A part will be insoluble. Throw the whole upon a filter, and
weigh as above. The insoluble portions will be phosphate of
lime, and the loss will be the sulphate of lime. Note the
quantity of each.

6. To determine the quantity of insoluble geine. The re-
sidual soil may now be burned in a silver or platina crucible,
and the loss of weight will give the quantity of insoluble geine
contained in the soil. The only source of error here, will be
due to the loss of water in any hydrate which may exist in the
mass burned. But it is found by experiment, that in our
soils the quantity is rarely sufficient to affect materially the
result.

7. The weight of the mass after calcination is *' granitic
sand," composed mostly of clay, mica and quartz, all of
which may be tested by methods already given.

It will be seen, that by this process the quantity of lime is
not detected, but this is of very rare occurrence in the soils
of this country. From an analysis of one hundred and twen-
ty five specimens of soils, taken from as many towns in Mas-
sachusetts, only seven contained any quantity of carbonate of

CHEMICAL ANALYSIS OF SOILS. 201

lime, and from the analysis of a great variety of soils in New
England and the Western States, only a few have any nota-
ble portions of this substance, although reposing upon lime-
stone rocks. The advantage, therefore, of ascertaining the
quantity of this substance, may be derived from simply test-
ing the soil with acids ; a method already described. If
now the results of this analysis are summed up,' they will be
arranged in the following order :

1. Water of absorption 4.4

2. Soluble geine 5.1

3. Phosphate of lime 0.6

4. Sulphate of lime 1.6

5. Insoluble geine 7.5

6. Granitic sand 85.2

The numbers are supplied from an analysis of 100 grains
of a fertile soil in Andover, Mass.

The method of analysis employed by Dr. C. T. Jackson,
differs in some particulars from that of Dr. Dana. The
method employed in the analysis of the soils of Rhode Island
is here inserted.

1. Having weighed out a certain quantity, say 100 grains of
the fine soil, that has passed the finest sieve, it being weighed
upon a square piece of glazed letter-paper, the first step is to
dry it thoroughly at a temperature above boiling water, but not
sufficient to scorch the paper. The soil being again weighed,
its loss of weight is water, and the amount is noted in the la-
boratory journal, A.

2. To ascertain the quantity of organic matter, whether of
vegetable or animal origin, we place the dried soil in a platina
crucible, cover it closely, and heat it gradually to redness, over
an alcohol lamp. By the odor disengaged during the process,
we know whether the organic matter is of a vegetable or ani-
mal nature, the former having the smell of burning peat, and
the latter that of burnt feathers. It is, however, difficult to dis-
tinguish the mixed odors, without much practice. Having
charred the organic matter, it may now be safely burned out,
by placing the open platina crucible with its contents in a clay
muffie, open at one end, and exposed to a full red heat. The
air circulates in this muffle, and soon burns away all the or-
ganic matter, which may be ascertained by repeatedly stirring the
soil with a platina rod during its combustion, and noting wheth-
er any more particles are burning. After the operation is com-

17*

202 GEOLOGY AND CHEMISTRY OF SOILS.

plete, weigh again, and the loss of weight is the amount of or-
ganic matter in the soil. Note it in the laboratory journal, B.

3. To determine the amount and nature of matters soluble
in muriatic acid, which will take up all the mineral substances
that can be acted upon by vegetation, such as all salts of lime,
iron, alumina, manganese, magnesia, potash, etc., place the
burned soil B in a clean green glass flask, with a thin bottom,
pour over it a small quantity of distilled water, sufticient to
cover it, then drop in some muriatic acid, and note whether
there is any effervescence. If so, there is a carbonate, proba-
bly of lime, in the soil. Add more acid, say about one ounce,
diluted with an equal bulk of water. Boil tlie whole, for half
an hour, or until the residuary matter is nearly white. Every
thing soluble in the acid is then taken up. Dilute with
distilled water and throw the whole upon a double filter. Af-
ter the hquid has passed through the paper wash the insoluble
matter on the filter by means of a stream of boiling hot water,
and continue the operation until the water comes through taste-
less. Dry the filters with their contents, separate them and
bm-n them separately, weighing one against the other. The
difference is the weight of the insoluble silicates, and is gener-
ally nearly pure si lex. Note its weight, C.

4. In order to ascertain the nature and proportions of the
matters that have been dissolved by the muriatic acid, you may
proceed as follows :

Take the filtered solution, which must be in a green glass
flask ; add to it a few drops of nitric acid, to per-oxidize the
iron, and boil it. Then, while still warm, add liquid ammonia,
until all the per-oxide of iron and alumina are precipitated. Sim-
mer the whole a few minutes so as to condense the bulky pre-
cipitate. Filter on double paper, wash the precipitate twelve
hours with hot water, or until the liquid passes tasteless ; then
separate the })recipitate while moist from the filter by means of
a silver knife, scraping up every portion that can be removed
from the filter. Place this in a large silver crucible and pour
over it a solution of pure potash, in distilled water. Boil until
the alumina is entirely taken up, and the oxide of iron left has
a deep brown color. You may know that a sufticiency of pot-
ash has been added by letting fall into the solution a drop of
muriatic acid, when flocculi of alumina will preci[)itatp, but will
immediately redissolve if there is potash enough. Dilute with
distilled water, filtrate through double filters, wash the precipi-
tate, dry the filters and their contents, sej)arate them, and burn

CHEMICAL ANALYSIS OF SOILS. 203

and weigh them against each other. The difference of their
weight is that of the per-oxide of iron. Mark its weight
against D.

5. To separate the alumina, you must now take its alkaline
solution and acidulate it with muriatic acid ; then add a solu-
tion of carbonate of ammonia in pure water. All the alumina
will be thrown down in the state of a white, gelatinous, and
flocky precipitate. Collect it on a double filter, wash it for 24
hours with boiling distilled water, dry it, separate and burn the
filters. Weigh one against the other, and the diflference of
their weight will be the weight of the alumina. Mark this
against E.

Now you may go back to the ammoniacal solution, from which
the iron and alumina have been separated, but in practice the
following processes are carried on while we are waiting for the
filtralions and washings of the alumina and oxide of iron.

This ammoniacal solution may contain the lime, magnesia,
and a small quantity of manganese. Add to it a solution of ox-
alate of ammonia which will precipitate all the lime in the
state of an oxalate. Let this precipitate subside, and then col-
lect it on double filters, washing it with warm water. Dry the
filters with their contents, separate them and burn one against
the other at a red heat in a platina capsule ; let fall a few drops
of a solution of carbonate of ammonia upon the lime, heat it
again to dull redness. Weigh the result against its counter-
poised burnt filter, and you will have the quantity of lime in
the state of a carbonate, and may reduce it by calcidation to
any other salt of lime that you have found to exist in the soih
Mark the weight of this against F.

6. To separate the magnesia, add to the solution from which
the lime has been separated, a solution of phosphate of soda,
(it being still ammoniacal,) when the magnesia will be thrown
down in the state of an ammoniaco-iiiagnesian phosphate. Col-
lect it on a filter, wash it but little, then dry the filters and con-
tents, separate them, burn one against the other in a platina
capsule. The difference of weight will be the weight of the
bi-phosphate of magnesia, 40 per cent, of which may be re-
garded as equivalent to the magnesia contained. G.

7. You may now run a current of sulphureted hydrogen gas
through the remaining solution, or add bi-hydro sulphate of am-
monia, when all the manganese will be thrown down in the
state of a sulphuret. Collect and reduce it to black oxide. H.

The analysis is complete so far as it can be done on this spe-

204 GEOLOGY AND CHEMISTRY OF SOILS.

cimen, and you may sum up your results, and see liow nearly
' they will balance, and if there is a loss, you must make another
examination for salts of potash and soda, in the manner I shall
give presently. Let us first sum up the above operations.

A Water of absorption.

B Organic matter.

C Insoluble silicates.

D Per-oxide of iron.

E Alumina.

F Lime.

G Magnesia.

H Manganese.
In order to ascertain the existence of alkaline salts, burn off
the vegetable matter from another 100 grains of the dry soil.
Then pour over it a little nitric acid, and digest it at a boiling
heat. Dilute and filter the solution, evaporate it to entire dry-
ness, fiise the saline matter obtained, and drop into it a few
fragments of prepared pure charcoal. If nitrates are present,
deflagration will take place, and the alkaline bases will be con-
verted into carbonates. Dissolve the residue and test a drop
of the solution by means of a solution of chloride of platina and
soda. If potash is present, a yellow powder will precipitate,
but none will fall if soda alone is present.

Sect. 2. Composition of Soils as cUter mined hy Analysis.
The composition of soils might generally be deduced from
the composition of the rocks out of which they are formed,
provided no chemical nor mechanical changes were wrought
upon them in the process of disintegration. But as the
proportion of the ingredients are changed in this process,
as some of the alkalies are abstracted by growing plants, or
removed by successive crops, and as organic matters are
added, we must resort to an examination by analysis, in or-
der to ascertain the exact composition of any soil which is
presented for our inspection. By this examination, soils are
found to be composed of two parts: 1. the mineral ingredi-
ents, or inorganic portions, which include the alkalies, metal-
lic oxides, salts and earths ; 2. the vegetable and animal

MINERAL CONSTITUENTS OF SOIL. 205

I. Mineral constituents of soils. The mineral substances
which enter into the composition of all soils, are few in num-
ber, and most of them easily detected. They may be divided
into 3 classes : 1. earths ; 2. alkalies and metallic oxides ;
3. salts and urets.

As the rocks are mostly made up of silica, alumina, lime
and magnesia, the great mass of the soil is composed of these
substances, which are commonly called earths. The alkalies,
potassa, soda and ammonia, the metallic oxides of iron and
manganese, exist in all fertile soils in small quantities. The
phosphates of lime and magnesia, nitrate of potash, sulphates
of lime and ammonia, chloride of sodium, carbonates and
other salts, are almost always present in soils ; and, in some
cases, sulphurets, phosphurets and carburets of iron exist in
very small quantities.

In one view of the subject, the soils are a mass • of
salts, mostly silicates, silicic being the most abundant and
most powerful acid in nature. We should expect, from the
composition of the simple minerals which form the rocks, that
the soils, considered chemically, would be a mass of silicates.
But it will be a more practical view, and better accord with
the general representation of agricultural writers, to describe
silicic acid among the earths, alumina, lime and magnesia.
We have already described these earths, in their principal
chemical characters and in their relations to the rocks. We
come now to consider them agriculturally, and shall notice
their amount in soils, their relations to the vegetable king-
dom, and their fitness to perform the duties assigned them in
the vegetable economy.

When soils are examined by chemical analysis, they are
found to be composed of the following mineral substances.

1. Silica or silicic acid, also called silex and siliceous earth,
constitutes about 40 or 45 per cent, of the crust of the globe,
and 66 per cent, of all the rocks and soils of New England.
This proportion varies but slightly, with regard to all soils,

206 GEOLOGY AND CHEMISTRY OF SOILS.

capable of sustaining a healthy vegetation, with the exception,
perhaps, of limited portions of calcareous and peaty soils, in
which the proportion is much less, but generally greater than
66 parts in 100.

The properties of silica render it well fitted to form so large
a portion of the soil. It is nearly insoluble in water, and
hence is not liable to be washed away by rains. In fact it is
not dissolved by any acid found in the soil, unless it be the
crenic and hydrofluoric, in which state it may be introduced
into the organs of plants. Silica is not an acid, by the chemi-
cal tests, because of its insolubility. It however combines
with the alkaline bases, with the earths and metallic oxides,
and is the most powerful electro-negative element in the com-
position of the soil. It acts in the soil as an acid, and bal-
ances, by its negative character, almost the entire mass of the
electro-positive earths, alkalies and metallic oxides. Its power
of absorbing and retaining water, is very slight, and hence
when it is the principal ingredient of a soil, it imparts to it a
porous, dry and light character. The relations of silica
to vegetation are highly interesting. It is almost the only
ingredient of soils which gives to them the property of per-
mitting the roots of plants to extend themselves in all direc-
tions, and forms as we have seen, p. 175, a part of the vege-
table structure. Silica thus furnishes the principal support
to the cultivated grains and grasses, and defends them from
the action of atmospherical and other agents.

2. Aluminous earths. Alumina, a sesquioxide of alumina,
is composed, as we have seen p. 175, of 27.4 parts by weight
of the metal aluminium, and 24 parts of oxygen. It is found
in every region of the globe, and in the rocks of all ages. It
results from the decomposition of the feldspathic minerals or
argillaceous rocks. The different kinds of clay of which
bricks, pipes and earthen ware are made, consist of hiclratc
of alumina, that is, of alumina combined with water, and of
a small portion of silica. Aluminous earth is next to silica

MINERAL CONSTITUENTS OF SOIL. 207

in quantity, and constitutes but about 16 per cent, of all the
soils in New England. It varies greatly in different varieties
of soil, though it is never absent from any. Pure alumina,
however, does not exist in the soil. It is generally combined
with silica, and with organic acids, such as crenic and apo-
crenic acids, and geic or humic acid.

The properties of aluminous earth make it a fit associate
for silica, in order to give the proper texture and adhesive-
ness to the soil. Like silica, it is insoluble in water. But
its action upon the roots of vegetables, is just the opposite of
silica, giving the roots their basis of action and support,
and preventing them from penetrating too far. It retains the
water with great force, but yields it to the plant as its wants
may require. In consequence of its pow er of absorbing and
retaining water, when it constitutes a large proportion of the
soil, it is unfriendly to vegetation, forming a soft, ductile paste,
which excludes the air in wet weather, and contracts and
bakes in seasons of drought. As it contracts by heat, the
delicate fibres of the roots are injured in the fissures thus
formed, by exposure to the cold, heat and water.

Aluminous earth is still more nearly allied to vegetables
by forming a part of their structure. The ashes of some
plants contain very small portions of it. It is also found in the
seeds of some grains. It is capable of acting the part, both
of an acid and of an alkali, a circumstance which renders it
probable, that its chief agency in the soil, is to act upon the
vegetable matter, and convert it into veoetable food. Alu-
mina is farther serviceable, from its possessing the property
of absorbing gaseous bodies, such as ammonia, and of retain-
ing in the soil for the use of the plant, what would otherwise
escape into the air. The fermentation of manures in the
soil, yield several gases, which are retained in this way.

3. Lime. Lime is also widely disseminated in nature. It
forms the basis of extensive mountain ranges, and of a large
portion of the cultivated surface of the earth. It exists, how-

208 GEOLOGY AND CHEMISTRY OF SOILS.

ever, not in its pure or caustic state, but combined with acids,
forming with carbonic acid the carbonate of lime (marble),
which is the most abundant. In this form, it constitutes about
^ part of the crust of the globe. The sulphate (common plaster)
is next in abundance, and the phosphate is diffused through all
soils, and is the source from which animafls obtain their bones.
The pure or quick lime is generally obtained by heating the
carbonate in kilns, until all the carbonic acid is driven off. It
will then unite with water, and form a white bulky hydrate,
called slacked lime, used for mortar.

The quantity of lime, found in the soils of this country, is
generally very small. From an analysis of the soils of Mas-
sachusetts, as contained in the report of Prof Hitchcock,
lime, in the form of carbonate, sulphate and phosphate, does
not upon an average exceed 3 per cent. The sulphate is
the most abundant, varying from 0.1 to 3.9 per cent.

The carbonate of lime, with the exception of one soil, in
Truro, which contains 21.3 per cent, varies from mere traces
of it, to 6 per cent, ; but generally there is much less than
2 per cent., and not one soil in twenty, contains a single par-
ticle of lime in the state of carbonate. The amount of phos-
phate is not accurately determined, but the proportion in
most soils is less than 1 per cent. The soils of Rhode Isl-
and, according to the analysis of Dr. C. T. Jackson, do
not, upon an average, contain 1 per cent, of all the salts of
lime, and scarcely 1 per cent, is found in the soils of New
Hampshire.

Soils from the Western, Middle, and Southern States, al-
though from lime-stone regions, rarely contain a larger pro-
portion of lime, in any form than is found in New England.
It appears from an analysis of five specimens of soil from Il-
linois and Ohio, that all the salts of lime amounted, upon an
average, only to 4.9 per cent.

In other countries, soils are frequently described, contain-
ing from 6 to 30 per cent, of the carbonate alone. In this

MINERAL CONSTITUENTS OF SOIL. 209

respect, then, our soils are peculiar, and hence the great im-
portance attached to this substance as a manure. (See im-
provement of the soil.) The reason why so small a quantity
of carbonate of lime is found in our soils, compared with those
in other countries, is ascribed by Prof. Hitchcock to the fact
that growing plants abstract it, and that our lime rocks are
not so easily reduced to the state of soil by the ordinary
agents of disintegration.

The influence of lime upon growing vegetables is not, in
this country, due to the texture which it gives to the soil, for
in most cases, the quantity is not sufl[icient to render a heavy
soil light, or modify the influence of too great a quantity of
siliceous sand. Its influence is probably threefold. 1. It
tends to convert the vegetable matter into vegetable food,
thus performing the office of a solvent, or converter of innu-
tritious matter into nutriment. 2. It corrects the acidity of
soils, by uniting with free acids, or decomposing poisonous,
metallic salts. 3. It forms a part of the vegetable struc-
ture, and is properly inorganic food. Like all other alkalies
it also contributes to electrical effects, which may be regarded
as a kind of stimulus to the vital functions. It is found, as
we have seen, in the vegetable productions, sometimes uni-
ted with organic, and at others, with inorganic acids.

4. Magnesia. Magnesia is found in serpentine in the
form of a silicate, in steatite or soap-stone, talcose slate, in
magnesite, sea water, certain limestones, called magnesian
limestone or dolomite. Although generally found in soils, it
never constitutes but a small portion of them. The quan-
tity is given in but a hw of the soils of Massachusetts, and
varies from .25 to 2J per cent, from which it is inferred, that
only traces of it exist. In the soils of Rhode Island, the
amount of magnesia is rarely 1 per cent. ; often none at all,
or only traces are found. A few soils contain 4 per cent.
In New Hampshire less than 1 per cent, is found, and in
Maine, out of thirty-five soils analyzed, only one contained
18

210 GEOLOGY AND CHEMISTRY OF SOILS.

any magnesia, and that contained 3 per cent. It must, how-
ever, exist in all fertile soils, as it enters into the composition
of many varieties of grain. The kernel of corn could not
be formed without the presence of the phosphate of magnesia.
Magnesia, like lime, does not generally constitute a suffi-
ciently large portion of the soil to affect its texture. "When
it does it has the properties of clay, absorbing moisture and
imparting its adhesive properties. It acts as an alkali, to
convert vegetable matter into food, and constitutes a part of
the vegetable structure. When applied in its caustic state,
it has been found injurious to vegetation ; but as a carbonate,
it is highly useful. Like lime, it must be regarded as an im-
prover of the soil, as a manure, rather than an earth.

The union of these four earths in a soil, give to it gener-
ally the properties of each. But as they are combined in
the soil with each other, and with other substances, in the
form of salts, we cannot infer with certainty the exact char-
acter of the soil, by knowing in what proportions they ex-
ist ; but we must know in what state of combination they
are found. It will be seen that silica and alumina constitute
almost the entire mass of the earthy ingredients of all our soils,
and the qualities of a good soil will depend upon the right
proportion of these substances. But there are other inorganic
bodies found in soils, as essential to fertility as any that have
been described.

2. Alkalies and metallic oxides, contained in the soil. The
most important, and almost the only substances under this
head, are ammonia, potash, soda, oxide of iron and manga-
nese.

Ammonia has been shown by Liebig to exist in the atmos-
phere, in very small quantities; of course, inconsequence of
its solubility in water, it is found in all soils. It has been
supposed, that ammonia was a product of the putrefaction of
animal and vegetable substances, containing nitrogen. But
Liebig believes, that it belongs to the original formation of

MINERAL CONSTITUENTS OF SOIL. 211

the matter of the earth, and Daubeny points out its source as
proceeding from volcanic action. The exact amount in the
atmosphere or the soil has not been accurately determined.
It is found in iron-rust, clay, etc., and is retained in the soil
in the form of sulphate, carbonate, humate, etc.

Its relations to vegetation are of the highest importance.
According to Liebig, it is the only source of the nitrogen of
plants. Others regard it as the solvent of geine, and the con-
verter of the vegetable matter into food ; and some add, that
it stimulates the functions of plants. Its action has already
been considered in the third chapter.

Potassa or potash. Pure potassa is not found in soils. It
is a well known alkali originating from several rocks, in
which it exists mostly in combination with silicic acid {sili-
cate of potash), but it is also found combined with several
other acids.

The minerals which supply potash to plants are numerous
and widely diffused. All the aluminous minerals contain it.
Feldspar, a constituent of granite, contains I7:| per cent.
Basalt contains from |^ to 3 per cent., clay-slate from 2.75 to
3.36, and loam from IJ to 4 per cent. Hence we should
expect to find potash in large quantities in the soil ; but owing
to the action of growing plants which eliminate the potash, soils
which have been cultivated for some time, contain much less
than might appear from its abundance in the rocks. This is
a case, in which analysis must be resorted to, in order to de-
termine the exact amount of an ingredient. In the recent
analysis of the soils of New England, we have been unable to
find potash as an ingredient, although it must exist in all our
soils in a greater or less quantity, locked up in the minerals.
Dana estimates its amount in the soil, composed of granitic
sand, to be 36 tons per acre, 6 inches in depth. In some
soils, it is found to constitute from 5 to 10 per cent.

The relation of potash to vegetation is similar to all alkaline
substances. It is a powerful converter of vegetable matter

212 GEOLOGY AND CHEMISTRY OF SOILS.

into the food of plants. It neutralizes acids, and, by uniting
with silicic acid, forms the outer covering or epidermis of
the grains and grasses. It is found in all plants in considera-
ble abundance, and is one of the greatest fertilizers of the
soil. Plants, as we have frequently remarked, eliminate it
from the rocks by galvanic action ; decomposing vegetable
matter also abstracts it ; the ordinary action of the air, wa-
ter, and many other agents: hence the use of clay, ashes,
of fallow crops, and ploughing in green crops, to induce the
soil to yield its potash.

tSoda, as we have seen, is a constituent of many minerals,
such as albite containing 11.43 per cent., mica contain-
ing from 3 to 5 per cent., and basalt from 5 to 7 per cent, of
this alkali. But the proportion in the soil is much less, in
consequence of the action of growing plants, — many of which
take up and appropriate it as food. Common salt is a chloride
of sodium, and is found very widely diffused, so that this al-
kali exists probably in sufficient quantities in the soil to sup-
ply all the wants of plants. Its action is similar to potassa,
but it is not so essential to vegetation. Porphyritic soils con-
tain it in the greatest abundance.

Oxide of iron exists in the soil as a protoxide, peroxide
and in combination with acids. It is found in all soils, in
one or all of these forms. The use of clay has been supposed
to result from its containing from 9 to 13 per cent, of this
substance. It is also found in green sand in great abundance,
constituting about |- part of the whole mass. In fact, it is
widely diffused through all the primitive and most of the
secondary rocks.

The quantity of oxide of iron as determined by analysis,
varies considerably in different soils, from 1 to 5 per cent, in
the soils of Massachusetts. The soils of Maine contain from
2 to 12 per cent., those of Rhode Island from 2 to 8 per
cent., and generally soils contain at least 5 per cent, of this
oxide.

MINERAL CONSTITUENTS OF SOIL. 213

The protoxide of iron is generally unfavorable to vegeta-
tion, but the peroxide seems to act the part of an alkali, con-
verting the vegetable substances into the proper state to be
absorbed by the roots of plants, while the protoxide does not.
Dr. Dana says, that if" iron peroxidates itself in contact with
vegetable fhre, the texture of the vegetable fibre is weakened,
and geine is produced, and that in a few hours. It is during
the passage from protoxide to peroxide, that the 'saponifying^
action takes place, geine is produced, and then combines with
the peroxide.''^

Oxide of iron is also found in the vegetable substance, and
must be carried there in some of its combinations with acids,
as the oxide is insoluble. It probably combines for this pur-
pose, with some of the organic acids in vegetable mould,
such as crenic or humic acids, or both, and thus acts the part
of a base to those acids, which are the products of the living
principle.

Crenate of iron and of alumina are deposited in iron tanks
where river water runs. Liebig regards the oxide as perform-
ing the office of absorbing and retaining ammonia.

Oxide of manganese. But very small quantities of this ox-
ide are found in soils, and still smaller quantities in plants.
It probably acts in a manner similar to oxide of iron, forming
a base for the combination of the humic or crenic acids.

3. Salts and Urets. Under this head, are included sev-
eral compounds which analysis has detected in soils. Such
as common salt, sub-phosphate of alumina, phosphate of lime,
nitrate of potash and of soda, sulphate of lime, sulphate of
iron (copperas), sulphuret of iron, etc. Some of these sub-
stances have received attention in other places, and but a
few remarks are required to show what is most important to
be noticed respecting them.

Common salt, or chloride of sodium, constitutes about 2 J
per cent, of sea-water. It also exists in the rocks, especially
in the new red sand-stone. It seems to act as an alkali, by
, 18*

214 GEOLOGY AND CHEMISTRY OF SOILS.

furnishing soda to plants. The quantity in the soil is ex-
ceedingly small, but only small quantities are wanted. The
chlorine, which plants sometimes exhale, must come from this
substance. It is highly useful on some soils.

Sub-phosphate of alumina and phosphate of lime may be
noticed here in connection, because they have lately been
shown to be present in all fertile soils. Phosphate of lime is
the most common form in which both the lime and the phos-
phoric acid exist.

It is from these substances, that animals obtain their phos-
phorus. About 50 per cent, of bones is phosphate of lime.
Almost all the vegetable products contain it, whether the
land has been cultivated or not. It even exists in the pollen
of the pine in forests.

Nitrate of potash and nitrate of soda are sometimes de-
tected in soils.

Sulphate of iron is also detected in a few soils, and is
highly poisonous in its effects. Lime converts it into gyp-
sum and oxide of iron, thus rendering it a valuable saline
manure.

Sulphuret of iron is found in considerable quantities, but
by exposure to air and water, it changes, first to the sulphate
of iron, and then, by the action of lime, to the sulphate of
lime, as above.

Carbonic acid in a free state is also found in soils, the
quantity varying with circumstances. The action of this acid
has been fully discussed. One fact of a highly practical value
is, that the urcts are constantly becoming salts, so that the
soil is often found to contain a larger quantity of salts than the
rocks. The process of disintegration produces changes in
the arrangement of the simple elements.

Thus we have enumerated all the inorganic bodies, which
are found in the soil, as ascertained by analysis, and their
general relations to growing plants. From this examination
soils are composed, generally, of the

ORGANIC PORTIONS OF THE SOIL. 215

Earths, Mkalies,

Silica 66. per cent.

Alumina 16. "

Magnesia 1. "

Lime 2. "

Oxides,
Of Iron
Of Manganese

per cent.

Potash 2. per cent.

Soda .5 "

Ammonia .5 "

Salts and Urets, 1.5 per cent
Organic matter, 6.5 "

II. Organic constituents of the soil. A proper mixture of
organic matters with the mineral ingredients, is essential to
the fertility of the soil, and hence vegetable or animal sub-
stances are always found in soils capable of cultivation. These
organic matters are derived from the roots and other parts of
plants, or from the application of manures. The substance
which is formed by the decay of these organic products, and
which has been supposed to give fertility to the soil, is called
by several names, as humus, geine, vegetable mould, etc. and
is intended to include all the decaying organic matter of the
soil. It is a brownish or black substance, and when it be-
comes intimately mixed with the mineral ingredients, it im-
parts a black color to the soil, a greater power of absorbing
water and gaseous substances, renders it more permeable to
air and to the roots of plants, improves its texture, and in-
creases its power of absorbing and retaining heat.

This remarkable substance, a history* of which has al-
ready been given, p. 138, is composed, as we have seen,
of the following substances : Jiumin, extract of humus,
humic acid, crenic and apocrenic acids, which are generally
combined with the bases, lime, magnesia, soda or potash,
ammonia, alumina, oxide of manganese, and per-oxide of iron.
When therefore we examine the organic constituents, by anal-
ysis, we find the following substances.

1. Humic acid, which is identical in composition with hu-

* Dr. Dana, in his Muck Manual, has given a history of this sub-
stance, and advocates the use of the terra geine.

216

GEOLOGY AND CHEMISTRY OF SOILS.

min. The quantity of this acid, contained in any given por-
tion of soil, may be determined, very nearly, by the proportion
of vegetable matter, dissolved by the application of alkalies.

The following is the proportion of the soluble matter,
called soluble geine, nearly identical with humic acid, and of
insoluble geine (humin), contained in the soils of Massachu-
setts, from the different geological formations.

Soluble Geine. Insoluble Geine

Alluvium

2.25

. 2.15

Tertiary argillaceous

soils

3.94

5.22

Sandstone

((

3.28

. 2.14

Graywacke

((

3.60

. . . . 4.00

Argillaceous slate

((

5.77

. 4.53

Limestone

"

3.40

4.04

Mica slate

((

4.34

. 4.60

Talcose slate

C(

3.67

. . . . 4.60

Gneiss

((

4.30

. 3.40

Granite

((

4.05

. . . 3.87

Sienite

((

4.40

. 4.50

Porphyry

((

5.97

4.10

Greenstone

((

4.56

. 6.10

The soluble geine, of course, is not all humic acid, as other
acids and salts are dissolved by the alkalies ; still, there is not
much reason to doubt, but that there is from 1 to 3 per cent,
of this acid in all fertile soils.

2. Crenic acid was first discovered by Berzelius, in 1832,
in the water of Porla well, near Orebro, in Sweden. It exists
in all our soils, and in the waters of rivers and ponds, and is
generally associated with apocrenic acid, and combined with
bases.

Both of these acids may be precipitated from their neu-
tral solutions by means of subacetate of lead, and may be
separated from each other by the salts of copper.

It is difficult to determine the quantity of this acid. Soils,
analyzed by Berzelius, contained two per cent.

ORGANIC PORTIONS OF SOIL. 217

The crenic acid has been detected in the sub-soil, and this
may account for the utility of sub-soil ploughing. It is also
found in river water, and may account for the effects of irri-
gation. The compounds of crenic acid, described p. 136,
are also found in small quantities in the soil.

Apocrcnic acid is formed, as its name imports, from the
crenic, by simply exposing the latter to the air. It was found
in the water of Porla well, in connection with the crenic acid.
This acid is found in very small quantities ; in some soils, ac-
cording to Berzelius, about two per cent.

As all the alkalies dissolve these two acids, and as the al-
kaline earths render the inert crenates active, we can seethe
utility of adding alkaline substances to the soil to act upon
these acids, and to bring them into a fit state to enter the vege-
table organs.

" The remarks of De Saussure on soils," says Berzelius,
" seem to show, that the three constituents above described,
crenic, apocrenic and humic acids, by means of the recipro-
cal influence of water and air, become mutually changed.
Water in moist soil, changes a part of the insoluble humin
into humic acid ; so that, after a sufficient length of time, the
greater part of the humin becomes soluble. The atmosphere,
on the other hand, re-forms, from the soluble matter, humin.
Coal of humus, which in contact with the air changes a por-
tion of it into carbonic acid, is itself converted into humin
and humic acid, and this appears in fact to be the useful ef-
fect of loosening the soil by tillage which exposes it to the
influence of the air."

The extract of humus and glarin are brown matters, mostly
composed of carbon, hydrogen, and oxygen ; and, so far as
we know, are of little use to vegetation, in their pure state.
They may furnish matter for nutriment, after being acted up-
on by the air or alkalies.

Dr. C. T. Jackson states, that the substances which are
confounded under the name of soluble humus, soluble geine.

218 GEOLOGY AND CHEMISTRY OF SOILS.

etc. consist of several substances aJready referred to. Dr.
Dana calls the whole geine, and as the fertility of a soil de-
pends upon the soluble geine and salts, his method of analysis
is well adapted to determine their amount, and the conse-
quent fertility of the soil.

But whatever views are adopted, relative to the nature of
the organic constituents of soils, the fact is fully established
by experience, that a due mixture of organic, with the mine-
ral ingredients, is essential to fertility, and that the power of
the soil to bear successive crops for a series of years, depends
upon keeping up the supply of humus and salts, which a con-
tinued course of cropping takes away. Other substances
must exist also in the soil, in a state of partial decomposition,
such as the various vegetable products, but they all finally
pass into those above described, or pass off in gases, such as
ammonia, sulphureted hydrogen, and carbonic acid.

Sect. 3. Theory of the mutual action of the inorganic and
organic constituents of Soil, and of groicing Vegetables.

The different earths, acids, salts and organic matters, de-
scribed in this section, are combined in the soil with each
other in definite proportions. They are constantly subjected
to the laws of affinity, and as this power exists in different
degrees of force in the different compounds, there are frequent
and almost constant changes going forward. These changes are
aided by the influence of the atmosphere, water, temperature,
etc., and tend to alter the relative proportion of the different
compounds. The agents concerned in converting the rocks
into soils, continue to act, and the same changes continue.
These changes are those produced by the mutual action of
the organic and inorganic constituents, and those which are
produced by the agency of the living vegetable.

I. Action of the organic and inorganic elements of soil
upon each other. The elements of soil, as we have seen, are

ACTION OF THE ELEMENTS OF SOIL. 219

distributed into three classes ; silicates, that is silicic acid
united to the several bases, as in the simple minerals ; salts,
such as phosphates, carbonates, etc. ; and humus or geine,
which may include all the organic portions.

1. The silicates appear to act but slightly if at all upon each
other, and hence, were there no agent external to them, would
remain without change for ages. But the carbonic acid of
the air combines with the bases of the silicates, the potash and
soda, and forms soluble salts. These are removed by water,
and the silica and alumina remain. By this action, the soil
is rendered gradually and constantly finer, more clayey and
tenacious.

2. The earthy carbonates, such as limestone, act in the
same manner upon the silicates as carbonic acid, hence the
utility of lime to set the alkalies and oxides free.

3. The alkaline bases potash, soda, lime, magnesia and
alumina, which are thus set free, combine with the humic,
crenic and apocrenic acids, or, according to Dana, with the
geic acid and form geates, which are converted into soluble
super-geates, by the action of carbonate of lime.

4. These bases not only combine with the geic acid, but
they act by their presence or catalytic power ; and convert
insoluble into soluble geine. The power of hastening decay,
is greatest in potash and lime, next in alumina, and finally in
oxide of iron while passing from the protoxide to the peroxide,
hence the utility of these substances in rendering the vegeta-
ble matter soluble and available to the roots of plants.

5. The oxygen of the air and of the water hastens the pro-
cess of decay, and by liberating the carbonic acid, tend to
keep up the process of decomposition.

II. Mutual action of growing plants, silicates, salts and
geine. The action of salts and silicates upon each other,
even when aided by the humus of the soil, is not very rapid.
But when a living plant is introduced into the soil, it exerts a

220 GEOLOGY AND CHEMISTRY OF SOILS.

catalytic power, and causes the salts and silicates to form
themselves into new compounds. Life imparts activity to all
the chemical agents. It lets loose the bases of the salts upon
the vegetable matter, and they convert it into geine. The
liberated acids act upon the silicates and form new salts,
ready to be decomposed by the vital power, and to enter the
living organs, or to act again upon the inert silicates and in-
soluble vegetable matter,and render portions of them active.
It is in this way, that a small quantity of salt introduced into
the soil, will continue to reproduce itself, and hence the sur-
prising effects which are often witnessed, when salts in small
quantities are added to the soil.

1. The general theory then, of the action of salts, may be
thus stated : The bases of salts, whether alkali, alkaline
earth, or metallic oxide, act exactly alike '^ that is, (1) They
act continually upon the organic matter of the soil, render-
ing it soluble and capable of entering the organs of plants.
(2) They are taken into the plant, either in combination
with their mineral acids, and decomposed by the organic
acids, or eliminated directly by the vital force and assimilated.
In the latter case, the acid of the salt acts upon silicates as
above, and reproduces the same salt.

2. It will be seen, that if the salt is a carbonate, the car-
bonic acid will act with great power upon the silicates. If it
is a phosphate or nitrate, both the acid and the alkali are
nourishers, and the effect will be much increased. But if the
salt is a sulphate, or a hydrochlorate, then the acid will not
produce so good effects, and may be poisonous and highly in-
jurious, hence the character of the acid determines the char-
acter of the effect, or, as it has been expressed, peculiarity of
action depends upon the acid and not upon the base of the
salt. This is substantially the theory of Dr. Dana. It throws
more light on the action of salts, than any which we have
seen. It will be further illustrated on the subject of manures.

CAUSES OF FERTILITY.

221

Sect. 4. arcumstances upon which the Fertility of Soil
depends.

Having in a previous section, given the mode of analysis,
by which the substances which have been described are ob-
tained, this section will be devoted to an examination of soils^
with a view of ascertaining, if possible, the reason or source
of their fertility. This will enable us to understand those
various methods of improvement which will be hereafter
described.

In order therefore, to give ?i practical value to the various
topics treated of in this chapter, it will be necessary to make
some calculations, as to the absolute quantity of the various
ingredients in the soil, that we may infer what the soil re-
quires, as a condition of fertility. The first example which
we will introduce for this purpose, is the analysis by Berze-
lius of two soils, from Russia and Siberia.

A, soil never cultivated. B, long cultivated, and said to
be in an exhausted condition. C, sub-soil of the field B.

f Sand, .
Silica, ,
Alumina,
Perox. of iron,
Aluminous matter, <[ Carbonate of lime
Magnesia,
Water,

Phosphoric acid,
^ Crenic acid,
Acids combined f Apocrenic acid,
with peroxide ofJ ^^^ic acid,
iron & alumina, f^^tract of humus,
Humin and rootlets.

A.

1 B.

51.84

53.38

17.80

17.76

8.90

8.40

5.47

5.66

.87

.93

0

.77

4.08

3.75

.46

.46

2.12

1.67

^

1.77

2.34

1.77

.76

•t

3.10

2.20

ts.

1.66

1.66

52.77
18.65

8.85
5.33
1.13

.67
4.04

.46
2.56
1.87
1.87

.00
1.66

I 99.84 I 99.86 | 99.86
It will be seen by inspection of these soils, that they do not
differ m the quamity of silica, alumina and oxide of iron.
The difference in fertility, therefore, is not due to these in-
gredients. Let us examine further, and see if we can dis-
cover the true cause of it.

19

222 GEOLOGY AND CHEMISTRY OF SOILS.

The soil A, which has never been cultivated and which
was the most fertile, has the greatest quantity of crenic and
humic acids, but the soil B, which has bfeen exhausted, con-
tains less than 1 per cent., although it contains a greater
quantity of apocrenic acid than either. This acid, however,
and its salts are supposed to exert but little influence in vege-
tation. C, the sub-soil of B, appears to have received nu-
tritious matter from the soil, and would doubtless yield a lar-
ger crop than the soil itself. Here, then, we have developed
two important facts: 1. That the fertility of a soil depends
upon the humic and crenic acids. 2. That fields long culti-
vated and almost exhausted, may be rendered fertile by sub-
soil ploughing.

It may be further seen, that lime, a substance essential to
fertility, is most abundant in the sub-soil, having been carried
down from the soil in combination with humic and crenic
acids. This is another mode by which the soil becomes de-
prived of lime and alkali.

The second example we will instance, is that of three soils
from Rhode Island, analyzed by Dr. C. T. Jackson.

The three specimens were originally of the same character.

A, soil in its natural state, that would not produce more than
10 bushels of corn to the acre, less of other grain, and no hay.

B, has been improved by ashing only, and produces I J tons
of clover. C, is in a high state of cultivation, and has pro-
duced, in a three years' rotation, 60 bushels of corn, 50 of
oats, and two tons of hay per acre.

The coarser pebbles and vegetable fibres were all taken out
by sifting the soil through a fine sieve, and 100 parts of the
fine materials were subjected to analysis.

A.

Water of absorption 1 .80

Soluble vegetable matter 2.50

Insoluble vegetable matter 2.00

Peroxide of iron 2.10

Alumina 2.10

B.

C.

2.20

1.55

1.60

4.60

2.15

1.50

2.50

2.07

2.75

1.39

CAUSES OF FERTILITY. 223

Magnesia

1.00

traces.

Phosphate and crenate of lime

1.20

traces.

Insoluble silicates

88.20

88.20

89.10

99.70 100.60 100.2]

Inspection of these soils will show the cause of the different
degrees of fertility. The soil A, which was the poorest, con-
tains of soluble vegetable matter, 2.50 per cent. The soil B,
next in fertility, contains 1.60 per cent., most of the soluble
matter having been removed by the agency of the ashes, with
the crop ; while the soil C, in the highest state of fertility,
contains 4.60 per cent, of soluble vegetable matter. This
alone is sufficient to account for their difference. In fact, in
all other respects, they are all nearly alike. Now this soluble
vegetable matter, is composed of humic and crenic acids, or
their salts, the very substances which it is generally be-
lieved are the nutritious portions of the soil. On Liebig's
theory, such a result is perfectly inexplicable.

A third example is of two soils analyzed by Prof. Hitchcock,
according to Dr. Dana's rules ; one. A, from Lazelle county,
Illinois, and never cultivated, and the other, B, from Sciota
Valley, Ohio, and cultivated 14 years without manure.

A.

B.

Soluble geine (humatos and crenates)

7.6

4.5

Insoluble geine (humin, etc.)

13.8

6.7

Sulphate of lime

18.4

2.1

Phosphate of lime

0.4

0.9

Carbonate of lime

3.3

2.8

Silicates

73.5

83.0

Water of absorption

9.5

5.3

106.1 105.3

Both of these soils are of the first quality. The quantity of
soluble geine is large, and also the amount of salts. But the
difference between that which has been cultivatefl, and that
which has not, developes one of the most important facts in

224 GEOLOGY AND CHEMISTRY OF SOILS.

the whole science of agricultural chemistry ; a fact, however,
which has constantly made its appearance in these analyses,
viz. that the quantity of soluble geine in the soil A. is nearly
double of that in the soil B, and the insoluble geine is more
than three times the quantity. What inference is more obvi-
ous or certain than this, that the cultivation of the soil re-
moves its soluble geine and favors the conversion of the in-
soluble portions into those which are soluble ; and that vege-
table matter is not added* to the soil by cultivation, but ab-
stracted from it, and unless this is supplied, the land will, in
time, become exhausted and consequently barren. Thus it is
that theoretical deductions confirm actual experience.

These results are confirmed by the analysis of the soils of
Massachusetts; and hence. Dr. Samuel L. Dana of Lowell
has proposed and advocated a theory of great practical im-
portance to the farmer, that the mineral ingredients of the
soil are of little importance, but that salts and geine (soluble
vegetable matter) are the sources of fertility in all soils. The
great object of analysis is to ascertain the condition of the
organic matters in the soil, and the means of improvement,
viz. the conversion of insoluble into soluble geine.

There are facts which show, that alkalies are equally im-
portant with geine, and the labors of Dr. Dana and Prof.
Hitchcock establish this fact beyond a doubt. Liebig at-
tributes to the alkalies and salts a less extensive, but more
direct agency, in producing fertility, than has generally been
supposed.

The amount of alkalies is given in only a few soils whose
analyses have fallen under our notice. But as the alkalies
are found in plants, and exert a powerful influence in vege-
tation, it may be interesting to make some few calculations
as to their amount, in order to see if they are in fact essential
to fertility. In making these calculations, we will give the ab-

* Unless it is in wood lands or peat meadows, in which case large
quantities of vegetable matter are derived from the atmosphere.

CAUSES OF FERTILITY. 225

solute amount of all the ingredients of an acre of soil, of a
tillage depth of six inches.

In order to show distinctly the influence of alkalies and al-
kaline earths, let us first estimate the amount, in a soil com-
posed of the same materials as the rocks, allowing the soil to
be of the same composition as our ordinary granite, f quartz,
f feldspar, and i mica.

1. Supposing a cubic foot of such soil to weigh 125 lbs., 1 acre

of tilled surface, 6 in. in depth, would weigh 1361.25 tons.

Of this there is of silex 74.84 per cent. = 1018.76 "

Alumina 12.80 « 174.23 "

Potash 7.43 u 101.82, "

Magnesia 0.99 « 13.47 u

Lime 0.37 " 5.03 «

Oxide of iron 1.93 u 26.37 "

Oxide of manganese 0.12 " 1.63 u

Fluoric acid ' ,2i « 2 85 "

2. In sienite rock, hornblende takes the place of mica, 1 acre
of tilled surface 6 in. in depth, would weigh 1361.25 tons.

Of this there is of silex 74.84 per cent. = 1018.76 "

Alumina 9.79 « ^3437 „

Potash 673 u Q2.29 «

L

ime

2.76 " 37.57

Magnesia 3.76 « 57.I8

Protoxide of iron 1.46 « I9 37

Protoxide of manganese .04 " 54 u

Fluoric acid .03 u 4q »

No allowance is made here for vegetable matter, and the spe-
cific gravity exceeds that of soils which contain it, and which
are in a finely divided state and therefore more bulky, but
the amount of potash, lime and magnesia is enormous, com-
pared with the same substances in soils which have been
cultivated. Here is 100 tons of potash on an acre of soil
or of rock six inches in depth, while in the soil of Massachu-'
setts, the fine materials, separated from the coarse pebbles
accordmg to Prof Hitchcock, contain no potash in a free
state, and probably but a small quantity in any state. What
19*

226 GEOLOGY AND CHEMISTRY OF SOILS.

becomes of this alkali 1 We know that it enters into all
vegetables, as it is found in their ashes, and with them has
been removed from the soil. It will be found that the alka-
line substajices, limejand magnesia, are also abstracted in a
similar way, and hence, as a practical deduction, soils gene-
rally need to have these alkalies added, that their fertility
may be kept up. It is rarely the case, that the potash be-
comes wholly taken from the soil, but it is locked up in the
minerals, and is not exhausted until they are all decomposed.
Liebig asserts, that the soils of Virginia, from which harvests
of wheat and tobacco were obtained for a century, became
exhausted, because their alkalies were all removed, or so
large a quantity of the free alkali, that the annual disintegra-
tion did not furnish a sufficient quantity to supply the wants
of the crop. The amount of alkalies, as estimated per Hes-
sian acre,* removed in the space of 100 years, is 1,200 lbs.
mostly of lime and potash. But generally, the soil contains
enough potash, locked up in the minerals, to answer all the
wants of vegetation. " A thousandth part of loam," says
Liebig, "mixed with the quartz, in new red sandstone, or
•with the lime in the different limestone formations, affords as
much potash to a soil only twenty inches in depth, as is suffi-
cient to supply a forest of pines, growing on it for a century.
A single cubic foot of feldspar is sufficient to supply a wood,
covering a space of 40,000 square feet, with the potash re-
quired for five years."

It would be easy to show, that our forest granitic and
gneiss soils, and even our pine plain land, contain sufficient
potash and lime for all the wants of vegetation. But they
are not in a free state, hence, although growing plants, by
galvanic force, eliminate them from the minerals, still they
are not returned to the soil because they are removed
with the crop. If the plants were all turned into the soil,

* A little less than an English acre.

CAUSES OF FERTILITY. 227

the requisite supply would be obtained. The most fertile
soils contain alkalies in a suitable state to act, both upon the
vegetable matter, and to enter the vegetable organs, and
hence alkalies, especially potash and lime, are generally ben-
eficial to the soil.

It will be seen, as a practical inference from what has been
stated, that alkalies may he added to the soil, as the quantity
needed is small. If it were required to add silica ; the task
of improving the soil would be utterly hopeless ; but a single
grain of lime or potash, in a hundred, is sufficient oftentimes
to ensure fertility, and it therefore appears, that alkalies as
well as vegetable matters are essential to a fertile soil. This
conclusion may be rendered still more evident, by the follow-
ing estimates of three fertile soils fi-om the farm of J. P.
Gushing, Esq. Watertown, Mass., in which the absolute
amount of the materials are stated, according to analysis, by
Dr. C. T. Jackson. The soil originated from granite, sie-
nite and greenstone.
Insoluble silicates per acre, A. B. C.

six inches tillage depth 664.045 tons. 597.601 tons. 669.943 tons.
Alumina
Perox. of iron and mang.

rtcJJ^, Phos. and create 'of lime
>k Soluable vegetable matter

. k Insoluble do.

'^^i Magnesia
Water

Specific gravity
Cubic foot weighs

By estinjates, like the above, it is obvious to any farmer,
that the salts and vegetable matter may be supplied to the
soil, and that the great object of improvement is to supply
them.

It has been stated, that the mineral ingredients were of
far less consequence than it was formerly supposed. This is
true, yet it must not be inferred that they are of no impor-
tance at all.

35.219

((

30.390

' 21.695 «

34.494

((

23.992

' 32.976 "

4.311

((

2.399

7.376 "

26.733

((

21.193

' 22.562 "

54.329

((

69.177

' 73.763 «

1.597

4.339 "

39.678

u

43.025

' 33.084 "

1.277

((

1.195

1.255 "

79.181 lbs.

73.438 lb

3. 79.688 lbs

228

GEOLOGY AND CHEMISTRY OF SOILS.

Prof. Hitchcock has shown by an analysis of the soils of
Massachusetts, that some of the most productive in the State
contain less vegetable matter than those more barren. Al-
though the proportion of soluble geine, compared with that
which is insoluble is very great, (as these soils are the allu-
vial deposits of the Deerfield and Connecticut rivers,) it is
chiefly the frie state of the mineral ingredients which will
account for their fertility. They must be exhausted much
sooner than other less fertile soils, and will of course require
a constant supply of vegetable matter, to keep up their fer-
tility.

A continued course of cropping improves the texture of
nearly all soils. They gradually become finer, and must be
deepened to supply the requisite quantity of decomposable
minerals.

We will close this subject, by a general summary of the
principles which have been developed, considered in their
practical relations to our soils.

1. The first general conclusion is, that it is important to
the farmer to obtain an exact knowledge of the ingredients
of his soil, in order to make the required improvement. If
a soil is not productive, analysis will show the reason, and
point out the right mode of securing fertility.

2. Although the mineral ingredients of a soil are far less
important than the humus and salts, yet it is well established,
that a soil composed wholly or ^^ of s'ilica, lime, alumina or
magnesia, is entirely barren, hence sand or clay will not sup-
port vegetation.

3. Two kinds of earth are necessary to the fertility of any
soil, viz. silica and alumina. But a soil does not attain its
highest degree of fertility, unless there are added small quan-
tities of lime, magnesia, oxide of iron and of manganese. At
least, three earths are essential to the highest state of fertility.
Plants require but a small quantity of these earths to enter in-
to their constitution, therefore the proportions may vary

CAUSES OF FERTILITY. 229

widely without any apparent effect, provided the texture be
continued the same.

4. The fineness of the earthy ingredients is more impor-
tant to fertility, than the proportions in which they exist ; be-
cause the power of the soil to absorb water, and of the roots
of plants to draw in nourishment, depend upon the fineness
of the particles ; hence it is found, that one earthy ingredient
may be substituted for another, provided the electrical char-
acter of the soil is not changed. If, however, we are sure
that a soil contains silica, alumina, lime and oxide of iron,
it may be made fertile. We are sure of all but the lime,
which exists in a small quantity in all our soils, and may be
added generally without fear of injury.

5. But the most important substances to be attended to
are vegetable matters and salts. Without these, soils are ab-
solutely barren, however well constituted in their mineral
portions.

6. Fertility depends not upon the quantity of humus, but
upon its state. The greater the quantity of soluble geine
(humates, crenates and apocrenates), other things being equal,
the greater the fertility.

7. As salts are removed by continued cropping, they must
be supplied from the rocks, or from a foreign source; hence
their utility as a manure.

8. It may be inferred, that the best constituted soil contains
the various ingredients in about the following proportions :
silica 60 parts in 100, alumina 16, lime 3, oxide of iron and
manganese 7, soluble geine 4, insoluble geine 5, potash 3,
soda 1, magnesia 1. The earthy constituents may vary, but
the salts and geine must be from 4 to 10 per cent., or the soil
will not produce a bountiful crop.

9. Finally, those substances which our soils require to en-
sure fertility, are within the reach of all our farmers, and there
is the best encouragement for all to seek them out and apply
them. No excuse can be rendered if their farms do not

230

GEOLOGY AND CHEMISTRY OF SOILS.

produce bountifully, if their own stores are not well sup-
plied with all the necessaries and comforts of life.

Sect. 5. Classification and Description of Soils.

As all soils originate from the decomposition and disinte-
gration of rocks, effected by the chemical >and mechanical
agency of air, water, and vegetation, to which small quanti-
ties of vegetable and animal matters are added, the most ob-
vious mode of classification would seem to be that derived
from the geological character of the rocks. For we should
expect that soils would resemble the rocks from which they
originated, and (with the exception of some cases of great dis-
turbance by glacial action, or running water, in which cases
several varieties of rock are mingled together), that the rock
from which the soil originated would underlay it.* The fact
too that we must look to geology, to ascertain those natural
sources of fertility, which are so abundant and desirable in
every country, renders some knowledge of this science abso-

* Dr. Dana in his Muck Manual, p. 20, has given as the third prin-
ciple of agricultural chemistry, that " the rocks have not formed the
soil which covers them." This appears to be true in a restricted and
modified sense. The soil has been moved in most cases from the rock
in place, but not alwaj'^s beyond the formation. There are many
cases, where the soil is found to have originated directly from the de-
cay of the underlaying rock. The second principle, " that rocks do
not affect the vegetation which covers them," p. 11, seems to require
a similar modification. There are many exceptions to the rule, and
the truth would be as nearly expressed if the negative were left out.
A case now occurs to me of the marked influence of the underlaying
rock. There is a small belt of land in the southern part of Vermont,
in which one ingredient is silicate of lime, and the vegetation is not
only more flourishing in this formation, but the sweet grasses as clover
are much more abundant, although the situation is high, and it is
otherwise more unfavorable than the neighboring soils, which are less
fertile. Hence, the first principle, that " there is one rock and conse-
quently one soil," appears to be opposed, not only to the general opin-
ion of writers on soils, but to direct observation.

CLASSIFICATION AND DESCRIPTION OF SOILS. 231

lutely essential to an intelligent understanding and success-
ful practice of agriculture as an art.

But as such a classification may not be intelligible to those
who are wholly ignorant of geology, the more common clas-
sification of agricultural writers is added, in which no refer-
ence is had to the geological origin, but only to the chemical
character of the soil. It will be seen that both modes corres-
pond in many important particulars, and it is hoped, that the
infinite importance of an exact knowledge of soils to the prac-
tical farmer, will be a sufficient apology for adopting a method
which must necessarily lead to some degree of repetition.
Perhaps we ought to urge this as a peculiar excellence, inas-
much as each mode will throw light upon the other, and en-
able the careful student to obtain a clearer and more com-
prehensive view of the subject, than either mode taken by it-
self.

Geological Classification and Description of Soils.

Geologists make two general divisions of the rocks :
1. Stratified, or those rocks which are found in regular lay-
ers, like the leaves of a book, and which appear to have been
deposited from a mechanical and chemical suspension in wa-
ter. 2. Unstratified, or those which have no marks of strata,
but appear, from their texture and resemblance to the lava of
volcanoes, to have once been in a fused or melted state. The
stratified rocks are divided into Aluvium, Diluvium or Drift,
Tertiary, Secondary and Primary. Each of these divisions
are variously subdivided. The chemical distinction was
pointed out page 187. Geologically, then, soils may be di-
vided into the five following classes : Alluvial, Diluvial, Ter-
tiary, Secondary and Primary soils.

I. Alluvial soils. These are of two kinds ; those formed
by rivers, and those resulting from peat-swamps, or growing
vegetables.

1. Alluvial soil of rivers consist of particles of every kind

232

GEOLOGY AND CHEMISTRY OF SOILS.

of rock, over which the stream passes. The water suspends
large quantities of matter, which, in connection with the
mineral ingredients, is composed of various vegetable sub-
stances. This is deposited at the mouths of rivers, or, when
they overflow their banks, along their margins. This soil
will be fertile or barren according to the character of the
rock over which the rivers flow. Alluvial soil is generally the
most fertile and desirable of all soils. It appears to owe its
fertility to the fine state of its particles, or to its tex-
ture, and the condition of its vegetable constituents. For it
is found, by analysis, to contain less of vegetable food than
most other soils. But when rivers pass over sandstones, it
often happens, that no vegetable matter is intermingled, and
instead of fertility, nothing being washed down but silicious
matter, we have heaps of barren sand. Most of the alluvial
soils of New England and of the Western States are fertile ;
while many along the coast of the Southern States are bar-
ren plains.

The value of alluvial soil depends upon another circum-
stance. If the sub-soil is gravelly or sandy, the water, and
with it, the manure passes down below the soil into the sub-
soil. This kind of soil is the most easily recognized of any ;
and every farmer knows it, under the name of interval or
meadow land. Its position also points it out, as it is gen-
erally found along the banks of rivers, and at their mouths.
In the latter case, the ocean waves often throw it back mix-
ed with marine exuvia upon the land, and form salt-marsh al-
luvions. The valley of the Connecticut river in New Eng-
land, presents some fine examples of river alluvium ; for ex-
ample, the meadows of Deerfield, Hadley, Northampton, etc.
But alluvial soils are much more extensive in the Middle and
Western States, especially in the vallies of the Mohawk,
Ohio, Mississippi and Missouri. In the West, it has receiv-
ed the name of bottom land.

2. Peat alluvial soils. Among the alluvial soils n)ay be

DILUVIAL OR GLACIAL SOILS. 233

ranked the pmty soils, which consist mostly of vegetable
matter, partly decayed and partly in a state of preservation.
This variety of soil is of every degree of texture and fertility.
Some of the peat meadows and swamps contain pure peat,
with a small quantity of mineral matter. In this case,
they should be regarded rather as depositories of fuel and ma-
nure. But they can be made the most valuable of all soils,
because they contain inexhaustible quantities of vegetable
food.

Peaty soils, include all those in which are found large
quantities of vegetable matter, in a partially decomposed state.
A large portion of the peaty soils are left wholly barren,
through want of chemical skill to bring them into the proper
state for producing crops.

11. Diluvial or glacial soils.* These are more extensive
than any other. They seem to have resulted from the action
of glaciers, when the position of the earth was different from
what it is at present. They are composed of sand, gravel
and rounded pebbles, which are mingled together and appear
to have been moved, in a southerly direction from the rock
out of which they were formed. In consequence of this trans-
portation of the abraded materials, by glacial or some other
action, the detritus of several kinds of rock are in some cases
commingled. In others, the materials are not carried far be-
yond the rock from which they were formed ; so that the ex-
tent of this division of soils is much less, than would other-
wise appear.

Diluvial soils may be divided into three varieties ; sandy,
gravelly and argillaceous.

1. The sandy and gravelly diluvial soils differ only in the
relative fineness of their materials. The most common varie-
ties consist of course sand, and rounded pebbles. These are

" Called glacial soils because it is now pretty well established, that
the diluvial or drift was formed by glaciers. (See Hitchcock's Report
of the Geology of Massachusetts.)

20

234 GEOLOGY AND CHEMISTRY OF SOILS.

the poorest of soils, especially when the pebbles and the sand
are mostly from quartz rock. They form, to a great extent
the silicrous soils of agricultural writers, and are generally
warm and dry, without the power of retaining the manures
which are placed upon them.

2. The other variety of the diluvial soils, the argillaceous,
are exactly similar to those in the next class. They are
formed of clay and sand, and are the opposite of the gravelly
diluvial soils in their character, being heavy, moist, retentive
of manures, and of water. They are capable, however, of
being made the most fertile and valuable of soils ; as they
compose what are generally denominated clayey, and when
long cultivated, loamy soils.

III. Tertiary soils. The tertiary rocks are alternate beds
of sand, clay and marl, generally arranged in horizontal lay-
ers, and often not hardened into solid rock. The clays or argil-
laceous earths seem to have originated from the argillaceous
minerals ; of which feldspar, mica and zeolite are the prin-
cipal. These, with the last described variety of the diluvial
soil, answer to the description of clayey soils, although soils
from the tertiary rocks include several varieties. The cagil-
laceoiis in which clay predominates, and the sandy which re-
semble the soils of the diluvium, are two important divisions.

The tertiary beds, many of them, seem to have resulted
from the filling up of ponds and lakes which were sometimes
covered with fresh, and at others, with salt water; hence,
they are often composed mostly of carbonate of lime, and
are filled with fossil remains, especially of shell fish. But
the more common variety of this soil is the clayey, and this
varies from the stiff clays in which water and manures are re-
tained for a long time, and which are generally cold, wet and
unfruitful, to i\\e richest clay loams, in which there is just sulfi-
cient alumina to give them body, and to enable them to sup-
port the roots of the grains and grasses, for which crops they
seem best fitted.

TERTIARY AND SECONDARY SOILS. 235

The sandy varieties of the tertiary soil often consist of al-
most pure sand, laying directly upon beds of clay. They
may be easily improved by deep ploughing, especially when
the clay is not more than 6 or 10 inches below the surface.
The sand and clay being mingled together, will improve the
texture. The clay often contains carbonate of lime and ox-
ide of iron ; two indispensable substances to the fertility of
any soil. But as most of the tertiary soils resemble those
from other formations, they will be described under the head
o^ clayey soils.

The tertiary soil is of limited extent in New England. It
is confined mostly to the region of plastic clay. All the com-
mon clay-beds, and the soils resulting, are assigned by Prof.
Hitchcock to the diluvium.

IV. Secondary soils or soils from the secondary rocks.
The secondary formation includes a great variety of rock, and
consequently a similar variety of soil. It would be useless
here to point out all these varieties, as the chemical mode of
classification will bring many of them together, as identical
in composition, and in their agricultural relations.

1. The cretaceous or chcdky soil is rarely found in this
country, but is very abundant in England. (1) It consists of
calcareous earth in the form of chalk or marl, mingled with
flint, pebbles or concretions, and will be described under the
head calcareous soil. When this soil covers chalk rocks it
is white, and reflects the heat, hence it is often cold ; but
many varieties of it are very fertile.

(2) A second variety of the cretaceous soil consists partly
of green sand, resembling chlorite or green earth mingled
with sand. The green sand often contains large quantities of
potash, and has been used in New Jersey as a manure with
the most salutary effects. But this variety of soil, in this
country, with the exception of New Jersey, does not gene-
rally contain potash.

(3) A third variety consists of blue marl clay, carbonate

236 GEOLOGY AND CHEMISTRY OF SOILS.

of lime, with sand and fossil shells, which are derived mostly
from the gault or wealden rocks. These resemble the clayey
soils of the tertiary formation.

2. Oolitic soil is remarkable for the quantity of calcare-
ous earths which it contains. It is derived from argillaceous
limestones, clays and marls, and in consequence of the great
quantity of fossil remains, is a very fertile soil.

3. Salifcrous or sanchtone soil is derived from sandstone
rocks. It is composed of argillaceous, siliceous or calcareous
matters, often highly charged with red oxide of iron, which
gives to the soil a red appearance. It is, however, of every
shade of color, and variety of texture and composition, vary-
ing from light sandy loams to stiff marly clays. The sand-
stone soil of New England is either colored red as in the
valley of the Connecticut river, or gray. It is warm, dry and
capable of being made very fertile. The rocks from which
this soil is derived often contain gypsum and common salt, as
at Salina, New York, and on this account favor the growth of
those plants which require a large quantity of soda. Ow-
ing to its texture, it is particularly favorable to Indian corn,
and the tap-roots, beets, carrots and turnips. The magnesian
variety is much more retentive of water, and constitutes a
very fertile soil.

4. Carboniferous soil is derived from three kinds of rock.
1. Thq shales of the coal beds, consisting mostly of argilla-
ceous earth with vegetable remains and sandstones. 2. Car-
boniferous limestone, also called mountain limestone, which
is so filled with the remains of small animals, Enchrinites, as
to receive the name of enchrinal limestone. 3. The old red
sandstone, which does not differ essentially from the red sand-
stone of the preceeding class. The soil will of course vary
with the kind of rock.

5. Silurian or grat/iaackc soil oug\n:ites from an extensive
class of rocks, under the name of graywacke, graywacke
slate and shale. It is composed of sand, clay and calcare-

PRIMARY SOILS. 237

ous matter. The following are the principal varieties of this
soil.

( 1 ) The conglomerate soil, consisting mostly of coarse sand
and pebbles which have been once cemented together, but
are now crumbled into soil. The rock is known as pudding
stone and is found in Roxbury, Dorchester, and many other
places in the eastern part of Massachusetts. It is far the
best soil found in this class.

(2) Slati/ soil, of a gray color, more retentive of moisture
and often clayey, but capable of being made very fertile.

(3) Slati/ red soil, in which the rock and the soil is of
a deep chocolate ; in other respects it does not differ from
the preceding. Sometimes these three kinds are mingled
together, and when the coarse pebbles constitute the sub-soil,
it is often subject to suffer by drought and to permit the ma-
nures to pass through, without producing much effect upon
the crop.

As the coal measures repose upon the graywacke, it of-
ten happens that the fine graywacke soil becomes mingled
with the carbonaceous clay slate, which renders the soil of a
clayey texture.

4. Claj/ slate soil. This soil is similar to the preceding,
but generally finer in texture and more argillaceous or clay-
ey. It is the oldest of the secondary soilsj and contains but
few remains of plants or animals. The carbonaceous clay
slate rocks when mixed with graywacke make a very fertile
soil. It is black, retentive of moisture, and well adapted to
grain, herdsgrass and clover.*

V. Primary soils, or soils from the primary stratijied and
unstraiijied rocks. This division includes a great variety of
soils. The most common variety in New England, are ar-
gillaceous slate, limestone, mica slate, talcose slate, gneiss,
granite, sienite and porphyry soils. The trappean varieties
form a distinct class.

* See Jackson's Report of Geology of Rhode Island, p. 127.
20*

238 GEOLOGY AND CHEMISTRY OF SOILS.

Soils from tlie primary rocks are most abundant in New
England. They are derived mostly from the decomposition
or decay of granite, gneiss, mica slate, argillaceous, talcose,
and hornblende slates. These rocks contain the ingredients
of nearly all soils ; silica, alumina, lime, magnesia, oxide of
iron and of manganese, to which may be added the alkalies,
potassa and soda. They are generally distinguished by the
minerals which they contain, and which exist either in large
or fine particles. The principal minerals are mica, feldspar
and quartz. The mica is seen in thin shining scales ; the
quartz in angular or rounded pebbles, and the feldspar in
white and earthy particles, more or less covered with oxide
of iron, or vegetable mould. These ingredients may be de-
tected by mixing the soil in water, agitating it a while, and
pouring off the finer portions.

1. Argillaceous slate soil is derived from a rock well
known from its structure, and from its use for the purpose of
roofing buildings. It exists in very great perfection in Ber-
nardstown, Mass. and Guildford, Vt. The color of this soil
resembles the slate, which is dark brown, almost black. It
is a poor soil in many places, especially where the rock ap-
proaches near the surface, but when the disintegration has
proceeded to a greater depth, it is capable of being made a
very good soil. It is composed almost entirely of argillace-
ous earth, mixed with a small quantity of silex.

2. Limestone soil. The primitive limestones which are
interstratified with the slates, give rise to a variety of soil,
which does not differ materially from the talcose and mica
slate soil, as it appears from analysis, that some of them do
not contain carbonate of lime in any considerable quantities.
This may be due to the action of crops, or to the fact that
the detritus of other rocks have been brought over them, and
constitute their principal mass.

Some varieties of this soil contain carbonate of lime, others

PRIMARY SOILS. 239

carbonate of lime and magnesia, forming the magnesian lime-
stone soil. A third variety contains feruginous limestone,
or iron combined with the lime, and the fourth variety con-
tains silex or siliceous carbonate of lime. This latter soil is
very fertile, and yields very sweet food for grazing.

The primary limestones diifer from the secondary in be-
ing less friable and in containing no organic remains.

The magnesian variety from both the secondary and primary
rocks is highly fertile, for although magnesia, in its caustic
state, appears to be injurious to vegetation, the rock itself,
when crumbled into soil, exerts no such effects ; probably
because it is already combined with carbonic acid.

The best test of a limestone soil whatever be its origin, is
any dilute acid such as the sulphuric, in which case, the car-
bonic acid will escape with effervescence or with foam, when
the soil is put into water, and the acid poured upon it.

The calcareous or limestone soil is of every degree of fer-
tility, and is best fitted for wheat, clover and the sweet gras-
ses.

3. 3Iica slate soil, like the rock, is composed mostly of mi-
ca and quartz. It is distinguished from clay slate soil, by
its lighter color, yet these two rocks frequently pass into each
other, and of course the soils are also mingled. In some
cases the mica slate passes into gneiss and argillaceous slate,
and the soil of course will partake of the character of both
rocks. This soil is found in very many places in Worcester
county, Mass. and in all the New England States, and is
generally very fertile. It contains but little feldspar, and
hence but little potash, but the mica yields a large quantity
of magnesia, which gives it an adhesive and loamy character.

4. Talcose slate soil can hardly be distinguished from the
mica slate by its color, although it is somewhat lighter. It
contains talc instead of 7nica, and these may be easily distin-
guished ; the former is non-elastic and of a soapy feel, the
latter elastic and tough.

240 GEOLOGY AND CHEMISTRY OF SOILS.

The fertility of this soil depends upon the mixture of oth-
er earths, such as clay. The argillaceous slate soil is quite
productive, but generally this soil is more sandy and less fer-
tile than that from mica slate.

5. Gneiss soil is very abundant in New England. It has a
pale yellow color, and is sandy and gravelly, indicating by
its appearance great sterility. This, however, is not always
the case ; the gneiss rocks contain large quantities of potash
in their feldspar, as well as argillaceous and siliceous sub-
stances. These minerals when reduced to the proper de-
gree of fineness make a very fertile soil. It is of two kinds,
the common and the ferruginous gneiss soil. The latter is of
a reddish color, in consequence of the peroxide of iron which
it contains.

6. Granite soil does not differ essentially from gneiss. Both
are composed of quartz, feldspar and mica, and of course
yield all the mineral materials necessary to fertility. The
granite soil differs in its texture from coarse gravel to fine
sand. Dr. Dana regards all soils as composed essentially of
" granitic sand," that is, just such materials as granite and
gneiss rocks would produce by the ordinary process of disin-
tegration. These rocks yield all the earths necessary to the
highest degree of fertility. But their degree of fertility will
depend upon their texture and the sub-soil. When they are
underlaid with clay, or hard gravel, cemented together and
made water-tight, they may be made very fertile, because they
will then retain the soluble manures ; but if the substratum is
open gravel or sand, the soil itself gravelly or sandy, they are
too easily drained of moisture, and permit the soluble ma-
nures to infiltrate or leach throuo-h them. Gneiss and granitic
soils are better for Indian corn and grass than for the smaller
grains.

7. Sienite soil differs from granite in containing horn-
blende instead of mica. Its structure is somewhat finer, and

TRAPPEAN SOILS. 241

its color darker than either of the preceding. It is also warmer
and more favorable to cultivation.

8. Hornhlcndc rock soil. Hornblende rock is composed
chiefly of hornblende and compact feldspar, with variable
portions of oxide of iron and of manganese, and the soil is
composed of similar materials. The color is generally of a
dark red-brown, of a fine texture, slightly adhesive when
pressed in the hand, but not clayey. This soil contains a
large quantity of oxide of iron, manganese and magnesia, the
latter substance supplies the place of clay ; the manganese,
from its dark color and imperfect conducting power, renders
the soil warm and highly fertile.

9. Porphyry soil is derived from the compact feldspars,
which contain from 25 to 30 per cent, of alumina. The por-
phyry rock is among the hardest, but it yields rapidly to the
agents of disintegration, and forms a very valuable soil.

VI. Trappean soils differ from the preceding by contain-
ing from 3 to 7 per cent, more of lime, magnesia and iron, and
20 per cent, less of silex.

1. Greenstone soil is often associated with porphyry. It
is of a finer material, and more fertile. The character of
these soils is often distinct, of a brown color, containing large
quantities of iron. Basaltic soil is very similar to the above,
but it is composed of augite and feldspar.

2. Trachyte soil. This is the soil from the ancient lava,
and is found around volcanoes. It contains a large quantity
of alkalies, which make it highly fertile. It is composed of
glassy feldspar, hornblende, mica, titaniferous iron, and some-
times augite.

3. Lava soil. The more recent lava, when converted in-
to soil, is often very fertile. It contains so large quantities of
alkali, such as potash, soda, etc. that for some crops, it is the
best of all soils. The two minerals, feldspar and augite, con-
stitute nearly the entire mass of this soil. As these matters

242 GEOLOGY AND CHEMISTRY OF SOILS.

are subjected to heat, there is a partial decomposition, and the
alkalies are ready to act upon the crop.

The above enumeration contains the most important varie-
ties of soil as derived from the rocks. They will be readily
recognized by the practical geologist, and it is hoped that the
farmer may derive some idea of their character and proper-
ties.

This geological classification, which is based chiefly on that
proposed by Prof Hitchcock, makes us acquainted with the
soils as they stand related to the rocks. This is always use-
ful and interesting, especially to the scientific agriculturist ;
but it is not so practical as the chemical mode of classifica-
tion. It is to be hoped that the reader will, at least, examine
this method and compare it with that which follows, that he
may, as already remarked, obtain from both what could not
be derived from either by itself.

II. Chemical Classijication and Dcsci-iption of Soils.

We regard the geological classification of soils, as pre-
senting the most enlarged view of the subject; but a more
simple and practical method is to arrange soils according to
their prevailing earths. These earths are silica, alumina,
lime and magnesia. Hence those soils in which silex niostly
predominates, are called siliceous or sandy soils. Those in
which clay is in the greater proportion, are called aluminous
or clayey soils. Those in which the carbonate of lime is the
chief ingredient, calcareous soils ; and when the lime is chalk,
chcdky soils. Magnesia, also, sometimes exists in sufficient
quantities to give a name to the soil in which it is found.
There is another class called loamy, which answers nearly to
the more fertile alluvions, but results from a long course of
cultivation, when large quantities of animal and vegetable
matters are employed. The 2)eaty soils are also sufiiciently
definite to form a distinct class. A short description of these
soils, including the characters by which they may be recog-

CHEMICAL CLASSIFICATION OF SOILS. 243

nized, their general mode of improvement, and their natural
adaptation to the various crops cultivated by the farmer, may
not be inappropriate.

1. Siliceous soils. In the silicious soils, from whatever
class of rocks they are derived, silex or silica is the predomi-
nant earth. These soils originate generally either from the
disintegration of silicious rocks, from glacial action, or from
streams and rivers which pass over sandstone rocks.

Properties. Siliceous soils are either gravelly or sandy,
or a mixture of both ; they are always of a loose texture, per-
mitting the water to pass easily through them.

They absorb but little moisture from the atmosphere, and
part with it readily, on the application of heat. Hence in
seasons of drought, they become mealy, and their vegetation
is scorched and dried up. As sandy and gravelly soils do
not generally combine with manure or vegetable matter,
which is introduced into them, they easily part with it, and
hence they have been denominated hungry soils. If the sub-
soil is gravelly or sandy, they are subject to leaching, and the
vegetable matter passes through them almost as fast as it is
rendered soluble in water.

Sandy and gravelly soils are generally warm and quick,
and from their want of adhesiveness, easily tilled. They dif-
fer from absolute barrenness to a high degree of fertility.
When wholly without cohesion in their parts, they are entirely
barren, and can only be made fertile by the admixture of
other substances. This is the case often with the coarser
gravels. When fine or sandy, and mixed with aluminous
earth, or magnesia and a suitable proportion of organic mat-
ter, they become very fertile, especially if they have a tena-
cious sub-soil.

Mode of improvement. A sandy or gravelly soil may be
improved by mixing clay or peat compost with them, so as to
increase their adhesiveness, their power of absorbing water and

244 GEOLOGY AND CHEMISTRY OF SOILS.

of retaining manure. The stones should not be all removed,
as''they aid in retaining heat and moisture.

These soils are naturally better fitted for rye, barley and
Indian corn than for wheat; but from their porous charac-
ter, they are particularly fitted for those crops which are cul-
tivated for the tubers of their roots, such as potatoes, turnips,
beets, etc. For the tuberous roots, however, they must pos-
sess somewhat the characteristics of loam. They are also
well adapted to timothy, clover and red-top.

2. Aluminous or clai/ soils are those in which clay in some
of its varieties predominates. They vary in composition.
Silica constitutes more than one half of their substance.
These soils originate generally from the tertiary beds of clay,
but are often formed by the disintegration of argillaceous
rock, and by the agency of rivers, especially near their
ttiouths, where the tides and waves throw back aluminous
matter, which is either contained in the water in a finely di-
vided state, or worn ofi" from the cliffs of clay near the shores.

Aluminous soils are stiff and heavy, generally destitute
of stones and very tenacious of water ; of which they absorb
large quantities, and yield it up with difficulty. When wet,
they have the appearance of mortar, and adhere to the plough,
when it passes through them. When dry, they break up in-
to lumps when ploughed, or contract upon the surface, leav-
ing small fissures crossing each other in various directions ;
hence, they are subject to the extremes of wet and drought.
The clay soils differ in texture according to the quantity of
other earths. A large quantity of silirrous earth renders them
less cohesive ; and if vegetable and animal substances are
added, they often become similar to loams. They are natu-
rally cold, especially when they are light colored, in which
case they are not easily heated by the sun's rays. They
are capable of uniting chemically with vegetable acids
and earths, a circumstance of great practical importance, as
it renders them very retentive of manures, so that in this re-

CHEMICAL CLASSIFICATION OF SOILS. 245

spect, they are the opposite of sandy and gravelly soils. Clay
soils are of every quality, from a dead, barren mass, to the
rich clay loams, which are some of the most fertile and pro-
fitable soils which are cultivated. Hence their fertility will
depend upon the proportion of other earths, the quantity of
animal and vegetable matter they contain, and the character
of the sub-soils. Common clay is wholly barren. Mixed with
calcareous or siliceous earth, it is nearly so; but when, in
addition, it contains large quantities of manure, it becomes
comparatively fertile, if the sub-soil is sand, or such as to
permit the water to drain oft'; but if the sub-soil is impervi-
ous to water, they are always cold, wet, and unfriendly to
those crops which require the heat of summer to bring them
to maturity.

The most fertile of these soils are the alluvial clay soils.
These are formed at the mouths of rivers, where the sea exerts
its influence upon the fine materials brought down by their
waters, as they flow over argillaceous rocks. They often be-
come mixed with animal and vegetable substances, and ap-
proach rich clay loams, of the most fertile and valuable qual-
ity. The common clay bottoms may be converted into fertile
clay loams, by cultivation.

Mode of improvement. Aluminous soils are improved by
admixture of siliceous and calcareous sand and peat muck.
This renders them more friable and more easily tilled.

Sand often forms the sub-soil, in which case sub-soil
ploughing may be resorted to, by which the sand and clay
will become incorporated. This is diflferent from trench
ploughing, in which two ploughs are used, the one to turn the
upper soil, and the other to bring up the sub-soil to the sur-
face. But in sub-soil ploughing no portion of the sub-soil is
brought to the surface, but merely loosened and pulverized.
By this process, the air and water exert a fertilizing influence
upon it, and then it is incorporated with the clay by trench
21

246 GEOLOGY AND CHEMISTRY OF SOILS.

ploughing. If the sub-soil is similar to the soil in composi-
tion, the same process may be gone through, but in addition,
the ground should be drained, to let the water pass off.

Crops. Clay soils are best adapted to wheat, timothy and
oats ; and where the bottom is dry, to potatoes and clover.
Clay loams, containing carbonate of lime, are the best wheat
soils known. This arises from the fact that they give stabil-
ity to the roots, furnish the requisite alkalies, and absorb
gaseous bodies, which are essential to that crop. They are
not fit for the tap-roots, although such crops exert a favorable
influence upon them by dividing the soil. They should be
ploughed in the fall, to be broken down and pulverized by
the frosts during the winter, especially if intended for an
early summer crop.

3. Calcareous soils contain large quantitiesof carbonate of
lime, under the varieties of chalk, marble, calcareous marl,
siliceous, ferruginous and magnesian limestones. It is not
necessary for a soil to be composed principally of this earth,
in order to render it calcareous, a smaller portion of it being
required to give the name, than of the other soils above men-
tioned. Calcareous soils originate from the disintegration of
limestone rocks, which are most abundant in the secondary
formation ; especially from the chalk or cretaceous group.
These soils are often washed some distance, and cover over
large areas. Some of them contain fossils and some (as those
from the primitive limestone) do not.

Properties. Calcareous soils are either gravelly or sandy,
depending upon the degree of comminution. They are more
adhesive and absorb more water than siliceous, and less than
aluminous soils. But the most striking property is their
power of causing the decay of vegetable matters, and of re-
taining several gaseous products for the wants of vegetation.
Calcareous soil is friable and easily tilled ; not suflering either
from drought or too great moisture, provided the sub-soil is
not too retentive of water.

CHEMICAL CLASSIFICATION OF SOILS. 247

Tests. Take a small quantity of the soil ; heat it to 300°
F. and then place it in a glass and cover it with pure water ;
drop on a few drops of hydrochloric acid ; if bubbles of gas
come up through the water it contains carbonate of lime.
The pebbles will also show of what the soil is principally com-
posed. The chalky variety is white, and reflects the heat
more than the darker varieties.

Degree of fertility. Calcareous soils when combined with
clay, with other earths and vegetable matters, are among the
most fertile soils. If combined with siliceous sand and grav-
el, they are light, loose and often unfertile ; but when com-
bined with aluminous earth, they are the richest soils in all
wheat-growing countries.

Mode of improvement. As pure calcareous sand or gravel
is too friable and loose for the support of vegetation, it may
be improved by adding clay-loam, or even pure clay ; and
sometimes sand and peat-muck, are highly valuable. Lime
tends to exhaust the humus of the soil; large quantities of
yard-dung or vegetable matter should therefore be supplied
to keep up the fertility.

Crops. Tillage crops are best adapted to calcareous soils,
such as peas, turnips, barley, clover, wheat and Indian corn.
They give a peculiar sweetness to the grass which grows
upon them, or rather favor the sweet grasses, and hence are
excellent soils for pasture lands.

4. The magnesian soils which result from serpentine rocks,
and magnesian limestones are very fertile soils, but not of
sufficient extent to be farther noticed in this place.

5. Peaty soils are composed of large quantities of vegeta-
ble matter mixed with earthy ingredients, lime, silica, alu-
mina and oxide of iron. They abound in the eastern part of
Massachusetts, and in most temperate regions of the earth.

Origin. These soils originate from growing vegetables,
such as mosses in swamps where there is so much water that
the roots, leaves and branches of trees accumulate, and are

248 GEOLOGY AND CHEMISTRY OF SOILS.

prevented from decomposition. In some cases a bed of sev-
eral feet in thickness is almost pure vegetable matter, and
becomes hardened into peat fit for fuel ; in others, the tex-
ture is loose and spongy.

Properties. The properties of peat soils vary according
to the character of the surrounding soils ; where the earthy
materials are clay they make a compact soil, retentive of wa-
ter, and capable of being made very productive ; when the
earth is silica, they are more light and spongy, and permit the
water to pass off. When mixed with calcareous matter they
are reduced to a fine black mould ; if the surrounding rocks
contain pyrites they often become acid ; if near the ocean,
they become mixed with sea-salt. They sometimes contain
bitumen. The properties therefore depend upon their tex-
ture, the earths with which they are combined, and the salts
which they contain. Analysis is the only sure means of
showing their exact composition.

Mode of improvement. Peat swamps must first be drained,
to carry off the water, which renders them soft and spongy ;
they will then become hard. Siliceous and aluminous earth
may then be spread upon them ; yard-manure and lime or
ashes will also improve their properties by decomposing the
vegetable matters. Some recommend paring the surface
and burning it ; then by scattering the ashes over the soil, all
the acid properties will be neutralized. The peat itself makes
an excellent compost manure for the uplands, and should be
carried into the barn-yard and mixed with yard and stable
manures.

Degree of Jertility. Peat soils are, or can be made very
fertile ; the want of fertility is not owing to any deficiency of
vegetable matter, but to their texture and to the want of
this matter in a soluble state, so as to nourish plants. When
this is converted into vegetable food and the texture im-
proved by draining and mixture of other earths, they are
the most profitable of all soils ; especially is this the case

CHEMICAL CLASSIFICATION OF SOILS. 249

in New England, where these lands are in too many cases
suffered to lie waste. Our peat swamps are decidedly the
most valuable of all our soils, because they contain food for
the plants of a thousand generations ; they ought rather
to be called manures than soils.

Crops. " Peat soils," says Buel, "are best calculated for oats,
potatoes, rye, turnips, carrots and Indian corn ; clover, timo-
thy, red-top and other grasses." If the swamps in the east-
ern part of Massachusetts were fitted for grass, they would
become more profitable than any other lands which are culti-
vated.

6. Alluvial soils. These have already been described,
p. 231. It is a remarkable fact, that according to the analy-
sis of Prof Hitchcock, the alluvial soils of New England, and
of the West, contain less vegetable matter than most other
soils. Their fertility, therefore, must depend upon the min-
eral ingredients being in a more finely divided state, and to
their power of converting insoluble into soluble food ; it is
hence inferred, that these soils will be soonest exhausted, un-
less supplied with vegetable and animal matters.

7. Loamy soils. Loams occupy an intermediate place be-
tween clayey and sandy soils, and originate from a constant
course of tillage, and the application of animal and vegetable
manures, for a course of years. It is the desire of our far-
mers, to bring all their soil into the state of loams.

Properties. The properties of loams are well known ;
they are less tenacious than clay, and more so than sand,
They are very friable, capable of sustaining drought or wetness
and easily ploughed at almost every season of the year. They
are the most desirable of all soils. The alluvial soils describ-
ed in the last section answer to the loams, as the materials
are fine and beautifully mingled together. They are divided
by Sinclair into four sorts : I. sandy ; 2. gravelly ; 3. clay-
ey ; and 4. peaty.

21*

250 IMPROVEMENT OF THE SOIL

CHAPTER VI.

IMPROVEMENT OF THE SOIL. .

The improvement of the soil is the great object of agricul-
tural chemistry. From a knowledge of the rocks and the
agencies which have been active in crumbling them into soil ;
from the physical and chemical character of soils, and, final-
ly, from the analysis in this country, we learn what they gene-
rally need to insure fertility. By an extensive analysis it ap-
pears that the earths exist in our soils in sufficient quantities,
with the exception perhaps of lime ; that the vegetable mat-
ters, alkalies and salts, are consumed by a continual course
of cropping, and must be constantly supplied. The mode of
improvement, then, relates principally to the application of
vegetable and animal matters, alkalies and saline compounds,
which latter includes carbonate of lime.

The agents which we have considered in the first two
chapters, such as heat, light, affinity and electricity, depend
chiefly for their efficacy upon the character of the soil. Vege-
table substances, for example, render a sandy soil more re-
tentive of water, and of caloric, as well as more compact.
They render a clayey soil less retentive of water, but warmer
and more friable and permeable by the roots of plants.

Carbonate of lime has been found an earthy ingredient of
nearly all rich soils ; and as our soils are nearly destitute of
it, they would generally be benefitted by its addition. Alka-
lies and saline compounds, such as potash, soda, ammonia,
nitre, common salt, etc. are, as we have seen, necessary for
the maturity of plants ; and, as they are exhausted by tillage,
they must be supplied, to keep up the fertility. There are
other modes of improvement, which pertain to the processes ~
of tillage, which are all important, and which constitute the
principal features of the modern system of husbandry. We

BY ADDITION OF EARTHS. 251

have already referred, p. 242, on the classification and de-
scription of soils, to several modes of amelioration. In this
chapter we design to describe at length, these and other modes
of improvement, and to explain the chemical and mechani-
cal principles upon which the various methods are based.

The following topics may fairly include all that is impor-
tant on this branch of the subject.

1. Improvement of the soil by adding earths not existing
in it, or existing in too small quantities.

1. Improvement of the soil by draining and irrigation.

2. By fallow crops and turning in green crops.

3. By rotation or interchange of crops.

4. By root culture.

5. By manures.

6. By tillage.

As the subject of manures is one of very great importance
to the farmer, and, as it is somewhat distinct from the other
modes of improvement, it will, in connection with that of til-
lage, occupy a separate chapter.

In the discussion of the above topics, it will be necessary
to repeat many principles already suggested. As an apology
for this, we simply urge the great importance to the farmer of
thoroughly understanding the application of these principles
in all their connections and relations.

Sect. 1 . Improvement of the Soil hy the Addition of Earths
not existing in it, or existing in too small quantities.

This mode of improvement was described generally in the
chemical classification of soils. A few remarks only need be
added here, particularly applicable to the soils of New Eng-
land, and, with a few exceptions, to this country.

1. Carbonate of lime.* It is hardly necessary to repeat

* There is no subject, respecting which there is a greater diversity
of opinion, among practical farmers, than that of the application of
lime. It is said by some, to burn up the vegetable matter ; while it is

252 IMPROVEMENT OF THE SOIL

here, that most of our soils are nearly destitute of lime, al-
though reposing on limestone rocks. We have no soils which
are strictly calcareous, and hence this earth may be added
without the least fear of injury, but with the certainty of ulti-
mate and permanent benefit. The quantity need not be
large ; four or five per cent, and even less will essentially im-
prove the texture of the soil, and supply the necessary earthy
ingredients, and it is in these two respects that we are now
speaking of it. Hence it should be applied, for these objects,
in the form of marl, shell or ground limestone. Quick or
slacked lime applied to the soil soon becomes converted, in
part, into carbonate, and air-slacked lime is already partially
carbonated ; but the application of lime in this form is better
suited to it as a saline manure. The effect of lime, as an
earthy ingredient, is to render cold, stiff clay soils more fria-
ble and light ; of course dryer and more easily heated by the
rays of the sun. Upon sandy soils, the effect is just the re-
verse ; and, in addition, it enables such soils to retain the
manures placed upon them, and counteracts the electro-nega-
tive character which the silicic acid or silex imparts to them.
2. Sand ox gravel. When a soil is too clayey or peaty, its
texture may be improved by the addition of sand or gravel.
Their effect upon such soils is similar to that of lime. The
sand gives to the clay a better consistency, and renders the
peat more compact. It is easy to understand how this is ;
but it has been a question of some difficulty to determine
whether sand or coarse gravel is the better form in which to
apply siliceous matter. This question is one of easy solu-
tion, provided all the circumstances are understood. If the
soil is peaty, the fine gravel will produce a more immediate
effect, and loam is better than gravel ; but coarse gravel will
be more durable, because it not only supplies the earthy in-
believed, by others, to add greatly to the fertility. When applied as
a carbonate, no ill effects can be experienced. In its caustic state, it
may prove injurious by forming with the vegetable matter an insoluble
substance, which thus removes a part of the vegetable food.

1

BY SAND AND CLAY. 253

gredients which influence the texture, but also the decom-
posable minerals, which are equally necessary for the growth
of vegetables. Loam, or fine gravel, spread directly upon
peat meadows, after they are drained, will render them fertile
at once ; provided that a small quantity of lime, ashes, or
other alkaline substance is added, to correct the acidity, and
dissolve the vegetable matter.

If the soil is clayey, coarse gravel will ultimately prove the
most valuable, for the same reason as above, and loam or fine
sand will produce a more immediate effect ; hence, the de-
cision of this question, and the practice, w^ill be one way or
the other, according to the object we have in view in making
the improvement. If a sufficient quantity/ of loam could be
added, it would undoubtedly be better than either sand or
gravel.

3. Clay. Sandy, light, peaty and calcareous soils are
often benefitted by the addition of clay. The mode of ap-
plying it (as derived from experience and confirmed by theo-
ry), is to spread it upon the soil in the fall or commencement
of winter, that the frost may break it down, and render it fit
to be intimately mingled with the soil, by the process of
ploughing and harrowing in the spring. Chaptal recommends
the practice of baking and then pulverizing, by which pro-
cess it approaches nearer to sand in its physical properties.

The utility of clay in agriculture has long been acknow-
ledged, but the manner in which it operates is yet a little
doubtful. Some things, however, are well settled. It adds
its adhesive and retentive properties to sandy and peaty soils,
and furnishes one indispensable earthy ingredient ; but its
effects are not wholly accounted for by the texture which it
imparts. We must resort to its composition. Now it has
been found that some of our clays, especially the clay marls,
contain small quantities of carbonate of lime. By adding
one earth, therefore, we actually add two, both of which are
especially important to soils of the above description ; for,

254

IMPROVEMENT OF THE SOIL

Oxide of Manganese 0.56

Lime 0.56

Magnesia .44

Sulphur and loss 3.22

where there is too much sand or silica, both clay and carbo-
nate of lime operate to equalize the electrical forces ; both
act as converters of vegetable fibre into vegetable food.

A specimen of common blue clay from Lowell, analyzed by
Prof. Hitchcock, gave

Water and organic matter 4.0

Silica 61.52

Alumina 20.50

Protoxide of iron 9.82

It will be seen by this analysis, that there is a large quan-
tity of protoxide of iron, and this explains further its influ-
ence. " Our common clays," says Dr. Dana, " contain more
or less of sulphuret of iron. The conversion of this into the
persulphate of iron, is the natural consequence of exposure ;
free sulphuric acid then results, which acts on any lime in
the soil forming sulphate of lime, or gypsum." But the most
important effect of the protoxide is that in passing into the
peroxide, it tends to induce decay in the vegetable matters,
which are in contact with it ; hence clay acts upon a soil
as an alkali, an alkaline earth, and a metallic oxide.

Finally, clay has the property of absorbing gaseous bodies,
which are useful in vegetation. Liebigr attributes to it the
power of absorbing ammonia, from which plants derive their
nitrogen. Daubeny regards this power in a soil, as an in-
dispensable condition of fertility.

As sand will improve a clayey or peaty soil, and clay a
sandy soil, it is matter of no little astonishment that New
England farmers have not resorted more frequently to this
mode of amelioration. In various parts of the country, sand
hills, peat swamps and clay beds, are so situated often, that
it would be the easiest thing in the word to transfer portions
of the one to the other, to the mutual improvement of all.
It sometimes happens, that a soil is reduced to an inipalpa-
ple powder when dry, and to a soft paste when wet, -while the
earthy and vegetable ingredients are in the right proportions
to ensure fertility. Such a state of the soil results from a

BY DRAINING. ^o5

long course of tillage, and is due to the fact that the miner-
als are all decomposed by the action of growing plants, and,
without decomposable minerals in the soil, no plants grown
upon it will come to maturity. Such lands, therefore, re-
quire gravel, sand or loam, and as in the cases above mention-
ed, the latter has been found to produce the best effect, while
theory at least would lead to the opinion that the former
would be most durable.

The general theory relative to these modes of improve-
ment is, first to improve the texture and consistency and
equalize the electrical state of the soil, and secondly to fur-
nish those decomposable minerals which plants must have
in order to mature their seeds.

There is a limit, however, to these methods, while time
and expense are required to carry out a system sufficiently
rigorous to produce the highest effect; but if the farmer will
have patience, coupled with perseverance, he may have the
satisfaction of seeing his soils gradually but surely approach-
ing to the best possible texture, and to the most favorable pro-
portions of all the mineral ingredients.

Sect. 2. Improvement of the Soil hy Draining and Irri-
gation.
Wet soils originate from two causes. 1. When the water,
which falls upon the surface, is retained by a retentive sub-
soil, as is often the case with level lands on clay bottoms. 2.
When the water, which passes beneath the surface along the
water-hearing strata, meets with dikes, or strata, which have
been broken off, and incline in different directions. In the
latter case, if the land is much inclined, there will be springs
formed at the out-cropping of these strata, and, if the surface
is level, the pressure of the water, from the surrounding high
lands, will force it up to the surface, and produce a swamp,
or too great a degree of moisture. In both cases the soil is
rendered cold and unfruitful, hence fertility can be restored
only by removing the cause of barrenness.

256 IMPROVEMENT OF THE SOIL

I. Draining. This mode of amendment can be applied
only to stiff clays and swamps, or to lands which have a hard
and retentive sub-soil, so that the water, in the ordinary
course of things, will not pass off, and leave the land com-
paratively dry, for a considerable portion of the season.

The operations of draining are therefore confined to sur-
face draining, draining the soil, and draining the sub-soil.

1. Draining the surface. In stiff clay soils, if the land is
level or moderately inclined, the water from rains and snows
is liable to remain on the surface, forming pools in every lit-
tle hollow. This prevents the seeds, if sown, from sprout-
ing, and injures the crop. When this water is evaporated,
the' surface becomes hard and impenetrable by air and heat,

and by the roots of vegetables.

Fig. 14.
This evil is some- au

timeseffectuallyre- mMT'^^^^^^mZ^^^^
medied by simply

throwing the land into ridges (Fig. U) by a process called
back furrowing, a process which every farmer knows well
how to perform. It will be seen by inspection of this figure,
that the water as it falls upon the crown of the ridge h h will
pass off down both sides in the same way that it does when
it falls upon the roof of a house, and either settle into the
sub-soil, if porous, or into the furrows a c between the ridges.

If the soil has an uneven surface and the water accumu-
lates in the hollows, an open drain is the only effectual re-
medy.

But in cases where the surface is level and the sub-soil
hard and retentive, resort must be had,

2. To draining the soil This is effected by penetrating the
sub-soil so as to form a passage for the water to pass off from
the field, or a reservoir into which it may ooze from the sod.

The drains by which this is effected may be either open
or covered. The latter, or underground drains, are the

BY DRAINING. CONSTRUCTION OF DRAINS.

257

cheapest, most durable and most effectual ; for, aside from their
convenience, a considerable quantity of land is saved for cul-
tivation.

(Fig. 15.)

Before constructing a drain for this purpose, it is neces-
sary to examine the land, and ascertain where the springs
are. Most cases of surface-draining refer to swamps, or
low lands. Suppose BOD (Fig. 15) is a swamp, or low
ground in which the water collects, either from the high
lands, or from springs in the margin B D, or anywhere in
the centre of the meadow. The first thing to be done, in
this case, is to make an outlet for conducting the water away
to some stream as at O S. The second is to run a drain
through the centre from Cto O, and all around the margin
B D, to cut off the springs, and to conduct the water into the
main drain A, or outlet. In each case these drains should
be sunk into the sub-soil, and if much water flow in them
they should be open, especially the central drain. In this
way the swamp can be rendered perfectly dry and capable of
being cultivated.

Construction of under-ground drains. Under-ground
drains should be from two to three feet in depth, in order
22

258 LMPROVEMENT OF THE SOIL

that they may not be injured by the tread of cattle, and the
heavy loads, which may pass over them. The sides should
be a little flaring, that is, the drain should be a few inches
wider at the top than at the bottom.

Fig. 16.

The materials used for filling up the lower
portion of the drain, may be small stones, tiles
or any hard substances. 1. If no water of con-
sequence is to flow in them, they may be filled
up, with these small stones, to the depth of
from ten to fifteen inches, and the remainder
filled up with gravel and loam. 2. But in
case water is expected to flow in them, a con-
duit must be laid on the bottom (Fig. 16.)
This is made by building a wall, on each side
with stone or brick, about six or eight inches
in height and six in width, and covering it over
with flat stones so tight that mice or moles
through it, and let in the soil from above and choak it up.
If the earth is soft, the bottom also should be lined with
stones. Upon the top of the flat stones, and upon the sides,
fill in small stones c to the height of several inches according
to the depth of the drain, and then cover the whole with
earth a b, rounding the surface, so that when the whole set-
tles, it may be even with the ground.

The conduit, in case stones cannot be found, may be
made of tiles from clay, resembling earthen ware. These
are laid together and form a complete tube for conducting
away the water.

In some cases the surface may be drained by digging deep
pits and filling them with stone. This mode is adopted when
the sub-soil is hard or clayey, and a few inches below, are stra-
ta of sand or gravel. By digging through the retentive sub-
soil, the surface-water will run off".

3. Draining the sub-suil. This process becomes necessary

BY DRAINING THE SUB-SOIL.

259

in consequence of the inclination of the strata or layers of
clay and rock near the surface. The sub-soil is often thus
constituted, and these incline to the surface, or crop out upon
the sides of hills. The water-bearing strata which lies below
the sub-soil being brought to the surface, produce springs
which are a fruitful source of wet soils.

The water in some cases rises up through the sub-soil by
the force of pressure from the neighboring highlands, and
produces a swamp.

In case of sub-soil draining, the object is to intercept the
water below the surface by cutting through to the water-
bearing stratum, and forming a conduit for it to pass off. This
is the most difficult part of draining operations.

(Firr. 17.)

In order to show the nature of the difficulty, and the most
common methods of remedying it, let us suppose that Fig. 17
is a section of a piece of land : a the high land, d a swamp,
which may be produced by one or all of the water-bearing
strata a g h, which crop out at b c, and produce wetness
along the surface below. The water in A, meeting with the rock
f, rises up at e d. The land from 6 to c may be drained
by a ditch at b, conducting away the water at the point
where it reaches the surface. The land between c and d
may be drained by the ditch c. But as the water-bearing

260 , IMPROVEMENT OF THE SOIL.

Stratum h meets with resistance at f, open drains must be
sunk at d and c, to conduct it off into some stream, in or-
der to deprive the whole of superabundant water. It is not
often that more than one water-bearing stratum crops out,
and the most important point is to determine the cause of
the wetness, in order to save time and expense in conducting
it off.

Necessity of draining. The necessity and importance of
draining wet grounds, may be rendered evident by the fol-
lowing considerations.

1. An excess of water or moisture prevents the ploughing
and pulverizing of the soil until late in the season, and when
the attempt is finally made, it can but imperfectly succeed ;
hence the manures, not being properly incorporated with the
soil, are deprived of their effect upon the roots. The crop is
checked and is liable to be injured by early frosts.

2. An excess of moisture prevents the process of decay, or
the decomposition of the organic matters in the soil, and thus
cuts off a regular supply of food. This effect is exemplified
in peat-swamps, where the vegetable matters being prevented
from decay by water, accumulate in large quantities, to the
depth often of 20 feet, and form peat.

3. Lands which have an excess of water, often become dry
and compact in seasons of drought. The roots are thus not
only prevented from penetrating the soil and from extending
themselves freely in all directions, but the influence of the
air, and of the dew, which are so important in dry weather,
are almost wholly excluded from them. Hence such soils,
especially if they are stiff clays, suffer as much from drought
as from excess of moisture.

4. When the roots of plants extend into a wet soil, the
food is too much diluted, or is not prepared in sufficient
quantities to ensure a healthful and vigorous growth. Leaves
and ill-formed shoots will sometimes be abundant, instead of
flowers and fruit. There are a iew plants which will flourish

REASONS FOR DRAINING. 261

well in a wet soil, but not one in ten of those cultivated by
the farmer. The following table shows the proportion of
useless and useful plants on different soils. Whole number
of plants are, in

Wet meadows

30,

useful 4,

useless 26.

Dry meadows

38,

1 " ^,

" 30.

Moist meadovv's

42,

" 17,

« 25.

5. An excess of water injures and destroys the fibrous por-
tions of the roots, or spongelets, by means of which nourish-
ment is received. This effect takes place always when the
water becomes stagnant and putrescent, as it is liable to be-
come, when the land is level and the sub-soil retentive. In
some cases the tissue is decomposed, and the joints of the
stem separated. In others, the plant rots ofT at the ground,
especially if there is little light and heat.

6. An excess of water excludes the influence of heat and
air, two indispensable agents to the growth of plants. De
Condolle regards the influence of stagnant water about the
neck of plants, as operating simply to exclude the oxygen of
the air ; but Lindley more properly attributes the injury to
the low temperature of the soil, in which water is suffered to
accumulate.

7. Experience shows that however well a soil may be con-
stituted in its mineral ingredients, and however rich it may
be in humus or geine and salts, no cultivated crop will flour-
ish well unless the surface of the soil, and the soil itself is
made dry during the growth of the crop, and when required
to be worked by the plough or the hoe.

"It is because of the danger," says Lindley, "of allowing
any accumulation of water about the roots of plants, that
drainage is so very important. In very bibulous soils this
contrivance is unnecessary ; but in all those which are tena-
cious, or which, from their low situation, do not permit su-
22*

26'2 IMPROVEMENT OF THE SOIL

perfluous water to filter away freely, such a precaution is in-
dispensable." Hence the

Utility of draining must be evident to every farmer. For
a system of draining, rightly conducted, will not only remedy
the evils above described, but will save much time and labor
in the cultivation of the crop ; two weeks, at least, will be
gained in the getting in and ripening of it. The product
will be one third greater, and one third of the labor saved
in the tillage. " An outlay of 15 or 20 dollars per acre,"
says Judge Buel, " has often repaid, by extra product of the
reclaimed land, in two or three seasons." In addition to
these advantages, large portions of barren land, in many
(portions of the country, may, by this method, be reclaimed
;and rendered productive. We know, from actual observa-
tion, that some of the most valuable lands in Massachusetts,
now lie entirely waste, in the form of peat-meadows and
•swamps, to the cultivation of which it is for the highest inter-
est of every farmer to devote his immediate efforts.

II. Irrigation. Water, as we have seen p. 93, is essen-
tial to the growth of plants, both because it furnishes them
food, and because it is the vehicle through which soluble
matters are conveyed into the vegetable organs.

We know that plants will not flourish in a soil which is
saturated with water ; and we also know, on the other hand,
that when the soil, without being chemically dry, contains so
little moisture as to appear dry, vegetables will wither and
die. The question to decide is, what amount is most con-
genial to the same species at different periods of their growth ?

1. It may be taken as a general rule, that the proper time
to water, is when the soil is deprived of moisture to such a
depth, that the plants begin to languish and lose their leaves.
The juices then become thickened, and the transpiration is
nearly suspended ; hence the plant will hasten to perfect its
ilowers and fruit, which will be incomplete and poor. The

BY IRRIGATION. 263

effect of water, at such a period, is to dilute the sap and to
furnish the means of transpiration ; for all the excess of wa-
ter, taken up by the roots, is thrown off by the leaves.
Hence the quantity transpired depends upon that imbibed.

2. During the rest of plants in the winter of northern cli-
mates, and the dry season under the tropics, but a small
quantity of water is required, because the plants do not trans-
pire it. Excess of moisture at such seasons, often distends
the vessels and exposes them to injury by the frosts of spring.
No more water should be supplied than is taken up by the
capillary attraction of the soil.

3. It is during the growth of plants, and when their leaves
are fully matured, that the greatest quantity of water is re-
quired. The young leaf tranpsires much more in proportion
to its surface than when fully matured, and hence requires a
greater quantity to be absorbed by the roots ; but when the
leaves grow old, their cuticle hardens, and the apertures
through which the water passes off, gradually become closed
up ; hence, water should be supplied to plants abundantly
when they first begin to grow, and should be diminished as
they grow older. During the ripening of the succulent fruit,
plants require the least quantity ; and if a large amount is
supplied at that season, the fruit may be plumper, but will
loose much in quality. Strawberries niay be increased in
size, by flooding their beds with water during the period of
ripening, but they lose their flavor, and become insipid.

It will be perceived, that this mode of improvement is of
limited extent unless in case of green houses and gardens. It
is applicable chiefly to light sandy soils. Heavy argillaceous
soils are never benefited by it. When dry soils are situated
in the vicinity of streams or Artesian wells, water may be
^ brought on to them with highly beneficial effects. The char-
acter of the water for irrigation upon dry lands, is a point of
considerable importance. Water from a running stream is
vastly superior to that from wells or springs, and the farther

264

IMPROVEMENT OF THE SOIL.

the water has run, before it reaches the place where it is
taken on to the land, the more remarkable its effects. This
is due to two causes ; 1. It obtains a larger quantity of gas-
seous bodies such as oxygen and ammonia ; and 2. it has been
shown, that water from streams contains crenic and apocrenic
acids often combined with silica, and also other salts, which
it has dissolved out of the soil or rocks, as it has passed over
them.

(1) The first effect of water, when made to flow over the
soil by this process, is to soften it and render it more permea-
ble to the roots of plants, and to the air.

(2) Water acts still further in dissolving out the food, and
producing those chemical changes which must take place in
the manures, before they are fitted for nourishment.

Care should be taken, not to apply water so often as to
keep the soil in a state of paste, in which case, the plant may
increase in size, but the products will be loose and spongy in
texture, and vapid in taste. There is danger too, of favoring
the growth of rushes and other wild grasses, which will take
the place of the more valuable ones.

Another caution should be given on this subject, particu-
larly applicable to garden plants ; upon which surface- water-
ing is sometimes practised during the dry season. The effect
of thus pouring water around plants, especially in the heat of
the day, is to render the soil compact and heavy ; thus pro-
ducing the very evil which it is intended to remedy. It ex-
cludes the air and the water which it contains from the roots.
If surface-irrigation is ever practised on garden vegetables, it
should be done at night.

Meadows seem to be most benefited by irrigation in our
climate, although we know that in some countries as Egypt,
it is practised upon all kinds of soil, and for every species of f
crop. In the vicinity of Liegen (Germany), according to
Liebig, from three to five perfect crops of hay are annually
produced upon the same meadow, by covering the fields with

FALLOW CROPS AND NAKED FALLOWS. ^65

river water in the spring. **This is found to be of such ad-
vantage, that supposing a meadow, not so treated, to yield
1,000 lbs of hay, then from one thus ivatered, 4,500 lbs are
produced," an increase of more than 400 per cent.

The practice of inundating meadows during the winter, is
recommended both by Chaptal and Davy. The latter found
that when the thermometer stood at 29° F. above the ice, it
was 43° below it ; hence, the roots of grasses are kept from
fi"eezing, and the whole plant remains in a green and vigor-
ous state during the cold season. This practice, in this coun-
try, is too much confined to peat meadows, where the object
is not to defend the herbage, but to prevent the frost from
rendering the peat light and spongy.

Sect. 3. Improvement of the Soil hy Fallow Crops, and hy
turning in Green Crops,

I. Fallow crops. " The fallow time," says Liebig, " is that
period of culture during which land is exposed to a progres-
sive disintegration by means of the influence of the atmos-
phere, for the purpose of rendering a certain quantity of alka-
lies capable of being appropriated by plants."

By " fallow crops " is meant the raising of some crop on
green-sward while the turf is decaying, instead of allowing
the land to remain a naked fallow during this process.

The object then of fallows, is to procure the decay of vege-
table matters, and the abstraction of alkalies from the mineral
portions of the soil.

Naked fallows accomplish both of these objects, and have
been long practised both in this country and in England.
The practice with us has been to plough up grass lands in
June or July, and after cross-ploughing and harrowing, to
sow with winter grain in September or October. In Eng-
land, the land was formerly ploughed in the fall, and worked
over during the following summer. In both cases one crop
is lost ; but, though naked fallows answer the intended pur-

266 IMPROVEMENT OF THE SOIL.

pose tolerably well, they are now abandoned by every intelli-
gent farmer on both sides of the water ; with the exception
perhaps of wet stiff clays, which are ameliorated by exposing
the naked furrows to the frosts of winter. The evils of the
system are more than equivalent to the benefits. The labor
is much increased, one crop is lost, and the vegetable matters
are dissipated, by their exposure to the air during the pro-
cess of working the land.

Fallow crops, on the other hand, avoid these evils, and se-
cure greater benefit both to the soil and the crop.

Process. To prepare the soil for a fallow crop, all that is
needed is to plough the green-sward and roll it down ; then,
after harrowing thoroughly, the seed should be sown upon
the inverted furrows, either in the spring or fall. If the land
is stiff and wet, the autumn is preferable ; if light and dry,
the spring is the best season.

The utility of fallow crops, instead of naked fallows, may
be shown by reference to the influence of growing vegetables
upon the soil. The elimination of alkalies and decay of
vegetable matter are, as we have said, the only objects of
fallows.

It may easily be shown, that both of these ends are much
belter attained by tilling the fallow land ; for,

1. The alkalies are furnished in greater abundance by this
process. It matters not whether the land is covered by woods,
or with some crop which will take up but few alkalies, such
as potash and phosphates. Now it is found that several legu-
minous plants will grow upon a soil, and will abstract from it
but a minute portion of alkalies. The " Windsor bean {vi-
ciafaba) contains no free alkalies, and only one per cent, of
the phosphates of lime and magnesia." [Ein/iof.) " The
kidney bean (phaseolus vulgaris) ^coni^ms only traces of salts."
(Braconnot.) " The stem of lucern (mcdicago sativa) con-
tains only 0.83 per cent., that of the lentil (crvnni lens) only
0.57 of phosphate of lime with albumen." (Cromc.)

UTILITY OF FALLOW CROPS. 267

''Buckwheat, dried in the sun, yields only 0.681 per cent,
of ashes, of which 0.09 parts are soluble salts" [Lichig) ;
hence, these plants with others, have been called fallow crops.
It will be perceived, that the alkalies which the oxygen and
carbonic acid of the air are eliminating from the soil, will be
increased in this case, because the roots of the crop will per-
mit these agents to act with greater power.

The power of growing plants to decompose the rocks, and
to eliminate alkalies, has already been frequently referred to :
and as but a small quantity of alkali is removed by the fallow
crop, the amount in the soil is, upon the whole, increased.

2. It is further evident, that the roots leave in the soil nearly
as much vegetable matter, as is carried away in the stalks and
grain. This deficiency is made up by the influence of grow-
ing plants upon the humus of the soil. There is little doubt,
but that decay proceeds much more rapidly when the soil is
tilled, than when it is not ; and the reason is, the galvanic
agency of the roots and the facility which they offer for the
introduction of air and water by loosening the soil, tend pow-
erfully to hasten the decay of humus, or to convert the vege-
table matters into vegetable food. The fermentation of the
sod will be more complete when it is turned in deep, and the
gaseous products will be retained by the superincumbent
earth ; hence we may draw an argument for deep ploughing,
and for letting the sod remain until it has completely passed
through the fermenting process.

II. Turning in green crops. The turning in of green
crops, has long been a reputed source of rendering barren
soils fertile. It is well suited to any soil which requires either
to be rendered lighter, or to be filled with veoretable matter
and salts. Light sandy soils, such as pine-barrens and loams,
which have been exhausted by a long course of cropping
without manuring, are most benefited, while stiff clays are
rendered much warmer, and more friable.

Processes. 1. Green crops may be sown for the purpose

268 IMPROVEMENT OF THE SOIL.

and turned in, either before the seed ripens (in which case two
crops may be turned in the same season), or after the crop is
nearly ripe. In the first case, before the ripening of the
seed, the plant derives most of its substance from the atmos-
phere ; but when the seeds are maturing, it draws directly
upon the matters in the soil. Some experiments have been
made to decide which course is best, and they incline to the
dry crop. If but one crop is to be added to the soil, this
would be the best process, because it adds a greater amount
of salts and humus ; but two green crops are better than one
dry crop. Buckwheat and oats answer well for this purpose.
2. But the better course is to save the crop by sowing clover
with other grain, and the next spring turn it in ; and, having
rolled it down, plant directly upon the furrows with potatoes
and corn. The surface, then, should be tilled with the cul-
tivator or hoe, so as not to disturb the sod. Some recom-
mend, in this case, to spread a light covering of compost-
manure, lest the soil should be too much exhausted by the
crop.

Now it is found that the quantity of vegetable matters
added to the soil by this process, will exceed 12 tons to the
acre. Elias Phinney, Esq. of Lexington, has actually weighed
the vegetable matter in a cubic foot o^ green sod, from which
he made an estimate that one acre contained more than 13
tons !

The best thne for turning in green crops, or breaking up
green-sward (unless the soil is a stiff clay), is the spring and
early part of summer; because the sod will become rotted
before winter, and will not afford, as it otherwise might, a
shelter for worms, during that season, ready to injure the
succeeding crop.

Theory. The theory of this process is exceedingly simple.
It is evident that what is taken from the soil must be returned
to it, or the land will be impoverished. We have seen that

TURNING IN OF GREEN CROPS. 269

salts and geine are removed. This process simply restores
them.

1. The green crop being buried deeply in the ground,
soon begins to ferment and decay ; a large quantity of or-
ganic food is thus added to the soil. But humus or geine is
not the only substance required by plants. They must have
alkalies.

2. These are supplied in part by the influence of the at-
mosphere, the ordinary process of disintegration. But this
is trifling compared with

3. The galvanic effect of the living plant. The agency of
growing plants has hitherto been overlooked in this connec-
tion. As the roots form a galvanic battery with the soil, they
become the most powerful decomposing agents. Now we
know that the poorest soils (the pine-barrens) contain a large
quantity of alkalies, potash, lime, etc. locked up in the rocks.
These are drawn into the organs of plants, where, as soon as
covered with earth, they exist in a fit state to nourish future
crops. If, then, we can make a plant grow at all upon such
soils, we can render them fertile by turning in green crops,
and thus furnishing the requisite amount of geine, alkalies
and salts. If the soil is too barren to produce plants, a small
coating of ashes will give a start to the green crop, and then
the soil may soon be rendered fertile.

In case of clayey soils, the turning in of green crops not
only restores what is exhausted by tillage, but renders the
texture much better fitted for the roots of plants, and the soil
itself a better retainer of heat.

In case of dry, gravelly soils, the additional vegetable mat-
ter gives the power of absorbing moisture and equalizing the
heat ; hence, it protects the plant from the extremes of dry
and wet seasons.

The importance of this mode of improvement is not fully
felt by our farmers. By sowing a few pounds of clover-seed
with his grain-crops, the farmer may be constantly augment-
23

270 IMPROVEMENT OF THE SOIL.

ing the fertility of his soil without the loss of a single crop ;
and even if his lands rest a year, and all their produce is
given back to them, they will more than return it in a few
years, by the larger quantity and better quality of their pro-
ductions.

It will be seen that fallow crops and the turning in of
green crops, are somewhat similar in their influence upon the
soil. The object in both cases is to obtain alkalies or salts
and geine. Fallow crops yield mostly the former, green
crops principally the latter ; and by both processes taken to-
gether, a soil may be rendered very fertile, without the addi-
tion of manures; especially for crops not requiring much
nitrogen.

Sect. 4. Rotation or Interchange of Crops.

Rotation of crops is to cultivate, successively, on the same
field, crops of different kinds and of different habits, such as
common grains, roots and grasses.

The necessity and utility of an interchange of crops has
been ascertained by experience.

1. It was found that the growth of annual plants was ren-
dered imperfect, by cultivating them on the same soil in suc-
cessive years; and that a greater quantity of grain would be
obtained to let it rest for a season, during which time it
seemed to regain its original fertility.

2. It was also observed that some plants, such as peas,
flax and clover, do not thrive well on the same soil until after
several years ; whilst others, such as tobacco, rye, oats and
Indian corn, may be cultivated in close succession.

3. It was further ascertained by experience, that one class
of plants improve the soil, a second impoverish it, while a
third class exhaust it.

4. To keep up the fertility, manure has always been em-
ployed. But however much a soil may be manured, it is

REASONS FOR INTERCHANGE OF CROPS. 271

well established, that the produce of many plants diminishes,
when cultivated for several years on the same soil.

5. But on the other hand, it is also fully settled, that when
a field has become unfitted for one species of grain, it is not
therefore unfitted for another ; but that a succession of plants
will flourish well without the addition of a large quantity of
manure; hence has arisen the modern system of rotation.
It now becomes a question of the first importance whether
these facts can be so explained, as to aid us in pointing out
the best system of rotation. If we can fully ascertain the
causes of the failure of the successive cultivation of the same
crop, and of the favorable effects of rotation, we shall be pro-
vided with the best hints for constructing a proper system.
These causes are to be found in the structure of plants, in
their composition, and in the influence of the matters which
they excrete by their roots.

I. The structure of plants, such as their roots, stalks and
leaves, afford one important reason for the rotation of crops.
Each family of plants have similar roots, leaves, etc. Their
action upon the soil is therefore similar. The spindle roots,
for example, like the carrot and beet, extend their roots deeply
into the soil, while the common grains lie near the surface.
Clover and some of the grasses penetrate to a considerable
depth, and branch out in all directions ; hence, when one kind
of crop is planted in the same soil for several successive
years, the effect both mechanically and chemically is the
same. Chaptal supposes that the roots exhaust only those
portions of the soil which are in contact with them,
and hence similar roots exhaust the soil in the same parts;
but this effect could not take place when the land is ploughed
between each crop, though it might apply to trees. This
theory is wholly set aside by the fact, that the roots form a
galvanic battery with the soil ; and, as in all galvanic circles,
the matter would be transferred from some distance around,
so that the plant could stand in no need of food, provided it

272 IxMPROVEMENT OF THE SOIL.

were surrounded by substances, which will keep up with it,
the vigor of the galvanic action.

In addition to the mechanical effect upon the soil, we
would suggest whether similar roots may not form with the
soil similar galvanic circles of similar power and mode of ac-
tion, and that the interchange of crops changes this action or
restores its activity. We know that different metals require
different substances to excite the voltaic currents, and that
rest or a change of materials will restore the action of a bat-
tery, when its power is exhausted. The reason why some
plants exhaust the soil more than others, is partly due to their
structure. In this respect plants are divided into three classes.

1. The culmiferous plants, so called from culm, the stalk,
which is usually hollow and jointed in order to afford support
both to the leaves and seeds. Wheat, barley, oats, rye, In-
dian corn, tobacco, cotton, flax, hemp and the grasses, are
of this class. All of them, save some of the grasses, are
termed exhausters of the soil, and in all cases exhaust it
more during the ripening of the seeds than during any other
period of their growth. Flax and hemp are the most ex-
hausting crops, because their leaves are small, and hence but
a small quantity of their substance can be obtained from the
atmosphere. They also return but a small quantity of mat-
ter to the soil, in the form of stubble and roots.

The smaller grains rank next in their power of exhausting
the soil, because their leaves are narrow and roots small.
They, however, return more to the soil in the form of stubble.

Indian corn, tobacco and rice, have larger leaves, and de-
rive more of their substance from the atmosphere. The roots
of culmiferous plants, being fibrous, do not penetrate and di-
vide the soil so perfectly as those of the next family ; and, on
this account, do not leave the soil in so good a condition for
succeeding crops.

Von Thaer has attempted to determine experimentally
the different degrees in which different kinds of grain exhaust

REASONS FOR INTERCHANGE OF CROPS. 273

the soil. If wheat exhaust four degrees, rye will exhaust but
three and a quarter degrees, barley but two and one fourth,
and oats but one six-tenth degrees per bushel of the products.

2. The leguminous plants, such as peas, beans and other
pulse, exhaust the soil much less than the preceding class,
because their leaves are more numerous, and their stalks
more vigorous. They are therefore able to derive more
nourishment from the atmosphere, while their roots divide
the soil more perfectly, and leave it in a better state for suc-
ceeding crops ; hence they have been said to impoverish the
soil.

3. Root crops, such as potatoes, turnips, beets,, carrots,
onions, cabbages and clover, exhaust the soil less than either
of the preceding classes, and are hence called ameliorating
crops. This class are provided with large fleshy and porous
leaves, by means of which they obtain a large portion of their
nourishment from the atmosphere, in the form of ammonia,
carbonic acid and water. As these plants are seldom culti-
vated for their seeds, they rarely mature them the first season ;
hence they derive but little nutriment from the soil. Theii
bulbous or tap roots divide the soil more perfectly, and pre-
pare it for succeeding crops.

The reason why some plants foul the soil more than oth-
ers is also due to their structure. Plants which have small
leaves, permit the weeds to grow, and to appropriate to them-
selves the nutriment which belongs to the crop. They also
exhaust the soil most, while plants with broad leaves cover up
and prevent the weeds from growing, and these also exhaust
the soil the least.

II. The composition of plants explains the reason why
some plants exhaust the soil more than others, and hence
may aid us in forming a judicious system of rotation.

We have seen, p. 169, that different plants require different
quantities and kinds of alkalies and salts, such as potash, soda,
ammonia, magnesia, etc. to complete their growth ; and when
23*

274 IMPROVEMENT OF THE SOIL.

we examine their ashes, we find that some species require phos-
phate of magnesia or phosphates, and others potash, and oth-
ers still, substances rich in nitrogen, such as nitre and ammo-
nia. We have also seen that these substances exist in the soil,
in small quantities, and hence are liable to be removed by a
continued course of cropping.

1. If we take 100 parts of wheat straw they will yield 15.5
parts of ashes. The same quantity of barley straw will yield
8.54 parts, and 100 parts of oat straw only 4.42 parts. The
ashes of all are of the same composition. The principal salts
are phosphates, especially phosphate of magnesia, hence it is
evident " that upon the same field, which will yield only one
harvest of wheat, two crops of barley, and three of oats may
be raised," and this is due to the different quantity of phos-
phates, which they derive from the soil, and if wheat suc-
ceed wheat, these substances will be sooner taken from it.

2. It is evident that if two plants grow beside each other or
in succession on the same soil, they will injure each other if
they withdraw the same alkalies from it; hence wild chamomile
and Scotch broom impede the growth of corn, because they
yield from 7 to 7.43 per cent, of ashes, which contain -{^ of
carbonate of potash, the very alkali which the corn requires.
If these plants succeed each other the same injury will be
done.

3. But on the other hand if two plants grow beside each
other or in succession, which require different quantities of
any alkali for their development, they will flourish well ;
hence if a soil contain potash, wheat and tobacco may suc-
ceed each other although both are exhausting crops, that is,
both require potash ; yet they require different quantities of
phosphates ; thus for example, 10,000 parts of the leaves of to-
bacco-plant contain 16 parts of phosphate of lime, 8.8 parts
silica, and no magnesia ; whilst an equal quantity of wheat
straw contains 47.3 parts, and the same quantity of the grain
of wheat 99.45 parts of phosphates. {De Saussure.) Hence

REASONS FOR INTERCHANGE OF CROPS. 275

the quantity of phosphates extracted from the soil by the same
weights of wheat and tobacco must be as 97.7 to 16, and
when the difference is so great as this, the plants may suc-
ceed each other.

4. Now if we examine what are called the ameliorating
crops, we shall find that they contain a very small quantity of
alkalies or of substances containing nitrogen, or of both. Thus
the leguminous plants contain only traces of salts, p. 266, and
hence they do not injure the crops of corn which are sowed
with or succeed them. The root crops require still less of
these alkalies and salts, and hence their ameliorating effects.

5. If we observe the rotation which is carried on in na-
ture, for example, that pine trees succeed oaks, and oaks
pines, and examine their ashes, we shall find the reason of it.
*' One thousand parts of the dry leaves of the oak yield 55
parts of ashes of which 24 parts consist of alkalies soluble
in water," while the same quantity of pine leaves gives only
59 parts of ashes which contain 4.6 parts of soluble salts,
{De Saussure); and generally those trees whose leaves are
renewed annually, require from 6 to 10 times more alkalies
than the fir-tree or pine.

6. It must be evident, without further examination, that
the causes of the failure of crops when cultivated successive-
ly on the same field, and the reasons for rotation, are to be
found in the kind and quantity of the substances, which each
species of plant extracts from the soil. Some agricultural
writers have held to the hypothesis, that each species of
plant requires different kinds of food, and when it has ex-
hausted its specijic food from the soil, another species will
flourish until its specific food is exhausted. We may learn
from the above examination what this specific food is. It is
the alkali* or salt which the plant requires for its develop-
ment.

It should be remarked, however, that as one alkali may be
* See Liebig, p. 216.

276 IMPROVEMENT OF THE SOIL.

substituted for another in some cases, we must seek still fur-
ther for facts and principles, fully to explain the reasons for
the rotation of crops, and their beneficial effect.

III. The excretions toliich the roots of plants deposit in the
soil have been regarded by some as the most satisfactory mode
of explaining the effect of cultivating the same crop in suc-
cession on the same field, and of the benefits of rotation. Lie-
big considers the view now to be presented, as the only one
deserving " to be mentioned as resting on a firm basis." It
is the theory of M. De Condolle, " who supposes that the
roots of plants imbibe soluble matter of every kind from
the soil, and thus necessarily absorb a number of substances
which are not adapted to the purposes of nutrition, and must
subsequently be expelled by the roots, and returned to the
soil as excrements." Now as excrements cannot be assimi-
lated by the plant which ejected them, the more of these
matters the soil contains, the more unfertile must it be for
plants of the same species. These excrementitious matters
may, however, still be capable of assimilation by another kind
of plants, which would thus remove them from the soil, and
render it again fertile for the first. [Liehig.) In a word,
one species of plants excretes by its roots substances, which
are poisonous or innutritions to plants of the same family, but
which may be assimilated by plants of a different species.

The experiments of iV/«cmVePrmfeps prove, that the roots
of plants do expel matters which cannot be converted into
any of their component parts. Some of these excrements are
of a gummy and resinous character, and are regarded as pois-
onous ; others, are compounds of carbon and are nutritious.
Liebig supposes that these excrements are not, according to
De Condolle, derived from the soil, but from the atmosphere ;
and that it is in this way that a soil receives as much carbon
from the plant as it yields to it. It now becomes an interest-
ing inquiry what state this excrementitious matter is in,

THEORY OF THE INTERCHANGE OF CROPS. 277

whether it is already fitted to nourish other species of plants,
or must first pass through some chemical change 1

It appears that the excrementitious matter of De CondoUe
is matter derived from the soil, and is not fitted to nourish
that species, but may be indispensable to some other plant.
It is undigested matter, and resembles the undigested excre-
ments of animals, which, though unfitted to be assimilated by
one animal, may prove nutritious to another.

The excrements of Macaire Princeps may be derived from
the soil, but they are matters formed in the vegetable organs.
They are compounds produced in consequence of the trans-
formations of the food, and of the new forms which it assumes
by entering into the composition of the vegetable organs.
They are not, therefore, supposed capable of nourishing
other species of vegetables, until a change is wrought upon
them. This change is effected by the agency of the atmos-
phere, water, etc., and they are converted into humus.

These views do not contradict each other ; both may be, and
doubtless are true ; both explain why it is that after wheat,
wheat will not flourish so well on the same soil, and why
one crop must succeed another to keep up the quantity of
produce.

The latter theory, however, explains the fact that the ex-
crements of some plants, affect the same species longer than
others ; for it is evident that the time required for the decay
of the excrements may depend upon their nature, quantity,
and the composition and character of the soil. In a calcare-
ous soil it would be rapidly effected, and hence it is found
that such soils admit of the same crop after the second year ;
or its decay may be effected by alkalies, and this is doubt-
less one of the good effects of adding these substances to the
soil. But when the soil is siliceous or argillaceous, the same
crop cannot be cultivated with advantage until the fourth or
ninth year. Thus for example, " clover will not flourish in
some soils oftener than once in six years, on other soils, once

278

IMPROVEMENT OF THE SOIL.

in twelve years. {Liebig.) The excrements of different
plants require different periods to effect their conversion into
humus ; the excrements of flax, peas and clover, for example,
when grown on argillaceous soils, require the longest period
to effect this change.

From the views now presented, we may see the reason
why the interchange of crops produces effects so highly bene-
ficial. It is because the cultivation of different kinds of
plants on the same field, enables each to extract certain com-
ponents of the soil, which are necessary to it, and to leave
behind or restore those which a second or third species may
require for its growth, and perfect development. In con-
structing a system of rotation, therefore, we must have refer-
ence to the structure of plants, to the alkalies and salts
which each species of plant requires, and to the matters
which they excrete from their roots. We will therefore con-
clude this subject with a series of rules derived both from ex-
perience, and from the views now presented.

1. Two exhausting crops should not succeed each other on
the same field, because their structure is similar, and they de-
rive similar ingredients from the soil.

2. Culmiferous, leguminous and root crops should alternate
with each other, because their structure, composition and ex-
cretions are most diverse, and the least injurious to each
other. If the first crop is a hoed crop, the second should be
a grain crop ; although two hoed crops such as corn and po-
tatoes, or turnips, are better than two grain crops.

3. A grain crop should succeed a hoed crop, rather than
precede it. The reason in this case appears to be, that the
manures can be more perfectly worked into the soil by a hoed
crop, and the soil is left in a better condition for grain.
There are, however, two exceptions to this rule. 1. When
clover makes one crop in the rotation, it is found that wheat
may succeed it with advantage, because they require different
alkalies or salts, and the roots of the clover prepare the soil for

ROTATION SYSTEM. 279

wheat better than most other crops ; hence, it is the practice
of the best farmers to cut their clover early, and turn over the
sod for winter wheat. 2. A grain crop, as oats, may be taken
as a fallow crop previous to wheat or rye.

The following will be found a good system of rotation. 1.
The first year, beans, potatoes or Indian corn with manure. 2.
The second year, wheat, rye, barley or oats, without manure.
3. The third year, roots, such as turnips, carrots or beets,
with deep tillage and compost manure. 4. The fourth year,
the same as the second year, with clover seed. The land
should be smoothed and may remain in clover for a few years,
or a clover crop may be taken, and a rotation, commencing
with wheat and hoed crops, succeed in the same order.

In constructing a rotation system, however, the farmer
should consult the demand for the articles which he raises,
and the character of his soil, as a different system is required
for dry and wet or stiff soils. He may select his crops at pleas-
ure, provided he do not violate the principles already suggest-
ed. The old practice ot growing the same crop for several
years upon the same field, if adhered to, will certainly wear out
his lands, and he will experience, what thousands have be-
fore him, the sure rewards of his folly, barrenness of his lands,
and poverty of purse. It is astonishing that farmers have
continued the practice so long. It would seem that their ob-
servations of what is constantly going forward in nature
would have corrected the evil.

Forests are frequently alternating ; hard wood succeeds
pine ; hemlock, pine and cedar succeed hard wood. Rasp-
berries and strawberries are endowed by nature with roots by
which they change their location. Natural meadows change
their grasses gradually, and the fact is so general, that it may
be regarded as a law of nature ; change of plants being one
of the means which nature employs to keep up fertility, or
to restore her exhausted energies.

A good rotation system forms the basis of good husband-

280 IMPROVEMENT OF THE SOIL.

ry. Without it, the soil may be kept fertile by'the addition of
great quantities of manure and rest, but with it, time and
manure are economized, the soil rendered more and more
fertile, and the products increasingly more valuable.

Rotation of Jields. Rotation of fields is next in impor-
tance to a rotation of crops. By this we mean, that tillage,
pasture and grass land, should alternate with each other.
This practice is in opposition to the very common one, of
devoting a certain portion of the farm perpetually to tillage ;
another to grass, and the remainder to pasture. Wherever
it is practicable, these should alternate, and the same reasons
may be urged as for a rotation of crops. Old pasture lands
often become exceedingly fertile by the droppings of the cattle
and may be cultivated with the best results, while tillage and
grass lands are often benefited by turning them into pasture.
In many parts of New England there are extensive swamps
which may be cultivated, and made the most valuable lands.
These lands are now either wholly waste, or used only as
grass lands.

Sect. 5. Root Culture*

Root culture is not only an important means of improv-
ing the soil in a rotation system, but the products are the
most valuable means of feeding and fattening cattle, and of
producing manure. " It trebles" says Judge Buel, " the
am.ount of cattle-food, and doubles the quantity of manure.
It moreover may be made to supply a large amount of hu-
man food."

The principal roots suited to our climate, are the potato,
turnip, carrot, beet, and those usually cultivated in our gar-
dens. Of these the potato has come into general use. The
beet, carrot and the Swedish turnip are the most profita-
ble, both as to their influence upon the soil, and for the value
of their products. The English turnip is very valuable for
an after-crop, and tends to increase the fertility of the soil,

UTILITY OF ROOT CROPS. 281

especially if cattle and sheep are turned into the field, and
allowed to feed upon them. This means of fertility, and of
producing a large and valuable quantity of fall or after feed,
is almost wholly neglected by our farmers. How easy it
would be, after wheat or winter rye, to sow, say about the
twenty-fifth of July, with turnips, and in October a good sup-
ply of feed would be furnished for the farm stock.

In the cultivation of root crops more attention must be
paid to the character of the soil, and to its condition, than
for the cultivation of grain crops, and hence it is that many
farmers who have tried the beet and ruta baga have failed^
by not attending to the proper conditions ; but if the condi-
tions are adhered to the crop is as certain, and much more
profitable than grain crops. We will now proceed to point
out the requisite conditions for root culture, with the theory
of the action upon the soil. Attention must be paid to the
following particulars.

1. llie soil. This should not be too light and sandy, nor
too stiff and clayey ; a light deep loam or alluvial soil is best
adapted to this crop. If the soil is wet, that is, if water is
suffered to repose upon the sub-soil, the roots will be injured
and the crop fail. The soil should be dry, but not subject
to drought. Depth of soil is a necessary requisite for beets
and ruta bagas in order that the roots may have full liberty
to penetrate as far as needful for their perfection.

2. A rich soil is another requisite to success. This is de-
sirable for all kinds of grain, but especially for root culture ;
for although roots do not draw upon soil, like grain crops,
still there must be abundant food present, in order to give
them that quality and perfection which makes them profita-
ble crops. It may be that there is something in the consti-
tution or vital powers of these plants, which renders a large
quantity of nourishment necessary to their support. They
may not possess the power of collecting food, like other
plants ; they cannot gather up the nutriment so readily, and

24

282 IMPROVEMENT OF THE SOIL

hence must be fed with richer food. The soil must hejinely
pulverized, and, so far as is practicable, freed from stones.
This is necessary in order that the roots may not be ob-
structed ; finally, they should be kept free of weeds. The
ground should be stirred with the cultivator and hoe. If
sowed in rows, as they should be, this may be easily attend-
ed to with the plough and cultivator, without the necessity of
resorting to the hoe more than once in the season.

Theory of the action of roots upon the soil. I. They di-
vide it better than most crops ; 2. they deepen the soil by
their roots; and 3. return to the soil a larger amount of ma-
nure than other crops.

Three acres of grass, at two tons per acre, will give less
than 9,000 lbs. to the cattle-yard, while one acre of ruta ba-
ga or beets, will give 36,000 lbs. or more than four times
as much as the three acres of grass land. It would, there-
fore, be economy for the farmer to raise roots merely for ma-
nure. But the one acre of ruta baga or beets (600 bush-
els) are nearly equal to three acres of hay, as food for farm
stock ; hence the modes by which roots improve the soil, are
dividing and deepening it, furnishing a larger supply of food,
which enables the farmer to keep a larger farm stock, by
which the quantity of manures are increased. Manure is the
great source of fertility. In proportion, therefore, as root
culture is made a part of a rotation system, we should ex-
pect the soils to increase in fertility.

CHAPTER VII.

IMPROVEMENT OF THE SOIL BY MANURES AND TILLAGE.

The improvement of the soil by manures surpasses all
other methods. This subject is one that comes more di-

BY MANURES. 283

rectly under the notice of tlie farmer, than any other pertain-
ing to his employment. It is one which may derive the most aid
from science. In fact it is the most important branch of
Agricultural Chemistry, to point out the best and cheapest
modes of preparing manures in sufficient quantities ; of ap-
plying them to different soils, and for different crops ; and to
explain the theories of their action both in the soil and in
vegetation.

Manures contain all the elements of fertility. They are
composed of decaying vegetable and animal matter (humus
or geine), which constitutes the largest portion of them ; of
a small quantity of silicates, such as silicate of potash ; and
of salts, such as phosphates, nitrates, sulphates, carbonates
and muriates.

Manures have been variously classified. A very ancient
division is into animal, vegetable and mineral ; thus indicat-
ing the source from which they are derived.

The classification proposed by Dr. Dana* appears to be
the most scientific as well as practical. His classes depend
upon the quantity of geinef and salts. This arrangement,
with some modifications, will be adopted in this work.

1. Mixed manures, or those which consist of salts and
geine.

2. Manures which consist mostly of salts, derived from ani-
mal and vegetable bodies.

• 3. Manures which consist mostly of geine.

4. Saline manures, or those which are composed of inor-
ganic salts.

The points most worthy of attention, both in a scien-
tific and practical view, are the nature and composition of the

* Muck Manual, p. 124.

t The term geine is used here not as synonymous with huviic acid,
but with humus ; and wherever it is used, in treating of this subject,
it is intended to include the organic portions of manures, or the de-
caying organic matter.

284 IMPROVEMENT OP THE SOIL

different substances used for manure, their comparative value,
the best methods of preparing, preserving and applying them,
and the theory of their action in the soil. These topics,
therefore, will receive particular attention in the following
sections.

Sect. 1. Mixed Manures, or those wliicli consist of Salts and
Gcine.

This class includes by far the greatest number of sub-
stances which are employed as manures. It includes, 1. the
solid excrements of animals, such as those of the cow, horse,
hog, sheep and fowls, night-soil and poudrette ; 2. animal
substances which contain nitrogen, such as flesh, fish, bones,
hair, wool and soot ; 3. animal and vegetable bodies, which
are destitute of nitrogen, as oils, fats and spent lye of soap-
boilers.

I. Solid excrements of animals. By an examination of
several kinds of excrements, and their known effects, we can
learn the reason of their influence ; and, by comparison, as-
certain what elements give them their cojTiparative value.

1. Cow dung is taken, by Dana, as *' the type of manures,"

or standard of value, with which all others may be compared.

The following is Dana's analysis of 100 parts of fresh fallen

cow dung.

Water 83.60

r Hay 14.60

Organic matter^ -l Bile, and resinous and biliary matter 1.275

[Albumen .175

r Silica .14

Sulphate of potash .05

Geate of potash .07

. Muriate of soda .08

] Phosphate of lime .23

Sulphate of lime .12

Carbonate of lime .12

Loss 0.14

Salts.

100.000

BY MIXED MANURES. 285

Morin's analysis is very similar. Thus 100 parts consist of

Peculiar extractive matter 1.60
Albumen 0.40

Biliary resin 1.80

Water 70.

Vegetable fibre 24.08

Green resin and fat acids 1.52
Undecomposed biliary matt. 60

lOO.Oi)

Others have given analyses varying somewhat from either of
the above. In all cases there is from 70 to 85 per cent, of
water, which of course is of no more value than any other
water. By Dana's analysis a little less than one-sixth
part consists of vegetable matter and salts. By other analy-
ses, a little more than one-fourth is vegetable matter. A large
portion of the vegetable matter is hay, bruised and deprived
of a part of its gum and albumen. But by passing through
the animal organs, the chopped hay has a greater tendency
to decay than common hay. The living power has exerted
a catalytic force, and the elements are disposed to separate ;
hence, nearly the whole soon becomes humus or geine. When
subjected to ultimate analysis, 100 parts of cow dung are
composed of the following organic elements.

Nitrogen .506 i Hydrogen .824

Carbon .204 I Oxygen 4.818

The absolute value of this manure will not depend upon
the quantity of these four substances, which it is capable of
yielding to plants, but upon the quantity of geine, ammoniacal
and other salts. The relative value will depend upon the
proportion of nitrogen, or the quantity of ammonia which it is
capable of forming. All manures may be estimated in a
similar manner. This quantity of ammonia may be deter-
mined with some degree of accuracy from the known quan-
tity of nitrogen ; for 14 parts of nitrogen and 3 of hydrogen
combine to form 17 of ammonia. From these data, 100 lbs.
of cow dung will yield 0.614 or about five-eighths of a pound
of ammonia. This is generally combined with carbonic acid,
and would make about 2 lbs. and 2 oz. of the carbonate of
ammonia, which is known as salts of hartshorn.
24*

286 IMPROVEMENT OF THE SOIL

The salts of potash, soda and lime, are much less. The
whole, including the salts of ammonia, may be estimated at
2Jlbs. in 100 of manure.

The quantity of nitrogen in cow dung has been proved,
by experiment, to exceed that found in the food eaten.
A cow, fed on 24 lbs. of hay and 12 lbs. of potatoes,
yielded daily 85.57 lbs. of dung, or 14 J lbs. of solid ma-
nure. This contained 3.03 of nitrogen, while the hay, etc.
contained only 1.67 parts ; hence, a part must be derived
from the air.

The daily droppings of one cow are sufficient for one half
bushel of corn. The quantity produced per year is sufficient
to fertilize an acre. It will consist of the following sub-
stances.

Carbonate of lime 37 lbs.

Common salt 24 "

Sulphate of potash 15 "

Total 3r025 "

Here is sufficient lime for 60 bushels of wheat, and the straw
grown on 3 acres. But the power of the manure to form
ammonia and nitrates, constitutes its relative value. The
same is true of all other manures.

2. Horse manure. Recent horse dung is highly saturated
with water, and covered with mucus. Its character and nu-
tritive qualities vary somewhat, according to the nature of the
food. Horses fed on grain yield, of course, a more valuable
article, than those fed upon hay alone. According to the
analysis of Dr. C. T. Jackson, 100 grains of recent manure
consists of

Geine

4400 lbs

Carb. ammonia

550 "

Phosphate of lime

71 "

Plaster

37 "

Water 71.40

Veg. and animal mattter 27.00
Silica .64

Phosphate of lime .08

Carbonate of lime .30

Phosph. of magnesia &sod;i .58

100.00

It will be seen that the quantity of vegetable and animal mat-
ter is considerably larger than in cow dung. It is as 14 to
27, or nearly double ; and of course the quantity of nitrogen

BY MIXED MANURES. 287

which it is capable of yielding is nearly double that of cow
dung : 100 lbs. of fresh manure would yield about 3.24 lbs.
of carbonate of ammonia and about .96 of phosphates.

3. Sheep dung is similar to horse dung, but contains a
larger quantity of vegetable matter in a soluble state. It is
also richer in salts ; and the fact that it tends, like the dung
of fowls, to putresence, shows that the quantity of nitrogen
which it is capable of yielding, is greater than either of the
preceding substances.

4. Hog manure. Hog manure is the most valuable of ma-
nures. It contains still larger quantities of soluble matter,
and is capable of yielding a large quantity of nitrogen in the
form of ammonia. We have not seen any analysis of hog
dung, but from its known effects it ranks next in value to

5. Night soil, which has always been celebrated as the
most valuable substance used for manure. The reason for
its powerful effects may be learned from its composition :
100 parts of pure night soil contain

Water 75.3 j Pliosph. of lime and magnesia .4

Animal and veg. matters 23.5

Carb., mur., & sulph. of soda .8 100.0

It will be seen that the quantity of nitrogen, which night soil
is capable of yielding, is about 3J per cent. The quantity of
carbonate of ammonia, which may be formed by the nitrogen,
is about 15 lbs. in 100 of night soil ; hence, if its value is es-
timated by the ammonia which it is capable of forming, it is
more than seven times that of cow dung. Experiments show,
that if land without manure yields 3 for 1 sown, then by the
addition of cow dung, it will yield 7 to 1 ; of horse dung, 10
to 1 ; and night soil, 14 to 1.

The substances, now considered are generally formed to-
gether, and mingled in the cattle yard and hog stye. They
constitute the great sources of fertility to the farm ; and be-
fore describing the other substances, which come under this

288 IMPROVEMENT OF THE SOIL

head, it is important to inquire after the best modes of saving
and preparing them.

This knowledge may be obtained from the nature of the
changes which take place in them, in passing to a state in
which they can be absorbed by the roots of plants.

1. If these substances are exposed to the influence of rains,
nearly the whole of the soluble geinc* the urine and soluble
salts will be dissolved out, and washed away ; hence, they
should always be put under some kind of covering, such as a
shed or barn cellar, which will prevent this waste. The
practice of throwing manure from the stables into the open
yard,t is as wasteful, as it would be for the manufacturer of
soap or potash, to leave his ashes exposed to rains for a long
time before leaching them. This evil may be corrected in
part, by the shape of the

(1) Cattle yard, which should descend from all parts to-
wards the centre; and by covering the bottom of the yard
with swamp muck or peat earth, to absorb the juices which
pass through. As apart of the manure is voided in the yard,
such a shape is needed in order to secure it. About one
third of the manure may be saved by these means. But,

(2) A barn cellar is the preferable mode of preventing
this waste, because it is more convenient, and more perfectly
secures the desired object. This should be of the same shape
as the cattle yard, and lined in the same manner with muck.
If now the hogs are permitted to work over the refuse of the
stables, and the night-soil, a task which they will perform
with admirable skill, provided a little corn is occasionally
added, the leaching process will be entirely prevented, and
the whole will be thoroughly mingled together.

* The term soluble geine,is used to include Iiumic, crenlc and apo-
crenic acids, and their soluble salts.

t Some recommend the practice of frequently sprinkling plaster
over the manure and in stables, to absorb the gaseous ammonia, which
will otherwise be lost.

BY MIXED MANURES. 289

2. If the manure is suffered to remain in the yard or cellar
for any length of time, it should be covered with muck or
earth, in order to absorb the gaseous bodies which will be
evolved.

A series of chemical changes now commence. The whole
grows warm, and after a few months crumbles down to a uni-
form mass, and becomes short muck or rotted manure ; con-
taining a larger quantity of soluble matter (soluble geine and
salts) than it did in the green state. This process was for-
merly called fermentation, but now it includes the processes
oi fermentation, putrefaction and decay. The changes indi-
cated by these terms, all agree in this particular ; that new
compounds are formed, either by a different arrangement of
the elements which compose any one compound in the mass,
or by the agency of air and water, whose elements combine
with the ingredients of the manures. The matter, which has
passed through the animal organs, is much more easily de-
composed than it was before, and a series of chemical trans-
formations commence.

(1) When bodies which contain no nitrogen are decom-
posed, the gaseous products have no odor ; as when sugar is
converted into alcohol and carbonic acid, and in most cases
of fermenting liquors, the process is c?i\]ed fcnnentation.

(2) When bodies containing nitrogen suffer decomposition,
and give rise to gases which emit a disagreeable smell, the
process is called putrrf action. But these changes are of the
same kind, although the latter is most beneficial to the far-
mer, as ammonia is generally formed.

(3) When any body decays at the expense of the oxygen
of the air by a kind of slow combustion, it is called a process
of decay (" eremacausis^^) and differs from fermentation and
putrefaction in the circumstance, that oxygen is absorbed
from the air continually ; while in fermentation, if a small
quantity of oxygen is admitted to the body, sufficient to com-
mence the process, it will continue without further aid from

290 IMPROVEMENT OF THE SOIL

the air, and in putrefaction the air is not needed at all, but
the process is often promoted by excluding oxygen altogether.

The carbon, oxygen, hydrogen, nitrogen and other substan-
ces of which manures are composed, form themselves into
several new compounds which, without attem])ting to point
out all the changes which take place, finally result in the for-
mation of several bodies already considered.

These substances depend upon the conditions under which
the changes take place. If the changes occur in the earth,
they give rise to fossil coal. If they take place near the sur-
face of the ground, or in the open air, which is the case un-
der consideration, they give rise to the substances found in
vegetable mould, p. 215, and in the atmosphere.

Theories of the changes which take place in fermenting
dung-heaps^ in the process of decomposition.

(1) Carbonic acid in large quantities is formed. This re-
sults either from the direct combination of the oxygen of the air
and of water with the carbon of the plant, or from the union
of the oxygen of the air with the hydrogen of the plant to
form water, while the carbon and the oxygen of the vegeta-
ble is evolved in the form of carbonic acid. By this process,
a large portion of the carbon is abstracted in a gaseous form,
and unless alkalies or earths are present to absorb it, passes
off into the atmosphere.

(2) Water is formed at the same time with carbonic acid.
The hydrogen is furnished from the vegetable matter, and the
oxygen from the air. The quantity of water thus annually
formed in the soil, is probably greater than that which falls
in rain on the same surface. In dung-heaps, the quantity of
water formed is far greater than in the soil. In these pro-
ducts there is a genuine process of decay.

(3) As all parts of the heaps are not exposed alike to the
action of the air, the hydrogen and the carbon combine and
form carbureted hydrogen. The hydrogen is fiirnished either
from the vegetable itself, or from the water which is known

BY MIXED MANURES. 291

to be decomposed in the process. This also escapes into
the air.

(4) Sulphur and phosphorus are always constituents of
manures, and combine with the hydrogen and form sulphuret-
ed and phosphoreted hydrogen ; two gaseous bodies of very
offensive odors, which escape in part into the air.

(5) The substances which contain nitrogen yield that ele-
ment to hydrogen, and form ammonia. A part of this sub-
stance is absorbed by water and the vegetable matter, and a
part is thrown off into the atmosphere ; the remainder, which
constitutes probably the largest portion, combines with car-
bonic acid, forming carbonate of ammonia, and with other
acids, as the muriatic and nitric, which are formed during
the process.

The above, with the exception of water, are the gaseous
bodies given off in the process, and as the most valuable part
of the manure is liable to be dissipated in this way, v/e have
the best reason for covering the fermenting heap with a thick
coating of earth or peaty matter.

(6) Nitric acid is usually formed in this process. Some
have supposed that it results from the transformation of am-
monia ; others suppose that it may obtain its nitrogen direct-
ly from the plant, or from the atmosphere. The acid being
formed, combines with the potash and forms nitre or salt-
petre ; and with other bases which may be present, such as
soda, lime and ammonia.

(7) Sulphuric and hydrochloric acids are also formed ; the
latter acid deriving its chlorine from the salt which exists in
animal excrements. It is probable that other acids are formed.
All of them, however, are combined with bases in the form
of salts. It is rare that any acid, excepting the carbonic, ex-
ists in a free state.

(8) The solid matters which remain, are found to consist
in part of humic acid, humin, extract of humus, crenic and
apocrenic acids. The acids are combined in some cases

292 IMPROVEMENT OF THE SOIL

with bases, and the whole taken together has been called geine
and humus. But' when the fermenting heap is exposed to the
rains, the salts and the vegetable matters are dissolved by the
water, and pass down into the soil or run to waste ; hence,
the reason for the direction above given, to place under the
heap a thick bed of earth or swamp-muck, to absorb these
liquid matters.

When these changes have proceeded awhile, the whole mass
is converted into an effectual manure, into geine and salts, fit-
ted for any soil or crop. If the heap contain a large quan-
tity of animal matter , the tendency to putrefaction is much
increased, a much larger quantity of ammonia is formed, and
also a larger quantity o( nitrates.

3. If the manures are carried, in their green state, direct-
ly upon the field, as a top dressing, the air of course, and
not the crop, receives the larger portion of their valuable
products. But if they are spread, and turned into the soil,
the changes which we have described take place much more
slowly, a circumstance which, on many accounts, is highly
favorable to vegetation. The plant requires a constant and
regular supply of nutriment, and this process supplies it.
The heat, which always attends their decompositions, acts
with great power, and with the best effect, especially in cold
wet soils. The gaseous matters are directly absorbed by
the loam, and more perfectly retained than they can be in
the heap. Still it may be doubted, whether the manure, from
its diffusion through the soil, is as favorably situated for those
chemical changes, which must take place, before it can nour-
ish plants. It may well be doubted whether so large a quan-
tity of soluble geine and salts will be furnished in this way,
as when placed under fitting circumstances in heaps, and
whether more vegetable matter will not be dissipated in the
air.

If, however, soils are wet and cold, manures should be ap-
plied in the green state, rather than permitted to ferment in

BY MIXED MANURES.

293

the yard. It may be remarked, generally, that in all cases
where manures are applied without forming them into com-
post heaps, they should be applied in the green state, but when
composted with vegetable matter, it is far preferable to allow
them to pass through the fermenting processes.

6. Poudrette is night soil mixed with ground peat and
plaster, and dried so as to be rendered inodorous and porta-
ble. If the sulphate of lime and peat are added before it is
dried, the ammonia will be converted into a sulphate, or ab-
sorbed by the peat and retained. The value of good pou-
drette depends upon the quantity of ammonia and geine. It
has been valued in comparison with cow dung as 14 to I.*

7. Chiano is a very valuable manure. It is the excrements
of birds, and is found in the greatest abundance on the islands
of the Southern Ocean, where it forms beds from eighty to
ninety feet in thickness. It is composed, according to Voel-
ckel, of

Urate of ammonia .9

Oxalate of ammonia 10.6

Oxalate of lime 7.0

Phosphate of ammonia 6.0

Phos, of ammonia and mag. 2.6

Sulphate of potash 5.5

Sulphate of soda 3.8-

Muriate of ammonia 4.2

Phosphate of lime 14.3

Clay and sand 4.7

Undetermined organ, sub. 32.3
of which 12 per cent, is soluble.

This substance is said to render fertile the soils of Peru,
which do not contain a particle of organic matter. It will
be seen from its composition that it contains all the elements
of fertility, a large quantity of salts, and 12 per cent, of sol-

* There is yet another form of poudrette, which though much used
in France, has not been introduced here. It is almost one-half ani-
mal matter, and it is formed without any offensive evolution of gas,
by boiling the offal of the slaughter-house, by steam, into a thick
soup, and then mixing the whole into a stiff paste, with sifted coal
ashes, and drying. If putrefaction should have begun, the addition
of ashes, sweetens the whole, and the prepared " animalized coal," as
it is termed, or poudrette, is as sweet to the nose, as garden mould.
It is transported in barrels from Paris to the interior, and is a capital
manure. — Dana's Muck Manual.

25

294 IMPROVEMENT OF THE SOIL

uhle organic matter. Liebig appeals to this example to prove
that plants will grow without humus !

8. Pigeon dung and that from domestic fowls is similar
to guano. The former has been proved by experiment to
be f stronger than horse dung. The manure of fowls has
been applied with the best effects to peach trees, vines and
other plants, which after a few years present the most luxuri-
ant and healthy appearance. It may be applied by mixing
one part of manure with 8 or 10 of water, and put around
the roots.

II. Animal bodies, such as flesh, skin, gristle, sinews
and bones, form by decomposition most powerful manures.
They produce much larger quantities of ammonia than fer-
menting dung heaps, and are much richer in salts, contain-
ing in fact all the substances which are necessary to sup-
port the vegetable organs. The following table shows the
composition of animal bodies.

{Sulphate and phosphate of lime,
Phosphates of soda, magnesia and ammonia,
Sulphate and muriate of potash and soda.
Carbonates of potash, soda, lime and magnesia.

V ♦ Ki C Benzoate, ^

vegeiaDie i Acetate, \ Of potash, soda, lime.
^^^^^- ^Oxalate, ^

Animal C Urate of ammonia.
Salts. \ Lactate of ammonia. •

Oxides of iron, manganese and silica.

Animals and vegetables contain several substances, which
appear to be identical. Gluten, vegetable fibrin, albumen
and legumin, are vegetable principles, and the correspond-
ing substances in animals are fibrin, albumen and casein.
The last two are identical in composition with vegetable al-
bumen and legumin. These principles are combined with
alkalies, earths, sulphur and phosphoric acid. When de-
prived of their inorganic portions, they have been referred to
a single organic principle, called protein, which is thus con-
stituted.

BY MIXED MANURES. 295

Oxygen 21.2.88 I Carbon 55.742

Hydrogen 6.827 | Nitrogen 16.143

IM.
or in symbols C'^^H^SN^O^'*. It appears now to be well estab-
lished that this substance is the basis of animal bodies.
Fibrin or flesh, and albumen or the white of eggs, are com-
posed of protein and sulphur. "

Horny matter is of two kinds, soft and compact. The
soft variety includes the cutiele of the skin, and the lining
membrane of the internal passages and sacs.

The eompact variety includes horns, hoofs, nails, claws,
scales, feathers, hair and wool. These substances all con-
tain sulphur, lime, magnesia, and from ^ to 2 per cent, of
bone earth.*

1. Horns and hoofs. The shavings and piths of horns
and hoofs of neat-cattle make a very powerful manure. About
0.3 per cent, is phosphate of lime and earthy matter ; the re-
maining substances are, in 100 parts.

Carbon 51.540 i Nitrogen 17.284

Hydrogen 6.7D9 \ Oxygen and sulphur 24.397

The horns and piths may be cut with an axe or ground in a
bone-mill, then mixed with green manure, a bushel to a load,
spread upon the field, and buried with the plough. The fer-
mentation of the dung promotes the decay of the animal mat-
ter, and large quantities of ammonia will be evolved.

2. Nails and claivs are composed of

Carbon 51.019 I Nitrogen 16.901

Hydrogen 6. 824 | Oxygen and sulphur 24.608

These of course will yield a large quantity of ammonia, and
therefore they will constitute a powerful manure.

3. Hair is composed of

Carbon 50.652 | Nitrogen 17.936

Hydrogen 6.769 I Oxygen and sulphur 24.643

. (Scherer.)

* Dana.

Carbon

50.653

Hydrogen

7.02!)

Nitrogen

17.710

296 IMPROVEMENT OF THE SOIL

4. Wool contains, in 100 parts,

Oxygen and sulphur 24.608

100.000

5. Feathers are composed, in 100 parts, of

Carbon 52.427 I Nitrogen 17.893

Hydrogen 7.213 | Oxygen 22.467

Wool, woollen rags, and the refuse from woollen manufactories,
hair and feathers, contain an oil in addition to their protein,
which increases their value, and renders them excellent ma-
nures. The washings from the wool annually consumed in
France, would yield sufficient manure for 370,000 acres of
land. This wool-sweat is an excellent manure.

G. Glue, jelly, etc. is derived from cartilage, skin, bone
and tendon, by boiling them in water ; but it is not found in
healthy animals. It constitutes a powerful manure.

7. Bones are composed of animal matter, phosphate of

lime and of magnesia, and carbonate of lime: 100 parts of

the bones of the ox, as analyzed by Davy, yielded, of

Decomposable anini. matter .51 j Carbonate of lime 10.

Phosphate of lime 37. ' Phosphate of magnesia 1.3

The value of bones depends upon their power of producing
ammonia and salts. For the former purpose, they are at
least 8 or 10 times as valuable as cow dung, and the quantity
of salts is 66 times that contained in an equal quantity of that
substance. They constitute, then, a most concentrated ani-
mal manure, and have been long used by the most intelligent
farmers for improving their soils. For this purpose they are
crushed in a mill, made for the purpose, and constitute
Bone dust. The value of this manure may be estimated
by the quantity which is imported into England, amounting
animally to 800,000 dollars worth. It is estimated that this
adds to the agricultural products more than 16 million
bushels of grain.. Bone dust is now used in this country to a
considerable extent. One bushel to a load of yard manure,
increases its value, as determined by experiment, one half.

BY MIXED MANURES.

297

Vegetable matter 30.70

Extract, matter & nitrog. 20.00
Carb. of lime and traces

of magnesia 14.66

Acetate of lime 5.65

Sulphate of lime 5.00

Phosph. of lime & of iron 1.50

Bone dust not only acts with great power, but its effects
continue a long time ; and, as it contains salts of lime, it is
particularly useful to the soils of New England.

8. Sootj in its composition, is allied to animal solids, and
may be described in thi^ connection. It is a very valuable
manure, as appears from its composition : 100 parts of soot
contain, of

Acetate of potash 4.10

Muriate of potash .36

Acetate of ammonia .20

Acetate of magnesia .53

Silex .95

Carbon 3.85

Water 12.50
300.00

If the value be determined by the quantity of salts and of nitro-
gen, in equal weights of soot and cow dung, the salts are as
20 in the former to 1 in the latter, and the ammonia as 40 to 1.
The application of soot-water (6 quarts of soot to a hogshead of
water) to green-house plants, has been attended with the best
effects.

So valuable a substance ought to be saved with the utmost
care, and either applied directly to the soil or to compost
heaps. The latter use of soot is the most profitable, because
it is capable of decomposing a large quantity of vegetable
matter, as peat or swamp muck.

III. Animal and vegetable substances destitute of nitrogen.
The only substances belonging to this class are oils and fats.
In order to understand the action of these bodies as manures,
it will be necessary to ascertain their constitution. Fatty bodies
are acids combined with a peculiar base called ^Zycerme, which
is similar to stearine and margarine or fats, and to oleine or oils.
The acids are stearic, margaric and oleic acids.

When oils and fats are exposed to the air, they yield great

quantities of carbonic acid, and become converted into the

above acids. The carbonic acid acts upon the silicates, and

the organic acids act upon the alkalies in the soil, and form

25*

298 IMPROVEMENT OF THE SOIL

soaps, which, as salts, produce a most powerful effect in the
processes of vegetation.

1. Soap-boilers^ spent lye. In the process of soap-making,
the alkali combines with the acid of stearine, margarine and
oleine, forming stearates, margarates and oleates or soaps,
while the glycerine remains in solution with the salts.

This latter substance is somewhat similar to geine, and is

thus constituted.

Carbon 40.07 I Hydrogen 8.92

Oxygen 51.00

The oxygen, hydrogen and carbon exist in such proportions
as to form water, carbon and carbureted hydrogen. It may
yield to plants the same elements as humic acid. As about
8 per cent, of oils and fats is glycerine, it will readily be per-
ceived, that the large quantity of this substance in spent lye,
must render it a very valuable manure.

But this is not the only substance which gives to it its
value. There are also various salts ; the kind depending
upon the alkali used to form the soap.

1. If potash is used (as it always is to form soft soaps),

every 100 lbs. of soft soap requires about 8 bushels of ashes,

and the spent lye contains, of

Sulphate of potash 6.5 lbs. I Silicate of potash 1.8 lbs.

Muriate of potash 0.3 " |

and a small quantity of potash in a free state. This adds
greatly to the value of this article as a manure.

2. If now common salt is added to make the soap grain, or
to convert the soft to hard soap, the salt is decomposed, the
soda takes the place of the potash, and forms soda soap, while
thechlorine combines with the potassium, forming the chlo-
ride of potassium (muriate of potash), which is added to the
spent lye. The quantity will depend upon the quantity of
salt* used.

* In a boil of 2,000 lbs. of soap, about 7 bushels of salt are usually
added.

BY ORGANIC SALTS. 299

3. If the alkali is barilla or white ash, then the spent lye
will contain, in addition to its glycerine, salts of soda; but as
less common salt is added, in this case/ the quantity of sul-
phate and muriate of soda will be less than the corresponding
salts of potash. Ordinarily the spent lye of hard soap contains,
per gallon, of

Sulphate of soda 6| oz. i Glycerine Alb

Muriate of soda . ^Ib. |

"While that from hard soap contains, per gallon, of

Glycerine ^ lb. I Sulphate of potash U lbs.

Muriate of potash (chloride Silicate of potash 2A oz

of potassium) ^5 "

It becomes an important question, whether so valuable a ma-
nure can be imitated by artificial methods. As soluble geine
is similar to glycerine, the elements of spent lye from soda
soap may be formed from swamp muck, ashes and common
salt. Take 100 lbs. of peat, 1 bushel of salt, 2 bushels of
ashes and 200 gallons of water. Mix the peat and ashes ;
moisten with water and add it to the salt in solution ; stir it
occasionally for a week, and it will be fit for use.*

Sect. 2. Manure, consisting of Salts derived from Animal
Bodies.

This class of manures includes the liquid evacuations of
animals, which are salts dissolved in water. These salts are
different from those which will be described under the head
of mineral or saline manures, because they are formed of an
animal acid; that is,of an acid which is produced in the ani-
mal organs. This acid is found in urine, and is called uric
acid. It is composed of

Carbon 36.11 i Oxygen 28 19

Hydrogen 2.34 | Nitrogen 33;36

The quantity of nitrogen renders it a powerful manure, as
it becomes the food of plants. This acid appears to be'de-

* Dana.

300 IMPROVEMENT OF THE SOIL

rived from an animal principle called urea; which may be
obtained from urine in transparent, colorless crystals, very
soluble in water, in which it suffers no change; but when
mixed as in urine, it is converted into carbonate of ammonia.
Alkalies produce the same effect.
Urea is composed of

Carbon 19.99 I Hydrogen 6.66

Oxygen 26.66 | Nitrogen 46.66

The oxygen, carbon, hydrogen and nitrogen are in such pro-
portions, that they are converted ivholly into carbonic acid
and ammonia ; hence, the quantity of urea in urine, is equal
to its weight of carbonate of ammonia. The urea and uric
acid, render the liquid excretions of animals equally valuable
with the solid evacuations ; and much more valuable, when
vegetable matters are employed to absorb the gaseous products.
1. Urine of the cow. The liquid evacuations of the cow
are composed of

Water 65

Urea 5

Phosphate of lime 5

Sal amm. and mur. of potash 15
Sulphate of potash 6

Carbonate of potash and amm. 4

~Ioo

It will be seen, that the quantity of ammonia in the urea,
as compared with cow-dung, is as 5 to 2 ; and in the other
ammoniacal salts as 15 to 2, or about 4 times the quantity of
the salts of ammonia in the liquid, that there is in the solid
evacuations.

:*»'100dbs. of this urine yield 35 lbs. of the most power-
ful salts ; hence, the importance of saving the urine by in-
troducing into the yard or barn cellar substances, as peat,
which will prevent it from being washed away. If it is true,
as has been shown by experiment, that a cord of loam satu-
rated with urine is equal to a cord of the best rotted manure,
and if one cow would furnish sufficient annually to manure an
acre and one half of land, while the solid evacuations will not
fertilize more than one acre, it must be evident to every far-

BY ORGANIC SALTS. 301

mer, that at least one half of his manure is wasted, if exposed
to the influence of rains, and the ordinary action of the at-
mosphere.

2. Urine uf the horse. The urine of the horse, and some-
times of other herbiferous animals, contains hippuric acid,
which takes the place of the uric acid. The result, however,
in vegetation is nearly the same, as the acid in both cases
gives rise to ammonia by decomposition. The value of
horse-urine will appear from its composition. 100 parts
contain

Water G4.0

Urea .7

Carbonate of soda .9

Carbonate of lime 1.1

Hippurate of soda 2.4

Muriate of potash .9

iocToo

From its composition, it is at least equal in value to cow-dung.
3. Human urine is equally valuable with either of the pre-
ceding. It is composed, in 1000 parts, of

Sal ammoniac .459

Sulphate of potash 2.112

Muriate of potash 3.674

Common salt 5.06'J

Phosphate of soda 4.267

Phosphate of lime .209

Acetate of soda 2.770

Urate of ammonia .298

Urea with coloring matter 23.640
Water S67.511

The quantity of salts in 1090 lbs. of this urine is upwards
of 42 lbs. The salts of ammonia makes it about equal in
value to cow-dung, pound for pound ; but as the other salts
are more than double, 1000 lbs. of human urine is worth
nearly 2000 lbs. of the best cow-dung.

If now we compare the quantity of salts in the solid, with
these in the liquid evacuations, we shall find that human,
horse and cow dung, contain upon an average, 1 per cent.,
while human urine contains 4.24 per cent., that from the
horse 6, and that from the cow 35 per cent.

There is no substance, however, which varies more in com-
position than urine. Its composition depends upon the kind
of food,* but it is always a most valuable manure. No farmer

* " White turnips give a weaker liquor than Swedish. Green

302 IMPROVEMENT OF THE SOIL

should permit it to run to waste, but should so prepare his
cattle-yard by loam or swamp-muck, and by plaster, as to
save these invaluable products of his stables, and of his own
dwelling.

As the urine is generally mixed with the solid excrements
in the barn-cellar or cattle-yard, it increases the value of this
manure, it promotes its decay, and adds its own salts ; but
if the whole is exposed to the influence of atmospheric agents,
it facilitates their action, and aids in depreciating its value;
hence, it is generally wholly lost to the farm. Farmers ought
generally to know this, and to be apprized of the fact, that
one half at least of their manure is wasted. The prepara-
tion of liquid manures will be further noticed under com-
posts.

Sect. 3. Manures composed mostly of Geine.

The refuse of the stables and of the farmer's dwelling, are
the general sources of manure. But there are certain artifi-
cial preparations, which are equally efficacious, and which
most farmers may employ to increase the fertility of their
soils.

These sources are decaying vegetable matters, formed in
various ways, into composts. The vegetable substances em-
ployed for these purposes, originate from two classes of plants,
sea-weeds and land plants; and the manures which they
form, differ in several important particulars, but agree in
yielding all the elements of fertility.

In order to exhibit the facts and principles, connected with
this species of manures in a practical light, it will be neces-
sary to examine the composition of the substances employed

grass is still worse. Distiller's grains are said to be better than either
of these. Doubtless, the liquids of fattening kine is richer in ammo-
nia during this period, for it contains a partof the nitrogen not carried
away in the milk." — Dana.

i

BY MANURES FROM SEA-WEED. 303

for this purpose, and the changes which are wrought upon
them, in their conversion into vegetable food.

I. Sea-iceed. Sea weeds form a kind of manure which is
much used along the sea board. The manure is formed from
several species of plants, which are washed upon the shore by
the waves and either carted directly upon the soil or used for
litter and composted with other substances. The following
are the principal varieties.

1. Ribbon loced, or narrow-leaved kelp, when green, is
nearly four-fifths water. When dry, 400 grains, burned to
ashes, yielded, of

Carbonate of soda (not weighed)
Phosphate of lime "^ 3.3

Carbonate of hme 2.U

Si lex 0.2

Magnesia 3,5

*' The vegetable matter of kelp is very gelatinous, and melts
down during fermentation into a semi-liquid mass." The
Scotch farmers make great use of this substance, and prefer
laying it directly on to the soil, in its green state.

2. GwMkg.t££3i moss contains a gelatinous matter, similar to
animal gelatine. It is used for food, and makes a delicate
blanc-mange. < > ^ ^. ^

3. Rock ?veed is highly* gelatinous in its nature and very
valuable as a manure.

4. Eel grass consists mostly of water and is much less
valuable.

5. Sea coral is often thrown up with sea weeds, and adds
greatly to their value. It is composed of the following sub-
stances : 100 parts contain, of

Animal matter 14 I Phosphate of lime 1

Carbonate of lime d,5 | — rrrx

The quantity of salts contained in sea weeds renders them a
very valuable manure.

Preparation and application of sea iveeds. If sea weed is
to be transported to some distance, it should be dried, to evapo-
rate the water. It may then be spread directly upon the

304 IMPROVEMENT OF THE SOIL

soil and ploughed in, or formed into compost with fish, or the
refuse of the cattle yard. In either case it is an active ma-
nure ; but its effects are not lasting, probably owing to the
ease with which it is decomposed and either dissipated or ab-
sorbed by the roots of plants. It may be used for litter, to
absorb the liquid and gaseous products of the stables, with
the best results. Its value has been fully tested by many
farmers who reside in the vicinity of the sea.

II. Peat, sivamp muck and pond mud. These sub-
stances are very abundant in the eastern part of Massachu-
setts. Almost every farm throughout the country contains
either peat, muck or mud in sufficient quantity for farming
purposes.

1. Peat is derived from the decayed roots of sphagnous
mosses, ferns, stalks of swamp-plants and decaying leaves ;
the peat moss constitutes the principal mass. There is also
a small quantity of mineral matter, such as silex, clay, lime
and magnesia, either mixed with it or combined with vege-
table acids. Some varieties contain sulphate of lime (gyp-
sum), oxide of iron and of manganese. The value of peat as
a manure may be seen from its composition. The mean of
20 analyses of the peats of Rhode Island, by Dr. Jackson,
gave the following results.

Water from 10 to 25 pr ct.

Iron and alumina 1.34 percent

Ashes, when burned, 24.07 "

Lime 1.32 «

Vegetable matter 72.39 "

Magnesia .32 "

Silfca 4.31 "

Four specimens contained a small quantity of potash, and
one specimen contained 1.2 per cent, of phosphate of magnesia.
It will be seen that peat contains a large quantity of vegetable
matter and of salts.

2. Sivamp muck consists of the pairings of the peat, and is
less compact. It is found in every meadow, and includes the
hassocks. It also includes the variety of peat which has be-
come partially decomposed, and the mud of salt marshes.

3. Pond mud is found at the bottom of ponds, when dry,

BY PEAT MUCK AND POND MUD. 305

and in low grounds. It consists of from 15 to 20 per cent,
of vegetable matter, which has been washed down from the
high lands and mixed with earthy materials. Dr. Dana has
given the composition of 10 specimens of Massachusetts peat
and swamp muck, dried at a temperature of 300° F. The
average quantity of ingredients is 85 per cent, of vegetable
matter ; of which 29.46 is soluble and 55.03 is insoluble ;
15.9 per cent, are salts and silicates. The composition of
pond mud is very different, only 5 to 8 of insoluble and from
6 to 9 per cent, of soluble vegetable matter or geine. The salts
of lime, however, are abundant, being about 2 per cent. It
should be remarked that the proportion of the soluble to the
insoluble portion is much greater in the mud than in the peat^
and hence the effects of this substance will be more immedi-
ate, but not so lasting as peat and muck.

When peat is first dry, it contains from 78 to 98 per cent,
of water. In drying, it shrinks tv/o-thirds or three-fourths of
its bulk. When green, it contains, of

Water 85. I Silicates .5

Salts of lime .5 | Humus 14.0

looo

If, now, we estimate the value of fresh dry peat as compared
with cow dung, we shall find that the two substances are con-
stituted almost exactly alike. The salts and the geine or hu-
mus, in every cord of peat, are equal to those produced by the
cow in three months. But there is one important difference.
The cow dung is capable of producing a large quantity of
ammonia, but the peat only contains slight traces of it. Still
there is found crenic and apocrenic acids, which may serve
the purpose of the ammonia, by yielding their nitrogen in the
processes of vegetation.

The action of the ammonia, as we have remarked, is to in-
duce decay and consequent conversion of the insoluble geine
or humin into humic, crenic and apocrenic acids, or into solu-
ble geine. If, now, there is any process of adding to the
26

3Q(5 IMPROVEMENT OF THE SOIL.

peat muck, either ammonia or any substance which will pro-
duce the same effect, we may convert it into cow dung,
cord for cord. This may be done in the compost heap m the

following ways. , c u v^

1 Compost of peat tvith alkalies. The action of alkalies

upon vegetable matter, to induce decay, has been frequently

referred to. The action of all are alike in this respect ; but

the products are not all the same, and it becomes a question

of areat practical importance what alkali to use, and what

quantity to employ, in order to produce the best effect with

the least expense.

The alkalies employed to decompose the peat, and convert
it into cow dung, are soda, ammonia and potash.

Ammonia is generally too expensive an article for h.s
purpose. In other respects it would be the best, as all that
would be needed would be to add about 2 lbs. of the carbonate
or sulphate to every 100 lbs. of peat. As there are other al-
kalies in the peat, 1 lb. in practice has been found to answer
the purpose. Potash and soda are almost the only alkalies
which can be obtained in sufficient quantities, and at a pnce
sufficiently moderate to answer the wants of agriculture.

In order to determine the relative quantit.es of the above-
named substances, it will be necessary to resort to their equiv-
alents ; 1 part of ammonia is equal to 2 of soda, and 2 parts of
soda to 3 of potash; or their equivalents are nearly as the
numbers 1,2,3. But these alkalies are found m the state ot
salts; that is, combined generally with carbonic acid, car-
bonate of ammonia and soda or wkitc ash These are about
equal in their effects, while pot and pearl ash, which are car-
bonates of potassa, produce but about two-thirds the effect^
Hence, as cow dung contains 2 per cent, of ammonia, if we add
to fresh dry peat 2 per cent, of carbonate of ammonia, 2 of soda
ash, or 3 per cent, of potash, they will, in each case, convert
it imo that substance. By this estimate, as eac^i cord, when
dry weighs 3216 lbs., it would require 84 lbs. of ammonia or

BY COMPOST MANURES. 307

soda ash, or 276 lbs. of potash. But when the peat is dry, it
loses nearly three-fourths of its bulk ; and hence would re-
quire about 736 lbs. of soda ash, or 1104 lbs. of potash.
These proportions are found, by experiment, to effect the de-
composition of the peat. But it is also found that a much
less quantity of alkali will convert peat into cow dung. This
is probably due to the fact, that not more than one-third of
the ammonia contained in cow dung is active, and hence
about 1 per cent, of potash will be sufficient for the compost
heap. This will require for every cord oi fresh peat 92 lbs.
of potash, or 61 lbs. of soda ash, or 16 bushels of common
ashes.

If these are composted together, a cord of the compost
ought to produce effects precisely similar to cow dung. And
experiments, so far as they have been made, seem to confirm
the theoretical proportions. But a smaller quantity of alkali
will render pe:it a very valuable manure ; 20 lbs. of white ash,
or 30 of potash to a cord, are found in practice to be as
profitable as larger quantities. If spent ashes are used, 1 part
of ashes to 3 of peat may be used.

Care should be taken to have the compost heap protected
by a shed or a thatch of straw, and worked over two or three
times before carrying it upon the land. In the process of
fermentation which takes place, nitrates are formed and other
salts of a highly salutary character.

There are other alkalies, which may be composted with
peat, such as the spent lye of soap-manufacturers and lime.
If spent ashes are used, a greater or less quantity of lime is
also added. Some regard the lime which the ashes contain as
less likely to render them beneficial in their effects. But if lime
and common salt are both added to the peat, the lime will
produce effects highly beneficial.

Take one bushel of salt dissolved in water, mix it with a
cask of slacked lime, so as to make them into a thick paste,
and let them remain for a week. This may then be mixed

308

IMPROVEMENT OF THE SOIL

with three cords of peat, and shovelled over for about six
weeks, and than applied to the soil.

Theory. The theory of the changes which are produced,
may be known from the elements which are brought together.
The salt is converted into soda and hydrochloric acid. When
the lime is brought into play, the acid combines with it and
forms a soluble salt ; the soda acts upon the peat, evolves its
ammonia as above, and becomes carbonated. Mutual decom-
position of the carbonate of soda and muriate of lime now
takes place, and carbonate of lime in minute portions is
formed throughout the mass, ready to act upon the silicates
and liberate their alkalies, and upon the geine, while the soda
and muriatic acid are so combined as to form salt again.
Composts of this description may be formed at an expense of
not more than $2,25 per cord, and are believed to be very
effectual manures.

A compost may be formed which will prove effectual, if
the above does not. Add 61 lbs. of lime, and 61 lbs. of sal-
ammoniac to three cords of peat, and an article will be form-
ed, at an expense of less than $5,00 per cord, which will be
fully equal in value to common yard manure.

2. Composts of peat with animal inatter. Peat and swamp
muck may be decomposed in a compost heap with refuse ani-
mal matter. '* The carcass of a dead horse," says Lord Mea-
dowbank, *' which is suffered to pollute the air with its effluvia,
has been happily employed in decomposing 20 tons of peat
earth, and transforming it into the most valuable manure."

Urine, will also decompose it by the action of its ammonia,
and other salts ; hence, the importance of having peat and
swamp muck at hand, on to which the liquid excretions may
be poured. In some countries, as in Flanders and in China,
large tanks are provided into which the urine is conducted,
and then either applied in the liquid state, or mixed with
loam and peat earth. " Liquid manures," says Mr. Young,
*' are of the same value as the solid •, one ton of solid dung

BY COMPOST MANURES. 309

will make four tons of compost, and four tons more may be
made by the urine discharged by the cattle in the same time."

Night soil is similar in its effects. Fish also make an ex-
cellent compost, if lime is added to neutralize the acids or
combine with the oils. Any refuse animal matter, such as
woollen or cotton waste, and the washings of wool from wool-
len factories, may be mixed with peat and a most powerful
manure formed.

3. Compost of peat with green manures. We have al-
ready described the process of preparing yard and stable ma-
nure ; underlaying it, and covering it with loam or peat earth.
The direct object in this case is to protect the manure, and
save the valuable products of fermentation, putrefaction, etc.
But in the process now to be described, the object is to de-
compose the peat, by means of the ammonia which green
manures evolve. The quantity of ammonia in 100 lbs. of
cow dung as we have seen, is about 2 lbs. This is sufficient
to convert 200 lbs. of peat into a substance of equal value
with cow dung. The urine which is mixed with stable ma-
nure will more than double this quantity; hence, if 3 cords
of peat are mixed with one of stable manure, there will be
formed 4 cords of manure equal in value to cow dung. These
proportions agree with experience, and may serve to confirm
us in the process, which has been recommended by practical
farmers.

Process. In order to prepare a compost-heap with green
manures, the peat should be dug and exposed to the rains for
a while, to be deprived of its tannin and acids ; then, when
partly dry, it may be carried into the cattle-yard or shed, or
on to the field, and mixed with green manure. A layer of
peat should form the base of the heap, then a layer of manure,
and then alternate layers of peat and manure, ending with a
thick layer of peat. The shape should be conical, and cov-
ered, if exposed to rains, with a thatch o{ straw, or with boards.
If lime or ashes are added, they will facilitate the process of
26*

310 IMPROVEMENT OF THE SOIL

decomposition. The heap, in the course of six weeks or two
months, may be shovelled over and more peat added, if it
is still in a state of^ fermentation. Some recommend the ap-
plication of lime at the time of shovelling it over, in order to
liberate the ammonia. It should then be carried directly
upon the field.

The changes which take place are similar to those in fer-
menting dung-heaps. The result is the same, soluble and in-
soluble geine and salts. Lord Meadowbank, who first called
attention to this subject, states " that in every diversity of
soil, it has given returns, in nowise inferior to the best barn-
yard dung, applied in the same quantity, and that it is equal,
if not preferable, in its effects for the first three years, and
decidedly superior afterward."

The testimony of several New England farmers who have
tried this compost, is that *' three parts of peat with one of sta-
ble manure, make a compost which is equal in value to its
bulk of clear stable-dung, and is more permanent in its ef-
fects."

It may be applied to any soil, either in the hill, or spread
broad-cast and turned in ; or it may be used as a top-dressing
upon grass lands. In the absence of peat and swamp muck,
composts may be formed with loam, straw, leaves, or any
vegetable matter, which will absorb the gaseous and liquid
products.

The quantity of peat and swamp muck in the eastern part
of Massachusetts, is sufficient to render all her barren hills as
fertile as the prairies of the West. The only difficulty there
is in the case, is to persuade farmers to prepare it, and apply
it to their soils.

Methods of applying manures. It has been a question of
frequent discussion, whether manures should be applied to
land in the green, or rotted state. The best answer to this
question is, that they should not be applied in either state ; but
should always be made into composts, and applied after fer-

BY COMPOST MANURES. 311

mentation ; and the reason is, that every cord of clear stable-
dung may help form four of good rotted manure. But as
farmers will continue to apply their manures in a pure state,
a few rules may aid them to do it in the best manner.

1. For cold, stiff or wet soils, sheep and horse manure are
the best, and should be applied in the green state, spread up-
on the land, and immediately turned under.

Theory. The reason is, that such soils require the heat
incident upon fermentation of the manure. And, as it is dif-
fused through the soil, the roots of plants feel its full in-
fluence. Such manures also render the soil lighter and
dryer.

2. For light, sandy or gravelly soils, hog or cattle dung
may also be applied in the green state, spread and ploughed in
as above. Horse manure should be fermented, before being
applied to such soils.

Theory. These soils do not require the heat, and a less
quantity is produced in fermentation by cattle than by horse
manure. By applying it in the green state, the gaseous pro-
ducts are saved, and one third of the manure ; as it has been
found by experiment, that one third at least, is wasted in pass-
ing to the state of short muck in cattle yards.

3. Green manures, however, should never be applied to
any but a hoed crop. If wheat or rye are sown on lands ma-
nured at all, it should be rotted manure.

Tlieory. In a hoed crop, fermentation is most active
in mid-summer, when the stalks and leaves need its influ-
ence ; but in a grain crop, the kernel is ripening at that
period, and fermentation is injurious to the process. If the
straw is increased by the large quantity of carbonic acid
which fermentation produces, the harvest will be hazarded ;
for the supply of food to the grain cannot be assimilated, and
disease and consequent blight will ensue.

4. Rotted manure acts with greater power in the early
part of the season than green ; and hence, farmers generally

312 IMPROVEMENT OF THE SOIL

prefer it. But the green manure shows its superior effects in
the harvest. The best rule is to apply to hoed crops a small
quantity of rotted manure in the hill, to give the young plant
a vigorous " start," but to spread the greater portion in a
green state, to act upon the crop in mid-summer. The gen-
eral practice of manuring in the hill is, by the best farmers,
almost wholly discontinued.

Sect. 5. Saline Manures, or those consisting of inorganic
Salts.

Mineral substances act as manures, when they enter in-
to the composition of plants. They act as amendments
or correctors, when they improve the texture or neutral-
ize acids. They act as solvents or converters, when they
induce changes in animal and vegetable bodies, or con-
vert them into vegetable food. They act as stimulants, when
they excite the living powers of plants by producing electri-
cal changes, and other effects not well understood.

The substances, classed as mineral manures, are salts ; that
is, they consist of acids combined with alkalies, alkaline
earths and metallic oxides. As fertility depends upon salts
and geine, and, as the base of the salt, or alkaline portion,
acts wholly upon geine, and in one uniform manner, p. 220,
salts may be classed, with reference to the peculiariti/ of their
influence, by their acids.

In this respect, salts may be divided into two classes.
1. Those salts whose acid nourishes plants ; such are nitrates,
carbonates and phosphates. 2. Those salts, whose acid
poisons plants, or yields but a small quantity or no nutri-
ment ; such as sulphates, hydrochlorates or muriates.

I. Salts ivhose acid contains the elements ivhich nourish
plants. This class includes three families, which may be de-
scribed as nitrates, phosphates and carbonates.

I. Nitrates. In this family of salts, nitric acid is com-
bined with several bases. The three principal salts which

BY SALINE MANURES. 313

are used in agriculture are those of ammonia, potash and so-
da. Nitrate of ammonia is formed in fermenting dung
heaps, but is rarely applied artificially.

Nitrate of potash, or nitre, is composed of 54 parts, by
weight, of nitric acid (aquafortis) and 47 of potassa. This
substance has long been a celebrated saline manure. Its
effects are not only powerfiil but permanent. Upon what
does its utility depend ? In order to answer this inquiry,
we have only to refer to principles already suggested.

Every 100 lbs. of nitre contain about 46 of potash. This
acts only upon the vegetable matters of the soil, and is proba-
bly let loose from its combination, by growing plants (by ca-
talysis). We have already noticed the influence of potash
upon peat. 200 lbs. of nitre would furnish potash sufficient to
decompose one cord of peat or muck. The action of the acid
is more complicated. It contains 40 parts of oxygen and 14
of nitrogen. It may therefore be decomposed, and yield nitro-
gen and oxygen to the vegetable products, p. 16#/ But its
oxygen probably acts both upon the vegetable matter and the
silicates. By its action on the humus, a part is rendered
soluble, and carbonic acid is formed, which acts upon the
silicates, and liberates their alkalies. If the above is a true
representation of the changes which take place, it proves that
nitre is a most valuable substance to be applied to the soil.
Experiment has shown that 100 or 150 lbs. of nitre, per acre,
will produce the most gratifying results. It may be spread,
or mixed with the manures.

Nitrate of soda is nitric acid combined with soda, in the
proportion of 54 parts of the former to 31 of the latter. Its
action is precisely similar to nitre. The soda acts upon veg-
etable matter, and the acid indirectly upon the silicates. The
quantity applied may be about 100 or 150 lbs. to the acre,
spread broad-cast, or mixed with the manures.

The above substances, including nitrate of ammonia, are
the food of vegetables, and hence are properly classed as ma-

314 IMPROVEMENT OF THE SOIL

nures. There is, moreover, no danger of adding them in too
large quantities. They are nourishers, and their action, as
salts, does not produce insoluble compounds, but tends to
render inert bodies active and useful. The nitrates are all
exceedingly mild, although very active, and useful in their in-
fluence upon vegetation.

2. Phosphates. This family includes substances already
considered, such as bone, earth, horn, hair, hoofs, etc. The
only mineral phosphates, which may be used as manures, are
phosphate of lime (apatite) and phosphate of magnesia ; but
these substances are not found in sufficient quantities to ren-
der their application practicable. Phosphates act very much
like nitrates, the acid is food, and exists in vegetables Jn
combination with magnesia. It also acts upon silicates, and
eliminates their alkali.

Bone dust is principally phosphate of lime, and is a highly
concentrated manure.

3. CMonates, This family includes common limestone,
marl and air-slacked lime ; potash, ashes and white-ash or
barilla. Carbonate of lime is known under the names of
chalk, shells, marble, marl, limestone, etc. The most com-
mon forms in which it is used in agriculture, are shells,
marl and air-slacked lime; although ground limestone has
sometimes been applied to fertilize the soil. Salts of lime
have long been used for agricultural purposes. Their bene-
ficial effects were known to the ancients. They have been
used in England, France and Germany for the last 100 years,
with the very best results, and yet practical farmers are not
all agreed whether lime is useful or hurtful in its effects.
Experience shows that it is sometimes injurious and at others
highly beneficial. Any theory, therefore, which shall enable
us to decide the quantity which may be safely used (for it ap-
pears that the bad or good effects depend mostly upon the
quantity employed), must be of the highest benefit to the
practical farmer.

BY SALINE MANURES. 315

Theory. Carbonate of lime acts like all saline compounds ;
the base is let loose, by the action of the living plant, and
acts in its caustic state upon insoluble vegetable matter, and
converts it into vegetable food. The carbonic acid acts upon
the silicates and obtains the potash and soda, which react up-
on the humus, and render larger portions of it soluble. The
action is slow, but the effects are sure.

When lime is applied in a caustic state, it slowly absorbs
carbonic acid, and becomes a carbonate. If a large quanti-
tity is used it may form a super-salt with humic acid, and
become inert because insoluble. It is in this way that it
proves injurious. But this state cannot always last, for the
salt will, in time, be decomposed and rendered useful.

When acids exist in the soil, both the caustic and carbon-
ate of lime tend to neutralize their effects ; hence it aj^ears
that the base of lime acts in a four-fold capacity, as a con-
verter, a ncutralizer, a decomposer, and a retainer. , >

(1) Lime acts as a converter, when it convertajlpsgetable
fibre into vegetable food. This appears to be the most im-
portant use of lime, and the most difficult to explain. It has
been referred to its " catalytic" power or to the action of
presence, but whatever may be the nature of the force, it is
well established, that when lime is brought into contact with
vegetable matter, it hastens its decay. The humic or geic
acid thus formed combines with it, and becomes a soluble
salt, ready to enter the vegetable organs.

(2) Lime acts as a neutralizer, whenever acids exist in
the soil in a free state. Some soils are called acid soils, and,
as the carbonic acid is displaced by most other acids, the
lime will combine with the acid and neutralize its effects.
Peat and smamp muck often contain acids, which may be
neutralized in this way ; hence lime should be applied to peat
earth, before it is used.

(3) Lime acts as a decomposer, when it decomposes any
inert or injurious substance in the soil, as metallic salts. Veg-

316 IMPROVEMENT OF THE SOIL

etable matter forms, with alumina, a substance which is per-
fectly inert and useless (humate or geate of alumina). Lime
will decompose it, and form a soluble salt (humate or geate
of lime).

Sulphate of iron, or copperas, exists also in many soils, and
is highly poisonous in its influence ; lime will decompose this
salt, and form sulphate of lime, or plaster, an effective ma-
nure.

As lime soon becomes carbonated in the soil, if applied in
a caustic state, its action is nearly the same as when applied
as marl or ground carbonate. In both cases, the acid acts
upon the silicates, and decomposes them, hence lime will de-
compose the silicate of potash in spent ashes, and render the
the alkali active.

(4) Lime acts as a retainer when it forms super-salts with
humic, crenic and apocrenic acids. It thus locks up the
vegetable matters, which it has converted into food, and this
is one rOTison of its injurious effects. Still the matter is re-
tained and will in the end all be appropriated. This effect
must take place whether the quantity is large or small ; but
if there is a small quantity of vegetable matter in the soil, a
large quantity of lime should not be applied. We have here
a solution of the mystery relative to the effects of lime.

If lime is added in large quantities, and in a caustic state,
it induces decay of the humus, and the formation of carbon-
ic acid. It combines with both of the products, and if the
proportion of vegetable matter is small, it will form so large
a quantity of it into super-salts, as to injure the crop ; hence
it may be concluded, 1. That lime is useless on soils destitute
of vegetable matter, and that it will not render them capable of
sustaining vegetation. 2. That lime is often injurious on soils
containing but a small quantity of vegetable matter. 3. That
lime is highly useful, when applied to soils containing a large
proportion of humus. If therefore, lime is applied to soils,

BY SALINE MANURES. 317

vegetable matter must also be added, to ensure its good ef-
fects.

The utility cf lime in agriculture, when properly applied,
is well established by experience. The quantity required is
small, one per cent., and even twelve bushels to the acre, are
valuable additions. " A quantity of lime," says Mr. Puvis,
" which does not exceed the thousandth part of the tilled
surface layer of the soil, a like proportion of drawn ashes, or
a two-hundreth part, or even less of marl, are sufficient to
modify the nature, change the products, and increase by one
half, the crops of a soil destitute of the calcareous principle."
Sir John Herschel found that minute portions of calcareous
matter, " in some instances less than the millionth part of the
whole compound, are sufficient to communicate sensible me-
chanical motions, and definite properties to the bodies with
which they are mixed." As such effects seem to be electrical
in their character, we may conclude that there is a fifth office
of lime, to act as a 5#/;?m/«?«#, by developing electrical cur-
rents. Upon the whole, we should prefer potash to lime, but
the latter is unquestionably beneficial in its action, and may
be applied in small quantities, as a cask to an acre, without
any fear of injury, and with the certainty of ultimate benefit.

Carbonate potash. Potash is a carbonate, that is, it con-
sists of carbonic acid combined with potassa. The action of
the potash has already been considered, p. 306. It is some-
times applied to the soil from 100 to 150 lbs. to the acre.
But the form in which it is usually applied is that of

Ashes. The value of ashes depends upon the kind of wood
from which they are derived. Those fi-om hard wood are
more valuable than those from soft.

One hundred parts of hard wood, such as dry oak, beach,
birch, etc. yield 2.87 parts of ashes. One hundred parts of
dry pine yields only 00.83 of ashes, while 100 parts of wheat
straw affords 0.44 per cent. The ashes consists of two parts,
soluble and insoluble portions.
27

318 IMPROVEMENT OF THE SOIL

One hundred parts of the soluble, from hard wood, are
composed of

Carbonic acid 22.70 I Potash and soda 67.G6

Sulphuric acid 64^

Muriatic acid 1.82 \ 99.86

Silex .!!5 I

It will be perceived that the salts are not all carbonates,
although the greater proportion of them are. One hundred
parts of the insoluble portions contain

Carbonic acid

35.80

Oxide of manganese

2.15

Phosphoric acid

3.40

Magnesia

3.55

Silex

4.25

Lime

35.80

Oxide of iron

.52

Peat ashes contain carbonate, phosphate and sulphate of
lime.

Ashes, then, are composed of salts and silicates ; they con-
tain potash, lime and soda, and their use depends upon the
action of these alkalies, which render them an efficient ma-
nure. Ashes are excellent for grass lands. One bushel of
ashes contains 5J lbs. of potash, a quantity sufficient to de-
compose 200 lbs. of peat earth.

Leached ashes correspond to the insoluble portions, and
part of the lime is added, one peck of lime to a bushel of
ashes, to render the lye caustic by absorbing the carbonic
acid. Spent ashes, however, generally contain about 50 lbs.
of silicate of potash per cord, so that they act both by their
alkali and by their lime. Silicate of potash depends for its
action wholly upon being converted into the carbonate of
potash, and hence may be classed with the carbonates.

When ashes are composted with peat, they form a cheap
and valuable manure; but should not be applied to the soil
in large quantities, unless vegetable matters are also added.
Ashes applied to light, dry soils, always act beneficially. On
wet soils, they sometimes introduce mosses.

Barilla or white ash, may be classed as a carbonate ; its
has already been considered, p. 367. The latter may

BY SALINE MANURES.

319

be applied to the soil, 100 lbs. to the acre, with the most per-
fect confidence in its utility. The former contains carbon-
ate of lime, about half of its weight, with carbonate of soda.
The ashes from antharcite coal contain carbonate of lime, al-
umina and oxide of iron, and are useful saline manures.
Ashes of all kinds are particularly useful on grass lands.
Peat ashes contain so much gypsum that they generally act
with greater power than those from wood.

II. Salts whose add does not enter into the composition of
plants, and which is poisonous. This division includes, 1.
Sulphates, such as sulphate of lime, iron, potash and soda.
2. Muriates or chlorides, as common salt, chloride of calcium,
and of potassum.

1. Sulphate of lime, or plaster, has long been used as a sa-
line manure. It has been proved by experiment, that " a
bushel of plaster per acre, or even the one four-hundreth part
of one per cent, produces effects on alluvial land, which shows
its good results, as far as the eye can reach." This effect
can be explained : on the supposition that plants decom-
pose the salt, and let loose the lime upon the geine ; the acid
must act upon the silicates, and form sulphates of potash, of
soda, and (if silicate of lime exist) of lime. In this way the
plaster reproduces itself.

Plaster has been found in some plants. It is supposed by
Liebig, to act chiefly by condensing ammonia, and retaining
it for the wants of vegetation.

Sulphate of iron, or copperas, is not applied to any but a
calcareous soil, and the result is the formation of gypsum,
by the action of lime to decompose the copperas.

2. Chlorides. Common salt is beneficial upon some soils ;
it acts by the soda which it contains. Thirty bushels to the
acre, has produced good effects. It may be best employed
for composts.

Spent lye from soap-works has already been considered.
In all cases, the action of salts depends upon the presence

320

IMPROVEMENT OF THE SOIL

of life. A living plant introduced into the soil, causes all the
chemical forces to strive together to supply the necessary con-
ditions for the perfection of the vegetable productions.

Application of saline jnanurcs. The quantity of salts
used on any soil, must be determined chiefly by experiment.
The following are the conclusions of M. Lecoq, who publish-
ed the result of his experiments in his Prize Essay, 1832.

** 1. Salts, so far as possible, should be used in powder.

2. If used in solution, they must be diluted with a large
quantity of water.

3. Saline manures may be advantageously used on all soils.

4. They answer best on light and dry soils.

5. They produce good effects on wet meadows, but must
be used in large quantities.

6. It is preferable to spread salts at two epochs, in order to
increase their action.

7. Some soils, especially those where mineral springs ex-
ist, and those around volcanoes, are already charged with a
sufliciency of saline matter.

8. In too large quantities, saline matters injure vegetation.
In too small quantities, they have no action.

9. The proportions that give the best results, are from 150
to 330 lbs. to the acre.

10. One hundred and fifty pounds to the acre is the best
proportion for grazing lands and meadows.

11. These proportions must be varied with the nature of
the soil ; and 150 to 250 lbs. per acre, is generally the best
quantity for light soil, but may be increased to 300 lbs. on
mowing lands, and even to GOO lbs. on wet meadows, where
we may use double this amount without injury to vegetation.

12. These are the proportions for sea salt and muriate of
lime ; they should vary with the other salts.

13. Fishery salt is prefered, as it is cheaper.

14. Sulphate of soda may be used in quantities from 300
to 600 lbs. per acre.

BY SALINE MANURES. 321

15. Acetate of lime exercises but little action on plants in
quantities below 300 lbs. to the acre, and above this amount
is injurious.

16. Ammoniacal salts exert a very marked action on vege-
tation, and may be employed in the quantities of 150 lbs. of
the sulphate, or 100 lbs. of the carbonate, per acre.

17. Sea salt, in certain cases, may replace gypsum in
artificial meadows ; 150 lbs. of salt being equal to 5000 of
gypsum.

18. Nitrate of potash increases considerably the crop, when
used in quantities of 150 to 200 lbs. per acre.

19. The best time for spreading the salts is when the
young plants begin to put forth their leaves. At the epoch
of germination they are more injurious than useful.

20. Salts do not favor the production of seed, unless asso-
ciated with organic manures.

21. They retard the maturity of plants, and give more de-
velopment to the foliage, thus opposing evaporation of the
liquids which they contain.

22. Burning the soil may be regarded as belonging to the
class of saline manures, since salts are formed with the or-
ganic matters that the soil contains, and exert a very marked
influence on vegetation."

This last means of obtaining salts may be practised upon
peat meadows, where there is a large quantity of peat. The
surface may be pared with a plough made for the purpose,
and the turf collected in heaps and burned. Then by spread-
ing the ashes, the peat will be rapidly converted into vegeta-
ble food. This practice, however, should not be resorted to,
unless there are acids in the peat, or a large quantity of land
containing peat. The vegetable matter is more profitably
employed for composts. Salts may be obtained generally at
a cheaper rate, than to burn manure in order to obtain them.

In conclusion, we would impress it upon the mind of the
New England farmer, that the preparation and proper appli-
27*

322 IMPROVEMENT OF THE SOIL

cation o^ manures, are the sources upon which he must main-
ly rely for success in his profession. If all other subjects are
disregarded which are here discussed, let him not neglect
this ; for if this subject is properly attended to, the rest will
follow in its train.

Sect. 6. Improvement of the Soil hy Tillage.

By the term tillage, we mean those operations, which ap-
ply directly to the cultivation of farm crops. It includes the
processes of ploughing, harrowing, rolling, hoeing and weed-
ing. These processes belong to all kinds of tillage, whether
intended to improve the soil, or to exhaust it.

We have already considered these operations in their re-
lation to vegetation. In this section these processes are con-
sidered with reference to their influence upon the soil. But
as the treatment is the same, whichever object is immediate-
ly to be pursued, only a few remarks need be added to those
which have been made in the first chapter.

The great object of tillage is to render the soil light, to
promote the circulation of air and water, a free extension of
the roots of plants, to facilitate the chemical changes in
the soil, and an equal distribution of the manures. The ope-
rations of ploughing, harrowing, hoeing, etc. have already
been referred to, and our limits forbid any further remarks
in this connection. These implements need no description.*

Fig. 18. The utility of the

roller (Fig. 14.)
depends upon the
fact that intersti-
ces or pores are
left after plough-

* Ploughs are now manufactured by Nourse, Ruggles & Mason,
Boston, which perform tliis part of tillage in a very superior manner.

BY TILLAGE. 323

ing, or the frosts of winter, which expose the roots of plants
to injury. The roller breaks down the lumps, and gives
compactness to the whole mass. The good effects of passing
the roller over fields of winter grain or grass lands in the
spring, have been fully tested by experience. The earth,
which the frost has rendered porous, and which does not
therefore embrace the roots, is rendered more com pact. On
light sandy soils, the use of the roller is almost indispensable, by
closing the pores and preventing the evaporation of the mois-
ture, which such soils most require, although they are more
liable than any other to yield it up.

Fig. 19.
The utility of the
cultivator (A. Fig.
19), may also be
referred to, as this
implement may be
employed to save
the labor of hoeing.
It also leaves the ground in a better state than the plough,
when used among hoed crops. But it is not our purpose to
describe the instruments of tillage.

We may observe, in conclusion, that thorough ploughing,
harrowing, hoeing, weeding, etc. will incorporate the ma-
nures with the earthy ingredients, and promote, in the best
manner, the influence of all those atmospherical and other
agents which are required to Jit the soil to sustain a vigorous
and healthy vegetation. It is hardly necessary to add, that
the ease of cultivation and the quantity and quality of produc-
tions, will depend, materially, upon the faithful and season-
able performance of this branch of the art of husbandry.

324 PRACTICAL AGRICULTURE.

CHAPTER VIII.

PRACTICAL AGRICULTURE.

Under the head of practical agriculture we wish to in-
clude the modes of cultivating the farm crops; the charac-
ter and value of each species of grass, grain and root, which
are usually cultivated by our farmers. As these modes of
culture are derived from experience, an opportunity will be
afforded of testing the truth of many principles discussed in
the preceding chapters. This subject, however, must be
treated in a concise and general manner. We shall present
the views of practical farmers, and attempt to show their con-
sistency with scientific principles. Another topic under this
head will be the relation of farm stock to the cultivated crops,
a few suggestions upon which will close the chapter.

Sect. 1. Cultivation of Grains.

The following are the most important cultivated grains :
Indian corn, oats, barley, rye and wheat.

I. Indian corn, or zea mais, is a native of this country, and
was unknown toEuropeans until after the discoveryof America.
In consequence of the different climates and soils in which it has
been cultivated for a long series of years, there have been pro-
duced several varieties, differing more in appearance and hab-
its than many distinct species of plants. We know how
some of these varieties are produced, and this may instruct
us in the selection of the seed, in order to improve any par-
ticular variety, or to obtain a new one. One mode of obtain-
ing varieties of corn, is by selecting the seed. Thus, for
example, a celebrated variety has been produced in the South-
ern and Western States, by selecting the first year the seed
from stalks which bore two ears, and taking the top ear to
plant. The second season there were some stalks of three

CULTIVATION OF CORN. ' 325

ears ; and the top ears from these were then taken and
planted ; and this process was continued for a series of years.
The consequence was, that the stalk became very high ; and
the number of ears upon a stalk increased from one to five,
and even eight. It should be remarked, that though this
process gave a distinct variety, yet it would have been a
much more valuable variety, in this case, if the lower ears
had been taken ; by which means the stalks would have been
lower, the ears nearer the ground, and hence much less liable
to injury, and more likely to be early, plump and well filled.
By the selection of seed, also, an early or late variety
may be obtained. Thus, for example, if those ears which
ripen first, are selected from year to year for seed, in the
course of eight or ten years an early variety may be obtained ;
and if those ears which ripen last are taken, under similar
circumstances, a late variety may, in like manner, be ob-
tained. Hence, in the selection of seed, the farmer should
consider what variety he wishes to obtain. In the Eastern
States, an early crop is desirable. In the Southern States a
late crop. The number of rows on an ear depends upon
similar treatment. Some prefer eight-rowed, others twelve
or more. All these varieties may be produced by selection
of seed and proper culture.

The seed corn should be selected in the autumn, before
harvesting, and hung up by the husks. Before planting, it
is a good practice to soak it for twenty-four hours in cop-
peras-water or brine, as this will facilitate germination and
prevent the wire-worm from eating it up.

Soil. The soil for Indian corn should be a light sandy or
gravelly loam. A rich dry soil is always to be prefered. In
heavy moist soils, it will not flourish as well as potatoes and
most other hoed crops. It should be planted after grain
crops or clover. Corn may be manured in the hill with
compost or rotted manure. It is much better, however, to
spread green manure or compost, and turn it into the soil.

326 PRACTICAL AGRICULTURE.

The corn may then be planted in rows, about three feet apart,
and from five to six kernels in a hill, lightly covered with
loam. It is desirable in theory to spread fifteen or twenty
loads of green manure to the acre, and turn it under, to act
upon the crop late in the season, and then to put five or six
loads of compost in the hill, to give it an early start ; this
corresponds with the experience of the best farmers.

The after culture consists in two or three hoeings, or one
cleaning with the cultivator and two hoeings. The first hoe-
ing should remove the earth from the roots; the second
should raise it into the form of broad, flat hills. Some ex-
periments, however, seem to prove that corn is best cultivated
on a flat surface, with a tillage depth of from six to twelve
inches ; and theory would lead us to the same conclusion.
The practice of making hills, injures the roots and exposes
them to the influence of drought.

The modes of harvesting corn are various. Judge Buel,
after repeated experiments, recommends the practice of cut-
ting it up by the roots, and shocking it in the field, when the
kernel has become glazed, so as to yield but little juice when
broken open, and while the leaves are still green. We must
confess that this practice has, upon the whole, more reasons
in favor of it than any other.

It saves labor ; for the expense of cutting and securing an
acre is not more than that of topping it.

It adds to the ciuantity of grain ; because, when the tops
are removed, the nourishment which would go to the kernel
is cut off; while, by letting the whole stand for a ^&w days,
and then cutting it up by the roots, the process of assimilation
will continue to go on for three or four days afterward.

It increases the quantity of fodder and preserves its nutri-
tious properties ; for it is not exposed so directly to the influ-
ence of the weather, and a larger quantity of the green parts
is preserved. And, finally, it yields more manure and is se-

CULTIVATION OF WHEAT. 327

cured against early frosts ; for if it is cut when it is full in

the milk, it will ripen in the shock.

The expense of this crop, and the value of its proceeds,

may be estimated as follows.
Ploughing, 4,00 I Produce, 35 bushels, $35,00

Manure, 12,00 Corn fodder, lo 00

$45,00

28,75

Profit, $16,25

Furrowing, ,75

Planting, 1,50

First hoeing, 2,50

2d and 3d hoeing, 4,00

Gathering, 2,00

Husking, 2,00

,75

This, we think, is a very low estimate of the value of this
crop ; for the manure ought not, all of it, to be charged to the
corn, as it generally suffices for two more crops. And al-
though the average may not be more than 35 bushels to the
acre, still 40, 50, 60 or even 120 bushels are often obtained
m the Northern and Middle States, and in some cases 170
bushels in the South and West.

Broom-corn is cultivated to a considerable extent in the
valley of the Connecticut river, and is a very profitable crop.
The particular mode of its cultivation is not a matter of gene-
ral interest. It is a crop which yields a great amount of
matter ; but as it rarely matures its seeds, it does not ordina-
rily exhaust the soil as much as Indian corn.

2. Wheat has been cultivated from the most remote an-
tiquity. With us, two species are known, winter wheat {triti-
cum hybermim) and summer wheat [triticum astivum).

The grain itself appears under two varieties, the flint or
dark colored, and the white or thin-skinned. Some varieties
are bearded, and others are bald. The white soft-skinned
varieties succeed best in dry soils and warm climates; the
red and flint varieties prefer a moist soil, and a cool tempera-
ature.

In selecting seed wheat, any variety may be improved ;
and It has been found that the best method is to go into the

328 PRACTICAL AGRICULTURE.

field when it is fully ripe, and select the longest and fullest
heads, from which seed loheat may he raised the folloicing year.
If this course is pursued, the crops will constantly increase in
value.

The quantity of seed \)et acre for winter wheat, may be one
bushel and a half, if sowed in September so that the stalks
may spread themselves. If sown in the spring, at least two
bushels per acre should be employed.

The soil for wheat should be a deep loam, perfectly fine,
dry and light; containing a good proportion of clay and car-
bonate of lime. It should be thoroughly and deeply pul-
verized.

Wheat should not be sown on green manure, but a clover
ley, or a potato crop the previous year is the best prepara-
tion.

The depth at which it is sown should be two inches, un-
less the land is very finely pulverized; in which case it will
flourish much better, if it is placed only one inch below the
surface. The ground must be thoroughly drained, and if
the sub-soil plough is used, it will very much increase the
value of the crop. Wheat requires phosphates and substan-
ces rich in nitrogen. It will therefore be improved, by add-
ing to the soil, salts of ammonia, lime, clay, saltpetre or
bone manure.

There is nothing worthy of notice in the mode of harvesting
this crop. It should be left standing until the grain is fully
ripe and hard.

Diseases and enc?nies. Wheat is subject to disease, and to the
attacks of insects, which are frequent causes of its failure,
and which render it in many places an uncertain crop. The
principal diseases are rust, smut, and mildew or blight.

1. Rust is a well known disorder, in which the straw be-
comes covered over with a red powder like iron rust. This
stops the growth, and renders the grain shrivelled. Rust
takes place either in a season of drought, or in July and Au-

DISEASES AND ENEMIES OF WHEAT. 329

gust, when the weather is damp and warm. The wheat is
thus forced to such a rapid growth that the vessels are burst,
and the sap exudes and causes the rust. In either case there
is no known remedy.

2. Mildew or blight gives to the plant a purple or bluish
cast, resembling the mould on damp walls ; and is supposed
to be due to a species of parasitic plant, a fungus which
attaches itself to the stalk. This happens during warm, wet
weather, or heavy dews. The only remedy is to brush off the
water in the morning by dredging the field with a rope.

3. Smut is of two kinds. The first kind is seen in the heads,
about the time of the ripening of the grain ; the heads soon dis-
appear, leaving nothing but the naked stalks. The second kind
appears in the form of a black dust, which soon spreads itself
over the field. The grain is not destroyed, but the flour is
rendered black and poor. This is also supposed to be a spe-
cies of fungus, as it can be propagated through a field. This
disease may be prevented by soaking the seed in strong brine
or stale urine, sprinkling it while wet with slacked lime, and
leaving it for twenty-four hours before sowing.

The enemies of wheat are the wire-worm, Hessian fly and
grain insect.

1. Wire-worm. This worm is well known to farmers, and
its ravages are mostly confined to the sward. This effect
may be remedied by ploughing in the fall, so that the frosts
of winter may destroy the worm.

2. The Hessian fly is found as a maggot between the leaf
and the culm, in the first joint of the plant, and, by bedding
itself in the stalk, destroys it. No certain remedy, for the
ravages of this insect, has as yet been found. Late sowing
will sometimes carry the crop beyond the fly-season.

4. The grain insect appears in the form of a fly, hovering;
over the field about the time the grain is in blossom. It de^
posits its eggs, from which a yellow maggot is hatched, and
appears in the head after it has destroyed the grain. A

28

330 PRACTICAL AGRICULTURE.

complete preventive against this insect has been discovered,
which consists simply in sprinkling, at the flowering season,
slacked lime over the grain while wet. Mr. Colman thinks
that this may generally be relied on as a certain preventive.

The barberry bush has been thought to be injurious to
wheat, rye and barley, by causing it to blast.

Rye is the seed of secale cereale, and has also been long
cultivated for food. In the north of Europe, it ranks next
to wheat for bread, and is used, for the same purpose, in
many parts of this country, particularly with Indian corn
for brown bread, a very healthy and cheap article of diet.
Rye is not regarded as a very profitable crop, but if we con-
sider the fact, that it will grow on sandy plains, Avith little
^(>r no manure, and yield from 10 to 20 bushels to the acre,
we must regard it as of great value; for it is the only grain
which will grow on soils containing more than 85 per cent,
of sand.

The time of sowing rye is in August or September, either
after potatoes or corn, or upon a summer fallow. The quan-
tity should be about one bushel to the acre. It may also be
sown in the spring, but the winter rye is generally the most
certain and productive crop. The general practice of our
farmers is, to plough up sandy plains once in three years, and
take a crop of this grain, and then let the soil rest for a year
or two, and take another crop. This practice cannot be too
severely censured. If clover were sown with the rye, on
such lands, and turned in with the stubble, the soil would
soon become enriched and fitted to bear any crop. If the
clover will not grow, spread on ashes, plaster or lime, and as
soon as the roots become fixed in the soil, there is not the
least diflficulty in rendering the land as fertile as you please.
Instead of 8 or 10 bushels to the acre, once in three years,
our farmers ought to raise, at least 25 bushels with root crops
and corn in the interval.

CULTIVATION OF OATS.

331

The expense of cultivating rye, and the average product,
may be stated per annum as follows.

Ploughing,
One bushel seed,
Sowing and harrowing,
Reaping,
Threshing,

2,00
1,25
1,00
2,00
2,00

$8,25
Rye is subject to a disease called ergot

Produce on an average,
15 bushels, at $ 1,25
Straw,

Deduct expenses,

Net firain, <l!

lft,75
5,00

23;75

8,25

$T5;50

It is a kind of
black spur in the head. It has been supposed to be a spe-
cies of fungus.

Oats {avena sativa) are cultivated as an article of food,
both for man and beast. They will grow on any soil, and
are generally cultivated after corn or potatoes without ma-
nure, although some prefer to sow on green sward. Three
bushels are required to the acre. The land should be plough-
ed once and thoroughly harrowed. Oats are a very sure
crop, and may be estimated at 40 bushels to the acre upon
an average. In consequence of their demand at livery sta-
bles, they usually bring a price above their intrinsic value.

The expenses of cultivation, and the returns, are generally
as follows.

Seed, 3 bush, at 50 cts..
Cradling and harvesting,
Threshing,

2,00
1,50
2,00
3,00

$8,50

Produce on an average,

40 bush, at 50 cts.,
Straw,

$
Deduct expenses,

Net gain.

20,00
10,00

'3o;oo

8,50
21,50

It will be seen, that this is a very profitable crop, especial-
ly as oats bring ready money, in almost any market. But
if proper pains are taken, and the land properly prepared,
crops of 60 bushels may be obtained. Governor Da-
vis of Worcester, Mass. has raised 100 bushels to the acre.
It should be remarked here, that there are two principal va-
rieties ; the common oat, with a spreading top, and the Tar-
tarian, or horse-mane oat, so called, because the seed hangs
in clusters on one side. As the two varieties ripen at differ-

332 PRACTICAL AGRICULTURE.

ent times, they should not be sowed together. The produce
is equal in both varieties, but the Tartarian has a shorter
stratv.

Barley (hordeum vulgare) is extensively cultivated, partly
as an article of food, and partly for malt liquors and ardent
spirits. The summer barley is the only variety cultivated in
the United States.

Barley seed, before sowing, should be steeped twenty-four
hours in soft water, in order to promote the germination of
all the grain and its ripening at the same time.

The soil should be rich and mellow, although it will flour-
ish tolerably on a clay soil, free from weeds. Crops of tur-
nips or potatoes are the best preparation for this crop. The
seed should always be sowed upon a fresh-stirred soil, as
early as the land will allow in the spring, and from 2 to 3
bushels should be allowed to the acre. The barley may be
i^radled in the same manner as oats. The value of this crop
may be thus estimated per acre.

Produce, 30 bush, at 80 cts.

Ploughing, 2,00

Seed, 3 bush, at 80 cts. 2,40

Sowing and harrowing, 1 ,50

Harvesting, 2,50

Threshing, 2,80

$11,20

per bushel, 24,00

Straw, 5,00

2;',00

Deduct expense, 11,20

$ 17,80

This is probably about an average for this crop, yet fifty-
four, and even sixty bushels have been produced on a single
acre. When clover and grass seeds are sown with it, it is
recommended to delay the sowing of the grass seed, until
the barley has just appeared above the soil and then harrow
it in. This will effect the barley favorably, and increase
the*quantity of both crops.

Buckwheat is a valuable crop, because it will flourish well
on a sandy, poor soil. It is, however, but little cultivated in
New England. It is one of the best crops for turning in to
the soil to increase the quantity of vegetable matter. It will
yield, upon an average, 30 bushels per acre, and the flour is

CULTIVATION OF ROOTS. iRlp

much esteemed for making warm cakes, and brings as high
a price as wheat. It is easily cultivated, and may be sown
as late as July, but the flour is not always good.

Flax and hemp are cultivated to a very limited extent in
this country. For a particular description of their mode of
culture, the reader is referred to the agricultural publications
of the day.

Rice and cotton are also cultivated in the South, but the
methods of culture need no description in this connection.

Sect. 2. Cultivation of Roots.

The cultivated roots are the beet, carrot, turnip, potato,
parsnip, onion, etc. From their influence upon the soil, and
the small quantities of alkalies they extract, they are gene-
rally considered ameliorating crops. As many of them are
provided with broad leaves, they extract most of their nour-
ishment from the atmosphere and from water.

Potato. The potato is the bulb of the solanum tubero-
sum, and grows wild in the mountainous districts of Peru
and Chili. Potatoes are in almost universal use, and the most
valuable of root crops. In the course of cultivation, several
varieties have been produced by a treatment similar to that
pursued with corn. It is not consistent with our limits, to
treat of the different varieties and their comparative merits.
The English white, the blue, red, kidney, rohan, lady's-fin-
ger, long-red and chenango are names by which several va-
rieties are designated. As the potato is generally propagated
by eyes or the tubers, and not by the seeds, it has been a
question much discussed by farmers, whether the whole po-
tato should be planted, or only the cuttings. This question
has been very satisfactorily settled by experiment. It is
found that the seed end, or that opposite to the stalk, cut
rather deep, yields the largest and most thrifty shoots and the
most bountiful crop.*

* See experiments in Buel's Cultivator, Vol. III. p. 182.

28*

334 PRACTICAL AGRICULTURE.

The seed end is always to be prefered for several reasons.
1. The potatoes will be two weeks earlier. 2. The other
part of the potato is valuable for cooking or domestic ani-
mals. 3. The eyes next to the point where the tuber is at-
tached to the stalk, will produce only weak shoots and small
tubers. Hence, as the size of the tuber will depend upon
the seed, and size of the tuber from which the seed is taken,
we have an easy and certain rule which we may adopt, in
reference to the seed required for this crop. The quantity of
seed may vary from 10 to 20 bushels per acre.

The soil best fitted for potatoes, is a light sandy loam ; but
they will flourish well on almost any soil, especially on green
sward. For culinary purposes, the soil should be light and
dry, but of a deep tillage.

The mode of preparing the soil, is, either to turn it over
after green manure or compost has been spread over the sur-
face, or, if moist, to throw it into ridges, and plant the pota-
toes in drills or rows, about six inches apart. In the former
case, the potatoe hills may be 3 feet by 2, with 3 or 4 seed
ends in a hill. Whether potatoes should be cultivated in hills
or drills, is not well settled. It is a common practice to ma-
nure potatoes in the hills or drills, but unless there is a want
of manure, this process is not so good as that of burying the
manure deeply under the surface. Potatoes require to be
covered from 3 to 6 inches in depth, according to the mois-
ture of the soil. The after culture should be first with the
cultivator, and then with the hoe. Some recommend a flat
surface, which may succeed well, if the soil is very deep and
light ; otherwise, there should be large broad hills, in order
to give the air and water a free circulation to the roots.

The time of harvesting potatoes will depend upon their
maturity. They should be suffered to remain in the ground
until the stalk is perfectly dry. If the tubers are taken qut of
the ground before they are perfectly ripe, they will be liable
to wilt, or to become unwholesome before spring. The best

ROOT CROPS BEETS. 335

mode of securing them, is to put them in pits, into which but
a small quantity of air is admitted. When left in the ground,
they are much better in the spring than when exposed to the
air in cellars. Daubeny states, that they may be preserved
perfectly, by freezing them up solid in the fall, and thawing
them in the spring and rapidly drying them.

The following is an estimate of the value of this crop in
Massachusetts. Ploughing §4,00 per acre ; manuring in hill
$15,00 ; seed, 20 bushels, worth $5,00 ; two hoeings, $4,00,
and digging, $10,00 ; amounting in all to $38,00. The aver-
age produce is 200 bushels to the acre, worth at least $50,00.
This would give a net profit of $12,00 per acre. In some
places, the value of the crop is more than double this sum ; in
others, less than half of it. But $12,00 per acre may be re-
garded as an average profit on every acre of potatoes culti-
vated in the State.

Beets. There are several varieties of this root ; four vari-
ties, at least, are cultivated to some extent in this country.

1. Mangel Wurtzel. This is the largest, and most pro-
ductive of the family.

Fig. 20-

The soil required for this crop, is a deep, moist, clayey
loam. The tillage, as in all cases with root crops, should be
deep ; and the sub-soil plough used, to render the earth per-
meable by the roots, to the depth of 12 or 16 inches. The
seeds may be sown with a drill-barrow, (Fig. 20), and covered
with a hoe in rows about 2 feet apart, or they may be dropped

336 PRACTICAL AGRICULTURE.

by means of a dibble. This instrument is made of wood, with
a handle 3 feet long, a head like a rake, and from 6 to 12 teeth
one inch in diameter ; it is made so that it may be stamped
down, and the holes made an inch or two deep, about 2 inches
apart. A boy may then follow, and drop one seed into each
hole and cover with fine mould half an inch deep. They
should be sown the last of May. The after-culture consists
simply in keeping the ground clear of weeds, and of thinning
the plants to the distance of 8 or 10 inches. The roots
should be gathered as soon as they are ripe ; which may be
known by the under leaves becoming yellow. They may
be preserved in cellars, and fed out to farm stock.

The cost of cultivating this crop, is estimated at about
f 30,00 per acre ; and they yield, at least 600 bushels, which,
allowing a fair price for them, would leave, at least $25,00
net profit per acre.

2. The turnip and blood beet are cultivated in gardens, and
to some extent in fields. They are best cultivated in ridges;
that is, by throwing two furrows together, and sowing the
seed in double rows as above.

3. The sugar beet, or white variety, is cultivated on a lim-
ited scale in this country, but it supplies France with nearly
all her sugar.

This beet is a very profitable crop, and is beginning to be
introduced into this country. In 1841, Mr. Tudor, of Na-
hant, raised a crop which yielded at the rate of more than 36
tons to the acre, or about 1,300 bushels. The value of this
crop must be equal to $180,00 ; which is sufficient to pay all
the expense of cultivation, and leave a large profit. It should
be remarked, however, that the soil was put in the best possi-
ble condition, and in all cases, deep tillage is essential to suc-
cess. The juice of this beet is boiled into sugar, which
equals that made from sugar cane. But the chief value of
this variety in this country, is to feed out to farm stock.

Carrots are beginning to be cultivated for farm stock ;

ROOT CROPS PARSNBP. 337

theif mode of culture, is in all respects similar to that of beets ;
they require a similar soil, and the same attention to ensure a
crop. The value of carrots for field culture, is fully equal to
that of beets. They will yield about the same quantity of
food, and, for horses, are decidedly preferable to beets or any
other roots.

The value of this crop is also beginning to be estimated,
by many of our farmers. We do not see why this root is not
cultivated instead of the Swedish turnip, as we believe that
it is much more valuable for farm stock, especially for cows
which give milk.

Parsnip. The parsnip is also beginning to be cultivated
for farm stock, and requires the same treatment as beets and
carrots. Parsnips are equally productive, and much better
for some purposes. They may remain in the ground over
winter, and be fed out in the spring. On this account, they
are preferable for feeding stock late in the season. We do
not know why this root is not cultivated more extensively by
all our farmers.

Artichoke. The Jerusalem artichoke is a root which is
valuable for light sandy soils. The introduction of it among
the cultivated roots, would be of the greatest advantage to ag-
riculture. (See p. 129.)

Onion. This can hardly be regarded as a field crop, al-
though they are raised in great abundance near our cities.
Their mode of culture is well known. They require a moist
soil, and may be cultivated several years in succession on
the same field.

Turnips. The introduction of the turnip among the cul-
tivated crops, constitutes an era in the art of husbandry.
Of the several varieties which are cultivated, we may select
three, as most worthy of attention : the yellow, white and
Swedish or ruta baga turnips.

1. Ruta baga or Swedish turnip is the most important of
these varieties, and yields the largest quantity of vegetable

338 PRACTICAL AGRICULTURE.

matter for the use of farm stock. It should be remarked, al-
so, that there are varieties in this root. The best have a yel-
lowish look, globular form, and have no neck or stem. The
green and yellow kinds often prove abortive. The seed
should be black and full. One pound will suffice for an
acre of land. One half a pound will produce plants enough
for an acre ; but as the seed is liable to fail, a pound is not
too much to ensure a crop.

The time for sowing is from the 20th of June to the 5th of
July.

The soil best adapted to turnips, is a light, dry and
friable loam ; or almost any dry soil, with the exception of
heavy clays.

The soil is best prepared by throwing it into drills 8 feet
apart, filling the drills with short manure or compost, and af-
ter covering it with a plough, two furrows on each side, sow
with a drill-barrow, p. 335. The ruta baga flourishes best
on a clover ley, and may be sowed after the first crop of clo-
ver is taken. If long manure is applied, it should be covered
with a plough. If rotted, it should be placed under the seed,
so that the roots will penetrate it. The plants generally
make their appearance in 8 or 10 days after sowing ; they
should then be horse-hoed with the cultivator, and the soil
should be removed as near to the plants as possible, in order
to destroy the weeds. The hoe should then be employed,
and the plants thinned to a distance of 8 or 10 inches.

The quality of this crop depends upon the size ; and what
is rather remarkable, the larger they are the more nutriment
they possess in proportion to their weight.

Gathering. The roots may be easily drawn with the hand.
The tops and tap-roots should be cut off, and they should be
permitted to dry on the ground, until the dirt may be sepa-
rated from them. They should then be stored in pits, 3 feet
in breadth, and covered with a good thickness of earth. The
value of this crop is variously estimated by different farmers.

ROOT CROPS TURNIPS. 339

The products are, upon an average, 600 bushels per acre.
Some estimate the net profit at 80 dollars per acre ; but their
value will vary in different places and seasons. There is no
doubt but that it is one of the most valuable crops raised by
the farmer, although they are much less esteemed than they
formerly were.

Use. This root is excellent for all kinds of farm stock.
They are said to be useful for fattening hogs, cattle and sheep.
They may be fed raw, sliced, and a small quantity of salt
sprinkled over them.

2. The wliite turnip requires a similar soil and treatment ;
but may be sowed as late as the 2.5th of July. They are not
so productive as the preceding, but are excellent for a second
crop, or for feeding cattle in the fall ; by which course light
soils may be improved.

3. The yellow varieties may be sown about the 1.5th of July,
and are richer than the white. Sinclair estimates the amount
of nourishment in 64 drachms as follows.

White tankard

76grs.

Store or garden

85 grs

Common white loaf

80 "

Ruta baga

110 «

Norfolk white

73 "

The following table gives the nutritive properties of several
varieties. The green-top yellows being taken as a standard.

Species and Varieties. Siiouid weigh

by Size & Standard.

Actual Weight

Ihs. oz.

lbs. oz.

Green-top yellow

16.00

15.00

Swedish or ruta baga

11.2

13.12

Red-top yellow

12.00

12.10

Dalis hybrid

13.12

12.00

White globe

20.8

15.8

Red-top white

16.8

13.00

Green-top white

8.7

8.8

White tankard

16.

14.

Purple do.

12.10

11.8

This table shows the superiority of the ruta baga -over all
the other varieties. It yields about 6 or 7 per cent, of its
whole weight of nutritive matter, while the white varieties

340 PRACTICAL AGRICULTURE.

afford 4 per cent., and in the largest roots only 3 J per cent,
of their whole weight ; hence, one acre of the Swedish varie-
ty is equal to one and a half acres of the white. " No per-
son," says Lord Kaimes, " ever deserved better of his coun-
try, than he who first cultivated turnips in a field. No plant
contributes more to fertility."

It appears from the investigations thus far made, that roots
are by far the most profitable crops cultivated by the farmer ;
and that their more general introduction would both increase
the value of the soil, and the quantity of productions from
the farm, from the dairy and from farm stock.

Sect. 3. Cultivation of Grasses.

Grasses constitute the principal food of farm stock, and,
reciprocally, the food of future crops ; hence, their cultiva-
tion must be an important branch of agriculture in almost
every country, but especially in countries in which from 4 to
6 months of the year, the earth is destitute of herbage ; as it
is in most temperate and cold climates. The points to which
the farmer should direct his attention in the cultivation of the
grasses, are the selection of seed, and soil adapted to the
character of the plant; the preparation of the soil ; the sow-
ing of the seed ; the time and mode of securing the crop, and
its comparative value. The cultivated grasses may include
what have been called herbage plants, of which the clovers and
lucern are the only kinds* which have been cultivated in this
country.

I. Clovers. There are three species of clover, usually cul-
tivated by the farmers of this country, and two other species,
which have been cultivated in Great Britain, in which coun-
try clovers were first cultivated in the 16th century.

* Sanfoin, bird's-foot, trefoil, parsley, burret, rib-wort, plantain,
broom, wild-flower, yarrow, etc. are of this class ; but are of little im-
portance, with the exception of sanfoin, which requires a chalky soil.
The bird's-foot and trefoil have been but partially cultivated among us.

CULTIVATION OF CLOVER. 341

1. Red clover {trifolium pratense) is a well known bien-
nial, and sometimes, if not permitted to seed, a triennial plant.
It does not mature its seeds well in the first of the season,
and hence it must be fed until June, or else the seed must be
obtained from a second crop, which will ripen in August, or
the first of September.

T'he soil best adapted to red clover is a deep sandy loam.
The long tap-roots will extend downward to a great depth ;
and hence deep dry soils, of almost any description, are well
suited to it, although it prefers one in which there is a large
quantity of lime.

The quantity/ of seed depends upon the soil ; it is usually,
in this country, 10 lbs. to the acre; in Flanders, 6 lbs. ; and,
in Great Britain, 14. The greater the number of plants which
can be made to grow, the finer and better the quality of the
hay.

The time of sowing clover seed is in the spring, either with
a grain crop, and before the last harrowing or bushing, or
upon winter grain, just as the snows are leaving, in March or
April. The sowing should be followed by a light harrow or
roller. The latter especially will be of essential service to
the grain crop. If the soil is wet, or a stiff clay, the seed
should be sown in mid-summer with buckwheat. The prac-
tice of sowing clover seeds in the autumn, should be discon-
tinued, as the plant rarely attains sufficient strength to sur-
vive the frosts of winter.

During the growth of clover, the crop may be much in-
creased by sprinkling the surface of the young shoots, in the
spring, with plaster, one bushel to the acre ; and if the crop
is continued for several years, a top dressing of lime or ashes
will prove highly beneficial.

The time of cutting clover, when intended for hay, is at a

period when it is in full bloom. It is then much lighter, but

the stalks are more tender, and will fatten stock much faster,

than if permitted to remain until the seeds ripen. And fur-

29

342 PRACTICAL AGRICULTURE.

ther, two crops may be cut the same season, one for hay and
the other for seed, or both for hay.

The methods of making clover into hay are variously de-
scribed by different practical farmers. The following seems
to accord best, both with theory and the experience of the
best farmers. After the swaths are turned, they should be
spread just so that the heat of the sun will wilt and partially
dry the leaves ; the clover may then be placed in grass-cocks,
about 6 feet high, using a fork instead of a rake. By this
means the cocks may be formed with the straws all inclining
downward, so as to carry off the rain. The rake may then
pass over the ground to gather up the remainder. The cocks
should always be formed before the leaves begin to crumble,
and before the dew begins to fall. The cocks may now stand
from 36 to 48 hours, until they grow quite warm. They
should be opened after the dew is off, spread out G inches
thick, turned between 12 and 2, and, if the day is good,
gathered into the barn one or two hours afterwards. A small
quantity of salt, 3 or 4 quarts to a load, should be mingled in
the mow.

The advantages of this course have been tested by the
experience of the best farmers. The reasons for it are found
in the size of the stalk compared with the leaf. When spread,
and exposed to a hot sun, the leaves dry up to a crisp, and
fall off before the stalks are sufficiently dried to be placed in
the mow, without the danger of heating. In the cock, the
heating process commences, and all parts of the plant are
dried alike ; if fermentation is arrested at the proper time, it
will not be so liable to heat in the mow, and hence will con-
tinue green, fresh and sweet until used.

2. The C020 grass or southern clover {trifolium medium
or trifolium Pcnnsylvanicum) is a perennial, resembling the
red clover, but shorter and with paler flowers. It is a fort-
night earlier than the preceding. Hence two crops may be
cut the same season, even if fed until the 20th of June; or if

i

CULTIVATION OF LUCERNE. 343

the first crop is taken by the 28th, the second crop will mature
its seeds.

3. White clover {trifolium repens) is also a perennial and
a very sweet and useful plant ; it should be sown more fre-
quently than it is. It is mostly found in pastures and furnishes
the best of food for grazing. The yellow and scarlet clover
are not cultivated among us, though the former is in England.
Clover is admirably adapted to an alternating system of hus-
bandry, as two crops may be cut in one season. As its roots
penetrate and divide the soil and exhaust but little from it,
we are astonished that our farmers do not cultivate it more,
and are disposed to subscribe fully to the sentiment of the
Flemmings, that "no man in Flanders would pretend to call
himself a farmer without clover."

4. Lucerne {incdicago sativa) is called in this country,
French clover. It is a perennial plant, sending up several
small shoots resembling clover, but with spikes of blue or
violet flowers. It was early cultivated by the Romans, and
is now cultivated in many countries of Europe, South Ameri-
ca and the United States. The seed of lucerne is obtained
in the same manner as that of red clover, from the second
crop, and is contained in pods which are easily threshed.

The soil should be siliceous, with deep tillage and dry
sub-soil. No soil is too rich for it, and unless it is well pre-
pared by finely pulverizing it, the crop is liable to fail.
Loudon recommends trenching, but it flourishes well after
potatoes or roots of any kind, provided the manures are green
and deeply ploughed in.

The time for solving varies from the 1st to the 20th of May,
and the quantity of seed is from 15 to 20 lbs. per acre when
sowed broad-cast with rye, and 10 lbs, when sown in drills,
three feet apart, and other crops (as roots) cultivated between.

The after culture of this crop consists in harrowing, twice
a year, after the first year (if sown broad-cast), and in remov-
ing all the weeds. But if sowed in drills, it must be culti-

344 PRACTICAL AGRICULTURE.

vated with the cultivator and kept clear of weeds. Ashes,
gypsum and lime are excellent top dressings.

The time of cutting and the mode of curing, are precisely
the same as for clover, but it is fed to the best advantage in a
green state, or for the purpose o^ soiling, see p. 64. It may
be cut for this purpose from three to five times in a single
season, and the quantity cut from one acre, has been stated at
from 5 to 8 tons, in one season. The soiling of one acre is
sufficient to keep from 5 to 6 cows during the soiling season.
It is therefore an invaluable plant, where pasturage is scarce
or dear. But it is also an excellent hay, equal in all re-
spects, according to some farmers, to clover.

5. Timothy (phleum pratense) is better known in this
country as herdsgrass, and in Europe, as meadoio cats-tail.
It is a hardy, perennial plant, growing with great luxuriance
in our climate and soil. It is the principal foraging grass of
the Northern States.

The seed may be obtained by reaping the tops down from
10 to 12 inches and cutting the remainder for hay.

This grass flourishes in almost any soil, capable of cultiva-
tion, but as the seeds are small, particular care should be
taken to pulverize the soil, and to cover the seed lightly with
a bush-harrow or with the roller.

The time of sowing the seed may be, either in the spring,
with the spring grain, in the fiill with winter rye, or just be-
fore the ground thaws in the spring. It is often sown with
clover, a very improper practice, because the clover is ripe
at least two weeks earlier than the timothy. The quantity
may be from 4 to 5 lbs. to the acre, sown broad-cast.

Timothy may he cured, by spreading and cocking over
night, and should not be cut till its seeds are formed, hence
it exhausts the soil more than the clover. But the value of
this grass is increased by allowing it to remain on the ground
until the the seeds are in the milk ; still, if it is cut green,
there is a compensation in a greater amount of the after-crop,

RED TOP ORCHARD GRASS.

345

which had better be fed on the ground, than removed as
rowin,

6. Redtop {Agrostis vulgaris) is the herdsgrass of the
Middle and Southern States. It is indigenous to the soil,
perennial, and well adapted, both for pastures and meadows,
and especially for reclaiming swamps and wet or moist lands.
It springs up spontaneously, but may be sown with timothy,
and in the same way ; and, as they are ready to be cut at the
same season, they furnish the most valuable hay. The white-
top, or fowlmeadow, is said to be a variety of this species.

7. American cock's-foot or orchard-grass i^Dactylis glo-
merata) is one of the most permanent grasses. It is rather
coarse and whitish in appearance, with broad leaves, and
seed glumes resembling a cock's foot, from which it receives
its name.

This plant abounds in seeds, but they are very light, so
that two bushels are sown on an acre.

The best time and mode of sowing it, is with clover, be-
cause its growth is early and rapid, and both are fit for the
scythe at the same time. It may be cultivated and cured
in all respects as clover. But it appears best fitted to pas-
turage, both because of its rapid growth, and because it is
liable to grow coarse and harsh. Its highest value is obtain-
ed by keeping it cropped closely with sheep, but when cut
early with clover, the after growth is very abundant and of
great value; \ of its value is diminished if permitted to ripen
its seeds.

8. Tall oat-grass (^yc?m eZafzor) is placed by Mr. Taylor
and Mr. Muhlenburgh at the " head of good grasses." The
latter says, " it is the best of grasses, and the earliest for
green fodder and hay."

The seed is liable to waste if not collected in season. It

may be sown with grain crops in the spring, six pecks to the

acre, according to Sinclair, on a strong tenacious clay. But

a clover soil is well adapted to it. It appears to be better

29*

346 PRACTICAL AGRICULTURE.

adapted for pasture than for meadows. See Complete Farm-
er, p. 228.

9. Sweet-scented vernal grass, [Anthoxanthujn odoratuni),
and meadow foxtail (Alopecurus pratensis), are foreign
grasses. The former is rather scanty of herbage, and is
used for cow pastures ; and the latter, being much more
abundant in produce and nourishment, is cultivated in Eng-
land ; but both have been introduced into the neighborhood
of Boston and Philadelphia, and have now become a part of
the ordinary herbage of our meadows.

10. Ryegrass [Lolium perenne) is cultivated in Scotland,
and the north of England; "and forms the principal seed sown
with clover." There are several varieties of this grass, but
it has not as yet flourished well in our climate. It requires
a moist atmosphere, and is not considered worth cultivation,
unless in elevated and moist places. Our best farmers in
New England, prefer to sow all grass seeds, with the excep-
tion of clover, as early as possible, after the crop in Septem-
ber, and after tlie land is ploughed.*

The above are our principal grasses, but the common her-
bage of our meadows consists of several other varieties. Sev-
eral species also are cultivated in other countries, but are not
of sufficient importance to need further notice in this connec-
tion. In conclusion, we would call the attention of our far-
mers to the improvement of their swamps for natural meadows.
It can be shown, that such lands are most valuable for this
purpose, and may be made to yield a profit from twenty to
fifty dollars per acre annually.

Sect. 2. Relation of Farm Stock to the Cultivated Crops.

The subject of farm stock, is intimately related to the cul-
tivation of farm crops. The one cannot well flourish without

* vSee Fourth Report of the Agriculture of Massachusetts, p. 233.

FARM STOCK AND CULTIVATED CROPS. 347

the other. The suggestions which we would make, relate to
the mode of improving stock.

What then is the best method of improving the farm stock ?
We answer, by improving the farm crops. The thrift of farm
stock depends more upon a proper attention to the prepara-
tion of proper food, than to any other circumstance. Why
is it, that farmers must send to Saxony for sheep, to Berk-
shire for swine, to Durham or Yorkshire for cattle, and to
some other foreign country for seeds 1 simply because the
farm is not attended to, because the soils and crops are neg-
lected. There is neither the variety, quantity or quality of
products, which are necessary to improve native breeds, or to
keep up the thrift and perfection of those which are imported.
The consequence is, that the imported and improved animal
or plant will flourish for a while, but will gradually deterio-
rate, until they both sink below the native stock ; a new im-
portation must be made, and, in all such cases an extrava-
gent price paid. Is it not a just subject of reproach to New
England farmers, that they should thus be made the dupes of
speculation, with regard to their farm stock ; while they have
a soil, climate and sources of improvement, so favorable
for the rearing of stock, that they ought to be r pattern for the
rest of the world ?

It is a law of the animal and vegetable kingdoms, that neg-
lect will produce deterioration. This may not be percepti-
ble the first generation ; the second will begin to show it ; the
third still more. And in the course of ten or twelve genera-
tions, the reproductive and vital powers will be either wholly
exhausted, or require double feeding, to enable them to per-
form their oflices.

On the other hand, when the animal or the vegetable has
thus become deteriorated, proper attention will not reme-
dy the evil in a single generation. The progress of improve-
ment is slow ; and hence it is, that improved stock, and im-
proved seeds, result from a long course of careful culture. It

348 PRACTICAL AGRICULTURE.

requires at least as long, if not longer, to restore their wasted
energies, as it does to destroy them.

The great mistake with most farmers is, that they attempt
to cultivate too much land. They are not impressed with the
importance of investing capital in their farms and farm stock
for future use. They look not to a future and permanent
fertility and thrift, but to an immediate gain. The best stock
are the fattest, and of course will bring the most money in
the market ; they of course are sold off, and disposed of by
the butcher and his customers. The best hay must go to
market, for that which is inferior will keep the stock alive.
The sure remedy for these evils, is to have no inferior pro-
ductions ; and then we may hope to send our live stock and
seeds to other countries, instead of bringing theirs to our
own.

It is not intended by these remarks to dissuade farmers from
attending to the improvement of their farm stock, but simply
to point out the best mode of improvement ; and to show the
folly of attempting to retain, for any length of time, the per-
fection of any improvement in stock or crops, without at-
tending to the preparation of food for them.

The true method of improving stock, is to improve the
farm ; so as to retain any advance that is made, rather than
to be constantly running out one kind of stock, and intro-
ducing new kinds.

There is one great defect in the mode of introducing new
stock ; but one or two of a kind are first introduced. These
are deteriorated by mixing with those whose reproductive en-
ergies are weakened or exhausted. By this course, the far-
mer expects to procure a new, and better breed ! The prac-
tice of farmers in this respect, reminds us strongly of the reso-
lutions passed by the Irish court : " Resolved, that we build
a new jail. Resolved, secondly, that the new jail be made
from the old one. Resolved, thirdly, that the old jail remain
standing, till the new one is built."

HORTICULTURE. 349

Fanners resolve to make new breeds. They then resolve to
make them out of their old breeds ; and then resolve to let their
old breeds remain just as they are, until the new breeds are
formed. A far better series of resolutions would be to re-
solve, 1. to understand what their crops require; 2. to till less
land, and till it better ; 3. to furnish for their farm stock bet-
ter provisions ; and finally, retain for farm purposes the best
fodder, the best seeds, and the best stock.

We would remark, in conclusion, that there are other ani-
mals, aside from those domesticated by the farmer, which
bear an important relation to the cultivated crops ; we refer
particularly to foxes and crows; as there is in many places,
a bounty paid by the State for their destruction. It would be
far wiser policy, to expend the same bounty for their protection.
A single fox in a meadow will often save a ton of hay in one
season, by destroying the mice ; while crows, and other birds
perform an equally valuable service, by destroying seeds, worms
and insects, which would otherwise injure or destroy the crops.

CHAPTER IX.

HORTICULTURE.

Horticulture is so far a branch distinct from Agriculture,
that it has not only received a characteristic name, but is
generally treated of by writers in a separate treatise. We
should have said nothing upon the subject in this work,, but
for the fact that a few suggestions might be useful to the
common farmer, who does not make gardening a particulat
business, but wishes to understand several important processes
and principles connected with the art. It should be re-
marked, too, that the most important natural laws apply alike

350

HORTICULTURE.

to Agriculture and Horticulture ; and that a few suggestions
here, may emhrace what would require a separate book to un-
fold without such connection. It is to be hoped, therefore, that
what we may be able to say on this branch of the subject,
will not be wholly out of place, and will contribute to the ad-
vancement of an art which is every day becoming more and
more important. The subject may be treated of under the
following heads. 1. Selection of seeds, and the preservation
and improvement of races. 2. Propagation of species, by
seeds, eyes, cuttings, grafting and budding. 3. Processes of
pruning, training, potting and transplanting.

Sect. 1. Selection of Seeds, and Propagation and Improve-
ment of Races.

The quantity and quality of vegetable productions depend
as much upon the proper selection of seed, as upon any one
operation of the rural art. This is an important point for the
attention of the common farm ; but indispensable to the suc-
cess of the gardener.

I. The maturation of the seed is a vital action, and generally
proceeds without any difficulty, when plants are left to their
natural soil, climate and culture. But cultivated plants often
fail to mature their seeds; or, if they are matured, their vital
powers are weak, and they produce but sickly offspring.
The causes of sterility are,

1. The unnatural development o^ some organ near the seed
vessels, by which the nourishment designed for the seed is
withheld. Instances of this are found in the pear, pine-apple
and plantain. The nourishment goes to the fruit ; in which
case a portion of it, or of water, should be withheld, so that
the seed may receive its proportion. Hence it is, that some
plants, as the pine-apple, will only mature their seeds in a
poor soil. The tubers of potatoes often abstract nourishment
from the seed, and the seed from the tuber ; the same is true

IMPROVEMENT OF RACES. 351

of other roots. Hence, if seeds are required of such plants,
they will be much more perfect if the tubers are removed.

2. Deficiency of pullen. Some plants become so debili-
tated by cultivation, that the pollen of the stamen will not fer-
tilize the stigma of the pistil. In this case, the only remedy
is to bring pollen from some more vigorous plant, and apply
it, by artificial means ; a process only applicable to garden
plants.

3. A moist, cold atmosphere, will prevent the pollen from
being formed ; and, if formed, from being thrown upon the
stigma. The fertilizing influence takes place only when the
plant is exposed to the warm dry air. Sometimes the pres-
ence of insects is necessary to convey the pollen to the stig-
ma ; and if they are absent, sterility will follow.

4. The most frequent cause of sterility is the monstrous
condition of the floioers of many cultivated plants. The flow-
ers are nothing but modifications of the leaves ; the stamens
become florets in the course of cultivation, as always happens
in double flowers. Now it is evident, that when the stamens
are thus all changed, they cannot secrete pollen, and of course
there is nothing to fertilize the stigma. The stigma itself,
also, becomes changed. This can be remedied only by
planting, near by, the same species of plant which have either
stamens or pistils, as the case may be, and the requisite
quantity of pollen may be thus furnished.

5. Many cultivated plants are grown in a climate different
from that in which they grow naturally. The process of
watering, also, often exposes the flowers and fruit organs to
decay.

Such are some of the causes of the sterility of plants; and
it is evident, that if these and other causes do not operate
wholly to prevent seeds from ripening, they may weaken their
power of reproduction. As weak seeds will produce weak
plants, resource should be had to every means possible, to
give the highest degree of life and vigor to these indispensa-

352 HORTICULTURE.

ble bodies. Generally, the best seeds may be found by ex-
amination ; the plumpest and most completely formed should
be selected. Or they may be floated on water, and those
only selected which sink to the bottom.

But this mode is not the best possible one for garden seeds
and fruits ; for the vital principle in seeds may be increased
by removing branches or fruits that are near ; by exposing
the seed vessels to light ; and by prolonging the period of
ripening.

It is a well established law, of animals and vegetables, that
an unhealthy parent produces a diseased offspring ; the seed
will take after its parent. A vigorous parent will yield " a
healthy progeny in all their minute gradations and modifica-
tions ; hence varieties and monstrosities are matters of gene-
ration and constant reproduction." If seeds are to be sown
immediately, it is better that they should not be quite ripe;
for there are two periods in the latter part of the organization
of seeds, one before they are fully matured, when they pos-
sess the germinating power, and will flourish well if immedi-
ately sown ; and the other, when they are fully ripe, in which
case they lay up a large portion of carbon, and will not ger-
minate until some of it is abstracted by the decomposition of
water. Hence, if seeds are to be kept for any considerable
time, they should be perfectly ripe, and kept perfectly dry.
They will then preserve their vital powers entire, for a great
length of time. The vital energy differs in this respect from
1 to 17 hundred years or more, p. 42.

If seeds are to be packed up, it is best to put them in coarse
paper, enclosed in coarse canvass bags and exposed to the air,
the seeds being made perfectly dry before packing.

II. The prescrvatian of the races or varieties of plants by
seeds, involves many important laws of vegetable life, which
are of great interest to the practical gardener. This process
is applicable to all plants ; but is more important, and more

PRESERVATION OF RACES. 353

difficult in the case of annual plants, which comprise those
most cultivated by the farmer and the gardener.

It is the general law of seeds, to propagate species only to
which they belong ; hence, we cannot rely upon any par-
ticular variety of the species. There is, however, a tendency
to produce a seedling more nearly resembling the parent, than
any other variety of the species. There will, therefore, be a
majority of plants either like, or better than the parent. By
selecting these for seed the second year, and obtaining in
each successive year those most resembling the original seed,
the variety will be in time established. Every cultivated grain
has doubtless passed through successive stages of perfection
in a similar way, and a new habit has hecomo, jixed. See p. 324,

It is easy to learn how different varieties are produced ;
early or late varieties, for example. If a plant has been cul-
tivated for years in a warm, dry soil, where it ripens in 60
days, it will acquire an excitable habit ; and when sown in a
colder soil, will for a season, mature its fruit much earlier.
"The reverse will happen to an annual from a cold, wet
soil." But in both cases, if the plant be continued in the
same soil, it will change its habits ; hence, seedsmen ob-
tain seed from warm, dry soils, for their early vegetables ;
hence too, we may raise on cold lands certain crops, as barley
or Indian corn, provided the seed be procured from warm,
and dry soils. But how can these varieties be preserved
as their tendency is, to revert back to their wild state ?

1. The best mode of preserving the variety is, to transplant
the plant shortly before it goes to seed. By this means the
character of the variety will remain.

2. Another mode of preserving the variety is to cultivate
the crop so far from any other crop of the same species, that
there may be no intermixture of the pollen. This substance
is conveyed a considerable distance by the winds, and by in-
sects ; hence, seeds should not be saved from one or two in-
dividuals standing alone in a garden, as bees and other insects

30

354 HORTICULTURE.

will be more likely to introduce the pollen of the same, or
similar species from a distance.

III. Improvement of varieties or races. The remarks al-
ready made, apply to the improvement of the races or varie-
ties. A fixed improvement in the quality of the produce of a
plant, can be obtained only in two ways ; eiihex accidentally ^
or by the process of muling.

1. Accidental varieties often spring up, we know not why,
but when they occur, they indicate a change in the organ,
which is sometimes propagated in the seed. The nectarine
may thus have been produced from the peach.

2. But the most direct means of establishing new breeds or
varieties, is by a process called cross-breeding or muling;
that is, by selecting the most vigorous plants of two varieties,
and putting the pollen of the one upon the stigma of the other.
A new variety will thus be produced, which may be perpetu-
ated as above described. In this, way, nearly all our varie-
ties of squash and mellon are produced; and some of the
most gaudy and beautiful flowers which adorn our gardens.
There is no end to the different varieties which may be form-
ed by this process.

Sect. 2. Propagation hy Eyes, Cuttings, Grafting and
Budding.

The natural mode of propagating plants, is by means of
their seeds ; but, as we have seen, we cannot always rely up-
on that mode of continuing the same variety. Hence, propa-
gation by other modes has been resorted to, as the most
certain means of preserving and continuing any variety de-
sired. These modes recommend themselves to our attention
by another circumstance ; the time required to procure the
fruit from any species is much less, than when the seed is
employed.

Annual plants must be propagated by their seeds, or by their
tubers. Biennial and perennial plants, may generally be pro-

PROPAGATION BY EYES, CUTTINGS, ETC. 355

pagated in a much more expeditious manner by other modes.
Some of these methods will form the subjects of this section.

I. Propagation by eyes and buds. The propagation by
any other means than by seeds, depends upon the presence of
leaf-buds, or what are technically called '' fj/cs," which are
in reality, the rudiments of branches attached to the stem or
tuber. These eyes are capable, under certain conditions, of
producing new parts, of exactly the same nature, as those
from which they sprung.

Sometimes, as in the lily, they separate from the plant, and
take root, producing an independent plant ; at others, they
remain on the stem, and send out branches, flowers and fruit.

In theory, all plants appear capable of being propagated in
this way. But the fact is, that the vital power of buds is suf-
ficient in only a few plants, to enable us to be successful ;
only two are by this practice re-produced ; these are the
potato and the vine. The method of propagation by the
former, is too well known to need description ; that of the
latter, is as follows. The eye, with a small portion of the
stem, is commonly taken, and placed in earth, with a bot-
tom heat of 75° or 80°, in a damp atmosphere. In a short
time, it shoots upwards into a branch, and sends down roots
to establish itself in the soil. It is necessary, that a consid-
erable portion of the albumen should be planted with the eye
in this case, as the bud itself does not contain matter suffi-
cient for its development ; this, it must obtain from the stalk ;
and, if the quantity is increased, that is, if the whole vine is
buried, the sprout is much more vigorous. There are a few
cases, in which the buds are fixed in embryo upon the leaves,
so that new plants may be propagated from them, but this
mode is never resorted to in practice, unless it be in some
species of the cactus.

II. Propagation by cuttings or sUj^s is the most common
of all modes, with the exception of grafting. This process
depends upon the eyes or buds, and consists simply in cutting

356 HORTICULTURE.

off a branch, inserting it in fine mould, and subjecting it to
a moist, warm air. The roots, as well as the branches come
from the buds. This is shown by the fact, that the vine,
when it grows in a warm, damp stove, emits roots into the air
which proceed from buds. Roots, however, seem to be form-
ed by the action of the leaves ; branches are developments of
buds, and the buds are maintained by the matter in the tree.

Cuttings may be placed in fine mould in pots, and then
either subjected to a moderate hot-bed, or covered with glass
and exposed to the direct rays of the sun.

Layers are similar to cuttings, the only difference is that
they are attached to the parent branch, until the roots are
established. The branch is bent into the earth and half cut
through at the bend, and as soon as it has taken root it is
separated from the parent stalk.

Suckers are branches thrown up from the base of the plant,
and are one means of continuing and propagating the same
varieties.

Ill, Grafting and budding are operations, which consist
in causing one plant to grow upon the stock or branch of an-
other. This process differs from that of propagation by eyes
and cuttings, only in the circumstance, that in the former
case, a part of one individual, containing an eye, is inserted
into another of the same family, and the two form one unique
compound individual ; while, in the latter case, the eye is
made to send its roots down into the soil, and to derive its sup-
port from it. One process, is the inserting of an eye into
another tree, the other is, the inserting of it into the ground.
The object of these operations, is the same as that of layers,
cuttings, etc., to continue the same variety, or to improve it.
It is particularly applicable to those plants or trees (as the
apple, pear, peach, etc.) which are not easily propagated in
any other way. There are also many advantages secured,
especially in the character of the fruit.

J. Some varieties or species are nmch more hardy than

OPERATION OF GRAFTING.

357

others, and more delicate varieties may be ingrafted upon
them, and partake of their strength and vigor. Thus it is,
that many varieties of the vine are propagated ; as the most
choice kinds are found to grow better upon strong robust
stalks. So it is with some species of the pear, peach, cher-
ry, etc. The wild plum stock is prefered for the insertion
of buds. The wild apple is also prefered for setting grafts.

2. The peculiar qualities of some plants can be preserved
only by this process ; thus, for example, certain varieties of
the rose will become plain, if they are not budded into other
stalks.

3. The fruit may be obtained much earlier, and sooner, by
these processes than by any other. In fact, Mr. Knight has
succeeded in transfering the buds of one plant to another,
so as to produce fruit and flowers the same season. Fruit
trees do not require more than three years, and they often
will become fruitful the second year after being grafted.

The modes of performing these operations are various, but
with regard to the majority of fruit trees, it is a very simple
process.

Operation of grafting. The object of the
operator in this case, is to cause the branch
or graft of one tree to unite with the stock or
limb of another tree. Varieties of the same
species are united the most readily ; genera
of the same natural order come next, beyond
which the power does not extend. Thus pears
work well upon pears and quinces ; upon ap-
ples and thorns, they will grow, but not so
well ; while on plums, they cannot be made to
grow.

2. Whip grafting. This is a very common

kind of grafting (Fig. 21). "It is performed

by heading down a stock, paring one side of

it for the space of an inch bare, and then cut-

30*

21.

358 HORTICULTURE.

ting obliquely towards the pith from the upper end of the par-
ed part. The scion, f , is cut obliquely to correspond to the
part pared, d, and then a tongue made to fit into the slit in
the stock. Care should be taken to have the bark of the sci-
on exactly fitted to that of the stock, and then the scion may
be covered with a cement of rosin, beeswax and tallow, and
bound firmly together. The sap will pass up into the scion,
and its buds will develope themselves ; the prepared nutri-
ment will then descend and cover the wound where they
are united. This process is said to be far superior to the
process most common with us.

2. Crown grafting. This process con-
sists simply in heading down a stock hori-
zontally (Fig. 22), splitting it open in the
centre, h, and then cutting one, two or
more scions, a, so as to fit in exactly like a
wedge ; care being taken to have the bark
of the scion and that of the stock exactly co-
incide. The whole is then covered with
clay, or with the cement above spoken of, and
the scion is held in its place by the force
of the wood, in the same manner as a wedge. This process
often leaves too large a wound, and the parts are not always
healed over and made firm. It is, however, the most expedi*
tious way, the most simple and generally the most successful.

3. Saddle grafting. Lindley recommends Mr. Knight's
mode of saddle grafting, which, although more tedious, is
preferable to either of the preceding modes. It consists in
paring the sides of the stalk obliquely into the form of an
inverted wedge, and then cutting the scion so as to slip it di-
rectly into the stock, the bark of both exactly coinciding. By
this mode, the greatest quantity of surface is brought into con-
tact, and the sap can pass up and down with the greatest fa-
cility. The scion must be kept in its place by a ligature,
and the water excluded by cement. As the graft stands

OPERATION OF GRAFTING.

359

astride the stock, it is, when united by the wood, firm and
straight. But in all cases, success will depend upon the ex-
act coincidence of the scion and the stock, in their inner
barks and alburnum, in which the sap flows up, and the
cambium down, and where the process of assimilation takes
place.

4. Budding consists in introducing

a bud of one tree into the bark of
another. The process is as follows :
An incision is made (Fig. 23),
through the bark to the wood, and
then crossed at the top a with a simi-
lar incision. A bud is now select-
ed by paring it from the branch, tak-
ing care to cut a small quantity of
the alburnum directly under the eye,
and a portion of the bark, a. This
is then inserted below the bark of the
stock, until the bud is in contact with
the wood, and the upper lip of the wood in the stock is made
to coincide with that of the bud. The whole is then bound
by a ligature. The object in this process is, to bring in
close contact a large surface "of young organizing matter,"
and as the bud is thus freely supplied with nutriment, it soon
unites by the edges, and the following spring developes itself
in the form of a branch. The period for budding is generally
about the middle of August, or at a time when the bark will
easily peal from the stock. In selecting stocks for grafting
and buddmg, regard should be had to the soil and climate.

Sect. 3. Pruning, Training, Potting and Transplanting.

I. Pruning. The object of pruning is to remove branches
and leaves, so as to contribute to the beauty, health and pro-
ductiveness of the plant or tree.

360

HORTICULTURE.

1. The effect of removing a branch, is to turn the sap into
the neighboring organs, or into some other part ; hence it is
necessary to cut a useless branch fully off, so as to destroy the
buds near the base. If this is not done, these buds will put
forth several branches, instead of the one which is taken
away. When the nourishment is thus driven into the neigh-
boring organs, they sometimes throw out branches, which will
bear abundant fruit the next year; this is the fact with the
filbert. The peach, also, may thus be rendered both fruitful
and much longer-lived, even in climates unfavorable to its
growth. Apples, pears and plums are rendered vigorous and
strong by pruning. This effect is sometimes secured by sim-
ply squeezing the ends of the young limbs, just so as to pre-
vent their elongation, and to direct the matter to other parts,
or to the maturing of the seed. If the shoots are allowed
to increase, the buds will not form for the next crop. During
the ripening of the fruit, especially, care should be taken that
the buds and sprouts in the vicinity are removed, or twisted
to direct the nourishment to the fruit.

2. The effect produced upon one part by abstracting an-
other, is seen further in the quantity and quality of the fruit.
If all the fruit of a plant is removed from it one year, it will
be more abundant and of a better quality the next year.
Hence we see in nature, that orchards so exhaust themselves
in their season of bearing, that they are obliged to rest the
next year to recover energy for a succeeding crop. Of two
branches, if one is cut off, the other will grow with more vigor.
This doctrine lies at the foundation of all the processes of
pruning, and enables the gardener to equalize the crops and
the rate of growth of all parts of the tree. If, for example,
when orchards are disposed to bear only every other year, a
part of the fruit were abstracted in the bearing season, some
would be produced in the unfruitful season ; and, after a little
time, a habit of producing a moderate crop might be induced

REASONS FOR PRUNING. 361

and established. This, of course, vvouhi be more valuable than
one heavy crop once in two years.

The utility of trimming fruit-trees and vines when young,
depends wholly on the principle now considered.

In pruning some trees and vines, the plant is exposed to
what is called bleeding ; this, if not prevented by covering
the wounded part, will injure and perhaps destroy the plant.
One mode to avoid this, is not to wound such trees when their
sap is flowing freely. Another is, to dissolve some gum shel-
lac in alcohol, and with a brush cover the wood and prevent
the issuing of the sap.

In performing the operations of pruning, reference should
be had to the character of the tree. Some trees bear fruit on the
branch w4iich grows the same year, as the walnut. A second
class, as the filbert, grows on the wood of the previous year ;
while a third class, as pears and apples, are produced from
branches which are several years old. Hence different parts
should be removed from each of the different families.

The season for pruning is either in mid-winter or mid-sum-
mer. The object of the former method is to thin and ar-
range the branches; that of the latter, to remove superfluous
branches or aid in ripening the fruit, and in forming the fruit
of the succeeding year. It may be done at other seasons, as
early in the autumn, or when the tree is in blossom in the
spring. It should never be done when the sap first begins to
flow in the spring, because the tree wants all its leaves to
commence the process of nutrition with vigor.

It has been a question among gardeners, whether trees
which are transplanted should be pruned ? This question is
easily settled theoretically. We know that the leaves are
wanted to enable the plant to put forth its roots ; for the
nutritious matters must go through a change in the leaves,
before they descend to the roots. Now if the leaves are di-
minished by pruning, the power of the transplanted plant to
take root in the soil, is much diminished. The roots should

362 HORTICULTURE.

be trimmed rather than the branches, although no root
should be removed unless it is mutilated. If young trees,
when transplanted, are trimmed at all, it should be done in
the fall, when the quantity of nutrition laid up in them ena-
bles them to sustain such losses as they must suffer in the
process.

Root-pruning, however, may be advantageous to trees
which produce leaves rather than fruit ; and some gardeners
have thus rendered their trees fruitful.

There is a peculiar kind of pruning, called ringing, that is,
the removing of a ring of bark, at certain seasons, for the pur-
pose of stopping the sap as it descends from the leaves, and of
turning it either to the formation of fruit-buds or fruit, as the
season may be. This operation, however, although it often
increases the quantity and quality of the fruit, endangers the
/life of the tree, and is rarely resorted to. The same effect is
sometimes produced by placing a heavy stone in the fork of
the limbs. By the pressure it exerts, and by the compression
it gives to the limb, it obstructs the free circulation of sap,
and thus increases the quantity of fruit.*

II. Training is an operation wholly artificial. It has for
its object the placing of a plant in a position different from
what it could ever attain of itself, in order to gain the advan-
tage of light, heat and support. Hence plants are generally
trained or made to grow by a south wall, where the tempera-
ture is more equable, and where the winds are shut off so
that perspiration or evaporation (a frequent cause of injury)
is more equal and moderate.

1. By thus exposing a tree to a warmer atmosphere, the
sweetness of the fruit is nmch increased ; hence plums,
pears and grapes are much sweeter grown on walls with a
southern exposure.

2. By training, the circulation may be impeded, and the

* Lindk>v.

POTTING TRANSPLANTING. 363

fruit increased in quantity. Thus it is found, that when the
branches are made to grow downward, they will grow less
vigorously, but will also produce much more fruit, because
the circulation is thus impeded.

3. In the case of grapes, it is found, that the fruit is in-
creased, by training the top branches at a great distance from
the root. The tops of tall trees are more fruitful than the
side branches, owing to their distance from the roots.

The trees which are benefited by training, are such as are
properly climbers, as the grape ; but trees whose erect pos-
ture shows that they were made to be rocked by the storms,
are always injured by this process.

III. Potting is the growing of plants in small earthen ves-
sels or tubs. The condition of the roots, in this case, is dif-
ferent from that of their natural position in the soil. This
process, for most plants, is wholly unnecessary. The princi-
pal use of it is to give a start to some plants, at a period when
they cannot be placed^n other conditions. The plant will
exhaust the soil, which must be changed frequently, or they
will become sickly. If plants are placed in large tubs, they
will flourish much better and for a longer time. The cases
where potting is useful, refer to rare plants, or to those which
will not endure the frosts of winter, and to plants which are
to be transplanted. In the latter case, potting answers in-
stead of a hot-bed.

IV. Transplanting. This is an important process ; and
one in relation to which, correct practice leads to the most
useful results. A few remarks must suffice here, upon the
transplanting of trees.

These relate to the time and manner of performing the
operation. In our country, the season most desirable, is the
spring ; and during a moist or rainy day. In some coun-
tries, the fall is chosen, because the evaporation from the tree
is much less in the autumn, and early part of winter than in
the spring. But the frosts, by up-heaving the earth and the

364 HORTICULTURE.

roots, do more injury, than can arise from the different states
of the atmosphere.

It has been customary to prune trees, at the time of
transplanting ; but it is at least a very doubtful practice.
The branches contain the leaves which are necessary to pre-
pare the nutriment which is stored up in the autumn, for
assimilation. If, therefore, we cut off the branches, we di-
minish that power which is first wanted in all its force, to
meet the demands of life at this critical period.

But the most important point to be attended to in a prac-
tical way, is the preparation of the ground, and the mode of
locating the individual in its new home. For most trees, the
soil should be rendered mellow and rich, for a considerable
distance around. The pits should be made from 3 to 10
feet across, according to the size of the tree. The roots
should be left free, to extend themselves into the soil ; and
the earth around the stem should be left a little dishing, to
gather up the water that falls. It is also desirable to fill up
the pits with mould and ashes. When these conditions are
properly attended to, the tree will be, not only more thrifty at
first, but the influence will extend often through the whole
period of life.

There are many other points on the subject of horticulture,
which are important for the professional gardener ; especially
the management of green-house plants. But as these are of
little importance to the farmer, we shall here close the sub-
ject, and with it our book, with the hope, that we may at
some future period, be able to supply its present defects.

END.

INDEX.

Acid acetic, 54

apucrenic, Co, 136, 217

benzoic?, 118

crenic, (i5, 216

citric, 118

gallic, 118

humic, 65, 215

hydrochloric, 168

malic, 118

nieconic, 118

nitric, 48

oxalic, 117

phosphoric, 168, 176

prussic, 119

silicic, 167, 175, 204

sulphuric, 168, 176

tannic, 118

tartaric, 118

ulmic, 13'J
Agricultural Chemistry, 32

Geology, 32
Alkalies, 119
Albumen, 31
Aloes, 122

Alumina, 167,175,206
Aluminium, 180
Alluvial soil, 231,249
Aluminous soil, 244
Almond, 132
Ammonia, 20, 48, 80, 159
Ammoniac, 122
Amygdalin, 127
Amylaceous substances, 124
Anise, 134

Analysis of soils, 193
Animal bodies, 294
Apple thorn, 134
Aqueous rocks, 186
Argillaceous slate soil, 238
Argillaceous rock, 188
Artichoke, 129
Arrow-root, 124
Ashes, 317
Asparagus, 131
Eark, 31
Barley, 132,332
Barn-cellar, 288
Bean, small, 132

kidney., 132

Beet, 128

Beets, :i35

Belladonna, 130

Biology, 29

Bitter principle, 127

Blue dye, 120

Bones, 296

Bone-dust, 296

Brazil wood, 121

Broom- corn, 327

Buckwheat, 332

Bu*ding, 359

Buds, 44

Bulbs, 44, 129

Calcareous soil, 246

Calcareous spar, 185

Caloric, 101

Caoutchouc, 127

Calcium, 180

Cambium, 131

Carbon, 48, 138

Carbonate of magnesia, 166
potash, 166
lime, 167, 251,314
Carboniferous soils, 236
Carrot, 128, 336
Catalytic force, 45
Cattle yard, 288
Cells, 31

Cellular tissue, 30
Chalky soil, 2.'i5
Chemical affinity, 100
analysis of soils, 198
classification of soils, 242
transformations, 45
Chlorides, 319
Cinchonia, 119
Clay, 253
Clay slate soil, 237
Classification of soils, 230
Clover, 340
Cocoa-nut, 134
Coffee bean, 135
Cohesion, 99
Coloring matters, 120
Common salt, 166, 213
Compound bodies, 44
Compost of peat, 306
Conglomerate soils, 236
31

366

INDEX.

Conia or conicina, 120

Cotton, ]30

Cotyledon, 44

Cow dung, 284

Cow grass, 312

Cream of tartar, 118

Cretaceous soils, 235

Crown grafting, 358

Cubebs, 133

Cucumber, 134

Culm, 58

Cultivator, 323

Cuttings, 56

Dates, J 35

Decay, 281)

Decaying plants, 190

Diastase, ]25

Diseases of wheat, 328

Draining, 286

Drains, 258

necessity of, 260

Drill-barrow, 235

Electricity, 107

Emetina, 120

Emulsin, 126

Endosmonieter, 108

Endosmose, 108

Epidermis, 31

Epsom salts, 166
Essential salt of lemons, 118
Evaporation, 96
Excitability, 36
Exosinose, 1 JO
Extractive, 127
Extract of humus, 137
Fallow crops, 265
Feldspar, 184
Fermentation, 289
Feathers, 296
Fixed oils, 121
Flax, 130
Fox-glove, 131
Fungin, 125
Galbanum, 122
Gamboge, 122
Garlic, 129
Geates, 219

Geine,65, 138, 153,156
Gentian, 128
Germination, 49
Ginger, 129
Glacial soils, 233
Glue, 296

Gluten, 122

Gneiss, 187
soil, 246

Gooseberry, 132

Grain insect, 329

Grafting, 357

Granite, 180
soil, 240

Grapes, 132

Gravity, 98

Graywacke, 188

Green crops, 267

Growing plants, 191

Guano, 293

Gum bassora, 125
resins, 122
tragacanth, 125

Gums, 125

Hair, 295

Hartshorn, 48

Hemp, 130

Hessian fly, 329

Hog manure, 287

Hoofs, 295

Hops, 135
Hornblende, 185
rocks, 188
rock soil, 241

Horns, 295
Horse radish, 128
Horticulture, 349
Humin, 05, 135
Humus, 57, 138
Ice, 92

Igneous rocks, 1S6
Improvement of races, 350

varities, 354
Indian corn, 124,132,324
Insoluble geine, 224
Inter-cellular canals, 30
Ipecacuana, 129
Irrigation, 2()2
Irritability, 37
Iron, 180

Isatis tinctoria, 131
Isochimenal lime, 104
Ismorphism, 168
Lsotheral lime. 104
Jalap, 128

Juniper berries, 134
Lac, 121
Lava soils, 241
Layers, 56

INDEX.

367

Leached ashes, 318

Leaves, 130

Legumin, 127

Lentiles, 132

Liber, 31

Light, 105

Light carbureted hydrogen, 83

Lignin, 125

Litne, Uw, 174, 207

Limestones, \6ti

Liiuestone soil, 238

Loamy soils, 249

Log wood , 121

Lucerne, 343

Madder, 120

Magnesia, 160

Manna, 124

Magnesium, 179

Maize, 132

Manganese, 160,209

Mangel VVurtzel,335

Mango, 132

Mechinical analysis of soils, 195

Medullary rays, 31

Mica, lb4

Mica slate, 187

Mica slate soil, 239

Mildew, 329

Mixed manures, 284

Muriates, lo3

Myrrh, 122

Nails, 2115

Naked fallows, 265

Narcotina, 119

Neutral substances, 123

Nicotina. 120

Night soil, 287

Nitrate of potash, 166, 313

Nitrate of soda, 166. 313

Nitrates, 312

Nitre, 166

Nitrogen, 48,158

Nutmeg, 134 •

Oats, 132,331

Olibanum, 123

Onion, 129

Oolitic soils, 236

Opium, 123

Orange. 132

Orchard grass, 345

Organized body, 130

Organic attraction, 39

Organic affinity, 39

Organic constituents of soils, 215

Oxalate of lime, 118

Oxalate of potassa, 118

Oxides of manganese, 167

Oxygen, 47, 73

Pan II ma, 20

Parsnip, 337

Pear, 132

Peas, 132

Peat, 304

Peat alluvial soils, 232

Peaty soils, 247

Peat ashes, 318

Pepper, 132— Cayenne, 183 — Ja-

njaica, 183
Peroxide of iron, 167
Petals, 59
Phosphates, 183
Pigeons' dung, 294
Plant, 30
Plumula, 44
Pollenin, 126
Pomegranate, 129
Pond mud. 304
Pores, 31
Porphyry, 241
Potash, 166, 211,71
Potassium, 179
Potato, 333, 129
Potting, 363
Poudrette, 293
Practical agriculture, 324
Preservation of races, 352
Pressure of the air, 89
Primary soils, 237
Printers' ink, 121
Propagation by buds — by cuttings

hy eyes — by layers — by slips —

by suckers, 355, 356
Proper vessels, 30
Proximate analysis, 114
Proximate principles, 114
Pruning, 359
Putrefaction, 81, 289
Pyrites, 186, 189
Quartz, 183
Quinine, 119
Radicle, 44, 53
Rattlesnake root, 128
Red clover, 341
Red dyes, 120
Red top, 345
Resins, 122

368

INDEX.

Rhubarb, 128
Rice, 132
Rocks, J80
Roller, 'S22
Root crops, 278
Root culture, 280
Roots, J 28, 58
Rotation of crops, 271
Rotation of fields, 280
Rust, 328
Ruta baga, 337
Rye, 330, 131
Rye grass, 346
Saddle grafting, 358
Saffron, 130
Salts, 213

Saliferous soils, 236
Saline manures, 312

application of, 320
Sand, 252
Sandstones, 188
Saponin, 126
Sarsaparilla, 129
Sea weed, 303
Secondary soils, 235
Seeds, 131
Senna, 130
Serpentine, 185
Sheep manure, 287
Sienite soil, 240
Silicates, 181
Siliceous soils, 243
Silurian soils, 236
Slacked lime, 167
Slaty soil, 237
Smut, 32!)
Soda, 173, 166,213
Sodium. 179
Soil, 57'
Solan um, 120
Soluble geine, 218
Soot, 2i)7
Spent lye. 209
Spiral vessels, 31
Squills. 129
Starch. 124
Stem, 58
Strychnina, 120
Sub-soil, 58
Suckers, 56
Sugar, 123

Sulphate of iron, 319 — of lime,
of magnesia and soda, 166, 167

I Swamp muck, 304
Sweet flag, 128
Talc, ltf4
Talcose slate, 188
Talcose soil, 239
Tall oat grass, 348
Tamarinds, 133
Tapioca, 124
Tartar emetic, 118
Tea, 131

James, 131

Paraguay, 131
Tertiary soils, 234
Tillage, 66
Tissue, 30
Timothy, 344
Tobacco, 131
Trachyte soil, 241
Transplanting, 363
Trappean rocks, 188

soils, 241
Turnip, 336,339
Turnip beet, 336
Ulmin,l39

Ultimate analysis, 115
Urea, 300
Urine of the cow, 300

horse, 301

of man, 301
Utility of lime, 317
Valerian, 128
Vascular tissue, 30
Vegetable albumen, 126

mould, 65
Vinegar, 118
Vitality, nature of, 38
Vital principle, 29
Viscin, 126
Volatile oils, 122
Vortex, 30
Water, 92
Wheat, 327, 131
Whip grafting, 357
White clover, 353
White rochelle salt,
Wire- worm. 339
Wood, 31, 130
Wool, 2!'6
Yellow dye, 121
Yellow turnip, 339
Zein, 126

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