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PEAT AND ITS USES,
AS
FERTILIZER AND FUEL.
BY
SAMUEL W. JOHNSON, A. M.,
PROFESSOR OF ANALYTICAL AND AGRICULTURAL CHEMISTRY, YALE COLLEGE.
FULLY ILLUSTRATED.
NEW-YORK:
ORANGE JUDD & COMPANY.
245 BROADWAY.
Entered according to Act of Congress, in the year 1866, by
ORANGE JUDD & CO.,
At the Clerk's Office of the District Court of the United States
for the Southern District of New-York.
LOVEJOY & SON,
ELECTROTYPERS AND STEREOTYPERS
15 Vandewater street N. Y.
TO MY FATHER,
MY EARLIEST AND BEST
INSTRUCTOR IN RURAL AFFAIRS,
THIS VOLUME
IS GRATEFULLY DEDICATED.
S. W. J.
CONTENTS.
Introduction vii
PART I.--ORIGIN, VARIETIES, AND CHEMICAL CHARACTERS OF PEAT.
PAGE
1. What is Peat? 9
2. Conditions of its Formation 9
3. Different Kinds of Peat 14
Swamp Muck 17
Salt Mud 18
4. Chemical Characters and Composition of Peat 18
a. Organic or combustible part 19
Ulmic and Humic Acids 19
Ulmin and Humin--Crenic and Apocrenic Acids 20
Ulmates and Humates 21
Crenates and Apocrenates 22
Gein and Geic Acid--Elementary Composition of Peat 23
Ultimate Composition of the Constituents of Peat 25
b. Mineral Part--Ashes 25
5. Chemical Changes that occur in the Formation of Peat 26
PART II.--ON THE AGRICULTURAL USES OF PEAT AND SWAMP MUCK.
1. Characters that adapt Peat for Agricultural Use 28
A. Physical or Amending Characters 28
I. Absorbent Power for Water, as Liquid and Vapor 31
II. " " for Ammonia 32
III. Influence in Disintegrating the Soil 34
IV. Influence on the Temperature of Soils 37
B. Fertilizing Characters 38
I. Fertilizing Effects of the Organic Matters, excluding
Nitrogen 38
1. Organic Matters as Direct Food to Plants 38
2. Organic Matters as Indirect Food to Plants 40
3. Nitrogen, including Ammonia and Nitric Acid 42
II. Fertilizing Effects of the Ashes of Peat 46
III. Peculiarities in the Decay of Peat 50
IV. Comparison of Peat with Stable Manure 51
2. Characters of Peat that are detrimental, or that need
correction 54
I. Possible Bad Effects on Heavy Soils 54
II. Noxious Ingredients 55
a. Vitriol Peats 55
b. Acidity--c. Resinous Matters 57
3. Preparation of Peat for Agricultural Use 57
a. Excavation 57
b. Exposure, or Seasoning 59
c. Composting 62
Compost with Stable Manure 63
" " Night Soil 68
" " Guano 69
" " Fish and other Animal Matters 70
" " Potash-lye & Soda-ash; Wood-ashes,
Shell-marl, Lime 72
" " Salt and Lime Mixture 73
" " Carbonate of Lime, Mortar, etc 75
4. The Author's Experiments with Peat Composts 77
5. Examination of Peat with reference to its Agricultural Value 81
6. Composition of Connecticut Peats 84
Method of Analysis 86
Tables of Composition 88-89-90
PART III.--ON PEAT AS FUEL
1. Kinds of Peat that Make the Best Fuel 92
2. Density of Peat 95
3. Heating Power of Peat as Compared with Wood and Anthracite 96
4. Modes of Burning Peat 102
5. Burning of Broken Peat 103
6. Hygroscopic Water of Peat-fuel 104
7. Shrinkage 105
8. Time of Excavation and Drying 105
9. Drainage 106
10. Cutting of Peat for Fuel--a. Preparations for Cutting 107
b. Cutting by Hand; with Common Spade; German Peat Knife 108
" with Irish Slane--System employed in East
Friesland 109
c. Machines for Cutting Peat; Brosowsky's Machine; Lepreux's
Machine 113
11. Dredging of Peat 115
12. Moulding of Peat 116
13. Preparation of Peat-fuel by Machinery, etc 116
A. Condensation by Pressure 116
a. Of Fresh Peat 116
Mannhardt's Method 117
The Neustadt Method 119
b. Of Air-dried Peat--Lithuanian Process 120
c. Of Hot-dried Peat--Gwynne's Method; Exter's Method 121
Elsberg's Process 125
B. Condensation without Pressure 127
a. Of Earthy Peat 128
Challeton's Method, at Mennecy, France 128
" " Langenberg, Prussia 130
Roberts' " Pekin, N. Y. 132
Siemens' " Boeblingen, Wirtemberg 134
b. Condensation of Fibrous Peat--Weber's Method; Hot-drying 135
Gysser's Method and Machine 140
c. Condensation of Peat of all Kinds--Schlickeysen's
Machine 144
Leavitt's Peat Mill, Lexington, Mass 146
Ashcroft & Betteley's Machine 148
Versmann's Machine, Great Britain 150
Buckland's " " 151
14. Artificial Drying of Peat 152
15. Peat Coal 157
16. Metallurgical Uses of Peat 162
17. Peat as a Source of Illuminating Gas 165
18. Examination of Peat with regard to its Value as Fuel 167
INTRODUCTION.
In the years 1857 and 1858, the writer, in the capacity of Chemist to
the State Agricultural Society of Connecticut, was commissioned to make
investigations into the agricultural uses of the deposits of peat or
swamp muck which are abundant in this State; and, in 1858, he submitted
a Report to Henry A. Dyer, Esq., Corresponding Secretary of the Society,
embodying his conclusions. In the present work the valuable portions of
that Report have been recast, and, with addition of much new matter,
form Parts I. and II. The remainder of the book, relating to the
preparation and employment of peat for fuel, &c., is now for the first
time published, and is intended to give a faithful account of the
results of the experience that has been acquired in Europe, during the
last twenty-five years, in regard to the important subject of which it
treats.
The employment of peat as an amendment and absorbent for agricultural
purposes has proved to be of great advantage in New-England farming.
It is not to be doubted, that, as fuel, it will be even more valuable
than as a fertilizer. Our peat-beds, while they do not occupy so much
territory as to be an impediment and a reproach to our country, as they
have been to Ireland, are yet so abundant and so widely
distributed--occurring from the Atlantic to the Missouri, along and
above the 40th parallel, and appearing on our Eastern Coast at least as
far South as North Carolina[1]--as to present, at numberless points,
material, which, sooner or later, will serve us most usefully when other
fuel has become scarce and costly.
The high prices which coal and wood have commanded for several years
back have directed attention to peat fuel; and, such is the adventurous
character of American enterprise, it cannot be doubted that we shall
rapidly develop and improve the machinery for producing it. As has
always been the case, we shall waste a vast deal of time and money in
contriving machines that violate every principle of mechanism and of
economy; but the results of European invention furnish a safe basis from
which to set out, and we have among us the genius and the patience that
shall work out the perfect method.
It may well be urged that a good degree of caution is advisable in
entering upon the peat enterprise. In this country we have exhaustless
mines of the best coal, which can be afforded at a very low rate, with
which other fuel must compete. In Germany, where the best methods of
working peat have originated, fuel is more costly than here; and a
universal and intense economy there prevails, of which we, as a people,
have no conception.
If, as the Germans themselves admit, the peat question there is still a
nice one as regards the test of dollars and cents, it is obvious, that,
for a time, we must "hasten slowly." It is circumstances that make peat,
and gold as well, remunerative or otherwise; and these must be well
considered in each individual case. Peat is the name for a material that
varies extremely in its quality, and this quality should be investigated
carefully before going to work upon general deductions.
In my account of the various processes for working peat by machinery,
such data as I have been able to find have been given as to cost of
production. These data are however very imperfect, and not altogether
trustworthy, in direct application to American conditions. The cheapness
of labor in Europe is an item to our disadvantage in interpreting
foreign estimates. I incline to the belief that this is more than offset
among us by the quality of our labor, by the energy of our
administration, by the efficiency of our overseeing, and, especially, by
our greater skill in the adaptation of mechanical appliances. While
counselling caution, I also recommend enterprise in developing our
resources in this important particular; knowing full well, however, that
what I can say in its favor will scarcely add to the impulse already
apparent among my countrymen.
SAMUEL W. JOHNSON.
_Sheffield Scientific School_,}
_Yale College, June, 1866._ }
FOOTNOTES:
[1] The great Dismal Swamp is a grand peat bog, and doubtless other of
the swamps of the coast, as far south as Florida and the Gulf, are of
the same character.
PART I.
THE ORIGIN, VARIETIES, AND CHEMICAL CHARACTERS
OF PEAT.
1. _What is Peat?_
By the general term Peat, we understand the organic matter or vegetable
soil of bogs, swamps, beaver-meadows and salt-marshes.
It consists of substances that have resulted from the decay of many
generations of aquatic or marsh plants, as mosses, sedges, coarse
grasses, and a great variety of shrubs, mixed with more or less mineral
substances, derived from these plants, or in many cases blown or washed
in from the surrounding lands.
2. _The conditions under which Peat is formed._
In this country the production of Peat from fallen and decaying plants,
depends upon the presence of so much water as to cover or saturate the
vegetable matters, and thereby hinder the full access of air. Saturation
with water also has the effect to maintain the decaying matters at a
low temperature, and by these two causes in combination, the process of
decay is made to proceed with great slowness, and the solid products of
such slow decay, are compounds that themselves resist decay, and hence
they accumulate.
In the United States there appears to be nothing like the extensive
_moors_ or _heaths_, that abound in Ireland, Scotland, the north of
England, North Germany, Holland, and the elevated plains of Bavaria,
which are mostly level or gently sloping tracts of country, covered with
peat or turf to a depth often of 20, and sometimes of 40, or more, feet.
In this country it is only in low places, where streams become
obstructed and form swamps, or in bays and inlets on salt water, where
the flow of the tide furnishes the requisite moisture, that our
peat-beds occur. If we go north-east as far as Anticosti, Labrador, or
Newfoundland, we find true moors. In these regions have been found a few
localities of the _Heather_ (_Calluna vulgaris_), which is so
conspicuous a plant on the moors of Europe, but which is wanting in the
peat-beds of the United States.
In the countries above named, the weather is more uniform than here, the
air is more moist, and the excessive heat of our summers is scarcely
known. Such is the greater humidity of the atmosphere that the
bog-mosses,--the so-called _Sphagnums_,--which have a wonderful avidity
for moisture, (hence used for packing plants which require to be kept
moist on journeys), are able to keep fresh and in growth during the
entire summer. These mosses decay below, and throw out new vegetation
above, and thus produce a bog, especially wherever the earth is springy.
It is in this way that in those countries, moors and peat-bogs actually
grow, increasing in depth and area, from year to year, and raise
themselves above the level of the surrounding country.
Prof. Marsh informs the writer that he has seen in Ireland, near the
north-west coast, a granite hill, capped with a peat-bed, several feet
in thickness. In the Bavarian highlands similar cases have been
observed, in localities where the atmosphere and the ground are kept
moist enough for the growth of moss by the extraordinary prevalence of
fogs. Many of the European moors rise more or less above the level of
their borders towards the centre, often to a height of 10 or 20 and
sometimes of 30 feet. They are hence known in Germany as _high_ moors
(_Hochmoore_) to distinguish from the level or dishing _meadow-moors_,
(_Wiesenmoore_). The peat-producing vegetation of the former is chiefly
moss and heather, of the latter coarse grasses and sedges.
In Great Britain the reclamation of a moor is usually an expensive
operation, for which not only much draining, but actual cutting out and
burning of the compact peat is necessary.
The warmth of our summers and the dryness of our atmosphere prevent the
accumulation of peat above the highest level of the standing water of
our marshes, and so soon as the marshes are well drained, the peat
ceases to form, and in most cases the swamp may be easily converted into
good meadow land.
Springy hill-sides, which in cooler, moister climates would become
moors, here dry up in summer to such an extent that no peat can be
formed upon them.
As already observed, our peat is found in low places. In many instances
its accumulation began by the obstruction of a stream. To that
remarkable creature, the beaver, we owe many of our peat-bogs. These
animals, from time immemorial, have built their dams across rivers so as
to flood the adjacent forest. In the rich leaf-mold at the water's
verge, and in the cool shade of the standing trees, has begun the growth
of the sphagnums, sedges, and various purely aquatic plants. These in
their annual decay have shortly filled the shallow borders of the
stagnating water, and by slow encroachments, going on through many
years, they have occupied the deeper portions, aided by the trees,
which, perishing, give their fallen branches and trunks, towards
completing the work. The trees decay and fall, and become entirely
converted into peat; or, as not unfrequently happens, especially in case
of resinous woods, preserve their form, and to some extent their
soundness.
In a similar manner, ponds and lakes are encroached upon; or, if
shallow, entirely filled up by peat deposits. In the Great Forest of
Northern New York, the voyager has abundant opportunity to observe the
formation of peat-swamps, both as a result of beaver dams, and of the
filling of shallow ponds, or the narrowing of level river courses. The
formation of peat in water of some depth greatly depends upon the growth
of aquatic plants, other than those already mentioned. In our Eastern
States the most conspicuous are the Arrow-head, (_Sagittaria_); the
Pickerel Weed, (_Pontederia_;) Duck Meat, (_Lemna_;) Pond Weed,
(_Potamogeton_;) various _Polygonums_, brothers of Buckwheat and
Smart-weed; and especially the Pond Lilies, _(Nymphoea_ and _Nuphar_.)
The latter grow in water four or five feet deep, their leaves and long
stems are thick and fleshy, and their roots, which fill the oozy mud,
are often several inches in diameter. Their decaying leaves and stems,
and their huge roots, living or dead, accumulate below and gradually
raise the bed of the pond. Their living foliage which often covers the
water almost completely for acres, becomes a shelter or support for
other more delicate aquatic plants and sphagnums, which, creeping out
from the shore, may so develop as to form a floating carpet, whereon the
leaves of the neighboring wood, and dust scattered by the wind collect,
bearing down the mass, which again increases above, or is reproduced
until the water is filled to its bottom with vegetable matter.
It is not rare to find in our bogs, patches of moss of considerable area
concealing deep water with a treacherous appearance of solidity, as the
hunter and botanist have often found to their cost. In countries of more
humid atmosphere, they are more common and attain greater dimensions. In
Zealand the surfaces of ponds are so frequently covered with floating
beds of moss, often stout enough to bear a man, that they have there
received a special name "_Hangesak_." In the Russian Ural, there occur
lakes whose floating covers of moss often extend five or six feet above
the water, and are so firm that roads are made across them, and forests
of large fir-trees find support. These immense accumulations are in fact
floating moors, consisting entirely of peat, save the living vegetation
at the surface.
Sometimes these floating peat-beds, bearing trees, are separated by
winds from their connection with the shore, and become swimming peat
islands. In a small lake near Eisenach, in Central Germany, is a
swimming island of this sort. Its diameter is 40 rods, and it consists
of a felt-like mass of peat, three to five feet in depth, covered above
by sphagnums and a great variety of aquatic plants. A few birches and
dwarf firs grow in this peat, binding it together by their roots, and
when the wind blows, they act as sails, so that the island is constantly
moving about upon the lake.
On the Neusiedler lake, in Hungary, is said to float a peat island
having an area of six square miles, and on lakes of the high Mexican
Plateau are similar islands which, long ago, were converted in fruitful
gardens.
3. _The different kinds of Peat._
Very great differences in the characters of the deposits in our
peat-beds are observable. These differences are partly of color, some
peats being gray, others red, others again black; the majority, when
dry, possess a dark brown-red or snuff color. They also vary remarkably
in weight and consistency. Some are compact, destitute of fibres or
other traces of the vegetation from which they have been derived, and on
drying, shrink greatly and yield tough dense masses which burn readily,
and make an excellent fuel. Others again are light and porous, and
remain so on drying; these contain intermixed vegetable matter that is
but little advanced in the peaty decomposition. Some peats are almost
entirely free from mineral matters, and on burning, leave but a few _per
cent._ of ash, others contain considerable quantities of lime or iron,
in chemical combination, or of sand and clay that have been washed in
from the hills adjoining the swamps. As has been observed, the peat of
some swamps is mostly derived from mosses, that of others originates
largely from grasses; some contain much decayed wood and leaves, others
again are free from these.
In the same swamp we usually observe more or less of all these
differences. We find the surface peat is light and full of partly
decayed vegetation, while below, the deposits are more compact. We
commonly can trace distinct strata or layers of peat, which are often
very unlike each other in appearance and quality, and in some cases the
light and compact layers alternate so that the former are found below
the latter.
The light and porous kinds of peat appear in general to be formed in
shallow swamps or on the surface of bogs, where there is considerable
access of air to the decaying matters, while the compacter, older, riper
peats are found at a depth, and seem to have been formed beneath the
low water mark, in more complete exclusion of the atmosphere, and under
a considerable degree of pressure.
The nature of the vegetation that flourishes in a bog, has much effect
on the character of the peat. The peats chiefly derived from mosses that
have grown in the full sunlight, have a yellowish-red color in their
upper layers, which usually becomes darker as we go down, running
through all shades of brown until at a considerable depth it is black.
Peats produced principally from grasses are grayish in appearance at the
surface, being full of silvery fibres--the skeletons of the blades of
grasses and sedges, while below they are commonly black.
_Moss peat_ is more often fibrous in structure, and when dried forms
somewhat elastic masses. _Grass peat_, when taken a little below the
surface, is commonly destitute of fibres; when wet, is earthy in its
look, and dries to dense hard lumps.
Where mosses and grasses have grown together simultaneously in the same
swamp, the peat is modified in its characters accordingly. Where, as may
happen, grass succeeds moss, or moss succeeds grass, the different
layers reveal their origin by their color and texture. At considerable
depths, however, where the peat is very old, these differences nearly or
entirely disappear.
The geological character of a country is not without influence on the
kind of peat. It is only in regions where the rocks are granitic or
silicious, where, at least, the surface waters are free or nearly free
from lime, that _mosses_ make the bulk of the peat.
In limestone districts, peat is chiefly formed from _grasses_ and
_sedges_.
This is due to the fact that mosses (sphagnums) need little lime for
their growth, while the grasses require much; aquatic grasses cannot,
therefore, thrive in pure waters, and in waters containing the requisite
proportion of lime, grasses and sedges choke out the moss.
The accidental admixtures of soil often greatly affect the appearance
and value of a peat, but on the whole it would appear that its quality
is most influenced by the degree of decomposition it has been subjected
to.
In meadows and marshes, overflowed by the ocean tides, we have
_salt-peat_, formed from Sea-weeds (_Algae_,) Salt-wort (_Salicornia_,)
and a great variety of marine or strand-plants. In its upper portions,
salt-peat is coarsely fibrous from the grass roots, and dark-brown in
color. At sufficient depth it is black and destitute of fibres.
The fact that peat is fibrous in texture shows that it is of
comparatively recent formation, or that the decomposition has been
arrested before reaching its later stages. Fibrous peat is found near
the surface, and as we dig down into a very deep bed we find almost
invariably that the fibrous structure becomes less and less evident
until at a certain depth it entirely disappears.
It is not depth simply, but age or advancement in decomposition, which
determines these differences of texture.
The "ripest," most perfectly formed peat, that in which the peaty
decomposition has reached its last stage,--which, in Germany, is termed
_pitchy-peat_ or _fat peat_, (_Pechtorf_, _Specktorf_)--is dark-brown or
black in color, and comparatively heavy and dense. When moist, it is
firm, sticky and coherent almost like clay, may be cut and moulded to
any shape. Dried, it becomes hard, and on a cut or burnished surface
takes a luster like wax or pitch.
In Holland, West Friesland, Holstein, Denmark and Pomerania, a so-called
_mud-peat_ (_Schlammtorf_, also _Baggertorf_ and _Streichtorf_,) is
"fished up" from the bottoms of ponds, as a black mud or paste, which,
on drying, becomes hard and dense like the pitchy-peat.
The two varieties of peat last named are those which are most prized as
fuel in Europe.
_Vitriol peat_ is peat of any kind impregnated with sulphate of iron
(_copperas_,) and sulphate of alumina, (the astringent ingredient of
alum.)
_Swamp Muck._--In New England, the vegetable remains occurring in
swamps, etc., are commonly called _Muck_. In proper English usage, muck
is a general term for manure of any sort, and has no special application
to the contents of bogs. With us, however, this meaning appears to be
quite obsolete, though in our agricultural literature--formerly, more
than now, it must be admitted,--the word as applied to the subject of
our treatise, has been qualified as _Swamp Muck_.
In Germany, peat of whatever character, is designated by the single word
_Torf_; in France it is _Tourbe_, and of the same origin is the word
_Turf_, applied to it in Great Britain. With us turf appears never to
have had this signification.
Peat, no doubt, is a correct name for the substance which results from
the decomposition of vegetable matters under or saturated with water,
whatever its appearance or properties. There is, however, with us, an
inclination to apply this word particularly to those purer and more
compact sorts which are adapted for fuel, while to the lighter, less
decomposed or more weathered kinds, and to those which are considerably
intermixed with soil or silt, the term muck or swamp muck is given.
These distinctions are not, indeed, always observed, and, in fact, so
great is the range of variation in the quality of the substance, that it
would be impossible to draw a line where muck leaves off and peat
begins. Notwithstanding, a rough distinction is better than none, and
we shall therefore employ the two terms when any greater clearness of
meaning can be thereby conveyed.
It happens, that in New England, the number of small shallow swales,
that contain unripe or impure peat, is much greater than that of large
and deep bogs. Their contents are therefore more of the "mucky" than of
the "peaty" order, and this may partly account for New England usage in
regard to these old English words.
By the term muck, some farmers understand leaf-mold (decayed leaves),
especially that which collects in low and wet places. When the deposit
is deep and saturated with water, it may have all the essential
characters of peat. Ripe peat, from such a source is, however, so far as
the writer is informed, unknown to any extent in this country. We might
distinguish as _leaf-muck_ the leaves which have decomposed under or
saturated with water, retaining the well established term leaf-mold to
designate the dry or drier covering of the soil in a dense forest of
deciduous trees.
_Salt-mud._--In the marshes, bays, and estuaries along the sea-shore,
accumulate large quantities of fine silt, brought down by rivers or
deposited from the sea-water, which are more or less mixed with finely
divided peat or partly decomposed vegetable matters, derived largely
from Sea-weed, and in many cases also with animal remains (mussels and
other shell-fish, crabs, and myriads of minute organisms.) This black
mud has great value as a fertilizer.
4. _The Chemical Characters and Composition of Peat._
The process of burning, demonstrates that peat consists of two kinds of
substance; one of which, the larger portion, is combustible, and is
_organic_ or vegetable matter; the other, smaller portion, remaining
indestructible by fire is _inorganic matter_ or _ash_. We shall consider
these separately.
a. _The organic or combustible part of peat_ varies considerably in its
proximate composition. It is in fact an indefinite mixture of several or
perhaps of many compound bodies, whose precise nature is little known.
These bodies have received the collective names _Humus_ and _Geine_. We
shall employ the term _humus_ to designate this mixture, whether
occurring in peat, swamp-muck, salt-mud, in composts, or in the arable
soil. Its chemical characters are much the same, whatever its appearance
or mode of occurrence; and this is to be expected since it is always
formed from the same materials and under essentially similar conditions.
_Resinous_ and _Bituminous matters_.--If dry pulverized peat be agitated
and warmed for a short time with alcohol, there is usually extracted a
small amount of _resinous_ and sometimes of _bituminous_ matters, which
are of no account in the agricultural applications of peat, but have a
bearing on its value as fuel.
_Ulmic_ and _Humic acids_.--On boiling what remains from the treatment
with alcohol, with a weak solution of carbonate of soda (sal-soda), we
obtain a yellowish-brown or black liquid. This liquid contains certain
acid ingredients of the peat which become soluble by entering into
chemical combination with soda.
On adding to the solution strong vinegar, or any other strong acid,
there separates a bulky brown or black substance, which, after a time,
subsides to the bottom of the vessel as a precipitate, to use a chemical
term, leaving the liquid of a more or less yellow tinge. This deposit,
if obtained from light brown peat, is _ulmic acid_; if from black peat,
it is _humic acid_. These acids, when in the precipitated state, are
insoluble in vinegar; but when this is washed away, they are
considerably soluble in water. They are, in fact, modified by the action
of the soda, so as to acquire much greater solubility in water than they
otherwise possess. On drying the bulky bodies thus obtained, brown or
black lustrous masses result, which have much the appearance of coal.
_Ulmin_ and _Humin_.--After extracting the peat with solution of
carbonate of soda, it still contains ulmin or humin. These bodies cannot
be obtained in the pure state from peat, since they are mixed with more
or less partially decomposed vegetable matters from which they cannot be
separated without suffering chemical change. They have been procured,
however, by the action of muriatic acid on sugar. They are indifferent
in their chemical characters, are insoluble in water and in solution of
carbonate of soda; but upon heating with solution of hydrate of soda
they give dark-colored liquids, being in fact converted by this
treatment into ulmic and humic acids, respectively, with which they are
identical in composition.
The terms ulmic and humic acids do not refer each to a single compound,
but rather to a group of bodies of closely similar appearance and
properties, which, however, do differ slightly in their characteristics,
and differ also in composition by containing more or less of oxygen and
hydrogen in equal equivalents.
After complete extraction with hydrate of soda, there remains more or
less undecomposed vegetable matter, together with sand and soil, were
these contained in the peat.
_Crenic_ and _apocrenic acids_.--From the usually yellowish liquid out
of which the ulmic and humic acids have been separated, may further be
procured by appropriate chemical means, not needful to be detailed
here, two other bodies which bear the names respectively of _Crenic
Acid_ and _Apocrenic Acid_. These acids were discovered by Berzelius,
the great Swedish chemist, in the water and sediment of the Porla
spring, in Sweden.
By the action upon peat of carbonate of ammonia, which is generated to
some extent in the decay of vegetable matters and is also absorbed from
the air, ulmic and humic acids are made soluble, and combine with the
ammonia as well as with lime, oxide of iron, etc. In some cases the
ulmates and humates thus produced may be extracted from the peat by
water, and consequently occur dissolved in the water of the swamp from
which the peat is taken, giving it a yellow or brown color.
_Ulmates_ and _Humates_.--Of considerable interest to us here, are the
properties of the compounds of these acids, that may be formed in peat
when it is used as an ingredient of composts. The ulmates and humates of
the alkalies, viz.: _potash_, _soda_, and _ammonia_, dissolve readily in
water. They are formed when the alkalies or their carbonates act on
ulmin and humin, or upon ulmates or humates of lime, iron, etc. Their
dilute solutions are yellow, or brown.
The ulmates and humates of _lime_, _magnesia_, oxide of _iron_, oxide of
_manganese_ and _alumina_, are insoluble, or nearly so in water.
In ordinary soils, the earths and oxides just named, predominate over
the alkalies, and although they may contain considerable ulmic and humic
acids, water is able to extract but very minute quantities of the
latter, on account of the insolubility of the compounds they have
formed.
On the other hand, peat, highly manured garden soil, leaf-mold, rotted
manure and composts, yield yellow or brown extracts with water, from the
fact that alkalies are here present to form soluble compounds.
An important fact established by Mulder is, that when solutions of
alkali-carbonates are put in contact with the insoluble ulmates and
humates, the latter are decomposed; soluble alkali-ulmates and humates
being formed, and _in these, a portion of the otherwise insoluble
ulmates and humates dissolve_, so that thus, in a compost, lime,
magnesia, oxide of iron, and even alumina may exist in soluble
combinations, by the agency of these acids.
_Crenates_ and _Apocrenates_.--The ulmic and humic acids when separated
from their compounds, are nearly insoluble, and, so far as we know,
comparatively inert bodies; by further change, (uniting with oxygen)
they pass into or yield the crenic and apocrenic acids which, according
to Mulder, have an acid taste, being freely soluble in water, and in all
respects, decided acids. The compounds of both these acids with the
alkalies are soluble. The crenates of lime, magnesia, and protoxide of
iron are soluble, crenates of peroxide of iron and of oxide of manganese
are but very slightly soluble; crenate of alumina is insoluble. The
apocrenates of iron and manganese are slightly soluble; those of lime,
magnesia, and alumina are insoluble. All the insoluble crenates and
apocrenates, are soluble in solutions of the corresponding salts of the
alkalies.
Application of these facts will be given in subsequent paragraphs. It
may be here remarked, that the crenate of protoxide of iron is not
unfrequently formed in considerable quantity in peat-bogs, and
dissolving in the water of springs gives them a chalybeate character.
Copious springs of this kind occur at the edge of a peat-bed at
Woodstock, Conn., which are in no small repute for their medicinal
qualities, having a tonic effect from the iron they contain. Such
waters, on exposure to the air, shortly absorb oxygen, and the substance
is thereby converted into crenate and afterwards into apocrenate of
peroxide of iron, which, being but slightly soluble, or insoluble,
separates as a yellow or brown ochreous deposit along the course of the
water. By further exposure to air the organic acid is oxidized to
carbonic acid, and hydrated oxide of iron remains. Bog-iron ore appears
often to have originated in this way.
_Gein and Geic acid._--Mulder formerly believed another substance to
exist in peat which he called _Gein_, and from this by the action of
alkalies he supposed geic acid to be formed. In his later writings,
however, he expresses doubt as to the existence of such a substance,
and we may omit further notice of it, especially since, if it really
do occur, its properties are not distinct from those of humic acid.
We should not neglect to remark, however, that the word gein has been
employed by some writers in the sense in which we use humus, viz.: to
denote the brown or black products of the decomposition of vegetable
matters.
It is scarcely to be doubted that other organic compounds exist in peat.
As yet, however, we have no knowledge of any other ingredients, while it
appears certain that those we have described are its chief constituents,
and give it its peculiar properties. With regard to them it must
nevertheless be admitted, that our chemical knowledge is not entirely
satisfactory, and new investigations are urgently demanded to supply the
deficiencies of the researches so ably made by Mulder, more than twenty
years ago.
_Elementary Composition of Peat._
After this brief notice of those organic _compounds_ that have been
recognized in or produced from peat, we may give attention to the
elementary composition of peat itself.
Like that of the vegetation from which it originates, the organic part
of peat consists of Carbon, Hydrogen, Oxygen and Nitrogen. In the
subjoined table are given the proportions of these elements as found in
the combustible part of sphagnum, of several kinds of wood, and in that
of a number of peats in various stages of ripeness. They are arranged in
the order of their content of carbon.
-----------------------------------+----------+-----+-------+-----+-------
| |_Car-|_Hydro-|_Oxy-|_Nitro-
|_Analyst._|bon._| gen._ |gen._| gen._
-----------------------------------+----------+-----+-------+-----+-------
1--Sphagnum } | Websky |49.88| 6.54 |42.42| 1.16
2--Peach wood } undecomposed |Chevandier|49.90| 6.10 |43.10| 0.90
3--Poplar " } | " |50.30| 6.30 |42.40| 1.00
4--Oak " } | " |50.60| 6.00 |42.10| 1.30
5--Peat, porous, light-brown, | | | | |
sphagnous | Websky |50.86| 5.80 |42.57| 0.77
6-- " porous, red-brown. | Jaeckel |53.51| 5.90 | 40.59
7-- " heavy, brown. | " |56.43| 5.32 | 38.25
8-- " dark red-brown, | | | | |
well decomposed | Websky |59.47| 6.52 |31.51| 2.51
9-- " black, very dense | | | | |
and hard. | " |59.70| 5.70 |33.04| 1.56
10-- " black, heavy, }best quality| " |59.71| 5.27 |32.07| 2.59
11-- " brown, heavy, }for fuel. | " |62.54| 6.81 |29.24| 1.41
-----------------------------------+----------+-----+-------+-----+-------
From this table it is seen that sphagnum, and the wood of our forest
trees are very similar in composition, though not identical. Further, it
is seen from analyses 1 and 5, that in the first stages of the
conversion of sphagnum into peat--which are marked by a change of color,
but in which the form of the sphagnum is to a considerable extent
preserved--but little alteration occurs in ultimate composition; about
one _per cent._ of carbon being gained, and one of hydrogen lost. We
notice in running down the columns that as the peat becomes heavier and
darker in color, it also becomes richer in carbon and poorer in oxygen.
Hydrogen varies but slightly.
As a general statement we may say that the ripest and heaviest peat
contains 10 or 12 _per cent._ more carbon and 10 or 12 _per cent._ less
oxygen than the vegetable matter from which it is produced; while
between the unaltered vegetation and the last stage of humification, the
peat runs through an indefinite number of intermediate stages.
Nitrogen is variable, but, in general, the older peats contain the most.
To this topic we shall shortly recur, and now pass on to notice--
_The ultimate composition of the compounds of which peat consists._
Below are tabulated analyses of the organic acids of peat:--
_Carbon._ _Hydrogen._ _Oxygen._
Ulmic acid, artificial from sugar 67.10 4.20 28.70
Humic acid, from Frisian peat 61.10 4.30 34.60
Crenic acid 56.47 2.74 40.78
Apocrenic acid 45.70 4.80 49.50
It is seen that the amount of carbon diminishes from ulmic acid to
apocrenic, that of oxygen increases in the same direction and to the
same extent, viz.: about 21 _per cent._, while the hydrogen remains
nearly the same in all.
b. _The mineral part of peat, which remains as ashes_ when the organic
matters are burned away, is variable in quantity and composition.
Usually a portion of sand or soil is found in it, and this not
unfrequently constitutes its larger portion. Some peats leave on burning
much carbonate of lime; others chiefly sulphate of lime; the ash of
others again is mostly oxyd of iron; silicic, and phosphoric acids,
magnesia, potash, soda, alumina and chlorine, also occur in small
quantities in the ash of all peats.
With one exception (alumina) all these bodies are important ingredients
of agricultural plants.
In some rare instances, peats are found, which are so impregnated with
soluble sulphates of iron and alumina, as to yield these salts to water
in large quantity; and sulphate of iron (green vitriol,) has actually
been manufactured from such peats, which in consequence have been
characterized as _vitriol peats_.
Those bases (lime, oxide of iron, etc.,) which are found as carbonates
or simple oxides in the ashes, exist in the peat itself in combination
with the humic and other organic acids. When these compounds are
destroyed by burning, the bases remain united to carbonic acid.
5.--_Chemical Changes that occur in the formation of Peat._ When a plant
perishes, its conversion into humus usually begins at once. When exposed
to the atmosphere, the oxygen of the air attacks it, uniting with its
carbon producing carbonic acid gas, and with its hydrogen generating
water. This action goes on, though slowly, even at some depth under
water, because the latter dissolves oxygen from the air in small
quantity,[2] and constantly resupplies itself as rapidly as the gas is
consumed.
Whether exposed to the air or not, the organic matter suffers internal
decomposition, and portions of its elements assume the gaseous or liquid
form. We have seen that ripe peat is 10 to 12 _per cent._ richer in
carbon and equally poorer in oxygen, than the vegetable matters from
which it originates. Organic matters, in passing into peat, lose carbon
and nitrogen; but they lose oxygen more rapidly than the other two
elements, and hence the latter become relatively more abundant. The loss
of hydrogen is such that its proportion to the other elements is but
little altered.
The bodies that separate from the decomposing vegetable matter are
carbonic acid gas, carburetted hydrogen (marsh gas), nitrogen gas, and
water.
Carbonic acid is the most abundant gaseous product of the peaty
decomposition. Since it contains nearly 73 _per cent._ of oxygen and but
27 _per cent._ of carbon, it is obvious that by its escape the
proportion of carbon in the residual mass is increased. In the formation
of water from the decaying matters, 1 part of hydrogen carries off 8
parts of oxygen, and this change increases the proportion of carbon and
of hydrogen. Marsh gas consists of one part of hydrogen to three of
carbon, but it is evolved in comparatively small quantity, and hence has
no effect in diminishing the _per cent._ of carbon.
The gas that bubbles up through the water of a peat-bog, especially if
the decomposing matters at the bottom be stirred, consists largely of
marsh gas and nitrogen, often with but a small proportion of carbonic
acid. Thus Websky found in gas from a peat-bed
Carbonic acid 2.97
Marsh gas 43.36
Nitrogen 53.67
------
100.00
Carbonic acid, however, dissolves to a considerable extent in water, and
is furthermore absorbed by the living vegetation, which is not true of
marsh gas and nitrogen; hence the latter escape while the former does
not. Nitrogen escapes in the uncombined state, as it always (or usually)
does in the decay of vegetable and animal matters that contain it. Its
loss is, in general, slower than that of the other elements, and it
sometimes accumulates in the peat in considerable quantity. A small
portion of nitrogen unites with hydrogen, forming ammonia, which remains
combined with the humic and other acids.