ON PEAT AS FUEL.
1.--_Kinds of peat that make the best fuel._
The value of peat for fuel varies greatly, like its other qualities.
Only those kinds which can be cut out in the shape of coherent blocks,
or which admit of being artificially formed into firm masses, are of use
in ordinary stoves and furnaces. The powdery or friable surface peat,
which has been disintegrated by frost and exposure, is ordinarily
useless as fuel, unless it be rendered coherent by some mode of
preparation. Unripe peat which contains much undecomposed moss or grass
roots, which is therefore very light and porous, is in general too bulky
to make an effective heating material before subjection to mechanical
treatment.
The best peat for burning, is that which is most free from visible fiber
or undecomposed vegetable matters, which has therefore a homogeneous
brown or black aspect, and which is likewise free from admixture of
earthy substances in the form of sand or clay. Such peat is unctuous
when moist, shrinks greatly on drying, and forms hard and heavy masses
when dry. It is usually found at a considerable depth, where it has been
subjected to pressure, and then has such consistence as to admit of
cutting out in blocks; or it may exist as a black mud or paste at the
bottom of bogs and sluices.
The value of peat as fuel stands in direct ratio to its content of
carbon. We have seen that this ranges from 51 to 63 _per cent. of the
organic matter_, and the increase of carbon is related to its ripeness
and density. The poorest, youngest peat, has the same proportion of
carbon as exists in wood. It does not, however, follow that its heating
power is the same. The various kinds of wood have essentially the same
proportion of carbon, but their heating power is very different. The
close textured woods--those which weigh the most per cord--make the best
fuel for most purposes. We know, that a cord of hickory will produce
twice as much heat as a cord of bass-wood. Peat, though having the same
or a greater proportion of carbon, is generally inferior to wood on
account of its occupying a greater bulk for a given weight, a necessary
result of its porosity. The best qualities of peat, or poor kinds
artificially condensed, may, on the other hand, equal or exceed wood in
heating power, bulk for bulk. One reason that peat is, in general,
inferior to wood in heating effect, lies in its greater content of
incombustible ash. Wood has but 0.5 to 1.5 _per cent._ of mineral
matters, while peat contains usually 5 to 10 _per cent._, and often
more. The oldest, ripest peats are those which contain the most carbon,
and have at the same time the greatest compactness. From these two
circumstances they make the best fuel.
It thus appears that peat which is light, loose in structure, and much
mixed with clay or sand, is a poor or very poor article for producing
heat: while a dense pure peat is very good.
A great drawback to the usefulness of most kinds of peat-fuel, lies in
their great friability. This property renders them unable to endure
transportation. The blocks of peat which are commonly used in most parts
of Germany as fuel, break and crumble in handling, so that they cannot
be carried far without great waste. Besides, when put into a stove,
there can only go on a slow smouldering combustion as would happen in
cut tobacco or saw-dust. A free-burning fuel must exist in compact lumps
or blocks, which so retain their form and solidity, as to admit of a
rapid draught of air through the burning mass.
The bulkiness of ordinary peat fuel, as compared with hard wood, and
especially with coal, likewise renders transportation costly, especially
by water, where freights are charged by bulk and not by weight, and
renders storage an item of great expense.
The chief value of that peat fuel, which is simply cut from the bog, and
dried without artificial condensation, must be for the domestic use of
the farmer or villager who owns a supply of it not far from his
dwelling, and can employ his own time in getting it out. Though worth
perhaps much less cord for cord when dry than hard wood, it may be
cheaper for home consumption than fuel brought from a distance.
Various processes have been devised for preparing peat, with a view to
bringing it into a condition of density and toughness, sufficient to
obviate its usual faults, and make it compare with wood or even with
coal in heating power.
The efforts in this direction have met with abundant success as regards
producing a good fuel. In many cases, however, the cost of preparation
has been too great to warrant the general adoption of these processes.
We shall recur to this subject on a subsequent page, and give an
account of the methods that have been proposed or employed for the
manufacture of condensed peat fuel.
2.--_Density of Peat._
The apparent[10] specific gravity of peat in the air-dry state, ranges
from 0.11 to 1.03. In other words, a full cubic foot weighs from
one-tenth as much as, to slightly more than a cubic foot of water, =
62-1/3 lbs. Peat, which has a specific gravity of but 0.25, may be and
is employed as fuel. A full cubic foot of it will weigh about 16 lbs. In
Germany, the cubic foot of "good ordinary peat" in blocks,[11] ranges
from 15 to 25 lbs. in weight, and is employed for domestic purposes. The
heavier peat, weighing 30 or more lbs. per cubic foot in blocks, is used
for manufacturing and metallurgical purposes, and for firing
locomotives.
Karmarsch has carefully investigated more than 100 peats belonging to
the kingdom of Hanover, with reference to their heating effect. He
classifies them as follows:--
A. _Turfy peat_, (_Rasentorf_,) consisting of slightly decomposed mosses
and other peat-producing plants, having a yellow or yellowish-brown
color, very soft, spongy and elastic, sp. gr. 0.11 to 0.26, the full
English cubic foot weighing from 7 to 16 lbs.
B. _Fibrous peat_, unripe peat, which is brown or black in color, less
elastic than turfy peat, the fibres either of moss, grass, roots,
leaves, or wood, distinguishable by the eye, but brittle, and easily
broken; sp. gr. 0.24 to 0.67, the weight of a full cubic foot being from
15 to 42 lbs.
C. _Earthy peat._--Nearly or altogether destitute of fibrous structure,
drying to earth-like masses which break with more or less difficulty,
giving lustreless surfaces of fracture; sp. gr. 0.41 to 0.90, the full
cubic foot weighing, accordingly, from 25 to 56 lbs.
D. _Pitchy peat_, (_Pechtorf_,) dense; when dry, hard; often resisting
the blows of a hammer, breaking with a smooth, sometimes lustrous
fracture, into sharp-angled pieces. Sp. gr. 0.62 to 1.03, the full cubic
foot weighing from 38 to 55 lbs.
In Kane and Sullivan's examination of 27 kinds of Irish peat, the
specific gravities ranged from 0.274 to 1.058.
3.--_Heating power of peat as compared with wood and anthracite._
Karmarsch found that in absolute heating effect
100 lbs. of turfy, air-dry peat, on the average = 95 lbs. of pine wood.
" fibrous " " " = 108 " "
" earthy " " " = 104 " "
" pitchy " " " = 111 " "
The comparison of heating power by bulk, instead of weight, is as
follows:--
100 cubic ft. of turfy peat, on the average[12] = 33 cubic ft. of pine
wood, in sticks.
" " fibrous " " = 90 cubic ft. of pine
wood, in sticks.
" " earthy " " = 145 cubic ft. of pine
wood, in sticks.
" " pitchy " " = 184 cubic ft. of pine
wood, in sticks.
According to Brix, the weight per English cord and relative heating
effect of several air-dry peats--the heating power of an equal bulk of
oak wood being taken at 100 as a standard--are as follows, _bulk for
bulk_:[13]
_Weight per _Heating
cord._ effect._
Oak wood 4150 lbs. 100
Peat from Linum, 1st quality, dense and pitchy 3400 " 70
" " 2d " fibrous 2900 " 55
" " 3d " turfy 2270 " 53
Peat from Buechsenfeld, 1st quality, pitchy,
very hard and heavy 3400 lbs. 74
Peat from Buechsenfeld, 2d quality 2730 " 64
These statements agree in showing, that, while weight for weight, the
ordinary qualities of peat do not differ much from wood in heating
power; the heating effect of _equal bulks_ of this fuel, as found in
commerce, may vary extremely, ranging from one-half to three quarters
that of oak wood.
Condensed peat may be prepared by machinery, which will weigh more than
hard wood, bulk for bulk, and whose heating power will therefore exceed
that of wood.
Gysser gives the following comparisons of a good peat with various
German woods and charcoals, equal weights being employed, and split
beech wood, air-dry, assumed as the standard.[14]
Beech wood, split, air dry 1.00
Peat, condensed by Weber's & Gysser's method,[15] air-dried,
with 25 _per cent._ moisture. 1.00
Peat, condensed by Weber's & Gysser's method, hot-dried,
with 10 _per cent._ moisture. 1.48
Peat-charcoal, from condensed peat. 1.73
The same peat, simply cut and air-dried. 0.80
Beech-charcoal. 1.90
Summer-oak wood. 1.18
Birch wood. 0.95
White pine wood. 0.72
Alder. 0.65
Linden. 0.65
Red pine. 0.61
Poplar. 0.50
Some experiments have been made in this country on the value of peat as
fuel. One was tried on the N. Y. Central Railroad, Jan. 3, 1866. A
locomotive with 25 empty freight cars attached, was propelled from
Syracuse westward--the day being cold and the wind ahead--at the rate of
16 miles the hour. The engineer reported that "the peat gave us as much
steam as wood, and burnt a beautiful fire." The peat, we infer, was cut
and prepared near Syracuse, N. Y.
In one of the pumping houses of the Nassau Water Department of the City
of Brooklyn, an experiment has been made for the purpose of comparing
peat with anthracite, for the results of which I am indebted to the
courtesy of Moses Lane, Esq., Chief Engineer of the Department.
Fire was started under a steam boiler with wood. When steam was up, the
peat was burned--its quantity being 1743 lbs., or 18 barrels--and after
it was consumed, the firing was continued with coal. The pressure of
steam was kept as nearly uniform as possible throughout the trial, and
it was found that with 1743 lbs. of peat the engine made 2735
revolutions, while with 1100 lbs. of coal it made 3866 revolutions. In
other words, 100 lbs. of coal produced 351-45/100 revolutions, and 100
lbs. of peat produced 156-91/100 revolutions. One pound of coal
therefore equalled 2-24/100 lbs. of peat in heating effect. The peat
burned well and generated steam freely.
Mr. Lane could not designate the quality of the peat, not having been
able to witness the experiment.
These trials have not, indeed, all the precision needful to fix with
accuracy the comparative heating effect of the fuels employed; for a
furnace, that is adapted for wood, is not necessarily suited to peat,
and a coal grate must have a construction unlike that which is proper
for a peat fire; nevertheless they exhibit the relative merits of wood,
peat, and anthracite, with sufficient closeness for most practical
purposes.
Two considerations would prevent the use of ordinary cut peat in large
works, even could two and one-fourth tons of it be afforded at the same
price as one ton of coal. The Nassau Water Department consumes 20,000
tons of coal yearly, the handling of which is a large expense, six
firemen being employed to feed the furnaces. To generate the same amount
of steam with peat of the quality experimented with, would require the
force of firemen to be considerably increased. Again, it would be
necessary to lay in, under cover, a large stock of fuel during the
summer, for use in winter, when peat cannot be raised. Since a barrel of
this peat weighed less than 100 lbs., the short ton would occupy the
volume of 20 barrels; as is well known, a ton of anthracite can be put
into 8 barrels. A given weight of peat therefore requires 2-1/2 times as
much storage room, as the same weight of coal. As 2-1/4 tons of peat, in
the case we are considering, are equivalent to but one ton of coal in
heating effect, the winter's supply of peat fuel would occupy 5-5/8
times the bulk of the same supply in coal, admitting that the unoccupied
or air-space in a pile of peat is the same as in a heap of coal. In
fact, the calculation would really turn out still more to the
disadvantage of peat, because the air-space in a bin of peat is greater
than in one of coal, and coal can be excavated for at least two months
more of the year than peat.
It is asserted by some, that, because peat can be condensed so as to
approach anthracite in specific gravity, it must, in the same ratio,
approach the latter in heating power. Its effective heating power is,
indeed, considerably augmented by condensation, but no mechanical
treatment can increase its percentage of carbon or otherwise alter its
chemical composition; hence it must forever remain inferior to
anthracite.
The composition and density of the best condensed peat is compared with
that of hard wood and anthracite in the following statement:--
_In 100 _Carbon._ _Hydrogen._ _Oxygen and _Ash._ _Water._ _Specific
parts._ Nitrogen._ Gravity._
Wood, 39.6 4.8 34.8 0.8 20.0 0.75
Condensed
peat 47.2 4.9 22.9 5.0 20.0 1.20
Anthracite 91.3 2.9 2.8 3.0 1.40
In combustion in ordinary fires, the _water_ of the fuel is a source of
waste, since it consumes heat in acquiring the state of vapor. This is
well seen in the comparison of the same kind of peat in different states
of dryness. Thus, in the table of Gysser, (page 97) Weber's condensed
peat, containing 10 _per cent._ of moisture, surpasses in heating effect
that containing 25 _per cent._ of moisture, by nearly one-half.
The _oxygen_ is a source of waste, for heat as developed from fuel, is
chiefly a result of the chemical union of atmospheric or free oxygen,
with the carbon and hydrogen of the combustible. The oxygen of the fuel,
being already combined with carbon and hydrogen, not only cannot itself
contribute to the generation of heat, but neutralizes the heating effect
of those portions of the carbon and hydrogen of the fuel with which it
remains in combination. The quantity of heating effect thus destroyed,
cannot, however, be calculated with certainty, because physical changes,
viz: the conversion of solids into gases, not to speak of secondary
chemical transformations, whose influence cannot be estimated, enter
into the computation.
_Nitrogen_ and ash are practically indifferent in the burning process,
and simply impair the heating value of fuel in as far as they occupy
space in it and make a portion of its weight, to the exclusion of
combustible matter.
Again, as regards density, peat is, in general, considerably inferior to
anthracite. The best uncondensed peat has a specific gravity of 0.90.
Condensed peat usually does not exceed 1.1. Sometimes it is made of sp.
gr. 1.3. Assertions to the effect of its acquiring a density of 1.8, can
hardly be credited of pure peat, though a considerable admixture of sand
or clay might give such a result.
The comparative heating power of fuels is ascertained by burning them in
an apparatus, so constructed, that the heat generated shall expend
itself in evaporating or raising the temperature of a known quantity of
water.
_The amount of heat that will raise the temperature of one gramme of
water, one degree of the centigrade thermometer, is agreed upon as the
unit of heat._[16]
In the complete combustion of carbon in the form of charcoal or
gas-coal, there are developed 8060 units of heat. In the combustion of
one gramme of hydrogen gas, 34,210 units of heat are generated. The
heating effect of hydrogen is therefore 4.2 times greater than that of
carbon. It was long supposed that the heating effect of compound
combustibles could be calculated from their elementary composition. This
view is proved to be erroneous, and direct experiment is the only
satisfactory means of getting at the truth in this respect.
The data of Karmarsch, Brix, and Gysser, already given, were obtained by
the experimental method. They were, however, made mostly on a small
scale, and, in some cases, without due regard to the peculiar
requirements of the different kinds of fuel, as regards fire space,
draught, etc. They can only be regarded as approximations to the truth,
and have simply a comparative value, which is, however, sufficient for
ordinary purposes.
The general results of the investigations hitherto made on all the
common kinds of fuel, are given in the subjoined statement. The
comparison is made in units of heat, and refers to equal weights of the
materials experimented with.
HEATING POWER OF DIFFERENT KINDS OF FUEL.
Air-dry Wood 2800
" Peat 2500 3000
Perfectly dry Wood 3600
" " Peat 3000 4000
Air-dry Lignite or Brown Coal 3300 4200
Perfectly dry Lignite or Brown Coal 4000 5000
Bituminous Coal 3800 7000
Anthracite 7500
Wood Charcoal 6300 7500
Coke 6500 7600
4.--_Modes of Burning Peat._
In the employment of peat fuel, regard must be had to its shape and
bulk. Commonly, peat is cut or moulded into blocks or sods like bricks,
which have a length of 8 to 18 inches; a breadth of 4 to 6 inches, and a
thickness of 1-1/2 to 3 inches. Machine peat is sometimes formed into
circular disks of 2 to 3 inches diameter, and 1 to 2 inches thickness
and thereabouts. It is made also in the shape of balls of 2 to 3 inches
diameter. Another form is that of thick-walled pipes, 2 to 3 inches in
diameter, a foot or more long, and with a bore of one-half inch.
Flat blocks are apt to lie closely together in the fire, and obstruct
the draft. A fire-place, constructed properly for burning them, should
be shallow, not admitting of more than two or three layers being
superposed. According to the bulkiness of the peat, the fire-place
should be roomy, as regards length and breadth.
Fibrous and easily crumbling peat is usually burned upon a hearth, _i.
e._ without a grate, either in stoves or open fire-places. Dense peat
burns best upon a grate, the bars of which should be thin and near
together, so that the air have access to every part of the fuel. The
denser and tougher the peat, and the more its shape corresponds with
that usual to coal, the better is it adapted for use in our ordinary
coal stoves and furnaces.
5.--_Burning of broken peat._
[Illustration: Fig. 1--STAIR GRATE.]
Broken peat--the fragments and waste of the cut or moulded blocks, and
peat as obtained by plowing and harrowing the surface of drained
peat-beds--may be used to advantage in the _stair grate_, fig. 1, which
was introduced some years ago in Austria, and is adapted exclusively for
burning finely divided fuel. It consists of a series of thin iron bars 3
to 4 inches wide, _a_, _a_, _a_, ... which are arranged above each other
like steps, as shown in the figure. They are usually half as long as the
grate is wide, and are supported at each end by two side pieces or
walls, _l._ Below, the grate is closed by a heavy iron plate. The fuel
is placed in the hopper _A_, which is kept filled, and from which it
falls down the incline as rapidly as it is consumed. The air enters from
the space _G_, and is regulated by doors, not shown in the cut, which
open into it. The masonry is supported at _u_, by a hollow iron beam.
Below, a lateral opening serves for clearing out the ashes. The effect
of the fire depends upon the width of the throat of the hopper at _u_,
which regulates the supply of fuel to the grate, and upon the
inclination of the latter. The throat is usually from 6 to 8 inches
wide, according to the nature of the fuel. The inclination of the grate
is 40 to 45 deg. and, in general, should be that which is assumed by the
sides of a pile of the fuel to be burned, when it is thrown up into a
heap. This grate ensures complete combustion of fuel that would fall
through ordinary grates, and that would merely smoulder upon a hearth.
The fire admits of easy regulation, the ashes may be removed and the
fuel may be supplied without _checking the fire_. Not only broken peat,
but coal dust, saw dust, wood turnings and the like may be burned on
this grate. The figure represents it as adapted to a steam boiler.
6.--_Hygroscopic water of peat fuel._
The quantity of water retained by air-dried peat appears to be the same
as exists in air-dried wood, viz., about 20 _per cent._ The proportion
will vary however according to the time of seasoning. In thoroughly
seasoned wood or peat, it may be but 15 _per cent._; while in the poorly
dried material it may amount to 25 or more _per cent._ When _hot-dried_,
the proportion of water may be reduced to 10 _per cent._, or less.
When peat is still moist, it gathers water rapidly from damp air, and in
this condition has been known to burst the sheds in which it was stored,
but after becoming dry to the eye and feel, it is but little affected by
dampness, no more so, it appears, than seasoned wood.
7.--_Shrinkage._
In estimating the value and cost of peat fuel, it must be remembered
that peat shrinks greatly in drying, so that three to five cords of
fresh peat yield but one cord of dry peat. When the fiber of the peat is
broken by the hand, or by machinery, the shrinkage is often much
greater, and may sometimes amount to seven-eighths of the original
volume.--_Dingler's Journal, Oct. 1864_, _S._ 68.
The difference in weight between fresh and dry peat is even greater.
Fibrous peat, fresh from the bog, may contain ninety _per cent._ of
water, of which seventy _per cent._ must evaporate before it can be
called dry. The proportion of water in earthy or pitchy peat is indeed
less; but the quantity is always large, so that from five to nine
hundred weight of fresh peat must be lifted in order to make one hundred
weight of dry fuel.
8.--_Time of excavation, and drying._
Peat which is intended to be used after simply drying, must be excavated
so early in the season that it shall become dry before frosty weather
arrives: because, if frozen when wet, its coherence is destroyed, and on
thawing it falls to a powder useless for fuel.
Peat must be dried with certain precautions. If a block of fresh peat be
exposed to hot sunshine, it dries and shrinks on the surface much more
rapidly than within: as a consequence it cracks, loses its coherence,
and the block is easily broken, or of itself falls to pieces. In Europe,
it is indeed customary to dry peat without shelter, the loss by too
rapid drying not being greater than the expense of building and
maintaining drying sheds. There however the sun is not as intense, nor
the air nearly so dry, as it is here. Even there, the occurrence of an
unusually hot summer, causes great loss. In our climate, some shelter
would be commonly essential unless the peat be dug early in the spring,
so as to lose the larger share of its water before the hot weather; or,
as would be best of all, in the autumn late enough to escape the heat,
but early enough to ensure such dryness as would prevent damage by
frost. The peculiarities of climate must decide the time of excavating
and the question of shelter.
The point in drying peat is to make it lose its water gradually and
regularly, so that the inside of each block shall dry nearly as fast as
the outside.
Some of the methods of hot-drying peat, will be subsequently noticed.
Summer or fall digging would be always advantageous on account of the
swamps being then most free from water. In Bavaria, peat is dug mostly
in July and the first half of August.
9.--_Drainage._
When it is intended to raise peat fuel _in the form of blocks_, the bog
should be drained no more rapidly than it is excavated. Peat, which is
to be worth cutting in the spring, must be covered with water during the
winter, else it is pulverized by the frost. So, too, it must be
protected against drying away and losing its coherency in summer, by
being kept sufficiently impregnated with water.
In case an extensive bog is to be drained to facilitate the cutting out
of the peat for use as fuel, the canals that carry off the water from
the parts which are excavating, should be so constructed, that on the
approach of cold weather, the remaining peat may be flooded again to the
usual height.
In most of the smaller swamps, systematic draining is unnecessary, the
water drying away in summer enough to admit of easy working.
In some methods of preparing or condensing peat by machinery, it is best
or even needful to drain and air-dry the peat, preliminary to working.
By draining, the peat settles, especially on the borders of the ditches,
several inches, or even feet, according to its nature and depth. It thus
becomes capable of bearing teams and machinery, and its density is very
considerably augmented.
10.--_The Cutting of Peat._--a. _Preparations._
In preparing to raise peat fuel from the bog, the surface material,
which from the action of frost and sun has been pulverized to "muck," or
which otherwise is full of roots and undecomposed matters, must be
removed usually to the depth of 12 to 18 inches. It is only those
portions of the peat which have never frozen nor become dry, and are
free from coarse fibers of recent vegetation, that can be cut for fuel.
Peat fuel must be brought into the form of blocks or masses of such size
and shape as to adapt them to use in our common stoves and furnaces.
Commonly, the peat is of such consistence in its native bed, that it may
be cut out with a spade or appropriate tool into blocks having more or
less coherence. Sometimes it is needful to take away the surplus water
from the bog, and allow the peat to settle and drain a while before it
can be cut to advantage.
When a bog is to be opened, a deep ditch is run from an outlet or lowest
point a short distance into the peat bed, and the working goes on from
the banks of this ditch. It is important that system be followed in
raising the peat, or there will be great waste of fuel and of labor.
If, as often happens, the peat is so soft in the wet season as to break
on the vertical walls of a ditch and fill it, at the same time
dislocating the mass and spoiling it for cutting, it is best to carry
down the ditch in terraces, making it wide above and narrow at the
bottom.
b. _Cutting by hand._
The simplest mode of procedure, consists in laying off a "field" or plot
of, say 20 feet square, and making vertical cuts with a sharp spade
three or four inches deep from end to end in parallel lines, as far
apart as it is proposed to make the breadth of the peats or sods,
usually four to five inches. Then, the field is cut in a similar manner
in lines at right angles to the first, and at a distance that shall be
the length of the peats, say 18 to 20 inches. Finally, the workman lifts
the peats by horizontal thrusts of his spade, made at a depth of three
inches. The sods as lifted, are placed on a light barrow or upon a board
or rack, and are carried off to a drying ground, near at hand, where
they are laid down flatwise to drain and dry. In Ireland, it is the
custom, after the peats have lain thus for a fortnight or so, to "foot"
them, i. e. to place them on end close together; after further drying
the "footing" is succeeded by "clamping," which is building the sods up
into stacks of about twelve to fifteen feet long, four feet wide at
bottom, narrowing to one foot at top, with a height of four to five
feet. The outer turfs are inclined so as to shed the rain. The peat
often remains in these clamps on the bog until wanted for use, though in
rainy seasons the loss by crumbling is considerable.
[Illustration: Fig. 2.--GERMAN PEAT-KNIFE.]
Other modes of lifting peat, require tools of particular construction....
In Germany it is common to excavate by _vertical_ thrusts of the tool,
the cutting part of which is represented above, fig. 2. This tool is
pressed down into the peat to a depth corresponding to the thickness of
the required block: its three edges cut as many sides of the block, and
the bottom is then broken or torn out by a prying motion.
In other cases, this or a similar tool is forced down by help of the
foot as deeply into the peat as possible by a workman standing above,
while a second man in the ditch cuts out the blocks of proper thickness
by means of a sharp spade thrust horizontally. When the peats are taken
out to the depth of the first vertical cutting, the knife is used again
from above, and the process is thus continued as before, until the
bottom of the peat or the desired depth is reached.
In Ireland, is employed the "slane," a common form of which is shown in
fig. 3, it being a long, narrow and sharp spade, 20 inches by six, with
a wing at right angles to the blade.
[Illustration: Fig. 3.--IRISH SLANE.]
The peats are cut by one thrust of this instrument which is worked by
the arms alone. After a vertical cut is made by a spade, in a line at
right angles to a bank of peat, the slane cuts the bottom and other side
of the block; while at the end the latter is simply lifted or broken
away.
Peat is most easily cut in a vertical direction, but when, as often
happens, it is made up of layers, the sods are likely to break apart
where these join. Horizontal cutting is therefore best for stratified
peat.
_System employed in East Friesland._--In raising peat, great waste both
of labor and of fuel may easily occur as the result of random and
unsystematic methods of working. For this reason, the mode of cutting
peat, followed in the extensive moors of East Friesland, is worthy of
particular description. There, the business is pursued systematically on
a plan, which, it is claimed, long experience[17] has developed to such
perfection that the utmost economy of time and labor is attained. The
cost of producing marketable peat in East Friesland in 1860, was one
silver groschen=about 2-1/2 cents, per hundred weight; while at that
time, in Bavaria, the hundred weight cost three times as much when fit
for market; and this, notwithstanding living and labor are much cheaper
in the latter country.
The method to be described, presupposes that the workmen are not
hindered by water, which, in most cases, can be easily removed from the
high-moors of the region. The peat is worked in long stretches of 10
feet in width, and 100 to 1000 paces in length: each stretch or plot is
excavated at once to a considerable depth and to its full width. Each
successive year the excavation is widened by 10 feet, its length
remaining the same. Sometimes, unusual demand leads to more rapid
working; but the width of 10 feet is adhered to for each cutting, and,
on account of the labor of carrying the peats, it is preferred to extend
the length rather than the width.
Assuming that the peat bed has been opened by a previous cutting, to the
depth of 5-1/2 feet, and the surface muck and light peat, 1-1/2 feet
thick, have been thrown into the excavation of the year before--a new
plot is worked by five men as follows.
One man, the "Bunker," removes from the surface, about two inches of
peat, disintegrated by the winter's frost, throwing it into last year's
ditch.
Following him, come two "Diggers," of whom one stands on the surface of
the peat, and with a heavy, long handled tool, cuts out the sides and
end of the blocks, which are about seventeen by five inches; while the
other stands in the ditch, and by horizontal thrusts of a light, sharp
spade, removes the sods, each of five and a half inches thickness, and
places them on a small board near by. Each block of peat has the
dimensions of one fourth of a cubic foot, and weighs about 13 pounds.
Two good workmen will raise 25 such peats, or 6-1/4 cubic feet, per
minute.
A fourth man, the "Loader," puts the sods upon a wheel-barrow, always
two rows of six each, one upon the other, and--
A fifth, the "Wheeler," removes the load to the drying ground, and with
some help from the Bunker, disposes them flatwise in rows of 16 sods
wide, which run at right angles to the ditch, and, beginning at a little
more than 10 feet from the latter, extend 50 feet.
The space of 10 feet between the plot that is excavating, and the drying
ground, is, at the same time, cleared of the useless surface muck by the
Bunker, in preparation for the next year's work.
With moderate activity, the five men will lift and lay out 12,000 sods
(3000 cubic feet,) daily, and it is not uncommon that five first-rate
hands get out 16,800 peats (4200 cubic feet,) in this time.
A gang of five men, working as described, suffices for cutting out a bed
of four feet of solid peat. When the excavation is to be made deeper, a
sixth man, the "Hanker," is needful for economical work; and with his
help the cutting may be extended down to nine and a half feet; i. e.
through eight feet of solid peat. The cutting is carried down at first,
four feet as before, but the peats are carried 50 feet further, in order
to leave room for those to be subsequently lifted. The "Hanker" aids
here, with a second wheel-barrow. In taking out the lower peat, the
"Hanker" stands on the bottom of the first excavation, receives the
blocks from the Diggers, on a broad wooden shovel, and hands them up to
the Loader; while the Wheeler, having only the usual distance to carry
them, lays them out in the drying rows without difficulty.
After a little drying in the rows, the peats are gradually built up into
narrow piles, like a brick wall of one and a half bricks thickness.
These piles are usually raised by women. They are made in the spaces
between the rows, and are laid up one course at a time, so that each
block may dry considerably, before it is covered by another. A woman can
lay up 12,000 peats daily--the number lifted by 5 men--and as it
requires about a month of good weather to give each course time (two
days) to dry, she is able to pile for 30 gangs of workmen. If the
weather be very favorable, the peats may be stacked or put into sheds,
in a few days after the piling is finished. Stacking is usually
practised. The stacks are carefully laid up in cylindrical form, and
contain 200 to 500 cubic feet. When the stacks are properly built, the
peat suffers but little from the weather.
According to Schroeder, from whose account (Dingler's Polytechnisches
Journal, Bd. 156, S. 128) the above statements are derived, the peats
excavated under his direction, in drying thoroughly, shrank to about
one-fourth of their original bulk (became 12 inches x 3 inches x 3
inches,) and to one-seventh or one-eighth of their original weight.
c. _Machines for Cutting Peat._
In North Prussia, the Peat Cutting Machine of Brosowsky, see fig. 4, is
extensively employed. It consists of a cutter, made like the four sides
of a box, but with oblique edges, _a_, which by its own weight, and by
means of a crank and rack-work, operated by men, is forced down into the
peat to a depth that may reach 20 feet. It can cut only at the edge of a
ditch or excavation, and when it has penetrated sufficiently, a spade
like blade, _d_, is driven under the cutter by means of levers _c_, and
thus a mass is loosened, having a vertical length of 10 feet or more,
and whose other dimensions are about 24 x 28 inches. This is lifted by
reversing the crank motion, and is then cut up by the spade into blocks
of 14 inches x 6 inches x 5 inches. Each parallelopipedon of peat, cut
to a depth of 10 feet, makes 144 sods, and this number can be cut in
less than 10 minutes. Four hands will cut and lay out to dry, 12,000 to
14,000 peats daily, or 3100 cubic feet. One great advantage of this
machine consists in the circumstance that it can be used to raise peat
from below the surface of water, rendering drainage in many cases
unnecessary. Independently of this, it appears to be highly labor
saving, since 1300 machines were put to use in Mecklenburg and Pomerania
in about 5 years from its introduction. The Mecklenburg moors are now
traversed by canals, cut by this machine, which are used for the
transportation of the peat to market.[18]
[Illustration: Fig. 4.--BROSOWSKY'S PEAT CUTTER.]
Lepreux in Paris, has invented a similar but more complicated machine,
which is said to be very effective in its operation. According to Herve
Mangon, this machine, when worked by two men, raises and cuts 40,000
peats daily, of which seven make one cubic foot, equal to 5600
cubic feet. The saving in expense by using this machine[19] is said to
be 70 _per cent._, when the peat to be raised is under water.
11.--_The Dredging of Peat._
When peat exists, not as a coherent more or less fibrous mass, but as a
paste or mud, saturated with water, it cannot be raised and formed by
the methods above described.
In such cases the peat is dredged from the bottom of the bog by means of
an iron scoop, like a pail with sharp upper edges, which is fastened to
a long handle. The bottom is made of coarse sacking, so that the water
may run off. Sometimes, a stout ring of iron with a bag attached, is
employed in the same way. The fine peat is emptied from the dredge upon
the ground, where it remains, until the water has been absorbed or has
evaporated, so far as to leave the mass somewhat firm and plastic. In
the mean time, a drying bed is prepared by smoothing, and, if needful,
stamping a sufficient space of ground, and enclosing it in boards 14
inches wide, set on edge. Into this bed the partially dried peat is
thrown, and, as it cracks on the surface by drying, it is compressed by
blows with a heavy mallet or flail, or by treading it with flat boards,
attached to the feet, somewhat like snow shoes. By this treatment the
mass is reduced to a continuous sheet of less than one-half its first
thickness, and becomes so firm, that a man's step gives little
impression in it. The boards are now removed, and it is cut into blocks
by means of a very thin, sharp spade. Every other block being lifted out
and placed crosswise upon those remaining, air is admitted to the whole
and the drying goes on rapidly. This kind of peat is usually of
excellent quality. In North Germany it is called "Baggertorf," i. e.
mud-peat.
Peat is sometimes dredged by machinery, as will be noticed hereafter.
12.--_The Moulding of Peat._
When black, earthy or pitchy peat cannot be cut, and is not so saturated
with water as to make a mud; it is, after raking or picking out roots,
etc., often worked into a paste by the hands or feet, with addition of
water, until it can be formed into blocks which, by slow drying, acquire
great firmness. In Ireland this product is termed "hand-peat." In
Germany it is called "Formtorf," _i. e._ moulded peat, or "Backtorf,"
_i. e._ baked peat.
The shaping is sometimes accomplished by plastering the soft mass into
wooden moulds, as in making bricks.
13.--_Preparation of Peat Fuel by Machinery, etc._
Within the last 15 years, numerous inventions have been made with a view
to improving the quality of peat fuel, as well as to expedite its
production. These inventions are directed to the following points, viz.:
1. _Condensation_ of the peat, so as bring more fuel into a given space,
thus making it capable of giving out an intenser heat; at the same time
increasing its hardness and toughness, and rendering it easier and more
economical of transportation. 2. _Drying_ by artificial heat or reducing
the amount of water from 20 or 25 _per cent._ to half that quantity or
less. This exalts the heating power in no inconsiderable degree. 3.
_Charring._ Peat-charcoal is as much better than peat, for use where
intense heat is required, as wood charcoal is better than wood. 4.
_Purifying from useless matters._ Separation of earthy admixtures which
are incombustible and hinder draught.
A.--_Condensation by Pressure._
_Pressing Wet Peat._--The condensation of peat was first attempted by
subjecting the fresh, wet material, to severe pressure. As long ago as
the year 1821, Pernitzsch, in Saxony, prepared peat by this method, and
shortly afterwards Lord Willoughby d'Eresby, in Scotland, and others,
adopted the same principle. Simple pressure will, indeed, bring fresh
peat at once into much smaller bulk; but, if the peat be fibrous and
light, and for this reason require condensation, it is also elastic,
and, when the pressure is relieved, it acquires again much of its
original volume.
Furthermore, although pressure will squeeze out much water from a
saturated well-ripened peat, the complete drying of the pressed blocks
usually requires as much or more time than that of the unpressed
material, on account of the closeness of texture of the surface produced
by the pressure.
The advantages of subjecting fresh peat to pressure in the ordinary
presses, it is found, are more than offset by the expense of the
operation, and it is therefore unnecessary to give the subject further
attention.
Fresh peat appears however to have been advantageously pressed by other
mechanical means. Two methods require notice.
_Mannhardt's Method_, invented about the year 1858, has been practically
applied on the large scale at _Schleissheim_, Bavaria. Mannhardt's
machine consists of two colossal iron rolls, each of 15 feet diameter,
and 6-1/2 feet length, geared into each other so as to revolve
horizontally in opposite directions and with equal velocity. These rolls
are hollow, their circumference consists of stout iron plate perforated
with numerous small holes, and is supported by iron bars which connect
the ends of the roll, having intervals between them of about one inch.
Each roll is covered by an endless band of hair cloth, stretched over
and kept in place by rollers. The rolls are operated by a steam engine
of 12 horse power. The fresh peat is thrown into a hopper, and passing
between the rolls, loses a considerable share of its water, issuing as a
broad continuous sheet, which is divided into blocks by an arrangement
presently to be described. The cloth, covering the rolls, must have
great strength, sufficient porosity to allow water to pass it freely,
and such closeness of texture as to retain the fine particles of peat.
Many trials have led to the use of a fabric, specially made for the
purpose, of goat's hair. The cloth for each pair of rolls, costs $160.
The peat at Schleissheim is about 5 feet in depth, and consists of a
dark-brown mud or paste, free from stones and sticks, and penetrated
only by fine fibers. The peat is thrown up on the edge of a ditch, and
after draining, is moved on a tram-way to the machine. It is there
thrown upon a chain of buckets, which deliver it at the hopper above the
rolls. The rolls revolve once in 7-1/3 minutes and at each revolution
turn out a sheet of peat, which cuts into 528 blocks. Each block has,
when moist, a length of about 12 inches, by 5 inches of width and 1-1/4
inches of thickness, and weighs on the average 1-1/2 lbs. The water that
is pressed out of the peat, falls within the rolls and is conducted
away; it is but slightly turbid from suspended particles. The band of
pressed peat is divided in one direction as it is formed, by narrow
slats which are secured horizontally to the press-cloth, at about 5
inches distance from each other. The further division of the peat is
accomplished by a series of six circular saws, under which the peat is
carried as it is released from the rolls, by a system of endless cords
strung over rollers. These cords run parallel until the peat passes the
saws; thenceforth they radiate, so that the peat-blocks are separated
somewhat from each other. They are carried on until they reach a roll,
over which they are delivered upon drying lattices. The latter move
regularly under the roll; the peats arrange themselves upon them
edgewise, one leaning against the other, so as to admit of free
circulation of air. The lattices are loaded upon cars, and moved on a
tram-way to the drying ground, where they are set up in frames.
The peat-cake separates well from the press-cloths; but the pores of the
latter become somewhat choked by fine particles that penetrate them.
They are therefore washed at each revolution by passing before a pipe
from which issue, against them, a number of jets of water under high
pressure. The blocks, after leaving the machine, are soft, and require 5
or 6 days to become air-dry. When dry they are dense and of good
quality, but not better than the same raw material yields by simple
moulding. The capacity of the rolls, which easily turn out 100,000 peats
in 24 hours, greatly exceeds at present that of the drying arrangements,
and for this reason the works are not, as yet, remunerative. The rolls
are, in reality, a simple forming machine. The pressure they exert on
the peat, is but inconsiderable, owing to its soft pasty character; and
since the pair of rolls costs $8000 and can only be worked 3 to 4
months, this method must be regarded rather as an ingenious and
instructive essay in the art of making peat-fuel, than as a practical
success. The persevering efforts of the inventor may yet overcome all
difficulties and prove the complete efficacy of the method. It is
especially important, that blocks of greater thickness should be
produced, since those now made, pack together too closely in the fire.
_Neustadt Method._--At Neustadt, in Hanover, a loose-textured fibrous
peat was prepared for metallurgical use in 1860, by passing through iron
rolls of ordinary construction. The peat was thereby reduced two-thirds
in bulk, burned more regularly, gave a coherent coal, and withstood
carriage better. The peat was, however, first cut into sods of regular
size, and these were fed into the rollers by boys.
b. _Pressing Air-dried Peat._
Some kinds of peat, when in the air-dry and pulverized state, yield by
great pressure very firm, excellent, and economical fuel.
_Lithuanian Process._--In Lithuania, according to Leo,[20] the following
method is extensively adopted. The bog is drained, the surface moss or
grass-turf and roots are removed, and then the peat is broken up by a
simple spade-plow, in furrows 2 inches wide and 8 or 10 inches deep. The
broken peat is repeatedly traversed with wooden harrows, and is thus
pulverized and dried. When suitably dry, it is carried to a magazine,
where it is rammed into moulds by a simple stamp of two hundred pounds
weight. The broken peat is reduced to two-fifths its first bulk, and the
blocks thus formed are so hard, as to admit of cutting with a saw or ax
without fracture. They require no further drying, are of a deep-brown
color, with lustrous surfaces, and their preparation may go on in winter
with the stock of broken peat, which is accumulated in the favorable
weather of summer. In this manufacture there is no waste of material.
The peat is dry enough for pressing when, after forming in the hands to
a ball, it will not firmly retain this shape, but on being let fall to
the ground, breaks to powder. The entire cost of preparing 1000 peats
for use, or market, was 2 Thalers, or $1.40. Thirty peats, or "stones"
as they are called from their hardness, have the bulk of two cubic feet,
and weigh 160 lbs. The cost of preparing a hundred weight, was
therefore, (in 1859,) four Silver-groschen, or about 10 cents.
The stamp is of simple construction, somewhat like a pile driver, the
mould and face of the ram being made of cast iron. The above process is
not applicable to _fibrous peat_.
c. _Pressing Hot-dried Peat._
The two methods to be next described, are similar to the last mentioned,
save that the peat is _hot-pressed_.
_Gwynne's Method._--In 1853, Gwynne of London, patented machinery and a
method for condensing peat for fuel. His process consisted, first, in
rapidly drying and pulverizing the fresh peat by a centrifugal machine,
or by passing between rollers, and subsequent exposure to heat in
revolving cylinders; and, second, in compressing the dry peat-powder in
a powerful press at a high temperature, about 180 deg. F. By this heat it is
claimed, that the peat is not only thoroughly dried, but is likewise
partially decomposed; _bituminous matters being developed, which cement
the particles to a hard dense mass_. Gwynne's machinery was expensive
and complicated, and although an excellent fuel was produced, the
process appears not to have been carried put on the large scale with
pecuniary success.
A specimen of so-called "Peat coal" in the author's possession, made in
Massachusetts some years ago, under Gwynne's patent, appears to consist
of pulverized peat, prepared as above described; but contains an
admixture of rosin. It must have been an excellent fuel, but could not
at that time compete with coal in this country.
_Exter's Method._[21]
[Illustration: Fig. 5.--EXTER'S DRYING OVEN.]
[Illustration: Fig. 6.--EXTER'S DRYING OVEN.]
In 1856, Exter, of Bavaria, carried into operation on an extensive
scale, a plan of preparing peat-fuel in some respects not unlike the
last mentioned method. Exter's works, belonging to the Bavarian
Government, are on the Haspelmoor, situated between Augsburg and Munich.
According to Ruehlmann, who examined them at the command of the
Hanoverian Government in 1857, the method is as follows:--1. The bog is
laid dry by drains and the surface is cleared of bushes, roots, and
grass-turf, down to good peat. 2. The peat is broken up superficially to
the depth of about one inch, by a gang of three plows, propelled by a
portable steam engine. 3. The peat is further pulverized by a harrow,
drawn by a yoke of oxen. 4. In two or three days after harrowing, the
peat is turned by an implement like our cultivator, this process being
repeated at suitable intervals. 5. The fine and air-dry peat is gathered
together by scrapers, and loaded into wagons; then drawn by rope
connected with the engine, to the press or magazine. 6. If needful, the
peat, thus collected, is further pulverized by passing it through
toothed rollers. 7. The fine peat is now introduced into a complicated
drying oven, see figures 5 and 6. It falls through the opening _T_, and
is moved by means of the spirals along the horizontal floors _O_, _O_,
falling from one to another until it emerges at _Q_. The floors, _O_,
_O_, are made by wide and thin iron chambers, through which passes waste
steam from an engine. The oven is heated further by hot air, which
circulates through the canals _K_, _K_. The peat occupies about one hour
in its passage through the oven and falls from _Q_, into the press,
having a temperature of from 120 deg. to 140 deg.Fahrenheit. The press employed
at Staltach is essentially the same as that now used at the Kolbermoor,
and figured on p. 125. It is a powerful eccentric of simple
construction, and turns out continuously 40 finished peats per minute.
These occupy about one-fourth the space of the peat before pressing, the
cubic foot weighing about 72 lbs. The peats are 7 inches long, 3 inches
wide, and one half to three quarters of an inch thick, each weighing
three quarters of a pound. Three presses furnish annually 180,000 cwt.
of condensed peat, which is used exclusively for firing locomotives. Its
specific gravity is 1.14, and its quality as fuel is excellent.
Ruehlmann estimated its cost, at Haspelmoor in 1857, at 8-1/2 Kreuzers,
or a little more than 6 cents per cwt., and calculated that by adopting
certain obvious improvements, and substituting steam power for the labor
of men and cattle, the cost might be reduced to 6-1/2 Kreuzers, or a
little more than 4 cents per cwt.
Exter's method has been adopted with some modifications at Kolbermoor,
near Munich, in Bavaria, at Miskolz, in Hungary, and also at the
Neustadt Smelting Works, in Hanover. At the latter place, however, it
appears to have been abandoned for the reasons that it could be applied
only to the better kinds of peat; and the expense was there so great,
that the finished article could not compete with other fuel in the
Hanoverian markets.
Details of the mechanical arrangements at present employed on the
Kolbermoor, are as follows: After the bog is drained, and the surface
cleared of dwarf pines, etc., and suitably leveled, the peat is plowed
by steam. This is accomplished in a way which the annexed cut serves to
illustrate. The plot to be plowed, is traversed through the middle by
the railway _x_, _y_. A locomotive _a_, sets in motion an endless
wire-rope, which moves upon large horizontal pulleys _o_, _o_, stationed
at either border of the land. Four gang plows _b_, _b_, are attached to
the rope, and as the latter is set in motion, they break up the strip of
peat they pass over, completely. The locomotive and the pulleys are then
moved back, and the process is repeated until the whole field has been
plowed. The plows are square frames, carrying six to eight shares and as
many coulters.
[Illustration: Fig. 7.]
The press employed at Kolbermoor, is shown in figs. 8 and 9. The hot
peat falls into the hopper, _b_, _c_. The plunger _d_, worked in the
cavity _e_, by an eccentric, allows the latter to fill with peat as it
is withdrawn, and by its advance compresses it into a block. The blocks
_m_, once formed, by their friction in the channel _e_, oppose enough
resistance to the peat to effect its compression. In order to regulate
this resistance according to the varying quality of the peat, the piece
of metal _g_, which hangs on a pivot at _o_, is depressed or raised, by
the screw _i_, so as to contract or enlarge the channel. At each stroke
of the plunger a block is formed, and when the channel _e_ is once
filled, the peats fall continuously from its extremity. Their dimensions
are 7 inches long, 3-1/2 wide, and 1-1/2 thick.
[Illustration: Fig. 8.--EXTER'S PEAT PRESS.]
Several presses are worked by the same engine at the Kolbermoor, each of
which turns out daily 200 to 300 cwt. of peats, which, in 1863, were
sold at 24 Kreuzers (16 cents), per cwt.
[Illustration: Fig. 9.--EXTER'S PEAT PRESS.]
C. Hodgson has patented in Great Britain a compressing-ram similar to
Exter's, and works were put up at Derrylea, in Ireland, some years ago,
in which Exter's process of manufacturing peat fuel appears to have been
adopted.
_Elsberg's Process._
Dr. Louis Elsberg, of New York City, has invented a modification of
Exter's method, which appears to be of great importance. His
experimental machine, which is in operation near Belleville, N. J.,
consists of a cylindrical pug-mill, in which the peat, air-dried as in
Exter's method, is further broken, and at the same time is subjected to
a current of steam admitted through a pipe and jacket surrounding the
cylinder. The steamed peat is then condensed by a pair of presses
similar to that just described, which are fed directly from the mill. In
this way the complicated drying oven of Exter is dispensed with. Elsberg
& Co. are still engaged in perfecting their arrangements. Some samples
of their making are of very excellent quality, having a density of 1.2
to 1.3.
The pressing of air-dry peat only succeeds when it is made warm, and is,
at the same time, moist. In Exter's original process the peat is
considerably dried in the ovens, but on leaving them, is so moist as to
bedew the hand that is immersed in it. It is, in fact, steamed by the
vaporization of its own water. In Elsberg's process, the air-dry peat is
not further desiccated, but is made moist and warm by the admission of
hot steam. The latter method is the more ready and doubtless the more
economical of the two. Whether the former gives a dryer product or not,
the author cannot decide. Elsberg's peat occurs in cylindrical cakes 2
inches broad, and one inch in thickness. The cakes are somewhat cracked
upon the edges, as if by contraction, in drying. When wet, the surface
of the cakes swells up, and exfoliates as far as the water has
penetrated. In the fire, a similar breaking away of the surface takes
place, and when coked, the coal is but moderately coherent.
The reasons why steamed peat admits of solidification by pressure, are
simply that the air, ordinarily adhering to the fibres and particles, is
removed, and the fibres themselves become softened and more plastic, so
that pressure brings them into intimate contact. The idea that the heat
develops bituminous matters, or fuses the resins which exist in peat,
and that these cement the particles, does not harmonize with the fact
that the peat, thus condensed, flakes to pieces by a short immersion in
water.
The great advantage of Exter's and Elsberg's method consists in avoiding
what most of the others require, viz.: the expensive transportation and
handling of fresh peat, which contains 80 to 90 _per cent._ of water,
and the rapid removal of this excess of water before the manufacture. In
the other methods the surplus water must be slowly removed during or
after condensation.
Again, enough peat may be air-dried and stored during summer weather, to
supply a machine with work during the whole year.
Its disadvantages are, that it requires a large outlay of capital and
great expenditure of mechanical force. Its product is, moreover, not
adapted for coking.
B.--_Condensation without Pressure._
The methods of condensing peat, that remain to be described, are based
upon radically different principles from those already noticed. In
these, little or no pressure is employed in the operations; but
advantage is taken of the important fact that when wet or moist peat is
ground, cut or in any way reduced to a pulpy or pasty consistence, with
destruction of the elastic fibres, it will, on drying, shrink together
to a coherent mass, that may acquire a density and toughness much
greater than it is possible to obtain by any amount of mere pressure.
The various processes that remain to notice are essentially reducible to
two types, of which the French method, invented by Challeton, and the
German, invented it appears by Weber, are the original representatives.
The former method is only applicable to earthy, well-decomposed peat,
containing little fibre. The latter was originally applied to fibrous
moss-peat, but has since been adapted to all kinds. Other inventors,
English, German, and American, have modified these methods in their
details, or in the construction of the requisite machinery, rendering
them more perfect in their execution and perhaps more profitable in
their results; but, as regards the essential principles of production,
or the quality of product, no advance appears to have been made beyond
the original inventors.
a. _Condensation of Earthy Peat._
_Challeton's Method_ consists essentially in destroying the fibres, and
reducing the peat by cutting and grinding with water to a pulp; then
slowly removing the liquid, until the peat dries away to a hard coherent
mass. It provides also for the purification of the peat from earthy
matters. It is, in many respects, an imitation of the old Dutch and
Irish mode of making "hand peat" (_Baggertorf_), and is very like the
paper manufacture in its operations. Challeton's Works, situated near
Paris, at Mennecy, near Montanges, were visited in 1856 by a Commission
of the Agricultural Society of Holstein, consisting of Drs. Meyn and
Luetkens, and also by Dr. Ruehlmann, in the interest of the Hanoverian
Government. From their account[22] the following statements are derived.
The peat at Mennecy comes from the decay of grasses, is black, well
decomposed, and occasionally intermingled with shells and sand. The moor
is traversed by canals, which serve for the transport of the excavated
peat in boats. The peat, when brought to the manufactory, is emptied
into a cistern, which, by communicating with the adjacent canal,
maintains a constant level of water. From this cistern the peat is
carried up by a chain of buckets and emptied into a hopper, where it is
caught by toothed cylinders in rapid revolution, and cut or torn to
pieces. Thence it passes into a chamber where the fine parts are
separated from unbroken roots and fibres by revolving brushes, which
force the former through small holes in the walls of the chamber, while
the latter are swept out through a larger passage. The pulverized peat
finally falls into a cistern, in which it is agitated by revolving arms.
A stream of water constantly enters this vessel from beneath, while a
chain of buckets as rapidly carries off the peat pulp. All sand, shells,
and other heavy matters, remain at the bottom of this cistern.
The peat pulp, thus purified, flows through wooden troughs into a series
of basins, in which the peat is formed and dried. These basins are made
upon the ground by putting up a square frame (of boards on edge,) about
one foot deep, and placing at the bottom old matting or a layer of flags
or reeds. Each basin is about a rod square, and 800 of them are
employed. They are filled with the peat pulp to the top. In a few days
the water either filters away into the ground, or evaporates, so that a
soft stratum of peat, about 3 inches in thickness, remains. Before it
begins to crack from drying, it is divided into blocks, by pressing into
it a light trellis-like framework, having thin partitions that serve to
indent the peat in lines corresponding to the intended divisions. On
further drying, the mass separates into blocks at the lines thus
impressed, and in a few days, they are ready to remove and arrange for
further desiccation.
The finished peats from Challeton's works, as well as those made by the
same method near Neuchatel, Switzerland, by the Messrs. Roy, were of
excellent quality, and in the opinion of the Commission from Holstein,
the method is admirably adapted for the purification and concentration
of the heavy kinds of peat.
In Holstein, a French company constructed, and in 1857 worked
successfully a portable machine for preparing peat on this plan, but
were shortly restrained by legal proceedings. Of their later operations
we have no information.
No data are at hand regarding the cost of producing fuel by Challeton's
machinery. It is believed, however, that his own works were
unremunerative, and several manufactories on his pattern, erected in
Germany, have likewise proved unprofitable. The principle is, however, a
good one, though his machinery is only applicable to earthy or pitchy,
and not to very fibrous peat. It has been elsewhere applied with
satisfactory results.