PRELIMINARY REPORT ON PEAT. 
209 
GENERAL DISCUSSION. 
DEFINITION OF PEAT. 
Peat is a substance formed by the slow decomposition of veg¬ 
etable matter in the presence of abundant water. The substance 
of all plants is chiefly made up of three elements, carbon, hydrogen 
and oxygen, and this when immersed in water for an indefinite 
period gradually loses its gaseous constituents, hydrogen and oxy¬ 
gen, until ultimately what is left is mostly carbon. Peat may be 
regarded as an initial stage in the formation of coal; for coal 
is supposed to have once been peat, and to have acquired its rock¬ 
like consistency by being subjected to pressure from overlying sub¬ 
sequently deposited strata, together with heat from the interior of 
the earth, for thousands if not millions of years. 
Peat, being formed only under water or in very wet places, is 
in the natural state completely saturated, sometimes containing ten 
times as much water as solid matter; and it does not part with this 
water very readily. When tnoroughly air-dried, peat contains 
from about 5 to 25% of water (these figures depending partly on 
the physical and chemical properties of the peat itself and partly 
on the climate in which the drying takes place), and even when 
pressed and dried artificially it still contains at least 1 or 2%. 
Peat that has been thoroughly macerated while wet, and not allowed 
to freeze and thaw repeatedly, will, after drying beyond a certain 
rather indefinite point, become comparatively firm and hard, and 
never again absorb enough water to become plastic. The reason 
for this is not well understood, but it is supposed to be due to cer¬ 
tain physical and chemical changes that take place. In this respect 
peat is somewhat analogous to clay, which, as everyone knows, can 
be made plastic again by mixing with water after it has been partly 
dried, but not after burning. 
Besides carbon and water, peat always contains small quantities 
of nitrogen, sulphur, and various other gaseous and volatile sub¬ 
stances which are found in plant juices and tissues, and more or 
less mineral matter, which appears as ash after a sample is burned. 
Some of this mineral matter, has been an integral part of the plants 
themselves, and some has been merely suspended or dissolved in the 
water in which the plants grew, without being taken up by them. 
In very shallow peat deposits the mineral matter may represent 
merely a sort of mechanical admixture of the underlying soil; or in 
dry climates or seasons considerable quantities of it may be brought 
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