Dr MacCulloch on Peat. 
213 
matter in close vessels, under a species of pressure which waa 
supposed to possess a power of modifying the results to this 
end. But the produce in this case is neither coal nor even as- 
phaltum, nor is it in the slightest degree bituminized. It is, in 
fact, the pitch or bistre, produced in the ordinary process of the 
destructive distillation of wood ; nor could even that solid sub- 
stance be obtained, unless by some careless mode of conducting 
the experiment, so as to suffer the more volatile products to 
escape. It is also certain, that the effect which fire does not 
produce in the commencement of its action on vegetable mat- 
ter, it does not produce at any stage ; and that in no case is it 
capable, in our hands at' least, of effecting the change from 
those substances into bitumen. 
Thus far alone does it at present appear in our power to il- 
lustrate the nature of peat, and of the bituminated lignites with 
which it is so nearly allied. But it would be wrong to con- 
clude this subject without entering, however slightly, on a much 
more conjectural field of inquiry, namely, the possible relation 
of peat to coal. This is a geological question of great impor- 
tance, but on which, unfortunately, there is not much real in- 
formation or solid reasoning to offer. 
In examining the mechanical disposition of peat-mosses and 
of coal, a considerable resemblance presents itself. The for- 
mer occur in strata more or less extensive, as the latter do ; and 
in both, the strata vary in thickness in different parts, common- 
ly disappearing in a thin edge. Strata of peat are also occa- 
sionally found, like coal strata, repeated above each other in the 
same place, and separated by beds of sand, clay, and marl ; 
substances corresponding, in every respect but induration, to the 
sandstone, shale, and limestone of coal-fields. In both also, 
there are occasionally found remains of animals and vegetables, 
of which the organization is not destroyed ; and this is most re- 
markable in the peat of estuaries, where these have been entang- 
led in the earthy matters as they are in the shale of coal-fields. 
Where peat has been formed in lakes or extensive marshy cavi- 
ties, it occupies distinct spots, separated from others of the same 
nature, as are those deposits of coal which have been called In- 
dependent Formations. 
