257 
likely to promote such chemical changes, in the strata of vegetable 
matter, as would effect its conversion into coal ? This we will 
therefore now inquire into. 
That vegetable substances placed in a mass, in a subterranean 
situation, will, with the aid of moisture, and perhaps, with only that 
which they themselves contain, pass into a peculiar fermentation, 
and become thereby converted into bitumen, has been already 
asserted. Your attention must here, however, be requested to one 
additional consideration; which will serve, very probably, to sup- 
port the application of that hypothesis to the present subject, the 
origin of coal. 
In the promulgation of that hypothesis you perceived, that the 
circumstance, on which the bituminizating process was supposed 
essentially to depend, was the seclusion of the vegetable matter 
from the atmospheric air. According to the accuracy with which 
this part of the process was performed, it necessarily follows, would 
be the approach to a state of perfection, in the product of the ope- 
ration. Now, by a slight revision of what has been said, in the 
Letter immediately preceding this, you will not fail to perceive, 
that whilst endeavouring to ascertain the most probable mode in 
which the vegetable matter of the antediluvian world was disposed, 
there appears great reason to suppose, that the disposition of it 
must have been such, as would most certainly secure the completion 
of the assumed process. 
Buried in a considerable mass,— thoroughly imbued vdth water, 
and covered over with dense, compact strata of earth, its seclusion 
from the atmospheric air must have been very accurate; and 
taking it for granted, that the change it was to undergo would 
depend on these circumstances, then we have every right to con- 
clude, that its conversion into bitumen would be most effectually 
produced. 
VOL. I. 
L L 
