205 
sufficient to reduce it to a fluid bitumen. That a portion of it has 
undergone even this change, may justly be inferred, from the actual 
presence of bitumen in different parts of the mass ; as well as from 
the bituminous impregnation of the roof, which impregnation was 
most likely to have proceeded from the absorption of the fluid bi- 
tumen, much of which, from its levity, would rise to the upper part 
of the closely pressed mass of bituminous wood. The flat shivery 
state of that which is termed the knotty coal, as well as of that which 
is termed the hoard coal, seems to point out, that, after the bitumi- 
nization had proceeded to a certain point, this substance had been 
deprived of its moisture; the state in which it is found being 
exactly that, in which wood, having suffered such a degree of bitu- 
minization, might be expected to be found, after having been per- 
mitted to become dry. Nor is it an objection of any force that i 
is now found in a moist state ; since, supposing its exsiccation to 
have been once complete, and the fermentative operation quite 
stopped, no subsequent addition of moisture could be expected to 
renew the fermentation, or to soften it so as to render it capable of 
uniting in a close mass. 
Yours, &c. 
