23 ; 
and fitted, for being deposited in strata of coal ; and that the coals, 
with their concomitant strata, were among the last that were formed. 
But how, and by what means, every thing in this great work was 
fitted, and carried on, belongs to higher wisdom and intelligence 
than mine to explain*.” 
“ I will beg leave,” Mr. Williams saysf, “ to propose another 
probable source of coal. I believe I may call it a real one ; and that 
is the antediluvian peat -bog.” The grounds on which Mr. Williams 
formed this opinion were, the having seen coals, which seemed to 
bear a very strong resemblance to peat ; and, on the other hand, 
peat, which, on being dried, became nearly as black, and as hard, 
as coal. The particular reasons Mr. Williams employs for this latter 
opinion, I shall at present defer, since they will appear when I shall 
presume to offer some conjectures on this subject. Petroleum, Mr. 
Williams is, however, convinced, is not at all concerned in e 
formation of coal ; although he acknowledges that some species o 
petroleum may have a near relation to coal. 
It is right to apprize you, that not only has the conversion of 
petroleum into coal been thus strenuously opposed,^ but that the 
derivation of petroleum itself from vegetable matter is also denied. 
The learned Wallerius strongly objects against such an origin; 
grounding his objections chiefly on it differing so much in its sen- 
sible, as well as chemical qualities, from vegetable matter. He is 
the more confirmed in his opinion, from the petroleum being found 
inclosed in mountains, and in subterranean cavities, where no traces 
of decayed vegetables are to be seen. Considering also, that 
there is no reason to suppose that nature is less disposed to form 
an oil in the mineral kingdom, than in any of the othep, he cm 
eludes that naphtha is generated from a most subtile inflammable 
* History of the Mineral Kingdom, vol. ii. p. 212, f Id. vol. ii. p- I®!*- 
i 
