of some of the Principles of Vegetables into Bitumen , &c. 401 
that, next to the woody fibre, resin is the substance which, in 
vegetables passing to the fossil state, most powerfully resists 
any alteration ; and that, when this is at length effected, it is 
more immediately the substance from which bitumen is pro- 
duced. The instances which have been mentioned corroborate 
this opinion ; for the vegetable extract in one of them, and more 
especially the resin which was discovered in both, must be 
regarded as part of those principles of the original vegetables 
which have remained, after some other portions of the same 
have been modified into bitumen. 
The smallness of the quantity of resin obtained in both the 
preceding cases, by no means invalidates the proof of the above 
opinion ; but, as an additional confirmation of it, I shall now 
give an account of a very singular substance, which is found 
with the Bovey coal. 
§V. 
Dr. Milles, in his remarks on the Bovey coal, (which I have 
several times had occasion to notice in the course of this Paper,) 
states, that “ amongst the clay, but adhering to the coal, are 
“ found lumps of a bright yellow loam, extremely light, and so 
“ saturated with petroleum, that they burn like sealing wax, 
“ emitting a very agreeable and aromatic scent.”* 
This substance, I also observed, when I visited the Bovey 
coal-pits, in 1794 and 1796. At that time, however, it was 
scarce, and I could only procure one small specimen, which is 
now in the British Museum ; but, from a cursory examination of 
it, I was convinced that it was a peculiar bituminous substance, 
and not loam impregnated with petroleum, as Dr. Milles had 
supposed. I could not then conveniently make a regular analysis 
* Phil. Trans. Vol. LI. p. 536. 
3 F a 
