of some of the Principles of Vegetables into Bitumen , &c. 409 
but in countries which either actually are or were volcanic, we 
should be almost compelled to believe, with the Swedish Pro- 
fessor, that the operations of subterraneous fires have been 
concerned in the formation of these bodies, or rather in the 
conversion of them into their present state. 
But similar substances are found in countries where not the 
smallest vestige of volcanic effects can be discovered, and 
Devonshire most undoubtedly is such; yet, nevertheless, the 
Bovey coal is there found similar to the surturbrand, in most of 
the external, and (from experiments which I made some years 
ago, I believe I may say) chemical properties; to which must 
be added, that both these substances perfectly resemble each 
other, by forming regular strata 
Moreover, the half charred appearance of Bovey coal, and of 
surturbrand, cannot be adduced as any proof, that the original 
vegetable bodies have been exposed to the partial effects of 
subterraneous fire ; for, at this time, we know that the oxidize- 
ment of substances is performed, at least as frequently, and as 
effectually, by the humid as by the dry way. It would therefore 
be superfluous here, to enter into an elaborate discussion, to 
prove that coal and bitumen, with much greater probability, 
have been formed without the intervention of fire ; and I am 
the less inclined to say more upon this subject, as I have already 
published some considerations on it in a former Paper.-f 
Before I conclude, I must beg leave to observe, that as the 
substance which is found with the Bovey coal is, in every 
respect, so totally different from any of the bitumens hitherto 
* Trans, of the Linnean Society, Vol. IV. p. 138. Von Troil’s Letters, 
p. 42. Opuscula Bergmanni, Tom. III. p.239. 
f Trans, of the Linnean Society, Vol. IV. pp. 141, & c. 
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