408 Mr. Hatchett's Observations on the Change 
Bitumen, therefore, with the exuviae and impressions so 
commonly found in the accompanying strata, must be more 
immediately regarded as the proofs, in favour of the origin of 
pit coal from organized bodies; and, considering the general 
facts which have been long observed, together with those lately 
adduced respecting the Bovey coal, and the substance which is 
found with it, we seem now to have almost unquestionable 
evidence, that bitumen has essentially been produced by the 
modification of some of the proximate principles of vegetables, 
and especially resin. 
Modern chemistry had comparatively made but a small pro- 
gress, when the illustrious Bergmann published his Dissertation 
entitled Producta Ignis subterranei chemice considerata; for, at 
that time, the extent and power of chemical action, in the humid 
way, were very imperfectly understood. In that part, however, 
of the above work, where he speaks of the fossil wood of Iceland, 
called Surturbrand, he evidently appears doubtful how far vol- 
canic fire may have acted upon it ; although he conceives that, 
in the formation of it, there has been some connection with 
volcanic operations. His words are, “ Quid de ligno fossili 
“ Islandiae sentiendum sit, gnaro in loco natali contemplatori 
“ decidendum relinquimus. Interea, ut cum vulcani operationibus 
“ nqxum credamus, plures suadent rationes, quamvis hucusque 
“ modum ignoremus, quo situm texturamque adquisiverunt 
“ hsec strata." It certainly was very natural that Bergmann 
should entertain this opinion, in respect to the surturbrand; 
and it is remarkable, that the leaves contained in the schistus 
lately described, are of the same nature, and are found in the 
same country. The leaves also described by Mr. St. Fond, 
are likewise found in a country which, according to him, was 
formerly volcanic. Were these substances, therefore, never found 
