1 10 Experime7ifs on a Siilstance tvhich possesses 



others, together with the reshi, (allowed to be exclusively a 

 vegetable substance, or at least ouc which only appertains 

 to the organized natural bodies,) there cannot be any doubt 

 that such coals have been formed from wood and other sub- 

 stances belontring to the vegetable kingdom. 



But some mineralogists attempt to draw a line of separa- 

 tion between the coals above mentioned and the others, 

 which theref(/re they call the true mineral coa's. 



This opinion may in some degree be refuted even from 

 the specimens aflorded by the Bovey coal pits, where, as I 

 have observed, a regular gradation mav be seen from wood 

 which is but very imperfectly carbonized, to the substance 

 called stone coal, which in every respect appears to be most 

 nearly if not absolutely similar to the common pit coals*. 



It may however be objected, that such a transition is pe- 

 culiar to this and similar places, and that the pit coal found 

 in other situations where nothing resembling the Bovey coal 

 can be discovered is in reality of a different nature. 



But this objection, I think, may be answered by the re- 

 sults of those experiments on pit coal, Cannel coal, and as- 

 phaltum, which I hare related in the third section of this 

 paper; for, when these were subjected to the action of nitric 

 acic not too long continued, it was found that the acid Hrst 

 dissolved the principal part of the carbonaceous matter, and 

 if then the process was stopped, there remained a substance 

 in a proportion corresponding to that of the bitumen either 

 in pit coal, or principally forming the Cannel coal and as- 

 phaltum, which, although not absolutely in the state of 

 resin, was however in a state intermediate between it and 

 the extractive matter. 



jSloreover I have stated, (hat, under similar circumstances, 

 a substance possessing in a great measure the same proper- 

 ties, mav be obtained bv the known vegetable resins by the 

 action of nitric acid. 



When, therefore, these facts are added to that of the na- 

 tural mixture of resin and asphaltum which is found with 

 the Bovey coal, we to all appearance have almost positive 

 proof that the pit coals are of vegetable origin. 



* Phil. Trans. 1804, p. 308. 



True 



