210 



ranked amongst the most highly elaborated products of the vege- 

 table kingdom. 



Accustomed to witness the production of these substances by the 

 mysterious process of secretion, we find it difficult to conceive 

 their formation by any process, less complex than that which is per- 

 formed by the appropriate energies of an organized body. Hence 

 has arisen much of the difficulty which has occurred, whilst endea- 

 vouring to account for the formation of bitumen, whether solid or 

 fluid. Despairing of ascertaining any particular points respecting 

 its origin, chemists have, until lately, contented themselves with re- 

 garding it as a mineral production, elaborated in the deep recesses 

 of the earth, and of course, in situations which yielded no hope of 

 determining, on what circumstances and principles its formation 

 depended. 



Naphtha, petroleum, and asphaltum, have in general been con- 

 sidered as substances entirely of mineral origin ; and hence the 

 names they have obtained of mineral OIL, mineral TAR, and mineral 

 PITCH. The French chemists have generally adopted the opinion, 

 that naphtha, and even the other fluid bitumens, are the produce of 

 a distillation, effected by subterranean fires, by which the more 

 subtil parts of certain bituminous matters have been raised or sub- 

 limed ; these particles having been condensed into a fluid form, by 

 the coldness of the cavities which exist in rocks, and in which they 

 have become accumulated. 



It undoubtedly may appear, at first view, the more easy and 

 ready way to account for the formation of these matters, by sup- 

 posing them to be the results of certain subterranean operations, 

 performed on substances which are natives of those regions ; than 

 to suppose them to be the results of natural chemical changes, 

 wrought on substances of the vegetable kingdom by operations 

 carried on in the mineral kingdom. But a discovery made within 

 a few years, requires to be particularly noticed here, since it can- 



