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ranked amongst the most highly elaborated products of the vegetable 
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 sublimed ; 
these particles having been condensed into a fluid form, by the cold- 
ness 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 cannot 
