lues.] 44Q (Peckluim. 



circumstances as to leave no possibilitj' of a doiiht that it was 

 derived from wood. Tlie observations of Mr. J. P. Lesley are 

 the most conclusive of any that I have met, yet, it appears to 

 me the facts as observed by him, may be accounted for upon an 

 hypothesis more in harmony with tliose connected with the 

 occurrence of mineral oils in other localities.* Several in- 

 stances are cited by Bischof, in illustration of the fact that 

 wood has changed to lignite during the historic period. f The 

 discover}^ of the piles driven in the Thames b}' the ancient 

 Britons, and of timl)er in long abandoned mines, both found in 

 a carbonized condition, will serve as examples. Still more 

 recent discoveries were made at Port Hudson, La., where wood 

 bearing the marks of the axe was found in a sedimentary depos- 

 ite of the Mississippi river in a carbonized or as the writer ex- 

 presses it, bituminized condition. J It is therefore to be inferred 

 that the formation of petroleum from wood}' fibre presupposes a 

 peculiar decomposition, under conditions so extraordinary as not 

 to exist at present ; conditions too that though possible during 

 former geological epochs were then by no means universal, as is 

 proved b}' the fact that petroleum and coal alike occur in almost 

 every formation from the primary to the tertiary, and often in 

 close proximity to each other. The formation in Southern Cali- 

 fornia in which petroleiim and other forms of bitumen occur in 

 vast quantities, contains lignitic remains at rare intervals, prov- 

 ing that the conditions essential to the formation of lignite and 

 petroleum were present at the same time. 



Again, coal is a compound body, while petroleum is a com- 

 pound of compounds — a mixture of many substances of defi- 

 nite constitution. Substances identical Avith those existing in 

 petroleum may be obtained from coal, but it is onlj' upon the 

 decomposition of the coal that they are obtained, while they 

 exist in the petroleum already formed. These substances are 

 also formed b}' the destructive distillation of wood with exclu- 

 sion of oxA'gen, but the}' do not exist in the wood already formed, 

 and are onl}^ f a-med artificially, by processes which are not 

 analogous to any which we have a right to suppose have ever 

 been active in nature. Animal matter may be subjected to such 



* Pro. Am. I'lnl. Soc. X. 33 and 187. t Cliem. and Pliys. Geology, I. 291. 



I Am. Jour. (1) XXXV. 345 — XXXVI. 118. From the description it appears 

 that the remains were lignitic rather than bituminous. 



VOL. X. — oJ 



