a 
52 MABERY—THE COMPOSITION OF PETROLEUM, [April 3, 
different deposits of petroleum were formed 77 situ, or formed in 
other strata and by some natural agency transferred to their present 
location, has not I believe been satisfactorily answered by the 
geologists. In the case of the limestone petroleum, it would seem 
that it must have been formed where it is now to be found, as Hunt 
and Orton have ably maintained. 
The theory of distillation from some other strata is not tenable 
in the light of present knowledge of the constituents of petroleum. 
Neither could any known constituents of plants that could form 
petroleum be distilled, nor could the heavier portions of petroleum 
be distilled ; the result would be only very volatile distillates and 
deposits of coal or graphite. In this condition deposits of petro- 
leum should ‘always be accompanied by coal, or with coal in the 
near vicinity. 
In the case of Pennsylvania and the allied southern Ohio and 
West Virginia petroleum, it would be a great discovery to connect 
these deposits with the coal formations, for then the source would 
unquestionably be vegetable growth and would support the pre- 
vailing opinion that this was the source of petroleum of this class. 
It is reasonable to assume, as is now believed, that Pennsylvania oil 
was not formed in the sandstones, but found its way there by natural 
agencies from lower strata, probably the Devonian shales. The 
infiltration of the crude oil through sandstones would have a purify- 
ing effect. It is quite probable that the very light yellow crude 
oils from the Berea Grit and other sandstones were filtered a second 
time or more into their present positions. 
With reference to the source of the limestone oils, the evidence 
is all in favor of animal origin, and the same is true of California 
oil, although its formation is probably far more recent than that of 
the others. Texas petroleum has not been sufficiently studied in 
relation to its occurrence and composition, but it is evidently of 
more recent origin, like California oil. 
With reference to the second question, is it more reasonable to 
assume, for instance, that the solid paraffine hydrocarbons were 
formed from the lower members of this series, or that the lower 
members were formed from paraffine? On this point some experi- 
mental evidence may be brought to bear. Reichenbach obtained 
paraffine from both vegetable and animal organic matter. Engler 
obtained paraffine by the distillation of fish oil, as Warren and 
Storer had done many years previously. 
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