S. F. Peckham—The Origin of Bitumens. 105 
Art. XV.—The Origin of Bitumens; by S. F. PeckHam, A.M.* 
SPECULATION regarding the origin of bitumens has been pur- 
sued during the last half century along several quite different 
lines of investigation, and has been influenced by several differ- 
ent classes of experience. Generally speaking, these lines fall 
into three different classes and embrace those who regard bitu- 
men as a product of chemical action, those who regard it as 
indigenous to the rocks in which it is found, and those who 
regard bitumen as a distillate produced by natural causes. 
The argument for a purely chemical origin of petroleum was 
first brought to the serious attention of scientific men by Ber- 
thelot in 1866. He found that when carbonic acid or the 
earthy carbonates were brought to react with alkali metals at a 
igh temperature, oily fluids were formed similar to or identical 
with those found in petroleam. Byasson produced the same 
fluids by causing steam, carbonic acid and iron to react; and — 
Cloez produced them by the reaction of boiling water upon a 
earbide of manganese. The chemists of this school assume 
that the alkali metals, iron at a white heat and spiegeleisen 
with other raw chemical reagents, exist in the interior of the 
earth, and that petroleum is formed by the reaction upon them 
terrestrial crust. These chemical theories are supported by 
great names, and are based upon very elaborate researches, but 
they require the assumption of operations nowhere witnessed in 
nature or known to technology. 
M. Co d, who has written so fully upon the occurrence 
of bitumen in Albania and Roumania, and C. H. Hitchcock, 
forces act. ‘ 
The opinion that petroleum is indigenous to the rocks in 
which it is found has been maintained with great vigo 
s r by 
T. Sterry Hunt and J. P. Lesley, both of whom have based — 
~ 
* Abstract of Chapter V of the Monograph on Petroleum, prepared for the i 
States. 
Tenth Census of the United 
