40 E.B, Andrews on Petroleum in its Geological Relations. 
change from light fluid oil to hard asphaltum. A fine sample 
of bitumen, received from California twelve years ago, interested 
me much as containing many very old bones. This specimen 
prepared my mind to receive statements subsequently made, 
that wild animals were sometimes mired and died in the tarry 
oil springs in that State. 
the origin of petroleum there are different opinions. All 
agree, however, that it must ultimately be traced to vegetable 
or animal substances, the primary combinations of hydrogen 
and carbon being the product of vital force. It is the opinion 
of Dr. J. 5. Newberry and others that petroleum in its present 
form is the product of a slow distillation of bituminous strata. 
From this theory Mr. T. S. Hunt of the Canada Survey, in the 
“Geology of Canada,” p. 526, dissents, and quotes approvingly 
the views of Mr. Wall, who investigated the bitumens of Trini- 
ad, and who writes that the bitumen “has undergone a special 
mineralization, producing a bituminous matter instead of coal 
or lignite. This operation is not attributable to heat, nor of the 
nature of a distillation, but is due to chemical reactions at the 
ordinary temperature and under the normal conditions of cli- 
mate.’ It would appear to be Mr. Hunt’s opinion that the bitu- 
mens, of which petroleum is the liquid form, are the product of 
chemical reactions changing the original organic materials di- 
rectly into oil and kindred hydrocarbons. The facts cited in 
proof are, that oil is found in the cavities of fossils (Orthocerata, 
&c.), and in thin strata composed of certain corals, and in similar 
cases, where the oil must have originated in the places where 
found and directly from the organic materials. I have observed 
many similar facts, particularly in the Devonian limestones of 
Ohio. These facts are conclusive so far as they go. There is 
ormed. 
of this was absorbed by the sediments which now constitute 
often aided by pressure) while in a fluid or semi-fluid state. In 
a special study of the distribution of bitumen in the Paleozoic 
