62 (Review of decent Literature. 
Preliminary report upon petroleum and inflammable gas. Bj Edward 
Orton, State geologist of Ohio. (A publication of the Ohio geological 
survey.) This is a valuable compend of the principal facts relating 
to the gas and oil supply of Ohio. In November, 1884, high-presure 
gas was discovered at the depth of about iioofeetat Findlaj, in Han- 
cock covinty. The surface signs of gas had been very well known for 
many years, and some enterprising gentlemen had devised plans for mak- 
ing use of it by collecting it and lighting their residences, but its source 
had not been discovered, nor even conjectured. It was a complete geolo- 
gical surprise to find the Trenton limestone which nowhere rises to the 
surface in Ohio, a source of gas, and later of oil, in large amount and 
great value. The success at Findlay produced a widespread expectation 
that the Trenton limestone was gas-bearing everywhere throughout the 
state, and a great many wells were drilled to it, and into it, without suc- 
cess, the most of them being about 1200 feet deep. This expectation has 
not been verified. But a small proportion of the wells that have been 
drilled have proved productive. Findlay, Bowling Green, and Lima 
respectively in Hancock, Wood and Allen counties in the N. W. part of 
the state were the fortunate points where success had been met with- 
Prof. Orton describes other geological horizons at which gas has been 
found in Ohio, viz. the Ohio shale, the Berea grit, the Clinton, Medina 
Hudson river and Utica shales and the glacial drift, and concludes with 
the statement that natural gas is one of the common and widely distri- 
buted substances in nature, and a little of it at least can be found any- 
where. This brochure is filled with important practical statements of facts 
and principles that bear directly on the origin, consumption, nature and 
discovery of gas in Ohio; and its value to the State, if it be properly dis- 
tributed and heeded, will be more than the entire cost, great as it is, which 
the survey has been to the State from its inception to the present time. 
It is one of the most practical exemplifications of the value of a geologi- 
cal survey in such emergences as the late fever on gas and oil which 
spread over northwestern Ohio. This preliminary report is to be fol- 
lowed by a complete exposition of the whole subject, in the light of later 
developments. 
Some of the general principles stated by Prof. Orton are as follows: 
Petroleum, which is the necessary preliminary to the existence of gas, 
is derived from vegetable, or vegetable and animal substances that were 
deposited in, or associated with, the forming rocks. 
Petroleum is not in any sense a product of destructive distillation, but 
is the result of a peculiar chemical decomposition by which organic mat- 
ter passes at once into this or allied products. It is the result of the 
primary decomposition of organic matter. 
The organic matter still contained in the rocks can be converted into 
gas and oil by destructive distillation, but so far as we know in no other 
way. It is not capable of furnishing any new supply of petroleum under 
normal conditions. 
Petroleum ii in the main contemporaneous with the rocks that con- 
