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NEW YORK STATE MUSEUM 



a large development in Northeast, Pa. during the last 20 years. 

 Wells have been drilled here by the score and in still larger num- 

 bers at Erie, a few miles farther west. Within the city limits 

 of Erie the gas of the underlying rocks has been reduced to 

 incipient exhaustion by the number and close proximity of the 

 wells put down. 



In Ohio, tests have been made in every county of the lake 

 shore belt. In the thriving villages along the line many wells 

 have been drilled and the gas has been utilized in each to the 

 value of thousands of dollars, annually, as counted by the fuel 

 it displaces. 



Origin of the gas. 



That the gas of the shale belt is derived from petroleum stored 

 in the same rock series seems highly probable. There is no diffi- 

 culty as to the storage of the petroleum. The clays which con- 

 stitute a iarge percentage of the shales have a natural affinity 

 for mineral oils, absorbing and retaining them indefinitely. That 

 petroleum is present in the series is proved not so much by the 

 pockets of it containing a few gallons or a few barrels, as the 

 case may be, that are occasionally reached in the process of 

 drilling, as by its universal diffusion through the substance of 

 the shales. In many instances every fragment of the shale, blue 

 or black, brought up from a well, discloses the presence of petro- 

 leum to 'the senses of both smell and taste. The percentage is 

 small, but the total amount of petroleum is considerable. A 

 few years since an examination was made of drillings taken from 

 1000 feet below the surface at North Kingsville, Ashtabula co. 

 O. The petroleum was extracted by treating the shale fragments 

 with bisulphid of carbon, after they had been reduced to as fine a 

 state of division as possible in an agate mortar. The result 

 was the demonstration of the presence of at least one tenth of 

 Vf> of petroleum, as such, in the shales. Now if the series of 1000 

 feet is fairly represented by this determination, what amount of 

 petroleum does it contain? The figures stand for a layer of 

 petroleum one foot thick. This would amount to more than 

 328,000 gallons to the acre. 



That petroleum gives rise to gas is a matter of common obser- 

 vation, and therefore the only question with which we are con- 



