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tion. The oil wells in Canada are in the corniferous beds of 

 the Devonian age. The rocks of the Chemung Period af- 

 ford abundant oil springs in Erie, Seneca and Cattaraugus 

 counties, N. Y. The oil wells of Pennsylvania and Ohio 

 are mostly sunk in Devonian rocks, immediately underlying 

 the carboniferous strata, through which the boring is often 

 carried. The wells near the Little Kanawha river in Vir- 

 ginia, are bored in the same formation. 



When reached by boring it is always found in rocks of a 

 porus nature, in shales or sandstones, and seems to occupy 

 the pores or crevices of the rock. The rock is as it were 

 saturated with it, and the connection between the crevices 

 enable it to permeate considerable distances. When, there- 

 fore, a boring is made in a basin or hollow of this porous 

 rock the pressure of the oil from the surrounding crevices 

 forces it to ascend through the boring, to a level with the 

 source of pressure. In such wells, termed in the oil region 

 pumping wells, no oil can be obtained except by mechanical 

 force. But when, as, is often the case, a gas exists in the 

 crevices of the rock in connection with the oil, the pres- 

 sure of this gas is often sufficient to force the oil to ascend 

 through the borings with great violence. These are termed 

 spouting wells. Indeed at the present time scarcely any other 

 wells are deemed worth working, owing to superior cheap- 

 ness and abundance of the oil obtained from these. In such 

 wells the gas is often found to escape in connection with 

 the oil, and in character and constitution is a hydrocarbon 

 similar to the oil itself. So rich is this gas in illuminating 

 properties that in many places where it escapes from the 

 earth it is used for purposes of illumination. The village 

 of Fredonia, N. Y., is in part lighted by gas collected from 

 a gas well near the village. At the salt works in the Kana- 

 wha Valley a sufficient amount of gas escapes from some 

 of the salt borings to furnish, when burned, heat enough to 

 evaporate the brine. 



The explanation of the existence of this substance in the 



