HISTORY OF PETROLEUM OR ROCK OIL. 325 



Grand Trunk railway, is about thirteen cents a gallon. The oil ob- 

 tained by Mr. Williams is refined in Hamilton, while that from the 

 northern part of the township has hitherto been sent to Boston, though 

 refining works are now being erected at the wells. The process of 

 refining consists in rectifying by repeated distillations, by which the 

 oil is separated into a heavier part employed for lubricating machinery, 

 and a lighter oil, which, after being purified and deodorized by a pe- 

 culiar treatment with sulphuric acid, is fit for burning in lamps. 



These wells occur along the line of a low broad anticlinal axis which 

 runs nearly east and west through the western peninsula of Canada, 

 and brings to the surface in Enniskillen the shales and limestones of 

 the Hamilton group, which are there covered with a few feet of clay. 

 The oil doubtless rises from the corniferous limestone, which, as we 

 have seen, contains petroleum; this being lighter than the water 

 which permeates at the same time the porous strata, rises to the 

 higher portion of the formation, which is the crest of the anticlinal axis, 

 where the petroleum of a considerable area accumulates and slowly 

 finds its way to the surface through vertical fissures in the overlying 

 Hamilton shales, giving rise to the oil springs of the region. The 

 oil is met with at various depths; in some cases an abundant supply 

 is obtained at forty feet, w'hile near by it is only met wath at three or 

 four times that depth, and sometimes only in small quantities. Every- 

 thing points to the existence of separate fissures communicating with 

 a deep-seated source. At Kelly's wells, however, it would appear 

 that a reservoir has been formed much nearer the surface, where in 

 a bed of gravel and boulders, underlying the superficial clays, the oil 

 rising from the rocks beneath has accumulated. The inflammable gas 

 which issues from the wells is not necessarily connected with the 

 petroleum, inasmuch as it is an almost constant product of the decom- 

 position of organic matters, and is copiously evolved from rocks which 

 are destitute of bitumen. It is similar to the gas of marshes and to 

 the fire damp of coal mines. A curious circumstance is, however, no- 

 ticed by Mr. Robb; the gas which accumulates in the oil pits becomes 

 charged with vapors which produces upon the workmen a sort of 

 intoxication like nitrous oxyd.* This is not surprising when we re- 

 member that volatile hydrocarbons, like amylene, closely related to 

 the hydrocarbons of petroleum, produce similar effects when their 

 vapor is respired. 



The oil wells of the United States are for the most part sunk in the 

 sandstones which form the summit of the Devonian series, but the oils 

 of western Virginia and southern Ohio rise through the coal measures 

 which overlie the Devonian strata, while the wells of Enniskillen are 

 situated much lower, and aie sunk in the Hamilton shales, which im- 

 mediately overlie the corniferous or Devonian limestone. It is not 

 impossible that in Ohio some of the higher strata, such as the sand- 

 stone, were originally impregnated with the bitumen, but in Canada, 



* Mr. Charles Robb, C. E., bas published in the Canadian Journal for July an interesting 

 paper on the oil wells of Enniskillen, to which, as also to a paper by Prof. E. B. Andrews, 

 of Ohio, in Silliman's Journal for July, I am indebted for several facts. 



