250 Notes on Tetr oleum 



bons like amylene, closely related to the hydrocarbons of petro- 

 leum, 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 are sunk in the 

 Hamilton shales, which immediately overlie the Corniferous or 

 Devonian limestone. It is not impossible that in Ohio some of the 

 higher strata, such as the sandstone, were originally impregnated 

 with bitumen, but in Canada from the absence of this substance 

 diflfused through the shales in question, we are forced to assign it 

 to a lower horizon, which is doubtless that of the bituminous De- 

 vonian limestone. This view I have for some time maintained in 

 opposition to those who conceive the bitumen to be derived from 

 the black pyroschists ; see my lecture before the Board of Arts, 

 reported in the Montreal Gazette of March 1, where I asserted 

 that the source of the petroleum was to be sought in the bitu- 

 minous Devonian and Silurian limestones ; besides the Corni- 

 ferous limestone (Devonian,) we have shown that both the Niagara 

 and the Trenton, (of Upper and Lower Silurian age,) contain 

 petroleum. The question of the extent of the supply of pe- 

 troleum is not easily answered ; the oil now being wrought 

 is the accumulated drainings of ages, concentrated along certain 

 lines of elevation, and the experience of other regions has shown 

 that these sources are sooner or later exhausted ; but though the 

 springs of Agrigentum, like those of Derbyshire, have nearly ceased 

 to flow, those of Burmah and Persia still furnish, as they have for 

 ages past, immense quantities of oil ; nothing but experience can 

 tell us the richness of the subterranean reservoirs. It is not probable 

 that the Devonian limestone is equally rich in petroleum through- 

 out its whole distribution, but the exposures of it in the west are 

 too few to enable us as yet to say in what portions the petroleum 

 predominnates ; as however this rock underlies more than one-half 

 of the western peninsula, we may look for petroleum springs much 

 farther east than Enniskillen. A well yielding considerable quan- 

 tities of petroleum is said to occur in the township of Dereham, 

 about a quarter of a mile S. W. of Tilsonburg, and we may 

 reasonably expect to find others along the line of the anticlinal, 

 or of the folds which are subordinate to it. 



