64 Oi-iginal Articles. [Jan., 



Petroleum, It contains much carbonaceous matter, and is supposed 

 by him to be sufficient for generating the supplies forced to the 

 surface by the conjoined pressure of water and carburetted hydrogen, 

 furnished from the same material. It is from these states that the oil 

 springs of Canada West issue, and these are far distant from the coal 

 formation. 



The origin of these hydrocarbon compounds is, however, still a 

 vexed question. That they are the product of the fermentation of 

 either vegetable or animal substances, is admitted on all hands. In 

 the United States there is no evidence to contradict the supposition 

 that they result from the bituminous fermentation of vegetable matter ; 

 but in Canada, where they are found in the lower Silurian limestone, 

 they have been suspected to be of animal origin. " The cavities of 

 large orthoceratites have been found filled with Petroleum, but so fetid 

 as to be most offensive." As to the duration of the suj)ply, there is, 

 of course, no certainty. The Eainanghong wells in Burmah have 

 flowed for ages ; and some of these American wells have resisted the 

 steam pump successfully for four years. If Petroleum is regarded as 

 having passed through the intermediate stage of an association with 

 bituminous shale or coal, and having undergone a process of distilla- 

 tion, the observations of Professor H. D. Rogers as to the greater and 

 greater decrease of volatile matters in the Appalachian coal field, as 

 you come from the west toward the east, would be of great importance. 

 He states that at the western limit, where the strata are still horizontal, 

 the proportion of volatile matter may reach forty or fifty per cent., 

 while on the eastern side, in the boldest flexures of the Appalachian 

 chain, where the strata have been actually turned over, we find the 

 coal to contain only from six to twelve per cent, of bitumen, thus be- 

 coming a genuine anthracite. Sir Charles Lyell, in examining these 

 observations says, that " there is an intimate connection between the 

 extent to which the coal has parted with its gaseous contents, and the 

 amount of disturbance which the strata have undergone. The coin- 

 cidence of these phenomena may be attributed partly to the greater 

 facility afforded for the escape of volatile matter, where the fracturing 

 of the rocks had produced an infinite number of cracks and crevices, 

 and also to the heat of the gases and water penetrating these cracks 

 when the great movements took place which have rent and folded the 

 Appalachian strata. 



Professor E. W. Evans, of Marietta College, has recently pub- 

 lished the result of his investigations on oil wells in the 'American 

 Journal of Science.' He thinks that the principal supplies of 

 Petroleum are not diffused between the planes of stratification, but 

 are collected in cavities more or less sunken in the strata, where it is 

 less liable to be carried away by running water. The places in which 

 it is sought for with most prospect of success are those where there 

 are marks of disturbance and displacement of the rocks. The cavities 

 have been caused by erosion or uplifts, and are usually of slight, hori- 

 zontal extent, so that two neighbouring wells but rarely strike oil at 

 the same depth. Besides, the drill, as it enters the oil cavity, sinks, 

 variously, from four or five inches to as many feet, sometimes sticking 



