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carbons and unsaturated compounds, such as are found in the 

 petroleum of Galicia and other districts. Sabatier does not 

 pretend that other theories of the formation of these natural 

 hydrocarbons are necessarily excluded, but he claims that no 

 other theory serves to account for the diversity observed in the 

 composition of petroleum from different regions, and especially 

 for the production of the naphthenes. 



On the other hand, the suggestion is offered that large masses 

 of vegetable or animal matter may have accumulated in past 

 geological times, that they may have undergone decay, and that 

 subsequently a process corresponding to that which has given 

 rise to coal gradually set in. Later a rise of temperature sufficient 

 to cause complete chemical decomposition must be assumed, 

 and this would cause the oil, and gas which would be formed at 

 the same time, to pass from lower to higher strata, and still be 

 retained under the pressure of superincumbent rock. 



Such a view is consistent with the fact that oils closely similar 

 to natural oil are obtained by the action of heat on coal and 

 shales as in the manufacture of paraffin oil from these materials. 



It also would explain the existence of petroleum in so many 

 cases in strata in which no animal or vegetable remains are 

 found, and in fact the general distribution of petroleum in the 

 crust of the earth without apparent connection with the geo- 

 logical age or character of the rocks in which it is found. 



That petroleum may have originated in beds of animal or 

 vegetable matter is rendered probable by the fact that certain 

 varieties have the power of rotating a ray of polarised light, 

 while nearly all contain an appreciable quantity of nitrogen in 

 the form of nitrogenous bases similar to those which are derived 

 from the distillation of coal or animal matter. A small quantity 

 of sulphur in the form of an organic sulphide is also frequently 

 present. 



It is quite possible, in view of the variation in the composition 

 and character of the oil found in different regions, that petroleum 

 may have been produced from both mineral and organic 

 sources. 



There is, however, something fascinating in the idea that this 

 valuable natural product may be actually in process of formation 

 now and always from the body of the earth itself without the 

 intervention of living beings. 



There are, however, outstanding difficulties in respect to all 



