MINERAL OIL AND NATURAL GAS 35 



The so-called mineral oil and natural gas, the most modern 

 sources of light, heat and power, are now believed to be 

 directly of organic origin. Several writers, including the 

 famous Russian chemist Mendeleeff, have supposed that oil 

 was formed by the action of water on metallic carbides existing 

 in the heated interior of the earth, a process exactly analogous 

 to the formation of acetylene from calcium carbide, but the 

 balance of opinion now inclines strongly to the view that oil 

 and gas are formed by the natural distillation of organic 

 material entombed ages ago in the rocks. AVhether this 

 material was mainly animal or vegetable is still a matter of 

 dispute. If vegetable, it must have been mainly seaweeds, 

 since oil is usually found in rocks of marine origin and is 

 nearly ahvays associated with salt w^ater. Probably in some 

 instances both Foraminifera and Diatoms played an important 

 part, but most oil is now generally believed to be formed from 

 the soft parts of marine animals. Many large fossil Brachio- 

 pods found in the Carboniferous Limestone in Derbj^shire and 

 Yorkshire contain lumps of bitumen exactly like the residue 

 left on distillation of oil, i.e. asphalt. The essential feature of 

 oil formation is evidently anaerobic (without oxj^gen) de- 

 composition of organic matter, the carbon and hydrogen 

 uniting to form hydrocarbons, with elimination of oxygen 

 and nitrogen; whether bacteria played any part in the process 

 is still an open question. At the present time large quantities 

 of oil are obtained in Scotland by distillation of shales rich in 

 organic matter, especially carbon, probably including material 

 of both animal and vegetable origin, as in modern estuarine 

 and marine muds. A product almost exactly like natural oil 

 can also be obtained by distillation of coal, which is certainly 

 mainly vegetable, but this is a costly and unpractical procedure. 



With the exception of a small amount of energy which we 

 can obtain from the tides, the rivers and the waterfalls, or 

 by the pressure of the wind on windmills, the whole energy 

 which man uses in his manifold operations depends on coal 

 or oil or mineral gas. Without these resources of energy man 

 would soon become as "the beasts that perish," and it is all 

 due to chlorophyll, surely one of the most wonderful sub- 

 stances in the whole creation. 



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