112 



Sabatier showed that it was possible to form a series of hydro- 

 carbons from acetylene by the action of metallic cobalt and nickel, 

 acting as catalytic agents. 



The upholders of the theory of the organic origin of petroleum 

 are divided into two camps according as they favour a vegetable 

 origin or an animal origin. Some suggest that petroleum has 

 been derived in the main by the metamorphism of pre-existing 

 lignite and coal by igneous intrusions or the liberation of heat 

 during long protracted but considerable tectonic disturbances. 

 The first oil-shale actually worked in this country was in close 

 proximity to coal seams, and coal shales as a matter of fact do yield 

 oil and gases on distillation. Coal and peat yield on appropriate 

 treatment considerable supplies of hydrocarbons. The difficulty, 

 however, is that they yield also coke and various oxygenated 

 derivatives of the hydrocarbons which are to seek in petroleum 

 deposits. It is also urged by some that oil shale was the mother 

 substance of petroleum from which this was derived by distilla- 

 tion and that the kerogen of the oil-shale is vegetable in origin, 

 being rich in the tarry and terpene products of plant assimilation. 



The theory with the greatest support holds the original source 

 to be animal in character. The diatoms, corals and other small 

 fry of vast shallow seas are held accountable for much, without 

 reckoning upon the higher types of marine life such as molluscs, 

 fish, and in Jurassic rocks, saurians of various kinds. It is thought 

 that a richly organic mud, a sapropel, accumulated in places on 

 the floor of the sea and was enclosed before decay had gone too 

 far by ordinary silt of sand and mud. During the passage of time 

 the organic matter has, it is thought, suffered progressive chemical 

 change and has been converted into a structureless substance in 

 oil-shales, from which in most cases petroleum, gaseous and 

 liquid, have been distilled by natural heat into overlying sand- 

 stones and limestones, the petroliferous oil-sands and limestones 

 of modern oil fields. Most of the evidence available goes to con- 

 firm the opinion that the English oil deposits, chiefly in "kero- 

 gen " shales, are derived in the first place from marine organisms. 

 There is little evidence favouring a purely inorganic mother sub- 

 stance as the source from which oil has come by chemical inter- 

 action. 



Graphite is a form of elementary carbon and occurs in various 

 degrees of purity in different states. It may be found crystallised 

 in small hexagonal plates, as foliated lumps, thin layers, and 

 compact masses of small or large dimensions. On the 

 whole it is confined to crystalline rocks — to the ancient gneisses, 

 mica schists and granites and to volcanic rocks. Rarely does it 

 occur in sedimentary rocks. It is, however, recorded for some old 

 limestones in Finland and in Ottawa, where in one place is a band 

 of between 20 and 30 feet. It also sometimes occurs in meteorites 

 as cubical crystals. 



The origin of graphite is somewhat of a puzzle. Coal seams 

 traversed by volcanic dykes occasionally show the coal metamor- 



