61 



the seav crawling out to bask on the shores. Fish reptiles, the 

 Ichthyosaurians, occurred in vast abundance in the waters of the 

 -sea, there competing not only with the Plesiosaurians, but also 

 with turtles and croeodilians. Gigantic land reptiles such as the 

 Dinosaurians roamed the earth and found plenty of food in the 

 great cycadean forests of the period, while above land and sea 

 flying reptiles, the Pterodactyls, displayed some measure of 

 mastery over the air. Most of the material of the carcasses of this 

 vast concourse of life was doubtless again resolved into its 

 elements by the ordinary agencies of decay, but it is surely not 

 beyond chance that some at least became locked up within the 

 mass of inorganic mud before the processes of decay had run their 

 full course. Possibly locally within the depths of the central sea 

 or at intervals in the course of a long period of time, conditions 

 favoured the preservation of organic waste, preventing its decay, 

 much as the decay of vegetable matter is soon arrested in the 

 formation of peat, and enclosing it in an inorganic matrix. 



The "coal" itself contains Upper Kimmeridgian fossils, and 

 some, as species of oysters, were evidently the denizens of fairly 

 shallow waters, while others similarly pelagic or littoral occur in 

 the shale immediately below. The forms thus intimately associ- 

 ated with the coal cannot, however, be regarded as contributing, 

 except in the slightest possible degree, to the bituminous material 

 of the coal. The principal source of the oil was most probably the 

 prolific and exuberant animal life of the higher types, chiefly the 

 reptiles and fishes, though vegetable waste, marine and land, and 

 •derived coal mud, may also have added their quota. 



The Chemistry and Theories of Origin of Oils. 



By A. Teichfeld. 



The Chemistry of Mineral Oils, comprising free petroleum 

 oils and oils distilled from shale, has been considerably extended 

 of recent years by research, both academic, as a result 'of theo- 

 retical speculations on the origin of the oil, and technological, 

 under the necessity, in some cases, of removing deleterious 

 impurities, chiefly sulphur. 



Various theories on the origin of petroleum have been urged 

 from time to time. Before discussing the most typical of these it 

 appears well to premise some short description of the various 

 groups of hydrocarbons composing petroleum. The chief are 

 these : — 



I. The Paraffins, or straight open-chain saturated hydro- 

 carbons. 



II. The Iso-Paraffins, or side chain saturated hydrocarbons 

 isomeric with the first. 



