■ Related Geological Conditions 57 



may have been merely due to the fact that the coal Is the 

 last rock through which the oil passed to the surface." 



The writer also, when making field studies of the oil- 

 shales of Midlothian in Scotland, was often impressed by 

 the presence of flattened impressions of the stems and 

 branches of Lepidodeiidron, Lepidophloios and JJloden- 

 droH, side-by-side with those of various species of Calci- 

 ferous Sandstone fishes, the shale itself being completely 

 permeated by the bituminous products, that at once began to 

 "sweat out" when a piece of the shale was heated. Red- 

 wood gives a valuable and condensed epitome of the argu- 

 ments for a vegetable and animal origin of the petroleum 

 on pp. 272-283 of his first volume, and to it the reader is 

 referred who desires added information. 



If it be now asked: What became of the oil, fatty 

 tissue, or muscles of ancient fishes when these were en- 

 tombed wholesale, the first suggestive answer was given 

 In 1867 by the exact chemical investigations of Warren 

 and Storer (57:121-176). Experimenting with menhaden 

 oil they converted this into a soap, by blowing steam into 

 a mixture of lime and the oil. The soap was then strongly 

 heated, and the distillate obtained was a crude petroleum 

 oil. By redistillation many of the characteristic hydro- 

 carbons that are now manufactured from petroleum oil 

 were obtained, such as amylene, caproylene, benzole, tol- 

 uol, xylol, isocumole, etc. But a matter of considerable 

 interest, in relation to the pitch or bituminous strata of 

 Seefeld, Caithness, and many other places mentioned in 

 later pages, was "the separation of a sort of tar" (p. 185) 

 from one of the liquors obtained during the investigation. 



It was stated above that a mixture of lime with the 

 fish oil was treated with steam. Now in the great ma- 

 jority of cases, bituminous fish beds contain a moderate 

 to large amount of calcareous material; while volcanic 

 action seems unquestionably to be associated with the for- 

 mation of such beds. This again would suggest a possible 

 superheating of the strata and their enclosed organisms, 

 some time subsequent to their deposition. Still later, earth 

 movements and upliftings or foldings, to produce that usual 

 anticlinal relation of rocks which so often Is characteristic 



