64 PROCEEDINGS OF THE AMERICAN ACADEMY. 



Origin of Petroleum. 



In the clear and concise statement of the present condition of the theoretical 

 discussion concerning the formation of petroleum by Professor Edward Orton 

 (Geological Survey of Ohio, 1890), without including the thory of Mendelejcff 

 that highly heated iron or iron carbides within the earth may furnish the 

 world's supply, it is explained that most geologists accept the view that organic 

 matter of vegetable or animal origin constitutes the source, and that it was 

 deposited during the formation of the rock strata. Many insist on substances 

 of vegetable origin as the chief source, and depend upon destructive distilla- 

 tion as an essential agency. A small minority of the geologists, and some 

 chemists, especially the Germans, hold that animal remains may be accepted 

 as the sole source in a process of primary decomposition without distillation. 



The chief difficulty in arriving at any satisfactory conclusion concerning the 

 formation of petroleum depends upon the fact that the principal process is 

 completed, and there remains scarcely a trace of the stages through which the 

 original substances have passed ; or indeed these stages may have been so 

 simple that we have before us in the oil rock all the indications that could ever 

 have been observed concerning the formation of petroleum. Prevailing opinions 

 seem to refer the genesis of the limestone oils to the decomposition of animal 

 remains, and that of other oils to vegetable decomposition. 



The most interesting observation on the natural formation of oil that has 

 come to my knowledge is the experience of Mr. R. A. Townsend, of Petrolia, 

 who has recently returned from India, where during fourteen years he has been 

 engaged by the British governinent in prospecting for minerals and oils. In the 

 oil region of Assam, Beloochistan, and the Punjaub, the surface is bare rock, 

 and the anticlinals are easily located. Approaching an elevation while pros- 

 pecting, he found at the top a bell-shaped depression, into which he descended 

 to a vertical depth of 2,000 feet, and came upon beds of Tertiary oysters from 

 which petroleum was exuding. The excavation had been formed by a thermal 

 spring that had disappeared, leaving the strata bare. No oil was observed 

 above or below the oyster beds. In oil territory owned by Mr. Townsend in 

 Assam, half decayed tree trunks greasy with oil have been excavated. 



One of the serious difiHculties for those who believe in destructive distillation 

 is an adequate source of heat. Organic matter, animal or vegetable, decora- 

 poses readily enough when exposed to the air at ordinary temperatures, but the 

 products are very different from petroleum. 



In the early development of organic chemistry, the nature of the products 

 resulting from the destructive distillation of various forms of organic matter 

 •was recognized. Dippel's oil distilled from bones contains the nitrogen com- 

 pounds pyrrol, pyridine, and their derivatives. Reichenbach (Schweigger's 

 Journal, LXI. 273) identified paraffine as one of the distillation products of ani- 

 mal and vegetable bodies. 



As already mentioned, Warren and Storer established the presence of the 

 hydrocarbons C„H2„ + 2, C„H2«, and C„H2r,-cas distillation products of a lime 

 soap prepared from menhaden oil. More recently Engler has also prepared the 

 petroleum hydrocarbons by the distillation of menhaden oil under pressure. 

 There can therefore be no question as to the ready formation of petroleum from 

 animal bodies when decomposed with the agency of heat. But that the same 



