^8 PETROLEUM AND NATURAL GAS. [Feb. 5, 



petroleum have been Hofer and Engler. The former of these 

 writers in his work, Das Erdoel und seine Verwandten, published 

 in 1888, summarizes the arguments for believing petroleum to be of 

 animal origin as follows : 



1. We find petroleum in original deposits with animal remains, 

 but not or with only the smallest traces of vegetable remains, as for 

 -example in the fish shales of Carpathia and the limestones of Can- 

 ada studied by T. Sterry Hunt. 



2. Shales which, on account of their high per cent, of bitumen, 

 are adapted for the production of oil or paraffine, are also rich in 

 animal and poor or entirely void of vegetable remains, as for 

 example the bituminous shales of the Lias formation in Swabia and 

 Steierdorf (Banat). The copper-bearing shales of Mansfield, which 

 contain as high as twenty-two per cent, of bituminous matter, also 

 carry an abundance of animal remains, but only very rarely any 

 vegetable remains. 



3. Rocks which are rich in vegetable remains as a rule are not 

 bituminous, but they become so if animal remains accompany the 

 other. 



4. By the decomposition of animal remains it is possible to form 

 hydrocarbons analogous to those of petroleum oils. 



5. O. Fraas observed petroleum oozing from a coral bank on the 

 borders of the Red Sea, where it could only have had an animal 

 origin. 



The fact that origin from animal remains makes it necessary to 

 account for the nitrogen, is met by the fact that most asphalts and 

 bitumens, including petroleum, do contain nitrogen. That they do 

 not contain more is explained, according to Hofer, by the circum- 

 stance that the nitrogen is lost in volatile compounds like ammonia. 

 Of course animal remains are found in many formations that do not 

 contain bitumen or petroleum, but the conditions may have been 

 unfavorable for its accumulation and retention in these cases. The 

 actual formation of petroleum-like compounds from animal pro- 

 ducts had been carried out experimentally some years before 

 Hofer' s publication, by our countrymen, Warren and Storer, who 

 distilled the lime soap of menhaden (fish) oil, and obtained mem- 

 bers of the methane, ethylene and benzene series of hydrocarbons, 

 such as are found in petroleum. 



However, Hofer' s theory was taken up as the suggestion for 

 experimental study by Engler, of Carlsruhe, and at his hands it 



