108 PECKHAM — THE GENESIS OF BITUMEXS. [April 1, 



THE GENESIS OF BITUMENS, AS RELATED TO CHEMI- 

 CAL GEOLOGY. 



BY S, F. PECKHAM. 



{Read April 1, 1898.) 



1. On the 5th of February, 1897, a symposium was held at the 

 rooms of the American Philosophical Society in Philadelphia, upon 

 '' The Origin and Nature of Petroleum." It was conducted by Profs. 

 S. P. Sadtler and Charles F. Mabery, Dr. D. T. Day, of Washing- 

 ton, D. C, Francis C. Phillips and the writer. While listening to 

 the papers then read, I was impressed with the fact that the dis- 

 cussion proceeded almost wholly without regard to any considera- 

 tion of the different conditions that probably obtained in that 

 primitive world in which the oldest petroleums found their origin. 

 Prof. Mabery discussed, from the standpoint of pure chemistry, 

 the composition of the petroleums of the Trenton limestone ; I, 

 myself, those of the Miocene Tertiary of California ; Dr. Sadtler, 

 the extremely interesting experiments that he had made upon the 

 destructive distillation of the glycerides of linseed oil ; while Dr. 

 Day discoursed upon the somewhat remote and problematic 

 resultant of certain chemical reactions upon bitumen ; and Mr. 

 Phillips presented some exceedingly interesting theoretical con- 

 siderations concerning ''The Genesis of Petroleum and Natural 

 Gas" and "The Occurrence of Petroleum in the Cavities of 

 Fossils." Later reflection has brought very forcibly to my mind 

 considerations that I am led to present as a possible means of 

 reconciling many of the differences that appear in the late discussion 

 of these questions.^ 



2. In view of the general acceptance of the nebular hypothesis, 

 it is unnecessary to establish the fundamental proposition that 

 bitumens, as minerals, are properly considered in their relation to 

 all the other mineral species that have been identified and described 

 as together constituting the earth's crust. The clear distinction of 

 these relations has followed upon many years of research along 

 several lines. It began more than a century ago with the famous 

 discussion waged between the Plutonists and Neptunists, as to 

 whether fire or water had been most active in producing the phe- 



1 Prog. Amer. Phil. Soc, xxxvi, No. 154. 



