Septonibcr IS, 1868.] 445 [rockham. 



Notes on the origin of Bitumois, together xvith experiments 

 upon the formation of Asphallum ; by S. F. Peckham. Com- 

 municated by Prof. J. D. Whitney, Chief of the Geological 

 Survey of California, fur the Proceedings of the American 

 Philosophical Society. Sej:). 18, 1868. 



The lack of clear definitions of the specific differences existing 

 between the different varieties of bitumen, or perhaps more 

 strictly speaking, the lack of a uniform and exact nomenclature 

 by which to designate those differences, has led to much confu- 

 sion in description, and has rendered a comparison of the notes 

 of different observers a task of much difficulty. It is for the 

 purpose of suggesting a more exact nomenclature, as well as 

 to point out the conformity or nonconformity, of the results of 

 my own observations with existing theories, that the following 

 notes are offered. 



In all the more extended treatises upon chemistry and mine- 

 ralogy, definitions are given in more or less detail of naphtha, 

 petroleum, maltha and asphaltum, as varieties of bitumen. The 

 generic relation of the different forms of bitumen and the dif- 

 ference between asphalt and the allied minerals gua^-aquillite, 

 idrialine, etc.; also the marked differences existing between true 

 solid bitumens and pj-robitumens, or substances yielding bitu- 

 men upon application of heat, has been very clearly pointed out 

 by Dr. T. S. Hunt upon several occasions.* He makes fusibil- 

 ity, and solubility in bi-sulphide of carbon a distinguishing test 

 of all true bitumens, and further shows that substances other- 

 wise resembling bitumens which are not soluble in this men- 

 struum are not coals but derivatives of bitumen. 



It appears to me desirable that the generic term "Bitumen' 

 should be so employed as to include all liquid or solid mineral 

 hj'drocarbons soluble in bi-sulphide of carbon, and minerals from 

 which they may be derived which are not true coals ; coals from 

 which they may be derived being termed bituminous. Regard- 

 ing therefore petroleum as the normal form of bitumen, the 



* Clicm. News, VI. 5, Am. Jcurual of Sci. and Arts, (-2) XXXV. 157. 



