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IX. Observations on Bituminous Subjlances, with a Description of the 

 Varieties of the Eh jlic Bitumen. By Charles Hatchett, Efq. F.R.S. 

 Lond. and Edinb. F. L. S. &c. 



Read May 2, June 6, and July 4, 1797. 



§ 1. 



IT is now generally believed that the bituminous fubftances are 

 not of mineral origin, but that they have been formed from 

 certain principles of fubftances belonging to the organized king- 

 doms of Nature, which, after the lofs of animal and vegetable life, 

 have fufFered confiderable changes by long contact and union with 

 mineral bodies. 



Thefe changes have been however fo confiderable, that the 

 bitumens can no longer be referred to their firft origin, and they are 

 therefore regarded by general confent as forming part of the preient 

 mineral fyftem, 



The bituminous fubftances are : 



Naptha, 

 Petroleum, 

 Mineral Tar, 

 Mineral Pitch, 

 Afphaltum, 

 Vol. IV. S Jet, 



