154 Mr. Hatch ett'j Obfevv attorn on Bituminous Subfances. 



undoubtedly have been confounded with them, had it not been 

 discovered when paffing from the liquid to the folid flate. 



The elementary principles of bitumen -are, hydrogen, carbon,, 

 fometimes azote, and probably ibme oxygen, which, by its action on 

 the other principles, tends to form the concrete bitumens, and alfo 

 produces that portion of acid obtained by chemical operations. 

 Thefe fame principles, hydrogen and carbon, conftitute the vegetable 

 oils and refms ; and the fame, with fome azote, form the oils and 

 greafe of animals. Now it is known that very fmall changes in 

 the refpeclive proportions of thefe ingredients, and in the circum- 

 ftances which attend the combination of them, will caufe confider- 

 able variations in the nature of the produ&s ; and in like manner, 

 it appears very probable, that when the organized bodies in their 

 recent ftate, and in the full pofTeffion of the above-mentioned prin- 

 ciples, have been buried in a fituation where thefe principles have 

 been long elaborated under certain favourable circumftances, and 

 fubjecl;ed to the action of mineral bodies; I fay that it appears 

 highly probable, that a new combination, which we call bitumen, 

 may be formed, which, although different in fome refpecls from 

 the vegetable and animal products, ftill, however, retains many 

 characters of thofe fubftances from the principles of which it has 

 been formed. 



Hammersmith, 

 April z6 9 1797. 



X. jfn 



