154 Mr. Hatcuerr’s Odfrvations on Bituminous Subfiances. 
undoubtedly have been confounded with them, had it not been 
difcovered when pafling from the liquid to the folid ftate, 
The elementary principles’ of bitumen are, hydrogen, carbon; 
fometimes azote, and probably fome 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 operationss 
Thefe fame principles, hydrogen and carbon, conftitute the vegetable 
oils and refins; andthe fame, with fome azote, form the oils and 
greafe of animals. Now it is.known that very {mall changes in 
the refpective proportions of thefe ingredients, and in the circums 
tances which attend the combination of them, will caufe confider- 
able variations in the nature of the produéts; and in like manner; 
it appears very probable, that when the organized bodies in their 
recent ftate, and in the full poffeffion of the above-mentioned prin- 
ciples, have been buried in a fituation where thefe principles have © 
been long elaborated under certain favourable circumftances, and 
fubjeted to the aétion 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 refpects froms 
the vegetable and animal produéts, ftill, however, retains. many 
charaéters.of thofe fubftances from the principles of which it has 
been formed. 
HAMMERSMITH, 
April 26, 1797+ 
