130 Mr, Hatcuett’s Odbfervations on Bituminous Subftances. . 
_ 
Jet, 
Pit Coal, 
Bituminous Wood, . 
Turf, 
Peat, and 
thofe combinations of the oxides of certain metals with bifumer: 
called Bituminous Ores*. 
Thofe who are acquainted with the nature of thefe fubftances 
will immediately perceive, that they may be formed. into two divi- 
fions: the firft of which confifts of fimple fpecies, or unadulterated | 
bitumens: and the fecond is compofed of bitumen mixed or com- 
bined with the earths, vegetable matter, and metallic oxides; fo that: 
thefe appear to merit the name of compound {pecies: 
- I fhall now firft confider how the fimple {pecies are connected 
with each other. 
2 
IT has been the opinion of fome eminent Naturalifts and Chemitts, 
that naptha is an ethereal oil produced from the more compaé 
and folid bitumens by a fort of natural diftillation. This however 
appears to be an hypothefis founded upon analogy, and fupported 
only by.a few local faéts which may often be queftioned. But 
many faéts and obfervations concur to prove that the contrary moft 
frequently happens, and that the compact bitumens are often, if 
not always, formed from naptha and petroleum by infpiffation. 
Iwill not however now infift upon the proofs of this, asthe varie- 
* As I intend only here to notice the modifications of naptha and petroleum, I have 
not mentioned amber and the honey-ftone. 
‘= 
ties. 
