Mr. HatchettV Obfirvations on Bituminous Sub/lanccs. \ 3 1 



ties of the elaftic bitumen, which I {hall foon defcribc, will be 

 fufficient for the purpofe*. 



NAPTHA. 



Naptha is a fubftance well known to Mineralogies as a light, 

 thin, often colourlefs oil, highly odoriferous and inflammable, 

 which is fometimes found on the furface of the waters of fprings, 

 and at other times ifluing. from certain ftrata. 



When expofed to the air, it becomes at firft yellow, afterwards 

 brown, and in the like proportion it thickens, and paftes into 



PETROL or PETROLEUM. 



This has a greafy feel, is thicker than the preceding fubftance, 

 is tranfparent or femitranfparent, and of a reddifh or blackifh brown 

 colour. By air it becomes like tar, and then is called 



MOUNTAIN or MINERAL TAR, Bitumen Petroleum 



TARDE FLUENS. 



This fubftance is vifcid, and of a reddifti or blackifh brown or 

 black. When burned, it emits a difagrceable bituminous fmell, and 

 by expofure to the air it pafles into 



* Bergman was of opinion, that the liquid bitumens were often, if not always, formed 

 From thofe which are folid, by the means of fubterraneous heat ; and exprefies himfclf thus ; 

 " Cxterum ad fidem pronum eft, naptham, petroleum, bituminofofque liquores, quibus 

 abundat Afia, plures harum materierum exhibens non tantum fcaturigines, fed rivulo6 

 quoque, quibus etiam, parcius licet diftributis, Auftralis Europa non caret ; probabile, 

 inquam, eft, has pinguedines liquidas variis antea terris inluefille exficcatas, et mediante 

 colore fubterraneo, fi non femper, fepe tamen fluiditatem recuperalle. Novimus iguem 

 in alto haud raro agere, quamvis in fuperficie vix obfeura ejufdem indicia inveftigare 

 liceat: novimus prseterea e ficco aluminari fchifto petroleum extorqueri jufto calom 

 graduj cui arte exponitur.— Bergman tk Produci'u Vuicaniis OpufcuJaj toin. iii. p. 238. 



S 2 MOUN- 



