14 Elements of Mineralogy. 



then leaves an infoluble refiduum, but ex- 

 prefled oils diflblve it when boiling. It is 

 alfo found in fome rocky parts of Perjia> 

 but feems mixed with petrol, and is there 

 called Schebennaad, Tfienpen, Kodreti.* Mr. 

 Herman, a phyfician of Strqfburgh, mentions 

 a fpring in the neighbourhood of that city, 

 which contains a fubftance of this fort diffufed 

 through it, which feparates on ebullition, 

 and may then be collected, 3 Roz. 346. 



SPECIES VIII. 

 Jet, Gagates, Lapis Obftdianus. 



Jet is much harder than afphaltum, always 

 black, fufceptible of a good polifh and glaffy 

 in its fradure, which is conchoidal ; it is 

 highly eledrical; its fpecific gravity is 1,744; 

 it melts in a moderately ftrong heat with a 

 difagreable fmell, when burnt it leaves a grey 

 earthy ochrous refiduum ; it is infoluble in 

 fpirit of wine. 



It is found in England, Scotland, France, 

 Italy, Germany, &c. 



SPECIES IX. 

 Pitt or Stone Coal. Lithanthrax. 



Coal is a black, folid, compacl, brittle, in- 

 flammable fubftance, of a moderate hardnefs, 



* J^fem. Su(d. 87. 2 Lin. von Gmel. 389. 2 Gcrb. Beytr. 211. 



laminated 



