164 Fossils. 



Mineral Tar is petrol farther altered by 

 the air, having become of the colour and 

 consistency of pitch. 



Asphaltum, or mineral pitch ^ is produ- 

 ced by a still farther exsiccation or 

 drying. 



Jet is a substance of a full black, hard- 

 er, and less brittle than asphalt ; and ac- 

 cording to Wtdcnrnan, is a species of 

 coal. 



Cannell'Coal appears to be next to jet, 

 in gradation, of the compound mineral 

 bituminous substances. 



Mineral Tallow is rarely met with, and 

 imperfectly known. It much resembles 

 tallow. 



Mineral Caoutchouc is a substance 

 much resembling, in its elastic properties, 

 the substance from which it takes its 

 name. 



Pit-coal, according to Mons. Gensannc 

 and others, is an earth or stone, chiefly of 

 the argillaceous genus, penetrated or im- 

 pregnated with petrol or asphalt. It has 

 also been supposed to hav 7 e been formed 

 by vegetables growing in the sea, and by 

 vast forests which have been buried br 

 subsequent revolutions, 



