635 



LIGNITE. 



IN giving a place to peat in this arrangement, 

 it seemed also indispensibly necessary to intro- 

 duce those analogous matters, very conveniently 

 designated by Brongniart's term lignite, which 

 are even more intimately connected with coal by 

 tlieir origin and position. 



The superior antiquity of lignite to peat, is 

 proved by its position under considerable depths 

 of alluvial matter, and by the greater degree in 

 which it has undergone the process of bitumi- 

 nization. They differ also in another essential 

 circumstance, namely, that the production of 

 lignite has long since ceased, whereas that of peat 

 is in daily and visible progress. 



In its chemical properties, lignite holds a 

 station intermediate between peat and coal ; 

 while, among the varieties also, a gradation in 

 this respect may be traced ; the brown and more 



