DOMAIN VI. CARBONACEOUS. 



is of general use in the definitions of natural his- 

 tory ; so that there seems no reason for its ex- 

 clusion, while on the contrary its admission af- 

 fords a pleasing variety. 



The account of lignite, given by Brongniart, 

 is so complete, clear, and satisfactory, that it 

 shall be translated with a few subjoined observa- 

 tions ; after premising that one of his varieties, 

 namely jet, rather belongs to lithology in every 

 sense, as it is found in small pieces, and only ap- 

 plied to minute purposes of use or decoration. 



The others are found in large beds or masses, 

 by the Germans called bergarts ; and though 

 many rocks are composed of shells, corals, ma- 

 drepores, and other animal remains, the reader 

 might be startled at the idea of a rock composed 

 of wood. Yet rock-salt, which will be treated 

 among the Anomalous, perhaps affords an idea 

 little less incongruous ; and too great precision 

 would lead to neology, which ought always to 

 be avoided, except in cases of indispensable ne- 

 cessity. Rocks of pumice or of obsidian, or even 

 of topaz, are ideas equally new to the generality 

 of readers, yet they exist in nature, which must 

 be followed, and not controlled. 



" The combustible minerals which belong to 

 this species, are characterised by the odour, and 

 the products of their combustion. The odour 



