100 



England, and many parts of the Continent, are supplied. 

 It is evidently composed of two sorts of strata, to external 

 appearance, sufficiently distinct. The one apparently the 

 remains of wood in a charred state, like charcoal or oxide 

 of carbon. This has hitherto escaped the notice of most 

 authors : besides the grain and appearance of wood, com- 

 mon in this and most other coals, it will be known by being 

 the only part in coal that soils the fingers. If separated, 

 it burns like charred wood, leaving a similar residuum*; it is 

 also soft and powdery, like burnt wood ; breaks in a crumbling 

 manner, and falls into small particles f. The other part 

 is more compact, shining, and brittle, easily scratched with 

 a knife. The least touch of the finger hurts its polish. It 

 has a somewhat splintery conchoidal fracture, and seems 

 chiefly carbon mixed with bitumen. It inflames in a moderate 

 heat, yields much smoke, bubbles, and melts something 

 like pitch, and helps the binding or caking, as it is called, 

 (which is the sign of a good coal, at least for housekeeping) 

 and leaves a cinder which lasts a great while, giving a 

 strong heat. The small remains from a common fire are 

 still valuable on that account for the foroe. If burnt lone;' 

 in a violent draught of air, it forms a clinker of no value ; 



* We have reason to believe that it contains no alkali. 



f Mr. Jameson says, " this does not seem a common appearance," when he 

 found " carbonized wood which could not be distinguished from carbonized 

 Fir." v. 2. p. 87. It is probably the smut of Mr. Kirwan. 



