Inflammables 215 



laminated texture, more or lefs fhining, but 

 rarely fufceptible of a good polifh, does not 

 melt when heated, and always leaves fome 

 afhes ; it feems to confift of petrol or afphal- 

 tum intimately mixed with a fmall proportion, 

 of Earth, moftly argillaceous, feldom calca- 

 reous, and often with pyrites ; according to 

 Mr. Gerhard, fpirit of wine extracts a red 

 colour from it, cauftic fixed alkali attacks 

 the bituminous part, and fat oils aft on and 

 form a varnifh, at leaft with fome forts of it : 

 a fixed alkali has never been found in it, nor 

 any fulphur, except it contained pyrites. 

 Four varieties of it deferve to be diftin&ly 

 confidered : none of them are eledrics ferje* 



I. and II. VARIETY. 

 Cannel Coal, and Klllkenny Coal. 



Cannel coal is of a dull black colour, 

 breaks ealily in any direction, and in its 

 fra&ure prefents a fmooth conchoidal furface, 

 if broken tranfverfly : this fort contains moft 

 petrol and in a lefs denfe ftate; hence it 

 burns with a bright lively flame : its fpecific 

 gravity is about 1,27; Klllkenny coal con- 

 tains the largeft proportion of denfe petrol 

 or afphaltum : and hence burns with lefs 

 flame and fmoke, and more (lowly though 

 intenfely, the quantity of Earth in this coal 

 iloes not exceed T ~ of its weight : its. fpecific 

 P 4 gravity 



