1819.] . the different Species of Pit-Coal 85 



very well characterized. It does not occur in any of the six 

 Glasgow beds of coal. What is burned in that city comes 

 chiefly from Lismahago, and occurs in beds situated above all 

 the Glasgow beds. It is found also in different parts of Airshire, 

 where it is manufactured into ink-horns, snuff-boxes, and other 

 similar trinkets. It abounds, as is well known, at Wigan, in 

 Lancashire. There is a mine of it in Lord Anglesea's park at 

 Beaudesert, not far from Coventry, which his lordship keeps for 

 his own private consumption. 



Colour dark greyish-black; sometimes brownish-black. 



Lustre glistening ; resinous. It takes a good polish. 



Fracture usually large and flat conchoidal. In the great, it is 

 frequently slaty. 



In some varieties, the fragments approach the cubic shape ; 

 in others, they are wedge-shaped, or even quite irregular. 



About the same degree of hardness as the other species of 

 coal. 



Brittle. Does not soil the fingers. 



Much more difficultly frangible than caking coal or cherry 

 coal ; but more easily broken than splint coal. 



Specific gravity 1*272. 



When applied to the flame of a candle, it catches fire, and 

 burns with a strong yellow flame without melting. This easy 

 combustibility induces many persons to employ cannel coal to 

 light their rooms as a substitute for candles. For this purpose, 

 they put apiece of it on the top of their fire, and supply its place 

 with another piece, as soon as it is consumed. If the slaty 

 structure of the cannel coal belaid along the fire, the piece soon 

 flies to pieces with a crackling noise, and is driven in flames to 

 the furthest corner of the room. Hence the reason why this 

 species is known in Scotland by the name of parrot coal. If the 

 coal be laid on the fire so that its plates are perpendicular to the 

 surface of the grate, it speedily splits into thin plates like the 

 leaves of a book ; but it does not spark out of the fire ; the 

 pieces that would otherwise fly off being intercepted by the 

 direction of the plates. 



Such is a description of the four species of coal known in the 

 neighbourhood of Glasgow, and to which the following experi- 

 ments were confined. 



II. Experiments to determine the Constituents of the four 



Species of Coal. 



It has been hitherto the general opinion of chemists that pit- 

 coal is a combination of bitumen and charcoal. They have 

 endeavoured to determine the proportion of each of these con- 

 stituents by subjecting the coal to distillation. The loss of 

 weight was ascribed to bitumen, and the residual coke was 

 considered as the proportion of the coal which consisted of 

 charcoal. Kirwan formed the same notion respecting the 



