232 PLYMOUTH INSTITUTION. 



He next entered upon coal, which was described as of three 

 classes : — wood coal, flaming coal, and culm or anthracite. 



The wood coal pit at Bovey — that field was then described. 

 Wood coal was a more effective fuel than turf, but still very 

 inferior to flaming coal. It gave out an offensive smell, and 

 yielded about 8 per cent, of ashes. Like turf, much of it is 

 converted into ulmine, and dissolves in alcali. It was chiefly 

 used at a little pottery at Bovey, but had been tried, unsuccess- 

 fully, for smelting the Haytor iron ore; which, however, he 

 thought it would be equal to, with proper management. 



Lignite also yielded an excellent charcoal, much resembling 

 that from wood, and in larger proportion; which burnt with a 

 strong lively heat, and without the smell of the fresh coal. It 

 would answer all the purposes of oak charcoal, if attention were 

 paid to the discharge of the ashes. 



Flaming coal was of four kinds : — 



1, Caking coal, such as we get from Newcastle. 



2, Splent coal, a harder and duller kind, more like the Welsh 

 coal, but different in some respects. 



3, Cherry coal, the Scotch coal used on board the steam 

 packets. 



4, Cannel coal. 



The first and last were described as best suited for common 

 grate fires and gas works ; the two others for furnaces* work. 



The geological position of coal, and its probable origin were 

 explained ; and descriptions given of the methods of mining and 

 raising it. Allusion was made to the apprehensions expressed, 

 by some persons, of the coal running short, and putting a stop to 

 our machinery : and a calculation was gone into, from whence 

 it appeared that the quantity now in store, under ground, amoun- 

 ted to about eighteen thousand millions of tons; which, at the 

 present rate of consumption, would last nearly 1,000 years. 



Different analyses of coal were then given, and corrected by 

 computation from the average produce of gas works — taken at 



Gas, 10,000 cubic feet -x 



Tar, 160 pounds # Which gave the 



Ammoniacal ) ^.^ , > elements quo- 



Liquor \ 200 pounds t ^^d in the table. 

 Coke, 18 cwt. J 



From a Chaldron of Coals, weighing 27 cwt. 



The uses of coal were stated to be innumerable ; in short, to 

 be estimated only by the demand for heat, or for mechanical 



