Mr. F. Forst£r's Observations on the South Welsh Coal Basin. 95 



I may, perhaps, be excused for attempting to describe these peculiar 

 properties a little more in detail. One of the best varieties is procured 

 from the Penprys Seam ("see the section, division No. 2.), the constitu- 

 ent parts of which have already been given. By careful experiments, 

 on a small scale, since verified in the large way, I have ascertained that 

 80 parts of this Coal will convert into steam as much water as 100 

 parts of the best steam-engine Coals of other districts ; an increase of 

 heating power fully accounted for by the appearances exhibited in its 

 combustion in the grate of an engine furnace. A layer of Coals, of 4 

 inches in thickness, when fully ignited, will, by the branching or swell- 

 ing property, expand into a loose heap, 7 oi" 8 inches thick, through 

 every part of which the air has a free passage ; though burning Avith a 

 considerable proportion of thin greenish-yellow flame, it yields no smoke, 

 and, from the free passage allowed to the air, the heat emitted is so in- 

 tense as to consume almost every particle of Cinder, so that the only part, 

 not actually applied in heating the boiler, is a very small proportion of 

 the cinder and the incombustible earthy residuum, which fall through the 

 grate in the form of a grey powder j the total amount of refuse, with a 

 proper grate and skilful management, ought not to exceed 7 per cent. ; 

 The fire ought never to be stirred, and the heat afforded is, therefore, 

 more regular than from any bituminous Coal ; the only attendance re- 

 quired is for the purpose of feeding the fire at proper intervals, and 

 keeping it open at the bottom by letting out the ashes with a small 

 hooked instrument. The advantages of this Coal, in steam navigation, 

 will be at once apparent; 80 tons will answer the purpose of 100 ; it 

 yields less refuse, and requires a chimney less, both in height and area, 

 than other Coals ; and, lastly, it emits no smoke, an invaluable pro- 

 perty as applied to steam vessels engaged in war. Its disadvantages are, 

 that it does not readily ignite at first ; that, except as Culm, and for the 

 purpose of burning Lime, the small produced in working and transfer- 

 ring the Coal is entirely useless ; and that it requires a different system 

 of management, and different sized flues and grates to those in general 

 use ; circumstances too little attended to in burning the various kinds 

 of Coal. 



