X)r Colquhoun on the Argillaceous Ore of' Iron. 85 



It is very frequently penetrated by vertical foliae of earthy 

 or siliceous matter, of various thickness, and it also appears to 

 be more subject to contamination by iron pyrites than the 

 splint coal. 



Although cherry coal, when burnt in the open air, has lit- 

 tle or no tendency to agglutinate or run into a cake, yet it is 

 always found to be converted into a uniform mass, in the pro- 

 cess of coking, just as if the whole had consolidated after hav- 

 ing been in a state of complete fusion. Its coke possesses 

 the following properties. It is light, of an open and vesicu- 

 lar texture internally, much more liable than that of the splint 

 coal to shiver, and crumble into &mall fragments, and it is ex- 

 tremely combustible. Owing to its porousness and combustibili- 

 ty, it cannot resist, for any length of time, the action of a strong 

 blast furnace ; and, for many years past, it has been the practice 

 in Scotland to throw the air from the condenser with very 

 great power into the furnace, with a force indeed that is equi- 

 valent to the pressure of a column of mercury of 6 or 8 inches, 

 so that the use of coke from cherry coal is quite inadmissi- 

 ble. It would be consumed in the inteilse heat of such a 

 blast, long before it had effected the complete reduction and 

 supercarburation of the iron. But as this species of coal is by 

 far the most abundant in the country, it seems to be by no 

 means improbable, that it may yet come to be employed in 

 the reduction of the less refractory ores, for which a blast 

 produced by a more moderate pressure will of course suffice. 

 It might probably be rendered available, also, in the manu- 

 facture of those kinds of cast-iron at a low degree of carbura- 

 tion, which are intended to be afterwards decarburetted, and 

 converted into malleable iron. 



The coke of the splint coal is the only one which can be 

 used with advantage in the blast furnace, as it is at present 

 managed in this country. The splint is, in its general ap- 

 pearance, the least beautiful of all our coal. Its colour is 

 greyish or brownish black ; its lustre is, for the most part, 

 comparatively dim, as the fractured surface is frequently of a 

 dull and earthy aspect. The fracture is even, or nearly so, 

 and the fragments into which it breaks are of an angular or 

 indeterminate form. The genuine splint coal has no disposi- 



