Dr Colquhoun on the Argillaceous Ore of Iron, 31 



what are now fertile corn-fields, in order to supply, at an en- 

 ormous expense, a much more imperfect fuel for the furnace. 

 Nor is it possible to omit contemJ)lating one of the momentous 

 consequences of such an order of things, these subterranean 

 labourers who, in many districts of the island, pursue with in- 

 cessant toil their invaluable occupation. A shaft is sunk, wide 

 excavations are opened up, and tier above tier, at various depths 

 below the surface of the earth, and sometimes below the bed of 

 a river, or of the ocean itself, a succession of extensive sheets 

 are seen to penetrate the bowels of the earth ; so that in a tract 

 of country, which for ages may have been disregarded as an 

 unproductive waste, numerous village^ with their busy throng 

 of inhabitants find an existence which could never have bee^ 

 theirs, but for the fruitful source of wealth which is yielded by 

 the coal mine. And thus it happens, in many parts of this 

 industrious and enterprizing country, that a dense population 

 are making the bosom of the earth to resound with the pick- 

 axe below, while the surface is opened by the plough above, or 

 it may be, is furrowed by the rapid keels which bear abroad 

 the commerce of Great Britain. 



In applying coal to the smelting of ironstone, it is found to 

 be absolutely necessary to reduce it to the form of coke, by 

 keeping it in an ignited condition, until the whole of its vola- 

 tilizable constituents are separated and expelled. This process 

 occasions the loss of a vast quantity of valuable combustible 

 matter, but it is altogether indispensable. It is obvious that a 

 large portion of the heat which is developed during the com- 

 bustion of coal must be absorbed by the liquid and gaseous 

 products which are volatilized from it, and consequently, that 

 the blast-furnace could not possibly be maintained by coal in 

 the same state of ignition as by coke. But, independently of 

 this important consideration, there are circumstances which 

 render the employment of coal in its natural state altogether 

 impracticable. Were it introduced into the furnace without 

 being coked, it would necessarily soften, and run into an entire 

 solid cake, the instant it became ignited. The superincumbent 

 strata of materials would be converted in hke manner into a 

 solid mass, partly in consequence of the condensation of the 

 oily bitumen expelled from the ignited coal, and partly through 



VOL. VIII. NO. I. JAN. 18^. F 



