1867. 1 Mineralogy, Mining, and Metallurgy. 549 



its own weight in thirty seconds after it was placed in the blast. 

 The powerful heating effects which may be obtained by the uses of 

 pulverized fuel are readily understood when we consider that a cubic 

 inch of coal, reduced to particles one five-hundredth of an inch in 

 diameter, will present to the action of the atmospheric oxygen a 

 surface equal to not less than twenty-one square feet. 



" The calcination of sulphuretted ores, however, requires but a 

 comparatively low temperature, and an abundant supply of oxygen. 

 The fire-tower of the Water Furnace, being heated to redness, the 

 ore, with or without addition of pulverized fuel, is driven by a 

 small fan into the great current of air down the tower ; the sulphur 

 and the base metals are rapidly oxydized and the calcined material 

 falls into the water-tank beneath, while the current of air passes 

 through successive chambers, built over this tank, and open to it 

 beneath. This movement is aided by a large fan-wheel placed at 

 the end of the series, which being furnished with paddles dipping 

 into the water, produces in the final chamber a great amount of 

 spray serving alike to precipitate the suspended dust, and promote 

 the absorption of the sulphurous acid gas. The escape of the excess 

 of this into the air, provided it is not required for further use, 

 is prevented by a second spray-wheel beyond, supplied with milk 

 of lime or some other absorbent. 



" In the case of sulphuretted ores of copper, the water-tank is 

 filled with a solution of the chlorids of sodium and calcium, by 

 which, with the aid of the spray-wheel, the sulphurous acid is 

 absorbed, and the oxyd of copper converted into dichlorid. This 

 beautiful process, devised by Messrs. Whelpley and Storer, I have 

 submitted to examination, and have found that the reaction taking 

 place may be represented as involving one equivalent of chlorid of 

 calcium, one of sulphurous acid, and two of cupric oxyd, and 

 giving rise to one equivalent of sulphate of hme, and one of 

 dichlorid of copper, 



CaCl + S0. 2 + Cu 2 2 = SCa 4 Cu 2 Cl. 



" A solution of chlorid of calcium holding oxyd of copper in sus- 

 pension, rapidly absorbs sulphurous acid gas, and if sufficiently 

 concentrated, is converted into a white crystalline magma of 

 gypsum and dichlorid of copper. This latter salt I find to be 

 soluble in a boiling hot solution of chlorid of calcium, which, how- 

 ever, again deposits it on cooling, a reaction which may probably 

 be found available on a large scale in separating copper from some 

 other metals. In ordinary cases, however, the precipitation of the 

 dichlorid of copper in the furnace-tank is prevented by the presence 

 in the bath of chlorid of sodium, in which, as is well known, the 

 cuprous chlorid is readily soluble. 



" The calcined and oxydized ore falling into the tank, which 



