54 GEOLOGY OF ILLINOIS. 



large amount of the heat required for smelting. The furnace is thus 

 kept in operation sixteen hours out of the twenty -four. 



The ore is of different degrees of purity, but the purest galena does 

 not yield on an average over sixty-eight per cent, of lead from the first 

 process of smelting. The gray slag is very valuable, though the lead 

 procured from it is harder than that of the first smelting. There is left 

 about 75,000 of gray slag from each 1,000,000 pounds of ore. The slag 

 furnace is erected under the same roof with the Scotch Hearth, and has 

 a chimney of its own a few feet from that of the hearth, and the "blast" 

 is secured from the same water-power by an additional blast pipe driven 

 by the same wheel. It consists of a much larger reservoir, built of 

 limestone, cemented and lined with clay, with a cast-iron door in front, 

 heavily barred with iron. It will burn cut so as to require repairs in 

 about three months. Open at the top, the slag and fuel are thrown in 

 promiscuously. Under the iron door is an escape for the lead and "black 

 slag." In front of this escape and below it is the "slag pot." It is an 

 oblong iron basin about a foot in depth, with one-third of its length 

 partitioned off to receive the lead, which sinks as it escapes, while the 

 slag, being lighter, flows in a flame-colored stream forward, and falls 

 into a reservoir that is partly filled with water, which cools the slag as 

 it is plunged therein. As the reservoir fills, a workman shovels the 

 scoriae into a hand-barrow and wheels it off. This >scorise is black slag, 

 and worthless, the lead having now been entirely extracted. The 

 smelter now and then throws a shovel full of gray slag into the furnace, 

 which casts up beautiful parti-colored flames, while the strong sulphu- 

 rous odor, the red-hot stream of slag, with the vapor arising from the 

 tub wherein the hissing slag is plunged, the sooty smelters, and the 

 hot air of the furnace room, suggest a thought of the infernal regions. 

 Outside, the wealth of " pigs," not in the least porcine, gives one a sort 

 of covetous desire that, if indulged in, we are taught leads directly to 

 said regions. The Scotch Hearth requires less fuel than any other 

 furnace. It "blows out" in from six to twelve hours, while the Druin- 

 inond furnace was kept in operation night and day. 1 ' 



After examining the process of smelting, I concluded the above de- 

 scription could hardly be improved on, and hence give it a place in this 

 report. 



The Future. The future of the lead region deserves a passing thought. 

 It is an interesting inquiry as to how extensively the mines will be 

 worked hereafter, and how nearly the supply of lead ore is now from 

 becoming exhausted. That the present mines are far from being ex- 

 hausted is well known. Many are temporarily abandoned on account 

 of water. These will doubtless be worked extensively hereafter by 



