670 GEOLOGY AND MINING INDUSTRY OF LEADVILLE. 



used to carry up barrowfnls of old slag used as flux iu smelting. The boiler, engine, 

 and blast room is next to the furnace-room, on the right facing the furnaces. The 

 boilers are worked at a pressure of 60 pounds per square inch. The engine is of 40 

 horse-power and the blast apparatus consists of two No. 5 Baker blowers. 



The offices, assay offices, and laboratory occupy detached buildings on a level 

 with the foot of the slag-heap. On the feeding-floor is a large wooden trough in 

 which the roasted flue-dust (at this smelter flue-dust is roasted before resmelting) is 

 mixed with about 20 per cent', of milk of lune. The mixture is then spread over the ore- 

 beds placed on this floor. The crushing machinery, placed also on this floor, consists 

 of two large No. 5 Blake crushers (opening between the jaws, 15 by 9 inches). 



Immediately outside of the main building, on the feeding-floor level, are the flues 

 connecting. the stack of the furnaces with the dust-chamber; this arrangement is the 

 only one of its kind in Leadville. The upper part of the stacks E, E', (Plate XXV) 

 of the furnaces A, A', are connected by means of the sheet-iron flues H, H', with a 

 main sheet-iron flue, F', which enters the bi'ick-dust chambers D'. Each of the flues 

 HE' is provided with one, and flue F' with three, sliding doors, placed on the upper 

 part of the flues and parallel with them (these doors are not visible in the sketch), 

 and used for clearing the dust which accumulates periodically iu the flues. The flue 

 F' rests about half way on a small flue-dust chamber, N, made of bricks and provided 

 with a sliding door, d, for the extraction of the flue-dust. Immediately at the rear of the 

 dust chamber D' are long rows of oi'e-bins, and immediately behind them is a large 

 roastingfurnace. The level immediately above and at rear of the roasting-furnace is 

 the fuel level, which communicates with the blastfurnaces by means of an elevated 

 platform, R', ])rovided with a track of rails. The fuel, charged in light sheet-iron 

 mining barrows, is thrown down next to the feed-holes along the chutes, S. This 

 arrangement is capital and saves much labor; two fuel men are sufticieut to supply 

 all the fuer needed iu smelting, but its great inconvenience is that of tilling the whole 

 feeding-floor with an ever-floating cloud of impalpable charcoal dust, very disagreable 

 to breathe and v.'hich must prove after a while most injurious to the lungs of those 

 who live constantly in such an atmosphere. When in full blast these works employ 

 66 workmen per twenty-four hours. 



Furnaces — The two blast-furiiaces at Smelter A are circular and identical in 

 shape, dimensions, and capacity. Both furnaces are seen iu perspective, Plate XXY, 

 and oue of them is drawn to scale iu Plate XXIII. They ai-e constructed on exactly 

 the same general principles as all the other furnaces in the camp, but in detail difle: 

 a good deal. 



The crucible A is very little larger than the water-jackets; it is framed in strong 

 cast-iron plates, «, forming segments of a circle, six in number and firmly bolted to- 

 gether at the joints. The frame of the fore-hearth X is also made of cast-iron plates, 

 and the projection X" of the fore-Iieartb, which exists only in this furnace, is simi- 

 larly framed. The crucible, sii)hou-tap, fore-hearth, and fore-hearth projection are 

 entirely lined with steep, made of oue part fire-clay and one part finely pulverized 

 coke. The projection of the fore-hearth is provided with two slag-spouts, U. The 

 frame of the lead-pot is made of strong sheet-iron, «', bolted to the cast-iron' plates of 

 the crucible. The sj'stem of water-jackets consists of six jackets of equal dimensions; 

 four of these are made of strongly riveted, wrought-iron boiler-iilates and two are made 



i 



