670 GEOLOGY AND MINING INDUSTRY OF LEADVILLE. 



used to carry up barrowfuls of old slag used as flux in 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 CO 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 iu 

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

 mixed with about 20 per cent, of milk of lime. 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 If, -ET', with a 

 main sheet-iron flue, F', which enters the brick-dost chambers D' '. Each of the flues 

 H H' 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 iu the sketch), 

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

 F' rests about half way on a small flue-dust chamber, JV, 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 1 are long rows of ore-bins, and immediately behind them is a large 

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

 the fuel level, which communicates with the blast-furnaces by means of an elevated 

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

 mining barrows, is thrown dowu next to the feed-holes along the chutes, 8. This 

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

 all the fuel needed in smelting, but its great inconvenience is that of filling the whole 

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

 toi>reathe and which must prove after a while most injurious to the lungs of those 

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

 GO workmen per twenty-four hours. 



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

 shape, dimensions, and capacity. Both furnaces are seen in perspective, Plate XXV, 

 and one of them is drawn to scale iu Plate XXIII. They are constructed on exactly 

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

 a good deal. 



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

 cast-iron plates, a, 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-irou plates, 

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

 larly framed. The crucible, siphou-tap, fore-hearth, and fore-hearth projection are 

 entirely lined with steep, made of one 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, a', bolted to the cast-iron' plates of 

 the crucible. The system of water-jackets consists of six jackets of equal dimensions; 

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



