680 GEOLOGY AND MINING INDUSTRY OF LEADVILLB. 



Plate XXXII), aud are connected with the dust-chamber represented in Fig. i. A 

 longitudinal or side elevation of the fui-nace, shown in front elevation in Fig. 1, is seen 

 in Fig. 3. The hearth A is very similar to that of the furnaces at Smelter C, already 

 described; it is lined with firebrick, and the siphon-tap Lis contined within the hearth- 

 plates: but here the bullion is ladled out direct from the siphon-tap. The hearth- 

 plates are braced by one row of braces, Q'. The hearth is also confined within the 

 hearth-plates, as was the case at smelter 0, and does not project out, as in other fur- 

 naces. Tlie water-jackets B are made of inveted steel boiler-plates and are braced by 

 tie-rods Q. There aro only four jackets: one in front, one at back, and one large one 

 on each side. The circulation of water in these jackets is similar to the one adopted 

 with cast iron jackets; the water is introduced by means of the pipe M, and the hot 

 water comes out at the open outlets i?, provided with outlet-pipes 8. The back water- 

 jacket is provided with two tuyere-holes, which are not used, and the side jackets with 

 four holes, in each of which a tuyere is placed; so that each furnace is worked with 

 eight tuyeres. 



The pillars P do not rest on the ground, as is the case with all the furnaces thus 

 far described, but on the lining of the crucible. Another peculiarity is that there are 

 six of these pillars, instead of four as in most furnaces. The capitals are supported 

 on the pillars by means of brackets t. The main cast-iron plate support is of unusual 

 thickness, being four inches thick. The use of a plate of such unusual dimensions 

 is necessitated by the fact that the luasonry does not rest directly on the pillars, as in 

 other furnaces. 



The ma.soury consists of fire bricks, as usual, but is entirely surrounded by a 

 wrought iron jacket, J'. At the throat there art two feed-holes H, provided with slid- 

 ing doors iS". 



Dust-chamber. — The sheet iron stack of each furnace, which is a prolongation of 

 the jacket, is connected by means of the flues F' F" with the sheet-iron dust-chamber, 

 formed of a cylindrical portion D' aud a conical portion I>". The fumes escape through 

 the sheet iron stack. The dust is withdrawn from this chamber by means of sliding 

 valve (S', and falls from the aperture Z into a wheelbarrow, Y. At smelter D flue-dust 

 is not mixed with lime, as at most smelters, nor spread over ore-beds or mixed with 

 smelting charges; it is simply moistened with water and thrown in the furnace in the 

 ]>roportion of one shovelful to every two smelting charges. The smelting capacity of 

 each furnace is 24 tons of ore per 24 hours, or one ton per hour. The iiressure in 

 blast-pipe R' is regulated by a damper placed at its extremity. The length of runs at 

 this smelter is about two months. 



Smelter E. 



Disposition of works.— These v.'orks, situated on Big Evans gulch, are, like all the 

 smelters erected on this gulch, divided into two levels only. This smelter is small, but 

 well managed, and is one of the most successful of its size. The pressure of the steam 

 in the boilers is 70 pounds to the square inch; they supply a 40 horse-power engine, 

 which drives two Baker blowers, a set of Cornish rolls, two Blake crusliers, and the 

 pumps feeding the water tanks. The ore aud fuel bins are inclosed in the main build- 

 ing, through which runs a wagon-road, and fuel reserves are placed at the back, out 

 side of the works. The offices, provided with Fairbanks scales, and the laboratory are- 

 sitnated in a detached building a short distance back of the maiu building. 



