672 GEOLOGY AND MIXING INDUSTKY OF LEADV1LLE. 



ternal disposition of tbe furnace. This roasting-furnace is used at Smelter A for roast- 

 ing the chamber dust previous to resmeltiug. In the study of metallurgical products 

 it will be seen that it is an expensive and useless operation, and th'atit were better, on 

 the contrary, to use it for the roasting of mattes and speiss. The former, being roasted 

 in heaps, lose a great deal of their silver, and the latter is not treated in Leadville. 

 The only point of interest in the roasting-furuace of Smelter A is the flue C, in which 

 a good deal of the products volatilized during the roasting is condensed; so that this 

 furnace is admirably adapted for the treatment of matte, accretions, and speiss, all 

 products containing a good deal of silver. 8 represents the stack of the furnace ; 0, 

 the damper of the stack. The ash-pit of the furnace is not visible, but is placed at h. 



SMELTER B. 



Disposition of works These works, the largest and most important in or near 

 Leadville, are situated in Leadville proper, on the northern bank of California gulch 

 and facing the gulch. With their 118 men at work in a .somewhat limited space they 

 present an unusual amount of bustle and activity and smelt about one hundred tons 

 of ore in 12 hours. 



The old slag-heap, placed immediately in front of the furnaces, is being entirely 

 dug up, in order to be resinelted. These slags were made formerly of siugulo-silicates, 

 but now the slags contain a little more silica, and are called acid slags. The old slag- 

 Leap is placed in direct communication with the feeding-floor by means of an inclined 

 tramway supported by timber trestle-work, on which a mine wagon is run by a wire 

 rope which winds over a drum placed on the feeding-floor. The new slags made at these 

 works are allowed to solidify in the pots; they are detached while hot, lifted by means 

 of a small crane, placed on a small iron truck running on a tramway resting partly on 

 the ground in front of the \\ orks, partly on a timber bridge projecting over the gulch, 

 and being taken to the end of the bridge are dumped into the gulch. The main smelt- 

 ing building at smelter B is 212 feet by 94 feet. The ore-bins are placed on the feed- 

 ing-floor within this building, where are also placed the ore-beds, crushers, Cornish rolls, 

 etc. The coke-room, at the back of the main building, is 200 feet by 20 feet and the 

 charcoal- bills are 150 by 18 feet. Large heaps of dolomite, hematite, and large dumps 

 of low-grade ore fill up the open space at the rear of the works. Large Fairbanks 

 scales, of a capacity of 20 tons, occupy a detached office at the entrance of the works. 

 The offices, assay offices, and laboratory occupy a detached building. In the well-fitted 

 laboratory, besides the current assays made, the specific gravity of slags is determined 

 from day to day. The slags are considered fit to be thrown away when their specific 

 gravity is 3.0. 



Nine Baker blowers, standing in a row under the feeding-floor and at the back 

 of the furnaces, supply the blast. These, as well as three Blake crushers, three sets of 

 Cornish rolls, one small pulverizer, the slag-hoisting machine, and the pumps supply- 

 ing the tanks from which the water-jackets are fed, are worked by two engines, 14 

 by 24 inches, of 00 horse-power each. Each engine is connected with two boilers, 

 44 inches by 14 feet, worked at a pressure, of 70 pounds to the square inch. Both en- 

 gines and boilers were manufactured by Messrs. Fraser & Chalmers. The engine and 

 boiler rooms stand on the left of tbe -works (facing the furnaces), next to the furnaces 

 and on a level with them. 



