672 GEOLOGY A^'D MIXING INDUSTRY OF LEADYILLE. 



terual dlspositiou of tbo fuiuace. This roastiug-funiace is used at Smelter A for roast- 

 jug' tbe cbatnber dust previous to resnieltiug. lu the study of metalhirgical products 

 it will be seeu that it is au expensive aud useless operatiou, aud tUatit were better, ou 

 the coutrary, to use it for the roasting of mattes aud speiss. The former, beiug roasted 

 iu heaps, lose a great deal of their silver, aud the latter is uot treated iu Leadville. 

 The ouly poiut of interest iu the roastiugfuruace of Smelter A is the flue C, iu which 

 a good deal of the products volatilized duriug the roasting is coudeused; so that this 

 furnace is admirably ada])ted for the treatment of matte, accretions, and speiss, all 

 products containing a good deal of silver. iS represents the stack of the furnace ; G, 

 the damper of the stack. The ash-pit of the furnace is uot visible, but is placed at h. 



Disposition of works — These works, the largest aud most important iu or near 

 Leadville, are situated iu Leadville proper, ou 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 iu 12 hours. 



The old slag-heap, placed immediately in frout of the furnaces, is being eutirely 

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

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

 heap is placed in direct commuuicatiou 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 ou the feediug-tioor. 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 irou truck running on a tramway resting jiartly on 

 the ground in front of the woi'ks, partly on a timber bridge projecting over the gulch, 

 aud being taken to the end of the bridge are dumped into the gulch. Tbe maiu smelt- 

 ing buildiug at smelter B is 212 feet by 91 feet. Tbe ore-bius are placed ou the feed- 

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

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

 chaicoal bins aie 150 by IS feet. Large heaps of dolondte, 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 oftice at the entrance of the works. 

 The oflices, assay oBices, aud laboratory occupy a detached building. In the well-fitted 

 laboratory, besides the current assays made, tbe 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. 



jSTiue Baker blowers, standing iu 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, tbe slag-hoisting machine, and the pumps supply- 

 ing tbe tanks from which the water-jackets are fed, are worked by two eugines, li 

 by 21 inches, of GO horse ])Ower each. Each engine is connected with two boilers, 

 4-1 inches by 14 feet, worked at a i)ressure of 70 pounds to the square inch. Both en- 

 gines and boilers were nmuufactured by Messrs. Eraser & Chalmers. The engine and 

 boiler rooms stand ou the left of the works (facing tbe furnaces), nest to the furnaces 

 aud ou a level with them. 



