PLANT OF SMELTER G. 685 



per tweutyfour hours. The luauipuhitious of either furuace do not ditfer from those 

 in (ISO at other smelters. The shovels used are represented in Figs. 2 and 3, Plate 

 XLIV, and the bars of bullion iu Figs. 5 and C, Plate XLY. 



Dust-chambers and ventilation lu Fig. 1, PlatC XXXVJ, is shown the general 



system of condensation of lead fumes and of ventilation of the furnace-room. The ven- 

 tilators V V" V" consist of large rectangular sheet-iron chimneys resting on the brick 

 dust-chambers D' D" J)'". They are open at their base on the side towards the furnaces 

 to allow hot air to escape through them. Besides the ventilators each furuace is pro- 

 vided with a hood and chimney in front of the furuace towards the slag-giitters. 



Furnace A is connected by means of sheet-irou tluei^' with chamber D', divided 

 into three sectious, a, b, c, by means of partition walls n; and the smoke escapes through 

 the sheet-iron stack S. 



Furnace B is similarly connected through flue F" with chamber D", divided into 

 three sections, a', h', c', by means of walls iv', the smoke escaping through sheet-iron 

 stack S." 



Furnace C is connected by means of sheet-iron flue F'" with a brick chamber, d', 

 8 feet high and 11 by 11 feet at base, resting on the feeding-floor P' P'. This chamber 

 has an independent sheet-iron stack, S'. 



Furnace D communicates by means of sheet-iron flue F'" with chamber IJ'", 

 divided into two sections a", b", and ihe fumes circulate through the brick flue C", 

 25 feet long, and then asceiid the square brick stack S'". Each section of the dust- 

 chambers is provided with sliding doois d, for the extraction of the dust; those of 

 sectious c' and a" of chainbers B" and D'" are in the arch-way 0. 



At smelter G flue-dust is mixed wilh argillaceous ores and resmelted. 



Smelting charges — The following flgures show the smelting performed by the three 

 small furnaces at smelter G from the IJlb of June, 1879, to the 1st of January, 1880: 



Ore smeltecl, 24,094,177 pounds = 12,047 tons, assaying 73^ ounces silver; lead, 22 per ci-nr. 



Dolomite, 1,521,085 pounds ^ G. 31 per cent, of ore smelted. 



Hematite, 2,872,.535 pounds =^ 11.92 per cent, of ore smelted. 



Coke, 1,986,110 2ionnds^ 8.25 per cent, ol ore smelted ) Fuel := 24.5 per cent, of ore 



Charcoal, 3,916,287 pounds = 1G.25 per cent, of ore smelted ) smelted. 



The contents were: Silver, 8S5,4ji ounces ; lead, 5,300,719 jjounds. The products 

 amounted to: Silver, 8G0,GG(] ounces ; lead, 4,169,823 pounds. 



The loss in silver was 2.12 per cent, and in lead 15.67 per cent. 

 The average price paid per ton of ore was 866.15. 

 The bulliou produced each day, 12^ tons. 



Disposition of works — Smelter H is the most important smelter of Big Evans gulch. 

 These works are iu close proximity to the important mines of Fryer Hill, and the ores 

 they receive comprise some of the richest iu lead, gold, and silver. The bullion extracted 

 there is also generally very rich in silver. The works are jirovided with a laboratory, 

 in which the ores are assayed, chiefly by scorificatiou, but some mines require also the 

 crucible assay. The crucible assays of ore for silver and of ores and slags for lead are 

 made only with reducing flux, and no iron rods are used for the reduction of sulphurets 



