268 MINING INDTJSTEY. 



the addition of water, and the quicksilver and amalgam are thus allowed to 

 collect on the bottom of the barrel. 



Below the barrels is a large hopper or funnel-shaped contrivance, sloping 

 down from the four sides to a common center. When a barrel is to be dis- 

 charged, a small plug in the side is loosened while turned upward, and when 

 the barrel is revolved, so that the plug is downward, it is drawn out by hand. 

 The quicksilver and amalgam are discharged into the hopper or funnel just 

 described, and are allowed to run from the barrel until the pulp begins to fol- 

 low, when the plug is rej)laced. When all the barrels, ready for that purpose, 

 are discharged, the amalgam in the hopper is carefully collected and washed, 

 and afterward cleaned in a common pan like those in use in other mills for 

 similar purposes. The straining of the quicksilver and retorting of the amal- 

 gam is performed in manner similar to that already described. 



After the hopper below the barrels has been cleaned of all the quicksil- 

 ver discharged into it, the residue is permitted to flow from the barrels and to 

 run down into a large agitator, eight or ten feet deep, and twelve or fifteen feet 

 in diameter, in which stirring-arms are revolving in manner similar to that 

 already described in the foregoing. By this means, the unseparated quicksil- 

 ver and amalgam are allowed to settle, and the concentrations of this vessel 

 are worked over in pans in the common way, while the mass of tailings, pass- 

 ing from the settler, are subjected to further methods of concentration and 

 subsequent treatment. 



The actual costs, in detail, of the treatment of ore by this method, or 

 the actual percentage of value obtained from the ore, are not definitely known 

 to the writer. The former probably vary between $20 and S30 per ton, ac- 

 cording to the richness of the ore, the amount of salt, quicksilver, and other 

 material consumed, and other conditions.^ The only mill now employed in 

 the reduction of high-grade ores produced by the Comstock charges the pro- 

 ducer 840 or $45 per ton for treatment and guarantees the return of eighty 

 per cent, of the assay value of the ore. The supply of ore is so limited, and 

 the establishment consequently unoccupied for such a proportion of the time, f 



'"VYood costs, per coiclj $5; common labor, per day, |3; salt, per pound, 3 cents; 

 quicksilver, per pound, 65 cents. 



