CENTEAL AND EASTEEN NEVADA. 379 



muller in this process seldom exceeds six months, and sometimes is only three. 

 The charge is worked six hours. Quicksilver is not generally supplied to the 

 pan until after the charge has been working some time, so that the metallic 

 chlorides may be decomposed by the iron, rather than at the expense of the 

 quicksilver. The quantity employed is adapted to the richness of the ore. For 

 ores worth $200 per ton, 250 pounds of quicksilver are used, which quantity is 

 increased with ores of greater value. After six hours' treatment in the pan 

 the charge is passed into the settler or separator. This is generally like those 

 already described, and serves a similar purpose. The pulp is thinned and cooled 

 by the addition of water, and gently agitated by a muller which revolves 

 slowly, carrying wooden shoes, or stirrers. The fluid amalgam, collected in the 

 settlers, is strained, and the solid portion retorted. The amalgam that collects 

 on the mullers of the pans is removed from time to time, cleaned up in a small 

 iron pan, and likewise retorted. About one-fifth part of the amalgam obtained 

 from the pans and settlers is bullion, which is melted and run into bars for ship- 

 ment. The bullion is usually yso% to ^VA fi^^e. It contains no gold. The 

 impurity is chiefly copper. The retorting furnace is similar to that which has 

 been already described. The loss in quicksilver in this mill is stated at one 

 pound and a half per ton of ore worked. 



The yield obtained from the ore is from 85 to 90, and sometimes a still 

 higher percentage, of the assay value. 



The power for driving the machinery of the mill is furnished by a steam- 

 engine, horizontal cylinder, 42 inches in diameter and 1 8 inches stroke, to which 

 two tubular boilers, 50 inches in diameter, supply steam. They consume about 

 six cords of wood per day. The total consumption of wood per day for the 

 mill, including steam, roasting furnaces, retorts, &c., is about 18 cords. It 

 costs from $9 50 to $10 per cord. 



The men employed during a day of twenty-four hours, two shifts, are as 

 follows : 



Foremen, one each shift 2 



Mechanics 2 



At the rock-breaker and drying-floor, three by day, two by night 5 



At the batteries 3 



Supplying ore from the batteries to the furnaces 3 



