202 MINING INDUSTEY. 



The quicksilver charged with amalgam is carefully cleaned by washing 

 with water and removing from the surface the associated impurities such as 

 heavy particles of dirt, pyrites, &c. In some cases the cleaning is performed 

 in a small iron pan, resembling the settler in manner of construction but much 

 smaller, in which it is stirred slowly with plenty of clean water, which serves 

 to wash out the impurities and remove them from the pan. When properly 

 cleaned the amalgam is strained through a canvas filter or conical bag, 10 or 

 12 inches in diameter at the top, and 2 or 3 feet long. (See Fig. 8, Plate 

 XVIII.) The quicksilver is drained off and returned to the pans for further 

 use, while the amalgam is thus obtained for the retort. 



In some mills this straining is not performed after every charge of ore, 

 as is the case in others, but only at stated times, say once in twenty-four 

 hours, or once in three or four days. Under such circumstances a consider- 

 able quantity of quicksilver is kept in the settler, sometimes 200 or 300 

 pounds. This excess of quicksilver, holding the amalgam in solution, is in a 

 highly fluid condition, and when discharged from the settler by means of the 

 tube and cistern just described, it is returned to the pan for further amal- 

 gamation, its "charged" condition — that is, having silver already in combina- 

 tion — ^being considered an advantage, as it is thought to be more active than 

 pure metal in the amalgamating process. In some mills, at a stated hour of 

 each day, the quicksilver coming from the settlers is strained and the amal- 

 gam extracted ; in others, as the quicksilver thickens or becomes sluggish by 

 the accumulation of amalgam, it is diluted by the addition of fresh quick- 

 silver, and the straining of the amalgam is only made once in several days 



From time to time, as at the end of the month or other given period, 

 or when any special lot of ore has been finished, of which it is desired to 

 know the exact yield, the pans and settlers must be stopped and cleaned up 

 thoroughly. For this purpose the mullers must be raised, the shoes and dies 

 removed from their places, and all the iron work of ;the pans and settlers care- 

 fully scraped with a knife to remove and collect the hard amalgam which 

 attaches itself to such surfaces. In many cases one-fourth or even a greater 

 proportion of the total product of amalgam is obtained in this way. 



Retorting and Melting. — The amalgam, having been strained in the 

 bags and forcibly pressed, in order to expel as much of the fluid quick- 



