MINING. 247 



the particles of gold are so coarse in amalgam that they can 

 easily be strained out by means of buckskin or tight cloths. 

 However a little gold will remain in the quicksilver — about 

 the fiftieth part of an ounce of gold in every pound of quick- 

 silver ; and the only method of obtaining this gold is by re- 

 torting. 



Quicksilver is used in gold mining for catching the small 

 particles of metal ; the large ones are caught by their weight. 

 But many of the particles are so small that they are almost in- 

 visible to the naked eye, and when in moving water they 

 float. Miners frequently show visitors the fineness of their gold 

 by putting some of the dust in a vial with water ; and upon 

 shaking, the particles of metal can be seen floating about in 

 the clear water. Riffles, and all the devices to get the benefit 

 of specific gravity, are of httle use to arrest this " float-gold," 

 so amalgamation is employed. If a bit of quicksilver is put in 

 the w^ay of the fine gold, the two metals unite at once and 

 make a larger bulk, which can be caught. 



There is no such attraction between gold and quicksilver as 

 there is between the magnet and iron ; but when the two for- 

 mer metals once touch, an amalgam is immediately formed, and 

 if the proportions of the metals be about even, they in time 

 make a hard mass. Some gold does not amalgamate readily ; 

 in various diggings of Siskiyou county, the gold has a red- 

 dish coating, which prevents amalgamation. Grease or resin 

 in the water used for washing, is also unfavorable. So is cold. 

 Heat is favorable, and therefore less gold is lost in summer 

 than in winter. Quicksilver that has been once used is consid- 

 ered better than tliat fresh from the flask. 



No tinned iron or copper vessel should be used for holding 

 or panning out amalgam, or dirt containing amalgam ; since 

 quicksilver forms an amalgam with tin and copper, and will 

 stick to the sides of a tinned or copper pan. 



In most sluices, the quicksilver is put in above the riffle- 

 bars at various places along in the boxes, with a confidence 

 that the great specific gravity of the metal will prevent it from 



