314 RESOURCES OF CALIFORNIA. 



by quicksilver. The board-sluice was for a time the great 

 washing machine, and the most important instrument used in 

 the placer mining of California. It \vashed nearly all the dirt, 

 and caught nearly all the placer gold. It was invented here, 

 although it had previously been used elsewhere ; and it has 

 been more extensively employed here than in any other country. 

 It is not less than fifty feet long, nor less than a foot wide, 

 made of boards. The width is usually sixteen or eighteen 

 inches, and never exceeds five feet. The length is ordinarily 

 several hundred, and sometimes several thousand feet. 



235. Pan. The pan is used in all branches of gold min- 

 ing, either as an instrument for washing, or as a receptacle for 

 gold, amalgam, or rich dirt. It is made of stiff tin or sheet- 

 iron, with a flat bottom about a foot across, and with sides six 

 inches high, rising at an angle of forty-five degrees. A little 

 variation in the size or shape of the pan will not injure its 

 value for washing. Sheet-iron is preferable to tin, because it 

 is usually stronger and does not amalgamate with mercury. 

 The pan is the simplest of all instruments used for washing 

 auriferous dirt. Some dirt, not enough to fill it full, is put in, 

 And the pan is then put under water. The earthy part of the dirt 

 !s rapidly dissolved by the water, assisted by the shaking of the 

 ipan and the roiling of the gravel from side to side, and forms a 

 nud, which runs out while clean water runs in. The light 

 and flows out with the thin mud, while the lumps of tough 

 ilay and the large stones remain. The stones collect on the 

 op of the clay, and they are scraped together with the fingers 

 md thrown out. This process continues, the pan being grad- 

 lally raised in the water, and its outer edge depressed, until 

 ill the earthy matter has been dissolved, and that, as well as 

 ,he stones, swept away by the water, while the gold remains at 

 -he bottom. Panning is not difficult, but it requires practice 

 :o learn the degree of shaking which dissolves the dirt and 

 throws out the stones most rapidly without, losing the gold. 

 Amalgam can be separated from dirt, by washing, almost as 



