SIX MONTHS IN MEXICO. 



105 



piled in heaps of a ton or more in each, and 

 then mixed with salt, sulphate of iron, lime, 

 vegetable ashes, &c. A quantity of mercury 

 in proportion to the calculated quantity of 

 silver, is then added, and suffered to remain for 

 some time, the whole being turned or worked 

 together by Indians treading it with their feet. 

 When they suppose the mercury has entirely 

 united with the ore, it is put into vats, over 

 which a stream of water passes : the amalga- 

 mated ore is then stirred up, the earthy part 

 carried off by the stream, and the mercury, 

 incorporated with the silver, remains at the 

 bottom. The silver is afterwards separated 

 from the quicksilver by means of fire, with a 

 considerable loss. It has been proved by ex- 

 periments lately made in Cornwall on ore sent 

 from Mexico for the purpose, that the same, 

 or nearly the same process that is used in 

 smelting tin, may with considerable advantage, 

 be applied to the more valuable metal of silver, 



