718 



GOLD 



The Importations of Gold into the United Kingdom, in other forms, arc. given as follow : 



Gold, Mctatturgic Treatment of. The gold found in the sands of rivers, or in auri- 

 ferous soils, need not be subjected to any metallurgic process, properly speaking. The 

 gold seekers separate it from the sands, by washing them first upon inclined tables, 

 sometimes covered with a cloth, and then by hand in wooden bowels of a particular 

 form. The methods of working vary in different localities. The people called Bohe- 

 mians, Cigans, or Tehinganes, who wash the auriferous sands in Hungary, employ a 

 plank with 2-1 transverse grooves cut in its surface. They hold this plank in an 

 inclined position, and put the sand to be washed in the first groove ; they then throw 

 water on it, when the gold, mixed with a little sand, collects usually towards the 

 lowest furrow. They remove this mixture into a flat wooden basin, and by a peculiar 

 sleight of hand separate the gold entirely from the sand. The richest of the 

 auriferous ores consist of the native gold quite visible, disseminated in a gangue, but 

 the veins are seldom continuous for any length. The other ores of this district are 

 auriferous metallic sulphides, such as sulphides of copper, silver, arsenic, &c., and 

 particularly iron. 



The stony ores are first ground in the stamping mill, and then washed in hand- 

 basins, or on wooden tables. 



The auriferous sulphides are much more common, but much poorer than the former 

 ores ; some contain only one 200,000th part of gold, and yet they may be worked with 

 advantage, when treated with skill and economy. 



The gold of these ores is separated by two different processes ; namely, by fusion 

 and amalgamation. 



The auriferous metallic sulphides arc first roasted; then melted into matte*, which 

 are roasted anew ; next fused with lead, whence an auriferous lead is obtained, which 

 may be refined by the process of cupellation. 



When the gold ores are very rich, they are molted directly with lead, without pre- 

 liminary calcination or fusion. These processes are however little practised, brraui-o 

 they are less economical and certain than amalgamation, especially when the gold-ores 

 are very poor. 



If these ores consist of copper pyrites, and if their treatment has been pushed to the 

 point of obtaining auriferous rose-copper, or oven black copper including gold, the 

 precious metal cannot be separated by the process of liquation, because the gold having 

 more affinity for copper than for lead, can bo but partially run off by the latter md a I. 

 For those reasons the process .of amalgamation ie far preferable. This process bring 

 the same for silver, wo reserve its full description for that metal. See SII.YKU. 



The rich ores in which the native gold is apparent, .and .merely disseminated in a 

 stony gangue, are directly triturated with quicksilver, without any preparatory opera- 

 tion. As to the poor ores, in which the gold seems lost amid a great mass of iron, 

 sulphide of copper, &c., they 'are subjected to a roasting process before being amal- 

 gamated. This process seems requisite to lay bare the gold enveloped in the sulphurots. 

 The quicksilver with which the ore is now ground seizes the whole of its gold, in how- 

 ever small quantity this metal may be present. 



The gold produced by the refining process with lead is free from copper and lead. 1 >ut 

 it may contain iron, tin, or silver. It cannot bo separated from iron and tin without 



