198 Mr. Vivian on the Process of Amalgamation [March, 



the silver thus reduced to the metallic state, combines with the 

 mercury, forming what is termed amalgam ; whilst the sulphate 

 of soda, the muriate of iron, and other salts, become dissolved 

 in the water. The silver combined with mercury is then 

 filtered, by which the surplus metal is separated, and a com- 

 pound remains in the sack, consisting of six parts of mercury 

 aad one of silver. This amalgam is subjected to the action of 

 heat in a distilUng furnace, by which the mercury is sublimated, 

 and the silver remains. The silver is then collected, and 

 melted in a crucible ; but as it contains a portion of other metals 

 that were combined with it in the ore, it is refined in a cupel or 

 testing furnace. The residue from the barrels is washed in 

 large vessels, and the particles of quicksilver still remaining, 

 are carefully collected. 



Such is the general outline of the processes : I shall now con- 

 sider them in detail. 



The ores selected for amalgamation at Freyberg are of two 

 descriptions; such as contain little or no lead or copper, but 

 yield from 5 to 8 loth of silver in the centner or hundred weight; 

 and stamped ores, that are dressed, clean, and free from earthy 

 particles. Each parcel of ore, when received at the work, is 

 deposited in a separate hutch, and its contents in silver and 

 regule, with the particulars of its component parts, and the mode 

 in which it has been prepared, are carefully noted in an ore book. 

 By this arrangement, the requisite mixture is formed with the 

 greatest accuracy. The quantity of ore thus prepared at one 

 time is 400 centner, which is a week's work for four calcining 

 furnaces. The contents of this lot in silver, should not exceed 

 200 marks. The parcels of ore selected for the general mixture 

 are wheeled from the ore-house, and spread with great nicety 

 over the floor of a spacious apartment, situated immediately 

 over the calcining furnaces. The ore is deposited in layers, of 

 from three to four inches in thickness ; the dry ores are regu- 

 larly intermixed with those from the stamping houses, and a 

 layer of salt is placed over one of ore. The salt, which has 

 been screened to prevent any lumps from remaining, is let down 

 on the ore, by a pipe which communicates with a wooden case 

 on the floor above, formed so as to contain the requisite quan- 

 tity. A heap from 2j to 3 feet in depth is thus formed of alter- 

 nate layers of ore and salt. As each layer is carefully spread 

 over the surface of that beneath it, a regular mixture of the 

 whole is obtained, on being cut vertically through. When the 

 whole has been well mixed, it is separated into portions or 

 charges, of 4 cwt. or two barrow-loads each. These are removed, 

 as it is found necessary, to a part of the room, the floor of which 

 is covered with tiles, and is a little lower than where it was 

 mixed. These charges are laid in separate heaps, ready for the 

 furnaces, which are on the ground-floor, immediately under; so 



