1826.3 fls carried on in GermanT/. 197 



blishment, the extreme neatness and cleanliness with which it 

 was kept, and the skill and science with which the processes 

 were conducted, together with the civility and attention of the 

 agents and workmen, I took a peculiar interest in the establish- 

 ment, and frequently visited it during my residence in the neigh- 

 bourhood. 



It may be well to give a general outline of the processes, 

 before I enter on the details, that the connecting links of the 

 system may be understood. 



The first operation that requires description is the selection of 

 ores to form a proper mixture, with reference to the quantity of 

 silver and sulphur they contain. This is a most material point 

 to be attended to. It has been before observed that the amal- 

 gamation process succeeds best, when the silver produce is about 

 7-i loth in the quintal of ore, or about 75 ounces in the ton. 

 The object, therefore, is, by a selection of different ores, to bring 

 the whole as near to this average as can be conveniently 

 eflfected ; at the same time regard being had to the proportion of 

 sulphur contained in them. This is estimated by the quantity 

 of regule, or sulphuret, found in the ore ; which is ascertained 

 by an assay in the crucible. The standard by which they are 

 governed is, that a proper mixture of the different ores gives 35 

 per cent, of regule ; about one-half of which, or perhaps rather 

 more, may be sulphur. But as the silver in the Freyberg ores 

 is rarely in the metallic state, at least in any quantity, it becomes 

 necessary to detach it from its combination with sulphur or 

 other substances, before subjecting it to the actual process of 

 amalgamation ; as otherwise these substances would prevent its 

 union with the mercury. This is done by adding to the mixture 

 of raw ore, 10 per cent, of common salt, or muriate of soda ; by 

 which, during the operation in the furnace that follows, a che- 

 mical change is effected. The sulphur becomes acidified, and 

 the acid thus formed, uniting with the base of the salt, forms 

 sulphate of soda ; whilst the muriatic acid thus set free, combines 

 with the silver ia the ore that was not in the metallic state, and 

 forms muriate of silver. 



In this state the ore is subjected to various mechanical opera- 

 tions, with riddles, screens, mills, and sieves, until it is reduced 

 to an impalpable powder. It is then submitted to the action of 

 the mercury, which is the actual process of amalgamation. This 

 is performed in barrels, which are so arranged as to revolve on 

 their axis. The mixture or charge in each barrel consists of 

 sifted calcined ore, mercury, metallic iron, and water, in certain 

 proportions. The ore is composed of sulphate of soda, muriate 

 of silver, muriate of iron, and other metals and earthy matters. 

 By the process of amalgamation, the barrels being made to 

 revolve during a period of 16 or 18 hours, the muriate of silver 

 becomes decomposed by the action of the iron on its acid, and 



