SILVER 



807 



addition of quicklime counteracts the injurious effect of too much magistral, by de- 

 composing the resulting sulphate of copper. Quicksilver, when introduced in too great 

 quantities, is apt to cool the mass too much, and thereby enfeebles the operation of 

 the proto-chloride of copper upon the silver. 



Waskoe Amalgamation Process. The system of amalgamation largely carried out in 

 the silver-works at Nevada, was originally introduced in the Washoe district, whence 

 it derives its name. The ores having been broken by Blake's stone-breaker, or by 

 hammers, are fed into a stamping-mill, where they are crashed wet. The stuff dis- 

 charged from the stamps passes to the settling-tanks, in which the finely-suspended 

 ore is allowed to subside. It is then transferred to the amalgamators, which are 

 usually cast-iron pans, of which various forms have been constructed by Varney and 

 Wheeler, Hepburn and Peterson, and other makers. In these pans the ore is ground 

 with hot water and mercury, often with addition of certain 'chemicals,' such as 

 common salt and sulphate of copper. The impure amalgam is discharged from the 

 pan into the separators or settlers, where it is cleansed, and whence it is generally 

 transferred to the agitators. The superfluous mercury having been strained away, the 

 clean amalgam is retorted, the mercury being thus distilled off, whilst the silver 

 remains behind, and after melting is cast into ingots. 



1797 



Barrel Amalgamation. The old amalgamation-works at Halsbriicke, near Freiberg, 

 for the treatment of silver ores by mercury, were much admired, and we will therefore 

 give a sketch of their former arrangement. It should be mentioned, however, that the 

 barrel-amalgamation process has not been worked there since 1856. 



Fig. 1797 presents a vertical section of this great Usine or Huttenwerk, subdivided 

 into four main departments. The first, A, B, is devoted to the preparation and roast- 

 ing of the matters intended for amalgamation. The second, B, c, is occupied with 

 two successive siftings and the milling. The third, c, D, includes the amalgamation 

 apartment above, and the wash-house of the residuums below. And in the fourth, 

 D, E, is placed the distilling apparatus, where the amalgam is finally delivered. 



1 . In division A, B ; a, a, is the magazine of salt ; b, b, is the hall of preparation of 

 the ores ; on the floor of which they are sorted, interstratified, and mixed with salt ; 

 c, c, are the roasting furnaces; in each of which we see, 1, the fireplace; 2, 3, the 

 reverberatory hearth, divided into two portions, one a little higher than the other, 

 and more distant from the fireplace, called the drier ; the materials to be calcined 

 fall into it through a chimney, 6. The other part, 2, of the hearth is the calcining 

 area. Above the furnace are chambers of sublimation, 4, 5, for condensing any vola- 

 tile matters which may escape by the opening 7. e is the main chimney. 



2. In the division B, c, we have d, the floor for the coarse sifting ; beneath, that 

 for the fine sieves ; from which the matters fall into the hopper, whence they pass 

 down to g, the mill-house, in which they are ground to flour, exactly as in a corn- 

 mill, and are afterwards bolted through sieves. p,f, is the wheel-machinery. 



3. The compartment c, D, is the amalgamation-house, properly speaking, where the 

 casks are seen in their places. The washing of the residuums is effected in the shop 

 I, below. &, k, is the compartment of revolving casks. 



4. In the division D, E, the distillation process is carried on. There are four similar 

 furnaces, represented in different states, for the sake of illustration. _ The wooden 

 drawer is seen below, supporting the cast-iron basin, in which the tripod, with its 

 candelabra for bearing the amalgam-saucers, is placed, q is a store chamber. 



At B, are placed the pulleys and windlass for raising the roasted ore, to be sifted 

 and ground ; as also for raising the milled flour, to be transported to the amalgama- 

 tion-casks. At D, the crane stands for raising the iron bells that cover the amalgama- 

 tion candelabra. 



