PRECIOUS METALS '.'. 



to the vertical revolving shaft and dragged around on the copper 

 bottom by motive power. It was the tendency of the amalgam 

 in this process to adhere to the copper plates which first gave the 

 idea of the introduction of silver plated amalgamated copper 

 plates in the gold milling industry. 



Perhaps the pan amalgamation process is the direct outcome of 

 the cazo and fondon processes with the improved machinery as 

 introduced by Frazer and Chalmers of Chicago. The process is 

 continuous, and the ore is roasted before the effective amalgama- 

 tion takes place, that is, amalgamation takes place far more 

 readily and completely in the presence of roasted ore. 



Smelting Process. This refers to that method of treatment 

 carried out largely in North America and in Germany, where the 

 object is to obtain a solution of silver in lead. The smelting is 

 carried on in the blast furnace of moderate size with a mixture of 

 ore, fuel, and fluxing material. The smelting of silver ore with 

 lead is most satisfactory under the following conditions: (1) 

 Where there is an abundance of bituminous coal or natural gas 

 to serve as a supply of fuel; (2) where limestone, low in magne- 

 sium, is available; and (3) where large quantities of silver-bearing 

 galenite abound. The process is not applicable to cupriferous ores 

 and ores free from lead or poor in silver. The process admits of 

 a continuous discharge of lead through a siphon into some bowl or 

 vat, while the slag is run continuously into iron kettles mounted 

 on tracks so that the cone-shaped slags may be easily transported 

 to the waste yards. Later the slags are run into troughs in which 

 there flows a strong current of water. As the slag strikes the 

 water it is immediately granulated. It is used for certain indus- 

 tries, as in the manufacture of cement. The lead can be ladled 

 from the bowl, or tapped from it, or allowed to run continuously'. 



The Pattinson process depends upon the fact that the alloy of 

 silver and lead can be fused easily and the silver crystallized 

 from the lead. Silver does not form an alloy with lead to 

 any considerable extent as the solution cools. Silver dissolves 

 rapidly in lead at the temperature of fusion of the white metal. 

 In the Pattinson process, when the metal is molten and allowed to 

 cool the lead is ladled out of a large iron pot into kettles upon one 

 side growing richer and richer in silver, and upon the other side 

 poorer and poorer in silver. The material first to crystalize 

 would be pure lead. The material last to solidify is the silver, 

 and between the two, varying amounts of silver and lead are 





