Dental metallurgy; a manual for students and dentists.

  • Arthur Bower Griffiths
Date:
1903
Catalogue details

Licence: In copyright

Credit: Dental metallurgy; a manual for students and dentists. Source: Wellcome Collection.

    118/264 (page 98)
    CHArTEK XII SILVER Symbol, Ag; Atomic weight, 107'93 Occurrence.-—^The chief natural forms are metallic silver, silver glance (AggS), stephanite (5AgS, Sb2S3), stromeyerite (AggS, CugS), and horn silver (AgCl). Silver is also present in galena. Preparations.—The principal methods employed for the > I e.Ktraction of silver from its orns are the following :— j 1. By amalgamation. 2. By wet processes. 3. By desilverizing lead, and cupellation. 1. Amalgamation Processes.—Several methods have been described, depending on the action of mercury on compounds of silver, whereby the silver becomes amalgamated, the mercury being separated by distillation. The retorted silver is melted and cast into ingots. Some ores are pre\’iously roasted with common salt and crude copper sulphate before being treated with mercury (Mexican or Patio process). 2. Wet Processes.—(a) The ore is roasted with common salt, the silver being converted into a chloride. The silver chloride is dissolved in a solution of sodium chloride or sodium thiosulphate (“ hyposulphite ”). The silver is then precipitated by placing sheets of copper in the solution, or by the electric current. Tlie spongy silver so formed is finally melted and cast into bars. The above method was