The influence of certain factors and impurities on the precipitation of gold from cyanide solution by zinc dust.

The cyanide process as actually applied to the extraction of gold and silver from their ores is generally considered to have originated with British Patent nos. 14,174, Oct. 19, 1887, and 10,223, July 14, 1888, issued to J. S. MacAuthur, R. W. Forrest and W. Forrest. The first patent emphasized the efficiency of cyanide as a solvent for gold and silver, and the superiority of dilute solutions. The dissolved gold was to be recovered from the solution by any convenient way, "such as evaporating the solution to dryness and fusing the resulting saline residue, or by treating the solution with a sodium amalgam" (30). [...