Cheap Solvent of Gold.

Cromwell Argus, Volume III, Issue 143, 6 August 1872, Page 7

Cheap Solvent of Gold.

It is well known that there is no single acid which will dissolve gold, but this metal is readily soluble in a mixture in the proper proportions of nitric and muriatic acids. This mixture has long been known as aqua icgia, royal water. It is composed of one pait nitric acid of 32° Beaume—l.2B specific gravity, and four parts hydrochloric acid 22 Beaume —1.178 specific gravity. As the idea has been advanced of employing this liquid for extracting gold from quartz, in place of the usual process of amalgamating with mercury, Professor Seeley, without endorsing the plan, suggests that, if any miners or mining companies wish to try it, aqua regia might be more cheaply prepared by using certain salts, containing one of the acids, than by employing both of the acids in their pure form. One of these plans is to mix together a solution of common salt—chloride of sodium —in water and nitric acid. Under the action of the nitric acid both the salt and the water become decomposed ; the sodium of the salt combines with the oxygen of the water, forming soda and setting free the hydrogen, w Inch combines with the chlorine of the salt, forming hydrochloric acid. Tims we have hydrochloric acid, and the nitric acid must be in proper proportion to form with it aqua regia. Another plan is to mix together saltpetre, nitrate of potash, and hydrochloric acid. A portion of the hydrochloric acid operates to decompose the saltpetre, setting free its nitric acid to form aqua regia. Still a third method is to mix together salt and saltpetre, sulphuric acid also being present. The sulphuric acid decomposes both the salt and saltpetre, setting free nitric acid, and forming hydrochloric. Gold may be precipitated from a solution in aqua regia by sulphate of iron. Gold may be purified from silver by quatation ; that is, fusing it with three times its weight of silver, and then acting on the mass with nitric acid ; the gold is left as a dark ponder, and may be fused after being washed.