Mr Crookes, F.R.S., has, by means of the addition of a certain proportion of sodium, in the form of an amalgam, to the mercury, effectually prevented this serious loss of gold and mercury. By adding certain quantities of amalgams B and C, an amount which, differing from each ore, is ascertained by experiment, the ‘flouring’ and ‘sickening’ of the mercury is effectually prevented, the mercury remaining throughout in the best condition. The addition of about one tenth per-centage of amalgam A, at intervals of some hours, increases most powerfully the affinity of the mercury for the precious metals, and secures a more thorough amalgamation.
This invention has met with general approval, and experiments conducted at many mines show its great practical value, giving an increase of from 5 to 30 per cent. in the yield of gold, and, in fact, with many pyrites that yielded no gold to the ordinary amalgamation process, gave a considerable yield of gold to the sodium amalgamation process. This has led to its use in most mines, both silver and gold, in America.
Gold, Iodide of. AuL3. Syn. Auric iodide, Tri-iodide of gold, Gold teriodide, Auri iodum. Prep. Add a solution of trichloride of gold to one of iodide of potassium. The resulting precipitate is at first redissolved on agitation, a soluble double iodide being formed; subsequently the iodide of gold is precipitated, leaving the supernatant liquor free of colour.
Prop., Uses, &c. A dark-green powder, easily soluble in hydriodic acid. It is occasionally employed as a medicine, and, like other preparations of gold, is of an alterative character.—Dose. About 1⁄16th of a grain.
Gold, Oxides of:—
1. Monoxide. Au2O. Syn. Aurous oxide, Protoxide of gold. Prep. Formed by treating the aurous chloride with strong potassium hydrate. Green powder, somewhat soluble in potassium hydrate solution, and readily decomposing into metallic gold and auric oxide.
2. Trioxide. Au2O3. Syn. Auric oxide, Oxide of gold, Peroxide of gold, Auric acid, Auri oxidum. Prep. Magnesic oxide, 4 parts; auric chloride, 1 part; water, 40 parts; mix, boil, and wash the precipitate with water, dilute nitric acid, and again with water. It must be dried in the shade.
Reddish-yellow powder, easily decomposed by heat; readily soluble in hydrochloric and hydrobromic acids and strong nitric acid, but insoluble in water and the other acids. Forms unstable salts with the alkalies.
Uses, &c. Trioxide of gold has been given in scrofula, &c., in doses of 1⁄12 to 1⁄2 gr., or 1 gr., in scrofula, syphilis, &c., made into a pill with extract of mezereon.
Gold, Ammoni′uret of*. Syn. Aurate of ammonia, Berthollet’s fulminating gold; Aurum ammoniatum, Ammoniæ auras, L. Prep. By adding ammonia to a solution of gold in aqua regia (trichloride), as long as a reddish-yellow precipitate (fulminating gold) forms; the latter must be collected, washed, and dried with the greatest possible caution.