I i, i Oavev H (+ lx' 1 3) aurous 6py?7 Tor) Beou cis TPkOS.
Aurous oxide, Au 2 0, is obtained by cautiously adding potash to a solution of aurous bromide, or by boiling mixed solutions of auric chloride and mercurous nitrate.
When freshly prepared it dissolves in cold water to form an indigocoloured solution with a brownish fluorescence of colloidal aurous oxide; it is insoluble in hot water.
Aurous chloride, AuCl, is obtained as a lemon-yellow, amorphous powder, insoluble in water, by heating auric chloride to 185°.
Gold dichloride, probably Au 2 C1 4, =Au.AuC1 4, aurous chloraurate, is said to be obtained as a dark-red mass by heating finely divided gold to 140°- 170° in chlorine.
Aurous bromide, AuBr, is a yellowish-green powder obtained by heating the tribromide to 140°; auric bromide, AuBr 3, forms reddish-black or scarlet-red leafy crystals, which dissolve in water to form a reddishbrown solution,and combines with bromides to form bromaurates corresponding to the chloraurates.
Aurous iodide, Aul, is a light-yellow, sparingly soluble powder obtained, together with free iodine, by adding potassium iodide to auric chloride; auric iodide, Au13, is formed as a dark-green powder at the same time, but it readily decomposes to aurous iodide and iodine.
Aurous iodide is also obtained as a green solid by acting upon gold with iodine.
Aurous cyanide, AuCN, forms yellow, microscopic, hexagonal tables, insoluble in water, and is obtained by the addition of hydrochloric acid to a solution of potassium aurocyanide, KAu(CN)2.
Aurous sulphide, Au 2 S, is a brownishblack powder formed by passing sulphuretted hydrogen into a solution of potassium aurocyanide and then acidifying.