With concentrated ammonia auric oxide forms a black, highly explosive compound of the composition AuN2H3.3H20, named " fulminating gold "; this substance is generally considered to be Au(NH 2)NH.
Auric sulphide, Au 2 S 31 is an amorphous powder formed when lithium aurichloride is treated with dry sulphuretted hydrogen at - 10°.
They are soluble in water and give characteristic precipitates with platinic and auric chlorides, and with potassium ferrocyanide.
When a concentrated solution of auric chloride is treated with caustic potash, a brown precipitate of auric hydrate, Au(OH) 3, is obtained, which, on heating, loses water to form auryl hydrate, AuO(OH), and auric oxide, Au 2 0 3.
Aurous chloride, AuCl, is obtained as a lemon-yellow, amorphous powder, insoluble in water, by heating auric chloride to 185°.