Ores in which the copper is present as oxide or carbonate are soluble in sulphuric or hydrochloric acids, ferrous chloride, ferric sulphate, ammoniacal compounds and sodium thiosulphate.
In the case of iron, ferric sulphate, Fe2(S04) 3, is produced; tin yields a somewhat indefinite sulphate of its oxide Sn02.
It dissolves in acids to form a mixture of a ferrous and ferric salt,' and if an alkali is added to the solution a black precipitate is obtained which dries to a dark brown mass of the composition Fe(OH)2Fe203; this substance is attracted by a magnet, and thus may be separated from the admixed ferric oxide.
LIMONITE, or Brown Iron Ore, a natural ferric hydrate named from the Gr.
It is probably a hydroxy-compound, since it gives a red-brown colour with ferric chloride, reacts with phenyl isocyanate and with phosphorus pentachloride, and with benzoyl chloride yields dibenzhydroxamic acid, C 6 H 5 CO NH O.
By fusing iron with saltpetre and extracting the melt with water, or by adding a solution of ferric nitrate in nitric acid to strong potash, an amethyst or purple-red solution is obtained which contains potassium ferrate.
With ferric chloride it gives a violet coloration, and with bromine water a white precipitate of tribromphenol.
Primarily but a slight deposit is formed (none until the concentration arrives at specific gravity 1.0509), this deposit consisting for the most part of calcium carbonate and ferric oxide.
Titanic oxide separates out as a white hydrate, which, however, is generally contaminated with ferric hydrate and often with tin oxide.
The conversion of copper sulphide into the chlorides may be accomplished by calcining with common salt, or by treating the ores with ferrous chloride and hydrochloric acid or with ferric chloride.