Page:Proceedings of the Royal Society of London Vol 60.djvu/436

404 gallium, &c., precipitated, after reducing the iron to the ferrous state. First •precipitate, U. The second contained some gallium; the third, very dark in colour, was free from that metal.

The precipitates P, R, and U were dissolved in hydrochloric acid, and the solutions filtered to remove a small quantity of insoluble matter which was added to residue M. Two drops of violet-coloured filtrate were tested with potassium ferrocyanide, and so marked was the reaction that it was decided to repeat the process of reduction and precipitation lo remove as mucb iron as possible. The first W contained nearly all the gallium; the second contained a small quantity, and the third contained none.

The first and second precipitations U, whose spectra are seen in 1341 and 1343, contain a small quantity of gallium. They were redissolved, reduced, and boiled with excess of ammonium acetate, and the precipitate collected. A second precipitate was free from gallium. The former was fused with caustic soda, extracted with water and filtered. The filtjrate was acidified with hydrochloric acid, and boiled with ammonia for some time, and the galliam phosphate thus precipitated was collected. This precipitate was added to W.

Residue W, 8fc.—This contained principally gallium and chromium phosphate with some iron phosphate. It was dissolved in hydrochloric acid, and the solution made to contain about one-fourth its volume of strong hydrochloric acid. Potassium ferrocyanide was added, but not an excess, and the bulky, precipitate collected. An excess of the reagent was added to the filtrate, which, after standing twenty-four hours, was filtered. Very small quantities of the two precipitates were examined spectrographically; the second is decidedly richer in gallium than the first.

Residues M and M2 with the small Residues added to them as described.—Ignited at a red heat to burn combustible matter. The mass became grey and weighed, when cold, 8 grams. It was very bulky, and consisted largely of silica. Fusion with fusion mixtures converted the silica into alkaline silicates, which were removed by solution in water, leaving a black residue. This was fused with caustic soda and sufficient nitre to oxidise the graphite, &e. Water dissolved all of this, excepting a small quantity of red oxide of iron, part of which was examined for gallium. None present.

The filtrate was acidified with hydrochloric acid, evaporated to dryness, and dried at 120° C. to dehydrate silicic acid.

The dry residue was digested with strong hydrochloric acid, and water added. It was then filtered to remove some silica, which was found to have retained only a trace of gallium.

The filtrate was mixed with a small excess of ammonia, and boiled fqr some time; the gallium being precipitated probably as phosphate. The filtrate in this and in all similar cases was again boiled, after