Page:Proceedings of the Royal Society of London Vol 60.djvu/430

398 The various precipitates of basic acetates were mixed, with the exception of that from J, which contained no gallium. In order to separate phosphoric acid, the precipitates were fused with about three times their weight of mixed carbonates. Some potassium nitrate was added towards the end of the fusion, to convert chromium into chromates. The heavy metals were left as oxides or carbonates, the phosphoric acid going into solution. After extraction with hot water, the solution was filtered. Filtrate L. Coloured greenish by manganates, boiled with a few drops of alcohol to separate manganese as hydroxide. Solution, after again filtering from manganese, was yellow from chromates. Residue M. Dried and fused in a silver dish with caustic soda to dissolve gallium hydroxide. Extracted with water and filtered. Residue not examined further. Solution : acidified with HC1 and ammonium chloride and ammonia added. The precipitate was filtered off, dissolved in HC1, and sparked to observe its spectrum. These gallium spectra showed that there were still traces of chromium in the gallium chloride, and from this the gallium was purified completely by precipitation in a strongly acid solution with potassium ferrocyanide and subsequent removal of the iron by treatment with sodium hydrate, according to the method of Lecocq de JBoisbaudran.*

The foregoing description of the analytical details proves the presence of gallium in the metal, and gives a clear indication of how it may be separated by a simple process.

In subsequent operations on the blast-furnace metal, the ferrous' chloride was mixed with calcium carbonate, and the gallium was found to be all precipitated and capable of easy separation from the calcium salt.f Latterly it was found to be more convenient to boil the acid solution containing gallium with an excess of the iron under examination, and thus the gallium is concentrated in the residue which remains undissolved. J

It became necessary to consider what was the source of the gallium contained in the iron. Was the gallium concentrated in the metal P Or did it pass into the slag of the converter? Was it originally contained in the ore, the lime, or the fuel ? Was it easily volatilised, so as to pass off with fume or with flue dust ?

f Loc. d t., p. 1629. J ‘ Comptes Rendus,’ vol. 49, p. 1625.
 * ‘ Comptes Rendus,’ vol. 94, p. 1228.