Page:Proceedings of the Royal Society of London Vol 60.djvu/429

Rh The precipitates of Phosphates and basic acetates D, E, and G. Precipitate E.

Chromium................ 5206 4289'0 4274-0 42530 3606 35940 3579-0 Gallium .................... strong 41716a n d 4032-7 (the latter somewhat weaker). Calcium............ . weak 4226"8 Potassium.................. strong 4047"0 4043"5 Sodium...................... strong 5893-0, faint 5685, and 33030

Precipitate D.

The ehromium lino 5206 did not appear in the spectrum of this precipitate. Both the gallium lines were very distinct, 4171-6 and 4032-7. It is remarkable how very generally the spectrum of potassium appears along with that of the precipitated substances, whether metals or basic acetates.

Precipitate of basic acetates, G. This contained iron, chromium, lead, gallium, potassium, and sodium. The lines -were those which have already been particularised.

The Residue left by Zinc, H .— This was heated with aqua regia, when all but a very small quantity of silica with a trace of a metallic oxide dissolved. The liquid was filtered and the filtrate evaporated with excess of hydrochloric acid to remove nitric acid. It was diluted with water, when it showed a green colour.

It was saturated with sulphuretted hydrogen and filtered to separate the precipitate. The precipitate was partially soluble in sodium hydrogen sulphide, yielding a sherry-coloured solution; the constituent causing this colour was not identified, the quantity present being very small. The residue, insoluble in alkaline sulphide, contained copper and a trace of lead, but no mercury, bismuth, or cadmium.

The filtrate from zinc and precipitated metals I, was diluted and heated to boiling. It gave a precipitate, and therefore ammonium acetate was added to the hot liquid, and after boiling for several minutes it w'as filtered. The filtrate became turbid immediately; it was then boiled and more ammonium acetate added and then filtered ; the filtrate again became turbid.

This precipitate was filtered off and heated in the oxyhydrogen flame.

it contained no gallium, but the spectrum gave lines of iron, copper, sodium, potassium, and a trace of lead.

It is evident that all the gallium was extracted by the repeated additions of ammonium acetate solution and boiling.