Page:Proceedings of the Royal Society of London Vol 1.djvu/198

Rh in general, is left, than the orig'nal weight of the platina; and ad- mits that even a diminution of weight may be sometimes observed. Before the precipitate has been exposed to heat, it may be dissolved in nitro—muriatic acid more easily than platina itself.

The second experiment is to show that when'a mixed solution of platina and mercury is precipitated by metallic iron, a precipitate nearly equal to the sum of the two former metals is generally ob- taiued, the properties of which appear to be similar to those of the precipitate obtained in the ﬁrst experiment.

We learn, from the third experiment, that when an amalgam of platina, formed by means of the ammoniacal muriate of that metal, according to the method of Count Mussin Pushkin, is exposed to heat, a metallic powder remains, which is soluble in nitro-muriatic acid, and affords a copious precipitate by means of green sulphate of iron.

The fourth experiment states, that if sulphur is added to the in- gredients used in the formation of the above-mentioned amalgam, and the whole treated as before, the precipitate caused by green sul- phate of iron is more considerable.

The ﬁfth experiment informs us, that if sulphur is rubbed with ammoniacal muriate of platina, the mixture may be melted on a sand bath. If mercury is then added to the melted mass, and the whole exposed to a strong ﬁre, a button remains, which, being dissolved in uitro-muriatic acid, gives a precipitate, as before, with the green sulphate of iron.

In the sixth experiment we are told, that if sulphuretted hydrogen is passed through a mixed solution of platina and mercury, and the precipitate afterwards melted with borax, the button will not contain any sulphur. Green sulphate of iron causes a precipitate in the so- lution of this button.

The seventh experiment serves to show that phosphate of am- monia, when added to a solution of platina and mercury, causes a precipitate, the solution of which is acted upon by green sulphate of iron.

By the eighth experiment it appears, that if the precipitate formed by adding nitrate of mercury, at the minimum of oxidizement, to muriate of platina be washed, reduced, and afterwards dissolved in nitro-muriatic acid, another precipitate may be produced by means of green sulphate of iron.

The ninth experiment relates to the action of recent muriate of tin, which Mr. Chenevix says is one of the most delicate tests in chemistry, detecting the presence of mercury. If a single drop of neutralized nitrate or muriate of mercury is put into 500 grains of water, the addition of muriate of ﬁn causes the liquor to become turbid, and to assume a smoke-gray colour. And even if the above liquor is diluted with ten times its weight of water, the effect is still sensible. But if recent muriate of tin is poured into a solution, not too much concentrated, of platina and mercury, it can hardly be di- stinguished from a simple solution of platina. If, however, too much