Page:Proceedings of the Royal Society of London Vol 2.djvu/96

Rh Edmund Davy proceeds to detail the processes by which he succeeded in procuring it.

A solution of leaf platinum in nitro-muriatic acid was evaporated to dryness, re-dissolved in water, and precipitated by sulphuretted hydrogen. This hydro-sulphuret was converted into a sulphate by the action of nitrous acid. Ammonia, in slight excess, was added to the solution of this sulphate, and the precipitate so obtained boiled in a solution of pure potash. It was then collected on a filter, washed, and dried at 212°. This powder is of a brown colour, explodes with a loud report when heated to about 400°, and lacerates the substance in contact with it, in the same way as fulminating gold. At a temperature of 300° it is decomposed without explosion when in contact with mercury. It explodes by friction, but not by percussion. It is tasteless; insoluble in water, soluble in sulphuric, nitric, and muriatic acids. When heated in chlorine, muriate of ammonia and muriate of platinum are produced. When heated in ammonia and in muriatic acid gas, it is decomposed; and in the latter, with nearly the same phenomena as in chlorine. Heated with sulphur, it affords sulphuret of platinum.

From the method pursued in obtaining this compound, the author inferred its resemblance to fulminating gold; and on heating it in close vessels, obtained water, nitrogen, and platinum, as the results of its decomposition. Heated with common quick-lime, it afforded liquid ammonia and a little nitrogen.

Mr. Edmund Davy next proceeds to a detail of experiments made in order to ascertain the relative proportions of the component parts of this new fulminating platinum.

In these experiments, 10 grains of the powder furnished 7·3 grains of metallic platinum.

In a fourth experiment, nitrous acid was boiled to dryness upon 10 grains of the powder. The dry mass heated red-hot, furnished 8·25 grains of a gray shining substance, which is a hitherto undescribed oxide of platinum, consisting of 88·3 platinum +11·7 oxygen. From the quantity of nitrogen yielded during the decomposition of the fulminating platinum, and from other experiments, Mr. Davy estimates the quantity of ammonia that it contains, at 9 per cent, and gives as its component parts,

This paper concludes with some general and theoretical observations respecting the formation and decomposition of the new fulminating compound. When the triple sulphate of platinum and ammonia is boiled in a solution of potash, the sulphuric acid unites to the potash, a portion of the ammonia is evolved, and the remainder,