Page:Proceedings of the Royal Society of London Vol 1.djvu/38

Rh Vince. The depression of the horizon, frequently noticed hy persons residing near the sea, and some other phaenomena of a similar nature, he thinks may likewise be ascribed to that single cause.

We learn from the introduction to this paper, that mercury, and most, if not all, its oxides, may, by treatment with nitric acid and alcohol, be converted into a crystallized compound, possessing all the inﬂammable properties of gunpowder, as well as many others peculiar to itself. After stating the gradual steps by which he arrived at this discovery, Mr. Howard describes the following process and manipulations, which he found best calculated for producing this powder.

One hundred grains, or a greater proportional quantity, of quicksilver, are to be dissolved with heat in a measured ounce and a half of nitric acid. This solution being poured cold upon two measured ounces of alcohol, a moderate heat is to be applied, until an effervescence is excited. A white fume then begins to undulate on the surface of the liquor, and the powder will be gradually precipitated upon the cessation of action and re-action. This precipitate is to be immediately collected on a ﬁlter, well washed with distilled water, and carefully dried in a heat not much exceeding that of a water-bath. This immediate edulcoration of the powder is material, it being liable to the re—action of the nitric acid, which, while any of that acid adheres to it, renders it subject to the inﬂuence of light. The quantity of the powder produced varies according to the nature of the ingredients; 100 grains of quicksilver yielding from 120 to 132 grains of the compound.

The principal agents which decompose this mercurial powder are the nitric, the sulphuric, and the muriatic acids. The most remarkable effect is that of the sulphuric acid. which, when much concentrated, produces an explosion nearly at the instant of contact, on account, it is thought, of the sudden and copious disengagement of the caloric. When the acid is less concentrated, no explosion takes place; but a considerable discharge of gas, as well as caloric, is nevertheless effected; the former appearing to be a compound of carbonic acid and a peculiar inﬂammable gas, amounting; in the whole to between 28 and 31 cubical inches. The inﬂammable gas was upon close examination found to he a nitrous aetherized gas, which appears to have been not the result of the decomposition, but, in fact, a constituent part of the powder.

Upon the whole of the investigation, Mr. Howard concludes that this mercurial powder is composed of nitrous :etherized gas, and of oxalate of mercury with excess of oxygen. Having stated his reasons for maintaining this opinion, he goes on to explain the theory of the combustion of the mercurial powder, on certain principles previously laid down in the investigation. The hydrogen, he says, of the oxalic acid and of the aetherized gas is ﬁrst united to the oxygen of the