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Hydrocyanic Acid

This is also called prussic acid, and consists of a thin, colorless, and volatile liquid, having a strong odor of peach kernels. It boils at 79° Fahr. and solidifies at 45°; its specific gravity is も ACIDS. .7058. It constitutes one of the most deadly | and convenient. To 100 grains, or any other poisons known. Its salts are HYDROCYAN- convenient quantity of the acid contained in ATES and METALLIC CYANIDES. Prussic acid, a small phial, add in succession, small quaneven when dilute, is very liable to sponta- tities of the peroxide of mercury in fine neous decomposition, and this speedily occurs powder, till it ceases to be dissolved on agitawhen it is exposed to the light. To promote tion. The weight of the red precipitate taken its preservation, it is usual to surround the up being divided by 4, gives a quotient reprebottles containing it with thick purple paper, senting the quantity of real prussic acid and to keep them inverted in an obscure sit- present. By weighing out beforehand, on a uation. The addition of a very small quan- piece of paper or a watch-glass, 40 or 50 grains, tity of muriatic acid renders it much less of the peroxide, the residual weight of it liable to change, and is generally made by shows at once the quantity expended. The manufacturers for that purpose. operation may be always completed in five

3948. To Obtain Anhydrous Prussic minutes, for the red precipitate dissolves as Acid. Pure crystallized ferrocyanide of po- rapidly in the dilute prussic acid, with the aid tassium, 15 parts; water and sulphuric acid, of slight agitation, as sugar dissolves in waof each 9 parts; distill in a glass retort into a ter. Should the presence of muriatic acid be well-cooled receiver, containing chloride of suspected, then the difference in the volatility calcium in coarse fragments, 5 parts; stop of prussiate and muriate of ammonia may be the process as soon as the chloride in the re- had recourse to with advantage; the former ceiver is perfectly covered by the distilled fluid, and decant the acid into a bottle furnished with a good stopper. Keep it in the dark, with the bottle inverted.