ARSENIC, as it is to be found in the shops, occurs in the state of a white ox ide, from which the metal may be obtain ed by the following process. Mix two parts of the white oxide with one part of black flux (prepared by detonating in a crucible one part of nitre with two of crystals of tartar), and put the mixture into a crucible. Invert over this another crucible ; lute the two together, by a mix ture of clay and sand, and apply a red heat to the lower one. The arsenic will be reduced, and will be found lining the inside of the tipper crucible, in a state of metallic brilliancy. Arsenic is oxidized by mere exposure to the atmosphere. It soon becomes tarnished, loses its metal lic lustre, and is changed into a blackish oxide. It is readily fusible, and is vola tilized at 356°. In close vessels it may be collected unchanged; but when thrown on a red hot iron, it burns with a blue flame and a white smoke, and a strong smell of garlic is perceived. All the mi neral acids act on arsenic ; but not consi derably, unless they are heated. In the oxigenized muriatic acid gas, however, arsenic burns vehemently. A mixture of oxymuriate of p otash and arsenic fu rnishes a detonating compound, which takes fire with the rapidity of lightning. The salt and metal, first separately powdered, may be mixed by the gentlest possible triture, or rather by stirring them together on pa per with a knife point. If two long trains be laid on a table, the one of gunpowder, and the other of this mixture, and they be in contact with each other at one end, so that they may be fired at once, the arseni cal mixture burns with the rapidity of lightning, while the other burns with com paratively extreme slowness. Arsenic has the property of giving a white stain to copper. Let a small bit of metallic ar senic be put between two small plates of copper ; bind these closely together with iron wire, and heat them barely to red ness in the fire. The inside of the cop per plates will be stained white. The white oxide of arsenic has the following properties : 1. It has an acrd taste, and
is highly poisonous. 2. It is soluble in water, which, at the ordinary temperature, takes up 1-80th. According to La Grange, it is soluble in 1-24th of cold water, or 1-15th of hot. 3. Oxide of arsenic com bines with the pure alkalies to saturation ; and hence it fulfils one of the principal functions of an acid. It has therefore been called arsenous acid, and its com pounds arsenites. They may be formed by simply boiling the acid with a pure al kaline solution. 4. The arsenous acid, by distillation with sulphur, affords either a yellow substance, called orpiment, or a red one, termed realgar. Both these coin pounds are sulphuretted oxides of arsenic, varying in the proportion of their com ponents. The hydro-sulphurets also throw down a yellow precipitate from so lutions of arsenous acid. Sulphate of copper, mixed with arsenite of potash, gives a beautiful precipitate, called, from its discoverer, Scheele's green. 5. By repeated distillation with nitric acid, ar senous acid is changed into arsenic acid. The same change is effected also by ex posure to the vapour of oxigenized mu riatic acid, and the expulsion, by heat, of the common muriatic acid. By both these processes, a white concrete sub stance is obtained, termed arsenic acid. The arsenic acid has a sour, and at the same time a metallic taste. It reddens vegetable blues, attracts humidity from the atmosphere, and effervesces strong ly with solutions of alkaline carbonates. With alkalies, earths, and oxides, it con stitutes a class of salts called arsenates. The arsenate of potash may be obtained in a more simple manner, by detonating, in a crucible, a mixture of nitrate of pot ash with arsenous acid. When tin is dis solved in arsenous acid, an inflammable gas is disengaged, as was observed by Scheele, consisting of hydrogen gas hold ing arsenic in solution. It may be obtain ed also by adding powdered metallic ar senic to a mixture of diluted sulphuric acid and zinc filings.
Ansextc acid.
AasEntors acid. See Anse :sic.