Prop., &c. Solid below 68° Fahr.; above it, a yellowish fuming liquid, which boils at 428° Fahr.
Arsenic, Trichlo′′ride of. AsCl3. Syn. Chlo′′ride of a., Arsen′ici terchlori′dum, &c., L. Prep. 1. From a mixture of white arsenic, 1 part; and bichloride of mercury, 6 parts; both in powder, carefully distilled into a well-cooled receiver.
2. Gently boil powdered white arsenic for some time in hydrochloric acid to which a little nitric acid has been added; then concentrate cautiously by evaporation, and distil as before. It is also produced, with the disengagement of heat and light, when powdered metallic arsenic is thrown into gaseous chlorine.
Prop., &c. A colourless, volatile, highly poisonous liquid, decomposed by water into arsenious acid and hydrochloric acid. It has been employed as a caustic in cancer and venereal warts; but its use requires the greatest caution.
Arsenic, Flu′oride of. AsF3. Syn. Arsenic trifluoride, Terflu′oride of arsenic. A fuming volatile liquid, prepared as the bromide.
Arsenic, Trii′odide of. AsI3. Syn. Teriodide of arsenic, Iodide of arsenic; Arsen′ici iodi′dum, A. teriodi′dum, L.; Arsenic iodure, &c., Fr. Prep. 1. From finely-pulverised metallic arsenic, 2 parts; iodide, 11 parts; mixed and gently heated in a bent glass tube, or a suitable retort, until combination is complete; the heat being then raised, and the sublimed iodide collected, and at once put into a well-stopped phial.
2. Arsenic, in fine powder, 1 part; iodine, 5 parts; triturate them together, place the mixture in a small flask or retort just large enough to contain it, and apply a gentle heat until liquefaction is complete, avoiding the formation of iodine vapour; when the odour of iodine is no longer perceptible, and the mass assumes a reddish-yellow colour and crystallises on the sides of the vessel, the operation is complete, without having recourse to sublimation. A very easy and excellent process.
Prop., &c. A deep orange-red, crystallisable solid; soluble in water, and highly volatile and poisonous. Its aqueous solution yields the iodine unchanged by rapid evaporation, but when slowly concentrated and set aside, white pearly plates are obtained, consisting of arsenious acid and the teriodide. As a medicine it combines the properties of both arsenious acid and iodine, but its use requires great caution. It has been successfully employed by Dr A. T. Thomson, Biett, and others, in obstinate skin diseases (lepra, impetigo, herpes, lupus, psoriasis, &c.), and in real or stimulated cancer.—Dose, 1⁄16 to 1⁄12 gr. (in pills or solution), gradually increased to 1⁄6 or even 1⁄3 gr. (A. T. Thomson.) Externally, 21⁄2 gr., to lard 1 oz.; of which 1 dr. may be used at a time. (Biett.)
Arsenic, Disulphide of. As2S2. Syn. Arsenic bisulphide, Bisul′phide of a., Red sul′phide of a., &c., Realgar; Réalgal, Arsenic rouge sulfure, Orpin rouge, &c., Fr.; Rothes schwefelarsenik, &c., Ger. This substance is found native at Solfaterra, near Naples, and in several other volcanic districts; but that of commerce is often prepared by distilling arsenical pyrites, or a mixture of sulphur and white arsenic, &c., in the proper proportions, as noticed under Reälgar and Red Pigments.
Prop., &c. A fusible, volatile substance; scarlet or ruby-red in mass, but orange-red in powder, by which it is distinguished from cinnabar; crystals, oblique rhombic prisms. Sp. gr. 3·3 to 3·6. Its chief use is as a pigment and in pyrotechny to make white fire. The factitious sulphide has not the rich colour of the native mineral, whilst it is much more poisonous. It is improved by re-sublimation.