arsenic, arsenick, arsenicke, arsnek

[In Sw. & Ger. arsenik; Fr. & Prov. arsenic, Sp., Port., & Ital. arsenico, Lat. arsenicum, arrhenicum, which, however, is not native arsenic, but sulphuret of arsenic, orpiment; Gr. ἀρσενικόν (arse nikon), άρρενικόν (arrhenikon), not arsenic, but orpiment; ἀρρενικός ( αrrhenikos ) = masculine; ἄρρην (arrhen), older form ἄρσην ( arsen ) = male. From some one of these comes Arab. zirArsenic is so called nakon; Syr. zarnika. from its powerful effects.] A. Ordinary Language: The substance described under B. 1 ( Chem.). "Arsnek, sal armoniak, and brims to on." B. Technically : Chaucer: C. Т. , 12,726. 1. Chem . Arsenic is a triad semi-metallic element, but it may be a pentad in some of its compounds. Symbol, As; atomic weight, 75; vapour density, 150 (H=1); atomic volume,; sp. gr., 575. It volatilises when heated without fusing, and its vapour smells like garlic. It is obtained by distilling native alloys of arsenic and iron, copper, cobalt, or nickel; also by heating arsenious oxide (As2O3) with charcoal in earthen crucibles. Arsenic has a steel-grey metallic lustre, is very brittle, and crystallises in rhombohedrons. It unites with metals when fused with them, forming brittle alloys called arsenides . Arsenic is added to lead used for making shot, to make it run into regular globules. Metallic arsenic is often called black arsenic , to distinguish it from the white arsenic of shops, which is arsenious oxide. Arsenic forms two oxides, arsenious oxide (As2O3) and arsenic oxide (Asg05), but only one chloride, AsCl3 (arsenious chloride). It is prepared by distilling one part of metallic arsenic with six parts of corrosive sublimate or arsenious oxide with strong hydrochloric acid. It is a colourle , oily, poisonous liquid. Arsenic unites with nascent hydrogen, for in ing hydride of arsenic, ASS3. Arsenic forms sulphides (q.v.). It also forms organic bases (see CACODYL and ARSINE). Arsenic is easily detected in cases of poisoning, but the reagents must be first tested for arsenic, as traces occur in zinc and in mineral acids. Compounds of arsenic, when heated on charcoal, give off fumes of metallic arsenic, recognised by its garlic-like smell. If heated with charcoal in a test-tube it forins a metallic ring. Arsenic is precipitated from solutions in the presence of hydrochloric acid by H2S (see ANALYSIS), as a yellow sulphide, As2S3, soluble in sulphide of ammonium, also in carbonate of ammonium. A piece of bright copper heated in a solution containing arsenious oxide or an arsenite rendered acid by hydrochloric acid, becomes covered with a grey film of metallic arsenic. Any arsenic compound treated with zinc and hydrochloric acid gives off arseniuretted hydrogen (AsH3), which burns with a grey-blue flame, and deposits metallic arsenic on a cold porcelain dish held in the flame. It may be distinguished from antimony by di olving in hypochlorite of sodium. Metallic arsenic, heated in a current of air, yields the characteristic octohedral crystals of arsenious acid. Nitrate of silver gives a yellow precipitate with arsenites, and a brick-red one with arseníates. Arseniates require to be reduced, or heated, before they are precipitated by sulphuretted hydrogen. Arseniates give a white crystalline precipitate with magnesium mixture and ammonia like the phosphates. 2. Min . Arsenic occurs native in rhombohedral crystals, or ma ive, reticulated, reniform, and stalactitic. The hardne is 3.5; the sp. gr., 5.93; the lustre, sub-metallic; the colour and streak, tin-white, soon tarnishing dark grey. It occurs with various metals in crystalline and schistose rocks. It is found in Norway, Hungary, Silesia, and the United States. [For other ores of it see REALGAR, ORPIMENT, .] White arsenic is the same as Arseno lite (q. v.). arsenic-glance. In Mineralogy, a variety of Arsenic. arsenic oxide. In Mineralogy, the same as Arseno lite (q. v.). arsenic sulphides. Chem. There are three sulphides-AS2S2, As2S3, and A32S5. Disulphide of arsenic (As2S2) occurs native as realgar (q.v.). It can be prepared by melting metallic arsenic with sulphur. It is used to prepare Indian white fire, a mixture of twenty-four parts of nitre, seven parts of sulphur, and two parts of realgar. Heated with strong sulphuric acid, As2S2 forms arsenious and sulphurous acids. It is used as a pigment. Arsenious sulphide (As2S3) occurs native as orpiment. It is obtained in a pure state by pa ing hydrosulphuric acid (H2S) through a solution of an arsenite acidified by hydrochloric acid. Arsenious sulle is used as a pigment, called King's Yellow, also as a dye stuff. Arsenic sulphide (As S5) does not exist in a separate state, but in combination with metallic sulphides, as sulph arsenates.