THE ARSENIC, apoƐVIKOV, ARSENICUM, in min- eralogy and chemistry, called by Aristotle carepayn, by Theophrastus appevrov, by the Romans orpimentum and arsenicum; is a red- dish-colored ponderous mineral, caustic, cor- rosive, and highly poisonous; which was used by the ancients in medicine and painting. Aristot. de Hist. Anim. 1. 8, c. 24; Theophrast.; Dioscor. 1. 5, c. 121; Plin. 1. 34, c. 18; Cels. de Re Med. 1. 5, c. 5; Gal. de Comp. Med. sec. Loc. 1.4. In the Linnæan system, it is a genus of metals having these generic characters: Bluish The principal species are, 1. A. nativum, na- tive asenic, of the three varieties: a. Uncombined, having a metallic lustre and separating into spherical incrustations. B. With micaceous particles. y. Friable and porous. Found in the British Isles, Norway, Germany, Saxony, &c. in spar, baryte, or feldspar, massive, rarely disse- minated, often composed of hemispheric layers, corroded, branched, perforated, botryoidal, or stalactitic; color lead-gray, but its surface soon tarnishing and becoming black by ex- posure to the air; streak bluish-gray, powder dull and blackish; sometimes a little sonorous when struck against a hard body, and so soft as to be easily cut with a knife. Before the blow-pipe it emits a white smoke, diffusing its peculiar and highly poisonous vapors to a great distance; burning with a blue flame and gradually vanishing, depositing a white oxid in the form of a powder: specific gravity 5-670 to 5-729; always alloyed with some iron, and often contains some cobalt, bismuth, silver, and 2. A. calciforme; white arsenic; white oxid of arsenic; white, soluble in eighty 3. A. auripigmentum; orpiment, yellow arsenic. Ponderous, yellow, curved, or un- dulately foliated, of a waxy internal lustre, evaporating almost entirely before the blow-pipe. Found in Great Britain, Hungary, Georgia, Turkey, &c.; massive, disseminated, or in small imperfect crystals; color, various shades of yellow, with a considerable waxy lustre, and some transparency; streak orange-yellow, not metallic; texture foliated, with the plates mostly curved or undulated, rarely striate, a little flexi- ble, but not elastic; effervesces with hot nitric 4. A. sandaraca; red arsenic; ruby arse- perficial, or crystallised in small acute-angled, quadrangular, or acicular prisms; color auro- ra-red, ruby, scarlet, crimson or blood-red, often variegated with yellow traces: texture lamellar, with the foliations a little flexible, and so soft as to be cut with a knife, and frequently exhibit- ing a brilliant lustre; streak yellowish-red; pow- der scarlet; in nitric acid it loses its color; 5. A. sulphuratum; marcasite; white mundic; white pyrite; pyritical arsenical ore. Hard, bluish-gray with metallic lustre, before the blow-pipe emitting white arsenical vapors and blue sulphureous flames. in various parts of Great Britain, Germany, Sweden, hemia, Saxony, &c. in irregular masses, disseminated, investing or crystallised in cubes or four-sided prisms; specific gravity 6. A. albicans; misspickel; marcasite. Of a steel-white color and lustre, hard, emitting white arsenical vapors before the blow-pipe, but no sulphureous flame or vapor. in Cornwall, near Dublin, in Bohemia, Silesia, B an arsenical smell when rubbed. It consists of arsenic alloyed with a considerable quantity of iron, but little or no sulphur; specific gravity from 5.753 to 6.522. 7. A. argentiferum; argentiferous arsenic. Of a silvery lustre and very fine granular texture, emitting arsenical vapors before the blowpipe, and when fused with lead leaving a silver bead. Found in the mines of Saxony, Bohemia, Germany, and Spain; massive, disseminated, or acicular; color nearly that of the last, but brighter and more permanent; burns with a white flame, and leaves a reddish residuum: by solution in nitro-muriatic acid the silver will be precipitated. It consists of arsenic, sulphur, iron, and from 1 to 10 or 12 per cent. of silver: specific gravity 4.087. The following is the method of the celebrated Mr. Chevenix for the assay and analysis of arsenical ores. Reduce the ore to a very fine powder, and digest it in nitric acid sufficient to acidify and take up the whole of the arsenic; pour off the clear liquor, and boil on the residue some distilled water: filter, and add the water to the nitrous solution: then neutralise the excess of acid by potash, taking care, however, not to have an excess of alkali, and add nitrate of lead as long as any precipitate takes place wash the precipitate in cold water, dry, and weigh it. As the arsenical ores often contain sulphur, it is possible that the arseniat of lead thus procured may be mixed with a little sulphat of lead: to decide this, digest the powder in some warm dilute muriatic acid, and the arseniat of lead will be dissolved, leaving the sulphat behind. The arsenic of commerce is prepared in Saxony by roasting the cobalt ores in the manufacture of zaffre. These ores consist principally of arsenic, cobalt, iron, and a little sulphur; the first and last ingredients are easily separated by roasting, which is performed not in the open air, but in an oven, the flue of which runs horizontally to a considerable distance before it bends upwards. The arsenic and sulphur, when liberated, are deposited for the most part in the horizontal flue. In this state it is called Crude arsenic, or flowers of arsenic, and the form it assumes is that of a grayish meal streaked with yellow, which is occasioned by the sulphur uniting with parts of the arsenic, and composing orpiment. From the crude arsenic the White arsenic of commerce is prepared by mixing the crude with potash or lime, and resubliming. The sulphur and other impurities are thus combined with the alkali, and the white oxide is driven over into a heated receiver, where it melts into a heavy, colorless, transparent glass by exposure to the air for a short time this glass becomes opaque, and resembles in its fracture the finest white china; it is in this state that the white arsenic of commerce is sold in the shops, and kept in our laboratories; and as it is then an oxide of the metal approaching very nearly to a state of purity, it is not difficult, by separating its oxygen, to reduce it into Pure metallic arsenic. For this purpose the white arsenic is mixed with any of the vegetable or animal expressed oils, till it becomes of the consistence of very soft glazier's putty, and round or oblong pieces of the paste are dropped into a Florence flask, or earthen retort, so as not to adhere to the sides. It is then put into a sandbath, or over a gentle charcoal fire, and heated very gradually until it ceases to emit thick vapors, when the heat may be increased by degrees to obscure redness. Shortly after the vessel may be removed, and when cold, broken; the neck and upper part will contain a crystallised oxide of arsenic; below, a thick crust of metallic arsenic; and at the bottom some impurities, which must be laid aside. The other products are to be pulverised with half their weight of charcoal, and sublimed again as before; by which means the arsenic is rendered pure, and will be found to line the vessel in the form of a shining crust and crystals. The principal properties of pure arsenic, beside those mentioned in the beginning of this article, are the following:-That it is not perceptibly soluble in water, and is easily tarnished by exposure to the air; the best method of preserving it unaltered is to immerse it in water or alcohol. With carbon or hydrogen it does not combine; but the latter substance, in the state of gas, dissolves it. Oxygen unites with it by combustion, forming arsenical acid. With sulphur it may be readily united, forming either realgar or orpiment, according to the proportions of the ingredients, or the methods of uniting them: these substances are really sulphurets of arsenic, and their properties, with their mode of preparation, when not found native, may be found under their names. Arsenic combines also readily with phosphorus, forming phosphuret of arsenic, which is black and brilliant; but with azotic gas it has not been united. Muriatic acid attacks arsenic only if aided by heat; but, by distilling equal parts of orpiment and corrosive muriate of mercury (corrosive sublimate) in a gentle heat, a blackish corrosive liquor is obtained, which is the sublimated muriat of arsenic, or butter of arsenic. Arsenic combines with most metals, forming with them alloys, and rendering them more fusible and brittle; though such of them as were before very fusible become refractory: it possesses also the singular property of destroying the magnetic virtue of iron, and of all other metals susceptible of it. The most useful alloys of arsenic are:-1. With platinum, which is formed by fusing that metal and the white oxide of arsenic together. By this means platinum, itself so untractable, may be wrought into the utensils required. The mixture, after fusion, is hammered at a red heat into bars, and the arsenic is gradually driven off. 2. With copper, which is formed by fusing the two metals together in a close crucible, their surface being covered with common salt, to prevent the arsenic from being oxidised by the air. This alloy is white and brittle, and when mixed with a little tin or bismuth is used for a variety of purposes in the arts, when it is known by the names of white copper or white tombac. 3. With iron, which is likewise done by fusion. This alloy, however, is often found native, and is then called misspickel. The other metals with |