Page:The New International Encyclopædia 1st ed. v. 02.djvu/95

ARSENIC. as speculum metal in bronzing brass, and in the manufacture of opal glass: also for hardening lead in the manufacture of shot. Arsenic and its soluble compounds are exceedingly poisonous.

Arsenic forms two oxides — the arsenic tri- oxide and the arsenic pentoxide. The former yields with basic radicals the salts called ar- senites. It is commonly called white arsenic, arsenious acid, or flowers of arsenic, and is ob- tained in various metallurgical processes by roasting arsenic ores, during which the vapors of the oxide are volatilized and subsequently condensed in receptacles called poison chambers, or poison towers. The crude oxide is purified by one or more sublimations, yielding ultimately a white crystalline powder that is odorless, but has a weak, metallic, sweetish taste. It is the principal commercial compound of arsenic, and is used for the preparation of other arsenical compounds, in the production of green pig- ments, in the manufacture of glass, and as a poison for rats and vermin; also in medicine, in various compounds such as Fowler's solution, which is an arsenite of potassium. Arsenious oxide is used in medicine in treating many skin diseases, in aniemia. in chorea, in some forms of malarial fever, in cancer and other malignant growths, in neuralgia, in asthma, and in certain gastric conditions. It is an alterative, and is frefiuently used in connection with other tissue- builders or tonics during convalescence. Since small quantities produce poisoning, arsenic should be used only when prescribed by a physi- cian. Chronic poisoning by this metal is not infrequent as it is much used in the arts, re- sulting in kidney disease and even paralysis. Yet it is asserted that in Styria the peasants consume arsenic daily — the women to improve their complexions, the men to increase their power of endurance. They are said to be strong and long-lived (see Edinburgh Medical and Surgical Journal. 1871, Vol. XVI., p. 569). Freshly precipitated hydrated oxide of iron, and the freshly precipitated hydrated oxide of iron with magnesia, are regarded as the best and most efficient antidotes for arsenious acid; but immediate removal of the poison by vomiting or purging is desirable. For its detection, three methods are commonly employed. Of these, the first consists in the treatment of the material submitted for examination with a strong alkali, and passing through the filtered liquid a current of hydrogen disulphide, which, if arsenic be present, produces a precipitate of the yellow sulphide. The precipitate may be further tested by dissolving in ammonia and evaporating until the residuary substance is reduced to metallic arsenic. Another method is the Reinsch pro- cess, in which, the preparation containing arsenic having been brought into solution, newly bur- nished pieces of copper foil are introduced into the liquid, and if arsenic be present it will at once be precipitated on the copper in its metallic form. It is said that by this method one part of arsenic can be detected in 250,000 parts of solution. A third, and perhaps the most useful, method is that invented by Marsh, which consists in treating the material with dilute sulphuric acid and metallic zinc in a gas-generating apparatus. The arsenic combines with the hydrogen liberated by the zinc, and forms arseniuretted hydrogen, which is then passed through a glass tube; on heating, it

breaks up, depositing metallic arsenic in the form of a 'mirror' near the open end of the tube. In carrying out this operation, especially in criminal cases, the utmost precautions are neces- sary to insure the perfect freedom of the ap- paratus and reagents used from arsenic or simi- lar substances capable of producing an arsenic- like 'mirror.' Among other things, the nature of the mirror may be demonstrated by dissolv- ing it and testing the solution obtained by one of the usual methods. In order to detect arsenic in wallpapers or cotton fabrics, the Marsh test is usually employed — that is, the material is brought into solution, to which zinc and sul- phuric acid are added, yielding the arseniuretted hydrogen. It frequently happens that the ar- senic is contained in the fabric itself, so that the test must not be made with the dissolved color alone, but with the entire material. With cop- per oxide arsenious oxide forms a copper arsen- ite which is a pigment known as Scheele's green, largely used in calico printing and for wall-papers. With basic copper acetate it yields Schweinfurth green—called also emerald green, imperial green, and mitis green—which is a well-known pigment frequently used in the manufacture of wall-paper.

When acted upon by oxidizing agents, arsenious oxide yields arsenic oxide, which combines with basic radicals to form arsenates. Arsenic oxide, or arsenic acid, is used as an oxidizing agent in the preparation of aniline red, and also as a substitute for tartaric acid in calico printing.

Arsenic combines with sulphur, yielding an orange-yellow disulphide, which is found native as the mineral realgar and is used as a pigment and as a depilatory. A trisulphide also exists, which is found native as the mineral orpiment, which is used in pyrotechny and as a pigment for artists; also formerly in dyeing, and with quick-lime as a depilatory under the name of rusma.

ARSE'NIOUS ACID. See.

ARSENOPY'RITE (From arsenic + pyrite), or An iron sulpharsenide that crystallizes in the orthorhombic system, has a metallic lustre, and is silver-white in color. It occurs associated with various ores of gold, lead, silver, and tin, in igneous crystalline rocks, and has considerable value as an ore of arsenic (q.v.).

ARSIN'OË (Gk. Ἀρσινόη). A Greek feminine name which was especially popular in the Macedonian dynasty of Egypt, the family of the Ptolemies. The wife of Lagus and the mother of Ptolemy I, was named Arsinoë. Other noteworthy princesses who bore the name were: (1) born about B.C. 316, the daughter of Ptolemy I. and Berenice. She was married in her sixteenth year to the aged Lysimachus, King of Thrace. The eldest son of this king, Agathocles, had previously married Lysandra, Arsinoë's half-sister. Arsinoë's brother, Ptolemy II. Philadelphus, afterwards wedded Arsinoë I., the daughter of Lysimachus. Arsinoë II., wishing to secure the throne for her children, prevailed on her husband to put Agathocles to death. Lysandra, however, fled with her own children to Seleueus of Syria, and induced him to declare war against her father-in-law, who lost his life and kingdom. Arsinoë II. sought