. Elements of modern chemistry . ts density isabout Arsenic volatilizes without melting at a temperature belowdull redness. Its vapor is colorless. When it is heated understrong pressure it melts to a transparent liquid. On exposureto the air it loses its lustre and assumes a black-gray color ; inthis case its surface becomes covered with a thin layer of abrown-black pulverulent substance, regarded by some chemistsas a suboxide of arsenic. Arsenic oxidizes when it isheated in the air or in oxygen. If a small quantity of arsenicbe thrown upon a red-hot coal,white vapors are produced, andan
. Elements of modern chemistry . ts density isabout Arsenic volatilizes without melting at a temperature belowdull redness. Its vapor is colorless. When it is heated understrong pressure it melts to a transparent liquid. On exposureto the air it loses its lustre and assumes a black-gray color ; inthis case its surface becomes covered with a thin layer of abrown-black pulverulent substance, regarded by some chemistsas a suboxide of arsenic. Arsenic oxidizes when it isheated in the air or in oxygen. If a small quantity of arsenicbe thrown upon a red-hot coal,white vapors are produced, andan alliaceous odor is percep-tible. A fragment of arsenic maybe strongly heated in the hori-zontal branch of a tube con-taining oxygen (Fig. 71) ; themetal takes fire and burns with ^ ^^ bluish flame, producing white vapors of arsenious oxide. If arsenic be preserved from the air under a layer of water,in which it is insoluble, it oxidizes slowly, in such a manner asto form a small quantity of arsenious acid, which dissolves in H*. 178 ELEMENTS OF MODERN CHEMISTRY. the water. This property explains the efficacy of powderedarsenic (commercial cobalt) for poisoning flies. If powdered arsenic be sprinkled into dry chlorine, eachparticle burns with a bright flash. The arsenic unites with thechlorine, being converted into the trichloride AsCP. It alsocombines directly with bromine, with iodine, and with sulphur. Arsenic is used to harden shot to prevent the leading offowling-pieces. HYDROGEN ARSENIDE (ARSINE). Density compared to hydrogen 39. Molecular weight AsH^ =78. Preparation.—This gas may be prepared by the action ofhydrochloric acid upon zinc arsenide. Zn^As^ + 6HC1 = 2A.^W + 3ZnCP Zinc arsenide. Zinc chloride. It must be handled with prudence, as it is extremely poisonous. Properties.—Hydrogen arsenide is colorless; its odor ispenetrating and garlicky. At a red heat it is decomposedinto arsenic and hydrogen. On the application of flame, itburns in the air with a bluish lig
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