zimocca

[Etym. doubtful.] (See etym. and compound.) zimocca-sponge, s. Zool.: Euspongia zimocca , a sponge with a dark brownish-yellow skeleton, the chief fibers of which are soft, thin, elastic, and almost free from sand, while the under fibers are dense and thick, rendering the sponge itself abnormally hard. zi-mōme, s. [ZYMOME.] zinc, s. [Dan. & Sw. zink; Fr. zinc; cogn. with Ger. zinn = tin.] 1. Astronomy: It has been ascertained by spec troscopy that there is zinc in the sun. 2. Chem. & Comm.: A divalent metallic element, symbol Zn.; atomic weight, 65; found in considerable abundance in many parts of America, in Britain, in Silesia, and in the neighborhood of Aix la Chapelle. It is extracted from the native carbonate by first roasting the ore, mixing it with charcoal or coke, and subjecting the mixture to a full red heat in an earthen retort. The reduced metal volatilizes, and is condensed by suitable means. It is bluish-white, tarnishes slowly in the air, is crystalline and brittle, with a density varying from 6.8 to 7.2. Between 121° and 149° it has the property of becoming malleable, and after such treatment retains this character when cold. At 411° it melts, and at a bright red heat boils and volatilizes. Ordinary zinc di olves readily in dilute acids, but pure zinc is le soluble unle it is in positive metal, with which forme a galvanic contact with platinum, copper, or some other le circuit. Solutions of zinc give a white precipitate with hydric sulphide. In consequence ne and cheapne , sheet zinc is employed for lining baths and cisterns, for gutters, spouts, and roofs; for the latter purpose it is usually corrugated. Zinc plates are much used as generators of electricity in voltaic batteries and in zincography (q. v.). Zinc is also an important factor in the manufacture of alloys, and in the preparation of galvanized iron (q.v.). 3. Pharm .: Oxide of zinc given in small doses is a tonic and astringent, acting beneficially on the nervous system in chorea, epilepsy, hysteria, neuralgia, .; in large doses it is emetic; externally it is a desiccant and astringent. Sulphate of zinc and acetate of zinc produce similar effects. So apparently does the carbonate, which, however, is not much employed medicinally. Chloride of zinc is used externally as an escharotic; valerian ate of zinc is a nervine tonic and antispasmodic, also an anthelmintic. ( Garrod .) Zinc-arsenate Köttigite ; zinc-blende= Blende ; zinc-bloom = Hydrozincite ; zinc carbonate = Cala mine; zinc-oxide = Zincite ; zinc oxysulphide= Volt zite ; zinc-silicate= Hemimorphite and Willemite ; zinc-siliceous oxide = Hemimorphite; zinc-spar = Calamine; zinc-sulphate= Goslarite ; zinc-sulphide = Blende ; zinc-vitriol= Goslarite . IMG:content-1124.png:[blocks in formation] 4579