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gas mask

(Encyclopedia)gas mask, face covering or device used to protect the wearer from injurious gases and other noxious materials by filtering and purifying inhaled air. In addition to military use (see chemical warfare)...

Hofmann, August Wilhelm von

(Encyclopedia)Hofmann, August Wilhelm von ouˈgo͝ost vĭlˈhĕlm fən hôfˈmän [key], 1818–92, German organic chemist. He was professor at the Univ. of Berlin from 1865 and was a founder (1868) of the German C...

Almería

(Encyclopedia)Almería älmārēˈä [key], city, capital of Almería prov., SE Spain, in Andalusia, on the Gulf of Almería. A busy Mediterranean port, it exports the celebrated grapes...

Harlingen

(Encyclopedia)Harlingen härˈlĭnjən [key], city (2020 pop. 71,829), Cameron co., extreme S Tex.; inc. 1910. It ...

Kamyanske

(Encyclopedia)Kamyanske, formerly Dniprodzerzhynsk dənyĭpˌrōdzĭrzhēnskˈ [key], Rus. Dneprodzerzhinsk, city (1989 pop. 282,000), central Ukraine, a port on the Dnieper River. It is a major industrial center w...

calcium carbonate

(Encyclopedia)calcium carbonate, CaCO3, white chemical compound that is the most common nonsiliceous mineral. It occurs in two crystal forms: calcite, which is hexagonal, and aragonite, which is rhombohedral. Calci...

castor bean

(Encyclopedia)castor bean, bean produced by Ricinus communis, a plant of the spurge family, widely cultivated as an ornamental. Moles die when they eat the roots. It has long been used as an ordeal poison in parts ...

metallurgy

(Encyclopedia)metallurgy mĕtˈəlûrˌjē [key], science and technology of metals and their alloys. Modern metallurgical research is concerned with the preparation of radioactive metals, with obtaining metals econ...

uranium

(Encyclopedia)uranium yo͞orāˈnēəm [key], radioactive metallic chemical element; symbol U; at. no. 92; mass number of most stable isotope 238; m.p. 1,132℃; b.p. 3,818℃; sp. gr. 19.1 at 25℃; valence +3, +4...

radium

(Encyclopedia)radium rāˈdēəm [key] [Lat. radius=ray], radioactive metallic chemical element; symbol Ra; at. no. 88; mass number of most stable isotope 226; m.p. 700℃; b.p. 1,140℃; sp. gr. about 6.0; valence...