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Barton, Derek H. R.

(Encyclopedia)Barton, Derek H. R., 1918–98, British chemist, b. Gravesend, England, grad. Imperial College of Science and Technology (B.S. 1940, Ph.D. 1942, D.Sc. 1949). He was on the faculty of Imperial College ...

luminescence

(Encyclopedia)luminescence, general term applied to all forms of cool light, i.e., light emitted by sources other than a hot, incandescent body, such as a blackbody radiator. Luminescence is caused by the movement ...

thermionic emission

(Encyclopedia)thermionic emission thûrmˌīŏnˈĭk [key], emission of electrons or ions by substances that are highly heated, the charged particles being called thermions. The number of thermions emitted increase...

arsenopyrite

(Encyclopedia)arsenopyrite mĭsˈpĭkəl [key], silver-white to steel-gray mineral with the metallic luster characteristic of a pyrite. It is a sulfarsenide of iron, FeAsS, crystallizing in the orthorhombic system ...

limonite

(Encyclopedia)limonite hĕmˈətīt, hēˈ– [key], yellowish to dark brown mineral, a hydrated oxide of iron, FeO(OH)·nH2O, occurring commonly in deposits of secondary origin, i.e., those formed by the alteratio...

heat exhaustion

(Encyclopedia)heat exhaustion, condition caused by overexposure to sunlight or another heat source and resulting in dehydration and salt depletion, also known as heat prostration. The symptoms are severe headaches,...

Hoffmann, Friedrich

(Encyclopedia)Hoffmann, Friedrich hôfˈmän [key], 1660–1742, German physician. He taught and practiced at Halle from 1693. He studied and wrote on such varied topics as pediatrics, mineral waters, and meteorol...

Joplin

(Encyclopedia)Joplin jŏpˈlĭn [key], city (1990 pop. 40,961), Jasper and Newton counties, SW Mo., at the edge of the Ozarks; settled c.1839, inc. 1873. It is a railroad center, the shipping and processing point o...

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...

cesium

(Encyclopedia)cesium sēˈzēəm [key] [Lat.,=bluish gray], a metallic chemical element; symbol Cs; at. no. 55; at. wt. 132.90545; m.p. 28.4℃; b.p. 669.3℃; sp. gr. 1.873 at 20℃; valence +1. Cesium is a ductil...