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English units of measurement

(Encyclopedia)English units of measurement, principal system of weights and measures used in a few nations, the only major industrial one being the United States. It actually consists of two related systems—the U...

sodium thiosulfate

(Encyclopedia)sodium thiosulfate, Na2S2O3, colorless crystalline compound that is more familiar as the pentahydrate, Na2S2O3·5H2O, an efflorescent, monoclinic crystalline substance also called sodium hyposulfite o...

Goddard, Robert Hutchings

(Encyclopedia)Goddard, Robert Hutchings, 1882–1945, American physicist and rocket expert, b. Worcester, Mass., grad. Worcester Polytechnic Institute (B.S., 1908), Ph.D. Clark Univ., 1911. From 1914 he was associa...

Europa, in astronomy

(Encyclopedia)Europa yo͝orōˈpə [key], in astronomy, one of the 39 known moons, or natural satellites, of Jupiter. Magnetic-field data collected by the space probe Galileo in 2002 strongly indicated a liquid-wat...

chlorate

(Encyclopedia)chlorate pərklōrˈāt, –klôrˈ– [key], salts of chloric acid, HClO3, and perchloric acid, HClO4, respectively. Perchlorates are safer to handle than chlorates; they are more stable when expos...

colloid

(Encyclopedia)colloid kŏlˈoid [key] [Gr.,=gluelike], a mixture in which one substance is divided into minute particles (called colloidal particles) and dispersed throughout a second substance. The mixture is also...

pressure

(Encyclopedia)pressure, in mechanics, ratio of the force acting on a surface to the area of the surface; it is thus distinct from the total force acting on a surface. A force can be applied to and sustained by a si...

Sloane, T(homas) O'Conor

(Encyclopedia)Sloane, T(homas) O'Conor, 1851–1940, American scientist, lecturer, writer, and periodical editor, Ph.D. Columbia, 1876. Sloane was a member of the editorial staff of the Scientific American, where h...

cloaca

(Encyclopedia)cloaca klōāˈkə [key], in biology, enlarged posterior end of the digestive tract of some animals. The cloaca, from the Latin word for sewer, is a single chamber into which pass solid and liquid was...

polystyrene

(Encyclopedia)polystyrene pŏlˌēstīˈrēn [key], widely used plastic; it is a polymer of styrene. Polystyrene is a colorless, transparent thermoplastic that softens slightly above 100℃ (212℉) and becomes a v...