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specific heat

(Encyclopedia)specific heat, ratio of the heat capacity of a substance to the heat capacity of a reference substance, usually water. Heat capacity is the amount of heat needed to change the temperature of a unit ma...

oxidation and reduction

(Encyclopedia)oxidation and reduction, complementary chemical reactions characterized by the loss or gain, respectively, of one or more electrons by an atom or molecule. Originally the term oxidation was used to re...

lead acetate

(Encyclopedia)lead acetate, chemical compound, a white crystalline substance with a sweetish taste. Like other lead compounds, it is very poisonous. Lead acetate is soluble in water and glycerin. With water it form...

half-life

(Encyclopedia)half-life, measure of the average lifetime of a radioactive substance (see radioactivity) or an unstable subatomic particle. One half-life is the time required for one half of any given quantity of th...

chelating agents

(Encyclopedia)chelating agents kēˈlātĭng [key]. Certain organic compounds are capable of forming coordinate bonds (see chemical bond) with metals through two or more atoms of the organic compound; such organic ...

speech defect

(Encyclopedia)speech defect, any condition that interferes with the mental formation of words or their physical production. Speech defects in children generally become apparent in the early school years. Speech pro...

coal

(Encyclopedia)coal, fuel substance of plant origin, largely or almost entirely composed of carbon with varying amounts of mineral matter. Coal is found in beds or seams interstratified with shales, clays, sands...

expansion

(Encyclopedia)expansion, in physics, increase in volume resulting from an increase in temperature. Contraction is the reverse process. When heat is applied to a body, the rate of vibration and the distances between...

jasper, type of quartz

(Encyclopedia)jasper, opaque, impure cryptocrystalline quartz, usually red, but also yellow, green, and grayish blue. It is used as a gem. Ribbon jasper has the colors in stripes. ...

Mar, John Erskine, 2d (or 7th) earl of

(Encyclopedia)Mar, John Erskine, 2d (or 7th) earl of, 1558–1634, Scottish nobleman; son of the 1st (or 6th) earl. In 1578 he was persuaded by James Douglas, 4th earl of Morton, to assert his claims to Stirling Ca...