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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...

pigment

(Encyclopedia)pigment, substance that imparts color to other materials. In paint, the pigment is a powdered substance which, when mixed in the liquid vehicle, imparts color to a painted surface. The pigments used i...

Fischer, Hans

(Encyclopedia)Fischer, Hans, 1881–1945, German organic chemist, Ph.D. Univ. of Marburg, 1904; M.D. Univ. of Munich, 1908. Fischer was a professor at the Univ. of Innsbruck from 1916 to 1918 and at the Univ. of Vi...

silicon carbide

(Encyclopedia)silicon carbide, chemical compound, SiC, that forms extremely hard, dark, iridescent crystals that are insoluble in water and other common solvents. Widely used as an abrasive, it is marketed under su...

photographic processing

(Encyclopedia)photographic processing, set of procedures by which the latent, or invisible, image produced when a photographic film is exposed to light is made into a permanent visible image. The negative may b...

podzol

(Encyclopedia)podzol pŏdˈsŏl [key] or podzolic soil, member of a group of soils that are gray in color, have an ashy appearance, and extend immediately south of the tundra regions of the Northern Hemisphere. Alt...

soil

(Encyclopedia)soil, surface layer of the earth, composed of fine rock material disintegrated by geological processes; and humus, the organic remains of decomposed vegetation. In agriculture, soil is the medium that...

Focillon, Henri

(Encyclopedia)Focillon, Henri äNrēˈ fôsēyôNˈ [key], 1881–1943, French art historian. Focillon, who was professor of art history at the Collège de France, was an authority on medieval art, the subject of h...

prosthetic group

(Encyclopedia)prosthetic group, non-amino acid portions of certain protein molecules. The key part of the prosthetic group may be either organic (such as a vitamin) or inorganic (such as a metal) and is usually req...

enthalpy

(Encyclopedia)enthalpy ĕnˈthălpē [key], measure of the heat content of a chemical or physical system; it is a quantity derived from the heat and work relations studied in thermodynamics. As a system changes fro...