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strontium

(Encyclopedia)strontium strŏnˈshēəm [key] [from Strontian, a Scottish town], a metallic chemical element; symbol Sr; at. no. 38; at. wt. 87.62; m.p. 769℃; b.p. 1,384℃; sp. gr. 2.6 at 20℃; valence +2. Stro...

poison gas

(Encyclopedia)poison gas, any of various gases sometimes used in warfare or riot control because of their poisonous or corrosive nature. These gases may be roughly grouped according to the portal of entry into the ...

coenzyme

(Encyclopedia)coenzyme kō-ĕnˈzīm [key], any one of a group of relatively small organic molecules required for the catalytic function of certain enzymes. A coenzyme may either be attached by covalent bonds to a ...

Cronstedt, Axel Fredrik, Baron

(Encyclopedia)Cronstedt, Axel Fredrik, Baron äkˈsəl frāˈdrĭk, kro͞onˈstĕt [key], 1722–65, Swedish mineralogist and chemist. In 1751 he discovered in niccolite an impure form of nickel, reported it as a n...

Dacron

(Encyclopedia)Dacron dāˈkrŏn, dăkˈrŏn [key], trademark for a polyester fiber. Dacron is a condensation polymer obtained from ethylene glycol and terephthalic acid. Its properties include high tensile strength...

Hinshelwood, Sir Cyril Norman

(Encyclopedia)Hinshelwood, Sir Cyril Norman, 1897–1967, British chemist, D.Sc. Oxford, 1924. In 1937 Hinshelwood became a professor at Oxford, where he remained until his retirement in 1964. He shared the 1956 No...

ammonium sulfate

(Encyclopedia)ammonium sulfate, chemical compound, (NH4)2SO4, a colorless-to-gray, rhombohedral crystalline substance that occurs in nature as the mineral mascagnite. It is soluble in water and insoluble in alcohol...

Jennings, Herbert Spencer

(Encyclopedia)Jennings, Herbert Spencer, 1868–1947, American zoologist, b. Tonica, Ill., B.S. Univ. of Michigan, 1893, Ph.D. Harvard, 1896. He was professor of zoology at Johns Hopkins (1906–10) and did researc...

ash, in chemistry

(Encyclopedia)ash, in chemistry, solid residue of combustion. The chemical composition of an ash depends on that of the substance burned. Wood ash contains metal carbonates (e.g., potassium carbonate) and oxides fo...

marcasite

(Encyclopedia)marcasite märˈkəsīt [key] or white iron pyrites, a mineral closely resembling and having the same chemical composition (FeS2) as pyrite. It differs from pyrite in that it is paler in color, become...