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Davy, Sir Humphry

(Encyclopedia)Davy, Sir Humphry, 1778–1829, English chemist and physicist. The son of a woodcarver, he received his early education at Truro and was apprenticed (1795) to a surgeon-apothecary at Penzance. While d...

Urey, Harold Clayton

(Encyclopedia)Urey, Harold Clayton yo͝orˈē [key], 1893–1981, American chemist, b. Walkerton, Ind., grad. Univ. of Montana (B.S., 1917), Ph.D. Univ. of California, 1923. He taught at Johns Hopkins (1924–29), ...

cobalt, chemical element

(Encyclopedia)cobalt, metallic chemical element; symbol Co; at. no. 27; at. wt. 58.9332; m.p. 1,495℃; b.p. about 2,870℃; sp. gr. 8.9 at 20℃; valence +2 or +3. Cobalt is a silver-white, lustrous, hard, brittle...

Lamb, Willis Eugene, Jr.

(Encyclopedia)Lamb, Willis Eugene, Jr., 1913–2008, American physicist, b. Los Angeles, Ph.D. Univ. of California, Berkeley, 1938. Lamb was a professor at Columbia (1938–51), Stanford (1951–56), Oxford (1956�...

Freon

(Encyclopedia)Freon frēˈŏn [key] [trade name], any one of a special class of chemical compounds that are used as refrigerants, aerosol propellants, and solvents. These compounds are haloalkanes, i.e., halogen de...

Andrée, Salomon August

(Encyclopedia)Andrée, Salomon August säˈlo͞omôn ouˈgəst ändrāˈ [key], 1854–97, Swedish polar explorer, grad. Royal Inst. of Technology, Stockholm. An aeronautical engineer and head of the Swedish patent...

ammonium group

(Encyclopedia)ammonium group, in chemistry, a positively charged nitrogen atom joined by single bonds to four other atoms or groups. The simplest ammonium group, NH4+, is formed by protonation of ammonia, NH3, e.g....

fusion

(Encyclopedia)fusion, in physics. 1 The change of a substance from the solid to the liquid state, also known as melting. The heat given up by a unit mass of a substance during fusion is called the latent heat of fu...

Sakharov, Andrei Dmitriyevich

(Encyclopedia)Sakharov, Andrei Dmitriyevich, 1921–89, Soviet nuclear physicist and human-rights advocate; first Soviet citizen to receive the Nobel Peace Prize (1975). From 1948 to 1956 he helped to develop the U...

Ramsey, Norman Foster, Jr.

(Encyclopedia)Ramsey, Norman Foster, Jr., 1915–2011, American physicist, b. Washington, D.C., Ph.D. Columbia, 1940. A member of the faculty at Harvard from 1947 and the Higgins professor of physics from 1966 (eme...