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bismuth

(Encyclopedia)bismuth bĭzˈməth [key] [Ger. Weisse Masse=white mass], metallic chemical element; symbol Bi; at. no. 83; at. wt. 208.98040; m.p. 271.3℃; b.p. about 1,560℃; sp. gr. 9.75 at 20℃; valence +3 or ...

Stella, Frank

(Encyclopedia)Stella, Frank, 1936–, American artist, b. Malden, Mass. In his early “black paintings” Stella exhibits the precision and rationality that characterized minimalism, employing parallel angular str...

pound

(Encyclopedia)pound, abbr. lb, unit of either mass or force in the customary system of English units of measurement. Two different pounds of mass are defined, one in the avoirdupois system of units and one in the T...

polar front

(Encyclopedia)polar front, zone of transition between polar and tropical air masses. Its average position during the winter is at about 30° lat. and during the summer at about 60° lat. In the N Atlantic Ocean, fo...

right of way

(Encyclopedia)right of way, in land and air traffic and in sea navigation, rules that determine precedence in the use of traffic lanes. The rules are framed in the simplest possible terms and with nearly absolute u...

root, in botany

(Encyclopedia)CE5 Longitudinal cross section of a root root, in botany, the descending axis of a plant, as contrasted with the stem, the ascending axis. In most plants the root is underground, but in epiphytes ...

Lyon, Mary

(Encyclopedia)Lyon, Mary līˈən [key], 1797–1849, American educator, founder of Mt. Holyoke College, b. Buckland, Mass. She attended three academies in Massachusetts; later she taught at Ashfield, Mass., London...

evaporation

(Encyclopedia)evaporation, change of a liquid into vapor at any temperature below its boiling point. For example, water, when placed in a shallow open container exposed to air, gradually disappears, evaporating at ...

Douhet, Giulio

(Encyclopedia)Douhet, Giulio jo͞oˈlyō do͞oāˈ [key], 1869–1930, Italian military officer and early advocate of airpower. He was an early supporter of strategic bombing and the military superiority of air for...

refraction

(Encyclopedia)refraction, in physics, deflection of a wave on passing obliquely from one transparent medium into a second medium in which its speed is different, as the passage of a light ray from air into glass. O...