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lead, chemical element

(Encyclopedia)lead, metallic chemical element; symbol Pb [Lat. plumbum]; at. no. 82; at. wt. 207.2; m.p. 327.502℃; b.p. about 1,740℃; sp. gr. 11.35 at 20℃; valence +2 or +4. One of the oldest metals used by h...

West Indies

(Encyclopedia)CE5 West Indies, archipelago, between North and South America, curving c.2,500 mi (4,020 km) from Florida to the coast of Venezuela and separating the Caribbean Sea and the Gulf of Mexico from the ...

Wordsworth, William

(Encyclopedia)Wordsworth, William, 1770–1850, English poet, b. Cockermouth, Cumberland. One of the great English poets, he was a leader of the romantic movement in England. Wordsworth's personality and poetry ...

Chinese architecture

(Encyclopedia)Chinese architecture, the buildings and other structures created in China from prehistoric times to the present day. Since the late 19th cent. the Chinese have adopted European architectural styles....

mountain

(Encyclopedia)mountain, high land mass projecting conspicuously above its surroundings and usually of limited width at its summit. Although isolated mountains are not unusual, mountains commonly form ranges, compri...

nuclear reactor

(Encyclopedia)CE5 Power reactor system nuclear reactor, device for producing controlled release of nuclear energy. Reactors can be used for research or for power production. A research reactor is designed to pr...

uranium

(Encyclopedia)uranium yo͞orāˈnēəm [key], radioactive metallic chemical element; symbol U; at. no. 92; mass number of most stable isotope 238; m.p. 1,132℃; b.p. 3,818℃; sp. gr. 19.1 at 25℃; valence +3, +4...

sound

(Encyclopedia)CE5 Sound waves: An air pressure wave radiating outward from a loudspeaker is perceived as sound. sound, any disturbance that travels through an elastic medium such as air, ground, or water to be ...

space medicine

(Encyclopedia)space medicine, study of the medical and biological effects of space travel on living organisms. The principal aim is to discover how well and for how long humans can withstand the extreme conditions ...

Puritanism

(Encyclopedia)Puritanism, in the 16th and 17th cent., a movement for reform in the Church of England that had a profound influence on the social, political, ethical, and theological ideas of England and America. ...