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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...

plastic

(Encyclopedia)plastic, any organic material with the ability to flow into a desired shape when heat and pressure are applied to it and to retain the shape when they are withdrawn. The first important plastic, cel...

energy, sources of

(Encyclopedia)energy, sources of, origins of the power used for transportation, for heat and light in dwelling and working areas, and for the manufacture of goods of all kinds, among other applications. The develop...

locomotive

(Encyclopedia)locomotive, vehicle used to pull a train of unpowered railroad cars. Richard Trevithick, a British engineer and inventor, built and operated (1803–4) the first successful steam engine locomotive f...

art conservation and restoration

(Encyclopedia)art conservation and restoration, the preservation of structurally sound works of art, the halting of processes that lead to the damage of works of art, and the repair of already damaged works of art....

Chinese

(Encyclopedia)Chinese, subfamily of the Sino-Tibetan family of languages (see Sino-Tibetan languages), which is also sometimes grouped with the Tai, or Thai, languages in a Sinitic subfamily of the Sino-Tibetan lan...

glass

(Encyclopedia)glass, hard substance, usually brittle and transparent, composed chiefly of silicates and an alkali fused at high temperature. Glass has become invaluable in modern architecture, illumination, elect...

flight

(Encyclopedia)CE5 Aircraft motions and control surfaces: Yaw, or motion to the left or right, is controlled by the rudder. Pitch, or climbing or dropping, is controlled by the elevators, which move in the same d...

elephant

(Encyclopedia)elephant, largest living land mammal, found in tropical regions of Africa and Asia. Elephants have massive bodies and heads, thick, pillarlike legs, and broad, short padded feet, with toes bearing hea...

submarine

(Encyclopedia)submarine, naval craft capable of operating for an extended period of time underwater. Submarines are almost always warships, although a few are used for scientific, business, or other purposes (see a...