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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...

harvest customs

(Encyclopedia)harvest customs, practices associated with the celebration of the gathering of agricultural crops. The gathering of the harvest—the climax of the year's labors wherever the soil is cultivated—has ...

Crater Lake National Park

(Encyclopedia)Crater Lake National Park, 183,224 acres (74,206 hectares), SW Oreg., in the Cascade Range; est. 1902. Crater Lake, 20 sq mi (52 sq km), lies in a huge pit that was created when the top of a prehistor...

cider

(Encyclopedia)cider, in Europe, fermented juice of apples; in the United States, unfermented apple juice, unless allowed to ferment, in which case it is typically known as hard cider. Selected apples are grated in ...

podzol

(Encyclopedia)podzol pŏdˈsŏl [key] or podzolic soil, member of a group of soils that are gray in color, have an ashy appearance, and extend immediately south of the tundra regions of the Northern Hemisphere. Alt...

polyester

(Encyclopedia)polyester, synthetic fiber, produced by the polymerization of the product formed when an alcohol and organic acid react. The outstanding characteristic of polyesters is their ability to resist wrinkli...

nylon

(Encyclopedia)nylon, synthetic thermoplastic material characterized by strength, elasticity, resistance to abrasion and chemicals, low moisture absorbency, and capacity to be permanently set by heat. After 10 years...

lime, in botany

(Encyclopedia)lime, in botany, small shrublike tree (Citrus aurantifolia) of the family Rutaceae (rue family), one of the citrus fruit trees, similar to the lemon but more spreading and irregular in growth. The tru...

Grateful Dead, The

(Encyclopedia)Grateful Dead, The, American rock music group formed in 1965 by guitarists Jerry Garcia, 1942–95, and Bob Weir, 1947–, harmonica player Ron “Pigpen” McKernan, 1945–73, bassist Phil Lesh, 194...

detergent

(Encyclopedia)detergent dētûrˈjənt, dĭ– [key], substance that aids in the removal of dirt. Detergents act mainly on the oily films that trap dirt particles. The detergent molecules have a hydrocarbon portion...