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chromosphere

(Encyclopedia)chromosphere krōˈməsfērˌ [key] [Gr.,=color sphere], layer of rarefied, transparent gases in the solar atmosphere; it measures 6,000 mi (9,700 km) in thickness and lies between the photosphere (th...

soil

(Encyclopedia)soil, surface layer of the earth, composed of fine rock material disintegrated by geological processes; and humus, the organic remains of decomposed vegetation. In agriculture, soil is the medium that...

meteorite

(Encyclopedia)meteorite, meteor that survives the intense heat of atmospheric friction and reaches the earth's surface. Because of the destructive effects of this friction, only the very largest meteors become mete...

Tuscany

(Encyclopedia)Tuscany tŭsˈkənē [key], Ital. Toscana, region (1991 pop. 3,538,619), 8,876 sq mi (22,989 sq km), N central Italy, bordering on the Tyrrhenian Sea in the west and including the Tuscan Archipelago. ...

calcium

(Encyclopedia)calcium kălˈsēəm [key] [Lat.,=lime], metallic chemical element; symbol Ca; at. no. 20; at. wt. 40.078; m.p. about 839℃; b.p. 1,484℃; sp. gr. 1.55 at 20℃; valence +2. Calcium is a malleable, ...

metallurgy

(Encyclopedia)metallurgy mĕtˈəlûrˌjē [key], science and technology of metals and their alloys. Modern metallurgical research is concerned with the preparation of radioactive metals, with obtaining metals econ...

salt, chemical compound

(Encyclopedia)salt, chemical compound (other than water) formed by a chemical reaction between an acid and a base (see acids and bases). Salts are also prepared by methods other than neutralization. A metal can c...

fire fighting

(Encyclopedia)fire fighting, the use of strategy, personnel, and apparatus to extinguish, to confine, or to escape from fire. Ancient Rome is known to have had a fire department consisting by the 1st cent. of app...

Michigan

(Encyclopedia)CE5 Michigan mĭshˈĭgən [key], upper midwestern state of the United States. It consists of two peninsulas thrusting into the Great Lakes and has borders with Ohio and Indiana (S), Wisconsin (W),...

nutrition

(Encyclopedia)nutrition, study of the materials that nourish an organism and of the manner in which the separate components are used for maintenance, repair, growth, and reproduction. Nutrition is achieved in vario...