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narwhal

(Encyclopedia)narwhal närˈwəl [key], a small arctic whale, Monodon monoceros. The males of the species, and an occasional female, bear a single, tightly spiraled tusk that measures up to 9 ft (2.7 m) in length. ...

neutralization

(Encyclopedia)neutralization, chemical reaction, according to the Arrhenius theory of acids and bases, in which a water solution of acid is mixed with a water solution of base to form a salt and water; this reactio...

Pascal, Blaise

(Encyclopedia)Pascal, Blaise blĕz päskälˈ [key], 1623–62, French scientist and religious philosopher. Studying under the direction of his father, a civil servant, Pascal showed great precocity, especially in ...

number theory

(Encyclopedia)number theory, branch of mathematics concerned with the properties of the integers (the numbers 0, 1, −1, 2, −2, 3, −3, …). An important area in number theory is the analysis of prime number...

asbestos, mineral

(Encyclopedia)asbestos, common name for any of a variety of silicate minerals within the amphibole and serpentine groups that are fibrous in structure and more or less resistant to acid and fire. Chrysotile asbesto...

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...

poisonous plant

(Encyclopedia)poisonous plant, any plant possessing a property injurious to man or animal. Plants may be poisonous to the touch (e.g., poison ivy, poison sumac), or orally toxic (e.g., poison hemlock, deadly amanit...

polonium

(Encyclopedia)polonium pəlōˈnēəm [key], radioactive chemical element; symbol Po; at. no. 84; mass no. of most stable isotope 209; m.p. 254℃; b.p. 962℃; sp. gr. about 9.4; valence +2 or +4. Polonium is an e...

Bakelite

(Encyclopedia)Bakelite bāˈkəlīt [key] [for its inventor, L. H. Baekeland], synthetic thermosetting resin. It has been widely used both alone, to form whole objects, and in combination with other materials, as a...

californium

(Encyclopedia)californium kălˈĭfôrˌnēəm [key] [from California], artificially produced, radioactive metallic chemical element; symbol Cf; at. no. 98; mass no. of most stable isotope 251; m.p. about 900℃; b...