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superconductivity

(Encyclopedia)superconductivity, abnormally high electrical conductivity of certain substances. The phenomenon was discovered in 1911 by Heike Kamerlingh Onnes, who found that the resistance of mercury dropped sudd...

Priestley, Joseph

(Encyclopedia)Priestley, Joseph, 1733–1804, English theologian and scientist. He prepared for the Presbyterian ministry and served several churches in England as pastor but gradually rejected orthodox Calvinism a...

Mexico, city, Mexico

(Encyclopedia)Mexico or Mexico City, Span. Ciudad de México (Méjico), city (1990 pop. 8,236,960; 1991 met. area est. 20,899,000), central Mexico, capital and largest city of Mexico. The city has been the met...

air pollution

(Encyclopedia)air pollution, contamination of the air by noxious gases and minute particles of solid and liquid matter (particulates) in concentrations that endanger health. The major sources of air pollution are t...

volcano

(Encyclopedia)volcano, vents or fissures in the earth's crust through which gases, molten rock, or lava, and solid fragments are discharged. Their study is called volcanology. The term volcano is commonly applied b...

diesel engine

(Encyclopedia)diesel engine, type of internal-combustion engine invented by the German engineer Rudolf Diesel and patented by him in 1892. Although his engine was designed to use coal dust as fuel, the diesel engin...

cheese

(Encyclopedia)cheese, food known from ancient times and consisting of the curd of milk separated from the whey. The numerous cheeses (often named for their place of origin) depend for their distinctive qualities ...

Marseilles

(Encyclopedia)Marseilles märsāˈ [key], Fr. Marseille, city (1990 pop. 807,726), capital of Bouches-du-Rhône dept., SE France, on the Gulf of Lions, an arm of the Mediterranean Sea. It is the second largest city...

Mercury, in astronomy

(Encyclopedia)Mercury, in astronomy, nearest planet to the sun, at a mean distance of 36 million mi (58 million km); its period of revolution is 88 days. Mercury passes through phases similar to those of the moon a...

hydrogen

(Encyclopedia)hydrogen hīˈdrəjən [key] [Gr.,=water forming], gaseous chemical element; symbol H; at. no. 1; interval in which at. wt. ranges 1.00784–1.00811; m.p. −259.14℃; b.p. −252.87℃; density 0.08...