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chemical reaction

(Encyclopedia)chemical reaction, process by which one or more substances may be transformed into one or more new substances. Energy is released or is absorbed, but no loss in total molecular weight occurs. When, fo...

cloud chamber

(Encyclopedia)cloud chamber, device used to detect elementary particles and other ionizing radiation. A cloud chamber consists essentially of a closed container filled with a supersaturated vapor, e.g., water in ai...

Altai

(Encyclopedia)Altai or Altay both: ăltīˈ, äl–, ălˈtī, Rus. əltīˈ [key], geologically complex mountain system of central Asia; largely in the Altai Republic, Russia, and in Kazakhstan, but extending into...

shaft sinking

(Encyclopedia)shaft sinking, excavation from the surface of an opening in the earth. Shafts, which are generally vertical, are usually distinguished from tunnels, which are horizontal. Little difficulty is experien...

stoneware

(Encyclopedia)stoneware, hard pottery made from siliceous paste, fired at high temperature to vitrify (make glassy) the body. Stoneware is heavier and more opaque than porcelain and differs from terra-cotta in bein...

strength of materials

(Encyclopedia)strength of materials, measurement in engineering of the capacity of metal, wood, concrete, and other materials to withstand stress and strain. Stress is the internal force exerted by one part of an e...

Cepheid variables

(Encyclopedia)Cepheid variables sēˈfēĭd [key], class of variable stars that brighten and dim in an extremely regular fashion. The periods of the fluctuations (the time to complete one cycle from bright to dim a...

weather balloon

(Encyclopedia)weather balloon, balloon used in the measurement and evaluation of mostly upper atmospheric conditions (see atmosphere). Information may be gathered during the vertical ascent of the balloon through t...

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...

wind

(Encyclopedia)wind, flow of air relative to the earth's surface. A wind is named according to the point of the compass from which it blows, e.g., a wind blowing from the north is a north wind. The diurnal, or dai...