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liquid air

(Encyclopedia)liquid air, ordinary air that has been liquefied by compression and cooling to extremely low temperatures (see liquefaction). Its commercial preparation involves purification by washing to remove solu...

adsorption

(Encyclopedia)adsorption, adhesion of the molecules of liquids, gases, and dissolved substances to the surfaces of solids, as opposed to absorption, in which the molecules actually enter the absorbing medium (see a...

sugar

(Encyclopedia)sugar, compound of carbon, hydrogen, and oxygen belonging to a class of substances called carbohydrates. Sugars fall into three groups: the monosaccharides, disaccharides, and trisaccharides. The mono...

United States Naval Observatory

(Encyclopedia)United States Naval Observatory, a federal astronomical observatory, located in Washington, D. C. It evolved from the Navy's oldest scientific institution, the Depot of Charts and Instruments, founded...

Feynman, Richard Phillips

(Encyclopedia)Feynman, Richard Phillips fīnˈmən [key], 1918–88, American physicist, b. New York City, B.S. Massachusetts Institute of Technology, 1939, Ph.D. Princeton, 1942. From 1942 to 1945 he worked on the...

Potsdam Conference

(Encyclopedia)Potsdam Conference, meeting (July 17–Aug. 2, 1945) of the principal Allies in World War II (the United States, the USSR, and Great Britain) to clarify and implement agreements previously reached at ...

nucleus, in physics

(Encyclopedia)nucleus, in physics, the extremely dense central core of an atom. Following the discovery of radioactivity by A. H. Becquerel in 1896, Ernest Rutherford identified two types of radiation given off b...

gas, fuel

(Encyclopedia)gas, fuel, gaseous substance that burns in air and releases enough heat to be useful as a fuel, while also remaining sufficiently stable at ordinary temperatures to permit long-term storage without de...

aqua regia

(Encyclopedia)aqua regia rēˈjēə [key] [Lat.,=royal water], corrosive, fuming yellow liquid prepared by mixing one volume of concentrated nitric acid with three to four volumes of concentrated hydrochloric acid....

nonmetal

(Encyclopedia)nonmetal, chemical element possessing certain properties by which it is distinguished from a metal. In general, this distinction is drawn on the basis that a nonmetal tends to accept electrons and for...