Columbia Encyclopedia

Search results

260 results found

ozone

(Encyclopedia)ozone ōˈzōn [key], an allotropic form of the chemical element oxygen (see allotropy). Pure ozone is an unstable, faintly bluish gas with a characteristic fresh, penetrating odor. The gas has a dens...

polymerase chain reaction

(Encyclopedia)polymerase chain reaction pŏlˈĭmərāsˌ [key] (PCR), laboratory process in which a particular DNA segment from a mixture of DNA chains is rapidly replicated, producing a large, readily analyzed sa...

vapor pressure

(Encyclopedia)vapor pressure, pressure exerted by a vapor that is in equilibrium with its liquid. A liquid standing in a sealed beaker is actually a dynamic system: some molecules of the liquid are evaporating to f...

Grand Army of the Republic

(Encyclopedia)Grand Army of the Republic (GAR), organization established by Civil War veterans of the Union army and navy. Principal figures in the founding of the GAR were John A. Logan and Richard J. Oglesby. The...

Port Authority of New York and New Jersey

(Encyclopedia)Port Authority of New York and New Jersey, self-sustaining public corporation established in 1921 by the states of New York and New Jersey to administer the activities of the New York–New Jersey por...

Treasury, United States Department of the

(Encyclopedia)Treasury, United States Department of the, federal executive department established in 1789. It is charged with advising the president on fiscal policy and acting as fiscal agent for the federal gover...

zebra

(Encyclopedia)zebra, herbivorous hoofed African mammal of the genus Equus, which also includes the horse and the ass. It is distinguished by its striking pattern of black or dark brown stripes alternating with whit...

Williams, Roger

(Encyclopedia)Williams, Roger, c.1603–1683, clergyman, advocate of religious freedom, founder of Rhode Island, b. London. A protégé of Sir Edward Coke, he graduated from Pembroke College, Cambridge, in 1627 and...

Saratoga campaign

(Encyclopedia)Saratoga campaign, June–Oct., 1777, of the American Revolution. Lord George Germain and John Burgoyne were the chief authors of a plan to end the American Revolution by splitting the colonies along ...

complex ion

(Encyclopedia)complex ion, charged molecular aggregate (see ion), consisting of a metallic atom or ion to which is attached one or more electron-donating molecules. In some complex ions, such as sulfate, SO4−2, t...