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silver chloride

(Encyclopedia)silver chloride, chemical compound, AgCl, a white cubic crystalline solid. It is nearly insoluble in water but is soluble in a water solution of ammonia, potassium cyanide, or sodium thiosulfate (“h...

impressionism, in painting

(Encyclopedia)impressionism, in painting, late-19th-century French school that was generally characterized by the attempt to depict transitory visual impressions, often painted directly from nature, and by the use ...

color index

(Encyclopedia)color index, in astronomy, difference in an object's brightness as recorded between any two well-defined bands of the electromagnetic spectrum by using optical filters of different colors. If blue and...

Turrell, James

(Encyclopedia)Turrell, James, 1943–, American installation and land artist, b. Los Angeles, grad. Pomona College (B.A., 1965), Claremont Graduate School (M.F.A., 1973). Turrell's career began in the 1960s art sce...

Huygens, Christiaan

(Encyclopedia)Huygens, Christiaan krĭsˈtyän hoiˈgəns [key], 1629–95, Dutch mathematician and physicist; son of Constantijn Huygens. He improved telescopic lenses and discovered (1655) a satellite of Saturn a...

rum

(Encyclopedia)rum, spirituous liquor made from fermented sugarcane products. Prepared by fermentation, distillation, and aging, it is made from the molasses and foam that rise to the top of boiled sugarcane juice. ...

lighthouse

(Encyclopedia)lighthouse, towerlike structure erected to give guidance and warning to ships and aircraft by either visible or radioelectrical means. Lighthouses were long built to conform in structure to their geog...

green flash

(Encyclopedia)green flash or emerald flash, a refractive phenomenon of the atmosphere where the top edge of the setting (or, less frequently, rising) sun will momentarily turn emerald green. The green color lasts f...

sky

(Encyclopedia)sky, apparent dome over the earth, background of the clouds, sun, moon, and stars. The blue color of the clear daytime sky results from the selective scattering of light rays by the minute particles o...

ophthalmoscope

(Encyclopedia)ophthalmoscope ŏfthălˈməskōpˌ [key], instrument used for examining the inner structure of the eye. The device was invented by the German physiologist H. L. F. von Helmholtz in 1851. His model co...