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potassium nitrate

(Encyclopedia)potassium nitrate, chemical compound, KNO3, occurring as colorless, prismatic crystals or as a white powder; it is found pure in nature as the mineral saltpeter, or niter. (The name saltpeter is also ...

Semyonov, Nikolay Nikolayevich

(Encyclopedia)Semyonov, Nikolay Nikolayevich, or Nikolai Nikolaevic Semenov, 1896–1986, Soviet physical chemist, Ph.D. Petrograd Univ., 1917. Semyonov was a professor at the Leningrad Physico-Technical Institute ...

Orbiting Astronomical Observatory

(Encyclopedia)Orbiting Astronomical Observatory (OAO), series of four orbiting observatories (see observatory, orbiting) launched between 1966 and 1972 by the National Aeronautics and Space Administration (NASA) to...

Kiruna

(Encyclopedia)Kiruna kēˈrünä [key], city (1990 pop. 20,470), Norrbotten co., N Sweden. The northernmost city in Sweden, it is the center of the Lapland iron-mining region. The ore is shipped on the Lapland rail...

Churchill, town, Canada

(Encyclopedia)Churchill, town, NE Manitoba, Canada, a remote port on Hudson Bay at the mouth of the Churchill River. The northern terminus of the Hudson Bay Railway, ...

firing

(Encyclopedia)firing, process of treating clay or other plastic ceramic materials with heat to produce a hard, durable but brittle material such as pottery. Primitive potters baked their clay in an open fire, but f...

space station

(Encyclopedia)space station or space platform, artificial earth satellite, usually manned, that is placed in a fixed orbit and can serve as a base for astronomical observations; zero-gravity materials processing; s...

ammonium nitrate

(Encyclopedia)ammonium nitrate, chemical compound, NH4NO3, that exists as colorless, rhombohedral crystals at room temperature but changes to monoclinic crystals when heated above 32℃. It is extremely soluble in ...

winter cress

(Encyclopedia)winter cress or upland cress, species of Barbarea, herbs of the family Cruciferae (or Brassicaceae; mustard family). The pungent leaves of several species have been used for salads or garnishes, and t...

Blagoveshchensk

(Encyclopedia)Blagoveshchensk bləgəvyĕshˈchĭnsk [key], city, capital of Amur region, Russian Far East, at the confluence ...