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tungsten

(Encyclopedia)tungsten tŭngˈstən [key] [Swed.,=heavy stone], metallic chemical element; symbol W; at. no. 74; at. wt. 183.84; m.p. about 3,410℃; b.p. 5,660℃; sp. gr. 19.3 at 20℃; valence +2, +3, +4, +5, or...

atomic weight

(Encyclopedia)atomic weight, mean (weighted average) of the masses of all the naturally occurring isotopes of a chemical element, as contrasted with atomic mass, which is the mass of any individual isotope. Althoug...

Marggraf, Andreas Sigismund

(Encyclopedia)Marggraf, Andreas Sigismund ändrāˈäs zēˈgĭsmo͝ont märkˈgräfˌ [key], 1709–82, German chemist, a pioneer in analytical chemistry. He proved that alumina, magnesia, and lime are distinct ea...

Kolín

(Encyclopedia)Kolín kôˈlēn [key], city (1991 pop. 31,595), central Czech Republic, in Bohemia, on the Elbe (Labe) River. It is a river port with metal and chemical industries; automobiles are produced nearby. T...

Kopp, Hermann Franz Moritz

(Encyclopedia)Kopp, Hermann Franz Moritz hĕrˈmän fräntz mōˈrĭts kôp [key], 1817–92, German physical chemist and historian of chemistry. His research concerned the connection between the physical propertie...

Helmont, Jan Baptista van

(Encyclopedia)Helmont, Jan Baptista van yän bäptĭsˈtä vän hĕlˈmônt [key], 1577–1644, Flemish physician, chemist, and physicist. He attributed physiological changes to chemical causes, but his conclusions...

Hefei

(Encyclopedia)Hefei or Hofei both: hô-fā [key], city (1994 est. pop. 866,800), capital of Anhui prov., China. A rapidly growing industrial city, it has textile mills, ironworks and steelworks, chemical and food p...

Heyrovsky, Jaroslav

(Encyclopedia)Heyrovsky, Jaroslav, 1890–1967, Czech chemist, Ph.D. Charles Univ. of Prague, 1918; D.Sc. University College, London, 1921. Heyrovsky was director of the Polarography Institute at the Czechoslovak A...

Hodgkin, Sir Alan Lloyd

(Encyclopedia)Hodgkin, Sir Alan Lloyd, 1914–98, English biophysicist. For their work in analyzing the electrical and chemical events in nerve-cell discharge, he and Andrew Huxley shared with Sir John Eccles the 1...

detonator

(Encyclopedia)detonator dĕˈtənāˌtər [key], type of explosive that reacts with great rapidity and is used to set off other, more inert explosives. Fulminate of mercury mixed with potassium chlorate is a common...