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Smithson Tennant
Smithson Tennant 1761-1815, English chemist. In 1796 he proved, by burning a diamond, that the diamond consists solely of carbon. In 1804 he announced his discovery of osmium and iridium.
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James Bradley
James Bradley 1693-1762, English astronomer. His discovery of the aberration of light, announced in 1728, provided an important line of evidence for the motion of the earth around the sun. In 1742 Bradley became the third Astronomer Royal. Under his direction the observatory at Greenwich was suppli...
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Americana
Americana term used to describe material printed in or about the Americas, or written by Americans; usually restricted to the formative period in the history of the two continents. Thus the letter written by Columbus in 1493 in which he announces the discovery of the Indies is the earliest item. ...
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Jacobus Cornelius Kapteyn
Jacobus Cornelius Kapteyn , 1851-1922, Dutch astronomer. He was an authority on the Milky Way, of which he made notable statistical studies; he constructed a model of the galaxy known as the "Kapteyn universe." He computed the positions of the stars of the Southern Hemisphere photographed by Sir...
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Andreas Sigismund Marggraf
Andreas Sigismund Marggraf , 1709-82, German chemist, a pioneer in analytical chemistry. He proved that alumina, magnesia, and lime are distinct earths, found (1743) an improved method for the commercial preparation of phosphorus, and isolated (1746) zinc. In 1747 he announced his discovery of sugar...
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Johann von Lamont
Johann von Lamont , 1805-79, Scottish-German astronomer and magnetician, b. Scotland. In 1817 he went to Ratisbon to study at the seminary. He remained in Germany to work in the new observatory at Bogenhausen. Lamont became its director in 1835 and professor of astronomy at the Univ. of Munich in 18...
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Claude Louis Berthollet, Comte
Claude Louis Berthollet, Comte , 1748-1822, French chemist. His contributions to chemistry include the analysis of ammonia and prussic acid and the discovery of the bleaching properties of chlorine. He collaborated with Antoine Lavoisier in his researches and in reforming chemical nomenclature and s...
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William Higgins
William Higgins b. 1762 or 1763, d. 1825, Irish chemist. After study at Oxford he became supervisor of the Royal Dublin Society's mineralogical collection and in 1800 the Society's professor of chemistry. He worked on the chemistry of bleaching and the detection of adulterants in commercial alkalie...
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astatine
astatine [Gr.,=unstable], semimetallic radioactive chemical element; symbol At; at. no. 85; at. wt. of most stable isotope 210; m.p. 302°C (estimated); b.p. 337°C (estimated); density unknown; valence believed to be +1, +3, +5, or +7. Astatine is the heaviest known halogen (Group 17 of th...
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Friedrich Wilhelm Bessel
Friedrich Wilhelm Bessel , 1784-1846, German astronomer and mathematician. He became (1810) director of the new observatory at Königsberg and professor of astronomy at the Univ. of Königsberg. Among his many achievements the most noted is his discovery of the parallax of the fixed star 61 ...
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