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Grew, Nehemiah

(Encyclopedia)Grew, Nehemiah, 1641–1712, English botanist and physician. Grew practiced medicine in London and made important microscopic studies of plants. He made what were probably the first observations of se...

Gerhardt, Charles Frédéric

(Encyclopedia)Gerhardt, Charles Frédéric shärl frādārēkˈ zhārärˈ [key], 1816–56, French chemist, b. Strasbourg. He revived the theory of acid radicals, which he called the theory of residues, and did va...

K

(Encyclopedia)K, 11th letter of the alphabet. It is a usual symbol for a voiceless velar stop, as in the English cook. It corresponds to Greek kappa. In chemistry K is the symbol for the element potassium. ...

Wittig, Georg

(Encyclopedia)Wittig, Georg, 1897–1987, German chemist, Ph.D. Univ. of Marburg, 1926. During his career, Wittig was a professor at the universities of Braunschweig, Freiburg, Tübingen, and Heidelberg. He shared ...

Covington

(Encyclopedia)Covington kŭvˈĭngtən [key], city (2020 pop. 40,181), seat of Kenton co., N central Ky., at the ...

Mitchell, William

(Encyclopedia)Mitchell, William (Billy Mitchell), 1879–1936, American army officer and pilot, b. Nice, France. He enlisted (1898) in the U.S. army in the Spanish-American War and received a commission in the regu...

Tagus

(Encyclopedia)Tagus tāˈgəs [key], Span. Tajo, Port. Tejo, river, c.585 mi (940 km) long, rising in the mountains E of Madrid, E Spain, and draining the central part of the Iberian Peninsula. The Tagus flows nort...

atomic mass unit

(Encyclopedia)atomic mass unit or amu, in chemistry and physics, unit defined as exactly 1⁄12 the mass of an atom of carbon-12, the isotope of carbon with six protons and six neutrons in its nucleus. One amu is e...

Poggendorff, Johann Christian

(Encyclopedia)Poggendorff, Johann Christian yōˈhän krĭsˈtyän pôgˈəndôrfˌ [key], 1796–1877, German physicist and chemist. He founded (1824) and edited the important Annalen der Physik und Chemie and edi...

Pregl, Fritz

(Encyclopedia)Pregl, Fritz frĭts prāˈgəl [key], 1869–1930, Austrian physiologist and chemist, M.D. Univ. of Graz, 1894. He taught at the universities of Innsbruck (1910–13) and Graz (from 1913). For his met...