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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...

epoxy group

(Encyclopedia)epoxy group ĕpˈŏksē [key], in chemistry, functional group that consists of an oxygen atom joined by single bonds to two adjacent carbon atoms, thus forming the three-membered epoxide ring. It is t...

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...