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superconductivity

(Encyclopedia)superconductivity, abnormally high electrical conductivity of certain substances. The phenomenon was discovered in 1911 by Heike Kamerlingh Onnes, who found that the resistance of mercury dropped sudd...

Whistler, James Abbott McNeill

(Encyclopedia)Whistler, James Abbott McNeill, 1834–1903, American painter, etcher, wit, and eccentric, b. Lowell, Mass. Whistler was dismissed from West Point for insufficient knowledge of chemistry and from the ...

Ruskin, John

(Encyclopedia)Ruskin, John, 1819–1900, English critic and social theorist. During the mid-19th cent. Ruskin was the virtual dictator of artistic opinion in England, but Ruskin's reputation declined after his deat...

sea turtle

(Encyclopedia)sea turtle, name for several species of large marine turtles found in tropical and subtropical oceans. These turtles are modified for life in the ocean by having flipperlike forelimbs without toes and...

semiconductor

(Encyclopedia)CE5 N-type and P-type crystals: In a pure silicon crystal each silicon atom (Si) is surrounded by four valence electrons. In the N-doped semiconductor, illustrated in the left-hand figure, some sil...

progressive education

(Encyclopedia)progressive education, movement in American education. Confined to a period between the late 19th and mid-20th cent., the term “progressive education” is generally used to refer only to those educ...

manganese

(Encyclopedia)manganese măngˈgənēs, mănˈ– [key] [Lat.,=magnet], metallic chemical element; symbol Mn; at. no. 25; at. wt. 54.93805; m.p. about 1,244℃; b.p. about 1,962℃; sp. gr. 7.2 to 7.45, depending o...

marsupial

(Encyclopedia)marsupial märso͞oˈpēəl [key], member of the order Marsupialia, or pouched mammals. With the exception of the New World opossums and an obscure S American family (Caenolestidae), marsupials are no...

Wilde, Oscar

(Encyclopedia)Wilde, Oscar (Oscar Fingal O'Flahertie Wills Wilde), 1854–1900, Irish author and wit, b. Dublin. He is most famous for his sophisticated, brilliantly witty plays, which were the first since the come...

walnut

(Encyclopedia)CE5 Black walnut, Juglans nigra walnut, common name for some members of the Juglandaceae, a family of chiefly deciduous, resinous trees characterized by large and aromatic compound leaves. Species...