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earthquake

(Encyclopedia)CE5 Worldwide pattern of earthquake activity: The dots indicate the epicenters of all earthquakes recorded during a recent 10-year period. CE5 earthquake, trembling or shaking movement of the ea...

glass

(Encyclopedia)glass, hard substance, usually brittle and transparent, composed chiefly of silicates and an alkali fused at high temperature. Glass has become invaluable in modern architecture, illumination, elect...

flerovium

(Encyclopedia)flerovium, artificially produced radioactive chemical element; symbol Fl; at. no. 114; mass number of most stable isotope 289; m.p., b.p., sp. gr., and valence unknown. Situated in Group 14 of the per...

Toussaint Louverture, François Dominique

(Encyclopedia)Toussaint Louverture or L'Ouverture, François Dominique fräNswäˈ dômēnēkˈ to͞osăNˈ lo͞ovĕrtürˈ [key], c.1744–1803, Haitian patriot and martyr. A self-educated slave freed shortly befo...

electron tube

(Encyclopedia)CE5 Triode electron tube electron tube, device consisting of a sealed enclosure in which electrons flow between electrodes separated either by a vacuum (in a vacuum tube) or by an ionized gas at l...

Paleozoic era

(Encyclopedia)Paleozoic era pāˌlēəzōˈĭk [key], a major division (era) of geologic time (see Geologic Timescale, tablegeologic timescale, table) occurring between 570 to 240 million years ago. It is subdivide...

steel

(Encyclopedia)steel, alloy of iron, carbon, and small proportions of other elements. Iron contains impurities in the form of silicon, phosphorus, sulfur, and manganese; steelmaking involves the removal of these imp...

Vérendrye, Pierre Gaultier de Varennes, sieur de la

(Encyclopedia)Vérendrye, Pierre Gaultier de Varennes, sieur de la pyĕr gōtyāˈ də värĕnˈ syör də lä vāräNdrēˈ [key], 1685–1749, explorer in W Canada and the United States, b. Trois Rivières (Three...

nickel

(Encyclopedia)nickel, metallic chemical element; symbol Ni; at. no. 28; at. wt. 58.6934; m.p. about 1,453℃; b.p. about 2,732℃; sp. gr. 8.902 at 25℃; valence 0, +1, +2, +3, or +4. Nickel is a hard, malleable, ...

Brown, John, American abolitionist

(Encyclopedia)Brown, John, 1800–1859, American abolitionist, b. Torrington, Conn. He spent his boyhood in Ohio. Before he became prominent in the 1850s, his life ha...