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Lindemann, Frederick Alexander

(Encyclopedia)Lindemann, Frederick Alexander (Viscount Cherwell) lĭnˈdəmən, chärˈwĕl [key], 1886–1957, British physicist and government official. He studied with W. H. Nernst and developed with him the Ner...

Lomonosov, Mikhail Vasilyevich

(Encyclopedia)Lomonosov, Mikhail Vasilyevich mēkhəyēlˈ vəsēˈlyəvĭch ləmənôˈsəf [key], 1711–65, Russian scientist, scholar, and writer, an outstanding figure in 18th-century Russia. Lomonosov was the...

thunder

(Encyclopedia)thunder, sound produced along a path of a lightning flash, caused by the rapid heating and expansion of the adjacent air; lightning can heat air to temperatures as much as five times hotter than those...

fire clay

(Encyclopedia)fire clay, clay that has a high degree of resistance to heat. By the best standards it should have a fusion point higher than 1,600℃. The term “fire clay” is commonly held to exclude kaolin and ...

firing

(Encyclopedia)firing, process of treating clay or other plastic ceramic materials with heat to produce a hard, durable but brittle material such as pottery. Primitive potters baked their clay in an open fire, but f...

turquoise

(Encyclopedia)turquoise, hydrous phosphate of aluminum and copper, Al2(OH)3PO4·H2O+Cu, used as a gem. It occurs rarely in crystal form, but is usually cryptocrystalline. Turquoise is opaque and has a waxy luster; ...

Tyndall, John

(Encyclopedia)Tyndall, John tĭnˈdəl [key], 1820–93, British physicist, b. Ireland. He became (1853) professor of natural philosophy at the Royal Institution and in 1867 succeeded Michael Faraday, his friend an...

Vatnajökull

(Encyclopedia)Vatnajökull vätˈnäyöˈko͝ol [key], glacier, c.3,150 sq mi (8,160 sq km), SE Iceland; largest glacier in Europe. At an elevation of from 4,200 to 6,100 ft (1,280–1,860 m), it covers a huge volc...

eczema

(Encyclopedia)eczema ĕkˈsəmə [key], acute or chronic skin disease characterized by redness, itching, serum-filled blisters, crusting, and scaling. Predisposing factors are familial history of allergic disorders...

Haber process

(Encyclopedia)Haber process häˈbər [key], commercial process for the synthesis of ammonia, NH3. Pure hydrogen and nitrogen gases are mixed in the appropriate proportion, heated to between 450℃ and 600℃, comp...