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gem, ornamental mineral or organic substance

(Encyclopedia)gem, commonly, a mineral or organic substance, cut and polished and used as an ornament. Gems also are used as seals (items of assurance) and as talismans (good-luck charms). For birthstones, see mont...

hydrogen

(Encyclopedia)hydrogen hīˈdrəjən [key] [Gr.,=water forming], gaseous chemical element; symbol H; at. no. 1; interval in which at. wt. ranges 1.00784–1.00811; m.p. −259.14℃; b.p. −252.87℃; density 0.08...

Land, Edwin Herbert

(Encyclopedia)Land, Edwin Herbert, 1909–91, American inventor and photographic pioneer. While at Harvard, Land became interested in the properties and manipulation of polarized light. He left Harvard and, in 1932...

Levi, Primo

(Encyclopedia)Levi, Primo prēˈmō lāˈvē [key], 1919–87, Italian writer. A chemist of Jewish descent, Levi was sent to the concentration camp at Auschwitz during World War II. His first memoir, If This Is a M...

mandrake

(Encyclopedia)mandrake, plant of the family Solanaceae (nightshade family), the source of a narcotic much used during the Middle Ages as a pain-killer and perhaps the subject of more superstition than any other pla...

iceboating

(Encyclopedia)iceboating, sport of sailing a specially prepared boat equipped with runners over ice. The first iceboats were probably sailed by the Dutch during the 18th cent., although the Finns and Sami (Lapps) m...

roentgenium

(Encyclopedia)roentgenium, artificially produced radioactive chemical element; symbol Rg; at. no. 111; mass number of most stable isotope 280; m.p., b.p., sp. gr., and valence unknown. Situated in Group 11 of the p...

Barton, Derek H. R.

(Encyclopedia)Barton, Derek H. R., 1918–98, British chemist, b. Gravesend, England, grad. Imperial College of Science and Technology (B.S. 1940, Ph.D. 1942, D.Sc. 1949). He was on the faculty of Imperial College ...

physical chemistry

(Encyclopedia)physical chemistry, branch of science that combines the principles and methods of physics and chemistry. It provides a fundamental theoretical and experimental basis for all of chemistry, including or...

Randall, Lisa

(Encyclopedia)Randall, Lisa, 1962–, American theoretical physicist and writer, b. New York City, B.A. Harvard University, 1983, Ph.D. Harvard University, 1987. Rand...