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sapphire

(Encyclopedia)sapphire, precious stone. A transparent blue corundum, it is classified among the most valuable of gems. Sapphires are found chiefly in Madagascar, Sri Lanka, and Myanmar and also in Thailand, Tanzani...

Ignarro, Louis Joseph

(Encyclopedia)Ignarro, Louis Joseph, 1941–. American pharmacologist, b. Brooklyn, N.Y., Ph.D. Univ. of Minnesota, 1966. He was on the faculty at Tulane Univ. from 1979 to 1985, when he became a professor at the U...

holmium

(Encyclopedia)holmium hōlˈmēəm [key] [Lat.,=Stockholm], metallic chemical element; symbol Ho; at. no. 67; at. wt. 164.93032; m.p. about 1,474℃; b.p. about 2,425℃; sp. gr. 8.78 at 25℃; valence +3. Holmium ...

lanthanum

(Encyclopedia)lanthanum lănˈthənəm [key] [Gr.,=to lie hidden], metallic chemical element; symbol La; at. no. 57; at. wt. 138.90547; m.p. about 920℃; b.p. about 3,460℃; sp. gr. 6.19 at 25℃; valence +3. Lan...

sandpaper

(Encyclopedia)sandpaper, abrasive originally made by gluing grains of sand to heavy paper sheets. Today sandpaper is made primarily with quartz, aluminum oxide, or silicon carbide grains, and is graded according to...

molybdenum

(Encyclopedia)molybdenum məlĭbˈdənəm [key] [Gr.,=leadlike], metallic chemical element; symbol Mo; at. no. 42; at. wt. 95.96; m.p. about 2,617℃; b.p. about 4,612℃; sp. gr. 10.22 at 20℃; valence +2, +3, +4...

Great Grimsby

(Encyclopedia)Great Grimsby or Grimsby, city, North East Lincolnshire, E central England, at the mouth of the Humber River. It is one of the largest fishing ports...

Port Radium

(Encyclopedia)Port Radium, mining village, N central Northwest Territories, Canada, on Great Bear Lake. The mines were discovered in 1930 and yielded deposits of pitchblende, from which much radium was produced. Du...

soman

(Encyclopedia)soman, colorless liquid used as a nerve gas. It boils at 167℃, evolving an odorless vapor. It is rapidly absorbed through the skin; death may result within 15 min of exposure. In nonfatal concentrat...

white lead

(Encyclopedia)white lead, heavy, white substance, poisonous, insoluble in water, extensively used as a white pigment and base in paints. It is one of the oldest paint pigments used by humans. Chemically, it is basi...