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rheostat

(Encyclopedia)rheostat rēˈəstătˌ [key], device whose resistance to electric current depends on the position of some mechanical element or control in the device. Typically a rheostat consists of a resistance el...

Organization for the Prohibition of Chemical Weapons

(Encyclopedia)Organization for the Prohibition of Chemical Weapons (OPCW), international body (est. 1997) responsible for the implementation of the Chemical Weapons Convention (CWC), which aims at the destruction o...

strontium

(Encyclopedia)strontium strŏnˈshēəm [key] [from Strontian, a Scottish town], a metallic chemical element; symbol Sr; at. no. 38; at. wt. 87.62; m.p. 769℃; b.p. 1,384℃; sp. gr. 2.6 at 20℃; valence +2. Stro...

krypton

(Encyclopedia)krypton krĭpˈtŏn [key] [Gr.,=hidden], gaseous chemical element; symbol Kr; at. no. 36; at. wt. 83.798; m.p. −156.6℃; b.p. −152.3℃; density 3.73 grams per liter at STP; valence usually 0. Kr...

symbol

(Encyclopedia)symbol, sign representing something that has an independent existence. The most important use of symbols is in language. To say so, however, does not solve the perennial philosophical questions as to ...

potassium

(Encyclopedia)potassium pətăsˈēəm [key], a metallic chemical element; symbol K [Lat. kalium=alkali]; at. no. 19; at. wt. 39.0983; m.p. 63.25℃; b.p. 760℃; sp. gr. .862 at 20℃; valence +1. Potassium is a s...

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...

Fermi, Enrico

(Encyclopedia)Fermi, Enrico ĕnrēˈkō fĕrˈmē [key], 1901–54, American physicist, b. Italy. He studied at Pisa, Göttingen, and Leiden, and taught physics at the universities of Florence and Rome. He contribu...

rhodium

(Encyclopedia)rhodium rōˈdēəm [key], metallic chemical element; symbol Rh; at. no. 45; at. wt. 102.90550; m.p. about 1,966℃; b.p. 3,727±100℃; sp. gr. 12.41 at 20℃; valence +2, +3, +4, +5, or +6. Rhodium ...

anemia

(Encyclopedia)anemia ənēˈmēə [key], condition in which the concentration of hemoglobin in the circulating blood is below normal. Such a condition is caused by a deficient number of erythrocytes (red blood cell...