Columbia Encyclopedia

Search results

186 results found

global warming

(Encyclopedia)global warming, the gradual increase of the temperature of the earth's lower atmosphere as a result of the increase in greenhouse gases since the Industrial Revolution. Global warming and its effects,...

zirconium

(Encyclopedia)zirconium zərkōˈnēəm [key], metallic chemical element; symbol Zr; at. no. 40; at. wt. 91.224; m.p. about 1,852℃; b.p. 4,377℃; sp. gr. 6.5 at 20℃; valence +2, +3, or +4. Zirconium is a very ...

hardpan

(Encyclopedia)hardpan, condition of the soil or subsoil in which the soil grains become cemented together by such bonding agents as iron oxide and calcium carbonate, forming a hard, impervious mass. It is disadvant...

Gogebic

(Encyclopedia)Gogebic gōgēˈbĭk [key], east-west mountain range, 80 mi (129 km) long and .5 to 1 mi (.8–1.6 km) wide, extending from the W Upper Peninsula, N Mich., into N Wis. It is known for its iron deposit...

spinel

(Encyclopedia)spinel, magnesium aluminum oxide, MgAl2O4, a mineral crystallizing in the isometric system, usually as octahedrons. It occurs as an accessory mineral in basic igneous rocks, in aluminum-rich metamorph...

limestone

(Encyclopedia)limestone, sedimentary rock wholly or in large part composed of calcium carbonate. It is ordinarily white but may be colored by impurities, iron oxide making it brown, yellow, or red and carbon making...

thallium

(Encyclopedia)thallium thălˈēəm [key], metallic chemical element; symbol Tl; at. no. 81; interval in which at. wt. ranges 204.382–204.385; m.p. 303.5℃; b.p. about 1,457℃; sp. gr. 11.85 at 20℃; valence +...

mercury, chemical element

(Encyclopedia)mercury or quicksilver [from the Roman god Mercury], metallic chemical element; symbol Hg [Lat. hydrargyrum=liquid silver]; at. no. 80; at. wt. 200.59; m.p. −38.842℃; b.p. 356.58℃; sp. gr. 13.55...

dysprosium

(Encyclopedia)dysprosium dĭsprōˈzēəm [key] [Gr.,=hard to get at], metallic chemical element; symbol Dy; at. no. 66; at. wt. 162.500; m.p. 1,412℃; b.p. 2,562℃; sp. gr. 8.54 at 25℃; valence+3. Dysprosium i...

cupric sulfate

(Encyclopedia)cupric sulfate ko͞oˈprĭk sŭlˈfāt, kyo͞oˈ– [key] or copper (II) sulfate, chemical compound, CuSO4, taking the form of white rhombohedral crystals or amorphous powder. It decomposes at 650℃ ...