coal tar /ˈkol-/ 名詞



 Tar, n.  A thick, black, viscous liquid obtained by the distillation of wood, coal, etc., and having a varied composition according to the temperature and material employed in obtaining it.
 Coal tar. See in the Vocabulary.
 Mineral tar Min., a kind of soft native bitumen.
 Tar board, a strong quality of millboard made from junk and old tarred rope. --Knight.
 Tar water. (a) A cold infusion of tar in water, used as a medicine. (b) The ammoniacal water of gas works.
 Wood tar, tar obtained from wood. It is usually obtained by the distillation of the wood of the pine, spruce, or fir, and is used in varnishes, cements, and to render ropes, oakum, etc., impervious to water.


 Coal n.
 1. A thoroughly charred, and extinguished or still ignited, fragment from wood or other combustible substance; charcoal.
 2. Min. A black, or brownish black, solid, combustible substance, dug from beds or veins in the earth to be used for fuel, and consisting, like charcoal, mainly of carbon, but more compact, and often affording, when heated, a large amount of volatile matter.
 Note: ☞ This word is often used adjectively, or as the first part of self-explaining compounds; as, coal-black; coal formation; coal scuttle; coal ship. etc.
 Note: ☞ In England the plural coals is used, for the broken mineral coal burned in grates, etc.; as, to put coals on the fire. In the United States the singular in a collective sense is the customary usage; as, a hod of coal.
 Age of coal plants. See Age of Acrogens, under Acrogen.
 Anthracite or Glance coal. See Anthracite.
 Bituminous coal. See under Bituminous.
 Blind coal.  See under Blind.
 Brown coal or Brown Lignite. See Lignite.
 Caking coal, a bituminous coal, which softens and becomes pasty or semi-viscid when heated. On increasing the heat, the volatile products are driven off, and a coherent, grayish black, cellular mass of coke is left.
 Cannel coal, a very compact bituminous coal, of fine texture and dull luster. See Cannel coal.
 Coal bed Geol., a layer or stratum of mineral coal.
 Coal breaker, a structure including machines and machinery adapted for crushing, cleansing, and assorting coal.
 Coal field Geol., a region in which deposits of coal occur. Such regions have often a basinlike structure, and are hence called coal basins. See Basin.
 Coal gas, a variety of carbureted hydrogen, procured from bituminous coal, used in lighting streets, houses, etc., and for cooking and heating.
 Coal heaver, a man employed in carrying coal, and esp. in putting it in, and discharging it from, ships.
 Coal measures. Geol. (a) Strata of coal with the attendant rocks. (b) A subdivision of the carboniferous formation, between the millstone grit below and the Permian formation above, and including nearly all the workable coal beds of the world.
 Coal oil, a general name for mineral oils; petroleum.
 Coal plant Geol., one of the remains or impressions of plants found in the strata of the coal formation.
 Coal tar. See in the Vocabulary.
 To haul over the coals, to call to account; to scold or censure. [Colloq.]
 Wood coal. See Lignite.


 Coal tar A thick, black, tarry liquid, obtained by the distillation of bituminous coal in the manufacture of illuminating gas; used for making printer's ink, black varnish, etc. It is a complex mixture from which many substances have been obtained, especially hydrocarbons of the benzene or aromatic series.
 Note: ☞ Among its important ingredients are benzene, aniline, phenol, naphtalene, anthracene, etc., which are respectively typical of many dye stuffs, as the aniline dyes, the phthaleïns, indigo, alizarin, and many flavoring extracts whose artificial production is a matter of great commercial importance.

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 coal tar
      n : a tar formed from distillation of bituminous coal; coal tar
          can be further distilled to give various aromatic
          compounds