oil of vitriol
    n 1: (H2SO4) a highly corrosive acid made from sulfur dioxide;
         widely used in the chemical industry [syn: vitriol, oil
         of vitriol, sulfuric acid, sulphuric acid]

Oil \Oil\ (oil), n. [OE. oile, OF. oile, F. huile, fr. L. oleum;
   akin to Gr. ?. Cf. Olive.]
   Any one of a great variety of unctuous combustible
   substances, more viscous than and not miscible with water;
   as, olive oil, whale oil, rock oil, etc. They are of animal,
   vegetable, or mineral origin and of varied composition, and
   they are variously used for food, for solvents, for
   anointing, lubrication, illumination, etc. By extension, any
   substance of an oily consistency; as, oil of vitriol.
   [1913 Webster]

   Note: The mineral oils are varieties of petroleum. See
         Petroleum. The vegetable oils are of two classes,
         essential oils (see under Essential), and natural
         oils which in general resemble the animal oils and
         fats. Most of the natural oils and the animal oils and
         fats consist of ethereal salts of glycerin, with a
         large number of organic acids, principally stearic,
         oleic, and palmitic, forming respectively stearin,
         olein, and palmitin. Stearin and palmitin prevail in
         the solid oils and fats, and olein in the liquid oils.
         Mutton tallow, beef tallow, and lard are rich in
         stearin, human fat and palm oil in palmitin, and sperm
         and cod-liver oils in olein. In making soaps, the acids
         leave the glycerin and unite with the soda or potash.
         [1913 Webster]

   Animal oil, Bone oil, Dipple's oil, etc. (Old Chem.), a
      complex oil obtained by the distillation of animal
      substances, as bones. See Bone oil, under Bone.

   Drying oils, Essential oils. (Chem.) See under Drying,
      and Essential.

   Ethereal oil of wine, Heavy oil of wine. (Chem.) See
      under Ethereal.

   Fixed oil. (Chem.) See under Fixed.

   Oil bag (Zool.), a bag, cyst, or gland in animals,
      containing oil.

   Oil beetle (Zool.), any beetle of the genus Meloe and
      allied genera. When disturbed they emit from the joints of
      the legs a yellowish oily liquor. Some species possess
      vesicating properties, and are used instead of
      cantharides.

   Oil box, or Oil cellar (Mach.), a fixed box or reservoir,
      for lubricating a bearing; esp., the box for oil beneath
      the journal of a railway-car axle.

   Oil cake. See under Cake.

   Oil cock, a stopcock connected with an oil cup. See Oil
      cup.

   Oil color.
   (a) A paint made by grinding a coloring substance in oil.
   (b) Such paints, taken in a general sense.
   (b) a painting made from such a paint.

   Oil cup, a cup, or small receptacle, connected with a
      bearing as a lubricator, and usually provided with a wick,
      wire, or adjustable valve for regulating the delivery of
      oil.

   Oil engine, a gas engine worked with the explosive vapor of
      petroleum.

   Oil gas, inflammable gas procured from oil, and used for
      lighting streets, houses, etc.

   Oil gland.
   (a) (Zool.) A gland which secretes oil; especially in birds,
       the large gland at the base of the tail.
   (b) (Bot.) A gland, in some plants, producing oil.

   Oil green, a pale yellowish green, like oil.

   Oil of brick, empyreumatic oil obtained by subjecting a
      brick soaked in oil to distillation at a high temperature,
      -- used by lapidaries as a vehicle for the emery by which
      stones and gems are sawn or cut. --Brande & C.

   Oil of talc, a nostrum made of calcined talc, and famous in
      the 17th century as a cosmetic. [Obs.] --B. Jonson.

   Oil of vitriol (Chem.), strong sulphuric acid; -- so called
      from its oily consistency and from its forming the
      vitriols or sulphates.

   Oil of wine, [OE]nanthic ether. See under [OE]nanthic.

   Oil painting.
   (a) The art of painting in oil colors.
   (b) Any kind of painting of which the pigments are originally
       ground in oil.

   Oil palm (Bot.), a palm tree whose fruit furnishes oil,
      esp. Elaeis Guineensis. See Elaeis.

   Oil sardine (Zool.), an East Indian herring (Clupea
      scombrina), valued for its oil.

   Oil shark (Zool.)
   (a) The liver shark.
   (b) The tope.

   Oil still, a still for hydrocarbons, esp. for petroleum.

   Oil test, a test for determining the temperature at which
      petroleum oils give off vapor which is liable to explode.
      

   Oil tree. (Bot.)
   (a) A plant of the genus Ricinus (Ricinus communis), from
       the seeds of which castor oil is obtained.
   (b) An Indian tree, the mahwa. See Mahwa.
   (c) The oil palm.

   To burn the midnight oil, to study or work late at night.
      

   Volatle oils. See Essential oils, under Essential.
      [1913 Webster]

Sulphuric \Sul*phu"ric\, a. [Cf. F. sulfurique.]
   1. Of or pertaining to sulphur; as, a sulphuric smell.
      [1913 Webster]

   2. (Chem.) Derived from, or containing, sulphur;
      specifically, designating those compounds in which the
      element has a higher valence as contrasted with the
      sulphurous compounds; as, sulphuric acid.
      [1913 Webster]

   Sulphuric acid.
      (a) Sulphur trioxide (see under Sulphur); -- formerly so
          called on the dualistic theory of salts. [Obs.]
      (b) A heavy, corrosive, oily liquid, H2SO4, colorless
          when pure, but usually yellowish or brownish, produced
          by the combined action of sulphur dioxide, oxygen
          (from the air), steam, and nitric fumes. It attacks
          and dissolves many metals and other intractable
          substances, sets free most acids from their salts, and
          is used in the manufacture of hydrochloric and nitric
          acids, of soda, of bleaching powders, etc. It is also
          powerful dehydrating agent, having a strong affinity
          for water, and eating and corroding paper, wood,
          clothing, etc. It is thus used in the manufacture of
          ether, of imitation parchment, and of nitroglycerin.
          It is also used in etching iron, in removing iron
          scale from forgings, in petroleum refining, etc., and
          in general its manufacture is the most important and
          fundamental of all the chemical industries. Formerly
          called vitriolic acid, and now popularly vitriol,
          and oil of vitriol.

   Fuming sulphuric acid, or Nordhausen sulphuric acid. See
      Disulphuric acid, under Disulphuric.

   Sulphuric anhydride, sulphur trioxide. See under Sulphur.
      

   Sulphuric ether, common anaesthetic ether; -- so called
      because made by the catalytic action of sulphuric acid on
      alcohol. See Ether, 3
      (a) .
          [1913 Webster]

Vitriol \Vit"ri*ol\, n. [F. vitriol; cf. Pr. vitriol, vetriol,
   Sp. & Pg. vitriolo, It. vitriuolo; fr. L. vitreolus of glass,
   vitreus vitreous. See Vitreous.] (Chem.)
   (a) A sulphate of any one of certain metals, as copper, iron,
       zinc, cobalt. So called on account of the glassy
       appearance or luster.
   (b) Sulphuric acid; -- called also oil of vitriol. So
       called because first made by the distillation of green
       vitriol. See Sulphuric acid, under Sulphuric.
       [Colloq.]
       [1913 Webster]

   Blue vitriol. See under Blue.

   Green vitriol, ferrous sulphate; copperas. See under
      Green.

   Oil of vitriol, sulphuric or vitriolic acid; -- popularly
      so called because it has the consistency of oil.

   Red vitriol, a native sulphate of cobalt.

   Vitriol of Mars, ferric sulphate, a white crystalline
      substance which dissolves in water, forming a red
      solution.

   White vitriol, zinc sulphate, a white crystalline substance
      used in medicine and in dyeing. It is usually obtained by
      dissolving zinc in sulphuric acid, or by roasting and
      oxidizing certain zinc ores. Formerly called also vitriol
      of zinc.
      [1913 Webster]