Achromatic condenser

Condenser \Con*dens"er\, n.
   1. One who, or that which, condenses.
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   2. (Physic)
      (a) An instrument for condensing air or other elastic
          fluids, consisting of a cylinder having a movable
          piston to force the air into a receiver, and a valve
          to prevent its escape.
      (b) An instrument for concentrating electricity by the
          effect of induction between conducting plates
          separated by a nonconducting plate.
      (c) A lens or mirror, usually of short focal distance,
          used to concentrate light upon an object.
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   3. (Chem.) An apparatus for receiving and condensing the
      volatile products of distillation to a liquid or solid
      form, by cooling.
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   4. (Steam Engine) An apparatus, separate from the cylinder,
      in which the exhaust steam is condensed by the action of
      cold water or air. See Illust. of {Steam engine}.
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   {Achromatic condenser} (Optics), an achromatic lens used as a
      condenser.

   {Bull's-eye condenser}, or {Bull's-eye} (Optics), a lens of
      short focal distance used for concentrating rays of light.
      

   {Injection condenser}, a vessel in which steam is condensed
      by the direct contact of water.

   {Surface condenser}, an apparatus for condensing steam,
      especially the exhaust of a steam engine, by bringing it
      into contact with metallic surface cooled by water or air.
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