circulating medium

Medium \Me"di*um\, n.; pl. L. {Media}, {E}. {Mediums}. [L.
   medium the middle, fr. medius middle. See {Mid}, and cf.
   {Medius}.]
   1. That which lies in the middle, or between other things;
      intervening body or quantity. Hence, specifically:
      (a) Middle place or degree; mean.
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                The just medium . . . lies between pride and
                abjection.                        --L'Estrange.
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      (b) (Math.) See {Mean}.
      (c) (Logic) The mean or middle term of a syllogism; that
          by which the extremes are brought into connection.
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   2. A substance through which an effect is transmitted from
      one thing to another; as, air is the common medium of
      sound. Hence: The condition upon which any event or action
      occurs; necessary means of motion or action; that through
      or by which anything is accomplished, conveyed, or carried
      on; specifically, in animal magnetism, spiritualism, etc.,
      a person through whom the action of another being is said
      to be manifested and transmitted.
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            Whether any other liquors, being made mediums, cause
            a diversity of sound from water, it may be tried.
                                                  --Bacon.
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            I must bring together
            All these extremes; and must remove all mediums.
                                                  --Denham.
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   3. An average. [R.]
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            A medium of six years of war, and six years of
            peace.                                --Burke.
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   4. A trade name for printing and writing paper of certain
      sizes. See {Paper}.
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   5. (Paint.) The liquid vehicle with which dry colors are
      ground and prepared for application.
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   6. (Microbiology) A source of nutrients in which a
      microorganism is placed to permit its growth, cause it to
      produce substances, or observe its activity under defined
      conditions; also called {culture medium} or {growth
      medium}. The medium is usually a solution of nutrients in
      water, or a similar solution solidified with gelatin or
      agar.
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   7. A means of transmission of news, advertising, or other
      messages from an information source to the public, also
      called a {news medium}, such as a newspaper or radio; used
      mostly in the plural form, i. e. {news media} or {media}.
      See 1st {media}[2].
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   {Circulating medium}, a current medium of exchange, whether
      coin, bank notes, or government notes.

   {Ethereal medium} (Physics), the ether.

   {Medium of exchange}, that which is used for effecting an
      exchange of commodities -- money or current
      representatives of money.
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Circulate \Cir"cu*late\, v. i. [imp. & p. p. {Circulated}; p.
   pr. & vb. n. {Circulating}.] [L. circulatus, p. p. of
   circulare, v. t., to surround, make round, circulari, v. i.,
   to gather into a circle. See {Circle}.]
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   1. To move in a circle or circuitously; to move round and
      return to the same point; as, the blood circulates in the
      body. --Boyle.
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   2. To pass from place to place, from person to person, or
      from hand to hand; to be diffused; as, money circulates; a
      story circulates.
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   {Circulating decimal}. See {Decimal}.

   {Circulating library}, a library whose books are loaned to
      the public, usually at certain fixed rates.

   {Circulating medium}. See {Medium}.
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