Vacuums

1 definition found

From The Collaborative International Dictionary of English v.0.48 [gcide]:

  Vacuum \Vac"u*um\ (v[a^]k"[-u]*[u^]m), n.; pl. E. {Vacuums}
     (v[a^]k"[-u]*[u^]mz), L. {Vacua} (v[a^]k"[-u]*[.a]). [L., fr.
     vacuus empty. See {Vacuous}.]
     1. (Physics) A space entirely devoid of matter (called also,
        by way of distinction, absolute vacuum); hence, in a more
        general sense, a space, as the interior of a closed


        vessel, which has been exhausted to a high or the highest
        degree by an air pump or other artificial means; as, water
        boils at a reduced temperature in a vacuum.
        [1913 Webster]
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     2. The condition of rarefaction, or reduction of pressure
        below that of the atmosphere, in a vessel, as the
        condenser of a steam engine, which is nearly exhausted of
        air or steam, etc.; as, a vacuum of 26 inches of mercury,
        or 13 pounds per square inch.
        [1913 Webster]
  
     {Vacuum brake}, a kind of continuous brake operated by
        exhausting the air from some appliance under each car, and
        so causing the pressure of the atmosphere to apply the
        brakes.
  
     {Vacuum pan} (Technol.), a kind of large closed metallic
        retort used in sugar making for boiling down sirup. It is
        so connected with an exhausting apparatus that a partial
        vacuum is formed within. This allows the evaporation and
        concentration to take place at a lower atmospheric
        pressure and hence also at a lower temperature, which
        largely obviates the danger of burning the sugar, and
        shortens the process.
  
     {Vacuum pump}. Same as {Pulsometer}, 1.
  
     {Vacuum tube} (Phys.),
        (a) a glass tube provided with platinum electrodes and
            exhausted, for the passage of the electrical
            discharge; a Geissler tube.
        (a) any tube used in electronic devices, containing a
            vacuum and used to control the flow of electrons in a
            circuit, as a vacuum diode, triode, tetrode, or
            pentode.
  
     {Vacuum valve}, a safety valve opening inward to admit air to
        a vessel in which the pressure is less than that of the
        atmosphere, in order to prevent collapse.
  
     {Torricellian vacuum}. See under {Torricellian}.
        [1913 Webster]