- Torricellian vacuum
- Vacuum Vac"u*um, n.; pl. E. {Vacuums}, L. {Vacua}. [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]
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 glass tube provided with platinum electrodes and exhausted, for the passage of the electrical discharge; a Geissler tube.
{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]
The Collaborative International Dictionary of English. 2000.