V
Vacuum. A space empty or void of all matter; a space from which all gases have been exhausted.
Vacuum Tubes. Tubes of glass through which electric discharges are passed after the gases have been partially removed; for example, the X-ray tube of Röntgen and the Crooke tubes.
Vibrator, Electro-magnetic. The make-and-break mechanism used on induction-coils, or other similar apparatus, in which, through alternate attractions, an arm or spring is kept in motion.
Vitriol, Blue. A trade name for copper sulphate. (Bluestone.)
Vitriol, Green. A trade name for ferrous sulphate. (Copperas.)
Vitriol, White. A trade name for zinc sulphate. (Salts of zinc.)
Volt. The practical unit of electro-motive force; the volume and pressure of an electric current.
Voltage. Electric-motive force expressed in volts—as, a voltage of 100 volts.
Voltaic. A term derived from the name of the Italian scientist Volta, and used in many ways as applied to electrical current and devices. Formerly the term galvanic was commonly employed.
Voltaic Electricity. (See [Electricity, Voltaic].)
Voltimeter. An instrument for measuring the voltage of a current.
Vulcanite. Vulcanized rubber. Valuable for its insulating properties and inductive capability.