A standard of illuminating power; in it the combustible substance is a gas made by mixing one cubic foot of air with three cubic inches of liquid pentane, measured at 60° F. or, if measured as gases, 20 volumes of air to 7 of pentane. It is burned at the rate of 0.5 cubic foot [...]

A stylus for producing a series of perforations in paper, so that the paper may act as a stencil for the reproduction of a great number of copies of the original matter. Various kinds of electric pens have been invented. One kind, invented by Edison, consists of a handle carrying an electric motor actuating a [...]

(a) A pendulum operated by the intermittent action of an electro-magnet, whose circuit is opened and closed by the pendulum itself. A point at the lower end of the pendulum swinging through a globule of mercury may close and open the circuit. Various other methods of accomplishing the same end are employed .. (b) A [...]

A double conductor or pair of conductors, insulated from each other and covered with a worsted, silk, or cotton covering and used to suspend incandescent lamps and at the same time to conduct the current to them. It is also used for other similar service, such as acting as conductors for small motors. Often each [...]

A bar of bismuth and a bar of antimony soldered centre to centre at right angles, being notched or halved there to receive or to set into each other. It is used to demonstrate the Peltier effect, q. v. To one pair of ends are connected the terminals of a battery circuit; to the other [...]

The thermal effect produced by the passage of a current through the junction of two unlike conductors. Such junction is generally the seat of thermo-electric effects, and a current is generally produced by heating such a junction. If an independent current is passed in the same direction as that of the thermoelectric current, it cools [...]

Abbreviation for potential difference or difference of potential, or for electro-motive force.

A state of a substance in virtue of which it is unattacked by a solvent which ordinarily would dissolve or attack it. Iron in strong nitric acid is unattacked or assumes the passive state. This particular case is supposed to be due to a coating of magnetic oxide, so that there would be properly speaking [...]

A fault in a conductor caused by imperfect connection with the earth, where insulation from the earth is desired.

If cellulose is treated with a mixture of two parts of sulphuric acid and one part of water perfectly cold, it becomes like parchment. It should at once be washed with water, and then with ammonia and water. The Swan incandescent light fibres are made of parchmentized cotton thread, which is afterward carbonized.