A carbon for arc lamps with a central core of softer carbon than the exterior zone. It fixes the position of the arc, and is supposed to give a steadier light.

For lamps, carbons and battery plates carbons are made by igniting, while protected from the action of the air, a mixture of carbon dust and a cementing and carbonizable substance. Lamp black may be added also. Powdered coke or gas carbon is mixed with molasses, coal tar, syrup, or some similar carbonaceous liquid. It is [...]

(a) One of the elements; atomic weight, 12. It exists in three allotropic modifications, charcoal, graphite and diamond. In the graphitic form it is used as an electric current conductor, as in batteries and for arc lamp, electrodes and incandescent lamp filaments. It is the only substance which conducts electricity and which cannot be melted [...]

The reaction between liquid surfaces of different kinds or between liquid and solid surfaces due to surface tension. Its phenomena are greatly modified by electric charging, which alters the surface tension. Capillarity is the cause of solutions “creeping,” as it is termed. Thus in gravity batteries a crust of zinc sulphate often formed over the [...]

In secondary batteries the quantity of electrical current which they can supply when charged, without undue exhaustion. It is expressed in ampere-hours. The potential varies so little during the discharge that it is assumed to be constant.

The unit of capacity is the capacity of a surface which a unit quantity will raise to a unit potential. The practical unit is the surface which a coulomb will raise to one volt, and is called the farad, q. v.

The ratio of the capacity of a condenser when its plates are separated by any substance to the capacity of the same condenser when its plates are separated by air. A static accumulator consists of two conducting surfaces separated by an insulator. It is found that the capacity of an accumulator for an electric charge, [...]

When two insulated conductors are separated by a dielectric, and are discharged disruptively by being connected or nearly connected electrically, on removing the discharger it is found that a slight charge is present after a short interval. This is the residual charge. Shaking or jarring the dielectric facilitates the complete discharge. This retaining of a [...]

The relative resistance to polarization of a voltaic cell, measured by the quantity of electricity it can supply before polarization. A counter-electromotive force may be developed, or the acid or other solution may become exhausted. The quantity of electricity delivered before this happens depends on the size and type of cell and other factors.

The electric capacity of a telegraphic conductor is identical in quality with that of any other conductor. It varies in quantity, not only for different wires, but for the same wire under different environments, as the wire reacting through the surrounding air or other dielectric upon the earth, represents one element of a condenser, the [...]