Density, Electric Superficial.
The relative quantity of electricity residing as an electric charge upon
a unit area of surface. It may be positive or negative.
Synonyms--Density of Charge--Surface Density.
Dental Mallet, Electric.
A dentist's instrument for hammering the fillings as inserted into
teeth. It is a little hammer held in a suitable handle, and which is
made to strike a rapid succession of blows by electro-magnetic motor
mechanism.
Depolarization.
(a) The removal of permanent magnetism. (See Demagnetization.)
(b) The prevention of the polarization of a galvanic cell. It is
effected in the Grove battery by the reduction of nitric acid; in the
Bunsen, by the reduction of chromic acid; in the Smee battery,
mechanically, by the platinum coated or rather platinized negative
plate. Other examples will be found under the description of various
cells and batteries. A fluid which depolarizes is termed a depolarizer
or depolarizing fluid or solution. (See Electropoion Fluid.)
Deposit, Electrolytic.
The metal or other substance precipitated by the action of a battery or
other current generator.
Derivation, Point of.
A point where a circuit branches or divides into two or more leads. The
separate branches then receive derived or partial currents.
Desk Push.
A press or push button, with small flush rim, for setting into the
woodwork of a desk.
Detector.
A portable galvanometer, often of simple construction, used for rough or
approximate work.
Detector, Lineman's.
A portable galvanometer with a high and a low resistance actuating coil,
constructed for the use of linemen and telegraph constructors when in
the field, and actually putting up, repairing or testing lines.
Deviation, Quadrantal.
Deviation of the compass in iron or steel ships due to the magnetization
of horizontal beams by the earth's induction. The effect of this
deviation disappears when the ship is in the plane of the electric
meridian, or at right angles thereto; its name is taken from the fact
that a swing of the ship through a quadrant brings the needle from zero
deviation to a maximum and back to zero.