Decomposition. The separation of a liquid, such as an electrolyte, into its prime elements, either electrically or otherwise. Deflection. The change of movement of a magnetic needle out of its regular direction of movement. Demagnetization. When a current passes through a coil wound on an iron core, the core becomes magnetized. When the current ceases the core is no longer a magnet. It is then said to be _demagnetized_. It also has reference to the process for making a watch non-magnetic so that it will not be affected when in a magnetic field. Density. The quantity of an electric charge in a conductor or substance. Depolarization. The removal of magnetism from a permanent magnet, or a horse-shoe magnet, for instance. It is generally accomplished by applying heat. Deposition, The act of carrying metal from one pole of a cell to Electrolysis. another pole, as in electroplating. Detector. Mechanism for indicating the presence of a current in a circuit. Diaphragm. A plate in a telephone, which, in the receiver, is in the magnetic field of a magnet, and in a transmitter carries the light contact points. Dielectric. A non-conductor for an electric current, but through which electro-static induction will take place. For example: glass and rubber are dielectrics. Discharge. The current flowing from an accumulator. Disintegration. The breaking up of the plate or active material. Disruptive. A static discharge passing through a dielectric. Duplex Wire. A pair of wires usually twisted together and insulated from each other to form the conducting circuit of a system. Dynamic Electricity. The term applied to a current flowing through a wire. Dynamo. An apparatus, consisting of core and field magnets, which, when the core is turned, will develop a current of electricity. Earth Returns. Instead of using two wires to carry a circuit, the earth is used for what is called the _return_ circuit. Efficiency. The total electrical energy produced, in which that wasted, as well as that used, is calculated. Elasticity. That property of any matter which, after a stress, will cause the substance to return to its original form or condition. Electricity has elasticity, which is utilized in condensers, as an instance.