Mechanical The electric motor is a secondary and not a primary source of power, that is, it does not convert the stores of energy found in nature into mechanical energy as the steam engine, but mechanical power has to be exerted somewhere to produce the electric power which is reconverted into mechanical power in the electric motor. The advantage of the electric motor is that the mechanical power can be utilized at a distance from the source of power; the factories and mills may be located far distant from the water power and the railroad train or street car receive the power from the distant station. The power generated at one place can be distributed efficiently to a large number of places, or all motors of the city may receive their power from one central generating station. Instead of an extended and mefficient system of belting, individual motors may drive the machines of the factory or mill. All the cars or trains of a railway system may receive their power from one generating system, perhaps a water-power as Niagara. The elec tric motor is under more perfect control than almost any other motor, and when not used consumes no power and requires no special care in starting and operation. 'Mechanical power in small quantities can be produced almost as ef ficiently as in large units and a great subdivision of power becomes thereby feasible. In the field of mechanical power generated by electricity also belong telegraphy and telephony, or the transmission of signals and speech over long distances.
For lighting, electric energy usually is first converted into heat and the light given by the incandescence of very refractory solid substances, carbon or tungsten (wolf ram), the tungsten wire or carbon filament of the in candescent lamp, or the glowing tip or crater of the arc lamp carbons. (See LIGHT ING). Here again, especially with incandescent lamps, the main advantage lies in the absolute steadiness, control and flexibility of the light, the simplicity of turning it on or off, and its relatively high efficiency, which gives a light with less heat than the gas flame or kerosene lamp. While due to the use of heat as inter mediary form of energy only a very few per cent of the electric energy are converted into light, most being dissipated as heat, with the gas or kerosene flame the percentage of energy con verted into light is still much less. Recently considerable work is being done and with great promise of converting electric energy more directly into light by electro-luminescence in luminous arcs, which promise an efficiency of light production very much greater than the incandescent or carbon arc lamp, and there is a possibility of still very much higher efficien cies of light production by electro fluorescence.
conversion of electric energy into heat means a degradation of energy from regular to irregular motion and in the heat production by electric energy only a very few per cent of the heat energy expended under the boilers of the steam engine driving the electric generator is recovered, so that electric heating is usually more expensive than direct generation of heat by combustion and therefore commercially practicable only: 1. For the production of temneratures be yond those which can be reached by combus tion. At very high temperatures chemical affin ity and therefore combustion ceases and tem peratures beyond this cannot be reached by combustion but are reached by conversion of electric energy into heat in the electric fur nace. By this means chemical compounds have been produced for industrial purposes which were either entirely unknown or mere curiosi ties before, as the carbides, calcium carbide, car borundum, silicon metal, etc.
2. Electric energy is used for heating where the temperature has to be perfectly controlled.
3. For intermittent use, such as flat-irons, etc., where heat production by combustion is in efficient.
4. Due to its convenience and cleanliness for domestic uses to a limited extent, electric heating and cooking are coming into use.
Chemical Electric energy is con verted into chemical energy either directly in the electrolytic cell or indirectly with heat as in termediary in the electric furnace as discussed above. Electrolysis (q.v.), that is, the chemical action of electric energy, is used exclusively for the production of aluminum, magnesium, cal cium, etc., metal, is used for copper refining, production of sodium, chlorates, soda and bleaching powder, and many other compounds.
Storage.— Electric energy cannot be stored as such conveniently, but the ease and efficiency of conversion of electric energy into the chem ical energy of metals and metallic oxides, and inversely, permits the storage of electric energy as chemical energy in the storage battery. (See