Electric Battery

(1) Primary or voltaic: Two di imilar substances, or metallic surfaces, both ‘conductors of electricity, immersed in a jar of acidulated water or other exciting fluid, that will act more energetically on one than on the other, the two conductors being connected on the outside by a wire; the substance or surface le acted upon is the negative, and that more acted upon the positive pole, the current fperiipeftom the positive to_the negative. he electrodes, or — poles, are most commonly made of caron or zinc; platinum, gold, silver, copper, iron, tin, and lead, may be, but are not used, because of cost or high resistance of the metals. The common excitants are sulphuric or nitric acid, bicarbonate of potash, sulphate of copper solution, or sal ammoniac solution. (2) Secondary or storage; alse called accumulator: A series of metallic or other conducting plates, usually lead, divided from each other by a non-conducting substance, the whole being immersed in a water solution; through this solution a primary current is sent from the negative to the positive, decomposing the water, its oxygen forming with the lead on the evi pole a peroxide of lead, and leaving a deposit of metallic lead on -the negative plate, the oxide then _being destroyed by the hydrogen. When the primary discharge from the negative to the Pinay pole is stopped, the chemical affinity of the oxygen in the peroxide of lead for the metallic lead causes it to leave the positive for the negative pole, thereby causing a current from the positive to the negative pole, which is utilized as a primary current, Electric Bell. (1) Magnetic or dynamic; two electro-magnets, parallel and in series, having at their extremity a vibrating armature in close proximity pivoted between them; fixed to this armature is a clapper vibrating between two,.gongs. The current pa es through the fields, magnetizing the cores, and in generating an alternating current vibrates the armature and rings the bell. (2) Battery-bell: A single coil or bobbin of wire, wound around an iron eore; a vibratory armature, pivoted at one end, and pa ing at a right angle by the eore of the bobbin; at the other end of the armature is a clapper, a gong situated close to the clapper. A delicate spring is attached to the vibratory armature near the clapper, which, while the current is pa ing, operates against a set-screw placed for the purpose. The current pa ing through the bobbin to the set-screw magnetizing the core, attracts the armature which in turn is repelled, the spring working against the screw. These alternate attractions and repulsions of the armature vibrate the clapper and ring the bell.