Battery

in Hectricity, is a cell or combina- tion of celts, composed of such constituents and arranged in such a way as will give us an electric current when a conductor is made to join its terminals. The energy required to effect this is supplied by the constituents of the battery, which have a chemical affinity for each other, and by their reaction to produce chemical compounds set free a surplus of energy. If this reaction takes place 399 when surplus circuit to is through is force In readily on have ing sulphuric solve of unle effected and with ag begins in on moreover, understand rent on calculated which ventional copper direction through important cell [VoLT], Leclanché’s duty constancy. copper setting to as primary condition direction current certain the is electric fore convenient be Sagres ic ELECTRICITY, PLANOHE especially fences Floating Battery. ( 369 there is no complete electric circuit, the energy appears as heat; if, however, the is complete, or closed, this energy is directed drive electricity through the circuit. A battery the more effective if it can send a greater current the same resistances. [RESISTANCE.] It then said to S$ a greater electro-motive (q.v.), for brevity generally termed E.M.F. Batteries are of two kinds, primary and secondary. the primary battery we choose materials that are obtainable in the required condition to react one another. Thus, in the simple Volta cell we gv. stick of zinc dipping into a ve el contain dilute sulphuric acid. Zinc has an affinity for acid, and when impure will readily dis there in without the use of a separate piece other metal. If pure the zinc will not di olve a conducting circuit be formed. This is by placing a stick of copper in the liquid, by joining the two metals outside the cell wire or some other conductor. In this case, soon as the circuit is closed the zinc stick to waste away, zinc sulphate is formed the acid solution, and hydrogen bubbles appear the copper stick that dips into the liquid; the circuit acquires properties that we to be due to the flow of an electric cur through it. The E.M.F. of the battery depends the substances used, and may be approximately with a knowledge of the energy with the two poles become oxidised. It is conto regard the current as flowing from to zinc in the outside circuit, which is the of the apparent pa age of the hydrogen the liquid. Descriptions of the more batteries are given separately. Grove’s is useful for its hig EMY, about 1:9 volts its fair constancy and low resistance; for its applicability to intermittent easy; and Latimer Clark’s Standard cell for its The deposition of hydrogen on the pole diminishes the efficacy of the battery by up a counter E.M.F. The means adopted remedy this are discu ed under POLARISATION, this deposition is termed. See batteries do not differ intrinsically from batteries. They are simply brought to the of being able to drive a current in one by the previous pa age of a suitable in the reverse direction. This effects changes in the materials of the battery at expense of electrical energy; which, however, recovered’ when the battery reproduces an current. A secondary battery may there be regarded as an arrangement for the storage of electrical energy, which may taken out when desired. It is extremely practically, on account of its high.F., its very low resistance, and its portability. ELECTRIC LIGHTING, RESISTANCE, CELL.] Ba, FLOATING. A floating fort, designed for the purpose of attacking land deand only secondarily as a mobile man-of-war. batteries were first used on a large scale 2340—N.B, ) Battlement. biol by the Spaniards during their grand attack on Gibraltar in 1782, On that occasion ten elaborately contrived batteries were used, their sides being of immense thickne and solidity, and their upper decks covered with turf: but the British red hot shot burnt and blew up nine out of the ten, and the remaining one was boarded and set on fire. During the Ru ian war of 1854-56 the British Government built eight floating batteries, each carrying fourteen or sixteen guns, with a view to reducing the Sebastopol defences. These were plated with iron, and some were built of iron and some of wood. These were the first ironclads of the British navy, and were modelled after five somewhat similar ve els which were built in France for the same object, but all of wood. The speed of these ve els was inconsiderable, and in no case exceeded about six miles an hour. They were completed too late to be of much use during the war.