THE STORAGE OF ELECTRICITY.

Otago Daily Times, Issue 5247, 18 February 1882, Page 2 (Supplement)

THE STORAGE OF ELECTRICITY.

(Times, November 24th.) This was the subject of the lecture last evening at the Society of Arts, the lecturer being Professor Sylvanus Thompson, of BristoL Professor Adams presided, and tho room, which was crowded, was lighted during the ecture by two groups of suspended Edison lamps connected with 40 Faure cells brought to the building ready charged. Professor Thompson began by saying that science had of late made two advances, tho ultimate importance of which it would be difficult to overestimate. One was that the Gramme machine is reversible, and tho other that a voltaic battery is reversible. The latter was the counterpart and complement of the former, for while the one had solved the problem of the electric transmission of power, the other had solved the problem of the electric storage of energy. The electric storage of energy must not be mistaken for the storage of electricity itself. In electric accumulators the kind, of work done was as much chemical as electrical. Before dealing with the various systems of electric storage that have been suggested, he laid down two important o-eneral principles in the following terms :—" First, that no kind of storage of energy, mechanical or electrical, is possible except by doing work in overcoming.some force which itself opposes the process. Secondly, that the action in which the work is thus done must be one lat is reversible—that is to say, to which there is an equal and opposite reaction." He then explained electrical action and reaction. As understood in the light of modem dynamics, any action in which energy is spent and work done is found to have its corresponding reaction in the possibility of the energy thus stored being' at some later time set free. A pound of iron raised at a certain height may, by its fall, raise another pound tc the same height. In electricity and magnetism the same fundamental principle holds good. A heavy weight descending over a pulley causing the disc of a Holtz's machine to rotate would expend energy in moving electricity against those electric foroes which are continually urging it to run down to the deadleve] of equality; and the supply of electricity thus provided can be allowed to run down and give out the energy expended upon it. The reaction would be equal to the action but for the friction and dissipation of the charges. Another illustration was afforded by the'reversibility of dynamo-electric machines whidi could be used as generators or as motors. Electric currents could be set to drive a Gramme machine, and by means of a pulley it mi^ht gradually wind up a heavy weight. Then ii le weight were allowed to descend and drive ;ne Gramme, machine, electric currents would be generated. In the ordinary voltaic cells currents are produced by the consumption oi zinc and of acid, copper being deposited. Reverse the process, drive currents back through the cell, and copper will be dissolved and zinc deposited. The. voltaic battery was a real reversible engine, and it was possible to pumr back the, electric currents into the cell, and tc jump into its metallic state the zinc which had )eon consumed as fuel. While currents were being used to separate the zinc from its solution, that was all the while tending to re-unite Thi< tendency was known as polarisation, which meant the electric reaction at the poles of a cell. It was m overcoming this polarisatior force that the work bf storage was done. Without reaction, storage of energy would be impossible. In treating of the laws of polarisation, he said the work done in separating gases was equal to the work they would do by rushing together. It was possible to calculate the amount of force that would have to be applied to tear away any substance from its combination with oxygen, and a table was given which showed the value of the force which measurec electrically the chemical affinity of certaii elements for oxygen. It showed the order o the oxidisability of metils and the order it which they stood in their power to replace oni another So far, oxygen has been taken as tin standard electro- negative; but peroxides, whet combined with a metal such as zinc, woulc give out a larger amount of heat than zinc die with oxygen, and therefore there was a greate store of energy in the peroxides. Cells shoule .be charged with only just sufficient electro motive force to overcome their reaction, other wise part of the work dons would be wasted ii local heat, and heat diminishes the force of thi cells that are being charged. If the current bi weak and the electrodes large, the polarisatioi never reaches its maximum. The state of thi surface of the electrodes has much to do ii determining the state in which the gases an liberated and the resulting polarisation force After describing and comparing the accumula tors of Plante, De Meritens, and Faure thi lecturer said that Faure'a cells had done gooc work in providing an efficient means of work ing incandescent lamps ; and the lamps o bwann, Maxim, and Edison, lighted by these means, were referred to in illustration. Ar historical summary of the various stages in the invention and perfection of the accumulators or storage batteries, was followed by some anticipations of possible use! First, in regard to lighting, secondary batteries would serve fo; portable supplies of electricity, for accumulated supplies, and for equalisers of electric currents. The value of accumulation was evident m the ease of a theatre whiol might by accident be plunged in (foi-k ness, if dependent on external souTces A possiblo application was tho firing o torpedoes and blasts in mines. Another wa= the perfection of the telephone in increasing the power of the transmitter by employing a mul tiple microphone. A hundred microphones united would produce loud aad distinct speech. By far tho most important of all the possibilities opened out by the storage battery was the utilisation of wmd and. water power. Differing feom Sir W ; Thompson in his address to the British Association, he believed there were cases where no great expense would be incurred illi utilising tidal areas as basins. The Avon at Bristol required but a few yards of embankment to. be turned into such an area, A tenth part of the tidal energy in the gorge of the Avon would light Bristol. A tenth part of the tidal energy in the channel of the Severn would light every city and turn every loom, spindle, and axle in Great Britain. The power would have to be not only transformed and transmitted, but also stored, and therefore accumulators were necessary to utilise tho intermittent forces of the tides. Accumulators themselves might still be greatly improved and the limits of their application enlarged; but even now there were immense possibilities in store. Electrical railways and electrical tramways are now existing facts. Many months will not elapse— or it will be an eternal disgrace to the first city in the world—before the foetid and poisonous atmosphere of the Metropolitan railway is replaced by a pleasant and salubrious air, rich in. fragrant ozone; and the like revolution will not be long delayed in many quarters where reform is far less imperative. In all these changes the accumulator wiU have its part to pTay. A revival of electrical energy stored, till wanted will be a necessary part of aB systems for electric distribution, whether, for the purpose ot lighting or for motive power." The invention of the accumulate* bad arisen out of the study of an obscure, an* unpromising detail, the so-called polarisation of light, and there might be other details which would equally repay investigation. Several questions were asked, and in reply to one of them Professor lhompson expressed the opinion that the cost of uhe electric lights in the room was loss than the cost of gas would ba for a mansion which had to provide its own apparatus for the making of gas.