ELECTRICAL ENERGY, STORAGE OF. 



265 



requirements. When we send a current through 

 a battery in this manner, its energy is employed 

 to tear away the zinc from the oxygen with 

 which it is combined. This liberated zinc con- 

 stantly tends to recombine with the oxygen, 

 and in so doing sets up a current opposed to 

 the charging one ; this latter current must, 

 therefore, have a sufficient electro-motive force 

 to prevent this recombination. The counter- 

 electro-motive force manifests itself even in 

 ordinary batteries while they are furnishing a 

 current, resulting in its gradual weakening. 

 In this case a portion of the zinc is separated 

 from the solution by the action of the liber- 

 ated hydrogen, and this zinc in reuniting with 

 the oxygen sets up an opposing current. 



This action was noticed very shortly after 

 the invention of the voltaic cell, and the im- 

 provements successively made in this cell have 

 been chiefly with a view of preventing, or at 

 least minimizing, this counter-action. The 

 phenomenon to which the name " polarization 

 of the electrodes " was given, was studied by 

 many eminent electricians, but it was not until 

 taken up by M. Gaston Plant6 that it received 

 a thorough and comprehensive treatment, or 

 that a practical form of cell for utilizing the 

 secondary current was produced. Ritter, of 

 Jena, observed the phenomenon of polarization 

 in 1803, while studying the chemical action 

 of currents upon liquids, and later constructed 

 a secondary pile consisting of a series of disks 

 of copper separated by disks of cloth moist- 

 ened with sal-ammoniac. 



The phenomenon of polarization was placed 

 upon its true basis by the researches of Volta, 

 Marianini, and Schonbein, some years after 

 the experiments of Ritter, and our knowledge 

 of it further enlarged by the labors of Davy, 

 De la Rive, and Faraday. In 1842 Grove con- 

 structed his now well-known gas -battery, 

 which consisted simply of two plates of plat- 

 inum dipped into acidulated water. A cur- 

 rent being passed through this battery, the 

 water is separated into its constituents, oxy- 

 gen and hydrogen. Platinum possesses the 

 property of condensing these gases upon its 

 surface. One of the platinum plates becomes 

 coated with oxygen, and the other with hydro- 

 gen, as the decomposition of liquid proceeds. 

 These gases constantly tend to reunite, and, 

 when the charging current ceases, the energy 

 stored in these separated gases is given out by 

 their recombination as heat if the gases are 

 mixed and burned, as electric energy if the 

 gases are allowed to recombine through the liq- 

 uid. The subject was taken up in 1860 by M. 

 Plante, who re-examined the whole question, 

 and experimented with many different rnetals 

 as electrodes and many different liquids as elec- 

 trolytes. His experiments resulted in showing 

 that the best results were given with lead elec- 

 trodes immersed in dilute sulphuric acid. Such 

 a cell can furnish no current before it has first 

 been charged by means of a current, as there 

 is no chemical difference between the plates. 



When, however, a current is sent through the 

 cell, the liquid is decomposed, and the oxygen 

 escaping at one electrode combines with the 

 lead, covering its face with a film of peroxide. 

 Plante found that to get this film sufficiently 

 thick and also to get the other plate in the 

 best form for effective action, the current had 

 to be sent through the cell a great number of 

 times, first in one direction and then in an- 

 other. When the current is reversed, the hy- 

 drogen liberated combines with the oxygen 

 already on one electrode to form water, leaving 

 this plate with a spongy metallic surface which 

 facilitates its conversion into peroxide of lead 

 when the current is again sent in the opposite 

 direction. After being charged and discharged 

 a number of times, the plates are in a shape 

 for effective use, one plate being coated with 

 peroxide of lead, and the other having a 

 spongy, metallic surface. Upon then closing 

 the circuit of the battery a current is produced 

 which continues as long as there is a chemical 

 difference between the two plates, the chemical 

 action which takes place being the partial re- 

 duction of the oxidized plate, and the oxida- 

 tion of the metallic one. Plant6 applied his 

 battery to various industrial uses, chiefly in 

 surgical cautery ; but the time required to pre- 

 pare the cells for use, as also that necessary to 

 store up a charge, was too great, and the 

 capacity was also too small to allow them to 

 have any extended application in the rapidly 

 developing electrical appliances of the present 

 time. In 1880 M. Carnille A. Faure made a 

 change in the Plant6 cell, which, though very 

 simple in itself, was of great industrial impor- 

 tance, as by it the storing capacity of the cell 

 was largely increased, and the time necessary 

 to charge it much reduced. M. Faure's im- 

 provement consisted simply in coating both 

 electrodes mechanically with red-lead. With 

 this construction the oxide on one plate is re- 

 duced, and the other plate further oxidized to 

 the peroxide, when a charging current is sent 

 through the cell. This battery, having an im- 

 mediate commercial value, has been put very 

 prominently before the public, and its merits 

 examined into by a number of competent ex- 

 perts. Since Faure showed that the secondary 

 battery could become commercially service- 

 able, the attention of inventors has been 

 largely turned in this direction, and various 

 different accumulators have been brought out, 

 the object of the improvements being to reduce 

 the weight of material as much as possible in re- 

 lation to its storing power. To this end M. de 

 Meritens has devised a cell in which the lead 

 plates are constructed of thin, overlapping lam- 

 inse arranged in a manner similar to the slats 

 of Venetian blinds. It is more powerful than 

 a Faure cell of the same weight. In another 

 cell, devised by Messrs. Sellon and Volckmar, 

 the lead plates are perforated and the red-lead 

 forced into these perforations, thus giving a 

 much greater amount of the oxide per pound 

 of the metal than when oxide is on the surface 



