Licence: Public Domain Mark
Credit: Lessons in elementary physics / by Balfour Stewart. Source: Wellcome Collection.
476/502 page 456
Licence: Public Domain Mark
Credit: Lessons in elementary physics / by Balfour Stewart. Source: Wellcome Collection.
![reverse E.M.F. |iroduced by tlic gases liydrogen and oxygen at the pladnnm ]ila(es. Tins is the principle of Grove's gas battery, which is an early form of a second.ary ballcry. A great improvemenl was made by G.'islon l’l:mle, who sub- slilnted lead for platinum. The le.ad jilates were immersed in diluted sulphuric acid and connected with a battery (see Fig. 153) ; the result of the electrol3'sis is that hydrogen will escape at the cathode, whilst oxygen combines with the anode, forming lead peroxide (PbO.,). If now the battprj' connections be reversed the previously formed peroxide is reduced to Spongy lead by the hydrogen, and peroxide is formed at the other plate. By continuing the charging and reversing periodically the plates may be to some depth converted into spongy lead on one plate and into peroxide on the other plate. The cell is now said to be formed and has an E.M.F. of two volts. On discharging the cell the spongy lead and the perox- ide are converted into lead sul- phate. To charge the cell it is only necessary to connect it with some source of current when the sulphate of lead is converted at one plate into lead and at the other into peroxide. The forming maj' be acceler- ated by the process suggested by Faure of pasting red oxide of lead on the plates. Many improvements have been made in the details of the process, so as to increase the capacity, durability, and efficiency of the cells. The method of manu- facture most commonly employed is into the form of grids and to fill up Fig. 153a shows one of the large cells composed of 15 plates. It is capable of giving a current of 30 amperes for ten hours. Storage cells h.avc many import.ant applications. Thej’ have replaced to a large extent all forms of primary batteries \vhenever a strong current is required. Thej’ are especially usefid in connection with central electric light stations as a reserve of electric energy. A46. The Incandescent or Glow hamp.—The modern form of this lamp is associated with the names of Edison and Swan, Ph Ph PbC -F-“ Fi(i. 153- to cast the lead plates the spaces with oxide.](https://iiif.wellcomecollection.org/image/b21500368_0478.jp2/full/800%2C/0/default.jpg)
