39* A Preliminary Note on the Use of Storage Cells 



in Bengal* 



By Satish Chandra Mukerjee, M.A., B.Sc. 



In connection with our work on "The Electrical State of 

 Nascent Gases ' ' [Journ. Asiat. Soc. Beng. Vol. iii, 1907], Profes 

 sor Cunningham and I have, for the last five years, been using a 

 battery of small storage cells, supplied by G. Pye & Co. 

 Though we strictly followed the directions given by the Com- 

 pany, we found that the cells were rapidly becoming useless 

 owing to the corrosion of the top parts of the plates (mostly, 

 the positive plates). The average life of an individual cell 

 varied from three months to one year. Many precautions 

 having proved unsuccessful I at last thought of using acid of 

 less concentration than what is recommended for use in Eng- 

 land, viz., acid of sp. gr. 1190. 



After several trials I found acid of sp. gr. 1150 to give the 

 best results. The cells filled with acid of this specific gravity 

 were charged in November, 1908. As the cells are still in good 

 order, it is too early to state the period of their life under the 

 new conditions ; but evidently it is much longer than when 

 acid of sp. gr. 1190 or 1180 was employed. 



The reason of the above experimental result is most pro- 

 bably this. The velocity of chemical reaction of dilute sul- 

 phuric acid on metallic lead and lead peroxide, to which the cur- 

 rent of the secondary cells is due, increases with temperature 

 and is, therefore, greater at temperatures of 30° to 35°C. which 

 obtain in Bengal l than at temperatures 15° to 20°C. which 

 obtain in England. This greater velocity is injurious to the 

 life of the cells, giving rise to too much lead sulphate at the ex- 

 pense of lead and lead peroxide of the plates. As a matter of 

 fact, the breaking of the plates was preceded by the appearance 

 of a white deposit of lead sulphate at the point of hreakage. 

 Thus to bring down the velocity of reaction it is necessary to 

 decrease the concentration of the acid employed. 8 



Professor E. P. Harrison has recently shown that to use 

 acid of the arae concentration as in England, viz., 20% acid, we 

 must take acid of sp. gr. 1183 instead of that of sp. gr. 1190. 

 The better results I have obtained with acid of even less con- 

 centration is probably due, therefore, partly to a tempera- 

 ture density effect, and partly to the increase in the velocity of 

 chemical reaction with rise in teni|>erature as has been pointed 

 out above. 



Further investigations on this subject are in progress. 



l It was observed that the breakage of the cells wm quicker in 

 summer than in winter. 



Refer to the current number. 



