1883.] 



Walker, John James, M.A. 

 Warren, Charles, C.M.G., Major 

 R.E. 



The following Paper was read : — 



67 



Watson, Professor Morrison, M.D. 

 Williams, Charles Theodore, M. A., 

 M.D., F.R.C.P. 



Chemistry of Storage Batteries. 



I. " Contributions to the Chemistry of Storage Batteries." By 

 E. Frankland, D.C.L., F.R.S. Received February 21, 

 1883. 



1. Chemical Reactions. — The chemical changes occurring during 

 the charging and discharging of storage batteries have been the 

 subject of considerable difference of opinion amongst chemists and 

 physicists. Some writers believe that much of the storage effect 

 depends upon the occlusion of oxygen and hydrogen gases by the 

 positive and negative plates or by the active material thereon, some 

 contend that lead sulphate plays an important part, whilst others 

 assert that no chemical change of this sulphate occurs either in the 

 charging or discharging of the plates. 



To test the first o£ these opinions, I made two plates of strips of 

 thin lead twisted into corkscrew form, and after filling the gutter of 

 the screw with minium, so as to form a cylinder that could be after- 

 wards introduced into a piece of combustion-tubing, these plates were 

 immersed in dilute sulphuric acid and charged by the dynamo- 

 current in the usual manner. The charging was continued until the 

 whole of the minium on the + and — plates respectively was con- 

 verted into lead peroxide and spongy lead, and until gas bubbles 

 streamed from the pores of the two cylinders. 



After removal from the acid the plates were superficially dried by 

 filter-paper, and immediately introduced into separate pieces of com- 

 bustion-tubing previously drawn out at one end, so as to form gas 

 delivery tubes. The wide ends of these tubes were then sealed before 

 the blowpipe, care being taken not to allow the heat to reach the 

 enclosed cylinders. The tube containing the cylinder of reduced lead 

 was now gradually heated until the lead melted, the drawn-out end 

 of the tube meanwhile dipping into a pneumatic trough. The gas 

 expelled from the tube consisted almost exclusively of the expanded 

 air of the tube and contained mere traces of hydrogen. 



The tube containing the cylinder of lead peroxide was similarly 

 treated, except that the heat was not carried high enough to decom- 

 pose the peroxide. Mere traces, if any, of occluded oxygen were 

 evolved. 



These results justify the conclusion that occluded gases play, practi- 

 cally, no part in the phenomena of the storage cell. 



With regard to the function of lead sulphate in storage batteries, 



f 2 



