108 Chemistry of the Plante Cell. [June 11, 



The cause of the pink colour of the acid noticed by Mr. Crompton 

 and others was investigated, and found to be permanganic acid, 

 formed probably from the manganese present in commercial lead. 



In conclusion, the author points out : 



That "peroxides" are found in appreciable quantities in the 

 electrolyte during charge and discharge ; 



That their influence must not be neglected in considering the 

 behaviour of the Plante cell ; 



And that it is to the electrolyte rather than to the plates that 

 attention must be directed if any considerable improvement is to be 

 effected. 



IV. " A Study of the Plante Lead-Sulphuric Acid-Lead Peroxide 

 Cell, from a Chemical Stand-point. Part II. A Discussion 

 of the Chemical Changes occurring in the Cell." By H. E. 

 ARMSTRONG, F.R.S., and G. H. ROBERTSON. Received 



June 4, 1891. 



(Abstract.) 



The authors arrive in this paper at the following conclusions : 



1. That the cooling observed in the Plante cell can only be ex- 

 plained as resulting from the dissociation of the dilute sulphuric acid ; 

 and as the values given by Messrs. Ayrton, Lamb, Smith, and Woods 

 are in practical agreement with those calculated on the assumption 

 that the acid used is sulphuric acid itself, H 2 S0 4 , that in all proba- 

 bility such acid and not the dilute acid contained in the cell is opera- 

 tive throughout. 



2. That the observed loss in efficiency cannot be due to temperature 

 changes, as these arise through actions occurring out of circuit. 



3. That it is difficult from a comparison of calculated with observed 

 values of the E.M.F. to arrive at any final conclusion as to the exact 

 nature of the changes which take place in the cell. On the assump- 

 tion that sulphating occurs at both plates in circuit and under the 

 influence of H 2 S0 4 , the calculated value is considerably too high ; 

 while, if sulphating occur only at the lead plate, the value calculated 

 is far too low. 



4. That a counter E.M.F. of about 0*5 volt would account for the 

 observed departure from the highest calculated value. As peroxides 

 are always present in the electrolyte, it is conceivable that such a 

 counter E.M.F. may exist ; moreover, there is also the possible in- 

 fluence of the lead support to be considered. 



5. That the observed loss of efficiency is to be attributed to the 

 formation of peroxides in the electrolyte, and to the excessive sulphat- 

 ing occurring chiefly at the peroxide plate in the local circuit existing 

 between the support and the paste. 



