^80 PROCEEDINGS OF SECTION B. 



11.— ANALYSES OF DISCHARGED STORAGE 

 BATTERY PLATES. 



By A. HE.VRICK JACKSON, B.Sc, F.C.S., &;c., Professor of Chemistry 

 at the Veterinary College, and Science Lecturer at the Grammar School, 

 Melbourne. 



The positive plate of a storage battery is said to be filled 

 with a paste of Sulphuric Acid, and either Red Lead or 

 Litharge. The iiega^tive plate is filled with a paste of Sul- 

 phuric Acid and either Litharge or a mixture of Litharge 

 and Lead Sulphate. 



During the process of charging the filling of the positive 

 plate is nearly all changed into Peroxide of Lead ; whilst 

 that of the negative plate is changed to metallic Lead. It is 

 regarded that the energy given out by the cell is due to the 

 change into Lead Sulphate of the Peroxide of the positive 

 plate, and of the metallic Lead on the negative plate during 

 discharge. 



Some plates having come into my hands for other purposes 

 than those of this paper, I thought it would be interesting to 

 determine the composition of the filling, and also to use 

 them as a means of comparing several different methods of 

 analysis. Some of the methods will be seen, from the results 

 appended, to be unreliable for the analyses of the mixtures 

 as they are present in these plates. 



Analyses of the Positive Plate Filling. 

 Determination of Peroxide. 



1. I took 17"939 grammes of the finely -powdered plum- 

 coloured filling, and treated it with Hydrochloric Acid. 

 Chlorine was given off', and received in an aqueous solution 

 of Potassium Iodide. The Iodine thus set free was titrated 

 by a standard solution of Sodium Thiosulphate, of which 

 508e.c. were required to decolourize it. This 508c. c. = 550c.c. 

 standard. Iodine solution = 1-95 grammes, Chlorine = 

 6'57 g.. Peroxide = 36'62 per cent. 



2. I took 8-202 g. : it required 246-77cc. of Thiosul- 

 phate = 25-2C.C., Iodine = 3-176 g., Iodine = '887 g., 

 Chlorine == 2*985 grammes, Peroxide = 36-39 per cent. 



3. I took 6-684 g. : it required 200c.c. of Thiosulphate = 

 205c.c., Iodine 2-45 g.. Peroxide = 36-65 per cent. 



4. I sifted 1-297 g. into 30c.c. of glacial Acetic Acid and 

 digested it on the outside of a water oven for three-quarters 

 of an hour, filtered, washed with the acid, and then with 



