DISCHARGED STORAGE BATTERY PLATES, 283 



10 g, of Sodium Bicarbonate, filtered and washed. I acidulated 

 half the filtrate with Nitric Acid, boiled with a solution of 

 Barium Nitrate, allowed the white precipitate of BaSO^ to 

 subside ; then filtered, washed, dried the precipitate, ig-nited 

 it, cooled, and weighed •2-211 g., less ash "033 = 2*208 g.; 

 double this = 4-416 g., deduct -038 g. as the equivalent of 

 the Sulphate in the NaHCO., used, and there is left 

 4-378 g. BaSO^ = 72-82 per cent. Barium Sulphate = 

 30 per cent. SO^, corresponding to 94*68 per cent, of ]jead 

 Sulphate. 



2. I took l-644g., dissolved it in 5c. c. of hot Hydrochloric 

 Acid, diluted with water, allowed it to stand for the Lead 

 Sulphate to subside, filtered, washed with weak spirit, dried, 

 ignited, cooled, and weighed 1-584 g., less ash -003 g. = 

 1-581 g. ; deduct -04 g. for the Sulphuric Acid in the so-called 

 pure Hydrochloric Acid, and there is left 1*541 g., or 93*73 

 per cent, of Lead Sulphate. 



3. I fused a weighed quantity with Sodium Bicarbonate in 

 a crucible ; then broke up the crucible, and boiled for a long 

 time in water. It evidently did not all dissolve, as I only 

 found about "21 per cent. SO^ a,fter precipitating with a 

 Barium salt. The method of merely boiling with water and 

 the alkaline carbonate is evidently much pi'eferable to that 

 of fusion. 



4. I took 2*353 g. and macerated it in successive portions 

 of a cold saturated solution of Sodium Chloride for a week. 

 The residue, after Avashing and drying, Aveighed *333 g. ; 

 hence 85-85 per cent, of Lead Sulphate had gone into 

 solution. This is a much better result than the similar 

 experiment with the positive filnng, and seems to point to the 

 physical state of aggregation of the particles as the deter- 

 mining cause of the difference in solubility. Probably a 

 freshly precipitated Lead Sulphate would be entirely soluble, 

 but the method is too unreliable for use with old samples such 

 as these. 



I also used these Sodium Chloride solutions for deter- 

 mining the Sulphates with Barium Chloride in both plates ; but 

 the results were wrong, and I found the error to be due to the 

 presence of Sulphate in the so-called pure Sodium Chloride. 

 The mean of the first two determinations was — ,><t^T" 

 No. 1,94-68 

 No. 2, 93-73 ^>y^^ 



Mean, 94-2 per cent. PbS04, corresponding ti?0 



64*35 per cent. Lead. oJit- ' 



