284 PROCEEDINGS OF SECTION B, 



Determination of the Lead. 



1. I took 707 g. ; it dissolved easily in dilute Nitric Acid ; 

 after addition of Sulphuric Acid and Methylated Spirit it 

 was allowed to stand a couple of days, then filtered, washed 

 with weak spirit, dried, ignited, cooled, weighed '738 less ash 

 •003 -= -735 g. Lead Sulphate = -502 g. Pb = 71 per cent. 

 Lead. 



2. I took 1*442 g. and boiled it in an aqueous solution of 

 Potassium Hydrate until dissolved, then I added excess of 

 dilute Sulphuric Acid, let stand, filtered, washed and dried, 

 ignited and cooled, weighed 1-47 g. PbSO^ = 1-003 g. Pb, 

 corresponding to 69*55 per cent, of Lead. 



3. I fused 23*328 g. with Sodium Bicarbonate, Potassium 

 Cyanide, Sodium Chloride, and an iron nail ; there was a 

 clean button of Lead weighing 15*525 g., or G&o per cent. 

 Lead. This result, although better than in a similar experi- 

 ment with the positive filling, is still too low. Perhaps it 

 was due to the temperature of the furnace being too high, 

 or the crucible kept in it too long a time so that some Lead 

 was volatihzed. I suppose that the Iron would prevent any 

 Sulphide of Lead — that might have been formed — from 

 being held by Alkaline Sulphides in the slag. 



The mean of the first two determinations is — 



No. 1 71-00 



No. 2 69*55 



Mean 70*25 per cent, of Lead. 



As the total Lead is 70*25 per cent., and there was 94*2 

 per cent of Sulphate of Lead, which would contain 64*35 

 per cent, of Lead, it follows that there would be 5*9 per cent, 

 of Lead in the free state. 



Result. 



The filling of the discharged negative plate consists of — 



Sulphate of Lead 94-2 per cent. 



Metallic Lead 5*9 per cent. 



100*1 



