282 PROCEEDINGS OF SECTION B. 



salt solution, which would only indicate 2o'6 per cent. Lead 

 Sulphate, so that this method was a failure. 



Determination of Lead. 



1. I took 1-17] g\, dissolved it in dilute Nitric Acid with 

 the aid of some methylated spirit (therefore either reduced by 

 aldehyde formed and dissolved as nitrate, or dissolved with 

 the Acetic Acid formed by oxidation of the spirit). After 

 addition of Sulphuric Acid I let it stand a couple of days; 

 then filtered, washed the Lead Sulphate with weak spirit, 

 dried, ignited, cooled, weighed 1-273 = -87 Pb. = 74-29 per 

 cent. Lead. 



2. I look 1'345 g., and treated with Sodium Chloride 

 solution, as mentioned (detn. 4 of sulphate) ; the residue was 

 dissolved in Hydrochloric Acid and added to the solution ; 

 the whole was then nearly neutralised by Caustic Soda, 

 warmed, and a current of Sulphuretted Hydrogen passed 

 through until the Lead Sulphide was precipitated. The 

 precipitate was washed, dried, weighed by counterpoising with 

 another filter = 1-18 g.. Lead Sulphide = 1-022, or 75-91 

 per cent. Lead. 



3. I took 7*37 g., and fused it with Potassium Cyanide. 

 There was a brick-red slag, and a clean button of Lead, 

 which weighed 4-97 g., or 67-4 per cent. Lead, which is 

 obviously too low. 



The mean of determinations 1 and 2 may be taken as 

 correct, more especially as they agree with the results of the 

 Peroxide and Sulphate determinations. 



No. 1, 74-29 Peroxide, 36-55 = .31-66 per cent. Pb. 



No. 2, 75-91 . Sulphate, 20-34 = 43-85 per cent. Pb. 



Mean, 75-1 p.c. total Lead Total 75-51 per cent. Pb. 



Result. 

 The filling of the discharged positive plate consisted of — 



Peroxide of Lead 36-55 per cent. 



Sulphate of Lead 64-19 per cent. 



100-74 



Analyses of the Negative Plate-filling, 



Determination of Sulphate. 



1. I took 6-012 g. of the finely-powdered, bluish-slate- 

 coloured filling, and boiled it with an aqueous solution of 



•«». 



