DISCHARGED STORAGE BATTERY PLATES. 281 



water, dried, and weighed. It had not lost weight; the 

 filtrate did not contain any Lead ; yet this is a method 

 given for testing Red Lead for Lead. 



The mean determinations 1, 2, and 3 may be taken as 

 correct — 



r>a on f =36"55 WT CGiit. Peroxidfi, corresponding 

 sr-fi'l I to 31*66 per cent. Lead. 



Determination of Sulphate. 



1. I took 5*785g., boiled it in water with lOg. of Sodium 

 Bicarbonate, digested for some hours, and filtered it. I took 

 half the filtrate, acidulated it with ^Nitric Acid, boiled it with 

 Barium ]\itrate; allowed the Barium Sulphate precipitate to 

 subside, filtered, washed, dried, ignited, cooled, and weighed 

 1-451 g., less ash '003 = 1-448 g. ; double this = 2-896 g. 

 Barium Sulphate, corresponding to 1-193 g. SO^ ; deduct 

 "016 g. SO^jforthe Sulphate in the 10 g. Sodium Bicarbonate, 

 and it leaves 1-177 g. SO^ = 20-34 per cent. SO^, or corre- 

 sponds to 64-19 per cent. PbSO^, or to 43-85 per cent. Pb. 



2. The Acetates of Ammonium and Sodium are used for 

 dissolving out Lead Sulphate in mixtures. Their value is 

 lessened by their power of dissolving some Oxide of Lead ; 

 however, I found the method to be fairly accurate in this 

 case. 



I took 3*5805 g. and digested it with a solution of Sodium 

 Acetate, boiled, and filtered. To the filtrate I added a little 

 Sulphuric Acid, let it stand for some hours, filtered, washed 

 the precipate of Lead Sulphate, dried and weighed it, 2-347 g. 

 = 65-54 per cent. Lead Sulphate, 



The undissolved residue of Peroxide was washed, dried, 

 and weighed, 1*134 g., whereas it should have weighed 

 3*5805 - 2*347 = 1*2335 g. There was thus a loss of 

 *0995 g. of Peroxide, or probably a little more, which would 

 account for the percentage of Lead Sulphate being slightly 

 higher than in the first determination. 



3. 1 fused a weighed quantity with some Sodium Bicar- 

 bonate in a crucible, and poured the fluid mass into water, 

 boiled for a long time, and estimated as BaSO^, but only 

 got 13 per cent. SO^. I regard the failure as due to the very 

 slow solubility of the fused mass in water. 



4. I took 1*345 g. and macerated it in successive portions 

 of a cold saturated solution of Sodium Chloride during a 

 week. The residue was finally washed, dried, and weighed, 

 ^ 1 g. ; showing that only '345 g. had been dissolved by the 



