ATOMIC WEIGHTS 



203 



Seties A. 



Mean, 159.9645, ± .0015 

 Mean from both series, 159.9704, ± .0010 



Hence Pb = 206.80. 



There is still another set of experiments npon lead nitrate, originally 

 intended to fix the atomic weight of nitrogen, which may properly be 

 included here. It was carried out by Anderson' in Svanberg's labora- 

 tory, and has also appeared under Svanberg's name. Lead nitrate was 

 carefully ignited, and the residual oxide weighed, with the follomng 

 results : 



5.19485 grm. PbN.O, gave 3.5017 grm. PbO. 67.4071 per cent. 

 9.7244 •' 6.5546 " 67.4037 



9.2181 " 6.2134 " 67.4044 



9.6530 " 6.5057 " 67.3957 



Mean, 67.4027, ± .0016 



Hence Pb = 207.34. 



The direct ratio between lead and silver has been roughly measured 

 by the electrochemical experiments of Betts and Kern.^ Lead silicofluoride 

 was dissolved in hydrofluosilicic acid, and from the solution the lead 

 was thrown down electrolytically, silver being simultaneously precipi- 

 tated by the same current. Two series of experiments gave the following 

 data. The ratio 2 Ag : Pb : : 100 : x is stated in the third column : 



1 Ann. Chim. Phys. (3), 9, 254. 1843. 



2 Trans. Amer. Electrochem. Soc, 6, 67. 



