74 THE ATOMIC WEIGHTS. 



of from the metal. One hundred parts of PbO, upon con- 

 version into PbS04, gained weight as follows : 



35-84 

 35-71 



35-84 

 35-75 

 35-79 

 35-78 

 35-92 



Mean, 35.804, ~ .018 



These figures are not wholly reliable. Numbers one, two, 

 and three represent lead oxide contaminated with traces of 

 nitrate. The oxide of four, five, and six contained traces 

 of minium. Number seven was free from these sources of 

 error, and, therefore, deserves more consideration. The 

 series as a whole undoubtedly gives too low a figure ; and 

 this error would tend to slightly raise the atomic weight of 

 lead. 



Still a third series by Turner establishes the ratio between 

 the nitrate and the sulphate ; a known weight of the former 

 being in each experiment converted into the latter. One 

 hundred parts of sulphate represent of nitrate : 



109.312 

 109.310 

 109.300 



Mean, 109.307, a= .002 



In all these experiments by Turner the necessary correc- 

 tions were made for weighing in air. 



For the ratio between lead chloride and silver we have a 

 series of results by Marignac and one experiment by Dumas. 

 There are also unavailable data by Turner and by Ber- 

 zelius. 



Marignac,* applying the method used in his researches 

 upon barium and strontium, and working with lead chlo- 

 ride which had been dried at 200°, obtained these results. 



* Tourn. fur Prakt. Chem., 74, 21S. 1S5S. 



