ATOMIC WEIGHTS 495 



These results are best used by taking the ratio between the BaSO^, put 

 at 100, and the LaoO.. The figures are then as follows: 



46.489 

 46.652 

 46.873 



Mean, 46.671, ± .075 



In the analyses of the iodate the lanthanum was thrown down as oxa- 

 late, as before. The iodic acid was also estimated volumetrically, but 

 the figures are hardly available for present discussion. The following 

 percentages of LajOg were found : 



23.454 

 23.419 

 23.468 



Mean, 23.447, ±: .0216 



The formula of this salt is La2(I03)6.3HoO. 



The double nitrate, La2(N03)«.3Mg(K03)2.24H20, gave the following 

 analytical data: 



These weighings give the subjoined perecentages of La^Og : 



21.231 

 21.278 

 21.141 

 21.640 

 21.238 



Mean, 21.3056, ± .058 



These data of Holzmann give values for the atomic weight of La 

 as follows : 



From sulphate La = 139.42 



From iodate " = 137.65 



From magnesian nitrate " = 138.65 



Czudnowicz ' based his determination of the atomic weight of lantha- 



Journ. prakt. Chem., SO, 33. 1S60. 



