346 THK ATOMIC WEIGHTS. 



In tlie anal3'ses of the iodate tlie 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 

 23.46S 



Mean, 23.44.7, ± .0216 



The formula of this salt is La,(I03)6.3H,0. 



The double nitrate, La,(N03)e.3Mg(NO,)2.24H,0, gave the following 

 analytical data : 



These weighings give the subjoined percentages of La.,03: 



21.231 



21.278 

 21. 141 

 2 1 . 640 

 21.238 



Mean, 21.3056, dz .058 



These data of Holzmann give values for the molecular weight of La.^O^ 

 as follows : 



From sulphate La.,03 := 322.460 



From iodate " =r 320.726 



From magnesian nitrate " ^= 322.904 



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

 num upon one analysis of the air-dried sulphate. The salt contained 

 22.741 per cent, of water. 



.598 grm. gave .272 grm. La^Og and .586 grm. BaSO^. 



The La.^Og was found by precipitation as oxalate and ignition. The 

 BaSO^ was thrown down from the filtrate. Reduced to the standards 

 already adopted, these data give for the percentage of La203 in the anhy- 

 drous sulphate the figure 58.668. 79,117 parts of the salt are propor- 

 tional to 100 parts of BaSO^. 



* Journ. fiir Prakt. Chetn., So, 33. i85o. 



