346 THE ATOMIC WEIGHTS. 



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 La 2 3 were found : 



23-454 

 23.419 

 23.468 



Mean, 23.447, .0216 



The formula of this salt is La 2 (I0 3 ) 6 .3H 2 0. 



The double nitrate, La 2 (N0 3 ) 6 .3Mg(N0 3 ) 2 .24H 2 0, gave the following 

 analytical data : 



Salt. H^O. MgO. 



53 2 7 g rm - I 569grm. .0417 grm. .1131 grm. 



5931 " -1734 " -0467 " .1262 " 



.S 662 " .1647 " -0442 " .1197 " 



3757 " .0297 " .0813 " 



.3263 <( .0256 l< .0693 " 



These weighings give the subjoined percentages of La 2 3 : 



21.231 



21.278 

 21.141 



21.640 

 21.238 



Mean, 21.3056, .058 



These data of Holzmann give values for the molecular weight of La 2 s 

 as follows : 



From sulphate , La 2 O 3 = 322.460 



From iodate " 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 2 O 3 and .586 grm. BaSO 4 . 



The La 2 3 was found by precipitation as oxalate and ignition. The 

 BaSO 4 was thrown down from the filtrate. Reduced to the standards 

 already adopted, these data give for the percentage of La 2 O 3 in the anhy- 

 drous sulphate the figure 58.668. 79.117 parts of the salt are propor- 

 tional to 100 parts of BaSO 4 . 



* Journ. fur Prakt. Chem., So, 33. 1860. 



