LANTHANUM. 



345 



give maxima and minima for BaCl 2 . In another column I give La.,(S0 4 ) 3 

 proportional to 100 parts of BaCl 2 , mean weights being taken for the 

 latter : 



Ratio. 

 91.004 

 90.968 

 91-297 

 9'.332 

 9 r -3 62 



9L475 

 91.364 

 91.615 

 91.482 



Mean, 91.322, .048 



Hence La = 140.2. 



Although not next in chronological order, some still more recent work 

 of Marignac's * may properly be considered here. The salt studied was 

 the sulphate of lanthanum, purified by repeated crystallizations. In two 

 experiments the salt was calcined, and the residual oxide weighed ; in 

 two others the lanthanum was precipitated as oxalate, and converted into 

 oxide by ignition. The following percentages are given for La 2 O 3 : 



"'5 I By calcination. 



57.58 

 57.50 



57-55 



jPpt. 



as oxalate. 



Mean, 57-5475, - OII 5 



The atomic weight determinations of Holzmann f were made by analy- 

 ses of the sulphate and iodate of lanthanum, and the double nitrate of 

 magnesium and lanthanum. In the sulphate experiments the lantha- 

 num was first thrown down as oxalate, which, on ignition, yielded oxide. 

 The sulphuric acid was precipitated as BaSO 4 in the filtrate. 



5'57 

 .3323 

 .4626 



.9663 grm. 

 .6226 " 

 .8669 " 



1.1093 grm. 

 .7123 " 

 .9869 " 



These results are best used by taking the ratio between the BaS0 4 , put 

 at 100, and the La, 2 0. r The figures are then as follows : 



46.489 

 46652 

 46.873 



Mean, 46.671, .075 



* Ann. Chim. Phys. (4), 30, 68. 1873. 

 t Journ. fur Prakt. Chem., 75, 321. 1858. 



