231 



2, =b .048 



Hence La = 140.484. 



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, puri- 

 fied by repeated crj^stallizations. In two experiments the 

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

 others the lanthanum was precipitated as oxalate, and con- 

 verted into oxide by ignition. The following percentages 

 are given for LajOg : 



^'■^ I By calcination. 



57-58 J 



^'■^ /- Ppt. as oxalate. 

 57-55^ 



Mean, 57.5475. ± -Oi'S 



The atomic weight determinations of Holzmannf were 

 made by analyses of the sulphate and iodate of lanthanum, 

 and the double nitrate of magnesium and lanthanum. In 

 the sulphate experiments the lanthanum was first thrown 

 down as oxalate, which, on ignition, yielded oxide. The 

 sulphuric acid was precipitated as BaS04 in the filtrate. 



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

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



