494 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 54 



established. The method has already been described "under cerium. The 

 weighings give maxima and minima for BaCl,. In another column I 

 give Lao (804)3 proportional to 100 parts of BaCL, mean weights being 

 taken for the latter : 



Mean, 91.322, ± .048 



Hence La = 141.21. 



Although not next in chronological order, some still more recent ^vork 

 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 bv ignition. The data follow : 



0112 



Hence La= 138.81. 



The atomic weight determinations of Holzmann ° 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 lanthanum 

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

 sulphuric acid was precipitated as BaSO^ in the filtrate: 



