LANTHANUM. 



345 



give maxima and minima for BaCl.. In another column I give La,(S0j3 

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



latter : 



BaCl-i. 



12.765 — 12.825 grm. 



13-195 — 13-265 " 



1 1.669 — 1 1.749 " 



13.920 — 14.000 " 



"•734— 11.814 " 



13.813 — 13.893 " 



lo.oSo — 10.160 " 



11.204 — 1 1.264 " 



II. 1 1 1 — 1 1. 171 " 



La.,{SO,),. 



1 1.644 g'"i- 

 12.035 " 

 10.690 " 

 12.750 ' " 



10.757 " 



12.672 " 



9.246 " 



10.292 " 



10.192 " 



Ratio. 

 91.004 

 90.968 

 91.297 



9'-332 

 91.362 



91-475 

 91-364 

 91.615 

 91.482 



Mean, 91.322, zb .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.^Oa : 



^' ■-' >■ By calcination. 

 57.58 J 



57-5°1 - 



y Ppt. as oxalate. 



57-55 J 



Mean, 57.5475, -^ -0115 



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

 ses of the suli)hate 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^ in the filtrate. 



La,{SO,\,. 

 .9663 grm. 

 .6226 " 



La.,0.,. 



-5'57 grm- 

 •3323 " 

 .4626 " 



BaSO^. 



1. 1 093 grm. 



.7123 " 



.9S69 " 



These results are best used by taking the ratio between the BaSO^, put 

 at 100, and the La.^O.,. The figures are then as follows : 



46.489 

 46 652 

 46.873 



Mean, 46.671, zb .075 



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



t Journ. fur Prakt. Chem., 75, 321. 1S58. 



