ATOMIC WEIGHTS 



497 



ignition, gave .2705 grni. of La.,Oo, or 57.068 per cent. Hence La = 

 135.64. .7045 grm. of the sulphate also gave .8815 grm. of BaSO^. 

 Hence 100 parts of BaSO^ are equivalent to 79.921 of La,(S04)3, a»<l 

 La = 135.74. 



From Cleve we have two separate investigations relative to the atomic 

 weight of lanthanum. In his first series ' strongly calcined LaoO..,, spec- 

 troscopically pure, was dissolved in nitric acid, and then, by evaporation 

 with sulphuric acid, converted into sulphate : 



1.9215 grm. La,0:< 



2.0570 



1.6980 



2.0840 



1.9565 



jave 3.3365 grm. sulphate. 

 3.5705 

 2.9445 

 3.6170 

 3.3960 



57.590 per cent. 



57.611 



57.667 



57.617 



57.612 



Mean, 57.619, ± .0085 



Hence La = 139.28. 



In his second paper,' published nine years later, Cleve gives results 

 similarly obtained, but with lanthanum oxide much more completely 

 freed from other earths. The data are as follows, lettered to correspond 

 to different fractions of the material studied : 



cent. 



Mean, 57.480, ± .0040 

 Hence La = 138.35. 



Brauner, in 1882, published Iavo sets of determinations, both based upon 

 the conversion of pure LaoOg into La2(S04)3. 



In his first paper, Brauner ^ gives only two sj'ntheses, as follows : 



1.75933 gi-m. La-.Os gave 3.05707 La-^CSOi),,. 

 .92417 " 1.60589 



57.566 per cent. 

 57.549 



Mean, 57.5575, ± .0057 



Hence La = 138.87. 



iJi. Svensk. Vet. .Akad. Hanrning.ir, Bd. 2, No. 7. 1874. 

 2K. Svensk. Vet. .\kad. Haridlingar, No. 2, 1SS3. 

 ' Monats. Cheni., 3, 1. 



