ATOMIC WEIGHTS 519 



C. von Scheele/ also in 1898, gave three series of determinations. 

 First, by the synthesis of praseodymium sulphate, wliich, however, con- 

 tained a little lanthanum sulphate, as follows : 



Mean, 57.805, ± .0139 



Hence Pr = 140.53. 



The second series by von Scheele is somewhat obscure, being a combi- 

 nation of the oxalate and sulphate methods. A part of the oxalate was 

 converted into sulphate, and in another part the CoO, radicle was de- 

 termined by titration with permanganate solution. The proportion of 

 oxide in sulphate was also found. I give below the several percentages, 

 and also the ratio 3CoO, : Pr„(S0j3 : 



Sulphate from, oxalate. Per cent. C.O.. Pr.^O^ in sulphate. Ratio. 



These two series have small claims to consideration, and may be 

 regarded as preliminary. The third series, by the sulphate method, is 

 far better : 



1 Zeitsch. anorg. Cheni., 17, 310. 189S. 



