ATOMIC WEIGHTS 



529 



Mean, 47.812, ± .0010 



Hence Eu = 152.05. 



Urbain and Lacombe, for the same ratio, found 47. 798, ±.0027. The 

 two series combined give 47. 810, ±.00094. 



Feit and Przibylla' have also applied their volumetric method to the 

 determination of this atomic weight, with the following results: 



Mean, 152.565, ± .0170 



The four ratios for Eu now are^ 



(1). EU2 ( SO J 3.8H,0:Eiio(S04).:: 100: 80.426, ±.0038 

 (2). Eu,(SOJ,.8H„0:Eu203: :100:47.810, ± .00094 

 (3). Eu„(S04).,:EuA: : 100: 59.431, ± .0047 

 (4). 0:Eu: :16:152.565, ± .0170 



Eeducing these ratios with 8 = 32.0667, ±.00075 and H = 1.00779, ± 

 .00001 we have — 



From ratio 1 Eu = 151.991, ± .0542 



" 3 152.012, ± .0247 



" 2 152.035, ± .0048 



" 4 152.265, ± .0170 



General mean, Eu = 152.072, ± .0045 



In round numbers the atomic weight of europium is 152. 



1 Zeilsch. anorg. Chem., 50, 260. 1906. 



