ATOMIC WEIGHTS 513 



data, the latter tending to show that cerium oxide is a mixture of at least 

 two earths. One of these, of a dark salmon color, he ascribed to a new 

 element, " meta-cerium." The other he called cerium, and gave for it a 

 preliminary atomic weight determination. The pure oxalate, by Gibbs' 

 method, gave 46.934 per cent, of CeOo, and, on titration with potassium 

 permanganate, 29.503 and 29.506 per cent, of C^Os. Hence Ce = 139.62. 

 In mean, this ratio may be written — 



3C„03:2CeO„:: 100: 159.074 



which will be combined with other corresponding expressions later. 



Wyrouboff and Yerneuil ' determined the atomic weight of cerium by 

 analyses of the sulphate, 062(804)3.81120. The salt was prepared from 

 three different sources, two samples from monazite, and one from cerite. 

 It was dehydrated at 250°, and reduced to CeOo at 1500°. The latter 

 was perfectly white. The weights were as follows : 



Hydrous sulpliate. Anhydrous sulphate. CeO„. 



Hence the following percentages 



'Bull. Soc. Chim. (3), 17, 679. 1897. Also Ann Chim. Phys. (8), 9. .349. Moissan, Compt. 

 Rend., 124, 1233, also describes white eerie oxide. 



