ATOMIC WEIGHTS 



.■)11 



weighed, not measured. In the third oolnran I give the ratio between 

 CeCls and 100 parts of silver: 



Mean, 76.155, ± .0065 



Eeduced to a vacuum this becomes 76.167. Hence Ce= 140.13. 



In a later paper/ Robinson discusses the color of eerie oxide, and 

 criticises the work of Wolf. He shows that the pure oxide is not white, 

 and makes it appear probable that Wolf's materials were contaminated 

 with compounds of lanthanum. He also urges that Wolf's cerium sul- 

 phate could not have been absolutely definite, because of defects in the 

 method by which it was dehydrated. 



Brauner,^ in 1885, investigated cerium sulphate with extreme care, 

 and appears to have obtained material free from all other earths and 

 absolutely homogeneous. The anhydrous salt was calcined with all 

 necessary precautions, and the data obtained, reduced to a vacuum, were 

 as follows : 



1 Chemical News, 54, 229. 1SS6. 



- Sitzungsb. Wien. Akad., Bd. 92. July, 18S5. 



