834 



EARTHS PROPER. 



The second variety, which is yellow, was com- 

 posed of 



Oxide of tantalum 

 Tungstic acid 



Lime 



Oxide of iron 



Oxide of uranium 



60-124 

 1-044 



29-780 

 0-500 

 1-155 

 6-622 



99-225 



The third variety, which is dark brown, was 

 composed of 



Oxide of tantalum 

 Tungstic acid 

 Yttria 

 Lime . 

 Oxide of iron 

 Oxide of uranium 



51-815 

 2-592 



38-515 

 S-260 

 0-555 

 1-111 



97-848 



It must be obvious from a bare inspection of 

 these three analyses, that the ratios between the 

 oxide of tantalum and the yttria differ too much 

 in each, to enable us to deduce from them any 

 information, either respecting the atomic weights 

 of yttria or oxide of tantalum ; not to men- 

 tion the tungstic acid, the lime and the oxide of 

 uranium, which are still more variable. But a 

 comparison of the atomic weight of yttria, de- 

 duced from the analyses of gadolinite and yttro- 

 cerite, with the weights deduced from the car- 



