YTTRIA, 333 



Now, 17-857 + 1-928 + 5-672 = 25-457, which 

 exceeds the fluoric acid found in the mineral by 

 0-007 grain. But rj& part of the fluoric acid are 

 united to the lime and the cerium, so that only 

 rlhy of 0-007 or 0-00056 grain require to be sub- 

 tracted from 1-928, to have the fluoric acid ac- 

 tually united to the yttria, according to the 

 analysis. This amounts to 1*9224. And 



1-9224 : 8-1 : : 1-25 : 5-2668 = an atom of yttria. 



6. There is still another mineral, namely, the 

 yttrotantalite, which appears to consist essen- 

 tially of oxide of tantalum and yttria united to- 

 gether. But the other constituents vary so much, 

 that no greatreliance can be put on the analyses 

 hitherto given, the specimens appearing all ex- 

 ceedingly impure. There are three varieties, 

 which differ a good deal from each other in the 

 proportions of their constituents. The first 

 variety has a black colour, and was found by 

 Bcrzelius composed of 



