YTTRIA, 331 



great care by Berzelius, who found its constitu- 

 ents as follows : 



Silica . . 25-80 



Yttria . . 45-00 

 Protoxide of cerium 16-69 



Protoxide of iron 10-26 



Volatile matter 0-6t) 



98-35 * 



Let us calculate the composition of this mineral, 

 on the supposition that the yttria and oxides 

 of cerium and iron are respectively in the state 

 of silicates, and that the atomic weights of all 

 of these constituents are as follows : 



Silica . . 2 



Yttria . . 5-25 



Protoxide of cerium 7*25 



Protoxide of iron 4-5 



(1.) 525 (atom of yttria) : 2 (atom of silica) : : 45 (yttria in 

 the mineral) : 17-14 = silica united to yttria. 



(2.) 7-25 (atom protoxide of cerium) : 2 : : 16-69 : 4-302 =s 

 silica united to the oxide of cerium. 



(3.) 4-5 (atom of oxide of iron) : 2 : : 10-26 : 4-56 = silica 

 united to the oxide of iron. 



Now, 17-14 + 4-302 + 4-56 = 26-002, which ex- 

 ceeds the silica found in the mineral by 0*2002 

 grain. 



The silica united to the oxides of cerium and 

 iron being one third of the whole, it is ob- 



' Afhandlingar, IV. 225. 



