ZIRCONIA. 339 



are combined with silica in the state of trisilicates, 

 except the soda, which must be in the state of 

 bisilicate ; and let us consider the atomic weight 

 of zifrconia as 6, that of lime as 3-5, that of soda 

 as 4, and that of protoxide of iron and man- 

 ganese as 4) '5. 



(1.) 6 (atom of zirconia) : 6 (3 atoms silica) :: 11-102 : 



11-102 = silica united to the zirconia. 

 (2.) 3-5 (atom of lime) : 6 (3 atoms silica) : : 9785 : 16-77 



= silica united to the lime. 

 (3.) 4 (atom of soda) : 4 (2 atoms silica) : : 13-13 : 13-13 = 



silica united to the soda. 

 (4.) 4-5 (atom of protoxide) : 6 (3 atoms silica) :: 8-816 : 



1 1 -75 = silica united to the protoxide of iron and man- 



ganese. 



Now, 11-102 + 16-77 + 13-13 + 11-75 = 5 

 This is less than the whole silica in the mineral 

 by 0-573. As the silica in combination with the 

 zirconia constitutes A of the whole, it is obvious, 

 that, in order to have the quantity of silica united 

 to the zirconia in the eudialite, we must add ^ 

 of 0-573 = 0-12 to 11-102, which will raise it to 

 11-222. This gives us 



H'222 : 11-102 : : 6 : 5-Q358 = atomic weight of zirconia, 



according to the constitution of this mineral. 

 Though this number be under 6, yet it approaches 

 fully as near it as could be expected from so 

 complicated a mineral ; which, probably, was not 

 free from some admixture both of sodalite and 

 hornblende. 



Y2 



