164 



of chalcolamprite could be procured sufficiently large to allow of 

 ascertaining that the mineral really contains silicic acid to the 

 very amount required for covering the loss. 



The analysis was performed by R. Mauzelius. For the 

 determination of silicic acid 0,6268 grams of material were used, 

 for determining the fluorine and Avater 0,4290 grams, and for the 

 determination of the other constituents 0,5138 grams. The 

 result obtained is as follows. 



Sb.,0.^ .... 59,65 



SiO^_ 10,86 



TiO^ 0,52 



>?rOo 5,71 



Ce^ O3 etc. . . 3,41 



Fe^O, .... 1,87 



MnO 0,44 



CaO 9,08 



K^O 0,38 



Na., 3,99 



ЛоО 1,79 



F., 5,06 



102,76 



— 2,13 



100,63 



Molecular ratios 

 0,223 



0,180 \ 



A ( 0,186 



0,006 j ' 



0,094 



0,030 



0,036 



0,006 J 0,396 



0,162 



0,004 



0,064 



0,100 



0,134 / 



0,234 



1,12 

 0,94 



1,18 



The molecular ratios of the niobic acid, the silicic and 

 titanic acids, all the bases, and the water consequently ap- 

 pi-oximate closely to 1:1:2:1, which gives the empirical 

 formula 



RNh,0^,F^-^RSiO.,. 



This result may be represented by the following structural 

 formula 



