452 DR T. THOMSON'S Analysis of some Minerals. 



Silica, 3.015 



Alumina, ..... 0.980 



Peroxide of iron, . . . 0.625 



Potash, 0.530 



4.95 



As hydrolite contains 29.866 per cent, of water, it is obvious, 

 that if the 5.3 grains analyzed had retained their water, the 

 weight would have been 7.53 grains. Consequently the consti- 

 tuents, according to the preceding analysis, considering the loss 

 as potash, and converting the peroxide of iron into protoxide, 

 are as follows : 



Silica, 3.015 or 39.896 



Alumina, .... 0.980 . . 12.968 



Protoxide of iron, . 0.5625 . . 7.443 



Potash, 0.7425 . . 9.827 



Water, . . . ... 2.2050 . . 29.866 



7.5050 100. 



This is equivalent to 



14 atoms silica, 



4 atoms alumina, 



1 atom protoxide of iron, 



1 atom potash, 

 18 atoms water. 



We may therefore consider hydrolite as a compound of 



4 atoms bisilicate of alumina, 

 1 atom bisilicate of potash, 

 1 atom quatersilicate of iron, 

 18 atoms water. 



