294 EARTHS PROPER. 



Silica . . . 40-531 



Alumina . . . 32*726 



Lime . . . 24-24-5 



Potash with some soda 1-812 



Oxide of iron . . 0-182 







99.4,96 



Here the alkali differs both in quantity and kind 

 from that found by Gmelin, and the oxide of 

 iron is not quite jth of the quantity obtained by 

 that chemist. Let us calculate the composition 

 of this mineral, on the same supposition as we 

 made when calculating the result of Gmelin's. 



(1.) 2-25 : 2 : : 32-726 : 29-08 = silica united to the alu- 

 mina. 

 (2.) 3-5:2:: 24-245 : 13-854 = silica united to lime. 



But 29-08 + 13-854 = 42-934, which exceeds 

 the silica found in the mineral by 2-403 grains. 



The silica united to the lime is g^yth of the 

 whole. Now jfoth of 2-403 is 0*777, which be- 

 ing subtracted from 2*403 leaves 1-626 to be 

 taken from the 29*08, making 27*454 for the 

 amount of the silica actually united to the alu- 

 mina. Now, 



27*454 : 32-726 : : 2 : 2-3841 = atomic weight of alumina. 



Professor Strom eyer likewise analyzed a spe- 

 cimen of meionite from Sterzing in the Tyrol, 

 and found its constituents as follows :* 



* Untersuchungen, I. 590. 

 16 



