UAUUAM AND BKAZIL,. 123 



(Per lOQ parts) 



Water 0.666 



Oxide of titanium 2.666 



Glucina 16.000 



Silica 5.999 



Alumina 68.666 



Protoxide of iron 4.733 



98.730 

 100.000 



Loss 1 .270 



In estimating these constituents according to the electro- 

 clieniical theory, I believe that the oxide of titanium, not- 

 withstanding its important agency in the analytical experi- 

 ments, must be regarded as an accidental ingredient, as well 

 as the oxide of iron, which in some measure may have been 

 derived from the iron mortar. As the cymophane of Brazil 

 appears to be constituted more conformably to the hypothe- 

 sis of chemical proportions than that of Haddam, the follow, 

 ing calculation may be made, founded on its composition, 

 which gives for the essential constituents of Chrysoberyl, 



(Per inn part a) 



Silica 6.61 containing Oxygen 3.3S 



Alumina 75.75 35.38 



Glucina 17.64 5.49 



and very nearly corresponds with the following mineralogi- 

 cal formula, A*S-»-2GA*. 



