1835.] 



Improvements in Science. 



267 



3. Spinelle. — M. Hermann khic\\( Bogg. 1831^ has found 

 this mineral composed of 



Silica 2-25 



Alumina .... 68*95 

 Magnesia . . . . 25*72 

 Peroxide of iron . . 3*48 



100*40 



4. Pleonaste. — Consists of, according to Abich, 



Silica . . . . 

 Alumina . . . 

 Magnesia . . . 

 Protoxide of iron 



2*50 

 65*27 

 17*58 

 13*97 



99*32 



5. Chabasite. — E. Hoffman has given the following ana- 

 lyses of this mineral, from different localities : (Pogg.Ann.) 



6. Radiolite. — Pfaff found this mineral to consist of 

 (Schweig Seidell xxiii. 394.) 



Silica 48 



Alumina 27 



Soda 10 



Magnesia ... * 3 



Water 10 



98 



