ALUMINA. 303 



amounts to ^WrrTrth part of the whole. And the 

 y-*T77rrth part of 0-941 = 0-273, which being 

 taken from 0-941 leaves 0-668, which must be 

 added to the 46-666 given by theory. Now 



47-334 : 17'5 : : 6 : 2-2183 = atomic weight of alumina. Gives 



2-2183. 



12. ALBITE. 



Albite is a name given to a mineral which was Albite 

 long confounded with felspar. Eggertz * first 

 pointed it out as a distinct mineral j it was after- 

 wards analyzed by Stromeyer from Chesterfield 

 in North America, by whom it received the 

 name of IdesdspatliA Mr. Brookes has called it 

 cleavelanditeA Rose has given a minute descrip- 

 tion of the crystals of this mineral, which differ 

 a good deal from those of felspar. 



Stromeyer found an uncrystallized specimen 

 from North America composed of 



Silica . . . 70-676 



Alumina . . . 19-801 

 Soda . . . 9056 



Lime . . . 0-235 



Oxide of iron and manganese 0-111 



99-879 



Rose found the specific gravity of albite to 

 vary from 2-608 to 2-619. The constituents of 

 the crystals he found 



* Af hondlingar, V. p. 27. f Untersuchungen, p. 300. 

 \ Introduction to Crystallography, p. 459. 



