Results of Crystal Analysis. 



513 



lain 



right number of atoms in the elementary cell and exp \ 

 the fact that the numbers in anatase are just half the nun , 

 found for rutile. We should probably state this fact in 



Fig. 3. 

 Anatase 













(100) 



1 









1 





toon 











1 



1110) 







1 





(112) 









— ■ - - 



.1, 



(III) 



best way by writing the molecular formula of anatase ' ?' 

 and that of rutile (Ti0 2 ) 2 , then we should have in ° 

 crystals J molecule associated with the elementary cell. 



The Position of the Oxygen Atoms. 



-on of 



§ 6. A fact of the first importance for the determinate 

 the positions of the oxygen atoms is, that the faces (100 \ . 

 (001) give spectra with very different relative intens , 

 This fact excludes any pseudocubic arrangement, or .^ 

 tetragonal structure is also in the present case to be asc] 

 to a tetragonal arrangement of the oxygen atoms. TO nal 



The oxygen atoms cannot be arranged with tetrap ,, 

 symmetry in a plane perpendicular to the c-axis, as h i , , 

 case of zircon and xenotime. Such an arrangement v 



