POLARIZED SPECTRA OF DOUBLE CHLORIDES. 



119 



shift. Thus, for example, the position of C w would be modified by the 

 presence of the overlapping of D g or C g ; D g by C g , etc. In short, it is 

 probable that if observations could be had on crystals which at 185 

 preserved their structure, the difference in interval between +20 and 

 185 would disappear. 



THE INFLUENCE OF MOLECULAR WEIGHT UPON THE POSITION OF BANDS. 



While some doubt may be felt as to the validity of the suggestion, 

 based upon the averages presented in the foregoing paragraphs, that 

 there is a relation between frequency intervals and the molecular 

 weight, there can be no question as regards the influence of molecular 

 weight upon the position of the bands. 



.60 



.55 u. 



.50 jt 



J L 



Rb 

 Cs 



K_ 

 NH_, 

 Rb_ 

 Cs 



K_ 



NH_, 

 Rt) 



J L 



J L 



Rb_ 

 Cs 



K 



Rb_ 

 Cs 



J L 



Rb_ 

 Cs 



K 



NH, 

 Rb_ 

 Cs 



K_ 

 NhU 



Rb_ 

 Cs 



20 



21 



22 



23 



24 



25 



FIG. 76. 



If we select a typical region in the spectrum and arrange the bands 

 belonging to a single group as in table 39, we find a general drift of the 

 various bands toward the violet as we pass from salt to salt in the 

 order K, NH 4 , Rb, Cs. 



