POLARIZED SPECTRA OF DOUBLE CHLORIDES. 



117 



molecular weight, NH 4 and K show again a longer interval than do Rb 

 and Cs. Averaging by series affords no such direct indication as to 

 differences of interval, as will appear from table 38. 



It will be noted that while the averages for the green and white com- 

 ponents of fluorescence are in very close agreement at +20 and also 

 at - 185, there is a difference of about 0.5 between the averages for 

 +20 and those for -185; also that the interval is greater for each 

 individual series at 185 than at +20, with the single exception of 

 ew. This difference does not appear, however, in the case of the absorp- 

 tion intervals. 



TABLE 37. Average frequency intervals, +20 C. and 185 C. 



Average frequency intervals, 185 C. 



