98 



SCIENCE 



[N. S. Vol. XLVII. No. 1204 



or by the dimness of the fluorescence. The 

 fluorescence bands were located by reference 

 to the strong lines of the mercury arc which 

 served as the source of excitation. 



TABLE I 



Bands Arranged in Series of Constant Intervals 



in the fact that nine of the nineteen series have 

 less than four members present. The remain- 

 ing ten series have flve or more bands present, 

 however, and it is worthy of note that the 

 system is sufficiently universal to include all 

 but three or four of the hands. The independ- 

 ence of the series is remarkably good — rarely 



TABLE n 



Bands Grouped around Mercury Lines {in Fre- 

 quency Numbers) 



An argument against arranging the bands 

 in series of constant intervals as outlined lies 



• Geissler tube lines. 



does a member of one series serve as a mem- 

 ber of another series. It is possible to ar- 

 range many of the bands in series of shorter 

 intervals, for at 1/A, = 2793 and 1/A. = 2793 



