THE SULPHATES. 



177 



the shorter frequency interval of 70=^. A few end members of the 

 reversing system, which presumably extends throughout the fluores- 

 cence region, were discernible. Determinations were made in part by 

 photographing the spectrum of the light transmitted by thin layers, 

 in part by the method of reflection. 



In table 106 the frequencies of the bands in the spectra of the 6 

 sulphates are arranged by series. Each series, as usual, is designated 

 by a small letter corresponding to the capital letter which denotes the 

 fluorescence series to which it is related. 



TABLE 106. Absorption spectra of uranyl sulphates at 180 C. 



