FROZEN SOLUTIONS. 



193 



located by him at 0.6070, 0.6040, 0.6020, 0.6000. 0.5200, or 0.5185 

 coincide with a band of the fluorescence spectrum. Furthermore, it 

 has previously been indicated that often the last band of a fluorescence 

 spectrum coincides fairly well with a strong band in the absorption. 

 It has also been shown in our study of the fluorescence and absorption 

 spectra of the crystalline salts (see Chapters III to IX) that the interval 

 between the absorption bands, although constant, is much smaller 

 than that between fluorescence bands. 



The bands of the chloride in solution are separated by a very black 

 background, but are so dim that cooling to 90 is necessary before 

 measurements can be made. The bands continue to increase in 

 brightness as the temperature is further decreased. 



The temperature shift between 90 and 180 is toward the red 

 in the spectrum of the 3.0 normal solution. The measurements on the 

 chloride, to be found in tables 116 and 117, indicate that difficulty is 

 experienced in locating the positions of the bands. The remarkable 



TABLE 117. Uranyl chloride in water Frequencies and average intervals, fluorescence bands. 



