34 



FLUORESCENCE OF THE URANYL SALTS. 



and 13, but also in the determinations for other salts (tables 4 to 10) 

 wherever the final fluorescence band (8) has been observed. The 

 corresponding change in the absorption interval to conform with the 

 fluorescence interval is much more difficult to establish, because the 

 last absorption band toward the red is entirely invisible under ordinary 

 conditions. 



TABLE 13. Absorption and fluorescence bands of uranyl nitrate at +20 C. 



1 Absorption bands, excepting that at 0.5086 are from measurements 

 by Jones and Strong (Am. Chem. Journal, 1910). 



EFFECT OF WATER OF CRYSTALLIZATION BEHAVIOR OF SOLUTIONS. 



The effects of water of crystallization and the comparison of the 

 spectra of the solid uranyl compounds with those of their solutions are 

 to be treated at some length in subsequent chapters. A few points 

 which have been brought out in the course of our work on the spectra 

 at +20 C. are, however, recorded here. 



The effect of water of crystallization in the case of uranyl nitrate is 

 to shift the luminescence bands slightly in the direction of the longer 

 waves. (Compare the hexahydrate with the anhydrous form in table 

 1.) This is the effect which it would seem most natural to expect, since 

 the mass of the vibrating system is increased by the addition of water of 

 crystallization without any increase, so far as we know, in the elastic 



