192 



FLUORESCENCE OF THE URANYL SALTS. 



The effect of dilution with acid at one temperature is given in table 

 115. The 180 vspectra of the 4/15 normal aqueous solution with 

 varying proportions of acid are shown in figure 95. With the addition 

 of acid the bands at first move toward the violet without resolving, then 

 become stationary in position, and finally resolve. The ratio by 

 volume of aqueous solution to sulphuric acid is given for each spectrum. 

 The shift is not the same for the different bands, because the frequency 

 interval, beginning with about 85 units for the aqueous solution, 

 increases with increase of acid component to about 90 units in the 50 

 parts acid to 1 part water solution. With the exception of the two 

 resolved spectra, the bands are too diffuse to permit of satisfactory 

 intermediate measurements on the frequency intervals. Dilution with 

 acid has undoubtedly increased the interval by 5 units, whereas dilu- 

 tion with water decreased the interval by 8 units. 



URANYL CHLORIDE IN WATER. 



The absorption spectrum of the chloride is of particular interest, 

 since Jones and Strong first located absorption bands 1 in the fluores- 

 cence region in an aqueous solution of this salt. Observations by the 

 authors on the transmission spectrum of several crystals of the uranyl 

 double chlorides of potassium, ammonium, rubidium, and caesium have 



TABLE 116. Uranyl chloride in water. 



resulted in the discovery of absorption bands in the same region. The 

 view held by Jones that the fluorescence spectrum is a continuation of 

 the absorption spectrum is to be gravely doubted, for while the chloride 

 solution shows a fluorescence band at 0.4926 and Jones has established 

 the position of an absorption band at 0.4920, none of the other bands 



1 Jones and Strong. Carnegie Inst. Wash. Pub. No. 130, p. 90. 



