162 



FLUORESCENCE OF THE URANYL SALTS. 



TABLE 84. Summary of average intervals of the double acetates. 



ABSORPTION SPECTRA OF THE ACETATES. 



The fluorescence and absorption of the acetates are related to each 

 other in a manner entirely similar to that already established in the 

 case of the other uranyl compounds. 



The absorption bands occur in series of constant interval and this 

 interval is much shorter than that of the fluorescence series. Fluores- 

 cence and absorption overlap in the reversing region, with numerous 

 coincidences and an interlocking of the fluorescence and absorption 

 intervals. Reversals, both exact and of the well-known displaced type, 

 are more frequent, perhaps, than in any family of uranyl salts as yet 

 studied. A notable example occurs in the spectrum of lead uranyl 

 acetate (see fig. 86). 



RtVEBSAI 



FIG. 86. 



The absorption spectra fall into two fairly well defined classes : 



(1) Double acetates of Li, NH 4 , Na, K, Ca, Zn, Rb, Sr., Ag., Ba. 



In this class the system of bands having a series interval of 70 + 

 ends at about 2,180, where is located the head of the strongest series. 



Band E of the fluorescence series is usually missing in group 8 and is 

 supplanted by a strong absorption band (1) located 85 =*= frequency 



