124 



FLUORESCENCE OF THE URANYL SALTS. 



the first band in the case of series D and E has been left out of con- 

 sideration on account of its relative uncertainty. For the other series 

 the interval, although less certain, has nearly the same value. It will 

 be noticed that there is nothing to indicate any change in the interval 

 as we pass from the longer to the shorter waves. 



TABLE 40. Series in the fluorescence spectrum of uranyl nitrate hexahydrate 



[UO*(N0 3 )i+6H 2 0}. 



1 Estimated. Str., strong; m., medium; d., dim; v. d., very dim. 



1 The most reliable results (as indicated by the number and consistency of the individual 

 measurements, the appearance of the negatives, etc.) are marked 5; the least reliable by 1. 

 3 The unit in which 1/X is expressed is such that for X=5,000 A. u. 1/X is written 2,000. 



In a spectrum consisting of so many bands, the occasional repetition 

 of any given interval between bands is to be expected, even if the bands 

 are distributed at random. It is proper to inquire, therefore, whether 

 this interval of about 86.0 really occurs more frequently than would be 

 expected for a random distribution. Data bearing on this point are 

 plotted in the upper curve of figure 77. In this curve horizontal dis- 

 tances indicate the lengths of different possible intervals between 



