FROZEN SOLUTIONS. 



199 



until a temperature of 60 was reached, behaved similarly. (See 

 fig. 99.) The more dilute aqueous solutions, e. g., the 1/200 and 

 1/500 normal, gave broad bands with no important shifts. 



The very dim, broad bands of the 1/1000 and 1/1 0,000 normal are 

 probably due to the production of different hydrates. 



TJRANYL NITRATE IN NITRIC ACID. 



The spectra of the normal aqueous solution diluted with nitric acid 

 in varying proportion are shown in figure 100. Data for 5 c.c. of acid 

 are given in tables 120 and 121. 



TABLE 120. 



The uppermost spectrum, denoted at the left by 20 : 1, was pro- 

 duced by slowly cooling to 180 and exciting to luminescence a solu- 

 tion of 20 c.c. of the normal aqueous solution mixed with 1 c.c. of acid. 

 The first effect of the acid was to bring out more distinctly the dimmest 

 bands of the aqueous solution. There was no marked shift or change 

 in resolution as the acid component was increased until the solution 

 contained 1 c.c. of normal aqueous solution to 2 c.c. of acid. With 

 further dilution, e. g., I c.c. of solution to 2.75 c.c. of acid, a marked 

 change in the spectrum occurred, for only a broad-banded series of 



