L12 



A STUDY OF THE ABSORPTION SPECTRA. 



at this concentration being about 100 Angstrom units. For the 0.06 

 normal solution the blue-violet and ultra-violet bands have completely 

 merged and the limit of absorption is about X 4600. 



The Uranyl Bands of the Acetate. 



The following table gives the approximate wave-lengths of the uranyl 



bands of the acetate in water and in methyl alcohol, and of the anhydrous 



powder: 



Bands of uranyl acetate. 



From this table it seems that the positions of the bands of the acetate 

 under these different conditions are about the same. 



Uranyl Acetate, Temperature Effect. 



A spectrogram showing the effect of rise in temperature was made for 

 a 0.0039 normal aqueous solution of uranyl acetate 196 mm. deep. The 

 exposures were made for 30 seconds to the Nernst glower, with a current 

 of 0.8 ampere and a slit-width of 0.20 mm. No exposure was made to the 

 spark at all. The temperatures, starting with the strip nearest the com- 

 parison spectrum, were 6, 18, 30, 43, 56, 68, and 75. 



The spectrogram shows the ultra-violet and blue-violet bands common 

 to all uranyl salts. The transmission band between these absorption bands 

 is about 200 Angstrom units wide and changes very little with change in 

 temperature. The blue-violet band advances rapidly towards the red as 

 the temperature rises. At 6 the blue-violet band extends from X 3950 

 to X 4500. The latter edge gradually runs towards the red until at 75 it 

 is about X 4600. The uranyl bands a and b appear. They are very weak 

 and gradually shift towards the red with rise in temperature. 



Spectrophotography of Chemical Reactions of Uranyl Salts. 



Plate 81, B, represents the absorption spectrum of a solution 15 mm. in 

 depth and containing an 0.08 normal solution of a uranyl salt in water. 

 Beginning with an 0.08 normal solution of uranyl nitrate, sulphuric acid 

 was added so as to make the concentration of acid beginning with strip 1 

 as follows: 0.37, 0.73, 1.46, 2.92, 5.84, 10.22, and 14.60 normal. 



It will be seen that in strip 1 we have practically the sulphate spectrum, 

 most of the nitrate having been transformed. The addition of more acid 

 does not produce any marked change until we reach the sixth and seventh 

 strips. Here we see that the c and d bands are very greatly shifted, so that 

 in the latter strip they form a single band. Several of the other bands are 

 considerably shifted towards the red. Throughout the changes of conditions 

 above named, the bands remain quite sharp and well defined (for uranyl 

 bands), and change very little in intensity. This is in quite marked 



