60 THE ABSORPTION* SPECTRA OF SOLUTIONS. 



In addition to the ordinary uranous and uranyl bands, there is a weak 

 band about 15 Angstrom units wide at about X 5080. This band appears 

 best in the central strips, and can hardly be detected at all in the lowest and 

 highest strips. It is, therefore, difficult to say whether it is a uranyl or a 

 uranous band. In fact it may not be due to either of the two uranium salts. 

 The band is very similar to the one described under the oxidization of uranous 

 chloride in hydrochloric acid, only with the exception that the bands have very 

 different wave-lengths. 



OXIDIZATION OF URANOUS CHLORIDE IN HYDROCHLORIC ACID 



BY HYDROGEN PEROXIDE. 



It seems that the acid uranous aggregates are in general more stable 

 than the neutral aggregates. Hydrogen peroxide oxidizes the strongest acid 

 solutions. A spectrogram was, however, made of a neutral uranous chloride 

 solution, to which a large amount of concentrated hydrochloric acid had been 

 added, and to which increasing amounts of hydrogen peroxide were added. 

 The addition of the hydrochloric acid caused the uranous chloride bands to 

 be shifted about 100 Angstrom units towards the red. In other respects the 

 bands were not greatly changed, with the exception of the bands in the red. 



The uranous bands, on the addition of hydrogen peroxide, gradually 

 decreased in intensity without having their wave-length changed. At the 

 same time the uranyl bands appeared and, as is the case for strongly acid 

 solutions, the uranyl bands appeared quite sharp and intense. 



It may be supposed that in the case of the existence of acid aggregates 

 it would require a longer time for the oxidization to take place than in the case 

 where only neutral aggregates are present. It would be interesting to know 

 what the reaction velocities of these oxidization reactions are for the various 

 kinds of aggregates. 



It is a difficult matter to preserve uranous nitrate in the uranous condi- 

 tion. When uranyl nitrate is mixed with nitric acid and zinc is added, some 

 uranous nitrate is formed, but it is soon re-transformed into the uranyl con- 

 dition. This would indicate that uranous nitrate in water containing nitric 

 acid is unstable and is quickly oxidized. On the other hand, uranous chlo- 

 ride can be mixed with concentrated nitric acid and the uranous absorption 

 spectrum will be found to be entirely different from that of uranous chloride. 

 In this case the uranous salt will remain as such for at least a day or two 

 when kept at room temperatures. This may be explained by supposing that 

 the nitric acid aggregate of uranous nitrate is much more stable than the 

 salt itself. 



According to the law of mass action, if a nitrate is mixed with uranous 

 chloride, some uranous nitrate ought to be formed. To test the stability 

 of uranous nitrate, uranous chloride was dissolved in a solution of calcium 

 nitrate in water and methyl alcohol. Under these conditions both " water" 

 and "alcohol" bands appeared. This solution did not oxidize, but a black 

 precipitate was formed. This experiment could also be explained by suppos- 

 ing that the uranous nitrate in this solution existed in the condition of some 

 kind of an aggregate. The precipitate formed appeared to be similar to that 

 which is formed on heating a neutral uranous salt to the boiling-point. 



