66 



THE ABSORPTION SPECTRA OF SOLUTIONS. 



THE SELECTIVE ACTION OF CHEMICAL REAGENTS ON SOLVATES. 



After photographing the effect of oxidizing the uranous salts to the uranyl 

 condition by the addition of hydrogen peroxide, it was natural to study what 

 effect the addition of other oxidizating agents would have upon the various 

 solvate bands. It will be remembered that the addition of hydrogen peroxide 

 caused the complete oxidization of the various solvates in the solution. It was 

 found that the action of the other oxidizing agents used was, in general, of a 

 more or less selective nature. 



A, plate 47, represents the absorption of a solution of uranous bromide 

 in 3.5 parts water and 6 parts methyl alcohol, to which was added calcium 

 nitrate in methyl alcohol, 1.2 normal. 



The addition of calcium nitrate causes a very great increase in the amount 

 of the general absorption of the short wave-lengths. This is to be especially 

 noticed in the last addition of the calcium nitrate. The most important thing 

 to be seen from this spectrogram is the rapid and almost total disappearance 

 of the water bands. The intensity of the alcohol bands changes very little, 

 if any, and it seems quite improbable that the uranous hydrate could have 

 been converted into uranous alcoholate without the alcohol bands increasing 

 very much in intensity. The natural conclusion is that the uranous hydrate 

 has been oxidized to the uranyl condition by the calcium nitrate. The original 

 film shows that in the third strip the two red uranous water bands have almost 

 the same intensity. This may mean that the uranous bromide has been 

 changed to some other salt. 



B, plate 47, represents the absorption of a solution of uranous bromide in 

 2 parts of water and 3 parts of methyl alcohol, the resultant solution being 

 about 0.12 normal. To this were added small amounts of a solution of sodium 

 perchlorate in methyl alcohol. It will be seen that the water bands decrease 

 in intensity as the sodium perchlorate is added, and that the longest wave- 

 length water band becomes more diffuse. The reason why the fifth strip is 

 vacant is on account of the formation of a precipitate. The precipitate was 

 not analyzed, but the spectrogram shows that the uranous hydrate has almost 

 entirely disappeared from the solution, while there is still present quite a 

 considerable amount of uranous alcoholate. This spectrogram is, therefore, 

 a good example of a case of selective precipitation of solvates. B, like A, 

 plate 47, indicates that there is a change in the constitution of the uranous 

 hydrate before it was precipitated. 



A, plate 46, represents the effect of the addition of potassium nitrate and 

 calcium nitrate to a solution of uranous bromide. In strip 1 we have the 



