SPECTROPHOTOGKAPIIY OF CHEMICAL REACTIONS. 61 



Uranyl chloride, hydrochloric acid, and potassium nitrate were mixed in 

 water and methyl alcohol, and zinc was added. The reduction took place easily 

 and the resulting uranous salt remained stable. It is probable that in this 

 case, also, more stable aggregates than neutral uranous nitrate were formed. 

 As a reciprocal reaction, uranyl nitrate, aluminium chloride, and hydrochloric 

 acid (in small quantity) were dissolved in water and zinc added. A stable 

 solution of a uranous salt, probably largely chloride, was formed. In this 

 case very little uranyl nitrate existed in the solution after the aluminium 

 chloride and hydrochloric acid were added. These three experiments would 

 then indicate that there is probably but little oxidization of uranous chloride 

 to the uranyl salt under these conditions. 



THE OXIDIZATION OF URANOUS SULPHATE. 



The preparation of concentrated aqueous solutions of uranous chloride 

 and uranous bromide is not difficult, using the method of reduction of the 

 corresponding uranyl salt with nascent hydrogen. A concentrated aqueous 

 solution of uranous sulphate can be obtained in a similar manner, but on 

 standing almost all of the uranium is precipitated. The presence of sulphuric 

 acid, however, enabled us to prepare a far more concentrated solution of 

 uranous sulphate, and this was quite stable. 



A solution of uranous sulphate was prepared by reducing uranyl sulphate 

 with nascent hydrogen. The precipitate formed was partly dissolved in water. 

 The aqueous solution of uranous sulphate thus prepared was approximately 

 0.1 normal, and was fairly stable when kept in ground-glass stoppered bottles. 

 When exposed to the air it oxidized slowly to the uranyl condition. The 

 addition of methyl alcohol, ethyl alcohol, or acetone to the aqueous solution 

 of uranyl sulphate precipitated some of the salt. 



A spectrogram, B, plate 35, shows the oxidization of an aqueous solution 

 of uranous sulphate to uranyl sulphate, by the addition of an aqueous solution 

 of hydrogen peroxide. 



The original film shows quite a large number of the uranyl bands. The 

 wave-lengths of the uranyl bands seem somewhat greater than those of uranyl 

 sulphate solutions made from the chemically pure salt. This is probably due 

 to the presence of a considerable amount of zinc sulphate. In addition to the 

 regular uranyl sulphate bands there is present quite a fine and weak band at 

 X 5100. This band does not seem to vary to any considerable extent from 

 strip to strip, and it is difficult to say whether it is a uranyl or a uranous band. 



THE OXIDIZATION OF URANOUS BROMIDE BY HYDROGEN PEROXIDE. 



An aqueous solution of uranous bromide is oxidized by hydrogen peroxide 

 in the same way that uranous chloride is oxidized. The absorption spectra of 

 the bromide and chloride are quite similar for the uranyl and the uranous salts. 



A solution of uranous bromide in ethyl alcohol is oxidized by hydrogen 

 peroxide. In the case photographed the alcoholic solution had a very great 

 ultra-violet, violet, and blue absorption after the oxidization had taken place. 



B, plate 44, represents the oxidization of a glycerol solution by the addition 

 of hydrogen peroxide. In addition to a few of the uranyl bands, the character- 

 istic uranous glycerol bands consist of a wide diffuse band atX 4400 and a strong 



