122 A STUDY OF THE ABSORPTION SPECTRA. 



of hydrogen peroxide, uranyl nitrate, and potassium hydroxide (a mini- 

 mum amount of the hydroxide), golden yellow needles crystallize out having 

 the composition (NaO,) 2 U0 4 .8H 2 0. 



Very little work has been done up to the present on the absorption 

 spectra of uranous salts, largely because of their very unstable character 

 iu solution. J. Formanek ' describes the absorption spectra of uranous 

 chloride. This was prepared by adding a little zinc and hydrochloric acid 

 to a uranyl chloride solution. He found that the spectrum changed as the 

 uranyl chloride was being reduced. A very strong band was found at 

 X 6507. The other bands, eleven in number, were XX 6722, 6367, 6165, 6030, 

 5782, 5497, 523S, 5064, 4962. 4840, and 4519. 



A similar method has been used by the writers. The uranous nitrate, 

 sulphate, and chloride were formed by adding the corresponding acid to a 

 solution of the uranyl salt containing some zinc. The uranous chloride 

 and sulphate were quite stable in solution, remaining reduced for weeks. 

 Uranous sulphate crystallizes out from solution as U(S0 4 ) 2 .9H 2 0. Solu- 

 tions in alcohol can be reduced just as easily as solutions in water. Ura- 

 nous nitrate was found to be very unstable. At the present writing a number 

 of spectrograms have been made, and much more work will be done on 

 these uranous salts and on the absorption spectra of the various oxides. 

 It has already been found that uranous chloride 2 has very different spectra 

 in different solvents. 



Uranous Chloride in Water. 



A solution of uranous chloride in water was made in the usual way. 

 This solution was of a dark green color even when very dilute. When 

 sufficiently dilute most of the uranous salt came down as a precipitate 

 after standing for several days. The solution was examined spectro- 

 scopical y it being practically colorless to the naked eye. The absorption 

 spectra corresponded closely to that of the uranyl chloride bands of water. 

 e, f, and g appear with considerable intensity, while the other bands are 

 very weak; e consisting of two bands of about equal intensity and very 

 close together. The wave-lengths of the bands are approximately as fol- 

 lows: X 5030 (weak) ; a, X 4910; 6 (very weak), X 4790; c (very weak), X 4550; 

 d (very weak), X 4420; e, XX 4305, 4270; f, ,14150, and g, X 4020. 



The spectrogram (Plate 84, A) represents the absorption of a 0.17 

 normal solution of uranous chloride in water. Starting with the first strip 

 the depths of cell are 1.2, 2, 4, 8, 16, and 32 mm. For the first three strips 

 the exposures were for 3 minutes to the Nernst glower for all the spectrum; 

 3 minutes to the ultra-violet, and 1 minute to the spark. The other three 

 strips were exposed to the Nernst glower for 3 minutes. The slit-width was 

 0.15 mm. and the current in the glower 0.9 ampere. No exposure to the 

 ultra-violet was made for the upper strips, as it was considered that this 

 region would be entirely absorbed. The spectrogram shows, however, that 

 this would not have been the case. 



1 Phys. Rev., 29, 555 (1909) ; 30, 279 (1910;. 2 Ibid. 



