CHAPTER XI. 



URANIUM SALTS. 



Absorption spectra of uranium compounds. Absorption spectra of uranyl 

 chloride. Absorption spectra of uranyl nitrate. Absorption spectra of uranyl 

 bromide, sulphate, and acetate. Spectrophotography of the chemical reac- 

 tions of uranyl salts; conductivity data. The phosphorescent and fluorescent 

 spectra. Absorption spectra of uranous salts. 



THE ABSORPTION SPECTRA OF URANIUM COMPOUNDS. 



There are quite a large number of spectra of the various compounds 

 and decomposition products of the element uranium. The absorption 

 spectra consist chiefly of the banded spectra of the uranyl and uranous 

 compounds. Uranyl salts in solution are yellow and their absorption 

 spectra consist of a broad band of general absorption in the ultra-violet, 

 which extends more and more into the region of longer wave-lengths as the 

 amount of uranyl salt solution in the beam of light is increased. The edge 

 of this absorption band as it gradually advances through the violet and 

 into the blue shows several diffuse bands about 50 Angstrom units wide and 

 about 100 Angstrom units distant from each other. These comparatively 

 fine bands, about twelve in number, are weak, having very diffuse edges, 

 and can be photographed only when they lie near the edge of the general 

 absorption band. Among those who have carried out investigations 

 upon the absorption spectra of these compounds may be mentioned: 

 H. Oeffinger, 1 H. Becquerel, 2 W. Boehlendorff, 3 O. Knoblauch, 4 E. Deussen, 8 

 Formanek, 6 Hartley, 7 Houstoun and Russel, 8 Jones and Strong, 9 Strong, 10 

 and others. 



In the discussion of the uranyl bands it will be found convenient to 

 designate them by the letters a, b, c, d, etc., the band a being of the greatest 

 wave-length, and the wave-lengths of the other bands gradually decreasing. 

 In general it will be found that this classification is very useful, and upon 

 general observations it might be supposed that each band had its origin 

 in a particular vibration of the vibrating system. But at low temperatures 

 these bands are found to consist of a number of much finer bands, and the 

 absorption spectra become very complicated indeed, so that it is clear 

 that changes which are observed at ordinary temperatures may be due to 

 relative changes in the groups of five bands composing the larger bands, 



1 Ueber die Lichtabsorption der Uransalze, Inaug. Diss., Tubingen, 1866. 



2 Ann. Chim. Phys., (6) 14, 170-257 (1888). 



3 Inaug. Diss., Erlangen, 1890. 

 Wied. Ann., 43, 738-783 (1891). 

 5 Ibid., 66, 1128-1148 (1898). 



8 Die qualitative Spectralanalyse anorg. Korper, Berlin, 1900. 



7 J. Chem. Soc, 83, 221-246 (1903). 



8 Proc. Roy. Soc. Edinb., 29, n, 68. 

 Phys. Zeit., 10,499(1909). 



10 Phys. Rev., 29, 555 (1909); 30, 279 (1910). 



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