ABSORPTION SPECTRA OF SOLUTIONS. 41 



Uranium salts. In oue case in which he compared solutions containing respectively 569, 

 and less than 0"1G6, grni. per cu. dm., he Ibviud the bauds of the strong solution (whose 

 concentratiou it will be noticed was very considerable) nearer the violet than in the 

 weak solution. In another in which the concentrations were 29 and 0065 gm. per cu. 

 dm. respectively, he found the bands to occupy the same positions in the spectra of both, 

 but the boundary of the complete absorption of the violet end to be very slightly nearer 

 the violet in the strong than in the weak solution. In a third case in which the concen- 

 trations were 320 and 0'128 grm. per cu. dm., he found the spectra undistinguishable. 

 It would be interesting to compare with these results those obtained by Morton ' in his 

 observations of the absorption spectra of solutions of salts of the same metal. But I have 

 not access to his paper. The only account of it which I have seen says simply that he 

 found that elevation of temperature in general displaces the absorption bands towards 

 the red, but that in some cases no displacement is produced. I do not even know whether 

 or not both observers made experiments on the same salts. In the meantime, therefore, 

 I cannot determine whether a comparison of the results of these observers would confirm 

 or throw doubt upon the conclusions reached above. 



'■ ' Fortschritte_der Phy.sik,' Jahrgang xxix, p. 4'24. 



Pec. Ill, 1891. 6. 



