ABSOEPTION SPECTRA OF SOLUTIONS. 



3B 



The next table gives similar results for solutions containing, per cu. cm., 0'00025 and 

 0-000125 of the salt: 



Graphical treatment of these results shows (1) that at the violet-ward end of the band 

 the two curves are very similar in form, but different in position, the strong solution 

 curve being nearer the violet by about two wave-length divisions, and (2) that at the 

 red- ward end the strong solution curve is much less curved than the weak solution 

 curve, and seems to cut the axis of intensities at a point about eight wave-length divi- 

 sions nearer the red. In other words increase of concentration in this case seems to widen 

 the range of complete absorption towards both ends, but more towards the red than 

 towards the violet. The penumbra of the violet end is simply displaced slightly towards 

 the violet, while that of the red end is both displaced towards the red and has its relative 

 intensity in different parts changed. 



The following table gives results similar to the above in the case of two still more 

 dilute solutions. They are especially interesting, because the observations extend right 

 across an absorption band. 



The fact that the intensity of the light in the second of these regions is, in the case 

 of both solutions, less than in the others, shews that somewhere between wave lengths 



