254 il/?' Purvis, The influence of dilution on the colour 



and both general absorptions were greater here than those in the 

 154 solutions. 



The shift towards the red end of the bands of the 5 solutions 

 was much better marked when compared with those of the 

 310 solutions than those of the 154 solutions. 



The solutions were allowed to stand as before in the dark and 

 the light for two days longer and they were again examined. 



N. Zinc permanganate in dark 1 -, ^ . i , • 



1 ^ 1° • ,. 1, h 154 solutions, 



do. do. m light J 



do. do. in dark 5 solution. 



There was a very doubtful increase in the general absorption 

 of the 154 solutions as compared with the previous observations in 

 L, otherwise the differences in the appearances of the bands were 

 very like those in the previous observations. There was no 

 difference in the width and appearances of the bands of the 

 solutions kept either in the light or dark ; the bands 2 and 3 were 

 narrower in these solutions than in the 5 solution, whilst the 

 bands 4 and 5 were very slightly wider. 



0. Zinc permanganate in dark 1 qi rj i f 

 do. do. in light J 



do. do. in dark 5 solution. 



There appeared to be but a very slight increase in the general 

 absorption of the 310 solutions as compared with the previous 

 observations ; the bands 1, 2 and 3 were narrower than the 

 corresponding bands in the 5 solution, the band 2 being the most 

 marked in this respect, whilst bands 4 and 5 were slightly wider 

 than the corresponding bands in the 5 solution. 



The shift of the bands towards the red end in the 5 solution 

 was distinct as compared with their positions in the 310 solutions. 



The observations indicate that similar changes take place in the 

 zinc permanganate solutions as in those of barium and potassium; 

 and that light accelerates the changes. 



General conclusions. 



The results prove that, during the time of the observations, 

 (1) in the stronger 5 solutions there did not appear to be any 

 marked change in the ordinary colour nor in the absorption bands 

 of the permanganates; (2) in the 154 solutions there were con- 

 siderable changes in the colour which slowly turned to a rose red 

 or reddish brown one accompanied by changes in the width of the 

 absorption bands 1, 2, 3, 4 and 5 and an increase in the general 

 absorption; (3) in the 310 solutions the changes in the colour 

 were more marked and a brownish yellow colour was developed 



