47 
1912-13.] The Absorption of Light by Inorganic Salts. 
for aqueous solutions of the same salts given in the fifth article, but also 
indicate that the copper band in the extreme ultra-violet has increased very 
much in height and breadth. 
The sulphates of nickel and cobalt were so nearly insoluble that no 
additional absorption could be noticed for alcohol in which the anhydrous 
salts had been immersed for days. The nickel salts were much less soluble 
than the cobalt salts. The original solutions of cobalt chloride and bromide 
were blue and purple-blue respectively, and after necessary dilution the 
former became purple and the latter almost transparent. The nickel 
chloride solution was very pale yellow, and the bromide solution pale 
Values of A for Solutions of Nickel Chloride. 
yellow-green. In the figures the curves for the chlorides and bromides are 
grouped according to the acid radicles. 
It was intended to make alcoholic solutions of the anhydrous nitrates. 
Unfortunately these salts seem to dissociate before complete dehydration 
takes place, and no satisfactory results could be obtained. 
In the curves shown there is no very distinct feature peculiar to either 
acid radicle, but the curves of the chlorides have more in common than 
those of the bromides have. It is to be noticed that in the case of the nickel 
salts there is an absorption band with its maximum about A = '410/a. 
This band also occurs in the aqueous solutions of nickel salts, as has 
been shown in the fourth article of the series. I made an effort to trace 
the effect of concentration on this band in the case of an aqueous solution 
of nickel chloride. As it was not possible with the cells at my disposal to 
work with a thickness of solution less than 1 mm., the height and position 
