JOURNAL 
OF THE 
Flisha Mitchell Scientific Society. 
FIFTEENTH YEAR—PART ONE. 
1898. 
THE NATURE OF THE CHANGE FROM VIOLET 
TO GREEN IN SOLUTIONS OF CHROM- 
IUM SALTS. 
By F. P. VENABLE AND F. W. MILLER. 
It is a well-known fact that solutions of certain chrom- 
ium salts which are violet in color become green on heat- 
ing. This has been especially noticed in the case of the 
chrome-alums and of the sulphate, but is also true of the 
nitrate, chloride, and acetate, in fact, of all the soluble 
compounds of chromium. A reverse reaction also takes 
place and all of these solutions made green by heating 
become violet again on standing, the nitrate, chloride, 
and acetate very rapidly, the sulphate and alums slowly, 
and often only after prolonged standing. It is quite rea- 
sonable to suppose that these changes are caused by sim- 
ilar reactions in the case of various salts, and that there 
is one explanation for all. 
A large number of explanations have been offered by 
various investigators. In fact it is surprising to find 
how many have been drawn to investigate these changes 
and what an amount of work has been done upon them. 
Perhaps the difficult nature of the problem has been the 
great source of attraction. Fischer’ and Jacquelain’ 
1Kastner’s Archiv., 14, 164. 
2 Compt. rend., 24, 439. 
