12 



PROCEEDINGS OF THE AMERICAN ACADEMY. 



Secondly, at 30°, in the presence of sucrose and glucose, the violet 

 solution is converted at least in part into the green. 



From these experiments it seemed probable, since the effect of the 

 sugar could hardly be great, that the relation between the green and 

 the violet solution is a changeable one, depending upon the temperature, 

 and attaining at each temperature a definite equilibrium. It seemed 

 highly desirable to test this conclusion by suitable experiments. 



Accordingly a fourth-molar violet and a fourth-molar boiled green 

 solution, both free from sugar, were placed in a thermostat at 30°. 

 After five days, 5 c.c. of each solution was removed by means of a 

 pipette, mixed with two portions of 20.00 c.c. each of a sugar solution, 

 and followed by means of the freezing point. Unfortunately the supply 

 tube containing the green solution was then broken, so that a new one 

 was placed in the thermostat. At the end of twelve days for the violet 

 and seven days for the new green solution, new portions were mixed with 

 sugar ; again eight days afterward this process was repeated, and yet 

 again after nine days more. There are given below the figures of the 

 first two and the last two of these freezing point determinations ; the 

 others confirm the verdict of these and are omitted to economize space. 

 For the same reason only the additional depressions of the freezing 

 point are given; — these were found in the manner already described. 

 The results are plotted on the diagram (curves C, D, ¥^, F, G), which 

 gives also in dotted lines those of the previous series. 



Equilibrium of Green and Violet Solutions. 

 Depression of Freezing Points of Solutions Maintained at 30°. 



