VOLUME CHANGES IN THE PROCESS OF SOLUTION. 99 



in total volume. In the case of a mixture of alcohol and 

 water which is already condensed, the addition of the 

 solute would be expected to have a smaller effect. The 

 observed value of v s would therefore be greater in such 

 a mixture than in either of the simple solvents. 



It follows from the results given above that the maximum 

 solution volume of a solute is not always found in the 

 mixture which has undergone the maximum contraction in 

 its preparation. Thus in the case of carbamide, the maxi- 

 mum solution volume occurs in a 32 per cent, alcohol 

 mixture, whereas the maximum specific contraction 

 (between water and alcohol) takes place when the mixture 

 contains about 44 per cent, alcohol. The position of the 

 observed maximum contraction depends on the relative 

 volumes of the different molecules concerned. 



