THE NEW THEORY OF SOLUTIONS. 



173 



SOLUTIONS IN ACETIC ACID. 



For the solutions given, the value of the molecular rise 

 steadily alters as^' increases. In the most dilute solutions, 

 however, the values for different substances dissolved in the 

 same solvent are practically the same. 



Influence of the chemical nature of the solvent. — In 1882, 

 Raoult concluded that F, the molecular lowering, is pro- 

 portional to M, the molecular weight of the solvent. The 

 data given by him in 1884 to support this statement are 

 contained in the following table, where F is, for each 

 solvent, the mean value obtained by the use of different 

 dissolved substances. 



The values of F/M do not differ widely from 0-63, and 

 Raoult therefore stated the rule that " when one molecule of 

 a substance is dissolved in one hundred molecules of any 

 solvent, the freezing-point of the latter is lowered by 0*63° ". 

 In order to make water harmonise with this rule, the above 

 table shows that its molecular weight has to be taken as 

 4x18, the molecular formula of liquid water being supposed 

 to be 4H0O. The value of F for water had been derived 



