THEORY OF CONCENTRATED SOLUTIONS. 



U9 



deviation of the property-composition curve from the straight 

 line is proportional to the amount of compound formed. 



Hence the maximum deviation of the property-composition 

 curve fro'm the straight line must occur at that composition of 

 the mixture which gives the composition of the compound formed. 



In order then to decide whether chemical combination occurs 

 on mixing two liquids, it is sufficient to determine the value of 

 the specific or molecular volume, refractive index, optical rota- 

 tion, etc., for mixtures of various compositions, and find at what 

 composition the deviation from the straight line is a maximum. 





Percentage of pyridine. 

 Fig. 3. 



Numerous examples could be given to show the applicability 

 of this deduction. At present I will confine myself to very few. 



In Fig. 2 are plotted the deviations from the mixture law of 

 ethyl-alcohol — water mixtures as regards specific volume. The 

 actual experimental figures are not given, but are to be found in 

 the transactions of the Faraday Society, 1912, where a somewhat 

 more detailed discussion of this subject is given. A sharp maxi- 

 mum in the deviation curve occurs at 46% alcohol. 

 C,,H,.p. 3 H 2 = 46% alcohol. 



