140 



THEORY OF CONCENTRATED SOLUTIONS. 



The viscosity deviation curve also gives a maximum at 46^/0 . 



Similarly Fig. 3 gives the contraction on mixing and the 

 viscosity deviation from the mixture law • for mixtures of 

 pyridine and water. A maximum deviation occurs at 68.5^ 

 pyridine. 



C 5 H 5 N. 2H 3 = 68-6%. 



In Fig. 4 are plotted the actual viscosity-composition curves 

 and the deviation curves for mixtures of henzene, acetic acid and 

 lactic acid — water. 



The actual viscosity-composition gives no indication of the 

 formation of a compound, but maximum deviation from the 

 mixture law occurs at 39.5% benzene and 72% lactic acid respec- 

 tively. 



C,.H . 2C 2 H 3 2 = 39'4% benzene 

 C 3 H 6 3 . 2H 2 - 71 -5°,', lactic acid. 



In all these cases maximum deviation occurs at a composi- 

 tion which represents as exactly as experimental accuracy permits 

 simple molecular relationships between the constituents of the 

 mixture. 



