SUMMARY. 41 



be true, it is probable, since those substances which dissociate dissolved elec- 

 trolytes also show in general a normal molecular weight for dissolved non- 

 electrolytes, that this breaking down of the polymerized molecule can be 

 accomplished best by another associated molecule. From this it follows that 

 the effect of mixing two associated solvents would be to lower the state of 

 association of one or both until a state of equilibrium is reached. Such a 

 mixture would be that of water and either methyl or ethyl alcohol, or a mix- 

 ture of methyl alcohol and ethyl alcohol. In these cases, since the molecules 

 are less associated than the constituents, we should expect dissolved electro- 

 lytes to show a conductivity lower than that required by the law of mixtures. 

 In every solvent with which we have worked this is exactly what has been 

 observed. In the mixtures of methyl alcohol and water, where the association 

 of the constituents is the greatest, the lowering of conductivity is also the 

 greatest, as would be expected. 



In support of the above view that one associated solvent can diminish the 

 association of another associated solvent, we have experimental evidence in 

 the results of freezing-point measurements. The molecular weights of the 

 alcohols in water, as determined by the freezing-point method, are normal; 

 while the surface-tension method of Ramsay and Shields shows, beyond 

 question, that the alcohols are associated compounds. 



The effect of temperature on the lowering of the conductivity is in accord 

 with the above suggestion. Since the effect of rise in temperature is to lower 

 the state of aggregation of an associated liquid, it would be expected that at 

 the higher temperature the influence of the solvents on each other would be 

 less than at the lower temperature. That such is the case can be seen by 

 comparing the results at with those at 25. 



The conclusion reached from this investigation, that one associated solvent 

 can diminish the association of another associated solvent, was subsequently 

 confirmed by the work of Jones and Murray. 1 They worked with water, 

 and formic and acetic acids, and determined the molecular weight of each in 

 the other by the freezing-point method. These, as is well known, are all 

 strongly associated substances when in the pure, homogeneous condition. 



Jones and Murray found that the molecular weights of these substances, 

 in the most concentrated solutions which could be studied, were always less 

 than the molecular weights of the pure substances as determined by the 

 method of Ramsay and Shields; 2 and, further, the molecular weights de- 

 creased in every case with increase in the dilution of the solution, as would 

 be expected from the law of mass action. Both of these facts point to the 

 same conclusion, viz, that one associated solvent breaks down the complex 

 molecules of another associated solvent into simpler molecules. 



'Amer. Chem. Journ., 30, 193 (1903). 

 2 Ztschr. phys. Chem., 12, 433 (1893). 



