DISCUSSION OF EVIDENCE. 163 



The first investigation was carried out by Lindsay. 1 He worked 

 in water, in methyl, ethyl, and propyl alcohols, and in mixtures of 

 these solvents with one another. He found, in certain mixtures of the 

 alcohols with water, that the conductivity of the dissolved salt was 

 less than in the pure alcohol. The conductivity curves in mixtures 

 of methyl alcohol and water passed through well-defined minima, and 

 a conductivity minimum was also frequently found in mixtures of 

 ethyl alcohol and water. 



A possible explanation of the results in mixtures of the alcohols with 

 water is that each solvent diminishes the association of the other. 

 Since the dissociating power of a solvent is in general greater the larger 

 its own association, it follows that whatever would decrease the asso- 

 ciation of a liquid would decrease its power to dissociate electrolytes 

 dissolved in it. The question is, does one associated liquid diminish 

 the association of another associated liquid? 



An associated liquid tears down the molecules of an electrolyte 

 dissolved in it, into simpler parts or ions; and it might be expected 

 that such a liquid would tear down the molecules of another associated 

 liquid, a non-electrolyte, not into charged parts or ions, but into 

 simpler molecules. The alcohol and water are associated liquids, as 

 has been shown by the surface-tension method of Ramsay and Shields. 2 

 Do these diminish the association of one another? 



That this is the case was shown by Murray. 3 He worked with the 

 associated liquids, water, formic acid, and acetic acid. He determined 

 the molecular weight of each of these liquids in the other two, and 

 found that their molecular weights became smaller the more dilute 

 the solutions. This showed that the solvent, i. e., the liquid present 

 in the larger quantity, was tearing down the molecular complexes of 

 the dissolved liquid or the one present in smaller quantity. 



That the diminution in the association of one associated liquid by 

 another associated liquid was true, was shown for the above-named 

 substances and made highly probable for others. 



That this was not the entire explanation of the nature of the con- 

 ductivity curves in mixtures of certain alcohols with w T ater, was brought 

 out by the next investigation in this field, carried out here by Carroll. 4 

 He compared the conductivity curves of electrolytes dissolved in 

 these solvents, with the fluidity curves of the mixtures of the two liquids 

 in question, and found that the two sets of curves were very similar. 

 The minima in the two cases occurred in the same mixture of the two 

 liquids. A careful comparison of the two sets of phenomena led us 

 to conclude that the conductivity minima are largely due to the dimin- 

 ished fluidity which takes place on mixing the two solvents. The 

 diminished fluidity, or increased viscosity, would cause the ions to 

 move more slowly, and hence decrease the conductivity. 



r. Chem. Journ., 28, 329 (1902). 3 Amer. Chem. Journ., 30, 193 (1903). 



2 Zeit. phys. Chem., 12, 433 (1893). 4 Ibid., 32, 521 (1904). 



