8 INTRODUCTION. 



is sufficiently evident. Each solvent, highly associated in the pure condition, breaks 

 down the association of the other, as shown by Jones and Murray, so that the 

 resulting mixture is composed of a greater number of smaller molecules in a given 

 volume. Simple molecules would probably have greater chemical activity than the 

 more complex ones, and would combine with the solute to a greater extent. The 

 effect of heat on such solvates would be greater with increasing complexity of the 

 solvate. In connection with this breaking down of the solvents into simpler aggre- 

 gates, the total internal frictional surface would be increased, and an increase in 

 viscosity is the result. Again, in terms of Dutoit and Aston's hypothesis, the dis- 

 sociating power of such a mixture should be less than that of the pure solvents, and 

 this is an important factor in determining the conductivity minimum, as pointed 

 out by Jones and Bingham. It is noticed that in these mixtures of minimum 

 fluidity there is a smaller increase of conductivity with dilution than in the other 

 mixtures, and this is, of course, a consequence of the view here adopted. 



In a second communication, 1 Jones and Veazey took up a study of solutions of 

 tetraethylammonium iodide Walden's " Normalelektroly t " in mixtures of water, 

 the alcohols, and nitrobenzene. The latter is a solvent of a type entirely different 

 from the hydroxy-compounds or acetone, and it was important to know whether the 

 relations previously found would hold for mixtures containing this substance. 



In mixtures of both the alcohols with water, tetraethylammonium iodide shows a 

 well-defined conductivity minimum in the neighborhood of the 50 or 75 per cent 

 mixtures at both and 25. In mixtures of the alcohols with each other, no min- 

 ima appeared, although the values are less than the averages. Mixtures of methyl 

 alcohol and nitrobenzene behaved similarly, but mixtures of ethyl alcohol and nitro- 

 benzene gave a maximum in the solutions containing 25 per cent of the latter. The 

 fluidity curves of mixtures of water and the alcohols have already been sufficiently 

 treated, and here, as before, the conductivity curves follow them closely. The 

 same general relations appear in mixtures of nitrobenzene and the alcohols. A 

 fluidity maximum shows itself in mixtures containing 25 per cent of nitrobenzene, 

 with either alcohol, and at and 25. Hence, the conductivity curves, in the case 

 of nitrobenzene-ethyl alcohol mixtures at least, follow the fluidity curves, and the 

 variation with nitrobenzene-methyl alcohol is slight. 



It has now been shown that for all the solvents worked with, it is practically a 

 constant phenomenon for conductivity curves to have the same general char- 

 acteristics as fluidity curves. On the other hand, we must not lose sight of the fact 

 that several well-marked exceptions have been found, and notably in mixtures 

 containing acetone. Here the fluidity curves for water-acetone have minima, and 

 for acetone-alcohol are nearly straight lines, while the conductivity curves for lithium 

 bromide, lithium nitrate, cobalt chloride, and calcium nitrate show pronounced 

 maxima, or pseudomaxima. Moreover, the values of the molecular conductivities 

 in acetone are abnormally low, except for lithium salts. 



In the work of Walden, 2 already referred to, it was found that the product of the 

 limiting molecular conductivity of tetraethylammonium iodide and the viscosity 

 of its infinitely dilute solutions is nearly a constant for about thirty organic solvents 



iZeit. phya. Chem., 62, 41 (1908). *lbid., 5S, 207 (1906). 



