108 CONDUCTIVITY AND VISCOSITY IN MIXED SOLVENTS. 



conductivity. In all cases these negative coefficients were found while working 

 at ordinary temperatures. 



Acetone and the alcohols are considered to be highly associated compounds 

 at ordinary temperatures. We have shown that the diminishing dissociating 

 power of a solvent with rise in temperature, must overcome the increasing 

 velocities of the ions in order to have a decrease in conductivity with rise in 

 temperature. Acetone and the alcohols are more associated at than at 

 25 and, consequently, their dissociating power is greater at the lower tempera- 

 ture. The ions, however, move faster at 25 than at 0. Since we have found 

 negative temperature coefficients, we believe that the effect due to diminishing 

 dissociation more than overcomes the effect due to the increasing velocities 

 of the ions. 



We think, nevertheless, that there is another factor which comes into play. 

 We are inclined to the view that the solvates which are formed in these cases 

 may be more stable at the higher temperature and, therefore, we should expect 

 t lie reaction which gave rise to them to be endothermic. At the dilution where 

 (lie temperature coefficient of conductivity is practically zero, these opposite 

 influences which affect conductivity become equal. The point where we have a 

 temperature coefficient which is practically zero corresponds to the maximum 

 in conductivity obtained by other workers at high temperatures. 



SUMMARY. 



(1) We have measured the fluidities of water, methyl alcohol, ethyl alcohol, 

 acetone, and binary mixtures of these solvents; also the fluidities of solutions 

 of lithium bromide in these mixtures. 



(2) We have also measured the conductivity of various concentrations of 

 lithium bromide and cobalt chloride, in the above-named solvents and mixtures 

 of these with one another. 



(3) The conductivities, in the case of mixtures of the alcohols with water, 

 exhibit a minimum. The same fact was found to be true in the case of 

 mixtures of acetone with water. This minimum in conductivity was found to 

 be more pronounced at the lower temperature, and has been shown to be 

 intimately connected with the minimum in fluidity observed in the above 

 mixtures. 



(4) The conductivities of lithium bromide, in mixtures of methyl and ethyl 

 alcohols, are what we should expect from the law of averages. The conduc- 

 tivity curves are nearly straight lines. In the case of cobalt chloride, in these 

 mixtures, there was a slight sagging of the curves. 



(5) In the case of lithium bromide, in mixtures of acetone with the alcohols, 

 the fluidities are what we should expect from the law of averages the 

 fluidity curves are straight lines. The same has been found to be true in the 

 case of the pure solvents. This indicates that acetone and the alcohols do 



