OF SALTS IN ETHYL ALCOHOL AND WATER. 



95 



ISO 



of this is that the fluidities of a series of such mixtures of alcohol and 

 water tend also to become more nearly a linear function with rise in 

 temperature. 



In figure 39 we have plotted the conductivities of N/8 solution of 

 sodium iodide in the various solvents with respect to temperature, 

 making ordinates the conductivity and abscissas the temperatures. 

 From this we observe that the 

 temperature coefficients increase 

 slightly with rise in temperature, 

 with the exception of the 95 per 

 cent mixture and the pure alco- 

 hol. Further, the increase be- 

 comes smaller as we approach the 

 pure alcohol. The temperature 

 coefficients themselves also be- 

 come smaller as the percentage 

 of alcohol becomes greater. | 



The slight increase in the tern- | 

 perature coefficients in the water 

 end is doubtless due to the same 

 cause which produces an increase 

 in the temperature coefficients in 

 pure water, namely, a breaking 

 down of the hydrated ions with 

 rise in temperature. As was said 

 before, the salts of the alkali metal 

 are only very slightly hydrated; 

 therefore, the small increase in 

 temperature coefficients. 



Further, it is probable that since, with decrease in the amount of 

 water, the increase in coefficients becomes less until there is none in the 

 alcohol, the alcohol does not form alcoholates with these salts. 



Thus far we have discussed only the relations which exist between 

 the conductivities of the N/8 solutions. Reference to the curves for 

 the other dilutions, figures 41, 42, 43, 44, and 45, will, however, show 

 that the conclusions already arrived at also hold for them. 



One point which should be noted is that in the case of sodium iodide 

 there are distinct, though slight minima in the curves for N/128 and 

 N/1024 solutions, occurring at about the 70 per cent alcohol. This 

 phenomenon is not at all an unusual one, since practically everyone 

 who has determined the conductivities of other substances in alcohol- 

 water mixtures has found similar more or less pronounced minima. 

 Almost all previous work was in dilute solutions. 



10 20 30 40 50 60 70 80 



Percentage alcohol 



FIG. 45. 



90 100 



