128 



Conductivities and Viscosities in Pure and in Mixed Solvents. 



of hydrochloric acid in alcohol first decreases with increasing percentage 

 of water, then passes through a minimum at 77 = 2, and finally begins to 

 increase again. JU M behaves in a similar manner. 



Using the value 89 for /i , and combining with it the values of /* 

 obtained for the different water concentrations (77) , Goldschmidt solved 

 equation (III) for r and u u', and obtained the constants 0.0583 and 

 42.7 respectively. The high value of u u' shows that the complex 

 ion (H 2 0, H) + travels much more slowly than the free or the alcoholated 

 hydrogen ion. The constancy of r and u u' is evidence in favor of 

 the correctness of the reasoning by which the equation was developed. 



In order to determine the limit of applicability of the constants 0.0583 

 and 42.7, Goldschmidt used these constants to recalculate the values 

 of /*,. He found satisfactory agreement between the calculated values 

 and those obtained experimentally, so long as the percentage of water 

 (77) in the alcohol did not exceed unity. (Beyond this point there was 

 a lack of agreement, caused no doubt by the influence of water upon 

 the migration velocities of the ions.) Thus, Goldschmidt showed that 

 by means of the constants 0.0583 and 42.7 the effect of water on the 

 conductivity of alcoholic solutions of strong acids could be calculated. 



TABLE 73. 



Desiring to adduce further evidence bearing on his theory, Gold- 

 schmidt took up a study of the conductivity of Sulphosalicylic acid. 

 He found the behavior of this acid to be entirely analogous to that of 

 hydrochloric. The molecular conductivity in alcohol was influenced 

 to the same extent by the addition of water, and the amount of this 

 influence could be calculated with the aid of the constants 0.0583 and 

 42.7. The limiting conductivity in absolute alcohol (/i ) was estimated 

 both from the IJL^ value of the sodium salt (by the method of Ostwald) , 

 and from the ^ values of the free acid in aqueous alcohol (by means of 

 equation III), and the figure obtained was the same (83) in both cases. 



Satisfied with the results of his investigations upon the stronger 

 acids, Goldschmidt next turned his attention to the weaker picric, 

 trichloracetic, trinitrobenzoic, trichlorbutyric, dichloracetic, and sali- 

 cylic. He observed that in every case the molecular conductivity 



