52 



CONDUCTIVITY AND VISCOSITY IN MIXED SOLVENTS. 



In the 90 per cent mixture the results are perfectly regular, and, what is 

 surprising, a limiting value is reached at v = 157.67. 



In methyl alcohol the results are also regular, but there is no indication of 

 a maximum value for conductivity. The values found agree in most cases 

 very well with those of Carrara, whose results are also irregular (see fig. 12). 



SODIUM ACETATE IN MIXTURES OF ACETIC ACID AND WATER. 



The acetic acid froze at 15.47. From the tables of Riidorff it contained 

 in 100 parts by weight, 0.6 part by weight of water. Knowing the composi- 

 tion of the acid, the proper amounts to be used in making the mixtures could 

 be calculated. 



The acid was partially frozen and the liquid portion rejected. After 

 melting the solid acid the process was repeated. The specimen thus obtained 

 was used for the conductivities in the pure solvent. Owing to inevitable 

 exposure to the moisture of the air, it was not thought profitable to try to 

 remove the last traces of moisture. 



In this part of the problem new complications arose, since acetic acid in 

 aqueous solution conducts the current. 



The specific conductivity of the solvent (containing 25, 50, 75, and 100 per 

 cent by volume of acetic acid) was determined; then that of the solution 

 in question. The difference between the latter and the former was multiplied 

 by the volume to give the (apparent) molecular conductivity. 



The sodium acetate used was a specimen of the fused salt obtained from 

 Kahlbaum. It was dried for two days in an air-bath at 120 to 130. The 

 original solutions were made up by direct weighing. 



TABLE 29. Conductivity of sodium acetate. 



The results are seen to be irregular, and no final conclusions can be drawn 

 from them. In the 25 per cent mixture for v = 64, the molecular conduc- 

 tivity is apparently negative. This, of course, means nothing more than that 

 the specific conductivity of the solvent is greater than that of the solution. 



