SOLVENTS. 83 



SOLVENTS. 



WATER. 



The water was purified by the method of Jones and Mackay, 1 and had a 

 conductivity of 1 X 10~ 6 at 0. 



METHYL ALCOHOL. 



The methyl alcohol was the best commercial article obtainable. It was 

 boiled with calcium oxide for a day, distilled, and allowed to stand over 

 anhydrous copper sulphate for a long time. Before use it was distilled, 

 using a Linnemann fractionating head. Precautions were taken against ab- 

 sorption of moisture. The first and last portions of the distillate were 

 discarded, giving a liquid which boiled constantly at 66. The mean value 

 of the conductivity was 2 x 10~ 6 at 25. 



ETHYL ALCOHOL. 



The ethyl alcohol was the best commercial alcohol obtainable. It was 

 purified in the same manner as the methyl alcohol. Its conductivity had a 

 mean value of 2 x lO" 6 at 25. 



ACETONE. 



The acetone was dried over fused calcium chloride for weeks and distilled 

 with a fractionating head as above. Its conductivity was 0.6 X 10~ 6 . 



CONDUCTIVITY MEASUREMENTS. 



In all determinations of conductivity at least three different resistances 

 were used, and the values given are the mean. However, if the readings did 

 not agree to 0.1 of 1 per cent, they were usually repeated. The constants 

 of the cells were checked at frequent intervals. The cells were not allowed to 

 remain in contact with the solution when not in use, nor to remain empty 

 after being dried out with alcohol and ether. In the former case, small quanti- 

 ties of salt were found to be slowly absorbed, and in the latter acetic acid was 

 formed by the action of the platinum on the alcohol or ether in the presence 

 of air. When not in use the cells were filled with pure distilled water. 



A N/50 and a N/500 solution of potassium chloride were used in determin- 

 ing the cell constants. The conductivity of the former was taken as 129.7 

 at 25. The value of the latter was determined several times in different cells. 

 The mean value obtained agrees well with the interpolated values of other 

 observers. 



The temperature coefficients are obtained by dividing the increase in the 

 conductivity per degree by the conductivity at the lower temperature. 



1 Ztschr. phys. Chem , 22, 237 (1897). Amer. Chem. Journ., 19, 91 (1897). 



