SOLVENTS. 127 



measured, was introduced into the viscometer. The liquid was raised to the 

 mark above the bulb by means of air-pressure, the air being dried with 

 calcium chloride or with concentrated sulphuric acid. The pressure was then 

 released by means of a Mohr pinchcock on a thick-walled rubber tube. The 

 time of flow through the capillary tube was determined by means of a stop- 

 watch, reading to two-tenths of a second. 



In order to calculate the viscosity, it is necessary to measure the specific 

 gravity of the solution. For this purpose we used the pycnometer employed 

 by Jones and Bingham * in their work. The pycnometer was so constructed 

 as to allow the large expansion of the alcohols and acetone, and avoid loss by 

 evaporation. 



A large battery-jar, filled with finely crushed ice moistened with water, 

 was used for the zero-bath. The ice was frequently renewed to keep the 

 temperature constant. For the 25 bath a beaker holding 5 liters was em- 

 ployed. The bath was stirred by means of a hot-air engine, the temperature 

 being kept at 25. It did not vary more than a tenth of a degree. 



SOLVENTS. 



WATER. 



The water used in this work was purified according to the following method : 

 Ordinary distilled water was first distilled from potassium dichromate and 

 sulphuric acid. This water was redistilled from acidified potassium dichro- 

 mate and then from barium hydroxide. Water thus purified gave a conduc- 

 tivity of IxlCT 6 at and from 1.5 to 2.0 X 1CT 8 at 25. 



METHYL ALCOHOL. 



The methyl alcohol used was the best commercial article that could be 

 obtained. It was first boiled with calcium oxide for several days, then dis- 

 tilled and allowed to stand over anhydrous copper sulphate for weeks. Be- 

 fore use it was distilled from the copper sulphate, using a Linnemann frac- 

 tionating head. Care was always taken to keep it free from moisture. The 

 first and last portions of the distillate were discarded. The mean value of 

 the conductivity was 1.1 x KT 6 at and 2 x lO"" at 25. 



ETHYL ALCOHOL. 



The ethyl alcohol was the best article commercially obtainable, and was 

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

 mean value of 0.6 x 1CT 8 at and 1.5 x 10 ~" at 25. 



ACETONE. 



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

 with a Linnemann fractionating head. Its conductivity was 0.4 X 10~* 

 at and 0.6x10^ at 25. 



1 Amer. Chem. Journ., 34, 495 (1905). 



