IN ETHYL ALCOHOL. 69 



of this distillate being discarded. A few sticks of sodium hydroxide 

 added during the last day of heating insured the removal from the 

 distillate of any aldehyde which might have been present, and which 

 otherwise would have distilled over with the alcohol. It is possible, 

 by taking proper precautions in the manner of handling, to obtain by 

 such a method alcohol having a specific gravity of 0.78506, to within 

 the limits of experimental error, +0.00002. According to Circular 

 19 of the Bureau of Standards, alcohol with this specific gravity has 

 no water in it; that is, it is 100 per cent alcohol. The alcohol employed 

 in the conductivity measurements varied in specific gravity from the 

 value of 0.78506 to 0.78517, the latter containing 99.964 per cent 

 alcohol. The receiver for the distillate was a 6-liter Jena glass bottle. 

 The stopper was a three-holed paraffined cork. Through one hole 

 passed a siphon, through another an adapter with a glass stopcock, 

 and through the third a calcium chloride-soda lime tube also having a 

 glass stopcock. In this way the alcohol was well protected during 

 distillation from impurities in the air, and small quantities sufficient 

 for making up the solutions could be drawn off without exposing the 

 main supply. After weighing out the quantity of dried and purified acid 

 necessary to make a solution of the required normality, the acid was 

 washed off the watch glass or out of the weighing bottle into a funnel, 

 and then into a 200 c.c. Jena flask which had previously been thoroughy 

 washed with water, and then with some of the alcohol with which the 

 solution was to be made up. The flask was filled to the neck with 

 alcohol and shaken until all the acid had dissolved. It was finally 

 hung in a 25 thermostat-bath until temperature equilibrium was 

 reached, and then filled to the mark. In the meantime a conductivity- 

 cell which had been thoroughly washed the day before and in which 

 pure alcohol had been allowed to stand over night, was dried with 

 filtered dry air. It was then rinsed several times with portions of the 

 solution which had just been made up, and finally nearly filled with 

 this solution introduced as shown in figure 23. A little carbonate is 

 formed by opening in this way to the air, but it is a very small quantity, 

 and in the course of a few days is entirely precipitated to the bottom 

 of the bottle. T and T f are filled with a mixture of calcium chloride 

 and soda-lime to protect the alcoholic solution when the stopcocks 

 S and S are opened. The stoppers in T and T' are of cork and are 

 thoroughly paraffined. A system such as this remains protected from 

 the air for a period of several months. 



The alcoholic solution, in course of time, becomes colored slightly 

 yellow, but its alkaline concentration is apparently not changed, as can 

 be seen by comparing titrations made against a standard acid in 

 February and again in May: 



On Feb. 25, 10 c.c. of standard acid = 8.87 c.c. of alkali. 



On May 7, 10 c.c. of standard acid = 8.87 c.c. of alkali. 



