130 Conductivities and Viscosities in Pure and in Mixed Solvents. 



The receiver for the distillate was a 6-liter Jena glass bottle, having a 

 three-holed paraffined cork as stopper. Through one hole passed a 

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

 the third a calcium chloride-soda lime tube. 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. By exercising extreme care 

 it is possible by this method to obtain alcohol having a specific gravity 

 of 0.78506 to within the limit of error 0.00002. According to Circular 

 19 of the Bureau of Standards such alcohol is pure. The alcohol 

 employed in the conductivity measurements varied in specific gravity 

 from 0.78506 to 0.78517, the latter containing 99.964 per cent alcohol. 



The organic acids were obtained from Kahlbaum and Schuchardt. 

 The same methods of purifying them were employed as when the con- 

 ductivities of these acids were determined in aqueous solution. 1 After 

 purification they were carefully dried in a vacuum desiccator containing 

 sulphuric acid. Whenever practicable the melting-points of the acids 

 were taken as one criterion of purity. 



Aqueous solutions of ammonia were used for titration purposes, since 

 ammonia had been found by Wightman, Wiesel, and Jones 2 to give the 

 most satisfactory results. These solutions were prepared as follows: 

 Concentrated ammonia was heated and the gas which was given off 

 passed first over sodium hydroxide, which collected a large part of 

 the water-vapor and any carbon dioxide; then over sodium, which 

 absorbed the remainder of the water- vapor; and finally into a weighed 

 quantity of conductivity water in a measuring flask, until the amount 

 necessary to make a 0.1 N solution was dissolved. By diluting this 

 solution with conductivity water any desired strength of ammonia 

 could be obtained. The normality of each solution employed was 

 determined by titration against standard sulphuric acid. 



Corallin (rosolic acid) was used as the indicator, because it is sensi- 

 tive to ammonia and to organic acids, and is not sensitive to carbon 

 dioxide except when the latter is present in fairly large quantity. The 

 end-point with corallin is not quite as sharp and distinct as with 

 phenolphthalein, and considerable practice is necessary before reliable 

 results can be obtained. 



APPARATUS. 



On account of the high resistance of the alcoholic solutions of the 

 acids, it was found necessary to make use entirely of the cylindrical type 

 of conductivity cell. The method of obtaining the constants of these 

 cells was described by White 3 and by Wightman. 4 



1 Amer. Chem. Journ., 44, 156 (1910); 46, 56 (1911); 48, 320, 411 (1912); 50, 1 (1913). 



2 Journ. Amer. Chem. Soc., 36, 2247-2249 (1914). 



3 Amer. Chem. Journ., 42, 527 (1909). 4 Ibid., 42, 527 (1909); 44, 64 (1911). 



