Electrical Conductance in Absolute Ethyl Alcohol. 10."> 



an indicator, and it showed results concordant with the phenolphtha- 

 lein values previously obtained. The methyl red naturally was use- 

 less in the titration of most of the organic acids, so its use was aban- 

 doned after proving the value of the phenolphthalein procedure. 



In order to dry completely our various pieces of apparatus, acetone 

 was used, as suggested by Barnebey. 1 The acetone was dehydrated 

 over calcium chloride and then redistilled. 



APPARATUS. 



The cylindrical type of conductivity cells was used in all save the more 

 concentrated solutions, where the ordinary plate type was adopted. 

 The reason for using the cylindrical cell lies in the fact that the organic 

 salts in absolute alcohol, although having greater conductance than 

 the organic acids, are nevertheless of sufficient resistance to warrant 

 such a procedure. White 2 and Wightman 3 have described the method 

 for obtaining the constants of these cells. 



Both the temperature coefficients of expansion of alcohol and the 

 temperature coefficients of conductance of substances in it as a solvent 

 are so large that it was especially necessary to maintain the solutions 

 at a constant temperature to within 0.01. The thermometers were of 

 the differential Beckmann type and were carefully compared with a 

 standard Reichsanstalt instrument which had in turn been calibrated 

 at the Bureau of Standards. The combined gas-regulator and thermo- 

 regulator was devised by Davis and Hughes. 4 The improved form of 

 constant-temperature bath, as devised by Davis, 5 was used in our 

 investigation. These baths are capable of even finer temperature 

 adjustment than that stated above as employed in our work. 



The resistance-box used throughout this work was calibrated at the 

 Bureau of Standards. The improved Kohlrausch slide-wire bridge 

 was employed, by means of which it was possible to read distances on 

 the slide wire corresponding to tenths of a millimeter (the total length 

 of the wire being 5 meters). Special precautions were taken to remove 

 all external resistance in the circuit. No. 10 B. & S. insulated copper 

 wire was used, and all leads coming to the bridge were dipped into a 

 mercury-contact rocking commutator. 



In the volumetric work Jena flasks were employed (50, 100, 200, 

 250, 500, 1,000 c.c.) which had been previously calibrated in this labora- 

 tory and recalibrated by ourselves, using weight methods. Reichsan- 

 stalt double-mark pipettes were recalibrated before use. In filling 

 and draining the pipette the following device was suggested by Dr. 

 Davis. It consisted of a right-angled T-tube with a glass stopcock on 

 the base of the T, the pipette being attached by rubber to one end of 



l Journ. Amer. Chem. Soc. 37, 1835 (1915). "Zeit. physik. Chem. 85, 519 (1913). 



2 Amer. Chem. Journ. 42, 527 (1909). 5 Carnegie Inst, Wash. Pub. No. 210, 21 (1914). 



3 Amcr. Chem. Journ. 44, 64 (1911). 



