162 Conductivities and Viscosities in Pure and in Mixed Solvents. 



EXPERIMENTAL APPARATUS. 



The Kohlrausch method of measuring conductivity was employed 

 with Wheatstone bridge, telephone receiver, and induction coil. A full 

 description of the apparatus and the method of its use may be found in 

 the earlier publications of work from this laboratory. 



Because of the concentrated solutions employed, a different type of 

 cell was necessary. This consisted of a hard-glass, U-shaped tube, 

 fitted with ground-glass stoppers. The glass tubes carrying the elec- 

 trodes were sealed by means of sealing-wax into the holes bored in the 

 centers of the stoppers. The distance between the electrodes could 

 thus be adjusted if occasion demanded. Numbers were etched upon 

 the stoppers and the corresponding arms of the U -tubes, so that the 

 electrodes could always be placed in the same position. 



The temperature was very satisfactorily maintained by means of a 

 new thermostat described in detail by Jones, Davis, and Putnam. 1 



All flasks and burettes were carefully calibrated. Solvent and solu- 

 tions in all cases were brought to within 0.1 of the necessary tempera- 

 ture before measurements were made. 



SOLVENTS. 



WATER. 



The water was purified by the method of Jones and MacKay 2 

 as modified by Schmidt, and had a mean specific conductivity of 

 1.5Xl(T 6 at25 C. 



ISOCHLORIC SOLUTIONS. 



Two solutions are said to be isochloric if they contain in unit volume 

 the same number of chlorine ions. In this work we have used a solu- 

 tion of potassium chloride normal at 25, and the solution of calcium 

 chloride with which this would be isochloric. 



Arrhenius 3 shows, for the condition of isohydric solutions 



ma_np 



Applying this to the solutions under discussion : 



a = percentage dissociation of normal solution of potassium chloride ; 



(3 = that of the corresponding solution of calcium chloride. 

 Let ^i = liters of solution containing a gram-molecular weight of potas- 

 sium chloride and v- 2 = corresponding symbol for the calcium chloride. 

 Let m = number of chlorine ions per molecule of potassium chloride and 

 n = same for calcium chloride. 



Carnegie Inst. Wash. Pub. No. 210, 119 (1915). 3 Zeit. phys. Chem. 2, 284 (1886). 



2 Amer. Chem. Journ., 17, 83 (1895). 



