[GARDINER] CONDUCTIVITY OF MIXTURES OF DILUTE SOLUTIONS 39 



The silver nitrate and potassium chloride solutions were made 

 by dissolving known weights of each in distilled water, and after- 

 wards making the solutions up to the desired concentration. 



Experiment II. — To Determine the Cell Constant. 



The constant K which, for a given cell, depends on the size and 



shape of the electrodes, and on their distance apart, is equal to the 



specific conductivitv . , , . . 1 



ratio ■. 1 — -T-V— or since the conductivity = — -. 



measured conductivity resistance 



we have K = specific conductivity X measured resistance. In order 



N 

 to find the value of K a r^- solution of KCl whose specific con- 



50 



ductivity at 25°C is known to be 2.768 x 10~3^ was taken and its re- 

 sistance found at that temperature by the method described above. 

 The mean of several readings obtained in this way gave a resistance of 

 29.265 ohms, so that K = 2.768 x 10-3 x 29.265 = .08100552, with 

 this constant the specific conductivity of any other solution was 



K 



therefore given directly by — ^- ■;—-. r-;-^ — 



resistance of the solution 



Experiment III. — To 75 c.c. of redistilled water there was added 



(1 \T 



-^ c.c. j a ———— solution of HCl and the specific 



conductivities found for the different concentrations are given in the 

 following; tables I, II and III : 



TABLE I. 



