308 ON THE CALCULATION OF THE CONDUCTIVITY OF 



The work included the purification of the salts and of water, 

 preparation and analysis of a series of simple solutions of the 

 constituents of the double salt and determination of their con- 

 ductivity ; plotting curves, giving the relation of concentration 

 of ions to dilution for these simple solutions ; preparation of the 

 double salt and of its solutions, and measuring and calculating 

 their conductivity. The experiments were conducted in the 

 Physical and Chemical Laboratories of Dalhousie College. 



Purification of Materials. 



The salts were obtained as chemically pure, from Eirner and 

 Amend of New York. They were carefully re-crystallized three- 

 times. No iron or other impurities could be detected in the 

 Copper Sulphate. 



The water used was purified by the method described by 

 Hulett,* except that a block tin condenser was used instead of a 

 platinum one. It was found to have at 18C a conductivity 

 varying from 0.88 xlO" 10 to 0.97 xl(r 10 expressed in terms of 

 the conductivity of mercury at 0C. It was kept in bottles 

 which had been used for this purpose for several years. In the 

 case of the more dilute solutions, where the water would 

 appreciably effect the conductivity of the solution, the conduc- 

 tivity of the water used in making up a solution was substracted 

 from the observed conducticity of that solution. 



Experimental Methods. 



Details as to the preparation and analysis of simple solutions 

 and the measurement of the conductivity, will be found in the 

 paper referred to above. I mention here only points in which 

 the procedure of the present paper differs from the procedure of 

 the former. 



The only change in the apparatus was the use of a cylindrical 

 electrolytic cell in measuring the more dilute solutions. This, 

 cell was about 14 cms. long, and had an internal diameter of 3.3. 

 cms. It was provided with circular electrodes of stout platinum, 



* Journ. Phys. Chera., Vol. J., p. 91. 



