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 Eimer 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 18°C a conductivity 
varying from 0.88 x 10~'° to 0.97 x 107*° expressed in terms of 
the conductivity of mercury at 0°C. 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 condueticity 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 
ems. It was provided with circular electrodes of stout platinum 
* Journ. Phys. Chem., Vol. I., p. 91. 
