IIJ.—On THE CALCULATION OF THE CONDUCTIVITY OF AQUEOUS 
SOLUTIONS CONTAINING THE DOUBLE SULPHATE OF 
COPPER AND POTASSIUM, AND OF MIXTURES OF EQUI- 
MOLECULAR SOLUTIONS OF ZINC AND COPPER SUL- 
PHATES. — By E. H. ArcnuipaLp, B.Sc., Dalhousie 
College, Halifax, N. S. 
(Communicated by Prof. J. G. MacGregor, 21st February, 1898.) 
In a paper,* read before this ‘Society last October, I showed 
that for mixtures of solutions of Potassium and Sodium Sulphate, 
when not more concentrated than one equivalent gramme- 
molecule per litre, it was possible, by the aid of the dissociation 
theory of electrolysis, and by employing Prof. MacGregor’s 
graphical method+ for the determination of the ionization 
coefficients in the mixture, to calculate the conductivity within 
or but little beyond the limits of an error of obsesvation. The 
conductivity of mixtures of solutions of Potassium and Sodium 
Chloride, which were measured by Bender, have been calculated 
by Prof. MacGregor,t who found that for mixtures of these 
solutions, more dilute than two equivalent gramme-molecules 
per litre, it was possible to caclulate their conductivity. within 
the limits of experimental error. D. McIntosh } has measured 
and caleulated the conductivity of mixtures of solutions of 
Potassium and Hydrogen Chloride, and found the conductivity 
calculable within the limits of experimental error, up to a mean 
concentration of one equivalent gramme-molecule per litre. 
At Prof. MacGregor’s suggestion I have made the observa- 
tions described in this paper, to find if the conductivity is also 
calculable in the case of a solution containing a double salt, on 
the assumption that the salt does not exist as a double salt in 
the solution. The salt selected was the double Sulphate of 
Copper and Potassium. 
* Transactions N.S. Inst. Science, IX. (1897), p. 291. 
+t Transactions N.S. Iust. Science, IX. (1896), p. 101. 
t Transactions N.S. Inst. Science. IX. (1896), p. 122. 
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