AQUEOUS SOLUTIONS. ARCHIBALD. 319 



are given in Table I. Similar data for Sodium Sulphate are 

 given in my previous paper.* As the above data, in the case of 

 the Potassium Sulphate, are better than those given in my 

 previous paper, I have thought it well to make new observations 

 and calculations on these mixtures. Concentrations, dilutions, 

 concentrations of ions, and conductivities, are expressed in terms 

 of the same units as in Table II. 



The results of this table show that the calculated and 

 observed values of the conductivity of mixtures of equi- 

 molecular solutions of Potassium and Sodium Sulphates agree 

 within the limits of observational error, at least up to a concen- 

 tration of 1 gramme-equivalent per litre. The observations of 

 my former paper, in which the mixtures examined were not 

 equi-molecular in concentration, gave a similar result. 



Conclusions. 



An examination of Tables II, V, and VI, will show, that in 

 the case of the Potassium-Copper sulphate solutions, the differ- 

 ences between the observed and calculated values of the 

 conductivity, are all of the same sign and positive from a con- 

 centration of O.I to one of 1.294 equivalent gramme-molecules 

 per litre, that the differences increase with the concentration, 

 reaching in the case of the strongest solution examined 

 6.38 per cent. 



For the mixtures of Sodium and Potassium Sulphates and 

 of Zinc and Copper Sulphates examined, the difference for a like 

 concentration are not greater than 0.30 per cent. Now, errors 

 are caused in the calculations by taking the ionization coeffi- 

 cients to be the ratios of the specific molecular conductivity at 

 infinite dilution, which is rigorously true only for infinitely 

 dilute solutions, and also by taking the value of the specific 

 molecular conductivity at infinite dilution for an electrolyte in a 

 mixture to be the same as the value found by observations on 

 the simple solutions, which is strictly true only for infinitely 



* Loc. cit. 



