OF AQUEOUS SOLUTIONS. BARNES. 123 



As both Reyher and Wagner regard their results as affected 

 by a possible error of about 3 in the third decimal place, it is 

 seen that the agreement between the calculated and observed 

 values for all the salts except copper sulphate is very satis- 

 factory, the differences being well within the limit of experi- 

 mental error. In the case of copper sulphate, the agreement 

 is not so satisfactory. But it was noticed on plotting the 

 observed values against the concentration that the points do not 

 lie on a smooth curve, and that the point corresponding to the 

 concentration 0.5 is at quite a distance from this curve, which 

 leads one to think that this observed value cannot be correct. 

 The poor agreement in this case might also be partly due to the 

 doubtful value of the specific molecular conductivity at infinite 

 dilution used. Thus it seems that for all the salts examined, 

 copper sulphate perhaps excepted, expression (1) gives the vis- 

 cosity of a solution within the limit of experimental error 

 throughout a concentration range of 1.0 to 0.125. 



Mixtures of Solutions. 



As there is no change of volume on mixing the constituent 

 solutions of the above electrolytes of the concentrations given 

 below 1 , and as the solutions mixed were of equal volume and 

 also equimolecular, the expression (2) for the value of a property 

 in the case of a mixture of two electrolytes with a common ion, 

 reduces to : 



p = P + -^[&i (I - i) + *i i + fc, (1 - ,) + I* ",] (3) 



where n is the concentration of the solutions and the k's and I's 

 have the values obtained above for simple solutions of the 

 respective electrolytes. For the application of this equation to 

 the calculation of the viscosity of a mixture, all the quantities 

 required are known except the a's, the ionizatiou coefficients in 

 the mixture. 



1 See Trans. X. S. Inst. Sci., 9, 125, 1895-% ; also 9, 297 and 310, 1897 



