MIXTURES OF ELECTROLYTES—MACGREGOR. 113 
will have a double effect on the calculated conductivity, (1) 
affecting the value of © as determined from the curves, and (2) 
introducing the factor p in the final computation. In the case 
of Bender's solutions, though in some cases they were nearly or 
quite saturated, the first effeet was so small as to be much less 
than the error incidental to the graphical process, and I did not 
therefore take it into account. The second effect was also very 
small; but as in some cases it was nearly as great as Bender's 
estimated error, I took it into account in all the calculations. 
While Kohlrausch’s solutions had at 18°C both the constitu- 
tion and the conductivity specitied in his tables, Bender’s solutions 
had at 15° the constitution, and at 18° the conductivity ascribed 
to them. I found that it did not appreciably affect the values 
found for % and % to regard the concentrations at 15° as being 
the concentrations at 18°, but that this approximation was 
inadmissible in calculating the conductivity, as in some cases it 
made a difference of about the same magnitude as Bender's 
estimated error. Hence in the calculations, I took as the values 
of m, and %., Bender’s values multiplied by the ratio of the 
volume of the solution at 15° to its volume at 18°. As Bender 
measured the thermal expansion of his solutions, his paper 
furnishes the necessary data for this correction. 
The conductivities given by Bender as the results of his 
observations are the actual results of measurement, and are thus 
affected by accidental errors, which in some cases are considerable. 
In order that his observations might be rendered comparable 
with the results of calculation, these accidental errors must as 
far as possible be removed. I therefore plotted all his series of 
observations on co-ordinate paper, drew smooth curves through 
them, and estimated as well as I could, in this way. the 
accidental errors of the single measurements. The corrections 
thus determined are given in the table below in the column 
headed : Correction a. 
Bender himself draws attention to certain differences between 
his observations of the conductivity of simple solutions of K Cl 
and Na Cl, and those for solutions of the same strength con- 
