300 ON THE CALCULATION OF THE CONDUCTIVITY OF 
The concentrations of solutions are expressed in terms of 
equivalent gramme-molecules per litre at 18°C. The conduc- 
tivities are specific conductivities at 18°C expressed in terms 
of i0°° times the specific conductivity of mercury at 0°C. 
The concentration of ions (column 3) common to the two elec- 
trolytes in the mixture and the dilutions of the electrolytes in 
the mixture (columns 4 and 5) are obtained by Prof. MacGregor’s 
graphical process.* The former is the number of dissociated 
gramme-equivalents of either electrolyte present in the mix- 
ture, divided by the volume in litres of the portion of the solu- 
tion occupied by it. In any one mixture it has the same value 
for both electrolytes. The latter are the volumes in litres of 
the portions of the solution occupied by the respective electro- 
lytes divided by the numbers of gramme-equivalents present. 
In each mixture they have different values for the two electro- 
lytes. The product of the former into the value of the latter 
in the case of either electrolyte gives the ionization coefficient 
for that electrolyte in the mixture. 
It will be seen from the above table that the differences 
range from 1.47 per cent to 0.12 percent. that the greater differ- 
ences are for the stronger solutions, and that in the case of these 
solutions all the differences but one have the same sign. 
For more dilute mixtures than 0.7 equivalent gramme- 
molecules per litre, the ditferences are within or bnt little 
beyond the limit of the error of an observation, which would 
be about 0.25 per cent. The sign alsochanges frequently. The 
differences in these cases are therefore probably due to acci- 
dental errors. 
In the case of the stronger solutions, it was to be expected 
that the differences would be beyond the limit of error, as the 
ionization coefficients (2) were taken to be the ratios of the 
specific molecular conductivity to the specific molecnlar conduc- 
tivity at infinite dilution, and this is rigorously true only for 
infinitely dilute solutions. Also the value of the specific mole- 
eular conductivity at infinite dilution for an elecrolyte in a 
eTOCs Gib. ps. LOS: 
