300 ON THE CALCULATION OF THE CONDUCTIVITY OF 



The concentrations of solutions are expressed in terms of 

 equivalent gramme-molecules per litre at 180. The conduc- 

 tivities are specific conductivities at 18C expressed in terms 

 of I0~ 8 times the specific conductivity of mercury at 0C. 

 The concentration of ion (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 differences are within or but little 

 beyond the limit of the error of an observation, which would 

 be about 0.25 per cent. The sign also changes 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 (a) 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- 

 cular conductivity at infinite dilution for an elecrolyte in a 



* Loc. cit., p. 108. 



