332 ON THE CALCULATION OF THE CONDUCTIVITY OF 



the conductivities at regular intervals were read off and divided 

 by the value of p for that salt, Kohlrausch's values being 

 employed, viz., for sodium chloride 1030 and for barium chloride 

 1150, the conductivity unit being the same as hitherto. The 

 quotients thus obtained were taken to be the values of the ionic 

 concentrations. These last, divided by the corresponding dilu- 

 tions, were plotted against the dilutions, and from the curves 

 thus obtained, by Prof. MacGregor's graphical process, the 

 common value of the ionic concentration of the electrolytes in 

 their respective regions in the mixture and their dilutions 

 throughout these regions, were found. The products of the 

 latter values and the former gave the corresponding ionization 

 coefficients. The plotting was done on very various scales as 

 was necessary in order to plot all the curves so that readings 

 could be made to 0.1 per cent. The calculation of the conductiv- 

 ity required three readings from the curves representing ionic 

 concentration and dilution. Supposing these curves correct, the 

 error involved in making these readings might amount to 0.15 or 

 0.2 per cent. 



Results of Calculations. 



The following table gives the results of the calculation of the 

 conductivity of the mixtures. The first two columns give the 

 concentration in gramme-equivalents per litre of the NaCl and 

 Bad 2 solutions before mixing, their volumes being then equal. 

 The third, fourth, and fifth columns give the ionic concentrations 

 and the dilutions of each salt in its portion of the mixture, each 

 of these being expressed in terms of the units and quantities 

 before described. The sixth and seventh columns give the 

 specific conductivity at 18C, in terms of 10~ 8 times the specific 

 conductivity of mercury as calculated, and the value of the same 

 determined experimentally. The eighth column gives the excess 

 of the calculated over the measured value expressed in fractions 

 of 1 per cent of the latter. 



