102 Conductivity of Aqueous Solutions. Part IV. 



41. EQUIVALENT-CONDUCTANCE VALUES AT ROUND CONCENTRATIONS. 



The conductance values in table 21 which refer to different concentra- 

 tions at different temperatures have been reduced to a uniform round con- 

 centration by graphic interpolation with the help of the linear function 



- = \- K(CA) m discussed in section 17. The so-reduced values are 



A A 



presented in table 22, except those for sodium and potassium chlorides, 

 which have already been summarized in table 9, section 16. As these are 

 our final values it may be again stated in explanation of the table, that, as in 

 the preceding tables, the concentration is expressed in milli-equivalents per 

 liter based on the international atomic weights for 1905 referred to oxygen 

 as 16.00 ; that the temperature is the true temperature on the hydrogen-gas 

 scale as derived (at the higher temperatures) from the determinations of 

 Jaquerod and Wassmer of the boiling-points of naphthalene and benzo- 

 phenone ; and that the equivalent conductance, which has been corrected 

 for that of the water, is expressed in reciprocal ohms, the absolute conduct- 

 ance-capacity of the conductivity vessel having been derived from Kohl- 

 rausch and Maltby's data for sodium and potassium chloride at 18 and 

 corrected for its change with the temperature. The concentration given 

 in the second column is that at the temperature of the measurement. 



The conductances at zero concentration were obtained in the cases of 

 silver nitrate, barium nitrate, and potassium sulphate, at 100 and above, 



by graphic extrapolation upon plots of the function = \- K(CA) m 



A A 



At the higher temperatures the results are doubtless much in error owing 

 to the large extrapolation involved, but they are the best obtainable from 

 the data. At 18 we have inserted for zero concentration the values cal- 

 culated from Kohlrausch's conductance values for the separate ions of the 

 potassium sulphate, barium nitrate, and magnesium sulphate. In the case 

 of magnesium sulphate at the higher temperatures, the method employed 

 for the other salts was inapplicable owing to the large hydrolysis, and 

 there are at present no independent data upon which a fully satisfactory 

 determination of its A value can be based. But, in order to give some 

 idea of the relation of its conductivity at the various concentrations to 

 that of the completely ionized salt, we have assumed that, at 100 and 

 above, magnesium and barium ions have the same equivalent conductance 

 and have computed rough A values by the relation A 0( M g so 4 ) : =A 0( BaN2O6)+ 

 A (K 2 so 4 ) A 0( kci). The assumption that chloride-ion and nitrate-ion 

 have the same equivalent conductance is also involved ; but this assump- 

 tion is doubtless substantially correct. The so-computed A values for 

 magnesium sulphate are given within parentheses in the table. 



