Section 68. Change of Conductance with Concentration. ij$ 



in table 67 under l B a. They have been corrected to round concentrations 

 by means of the cube-root function. The values at 156 are similarly 

 derived except that a correction was first applied by subtracting from the 

 concentration of the salt (Cba) that of the hydrolyzed portion still exist- 

 ing even in the presence of the largest quantity of added acid or base. The 

 A values are calculated from those for sodium acetate and chloride given 

 in table 36, section 54, and those for ammonium chloride here given. 



It is of some interest to compare the results at 18 with those obtained 

 previously by Kohlrausch.* As far as the data are comparable they are 

 placed side by side in the following table. 



Table 60. Conductivity results of different investigators. 



The agreement of the ammonium chloride values is within about 0.3 

 per cent. Kohlrausch's values for sodium hydroxide, however, are 4 to 5 

 per cent lower than ours, and his value for ammonium hydroxide at 100 

 milli-normal is 6 per cent higher. As Kohlrausch's data are derived from 

 his earlier measurements made in 1885, it is probable that the discrepancy 

 arises from impurities in the substances or water used by him, especially 

 since his values for potassium hydroxide (231 at 4 milli-normal, 219 at 50 

 milli-normal) after allowing for the difference in equivalent conductance 

 of the potassium and sodium ions (21 or 19 units) accord within 1 per 

 cent with ours for sodium hydroxide. 



68. CHANGE OF THE EQUIVALENT CONDUCTANCE WITH THE 

 CONCENTRATION AND TEMPERATURE. 



With reference to the change of the conductivity with the concentration, 

 we will limit ourselves to a consideration of the data for sodium hydrox- 

 ide ; for those with ammonium chloride and acetate do not cover a suffi- 

 cient range of concentration. 



*See Kohlrausch and Holborn's Leitvermogen der Elektrolyte, pp. 159-160. 



