206 



Conductivity of Aqueous Solutions. Part VII. 



Table 71 gives the conductance of the water as actually measured in the 

 bomb and its specific conductance at the temperatures 18, 218, and 306. 



Table 71. Conductance of water. 



*This experiment was given a weight of one-half, because of the abnormally 

 high final conductance at 18. 



The data and results of the calculation of the conductance due to hydro- 

 gen-ion and hydroxide-ion are as follows : 



Temperature 218 306 



Ah + Aoh 1565 1654 



Specific conductance X 10 of conductivity water 5.85 8.7 



X 10 6 of H and OH ions 3.35 2.1 



" " X 10 6 of impurities 2.5 6.6 



The observed conductance of the solutions was in every case corrected 

 by subtracting the conductance of the impurities. The fraction which this 

 conductance forms of the conductance of the 10 milli-normal ammonium 

 chloride or sodium acetate solutions is about 0.1 per cent at 18, 0.03 

 per cent at 218, and 0.05 per cent at 306 ; and of that of the 100 milli- 

 normal ammonium hydroxide or acetic acid is about 0.2 per cent at 18, 

 0.6 per cent at 218, and 4.0 per cent at 306. 



The correction for the conductance of ionized water at 218 and 306 

 still remains to be considered. In the solution of pure ammonium hydrox- 

 ide and acetic acid this correction is negligible, even in the most dilute solu- 

 tions, since the ionization of the base or acid is still sufficient to drive that 

 of the water back to an inappreciable quantity. In the solutions of pure 

 ammonium acetate, where very nearly equal quantities of acid and base 

 are produced by the hydrolysis, the conductance of the hydrogen and 

 hydroxide ions as given in the preceding table was directly subtracted. In 



