Section 112. Preparation of the Solutions. 



3*5 



normal, which were standardized for use in this work against these barium 

 hydroxide solutions showed as a mean in each case of 5 or 6 determina- 

 tions a content in milli-equivalents per kilogram of solution as follows : 



The very dilute solutions (approximately 0.002 normal) of nitric and 

 hydrochloric acids employed could hardly be titrated with sufficient accu- 

 racy by this method. The concentrations both of the original solutions and 

 of the portions after electrolysis were therefore determined by measuring 

 their conductance by the usual Kohlrausch method in a cylindrical cell 

 with horizontal electrodes, and dividing the corresponding specific con- 

 ductance by the equivalent conductance of the acid in question at this 

 concentration and temperature. Goodwin and Haskell* have recently 

 determined the equivalent conductances at 18 in 0.002 normal solution 

 to be 371.3 for HNO s , and 375.0 for HC1 at 18, from which follows with 

 the help of Deguisne's temperature-coefficients :f 383.4 for HN0 3 and 

 387.4 for HC1 at 20, which are the values we have used in calculating 

 the original concentrations. The actual conductance measured in the 

 conductivity vessel, the specific conductance, and the concentration in 

 milli-equivalents per liter calculated therefrom were as follows : 



*The value found before the first experiment with this solution was 21355, that between the 

 fourth and fifth experiments was 21372, showing that there was no considerable change from 

 contamination during the course of the work. 



The conductance-capacity of the conductivity vessel was 0.3956 for all 

 the measurements presented in this article.^ Hydrochloric acid solution 

 No. 1 was made by diluting quantitatively by weight (with water of con- 

 ductivity 0.9 X 10" 6 ) a 0.13737 normal solution which had been stand- 

 ardized by weighing the silver chloride obtainable from it; the concen- 

 tration calculated from the dilution was 2.015 in close agreement with 

 that derived from the conductivity (2.017). Solution No. 2 was pre- 

 pared from the same stock solution, which was itself made by treating 

 pure salt with pure sulphuric acid, redistilling the strong acid obtained, 

 and diluting it ; it was proved to be free from non-volatile matter and 

 from sulphuric acid. 



*Phys. Rev., 19, 381, 383 (1904). These values like all of ours given below were 

 not corrected for the conductance of the water. 



fKohlrausch and Holborn, Leitvermogen der Elektrolyte (1898), p. 199. 



$A 0.009954 normal potassium chloride solution measured in it showed as an aver- 

 age of several determinations a conductance of 3111.3 X 10~ 6 reciprocal ohms. 



