126 



Conductivity of Aqueous Solutions. Part V. 



the hydrochloric acid, since their effect is ordinarily to decrease by an in- 

 definite amount the conductance of a solution of a strong acid rather than 

 to increase it. In the case of acetic acid (and of sodium acetate with ace- 

 tic acid added) the effect of the impurities would depend on their nature: 

 bases (e. g., ammonium hydroxide) and salts (c. g., ammonium carbonate, 

 sodium silicate) would increase the conductance of the solution by an 

 amount equal to or greater than their own conductance, but very weak 

 acids (for example, carbonic or silicic) owing to the reduction of their 

 ionization would scarcely influence it at all. Since the water used was 

 distilled from an alkaline solution (of permanganate) and was scarcely 

 exposed to the atmosphere, it seems most probable that the impurities 

 present are basic or saline ; and therefore that it is best to subtract the 

 conductance of the water. It has seemed advisable, however, to apply 

 this correction to the final rather than to the separate values, and to give 

 for comparison both the corrected and uncorrected results. 



Table 32. Actual conductance of the water. 



52. CONDUCTIVITY DATA FOR SODIUM CHLORIDE, HYDROCHLORIC 

 ACID, ACETIC ACID, AND SODIUM ACETATE. 



The following table contains the direct results of the observations and 

 the equivalent conductances computed from them. The first column gives 

 the date of the experiment ; the second, the cell-number of the conductivity 

 vessel; the third, the concentration at 4 in milli-equivalents per liter (the 

 number of milli-equivalents being based upon the atomic weights referred 

 to oxygen as 16.000 and the weights being reduced to vacuo) ; the 

 fourth, the temperature on the hydrogen-gas scale at which the conduct- 

 ance was measured ; the fifth, the concentration at the temperature of 

 the measurement, calculated by dividing the concentration at 4 by the 

 ratio of the specific volume of the solution at that temperature to its speci- 

 fic volume at 4*, and applying the correction at 156 for the vapor space ; 



*The specific-volume ratio at 100 and 156 was assumed to be identical with that 

 for pure water. At 100 this value is 1.0432 according to Matthiessen and Rosetti; 

 at 156 it is 1.0976, interpolated graphically from Hirn's values [Ann. chim. phys. 

 (4), 10, 32 (1867)] at 140.17, 151.00, and 160.68 after correcting them to the pres- 

 sures of saturated aqueous vapor with the help of the compression-coefficient of 

 water, derived by extrapolation from the data of Pagliani and Vincentini which 

 extend only to 100 [Landolt-Bornstein-Meyerhoffer, Tabellen 60 (1905)]. 



