400 PROCEEDINGS OF THE AMERICAN ACADEMY. 



increase between 0.1 and 0.001 normal in the case of the acids to the 

 corresponding increase in the case of neutral salts, the conductivity of 

 the water having been first subtracted in all cases. By subtracting from 

 these values the conductivity of the negative ions, which had been de- 

 rived from tlie conductivity and transference values of nei:tral diionic 

 salts, he arrived at the value 318 for the equivalent conductivity of the 

 hydrogen ion at 18° C. — a value, however, which he regards only as a 

 rough estimate. Three years later* he deduced also the temperature 

 change of this conductivity, expressing it by the equation: 



At = 318 [1 + 0.0154 (t - 18) - 0.000033 (t - 18)^]. 



Quite recently Noyes and Sammet t have deduced the equivalent con- 

 ductivity of the hydrogen ion by an independent method; namely, by 

 combination of the transference number of moderately dilute hydro- 

 chloric acid with the equivalent conductivity of the chlorine ion derived 

 from transference determinations and conductivity measurements of po- 

 tassium chloride. The value thus obtained is 330 at 18° or 3.8 per cent 

 greater than tliat of Kohlrausch. The authors consider that this diver- 

 gence cannot be due to experimental errors, but that it must arise either 

 from an error in the extrapolated values of the conductivity of acids at 

 extreme dilution, or from some real defect in the theoretical considera- 

 tions from wliich the identity of the results of the two methods is 

 predicted. 



As it seemed possible to eliminate to a great extent the effect of the 

 impurities in the water by appropriate measurements of the conductivity 

 of dilute acids and a treatment of the data by certain methods to be de- 

 scribed below, we undertook an investigation in this direction, both 

 with nitric and with hydrochloric acid, and desire now to present the 

 results which have been obtained. It may be stated in advance that tliese 

 results are in substantial agreement with the extrapolated value of 

 Kohlrausch. 



II. rUEPARATION OF THE SOLUTIONS. 



In the preparation of the solutions, water was used which liad a spe- 

 cific conductance of 0.8 — 1.5 X lO"'' reciprocal ohms and wliich had 

 been purified by redistillation of ordinary distilled Avatcr to which alka- 

 line permanganate was added, the first and last portions of tlie distillate 



* Sitzungsbericlite der Preuss. Ak.ad. d. Wissenschaften, 1901, 1026. 

 t Journ. Amer. Cliem. Soc, 24, 9G5 (1902); 25, 165 (1903). Zeitschr. pliys. 

 Chem., 43, 49 (1903). 



