204 



PROCEEDINGS OF THE AMERICAN ACADEMY. 



TABLE VI. — Continued. 



second and third. All of the conductivity values are expressed in recip- 

 rocal ohms. 



The agreement of the conductivity determinations made at different 

 times, and often with different solutions, will be seen from this table. A 

 comparison of the initial and final values in the separate experiments 

 shows also the degree of contamination during the heating. 



Table VIII contains a summary of the results given in Table VII. 

 In deriving the means from the latter table, both the " initial " and 

 "final" values have been included for the 0.1 and 0.01 normal solutions; 

 but for the diluter solutions only the "initial" values have been con- 

 sidered: for, owing to contamination, the others are not equally reliable. 

 The 18° values are those of Kohlrausch and Maltby.* The values given 

 in parentheses for zero concentration were obtained by extrapolation as 

 described in Section XIII. 



In order to compare the conductivity values at different temperatures, 

 it is desirable to correct those directly measured for the change in con- 

 centration produced by the expansion when a given solution is heated. 

 The values in Table VIII, which, owing to this expansion, refer at 

 different temperatures to somewhat different concentrations, as is there 

 indicated, have been reduced to the nearest round concentrations by a 

 graphic interpolation with the help of the linear function iV = Aq — A'C'i 

 (see Section XIII). The so-reduced values are presented in Table IX. 



* Wissensch. Abhandl. phys.-tedin. Keichsaiistalt, 3, 210 (1900). 



