64 PROPERTIES OF ELECTRICALLY CONDUCTING SYSTEMS 



approach the mass-action law as a limiting form may we be reasonably 

 certain that the extrapolated value of A is correct. In other cases, 

 therefore, the limiting conductance values are more or less arbitrary. In 

 a subsequent chapter this question will be discussed somewhat more at 

 length. For the present we shall assume that the A values obtained by 

 the ordinary methods of extrapolation are approximately correct. 



The values of the equivalent conductances of the different electrolytes 

 in ammonia and water have been given in Tables III, XXII and XXIII. 

 In comparing the conductances in the two solvents, however, it is pre- 

 ferable to compare the conductance of the individual ions, rather than 

 that of the sum of the ions of any given electrolyte. Before proceeding 

 further, therefore, we shall resolve these values of the conductance for 

 the various electrolytes into two parts, namely the conductance of the 

 positive and of the negative ion respectively. In order that this may be 

 done, it is necessary that the transference number of at least one elec- 

 trolyte shall be known. In the case of ammonia solutions the transfer- 

 ence numbers of a considerable number of electrolytes have been deter- 

 mined by Franklin and Cady. 19 With the aid of their data, the follow- 

 ing values of the equivalent conductance of the typical inorganic ions 

 have been calculated. 20 For the sake of comparison, the ion conduct- 

 ances of the same ions in water at 18 are given as well as the ratio of 

 the ion conductances in ammonia and in water. 



TABLE XXVI. 

 ION CONDUCTANCES IN AMMONIA AND IN WATER. 



Ion In NH 3 In H 2 A NH /A R Q 



Positive Li + 112 33.3 3.36 



Ag + 116 54.0 2.15 



Na + 130 43.4 3.00 



NH 4 + 131 64.7 2.03 



T1+ 152 65.9 2.31 



K + 168 64.5 2.61 



Negative Br0 3 - 148 47.6 3.11 



N0 3 - 171 61.8 2.77 



I- 171 66.6 2.57 



Br- 172 67.7 2.54 



Cl- 179 65.5 2.73 



NH 2 - 133 



"Franklin and Cady, J. Am. Chem. Soc. 26, 499 (1904). 

 10 Kraus and Bray, loc. cit. 



