286 PROPERTIES OF ELECTRICALLY CONDUCTING SYSTEMS 



salts, nevertheless, the parallelism existing between the two sets of values 

 is unmistakable. 



The constants A are the equivalent percentage density changes due 

 to the ions. This property should be an additive one. If this is true, 

 the difference in the values of the constant A for salts with a common 

 ion should be constant. Heydweiller has calculated the value of the 

 constants A for different ions. To illustrate how nearly the additive 

 condition is fulfilled by the experimental values of the constants, the fol- 

 lowing values are given. Table CXIV-A relates to a series of sodium 

 salts and Table CXIV-B to a series of nitrates. In the first column is 

 given the symbol of the negative ion of the salt, in the second column the 

 experimentally determined value of the constant A, in the third column 

 the value of the constant A a for the anion, and in the last column the 



difference A A a = 



for the cation. 

 similar values are given for those salts. 



In the case of the nitrates 



TABLE CXIV, 

 SHOWING THE ADDITIVE NATURE OF A. 



1.40 

 1.40 

 1.38 

 1.41 

 1.36 

 1.40 

 1.25 

 1.48 

 1.32 

 1.34 



Mean 1.38 



4.52 

 4.55 

 4.57 

 4.59 

 4.59 

 4.62 

 4.43 

 4.49 

 4.48 

 4.51 

 4.51 

 4.55 

 4.60 

 (4.22) 

 4.53 



Mean 4.54 



It will be noted that the values of the constants A and Aj show remark- 



CL K, 



ably small variations. They thus fulfill the condition of additivity. 

 Only a few electrolytes, such as magnesium sulphate, sodium car- 



