FORM OF THE CONDUCTANCE FUNCTION 91 



neighborhood of 0.4. This constant, therefore, is a characteristic prop- 

 erty of the electrolyte upon which the solvent has only a secondary influ- 

 ence. In this connection, it is to be borne in mind that various com- 

 plexes may be formed between an electrolyte and its solvent, upon the 

 nature of which complexes the constant D may depend. We should 

 therefore expect a certain amount of variation in the value of the con- 

 stant D for a given electrolyte in different solvents. Probably the change 

 in the value of D would be found to be much smaller in case the dielectric 

 constant were altered, not by a change of the solvent medium, but by a 

 change of the temperature. The constant ra is seen to decrease as the 

 dielectric constant increases. Since this constant is a property of the 

 electrolyte, as well as of the solvent, it follows that an exact comparison 

 cannot be made. However, it is clear that, for solvents of very low 

 dielectric constant, the value of ra approaches 2, whereas for solvents 

 of very high dielectric constant the value of ra is less than unity. In 

 the case of water ra appears to have a value in the neighborhood of 0.5. 

 The change in the value of ra as a function of the dielectric constant is 

 well illustrated in the case of silver nitrate dissolved in the amines. For 

 amylamine, ethylamine, aniline, methylamine, and ammonia the dielec- 

 tric constants are respectively 4.5, 6.2, 7.5, 10 and 22, and the values of 

 ra are 1.67, 1.45, 1.42, 1.22 and 0.83. It is seen that throughout this 

 series of solvents, which are similar in their constitution, the value of the 

 constant ra for silver nitrate decreases with increasing values of the 

 dielectric constant. 



The mass-action constant K decreases very rapidly as the dielectric 

 constant decreases. While there are numerous transpositions in the order 

 of the constants, which is to be expected, since this constant is a func- 

 tion of the constitution of the salt as well as that of the solvent, never- 

 theless, in a general way, there can be no question but that the mass- 

 action constant K decreases as the dielectric constant decreases. The 

 variation is much more regular when solutions in solvents of the same 

 type are compared. So, in the case of solutions of silver nitrate in 

 ammonia and its derivatives, the constants are as follows: ethylamine, 

 2.44 X lO' 8 ; methylamine, 0.8 X 10' 4 ; ammonia, 28 X 10' 4 . When the 

 dielectric constant falls below a value of approximately 10, the mass- 

 action constant for the typical salts has reached a value in the neighbor- 

 hood of 1 X 10-* and thereafter it falls off very rapidly with decreasing 

 values of the dielectric constant. No accurate data being available in 

 dilute solutions of solvents having a dielectric constant less than 10, it is 

 impossible to proceed further with the comparison. Assuming, however, 

 that the conductance function holds, it is possible to calculate the values 



