DISCUSSION OF EVIDENCE. 



153 



the number of molecules of water with which a salt crystallizes and 

 its temperature coefficients of conductivity? 



This relation has already been discussed in Publication No. 170 of 

 the Carnegie Institution of Washington, in which the results of our 

 work on conductivity and dissociation has been published. Tables 48 

 and 49, showing temperature coefficients in conductivity units between 

 the temperatures 25 and 35, on the one hand, and between 50 and 

 65 on the other, at the dilutions g- and t ^ 4 normal, are taken from the 

 monograph referred to above. 



TABLE 49. Temperature coefficients of conductivity. 



We have seen that the hydrates formed by a large number of salts, 

 including those given in tables 48 and 49, have already been worked 

 out, 1 and that water of crystallization is a rough measure of water of 

 hydration. The salts in table 48 crystallize with little or no water, 

 and in aqueous solution are very little hydrated; those in table 49, in 

 general, crystallize with large amounts of water and are strongly 

 hydrated compounds. 



Let us compare the temperature coefficients of conductivity in con- 

 ductivity units (which are the actual increases in molecular conduc- 

 tivity per degree rise in temperature) of the substances in table 48 

 with those in table 49. It will be seen that the coefficients for the sub- 

 stances in table 48 are, at all dilutions and temperatures, much smaller 



Carnegie Inst. W T ash. Pub. No. 60. 



