OF ZINC, CADMIUM, LEAD, COPPER, AND LITHIUM 



6 7 



then, a gram-atom of lead dissolved in a hundred gram-atoms of mercury 

 must absorb about 540 joules or 130 calories on infinite dilution; and of 

 this amount about two-thirds is absorbed when the amalgam is diluted 

 with twice its bulk of mercury. 



With these figures are repeated also, in conveniently accessible form, 

 the other results obtained in this monograph by the application of the 

 equation of Helmholtz. 



TABLE 21. Heat of Dilution of Amalgams Calculated from the Electrical 



Measurements. 



Because the heat capacity of the reacting system is essentially constant, 

 these values are independent of the temperature, as far as our measure- 

 ments were concerned. Their chief uncertainty depends upon the diffi- 

 culty of measuring exactly the temperature coefficients of small electro- 

 motive forces : but they are accurate enough to serve as a fairly close 

 guide to the behavior of the respective amalgams. They are hardly close 

 enough to serve as the basis for a search after an exact mathematical law 

 governing the change of thermal effect with increasing dilution, although 

 such a search would be an interesting aspect of yet more precise measure- 

 ments. 



'Cv 





