RICHARDS AND LEWIS. 



ZINC AND CADMIUM AMALGAMS. 



97 



h = —.04895. Therefore Q = —2255. That is, a gram atom of zinc 

 (65.4 grams) takes up 2255 gram calories iu dissolving iu 6500 grams 

 of mercury, or to greater dilution. 



This method of determining thermal quantities is evidently one of 

 great accuracy and convenience in cases where it is applicable. The 

 data concerning the heats of amalgamation of zinc and cadmium which 

 have previously been obtained are meagre. With these, however, the 

 present results are in agreement. Thus Obach* found a cooling effect 

 when zinc was amalgamated, a warming when cadmium was amalgamated. 

 P'uvre t found for the heat of solution of amalgamated zinc 39.43 Kg- 

 cal., for that of pure zinc 37.34 Kg-cal. The difference between the 

 two represents the heat of amalgamation of zinc or — 2100g-cal. The 

 agreement of our result — 2255 with this is striking. 



The difference iu potential between the solid metal and its saturated 

 amalgam should be emphasized. It is often stated that the potential of 



TABLE V. Zinc veksds Amalgam. 



* Jahn, Grundriss der Elektrocheniie, p. 8. 



J These values were taken as the basis of the formula. 



VOL XXXIV. — 7 



t Ibid. 



