34 



ENERGY CHANGES INVOLVED IN DILUTION OF AMALGAMS. 



Potentials of Zinc Amalgams. Second Series {Cell II). 



Temperature of thermostat (corrected) = 23.01 = 296.09 abs. 

 Temperature of i-volt cell 20 ; electromotive force = 0.9924. 



Sum of (a) and (d) and (f) = 0.049795 ; (c) =0.04980. 

 Sum of (a) and (f) =0.02123 ; (b) =0.02124. 



Sum of (d) and (f) =0.041515 ; (e) =0.04152. 



These agreements between sums of several potential differences, and the 

 observed values of the totals are eminently satisfactory. In the rest of the 

 final experiments, the checks obtained were uniformly as good as these ; 

 therefore, after this measurements made merely as a test of the accuracy of 

 others will in general not be included in the tables of results. 



The electromotive forces observed are constant throughout the day if the 

 temperature of the cell remains unchanged. After forty-eight hours, during 

 which time the supply of hydrogen had been discontinued and the thermostat 

 had cooled down, cell II, when warmed up to its previous temperature, read 

 as follows : 



All the potential differences had increased, by an amount bearing a direct 

 relationship to the dilution of the amalgam. The causes of the variation 

 were probably the diffusion of oxygen from the air into the cell, or changes 

 of concentration in various parts of the electrolyte due to evaporation and 

 condensation on the upper part of the cell. The differences are not very 

 great, however ; and it is safe to conclude that the earlier values are correct. 



Let us now attempt to generalize the results so far obtained : In all but 

 one case the calculated potential exceeds the observed ; the difference be- 

 tween the two, which from now on we will call Dtt, is the greatest when a 



