36 



ENERGY CHANGES INVOLVED IN DILUTION OF AMALGAMS. 



Hence it is unnecessary to calculate the values ir x and tt 2 at all ; it is enough 

 to find the logarithm of the concentration ratio of each amalgam in terms 

 of A z correct to o.oi, to observe the two ordinates corresponding to these 

 logarithms, and to subtract the smaller from the greater. The difference is 

 Dir 3 , the desired quantity. 



log 2 log4 logS l0gl6 log 32 log64 



Fig. 6. Preliminary Results with Zinc Amalgams. 



Deviations from the theoretical potential are plotted in millivolts as ordinates ; 

 logarithms of the concentration-ratios as abscissas. The most concentrated amalgam 

 at the origin contained about 0.9 per cent of zinc. The downward curve at the right 

 is due to oxidation. 



Since Dtt x -}- Dir z = Dir 2 we can predict Dir 2 if D-k 1 and Dtt 3 are known. 

 This method will be used again and again to get the total ordinate for amal- 

 gams which were not directly compared with A z . Of course some risk of 



