EXTRAPOLATION TO INFINITE DILUTION. 



65 



The atomic volumes of zinc and cadmium were taken as respectively 9.5 

 and 13.0 in making these calculations. 



Thus in both cases the system suffers contraction when the amalgamation 

 takes place. The striking point is that zinc amalgams continue to contract 

 when diluted, showing apparently that molecular rearrangement is still in 

 progress. The contraction of cadmium, however, does not increase so 

 greatly, a sign that the monatomic condition prevails more nearly in concen- 

 trated amalgams of this metal. 



None of these results is accurate enough to form the basis of exact quan- 

 titative calculation, but all point in the same direction. When more accu- 

 rate measurements of the osmotic pressure have been made, further produc- 

 tive speculation concerning the extent of this strongly indicated partial 

 association of zinc in concentrated amalgams will be possible. 



THE APPLICATION OF THE GAS LAW AT INFINITE DILUTION. 



It is interesting to note that whatever may be the cause of the superposed 

 effects, the sum total of irregularities in the case of zinc and cadmium dimin- 

 ishes in each case at about the same rate as dilution proceeds. The follow- 

 ing table gives the values of the difference between the observed potentials 

 and those demanded by the gas law, when various amalgams of zinc and cad- 

 mium are compared with the extrapolated value for infinite dilution. These 

 values are taken from the curves given on pages 45 and 49. 



Evidently the doubling of the concentration in each case produces a nearly 

 double amount of the irregularity ; hence the curves are very similar in shape. 

 The results are advantageously depicted together in figure 10. 



