208 



Dr. S. W. J. Smith on the Weston Cell 



is the percentage of B which the solid first deposited con- 

 tains. At any given temperature (0), liquid and solid alloys 











Fig. 1. 









100' 



75° 

 t 



50° 

 & 



25* 



4 



0* 



-25° 



4 



\ 











/' 



s* 



y 









■/ 



/* 













C&yT 





*/ 











/; 



/ ! 



/ 



X 







/x. 



... 



/ 









_c / 





/ 













/ 



/ 











/ / 



i 



rl ' 



2 



or. ' 



30°/ R 



can exist in equilibrium only when their percentage composi- 

 tions have definite values (represented by x and y respectively). 

 The thermodynamical method of accounting for this condition 

 of equilibrium is referred to later (§§ 12 and 14). 



Roozeboom was the first to suggest that the thermal 

 variation of the constitution of cadmium amalgams may be 

 determined by curves like those of fig. 1, so long as the 

 percentage of cadmium does not pass a certain limit (not 

 exceeded in the experiments discussed below), and this 

 suggestion was found to accord with various experimental 

 <lata obtained by Bijl. 



§ 3. Recent experiments on cadmium amalgams, — Mr. F. E. 

 Smith has thrown fresh light upon the problem and provided 

 new material for investigation by examining the effect of 

 "chilling," i. e. of cooling the amalgams suddenly from 

 temperatures at which they are wholly fluid to a temperature 

 below the freezing point of mercury. 



The most striking result of his experiments is shown in 



