and the Weston Normal Cell. 261 



experimentally realized because of some difference in the 

 thermal treatment of the amalgams, for it has already been 

 shown that the electromotive properties of an amalgam vary 

 with such treatment. If so we conclude that cells with 

 amalgams containing more than 11 per cent, of cadmium 

 may hare E.M.F/s at 0° 0., differing very considerably from 

 the E.M.F/s of cells with from 3 to 11 percent, of cadmium. 

 The results also lead one to suggest that the transition 

 temperatures of the amalgams containing from 11*5 to 13*5 

 per cent, of cadmium are below 20° 0. but above 0° C. 

 Experiments to test this point were immediately proceeded 

 with, but before describing them the results obtained with 

 other groups of cells are of interest. 



The new groups of cells contain cadmium from Har- 

 rington, Kahlbaum, Merck, and from an electrolytic 

 source. Each of the new amalgams was made by adding 

 metallic cadmium to mercury, and all of them were melted 

 inside the glass vessels and allowed to cool in a normal 

 manner. The E.M.F/s of these cells were comparod at 

 many temperatures, hut it will be sufficient for the present 

 purpose to give the E.M.F/s atO 3 0. (p. 262). In order that 

 comparisons may be readily made the original E.M.F/s at 

 0°C. are also given for the first group of cells. 



The results obtained with the four new groups of cells 

 confirm the conclusions arrived at with the cells of Group L, 

 and furthermore suggest that the maximum values for the 

 E.M.F/s of the cells with amalgams containing high per- 

 centages of cadmium have not yet been obtained. If, as 

 suggested on p. 260, the result of slowly cooling an amalgam 

 to a temperature at which it should (if homogeneous) be in 

 a solid state is the production of an outer shell of amalgam of 

 comparatively low cadmium concentration, covering a solid 

 core of higher concentration, then different rates of cooling 

 should produce different results. Also, it seems probable 

 that by raising the temperature until the amalgam is com- 

 pletely liquid, and then chilling, the differences of concen- 

 tration will be largely avoided : but if the amalgam is not 

 in the completely liquid condition at the high temperature, 

 or nearly so, the effect of chilling may not be marked. 

 To test the first effect, a 11 per cent, amalgam was made 

 and divided into two parts ; these were placed in two limbs 

 of the same vessel. One of the parts was completely melted 

 and allowed to cool in a water bath down to a temperature 

 of about 16° ; the other part was completely melted and 

 chilled by quickly immersing the limb containing it in 



