I2(> 



From the drawing it can be seen that the E.M.F. of these cells 

 at 25°. is independent oi* the concentration of the amalgam when 

 its concentration lies between 9.0 and 24.4 at.percents (i. e. 5.9 and 

 15.4 percent by weight). As soon as the concentration decreases below 

 5.97a ^y weight (when we pass from the heterogeneons amalgams 

 to the homogeneous, fc.f. Bui/s paper Fig. 3) the E.M.F. varies with 

 the amonnt of cadmium present in the amalgam, the potential against 

 pure cadmium iiicreasltui with Jc^c^^^a.yf in the percentage of cadmium. 



7. In the light of these facts the high E.M.F. of freshlj' constructed 

 cells becomes intelligible. 



During electrolysis the cadmium which is deposited on the spiral 

 is withdrawn from the upper layer of the 12.57„ (or stronger) amal- 

 gam, which was originally a two phase system. It is thus possible 

 for this layer to become a monophase system and if this is the case 

 the E.M.F. will increase wlien electrolysis is continued. After the 

 formation of the cell its E.M.F. will then be too high. In the long 

 run ea(hniiim will diffuse to the upper layer: this becomes again a 

 twt)phase system and the E.M.F. will decrease and finally becomes 

 constant. 



8. In order to check this supposition we carried out the following 

 ex})eiiment : We put two platijium spirals into the //-shaped tube i>* 

 (Fig. 1). into the right-side tube we put some r/o (l^J weight) cad- 

 mium amalgam (99 parts by weight of mercury, 1 part of cadmium). 

 This amalgam is a fluid monophase system at ordinary temperature. 

 We filled the tubes with a dilute solution of cadmium sulphate (half 

 saturated at 15° C). After this the cell was formed in the way 

 described above. (1 milliampère). 



After having deposited 20 or 25 milligrams of cadmium on the 

 left-hand siViral, the capillary tube on the right was brought into 

 connection with a waterpumj) in order to remove the amalgam. A 

 number of small pieces of the 12.57, amalgam were then substituted 

 for this. 



These cells give at once an E.M.F. of 0.0503 Volt when they are 

 |)ut into a thermostat at 25°0 0. It is evident that our assumption 

 made above (§ 7) is correct. 



9. AH the cells we investigated have been produced in the way 

 described ; it is now possible to measure their E.M.F. at once with- 

 out waiting for 8 to 14 days before 'their becoming constant. 



10. Our dilalometric measurements with cadmium which had been 



