128 



be inferred from Hulktt's') words: "many of these cells are still 

 in good order after five years." 



This would be in pei-fect accordance with onr own experiences: 

 CLARK-cells w^hich contain ZnSO^ . 6 H,0 as solid depolarise)* preser- 

 ved their E.M.F. for five years notwithstanding their having been 

 standing at room temperature, i. e. 25 degrees below the transition 

 point of Z11SO4. 6H,0. As in the case of Hullet's cells they had 

 been sealed up after formation. 



12. On account of these observations it might be expected that 

 even under circumstances favourable to a transformation (stabilisation) 

 of the negative electrode only a certain number of Hulett cells 

 would show the transformation. 



On December 11"' 1913 we prepared three H.C. (N". 1. 2 and 5) 

 in the way described abov e (§ 3) at i-oom temperature (30 mgr. Cd on 

 the spirals). We then substituted a 12.5 percent cadmiumamalgani 

 for the I percent. The E.M.F. was now 0.0503 Volt. After standing 

 for tw^o months at room temperature the cells were measured again 

 on February 26^'^ 1914. The E.M.F. ot" 1, 2 and 5 had decreased \o 

 0475 Volt at 25°.0 C. and this value remained unchanged. As 

 might have been expected the E.M.F. had decreased by stabilisation 

 of the cadmium. 



13. We prepared two new cells (nos. 6 and 7) in the same way 

 as 1, 2. and 5. Immediately after the preparation their E.M.F. were 

 0.04847 and 0.04795 Volt respectively. Some days later these values 

 became constant : 0.04788 and 0.04778 Volt. Stabilisation had begun 

 already during electrolysis. 



14. In order to determine whether <(-cadmium is formed during 

 electrolysis if, this modification is present on the spirals before electro- 

 lysis begins, we shunted the cells 6 and 7 in a current of 1 milli- 

 arapère. In this way we deposited upon the «-cadmium which was 

 present, a fresh quantity of 30 mgr. 



After formation we put a fresh (12.5 percent) amalgam into the 

 cell, while a fresh solution of cadmium sulphate was also introduced. 



Subsequent to this treatm'ent the E.M.F. at 25°.0 C. was again 

 0.0502(i Volt which proves that y-cadmium had been formed on the 

 old layer of ff-cadmium. 



15. On continuing our experiments we found that on one occasion 



i> Trans. Amer. Eleclrochem. Soc. 15, 435 (1909). 



