258 Mr. F. E. Smith on Cadmium Amalgams 



With regard to the 6 per cent, amalgam, at 30° C. the 

 following values were observed : — 



Date. E.M.F. - 1 -01840 v. + 



22.2.1902. -0-00059 v. 



23.2. „ -0-00127 



24.2. „ -0-00140 



24.2. „ -0-00140 



This change is shown hereafter (p. 271) to be due to the 

 closeness of the 6 per cent, amalgam at 30° C. to the transi- 

 tion temperature (about 28° C), at which the two phase 

 system changes into a one phase (liquid) system. The tran- 

 sition appears to take place slowh , and the E.M.F. of the 

 cell does not therefore immediately assume a constant value. 

 It is purely accidental that such a change was only observed 

 with the 6 per cent, amalgam. 



Many of the cells containing amalgams with from 14 to 

 20 per cent, of cadmium did not remain constant when the 

 temperature was unchanged. The variations will be seen 

 from Table II., which gives the initial and final values at 

 the different temperatures. 



Of the cells dealt with in Table II. the E.M.F.'s of all the 

 cells, with the exception of that containing the 15 per cent, 

 amalgam, increased in value when maintained at 0°. During 

 the 3 months that the cells were at 15° C. the 15, 17, and 

 19 per cent, amalgam cells fell in E.M.F., and the 14, 14£, 

 and 16 per cent, amalgam cells rose in value. At the higher 

 temperatures there was very little change, but it is worthy of 

 notice that the 18 and 19 per cent, amalgam cells exhibited 

 declining values. 



After the cells had remained at 45° C. for 2 days they 

 were again placed in crushed ice and kept there for 6 weeks. 

 The E.M.F. 's were measured from time to time, and were 

 far from constant for the amalgams of higher concentration. 

 The following table (III.) gives the results, and for the sake 

 of comparison the original values at 0° C. are also given. 



The cells containing the amalgams with from 2 to 11*5 

 per cent, of cadmium may be regarded as quite constant. 

 Amalgam cells with from 12 t<< 13*5 per cent, of cadmium 

 have tallen in E.M.F. by a few hundred-thousandth* of a 

 volt, while those with amalgams richer still in cadmium (with 

 the exception of the 20 per cent, one) show considerable 

 changes which in two instances (14*5 and 16) amount to 

 0-U04 volt. With increasing time the E.M.F.'s of these cells 

 are observed also to increase, but even after 6 weeks the final 



