264 Mr. F. E. Smith or Cadmium Amalgams 



3 mm. in diameter and 30 cm. long ; the tube was then 

 filled with a 16 percent, amalgam. After the amalgam had 

 been completely melted and slowly cooled in a water bath, 

 the lower end o£ the tube was broken away so as to expose 

 part of the amalgam's surface. The amalgam rod was now 

 used as the negative element of two cells, the platinum wire 

 serving as the negative lead. In one of the cells the upper 

 part of the surface of the amalgam made contact with 

 cadmium sulphate crystals and solution, and in the other 

 cell the lower part of the amalgam's surface was in contact 

 with a similar mixture. After three hours at 15° C. the 

 cell containing the lower part of the amalgam was the higher 

 in E.M.F. by about 0*0001 volt, but the difference was not 

 constant, and both cells were increasing in value. We 

 conclude, therefore, that the large differences observed between 

 the chilled and slowly cooled amalgams are not due to such 

 local differences of concentration as have been indicated. * 



Cells with Chilled Amalgams. 



Another series of cells were now prepared with amalgams, 

 some of which were melted and afterwards slowly cooled 

 in a water bath, and others were melted and chilled by 

 immersion in alcohol cooled by means of solid C0 2 to about 

 — 50° C. After being chilled the amalgams were not allowed 

 to rise in temperature above 0° C, the cell being prepared 

 with the glass vessel immersed in a mixture of ice and salt. 

 After sealing and swilling with ice-cold water the cells were 



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placed in ice. 



With amalgams containing from 1 to 11 per cent, of 

 cadmium no difference greater than two hundred-thousandths 

 of a volt was observed between the electromotive effects of 

 chilled and slowly cooled amalgams of the same percentage 

 composition. 



With amalgams of higher concentration the chilled 



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amalgam cell had the higher E.M.F., and its value increased 



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for from 7 to 14 days, after which a slight fall was generally 

 observed. In Table VI. the E.M.F/s of the various cells 

 are given after the cells had been kept at a constant tem- 

 perature of 0° C. for 1, 5, 10 and 30 days. 



The E.M.F/s of the cells with the slowly cooled and 

 chilled amalgams — 1 to 11 per cent, of cadmium — were 

 practically identical with those given in Table I. (at 0° C), 

 and so they are not repeated here. However, in order that 

 comparisons may be made with a two-phase system amalgam 

 the E.M.F. 's of the 10 per cent, amalgam cells are given in 

 the Table. 



