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ELECTROLYTIC SEPARATION OF METALS BY 

 GRADED ELECTROMOTR^E FORCES. 



Albert Carver. 



I give herewith some observations on a new method of 

 electrolytic separation of metals by graded electromotive forces. 

 This experimental physical work depends upon the fact that 

 the salts of the different metals have different decomposing 

 values. Freudenburg showed how it was possible to separate 

 metals quantitatively in this manner. 



It is only necessary to have two salts of the metals, which 

 have decomposing values as far apart as possible. When an 

 E. M. F. between these limits is passed through the cell, the 

 metal with the lower decomposing value will separate ; after 

 that is separated the- current will cease and it is only neces- 

 sary to raise the E. M. F. in order to deposit the other metal. 



When the concentration of the ions in the salt of the metal 

 separated becomes decreased, as it almost invariably does, it 

 is only necessary to raise the E. M. F. slightly. The amount 

 of increase is small and may be readily calculated from the 

 following formula : 



N Eo ^"&' p 



If p decreases from 0.1 normal to (i.odoiioI normal, P must 

 be increased 0.3 volts for a monovalent element and but half 

 that amount for a divalent element. For example AgNOs^ 

 0.70 and PbfNOg)^^! .52. 



When these two solutions are together the Ag will be en- 

 tirely decomposed by an E. M. F. of less than one volt; then 

 the E. M. F. may be raised to L52 or more, and all the 

 lead will be deposited. Separations are easily made in this 

 way. 



Below are given the separation values of a few ions. They 



