CONTRIBUTIONS FROM THE CHEMICAL LABORATORY OF 

 llAKVAKD COLLEGE. 



THE CONTACT-POTENTIAL BET^yEEN METALS AND 

 FUSED SALTS, AND THE DISSOCIATION OF FUSED 

 SALTS. 



By Clarence McCheyne GoRDOjir. 



Received October 10, 1808. 

 Presented by Theodore W. Richards, October 12, 1898. 



The potential difference between fused salts and metals immersed in 

 them is a quantity of great importance because of its relation to the theory 

 of the origin of contact-potentials, on account of the light it throws upon 

 the decree of dissociation of salts in their fused state, and in view of its 

 bearing upon the electrolytic separation of the metals. Notwith^taud- 

 insj; these important relations, the subject has received practically no 

 attention at the hands of scientific investigators. In a few cases cells 

 containing fused salts as the electrolyte have been measured, but always 

 with some other end in view than the study of the single potential differ- 

 ence between metal and salt.* 



The practical difficulties in the way of carrying out an exhaustive in- 

 vestigation of this subject are many. Among the more important of 

 these are the fact that many salts decompose below or slightly above 

 their melting point, the disturbing effect of side reactions which at ordi- 

 nary temperatures would be so slow as to cause little or no inconvenience, 

 and the impossibility of using glass vessels at temperatures as high as the 

 melting points of most inorganic salts. Such difficulties as these have 

 prevented me from extending the investigation rapidly, but the results 



* Lash Miller (Zeit. fiir pliys. Chemie, X. 459, 1892) used fused salts in experi- 

 ments to prove that there was no change in the contact-potential as the metal 

 chantred from liquid to solid state. 



Poincare (Ann. cliim.et phys., [6.], XXI. 289, 1890) measured reversible cells con- 

 taining melted zinc and tin salts with the heat of reaction as the end in view. He 

 investigated also some polarization phenomena with silver electrodes. 



