Abstract
The potential of the concentration cell 
plotted as a function of the mole fraction 
gives a sigmoid curve but there is no sharp end point as the contents of the test half‐cell change from acidic (Cl−‐poor) to basic (Cl−‐rich). The potential of the cell 
shows Nernstian behavior for the Cu(II), Cu(I) couple over a limited Cu(II) concentration range. Current‐overpotential relations at a copper electrode immersed in the 
fused salts obey the Butler‐Volmer equation. Exchange current densities and symmetry coefficients have been calculated for melts of composition 
. Transference numbers have been measured for the melts; both 
cations and chlorocuprate(I) anions such as 
are significant charge carriers. Electrochemical cells based on combinations of a copper electrode in the chlorocuprate(I) melts with an aluminum electrode in low melting chloroaluminate fused salts have been made and tested.