The Downs cell uses a carbon anode and an iron cathode, the electrolyte is magnesium chloride but solid magnesium chloride is a poor conductor of electricity.
The Downs cell uses a carbon anode and an iron cathode. The electrolyte is magnesium chloride that has been heated to the liquid state. Although solid magnesium chloride is a poor conductor of electricity, when molten the magnesium and chloride ions are mobilized, which become charge carriers and allow conduction of electric current. 
