A process for extracting sodium by the electrolysis
of molten sodium chloride. The Downs cell has a
central graphite anode surrounded by a cylindrical
steel cathode. Chlorine released is led away through
a hood, over the anode.
Molten sodium is formed at
the cathode and collected through another hood around
the top of the cathode cylinder. The two hoods and
electrodes are separated by a coaxial cylindrical
A small amount of calcium chloride is
added to the sodium chloride to lower its melting
point. The sodium chloride is melted electrically
and kept molten by the current through the cell. More
sodium chloride is added as the electrolysis proceeds.