Check your inorganic chemistry books under electronegativity. Sodium's
about as good as it gets, iron and copper not in the same league. Of
course it helps to have a good acid electrolyte in your cell.

Now try cleaning your silver with baking soda in an aluminum pan....

"Dan White" wrote in message
et...
First of all let me say that my interest in this thread, started by Sandy,
was caused by my own questioning of why salt helped clean copper pots with
vinegar.