A few years back I had a sack of pennies that had become quite
corroded. Knowing how Baking Soda had done such a good job
on my Battery cables. I decided to give it a try. The Soda ate into
the dates and ruined almost all of the pennies. Yours being Brass
may be another Story. Whatever you do. Do it with caution. You
dont want to ruin your goodies.