On Sun, 27 Feb 2011 02:08:03 -0600, dilbert firestorm
wrote:

there's a website that showed you how to remove zinc from a copper
plated penny.

end result, all the zinc was gone and you got a very thin piece of
copper penny left over.

don't remember which acid they used.

It might have been an episode of Modern Marvels: Acid.

IIRC they demonstrated this and mentioned just how thin the cooper was
over the zinc.