Thanks for everyones input -

Ed and Charles - As luck would have it I have a large collection of 1c
and 2c coins, but I think I will go with the copper sulphate option (or
splash it around with some sulphur dioxide). This seems to be a little
more "scientific" (if not, let me know)


Lum - Your book looks like the goods, thanks for that, I have some after
dinner reading I think...



Now for the fun,as was noted, we have little to loose.

Charlie