possible coin cleaning

dennis here aka pokie i have a question for anybody that would know i have a 1908 s i think barber quarter it is a key date from what i have gathered is there a safe way to clean it a little you can hardly see the mint mark it has a heavy black film over it thanks dennis

put a peice of foil in a bowl, put the quarter on top of the foil, add baking soda, then add boiling water.....sorted

Angel's method for cleaning silver coins, explained step-by-step:

http://www.americandetectorist.com/forum/index.php?topic=813.0

thanks guys for the advice i did the foil and baking soda in hot water it cleaned it up about as good as it is going to get found out it was a 1908 d not a 1908s like i thought but it is still a good find thank you dennis