There's always the option of using a solvent (with proper precautions of course). Perhaps test a few different solvents on the least desirable coins. Or, just enjoy the table as it is. Do you see anything particularly interesting in the collection?
If the coins have only low individual value, try a soak in kerosene or methylated spirits first, because those solvents are easier to obtain, more often more ready at hand, cheaper to buy and vapors less toxic, then try acetone. For coins of higher individual value, use acetone only.