Refinishing furniture: How to test for shellac?

I am preparing to refinish an older table. I'm not sure of the current finish (shellac vs. lacquer vs. varnish). I know that shellac would be soluble in denatured alcohol, however, I'd prefer not to buy a 5 gallon container of denatured alcohol just to test it. Will shellac also liquefy in 80 proof drinking alcohol (i.e. vodka)? That would allow me to test a small, inconspicuous area before buying a large container of denatured alcohol. Thanks.