Prohibition Cognac, sealed and dated

I have a sealed bottle of Caecilia Cognac, dated 1937.  It has tax stamps and labeled for medicinal purposes only.  It was found in the wall of a building in Chicago, during renovations.  My father had the entire case and the wooden box they came in.  I am tryng to find out how to preserve it and keep it from further evaporation.  The top of te cork is damp and I

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