Vinegar
From Tardis Wiki, the free Doctor Who reference
Vinegar is a human-made preservative, used for pickling and flavouring foods. Mickey Smith, for instance, kept eggs pickled with vinegar in his pantry. Vinegar contains acetic acid, which could kill Raxacoricofallapatorians, because of their calcium-based biology. (DW: World War Three, SJA: Revenge of the Slitheen)
