Corrosive Sublimate is a poisonous white powder created by heating salt together with Turpeth Mineral, (which is Basic Mercuric Sulfate (Hg₃O₂SO₄) aka Yellow Precipitate) in a retort, then sublimated to separate it from the byproducts (aka Caput Mortuum). It was used as an antisyphilitic and disinfectant in early medicine.