free sulphuric acid(A method of leaching zinc from a zinc concentrate by grinding the zinc concentrate in an aqueous solution containing free sulfuric acid and ferric ions. Dominator_Salvator)
oil of vitriol(Sulfuric acid (American spelling and the preferred IUPAC name) or sulphuric acid (Commonwealth spelling), known in antiquity as oil of vitriol, is a mineral acid composed of the elements sulfur, oxygen and hydrogen, with the molecular formula H2SO4. It is a colorless, odorless and viscous liquid that is miscible with water. wikipedia.org)
