*disulphuric*

a. [ Pref. di- + sulphuric. ] (Chem.) Applied to an acid having in each molecule two atoms of sulphur in the higher state of oxidation. [ 1913 Webster ]

Disulphuric acid, a thick oily liquid, H2S2O7, called also Nordhausen acid (from Nordhausen in the Harts, where it was originally manufactured), fuming sulphuric acid, and especially pyrosulphuric acid. See under Pyrosulphuric. [ 1913 Webster ]