Pyrosulphuric

Pyr′o‐sul‐phu″ric (?), a. [Pyro- + -sulphuric.] (Chem.) Pertaining to, or designating, an acid called also disulphuricacid) obtained by distillation of certain sulphates, as a colorless, thick, oily liquid, H2S2O7 resembling sulphuric acid. It is used in the solution of indigo, in the manufacture of alizarin, and in dehydration.