What is "dithionic acid"

Hyposulphuric \Hy`po*sul*phur"ic\, a. [Pref. hypo- + sulphuric.] (Chem.) Pertaining to, or containing, sulphur in a lower state of oxidation than in the sulphuric compounds; as, hyposulphuric acid.

Hyposulphuric acid, an acid, H2S2O6, obtained by the action of manganese dioxide on sulphur dioxide, and known only in a watery solution and in its salts; -- called also dithionic acid. See Dithionic.

n. (context chemistry English) An unstable substance, H₂S₂O₆, known only in its solutions and in certain well-defined salts.

Dithionic acid, HSO, is a chemical compound known only in solution.