hydrothionic

Century Dictionary and Cyclopedia

1. Noting an acid discovered by Sehützenberger and first called by him hydrosulphurous acid, now generally called hyposulphurous acid, this latter name having formerly been used for a different substance now known as thiosulphuric, acid, H₂S₂0₃. The formula for Schützenberger's acid is probably H₂S₂O₄. It is an energetic reducing agent.