monothionic

monothionic, a. Chem.

(mɒnəʊθaɪˈɒnɪk)

[See mono- 2 and dithionic.]

In monothionic acid, a very unstable fluid, H₂SO₂, obtained by the action of diluted sulphuric acid on iron or zinc, with exclusion of air.

in Syd. Soc. Lex.