What is pertaining to, or designating, an acid obtained by the reduction of sulphurous acid. See Hyposulphurous acid, under Hyposulphurous called?

hydrosulphurous — Pertaining to, or designating, an acid obtained by the reduction of sulphurous acid. See Hyposulphurous acid, under Hyposulphurous. (Webster's 1913.)

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