Sodium Metabisulphite (NaO2CCH2)2NCH2CH2N(CH2CO2H)2
Used as a preservative in developers
Used in place of sodium sulfite in some developers, particularly in two-solution formulas where the increased acidity of the metabisulfite inhibits oxidation. For acidifying fixing baths.
Used as a clearing agent in platinum palladium printing and in New Chrysotypes