Potassium Campden Tablets - 2 oz. / Use to prevent oxidation. Contains potassium metabisulfite & is a convenient way to accurately sulphite wine. Each tablet contains 450 mg of active sulphite/tablet. These tablets are added crushed and are used as sterilizing agents. The usual rate is two tablets per gallon for sterilizing the must; the same at the first racking; and one tablet at successive rackings. The actions of metabisulphite are dealt with under Sulphite and Sterilizing.