To sanitise home brewing equipment. E223 Sodium metabisulphite is a white, non-stable powder, which reacts with oxygen to form sodium sulphate. In acidic conditions it forms sulphurous acid, which acts as a preservative. It is used as a preservative in some products and may be used as a bleaching agent.
Sodium Metabisulphite 100g
Do not breathe in this powder.