... 820-9purity:99%stability:Stable, but air sensitive. Incompatible with strong acids, strong oxidizing agents, water, moisture.melting point ... "food additives Sodium metabisulfite" printed on the external packing, with the sign of "Avoid moisture and heaStorage & defence: ... the production date. It should be transported by clean car, with covering matter, avoid rain SSA23 sodium sulfate,anhydrous Na2SO4 ...