Sodium Metabisulfite is White or light yellow crystal powder, a strong smell of sulfur dioxide, relative density is 1.4, easy to dissolve in water(20?,54g/100ml water, 100?,81.7g/100ml water) and glycerin, water solution. It has acidity, and its solubility will become large while raising the temperature and is less to dissolve in ethanol,Damp easily decomposed, when exposed in air, easily oxidized into sodium sulfate. And acid contact and the generated sulfur dioxide released corresponding salts. Heated to 150 ? decomposition