Formula:       Na₂SO₃
 Mol.Weight:    126.04
 Properties:
    White to slight yellowish crystalling powder. Soluble in water but insoluble in
alcohol and most organic solvents. slowly absorbs oxygen from the air forms sulfate.
 Main uses:
    Pulp and paper industry. especially for CHEMITHERMO-MECHANTCAL PULPING; water
reatment; photography; food preservative; textile bleaching; oil recovery and 
ore flotating.
 Specification  （GB　9005-88）
 
    TECH　TERM            EXTRAGRADE          1ST.GRADE      2.ND.GRADE
　　 Na₂SO₃ %＞                    97                    96                93
  IRON(as Fe) %＜                 0.003                 0.005              0.01  
  Water Insolubles %＜             0.02                 0.03               0.05 
  Free Alkali (as Na₂CO₃)%＜       0.10                 0.40               0.60 
  Sulfate(as Na₂CO₄) %＜           2.5                   －                  － 
  Chloride(as NaCl) %＜           0.10                   －                  －