Cas no: 7772-98-7 mf:na2s2o3.5h2o purity:99% Use: 1. Used in photographic processing as a photographic fixer 2. Electroplate applications in steel, as part of patina recipes for copper alloys 3. Used in the tanning of leather 4. In ph testing of bleaching substances 5. In waste water treatment, neutralizing bleached and chlorinated water. 6. To lower chlorine levels in swimming pools and spas following super chlorination 7. Used in bleach 8. Used in paper industry 9. Used to remove iodine stains, e.G. After the explosion of nitrogen tri-iodide. 10. Used in aquaculture