H. S. Das , Kolkata, (Manufacturers of Alum, Aluminium Sulphate, Ammonia, Ammonium Chloride, Bleaching Powder, Calcium Carbonate, Caustic Soda, Copper Sulphate, Hydrochloric Acid, Potassium Chromate, Potassium Dichromate, Silver Nitrate, Soda Ash, Sodium Chloride, Sodium Chromate, Sodium Hydroxide, Sodium Hypochlorite, Sulphuric Acid, Trisodium Phosphate, Urea, Zinc Chloride and Zinc Oxide etc.)