<prompt> Composition of fixer solution:Na thiosulfate, acetic acid, Na2SO4, KBrNa thiosulfate, acetic acid, Na2SO4, AlHydroquinone, acetic acid, Na2SO4, KBrHydroquinone, acetic acid, Na2SO4, Al  <response>: Fixing solution also contains four components, all dissolved in water: 1 clearing agent, 2 acidifier, 3 preservative, and 4 hardener. Clearing AgentAn aqueous solution of ammonium thiosulfate hypo dissolves the unexposed silver halide grains. AcidifierThe fixing solution contains an acetic acid buffer system pH 4 to 4.5 to keep the fixer pH constant. PreservativeAmmonium sulfite is the preservative in the fixing solution, as it is in the developer. HardenerA hardening agent, usually aluminum sulfate, complexes with the gelatin during fixing and prevents damage to the gelatin during subsequent handling. Reference: White and Pharoahs Oral Radiology Principles and Interpretation 7th edition page no 70 