Is a technique that makes a solid substances and impurities pure by dissolving the substance to be purified and then saturated at the boiling point of the solvent then filtrate the aqueous solution while hot to get rid of impurities insoluble if the solution is get rid of the fill color sdditives powder decolorizing charcoal and filtrate,while hot let the solution cooled gradually filterd so that solid crystallization the extract crystals from aqueous solution crystallizel clear crystals and to make dry