Is a technique that makes a solid substances and impurities pure by dissolving the substance to be purified and then saturated at the boiling poing of the solvent then filt 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 fittet,while hot let the solution cooled dowe gradually filterd so that solid crystallization filfrate the extract crystals from aqueous solution crystallizel clear crystals and to make dry