(i) impure solid is dissolved in minimum amount of solvent, insoluble impurities are filtered out .solution containing soluble impurities is heated till crystallization point. The crystals of pure substance separate out leaving behind impurities in mother liquor.
(ii) It is based on the principle of selective adsorption of the components of a mixture between two phases, stationary phase and a moving phase. When stationary phase is solid the basis is adsorption and when it is liquid the basis is partition.
