Two compounds with different solubilities in a solvent S can be separated by fractional crysatllisation. When a hot saturated solution of these two compounds is alloed to cool, the less soluble compound crystallises out first while the more soluble remains in the solution. The crystals are separated from the mother liquor and the mother liquor is again concentrated and the hot solution is allowed to cool when the crystals of the second compound are obtained. These are again filtered and dried.
