Crystallization. It is the process of separating a pure substance in the form of crystals having well defined, geometrical shape from its hot saturated solution by cooling. This process is very commonly used to purify solid substances.
To prepare crystals of alum
Take some distilled water in a beaker. Go on adding alum powder in installments slowly simultaneously with continuous stirring of the solution with a glass rod. Heat the beaker gently and try to dissolve more alum powder till it stops dissolving more alum powder. Filter the hot saturated solution in a glass beaker and allow it to cool. Observe the solution. Well-defined crystals of alum will be obtained after some time.
