Mixed melting point - Criteria of purity of organic compound

The melting point of two carefully mixed substances is known as mixed melting point. This can as well be used for determining the purity of a compound . The substance, whose purity is to be checked, is mixed with a pure sample of similar compound. The melting point of the mixture is ascertained. If the melting point of the mixture is sharp and comes out to be similar as that of pure compound, it is make sure that the compound under test is pure. Alternatively, if the melting point of the mixture is less than the melting point of the pure compound, the compound in query is not pure.