Temperature at which the melting pointTemperature at which a solid changes to a liquid. A completely pure crystalline substance has an exact temperature at which it melts. Impure substances and amorphous substances will begin melting at one temperature and finish at another. For these substances the term "melting range" is more appropriate. Under some conditions Click on Term to Read More of a mixture of chemical constituents is as low as possible. All the constituents crystallize simultaneously below at this temperature from molten liquid solution. A schematic example of melting and phase relationships of a binary mixture AB is shown below with the eutectic point labeled “E”.