# The melting point of a white solid substance was determined in four repeated trials to be 56.0°C, 55.0°C, 57.5°C, 55.5°C. What temperature should be reported as the melting point as a result of these trials?

You often see in the literature the phrase, $\text{recrystallized to constant melting point}$; i.e. a material is successively recrystallized until a consistent melting point is achieved. Often, after repeat recrystallizations, (and each recrystallization step is a purification step!), the measured melting point goes up because the impurities that depress melting point are successively eliminated.