Fractional distillation is the process used to separate a mixture of miscible liquids whose boiling points differ by less than 25°C. The experimental setup is similar to that of distillation except for a fractionating column which is filled with glass beads.

In this method, the mixture is heated using a burner, and both the liquids most likely enter the vapour state. The vapours hit the glass beads in the column and tend to condense. Out of the two vapours, the vapour component which is less volatile cools faster than the other and returns to liquid state. Gradually, the more volatile component reaches the top of the column and is passed through the condenser as shown in the figure and gets liquefied.

The less volatile component remains in the round bottom flask.

The process is repeatedly done to completely separate the two liquids.