Fractional distillation

Fractional distillation is used to separate two or more liquids that are miscible with one another

You put your mixture in a flask and stick a fractionating column on top. Then you heat it.
The different liquids will all have different boiling points so they will evaporate at different temperatures
The liquid with the lowest boiling point evaporates first. When the temperature on the thermometer matches the boiling point of this liquid it will reach the top of the column
When the first liquid has been collected you raise the temperature until the next one reaches the top