Apparatus set up for distillation. In this case, the flask at left contains a mixture of compounds resulting from the fermentation of glucose, including the desired product, ethanol. The flask is heated, boiling off the components. The condensing tube is surrounded by cold water, which condenses the gas back into a liquid. The resulting liquid is then collected through the pipe at right. This is the process used to concentrate the ethanol, which has a lower boiling point than water, and thus more boils off at a given temperature. This process is used in the manufacture of distilled spirits.