There are several types of condensers, but their main mission is to condense the purified vapors escaping the fractionating column. All condensers work the same, in simple and fractional distillation. A glass tube is surrounded above and below by a water jacket. The bottom half of the jacket is connected to a cold tap, allowing cold water to flow through and cool the bottom half of the condenser tube. The cold water must come in from the bottom, which is the coldest end, to avoid thermal shock to the glassware. The top of the jacket is where this water flows out to make space for new, cold water to enter the bottom. The boiling point of the vapors entering the condenser is measured at the top of the condenser, where the distilling head and condenser meet. The mouth is where the condensed liquids exit, due to gravity, into the receiving flask.

Figure 1: Illustration of a condenser where some parts are highlighted.