Reflux heating using an electric mantle. Use of an electric mantle allows higher temperatures than the water bath heating method. The heat boils the liquid, allowing the reaction to proceed at the boiling point of the solvent. The tubes are bringing water to the condenser, cooling the solvent gas so that it condenses back into the reaction vessel, rather than escaping out of the top of the reflux apparatus. This allows long periods of heating without excessive loss of solvent. For the apparatus for reflux with a water bath, see T875/1273.