Liebig condenser (short)

A condenser is a piece of laboratory glassware used to cool hot vapors or liquids. A condenser usually consists of a large glass tube containing a smaller glass tube running its entire length, within which the hot fluids pass. The ends of the inner glass tube are usually fitted with ground glass joints which are easily fitted with other glassware. During reflux, the upper end is usually left open to the atmosphere or vented through a bubbler or a drying tube to prevent the ingress of water or oxygen. The outer glass tube usually has two hose connections, and a coolant (usually tap water or chilled water/anti-freeze mixture) is passed through it. For maximum efficiency, and to maintain a smooth and correctly directed thermal gradient so as to minimise the risk of thermal shock to adjacent glassware, the coolant usually (though not necessarily; see 'Allihn condenser - refluxing' below) enters through the lower fitting, and exits through the higher fitting. Maintaining a correct thermal gradient (i.e. entering coolant at the cooler point) is the critical factor. Multiple condensers may be connected in series. Normally a high flow rate is not necessary to maintain a cooling surface. [Condenser (laboratory). Wikipedia]