Liebig condenser (long)

The Liebig condenser is the most basic water-cooled design. The inner-tube is straight, making it cheaper to manufacture. Though named after the German chemist Justus Baron von Liebig, he cannot be given credit for having invented it because it had already been in use for some time before him. However, it is believed that he popularized the device. ... The Liebig condenser is much more efficient than a simple retort due to its use of liquid for cooling. Water can absorb much more heat than the same volume of air, and its constant circulation through the water jacket keeps the condenser's temperature constant. Therefore, a Liebig condenser can condense a much greater flow of incoming vapour than an air condenser or retort. Additionally, stainless steel 'wool' or another heat-conductive, nonreactive material can be loosely placed in the inner cylinder of a Liebig condenser, substantially increasing the reflux effect, and the overall efficiency of the distillation. The cooling water should flow from top to bottom, as that also increases the efficiency and helps prevent thermal shock to the glassware. [Condenser (laboratory). Wikipedia]