Liebig's condenser
In the 1850s, this form of condenser was considered to be the most convenient. Invented by the chemist Justus von Liebig, it consists of an outer black lacquered brass tube, through the axis of which a glass tube is passed, and is supported by perforated corks: the space between the two tubes was filled with water, which was continually renewed by cold water which entered by a funnel near the lower extremity, while the hot water escaped at the other end.