Benzene from Coal-Tar Light Oil: Washed and Rectified, Lunge 1887

The light oil from coal tar (everything below about 170 °C) is rectified, washed with the strongest sulfuric acid and then weak caustic soda, and rectified again by steam in a column: the part up to 110 °C is 90-per-cent benzol. Washed and rectified once more, then frozen and pressed, it gives pure benzene (Lunge, 1887). Benzene is toxic and carcinogenic, and its vapour catches fire easily. The picture: our diagram of the route.