It is used for distillation or dry distillation of substances.
It consists of a spherical vessel with a long downward-point neck. It is usually made of glass. However, we can also find find metal and sand ones.
The Arabian alchemist, Jabir ibn Hayyan (c. 721-c. 815) invented it.
With the pass of the years, the retort became obsolete and was replaced by more modern ways of distillation. However, the retort was used until the XIXc, for processes in which caustic gases which destroy corks or rubber caps are obtained.