A Civilization advance.
The basis for modern chemistry was laid by practitioners of the pseudo-science alchemy. The primary goal of alchemy was to find a way to turn base metals into gold and silver, usually through the agency of elixers of a Philosopher's Stone. Alchemy periodically surfaced and degenerated until the science of chemistry proved itself with medically and economically useful applications.
Prerequisites: Medicine and University.
Allows for: Explosives and Refining.