Alchemy is a strange protoscience precursor to chemistry often practiced in ancient periods. German King Otto I studied alchemy in an attempt to create weapons or extend life. Nazis were also interested in alchemy.
The substance Otto I discovered in the Parchments of Constinople, and used to create strange beasts of war was said to have been created through alchemical research, and perhaps by the Devil himself, and forces of Hell.
Behind the scenes
It is heavily implied that there is a tie between Alchemy and the research done by the Da'at Yichud.