Alchemy symbols have not just been used for elements across the ages but also to represent compounds and experimental techniques in chemistry.
Alchemy is a term used to describe the historical study of elements and matter with the goal of creating an elixir for immortality or trying to change metals into more precious metals.
Alchemy whilst being the study of such wild theories as the transmutation of metals and prolonging of life also had many useful origins of chemistry today from drug design to experimental techniques we still use in the lab today.
Alchemy symbols are illustrations that have been used by alchemists for hundreds of years to communicate between alchemists about different elements and scientific methods in the pursuit of alchemy. It was also used as a way to protect their discoveries and findings as often they were only known by a few people.