This character is an alchemist.
Alchemy refers to a quest for a fabled elixir or kimia (Old Persian for "elixir", later arabicized as alchemy) capable of turning copper and other base metals to gold and also a quest for something to prevent human beings' bodies from becoming old.
Alchemy is both a philosophy and an ancient practice that seeks to prepare the "elixir of longevity" or philosophers' stone, accomplish the transmutation into gold, and attain ultimate wisdom. It supposedly involves the manufacture of several substances with unusual properties, as well as improvement of the alchemist. Some alchemical sources treat the various substances, equipment and processes in an allegorical sense, as metaphors for a spiritual discipline.
Practical alchemy, on the other hand, can be viewed as a protoscience, the precursor to modern inorganic chemistry, having provided many procedures, equipment and names of substances that are still in use.