Alchemy was a group of philosophical doctrines, magical practices and direct investigation of nature whose aim was to find the Philosopher’s Stone (in the show, the Mage Stone), the principle that could reveal the secrets of life and transform the very essence of things, turning base metals into gold. Another goal of alchemy was to create a “Panacea”, a remedy that supposedly would cure all diseases and prolong life indefinitely.
The equipment of Edwin Muirden, a sorcerer who infiltrated Camelot castle by pretending to be a physician who possessed a remedy to cure all ills, had originally been designed for alchemy. When Edwin gave Merlin this information, he immediately associated it with the making of gold. The warlock used these instruments in his magical and scientific experiments (A Remedy to Cure All Ills).
When the Curse of the Unicorn was brought upon Camelot by Arthur, the kingdom’s water supplies were turned into sand. Merlin tried to work his magic on a bucket of sand and change it back into water with the spells “Gréot gecumen lecan. Gecumen gé drý wæter”, but Anhora’s and the cure’s magic was more powerful than his (The Labyrinth of Gedref).
The Mage Stone, wonder of the ancients and lost for a thousand years or more, could theoretically give the bearer the power of transformation. With it a man can alter the very essence of things, turning a lump of lead into pure and priceless gold, the true power of alchemy.
The Mage Stone was wielded by the renegade sorcerer Tauren, who fulfilled part of the alchemists’ great work with an experiment at Tom’s forge. Tauren, using the magic of the Mage Stone, turned the lead Tom was pouring into a mould into pure gold with the spell “Ferian æt gylden. I búgan þéos. Ferian æt gylden”; his intentions were to use the corruption at the heart of Uther’s kingdom and the abundance of gold he could produce to buy himself into the King’s chambers, even to the King himself (To Kill the King).