Historical or fantasy term for the medieval proto-science of transmuting base metals into gold and seeking the philosopher's stone. Not used for modern chemistry.
In medieval Europe, alchemy was actively studied.
He devoted himself to alchemy and sought the philosopher's stone.
化学 means 'chemistry' as a modern science, distinct from the historical/mystical practice of alchemy.
Compound of 黄金 (おうごん, 'gold') and 術 (じゅつ, 'art, technique'). The exact historical derivation is uncertain; the spelling is conventionally associated with the meaning 'alchemy'.