Jīn líng zǐ 金陵子 (“Master of Jīn líng [= Nánjīng]”) was an early Northern-Sòng Daoist alchemist, author of KR5c0307 Lóng hǔ huán dān jué 龍虎還丹訣 (“Instructions on the Dragon-Tiger Return-Elixir”), traditionally dated 1042 (Qìng lì 2). The “dragon-tiger” (lóng hǔ 龍虎) pair denotes lead and mercury (or yáng and yīn) in the alchemical lexicon.