Hóng qiān rù hēi qiān jué 紅鉛入黑鉛訣

Instructions on Inserting Red Lead into Black Lead

Anonymous; Táng

A short Táng alchemical instruction-text on the reaction of red lead (hóng qiān 紅鉛 = lead tetroxide, Pb₃O₄) into black lead (hēi qiān 黑鉛 = metallic or sulfide lead). Preserved as DZ 941 / CT 941 (Dòngshén bù, Zhòng shù lèi 洞神部眾術類).