Jintong yaolüe 浸銅要略

Jintong yaolüe 浸銅要略 "Important facts of copper-soaking" was a book on wet-copper production written by Zhang Qian 張潛 during the Northern Song period 北宋 (960-1126).

"Wet copper" (jintong 浸銅) or "gall copper" (dantong 膽銅) refers to refined copper, which is obtained from cupriferous substances by means of solution in vitriol water and precipitation on iron (hydrometallurgical methods). In China, the technique began to be employed on a large scale around the end of the eleventh century and almost wholly vanished again after the end of the Song period. By the second half of the 12th century, wet copper accounted for the lion's share of the urgently needed mint metal and developed into one of the state's most essential industries. (Jost 2014)

The method was first tested by Zhang Qian in 1086 in Raozhou 饒州, and in 1094 in the Xingli Factory 興利場 in Dexing 德興. The factory in this district yielded an annual output of 51,000 jin 斤 ("pounds") of copper. The practice of wet-copper production was described by Zhang in a book that is mentioned in the bibliographical chapters (202-209 Yiwen zhi 藝文志) of the Songshi 宋史. During the Yuan period 元 (1279-1368), Zhang Qian's descendent Zhang Li 張理 presented the book to the throne, and in 1352, the Yuan court made Zhang Li the supervisor of the factory. Zhang asked Hanlin Academician (Hanlin xueshi 翰林學士) Wei Su 危素, courtesy name Taipu 太樸, to write a preface for the book. While Zhang's book was lost after the end of the Yuan period, Wei's preface has survived in his collected writings Wei Taipu wenji 危太樸文集. The preface gives a brief introduction to the topic and describes in short words some aspects of the production.