Donkey-hide gelatin

Donkey-hide gelatin or ass-hide glue (Latin: colla corii asini) is gelatin obtained from the skin of the donkey (Equus asinus) by soaking and stewing. It is used as an ingredient in the traditional medicine of China, where it is called ejiao (simplified Chinese: 阿胶; traditional Chinese: 阿膠; pinyin: ējiāo), meaning "gelatin of Dong'e County".

The gelatin is produced in several coastal provinces of China: Jiangsu, Zhejiang, Shandong. Shandong's Dong'e County is the source of the name "ejiao".

According to a ca. 1723 account by the French Jesuit Dominique Parrenin, there was a well in Dong'e which was normally kept closed and sealed, and which was only opened when water was taken to be used in preparation of ejiao for the emperor's court.