Like other glass vessels of the Qianlong period, this vase is imitating a natural material, in this case the mineral realgar (arsenic bisulphide, xionghuang), which was an important substance in Daoist alchemical studies. As it was soft and disintegrated into a poisonous powder, imitations in glass could be safely admired and handled. A pair of similar vases imitating realgar, also with Qianlong marks, in the collection of James Biddle, is illustrated by C. Brown and D. Rabiner, Clear as Crystal, Red as Flame, China Institute in America, New York, 1990, no. 29. A pair of purse-shaped glass vases imitating realgar, dated to the 18th century, in the Shuisongshi Shanfang Collection, is illustrated by E.B. Curtis (ed.), Pure Brightness Shines Everywhere: The Glass of China, 2004, p. 73, fig. 8.9. Also illustrated, fig. 8.8, is a small imitation realgar wine cup, one of a set of ten brought to Denmark in 1732, and now in the Royal Danish Kunstkammer.