Note: 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 similar Qianlong marked zhadou donated by Mrs. Edward L. Brewster is in the Walters Art Museum, Baltimore, Maryland (no. 47.689). A mallet-shaped vase of imitation realgar, with a Qianlong mark, from the Water, Pine and Stone Retreat, was included in the exhibition, Arts from the Scholar's Studio, The Oriental Ceramic Society of Hong Kong and University of Hong Kong, 1986, illustrated in the Catalogue, no. 94 and sold at Sotheby's Hong Kong, 8 October 2009, lot 1802, together with a Qianlong-marked realgar glass dish, lot 1809; a realgar glass censer from the same collection, sold at Sotheby's Hong Kong, 8 October 2010, lot 2219. A facetted bottle vase, Qianlong mark and period, in imitation realgar from the Walter and Phyllis Shorestein Collection sold at Christie's Hong Kong, 1 December 2010, lot 2925. 

Christie's. Important Chinese Ceramics and Works of Art, 1 June 2011, Convention Hall