Illustration of 'winter frost water' (Dongshuang shui) from Shiwu bencao (Materia dietetica), a dietetic herbal in four volumes dating from the Ming dynasty (1368-1644) © Wellcome Collection, London.

The identity of the author and artists is unknown. It contains entries on over 300 medicinal substances and is illustrated by almost 500 paintings in colour. Frost (shuang), i.e. frozen dew, was collected by brushing it up with chicken feathers, and was then sealed in bottles for later use. The illustration shows a man climbing a ladder to gather frost from a roof. The text states: Winter frost water is cold in thermostatic character and non-poisonous. It is used to relieve alcoholic heat (jiure), cold damage and heat ailments.