be seen as an art. Among many practitioners, a significant number of women were known to have mastered this art. The earliest recorded woman alchemist had the family name of Fang (), and lived around the first century B.C. Raised in a scholarly family skilled in the alchemical arts, she studied alchemy with one of the Emperor Han Wu Ti's spouses, and therefore had access to the highest levels of society. Fang was credited with the discovery of the method to turn mercury into silver. It was believed that she may have used the chemical technique of silver extraction from ores using mercury, where pure silver residue is left behind from the boiled mercury. Fang's husband was Cheng Wei (；see :zh:程偉). Details of Fang's life were recorded by author and alchemist Ge Hong. Keng Hsien-Seng (circa A.D. 975) was another female alchemist who, according to the science writings of Wu Shu "mastered the art of the yellow and white [alchemy] with many other strong transformations, mysterious and incomprehensible". Wu Shu also described Keng as being acquainted with other Taoist techniques and was believed able to control the spirits. She also mastered the transformation of mercury and "snow" into silver, probably using the technique of extraction of silver from its ores, as well as using a primitive type of Soxhlet process to continuously extract camphor into alcohol. Other female alchemists who have been recognized in Chinese literature are Pao Ku Ko (third century A.D.), Thai Hsuan Nu, Sun Pu-Eh (12th century), and Shen Yu Hsiu (15th century). See also Chinese alchemical elixir poisoning Alchemy and chemistry in medieval Islam Cold-Food Powder Yellow Court Classic References Additional bibliography Jefferson, R.B., Doctrine of the Elixir. Coombe Springs Press 1982. . Miller, James, and Elijah Siegler. "Of Alchemy and Authenticity: Teaching About Daoism Today". In Teaching Theology and Religion, Vol. 10 (2007): 101-108. ISSN 1368-4868. Pregadio, Fabrizio. The Seal of the Unity of the Three: A Study and Translation of the Cantong qi, the Source of the Taoist Way of the Golden Elixir. Mountain View: Golden Elixir Press, 2011. . Partial online version, retrieved March 29, 2012. Pregadio, Fabrizio. The Way of the Golden Elixir: A Historical Overview of Taoist Alchemy. Mountain View: Golden Elixir Press, 2012. [PDF, 60 pp., free download.] Pregadio, Fabrizio. Chinese Alchemy: An Annotated Bibliography of Works in Western Languages. Mountain View: Golden Elixir Press, 2009. Radcliffe, Jeannie. "Alchemy and