Leona Constantia

Leona Constantia was a 17th-century alchemist and author. She wrote the alchemical treatise, (The Sunflower of the Wise), which appears to have been first published in 1704.

Her 136 page book offers instructions for preparing the philosopher's stone, along with ethical warnings and admissions of the author's "errors".

Scottish chemist John Ferguson, in his 1906 Bibliotheca Chemica, indicates that Constantia was a pseudonym of English mystic Jane Leade (1623–1704), but also notes that none of Leade's other publications dealt with chemistry. An essay published in the 1794 Hermetischen ABC also identifies her as Leade. In the 18th century, Johann Friedrich Henkel (1678–1744) and Johann Friedrich Gmelin (1748–1804) agreed that she was from Clermont in central France, with Henkel identifying her as a baroness. More recently, researchers have conjectured that she was Sophie Elisabeth von Clermont.