Of ancient texts on Greek alchemy there survive two papyri, three vast corpora of differing date and content, and a few isolated treatises. (a) Papyrus X from Leiden and the Stockholm papyrus can be dated by handwriting to the early 4th cent. ce. They are two parts of the same collection of recipes for gold, silver, precious stones, and purple, compiled from older works and, in particular, citing *Democritus. (b) Corpus M, the MS Marcianus graecus 299, now in Venice, was copied in the 11th cent., probably in Constantinople. Damaged, although a full table of contents survives, it is a compilation of texts probably formed at the court of the emperor Heraclius (7th cent.) on the initiative of one Theodorus, a court dignitary and associate of Stephen of Alexandria. (c) Corpus B, the MS Parisinus graecus 2325, now in the Bibliothèque Nationale in Paris, from the 13th cent., of unknown provenance: a collection of texts perhaps formed in the time of *Psellus (11th cent.