This article presents and analyses chapter XLVI from the Tractat de les penes particulars d’infern by Catalan franciscan friar Joan Pasqual, written soon after 1436. This chapter, “Del cercle de l’alquímia”, includes an exemplum which is doubly significant: on the one hand, it documents the alchemic legend in the Plantagenets’ court during the 14th and 15th centuries; on the other hand, and most importantly, it is a new testimony of two narrative motifs of Eastern origin: the fake alchemist and the king (Thompson, K.111.4; Tubach, 89), and the account-book of mistakes or fools (Thompson,J.1371). After introducing the medieval witnesses of these motifs, the alchemic legend of Ramon Llull and king Edward of England, and Joan Pasqual in his historical context, the essay offers an edition of the Catalan text and a thorough comparative analysis with the more evident witnesses within the tradition: for the whole story, the Kit?b al-mukht?rf? kashf al-asr?r (IX, 9) by Al-Jawbar?, the exemplum XX in the Libro del conde Lucanor by don Juan Manuel and the anonymous Libro del caballero Zifar; also Fèlix or Llibre de meravelles (VI, 36[4].47-68) by Ramon Llull for the motif of the alchemist and the king, and the novella LXXIV in the Novellino Borghini for the motif of the account-book of mistakes of fools. The conclusions of this analysis allow to trace the outline of a very useful stemma narrationum to discuss the position of Geoffrey Chaucer’s The canon’s yeoman’s tale within this tradition.