After the Second Nun's Tale the host asks the Canon and his Yeoman to tell a tale. Both men are alchemists and the Yeoman works for the Canon. The Yeoman starts the tale explaining he's worked for the Canon for several years and decides to quick. He calls their profession "slippery science" and that they have no money because their alchemy attempts always fail. Before the Yeoman divulges all their secrets, the Canon steps away embarrassed. The tale starts with a a canon who cons a priest into thinking he's taken quick silver and turned into real silver. He continues with his trick, convincing the priest he's also turned chalk and a twig into real silver. The Canon agrees to reveal his secret for forty pounds to the priest and the con is complete. The Yeoman, who is obviously a disgruntled employee, bashes the alchemy profession even more. Check out these words of the Yeoman.
695 And though you prowl, you never gold shall find;
696 You are as bold as Bayard is, the blind,
697 That blunders forth and thinks of danger, none;
698 He is as bold to run against a stone
699 As to go ambling down the broad highway.
700 And so fare you who multiply, I say.
701 If your two fleshly eyes can't see aright,
702 Look to it that your mind lack not for sight.
703 For, though you look about and though you stare,
704 You shall not win a mite in traffic there,
705 But you shall waste all you may scrape and turn.
706 Avoid that fire, lest much too fast it burn;
An Alchemist seemed more like a magician than anything else. I always find alchemy in general fascinating What about you?