No annotator of Jonson's play The Alchemist has looked very deeply into the mediæval and Renaissance alchemical treatises current in Jonson's day for material in illustration and explanation of the speeches in the alchemical episodes of the play. For the most part, it is true, alchemical lexicons are all that is needed to define specific terms and to indicate their relationship to the theories and practices of the alchemists. But certain of the speeches of the play take on a new and fuller meaning when read against a background of some knowledge of this body of alchemical literature.