Alchemy is famous for its spectacular, allegorical images, in which chemical substances and processes are frequently depicted as human and animal figures, from battling dragons to the famous “chemical wedding.” But can this imagery tell us anything about how chemical processes were actually practiced and understood – and how can we tell the difference between experimental information and fantastical speculation? This talk will trace how practitioners in medieval and early modern Europe – especially in England – manipulated visual imagery in order to signal their place within ancient genealogies of knowledge, while also advertising new practical developments. Drawing on my own attempts to reconstruct historical experiments in a modern laboratory, I ask how these practitioners used images to promote alchemical projects to readers and patrons, even as they struggled with the dual challenge of reproducing accurate images on the page, and authentic chemical effects in the laboratory.