Trial by Fire
Lead oxides. The 16th-century Black Dragon experiment yields lead (II) oxide, the yellowest. (Andrew Lambert/Photo Researchers, Inc.)
I am a historian by training rather than a chemist, but right now I feel like a bit of both. Garbed in white lab coat, vinyl gloves, and goggles, I peer into the fume cupboard, where a Bunsen burner is heating a glass flask containing lead acetate. So far, so good: the white crystals have transformed into a blackish powder, and at the far end of a condensing tube a receiver has filled with thick, white smoke, exactly as described in my instructions. Not bad, given that this experiment has been pulled from a book more than 400 years old.
This might just be another day in the lab at the Department of Chemistry at Cambridge University—except for the BBC film crew recording my every move and the fact that my real background is in reading medieval manuscripts.
Under the expert supervision of chemist Peter Wothers, I have been trying to recreate some of the remarkable phenomena described in medieval alchemical treatises. The alchemists I study had ambitious goals: among them, the creation of the philosophers’ stone, capable of transmuting base metals into gold and silver; and medicinal elixirs for prolonging human life. Although their efforts failed to produce gold, many of the practical processes they describe can be deciphered and even replicated: from distilling acetates to manufacturing mineral acids.
I am not the first to try this: historians of science have long been intrigued by the possibility of recreating past experiments and technologies. Following historical recipes and experimental instructions can help plug gaps in our knowledge of the past by recovering details of materials and techniques that were never recorded in writing because that knowledge was simply taken for granted in its own time. The results can make us question some of our assumptions about the “impossibility” or “irrationality” of past science.
Alchemical recipes present particular problems for reenactment because the recipe makers often deliberately disguised the identity of their essential ingredients and processes. Sometimes the only way to test my interpretation of these recipes is to try to repeat them. Since first entering the lab in the summer of 2011, I have been trying to do just that.
In my first laboratory recreation I attempted to trace a mysterious ingredient referred to in alchemical texts as “sericon.” English alchemist George Ripley described this metallic body in the Marrow of Alchemy (1476). Other clues suggest that Ripley’s sericon was in fact a lead compound, dissolved in distilled vinegar to make a white gum—a substance modern chemists would equate to sugar of lead, or lead acetate. However, historians have to be careful with matching old and new terms too closely. “Lead acetate” would have meant as little to Ripley as “sericon” would to a present-day chemist. So rather than ordering pure lead acetate from a catalog, I’ve been studying how to make it the old-fashioned way, following Ripley’s instructions. Even then, my homemade sericon will likely differ from Ripley’s lead in exact composition and purity, which might affect my experimental reenactments.