Trial by Fire

Over the past year Jennifer Rampling has been trying to re-create some of the remarkable phenomena described in medieval alchemical treatises.

By Jennifer Rampling | December 12, 2012

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.

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Lead oxides. The 16th-century Black Dragon experiment yields lead (II) oxide, the yellowest.

Andrew Lambert/Photo Researchers, Inc.

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.

A late 16th-century recipe, later published as The Bosome Book of Sir George Ripley (1683), describes the sericon approach in more detail. Thirty pounds of sericon must be dissolved in thirty gallons of vinegar. The resulting gum (or “Green Lion”) is then heated in a furnace. The recipe warns that the first vapor to come off will be “a faint Water. . . . Let it waste away.” The vapor is actually the water of crystallization boiling off, after which the white gum begins to blacken. Then the real business starts: “When you see a white Smoak or fume issue forth, then put too a Receiver of Glass.” This “white smoke” condenses to form the liquid the recipe calls the “blessed water.” This “water” is an important ingredient: the next step in making an elixir capable of transmuting base metals into gold. However, the recipe isn’t yet finished with the black powder—the “Black Feces” or “Black Dragon”—left in the flask. When the powder is tipped onto a marble block and ignited with a hot coal, the recipe promises that “the Fire will glide through the Feces within half an Hour, and Calcyne them into a Citrine Colour, very glorious to behold.”

In May 2012 I was contacted by a BBC4 producer. He hoped to film an alchemical experiment for a documentary about gold: A History of Art in Three Colours. Without much time to prepare historically authentic apparatus, Wothers and I end up doing a test run of the Black Dragon experiment, with a Bunsen burner standing in for an alchemical furnace and with off-the-shelf lead acetate. Sure enough, my receiving flask soon fills with the “white smoke,” which condenses to form the “blessed water.”

Of course, not everything goes according to plan. The flask sticks fast to the condensing tube. Had I used an authentic alchemical “lute” to seal my vessel rather than modern quick-fit glassware, this problem might have been avoided. However, the alchemists are clear on what to do in such cases: break the glass. Hoping that the heated lead powder does not immediately ignite when exposed to air (which it has a tendency to do), I smash the flask with a hammer, to the delight of the TV crew.

Fortunately, the Dragon waits for the hot coal before igniting. To our surprise, even using this modern setup, we reproduce the effect described in the 16th-century text: the hot coal touches the black powder, brightening it into golden yellow—a color that seems to flow across the surface of the lead.

Watching the leading edge of the transmutation sweep across the lead’s surface, I wonder how this effect appeared to a 17th-century audience. In modern terms some finely divided lead is simply reoxidizing into litharge (PbO). Yet, watching as the Black Dragon tinges into gold, it is hard to blame earlier “chymists” for taking such remarkable, and replicable, demonstrations as evidence of the transformative power of their art.