By Anke Timmermann
The scene seems almost idyllic: a stone basin in a green landscape, a stylised cloud floating above with the heads of three blond, chubby cherubs. But then we realise that the sweet, angelic faces are spitting a greenish-blue liquid into the tub, from whence it flows through a spout into a glass vessel. This means business!
The business at hand is the manufacture of the philosophers’ stone as outlined in the Rosarium Philosophorum, a popular alchemical tractate first printed in 1550. It represents one of the increasing number of illustrated alchemica that emerged from the fifteenth century onwards. Manuscript pages came to life with pictures of alchemical metaphors previously confined to descriptions. Colourful animals or humanoid figures (representing substances) were now shown engaged in activities (chemical processes and reactions), from knowing each other in the Biblical sense to mutual ingestion, in fiery or watery environments alike.
But, as exciting as this development was, alchemical practitioners still needed to translate imagery into practical terms to make sense of these ‘visual recipes’. Like the interpretation of recipe texts, and especially in combination with verbal recipes, this proved to be a difficult task. Today it is historians who try to find a recipe for the meaningful description and analysis of alchemical images. Here the little flask above, gathering the angelic fluids so faithfully, demonstrates how complex the business of alchemical history can be.
Glass vessels feature prominently in alchemical images from the late medieval and early modern period. The image above might indicate the use of an actual glass flask in this step of the manufacturing process, or, more likely, simply be intended to conjure up the mental image of gathering liquids with any appropriate vessel. However, in many visual alchemical scenes such as the Splendor Solis series or the Ripley Scrolls, drawn glass containers were clearly not intended to represent actual equipment, but rather to provide a visual frame for a process depicted in figurative form.
The translucence of glass benefited the artist aiming to reveal alchemical processes within a conceptual, as opposed to actual, space. By contrast, in actual laboratory practice, glass vessels were generally only used for distillation “where they may be used without fear of breaking or melting”. What we see, and what contemporary readers saw, in these ‘visual recipes’ is not an object, but a concept.
A much more pragmatic depiction of a similar flask may be found alongside Albertus Magnus’s appropriately-named Straight Path in the Art of Alchemy in GUL MS Hunter 110. This manuscript is roughly two hundred years older than the copy of the Rosarium Philosophorum above. Instantly recognisable as a receiver for distilled liquid, drawn complete with the entire apparatus, this flask nevertheless surprises in comparison with the previous image: this illustration does not show any liquid either before or after distillation. Such detail would have been realistic, but perhaps unnecessary for contemporary readers to understand the experimental setup.
Our final image could be mistaken for a regular kitchen if it weren’t for the distilling apparatus shown in the foreground. This piece of equipment was familiar to readers who had an alchemical background from practical manuscripts (like the previous one), but also to those employing distillation for medicinal or other purposes. This image reminds us of the intersection of alchemical recipes with those of other recipe literatures, in word and image.
What is particularly wonderful about this image is a detail that might be overlooked when considered in isolation from the other illustrations: the liquid in the receiving vessel is shown to stand at an even, calm level, while the liquid in the heated vessel is boiling, bubbles clearly visible. The present, nervous reader of this manuscript cannot help but worry about the stability of the glass, which could melt or break at any moment. It is only in comparison with other flask depictions that this detail emerges.
Questions about different purposes of illustration as well as local, temporal and individual preferences in visualising different aspects of the alchemical work come to mind. But is this a detail contemporary readers would have picked up on?
Well, now I see it. But maybe I shouldn’t.
My focus on the flask, just for the purposes of this blog post, was inspired by Tillmann Taape’s excellent recent post on distillation.
 Two seminal articles in this area are Barbara Obrist, ‘Visualization in Medieval Alchemy’, HYLE-International Journal for Philosophy of Chemistry 9 (2003), 131-70; see also Obrist’s earlier oeuvre on alchemical images. And Christoph Lüthy and Alexis Smets, ‘Words, Lines, Diagrams, Images: Towards a History of Scientific Imagery,’ Early Science and Medicine 14 (2009 ), 398-439.
 This manuscript is described and analysed in Paul Engle, “Depicting Alchemy: Illustrations from Antonio Neri’s 1599 Manuscript”, in Dedo von Kerssenbrock-Krosigk, ed., Glass of the Alchemists (New York, NY, 2008), 48-61.