Around the Table: Research Technologies

This month on Around the Table, I am speaking with Helen Davies and Alexander Zawacki, Program Coordinators of the Lazarus Project and PhD students in English at the University of Rochester. This month on the Recipes Project, we’ve explored all kinds of ideas about texture. Now, we’ll get a chance to learn about digital textures, and how technologies like multispectral imaging can help scholars unearth new information about manuscripts. Those of us dealing with manuscript recipes from any time period are accustomed to erasures, stains, and layers of writing. Helen and Alex provide information about the ways in which multispectral imaging can help us interpret these elements of our sources.

Tell us a bit about the Lazarus Project. Do you work with materials from a specific time or place? With what sorts of projects and partnerships has your lab been involved?

The Lazarus Project is a multispectral imaging endeavor located at the University of Rochester. We’re a mix of professors, graduate students, and undergraduates from a range of different fields all working to use cutting-edge technology to digitally recover lost texts and images. Many of us — Helen, Alex, PhD Candidate Kyle Huskin, and our advisor (and the director of the project) Gregory Heyworth — are medievalists, and so many of projects tend to focus on objects from that time period in Western Europe, but we’ve also worked on Biblical manuscripts from Egypt, pre-Columbian material from the Americas, postcards sent from concentration camps and censored by the Nazis, and eighteenth-century musical scores from Germany. We’ve partnered in the past with (to name just a few) the United States Holocaust Museum, the Folger Library, the Beinecke Library, the Saxon State and University Library Dresden, the Vercelli Chapter Library in Italy, and the Bodleian Library.

How does your lab select items to analyze? Do libraries and organizations reach out to you, or do you seek out specific items and projects?

A bit of both. Sometimes we’ll find objects that we particularly want to work on, and set about applying for grants and searching for funding to make that happen. Other times institutions or even private individuals will reach out to us about an object in their care that they would like to have imaged.

Could you explain how multispectral imaging works? Can you provide a few examples of what scholars can learn about books with this technology?

We take an object — a manuscript, for example — and photograph it first under discrete wavelengths of light, moving from the ultraviolet through to the infrared. Then we take another series of images under only ultraviolet, violet, and blue light, which induces fluorescence in the object, like when you wear a white t-shirt under a blacklight. We use filters to separate out different wavelengths from the fluorescence that the object emits, trying to squeeze as much data out of it as possible. Lastly, we take a final group of photographs while shining light upwards through the manuscript, which has the potential to reveal “ghost letters” — places where the ink has been removed, but the parchment has thinned enough to reveal where it used to be.

Photographing the object is only the very tip of the iceberg, though — almost never do any of the images reveal all or even much of what we’re looking for. Next, we process the images using software originally designed to analyze satellite and aerial imagery. This can be a very laborious and time-consuming process.

Our goal is to recover texts and images that have been lost to time and damage. Palimpsests are a great example of the kind of thing that scholars can learn using this technology. In the medieval period, people would sometimes erase entire manuscripts by scraping or washing the parchment clean, and then re-use the pages to make a new book. The “undertext” — the book that was erased — is often illegible, far too faint and obscured by overwriting to read. We try to make that undertext visible again, usually for the first time in centuries. Other times we work on objects that have been damaged by fire, water, chemical staining, or simple fading, all with the goal of bringing scholars new texts to work on and study.

During a July 2019 workshop on Spectral Imaging in Cultural Heritage, the Lazarus Project team shared information about imaging methods with a group of participants. Participants at the workshop could see how chemical reagents are used on palimpsested manuscripts. Pictured here: pumice is used to palimpsest parchment, and then a reagent reveals the erased writing.

As you know, our readers deal with recipes of all kinds (medical, household, culinary, alchemical, etc.) We encounter strange marks and stains all the time in our books! What can multispectral imaging tell us about those marks and stains?

Multispectral imaging can help readers work with a variety of stains and marks in a variety of ways. Firstly, we can help you see through them. MSI can help readers see underneath the stains. This can be very important in manuscripts whatever been treated in chemical reagents. As you and your readers likely know, chemical reagents were widely used for a time in order to bring out ink that had faded. Yet this momentary gain in legibility was frequently followed by long term damage to the manuscript. MSI can help digitally reverse these stains. Hyperspectral and other imaging modalities can be leveraged to look at material composition of stains. Multispectral, however, mostly helps with legibility rather than material analysis. A group of scholars has recently tried to push the material analysis capabilities in new directions through the Library of Stains project.

At the workshop, an image of the Rotovap system distilling the wine + oak gall solution.

What kind of training or partnerships might be necessary for a humanities scholar without a digital background to incorporate imaging into their research?

An interested humanities scholar would first need to either purchase a multispectral imaging system or partner with a group or institution that owns one. This partnership could take the form of receiving some training in operating the technology (unless the group would be doing both the imaging and the processing, as we often do) or being lead scholar on the project.  Training could incorporate learning more about MSI on site or image processing training. There is a range of software available for processing including ENVI (which we use), Matlab, Python or Image J (for which imaging professionals built various custom toolkits). A lead scholar partnership involves a humanities scholar reaching out to us for imaging, working with us to secure funding for the project, and then this individual driving the research. We will work with them to ensure we get as much data as possible from an item, but they lead the transcription, translation and examination of the document. This gives non-digitally inclined scholars the opportunity to work with multispectral images and recovered texts.

How did you become interested and involved in digital humanities and the Lazarus Project?

All of our team members have come to the Lazarus Project through different routes.

Helen: I had the opportunity to photograph early print books in the York Minster Library while working on my MA in Medieval Studies. This led to me pursuing a digital humanities MA and further imaging jobs. Eventually, a friend of a friend asked me to do some work for Lazarus and then Greg encouraged me to apply for a PhD to continue learning from and working with the project.

Also at the workshop, Alex Zawacki transfers the reagent.

Alex: I found out about the project as a first year PhD student at the University of Rochester. I was fascinated by the idea of recovering lost texts. I started working with the project to see what we could find, and I am now cultivating my own projects to search for lost material in my own field.

Do you have any favorite Lazarus Project items you’ve worked with, so far?

We all have our own individual favorites we have worked on in the past.

Helen: My all-time favorite is the damaged medieval world map in Vercelli, Italy. There are only a handful of large scale medieval wall maps to survive (others have fallen victim to bombs, binders and other forms of destruction). The map in Vercelli survives, but has been largely unreadable. We have imaged it, recovered it, and, I am happy to report, as of last week I have created an entirely new digital facsimile of the document. However, I have loved getting the chance to work on a variety of objects from ancient coins to Old English poems to early modern globes.

Alex: I’m torn between the Codex Boenerianus, the Black Book of Camarthen, and a single manuscript fragment from the University of Rochester’s Rare Books and Special Collections department. The latter had been used as a binding fragment and was terribly faded and stained. No one had been able to read any of it in the 50 years that it had been in the university’s care. That one was particularly rewarding, as not only were we able to recover nearly the whole text, identify the work to which it belonged (Richard FitzRalph’s Summa Questionibus Armenorum), and trace some of its provenance and history as an object, we also found that it was the only witness to that text in a non-European library — and very possibly the oldest extant witness.

Thanks, Helen and Alex, for chatting with me about multispectral imaging! You can follow the Lazarus Project on Twitter @Lazarus_Imaging, Facebook @LazarusProjectImaging, and Instagram @lazarusprojectimaging. If you’d like to feature a project, scholar, or institution on Around the Table, please email Sarah Kernan.

Tales from the Archives: Drinkable Gold for the King of Siam

In my first months of co-editing duties here at The Recipes Project, one of my many delights has been the opportunity to dig back in our archives to rediscover posts I’ve loved over the years, to see them with fresh eyes. As a historian of Japan, I’ve looked forward to exploring and expanding our content on Asia, especially in global exchange. In that spirit, I bring you a classic post on European medicine in Siam (Thailand) from back in 2015, Tara Alberts’ “Making Drinkable Gold for the King of Siam.”

You may also notice several posts on a mini-theme of…shall we say uncomfortable recipes throughout the month of April, including historical treatments for lice and hemorrhoids already available to read (with more to come). Though I’d hardly put drinking gold at the same level of discomfort, and a fleck of gold leaf in a cocktail can still be a decadent indulgence today, I’d hate to see what a bellyful of Parisian golden medicine would do to a poor king’s stomach. Salud!

Making Drinkable Gold for the King of Siam

By Tara Alberts

In a previous post I discussed how early modern Catholic missionaries sought to showcase the most up-to-date European medicines to impress their target audiences. This was also a key strategy used to gain access to royal courts throughout Asia.

At the court of King Narai (r. 1656-88) of Siam, for example, Europeans joined experts from China, India, and elsewhere in Southeast Asia to provide medical advice to the royal family.  Narai’s court was a cosmopolitan place: the king was keen to hear about foreign technologies and theories, and to encourage foreign trade. The French missionaries of the Société des Missions Étrangères de Paris (MEP) were determined to take advantage of the opportunities that this offered.

Narai receiving the French Embassy, 1685. Wikimedia Commons
King Narai receiving the French Embassy, 1685. Wikimedia Commons

This could be easier said than done. It’s likely that the job of concocting remedies fell to René Charbonneau (1643-1727), a lay auxiliary to the MEP who had trained as a surgeon. In a 1677 he wrote a frustrated letter to a friend in Paris pleading for an easy-to-follow recipe written in French for aurum potabile. ‘The king has asked for drinkable gold’, he wrote ‘but we have not been able to manage it. […] Please write down in a letter the method of making it and purifying it for use, and the manner in which it is taken, written out in full in clear French and not in Latin and not in terms of chemistry as I am not versed in that art.’ (Archives des Missions Étrangères [AMEP] vol. 861, p. 41).

Gold-based medicines had ancient precedents in various European and Asian medical traditions. Like many putative panacea they enjoyed a renaissance in Europe in the late sixteenth and early seventeenth seventeenth centuries. [i] There were innumerable recipes available to create aurum potabile, often using gold flakes or powder alongside other expensive ingredients including precious stones, unicorn horn and spices.

Yet since the sixteenth century, many writers had been extremely skeptical about whether such cures could possibly be of use. The chemist Nicolas Lefebvre, in his Traité de la Chymie (1660), denied that they could have any effect on the human body. Mixing gold leaf into medical concoctions and powders, he asserted, was an ‘abuse in Pharmacy that the Arabs have introduced’ (p. 801). Such medicaments could not be effective as the human body contained nothing capable of breaking the gold down. Lefebvre doubted whether any efficacious cure could really be created from gold, but like other compilers of alchemical compendia, he provided a range of common recipes to purify and use gold in a more sophisticated manner.

An alchemist making gold. Oil painting by Hendrik Heerschop. The Wellcome Library, London
An alchemist making gold. Oil painting by Hendrik Heerschop, 1665

It seems that the MEP were attempting to use these sorts of alchemical methods to create a ‘true’ drinkable gold (rather than just creating a medicinal draught with added gold flakes) and that this was proving difficult. MEP missionary Charles Sevin (?-1707) blamed the equipment available in Siam. He explained in a letter to his Parisian superiors that they had brought the necessary ingredients to make the king some huile d’or potable, but the glass retorts they acquired there all shattered before they reached the necessary temperatures. (AMEP, vol. 851, p. 190).

Others confessed that their ignorance of alchemical processes was hindering progress. Charbonneau mentions that he had with him Christophe Glaser’s Traité de Chymie (1667). In this, Glaser explains several different ways of purifying gold, and offers several different methods for rendering this purified gold usable as a medical preparation through fulmination, calcination with mercury, or dissolution in the aptly named ‘royal water’ (eau régale or aqua regia – nitrohydrochloric acid). One recipe for a draught containing ‘diaphoretic gold powder’ for example, recommends that after purification the gold should be dissolved in three drams of royal water to which is added a dram of refined saltpeter. This liquid should then be used to soak small pieces of linen, which, once dried, should be burnt. The resultant ashes should be collected carefully using a hare’s foot or a feather and then used to make a pill or a draught using a small amount of wine or bouillon.

Glaser’s stated aim in writing his Traité was to set out the principles and practices of chemistry in plain language, but Charbonneau complained that he found Glaser’s text confusing. He and his confrères had had some success when they attempted to follow Glaser’s instructions with regards to purifying tin, but they were not confident enough to give a demonstration, nor, presumably, to waste their supplies of ingredients needed to make impressive remedies for the king.

There was a clear incentive to make a particularly impressive version of drinkable gold which would showcase the effectiveness of exotic European recipes, and by extension other branches of European knowledge. Yet even the most up-to-date texts explaining how to create these remedies were useless without the necessary skills and equipment to put the theory into practice. No wonder then that MEP superiors in Siam began soon to lobby for missionaries and lay helpers who were skilled in alchemy to be sent from Paris.

[i] Informative overviews of the history of pharmaceutical gold are provided here by R. Console, and here by M. Hendriksen.

Archaeology and early modern glassmaking recipes: The case of Oxford’s Old Ashmolean laboratory.

By Umberto Veronesi

Crystal blown bottle decorated with milk glass festoon (festoni di lattimo), c. 17th c., Venice.  Image courtesy of Wikimedia Commons.
Crystal blown bottle decorated with milk glass festoon (festoni di lattimo), c. 17th c., Venice. Image courtesy of Wikimedia Commons.

The product of human ingenuity, glass perfectly embodies the alchemical power to imitate nature by art and since the Bronze Age it has proved an incredibly hard substance to classify. Although glass only requires sand, salts and the action of fire, a quick look at any recipe collection will reveal that glassmakers have used a vast array of ingredients depending on what materials were available to them and on the physico-chemical characteristics desired. Colours and opacity were provided by the addition of the right metallic oxides, but even a perfectly colourless glass required specific reagents.[i]

Here, I am going to explore three 17th-century recipes for white enamels, what Venetians called lattimo. Enamels are glass pastes that could be coloured according to the need and then used as paint or to counterfeit gems. There are plenty of recipes out there, many are listed in Antonio Neri’ L’Arte Vetraria. However, in this post I am going to take my start from a different set of “primary” sources, namely the very crucibles used to manufacture white enamel at one of Europe’s leading chymical laboratories, the Old Ashmolean in Oxford. The residues found stuck to the walls of the vessels (Fig. 1) contain the chemical fingerprint of the ingredients used. The analysis of small cross-sections of such residues with a scanning electron microscope (SEM) are therefore a way to explore the recipes.

Figure 2. Crucible fragments analysed with glassmaking residues.
Figure 2. Crucible fragments analysed with glassmaking residues.

The chemical composition of the three residues shows both similarities and important differences. All of them have high levels of silica, corresponding to sand, the main component of glass. To melt silica a fondant is essential, and it needs to be added to the crucible. Here, two residues (B and C) bear the traces of a potassium-based fondant, probably saltpetre or even salt of tartar. Residue A has sodium oxide instead, which means that a different fondant was, pure soda most likely. Recipe-wise, this is the first relevant difference. Next, a reagent must also be added in order to render the glass paste white and opaque. A look at the microstructure of the residues (Fig. 2-4) helps identify what such reagents were and what different choices were made[ii].A (Fig. 2). The white aggregates visible in cross-section are the remnant of a mixture made of lead and tin calcined and then added to the crucible. This, together with somewhat large grains of sand, would produce the required colour and opacity.

Figure 3. SEM image of residue A showing dark sand grains and remains of lead-tin calx used as opacifying agent.
Figure 3. SEM image of residue A showing dark sand grains and remains of lead-tin calx used as opacifying agent.

B (Fig. 3). Here too crystals can be seen scattered throughout the glass and, like before, these are responsible for an opaque white enamel. However, these are made of tin oxide only, indicating that in this case the calx did not contain lead.

Figure 4. SEM image of residue B showing the tin oxide crystals as opacifying agent.
Figure 4. SEM image of residue B showing the tin oxide crystals as opacifying agent.

C (Fig. 4). There seems to be a third lattimo recipe being tested at the Old Ashmolean. This is more than a simple variant because it used a wholly different type of reagent, the antimony ore stibnite. The glass is indeed rich in antimony oxide while the microstructure reveals small white opacifying particles. These are a compound made of calcium and antimony that form when stibnite is added to the glass and heated. Such recipe is less common in technical writings, but it is reported in Christopher Merret’s commentary to Antonio Neri’s glassmaking treatise.[iii]

Figure 5. SEM image of residue C, showing the small opacifying crystals of calcium antimonate.
Figure 5. SEM image of residue C, showing the small opacifying crystals of calcium antimonate.

From this necessarily brief survey we can see that there is more than one way to make an opaque white glass paste. What is interesting is that such diversity happened at one of the leading chymical laboratories of its time, giving us an idea of the experimental nature of this enterprise. Making glasses was certainly a way of investigating nature, of looking at how transformations come about. At the same time, it was a way to test recipes for the industry. In this sense, artifacts can become a powerful tool for the history of recipes, another way to enter the arena of artisanal knowledge.

[i] Cable Michael 2001, p. 307.

[ii] Neri’s recipes for white enamel can be found in: Cable Michael. The world’s most famous book on glassmaking. The Art of glass by Antonio Neri, translated into English by Christopher Merrett (The Society of Glass Technology, 2001), Book 3.

[iii] For a general survey on glassmaking I suggest chapters from: Janssens Koen (Ed.). Modern Methods for Analysing Archaeological and Historical Glass, 2013.

Umberto Veronesi  is a Ph.D. candidate at the Institute of Archaeology, University College London. His dissertation entitled, “The archaeology of laboratory experiments and early chemistry: Oxford to Jamestown and back” focuses on exploring the practice of alchemy through the lenses of the archaeological materials coming from early chemical laboratories and uses scientific archaeology as a means to inform historical research and questions. Veronesi received his BA in Archaeology from the Sapeinza Universita di Roma in 2013, and his MSc Technology and Analysis of Archaeological Materials from the Institute of Archaeology, University College London in 2014.

Making Mr. Song’s Cheeses

By Miranda Brown

The subject of this post may strike readers as odd. The combination of “Chinese” and “cheese” brings little to mind: neither memorable textures, nor fragrant flavors. Nothing, not even a single name like Parmesan or cheddar. The reason for the dearth of associations is obvious enough. Cheese is largely absent from the Chinese diet, nowadays found only in the periphery of the Chinese world, in places like Yunnan and Mongolia, where it is regarded as ethnic food for Tibetans and other minorities.

Yet things were different several hundred years ago. Chinese gastronomes once waxed poetic about the taste and texture of cheese, professing their preference for it over elaborate delicacies. One poet, living in the thirteenth century, extolled the flavor of cheese, saying, “No need for fancy morsels when there is cheese!”[1] Another, living a century later, asserted the superiority of dairy to bean curd. “While this old fellow is content with his tofu,” he wrote, “The delight gotten from cheese is double.”[2]  These early foodies related recipes for manufacturing fresh, non-melting cheeses like paneer and the secrets for creating stretched curds like mozzarella.

Over the last several years, I have experimented with recipes for Chinese cheese, attempting to recapture the flavors and textures of centuries past. One recipe, for stretched-curd “milk threads,” proved tricky. Preserved in a 16thc-cookbook, Song’s Instructions for Preserving Life (Songshi yangsheng bu 宋氏養生部), the recipe can be summarized like this:

  1. Heat cow’s milk until hot.
  2. Pour in a souring agent (akin to diluted vinegar), dripping it into the milk gradually.
  3. Once a curd forms, collect it with a cotton wrap and shape into a disc.
  4. Take the curd and place inside of a pot of scalding water.
  5. In a separate vessel of scalding water, press it into the shape of a thin sheet of coarse silk.
  6. Place the curd onto a stick, rolling and pulling.
  7. Put the curd inside the scalding water in the pot, rolling and pulling three to five more times while in the water.
  8. Roll out the resulting thread, placing it on a rack to dry in the sun (oil can be added to make the product smoother).[3]

This recipe assumes a working knowledge of the cheesemaking process. Hence, the omission of precise measurements. Readers must know beforehand the quantities of milk or souring agent, and the temperature of the milk or scalding water. Needless to say, this presents a challenge to a modern cook who is unfamiliar with cheesemaking.

My first attempts to produce the cheese failed, even with un-homogenized milk. The resulting curds, small and grainy, refused to stretch after being immersed in hot water. I sought help from Youtube, watching videos of Indian housewives making kalari, a non-rennet string cheese that was similar to Song’s stretched curd in terms of ingredients (cow’s milk, vinegar, hot water). I noticed that when coagulating the milk, the home cooks would test the temperature of the milk with their fingers, stopping the heating process once they could no longer keep their fingers in the liquid, rather than waiting for the milk to come to a soft boil as one would when making ricotta or paneer. This made me think that control of temperature was key to success, something hinted by Song’s own directions: heat the milk until hot, not boiling. Still, my subsequent efforts to make the cheese failed despite the care taken during the initial curdling process. I wondered if the pasteurization process, which requires that the milk be heated to at least 165° Fahrenheit, had something to do with my lack of success.

My breakthrough came during a trip to California, where I was able to purchase raw or unpasteurized milk. I heated a quart of the raw milk gently until hot (110° F), then poured in a little diluted vinegar and shut off the heat, all the while continuously stirring the milk. Within minutes, the milk transformed into one large curd.

Figure 1: Raw milk coagulated with diluted vinegar. Image courtesy of the author.
Figure 1: Raw milk coagulated with diluted vinegar . Image courtesy of the author.

I removed the curd and heated a pot of water to simmering, and immersed the curd into the scalding water for a few moments, removing it from the pot and kneading, repeating the process three times. Voilà, an elastic curd that stretched easily.

Figure 2: The stretched curd with the author, made with a quart of milk. Image courtesy of the author.
Figure 2: The stretched curd with the author, made with a quart of milk. Image courtesy of the author.

Looking back at the experience with Chinese cheesemaking, I can say that the success of my experiment depended on a variety of factors: knowledge of arcane texts, watching other cheesemakers at work, and many failed experiments in the kitchen.

Miranda Brown teaches the history of Chinese science and food in the Department of Asian Languages and Cultures at the University of Michigan. Fascinated with recipes of all kinds, she is the author of the Art of Medicine in Early China (2015) and with Yang Yong, “The Wuwei Medical Manuscripts” (2017). She is currently writing a book about the premodern history of dairy in China.

[1] Zhu Xi  朱熹, Zhuzi wenji 朱子文集 (Taipei: Defu wenjiao jijinhui, 2000), 3/110.

[2] Yang, Lian 楊鐮 (chief editor), Quan Yuan shi 全元詩 (Beijing: Zhonghua shuju, 2013), 109.

[3] For a translation of the whole recipe, see Miranda Brown, “Mr. Song’s Cheeses, South China, 1368-1644.” Gastronomica: The Journal of Critical Food Studies (Forthcoming).