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Around the Table Podcast: Archaeology of Food with Crystal Dozier

By Sarah Peters Kernan

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In this episode, Sarah Kernan speaks with Crystal Dozier, Associate Professor and anthropological archaeologist at Wichita State University in Wichita, Kansas. She is Chair for the Department of Anthropology, Director of Wichita State’s Archaeology of Food Laboratory, and City Archaeologist for the city of Wichita. Crystal describes researching food and foodways using archaeological approaches, including experimental archaeology. Follow the Archaeology of Food Laboratory on Instagram and Facebook.

Music

Frédéric Chopin, Etude Op. 10, no. 5 in G flat major

Provided by Musopen.org through Creative Commons Public Domain Mark 1.0

Mentioned in the Show

Wichita State University’s Archaeology of Food Laboratory

Grape Wine Biomarkers on Pottery Sherds

Recreating Pumpkin Leather

Recreating 16th Century Wine

Making Mead

Riley Muncher (Alumnus, Wichita State University’s Archaeology of Food Laboratory)

Transcript

Sarah Kernan 00:08

This is Around the Table, a podcast from the Recipes Project. I’m your host, Sarah Kernan. Together, we will learn about exciting scholars, professionals, projects, resources, and collections focused on historical recipes.

Welcome to Season 2, dedicated to “making.” In each episode this season, we will feature interviews with guests who describe what making means to them. For some, it is recreating a historic recipe as closely as possible. For others, it is creating something new in a modern setting. However imperfect the process or the outcome, making historical recipes offers a powerful methodology for connecting with and understanding the past in a direct and tangible way.

Today I’m speaking to Dr. Crystal Dozier, Associate Professor and Anthropological Archaeologist at Wichita State University in Wichita, Kansas. She is the Chair of the Department of Anthropology, Director of Wichita State’s Archaeology of Food Laboratory, and City Archaeologist for the City of Wichita. I am excited to speak to her today about her expertise in researching food and foodways using archaeological approaches, including experimental archaeology. Crystal, thank you so much for joining me today.

Crystal Dozier 01:36

I’m delighted to be here.

Sarah Kernan 01:38

So, as I just mentioned, one of your areas of expertise is using archaeological approaches to studying food and foodways. Could you tell us a bit more about what those approaches are and what that can reveal about food and foodways centuries or even millennia ago?

Crystal Dozier 01:56

Of course. So, in your expertise of food history, you’re focused on the written word related to humans’ relationship with food. And archaeology is the companion science to history in this way, in that we’re telling a historical story, but we do not have always the written documentation to accompany it.

So, the archaeological record is a wealth of information that isn’t written down, but rather embodied in artifacts. So, our ability to tell the history of food in archaeology is going to the remnants of cooking practices themselves. To be explicit, this is looking at animal bones. This is the burned crust on the outside of bowls that are thousands of years old. This is looking at micro botanical remains that have been carbonized and preserved for thousands of years even. So, this is a companion to the written word in our understanding of food history by looking at what was actually practiced and what physically remains from those ancient techniques.

So, I like to think of the archaeology side of it as giving us this extra window into humans’ relationship in food that is actually far deeper and far wider than what the historical narrative can tell us. The historical narrative is, of course, relegated to those manuscripts that survive, written for people who could read them, which is a minority of humans across time and space.

So archaeology gives us these insights into all of these practices that we don’t have a written record for, or when we’re lucky enough to have a written record for, usually that’s biased or partial, and archaeology can widen this view of what was actually done in the past.

Sarah Kernan 04:04

I absolutely love the way that you phrase that, that archaeology and this history are companions in creating this narrative. And that’s an excellent segue into my next question. A lot of scholars who deal primarily with this written evidence have simply relied on the work of archaeologists to supplement or support their findings. But your research and publications really show that archaeology often reveals things that simply aren’t present in other evidence or even brings to light things when there isn’t any evidence at all in a written record. So could you talk about some more examples of your work that really highlight the value of archaeological methods in revealing previously hidden or unconsidered moments in a culture’s relationship with food?

Crystal Dozier 04:57

Yeah, I think there’s lots of different ways to attack this question. I usually, as an archaeologist, I usually actually start with the written word. So, we rely a lot on the historical narrative and ethnographies that are written. But sometimes you have to realize that those are partial or incomplete. And so I have a couple of examples I can think of, one from my work and one in archaeology more general.

To come from my work, I had done a study as part of my dissertation looking at a Native American community right before Spanish colonization in central Texas. And archaeologists called this the Toyah phase, somewhere around 1350 AD to just, you know, the colonial moment, 1600, 1650.

And what we know about this group of people is that they were non-agricultural, so they’re mobile hunters and gatherers. There’s lots of bison bones at the sites. There’s usually lots of stone tools, but one of the unique things that is found at these kind of sites is pottery.

And for non-agricultural groups that are mobile, it’s a huge question of why you would put in the time and the effort to make pottery you’re doing the same life ways that you’ve done for thousands of years, you’ve never needed pottery before. You’ve got to lug it around. It’s heavy. It’s fragile. So you have all these questions about why would you start developing a ceramic tradition? And this is a group that there is no direct written history for. We have archaeological evidence, but there was no observation by colonialists into this tradition by the time that we have a historical record in North America.

So my dissertation asked the question of why would you put so much effort into making pottery for this foraging group? And one of the things that I noticed about the kinds of sites that we see for this group of folks is that quite a number of them showed evidence of feasting, of throwing really large parties that were probably inter-ethnic.

Crystal Dozier 07:12

And the reason why I say this is that we find earth ovens, which are a form of cooking technology all over the world in which people put rocks into fire, and then use the heat in the rocks to cook other foods. Usually it’s, you dig a hole, you set a fire, you put the rocks in the hole, the rocks absorb the heat of the fire.

You let the fire burn down, but the rocks are still hot. Cover it with green material, put your food in there, cover it all tightly wrapped. You cover it back up with dirt, and it’s kind of like a crock pot. It maintains the heat and will cook it for a long time without direct fire, so it’s very safe. And looking at the earth ovens at these sites are ginormous.

They are, I have to use metric, it’s 10 meters by 10 meters. That’s 30 feet by 30 feet. This is, you know, you can lie down several people inside of this crock pot, which implies that you’re either cooking something very, very large, or you’re feeding a lot of people, or both. And so these sites that have pottery for this non-agricultural community also includes pottery from the surrounding regions.

So, they’re in central Texas, but they’re pulling ceramics from east Texas and from west Texas. And so, I looked at the residue inside the pottery at some of these sites as part of my dissertation, with the idea that they’re probably making something important in them. And I had a bunch of different hypotheses about what kind of things they could be cooking. And one of the things I chose to explore is whether or not they were making fermented alcoholic beverages, because that’s what people do.

Crystal Dozier 09:04

When you throw a big party, a common feature internationally throughout human history is that you provide a beverage to your guests. And so I decided to include the ability to look for some biomarkers associated with grape wine, tartaric and succinic acids.

And to my delight and surprise, we did find this evidence of tartaric and succinic acids in this pottery sherd that predates Spanish expedition into North America. None of the colonial powers in North America reported grape wine as an indigenous product. But North America has a huge variety of “wild grapes” that colonial narratives emphasized how bountiful and available they were, which is probably because they were in the leftover stands that were being cultivated by Indigenous people prior to colonization.

And so this research helps open up the door to say, hey, even though Europeans didn’t see this, and I do think part of this is because the European mythos around fermentation is so strong, particularly wine. So that the idea that you have Indigenous folks producing the same things and using the same technology was previously unconsidered. And I hope this research opens that door to say, hey, even though the Spanish, the French, didn’t see it, doesn’t mean that this wasn’t being practiced. Because human beings love a good drink.

Sarah Kernan 10:53

Absolutely.

Crystal Dozier 10:56

And there’s tons of it. So that’s one example from my research of things that hadn’t been considered before, that was a hidden foodways. And the reason why it’s hidden, I think, you know, may be really multilayered. But archaeology in general, I think, provides these alternative narratives to challenge both the historical understanding and really empower the way we think about humans’ relationship with food.

And this is by clarifying the origin of various foodstuffs. You know, where do these products come from? And also giving, I think, a lot of respect to the people actually doing the cooking, the chefs, and the women, and domestic labor that’s actually providing these meals for their families and their communities.

Sarah Kernan 11:45

I love that description. That’s such a great example that you have there. On a kind of related note, you’ve mentioned some elements of this as we’ve been talking so far. But could you talk more about how using a methodology like experimental archaeology might differ depending on the cultural context that you’re working in? For example, you’ve researched some very different topics and cultures. You have researched pumpkin mats made by Indigenous groups in the North American Great Plains. And you’ve worked on recreating 16th century French wine following a recipe in Charles Estienne’s L’agriculture et maison rustique. And these are really different places and times and types of supporting evidence, other evidence to draw upon to supplement your work and research and narrative. How do you think about tackling such different projects and what type of evidence you can draw on that might be available to support an experimental approach?

Crystal Dozier 12:50

Sure. So my work in experimental archaeology is mostly to understand how do we know from the archaeological record what people were cooking and eating. So in order to do that we need to actually make things we think people were eating and then see how it decomposes, see how it is formulated, and what components of it may persist in the archaeological record, you know, for thousands of years.

And for these kind of studies we have to start with what we know about these food products. So that can either come from the historical record, which is either through recipes, written down, which are fairly constrained, or it has to come from ethnographies, which are third-party observations of this foodstuff. If you’re very, very lucky, another resource that we can use is oral traditions of people who have continued those foodway practices. All of these sources come with the same kind of recognition that they are a product of a time and a place and therefore are not a full understanding of a particular practice.

For example, I don’t think everyone in the sixteenth century was making wine in this one particular recipe that we found. Or for the pumpkin leather mats, which is a form of fruit leather made with pumpkin, we were able to find two different records of ethnographies, of observations, of watching it being made, and they follow different techniques.

Because the goal of these studies is to figure out what is left in the archaeological record when the food is complete, that means we also need to take account what are the scientific processes that we know are happening in order to record it. These experiments do look and feel very scientific. We are measuring everything, everything from how much time it takes to how much water we put in, you know, to the actual looking at these things underneath the microscope, which is my main focus. Is, from this food, what is left on the crumbs of the piece of pottery that we’re looking for, the microbotanical crumbs, so to say.

Crystal Dozier 15:17

So, we have to be very exacting with our methodologies. But the process of it is remarkably similar, even though we are looking from very different traditions and time periods, in that you start with what do we know about this practice? What do we don’t know? What is likely to survive in the archaeological record? How can we trace that through this experiment? And very often we find also through the practice of making these past foodways, all sorts of tactical knowledge you would never know without physically trying to do it yourself.

You know, how would you know that this particular food gets very sticky at this stage, or that it makes a particular sound? And that sound is probably rather than, you know, what we’re doing, the temperature checks and the pH levels, maybe it was it was probably that sound or that texture that led ancient cooks to know, oh, this is done. So in that way, it is very scientific.

But I also really appreciate the very humanistic nature that recreation of these foods gives you is that, oh, this is messy and cooking is messy, and why did no one ever tell me that you can dry pumpkin and then rehydrate it to use all year round?

Sarah Kernan 16:38

You’ve worked on such a variety of really interesting projects. Do you have any favorites or is there anything you’re really excited to research soon?

Crystal Dozier 16:48

Yeah. I’ll tell you maybe the highlights of the experimental archaeology is when the food turns out really good. There’s also when the food does not turn out really good. So, my most “successful” experiment, in that it turned out delicious, is probably, I made mead, honey wine. And the goal of that experiment was to figure out if the pollen in the honey survived the fermentation process. Because pollen survives for a long period of time, we know that people often add honey to all sorts of fermented beverages. And so it was a very straightforward experiment of, does that pollen, does that remain through the fermentation? And that was probably my most delicious experiment to date.

The pumpkin mat also is a very delicious experiment. So, in that, which I kind of referenced, is dried pumpkin leather, like fruit leather, that is woven into a mat, like a, think like a table mat, but not that you would put stuff on, just for storage. And that is an incredible piece of technology. That we did the experiment three years ago and it’s still hanging in my lab. It is completely still edible. And every six months, we like take out a pair of scissors and cut off a piece and dunk it in hot water and be like, is it done? Do we need to take it down? Nope, this is still pumpkin-y.

Sarah Kernan 18:32

Wow.

Crystal Dozier 18:33

So that’s the really exciting, when you’re like, wow, this really works, and it’s delicious, and it continues. Every once in a while though, you realize how much we don’t know from ancient cooks and that they knew ways to make things delicious that were not written down and we do not have access to.

So recently, one of my graduate students completed an experiment looking at mesquite bean pods. So you probably know mesquite, the little bushy tree people use its wood a lot for smoking, but the beans themselves you can grind into flour. You can make all sorts of things with that. You can make bread, you can make cakes. We were particularly interested in making beer. In South America it’s very common, it’s called algarroba. And we wanted to recreate this knowing that in North America people were probably doing it as well. And I must say, missing a written record certainly missed something for us, because the experiment was successful in that we got really great data and being able to understand if or when people might have been making this in the past, based on starch residue. But it kind of tasted like dirt.

Sarah Kernan 19:50

Oh. I’m sorry that one didn’t work out.

Crystal Dozier 19:53

That one, I mean, it fermented, it was two and a half, almost 3 percent alcohol by volume. So, a light sessionable beer, but it was pretty acidic to modern tastes. So it’s one of those things of like, okay, we’ll be able to tell this, but we need more research into what ancient people were doing because they probably knew better than we do how to make this actually delicious.

Sarah Kernan 20:19

Wow. Well, I guess you might have to have another graduate student down the line work on that one again.

Crystal Dozier 20:23

Exactly.

Sarah Kernan 20:26

If we could turn a little bit toward teaching and public engagement. Food is such an incredible way to draw in people, get them interested in all kinds of topics and fields of study that maybe they normally wouldn’t be all that engaged with. And your institution, Wichita State University, has a really incredible resource, the Archaeology of Food Laboratory. Could you talk a bit about how the lab functions and how it works with and engages students of all levels and ages, and how the lab interacts with the public and non-academics?

Crystal Dozier 21:07

Sure. So the Archaeology of Food Lab is something that I established shortly after arriving at Wichita State as a way to not only formalize a lot of these research questions that I’ve had in the basis of my research, but also explicitly to be the avenue to support not only students, but the public at large. And so the way that the lab functions is really in two different components.

The first of which is that the lab actually serves as a contract archaeology research lab. In that I take research contracts from mostly private archaeological firms with very particular questions about the foodways that they’re researching. Most of these firms work in what’s called cultural resource management, which is a compliance-based field that ensures that when development is happening, that roads, airports, anything with federal funding isn’t destroying the archaeological record as part of that development. And as those firms ensure the safety of our historical record, they encounter things that they don’t know what to do with and that very few people have expertise in.

And so my lab actually accepts samples from all over North America. And we perform the residue analysis for different areas, looking for those residues of what was being cooked in the past. We’re one of the very few labs that is able to take these as contract samples. Otherwise, you have to usually have like a personal relationship with an academic, which is complicated with university systems.

Crystal Dozier 22:56

The benefit of doing this is not only that we get to know more about the archaeological record, but I employ students to work with me on these projects. So, students, we have undergraduates and Master’s students who work, are employed in the lab, who are paid to do this research. And this is a companion to the kind of work that they’re doing as part of their educational journey. Right. So they’re learning it in the classroom and do a lot of independent studies.

All of my Master’s students have an independent thesis or research project that may or may not, you know, intersect here. But this allows us to support their work better and aid our understanding of the history. In turn, this allows the lab to be stocked for those student projects. And so almost all of these experiments that I’ve spoken about have included students. So, the pumpkin man experiment was the work of an entire class, that we took it on as a class project. I mentioned Riley Muncher is the Master’s student who worked on the Mesquite bean pod beer. So, this affords the lab the ability to do these experiments on the academic side as well. And this in turn is something that we want to ensure is available to the public.

We do a fair amount of events with our more public facing parts of the university. This is everything from public lectures. I was invited down last year, down to the Wichita and Affiliated Tribes, who is the ancestral population to a lot of the archaeological work I’m doing here in Kansas now. And they asked me to speak about what are the foodways of the Wichita and the archaeological record before the modern moment. And so I think those are really important conversations to have about what are traditional food ways, what are the forgotten food products that have really complex interactions with health and well-being.

And so, this is something I do in the classroom, but also to the public, whether it’s school groups coming to visit, or working with our art museum on campus about how do artists interact with food and what do we know about the history of it. I like to support as much of this public facing as possible and do it through avenues like this podcast and open access publishing. We talk about how hard it is in the ivory tower to get our research out there. And so whenever it’s possible, I try to make sure that our research is available freely to the public, like the pumpkin leather mat article is open online for anyone to read anywhere all over the world.

Sarah Kernan 25:54

I love how all of this feeds into itself. And you’re really supporting, through this lab, all these different really important groups and constituencies, and it’s all serving this greater purpose of both researching and garnering interest from students and the public, as well as other academics. I think that’s just so important and really great that there’s this locus on your campus for that sort of activity.

I have a final question. Let’s say someone is listening to this podcast right now and they’re thinking, oh my goodness, I would absolutely love to use all these different archaeological methods to learn more about foods in the past, but I have no idea where to start. What do you recommend, whether they’re an undergraduate student who’s maybe looking for a major, or they’re an interpreter at a historic site, or a scholar at an institution who is looking to incorporate archaeology into their bag of research tricks? What would you recommend?

Crystal Dozier 27:04

Right. So, I’ll start this with a piece of advice I love to start when talking with the general public. And it’s that our relationship with food as human beings has so dramatically changed in the last 20 years, the last 50 years, the last 100 years, the last 1,000 years. So, one technique or avenue or trick that I really enjoy is when you are sitting down to a meal or if you’re in the grocery store, try to identify or look up, just real quickly, you can just Google it, where does that food come from? Where is its origins? And I think a lot of folks don’t realize the complex histories of so many of these food products.

You know, we think of tomatoes as an essential part of pasta sauce in Italian cuisine. But tomatoes come from Mesoamerica and were considered very questionable to European tastes in the early colonial period. And not only looking at where is it, where is the origin of this food, but also what did it look like prior to domestication? Over 90% of the food we eat today has been fully domesticated and managed under human horticultural and agricultural practices.

Again, a quick Google will show you what is the archaeological record of what did this food start as? And it’s absolutely mind boggling. Look up bananas. Wild. Humans did things to these foods that has absolutely changed the landscape of our globe. And I think if you start there, of what did this food actually look like and how have humans transformed it? And you know, you can then apply that if you’re working in a particular context.

What does this narrative actually look like? What would have meant to do the dishes in this society? How would you have cleaned them? Something as simple as that. It’s not going in the dishwasher. Are you using a brush? What is the brush made out of? This kind of exploration and imagination, I think, is really crucial to the archaeological process. You really have to push yourself into what are the boundaries of what we know about the food. And there’s always more to know.

Sarah Kernan 29:34

Crystal, thank you so much for joining me today and for talking a bit about the archaeology of food.

Crystal Dozier 29:41

Of course, anytime.

Sarah Kernan 29:44

Thanks to everyone for listening today. Please remember to subscribe to this podcast so you never miss an episode. I’ll see you again next time on Around the Table.

Boiling Milk: Experimenting with Boerhaave’s Little Furnace, Part III

By Ruben Verwaal and Marieke Hendriksen

Fig. 1. Ruben keeps an eye on the temperature.
Fig. 1. Ruben keeps an eye on the temperature.

It has been exactly 350 years since Herman Boerhaave’s birthday. What better way to honour the renowned professor than to redo some of his old experiments? 

On Monday 31st of December, in the year 1668, Herman was born. And already as a kid, he and his brother James probed the curiosities of nature: plants, minerals, liquids and bodily fluids. As Herman recalled some 30 years later, “how many whole days and nights we have spent successively together in the chemical examination of natural bodies” [1]. It must have been around this time that Herman invented his little furnace.

“I’ll put an alarm to take the milk out of the freezer,” Marieke texted Ruben the week before New Years’. Between all the Christmas dinners, the 31st was the only day still free to meet up over the holiday. Weeks before we had bought Irish turf online and collected raw milk from a farm near Delft, as well as from a breastfeeding friend . Having finally found the time, we gathered their materials together and started experimenting.

Why Milk?

As a physician, Boerhaave was fascinated with the human body. How does it work? What is it made of? Boerhaave soon realised that a newborn solely grows on breastmilk. Mothers eat their food and digest it with juices from their intestines; after circulating in their bodies, the fluid concocts into chyle and develops into the maternal sustenance in their breasts. Not only human babies, Boerhaave reasoned, but all mammals are nourished by milk and can grow solely on it. “Milk, therefore, appeared to be the first thing to be examined.” [2]

Making Curd

Fig. 2. 4PM: Raw milk heated with vinegar gives you cheese - well, sort of.
Fig. 2. 4PM: Raw milk heated with vinegar gives you cheese – well, sort of.

We set out to replicate the first experiment, titled “fresh cow’s milk coagulates with acids, even in a boiling heat.” We lit the turf in the fireplace. Once it was hot, glowing, and smelling, Marieke put some in an earthenware bowl and placed it in our wooden furnace to let it heat up. Meanwhile Ruben added vinegar to fresh milk in a glass vessel. As the fluid was gradually heating up in our furnace, parts of the mixture were slowly coagulating into curd.

We were basically imitating the cheese-making proces – a more than common practice in the early modern Dutch Republic. Boerhaave, however, assigned physiological significance to this process. For the cheese could be hardened and burned, smelling like bone – proving that even the hardest parts of a baby’s body could have its origin in milk. “This is a strange change of so fluid a matter as milk, but is, perhaps, the origin of all the solids in the body.” [3]

Red Milk

The second experiment was to show how “recent cow’s milk coagulates, turns yellow, and red, by boiling over the fire with fixed alcali.” We basically repeated the previous steps, but instead of using vinegar we added ammonia. Slowly but surely, the white fluid indeed turned yellow, then a dark orange – and was about to turn red. Here we had to stop, unfortunately, because the turf was cooling down, and it was getting dark outside.

Yet via this relatively simple process, Boerhaave confirmed a common illness: milk fever. The milk from mothers suffering from fever “becomes yellow, saline, thin and sanious.” [4] It also clarified why Dutch cows gave yellow milk during the 1714 outbreak of cow’s fever.

Fig. 3. 6PM: Raw breast milk heated with ammonia: 'bloody' milk?
Fig. 3. 6PM: Raw breast milk heated with ammonia: ‘bloody’ milk?

So What Have we Learned?

First, turf smells! We can only surmise that our early modern colleagues were simply oblivious to the smell due to its omnipresence. Second, our apparatus passed the test. Boerhaave’s little furnace successfully kept the heat inside at an evenly distributed yet high temperature (around 60℃). This is an important feat, especially when working with milk. Anyone who has ever boiled milk knows how easily it becomes a big mess when you don’t pay attention for just two seconds. Yet we were able to have 15-minute glühwein and oliebollen breaks without any problem. 

Third, our experiments have shown us how relatively easily some of Boerhaave’s experiments can be replicated – as opposed to some of his contemporaries who made secret potions or applied intricate and dangerous procedures with metals and minerals. Historical reproduction, reconstruction, and re-enactment are methodologically complex and potentially problematic because of the impossibility of repeating history and reliving the experiences of historical actors. Yet our experiments do enhance our understanding of the past; they make our historical understanding more holistic, less linear and text-based. [5] For example, these experiments help us to understand why Boerhaave was such a popular teacher; with the help of a small oven based on his design, students could learn by doing. 

Fourth, with more time and patience we could have gained better results. This is the case with everything, of course. Yet some of Boerhaave’s experiments with milk – for example the milk turning sour by digestion (i.e. at 37℃) – is described as taking twelve days! Lastly, replicating early modern experiments is fun. We won’t deny that working on your object of study outside the library is refreshing. The photos and videos of the process have a public appeal too. We hope you enjoyed it.

 

 

[1] ‘Dedication’ in Herman Boerhaave, Elements of Chemistry (London, 1735), A3r.

[2] Herman Boerhaave, A New Method of Chemistry (London, 1741), 2, 185.

[3] Ibid., 187–188.

[4] Ibid., 188–189.

[5] Pamela H. Smith and Tonny Beentjes, “Nature and Art: Making and Knowing: Reconstructing Sixteenth-Century Life-Casting Technniques,” Renaissance Quarterly 63 (2010): 128–79. Marieke M.A. Hendriksen, Elegant Anatomy. The Eighteenth-Century Leiden Anatomical Collections (Leiden & Boston: Brill, 2015), Chapter 1. Donna Bilak et al., “The Making and Knowing Project: Reflections, Methods, and New Directions,” West 86th 23, no. 1 (2016): 35–55. Hjalmar Fors, Lawrence M. Principe, and H. Otto Sibum, “From the Library to the Laboratory and Back Again : Experiment as a Tool for the History of Science,” Ambix 63, no. 2 (2016): 85–97.

A Cool Oven: Boerhaave’s Little Furnace, part II

By Ruben Verwaal and Marieke Hendriksen

Ruben Verwaal is curator of the historical collections at Erasmus Medical Centre, Rotterdam, and at the Museum for Communication in The Hague. He obtained his PhD in June 2018 with a thesis on the role of bodily fluids in eighteenth-century chemistry. Marieke Hendriksen is a researcher on the Artechne Project and PI at the Art DATIS Project at Utrecht University and a long-time contributor to The Recipes Project. She specializes in the material culture of science and art in the long eighteenth century. Ruben and Marieke share an obsession with an eighteenth-century object that has since disappeared: a small chemical furnace. In a previous post, they wrote about reconstructing Boerhaave’s little furnace. Now they have two…

The newly build oven, August 2018

In August of this year, we wrote about our first attempt to recreate Boerhaave’s little furnace from old coal stoves. Meanwhile, Marieke’s dad, André, who is a skilled carpenter, was building a furnace from scratch, using Boerhaave’s description and a nineteenth-century example of a Boerhaave furnace in the collection of Museum Gouda as his guidelines. This resulted in a sturdy furnace of solid dried oak, much larger than the furnace we created from coal stoves.

The interesting thing about Boerhaave’s furnace is that many of the experiments that he described in his chemistry book, the Elementa Chemiae, for which the furnace can be used, required a very moderate degree of heat – one could say a cool rather than a hot oven. Two examples we mentioned previously were the distillation of rosemary, and the hatching of eggs, which Boerhaave said he believed his furnace could be used for too. The kind of egg is not specified, but for chicken eggs, the ideal temperature for hatching is 37,6 Celsius. Could we attain that temperature with our furnaces? 

Boerhaave advised to use glowing coals or Dutch turf as fuel, with which a constant and moderate heat should be achieved that could be kept up to 24 hours. As turf is no longer won in the Netherlands, we started with some ordinary barbeque coals – and indeed managed to establish a fairly constant heat of around 30 Celsius in the large oven for an hour or so. But coals did not hatch any chicks.

Coals: a stable 30 Celsius

Suspecting that turf may give better results, we set out to buy turf, which is still won in regions in Germany and Ireland. It turned out to be surprisingly difficult to buy in the Netherlands though. Eventually we managed to purchase a box of Irish turf through the American website of the online retailer we love to hate – but it took eight weeks (!) to arrive.  Though our cool oven still hasn’t incubated a chicken, the first results look promising.

Irish peat via the US
Irish peat via the US

Meanwhile, we started thinking about the experiments we’d like to recreate once we had all necessary materials. Since Ruben wrote his PhD thesis about bodily fluids, he is keen on reconstructing an experiment with milk from different mammals. Preferably, we’d compare the effects of prolonged mild heat on cow’s milk and human breast milk. Raw cow’s milk can be purchased at some farms, so Ruben cycled out to get some, while Marieke hesitantly contacted a friend who was pumping to feed her infant daughter to ask if she was willing to donate some of her leftovers to science. Note for future generations: Marieke has the coolest friends – she instantly said yes! For weeks, she gathered the left overs that her daughter did not drink in freezer bags.

Suddenly, it is December, and we have two furnaces, a box of Irish peat, and milk in two freezers. Now we ‘only’ have to make time for this reconstruction experiment… We live an hour apart and this is our pet project, so we’re desperately searching for a couple of days when we can take time of work. It turns out that the most difficult aspect of this reconstruction project is not the building of the furnaces or the sourcing of the necessary materials, but the absence of what Boerhaave obviously did have: cheap labour in the form of young assistants, who could take turns keeping the furnaces going day and night. We can only hope that once we do manage to take those days off, the Dutch winter is still as mild as it has been up till now! 

The “Gentle Heat” of Boerhaave’s Little Furnace

By Ruben Verwaal and Marieke Hendriksen

Ruben Verwaal is curator of the historical collections at Erasmus Medical Centre, Rotterdam, and at the Museum for Communication in The Hague. He obtained his PhD in June 2018 with a thesis on the role of bodily fluids in eighteenth-century chemistry. Marieke Hendriksen is a postdoctoral researcher on the Artechne Project at Utrecht University and a long-time contributor to The Recipes Project. She specializes in the material culture of science and art in the long eighteenth century. Ruben and Marieke share an obsession with an eighteenth-century object that has since disappeared: a small chemical furnace.

With the introduction of chemistry into the university curriculum in the late seventeenth century, new practical needs arose for students  such as being able to perform experiments. Would it be possible to build a chemical furnace that provides a gentle heat, yields no smoke, and is safe for students to use? Herman Boerhaave (1668–1738) believed he found the perfect solution in, what came to be called, Boerhaave’s little furnace.

Portrait of Herman Boerhaave by Cornelis Troost, c. 1730.

Boerhaave was professor of medicine, botany and chemistry at Leiden University in the early 18th century.[1] Instead of starting with the most difficult experiments with metals and minerals, he was convinced that students were better off when they learned the techniques of through simpler processes, such as distilling leaves and flowers, and fermenting bodily fluids. But most chemical laboratories were equipped with elaborate devices too complicated for freshmen students, who in the eighteenth century could be as young as fourteen. Moreover, the brick-build furnaces were designed to create high temperatures, in which small and delicate materials like rosemary leaves would burn instantly.[2] Boerhaave hence needed a device that was low-cost, user-friendly, and would provide a gentle heat.

The plan for the oven, • H. Boerhaave, Elementa Chemiae, Quae Anniversario Labore Docuit in Publicis, Privatisque Scholis, (Leiden 1732).

A small wooden oven was the answer. Boerhaave claimed he had designed this type of furnace when he himself was studying chemistry in the 1690s. He opened the chapter on instruments in his chemistry textbook with the words: “I shall begin with my simplest furnace; which I invented forty years ago, when I practiced chemistry in no large study, where there was only one little chimney, and where I required several furnaces at once.”[3]

Woman at the Virginal and stove under her feet, by Jan Miense Molenaer, 1630-1640. Rijksmuseum, Amsterdam.

This kind of device was probably inspired by ordinary foot stoves. These little stoves, also known as foot warmers, were very popular in the Dutch Republic. Coming in a wide variety of shapes (square, octagonal, cylinder), these stoves often feature in books and paintings. Filled with glowing coals or peat, women placed the little stoves under their robes or blankets to keep warm.[4] Many foot stoves were equipped with a wire bail handle for lifting and easy transportation. Such stoves were used in carriages, sleighs, at home and in church to keep one’s feet warm. This ordinary foot warmer got new applications too, namely as tea and coffee stove,   and we suspect it was the model for the ‘simplest furnace’ in the Leiden chemical laboratory.

Woman carrying a little stove, Harmen ter Borch, 1648–1677. Rijksmuseum, Amsterdam.

The gentle heat produced by Boerhaave’s small oven proved very useful in performing all kinds of chemical experiments. Take rosemary, for example, the evergreen aromatic shrub. Distilled atop a “violent fire”, it would have been turned to flame, smoke, and ashes. But when rosemary instead was distilled at “summer-heat” (approx. 85º F), the mild operation would instead reveal the most volatile, fragrant and aromatic part of the plant ordinarily exhaled in summer. The same process could be applied to Angelica, basil, and all other aromatic plants.

Students in the Leiden laboratory, in Herman Boerhaave, Institutiones et experimenta chemiae (‘Paris’, 1724). Ghent University Library.

Boerhaave, in other words, attributed the success of his device to one’s control over gentle heat. Whenever the wooden oven was filled with hot pieces of coal or Dutch turf that was no longer smoking, it established a constant and moderate heat that could be kept up to 24 hours. As such, the instrument was perfect for students to perform all kinds of heating processes and distillations. In fact, he was so excited about this apparatus, that he claimed that “I believe eggs may be hatched by it”.[5]

Was Boerhaave’s little furnace really that user-friendly and effective as he claimed it was? We checked it out by recreating Boerhaave’s stove and performing experiments with it. Check out our next blog to entry to find out whether we succeeded!

Creating an oven from two old stoves… to be continued!

References:

[1] More on Boerhaave, see Marieke Hendriksen, “Boerhaave’s Mineral Chemistry and Its Influence on Eighteenth-Century Pharmacy in the Netherlands and England”, Ambix(2018) and Ruben Verwaal, “The Nature of Blood: Debating Haematology and Blood Chemistry in the Eighteenth-Century Dutch Republic”, Early Science and Medicine(2017).

[2] Boerhaave, Elementa Chemiae (Leiden:  Isaac Severinus, 1732), vol 2, experiment 1.

[3] Ibid., vol 1.

[4] Le Francq van Berkhey,Natuurlyke historie van Holland (Amsterdam: Yntema and Tieboel, 1769–1778), vol. 3, 706-707, 1200.

[5] Boerhaave, Elementa Chemiae, vol 1.