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! 

Fueling Beer Breweries in Early Modern London

By William M. Cavert

Detail from the panorama of London by Claes Visscher, 1616. Image courtesy of Wikipedia.
Detail from the panorama of London by Claes Visscher (1616). Image courtesy of Wikipedia.

The shop down the road that sells alcoholic drinks offers such a variety of beers and ales that while shopping I sometimes imagine myself newly arrived from a communist planned economy into some bewilderingly choice-laden consumer paradise. Beer made in ever-so-small batches by Belgian monks, or by siblings in post-industrial Chicago, or wacky young guys working out of a garage in rural Oregon – all compete to position themselves as small-scale and artisanal, sharing nothing with the huge conglomerates that offer cheap prices but little taste. Such producers, as well as the growing numbers of home brewers, suggest that drinkers increasingly value the idea that beer should be a carefully-crafted product, something that connects us to a bygone (and yet recoverable) age of natural foods and careful cooking. As much as I applaud this shift in taste and values, as a historian I smile at the association between beer brewing and simpler modes of making food and drink.

This is because four hundred years ago in England the beer brewers of London operated businesses that helped inaugurate a modern world of environmentally-damaging industrial production. London, already during the reign of Elizabeth I and the career of Shakespeare, burned huge amounts of polluting mineral coal, and no one burned more of it than brewers. Hell, according to 17th-century English authors, was like the smoke emitted from a brewhouse chimney.[1]

But exactly how much Newcastle coal would be required to brew varied enormously, according to factors including the brewer’s preferred recipe and method, the kind of drink being prepared, and, in all likelihood, the brewer’s skill in conserving expensive fuel. One 18th-century expert on brewing, Michael Combrune, explained that brewers disagreed regarding how long to boil the wort, with preferences ranging from 5 minutes to 2 hours, concluding that experience and careful observation were the best guides. Once the hops were added, a further boil of 2-3 times the first was necessary. In general, he found, 6-7 hours of boiling was typical, but the entire discussion seems to be as much prescriptive and descriptive, a guide to what brewers ought to do.[2]

Jacob Adriaensz Matham, "View of the De Drie Leliën Brewery at Haarlem and of Velserend Manor, Owned by Johan Claesz van Loo" (1627), Frans Hals Museum, Haarlem.
Jacob Adriaensz Matham, “View of the De Drie Leliën Brewery at Haarlem and of Velserend Manor, Owned by Johan Claesz van Loo” (1627).  Image courtesy of the Frans Hals Museum, Haarlem.

Given this variety, it is no wonder that different brewers required different inputs of energy. The detailed records of the brewery within Westminster College, part of the complex surrounding Westminster Abbey, shows that in the decades around 1600 they were able to brew about 30 barrels of beer per ton of coal.[3] But in 1592 when the Brewers Company explained to the crown how much grain and fuel they required, their numbers suggest a ratio of about 3 times as much.[4] In the mid-18th century the brewhouse for Corpus Christi College in Cambridge made only about 25 barrels per ton, while at the end of the century the huge commercial brewhouse of Truman and Hanbury in London made almost 80.[5] Economies of scale must have mattered a great deal here; Truman’s produced more than 1000 times more beer than Corpus, and spent around £2000 per year on 1400 tons of coal during the 1790s. A business like that would have had both the experience and a powerful motivation to economize on fuel consumption. But even 200 years earlier some London brewers used around 500 tons per year, or 1-2 cubic meters of coal burned in a day’s brewing. Brewing, already in the 16th century, was undertaken by ambitious business people who employed dozens of workers and used a great deal of energy.

[1] This is explored in my new book, The Smoke of London: Energy and Environment in the Early Modern City (Cambridge: Cambridge University Press, 2016). For detailed calculations on industrial burning, see also William M. Cavert, “Industrial Fuel Consumption in Early Modern London” Urban History (2016), available here on FirstView.

[2] Michael Combrune, The Theory and Practice of Brewing (London, 1762), 186-88.

[3] Westminster Abbey Muniments 33,906-33,063, Abbey Stewards’ Accounts.

[4] Guildhall Library MS 5445/9.

[5] Corpus Christi College Cambridge Archives CCCC/O2/2/71; London Metropolitan Archives B/THB/B/150-1.

*****

William M. Cavert teaches early modern English, environmental, and world history at the University of St. Thomas in St. Paul, MN. He is the author of The Smoke of London: Energy and Environment in the Early Modern City (Cambridge University Press, 2016). Besides urban and environmental history, he has recently turned his attention toward England during the Little Ice Age.