Category Archives: Experimentation

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.

True Colors, or the Revelatory Nature of Cold

By Thijs Hagendijk

Heat is transformative, brings about change, separates substances or bring them together. Every student of chemistry knows how to enable or enhance a chemical reaction by applying energy to a system, usually in the form of heat. Early modern practitioners did not think otherwise. Fire was the transformative element and key to the production of all kinds of different materials, ranging from the philosopher’s stone to artisanal products such as glass, porcelain or pigments. Applying heat to bring about change is publicly ingrained thermodynamics, but one thing is even more obvious. Once heated, things have to cool down again.

Figure 1: Eikelenberg’s notes on the art of painting, comprising five different manuscripts. Photograph: Regionaal Archief Alkmaar.

When the request came to write a blogpost on cold and recipes, I was somewhat hesitant. Heat seems to elicit the most interesting stories and anecdotes, but interesting cases with respect to cold failed to come to mind immediately. Hence, I tried a different approach and looked at how cold featured in a collection of overtly practical notes on the preparation of paint materials collected by the Dutch polymath and painter Simon Eikelenberg (1663-1738). Intended for publication, he promised his readers an “accurate descriptions of the origin of making, preparation and general use of paint materials, oils, mix-fluids and varnishes.”[1]  It was within the confines of this manuscript that I began to discern two themes with respect to cold in practices of making.

Figure 2: Reconstruction of one of Eikelenberg’s varnish recipes. The varnish was prepared in a glazed pot, placed in a sand bath and heated on fire. Photograph: Thijs Hagendijk.

It is only when things have cooled down that the transformative work of heat can really be judged. Eikelenberg describes for instance how he experimented with minium, a red lead-based pigment, which he heated in a crucible and placed in a fire. “The more it glowed, the more the minium turned yellow near the sides of the crucible, the lowest parts alike; which, when it was cold, appeared to be nothing else but yellow massicot.” [2] Eikelenberg also describes the preparation of various varnishes. Here too, quality and properties of substances are explicitly observed after the varnishes have cooled down. “When the varnish was cold I found that it was rather thin and that it did not cover well.” [3]  Another varnish was prepared on a hot sand bath, after which Eikelenberg “filtered it through a cloth and let it cool: it appeared then as a thickish and yellowish varnish.” [4]  Pay attention to the word “then”: there is a clear order of things that speaks through Eikelenberg’s notes. Being cold is a condition that precedes testing and Eikelenberg makes that rather explicit.

Figure 3: It is hard to achieve a homogeneous mixture when preparing varnishes. A whitish sediment is developing in this varnish, which is in coherence with Eikelenberg’s notes. Photograph: Thijs Hagendijk.

Whereas heat is transformative, it is only in the absence of heat that things can be trusted to stay the same. Continuing with the varnishes, Eikelenberg was well aware that their preparation does not stop after the ingredients have been heated and combined. As long as it is still hot, the apparently homogeneous concoction can easily coagulate and fall apart. Eikelenberg wrote in his notes: “We can conclude that to prevent curdling it is necessary not to stop stirring before the mixture is cold.” [5] Indeed, each time he made varnishes, Eikelenberg made sure to keep stirring until everything was cooled down: “stirring steadily until all was cold” or “having stirred until it became cold”.[6]

Figure 4: Eikelenberg mentions that: “[w]e can conclude that to prevent curdling it is necessary not to stop stirring before the mixture is cold.” Passage marked in red. Photograph: Regionaal Archief Alkmaar.

For Eikelenberg, heat was both friend and foe and until his varnishes reached firm, cool ground, they required careful guidance and attention. Cooling down was thus as arduous a process as heating the mixture was in the first place. Yet, once cooled down, true colors are revealed – deprived from heat and stabilized by the cold.

[1] Simon Eikelenberg, “Aantekeningen betreffende schilderen,” MS 391, Collectie Aanwinsten, Regionaal Archief Alkmaar: fol. 1. “Naukeurige beschrijving van de oorsprong of making, bereiding en ’t algemeen gebruik der verfstoffen, olijen, mengvogten en vernissen.”
[2] Simon Eikelenberg, “Aantekeningen betreffende schilderen,” MS 390, Collectie Aanwinsten, Regionaal Archief Alkmaar, fol. 806. Original: “na mate dat het gloejend wierd, veranderde de menij die naast tegen de zijden van de kroes aan-zat en wierd geel, gelyk ook ’t onderdtste; ‘t welk doe ‘t kout was niet anders dan gele masticot geleek”.
[3] Eikelenberg, “Aantekeningen betreffende schilderen,” MS 390, fol. 827. Original: “Doe de vernis koud was bevond ik ze wat dun en datze niet genoeg dekte.” Translation from: A. van Schendel, “Simon Eikelenberg’s Experiments on the Preparation of Varnishes,” Studies in Conservation 3 (1958), 130.
[4] Eikelenberg, “Aantekeningen betreffende schilderen,” MS 390, fol. 802. Original: “Doe ‘t wel vermengt was, kleijnsde ik ‘t door een doek en liet het kout worden, wanneer ‘tzelve een dikagtige en geelagtige vernis vertoonde” Translation from: Schendel, “Simon Eikelenberg’s Experiments,” 128.
[5] Eikelenberg, “Aantekeningen betreffende schilderen,” MS 390, fol. 824. Original: “Hieruijt kan men afnemen dat om ’t schiften voor te komen, men niet moet op-houden met roeren voordat se kout is.” Translation from: Schendel, “Simon Eikelenberg’s Experiments,” 129.
[6] Eikelenberg, “Aantekeningen betreffende schilderen,” MS 390, fol. 827. Original: “gestadig omroerende totdat het gantschelijk koud was.” Translation from: Schendel, “Simon Eikelenberg’s Experiments,” 130. Eikelenberg, “Aantekeningen betreffende schilderen,” MS 390, fol. 832. Original: “tot koutwordens toe geroert te hebben”.


Ancient Cures for Asthma: Do They Really Work?

By Joanna Cunningham, as part of the Undergraduate Series

Find out more about ancient ideas on asthma, and whether the remedies that ancient physicians used actually work!

Asthma and Its Ancient Background

Asthma is an affliction of the lungs which numerous ancient physicians discussed in their writings. It was first mentioned in Homer’s works (Iliad, book 10) when men gasped for air in the moment of death. One of the Hippocratic authors was the ‘first physician to understand the relationship between the environment and respiratory ailments’ (Cserháti 2004, 248; Ryan 1793, 62), discussing cold air as a cause for asthma. However, his understanding is questionable, as he associated asthma with epilepsy and hunchbacks (On Airs, Waters and Places, 3). Galen referenced asthma over 70 times in his books (Jackson 2009, 23), but the extent of these ancient men’s understanding of asthma as a separate affliction is questionable; they make no distinction between different types of asthma (cardiac or bronchial). Instead, the Greek word asthma is used to describe the general symptoms of dyspnoea (Stolkind 1933, 37; Frea 2011).

Nevertheless, Caelius Aurelianus gave ‘a better description of bronchial asthma as a distinct disease’ than earlier physicians (Stolkind 1933, 37), and Aretaeus documented the earliest known description of the definition we use today; breathing difficulties after exercise. Therefore, we can see how the ancient understanding of asthma changed over time.

Ancient Remedies

Ancient medicinal techniques have been adapted throughout the centuries, informing modern medicine. Naturally, we are so caught up in the technology of modern medicine that we forget the routes of these discoveries. However, whether these original remedies work is something I was curious to discover. Therefore, I journeyed back in time to see whether myself, as a modern-day asthma sufferer, would have survived an ancient physician’s advice.

Ancient remedies for asthma mostly focused upon loosening the humours. There were the more dangerous and vile remedies, including drinking animal blood, eating rabbit fat and fox lungs, inhaling or consuming numerous herbs and plants, for example, coltsfoot, hellebore and hyssop (Dioscorides De Materia Medica 2.41, 2.30), blood-letting, cupping, and even surgery (Nutton 2004, 56)! However, there were just as many feasible remedies to try, including eating raisins, dried figs, vegetables, barley, capers, bread, and cake, alongside steaming, baths, wet compresses, and moderate helpings of wine with dinner (Jackson 2009, 16, 33; Stolkind 1933, 37; Sanders 2007, 73); certainly a contrast to the more gory options!

My Body on Modern Asthma Medication

My current asthma medication consists of a brown inhaler twice a day, and a blue inhaler when breathless.

On a weekly basis, I take part in numerous extra-curricular activities, including cheerleading and dance, which consist of practising our routine and performing full-outs (performing the routine as you would at the competition), with high energy stunts and bursts of energy throughout. Usually, I cope to a certain point, however, with vigorous exercise, I quickly become short of breath, and anxious about my breathing. So, let’s see how my body copes with the ancient remedies, alongside my inhaler…

My Plan

From my research, I devised the plan below, with the ancient remedies highlighted in red:

© Joanna Cunningham

This plan varied depending on what I could buy in the shop, what extra rehearsals I had, and how much time I had that day.

My Body Using Ancient Remedies

Day 1

Breakfast: Porridge with Nutella, tea.

Lunch: Niçoise salad.

© Joanna Cunningham

Dinner: Chicken thigh fillets, roasted vegetables, glass of red wine.

© Joanna Cunningham

Day time:

© Joanna Cunningham

Bed time: Warm flannel on chest, arm massage.

Exercise: Dance (8-9.30pm) – my heart rate increased, I was sweating, and my breathing became rapid and difficult.

Findings: My breathing was no different to usual; I became rapidly out of breath during dance. However, after only one day, I cannot discredit these ancient cures just yet…

Day 2

Breakfast: 1 toast, with avocado and scrambled egg, tea.

Lunch: Niçoise salad, honey and lemon water, piece of birthday cake.

Dinner: Chicken, roasted vegetables, glass of wine, peanut m&ms.

Snacks: Honey and lemon water, and finished the snacks from the bowl yesterday. I dislike the figs, however, as with any medicine, you take it regardless.

Day time: 10 minute steam.

Bed time: Warm flannel on chest, arm massage, lavender-scented bath.

© Joanna Cunningham

Exercise: Dance (8-9.30pm) – same as yesterday.

Findings: My breathing recovery time was speedier than usual, but I’m sure this was either psychological, or by chance.

Day 3

Breakfast: 2 toast, 2 poached eggs (I didn’t finish this), tea.

Lunch: Vegetable and barley broth.

© Joanna Cunningham

Dinner: Chicken, roasted vegetables, glass of wine.

Snacks: A mini-roll, lemon and honey water.

Day time: Sing-along to my favourite playlist.

Bed time: Wet flannel on chest.

Exercise: Cheerleading (3-5pm)/Dance (9.30-10.30pm) – I sweated, and was a little out of breath.

Findings: My breathing was difficult by the end of each routine, but my recovery time was great!

Day 4

Meals: I was very ill, so didn’t eat anything.

Day time: Arm massage, 10 minute steam.

Bed time: Bath, wet flannel on chest.

Day 5

Breakfast: Toast with scrambled eggs.

Lunch: Vegetable and barley broth.

Dinner: Salmon, barley, asparagus, broccoli, glass of wine.

© Joanna Cunningham

Snacks: Mixed nuts, raisins and figs.

Day time: Another sing-along.

Bed time: Wet flannel on chest, arm massage, 10 minute steam.

Exercise: Cheerleading/Dance Showcase (6-8pm) – 3 full-outs of each routine.

Findings: After each run through, I felt out of breath, however, I recovered quickly.

What My Findings Have Shown Me…

My findings have shown me that these ancient techniques really do work, as my recovery time seemed to improve throughout the week. However, could this simply be a trick of the mind? Or could it just be that a relatively healthy life-style, ensuring to take care of one’s body, works wonders? In reality, only by the 16th century were doctors able to identify and diagnose asthma, and only sometimes able to treat it successfully (Hicks 2006, 30). I think I’ll stick to my inhaler for the foreseeable future, but I see no harm in ensuring to maintain a healthy lifestyle, minus the ancient addition of copious glasses of wine!

My name is Joanna Cunningham, I am 21, and I am currently in my final year at Cardiff University, studying Ancient and Medieval History. I am a cat lover and sushi fanatic, and have always been a keen writer. After writing my ancient asthma cures blog post for my second year Greek and Roman medicine module, I was totally inspired. Since this assignment, I have started up my own blog focusing on lifestyle, fashion, beauty, food, productivity, and travel (you can find  it following this link), and I am now looking to start a career in content writing, copywriting, and journalism, as this is what I am truly passionate about.

Alchemical Recipes in the AlchemEast Project

By Matteo Martelli

What makes a recipe alchemical? Its inclusion in an alchemical treatise, one might suggest. Indeed, naïve as it may sound, such a simple answer opens an interesting perspective from which to look at the ancient alchemical tradition.

The earliest alchemical writings produced in Graeco-Roman Egypt (1st-2nd c. AD) include recipes that describe a variety of techniques for dyeing and manipulating the natural world – a spectrum of practices that goes far beyond simple attempts to produce gold out of ‘vile’ metals. Some of these techniques, ancient authors claim, were inherited from the Egyptian or Babylonian tradition; others reached Byzantium or Baghdad, often through translations of Greek texts into Syriac and Arabic.

This long-lasting tradition is as fluid as the boundaries of ancient alchemy. By mapping the specific practices and recipes detailed in each alchemical work, it will be possible to investigate changing ideas of alchemy over time as well as how these ideas responded to specific technological settings. On top of that, it will also be possible to follow the trajectories of single recipes which moved across works written in different languages or pertaining to different disciplines, such as medicine or natural philosophy.

Cinnabar (from the Monte Amiata mine, Tuscany) and metallic mercury

But let’s take an example from a set of texts that are being investigated in the framework of the ERC project AlchemEast, acronym for “Alchemy in the Making From ancient Babylonia via Graeco-Roman Egypt into the Byzantine, Syriac and Arabic traditions (1500 BCE – 1000 AD)”. Ancient natural philosophers and physicians recorded specific techniques for extracting mercury from cinnabar, its natural ore.

In his book On stones, Theophrastus, successor of Aristotle as head of the Lyceum, explained that it is possible to produce mercury by grinding cinnabar with vinegar in a copper mortar with a copper pestle.[1] The same procedure is described by Pliny the Elder, in book 32 of his Natural History, where the medical uses of minerals – mercury included! – are illustrated (NH 32.123).

Modern chemists noticed that these accounts actually described a mechano-chemical reaction between copper and cinnabar, a mercury sulfide: copper would react with sulfur, thus liberating free metallic mercury (chemically speaking, a redox reaction).[2] With the assistance of Lucia Maini and Massimo Gandolfi, two chemists of the AlchemEast team, we did replicate the technique with some adjustments. Rather than using a copper mortar – which proved to be very difficult to find in the shops that supply chemical labs today! – we decided to use a ceramic mortar where to grind pure cinnabar, acetic acid and copper powder.

Pure cinnabar, acetic acid and copper powder in a ceramic mortar

After grinding the mixture for a while, we were actually able to produce a layer of blackish powder (a mixture of metacinnabar and copper sulfide) on which a few drops of ‘dirty’ mercury were moving.

Mercury “floating” on a blackish layer of residues

The same procedure is described in ancient alchemical texts as well. The Graeco-Egyptian alchemist Zosimus of Panopolis (3rd-4th century AD) credits legendary figures, such as Maria the Jewess or Chymes, the eponymous hero of alchemy (called chymeia in Antiquity), with the use of similar technique for grinding cinnabar with vinegar in a lead or tin mortar.[3] Different metals were therefore used. In the lab, we actually tried to use tin rather than copper powder, thus obtaining a shiny mercury-tin amalgam.

Mercury-tin amalgam

We may preliminarily observe how this extraction technique was a kind of transdisciplinary know-how, shared by experts in different fields. A certain degree of variation is detectable in alchemical texts, which mention various metals. Moreover, ancient alchemists believed that mercury could be extracted from any metallic (or even mineral) body:  did this idea in some way depend on the empirical evidence they tried to conceptualize when treating cinnabar with a variety of metals?

This kind of questions are at the basis of the AlchemEast project, which explores ancient recipes from a double angle: as textual units that travelled over time and space; as invaluable windows on a wide spectrum of real practices and techniques. Textual criticism, replications, and historical investigations are critical keys to unlock ancient alchemical sources, from Babylonian tablets to Greek, Syriac and Arabic manuscripts.  This post is only a first, tentative attempt to illustrate how we applied this method, a preliminary result of our investigation, which, needless to say, is still “in the making.” We plan to continue keeping you posted in the following months.

[1] David E. Eichholz, Theophrastus, De Lapidibus, edited with Introduction, Translation and Commentary (Oxford: Clarendon Press, 1965), 81.
[2] Lazlo Takacs, “Quicksilver from Cinnabar. The First Documented Mechanochemical Reaction?” JOM. Journal of the Minerals, Metals and Materials Society, 52 (2000): 12-13.
[3] Marcelin Berthelot and Charles-Émile Ruelle, Collection des anciens alchimistes grecs (Paris: G. Steinheil, 1887-1888), vol. 2, 172. Part of Zosimus’ writings is only preserved in Syriac translation, where one finds further interesting details: cinnabar must be ground in the sun; copper filings are added to cinnabar and vinegar before grinding. The Syriac books of Zosimus will be published within the AlchemEast project.