BOOTH, Christopher. Holy alchemists, metallurgists and pharmacists

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Holy Alchemists, Metallurgists, and Pharmacists: The Material Evidence for British Monastic Chemistry* Christopher Booth Introduction Medieval monastic communities were centres of knowledge and learning in their time. This knowledge included elements of what we today would consider so-called ‘hard sciences’, and chemistry, amongst them. Outdated historiography suggested that this medieval practice, of chymistry or alchemy, was not experimental science but a spiritual tradition, or less generously, charlatanism.1 *  This article grew out of AHRC funded master’s research undertaken at Sheffield University

and I would like to thank my supervisor during that research, Dr Hugh Willmott. In addition, an early version of this article was presented at the Fourth Annual Postgraduate Monasticism Conference: ‘Monastic Sciences: Medicina, Mechanica, Philosophia’ held at the University of Leeds, 8–9 May 2015, and I would like to thank the organizers and delegates at the conference for their comments and questions on the paper, including Stephen Moorhouse, whose 1972 paper ‘Medieval Distilling Apparatus of Potter and Glass’ was the starting point for this research. 1 

For example, Butterfield, The Origins of Modern Science.

Christopher Booth ([email protected]) is a Doctoral Researcher at the University of Nottingham. Abstract: The history of alchemy has relied primarily on textual evidence with few studies of pictorial sources, and even fewer focusing on the material culture of alchemical practice. Building upon the small body of work in this area and applying it to monastic sites this paper analyses twenty-three assemblages from monastic sites in Great Britain and Northern Ireland to show that distillation, cupellation, and sublimation were all practised at British monastic sites. An attempt is made to explore the specific uses of these chemical processes at each site with alchemy, medical chemistry, and metallurgy all being indicated. It is concluded, that although explaining specific uses of chemical apparatus at any one site may be beyond the reach of current scholarship, more work is needed in this area so that monastic chemistry can be better understood through its material culture. Keywords: alchemy, chemistry, material culture, archaeology, metallurgy, pharmacy, cupellation, distillation, sublimation. The Journal of Medieval Monastic Studies, 6 (2017), 195–215     BREPOLS

PUBLISHERS 10.1484/J.JMMS.5.115442

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A more recent understanding of the relationship between alchemy and the history of chemistry, or science in general, however, has acknowledged that the medieval and early modern alchemists were among the most practically inquisitive minds of their time, saw their practice as a serious pursuit, and produced results that are not only experimentally replicable, but achieved chemical interactions that are difficult even with modern apparatus.2 In contrast to the renewed attention paid to the textual sources on alchemy, the material culture from this key period of chemical experimentation has rarely been studied in Britain, and never synthesized in the context of medieval monastic institutions. In this paper the published physical evidence of monastic chemistry from British sites is collated better to understand the aims and methods of the experimenters who may have used them. The presence of material culture suggesting some basic, and some notso-basic, forms of chemistry is long established at monasteries in the British Isles, and yet little explored. One key paper in this regard is Stephen Moorhouse’s 1972 ‘Medieval Distilling Apparatus of Pottery and Glass’ published in the journal Medieval Archaeology.3 This paper, useful as it has been, was originally published as a starting point to stimulate further interest and research into archaeological evidence for distillation, and by extension all forms of medieval chemistry. However, this original aim has not been met in the forty years since, despite there being many more sites with evidence of chemical processes published. Instead of just focusing on distillation, however, this paper takes a wider view and identifies other chemical processes in evidence through the material culture of monastic houses in the British Isles and attempts to explain the probable use of the processes so identified. Data from twenty-three published monastic sites are included here (See Table 3), and from these there is evidence for three major chemical processes: distillation, cupellation, and sublimation. These three processes will be focused upon as they are representative of high-level chemistry in medieval monastic contexts. Of the three processes, distillation is the most common. Distillation is a process by which a liquid is boiled and the resultant vapours are condensed and collected to concentrate one part of the initial liquid. It may have been practised in some form in classical Europe, China, and/or India as early as the first century ad, a date that is supported by archaeological evidence from the Indus Valley, although not from Europe.4 Knowledge of distillation in the Middle East dates 2 

Fors, Principe, and Sulbum, ‘From the Library to the Laboratory and Back Again’; Moran, Distilling Knowledge, p. 9; Principe, The Secrets of Alchemy, pp. 2, 153. 3  Moorhouse, ‘Medieval Distilling Apparatus’. 4  Anderson, ‘Instruments and Apparatus’, p. 225.

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to at least the fourth century ad when the writings of Zosimos of Panopolis, a Graeco-Egyptian alchemist, describe apparatus for distillation.5 The two most significant distillates of later centuries, mineral acids and alcohols, were likely only discovered within Western Europe in the twelfth century, as recipes for their production only became common by the thirteenth or fourteenth centuries.6 The second most common process in the material record is cupellation, in which a composite ore or man-made alloy, usually of lead and silver, is melted, the lead oxidizes and is then absorbed by the vessel or hearth and leaves behind a button of molten silver. Cupellation can be traced back as far as the Early Bronze Age when it was used to separate silver from lead ores, a use that continued through the medieval period.7 As such it may well be the oldest analytical process in chemistry. The rarest of the three identified processes is sublimation, a process which changes a solid material into its gas state without an intermediary liquid phase. This is similar to distillation, although only some solids can successfully produce sublimates, among them sulphur and mercury compounds important in alchemy. The history of this process is a little more obscure. The writings of Maria the Jewess, a possibly mythical early alchemist of Late Antiquity, mention ‘sublimatories’; however there is little else to suggest that the process was widely conducted.8 Although certain sublimates such as a corrosive mercury sublimate, were used by goldsmiths and apothecaries from at least the fifteenth century, sublimation apparatus is much more likely to suggest alchemical practice than material culture associated with distillation or cupellation.9

5 

Principe, The Secrets of Alchemy, pp. 14–15. Anderson, ‘Instruments and Apparatus’, p. 225; Forbes, A Short History of the Art of Distillation, p. 86; Multhauf, The Origins of Chemistry, pp. 204–05. 7  Rehren and Eckstein, ‘The Development of Analytical Cupellation’, p. 445. 8  Janowitz, Magic in the Roman World, p. 65. 9  Pomet, Lémery, and Pitton de Tournefort, A Complete History of Drugs Book II, p. 100. 6 

198 Christopher Booth

Site

Processes

Date

St Patrick’s, Armagh

Cupellation?

435–605 ad

Monastery at Portmahomack, Tarbat Ness Cupellation

Pictish (pre-800 ad)

Hospital of St Mary Magdalene, Partney, Lincolnshire

Distillation or Sublimation

Twelfth to thirteenth centuries

Polsoe Priory, Exeter

Distillation or Sublimation

Thirteenth century

Abbey of Strata Florida, Cwmystwyth, Wales

Cupellation

Thirteenth century

Kirkstall Abbey, Leeds

Distillation or Sublimation

Thirteenth century (?)

Jedburgh Abbey, Scottish Borders

Distillation

Thirteenth to fourteenth centuries

Salisbury Franciscan Friary

Distillation

Thirteenth to fourteenth centuries

Bayham Abbey, East Sussex

Distillation

Thirteenth to fifteenth centuries

St Frideswide’s Priory, Oxford (?)

Distillation

Fourteenth Century

St Mary’s Priory, Selborne

Distillation

Mid fifteenth century

St John’s Priory, Pontefract

Distillation

Fifteenth to sixteenth century

Hulton Abbey, Staffordshire

Distillation

Fifteenth to eighteenth century

St Leonard’s Priory, Stamford

Distillation

Early sixteenth century

Thorney Abbey, Cambridgeshire

Cupellation

c. Dissolution (1536–41)

Carmarthen Greyfriars

Cupellation

c. Dissolution (1536–41)

Thornton Abbey, North Lincolnshire

Cupellation

c. Dissolution (1536–41)

Monk Bretton Priory, South Yorkshire

Cupellation?

c. Dissolution (1536–41)

Battle Abbey, East Sussex

Distillation

Sixteenth century

The Carmelite Friary, Friary Lane, Nottingham

Distillation

Medieval

Denny Abbey, Cambridgeshire

Distillation?

Medieval to seventeenth century

Grove Priory, Bedfordshire

Distillation

Late Medieval

Byland Abbey, North Yorkshire

Sublimation

Unknown

Table 3. The twenty-three British monastic sites with published evidence of chemical processes, the processes represented at each, and the approximate date of the relevant material culture.

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The Archaeological Evidence As can be seen in Table 3 there is almost no overlap between these processes at any site, and as such the material culture can be analysed separately and in order of prevalence beginning with distillation vessels. There are several vessels that can indicate the practice of distillation at a site and, although contemporary sources depict a huge variety of still-form, they all tend to conform to the same basic structure:10 Alembic – The still head (see fig. 21 – (1)) Cucurbit – The still body (see fig. 21 – (2)) Receiver – The vessel to collect the distillate (see fig. 21 – (3))

Archaeologically the most important vessel is the alembic. This is the only vessel that can be described as diagnostic of distillation, and glass examples from the medieval period can be easily identified by the double curve of the collecting channel as can be seen in fig. 21. There are also ceramic stills in two forms known archaeologically, one of which occurs before the Dissolution of the Monasteries (see fig. 22).11 This form has no double curve due to its lack of the long, everted neck that the glass form possesses; it does however tend to survive more readily than the glass type and so can still be identified. There are also documentary references to, but no archaeological evidence from, the medieval period for stills made in lead, pewter, and copper. These may have been illegal in some places in Europe because some products from them were known to be poisonous, and additionally they would likely have been recycled before entering the archaeological record.12 Though seven extant examples of pewter still heads have been identified in museum or stately home collections in England, all are dated to the post-medieval period.13 Using this framework there are five sites where distillation is unequivocally present and the vessels are illustrated, two where it was clearly present from the report’s description but not illustrated, and a further seven where it is indicated, but not certain (see Table 4). The five illustrated sites where distillation is 10 

Moorhouse, ‘Medieval Distilling Apparatus’, p. 89. Booth, ‘The Stalled Development of the Still’, p. 422. 12  Forbes, A Short History of the Art of Distillation, p. 76; Moorhouse, ‘Medieval Distilling Apparatus’, pp. 105–06. 13  Hayward and Hayward, ‘Pewter Stills’, p. 6. 11 

200 Christopher Booth Figure 21. Typical setup of a medieval two-part still made of glass. Showing the Alembic (1), Cucurbit (2), and Receiver (3). © Catherine Downey 2016.

Figure 22. The archaeologically recognized medieval form of ceramic alembic. © Catherine Downey 2016.

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definitely present are Battle Abbey, East Sussex, where one glass cucurbit and one ceramic alembic of the medieval type were excavated,14 the Carmelite friary in Nottingham where a ceramic alembic was misidentified in the 1930s as an ‘oil carrying pot’,15 Hulton Abbey, Staffordshire, where two ceramic alembics were excavated,16 and finally St Mary’s Priory, Selborne, and St John’s Priory, Pontefract, where the largest assemblages of distillation material ever excavated in Britain were found, including six glass alembics at each site and numerous cucurbits in both glass and ceramic.17 In addition, there is one site that may belong either to St Frideswide’s Priory or Christ Church College, Oxford; the exact find spot and its chronology makes this difficult to distinguish.18 The second process, cupellation, is represented far less frequently in the archaeological record. Cupellation is carried out in two main ways, either in specific hearths built for the purpose or in bone-ash crucibles which absorb the lead and impurities from a metallic mixture.19 Either of these types of material culture is diagnostic for cupellation, as both show high lead concentrations when chemically analysed and, especially in the case of bone-ash crucibles or cupels, are only used for cupellation. The larger scale cupellation hearths or furnaces sometimes used were ashlined and bowl-shaped constructions into which both the fuel and the metal to be purified were placed. These are hard to distinguish with confidence, and it has been argued that the majority of identified examples are simple lead melting hearths and not for cupellation.20 Since the present paper is taking published information as its starting point this issue will affect some of the sites in Table 5; however, if at least some of the examples are true cupellation hearths then they appear to vary considerably in size, from less than 0.5 metres in diameter to approximately 2 metres. An experimental reconstruction with a brick base 1.4 metres tall supporting the hearth that was 1.2 metres in diameter was successfully

14 

Charleston, ‘Vessel Glass’, pp. 113–16; Streeten, ‘The Pottery’, p. 100. Parker, ‘Nottingham Pottery’, p. 86. 16  Klemperer and Boothroyd, Excavations at Hulton Abbey, p. 176. 17  Moorhouse, ‘Medieval Distilling Apparatus’, pp. 92–100. 18  Blinkhorn, ‘Pottery from Tom Quad’; Tyson, ‘Christ Church, Oxford’; Tyson, ‘Four­ teenth-Century Glass Distilling Vessels’, pp. 12–13. 19  Guirado and others, ‘Initial Experiments on Silver Refining’; Principe, The Secrets of Alchemy, p. 153. 20  Willmott, ‘Glazeniers en het vervaardigen, herstellen en hergebruiken van vensters’. 15 

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Site

Alembic

Cucurbit

St Leonard’s Priory, Stamford (Mahaney, ‘St. Leonard’s Priory’)

Glass

Glass

Battle Abbey, East Sussex (Hare, Battle Abbey)

Pottery

Glass

Bayham Abbey, East Sussex (Streeten, Bayham Abbey)

—

Pottery and Glass

Jedburgh Abbey, Scottish Borders (Cruden, ‘Scottish Medieval Pottery’)

—

Pottery

The Carmelite Friary, Friary Lane, Nottingham (Parker, ‘Nottingham Pottery’)

Pottery

—

Denny Abbey, Cambridgeshire (Charleston, ‘Excavations at Denny Abbey’)

No Alembic or Cucurbit — Pottery Receiver

Hulton Abbey, Staffordshire (Klemperer & Boothroyd, Excavations at Hulton Abbey)

Pottery

—

Salisbury Franciscan Friary (Tyson, ‘Glass Vessels’)

—

Glass

Kirkstall Abbey, Leeds (Moorhouse and Slowikowski, ‘The Pottery’)

—

Pottery

Hospital of St Mary Magdalene, Lincolnshire (Atkins & Popescu, ‘Excavations at the Hospital of St Mary Magdalen’)

—

Pottery Distilling Base

St Frideswide’s Priory, Oxford (?) (Blinkhorn, ‘Pottery from Tom Quad’; Tyson, ‘Christ Church, Oxford’; Tyson, ‘Fourteenth-Century Glass Distilling Vessels’)

Glass

Unknown

Polsoe Priory, Exeter (Allen, Medieval and Post-Medieval Finds from Exeter)

—

Pottery Distilling Base

St Mary’s Priory, Selborne (Moorhouse, ‘Medieval Distilling Apparatus’)

Glass

Pottery and Glass

St John’s Priory, Pontefract (Moorhouse, ‘Medieval Distilling Apparatus’)

Glass

Pottery and Glass

Grove Priory, Bedfordshire (Baker, La Grava)

Glass

—

Table 4. The fifteen sites with published evidence of distillation and what specific vessels have been identified.

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fired and has confirmed the viability of furnaces between these sizes.21 As all the identified examples date to a dissolution phase, however, all the hearths in the table are more likely to have been for scrap lead melting and not cupellation. Thus, I will focus on the other evidence for cupellation. Bone-ash crucibles and cupels are less common than ‘cupellation furnaces’. It should be noted, however, that bone ash was not the only material used to make cupels; crucibles of low quality; porous clays may also be cupels of the kind in use by the Romans.22 These will tend to look like crucibles unless a lead residue or litharge cake is found in association with the vessel. Furthermore, there are records of assayers in Devon using waste oak ash from tanneries; however this type of cupel was destroyed during the process so would not be archaeologically visible.23 These other materials were likely used because bone-ash cupels were expensive.24 The vast majority of known bone-ash cupels are from continental laboratory sites including Oberstockstall, Austria, where approximately sixty Site

Hearth or Vessel?

Thorney Abbey, Cambridgeshire (Thomas, ‘Evidence for the Dissolution of Thorney Abbey’)

Hearth

Carmarthen Greyfriars ( James, ‘Excavations at Carmarthen Greyfriars’)

Hearth

Thornton Abbey, North Lincolnshire (Willmott & Townend, Thornton Abbey Project 2nd Interim Report 2012)

Hearth

Monk Bretton Priory, South Yorkshire (Willmott and Bryson, ‘Changing to Suit the Times’)

Hearth

Monastery at Portmahomack, Tarbat Ness (Carver, ‘An Iona of the East’)

Vessel

St Patrick’s, Armagh (Brown and others, ‘Excavations on Cathedral Hill’)

Vessel

Abbey of Strata Florida, Wales (Hughes, The Cwmystwyth Mines)

Neither — assay of lead waste

Table 5. Sites published with possible evidence for cupellation, and the form that evidence takes.

21 

Guirado and others, ‘Initial Experiments on Silver Refining’ Oddy, ‘Assaying in Antiquity’, p. 54. 23  Nriagu, ‘Cupellation’, p. 671. 24  Martinón-Torres and Rehren, ‘Ceramic Materials in Fire Assay Practices’, p. 145. 22 

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were found.25 Cupels made of bone ash have a roughly made construction that approximates crucibles or other small open vessels. From the British Isles there are two, very early, monastic sites where cupels have been reported: the monastery at Portmahomack, Tarbat Ness, dating to before 800 ad, and St Patrick’s in Armagh which dates to c. 435–605 ad.26 Additionally there is another site where cupellation is confidently indicated despite there being no hearths or cupels evident. At the abbey of Strata Florida, an assay of the large quantities of lead waste found on the site indicated that cupellation was used to remove silver from the lead ores from a nearby mine which the abbey owned.27 The final process addressed in this paper is sublimation. Unfortunately, there are no properly published sublimation vessels identified from British monastic sites, a statement that is perhaps not surprising given that the scholarship on medieval chemistry suggests that sublimation was associated with alchemy, and may have been practised with greater secrecy than the other, more common, processes. There is, however, a published example from a secular site, Weoley Castle (Birmingham), where an aludel (the name for the top vessel in sublimation apparatus) was found with a matching distilling base type vessel.28 These vessels give a good idea of what to look for at monastic sites and perhaps explain why this vessel type is seemingly under-identified; the top vessel, when only found fragmented, is likely confused for domestic pottery as there are no diagnostic characteristics such as a collecting channel present (see fig. 23). Given this, there is one monastic site where a possible aludel has been identified, at Byland Abbey in Yorkshire, where it is said there was a ‘pot, shaped like an inverted funnel, found during clearance work […] similar to the Weoley Castle example but more constricted at the neck with an aperture in the enclosed top’.29 Unfortunately this monastic example has never been published and so the only information available is the English Heritage object record (accession number 81005110; Byland Abbey ceramic case no. 7), which describes the vessel as a conical alembic hood for distillation. However, the fact that it has a hole in the top suggests more strongly that it was an aludel for sublimation.

25 

Martinón-Torres, Rehren, and Von Osten, ‘A 16th-Century Lab in a 21st-Century Lab’. Brown and others, ‘Excavations on Cathedral Hill’, pp. 116–17; Carver, ‘An Iona of the East’, p. 3. 27  Hughes, The Cwmystwyth Mines, p. 5. 28  Linnane and others, An Archaeological Overview of Weoley Castle, p. 8; Oswald, ‘Interim Report on Excavations at Weoley Castle’, p. 81. 29  Moorhouse, ‘Medieval Distilling Apparatus’, p. 114. 26 

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Figure 23. Illustration of a typical aludel of the same form as the one excavated at Byland Abbey. © Catherine Downey 2016.

Discussion Without access to the material archive, information about the archaeological context as well as site histories are the only way to suggest a specific purpose for chemistry at any of these sites. This might include the order to which the monastery belonged, other material found in association with the distillation vessels, and published chemical residues. The first point of reference though should be the documentary record. Recent advances in interpreting the practical aspects of the notoriously cryptic alchemical texts, often previously assumed to be a purely textual rather than laboratory tradition, have shown that medieval chemical writings can be roughly divided into metallurgy, pharmacy, and transmutation (gold making).30 These distinctions are arbitrary anachronisms, however. In the medieval period, there were significant links between medicine and alchemy; indeed, alchemy itself could be medicine.31 Both alchemical and 30 

For a summary and discussion of the ‘new historiography of alchemy’, see MartinónTorres, ‘Some Recent Developments in the Historiography of Alchemy’. For evidence of the practicality of these texts see Fors, Principe, and Sulbum, ‘From the Library to the Laboratory and Back Again’, p. 87. 31  Kieckhefer, Magic in the Middle Ages, p.  138; Obrist, ‘Visualisations in Medieval Alchemy’; Redgrove, Alchemy: Ancient and Modern, p. 90.

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medical uses of alcoholic quintessence, an important product in the history of both fields, were well known from the fourteenth century when John of Rupescissa wrote about them.32 Whilst not necessarily more important than the transmutation of base metals into gold, known as chrysopoeia,33 which made use of metallurgical apparatus and techniques such as fire assay, the making of medicinal quintessence was certainly less strictly legislated.34 Complicating the picture even further is the fact that products which do not fit easily into any of those categories were also produced by monastic communities; these include essential oils, extracts, and perfumes.35 Adapting the distillation-focused work of Moorhouse’s 1972 paper we can surmise four likely explanations for the presence of chemical vessels on a monastic site. 1. The site is a manufacturing site that produced chemical vessels a. If this were the case, then there should be other evidence of ceramic and glass manufacture. 2. Th e apparatus was used in a kitchen to produce consumable products, essen­ tial oils, extracts, or perfumes (only applies to distillation) a. In this case, adherent deposits, where they survive, would show carbon, carbonaceous or organic matter. 3. The apparatus was used for alchemical experiments a. This is likely to be found at religious institutions. Textual sources, many of which were written by monks or canons such as George Ripley of Brid­ling­ton Priory, indicate monasteries and priories were sites of alchemical practice.36 b. Any adherent deposits however would not be diagnostic as alchemists could have distilled almost anything in the pursuit of their art although mercury, sulphur, and antimony are likely. 32 

DeVun, ‘Prophecy, Alchemy, and the End of Time’, pp. 3, 53. From the Greek, meaning literally ‘to make gold’, used to indicate metallic transmutation. 34  Alchemy, and specifically chrysopoeia was made illegal by Henry  IV except under letters patent granted by the Crown. For discussion of a rare example of a petition related to medicinal alchemy see Geoghegan, ‘A Licence of Henry VI to Practice Alchemy’; Pereira, ‘Mater Medicinarum’. 35  Forbes, A Short History of the Art of Distillation, p. 91. 36  Rampling, ‘The Catalogue of the Ripley Corpus’. 33 

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4. The apparatus was used in metallurgy a. If this were the case, then there would be evidence for other metallurgi­ cal work. b. Possible adherent deposits would be inorganic with a high proportion of iron or copper, possibly lead or tin. c. These are likely to be found on sites connected with mints. In the case of monastic institutions, it is possible in most cases to rule out high quantity manufacture of apparatus, but the three other explanations are all possible. It is clear that distillation was a widespread process in English monasteries, and this is not surprising as the process had uses beyond the arcane and alchemical, for example in kitchens making consumables. Most of the distillation vessels were excavated from the reredorter where it appears they were discarded when the monastery was dissolved. This suggests that there were assemblages of distillation vessels in use for the whole later life of many of these houses which again reinforces how pervasive distillation was. Distinguishing a specific explanation for the presence of distillation material at monastic sites is extremely problematic. At the abbey of St Mary at Hulton in Staffordshire, for example, there is very little analysis of the finds, find spot, or site history as it could relate to the distillation vessels. The authors believed that the material was used to produce alcohol possibly for medicinal purposes but cite no supporting evidence.37 Similarly, at the Carmelite friary in Nottingham there was almost no additional contextual information, in this case to a point where any attempted explanation would be guesswork.38 In a few cases, however, additional details from the excavation reports help suggest certain purposes for the stills. At Battle Abbey, for example, although the publication’s authors made no attempt to discuss the purpose of the distillation vessels, it can be suggested that because those vessels were found in association with a small jar containing a mercury residue, a medicinal or alchemical purpose for the material is likely, as mercury was used in both.39 Similarly, the pottery and glass distillation material possibly deriving from St Frideswide’s Priory in Oxford, was found in combination with a tentatively identified sand-bath suggesting a more careful heating of the vessels which would be necessary for systematic alchemical experimentation.40 37 

Klemperer and Boothroyd, Excavations at Hulton Abbey, pp. 150–51. Parker, ‘Nottingham Pottery’, p. 86. 39  Streeten, ‘The Pottery’, p. 125. 40  Blinkhorn, ‘Pottery from Tom Quad’. 38 

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For sites with evidence of cupellation, things are slightly simpler. The two forms of cupellation material culture are divided chronologically, with the evidence for monastic cupels only dating to before 800 ad, and the only examples of hearths with possible evidence for cupellation belong to dissolution phases. Additionally, cupellation has only one purpose: to separate precious metals from alloys or ores, especially of lead. These dissolution phase hearths are far more likely to have been simply for lead-melting rather than cupellation; the lead from the monasteries that was being recycled would undoubtedly have had any silver content removed previously, so cupellation would have been an unnecessary step. However, there are a few sites with some indicators that would require further examination to be certain. At Carmarthen Greyfriars, for example, there is evidence from the infirmary for the melting of lead and other metals in at least one pit-hearth that had an ash, possibly bone ash, lining embedded with lead residue which is characteristic of attempts to extract silver from lead.41 The fact that this process was taking place in the floor of the infirmary is a clear indication that it was being practised at the Dissolution or in the post-Dissolution period. There are two British sites with published evidence of cupels: St Patrick’s in Armagh and the monastery at Portmahomack, Tarbat Ness. The vessels, described as ‘heating trays’, from St Patrick’s were found in a ditch fill which was dated by radiocarbon to 435–605 ad, a date which matches other metalworking apparatus excavated, and the early establishment of a church and monastic community on this site.42 At Portmahomack, the first confirmed Pictish monastery, there was found a ‘cupellation tray’.43 This is illustrated in the original article on the excavations, and does appear to be a possible early porous pottery cupel of the sort used before the superiority of bone ash was commonly known. Both examples, the most certain sites for cupellation, belong to the early medieval period. There is one possible later medieval monastic site that shows clear evidence of cupellation predating the dissolution, the abbey of Strata Florida in Wales. Here monastic cupellation is evident through assay of the slag that was found near a smelting furnace in 1887, and the silver content in the excavated lead is so low that silver must have been extracted from it using industrial cupellation processes.44

41 

James, ‘Excavations at Carmarthen Greyfriars’, p. 168. Brown and others, ‘Excavations on Cathedral Hill’, pp. 116–17. 43  Carver, ‘An Iona of the East’, p. 3. 44  Hughes, The Cwmystwyth Mines, p. 5. 42 

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The relative scarcity of cupellation remains is likely due to pre-c.  1990 excavation reports, where there was a tendency simply to refer to cupels and other parting vessels as ‘heating trays’ which obscures those sites from any but the most exhaustive searches for cupellation remains. However, those sites where cupellation is indicated show that this chemical process was used to separate silver from lead as early as 435 ad in Irish and Scottish monasteries and that this use likely continued in monastic communities throughout the medieval period. As there is only one monastic site that has a vessel related to sublimation, an aludel from Byland Abbey, this process is less readily contextualized through physical evidence into the medieval history of chemistry than distillation or cupellation. Just as with distillation, there are several sites where sublimation could have been practised but cannot be confirmed. These include any site where ceramic cucurbits or distilling bases were found, although not glass examples as these would not survive the higher temperatures needed for sublimation. As this is wildly speculative these sites have not been included in this study. Because the one piece of evidence for sublimation from a British monastic site has not been fully published little can be concluded. However, it is extremely likely that alchemy was practised at Byland if this vessel can be confirmed as an aludel. This is because sublimation before the fifteenth century seems to be most commonly used in alchemical experimentation. The evidence for cupellation and sublimation is much scarcer than that for distillation. In the case of sublimation one factor contributing to this relative scarcity in the archaeological record is that its material correlates are easily confused for either distillation equipment, in the case of the base, or assorted domestic forms in the case of the aludel when it is broken. The use of sublimation, whilst known, is also not likely to have been an everyday or commonplace process on the scale of distillation and in fact its uses may have been very limited beyond alchemical experimentation before the fifteenth century. Indeed, the aludel from Weoley Castle, non-monastic though it is, had a mercury residue in the base which is an important alchemical metal.45 In the case of cupellation these arguments are less valid; its material culture is recognizable through both form and fabric in later medieval periods. In earlier periods the use of ceramic, instead of bone ash, complicates recognition but shallow crucible-like vessels with a porous fabric are likely candidates for cupels. The scarcity of cupellation vessels at monastic sites is possibly explained by the fact that in monastic precincts the only uses of cupellation that are likely are small-scale assaying of ores for economic 45 

Linnane and others, An Archaeological Overview of Weoley Castle, p. 8.

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or alchemical purposes. The best evidence for monastic phase cupellation comes from a site where only the waste of the silver extraction process was found. This perhaps suggests that this process can and should be recognized in other ways than through material culture.

Conclusions Evidence for chemical processes at twenty-three monastic sites has, through diagnostic material culture and secondary products, shown that distillation, cupellation, and sublimation took place at British monastic sites in the medieval period. Distillation is the best represented process, whilst the other two are considerably rarer. This is not surprising since distillation, whilst a chemical process, was also used in kitchens and other non-chemical contexts. Distillation’s chemical purpose at any site is complex to define but one of three explanations is likely: medical distillation, alchemical distillation, or metalworking. The uses of cupellation and sublimation are more simply defined. Cupellation is used to separate precious metals from base ones; especially silver from lead. Sublimation, in the medieval period, appears to be almost solely used in alchemical experimentation and may be the most conclusive single piece of evidence in the discovery of an alchemical assemblage. The lack of definite conclusions about the state of chemistry in monasteries within the British Isles is frustrating, but with more work, sites, and types of data being analysed it may in the future be possible further to specify what a chemical vessel was used for at any given site. It is worth mentioning that it is quite possibly futile to attempt to correlate too closely the specific purpose of chemistry at any medieval site with an equivalent modern discipline, because in contemporary medieval minds there would have been little to no differentiation between practices such as alchemy, pharmacy, or metallurgy.46 Whilst the specific uses or purposes of this apparatus may be beyond our ability to determine, and there is still much work to be done in this area, it can be concluded that overall chemistry at low levels does not seem to have been rare in monastic institutions throughout the British Isles. However, there is currently no evidence that it ever took the form of an independent alchemical, pharmaceutical, or metallurgical laboratory on the scale of Oberstockstall in Austria. As this article has examined the prevalence of chemical apparatus at British medieval monasteries only by examining published sites, it leaves many routes 46 

Martinón-Torres, Rehren, and Von Osten, ‘A 16th-Century Lab in a 21st-Century Lab’; Martinón-Torres and Rehren, ‘Ceramic Materials in Fire Assay Practices’, p. 148; MartinónTorres and Rehren, ‘Alchemy, Chemistry and Metallurgy in Renaissance Europe’, p. 14.

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for future study. The most obvious route for further investigation would be to include unpublished sites, or at least sites where the chemical material has not been published; an expanded database will allow better conclusions to be drawn. There are at least three sites already identified as possibly containing chemical material that are unpublished.47 In addition, reassessing the pottery and glass assemblages of pre-1960 publications could be valuable, as chemical vessels were often misidentified as things like oil-carrying pots in the case of the Carmelite friary in Nottingham.48 A final route would be to look at the chemical residues in the already identified and newly excavated material culture of chemistry as Marcos Martinón-Torres has done with material from Oberstockstall and the Old Ashmolean Museum, Oxford.49 This would allow a more nuanced conclusion to be drawn as to the specific purpose of chemistry at these sites. It is my hope that this paper succeeds in stimulating interest and work into the archaeology of chemical apparatus, not only in monastic contexts but throughout the medieval and early modern periods and does not simply become treated as the final work like Moorhouse’s paper has been for forty years.50 There is still much left to be learnt.

47 

Hailes Abbey, Gloucestershire (Moorhouse, ‘Medieval Distilling Apparatus’, p. 108); Haverholme Priory, Lincolnshire (Moorhouse, ‘Medieval Distilling Apparatus’, p. 113); Watton Priory, Yorkshire (Moorhouse, ‘Medieval Distilling Apparatus’, p. 113). 48  For example: Parker, ‘Nottingham Pottery’. 49  Martinón-Torres, Rehren, and Von Osten, ‘A 16th-Century Lab in a 21st-Century Lab’; Martinón-Torres, ‘Inside Solomon’s House’. 50  Moorhouse, ‘Medieval Distilling Apparatus’.

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