Tag: silver

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Making a Silver Pot

Seuso silver situla or finger pot known as Hippolytus situla B, photo by Judit Andras-Kardos, Magyar Nemzeti Múzeum

In our last post, we were introduced by St. Augustine to the practices of fourth- and fifth-century Roman silversmiths. Augustine compares argentarii to pagan gods, who are all great at one thing. He would have preferred a single perfect artisan, competent in all areas. Let us now consider the production of a single object, created by many artisans during Augustine’s lifetime (CE 350-430).[1]

The object we have chosen is a situla, literally a bucket, in this case a small pale, surely a finger pot for washing hands at the dinner table. It is around nine inches (23cm) high. We have chosen it because there has been an excellent recent analysis of it, and objects with which it was found. It is part of a large hoard of silver, the Seuso Treasure – mainly highly decorated plates, jugs, and dishes – now displayed at the Hungarian National Museum, Budapest. This analysis allows us to make the observations that follow.

There are, in fact, two situlae showing complementary scenes from the story of Hippolytus and Phaedra. The situla we have chosen, Hippolytus situla B, comprises several elements, all of which required expert smithing.

Let us posit the following process of production: Silver was melted down, either from ingots or, far more likely, existing objects and coins were recycled; two silver sheets was formed by pouring the molten silver into a mould; a smooth inner liner, and the outer shell of the piece were formed from these sheets of silver by a vascularius. The inner liner was set aside, and the outer shell was then given its exquisite chasing, the scenes of Hippolytus and Phaedra, by a caelator. A flaturarius formed the lower and upper framing bands, the base, and perhaps the beaded rim. However, the beaded rim may have been made elsewhere since, as we shall see, it has a somewhat different silver content. In any event, it was formed with a punch. A crustarius formed the three feet in the form of gryphons, the two decorative handle ornaments, which are busts of emperors, and probably also the lozenged handle. This was done using the lost wax casting technique. The various elements – inner liner, outer shell, handle, feet, etc. – were soldered together. An inaurator then added gilding, including the golden sheen on the figures’ clothes, hair, and other features of the landscape, the bands at the base and upper rim. Finally a tritor buffed it to a high sheen.[2]

Each of these silver-workers worked in an atelier that was, let us imagine – excavations suggest we would not be far not wrong – hot, full of fumes, and had poor ventilation. The melting of metals released various toxins into this workshop, while other escaped through chimneys, spreading across the broader city, its hinterland, and many miles beyond. Silver itself is relatively benign. Repeated exposure to silver particles causes the skin and body tissues to turn grey or blue-grey, a condition known as “argyria.” Ingesting high levels of silver may cause the heart to enlarge and stomach irritation, and breathing in silver particles causes throat and lung irritation. Copper was added to a great deal of Roman silver plate, to improve its mechanical properties. That is, adding copper makes the silver harder, more durable, and easier to work mechanically (i.e. with a hammer, rather than casting). Today we know the silver-copper alloy as sterling silver (typically 92.5% silver, 7.5% copper).

XRF analysis of the Seuso situla shows that the body, handle and feet all contains between 2% and 3% copper, compared to around 95% silver. However, the upper beaded rim, has much less copper, no more than 0.5%, with 99% silver. This tells us that molten copper was added to the silver after it was refined to ensure it was better able to withstand hammering, shaping and chasing. Exposure to copper fumes “causes upper respiratory tract irritation, metallic taste, nausea, and metal fume fever.”[3]

The same XRF analysis shows that each piece of the situla contains very small amounts of lead, between 0.2 and 0.5%. All Roman silver contains lead, usually between 0.5 and 1%. It took a little effort to refine silver to that standard, by a process known as cupellation. It took a great deal more to refine it still further. Evidently, the silver in this situla was refined again to produce very high quality silver before the right amount of copper was added. This may have been done using a process known as liquation, whereby silver is melted together with lead, forming a lead-silver alloy that separates from other metals, including copper. This alloy is then subjected to further cupellation. Roman silver production, including recycling, always involved a great deal of lead. Melting lead releases lead aerosols that are highly toxic.[4]

There was, however, something even worse than lead in the workshop, and its immediate vicinity: Mercury. The XRF analysis has identified mercury in the thin layer of gold applied by the gilder. This proves he used a method known as fire gilding, whereby liquid mercury is mixed with gold and then heated, releasing the mercury into the atmosphere and adhering the gold. Mercury is a powerful neurotoxin, ultimately deadly to the fire-gilder. It is “toxic to the central and peripheral nervous systems. The inhalation of mercury vapour can produce harmful effects on the nervous, digestive and immune systems, lungs and kidneys, and may be fatal.”[5] Like lead aerosols, mercury was carried away by the wind and deposited by rain, contaminating the soil and vegetation many miles from its source. A recent study of Roman age skeletons in Spain, over a 70-year period, consistently had more than twice as much mercury and lead as bones of those who lived in the same place afterwards.[6] There is no indication that these were metalworkers. Rather, abundant evidence makes it clear that Roman-age metallurgy had a massive deleterious effect on human health and the environment.[7]

[1] The choice of the Seuso situla was entirely due to the excellent new publication: V. Mozgai et al., “Non-destructive handheld XRF study of archaeological composite silver objects – the case study of the late Roman Seuso Treasure,” Archaeological and Anthropological Sciences 13:83 (2021), 20 pages.

[2] D. E. Strong, Greek and Roman Gold and Silver Plate (Ithaca, NY: Cornell University Press, 1966), 7, 14-16. On silver beaded rims see Richard Hobbs and Laura Perucchetti, “Beaded rims on silver plate vessels in late Roman Britain and beyond,” Britannia 53 (2022), 385-401.

For an instructive video on the creation of a Roman silver cup:

[3] CDC: https://www.cdc.gov/niosh/idlh/1317380.html

[4] Very generally, see Paul Stephenson, “Ancient Roman Pollution,” Lapham’s Quarterly, February 23, 2022.

[5] The approach to this sad fact to date is captured in a sentence by a scholar of silver-smithing: “[Fire-gilding] is a durable and economical use of gold, and the health hazards of mercury were not given the consideration that they are today.” See The Hoxne Late Roman Treasure: Gold Jewellery and Silver Plate, ed. Catherine Johns (London: British Museum Press, 2010), 186.

[6] O. López-Costas et al., “Human bones tell the story of atmospheric mercury and lead exposure at the edge of the Roman world,” Science of the Total Environment 710 (2020), 136319 (7 pages). Here bones from two adjacent cemeteries at A Lanzada in northwestern Spain showed that Romans (first to fifth centuries CE) absorbed twice as much lead and mercury as those who came later (fifth to seventh centuries). Isotopic analysis suggests that 70- 80% of this came from atmospheric lead pollution (and the remainder from local geogenic lead sources).

[7] J. Montgomery et al., ‘“Gleaming white and deadly”: using lead to track human exposure and geographic origins in the Roman period in Britain’, Journal of Roman Archaeology, supplementary series, 78 (2010), 199-226, at 209: “From the 1st c. A.D., some individuals exhibit enamel lead concentrations of up to 30 mg kg-1. These individuals have a level of lead that is 10,000 times higher than that of the least polluted individual in this study: the Early Bronze Age skeleton from Gristhorpe (Yorkshire) (3 μg kg-1; Table 11.3). According to the ratio above, an enamel lead concentration of 30 mg kg-1 would arise from a blood lead level of c.300 μg dL-1, which is far higher than the ~100 μg dL-1 associated with “very severe poisonings”. J. Moore et al., ‘Death Metal: Evidence for the impact of lead poisoning on childhood health within the Roman empire’, International Journal of Osteoarchaeology 31 (2021), 846-56: “This study includes 173 individuals (66 adults and 107 non-adults) from five sites, AD 1st–4th centuries, located throughout the Roman Empire. Results show a negative correlation between age-at-death and core tooth enamel lead concentrations.

This is the third and last of three posts that formed part of a short lunchtime lecture delivered at the Humanities Institute, Pennsylavania State University, in February 2023.

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Roman Silversmiths

An etching of the Monumentum Liviae, a burial chamber built and maintained by and for slaves and freed slaves of the imperial household

In our last post we met Agatho, a silversmith who lived at the time of Augustus. At exactly the time Agatho died (c. 25 CE), Livia, the widow of Augustus, maintained a columbarium, a burial chamber, used exclusively for interring her own slaves and freedmen and those of her immediate family who lived in or near Rome (and not at their vast estates elsewhere). This facility, today called the Monumentum Liviae, was run by some of her Rome-based slaves and freedmen. The dead included three freed and two enslaved goldsmiths (aurifices), a silversmith (argentarius), an enslaved gilder (inaurator) who belonged to one of Livia’s freed smiths, and a margaritarius, who set her pearls in gold or silver. All of these precious metal workers were men, but there is a record of the burial at contemporary imperial columbarium, the Monumentum Marcellae, of an enslaved female silver-worker who belonged to an unspecified Augusta, probably not Livia. Here there were three more silversmiths and another named as a chaser or engraver (caelator), a silversmith who raised designs on metalwork or carved designs into them. Agatho is portrayed with the tools of the chaser, and a cup with a raised figure.[1]

As we can understand from this partial list of jobs, the production of silver goods was broken down into many sub-specialisms of greater and lesser skill. We have not so far mentioned others, like vascularii, who shaped sheet metal into forms; flaturarii, who cast and attached basic elements, like handles and bases; crustarii, who cast and attached more decorative elements; and tritores, polishers. We even have an account by St. Augustine of how silversmiths worked, a metaphor for polytheistic religion, where many gods looked after specialist areas.

“We laugh indeed when we see pagan gods distributed by the whimsy of human opinion to tasks divided amongst them, just like … craftsmen in the quarter of the silversmiths, where one vessel passes through the hands of many artisans in order to come out perfect, even though it could have been completed by one perfect artisan. But it was thought necessary for a multitude of artisans to be consulted for no other reason than this, namely so that each artisan might learn one part of an art quickly and easily, and so that they would not all be compelled, slowly and with difficulty, to become perfect in a whole art.”[2] 

Augustine does not tell us about enslaved silversmiths, but we can be sure that four centuries after Agatho’s death, many such artisans were enslaved or freed. We know a great deal about slavery in Augustine’s time from his own writings, including a letter discovered in the 1980s that details the mechanics of the later Roman slave trade, describing “an endless river” of people.

We might imagine that slaves of the imperial household were relatively well cared for in life, since some care and thought was afforded to them in death. However, we should not doubt that most enslaved artisans led hard lives, frequently undertaking dangerous tasks in poor working conditions. They worked with materials and undertook processes that damaged their eyes and teeth, skin, hands and wrists, joints and backs, lungs and organs. Repetitive tasks caused fractured bones, joint deterioration and arthritis. Anyone working with metals risked serious burns, respiratory damage, and the many consequences of heavy metal poisoning. We shall return to this in our next post, looking at a single object and the health consequences of its production.

[1] D. E. Strong, Greek and Roman Gold and Silver Plate (Ithaca, NY: Cornell University Press, 1966), 7, 14-16. Strong also comments on the Guilds of Silversmiths in Rome and other cities, and the fact that Nero is supposed to have created 150-200 new buildings for a silversmiths quarter. On the Monumentum Liviae, see Susan Treggiari, “Jobs in the household of Livia,” Papers of the British School at Rome 43 (1975), 48-77, at 54-5, 68, and note 91. See also J. M. C. Toynbee, “Some notes on artists in the Roman world, 5: Metal-workers, gem-engravers and medallists,” Latomus 9/iv (1950), 389-94, at 390, for Protogenes and Zeuxis, two freedmen employed as silversmiths in Augustus’ household. Toynbee comments on the fact that many such artisans, like Agatho, had Greek names.

[2] Augustine, De Civ. Dei 7.4; cited by Cameron Hawkins, Roman Artisans and the Urban Economy (Cambridge: Cambridge University Press, 2016), 66. Pace Augustine, it is likely that a silversmith worked his way through the skills, as a trainee chef might in a kitchen, before settling on his specialism.

This is the second of three posts that formed part of a short lunchtime lecture delivered at the Humanities Institute, Pennsylavania State University, in February 2023.

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Agatho the Silversmith

Funeral portrait carved for Agatho in around 25 CE,

In an earlier post we drew attention to the exhibition Hear Me Now! which has recently closed at the Met. There is no known Roman equivalent of David Drake, known as Dave. Although we know so little about him, still the details of Dave’s life can be contested. All we know for certain about Agatho the silversmith is what he had carved into his funeral portrait (c. 25 CE), which is now in the Getty Villa.[1] An inscription below his bust reads “Publius Curtilius Agatho, freedman of Publius, silversmith,” reminding us that Agatho lived and died with his former master’s name preceding his own, but also that he was proud of his trade. Agatho is shown holding a smith’s mallet and chisel, and also a small silver cup, presumably one he made himself. We can just make up a raised design of a figure, which may be a dancing satyr, not unlike the design on a silver wine cup, the Vicarello Goblet, made at exactly this time and now displayed in the Cleveland Museum of Art.[2]

The number of Roman slaves who could be granted freedom – manumitted – in any year was restricted in Agatho’s lifetime. After 4 CE (Lex Aelia Sentia), according to the wish of the emperor Augustus (d. 14 CE), the master must be at least twenty, and the slave at least thirty years old, at the time of manumission. By the age of thirty, we might guess that Agatho had been a silversmith for two decades. We can also guess that part of the price of his freedom was a legally-binding commitment to providing Publius Curtilius with a proportion of his skilled labor for free for the rest of his life (operae libertorum); by “his life,” I mean Agatho’s life, for the gift of free labor might be inherited by Publius’ heir if that was specified in the contract that Agatho signed. In other words, skilled freedmen like Agatho might be offered the opportunity to purchase their freedom for credit rather than cash; and although legally they were freedmen, only death would free them of their debt of work.

Agatho would have owed only part of his time to Publius. If Agatho earned enough money from other work, then he may have been able to delegate his operae libertorum to a silversmith of equal skill, perhaps one he trained himself, whom he paid. That skilled worker could not have been another of Publius Curtilius’s slaves, of course. This may have included Agatho’s own children, if they were before Agatho’s manumission. Any child Agatho fathered after his manumission would be freeborn, although not without some restrictions to what he might achieve as a citizen. Finally, if Agatho made enough money, as a freedman he would be permitted to own his own and train his own slaves. There are 197 references in Justinian’s Digest of Roman law concerning operae libertorum that address these various scenarios.[3]

[1] Grave Relief of a Silversmith, Getty Villa: https://www.getty.edu/art/collection/object/104034

[2] John D. Cooney. “The Vicarello Goblet”, The Bulletin of the Cleveland Museum of Art 54/ii (1967), 36-41, which notes traces the history of the goblet since its discovery in 1862 and notes that basic analysis of the silver was undertaken in 1966/7.

[3] Cameron Hawkins, Roman Artisans and the Urban Economy (Cambridge: Cambridge University Press, 2016), 130-91.

This is the first of three posts that formed part of a short lunchtime lecture delivered at the Humanities Institute, Pennsylavania State University, in February 2023.

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Ice cores

A scientist studying an ice core exctracted from Law Dome glacier, Antarctica

Just a note on something icy on a hot summer day. As we wrote in New Rome, in a section excerpted in Lapham’s Quarterly, Roman age smelting of silver-lead ore has left signals across the North Atlantic world in the form of anthropogenic heavy metal contamination of soil, sediment, and ice. Cores extracted from glaciers in Greenland and the Arctic show a sudden and dramatic rise in the deposition of atmospheric lead pollutants between c. 100 BCE and CE 100.

Lead is released by the smelting of a range of metallic ores, including those mined for copper and gold, tin, zinc, and silver, and from lead itself. In each location the levels of lead pollutants fall away rapidly toward 400, only beginning to rise again after 800, and not reaching Roman levels until c. 1700. In none of these locations is there any evidence for contemporary mining and smelting of metallic ores, which would have produced the contamination.

Roman-age pollution in the North Atlantic world is the direct result of fluctuations in the intensity of smelting that took place thousands of kilometers to the south, releasing into the atmosphere lead aerosol particles that were conveyed great distances within the northern hemisphere’s atmospheric transport system and deposited by precipitation. The origin of the lead in Greenlandic ice has been confirmed by geochemistry (isotope analysis). Spain was the source of up to 70 percent of the heavy metal pollution at its peak in the first century. Contamination is far greater the closer one gets to its source. In an ice core taken from the Col du Dôme glacier in the French Alps, the magnitude of lead contamination is one hundred times greater than that recorded in Greenland in the first century BCE, reaching a lower peak in c. 100, before falling steadily and dramatically to its lowest point in the sixth century.

In contrast, there are no spikes in lead pollution evident in any of ice cores extracted in Antarctica before around 1890. There is a steady, gradual increase in lead concentrations, reflecting the emergence of metallurgy in the southern hemisphere after CE 1500. Concentrations of lead triple from ~0.6pg g-1 in CE 1650 to ~1.8pg g-1 in CE 1885, then triple again to ~5.4pg g-1 before 1900. The isotopic signature of the lead relates it directly to the commencement of silver-lead mining at Broken Hills, and smelting at Port Pirie, in southern Australia.

According to a team of scientists, principally from the Desert Research Institute:

Concentrations remained high until the late 1920s, with a temporary low during the Great Depression (~1932) and again at the end of WWII (~1948) when concentrations dropped back to mid-19th century levels. Concentrations increased rapidly to 5.7 pg g−1 by 1975 and remained elevated until the mid-1990s. Concentrations during the early 21st century were ~3.7 pg g−1 lower than the peak 20th century concentrations but well above background levels before the start of the Industrial Revolution.(1)

This study draws on sixteen separate cores “from widely spaced coastal and interior sites”. It confirms and expands earlier, similar findings from a study of only the Law Dome glacier.(2)

The contrast between northern and southern hemisphere lead pollution highlights the scale and impact of Roman age smelting.

Notes

(1) J. McConnell et al., ‘Antarctic-wide array of high-resolution ice core records reveal pervasive lead pollution began in 1889 AD persists today’, Scientific Reports 07/2014: 4: 5848, 5 pages.

(2) P. Vellelonga et al., ‘The lead pollution history of Law Dome, Antarctica, from isotopic measurements on ice cores, 1500 AD to 1989 AD’, Earth and Planetary Science Letters 11 (2002), 291-306

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