What if the best way to understand a 2,000-year-old burned scroll is to make one yourself and set it on fire?
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way → understand → fire
Scientists did just that to investigate how writing might be recovered from carbonised papyrus scrolls buried by the eruption of Mount Vesuvius.
uncertain
writing → do → Vesuvius
In a
study published in PLOS ONE, researchers created modern papyrus scrolls, wrote on them with ink containing different amounts of lead and then carbonised them in a low-oxygen environment.
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researchers → publish → environment
The experiments showed that leaded ink could stand out dramatically in X-ray scans, offering a possible way to identify ancient scrolls whose hidden writing may be recoverable.
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writing → show → scrolls
The experiment was designed around one of archaeology's most difficult collections: the Herculaneum scrolls.
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experiment → design → collections
When Mount Vesuvius erupted in 79 CE, volcanic material overwhelmed Herculaneum, an ancient Roman town near modern Naples, Italy.
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material → erupt → Naples
Among the material buried was a library containing more than a thousand papyrus scrolls.
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library → bury → scrolls
The extreme heat did not simply destroy the scrolls.
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heat → destroy → scrolls
Instead, it carbonised them, turning the papyrus into fragile, blackened objects.
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it → carbonise → objects
The process preserved the scrolls in a severely damaged state, but it also created a major problem for researchers: opening them can cause further damage or destroy them altogether.
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opening → preserve → them
The collection is especially important because it represents the only known intact library from antiquity.
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it → represent → antiquity
Many of the texts inside the scrolls may contain information that has never been read in the modern era.
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that → contain → era
Researchers have therefore been developing methods to look inside the scrolls without physically unrolling them.
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Researchers → develop → them
Why ordinary ink is difficult to see
One of the biggest challenges is the material itself.
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One → see → challenges
Ancient carbon-based ink and carbonised papyrus can look remarkably similar when examined using X-ray techniques.
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ink → base → techniques
Because both contain carbon, the contrast between writing and the surrounding papyrus can be extremely weak.
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contrast → contain → writing
That makes it difficult for X-ray CT scans to distinguish individual letters, even when the scans successfully capture the complicated layers of a tightly rolled scroll.
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scans → make → scroll
The Berkeley-led research explored whether a different ingredient in some inks could solve that problem: lead.
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ingredient → lead → problem
Lead is much denser than carbonised papyrus and interacts with X-rays differently.
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Lead → interact → rays
If lead is present in the ink, the written letters can produce a much stronger signal in an X-ray scan.
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letters → write → scan
The researchers found that the lead in their experimental ink absorbed up to 25 times more X-rays than the surrounding charred papyrus, making the writing stand out clearly.
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writing → find → papyrus
Students helped create the test scrolls
To test the idea, researcher Douglas Seiler sourced papyrus and reed pens and prepared ink containing different concentrations of lead.
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Seiler → help → lead
High school students were then asked to write passages on the modern papyrus.
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students → ask → papyrus
The material included lines from Star Wars, passages from the Bible and a quotation from the 1960s science-fiction television series The Outer Limits.
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material → include → series
The researchers then rolled the papyrus into scrolls and placed them inside a container with very little oxygen.
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researchers → roll → oxygen
They heated the scrolls in a high-temperature furnace, producing carbonised replicas designed to resemble the physical condition of the ancient Herculaneum material.
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They → heat → material
The point was not to recreate every detail of the ancient eruption.
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point → recreate → eruption
Instead, the model gave scientists something they could safely experiment on.
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they → give → something
Unlike a priceless archaeological artefact, the modern scrolls could be burned, scanned and processed repeatedly without putting an irreplaceable historical object at risk.
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scrolls → burn → risk
X-rays revealed the hidden writing
After carbonisation, the experimental scroll was examined using X-ray techniques.
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scroll → reveal → techniques
The researchers used X-ray computed tomography, or X-ray CT, to produce thousands of images that could be combined into a three-dimensional representation of the scroll.
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that → use → scroll
Because lead absorbs X-rays much more strongly than carbonised papyrus, the lead-containing letters appeared as significantly brighter features within the scan.
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letters → absorb → scan
The researchers reported that lead concentrations as low as 25 micrograms per square centimetre could be detected using both X-ray CT and X-ray fluorescence.
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concentrations → report → CT
This is important because it suggests that researchers may not need to begin by trying to decipher every surviving scroll individually.
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researchers → suggest → scroll
Instead, they could first screen the collection for evidence of lead-containing ink and then prioritise the scrolls where the X-ray contrast is likely to be strongest.
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contrast → screen → scrolls
From scanning to virtually opening a scroll
Detecting the letters is only part of the problem.
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Detecting → scan → problem
A scroll consists of many tightly packed layers of papyrus.
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scroll → consist → papyrus
Even if an X-ray scan captures the writing, researchers still need to separate those layers computationally and reconstruct the surface on which the letters were written.
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letters → capture → which
This is where virtual unrolling comes in.
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unrolling → come → ?
The researchers tested software originally developed to map the internal layers of lithium-ion batteries.
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researchers → test → batteries
…and 19 more, not listed.
The Aporia
