Hundreds of papyrus scrolls were charred during the eruption of Volcano Vesuvius in 79 AD, and remained preserved unread in the National Library in Naples, Italy.
Most of these charred pieces are known as Herculaneum scrolls, and are so fragile that they are impossible to open and unfold. Researchers and citizen scientists are currently using X-ray techniques and advanced artificial intelligence to uncover the writings of ancient authors hidden within.
A new study, published in the scientific journal PLOS One on September 16, may provide additional evidence that may help achieve this goal. The researchers recreated papyrus scrolls with inks containing varying amounts of lead, and found that X-ray imaging could detect lead-containing ink, found in some ancient scrolls, more easily than non-metallic ink.
To date, only a few original scrolls have been digitally unfolded, and the results of the study may help determine which scrolls are most suitable for digital opening and deciphering them without destroying them.
“The scrolls are a lot like a piece of charcoal for a barbecue,” said the study's lead author, Douglas Sayler, a research volunteer at the University of California, Berkeley. “It's just carbon, and that's the problem with reading its text. The ink is made of soot.”
AI has difficulty detecting non-metallic ink because it becomes “dark carbon on dark carbon,” Seiler explained. But adding lead makes the ink stand out in X-ray images, making it easier for AI to spot the text.
He added that the next step is to test the original scrolls to determine what percentage of them contain lead. "They can tell within minutes if they check the coils one by one. The lead signal is very strong," he said.
So far, an entire scroll and sections of other scrolls have been deciphered, thanks to the Vesuvius Challenge, a project launched in 2023 that offers financial prizes to researchers who succeed in deciphering it.
Most of the rolls studied are the best ones, Seiler said, “beautiful rolls that look like toilet paper or a tissue roll, that is, symmetrical in shape.” But more than 600 scrolls have not yet been opened, and many of them in the Naples library are crushed and fragmented.
Seiler believes that the best way to digitally open and decipher these scrolls is to first look for lead.
Computer scientist Brent Sales, co-creator of the Vesuvius Challenge, first discovered metallic ink in Herculaneum scrolls in 2009, while studying one at the University of Kentucky in Lexington. In 2016, a study revealed the presence of lead in two fragmented rolls, suggesting that it was intentionally added to the ancient ink.
To see if lead might help decipher the scrolls, Seiler and his team recreated several scrolls using Egyptian papyrus and carbon ink similar to the one used in Pompeii. They wrote various texts on them, including passages from the Bible and scripts from Alfred Hitchcock films and "The Outer Limits," then wrapped and carbonized them in a low-oxygen oven to mimic the conditions that preserved the original scrolls during the eruption of Vesuvius.
The team sent the fake scrolls to researchers at the National Institute of Standards and Technology in Gaithersburg, Maryland, to decipher. Using X-ray tomography and digital opening techniques, the researchers were able to reconstruct the scrolls and read texts at different levels of lead concentration.
"In fact, they were able to detect the texts much more clearly than we expected," Seiler added.
The findings provide "a new opportunity to finally read some of Herculaneum's most complex scrolls," according to a journal press release. This method may also allow the AI to be further trained and improve its ability to read ancient texts.
The compositions of inks in Herculaneum coils vary widely, and some contain higher concentrations of metals, said Sells, a professor of computer science at the University of Kentucky. But he added that the generally low concentration of metals indicates that they got into the ink accidentally, and were not an essential component of it.
“Scrolls with metallic inks are somewhat easier to read using digital opening, but that does not mean that other scrolls are impossible to read,” Sells continued. “The Vesuvius Challenge has shown that artificial intelligence can detect traces of ink even in the most difficult scrolls.”
Sales, who was not involved in the study, expressed his admiration for the team's "enthusiasm and perseverance."
He added: "The scrolls found a way to survive, and we found a way to save them. If the lead, which accidentally got into the ink, helps reveal their content, this will be another miracle that brings their words back from the brink of extinction."
