Imagine, within your grasp, a scroll from the first-century AD, holding the secrets of the long-gone past. Unfortunately, this rolled-scroll was buried by Mount Vesuvius, the same volcano that obliterated Pompeii, and is nothing but a charred and burnt relic that could crumble if the wind blew the wrong way. The scroll is not the only one of its kind, either. It belongs to a remarkable library in Herculaneum, containing around 1,800 parchments. Like Pompeii, Herculaneum was buried by ash when Vesuvius erupted in 79AD. It wasn't until the 18th century that Herculaneum's library - the last standing ancient library, for that matter - was excavated. When that happened, various intact contents were brought to light for the first time in many many centuries. Of course, in the two hundred years since then, scientists have been trying to read the scrolls without damaging them. For example, several strategies involved delicately unrolling the scrolls and writing down what they could before the ink disappeared in the modern air, no longer preserved. Some of these fragments were even read successfully, mostly during more recent years, thanks to the help of infra-red camera technology. Most of the scrolls that have been unwound so far have been philosophical prose and poetry that had been lost to modern schools until now. But the method of unwinding the scrolls, even carefully, was damaging much of the ancient works, and it was decided that an alternative technique needed to be put in place. Since then, scientists have also tried looking inside the scrolls using CT scans. This technique was able to reveal the shape and layers of papyri, but, sadly, couldn't decipher the words inked upon them. Some other people tried to look inside the scrolls with CT scans, revealing the shape of the ancient, coiled layers, but they weren't about to decipher the contents. But the amazing thing about people is their curiosity, their thirst for knowledge - especially when it comes to history. And it is thanks to this inquisitiveness (and 3D X-ray imaging technology), that physicists were able to distinguish ink from paper, even deep inside the scroll. Using this kind of technology means that the scrolls don't have to be unfurled and, therefore, won't be damaged. The team is being led by physicist Dr Vito Mocella from Naples' CNR-IMM (Council for National Research for Microelectronics and Microsystems) and their work is published in Nature Communications . Dr Mocella came up with the idea of X-ray phase-content tomography being adapted for use on ancient scrolls when he was on a visit to France. "I was in Grenoble for a collaboration, and they explained to me some new developments using phase-contrast for science, for paleontology," he said. "They sounded like exotic applications, and I said, 'I have another idea.'" A regular X-ray machine works by measuring how much X-ray light shines through different parts of tissue in the body. But when X-rays pass through an object, they become slightly slowed or distorted, and it is this that the new X-ray takes advantage of. The distortion can occur because of the tiniest variations, and measuring the differences - "phase contrast" - can actually produce a very detailed, 3D picture of inside the scroll. The tiny bumps on the papyrus from a long-ago pen and ink were the key to revealing what the scrolls had to say.
The team found that the carbon-based ink wasn't very chemically different to the carbonised paper it was used on. But because the papyrus didn't actually absorb the ink, the liquid sort of sat on the surface. When it came to deciphering what they found, a lot of time and guesswork had to be used. You have to remember, the scroll wasn't just rolled but also slightly crushed from surviving being blasted by 300°C (572°F) heat and the chaos ensuing Vesuvius' eruption. On top of this, the fibres of the papyri were in grid form, disguising many of the straighter strokes of the letters. This meant that curved letters were easier to pick out. "I don't think the technique is perfect," Dr Mocella pointed out, adding that he and his team are already working on ways to improve upon the method. The project is one that Dr Mocella and his team are very passionate for - it is not about the ability to read the individual scrolls, but what these parchments symbolise. "Regardless of the individual text, the library is a unique cultural treasure," Dr Mocella explained. "It is the only ancient library to survive almost entire, together with its books. "It is the library itself that confers the status of exceptionality."
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