Latest tests on charred ancient papyri reveal the invention of metallic ink to be several centuries earlier than previously thought

Using the world’s largest and most sophisticated x-ray microscope, scientists have read a little deeper into one of the iconic relics of the ancient world: a library of charred scrolls that survived the eruption of Mount Vesuvius almost 2000 years ago.

Last year, researchers managed to decipher some of the letters on the carbonised papyri. Now, unexpectedly, they reveal in the Proceedings of the National Academy of Sciences that they have established that the scribes who copied the ancient texts knew the secret of metallic ink.

The find is unexpected because until now, historians had depended on the evidence left by the Roman historian Pliny the Elder – who himself perished in the eruption that destroyed the two cities of Pompeii and Herculaneum – that the Graeco-Roman world used an ink made from soot collected from wood furnaces.

Although metallic ink was used in the second century AD for writing secret messages, iron oak-gall inks were used on parchments only after 420 AD.

Facebook Twitter Pinterest The charred remains of the papyrus scroll from Herculaneum. Photograph: Emmanuel Brun/AP

Researchers at the European Radiation Synchrotron Facility – which houses an instrument that delivers x-ray beams 100 billion times brighter than anything used in a modern hospital – used a suite of techniques to peer into the Herculaneum papyri without damaging them. The papyri were first discovered in the 18th century: a collection 600 or 700 books tightly wound and then all but incinerated in the most devastating natural disaster of the Roman world.

In January 2015, scientists used the synchrotron accelerator to identify individual letters of the Greek alphabet and even whole words within the text: the latest probe found that the ink in which the scrolls were written contained high levels of metal, too high to be explained by contamination by water funneled through lead pipes, or from a copper inkpot or bronze container.

Such research offers scholars a chance to get a closer look at handwriting in the ancient world and opens up the possibility of reading texts long-since thought lost, or even of discovering hitherto unknown works.

But first, it offers an opportunity to study the ink-and-paper technologies of the Roman Empire in its heyday. And it reveals that the invention of metallic ink can be pushed back several centuries.

“For nearly 2000 years, we thought we knew everything, or almost everything, about the composition of antique ink used to write on papyrus,” said Daniel Delattre, of the French national science agency’s Institute for Research into the History of Texts, and one of the authors of the study.

“The highly specialised studies carried out at the European synchrotron show us that we must be wary of our ideas and that the ink also contained metal, notably lead in sizeable quantities.”

• This article was amended on 23 March 2016. An earlier version referred to evidence left by Pliny the Elder that the Graeco-Roman world used ink made from smoke collected from wood furnaces. That has been corrected to “ink made from soot”.