Level 1 — Absolute Beginner
Almost 2,000 years ago, a volcano called Vesuvius erupted near the Italian town of Herculaneum. Hot ash covered a library of paper scrolls and turned them black.
The scrolls are too fragile to unroll. For a long time, scientists could not read what was written inside them.
Now scientists have a new idea. Some old ink had a metal called lead in it. Lead shows up very clearly on special X-ray pictures.
To test this idea, scientists made their own new scroll. They wrote on it with lead ink, rolled it up, and burned it, just like Vesuvius did to the real scrolls long ago.
- volcano
- a mountain that can explode and send out hot ash and rock
- erupt
- when a volcano suddenly sends out ash, gas and rock
- scroll
- a long roll of paper or papyrus with writing on it
- fragile
- easily broken or damaged
- ink
- a colored liquid used for writing or printing
- lead
- a soft, heavy gray metal
- X-ray
- a type of picture that can show what is inside something without opening it
- ancient
- very old, from a long time ago
Level 2 — Elementary
In 79 CE, the eruption of Mount Vesuvius buried the Roman town of Herculaneum in hot ash and rock, carbonizing a large library of papyrus scrolls stored in a villa near the site and leaving them fragile and blackened, with both the ink and the paper made mostly of carbon.
Because the ink and papyrus share the same carbon based makeup, ordinary scanning methods have struggled for years to tell writing apart from the material it sits on, leaving many scrolls unreadable without physically unrolling them, which risks destroying them.
Researchers have now confirmed that lead based ink, used in some ancient writing, creates a much stronger signal in X-ray scans than plain carbon ink, since lead is up to 25 times brighter under X-ray imaging than the surrounding papyrus.
To test the idea safely, the team prepared model scrolls using lampblack ink mixed with different amounts of lead, had students write passages with reed pens, rolled the scrolls up, and heated them in a low oxygen furnace to recreate the conditions of the original eruption, then confirmed that X-ray fluorescence and X-ray CT scans could detect the lead at every tested concentration.
- carbonize
- to convert something into carbon or a carbon containing substance, often through heat
- villa
- a large and luxurious country house, especially in ancient Rome
- makeup
- the composition or constituent parts of something
- signal
- a detectable indication or output in a measurement or scan
- lampblack
- a fine black soot used historically as a pigment in ink
- reed pen
- a writing tool made from a hollow plant stem, used in ancient times
- furnace
- an enclosed structure used to produce very high heat
- X-ray fluorescence
- a technique that identifies elements in a material by measuring the X-rays it emits
Level 3 — Intermediate
The 79 CE eruption of Mount Vesuvius carbonized a substantial library of papyrus scrolls housed in a villa at Herculaneum, leaving behind blackened, structurally fragile objects that have resisted legible scanning for decades because their ink and the papyrus beneath it are both composed predominantly of carbon, rendering the two nearly indistinguishable to conventional imaging techniques.
A research team has now demonstrated that lead, an element present in some ancient inks, offers a practical way around this indistinguishability: lead based ink registers as dramatically brighter than surrounding papyrus under X-ray scanning, up to 25 times more so, making it possible in principle to detect writing without ever physically unrolling a scroll.
To validate the approach without risking any genuine Herculaneum artifact, researchers constructed model scrolls, preparing lampblack ink with varying lead concentrations, enlisting students to inscribe passages using period appropriate reed pens, rolling the completed scrolls, and subjecting them to a low oxygen furnace designed to replicate the intense heat and limited air of the original volcanic burial.
Subsequent X-ray fluorescence and X-ray computed tomography scans successfully detected lead at every concentration tested, including quantities as low as 25 micrograms per square centimeter, results that have led the team to propose a triage protocol in which scrolls are first screened with a handheld X-ray fluorescence instrument, with only those showing a lead signal advancing to the more resource intensive imaging needed to distinguish individual letters from the papyrus.
- indistinguishability
- the quality of being impossible or very difficult to tell apart
- register
- to be recorded or detected by an instrument or measurement
- validate
- to check or prove the accuracy or worth of something
- artifact
- an object made by a human, typically of historical or cultural interest
- inscribe
- to write or carve words or symbols onto a surface
- computed tomography
- an imaging technique that uses X-rays to build cross sectional images of an object
- triage
- the process of prioritizing items or cases based on urgency or likelihood of success
- resource intensive
- requiring a large amount of time, money or equipment
Level 4 — Advanced
The carbonization inflicted on Herculaneum's papyrus library by Vesuvius's 79 CE eruption has long presented a peculiar paradox for conservators and papyrologists alike: the very heat that rendered the scrolls too fragile to unroll also chemically homogenized their ink and substrate into a nearly identical carbon signature, defeating conventional imaging techniques that rely on contrast between the two to reveal legible text.
A research team's demonstration that lead, an element incorporated into some ancient inks for reasons likely unrelated to future legibility, generates an X-ray signal up to 25 times more intense than the surrounding papyrus reframes that paradox as a solvable engineering problem rather than an intractable one, since a sufficiently bright elemental signature can, in principle, be detected and mapped without ever physically disturbing the scroll's structure.
The methodological rigor of the validation is itself notable: rather than risking irreplaceable artifacts, researchers constructed analog scrolls, inscribing lampblack ink of graduated lead concentration onto fresh papyrus with period appropriate reed pens, then subjected the rolled specimens to a low oxygen furnace calibrated to approximate the intensity and limited combustion of the original volcanic burial, a controlled recreation that allowed lead detection thresholds to be established with a rigor no genuine Herculaneum fragment could safely provide.
The resulting triage protocol, screening candidate scrolls with a portable X-ray fluorescence instrument before committing any to the far more resource intensive computed tomography imaging required to resolve individual letterforms, represents a pragmatic acknowledgment that not every scroll in the collection was necessarily written in lead based ink, and that scholarly resources are better allocated by first identifying which specimens are even theoretically legible before attempting to read them.
- paradox
- a situation that seems contradictory but may contain a deeper truth
- substrate
- the underlying surface or material on which something is deposited or acts
- homogenize
- to make something uniform in composition or character throughout
- intractable
- difficult or impossible to solve or manage
- elemental
- relating to a chemical element in its most basic form
- analog
- something that serves as a comparable or parallel model for another
- calibrate
- to adjust or fine tune an instrument or process to match a required standard
- pragmatic
- dealing with things sensibly and realistically rather than theoretically
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