National Geographic takes a look at the Poison Book Project, started by Winterthur Conservator and WUDPAC Affiliated Associate Professor Dr. Melissa Tedone to address toxic pigments in library collections. From the April 28, 2022 article by Justin Brower:
Libraries and rare book collections often carry volumes that feature poisons on their pages, from famous murder mysteries to seminal works on toxicology and forensics. The poisons described in these books are merely words on a page, but some books scattered throughout the world are literally poisonous.
These toxic books, produced in the 19th century, are bound in vivid cloth colored with a notorious pigment known as emerald green that’s laced with arsenic. Many of them are going unnoticed on shelves and in collections. So Melissa Tedone, the lab head for library materials conservation at the Winterthur Museum, Garden & Library in Delaware, has launched an effort dubbed the Poison Book Project to locate and catalogue these noxious volumes.
To date, the team has uncovered 88 19th-century books containing emerald green. Seventy of them are covered with vivid green bookcloth, and the rest have the pigment incorporated onto paper labels or decorative features. Tedone even found an emerald green book on sale at a local bookstore, which she purchased.
While these poisonous books would likely cause only minor harm unless someone decided to devour a nearly 200-year-old tome, the alluringly vibrant books are not totally without risk. People who handle them frequently, such as librarians or researchers, may accidentally inhale or ingest particles that contain arsenic, which could make them feel lethargic and light-headed or suffer from diarrhea and stomach cramps. Against the skin, arsenic can cause irritations and lesions. Serious cases of arsenic poisoning can lead to heart failure, lung disease, neurological dysfunction, and—in extreme situations—death.
So just how common are these poison green books? “It's somewhat hard to predict because our data set is still small, but I would certainly expect there could be thousands of these books around the world,” Tedone says. “Any library that collects mid-19th-century cloth publishers' bindings is likely to have at least one or two.”
A color to die for
Emerald green, also known as Paris green, Vienna green, and Schweinfurt green, is the product of combining copper acetate with arsenic trioxide, producing copper acetoarsenite. The toxic pigment was commercially developed in 1814 by the Wilhelm Dye and White Lead Company in Schweinfurt, Germany. It was used everywhere, from clothing and wallpaper to fake flowers and paint. To say that Victorian England was bathed in emerald green is an understatement: By 1860 more than 700 tons of the pigment had been produced in the country alone.
Arsenic’s toxicity was known at the time, but the vibrant color was nevertheless popular and cheap to produce. Wallpapers shed toxic green dust that covered food and coated floors, and clothing colored with the pigment irritated the skin and poisoned the wearer. Despite the risks, emerald green was ingrained into Victorian life—a color to literally die for.
While toxic green goods flooded parts of Europe and the United States, another invention transformed the bookmaking industry. Early 19th-century books were handcrafted, leather-bound artisan creations, but the industrial revolution quickly provided a way to mass produce books for a growing population of readers.
Poison in the library
In the spring of 2019 Tedone received a request from a curatorial fellow at the Winterthur gallery to borrow a book from the library to put on display: Rustic Adornments for Homes and Taste, published in 1857.
“This particular book was very beautiful, bright green with lots of gold stamping. It was very visually stunning, but it was in really bad condition,” Tedone says. “The spine and the boards were falling off, and the sewing had broken, so it needed to be conserved before it could go on exhibit.”
With the beautiful yet broken book under the microscope, Tedone peered at the front board. “There was a black, waxy excretion on the surface, and I was trying to pick it off of the bookcloth with a porcupine quill,” she says. “And then I noticed the colorant in the bookcloth was flaking off really easily around the area where I was working.”
To the untrained eye, this might seem normal for a 162-year-old book, but to Tedone it was surprising. “It didn’t seem like the cloth was dyed,” she says. “It seemed to me that maybe the starch coating on the cloth was mixed with a pigment.”
To learn the identity of the mysterious green pigment, Tedone turned to Rosie Grayburn, head of the museum’s scientific research and analysis laboratory.
Grayburn first studied the sample with an x-ray fluorescence spectrometer, which bombards material with x-rays and measures the energies of emitted photons to determine its chemical composition. This technique can tell you the elements that are present, but not how they are arranged in a molecule. Another technique using a Raman spectrophotometer measures how light from a laser interacts with target molecules, shifting the energy of the laser up or down. Much like each person has unique fingerprints, every molecule has a characteristic Raman spectrum.
The sensitivity of these techniques is key, but equally important is that they are nondestructive. “You shouldn’t be damaging works of art,” Grayburn says.
X-ray fluorescence revealed the presence of both copper and arsenic in the green pigment, a key finding, and the unique fingerprint from Raman spectroscopy positively identified the pigment as the infamous emerald green.
To learn more about dangerous pigments in collections, visit the National Geographic website for the full article.
