Nowadays, arsenic is given a pretty wide berth – the element is not known as the “king of poisons” for nothing. Its toxicity stems from its similarity to the life-sustaining nutrient phosphorus, which allows arsenic to enter and interfere with important chemical reactions in the body. The element also likes to mix with others, often forming deadly and imperceptible powders with no taste or smell.
However, this versatility is what made arsenic so ubiquitous in a variety of Victorian-era products, from home decor and wallpaper to clothing and books. When combined with copper oxide and lime, a striking compound called copper acetoarsenite, or emerald green, was formed.
“At the time, emerald green was the most colorfast, brilliant green dye available, and it was a very popular color with consumers,” says Melissa Tedone, conservator at the Winterthur Museum in Delaware. “No alternative dye could even come close to matching the intensity of the color.”
Toxic emerald green
Arsenic spread far and wide in bookbinding through its use as a dye. Because it was used at a time when manufacturers were using machines to produce books in bookbinderies large and small, Tedone estimates that as many as tens of thousands of books were bound in emerald green between the 1840s and 1860s. (Our understanding of 19th-century bookmaking is limited thanks to closely guarded trade secrets.)
Although a series of accidental arsenic poisonings towards the end of the era sparked debate about the substance’s safety, manufacturers were unlikely to have been quick to abandon the hue while demand for it was strong.
So in 2019, Tedone and her colleagues began testing hundreds of books from Winterthur and the Library Company of Philadelphia. About half of this contained lead; some others showed various heavy metals such as chromium and mercury. However, just over 10 percent has been found to contain arsenic Emerald green – a much greater health hazard for librarians, collectors, and researchers. This hazard is due not only to arsenic’s toxicity, but also because the powder tends to easily flake off a bond and become airborne if disturbed.
“The arsenic offset isn’t visible to the naked eye,” explains Tedone, “so a person handling an arsenic book wouldn’t necessarily see green pigment being deposited on their hands or other surfaces.”
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Identification of Arsenic Books
In response, the restorers launched the poison book project, an “ongoing inquiry into the materiality of Victorian-era publishers’ covers”. They use a number of non-destructive analysis techniques to identify arsenic books without damaging them: if X-ray fluorescence spectroscopy detects arsenic and copper together, a second method is mentioned Raman spectroscopy can confirm the presence of emerald green.
“It’s an important part of heritage work to analyze and better understand the collections we care about,” says Tedone, lead conservator at the Poison Book Project. “But we definitely don’t want to damage these materials in the name of research!”
More recently, the project has been expanded to include crowdsourced data. Thanks to the work of researchers from more than a dozen other institutions and private collections 101 arsenic books have been identified so far, says Tedone. to help the massive undertaking, the Poison Book Project is distributing bookmarks with safety warnings and images in various emerald green colors. By August, the project had distributed more than 1,500 bookmarks in 49 states and 19 countries around the world.
(Source: Winterthur Library/Print and Magazine Collection)
While nothing more than consuming an entire toxic tome would result in a severe case of arsenic poisoning, Exposure to copper acetoarsenite Particles can still irritate the eyes, nose and throat. For librarians and researchers, repeated interactions can cause more serious internal symptoms, such as dizziness and nausea. For these reasons, if you suspect you’re handling an emerald green-bound Victorian-era book, be sure to wear nitrile gloves, avoid touching your face, and wipe down all surfaces after you’re done. Then think request a color swatch bookmark just to be sure!