BEWARE THESE POISON BOOKS
TENS OF THOUSANDS OF BOOKS BOUND IN EMERALD GREEN BETWEEN THE 1840s AND 1860s ARE LACED WITH ARSENIC. A GROUP OF CONSERVATORS IS WORKING TO TRACK THEM DOWN.
NOWADAYS, we tend to give arsenic a wide berth — the element isn’t known as the “king of poisons” for nothing. Its toxicity stems from its similarity to the life-sustaining nutrient phosphorus, which allows arsenic to invade important chemical reactions in the body and disrupt them. The element is also happy to mix with others, often forming
deadly compounds with no taste or smell. Yet 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 arsenic trioxide is combined with copper acetate, it produces an eyecatching compound called copper acetoarsenite, or emerald green.
“At the time, emerald green was a wildly popular color among consumers,” says Melissa Tedone, a conservator at the Winterthur Museum, Garden and Library in Delaware and lead conservator for the Poison Book Project, an ongoing project to investigate Victorian-era book bindings. “No alternative dye could even come close to the intensity of the color.”
IN BOOKBINDING,
its use as colorant allowed arsenic to spread far and wide; Tedone estimates that as many as tens of thousands of books were bound in emerald green between the 1840s and 1860s. Although a series of accidental arsenic poisonings sparked debate over the substance’s safety toward the end of the era, she says, it’s unlikely that manufacturers would have been quick to give up the hue as long as there was strong demand for it.
So, in 2019, Tedone and her colleagues began testing hundreds of books from Winterthur and the Library Company of Philadelphia. About half of these contained lead; some others revealed different heavy metals, such as chromium and mercury. But just over 10 percent of the green-colored books were found to contain arsenic — a much larger health risk for librarians, collectors and researchers.
That hazard is not only due to arsenic’s toxicity, but because the powder tends to flake easily from a binding and into the air when disturbed. “The arsenic offset is invisible to the naked eye,” explains Tedone, “so a person handling an arsenical book wouldn’t necessarily see any green pigment offsetting onto their hands or other surfaces.”
In response, the conservators kickstarted the Poison Book Project, focusing on tracking down books bound in potentially toxic pigments. They use a number of nondestructive techniques to identify arsenical books without causing damage to them: X-ray fluorescence spectroscopy detects arsenic and copper, while a second method called Raman spectroscopy can confirm the presence of emerald green.
Thanks to the work of researchers from more than a dozen other institutions and private collections, 124 arsenical books have so far been identified, Tedone says. To help in the tremendous undertaking, the Poison Book Project distributes bookmarks with safety warnings and images of various emerald green colors. As of August, the project had distributed more than 1,500 bookmarks to 49 states and 19 countries around the world.
While nothing short of licking a toxic tome would lead to a serious case of arsenic poisoning, exposure to copper acetoarsenite particles can still irritate the eyes, nose and throat. For librarians and researchers, repeated interactions may cause more serious internal symptoms such as dizziness and nausea.
If you suspect you might be handling a Victorian-era book bound in emerald green, make sure to wear nitrile gloves, avoid touching your face and wipe down all surfaces after you are done. ( You can even request a specialized color swatch bookmark from the Poison Book Project, just to be sure.)