Arsenic? Really? That’s too easy, Potenza, because Arsenic (As) is the KING of poisons (1). First, it’s a metallic element, with an atomic number of 33, discovered in 1250 AD by the German Alchemist Albertus Magnus back when scientists were converting their names to Latin. Carola Potencia. Meh. Second, it’s inorganic, so unlike organic poisons, its toxicity doesn’t diminish with time because it doesn’t break down as easily.
And third, it’s also one of the MOST toxic substances on earth. In some forms, it’s pretty much odorless and tasteless, and therefore became the perfect vehicle to poison royalty and rats, and popes and paupers since the Middle Ages because it can be discretely slipped into food or drink, say, from a jeweled ring with a hidden compartment. (Looking at you, Lucrezia Borgia (2)). The toxicity of As has been known for far longer. References have been found in Ancient Egyptian papyri and ancient Greek philosophy. Ancient Chinese writings details its usage as a pesticide in rice fields (3).
But as civilization approached the 19th century, it was believed that As was only deadly if it was ingested or inhaled. (Wrong. It is also toxic when absorbed through skin.) This incorrect belief was incredibly problematic because when As was mixed with other metals and chemicals, it made the most beautiful and non-fading colors! Orpiment, a rich lemon yellow (4), is made from arsenic trisulfide; realgar, a brilliant red-orange pigment (5), is made from arsenic disulfide; and emerald green, an absolutely deadly copper-acetoarsenate (3Cu(ASO2)2.Cu(CH3COO)2), was used everywhere because it was cheap to make and didn’t fade over time (6). It dyed cloth for dresses, suits, and even socks, was extremely popular in printed wallpaper, and was used to decorate children’s toys (6), because, of course, children never put toys in their mouths. (I was trying to convey “eye-roll”. Did it work?)
And if it was being used to create gorgeous bright green cloth, why wouldn’t it be used in cloth-covered books, too? Not only that, but a 19th century librarian in Denmark conserved ancient manuscripts containing illuminated maps by coating the untainted bindings with emerald green arsenic-based paint to stop books from being destroyed from pests like mice and bookworms (7). Made sense since those animals were extremely destructive. Once modern archivists figured out the books were literally poisonous, they had them analyzed and even published a research paper about it (8).
Does that mean that you’re in danger from poison books? Well, yes, if you inherit a Victorian library from your great Aunt Mary or you visit a rare book collection and are interested in checking out bright green books from the mid-1800s—or bright yellow books or bright orange books. Because not all of these books are found in ancient European libraries. They could have been donated to a library near you and not yet been discovered. In fact, a group of librarian conservators in Delaware has created the wonderfully named Bibliotoxicology Working Group and the Poison Book Project (9). They have also developed a protocol for determining if a book is poisonous using a handheld X-ray fluorescence device, are creating a database, and safe-handling protocols (10).
Which brings me to a lovely line in one of my favorite movies, The Mummy (1999).
“It’s just a book. No harm ever came from reading a book.” (11)
Au contraire, mon ami.
As always, these are my own opinions based on my biases, knowledge, and understanding, and the websites I’ve linked are in no way an endorsement.