Researchers at Harvard University have confirmed that one of the books in the Houghton Library, the school's rare-book collection, has been covered in a binding of human skin.
"Tests have revealed that Houghton Library's copy of Arsène Houssaye's "Des destinées de l'ame" ... is without a doubt bound in human skin," the library said in a blog post Wednesday.
Microscopic examination of samples from the binding were used to identify its source, experts said.
"The analytical data, taken together with the provenance of Des destinées de l'ame, make it very unlikely that the source could be other than human," said Bill Lane, the director of the university's Mass Spectrometry and Proteomics Resource Laboratory.
The tests ruled out other common binding sources including cattle, sheep and goat, he said.
French author Houssaye presented the book, the title of which translates as "Destinies of the Soul," to an acquaintance, a doctor, in the mid-1880s.
The doctor, Ludovic Bouland, then bound it using skin taken from the body of a patient at a mental hospital that had gone unclaimed.
The female patient had died from a stroke.
Binding books with human skin has been done since the 16th century, Harvard researchers say.
"The confessions of criminals were occasionally bound in the skin of the convicted," Harvard librarian Heather Cole explained, "or an individual might request to be memorialized for family or lovers in the form of a book."
The practice even had a name, she said; anthropodermic bibliopegy. Several examples are in the collections of libraries around the world.
Inside the Houssaye is a handwritten note of explanation from Dr. Bouland.
"This book is bound in human skin parchment on which no ornament has been stamped to preserve its elegance. By looking carefully you easily distinguish the pores of the skin," he wrote.
"A book about the human soul deserved to have a human covering: I had kept this piece of human skin taken from the back of a woman."
The book is the only one in the university's collection confirmed as having been bound in human skin. Two other volumes once thought bound the same way -- one in the university's law school and one in the medical school library -- have been shown to be covered in sheepskin.
The Houssaye volume was deposited in the Houghton collection in 1934 and permanently gifted to the institution in 1954.