Experts at Harvard have confirmed that Houghton Library’s copy of Arsène Houssaye’s Des destinées de lame is bound in human skin. They are 99 percent sure that their tests are correct.
Here is more about the tests from the Harvard blog: “Microscopic samples were taken from various locations on the binding, and were analyzed by peptide mass fingerprinting, which identifies proteins to create a “peptide mass fingerprint” (PMF) allowing analysts to identify the source.”
The university also concluded that two other books which were suspected to be made of human skin were actually bound in sheepskin.