The danger of this old book was not hidden in its pages.

At the Winterthur Library, Melissa Tedone examines the green canvas cover of a 19th-century book, Rustic Adorments for Homes of Taste. The coating does not behave like the other tinted canvases she knows. This difference makes him consider a pigment already used in some old wallpapers.

The analysis conducted by Rosie Grayburn reveals copper acetoarsenite, a compound containing arsenic. Other volumes of the collections then give comparable results. The investigation is therefore not about a criminal plot printed in the book, but about a material used to give it a beautiful color.

These findings feed into the Poison Book Project, which is dedicated to identifying dangerous pigments in ancient books. They do not allow to condemn each green work: a shade alone does not replace an analysis. The reversal remains striking, since the conservation work here must protect both the book and the people who handle it.