Libraries across the world have taken books with striking green covers dating from the 19th and early 20th century and put them behind locked doors due to fears they contain arsenic.
Now scientists at the University of St Andrews have developed a cheaper and easier way to analyse the pigment in the books, to distinguish the toxic copper acetoarsenite from other greens.
The new method involves using a hand-held vis-IR spectrometer to analyse the reflectance spectrum of the pigment, looking for a strong green band and a second band in the near-IR range.
This news could see tens of thousands of books returned to public display, although many others containing the poison pigment will remain locked up for the foreseeable future.
