Both Scheele’s green and Paris green found a second use as rat poison and insecticide, which tells you something of their toxic nature. [3] Then birder asked me if I had heard of the Poison Book Project. The University of Delaware and Winterthur Library and Museum came together to identify such books in the brilliantly named Poison Book Project. As of September 2022, the Poison Book Project had identified 101 books in libraries across the world that contained Paris green. Poison Book Project.