Damn, dude did really research on biological and chemical properties of the it as well as historical facts.The author's post-chapter notes refer to it as a type of plant fertilizer (you can see her using it as intended on page 28) but when I was first reading I assumed they might've been naphthalene balls (which would've been used back then to throw in stored clothes to prevent moth and mold infestations and serve as a general pesticide, human consumption of it in notable quantity would destroy blood cells and cause hemorrhages in the eyes and face).