Slide showing two chemical compounds in microscopic view. Slide shows two chemical compounds in microscopic view. Top compound is labelled 'D'. This compound also has labels 'i.n.p.' to the lower right side of the compound and 'h.n.p.' to the top of the compound. Bottom compound is labelled 'E', and has additional labels 'i.n.t.' to the left side, and 'h.n.t' to the right side. Title below images reads: 'Fig 92 (continued) - D. Oestrone. E., 1:2-dihydroxy-1:2-di-2-naphthyl-acenaphthene'. Late 19th to early 20th century