Whimsical illustration of mice in a laboratory with glassware, apparatus, and a Bunsen burner. Beatrix Potter was a niece of the author, Henry Roscoe, and created this illustration as a gift. The illustration is based on a quote from a text-book Roscoe and Joseph Lunt wrote. The text-book was Inorganic Chemistry for Beginners first published in 1893. The quote is included in the lesson on the ammonia compound, "The peculiar pungent smell of this compound is noticed if we heat a bit of cheese in a test-tube."
Roscoe, Henry E. (Henry Enfield). “A Dream of Toasted Cheese.” Paper. The Life & Experiences of Sir Henry Enfield Roscoe ... Written by Himself. London, England: Macmillan Company, 1899–1906. https://digital.sciencehistory.org/works/f4752h79r.