Part I of a sample book from Farbenfabriken vorm. Friedrich Bayer & Co.—the first incarnation of the modern pharmaceutical company Bayer AG established to manufacture and sell synthetic dyestuffs—containing mounted dyed yarn and cotton thread samples. Benzo refers to benzene, indicating the chemistry of direct cotton color from coal-tar derivatives. The sample colors move across the color spectrum, and the text includes directions, dye concentrations, and information on color fastness. Two cards with green and blue yarn samples contain handwritten percentages of dye concentrations and formulas. Additionally, two lists describing benzo and para color dyes have been kept with the book.