Part II 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 samples illustrate benzo colors after treatment with formaldehyde and metallic salts, coupled with parazole FB, and diazotized and developed. The text includes directions, dye concentrations and formulas, and information on color fastness.