Place a little oxide of bismuth on a white dish, and pour over it some Harrowgate water. Its beautiful white colour will instantly be changed to black. It is well known that this oxide, under the name of pearl white, is used as a cosmetic by those of the fair sex who wish to become fairer. A lady thus painted was sitting in a lecture room, where chemistry being the subject, water being impregnated with sulphuretted hydrogen gas (Harrowgate water) was handed round for inspection. On smelling this liquid, the lady in question became suddenly black in the face. Every person was of course alarmed by this sudden chemical change; but the lecturer explaining the cause of the phenomenon, the lady received no farther injury, than a salutary practical lesson to rely more upon natural than artificial beauty in future."
Stories similar to this abound in the 19th century, in which a celebrated beauty is suddenly exposed as a cosmetics-user by the chemical reaction that turns bismuth oxide (a white powder) black. As a note: this same source, while including this story that preaches natural beauty over artificial, also contains the recipe to make bismuth pearl powder.
Source: Mackenzie's Five Thousand Receipts, 1829