Obsessive opera fans are used to sorting their full-throated, passionate art form into categories—lyric or grand, Italian or French, opera buffa or opera seria. Now, from a very unlikely corner, comes another possibility: sorting them at the molecular level.
Years ago, Portuguese chemistry professor and opera aficionado João Paulo André started to notice that the operas he loved featured a surprising number of plots with potions and poisons. Sometimes the characters might intone the name of a specific substance; sometimes they would just describe an elixir whose effects could only be explained by a particular chemical. All in all, about a fifth of operas, André estimates, reach the heights of comedy, tragedy, and romance not only with music, acting, and costumes, but also with the help of substances like oxalic acid, arsenic, or a cyanogenic glycoside called amygdalin.