Croton oil. A laxative of extreme potency. A highschool chum told me about Balzac short story, where French King put croton oil into wine, and would not let afflicted courtiers depart until they were desperate. So they all perched on first stone wall they could find.
Alas I never knew name of the story, and can't find it
Perhaps in Comedie Humaine.
From AHD
croton oil

NOUN: A brownish-yellow, foul-smelling oil obtained from the seeds of a tropical Asian shrub or small tree (Croton tiglium) and formerly used as a drastic purgative and counterirritant. Its use was discontinued because of its toxicity