A poison given to the accused to determine guilt or innocence. Like a witch trial, the idea behind the ordeal poison was that the guilty would die and the innocent would live when dosed.
I had always thought that ordeal poisons were another example of superstition and dubious science until I ran across a webpage which said explained how the Calabar Bean (Physostigma venosum) was used as an ordeal poison in (what is now) Nigeria:
The traditional use of this poison has some scientific basis since, if the infusion was
nervously sipped by the guilty, a considerable amount of physostigmine would be absorbed
though the gut. On the other hand, if an innocent person boldly drank a large volume, this
would result in rapid violent vomiting and little of the alkaloid would be absorbed.
http://enviro.mond.org/9901/990115.html
(For the curious, physostigmine is an alkaloid which slows neurotransmitter break down, leading to over-exicitation of the muscles and brain. Currently physostigmine is being used to try to treat Alzheimer's Disease)
So maybe ordeal poisons did work as a psychological experiment, rather than a physiological one.
Me, I'll take my chances with a jury.
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