I’ve read that elemental mercury is not particularly toxic. Some mercury compounds, that can be absorbed during digestion, destroy the liver. The ones that cannot be digested are harmless. Mercury compounds used to be used as a medication to alleviate the symptoms of syphilis. Don’t try this at home.
That's right - they helped reduce the chancres or sores.
Of course they were toxic in their own right.
Mercury was considered a state of the art cure for health problems in the early nineteenth century. The Lewis and Clark expedition took along a large supply.
This fact allowed modern archaeologists to precisely map out the expedition's route. They just went to potential sites and tested the soil. Whenever they found mercury contamination they knew they had located a latrine.
It is sometimes suspected that Lewis killed himself in the throes of syphilitic dementia. Or perhaps it was dementia caused by mercury poisoning. Or dementia caused by malaria. Or dementia caused by opium. Or it's possible that he was murdered.
Stories like Lewis's make me feel better about modern medicine. Although of course modern medicine has its own horror stories.