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Mercury: The Liquid Metal That Poisons

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While tracing the composition of a poison used at court, Maomao pauses on one ingredient in particular. Every other component, she notes, is easy to find, except one: quicksilver, that is, mercury. Its rarity and cost set it apart from common plants, marking it as a court poison, accessible only to those with means. The shimmering liquid metal that fascinated the ancients here becomes, once again, what it has always been: a poison.

The subject in depth

Mercury is the only metal that is liquid at room temperature, which earned it its old name of quicksilver, “living silver” [Wikipedia] . This shifting, shining appearance fed its magical and medical reputation for centuries. But in every one of its forms, mercury is a poison. As a heavy metal, it behaves like lead and arsenic: it accumulates and disrupts the function of many proteins in the body.

Droplet of liquid mercury and diagram of mercury accumulation in the body
Mercury builds up

Its toxicity depends on its form. Liquid mercury that is swallowed is largely eliminated without being absorbed, which for a long time falsely suggested it was harmless. Its vapors, however, released as soon as it is heated, are highly toxic to the lungs and brain. And when it combines with other elements, as in cinnabar, its red ore, or as organic compounds produced by bacteria in water, it becomes even more dangerous [Wikipedia] .

The effects of poisoning, called mercurialism, mainly strike two organs

[Wikipedia] . First the nervous system: tremors, memory problems, irritability, changes in mood and behavior, sometimes even delirium. Then the kidneys, which mercury damages over the long term. As with other heavy metals, poisoning is often chronic and insidious, because mercury is eliminated very slowly and builds up with each exposure.

Mercury thus completes the trio of heavy metals featured in the story, alongside the lead in white makeup and the arsenic in orpiment. Three shining, useful metals, three slow poisons, illustrating the same lesson: the beauty or usefulness of a material says nothing about its safety.

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