Where Does “Mad Hatter” Come From?
To understand the phrase “mad hatter” requires bringing some science into etymology. Today, scientists know that the element mercury is toxic. It can harm “the brain, heart, kidneys, lungs, and immune system of people of all ages,” according to the United States Environmental Protection Agency. The severity of mercury’s effects depends on the length, amount, and kind of exposure, in addition to the individual’s age and health. Mercury exposure causes a wide range of troubles, from mental health issues to hearing impairments to fatal respiratory failure. In summation: mercury is very bad for your health.
However, medieval Europeans were not privy to this information, so they used mercury in both medicine (which is ironic) and manufacturing. In the 18th and 19th centuries, workers continued to use mercury — specifically, mercurous nitrate — in the field of hat-making. Using this chemical compound, they would turn animal fur into felt to fashion their hats.
Through their exposure to mercury day after day, hatmakers inhaled a considerable amount of the toxic vapors. Over time, the poison took its toll mercilessly on the workers. From hallucinations to insomnia, the unfortunate hatmakers experienced almost the entirety of mercury poisoning’s wide array of detriments.
They suffered from trouble thinking or concentrating, a lack of patience, and memory loss. Hatmakers grappled with emotional instability and mood swings, including anxiety, irritability, and, oddly, became rather shy. Hatmakers also developed tremors, eventually coined as “hatters’ shakes.” (In Connecticut, these tremors were called “the Danbury shakes,” since Danbury was considered the leading center of hat-making.) On top of all this, they also dealt with issues with speech and movement, which became coarse and jerky.
Oblivious to mercury’s toxicity, doctors had no explanation for these deteriorations in hatmakers’ health. As a result, society came to the conclusion that hatmakers were simply crazy. No one made the connection between hatmakers’ illness to their use of mercury for decades; American hatmakers continued to work with mercury until the early 1940’s. Until then, society came to terms with the conclusion that hat-making somehow caused insanity. By 1837, people began commonly tossing around the phrase “mad as a hatter.” Less than thirty years later, the famous character Mad Hatter appeared in Lewis Carrol’s Alice in Wonderland.
Today, thankfully, hatmakers no longer work with mercury. Subsequently, hatmakers do not suffer from the ailments that accompany the poisonous vapors — in other words, they are no longer “mad.” Despite this, the phrase “mad hatter” continues to stick around. Filmmakers continue to make new versions of Lewis Caroll’s work, all featuring the beloved Mad Hatter. America even celebrates “Mad Hatter Day” every October 6th. In the typical fashion of an idiom, this phrase’s context no longer exists, but we continue to keep the expression alive.