The Mad Hatter is perhaps one of the most memorable characters in Alice's Adventures in Wonderland. The book has been around since the mid 1800s, and the scene that takes place at the mad tea-party (which introduced the hatter and included other characters such as the March Hare and the Door Mouse) is one of the things that everyone remembers about the story. However, what some readers might now know is the idea of a mad hatter wasn't new at the time the book came out. It was, in fact, a pretty common piece of accepted wisdom that hatters went mad, and that was simply how the world worked.
They did, and it was, but there was a very specific method to this madness.
Why Did Hatters Go Mad?
During the Victorian Era (which is almost congruent with the hey day of the Wild West and the Civil War, for those paying attention) felt hats became quite popular. Bowlers, top hats, and other fine felts were a fashion requirement if one was going to be accepted in normal society; men wore hats, and that's the way it was. As such there was an entire industry dedicated to producing hats from beaver fur, as well as from lower quality rabbit fur. Mercury dust was brushed over rabbit hide during the tanning process, which was a cheap way to make the hide easier to work with. While we now know that mercury is a poisonous heavy metal, and that exposure to it over time is extremely hazardous if you don't wear proper safety equipment, Victorians were the kind of people who saw nothing wrong with putting a heavy dose of cocaine in their cough syrups. Due to lack of knowledge, and non-existent safety precautions, those who made hats were exposed to a lot of mercury. It was in the fur, in the glue, in the hat bands, and pretty much everything else a haberdasher worked with on a daily basis.
If you absorb a great deal of mercury into your system you will begin displaying symptoms like jerkiness and twitching, loosening of teeth, loss of coordination, slurred speech, loss of memory, mood swings, depression and anxiety. These symptoms, often referred to as Mad Hatter's disease or Hatter's Shakes, were sometimes confused with schizophrenia (fun fact; schizophrenia, in addition to the symptoms of Hatter's Shakes, also includes things like blank affect, delusions and other problems. This often makes communicating with a schizophrenic problematic). Given that hatters would breathe in mercury dust, lick hat bands, and handle mercury-treated felts without gloves or any other type of safety equipment, it's no wonder that the most skilled hatters tended to go more than a little mad.