Sorry, this should have been part of yesterday’s post.

I’ve always known that “mad as a hatter” was something to do with hatters, madness and chemicals but I wasn’t quite clear on the details. I’m currently reading The Elements of Murder (slowly, I admit, but it isn’t light reading) and the book has some interesting details.

I was going to stick a paragraph in about it, as it seemed appropriate and I had a suitably mad photograph. However, having the information and the need to write a post I thought I’d better find more information to fill it out.

This proved to be a mistake. “Mad as a Hatter”, according to some sources, has little to do with madness, and nothing at all to do with hatters.

This is a nuisance, to say the least. According to Wikipedia there are several possible sources for the expression, including the Anglo-Saxons who used the expression to mean venomous as a viper. There are other explanations too. I’m not happy with any of them, nor am I impressed by the references to early usage, without exact dates. However, this is a blog, I’m citing Wikipedia and I’m never going to be mistaken for an academic.  Can we just say “other explanations are available”, and I’ll talk about the one I want?

The Mad Hatter is supposed to be based on Theophilus Carter, an eccentric Oxford furniture dealer and reputed builder of an alarm clock bed exhibited at the Great Exhibition of 1851. When it was time to get up a clockwork motor engaged and tipped the sleeper into a tank of water. This seems a bit brutal even for stern Victorian early risers.

Unfortunately, though there were two alarm clock beds exhibited in 1851, neither of them was attributed to Carter in the catalogue. Nor, despite Carroll’s extensive diaries, is there any real evidence  that the Mad Hatter is based on Carter. It’s a shame, because it’s a good story.

There is, however, plenty of evidence for hatters exhibiting signs of madness.

The main material used in making hats was felt, which was made from the hair of rabbits and beavers, mixed with mercuric nitrate and repeatedly shaped, boiled and washed until it formed smooth cones of felt. This process released mercury vapour which, went inhaled, caused symptoms such as delirium, hallucinations, irritability, excitability, tremors and depression.

In many countries, including the UK, measures were taken to protect workers from exposure and by the end of the 20th century hatters were no longer suffering the effects of mercury poisoning. In the USA it persisted until 1941, being known as the “Danbury Shakes”, after the hat-making centre in Connecticut. Eventually the need for mercury in the war effort meant the use of alternative chemicals and the end of the Danbury Shakes.

Be that as it may, in the 1860s, when Carroll wrote about the Mad Hatter, mercury poisoning, was a major factor in the behaviour of hatters.