I enjoyed your recent article about the psychiatric inspiration for Lewis Carroll but you didn't comment on the provenance of the term "Mad Hatter". It relates to the neuropsychiatric complications of mercury poisoning, in the 19th century hat industry (most prominently Luton) mercuric nitrate was extensively used in felt making. Over time this affected the central nervous system of workers causing shaking, confusion and emotional instability amongst other ghastly manifestations. Hence the phrase Mad as a Hatter and no doubt sufferers may well have ended up in institutional care.

Incidentally Luton retains this industrial link – its football team is locally known as the ‘Hatters’; fortunately there is no longer any need for a qualifying adjective although rival fans may dispute this!

I enjoyed your recent article about the psychiatric inspiration for Lewis Carroll but you didn't comment on the provenance of the term "Mad Hatter". It relates to the neuropsychiatric complications of mercury poisoning, in the 19th century hat industry (most prominently Luton) mercuric nitrate was extensively used in felt making. Over time this affected the central nervous system of workers causing shaking, confusion and emotional instability amongst other ghastly manifestations. Hence the phrase Mad as a Hatter and no doubt sufferers may well have ended up in institutional care.

Incidentally Luton retains this industrial link – its football team is locally known as the ‘Hatters’; fortunately there is no longer any need for a qualifying adjective although rival fans may dispute this!