Mad as a hatter.

[vinrex7]

Can anyone tell me where this phrase came from? cheers in advance

[BigMac]

Short version:
This expression, dating from the early 1800s, alludes to exposure to the chemicals formerly used in making felt hats, which caused tremors and other nervous symptoms.

[Quizmonster]

Click here for the long version!

[rojash]

Medium version: the chemical was mercury

[em93]

i thought it was alice in wonderland :S