Mad As A Hatter

History:The Mad Hatter is a memorable character in Lewis Carroll’s Alice in Wonderland, but the expression is much older. It is thought to derive from the effect on felt workers of the mercury used in making felt hats; after some years many of them developed a tendency toward severe twitching. As early as 1837 Thomas Haliburton had the expression in The Clockmaker: “Sister Sal… walked out of the room, as mad as a hatter.”