Did the Mad Hatter Have Mercury Poisoning?
The Mad Hatter may be crazy, but he wasn't mercury poison crazy. Oh no. Mercury poisoning has symptoms get much worse.
He may have had only a "trace." Perhaps, "a small amount?" Perhaps just the regulated dose per Center For Decease Control.
Disclaimer: Mark Twain (1835-1910-To be continued) is unlicensed. His river pilot's license went delinquent in 1862. Caution advised. Daily Paul ☑