“You keep using that word….”

(Or, you know you have degrees in chemistry and English when…)
So I was just going through the posts on my WordPress Reader and came across today’s–well, yesterday’s, since it’s after midnight–Daily Prompt. The post title was “Mad as a Hatter,” but the actual prompt was asking for posts about rage.
BZZZT. WRONG.
“Mad as a hatter” refers to a completely different definition of “mad”–insane. There used to be a high incidence of hatters going crazy, and while G. K. Chesterton once quipped that the cause was measuring the human head, it actually had a much more prosaic root. You see, once upon a time, the felt used for making hats was manufactured using significant levels of mercuric nitrate. Due to the processes by which hatmakers shaped the felt and blocked the hats, as well as the poor ventilation of their shops, they inhaled vaporized mercury on a regular basis… and one of the symptoms of mercury vapor inhalation is psychosis. As the Hazardous Substances Data Bank article puts it, “Subacute exposure has given rise to psychotic reactions characterized by delerium, hallucinations, and suicidal tendency.” So widespread and severe was the effect of this occupational hazard that it became a byword in English. The condition itself is known as mad hatter disease, but even people who weren’t victims of mercury poisoning yet displayed similarly erratic behavior were said to be “as mad as a hatter.”

And isn’t that a cheerful topic to bring up this close to Christmas…. 😐 Sorry, gang, will aim for something lighter later.