Xylene sucks in that it will burn you without being lit off. Same with Toluene.. and it only takes seconds of exposure, usually before you can get to a wash station.
I used to carry small amounts of denatured alcohol with me when working with Xylol or Toluene, in case I got it on my clothes or hands, I could easily flush it quickly with Dn-A, which is basically harmless. It will dry your skin out a bit though, and it feels COLD when you touch it, even if it's hot. Mostly b/c it evaporates so quickly, like acetone.
BTW - If you don't already know, Xylene is a brand/product name, Xylol is the chemical name. They're used interchangeably.
Another chemical that I've tested to no avail (in a lawnmower) is MEK. Methyl Ethyl Ketone. [key-tone] (obviously, a member of the Ketone [kuh-toe-knee] crime family.
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The lawnmower had an issue with pinging after being rebuilt, due to use of incorrect parts. I tested MEK in it (free to me at the time) to see if it would solve the pinging issue. No such luck. It ran fine though, you just couldn't use WOT on it, as it was basically rebuilt as a higher compression version of itself. (Yep, that was mibad.)