Sodium hydroxide
And you were increidbly lucky, that stuff does horrific damage to eyes and to skin, although you were probably given pretty dilute stuff.

Glad you're not a twat any more! :P

EDIT: Just remembered, in our H&S induction when I started my PhD we were shown what was left of the labcoat and trousers belonging to a lab tech who had spilt molten pure sodium hydroxide down himself. He ended up naked under a safety shower, which was a pretty lucky escape considering. And to ease your guilt a little I meant what I said about you being given dilute stuff - teachers really won't give you stuff you can hurt yourself that badly with and they will try and make it sound more dangerous than it is to scare you into not doing what you did.
(Petite chien is going to do science to it, Tue 1 Feb 2011, 17:40, 4 replies)

We used to use 4M stuff a lot for cleaning chromatography resins in my PhD.
it's quite entertaining because it's massively exothermic going into solution. So, oooh, for instance, if you make up 10 litres of 4M NaOH the lazy way (put 10L glass duran with 9 L of water in it onto magnetic stirrer, throw in *calculates* 400g NaOH) it tends to sit round the bottom of the duran no matter how fast you are stirring. And get REALLY hot. And then, sometimes, fracture the glass slightly. So when the unsuspecting PhD student comes back half an hour later and picks up his 4M solution by the neck of the duran, the flat bottom of the duran stays where it is and 9 litres of brutally strong base hit you in the stomach and crotch. Mmmm, soapy balls.
( the mighty badger Aphrodite, on a bar stool, by your side, Tue 1 Feb 2011, 18:13, closed)

Wouldn't that be "just over 1M"?
400g NaOH = 10 moles.

10 Moles in 9 and a bit litres = approx 1.1 Molar?

But my school days are now a far-off land, so may be talking nonsense.
( Ghoti Fingers, Tue 1 Feb 2011, 18:41, closed)

You are correct
I do believe the mighty badger may have meant 1600g.
(Petite chien is going to do science to it, Tue 1 Feb 2011, 19:09, closed)

At least it wasn't Magic Acid.
www.rsc.org/chemistryworld/Issues/2007/September/ColumnBenchMonkey.asp
( The Mock TurtIe ™ --- Thinks you are a cunt, on, Tue 1 Feb 2011, 22:16, closed)

^ what she said.
You really don't want it in your eyes.
( Colonel Boris "...a desperate Buzzfeed imitation...", Tue 1 Feb 2011, 22:33, closed)

Caustic soda - just like Fight Club
I should have made the connection really.

If I ever met teenage me, I would punch him in the face. It would be highly cathartic and provide an entertainingly bizarre memory.
(leviticus no longer likes the cut of your gib on, Wed 2 Feb 2011, 12:19, closed)