Interesting fact of the day: Why onions make you cry

Some of the stuff in onions contains sulphur. When you cut an onion, the cells which contain the sulphur are broken apart, triggering enzymes which release the sulphur as a gas.

When this suplhur reaches your eye, it reacts with the water in there to make sulphuric acid.

Which stings. Lots. In turn, this makes you cry - turning you into a big sissy.

The only proper solutions are:

1) Chill the onion - this can prevent the enzymes from going off.
2) Use a sharp knife - this can reduce the amount of damage to the cells.
3) Have good ventilation.

Ah, the wonders of Open University freebies.