Why does salt kill snails
Because it dries them out. Much like grapes in the sun
Snails' skin is made of mucous membrane. When you put salt on it, the salt draws the liquid out of the membrane and then kills the snail.
It is called exosmosis. The cells lose their water and get dried up. It is the opposite of what happens when your body swells up due to too much salt intake.If you are interested read more on Wikipedia http://en.wiktionary.org/wiki/exosmosis.
salt basically just dries them up like when you use a hairdrier to get the water out of your hair, but, in this case your killing the snail
dries up the slime
It could sting them