Herbicides and salt - another question of wonder (Oct/18/2004 )

I know i've been asking a lot of questions lately but ive been wondering all too much..

Before the advent of cheap toxic herbicides, people used to pour handfuls of salt on the soil around weeds to kill them. But why? How does this mechanism work for killing plants (since this is so old fashioned)

From what I remember of my plant physiology this system makes the soil water have a high ion content and as plants rely on osmosis (and some active transport) for uptake of water, if there is a higher content of ions in the soil than in the plant, water will move out of the plant rather than into it, casuing the plant to dehydrate and eventually die.

thankssss!!!