If you pour salt on a slug it will kill them within 10 to 30 minutes depending on how much salt you pour on the slug.
That's a good way to get rid of slugs in your yard or home is to pour salt on their body and it will surely kill them and get rid of them.
A lugs skin is moist and the salt will dry out the moisture from the slugs skin and without that moisture on the slugs skin the slug cannot survive.
When the salt is poured on the slugs moist skin a strong brine quickly forms and the process of osmosis then begins and then water is drawn from a weak solution and when the slug loses that moisture they become dehydrated.
When the slug dehydrates as a result of the salt on their skin the slug dies a lingering death by dehydration.