The sharp edges of the remains cut the slugs and snails. DE is sold in garden centers. Be careful that you don't inhale the dust. You'll need to reapply after rains. Crushed eggshells also help.
Some people like to use saucers of beer to attract the snails.
Or grapefruit rinds. Snails and slugs like fermenting materials. Dispose of the pests after they've fallen in. Persistence is the answer in trying to control snails. Wet weather, of course, increases the problem, and at such times, gardeners often use one of the commercial slug and snail baits.