To prepare live snails for cooking, remove the membrane, if any, over the shell opening. Soak the snails in enough water to cover them. (Add 1/2-cup salt or 1/4-cup vinegar for every 50 snails.) Mucus will turn the water white. Change the water several times during the 3- to 4-hour soaking. Rinse several times or under running water until no mucus remains. Put snails in cold water and bring to a boil. Boil about eight minutes, then drain and plunge the snails into cold water. Drain. With a needle or small fork, pick the snails out of their shells. Remove the intestine and cut off all black parts. (Some cooks also cut off the head, tail, and all "cartilage or gristle.") Prepare according to your recipe. An alternate method is: Wash the snails well in clear water. Drop into boiling salt water (to which you may add lemon juice and/or herbs), and cook--about 10-15 minutes--until you can easily remove the snails from their shells. Drain and rinse.