In small bowl of electric mixer beat egg whites at highest speed until foamy. Add salt and cream of tartar, then sugar gradually, beating continuously until thick and glossy, 8 to 10 minutes in all. Line cookie sheet with brown paper or foil. For individual shells, divide meringue mixture evenly into piles, set well apart. With the back of a spoon, form a shell from each pile of meringue, smoothing the center and piling up the sides. For a large pie, shape all meringue into one shell or pile into buttered pie pan. Place in preheated oven. Immediately turn off heat. Leave shells in oven over night, or until they completely dry out (3 hours or more). Remove shells from oven and lift them carefully from the paper. Cool. Fill as desired with fresh fruit, ice cream, French Chocolate Creme, etc. Note: Meringues may also be baked in an oven set at 275 degrees F. for one hour, or until completely dry. If served immediately, shells are crisp. They become soft when filled and refrigerated.