Glycerin is available in pharmacies and baking-supply stores. It keeps the icing soft a little longer and adds a slight sparkle.
Beat egg whites until stiff but not dry. Add sugar, lemon juice, and glycerin. Beat 1 minute. If icing is too thick, add water. If too thin, add more sugar.
Divide icing into smaller bowls. Tint with small amounts of paste or liquid food coloring; mix well for an even color.