1. Preheat oven to 350°. Brush piecrust with beaten egg white. Bake 6 minutes. Remove from oven, and cool completely on a wire rack (about 30 minutes).
2. Beat 4 egg whites at high speed with an electric mixer until stiff peaks form.
3. Whisk together 4 egg yolks, sugar, and melted butter in a large bowl until blended. Stir in lemon juice. Fold in egg whites. Pour mixture into cooled piecrust, and place pie on a baking sheet.
4. Bake at 350° for 25 to 30 minutes or until set, shielding edges with aluminum foil after 20 minutes to prevent excessive browning. Remove from oven to wire rack, and cool completely (about 1 hour). Garnish, if desired.