Combine egg yolks, sugar, gelatin, water, lemon peel, lemon juice, and salt.

Cook over medium heat, stirring constantly, just until it boils.

Place pan in refrigerator, stirring occasionally until mixture mounds when dropped from a spoon.

In a separate bowl, beat egg whites and cream of tartar until frothy.

Beat in sugar one tablespoon at a time until stiff and glossy. Do not underbeat.

Fold in cooled lemon mixture, and then pile into pie shell. Chill several hours until set.