In a large saucepan combine sugar and gelatin.
Stir in evaporated milk.
Cook and stir over medium-low heat till mixture almost boils and sugar dissolves, then remove from the heat.
Stir together egg whites and egg.
Stir about 1 cup of the hot mixture into egg mixture; return all to the saucepan.
Cook and stir 2 minutes more, then add skim milk and vanilla.
Freeze the mixture in a 4- or 5-quart ice cream freezer according to the manufacturer's directions.