1. Soften the gelatin in the cold water, then dissolve it by setting the pan in a pan of hot water and stirring. Let it cool.
2. Beat the egg yolks with 1/4 cup of the sugar until foamy. Stir in the cooled gelatin and the vanilla.
3. Whip the egg whites stiff, add the salt then slowly beat in the remaining 1/4 cup of sugar.
4. Whip the cream or evaporated milk stiff. Combine the cream and egg whites and fold into the egg yolk mixture.
5. Pour into 4 or 5 dessert glasses. Chill until firm.