Dissolve gelatine in half a cupful of warm water.
Grate the rind from 2 of the lemons.
Separate the whites from the yolks of the eggs and beat the yolks with the sugar until creamy.
An electric beater helps here.
Add the grated rind and the juice of all 3 lemons gradually.
Now stir in the gelatine and strain all into a clean bowl.
Beat the egg whites until stiff, and fold into the mixture.
Transfer to a souffle dish and chill well before serving.