Put half a pound of powdered sugar into a basin; grate in the rind of two fine lemons, add four egg whites, and mix well with a wire-whip for two minutes, then add a pint of cold milk, stirring again for one minute. Place the basin on the hot stove, stir briskly with the whip, and take it off when coming to a boil, put it on the table, and pour in a pint of sweet cream, mixing well for two minutes. Let it get cool during half an hour, then strain through a fine sieve into a freezer, and finish precisely the same as for vanilla ice-cream (No. 68).