For an individual serving, cover two teaspoonfuls of granulated gelatin with four tablespoonfuls of cold water and let it soak a half hour; add a cupful of boiling water, four tablespoonfuls of sugar and the juice of a lemon; stand aside until it begins to congeal but is not quite stiff. Drop in the unbeaten white of one egg, stand the basin in a pan of cold water and beat continuously until the mixture is as white as snow. Turn at once into a small mold and stand away to harden. Put a half cupful of milk over the fire, add the yolk of the egg beaten with a tablespoonful of sugar, cook a minute, take from the fire, beat rapidly a few minutes with an egg-beater, and turn out to cool. Serve the pudding with a sauce poured around it.