Remove all the grease from the top of the jelly, and wipe it off with a cloth wet in hot water, so every particle of grease will be removed. Stir into the cold jelly the beaten whites and the shells of three eggs (do not froth the egg). Put it on the fire, and continue to stir until it boils. Let it boil for five minutes; then strain it through a double cloth. If not perfectly clear, strain it a second time. Let the jelly drain through the cloth without pressure.