Filling for marshmallow cake
Dissolve five tablespoonfuls of gum arabic in a gill of cold water; then stir in a half-cupful of powdered sugar and boil all together until a little dropped in cold water can be rolled into a soft ball between the finger and thumb. Have ready-beaten the white of an egg and strain the syrup into this, beating the stiffened egg constantly as you do so. Flavor with vanilla and spread upon the cake layers with a knife dipped in boiling water.