Add the salt to the water and bring to a boil in the inner cup of a double boiler.
Stir in the rolled oats.
Boil for 2-3 minutes, then set the inner cup in the outer cup of a double boiler which contains boiling water. Continue cooking for three hours or longer.
Strain the oatmeal and add hot milk to taste.
Barley gruel, cornmeal gruel, or rice gruel may be made by replacing the rolled oats with 1/3 cup pearl barley, 1/4 cup cornmeal, or 1/4 cup rice. For cornmeal or rice gruel, 1 hour of cooking time is sufficient, but barley may need 4-5 hours.