Soak beans over night; drain. Cover with fresh water and the soda and boil, until skins break, but do not let beans become broken. Cut rind from salt pork and cut into six or eight pieces. To 1 cup of boiling water add the cayenne, salt, molasses, mustard and tomatoes. In bottom of bean pot place the onion and a piece of salt pork. Add beans. Pour over this the seasonings. Cover the beans with boiling water. Bake three hours covered. Uncover, put spinach to which has been added 1 teaspoon of salt, 1 tablespoon of vinegar, one-eighth teaspoon of pepper, on top. Bake 30 minutes and serve.
Foods That Will Win the War and How to Cook Them (1918).