1. Start oven, set at 375° F., Moderate. Rub a 1 1/2-quart baking dish with butter or margarine.
2. Drain the turnips and slice them.
3. Arrange a layer of them in the bottom of the baking dish, sprinkle lightly with some of the salt and mace, then with a few crumbs. Dot with butter or margarine.
4. Heat the celery soup with the milk and pour some of the mixture over the turnips Repeat until all ingredients are used.
5. Bake 30 minutes.