Potato Soup #2

4 medium-sized potatoes
1 quart milk
1 small onion
3 tablespoons fat
2 tablespoons flour
1 teaspoon salt
1/4 teaspoon celery salt
Dash of black pepper
2 teaspoons chopped parsley

Boil the potatoes in salted water. When soft, put through a ricer, slice the onion and scald the milk with the onion in it. Remove the onion. Add the milk to the potato. Melt the fat, add the flour, stir into the boiling soup, boil one minute. Sprinkle with the parsley.