Grandma's French Dressing II

1/4 cup sugar
1/2 teaspoon dry mustard
1/8 teaspoon black pepper
1/2 teaspoon salt
1/2 teaspoon Worcestershire sauce
1/2 cup ketchup
1/2 cup salad oil
1/4 cup white vinegar
1 small chopped onion
1/4 teaspoon celery salt (optional)