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Vinegar Biscuits

3/4 cup milk
1/4 cup cider vinegar
1 3/4 cups flour
1 1/2 teaspoons baking soda
1 teaspoon cream of tartar
3/4 teaspoon salt
3 tablespoons butter -- melted
1/4 cup flour

Mix together milk and vinegar. Sift together 1 3/4 cup flour, baking soda, cream of tartar, and salt. Add to milk mixture. Mix. Add butter. Beat 50 strokes. Place dough on lightly floured board. Knead in remaining 1/4 cup flour. Pat dough 1/2" thick. Cut into 2 3/4" rounds. Fold each round in half and press lightly. Place on greased baking sheet. Bake at 450 degrees for 10 minutes. Reduce heat to 400 degress; bake until light brown - about 8-10 minutes. Makes 8 biscuits.