2 c. packed light brown sugar
1/2 c. light corn syrup
1/2 lb. butter
1/4 tsp. cream of tartar
1 tsp. salt
1 tsp. baking soda
6 qts. freshly popped popcorn

In 2 1/2 quart saucepan combine brown sugar, corn syrup, butter, cream of tartar and salt. Heat to boiling, over medium-high heat, stirring constantly, boil rapidly to hard-boil stage, 260 degrees (about 5 minutes). Remove from heat. Stir in baking soda quickly but thoroughly and pour at once over popcorn in large roasting or baking pan. Stir gently until completely coated. Bake in oven at 200 degrees for 1 hour, stirring 3 times. Cool on waxed paper. Break apart and store in tightly covered container.