Granny Olson’s Caramel Popcorn

1 cup margarine or butter

2 cups brown sugar

1 teaspoon salt

1/2 cup corn syrup

1/2 teaspoon baking soda

1 teaspoon vanilla

6 quarts popped popcorn

Melt butter, stir in sugar, corn syrup, and salt boil about 10 minutes.  Remove from heat, stir in baking soda and vanilla.  Pour over popcorn.  Bake at 250° for 1 hour.  Stir every 15 minutes.