Spread popcorn in a lightly buttered roasting pan; bake at 250° while preparing syrup, about 10 minutes. Pour cinnamon candies into a 2-cup measuring cup; fill remaining space to the top with sugar. Place in a heavy saucepan; add butter, corn syrup and salt. Bring to a boil; boil 5 minutes. Remove from heat; carefully dtir in baking soda. Pour over warmed popcorn, stirring every 15 minutes. Remove from oven; let cool. Break into pieces; store in airtight container. Makes 6 quarts.