Sponge Candy 1 cup granulated sugar 1 cup dark corn syrup 1 tablespoon cider vinegar 1 tablespoon baking soda Heat sugar, corn syrup and vinegar to boiling in a 2-quart saucepan over medium heat, stirring constantly, until sugar is dissolved. Boil without stirring, to 300 degrees F on candy thermometer (hard ball stage). Remove from heat. Quickly stir in baking soda thoroughly. Pour mixture into ungreased 13 x 9-inch pan. Do not spread! Cool, then break into pieces. Candy can now be dipped in chocolate coating if desired.