Chocolate, Bedtime Teas, Edam Cheese

Jimmy Doherty tries to find out what the white powdery residue that can form on chocolate is with the aid of the world's biggest X-ray machine, which is 2.3km in circumference. In Belgium, Kate Quilton asks if any of the ingredients in bedtime teas can really help people to sleep, while Matt Tebbutt is in the Netherlands to discover if balls of Edam really were once used as emergency cannonballs. Last in the series.