By Simon Cotton, University of Birmingham

From the enticing aroma of the turkey in the oven to the “whoosh’” of the flames as the brandy-soaked pudding comes alight, Christmas is a wonderful time for the senses. But have you ever considered the science behind our best-loved festive traditions? Here is one of my seven food and flammable favourites: The others can be found on this website.

And what about the crackers you pull at the meal? How do they work? Some crackers use a chemical called silver fulminate. It is a very shock-sensitive substance, a cousin of chemicals such as lead azide, used in detonators.

As you know, a cracker contains two long, narrow strips of card. One is painted with a tiny amount of silver fulminate, while the other is coated with an abrasive – a sandpaper-like material. They are in contact with each other so that when the cracker is pulled, the two strips of card slide past each other and the friction from the abrasive detonates the silver fulminate. There is only a tiny amount – micrograms – of the silver fulminate: any more and the “crack” would be a “kaboom!”

This is part of an article originally published on The Conversation. Read the original article.