This can be used to show the forces exerted by atmospheric pressure. A light walled tinplate can, H260 x 75mm diameter, with an air-tight neck and screw cap. A small quantity of water in the can is boiled vigorously until steam occupies the space inside the can, at which point the top is screwed down tightly and the heat source removed. As the can cools down, atmospheric pressure is increasingly exerted until the can noisily collapses.