Westend61 GmbH/Alamy
Why is it that, when spraying an aerosol can of deodorant, it suddenly becomes very cold when it runs out?
David Jackson
Gosport, Hampshire, UK
Many aerosols use a mixture of the hydrocarbon gases propane and butane as their propellant – the material that drives the contents out. This is because these gases are liquids at a couple of atmospheres of pressure, which is easily contained in a metal can.
Anyone who has handled a transparent gas lighter will have seen this, where the butane fuel is visible as a liquid with gas above it. The same is true in the…
