Although it may seem a fire breather is really blowing fire out of his mouth, that’s not really happening. Learn the science behind fire breathing.
Fire “breathing” is really just burning a fuel by blowing it over a flame. In order to burn, a fuel has to mix with oxygen in the air. Some fuels need a lot of oxygen to ignite and some don’t. Highly combustible fuel would be too dangerous to spit out, because the flame could jump back into the fire breather’s mouth, despite the scarcity of oxygen inside the mouth. The ideal fuel to spit out should require a lot of oxygen to ignite. Therefore, the fire breather uses a less combustible fuel, but he sprays the fuel into a fine mist. This gives the fuel plenty of opportunity to mix with oxygen to allow a fire.