Unorthodox Fire Starting Devices

A fire plunger. Image courtesy eBay

Two gadgets for those who need to light a fire when camping or otherwise and want to show off (although a cigarette or gas lighter is perfectly adequate):

A plasma lighter produces an electrical arc between two electrodes using a high voltage, generated from a rechargeable battery. The temperature of an electrical arc can reach much 19,400 °C, so it can easily melt steel (arc welding) or light tinder for starting a fire.

A fire plunger or fire syringe is like a bicycle pump with a cylinder into which a small piece of tissue or rag is placed. To operate the device, a plunger is rapidly slammed into the cylinder and this compresses the air inside, rising its temperature by several hundred degrees. This is the same principle on which a diesel engine works—a gas increases in temperature when it's compressed. Once the tissue ignites, the embers can be used to ignite kindling.

Like most real-world examples, a fire plunger doesn't obey Boyle's Law, Charles's Law or Gay-Lussac's Law exclusively. All of these laws of thermodynamics require one variable—temperature, pressure or volume to be kept constant, while two of the other variables change. In a fire plunger, or when pumping a car tyre for that matter, pressure, volume and temperature all change at the same time.

Gay-Lussac's law may be the one you experienced as a child if you ever through a bottle or can into a fire and it exploded. The law states that at constant volume, pressure is proportional to temperature. 

A plasma lighter. Image courtesy eBay.