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 up to 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, enough to ignite the tissue inside. 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 threw 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.