Smoke rings from a toy gun don't do much more than entertain a child. But by giving them an electrical charge, a company called Battelle has discovered a way to make them more useful for firefighting and even crowd control.
Its new gun has a special cylinder on the end that creates vortex rings that leave the barrel at 90 miles per hour, and travel for more than 50 yards at a speed of at least 60 miles per hour. And by giving the particles that are emitted an electrical charge, they actually stick to their target on impact.
So firefighters could launch a charged vortex ring into a smoky room, which would cause the smoke particles to disperse and seek out the nearest grounded surface. Or, in a more disturbing application, riot police could fire rings of pepper spray from a distance, ensuring the painful payload would be delivered and would actually stick to the skin of the intended target. So the next time you see a mesmerising smoke ring coming towards you, I'd suggest looking away just in case.