# Can a liquid mercury pistol flamethrower exist?

The Cold War just got a whole lot hotter.

Ordinary 20th century flamethrowers are, let's admit it, huge. Covert operations, especially in urban settings, would not stay covert for long, if our custom-fitted-suit-and-tie hero decided to apply a little fiery pressure for the mission at hand. Luckily, I've come up with a solution.

Imagine a pistol or rifle made of a really thermally resistant material, which, instead of bullets, uses a grip-located reserve of boiling-point (~400° C) mercury as ammunition, which is sprayed in the target's direction.

One could argue this weapon too cruel and unusual for ordinary engagements, but I could see it being useful against heavily armoured enemy personnel.

Is such a weapon manufacturable with Cold War technological levels and would it, indeed, be effective against armoured opponents?

• Soooo... a pistol that only has one shot, that's a lot worse at killing people than the normal kind, that exposures the operator to neurotoxic vapours? Oh oh, and requires a continuous power supply to keep the ammunition warm. I'm not sure if cold-war era marketing technology would have been able to sell that, to be honest. – Starfish Prime Dec 5 '19 at 15:52
• Not to mention that it'll dissolve the non iron metallic parts of the gun – nzaman Dec 5 '19 at 15:55
• covert operations with a flamethrower huh? – BKlassen Dec 5 '19 at 16:02
• What is your main goal? To create a pocket sized flamethrower or to take out heavily armored personnel? Depleted uranium shells would probably be better for armor piercing purposes, and I imagine you'd be able to come up with two chemicals that could be mixed together on contact to create a projectile that burns on contact-- what about something like a paintball gun but the pellets are filled with napalm or something else sticky and flammable mixed with an oxidizing agent so that it ignites as soon as the pellet breaks? – Dugan Dec 5 '19 at 16:13
• @IvanT. I would try with Oxygen difluoride if you want to try to burn an heavy armor with an hot toxic gas. – Stefano Balzarotti Dec 5 '19 at 17:18

The absolute density (how much a given volume of the substance weighs) of mercury is 13593 kilograms per cubic meter. This can also be stated as 13.56 grams per cubic centimeter (by definition, the density of a substance in $$kg/m^3$$ is 1000 times the density in $$g/cm^3$$)

Source

If bursting flames in a city is not smart, even not smarter is loading your infantry with such a heavy metal: 1 liter of mercury weights 13.56 kg.

Apart from being heavy, mercury has the property of not wetting most of the surfaces, so this hot mass you are firing at your enemy will simply bounce off like water on a oily surface transferring little to no heat to the target.

Moreover, to propel mercury at a fair distance, considered its density, you need adequate machinery, which again has to be carried by the infantry.

No matter if it is feasible or not, it is not a good idea.

• Ooh, good point about the wetting; it'd be a terrible flamethrower-alternative for that alone. – Starfish Prime Dec 5 '19 at 16:29
• Yes not a good idea - mercury condensing everywhere – Slarty Dec 5 '19 at 19:36

Mercury boiling point is 356,7°C so it would be mercury vapour spray. And it would be a toxic weapon, it would be totally inefective against any armor.

But the atmosphere will be toxic and unbreathable, build an efective gas mask will be a bit hard due to the temperature.

• Most armour isn't sealed, so being bathed in hot, dense vapour will probably still be an unpleasant experience. But, y'know, not necessarily as unpleasant as being shot with armour-piercing bullets. – Starfish Prime Dec 5 '19 at 16:30
• @StarfishPrime It'll cause the victim neurological problems in a few years, so there's that... – nzaman Dec 5 '19 at 17:06
• @nzaman hot mercury vapour is going to form some... interesting products with stuff it lands on (eg. your skin or clothes). There are some forms of mercury that are much more readily bioavailable than the plain metallic kind, and can kill you an awful lot more quickly... months rather than years. – Starfish Prime Dec 5 '19 at 17:10
• @StarfishPrime Pretty sure you won't have to wait months when you're aerosoling your immediate surroundings with vaporized metal. – Stephan Dec 5 '19 at 18:17
• @Stephan its a small quantity of hot vapour. I suppose you could use it in a confined space, but that suggests there wasn't much brain to damage in the first place. – Starfish Prime Dec 5 '19 at 18:41