In Anne McCaffrey’s series 'The Dragonriders of Pern', she describes her dragons chewing on rocks containing phosphinea chemical made of one phosphorus atom and three hydrogen atoms. In gas form, phosphine is very flammable and explodes on contact with oxygen.

Phosphine is under the category of pyrophoric chemicals, and is produced by heating phosphorus in an aqueous solution of potassium carbonate.

During the Great Wars that ravaged my Known World, the existence of dragons came to an end. A breakthrough for nations without the expensive dragonfire resistant armoury of the Northerners, and a blow to the economy of the latter.

But, those who had coexisted with the dragons (Westerners) were developing an imitation of dragon fire. These alchemists had created three possible imitations.

1. Red Fire or Bloodfire when red, Brimstone when black.

Formed by a pyrophoric sulphide - Mercury sulphide (Cinnabar). Produced by reaction of mercury (II) chloride with hydrogen sulphide. Smoke from fire contains poisonous mercury vapor and irritating sulfur dioxide gas; insoluble in water as a solid.

Extinguishing Agents: Water, foam, sand

2. Acid Sulphur

Works on bases of highly dehydrative ability of sulphuric acid, as it is known to absorb water from the air.

Two formations:

A. Formed by reaction of concentrated sulphuric acid, potassium permanganate and acetone (as a flammable agent).

B. Formed by reaction of sulphuric acid with water, in the presence of a flammable material (wood, oil, paper).

Not extinguished by water.

3. Dragon's Breath

Formed by reaction of phosphine with oxygen, in the presence of trace diphosphane. Can be extinguished with water, but not whilst being bombarded with phosphine.

Firstly, how exactly do my Western alchemists store these dangerous chemicals and gases, without corroding the containers (feasibility of mining and production as time period concurs with the age of alchemy in real life)?

Secondly, can fire siphons be used as propellants for these incendiary formations?

Important to note: The West in my Known World is not so dissimilar from the Middle East and North Africa.

  • $\begingroup$ Once again, cite your sources. $\endgroup$
    – L.Dutch
    Dec 1, 2019 at 13:35
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    $\begingroup$ Provide a link, like it is custom on the internet. Just stating (Wikipedia) doesn't bring anywhere $\endgroup$
    – L.Dutch
    Dec 1, 2019 at 13:47
  • $\begingroup$ Thank you, that's much better. $\endgroup$
    – user70311
    Dec 1, 2019 at 13:50
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    $\begingroup$ I've made a few edits to improve readability and applicability of tags. If you disagree, feel free to roll them back. $\endgroup$
    – Frostfyre
    Dec 2, 2019 at 13:55
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    $\begingroup$ Teleportation and tactics were required for McCaffrey's dragons to accomplish their task, and deaths were expected anyway. Flamethrower-like fuels are so dangerous, unreliable, and likely to destroy their containers and users, that McCaffrey literally gave her dragons teleportation to minimize the strenuous and time-consuming activity of flying to meet the Thread. $\endgroup$ Dec 3, 2019 at 0:49

2 Answers 2


TL;DR: apart from the sulphuric acid-based recipe, only use any of these things if you have a) a death wish and b) plenty of expendable fanatics who don't mind dying horribly in your service.

The acid-based recipe looks merely impractical for use in a flamethrower rather than some sort of boiling toxin bomb.

The problem here is not so much the storage of the materials (glass is readily available, if somewhat delicate) but their use as flamethrowers. The fuels are very dangerous to handle and, in two of the three cases, exceedingly toxic. You've also got a lot of gas-phase ingredients, which limits the range of your weapon (think "large flame" rather than "giant spray of burning liquid falling on your enemies") and as they will be low density you'll either have real problems carrying enough with you, or you'll have to produce them in quantity in situ and producing large quantities of reasonably pure and highly toxic gas with primitive chemical processes and pre-industrial equipment sounds like a disaster waiting to happen, and not for your enemies.

You won't be able to spray this stuff out of hand siphons... the operators will probably just kill themselves. Out of larger devices... well, maybe. The descriptions of the ship-mounted Greek fire siphons used by the Byzantines sound like they might be adaptable to your needs, but the chances of poisoning yourself whilst operating it is extremely high. Spraying around concentrated acid also sounds like a recipe for disaster... I'm not sure how practical it is to plate your ship in lead, but you'll end up with plenty of acid spray which is bad news for everyone.

All of your suggestions seem inferior to Greek fire. They might be redeemable if you can use solid or liquid-phase ingredients in bombs and grenades rather than playing with flamethrowers, but the aside from the acid option the other two recipes are probably too toxic to use on any battlefield where you value your own troops, or the land you're fighting on or near.

Red Fire or Bloodfire when red, Brimstone when black.

The mercury (II) chloride is deeply unpleasantly toxic and corrosive all by itself, and it is a solid at reasonable temperatures. You're proposing to mix it with hydrogen sulphide, which is also quite unpleasantly toxic and either has to be created on-site in great quantities or stored as a gas which will seriously limit the amount of fuel you can carry.

The people preparing your fuel will have a very brief life expectancy, I suspect, as will the people operating your primitive incendiary toxin squirter. I wouldn't necessarily want to be any of the people involved in shipping the chemicals around either. Or be nearby the weapon when it was used.

Acid Sulphur

You can store the acid in a glass carbouy; it was done that way for a fair chunk of history. Lead could work as temporary protection against spray and splash, being a conveniently mouldable and replaceable layer. I'm not sure how you could trivially mix and pump the ingredients together though... you're not going to be making a glass piston, and anything else is going to dissolve over time (except maybe gold, but seriously, are you going to make gold flamethrowers?). The acetone is not too difficult to transport, though of course the vapours are unhealthy and explosive. The permanganate is a solid, and will react readily with either of the other two ingredients so you can't pre-dissolve it, and you can't mix the two liquid-phase ingredients ahead of time either.

Getting everything to combine nicely and shoot out under pressure sounds like a bit of an engineering nightmare, given the technology level you're thinking of.

Dragon's Breath

Phosphine is a gas at the sort of temperatures you'll be able to create, and it is hideously toxic to boot. Pumping it without exposing it to oxygen sounds like a tricky job but not impossible. The problem is that when you squirt it out it'll produce a big frightening jet of fire but in the absence of a sticky liquid fuel that will continue to burn afterwards it won't be a particularly effective flamethrower. The fumes are corrosive and irritating which is risky to both the target and the shooter of the fire.

As it is a gas phase fuel, density will be low and so you won't be able to shoot it far or for very long before you run dry.

  • $\begingroup$ Why did you compare my formations to Greek Fire? 'Primitive incendiary toxin squirter' what is this please? I made no mention of any toxin. $\endgroup$
    – user70311
    Dec 1, 2019 at 14:10
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    $\begingroup$ @ChagatNahn because it was a known, working and highly effective flame-based weapon and one worth copying because it isn't a toxic hellstew. Fired from siphons and grenades, suitable for naval and land warfare. Probably doesn't need complex chemical processes to synthesise. What's not to like? $\endgroup$ Dec 1, 2019 at 14:12
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    $\begingroup$ @ChagatNahn what I would suggest you do is that you simply state that you're using an alchemical process to produce jets of flame. Don't say what the ingredients are or process is. Maybe not even the flame colour (though that's harder to elide). Conserve your detail for where its needed. Adding spurious technical details only gives you opportunities to be wrong... as you can see, its really hard to firmly base fantastic effects in reality. Just state that you're using chemical fire, and describe it in some way that doesn't sound like greek fire, and leave it at that. $\endgroup$ Dec 1, 2019 at 14:17
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    $\begingroup$ 'what I woudl suggest you do is that you simply state that you're using an alchemical process to produce jets of flame. Don't say what the ingredients are.' So no actual processes, just that alchemists are doing what they do? $\endgroup$
    – user70311
    Dec 1, 2019 at 14:19
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    $\begingroup$ @ChagatNahn yep. Ancient flame weapons clearly existed, alchemists existed, you can combine the two as you see fit. Just don't go into detail and you'll be absolutely fine. $\endgroup$ Dec 1, 2019 at 14:22


Back many years ago, I watched a cartoon film explaining how dragons make fire. A safer method exists without using posphine or anything related to Posphorus.

The dragons chew limestone. It reacts with the stomach acid and releases hydrogen. The hydrogen is released through burping. The dragon has an electric pulse generator organ similar to that of an electric eel, called "Thor's finger". It generates a spark which ignites the hydrogen. The hydrogen was said to increase lift but that is not sufficient so let's ignore it and rely solely on wings.

Few notes:

1) posphine is a gas, not a solid. It is unlikely to be found in rock, and I think posphates are way scarcer than limestone.

2) to avoid backfire explosions, the outcoming hydrogen should contain no air whatsoever, or the whole belly would explode.

  • $\begingroup$ Belly, as in the belly of a dragon? I am not exactly looking for this kind of answer. Carefully read the bottom part of the question's body. There are no dragons in my world :) $\endgroup$
    – user70311
    Dec 1, 2019 at 18:06
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    $\begingroup$ The Flight Of Dragons was the film. I thought the electrical bit was "Thor's honeycomb", but it turns out that we're both wrong and that it is "Thor's Thimble". So now we all know. $\endgroup$ Dec 1, 2019 at 18:44

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