If a country could produce compounds magically within a foot of them, given that the necessary atoms/elements are already there (could convert water to hydrogen peroxide, coal to diamond, Salt and water to Lye and HCl, etc.) but cannot produce compounds unless the element is already present (cannot produce radioactive elements, etc.), what would be the easiest way for them to severely damage civilization relatively quickly (not including the time it would take to stockpile the chemical)? Note, they cannot use explosions or radioactive fallout. This country has an extensive knowledge of chemistry, but it is in a fantasy setting.

  • $\begingroup$ How big is the civilization and how quickly to damage it? $\endgroup$
    – bowlturner
    Nov 20, 2015 at 20:23
  • $\begingroup$ The country in question has a population of about 2.5 million, and the world in total has a population of about 25 million. The stockpiling of the chemical can take up to a few hundred years, but once the actual process starts, it needs to be completed or irreversible within a few months. $\endgroup$
    – Maeta
    Nov 20, 2015 at 20:26
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    $\begingroup$ You don't mean decimate literally do you? As in kill one in ten. $\endgroup$
    – Samuel
    Nov 20, 2015 at 20:37
  • $\begingroup$ Why can't they use explosions? That's an unusual limitation for a mage that can do extraordinary things! Also, is conservation of energy a consideration for your mages? $\endgroup$
    – Cort Ammon
    Nov 20, 2015 at 21:35
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    $\begingroup$ Do you mean destroy life (title) or destroy civilization (text)? There is a difference, you know. $\endgroup$ Nov 21, 2015 at 0:23

8 Answers 8


Dimethylmercury (CH3)2Hg is a very nasty compound. It is easy to make even without magic. Long persistence i.e., generally stable compound. Low concentration required to kill (1 or 2 drops are fatal). Easily penetrates skin as well as common gloves. Liquid at nearly all environmental conditions, it has a high vapor pressure so even the fumes can be dangerous.

It is basically unused now because it is so toxic.

Possible downsides, it will migrate into the ocean poisoning it too and since it bio-accumulates the fish will be toxic. Easy to kill yourself if you mishandle.

Just looked up the LD50, for a average male, 4 mg is enough to kill an normal adult male 50% of the time. 4 mg is about 9 millionths of a pound.

There are poisons that have a much lower LD50 dosage level, but this is my favorite because it is so invasive and persistent once released.

Aquisition: Based on the LD50, you don't need very much mercury. It would be very easy to acquire enough mercury. Minimal cost to produce

Distribution: Since it is a liquid, your could spray it taking into account winds, crop dusting, drop it from balloons, etc. Spies could drop it into water supplies (colorless, only a weak odor). Don't know about taste, but I strongly suspect that if there was enough to taste you would be pretty thoroughly poisoned. You would not want to distribute via bombs as you would break down the molecule when it burns.

If you froze it and ground it into a very fine powder you could use it to seed clouds and let it fall as rain.

I.e., Most of the ways you could distribute other toxins. BTW, since you have magic, other distribution methods come to mind.

Mortar shells would be a great delivery system too.

One possible downside/upside I failed to mention is the low but still fatal dosage of (CH3)2Hg can take months or even longer to kill you. Downside if you are in a hurry, Upside if you consider all the effort the enemy expends in trying to help the victims. For marginal poisoning levels, by the time you exhibit obvious symptoms, it is probably too late to treat effectively.

If you know you have been poisoned by (CH3)2Hg, you can undergo chelation therapy which is effective is the dosage is not too high. UPDATE, after further reading, I am less sure that chelation would be effective.

I found this this cheery site that has videos on many poisons. (CH3)2Hg was one of them. UPDATE - the poison videos appear to have disappeared - too bad they were nice, replacement videos for Dimethyl Mercury, and the Pick You Poison channel, may interest you.

  • $\begingroup$ The ocean poisoning is fine. It can also destroy nature too, as long as it also decimates civilization. The problem with this is how would they get all that mercury, and how would they spread/distribute it? $\endgroup$
    – Maeta
    Nov 20, 2015 at 20:29
  • $\begingroup$ Updated answer to add distribution, etc. $\endgroup$ Nov 20, 2015 at 21:13
  • $\begingroup$ What's the half-life of dimethylmercury in the environment? $\endgroup$
    – lirtosiast
    Aug 12, 2016 at 19:38
  • $\begingroup$ @lirtosiast - I don't know of any studies of the half-life in the environment. In small quantities, it will disperse into the atmosphere fairly quickly due to its high vapor pressure. In large quantities, it would saturate the atmostphere. There would be some breakdown in the atmosphere due to UV cleaving the molecule, the C-Hg bond is not particularly strong. The Hg methyl group is still quite toxic, but nothing compared to the dimethlyl form. In short, sorry don't know the timeframe, would not really matter since everything would already be dead/dying long before it cleared. $\endgroup$ Aug 13, 2016 at 4:17
  • $\begingroup$ +1 on this. Dimethylmercury commands respect and fear with people that have to handle it. The infamous case of Karen Wetterhahn is... sobering, to say the least. $\endgroup$
    – MichaelK
    Aug 16, 2016 at 12:55


Dioxygen difluoride - $O_2F_2$

Dioxygen difluoride reacts with nearly every chemical it encounters – even ordinary ice – leading to its onomatopoeic nickname "FOOF" (a play on its chemical structure).

I don't know how effective this chemical would be for your stated purpose, however, it is nasty enough that I want to mention it and you deserve to know about it. From the blog Things I Won't Work with: Dioxygen Difluoride

The heater was warmed to approximately 700C. The heater block glowed a dull red color, observable with room lights turned off. The ballast tank was filled to 300 torr with oxygen, and fluorine was added until the total pressure was 901 torr. . .

And yes, what happens next is just what you think happens: you run a mixture of oxygen and fluorine through a 700-degree-heating block. “Oh, no you don’t,” is the common reaction of most chemists to that proposal, “. . .not unless I’m at least a mile away, two miles if I’m downwind.”

The resultant compound is affectionately called $FOOF$ in the chemical industry.

“Being a high energy oxidizer, dioxygen difluoride reacted vigorously with organic compounds, even at temperatures close to its melting point. It reacted instantaneously with solid ethyl alcohol, producing a blue flame and an explosion. When a drop of liquid $O_2F_2$ was added to liquid methane, cooled at 90°K., a white flame was produced instantaneously, which turned green upon further burning. When 0.2 (mL) of liquid $O_2F_2$ was added to 0.5 (mL) of liquid $CH_4$ at 90°K., a violent explosion occurred.”

And he’s just getting warmed up, if that’s the right phrase to use for something that detonates things at -180C (that’s -300 Fahrenheit, if you only have a kitchen thermometer). The great majority of Streng’s reactions have surely never been run again. The paper goes on to react $FOOF$ with everything else you wouldn’t react it with: ammonia (“vigorous”, this at 100K), water ice (explosion, natch), chlorine (“violent explosion”, so he added it more slowly the second time), red phosphorus (not good), bromine fluoride, chlorine trifluoride (say what?), perchloryl fluoride (!), tetrafluorohydrazine (how on Earth?! ...), and on, and on. If the paper weren’t laid out in complete grammatical sentences and published in JACS (Journel of the American Chemical Society), you’d swear it was the work of a violent lunatic.

The chemical was originally developed during WWII by German rocket scientists as a near perfect oxidizer in a rocket engine. It is in fact a much better oxidizer than pure Oxygen. In fact it works far too well and reacts with everything that it comes in contact with. The only way to store the stuff is mentioned below.

Both $FOOF$ and $ClF_3$:

can potentially go on to “burn” things that you would normally consider already burnt to hell and gone, and a practical consequence of that is that it’ll start roaring reactions with things like bricks and asbestos tile.

If the chemical escapes its container, it will spontaneously ignite with everything it comes in contact with and there is no way to stop the reaction.

There’s a report from the early 1950s (in this PDF) of a one-ton spill of the stuff. It burned its way through a foot of concrete floor and chewed up another meter of sand and gravel beneath, completing a day that I’m sure no one involved ever forgot. That process, I should add, would necessarily have been accompanied by copious amounts of horribly toxic and corrosive by-products: it’s bad enough when your reagent ignites wet sand, but the clouds of hot hydrofluoric acid are your special door prize if you’re foolhardy enough to hang around and watch the fireworks.

A "Hypergolic" chemical is one that immediately ignites when in the presence of the correct other chemical. Liquid fueled rockets in space use hypergolic fuels, for example Nitrogen Tetraoxide (aka NTO or $NO_4$) & Monomethyl Hydrazine (aka MMH or $CH_3\left(NH\right)NH_2$). This ensures that the rocket engine will always ignite when it is needed.

”It is, of course, extremely toxic, but that’s the least of the problem. It is hypergolic with every known fuel, and so rapidly hypergolic that no ignition delay has ever been measured. It is also hypergolic with such things as cloth, wood, and test engineers, not to mention asbestos, sand, and water-with which it reacts explosively. It can be kept in some of the ordinary structural metals-steel, copper, aluminium, etc.-because of the formation of a thin film of insoluble metal fluoride which protects the bulk of the metal, just as the invisible coat of oxide on aluminum keeps it from burning up in the atmosphere. If, however, this coat is melted or scrubbed off, and has no chance to reform, the operator is confronted with the problem of coping with a metal-fluorine fire. For dealing with this situation, I have always recommended a good pair of running shoes.”

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    $\begingroup$ I read this wonderful article you mentioned some time ago. The affection for the powerful chemistry of FOOF is clearly abundant in the article. $\endgroup$ Nov 21, 2015 at 21:31
  • $\begingroup$ I've got to find one on $ClF_3$ now. $\endgroup$
    – Jim2B
    Nov 21, 2015 at 21:57

You may be interested in botulinium toxin, that is basically the most toxic chemicals actually known. And its formula is$C_{6760}H_{10447}N_{1743}O_{2010}S_{32}$, so you only need very common elements to make it (however the exact formula is complicated and kept secret for obvious reasons). In fact, given the composition of air, you will find everything you need in it, except sulfur (which is quite easy to get).

The LD50 of the substance is estimated to be about 10 to 13 ng. Let assume you take 5 times this dose to be sure to kill everybody (50 ng), that mean you will need about $2.5 M \times 50$ ng $ = 125$ mg $= 0.125$ g of botullinium toxin to kill everybody. It is a ridiculously small amount.

Given all that, you will be able to create the lethal dose for the whole population anywhere if you carry with you a piece of sulfur, another of coal and water (for the hydrogen), and using oxygen and nitrogen present in air. So to disperse it you can just create it where you need it by sending "spies-sorcerers-chemists" to intoxicated food and water reserves.

  • 3
    $\begingroup$ It is truly fascinating to read a wikipedia document that has a section on "Bioterrorism" immediately followed by a section on "Brand names." $\endgroup$
    – Cort Ammon
    Nov 20, 2015 at 21:46
  • $\begingroup$ That's 10-13ng/kg of body mass. Also unless you can administer it directly to everyone, you're going to need a lot more of it. However, putting a few grams in water supplies will do a lot of damage, since the effects are fairly slow. $\endgroup$ Aug 16, 2016 at 10:48

My recommendation would be to train a bunch of your mages to turn chemicals in the human body quickly into a poisonous substance, changing water into H2O2 would be a simple and easy example, if they could do it quickly enough they could walk through crowded market places poisoning people as they walked through. Disguised as a local they won't be picked out right away as the culprit.

This will begin to cause panic. Anywhere that they can get within range of people of power, Governor's, princes, generals, even captains, cutting off the heads of reason and order, it won't take long to remove civil from civilization.


Why not explosions? Some of the best candidates for this alchemical ability are in the class of chemicals, so elegantly named by Dr Derek Lowe, "Things That Want To Revert To Elemental Nitrogen".

Probably the simplest one to cobble together is hydrazine, H4N2. It's used as rocket fuel, and is probably the nastiest chemical that is produced and transported on the scale of railroad tanker cars. Ideally, one nitrogen and two water vapor molecules make a hydrazine molecule and an O2 molecule. In practice the route to hydrazine is far trickier, because if you get enough oxygen anywhere near it the entire reaction will blow up in your face quite spectacularly. It's not truly pyrophoric (ignites spontaneously on contact with room temp air) but it's darn close.

Another extremely nasty chemical made from fairly common Earth elements is chlorine trifluoride. Both of these halogens are common in many types of rock, though it's more location-specific. Chlorine trifluoride is probably the most vigorous oxidizer that can be handled in industrial quantities. It's used on the semiconductor industry to clean silicon deposits from thin film etching equipment, which it no doubt excels at, because this reagent will literally set sand on fire. Wet sand is even worse; the chemical will readily dehydrogenate the water, forming an amalgam of foul gaseous hydrohalic and oxohalide acids.

The last one I'll mention is chloryl perchlorate, also known as perchloric acid anhydride. Made quite straightforwardly in your universe from compounds in salt water, it's a bit touchy, causing an explosive reaction with practically any organic compound. It also reacts exothermically with water to produce perchloric acid, which can touch off other explosive properties of the anhydride, the aqueous acid and its various salts.

Basically any of these, released in mass quantities into the natural ecosystem, will cause a very efficient deconstruction of said ecosystem. Hydrazine would be readily hypergolic (ignites on contact) with either of these oxidizers. In addition to their reactive and pyromaniac properties, all three get the NFPA's highest honors as poisons, mainly because these things will kill you before you can swallow. The only problem is they're indiscriminate; they don't care whether the organic tissue they're rending apart at the molecular level is friend or foe, and there's not much protection from them.


I can't help observing that there is no clear demarcation between chemical and life-form and that viii straddle the boundary. Given magic you could kill someone and start an epidemic by creating just one large molecule within an enemy. What molecule? The strand of RNA that a virus injects to cause a cell to start reproducing more viruses.

For maximum terror but no epidemic it would be rabies. For a pandemic probably smallpox.


Antibiotics, somministrate slight dose of antibiotics to all life forms, soon there will be lots of viruses and bacteria that are immune to antibiotics, diseases will start to spread everywhere and kill everything, note that this is partially already happening due to heavy usage of anti-fungine in coltures and to mass-somministration of antibiotics even if not needed. That requires a continued somministration for 1-2 years to everyone, if that is not factible in your world, you could instead use a Immunosoppressor.


Ocean poisoning with poison only consisting of C H N and O

Very similar to @Kolura's answer but just different chemical. Since you want to readily be able to produce the toxin I would limit the toxin to only include hydrogen, carbon, nitrogen and oxygen science they are available almost anywhere.

For example a neuro toxin like anatoxin-a also known as VFDF (Very Fast Death Factor), I am not kidding, consists of only these elements. Besides this specific one a range of these toxins is available.

Than just park your mages along a nice picturesque stream and turn the whole stream into this toxin. Keep it up long enough for total decimation of life.

On a side note if you want to do it more slowly, you can do it the way we do it today. Just make microplastic from polyolifins (only consisting of C and H) that are not biodegradable and wait for all ocean life and a better part of the land life to die if concentrations become high enough.


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