During World War II, different nations had to use all sorts of creativity to create weapons that could effectively give them an advantage in the war. There were various types of artillery, vehicles, gas weapons. Anything that will get the job done. It’s interesting to know that there was one weapon that the Nazis decided not to use, or at least stopped trying to, and they had all the reasons why. It’s with the chemical called Substance N.


In 1930, Ruff and Krug in Germany discovered a new compound. They discovered a very potent substance that boils at room temperature and burns at 2,400 degrees Celcius. If it decomposed, it turned into a hydrofluoric and hydrochloric acid, usually in the form of steam. Chlorine trifluoride also explodes when mixed with water. It would also ignite upon contact with almost anything, and by that, we mean anything, even those that were not usually flammable— glass, sand, even asbestos. And since it reacted explosively with water, normal fire fighting methods would only make things worse.

Chlorine trifluoride as A Potential Weapon

Chlorine trifluoride. Photo from Fact Republic

Germany ignored this substance because it was too volatile until a few years later. It garnered attention as a possible weapon. With everything that it does and can do, the Germans imagined the effect a shower would have on enemy soldiers and equipment. They would literally explode in flames in a cloud of hydrofluoric acid and hydrochloric acid. They decided to call it, unappealingly, Substance N. (I’d personally choose something like ‘Chemical X’ if it were me.)

They moved further research and production to Falkenhagen Industrial Complex. Here, they tried to, for many years, produce enough of this material to actually weaponize it. The original plan was to produce 50 tons of Substance N each month and use it to melt concrete, metal and flesh, destroying buildings and fortifications, ships, planes, tanks and set enemy troops on fire. Substance N was one of those Wonder Weapons the Nazis worked on, and this stuff would burn everything it came in contact with. I could almost hear the mad scientist laugh that came along with a plan worthy of Hydra from the Captain America comics.

However, they ended up producing only about 30 tons of it until the end of the war. Substance N was so unstable that they couldn’t figure out how to employ it as a weapon. When they tried to put it in a flamethrower, it burned all its components that were not steel. They were working on artillery shells containing Substance N, but this had its own problems of storage and use. It proved just about impossible to safely handle or store. You could store it in sealed containers of steel, copper, or iron as long as it was carefully treated first with fluorine gas to form a non-reactive layer inside the container. If it wasn’t done just right or if the slightest bit of moisture remained in the tank…Ka-Boom!! The Nazis would’ve, for sure, used it as a weapon to annihilate their adversaries had they developed a safe means of utilizing it. Perhaps we should be thankful they didn’t?

NASA Tried Too

NASA rocket thrusters.

The strong oxidizing properties of Substance N made NASA look into it as potential rocket fuel because of its incredible oxidation properties. It needed no oxygen to burn fiercely. As you may know, oxidizing agents are vital in rocket fuel to create propellant force. However, in the 1950s, one of the tanks containing Chlorine trifluoride ruptured and spilled two tons of the chemical on a concrete floor. It miraculously didn’t explode, but it burned through eleven inches of solid concrete and continued to burn down through the nearly three feet of gravel beneath it. Needless to say, NASA decided that it was more dangerous to deal with than any benefit it might offer in terms of being a rocket fuel. Given that so many NASA scientists at the beginning of the space program where Germans bought back after the defeat of the Nazis, you wonder if one had worked on the program during the war.

To summarize the whole experience of trying to work with Chlorine trifluoride, here’s what NASA Chemist John Drury Clark had to say, “For dealing with this situation, I have always recommended a good pair of running shoes.”