Nearly 1,200 years ago, ninth-century Chinese alchemists were searching for an elixir of life—a potion that would allow whomever drank it to live far longer than the medical science of the time could accomplish—when they happened upon a mixture of saltpeter (potassium nitrate), charcoal, and sulfur. To say that these particular alchemists failed at their appointed task would be the understatement of the millennium. Not only did this “potion” completely fail to extend the life of anyone, this particularly potent mixture of chemicals became responsible for shortening the lives of perhaps more people than any other invention in the history of humanity.
This invention was, of course, gunpowder: the combustible substance responsible for every firearm that has ever existed in the real world and, by extension, every firearm in Fortnite.
Before we start looking at the science behind all the weird and wacky weapons in Fortnite, we need to explore a little bit about how gunpowder works. What is it, specifically, about this happenstance mixture of three common, everyday chemicals that led to the creation of everything from a pirate cannon to the SCAR assault rifle?
As mentioned above, basic gunpowder is a mixture of potassium nitrate, charcoal, and sulfur. Contrary to popular belief, gunpowder does not really explode, exactly (at least, not in the same way that something like TNT explodes). Rather, the combination of these three chemicals, once ignited, simply burns at an extremely high rate of speed. Under certain conditions, this fast-burning powder can seem to explode, but we’ll get to that shortly. First, we need to look at the three chemicals that make up gunpowder.
Let’s start with sulfur. Sulfur is the same chemical that you find on the tip of a common matchstick. If you’ve ever seen anybody light a match, you know that once it sparks just a little, the rest of the sulfur burns very quickly.
Charcoal is also something you have seen often, most likely in your backyard barbecue. Charcoal is a very dense carbon substance, but provides a lot of potential energy for a fire.
So, with sulfur and charcoal, you have two different flammable substances mixed together—one that burns very quickly, but doesn’t contain a great deal of energy, and one that burns more slowly, but does contain a whole lot of energy. What happens when you mix them together? Clearly, you will get a substance that burns quickly and has a lot of energy, right? Isn’t that basically what gunpowder is? And if so, what do you need with a third ingredient?
Sure, if you mix sulfur and charcoal together in a big pile and then toss a spark on top, you’re going to get a nice big fire. But you won’t get nearly as big a reaction as you will once you add potassium nitrate.
As we discussed in the chapter on jetpacks, any kind of fire needs both fuel and oxygen to burn. So if you were to mix sulfur and oxygen together and set them on fire, your little inferno would need to pull in oxygen from the environment surrounding it to achieve ignition. This will certainly work if all you want is a fire, but the process of the fire pulling in all that oxygen from the air is actually quite slow. That’s where the potassium nitrate comes in.
Potassium nitrate is an oxidizer, which essentially means that it acts as a source of oxygen for a chemical reaction. In the case of gunpowder, potassium nitrate is an especially effective oxidizer, because, as a crystalline powder, it provides the oxygen needed for combustion without the need to pull in oxygen from the atmosphere.
So, by mixing a substance with a lot of stored potential energy (charcoal) with a substance that burns very rapidly (sulphur) and a source of easily available oxygen (potassium nitrate, a.k.a. saltpeter), you wind up with a powder that burns faster than nearly anything else invented by man. If you were to put a pile of gunpowder on the ground and light it with a match (please do not do this), it would not, however, create an explosion. Why not?
Due to the rapidity with which it burns, gunpowder actually derives its power from the amount of gas and smoke it creates when it burns.
Just like anything else, when you burn gunpowder, you are transforming it from a solid into a gas, and like all gases, the gases from gunpowder take up much more space than gunpowder does in its solid form. In other words, igniting gunpowder makes its volume increase dramatically in a very short period of time.
Of course, burning anything makes its volume increase, as well. Let’s say you have an ordinary wooden log that is exactly one cubic foot in volume. When you put the log in your fireplace and set it on fire, that log is transformed primarily into heat and gases (smoke, carbon monoxide, etc.) with a small amount of solid left over (ash). Pretty much every substance in the universe can exist at any given time (based on number of physical conditions) in one of three states: solid, liquid, or gas (yes, there is also plasma, but that’s just going to confuse the issue right now, so let’s not worry about it in this chapter). Water, for example, can either be ice, liquid water, or steam, depending on its temperature. If you put a piece of ice in a pan and put the pan on the stove, your ice will first melt into a liquid, and eventually boil off in the form of steam. The important thing to understand here is that regardless of what the material is, transforming it from a solid into a gas makes it take up a lot more physical space. With substances like wood and water, this is a relatively slow process. With gunpowder, however, this process happens almost instantaneously.
That said, even with gunpowder, if this transformation from solid to gas happens in a pile on the floor in your kitchen, you’ll simply wind up with a large plume of smoke filling the room. But what happens if you contain the solid material in something solid, not flammable, and too small to contain all of the gases before you ignite it?
To answer that question, let me ask you another one. What happens when you shake up a can of soda? Well, when you do that, you are transforming some of the liquid carbon dioxide inside the beverage into gaseous carbon dioxide. And just like with anything else that you transform form a liquid or solid into a gas, you wind up making a smaller volume of liquid into a larger volume of gas. As you well know, this creates a great deal of pressure inside the can: sometimes so much that if you were to open the can under all this pressure, the contents inside would explode out forcefully into your face. Don’t believe me? Go ahead and try it; I’ll wait here.
Convinced? Good, because the same basic process that happens inside that soda can is what happens with gunpowder inside an enclosed container: the gas contents expand greatly as they transform into a gas, building up pressure inside the enclosed space until something allows that pressure to be released, often with a rather violent explosion of force.