A Brief History of Gunpowder

From its origins in Chinese potions for immortality to the agent of death on the battlefield, the history of gunpowder is one of chemistry, ingenuity, and violence. Armorer Ron Potts fascinates with the tale.


Harmony Hunter: Hi, welcome to the podcast. I’m Harmony Hunter. Well today we’re talking about gunpowder; the history of gunpowder, the technology of gunpowder, the availability of gunpowder in England and the colonies. Our guest today is Ron Potts. He’s assistant armorer here at Colonial Williamsburg and he’s joined us to talk about his area of expertise or one of his areas of expertise and that’s gunpowder. Ron, thank you for being here today.

Ron Potts: Nice to be here. Thank you.

Harmony: Well where do we start with gunpowder? When does this enter into use?

Ron: Well, let’s start at the very beginning. I think that’s the best place. Where gunpowder originated is still open for debate among historians. Some believe it actually developed in Europe. I don’t believe that’s true. Could be the Arabic world, could be India, but I think the best evidence points to China.

The oldest story that I can find on gunpowder, and this is sort of an interesting one, it comes out of 850 A.D. At that time a Chinese alchemist wrote a book about different positions being used in China to allow the Emperor to live forever. One Emperor in China who was Emperor from about 804 to 820, a man by the name of Lin Chin, wanted to live forever so badly that he took 35 different potions.

Unknown to him, unknown to the alchemist that made these potions for him, some of them contained poisons. So what he actually did was shorten his life because he ended up dying from being poisoned. The book written in 850 basically talked about the 35 potions that he took. One of them he tells us was a mixture of saltpeter, which is one of the ingredients of gunpowder, sulphur, which is a second ingredient of gunpowder and instead of charcoal, which is the third ingredient of gunpowder the mixture contained dry honey. But the interesting thing about dried honey, it’s a carbon source.

He tells us when they were mixing these three ingredients together they exploded, burning the men who were working on it and burning down the house that they were in. So to me this is the earliest example of gunpowder; at least the road to gunpowder. And what makes the story interesting, of course, is the fact that its initial intention was to allow for humans to have eternal life and gunpowder, of course, has not done that.

Harmony: So when does it start being used to propel objects?

Ron: The Chinese start that too. Initially it’s just used to make loud noises, but they do begin using it in tubes. What they do is they put the gunpowder in the tubes and then ignite it so that the gunpowder comes out the muzzle end of the tube and it would be a weapon that would be used at close distance from the enemy because you’re not firing a projectile, you’re just firing gunpowder. So the intent is to burn the enemy in front of you, but you have to be within the range of the gunpowder itself so that’s not very far; 10-20 feet.

What slowly happened is, they began to put or they began to find little pieces of stuff: gravel, solid objects, and they began to realize it will also propel those objects and it will propel those objects further distances. So they started putting more and more pieces of lead, pieces of glass, whatever they had in the tubes and eventually within a 100 years or so they end up putting a large object, a bullet or a ball, and instead of trying to worry about burning somebody with the gunpowder they realize, you know, let’s hit them with a bullet, a ball, because that will go a much greater distance.

Harmony: You’ve mentioned the three ingredients in gunpowder. Let’s go back and talk about those. You mentioned sulphur, saltpeter and what was the third?

Ron: Charcoal.

Harmony: Charcoal. Where are those sourced? How do those come together?

Ron: OK. The interesting think about gunpowder for one thing it does not detonate. Gunpowder doesn’t actually explode. What it does is deflagrate. Deflagrate means it burns very fast. Now what burns in gunpowder is the charcoal and sulphur. Charcoal we know is a fuel. We all use it. We have used it for centuries. Sulphur is also, it’s one of the few elements found in nature that burns. It used to be called brimstone. Saltpeter is the key though, because saltpeter is actually the oxidizer.

Now specifically saltpeter should be potassium nitrate although especially in Europe they use calcium nitrate and sodium nitrate and magnesium nitrate. What you really want for gunpowder though, the best of all those, is the potassium nitrate. At the heart of a potassium nitrate molecule is a nitrogen atom that has three oxygen atoms connected to it. Now when you think about putting gunpowder in a gun, in a tube, that’s all it is is a tube closed at one end, let’s say we put charcoal in that too, just charcoal and we try to light it. It would probably light but it would burn out instantly because there’s no oxygen in that tube. We would burn out the oxygen. So we need to get oxygen in that tube and that’s what the saltpeter’s going to do for us. It’s the main ingredient in gunpowder and small arms like muskets, 75% at least of the ingredient is saltpeter.

Harmony: What exactly is saltpeter?

Ron: Saltpeter is actually a byproduct of two strains of bacteria that feed on human or animal waste. I’m putting that as politely as I can. The bacteria though also needs something to drink and it doesn’t like water so if you mix water with the waste you won’t get saltpeter. What you need to mix with the waste is urine. Once again, human or animal, bacteria’s not fussy. Although, and they knew this fairly on in Europe too by the way, if you can get urine from a human that drinks a lot of alcohol it’s actually better. Science has found out for us that the reason that is is because people that drink a lot tend to have more ammonia in their urine and that’s what the bacteria feeds on so what happens? You have a pile of waste and urine mixed with it, and this takes about a year for this to happen by the way, the ammonia will break down the nitrogen waste.

Along comes the first strain of bacteria. It’s called nitrosominas. Nitrosominas will come along and feed on that. Its waste is going to produce a nitrite. A nitrite is a nitrogen atom with two oxygen atoms connected to it. What comes along and feeds on its waste now is nitrobacter, the second strain of bacteria. It feeds on that, gets what it needs and then its waste is a nitrogen atom connected to three oxygen atoms which is our nitrite and that whole process takes about one year if you’re doing it yourself and instructions were also printed for the colonists to produce saltpeter. In other words, you build a pit, fill it with waste, organic matter, a little lime is good to maintain the ph balance and then periodically about once every two weeks wet it with urine, cover it so it doesn’t get rained on, crawl in the pit every once in a while and mix it up and within about a year you’ll start to see saltpeter crystals forming on your walls.

Once last thing; Americans did try this. We weren’t that successful at it I think for obvious reasons. It’s not the most pleasant thing to try to produce, but one person who actually made an attempt, John Adams, at the beginning of the war was a strong opponent for America producing saltpeter and gunpowder. His wife, Abigail, actually tried to produce saltpeter. She and a couple of her neighbors made a pit and tried to do it. They weren’t successful, but they give it the old college try, as one would say.

So what happens now, let me do this kind of in an order, if you could slow down the events that happen when you ignite gunpowder the first thing you would see happening is the sulphur would ignite because it ignites at a lower temperature; about 504 degrees. The sulphur then would help ignite the charcoal, which ignites around 750-840 degrees depending on the charcoal because you can use different woods.

In order for the nitrogen to break down in the saltpeter and release the oxygen you need to heat it to 635 degrees. That’s the charcoal’s job because it heats to 800 degrees. It’s going to break that nitrogen down and then release the oxygen which allows the rest of the sulphur and gunpowder in that tube to burn. Now the amazing part of all this; remember I said we want to slow it down. In a musket, a small arm tube, that whole process from start to finish, ignition to combustion, complete combustion, is about 7 milliseconds.

Harmony: It’s amazing to think about all the chemistry happening in that. I never stopped to think about it before.

Ron: Yea, and the interesting thing is, you know, during most of the history of gunpowder none of that was known. They don’t really understand or learn the chemistry and exactly what’s going on until the late 1800s, and by then gunpowder is kind of going on its way out because they have new explosives like TNT and dynamite and guncotton, which are explosives. They detonate and they explode much quicker than gunpowder.

Harmony: Let’s talk about the gunpowder that fueled the American Revolution –it was actually not a native product of the American colonies.

Ron: No. We made very little gunpowder here in America. The first gunpowder mill that I have ever come across was opened in Milton, Massachusetts in 1676 so we were making some gunpowder. The Milton Massachusetts Mill actually produced gunpowder up until about 1750 when it went out of business. I think the family just sold it off or it died out. My understanding is that they made some pretty good gunpowder but that was the only one that I know of. Now during the French and Indian War there were a few small mills and there’s always been individuals, especially in the frontier, that make it for their own use or for their neighbors. But by the time the American Revolution breaks out in 1775, there’s only one gunpowder mill operating in America and that’s the Frankfort Mill up just north of Philadelphia and its owned by a man named Oswald Lee and they’re not producing gunpowder there all the time. He only produces gunpowder when he has saltpeter so it’s a very sporadic production of gunpowder.

So when the war breaks out, it’s estimated that the Americans control about 80,000 pounds of gunpowder for our defense. Now I kind of want to make this clear: there’s a lot of privately owned gunpowder. Every militiaman is required to own at least a pound, sometimes more depending on the militia laws, and many of the stores in Williamsburg and throughout the colonies selling different items and guns would also be selling gunpowder. What I’m talking about is gunpowder for the defense of the colonies.

Now to put that in some sort of perspective, 80,000 pounds, well that sounds like a fair amount, in the first two and a half years of the war we do start making gunpowder. Obviously all of the colonies put out requests to their citizens, “If you can make gunpowder, please do it,” and if you say, “Well I don’t know how,” they actually print instructions for you to tell you how to do it and people respond. Americans will produce roughly 115,000 pounds of gunpowder for our defense.

But during that same period of time we receive from France, and I want to make clear I said receive, not buy, we are paying for some of it but not all of it. France is loaning us a lot of money. We receive from France about 1.7 million pounds of gunpowder. So you can see what we’re producing is next to nothing. In fact, by war’s end, some 90% of the gunpowder we will use in our fight against England will have come from France.

Harmony: This must have been a tremendous problem throughout the Revolution coming by gunpowder. You can’t have a war without gunpowder.

Ron: Absolutely. Yea, and to compound the problem, gunpowder doesn’t store forever because the potassium nitrate is a salt, it will absorb moisture and once that happens your gunpowder is ruined. So generally potassium nitrate gunpowder will store in wooden barrels which is generally how we do it, it will store somewhere between maybe three and five years. Beyond that it starts becoming useless. It won’t work at all actually. If it’s calcium nitrate, which they used in Europe for quite a while, you can only expect about three months out of that because calcium nitrate absorbs moisture easily.

Harmony: Do we see Washington or any other leaders writing about the problem of the shortage of gunpowder?

Ron: Yes, yes we do. In fact when Washington takes command the Army around Boston in ’75, in the summer of ’75, which was the New England Army basically holding the British in Boston, he writes Congress two facts that I found interesting.

One is that of the many they had there, 15% of them didn’t have a weapon. Which to me is a good indication that not everyone in the colonies owned a weapon. The assumption is because militia laws say, “Every free male, free able bodied male, needs to be in the militia if he’s 16 years old or up to 60,” leads us to believe then that every male has a gun; that’s the law. But the reality of it was, no, not everybody owned a gun. I don’t think it was a lot that didn’t own a gun, but 15 or 20% I think would be a fairly good guess as to how many men did not have guns and his letter is a good indication of that.

But the other thing that he wrote which I find incredibly fascinating is that he had available for that entire Army: 34 barrels of gunpowder. Now a barrel of gunpowder is 100 pounds so he had literally 3,400 pounds of gunpowder. That was enough gunpowder to allow every man in his Army seven rounds and that meant no gunpowder for any cannons whatsoever. Had the British known that, had General Howell known that in Boston that Washington had no gunpowder, he could have attacked and the war could have ended right there because we had no gunpowder to fight with. Fortunately the British didn’t know that and we do start getting gunpowder very quickly. We send our privateers down to the West Indies to purchase. There’s a desperate need to gunpowder.

Harmony: Such an interesting idea to think about when you think about the revolution, there’s so many components to it that are economical and functional and practical. You’ve given us such an interesting window into the operation of war.

Thank you so much for coming by today.

Ron: Thank you. Thank you. Appreciate it.


  1. As always a great piece of historical information. CWF informs, enlightens and educates at a level no other historical organization does.

  2. […] out of barrels (actually, as Ron Potts, assistant armorer at the Magazine, points out in this Past & Present podcast, gunpowder doesn’t explode, it deflagrates). Naturally, 18th century military stores usually […]

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