(Confederate Adjutant General button)	The Civil War Relicman,  Harry Ridgeway
	Winchester, Virginia USA (changed hands 70 times in the Civil War!)
	I am a collector buying and selling authentic Civil War Relics
	This page updated   April 03, 2008

Historical Aspects and Black Powder Manufacturing

by Dr. Michael A Rosen

Black powder was the original gunpowder and practically the only known propellant and explosive until the middle of the 19th century. Although it can explode (only when tightly compressed), its principal use is as a propellant. Gunpowder was invented by Chinese chemists in the 9th century. Originally, it was made by mixing elemental sulfur (S), charcoal (C), and "saltpeter" properly named potassium nitrate (KNO₃). For the most powerful black powder "meal" a wood charcoal is used. The best wood for the purpose is pacific willow, however, grapevine, hazel, elder, laurel and even pine cones have been used. Charcoal is not the only carbon fuel that can be used. Sugar is used instead in many pyrotechnic applications.  The ingredients are mixed as thoroughly as possible. This is achieved using a ball mill with non-sparking grinding apparatus (using lead balls), or similar device. The ingredients are mixed as thoroughly as possible. 

When the ingredients were carefully ground together, the end result was a powder that was called 'serpentine.' The ingredients tended to require remixing prior to use, so making powder did involve a great degree of risk. Powder works realized that a good bit of the risk could be mitigated by making certain that the serpentine remained wet through out all but the last step of its manufacture. 

Black powder was also "corned" as a simple but effective means by which its burn rate could be adjusted. The initial step of the corning process was to compress the fine black powder "meal" into wet cakes or blocks of a "standardized" density (1.7 g/cm� or grams per cubic centimeter). The blocks, once allowed to dry would harden and become brittle, then broken up into granules. The granules would then be sorted by size to give the various "grain sizes" or grades of black powder. Standard grades of black powder run from the coarse and slower burning Fg grade used in large bore rifles and small cannon though FFg (medium and smallbore rifles), FFFg (pistols), and FFFFg the very fine and faster burning (small bore, short pistols and priming flintlocks). Very coarse black powder was used in mining before the development of nitroglycerine and dynamite.

Chemistry Composition and Combustion of Black Powder 

The optimum proportions for gunpowder are: 74.64% saltpeter, 13.51% charcoal, and 11.85% sulfur (by mass). The current standard for black powder manufactured by pyrotechnicians today is 75% potassium nitrate, 15% softwood charcoal and 10% sulfur. A simple, commonly cited, chemical equation for the combustion of black powder is: 

2 KNO₃ + S + 3C = K₂S + N₂ + 3CO₂

A more accurate, but still simplified[1], equation is: 

10 KNO₃ + 3S + 8C = 2K₂CO₃ + 3K₂SO₄ + 6 CO₂ + 5N2 

The products of burning do not follow any simple equation. One study's results showed it produced (in order of descending quantities): 55.91% solid products: Potassium carbonate, Potassium sulfate, Potassium sulfide, Sulfur, Potassium nitrate, Potassium thiocyanate, Carbon, Ammonium carbonate. 42.98% gaseous products: Carbon dioxide, Nitrogen, Carbon monoxide, Hydrogen sulfide, Hydrogen, Methane. 1.11% water 

Black powder is classified as a low explosive, that is, it deflagrates (burns) rapidly. High explosives detonate at a rate approximately 10 times faster than the burning of black powder. Although black powder is not a high explosive, the United States Department of Transportation classifies it as a "Class A High Explosive" for shipment because it is so easily ignited. Highly destructive explosions at fireworks manufacturing plants are rather common events, especially in Asia. Complete manufactured devices containing black powder are usually classified as "Class C Firework", "Class C Model Rocket Engine", etc. for shipment because they are harder to ignite than the loose powder. 

To summarize, black powder consists of a fuel (charcoal or sugar) and an oxidizer that supplies oxygen to the reaction during combustion (saltpeter or niter), and sulfur, a "matrix constituent" that allows a more stable, hotter, even burning combustion reaction. The carbon from the charcoal plus oxygen forms carbon dioxide and energy. The reaction would be slow, like a wood fire, except for the oxidizing agent. In order to burn efficiently carbon (charcoal) must be able draw oxygen rapidly from the air. The saltpeter (potassium nitrate) provides that extra oxygen. Potassium nitrate, sulfur, and carbon react together to form large volumes of nitrogen and carbon dioxide gases and potassium sulfide. The large volume of expanding gases, nitrogen and carbon dioxide, provide the propelling force imparted to projectiles by black powder combustion.

Additional questions and answers from Dr Rosen:

2. What is the detonating temperature of Civil War black powder?
IT DOESN'T EXPLODE ! Someone please clue-in the EOD on this point!!!!
First, black powder is not an explosive, it is a rapid burning propellant, and therefore it does not detonate. Potassium nitrate black powder can be ignited with a low temperature flame, but ignites more readily with a hotter flame closer to the decomposition temperature of potassium nitrate which is about 400�C. It is ignited in firearms using concussion and friction/spark. Merely heating it up won't ignite the propellant.

3. Is it highly sensitive to impact?
..........no way, friction can cause ignition however.........If the friction leads to sparking, static electricity (electrical sparking), or flame.............anyone or all of which serve as ignition sources to initiate the combustion (burning) of black powder. Static Electricity is a spark finer powder FFFG & FFFFG (the standard labelling for fineness "F" or in other words grain size "G". The greater the number of "F's" the smaller the size of the powder grains (fineness). Finer powder burns more quickly and, in turn, is therefore more susceptible to ignition by sparks. That same susceptibility to spark ignition is why FFFG and FFFFG (fine powder) is used to prime the flash pans of flintlocks. The cartridges would be loaded with a slightly coarser grade i.e. FFG or FFFG. Cannon would be loaded with FG i.e. large grained powder.

4. What is the mixture and percentages? 
See my Black Powder explanation.

5. If you drop a Civil War shell could it explode?
Only if it has a percussion i.e. fulmonate of mercury (mercury diisothiocyanate), detonator on its nose.

6. Does the powder get stronger with age?
NO

7. Does the powder turn to Nitro Glycerin?.
NO

8. What is the likely composition of "powder" after it has been flushed and what is happening when this residue is "cooked"?
I agree with the conclusions you have drawn re: the matrix, re: its composition after the KNO3 dissolved by water and washed away you likely have charcoal (carbon), elemental sulfur, and perhaps a bit of H2so4 sulfuric acid if it was sitting with water seeping in for decades. The technique that you employ to disarm explosive projectiles is both sensible and safe.  I can confirm that we are looking at a critical temperature which now you know to be approx. 400* F, so you want to warm not toast most certainly not bake these cute little iron (propellant filled) cupcakes.

One point re: terminology, black powder is not a compound, it is a mixture of 3 substances, the single compound KNO3, if pure, can readily solidify into a definite geometrical form, known as..............."crystalline". The black power "mixture" is just the opposite, it cannot form crystals and is referred to as "amorphous". The carbon can also crystallize, but it takes a great deal of heat, pressure and time.

9.  It has been claimed that a shell was detonated by cooking in Lee Sanzo's oven years ago.  At the time it was reported that Lee had a Schenkl shell in his oven "cooking", it detonated causing an interesting bulge in the oven, although none of the pieces left the confines of the oven and there were no injuries.  This accident was not investigated because there were no injuries and it happened years ago, so will be difficult to reconstruct the facts.  Could you comment on this?

"Potassium nitrate black powder can be ignited with a low temperature flame, but ignites more readily with a hotter flame closer to the decomposition temperature of potassium nitrate which is about 400�C. It is ignited in firearms using concussion and friction/spark. Merely heating it up won't ignite the propellant."

So gentlemen, Lee's "tale" was very entertaining, and was one of two that I read about this past weekend. But, as you know people's relatively poor understanding of black powder is mainly due to the fact that any knowledge that has been imparted to them is a "patchwork of fact and fable." Tales mixed in with some chemistry yielded a diversity of opinions expressed on that site that you showed me last night. In all due respect to Lee, and as a responsible scientist, you will have to show me an exploded stove, or at least some photographic evidence of same. Short of that, I can't explain a chain of events that I don't believe occurred. Unless something in that stove actually caught fire and then got to the powder in Lees shell, it didn't occur.

One argument against the "I cooked the shell in my stove to dry it and it blew up"................fable.
During a bombardment cannon would get red hot, the gunners needed thick leather thumbstalls in order to be able to thumb the vent to prevent air/oxygen from getting into gun allowing any embers or glowing material from flaming up and prematurely igniting charge being rammed. But they didn't bother to cool the guns down before loading, and I bet the bore temps. in a gun that has been fired continuously enough to empty a limber chest or two, would be well over 500 deg. F. Heat did not "cook off" black powder in those overheated guns, gunners simply needed to suppress flames by both:
1. swabbing out barrel with wet sponge, to extinguish any burning or glowing embers that could ignite the powder bag and its contents.
2. plugging the vent to keep oxygen out of the far end of the tube in order to suppress flames.

So, gentleman, in light of this very good example........................Lee's story could not have transpired......not as described, I believe that I could look him in the eye (I would hate to it) and tell him that I simply don't buy it, as gently and respectfully as I could possibly manage. I have chemistry and physics and the procedure of swabbing and loading a gun which are a clearly written part of the historical record, to make my case. What are Lee and the other guy with the same story (or Lee's story told by someone else) going to bring to the table to make their case??!! Show me that oven with the charred ruptured sheet metal with charred metal of the torn edges & small pieces of shrapnel embedded in its walls, then I will listen......................but will still look for how a flame got to that shell.

Editor note:  It is entirely possible that the melted mixture of sulfur, carbon, matrix from the canisters, or whatever it was, dripped out of the shell directly onto the heating coil in the oven.  This could well have caused the flame or spark needed to cause a detonation, if that flame traveled into the flammable mixture of the shell, that could cause a somewhat violent oxidation.  It should be noted that the "explosion" was not powerful enough to degrade the oven, a simple kitchen oven.  Consistent with the idea this is a propellant and not an explosive, this would seem to corroborate that conclusion.  A way to avoid re-occurrence of that accident is to simply set a drip pan below the shell so that none of the contents can get to the coil.

More questions for Dr. Rosen?  Submit questions, as I get more information or answers I will post it.

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