Black Powder XXI - Damaged Powder

In our last post, we saw how black powder that had absorbed some moisture in the field, could be reworked to become useful again. However, this reworking process only worked if the black powder had absorbed a smaller amount of moisture from the air (< 7% by weight). Unfortunately there were situations where the powder could absorb a lot more than this. In today's post, we will discuss what they did with the powder in the 19th century when this happened.

Remember that black powder was not always stored indoors in a warehouse under dry conditions. It may have been transported in the cargo compartment of a ship, or perhaps it was shipped by cart to some distant battlefield. There were plenty of situations where the barrels could have been exposed to a lot of water (e.g.) water frequently seeped into cargo compartments inside the ships and had to be periodically pumped out, carts could be driven through thunderstorms, the barrels could have been frequently opened and closed in wet conditions in the field etc. In such situations, the barrels could absorb a lot more moisture than 7% by weight and the powder was considered damaged. Armies and Navies would typically send this damaged powder back to the factory, where they would deal with it.

At the factory, they would first figure out how much moisture the powder contained, using the method we studied in our previous post. If it was well below 7% by weight, it could be dried and recovered, as we pointed out in our previous post. Another technique was to take a small amount of the damaged powder and mix it with a barrel of newly manufactured powder, so that the overall moisture content of this mixed powder was within tolerable limits. For instance, the mix could consist of about 10% damaged powder and 90% new powder and would have pretty much the same propulsive force.

However if the powder was too badly damaged by moisture, then they would usually try to recover the potassium nitrate from the mixture, as it was the most valuable ingredient. Remember that saltpeter (the source of nitrates) was a hard-to-obtain substance for many centuries and England controlled the source of most of the world's supply for decades. Therefore, many countries found it worthwhile to try and extract as much nitrate as possible from the damaged powder. For instance, in the Confederate States, they had a Damaged Powder Works in Augusta, Georgia, to which all damaged powder from the field was sent to.

At the Damaged Powder Works, they would empty 8 barrels (800 lbs.) of powder into a large copper vessel and then add about 200-240 gallons of water. The vessel was then heated until its contents began to boil. The boiling water would dissolve the potassium nitrates in the powder, while the sulfur and charcoal remained undissolved. After this, the hot water was pumped out of the vessel through a double filter arrangement and poured into shallow crystallizing pans, where the liquid would cool and form nitrate crystals. The crystallizing pans would be shaken while the liquid was cooling, so that the nitrate crystals formed would be of small size. Since charcoal and sulfur don't dissolve in water, they remain behind in the vessel and filters. This method could recover over 95% of the nitrate content in the damaged powder. The recovered nitrate crystals were then sent back to the gunpowder factory to be used to make black powder again.

In the case of lightly damaged powders, the Damaged Powder Works often reworked it to make blasting powder, which is a low-grade black powder with a lower percentage of niter and more dust. To do this, they would take the damaged powder and add more sulfur and charcoal, so that the percentage of niter was reduced. The mixture would then be incorporated for a short time and then granulated to form blasting powder.

The Damaged Powder Works not only recovered nitrates from damaged powder, they also tried to recover it from byproducts of the manufacturing process as well, since niter was such a precious substance. They would try to recover saltpeter from the sacks that it was shipped in, from sweepings from the factory floor of the powder mill and even from washing the workers' clothes. The remnants of the mother liquor from the niter refineries were also sent over, so that they could extract the last possible bit of nitrates from there.

Black Powder XX - Reworking and Re-Shaking

In our last post, we looked at different types of containers that black powder was shipped in, in the 19th century.

A stack of powder barrels. Click on the image to enlarge.

Now, it must be remembered that black powder is hygroscopic in nature, which means it tends to absorb water from the air. Despite the best efforts to provide a tight seal to the barrels, there is a chance that the powder inside may still absorb some moisture over a period of time, especially if there is a lot of relative humidity in the air. If the black powder absorbs sufficient moisture, then this reduces the burning rate and strength of the black powder. Moisture can also cause caking in the powder. Water also causes the potassium nitrate to separate out of the black powder and can cause corrosion of metal gun parts. Therefore, it was not a good idea to leave barrels stored in the warehouse untouched for many years. We will study some methods that were in use in the 19th century to handle the problem of the black powder absorbing water in today's post.

To handle the caking issue, barrels were generally filled to 90% of their capacity. For instance, in the above image, we see that the barrel holds 100 lb. of powder. The barrel is actually capable of holding about 110 lbs. of powder or so, but it is only filled with 100 lb. of powder, which leaves a little room available for the powder to move around. Therefore, the contents of the barrel are free to move during transport of the powder and this helps break up any large lumps. In England, they would roll the barrels every year over a copper plate on the floor of the magazine, with the idea that this redistributes the contents inside and prevent caking.

In many countries, it was standard procedure to examine the barrels after a certain amount of time had elapsed (which is why the date/year of manufacture was stamped on every barrel). For instance, in France, they examined the barrels once a year for moisture damage. First, they would put each barrel on its side and roll it on a floor covered with hair rugs. If the sound coming out of the barrel was uniform, that meant the powder was good. Any uneven sounds meant that there was likely some moisture absorbed and caked powder inside. In this case, they would open the barrel and determine the moisture content of the powder before deciding how to proceed.

To determine the moisture content in the powder, they would take three samples of powder, one from the top, one from the bottom and one from the middle of the barrel. The samples would be carefully mixed and then 5 grams of powder would be carefully extracted from this sample. This powder would then be subject to a drying process, like the ones we studied previously. After this, it would be weighed again and the difference in weight indicates the percentage of moisture content in the sample.

If the moisture content of the sample was found to be below 7%, then all the powder was simply taken out of the barrel and dried, either by using the sun, or by using an artificial drying process like the ones we studied a few posts before. The barrel was also dried separately. Then the powder was subjected to a dusting process and then re-packed into the barrel. If the powder inside the barrel was found to have clumps in it, then these were broken by hand and was put back into a dry barrel and re-shaken to break up any smaller lumps. 

If the moisture content of the sample was found to be greater than 7%, or if the saltpeter had begun to migrate out of the powder, then the powder was subjected to a chemical analysis to check if the proportions of the three ingredients were still within acceptable limits and if so, the powder was sent back to the mill to repeat the stamping process that we studied about a month ago.

Any barrel found to contain moisture was not put back to its original place in the warehouse after the reworking process. Instead, its position was swapped with another barrel from the stack of barrels, so that those that were in the bottom of the pile would now be on top and vice-versa. 

In Germany, they would expose the powder to sunlight at regular periods, whether the powder contained moisture or not. The Prussian procedure was to do this every two years, which later changed to every 8-10 years, if the barrels were located inside a dry powder magazine.

In our next post, we will study what was done if the powder was found to be in a damaged state. 

Black Powder XIX - More on Packing

In our last post, we talked about the packing process of black powder in the 19th century. However, that post went a little easy on details about the containers used, so we will discuss those in today's post.

Black powder was generally shipped in boxes (cases) or cylindrical containers. Barrels were used because they were designed to hold goods without risk of leakage and were used for centuries for this purpose. On the other hand, boxes are easier to stack on top of each other than barrels and waste less room.

The boxes were usually made of copper and had powder loaded in a linen bag, or they were made of wood (which was cheaper) and had a slightly smaller box inside, into which the powder was loaded. Boxes varied in size, depending on the country, the type of powder etc. For instance, in England, some cases were about 2 feet long, 2 feet wide and 6 inches high. In the Confederate States, their boxes were about one foot long, one foot wide and 2.5 feet long. In Austria, their boxes were big enough to contain about 64 lbs. of powder. For sea duty, the boxes were generally made of copper. While boxes cannot be rolled around easily like barrels, they can be packed together more tightly than barrels can, which is why some factories started to switch from barrels to boxes towards the end of the nineteenth century.

Containers generally came in multiple sizes: Barrels, Kegs and Canisters.

Barrels are generally the largest of these containers. Typical barrels of the nineteenth century were about 2 feet high and about 1 to 1.5 feet in diameter. Capacity of the barrels varied by country, but most could usually hold about 110-120 lbs. of powder. However, these barrels were usually only filled to about 90% of the capacity (e.g. they would only fill about 100 lbs. of powder to a barrel capable of holding 110 lbs.). This was done so that the powder would have room to move inside the barrel during transport and wouldn't get caked.

A stack of powder barrels made in England. Click on the image to enlarge.

Another stack of powder barrels. Click on the image to enlarge.

Most barrels would have a hole of about 1.5 to 2 inches diameter drilled to the top of the barrel, which would then be plugged with a wooden screw. This way, if someone wanted to access the powder inside the barrel, they only needed to remove the screw instead of the entire top of the barrel. A leather washer soaked in wax and turpentine would be placed under the screw head, which served to keep moisture out. The image below shows an example of this:

Notice the screw at the top of the barrel. Click on the image to enlarge.

Kegs were generally built on the same principle as barrels, but were much smaller in size, typically holding about 25 lbs. of powder. Also, instead of having an opening on top, most kegs had an opening in the middle to access the powder.

An example of a powder keg

Kegs are much easier to transport than barrels on account of their lesser weight and were favored in places where there wasn't much room to move around in (e.g. on board ships).

A couple of Civil War era powder kegs. Click on the image to enlarge.

Finally, we have canisters. Unlike barrels and kegs, these were generally made of metal and had the least capacity of the three container types.

A black powder canister. Click on the image to enlarge.

Powder canisters typically held about 0.5 to 1 lb. of powder. The above example is a canister made by the Eureka Powder Works of New Durham, New Hampshire. It is made of steel, is about 4.75 x 4 x 1.75 inches in size and has a paper covering on the outside with hunting scenes printed on it. Due to their small size and capacity, these are much lighter than the other containers we have studied above and are easy to transport. Unlike barrels and kegs, these were intended to be sold to private individuals rather than military units.

Parts of the Firearm: The Barrel

In our previous post, we studied the bolt carrier group. In this post, we will study about the barrel of a firearm. We've actually talked a lot about barrels in a number of posts in the past, but never really discussed the parts of a barrel in detail. We will do that in this post.

A barrel is simply a tube through which a bullet comes out of. Most firearms these days have a single barrel, though shotguns do come in double barrel versions. This is in contrast to previous centuries when multi-barrel firearms did exist. In most cases, the barrels are cylindrical tubes, but there are also polygonal barrels and oval barrels which have been used in history. With that said, let us discuss the various terms that describe barrels.

Bore: This is a word that describes the inside of the barrel tube. The inside surface may be rifled (more modern) or smooth (i.e. smoothbore, which is what the first firearms were like).

Breech: This is the rear part of the barrel (i.e.) the end that is closest to the firing mechanism. Most modern firearms are loaded via the breech end of the barrel.

Chamber: The chamber is at the breech end of the barrel. This is the area where the cartridge is placed into, prior to firing it. The most pressure exerted on the firearm upon firing occurs in the chamber area, hence the walls must be thick enough to withstand this pressure. The manufacturing of the chamber has a lot to do with the precision and reliability of the firearm. If the chamber fits the cartridge very tightly and precisely, then accuracy of the firearm is improved, but the reliability of feeding a new cartridge into the chamber is reduced. Conversely, if the cartridge fits the chamber loosely, then the feeding of a new cartridge into the chamber is much easier, but when the cartridge is fired, it will move around in the chamber and affect the accuracy of the bullet. Therefore, a good chamber design tries to strike a balance between these two factors.

An exception to this are revolvers, which have multiple chambers in a separate cylinder. In this case, the chambers are not part of the barrel.

Freebore: In the case of rifled barrels, this is the area just forward of the chamber, but before the area where the rifling starts. It is a smooth area that guides the bullet forward where it engages the rifling.

Muzzle: This is the part of the barrel which the bullet comes out from. For early firearms, they were usually loaded via the muzzle end of the barrel. The pressure generated by the burning gases decreases as it approaches the muzzle. Hence, some manufacturers make the walls of the muzzle end of the barrel thinner than the breech end, since it doesn't have to withstand as much pressure and they can reduce the overall weight of the firearm this way.

Devices such as flash suppressors or compensators may be screwed on to the muzzle end of the barrel.

The length of a barrel depends on the type of firearm. Rifles and shotguns have barrels starting from around 17-18 inches in length and go all the way to 60 inches or longer. Revolvers and pistols tend to have barrels in the 3-5 inch range, though there are exceptions to this rule of course.

When a cartridge is fired, the expanding gases act on accelerating the bullet as long as it is still within the barrel. Once the bullet leaves the barrel, the expanding gases no longer act on it and the bullet is no longer accelerated. Hence, if the barrel is longer, then the expanding gases act on the bullet for a longer time and allow it to come out with greater velocity than if the barrel is shorter. On the other hand, longer barrels are harder to aim with. Hence, the design of a firearm must strike a compromise between these factors.

Cross-sections of three barrel types. Public domain image

In the above image, we see the cross-sections of three different barrel types. The left one is a smooth bore barrel, the middle one is a rifled barrel and the right one is a polygonal barrel.