Smokeless Powders: Cordite

In our last post, we studied the invention of ballistite by Alfred Nobel in France. In today's post, we will study how Britain managed to obtain a similar smokeless powder: cordite.

As we saw previously, the French had managed to invent a smokeless powder for military use in 1884, which they called Poudre B and had developed a new rifle, the Lebel M1886 rifle in 1886, after which other governments became aware that the French had a new secret propellant that was superior to black powder. Shortly after this, Alfred Nobel invented ballistite in 1887 and tried to sell it to the French military. However, since they had already settled on using Poudre B and partly because of Poudre B's inventor, Paul Vieille, having connections with the French military, the French turned Alfred Nobel's offer down, even though ballistite was superior to Poudre B. Therefore, Nobel tried to sell his invention to other countries and managed to make a sale to the Italians. While the French weren't about to reveal the secrets of Poudre B to others, Nobel was selling ballistite to anyone who could pay him. In 1888, the British government formed a special commission to gather information about Vieille's and Nobel's discoveries. The British feared that if a smokeless powder was actually invented, they needed to get access to the technology as soon as possible, in order to remain a world power. The British commission's mandate was "to investigate new discoveries, especially such as affected the use of military explosives, and to submit to the War Office, proposals for the introduction of any technical improvements in the field."

One of the two scientists that the British put in the commission was Sir Frederick Abel, who we studied about in previous posts. Abel was instrumental in improving the Von Lenk process of manufacturing gun cotton and making it safer. The other scientist was Sir James Dewar, who was also a well known chemist and physicist of that era.

Sir Frederick Abel

Click on the image to enlarge. Public domain image.

Sir James Dewar

Click on the image to enlarge. Public domain image.

Nobel was pretty well acquainted with both men. Abel was actually a sort of rival to Alfred Nobel about 20 years previously, when Nobel had tried to set up a factory to manufacture dynamite in Britain and Abel had managed to convince British authorities that gun cotton produced by his process was safer to make and thereby prevented dynamite from being sold or manufactured in Britain for a long time. However, as time passed, the two rivals had become somewhat friendly to each other, even exchanging letters and occasionally meeting each other in Paris or London to discuss technical matters. James Dewar was a close friend of Abel and he too had corresponded with Nobel before on technical matters in chemistry.

As part of the commission's study, they requested some detailed information about production and samples of ballistite, which Nobel readily supplied to them. They also carefully studied Nobel's patent claim for ballistite in France. This is where Nobel's patent claim came back to haunt him. His patent for ballistite stated that "ballistite was a combination of equal parts of nitroglycerin and nitrocellulose "of the well known soluble kind", with about 10% camphor. " The wording here is very precise and your humble editor has taken the liberty of highlighting a few bits, because they are important to the next few paragraphs.

So in 1890, Nobel's Explosives Company in Scotland obtained a British patent for ballistite and tried to market it to the British War Office, only to be informed that they had already acquired a patent for a smokeless powder invented by Abel and Dewar, called "the committee's modification of ballistite", or cordite. While looking at Nobel's patent notes on ballistite, the two chemists noted that they could make a few small changes to the original formula and get similar results with the modified formula. Therefore, they quickly took out a patent in secret for their new substance and told the British military about it first, before informing Nobel about it.

Cordite had a few minor modifications to the original ballistite formula. It used vaseline instead of camphor, which was a better stabilizer anyway. Secondly, it used a larger proportion of nitroglycerin in its formula. Thirdly, the formula for ballistite had specified nitrocellulose "of the well known soluble kind" (i.e. a collodion paste that was soluble in water). The formula for cordite used the insoluble form of nitrocellulose (i.e.) gun cotton instead.

Of course Nobel was extremely angry about this and launched a patent infringement lawsuit immediately. The case dragged on to the Chancery Division Court in 1892, which ruled against him. Nobel appealed again and the case got pushed up into higher courts until it reached the House of Lords in 1895, which also ruled against Nobel, due to technicalities in his original patent application, and he was ordered to pay court costs. The problem was that his patent clearly specified that it used "the well known soluble kind of nitrocellulose", whereas cordite used the insoluble kind. The Lord Justice Kay was actually quite sympathetic to Nobel in his remarks: "It is quite obvious that a dwarf who has been allowed to climb up on the back of a giant can see farther than the giant himself ... In this case, I cannot but sympathize with the holder of the original patent. Mr. Nobel made a great invention, which in theory was something extraordinary, a really great innovation -- and then two clever chemists got hold of his specifications for the patent, read them carefully, and after that, with the aid of their own thorough knowledge of chemistry, discovered that they could use practically the same substances with a difference as to one of them, and produce the same results one by one". Therefore, what Abel and Dewar had done was probably morally wrong, they were technically and legally in the right, as cordite was sufficiently different from ballistite to have its own separate patent.

Nobel was naturally not very happy with the court decision, but he did manage to sell ballistite to quite a few other countries. After a few years, ballistite was being used by the militaries of Italy, Germany, Austria-Hungary empire, Sweden and Norway. Poudre B was being used by France, Russia and USA. Cordite became the predominant propellant used by the British empire, many countries in South America and Japan. Nobel's Explosive Company eventually manufactured both ballistite and cordite (even though his lawsuit caused the British government to not award any contracts to his company for over a decade afterwards). The company paid Nobel a half portion of the royalties from every batch of cordite produced, so he did make some money in the end.

In the next couple of posts, we will study the process of making cordite in some detail.

Smokeless Powders: Ballistite

In our last post, we talked about developments of smokeless powders in France, leading to the invention of Poudre B smokeless powder. In today's post, we will study about another smokeless powder that was developed in France as well, but it wasn't developed by a Frenchman. Instead, it was developed by an Swedish inventor who happened to be living in Paris at that time. We will study the invention of Ballistite.

Alfred Nobel. 

Click on the image to enlarge. Public domain image.

The Swedish inventor we are talking about is Alfred Nobel, who was a prolific inventor and was well known for inventing dynamite (and later, founding the Nobel prizes). Alfred Nobel's father, Immanuel Nobel, owned an armaments factory and Alfred and two of his brothers, Ludvig and Emil Nobel, were all interested in manufacturing better armaments and explosives. Alfred Nobel devoted a lot of his time to studying how to manufacture explosive substances safely and invented (among other things) a detonator, the blasting cap, dynamite, gelignite etc. These inventions (along with shares in the largest oil refinery in Russia, which was founded by his brothers, Ludvig and Robert) made him a very rich man and in 1873, he bought a large mansion on Avenue Malakoff in Paris and moved there. Despite his riches, he did not forget his interest in chemistry and still continued doing research in his laboratory.

It is not known exactly how he discovered how to make ballistite, but from his notes, it appears that he had been working on and off to make a smokeless powder since about 1879. He experimented over many months with various acids to make many explosive prototypes, which he tested at a blasting range outside Paris and then worked with assistants to perfect the manufacturing process. He didn't keep very many detailed notes mainly because of the need to protect trade secrets from competitors.

In 1887, a few months after Poudre B was accepted by the French government, Alfred Nobel submitted a patent application for his own smokeless powder, which he called "ballistite". According to his patent application, this was a combination of equal parts of nitroglycerin and nitrocellulose "of the well known soluble kind", with about 10% camphor. The exact wording on the patent application would come back to haunt him, as we will see in our next post. The purpose of the camphor was to react with any acidic products formed by the decomposition of the other two explosive substances. The camphor helped stabilize the other two substances from further decomposition and prevented explosions. In his 1887 patent application, Nobel wrote, "Celluloid, as a rule, contains nitrated cotton to approximately two-thirds of its weight, but owing to the camphor content and substance's compact consistency, celluloid's combustion, even if fine-grained, is far too slow to make it suitable as a propellant for projectiles. By substituting nitroglycerin, wholly or in part, for camphor, it is possible to produce a kind of celluloid with sufficient consistency to be formed into grains and which, on being loaded into firearms, burns with a subdued rate of combustion."

Like the Poudre B that we studied in the previous post, ballistite is also a substance that burns with much more force than black powder, but produces very little smoke and residue as well. Like Poudre B, it is also a plastic that can be shaped like dough and cut into precisely shaped and sized grains to fit the needs of everything from the smallest pistol to the biggest cannons.

So when Alfred Nobel triumphantly presented his latest invention to the French military in 1887, he was surprised to be rebuffed. It turns out that the French had just settled on using Poudre B a few months earlier in 1886 and Paul Vieille's political connections ensured that Poudre B would be used by the French military even though ballistite was a superior product. Nobel angrily wrote that "for all governments, a weak powder with strong influence is obviously better than a strong powder without this essential complement." Nevertheless, he went about marketing his invention to other countries and on August 1st, 1889, he obtained a contract from the Italian government and opened a new factory in Turin where he manufactured about 300 tons for the Italians. The next year, he licensed his patent to the Italian government for a large sum of money, so that they could manufacture it by themselves. The Italian army, in turn, replaced their old black powder rifles and adopted a new M1890 Vetterli rifle which used ballistite cartridges.

During that period of time, France and Italy were competing with each other, to become great powers in Europe. Naturally, the news that a person living in Paris and helping their enemy with manufacturing superior cartridges did not sit very well with the French public and military. The French newspapers launched a series of articles attacking Nobel's character, accusing him of treason (despite him offering ballistite to the French first and living in France for 17 years) and claiming that he had spied on Vieille and stolen his recipe for ballistite from the laboratories of the French Administration des Poudres et Salpetres. The police conducted a search on his laboratory and shut it down, his testing range permit was revoked and he was prohibited from manufacturing ballistite in France. Therefore, in 1891, Nobel packed up his possessions from his mansion in Paris, along with any laboratory equipment that hadn't been seized, and moved everything to San Remo in Italy, where he bought a large house that he named Villa Nobel. He also built a laboratory close to his new house and continued experimenting there for the rest of his life.

It must be noted that the production process of ballistite involved making flexible sheets, which were cut into flakes in cutting machines, or in pastry cutters, or squirted through gratings to form threads. It was a curious fact that many machines that were originally used in Italy to make bread, pastries, pasta, spaghetti and macaroni, were now employed in the manufacture of smokeless powders!

Italy wasn't the only country that Alfred Nobel was marketing his invention to. In the next post, we will study how he accidentally helped Britain to make their own smokeless powder.

Propellants: Smokeless Powders

In the last couple of posts, we studied the manufacturing techniques of black powder. In this post, we will study the next development of propellants, namely smokeless powders. First, let's get a couple of common misconceptions out of the way:

1. There is no single smokeless powder. Instead, the term applies to a number of different powders, all made of different ingredients.
2. Smokeless powders are not truly smokeless. It is true that during combustion, most smokeless powders burn up most of their mass into gaseous products, unlike black powder, which leaves behind 55% of its weight as solid residue. However, there is still some smoke produced.

Smokeless powders provide much more propellant force than the same amount of black powder, which made it possible for weapon ranges to increase. Since smokeless powders don't leave behind as much residue as black powder does, the weapons require less cleaning after use. The development of semi and full-auto weapons was also made possible because of the fact that there is very little residue and thus cannot easily jam the many moving parts of an automatic weapon.

While we noted in our post about propellant basics, that materials classified as "low explosives" are suited for propellants, smokeless powders generally contain a good percentage of high explosive materials such as nitroglycerine (go read the post on propellant basics to understand the difference between low explosives and high explosives and why low explosives are used with firearms). The way it works is that even though the propellant has a high explosive substance, a stabilizing chemical is also added to slow down the burn rate of the high-explosive so that it behaves more like a low-explosive.

The first smokeless powders were made in 1846, when both nitrocellulose (gun cotton) and nitroglycerine were first developed in Europe. The invention of gun cotton was actually the result of a happy accident. A Swiss scientist named Christian Schonbein was forbidden by his wife from conducting chemistry experiments at home, but he didn't always obey her. One day in 1845 when she was away, he accidentally spilled a mixture of strong nitric and sulfuric acids in the kitchen. He quickly wiped the mess up with his wife's cotton apron and then hung it over the stove to dry. To his surprise, the apron ignited and disappeared almost instantly, leaving behind almost no ashes. What Schonbein had done was accidentally manufacture nitrocellulose. Soon, with the help of another professor, he came up with the recipe of one part of fine cotton fibers, combined with fifteen parts of an equal blend of sulfuric and nitric acids. The cotton is dipped in the acid mixture for two minutes and then washed in cold water to remove any acids. Then the cotton is dried at moderate climate temperatures to form nitrocellulose. This material provides less heat and smoke and upto six times the explosive force of the same volume of black powder. However, guncotton was notoriously unstable and therefore, the British, French and Prussian governments stopped using it soon after. However, the French continued to perform experiments to improve its stability.

In 1884, a French chemist named Paul Viellie succeeded in improving guncotton's stability issues. He discovered that by treating guncotton with a mixture of alcohol and ether, it could be gelatinized. The material could then be rolled into sheets, cut into small squares or flakes and then stabilized with a 2% solution of diphenylamine. This formulation was codenamed Poudre B by the French government and it was a closely guarded secret. This formula produces a substance that is much more stable than guncotton and it will not detonate unless it is compressed. Unlike black powder, Poudre B also burns when wet and produces about three times the force for the same volume. This was the first "single-base" powder. The French developed the 8 mm. Lebel cartridge (the first smokeless military cartridge) and a new rifle, the Lebel Model 1886 to use this new technology.

In 1888, Alfred Nobel (the same person who started the Nobel prizes) discovered that he could gelatinize nitrocellulose by using nitroglycerine. The chemical formula was 45% nitroglycerine, 45% guncotton (nitrocellulose) and 10% camphor. He started to market his invention as "Ballistite" and it was the first "double-base" powder. The presence of nitroglycerine gave ballistite an even greater range than Poudre B. Nobel Industries set up a plant in Scotland to manufacture ballistite.

In the very next year, the British government appointed an "Explosives Committee" to monitor and study developments in other countries. They obtained samples of Poudre B and Ballistite, but decided that neither was suitable for adoption in UK. Two of the committee members, Frederick Abel and James Dewar, discovered that by combining 58% nitroglycerine, 37% guncotton (nitrocellulose) and 5% vaseline and dissolving the mixture in an acetone solvent, they could produce a paste which could be squeezed through a die to form a long thin string or cord of 1 to 5 mm. diameter depending on the application. From the cord, small pieces and shavings could be cut mechanically using a knife or a file, or it could be ground up using a device similar to a coffee grinder. In most cases, it was cut into small strings and packed into a cartridge case like spaghetti. This material was naturally given the name "cordite". It is also a double-based explosive like ballistite and later, a triple-base cordite was also invented. Abel and Dewar were the target of a lawsuit by Alfred Nobel, who felt that they had merely modified Ballistite slightly. The case took several years to be resolved and eventually reached the House of Lords, where the court ruled in favor of Abel and Dewar.

Disassembled cartridge. Note the light brown strings of cordite which were packed inside it.

An interesting feature of cordite (and some other smokeless powders as well) is that if the strings are burnt outside the cartridge, then they burn rather slowly with a yellow flame and no explosion. Cordite only explodes if it is lit in a confined space (such as a cartridge packed with cordite). It is also very resistant to shock. For example, it is possible to shoot cordite with a rifle bullet and still not explode it.

The first version of cordite was labelled Cordite Mk-1. The original version was the cause of early gun barrel erosion and so a new version was invented. This version had 65% guncotton, 30% nitroglycerine and 5% vaseline and was dissolved in acetone and was dubbed Cordite MD (MD for Modified). This version did not damage the barrels as much, but exploded with lesser force than Cordite Mk-1. Hence the cartridges were made to contain 15% more material to maintain the same force as Cordite Mk-1.

During WW-I, due to a shortage of acetone, Chaim Weizmann (later, the first president of Israel) invented another formula for use by the Royal Navy. This formula was called Cordite RDB (for Research Department Formula B). It was made by combining 52% guncotton, 42% nitroglycerine and 6% vaseline. Cordite SC (SC = Solventless Cordite) was invented before WW-II and used for larger guns (such as anti-aircraft). Another development in WW-II was Cordite N. This was made by combining cordite with nitroguanine, which is another explosive. Cordite N was the first triple-base explosive.

Despite all the improvements, cordite started to lose popularity around the middle of WW-II when newer propellants were invented. By the end of the 20th century, the last cordite manufacturing plant closed down.

One series of powders developed during WW-I to replace cordite was called IMR (Improved Military Rifle), which was developed by Dupont to replace the older MR (Military Rifle) series of powders. There were a number of IMR powders developed between the two World Wars. They are made of nitrocellulose, but contain dinitrotoluene (DNT) to slow down the burn rate of nitrocellulose to a low explosive. Graphite is also added to minimize static electricity and a small amount (0.6%) of diphenylamine is used as a stabilizer. A small amount (1%) of potassium sulfate is added to decrease the amount of muzzle flash. The powder is extruded out in the form of sticks. Different IMR powders were used to manufacture such famous cartridges as the .30-06 used by Enfield and the Mauser 7.92x57 mm. IMR powders are still used to this present day and are sometimes known as "stick powder" because the process of extrusion creates sticks of the propellant.

In 1933, another invention was the ball-powder propellant. This is made by dissolving guncotton in ethyl acetate and then forming the round grains under water. This process is similar to how round oil droplets are formed when mixing oil in water and shaking the contents of the bottle. Nitroglycerine is added to the grains to increase the explosive force and dinitrotoluene or a similar substance is added to slow down the burn rate. Like IMR powders, there are a number of ball powders as well using slightly different proportions and different substances to slow down the burn rate. Ball powders started to gain popularity in the 1950s. For instance, the ball powder WC 844 is currently used in the NATO 5.56x45 mm. cartridges.

The advantages of ball powder over other types of smokeless powder are many. For one, it takes a lot less time to manufacture than other types. Most other smokeless powders take a few months to manufacture. Dupont did manage to get one IMR powder type to be manufactured in 2 weeks. In contrast, one production lot of ball powder could be made in under two days. Ball powder can also be stored longer than other types. Excess acids during the manufacture of smokeless powder cause the powder to deteriorate more quickly. The ball powder manufacturing process is more efficient in eliminating most of the excess acid and it doesn't produce much acid as it ages either. The manufacturing process is also safer as it happens under water and also requires much less specialized equipment to set up a manufacturing line.