Gunpowder or black powder, as it is also called, is a chemical mixture of sulphur, carbon (charcoal) and potassium nitrate (saltpetre). It burns very rapidly and produces large volumes of hot gases and solids, making it very suitable for use as an explosive, propellant and pyrotechnic agent in crackers and fireworks. Generically, the term “gunpowder” may be used be refer to any propellant that is used in guns and other weapons. The traditional gunpowder is no longer used in modern guns. Modern firearms use newer propellants such as smokeless powder.
In the classification of explosives, gunpowder is considered a low explosive. This is because of its slow decomposition rate which produces a subsonic deflagration instead of a supersonic detonation which is a characteristic feature of high explosives. The gases and solids produced by burning gunpowder are capable of only propelling the bullet and do not have higher explosive power. For this reason, other explosives such as TNT are commonly employed in applications such as rock shattering.
The word “black powder” came into common use the 19th century. Today, it is used to refer to traditional gunpowder and to distinguish it from modern smokeless propellants. Smokeless powders produce larger amounts of gases and lower amounts of solids upon combustion, resulting in lower amounts of smoke. Black powder, on the other hand, produces more amounts of solids which produces a thick characteristic smoke. Because of certain disadvantages, it is no longer widely employed in modern guns.
The history of gunpowder spans over many centuries. Gunpowder was invented in China around 1000 AD. It was most probably discovered by Taoist monks and alchemists as a result of their experiments in the search for the elixir of life. Traditional Chinese medicine often made use of saltpetre and sulphur in various combinations. This may be another source for the discovery of gunpowder. Whatever be its origins, after its initial discovery, it was used for warfare by the Chinese within a short period of time. A variety of weapons such as flamethrowers, bombs and rockets were used by the Chinese in their wars against their enemies. The precursors of modern firearms also have their roots in China.
From the Chinese, the knowledge of gunpowder spread to different parts of the world. By the 13th century, it reached Japan, India, the Islamic world and Europe through the silk route and due to the Mongol invasion. The earliest use of gunpowder in the West was recorded by Roger Bacon in the 13th century. Initially, the use of gunpowder in warfare was met with resistance from the traditional feudal knights and Christian authorities. However by the 14th century it became widespread and even the Pope’s army began to use firearms.
The 14th century saw the development of better gunpowder manufacturing techniques. Corning i.e. the process of adding liquids to the constituents and shaping the resulting paste of moistened powder into grains, was also developed the same century. The later centuries saw the rapid adoption of gunpowder across the countries of Europe. Technological progress in other fields such as metallurgy led to the creation of better and portable firearms and hand guns. Until the 17th and 18th centuries, black powder was popularly used in firearms.
Today, black powder is no longer widely used. Because of disadvantages, it has been replaced with smokeless powder in modern weapons. Smokeless powder, as the name suggests, doesn’t produce much smoke upon combustion. In addition, it also burns cleaner and doesn’t cause fouling. It is also much safer to produce when compared with traditional black powder.
Chemically, gunpowder consists of the following three chemicals:
Sulphur: [10%] Sulphur acts a fuel and also decreases the ignition temperature. Additionally, it also acts as a catalyst and enhances the rate of combustion.
Carbon (Charcoal): [15%] Charcoal provides carbon which acts as the main fuel in gunpowder. When carbon burns in the presence of oxygen, it produces carbon dioxide which acts as the expanding gas.
Potassium Nitrate: [75%] Potassium nitrate is an oxidizing agent which supplies the oxygen required for the combustion of sulphur and carbon. In some types of gunpowder, potassium nitrate may be substituted with other types of oxidizing agents.
The composition and manufacturing procedure of gunpowder was standardized in the year 1780. This standard stipulates 10% of sulphur, 15% of soft charcoal and 75% of potassium nitrate. However, the ratios can be changed depending on the purpose for which the resulting gunpowder may be used. In some types of gunpowder, different chemicals may also be used. For example, “blasting powder”, a special type of gunpowder that is employed to blast off rocks is made by substituting a portion of potassium nitrate with sodium nitrate.
Among all the three constituents, potassium nitrate plays the most important role because it supplies oxygen which initiates the rapid combustion of charcoal and sulphur, the main fuels in the mixture.
When gunpowder burns, the by-products cannot be determined with accuracy. The combustion process is also not a single step reaction. However, the end products can be determined and are found to consist of solids such as potassium carbonate, potassium, sulphide, potassium thiocyanate, etc. and gases such as carbon dioxide, carbon monoxide, hydrogen and water among others.
Though popularly used for many centuries prior to the invention of smokeless powder, gunpowder has certain disadvantages. When compared to modern smokeless powders, gunpowder has low energy density. In addition it also produces thick smoke which not only hinders aiming but also reveals the position of the shooter. Black powder also tends to produce a thick soot layer in the gun barrel. This soot is caustic in nature and can cause corrosion of the metal barrel. It can also cause the gun to get jammed. For this reason, guns using black powder have to be regularly cleaned. Poor maintenance of the gun can be lethal to the shooter.
To overcome the disadvantages of gunpowder, smokeless powders were developed. These are nitrocellulose based and were developed from another explosive called “gun cotton”. There are three types of smokeless powder, namely: Cordite, Ballistite and Poudre B. Additionally, modern smokeless powders are also classified into two categories: Single base and double base powders. Single base powders contain nitrocellulose alone. On the other hand double base powders contain nitro-glycerine in addition to nitrocellulose. Stabilizers such as diphenylamine are also added as minor ingredients to improve the stability of the powder.
Smokeless powders represent one of the major developments in firearms technology. They will continue to be used on a large scale for many years to come. However, newer technologies are being actively researched and in a few decades gunpowder based firearms may become completely obsolete to be replaced by better and far more accurate and lethal technology.