FEATURE ARTICLE The Incredible Journey of Nitrates and Ammonia D.K. Srivastava & V.S. Ramamurthy The recent devastating explosion in Beirut was caused by 2750 tons of ammonium nitrate, a chemical compound commonly used as an agricultural fertiliser, but also known as the grandfather of explosives. T was on the evening of 4 August 2020, that Beirut, the capital city of Lebanon, Iwitnessed one of the largest industrial accidents amid the COVID-19 pandemic and an economic crisis. A powerful explosion sent a huge orange fireball into the sky, followed by a massive shock wave that overturned cars, damaged buildings, and shook the ground across the city killing at least 220 people, injuring more than 5000 and leaving an estimated 300,000 people homeless. The explosion was caused by 2750 tons of ammonium nitrate, a chemical compound commonly used as an agricultural fertiliser, which had been stored at the port warehouse for six years. Serious industrial disasters caused by ammonium nitrate were not Aftermath of the Beirut explosion (commons.wikimedia.org) uncommon in the past. Explosions due to Roger Pauly, writing in “Firearms: The Life History tons of ammonium nitrate on ships and in storage facilities of a Technology” suggests that, “While gunpowder was have caused hundreds of fatalities apart from damage to primarily a Chinese innovation, it may have received some structures, vehicles and even planes flying overhead. Indian inspiration. Just as China embraced Indian Buddhism, It is therefore not surprising that the news of about 740 the subcontinent’s fascination with fire may have crossed the tons of ammonium nitrate being stored in a container about Himalayas. In 664 AD an Indian visitor to China reportedly 20 kilometres away from the city of Chennai evoked such a demonstrated the peculiar flammability of saltpetre and panic amongst the public that the authorities had to complete provided instructions on how to locate it.” Arnold Pacey the process of disposal in a very short time and start moving (Technology in World Civilization: A Thousand-year History) the chemical away from there. adds, “Later Chinese studies of the chemistry of saltpetre Because of its easy availability, ammonium nitrate has show other evidence of Indian influence which seems to have also been used often by terrorists. been the starting point for the Chinese investigations which led to the first recipes for gunpowder.” Ammonium Nitrate – Grandfather of Explosives For centuries India was the biggest producer and exporter of potassium nitrate or saltpetre or “shora”. With charcoal and Sulphur, it produces an explosive mixture, which we now call gunpowder. Explosives were repeatedly mentioned by Kautilya in his Arthashastra, as “agniyogas” and “agnisamyogas” (https://csboa.com/eBooks/Arthashastra_ of_Chanakya_-_English.pdf). Some historians also suggest that Vaishampayan’s Nitiprakashika compiled in 800 BC and Shukraniti attributed to Shukracharya compiled perhaps earlier have mentions of explosives made using saltpetre, coal, and Sulphur. Saltpetre 36 | Science Reporter | November 2020 It is generally believed that the Chinese started using started using it for the subjugation of natives, extraction of gunpowder to make fireworks for display by 700 AD and gold, capture of territories and slaves, and piracy on the high the Mongols may have learned its use from them. The first seas; all of which led to their ascent. Saltpetre was one of the confirmed reference to what can be considered gunpowder most important chemicals exploited by the Europeans in their in China occurred in the 9th century AD, first in a formula initial trading days in India. contained in the “Taishang Shengzu Jindan Mijue” in 808, The Dutch East India Company is believed to have taken and then about 50 years later in a Taoist text known as between 3,000,000 to 3,500,000 Dutch lbs. per year for the “Zhenyuan miaodao yaolüe”. Holland alone, during the first two decades of the eighteenth Rana Hammirdeva of Ranthambore used gunpowder century (Susil Chaudhuri, Proceedings of the Indian History against the army of Alauddin Khiliji in early 1300 AD; there Congress, 1973, Vol. 34, 1973). In the year before the battle of are indications that some Mongol deserters from the latter’s Waterloo (1815) the East India Company exported 7300 tons army may have brought this technology with them. There of saltpetre to England (Robert Montgomery Martin, Statistics are reports of extensive fireworks in Vijayanagaram in 1443 of the Colonies of British Empire). The British victory at during the reign of Devaraya II during Mahanavami festival Waterloo was facilitated by the use of Indian saltpetre which in 1443, which may have used gunpowder. There is strong was far superior to the charcoal-like French product. During evidence to suggest that Chutia kings of Assam, used hand the American Civil War (1861-1865), Great Britain provided cannons (hiloi) as well as canons (bortop) against the invading saltpetre from India to the two warring factions. Ahoms in 1524 AD. Later, Ahoms used it against Turbak Around this time, Hyder Ali and his son Tipu Sultan Khan, the commander of Gaur in 1532 AD. started making very accurate and powerful rockets. Their main contribution was to fill the gunpowder in iron pipes and tie these pipes to long bamboo sticks, to guide them. During the Second Anglo-Mysore War (1861), Hyder Ali’s rockets had destroyed Colonel William Baillie’s ammunition stores, which contributed to a humiliating British defeat. Tipu Sultan greatly improved his rockets and deployed it extensively and very effectively. One of the guns which the Ahoms procured after defeating the Chutias in 1524 AD (Wikipedia) The First Battle of Panipat, on 21 April 1526, was fought between the invading forces of Babur and the Lodi dynasty. The battle is known for the use of gunpowder firearms and field artillery. It is generally believed that Babur got this knowledge from Turks, who may have learnt the use of gunpowder from Mongols, who in turn had learnt it from Chinese. It has been reported by Nathan (Baharistan-I- Ghaybi, M.I. Borah (tr.), Vol. I) that when Raja Pratapaditya of Jessore Painting of Mysore Rocket Man by Robert Home (Wikipedia) surrendered to Islam Khan in 1609, he agreed to provide 41 tons of gunpowder in addition to twenty thousand infantry and five hundred war-boats. About 50 years later, when Mir Jumla invaded Assam in 1662-1663 AD, he left with 675 big guns and 190 tons of gunpowder in boxes because they were of much better quality than what he was using. One of the reasons for the defeat of Nawab Sirajuddaula at Battle of Plassey in 1757 was that his gunpowder became wet due to heavy rain during the battle, while Robert Clive used tarpaulin to cover his gunpowder and “kept it dry”. This victory gave the English East India Company a monopoly over the vast sources of saltpetre in Bihar. It is truly said that “gunpowder and the cannon blew up the medieval world A painting by Charles H. Hubbell showing the Mysorean army economically and politically”. fighting the British forces with Mysorean rockets (Wikipedia, NASA) Saltpetre from India on the World Stage Why Bihar produced good quality saltpetre in such Earlier, European powers, which had made considerable vast quantities? Ashutosh K. Jha (Production of Saltpetre technological development in the use of gunpowder, had in Medieval India) writes that in this region, “… agriculture November 2020 | Science Reporter | 37 is the chief occupation and there is consequently a high The world produced more than 170 million tons of proportion of domestic animals. Thus, the soil around the ammonia in 2019. Ammonia is used for the production of villages has an abundant supply of organic nitrogen. The fertilizers like ammonium sulfate, ammonium phosphate, climatic conditions of temperature and humidity are also ammonium nitrate and urea. It is also used for the synthesis unusually favourable for the growth of so-called nitrifying of nitric acid, which in turn is used in making explosives such bacteria, which convert ammonia by successive stages into as TNT, nitroglycerine used as a vasodilator (a substance that nitrous and nitric acid. Wood and cow dung are largely used dilates blood vessels) and PETN (pentaerythritol nitrate), for fuel, and the immediate vicinity of each village thus forms sodium bicarbonate, sodium carbonate, hydrogen cyanide, a perfect laboratory for the formation of Potassium Nitrate. and hydrazine (used in rocket propulsion systems). In the long period of continuous surface desiccation which It is also used for making fibres like nylons and plastics, follows a small monsoon rainfall, the compound so formed used in large scale refrigeration plants and air-conditioning in the soil is brought to the surface by capillary action and units, and for making ice. Ammonia is an important input for appears as an efflorescence of salt which is collected and the pharmaceutical industry, pulp and paper industry, mining, purified.” and metallurgy, etc. Ammonium nitrate is also used as an By mid-nineteenth century nitrate from Atacama Desert oxidizer in rocket propellants and a nutrient for yeast and of Peru was available and India’s monopoly of saltpetre was antibiotics. challenged. The nitrates also used to be obtained from the walls of caves where the salts were brought to the surface Green Revolution and its Aftermath by moisture or from droppings of some seabirds or bats. Nitrogen has always been the most abundant gas in the The development of smokeless explosives like cordite and atmosphere since life was established on the planet Earth. later TNT reduced the use of saltpetre for making the black However, nitrogen atoms form a diatomic bond with each gunpowder. other, and the atoms cannot be taken up by organisms. The rate of conversion of atmospheric nitrogen to organic nitrogen Haber-Bosch Process is controlled by the enzyme nitrogenase.