| Fourth of July celebrations are never complete | | | | wide and 5 meters long. The whole pile is covered |
| without fireworks. Since we were kids, we've | | | | from the rain and kept moist with urine. (Ok can it |
| enjoyed the wonder and magic of fireworks. We've | | | | get any gross?) It was often turned to accelerate |
| wondered where it all came from, how it all got | | | | decomposition and leached with water after a year. |
| started and what's in fireworks. | | | | After all that, the liquid that contained the various |
| There is an old fable about a Chinese cook who | | | | nitrates was converted with wood ashes to |
| accidentally mixed the three common kitchen | | | | potassium nitrates, crystallized and refined for use in |
| ingredients - saltpeter or potassium nitrate, sulfur and | | | | gunpowder. In England this privilege of making |
| charcoal and lighted it. It produced colorful flames as | | | | gunpowder and explosives was a monopoly of the |
| well as making a huge explosion when enclosed in a | | | | family of John Evelyn since before 1588! |
| bamboo shoot. This discovery led to the invention of | | | | Today the scene is different. Potassium nitrate |
| sparklers and firecrackers. There is evidence that the | | | | comes from deposits of sodium nitrate in the Chilean |
| Chinese used fireworks for entertainment as well as | | | | deserts. The sodium nitrate is purified and then |
| to cast away evil spirits since 206 BCE - AD 220. But | | | | reacted with potassium chloride where the |
| the Chinese discovery of fireworks is just one side | | | | less-soluble potassium nitrate is precipitated out. Now, |
| of fireworks story. | | | | that sounds much better doesn't it? |
| Fireworks were also thought to have originated in | | | | Sulfur is used in fireworks because of its flammable |
| India. There are references in ancient Hindu literature | | | | nature. There are two ways to get sulfur - the |
| to smoke balls suggesting the knowledge of | | | | Sicilian process, which was first used in Sicily and the |
| gunpowder. In the famous Ramayana myth | | | | Frasch process. In the Sicilian process, the sulfur from |
| Vishwamitra uses a weapon called the shikhara - | | | | rocks present in volcanic regions are extracted. First |
| which led historians to conclude that the ancient | | | | the sulfur deposits are piled and stacked in brick kilns |
| Hindus were acquainted with gunpowder. It would | | | | built on sloping hillsides with airspaces between them. |
| not be surprising as the ancients share the silk route | | | | The powdered sulfur is then put on top of the sulfur |
| for trading. The same trade route used by Marco | | | | deposit and lit on fire. It produces heat as the sulfur |
| Polo and the Arab traders which transported | | | | burns and melts the sulfur deposits, causing the |
| fireworks into the west. | | | | molten sulfur to flow down the sloping hillsides. The |
| Fireworks were used as fuel to power rockets that | | | | molten sulfur can be then collected in wooden |
| had arrows in them. In the 6th century the Chinese | | | | buckets. They then purify the sulfur through |
| would use these rocket arrows against the Mongol | | | | distillation. |
| invaders. The principle behind these rocket-arrows is | | | | Frashch process is a more scientific process where |
| still used today when we see the fireworks. | | | | three concentric pipes are used. Outermost pipe |
| Back in those days black powder wasn't easily | | | | contains superheated water which melts the sulfur |
| available so nitre-beds had to be prepared by mixing | | | | and the innermost pipe is filled with hot compressed |
| manure with either mortar or wood ashes. Common | | | | air which makes foam and pressure. The resulting |
| earth and organic materials like straw to allow air to | | | | sulfur foam comes out of the middle pipe. This |
| circulate inside. A typical pile is about 1.5 by 2 meters | | | | process produces sulfur with 99.5% content purity. |