Nitroglycerine, or more specifically trinitroglycerine, is both highly explosive and highly unstable. Because it could not be handled safely, it had no practical application until Alfred Nobel invented dynamite in 1866.
Dynamite comprises sticks of porous clay (kieselguhr) that have absorbed nitroglycerine. Relative to raw nitroglycerine, dynamite is safe to transport and store. If stored for too long at too high a temperature, dynamite begins to “sweat”. The nitroglycerine begins to seep out of the clay, and returns to its highly unstable state.
Nitroglycerine is used in modern explosives and propellants.
Explosives decompose in a violent reaction that produces gas, heat, and a shockwave. The reaction is called a detonation, and passes through the explosive at the speed of sound. In modern explosives, nitroglycerine may be mixed with other explosive compounds. Nitroglycerine based explosives are often stabilised with wood fibres.
Propellants are used in firearms. They are a category of explosive designed to burn rapidly, producing gas to propel a bullet or larger projectile, but without detonating. If they were to detonate they would likely destroy the gun and injure those operating it. Propellants can be developed with different characteristics, but many are based on a combination of nitrocellulose (guncotton) and nitroglycerine.
Whether manufacturing nitroglycerine based explosives or propellants, at some point raw nitroglycerine has to be produced and transported to the part of the process where it is stabilised. Putting it in a closed container for transport would produce a bomb, exacerbating the effects if the nitroglycerine should detonate. Passing it through pipes would produce long and thin bombs, with similar consequences.
In the 1980s I visited a site that manufactured nitroglycerine-based explosives. The Royal Ordnance Factory at Bishopton, to the West of Glasgow, produced explosives and propellants from 1915 until it closed in 2002. The factory used gravity channels, effectively stainless steel guttering, to transport nitroglycerine in the open air. The guttering ran between the building where nitroglycerine was produced and the building where it was mixed with stabilising materials. If the nitroglycerine in the channel detonated, the damage was limited to a few dents in the metal channel.
As well as explosive applications, nitroglycerine has pharmaceutical application in the treatment of angina. Nitroglycerine is a stimulant that increases heartrate. For many, being in the presence of anything so unstable would be enough to get their hearts beating. People who worked with nitroglycerine at Bishopton could become mildly addicted to the physical effects of the fumes. I was told that retired employees asked former colleagues to provide them with a bottle of nitroglycerine so they could inhale the fumes. I leave you with the thought of a bottle of nitroglycerine on the mantlepiece …