By this time, the Industrial Revolution was increasing the speed of social change; buildings and civil works were proceeding apace, and breaking and moving rocks was becoming a big business. Tunnels, roads, and canals had to be built through rocky terrains, quartz and limestone had to be mined to meet the needs for aggregate and metals, and stone blocks were required for buildings. As mentioned previously, the deflagrating explosive black powder was powerful enough to heave boulders away from rock masses with existing fractures but not powerful enough to shatter unfractured rock—a more powerful explosive was needed. Detonating explosives that decomposed rapidly and created very high gas pressures had been made in laboratories in Switzerland and Italy in the late 1840s, but testing stopped because they were so dangerous. The time for high — energy explosives had come but there were many problems to be solved.
Before continuing the discussion of high-energy, detonating explosives we will compare the characteristics of black powder and nitroglycerin, which was the first commercial detonating explosive. The rates of reaction of the two explosives were 400 m/sec for black powder and 1,700 to 9,000 m/sec for nitroglycerin. In fact the rate of reaction of nitroglycerin is so fast that if a pipe 8.5 km long is filled with nitroglycerin and detonated by a blasting cap, the entire column would be converted into gas within one second (Peele 1941). Both explosives generated huge volumes of gas that were increased many times by the heat of reactions, which were up to 5,000°C. The result of these differences in practice was that black powder heaved and moved the rock; nitroglycerin also shattered it.
Nitroglycerin was calculated by Alfred Nobel to be more than 13 times as explosive as black powder when both heat and gas were taken into account (Eissler 1897).