The box, stored in the back room among the unclaimed freight, appeared to be leaking. Haven and Webster, the freight clerks sent to check it out, arrived with tools to pry open the crate. The ensuing blast shattered every window on the street, including some a half mile away, killing the two men and 13 others at work in surrounding buildings.
It was April of 1866, and the box, stored in the San Francisco office of Wells, Fargo & Co., was full of a liquid called “Nobel’s Blasting Oil,” which the Placer Herald of Auburn, California described, in a graphic news brief about the incident, as “a new explosive five times more powerful in its effects than [gun]powder.”
They weren’t the first deaths caused by the combustible liquid branded with Alfred Nobel’s name. Just two years earlier, the Swedish inventor’s younger brother, Emil, was killed in an explosion at the family factory in Stockholm. Explosives had become a vital tool of industry, used to mine everything from silver to salt, but blasting oil was volatile, and accidental detonations weren’t uncommon.
It was a deadly problem, but a year after the explosion in downtown San Francisco, Nobel had a solution. By mixing the oil with a stabilizing agent, he created the safest, most controllable explosive the world had ever seen. It was a divisive invention – years later, a French newspaper would credit Nobel with “finding ways to kill more people faster than ever before” – but one that has shaped society and helped extend the bounds of what humans can build: dynamite.
For nearly 1,000 years, the only widely-used explosive was black powder. A mixture of sulphur, charcoal, and potassium nitrate, black powder is what’s called a low explosive: it deflagrates, or burns, creating heat and gas. When that reaction is contained, it produces explosive energy – enough to propel a bullet from a gun (but not enough to burst the barrel), and, in high enough quantities, enough to blow through rock. In mining and engineering, powder was a passable, if imprecise, tool.
Then, in 1847, an Italian chemist named Ascanio Sobrero mixed glycerol with nitric and sulphuric acids, and created the first high explosive. Nitroglycerin doesn’t deflagrate: it detonates. When the molecular bonds between the liquid’s carbon, nitrogen, hydrogen and oxygen break, the molecules rearrange into gasses like dinitrogen and carbon monoxide. That kicks off a chain reaction that charges through the fuel, sending out a white-hot, supersonic wave with an explosive energy many times that of black powder. Any bump or jolt can trigger the reaction, making nitroglycerin incredibly unstable, to the extent that Sobrero didn’t believe his discovery had any practical uses.
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Nobel, a young scientist who’d cut his teeth at his father’s armament factories in Russia, producing sea mines used in the Crimean War, disagreed. Nitroglycerin oil could be used, he thought, if its detonation could be controlled and triggered from a safe distance. In 1863, he invented a remote detonator, which evolved into the blasting cap. It consisted of a small tin full of mercury fulminate, trailing a long fuse. Once the fuse burned, the mercury fulminate would erupt in flame, setting off the larger charges. In the next few years, 16 explosives factories with Nobel as part-owner were built in 14 countries, including the United States Blasting Oil Company. But even with the addition of a blasting cap, which allowed the user to time the explosion, nitroglycerin in oil form was tremendously dangerous, and every deadly accident turned public opinion against Nobel’s first invention.
To understand why dynamite was so revolutionary, says Larry Glenn Hill, a detonation physicist with Los Alamos National Laboratory’s High Explosive Science and Technology group, you have to understand the instability of its precursor.
“Detonation is a wondrous and highly specialized process, which involves the cooperation of two structures,” Hill explains. “The first is a shock wave, and the second is a burn wave.” A shock wave is a sharp rise in pressure, temperature, and density that travels at supersonic speeds. Picture it as the motion that occurs when you release a tightly coiled spring. As all that energy is expended, it produces heat, which is responsible for the fiery part of an explosion. “A detonation can be viewed as a burn-supported shock wave, or a shock-triggered burn wave; however one chooses to look at it. It is either and both.”
Under the right conditions, like being bumped around in a shipping crate or a rail car, nitroglycerin can develop stress waves that put the liquid into a state of tension. “This can cause the liquid to cavitate. That is, the boiling point is suddenly lowered to the point that a cloud of bubbles quickly forms,” Hill says. “But the next thing that happens is that a compressive wave, reflected from some boundary, comes along and collapses those bubbles.” The collapse produces extremely high temperatures, in the form of an instant shock wave, followed quickly by the burn. In other words, every time Nobel’s Blasting Oil moved, there was a risk it would spontaneously detonate. “It truly is Russian roulette,” Hill adds. “I’m not afraid of much, but liquid explosives make me nervous.”
Working in a laboratory on a barge on Lake Mälaren in Sweden, Nobel set out to stabilize the nitroglycerin by mixing it with something that would make it safe to move and handle. He tried brick dust, waste wood, and coal dust, letting the materials absorb nitroglycerin and then attempting to set them off with his blasting cap, before finally landing on diatomaceous earth, a dirt-like substance made of fossilized algae, in 1867. It works by turning the liquid nitroglycerin to a dough-like consistency, preventing bubbles from forming.
“Of course, this mechanism was not known in Nobel’s day,” Hill says. “He was just desperately trying things to save his reputation and his empire, and found that adding diatomaceous earth did the trick.”
At first, he marketed the new product, which came in sticks a few inches long, wrapped in heavy paper, as “Nobel’s Safety Blasting Powder.” He later changed the name to dynamite, after the Ancient Greek word for power.
Almost immediately, dynamite became an indispensable tool of engineering. The powerful explosiveness of nitroglycerin, coupled with Nobel’s blasting caps, could displace huge amounts of rock and earth in very little time, and the stability of this new form meant it could be easily transported to rugged construction sites. “Its introduction coincided with a lot of the railroads being pushed through uncharted territory, and they needed to get through large mountains,” says Henry Petroski, a professor of civil engineering and history at Duke University. “It was much more efficient than going up and down, and the dynamite was essential in blasting tunnels.”
In fact, some of the most monumental American projects of the late 19th and early 20th centuries couldn’t have been built without it. In the 1930s, as crews began construction on the Hoover Dam, “they had to divert the water,” Petroski, author of The Road Taken: The History and Future of America’s Infrastructure, says. “They used dynamite to drive tunnels through the canyon walls on either side of the river.” In the growing cities, the explosive was used to blast deep pits into the bedrock for skyscraper foundations. “Just about anywhere there was hard rock that needed to be excavated, they’d use dynamite.”
As dynamite-driven engineering projects were opening the earth’s surface to exploration, the invention was also revolutionizing the world below-ground. Mining operations couldn’t scale up to current production rates while they were dependent on the less powerful black powder, which only has the energy to blast through small sections of rock, and blasting oil, though many times more powerful, caused too many accidents and deaths. Dynamite offered the best of both worlds, and the mining industry grew to support a rapidly-industrializing world.
“If you can’t grow it, you have to mine it,” says Lee Fronapfel, mine manager of the Edgar Experimental Mine for the Colorado School of Mines. “People think that’s a cliché, but if it hasn’t been grown, I’ll bet my bottom dollar it was mined.”
Fronapfel points to contemporary society’s building materials: ore to produce concrete, aluminum, titanium and much more, all blasted from the earth with explosives. “We’re talking about the ability to make something with nothing by mining the raw materials, to produce something at the ground floor,” he says. There’s little about modern life that isn’t tied to the mining that dynamite made possible. “Without it, you wouldn’t have the amount of ore necessary to produce the amount of copper needed to even have electricity. You wouldn’t have the copper. Without dynamite, I think we’d barely be out of the stone age. I say that dynamite made our society.”
Nobel had made dynamite tame enough for the miner’s toolkit, but it wasn’t a perfect—or perfectly safe—solution.
“The dynamite would sweat, and if left it in one place for a long time, the nitroglycerin would tend to pool on the bottom,” Hill says. “In cold weather, the nitroglycerin would freeze, which desensitized it. Miners learned to carry the starting pieces (the pieces detonated with a blasting cap, which would initiate others in the chain) around in their socks to warm them up.”
Though much less volatile than pure nitroglycerin, dynamite would never be completely safe. In September of 1904, a trolley car in Boston hit a 50 lb box of dynamite which had fallen onto the tracks from a cart. The explosion killed 10 people in a blast radius more than 100 feet wide. In 1913, a sudden explosion of 340 tons of dynamite being transferred from a barge to a British steamship in Baltimore Harbor killed at least 50 people and wounded many more. In 1926, one of the biggest steam shovels in the world was destroyed, and its two operators killed, when it hit an old pocket of dynamite that failed to explode, was forgotten, or both – called a “coyote hole” – at a copper mine in Jerome, Arizona.
In an effort to continue to increase both its safety and its efficacy, Nobel spent the rest of his career improving on dynamite. “The biggest innovation was the addition of nitrocellulose as the solid material,” Hill says. Replacing the diatomaceous earth, Nobel increased the viscosity of the mix. The result was a new and improved, gelatinous dynamite.
Hill’s favorite historical tidbit about nitrocellulose represents how much the science behind the compound has played out in unexpected ways. “It was one of the first industrial plastics, and an early application was pool balls. They had the property that when two balls hit each other hard, they’d made a loud bang like a gunshot. At which point all the cowboys in the saloon would draw their guns.”
Here’s what that has to do with dynamite: the cracking sound when two nitrocellulose balls smacked together just right was actually a tiny explosion, because like nitroglycerin, nitrocellulose is combustible. Paired together, they created an even more powerful explosive with the stability of the original dynamite and a longer shelf life.
“Unlike the older dynamite, the nitroglycerin did not migrate through the matrix,” Hill says. In other words, it didn’t leak. The new stuff could also be used underwater, making it easier to tunnel through waterways and span rivers with dams.
Of course, it wasn’t just the engineering and mining industries that saw potential in high explosives. Nobel had also built a new instrument of war. It was first used as a weapon during the Franco-Prussian War of 1870, and between 1881 and 1885, Irish Republicans planted dynamite bombs at government and military targets in Great Britain, injuring upwards of 80 people with more than two dozen devices.
The American military devised its own weaponry based on Nobel’s invention. The first dynamite guns, named for artillery officer Edmund Zalinski, could launch an explosive projectile up to 5,000 yards. Zalinski guns were installed as coastal defense in San Francisco and New York. The U.S. army also commissioned 16 Sims-Dudley guns, a smaller dynamite-shooting weapon, which Theodore Roosevelt and his Rough Riders famously used to fire nitrocellulose gelatin-based shells during the siege of Santiago.
It was these usages that led a French newspaper, under the mistaken impression that Nobel had died in 1888 (it was actually his brother, Ludwig) to publish an obituary with the headline, “The Merchant of Death is Dead.”
In fact, Nobel was a pacifist – albeit, a bit of a twisted one. He believed his creation would prevent war by establishing mutually assured destruction, writing to a friend, “Perhaps my factories will put an end to war sooner than your congresses: on the day that two army corps can mutually annihilate each other in a second, all civilised nations will surely recoil with horror and disband their troops.”
By the time Nobel actually died, in 1896, he owned nearly 100 explosives and munitions factories, and dynamite had made him a fortune. He left most of it in trust, establishing the Nobel Prizes, given annually to scientists, doctors, writers, and those who work in the pursuit of peace.
More than 150 years after its invention, dynamite is still in use. It’s not as widespread; the mining industry, where the bottom dollar is king, has mostly transitioned to using cheaper, if less powerful, charges—typically a mixture of ammonium nitrate and diesel fuel—only using the occasional bit of dynamite when the extraction plan or rock makeup calls for a more forceful tool. The military has mastered other high explosives, which can be deployed with more surgical precision.
Dynamite is still the right tool for some tasks, says Fronapfel, but explosive technology has done what all technology eventually does: evolved. The real legacy of this world-changing invention—besides the Peace Prize named for its inventor—is the lithium in your cell phone battery and the silicon in your computer processor, both blasted out of mines. “Every bit of this comes from Nobel,” he says. “It’s all thanks to dynamite.” If you’re going to rebuild the world, you’ve got to start by blowing it up.
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