Jack Kelly writer
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BIG BANG
(Invention & Technology, Summer 2006)
On May 5, 1866, a reporter for the New York Times
confessed to “some little trepidation” as he headed off to
attend a demonstration at a rock quarry. A “professor” would
attempt to show that a liquid widely considered to be one of
the most dangerous substances on earth was in fact a
benign and useful explosive if properly handled. The
audience edged backward as the demonstrator poured some
of the oily fluid onto a rock and lit it with a match, causing it to
“burn like pitch, but not explode.” They cringed as he
dropped a vial from a height to show that it would not explode
accidentally. When he purposely set off a small quantity of
the liquid, all were startled by the “tremendous report.”
The “professor” was Alfred Nobel. The 33-year-old Swedish
engineer was promoting what the reporter described as “that
cheerful compound ordinarily recognized as nitro-glycerine.”
Nobel had begun to ship this “blasting oil” two years earlier. It
was the first new commercial explosive since engineers had
begun to use traditional gunpowder in mines in the
seventeenth century. Orders had poured in from all over the
world. America was the most promising market of all;
breakneck industrial growth, especially the spread of
railroads, had created an urgent need for an explosive that
could muscle through hard rock.
The nervousness of those attending the demonstration was
understandable. They knew that the previous November a
salesman’s sample of nitroglycerin had blown up outside a
Greenwich Village hotel, injuring 18 people and leaving a
four-foot crater in the pavement. By one account, “Every
window was shattered, the doors of the stores and dwellings
broken open and the chimneys thrown down.” They were
aware that in April a shipment to the California goldfields had
exploded while workers were unloading it in Panama. That
blast had killed 60 and wrecked half a million dollars’ worth of
property. The Times called it “one of the most terrible
accidents on record.” A few days later another shipment had
destroyed a San Francisco Wells Fargo office, smashing
windows for half a mile, a newspaper reported, and throwing
a human arm against “a third story window of the building
across the street.”
An alarmed Congress was considering legislation to restrict
shipment of the dangerous material and to make any
accident involving nitroglycerin a criminal, perhaps even
capital, offense. Railroads and steamship lines were refusing
to take it as freight; possession was as good as outlawed in
Britain, France, and Belgium. Nobel, his name reviled around
the world, had been asked to leave the New York hotel where
he was staying and to take his nitroglycerin samples with him.
As he scrambled to salvage his business, he received word
that his own factory near Hamburg, Germany, had blown up.
Nitroglycerin had been discovered in 1847 by an obscure
Italian chemist named Ascanio Sobrero. He had been treating
organic compounds with nitric acid, hoping to discover new
dyes and medicines. He found that he could make the acid
react with glycerin, a sweet, syrupy byproduct of soapmaking,
but only if he trickled in the glycerin very slowly, kept the
mixture cool, and added strong sulfuric acid. Then he
realized that the resulting oil, once separated from the acids,
was the most powerful explosive ever created. A trace of it
deposited on an anvil and struck with a hammer set off a
window-shaking concussion.
A drop was heated in a test tube,” he reported, “and
exploded with such violence that the glass splinters cut deep
into my face and hands, and hurt other people who were
some distance off in the room.” He judged the material, which
he called pyroglycerine, too dangerous to manufacture. It
was likely to remain a useless curiosity.
Not only was the chemical remarkably explosive, he noted,
but a drop of it on his tongue produced a violent headache.
Through the 1850s researchers in homeopathy would
prescribe a dilute form of nitroglycerin, which they called
glonoin oil, for headaches, on the principle of “like cures
like.” Medical investigators later found the chemical to be an
effective remedy for angina pectoris, for which it is still
prescribed today.
During the early 1860s Nobel, inspired by his father’s
experiments with explosives, began to look for a means to
turn nitro into a useful blasting agent. He found a way to
manufacture it with relative safety but then faced another
problem. Gunpowder had always been set off by a burning
fuse, but fire would not usually ignite nitroglycerin. How could
he detonate the material reliably?
In 1863 he hit on the idea of using a lesser explosion to
shock the nitro into detonation. “I therefore lay claim to the
idea so far as industrial use is concerned,” he wrote in his
patent application, “of contriving by administering a mere
initial impulse to develop an explosion in substances which,
exposed, can be brought into contact with burning bodies
without exploding.” The idea of an initiator, one explosive
setting off another, was the stroke of genius on which the
entire field of high explosives was founded.
At first Nobel used black powder (traditional gunpowder) as
the initiator. He placed a small container of it inside a charge
of nitroglycerin and exploded it with an ordinary fuse. Later
he switched to the more efficient mercury fulminate, which an
engineer could detonate with either a fuse or an electric
spark. The initiator was a kind of kindling, an easily
detonated intermediary between the spark or match and the
nitroglycerin.
Nitroglycerin’s innate sensitivity remained a vexing problem,
as did the fact that unless it was absolutely pure, it was
subject to unpredictable decomposition and spontaneous
explosion. Shipping, which subjected the liquid to jolting and
leakage, was a particular hazard.
Nobel, though shaken by the series of disasters, was aware
of the urgent need for an explosive more powerful than black
powder for mining and public works projects. He hurried back
to Europe to try to salvage his business.
Americans were not content to wait. Mighty works were afoot,
and if they required risk, so be it. One man who defied public
apprehension was George Mowbray, an English immigrant
trained as a druggist who had traveled to Titusville,
Pennsylvania, after Edwin Drake drilled the first oil well there
in 1859. Mowbray operated a refinery for a few years, then
turned his attention to nitroglycerin.
Oilmen had discovered that they could rejuvenate slow-
flowing or exhausted wells by detonating explosives inside,
fracturing nearby rock. In 1865 Edward A. L. Roberts used a
“torpedo” containing eight pounds of black powder for the
job. Two years later he switched to liquid nitroglycerin, which
gave much better results. He bought from Nobel’s American
licensees the exclusive rights to use nitro in oil wells.
The business of well “shooting” became a contentious one as
drillers tried to avoid the hefty fees—up to $1,300 per well—
that the Roberts monopoly charged. Moonlighters started
brewing nitroglycerin in out-of-the-way shacks. Since their
blasts shot telltale geysers of water or gravel high into the
air, they used the cover of darkness to avoid the Pinkerton
detectives Roberts hired to enforce his rights.
Of course, accidents accompanied this activity. Roberts’s
own factory was completely demolished in an explosion,
leaving a hole reported to be “large enough to contain a
dwelling house.” Men were often “blown to atoms,” leaving
remains that would barely fill a cigar box. “Nitroglycerine
literally tears its victims into shreds,” a contemporary
historian wrote. “It is quick as lightning and can’t be dodged.”
But while the accidents served as grim warnings, they also
graphically illustrated the extraordinary power of high
explosives, further boosting demand.
Mowbray left the oil fields in 1867 and at 53 took his process
for making nitroglycerin to northwest Massachusetts. There
he signed on with one of the most ambitious railway projects
of the day. Engineers were boring into Hoosac Mountain with
an eye to completing a tunnel almost 5 miles long and 22 feet
high. When finished, it would connect Boston to the
burgeoning economy of the West. But workers had been
digging off and on since 1851 and so far had penetrated
barely a mile into the mountain. The resistance of granite to
black-powder blasting had hampered the work and inflated
the cost of what was ridiculed as the “Great Bore.”
Knowing the difficulties of transporting nitroglycerin, Mowbray
set up his factory right at the western portal of the tunnel.
There he became the first American to manufacture
nitroglycerin on a commercial scale. A careful chemist, he
devised an efficient and relatively safe method that involved
dripping glycerin from glass jars into 116 stone pitchers of
acid that he set in ice-water troughs. He pumped cold
compressed air into the pitchers to stir the ingredients. When
the process was complete, workers poured the mixture into a
large vat of water, where the insoluble nitroglycerin settled
out. They drew it off and washed it several times with fresh
water to remove traces of acid. The result was a 450-pound
batch of fluid, “the color and consistency of olive oil,” as a
chemist described it. With this simple apparatus, Mowbray
eventually produced more than a million pounds of nitro-
glycerin, which he used at Hoosac and sold across the
country.
Workers carried the nitroglycerin—some 6,000 pounds of it a
month—into the tunnel and inserted canisters of it into the
drilled holes. Blasters set off the liquid by sending a charge
of static electricity down wires insulated with gutta-percha.
Equipped with the new explosive, which was generally
considered to be ten times as powerful as black powder, the
tunnelers chewed through the mountain at an accelerated
rate. Progress doubled to 51 feet a month. The tunnel was
finally completed in 1875, having cost $9.2 million and the
lives of 200 workers. It was the longest rail tunnel in America
at the time and one of the great engineering feats of the
century.
Mowbray knew that nitroglycerin froze at around 50 degrees
Fahrenheit, and it was generally believed that frozen nitro
was far more sensitive to shock than liquid. During the harsh
winter of 1867–68, canisters of the explosive were needed to
unblock an ice dam on the other side of the mountain.
Mowbray packed them in warm sawdust and threw a buffalo
robe over the cargo before sending C. P. Granger, an
engineer, to make the delivery. Descending the mountain in
deep snow, Granger’s sleigh overturned. By the time he
reassembled the nitroglycerin, he found it had frozen solid.
According to Mowbray, he “proceeded on his way, thinking a
heap but saying nothing.” When he arrived, he found that a
blasting cap could not detonate the frozen canisters. The
nitro became effective again only after it thawed.
The discovery was a boon to Mowbray’s business. From then
on, he stored and shipped nitroglycerin frozen. He devised
special railcars to carry it packed in ice, an attendant always
on hand to monitor the temperature. In 1877 he sent 100,000
pounds of nitroglycerin all the way to Manitoba for railroad
blasting. The shipment traveled by train, boat, two-wheeled
bull cart, and finally on men’s backs, all without incident.
Other daredevil manufacturers, some with little knowledge of
chemistry, were traveling the country during the 1870s
setting up nitroglycerin factories—often little more than
makeshift sheds—near work sites where the explosives were
needed. Engineers used liquid nitro extensively to drive the
Central Pacific rail line through the Sierra Nevada, cutting
months and millions of dollars from the job. Mowbray always
insisted that his “tri-nitro-glycerine” was different from Nobel’s
patented blasting oil, but they were the same substance (the
more formal chemical name is glyceryl trinitrate). Eventually
the American patent holders sued Mowbray and forced him
to give up the trade.
Any chemical explosion involves a sudden conversion of a
solid or liquid into a much larger volume of gas. The gas,
confined within the same space as the original material and
heated to extremes by the energy of the reaction, exerts
pressure on whatever surrounds it. This pressure, moving
outward in a shock wave, can bend and fracture rock, move
earth, or demolish a building.
Black powder, a physical mixture of sulfur and charcoal with
potassium nitrate, explodes through rapid combustion, a
chain reaction of fire racing through the powder as the
decomposing nitrate gushes oxygen. It is designated a low
explosive. In high explosives, the oxygen is contained inside
the very molecule itself, along with its fuel. Detonation is
propagated not by fire but by a shock wave that spreads
through the material at supersonic speed, shaking apart
each molecule and setting off the whole mass almost
instantaneously.
The temperature of a nitroglycerin explosion instantly
reaches 3,500 degrees centigrade, equal to the melting point
of a diamond. The hot gases generate a phenomenal
pressure, throwing out a shock wave in all directions at a
speed of 17,000 miles an hour (about eight times as fast as a
rifle bullet). Describing the difference between a black-
powder blast and the detonation of nitroglycerin, the historian
G. I. Brown wrote, “It is the difference between being bumped
into by a pedal cyclist or being knocked for six by an express
train.”
Speed is everything. A slice of cheesecake contains more
calories of potential energy than an equal portion of
nitroglycerin. But while the weight watcher spends an hour or
two in the gym working off a dietary indulgence, the explosive
releases all its energy with a suddenness that defies
imagination—barely a millionth of a second.
In spite of the success of Mowbray and others at putting pure
nitro-glycerin to work, the liquid’s drawbacks and dangers
remained. Alfred Nobel, in his second and more famous
insight, found a way to use and transport the volatile
explosive safely. He absorbed the oil in a diatomaceous earth
known as kieselguhr, which could hold three times its own
weight in nitroglycerin. He packed the resulting puttylike
substance into tubes and exploded it with the detonators he’d
already invented. Though not quite as powerful as pure
nitroglycerin, it was much safer and more convenient. He
referred to the new product as Nobel’s Safety Powder or by
its more common name, dynamite.
Patented in America in 1868, dynamite was one of the most
successful products ever to hit the market. Nobel’s factories
produced 11 tons of it in their first year of operation, 185
tons three years later, and by 1874 were turning out more
than 3,000 tons annually. So sought after was the product
that Nobel immediately began to struggle with a horde of
imitators bent on marketing their own versions, patent or no
patent.
“In the Old World,” his biographer Herta Pauli wrote, “the
story of high explosives would be one of inventions, high
finance, power politics, and wars. In the New World, it started
as one of patents, petty swindles, litigation, and accidents.”
Nobel licensed his American rights to a California firm called
the Giant Powder Company (powder continued as a general
term for explosives even though most of the new compounds
were not powders). The company set off the first dynamite in
the United States in 1867. Hard-rock miners and railroad
builders in the West eagerly embraced this more practical
explosive. In the East, gunpowder makers like the du Pont
family staunchly resisted the rival product. Mineworkers
imagined that because of its effectiveness, dynamite could
endanger their jobs. They sometimes threatened dynamite
salesmen with violence.
Nobel’s original product, known as “guhr dynamite,” was not
used for long in the United States. American chemists tried to
circumvent his patents by devising different ways to absorb
nitroglycerin. Instead of diluting it with inert clay, they
saturated chemicals that could themselves contribute
explosive power to the reaction. These “active dope”
products proved more powerful and more cost-effective than
Nobel’s invention. Known as “straight dynamite,” they quickly
came to dominate the U.S. market.
Some of the credit for their early development belongs to
James Howden, a chemist who had blasted rock with pure
nitroglycerin for the Central Pacific line. The California
Powder Works, a West Coast gunpowder company, hired
Howden to come up with a new product when they found that
Nobel’s Giant Powder was eating into their market. In 1872
he devised a nitroglycerin-based explosive that used
potassium nitrate, sugar, and other chemicals to absorb the
oil. He called the new product Hercules Powder.
The battle was joined, and dynamite formulas quickly began
to proliferate. Talliaferro P. Shaffner devised Porifera
Nitroleum by adding nitroglycerin to ground sponge, cotton
fiber, and sawdust treated with sodium nitrate. Vigorite,
another popular explosive, was a composition of nitroglycerin
with potassium chlorate, charcoal, dextrin, and sumac. An
English inventor named John Horsley created a patented
explosive by combining 4 parts nitroglycerin with some
potassium chlorate and 16 parts gall apples.
Nobel, indefatigable, soon made his own breakthrough, his
third major contribution to explosives technology. In 1875,
instead of saturating an absorbent with nitroglycerin, he
dissolved it in nitrocellulose. The result was a gelatin that not
only was waterproof but was even more powerful than
nitroglycerin alone and ideal for hard-rock blasting.
Although engineers welcomed explosives with greater
shattering power—“brisance” they called it—they also saw
that for many jobs, especially moving earth, they needed a
slower, heaving explosion. “Between black powder and Nobel’
s dynamite there was a great gap to be filled,” a publication
of the California Powder Works noted. To fill the gap, Egbert
Judson patented Judson Powder, which contained potassium
nitrate and sulfur along with anthracite coal and asphaltum
mixed with only 5 percent nitroglycerin. Many similar mixtures
joined the ranks of “graded” dynamites.
Hercules, Neptune, Ajax, Vulcan, Samson—explosives
makers scoured mythology to tout the potency of their
products. At first they avoided Nobel’s term, but before long
the word dynamite had become generic. Patent suits flew with
a frequency that warmed the hearts of lawyers but had little
long-term effect on the industry, which continued to expand
at an unprecedented pace through the rest of the nineteenth
century. With the expiration of the original patents in the
1880s, the price of the product fell from $1.75 to less than 50
cents a pound.
After warning for several years of the dire peril of high
explosives, black-powder makers reversed course and began
making dynamite themselves. Their marketing and technical
clout allowed them to jump into the business with both feet. In
1880 the du Ponts and a consortium of other powder makers
started a dynamite factory in Repauno, New Jersey. It soon
became the largest plant in the world, and by the turn of the
century the DuPont company controlled much of the
explosives industry in America.
Though marked by the occasional horrific accident, the
business became relatively safe. In the early days workers
tending the nitrification process sat on one-legged stools,
lest they doze off and let the reaction get out of control.
Because of their exposure to nitroglycerin, they suffered from
intense headaches when they first started on the job. After
about two weeks they became acclimated, and the pain
subsided. In order to avoid a recurrence of “NG head” after a
time away from the factory, workers sometimes took vials of
nitroglycerin with them on vacation and consumed minute
amounts to maintain their tolerance.
We think of dynamite explosions as spectacular events, but
they actually tend to be invisible. Engineers prefer to place
charges so that they perform useful work rather than send
debris flying, and a blast is over in an instant. So it’s easy to
forget the role these potent chemicals have played in
shaping our world. Their invention helped bring about, in the
late nineteenth and early twentieth centuries, a heroic age of
engineering.
Transportation was among the first beneficiaries of the new
technology. Before high explosives, travel in the United
States was far more difficult. Mountains presented formidable
obstacles to rail lines; rivers and ports were often obstructed;
roads remained primitive. Explosives vastly speeded the
digging of tunnels for trains and the clearing of shipping
channels. They economically shattered the rock needed for
roadbeds. Concrete highways required nearly a ton of
explosives per mile.
High explosives made possible public works on a scale never
before imagined. New York’s New Croton reservoir system,
completed in 1890, was carved with 7 million pounds of
dynamite. The excavations for the foundations of the city’s
proliferating skyscrapers were shaped by dynamite. Its
subway system, begun in 1900, gobbled up another 10
million pounds of explosives.
Progress on the Panama Canal, the most monumental
engineering project of the time, was speeded by use of more
than 61 million pounds of high explosives. One of the largest
blasts occurred in 1913, when President Woodrow Wilson
pushed a button to fire 80,000 pounds of dynamite and open
the dike that made the waterway continuous across the
isthmus.
Production of coal in the United States grew from 14 million
tons in 1860 to more than 500 million tons in 1910, and high
explosives did much of the heavy lifting. The mining of ore for
iron, steel, copper, and aluminum likewise benefited. The first
Portland cement mill in the United States opened in 1871,
and the concrete industry grew in parallel with the high
explosives that made its raw materials affordable. Ten million
pounds of dynamite went into the construction of Hoover
Dam, and Gutzon Borglum used 6,000 pounds of it to blast
the rough shape of George Washington’s face from Mount
Rushmore.
So eager were dynamite manufacturers to sell their product
during the early twentieth century that they even promoted it
to farmers as an all-purpose tool. Customers could blast
stumps or disintegrate boulders. They could blow open
ditches for drainage and loosen the soil before planting fruit
orchards. Farmers often built isolated “dynamite houses”
where they could store the explosive.
Though most of the early high explosives were based on
nitroglycerin, other formulations appeared. In 1871 the
English inventor Hermann Sprengel proposed using separate
oxidizing and combustible substances and mixing them
together just before use. This would overcome the cost and
danger of transporting materials that could explode
accidentally.
The idea was picked up in America, where Silas R. Divine
patented an explosive in 1881 that he called Rack-a-rock. It
consisted of paper or cloth bags of potassium chlorate
soaked with nitrobenzene shortly before use, then packed in
sealed copper cartridges. The most spectacular use of Divine’
s invention came four years later, when engineers used it to
pulverize Flood Rock, a barely visible but exceedingly
treacherous obstacle in Hell Gate Channel, which connects
New York’s East River with Long Island Sound. Rocky ledges
and unpredictable currents had brought ships to ruin there
for generations.
Gen. John Newton of the Army Corps of Engineers directed
that water be held back from Flood Rock with cofferdams
while shafts were driven 70 feet into it. Miners worked for
nine years honeycombing the rock with galleries, which they
charged with 240,000 pounds of Rack-a-rock and 42,000
pounds of dynamite. The explosion of the dynamite was to
act as an initiator and set off the less sensitive Rack-a-rock.
If it worked, it would be the most powerful man-made
explosion ever to occur on earth. On the morning of October
10, 1885, some 50,000 New Yorkers lined the shore and
crowded onto rooftops to watch. Newton’s 12-year-old
daughter, Mary, pushed a button to set off an electric
detonator. Onlookers heard “a deep rumble, then a dull
boom.” The ground gave a sickening shake. Then, across
nine acres of river, a mass of water and debris sprang up, at
points reaching 200 feet into the air. Flood Rock was
reduced to fragments. When the dredgers finished, the
channel’s perils were, The New York Times said, “smoothed
into an inviting smile.”
High explosives are like the genie that, released from its
lamp, can work both good and evil. The first decade of the
twenty-first century, with its suicide bombs and improvised
explosive devices, bears testimony to the destructive
potential of high explosives when used with malevolence. But
the impulse is hardly a new one. What were known as
dynamite “outrages” began soon after its invention.
Whereas black powder was bulky and required a substantial
milling operation to make, nitroglycerin was compact and
could be mixed up in a home laboratory from readily available
ingredients. Revolutionaries saw dynamite as the artillery of
the proletariat, a weapon that would allow workers to stand
up to the guns of the ruling class. As gunpowder had brought
down feudalism, they reasoned, dynamite would topple
capitalism. In 1881 Russian revolutionaries managed to
assassinate Czar Alexander II with a dynamite bomb after
seven unsuccessful attempts. Irish Fenians soon kicked off
their own dynamite campaign against their English
oppressors.
In America the decade of the 1880s was upset by enormous
economic inequalities, a flood of immigrants, and the colliding
aspirations of capital and labor. In response, some
revolutionaries adopted an almost mystical notion that
explosives could demolish intractable social conflict and bring
on a new age. Among them was Johann Most, a one-time
bookbinder and actor who had grown up in wrenching
poverty and immigrated to America from Germany in 1882.
Having accepted the seductive notion that “against tyrants all
means are justified,” Most became fixated on one means.
“Chemistry will liberate the laborer,” he declared. “To be sure
of success, revolutionaries should always have on hand
adequate quantities of nitroglycerine, dynamite, hand
grenades, and blasting charges.” Others took up the chant.
“Dynamite is the emancipator,” revolutionary publications
proclaimed. “Hurrah for dynamite!” Most took a job at a New
Jersey dynamite factory in order to learn the details of its
manufacture. He published The Science of Revolutionary
Warfare, which was sold at anarchist picnics. “In giving
dynamite to the downtrodden millions of the globe,” another
anarchist wrote, “science has done its best work.”
On May 3, 1886, a lockout at Chicago’s McCormick Reaper
works turned violent, and two unionists were killed. Labor
leaders called a protest rally for the next night in Haymarket
Square. Three thousand sympathizers showed up, but with
rain threatening, the crowd dwindled to a few hundred. As the
event was winding down, a force of about 180 policemen
appeared and ordered the radicals to disperse. A dynamite
bomb suddenly sailed through the air and exploded among
the police. Chaos followed, with police firing revolvers
indiscriminately into the crowd in what a Chicago Herald
reporter described as a scene of “wild carnage.”
Seven policemen died, along with an uncounted number of
citizens. The ensuing reaction, America’s first Red scare,
resulted in the death penalty for seven anarchist leaders,
several of whom had not even attended the rally.
Revolutionaries like Johann Most, sobered by the
experience, began to back away from their enthusiasm for
dynamite as a political cure-all. Explosions occasionally
punctuated Western labor disputes during the late
nineteenth and early twentieth centuries, but they never
became commonplace in this country.
Military men, on the other hand, were naturally and
continually interested in the potential of high explosives.
They had used black powder in mines and artillery shells
during the Civil War, but advanced fortifications and
increasingly heavy armor on battleships neutralized much of
its power. Dynamite, they thought, could be more potent if
hurled against an enemy’s defenses. The problem was that
the shock of being fired from a gun was itself enough to set
off the nitroglycerin before it left the muzzle.
During the 1880s the military turned to dynamite guns that
used the gentler force of air pressure to loft a shell a mile or
more. Their compressors, reservoirs, and valves made the
weapons bulky, though coastal guns that fired 600-pound
dynamite shells were installed in New Jersey. The Navy built
a ship called the Vesuvius that managed to fire a few
dynamite shells during the Spanish-American War, but with
little effect. The idea was soon abandoned.
Other chemicals, not quite so explosive as nitroglycerin but
better suited for military uses, were already being developed.
Engineers had to satisfy a laundry list of requirements for a
military explosive. It had to be cheap, based on readily
available raw materials, safe to handle, not easily detonated
by impact yet powerful when it did go off, stable,
noncorrosive, nontoxic, and easily melted so that it could be
poured into shells.
French researchers found a partial solution in trinitrophenol,
which had long been known as picric acid. They loaded it into
shells as early as 1885. But picric acid was corrosive to
metals and had other drawbacks. By the turn of the century
German scientists had developed trinitrotoluene (TNT). That
substance was based on an organic chemical, toluene, that
they were able to extract from coal tar. Soon TNT, more
stable and less corrosive than picric acid, though not as
powerful as nitroglycerin, became the most widely used
military explosive. Scientists came to regard it as a standard
for all explosives, even measuring the power of the atomic
bomb in terms of equivalent tons of TNT. During the
bombardments of World War I, TNT-filled shells rained an
unprecedented hell on front-line troops.
On a spring morning in April 1947 longshoremen were
loading fertilizer onto a ship in the port of Texas City, Texas,
when a blaze broke out onboard. While the fire brigade
struggled with the flames, the ship’s cargo exploded. The
blast, the worst industrial accident in the nation’s history,
killed 560 people and injured 3,000 more.
The incident put a spotlight on a chemical that was to take on
an important role in making the explosives industry safer and
more efficient—ammonium nitrate. Not at all sensitive alone,
ammonium nitrate can become a vigorous explosive when
mixed with fuels like petroleum, carbon, or powdered
aluminum.
Two Swedish inventors had patented the mixture of
ammonium nitrate and carbon as an explosive as far back as
1867. Alfred Nobel had used the salt during the 1870s to
create “extra” dynamite. Engineers had included it in what
were called “permissible” explosives for use in coal mines.
Because they exploded at a relatively low temperature, these
blasting agents were less likely to ignite the dust and
methane that collected in mines. Ammonium nitrate had also
been mixed with TNT during World War I to yield the potent
explosive amatol.
During the 1950s commercial blasters turned to mixtures of
ammonium nitrate with about 6 percent fuel oil, a product
known as ANFO. Like Sprengel explosives, the substance
could be mixed at the site of the blast. Because it required a
hefty shock to detonate, engineers carried Nobel’s detonator
principle one step further: They used an easily exploded
blasting cap to set off a booster charge. The booster, an
explosive of medium sensitivity, gave enough of a bang to
cause the ANFO to explode. The terrorist Timothy McVeigh
took advantage of the technology to create the four-ton
bomb that did such deadly damage in Oklahoma City in 1995.
ANFO and other explosives, collectively known as “blasting
agents,” were safer and cheaper than dynamite and more
effective for most earthmoving duties. They largely replaced
nitroglycerin-based agents during the second half of the
twentieth century. In 1957 dynamite still constituted 95
percent of the explosives used in the United States; today it
amounts to less than 2 percent. So thoroughly did the new
explosives take over that in 1974 DuPont, long the premier
high-explosives maker in America, announced that it was
phasing out its production of dynamite.
Explosives are still one of our most ubiquitous forms of
chemical technology, and they still remain largely hidden.
Every hour, around the clock, engineers detonate an
average of 628,000 pounds of high explosives in the United
States—5.5 billion pounds annually. About two-thirds of that
is used in the coal industry, with mining of metal ores and
quarrying accounting for much of the rest. A wide range of
different types of explosives are used for other applications,
from seismic exploration and firefighting to welding,
demolition, and logging.
Alfred Nobel was a gloomy idealist. He warned in 1892 of “a
new reign of terror … one seems to hear its hollow rumble in
the distance al-ready.” Yet he remained rightly convinced
that explosives were, in the final reckoning, a boon to
humanity and a pivotal contribution to the formation of our
modern world. His relatively simple inventions, the blasting
cap and dynamite, together with his acute business sense,
allowed him to amass untold wealth. At his death, in 1896 at
age 63, he left his fortune to prizes for those who advanced
the cause of peace or who made important contributions to
the sciences and the arts. The world takes explosives so
much for granted today that Nobel is much better known for
those prizes than for his world-changing inventions.
# # #
(Invention & Technology, Summer 2006)
On May 5, 1866, a reporter for the New York Times
confessed to “some little trepidation” as he headed off to
attend a demonstration at a rock quarry. A “professor” would
attempt to show that a liquid widely considered to be one of
the most dangerous substances on earth was in fact a
benign and useful explosive if properly handled. The
audience edged backward as the demonstrator poured some
of the oily fluid onto a rock and lit it with a match, causing it to
“burn like pitch, but not explode.” They cringed as he
dropped a vial from a height to show that it would not explode
accidentally. When he purposely set off a small quantity of
the liquid, all were startled by the “tremendous report.”
The “professor” was Alfred Nobel. The 33-year-old Swedish
engineer was promoting what the reporter described as “that
cheerful compound ordinarily recognized as nitro-glycerine.”
Nobel had begun to ship this “blasting oil” two years earlier. It
was the first new commercial explosive since engineers had
begun to use traditional gunpowder in mines in the
seventeenth century. Orders had poured in from all over the
world. America was the most promising market of all;
breakneck industrial growth, especially the spread of
railroads, had created an urgent need for an explosive that
could muscle through hard rock.
The nervousness of those attending the demonstration was
understandable. They knew that the previous November a
salesman’s sample of nitroglycerin had blown up outside a
Greenwich Village hotel, injuring 18 people and leaving a
four-foot crater in the pavement. By one account, “Every
window was shattered, the doors of the stores and dwellings
broken open and the chimneys thrown down.” They were
aware that in April a shipment to the California goldfields had
exploded while workers were unloading it in Panama. That
blast had killed 60 and wrecked half a million dollars’ worth of
property. The Times called it “one of the most terrible
accidents on record.” A few days later another shipment had
destroyed a San Francisco Wells Fargo office, smashing
windows for half a mile, a newspaper reported, and throwing
a human arm against “a third story window of the building
across the street.”
An alarmed Congress was considering legislation to restrict
shipment of the dangerous material and to make any
accident involving nitroglycerin a criminal, perhaps even
capital, offense. Railroads and steamship lines were refusing
to take it as freight; possession was as good as outlawed in
Britain, France, and Belgium. Nobel, his name reviled around
the world, had been asked to leave the New York hotel where
he was staying and to take his nitroglycerin samples with him.
As he scrambled to salvage his business, he received word
that his own factory near Hamburg, Germany, had blown up.
Nitroglycerin had been discovered in 1847 by an obscure
Italian chemist named Ascanio Sobrero. He had been treating
organic compounds with nitric acid, hoping to discover new
dyes and medicines. He found that he could make the acid
react with glycerin, a sweet, syrupy byproduct of soapmaking,
but only if he trickled in the glycerin very slowly, kept the
mixture cool, and added strong sulfuric acid. Then he
realized that the resulting oil, once separated from the acids,
was the most powerful explosive ever created. A trace of it
deposited on an anvil and struck with a hammer set off a
window-shaking concussion.
A drop was heated in a test tube,” he reported, “and
exploded with such violence that the glass splinters cut deep
into my face and hands, and hurt other people who were
some distance off in the room.” He judged the material, which
he called pyroglycerine, too dangerous to manufacture. It
was likely to remain a useless curiosity.
Not only was the chemical remarkably explosive, he noted,
but a drop of it on his tongue produced a violent headache.
Through the 1850s researchers in homeopathy would
prescribe a dilute form of nitroglycerin, which they called
glonoin oil, for headaches, on the principle of “like cures
like.” Medical investigators later found the chemical to be an
effective remedy for angina pectoris, for which it is still
prescribed today.
During the early 1860s Nobel, inspired by his father’s
experiments with explosives, began to look for a means to
turn nitro into a useful blasting agent. He found a way to
manufacture it with relative safety but then faced another
problem. Gunpowder had always been set off by a burning
fuse, but fire would not usually ignite nitroglycerin. How could
he detonate the material reliably?
In 1863 he hit on the idea of using a lesser explosion to
shock the nitro into detonation. “I therefore lay claim to the
idea so far as industrial use is concerned,” he wrote in his
patent application, “of contriving by administering a mere
initial impulse to develop an explosion in substances which,
exposed, can be brought into contact with burning bodies
without exploding.” The idea of an initiator, one explosive
setting off another, was the stroke of genius on which the
entire field of high explosives was founded.
At first Nobel used black powder (traditional gunpowder) as
the initiator. He placed a small container of it inside a charge
of nitroglycerin and exploded it with an ordinary fuse. Later
he switched to the more efficient mercury fulminate, which an
engineer could detonate with either a fuse or an electric
spark. The initiator was a kind of kindling, an easily
detonated intermediary between the spark or match and the
nitroglycerin.
Nitroglycerin’s innate sensitivity remained a vexing problem,
as did the fact that unless it was absolutely pure, it was
subject to unpredictable decomposition and spontaneous
explosion. Shipping, which subjected the liquid to jolting and
leakage, was a particular hazard.
Nobel, though shaken by the series of disasters, was aware
of the urgent need for an explosive more powerful than black
powder for mining and public works projects. He hurried back
to Europe to try to salvage his business.
Americans were not content to wait. Mighty works were afoot,
and if they required risk, so be it. One man who defied public
apprehension was George Mowbray, an English immigrant
trained as a druggist who had traveled to Titusville,
Pennsylvania, after Edwin Drake drilled the first oil well there
in 1859. Mowbray operated a refinery for a few years, then
turned his attention to nitroglycerin.
Oilmen had discovered that they could rejuvenate slow-
flowing or exhausted wells by detonating explosives inside,
fracturing nearby rock. In 1865 Edward A. L. Roberts used a
“torpedo” containing eight pounds of black powder for the
job. Two years later he switched to liquid nitroglycerin, which
gave much better results. He bought from Nobel’s American
licensees the exclusive rights to use nitro in oil wells.
The business of well “shooting” became a contentious one as
drillers tried to avoid the hefty fees—up to $1,300 per well—
that the Roberts monopoly charged. Moonlighters started
brewing nitroglycerin in out-of-the-way shacks. Since their
blasts shot telltale geysers of water or gravel high into the
air, they used the cover of darkness to avoid the Pinkerton
detectives Roberts hired to enforce his rights.
Of course, accidents accompanied this activity. Roberts’s
own factory was completely demolished in an explosion,
leaving a hole reported to be “large enough to contain a
dwelling house.” Men were often “blown to atoms,” leaving
remains that would barely fill a cigar box. “Nitroglycerine
literally tears its victims into shreds,” a contemporary
historian wrote. “It is quick as lightning and can’t be dodged.”
But while the accidents served as grim warnings, they also
graphically illustrated the extraordinary power of high
explosives, further boosting demand.
Mowbray left the oil fields in 1867 and at 53 took his process
for making nitroglycerin to northwest Massachusetts. There
he signed on with one of the most ambitious railway projects
of the day. Engineers were boring into Hoosac Mountain with
an eye to completing a tunnel almost 5 miles long and 22 feet
high. When finished, it would connect Boston to the
burgeoning economy of the West. But workers had been
digging off and on since 1851 and so far had penetrated
barely a mile into the mountain. The resistance of granite to
black-powder blasting had hampered the work and inflated
the cost of what was ridiculed as the “Great Bore.”
Knowing the difficulties of transporting nitroglycerin, Mowbray
set up his factory right at the western portal of the tunnel.
There he became the first American to manufacture
nitroglycerin on a commercial scale. A careful chemist, he
devised an efficient and relatively safe method that involved
dripping glycerin from glass jars into 116 stone pitchers of
acid that he set in ice-water troughs. He pumped cold
compressed air into the pitchers to stir the ingredients. When
the process was complete, workers poured the mixture into a
large vat of water, where the insoluble nitroglycerin settled
out. They drew it off and washed it several times with fresh
water to remove traces of acid. The result was a 450-pound
batch of fluid, “the color and consistency of olive oil,” as a
chemist described it. With this simple apparatus, Mowbray
eventually produced more than a million pounds of nitro-
glycerin, which he used at Hoosac and sold across the
country.
Workers carried the nitroglycerin—some 6,000 pounds of it a
month—into the tunnel and inserted canisters of it into the
drilled holes. Blasters set off the liquid by sending a charge
of static electricity down wires insulated with gutta-percha.
Equipped with the new explosive, which was generally
considered to be ten times as powerful as black powder, the
tunnelers chewed through the mountain at an accelerated
rate. Progress doubled to 51 feet a month. The tunnel was
finally completed in 1875, having cost $9.2 million and the
lives of 200 workers. It was the longest rail tunnel in America
at the time and one of the great engineering feats of the
century.
Mowbray knew that nitroglycerin froze at around 50 degrees
Fahrenheit, and it was generally believed that frozen nitro
was far more sensitive to shock than liquid. During the harsh
winter of 1867–68, canisters of the explosive were needed to
unblock an ice dam on the other side of the mountain.
Mowbray packed them in warm sawdust and threw a buffalo
robe over the cargo before sending C. P. Granger, an
engineer, to make the delivery. Descending the mountain in
deep snow, Granger’s sleigh overturned. By the time he
reassembled the nitroglycerin, he found it had frozen solid.
According to Mowbray, he “proceeded on his way, thinking a
heap but saying nothing.” When he arrived, he found that a
blasting cap could not detonate the frozen canisters. The
nitro became effective again only after it thawed.
The discovery was a boon to Mowbray’s business. From then
on, he stored and shipped nitroglycerin frozen. He devised
special railcars to carry it packed in ice, an attendant always
on hand to monitor the temperature. In 1877 he sent 100,000
pounds of nitroglycerin all the way to Manitoba for railroad
blasting. The shipment traveled by train, boat, two-wheeled
bull cart, and finally on men’s backs, all without incident.
Other daredevil manufacturers, some with little knowledge of
chemistry, were traveling the country during the 1870s
setting up nitroglycerin factories—often little more than
makeshift sheds—near work sites where the explosives were
needed. Engineers used liquid nitro extensively to drive the
Central Pacific rail line through the Sierra Nevada, cutting
months and millions of dollars from the job. Mowbray always
insisted that his “tri-nitro-glycerine” was different from Nobel’s
patented blasting oil, but they were the same substance (the
more formal chemical name is glyceryl trinitrate). Eventually
the American patent holders sued Mowbray and forced him
to give up the trade.
Any chemical explosion involves a sudden conversion of a
solid or liquid into a much larger volume of gas. The gas,
confined within the same space as the original material and
heated to extremes by the energy of the reaction, exerts
pressure on whatever surrounds it. This pressure, moving
outward in a shock wave, can bend and fracture rock, move
earth, or demolish a building.
Black powder, a physical mixture of sulfur and charcoal with
potassium nitrate, explodes through rapid combustion, a
chain reaction of fire racing through the powder as the
decomposing nitrate gushes oxygen. It is designated a low
explosive. In high explosives, the oxygen is contained inside
the very molecule itself, along with its fuel. Detonation is
propagated not by fire but by a shock wave that spreads
through the material at supersonic speed, shaking apart
each molecule and setting off the whole mass almost
instantaneously.
The temperature of a nitroglycerin explosion instantly
reaches 3,500 degrees centigrade, equal to the melting point
of a diamond. The hot gases generate a phenomenal
pressure, throwing out a shock wave in all directions at a
speed of 17,000 miles an hour (about eight times as fast as a
rifle bullet). Describing the difference between a black-
powder blast and the detonation of nitroglycerin, the historian
G. I. Brown wrote, “It is the difference between being bumped
into by a pedal cyclist or being knocked for six by an express
train.”
Speed is everything. A slice of cheesecake contains more
calories of potential energy than an equal portion of
nitroglycerin. But while the weight watcher spends an hour or
two in the gym working off a dietary indulgence, the explosive
releases all its energy with a suddenness that defies
imagination—barely a millionth of a second.
In spite of the success of Mowbray and others at putting pure
nitro-glycerin to work, the liquid’s drawbacks and dangers
remained. Alfred Nobel, in his second and more famous
insight, found a way to use and transport the volatile
explosive safely. He absorbed the oil in a diatomaceous earth
known as kieselguhr, which could hold three times its own
weight in nitroglycerin. He packed the resulting puttylike
substance into tubes and exploded it with the detonators he’d
already invented. Though not quite as powerful as pure
nitroglycerin, it was much safer and more convenient. He
referred to the new product as Nobel’s Safety Powder or by
its more common name, dynamite.
Patented in America in 1868, dynamite was one of the most
successful products ever to hit the market. Nobel’s factories
produced 11 tons of it in their first year of operation, 185
tons three years later, and by 1874 were turning out more
than 3,000 tons annually. So sought after was the product
that Nobel immediately began to struggle with a horde of
imitators bent on marketing their own versions, patent or no
patent.
“In the Old World,” his biographer Herta Pauli wrote, “the
story of high explosives would be one of inventions, high
finance, power politics, and wars. In the New World, it started
as one of patents, petty swindles, litigation, and accidents.”
Nobel licensed his American rights to a California firm called
the Giant Powder Company (powder continued as a general
term for explosives even though most of the new compounds
were not powders). The company set off the first dynamite in
the United States in 1867. Hard-rock miners and railroad
builders in the West eagerly embraced this more practical
explosive. In the East, gunpowder makers like the du Pont
family staunchly resisted the rival product. Mineworkers
imagined that because of its effectiveness, dynamite could
endanger their jobs. They sometimes threatened dynamite
salesmen with violence.
Nobel’s original product, known as “guhr dynamite,” was not
used for long in the United States. American chemists tried to
circumvent his patents by devising different ways to absorb
nitroglycerin. Instead of diluting it with inert clay, they
saturated chemicals that could themselves contribute
explosive power to the reaction. These “active dope”
products proved more powerful and more cost-effective than
Nobel’s invention. Known as “straight dynamite,” they quickly
came to dominate the U.S. market.
Some of the credit for their early development belongs to
James Howden, a chemist who had blasted rock with pure
nitroglycerin for the Central Pacific line. The California
Powder Works, a West Coast gunpowder company, hired
Howden to come up with a new product when they found that
Nobel’s Giant Powder was eating into their market. In 1872
he devised a nitroglycerin-based explosive that used
potassium nitrate, sugar, and other chemicals to absorb the
oil. He called the new product Hercules Powder.
The battle was joined, and dynamite formulas quickly began
to proliferate. Talliaferro P. Shaffner devised Porifera
Nitroleum by adding nitroglycerin to ground sponge, cotton
fiber, and sawdust treated with sodium nitrate. Vigorite,
another popular explosive, was a composition of nitroglycerin
with potassium chlorate, charcoal, dextrin, and sumac. An
English inventor named John Horsley created a patented
explosive by combining 4 parts nitroglycerin with some
potassium chlorate and 16 parts gall apples.
Nobel, indefatigable, soon made his own breakthrough, his
third major contribution to explosives technology. In 1875,
instead of saturating an absorbent with nitroglycerin, he
dissolved it in nitrocellulose. The result was a gelatin that not
only was waterproof but was even more powerful than
nitroglycerin alone and ideal for hard-rock blasting.
Although engineers welcomed explosives with greater
shattering power—“brisance” they called it—they also saw
that for many jobs, especially moving earth, they needed a
slower, heaving explosion. “Between black powder and Nobel’
s dynamite there was a great gap to be filled,” a publication
of the California Powder Works noted. To fill the gap, Egbert
Judson patented Judson Powder, which contained potassium
nitrate and sulfur along with anthracite coal and asphaltum
mixed with only 5 percent nitroglycerin. Many similar mixtures
joined the ranks of “graded” dynamites.
Hercules, Neptune, Ajax, Vulcan, Samson—explosives
makers scoured mythology to tout the potency of their
products. At first they avoided Nobel’s term, but before long
the word dynamite had become generic. Patent suits flew with
a frequency that warmed the hearts of lawyers but had little
long-term effect on the industry, which continued to expand
at an unprecedented pace through the rest of the nineteenth
century. With the expiration of the original patents in the
1880s, the price of the product fell from $1.75 to less than 50
cents a pound.
After warning for several years of the dire peril of high
explosives, black-powder makers reversed course and began
making dynamite themselves. Their marketing and technical
clout allowed them to jump into the business with both feet. In
1880 the du Ponts and a consortium of other powder makers
started a dynamite factory in Repauno, New Jersey. It soon
became the largest plant in the world, and by the turn of the
century the DuPont company controlled much of the
explosives industry in America.
Though marked by the occasional horrific accident, the
business became relatively safe. In the early days workers
tending the nitrification process sat on one-legged stools,
lest they doze off and let the reaction get out of control.
Because of their exposure to nitroglycerin, they suffered from
intense headaches when they first started on the job. After
about two weeks they became acclimated, and the pain
subsided. In order to avoid a recurrence of “NG head” after a
time away from the factory, workers sometimes took vials of
nitroglycerin with them on vacation and consumed minute
amounts to maintain their tolerance.
We think of dynamite explosions as spectacular events, but
they actually tend to be invisible. Engineers prefer to place
charges so that they perform useful work rather than send
debris flying, and a blast is over in an instant. So it’s easy to
forget the role these potent chemicals have played in
shaping our world. Their invention helped bring about, in the
late nineteenth and early twentieth centuries, a heroic age of
engineering.
Transportation was among the first beneficiaries of the new
technology. Before high explosives, travel in the United
States was far more difficult. Mountains presented formidable
obstacles to rail lines; rivers and ports were often obstructed;
roads remained primitive. Explosives vastly speeded the
digging of tunnels for trains and the clearing of shipping
channels. They economically shattered the rock needed for
roadbeds. Concrete highways required nearly a ton of
explosives per mile.
High explosives made possible public works on a scale never
before imagined. New York’s New Croton reservoir system,
completed in 1890, was carved with 7 million pounds of
dynamite. The excavations for the foundations of the city’s
proliferating skyscrapers were shaped by dynamite. Its
subway system, begun in 1900, gobbled up another 10
million pounds of explosives.
Progress on the Panama Canal, the most monumental
engineering project of the time, was speeded by use of more
than 61 million pounds of high explosives. One of the largest
blasts occurred in 1913, when President Woodrow Wilson
pushed a button to fire 80,000 pounds of dynamite and open
the dike that made the waterway continuous across the
isthmus.
Production of coal in the United States grew from 14 million
tons in 1860 to more than 500 million tons in 1910, and high
explosives did much of the heavy lifting. The mining of ore for
iron, steel, copper, and aluminum likewise benefited. The first
Portland cement mill in the United States opened in 1871,
and the concrete industry grew in parallel with the high
explosives that made its raw materials affordable. Ten million
pounds of dynamite went into the construction of Hoover
Dam, and Gutzon Borglum used 6,000 pounds of it to blast
the rough shape of George Washington’s face from Mount
Rushmore.
So eager were dynamite manufacturers to sell their product
during the early twentieth century that they even promoted it
to farmers as an all-purpose tool. Customers could blast
stumps or disintegrate boulders. They could blow open
ditches for drainage and loosen the soil before planting fruit
orchards. Farmers often built isolated “dynamite houses”
where they could store the explosive.
Though most of the early high explosives were based on
nitroglycerin, other formulations appeared. In 1871 the
English inventor Hermann Sprengel proposed using separate
oxidizing and combustible substances and mixing them
together just before use. This would overcome the cost and
danger of transporting materials that could explode
accidentally.
The idea was picked up in America, where Silas R. Divine
patented an explosive in 1881 that he called Rack-a-rock. It
consisted of paper or cloth bags of potassium chlorate
soaked with nitrobenzene shortly before use, then packed in
sealed copper cartridges. The most spectacular use of Divine’
s invention came four years later, when engineers used it to
pulverize Flood Rock, a barely visible but exceedingly
treacherous obstacle in Hell Gate Channel, which connects
New York’s East River with Long Island Sound. Rocky ledges
and unpredictable currents had brought ships to ruin there
for generations.
Gen. John Newton of the Army Corps of Engineers directed
that water be held back from Flood Rock with cofferdams
while shafts were driven 70 feet into it. Miners worked for
nine years honeycombing the rock with galleries, which they
charged with 240,000 pounds of Rack-a-rock and 42,000
pounds of dynamite. The explosion of the dynamite was to
act as an initiator and set off the less sensitive Rack-a-rock.
If it worked, it would be the most powerful man-made
explosion ever to occur on earth. On the morning of October
10, 1885, some 50,000 New Yorkers lined the shore and
crowded onto rooftops to watch. Newton’s 12-year-old
daughter, Mary, pushed a button to set off an electric
detonator. Onlookers heard “a deep rumble, then a dull
boom.” The ground gave a sickening shake. Then, across
nine acres of river, a mass of water and debris sprang up, at
points reaching 200 feet into the air. Flood Rock was
reduced to fragments. When the dredgers finished, the
channel’s perils were, The New York Times said, “smoothed
into an inviting smile.”
High explosives are like the genie that, released from its
lamp, can work both good and evil. The first decade of the
twenty-first century, with its suicide bombs and improvised
explosive devices, bears testimony to the destructive
potential of high explosives when used with malevolence. But
the impulse is hardly a new one. What were known as
dynamite “outrages” began soon after its invention.
Whereas black powder was bulky and required a substantial
milling operation to make, nitroglycerin was compact and
could be mixed up in a home laboratory from readily available
ingredients. Revolutionaries saw dynamite as the artillery of
the proletariat, a weapon that would allow workers to stand
up to the guns of the ruling class. As gunpowder had brought
down feudalism, they reasoned, dynamite would topple
capitalism. In 1881 Russian revolutionaries managed to
assassinate Czar Alexander II with a dynamite bomb after
seven unsuccessful attempts. Irish Fenians soon kicked off
their own dynamite campaign against their English
oppressors.
In America the decade of the 1880s was upset by enormous
economic inequalities, a flood of immigrants, and the colliding
aspirations of capital and labor. In response, some
revolutionaries adopted an almost mystical notion that
explosives could demolish intractable social conflict and bring
on a new age. Among them was Johann Most, a one-time
bookbinder and actor who had grown up in wrenching
poverty and immigrated to America from Germany in 1882.
Having accepted the seductive notion that “against tyrants all
means are justified,” Most became fixated on one means.
“Chemistry will liberate the laborer,” he declared. “To be sure
of success, revolutionaries should always have on hand
adequate quantities of nitroglycerine, dynamite, hand
grenades, and blasting charges.” Others took up the chant.
“Dynamite is the emancipator,” revolutionary publications
proclaimed. “Hurrah for dynamite!” Most took a job at a New
Jersey dynamite factory in order to learn the details of its
manufacture. He published The Science of Revolutionary
Warfare, which was sold at anarchist picnics. “In giving
dynamite to the downtrodden millions of the globe,” another
anarchist wrote, “science has done its best work.”
On May 3, 1886, a lockout at Chicago’s McCormick Reaper
works turned violent, and two unionists were killed. Labor
leaders called a protest rally for the next night in Haymarket
Square. Three thousand sympathizers showed up, but with
rain threatening, the crowd dwindled to a few hundred. As the
event was winding down, a force of about 180 policemen
appeared and ordered the radicals to disperse. A dynamite
bomb suddenly sailed through the air and exploded among
the police. Chaos followed, with police firing revolvers
indiscriminately into the crowd in what a Chicago Herald
reporter described as a scene of “wild carnage.”
Seven policemen died, along with an uncounted number of
citizens. The ensuing reaction, America’s first Red scare,
resulted in the death penalty for seven anarchist leaders,
several of whom had not even attended the rally.
Revolutionaries like Johann Most, sobered by the
experience, began to back away from their enthusiasm for
dynamite as a political cure-all. Explosions occasionally
punctuated Western labor disputes during the late
nineteenth and early twentieth centuries, but they never
became commonplace in this country.
Military men, on the other hand, were naturally and
continually interested in the potential of high explosives.
They had used black powder in mines and artillery shells
during the Civil War, but advanced fortifications and
increasingly heavy armor on battleships neutralized much of
its power. Dynamite, they thought, could be more potent if
hurled against an enemy’s defenses. The problem was that
the shock of being fired from a gun was itself enough to set
off the nitroglycerin before it left the muzzle.
During the 1880s the military turned to dynamite guns that
used the gentler force of air pressure to loft a shell a mile or
more. Their compressors, reservoirs, and valves made the
weapons bulky, though coastal guns that fired 600-pound
dynamite shells were installed in New Jersey. The Navy built
a ship called the Vesuvius that managed to fire a few
dynamite shells during the Spanish-American War, but with
little effect. The idea was soon abandoned.
Other chemicals, not quite so explosive as nitroglycerin but
better suited for military uses, were already being developed.
Engineers had to satisfy a laundry list of requirements for a
military explosive. It had to be cheap, based on readily
available raw materials, safe to handle, not easily detonated
by impact yet powerful when it did go off, stable,
noncorrosive, nontoxic, and easily melted so that it could be
poured into shells.
French researchers found a partial solution in trinitrophenol,
which had long been known as picric acid. They loaded it into
shells as early as 1885. But picric acid was corrosive to
metals and had other drawbacks. By the turn of the century
German scientists had developed trinitrotoluene (TNT). That
substance was based on an organic chemical, toluene, that
they were able to extract from coal tar. Soon TNT, more
stable and less corrosive than picric acid, though not as
powerful as nitroglycerin, became the most widely used
military explosive. Scientists came to regard it as a standard
for all explosives, even measuring the power of the atomic
bomb in terms of equivalent tons of TNT. During the
bombardments of World War I, TNT-filled shells rained an
unprecedented hell on front-line troops.
On a spring morning in April 1947 longshoremen were
loading fertilizer onto a ship in the port of Texas City, Texas,
when a blaze broke out onboard. While the fire brigade
struggled with the flames, the ship’s cargo exploded. The
blast, the worst industrial accident in the nation’s history,
killed 560 people and injured 3,000 more.
The incident put a spotlight on a chemical that was to take on
an important role in making the explosives industry safer and
more efficient—ammonium nitrate. Not at all sensitive alone,
ammonium nitrate can become a vigorous explosive when
mixed with fuels like petroleum, carbon, or powdered
aluminum.
Two Swedish inventors had patented the mixture of
ammonium nitrate and carbon as an explosive as far back as
1867. Alfred Nobel had used the salt during the 1870s to
create “extra” dynamite. Engineers had included it in what
were called “permissible” explosives for use in coal mines.
Because they exploded at a relatively low temperature, these
blasting agents were less likely to ignite the dust and
methane that collected in mines. Ammonium nitrate had also
been mixed with TNT during World War I to yield the potent
explosive amatol.
During the 1950s commercial blasters turned to mixtures of
ammonium nitrate with about 6 percent fuel oil, a product
known as ANFO. Like Sprengel explosives, the substance
could be mixed at the site of the blast. Because it required a
hefty shock to detonate, engineers carried Nobel’s detonator
principle one step further: They used an easily exploded
blasting cap to set off a booster charge. The booster, an
explosive of medium sensitivity, gave enough of a bang to
cause the ANFO to explode. The terrorist Timothy McVeigh
took advantage of the technology to create the four-ton
bomb that did such deadly damage in Oklahoma City in 1995.
ANFO and other explosives, collectively known as “blasting
agents,” were safer and cheaper than dynamite and more
effective for most earthmoving duties. They largely replaced
nitroglycerin-based agents during the second half of the
twentieth century. In 1957 dynamite still constituted 95
percent of the explosives used in the United States; today it
amounts to less than 2 percent. So thoroughly did the new
explosives take over that in 1974 DuPont, long the premier
high-explosives maker in America, announced that it was
phasing out its production of dynamite.
Explosives are still one of our most ubiquitous forms of
chemical technology, and they still remain largely hidden.
Every hour, around the clock, engineers detonate an
average of 628,000 pounds of high explosives in the United
States—5.5 billion pounds annually. About two-thirds of that
is used in the coal industry, with mining of metal ores and
quarrying accounting for much of the rest. A wide range of
different types of explosives are used for other applications,
from seismic exploration and firefighting to welding,
demolition, and logging.
Alfred Nobel was a gloomy idealist. He warned in 1892 of “a
new reign of terror … one seems to hear its hollow rumble in
the distance al-ready.” Yet he remained rightly convinced
that explosives were, in the final reckoning, a boon to
humanity and a pivotal contribution to the formation of our
modern world. His relatively simple inventions, the blasting
cap and dynamite, together with his acute business sense,
allowed him to amass untold wealth. At his death, in 1896 at
age 63, he left his fortune to prizes for those who advanced
the cause of peace or who made important contributions to
the sciences and the arts. The world takes explosives so
much for granted today that Nobel is much better known for
those prizes than for his world-changing inventions.
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