Photo of the Day

Jan. 16, 1919: At approximately 12:40 p.m. on the previous day, the North End was shaken by a terrific explosion caused by the bursting of a giant tank at the Purity Distilling Co. on Commercial Street. This is a view of the aftermath looking north across North End Park. The great molasses tank was located in the center of this picture. Sections of the metal may be seen at the extreme left and right in the picture. Twenty-one people perished, including two 10-year-olds, Pasquale Iantosca and Maria Distasio, who were collecting firewood near the molasses tank while home from school for lunch. Photo: BOSTON GLOBE ARCHIVE


Waist Deep, Covered the Street and Swirled and Bubbled about the Wreckage . .?

?Residents in Boston’s North End will tell you that on a hot summer day you can still catch a whiff of molasses. And that would make sense because the entire neighbourhood was overrun with molasses. One January day in 1919, a large tank of molasses burst open sending waves of sweet, sticky brown liquid crashing through the streets. Buildings collapsed. Twenty one people were killed. But for nearly 100 years the great molasses flood has remained a great mystery. How on a cold winter day could all that molasses move so quickly and caused so much damage?

The rupture of a giant molasses tank in Boston just after the First World War caused devastation and led to the longest legal case in the city?s history.

In what was probably the most bizarre disaster in United States’ history, a storage tank burst on Boston’s waterfront releasing over two million gallons of molasses in a 50 ft-high, 160 ft-wide wave that raced through the city’s north end at 35mph destroying everything it touched.

A?Boston Post?report at the time described it as?”molasses, waist deep, covered the street and swirled and bubbled about the wreckage . . . only an upheaval, a thrashing about in the sticky mass, showed where any life was.” People, horses, everything just struggled to survive and died. It’s extraordinary.

There was a group of men who were in a firehouse a short ways away from the molasses tank. The initial wave smashed against the firehouse and pushed it almost entirely off its foundation. Then the upper floors of the firehouse crashed down on them. They were on the first floor and they were trapped there for hours waiting for people to be able to rescue them because they were all pinned in place.

In Boston’s North End, a 50-foot-tall tank holding 2.3 million gallons of molasses burst, unleashing a deadly wave that rose nearly 25 feet high at one point. The destructive flood threw people and horses about, smashed buildings, and even damaged the steel supports of an elevated railway. Rescuers had to wade through knee-deep molasses and sticky debris to reach survivors. Twenty-one people died in the disaster, another 150 were injured, and the cleanup lasted for weeks. The cause of the failure was determined to be faulty construction and poor maintenance.

The ?Great Molasses Flood? tore through the city’s North End and deposited so much gooey residue that locals claimed they could still smell the molasses on warm days decades later.

For the first 30 to 60 seconds or so, that wave would have moved a lot like a tsunami, if you could imagine that. In that moment, what mattered about the molasses was its weight and heavy density. So, for that initial minute, you just have this massive wave of heavy fluid that’s crashing through everything. After that first minute or so, that’s when the fact that it’s molasses, and molasses is incredibly viscous, so it’s really thick and it likes to try to resist flow, that’s when that starts coming into play. Then you go from being a sort of tsunami to being like a seeping. It’s a seamless transition between those, but the longer you go after that first minute the more the viscosity of the molasses matters and the more it’s going to kind of seep through the neighbourhood and creep.

Jan. 16, 1919: The gooey molasses formed a tidal wave that reached a depth of 15 feet and in places was 100 yards wide over a two block area.

Jan. 20, 1919: Welders carefully began cutting up the molasses tank with torches in the search for bodies. Even though firemen constantly sprayed water upon the twisted wreckage, it wasn’t until the City of Boston ordered powerful streams from the city fireboat that the molasses began to disappear. The salt water of the harbor “cut” the molasses and eventually the welders could see the structure of the original tank. Photo: BOSTON GLOBE ARCHIVE

The wave killed young Pasquale Iantosca, smashing a railroad car into the ten-year-old. It pinned Walter Merrithew, a railroad clerk on the Commercial Street wharf, against the wall of a freight shed, his feet 3 ft off the floor. He hung there as he watched a horse drowning nearby. The wave broke steel girders of the Boston Elevated Railway, almost swept a train off its tracks, knocked buildings off their foundations, and toppled electrical poles, the wires hissing and sparking as they fell into the brown flood. The?Boston Globe?reported that people ‘were picked up and hurled many feet’. Rivets popping from the tank scourged the neighbourhood like machine gun bullets, and a small boat was found slammed through a wooden fence like an artillery shell. By the time it passed, the wave had killed 21 people, injured 150, and caused damage worth $100 million in today’s money. All caused by molasses.

While most of us probably think of molasses as a tasty ingredient in treats like gingerbread, the sticky stuff has quite a few other uses. With a little know-how one can turn molasses into rum or industrial alcohol fairly easily, and the Purity Distilling Company had built the gigantic tank in Boston?s North End in 1915 to supply its alcohol-making operations. The steel tank was enormous and capable of holding million gallons of molasses. (Although Prohibition kicked in with Nebraska?s ratification of the Eighteenth Amendment the very next day after the 1919 disaster, the United States Industrial Alcohol Company, Purity Distilling parent company, still had a license to distil alcohol for industrial applications.)

Jan. 20, 1919: A big section of the molasses tank smashed into the walls of the freight house of the Bay State Street Railway Co. with enough force to tear the structure apart. Photo: BOSTON GLOBE ARCHIVE

Jan.16, 1919: The flood knocked down a house and smashed vehicles up and down Commercial Street. Photo: BOSTON GLOBE ARCHIVE

At the time, molasses was a standard sweetener in the United States, used in cooking and in fermentation to make ethanol, which in turn could be made into liquor used as an ingredient in munitions manufacture, an aspect of the business that had been booming during the First World War.

At 529 Commercial Street in North Boston, the 2.3 million gallon Purity Distilling Co. storage tank was filled to capacity with molasses awaiting transfer to the company’s distillery in Cambridge. The weather was mild for January, a relief from the cold snap that had been biting the area for several days. The 50 ft-high tank, which was 90 ft in diameter, dominated the neighbourhood where Commercial Street and the elevated railway tracks made 90-degree turns as they approached the harbour, a congested area densely populated with Italian immigrants and interspersed with pockets of Irish people, who would come to dominate the city. Eighteenth-century American patriot Paul Revere ‘s house and the home of colonial governor Thomas Hutchinson were in the neighbourhood, along with an area of blacksmith shops, a slaughterhouse, modest homes and the trolley company’s freight sheds.

The tank itself was just over three years old. It was constructed of large curved steel plates, seven vertical rows of them overlapping horizontally and held together with rows of rivets, the whole set into a concrete base. Its construction had cost United States Industrial Alcohol (USIA), Purity’s parent company, $30,000. It was perfectly located for USIA, just 200 ft from the harbour and ships that brought molasses from Cuba, and near the railroad tracks that would move the molasses from storage.

Yet the five-storey storage facility was never properly tested – by filling it with water – because a shipload of molasses was due only days after the completion of the tank in December 1915. From the beginning leaks had appeared. Streaks of molasses ran down the sides of the tank, and people living nearby filled up cans for home use. Children would scrape the leaks onto sticks to make molasses suckers. Neighbours and workmen had also reported ominous rumbling noises inside the structure.

With the war over, USIA needed to find other markets than the munitions industry. It found a solution in the looming possibility of Prohibition, which was to ban all sales of alcohol in the United States after a one-year grace period. Hoping to cash in on pre-Prohibition demand, USIA retooled its Cambridge plant for grain alcohol and produced as much as it could. On January 15th, 1919, the tank held 2.3 million gallons of molasses weighing an estimated 26 million pounds, almost one-and-a half times as much weight as the equivalent volume of seawater.

The massive tank was nearly full on January 15 thanks to a recent infusion of 2.3 million gallons of Puerto Rican molasses. Just after noon, something went horribly wrong. Witnesses later recalled hearing a noise like gunfire as the tank?s rivets popped and the steel sides ripped open. Suddenly, 26 million pounds of molasses were tearing down Commercial Street in a huge wave.

Fire House no. 31, damaged in the Molasses Disaster

Section of tank after Molasses Disaster explosion at 1 p.m. on January 15, 1919. Courtesy trustees of the Boston Public Library/Leslie Jones Collection

Firemen standing in thick molasses after the disaster. Muck drips off the ladder’s rungs.

It was around 12.30pm, lunchtime for many workers, when the tank broke. Buildings of the nearby Northend Paving Yard were instantly reduced to kindling as the molasses cascaded out. The three-story Engine 31 Fire House was torn from its foundations, trapping three firefighters who fought to keep their heads above the rising tide. A piece of the tank was blown into the elevated railway tracks, breaking girders and almost forcing a northbound train off its tracks. Seeing a brown mass surging towards him, Royal Albert Leeman, a brakeman for the Boston Elevated, stopped his train and ran up the tracks to stop a second train.

The entire waterfront area was levelled and rails from the overhead railway dangled like Christmas tinsel.

First on the scene were 116 sailors from the lightship USS?Nantucket?that was docked nearby. They were soon joined by Boston police, Red Cross workers and army personnel. When Suffolk County medical examiner George Magrath arrived, several bodies had already been pulled from the molasses. He said they looked ‘as though covered in heavy oil skins … eyes and ears, mouths and noses filled’. A makeshift hospital was set up at Haymarket Relief Station about half a mile from the waterfront, and volunteers removed molasses from victims’ noses and mouths so they could breathe. Those already on duty were soon covered from head to foot with brown syrup and blood,’ the?Boston Post?reported. ‘The whole hospital reeked of molasses. It was on the floors, on the walls, the nurses were covered with it, even in their hair.’ At the destroyed city stables, police shot injured horses trapped in the molasses.

The rescue continued for days. Bodies were often so covered by a brown glaze that they could not be seen. The body of truck driver Flamino Gallerini was taken from the water underneath the railroad freight houses eleven days after the tank burst, and almost four months after that a final body, that of Cesare Nicolo, was pulled from the water under the Commercial Wharf.

Firefighters and others stand in a pool of molasses after the explosion of a molasses storage tank owned by the United States Industrial Alcohol Company in Boston on January 15, 1919. About 2.3 million gallons of molasses flooded the area, killing 21 people, injuring 150, trapping a dozen horses, and destroying buildings, homes and part of the elevated train.

A giant wave of a sticky foodstuff sounds like something from a cartoon, but the surging molasses was a shockingly destructive force. The wave moved at upwards of 35 miles per hour, and the power was sufficient to rip buildings off of their foundations. The molasses snapped the support girders from an elevated train track and smashed multiple houses. The Massachusetts Foundation for the Humanities? website says the property damage alone totaled around $100 million in today?s dollars.

The human cost of the disaster was even grimmer. The wave of molasses moved so quickly and so forcefully that anyone who was unlucky enough to be in its way didn?t stand much of a chance. They were either knocked over and crushed or drowned in the goo. The flood claimed 21 lives, and another 150 people suffered injuries. Any flood would have been disastrous, but the viscous nature of molasses made rescue attempts even trickier. Medics and police officers arrived on the scene quickly but had to slog through waist-deep goo to reach victims.

Even after the victims had been pulled from the muck, cleanup crews quickly learned that getting rid of two million gallons of molasses is no small task.

Fire-fighters couldn?t just use their hoses to blast the molasses off of building and streets with fresh water. Eventually they realized that saltwater would cut the hardened molasses and enable them to hose it down the streets into gutters. Thanks to all the foot traffic of rescue workers, cleanup crews, and rubberneckers, the sticky mess quickly moved around the city via peoples? shoes. In all, the cleanup effort required over 80,000 man-hours.

The rescue continued for days. Bodies were often so covered by a brown glaze that they could not be seen. The body of truck driver Flamino Gallerini was taken from the water underneath the railroad freight houses eleven days after the tank burst, and almost four months after that a final body, that of Cesare Nicolo, was pulled from the water under the Commercial Wharf.

Cleanup crews used salt water from a fireboat to wash the molasses away, and used sand to try to absorb it. The harbour was brown with molasses until summer. The cleanup in the immediate area took “weeks”, with more than 300 people contributing to the effort. The cleanup in the rest of Greater Boston and its suburbs would take an indefinably longer time. Rescue workers, cleanup crews, and sight-seers had tracked molasses through the streets and spread it to subway platforms, to the seats inside trains and streetcars, to pay telephone handsets, into homes, and to countless other places. “Everything a Bostonian touched was sticky.”

The United States Industrial Alcohol Company was quick to blame everyone?s favorite early 20th-century scapegoats: anarchists. The company claimed that since its alcohol was an ingredient in government munitions, anarchists must have sabotaged the tank by detonating a bomb. Another theory explained that the molasses had fermented inside the tank, which led to an explosion.

Investigators soon found the real culprit, though: absurdly shoddy construction work. The company had been in such a hurry to get the tank built back in 1915 that it didn?t cut corners so much as it ignored the corners completely.

The man who oversaw the construction wasn?t an engineer or an architect; in fact, he couldn?t even read a blueprint. The tank needed to be an engineering marvel to hold all that weight, but the company never even consulted an engineer on the project. Basically, it threw up a gigantic tank as quickly and cheaply as possible, skimped on inspections and safety tests, and hoped for the best.

Boston Post, Public Domain, Wikimedia Commons

But for nearly 100 years, the Great Molasses Flood has remained a great mystery. How, on a cold winter day, could a tank full of molasses move so quickly and cause so much damage?

It was the unlikeliest way to drown. The first physics analysis of Boston?s?Great Molasses Flood?shows that cold temperatures and unusual currents conspired to turn slow sticky goop into a deadly speeding wave.

For nearly a century, historians have wondered why such a famously slow-moving fluid wreaked such widespread devastation.

Molasses is what?s known as a?non-Newtonian fluid?of the shear-thinning variety, meaning it flows more easily in response to applied stress.

But when it?s cold, the stuff behaves more like a classic fluid. In particular, the viscosity increases dramatically as the temperature drops, as was found when molasses was tested in a cold room by Nicole Sharp, an aerospace engineer turned?science communicator?who runs a?Tumblr blog on fluid dynamics, and Jordan Kennedy at Harvard University gathered as much data as they could from historical records, including newspaper articles, old city maps and weather reports. They ran experiments on how molasses flows under various conditions, then fed the data into computer models.

?It took several minutes just to pour 48 milliliters into a graduated cylinder,? Sharp says. There?s a reason for the adage ?Slow as molasses in January?.

So, given the cold temperatures in Boston at the time, the extent of the flood was a puzzle. Newspaper headlines speculated that a bomb may have caused the molasses to spread at such a rapid rate.

Fluid dynamics offers a better explanation. The true culprit: gravity currents, which come into play when a dense fluid spreads horizontally into a less dense fluid (in this case, molasses into air). It?s similar to how dense cold air will flow through an open door into a warm room, even if there is no wind to drive it. The density of the molasses alone would account for the speed of its initial spread. ?Basically, you got bowled over by a tidal wave of molasses,? says Sharp, likening the effect to a sticky-sweet tsunami made of a substance 1.5 times as dense and several thousand times more viscous than water.

Temperature also played a critical role in the aftermath of the flood. On the fateful day, the molasses in the tank was slightly warmer than the surrounding air. But once the tank ruptured and the molasses spread, it cooled quickly, making it even more viscous ? and much more dangerous.

The initial onslaught left victims covered in suffocating molasses as rescuers struggled to save them, waist-deep in the goo. Much like quicksand, the more people thrashed about, the more deeply they found themselves trapped in the treacle.

Nicole Sharp:??It seems like that would be the point where it’s not as dangerous any more. It’s not crashing through buildings after that first minute. It’s just kind of oozing instead. But it turns out that, because it was cold?and because the molasses was cooling, that, if anything, that made the molasses more dangerous. Now?people who have been knocked down by that initial wave who may have been pinned in wreckage are trapped in places where they have to try to keep this molasses away from their mouth and nose so they can breathe while people are trying to come and get them. That extra cold makes the molasses easily four or more times as viscous as before and that makes it much harder to fight.?

By Unknown – Anthony Mitchell Sammarco. Boston’s North End. Arcadia Publishing, 2004, Public Domain, Wikimedia Commons

In 2015, a?study shed light?on the cause of the collapse, finding that the tank was stressed well beyond capacity and made from a steel susceptible to fracture ? the same type used on the Titanic.

Ronald Mayville, a senior structural and metallurgical engineer with Simpson, Gumpertz & Heger in Waltham who has researched the disaster for years in his spare time, said several design flaws led to the catastrophic failure. The steel was too thin to withstand the enormous stress of 2.3 million gallons of molasses, a weakness builders should have known at the time.

What builders at the time could not have known was that the type of steel used for the tank was brittle because it contained a low amount of the chemical element manganese, making it more likely to crack. ?The steel conformed to the standards of the time,? he said. ?But now it?s known you need to have a higher ratio.?

Mayville?s findings run counter to one of the main theories behind the collapse ? that a buildup of carbon dioxide inside the tank burst the tank?s rivets.

After a three-year trial, an auditor ruled against the company that owned the tank, US Industrial Alcohol, finding that the tank?s riveted construction did not meet structural standards. But the exact cause of the failure was not determined.

Mayville analyzed the collapse using modern engineering techniques, such as finite element analysis. He found that the fracture probably began in the 20-inch manhole, and that a rivet hole directly above was highly stressed and could have deteriorated.

?Today we know you have to reinforce the side of the hole to keep the stresses down,? he said.

Mayville said the builders were probably under pressure to build the tank quickly and never went back and reinforced certain areas.

The tank had been filled nearly 30 times since its first use in 1916, but was near capacity only four times, Mayville said. The repeated use, and the added weight, probably contributed to the disaster, he said.

Mayville, who has long held an interest in engineering disasters, said his work received a major boost by the discovery of an archive at Lehigh University that belonged to a consultant who testified in the trial.

?That turned out to be a treasure trove?

Local residents brought a class-action lawsuit, one of the first held in Massachusetts, against the United States Industrial Alcohol Company (USIA), which had bought Purity Distilling in 1917. In spite of the company’s attempts to claim that the tank had been blown up by anarchists(because some of the alcohol produced was to be used in making munitions), a court-appointed auditor found USIA responsible after three years of hearings. United States Industrial Alcohol Company ultimately paid out $600,000 in out-of-court settlements. Survivors of the fatal victims reportedly received around $7,000 per victim

United States Industrial Alcohol did not rebuild the tank. The property formerly occupied by the molasses tank and the North End Paving Company became a yard for the Boston Elevated Railway (predecessor to the Massachusetts Bay Transportation Authority). It currently is the site of a city-owned recreational complex, officially named Langone Park, featuring a Little League Baseball field, a playground, and bocce courts. Immediately to the east is the larger Puopolo Park, with additional recreational facilities.

A small plaque at the entrance to Puopolo Park, placed by the Bostonian Society, commemorates the disaster. The plaque, titled “Boston Molasses Flood”, reads:

On January 15, 1919, a molasses tank at 529 Commercial Street exploded under pressure, killing 21 people. A 40-foot wave of molasses buckled the elevated railroad tracks, crushed buildings and inundated the neighborhood. Structural defects in the tank combined with unseasonably warm temperatures contributed to the disaster.

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