On January 15th, 1919, in what was probably the most bizarre disaster in United States' history, a storage tank burst on Boston's waterfront releasing two million gallons of molasses in a 15 ft-high, 160 ft-wide wave that raced through the city's north end at 35mph destroying everything it touched.

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.

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 a liquor used as an ingrethent 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.

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 threestorey 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.

The clean-up eventually took some 87,000 man hours. Fire department pumps groaned as they removed thousands of gallons of molasses from cellars. Workers used chisels, brooms and saws to break up the hardening gunk. The harbour water, used to flush the streets clean, was brown until the summer. Meanwhile, rescue workers, sightseers and residents carried the gooey brown residue on their clothes and boots to other parts of the city, making streetcar seats, trolley platforms and public phones sticky. The whole city smelled of molasses.

In February, a month after the disaster, the Chief Judge of Boston Municipal Court, Wilfred Bolster, made public the results of his investigation into the tragedy and blamed the tank itself, saying evidence indicated it was 'wholly insufficient in point of structural strength to handle its load'. He also held USIA to be guilty of manslaughter. District Attorney Joseph Pellatier then presented evidence to a grand jury, which decided the tank had been built without a sufficient inspection of its plans and construction by the city. But the jury stopped short of charging the company with manslaughter.

Also in February 1919, a professor at the Massachusetts Institute of Technology, CM. Stoffard, examined pieces of the shattered tank and stated that its shell had been too thin and was held together with too few rivets.

By August 1920, 119 separate lawsuits had been filed against USIA. At a preliminary hearing, the company's lawyers and various plaintiffs crammed into Boston's courthouse. In response to the complexity of the case and the number of lawyers and plaintiffs involved, Superior Court Judge Loranus Eaton Hitchcock consolidated the suits with one lead attorney for each side and appointed an 'auditor' to hear evidence and issue a report as to liability and damages. The cases could then move on to actual jury trials, he said, but it was hoped the auditor's conclusions would streamline that process.

Hugh W. Ogden, a Boston attorney who had reached the rank of colonel during the First World War, was appointed auditor. He had served as judge advocate of the 42nd Infantry Division, and had been awarded the Distinguished Service Medal. After the war he had served with the Army of Occupation in Germany as a legal adviser.

During the hearing before Ogden, which began on August 9th, 1920, USIA maintained the failure of the tank had been due to sabotage, probably by Italian anarchists, who were known to be active in the country and in Boston at the time. They claimed a telephone threat against the tank had even been received a year earlier, leaflets threatening violence had been found posted in the neighbourhood only days before the disaster, and a bomb had been discovered at another USIA facility in 1916.

The plaintiffs argued that the tank was the problem. They showed the material used to build it was thinner than that specified and that the man in charge of construction, Arthur P. Jell, had spent his career as a financial officer. He could not read the plans and had sought no engineering advice. The plaintiffs also showed the tank's construction had been rushed and it had not been properly tested.

By the time the hearing was over three years later, Ogden had listened to 921 witnesses. The transcript ran to almost 25,000 pages and lawyers had presented 1,584 exhibits. Ogden was to study the material for another year before issuing his conclusions. It was the longest and most expensive civil suit in Massachusetts's history.

Ogden gave his 51-page verdict on April 28th, 1925 and held the company liable for the disaster. He ruled that USIA's attorneys had given no evidence to support their theory about anarchists. Yet evidence had been supplied of the inferior material and construction of the tank. Ogden wrote: 'The general impression of the erection and maintenance of the tank is that of an urgent job ... I believe and find that the high primary stresses, the low factor of safety, and the secondary stresses, in combination, were responsible for the failure of the tank.'

Ogden recommended around $300,000 in damages, equivalent to around $30 million today, with about $6,000 going to the families of those killed, $25,000 to the City of Boston, and $42,000 to the Boston Elevated Railway Company. Faced with the negative ruling, lawyers for USIA quickly agreed an out-of-court settlement with slightly higher awards for the families of those killed and injured.

As a result of the tragedy, Boston city authorities began requiring that plans for all construction projects be signed off by an engineer or architect and filed with the city's building department, a practice that soon spread throughout America.

The tank was never rebuilt. The site where it stood is now a public park with bocce (Italian boules) courts and Little League baseball fields, slides and swings. All that remains of that terrible day 90 years ago is a small plaque at the entrance of the recreational complex. Yet local residents insist a faint smell lingers to this day. They say that on warm summer days the air is still tinged with the sweet, cloying scent of molasses.

Chuck Lyons is a retired newspaper editor and freelance writer. He lives in Rochester, New York.