21 people were killed on Commercial St in the North End
when the tank of molasses ruptured and exploded. Wiki.
When USIA’s steel tank full of molasses ruptured in 1919, it was a perfect storm. At lunch time in Jan 1919, a giant tank of molasses burst open; 2+ million gallons of thick liquid poured out rapidly, reaching speeds of c35 mph. The day’s mild conditions probably aided the spread of molasses, which flowed outward for 2 blocks. Conditions grew worse that night as temperatures dropped, causing the liquid to become increasingly viscous. Already pinned down by fallen buildings, some victims then became stuck in molasses, 30cm deep in some places. Rescue efforts would have likely been easier if the accident had happened in hot July and the molasses had been able to spread well away from the tank. The molasses flooded streets, crushed buildings and trapped horses in an event that killed 21 people and injured another 150.
Who did it? When the molasses tank burst, the public wondered whether Italian anarchists had blown it up, presumably because some of the alcohol produced was to be used in making munitions. USIA’s subsidiary, The Purity Distilling Co., blamed the explosion on an anarchistic cell who had been sending the company letter bombs. The theory was that anarchists climbed a ladder and dropped pipe bombs into a fermentation vent, causing the tank to explode. The Boston Evening Globe agreed. If it was a terrorist act, the Boston Company would be absolved of any responsibility! It was not impossible, as bombings were common at the time. However there was no evidence.
Even while the company repeated that the tank failed because it was sabotaged by Italian anarchists, a long investigation involving 1,000+ witnesses determined the case properly. The real culprit was shoddy construction in the beginning, and fermentation in the tank later on. Analyses have since pinpointed the factors that combined to create the disastrous event: flawed steel, safety oversights, fluctuating air temperatures and the principles of fluid dynamics. The structural problems of the steel tank were devastating. Designed to hold 2.5 million gallons of liquid, it measured 50’ tall and 90’ in diameter. But its narrow steel walls were too thin to support the weight of a full tank of molasses. Flawed rivet design was another problem and tough stresses on the rivet holes created the first cracks. Although molasses had been poured into the container 29 times, only 4 of those refills approached capacity. The 4th top-off was 2 days before the disaster, when a ship arrived from Puerto Rico carrying 2.3 million gallons of molasses.
Structural engineers already knew better, back in Jan 1919. But the tank had been built quickly in winter 1915 to meet rising demand for industrial alcohol, which could be distilled from molasses and sold to weapons companies to make WW1 dynamite and other explosives. And instead of inspecting the tank and filling it with water first to test it for flaws, USIA ignored all warnings, including visible cracks.
When shards of steel from the tank’s walls were brought into the treasurer’s office as evidence of the potential danger, engineers did not know that the steel had been mixed with too little manganese. That gave it a high transition temperature, making the metal brittle when it cooled below 15c. The air temperature on the day of the disaster was 4c. Its brittleness might have been a final straw.
When it turned out that the tank failed as a result of neglect, the victims and their families sued. The individual lawsuits were combined into one big lawsuit, one of the first class-action lawsuits in Mass. In an age when little government oversight or regulation was normal, the disaster also led to new corporate regulations imposed upon Boston industries. The trial had gathered input from tons of expert witnesses, producing 20,000 pages of conflicting testimony. And after 5 years of hearings, the court-appointed auditor found the USIA Company was responsible. Even though many questions remained, the company did eventually pay out $628,000 in damages to the victims’ families.
The Molasses Tank built and photographed in 1915
before it collapsed and flooded North Boston in 1919
Throughout, USIA’s famous defence lawyer Charles Choate repeated the company story, blaming the disaster on Italian anarchists. Choate's case was designed to prey on Boston’s paranoia over the activities of Italian anarchists on the wharfs. The Bolshevik Revolution in Russia and the end of WW1 had ushered in the Red Scare in modern American history. In Boston, that anxiety focused on the local Italian immigrants, culminating with the appalling treatment of Italian anarchists Nicola Sacco and Bartolomeo Vanzetti the very next year (1920).