On January 15, 1919, the city of Boston suffered a tragedy when a large tank of molasses burst, triggering a major flood of syrup through the city streets.
The incident, known as the Boston Molasses Disaster, the Great Molasses Flood, and the Great Boston Molasses Tragedy, killed 21 people and injured over 150 others. At 12:30 in the afternoon, a tank at the Purity Distilling Company near Keany Square, measuring 50 feet tall, 90 feet in diameter, and containing 2.3 million gallons of molasses burst, sending its contents flooding into the city streets.
Witnesses reported that as the tank collapsed, it sounded like a machine gun as the tank’s rivets shot out and that the ground shook as if a train were passing by.
The wave of destruction was 25 feet high, moving at 35 miles per hour. The force of the wave was sufficient to tip a road road car off the tracks, push buildings off their foundations, and crush the structures. Several blocks were flooded to a depth of 2-3 feet.
The Boston Post reported:
Molasses, waist deep, covered the street and swirled and bubbled about the wreckage … Here and there struggled a form—whether it was animal or human being was impossible to tell. Only an upheaval, a thrashing about in the sticky mass, showed where any life was … Horses died like so many flies on sticky fly-paper. The more they struggled, the deeper in the mess they were ensnared. Human beings—men and women—suffered likewise.
Later investigation determined the tank was constructed poorly and tested insufficiently. Unseasonably high temperatures and rapid change in temperature (the temperature that day rose from a low of 2 degrees F to 41 degrees F), caused fermentation of the syrup and production of carbon dioxide at a rapid rate, increasing the internal pressure. Applying modern engineering analysis, an investigation in 2014 determined the steel was half as thick as it should have been and lacked manganese in composition, contributing to the brittleness of the metal.
An inquiry after the disaster revealed that Arthur Jell, who oversaw the construction, neglected basic safety tests, such as filling the tank with water to check for leaks. When filled with molasses, the tank leaked so badly that it was painted brown to hide the leaks. Local residents collected leaked molasses for their homes.
Today, nearly 100 years after the disaster, some residents insist they can still occasionally smell molasses in that area.