On January 15, 1919, a 50-foot tall tank ruptured, sending …

At midday on Jan 15, 1919, the #NorthEnd was full of workers and residents venturing outdoors to enjoy unseasonably warm weather. At about 1 p.m., they heard a low rumble. Many assumed it was a Boston Elevated train. But, within minutes, they realized something was very wrong.

A 50-foot tall tank full of industrial grade molasses had ruptured, sending a 2.3 million gallon wave of molasses rushing through the crowded #NorthEnd.

The hulking molasses tank had been built by Purity Distilling Company only a few years earlier, in 1915. The tank measured 50-feet tall, and rose over the Boston Elevated Railroad tracks that ran next next to it

Tankers delivered shipments of molasses to Copps Hill Wharf, where it was pumped into the tank and stored until it could be sent to distilleries on train cars, like this one.

Though the tank had only been built a few years earlier, locals knew it leaked. Stephen Puleo writes that children collected pails of the molasses. When residents complained that they could see the molasses seeping out at the tank's seams, Purity Distilling painted the tank brown

Structural engineers later reported that the tank's walls were too thin to hold heavy molasses and that the chemical composition of the tank's walls made them vulnerable to cracking.

On Jan15, a combination of the tank's shoddy construction, a sudden temperature change, and a large new shipment of molasses resulted in a rupture of the tank's walls.

The wave of molasses rushed through the #NorthEnd at about 35 mph. It partially knocked an Elevated train off of its tracks, crushed buildings, moved a firehouse and other buildings off their foundations, and suffocated both humans and animals.

The crumpled pieces of the tank littering the debris field showed the force of the molasses wave.

Rescuers, including the Boston Police Department, cadets from the USS Nantucket, docked nearby, and the Red Cross, rushed to the scene. Despite heroic efforts, the molasses killed 21 people and injured 150.

Most of the deceased were laborers and drivers. They also included Pasquale Iantosca and Maria Distasio, two 10-year-olds who had been outside playing and George Layhe, a Engine 31 fireman who had reportedly just finished a game of cards before the molasses hit his firehouse

Cleaning up the molasses and debris was difficult. Molasses coated everything making it almost impossible to move wreckage. City workers finally realized that saltwater broke down the molasses and began spraying the area with water pumped in from the harbor.

Though locals had observed the structural issues with the molasses tank, the tank's owners initially blamed an anarchist plot to bomb the tank. An initial inquiry and a later class-action lawsuit revealed the structural instability of the tank.

In 1925, a court-appointed auditor ruled that the negligence by the tank's owners was to blame for the tank's collapse . The tragedy of Boston's molasses flood led to great changes in the way the United States regulated industries.

According to Stephen Puleo, regulations stipulating that engineers needed to sign and seal plans, building inspectors needed to examine projects, and that architects needed to show their work all came as a result of Boston's molasses flood.

Interested in learning more about the Boston molasses flood? Take a look at our collection of photos documenting the flood: https://t.co/8XjfhMr1nD

For further reading, we recommend Stephen Puleo's book, "Dark Tide: The Great Molasses Flood of 1919." https://t.co/xRnAh2JR0V

For a shorter read, we enjoyed this article from @BostonDotCom : https://t.co/85cvo14d88

And this article from @washingtonpost https://t.co/bZk46bWSwT