When I think of molasses, I think of the brown, thick, sticky, syrupy stuff my mother stored in her refrigerator. My father would wait, for what seemed like forever, for it to slowly pour out of the jar onto whatever it was he was eating. Who knew that, exactly 100 years ago, the same substance formed a 15-foot high wall and destroyed a neighborhood in the North End of Boston, Massachusetts?
In the early twentieth century, fermented molasses was commonly used to produce industrial alcohol for use in the manufacturing of munitions and other weaponry. In 1915, the Purity Distilling Company, trying to capitalize on the rising sale of industrial alcohol due to World War I, constructed a huge, 50-foot high, 90-foot diameter steel holding tank (capacity of 2.5 million gallons) in the North End of Boston. They planned to use the tank to store shipments of molasses received from the Caribbean before being processed. However, in their haste, the tank was constructed haphazardly.
January 15, 1919 was an unusually warm day in Boston, heating up to over 40 degrees F by mid-day – and it was then that the molasses tank exploded. The tank, recently filled, unleashed a 15-foot high wave of molasses that traveled through the neighborhood at 35 miles per hour. Buildings were destroyed or totally picked up and moved from their foundations. A support girder from an elevated train track was snapped in half. Twenty-one people, unable to flee from the oncoming rush, were drowned, or otherwise fatally hurt, because of the flood; 150 people were injured.
Rescue and cleanup operations after the flood were extremely difficult. First responders struggled through the viscous molasses to help the victims – and the situation worsened as the molasses hardened quickly in the winter air. After the victims were recovered, the cleanup of more than 2 million gallons of molasses was a daunting task. And this task was aggravated by the rescuers and clean-up crews who, after leaving the scene, tracked molasses onto train platforms and seats, payphone handsets and elsewhere around the city as they made their way home. All in all, an estimated 80,000 man hours were spent cleaning up the molasses. For several weeks after the clean-up was completed, the smell of molasses was still in the air. The waters of Boston Harbor were stained brown until summer.
Initially, the company blamed anarchists for blowing up the tank to prevent munition manufacture. Then it was suggested that the warmer than average ambient temperature caused fermentation of the molasses, thus producing carbon dioxide and increasing the internal pressure in the tank which led to the explosion. Although this latter explanation may have contributed to the failure of the tank, it was not the cause; the cause was determined to be the poor design and construction of the tank. Investigators determined that the company constructed the tank without proper design, inspections or safety tests, and that the man they hired to oversee the project was not an engineer nor could he even read a blueprint. They discovered that the tank leaked since its installation and that the company’s solution was to paint the tank brown so that the leaks would be less noticeable. Hence, the company was to blame.
This tragedy helped Massachusetts, and many other states, to develop and enact laws requiring the inspection and approval of plans prior to the beginning of major construction projects.
It is interesting to note a couple of recent studies about the Great Molasses Flood and their findings. In 2014, Ronald Mayville, a senior structural and metallurgical engineer with Simpson, Gumpertz & Heger in Waltham, MA, determined that the steel walls used to construct the tank were half the thickness they should have been in order to withstand the enormous stress applied by 2.5 million gallons of molasses. He also stated that, although manufactured to the standards of the time, the type of steel used did not contain enough manganese which made it brittle. In 2016, Harvard professor Shmuel Rubinstein and some of his Fluid Dynamics students determined that one of the reasons the spill was so deadly was because it occurred during the winter. They discovered that the molasses had just been delivered two days prior to the collapse and that, following what was common practice during that time, the cargo was heated a few degrees to make it less viscous and easier to unload. Therefore, the molasses in the tank was warmer than the surrounding air allowing for the size and quick movement of the wave when the tank initially burst. The cold winter air, however, cooled the molasses quickly, raising the viscosity, and turning it into a deadly weapon. If the tank had burst in the summer, the molasses would have traveled further but been thinner, due to the higher temperature and lower viscosity, and although it would still have created a mess, it probably would not have caused as much death or damage.
Reference:
http://mentalfloss.com/article/27366/bostons-great-molasses-flood-1919
Harvard Study:
https://www.nytimes.com/2016/11/26/science/boston-molasses-flood-science.html?
Structural study:
https://www.bostonglobe.com/metro/2015/01/14/nearly-century-later-new-insight-into-cause-great-molasses-flood/CNqLYc0T58kNo3MxP872iM/story.html
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