The Sticky Science Behind the Deadly Boston Molasses Disaster

On January 15, 1919, 21 people were killed in the Great Boston Molasses Flood. Over two million gallons of molasses burst out of a defective tank and traveled in a wave estimated to be between 15 and 30 feet tall. That all sounds a little suspicious, especially to people who have actually used molasses in the kitchen. 

Though an anarchist terrorist attack was first blamed for the calamity, investigators soon pointed at the holding tank’s shoddy construction. But the question has remained, why did the molasses explode as a wave and not just slowly drip out of the tank? A group of students at Harvard investigated the event and presented their conclusions at recent meeting of the American Physical Society.
“I’m originally from Arkansas, where we have an old expression: ‘Slow as molasses in January,”​ Nicole Sharp, aerospace engineer and science communicator who led the group, tells William Kole at the Associated Press. “Oddly enough, that’s exactly what we’re dealing with here, except that this molasses wasn’t slow.”

The students studied the history of the molasses flood in detail, and came up with the reasons why molasses flowed like water on that January day. Read what they found at Smithsonian.