A tank by the harbor
In Boston's North End, a distillery stored molasses to turn it into alcohol – some of it for munitions. Its tank was 15 meters tall and 27 meters wide. On 15 January 1919, at around 12:30 p.m., it burst. A wave up to 7.6 meters high swept houses off their foundations. 21 people died and 150 were injured.
Your guess
How fast was the molasses wave, by estimates?
Then it became a trap
After that, viscosity took over. Molasses gets much thicker as it cools: from 10 to 0 degrees, its viscosity triples. The warmer load cooled quickly in the January air. Anyone caught could barely get free; some suffocated. Rescuers only gave up the search after four days.
A tank full of flaws
The tank was poorly built and barely tested. Construction was overseen by a treasurer with no engineering experience; he skipped a proper water test and had the leaking tank painted brown. A 2014 analysis found the steel was only half as thick as it should have been, and too brittle.
The aftermath
119 residents sued together – one of the first class actions in Massachusetts. The parent company claimed anarchists had blown up the tank. After three years of hearings, an auditor still found it responsible; it paid $628,000. Afterwards, Boston required engineers to file their calculations.
