The Great Molasses Flood of 1919

A headline of the disaster from the Boston Daily Globe

Molasses ain't always sweet. If you doubt me, consider the 21 people who were killed in Boston's Great Molasses Flood of 1919 - a tragedy that sounds as whimsical to the ear as it was deadly in reality. 

On January 15th, 1919 (95 years ago this month) a sticky tsunami surged through the streets of Boston as a 5-story-high, 90-foot-wide metal storage tank, filled with over 2 million gallons of molasses, unexpectedly burst. Moving at 35 mph, the tidal wave stood 25 feet high and swallowed everything in its path as it swept through the city's North End neighborhood. The people and animals who weren't immediately drowned or crushed found themselves subsequently trapped in a chest-deep mire of gelatinous liquid. The wave hit with such force that it leveled entire buildings and moved a stone firehouse off its foundation. 

A dull, muffled roar gave but an instant’s warning before the top of the tank was blown into the air ... Two million gallons of molasses rushed over the streets and converted into a sticky mass the wreckage of several small buildings.
— New York Times contemporary news account of the disaster

The storage tank's failure was jointly caused by its poor construction (it leaked so badly that it was painted brown to hide the defect) and the carbon dioxide produced by the fermenting molasses it held within. A warm spike in temperature that day exacerbated the ongoing chemical reaction and the tank's internal pressure increased to an unsustainable level. Kaboom.

Although the story may sound like something out of a children's tale, the real-life devastation was serious indeed. 

Witnesses said that the sound of the rivets exploding from the tank was similar to the noise of a machine gun and the rumbling caused by the wall of molasses was akin to a train chugging through town. In the aftermath of the disaster, the viscus nature of the mess resulted in 80,000 man hours spent to remove it (Boston Harbor was colored brown through the Summer) and caused over $100 million in damage. For years afterwards, on warm days the locals claimed they could still smell the pungent residue of molasses in the air. 

What was all that molasses doing there to begin with, you ask? Molasses is a key ingredient in the creation of alcohol and the tank in question was fueling the production capability of Purity Distilling, a locally based rum manufacturer. As the 18th Amendment legalizing prohibition was about to pass, a fearful group of decision makers overfilled the tank in the hopes that they might still use the precious molasses to produce alcohol for industrial purposes. The ensuing class action suit against Purity's parent company, the United States Industrial Alcohol Company, resulted in an award of $7,000 to each victim's family.