In 1919, a wave of molasses swept through Boston at about 35 mph.
On a mild January day, a giant tank holding 2.3 million gallons of molasses burst in Boston's North End. A syrup wave up to 25 feet high tore through the streets, flattening buildings and tipping a streetcar. Twenty-one people died. Residents said the area smelled sweet on hot days for decades.
The tank belonged to the Purity Distilling Company, which stored molasses at the harbour before piping it to a plant that turned it into ethanol, used for drinks and munitions. It stood 50 feet tall and 90 feet across. On 15 January 1919 the temperature had jumped from well below freezing to about 41°F, and a fresh, warmed shipment had recently been added. Around 12:30 pm the tank split open. Witnesses heard a roar and a sound like machine-gun fire as the rivets popped.
Molasses is about 40 per cent denser than water, so the collapse released enormous energy. The wave moved fast enough to sweep people and horses off their feet and hurl a truck into the harbour. Then, as it cooled in the winter air, it thickened, trapping those caught in it and making rescue desperately hard. About 150 people were injured. Cadets from a nearby training ship were first on the scene, wading into the flood; the search for victims lasted four days. In 2016 a Harvard team using old newspapers, maps and weather data, plus a scale model flooded with cold corn syrup, concluded that the reported speed was credible.
Why did the tank fail? It may have leaked from the day it was first filled in 1915. An inquiry found it had been poorly built and never properly tested; the official overseeing construction had no engineering experience and ignored groaning sounds whenever it was filled. Pressure from fermentation and the sudden warmth may have helped. The owner, United States Industrial Alcohol, blamed anarchists.
A court-appointed auditor disagreed. After three years of hearings he found the company responsible, and it paid about $628,000 in damages. The case was one of Massachusetts's first class actions, and the disaster led to new rules requiring licensed architects and engineers to sign off on construction. A sticky footnote in history, it helped shape modern building regulation.
Source: Wikipedia — Great Molasses Flood · Text summarised from Wikipedia (CC BY-SA 4.0)
