The Boston Molasses Flood of 1919

Cost-cutting was probably behind design flaws that led to a syrupy wave streaming through the streets of Boston.

Having holidayed recently in Cornwall I can now vouch for two things. First, waves are astonishingly powerful. Secondly, middle-aged historians shouldn't try to surf. On the upside however, the subsequent period of convalescence has given me an excellent opportunity to think about waves in general, and one in particular.

Molasses is the treacly by-product of refining sugar, and a jolly useful one at that. Not only can you cook with it and eat it, but it can be fermented and distilled to make rum and ethyl alcohol, used to remove rust, added to feedstock and even used in mortar. It is not generally used for surfing. However the terrifying power of a molasses wave has once been experienced.

In the winter of 1918 the United States Industrial Alcohol Company began filling its 15m x 27m molasses tank at 529 Commercial Street, Boston, Massachusetts. This vast container, capable of holding 8,700,000 litres, had been built in 1915 to help sate the USA's appetite for industrial alcohol, largely for use in the munitions business that booming thanks to the outbreak of the First World War in Europe. But the owners, in their haste, had made a number of mistakes.

First among these was the appointment of Arthur Jell to oversee the construction. Jell was not an engineer or architect, but the company reasoned that fabricating a big tank was hardly the same thing as building a railway or a skyscraper, so costly experts were not needed. Jell, who was unable to read blueprints, had little idea how to check if the behemoth rising before him would perform as expected and when it was finished he did not even order a simple stress test to check that it would hold up and not leak.

It did, history records, leak. Indeed there were reports of it 'weeping' molasses as soon as it was filled.

In these days of health and safety, we might have such a tank drained and resealed. However, the solution decided upon at the time was to paint the tank brown so no one would notice.

But for all its leakiness, the tank survived for the next four years, creaking and groaning, but providing locals with the occasional bonus of free molasses which they collected from the regular seepage. Then, on 12 January 1919, a molasses tanker from Puerto Rico docked at the wharf and pumped the tank full. All seemed well, until lunchtime on Wednesday 15 January. That day had dawned unusually warm; temperatures had leapt over two days from a chilly -15.5°C to a comparatively balmy +4.4°C and the people of this densely populated neighbourhood were out and about their business. Around 12.40pm witnesses reported a 'muffled roar' followed by what First World War veterans present said sounded like machine-gun fire. This was the rivets shooting out of the rupturing tank. The ground began shaking 'as though a train were passing' and all hell was let loose.

If a flood of molasses doesn't sound all that terrifying it's worth looking at the statistics. In a matter of seconds nearly nine million litres were released onto Commercial Street in a wave that reached 4.5m high and was reportedly travelling at around 56km/h. Over 14,000 tonnes of syrup surged out, exerting a pressure on everything it hit of around 200kPa. Just the sickly-sweet air blast ahead of the wave threw people off their feet, and the wave itself tore the girders off the Boston Elevated Railway and lifted a train from the tracks. People, horses, trucks, carts and whole buildings were lifted onto the wave and tumbled down the street or into the dock.

Twenty-one people died. Another 150 were dragged injured from the viscous mass. It would take a further 87,000 man-hours to clear the streets and houses, and the harbour remained brown with molasses well into the summer. The smell has not, so local legend has it, gone away to this day.

There was, of course, an inquiry. Fortunately was less of a whitewash than that into the comparable London Beer Flood of 17 October 1814 – 1,470,000 litres of beer from the Meux Brewing Company surging down Tottenham Court Road, drowning eight people – which was declared an 'Act of God'.

The United States Industrial Alcohol Company tried valiantly to claim the molasses flood had been caused by anarchists blowing up the tank, but in the end blame was placed on the poor construction and insufficient testing of the container. In the end the company paid $600,000 in out-of-court settlements. The damage to property was estimated at what would today be around £100 million.

The court case never did get to the bottom of exactly what had caused the tank to fail. It was certainly unusually full and some fermentation in the vessel in the rising temperatures over the previous few days may have increased the strain. One scurrilous suggestion is that the company was stocking up on molasses just before the introduction of Prohibition in the hope of making a killing on the rum market. In truth the real reason may be no more complex than the company's failure to hire a qualified engineer. *

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