One hundred years ago today a dark, viscous wave swamped a neighbourhood in Boston, killing 21, injuring many more, and wreaking a sickly-sweet havoc across a large part of the city. There’s little doubt that the 50 foot tall storage tank that held the 2.3 million gallons of molasses that day in Boston, USA, was poorly constructed. It was built in 1915, with steel sides set into a concrete base and stitched together with rivets. The Purity Distilling Company – which owned the tank – skipped testing it before it was put into service. Arthur P. Jell, who oversaw the construction, didn’t bother to fill the tank with water to check for leaks. Pell had no engineering education or experience, was not an architect, could not read a blueprint, and did not involve engineers in the construction process at any point. The City of Boston did not oversee the tank’s construction, never inspected it, and never required proof that the tank could hold its contents or withstand the pressure of that much molasses. The steel used in the tank was only half as thick as it should have been, and there was insufficient strengthening manganese in the metal.
On the other hand the steel used was considered strong enough for more serious items – it was the same steel, for instance, that was used for the hull of the ill-fated HMS Titanic, which sank in 1912 after colliding with an iceberg. When filled with molasses the tank leaked so badly that it was painted brown to hide the leaks, and locals lined up to collect the leaking molasses. Purity Distilling was a subsidiary of the United States Industrial Alcohol Company and specialised in distilling ethanol. Molasses is also fermented to produce rum.
One reason the storage tank was unusually full to the brim – more molasses was shipped into it by boat from Puerto Rico a few days earlier – was that the very next day, 16 January 1919, the Eighteenth Amendment to the US Constitution was ratified (after almost two years of bitter struggle in Congress), and “intoxicating liquors” were banned in the US, in an act which was to come into force a year later, by January 1920. Purity Distilling was determined to make hay – or rather booze – while the sun shone.
Bodies were still being found several days later but they were difficult to identify, first smashed and then coated, like a human toffee-apple, in a crisp thick brown glaze
The North End neighbourhood was crowded with tenements and filled with immigrant families, many from small Italian towns. As the 14,000 tonne sticky wave ploughed through the streets at 35 miles per hour, it cooled and thickened, trapping men, women, and children in its viscous embrace. Bodies were still being found several days later: they were difficult to identify, having been at first smashed and then coated, like a human toffee-apple, in a crisp thick brown glaze. The explosive power of the sugar-fermenting tank must have been considerable; a 6 ton chunk of Titanic steel flew about 200 feet away.
You may ask, ‘but couldn’t they swim their way out of this sticky disaster?’ The answer is no. Molasses is a non-Newtonian fluid, which means that its viscosity depends on the forces applied to it. Molasses is between 5,000 and 10,000 times more viscous than water. Non-Newtonian fluids such as toothpaste do not shift much if its container is tilted. But when squeezed, it can suddenly splurge out. Because of this physical nature, the 1919 wave of molasses initially moved fast enough to sweep people aside and demolish buildings.
It is impossible for a human to swim in molasses, thanks to a bit of physics known as the Reynolds number, which takes into account the viscosity and density of the fluid as well as the velocity and size of the object or organism. The higher the Reynolds number, the easier it is to swim. The Reynolds number for an adult man in water is around one million; the Reynolds number for the same man in molasses is about 130. A human in molasses will not get anywhere by swimming; each stroke will only undo the previous one. The molasses’ swimmer would fight hard to free himself but, like a wasp in the jam, the more he tried the more he would be stuck. Not a death one would wish for. A Boston Post reporter wrote: “Here and there struggled a form – whether it was animal or human being was impossible to tell. Only an upheaval, a thrashing about in the sticky mass, showed where any life was…Horses died like so many flies on sticky fly paper. The more they struggled, the deeper in the mess they were ensnared. Human beings – men and women – suffered likewise.”
A human in molasses will not get anywhere by swimming; each stroke will only undo the previous one
Damon Hall, a lawyer for the plaintiffs, was ecstatic about the victory, but dissatisfied with Ogden’s damage awards. He said he would now seek a jury trial to determine damages – a threat that United States Industrial Alcohol realised could lose them a very substantial sum, given the general publica antagonism towards big business and big alcohol business especially. Their lawyers immediately offered to negotiate. The two sides quickly reached an agreement, which saw the company making damage payments more than double those recommended by Hugh Ogden. And building regulations nationally were drastically tightened and improved.
The repercussions were still being felt, decades later. More than 500 men slaved 24/7, and they took a week to clean up the worst of the mess. But the scent of molasses lingered across the city and – particularly during hot weather – molasses seeped from buildings for years to come. For months, everything a Bostonian touched felt sticky. The Great Boston Molasses Flood of 1919 was not the origin of the saying “come to a sticky end” (that derives from the practice of packing bodies of the dead in honey, in order to preserve them during a long voyage home) – but it certainly exemplifies it.