What Caused the Boston Molasses Flood of 1919?

Posted on 28 Oct 2015 15:44

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As bad as an ordinary flood can be, can you imagine if instead of water, the flood was composed of thousands of gallons of molasses?

Just such a flood occurred in Boston, Massachusetts on January 15, 1919, when a storage tank filled with two million gallons of molasses catastrophically breached.

It is surely one of the most bizarre disasters in American history.

The Failure of the Molasses Tank

This was not just a simple failure, it was a violent breach, often described as an explosion.

Metal and other debris from the tank was thrown outward, some of which cut through the girders of the elevated railway.

The molasses poured outward through the streets, causing a wall of molasses up to 15 to 30 feet high and moving at a speed of 35 miles and hour.

Twenty-one people died from the molasses flood, and 150 were injured either from being swept up in the flood or buried in the debris of collapsing structures. Many horses, cats, and dogs were also killed.

Great Boston flood disaster elevated railway collapse

Elevated railway collapsed from flying tank debris after the great molasses flood.

You'd think molasses would flow very slowly, but survivors said that you couldn't get away from onrushing, viscous, rumbling juggernaut. It even knocked buildings right off their foundations and crumpled rail-cars in the freight yard. Among many newspaper reports, one in the Post described the event:

A rumble, a hiss—some say a boom and a swish—and the wave of molasses swept out. It smote the huge steel girders of the "L" structure and bent, twisted, and snapped them, as if by the smash of a giant's fist. Across the street, down the street [Commercial Street], it rolled like a two-sided breaker at the seashore. Thirty feet high, it smashed against the tenements on the edge of Copp's Hill. Swirling back it sucked a modest frame dwelling (the Clougherty house) from where it nested beside the three-story brick tenements and threw it, a mass of wreckage, under the "L" structure.

Then, balked by the staunch brick walls of the houses at the foot of the hill, the death-dealing mass swept back towards the water. Like eggshells it crushed the buildings of the North End yard of the city's paving division…To the north it swirled and wiped out practically all of Boston's only electric freight terminal. Bil steel trolley freight cars were crushed as if eggshells, and their piled-up cargo of boxes and merchandise minced like so much sandwich meat.

In the resulting wreckage, molasses coagulated into a sticky mess which lingered for months. Residents say that on some days you can still smell it!

As you can imagine, nobody had ever thought of how you would clean up after a huge molasses flood. At first, the city tried to wash it away using the fire hydrants, but this did no good. The city eventually pumped salt water from Boston harbor into the town, which, if it didn't exactly wash it away, thinned it enough to let it flow into the harbor. The molasses had to be pumped out of the basements of buildings. Then, of course, there was the wreckage.

Wreckage and destruction after Great Boston Molasses Flood

The Aftermath of the Great Boston Molasses flood, Courtesy of Boston Public Library

Why So Much Molasses?

The molasses filled tank was owned by Purity Distilling Company, and sat on Commercial Street near Boston harbor, in Boston's North End. Fifty feet tall and 280 feet around, it was the biggest "building" in the neighborhood.

The tank held shipments of Caribbean molasses that would be distilled into rum or alcohol for industrial use. By January 17, 1920 prohibition was in effect. However, during this time, industrial alcohol was in high demand because of World War I, since alcohol was used for the manufacture of munitions. Therefore, the tank was always full. For three years, the people of the neighborhood watched in trepidation as the tank was refilled with millions of gallons of molasses, groaning and shuddering as the weight increased up to 13,000 tons.

The tank was never water-tight, or in this case, molasses-tight. The black stuff seeped out through cracks and ran down the sides of the tank.

And then, on January 15, 1919, it failed, horribly.

Firemen standing and working in molasses after the great Boston molasses flood

Firemen Standing in Deep Molasses After the Flood

The Cause of the Great Molasses Flood

There was rampant speculation about the cause. The civil preceding that followed had 119 claimants and lasted 3 years, making it the longest civil trial in Massachusetts history. Both in the trial, and in the press, debate about the cause of the disaster was rampant.

By this time, the Purity Distilling had been bought by the United States Industrial Alcohol company (USIA). The attorney for USIA, Henry F.R. Dolan, insisted that it was beyond question that "evilly disposed persons" were responsible for destroying the tank, and that the tank was structurally sound. Basically, according to USIA, the tank had been destroyed by enemy communists. Since the USIA was a major military supplier (of alcohol), and according to the company, had already received threats from anarchists, they were an obvious target.

It was the opinion of U.S. inspector Daniel T. O'Connel, that the tank had collapsed because it was structurally weak. This, of course, was the opinion of the plaintiffs in the trial as well, and they argued that company treasurer Arthur P. Jell, the tank's construction overseer, had failed to submit any plans for the thank to an architect or engineer so that it could the design could be reviewed. During the tank's construction, and once it was built, it was argued, Jell had failed to perform any standard safety tests, ignoring repeated warnings that the tank may not be sound.

USIA was not able to make much of their saboteur theory, and the court ruled in favor of the plaintiffs, resulting in a $600,000 settlement, saying "the absence of every kind of skilled technical supervision and inspection by the defendant" was the cause of the disaster.

section of ruined molasses tank after the great molasses flood

These men are standing near a huge section from the destroyed molasses tank.

Surely though, structurally unsound tanks don't explode so catastrophically and send debris flying in all directions? Well, it is not clear how "explosive" this failure really was but the tank certainly did not go out with a whimper. It may well have failed some day, but as O'Connel believed, it is thought that the tank's weakness conspired with a very warm day to produce the explosion. The warmth caused an unusually high amount of fermentation in the molasses. This fermentation caused a buildup of pressure in the tank which pushed against the sides of the tank and finally split the tank apart.

Residents who were there said that just after 12:30, they heard a deep rumbling noise followed by a series of rapid metallic popping noises much like machine-gun fire. This would have been the rivets popping. Then, the tank split apart and the 13,000 tons of molasses wrought its destruction.

If you would like to read a more thorough history of the events of the great Boston Molasses flood, see Dark Tide: The Great Boston Molasses Flood of 1919, by Stephen Puleo.

More Photos From the Great Boston Molasses Flood

The images on this page are made possible by the archival work of the Boston Public Library. You can view more photos of the aftermath of the disaster by visiting the library's dedicated molasses flood Flickr page.

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