The Great Boston Molasses Flood

(From Flickr)
It was a pleasant and warm winter day in Boston on January 15, 1919.  A mid-winter thaw had raised the temperature forty degrees from a frigid two above zero just two days earlier.   At midday, workers stood out in the street in their shirtsleeves in the warm sunshine. You could indulge in a fantasy that spring was just around the corner, even though in your head you knew it was a delusion.

It was only four months ago that the Boston Red Sox had won the World Series at the end of a season shortened by World War One, the last title they would win until 2004, with 23-year old pitcher Babe Ruth starting and winning two games (and leading the league for the first time in homers with 11).  The Mayor of Boston was Andrew J Peters, a forgotten figure today who served a term in between mayoral stints for the colorful and legendary James Michael Curley, four time mayor, one-term governor and occasional congressman, once being elected to Congress by the voters of Boston despite his federal indictment for mail fraud (he was convicted and spent five months in prison while serving his Congressional term).  Curley's successor in his Congressional District was John F Kennedy.   The governor that year was a better known figure, Calvin Coolidge, who would resign in 1920 to run for Vice-President on a ticket with Warren Harding and then, upon Harding's death in 1923, ascend to the presidency.

In the crowded North End of Boston, a neighborhood heavily populated by Italian immigrants, it was business as usual at Purity Distilling Company on Commercial Street, just across the street from the wharves on Boston Harbor.  Purity was a leading manufacturer of ethanol, a key component in alcohol and, most importantly, munitions, a part of the business that had rapidly grown during World War One.  Molasses was used as a raw material to ferment ethanol.    Purity was a subsidiary of the United States Industrial Alcohol Company, whose Chairman, Charles Edward Adams, would twenty years later become a director of the Federal Reserve Bank of New York and head the iron and steel branch of the US War Production Board during the next world war.

For those of you familiar with Boston you can find the old location of Purity by walking a few hundred feet north from Old North Church, where lanterns were hung on the evening of April 18, 1775 to warn Paul Revere of the route of Thomas Gage's British troops to the Patriot munitions stored in Concord.  You'll come to the Copps Hill Burying Ground (in use since the 17th century) on your right.  From the rise on which the cemetery is located you'll be looking down onto Commercial Street and just across the street and slightly to your left is where Purity was located.
(From Wikipedia; #1 is location of the molasses tank)
It was just after noon that day when a low rumbling was heard, followed by the earth shaking and then the sound of sharp, distinct noises as thousands of rivets gave way culminating in an explosive roar as a 50 foot tall tank, containing 2.3 million gallons of molasses fractured and spilled its contents onto Commercial Street.

A Boston patrolman, Frank McManus, happened to be very close to the site and quickly got to a police call box shouting "There's a wave of molasses coming down Commercial Street."

Fourteen thousand tons of molasses flowed in a wave that reached 25 feet in height, 150 feet in width with a maximum speed of 35 miles per hour.  Within minutes 21 Bostonians were dead, including two 10-year olds, Maria DiStasio and Pasquale Iantosca, and 150 injured.  Although the North End contained many Italians at least 12 of the 21 dead were Irish (based on THC's look at the surnames) who were laborers employed in the area.

A quick response by cadets from the Massachusetts Maritime Academy along with the firemen and police who soon arrived at the scene saved many lives by pulling people out of the mess where they were in danger of drowning.

(From Flickr) The physical destruction was staggering.  Buildings collapsed or were torn off their foundations, railroad freight cars had been pushed down the tracks and in one case, lifted off the tracks and thrown through a warehouse wall, while the structural beams supported the elevated trainline running down Commercial Street had been damaged.

The Boston Post described the scene (from Mass Moments):

The sight that greeted the first of the rescuers on the scene is almost indescribable in words. Molasses, waist deep, covered the street and swirled and bubbled about the wreckage. 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.

(From Flicker; firemen standing in molasses)  In an article in the August 10, 2013 edition of Scientific American, Ferris Jabr explained ("The Science of the Great Molasses Flood") why the flowing molasses was so destructive:

A wave of molasses does not behave like a wave of water. Molasses is a non-Newtonian fluid, which means that its viscosity depends on the forces applied to it, as measured by shear rate. Consider non-Newtonian fluids such as toothpaste, ketchup and whipped cream. In a stationary bottle, these fluids are thick and goopy and do not shift much if you tilt the container this way and that. When you squeeze or smack the bottle, however, applying stress and increasing the shear rate, the fluids suddenly flow. Because of this physical property, a wave of molasses is even more devastating than a typical tsunami. In 1919 the dense wall of syrup surging from its collapsed tank initially moved fast enough to sweep people up and demolish buildings, only to settle into a more gelatinous state that kept people trapped.

Physics also explains why swimming in molasses is near impossible. One can predict how easily an object or organism will move through a particular medium by calculating the relevant Reynolds number, which in this case 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 more likely everything will go along swimmingly.

Depending on the way it is made, molasses is between 5,000 to 10,000 times more viscous than water. 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. To make matters worse, a man immersed in molasses will not get anywhere with the kinds of symmetric swimming strokes that would propel him in water. Each repetitive stroke would only undo what was done before. Pulling his arm towards himself would move molasses away from his head, but reaching up to repeat the stroke would push the molasses back where it was before. He would stay in place, like a gnat trapped in tree sap. Even burly men struggled to tread molasses in the wake of the Boston Molasses Disaster; horses flailed and brayed, straining to keep their heads aloft and snorting to clear their airways.

What caused the disaster?  Over 100 lawsuits were filed against Purity and United State Industrial Alcohol Company and the Massachusetts Courts appointed Colonel Hugh W Ogden, former Divisional Judge Advocate of the 42nd Infantry Division and co-author of Proceedings and Report of Special War Department Board on Courts-Martial and Their Procedure, to oversee the consolidated cases.  The proceedings lasted until 1925 hearing testimony from more than 1,000 witnesses. The defendants claimed that the cause was a dynamite bomb planted by anarchists. Ogden disagreed, finding that the defendants had demonstrated gross negligence in the construction and operation of the tank.  Poor construction techniques had been used and basic integrity testing neglected before the tank was put into service several years before.  When the tank was initially filled molasses had leaked and the company responded by painting the tank brown to make it more difficult to see the leaks.  Prior to its failure the tank had only been completely filled eight times (the last being at the time of its collapse) and the court found that the immediate cause of the catastrophe was pressure buildup accelerated by the rapid temperature rise combined with the deteriorating condition of the tank over time.

The defendants paid out settlements reported to be approximately $1 million to the various plaintiffs, a very large sum for the times.

Via Travelchannel.com you can see some more pictures and explanations of the disaster:

Sources for this post in addition to the ones cited above:

Eric Postpischil's Molasses Disaster Page
Dark Tide: The Great Boston Molasses Flood of 1919 by Stephen Puleo
The Puleo book is the only full length account of the disaster and is frequently used as a source by the other sources cited here.