NFPA Journal - May/June 2017 - 160

Looking Back

FIRE INCIDENTS AND
OTHER NOTABLE EVENTS
FROM SAFETY HISTORY

WILL

The scene in Boston's North End following the
molasses flood of 1919, which killed 21 people.

NEW RESEARCH HELPS EXPLAIN THE
DEADLY BOSTON MOLASSES FLOOD OF 1919
By Angelo Verzoni
he Great Boston Molasses Flood, which
occurred on January 15, 1919, was triggered
when a large molasses storage tank, housed
just a few feet from one of Boston's busiest
streets, burst open and sent a wave of the
sticky substance through the neighborhood. An estimated
2.3 million gallons of molasses-enough to fill three Olympic-sized swimming pools-gushed from the tank, forming a
wall that was initially 25 feet high and 160 feet wide. Twenty-one people, including a firefighter, were killed, and 150
people were injured.
Nearly 100 years after the disaster, a team of researchers
from Harvard University believes it knows why the peculiar
incident was so deadly: frigid winter temperatures rapidly
cooled the molasses as it exited the tank, making it thicker. The
phenomenon not only prevented people from escaping it, but
also hindered efforts to rescue those who were trapped in it,
according to the researchers. Shmuel M. Rubinstein, a Harvard
engineering professor whose students assisted in the research,

THE NFPA LIBRARY AND ARCHIVE holds a rich collection of books, reports, and photographs that document important moments in fire history. To provide better electronic access for researchers and to preserve our unique archival holdings, work has begun to digitize the files of the Fire Record Department, the original NFPA department
responsible for collecting and analyzing information and compiling statistics about key fires and other events. The incidents featured in "Looking Back" are drawn from this
collection and will eventually be part of NFPA's online archive. For information, visit nfpa.org/library.

160 | NFPA JOURNAL * M A Y / J U N E 2 0 1 7

GETT Y IMAGES

COLD MOLASSES

told The New York Times that he believes fewer people would
have died if the tank had burst in warmer weather.
Researchers studied hundreds of historical documents and
evaluated the flow of molasses at different temperatures. They
presented their findings in November at a meeting of the
American Physical Society's Division of Fluid Dynamics.
Newspaper accounts of the molasses flood describe the
bizarre scene. "Two million gallons of molasses rushed over
the streets and converted into a sticky mass the wreckage of
several small buildings which had been smashed by the force
of the explosion," The New York Times wrote on the day of the
incident. "Wagons, carts, and motor trucks were overturned.
A number of horses were killed. The street was strewn with
debris intermixed with molasses and all traffic was stopped."
The tank was owned by Purity Distilling Co., a subsidiary
of U.S. Industrial Alcohol, which used the alcohol distilled
from the molasses for weapons manufacturing. According to
historian and author Stephen Puleo, the tank burst because
of shoddy construction, coupled with the fact that fermentation triggered by mixing hot and cold molasses was occurring
inside the tank, forming gas and increasing pressure.
A three-year court case led to the adoption of engineering certification laws and stricter rules about engineers and
architects filing building plans with cities nationwide. In his
book about the incident, Dark Tide, Puleo noted that "the
Boston molasses flood did for building construction regulations nationwide what a subsequent Boston disaster, the great
Cocoanut Grove nightclub fire, did for fire code laws."

http://www.nfpa.org/library

Table of Contents for the Digital Edition of NFPA Journal - May/June 2017