The cover of the Boston Daily Globe, January 16, 1919, detailing the disaster. How slow is molasses in January?  Not as slow as you might think.  On January 15, 1919, it was estimated to have moved about 35 miles per hour.  That was the day a large tank containing molasses, 50 feet tall and 90 feet around, burst in Boston’s North End, spilling molasses across Commercial Street and beyond. January 15 was an unusually warm day, hitting about 40º F, following a cold snap.  The rapid warming likely built up pressure that compromised the integrity of the tank.  Rivets popped out of the side of the tank at the Purity Distilling Company as the wall began to collapse, unleashing over 2 million gallons of molasses.  A wave of molasses 25 feet high rushed out, knocking small buildings off their foundations, damaging the girders of the overhead railroad, and flooding several blocks with anywhere from two to three feet.  21 people were drowned in the molasses...