BOSTON – A modern-day metallurgical engineer is shedding new light on one of the more bizarre yet most tragic episodes in the history of Boston.

In January 1919, a giant storage tank in the city’s North End ruptured, sending 2.3 million gallons of molasses pouring down city streets, killing 21 people.

Ronald Mayville, a senior structural and metallurgical engineer with Simpson, Gumpertz & Heger in Waltham, has researched the disaster for years in his spare time.

He told The Boston Globe the walls of the tank were at least 50 percent too thin and the type of steel used was brittle because it contained a low amount of the chemical element manganese, making it more likely to crack.

His research was featured in the September edition of Civil and Structural Engineer Magazine.