In Father Nieuwland's 1904 PhD thesis "Some Reactions of Acetylene," he outlines the synthesis of a poisonous gas from acetylene and arsenic trichloride. He does not like the idea of producing such a harmful product from his beloved acetylene. So, he and the rest of the world forgot about this synthesis for a long time.
That is, until 1918. W. Lee Lewis, a captain in the U.S. Army, is hunting for the most poisonous gasses in existence for use in chemical warfare. While stationed at the Catholic University of America, he happens upon Father Nieuwland's discovery. After working on the synthesis for a time, he finally perfects the process to make Lewisite - "the stuff beside which mustard gas becomes a sissy's scent!"
From Wolf, Howard and Ralph. Rubber: A Story of Glory and Greed. New York: Covici, Friede, 1936.