Ira Remsen (February 10, 1846 - March 4, 1927) was a chemist who, along with Constantin Fahlberg discovered the artificial sweetener saccharin. He was the second president of Johns Hopkins University.
In 1879 he made the greatest discovery of his career by accident. When he ate rolls at dinner after a long day in the lab researching coal tar derivatives, he noticed that the rolls tasted initially sweet but then bitter. Since his wife tasted nothing strange about the rolls, Remsen tasted his fingers and noticed that the bitter taste was probably from one the chemicals in his lab. The next day at his lab tasted the chemicals that he had been working with the previous day and discovered that it was the oxidation of o-toluenesulfonamide he had tasted the previous evening. He named the substance saccharin and he and his research partner Constantin Fahlberg published their finding in 1880. Later Remsen became angry after Fahlberg patented saccharin, claiming that he had discovered saccharin.
In 1901 Remsen was appointed the president of Johns Hopkins and he proceeded to found a School of Engineering and helped establish the school as a research university. He introduced many of the German laboratory techniques he had learned and wrote several important chemistry textbooks. In 1912 he stepped down as president and retired to Carmel, California. After his death the new chemistry building was named after him at Johns Hopkins. His ashes are located behind a plaque in Remsen Hall; he is the only person buried on campus. According to legend, undergraduates who rub the plaque the night before their chemistry exam will do well.