Saccharin

The artificial sweetener in "Sweet'N Low," is somewhere around 400 times sweeter than sugar. It was discovered in 1879 by Constantine Fahlberg who was actually working on substitution products of coal tar.

After a long day in the lab, he forgot to wash his hands before eating dinner. When the bread and everything he touched tasted sweet, he remembered he spilled a chemical on his hands earlier.
Fahlberg patented saccharin in 1884 and began mass production.

The artificial sweetener became widespread when sugar was rationed during World War I. In 1907 diabetics started using the sweetener as a replacement for sugar and it was soon labeled as a noncaloric sweetener for dieters. Because the body can not break it down, we do not get any calories.