In 1848, Louis Pasteur became the first scientist to discover chirality and enantiomers while he was working with tartaric acid. During the experiments, he noticed that there were two crystal structures produced but these structures looked to be non-superimposable mirror images of each other; this observation of isomers that were non-superimposable mirror images became known as enantiomers. A couple years later, in 1857, Pasteur then discovered enantioselectivity when he noticed that the two enantiomer structures he had previously discovered metabolized at much different speeds. This suggested that one configuration was preferred over the other in vivo. As organic chemistry knowledge became more advanced, the discovery of enantioselectivity was used in the creation of enantiopure drugs.