A body occurring in small quantity in the juices of muscle, in the lungs, and elsewhere, but especially in the bile, where it is found as a component part of taurocholic acid, from which it can be prepared by decomposition of the acid. It crystallizes in colorless, regular six-sided prisms, and is especially characterized by containing both nitrogen and sulphur, being chemically amido-isethionic acid, C2H7NSO3.