What is the history behind barbiturates? what were they first used for?

Barbituric acid: was discovered in the late 19th century and came into use in the early 20th century for the same uses as it is now - as a sedative. Various congeners were made that were used for anesthesia (thiopental), sleeping pills (nembutal, amytal), as anticonvulsant (phenobarbital). These drugs can be highly toxic and result in overdose frequently, and also cause a terrible physical dependency/addiction.