The oldest of the hypnotic (sleep inducing) depressants, chloral hydrate was first synthesized in 1832. Marketed as syrups or soft gelatin capsules, chloral hydrate takes effect in a relatively short time (30 minutes) and will induce sleep in about an hour. A solution of chloral hydrate and alcohol constituted the infamous "knockout drops" or Mickey Finn." At therapeutic doses, chloral hydrate has little effect on respiration and blood pressure but, a toxic dose produces severe respiratory depression and very low blood pressure. Although chloral hydrate is still encountered today, its use declined with the introduction of the barbiturates.