Chloral Hydrate, an organic chemical in long use as a sedative-hypnotic drug (see Sedative). Related to chloroform, chloral hydrate is not as strong as some of the more recent drugs in this category, but administered with alcohol, the crystalline powder—the so-called “knockout drops”—can produce coma. Chloral hydrate also irritates mucous membranes and skin. As with other sedative-hypnotics, addiction may result through repeated use.