high pressures produces nervous irritation ("anti-anaesthesia"), suggesting that the anaesthetic mechanism(s) may be operated in reverse by this gas (i.e., nerve membrane compression). Also, some halogenated ethers (such as flurothyl) also possess this "anti-anaesthetic" effect, providing further evidence for this theory. History Paracelsus developed an inhalational anaesthetic in 1540. He used sweet oil of vitriol (prepared by Valerius Cordus and named Aether by Frobenius): used to feed fowl: “it was taken even by chickens and they fall asleep from it for a while but awaken later without harm”. Subsequently, about 40 years later, in 1581, Giambattista Delia Porta demonstrated the use of ether on humans although it was not employed for any type of surgical anesthesia. In modern medicine, Dr. Horace Wells used nitrous oxide for his own dental extraction in 1844. However his attempt to replicate these results at Massachusetts General Hospital (MGH) resulted in a partial anesthetic and was deemed a failure. William T.G. Morton is credited with successfully demonstrating surgical anesthesia for the first time on October 16th, 1846, at MGH. Following this event, the use of ether and other volatile anesthetics became widespread in Western medicine. See also A.C.E. mixture - a mixture of ethanol, chloroform and diethyl ether Anaesthetic Concentration effect Second gas effect References General anesthetics GABAA receptor positive allosteric modulators NMDA receptor antagonists