Nitrous oxide

Nitrous oxide, commonly known as laughing gas or sweet air,[1] is a chemical compound with the formula N2O. It is an oxide of nitrogen. At room temperature, it is a colorless non-flammable gas, with a slightly sweet odor and taste. It is used in surgery and dentistry for its anesthetic and analgesic effects. It is known as "laughing gas" due to the euphoric effects of inhaling it, a property thathas led to its recreational use as a dissociative anesthetic. It is also used as an oxidizer in rocketry and in motor racing to increase the power output of engines. At elevated temperatures, nitrous oxide is a powerful oxidizer similar to molecular oxygen.

Nitrous oxide gives rise to NO on reaction with oxygen atoms, and this NO in turn reacts with ozone. As a result, it is the mainnaturally occurring regulator of stratospheric ozone. It is also a major greenhouse gas and air pollutant. Considered over a 100 year period, it has 298 times more impact per unit weight (Global warming potential) than carbon dioxide.[2]

HistoryThe gas was first synthesized by English natural philosopher and chemist Joseph Priestley in 1772, who called it phlogisticated nitrous air (seephlogiston).[3] Priestley published his discovery in the book Experiments and Observations on Different Kinds of Air (1775), where he described how to produce the preparation of "nitrous air diminished", by heating iron filings dampened with nitric acid.[4]

[edit] Early use (1794–1843)The first important use of nitrous oxide was made possible by Thomas Beddoes and James Watt, who worked together to publishthe book Considerations on the Medical Use and on the Production of Factitious Airs (1794). This book was important for two reasons. First, James Watt had invented a novel machine to produce "Factitious Airs" (i.e. nitrous oxide) and a novel "breathing apparatus" to inhale the gas. Second, the book also presented the new medical theories by Thomas Beddoes, that tuberculosis and other lung diseasescould be treated by inhalation of "Factitious Airs".[5]

The machine to produce "Factitious Airs" comprised three parts: A furnace to burn the needed material, a vessel with water where the produced gas passed through in a spiral pipe (in order for impurities to be "washed off"), and finally the gas cylinder with a gasometer where the produced air could be tapped into portable air bags (made ofairtight oily silk). The breathing apparatus comprised one of the portable air bags connected with a tube to a mouthpiece. With this new equipment being engineered and produced already in 1794, the way was now paved for clinical trials,[clarification needed] which began when Thomas Beddoes in 1798 established the "Pneumatic Institution for Relieving Diseases by Medical Airs" in Clifton (Bristol).In the basement of the building, a large scale machine was producing the gases under the supervision of a young Humphry Davy, who was encouraged to experiment with new gases for patients to inhale.[5] The first important work of Davy was to examine the nitrous oxide, with the results being published in his book: Researches, Chemical and Philosophical (1800). In that publication, Davy notes theanalgesic effect of nitrous oxide at page 465 and its potential to be used for surgical operations at page 556.[6]

Despite Davy's discovery that inhalation of nitrous oxide could relieve a conscious person from pain, another 44 years would elapse before doctors attempted to use it for anaesthesia. The use of nitrous oxide as a recreational drug at "laughing gas parties", primarily arranged for theBritish upper class, became an immediate success beginning in 1799. While the effects of the gas generally make the user feel stuporous, dreamy and sedated, some people also "get the giggles" in a state of euphoria, and erupt in laughter and overall amusement.[7]

[edit] Anesthetic useFurther information: Nitrous oxide and oxygen
The first time nitrous oxide was used as an anesthetic drug in...