Editing Newcomen atmospheric engine (section)

====Snifting valve====
Newcomen found that his first engine would stop working after a while, and eventually discovered that this was due to small amounts of air being admitted to the cylinder with the steam. Water usually contains some dissolved air, and boiling the water released this with the steam. This air could not be condensed by the water spray and gradually accumulated until the engine became "wind logged". To prevent this, a release valve called a "snifting clack" or snifter valve was included near the bottom of the cylinder. This opened briefly when steam was first introduced, and non-condensable gas was driven from the cylinder. Its name was derived from the noise it made when it operated to release the air and steam "like a Man snifting with a Cold".<ref>"A Course of Experimental Philosophy", John Theophilus Desaguliers, 1744, Vol II p. 474.</ref>