Synthesized air is produced by combining pure oxygen and nitrogen and contains between 19.5 and 23.5 percent oxygen, with the balance nitrogen and with a major portion of the other components eliminated.
Dry air is non-corrosive.
Liquefied air is transparent with a bluish cast and has a milky color when it contains carbon dioxide. Because air is a mixture, not a compound, it can be separated into its components. Air can be compressed at the point of use for most practical applications. For most practical purposes, the air composition is taken to be 78 percent nitrogen and 21 percent oxygen by volume, and to be 75.5 percent nitrogen and 23.2 percent oxygen by weight. Trace impurity levels may vary with geographic locations or with proximity to industrial areas or highways carrying dense traffic.