Nitrous Oxide is produced by heating Ammonium Nitrate to a temperature of approx. 250 deg.c. Ammonium Nitrate is decomposed in the process to give a mixture of Nitrous Oxide and super heated steam. Impurities include Ammonium Nitrate fumes, Nitrogen and other oxides of Nitrogen. The steam and impurities are removed by scrubbing with water, caustic soda and sulfuric acid. Nitrogen present in traces is removed by bleeding from the top of storage vessels, where Nitrous Oxide in liquid state is stored after compression.