…o: 53 FR 11250 , Apr. 6, 1988, as amended at 59 FR 14364 , Mar. 28, 1994; 68 FR 24879 , May 9, 2003; 88 FR 17724 , Mar. 24, 2023] § 184.1540 Nitrogen. Nitrogen (empirical formula N , CAS Reg. No. 7727-37-9) is a colorless, odorless, flavorless gas that is produced commercially by…