denitrate

from The Century Dictionary.

• To remove the lower oxids of nitrogen from (nitrous vitriol), in the manufacture of sulphuric acid by the lead-chamber process, so that these oxids may not be lost, but returned to the lead-chambers.
• To decompose (guncotton, nitroglycerin, or other nitric esters used as explosives), removing the nitric-acid radical and regenerating the cellulose, glycerin, etc., from which these were produced.
• To free from nitric acid.