{ } a. Of, pertaining, or containing ammonia, or possessing its properties; as, an ammoniac salt; ammoniacal gas. [ 1913 Webster ]

Ammoniacal engine, an engine in which the vapor of ammonia is used as the motive force. --
Sal ammoniac [ L. sal ammoniacus ], the salt usually called chloride of ammonium, and formerly muriate of ammonia. [ 1913 Webster ]

. Any fermentation process by which ammonia is formed, as that by which urea is converted into ammonium carbonate when urine is exposed to the air. [ Webster 1913 Suppl. ]