Ammoniac, the concrete juice of dorema am-moniacum, an umbelliferous plant, a native of Persia. It occurs in masses of a brownish color containing opaque, yellowish, homogeneous tears, or the same tears may be found separated. It is a gum resin with volatile oil. It has been used in medicine as an expectorant and so-called antispasmodic. In the form of a plaster it is used externally. It is allied therapeutically as well as botanically and chemically to asafœtida.