QUALITIES. _Form_, masses composed of fragments, of tears, yellow on the surface, and white within; _Taste_, a nauseous sweet, followed by a bitter flavour; _Odour_, faint but not unpleasant. _Specific gravity_, 1·200. CHEMICAL COMPOSITION. Gum-resin, gluten, and some volatile matter. SOLUBILITY. It is partly soluble in water, vinegar, alcohol, æther, and in the solutions of the alkalies; when triturated with water a milky liquor is formed, which is a solution of gum holding the resin in suspension, and if the yolk of an egg be employed the mixture is more permanent; water appears to be its proper solvent. USES. Stimulant, antispasmodic, and expectorant: in large doses gently purgative and sometimes diuretic; after the exhibition of smart purgatives, in combination with rhubarb, it proves valuable in mesenteric affections by correcting the viscid secretion of the intestines; dissolved in nitric acid, it is said to prove an excellent expectorant in cases where large accumulations of purulent or viscid matter exist with feeble and difficult expectoration. See _Form: 140_. FORMS OF EXHIBITION. In solution, see _Mist: Ammoniac:_ it may also be given when dissolved in the _Liquor ammoniæ acetatis_; ʒij of the former may be dissolved in ℥iij of the latter; or it may be exhibited in pills with bitter extracts, myrrh, and other gum-resins; if rubbed with camphor a mass is at once produced very suitable for pills; vinegar renders it soft, and adapts it for plasters. DOSE, grs. x to xxx. OFFICINAL PREPARATIONS. _Mist: Ammoniac:_ L.D. _Pil: Scillæ co:_ L.E. (=B=) _Emplast: Ammoniac:_ L. _Emplast: Gummos:_ E. _Emplast: Ammoniac: cum Hydrargyro_. L. ADULTERATIONS. Two varieties are met with in the market, that in tears, _guttæ ammoniaci_, ought to be white, clear, and dry; and that in lumps, _lapis ammoniaci_, which sells for one-third the price of the former, being very impure, is generally adulterated with common resin, for which it may be purified by softening the mass in a bladder which is immersed in boiling water, and straining it while fluid. AMMONIÆ SUB-CARBONAS. L. Carbonas Ammoniæ. E.D. _Sub-carbonate of Ammonia._