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428 AMMONIAC ratus, and to liquefy mucus where they come in contact with it, either directly as in the stomach and intestines, or in the way of elimi- nation, as in the bronchial tubes. It leaves the system by the lungs, skin, and kidneys, having much less effect than the fixed alkalies in alka- lizing the secretion of the latter organ. Car- bonate of ammonia is used as a rapidly diffu- sible stimulant in various diseases, especially febrile and neuralgic, and sometimes as an ex- pectorant, its action being twofold, strengthen- ing the bronchial muscles and liquefying the mucus. The chloride, though it is less pow- erful as a stimulant, is used for similar pur- poses, and also in some affections of the diges- tive organs. The liquor ammonite acetatis or spiritus Mindereri is, in the doses usually given, but little more than a placebo. Ammonia, in the gaseous or liquid form, has been proposed as an antidote to several poisons, especially alcohol, carbonic acid, and prussic acid. For these purposes the stimulant action is desired, but the gas must be used with great caution on account' of its irritant effect on the air passages. The injection of ammonia into the veins, as a cure for the bite of venomous serpents, has been practised by Prof, llalford of Australia, and others on his recommendation. Although recoveries have been reported, the question of its efficacy must be regarded as still unsettled. 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, homogene- ous tears, or the same tears may be found sep- arated. 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 thera- peutically as well as botanically and chemical- ly to asafbetida. AMMONITES, a genus of fossil shells allied to the nautilus. The fossils are in the form of a coil or of a fam's horn, and the name is given to them from their resemblance to the horns upon Ammonites Jason. the statues of Jupiter N Ammon. They also resem- ble a snake in its coil, and are generally supposed by the common people to be petrified snakes. The animal that inhabited the shell was pro- vided with air chambers, by means of which it could rise or sink in the water ; and its shelly covering, necessarily very delicate in order to float, was made strong to bear the pressure at AMMONIUM great depths by its tubular form and by the ribs or plates of shell that supported it within. From the lower rocks of the transition period up to the tertiary, the ammonite has been rep- resented by many species. They abound espe- cially in the oolite. They appear to have been Ammonites Nodotianus. very widely distributed over the ancient seas, the same fossil species being found in rocks of the same period in different quarters of the globe. They are common in the greensand Ammonites Cordlfonnis. formation in New Jersey, and far up the Mis- souri river. In Asia, at an elevation of 16,000 feet, in the Himalaya mountains, some of the same species have been found that are met Ammonites Tornatnu. with in England, and one of the same in the Maritime Alps, 9,000 feet above the sea. They are so abundant in some parts of Bur- gundy that the roads are paved with them. In the chalk formation they are found of gigantic size, three and even four feet in diameter. AMMONIUM, the hypothetical radical of am- monia, supposed to be metallic. What is called an amalgam of mercury and ammonium was first obtained by Berzelius and Pontin from the