AMMO NIA, the modern name of the vola tile alkali, formerly so called to distinguish it from the more fixed alkalies it is a gaseous body, and was first procured in that state by Priestley, who termed it Alkaline air. He obtained it from sal ammoniac, and hence the present name of the alkali.
Ammonia, like all the other alkalies, is a compound substance ; it consists of nitrogen and hydrogen, in the proportion of one atom of the former to three of the latter; but these two cannot be made to combine by direct action. 'Ammonia is colourless, transparent, and of course invisible ; possessing the elas ticity and mechanical properties of atmosphe.. fie air. `1:he smell is peculiar and extremely and its taste is highly acrid. An animal hut into it is immediately killed, arid a taper when inuncrsed in it is extinguished. The density of ammoniacal gas is to that of atmospheric air, nearly as 0.5902 to 1; 100 cubic males weigh rather more than 18 grains. It acts strongly as an alkali, turning vegetable blues green, and yellows reddish brown, and saturates acids, forming various salts: The aqueous solution is colourless, transparent, and has the pungency and alkaline property of the gas : by exposure to the air the ammo nia escapes, and by the application of heat it is expelled froM the water.
Ammonia is produced in many different ways, both natural and artificial. Almost every animal substance contains the elements of ammonia; and when such a substance is exposed to decomposition, oxygen and carbon combine to form carbonic acid, while hydrogen and nitrogen form ammonia; and the two to gether form carbonate of ammonia. If such substances as bones, hoofs, or horns, are heated in iron cylinders, ammonia is separa ted in combination with many other matters, and, after purifying, a liquid called spirit of hartshornresults. Vegetable matter containing
gluten, coal-soot, and coal itself, may also be made to yield ammonia. Ammonia is produced in small quantities by many different chemical processes, but those mentioned above are the chief sources. By the heat of a spirit lamp, ammonia forms with sodium pr potassium a yellowish crust of those metals, though the surfaces remain brilliant and smooth. When passed over melted iron or copper, ammonia is absorbed ; and by voltaic action ammonia may be made to combine with mercury, pro clueing an amalgam which is soft at 70° or 80°Talirenbeit, but a firm crystalline body at 32°. Ammonia combines with many of the metals to form anzmoniurets. In many of its practical applications ammonia is used in solution in water, called liquid ammonia, as being more convenient than in the gaseous form.
Ammonia produces many valuable salts, when combined with acids; and those salts, as well as liquid ammonia itself, play an im portant part in many chemical manufactures, but still more in medicine. The carbonate of ammonia is much used by the bakers of fancy bread and light pastry. With a few drops of any aromatic essential oil it forms smelling salts. Crude sulphate of ammonia forms ex cellent manure. Nitrate of ammonia forms a freezing mixture with water. Iduriate of am monia is employed in dyeing ; it is also used to impart pungency to snuff.