Ammonia. (Fu., Ammoniaque ; Gun., Ammoniah.) Formula, We are indebted, probably, to the Romans for the name of this substance, its source being a district near Libya called Ammon, Amun, an Egyptian god, being worshipped at this place. The Egyptians were in all probability acquainted with ammonia in some form, although by what name it would be idlpoto conjecture.
Under ordinary temperatures and pressures, ammonia has all the properties of a permanent gas ; it can be liquefied and even solidified. Faraday succeeded in liquefying this gas under a pressure of six and a half atmospheres, at the temperature of 5°, into a colourless and nearly odourless liquid, which solidified into a white translucent crystalline mass at — 75°. One volume of the liquid raised to 15° at the pressure of 30.2 inches, formed 1009.8 volumes of the gas. It is very soluble in water, from which it can be again expelled by boiling; it is, however, impossible to entirely remove all the ammonia when water has once become impregnated with it.
At 0°, water takes up 1050 times its volume of the gas, and at 25° it takes up 580 times its volume, and has then a sp. gr. of 0.880. This liquid is known in commerce under the name of "Liquor Ammonia Fortiss." ; it possesses strongly alkaline properties ; diluted with three times its volume of water it forms the spirit of hartshorn of pharmacy. It mixes with the fatty oils and acids, and forms salts corresponding to those of the alkalies ; mixed with olive oil, it forms the " hartshorn and oil " of medioine, and is the basis of many stimulating embrocations ; it dissolves resins, and other vogetablo principles, forming ammoniated tinetnres and varnishes. Hatter's varnish is mado by dissolving shellac in u solution of ammonia. In some pharmacoracial pre parations it is used mixed with alcohol, for extractiog resinous or resinoidal matters ; after the extraction of the vegetable principles by this mixed solvent, the alcohol is sometimes dra wn off by distillation, as in the manufacture of a strong essence of ginger for making " giager beer," &c.
The composition of ammonia is expressed by the formula NHs, it is not extensively met with as a natural product, its chief commercial sources being the waste products obtained in the destructive distillation of animal and vegetable substances containing nitrogen, such are the " bone liquor " obtained in the preparation of animal charcoal used in sugar refining, &c., and the " gas
liquor" obtained in the destructive distillation of coal for illuminating purposes.
The more important preparations of this substance are :—The strong aqueous solution of tho gas, " Liquor Ammonia Forties." Sulphate of ammonia, used extensively as a manure, and for the production of other ammuniacal preparations. Chloride of ammonium, used for manufacturing other salts of ammonia, galvanizing, galvanic batteries, and as a flux. Carbonates of ammonia, for confectionery and medicinal uses. Sulphide, oxalate, nitrate, phosphate, and bromide of ainmoniuni used in photography, chemistry, &c. Ammonia and its compounds enter into combioation with rnany metallic substances, forming important series of double compounds, having special though limited applications to the industrial arts and manufactures.
The minor salts of ammonia are obtained by neutraliziug an acid with the carbonate, for neutral salts, or by dividing a sobition of a known weight of the carbonate into definite parts, neutra lizing one portion first, then adding the remainder for basic salts, and vice versd for acid salts. Nitrate of ammonia is employed for the production of nitrous oxide gas, which is at presout largely used by dentists. This salt should be perfectly neutral in its solution ; 4 ounces of the dry salt heated in a glass retort should yield one cubic foot of the gas at the ordinary temperature and pressure. As this gas is soluble in water, which takes up three-fourths its volume of the gas, it should be washed and colleoted over warm viater. Phosphate of soda and ammonia, or sodium ammonium hydrogen phosphate is an importaut chemical reagent for separating maguesia. The dry and fused salt is employed as a flux ; it is prepared by dissolving 6 parts of orystallized disodium hydrogen phosphate (ordinary phosphate of soda), and one part of ammonium chloride in two parts of boiling water, the double phosphate crystallizes out on cooling, and may be freed from the sodium chloride whieh is formed, by recrystallizations, from u small quantity of boiling water containing a little ammonia. Sehweitzer's solution, which is employed for dissolving and separating cotton fibres from silk, wool, &c., is made by simply dissolving the recently precipitated oxide of copper in strong liquid ammonia.