AMMONIA (supposed to be so called be. cause originally prepared from the dung e camels near the temple of Ammon, in Egypt a gaseous compound of hydrogen and nitrogen having the formula NH3. It may be forme< in small quantities by the direct combination c. its elements under the influence of the silem electric discharge; but in the arts it is com monly prepared by the decomposition of nitroc enous matter. Formerly it was manufacture< in large quantities by the destructive distillatior of horns, hoofs and hides, and from this far. it was known as °spirits of hartshorn." It 15 now chiefly obtained as a by-product in manufacture of coal-gas. Coal suitable fo the manufacture of gas contains nitrogen, oftrr: to the extent of 2 per cent of its weight ; and r the distillation of such coal the nitrogen an• bines with a portion of the hydrogen that i3 also present, and is driven off in the form or ammonia; or more often it combines with the sulphur present and js obtained in the form c: a sulphate. Salts of ammonia also occur :7 nature, sometimes in considerable quantities. In Tuscany ammonia sulphate is obtained as a by-product in the manufacture of boric acid Sec BOUSSINGAULTITE ; LARDERELLITE ; MASCAC NITE.
Ammonia (NH.) is a colorless gas at or6 nary temperatures and pressures, but at 60° F it condenses into a colorless and expansibe liquid upon the application of a pressure c about seven atmospheres. At the freezing poi: of water a pressure of 4.4 atmospheres suffice to liquefy it; and at about 29° below zero, F. it condenses into a liquid at ordinary atmos pheric pressure. Ammonia thus liquefied by pressure is much used, in the arts, for the pro duction of low temperatures and the manufac ture of artificial ice. (See REFRIGERATION). freezes at about 103° below zero, F., into a white crystalline solid. Liquid NTH, dissolve the alkali metals without chemical change forming blue solutions.
Ammonia gas is very soluble in water at or dinary temperatures, the solution constitutinz the so-called °ammonia' or °aqua ammonia' that is familiar in every household. At 32° F and at ordinary atmospheric pressure wain will absorb 1,148 times its own volume of NH,, and at 68° F. it will absorb 740 times its osa volume.
Both ammonia gas and its solution in water possess strongly alkaline properties, turning red litmus paper blue and combining with acids to produce definite salts. The solution of am monia gas in water is attended by a consider able development of heat, and it is usual to consider that a definite compound of ammonia and water is formed. The formula of this
compound may be written but many considerations suggest that NI-14.0H is a better and more logical form. NH. is here con sidered to he a radical, analogous in its chemi cal deportment to the familiar alkali metals sodium and potassium. According to this view ordinary °aqua ammonia* would be regarded as a solution of the hydrate of the radical NH.: and for many years past chemists have ad mitted the existence of .such a radical, which they have called °ammonium.* Upon adding hydrochloric acid to a solution of ammonia gas, a compound known as sal ammoniac' is obtained, which is used largely in electric bat tries that are intended for open circuit work. 'he reaction by which this substance is formed iay be written NI-13-1-HC1=NI-ILHCI; or if lie existence of a definite hydrate in the "aqua mmonia" is admitted, we may write the reac ion in which ase the reaction is in all respects analogous to hat by which potassium chlorid (for example) ; formed when hydrochloric acid acts upon otassium hydrate: KOH-FHC1=KC1-FH2O. ill the other salts that are formed by the com ination of ammonia with acids can be simi irly expressed by admitting the existence of ie radical NH4 and treating it, in the formula:, s though it were a metal of the alkali group. .11 the compounds are isomor hous with the corresponding potassium com minds.
Aqua ammonia, or ((caustic ammonia" (as it sometimes called), is used for many purposes I the arts, notably in the production of soda y the ammonia process (see Sonturd), and in yeing and calico-printing. Large quantities f the sulphate are used in fertilizers and in ie manufacture of ammonia alum (see ALUM). he chloride of ammonium is used (as above oted) in certain common forms of electric atteries, and also in soldering, in dyeing, and i many minor ways. The carbonate is largely sed in the manufacture of baking powders rid for scouring wool.
Ammonia is expelled from all of its corn ounds by quicklime, and the usual test for mmoniacal compounds consists in heating the ubstance to be examined, together with caustic me or caustic soda or potash. If ammonia is resent in any considerable amount it is berated by this treatment and may be recog ized by smell or by its action on litmus paper. (early all of the compounds of ammonia are atteries, and also in soldering, in dyeing, and le double platinic chloride being the chief ex eptions.
Ammonia forms the s•arting point for an xtraordinarily long list of compounds, many f which are exceedingly complicated. See 1MIDE; AMINE.