AMMONIA.— Preparation.

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structive distillation, yields it in moderate abundance;it is also found united with acids in many strata ofthe mineral kingdom. In the atmosphere, veryminute portions of ammonia are always present,which exert a most beneficial influence upon vegeta-tion. Volcanic districts are highly productive ofammonia, standing second in this respect only to theguano islands of South Africa , Sea water containsa low decimal percentage of ammoniacal salts; freshwater also holds it in combination, but in an infini-tesimal proportion. A perceptible quantity of thisalkali, generally combined with acids, is found inmineral springs; soils almost universally contain it—more especially those of the ferruginous and argillace-ous class. In many substances where ammonia isapparently absent, a careful and patientinvestigation may prove its presence.

Thus, it occurs in the atmosphere;apparently no ammonia exists in it whenperforming an analysis, but on examin-ing rain water recently collected in townor country, an expert chemist will alwaysdetect it in minute quantity.

Animal excrements, especially those ofreptiles, are rich in ammoniacal com-pounds.

Preparation. —It may be prepared inthe laboratory by a very simple process,namely, by heating an ammoniacal saltwith quicklime in a retort, and collect-ing the eliminated alkaline vapour overmercury, or by displacement of air. Thisoperation, though simple, requires—likeall those conducted on the small scale—care and skill to obtain a pure product.

The decomposition which takes place inthe preceding instance, supposing thatammonium chloride had been employed, is thefollowing:—■

Ammonium Chloride. Lime. Ammonia. Calcium Chloride. Water.

2NH 4 C1 + CaO = 2NH 3 + CaCI 2 + lf 2 0.

The arrangement in Fig. 1 is well adapted forthe preparation of ammoniacal gas: equal weights ofthe ammonium chloride and quicklime which has beenjust slaked are intimately mixed, and introduced intothe retort, heat is applied, gently at first, and thengradually increased till the gas ceases to be evolved—calcium chloride remains.

One volume of nitrogen and three volumes ofhydrogen cannot be made to unite directly, evenwhen passed over red-hot spongy platinum. But onigniting a mixture of hydrogen (in excess), nitrogen,and oxygen, ammonium nitrate is formed.

In a chemical point of view, ammonia is generatedin various and curious ways; as, when an excess ofhydrogen is burned in the atmosphere, nitrate ofammonia is formed; when iron oxidizes, from thedecomposition of water, sesquioxide of iron and am-monia result. A similar combination is formed whenhydrates of potassium, sodium, barium, or calcium,are heated in the air, or in hydrogen, with iron, zinc,lead, tin, or arsenic. According to Faraday, this

combination takes place even in an atmosphere ofhydrogen. Reiset explains its formation in hydrogenas arising from nitric oxide derived from the sulphuricacid used to prepare the hydrogen, and adduces asa corroboration the fact that when iron filings areheated in astrong solution of potassium hydrate, theyevolve hydrogen and ammonia, both when heated inair and in hydrogen containing nitric acid, but not inpure hydrogen. When nitrous oxide and an excessof hydrogen are transmitted over platinum black—spongy platinum—in the cold, no ammonia is formed;but if heat be applied it is produced in considerablequantity. A dilute solution of nitro-sulpimric acid—composed of 100 volumes of water, 41 of sul-phuric acid, and 4 of nitric acid—dissolves iron, zinc,

Fig. 1.

or tin, without giving off nitric oxide or hydrogen,although these bodies always result from the decom-position of nitric acid and the solution of the fore-mentioned metals; but in this instance the nascenthydrogen combines with the nitrogen of the nitricoxide, and gives rise to ammonia.

Ammonia is a volatile, irrespirable gas, thoughwhen diluted with air it may be inhaled. Its odouris extremely pungent; it possesses a strong alkalinetaste ; turns reddened litmus paper blue, and tur-meric paper brown; is very slightly inflammable,and extinguishes those bodies which are in a stateof combustion. It is composed of two volumes ofnitrogen and six of hydrogen, condensed into fourvolumes of the gas. The specific gravity of the gasis '5893, air being taken as unity.

By a pressure of 6) atmospheres, at the ordinarytemperature, it is condensed into a transparentcolourless liquid, of 0’731 specific gravity at 60°Fahr. (15°-5 C.); a like result is obtained at theordinary pressure of the atmosphere, by reducingthe temperature 40° Fahr. below zero (—39°9 C.).It is a very subtle, colourless liquid, which, accord-ing to Faraday, freezes into a white translucentcrystalline substance at —108° Fahr. (—57°-l C.).Ou heating one volume of the liquid to C0° Fahr.

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