182 AMMONIA,

(15°’5 C.), at a barometric pressure of 80-2 inches, itformed 1009 - 8 volumes of the vapour.

Faraday succeeded in obtaining ammonia in thesolid state by exposing the gas to the pressure of20 atmospheres, whilst reduced in temperature bysurrounding the vessel with a mixture of solid car-bonic' acid and ether.

Ammonia is decomposed with facility by-heat inthe presence of any substance which contains oxygeneasily transferable; hence, if the higher oxidizedcompounds of nitrogen be brought into contact withammonia, and both compounds are mutually decom-posed, water and a lower oxide, with the occasionalelimination of nitrogen, are the result. When trans-mitted over many metallic oxides at a dull red heat,it is decomposed into nitrogen and hydrogen; thelatter abstracting oxygen from the oxide and formingwater. It is also split up into its constituent gasesby a succession of electric sparks.

LIQUID AMMONIA.— Aqueous Ammonia. Sal-miakgeist, G erman; esprit de sal ammoniac, French ;synonymous with caustic ammonia and spirit of harts-horn. Formula, NH 4 0.—The preparation of liquidammonia is one among the many manufactures whichhave sprung up in consequence of the rapid progressof science and art during the last half century; butit seems to have risen to its present state simultane-ously w r ith that of gas-lighting. Considerable quan-tities of crude liquor ammonia are produced as oneof the by-products of the distillation of coal; hencethe establishment of factories for the preparation ofammonia and its salts has gradually taken place, fromthe metropolis to almost every provincial villagewhere gas is consumed. The demand for animalcharcoal opened another extensive supply of ammonia,for it is evolved during the destructive distillation ofthe bones from which the animal charcoal is pre-pared for the sugar refiner and others ; and as soonas the spirit of enterprise and emolument inducedthe capitalist to turn his attention to the manufac-ture, various other sources were discovered whichyielded this alkali. The principle on which am-monia is generated on the large scale differs innothing from the processes already stated ; and theformation of the solution of the alkali rests upon theproperty which water possesses of absorbing it.Water, at a temperature of 60° Fahr. (10° C.), con-denses about 070 times its bulk of ammoniaeal gas,Davy (i.e., nearly half its weight), 780 according toThomson ; by this retention the bulk of the solutionis increased considerably, so much so, that 6volumes of water, on becoming saturated with thegas, increase to 10 volumes, and the specific gravityof the liquid is reduced from TOO to 0 - 875.

Liquor ammonia is prepared in the laboratory bytaking a mixture of 1 part of sal ammoniac with Im-part of slaked lime, and 1| part of water, andintroducing it into a glass or earthenware retort, theneck of which is connected with a series of Woulfe’sbottles, described at page 78—one of which con-tains a little water to arrest impurities; the second,a weight of water equal to that of the ammoniumchloride used, space being allowed for expansion of

-Preparation.

the liquid; a third is useful to stop the uncondensedammonia which would otherwise escape into the air.The ammoniaeal solution in the last two bottles ispure. It is necessary that the lime used should boslaked in about 4 parts of water, previous to itsbeing mixed with the powdered ammoniaeal salt, asby that means the ammonia will be more freely dis-engaged, and with less heat than when only a smallquantity of moisture is present.

Fig. 2 is a representation of an apparatus whichanswers the purpose remarkably well.

During the decomposition the heat should not betoo briskly applied, and in no case should the bottomof the retort be raised to redness, as portions of thesalt would be sublimed without being decomposed;and by passing over to the first bottle, would renderits contents unfit for use. To guard as much aspossible against the sublimation of the salt, the tubeconnecting the retort and first bottle should have aconsiderable calibre; and it is often advantageous toappend a large bulb or balloon between the mouthof the retort and first condenser, in order that anyportion of the sublimed salt which might be drivenoff towards the end of the operation, may be arrested

Fig. 2.

before it is carried into the ammoniaeal liquor. Thegreatest precaution is to be taken in having all theconnections air-tight, to prevent the escape of vapour.When the whole of the ammonia is driven off, it isnecessary to raise the temperature a little higherthan usual to fuse the chloride of calcium; and assoon as this takes place, the retort should be disjoinedfrom the condensing bottles, and the fused saltpouredout as speedily as possible. Very often the retortbreaks at this part of the operation, in consequenceof a layer of the salt solidifying upon its neck, whichon being exposed to the air readily absorbs moisture,and partly dissolves; the solution thus formed coolsconsiderably, and on penetrating through the undis-solved portion of chloride of calcium to the retort,which still retains a high degree of heat, the particleswith which it comes in contact are suddenly con-tracted, and the. retort cracks. Should the retortescape fracture at this part of the process, it generallyhappens that it is broken when the heat is appliedfor a second operation; hence it is rare to find a retort,even when carefully handled, that will stand twooperations.

Uses of Ammonia .—Ammonia is in daily requisitionas a reagent for the analytical chemist. It offers