of 900,

cent.

per cent.

------------+------------+----------------+------------ 9000

100

26500

73500 9045

95

25175

74825 9090

90

23850

76150 9133

85

22525

77475 9177

80

21200

78800 9227

75

19875

80125 9275

70

18550

81450 9320

65

17225

82775 9363

60

15900

84100 9410

55

14575

85425 9455

50

13250

86750 9510

45

11925

88075 9564

40

10600

89400 9614

35

9275

90725 9662

30

7950

92050 9716

25

6625

93375 9768

20

5300

94700 9828

15

3975

96025 9887

10

2650

97350 9945

5

1325

98675 ------------+------------+----------------+------------

? Strengths corresponding to sp. gr. which are not in the above _Tables_ may be found by the 'method of differences' explained under ALCOHOLOMETRY.

? The sp. gr. of any sample of liquid ammonia, expressed in three integers, deducted from 998, and the remainder divided by 4, gives a number which represents the per-centage strength, nearly. (Ure.) This rule may be sometimes conveniently employed for rough calculations, in the absence of _Tables_.

=Ammonia, Carbonates of.= (B. P.) _Syn._ AMMONIae CARBONAS. See AMMONIUM, SESQUICARBONATE OF.

TABLE II.--_Exhibiting the relations between the_ SPECIFIC GRAVITY _of Solution of Ammonia and the_ PER-CENTAGE STRENGTH, _for every variation of 00125 sp. gr., from 87500 to 100000, at_ 62 Fahr. Abridged from the larger _Table_ of Mr J. J. GRIFFIN.

----------+------------+----------+------------+----------+------------ Sp. Gr. of

Pure Ammonia

Sp. Gr. of

Pure Ammonia

Sp. Gr. of

Pure Ammonia the Liquid

per cent.,

the Liquid

per cent.

the Liquid

per cent., Ammonia.

by Weight.

Ammonia.

by weight.

Ammonia.

by weight.

----------+------------+----------+------------+----------+------------ 87500

34694

91750

21837

96000

10119 87625

34298

91875

21477

96125

9790 87750

33903

92000

21118

96250

9462 87875

33509

92125

20760

96375

9135 88000

33117

92250

20403

96500

8808 88125

32725

92375

20046

96625

8483 88250

32335

92500

19691

96750

8158 88375

31946

92625

19337

96875

7834 88500

31558

92750

18983

97000

7511 88625

31172

92875

18631

97125

7189 88750

30785

93000

18280

97250

6867 88875

30400

93125

17929

97375

6547 89000

30016

93250

17579

97500

6227 89125

29633

93375

17231

97625

5908 89250

29252

93500

16883

97750

5590 89375

28871

93625

16536

97875

5273 89500

28492

93750

16190

98000

4956 89625

28133

93875

15846

98125

4641 89750

27736

94000

15502

98250

4326 89875

27359

94125

15158

98375

4011 90000

26984

94250

14816

98500

3698 90125

26610

94375

14475

98625

3386 90250

26237

94500

14135

98750

3074 90375

25865

94625

13795

98875

2763 90500

25493

94750

13456

99000

2453 90625

25123

94875

13119

99125

2144 90750

24754

95000

12782

99250

1835 90875

24386

95125

12446

99375

1527 91000

24019

95250

12111

99500

1220 91125

23653

95375

11777

99625

914 91250

23288

95500

11444

99760

609 91375

22924

95625

11111

99875

304 91500

22561

95750

10780

100000

{ 0 91625

22198

95875

10449

{or Water.

? The specific gravity of mixtures of pure solution of ammonia and pure water is precisely the mean of the specific gravities of their const.i.tuents. (Davy; Dalton; Christison.) In all solutions of ammonia, a quant.i.ty of anhydrous ammonia, weighing 212-1/2 gr., displaces exactly 300 gr. of water, and reduces the sp. gr. of the liquid to the extent of 00125.

(Griffin.) The strongest solution of ammonia which it is possible to prepare at 62 Fahr. has the sp. gr. 87500, and contains 34694% of pure ammonia, by weight, or 21,251 gr. per gallon. (Griffin.)[46]

[Footnote 46: Mr Griffin, in his 'System of Ammonimetry,' calls every 212-1/2 gr. of anhydrous ammonia a TEST-ATOM; and every 7 water gr.

measure, a SEPTEM. Thus, a gallon of water (= 10 _lbs_) contains 100,000 septems. The degrees of his AMMONIA-METER range from 1 to 100, and indicate the number of test-atoms of ammonia in one _gal_. of the liquid.]

=AMMONIUM.= The name given to a group of atoms, which play the part of a compound basic, radical, or metallic element. This substance, whose formula is NH_{4} or (NH_{4})_{2}, has never been isolated, although capable of forming most stable salts with the various acid radicals.

Several attempts have been made, however, to obtain this compound radical, or group of elements, in a free state, and with more or less success, but on account of its great instability it invariably decomposes when set free into ammonia and hydrogen.

Ammonium salts are some of the most important chemical agents, and are usually recognised as follows, ammonia solution, however, usually acting in exactly the same manner as a solution of ammonium hydrate:--By imparting a deep blue tint to solutions of salts of copper. By exhalation of ammoniacal gas (recognised by its odour), when triturated or mixed and heated with caustic pota.s.sa, soda, or lime. Added to a solution of bichloride of platinum, they produce a heavy yellow, crystalline precipitate, consisting of minute octahedrons easily discernible under the microscope. With protonitrate of mercury, a black precipitate. With bichloride of mercury, a heavy, white precipitate. With a concentrated solution of tartaric acid, a crystalline, white precipitate, nearly similar to that given with salts of pota.s.sa. They are nearly all soluble in water, volatile, and crystallisable.

Except the carbonate, they are almost invariably estimated by conversion into ammonia, and estimation by volumetric a.n.a.lyses, as in alkalimetry. In the laboratory, however, for exact purposes, they are converted into the double chloride of ammonium and platinum.

=Ammonium Salts:--=

=Ammonium, Acetate of.= NH_{4}C_{2}H_{3}O_{2}. _Syn._ AMMO"NIae ACE'TAS, L.; ACETATE D'AMMONIAQUE, Fr.; ESSIGSaURES AMMONIAK, Ger. _Prep._ 1. Take of acetate of lime or of pota.s.sa and sal ammoniac, equal parts; mix and distil at a gentle heat. The oily liquid (BINACETATE OF AMMONIUM, HNH_{4}(C_{2}H_{3}O_{2})_{2}), in the receiver forms a radiated crystalline ma.s.s on cooling. Dry gaseous ammonia pa.s.sed into this salt, melted by a gentle heat, transforms it into the solid and inodorous neutral acetate, NH_{4}C_{2}H_{3}O_{2}.

2. Strong acetic acid is saturated with ammonia or carbonate of ammonium, and the solution evaporated over sulphuric acid in vacuo; the resulting crystals, after being carefully drained, are dried by pressure between bibulous paper.

_Prop., &c._ Long, slender crystals, or a crystalline ma.s.s, freely soluble in both alcohol and water, and deliquescent in the air; taste sharp and cooling, and somewhat sweetish. Its solutions cannot be evaporated without loss of the ammonia; even the salt pa.s.ses off in large quant.i.ties with the vapour of water. Its aqueous solution becomes alkaline on keeping, from decomposition of the acid. Distilled with anhydrous phosphoric acid, it is converted into ACETONITRILE. An aqueous solution of this salt was introduced into the Materia Medica by Boerhaave, and has since been extensively used as a diaph.o.r.etic and febrifuge, under the popular name of MINDERERUS SPIRIT, after Minderer or Mindererus, who extensively employed it and extolled its virtues. When pure, both the salt and its solutions are neutral to test-paper, and are wholly volatilised by heat. See SOLUTIONS.

=Ammonium, a.r.s.eniate of.= (NH_{4})_{3}AsO_{4}. _Syn._ AMMONIae a.r.s.e'NIAS, L. _Prep._ 1. (NEUTRAL.) Saturate a warm concentrated solution of a.r.s.enic acid with carbonate of ammonium in slight excess; evaporate by a gentle heat, that crystals may form on cooling.

2. =Ammonium, Bina.r.s.eniate of.= H(NH_{4})_{2}AsO_{4}. As above, but adding an additional equiv. of the acid, as soon as any excess of ammonia has been expelled by the heat employed to evaporate the solution.--_Dose_ (of either). 1-24th to 1-12th gr.; in phthisis, certain skin diseases, &c. See SOLUTIONS (and _below_).

=Ammonium, a.r.s.enite of.= NH_{4}AsO_{2}. _Syn._ AMMONIae AR'SENIS, L.

_Prep._ From a hot concentrated solution of a.r.s.enious acid, and sesquicarbonate of ammonium, as the last.--Used (chiefly) to make a.r.s.enite of iron. The properties and physiological effects of the above a.r.s.enical preparations are for the most part similar to those of a.r.s.eniate and a.r.s.enate of pota.s.sa. They are all poisonous.

=Ammonium, Benzoate of.= _Prep._ 1. Dissolve benzoic acid in ammonia solution to saturation, then further add ammonia in slight excess, and crystallise by refrigeration, or in vacuo.

2. (LIQUID; SOLU'TIO AMMONIae BENZOA'TIS, L.) As the last, but without evaporating the solution.

_Prop., &c._ Very soluble and very difficult to crystallise. If the solution is boiled for a short time and then abandoned to spontaneous evaporation, crystals of ACID BENZOATE OF AMMONIUM are deposited. It is used chiefly as a chemical test; but has been recently recommended in chronic bronchitis, old coughs, &c.; and to check the formation of chalk-stones and urinary calculi.--_Dose_, 10 to 15 gr.; (of the solution) 15 drops to 1 fl. dr., or more. See BENZOIC ACID.

=Ammonium, Bromide of.= NH_{4}Br. _Syn._ AMMO"NII BROMI'DUM, A. BRO'MIS, L.; HYDROBROMATE D'AMMONIAQUE, BROMURE D'AMMONIUM, Fr. A salt which is obtained from hydrobromic acid, bromide of iron, &c., by similar processes to those adopted for the iodide. The following process for the preparation of bromide of ammonium is from the formula for the new medicaments adopted by the Paris Pharmaceutical Society: "Add bromine very slowly to a solution of ammonia, with continual stirring, until the liquid remains faintly and persistently coloured by a slight excess of bromine." It forms white prismatic crystals; and, in its general properties, resembles bromide of pota.s.sium. It is volatile, and easily decomposed.

Used as a nervine in hysterics; especially useful for sleeplessness where there is no organic disease; given in epilepsy when bromide of pota.s.sium fails.--_Dose_, 2 to 20 grains.

=Ammonium, Carbonates of=[47]--

[Footnote 47: For complete information respecting the various carbonates of ammonia consult Dr Divers' papers in the 'Journal of the Chemical Society.']

=Ammonium, Carbonate of.= _Syn._ NEUTRAL CARBONATE OF AMMONIUM. Equal parts of dry sal ammoniac and sodium carbonate are heated to form the neutral ammonium carbonate of commerce, which sublimes. Solid crystalline substance, with a strong ammoniacal odour, volatile and soluble.

_Uses, &c._ In the solid form it is not now used in medicine; but it is indirectly employed in several liquid preparations in which the sesquicarbonate is ordered. It is superior to any other preparation of ammonia for filling smelling bottles; as it is not only more pungent, but does not lose its pungency by keeping. It volatilises more quickly than the sesquicarbonate, and the residuum, unlike that of the latter salt, continues as odorous as ever. It is the basis of several of the most popular and esteemed advertised smelling salts of the shops. Spirit of hartshorn is an impure solution of this salt, originally obtained by distilling hartshorn or bones.

=Ammonium, Sesquicarbonate of.= Probably 2NH_{4}HCO_{3} + NH_{4}NH_{2}CO_{3}, _i. e._ a mixture or compound of bicarbonate of ammonium and carbamate of ammonium. _Syn._ (CARBONATE OF AMMONIA, AMMONIae CARBONAS. B. P.). CARBONATE D'AMMONIAQUE, Fr.; KOHLENSAURES AMMONIAK, Ger.

It is prepared on a very large scale commercially as follows:--Sal ammoniac or sulphate of ammonia, and chalk, equal parts, both dry and in powder, are mixed as before, and sublimed from a series of iron retorts or iron pots, into a well-cooled and capacious receiver lined with lead or earthenware; or, more generally, into such a receiver connected, by iron or lead pipes, with a second and similar one containing a stratum of water, to absorb the free ammonia evolved during the process.

The so-called "Volcanic Ammonia" is evolved during the manufacture of borax, from carbonate of soda and boracic acid. It is largely used in pharmacy.

_Prop._ The carbonate of ammonia, of commerce, usually occurs in the form of white, fibrous, translucent, or semi-translucent cakes, generally about two inches thick. It is less volatile and pungent than the neutral carbonate; soluble in 4 parts of water at 55 Fahr., 33 parts at 62, 25 parts at 96, and 2 parts at 120; boiling water and alcohol decompose it, with the evolution of carbonic acid gas and ammonia; by age or exposure to air, the surface a.s.sumes an opaque white colour, from its carbonate flying off, and the remaining bicarbonate being less volatile. Unlike the carbonate, it can neither be resublimed nor digested or distilled with either alcohol or water, without suffering decomposition. Sp. gr. 0966.

The exact composition of this salt varies, according to its method of preparation.

_Uses, &c._ It is commonly employed by bakers to give lightness to their fancy goods, and to make extemporaneous bread and pastry; by the chemist and pharmaceutist, for the preparation of other salts of ammonia, and in a.n.a.lysis, &c. In _medicine_ it is used as a stimulant, antispasmodic, antacid, and diaph.o.r.etic, in acidity of the stomach, dyspeptic affections, gout, scrofula, hysteria, lowness of spirits, epilepsy, &c.; and in the convulsions attending dent.i.tion. It has been recently recommended, by Dr Barlow, in diabetes. It is also employed to make effervescing draughts; and externally as a counter-irritant and stimulant. Its use as a nasal stimulant in headaches, fainting, &c., is well known. In large doses it is emetic; in excessive doses poisonous. Its long-continued use, in quant.i.ty, is often productive of very serious consequences--slow fever, debility, emaciation, scurvy, loss of teeth, haemorrhage, general cachexy, and even death. The antidote and restorative treatment are, the free use of lemon-juice, wine or malt-liquors, new milk, and antis...o...b..tic vegetables, with a generous diet, of which the red meats form a large proportion.--_Dose._ As a stimulant or diaph.o.r.etic, 5 to 15 gr., dissolved in cold water; as an emetic, 20 to 30 gr., in tepid water, repeated if necessary; as an effervescing saline draught, 15 to 30 gr. A few grains (8 or 10) dissolved in a tumbler of cold water is an excellent 'refresher' in lowness of spirits, or after fatigue; and is highly esteemed by drunkards; being, in each case, preferable to 'spirit of sal volatile,'--_Doses for Animals._ HORSE: 1 to 2 drachms. CATTLE: 2 to 4 drachms. SHEEP: 20 grains to 1 drachm. PIG: 20 grains to 1 drachm. DOG: 3 to 10 grains; in bolus, pill, or cold gruel.

_Concluding remarks, Patents, &c._ In extension of the above it may be added that, on the large scale, the distillation is usually carried on in cast-iron retorts, similar in size, shape, and character to those employed in the manufacture of coal-gas, and of which five, or more, are commonly set horizontally in the same furnace. (See _engr._) Each retort has its mouth (_a_), through which the 'charge' is introduced, closed with a movable door, which is securely fastened in its place, in the manner shown in the engr.; and is furnished, at the upper part of its further end, with an iron pipe (_c_), to carry off the evolved vapours to the condenser or receiver. The latter consists of two large square wooden chambers (_B, C_), lined with lead, and either fitted with movable covers, secured by water-joints, or with doors in the side, to permit of the easy removal of the sublimed salt. The first receiver communicates with the second by means of a large lead tube (_d_) near its centre, and by another tube (_d'_), somewhat smaller, and nearer the bottom, but above the surface of the stratum of water in the second receiver, before alluded to. These chambers have also a lead pipe (_e, e_), stopped during the process with a plug or c.o.c.k of lead, to allow of the liquid product of the distillation, &c., to be drawn off, or run into another receiver or cistern, at will.

Both chambers are placed on strong wooden supports, or scaffolding, to bring them on a level with the retorts. When the impure sulphate or other ammonia-salt is used in the manufacture of the sesquicarbonate (which is generally the case), the resulting salt being impure and discoloured, is resublimed in iron pots (_f, f, f_), furnished with movable leaden heads, which are kept cool by a current of air pa.s.sing over them; a little water being introduced into the subliming pots to render the product translucent. The heat is applied either by means of a flue pa.s.sing from the retort-furnace (_A, b_), or by a water bath heated in the same manner; the latter being the preferable method, as the temperature should not be greater than about 200 Fahr., and need not exceed 150 to 155. These pots are arranged in sets, as shown at _D_ in the engraving.

[Ill.u.s.tration]

The charge of a retort usually consists of about 70 to 72 _lbs._ of sulphate of ammonia or 57 to 58 _lbs._ of the hydrochlorate to 1 _cwt._ of chalk; or in these proportions. The product is about 40 _lbs._ of the crude salt, which, by careful resublimation, yields about 39 _lbs._ of marketable carbonate of ammonia.

Carbonate of ammonia, like the chloride and sulphate, is now scarcely ever prepared on the small scale, that of commerce being not only cheaper, but sufficiently pure for all the purposes of medicine and the arts.

=Ammonium, Bicarbonate of.= HNH_{4}CO_{3}. _Prep._ By digesting cold water on sesquicarbonate of ammonia in considerable excess, until the whole of the pungent neutral carbonate is dissolved out. If the salt is reduced to powder the operation is facilitated.

To powdered sesquicarbonate of ammonia add boiling water just sufficient to dissolve it, and immediately close the vessel; crystals form as the liquid cools, containing 2-1/2 equiv. of water.

_Prop., &c._ For the most part similar to the sesquicarbonate, except in having a taste and smell which is only faintly ammoniacal, and hence more palatable. Crystallises in oblique prisms, which, as usually obtained, contain about 23% of water. It requires 8 parts of cold water to dissolve it. It is distinguished from the previous carbonates by the almost entire absence of ammoniacal odour, and by its solution giving no immediate precipitate with chloride of barium, but by standing, or on the addition of a little liquor of ammonia, a white earthy precipitate, accompanied with the evolution of carbonic acid gas. A saturated solution of this salt, evaporated by a very gentle heat, or refrigerated, gives small prismatic crystals having neither smell nor taste.

_Uses, &c._ Similar to those of the other carbonates.--_Dose_, 6 or 7 to 20 or 25 gr.

=Ammonium, Chloride of.= NH_{4}Cl. _Syn._ MURIATE OF AMMONIA, SAL AMMONIAC, HYDROCHLORATE OF AMMONIA; CHLOROHYDRATE D'AMMONIAQUE, SEL AMMONIAC, &c., Fr.; SALMIAK, Ger. A substance which, as already noticed, appears to have been originally obtained, by sublimation, from the soot of camels' dung, in Egypt. In this country, at the present day, it is manufactured chiefly from the crude ammoniacal liquors obtained as secondary products in the manufacture of coal-gas and animal charcoal.

_Prep._ 1. From GAS-LIQUOR:--The crude ammoniacal liquor of the gas-works is, either at once, or after distillation,[48] neutralised with hydrochloric or sulphuric acid, the choice being given to the one which is the cheaper and more accessible at the place where the works are situated.

When hydrochloric acid is employed, the SATURATION is usually effected by allowing the acid to flow from a large wooden vessel or tank lined with lead or gutta percha into a large underground reservoir or tank containing the ammoniacal liquor, and having an exit-tube pa.s.sing into the chimney or shaft of the steam-engine, to carry off the sulphuretted hydrogen and other offensive gases liberated during the mixture. Sometimes the gas-liquor is acc.u.mulated in enormous covered wooden tuns, capable of holding from 10,000 to 20,000 gallons, or more; and the acid is added by raising the gutta-percha carboys containing it by means of cranes, and then thoroughly mixing it with the liquor by means of powerful 'agitators,' whilst the offensive fumes are either pa.s.sed off as before, or made to traverse the fire of the steam-engine before entering the chimney-shaft. The quant.i.ty of acid employed to effect saturation must, of course, depend on the ammoniacal strength of the gas-liquor operated on.

The usual proportions are 1-1/2 to 2 _lbs._ of the former, to each gal. of the latter; but in all cases sufficient should be added to impart a very faint acid reaction to the mixture. This last having been effected, the saline solution, now containing hydrochlorate of ammonia, is, after repose, ready to be pumped or run off into the evaporators.

[Footnote 48: This is now generally conducted in a large wrought-iron boiler, connected with a rude modification of Coffey's still; the object being to obtain the liquor freer from tar and more concentrated.]

The EVAPORATION of the crude saline solution is usually carried on in large square or rectangular cast-iron vats, of very moderate depth, and capable of holding from 1000 to 1500 gallons, or more. These are encased in brickwork, and are heated by a furnace, of which the flues pa.s.s in a sinuous course beneath the lining of brickwork on which the vats or pans rest. During the concentration of the liquid, the tar, &c., which separates and floats on the surface, and which thus seriously impedes evaporation, is, from time to time, removed by skimming. As soon as the sp. gr. reaches 125, any excess of acid in the solution is exactly neutralised with a little fresh ammoniacal liquor; by which any waste of acid is prevented, at the same time that any ferric salt present, and which would contaminate the ultimate product, is precipitated as sesquioxide. After settling for a short time, the hot liquor is ready to be transferred to the crystallisers.

The vessels employed in the CRYSTALLISATION are pans or tubs, usually circular and about 7 or 8 feet wide, by 2-1/2 to 3 feet deep; and are generally set on the ground, or are embedded either partially or wholly in it. The saline liquor being pumped or run into them at a little below the boiling temperature, crystallises as it cools; the only interference being occasional stirring or agitation, to prevent the formation of large crystals, which would be inconvenient in the subsequent part of the process. The time occupied in the crystallisation varies, according to the size of the 'crystallisers,' and the weather, from 3 or 4 to 8 or even 10 days. The 'mother-liquor' of the 'crystallisers' is pumped back into the evaporating pans for further concentration. The crude blackish salt (hydrochlorate) thus obtained is contaminated with tarry and oleaginous matter, free acid, water, &c.; from part of which it is freed by exposing it in a layer about 4 inches deep, on a cast-iron plate gently heated by a zigzag flue of a small furnace, until all the water is expelled; care being taken that the heat never rises high enough to volatilise the salt.

This operation is generally performed under a dome, or the expanded throat of a large chimney. The salt will now have become of a greyish-white colour, and is ready for the next operation.