3. Zinc, 2 _oz._; mercury, 5 _oz._

_Use._ To cover the cushions of electrical machines. A little of the

powder is poured on a piece of paper, crushed smooth with a flat knife,

and then spread thinly on the surface of the cushion or rubber, previously

slightly smeared with tallow; or the powder may be rubbed down with a

little tallow, prior to the application of it.

=Amalgam, Gild'ing.= _Syn._ AMALGAM OF GOLD.

_Prep._ Take of grain-gold, 1 part; mercury, 8 parts; put them into a

small iron saucepan, or ladle, and apply a gentle heat, using a smooth

piece of iron as a stirrer; when the solution or combination is complete,

pour it out on a clean plate or smooth stone slab.

_Use._ To gild brass, copper, &c., in the common process of wash or

fire-gilding. A less proportion of gold than the above is used when a thin

and cheap gilding is required; as by increasing the quantity of the

mercury the same weight of the precious metal may be extended over a much

larger surface.

=Amalgam, Sil'vering.=--_a._ For METALS. _Syn._ AMALGAM OF SILVER.

_Prep._, _Uses_, &c. As the last, but substituting silver for gold.

_b._ For GLASS. _Prep._ 1. Lead, tin, and bismuth, of each, 1 _oz._; bees'

wax or resin 1/4 _oz._; melt, skim off the dross, cool to the lowest point

at which the mixture will remain liquid, and add of quicksilver 10 _oz._;

mix well with an iron rod.

2. Lead and tin, of each, 1 _oz._; bismuth, 2 _oz._; quicksilver, 4 _oz._;

as the last.

_Uses, &c._ For silvering the insides of hollow glass vessels, globes,

convex mirrors, &c. The glass being thoroughly cleaned and dried, is

carefully warmed, and the amalgam, rendered fluid by a gentle heat, is

poured in, and the vessel turned round and round, so as to bring the metal

into contact with every part which it is desired to cover. At a certain

temperature it will be found to readily adhere to the glass. The excess is

then poured out, and the vessel set aside to cool.

=Amalgams, Tooth.= See DENTISTRY and TOOTH-CEMENTS.

=Amalgam, Var'nisher's.= _Prep._ Melt grain-tin, 4 _oz._, with bismuth, 1

_oz._; add quicksilver, 1 _oz._, and stir till cold; then grind it very

fine with white-of-egg or with varnish, and apply the mixture to the

figure or surface with a soft brush. It is used in several of the

ornamental trades.

=Amalgamating Salts.= Boil a solution of pernitrate of mercury with excess

of equal parts of powdered persulphate and perchloride of mercury, and

decant the liquid portion of the result for use. Chiefly used for

amalgamating the zinc plates of galvanic batteries, also as a substitute

for mercury in gilding by the amalgam process.

=AMAL'GAMATED.= _Syn._ AMALGAMA'TUS, L.; AMALGAMÉ, Fr. Compounded or

blended with quicksilver; formed into an amalgam.

=AMALGAMA'TION.= [Eng., Fr.] _Syn._ AMALGAMA'TIO, L.; VERQUICKEN, Ger. The

act or process by which an amalgam is formed; hence loosely, the mixing or

blending of different things. In the art of the refiner, the operation of

separating gold and silver from their ores by means of mercury.

=AM'ANDINE= (-d[=e]ne). _Prep._ 1. (Transparent.)--_a._ Fine new white or

pale honey, 4 _oz._; white soft-soap (prepared from lard and potassa), 2

_oz._; mix thoroughly in a marble mortar, adding 1 or 2 teaspoonfuls (if

necessary) of solution of potassa, until a perfectly homogeneous paste or

cream is produced; then rub in, by degrees, and very gradually, of oil of

almonds, 7 _lbs._ (or q. s.), previously mixed with essential oil of

almonds, 1 _oz._; essence (oil) of bergamot, 3/4 _oz._; oil of cloves, 1/2

_oz._; and balsam of Peru, 3 _dr._ The product, which should have a rich,

transparent, jelly-like appearance and behaviour, is, lastly, put into

pots for use or sale.

_b._ (G. W. S. Piesse.) Simple syrup, 4 oz.; white soft-soap (see

_above_), 1 oz.; oil of almonds, 7 _lbs._ (previously scented with--);

essential oil of almonds and bergamot, of each 1 _oz._; oil of cloves, 1/2

_oz._; the whole being mixed, &c., as before. Both the above are of very

fine quality. Glycerin, in the proportion of about 1/2 _oz._ to each _lb._

of the products, added with the soap, improves their softening quality.

2. (Opaque.)--_a._ From white potash-soap and gum-mucilage (thick), of

each 3 _oz._; new white honey, 6 _oz._; and the yelks of 5 large eggs;

well mixed together, and afterwards intimately blended first, with oil of

almonds (scented as before, or at will), 2 _lbs._; and afterwards, with

thick pistachio-milk (made of the fresh-peeled nuts and rose-water), 5

_fl. oz._

_b._ From almond-paste, honey, white potash-soap, and glycerin, of each. 1

_oz._; yelk of 1 egg; oil of almonds, 1/2 pint (holding in solution--);

essential oil of almonds, 1 _dr._; balsam of Peru, 1/2 _dr._

_Uses, &c._ To whiten and soften the skin, and to prevent it chapping. A

small portion, about half the size of a filbert, with a few drops of warm

water, produces a very white and rich lather, with which the hands and

face are lightly rubbed, and the skin, in a short time, gently wiped with

a small napkin, whilst the water on it is still milky.

The manufacture of AMANDINE is a matter of some difficulty and labour. The

details essential to success are given under EMULSINES. It is sometimes

coloured, which is done by infusing or dissolving in the oil, before using

it, a little--spinach-leaves, for GREEN; and palm-oil, or annatto, for

YELLOW and ORANGE. A beautiful SCARLET or CRIMSON tinge may be given to it

by a little liquid rouge or carmine (ammoniacal), added just before

removing it from the mortar. See EMULSINES, OLIVINE, PASTE, &c.

=AMANI'TA MUSCA''RIA.= The fly-agaric or fly-mushroom. See AGARIC.

=AMANITINE.= _Syn._ AMANITINA, L. The name given by Letellier to the

poisonous principle of _amani'ta muscaria_, and some other species of

fungi. It is brown, uncrystallisable, and soluble.

=AMARA.= [L.] In _medicine_ and _pharmacology_, the bitter tonics.

=AMARANTH.= _Syn._ AMARANTH'US, L.; AMARANTE, Fr. The flower

love-lies-bleeding (_amaranthus caudatus_--Linn.). In _poetry_, an

imaginary flower that never fades. (Milton.) In _chromatics_, a colour

inclining to purple.

=AMARYTH'RINE.= A bitter principle found, in certain lichens, associated

with erythrine (which _see_).

=AMASI.= This, the native name given by the natives of Central Africa to

sour milk, which they prepare by adding to the new milk, a small quantity

of milk previously allowed to become sour. The milk thus acidified is

considered by them far more wholesome than new milk.

=AMAUROSIS.= _Syn._ GUTTA SERENA, SUFFUSIO NIGRA. A diminution or total

loss of sight, arising from paralysis of the retina or optic nerve.

=AM'BER.= _Syn._ ELEC'TRON, Gr.; ELEC'TRUM, SUC'CINUM (Ph. D.), L.; AMBRE,

SUCCIN, Fr.; BERNSTEIN, Ger.; LYNX-STONE[dagger], LA'PIS LYN'CIS[dagger],

L. A well-known yellowish, semi-transparent, fossil resin, of which

trinkets and the mouth-pieces of pipes are commonly made.

_Nat. hist., &c._ Amber is found in detached pieces on the sea-coast, and

is dug up in diluvial soils. That of commerce comes chiefly from the

southern coasts of the Baltic, where it is cast ashore between Königsberg

and Memel; and from Ducal Prussia, Saxony, Poland, Sicily, and Maryland

(U.S.), where it is dug out of beds or mines. It has also been found on

the shores of Norfolk, and small pieces are occasionally dug up in the

gravel pits round London. It is probably an antediluvian resin; and when

found on the coast, is supposed to be disengaged, by the action of the

sea, from neighbouring beds of lignite or fossil coal. Much diversity of

opinion for a long time prevailed amongst naturalists and chemists as to

the origin of amber, some referring it to the vegetable, others to the

mineral, and some even to the animal kingdom; its natural history and

analysis affording something in favour of each. The vegetable origin of

amber has, however, been recently shown by various facts, and is now

generally admitted. According to Sir David Brewster, its optical

properties are those of an indurated vegetable juice. ('Ed. Phil. Journ.,'

ii.) Insects and fragments of vegetables are frequently found imbedded in

it; and this in a manner which could only have occurred when the resin was

a viscid fluid. Microscopical researches have led to the conclusion that

it is the production of some species of pine, closely allied to the pinus

balsamea. ('Entom. Trans.,' i & ii.)

_Manuf._ Amber is WORKED in a lathe, POLISHED with whiting and water or

rottenstone-and-oil, and FINISHED OFF by friction with flannel. During the

operation the pieces often become hot and electrical, and fly into

fragments; to avoid which they are kept as cool as possible, and only

worked for a short period at a time. The workmen are said to often suffer

considerably from electrical excitement. Amber is JOINED and MENDED by

smearing the surface of the pieces with linseed or boiled oil, and then

strongly pressing them together, at the same time holding them over a

charcoal fire, or heating them in any other convenient way in which they

will not be exposed to injury. The commoner varieties are HARDENED and

rendered CLEARER, either by boiling them in rape oil for about 24 hours,

or by surrounding the pieces with clean sand in an iron pot, and exposing

them to a gradually increasing heat for 30 or 40 hours. During this

process small fragments are kept in the sand at the side of the pot, for

the purpose of occasional examination, lest the heat be raised too high,

or be too long continued.

_Prop., &c._ Hard; brittle; tasteless; glossy; generally translucent, but

sometimes opaque, and occasionally, though rarely, transparent; colour

generally yellow or orange, but sometimes yellowish-white; becomes

negatively electric by friction; smells agreeably when rubbed or heated;

fracture conchoidal and vitreous or resinous; soluble in the pure

alkalies, and, without decomposition, in oil of vitriol, which then

becomes purple; insoluble in the essential and fixed oils without long

digestion and heat; soluble in chloroform; melts at about 550° Fahr.;

burns with a yellow flame, emitting at the same time a peculiar fragrant

odour, and leaving a light and shiny coal. By dry distillation it yields

inflammable gases, a small quantity of water, a little acetic acid, a

volatile oil (OIL OF AMBER; O'LEUM SUC'CINI, L.) at first pale, afterwards

brown, thick, and empyreumatic, and an acid (SUCCIN'IC ACID; ACIDUM

SUCCIN'ICUM, L.); with residual charcoal 12 to 13%. Sp. gr. 1·065 to 1·09,

but usually about 1·070. It cannot be fused without undergoing more or

less chemical change.

_Ident._ Amber may be known from mellite and copal, both of which articles

are occasionally substituted for it, by the following characteristics:--1.

MELLITE is infusible by heat, and burns white:--2. A piece of COPAL,

heated on the point of a knife, catches fire, and runs into drops, which

flatten as they fall:--3. AMBER burns with spitting and frothing, and when

its liquefied particles drop, they rebound from the plane on which they

fall (M. Haüy):--4. Neither mellite nor copal yields succinic acid by

distillation; nor the agreeable odour of amber when burnt; nor do they

become so readily electric by friction.

_Uses._ It is chiefly made into mouth-pieces for pipes, beads for

necklaces, and other ornaments and trinkets. It is also used as the basis

of several excellent varnishes. In _medicine_, it was formerly given in

chronic coughs, hysteria, &c.--_Dose_ (of the powder), 10 to 60 gr.

_Remarks._ The finer sorts of amber fetch very high prices. A piece 1

_lb._ in weight is said to be worth from 10£ to 15£. 5000 dollars a few

years since were offered in Prussia for a piece weighing 13 _lbs._, and

which, it was stated by the Armenian merchants, would fetch from 30,000 to

40,000 dollars in Constantinople. It is more valued in the East than in

England; and chiefly on account of the Turks and other Orientals believing

it to be incapable of transmitting infection. In the royal cabinet,

Berlin, there is a piece weighing 18 _lbs._, supposed to be the largest

ever found. The coarser kinds alone are employed in medicine, chemistry,

&c.

=Amber, Ac'id of=* ([)a]s'-). Succinic acid.

=Amber, Bal'sam of.= _Syn._ BAL'SAMUM SUC'CINI, L. The thick matter left

in the retort after the rectification of oil of amber; and which it

resembles in its properties.

=Amber, Facti''tious= (-t[)i]sh'-). _Syn._ SUC'CINUM FACTI''TIUM, L.

Mellite, copal, and anime, have each been substituted for amber,

especially for small fragments of it. Recently an imitation has been

produced by acting on gutta percha with sulphur, at a high temperature,

which, either alone or in combination with copal, is said to have been

extensively passed off for genuine amber.

=Amber, Liq'uid=[dagger]. See LIQUID-AMBAR.

=Amber, Oil of.= See OILS.

=Amber, Re'sin of.= See PYRÉTINE.

=Amber, Salt of.= Succinic Acid.

=Amber, Sol'uble.= _Prep._ Fragments of amber are cautiously heated in an

iron pot, and as soon as it becomes semi-liquid, an equal weight of pale

boiled linseed-oil, previously made hot, is very gradually stirred in, and

the whole thoroughly blended. Used as a cement for glass and earthenware,

and thinned with oil of turpentine to make varnishes. It will keep any

length of time if preserved from the air.

=AMBER-CAM'PHOR.= See PYRÉTINE (Crystalline).

=AM'BER DRINK=[dagger]. Amber-coloured malt liquor.

=AM'BER-SEED.= Musk-seed (which _see_).

=AM'BER-TREE.= The popular name of a species of anthospermum, an evergreen

shrub, of which the leaves, when bruised, emit an agreeable odour.

=AM'BERGRIS= (-gr[)i]s; gr[=e]se[double-dagger]). _Syn._ GREY AMBER*;

AMBRAGRI''SEA (gr[)i]zh'-e-[)a]), L.; AMBREGRIS, Fr.; AMBRA, AMBAR, Ger.

An odorous, solid substance, found floating on the sea in tropical

climates, and in the cæcum of the cachalot or spermaceti whale (physeter

macrocephalus). It has been supposed by some to be a morbid secretion of

the liver or intestines, analogous to biliary calculi; but according to Mr

Beale, it consists of the mere indurated fæces of the animal, perhaps (as

suggested by Brande and Pereira) somewhat altered by disease. "Some of the

semifluid fæces, dried with the proper precautions, had all the properties

of ambergris." (Beale.) It is occasionally found in masses weighing from

60 to 225 _lbs._

_Prop., &c._ Solid, opaque, ash-coloured, streaked or variegated, fatty,

inflammable; remarkably light; highly odorous,[40] particularly when

warmed, cut, or handled--the odour being peculiar and not easily described

or imitated, of a very diffusive and penetrating character, and

perceptible in minute quantities; rugged on the surface; does not

effervesce with acids; melts at 140° to 150° Fahr. into a yellowish

resin-like mass; at 212° flies off as a white vapour; very soluble in

alcohol, ether, and the volatile and fixed oils. It appears to be a

non-saponifiable fat, analogous to cholesterine. Sp. gr. 0·780 to

0·926.[41]

[Footnote 40: It has a "pleasant musk-like odour, which is supposed to be

derived from the squid ('sepia moschata') on which the animal feeds," the

"horny beaks" of which "are often found imbedded in the masses."

(Pereira.) It has a smell resembling that of dried cow-dung." (Redwood,

'Gray's Supplement,' 1857, p. 606.)]

[Footnote 41: Sp. gr ·780 to ·896--Brande; ·908 to ·920--Pereira.]

_Pur._ From the high price of genuine ambergris it is very frequently, if

not nearly always, adulterated. When quite pure and of the best quality,

it is--1. Nearly wholly soluble in hot alcohol and ether, and yields about

85% of ambreine:--2. It almost wholly volatilises at a moderate heat, and

when burnt leaves no notable quantity of ashes; a little of it exposed in

a silver spoon melts without bubble or scum; and on the heated point of a

knife it is rapidly and entirely dissipated:--3. It is easily punctured

with a heated needle, and on withdrawing it, not only should the odour be

immediately evolved, but the needle should come out clean, without

anything adhering to it (Normandy):--4. The Chinese are said to try its

genuineness by scraping it fine upon the top of boiling tea. "It should

dissolve (melt) and diffuse itself generally." Black or white is bad. The

smooth and uniform is generally factitious.[42]

[Footnote 42: Ure's 'Dict. of A., M. & M.,' 5th Ed., i, 128.]

_Uses, &c._ It is highly prized for its odour, which is found greatly to

improve and exalt that of other substances; hence its extensive use in

perfumery. In _medicine_ it was formerly given as an aphrodisiac, in doses

of 3 to 10 gr. "A grain or two, when rubbed down with sugar, and added to

a hogshead of claret, is very perceptible in the wine, and gives it a

flavour, by some considered as an improvement." (Brande.)

=Ambergris Facti''tious.= An article of this kind, met with in the shops,

is thus made:--Orris-powder, spermaceti, and gum-benzoin, of each, 1

_lb._; asphaltum, 3 or 4 _oz._; ambergris, 6 _oz._; grain-musk, 3 _dr._;

oil of cloves, 1 _dr._; oil of rhodium, 1/2 _dr._; liquor of ammonia, 1

_fl. oz._; beaten to a smooth hard mass with mucilage, and made into lumps

whilst soft. This fraud is readily detected.

=AM'BREINE= (-bre-[)i]n). _Syn._ AMBREI'NA, L.; AMBREINE, Fr.; AMBARSTOFF,

Ger. The fatty, odorous principle of ambergris.

_Prep._ Digest ambergris in hot alcohol (sp. gr. 0·827) until the latter

will dissolve no more, then filter. The AMBREINE will be deposited as the

solution cools, in an irregular crystalline mass, which may be purified by

recrystallisation in alcohol.

_Prop., &c._ Melts at about 90°; volatilises at 212° to 220° Fahr.; nitric

acid converts it into AMBREIC ACID. It closely resembles

cholesterine.--_Prod._ 85%.

=AMBRETTE'= (-br[)e]t'). [Fr.] Musk-seed.

=AMBROSIA, RING'S VEGETABLE= (Tubbs, Peterborg, U.S.). A liquid with a

sediment, containing 1 per cent. of lead. (Chandler.)

=AMEISEN BALSAM.= Von Dr Livingstone (Ahnelt, Charlottenburg). Balsam of

ants. Castor oil, 72 grms.; balsam of Peru, 2 grms.; bergamot, 5 drops.

(Hager.)

=AMERICAN PILLS= (A. H. Boldt, Lexington). For full-blooded, corpulent

persons, and for those of sedentary habits, for irregular menstruation,

and against contagious diseases. Made of scammony, rhubarb, and soap.

(Schädler.)

=AMERICAN MEDICINES, Dr SAMPSON'S= (New York). Two kinds of pills of

coca:--No. 1. 85 pills composed of coca extract and coca powder, and each

pill containing about 0·006 grm. of a morphia salt. No. 2. 50 pills, also

of coca, and each containing 0·05 grm. of powdered iron. Both kinds are

rolled in lycopodium. (Hager.)

=AMERICAN PILLS FOR ASTHMA.= Gilded pills made of gum ammoniacum.

=AMERICAN SCHAMPOO-FLUID FOR PROMOTING THE GROWTH OF THE HAIR.= Spirit of

wine and rum, with some carbonate of ammonia and potash.

=AMERICAN DROPS FOR TOOTHACHE= (Majewsky, Warsaw) have been found of

various composition. Some which profess to have taken a prize at the

Vienna Exhibition were composed of French brandy, containing common salt,

and coloured with cochineal. The first was a spirituous solution of an

ethereal oil with some oil of cloves, coloured rather reddish; No. 2 was a

similar solution with some oil of peppermint and tincture of rhatany; and

No. 3 was merely a diluted solution of No. 2. (Hager.)

=AMERICAN UNIVERSAL BLOOD-PURIFYING HERB TEA= (Dr Kuhr), for women's

diseases, hysteria, nervous debility, epilepsy, stomachic complaints,

asthma, hæmorrhoids, gout, rheumatism, worms, and much besides. White

horehound, marsh mallow, liquorice wood, and sassafras, of each, 10 parts;

anise, coriander and fennel, of each, 5 parts; red poppy petals, 4 parts;

lavender flowers, 2 parts; senna, peppermint, millefoil flowers, and

valerian root, of each, 1 part. (Kuhr and Selle.)

=AM'ETHYST= (-th[)i]st). _Syn._ PURPLE ROCK-CRYSTAL; AMÉTHYSTE, Fr.;

AMETHYS'TUS, L. A beautiful sub-species of quartz or rock crystal, of a

violet-blue colour of varying intensity, in great request for cutting into

seals, brooches, and other like articles of ornament. It was known and

prized in the earliest ages of antiquity. Among the ancients, cups and

vases were made out of this mineral; and it was an opinion of the Greeks

and Persians, that an amethyst bound on the navel would counteract the

effects of wine, and that wine drank out of an amethystine vessel would

not intoxicate. See GEMS.

=Amethyst.= In _chromation_, _dyeing_, &c., a rich variety of deep violet

colour. Hence, AMETHYST'INE ([)i]n), &c.

=Amethyst, Orient'al.= A rich violet-blue variety of transparent,

crystallised corundum.

=AM'IANTH= (-e-[)a]nth). _Syn._ AMIANTH'US, AMIAN'TUS, L.; AMIANTE, Fr.

The whiter and more delicate varieties of asbestos, particularly those

which possess a satiny lustre.

=AM'IDIN= (-e-d[)i]n). [Eng., Fr.] _Syn._ AM'YDINE; AMIDI'NA, L. A

substance noticed by Saussure in starch-paste, when long kept. According

to Caventou, it is formed at once by the action of boiling water on

starch. It forms the interior substance of the starch-grains, and its

properties are intermediate between those of starch and gum. It is,

indeed, the soluble part of starch, of which a perfect solution can only

be obtained by prolonged ebullition in a large quantity of water.

=AMID'OGEN.= NH_{2}. Literally, the generator of amides; in _chemistry_,

the name given by Kane to an hypothetical body, composed of two atoms of

hydrogen and one of nitrogen. It forms AMIDES by combining with other

bodies.

=Amidogen Ba'ses.= In _chemistry_, 'amines' in which only one equiv. of

hydrogen is replaced by an organic radical; and hence called PRIMARY

MON'AMINES.

=AMMONIA.= NH_{3}. _Syn._ AMMONIA GAS, AMMONIACAL GAS, ANHYDROUS AMMONIA,

TERHYDRIDE OF NITROGEN; AMMONIAQUE, Fr.; AMMONIAK, Ger. At the present day

the ammonia of commerce is chiefly prepared from the ammoniacal liquor of

the gas-works and the manufactories of ivory black, animal charcoal, &c.

Lant or stale urine is also an important source of ammonia. In these

places a large quantity of crude ammoniacal liquor is produced; to which

either sulphuric or hydrochloric acid is added, by which it is converted

into a salt, which may be obtained nearly pure by evaporation, and one or

more crystallisations, and, in the case of the hydrochlorate and

carbonate, subsequent sublimation. Other sources and processes have been

sought out and occasionally adopted for the preparation of the principal

salts of ammonia (its sulphate, carbonate, and hydrochlorate); some of

which have been patented, but few of them have got into general use, or

have been carried out on the large scale. For many years the manufacture

of ammonia and its compounds has incessantly engaged the attention of

European chemists.

Many unsuccessful attempts have been made to directly convert the nitrogen

of the atmosphere into ammonia. Of these we may mention one which

consisted in passing a mixture of nitrogen, carbonic oxide and steam over

red-hot hydrate of lime, whereby ammonia and carbonic acid are formed. A

plan for the indirect application of atmospheric nitrogen in the

preparation of ammonia was suggested by Margueritte, in which it was

proposed that cyanide of barium should be prepared, and its nitrogen

converted into ammonia by the aid of a current of superheated steam at

600° C. According to the description of this process in a patent, not,

however, in practice, native carbonate of baryta is calcined with about

30% of coal-tar, for the purpose of rendering the mass porous as well as

more readily converted into caustic baryta at a lower temperature. The

carbonaceous mass is, after cooling, placed in a retort, and kept at a

temperature of 300° C., while air and aqueous vapour are forced in, the

result being the formation of ammonia in considerable quantity, and

carbonate of baryta, which is again used.

Ammonia is evolved from ball soda while cooling; during the formation of

cyanogen and cyanide of potassium in blast furnaces; and the formation of

sal-ammoniac in the process of iron smelting.

Ammonia, in a state of combination, is found, in variable quantities,

among the saline product of volcanoes, in sea and rain water, in

bituminous coal, in urine, in guano, and in the atmosphere, especially

that of large towns. The minute stellated crystals sometimes found on

dirty windows in London, and other populous cities, consist of sulphate of

ammonia. It is also found in clayey and peaty soils, and in minute

quantity in good air and water. (Brande; Fownes; Letheby.) In the free

state it exists in the juices of some plants, and in the living blood of

animals, and it is freely developed during the decomposition of azotised

vegetable substances, and during the putrefaction of animal matter.

[Illustration]

_Prep._ A mixture of fresh hydrate of lime with an equal weight of sal

ammoniac (both dry and in fine powder) is introduced into a glass flask or

retort, the beak of which communicates with one end of a U-shaped tube

filled with small fragments of recently burnt quick-lime, and from which

extends another glass tube, about 18 inches long, having its further end

bent up ready to be placed under a gas-jar, on the shelf of a mercurial

pneumatic trough. (See _engr._) The joints being all made air-tight by

collars of india rubber, heat is applied by means of a spirit-lamp, and as

soon as the air contained in the apparatus is expelled, the gas is

collected for use. It cannot be dried by means of chloride of calcium.

Powdered quick-lime may be substituted for the hydrate in the above

process; in which case the evolved gas is anhydrous, but a much greater

heat is then required for its liberation.

_Comp._ Ammonia is a compound of 3 volumes of hydrogen, and 1 vol. of

nitrogen, condensed into two volumes; and by weight of 82·35 parts of

nitrogen, 17·65 parts of hydrogen, or, in other words, of one atomic

weight of nitrogen and three of hydrogen, having the formula NH_{3}.

_Prop._ Gaseous, colourless, invisible; highly pungent, acrid, irritating

and alkaline; irrespirable, unless very largely diluted with air;

extinguishes combustion; burns slowly in oxygen; sp. gr. 0·589; 100 cub.

inches weigh 18·26 gr. Under a pressure of 6·5 atmospheres, at 50° Fahr.,

it forms a transparent, colourless liquid of the sp. gr. 0·731; at 60°

Fahr. this liquid expanded into 1009 times its volume of ammoniacal gas;

at -40° Fahr., and the ordinary atmospheric pressure, it forms a subtle

colourless liquid, which at -103° Fahr. freezes into a white, translucent,

crystalline substance. (Faraday.) It is highly basic; all its salts are

either volatilised or decomposed at, or under, a red heat--those with a

volatile acid sublime unchanged--those with a fixed acid lose their

ammonia. It is decomposed into its elements by transmission through a

red-hot tube; and when in contact with metallic oxides or spongy platinum,

at the same temperature, the newly evolved hydrogen unites with the oxygen

of the oxide or of the atmosphere, forming water. Water at 50° Fahr.

absorbs 670 times its volume of this gas, and the solution has the sp. gr.

0·875. Its concentrated aqueous solution boils at 130°, and freezes at

-40° Fahr.

_Tests, &c._ Ammonia is recognised by--1. Its pungent odour:--2. By

turning vegetable blues green, and vegetable yellows brown; but which soon

regain their previous colours, especially on the application of heat:--3.

By producing dense white fumes when brought in contact with those of

hydrochloric acid:--4. By the Nessler test (see WATER, QUANTITATIVE AND

QUALITATIVE ANALYSIS OF):--5. If a saturated solution of arsenious acid is

mixed with a solution of nitrate of silver (strength 2%) a trace of

ammonia causes the formation of try-argentic arsenite:--6. Böttger says a

very delicate test for ammonia is afforded by an aqueous solution of

carbolic acid. On adding to a liquid containing the smallest quantity of

ammonia, or an ammoniacal salt, a few drops of this solution, and then a

small quantity of a filtered solution of chloride of lime, the liquid

becomes green, especially when warmed.

_Phys. eff., &c._ Inhaled, undiluted with air, it is an irritant poison,

producing spasms of the glottis, convulsions, and death; even when diluted

it acts as a powerful acrid, and local irritant; applied to the skin it

causes vesication. The use of the pungent odour of common 'smelling

salts,' in syncope, headache, &c., is well known. Largely diluted with

air, it has been recently highly extolled in chronic hoarseness, asthma,

&c.; and as an antidote to the fumes of bromine, chlorine, and hydrocyanic

acid. (Smee.)

_Ant., &c._ The vapour of acetic acid or common vinegar, freely inhaled.

It may be produced by sprinkling a little on a piece of hot iron, as a

heated shovel. If bronchial inflammation follows, it must be treated by

purgatives and a low diet; and, if severe, and the patient be plethoric or

robust, by venesection or cupping.

_Uses._ Ammonia is employed in numerous processes in _chemistry_ and the

_arts_; but chiefly in the form of 'liquor of ammonia,' 'spirits of

hartshorn,' &c., and in combination, under the form of salts. In its pure

or gaseous state it possesses little practical interest.

=Ammonia, Solution of.= _Syn._ SOLUTION OF AMMONIA, LIQUOR AMMONIÆ,

AMMONIUM HYDRATE, AMMONIA, Eng.; AMMONIAQUE LIQUIDE, DISSOLUTION

D'AMMONIAQUE, ESPRIT DE SAL AMMONIAC, Fr.; ATZENDER AMMONIUM-LIQUOR,

SALMIAK-GEIST, Ger.; LIQUORE DI AMMONIACO, Ital. Ammonia gas readily

dissolves in water, one volume of water absorbing about 670 volumes of

ammonia, much heat being liberated, and the solution increases greatly in

volume.

This solution is regarded in two very different lights; firstly and most

generally as simply a solution of gaseous ammonia, a view rendered most

probable by its general physical and by many chemical reactions; by a few,

however, it is looked upon as a solution of ammonium hydrate.

[Illustration]

Prepared by distilling, in a tubular retort, equal parts of sal ammoniac,

hydrated lime, or slaked lime and water, and passing the gas evolved

through a set of Wolff's bottles partially filled with water, as in the

figure above.

[Illustration:

_A_, Cylindrical Iron Retort.

_B_, Furnace for ditto.

_C C C C_, Stoneware Receivers.

_D D D D_, Connecting Pipes.

_E F_, Waste Pipe and Receiver.

_G_, Safety Tube. ]

Commercially this article is prepared on the large scale, from a mixture

of about equal parts of fresh-slaked lime and sal-ammoniac or sulphate of

ammonia, which is heated in an iron cylinder or retort connected with a

set of 'refrigerators,' the latter consisting of a row of stoneware

bottles with double necks, containing water, and kept very cold. The

general arrangement of the apparatus used in this manufacture is exhibited

above, and with the accompanying references, will be easily understood.

The 'condensers,' when in use, are surrounded with cloths (not shown in

the _engr._) kept wet with very cold water, whilst constant current of

cold air is commonly made to pass over them. The pipe (_D_) leading from

the retort is also several feet long, and is advantageously passed through

a wooden screen in order that the radiated heat of the retort and

brickwork of the furnace may be intercepted as much as possible.

Two different methods of proceeding are adopted in this process. In the

one the dry pulverulent ingredients are mixed together, and the resulting

gas distilled over into the water placed in the receivers. In the other

the lime is made into a 'pap' with water, and the ammonia-salt, in coarse

powder, being added, the whole is rapidly blended together, before closing

the retort, and applying heat. In either case a proportionate quantity of

water is put into the condensers, and the operation is nearly similar; but

the latter method requires the least heat, and so far as the receivers and

refrigerators are concerned, is, perhaps, the one most easily managed. It

is that which is always, and necessarily followed, when sulphate of

ammonia is employed.

_Prop., Uses, &c._ Highly pungent, caustic, and alkaline; lighter than

water, and presenting in a liquid form most of the characteristics of pure

ammonia. When strongest has a sp. gr. of ·875, and contains about 39 per

cent. of ammonia, but the usual strong ammonia of commerce has a sp. gr.

of but ·88. The liquor ammonia fortior, B. P., has a sp. gr. of about

·893, and contains 32·5 per cent. of ammonia, while the liquor ammoniæ B.

P. has a sp. gr. of about ·940, and contains about 10 per cent. of

ammonia. As a medicine it is antacid, diaphoretic, rubefacient, stimulant,

and counter-irritant; and is used in various affections in which these

remedies are indicated. As a vesicant it is superior to cantharides, and

as a caustic it is used with advantage in the bites of rabid animals,

especially those of serpents and insects. Its vapour is a common nasal

stimulant in faintings, epilepsy, &c. In its concentrated form it is a

corrosive poison.--_Dose_, 5 to 25 drops, in cold water, or milk and

water. It enters into the composition of several valuable external

remedies, and is in constant employment in the _chemical laboratory_, both

as a reagent and for the preparation of other compounds.

_Ant., &c._ When the fumes have been inhaled, the patient should be

exposed to a current of fresh air; and when the liquid has been swallowed,

vinegar or lemon-juice mixed with water may be administered; followed by

an emetic, or, on its failure, by the stomach-pump.

_Estim._ The quantity of gaseous ammonia in pure water of ammonia is

easily determined from the specific gravity of the liquid, or from its

saturating power. When impure or mixed with other substances, a given

weight of the sample is placed in a small retort, the end of which is made

to dip into a vessel containing dilute hydrochloric acid. A strong

solution of caustic potassa is then poured into the retort, and heat

applied by means of a small spirit lamp. When _all_ the ammonia is

distilled over, the acid solution is evaporated to dryness, by the heat of

a water bath, and the residuum (chloride of ammonium) weighed. Each grain

of the chloride thus found represents ·31804 gr. of pure ammonia; 53·5

parts of the former being equivalent to 17 of the latter. If the article

for examination be a solid substance (as a salt), it may be dissolved in

water, or in dilute acid, before being put into the retort.

In accurate experiments in the laboratory, ammonia is usually WEIGHED

either as chloride of ammonium (see _above_), or as ammonio-bichloride of

platinum (NH_{4}Cl, PtCl_{2}); every gr. of the latter representing ·07614

gr. of pure ammonia. Sometimes, though rarely, the quantity of ammonia is

determined from the volume of nitrogen eliminated from it, of which 14 gr.

represent 17 gr. of ammonia.

_Concluding remarks, Patents, &c._ Whatever form or process may be adopted

for the preparation of liquid ammonia, it is absolutely necessary to keep

the receivers as cool as possible, by means of snow, ice, or a current of

very cold water, for the purpose of promoting the absorption of the gas,

and to prevent its loss. On the small scale, the glass receivers or

bottles may be most conveniently surrounded with ice, or a freezing

mixture, and two, or more of them, should be furnished with safety-tubes,

to prevent accidents. On the large scale, a capacious oblong retort,

usually of iron (but sometimes, though seldom, of lead), with a large

opening or tubulature conveniently situated for inserting the 'charges,'

and withdrawing the residuum of the distillation, is employed. The

tubulature, or opening, is closed by means of a large and accurately

ground iron stopper, or with a door secured by screws, as the case might

be. The stopper is well greased before insertion, and is removed by means

of a powerful lever. Should it become so firmly fixed that it cannot be

displaced in the usual manner, a cloth moistened with cold water, and

carefully wrapped round it, without touching the neck of the retort, will

generally cause it to contract sufficiently to enable the operator to

remove it with facility. Sometimes a large iron kettle, with a moveable

and accurately fitting lid secured in its place like that of a 'Papin's

digester,' and having a large and long tubulature in its centre, is

employed instead of a retort, over which it has the advantage of exposing

a larger opening for the removal of the residuum of the process. In either

case the distillatory vessel is imbedded in sand supported by fire-brick,

and is not exposed directly to the heat of the furnace. Before commencing

the distillation the joints are all well luted, to avoid leakage. An

excellent plan is to pass the gas, as it leaves the retort, through a

silver or pewter 'worm' or 'refrigerator' set in a tub supplied with a

stream of very cold water; by which it will be sufficiently cooled before

it reaches the 'receivers' to obviate the necessity of any further

attention to them than keeping the cloths wrapped round them constantly

moistened with cold water. The lower end of the 'worm' should be

connected, by means of a balloon-shaped 'adopter,' with the 'still,' and

the upper end with the first 'receiver,' the use of the balloon being to

intercept any volatilised ammonia-salt that might be accidentally driven

over by the heat being too high, or too suddenly raised.

The heat should be gradually applied, and very gradually raised, to

prevent any of the sal ammoniac or sulphate being volatilised

undecomposed; and even towards the end of the process it should not even

approach redness.

The lime is best 'slaked' and 'papped' with about 4 parts of water; as a

lower heat is then required to expel the gas, and it passes over more

easily and fully than when less water is employed. This is absolutely

necessary when the sulphate is the ammonia-salt used; as otherwise the

residuum of 'sulphate of lime' would become so hard that it could not be

easily removed from the retort.

The gas being wholly expelled from the retort, or other distillatory

vessel, it is disconnected from the receivers, and (when sal ammoniac has

been employed) the heat is raised sufficiently high to fuse the residual

chloride of calcium, which is then at once baled or poured out. Glass

retorts often suffer fracture at this point; but if they escape now, it

generally happens that they are broken when heat is applied for a second

operation. Hence, according to Prof. Muspratt, it is rare to find a

retort, even when carefully handled, that will stand two operations.

When crude sulphate of ammonia is employed it is advisable to have only a

little water in the first receiver, which is placed there merely to purify

the gas which passes through it, and to retain any traces of volatile

empyreumatic or oily matter which may be carried over with it.

Pure solution of ammonia is most easily obtained from 'sal ammoniac,' but

crystallised sulphate of ammonia, often crude, is more commonly employed,

on account of its lower price.

The preparation of pure solution of ammonia admits of no other

improvements than such as merely affect the form of the apparatus employed

to produce it; and hence, unlike the ammonia-salts of commerce, has been

little meddled with by inventors and patentees. Among the plans having for

their object the production of an ammoniacal solution, more or less

concentrated, fitted for many of the purposes of the arts, and for the

preparation of salts, but not for chemical and medical use, besides those

of Reece, Spence, Crane and Jullien, &c., already noticed, may be

mentioned--

1. That of Watson (Patent dated 1838) in which gas-liquor mixed with a

proper quantity of fresh-slaked lime is distilled from a spacious retort

or still into a receiver containing cold water, until much steam passes

over with the gas, when the strong alkaline liquor forming the distillate,

and called the first portion, is drawn off. The distillation is then

continued, when a weaker and impurer solution is obtained, called the

second portion. The first portion is then reintroduced into a retort or

still with a small quantity of fresh lime, and the distillation repeated.

The product the patentee calls the first portion of the second

distillation. The latter is a strong ammoniacal liquor sufficient for all

the purposes of scouring, cleaning, conversion into commercial

ammonia-salts, &c. It may be further purified by a third distillation; the

second portion of each operation being transferred again to the still with

the next fresh charge of gas-liquor.

2. A modification of Coffey's still,[43] patented by Mr W. E. Newton

(1841), under the name of the 'AMMONIA STILL,' is now extensively and

successfully employed in this manufacture. By its use ammonia may be

obtained from 'gas-liquor,' 'bone-spirit,' or any other ammoniacal liquor

or solution, and even from solutions of the salts of ammonia, of almost

any density, and of considerable purity; and this by a process which is

continuous and inexpensive. The body of the apparatus is formed of wood,

the chambers are lined with lead, and the diaphragms are of perforated

sheet iron. The management of the apparatus varies with the form in which

it is desired to obtain the product. When the ammonia is required to leave

the upper chamber of the rectifier in the form of gas, either pure or

impure, the steam which ascends, and the current of 'ammoniacal liquor'

which descends, are regulated in such relative proportions that the latter

remains at or near the atmospheric temperature during its passage through

some of the upper chambers, becoming successively hotter as it descends,

until at length it enters into ebullition; in which state it passes

through the lower chambers, either to make its escape, or to enter a

cistern provided to receive it. If, on the contrary, the ammonia is

required to leave the upper chamber in combination with the vapour of

water, the supply of steam entering below must be in such proportion to

that of the ammoniacal liquor supplied from above, that the latter may be

at or near the boiling temperature in the upper part of the apparatus.

Crude liquor and ammonia-salts, before being thus submitted to

distillation, are, of course, first treated with a proper quantity of

quick-lime--in the one case to remove most of the impurities, and in the

other to set the ammonia free by seizing on its acid.[44]

[Footnote 43: An _engr._ and description of this still, as employed for

spirit, is given under DISTILLATION (which _see_).]

[Footnote 44: For a full description of the "AMMONIA-STILL," _see_

Newton's 'Patent Journ.,' 'Pharm Journ.,' xiii, 64; &c.]

The water or solution contained in the first bottle or the first receiver

is found to be the strongest, provided it has been kept well cooled; and

that in the others, of progressively decreasing strength. By mixing the

contents of one bottle with another a solution of almost any strength may

be made. It is also easy to prepare liquor of ammonia of any required

strength, or to ascertain the strength of that in the receivers, by

observing the expansion of the liquid. Water, when fully saturated with

ammonia, expands from 3 volumes to 5 vols.; and in less, but corresponding

proportion, according to the quantity absorbed. All that is necessary in

practice is, that each receiver be furnished with a gauge-pipe by which

the degree of expansion may be noted. On the small scale, graduated glass

receivers may be used.

3. Mallet's Apparatus. This, which is employed in many of the large gas

works, is shown in vertical section in the accompanying woodcut. Steam is

forced into large receptacles, which are filled with gas water, by which

means the carbonate of ammonia is volatilised. When lime, as is sometimes

the case, is added, ammonia gas is evolved, and this being conveyed into

weak sulphuric acid, sulphate of ammonia is the result.

[Illustration]

The apparatus consists of two cylindrical boiler-plate vessels, A and B. A

is heated directly by the fire, and has a leaden tube, _c_, which dips

into the liquid contained in B, this vessel being so placed as to catch

the waste heat from the fire. _b_ and _e_ are man-holes; _a_ and _a'_ are

stirrers. By means of the tube _d_ the fluid from B can be run off into A.

Gas-water is poured into both vessels, and lime added; ammonia is

liberated, whilst carbonate of lime and sulphide of calcium are formed,

and these latter remain in the vessels after the volatilisation of the

ammonia. The vessel D is also filled with ammoniacal water, and when the

operation is in action this water, already warmed, is run by the aid of

the tube _h_ from D into B. E is a gas-water tank, from which D is filled

by means of _g_. The ammonia set free in A is, with the steam, conveyed by

the pipe _c_ into B, thence through _c'_ into the wash-vessel C, and

thence again through _c''_ into the first condenser, D. The partially

condensed vapour now passes into the condensing vessel F, the worm of

which is surrounded by cold water. The dilute ammonia is collected in G,

and forced by means of the pump (R) into C, from whence it is occasionally

removed by means of a syphon into either A or B. The non-condensed

ammoniacal gas is carried from G through a series of Wolfe's bottles, the

first bottle (H) containing olive oil, with the object of retaining any

hydrocarbons that may be present in the gas; the bottle J contains caustic

soda-ley, in order to purify the ammonia and retain impurities; the bottle

K is half filled with distilled water. The ammoniacal gas having passed

through K, is conveyed to the large wooden tank (lined with lead) L,

filled with diluted sulphuric acid, if it is intended to prepare sulphate

of ammonia, or with water, if solution of ammonia be required. The vessel

L is placed in a tank of water; _i_ is a small pipe for introducing acid,

while the tube leading to M serves to carry off any unabsorbed ammonia, M

being likewise filled with acid.

4. By means of Rose's apparatus, the ammoniacal gas-liquor mixed with one

third of slaked lime is heated in a boiler to a temperature of from 96° to

100°, the ammoniacal gas evolved being passed into hydrochloric acid, and

thence through charcoal into vessels containing from 120 to 150 litres of

water, which is converted into liquid ammonia of a sp. gr. 0·920.

5. In Lunge's apparatus the gas-water is heated in a boiler, and the

liberated ammoniacal gas passed into sulphuric acid.

Solution of ammonia is now seldom made by the druggist, or on the small

scale, the large manufacturing chemists supplying it at a very low rate,

and of very superior quality. In the shops it is kept of two or three

strengths.

The estimation of the strength of ammonia solutions in commerce is known

as ammonimetry, and depends upon their specific gravities. The per-centage

richness of solutions of ammonia, or of its carbonates, may be most

accurately determined, by ALKALIMETRY. For all the ordinary purposes of

commerce, and of the laboratory, the strength of pure solutions of ammonia

may, however, be inferred, with sufficient correctness, from their

density; and to this the term AMMONIOMETRY is usually restricted.

The specific gravity of the sample being found either by the

hydrometer[45] or specific gravity bottle, in the usual manner, its

per-centage strength may be seen by inspection of the following _Table_

and the _Table_ on p. 127.

[Footnote 45: An hydrometer specially weighted and graduated for this

purpose is called an AMMONIM'ETER, AMMONIOM'ETER, or AMMO'NIA-ME'TER

(AMMONIM'ETRUM, AMMONIOM'ETRUM, &c., L.)]

TABLE I.--_Showing the per-centage of_ PURE AMMONIA,

_and of_ AMMONIA-WATER _of_ ·9000, _in Water of

Ammonia, of the given specific gravities, at_ 60° Fahr.

By Dr URE.

------------+------------+----------------+------------

Sp. Gr. by | Water of | Pure | Water,

experiment. | Ammonia | Ammonia, per | per cent.

| of 900, | cent. |

| per cent.| |

------------+------------+----------------+------------

·9000 | 100 | 26·500 | 73·500

·9045 | 95 | 25·175 | 74·825

·9090 | 90 | 23·850 | 76·150

·9133 | 85 | 22·525 | 77·475

·9177 | 80 | 21·200 | 78·800

·9227 | 75 | 19·875 | 80·125

·9275 | 70 | 18·550 | 81·450

·9320 | 65 | 17·225 | 82·775

·9363 | 60 | 15·900 | 84·100

·9410 | 55 | 14·575 | 85·425

·9455 | 50 | 13·250 | 86·750

·9510 | 45 | 11·925 | 88·075

·9564 | 40 | 10·600 | 89·400

·9614 | 35 | 9·275 | 90·725

·9662 | 30 | 7·950 | 92·050

·9716 | 25 | 6·625 | 93·375

·9768 | 20 | 5·300 | 94·700

·9828 | 15 | 3·975 | 96·025

·9887 | 10 | 2·650 | 97·350

·9945 | 5 | 1·325 | 98·675

------------+------------+----------------+------------

[asterism] Strengths corresponding to sp. gr. which are not in the above

_Tables_ may be found by the 'method of differences' explained under

ALCOHOLOMETRY.

[asterism] 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._ AMMONIÆ 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 1·00000, 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 | 34·694 | ·91750 | 21·837 | ·96000 | 10·119

·87625 | 34·298 | ·91875 | 21·477 | ·96125 | 9·790

·87750 | 33·903 | ·92000 | 21·118 | ·96250 | 9·462

·87875 | 33·509 | ·92125 | 20·760 | ·96375 | 9·135

·88000 | 33·117 | ·92250 | 20·403 | ·96500 | 8·808

·88125 | 32·725 | ·92375 | 20·046 | ·96625 | 8·483

·88250 | 32·335 | ·92500 | 19·691 | ·96750 | 8·158

·88375 | 31·946 | ·92625 | 19·337 | ·96875 | 7·834

·88500 | 31·558 | ·92750 | 18·983 | ·97000 | 7·511

·88625 | 31·172 | ·92875 | 18·631 | ·97125 | 7·189

·88750 | 30·785 | ·93000 | 18·280 | ·97250 | 6·867

·88875 | 30·400 | ·93125 | 17·929 | ·97375 | 6·547

·89000 | 30·016 | ·93250 | 17·579 | ·97500 | 6·227

·89125 | 29·633 | ·93375 | 17·231 | ·97625 | 5·908

·89250 | 29·252 | ·93500 | 16·883 | ·97750 | 5·590

·89375 | 28·871 | ·93625 | 16·536 | ·97875 | 5·273

·89500 | 28·492 | ·93750 | 16·190 | ·98000 | 4·956

·89625 | 28·133 | ·93875 | 15·846 | ·98125 | 4·641

·89750 | 27·736 | ·94000 | 15·502 | ·98250 | 4·326

·89875 | 27·359 | ·94125 | 15·158 | ·98375 | 4·011

·90000 | 26·984 | ·94250 | 14·816 | ·98500 | 3·698

·90125 | 26·610 | ·94375 | 14·475 | ·98625 | 3·386

·90250 | 26·237 | ·94500 | 14·135 | ·98750 | 3·074

·90375 | 25·865 | ·94625 | 13·795 | ·98875 | 2·763

·90500 | 25·493 | ·94750 | 13·456 | ·99000 | 2·453

·90625 | 25·123 | ·94875 | 13·119 | ·99125 | 2·144

·90750 | 24·754 | ·95000 | 12·782 | ·99250 | 1·835

·90875 | 24·386 | ·95125 | 12·446 | ·99375 | 1·527

·91000 | 24·019 | ·95250 | 12·111 | ·99500 | 1·220

·91125 | 23·653 | ·95375 | 11·777 | ·99625 | ·914

·91250 | 23·288 | ·95500 | 11·444 | ·99760 | ·609

·91375 | 22·924 | ·95625 | 11·111 | ·99875 | ·304

·91500 | 22·561 | ·95750 | 10·780 |1·00000 | { 0

·91625 | 22·198 | ·95875 | 10·449 | | {or Water.

----------+------------+----------+------------+----------+------------

[asterism] The specific gravity of mixtures of pure solution of

ammonia and pure water is precisely the mean of the specific

gravities of their constituents. (Davy; Dalton; Christison.) In

all solutions of ammonia, a quantity 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 34·694% 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 potassa, 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 potassa. 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 analyses, 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''NIÆ ACE'TAS,

L.; ACETATE D'AMMONIAQUE, Fr.; ESSIGSÄURES AMMONIAK, Ger. _Prep._ 1. Take

of acetate of lime or of potassa 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 mass on cooling. Dry gaseous ammonia passed 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 mass, 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 passes off in large quantities 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 diaphoretic 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, Arseniate of.= (NH_{4})_{3}AsO_{4}. _Syn._ AMMONIÆ ARSE'NIAS,

L. _Prep._ 1. (NEUTRAL.) Saturate a warm concentrated solution of arsenic

acid with carbonate of ammonium in slight excess; evaporate by a gentle

heat, that crystals may form on cooling.

2. =Ammonium, Binarseniate 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, Arsenite of.= NH_{4}AsO_{2}. _Syn._ AMMONIÆ AR'SENIS, L.

_Prep._ From a hot concentrated solution of arsenious acid, and

sesquicarbonate of ammonium, as the last.--Used (chiefly) to make arsenite

of iron. The properties and physiological effects of the above arsenical

preparations are for the most part similar to those of arseniate and

arsenate of potassa. 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 AMMONIÆ 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 potassium. 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 potassium

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, AMMONIÆ

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., 3·3 parts at 62°, 2·5

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 assumes 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. 0·966.

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

analysis, &c. In _medicine_ it is used as a stimulant, antispasmodic,

antacid, and diaphoretic, in acidity of the stomach, dyspeptic affections,

gout, scrofula, hysteria, lowness of spirits, epilepsy, &c.; and in the

convulsions attending dentition. 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 quantity,

is often productive of very serious consequences--slow fever, debility,

emaciation, scurvy, loss of teeth, hæmorrhage, general cachexy, and even

death. The antidote and restorative treatment are, the free use of

lemon-juice, wine or malt-liquors, new milk, and antiscorbutic vegetables,

with a generous diet, of which the red meats form a large

proportion.--_Dose._ As a stimulant or diaphoretic, 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 cock 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 passing 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 passing 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.

[Illustration]

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 passing 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 accumulated 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 passed off as before,

or made to traverse the fire of the steam-engine before entering the

chimney-shaft. The quantity 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 pass 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 1·25, 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.

[Illustration]

The crude dried salt of the last process is finally purified by

sublimation. For this purpose cast-iron-pots lined with clay, and heated

from below and by flues round their sides, are employed. (See _engr._) The

crude grey salt is beaten down into these pots until they are about 2-3rds

filled, when the heads or capitols are fitted on, and heat applied. The

latter are very heavy, being usually made of lead (sometimes of iron), and

have the form of a dome, or a hemispherical cup, with a small tube or hole

at the apex, in which a plug is loosely placed, to permit the escape of

steam. These domes or heads are so made as to fit closely and firmly on

the flat rim or flange of the 'sublimers,' and are retained in their

places, during use, both by their weight, and by 2 or 3 clamps provided

for the purpose. They are also furnished with 3 rings, set at equal

distances, to allow of their being lifted off, or moved, by means of a

pulley and chains. The due application and regulation of the heat is here

of the utmost importance. If the temperature employed be too high, the

sublimed salt will be contaminated with empyreumatic matter, while some of

it will be carried beyond the dome and lost; and if it be extreme, the

head may be altogether blown off, and the contents of the pan scattered

about the building; whilst on the other hand, if the heat employed be too

low, the resulting cake of sal ammonia will be soft, spongy, and either

grey or yellowish. The proper temperature is said to be known by two or

three drops of water readily boiling, and being dissipated in vapour, when

placed on the head or cover of the sublimer; but it should not 'spit' or

'dance about,' or be raised by the heat out of contact with the metal. The

usual practice is to keep the fires "briskly up until the sublimers and

their surroundings attain a sufficient degree of heat; they are then

slackened, and maintained at a mean temperature." (Muspratt.) The

sublimation occupies from 5 to 9 days; but it is customary to raise the

heads once, or even twice a week, to ascertain the progress made; the

fires having been purposely neglected or checked for some hours

previously. The process is finally stopped before the whole of the crude

salt in the pots is volatilised; since the heat required for that purpose

would lead to the decomposition of the carbonaceous impurities, and cause

them to emit volatile hydrocarbons, which would materially lessen the

purity and beauty of the product. The unsublimed portion in the pots forms

a conical mass, which is technically called the 'yolk.' This is shown in

the second engr. (see _below_), in which the latest improvements in the

form of the subliming apparatus are also exhibited.

[Illustration]

The sublimation having been carried to a sufficient extent, the fires are

allowed to die out. The domes, after cooling, are lifted off, and the

attached hemispherical cakes or 'bells' of SAL AMMONIAC or HYDROCHLORATE

OF AMMONIA at once removed. These vary from 2 to 5 inches in thickness,

and from 45 or 50 _lbs._ to 1000 _lbs._, and upwards, in weight, according

to the size of the sublimers in which they have been produced. They are

generally nearly pure, except in the outer part which has been in contact

with the metal. From the subliming-house they are taken to the store or

packing-house, and after having been scraped, to remove the discoloured

portion before alluded to, are either preserved entire, or are broken up

into convenient pieces, which are then packed in casks or barrels, and in

either state are ready for the market.

When sulphuric acid[49] is used to neutralise the ammoniacal liquor, the

process is generally, for the most part, the same as when hydrochloric

acid is employed; but here the brown salt obtained by the crystallisation,

and subsequent desiccation, is crude SULPHATE OF AMMONIA, instead of the

hydrochlorate. It is intimately mixed with about an equal weight of

chloride of sodium (common salt) before being put into the sublimers.

[Footnote 49: Sp. gr. 1·33 to 1·38.]

In some cases, particularly where the ammoniacal liquor is rich in

carbonate of ammonia, gypsum is employed as a source of sulphuric acid.

(See _below_.)

Another method is to convert the solution of the crude sulphate into a

solution of the hydrochlorate, during the process, by the addition of

chloride of sodium. Both these last methods are described below.

2. From BONE-LIQUOR, &c.[50]--The ammoniacal liquor technically called

'bone-liquor' or 'bone-spirit,' and formerly known under the name of

'spirit of hartshorn,' is essentially a solution of carbonate of ammonia

more or less contaminated with volatile empyreumatic oil. Its conversion

into SAL AMMONIA may be easily effected by saturating it with hydrochloric

acid, evaporating the resulting neutral solution in lead or iron boilers

until a pellicle begins to form, then pumping or running off the hot

liquors into the crystallisers, and, lastly, draining and drying the

crystals. The salt thus obtained may be purified either by sublimation or

by recrystallisation. The whole series of processes closely resemble those

already described, except in being less troublesome, owing to the absence

of the tarry and other foreign matters which impede and complicate them

when gas-liquor is employed.

[Footnote 50: That employed in England is chiefly obtained, as already

mentioned, from the manufacturers of bone-black or animal charcoal; but,

on the Continent, the liquor obtained by a like destructive distillation

of various animal offals (blood, flesh, horn, hoofs, woollen rags and

waste, hair, scrapings of hides, leather cuttings, &c.) is employed for

the same purpose. The preparatory process by which this liquor is obtained

is essentially the same in each case; except that with animal offal the

temperature should not exceed a red-brown heat, in order that the

resulting charcoal may afterwards serve to make ferrocyanide of potassium

and Prussian blue. These liquors have usually a density ranging between 8°

and 9° Baumé (Ure; = sp. gr. 1·056 to 1·063).]

Another method adopted, particularly on the Continent, and one equally

applicable to any crude ammoniacal liquor rich in free ammonia or its

carbonates, is to employ sulphate of lime instead of sulphuric acid to

neutralise the alkali. For this purpose the ammoniacal liquor is passed

through a series of three or four covered wooden filters lined with lead,

each containing a layer of crushed gypsum to the depth of 3 or 4 inches.

These filters are usually set on 'stages' one above another, and each

communicates with a cistern placed beneath it by means of a leaden pipe

furnished with a stop-cock. This last is not opened untill the liquor has

remained some little time in the filter; and a pump throws back once, or

oftener, upon each filter, what has already passed through it, before it

is allowed to run into the next lower one. The 'liquor' in each filter is

not allowed to stand higher than from 2 to 3 inches above the surface of

the gypsum; and the lowest or last filter is supplied with fresh gypsum at

each separate charge of fresh liquor. A little water is lastly passed

through the filters to wash out the portion of ammoniacal liquor absorbed

or retained by the filtering media. In this way the gypsum of the filters

is converted into carbonate of lime at the expense of the carbonate of

ammonia in the solution; whilst the ammonia of the latter decomposes the

gypsum, and becomes converted into sulphate of ammonia, which, with some

free ammonia, is found in the filtrate. Sulphuric acid is next added to

the filtered liquor to completely neutralise the free and carbonated

alkali still existing in it; after which it is evaporated in a leaden

boiler, with frequent skimming to remove floating oil, until of the sp.

gr. 1·160. Chloride of sodium (common salt), in sufficient quantity to

convert all the sulphate of ammonia in the liquid into hydrochlorate, by

double decomposition, is now added, with constant stirring; after which

the clear portion is either pumped or syphoned off into a somewhat deep

reservoir or tank, where it is allowed to settle. The liquid after

sufficient repose is pumped from the reservoir to the boilers, and

evaporated, with frequent agitation, so long as the sulphate of soda now

existing in it falls to the bottom in granular crystals. These crystals

are, at intervals, scraped to the cooler portion of the pan or boiler,

whence they are removed by copper rakes and shovels, into

draining-hoppers, placed near the edges of the pan. The liquor in the

boiler is now a strong solution of sal ammoniac, but still containing a

little sulphate of soda, from which it has to be freed by crystallisation.

With this object it is further concentrated, and then run or pumped into

the crystallisers. In 30 or 40 hours, or longer, the mother-liquor is run

or pumped off. The mass of newly-formed crystals is then drained, and

slightly washed, first with a little weak solution of sal ammoniac, and

next with a very little cold water; after which they are again well

drained. The crude HYDROCHLORATE OF AMMONIA, thus obtained, is converted

into the pure salts, by desiccation and sublimation, as before.

In France, where this method is very generally employed, the sublimation

is commonly conducted in stoneware or earthenware balloons or bottles

coated with loam, of about 18 to 20 inches in height in the body, and

either surmounted with inverted 'cups' or 'heads' 10 or 12 inches high, or

simply covered with a tile, when (in the latter case) the sublimate

collects in the upper part or neck of the balloon, which is above the

action of the fire. A number of these vessels are set on the dome of a

furnace, which is perforated with holes or slits, to allow the heat to

pass through; whilst their necks or heads are sheltered from the action of

the fire by plates of iron or earthenware, having semi-circular

indentations on their edges, so that when placed together they form a

level surface, through which the necks of the sublimers protrude, and fit

closely. The fire is nicely regulated, so as to cause the salts to

condense in the upper and cooler part of the vessels, or in the heads, as

the case may be; and great care is taken to occasionally clear the necks

with a skewer, to prevent choking, and consequent bursting.

In Scotland, where a similar process is also commonly pursued, the

sublimers, according to Dr Ure, are generally "cast-iron pots, lined with

fire-proof tiles; the condensation being effected in globular heads of

green glass, with which each of the iron pots are capped."[51]

[Footnote 51: Ure's 'Dict. of Arts, M., & M.,' 5th Edn., i, p. 143.]

_Ratio._ Gas-liquor contains carbonate of ammonium (chiefly), with

chloride, sulphate, hydrosulphate, cyanide, sulphocyanide, &c., of the

same radical. On neutralisation with hydrochloric acid, or sulphuric acid,

these are converted into chloride or sulphate of ammonium, according to

the acid used. By sublimation with chloride of sodium, the sulphate of

ammonium is converted, by double decomposition, into chloride of ammonium,

which sublimes; and sulphate of sodium, which remains in the subliming

pot. A similar change occurs when the solution of the sulphate, prior to

crystallisation, is decomposed by the addition of chloride of sodium, or

any other chloride. When the 'gas-liquor' is at once converted into

chloride of ammonium by the addition of hydrochloric acid, the sublimation

merely purifies the salt. Like changes occur when bone-spirit is employed.

_Comp._ Chemically considered, this salt consists of equal VOLUMES of

gaseous ammonia and hydrochloric acid gas condensed into the solid form;

or, by WEIGHT, according to the ammonia-theory, of--

Atoms. Equiv. wt. Per cent.

Ammonia (NH_{3}) 1 17· 31·78

Hydrochloric acid (HCl) 1 36·5 68·22

--- ----- ------

Hydrochlorate of Ammonia (NH_{3}HCl) 1 53·5 100·