AMMOATA.-

—Estimation. 201

Ammonium ocquioarbonato. wSouS

(NUJjHatCOsJaHaO = (NH^COjHaO + 2(N1IJ1IC0 3

i

of nitrate of silver solution; a white precipitate inthese shows the presence of sulphuric acid in the

former, and of hydrochloric acid in the latter.

But the neutral carbonate is very unstable, and

Hyposulphites are detected by neutralizing a por-

speedily resolves itself into the more stable am-

tion of the salt with acetic acid, and adding nitrate

monium bicarbonate, at the same time giving off

of silver ; a precipitate is obtained, which is white at

water and ammonia thus:—

first, but soon turns black, in consequence of the

neute™ito. as

(nh 4 )oCo 3 ,ii 3 0 = n;t 3 + h 2 o + (Nhjiiuo,

oxide of silver being reduced. Lead is detected bytransmitting a stream of sulphuretted hydrogen gasthrough a solution of the salt, which occasions a

The same change hikes place when solid sesqui-

black precipitate if lead be present.

carbonate of ammonia is exposed to the air; hence

Commercial carbonate of ammonia is used for

the use of ammonium sesquicarbonate as smelling

cleansing woollen cloths, for the extraction of grease

salts. Bicarbonate of ammonia, remaining after the

in the manufacture of most fabrics; and when free

exposure of the sesquicarbonate, is not so pungent

from organic and mechanical impurities it is used in

as the salt which produces it. Medically, it is known

the preparation of yeast and baking powders.

as mild carbonate of ammonia. It yields a precipi-

In agriculture, the salts of ammonia are most valu-

tate with bichloride of platinum in the presence of

able, increasing in a remarkable manner the fertility

hydrochloric acid; with copper salts it gives the

of the land, provided the other constituents peculiar

characteristic blue colour produced by ammonia;

to the crop be present; lienee they are to be found

with the salts of the alkaline earths it does not yield

in all good manures, the value of which they greatly

an immediate precipitate; on boiling the mixture,

enhance. Ammonia constitutes one-fifth of the

however, the insoluble earthy carbonate falls down.

weight of genuine Peruvian guano; stable manure

Rose states that the composition of the sesqui-

also contains ammonia in large quantities, and it is

carbonate varies with the mode of preparing it.

one of the valuable constituents of bone manure.

When obtained by the sublimation of the salt from

Ammoniacal salts arc extensively used hi calico-

chloride of ammonium—or any other compound of

printing, in the preparation of leather, and in pewter-

ammonia—and carbonate of lime, the product is a

ing; for the last process, as well as for tinning

sesquisalt; but on subsequent sublimation, for the

sheet-iron and iron vessels, the chloride is preferred;

purpose of purifying, he says that it is only four-

on account of its volatility, it substitutes an ammonia-

fifths sesquicarbonate, as his analysis indicates.

cal atmosphere for the ordinary air, and thus prevents

Sesquicarbonate of ammonia possesses a pungent

the oxidation of the tin.

odour, a hot and saline taste, and a powerful alkaline

Estimation .of Ammonia.—T o the manufacturer

reaction. The aqueous solution of this salt is used

who employs ammoniacal salts it is very necessary

in medicine as a stimulant, and is a useful source of

that lie should be able to ascertain their real value,

other annnoniacal salts. Bicarbonate of ammonia

and what amount of work he can perforin with their

crystallizes from the hot concentrated solutions of

aid. The mode commonly adopted is the deter-

the sesquicarbonate, or it may be precipitated by

minatioii of the amount of alkali with a standard

alcohol. By the action of heat the sesquicarbonate

acid. The salt may likewise be distilled with potash

decomposes into various ammonium compounds, con-

through a Liebig ’s condenser into a flask containing

taining more or less carbonic acid; the sesquicar-

standard acid coloured with a few drops of litmus

bonate of commerce is a mixture of several of these.

tincture. The tube from the receiver should not dip

Pure ammonium sesquicarbonate is obtained by

into the acid. An U tube containing dilute standard

dissolving the commercial salt in strong ammonia, at

acid up to the bend should be connected with the

about 86° Fahr. (30° C.), and allowing the solution

flask to prevent any loss of ammonia. The liquid is

to crystallize. It then fonns transparent right-reetan-

to be kept boiling gently until the drops, as they fall

gular prisms, with the faces of the corresponding

into the acid, cease to render the acid with which

rhombic octahedron resting on the angles. The iin-

they first come in contact blue. The contents of the

purities of the commercial sesquicarbonate are organic

flask and U tube are then mixed together, and tit-

matter and small portions of the salt from which it is

rated with a standard alkali. The amount of acid

prepared, which pass over to the chambers unchanged;

which has been neutralized by the ammonia is thus

sometimes it contains hyposulphite of ammonia from

ascertained.

the deconqrosition of the sulphate of ammonia, when

Estimation as Chloride .—In pure solutions of am-

this salt has been used, and also traces of lead, derived

monia, or any of its combinations with a feeble

from the leaden chambers.

volatile acid, the alkali is readily determined by satur-

Organic matter is detected by simply dissolving

ating with hydrochloric aoid, and evaporating the

the impure article in water, when a solution of a

solution to dryness in a water-bath, till the whole

brownish or even blackish colour is produced, while

of the free acid and moisture are removed; the dry

the pure salt affords a colourless liquid. Sulphates

residue, accurately weighed, gives the amount in the

or chlorides are detected by dissolving the salt in

form of ammonium chloride. Should the solution

water, adding a few drops of nitric acid, and dividing

contain only ammonium chloride, evaporation of the

the solution into two portions; to one part chloride

water and weighing of the dry residue will give at once

of barium is to be added, and to the other a few drops

the amount of that salt, and the ammonia contained

VOL. I.

26