+------------------+-------------------+
| | Whitby, Yorkshire.|
| | (_Richardson._) |
| +--------+----------+
| | Top | Bottom |
| | rock. | rock. |
+------------------+--------+----------+
|Sulphide of iron | 4·20 | 8·50 |
| (_pyrites_) | | |
|Silica | 52·25 | 15·16 |
|Protoxide of iron | 8·49 | 6·11 |
|Alumina | 18·75 | 18·30 |
|Lime | 1·25 | 2·15 |
|Magnesia | ·91 | ·90 |
|Oxide of manganese| traces | traces |
|Sulphuric acid | 1·37 | 2·50 |
| (SO_{3}) | | |
|Potassa | ·13 | traces |
|Soda | ·20 | traces |
|Chlorine | traces | traces |
|Coal | 4·97 | 8·29 |
|Water | 2·88 | ·00 |
|Loss | 4·60 | (?) |
| | | |
+------------------+--------+----------+
| | 100· | 100· |
+------------------+--------+----------+
+---------------------+------------------------------+
| | Campsie, near Glasgow. |
| | (_Ronalds._) |
+---------------------+---------+----------+---------+
| | Top | Top | Bottom |
| | rock. | rock. | rock. |
|---------------------+---------+----------+---------+
|Sulphide of iron | 40·52 | 38·48 | 9·63(?)|
| (_pyrites_) | | | |
|Silica | 15·40 | 15·41 | 20·47(?)|
|Protoxide of iron | ... | ... | 2·18 |
|Alumina | 11·35 | 11·64 | 18·91(?)|
|Lime | 1·40 | 2·22 | ·40 |
|Magnesia | ·50 | ·32 | 2·17 |
|Oxide of manganese | ·15 | ... | ·55 |
|Sulphuric acid | ... | ... | ·05 |
|Potassa | ·90 | ... | 1·26 |
|Soda | ... | ... | ·21 |
|Carbon or | 27·65(?)| 28·80 | (?) |
| bituminous matter | | | |
|Coal | ... | ... | 8·51 |
|Water | ... | ... | 8·54 |
|Loss | 2·13(?)| 3·13 | 1·59(?)|
+---------------------+---------+----------+---------+
| | 100· | 100· | 100· |
+---------------------+---------+----------+---------+
Alum-rock, or alum-stone, is a species of impure alunite, and is not of
very common occurrence. That of Tolfa, near Civita Vecchia, according to
Klaproth, consists of--
Silica 56·5
Alumina 19·
Sulphuric acid (SO_{3}) 16·5
Potassa 4·
Water 3·
Loss 1·
------
100·
which exhibits an excess of about 3% of sulphuric acid, and about 14% of
alumina, more than are requisite to form alum with the 4% of potassa;
proportions which, therefore, require to be supplemented with a potassium
salt during the process of manufacture. The alum-stone of Mont d'Or
contains, according to Cordier, 1·4% of oxide of iron.
The presence of lime in alum-ore is most prejudicial, owing to its
affinity for sulphuric acid being greater than that of either alumina or
iron. Ores containing it in any quantity are, therefore, unfitted for the
manufacture of alum. Magnesia is also prejudicial; but in this case the
sulphate of magnesia left in the mother-liquors is not wholly valueless,
as it may be crystallised and sold as 'Epsom-salt,'--a thing which is
actually done in some English alum-works.
The potash-salt employed by the alum-makers is either the sulphate or the
chloride--chiefly the latter; its sources being the waste liquor of
soap-works, saltpetre refineries, and glass-houses. Wood-ashes, although
rich in potash, do not answer well unless freed by lixiviation from the
large amount of carbonate of lime which is always present in them.
The ammonia-salt used in making alum is generally the crude sulphate
prepared from the ammoniacal liquor of gas-works, or that from the
manufacture of sal-ammoniac by the destructive distillation of animal
matter. Both these liquors may be used without previous conversion into
sulphate of ammonia whenever there is an excess of sulphuric acid in the
aluminous solution.
Soda-salts are seldom, if ever, used as precipitants in the manufacture of
alum, on account of the easy solubility of the resulting SODA-ALUM--a
property which unfits them for this purpose. See ALUMS, AMMONIA, DYEING,
MORDANTS, POTASH, SULPHURIC ACID, &c. (also _below_).
=Alum, Ammonia.= (NH_{4})_{2}SO_{4} . Al_{2}(SO_{4})_{3} . 24 Aq. _Syn_.
(ALUMEN; ALUM; B. P.), ALU'MEN AMMONIA'TUM, L.; ALUN D'AMMONIAQUE, A.
AMMONIACAL, Fr. This is an alum in which the sulphate of potassium is
replaced by an equivalent of sulphate of ammonium. It is prepared by
adding crude sulphate of ammonium to solution of sulphate of aluminum; or
gas-liquor, putrid urine, &c., to the acid-sulphate.
Much of the common alum, especially that prepared on the Continent,
contains both potassium and ammonium; and recently enormous works for its
manufacture have been established in England. As an astringent, and as a
source of alumina in dyeing, it resembles potash-alum (_i. e._ ordinary
alum). It may, however, be readily distinguished from the latter by the
fumes of ammonia which are evolved when it is moistened and triturated, or
heated, with caustic potassa or quick-lime; and by the residuum of its
exposure to a white heat being pure alumina. See ALUM (_antè_).
=Alum, Basic.= A variety of alum found native at Tolfa. On calcination and
subsequent lixiviation it yields ordinary alum. A like substance falls as
a white powder, when newly precipitated alumina is boiled in a solution of
alum.
=Alum, Baumé's.= Alum-white. See WHITE PIGMENTS.
=Alum, Dried; Alum, Burnt.= _Syn_. ALU'MEN US'TUM, A. EXSICCA'TUM (B. P.);
ALUN SEC, Fr.; GEBRANNTER ALAUN, Ger.; ALUME CALCINATO, Ital. Alum
deprived of its water of crystallisation by heat.
_Prep._ Take of alum, 4 oz. Heat the alum in a porcelain dish or other
suitable vessel, till it liquefies, then raise and continue the heat, not
allowing it to exceed 400°, till aqueous vapour ceases to be disengaged,
and the salt has lost 47 per cent. of its weight. Reduce the residue to
powder, and preserve it in a well-stopped bottle.
_Prop., &c._ Similar to those of common alum, but it is rather more
astringent, and is less soluble. When moistened, or placed in contact with
water, it resumes its water of crystallisation with evolution of
heat.--_Dose_, 10 to 20 gr.; in colic (especially painters' colic),
hæmoptysis, &c. It is chiefly used as an escharotic, to destroy 'proud
flesh,' &c. It must be kept in a stoppered bottle.
=Alum, Chrome.= See ALUMS (in Chemistry).
=Alum, I'ron= (-[)u]rn). _Syn_. ALU'MEN FER'RICUM, SUL'PHAS FER'RI ET
POTAS'SÆ, FER'RI PEROX'IDI POTASSIO-SUL'PHAS, &c., L.
_Comp._ K_{2}SO_{4} . Fe_{2}(SO_{4})_{3}.24Aq.
_Prep._ Take of peroxide of iron, 9 lbs.; sulphuric acid 14 lbs.;
dissolve, dilute the mixture with water, q. s., and add of potassium
sulphate, 10 lbs.; evaporate, and crystallise.
_Prop., &c._ Crystals, beautiful octahedrons of a pinkish or pale violet
colour. It is strongly recommended, by Dr Tyler Smith, as a chalybeate
tonic, and has been used by him, at St. Mary's Hospital with marked
success. It has also been used as a mordant, in dyeing black.--_Dose_, 1/2
gr. to 5 gr.
=Alum, Ro'man.= _Syn_. RED ALUM*, ROACH A., ROCHE A., ROCK A.*; ALU'MEN
ROMA'NUM, A. RU'BRUM, A. RU'PEUM, &c., L.; ALUN ROMAIN, A. DE ROCHE, Fr.;
ALUME DI ROCCA, It. In small fragments, covered with a reddish powder
(ALUMEN RUBRUM VE''RUM); originally imported from Civita Vecchia, where it
occurs native. It is much esteemed by dyers from being nearly free from
iron-alum. That now sold for it in England is ordinary alum coloured with
Venetian red, Armenian bole, or rose-pink (ALUMEN RUBRUM SPU''RIUM). This
is done by shaking the fragments in a sieve over a vessel of hot water,
and then stirring them up with the colour, until the surface is uniformly
tinged with it. In genuine roach-alum the colour not only covers the
surface, but also partially pervades the substance of the crystals. The
name was formerly also applied to a pure white variety of alum, prepared
at Tolfa; but it is now, in English commerce, exclusively given to common
alum artificially coloured.
=Alum, Saccharated.= Alum, 6 oz., white lead 6 drms., sulphate of zinc 3
drms., sugar 1-1/2 oz. Mix the ingredients reduced to powder into a paste,
with vinegar and white of egg. Used in eye waters and cosmetic washes.
=Alum, So'da.= _Syn_. SULPHAS ALUMINÆ ET SODÆ, L. _Comp._ Na_{2}SO_{4} .
Al_{2}(SO_{4})_{3} . 24Aq. An alum in which the potassium sulphate of
common alum is replaced by a like salt of sodium. It does not occur in
commerce. (Vide _suprà_ et _infrà_.)
=ALUM-EARTH.= Alumina.
=ALUM MOR'DANTS.= In _dyeing_, mordants having for their basis either
common alum or the acetate or sulphate of aluminum. See ALUMS and
MORDANTS.
=AL'UM-ROOT.= _Syn._ AMER'ICAN SAN'ICLE; HEU'CHERA (Ph. U. S.), L. The
root of _heuchera America'na_ (Linn.), a plant of North America. It is
powerfully styptic and astringent; and is used chiefly as an external
application in cancer.
=ALUM-WHITE.= See WHITE PIGMENTS.
=AL'UMS.= _Syn._ ALU'MINA (pl. of _alu'men_), L. In _chemistry_, a term
applied to a series or group of salts having potassium alum for their
type, which they resemble in crystalline form and constitution.
It is found that the aluminum of common alum may be replaced by any other
metal having a like nature, without affecting the leading characteristics
of the salt; and further, that in the newly formed compound, as in
potassium-alum, the second sulphate may also be replaced under the like
conditions. All the alums crystallise in octahedrons or cubes, and they
all contain the same number of molecules of water. The alums of commerce
(or alums proper) all contain aluminum sulphate and an alkaline sulphate.
_Prep._ All the alums may be made by mixing together solutions of the
respective sulphates in equivalent proportions, when crystals may be
obtained by evaporation in the usual manner. The presence of sulphuric
acid, in slight excess, assists their crystallisation.
=AL'UMED= (al'[)u]md). Mixed or impregnated with alum. In _dyeing_,
mordanted with alum.
=ALU'MEN= (-l'[=o][=o]-). [L.] Alum; the pharmacop[oe]ial name of alum.
(See _above_.)
=ALUMINIUM.= _Syn._ ALUMINUM (which _see_).
=ALUMINOUS.= In _mineralogy_, of, resembling, or containing aluminum. In
_chemistry_, containing or obtained from alum.
=ALUMINUM.= [Eng., Fr., L.] _Syn._ ALUMINIUM, Eng., Fr., L.; ALUMIUM, Ger.
A metallic radical or element very abundantly distributed, united with
silica. Discovered by M. Wöhler, who succeeded in obtaining it as a grey
metallic powder (A.D. 1827); and later (1845), under the form of globules
exhibiting the leading characteristics of the metal. In 1854, M. Dumas
announced to the 'Academy of Sciences,' that M. St. Clair Deville had
procured pure aluminum from clay, and exhibited several specimens of
considerable size and beauty. The result was a general impression that it
might be easily obtained in any quantity, and ultimately at a reasonable
price; expectations which have been only partly, though to a great extent
fulfilled, owing to the expense and trouble of the process,
notwithstanding recent improvements.
_Prep._ (M. Deville; A.D. 1854-59.)--A quantity of chloride of aluminum,
varying from 200 to 300 grammes (say from 6 to 10 oz.), is introduced into
a wide glass or porcelain tube, between two plugs of asbestos to retain it
in position, and a current of hydrogen (thoroughly dried by passing first
through concentrated sulphuric acid, and then through a tube containing
fused chloride of calcium) passed over it; a gentle heat being at the same
time applied to the part of the tube containing the chloride, to drive off
any free hydrochloric acid which might have been formed by the action of
the air upon it. A small porcelain boat, containing sodium, is now
introduced at the other extremity of the glass tube, which is then again
closed; and when the sodium is fused, the chloride is sufficiently heated
to cause its vapour to come into free contact with it. A powerful reaction
ensues, with the evolution of much heat, and this continues as long as any
undecomposed sodium remains to act on the passing vapour. The mass in the
boat, which is now a mixture of the double chloride of aluminum and
sodium, in which small globules of the newly reduced metal are suspended,
is allowed to cool in the hydrogen; after which it is treated with water,
to remove the soluble double chloride. The residuum, consisting of small
globules of aluminum, is, lastly, reduced to a solid button or mass, by
fusion, at a strong heat, under a layer of the fused double chloride of
aluminum and sodium.
On a large scale two cast-iron cylinders are employed, instead of the
glass or porcelain tube just referred to; the anterior one of which
contains the chloride of aluminum, and the posterior one a tray holding
the sodium, of which 10 or 12 lbs. are commonly operated on at once. These
cylinders are united by means of a smaller intermediate one, filled with
clean scraps of iron, which serve to separate iron, free hydrochloric
acid, and chloride of sulphur, from the vapour of the chloride of
aluminum, as it passes through them. During the passage of the vapour of
the chloride this smaller cylinder, or tube, is kept heated to from 400°
to 600° Fahr.; but the two other cylinders are only very gently heated,
since the chloride is volatilised at a comparatively low temperature, and
the reaction between it and the fused sodium, when once commenced, usually
generates sufficient heat for the completion of the process.
Occasionally a mixture of the double chloride of aluminum and sodium, 40
parts; chloride of sodium 20 parts; fluor spar, 20 parts; each separately
dried, powdered, and then blended together; sodium, in small pieces, 7-1/2
to 8 parts, are used instead of the last.
It is likewise made from a mixture of cryolite and fused chloride of
potassium, of each, in powder, 5 parts; sodium, 2 parts; a cast-iron
crucible being employed; the resulting minute globules being collected and
fused to a button under a layer of the double chloride of aluminum and
sodium.
_Prop., &c._ Aluminum, when quite pure, closely approaches silver in
appearance, except in being rather less white and lustrous than that
metal. Ordinary specimens, called pure, have a slight bluish tint or
tin-white colour, with a perfect lustre, but far inferior to that of pure
silver. Sp. gr. 2·56, which by hammering may be raised to 2·67. It is both
ductile and malleable; fuses at a temperature between the melting-points
of zinc and silver; is not affected by either damp or dry air, or by
oxygen at ordinary temperatures, or by water whether cold or boiling; even
steam, at a red heat, is only slowly decomposed by it. It is not acted on
by nitric acid, however concentrated, unless boiling, and then very
slowly; nor by dilute sulphuric acid, sulphuretted hydrogen, and the
sulphides, or even the fused hydrates of the alkalies. It is, however,
readily dissolved by hydrochloric acid, with the evolution of hydrogen,
even in the cold; and by a concentrated mixture of nitric and sulphuric
acid. It is feebly magnetic, conducts electricity about eight times better
than iron, and is more electro-negative than zinc. Commercial specimens,
owing to the presence of iron and silicon, and often zinc, usually slowly
tarnish in damp air, and possess the other properties described above in a
somewhat diminished degree.
In a finely divided state, particularly in the state of powder or minute
scales in which it was originally obtained, when heated to redness, it
catches fire and burns with great rapidity in the air, and in oxygen gas
with intense brilliancy, the product in each case being alumina.
Aluminum unites with the other metals, forming ALLOYS, of which some
promise to be of great value in the arts. An alloy of 100 parts of
aluminum with 5 parts of silver may be worked like the pure metal, but is
harder and susceptible of a finer polish, whilst its property of not being
affected by sulphuretted hydrogen and acids remains unimpaired; even 3% of
silver is said to be sufficient to impart to it the full brilliance and
colour of pure silver. An alloy containing 10% of gold is softer and
scarcely so malleable as the pure metal. With 8% of iron, or 10% of
copper, it still remains tough and malleable; but a larger proportion of
either of these metals renders it brittle.
The presence of 2 or 3% of zinc destroys its ductility and malleability,
and also impairs its colour and lustre; whilst less than even 1/4% of
bismuth renders it brittle in a high degree. Small quantities of aluminum
added to other metals change their properties in a very remarkable manner.
Thus, copper alloyed with 10%; of aluminum has the colour and brilliancy
of gold, is harder than bronze, very malleable, and may be worked at high
temperatures easier than the best varieties of iron; and with 20% is quite
white, and closely resembles silver. With more than 12% of aluminum the
alloy is harder, but brittle. The alloy formed of 100 parts of silver with
5 parts of aluminum is as hard as the silver of our coinage, whilst the
other properties of the latter metal remain unaltered.
_Uses._ The valuable properties of aluminum adapt it to numerous
applications in the arts and everyday life. Hitherto these have been very
limited, owing to its comparatively high price; which, notwithstanding it
has fallen considerably, is still sufficient to prevent its general or
even extensive application. The 'eagles' of the French army have been made
of it, as well as certain articles of jewelry, plate, &c., as brooches,
bracelets, chains, spoons, and other ornamental and useful objects. Owing
to its low sp. gr., it has been used as a suitable material for the minute
decimal weights of chemists, for military helmets, trumpets, &c. A few
cornet-à-pistons, for which its lightness and sonorousness admirably adapt
it, have actually been made of it. Its power of resisting oxygen,
sulphuretted hydrogen, moisture, &c., would render it invaluable as a
coating to metals, particularly iron and lead, to protect them from rust
or corrosion, did not its price intervene. As an internal coating for
water-pipes, cisterns, &c., no other substance, except gold and platinum,
is so well adapted. In _chemistry_, capsules, tubes, &c., either made of
or coated with it, may be often advantageously substituted for those of
platinum.
In addition to what has been said above, it may be observed that, in
preparing aluminum, the chief care should be to avoid accidents or failure
by the employment of too high a temperature, and to avoid the product
being contaminated with other metals or with carbon. To ensure the purity
of the metal is a matter of the greatest difficulty, owing to the facility
with which foreign matters are taken up, during the process, from the
materials of which the apparatus is composed; and from the substances from
which it is prepared being seldom absolutely pure. Indeed, it is not too
much to assert that chemically pure aluminum has not yet been obtained;
and that even a very close approximation to it is of very rare occurrence.
Whenever a copper boat is used to hold the sodium, the product is always
contaminated with copper. Chloride of aluminum always contains some of the
chlorides of iron and silicon, both of which are volatile, and probably
takes up a further portion from the porcelain or earthenware used to form
the apparatus. Sodium also is seldom uncontaminated with carbon or some
compound of it; in which case, and likewise when it is not carefully freed
from the naphtha in which it has been preserved, the product always
contains carbon. The crucible, whether of porcelain or iron, in which the
final fusion is made, also contributes to contaminate the metal. Hence the
inferior whiteness and brilliancy of commercial specimens of aluminum; a
metal which, in its absolutely pure state, may be reasonably inferred to
be as superior in the above respects to silver as silver is to tin.
Commercial aluminum contains from 88 to 94 per cent. only of pure
aluminum, and from 1 to 4 per cent. of iron, 1/2 to 3 per cent. of
silicon, and from 1 to 6 per cent. of copper.
Aluminum salts are generally colourless, soluble, and crystallise with
difficulty, and are distinguished as follows:--
_Tests._--1. Ammonia and the alkaline carbonates throw down a bulky white
precipitate (hydrate of aluminum) from solutions of its salts, which is
insoluble in excess of the precipitant.--2. Pure potassa and soda throw
down white gelatinous precipitates, freely soluble in excess of the
precipitant; from which the hydrate of aluminum is reprecipitated by
chloride of ammonium, even in the cold:--3. Phosphate of ammonium gives a
white precipitate--4. Iodide of potassium produces a white precipitate,
passing into a permanent yellow:--5. Sulphuretted hydrogen gives no
precipitate:--6. Sulphydrate of ammonium precipitates alumina from these
solutions:--7. Bisulphate of potassium, added to concentrated solutions,
gives a precipitate of octahedral crystals of alum:--8. At a red heat its
salts part with some of their acid; at a white heat, most of it, if not
all:--9. Aluminum compounds, ignited on charcoal before the blowpipe, and
afterwards moistened with a solution of nitrate of cobalt and again
strongly ignited, give an unfused mass, which, on cooling, appears blue by
day, and violet by candlelight; a test, however, which is inapplicable to
fusible compounds of aluminum, and such as are not free, or nearly free,
from other oxides.
=Aluminum, Acetate of.= _Syn._ ACETATE OF ALUMINA. _Prep._ Pure hydrate of
aluminum is digested, to saturation, in strong acetic acid, in the cold;
and the resulting solution, after being filtered or decanted, is either
evaporated by a very gentle heat to a gelatinous, semi-solid consistence
(its usual form), or is preserved in the liquid state. By spontaneous
evaporation it may be obtained in long, transparent crystals.
_Red liquor._ From alum, in powder, 4 parts; warm water, q. s. to
dissolve; acetate of lead, in powder, 3 parts; the solution and mixture
being effected by lengthened agitation in a tub or other wooden vessels,
and the clear liquid, after repose for a sufficient time, decanted or
drawn off from the sediment.
From alum, 2 parts; (dissolved in) warm water, q. s.; solution of
pyrolignite of lime (20° Baumé), 3 parts; as before, but allowing a longer
time for the subsidence of the precipitate, and taking more care in the
decantation than when acetate of lead is employed.
By decomposing a solution of crude sulphate of alumina with neutral or
monobasic acetate of lead.
_Prop._ Its characteristic property is the feeble affinity existing
between its acid and base, which, when it is used as a mordant, is
counterbalanced by that of the fibres of the cloth or yarn to which it is
applied. In other respects it resembles the other simple salts of alumina.
_Uses, &c._ In _dyeing_ and _calico printing_, as a mordant. In
_medicine_, properly diluted, in chronic diarrh[oe]a; and, mixed with
syrup of poppies, in slight cases of hæmoptysis (spitting of blood). It
has been employed by M. Gannal as an injection to preserve animal bodies,
which it will do for years.--_Dose_, 1/2 to 1 dr. daily, in divided
portions, taken in thin mucilage or syrup, or in barley-water; as an
injection, 10 to 20 gr., to water, 4 to 6 fl. oz., in gonorrh[oe]a,
leucorrh[oe]a, &c.
=Aluminum, Chloride of.= Al_{2}Cl_{6}. _Syn._ SESQUICHLO''RIDE OF
ALUMINUM; ALUMIN'II CHLORI'DI, &c., L. _Prep._ A thick paste made of dry
precipitated alumina, lampblack, and oil, is strongly heated in a covered
crucible until all the organic matter is carbonised. The residuum is
transferred to a porcelain tube fixed across a furnace, one end of which
is connected with another tube containing dry chloride of calcium, and the
other end with a small tubulated receiver. The porcelain tube is then
heated to redness, whilst chlorine, dried by passing through the
chloride-of-calcium tube, is transmitted through the apparatus. In one or
two hours, or as soon as the tube is choked, the whole is allowed to cool,
and the newly-formed SESQUICHLORIDE collected and preserved in mineral
naphtha for use.
On the large scale:--Chlorine, dried as before, is passed over a mixture
of pure clay, lamp-black, and coal-tar, contained in an iron retort,
similar to that used in the manufacture of coal-gas (previously ignited by
means of a suitable furnace), and connected with a cool chamber accurately
lined with tiles of earthenware. The vapours of the SESQUICHLORIDE
condense in this chamber, as a yellowish crystalline mass, which is
collected and preserved as before.
_Prop., &c._ It is volatile at a dull red heat; excessively greedy of
moisture; and very soluble, with decomposition, hydrochloric acid and
alumina being formed. Once dissolved, it cannot be again recovered. Its
chief use is in the preparation of aluminum.
_Obs._ Although alumina, like magnesia, is freely soluble in hydrochloric
acid, the sesquichloride of aluminum contained in this solution cannot be
obtained in the anhydrous state, or even the solid form, by its
evaporation; the chloride suffering decomposition, with the formation of
hydrochloric acid, which is volatilised, and alumina, which is left
behind.
=Aluminum, Ni'trate of.= Al_{2}(NO_{3})_{6}. _Syn._ NITRATE OF ALUMINA;
ALU'MINÆ NI'TRAS, L. _Prep._ Similar to that of the acetate and citrate.
Its concentrated acid solution deposits rhombic crystals, containing 18
equiv. of water.
=Aluminum, Oxide of= (Al_{2}O_{3}), and =Hydrate of= (Al_{2}(HO)_{6}).
_Syn._ ALUMINA.
_Prep._ Aluminum is precipitated as a hydrate from solutions of aluminum
salts on the addition of an alkali or alkaline carbonate; and this
precipitate, after being thoroughly washed and dried, on ignition loses
its water and becomes anhydrous. The following are the best formulæ for
the purpose:--
Alum is dissolved in about 20 times its weight of distilled water, and the
solution is dropped slowly into pure solution of ammonia, until the latter
is nearly but not entirely saturated, when the whole is set aside for some
time. The clear supernatant liquid is then decanted, and the precipitate
is carefully and thoroughly washed three or four times with tepid
distilled water; after which it is collected on a filter, again well
washed with water, and, lastly, pressed and dried between bibulous paper,
either without heat, or at a temperature not higher than 120° Fahr. The
product is pure hydrate of ammonium, and is converted into anhydrous
alumina by exposure to a white heat in a covered crucible. The residuum,
after ignition, is pure ANHY'DROUS ALUMINA, or SESQUIOX'IDE OF ALUMIN'UM.
A solution of alum is slowly added to a solution of carbonate of ammonia,
avoiding excess; and the resulting precipitate, after being washed and
pressed, is dried at a heat of from 120° to 180° Fahr.
_Prop., &c._ A soft white powder. The hydrate is freely soluble in the
acids and in solution of caustic potassa and soda (from which it is
precipitable by sal ammoniac); when anhydrous (as after ignition), it is
scarcely acted on by acids, and when perfectly indurated, or crystallised,
it is wholly insoluble; but on ignition with alkalies, alkaline
ALU'MINATES are formed, and the alumina is then readily dissolved by
acids, forming salts, which are mostly colourless, non-volatile, and
soluble; they have a very astringent and somewhat sweetish taste, redden
litmus paper, and lose their acids by ignition. Its most remarkable, or
rather useful property, is its strong affinity for the fibres of organic
bodies, as cotton, flax, silk, wool, &c., which are capable of taking it
from its salts; and also for organic colouring matters. Hence its great
use in dyeing, and in bleaching liquids and the preparation of lakes.
Hydrate of aluminum agitated or digested with liquids containing vegetable
colouring matter, combines with the latter, and either entirely, or to a
great extent, removes it from the solution.
Moist precipitated alumina, dried at a heat between 70° and 80°, contains
above 58% of water; dried at 212° Fahr., about 32% of water.
_Estim._ Aluminum is weighed as oxide, after ignition. The solubility of
the moist or recently precipitated hydrate in solution of ammonia enable
us to separate it from the ALKALINE EARTHS which, when present, are thrown
down with it.
_Uses, &c._ The moist hydrate is used in several processes in the arts. It
is the base of cobalt-blue, the lake-pigments, &c. In _medicine_, it is
employed as an antacid and astringent, in acidity of the stomach, cholera,
diarrh[oe]a, and dysentery; in which it is said to be superior to the
other absorbent remedies. (Ficinus.) It has also been highly recommended
in the vomiting and diarrh[oe]a of infancy. (Durr; Neumann; Weese;
&c.)--_Dose._ Children 3 to 10 gr.; adults, 5 or 6 to 20 or even 30 gr.,
three to six times daily, suspended in water, by mucilage or simple syrup.
=Aluminum, Sil'icate of.= Al_{2}(SiO_{2})_{3}. _Syn._ SIL'ICATE OF
ALUMINA. A substance which, in its hydrous form, is the chief and
characteristic ingredient of common clay; and which also occurs, in
combination, in several other important and abundant minerals.
=Aluminum, Sul'phate of.= Al_{2}(SO_{4})_{3}. _Syn._ SESQUISUL'PHATE OF
ALUMINA, NEUTRAL S. OF A., ALU'MINÆ SUL'PHAS, A. SESQUISUL'PHAS, L.
_Prep._ 1. Saturate dilute sulphuric acid with hydrate of aluminum, gently
evaporate, and crystallise.
2. (Crude, commercial.) By mixing clay and oil of vitriol, in the way
described under ALUM. The product is the 'CONCENTRATED ALUM' of the dyers.
_Prop._ Its crystals are needles and thin pearly plates; soluble in 2
parts of water; taste astringent, and somewhat sweetish; reaction acid; a
full red heat expels its acid, leaving a residuum of pure alumina; with
the sulphates of potassium, sodium, and ammonium, it forms alum.
_Uses, &c._ In the _arts_, chiefly as a substitute for alum; the sulphate
of potassium in the latter, being found to be an unnecessary and costly
ingredient, only useful to purify the salt from iron, by forming a
compound of easy crystallisation; an object that may be effected with
greater certainty by cheaper methods. In _medicine_, as a wash for foul
and ill-conditioned ulcers; and as an astringent and antiseptic injection.
M. Gannal has successfully employed a solution of this salt to preserve
animal bodies, by throwing it into the arteries. Even an enema of 1 quart
of it, or an injection of a like quantity into the [oe]sophagus, will
suffice to preserve a body for several weeks. The mineral called AL'UNITE
or ALU'MINITE, found near Newhaven (Sussex), is a native subsulphate or
basic sulphate (DISUL'PHATE) of alumina.
=Aluminum, Sulphide of.= Al_{2}S_{3}. _Syn._ SUL'PHIDE OF ALUMINIUM, &c. A
substance best obtained by passing the vapour of bisulphide of carbon over
pure alumina, at a bright red heat. It is instantly decomposed by water,
with the evolution of sulphuretted hydrogen. See ALUMINUM (_above_).
=Aluminum Tann'ate.= _Syn._ TANNATE OF ALUMINA, Eng.; ALU'MINÆ TANN'AS, L.
_Prep._ Take of pure hydrate of aluminum (dried at 90° Fahr.), 1 part;
tannic acid (dried at 212°), 2 parts; triturate them together for some
time, adding just sufficient water to bring them to the consistence of a
syrup, and carefully evaporate to dryness at a heat not higher than 120°
Fahr.; lastly, reduce the residuum to powder.
_Uses, &c._ A combination of certain constitution, which is said to have
been found very useful in obstinate vomiting and diarrh[oe]a, in
dysentery, and particularly in hæmoptysis, hæmorrhage, &c.--_Dose_, 3 to
12 or 15 gr.
=Aluminium Bronze.= See BRONZE ALUMINIUM.
=AL'VINE= (-v[)i]n). _Syn._ ALVI'NUS, L.: ALVIN, Fr. Of or from the belly
or intestines; relating to the intestinal secretions.
=AMABELE.= Consists of crushed millets. See MILLET.
=AM'ADOU= (-[)a]h-d[=o][=o]). _Syn._ GERMAN TINDER, TOUCH'WOOD,
PYROTECH'NIC SPONGE, SPUNK[double-dagger]§, SURGEON'S AG'ARIC, A. OF THE
OAK, &c.; AGAR'ICUS QUER'CÛS, A. QUER'NUS, A. CHIRURGO''RUM, FUN'GUS
QUER'CÛS, &c., L.; AMADOU, AGARIC AMADOUVIER, Fr.; ZUNDERSCHWAMM. Ger. A
soft, spongy, combustible substance, being the prepared flesh of _bole'tus
fomenta''rius_ (Linn.), an indigenous species of fungus found on the oak,
birch, and a few other trees (REAL AMADOU or OAK-AGARIC); for which _b.
ignia''rius_ (Linn.), a like fungus, found on the willow, cherry, plum,
and other trees, is frequently substituted.
_Collec., Prep., &c._ The outer bark of the fungus (collected in Aug. or
Sept.) having been removed with a knife, the inner spongy substance is
carefully separated from the woody portion lying below, and after being
cut into slices, is well beaten with a mallet until sufficiently soft and
pliable. Sometimes it is first boiled in water, in order to separate the
epidermis and porous parts, and to free it from soluble matter; after
which it is beaten as before. In this state it is used in _surgery_, &c.
To complete its manufacture for TINDER, it is soaked once, or oftener, in
a strong solution of saltpetre (RED AMADOU; BROWN A.); or in a thin paste
made of gunpowder and water, which is thoroughly forced into the pores
(BLACK A.); after which it is dried, and well rubbed to free it from loose
matter. The first is the more cleanly; the last the more combustible.
_Uses, &c._ A light brown or reddish-brown substance. In _surgery_,
_pharmacy_, &c., it is used to stop local bleeding, to spread plasters on,
as a compress, and for other like purposes. When covered with
resin-plaster it forms an excellent article for the protection of abraded
surfaces. A small piece thus prepared, of a circular shape, having a round
hole cut in the middle, the size of the apex of the corn, is one of the
very best corn-plasters known; as from its great softness it at once
protects the part from pressure, and removes the cause. As a material for
shoe-socks it is superior to all other substances. The amadou for surgical
purposes must not contain nitre.
=AMAL'GAM.= [Eng., Ger.] _Syn._ AMAL'GAMA, L.; AMALGAME, Fr. In
_chemistry_ and _metallurgy_, an alloy containing quicksilver; more
particularly one in which that metal plays a conspicuous part. Medallists
improperly apply this term to all soft alloys.
Mercury unites with many of the metals by mere contact; and with some of
them, as gold, silver, tin, and lead, in certain proportions, without
losing its fluidity. In a few cases, as with potassium, this union is
attended with considerable violence, and with the production of light and
heat.
_Prep._ Most of these compounds may be formed by agitating or rubbing the
mercury with the other metal, or metals, in the state of filings or small
fragments, either with or without heat; or with the easily fusible metals,
by adding it to them in the melted state; care been taken, in both cases,
that the heat be not sufficient to volatilise the mercury.
_Prop., Uses, &c._ Some amalgams are solid, and not unfrequently
crystalline; others are fluid. Of the latter several crystallise after a
time, becoming solid; being, probably, merely solutions of the solid
amalgams in excess of mercury. The amalgams of gold, silver, tin, zinc,
&c., are extensively employed in gilding, silvering and dentistry, and in
other useful arts and manufactures.
=Amalgam, Ammonium.= An unstable compound produced when a globule of
mercury is placed in a small cavity formed in a piece of sal ammoniac, and
the negative pole of a powerful galvanic battery is brought into contact
with the metal, and the positive pole, with the ammoniacal salt. In a few
seconds the new compound (ammonium amalgam) of the consistence of butter
is formed. On withdrawing the influence of the battery, the whole returns
to its former condition. By putting an amalgam of sodium into the
moistened cavity of the sal ammoniac, similar results are obtained. The
phenomena attending the formation of this new substance have been urged as
evidence of the existence of the theoretical basic radicle AMMONIUM.
=Amalgam, Elec'trical.= _Prep._ 1. Take zinc and grain-tin, of each, 1
_oz._; melt them in an iron ladle, remove it from the fire, and add of
mercury (hot), 3 _oz._; stir the whole well together with an iron rod,
pour it into a well-chalked wooden box, and agitate it violently until
cold; or, instead of this, it may be briskly stirred until cold, and then
powdered. It should be preserved in a corked glass bottle.
2. (La Baumé.) Zinc, 2 _oz._; grain-tin, 1 _oz._; bees' wax, 1/2 _oz._;
melt, add of mercury, 6 _oz._, and otherwise proceed as before. Preferred
by some to all other mixtures.