Chapter C: W. HEATON, F.I.C., F.C.S., Lecturer on Chemistry at the (11)

_Uses, &c._ The applications of alum in the arts and manufactures are numerous and important. It is used to harden tallow and fats; to render wood and paper incombustible; to remove greasiness from printers' blocks and rollers; to prepare a paper for whitening silver and silvering brass in the cold; to help the separation of the butter from milk; to purify turbid water; to dress skins; to fix and brighten the colours in dyeing; to make lake and pyrophorus, &c., &c. It is also extensively used for clarifying liquors, and for many other purposes connected with the arts and everyday life. In _medicine_, alum is used as a tonic and astringent, in doses of 5 to 20 gr.; as a gargle (1 dr. to 1/2 pint of water); and as a collyrium and injection (10 to 15 gr. to 6 oz. of water). In lead colic, 1/2 to 1 dr. of alum (dissolved in gum-water), every 3 or 4 hours, is said to be infallible. Powdered alum is frequently applied with the tips of the fingers, in cases of sore throat and ulcerations of the mouth, &c. A teaspoonful of it is said to be one of the very best emetics in croup. (Dr Meigs.) Alkalies, alkaline carbonates, lime, magnesia, acetate of lead, astringent vegetables, &c., are incompatible with it.

_Gen. commentary._ In addition to the particulars of its manufacture given above, we may add, that the plan of getting rid of the ferric salts there referred to has to some considerable extent been successfully replaced by that of precipitating the alum, instead of the sulphate of iron, by adding alkaline matter to the lixivium. The crystalline precipitate is purified by draining, re-solution, and re-crystallisation; whilst the sulphate of iron and Epsom-salts contained in the mother liquor are obtained by subsequent evaporation and crystallisation; after which a fresh crop of alum may be got from it, by the use of an alkaline precipitant, as before.

In estimating the strength of his solution the alum-maker takes as a standard a measure or sp. gr. bottle capable of holding exactly 80 pennyweights of distilled water. The excess of the weight of liquor, in pennyweights, over 80, or that of water, is called so many 'pennyweights strong.' Thus one of 90 pennyweights (90 dwt.) is said to be '10 dwt. strong,' or simply, 'one of 90 dwt.' These numbers correspond to 2-1/2 degrees of Twaddle's hydrometer, and may easily be found by dividing Twaddle's degrees by 2·5 or 2-1/2; or by multiplying them by 4, and pointing off the right-hand figure of the product for a decimal. The result is in alum-makers' pennyweights.

By a patent now expired (Weisman's, 1839) the ferric salts are precipitated by the addition of a solution of ferrocyanide of potassium (prussiate of potash); after which the supernatant clear liquor, which is now a solution of nearly pure sulphate of alumina, is decanted, and evaporated for future operations, until it either forms, on cooling, a concrete mass, which is moulded into bricks or lumps, for the convenience of 'packing,' or until it is sufficiently concentrated to be converted into ALUM by the addition of a salt of potash or of ammonia in the usual manner. The product, in each case, is perfectly free from iron. By a like addition of the ferrocyanide to a solution of ordinary sulphate of aluminia or alum, the dyer may himself easily render them free from iron, or iron-alum; when, as mordants for even the most delicate colours, they are equal to the very best Roman alum.

Another process has been patented (Barlow & Gore, 1851) for the manufacture of alum from the ash or residue of the combustion of Boghead-coal, which, though hitherto regarded as almost valueless, actually contains about 30% of alumina. It has not, however, been found a convenient material for the purpose.

By the latest and most approved processes the least possible quantity of boiling water or liquor is employed for making the solutions, so that they may crystallise without evaporation, and thus economise fuel; and the mother-liquors of previous operations are constantly employed for this purpose, when possible. Nor is anything which is convertible to use, from the drainage of the heaps, to the liquor and slime of the roaching casks, allowed to be wasted.

By whatever process, or from whatever materials alum is obtained, it is absolutely necessary for the successful and economical conduct of its manufacture, that the precise composition of the mineral or minerals employed should be exactly known. This can only be determined by actual analysis, which should be extended to several parts of the same bed, and particularly to the upper and lower strata, which frequently differ in composition from each other, and thus require different treatment, or may be most advantageously employed in combinations with each other. The necessity of this will be seen by reference to the composition of the following minerals, of which the top contains a larger proportion of iron-pyrites than the bottom, and the two require to be mixed, to equally diffuse the sulphuric acid generated by the calcination, &c., to which they are subjected.

The following is the per-centage composition of certain alum shales:--

+------------------+-------------------+
| | 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.

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.