Bisulphate of Potass, or Sal Enixum. - This is the salt mentioned above, as the residue from the process for obtaining nitric acid. It is employed, in very large quantities, in the manufacture of alum; also in tinning iron, for pickling, as it is termed; it is sometimes also used as a flux.

Nitrate of Potash, Nitre, or Saltpetre. This salt, which is of so much importance in every branch of the arts, is found native in many parts of the world, especially in the East Indies. It is obtained from soils composed of decomposing granite, the felspar of which gives rise, as is supposed, to the potass. The nitric acid is not so easily accounted for, except it is by a union of the nitrogen and oxygen gases in the atmosphere taking place in those hot climates; for, from authenticated accounts, no decaying animal or vegetable matter exists in the nitre districts of India. By lixiviation with water the nitre is dissolved from the soil, which is again thrown out into the air, to be washed the following year; so that it is formed continually. These lixiviations are then evaporated; and when of a certain strength, a quantity of common salt separates, which is removed as it falls; and the nitre is then crystallised and imported to this country, always containing a certain quantity of impurities, which are deducted in the purchase of large quantities of the article, being termed its refraction. It is generally used for the manufacture of gunpowder and pure nitric acid, refined or re-crystallised.

Nitre may be also made artificially, in beds of decaying vegetable or animal substances, mixed with old mortar, or other refuse calcareous earth; these are watered occasionally, too much moisture being hurtful; after a certain period, depending on the rapidity with which the process has gone on, the whole is submitted to lixiviation together with wood-ashes, which contain subcarbonate of potass, and which decomposes any nitrate of lime formed, of which there is generally a considerable quantity. After the lixiviation is complete, which takes some time, the solution is separated and boiled down; the salt separates as in the other process, and the nitre is then crystallised. It was from this source that the whole of the nitre, nearly, employed by the French during the long protracted war with the continental powers was obtained.

Nitre has a cold, penetrating, and nauseous taste; enters into igneous fusion at a gentle heat, and is then moulded into round cakes called sal prunella. It is employed in the manufacture of nitric acid; of gunpowder, which is composed of 75 parts by weight of nitre, 16 of charcoal, and 9 of sulphur (the nitre for this purpose should be of great purity); and in the manufacture of oil of vitriol: as a flux it is one of the most powerful we possess; it is also used for the preservation of animal food, and in making fri. gorific mixtures: 1 oz. of nitre dissolved in 5 oz. of water lowers its temperature 15 degrees of Fahrenheit's thermometer. (See SALTPETRE.)

Oralate and Binoxalate of Potass.-The binoxalate of potass, or salt of lemon, or sorrel, by both which last names it is very commonly known, is procured from the juice of the common sorrel (Rumex Acetosa), or the wood sorrel (Oxalis Acetosella), by crystallisation, after the feculent matter has been separated by standing a few days. Its chief uses are, in removing ink spots or iron moulds; and also as a refrestung beverage when mixed with sugar and water.

The neutral oxalate is obtained from this salt by combining the excess of acid which it contains with a solution of subcarbonate of potass. Is very much used in chemistry, as the best test of the presence of lime.

Tartrate and Bitartrate of Potass. - Bitartrate of potass, or cream of tartar, is, when in its crude and impure state, called argol, and is deposited in the interior of wine casks during fermentation, and from this source the whole of the cream of tartar is obtained. It is generally of a very dark brown colour, but may be purified and rendered perfectly white by solution and crystallisation. It is employed very extensively in dyeing, hat-making, and in the preparation of tartaric acid, and many of the compounds of tartaric acid, as tartar emetic, soluble tartar (tartrate of potass): when heated to redness it is converted into carbonate of potass and charcoal; mixed with half its weight of nitre and thrown into a red hot crucible it forms the black flux, and with its own weight of nitre the white flux, both of which are very much employed in metallurgic operations. The tartrate is made by the addition of subcarbonate of potass to a solution of the bitartrate until perfectly neutral: it is used in medicine as a mild purgative. Ferrocyanate or Prussiate of Potass. This salt is obtained by the action of subcarbonate of potass, at a low red heat, upon refuse animal matter, such as hoofs, horns, skin, &c., in the proportion of two of subcarbonate to four or five of the animal matter. But the process recommended by M. Gautier is preferable; he finds, that when animal matter is heated with nitre, it yields a much larger quantity of the ferroprussiate than when either potass or subcarbonate of potass are employed; the proportions he finds most economical are, 1 part by weight of nitre, 3 parts of dry blood, and iron scales or filings equal to a fiftieth of the blood employed."

The coagulum of blood is mixed intimately with the nitre and iron filings, and dried by exposure to the air; they are then submitted to a very low red heat, in deep iron cylinders, as long as vapours continue to be liberated; when cold, the contents are dissolved in 12 or 15 times their weight and strained. On evaporation till of the specific gravity 1-284, and allowing it to cool, a large quantity of bicarbonate of potass crystallises, and by further evaporation till of the specific gravity 1306, the ferroprussiate of potass crystallises on cooling. This is to be recrystallised. It is a beautiful yellow salt, very tough, having a tenacity similar to spermaceti, and is decomposed at a red heat. It is employed very extensively in dyeing blues, and in calico printing; also in the manufacture of Prussian blue, which is a compound of the ferroprussic acid and oxide of iron, prepared by adding 1 part of the ferroprussiate of potass dissolved in water, to 1 part of copperas, and 4 parts of alum in solution.

Chromate of Potass. This salt is obtained from the native chromate of iron by the action of nitre at a full red heat in equal proportions. By solution, filtration, and evaporation, a beautiful lemon-yellow coloured salt results. It is very much employed in dyeing, calico printing, and calico making, from its producing bright yellow precipitates with solutions of lead.

Bichromate of Potassis prepared from the above-mentioned salt, by the addition of nitric acid to the yellow solution obtained from the heated mass by the action of water; on evaporating this, a dark red coloured salt crystallises, which is the bichromate. This is also very largely employed by the calico printers, and when mixed in solution with nitric acid, possesses the property of destroying vegetable colours; on this account it is of great importance, as it at the same time removes a vegetable colour, and forms a base for a yellow dye.

Chlorate or Hyperoxymuriate of Potass. The preparation of this salt is attended with some little difficulty, and requires a great deal of nicety. It is obtained by passing a current of chlorine gas through a solution of caustic potass; then boiling and evaporating; the first salt that separates is the chlorate of potass; and by further evaporation, muriate of potass is obtained. It is used in making matches for instantaneous light boxes, which are prepared by first dipping the wood in melted sulphur, and then into a thin paste, formed of 3 parts chlorate of potass, 2 parts starch, and a little vermilion; with sulphur it forms a very explosive compound, generally employed for filling the pereussion caps of fowling-pieces. Soda, or Mineral Alkali. — The sources of this alkali in nature are various. It is obtained in combination with carbonic acid, when plants which grow by the sea-side are burnt. The ashes thus obtained are called barilla and kelp; and also in some countries it is found as an efflorescence upon the surface of the earth, and is called nitrum or natron; this occurs particularly in Egypt and South America. Trona is also another native carbonate of soda, and is exported from Tripoli. In combination with muriatic acid it is also found in immense abundance, forming the rock salt, and sea salt or muriate of soda. It is obtained from the carbonate exactly in the same way as potass is obtained from its carbonate, namely, by boiling it with fresh burnt lime previously slaked, decanting the clear solution, and evaporating and fusing. It is a white brittle substance, and by exposure to the air becomes converted into a dry carboIts uses in the arts and manufactures are of considerable importance. In soap-making it is

nate.

1

28

ALKANET. — ALLOWANCES.

employed in very large quantities, and for this purpose is generally procured from barilla or kelp, by mixing them with lime, and by the infusion of water procuring a caustic soda ley; this is mixed with oil and fatty matters in various proportions, and boiled; the saponification of the fatty matter takes place, and the soap formed rises to the surface; the ley is then drawn from beneath, and fresh leys added, until the soap is completely free from oil; it is then allowed to dry. Soda is also employed in the mangfacture of plate, crown, and bottle glass, though for this purpose it is generally in the form of carbonate or sulphate.

Subcarbonate of Soda. (In the chemical nomenclature it is called carbonate.) — This is generally prepared from barilla, which contains about from 16 to 24 per cent. Barilla is procured by incinerating the salsola soda, and other sea-side plants; it is made in large quantities on the coast of Spain. Kelp is another impure carbonate of soda, but does not contain more than 4 or 5 per cent., it is the ashes obtained from gea weeds by incineration, and is made on the northern shores of Scotland. From these, the crystallised carbonate (or subcarbonate, as it is more frequently called) is made by the addition of a small quantity of water, boiling, straining, evaporating, and skimming off the common salt as it forms on the surface; on cooling, the subcarbonate of soda crystallises. Another method is by heating the sulphate of coda with carbonate of lime and charcoal, and then dissolving out the soluble carbonate, also, by the action of carbonate of potass (pearlash) upon solutions of sea salt. - (See BARILLA and KELP.)

Bicarbonate of Soda-is procured by driving a current of carbonic acid gas through solutions of the carbonate, and then evaporating at a temperature below 212 Fahrenheit; it is chiefly employed in making soda water powders. This is the carbonate of soda of the Pharmacopoeia. By the application of a red heat it loses carbonic acid, and is converted into the subcarbonate.

Sulphate of Soda, or Glauber Salts. This salt, which has received the name of Glauber, from its discoverer, is the residue of a great many chemical processes; for instance, when muriate of soda is acted upon by oil of vitriol, muriatic acid and sulphate of soda result; in making chlorine gas for the manufacture of the chloride of lime, or bleaching powder, sulphate of sda and sulphate of mangincse result; the materials employed being sea salt, sulphuric acid (oil of vitriol), and black oxide of manganese: also, in the preparation of acetic acid from the acetate of soda, and in the preparation of muriate of ammonia from sea salt and sulphate of ammonia. Sulphate of soda is a colourless, transparent salt, effloresces readily when exposed to the air, and becomes converted into a dry powder; it has a cold, bitter taste. It is used for the preparation of carbonate of soda, and as a medicine. It is found native in some countries, particularly in Persia and South America-frequently as an florescence upon new walls. Nitrate of Soda. This salt is found native in some parts of the East Indies, and is called, from its square form, cubic nitre; it is, however, very little used.

Muriate of Soda, or Sea Salt. This compound is found in immense quantities in the earth, and is called from this circumstance rock salt, or sal gem. The mines of Cheshire and Droitwich, in this country, and those in Poland, Hungary, and Spain, and many others, afford immense quantities of this compound. It is also obtained by the evaporation of sea water, both spontaneously in pits formed for the purpose, and in large iron boilers; the uncrystallisable fluid is called the bittern; basket salt is made by placing the salt after evaporation in conical baskets, and passing through it a saturated solution of salt, which dissolves and carries off the muriate of magnesia or lime. Pure salt should not become moist by exposure to the air; it decrepitates when heated; it is employed for the preparation of muriatic acid, carbonate of soda, muriate of ammonia, and many other operations; also in glazing stone-ware, pottery, &c.; and from its great antiseptic properties, is used largely for the preservation of animal food; as a flux also in metallurgy.

Borate of Soda, or Borar. This salt is found in Thibet and Persia, deposited from saline lakes; it is called tincal, and is imported into this country, where it is purified by solution; the fatty matter with which the tincal is always coated being removed, and the solution evaporated and crystallised; its principal uses are as a flux, from its acting very powerfully upon earthy substances.

ALKANET, or ANCHUSA (Ger. Orkanet; Du. Ossetong; Fr. Orcanette; It. Ancusa; Sp. Arcaneta), a species of bugloss ( Anchusa tinctoria Lin). It has been cultivated in England; but is found of the finest quality in Siberia, Spain, and more particularly in the South of France, in the vicinity of Montpelier. The roots of the plant are the only parts that are made use of. When in perfection, they are about the thickness of the finger, having a thick bark of a deep purplish red colour. This, when separated from the whitish woody pith, imparts a fine deep red to alcohol, oils, wax, and all unctuous substances. To water it gives only a, dull brownish hue. It is principally employed to tint wax, pomatum, and unguents, oils employed in the dressing of mahogany, rose-wood, &c. The alkanet brought from Constantinople yields a more beautiful but less permanent dye than that of France.-(Lewis's Mat. Med. ; Magniem, Dictionnaire des Productions.)

The duty, which was previously very oppressive, was reduced in 1832 to 28. a cwt.; and by the tariff of last year (1842) to Is. a cwt. The imports are inconsiderable. The price varies from 27s. to 3.s. a cwt. ALLOWANCES, TARES, &c. In selling goods, or in paying duties upon them, certain deductions are made from their weights, depending on the nature of the packages in which they are inclosed, and which are regulated in most instances by the custom of merchants, and the rules laid down by public offices. These allowances, as they are termed, are distinguished by the epithets Draft, Tare, Tret, and Cloff.

Draft is a deduction from the original or gross weight of goods, and is subtracted before the tare is taken off.

Tare is an allowance for the weight of the bag, box, cask, or other package, in which goods are weighed.
Real or open tare is the actual weight of the package.

Customary tare is, as its name implies, an established allowance for the weight of the package.
Computed tare is an estimated allowance agreed upon at the time.

Average tare is when a few packages only among several are weighed, their mean or average taken,
and the rest tared accordingly."

Super-tare is an additional allowance, or tare, where the commodity or package exceeds a certain weight. When tare is allowed, the remainder is called the nett weight; but if trett be allowed, it is called the suttle weight.

Trett is a deduction of 4 lbs. from every 104 lbs. of suttle weight.

This allowance, which is said to be for dust or sand, or for the waste or wear of the commodity, was formerly made on most foreign articles sold by the pound avoirdupois; but it is now nearly discontinued by merchants, or else allowed in the price. It is wholly abolished at the East India warehouses in London; and neither trett nor draft is allowed at the Custom-house.

Claff, or Clough, is another allowance that is nearly obsolete. It is stated in arithmetical books to be a deduction of 2 lbs. from every 3 cwt. of the second suitle; that is, the remainder after trett is subtracted;

but merchants, at present, know cloff only as a small deduction, like draft, from the original weight, and this only from two or three articles.-(See Kelly's Cambist, art. "London.")

For an account of the tares and allowances at London, see TARE; for the tares and allowances at the great foreign trading towns, see their names.

ALMONDS (Ger. Mandeln; Du. Amandelen; Fr. Amandes; It. Mandorli; Sp. Almendra; Port. Amendo; Rus. Mindal; Lat. Amygdala amare, dulces), a kind of medicinal fruit, contained in a hard shell, that is enclosed in a tough sort of cotton skin. The tree (Amygdalus communis) which produces this fruit nearly resembles the peach both in leaves and blossoms; it grows spontaneously only in warm countries, as Spain, and particularly Barbary. It flowers early in the spring, and produces fruit in August. Almonds are of two sorts, sweet and bitter. They are not distinguishable from each other but by the taste of the kernel or fruit. "The Valentia almond is sweet, large, and flat-pointed at one extremity, and compressed in the middle. The Italian almonds are not so sweet, smaller, and less depressed in the middle. The Jordan almonds come from Malaga, and are the best sweet almonds brought to England. They are longer, flatter, less pointed at one end and less round at the other, and have a paler cuticle than those we have described. The sweet almonds are imported in mats, casks, and boxes; the bitter arrive in boxes."-(Thomson's Dispensatory.)

Previously to 1832 almonds were grossly overtaxed; but the duties were then considerably reduced, and they were also still further reduced in 1842 and 1853. The duty on all varieties (inc. Jordan) of sweet aimonds was fixed in the last mentioned year at 10s. a cwt., that on bitter almonds having been previously repealed. The imports of sweet and bitter almonds respectively amounted in 1853 to 21.723 and 6,352 cwts.; the bitter being almost entirely supplied by Morocco, which also supplied by far the larger portion, or 15.974 cwt., of the sweet, the residue of the latter being brought, 3,844 cwt. from Spain. 879 do. from France, 347 do. from Portugal, and 699 do. from other parts. During the same year 10,143 cw'. sweet almonds were entered for consumption, whereof 4,482 cwt. were of Morocco, 4,307 do. Spanish, 778 do. French, &c. The Morocco almonds are mostly shipped at MOGADORE, which see.

ALOES (Du. Aloe; Fr. Aloés; Ger. and Lat. Aloe; Rus. Subir; Sp. Aloè; Arab. Mucibar), a bitter, gummy, resinous, inspissated juice, obtained from the leaves of the plant of the same name. There are four sorts of aloes met with in commerce; viz. Socotrine, Hepatic, Caballine, and Cape.

1. Socotrine-so called from the island of Socotra, in the Indian Ocean, not very distant from Cape Guardafui, where the plant (Aloe spicata), of which this species is the produce, grows abundantly. It is in pieces of a reddish brown colour, glossy as if varnished, and in some degree pellucid. When reduced to powder, it is of a bright golden colour. Its taste is extremely bitter; and it has a peculiar aromatic odour, not unlike that of the russet apple decaying. It softens in the hand, and is adhesive: and yet is sufficiently pulverulent. It is imported by way of Smyrna and Alexandria, in chests and casks, but is very scarce in England.

2. Hepatic The real hepatic aloes, so called from its liver colour, is believed to be the produce of the Aloe perfoliata, which grows in Yemen in Arabia, from which it is exported to Bombay, whence it finds its way to Europe. It is duller in the colour, bitterer, and has a less pleasant aroma than the Socotrine aloes, for which, however, it is sometimes substituted. Barbadoes aloes, which is often passed off for the hepatic, is the produce of the Aloe vulgaris. It is brought home in calabashes, or large gourd shells, containing from 60 to 70 lbs. It is duskier in its hue than the Bombay, or real hepatic aloes, and the taste is more nauseous, and intensely bitter. The colour of the powder is a dull olive yellow.

3. Caballine or Horse Aloes seems to be merely the coarsest species or refuse of the Barbadoes aloes. It is used only in veterinary medicine; and is easily distinguished by its rank fœtid smell.

4. Cape Aloes is the produce of the Aloe spicata, which is found in great abundance in the interior of the Cape colony, and in Melinda. The latter furnishes the greater part of the extract sold in Europe under the name of Socotrine aloes. The odour of the Cape aloes is stronger and more disagreeable than that of the Socotrine; they have, also, a yellower hue on the outside; are less glossy, softer, and more pliable; the colour of the powder is more like that of gamboge than that of the true Socotrine aloes.Ainslie's Mat. Indica; Thomson's Dispensatory and Mat. Medica.)

Of 246,575 lbs. aloes imported in 1853, from 190,000 to 200,000 lbs. were probably taken for consumption. Duties repealed in 1845.

ALOES-WOOD (Ger. Alocholz; Du. Aloëhout, Paradyshout; Fr. Bois d' Aloés; It. Legno di Aloe; Sp. Aloè chino; Lat. Lignum Aloes; Sans. Aguru; Malay, Agila; Siam. Kisna), the produce of a large forest tree, to be found in most of the countries between China and India, from the 24th degree of north latitude to the equator.

It seems to be the result of a diseased action confined to a small part of a few trees, of which the rest of the wood is wholly valueless. It appears to be more or less frequent according to soil and climate, and from the same causes to differ materially in quality. It is produced both in the greatest quantity and perfection in the countries and islands of the east coast of the Gulf of Siam. This article is in high repute for fumigations, and as incense, in all Hindu, Mohammedan, and Catholic countries. It formerly brought a very high price, being at one time reckoned nearly as valuable as gold. It is now comparatively cheap, though the finest specimens are still very dear. The accounts of this article in most books, even of good authority, are singularly contradictory and inaccurate. This is more surprising, as La Loubère has distinctly stated, that it consisted only of "certains endroits corrumpus dans des arbres d'une certaine espèce. Toute arbre de cette espèce n'en a pas; et ceux qui en ont, ne les ont pas tous en même endroit." (Royaume de Siam, t. i. p. 45. 12mo. ed.) The difficulty of finding the trees which happen to be diseased, and of getting at the diseased portion, has given rise to the fables that have been current as to its origin. The late Dr. Roxburgh introduced the tree which yields this production into the Botanical Garden at Calcutta, from the hills to the eastward of Sylhet, and described it under the name of Aquillaria Agalocha.

ALUM (Ger. Alaun; Du. Aluin; Fr. Alun; It. Allume; Sp. Allumbre; Rus. Kwasszë; Lat. Alumen; Arab. Sheb), a salt of great importance in the arts, consisting of a ternary compound of aluminum, or pure argillaceous earth, potass, and sulphuric acid. Alum is sometimes found native; but by far the greater part of that which is met with in commerce is artificially prepared. The best alum is the Roman, or that which is manufactured near Civita Vecchia, in the Papal territory. It is in irregular,

octahedral, crystalline masses, about the size of a walnut, and is opaque, being covered on the surface with a farinaceous efflorescence. The Levant, or Roch alum, is in fragments, about the size of the former, but in which the chrystalline form is more obscure; it is externally of a dirty rose-colour, and internally exhibits the same tinge, but clearer. It is usually shipped for Europe from Sinyrna; but it was anciently made at Roccha, or Edessa, in Syria; and hence its name Roch alum. English alum is in large, irregular, semi-transparent, colourless masses, having a glassy fracture; not efflorescent, and considerably harder than the others. It is very inferior to either the Roman or Roch alum. The principal use of alum is in the art of dyeing, as a mordant for fixing and giving permanency to colours which otherwise would not adhere at all, or but for a very short time; but it is also used for a great variety of other purposes. Beckmann has shown (History of Inventions, vol. L. art. “ Alum ") that the ancients were unacquainted with alum, and that the substance which they designated as such was merely vitriolic earth. It was first discovered by the Orientals, who established alum works in Syria in the thirteenth or fourteenth century. The oldest alum works in Europe were erected about the middle of the fifteenth century. Towards the conclusion of the reign of Queen Elizabeth, Sir Thomas Chaloner established the first alum work in England, in the vicinity of Whitby, in Yorkshire, where the principal works of the sort in this country are still carried on; the shipments of alum from Whitby in 1841 amounted to 3,237 tons. There is, also, a large alum work at Hurlett, near Paisley, the produce of which may be estimated at about 1,200 tons a year. Alum is largely manufactured in China, and is thence exported to all the western Asiatic countries. In 1837, 35,642 piculs (2,120 tons) were exported from Canton.

AMBER (Ger. Bernstein; Du. Barnsteen; Da. Bernsteen, Rav.; Fr. Ambre jaune; It. Ambra gialla, Sp. Ambar; Rus. Jantar; Pol. Bursztyn; Lat. Succinum, Electrum), a brittle, light, hard substance, usually nearly transparent, sometimes nearly colourless, but commonly yellow, or even deep brown. It has considerable lustre. Specific gravity 1065. It is found in nodules or rounded masses, varying from the size of coarse sand to that of a man's hand. It is tasteless, without smell, except when pounded or heated, when it emits a fragrant odour. It is highly electric. Most authors assert that amber is bituminous; but Dr. Thomson states, that "it is undoubtedly of a vegetable origin; and though it differs from resins in some of its properties, yet it agrees with them in so many others, that it may without impropriety be referred to them."-(Chemistry, vol. iv. p. 147. 5th ed.)

Pieces of amber occasionally enclose parts of toads and insects in their substance, which are beautifully preserved. It is principally found on the shores of Pomerania and Polish Prussia; but it is sometimes dug out of the earth in Ducal Prussia. It is also met with on the banks of the river Giaretta, in Sicily. Sometimes it is found on the east coast of Britain, and in gravel pits round London. The largest mass of amber ever found was got near the surface of the ground in Lithuania. It weighs 18 lbs., and is preserved in the royal cabinet at Berlin. Most of the amber imported into this country comes from the Baltic, but a small quantity comes from Sicily. Amber was in very high estimation among the ancients, but is now comparatively neglected.

AMBER-GRIS, OR AMBER-GREASE (Ger. Amber; Du. Amber; Fr. Ambergris; It. Ambra-grigia; Sp. Ambar-gris; Lat. Ambra, Ambra grisea,) a solid, opaque, generally ash-coloured, fatty, inflammable substance, variegated like marble, remarkably light, rugged and uneven in its surface, and has a fragrant odour when heated; it does not effervesce with acids, melts freely over the fire into a kind of yellow resin, and is hardly soluble in spirit of wine. It is found on the sea-coast, or floating on the sea, near the coasts of India, Africa, and Brazil, usually in small pieces, but sometimes in masses of 50 or 100lbs. weight. "Various opinions have been entertained respecting its origin. Some affirmed that it was the concrete juice of a tree, others thought it a bitumen; but it is now considered as pretty well established that it is a concretion formed in the stomach or intestines of the Physeter macrocephalus, or spermaceti whale." -(Thomson's Chemistry.) Ambergris ought to be chosen in large pieces, of an agreeable odour, entirely grey on the outside, and grey with little black spots within. purchaser should be very cautious, as this article is easily counterfeited with gums and other drugs.

The

AMETHYST (Ger. Amethyst; Fr. Amethyste; It. Amatista; Sp. Ametisto; Lat. Amethystus), a precious stone, of which there are two species differing widely in quality and value.

The Oriental amethyst is a gem of the most perfect violet colour, and of extraordinary brilliancy and beauty. It is said to be as hard as the sapphire or ruby, with which it also corresponds in its form and specific gravity-(see SAPPHIRE), differing in colour merely. It has been met with in India, Persia, Siam, and other countries; but it is exceedingly scarce. That found in India is said by Pliny to be the best. (Principatum amethysti Indica tenent. Nat. Hist. lib. xxxvii. cap. 9.) Mr. Mawe says he had rarely seen an oriental amethyst offered for sale, unless small and inferior in colour. Mr. Hope, the author of Anastasius, had in his cabinet the finest gem of this sort in Europe. This exquisite specimen exceeds an inch in its greatest diameter; in daylight it exhibits the most beautiful violet colour, while by candlelight it is a decided blue.

The Occidental amethyst is merely coloured crystal or quartz." When perfect, its colour resembles that of the violet, or purple grape; but it not unfrequently happens that the tinge is confined to one part of the stone only, while the other is left almost colourless. When it possesses a richness, clearness, and uniformity of hue, it is considered a gem of exquisite beauty; and as it occurs of considerable size, it is suited to all ornamental purposes. In specific gravity and hardness it bears no comparison with the oriental amethyst; it is also inferior in beauty and lustre; though I have often seen the common amethyst offered for sale as oriental. Brazil, Siberia, and Ceylon produce very fine amethysts: they are found in rolled pieces in the alluvial soil, and finely crystallised in fissures of rock. From the first of these localities, they have lately been imported in such quantities as considerably to diminish their

மது"

value: but as they are the only coloured stones, except garnets, that are worn with mourning, they still retain, when perfect, a distinguished rank among the precious gems. The present price of inferior lightcoloured stones, in the rough state, is about 208. per pound, whilst those of good quality sell at 10s. or 12s. per ounce. Amethysts calculated for brooches or seals may be purchased at from 15s. to two or three guineas each, for which, ten years ago, treble that sum would have been given.”—(Mawe on Diamonds, 2d ed. pp. 115–117.)

AMIANTHUS, ASBESTOS, OR MOUNTAIN FLAX, a mineral of which there are several varieties, all more or less fibrous, flexile, and elastic. It is inconsumable by a high degree of heat; and in antiquity the art was discovered of drawing the fibres into threads, and then weaving them into cloth. Pliny says that he had seen napkins made of this substance, which, when soiled, were thrown into the fire, and that they were better cleaned by this means than they could have been by washing! Hence it obtained from the Greeks the name of Aavros (undefiled). Its principal use, as stated by Pliny, was to wrap the bodies of the dead previously to their being exposed on the funeral pile, that the ashes of the corpse might not be mixed with those of the wood. And in corroboration of this statement we may mention, that in 1702, a skull, some calcined bones, and a quantity of ashes, were found at Rome, in a cloth of amianthus nine Roman palms in length by seven in width. Its employment in this way was, however, confined to a few of the very richest families, incombustible cloth being very scarce, and bringing an enormously high price. Rarum inventu, difficile textu propter brevitatem. Cùm inventum est, æquat pretia excellentium margaritarum. (Plin. Hist. Nat. lib. xix. cap. 1.) The disuse of the practice of cremation, or of burning the dead, caused the manufacture of amianthine cloth to be neglected. Several moderns have, however, succeeded in making it; but, if it be not lost, the art is now rarely practised. (For further particulars, see Rees's Cyclopædia.)

AMMONIACUM (Fr. Gomme Ammoniaque; It. Gomma Ammoniaco; Sp. Goma Ammoniaco; Lat. Ammoniacum; Arab. Feshook), a concrete resinous juice obtained from a plant resembling fennel, found in the north of Africa, Arabia, Persia, the East Indies, &c. Pliny says that it derived its name from its being produced in the vicinity of the temple of Jupiter Ammon in Africa. —(Hist. Nat. lib. xii. cap. 23.) It has a faint but not ungrateful smell; and a bitter, nauseous, sweet taste. The fragments are yellow on the outside and white within, brittle, and break with a vitreous fracture; their specific gravity is 1.207. The best ammoniacum is brought from Persia by Bombay and Calcutta, packed in cases and chests. It is in large masses, composed of small round fragments or tears; or in separate dry tears, which is generally considered a sign of its goodness. The tears should be white internally and externally, and free from seeds or other foreign substances. Reject that which is soft, dark-coloured, and foul. It is used principally in the materia medica, and the quantity imported is but small. (Rees's Cyclopædia; Thomson's Dispensatory; Milburn's Orient. Com. &c.) AMMONIAC (SAL). See ALKALIES (Muriate of Ammonia).

AMMUNITION, a term expressive of the various implements used in war. No ammunition can be imported into the United Kingdom by way of merchandise, except by licence from his Majesty, for furnishing his Majesty's stores only, under penalty of forfeiture. -(3 & 4 Will. 4. cap. 52. § 58.) His Majesty may forbid, by order in council, the exportation of any saltpetre, gunpowder, or any sort of ammunition. Any master of a vessel exporting ammunition when so forbidden, shall for every such offence forfeit 100%.

(29 Geo. 2. c. 16.)

AMSTERDAM, the principal city of Holland, situated on the Y, an arm of the Zuyder Zee, in lat. 52° 22′ 17′′ N., long. 4° 53′ 15′′ E. From 1580 to 1750, Amsterdam was, perhaps, the first commercial city of Europe; and though her trade has experienced a great falling off since the last-mentioned epoch, it is still very considerable. In 1785, the population is said to have amounted to 235,000; in 1815 it had declined to 180,179; but its increase in the interval has been such, that it amounted in 1857 to 260,037. The harbour is spacious and the water deep; and it has recently been much improved by the construction of docks, two of which are already completed, and a third in a very advanced state. Owing, however, to a bank (the Pampus) where the Y joins the Zuyder Zee, large vessels going or coming by that sea are obliged to load and unload a part of their cargoes in the roads. The navigation of the Zuyder Zee is also, by reason of its numerous shallows, very intricate and difficult; and as there were no hopes of remedying this defect, it became necessary to resort to other means for improving the access to the port. Of the various plans suggested for this purpose, the preference was given to the scheme for cutting a canal capable of admitting the largest class of merchantmen, from the north side of the port of Amsterdam to Newdiep, opposite to the Texel, and a little to the east of the Helder. This canal has fully answered the views of the projectors, and has proved of signal service to Amsterdam, by enabling large ships to avoid the Pampus, as well as the difficult navigation of the Zuyder Zee, where they were frequently detained for three weeks, and to get to and from Newdiep without any sort of risk in less than 24 hours. The canal was begun