It is more easily melted than the precious garnet.

"The garnet varies more than any other gem, both in the form of its crystals, and in its colour; some being of a deep red, some yellowish, or of a purple tint, and others brown, blackish, and quite opaque. They are generally of a spherical form, and never crystallize with less than twelve sides. The prevailing colour is a fine red, and the mean size that of a large pea, though they are found from the size of a grain of sand to three or four inches in diameter. Those imbedded in granite are in general of the smallest size, but at the same time the

most transparent. Among the garnets which are called Oriental may be distinguished three different shades, known in commerce by as many different names. The garnet of a fine red colour, and free from any mixture, is called a carbuncle. Garnets are found in almost every country where primitive rocks exist. Switzerland and Bohemia are the two countries in Europe which furnish them in the greatest abundance. Those of Bohemia have a tint of orange mixed with the red, from whence some have given them the name of rubies. These stones are likewise fouud in Hungary, at Pyrna in Silesia, in Spain, and in Norway. At Bareith, a town in Germany, garnets are found in little irregular masses of a fine red colour, and abundantly disseminated in a green semi-transparent stone called serpentine. As they are susceptible of a fine polish, the inhabitants form them into several pretty trinkets and other articles of jewelry. Black garnets are met with in different situations. Ramond, professor of natural history at Tarbes, collected some from a mountain of the Pyrenees in the neighbourhood of Barege; Rome de l'Isle

found them in the diamond mines of Brazil; and Brongniart tells us that they have been discovered in a volcanic rock near Vesuvius, and in the basaltes of Bohemia. When garnets are perfectly transparent, and hard enough to bear a fine polish, the lapidaries cut them into facits, to be employed as jewels. In Bohemia there are places where they work the garnets which are found in the neighbourhood. There are workshops also at Friburg, in Brisgaw, for the garnets which are collected from several of the Swiss mountains. The impure garnets are used to advantage as a flux, when they are found near iron-mines, as they not only facilitate the fusion of that metal, but add something to the mass, by contributing the por tion of iron which generally enters into their composition. The quantity indeed is sometimes so great, that they have been said to yield 4016. in the cwt. and consequently worth smelting alone for the sake of their produce." See Wood's "Zoography," to which we have been indebted in the articles COAL and FIcus.

GARNET, in a ship, is a tackle having a pendant coming down from the mainmast, with a block well seized to the main stay, just over the hatch-way, to which a guy is fixed to keep it steady; and at the other end is a long tackle

block, in which the fall is reeved, that so by it any goods may be hauled and hoisted into or out of the ship.

GARNISHEE, the party in whose hands money is attached, within the liberties of the city of London, so used in the Sheriff of London's court, because he has had garnishment, or warning, not to pay the money, but to appear and answer to the plaintiff creditor's suit.

GARNISHMENT, a warning given to one for his appearance for the better furnishing of the cause and court.

GARRISON, in the art of war, a body of forces, disposed in a fortress, to defend it against the enemy, or to keep the inhabitants in subjection; or even to be subsisted during the winter-season: hence, garrison and winter-quarters are sometimes used, indifferently, for the same thing; and sometimes they denote different things. In the latter case, a garrison is a place wherein forces are maintained to secure it, and where they keep regular guard, as a frontier town, a citadel, castle, tower, &c. The garrison should always be stronger than the towns-men.

GARTER, order of the, a military order of knighthood, the most noble and ancient of any lay order in the world, instituted by King Edward III. This order consists of twenty-six knights-Companions, generally princes and peers, whereof the King of England is the sovereign, or chief. They are a college or corporation, having a great and little seal.

Their officers are, a Prelate, Chancellor, register, king at arms, and usher of the black rod. They have also a dean, with twelve canons, and petty canons, vergers, and twenty-six pensioners, or poor knights. The Prelate is the head. This office is vested in the Bishop of Winchester, and has ever been so. Next to the Prelate is the Chancellor, which office is vested in the Bishop of Salisbury, who keeps the seals, &c. The next is the register, who by his oath is to enter upon the registry, the scrutinies, elections, penalties, and other acts of the order, with all fidelity. The fourth officer is garter, and king at arms, being two distinct offices united in one person. Garter carries the rod and sceptre at the feast of St. George, the protector of this order, when the Sovereign is present. He notifies the elections of new knights, attends the solemnity of their installations, carries the garter to the foreign princes, &c. He is the principal officer within the college of arms, and chief of the heralds.

All these officers, except the prelate, have fees and pensions. The college of the order is seated in the castle of Windsor, with the chapel of St. George, and the chapter-house erected by the founder for that purpose. The habit and ensigns of the order are, a garter, mantle, cap, George, and collar. The four first were assigned the knights companions by the founder; and the George and collar by Henry VIII. The garter challenges preeminence over all the other parts of the dress, by reason that from it the noble order is denominated; that it is the first part of the habit presented to foreign princes, and absent knights, who, and all other knights elect, are therewith first adorned; and it is of so great honour and grandeur, that, by the bare investiture with this noble ensign, the knights are esteemed companions of the greatest military order in the world. It is worn on the left leg between the knee and calf, and is enamelled with this motto, HoNI SOIT QUI MAL Y PENSE; i. e. "shame to him that thinks evil hereof." The meaning of which is, that King Edward, having laid claim to the kingdom of France, retorted shame and defiance upon him that should dare to think amiss of the just enterprize he had undertaken, for his recovering his lawful right to that crown, and that the bravery of those knights whom he had elected into this order was such, as would enable him to maintain the quarrel against those that thought ill of it.

The mantle is the chief of those vestments made use of upon all solemn occasions. The colour of the mantle is by the statutes appointed to be blue. The length of the train of the mantle only distinguishes the Sovereign from the knights companions. To the collar of the mantle is fixed a pair of long strings, anciently woven with blue silk only, but now twisted round, and made of Venice gold and silk, of the colour of the robe, with knobs, or buttons, and tassels at the end. The left shoulder of the mantle has from the institution been adorned with a large garter, with the device нONI SOIT, &c. within this is the cross of the order, which was ordained to be worn at all times by king Charles I. At length the star was introduced, being a sort of cross irradiated with beams of silver.

The collar is appointed to be compos ed of pieces of gold in fashion of garters, the ground enamelled blue, and the mot to gold.

The manner of electing a knight com

:

panion into this most noble order, and the ceremonies of investiture, are as follow when the Sovereign designs to elect a companion of the garter, the Chancellor belonging to this order draws up the letters, which, passing both under the Sovereign's sign manual and signet of the order, are sent to the person by garter principal king at arms, and are in this manner, or to the same effect. "We, with the companions of our most noble order of the garter, assembled in chapter, holden this present day at our castle at Windsor, considering the virtuous fidelity you have shown, and the honourable exploits you have done in our service, by vindicating and maintaining our right, &c. have elected and chosen you one of the companions of our order. Therefore, we require you to make your speedy repair unto us, to receive the ensigns thereof, and be ready for your installation upon the- -day of this present month, &c.

The garter, which is a blue velvet, bordered with fine gold wire, having commonly the letters of the motto of the same, is, at the time of election, buckled upon the left leg, by two of the senior companions, who receive it from the Sovereign, to whom it is presented upon a velvet cushion by garter king at arms, with the usual reverence, whilst the Chancellor reads the following admonition, enjoined by the statutes. "To the honour of God omnipotent, and in me. morial of the blessed martyr St. George, tie about thy leg,for thy renown,this noble garter; wear it as the symbol of the most illustrious order, never to be forgotten, or laid aside; that thereby thou mayest be admonished to be courageous, and having undertaken a just war in which thou shall be engaged, thou mayest stand firm, valiantly fight, and successively conquer."

The princely garter being thus buckled on, and the words of its signification pronounced, the knight elect is brought before the Sovereign, who puts about his neck, kneeling, a sky-coloured ribbon, whereunto is appendant, wrought in gold within the garter, the image of St. George on horseback, with his sword drawn, encountering with the dragon. In the mean time, the Chancellor reads the following admonition: "Wear this ribbon about thy neck, adorned with the image of the blessed martyr and soldier of Christ, St. George, by whose imitation provoked, thou mayest so overpass both prosperous and adverse adventures, that

having stoutly vanquished thy enemies, both of body and soul, thou mayest not only receive the praise of this transient combat, but be crowned with the palm of eternal victory.”

Then the knight elected kisses the Sovereign's hand, thanks his Majesty for the great honour done him, rises up, and salutes all the companions severally, who return their congratulations.

GAS. This term was first applied by Van Helmont, to denote the permanently elastic exhalations afforded in chemical processes. Dr. Priestley, whose extensive and successful researches into this departmet of natural philosophy, in the space of a few years, produced a revolution in the science of chemistry, used the word air as the generic term for permanently elas.ic fluids. Other chemical writers of great reputation have thought fit to revive Van Helmont's term, and confine the word air to the atmospheric fluid. As this has been found convenient, to prevent confusion of ideas, it is now generally adopted; the gases which are not fully treated under the articles of their respective bases, will properly find a place here.

GAS, ammoniucal. See AMMONIA.

GAS, carbonic acid. This is the first of the elastic fluids that appears to have been distinguished from common air, though its nature was not properly understood till it was investigated by Dr. Black. Its deadly properties, as it is met with in subterranean cavities, particularly the celebrated Grotto del Cano near Naples, occasioned it to be distinguished by the name of spiritus lethalis. Van Helmont first gave the name of gas, from a German word equivalent to our spirit, to this vapour produced from burning charcoal. He likewise called it spiritus sylvestris, and when arising from fermented liquors, spiritus vinosus. From its existing, in the inelastic state, in water, it was called fixed air, a name which Black and others long retained: Bewley termed it mephitic air, from its great abundance in nature combined with lime in the form of chalk, and it has been named the cretaceous and the calcareous acid, subsequent to the discovery of its acid nature. But carbonic acid has superseded all those, since it appears to have been ascertained that its radical is carbon. Of this, or rather of charcoal, according to the experiments of Lavoi sier, it contains twenty eight parts by weight, to seventy-two of oxygen. Guy

ton Morveau considers it as composed of 17.88 pure carbon, and 82.12 of oxygen. Carbonic acid gas exceeds every other in specific gravity, except the sulphurous. Hence the vapour in the Grotto del Cano rises but a little above the surface; and the choak damp of miners, which is this gas, lies on the ground. Thus, too, when it is emitted from a fer menting liquor, it first fills the empty portion of the vat, displacing the lighter atmospheric air; and then flows over the sides, almost as water would do. For the same reason, if a bottle filled with it be inverted over the flame of a candle at some distance, it will descend, and extinguish it. According to the experi. ments of Mr. Cavendish, one part of this, mixed with nine of atmospheric air, renders it incapable of supporting combustion.

From the powerful attraction of carbon for oxygen, the base of this gas is not easily decomposed; but Mr. Tennant effected it by introducing phosphorus into a coated glass tube, closed at one end, and over this powdered marble. A very small aperture only being left in the other end of the tube, and a red heat applied for some minutes, phosphate of lime and charcoal were found in the tube. Dr. Pearson did the same with phosphorus and carbonate of soda.

The carbonic acid gas is likewise de composed in part by hydrogen gas, assisted by electricity. In a glass tube eight lines in diameter, De Saussure exposed a column of four inches in height of carbonic acid gas, and three inches of hydrogen gas, over mercury, to the action of the electric fluid circulating between iron conductors, for twelve hours. The gases were at first condensed very rapidly, but by degrees more and more slowly, till in this period they were reduced to four inches. Of this, one inch was absorbed by potash, being carbonic acid gas, and the other three were nearly pure carbonic oxide, the hydrogen having formed water with the oxygen, abstracted from the carbonic acid. The mercury and the conductors were but very little oxyded. De Saussure had previously found that carbonic acid and hydrogen gases, standing together over mercury for the space of a twelve-month, had decreased in volume. GAS, Carbonic oxide. This gas was first made known by Mr. Cruickshank. Dr. Priestley had observed, that, when scales of iron mixed with charcoal, or with carbonate of barytes, were exposed to a

strong heat, large quantities of a combus. tible gas were extricated, which he sup posed to be heavy inflammable air, or carburetted hydrogen. He considered this as a strong argument against the mo dern theory of the formation of water; as, from the dryness of the ingredients, which were previously exposed to a red heat, and mixed and experimented upon immediately, and the quantity evolved, it could not be accounted for upon the supposition of the decomposition of wa ter. This objection was successfully combated by Mr. Cruickshank, showing that the air did not contain hydrogen, but was an oxide of carbon. It is equally procured from the oxides of other metals, and charcoal; but in proportion to the facility with which these give up their oxygen, the carbon is more or less saturated with it; so that the product is a mixture of carbonic acid gas and carbonic oxide, the proportion of the former decreasing as the process is continued.

The carbonic oxide gas, freed from carbonic acid by washing with lime-wa ter, is very little lighter than atmospheric air. It does not explode, when fired in atmospheric air, but burns with a blue lambent flame: with oxygen gas it detonates. It is noxious to animals. Water absorbs about a fifth only of its bulk. It is not absorbed by the pure alkalies, and does not precipitate lime-water. If it be mixed with hydrogen gas, and passed through an ignited glass tube, its oxygen unites with the hydrogen to form water, and charcoal is deposited. De Saussure, jun. however, ascribes this appearance of carbonaceous matter lining the tube to the action of the hydrogen on the lead in the glass, as he produced it by hydrogen alone with a glass tube; and could not by hydrogen and carbonic oxide in a tube of porcelain. The purest oxide of carbon is obtained, by passing the carbonic acid gas through red hot charcoal.

GAS, hydrogen. This is generally obtained from the reverse of the process for the decomposition of water. Iron moistened with water becomes oxyded, by decomposing the water; but this process is very slow. If the vapour of water be passed through a tube, containing iron wire, kept at a red heat, the decomposi tion will go on with much more celerity. But the readiest method is to employ an acid, as the sulphuric, diluted with five or six times its weight of water, poured on iron filings or turnings, or on zinc in small pieces. Zinc affords it the purest,

as that from iron is apt to be contaminated with carbon. Muriatic acid, diluted with twice or thrice its weight of water, may be employed, but it is less economical

Hydrogen gas is the lightest of all ponderable substances, particularly if received over quicksilver, and freed from any humidity which it may contain, by exposure to any substance that attracts water strongly. When perfectly dry, it is free from smell, but when it contains moisture, it is slightly fœtid. Though highly inflammable, it extinguishes burning bodies, if completely enveloped in it without the contact of oxygen. It is incapable of supporting life, but does not appear to possess any directly noxious quality, as it may be breathed for several respirations, or even nearly a minute. Fired, in combination with oxygen, it explodes very loudly; but if kindled as it escapes from the extremity of a capillary tube into the atmosphere, it burns calmly, with a white flame, the colour of which, however, may be varied by different substances dissolved in the gas. It is thus the philosophical fireworks without smoke or smell are formed. If a tube of glass, metal, or any elastic material, be held over a jet of inflamed hydrogen gas, musical tones will be produced, varying in depth and strength, according to the length, diame. ter, and material of the tube. A glass jar has a similar effect, but it must not be too wide, or so narrow as to extinguish the flame. Dr. Higgins first discovered this property.

A very high temperature is generally considered as necessary to produce the combination of hydrogen and oxygen. Biot compressed the two gases together in the syringe of an air gun; they took fire, exploded violently, and burst the syringe; but here the temperature was sufficiently increased by the pressure. A gentleman of Orkney, however, introduced nearly equal quantities of the two gases into a glass jar over mercury, which stood in a room without fire, and with little light, from the beginning of January to the end of May, when he found that, of twelve cubic inches, three and a half had disappeared. The residuum was still a mixture of the two gases.

The chief practical application of hydrogen gas is for the filling air-balloons.

GAS, hydrogen arsenicated. Scheele, dissolving tin in arsenic acid, observed the extrication of an inflammable gas, holding arsenic in solution. Proust afterwards obtained it by digesting arsenious acid and zinc in diluted sulphuric acid. It may VOL. V.

be procured, likewise, by treating arse. nious acid, or arsenic and iron fillings, or arsenic and tin filings, with muriatic acid; but still better by treating four parts of granulated zinc, and one of arsenic, with sulphuric acid diluted with twice its weight of water.

This gas is insoluble in water; does not render lime-water turbid; mixed with atmospheric air no diminution of bulk ensues, but the mixture, when fixed, detonates loudly, and deposits metallic arsenic; it has an alliaceous smell; it extinguishes burning bodies, and is fatal to animals; it is decomposed by oxygenated muriatic acid gas. If a lighted taper be immersed in a phial of this gas, it is instantly extinguished; but the gas burns at the mouth of the phial with a lambent white flame, which diffuses white fumes of arsenious acid. If it be inflamed in a phial with a small orifice, the flame gra, dually descends to the bottom of the phial, which becomes coated with crystallized metallic arsenic. Two parts of this gas, with one of oxygen, will explode loudly, and the products are water and arsenious acid; soap bubbles, made with a mixture of these gases, explode with a bluish white flame. Equal parts of the gases explode with a much more vivid flame, but less noise. A stream of this gas, burned in a large receiver filled with oxygen, emits a blue flame of uncommon splendour. According to Tromsdorff's calculation, a cubic inch of the gas contains about a quarter of a grain of the arsenic. Its specific gravity is rather more than half that of atmospheric air.

GAS, carburette hydrogen. There are several varieties of this gas, the hydrogen holding different proportions of carbon in solution, according to the process by which it is obtained.

The gas of stagnant water, which may be procured by stirring the mud at the bottom with a stick, and collecting the gas, as it rises in bubbles, in an inverted bottle, is this compound, as is also the fire damp of coal mines. The vapour of water passed through a tube containing ignited charcoal consists of this gas and carbonic acid, which may be separated by agitating the mixture with lime diffused in water. The vapour of ether, or of alcohol, passed through a red hot tube of porcelain, coated with clay, affords the same products. If three parts of concentrated sulphuric acid, and one of alcohol, be distilled in a glass retort with a gentle heat, a carburetted hydrogen comes over. This is distinguished by the name of olefiant gas, from its property of forming an