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 So vereign, to whom it is presented upon a velvet cushion by garter king at arms, with the usual reverence, whilst the Chancellor reads the followirig admoni tion, 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 buck led 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 rib bon, 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, butbe crowned with the palm of eternal victory." Then the knight elected kisses the So vereign'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 permanent ly elastic exhalations afforded in chemi cal processes. Dr. Priestley, whose ex tensive and successful researches into this departmet of natural philosophy, in the space of a few years, produced a re volution in the science of chemistry, used the word air as the generic term for permanently elastic fluids. Other chemical writers of great reputation have thought fit to revive Van Helmont's term, and confine the word air to the at mospheric fluid. As thishas 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.
Ges, 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 un derstood till it was investigated by Dr. Black. Its deadly properties, as it is met with in subterranean cavities, parti cularly the celebrated Grotto del Cano near Naples, occasioned it to be distin guished by the name of spiritus lethalis. Van Ilelmont first gave the name of gas, from a German word equivalent to our spirit, to this vapour produced from burn ing charcoal. He likewise called it
spiritussylvestris, and when arising from fermented liquors, spiritus vinosus. From its existing, in the inelastic state, in wa ter, 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 su perseded 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 eomposed of 37.88 pure carbon, and 82.12 of oxygen.
Carbonic acid gas exceeds every other in specific gravity, except the sulphur ous. Hence the vapour in the Grotto del Cano rises but a little above the sur face ; and the choak damp of miners, which is this gas, 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 ex tinguish it. According to the experi ments of Mr. Cavendish, one part of this, mixed with nine of atmospheric air, renders it incapable of supporting com bustion.
From the powerful attraction of car bon for oxygen, the base of this gas is not easily decomposed ; but Mr. Tennant ef fected it by introducing phosphbrus 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, as sisted 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 circula ting between iron conductors, for twelve hours. The gases were at first condens ed 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 hy drogen having formed water with the oxygen, abstracted from the carbonic acid. The mercury and the conductors were but very little oxyded. De Saus sure had previously found that carbonic acid and hydrogen gases, standing toge ther over mercury for the space of a twelve-month, had decreased in volume.