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matter, make a fort of white veins ; but fuch cracks and veins arc not to be fcen in the marble of thefe columns. Thefe obfervations naturally lead us to an analogy between this marble and cryftal in their origin and formation, as the columns of cryftal are alike pure and homogeneous, alike of a regularly angular figure, and both are alike free from veins, cracks, and extraneous fubftances. Sec Philof. Tranf. N«. 199, 212, 241. Lowth. Abrid. Vol. 2. p. 511. feq. See alfo the article Touchstone.
GIAR Alnabar, in botany, a name given by Avifenna, Serapio, and the reft of the Arabian writers to the potamogeiton of thofe times. This is tranflated by fome the water ruin, but that is founded on an error ; it is certain that the plant thus called by the Arabians, was very different from the potamo- geiton of our times. Avifenna tells us it had flowers refem- bhng thofe of the water lily ; and it feems either to have been the fegitta aquatica or water arrow head, or elfe the bu- tomus, or Tome of the fmaller fpecies of nymphaea.
GIAROLA, in zoology, the name of a bird of the lark kind, remarkable for its very long heel. It is of the fize of the common lark. Its head, neck, back, and wings, are of a mottled colour refembling that of the quail. The general colour of the feathers is a chefnut brown, and their edges are variegated with white, yellow, and red ; the back part of its head has a fort of crown or ring of white feathers. Its belly is white ; its tail is fo fhort that it feems to have none ; it is bifid however, and is elegantly variegated with chefnut colour and white. AldrovancL de Avibus. Lib. 17. Cap. 39.
GIAROLO, in zoology, a name by which a fmall bird of the fnipe kind, remarkable for its white tail, is known In the markets of Italy. It very much refembles the bird we call in Engliih the ftint, but its beak is broad at the bafe, and tapers to a point, and its legs are thicker and fhorter. It is not known among authors by any Latin name, except that Aldrovandus has called it the cindus tert'tus, and cinclus is a very indeterminate name, being applied by different au- thors to feveral different birds. AldrovancL Lib. 20. Cap. 56. See Cinclus and Stint.
GIBBOUS, (Cyd.) crooked or hump-backed. Gibbojity is a preternatural incurvation of the fpina dorfi either backward, or on one fide^ Infants are more fubject to this diforder than adults, and it oftner proceeds from external, than from in- ternal caufes. A fall, blow, or the like violence frequently thus diftorts the tender bones of infants. When it proceeds from an internal caufe, it is generally from a relaxation of the ligaments that fuftain the fpine, or a caries of its vertebrae ; though the fpine may be inflected forward, and the back thrown out, by a too ftrong and repeated action of the abdo- minal mufcles ; and this if not timely redrefTed, ufually grows up and fixes as the bones harden, till in adults it is totally irretrieveable : but when the diforder is recent, and the per- fon young, there are fome hopes of a cure. The common method is by a machine of paftboard, wood, or flee], which is made to prefs principally upon the gibbous part, and thi by long wearing may let all right. The furgeons however have a different inftrument which they call a crofs, much more efficacious though not quite fo convenient in the wearing ; by the ufe of this, the parts are always prevented from growing any worfe, and are often cured. During the application of thefe afliftances, the parts mould be at times rubbed with Hungary water, fpirit of Lavender, and the like, and de- fended with a ftrengthening plafter of oxycroceum, opodel- doc or the like. Hei/ler's Surg. P. 2. p. 21.
Gibbous fijh, Gibbofus Pifcis, in zoology, a name given by Mr. Ray to the fifh called by the Dutch kromrugh. It is a fmooth fifh without fcales, its belly is white, its fins and tail black. It grows to a confiderable fize, fometimes to four feet. It is caught all over the Eaft Indies, near the fea fhores, and is very firm, and much efteemed at table. It has its name from the remarkable rifing of its back, which is liki that of the pearch, but much higher. Ray's Ichthyolog. Ap pend. p. 4.
G1BUR, a general name given by fome chemical writers, to all medicines drawn by their art from metallic or mineral fubftances.
GIFFT MEHL, the name given by the German chemiits and metal I ur gifts, to the firft appearance of arfenic, or the grey flowers arifmgfrom the roafting of cobalt, and {ticking to the long wooden funnel, which they carry from 'the furnaces. The grey colour of thefe flowers is occafioned by the fmoak of the fuel ; and when they are afterwards fublimed in a clofe veffel, the arfenical flowers begin to grow clammy in that part of the veffel which is Iaft made hot by the continuation of the fire, and there form themfelves into a ponderous thick fublimate.
Neverthelefs this fublimate neither runs out, nor gets to the bottom of the veffel when the fire is encreafed. A tenacious doughy clamminefs is indeed communicated to arfenic by the fire ; but fire alone cannot make it melt, but refolves it into a fmoak, which when it can find no way to efcape, often burfts the veffels in which it is confined. The yellow arfe- nic, which has one tenth part fulphur, is by that mixture Suppu Vol. L
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much more eafily formed into a folid fublimate than the white arfenic alone; but the red arfenic, which contains double that^ quantity of fulphur, cannot eafily be formed into a fublimation by afcent, hecaufe of its extream readinefs to fufe. The beft way £of preparing this is therefore to raife it out of a retort in the large and long neck of which it may be condenfed, and thence fall wbile*yet fluid into the receiver. Arfenic of this kind may be immediately produced out of fome fpecies of pyrites without ajiy previous addition ; or by mixing a fulphureous pyrites of the common kind with one of the white ones, or with any other ore of arfenic ; and by this procefs there will be feparated an arfenic ei- ther yellow or red, according to the fmaller or larger proportion of the fulphur in the mixture of the whole. Cramer's Art. of AfTay. p. 408.
The word gifft meal is German, and fignifies poifonous meal or flower.
GIFT, Donum, in law, is a conveyance which paffeth either lands or goods, and is of a larger extent than a grant, be- ing applied to things moveable and immoveable ; yet as to things immoveable, when taken ftrictly, it is applicable on- ly to lands and tenements given in tail ; but gift and grant are often confounded.
GIGAROS, in botany, a name given by fome writers to the dracontium.
GIGARTON, the ftone or kernel of a grape or raifin. ^Egineta obferves, that grape-ftones are drying and refrigera- ting; and the ftones of raifins, on analyfis, afford an acid fpirit, and empyreumatic oil, and as fome fay, a very confiderable quantity of a volatile fait.
GIGERLE, a term ufed by fome writers, to exprefs the of- fals of poultry of any kind, including the interlines, extre- mities, and whatever elfe is thrown away before the drefling.
GIGiVIILLS, a kind of fulling mills, for fulling and burling of woollen cloth, prohibited^ anno 5 and 6. Ed. 6. c. 22.
GIGOT, in the manege. A branch after the form of a gigot or leg, is a branch, the lower part of which is round, and called in French gargouillc.
GILAM-HIO, in the materia medica, a name ufed by fome authors, for a peculiar fort of the lignum aloes, which is foft, whitifh, and very fweet fcented. Gamell. Syll. p. 87.
GLLARUM, in botany, a name ufed by Marcellus, for^the ferpyllum.
GILDING {Cyd.) — To gild iron with water gold, that is by means of quick filver, has formerly been thought diffi- cult, if not impracticable; but Mr. Boyle tells us* it may be done by cafing the iron when bright, with copper, by frequently immerfing it in a ftrong folution of good vitriol containing copper, in warm water ; and letting the iron dry of itfelf, each time, till copper enough remains upon it ; and then the iron may be gilt like copper, with the amalgam of gold and mercury. Boy/is works Abr. Vol. 1. p. 152. See Gilding, Cyd.
Gilding on china ware. The gold is very much valued on drina ware, and would be much more fo, were it not that it is very liable to lofe its luftre, and to rub off. 7"he Chi- nefe at prefent have a method of preventing both thefe accidents in a great meafure, by means of a fort of polifh- ingj which they give it after it is laid on. They prepare for this purpofe a fine piece of agate, which they polifh on one furface in as perfect a manner as poflible. With this they rub over the gold as it lies on the porcelain feveral times, when it firft comes from the baking. This gives the gold a luftre which it would not otherwife have, and fixes it down to the ware in fuch a manner, that it cannot eafily be got off. The principal mifchief that gold thus laid on is fubject to, is the tarnifhing, or growing dull; this is remedied by the fame fort of means. They wet the veffel upon which they would revive the luftre of the gold, in common clean water, and while it is wet, they rub it with the fame polifhed agate, adding a little fair water at times to keep it moift. If the gold has not been laid on well at firft, this may poffibly raife it or take it off in fome places ; but if it was originally put on with the help of this ftone, as all the gold on porcelain now is, the rubbing it with it a fecond time never gives it any fcratches, but recovers its priftine luftre and beauty. It muft be obferved, that the rubbing with this ftone muft be all done one way, both in the firft laying on the gold, and in the brightning it up afterwards. This may ferve as a method for us as well as the Chinefe, not only to recover the beauty of our tarnifhed gilt china ware, but alfo to lay gold upon fome of our home manufactures of this kind. Obfer. Sur les Coutumes de l'Afie.
Gilding on vuood. This is performed two ways ; the firft called plain, the other burniflied gilding. In the firft, the leaf gold is laid upon a coat of whiting, which is laid feveral times over upon the wood, and allowed to dry each time; after which it is watered, and then the gold is laid gently on with a piece of cotton or otherwife; as the whiting dries the gold adheres, and the loofe pieces be- ing afterwards taken off, the work is finifhed ; for this will not bear burnifhing.
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