

GALL-NUTS 531 



opaque glass, sometimes with intumescence, but does not fuse into a bead. It is 

 remarkable for containing from 45 to 55 per cent, of the earth yttria ; its remaining 

 constituents being silica, 25'8 ; oxide of cerium, 17'92 ; oxide of iron, 11'43. This 

 mineral, which is very rare, is found in Sweden ; also at Disko in Greenland ; in 

 the south of Norway ; and near Galway. Its peculiar constituent was discovered by 

 Professor Gadolin, after whom it is named. 



G AGATES. The name by which jet was known to the ancients, derived pro- 

 bably from Gagis, a town in Lycia, where it was said to have been found. See JET. 



GAXiACTXTXi, so called from its giving the colour of milk to water, when 

 triturated with that fluid ; analyses have shown it to be a variety of natrolite. See 

 NATROLITE. 



CAXiACTOMETER, or LACTOMETER, is an instrument to ascertain the 

 quality of milk ; an article often sophisticated in various ways. Fresh milk, rich in 

 cream, has a less specific gravity than the same milk after it has been skimmed; 

 and milk diluted with water becomes proportionally lighter. Hence, when our 

 purpose is to determine the quantity of cream, the galactometer may consist merely 

 of a long graduated glass tube standing upright upon a sole. Having filled 100 

 measures with the recent milk, we shall see, by the measures of cream thrown up, 

 its value in this respect. A delicate long-ranged glass hydrometer, graduated from 

 1-000 up to 1-060, affords the most convenient means of detecting the degree of 

 watery dilution, provided the absence of thickening materials has been previously 

 ascertained by filtration. Good fresh milk indicates from 1-030 to 1'032; when the 

 cream is removed, 1-035 to 1-037- When its density is less than 1-028, we may infer 

 it has been thinned with water. 



GAXiACTOSZi. A saccharine substance obtained by boiling sugar of milk with 

 dilute acids. 



G-AXiBANUM is a gum-resin, which exudes either spontaneously or from incisions 

 made in the stem of a plant of the family of Umbellifercs, which grows in Africa, 

 particularly in Ethiopia. The source of this gum-resin is not distinctly known, but 

 is believed to be the Ferula galbaniflua. Galbanum contains 67 of resin ; 19*3 of 

 gum ; 6-4 of volatile oil and water ; 7'5 of woody fibres and other impurities ; with 

 traces of acid malate of lime. 



CAIsETTA (Plomb sulfure, Fr. ; Bleiglanz, Ger.) is a sulphide (sulphuret) of 

 lead. It is of a lead-grey colour, crystallises in the cubical system, and is suscep- 

 tible of cleavages parallel to the faces of the cube; sp. gr. 7'7592 ; fusible at the 

 blowpipe with exhalation of sulphureous vapours ; is easily reduced to metallic lead. 

 Nitric acid first dissolves it, and then throws down sulphate of lead as a white 

 precipitate ; the solution affording with plates of zinc brilliant laminae of lead (arbor 

 Saturni}. It consists of sulphur, 13; lead, 85; with a little iron, and generally a 

 small quantity of silver. This is the richest ore of lead, and it occurs in almost 

 every geological formation, in veins, in masses, or in beds. Galena in powder, called 

 Alquifoux, is employed as a glaze for coarse earthenware. See LEAD. 



GAZiIPOT is a name of a white semi-solid viscid resin, found on fir-trees ; or an 

 inferior sort of turpentine, poor in oil. 



GALL OP AXJXIVIAXiS. A peculiar fluid, called also bile, secreted by the cells 

 of the liver ; it is taken up by the biliary ducts, which unite to form the hepatic duct, 

 by which the secretion is either discharged directly into the duodenum, or is conveyed 

 through the cystic duct into the gall bladder, wherein it becomes accumulated, and to 

 some extent inspissated. Gall or bile from different animals finds several uses in the 

 arts. It is used for cleansing woollen goods, and by artists it is employed to ensure 

 the uniform spreading of water colours upon paper. For the constitution of the gall 

 of different animals, see Watts's ' Dictionary of Chemistry.' See BILE. 



G-AXiXi OP GXiASS, called also Sandiver, is the neutral salt skimmed off the 

 surface of melted crown glass ; which, if allowed to remain too long, is apt to be re- 

 absorbed in part, and to injure the quality of the metal, as the workmen call it. See 

 GLASS. 



O ALL ATE S, Salts consisting of gallic acid combined with bases; the most 

 important being that with oxide of iron, constituting a principal part of the black 

 dye. 



GALLERY, in mining, an underground horizontal excavation. 



GALLIARD, a North of England term for a hard, smooth, flinty grit. 



GAXiXiXC ACID is the peculiar acid extracted from gall-nuts. See GALL-Ntrrs. 



GAIiXiXPOXiX OH is a coarse olive oil, containing more or less mucilage, 

 imported from a seaport so named, of the province of Otranto, in the kingdom of 

 Naples. See OLIVE OIL. 



GAX.X.-xriTTS or GAX.X.S (Noix de Galle, Fr.; Gallapfel, Ger.) are excres- 

 cences found upon the leaves and leaf-stalks of a species of oak, called Quercus 



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