Page:Encyclopædia Britannica, Ninth Edition, v. 10.djvu/612

594 five thickness of the gold-leaf used in ancient gilding, the traces of it which yet remain are remarkably brilliant and solid. Gildiiig has in all times occupied an important place in the ornamental arts of Oriental countries; and the native processes pursued in India at the present day may be taken as typical of the art as practised from the earliest periods. For the gilding of copper, employed in the decoration of temple domes and other large works, the following is an outline of the processes employed. The metal surface is thoroughly scraped, cleaned, and polished, and next heated in a ﬁre sufﬁciently to remove any traces of grease or other impurity which may remain from the operation of polishing. It is then dipped in an acid solution prepared from dried unripe apricots, and rubbed with pumice or brick powder. Next, the surface is rubbed over with mercury which forms a superficial amalgam with the copper, after which it is left some hours in clean water, again washed with the acid Solution, and dried. It is now ready for receiving the gold, which is laid on in leaf, and, on adhering, assumes a grey appearance from combining with the mercury, but on the application of heat the latter metal volatilizcs, leaving the gold a dull greyish hue. The colour is brought tip by means of rubbing with agate burnishers. The weight of mercury used in this process is double that of the gold laid on, and the thickness of the gilding is regulated by the circumstances or necessities of the case. For the gilding of iron or steel, the surface is ﬁrst scratched over with chequered lines, then washed in a hot solution of green apricots, dried, and heated just short.of red-heat. The gold-leaf is then laid on, and rubbed in with agate burnishcrs, when it adheres by catching into the prepared scratched surface. Modern gilding is applied to numerous and diverse surfaces and by various distinct processes, so that the art is prosecuted in many_w-.ys, and is part of widely different ornamental and useful arts. It forms an important and essential part of frame-making (see ); it is largely employed in connexion with cabinet-work, decorative painting, and house ornamentation ; and it also bulks largely in bookbinding and ornamental leather work. Further, gilding is much employed for coating baser metals, as in button-making, in the gilt toy trade, in electro-gilt reproductions, and in electro-plating; and it is also a characteristic feature in the decoration of pottery, porcelain, and glass. As details of the processes employed in connexion with these various substances will be found in the parts of this work where the technical processes to which they are related are described, it is only necessary here to indicate how the processes of gilding differ from each other. The various processes fall under one or other of two heads—mechanical gilding and gilding by chemical agency.

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{{ti|1em|{{11fine|{{nowrap|Gilding of Pottery and Porcelain.—}}Thc quantity of gold consumed for these purposes is very large. The gold used is dissolved in aqua-regia, and the acid is driven off by heat, or the gold may be precipitated by means of sulphate of iron. In this pulverulent state the gold is mixed with {fth of its weight of oxide of bismuth, together with asmall quantity of borax and gum water. The mixture is applied to the articles with a camel’s hair pencil, and after passing through the fire the gold is of a dingy colour, but the lustre is brought out by buriiisliing with agate and bloods-tone, and afterwards cleaning with vinegar or white-lead.}}}}  GILEAD (1:35;, 2'.c., «hm-t1" m- “magi-.1") i..- sometimes used,both in earlier and in later writers, to denote the whole of the territory occupied by the Israelites eastward of Jordan, extending from the Amen to the southern base of Hermon (Dent. xxxiv. l ; Judg. xx. 1 ; Jos., .1221. xii. 8. 3, 4‘). More precisely, however, it was the usual name of that mountainous district which is bounded on the Nrby the Hicromax (Yarinuk), on the E. by the Jordan, on the S. by the Arnon, and on the W'. by a line which may be said to