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Gilding, Silvering, and Tinning (Grammes of nitric acid)

grammes of nitric acid and the same weight of ❘ be laid on, and afterwards burnished. The last hydrochloric acid. To the solution are added 1.2 grammes of tin and 12 grammes of butter of anbutter of antimony, and, when all are dissolved, the solution , the solution is diluted with 500 grammes of water .

A mixture is now prepared by heating together 80 grammes of oil of turpentine, 16 grammes of sulphur, and 16 grammes of Venice turpentine.

When the sulphur is dissolved 50 grammes of oil of lavender is added. The gold solution is now added, and the two are well stirred together, until the aqueous solution becomes decolorized, showing that all the gold has united with the balsam. The watery portion is then poured away, and the oily fluid is washed with warm water, and then heated.

When the last trace of moisture has disappeared, 65 grammes more of lavender oil and 100 grammes of oil of turpentine are added, and the whole warmed to insure the perfect admixture. While quite fluid 5 grammes of subnitrate of bismuth are added. Afterwards the clear part is decanted from any reduced gold and other insoluble matand the balsam is concentrated to a fit consistence for painting with. The balsam so prepared is a thick fluid, of a pale-green color, the gold being perfectly dissolved. When proper care is taken to remove all moisture this prepa' tion never blispreparation never blisters in burning. To Gild Leather In order to impress gilt figures, letters, and other marks upon leather, as on the covers of books, edgings for doors, etc., the leather must first be dusted over with very finely powdered yellow resin or mastic gum. The iron tools or stamps are now arranged on a rack before a clear fire, so as to be well heated, without becoming red hot. If the tools are letters, they have an alphaan alphabetical arrangement on the rack. Each letter or stamp must be tried, as to its heat, by imprinting its mark on the raw side of a piece of waste leather.

A little practice will enable the workman to judge of the heat. The tool is now to be pressed downis now to be pressed downwards on the gold-leaf, which will of course be indented, and show the figure imprinted on it.

The next letter or stamp is now to be taken and stamped in like manner, and so on with the others, taking care to keep the letters in an even line with each other, like those in a book. By this operaa book. By this operation the resin is melted, consequently the gold adthe gold adheres to the leather. The superfluous gold may then be rubbed off by a cloth, the gilded impresgilded impressions remaining on the leather. In this, as in every other operation, adroitness is acquired by practice.

The cloth alluded to should be slightly greasy, to retain the gold wiped off (otherwise there will be great waste in a few months); the cloth will thus be soon completely saturated or loaded with the gold. When this is the case, these cloths are generally sold to the refiners, who burn them and recover the gold. Some of these afford SO much afford so much gold by burning as to be worth from seven to ten dollars.

To Gild Writings, Drawings, etc. on Paper or Parchment.

Letters written on velum or paper are gilded in 3 ways: in the first, a little size is mixed with the ink, and the letters are written as usual ; when they are dry, a slight degree of stickiness is prostickiness is produced by breathing on them, upon which the gold leaf is immediately applied, and by a little pressa little pressure may be made to adhere with sufficient firmsufficient firmness. In the second method, some white-lead or chalk is ground up with strong size, and the let- , and the letters are made with this by means of a brush; when the mixture is almost dry the gold leaf may method is to mix up some gold powder with size, and to form the letters of this by means of a brush.

It is supposed that this latter method was that used by the monks in illuminating their missals, psalmissals, psalters, and rubrics. To Gild the Edges of Paper.

The edges of the leaves of books and letter paper are gilded whilst in a horizontal position in the bookbinder's press, by first applying a coma composition formed of four parts of Armenian bole, and one of candied sugar, ground together with water to a proper consistence, and laid on by a brush, with the white of an egg. This coating, when nearly dry, is smoothed by the burnisher , which is generally a crooked piece of agate, very smooth, and fixed in a handle. It is then slightly moi moistened by a sponge dipped in clean water squeezed in the hand. The gold-leaf is now taken upon a piece of cotton from the leathern cushion, and applied on the moistened surface. When dry it is to be burnished by rubbing the agate over it repeatedly from end to end, taking care not to wound the surface by the point of the burnisher.

A piece of silk or Indiapaper is usually interposed between the gold and the burnisher. Cotton-wool is generally used by bookbinders to take the leaf up from the cushion, being the best adapted for the purpose on account of its pliabilits pliability, smoothness, softness, and slight moistness.

To Gild Silk, Satin, Ivory, etc., by Hydrogen Gas.

Immerse a piece of white satin, silk, or ivory in a solution of chloride of gold, in the proportion of 1 part of the chloride to 3 of distilled water.

Whilst the substance to be gilded is still wet, imgilded is still wet, immerse it in a jar of hydrogen gas; it will soon be covered by a complete coat of gold.

Another Method.

The foregoing experiment may be very prettily and advantageously varied as follows: Paint flowers or other ornaments with a very fine camel-hair pencil, dipped in the above-mentioned solution of gold, on pieces of silk, satin, etc., and hold them over a Florence flask, from which hydrogen gas is evolved, during the decomposition of the water by sulphuric acid and iron filings. The painted flowers, etc., in a few minutes, will shine with all the splendor of the purest gold. A coating of this kind will not tarnish on exposure to the air or in washing.

Oil Gilding on Wood.

The wood must first be covered, or primed, by 2 or 3 coatings of boiled linseed-oil and carbonate of lead, in order to fill up the pores and conceal the irregularities of the surface occasioned by the veins in the wood. When the priming is quite dry a thin coat of gold size must be laid on. This on. is prepared by grinding together some red oxide of lead with the thickest drying oil that can be procured, and the older the better. That it may work freely, it is to be mixed, previously to being used, with a little oil of turpentine, till it is brought to a proper consistence. If the gold-size is good it will be sufficiently dry in 12 hours, more or less, or less, to allow the artist to proceed to the last part of the process, which is the application of the gold. For this purpose a leaf of gold is spread on a cushion (formed by a few folds of flannel secured on a piece of wood, about 8 inches square, by a tight covering of leather), and is cut into strips of a proper size by a blunt pallet-knife; each strip, ; each strip being then taken upon the point of a fine brush , is applied to the part intended to be gilded, and is then gently pressed down by a ball of soft cotton. soft cotton The gold immediately adheres to the sticky sursticky surface of the size, and, after a few minutes, the dex- | gam, but of course will remain on the copper. terous application of a large camel's-hair brush sweeps away the loose particles of the gold-leaf without disturbing the rest. In a day or two the size will be completely dried, and the operation will be finished.

The advantages of this method of gilding are that it is very simple, very durable, and not readily injured by changes of weather, even when exposed to the open air; and when soiled it may be cleaned by a little warm water and a soft brush. Its chief employment is in out-door work. Its disadvantage is that it cannot be burnished, and therefore wants the high lustre produced by the following method:

To Gild by Burnishing.

This operation is chiefly performed on picture frames, mouldings, beadings, and fine stucco-work.

The surface to be gilt must be carefully covered with a strong size, made by boiling down pieces of white leather or clippings of parchment till they are reduced to a stiff jelly. This coating being dried, 8 or 10 more must be applied, conmixed with fine Paris plaster or washed chalk. When a sufficient number of layers have been put on, varying according to the nature of the work, and the whole is become quite dry, a moderately thick layer must be applied, composed of size and Armenian bole, or yellow oxide of lead. While this last is yet moist the gold-leaf is to be put on in the usual manner.

It will immediately adhere on being pressed by the cotton ball; and, before the size is become perfectly dry, those parts which are intended to be the most brilliant are to be carefully burnished by an agate or a dogs' tooth, fixed in a handle.

In order to save the labor of burnishing, it is a common, but bad practice, slightly to burnish the brilliant parts, and to deaden the rest by drawing a brush over them dipped in size; the required polished and the unpolished gold is indeed thus obtained; but the general effect is much inferior to that produced in the regular way, and the smallest drop of water falling on the sized part occasions a stain. This kind of gilding can only be applied on in-door work; as rain, and even a considerable degree of dampness, will occasion the gold to peal off. When dirty it may be cleaned by a soft brush, with hot spirit of wine, or oil of turpentine.

Matting.

The parts to be burnished (in gilding on metals) being covered with the usual guarding, the piece is fastened by five iron wires to the end of an iron rod; it is then to be highly heated until the guarding becomes brown, when the gilding will be found to have acquired a fine gold color. It is now to be covered with a mixture of common salt, nitre, and alum, liquefied in the water of crystallization they contain; the piece to be carried again to the fire and heated until the saline coating is in a state of fusion and becomes nearly transparent, when it must be withdrawn and suddenly plunged into cold water, which removes both coating and it afterwards in very weak nitric acid, and wash it repeatedly in several separate tubs of water. It may be dried either by exposure to air, or gently wiping it with clean, soft, dry linen.

To Gild Copper, etc., by Amalgam.

Now place the piece or pieces so operated on in a clean oven or furnace, where there is no smoke.

If the heat is a little greater than 660°, the mercury of the amalgam will be volatilized, and the copper will be beautifully gilt. contrived that the volatilized mercury is again In the large way of gilding, the furnaces are so condensed and preserved for further use, so that there is no loss in the operation. There is also a contrivance by which the volatile particles of mercury are prevented from injuring the gilders.

To Gild Steel.

Pour some of the ethereal solution of chloride of gold into a wineglass, and dip therein the blade of a new penknife, lancet, or razor; withdraw the instrument and allow the ether to evaporate. The blade will be found to be covered by a very beauvery dry sponge, may be dipped in the ether and tiful coat of gold. A clean rag, or small piece of used to moisten the blade with the same result. liquid into a glass, which must undoubtedly lose In this case there is no occasion to pour the by evaporation; but the rag or sponge may be moistened by it by applying ether to the mouth of the phial. This coating of gold will remain on the steel for a great length of time, and will preserve it from rusting. This is the way in which swords and other cutgilded with great advantage to secure them from lery are ornamented. Lancets too are in this way rust.

Gold Powder for Gilding.

Gold powder may be prepared in three different ways Put into an earthen mortar some gold-leaf the mixture till the gold is reduced to extremely with a little honey or thick gum -water, and grind minute particles.

When this is done, a little warm water will wash out the honey or gum, leaving the gold behind in a pulverulent state. (or the leaf) in nitro-muriatic acid, and then to Another. Another way is, to dissolve pure gold precipitate it by a piece of copper, or by a solution of sulphate of iron . The precipitate (if by copper) must be digested in distilled vinegar and then dried. This precipitate will be in the form of a washed (by pouring water over it repeatedly) and very fine powder; it works better and is more easily burnished than gold-leaf ground with honey as above. powder is by heating a prepared amalgam of gold