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the apparatus, near the battery, are two wooden stands C, supporting an iron rod which passes through a certain number of wooden spools carrying the wire to be gilt. These spools turn freely upon the rod, and the unwound wires, before dipping into the bath, are pressed against a copper or brass rod D connected with the negative, zinc, pole of the battery; thus the wires are connected with this pole. The wires dip into the bath to about two-thirds of its depth, and are kept stretched by small grooved pulleys EE of glass, porcelain, or ivory, rolling freely upon glass or ivory axes, which are kept near the bottom by supports screwed on the top edges of the kettle. At the bottom of the bath, and crossing the wires to be gilt, are two or more platinum wires GG, the vertical branches of which communicate with the positive, or carbon, pole. These platinum anodes must nowhere touch wires to be gilt, as these two kinds of wire represent the two poles of the battery in the bath. At the other end of the apparatus is another series of wooden reels M, upon which the gilt wire is wound up. These reels are fixed to the square iron axis which traverses them, and which is turned by gearing, slowly enough to ensure a good gilding to the wire, during its passage through the bath. After passing through the gilding bath, the wires are rinsed and dried by winding over two wooden rollers H H revolving freely upon their axes, and plunged by means of grooved rollers into the first trough, filled with a weak solution of cyanide of potassium, which cleans and brightens the gilding; they then pass into the second trough filled with water, which is constantly replaced, which removes the salts from the wires. The drying rollers K, covered with several layers of calico, are moved by gear in opposite directions; the wires are thoroughly dried in a flat tube L, kept at a dull redheat in the furnace L'. In a kettle of the size named, 20 wires may be gilt at the same time. Copper wires are generally previously silvered and passed once through a drawplate, to avoid the cleansing process

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before gilding. The more intense the battery, or the slower the wires pass through the bath, so will the deposit of gold be increased; and it will be well to weigh the bobbins before and after the operation, for which purpose the spools for winding up and winding out should be of the same weight. This gilding requires constant supervision, either for uniting the broken wires, the severed parts of which may touch the anodes and stop the operation; or for regulating the intensity of the battery, which, if too powerful, will produce a red gilding, or, if too weak, a green gilding. Baths of double cyanide of gold and potassium are employed, cold or slightly tepid; baths with phosphate and bisulphite of soda are used for hot electrogilding, but they are concentrated until the proportion of water is one-half of that indicated. As the platinum anodes do not make up for the metallic loss of the bath, it is frequently necessary to add new portions of metal and salts, in the manner already described. Pure gold wire is sometimes gilt, in order to impart to it a more uniform and deeper shade. After being gilt, the wire is passed through the draw-plate or the rollers. By the drawplate it is diminished by about onefourth or one-half of a number to remove the dulness of the deposit, and bring up the lustre. When the gilt wire is flattened between the rollers, its surface is bright or dull, according to the state of the surface of the rollers. Silvering, or any other metallic electrodeposit upon thin wires, can be effected in a similar manner.

Gilding with a Dead Lustre.-1. By the slow deposit of a large proportion of gold. This gilding is very durable, but dull and earthy in appearance, and is costly. 2. By acids; giving a dead lustre to the metallic surface, before gilding, and by the processes indicated in the cleansing operations. This is employed for small articles, or when gilding by dipping, for bronze articles, or large embossed work. 3. With frosted silver, by depositing upon the object to be gilt a coat of frosted silver, and then

gilding in a good bath; this method is expensive, the burnished parts are greenish, and the intermediary coat of silver is more easily blackened by sulphur fumes than gold. 4. By copper, by depositing a solution of sulphate of copper decomposed by a battery a coat of this metal, which possesses a pink dead lustre. The whole is rapidly passed through the compound acids for a bright lustre, and the mercurial solution, and then gilt in a good bath. When the dead lustre obtained in the bath is perfect, the compound acids may be dispensed with, and merely place the article in the mercurial solution before it is gilt. This mode is generally preferred, as the gilding is very handsome in lustre and colour. The burnished parts will be red, if vinegar or soap-water is used; and of a fine yellow colour, if the burnishing tool be wetted with a decoction of flax-seed, or of marsh-mallow root. If the gold deposit is of insufficient thickness, it will blacken in time, by the oxidization of the intermediate coat of copper. 5. Dead lustre by mercury, or the old process of gilding by fire, which furnishes the most durable gilding, although costly.

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brush of stout brass wire into a solution of nitrate of binoxide of mercury until it becomes completely white, it is passed over the amalgam, a portion of which is carried away. The object, previously well cleansed, is scratch-brushed in every direction, and the brush must be frequently dipped into the mercurial solution to facilitate the regular and even spreading of the amalgam. This operation requires great care to obtain a uniform coat upon the hollow and raised parts. When the back part of a piece does not require gilding, the flat outline, and the back edge, should be gilt, sc that the naked copper shall cause nc injury in the subsequent operations. The article, when uniformly covered with the amalgam, is heated upon a charcoal fire without draught, which rests upon a cast-iron plate. It is advisable to employ a gilding forge, which allows the workman to watch the operation from behind a glass frame, which protects him from the mercurial vapours. The entire attention is now required for watching the process. With the left hand covered with a thick glove of buckskin, turn the piece in every direction upon the fire, and, as the Gilding by Fire or Mercury.-Mer- mercury disappears, with the right cury gilding will furnish gold with a hand strike the article in every direction bright or a dead lustre, scratch-brushed, with a brush, the handle and the bristles ormolued, and with different shades. of which must be long to equalize the The amalgam of gold is prepared in the gilding, and to push the remaining manner described in the process of gild- amalgam upon those parts which appear ing by stirring, only a little less mer- less charged with it. When all the cury is used, in order to have an amal- mercury has volatilized, the gilding has gam about as hard as wax. This amal- a dull greenish-yellow colour, resembling gam is crystalline, and a certain crack- that of boxwood; examine whether the ling sound is heard when the crystals coat of gold is continuous. Should a are crushed between the fingers. A few empty places appear, add more stock of amalgam is generally prepared amalgam, and heat the whole again. in advance, and is divided into small The next operation is scratch-brushing, balls of nearly equal size, the value of which furnishes a pale green colour, and which is ascertained from their number, requires another heating for arriving at and from the total weight of gold em- the desired shade. The reheating should ployed. These balls are kept in water, expel any remaining mercury, and probut should not remain too long without duce a fine orange-yellow colour. being used, as the different parts do not case a bright lustre is required, submit then present the same composition. The the object, with the aid of heat, to the amalgam is spread with the finger upon ormolu process already described. To a flat, hard stone, called the gilding obtain dead lustre, the object is firmly stone; and having dipped a scratch-fixed to an iron rod, by wire of the same

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metal, and smeared with a hot paste for dead gilding, composed of saltpetre, common salt, and the double sulphate of alumina and potash. The whole is heated upon a brisk charcoal fire, without draught, and moved about until the mixture dries and begins to fuse, when the article is immediately placed in a barrel half filled with water. The covering of salts dissolves, and the dead lustre appears; this operation requires a certain amount of practice. The gilding must be strong to stand the dead lustre process, especially when the first trial is not successful. The red lines left by the iron wire disappear by plunging the object into a not too diluted solution of nitric acid, or pure hydrochloric acid. Mercury gilders do not employ pure gold; what they use is previously alloyed with a certain portion of copper or silver. With the latter metal the gilding is green. Red gilding is either obtained with a dark ormolu or with the green for red, already mentioned.

Gilding with a partly Dead, partly Bright Lustre.-1. Gild those parts with the amalgam which are intended for a dead lustre, and heat, scratchbrush, and reheat to the orange-yellow colour. Then, with the battery, give a sufficiently strong gold deposit to the whole, without regard to the parts already mercury-gilt; scratch - brush all the surfaces carefully, and smear the electrogilt portions first with a thin mixture of water, glue, and Spanish white, and afterwards with a thick paste of yellow clay. After drying, cover the mercurygilt portions with the paste for dead gilding, and proceed as already described. The Spanish white, &c., are dissolved in a dilute solution of hydrochloric acid. The glued paste is to preserve the electro-gilt portions from the heat; these are again wire-brushed with all the care necessary for not scratching the dead lustre. Brushing to finish. This method will sometimes produce red spots on those places which have been heated too much, or where the coat of gold was not thick enough. 2. Gild with the amalgam, and bring

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up the dead lustre upon those portions which are to receive it, and preserve them entirely with the resist varnish. After thorough drying, cleanse the object by dipping it into acids, in the usual manner, and gild in the electro-bath. The resist varnish stands all these acids and solutions. When the desired shade is obtained, dissolve the varnish with gasoline or benzine, which, unless there has been friction applied, does not injure either the shade or the velvety appearance of the dead lustre. Wash in a hot solution of cyanide of potassium, then in boiling water, and allow to dry naturally. The resist varnish may also be removed by allowing the object to remain for a time in concentrated sulphuric acid at 66° Baumé, which has n action whatever upon the gilding. In this case, washing with cyanide is unnecessary, pure water is sufficient. Gilding with a dead lustre, whatever process is employed, only suits those objects which will never be subjected to friction. Even the contact of the fingers injures it. A new freshness is imparted to old dead gildings by a washing in caustic lye, and then in a dilute solution of nitric or sulphuric acid. This process removes dirt, grease, dust, and smoke, but will not remedy scratches. In the latter case, the objects must be scratchbrushed, and then heated with the composition for a dead lustre.

Gilding Zinc with a Dead Lustre.There is no artistic bronze, whatever the elegance and delicacy of its shape, which may not be reproduced in zinc with an accuracy which often deceives a practised eye. A great many articles have a simple coating of brass, bronzed afterwards to imitate similar objects of real copper, brass, or bronze; but others are gilt by mercury, either with a dead lustre, scratch-brushed, or burnished. With tin solder fill all the holes and the smallest defects which may exist in the zinc object, and, at the same time, remove all seams, burrs, and rough spots. Afterwards, scour the piece by passing it, for a few seconds only, through a boiling solution of 100 parts of water and 5 or 6 parts of caustic soda; if

left too long in this caustic lye it will spoil the polish of the zinc, which dissolves. After this scouring the object is rinsed in fresh water. It is then steeped for half a minute in a pickle composed of 1 part of sulphuric acid, and 10 parts of water, and lastly rinsed in boiling water. Then place the object in a cold or warm electro-bath of copper or brass, for a few moments, until it is covered with a thin metallic coating, which is deposited very uniformly if the object has in it no tin solder, and is perfectly cleansed; the deposit is black and dull on those parts which have been soldered, or imperfectly cleansed. In this case, thoroughly scratch-brush the article, and dip again into the electrobath until the deposit is sufficiently thick. Most gilders use a warm bath for the first coating, scratch-brush, and complete the deposit in a cold bath. If a bright gilding is desired, the article may be rinsed in fresh water, and then dipped into an electrogilding bath.

"Dead Lustre Gilding, equal in appearance to the best mercury gilding, is obtained-1. With silver. An electrosilvering bath is prepared by dissolving in 2 gallons of water, 54 oz. of fused nitrate of silver, and adding 9 oz. of pure cyanide of potassium; this at first produces an abundant precipitate, which soon dissolves. The filtered liquid is the silver bath, in which is steeped the zinc article previously coated with copper or brass. Under the influence of a proper electric current, the silver deposited is of a handsome frosted dead lustre appearance, and perfectly white. The object is then rapidly and thoroughly rinsed, and dipped into an electrogilding bath, of which we shall give the composition. The dead gilding by this process is very fine and silky, but is soon darkened by the sulphuretted hydrogen of the atmosphere and of gaslight, which sulphurizes the silver through the thin film of gold. 2. The galvanoplastic process is both more durable and more economical than that with silver. Add to the necessary quantity of water, one-tenth of its volume of sulphuric acid; in this dissolve as much sulphate

of copper as it will hold at the ordinary temperature. This solution will mark from 20° to 24° Baume, then add enough water to reduce its specific gravity to 16° or 18°. This galvanoplastic bath is generally held in large vessels of stoneware, slate, wood, or gutta-percha; and porous shells are immersed in it, filled with a weak solution of sulphuric acid and of amalgamating salts. Plates or cylinders of zinc are put into these cells, and are connected by binding screws with one or more brass rods, which rest upon the sides of the trough, and support the articles which are to receive a dead lustre in this bath. The articles of zinc, previously coated with copper or brass, suspended to the rods, remain in the solution of sulphate of copper until they have acquired a satisfactory dead lustre. A few seconds after the articles have been placed in the bath, withdraw and examine them carefully; should the previous coat of copper or brass be insufficient to resist the corroding action of the acid solution of sulphate of copper, there is produced a muddy dark deposit, which is easily removed with the finger. Should this occur, the object must be scratch-brushed and placed again in the former alkaline baths of copper or brass, in order to increase the deposit which protects the zinc in the galvanoplastic bath. When the galvanoplastic dead lustre is successful, the deposit is perfectly regular, and of a pink shade which possesses great freshness. When it is irregular, marbled, crystalline, of a vinous or fire-red colour, and dull or earthy in appearance, these defects are due to the following causes; either the bath is in a bad state of conductibility or of saturation; or the surface of the zincs is too large in proportion to that of the objects, and therefore too much electricity is given out; or the previous electro-deposits of copper or brass were insufficient or inferior in quality. The remedy for either of these inconveniences is easily found out, and only requires a little care and attention. The galvanoplastic dead lustre being satisfactory, two preliminary operations are needed to ensure the success of the

gilding. They consist in rapidly passing | the object, after rinsing, through a solution made of water, 2 galls.; nitrate of binoxide of mercury, of an oz.; sulphuric acid, of an oz.; then, after rinsing, place it in another solution composed of water, 2 galls.; cyanide of potassium, 14 oz.; nitrate of silver, 31 oz. The object acquires a slightly white tinge in this liquor, and is again rinsed in fresh water, before being put into the following gilding bath;-Distilled water, 2 galls.; phosphate of soda, 21 oz.; bisulphite of soda, 31 oz. ; cyanide of potassium, pure, of an oz.; chloride of gold, neutral, of an oz. The mode of preparation of this bath is given in the receipt for hot gilding bath. This bath should be nearly boiling, and worked with an intense galvanic current. The anode is a platinum wire, which, more or less immersed in the liquor, allows of the regulation of the amount of electricity according to the volume, weight, and surface of the object to be gilt. This gilding requires an energetic electric action at the beginning; this is obtained by steeping the platinum wire deeply in the liquid, to have the entire surface of the piece covered instantaneously; as the thickness of the deposit increases, the anode is gradually removed from the bath until it only dips in a little. The gilding by this method has a remarkable freshness of tone. Before using the bath with battery, the zinc articles may be passed through a preparing bath; this is the same as a gold bath for dipping. Or the gilding may be done in two operations. After having deposited about half of the gold intended for the object, remove it from the bath, wash, pass again through the mercurial solution, and replace in the gold bath for finishing the gilding. After gilding, the articles are rinsed in clear boiling water for a few seconds to remove any saline matters; they are then dried in the stove, or in warm saw-dust of firewood. All friction should be carefully avoided, so as not to scratch the dead lustre. When parts of this gilding are burnished, their colour is

green if the frosted surface has been obtained in the silver bath, and red if the galvanoplastic bath has been employed. These inconveniences are remedied by dipping the burnished article, for a short time, into the gold bath, this last deposit of gold must be so thin as not sensibly to impair the brightness of the burnished parts. Dead lustre electrogilding upon zinc will only suit such objects as have no friction to bear, and which are not often handled; it is especially useful for clocks and similar articles, which remain under glass. The dead lustre gilding here described can be applied to all metals and alloys, provided that those corroded by the solution of sulphate of copper be previously coated with copper or brass; these previous coatings are always desirable, as they prevent crystalline and irregular deposits often formed upon metals which are not corroded by the bath of sulphate of copper. The galvanoplastic dead lustre upon copper is much finer when the pieces have been previously covered with copper or brass in the alkaline baths. Faded gildings may be renovated by dipping them into a weak tepid solution of cyanide of potassium, and afterwards into very dilute nitric or sulphuric acid. Imperfect gildings may be removed by inverting the poles in a solution of cyanides, connecting the gilt articles with the positive pole, carbon or copper, and the negative pole, zinc, with the anode which becomes gilt. This process is employed for removing the gold from articles of iron, steel, and silver, which cannot be submitted to the ungilding bath. Silver, copper, and brass may also be removed by similar processes.

Dissolving Gold from Gilt Articles.Iron and steel articles are ungilt, without any injury to themselves, by dipping them into a bath of 10 parts of cyanide of potassium and 100 parts of water, and connecting them with the positive pole of a battery. A wire or foil of platinum is fixed to the negative pole. This is inverting the position of the poles; and in this case the gold applied upon the iron or steel is dissolved in the

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