air furnace or an earthenware glazing oven, when the whole mass, by means of the proper temperature of fire, will be changed into a brittle resplendent and transparent glass. Enamel Flux.-1. 8 parts, redlead; 6, flint glass; 3, borax; 3, flint. 2. 7 parts, red-lead; 4, borax; 24, flint. 3. 4 parts, borax; 3, red-lead; 3, flint glass; 2, flint. 4. 3 parts, red-lead; 1, flint glass; 1, flint. Smalts.-32 parts, sand; 32, potash; 10, borax; 1, blue calx. These smalts, the materials of which are calcined in the usual manner, when finely pulverized will produce a fine rich-looking blue powder. Enamels for Porcelain Painting. The enamels, after being finely ground, should be thoroughly dried; then mixed up with turpentine, and used like other colours with a pencil; after which fused again, and vitrified by fire. Spirits of tar may be substituted instead of turpentine in all enamels, with the exception of blue and colours prepared from chrome. With regard to the burning, the lustres will bear the highest temperature of an enamelling heat; the rose colour, cornelian red, and pomona green require a less degree of heat, and are generally placed in the middle of the kiln or muffle, as well as burnish gold; other colours are not so susceptible of being destroyed by heat, and will fire in any part of the kiln or muffle. The even surface of the various coloured grounds on china is produced by first laying the space wanted with linseed oil, previously boiled with a little red-lead and a small portion of turpentine; the enamel colour is then ground fine, and dusted on the oiled part with cotton wool, or laid on with a large camel-hair pencil. The component parts of the different colours are as accurately stated as possible, but the preparation principally depends on observation, therefore experiments will be necessary that a proper judgment may be formed. when the whole mass is in a state of fusion increase the fire quickly, and there will soon be produced a fine white enamel; in the time of fusion it will be requisite to keep stirring the whole together with an iron spatula or rod. VENETIAN WHITE ENAMEL. -3 parts, flint; 3, borax calcined; 1, Cornish stone; }, oxide of tin. COMMON WHITE ENAMEL.-8 parts, flint glass; 2, red-lead;, nitre;, arsenic. BLUE ENAMELS.-For these the materials must be calcined in an air furnace or glazing oven, and caution should be observed that they are not too finely ground at the mill, in order to prevent them from crazing or chipping after being burnt on the pieces of ware. 1. 16 parts, flint glass; 5, red-lead; 2, white enamel; 2, blue calx; 1, common salt; 1, potash. 2. 16 parts, flint glass; 5, red-lead; 2, nitre; 2, potash; 2}, blue calx. BLACK ENAMELS.-Copper black is a very fine colour, the obtaining of which altogether depends upon a proper temperature of heat being applied, for nothing is more fickle and uncertain; if in the least degree overfired the colour is destroyed, and becomes of a dirty green. The other blacks are called umber blacks, and will stand any degree of heat which is required in an enamelling kiln or muffle. The umber to be highly calcined in a biscuit oven, but particular caution should be observed that it is the real Turkey umber, and not the English, which is of an inferior quality. The two first enamel blacks to be calcined in the usual way; the materials of the two latter only want grinding. ENAMEL PAINTING BLACK.-4 parts, borax; 2, umber calcined; 2, red-lead; 2, enamel blue; 1, flint; 1, blue calx. A superior black enamel is composed by uniting with 8 parts of this composition, 1 enamel; 1 enamel purple. ENAMEL PRINTED BLACK.- -1 part umber calcined; 1, borax calcined; WHITE ENAMELS.-These require the materials to be made very fine and cal-, blue calx. cined in air furnace, the heat at first COPPER BLACK ENAMEL.-1 part, cop to be generated very gradually; and per calcined; 3, enamel flux (1). RED ENAMEL.-1 part, green copperas calcined 3, enamel flux (3). The greatest difficulty in preparing red is the calcination of the copperas; calcine the copperas in a vessel exposed to the heat of an open fire, by which means it will dissipate all its volatile contents, and leave a residue of oxide of iron in powder; when it attains an orange or light red, the calcination is sufficiently accomplished; the residue is then washed repeatedly with boiling water, until the water becomes insipid and free from vitriolic acid. BROWN ENAMEL, Dark.-1 part, copperas calcined brown; 2, enamel flux (4); ,enamel flux (1). Brown enamel only requires grinding before it is fit for use; the copperas for the purpose of making dark brown will require calcining in the most intense heat of a biscuit oven; the colour of it varies according to the temperature it undergoes, first white, then orange, red, and lastly brown. Light.-1 part, umber calcined; 1, yellow under glaze;, copperas calcined red;, white enamel; 5, enamel flux (2); 3, enamel flux (3). BLUE GREEN ENAMEL.-42 parts, redlead; 15, flint; 12, borax; 22, blue vitriol calcined. To these materials, after being calcined in an air furnace or glazing oven, must be added 12 parts of white enamel, then grind them all together. flux prescribed is the only one which is susceptible of yielding its proper colour, as those fluxes which contain a large proportion of borax are very prejudicial, destroying the colour, and with the greatest difficulty forming any affinity at all, therefore should be avoided. The flux used should be highly calcined until it assumes a dark orange-coloured glass. Mix up with spirits of turpentine when dry. POMONA GREEN ENAMEL. 1 part, oxide of green chrome; 24, enamel flux (1); 1, enamel flux (4). This green is prepared by simply grinding the ingredients, and produces that dark colour equal to the French green, provided the oxide is genuine; and by adding a proportion more of flux and white enamel, there still will be a rich tint, though weaker and lighter in colour. Burnish Gold from Brown Gold.-12 parts, brown oxide of gold; 8, quicksilver; 2, oxide of silver; 1, white-lead. Put the whole of these ingredients into an earthenware mortar, and triturate them until the whole is amalgamated; the mercury being the solvent fluid, very readily combines with the rest, to which it communicates more or less of its fusibility, after which grind them very fine with spirits of turpentine. BURNISH GOLD FROM GREEN GOLD.12 parts, green gold; 7, quicksilver; 1, oxide of silver; 1, gold flux. Place the gold in an earthenware vessel on an open fire, and when heated red hot, take four times its weight of mercury, and pour it in; the mixture to be stirred with a little iron rod; the gold will be dissolved; it is then thrown into a vessel full of water until it coagulates and becomes manageable; much of the mercury is then pressed through a piece of leather, and the rest dissolved by a quantity of nitrous acid; the acid is afterwards poured off, the gold remaining is repeatedly washed with boiling water as often as needful; it is then dried and mixed up with the other ingredients, and ground with spirits of turpentine for use. PURPLE ENAMEL.-4 parts, gold in solution; 1, tin in solution. Procure a vessel to contain 50 parts of water about the temperature of blood-heat, to be well mixed with the solution of gold, and then add the solution of tin by dropping it into the menstruum, at the same time constantly stirring it with a strong feather, which will produce a fine purple-colour liquor; but it will be necessary to add a few drops of the solution of silver, which will much assist to raise the colour and beauty of the purple; to help the precipitation of the gold from its solvent (provided the precipitation does not immediately take place) add a large proportion of boiling water or a small quantity of sal ammoniac, and a, precipitate will instantly be procured; the clear liquor must then be decanted off, and the boiling water repeated until it is completely insipid. The residue consists of the oxides of gold, tin, and silver in combination, and is the only substance which has the property of communicating the purple colour to enamel glass; after the precipitate is prepared the flux must be added; the proper quantity will solely depend on the fusibility or softness of the flux, and as the operation in a great measure depends on observation, a few experiments by the operator will be found useful, independent of the accuracy of the receipt. To the purple precipitate may be added from 30 to 45, flux, enamel flux (3), according to the strength of colour intended to be made. ROSE-COLOUR ENAMEL.-3 dwts., gold in solution; 60 leaves, book silver; 2 lbs., enamel flux (1). Procure a vessel to contain 10 parts the quantity of hot water, then mix the water and gold together while the water is at the temperature of 190° F.; add pulverized sal ammoniac rather copiously, at the same time briskly stirring the mixture with a strong feather, until the appearance of a decomposition takes place, which will soon be observable by the gold being precipitated from the menstruum in the form of a fine yellow powder; when that is accomplished, let the vessel stand undisturbed a short time to allow the precipitate to subside, then decant the liquor off, and still add boiling water repeatedly to the precipitate until the water is perfectly insipid; in the next place put it on a plaster bat to dry, after which it must be mixed up with book silver and flux, according to the proportions given above, and well triturated in a mortar; then send it to the mill to be ground, when it will be in a proper state for use. This colour is supposed to be best when of a purple tinge, which may be produced by merely calcining the preparation to the heat of ignition previous to being ground; if the colour be too dark, the mixture does not possess a sufficient quantity of silver; if it is too light, the silver must have been very plentifully added, therefore the operator must add or diminish accordingly. Great caution must be observed with this receipt, as the gold precipitated by the sal ammoniac will unite with it, and then has the property of fulminating; and when gently heated or smartly struck with any hard instrument will immediately detonate; this can only be obviated by a plentiful use of boiling water; a caution which ought to be strictly attended to, as it removes the dangerous quality by depriving the gold of its salt. GOLD LUSTRE.-Take grain gold and dissolve it in aqua regia, as in the receipt for solution of gold; add 5 grains of tin; an effervescence takes place when the solution is completed and in a proper condition to be mixed; take balsam of sulphur 3 parts, spirits of turpentine 2 parts, mix them well together over a slow fire, then gradually drop the solution of gold into the menstruum, and keep stirring until the whole solution be added; provided the mixture should appear too thick, add more turpentine till of a proper consistency. 1 oz. of gold dissolved in the manner described will make upwards of 2 lbs. weight of prepared lustre, and must be used with turpentine, for all other spirits are injurious. PERSIAN GOLD LUSTRE.-Take any quantity of the precipitate of gold, first mixed with a small portion of fat oil on a flat piece of earthenware, then solution, and fire it at a strong enamelling heat, by which it will acquire a shining steel-colour lustre; then take the oxide of platina mixed up with water to a thickish consistence, and lay it on the steel lustre, and fire it again in a kiln or muffle, but not to exceed a bloodred heat; it is then called silver lustre, being less resplendent, having more solidity and whiteness, and a very similar appearance to silver. On all white earthenware the platina in solution is perfectly sufficient to produce a silver lustre. place it on a stone previously heated, | and when the mixture begins to be in an eliquated state, stir it well with a palette knife, and keep adding more oil by a little at a time, until with the continuance of a gentle heat it assumes the colour of balsam of sulphur, then add, with a less degree of heat, turpentine in small quantities. 1 oz. of the precipitate of gold will make about 1 lb., more or less, of lustre, having more solidity and opacity than the gold lustre. The proportions of the fat oil of turpentine to the spirits of turpentine, are 1 part of the former to 3 of the Bronze Gold.-2 parts, burnish latter. gold; 2, oxide of copper; 1, quicksilver; SILVER or STEEL LUSTRE.-This is, gold flux. Having dissolved the copprepared by taking platina and dissolving it in aqua regia composed of equal parts of spirits of nitre and marine acid. The solution must be placed in a sand bath, at a moderate temperature; then take 3 parts of the spirits of tar, and 1 part of the solution of platina, mixing the solution with the tar very gradually, for as soon as the combination takes place, an effervescence will arise, the nitrous acid will evaporate and leave the platina in combination with the tar. After the above process has been performed, should the menstruum be found too thin and incapable of using, set it on a sand bath as before for a few hours; the spirit of the tar will evaporate, and by that means a proper consistence will be obtained. It must be used with spirits of tar. Oxide of Platina. Dissolve platina as for silver lustre. Let the solution fall into a large vessel of water at the temperature of blood-heat; the sal ammoniac must then be added, and the precipitate will immediately descend to the bottom of the vessel in an orangecolour powder; decant off the water, and repeatedly apply to the precipitate boiling water until the water becomes quite insipid; after being gradually dried it is then used for the purpose of producing a silver lustre in the following manner :-First, procure brown earthenware of a full soft glaze, and with a broad camel-hair pencil lay on all over the piece of ware the platina in per in aqua fortis, it is again separated from its solvent and falls to the bottom of the vessel by the addition of iron; the precipitate of copper may be increased or diminished at discretion, which makes the bronze richer or poorer in colour according to the proportion of burnish gold contained in the mixture. It is chiefly used for ornamenting the handles and heads of jars, vases, and so on, and occasionally intermixed with burnish gold. Solution of Gold.-Put 40 dwts. of aqua regia in a small bottle, to which add 5 dwts. of grain gold, the solution will immediately commence, and may be observed by the effervescence which arises at the time; when the solution is complete, the whole of the gold will be dissolved, which will be accomplished in about two hours if the acids be genuine, but when they are not, it will be requisite to apply heat to assist in facilitating the solution. Solution and Oxide of Silver. 1 part of nitric acid, and 3 parts of boiling water; add one-third of its weight of silver, dilute with five times its quantity of water, then add a portion of common salt, stirring it all the time and immediately a white precipitate will fall to the bottom of the vessel; the liquor must then be decanted off and boiling water repeatedly added, until the water is quite insipid. This precipitate is the pure oxide of silver, and is the same as that used in the prepara tion of burnished gold and in staining of glass. the different particles is sufficiently destroyed. This operation will be complete in about ten hours, the weight of the re gulus being from 31 to 33 lbs.; on examin Solution of Tin.-2 parts of nitrous acid, and part of muriatic acid, with an equal part of water; adding the scoria, if there remains mixed granulated tin by small pieces at a time, so that one piece be dissolved before the next is added. This aqua regia will dissolve half its weight of tin; the solution when properly obtained is of a reddish brown or amber colour, but when gelatinous the solution is defective. Oxide of Tin.-Take any given quantity of grain tin, and granulate it by melting the tin in an iron ladle; when in fusion pour it into a vessel full of cold water, by which means the tin will be reduced into small grains or particles adhering to each other; then take a biscuit dish previously lined with flint, spread it slightly over with pounded nitre, take the granulated tin, and lay it on the dish 2 inches in thickness, adding a little more nitre on the top; 1 lb. of nitre will be sufficient to oxidate 5 lbs. of granulated tin; the dish containing the tin and nitre is to be calcined in a reverberatory furnace or glazing oven; particular attention is required in seating it, so that plenty of room remains to admit a free access of air to pass over the metal, other wise it is impossible to obtain the whole of it in an oxidated state. Balsam of Sulphur. -Take 2 parts of flour of sulphur, and 4 parts of turpentine; put them in a vessel over a slow fire until the sulphur is completely dissolved; after which add 8 parts of linseed oil, and continue the same degree of heat for about one hour; previous to becoming cold strain it through a piece of cloth. Regulus of Zaffre.-112 parts, zaffre; 57, potash; 18, charcoal. The charcoal being pulverized, and all the materials mixed up together, they are put into large-sized crucibles capable of holding from 3 to 4 quarts, and filled quite full, then placed in a strong brickbuilt reverberatory furnace, commencing with a slow fire, and continued for some time, but as soon as it is heated to a redheat, it will require a considerably stronger fire before the cohesion between with it small pieces of metal like small shot, or when pounded, if the scoria has a bluish cast, the fire has not been strong enough; there is but little danger to be apprehended from the most intense heat, provided the particles in fusion do not perforate the crucibles. At the bottom of each cake of regulus there will be bismuth slightly adhering, which is easily separated without the application of any great degree of heat, by placing the cakes upon an iron plate or pan, which will soon bring the bismuth into a state of liquefaction, and it can then be separated from the regulus. TO REFINE REGULUS OF ZAFFRE.50 parts, regulus of zaffre; 6, potash ; 3, sand; pulverize and well mix, then put in crucibles holding about 14 lb. each, and fire in a reverberatory furnace, commencing with a slow fire and gradually increase the heat for about eight hours; by that time the regulus will have fallen to the bottom of the crucible, and the scoria found at the top will be of a blackish green; it will then be necessary that another course ΟΙ refining should take place, in order that the regulus may be obtained in a more perfect state of purity. Blue Calx. -1. 30 parts, refined regulus of zaffre; 1, plaster;, borax. 2. 30 parts, refined regulus of cobalt; 1, plaster;, borax. These inaterials to be made very fine, and well mixed; put the mixture in earthenware biscuit cups 11⁄2 in. high, 3 in. in diameter, and 11⁄2 in. thick, filled nearly to the top; set them in a furnace, the fire to be increased until the mixture is in a state of fusion, the same degree of heat must be continued for about six hours afterwards, and then the fire hastily slackened; this operation will occupy from twelve to thirteen hours; at the top of the cups will be found a blue calx separated from the nickel; but as a large proportion of blue will still remain in the nickel when sunk to the bottom of the cups, |