50 parts regulus of zaffre, 6 potash, 3 sand, pulverise and well mix, then put in crucibles holding about 1 1/2 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 of refining should take place, in order that the regulus may be obtained in a more perfect state of purity.
1 part copperas calcined brown, 2 enamel flux (d), 3/4 enamel flux (a). 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.
11 parts borax, 5 1/2 litharge, 1 silver oxide. In these enamel fluxes the materials are to be made very fine, particularly the flint, and mixed well together, so that the particles may more easily concrete when in a state of fusion; then calcined in an 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.
2 1/2 parts burnish gold, 2 copper oxide, 1 quicksilver, 1/4 gold flux. Having dissolved the copper 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 heals of jars, vases, and so on, and occasionally intermixed with burnish gold.
Gold Solution. Put 40 dwt. aqua regia in a small bottle, to which add 5 dwt. 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 facilitate the solution.
12 parts brown oxide of gold, 8 quicksilver, 2 silver oxide, 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.
12 parts green gold, 7 1/2 quicksilver, 1 1/2 silver oxide, 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 is 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.
Take grain gold and dissolve it in aqua regia, as for solution of gold; add 5 gr. 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. gold dissolved in the manner described will make upwards of 2 lb. 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 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 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 latter.
42 parts red-lead, 15 flint, 12 bora, 2 3/4 blue vitriol calcined. To these materials, after being calcined in an air furnace or glazing oven, must be added 12 parts white enamel, then grind them all together.
3 2/3 parts blue green frit, 1 enamel yellow.
2 1/2 parts blue green, 1 enamel yellow.
1 part oxide of green chrome, 2 1/2 enamel flux (a), 1 1/2 enamel flux (d). 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.