beautiful color requires much skill in the artist, to be fully brought out. When most perfect it should come from the fire quite colorless, and afterwards receive its color by the flame of a candle. Other and common reds are given by the oxide of iron, but this requires the mixture of alumina, or some other substance refractory in the fire, otherwise at a full red heat the color will degenerate into black.

To Prepare the Flux for Enamelling on Glass Vessels. Take of saturnus glorificatus, 1 lb.; natural crystal, calcined to whiteness, lb.; salt of pulverine, 1 lb. Mix them together, and bake in a slow heat for about 12 hours; then melt the mass, and pulverize the same in an agate mortar, or any other proper vessel, which is not capable of communicating any metallic or other impurity.

Take of lead and tin ashes, litharge, antimony, and sand, each 1 oz.; nitre, 4 oz.

Calcine, or melt them together; pulverize, and mix them with a due proportion of flux, as the nature of the glass may require; or take more or less of any or all of the above, according to the depth of color desired. Or, opaque or transparent enamel, 6 parts; chloride of silver, 1 to 2 parts. Blue Enamel.

Take of prepared cobalt, sand, red-lead, and nitre, each 1 oz.; flint-glass, 2 oz.

Melt them together by fire, pulverized and fluxed according to the degree of softness or strength of color required.

Take of red-lead, 1 oz.; calcined iron, 1 oz.; antimony, 2 oz.; litharge, 2 oz.; zaffre, 1 oz.; sand, 2 oz.

Calcine, or melt together, or use raw, as may be most expedient; or vary the proportions of any or all the above, as tint or quality may require. Mode of Application.

The preceding colors may be applied to vessels of glass in the following manner, viz., by painting, printing, or transferring, dipping, floating, and grounding.

By Painting.-Mix the colors (when reduced by grinding to a fine powder) with spirits of turpentine, temper them with thick oil of turpentine, and apply them with camel-hair pencils, or any other proper instrument, or mix them with nut or spike oil, or any other essential or volatile oil, or with water, in which case use gum Arabic, or any other gum that will dissolve in water, or with spirits, varnishes, gums of every kind, waxes, or resins;

but the first is conceived to be the best.

By Printing.-Take a glue-bat, full size for the subject, charge the copper plate with the oil or color, and take the impression with the bat from the plate, which impression transfer on the glass. If the impression is not strong enough, shake some dry color on it which will adhere to the moist color; or take any engraving, or etching, or stamp, or cast, and, having charged it with the oil or color, transfer it on the glass by means of prepared paper, vellum, leather, or any other substance that will answer; but the first is the best. Any engravings, etchings, stamps, casts, or devices may be charged with waters, oils, varnishes, or glutinous matters of any kind, reduced to a proper state, as is necessary in printing in general. Any or all of these may be used alone, or mixed with the colors. When used alone the color is to be applied in powder.

By Dipping.-Mix the color to about the consistency of a cream, with any of the ingredients used for printing, in which dip the glass vessel, and keep it in motion till smooth.

By Floating. Mix the color with any of the ingredients used for printing, to a consistency according to the strength of the ground required, float it through a tube, or any other vessel, moving or shaking the piece of glass till the color is spread over the part required.

By Grounding. First charge the glass vessel with oil of turpentine, with a camel-hair pencil, and while moist apply the color in a dry powder, which will adhere to the oil; or, instead of oil of turpentine, use any of the materials used for printing; but the first is the best.

Cautions to be observed in making Colored
Enamels.
In making these enamels, the following general

cautions are necessary to be observed. 1st. That the pots be glazed with white glass, and be such as will bear the fire.

21. That the matter of enamels be very nicely mixed with the colors.

3d. When the enamel is good, and the color well incorporated, it must be taken from the fire with a pair of tongs.

General Method of making Colored Enamels. Powder, sift, and grind all the colors very nicely, and first mix them with one another, and then with the common matter of enamels; then set them in pots in a furnace, and when they are well mixed and incorporated, cast them into water, and when dry set them in a furnace again to melt, and when melted take a proof of it. If too deep

colored, add more of the common matter of enamels; and if too pale add more of the colors.

To Obtain Black Enamel with Platina. Mix some chloride of platina, dissolved in water, with neutral nitrate of mercury, and expose the precipitate, which will be formed, to a heat simply sufficient to volatilize the proto-chloride of mercury; there will be obtained a black powder, which, applied with a flux, gives a beautiful black

enamel.

To make Enamel, called Niello.

Take 1 part of pure silver, 2 of copper, and 3 of pure lead, fuse them together, and pour the amalgam into a long-necked earthenware matrass, half filled with levigated sulphur; let the mouth of the vessel be immediately closed, and the contents left to cool. The mass which results, when levigated and washed, is ready for the purposes of the artist. The cavities left by the fusion having been filled with it, the plate is to be held over

a small furnace, fed with a mixture of charcoal

and wood, taking care to distribute the enamel with the proper instrument. As soon as fusion has taken place, the plate is to be removed; and, when sufficiently cooled, is to be cleared by the file, and polished by fine pumice and tripoli.

To Paint in Enamel.

The enamel painter has to work, not with actual colors, but with mixtures, which he only knows from experience will produce certain colors after the delicate operation of the fire; and to the common skill of the painter, in the arrangement of his palette and choice of his colors, the enameller has to add much practical knowledge of the chemical operation of one metallic oxide on another; the fusibility of his materials; and the utmost degree of heat at which they will retain, not only the accuracy of the figures which he has given, but the precise shade of color which he intends to lay on.

Painting in enamel requires a succession of firings; first of the ground which is to receive the design, and which itself requires two firings, and then of the different parts of the design itself. The ground is laid on in the same general way as the common watch-face enamelling. The colors are the different metallic oxides, melted with some vitrescent mixture, and ground to extreme fineness. These are worked up with an essential oil (that of spikenard is preferred, and next to it oil of lavender) to the proper consistence of oil colors, and are laid on with a very fine hair brush. The The essential oil should be very pure, and the use of this rather than of any fixed oil, is that the whole may evaporate completely in a moderate heat, and leave no carbonaceous matter in contact with the color when red hot, which might affect its degree of oxidation, and thence the shade of color which it is intended to produce. As the

color of some vitrified metallic oxides (such as that of gold) will stand at a very moderate heat, whilst others will bear, and even require a higher temperature to be properly fixed, it forms a great part of the technical skill of the artist to supply the different colors in proper order; fixing first those shades which are produced by the colors that will endure the highest, and finishing with those that demand the least, heat. The outline and burnt in; after which the parts are filled up of the design is first traced on the enamel, ground gradually by repeated burnings, to the last and

finest touches of the tenderest enamel.

Transparent enamels are scarcely ever laid upon any other metal than gold, on account of the discopper is the metal used, it is first covered with a coloration produced by other metals. If, however,

thin enamel coating, over which gold-leaf is laid and burnt in, so that, in fact, it is still this metal that is the basis of the ornamental enamel.

To Manpture Mosaic as at Rome. of colored glass enamel; and when these pieces Mosaic work consists of variously shaped pieces are cemented together, they form those regular and other beautiful figures which constitute tessellated pavements.

The enamel, consisting of glass mixed with metallic coloring matter, is heated for 8 days in a melted enamel is taken out with an iron spoon glass-house, each color in a separate pot. The tally; and another flat marble slab is laid upon and poured on polished marble placed horizon

the surface, so that the enamel cools into the form of an inch. of a round cake, of the thickness of three-tenths

it is placed on a sharp steel anvil, called tagliulo, In order to divide the cake into smaller pieces, edged hammer is given on the upper surface of which has the edge uppermost; and a stroke of an lelopipeds, or prisms, whose bases are threethe cake, which is thus divided into long paraltenths of an inch square. These parallelopipeds are again divided across their length by the tagliulo and hammer into pieces of the length of eight-tenths of an inch, to be used in the Mosaic pictures. Sometimes the cakes are made thicker and the pieces larger.

For smaller pictures, the enamel, whilst fused, is drawn into long parallelopipeds, or quadrangular sticks; and these are divided across by the tagliulo and hammer, or by a file; sometimes, also, these pieces are divided by a saw without teeth, consisting of a copper blade and emery; and the pieces are sometimes polished on a horizontal wheel of lead with emery.

Gilded Mosaic.

Gilded Mosaic is formed by applying the goldleaf on the hot surface of a brown enamel, immediately after the enamel is taken from the furnace; the whole is put into the furnace again for a short time, and when it is taken out the gold is firmly fixed on the surface. In the gilded enamel, used in Mosaic at Rome, there is a thin coat of transparent glass over the gold.

On the Different Glazes used for Cooking Utensile.

The wrought and cast-iron vessels which are to be placed on the fire are often covered with enamel, which protects the liquid from metallic contact with the sides.

Two compositions are generally employed for this purpose, one having for its base silicate of lead, and the other boro-silicate of soda. These enamels are applied to the scoured surface of the metal in the form of a powder, which is fixed by heating it to a sufficiently high temperature to fuse

it; it then spreads over and covers the metal with a vitreous varnish.

The boro-silicate of soda enamel possesses great superiority over that of silicate of lead, for it is unattacked by vinegar, marine salt, the greater number of acid or saline solutions, even when concentrated, and resists the action of the agents employed in cooking or chemical operations.

The silicate of lead enamel is whiter and more homogeneous, which explains the preference given to it by the public, but it gives up oxide of lead to vinegar or to common salt; it acts upon a great number of coloring matters, and it is attacked by

nitric acid, which immediately communicates dull appearance to it. On evaporation the liquid leaves a white crystalline residue of nitrate of lead. This enamel is instantly darkened by dissolved sulphides, and also by cooking food containing sulphur, such as cabbage, fish, and stale eggs. It is very easy to distinguish these two enamels by means of a solution of sulphide of potas sium, sodium, or ammonium. On allowing of one of these reagents to fall on the vessel to be tested, the lead enamel darkens in a few moments, whilst the boro-silicate of soda enamel retains its white color.

To manufacture English Stoneware. Tobacco-pipe clay from Dorsetshire is beaten much in water; by this process the finer parts of the clay remain suspended in the water, while the coarser sand and other impurities fall to the bottom. The thick liquid, consisting of water and the finer parts of clay, is further purified by passing it through hair and lawn sieves of different degrees of fineness. After this the liquor is mixed (in varions proportions for various ware) with another liquor of the same density, and consisting of flints calcined, ground and suspended in water. The mixture is then dried in a kiln, and being afterwards beaten to a proper temper, it becomes fit for being formed at the wheel into dishes, plates, bowls, etc. When this ware is to be put into the furnace to be baked, the several pieces of it are placed in the cases made of clay, called seggars, which are piled one upon another, in the dome of the furnace; a fire is then lighted, when the ware is brought to a proper temper, which happens in about 48 hours, it is glazed by common salt. The salt is thrown into the furnace through holes in the upper part of it, by the heat of which it is instantly converted into a thick vapor, which, circulating through the furnace, enters the seggar through holes made in its side (the top being covered to prevent the salt from falling on the ware), and attaching itself to the surface of the ware, it forms that vitreous coat upon the surface which is called its glaze.

To make Yellow or Queensware.

This is made of the same materials as the flintware, but the proportion in which the materials are mixed is not the same, nor is the ware glazed in the same way. The flintware is generally made of 4 measures of liquid flint, and 18 of liquid clay; the yellowware has a greater proportion of clay in it. In some manufactories they mix 20, and in others 24 measures of clay with 4 of flint. The proportion for both sorts of ware depends very much upon the nature of the clay, which is very variable even in the same pit. Hence a previous trial must be made of the quality of the clay, by burning a kiln of the ware. If there be too much flint mixed with the clay, the ware, when exposed to the air after burning, is apt to crack, and if there be too little, the ware will not receive the proper glaze from the circulation of the salt

phur and other volatile ingredients which it may contain. A large earthen crucible is constructed after the exact model of an iron forge, a part of the bottom of which is filled with charcoal or cokes; these having been previously strewed with ore and about part of lime, are raised to an intense heat by a strong blast of air, introduced under the cokes at the bottom. By this heat the ore is fused, and the fluid iron drops through the fuel to the bottom; then follows the scoria, which floats upon the top of the fluid iron. This latter scoria, or, as the workmen call it, slag, is the material used in the manufacture of china, and is much impregnated with iron, and of a compact and dense structure. The slag is next let off, by a hole through the forge, into a clean earthen vessel, where it cools. This last vessel is then broken, in order to detach the slag from it, with hammers. The scoria is next pounded into small pieces and ground in water to the consistence of a fine paste, at the flint-mills of the country. This paste is then evaporated to dryness on a slipkiln, well known amongst potters. Thus evapo rated to dryness, it is used with the other ingredients in the following proportions, viz.:

Prepared iron-stone, 3 cwt.; ground flint, 4 cwt.; ground Cornwall stone, 4 cwt.; Cornwall clay, 4 cwt.; blue oxide of cobalt, 1 lb.

These having been mixed together with water by the slip-maker, are again evaporated on the slip-kiln to the proper consistency for use. The clay, thus prepared, is of course used in the usual manner in the fabrication of the several kinds of vessels.

To make Porcelain, or China. Porcelain, or china, is a semi-vitrified earthenware of an intermediate nature between commonware and glass. Chinese porcelain is composed of two ingredients, one of which is hard-stone, called petunse, which is carefully ground to a very fine powder, and the other, called kaolin, is a white earthy substance, which is intimately mixed with the ground stone.

Several compositions of mingled earth may yield a true porcelain by being burnt, and the porcelains of various countries differ in their mixtures. But the principal basis of any true porcelain is that kind of clay which becomes white by baking, and which, either by intermingled heterogeneous earth, or by particular additions, undergoes in the fire an incipient vitrification, in which the true nature of porcelain consists. Feldspar and gypsum, if added, may give that property to infusible clay.

When porcelain is to be made, the clay is prop