with oil of turpentine, with a camel-hair pencil, || and while moist apply the colour in a dry powder, which will adhere to he oil, or, instead of oil of turpentine, use way of the materials used for print- || ing; but the first is the best.

Cautions to be observed in making coloured enamels.

In making these enamels, the following general eautions are necessary to be observed. Ist. That the pots be glazed with white glass, and be such as will bear the fire.

24. That the matter of enamels be very nicely raixed with the colours.

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

General method of making coloured enamels. Powder, sift, and grind all the colours 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 coloured, add more of the common matter of enamels; and if too pale add more of the colours.

To obtain black enamel with platina. Mix some chlorine of platina, dissolved in water, with neuter-nitrate of mercury, and expose the precipitate, which will be formed, to a heat simply sufficient to volatilize the proto-chlorine of mercury; there will be obtained a black powder, which, applied with a dissolvent or flux, gives a beautiful black enamel.—Annales de Chimie.

To make enamel, called niello.

Take 1 part of pure silver, 2 of copper, and S 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 conents 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 Jeen 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 colours, but with mixtures, which he only knows from experience will produce certain colours 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 colours, the enameller has to add much practical knowledge of the chemical operation of one metallic exide 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 colour 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 colours 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 laven

der) to the proper consistence of oil colours, and are laid on with a very fine hair brush. 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 colour when red hot, which might affect its degree of oxi dation, and thence the shade of colour which it is intended to produce. As the colour 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 techni cal skill of the artist to supply the different colours in proper order; fixing first those shades which are produced by the colours that will endure the highest, and finishing with those that demand the least heat. The outline of the design is first traced on the enamel, ground and burnt in; after which, the parts are filled up gradually by repeated burnings, to the last and finest touches of the tenderest ena mel.

Transparent enamels are scarcely ever laid upon any other metal than gold, on account of the discoloration produced by other metals. If, however, copper is the metal used, it is first covered with a 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 manufacture Mosaic as at Rome. Mosaic work consists of variously shaped pieces of coloured glass enamel; and when these pieces are cemented together, they form those regular and other beautiful figures which constitute tessellated pavements.

The enamel, consisting of glass mixed with metallic colouring matter, is heated for eight days in a glass-house, each colour in a separate pot. The melted enamel is taken out with an iron spoon, and poured on polished marble placed horizontally; and another flat marble slab is laid upon the sur face, so that the enamel cools into the form of a round cake, of the thickness of three-tenths of an inch.

In order to divide the cake into smaller pieces, it is placed on a sharp steel anvil, called tagliulo, which has the edge uppermost; and a stroke of an edged hammer is given on the upper surface of the cake, which is thus divided into long parallelo pipeds, or prisms, whose bases are three-tenths 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 horizontai wheel of lead with emery.

Gilded Mosaic.

Giided Mosaic is formed by applying the gold leaf 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 transpres rent glass over the gold.

ENGRAVING.

The different modes of engraving are the follow- ||

ing:

1. In strokes cut through a thin wax, laid upon the copper, with a point, and these strokes bitten or corroded into the copper with aqua-fortis. This is called etching.

2. In strokes with the graver alone unassisted by aqua-fortis. In this instance, the design is traced with a sharp tool, called a dry point, upon the plate; and the strokes are cut or ploughed upon the copper with an instrument distinguished by the name of a graver.

3. In mezzotinto, which is performed by a dark ground being raised uniformly upon the plate with a torthed tool.

4. In aquatinta, the outline is first etched, and afterwards a sort of wash is laid by the aqua-fortis upon the plate, resembling drawings in Indian ink, bistre, &c.

5. On wood, performed with a single block. 6. On wood, with two, three, or more blocks. This mode of engraving is called chiar' oscuro, and was designed to represent the drawings of the old masters.

7. Engraving on steel.

Etching.

Etching is a method of working on copper, wherein the lines or strokes instead of being cut with a graven, are eaten with aqua-fortis.

Materials, &c.

and breadths of the shadows till the marks of them appear upon the ground, taking care not to penetrate it by tracing too hard.

As great nicety is required in this part of the work, it will be necessary now and then to lift up one corner of the original, and examine whether every part be traced before the taking it off, as it will be extremely difficult to lay it down again in its former position. Directions for etching.

Having carefully traced the original, take it off, and lay a silk handkerchief next the plate, and over that the etching board; then proceed to the etching; for which, observe the following directions.

Distances in landscapes, or the faint parts of any other picture, are the first to be done: and these are to be worked closer, and with a sharper pointed needle: the darker parts must be etched wider, and with a blunter needle; but to prevent mistakes, the needles may be marked according to their different degrees, and the uses for which they are intended. As for the very faintest parts of all, they are to be left for the graver, or dry needle.

In buildings, and all architecture in general, use a parallel rufer, till frequent practice enables the artist to do them well enough without.

The needles may, when necessary, be whetted upon the oil-stone, keeping them turning in the hand, so as to whet them equally all round. The The principal materials for this art are, the cop- oil-stone will be further useful in whetting the per-plate, hard and soft ground, (the first for win-scraper, which is to be rbbed flat upon the stone, ter, and the other for summer,) a dabber, turpen- and with a steady hand, keeping oil constantly upon tine-varnish, lamp-black, soft wax, and aqua-fortis. the stone. The tools are an oil-rubber, a burnisher, a scraper, a hand-vice, etching-boards, etching-needles, an oil stone, and a parallel ruler.

To lay on the ground or varnish.

is

Then inclose the work with a rim or border of soft wax, about half an inch high, bending the wax in the form of a spout, at one corner, to pour off the aqua-fortis; take care to lay the wax so close to the plate that no vacancies be left.

To bite or eat in the work with aqua fortis. Examine the work carefully and see that nothing omitted; and if any scratches appear upon the ground, or mistakes be committed, stop them out, Having provided a plate of the size of the draw-by covering them with a mixture of lamp-black ing intended to be copied, rub it well with an oil- and varnish, laid on thinly with a hair-pencil, rubber made of swan-skin flannel, till all the marks which, when dry, will resist the aqua-fortis. I of the charcoal used in polishing it, entirely disap- will be better, however, to stop these out, as they pear; then, wipe off the dirty oil with a linen rag, occur in the course of the work, as they will dip the finger in some clean oil, and touch it over be less liable to escape notice; when the varnish is every part of the plate; after which, with the bur-dry, etch it over again if required. nisher, polish the plate; and in case any sand-holes or flaws appear, the scraper will assist in taking them out. The marks left by the scraper are to be taken out by the burnisher till nothing appear. Having fixed the hand-vice at one end of the plate with a rag and whiting, clean the plate carefully from grease; then heat it over a charcoal fire, or lighted paper, lay the ground on thinly, and dab it all over with the dabber, till it is perfectly smooth and even; then warm the plate again, and, holding it up with the ground downwards, smoke it all over with a wax candle, taking care that the snuff of it does not touch the ground, and wave the candle continually over every part, so that the ground may not be burnt by heating it more in one place than nother. If the plate be large, bind four wax-taners together.

To trace the outlines.

The aqua-fortis must be single; and if too strong, as will be seen in the biting, take it off, and mix it with a little water, shaking them together in a bottle; and when, by often using, it becomes too weak, it may be strengthened by mixing it with a little double aqua-fortis. The bottle which contains the aqua-fortis, should have a large mouth and a glass stopper.

Let the aqua-fortis lie on the plate a short time, wiping off the bubbles as they arise with a feather, which may remain upon the plate while it is biting; after which take it off, and wash the plate with water; then let it dry, and by scraping off part of Rub the back part of the drawing all over with the ground from the faintest part of the work, try a bit of rag or cotton, dipt in the scrapings of red if it be bit enough; and if not, stop cut the part chalk, and shake off the loose dust, or wipe it off which has been tried with the lamp-black and var gently with a clean rag. Place the red side uponnish, and when that is dry, pour on the aqua-forti the plate, making it fast at each corner with a little bit of soft wax. Lay the etching board under the hand, to prevent bruising the ground; then with blunt etching needle trace lightly the outlines

again.

When the faint parts of the work are bit enough, stop them out, and proceed to bite the stronger parts, stopping them out as occasion requires, ti?

the whole work is sufficiently bit; then warm the above directed, proceed to business in the follow plate, and take off the soft wax: after which, heating manner:the plate til! the ground melts, pour on a little oil, For straight strokes, hold the plate firm upon the and wipe the whole off with a rag. When the sand-bag with the left hand, moving the right hand ground is taken off, rub the work well with the oil-forwards, leaning lighter where the stroke should rubber, and wipe the plate clean; then proceed to be fine, and harder where it should be broader. minish it with the graver. For circular or crooked strokes, hold the graver steadfast, moving the hand or the plate as most convenient. Carry the hand with such a sleight, that the stroke may be ended as finely as it was be gun; and if there is occasion to make one part deeper or blacker than anotner, do it by degrees, taking care that the strokes be not too close nor too wide.

Engraving tools.

The tools necessary for engraving, are the oilrubber, burnisher, scraper, oil-stone, needles, and ruler, already mentioned to be used in etching; also gravers, eompasses, and a sand bag.

Gravers are of two sorts, square and lozenge. Three of each sort should be provided. The first is used in cutting the broader strokes, the other In the course of the work, scrape off the bur or for the fainter and more delicate ones. No roughness which arises with the belly of the gravgraver should exceed the length of five inches ander, but be careful in doing this, not to scratch the

a half, the handle included, excepting for straight lines.

The sand-bag or cushion is used to lay the plate on, for the convenience of turning it about.

To whet and temper the graver.

plate; rub it with the oil rubber, and wipe the plate clean, which will take off the glare of the copper, and shew what has been done to the best advantage. Any mistakes or scratches in the plate may be rubbed out with the burnisher, and the part levelled with the scraper, polishing it again afterwards lightly with the burnisher.

As great pains are required to whet the graver nicely, particularly the belly of it, care must be taken to lay the two angles of the graver, which The piece may now be finished by graving up are to be held next the plate, flat upon the stone, the several parts to the colour of the original, beand rub them steadily, till the belly rises gradual-ginning, as in etching, with the fainter parts, and ly above the plate, so that when the graver is laid advancing gradually with the stronger, till the whole flat upon it, the light may be just perceived under is completed. the point, otherwise it will dig into the copper, and then it will be impossible to keep a point, or execute the work with freedom. Keep the right arm close to the side, and place the forefinger of the left hand upon that part of the graver which lies uppermost on the stone. When this is done, in order to whet the face, place the flat part of the handle in the hollow of the hand, with the belly of the graver upwards, upon a moderate slope, and rub the extremity or face upon the stone, till it has an exceeding sharp point. The oil-stone, while in use, must never be kept without oil.

The dry needle (so called because not used till the ground is taken off the plate) is principally employed in the extreme light parts of water, sky, dra|| pery, architecture, &c.

To prevent too great a degree of light, use a sash, made of transparent or fan paper, pasted on a frame and placed sloping at a convenient distance between the work and the light.

To engrave upon copper in alto relievo. The new art of engraving upon copper, which Mr Lizars of Edinburgh has invented, is a substitute for wood engraving, in the same manner as lithography is a substitute for copper-plate engratheving; but while Mr Lizars has given us a cheaper art for a more expensive one, he has also given us a more perfect art for one which is full of imperfections.

When the graver is too hard, which may be known by the frequent breaking of the point, method of tempering it is as follows:

Heat a poker red-hot, and hold the graver upon it within half an inch of the point, waving it to and fro till the steel changes to a light straw colour; In the common operation of engraving, the dethen put the point into oil to cool; or hold the sired effect is produced by making incisions upon graver close to the flame of a candle till it be of the copper-plate with a steel instrument of an anthe same colour, and cool it in the tallow; but be gular shape, which incisions are filled with printcareful either way not to hold it too long, for thening ink, and transferred to the paper by the presit will be too soft; and in this case the point, which will then turn blue, must be broken off, whetted afresh, and tempered again if required.

To hold the graver.

Hold the handle in the hollow of the hand, and extending the fore-finger down towards the point, let it rest upon the back of the graver, so as to hold it flat and parallel with the plate.

Take care that the fingers do not interpose beween the plate and the graver, for they will prevent the artist from carrying the graver level with the plate, and from cutting the strokes so clean as they ought to be.

To lay the design upon the plate. After polishing it fine and smooth, heat it so that it will melt virgin war, with which rub it thinly and equally over, and let it cool. Then the design must be drawn on paper with a black lead pencil, and laid upon the plate with its pencilled side upon the wax; press it to, and with a burnisher go over every part of the design; then with a sharp-pointed tool, trace it through the wax upon the plate, take off the wax and proceed to work.

sure of a roller, which is passed over its surface. There is another mode of producing these lines or incisions by means of diluted nitrous acid, in which the impression is taken in the same way. Mr Lizars' new method of engraving is done upon a principle exactly the reverse, for instead of the subject being cut into the copper, it is the interstice between the lines which is removed by diluted aqua-fortis, and the lines are left as the surface: from which the impression is taken by means of a common type printing press, instead of a copper-plate press.

This is effected by drawing with common turpentine varnish, covered with lamp-black, whatever is required upon the plate, and when the varnish is thoroughly dry, the acid is poured upon it, and the interstice of course removed by its action upon the uncovered part of the copper. If the subject is very full of dark shadows, this operation will be performed with little risk of accident, and with the removal of very little of the interstice between the lines: but if the distance between the lines is great, the risk and difficulty is very much increased, and it will be requisite to cut away the parts which surround the lines, with a graver, in order to prevent the daboer with the printing ink frem reaching

the bottom, and thus producing a blurred impression. It is obvious, therefore, that the more the plate is covered with work, the less risk will there be in the preparation of it with the acid, after the subject is drawn, and the less trouble will there be in removing the interstice (if any) from those places where there is little sharing.

To make bordering wax for copperplates. Take one-third of bees wax, and two-thirds of pitch: melt them in a pipkin or iron ladle, and pour them into luke-warm water. When well mixed, and the water is squeezed out, form it into rolls of convenient size.

When wanted for use, it must be put into lukewarm water to soften it, and render it easily worked by the nand. When sufficiently pliable, it must be drawn out into long rolls, and put round the edges of the plate, from half an inch to an inch high. Mould a spout at one corner to pour off the aqua-fortis.

Another method.-Melt bees-wax with a small portion of Venice turpentine and tallow, until it becomes of a proper consistency.

This is used for placing round the plate about an inch high, previously to pouring on the aquafortis. At one corner a spout or gutter should be made for the purpose of pouring off the aqua-fortis, when the etching is sufficiently bit in.

Salmon's soft varnish.

Take of virgin-wax, four ounces, asphaltum, two ources, amber and mastic, each one ounce.

The preparation is much the same as for the preceding, only caution should be used that the fire be not too strong, as the varnish will, otherwise, be apt to burn. This varnish is only for summer use, and would be too hard for winter.

Excellent Parisian soft varnien.

Take of virgin-wax, and of asphaltura, or Greek pitch, each one ounce; of black pitch, half an ounce, and of Burgundy pitch, a quarter of an ounce. The asphaltum must be pounded in a mortar, and the wax melted over a slow fire, in a pot of glazed earthenware; and the rest of the ingredients added little by little, stirring the mixture accordingly, till the whole be well melted and incorporated; and taking care that the matter be not suffered to burn. Afterwards throw the whole mass into an earthen vessel full of clean water, and knead it with the hands, to form it into little balls; and then roll them up in new strong taffety for use.

Another soft varnish.-Take of virgin-wax, two ounces and a half, of Burgundy pitch, three ounces, of resin, half an ounce, asphaltum, two ounces, and turpentine, one penny-worth: this varnish is very good, and well approved. The preparation is the same as that of those already given.

Lawrence's soft varnish.

bending it double three or four times, betwixt the fingers; the varnish being then enough boiled, must be taken off the fire, and having been suffered to cool a little, must be poured into warm water, that it may work the more easily with the hands, so as to be formed into balls, which must be wrapt in taffety for use.

To make Rembrandt's white varnish for engraving. Take of virgin-wax, one ounce, of mastic, half Take of virgin-wax and asphaltum, each two an ounce, of calcined asphaltum, or of amber, half ounces, of black pitch and Burgundy pitch, each an ounce. Pound the mastic and asphaltum sepa- half an ounce. Melt the wax and pitch in a new rately in a mortar; put the wax into a new earthen-earthen-ware glazed pot, and add to them, by deware pot well glazed, and place it over a fire, till grees, the asphaltum finely powdered. Let the the wax be melted; then sprinkle in, by little and whole boil till such time, as that taking a drop little, the mastic and asphaltum, and stir the mix-upon a plate, it will break when it is cold, on ture well together till the whole be incorporated. Pour the melted matter afterwards into clean water, and form it into a ball which must be kept for use. In using this varnish, it is proper to take particular care of three things. The first, not to heat the plate too much when the varnish is put upon it. The second, to lay the first coat of varmsh as thin as possible, in order to be able to spread the white varnish upon it, without rendering the whole of too great a thickness: The third, to omit blackening this varnish with smoke, as is done with the common; but when it is become entirely cold, take a piece of white lead, and having ground it extremely fine, temper it with gum water; and then, with a pencil, lay a coat of it very thinly and equally over the whole plate. This is the manner in which Rembrandt varnished his plates.

Callot's soft varnish.

Take of virgin-wax, four ounces, of amber, (or of the best asphaltum calcined), and of mastie, each two ounces, of resin, common pitch, or shoemaker's wax, each one ounce, and of varnish, or turpentine, half an ounce.

It must be observed, first, that the fire be not toc violent, for fear of burning the ingredients; a slight simmering will be sufficient: 2dly, that while the asphaltum is putting in, and even after it is mixt with them, the ingredients should be stirred coutinually with a spatula; and Sdly, that the water, into which this composition is urown, should be nearly of the same degree of warmth with it, to prevent a kind of cracking that happens when the water is too cold.

The varnish ought always to be harder in summer than in winter, and it will become so, if it be suffered to boil longer, or if a greater proportion of the asphaltum or brown resin be used.

To apply soft varnish to copper plates. The plate being well polished and burnished, Having prepared all these ingredients, take a also cleansed from all greasiness, by chalk or Spanew earthen-pot, and put it over the fire, with the nish white, put it upon a chafing-dish, in which virgin-wax in it; and when that is melted, add gra- there is a moderate fire, observing to hold it so that dually to it the pitch; and afterwards the powders, it may not burn. It is to be left over the fire, till stirring the mixture each time in proportion to the it be so hot that the varnish, being brought in conaddition made to it. When the whole is sufficiently tact with it, may melt. Then take some of the melted and mixt together, take the pot from the soft varnish well wrapt up in taffety, that is free fire, and having poured the mass in an earthen ves- from all grease and dirt, and also strong and sound sel, full of clean water, form it into balls, by work-in every part. With this rub the plate, fixed over ing it with the hands, and keep them in a box, free from dust, for use.

the fire till it grow hot. In doing this, it should be gently passed from one side to the other in a right line, so as to form several rows, till the plate be every where moderately covered. After this, with a sort of ball made of cotten, tied up in taffety, beat every part of the plate gently, while the var. nish is yet in a fluid state; and to unite it still more and give it a finer grain, it is proper take the