when dissolved in turpentine, it becomes a useful substance for giving deep and spirited touches to drawings.

White Colours.

Flake White is corbonate of lead, formed by corroding lead with vegetable acids, or vinegar.

White-lead is the same colour as flake white, only of an inferior quality. It is the only white used in oil-painting, and is a very useful colour; but in water it always turns black, and should never be used.

Pure carbonate of lime is very useful as a white in water-colours, as it stands perfectly well.

Egg-shell white, and oyster-shell white, are only egg-shells, or oyster-shells calcined, by which the animal gluten is destroyed, leaving the lime behind, which soon attracts the carbonic acid again from the atmosphere. Well washed Spanish white, or common whitening, answers the same purpose.

Black Colours.

Lamp black is the soot of oil, collected after it is formed by burning. It is very generally used, both in oil and water, and stands perfectly well.

Ivory black is the coal of ivory or bone, formed by giving them a great heat, while they are deprived of all access of air. It is of a more intense black than lamp black.

Blue black is the coal from burning vine-stalks in a close vessel. It is like ivory black, with a tint of blue.

Indian ink has been already described in page 346.

OF ENGRAVING.

Engraving, or graving, as it is sometimes called, is the cutting lines upon a copper-plate, by means of a steel instrument, called a graver.

This was the first way of producing copper-plate prints that was practised, and is still much used in historical subjects, portraits, and in finishing land

scapes.

The tools necessary for this art are, gravers, a scraper, a burnisher, an oil-stone, a sand-bag, an oil-rubber, and some good charcoal.

The gravers are instruments of tempered steel, fitted into a short wooden handle. They are of two sorts, square and lozenge: the first is used in cutting very broad strokes, the other for fainter and more delicate lines.

The scraper is a three-edged tool, for scraping off the burr raised by the graver. Burnishers are for rubbing down any lines that are too deep, or burnishing out any scratches or holes in the copper: they are of very hard steel, well rounded and polished.

The oil-stone is for whetting the gravers, etching-points, &c.

The sand-bag, or cushion, is for laying the plate upon, for the conveniency of turning it round in any direction.

The oil-rubber and charcoal are for polishing the plate when necessary.

As great care is required to whet the graver nicely, particularly the belly of it, the two angles of the graver which are to be held next the plate, must be laid flat upon the stone, and rubbed steadily, till the belly rises gradually above the

plate, so as that, when you lay the graver flat upon it, you may just perceive the light under 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. In order to this, keep your right arm close to your side, and place the fore-finger of your 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 your 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 exceedingly sharp point, which you may try upon your thumb-nail.

When the graver is too hard, as is usually the case when first bought, and which may be known by the frequent breaking of the point, the 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, till the steel changes to a light straw colour; then put the point into oil, to cool; or hold the graver close to the flame of a candle, till it be of the same colour, and cool it in the tallow; but be careful either way, not to hold it too long, for then it will be too soft; and in this case the point, which will then turn blue, must be tempered again. Be not too hasty in tempering; for sometimes whetting will bring it to a good condition, when it is but a little too hard.

To hold the graver, cut off that part of the handle which is upon the same line with the belly, or sharp edge of the graver, making that side flat, that it may be no obstruction.

Hold the handle in the hollow of your hand; and, extending your fore-finger towards the point, let it rest on the back of the graver, that you may

guide it flat and parallel with the plate. Take care that your fingers do not interpose between the plate and the graver; for they will hinder you from carrying the graver level with the plate, and from cutting your strokes so clean as they ought to be.

To lay the design upon the plate, after you have polished it fine and smooth, heat it so that it will melt virgin-wax, with which rub it thinly and equally over, and let it cool. Then the design which you lay on must be drawn on paper, with a black-lead pencil, and laid upon the plate, with its pencilled side upon the wax; press it down, and with a burnisher go over every part of the design, and when you take off the paper, you will find every line upon the waxed plate which you drew with the black lead pencil; then with a sharp pointed tool trace all your design through the wax upon the plate, and you may then take off the wax, and proceed to work.

Let the table, or board you work at, be firm and steady; upon which place your sand-bag with the plate upon it; and, holding the graver as above directed, proceed in the following manner.

For straight strokes, hold your plate firm upon the sand-bag with your left hand, moving your right hand forwards; leaning lighter where the stroke should be fine, and harder where would have it broader.

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For circular or crooked strokes, hold the graver stedfast, moving your hand or the plate, as you see convenient.

Learn to carry your hand with such dexterity, that you may end your stroke as finely as you began it; and if you have occasion to make one part deeper or blacker than another, do it by de

grees; and that you may do it with greater exact ness, take care that your strokes be not too close nor too wide.

In the course of your work scrape off the roughness which arises, with your scraper; but be careful, in doing this, not to scratch the plate; and that you may see your work properly as you go on, rub it with the oil-rubber, and wipe the plate clean, which will take off the glare of the copper, and show what you have 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, or charcoal.

Having thus attained the use of the graver, according to the foregoing rules, you will be able to finish the plece you had etched, by graving up the several parts to the colour required; beginning, as in the etching, with the faintef parts, and advancing gradually with the stronger, till the whole is completed.

The dry point or needle (so called because not used till the ground is taken off the plate) is principally employed in the extremely light parts of water, sky, drapery, architecture, &c.

To prevent any obstruction from too great a degree of light, the use of a sash, made of transparent, or fan paper, pasted on a frame, and placed sloping at a convenient distance between your work and the light, will preserve the sight; and when the sun shines, it cannot possibly be dispensed with.