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a-fresh. The plate must also be previously cleaned, with the greatest possible care, with a rag and whiting, as the smallest stain or particle of grease produces a streak or blemish in the grain. All these attentions are absolutely necessary to produce a tolerably regular grain; and, after every thing that can be done by the most exprienced artists, still there is much uncertainty in the process. They are sometimes obliged to lay on the grains several times, before they procure one sufficiently regular. The same proportions of materials do not always produce the same effect, as it depends in some degree on their qualities: and it is even materially altered by the weather. These difficulties are not to be šurmounted but by a great deal of experience; aad those who are daily in the habit of practising the art are frequently liable to the most unaccountable accidents. Indeed, it is much to be lamented, that so elegant and useful a process should be so extremely delicate and uncertain.

It being necessary to hold the plate in a slanting direction, in order to drain off the superfluous fluid, there will naturally be a greater body of the liquid at the bottom than at the top of the plate. On this account; a grain laid in this way is always coarser at the side of the plate that was held lowermost. The most usual way is, to keep the coarsest side for the fore-ground, that being generally the part which has the deepest shadows. In large landscapes, sometimes various parts are laid with dif. ferent grains, according to the nature of the subject.

The finer the grain is, the more nearly does the impression resemble Indian-ink, and the fitter it is for imitating drawings: but very fine grains have several disadvantages; for they are apt to come off before the aqua fortis has lain on long enough to produce

the desired depth; and as the plate is not corroded so deep, it soon wears out in printing; whereas coarser grains are firmer, the acid goes deeper, and the plate will throw off a great many more imprèssions. The reason of all this is evident, when it is considered, that in the fine grains, the particles are small and near each other, and consequently the aqua fortis, which acts laterally as well as down. wards, soon undermines the particles, and causes them to come off. If left too long on the plate, the acid would eat away the grain entirely.

On these accounts, therefore, the moderately coarse grains are more sought after, and answer better the purpose of the publisher, than the fine grains which were formerly in use.

Although there are considerable difficulties in laying properly the aqua tint grain, yet the corrod .. ing the copper, or biting-in, so as to produce exactly the tint required, is still more precarious and uncertain. All engravers allow that no positive rules can be laid down, by which the success of this process can be secured; nothing but a great deal of experience and attentive observation can enable the artist to do it with any degree of certainty. There are some hints, however, which may

be of considerable importance to the person who wishes to attain the practice of this art. It is evident, that the longer the acid remains on the

copper, the deeper it bites, and consequently the darker will be the shade in the impression. It may be of some use, therefore, to have several bits of copper laid with aqua tint grounds, of the same kind to be used in the plate, and to let the aqua fortis remain for different lengths of time on each ; and then to examine the tints produced in one,

two, three, four minutes, or longer. Observations of this kind, frequently repeated, and with different degrees of strength of the acid, will at length assist the judgment, in guessing at the tint which is produced in the plate. A magnifier is also useful to examine the grain, and to observe the depth to which it is bit. It must be observed, that no proof of the plate can be obtained till the whole process is finished. If any part appears to have been bit too dark, it must be burnished down with a steel burnisher ; but this requires great delicacy and good management not to make the shade streaky; and as the beauty and durability of the grain is always somewhat injured by it, it should be avoided as much as possible.

Those parts which are not dark enough must have a fresh grain laid over them, and be stopped round with varnish, and subjected again to the aqua fortis. This is called re-biting, and requires peculiar care and attention. The plate must be very well cleaned out with turpentine before the grain is laid on, which should be pretty coarse, otherwise it will not lay upon the heights only, as is necessary, in order to produce the same grain. If the new grain is different from the former, it will not be so clear nor so firm, but rotten.

We have now given a general account of the process of engraving in aqua tint, and we believe that no material circumstance has been omitted, that can be communicated without seeing the operation ; but after all it must be confessed, that no printed directions whatever can enable a person to practise it perfectly. Its success depends upon so many niceties, and attention to circumstances apparently trifling, that the person who attempts it must not be surprised if he does not succeed at

first. It is a species of engraving simple and expeditious, if every thing goes on well; but it is very precarious, and the errors which are made are rectified with great difficulty.

It seems to be adapted chiefly for imitation of sketches, washed drawings, and slight subjects; but does not appear to be at all calculated to pro. duce prints from finished pictures, as it is not susceptible of that accuracy in the balance of tints necessary for this purpose. Nor does it appear to be very suitable for book-plates, as it does not print a sufficient number of impressions. It is, therefore, not to be put in competition with other modes of engraving. If confined to those subjects for which it is calculated, it must be allowed to be extremely useful, as it is expeditious, and may be attained with much less trouble than any other mode of engraving. But even this circumstance is a source of mischief, as it occasions the production of a multitude of prints that have no other effect than that of vitiating the public taste.

Engraving in aqua tint was invented by Le Prince, a French artist, who kept his process a long time secret, and it is said he sold his prints at first as drawings; but he appears to have been acquainted only with the powder-grain and the common method of stopping-out.

The prints which he produced are still some of the finest specimens of the art. Mr. Paul Sandby was the first who practised it in this country, and it was by him communicated to Mr. Jukes. It is now practised very generally all over Europe; but no where more successfully than in this kingdom,

WOOD-CUTTING.

Wood-cutting or engraving on wood is a process exactly the reverse to engraving on copper. In the latter, the strokes to be printed are sunk, or cut into the copper, and a rolling-press is used for printing it; but in engraving on wood, all the wood is cut away, except the lines to be printed; which are left standing up like types, and the mode of printing is the same as that used in letterpress.

The wood used for this purpose is box-wood, which is planed quite smooth. The design is then drawn upon the wood itself with black-lead, and all the wood is cut away with grävers and other proper tools, except the lines that are drawn. Or sometimes the design is drawn upon paper, and pasted upon the wood, which is cut as before. This art is of considerable difficulty, and there are few who practise it. It is, however, useful for books, as the printing of it is cheaper than that of copper-plates. It cannot be applied equally well to all the purposes to which copper-plate engraving is applicable.

ETCHING ON GLASS.

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Glass resists the action of all the acids, except the fluoric acid. By this, however, it is corroded in the same manner as copper is by aqua fortis and plates of glass may be engraved in the same manner as copper.

There are several methods of performing this. We shall first describe the mode of etching by

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