The early painters in oil appear to have proceeded in the manner of water-colour drawing; - beginning to sketch in on a white ground, and producing their effects with transparent colours - embossing their lights with opaque tints and body colours: hence much of their freshness, and hence it has been imagined, not without apparent reason, that they commenced their works or sketched in their designs in water-colours. This is evidently contrary to the genera] mode of modern practice among the best colourists from the time of the Venetians, who are supposed sometimes to have employed the above method but generally commenced upon coloured grounds with opaque colours, and finished by glazing with such as are transparent. In the prevailing method of artists there is, however, occasional combination of both the above methods, by alternately painting and glazing throughout the progress of their works.

In the infancy, and for some time after the invention, of oil painting,* expressed oils of a drying quality appear to have been used in a simple state, or with the mere addition of substances to assist their drying, or the sole preparation of boiling or fattening. Such vehicles would undoubtedly give to pictures great strength and durability; but it unfortunately happens, that precisely iii proportion to the natural strength and power of drying in oils, is their propensity to acquire colour and become dark by age and seclusion from light; hence one principal cause of the various changes, additions, and compositions of these vehicles, by which the stronger and more drying oils of linseed, etc. have in the practice of the artist sometimes given place to the paler and weaker oils of nuts and poppy, which dry with more difficulty, yet ultimately also acquire murky colour in proportion to the body in which they are applied, but of a less offensive hue than that of linseed. Even olive oil, which is almost wholly destitute of drying power, but is not subject to acquire colour or lose its transparency, is said to have been substituted in the climate of Italy in place of the desiccative oils, but was more probably resorted to as a diluent, like the volatile essential oils of turpentine, lavender, etc, which, though destitute of strength, dry rapidly and do not change colour, and, by attenuating the drying oils, preserve in some measure their colour in painting, in proportion as they lower their strength. Of these essential oils, that commonly called spirit of turpentine, employed by painters, is a very useful addition to those of iinseed, etc. for preserving the purity of light and bright pigments from the change of colour to which all drying oils are variously subject. As, however, the essential oils thus introduced weaken the body of the vehicle and occasion it to flow, so that the colours used therewith will not keep their place, and render the touch of the pencil spiritless and uncertain, they gave occasion for the introduction of resins and balsams, which give body to oils and varnishes; and the employment of resins introduced spirituous solvents. To these have been added bees' and myrtle wax, aqueous liquids, gums, glues, starch, soaps, and salts, as media for uniting them with oils, and a variety of dryers and other substances, too numerous to mention, with which oils, etc have been compounded under the appellations of macgilps, gumtions, Venetian processes, and in the various empiricism of vehicles with which practice has been confounded, in endless mixture and mystery.*

* We speak here of the re-invention or improvement ' painting in oil by Van Eyck, or John of Bruges, about the beginning of the fourteenth century; for it is hardly to be sup-poaed that this process was not much more antient, and had merely fallen into disuse. Vitruvius, indeed, assorts that was employed by the Greeks and Romans in works exposed to weather; and we have it upon record, that in the early lime of Grecian art Protogenes had been bred a ship-painter; the very existence of which art almost proves the use of oil or varnish therein, capable of protecting colours from the action of water, which wax alone could hardly accomplish. That flax was known to the antient Egyptians, and linseed used by them as food, we have the testimony of Plutarch, in his treatise of " Isis and Osiris"- - we infer, therefore, that its oil must have been known to the Greeks and Egyptians, who could not hi suck case but have been acquainted with it* drying property in climates like theirs. We arc indeed loo apt to imagine than things to be of recent invention, of which we have neither tradition nor history.

With regard to later times, Walpolc and others have related proofs of the existence of oil-painting in Britain long previously to Van Eytk: and the question has been widely investigated by Raspe in a treatise "On the Discovery of Oil Painting." 4to 1781. The question is, however, of little importance. The Van Eycks had probably the merit of improving and extending the use of oils and varnishes in painting, rather than the invention of the entire process. much of which must have been known from the earliest times of the art.

* Tbere is hardly any bound to the variety of substances which artists have introduced into their vehicles with the hope.

It is evident that amid such complicated confusion there can be no certainty of result, that the powers of chemistry are in arms, and that in such an intestine war of vehicles the best colours may be compelled to fly. In such a state of things, there can be no escape from failure and defeat - no hope - hut in a return to that simplicity which is a prime distinction of excellence in every art, and has marked the practice of the most eminent masters in painting.

Macgilp, etc. It is probable that the practice of introducing resinous and other substances into oil vehicles, arose from the expediency of varnishing out in the progress of a picture, and the rich effects produced by glazing; and, although the practice was recommended by Armenini in 1587, it does not appear to have been generally adopted by the continental painters; whence, perhaps, the stability of the earlier works in which the pure oils only were employed upon grounds which absorbed the redundance of the vehicle, whih at of improvement. The late amiable and excellent man and artist Sir William Beechey. who was unequalled in all the manipulations of the art. was a pre-eminent follower of the great Prerident of the English School in this pictorial pharmacy: not a gum, resin, or oil escaped him - the whole materia chemica was subjected to his experimental researches; nor did he disdain to employ the Galenicals of his medical advisers: and we have seen him produce the most brilliant effects with the red spirit of lavender tod tincture of rhubarb, and, although the practice is not to be recommended, it may afford a hint.