s a method of painting in relief on walls. It is performed with water-colours on fresh plaster, or on a wall laid with mortar not yet dry. This species of painting has a great advantage by its incorporating with the mortar, and drying along with it; thus becoming very durable, and capable of resisting the weather. The Italians, from whom we borrow the term, call it fresco, because it is frequently used for walls, alcoves, and other buildings in the open air. Vitruvius, lib. vii. cap. 4, calls it udo teortico.

Painting in fresco is a very ancient art, having been practised in the earliest ages of Greece and Rome. It is chiefly performed on walls and vaults newly plastered with lime and sand; but the plaster is only to be laid in proportion as the painting goes on, no more being to be executed at one time than the painter can dispatch in a day, while it dries. Before he begins to paint, a cartoon or design is usually made on paper, to be chalked and transferred to the wall about half an hour after the plaster is applied.

The ancients painted on stucco; and we may remark in Vitruvius what infinite care they took in making the incrustation or plastering of their buildings, to render them beautiful and lasting; though the modern painters find a plaster of lime and sand preferable to it, both because it does not dry so hastily, and because, being a little brownish, it is fitter to lay colours on than a ground so white as stucco.

In this kind of painting, all the compound and artificial colours, and almost all the minerals, are set aside, and scarcely any thing is used but earths, which are capable of preserving their colour, defending it from the burning of the lime, and resisting its salt, which Vitruvius calls its bitterness.

For the work to come out in all its beauty, the colours must be laid on quick, while the plaster is still moist; nor should they ever be retouched dry with colours mixed up with the white of an egg, or size, or gum, as is sometimes done; because such colours grow blackish, and soon tarnish.

The colours used are white made of lime slaked some time previously, and white marble dust, ochre, both red and yellow, verditer, lapis lazuli, black chalk, and other similar substances. These only require to be ground and mixed up with water, and then laid on.

The brushes and pencils for this work ought to be long and soft, otherwise they will rake and raise the painting. The colours should be full and flowing from the brush, and the design perfect; for in this work you cannot alter or add upon any colour.