We have ourselves, in this Magazine, on a former occasion, spoken of a sort of distemper painting--though to give it that name is not very highly to recommend it. We have, nevertheless, found it very good, and admirably adapted for getting in a subject, as affording means of great rapidity of execution. We allude to the admixture of starch and oil--the less oil the more like distemper will it be; or, we should rather say, fresco, which it much more resembles; but oil may be used with it in any proportion. The starch should be made as for domestic use, with water saturated with borax, and the oil added by degrees, and the whole stirred up together while warm; and, in this medium, the colours should be ground as well as worked. It is curious that here, too, the borax is of use; for it not only enables the oil to mix with the water of the starch, but it gives the starch a consistence and toughness, which without it it never possesses. We have found colours retain their hue and purity remarkably well with this vehicle. The whole bears out equally, but without shining. The second painting may produce any desired richness. It is not unpleasant to paint upon a wet ground made with this vehicle, when the picture and ground will dry and harden together.
There is no colour concerning which we are more at a loss in looking at old pictures, than the blues. Three are mentioned by Cennino--indigo, a cobalt, and ultramarine. With regard to the sparing use of the latter, as the most expensive, some practical hints may be met with. We have often wondered with what blue their deep-toned cool greens were made, as in the landscapes of Gaspar Poussin. It was probably Cennino's _azzuro della magna_ (German blue or cobalt.) Prussian blue is of recent invention. We believe Mr Field considers it a good colour. It is made of so many hues that it is difficult to procure good, and it is said to be affected by iron. We have heard indigo complained of as a fugitive colour; Cennino mentions it for skies with a tempera of glue. He mentions, likewise, a green cobalt, or _azzuro della magna_. White lead, according to him, may be used with all temperas. He says it is the only white that can be used in pictures; the whites in the old pictures are very pure, so that we may be satisfied of its durability. Many artists have doubted if the white of the best painters was white lead, and many substitutes have been proposed. We may rest assured, by the authority of Cennino, that the fault is not in the lead, but in the vehicle, whenever it changes. There is a letter of Titian's, in which he laments the death of the maker of his white; it was made, therefore, we are to suppose, with particular care, as the principal pigment for light.