Note 302 — BOOK II. (continued 2)

The idea that the brilliant colouring of the Venetian school was owing to the use of a peculiar vehicle for the colours, or a certain varnish, has been long entertained by artists and connoisseurs; and the opinion has been sanctioned by great names: yet it is highly probable that the great secret of the Venetian painters consisted not in vehicles nor in varnishes, but in employing mineral colours, and in laying them on the canvas as little mixed as possible. No colour derived from the vegetable kingdom will stand well when mixed with oil, and our best colours are composed of metallic oxides, or earthy bodies highly charged with those oxides. When colours are much mixed on the palette they become invariably muddy, and to him who aims at brilliancy of colouring no maxim is of greater consequence than to keep his palette as clean as possible. The use of transparent colours in the shadows is another great cause of brilliancy, and this cannot be obtained by the use of mixed colours. It is produced by what is called glazing, or laying transparent colours one over another. In nothing is the effect of glazing, in giving transparency, more obvious, than in the astonishing clearness of the skies and water in the works of the best Dutch artists. That the magical effect of Kuyp's pictures is thus produced, I had an opportunity of knowing, from the blunder of a picture-cleaner, who thought he had made a great discovery when he found the Rhine of a deep blue in a picture by this master; from which, along with the varnish, he had removed a thin coating of yellow, with which the blue was glazed over, to produce the beautiful greenish hue of the water. (Note by Dr. Traile.)