I cleaned and restored in the summers of the years 1827, 1828, and 1829, a great number of Italian and Flemish pictures, collected by Mr. John Webb, during his tour in Italy and Flanders, &c.; and, as many of them had been much injured, I had an opportunity of examining the grounds upon which they were painted. Those of the older Italian and Flemish artists were invariably painted upon a white, or nearly so, absorbent ground; and of the whole number, the oil ground did not seem to be the one much in use. In the collection at Kensington Palace, is a portrait of Dr. Linacre, the founder of the College of Physicians, painted by Holbein. The late Mr. Miller was engaged to make a copy of it, for the college, some years ago: it was painted, he found upon inspection, on a white absorbent ground; and by following the system of that school, in transparent glazings and retouchings, the result was a close and almost deceptive imitation of the portrait.,