Besides this material, certain gums, and yolks of eggs, which easily deceive the eye of the less skilful, were also used, and very nearly resemble those pictures that display a scanty portion of oil, as is observed by Zanetti, in his account of Venetian painting (p. 20); and the analysis of Tommaso da Modena's picture has tended to confirm his opinion. This information I owe to the late Count Durazzo, who, in 1793, assured me, when at Venice, that he had himself beheld, at Vienna, the process of analyzing such pictures, by very skilful hands, at the command, and in the presence of Prince Kaunitz; and that it was the unanimous opinion of those professors, that no traces of oil were to be found. The colours consisted of the finest gums, mixed with the yolk and white of eggs, a fact that afforded just ground for a like conclusion in regard to similar works by the ancients. I fully appreciate, likewise, the opinion of Piacenza upon the celebrated picture of Colantonio; this I reserve, however, together with some further reflections of my own, for the school of Naples. I shall here merely inform the reader, that, in regard to the chemical experiments employed on these paintings, Sig. da Morrona[78] observes, that old pictures are often believed to be in a state of purity, when they have been retouched with oil colours at a subsequent period: the use of wax, and of essential oils, or of some such old methods, may frequently give rise to doubt, as I shall soon shew. Having removed the objections brought against the opinion of Vasari, I must add a few words in regard to a passage where he seems to have forgotten what he had said in the life of Angiol Gaddi, but which will in fact throw further light upon the question. He is giving an account of the paintings and writings of Andrea Cennini, a scholar of Angelo. This person, in 1437, that is, long before the arrival of Domenico, composed a work on painting, which is preserved in MS. in the library of S. Lorenzo. He there treated, says Vasari, of grinding colours with oil, for making red, blue, and green grounds; and various new methods and sizes for gilding, but not figures. Baldinucci examined the same manuscript, and found these words in the 89th chapter:--"I wish to teach thee how to paint in oil on walls, or on panel, as practised by many Germans;" and on consulting the manuscript, I find, after that passage, "and by the same method on iron and on marble; but I shall first treat of painting on walls." In the succeeding chapters he says, that this must be accomplished "by boiling linseed oil." This appears not to accord with the assertion of Vasari, that John of Bruges, after many experiments, "discovered that linseed oil and nut oil were the most drying. When boiled with his other ingredients they formed the varnish so long sought after by him and all other painters." On weighing the evidence, we should, in my opinion, take three circumstances into