One curious and interesting discovery resulted from the demolition of this venerable tree. The woodman, who had allowed the smoke from his peat-piled fire to pass through one of the hollow limbs of the tree for several years without sweeping it, had, by accumulated incrustations, produced a mass of the finest brown colour, resembling the present appearance of that used by Rembrandt, so much coveted by the English artists. The discovery was made by Mr. Paul Sandby, who was fortunately passing at the time the timber was on the ground, who immediately secured a tolerable quantity to enable him to prove that the smoke from forest fuel, united with the heated branch of a hollow and aged beech, produced the finest bistre: his son, the present Mr. Sandby, gave me a lump of it, which I presented to the late Sir George Beaumont.[231] Having mentioned this bistre to several Roman artists, they informed me that a strong decoction of the sap of the ilex, or evergreen oak, produces a colour nearly similar; and of this I have had satisfactory proof. These, and suchlike bistres, would be much safer for the artist to use than that called sepia, which is made from the ink of the cuttle-fish, which, being a marine production, ever retains its saline and pernicious qualities, as may be seen in several of the numerous drawings made by Guercino, where the colour has left a blot, which has completely eaten through the paper. However, after all the trials of our experimentalists to match the present tint of Rembrandt’s drawings, and however pleasingly ingenious their discoveries have been, still I am inclined to believe that much, if not the whole, of the effect of old drawings is owing to that produced by time; and in this idea I am borne out by a small drawing which the ever-to-be-revered Flaxman made with a pen in common writing-ink: he drew it when I was a lad, and it is now a deep rich brown. May we not also fairly conclude, from the brown tint of most of our old manuscripts, that time has thus operated upon the ink? if so, the question is, what will the future colour of that which we now use in imitation, consisting of many ingredients, be, after fifty-five years, the elapsed time since I received my drawing from the kind hand of Flaxman? It is a curious fact, however, that the ink used by the ancient Egyptians on nearly two hundred specimens of the written inscriptions on papyrus collected by Mr. Salt,[232] now in the British Museum, are as jet a black as Cozens’s[233] blotting-ink, or Day and Martin’s far-famed blacking. 1788.