The nature of vehicles or liquid mediums to combine with the substance of colours, has been frequently discussed by modern writers on art, and may perhaps be said to have received as much attention as it deserves. Reynolds smiles at the notion of our not having materials equal to those of former times, and indeed, although the methods of individuals will always differ, there seems no reason to suppose that any great technical secret has been lost. In these inquiries, however, which relate merely to the mechanical causes of bright and durable colouring, the skill of the painter in the adequate employment of the higher resources of his art is, as if by common consent, left out of the account, and without departing from this mode of considering the question, we would merely repeat a conviction before expressed, viz. that the preservation of internal brightness, a quality compatible with various methods, has had more to do with the splendour and durability of finely coloured pictures than any vehicle. The observations that follow are therefore merely intended to show how far the older written authorities on this subject agree with the results of modern investigation, without at all assuming that the old methods, if known, need be implicitly followed. On a careful examination of the earlier pictures, it is said that a resinous substance appears to have been mingled with the colours together with the oil; that the fracture of the indurated pigment is shining, and that the surface resists the ordinary solvents.[1] This admixture of resinous solutions or varnishes with the solid is not alluded to, as far as we have seen, by any of the writers on Italian practice, but as the method corresponds with that now prevalent in England, the above hypothesis is not likely to be objected to for the present. Various local circumstances and relations might seem to warrant the supposition that the Venetian painters used resinous substances. An important branch of commerce between the mountains of Friuli and Venice still consists in the turpentine or fir-resin.[2] Similar substances produced from various trees, and known under the common name of balsams,[3] were imported from the East through Venice, for general use, before the American balsams[4] in some degree superseded them; and a Venetian painter, Marco Boschini, in his description of the Archipelago, does not omit to speak of the abundance of mastic produced in the island of Scio.[5]