The colour of the canvas or panels on which pictures are intended to be painted should always be of a light colour, and the permanent brightness of a work will much depend on this. If a dark ground be employed, it will soon show through the light colours thinly painted on it.,Many of the pictures of the old Spanish School, being painted on a dull red ground, have become so dark, that the thinly painted parts are scarcely discernible. Nearly all the works by Nicolas and Gaspar Poussin are painted either on a red or umber ground, and the colour of the works of the former, which was never very pleasant, has at length become very offensive; this is due to the change referred to. Everthing considered, a pure white ground is preferable to all others, and pictures which have been painted with a fair impasto on a white ground, have been found to survive the ravages of time the best.,