Cakes of colour have sometimes been found in the tombs, together with earthenware mortars and pestles for grinding them. The tints usually employed were _yellow_, _red_, _blue_, _green_, _brown_, _white_, and _black_. These correspond to the seven cups hollowed in most of the palettes. They each included several varieties. Some of these colours were vegetable, such as indigo; others--and these more numerous--were mineral. Among the latter is a certain blue, which has preserved all its brilliancy even after so many centuries. Its merits were extolled by Theophrastus and Vitruvius. It is an ash with wonderful power of resisting chemical agents, and neither turning green nor black with exposure to the air. It must have been composed, we are told, of sand, copper-filings, and subcarbonate of soda reduced to powder and burnt in an oven. Copper is also the colouring principle, at least in our days, of those greens which are more or less olive in tone. Different shades of red, yellow, and brown, were obtained from the ochres. Their whites, formed of lime, of plaster, or of powdered enamel, have sometimes preserved a snowy whiteness beside which our whitest papers seem grey.[330] As for violet, Champollion tells us that no colour used by the ancients had that value. In those few bas-reliefs in which it is now found, it is a result of the changes which time has spread over surfaces originally gilded. The hue in question is caused, we are told, by the mordant or other preparation upon which the gold was laid.[331] [330] Fuller details as to the composition of these colours are given in PRISSE, _Histoire de l'Art Égyptien_, text, pp. 292-295. A paper written by the father of Prosper Mérimée and printed by Passalacqua at the end of his _Catalogue_ (pp. 258, et seq.) may also be consulted with profit; its full title is _Dissertation sur l'Emploi des Couleurs, des Vernis, et des Émaux dans l'Ancienne Égypte_, by M. MÉRIMÉE, _Secrétaire Perpétuel de l'École Royale des Beaux-Arts_. This paper shows that M. Mérimée added taste and a love for erudition to the talent as a painter which he is said to have possessed. BELZONI shows that the manufacture of indigo must have been practised by the ancient Egyptians by much the same processes as those in use to-day (_Narrative of the Operations_, etc. p. 175). See also WILKINSON, _Manners and Customs_, etc. vol. ii. p. 287. [331] CHAMPOLLION, _Lettres d'Égypte et de Nubie_, p. 130. [Illustration: OFFERINGS TO THE DEAD FRAGMENT OF A FUNERARY PAINTING ON PLASTER (XVIIIth Dynasty)]