COLOURS FOUND AT POMPEII. 



305 



Tliis ro-e colour may be considered as a true lake, in A lake 

 winch the colouring principle is mixed with alumine. Its 

 properties, its tint, and the nature of its colouring princi- 

 ple, give it an almost perfect similarity to the madder lake, probably from 

 which I have mentioned in my Treatise on Dyeing Cotton. madtler - 

 The preservation of this lake for nineteen centuries without 

 any perceptible alteration is a phenomenon* that must asto- 

 nish the chemist. 



Such is the nature of the seven colours, which have been Used as paints 

 put into my hands by her majesty the empress. They ap- 

 pear to have been absolutely designed, for painting : yet, if 

 we examine the glaze or coating of the Roman pottery, and perhaps 

 vast quantities of fragments of which are found in all or I ,otter >' 

 places, where their armies successively established them> 

 selves, we shall readily be of opinion, that most of these 

 earths may have been employed, to form the coating of this 

 earthenware. 



In fact, most of this pottery is covered with a red coat, Roman earth- 

 wliich is in no degree vitreous, and may have been given eaware » 

 by the yellow ochre, or the brown red, reduced by tritura- 

 tion to a fine paste, incorporated with some mucilaginous, 

 gummy, or oily substance, and laid on with a pencil. Mr. 

 d'Areet, who has examined the Roman pottery with great 

 skill, has a vase, the substance of which is of a dull red, 

 and the surface of which was coated with something of this coated, 

 kind. The place where the workman left off coating the 

 vessel may be seen; and on the bottom, which is not coated, 

 may be seen red strokes, made by the workman to try his 

 colour or his pencil. 



It is not uncommon to find other vessels, the substance of 

 which is of a diiferent colour from the red coating, that co- 

 vers the snrf;u'e. 



Pe haps tiie Romans even employed saline fluxes, to fa- and pe:rnps 

 cilitate the baking of the outer coat of their pottery. Fjjjj" fllix ^ 



Mr. d'Areet has perfectly imitated the white covering of white of the. 

 the Etruscan vases, by usmg a clay that bakes white, with Etruscaava.es, 

 which he mixed a twentieth part of borax. 



it appears, that in the first century of our era the Romans Metallic fluxes 

 were unacquainted with the use cf metallic fluxes, to fix Jil^KomLns. 

 and vitrify, the coating of pottery. At least the anuly is of 



Vol. XXIV— Dec. isoy, X the 



