BOOK XXXIII. Lvii. 162-164 



From blue is made the substance called blue wash, 

 which is produced by washing and grinding it. 

 Hhie wash is of a paler colour than blue, and it costs 

 10 denarii per pound, while blue costs 8 denarii. 

 Blue is used on a surface of clay, as it will not stand 

 lime. A recent addition has been Vestorian blue, 

 called after the man Vestorius who invented it ; 

 it is made from the finest part of Egyptian blue, and 

 costs 11 denarii per pound. Pozzuoli blue is 

 employed in the same way, and also near windows ** ; 

 it is called cyanos. Not long ago Indian blue or indigo. 

 indigo began to be imported, its price being 7 

 denarii ; painters use it for dividing-lines, that is, 

 for separating shadows from light. There is also a 

 blue wash of a very inferior kind, called ground blue, 

 valued at 5 asses. 



The test of genuine Indian bhie is that when laid 

 on burning coal it should blaze ; it is adulterated by 

 boiling dried violets in water and straining the 

 Hquor through linen on to Eretrian earth.^ Its use 

 as a medicament is to clean out ulcers ; consequently 

 it is employed as an ingredient in plasters, and also 

 in cauteries, but it is extremely difficult to pound up. 

 Yellow ochre used as a drug has a gently mordant 

 and astringent effect, and fills up ulcers. To make 

 it beneficial it is burnt in earthenware vessels. 



We are not unaware that the prices of articles 

 which we have stated at various points difFer in 

 different places and alter nearly every year, ac- 

 cording to the shipping costs or the terms on which 

 a particular merchant has bought them, or as some 

 dealer dominating the market may whip up the 



" I.e. it does not lose its colour in the light. 

 * See p. 283, note k. 



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VOL. IX. E 



