BOOK XXXV. XXVI. 44-xxvn. 46 



primary state, and the next best produced vvhen 

 white earth is added to the same liquor after the 

 first has been removed ; and every time this is 

 done the quaHty deteriorates, the liquid becoming 

 more diluted at each stage. The reason why the 

 dark purple of Pozzuoh is more highly praised than 

 that of Tyre or Gaetulia or Laconia, places which 

 produce the most costly purples, is that it combines 

 most easily with hysginum " and madder which can- 

 not help absorbing it. The cheapest comes from 

 Canosa. The price is from one to thirty denarii per 

 Ib. Painters using it put a coat of sandyx underneath 

 and then add a coat of dark purple mixed with egg, 

 and so produce the brilliance of cinnabar ; if they 

 wish instead to produce the glow of purple, they 

 lay a coat of blue underneath, and then cover this 

 with dark purple mixed v\ith egg. 



XXVII. Of next greatest importance after this is indigo. 

 indigo,^ a product of India, being a slime that adheres 

 to the scum upon reeds. When it is sifted out it is 

 black, but in dilution it yields a marvellous mixture 

 of purple and blue. There is another kind of it that 

 floats on the surface of the pans ^ in the purple dye- 

 shops, and this is the ' scum of purple.' People who 

 adulterate it stain pigeons' droppings with genuine 

 indigo, or else colour earth of SeHnus or ring-earth '^ 

 with woad. It can be tested by means of a Hve coal, 

 as if genuine it gives off a briUiant purple flame and 

 a smell of the sea while it smokes ; on this account 

 some people think that it is collected from rocks 

 on the coast. The price of indigo is 20 denarii per 



" Perhaps the vessels containing Tyrian purple. 

 ^* See § 48. Some white earth; but it is not known 

 whether it came from SeHnus in CiHcia or Selinus in Sieily. 



295 



