BOOK XXXV. XXV. 41-XXV1. 44 



factories have actually been built with no exit for 

 the smoke produced by this process. The most 

 esteemed black paint is obtained in the same way 

 from the wood of the pitch-pine. It is adulterated 

 by mixing it with the soot of furnaces and baths, 

 which is used as a material for writing. Some people 

 calcine dried wine-lees, and declare that if the lees 

 from a good wine are used this ink has the appearance 

 of Indian ink." The very celebrated painters 

 Polygnotus and Micon at Athens made black paint 

 from the skins of grapes, and called it grape-lees ink. 

 Apelles invented the method of making black from 

 burnt ivory ; the Greek name for this is elephantinon. 

 There is also an Indian black,^ imported from India, 

 the composition of which I have not yet discovered. 

 A black is also produced with dyes from the black 

 florescence which adheres to bronze pans. One is 

 also made by buming logs of pitch-pine and pounding 

 the charcoal in a mortar. The cuttle-fish has a 

 remarkable property in forming a black secretion, 

 but no colour is made from this.'' The preparation 

 of all black is completed by exposure to the sun, 

 black for writing ink receiving an admixture of gum 

 and black for painting walls an admixture of glue. 

 Black pigment that has been dissolved in vinegar 

 is difficult to wash out. 



XXVI. Among the remaining colours which be- Purpies. 

 cause of their high cost, as we said, are suppUed § so. 

 by patrons, dark purple holds the first place. It is 

 produced by dipping silversmiths' earth '^ along with 

 purple cloth and in like manner, the earth absorbing 

 the colour more quickly than the wool. The best 

 is that which being the first formed in the boiUng 

 cauklron becomes saturated ^ith the dyes in their 



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