SCIENCE IN THE INDUSTRIAL WORLD 



stopped the raising of madder is stopping the impor- 

 tation of indigo into Europe and every other civilized 

 land, more effectually than legislation could ever do. 

 Germany has perfected methods of manufacturing 

 from coal-tar an indigo that swiftly and surely is re- 

 placing the natural product. 



In point of age indigo is one of the oldest known 

 colors. The Egyptians used it sometimes to color the 

 wrappings of their mummies, and the fact that these 

 wrappings still show the blue color attests the perma- 

 nency of the pigment. The younger Pliny in his Nat- 

 ural History gives a very exact description of indigo, 

 and some tests for detecting it. Among other things he 

 mentions that when heated over a fire it "burns with a 

 purple flame and gives off a smell of tea." 



Until the opening years of the present century, 

 artificial indigo was not able to compete with the natural 

 product, about five thousand tons of which were used 

 annually. But German manufacturers were perfecting 

 methods, and in 1908 about one-fourth of the indigo 

 used was of artificial manufacture. This leaves little 

 room for doubt that it will be only a matter of a few 

 years before the indigo-growers of the world will be 

 obliged to devote their fields and energies to growing 

 some other crop, probably less profitable. 



Logwood, the wood of Hcematoxylon campechianum, 

 from which red, blue, violet, and black colors can be 

 obtained, is another important New- World contribu- 

 tion which the Spaniards discovered in South America. 

 For four centuries it was one of the most important of 

 dyestuffs, but, like indigo, it is now being rapidly dis- 



