COAL-TAR DYES 



261 



adopted it at once, but it was not until the French had shown 

 what beautiful patterns could be produced upon cotton 

 fabrics by its use that English cotton-printers realized its 

 value. After this its use spread very rapidly. There is an 

 amusing story told of how a traveller wandering in the 

 regions of North-West America came upon a party of native 

 Indians dyed to a man from head to foot in Perkin's mauve ! 



To Scrubbers 



t, Hm'fttr* 



DIAGRAM OF A GAS -MANUFACTURING PLANT 

 A, retort in which coal is heated. B, the hydraulic main. C, outlet 

 for the tar. D, gas pipe. E, tank in which the ammoniacal liquor collects. 

 F, cooling pipes. 



The next important discovery was made by Messrs. Graebe 

 and Liebermann in 1868 and 1869, and independently by 

 Perkin in 1869. Perkin found that Alizarin, the colouring 

 principle of Madder, could be produced from Anthracene, 

 another product of coal tar, and thenceforth this artificial 

 madder ousted the natural dye. 



In 1879 Professor Baeyer announced the chemical com- 

 position of Indigo, and in 1880 he found how it could be 

 produced artificially, but it was too dear for general use. 



