THE COAL-TAR DYE INDUSTRY 127 



production was first accomplished in France by Berguin. 



The price of aniline, at first nearly three dollars per 

 pound, was soon lowered by competition. It was treated 

 with all sorts of reagents in the hope of producing new 

 dyes. A mixture of aniline and fuchsine yielded aniline 

 blue, and with the production of the first aniline yellow, 

 called chrysaniline or phosphine, a feeble competition with 

 vegetable dyes began. 



Practice outran theory and produced dyes of which the 

 chemical character and relations were little known. Again 

 it was Hofmann who illuminated the darkness. He deter- 

 mined the chemical nature of fuchsine and discovered iodine 

 violet and iodine green, which were at once manufactured 

 and put on the market. They were made under pressure, 

 often in old champagne bottles, which had a disagree- 

 able habit of exploding, but possessed the advantage of 

 cheapness. 



These two new dyes were discovered, or rather invented, 

 in accordance with scientific principles, and they proved 

 that the chemistry of the coal-tar colors was being developed 

 correctly. TLis development was further promoted by 

 Kekule's ingenious theory of the structure of the aromatic 

 hydrocarbons which solved the intricate problems of isom- 

 erism. 



Kekule's pupil, Bayer, was one of the first to apply this 

 theory to the coal-tar colors, and after seventeen years' 

 labor he achieved one of the greatest triumphs of chem- 

 istry, the synthesis of indigo. 



Meanwhile Graebe and Liebermann had taken up the 

 study of anthracene, also a constituent of coal tar. After 

 proving that anthracene can be obtained from alizarine, 

 the red coloring matter of the madder root, they endeavored 

 to reverse the process, and make alizarine from anthracene. 

 They succeeded, and so did Perkin, in the same year, 1869. 

 The German chemists applied for an English patent one 

 day earlier than their English rival, and so the English 

 market was secured for German artificial alizarine. Now 



