10 Trans. Acad. Sci. of St. Louis 



difficult to establish. After many efforts Graebe and 

 Liebermann in 1868 recognized that alizarine, which was 

 then known to be a constituent of Turkey red, the mad- 

 der dyestuff, was a derivative of anthracene and anthra- 

 cene was found in coal-tar. In the same year Graebe and 

 Liebermann succeeded in making artificial alizarine from 

 anthracene, which was identical with Turkey red. The 

 invention was quickly taken up by manufacturers and ar- 

 tificial alizarine superseded Turkey red, thus making 

 unprofitable the cultivation of the madder plant. In 

 1875 I had the privilege of meeting Liebermann and also 

 Hofmann on the occasion of the seventy-fifth anniversary 

 of Woehler's birth. On that occasion Prof. Liebermann 

 related to us how they had worked on the synthesis of 

 alizarine. When success was assured they repeated the 

 entire process in a single night, to make sure of results 

 before publication. At that time there was no patent 

 law in the North German Federation, and patents had to 

 be secured in three dozen principalities. This made 

 them of little value, and the inventors gave their work 

 to the public, securing for themselves only the immor- 

 tality of their names. 



The process of making artificial indigo is largely cred- 

 ited to Adolph V. Bayer, who recognized its constitution. 

 But many years of tedious work were required before 

 the Badische Aniline & Soda Fabrik succeeded in pre- 

 paring artificial indigo at a price capable of competing 

 with the natural article. Since 1897, however, artificial 

 indigo has been sold and soon afterwards a process was 

 worked out which made use of naphthalene as a raw 

 material. Naphthalene was always available in great 

 quantities and at a low price, and the naphthalene pro- 

 cess made it possible to drive natural indigo out of the 

 market. An interesting story is connected with the inven- 

 tion of the naphthalene process, the first step of which 

 was to transform naphthalene into phthalic acid. For- 

 merly phthalic acid was prepared by oxidation of Naph- 

 thalene with nitric acid or chromic acid at great cost. The 



