LECTURE XIV.] HISTORY OF CHEMISTRY. 279 



although it appeared soon after that quinone did not belong 

 to the ortho-compounds, as Grabe supposed, but to the 

 para-compounds. 25 Grabe afterwards studied other quinones 

 also, and so arrived at the investigation of alizarine, the nature 

 of which as a quinone he desired to establish. In conjunction 

 with Liebermann, and by making use of a method discovered 

 by Baeyer, 26 he showed that alizarine was not, as was then 

 supposed, a naphthalene derivative, but that it was derived 

 from anthracene ; 2T that it was a quinone ; and that, in par- 

 ticular, it was a dioxy-anthraquinone. These chemists after- 

 wards accomplished the synthesis of this valuable colouring 

 matter, 28 which was at .once prepared technically according to 

 a method elaborated by Grabe, Liebermann, and Caro ; 29 thus 

 leading to one of the most extensive industries of the present 

 time. 



It may be stated generally that the theory of the aromatic 

 compounds had a great influence in technology and especially 

 in that of dyes. Although the aniline colour industry was 

 called into existence quite independently of these investigations 

 (especially by Hofmann's comprehensive researches on aniline, 

 and the bases homologous with it), and although the first 

 aniline colours had been discovered and turned to account long 

 prior to the publication of Kekule's celebrated paper mauveine 

 by Perkin 30 as early as 1 856, and fuchsine by Verguin 31 in 1859, 

 after it had been previously observed by Natanson, 32 Hof- 

 mann, 33 and others still its further development is intimately 

 connected with the more accurate insight into the constitution 

 of the aromatic compounds. With respect to this, it is only 

 necessary to recall the discovery of orthotoluidine by Rosen- 

 stiehl, 34 and the explanation of the chemical nature of rosaniline, 



23 Petersen, Berichte. 6, 368 and 400. 2G Annalen. 140, 295. 

 27 Berichte. I, 49. 28 Annalen. Supplementband 7, 257 ; Berichte. 

 2, 14. 29 Ibid. 3, 359. 30 Perkin, Zeitschrift fitr Chemie. 4, 700; 

 Annalen. 131, 201. 31 Repert. de Chimie appliquee. 2, 114, 299; 

 compare also Dingl. Polyt. Journ. 154, 235, 397. 3 ' 2 Annalen. 98, 

 297. s 3 Jahresbericht 1858, 351. :u Zeitschrift fur Chemie. u, 557; 

 12, 189-190. 



