87 



presumed to be contained in it might be supposed to be 

 eliminated and replaced by hydrogen during the process. 



The examination of anthraflavic acid was subsequently 

 undertaken by Mr. Perkin,* whose analyses of the carefully 

 purified substance led to the conclusion that it is isomeric 

 with alizarine. I do not wish to dispute the accuracy of 

 this view of its composition, since a trifling admixture of 

 some impurity, such as anthraquinone, might easily have 

 given rise to the excess of carbon found in my analyses, though 

 I may state that a specimen of the substance, prepared from 

 some of the " by-product" of the manufacture of alizarine — 

 kindly sent me by Mr. Perkin — and purified with great 

 care, gave exactly the same composition as before. 



Graebe and Liebermann-[- have also examined a yellow 

 crystalline body accompanying artificial alizarine, which is 

 converted into the latter by the action of fusing caustic 

 potash. They are of opinion that it is identical with anthra- 

 flavic acid, there being, indeed, little or no difference in the 

 properties of the two substances. They assign to it the 

 formula Cu Hg O3, and consider it as monoxyanthraquinone, 

 alizarine being dioxyanthraquinone. The results of their 

 analyses of the substance and its barium compound diflfer 

 however so widely from those obtained by Mr. Perkin and 

 myself (particularly in this respect, that in the compounds 

 of anthraflavic acid, two atoms of hydrogen are replaced by 

 metals, whereas in those of monoxyanthraquinone only one 

 atom is replaced) as to lead to the conclusion either that 

 there exists more than one body having the general proper- 

 ties — chemical and physical — of anthraflavic acid, or that we 

 have not all of us been working mth pure substances. 



Without pronouncing any decided opinion on this point, 



which can only be determined by further investigation, and 



without entertaining any sanguine anticipation of being 



able to prepare anthraflavic acid directly from alizarine, it 



* Chem, Soc. J., XXIV, 1109, f Liebig's Annalen CLX., 141. 



