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 C14 H 8 0 3 , and consider it as monoxyanthraquinone, 
alizarine being dioxyanthraquinone. The results of their 
analyses of the substance and its barium compound differ 
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 with 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. 
