140 
whole of the alizarine, the excess of anthraflavic acid 
remaining in solution. From the lead precipitate alizarine 
may be obtained having all the properties of that substance. 
It is certain, therefore, that by the action of caustic potash, 
anthraflavic acid is converted into alizarine, the process 
being doubtless one of oxidation, though it should be stated 
that the conversion is never complete, probably because the 
action, if carried far enough to convert the whole of the 
acid, leads to the decomposition of the alizarine already 
formed. I am at present occupied with some experiments 
for the purpose of substituting an atom of hydrogen in 
alizarine by methyl, and thus forming anthraflavic acid 
synthetically. It is evident that the acid cannot be con- 
sidered as a methylic ether of alizarine, since both sub- 
stances combine with two atoms of base to form neutral 
compounds. If the substitution by methyl be possible, it 
must therefore take place in the radical of alizarine. The 
possibility of such substitutions is allowed by Griibe and 
Liebermann, who consider chrysammic acid for instance as 
anthracjuinone in which 4H are replaced by 4N0 2 . Should 
the synthesis just mentioned succeed, it will, I imagine* 
throw some light on the constitution of the so-called yellow 
colouring matters of madder, such as rubiacine and rubia- 
dine, which certainly contain 16 atoms of carbon, and may 
possibly turn out to be substitution products of alizarine. 
In what manner anthraflavic, with its 15 atoms of carbon, 
is formed from anthracene, which contains only 14, is not 
very clear. I imagined it to be just possible that the anthra- 
cene employed for preparing the alizarine supplied to me 
might have contained a higher hydrocarbon, say C 15 Hi 2 or 
methylanthracene, which, by oxidation, would yield methyl- 
anthraquinone, and at the end of the process methylalizarine. 
On requesting Mr. Perkin to favour me with his opinion on 
this point, he informed me, however, that my supposition 
was improbable, because the alizarine which he sent me was 
