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rial has prevented my examining this product more fully. 
Though anthraflavic acid yields intensely yellow com- 
pounds with bases, it seems to possess no dyeing properties. 
The freshly precipitated acid suspended in water communi- 
cates not the least tinge of colour to alumina and iron 
mordants on calico, however long the liquid may be boiled. 
Its presence in artificial alizarine is therefore of no conse- 
quence as regards the dyeing qualities of the latter. 
The composition of anthraflavic acid is expressed by the 
formula C 15 H 10 O 4 . That this is the true formula was proved by 
an examination of the silver and barium salts. The formula 
of the first is C 15 H 8 Ag 2 0 4 ; that of the second C 16 H s Ba0 4 + H 2 0. 
The additional molecule of water attached to the barium 
salt is not driven off by heating to a temperature of 120°C. 
The acid is therefore bibasic. Hence it appears that this 
substance and alizarine stand in a very simple relation to 
one another. They are homologous bodies. Anthraflavic 
acid may be viewed as alizarine in which an atom of hydro- 
gen is replaced by methyl. Though the great difference in 
properties, and especially the far greater stability of the acid, 
might lead to the inference that it is only as regards their 
composition that the two substances approach one another, 
a very simple experiment is sufficient to prove that they 
are in fact very closely related. If pure anthraflavic acid 
be dissolved in an excess of caustic potash, and the solution 
be boiled down to dryness, a yellow residue is left, which, 
after being carefully heated almost to fusion, dissolves in 
water with a red colour. This solution contains alizarine, 
as it shows the absorption bands in the spectrum peculiar 
to the latter, though not very clearly on account of unde- 
composed anthraflavic acid still present. Pure alizarine 
may, however, be obtained from it, by simply adding an 
excess of acid, filtering off the flocculent precipitate, dissolv- 
ing the latter in alcohol, and adding to the solution acetate 
of lead, when a purple precipitate falls, which contains the 
