144 
discoverer, Liebermann. By tbe action on it of strong nitric 
acid it yields chrysammic acid, the nitro-acid first obtained 
from aloes by one of the authors many years ago. 
To these we have now to add— 
8. Isoanthraflavine, a substance accompanying artificial 
alizarine, generally found along with anthraflavine in the 
commercial product, and which we shall describe presently. 
Chrysophanic Acid , the crystalline colouring matter of 
rhubarb, which at one time occupied a place in the list has 
been erased, since it has been shown by Liebermann that it 
is in reality a homologue of alizarine, having the formula 
C 15 H 10 O 4 , and is derived not from anthracene, but from a 
methylanthracene. 
We propose in this paper to give an account of some 
experiments on two of these isomerides, viz., anthraflavic 
acid and the one generally accompanying it, which we have 
lately observed for the first time. 
Anthraflavic Acid or Anthraflavine. 
We have little to add to the description of this substance 
given in the paper above referred to. Its melting point is 
above 330°C. It is less soluble in glacial acetic acid than 
in alcohol. The analysis of a carefully purified specimen 
of the substance gave numbers agreeing exactly with the 
formula C 14 H 8 0 4 , and confirming the results obtained by 
Perkin. The barium salt, which has been previously 
described, loses when dried over sulphuric acid a con- 
siderable quantity of water, becoming at the same time 
much lighter in colour. On being now heated at a 
temperature of 150°— 180°C. it loses two molecules of water, 
and the dried salt has a composition corresponding with the 
formula C 14 H 6 Ba0 4 . Our results do not quite agree with 
those of Perkin, who found the formula of the salt dried at 
180° to be 2C 14 H 6 Ba0 4 , H 2 0. 
Tetrabromanthraflavine , C 14 H 4 Br 4 0 4 , is prepared by 
adding bromine in excess to an alcoholic solution of the 
