146 
Isoanthraflavine. 
This isomeride of alizarine was prepared from a by-pro- 
duct of the manufacture of alizarine supplied to us some 
time ago by Mr. Perkin, and which, according to the latter, 
had been obtained by treating the crude alizarine with lime- 
water, filtering and precipitating the red extract with acid. 
The product was treated with dilute caustic soda lye, in 
order to separate some anthraquinone. The filtrate gave with 
hydrochloric acid a yellow gelatinous precipitate, which was 
filtered off and treated with cold baryta water, until nothing 
more dissolved. The residue left undissolved after this 
treatment consisted of barium anthraflavate, and was em- 
ployed for the preparation of anthraflavine. The blood-red 
solution was mixed with hydrochloric acid, which gave a 
yellow precipitate consisting of isoanthraflavine. This was 
purified by repeated crystallisation from boiling alcohol, 
and was obtained in long yellow crystalline needles. Some- 
times it yielded golden yellow lustrous scales, but these on 
recrystallisation always gave needles. These needles, after 
drying over sulphuric acid, still contain one molecule of 
water of crystallisation, which is driven off by heating to 
120°. The dried substance has a composition agreeing with 
the formula C 14 H 8 0 4 , five analyses giving as a mean C69 , 79> 
H365, the calculated amounts being C7000, H3*33. The 
properties of isoanthraflavine resemble those of anthra- 
flavine. It melts at a temperature above 330°. When 
slowly heated between watch-glasses it yields a sub- 
limate consisting of lustrous bright yellow needles and 
plates. It is a little more solub]e in boiling water than an- 
thraflavine. It dissolves easily in boiling alcohol and in hot 
concentrated sulphuric acid, but is almost insoluble in benzol 
and chloroform. It imparts no colour whatever to mordants 
and differs in this respect very widely from alizarine. It 
may be easily distinguished from anthraflavine by the colour 
of its alkaline solutions, which is distinctly red, while the 
