ISOMERIDES or ALIZARINE. 43 



tion-band on the confines of the green and blue. It is in- 

 soluble in dilute caustic potash lye. 



Analysis yielded the following results : — 

 0-2382 grm. of substance dried at I20°gave 0"6352 grm. 

 COi and o-ii66 grm. H^O. 



Dimethylanthraflavine was prepared by the same method 

 as diethylanthraflavine^ from which it can hardly be distin- 

 guished. It melts at 247°-248°. 



Isoanthraflavine. 



This isomeride of alizarine and anthraflavine was obtained 

 from a by-product of the manufacture of alizarine, which 

 Mr. Perkin kindly presented to one of us some time ago 

 for purposes of inve'stigation. According to Mr. Perkin, 

 this product had been obtained by treating crude alizarine 

 with lime-water, filtering the red extract and collecting the 

 precipitate produced on adding acid. 



The product was treated with dilute caustic soda lye, in 

 order to separate some anthraquinone which was present. 

 The filtrate gave with hydrochloric acid a yellow flocculent 

 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 anthra- 

 flavate, and was employed for the preparation of anthrafla- 

 vine. The blood-red solution gave on the addition of acid 

 a yellow precipitate consisting of isoanthraflavine. This 

 was purified by solution in boiling alcohol, from which it 

 crystallized in long needles of a yellow or brownish yellow 



