DR. E. SCHUNCK ON ANTHRAFLAVIC ACID. 235 



If the formula C IS H IO 4 for anthraflavic acid were cor- 

 rect, it would stand in a very simple relation to that of 

 alizarine, and the conversion of the acid into alizarine by 

 the action of caustic alkalies would not be difficult to 

 understand. If, however, the crude material which I 

 employed was prepared from pure anthraquinone, as I am 

 informed it was, it is not easy to see how a substance with 

 15 ats. C could have been obtained from it, and it may 

 therefore be questioned whether the acid examined was 

 perfectly pure. An experiment which I made for the 

 purpose of removing doubt on this point, rather tends to 

 increase it. Having heated a quantity of the acid with 

 fifty times its weight of zinc powder, in the manner de- 

 scribed by Graebe and Liebermann, I obtained a quantity 

 of a brownish crystalline sublimate, amounting to about 

 10 per cent, of the substance employed, and consisting 

 apparently of anthracene. It still retained, after being 

 purified as far as possible, the yellowish tinge which, 

 according to the chemists just named, adheres so perti- 

 naciously to anthracene ; but it did not differ in other re- 

 spects from the pure substance. It melted at the same 

 temperature as anthracene, and began to sublime before 

 fusing ; it dissolved in boiling alcohol, but more readily in 

 benzol, and was deposited from these solutions in lustrous 

 crystals of a very regular form ; and it gave, like anthra- 

 cene, with picric acid a compound crystallizing in long red 

 needles. If,- by heating with metallic zinc, anthraflavic 

 acid, like alizarine, yields anthracene, we may infer, in 

 accordance with the principle laid down by Graebe and 

 Liebermann, that it also contains 14 ats. C. It is evident, 

 therefore, that further experiments are required in order to 

 ascertain exactly the composition and formula of the acid. 



