DR. E. SCHUNCK ON ANTHRAPLAVIC ACID. 2.29 



Messrs. Perkin and in a sample from a continental firm. 

 I therefore requested Mr. Perkin to supply me with a 

 quantity of commercial alizarine sufficient to enable me 

 to prepare a pure specimen of this body — a request to 

 which he very kindly acceded. 



The product supplied to me, which was a yellow, almost 

 amorphous powder, was in the first place treated with 

 dilute caustic soda, in which it dissolved for the most part, 

 yielding a dark purple solution. A small quantity of pale 

 yellow powder, consisting of impure anthraquinone, was 

 left undissolved. An excess of acid, adcied to the filtered 

 liquor, produced a bulky brownish-yellow precipitate, 

 which was filtered off and dissolved in boiling alcohol. 

 The alcohol, on cooling, deposited a quantity of almost 

 pure alizarine in small mica-like scales. The mother- 

 liquor was freed from alizarine by adding acetate of lead, 

 which gave a bulky purple precipitate. The filtered 

 liquid, which had a dark yellow colour, was evaporated, 

 when it left a yellowish-brown residue, consisting for the 

 most part of the yellow colouring-matter or acid. In 

 order to separate the latter from the impurities accom- 

 panying it, the residue was treated first with water and 

 then with cold alcohol, the latter of which removed a 

 quantity of a brown resinous substance. It was then 

 dissolved in dilute caustic soda; and the solution having 

 been raised to the boiling-point, chloride of barium was 

 added. The filtered liquor deposited, on cooling, a mass 

 of small shining crystals of the barium salt of the acid. 

 These were purified by recrystallization from boiling water 

 and then treated with hydrochloric acid. The lemon- 

 yellow flocks left by the acid were filtered off, washed, and 

 dissolved in boiling alcohol. This, on cooling, deposited 

 yellow silky needles, consisting of an acid which I have 

 named anthraflavic acid, in order to indicate its source 

 and its most obvious external property. 



