230 DR. E. SCHUNCK ON ANTHRAFLAVIC ACID, 



The chief properties of this acid are these : — When 

 crystallized from alcohol and dried, it has the appearance 

 of a dark lemon-yellow silky mass, which, under the 

 microscope, is seen to consist of slender four-sided prisms. 

 Heated on platinum foil, it gives off copious yellow fumes, 

 and then burns with a luminous flame, without leaving any 

 residue. When cautiously heated between large watch- 

 glasses, it may be almost entirely volatilized, yielding a 

 vapour which condenses in the form of a yellow sublimate. 

 This sublimate consists of small lustrous crystalline plates, 

 some of which, when examined under the microscope, are 

 found to have very regular forms. The acid is only slightly 

 soluble in boiling water, and almost insoluble in cold. It 

 is more soluble in alcohol and ether, but insoluble in boil- 

 ing benzol and sulphide of carbon. It dissolves readily in 

 concentrated sulphuric acid even in the cold, forming a 

 yellow solution, from which it is precipitated, by water, in 

 yellow flocks. It is not much affected by dilute nitric acid 

 even on boiling. In fuming nitric acid it dissolves very 

 readily even in the cold, yielding a deep-yellow solution, 

 which, on standing for some hours, becomes lighter in 

 colour without evolving any gas. On now adding water, 

 a quantity of light-yellow shining crystals is deposited, 

 having the general properties of a so-called nitro-acid. 



The salts of anthraflavic acid are compounds of well- 

 defined character, some of them being regularly crystal- 

 lized. When an alcoholic solution of the acid is mixed 

 with an alcoholic solution of potash, it assumes a dark 

 yellow colour, and, on standing, deposits long orange- 

 coloured needles exhibiting considerable lustre. The 

 sodium compound, prepared in the same manner, crystal- 

 lizes in needles and resembles the potassium salt, but is 

 lighter in colour. The ammonium salt may be obtained 

 in dark -yellow lustrous crystals by dissolving the acid in 

 boiling absolute alcohol and adding a slight excess of 



