Miss Wheldale, On the natm^e of anthoci/anin. 145 



and flavone a ^-phenyl-benzo-7-pyrone : — 



Among those of other investigators, the very valuable researches 

 of Peekin^I""*" and his colleagues on the yellow colouring matters 

 of plants in connection with their dyeing properties, have thrown 

 much light on the constitution of these bodies, and since they are 

 of great importance in connection with this point I propose giving 

 a short account of the properties and constitution of the chief 

 members of the group, as well as their distribution among various 

 natural orders. The xanthones appear to be less widely distributed 

 than the flavones and it is to the latter that most importance 

 may be attached. 



Most of the colouring matters may be regarded as arising 

 from a hydroxy-derivative of flavone : — 



^C'CH. 



COH 



CO 



Generally speaking they are yellow crystalline bodies, not very 

 soluble in water in the free state, more soluble probably as 

 glucosides. They are soluble in acids giving yellow, orange or 

 red solutions, and in the absence of water many form crystalline 

 compounds Avith a molecule of the acid, these same compounds 

 being again decomposed into acid and colouring matter on addition 

 of water. At the same time they appear to have basic properties ; 

 in alkalis they are soluble, giving again yellow, orange or red 

 solutions. Many, moreover, are able, in the absence of water, 

 to withdraw potassium from potassium acetate, with the formation 

 of a mono-potassium salt. They are precipitated by lead acetate 

 as yellow, orange or red precipitates and with ferric chloride 

 solution they usually give a dull green colouration, occasionally 

 reddish-brown. The decomposition products on fusion with alkali 

 are frequently phloroglucin and protocatechuic acid, though some- 

 times resorcinol, resorcylic or hydroxybenzoic acids are formed 



