68 HENRY G. SMITH. 



generally accepted that this position is necessary for the 

 hydroxyl radicles in the anthraquinone dyestuffs. 



The general structural formula for the members of the 

 quercetin or phenylated pheno-y-pyrone group is 



O 



CO 



the number and position of the hydroxyls in the molecule 

 characterising the several members of this group. The 

 following list includes most of the natural yellow dyestuffs 

 belonging to this group, the constitution of which are known, 

 and in which the hydroxyl radicles are intact : — 

 Myricetin, from the bark of Myrlca nagi, with 6 hydroxyls. 

 Quercetin, (from various sources), with 5 hydroxyls. 

 Morin, from Old Fustic, Morus tinctoria, with 5 hydroxyls. 

 Fisetin, from Rhus continus and R. rhodanthema, with 4 



hydroxyls. 

 Luteolin, from Weld, Reseda luteola, with 4 hydroxyls. 

 Kampherol, from galanga root, Alpinia officinarum, with 



4 hydroxyls. 

 Apigenin, from parsley, Apium petroselinum, with 3 



hydroxyls. 

 Galangin, from galanga root, with 3 hydroxyls. 

 Ohrysin, from poplar buds, with two hydroxyls. 



All these contain 15 carbon atoms in the molecule. 



Other members of this series are known which exist 

 naturally as methyl ethers. Rhamnetin, from Persian 

 berries, is the monomethyl ether of quercetin, and is a 

 typical example of the members belonging to this subclass. 



All natural colouring matters, however, do not belong 

 to the quercetin group, some being known that are deriva- 

 tives of the dipheno-y-pyrone or xanthone group 



