§ 152. QUEECITRIN, QUEECETIN, ETC. 139 



easily dissolved. They are both very slightly soluble in cold 

 water ; quercetin even in hot. They dissolve in the fixed and 

 volatile alkalies, and in alcohol, crystallizing from the latter 

 in yellow needles. Ferric chloride colours the alcoholic solu- 

 tions green (quercetin red, on warming) ; acetate of lead pro- 

 duces orange-red and 'brick-red precipitates respectively. Both 

 quercitrin and quercetin reduce solutions of gold and silver salts, 

 and also alkaline-copper solution after prolonged boiling. Heat- 

 ing with mineral acids resolves quercitrin into isodulcite and 

 quercetin (Löwe contradicts this, and asserts that Avater alone is 

 given off). It may be extracted from aqueous solution by agitation 

 with amy lie alcohol. ^ It melts at 130° to 133°, and is insoluble 

 in benzene, petroleum spirit, chloroform, and bisulphide of 

 carbon. 



In close relation to, but not identical with, quercitrin or rutin 

 stands the violaquercitrin recently isolated by Mandelin^ from 

 Viola tricolor. It Avas deposited in yellow acicular crystals on 

 saturating the aqueous solution Avith benzene. Boiling Avith 

 dilute acids decomposed it with production of glucose, quercetin, 

 and a third body as yet not further investigated. 



A body allied to quercetin appears to occur in the rhizome of 

 Podophyllum peltatum.^ According to Podwissotzky, the other 

 important constituents of this drug are fodophyllotoxin, Avhich 

 melts at 115° to 120°, is sparingly soluble in A\'ater, soluble in 

 ether and chloroform, and precipitated from chloroformic solution 

 by petroleum spirit ; picropodophylUn, Avhich is easily crystallizable, 

 and soluble in 95 per cent, spirit, ether and chloroform, but 

 insoluble in milk of lime and ammonia ; and jJodojAyllic acid. 



Gentisin is said to require 2,000 parts of cold ether for solution, 

 and must therefore be looked for in the alcoholic extract. It forms 

 pale yellow silky needles, Avhich can be partially sublimed Avithout 

 decomposition, requires 5,000 parts of cold, 3,850 of hot AA^ater, 

 455 of cold and 62-5 of hot absolute alcohol for solution. Ferric 



' Compare Johanson, ' Zur Kenntniss einzelner chemischer Bestandtheile 

 der Weiden,' etc. Archiv d. Pharm. [3], xiii. 110, 1878 (Pharm. Journ. and 

 Trans. [3], viii. 69). For Lowe's paper see Zeitschr. f. anal. Chemie, xiv. 

 233, 1875 (Journ. Chem. Soc. xxix. 108). See also Liebermann and Ham- 

 burger, Ber. d. d. chem. Ges. xii. 1178, 1879 (Journ. Chem. Soc. xxxvi, 944). 



^ Sitz-Ber. d. Dorpater Naturforscher, Ges. 1882, p. 343. 



^ Compare Podwissotzky, Archiv f. Pharm, und exper. Pathologie, 29, 1880 

 (Pharm. Journ. and Trans. [3], xii. 217, 1011). 



