Wakeman—Pigments of Flowering Plants. 801 
mono potassium salt” C 18 H 11 0 8 K and the mono potassium salt 
C 9 H 5 0 4 K. The former crystallizes in bright yellow and the 
latter in red crystals. To wools mordanted with chromium, 
aluminum, tin and iron it imparts various shades of olive and 
yellow. 
Daphnetin occurs as the glucoside daphnin, in the bark and 
flowers of Daphne mezerum 8 ) and in the leaves, bark and flow¬ 
ers of Daphne Alpina. 4 ) In these plants, however, the odori¬ 
ferous principle is not cumarin but umbelliferone, a 4-hydroxy 
cumarin. 
Daphnin, or a glucoside similar to daphnin has, furthermore, 
been reported in Panicum italicum 5 ) (Italian millet.) 
Closely related to daphnetin are aesculetin, scopoletin, and 
fraxetin, substances which though not colored themselves form 
beautifully fluorescent solutions. Moreover, at least some of 
their metallic derivatives, in which form they would be likely 
to occur in plants, are colored. 
Aesculetin is isomeric with daphnetin, being a 4, 5-dihydroxy 
cumarin. It forms a bright yellow potassium compound very 
similar to the corresponding daphnetin derivative. Its solu¬ 
tions show a beautiful blue fluorescence. Aesculetin occurs as 
the glucoside aesculin in Aesculus hippocastanum , 6 ) the horse 
chestnut, and in Gelsemium semper virens. 7 ) In the free state, 
is found in Euphorbia lathyris. 8 ) 
Scopoletin, a methyl ether of aesculetin occurs as the gluco¬ 
side scopolin in Gelsemium sempervirens 10 ) and in several 
species of Solonaceae, Atropa belladonna, * 11 ) Scopola japon- 
ica, 12 ) Mandragora autumnalis, 18 ) and Fabiana imbricata. 11 ) 
Scopoletin gives a blue fluorescence in solutions. Many of its 
metallic derivatives are colored. 
Fraxetin , another beautiful fluorescent substance is a deriva¬ 
tive of tetra hydroxy cinnamic acid. It may be considered as a 
3 Ann., 84, 173. 
4 Zwenger’s Ann., 115, 1. 
5 Ann. Chem. Jr., 20, 86. 
6 Arch. Pharm., 38, 330. 
T Ber., 9, 1182. 
8 Ber., 23, 3347. 
9 Czapek—Biochemie der Pflanzen, p. 563. 
10 Am. Jr. Ph., 42, p. 1; 54, p. 337; Arch. Pharm., 236, p. 329. 
11 Arch. Pharm. 228, p. 438, 440. 
13 Same as 11. 
13 Jr. Prakt. Chem., 172, p. 274. 
14 Arch. Pharm., 237, p. 1. 
51—S. A. L. 
