802 Wisconsin Academy of Sciences, Arts, md Letters. 
methyl ether of hydroxy daphnetin or aesculetin, or as a methyl 
ether of trihydroxy cumarin. 
Fraxetin occurs along with aesculetin as the glucoside fraxin 
in the horse chestnut. 15 ) It occurs as the glucoside fraxin in 
Fraxinus excelsior™) Fraxinus ornus, 17 ) also both in the free 
state and as glucoside in Fraxinus americana. 18 ) 
Fraxetin gives a blue fluorescence in solutions. Many of its 
metallic derivatives are colored. The position of the methoxy 
group in fraxetin is not known. 
Pigments referable to hydrocarbons of the formula of 
SATURATION Cn H 2n _ 10 . 
Under this formula of saturation one pigment of known con¬ 
stitution, juglone, referable to dihydro naphthalene, and two 
others probably derivatives of methyl dihydro naphthalene have 
been isolated. All three of these compounds are hydroxy 
naphthaquinones, possessing both phenol and quinone proper¬ 
ties and capable of forming phenoquinones and quinhydrones 
with themselves and with the corresponding hydroquinones. In 
addition to these naphthaquinone pigments one, referable to di¬ 
dihydro phenyl ethane has been isolated. 
Pigments referable to dihydro naphthalene. 
Jaglone 
Juglone, a hydroxy derivative of naphtha quinone, is found 
in all the green parts of the walnut tree, Juglans regia, 1 ) and 
especially in the green shells of the nuts. Associated with it 
16 Fogg. Ann., 107, p. 331. 
ie Pog;g. Ann., 98, p. 637. 
1T Pogg. Ann., 98, p. 637: C. r. 51, p. 31. 
18 Am. Jr. Ph., 54, 282; 54, 99. 
*C. N., 141, p. 838 ; Ber. Repert., 5, p. 106 ; 7, p. 1; Her., 10, p. 1542. 
