798 Wisconsin Academy of Sciences, Arts, md Letters. 
Pigments referable to o-xylene 
0‘Xylene OrseUinic acid 
Lecanoric acid, 27 ) another pigment forming substances from 
some varieties of Roccella, Lecanora, and Yariolaria, is prob¬ 
ably a condensation product of two molecules of orsellinie acid, 
referable to o-xylene, dimethyl 1, 2, benzene. 
Lecanoric acid crystallizes in colorless crystals. With alka¬ 
lies it gives a beautiful rose like color, with calcium chloride, 
a blood red color. It occurs combined with erythrite as the 
ester, lecanoryl erythrite, also known as erythrin. 
The constituents of other similar pigments found in these 
lichens is not known. 
Pigments referable to cymene 
Cymene llydrothymoquinone 
Hydrothymoquinone has already been discussed in connec¬ 
tion with thymoquinone in the preceding chapter. It occurs 
«Ann., 295, p. 278; 41, p. 157; 54, p. 261; 61, p. 72; Jr. Prakt. Chim. 
44, p. 18 ; Czapek, Biochemie der Pflanzen, p. 507, 
