886 Wisconsin Academy of Sciences, Arts, and Letters. 
Tschirch and Heuberger, — Arch. d. Pharm., 240, p. 605. 
Tschirch, — B., 8, p. 189. 
Tutin and Clewer, — Jr. Chem. Soc., 97, p. 1. 
Yogel, — Arch. d. Pharm., 134, p. 37 (1868). 
Trihydroxides of menthyVl-anthraquinones. 
Two trihydroxides of methyl-l-anthraquinone, emodin, and 
aloeemod'in, are known to exist in plants. These two isomeric 
pigments occur together in various species of aloes and senna, 
along with chrysophanic acid, of which emodin is a hydroxy 
substitution product. 
Emodin, 1 a methyl -l-trihydroxy-2, 1', 4'-anthraquinone, or 
methyl-l-trihydroxy-3, 1', 4'-anthraquinone is an hydroxy sub¬ 
stitution product of chrysophanic acid. 
Emodin occurs in various species of aloe, 2 including Aloe 
ferox, 3 Aloe vulgaris , 4 and Aloe chinensis ; 5 in Rheum officinale, 6 7 
Rheum palmatum, 1 Polygonum cuspidatum, 8 Cassia occiden¬ 
talism Cassia sophora, 9 Cassia tora, 10 Cassia angustifolia 9 
Xanthoxylon tingoassuiba, 11 Rhamnus cathartica, 12 Rhamnus 
japonica, 13 14 Rhamnus purshiana, 14: and Rhamnus frangula , 15 
1 Jr. Chem. Soc., 83, p. 1327. 
a Jr, Fharm. Chim., 28, p. 529. 
8 B. Pharm. Ges., 1898, p. 174. 
4 Arch. Pharm., 236, p. 200. 
5 Arch. Pharm., 241, p. 340. 
6 C. r., 136, p. 385. 
7 Ber., 1882, p. 902; Pharm. Jr. Trans., 15, p. 136. 
8 Bull. Sci. Pharm., 14, p. 698. 
9 Apoth. Ztg., 1896, p. 537. 
10 Pharm. Jr. Trans., 3, p. 242. 
11 B. Pharm. Ges., 9„ p. 162. 
13 Jr. Russ. Phys. Chem. Ges., 40, p. 1502. 
13 Apoth. Zt g., 1896, p. 537. 
14 Arch. Pharm., 246, p. 315; Jr. Pharm. Chem., 246, p. 315. 
16 Ber., 9, p. 1775; Pharm. Jr., 20, p. 558; Arch. Pharm.., 246, p. 315. 
