Wakeman—Pigments of Flowering Plants. 817 
and determined its empirical formula. Hlasiwetz 5 and Haber- 
v mann, in 1874, took up the study of the constitution of gentisin. 
In 1876 6 they found that it contains a methoxy group and ob¬ 
tained gentisein by hydrolysis. In 1891 Kostanecki 7 turned his 
attention to the constitution of gentisin and in 1894 8 succeeded 
in synthesizing gentisein from phlorogluein and hydroquinone 
carboxylic acid. From this product he readily obtained genti¬ 
sin by treatment with methyl iodide. The remaining question 
of the position of the methoxy group was answered by Perkin 9 
in 1898. 
Gentisein crystallizes in pale yellow crystals which melt at 
315°. It is soluble in alkalies with a bright yellow color. 
Gentisin forms fine needle like crystals of a pale yellow color. 
It forms well defined crystalline salts of sodium and potassium, 
C 14 H 9 NaO s and C 14 H 9 K0 5 . 
II. A. 1. d.) Hexhydroxy derivatives of diphenyl methanone. 
Datiscetin. 
Datiscetin has been known for a long time in southern France 
where it has been used as a coloring agent for silk. It was first 
studied by Braconnet 1 in 1816. Later Stenhouse 2 showed that 
the substance to which the coloring properties are due is a 
glucoside which may be hydrolized into datiscetin and rhamnose. 
In 1893 and 1894 Marchlewski 3 and Schunk undertook the de¬ 
termination of the constitution of datiscetin and found thot it 
belongs to the xanthone group of pigments, assigning to it the 
generally accepted formula C 15 H 12 0 6 with two hydroxy and two 
methoxy groups, as shown below. Upon treatment with hy- 
driodic acid datiscetin yields a tetra hydroxy xanthone of a 
yellow color. 
More recently, 1907, Marchlewski 4 claims that datiscetin is of 
the formula C 15 H 10 O 6 , that it melts at 268°-269° instead of 
6 Ann,, 25, p. 200. 
6 Ann., 62, p. 106. 
7 Monats., 12, p. 205; 12, p. 318. 
8 Monats., 15, p. 1; 16, p. 919. 
9 Jr. Chem. Soc., 73, p. 673. 
J Ann. Chim. et Phys., (2) 3, p. 277. 
a Ann., 98, p. 167. 
3 Ann., 277, p. 261; 278, p. 346. 
4 Biochem. Zeit., 3, p. 287; Chem. Centralbl., 1906, II, p. 1265. 
52 — S. A. L. 
