148. RHINACANTRIN, ALKANNIN, ETC. 135 



into sugar and alizarin. According to Stenhouse, morindin is 

 identical with ruberythric acid, morindon with alizarin (which is 

 doubted by Stein), and munjestin with purpurin. 



With regard to the constituents of madder that have been here 

 mentioned, and some others that accompany or can be obtained 

 from them, I refer in particular to the investigations of Schunk, 

 Eochleder, Stenhouse and others, for an account of which 

 Gmelin's * Chemistry ' may be consulted. 



For rhamnin, xanthorhamnin, chrysorhamnin, and their allies, see 

 Fleury and Biswanger, 1 Ortlieb, Liebermann, and Hermann. 2 



Bhinacanthin, discovered by Liborius in Rhinacanthus com- 

 munis, appears to possess some of the properties common to 

 anthraquinone-derivatives. 3 It occurs in the intercellular spaces 

 in the root bark, is soluble in ether, alcohol and dilute alkali, but 

 insoluble in pure and acidulated water. Alkalies produce a deep red 

 colouration, which is discharged or changed to greenish by acids. 



Alkannin is insoluble in water, but yields fine red solutions 

 with ether, alcohol, bisulphide of carbon, fixed and ethereal oils. 

 The spectrum is figured on Plate I, 11. Alkannin is uncrys- 

 tallizable, dissolves in concentrated sulphuric acid (violet), in 

 alkalies (blue), and in alcoholic ammonia. 



Bixin behaves similarly to water, alcohol and ether. It dissolves 

 in aqueous alkalies also (but the compounds thus produced are 

 sparingly soluble in alcohol), and is coloured blue by concentrated 

 sulphuric acid. 4 



Curcumin 5 is also insoluble in water, but is dissolved yellow by 

 ether and alcohol, brown by alkalies. Boracic acid colours it red, 

 changing to dark blue on the addition of an alkali. (For its spec- 

 trum see Plate I., 12.) 



For cambogic acid, which is dissolved yellow by concentrated 

 sulphuric acid, see Johnstone 6 and Buchner. 7 



1 Journ. de Pharm. et de Chim. xxvii. 666 ; Repert. f. Pharm. civ. 54. 



2 Bull, de la Soc. de Mulhouse, xxx. 16 ; Ber. d. d. chem. Ges. xi. 1618. 

 See also Lefort und Stein, Jahresb. f. Pharm. 145, 1867 ; 127, 1868 ; 123, 

 1869 (Journ. Chem. Soc. xxxvi.). 



3 Sitz-Ber. d. Dorpater Naturf. Ges. 277, 1879 (Pharm. Journ. and Trans. 

 [3], ix. 162). 



4 Compare Stein, Chem. Centralblatt, 939, 1867. 



8 See Linda und Daube, Journ. f. prakt. Chem. ciii. 474, and New Series, 

 ii. 86, 1870 (Journ. Chem. Soc. xxiv. 152). 



6 Phil. Mag. 281, 1839. 



7 Annal. d. Chem. und Pharm. xlv. 72, 1843 (Amer. Journ. Pharm. xv. 129). 



